Gwangju, South Korea
Gwangju, South Korea

Chonnam National University is a South Korean university located in the metropolitan city of Gwangju which lies in the middle of South Jeolla or Jeonnam province, for which the school is named in the Southwest of the country. The university was formally established in January, 1952 through the union of Gwangju Medical College, Gwangju Agricultural College, Mokpo Commerce College, and Daeseong College. It currently consists of 59 academic departments in 19 colleges and 11 graduate programs. University attached facilities are the University Library, Museum, Health Service Center, Agro-Bioindustry Technical Support Center, Animal Hospital, Language Education Center, School of Lifelong Education, and University Computing Center. In March 2006, Yeosu National University merged with Chonnam National University to become a satellite campus.Chonnam National University used to be generally regarded as one of the five major national universities of South Korea together with Seoul National University, Pusan National University, Kyungpook National University, and Chungnam National University. Now the number of the key national universities has been expanded into ten. CNU is also recognized as one of the best performers in government supported HRD projects. Research expenses of CNU ranks 13th nationally. Moreover, the number of High-ranking public officials ranked 11th. In addition, 26 alumni passed the Second Round of the 51st national bar exam, which is the biggest since the CNU Law School was established. Wikipedia.

Time filter

Source Type

Chonnam National University | Date: 2015-03-16

The present invention relates to a foldable case-integrated multi-device and a health management system using the same, in which health management and life management functions are implemented by introducing various sensors into a foldable case for a communication device. According to the present invention, a sensor module configured to measure biometric information is contained in a foldable case, and power supply, data processing and analysis, and display are implemented using internal components of the communication device, thereby providing a cutting-edge health care function while maintaining a communication device in a light, thin, short and small form.

Disclosed is a non-reducing end unsaturated mannuronic acid oligosaccharide having a molecular weight of 100-3000 Da, which is obtained by lysing polymannuronate as a substrate with alginate lyase, and provided are: a non-reducing end unsaturated mannuronic acid oligosaccharide; and pharmaceutical compositions for alleviating, preventing, or treating obesity, diabetes, and climacteric syndrome, and probiotics for promoting intestinal beneficial bacteria, the compositions and probiotics containing, as an active ingredient, the non-reducing end unsaturated mannuronic acid oligosaccharide, so that the antiobesity and antidiabetic effects, estrogen activity, and intestinal microflora controlling effect of the non-reducing end unsaturated mannuronic acid oligosaccharides are remarkably excellent as compared with non-reducing end saturated mannuronic acid oligosaccharides.

A method for preparing a catalyst having catalytically active materials selectively impregnated or supported only in the surface region of the catalyst particle using the mutual repulsive force of a hydrophobic solution and a hydrophilic solution and the solubility difference to a metal salt precursor between the hydrophobic and hydrophilic solutions. The hydrophobic solvent is a C2-C6 alcohol. The hydrophobic solvent is introduced into the catalyst support and then removed of a part of the pores connected to the outer part of the catalyst particle by drying under appropriate conditions. Then, a hydrophilic solution containing a metal salt is introduced to occupy the void spaces removed of the hydrophobic solvent, and the catalyst particle is dried at a low rate to selectively support or impregnate the catalytically active material or the precursor of the catalytically active material only in the outer part of the catalyst particle.

Chonnam National University | Date: 2015-12-31

Provided are a branched multi-peptide composition and a vaccine including the same. The branched multi-peptide vaccine according to the present invention is easy to be produced and utilized, thereby being easily applied to the treatment, and is capable of maintaining stable reaction in vivo, such that it is expected that the branched multi-peptide vaccine according to the present invention acts as an effective vaccine. Further, for the tumor antigen peptide, the present invention may select an antigen that is largely expressed in a malignant brain tumor. In addition, from now on, it is expected that tumor antigens having a large expression level may be analyzed depending on tumor characteristics of an individual patient, such that the branched multi-peptide vaccine according to the present invention may be utilized for producing personalized branched peptides and vaccines using the same.

The present invention relates to a gene delivery stent using titanium oxide thin film coating and a method for fabricating the gene delivery stent. The gene delivery stent according to the present invention may be loaded with a drug having anti-inflammatory and anti-thrombotic effects and simultaneously deliver a gene capable of inhibiting proliferation of vascular smooth muscle cells. Accordingly, late thrombosis and metal allergy may be reduced, and vascular restenosis in the stent region may be prevented, thereby making it possible to increase treatment effects of the bare metal stent.

Chonnam National University | Date: 2016-05-03

Provided is a composition for producing astringin among metabolites of polydatin, wherein the astringin may be mass-produced by oxidizing the polydatin using a CYP102A1 chimera and mutants thereof as a catalyst, the CYP102A1 chimera being produced by fusing a reductase domain of a wild-type CYP102A1 which is a bacterial cytochrome P450 enzyme, with a heme domain of a CYP102A1 mutant.

Li G.,Chonnam National University | Parmar M.,Chonnam National University | Kim D.,University of Texas at Dallas | Lee J.-B.,University of Texas at Dallas | And 2 more authors.
Lab on a Chip - Miniaturisation for Chemistry and Biology | Year: 2014

Galinstan has the potential to replace mercury-one of the most popular liquid metals. However, the easy oxidation of Galinstan restricts wide applicability of the material. In this paper, we report an effective reduction method for the oxidized Galinstan using gas permeable PDMS (polydimethlysiloxane)-based microfluidic channel. The complete study is divided into two parts-reduction of Galinstan oxide and behavior of reduced Galinstan oxide in a microfluidic channel. The reduction of Galinstan oxide is discussed on the basis of static as well as dynamic angles. The contact angle analyses help to find the extent of reduction by wetting characteristics of the oxide, to optimize PDMS thickness and to select suitable hydrochloric acid (HCl) concentration. The highest advancing angle of 155° and receding angle of 136° is achieved with 200 μm thick PDMS film and 37 wt% (weight percent) HCl solution. The behavior of reduced Galinstan oxide is analyzed in PDMS-based coplanar microfluidic channels fabricated using a simple micromolding technique. Galinstan in the microfluidic channel is surrounded by another coplanar channel filled with HCl solution. Due to the excellent permeability of PDMS, HCl permeates through the PDMS wall between the two channels (interchannel PDMS wall) and achieves a continuous chemical reaction with oxidized Galinstan. A Lab VIEW controlled syringe pump is used for observing the behavior of HCl treated Galinstan in the microfluidic channel. Further optimization of the microfluidic device has been conducted to minimize the reoxidation of reduced Galinstan oxide in the microfluidic channel. This journal is © 2014 The Royal Society of Chemistry.

Kim B.-H.,Chonnam National University | Yang K.S.,Chonnam National University | Ferraris J.P.,University of Texas at Dallas
Electrochimica Acta | Year: 2012

Polyacrylonitrile/poly(methyl methacrylate) (PMMA) fibers containing graphene are prepared by the electrospinning method, and hierarchical porous carbon nanofibers (CNFs) are obtained after subsequent heat treatment. The hierarchical porous CNFs have an improved structure and properties because of the increased surface area, unique nanotexture and increased electrical conductivity due to the dispersion of graphene. The carbonized fiber exhibits a high surface area (over 500 m 2 g -1) as result of the narrow ultramicro- and mesopore size distributions (centered at approximately 0.7 and 3.7 nm, respectively), and a broad mesopore size distribution ranging from 10 to 50 nm. The hierarchical pore structures are introduced by the evolution of small gas molecules during the decomposition of the PMMA during heat treatment. The highest specific capacitance of the CNFs is 128 F g -1, and the energy densities are 16.0-21.4 W h kg -1 in an aqueous solution and 75.0-58.2 W h kg -1 in an organic electrolyte over a power density range of 400-20,000 W kg -1. Under constant current charging/discharging at 1 mA cm -2 for 100 cycles, the stability of the CNFs in a 6 M KOH aqueous electrolyte decreases by ∼17% compared with the initial specific capacitance value. © 2012 Elsevier Ltd. All rights reserved.

Aravindan V.,Nanyang Technological University | Sundaramurthy J.,Ngee Ann Polytechnic | Suresh Kumar P.,Ngee Ann Polytechnic | Lee Y.-S.,Chonnam National University | And 2 more authors.
Chemical Communications | Year: 2015

In the present review, we describe the development of a high energy density LIB fabricated with all 1D nanofibers as the anode and cathode, as well as a separator-cum-electrolyte prepared by an electrospinning technique without compromising the power capability and cycle life. Such a unique assembly certainly enables realizing the advantages of using 1D nanostructures in practical LIBs, irrespective of the anode or cathode in the presence of gelled polyvinylidene fluoride-co-hexafluoropropylene as the separator-cum-electrolyte. Outstanding cycling profiles with high power densities were noted for all the configurations evaluated. This excellent performance opens up new avenues for the development of high performance Li-ion power packs with a long cycle life and high energy and power densities to drive zero emission transportation applications in the near future, and opens up new research activities in this field as well. © The Royal Society of Chemistry 2015.

Bae J.,National University of Singapore | Bae J.,ICFO - Institute of Photonic Sciences | Hwang W.-Y.,Chonnam National University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

We show a geometric formulation for minimum-error discrimination of qubit states that can be applied to arbitrary sets of qubit states given with arbitrary a priori probabilities. In particular, when qubit states are given with equal a priori probabilities, we provide a systematic way of finding optimal discrimination and the complete solution in a closed form. This generally gives a bound to cases when prior probabilities are unequal. Then it is shown that the guessing probability does not depend on detailed relations among the given states, such as the angles between them, but on a property that can be assigned by the set of given states itself. This also shows how a set of quantum states can be modified such that the guessing probability remains the same. Optimal measurements are also characterized accordingly, and a general method of finding them is provided. © 2013 American Physical Society.

Kim B.-H.,Daegu University | Yang K.S.,Chonnam National University | Yang D.J.,University of Texas at Dallas
Electrochimica Acta | Year: 2013

Mesopore-enriched activated carbon nanofiber (ACNF) mats are produced by incorporating vanadium(V)oxide (V2O5) into polyacrylonitrile (PAN) via electrospinning, and their electrochemical properties areinvestigated as an electrode in supercapacitors. The microstructures of the ACNFs (e.g., nanometer-sizediameter, high specific surface area, narrow pore size distribution, and tunable porosity) are changed,and the textural parameters are found to affect the electrochemical properties significantly through thedifferent V2O5 loadings and activation process. The V2O5/PAN-based ACNF electrodes with well-balancedmicro/mesoporosity having an optimal pore range for effective double layer formation in an organicmedium are expected to be useful electrode materials for supercapacitor applications. © 2013 Elsevier Ltd. All rights reserved.

Ahn C.-B.,Chonnam National University | Jeon Y.-J.,Jeju National University | Kim Y.-T.,Kunsan National University | Je J.-Y.,Chonnam National University
Process Biochemistry | Year: 2012

Angiotensin I converting enzyme (ACE) inhibitory peptides were produced from salmon byproduct proteins via enzymatic hydrolysis using Alcalase, flavourzyme, neutrase, pepsin, protamex and trypsin. Among them, Alcalase hydrolysate showed the highest ACE inhibitory activity, thus ACE inhibitory peptides were purified using consecutive chromatography. The purified ACE inhibitory peptides were identified to be Val-Trp-Asp-Pro-Pro-Lys-Phe-Asp (P1), Phe-Glu-Asp-Tyr-Val-Pro-Leu-Ser-Cys-Phe (P2), and Phe-Asn-Val-Pro-Leu-Tyr-Glu (P4) by time of flight-mass spectrometry/mass spectrometry (TOF-MS) analysis. The IC50 values against ACE activity were 9.10 μM (P1), 10.77 μM (P2) and 7.72 μM (P4). The inhibition mode of P1, P2 and P4 was analyzed using the Lineweaver-Burk plots, demonstrating P1 to be a non-competitive inhibitor, P2 and P4 having a mixed inhibition mode. Taken together, the salmon byproduct protein hydrolysate and/or its active peptides can be used in foods for its benefits against hypertension and related diseases. © 2012 Elsevier Ltd.

Lee S.-H.,Korea Advanced Institute of Science and Technology | Sridhar V.,Korea Advanced Institute of Science and Technology | Jung J.-H.,Korea Advanced Institute of Science and Technology | Jung J.-H.,University of Texas at Dallas | And 5 more authors.
ACS Nano | Year: 2013

In this study, we report a novel route via microwave irradiation to synthesize a bio-inspired hierarchical graphene-nanotube-iron three-dimensional nanostructure as an anode material in lithium-ion batteries. The nanostructure comprises vertically aligned carbon nanotubes grown directly on graphene sheets along with shorter branches of carbon nanotubes stemming out from both the graphene sheets and the vertically aligned carbon nanotubes. This bio-inspired hierarchical structure provides a three-dimensional conductive network for efficient charge-transfer and prevents the agglomeration and restacking of the graphene sheets enabling Li-ions to have greater access to the electrode material. In addition, functional iron-oxide nanoparticles decorated within the three-dimensional hierarchical structure provides outstanding lithium storage characteristics, resulting in very high specific capacities. The anode material delivers a reversible capacity of ∼1024 mA·h·g-1 even after prolonged cycling along with a Coulombic efficiency in excess of 99%, which reflects the ability of the hierarchical network to prevent agglomeration of the iron-oxide nanoparticles. © 2013 American Chemical Society.

Ha S.,Chonnam National University | Vankova R.,Academy of Sciences of the Czech Republic | Shinozaki K.,RIKEN | Tran L.-S.P.,RIKEN
Trends in Plant Science | Year: 2012

In plants, the cytokinin (CK) phytohormones regulate numerous biological processes, including responses to environmental stresses, via a complex network of CK signaling. By an unknown mechanism, stress signals are perceived and transmitted through the His-Asp phosphorelay, an important component of the CK signal transduction pathway, triggering CK-responsive genes. Because of the intensive crosstalk between CKs and abscisic acid (ABA), modulation of CK levels and their signal transduction affects both ABA-dependent and ABA-independent pathways, enabling plant adaptation to adverse conditions. This review presents our current understanding of the functions of CKs and CK signaling in the regulation of plant adaptation to stress. Biotechnological strategies based on the modulation of CK levels have been examined with the aim of stabilizing agriculture yields. © 2011 Elsevier Ltd.

Sexual health or erectile dysfunction (ED) state of the art guidelines provide a thorough overview of conventional prescription or other notable extrinsic treatment options. Yet, over the past 1015 years, a plethora of international researchers have established that individual and comprehensive lifestyle changes can prevent and potentially improve ED. We review the lifestyle evidence that should equate to grade A or level 1 evidence recommendations for ED. We also review the evidence for Panax ginseng, an over-the-counter (OTC) dietary supplement with a 35-year history of laboratory investigations, multiple positive randomized trials over approximately 15 years and several independent meta-analyses and systematic reviews. Perhaps it is time to at least discuss and even emphasize lifestyle and other non-conventional interventions in ED guidelines so that patients can explore a diversity of potentially synergistic choices with their physicians and can improve their quality and quantity of life. Ignoring the consistent, positive data on lifestyle modifications in ED guidelines, for example, is tantamount to ignoring diet and lifestyle changes to reduce the risk of or ameliorate cardiovascular diseases. © 2012 AJA, SIMM & SJTU. All rights reserved.

Vasudevan D.,National University of Singapore | Vasudevan D.,Novartis | Fu A.,University of California at Berkeley | Fu A.,Northwest University, China | And 3 more authors.
Plant Cell | Year: 2012

Cyclophilin38 (CYP38) is one of the highly divergent cyclophilins from Arabidopsis thaliana. Here, we report the crystal structure of the At-CYP38 protein (residues 83 to 437 of 437 amino acids) at 2.39-Å resolution. The structure reveals two distinct domains: an N-terminal helical bundle and a C-terminal cyclophilin b-barrel, connected by an acidic loop. Two N-terminal b-strands become part of the C-terminal cyclophilin b-barrel, thereby making a previously undiscovered domain organization. This study shows that CYP38 does not possess peptidyl-prolyl cis/trans isomerase activity and identifies a possible interaction of CYP38 with the E-loop of chlorophyll protein47 (CP47), a component of photosystem II. The interaction of CYP38 with the E-loop of CP47 is mediated through its cyclophilin domain. The N-terminal helical domain is closely packed together with the putative C-terminal cyclophilin domain and establishes a strong intramolecular interaction, thereby preventing the access of the cyclophilin domain to other proteins. This was further verified by protein-protein interaction assays using the yeast two-hybrid system. Furthermore, the non-Leucine zipper N-terminal helical bundle contains several new elements for protein-protein interaction that may be of functional significance. Together, this study provides the structure of a plant cyclophilin and explains a possible mechanism for autoinhibition of its function through an intramolecular interaction. © 2012 American Society of Plant Biologists. All rights reserved.

Agency: Cordis | Branch: FP7 | Program: CPCSA | Phase: INFRA-2007-1.2-03 | Award Amount: 49.02M | Year: 2008

A globally distributed computing Grid now plays an essential role for large-scale, data intensive science in many fields of research. The concept has been proven viable through the Enabling Grids for E-sciencE project (EGEE and EGEE-II, 2004-2008) and its related projects. EGEE-II is consolidating the operations and middleware of this Grid for use by a wide range of scientific communities, such as astrophysics, computational chemistry, earth and life sciences, fusion and particle physics. Strong quality assurance, training and outreach programmes contribute to the success of this production Grid infrastructure. \nBuilt on the pan-European network GANT2, EGEE has become a unique and powerful resource for European science, allowing researchers in all regions to collaborate on common challenges. Worldwide collaborations have extended its reach to the benefit of European science.\nThe proposed EGEE-III project has two clear objectives that are essential for European research infrastructures: to expand, optimize and simplify the use of Europes largest production Grid by continuous operation of the infrastructure, support for more user communities, and addition of further computational and data resources; to prepare the migration of the existing Grid from a project-based model to a sustainable federated infrastructure based on National Grid Initiatives. \nBy strengthening interoperable, open source middleware, EGEE-III will actively contribute to Grid standards, and work closely with businesses to ensure commercial uptake of the Grid, which is a key to sustainability. \nFederating its partners on a national or regional basis, EGEE-III will have a structuring effect on the European Research Area. In particular, EGEE-III will ensure that the European Grid does not fragment into incompatible infrastructures of varying maturity. EGEE-III will provide a world class, coherent and reliable European Grid, ensuring Europe remains at the forefront of scientific excellence.

Park R.J.,Chonnam National University | Moon J.D.,Chonnam National University
European Journal of Clinical Nutrition | Year: 2015

Background/Objectives:There is substantial interest in the health effects of coffee because it is the leading worldwide beverage after water. Existing literature on the connection between depression and coffee is scarce, and studies have yielded inconsistent results. The aim of this study was to examine the association between coffee consumption and depression in the Korean population.Subjects/Methods:We conducted a cross-sectional study in 10 177 Korean individuals aged 20-97 years who participated in the fifth Korean National Health and Nutrition Examination Survey. Consumption of coffee and depression were assessed using a questionnaire. Multiple logistic regression analysis was used to compute odds ratios (ORs) and 95% confidence intervals (CIs) for depression.Results:The lifetime prevalence of self-reported depression was 14.0% and that of self-reported clinical depression was 3.7%. After adjustment for potential confounders, the adjusted ORs for self-reported depression across coffee consumption categories were 1.00 (reference) for less than one cup/week, 0.84 (95% CI: 0.66, 1.07) for one to six cups/week, 0.63 (95% CI: 0.51, 0.79) for one cup/day, 0.69 (95% CI: 0.54, 0.88) for two cups/day and 0.58 (95% CI: 0.44, 0.76) for three or more cups/day (P for trend, <0.01). A similar association was observed for self-reported clinical depression, for which the multiple-adjusted ORs were 1.00 (reference) for less than one cup/week, 0.61 (95% CI: 0.40, 0.92) for one to six cups/week, 0.51 (95% CI: 0.34, 0.74) for one cup/day, 0.57 (95% CI: 0.39, 0.84) for two cups/day and 0.41 (95% CI: 0.24, 0.70) for three or more cups/day, respectively (P for trend, <0.01).Conclusions:These findings support a possible protective effect of coffee on the risk of depression. © 2015 Macmillan Publishers Limited.

Hessari P.,Kyungpook National University | Shin B.-C.,Chonnam National University
Computers and Mathematics with Applications | Year: 2013

A spectral collocation approximation of first-order system least squares for incompressible Stokes equations was analyzed in Kim et al. (2004) [12], and finite element approximations for incompressible Navier-Stokes equations were developed in Bochev et al. (1998,1999) [9,10]. The aim of this paper is to analyze the first-order system least-squares pseudo-spectral method for incompressible Navier-Stokes equations. The paper will be an extension of the result in Kim et al. (2004) [12] to the Navier-Stokes equations. Our least-squares functional is defined by the sum of discrete spectral norms of a first-order system of equations corresponding to the Navier-Stokes equations based on Legendre-Gauss-Lobatto points. We show its ellipticity and continuity over an appropriate product space, and spectral convergences of discretization errors are derived in the H1-norm and the L2-norm in each variable. Finally, we present some numerical examples. © 2013 Elsevier Ltd. All rights reserved.

Kumar Rai A.,Chonnam National University | Tuan Anh L.,Chonnam National University | Park C.-J.,Chonnam National University | Kim J.,Chonnam National University
Ceramics International | Year: 2013

Nickel oxide nanoparticles were synthesized via a simple and inexpensive microwave-assisted synthesis method within a fast reaction time of less than 20 min. The calcination of as-prepared precursor at 600 °C produces single phase nickel oxide. The lattice structure and morphology of the sample were investigated by X-ray diffraction, field-emission scanning electron microscopy and field-emission transmission electron microscopy. The particle size range of the nickel oxide nanoparticles varied from 50 to 60 nm. Nickel oxide nanoparticles exhibited good electrochemical performances as an anode material for lithium-ion batteries. The prepared nickel oxide anode revealed a large initial discharge capacity of 1111.08 mAh g-1 at 0.03 C rate and retained 80% of initial capacity (884.30 mAh g-1) after 20 cycles. Furthermore, at elevated rate of 3.7 C, the charge capacity of the nickel oxide electrode was as high as 253.1 mAh g-1, which was 35% greater than that of commercial bulk nickel oxide (188 mAh g-1). The enhancement of the electrochemical performance was attributed to the high specific surface area, good electric contact among the particles and easier lithium ion diffusion. © 2013 Elsevier Ltd and Techna Group S.r.l.

Jang H.-G.,Chonnam National University | Min H.-K.,Pohang University of Science and Technology | Lee J.K.,Pohang University of Science and Technology | Hong S.B.,Pohang University of Science and Technology | Seo G.,Chonnam National University
Applied Catalysis A: General | Year: 2012

The catalysis of methanol-to-olefin (MTO) reactions over SAPO-34 and ZSM-5 was strongly shown to depend on the crystallites sizes. Four samples (average size of 50-5000 nm) of each catalyst were characterized for shape, size, acidity and diffusion properties. Materials adsorbed and occluded on them during the reaction were directly monitored in situ by IR spectroscopy and analyzed ex situ by GC-MS after extraction. Crystallites of 200-500 nm showed the best conversions and lifetimes because of their large external surfaces and short diffusion lengths. SAPO-34 with the smallest crystallites (<150 nm) deactivated rapidly due to pore blocking by heavy coke deposits; similarly sized ZSM-5 exhibited low conversion due to the low number of strong Brönsted acid sites in its micropores. The adverse effects of the nanocrystallity of zeolite catalysts are discussed in terms of their framework topology, acidity, and diffusivity. © 2012 Elsevier B.V. All rights reserved.

Kim T.-Y.,Chonnam National University | Park S.-S.,Chonnam National University | Cho S.-Y.,Chonnam National University
Journal of Industrial and Engineering Chemistry | Year: 2012

In this study, epichlorohydrin cross-linked chitosan beads were used for the removal of Reactive Black 5 (RB 5) from aqueous solution. The adsorption of RB 5 onto the cross-linked chitosan beads was strongly pH dependent. The adsorption capacity of RB 5 onto the cross-linked chitosan beads increased with increasing temperature, indicating the endothermic nature of the adsorption process. The thermodynamic parameters, namely the Gibbs free energy, enthalpy and entropy of the RB 5 adsorption process were calculated. The kinetic parameters were measured in a batch adsorber to analyze the rate of adsorption of RB 5 onto the cross-linked chitosan beads. © 2012 The Korean Society of Industrial and Engineering Chemistry.

Lim W.-S.,Chonnam National University | Lee J.-W.,Chonnam National University
Bioresource Technology | Year: 2013

In this study, the effects of different acid catalysts and pretreatment factors on the hydrolysis of mixed softwood were investigated over a range of thermochemical pretreatments. Maleic, oxalic, and sulfuric acids were each used, under different pretreatment conditions. The most influential factor for fermentable sugar production in the dicarboxylic acid pretreatment of softwood was the pH. Reaction temperature was the next significant factor. However, during sulfuric acid pretreatment, fermentable sugar production was more dependent on reaction temperature, than time or pH. Enzymatic hydrolysis yields differed, depending on acid catalyst and pretreatment factor, regardless of lignin content in pretreated biomass. The highest enzymatic hydrolysis yield was found following maleic acid pretreatment, which reached 61.23%. The trend in enzymatic hydrolysis yields that were detected concomitantly with pretreatment condition or type of acid catalyst was closely related to the fermentable sugar production in the hydrolysate. © 2013.

Kim Y.-H.,Chonnam National University | Lee S.-M.,Korea forest Research Institute | Lee H.-W.,Chonnam National University | Lee J.-W.,Chonnam National University
Bioresource Technology | Year: 2012

We investigated the characteristics of torrefied yellow poplar (Liriodendron tulipifera) depending on reaction time (30. min) and temperature (240-280 °C). The thermogravimetric, grindability and calorific value of torrefied biomass were analyzed. As the torrefaction temperature increased, the carbon content of torrefied biomass increased from 49.50% to 54.42%, while the hydrogen and oxygen contents decreased from 6.09% to 5.65% and 28.71% to 26.61%, respectively. The highest calorific value was 1233. kJ/kg when torrefaction was performed at 280 °C for 30. min. An overall increase in energy density and decrease in mass and energy yield was observed with the increase in torrefaction temperature. The analysis of thermal decomposition demonstrated that the hemicelluloses contained in torrefied biomass decreased with increasing torrefaction temperature, whereas cellulose and lignin were only slightly affected. The grindability of torrefied biomass was significantly improved when torrefaction was performed at high temperature. Torrefaction of yellow poplar improved the chemical and physical fuel properties of the biomass. © 2012.

Kim J.,Inha University | Kim S.-N.,Inha University | Jang H.-G.,Chonnam National University | Seo G.,Chonnam National University | Ahn W.-S.,Inha University
Applied Catalysis A: General | Year: 2013

Metal organic framework (MOF) structures of UIO-66, UIO-66-NH2, Mg-MOF-74, MIL-101, CuBTC, ZIF-8, IRMOF-3, and MOF-5 having different acid/base properties were prepared and tested for their catalytic activity in the CO 2 cycloaddition to styrene epoxide using a high-pressure batch reactor. The high crystallinity and excellent textural properties of the prepared MOF materials were confirmed by XRD and the N2 adsorption-desorption isotherms at 77 K. Their catalytic cycloaddition activities were found to be well correlated with the Lewis acid/base distributions of the materials examined by NH3- and CO 2-TPD, respectively, such that the concurrent presence of Lewis acid and base sites were desirable for high catalytic activity. For a given catalyst weight, UIO-66-NH2 showed the best catalytic performance among the MOF samples tested with close to 100% selectivity to carbonate in chlorobenzene under relatively mild reaction conditions (2.0 MPa, 373 K). UIO-66-NH 2 could be reused 3 times without losing catalytic activity in a truly heterogeneous mode without structural deterioration, and it also exhibited excellent cycloaddition activities for different epoxide substrates as well. © 2012 Elsevier B.V.

Kim H.,KAIST | Kim H.,Chonnam National University | Jang M.,KAIST | Kang M.,Chonnam National University | Han Y.,KAIST
Human Molecular Genetics | Year: 2011

Embryonic stem cells (ESCs) maintain unique epigenetic states to maintain their pluripotency. Differentiation of ESCs into specialized cell types requires changes in these epigenetic states. However, the dynamics of epigenetic marks found in hESCs during differentiation are poorly understood. Here, we report the variation in the dynamics of epigenetic modifications associated with the expression of lineage-specific genes during differentiation of hESCs to hepatocytes in vitro. The promoter regions of pluripotency marker genes characterized by permissive histone marks such as trimethylation of H3 at lysine 4 (H3K4me3) and acetylation of H3 at lysine 9 (H3K9ac) in hESCs were instead enriched with repressive histone marks such as dimethylation of H3 at lysine 9 (H3K9me2), trimethylation of H3 at lysine 9 (H3K9me3) and trimethylation of H3 at lysine 27 (H3K27me3) during differentiation to hepatocytes. Interestingly, expression of definitive endoderm marker genes containing bivalent and non-bivalent domains may be modulated by a marked reduction in H3K27me3 and a significant enhancement of permissive marks such as H3K4me3 and H3K9ac during hESC differentiation. Expression of hepatocyte marker genes regulated by histone modifications was similar to that of pluripotency marker genes. Our findings provide insight into the epigenetic mechanisms regulating expression of developmental genes. Of particular interest, they may be differentially regulated either in a bivalent or non-bivalent domain manner during hESC differentiation. © The Author 2010. Published by Oxford University Press. All rights reserved.

Lee H.-J.,Chonnam National University | Lim W.-S.,Chonnam National University | Lee J.-W.,Chonnam National University
Journal of Industrial and Engineering Chemistry | Year: 2013

In this study, the removal efficiency of fermentation inhibitors in a lignocellulosic hydrolysate by electrodialysis (ED) and the ethanol performance of ED-treated hydrolysate were investigated. The fermentable sugars and inhibitors concentrations in the hydrolysate differed significantly depending on the kind of biomass and acid catalysts. In the mixed hardwood, acetic acid and furfural in the hydrolysate were high as 8.41-8.57. g/L and 2.68-4.23. g/L, respectively, but 5-hydroxymethylfurfural (HMF) concentration was relatively low compared with that of mixed softwood. The ED process showed the high effectiveness for removing acetic acid and total phenolic compounds in the hydrolysate without loss of fermentable sugars. However, most of the HMF and furfural remained in the hydrolysate after ED. Ethanol fermentation was not completed in untreated and mixed hardwood ED-treated hydrolysates due to the high concentration of furfural. Meanwhile, ethanol fermentation was successfully performed in a mixed softwood ED-treated hydrolysate pretreated with dicarboxylic acid. The maximum ethanol concentration attained after fermentation with an initial fermentable sugar level of 27.78. g/L was 10.12. g/L after 48. h. © 2013.

Choi I.S.,Chonnam National University | Wi S.G.,Chonnam National University | Kim S.-B.,Chonnam National University | Bae H.-J.,Chonnam National University
Bioresource Technology | Year: 2012

Coffee residue waste (CRW), which is produced after coffee extraction for coffee powder and instant coffee preparation, is a primary industrial waste. In this study, the use of CRW for bioethanol production was evaluated. The carbohydrate content of CRW was analyzed for fermentable sugars such as glucose, galactose, and mannose, which can be fermented by Saccharomyces cerevisiae. Pretreatment at a pressure of 1.47. MPa for 10. min with popping pretreatment was required to increase enzymatic hydrolysis. CRW was well hydrolyzed following popping pretreatment at 1.47. MPa. The enzymatic conversion rate of CRW to fermentable sugars was 85.6%. Ethanol concentration and yield (based on sugar content) following enzymatic hydrolysis after simultaneous saccharification and fermentation were 15.3. g/L and 87.2%, respectively. © 2012 Elsevier Ltd.

Lee Y.J.,Hanyang University | Lee J.-H.,Hanyang University | Cho H.-J.,Hanyang University | Kim H.K.,Chonnam National University | And 2 more authors.
Biomaterials | Year: 2013

The development of ideal barrier membranes with appropriate porosity and bioactivity is essential for the guidance of new bone formation in orthopedic and craniomaxillofacial surgery. In this study, we developed bioactive electrospun fibers based on poly (lactide-co-glycolic acid) (PLGA) by immobilizing bone-forming peptide 1 (BFP1) derived from the immature region of bone morphogenetic protein 7(BMP7). We exploited polydopamine chemistry for the immobilization of BFP1; polydopamine (PD) was coated on the electrospun PLGA fibers, on which BFP1 was subsequently immobilized under weakly basic conditions. The immobilization of BFP1 was verified by characterizing the surface chemical composition and quantitatively measured by fluorescamine assay. The immobilization of BPF1 on the electrospun fibers supported the compact distribution of collagen I and the spreading of human mesenchymal stem cells (hMSCs). SEM micrographs demonstrated the aggregation of globular mineral accretions, with significant increases in ALP activity and calcium deposition when hMSCs were cultured on fibers immobilized with BFP1 for 14 days. We then implanted the prepared fibers onto mouse calvarial defects and analyzed bone formation after 2 months. Semi-quantification of bone growth from representative X-ray images showed that the bone area was approximately 20% in the defect-only group, while the group implanted with PLGA fibers showed significant improvements of 44.27±7.37% and 57.59±15.24% in the groups implanted with PD-coated PLGA and with BFP1-coated PLGA, respectively. Based on these results, our approach may be a promising tool to develop clinically-applicable bioactive membranes for guided bone regeneration.". © 2013 Elsevier Ltd.

Kang W.,Chonnam National University | Choi B.,Chonnam National University | Kim H.,Chonnam National University
Journal of Industrial and Engineering Chemistry | Year: 2013

The purpose of this study is to investigate the characteristics of the simultaneous removal of PM and NO. x on the CuNb-ZSM-5 SCR/DPF catalysts coated onto DPF substrate. NO. x conversion by the CuNb-ZSM-5 catalyst was higher than those by Cu- or Fe-ZSM-5 catalysts. NO. x conversion of the SCR/DPF catalyst with a wall-flow (plugged) was considerably lower under 450 °C than that of the SCR/DPF catalyst with a channel-flow (unplugged). The de-NO. x performance of the SCR/DPF catalyst coated with CuNb-ZSM-5 was highest among the catalysts examined. SCR/DPF catalyst coated with CuNb-ZSM-5 had superior PM oxidation performance compared to the other SCR/DPF catalysts. © 2013 The Korean Society of Industrial and Engineering Chemistry.

Lee J.,Chonnam National University | Kim Y.,Chungbuk National University
Journal of Industrial and Engineering Chemistry | Year: 2012

Four zirconium complexes containing fully deprotonated 2-(2H-benzo[d][1,2,3]triazol-2-yl)-4,6-di- tert-pentylphenol were used as catalysts for the polymerization of ethylene. In the presence of methylalumoxane (MAO) as a cocatalyst, the precursors were highly active for polyethylene with bimodal or multimodal molecular weight distribution. © 2011 The Korean Society of Industrial and Engineering Chemistry.

Ahmed M.S.,Chonnam National University | Kim D.,Chonnam National University | Jeon S.,Chonnam National University
Electrochimica Acta | Year: 2013

A carbon nanostructure has fabricated from covalently grafted platinum (Pt) to multi walled carbon nanotube (MWCNT) with the assistance of sulfur atom on the MWCNT's sidewall, MWCNT-S-Pt. The MWCNT-S-Pt displays an excellent electrocatalytic performance for oxygen reduction reaction (ORR) than that of an unbonded Pt to MWCNT, MWCNT/Pt. Here we describe a comparative study of the ORR on two MWCNT-supported Pt-based catalysts in aqueous acidic electrolyte. Both MWCNT-S-Pt and MWCNT/Pt catalysts have the compositions of 1.03 and 2.18 at% Pt, respectively. For the characterization, the bonding features have confirmed by the X-ray photoelectron spectroscopic (XPS) and electron microscopy have used to determine the size and shape as well as the distribution of the particle on both catalysts. Electrochemical measurements have performed using the cyclic voltammetry and hydrodynamic voltammetry methods in 0.1 mol l-1 HClO4 solution. Kinetic analysis in comparison to unbonded MWCNT/Pt a significant enhancement for the covalently bonded MWCNT-S-Pt has been found. The MWCNT/Pt is unstable at electrode potentials for long term use than that of MWCNT-S-Pt. Ring-current collection measurements for peroxide indicate MWCNT-S-Pt catalyst has a less peroxide yield. © 2012 Elsevier Ltd.

Kim B.-H.,Chonnam National University | Yang K.S.,Chonnam National University
Electrochimica Acta | Year: 2013

Carbon nanofibers (CNFs) containing boron and nitrogen are prepared from polyacrylonitrile and boron trioxide (B2O3) by using simple electrospinning. The B2O3 introduction into a PAN solution causes a porous structure with stabilized [O]BN functional groups to develop in the processes of stabilization and carbonization. The pore structure and the functional groups such as B atoms and [O]BN introduce synergistic effects by not only increasing the power density but also the energy density, as shown by the results. The energy storage capabilities of the electrode prepared from 20 wt% B2O3 added to the PAN solution are as follows: a capacitance of 184.0 F g-1 and an energy density of 18.7-25.2 Wh kg-1 in the respective power density range of 400-10,000 W kg-1 in 6 M KOH electrolyte. Hence, these CNFs exhibit a very promising potential as electrode materials for electrical double-layer capacitors due to their unique microstructure and proper proportion of heteroatoms. © 2012 Elsevier Ltd. All rights reserved.

Jeong J.-T.,Chonnam National University
Theoretical and Computational Fluid Dynamics | Year: 2012

The free-surface shape and cusp formation are analyzed by considering a viscous flow arising from the superposition of a source/sink and vortex below the free surface where the strength of the source and vortex are arbitrary. In the analysis, Stokes' approximation is used and surface tension effects are included, but gravity is neglected. The solution is obtained analytically by using conformal mapping and complex function theory. From the solution, shapes of the free surface are obtained, and the formation of a cusp on the free surface is discussed. Above some critical capillary number with a sink, the free-surface shape becomes singular and an apparent cusp should form on the free surface below a real fluid. On the other hand, no cusp would occur for sources of zero or positive strength. Typical streamline patterns are also shown for some capillary numbers. As the capillary number vanishes, the solution is reduced to a linearized potential flow solution. © Springer-Verlag 2011.

Kalubarme R.S.,Chonnam National University | Jadhav H.S.,Chonnam National University | Park C.-J.,Chonnam National University
Electrochimica Acta | Year: 2013

Manganese oxide (MnO2) powders with various nano structures were prepared using MnSO4 as a precursor through hydrothermal method. Manganese oxides with needles, rods and flakes structure were formed depending on oxidizer used. The flakes-shaped MnO2 exhibited the higher capacitance values than other structures, both in aqueous and organic electrolytes. The charge storage mechanism observed in aqueous electrolyte is mixed type of charge insertion-extraction and surface adsorption mechanism while that in organic electrolyte is insertion-extraction. The higher specific capacitance of 342 F g-1 in NaOH, 429 F g-1 in LiClO 4 and 455 F g-1 in LiPF6 was observed for the flakes-shaped MnO2 electrode. © 2012 Elsevier Ltd.

Kim T.H.,Chonnam National University
International journal of nanomedicine | Year: 2011

Celecoxib, a cyclo-oxygenase (COX)-2 inhibitor, has been reported to mediate growth inhibitory effects and to induce apoptosis in various cancer cell lines. In this study, we examined the potential effects of celecoxib on glioma cell proliferation, migration, and inhibition of COX-2 expression in vitro. Celecoxib was incorporated into poly DL-lactide-co-glycolide (PLGA) nanoparticles for antitumor drug delivery. PLGA nanoparticles incorporating celecoxib had spherical shapes and their particle sizes were in the range of 50-200 nm. Drug-loading efficiency was not significantly changed according to the solvent used, except for acetone. Celecoxib was released from the PLGA nanoparticles for more than 2 days, and the higher the drug content, the longer the duration of drug release. PLGA nanoparticles incorporating celecoxib showed cytotoxicity against U87MG tumor cells similar to that of celecoxib administered alone. Furthermore, celecoxib did not affect the degree of migration of U87MG cells. PLGA nanoparticles incorporating celecoxib showed dose-dependent cytotoxicity similar to that of celecoxib alone in C6 rat glioma cells. Western blot assay of the C6 cells showed that neither celecoxib alone nor PLGA nanoparticles incorporating celecoxib affected COX-2 expression. PLGA nanoparticles incorporating celecoxib had antitumor activity similar to that of celecoxib alone, even though these particles did not affect the degree of migration or COX-2 expression in the tumor cells.

Lee H.Y.,Chonnam National University | Byeon Y.,Chonnam National University | Back K.,Chonnam National University
Journal of Pineal Research | Year: 2014

Melatonin plays pleiotropic roles in both animals and plants. The possible role of melatonin in plant innate immune responses was recently discovered. As an initial study, we employed Arabidopsis to determine whether melatonin is involved in defense against the virulent bacterial pathogen Pseudomonas syringae DC3000. The application of a 10 μm concentration of melatonin on Arabidopsis and tobacco leaves induced various pathogenesis-related (PR) genes, as well as a series of defense genes activated by salicylic acid (SA) and ethylene (ET), two key factors involved in plant defense response, compared to mock-treated leaves. The induction of these defense-related genes in melatonin-treated Arabidopsis matched an increase in resistance against the bacterium by suppressing its multiplication about ten-fold relative to the mock-treated Arabidopsis. Like melatonin, N-acetylserotonin also plays a role in inducing a series of defense genes, although serotonin does not. Furthermore, melatonin-induced PR genes were almost completely or partially suppressed in the npr1, ein2, and mpk6 Arabidopsis mutants, indicative of SA and ET dependency in melatonin-induced plant defense signaling. This suggests that melatonin may be a novel defense signaling molecule in plant-pathogen interactions. © 2014 John Wiley & Sons A/S.

Park S.C.,Chonnam National University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011

Recently the CMS Collaboration at the LHC reported "the first direct limit on black hole production at a particle accelerator" using a data sample corresponding to an integrated luminosity of 35 pb-1 of pp collision at a center of mass energy of 7 TeV (Khachatryan et al., 2011) [1]. Even though the result has a strong impact on future searches, the interpretation lacks enough theoretical support. In this Letter, we show that the parameter range which was considered by the CMS Collaboration is actually out of the validity range of semi-classical black hole picture so that the Monte Carlo simulation result which was crucially used in the analysis still needs further solid scientific basis. © 2011 Elsevier B.V.

Park S.H.,Chonnam National University | Lee C.S.,Hanyang University
Energy Conversion and Management | Year: 2014

From the perspectives of environmental conservation and energy security, dimethyl-ether (DME) is an attractive alternative to conventional diesel fuel for compression ignition (CI) engines. This review article deals with the application characteristics of DME in CI engines, including its fuel properties, spray and atomization characteristics, combustion performance, and exhaust emission characteristics. We also discuss the various technological problems associated with its application in actual engine systems and describe the field test results of developed DME-fueled vehicles. Combustion of DME fuel is associated with low NOx, HC, and CO emissions. In addition, PM emission of DME combustion is very low due to its molecular structure. Moreover, DME has superior atomization and vaporization characteristics than conventional diesel. A high exhaust gas recirculation (EGR) rate can be used in a DME engine to reduce NOx emission without any increase in soot emission, because DME combustion is essentially soot-free. To decrease NOx emission, engine after-treatment devices, such as lean NOx traps (LNTs), urea-selective catalytic reduction, and the combination of EGR and catalyst have been applied. To use DME fuel in automotive vehicles, injector design, fuel feed pump, and the high-pressure injection pump have to be modified, combustion system components, including sealing materials, have to be rigorously designed. To use DME fuel in the diesel vehicles, more research is required to enhance its calorific value and engine durability due to the low lubricity of DME, and methods to reduce NOx emission are also required. © 2014 Elsevier Ltd. All rights reserved.

Lee J.S.,Chonnam National University | Arunkumar P.,Chonnam National University | Kim S.,LG Innotek | Lee I.J.,LG Innotek | And 2 more authors.
Optics Letters | Year: 2014

The white light-emitting diode (WLED) is a state-of-the-art solid state technology, which has replaced conventional lighting systems due to its reduced energy consumption, its reliability, and long life. However, the WLED presents acute challenges in device engineering, due to its lack of color purity, efficacy, and thermal stability of the lighting devices. The prime cause for inadequacies in color purity and luminous efficiency is the spectral overlapping of red components with yellow/green emissions when generating white light by pumping a blue InGaN chip with yellow YAG:Ce3+ phosphor, where red phosphor is included, to compensate for deficiencies in the red region. An innovative strategy was formulated to resolve this spectral overlapping by alternatively arranging phosphor-in-glass (PiG) through cutting and reassembling the commercial red CaAlSiN3:Eu2+ and green Lu3Al5O12:Ce3+ PiG. PiGs were fabricated using glass frits with a low softening temperature of 600°C, which exhibited excellent thermal stability and high transparency, improving life time even at an operating temperature of 200°C. This strategy overcomes the spectral overlapping issue more efficiently than the randomly mixed and patented stacking design of multiple phosphors for a remote-type WLED. The protocol for the current design of PiG possesses excellent thermal and chemical stability with high luminous efficiency and color purity is an attempt to make smarter solid state lighting for highpowered remote-type white light-emitting devices. © 2014 Optical Society of America.

Bang Y.,Chonnam National University | Bang Y.,Asia Pacific Center for Theoretical Physics
New Journal of Physics | Year: 2014

The electron band around the M point in the compound, which is completely lifted up above the Fermi level for and hence its Fermi surface (FS) disappears, can still play the role of the main pairing resource by exchanging inter-band repulsive interaction with the main hole band (h1) around the point. This hidden electron band, which develops the superconducting order parameter (OP) but has no FS, displays a shadow gap feature which is easily detected by various experimental probes such as angle-resolved photoemission spectroscopy (ARPES) and tunneling measurements. We also show that the formation of the nodal gap with symmetry on another hole pocket (h2) around the point with a larger FS is stabilized due to the balance of the inter-band repulsive interactions from the main hole band (h1) with the OP , and the hidden electron band with the OP . © 2014 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

Ahmed M.,Chonnam National University | Akter M.S.,Chonnam National University | Eun J.-B.,Chonnam National University
Journal of the Science of Food and Agriculture | Year: 2010

BACKGROUND: Purple sweet potato flour could be used to enhance food products through colour, flavour and nutrients. Purple sweet potato flour has not yet been prepared with maltodextrin and amylase treatment using spray drying. Thus, the investigation was to evaluate the effect of various levels of maltodextrin (30 and 50 g kg-1 w/v), amylase (3 and 7 g kg-1 puree) and combined with maltodextrin and amylase on the physicochemical, functional and antioxidant capacity of spray dried purple sweet potato flours. RESULTS: Amylase and amylase with maltodextrin-treated flours had a higher anthocyanin and total phenolic content than the control and maltodextrin-treated flours. However, the antioxidant capacity was higher in the control and maltodextrin-treated flours compared to the amylase and amylase with maltodextrin-treatedflours. The control had a higher water absorption index and lower water solubility index compared to the maltodextrin and combined with amylase and maltodextrin-treated flours. On the other hand, maltodextrin increased whereas α-amylase decreased the glass transition temperature. With respect to morphology, the particles of amylase-treated flours were smaller than the control and maltodextrin-treated flours. CONCLUSION: The results showed that good quality flour could be prepared by combining 30 g kg-1 maltodextrin and 7 g kg-1 amylase treatment. © 2009 Society of Chemical Industry.

Park R.J.,Chonnam National University | Moon J.D.,Chonnam National University
Clinical Otolaryngology | Year: 2014

Objectives: The aim of this study was to examine the association between tinnitus and several potential risk factors in Korean population. Design: A cross-sectional study. Setting: Based on data from the fifth Korean National Health and Nutrition Examination Survey. Participants: The study included 10 061 Korean individuals. Main outcome measures: Tinnitus was assessed by using a questionnaire, and otorhinolaryngologic examination was conducted. Risk factors associated with tinnitus were evaluated using a multiple logistic regression analysis. Results: Of the 10 061 participants ranging from 20 to 97 years old, the overall prevalence of any tinnitus was 21.4% and annoying tinnitus was 7.3%. In a multivariable logistic regression model, the following factors were associated with having tinnitus: occupational noise exposure [any tinnitus, odd ratio (OR) = 1.34; annoying tinnitus, OR = 1.47], non-occupational noise exposure (any tinnitus, OR = 1.48; annoying tinnitus, OR = 2.02), hearing impairment (any tinnitus, OR = 2.27; annoying tinnitus, OR = 3.61), chronic otitis media (any tinnitus, OR = 1.53; annoying tinnitus, OR = 1.36), chronic rhinosinusitis (any tinnitus, OR = 1.38; annoying tinnitus, OR = 1.38), temporomandibular disorder (any tinnitus, OR = 1.69; annoying tinnitus, OR = 1.90), depression (any tinnitus, OR = 1.44; annoying tinnitus, OR = 1.70), and higher stress level (any tinnitus, OR = 1.28; annoying tinnitus, OR = 1.76). Conclusions: These results suggest that tinnitus is common in Korea and may be associated with some avoidable risk factors. © 2014 John Wiley & Sons Ltd.

Lee S.B.,Chonnam National University | Suh M.C.,Chonnam National University
Plant and Cell Physiology | Year: 2015

The aerial parts of all land plants are covered with hydrophobic cuticular wax layers that act as the first barrier against the environment. The MYB94 transcription factor gene is expressed in abundance in aerial organs and shows a higher expression in the stem epidermis than within the stem. When seedlings were subjected to various treatments, the expression of the MYB94 transcription factor gene was observed to increase approximately 9-fold under drought, 8-fold for ABA treatment and 4-fold for separate NaCl and mannitol treatments. MYB94 harbors the transcriptional activation domain at its C-terminus, and fluorescent signals from MYB94:enhanced yellow fluorescent protein (eYFP) were observed in the nucleus of tobacco epidermis and in transgenic Arabidopsis roots. The total wax loads increased by approximately 2-fold in the leaves of the MYB94-overexpressing (MYB94 OX) lines, as compared with those of the wild type (WT). MYB94 activates the expression of WSD1, KCS2/DAISY, CER2, FAR3 and ECR genes by binding directly to their gene promoters. An increase in the accumulation of cuticular wax was observed to reduce the rate of cuticular transpiration in the leaves of MYB94 OX lines, under drought stress conditions. Taken together, a R2R3-type MYB94 transcription factor activates Arabidopsis cuticular wax biosynthesis and might be important in plant response to environmental stress, including drought. © 2014 The Author.

Hu C.-Y.,Chonnam National University | Lee K.-B.,Chonnam National University | Song E.-K.,Chonnam National University | Kim M.-S.,Chonnam National University | Park K.-S.,Chonnam National University
American Journal of Sports Medicine | Year: 2013

Background: The modified Broström procedure is frequently used to treat chronic lateral ankle instability. There are 2 common methods of the modified Broström procedure, which are the bone tunnel and suture anchor techniques. Purpose: To compare the clinical outcomes of the modified Broström procedure using the bone tunnel and suture anchor techniques. Study Design: Cohort study; Level of evidence, 2. Methods: Eighty-one patients (81 ankles) treated with the modified Broström procedure for chronic lateral ankle instability constituted the study cohort. The 81 ankles were divided into 2 groups, namely, a bone tunnel technique (BT group; 40 ankles) and a suture anchor technique (SA group; 41 ankles). The Karlsson score, American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, anterior talar translation, and talar tilt angle were used to evaluate clinical and radiographic outcomes. The BT group consisted of 32 men and 8 women with a mean age of 34.8 years at surgery and a mean follow-up duration of 34.2 months. The SA group consisted of 33 men and 8 women with a mean age of 33.3 years at surgery and a mean followup duration of 32.8 months. Results: Mean Karlsson scores improved significantly from 57.0 points preoperatively to 94.9 points at final follow-up in the BT group and from 59.9 points preoperatively to 96.4 points at final follow-up in the SA group. Mean AOFAS scores also improved from 64.2 points preoperatively to 97.8 points at final follow-up in the BT group and from 70.3 points preoperatively to 97.4 points at final follow-up in the SA group. Mean anterior talar translations in the BT group and SA group improved from 9.0 mm and 9.2 mm preoperatively to 6.5 mm and 6.8 mm at final follow-up, respectively. Mean talar tilt angles were 12.0° in the BT group and 12.5° in the SA group preoperatively and 8.8° at final follow-up for both groups. No significant differences were found between the 2 groups in terms of the Karlsson score, AOFAS score, anterior talar translation, and talar tilt angle. Conclusion: The bone tunnel and suture anchor techniques of the modified Broström procedure showed similar good functional and radiographic outcomes. Both techniques appear to be effective and reliable methods for the treatment of chronic lateral ankle instability. © 2013 The Author(s).

Park S.Y.,Chonnam National University
The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi | Year: 2010

Heparin and/or insulin stimulate lipoprotein lipase and are known to decrease serum triglyceride level. However, their efficacy in hypertriglyceridemia-induced acute pancreatitis in nondiabetic patients is not well documented. We report a case of hypertriglyceridemia-induced pancreatitis in 43-year-old nondiabetic woman in whom treatment with insulin was accompanied by reduction in serum triglyceride level and the resolution of pancreatitis. She presented to the emergency department with abdominal pain and biochemical evidence of acute pancreatitis. Her medical history was unremarkable. There was no history of alcohol consumption, and biliary imaging was not remarkable. Subsequent laboratory investigation revealed marked hypertriglyceridemia (1,951 mg/dL), impaired fasting glucose, and normal HbAlc level. The Ransons score and APATCH II score were 1 and 4. Abdominal CT showed diffuse enlargement of pancreas, peripancreatic fat infiltration, and multiple fluid collections around the pancreas. We treated the patient with the infusion of 5% dextrose and 1.5 unit/hr regular insulin to reduce serum triglyceride level. The level of serum triglyceride was decreased to 305 mg/dL on day 5. During the remainder of hospitalization, her clinical symptoms and laboratory values gradually improved.

Cheung K.,National Tsing Hua University | Cheung K.,Konkuk University | Lee J.S.,Chonnam National University | Tseng P.-Y.,National Tsing Hua University
Journal of High Energy Physics | Year: 2014

We perform global fits to general two-Higgs doublet models (2HDMs) with generalized couplings using the most updated data from ATLAS, CMS, and Tevatron. We include both scenarios with CP-conserving and CP-violating couplings. By relaxing the requirement on the discrete symmetries that are often imposed on the Yukawa couplings, we try to see which of the 2HDMs is preferred. We found that (i) Higgcision in 2HDMs can be performed efficiently by using only 4 parameters including the charged Higgs contributions to the Higgs couplings to two photons, (ii) the differences among various types of 2HDMs are very small with respect to the chi-square fits, (iii) tan β is constrained to be small, (iv) the p-values for various fits in 2HDMs are worse than that of the standard model. Finally, we put emphasis on our findings that future precision measurements of the Higgs coupling to the scalar top-quark bilinear {C u S) and tan β may endow us with the discriminating power among various types of 2HDMs especially when Cu S deviates from its SM value 1. © 2014 The Author(s).

Yang S.J.,Chonnam National University | Lim Y.,Kyung Hee University
Metabolism: Clinical and Experimental | Year: 2014

Objective Resveratrol (RSV) regulates NAD bioavailability and sirtuin-related metabolism, which relates to aging, metabolic syndrome and non-alcoholic fatty liver disease. The purpose of this study was to investigate the effects of resveratrol on hepatic metaflammation in a rodent model of high-fat (HF) diet-induced obesity (DIO). Materials/Methods DIO was induced in a subset of mice given an HF diet (45% kcal fat). After 6 weeks of HF diet feeding, RSV was delivered via an osmotic pump for 4 weeks. The experimental groups were as follows: 1) lean control fed with a standard diet, 2) HF diet-induced obese control, and 3) HF-RSV (8 mg/kg/day). After 4 weeks of each treatment, blood and liver tissues were collected and the indices of glucose control, serum and liver triglyceride (TG), sirtuin pathway, inflammation, and NOD-like receptor family, pryin domain containing 3 (NLRP3) inflammasome were analyzed. Results Body weight and food intake were not altered by administering resveratrol. Glucose control was impaired, and serum and liver TG levels were increased by the HF diet. Hepatic inflammation was aggravated in mice fed with the HF diet, as shown by the increased levels of the pro-inflammatory markers interleukin-1 (IL-1), IL-6 and tumor necrosis factor-alpha in the liver. However, resveratrol administration significantly improved glucose control, and serum and liver TG contents. Also, resveratrol treatment reduced the levels of the pro-inflammatory markers. These improvements were accompanied by alterations in sirtuin pathway and NLRP3 inflammasome activation. Conclusion These results demonstrate that resveratrol ameliorates hepatic metaflammation, accompanied by alterations in NLRP3 inflammasome. © 2014 Elsevier Inc. All rights reserved.

Kang S.-R.,Chonnam National University
Clinical Nuclear Medicine | Year: 2016

ABSTRACT: Symmetric bifrontal uptake of bone-seeking agents is usually considered as the main feature of hyperostosis frontalis interna in postmenopausal elderly women. This finding is not uncommon in elderly women because of the change in their hormonal level. However, in the present case, a 66-year-old woman with intra-axial brain metastases of breast cancer showed symmetric bifrontal uptake on bone scintigraphy. Therefore, symmetric bifrontal uptake should not always be considered as a definite indicator of hyperostosis frontalis interna. Further evaluation such as SPECT/CT is needed for evaluation of brain metastases especially in cancer patients. Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.

Unnithan A.R.,Chonbuk National University | Gnanasekaran G.,Chonnam National University | Sathishkumar Y.,Chonbuk National University | Lee Y.S.,Chonbuk National University | Kim C.S.,Chonbuk National University
Carbohydrate Polymers | Year: 2014

In this study, an antibacterial electrospun nanofibrous scaffolds with diameters around 400-700 nm were prepared by physically blending polyurethane (PU) with two biopolymers such as cellulose acetate (CA) and zein. Here, PU was used as the foundation polymer, was blended with CA and zein to achieve desirable properties such as better hydrophilicity, excellent cell attachment, proliferation and blood clotting ability. To prevent common clinical infections, an antimicrobial agent, streptomycin sulfate was incorporated into the electrospun fibers and its antimicrobial ability against the gram negative and gram positive bacteria were examined. The interaction between fibroblasts and the PU-CA and PU-CA-zein-drug scaffolds such as viability, proliferation, and attachment were characterized. PU-CA-zein-drug composite nanoscaffold showed enhanced blood clotting ability in comparison with pristine PU nanofibers. The presence of CA and zein in the nanofiber membrane improved its hydrophilicity, bioactivity and created a moist environment for the wound, which can accelerate wound recovery. © 2013 Elsevier Ltd.

Lim S.K.,Chonnam National University | Park S.H.,Chonnam National University
Life Sciences | Year: 2012

Aims: We examined renal kallikrein-kinin system (KKS) apoptosis and its related signaling pathway in rat podocytes. In addition, we studied the relationship of cannabinoid receptor 1 (CB1R) with high glucose and BK receptors. Main methods: Cell viability was determined by an MTT assay and apoptosis by DNA fragmentation assay, while gene expression was investigated by RT-PCR. Protein expression was analyzed by Western blot analysis. A chemical inhibitor or siRNA transfection was used to inhibit B1R, B2R, and CB 1R signaling. Key findings: High glucose (25 mM) treatment decreased cell viability and increased DNA fragmentation. High glucose-induced DNA fragmentation and PARP and caspase-3 activations were blocked by both [des-Arg10]-HOE 140 (a B1R antagonist) and HOE 140 (a B2R antagonist). High glucose also increased Akt phosphorylation, ER stress-related protein expression, and NF-κB/I-κB phosphorylation in podocytes, which was blocked by both [des-Arg10]-HOE 140 and HOE 140. In addition, B1R and B2R siRNA transfections prevented high glucose-induced Akt and NF-κB activations in rat podocytes. Moreover, AM251 (a CB1R antagonist) treatment and CB1R siRNA transfection blocked the high glucose-induced stimulation of BK receptor expression, Akt activation, and NF-κB activation. Significance: Our study suggests that hyperglycemia induces apoptosis via the stimulation of B1R and B2R expression through CB 1R activation in rat podocytes in vitro, which is associated with the development of diabetic nephropathy. © 2012 Published by Elsevier Inc.

Lee C.,Chonnam National University | Lim C.,Chonnam National University
Earth and Planetary Science Letters | Year: 2014

The pulse-like adakite eruption in Mt. Abukuma, northeastern Japan at ~16 Ma has been considered peculiar because the subducting Pacific slab was too old to have been melted. Recent studies suggested that the injection of hot asthenospheric mantle as a temporal temperature anomaly into the corner of the mantle wedge was responsible for partial melting of the subducting slab, producing adakitic magma. However, the pulse-like and localized eruption of the Abukuma adakite poses a problem to the above model because rollback of the Pacific plate for ~10 Myr should have resulted in injection of the hot asthenospheric mantle into the corner of the mantle wedge along northeastern Japan, Sikhote-Alin, and Sakhalin. In addition, no quantitative examination of the interaction between the hot asthenospheric mantle and cold subducting Pacific plate has been performed. In this study, we used a series of two-dimensional kinematic-dynamic numerical subduction models to evaluate slab melting by the injection of a short-term temperature anomaly into the mantle wedge. Our model calculations show that injection of the short-term temperature anomaly into the corner of the mantle wedge resulted in slab melting at ~17 Ma, but that the duration of injection should be <5 Myr to comply with the pulse-like eruption of the Abukuma adakite at ~16 Ma. The localization of the Abukuma adakite, which excludes other areas of northeastern Japan, as well as Sikhote-Alin and Sakhalin, implies that the short-term temperature anomaly existed as a blob, which may have resulted from the penetration of the mantle plume through a neck in the subducting Pacific plate. The rising hot blob of the mantle plume from the slab neck was entrained to the corner flow of the mantle wedge and arrived at the slab surface at ~17 Ma. The pulse-like and localized Abukuma adakite was thus the consequence of short-term and localized plume-slab interaction in the Abukuma region. © 2014 Elsevier B.V.

Lee S.-Y.,Chonnam National University | Klassen R.D.,University of Western Ontario | Furlan A.,University of Padua | Vinelli A.,University of Padua
International Journal of Production Economics | Year: 2014

The bullwhip effect has long been recognized as a critical factor that amplifies demand variability as customer orders pass upstream through successive tiers of a supply chain. Like customer demand, environmental requirements also change significantly at times, and are passed along the supply chain to varying degrees, suggestive of what we term, the "green bullwhip effect". Based on field cases exploring changes in three supply chains across three adjacent tiers, we find evidence that such a phenomenon exists. First, ratcheting demands for better environmental performance are passed upstream through successive tiers with significant variation. Second, a green bullwhip effect is created as time to comply with specifications is compressed. Four different managerial responses, namely replace, accommodate, negotiate and collaborate, were observed to amplify or attenuate a green bullwhip effect based on the nature of firm relationships and balance of environmental capabilities at each tier. Of particular interest, the green bullwhip effect can force positive change, triggering the development of new environmental capabilities at multiple tiers in a supply chain. © 2014 The Authors.

Kang H.K.,Chonnam National University | Kimura A.,Hokkaido University | Kim D.,Chonnam National University
Journal of Agricultural and Food Chemistry | Year: 2011

The variations in glucosidic linkage specificity observed in products of different glucansucrases appear to be based on relatively small differences in amino acid sequences in their sugar-binding acceptor subsites. Various amino acid mutations near active sites of DSRBCB4 dextransucrase from Leuconostoc mesenteroides B-1299CB4 were constructed. A triple amino acid mutation (S642N/E643N/V644S) immediately next to the catalytic D641 (putative transition state stabilizing residue) converted DSRBCB4 enzyme from the synthesis of mainly α-(1→6) dextran to the synthesis of α-(1→6) glucan containing branches of α-(1→3) and α-(1→4) glucosidic linkages. The subsequent introduction of mutation V532P/V535I, located next to the catalytic D530 (nucleophile), resulted in the synthesis of an α-glucan containing increased branched α-(1→4) glucosidic linkages (approximately 11%). The results indicate that mutagenesis can guide glucansucrase toward the synthesis of various oligosaccharides or novel polysaccharides with completely altered linkages without compromising high transglycosylation activity and efficiency. © 2011 American Chemical Society.

El Saliby I.,University of Technology, Sydney | Erdei L.,University of Southern Queensland | Kim J.-H.,Chonnam National University | Shon H.K.,University of Technology, Sydney
Water Research | Year: 2013

In this study, Degussa P25 TiO2 was partially dissolved in a mixture of hydrogen peroxide and sodium hydroxide at high pH. The fabrication of nanofibres proceeded by the hydrothermal treatment of the solution at 80°C. This was followed by acid wash in HCl at pH 2 for 60min, which resulted in the formation of hydrogen-titanate nanofibres. The nanofibres were annealed at 550°C for 6h to produce crystalline anatase nanofibres. The nanofibres were characterised for physico-chemical modifications and tested for the adsorption and photocatalytic degradation of methylene blue as a model water pollutant. An average specific surface area of 31.54m2/g, average pore volume of 0.10cm3/g and average pore size of 50Å were recorded. The nanofibres were effective adsorbents of the model pollutant and adsorbents and good photocatalysts under simulated solar light illumination. No reduction in photocatalytic activity was observed over three complete treatment cycles, and the effective separation of nanofibres was achieved by gravity settling resulting in low residual solution turbidity. © 2013 Elsevier Ltd.

Lee B.K.,Chonnam National University | Jeung K.W.,Chonnam National University | Lee H.Y.,KS Hospital | Jung Y.H.,Chonnam National University | Lee D.H.,Chonnam National University
Resuscitation | Year: 2013

Aim of the study: We determined whether combining the grey-to-white matter ratio (GWR) on brain computed tomography (CT) and serum neuron specific enolase (NSE) improves the prognostic performance when compared to either alone in cardiac arrest patients treated with therapeutic hypothermia (TH). Methods: We performed a retrospective study of a cohort of cardiac arrest patients treated with TH. The Hounsfield unit was measured in the caudate nucleus (CN), putamen (P), posterior limb of internal capsule (PIC) and corpus callosum (CC); GWR was calculated as CN/PIC and P/CC. The NSE value was obtained at 0, 24, and 48. h after restoration of spontaneous circulation (ROSC). We analysed the prognostic performance of GWR and NSE, singly and in combination, in predicting poor neurologic outcome (cerebral performance category 3-5). Results: Of the 224 included patients, 82 showed good neurologic outcome at hospital discharge, while 142 showed poor neurologic outcome. The P/CC (area under receiver operating characteristics (AUROC) 0.864, sensitivity/specificity 52.9%/100%) showed better prognostic performance than did the CN/PIC (AUROC 0.721, sensitivity/specificity 19.8%/100%). The NSE value at 48. h after ROSC (AUROC 0.895, sensitivity/specificity 60.2%/100%) showed the highest prognostic value among the three NSE time points. Analysis of 119 patients undergoing both brain CT and NSE at 48. h indicated that combining P/CC and NSE improved the sensitivity (78.6%) compared to either alone (48.6%, 62.9%). Conclusion: Combining brain CT and serum NSE improves the prognostic performance when compared to either alone in predicting poor neurologic outcome in cardiac arrest patients treated with TH. © 2013 Elsevier Ireland Ltd.

Kang K.E.,Chonnam National University | Park D.-H.,Chonnam National University | Jeong G.-T.,Pukyong National University
Bioresource Technology | Year: 2013

This study focused on the effects of five inorganic salts, NaCl, KCl, CaCl2, ZnCl2, and FeCl3, on the pretreatment of Miscanthus straw for sugar recovery and enzymatic digestibility. In the results, all of the salts reduced the hemicellulose content in the straw. Most notably, FeCl3 effected almost 100% xylan removal. Overall, the trivalent salts, which include FeCl3, had an especially significant influence on enzymatic digestibility of Miscanthus straw compared with the di- and mono-valent inorganic salts, which had relatively only minor effects. The salt impacts were in the following order: FeCl3>ZnCl2>CaCl2>KCl>NaCl. Under the pretreatment condition of 0.5% FeCl3 at 200°C for 15min, 100% xylan removal and 71.6% enzymatic digestibility were obtained. Nevertheless, ZnCl2 get the better effect on total glucose content than that of FeCl3. © 2013 Elsevier Ltd.

Rai A.K.,Chonnam National University | Gim J.,Chonnam National University | Anh L.T.,Chonnam National University | Kim J.,Chonnam National University
Electrochimica Acta | Year: 2013

A simple urea-assisted, auto-combustion synthesis was used to fabricate pure Co3O4 nanoparticles and their nanocomposite with 10 wt% reduced graphene nanosheets. Samples were annealed at 500 C for 5 h under nitrogen atmosphere and their structures and morphologies were characterized by X-ray diffraction, field-emission scanning electron microscopy, field-emission transmission electron microscopy, Raman spectroscopy and BET surface area analysis. The process led to a nanocomposite containing small (25-50 nm) Co 3O4 nanoparticles deposited on the graphene nanosheets. CHN analysis determined the carbon content in pure Co3O4 nanoparticles and Co3O4/CoO/graphene nanocomposite and found to be very low such as 0.091% and 2.41% respectively. In addition, to know the precise amount of CoO in the designed nanocomposite sample, phase fraction Le Bail's technique was used and found to be 20 ± 0.5%. Using the Co 3O4/CoO/graphene nanocomposite as an anode in lithium ion battery led to a higher lithium storage capacity than using pure Co 3O4 nanoparticles electrode. The Co3O 4/CoO/graphene nanocomposite electrode delivered an initial charge capacity of 890.44 mAh g-1 and Exhibit 90% of good capacity retention (801.31 mAh g-1) after 30 cycles. While pure Co3O 4 nanoparticles electrode (877.98 mAh g-1) fades quickly, retains only 60% (523.94 mAh g-1) after 30 cycles. The improved electrochemical performance of nanocomposite was attributed to higher electron and Li+ ion conductivity and the larger surface area and mechanical flexibility afforded by the graphene nanosheets. At high current densities, both electrodes showed comparable reversible capacities, demonstrating the suitability of the present synthetic technique. © 2013 Elsevier Ltd.

Byun H.-S.,Chonnam National University
Journal of Industrial and Engineering Chemistry | Year: 2013

In this work, cloud-point and bubble-point phase behavior data are reported for the poly(dimethylsiloxane) [PDMSA] in supercritical carbon dioxide, propane, propylene, butane, 1-butene and dimethyl ether (DME). The static-type method, using a variable-volume view cell, was employed to obtain the experimental data at the temperature range for (315.2-454.9)K and pressure up to 55.52MPa. PDMS (Mw=38,900)+C4 cloud-point curves are ∼10MPa lower than the PDMS+C3 curves at constant temperature of 423K. Cloud-point curves for the PDMS+solvents system show the lower critical solution temperature (LCST) region. © 2012 The Korean Society of Industrial and Engineering Chemistry.

Lee H.-J.,Chonnam National University | Seo Y.-J.,Chonnam National University | Lee J.-W.,Chonnam National University
Bioresource Technology | Year: 2013

The properties of pretreated biomass and hydrolysate obtained by oxalic acid pretreatment using oxalic acid recovered through electrodialysis (ED) were investigated. Most of the oxalic acid was recovered and some of the fermentation inhibitors were removed by ED. For the original hydrolysate, the ethanol production was very low and fermentable sugars were not completely consumed by Pichia stipitis during fermentation. Ethanol yield was less than 0.12 g/g in all stage. For the ED-treated hydrolysate, ethanol production was increased by up to two times in all stages compared to the original hydrolysate. The highest ethanol production was 19.38 g/l after 72 h which correspond to the ethanol yield of 0.33 g/g. Enzymatic conversion of the cellulose to glucose for all the pretreated biomass was in the range of 76.03 and 77.63%. The hydrolysis rate on each pretreated biomass was not significantly changed when oxalic acid recovered by ED was used for pretreatment. © 2013 Elsevier Ltd.

Lim W.-S.,Chonnam National University | Lee J.-W.,Chonnam National University
Bioresource Technology | Year: 2013

The aim of this study was to investigate the effects of different acid catalysts and pretreatment factors on the hydrolysis of biomass compounds over a range of thermochemical pretreatments; maleic, oxalic, and sulfuric acids were each used under different pretreatment conditions. The most influential factor for fermentable sugar production in the dicarboxylic acid-pretreated mixed hardwood was pH. Reaction time was the next significant factor followed by reaction temperature. However, fermentable sugar production was more dependent on reaction temperature than time during sulfuric acid pretreatment, whereas the effect of acid concentration was considerably lower. Maleic acid pretreatment was very effective for attaining high glucose yields after enzymatic hydrolysis. The highest enzymatic hydrolysis yield was found following maleic acid pretreatment, which reached 95.56%. The trend in enzymatic hydrolysis yields that were detected concomitantly with pretreatment condition or type of acid catalyst was closely related to xylose production in the hydrolysate. © 2012.

Park S.-H.,Chonnam National University | Jung H.-R.,Chonnam National University | Lee W.-J.,Chonnam National University
Electrochimica Acta | Year: 2013

Hollow activated carbon nanofibers (H-ACNF) were prepared by concentric electrospinning of poly(methyl methacrylate) (PMMA) as a pyrolytic core precursor and polyacrylonitrile (PAN) as a carbon shell precursor, followed by stabilization, carbonization, and activation. The H-ACNF with 190 and 270 nm for core and shell diameter showed excellent mesoporous structure, and 1-D conducting pathway in employing as catalysts of counter electrodes (CEs) for dye-sensitized solar cells (DSCs). The mesoporous structure of H-ACNF represented surface area of 1037.5 m2 g-1 with average mesopore diameter of 17.4 nm. The overall conversion efficiency of H-ACNF is comparable to that of Pt CE because its characteristics promotes the electron and ion transfer, decreases the resistance of charge transfer, and increases the contact area between liquid electrolyte and H-ACNF. © 2013 Elsevier Ltd. All rights reserved.

Lee H.-J.,Chonnam National University | Ahn S.J.,Chonnam National University | Seo Y.-J.,Chonnam National University | Lee J.-W.,Chonnam National University
Bioresource Technology | Year: 2013

The present study investigated the feasibility of the recovery and reuse oxalic acid in a multistage process for the pretreatment of a lignocellulosic biomass. Electrodialysis (ED), an electrochemical process using ion exchange membranes, was used to recover and reuse oxalic acid in the multistage process. The ED optimal condition for recover oxalic acid was potential of 10. V and pH 2.2 in synthetic solutions. The recovery efficiency of oxalic acid from hydrolysates reached 100% at potential of 10. V. The power consumption to treat 1. mol of oxalic acid was estimated to be 41.0. wh. At the same time, ethanol production increased up to 19. g/L in the ED-treated hydrolysate, corresponding to ethanol productivity of 0.27. g/L/h. It was clearly shown that bioethanol fermentation efficiency increased using the ED process, due to a small loss of fermentable sugar and a significantly high removal of inhibitory chemicals. © 2012 Elsevier Ltd.

Lee H.-J.,Chonnam National University | Cho E.J.,Chonnam National University | Kim Y.-G.,Chonnam National University | Choi I.S.,Chonnam National University | Bae H.-J.,Chonnam National University
Bioresource Technology | Year: 2012

Pervaporation is one of the most promising separation processes for the purification of ethanol. In this study, a composite hollow-fiber membrane with a thin polydimethylsiloxane (PDMS) active layer on a polyetherimide (PEI) macroporous support was used for pervaporative separation of ethanol produced by Saccharomyces cerevisiae from glucose fermentation broth.The pervaporation performance for ethanol/water binary mixtures was strongly dependent on the feed concentration and operating temperature for ethanol concentrations of 1-10%. The composite hollow-fiber membrane was stable over the long-term (about 160days) with an ethanol permeation flux of 60-62g/m 2h and a separation factor of 7-9. In comparison with published results for PDMS composite membranes, the PDMS/PEI hollow-fiber composite membrane had relatively good pervaporation performance with a total flux of 231-252g/m 2h. © 2012 Elsevier Ltd.

Kang K.E.,Chonnam National University | Jeong G.-T.,Pukyong National University | Park D.-H.,Chonnam National University
Bioprocess and Biosystems Engineering | Year: 2012

Pretreatment method for rapeseed straw by sodium hydroxide was investigated for production of bioethanol and biobutanol. Various pretreatment parameters, including temperature, time, and sodium hydroxide concentration were optimized using a statistical method which is a central composite design of response surface methodology. In the case of sodium hydroxide pretreatment, optimal pretreatment conditions were found to be 7.9% sodium hydroxide concentration, 5.5 h of reaction time, and 68.4 °C of reaction temperature. The maximum glucose yield which can be recovered by enzymatic hydrolysis at the optimum conditions was 95.7% and the experimental result was 94.0 ± 4.8%. This experimental result was in agreement with the model prediction. An increase of surface area and pore size in pretreated rapeseed straw by sodium hydroxide pretreatment was observed by scanning electron microscope. © Springer-Verlag 2011.

Kim Y.J.,Chonnam National University
The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi | Year: 2012

We report herein a case of intestinal amyloidosis with grave prognosis that caused intractable diarrhea and intestinal pseudo-obstruction, alternately in spite of intensive conservative treatment. A 44-year-old woman was admitted for fever, diarrhea, and crampy abdominal pain which had been continuned during 6 months. Abdomen CT scan showed edematous wall thickening of the small bowel and right colon, and colonoscopic biopsy revealed amyloid deposition in the mucosa. Monoclonal light chains in serum and/or urine were not detected and highly elevated serum amyloid A was shown. In spite of intensive treatment including oral prednisolone and colchicine, diarrhea and intestinal pseudo-obstruction developed alternately, general status rapidly got worsened and died after two months.

We present an analytical calculation of temporal evolution of populations for optically pumped atoms under the influence of weak, circularly polarized light. The differential equations for the populations of magnetic sublevels in the excited state, derived from rate equations, are expressed in the form of inhomogeneous second-order differential equations with constant coefficients. We present a general method of analytically solving these differential equations, and obtain explicit analytical forms of the populations of the ground state at the lowest order in the saturation parameter. The obtained populations can be used to calculate lineshapes in various laser spectroscopies, considering transit time relaxation. © 2016 MDPI.

Lee J.-W.,Chonnam National University | Kim Y.-H.,Chonnam National University | Lee S.-M.,Korea forest Research Institute | Lee H.-W.,Chonnam National University
Bioresource Technology | Year: 2012

The optimal conditions for the torrefaction of mixed softwood were investigated by response surface methodology. This showed that the chemical composition of torrefied biomass was influenced by the severity factor of torrefaction. The lignin content in the torrefied biomass increased with the SF, while holocellulose content decreased. Similarly, the carbon content energy value of torrefied biomass ranged from 19.31 to 22.12. MJ/kg increased from 50.79 to 57.36%, while the hydrogen and oxygen contents decreased. The energy value of torrefied biomass ranged from 19.31 to 22.12. MJ/kg. This implied that the energy contained in the torrefied biomass increased by 4-19%, when compared with the untreated biomass. The energy value and weight loss in biomass slowly increased as the SF increased up until 6.12; and then dramatically increased as the SF increased further from 6.12 to 7.0. However, the energy yield started decreasing at SF value higher than 6.12; and the highest energy yield was obtained at low SF. © 2012.

Kang N.Y.,Chonnam National University | Lee H.W.,Chonnam National University | Kim J.,Chonnam National University
Plant and Cell Physiology | Year: 2013

The developmental process of lateral root formation consists of priming, initiation, primordium development and the emergence of lateral roots from the primary root. Molecular genetic studies with Arabidopsis have revealed several key transcriptional regulators involved in lateral root development. However, their functional interaction has not been fully characterized yet. Here we utilized a genetic approach to understand some of these interactions, revealing that PUCHI functioning in morphogenesis of early lateral root primordium is regulated downstream of ARF7/ARF19 and acts with LBD16(ASL18)/LBD18(ASL20) to regulate lateral root development. We showed that auxin-responsive expression of PUCHI was significantly reduced in arf7 or arf19 single mutants and completely abolished in arf7 arf19 double mutants. Consistent with this, β-glucuronidase (GUS) expression under the PUCHI promoter in arf7 arf19 was greatly reduced in the lateral root primordium compared with that in the wild type and did not respond to exogenous auxin. Results of GUS expression analyses under the PUCHI, LBD16 or LBD18 promoter in lbd16, lbd18 single and double mutants or puchi demonstrated that PUCHI and LBD16 or LBD18 do not regulate each other's expression. Lateral root phenotypes of double and triple mutants of lbd16, lbd18 and puchi showed that the puchi mutation in lbd16 and lbd18 mutants synergistically decreased the number of emerged lateral roots. These analyses also showed that puchi affected lateral root primordium development of lbd16 or lbd18 additively but differentially. Taken together, these results suggest that PUCHI co-acts with LBD16 and LBD18 to control lateral root primordium development and lateral root emergence. © 2013 The Author.

Kim S.S.,Chonnam National University | Park Y.-K.,Kyung Hee University
Cancer and Metastasis Reviews | Year: 2014

Osteosarcoma is the most common malignant bone tumor in children and characterized by aggressive biologic behavior of metastatic propensity to the lung. Change of treatment paradigm brings survival benefit; however, 5-year survival rate is still low in patients having metastastatic foci at diagnosis for a few decades. Metastasis-associated protein (MTA) family is a group of ubiquitously expressed coregulators, which influences on tumor invasiveness or metastasis. MTA1 has been investigated in various cancers including osteosarcoma, and its overexpression is associated with high-risk features of cancers. In this review, we described various molecular studies of osteosarcoma, especially associated with MTA1. © 2014, Springer Science+Business Media New York.

Byeon Y.,Chonnam National University | Lee H.Y.,Chonnam National University | Choi D.-W.,Chonnam National University | Back K.,Chonnam National University
Journal of Experimental Botany | Year: 2015

Melatonin biosynthesis involves the N-acetylation of arylalkylamines such as serotonin, which is catalysed by serotonin N-acetyltransferase (SNAT), the penultimate enzyme of melatonin biosynthesis in both animals and plants. Here, we report the functional characterization of a putative N-acetyltransferase gene in the chloroplast genome of the alga laver (Pyropia yezoensis, formerly known as Porphyra yezoensis) with homology to the rice SNAT gene. To confirm that the putative Pyropia yezoensis SNAT (PySNAT) gene encodes an SNAT, we cloned the full-length chloroplastidic PySNAT gene by PCR and purified the recombinant PySNAT protein from Escherichia coli. PySNAT was 174 aa and had 50% amino acid identity with cyanobacteria SNAT. Purified recombinant PySNAT showed a peak activity at 55 °C with a Km of 467 μM and Vmax of 28 nmol min-1 mg-1 of protein. Unlike other plant SNATs, PySNAT localized to the cytoplasm due to a lack of N-terminal chloroplast transit peptides. Melatonin was present at 0.16 ng g-1 of fresh mass but increased during heat stress. Phylogenetic analysis of the sequence suggested that PySNAT has evolved from the cyanobacteria SNAT gene via endosymbiotic gene transfer. Additionally, the chloroplast transit peptides of plant SNATs were acquired 1500 million years ago, concurrent with the appearance of green algae. © The Author 2014.

Yoo H.-D.,Chonnam National University | Cho H.-Y.,Korea Food and Drug Administration | Lee Y.-B.,Chonnam National University
British Journal of Clinical Pharmacology | Year: 2010

Aims To investigate the influence of genetic polymorphisms in the CYP3A5, CYP2C19 and ABCB1 genes on the population pharmacokinetics of cilostazol in healthy subjects. Methods Subjects who participated in four separate cilostazol bioequivalence studies with the same protocols were included in this retrospective analysis. One hundred and four healthy Korean volunteers were orally administered a single 50- or 100-mg dose of cilostazol. We estimated the population pharmacokinetics of cilostazol using a nonlinear mixed effects modelling (nonmem) method and explored the possible influence of genetic polymorphisms in CYP3A (CYP3A5*3), CYP2C19 (CYP2C19*2 and CYP2C19*3) and ABCB1 (C1236T, G2677T/A and C3435T) on the population pharmacokinetics of cilostazol. Results A two-compartment model with a first-order absorption and lag time described the cilostazol serum concentrations well. The apparent oral clearance (CL/F) was estimated to be 12.8 l h-1. The volumes of the central and the peripheral compartment were characterized as 20.5 l and 73.1 l, respectively. Intercompartmental clearance was estimated at 5.6 l h-1. Absorption rate constant was estimated at 0.24 h-1 and lag time was predicted at 0.57 h. The genetic polymorphisms of CYP3A5 had a significant (P < 0.001) influence on the CL/F of cilostazol. When CYP2C19 was evaluated, a significant difference (P < 0.01) was observed among the three genotypes (extensive metabolizers, intermediate metabolizers and poor metabolizers) for the CL/F. In addition, a combination of CYP3A5 and CYP2C19 genotypes was found to be associated with a significant difference (P < 0.005) in the CL/F. When including these genotypes, the interindividual variability of the CL/F was reduced from 34.1% in the base model to 27.3% in the final model. However, no significant differences between the ABCB1 genotypes and cilostazol pharmacokinetic parameters were observed. Conclusions The results of the present study indicate that CYP3A5 and CYP2C19 polymorphisms explain the substantial interindividual variability that occurs in the metabolism of cilostazol. © 2010 The Authors. Journal compilation © 2010 The British Pharmacological Society.

Choi S.-I.,Chonnam National University | Park J.,Chonnam National University
Journal of Optical Communications and Networking | Year: 2010

The Ethernet passive optical network (EPON) is one of the most promising broadband access networks. We propose a new dynamic scheduling algorithm, referred to as cyclic-polling-based dynamic bandwidth allocation with service level agreements (CPBA-SLA), for service differentiation that meets the service level agreements between the OLT and ONUs. The proposed dynamic bandwidth allocation (DBA) scheme provides a constant and predictable average packet delay and an improved delay jitter of the expedited forwarding traffic without the influence of load variations. A performance evaluation shows the effectiveness of the proposed DBA scheme. © 2009 OSA.

Jung S.,Chonnam National University
Bioresource technology | Year: 2010

Transgenic tobacco plants expressing the hyperthermostable beta-glucosidase BglB of Thermotoga maritima were generated with the goal of cost-effective production of the enzyme for the application in bioconversion of lignocellulosic biomass. The enzyme was targeted to the cytosol and chloroplasts, where it accumulated to level of 4.5% and 5.8% of total soluble protein, respectively. The optimal temperature and pH of the plant-expressed BglB was 80 degrees C and 4.5, respectively. BglB activity was preserved in leaves after lyophilization, but decreased by over 70% with drying at room temperature. When BglB was synergistically supplied in a 1% (w/v) rice straw with Cel5A for efficient cellulase conversion, a 37% increase in glucose was observed. This report demonstrates the potential of utilizing transgenic tobacco for mass production of BglB. Copyright 2010 Elsevier Ltd. All rights reserved.

Chang C.L.,Chang Gung University | Cai J.J.,Stanford University | Cai J.J.,Texas A&M University | Lo C.,University College London | And 3 more authors.
Genome Research | Year: 2011

Diversities in human physiology have been partially shaped by adaptation to natural environments and changing cultures. Recent genomic analyses have revealed single nucleotide polymorphisms (SNPs) that are associated with adaptations in immune responses, obvious changes in human body forms, or adaptations to extreme climates in select human populations. Here, we report that the human GIP locus was differentially selected among human populations based on the analysis of a nonsynonymous SNP (rs2291725). Comparative and functional analyses showed that the human GIP gene encodes a cryptic glucose-dependent insulinotropic polypeptide (GIP) isoform (GIP55S or GIP55G) that encompasses the SNP and is resistant to serum degradation relative to the known mature GIP peptide. Importantly, we found that GIP55G, which is encoded by the derived allele, exhibits a higher bioactivity compared with GIP55S, which is derived from the ancestral allele. Haplotype structure analysis suggests that the derived allele at rs2291725 arose to dominance in East Asians ∼8100 yr ago due to positive selection. The combined results suggested that rs2291725 represents a functional mutation and may contribute to the population genetics observation. Given that GIP signaling plays a critical role in homeostasis regulation at both the enteroinsular and enteroadipocyte axes, our study highlights the importance of understanding adaptations in energy-balance regulation in the face of the emerging diabetes and obesity epidemics. © 2011 by Cold Spring Harbor Laboratory Press.

Jung H.-Y.,Kangwon National University | Jung H.-Y.,Chonnam National University | Kim J.W.,Kangwon National University
International Journal of Hydrogen Energy | Year: 2012

The glass transition temperature (T g) of the Nafion 117 membrane was traced by DSC step by step during the preparation of the membrane electrode assembly (MEA). Wide-angle x-ray diffraction and frequency response analysis were used for the determination of the crystallinity and proton conductivity of the membrane. As-received Nafion 117 membrane showed two glass transition temperatures in the DSC thermogram. The first T g, caused by the mobility of the main chain in the polymer matrix, was 125°C; the second T g, derived from the side chain due to the strong interaction between the sulfonic acid functional groups, was 195°C. During the pretreatment of the membrane, the T g of the Nafion 117 membrane drastically decreased because of the plasticizer effect of water. In the hot-pressing process, the T g of the Nafion 117 membrane gradually increased due to the loss of water. When the Nafion 117 was completely dried, the T g of the membrane finally reached 132°C. Thermal heat treatment was then applied to the MEA to obtain high interfacial stability; however, the membrane developed a crystalline morphology that led to reduced water uptake and proton conductivity. Therefore, the thermal heat treatment of the MEA should be carefully controlled in the region of the glass transition temperature (120-140°C) of the Nafion 117 membrane to ensure the high performance of the MEA. © 2012 Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Kim Y.,Chonnam National University | Hong O.,University of California at San Francisco
American Journal of Health Behavior | Year: 2013

Objectives: To understand the predictors of controlled drinking in Korean male workers with a structural equation modeling based on Ajzen's theory of planned behavior. Methods: A cross-sectional survey design was used with a total of 315 male workers from 20 workplaces. Results: The modified model accounted for 58% of intentions and 20% of controlled drinking behavior. The component most increasing intentions was perceived behavior control (PBC), and the components increasing controlled drinking behavior were intentions and PBC in the modified model. Conclusions: Intervention programs should be designed to increase intentions and PBC to improve controlled drinking behavior in male workers.

Park S.S.,Chonnam National University | Hansen A.D.A.,Magee Scientific | Cho S.Y.,Chonnam National University
Atmospheric Environment | Year: 2010

Measurements of real-time continuous PM 2.5 black carbon (BC) concentrations were made using a single-wavelength Aethalometer (@880 nm) in three different environments, i.e., an indoor office, a residential indoor living room and an urban site, to evaluate the difference in temporal behaviors of BC particles and investigate the optical shadowing effect in the Aethalometer BC data. An empirical method was used for correcting the optical saturation effect on the original BC data obtained from the measurements at the three sites. Also, the elemental carbon (EC) concentrations from 24-h filter-based measurements of PM 2.5 particles were determined using a thermal optical transmittance (TOT) method at the same urban site for comparison with the Aethalometer BC results. Transient events of BC were often observed for period of a few hours at all sites, reaching a maximum level of 27.3 μg m -3 at the urban site. The diurnal cycles of the BC concentrations observed at the two indoor environments were found to be considerably affected by the air exchange rate, occupants' behavior patterns and nearby traffic emissions. The time-series plots of the Aethalometer data showed obvious discontinuities at the filter spot change, and a rise in the apparent BC concentrations after filter tape advances. Also, the relationship between the attenuation and BC concentration was found to be non-linear at all sites. The empirical approach presented here demonstrated a definite improvement in the continuity of the BC data across the time gaps of each tape advance. The compensated BC concentration was 1.10-1.23 times greater than the raw BC data, depending on the observation sites, with the highest difference observed between the raw and compensated BC data at an indoor office near a small traffic road. The 24-h integrated EC concentration was approximately 12% higher than the original 24-h average BC concentration and 6% lower than the loading compensated BC concentration, showing that the loading compensation process accounted for the saturation effect of the filter tape. © 2010 Elsevier Ltd. All rights reserved.

Lee Y.K.,Kongju National University | Kim Y.H.,Chonnam National University | Heo J.,Pohang University of Science and Technology | Im W.B.,Chonnam National University | Chung W.J.,Kongju National University
Optics Letters | Year: 2014

Phosphor-in-glass (PiG) color converters for LED applications were fabricated with a mixture of phosphors, Y3Al5O 12:Ce3+ (yellow) and CaAlSiN3:Eu2+ (red). The low sintering temperature (550°C) of SiO2-Na 2O-RO (R = Ba, Zn) glass powder enabled the inclusion of CaAlSiN 3:Eu2+ (red) phosphor which cannot be embedded with conventional glass powders for PiGs. By simply varying the mixing ratio of glass to phosphors as well as the ratio of yellow to red phosphors, the facile control of the CIE chromaticity coordinates and correlated color temperature of the LED following the Planckian locus has been achieved. Phosphors were well distributed within the glass matrix without noticeable reactions, preserving the enhanced thermal quenching property of the PiG compared to those with silicone resins, for LEDs. © 2014 Optical Society of America.

Ham D.-H.,Chonnam National University
Cognition, Technology and Work | Year: 2014

A great deal of study has been devoted to the problem of how to identify and categorize usability problems; however, there is still a lack of studies dealing with the problem of how to diagnose the causes of usability problems and how to feed them back into design process. The value of classifying usability problems can be enhanced when they are interpreted in connection with design process and activities. Thus, it is necessary to develop a systematic way of diagnosing usability problems in terms of design aspects and applying diagnosis results to improve design process and activities. With this issue in mind, this paper proposes a conceptual framework that supports a systematic classification and diagnosis of usability problems. This paper firstly reviews seven approaches to classifying usability problems. Then, we point out the needs of adopting a model-based approach to classifying and diagnosing usability problems and of developing a comprehensive framework guiding the use of model-based approaches. We then propose a conceptual framework that specifies how a model-based classification and diagnosis of usability problems should be conducted and suggests the combined use of three different types of models, each of which addresses context of use, design knowledge and design activities. Last, we explain how a sound classification scheme of usability problems can be systematically developed, and how the classification of usability problems can be connected to design process and activities on the basis of the framework. © 2013 Springer-Verlag London.

Aravindan V.,Nanyang Technological University | Gnanaraj J.,Yardney Technical Products, Inc. | Lee Y.-S.,Chonnam National University | Madhavi S.,Nanyang Technological University
Chemical Reviews | Year: 2014

Apart from the mentioned applications, wind power generation, uninterruptible power sources, voltage sag compensation, photovoltaic power generation, CT and MRI scanners, and energy recovery systems in industrial machineries are worth mentioning. Carbonaceous materials are favored as EDLC components due to their high specific surface area, relatively low cost, chemical stability in solutions irrespective of the pH value, ease of synthesis protocols with tailored pore size distribution and its amphoteric nature that allows rich electrochemical properties from donor to acceptor state, and a wide range of operating temperatures. The combination reactions enable one to achieve higher energy density and specific capacitance than the EDLC counterpart. Conducting polymers and transition metal oxides are the perfect examples for pseudocapacitive materials.

Oh J.,Chonnam National University | Lee C.,Seoul National University of Science and Technology
ISPRS Journal of Photogrammetry and Remote Sensing | Year: 2015

As the need for efficient methods to accurately update and refine geospatial satellite image databases is increasing, we have proposed the use of 3-dimensional digital maps for the fully-automated RPCs bias compensation of high resolution satellite imagery. The basic idea is that the map features are scaled and aligned to the image features, except for the local shift, through the RPCs-based image projection, and then the shifts are automatically determined over the entire image space by template-based edge matching of the heterogeneous data set. This enables modeling of RPCs bias compensation parameters for accurate georeferencing. The map features are selected based on four suggested rules. Experiments were carried out for three Kompsat-2 images and stereo IKONOS images with 1:5000 scale Korean national topographic maps. Image matching performance is discussed with justification of the parameter selection, and the georeferencing accuracy is analyzed. The experimental results showed the automated approach can achieve one-pixel level of georeferencing accuracy, enabling economical hybrid map creation as well as large scale map updates. © 2014 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS).

Lyu S.O.,Dongseo University | Oh C.-O.,Chonnam National University
Leisure Sciences | Year: 2014

Unlike prospective participants with desire for initial participation, current participants are likely to have different interest in habitual leisure engagement from participation itself. Accordingly, they may respond to the effects of leisure constraints differently in order to progress toward a higher level of leisure involvement. This study aims to construct a theoretical framework that demonstrates how diverse components of current participants’ constraints negotiation process are conceptually connected to each other. Study results suggest that different negotiation strategies help current participants adjust their willingness to participate in the activity more frequently. Results also denote that the three dimensions of leisure constraints are differently associated with cognitive negotiation strategies, and commitment plays an important role in promoting the use of negotiation strategies to mitigate current participants’ perception of leisure constraints. © 2014, © Taylor & Francis Group, LLC.

Moon C.-M.,Chonnam National University | Jeong G.-W.,Chonnam National University
Psychiatry and Clinical Neurosciences | Year: 2015

Aims Patients with generalized anxiety disorder (GAD) suffer the symptoms of psychological distress, including excessive and uncontrollable anxiety. Until now, the functional neuroanatomy for working memory (WM) in conjunction with the major anxiety symptoms in GAD patients has not yet been clearly identified. This study investigated the neural activation patterns associated with the effect of neutral and anxiety-inducing distractors during the delayed-response WM task in GAD patients. Methods Eighteen patients with GAD and 18 age-matched healthy controls participated in this study. The functional magnetic resonance images were obtained while the subjects performed a delayed-response WM task with neutral and anxiety-inducing distractors. Results During the neutral distractor, GAD patients compared to controls showed significantly lower activities in the fusiform gyrus, superior parietal gyrus, precuneus, superior occipital gyrus, lingual gyrus, cuneus, calcarine gyrus, parahippocampal gyrus and cerebellar cortex. During the anxiety-inducing distractor, GAD patients showed significantly higher activity in the hippocampus, whereas they showed lower activities in the dorsolateral prefrontal cortex, fusiform gyrus, superior parietal gyrus, precuneus, superior occipital gyrus and cerebellar cortex. The blood-oxygen-level dependent signal changes in the dorsolateral prefrontal cortex in GAD patients during the anxiety-inducing distractor were negatively correlated with Anxiety Sensitivity Index-Revised scores. Conclusions This study identified the specific brain areas associated with the interaction between emotional regulation and cognitive function associated with neutral and anxiety-inducing distractors during WM maintenance in GAD patients. These findings will be helpful for understanding the neural mechanism on the WM-related cognitive deficits and emotional dysfunction with typical anxiety symptoms in GAD. © 2015 The Authors. Psychiatry and Clinical Neurosciences.

Moon C.-M.,Chonnam National University | Kang H.-K.,Chonnam National University | Jeong G.-W.,Chonnam National University
Psychiatry and Clinical Neurosciences | Year: 2015

Aims A few neuroimaging studies have demonstrated the key brain areas associated with generalized anxiety disorder (GAD). However, the brain metabolic changes in the dorsolateral prefrontal cortex (DLPFC) of patients with GAD are unclear. This study utilized 3-Tesla proton magnetic resonance spectroscopy (1H-MRS) to assess the DLPFC metabolic change and its correlation with symptom severity in patients with GAD. Methods Patients with GAD diagnosed using the DSM-IV-TR and age-matched healthy controls participated in this study. Brain metabolite concentrations were measured from a localized voxel on the DLPFC using 3-Tesla 1H-MRS. Also, the volumetric composition of the gray matter and white matter volumes was assessed using voxel-based morphometry. Results The choline/creatine and choline/N-acetylaspartate ratios were significantly lower in patients than in controls. However, there were no significant differences in other metabolite ratios between the two groups. Choline concentrations were negatively correlated with anxiety levels as measured by the Hamilton Anxiety Rating Scale and the Generalized Anxiety Disorder Scale 7. There was no significant difference in the gray matter and white matter volumes in the MRS voxel between the two groups. Conclusions The present study demonstrates that GAD is associated with low a level of choline/N-acetylaspartate in the DLPFC, which is closely related with symptom severity and cognitive dysfunction. This finding will be useful for an understanding of the neural mechanism associated with GAD. © 2015 The Authors. Psychiatry and Clinical Neurosciences © 2015 Japanese Society of Psychiatry and Neurology.

Aravindan V.,Chonnam National University | Aravindan V.,Nanyang Technological University | Karthikeyan K.,Chonnam National University | Kang K.S.,Korea Advanced Institute of Science and Technology | And 3 more authors.
Journal of Materials Chemistry | Year: 2011

Superior lithium storage in Li2MnSiO4 cathodes was observed by altering carbon content during the formulation of electrodes. Initially, Li2MnSiO4 was prepared by a conventional solid-state reaction at 900°C under Ar flow with a fixed amount of adipic acid, which acts as a gelating agent during synthesis. The phase formation was confirmed through powder X-ray diffraction measurements. Scanning electron microscope pictures indicate the particulate morphology of synthesized Li 2MnSiO4 particles. Various compositions of electrodes were formulated using the conducting carbon (ketjen black) from 3 to 11 mg along with active material. All the fabricated electrodes were cycled in a Li/Li 2MnSiO4 cell configuration to evaluate its lithium storage performance at 0.05 C rate. Among the electrodes, 42% carbon in the composite electrode exhibited a very stable discharge behaviour ∼140 mA h g -1 for 40 cycles at room temperature. Such storage performance was ascribed to the improved electronic conductivity of Li2MnSiO 4 electrodes by incorporating carbon. This improvement was supported by electrochemical impedance spectroscopy measurements. Rate performance studies were also conducted and presented in the manuscript. © 2011 The Royal Society of Chemistry.

Park H.-W.,Chonnam National University | Lee K.-B.,Chonnam National University | Chung J.-Y.,Chonnam National University | Kim M.-S.,Chonnam National University
Bone and Joint Journal | Year: 2013

Severe hallux valgus deformity is conventionally treated with proximal metatarsal osteotomy. Distal metatarsal osteotomy with an associated soft-tissue procedure can also be used in moderate to severe deformity. We compared the clinical and radiological outcomes of proximal and distal chevron osteotomy in severe hallux valgus deformity with a soft-tissue release in both. A total of 110 consecutive female patients (110 feet) were included in a prospective randomised controlled study. A total of 56 patients underwent a proximal procedure and 54 a distal operation. The mean follow-up was 39 months (24 to 54) in the proximal group and 38 months (24 to 52) in the distal group. At follow-up the hallux valgus angle, intermetatarsal angle, distal metatarsal articular angle, tibial sesamoid position, American Orthopaedic Foot and Ankle Society (AOFAS) hallux metatarsophalangeal-interphalangeal score, patient satisfaction level, and complications were similar in each group. Both methods showed significant post-operative improvement and high levels of patient satisfaction. Our results suggest that the distal chevron osteotomy with an associated distal soft-tissue procedure provides a satisfactory method for correcting severe hallux valgus deformity. © 2013 The British Editorial Society of Bone and Joint Surgery.

Song E.-K.,Chonnam National University | Seon J.-K.,Chonnam National University | Yim J.-H.,Chonnam National University | Netravali N.A.,Curexo Technology | Bargar W.L.,University of California at Los Angeles
Clinical Orthopaedics and Related Research | Year: 2013

Background: Several studies have shown mechanical alignment influences the outcome of TKA. Robotic systems have been developed to improve the precision and accuracy of achieving component position and mechanical alignment. Questions/purposes: We determined whether robotic-assisted implantation for TKA (1) improved clinical outcome; (2) improved mechanical axis alignment and implant inclination in the coronal and sagittal planes; (3) improved the balance (flexion and extension gaps); and (4) reduced complications, postoperative drainage, and operative time when compared to conventionally implanted TKA over an intermediate-term (minimum 3-year) followup period. Methods: We prospectively randomized 100 patients who underwent unilateral TKA into one of two groups: 50 using a robotic-assisted procedure and 50 using conventional manual techniques. Outcome variables considered were postoperative ROM, WOMAC scores, Hospital for Special Surgery (HSS) knee scores, mechanical axis alignment, flexion/extension gap balance, complications, postoperative drainage, and operative time. Minimum followup was 41 months (mean, 65 months; range, 41-81 months). Results: There were no differences in postoperative ROM, WOMAC scores, and HSS knee scores. The robotic-assisted group resulted in no mechanical axis outliers (> ± 3 from neutral) compared to 24% in the conventional group. There were fewer robotic-assisted knees where the flexion gap exceeded the extension gap by 2 mm. The robotic-assisted procedures took an average of 25 minutes longer than the conventional procedures but had less postoperative blood drainage. There were no differences in complications between groups. Conclusions: Robotic-assisted TKA appears to reduce the number of mechanical axis alignment outliers and improve the ability to achieve flexion-extension gap balance, without any differences in clinical scores or complications when compared to conventional manual techniques. Level of Evidence: Level I, therapeutic study. See Instructions for Authors for a complete description of levels of evidence. © 2012 The Association of Bone and Joint Surgeons®.

Xu Z.,Tianjin Medical University | Xu Z.,University of North Carolina at Chapel Hill | Kim S.,Chonnam National University | Huh J.,Seoul National University
Journal of Molecular and Cellular Cardiology | Year: 2014

This study investigated if zinc plays a role in postconditioning-induced cardioprotection in rat hearts. Isolated rat hearts were subjected to 30min regional ischemia followed by 2h of reperfusion. Postconditioning was elicited by 6cycles of 10s reperfusion and 10s ischemia. Cytosolic zinc concentrations were measured with inductively coupled plasma optical emission spectroscopy (ICPOES). Infarct size was assessed by triphenyltetrazolium chloride staining. Cytosolic zinc concentrations were decreased dramatically upon reperfusion in the control hearts. In contrast, postconditioning increased cytosolic zinc levels at reperfusion. The anti-infarct effect of postconditioning was inhibited by the selective zinc chelator N,N,N',N'-tetrakis-(2-pyridylmethyl) ethylenediamine (TPEN). Postconditioning significantly increased phosphorylation levels of the reperfusion injury salvage kinases (RISK) including Akt (Ser473), extracellular signal-regulated kinase1/2 (ERK1/2) (Thr202/Tyr204), and glycogen synthase kinase-3β (GSK-3β) (Ser9) at reperfusion, which were nullified by TPEN. Postconditioning decreased the activity of protein phosphatase 2A (PP2A) in a zinc-dependent manner. Knockdown of the zinc transporter Zip2 inhibited the protective effect of postconditioning on hypoxia/reoxygenation injury in H9c2 cells. These results suggest that zinc plays an important role in the cardioprotective effect of postconditioning presumably by enhancing the activation of the RISK pathway. Zip2 and inactivation of PP2A by zinc may, at least in part, account for the activation of the RISK pathway. © 2013 Elsevier Ltd.

The optimal dose of remifentanil to attenuate the cardiovascular responses to tracheal intubation in pre-eclamptic patients undergoing Caesarean delivery under general anaesthesia has not been established. We compared the effects of two low doses of remifentanil on the cardiovascular responses to tracheal intubation and neonatal outcomes. Forty-eight women with severe pre-eclampsia were randomly assigned to receive either remifentanil 0.5 μg kg1 (R0.5 group, n=24) or 1 μg kg1 (R1.0 group, n=24) over 30 s before induction of anaesthesia using thiopental 5 mg kg1 and succinylcholine 1.5 mg kg1. Systolic arterial pressure (SAP), heart rate (HR), and plasma catecholamine concentrations were measured. Neonatal effects were assessed using Apgar scores and umbilical cord blood gas analysis. SAP was decreased by induction of anaesthesia and increased by tracheal intubation in both groups. The peak SAP after intubation was greater in the R0.5 group than in the R1.0 group, whereas it did not exceed baseline values in either group. HR increased significantly above baseline in both groups with no significant differences between the groups. Three subjects in the R1.0 group received ephedrine due to hypotension (SAP < 90 mm Hg). Norepinephrine concentrations remained unaltered after intubation and increased significantly at delivery with no significant differences between the groups. Neonatal Apgar scores and umbilical arterial and venous pH and blood gas values were comparable between the groups. Both doses of remifentanil effectively attenuated haemodynamic responses to tracheal intubation with transient neonatal respiratory depression in pre-eclamptic patients undergoing Caesarean delivery under general anaesthesia. The 1.0 μg kg1 dose was associated with hypotension in three of 24 subjects.

Kang B.,Chonnam National University
Journal of Applied Fluid Mechanics | Year: 2015

In this paper, the effects of a step edge and a stationary droplet on the dynamic behavior of a droplet impacting upon a wall are experimentally studied. the main parameters were the distance from the step edge to the center of the impacting droplet and the center-to-center distance between the stationary and impacting droplets. photographic images showed the coalescence dynamics, shape evolution and contact line movement of the impacting droplet. the spread length is presented for the step edge and two coalescing droplets. the droplets exhibited much different dynamic behavior depending on the location of the step edge. the momentum of the impacting droplet was better transferred to the stationary droplet as the center-to-center distance between the two droplets was reduced, resulting in more spreading of the coalescing droplet.

Scordia D.,University of Catania | Cosentino S.L.,University of Catania | Lee J.-W.,Chonnam National University | Jeffries T.W.,U.S. Department of Agriculture | Jeffries T.W.,University of Wisconsin - Madison
Biomass and Bioenergy | Year: 2011

Biomass pretreatment is essential to overcome recalcitrance of lignocellulose for ethanol production. In the present study we pretreated giant reed (Arundo donax L.), a perennial, rhizomatous lignocellulosic grass with dilute oxalic acid. The effects of temperature (170-190 °C), acid loading (2-10% w/w) and reaction time (15-40 min) were handled as a single parameter, combined severity. We explored the change in hemicellulose, cellulose and lignin composition following pretreatment and glucan conversion after enzymatic hydrolysis of the solid residue. Two different yeast strains, Scheffersomyces (Pichia) stipitis CBS 6054, which is a native xylose and cellobiose fermenter, and Saccharomyces carlsbergensis FPL-450, which does not ferment xylose or cellobiose, were used along with commercial cellulolytic enzymes in simultaneous saccharification and fermentation (SSF). S. carlsbergensis attained a maximum ethanol concentration of 15.9 g/l after 48 h at pH 5.0, while S. stipitis, at the same condition, took 96 h to reach a similar ethanol value; increasing the pH to 6.0 reduced the S. stipitis lag phase and attained 18.0 g/l of ethanol within 72 h. © 2011 Elsevier Ltd.

Moon H.S.,Pusan National University | No H.-R.,Chonnam National University
Journal of the Optical Society of America B: Optical Physics | Year: 2014

We report the physical origins of the on-resonant and off-resonant two-photon absorption (TPA) in an open-laddertype atomic system of the 5S 1?2 (F = 1)-5P3?2(F0 = 0; 1; 2)-5D5?2(F00 =1; 2; 3) transitions in 87Rb atoms. When the onresonant TPA, including electromagnetically induced transparency (EIT), was transformed into the off-resonant TPA according to the coupling laser frequency detuning, we clarified the dynamics of the atomic coherences by decomposing into the two-photon coherence (TC) and the crossover coherence (CC) terms mixed between onephoton coherence (OC) and TC terms. The physical origins of the two TPAs were completely different; the cause of the on-resonant TPA was the CC term, and that of the off-resonant TPA was the TC term. © 2014 Optical Society of America.

Wang X.-L.,Chonnam National University | Oh I.-K.,Chonnam National University | Xu L.,Chonnam National University
Sensors and Actuators, B: Chemical | Year: 2010

In this study, a novel electro-active artificial muscle was developed with UV irradiation-crosslinked sulfonated poly(styrene-ran-ethylene) (XSPSE). The XSPSE ionic exchangeable membrane was crosslinked with vinyl silane by UV irradiation. The crosslinking mechanism between the SPSE backbone and vinyl silane was analyzed and checked by FT-IR spectra. AFM images showed that XSPSE membranes have better micro-phase separation morphology than pure SPSE membranes. Water uptake, ion exchange capacity, and sulfonation degree were characterized for both pure SPSE and silane crosslinked SPSE membranes. The electro-active bending responses of the XSPSE actuators under both direct current (DC) and alternating current (AC) excitations were investigated. The voltage-current behaviors of the actuators under AC excitations were also measured. Present results showed that the UV irradiation crosslinking method can greatly improve the actuation performance of SPSE artificial muscle. © 2010 Elsevier B.V. All rights reserved.

Moon H.S.,Pusan National University | Noh H.R.,Chonnam National University
Journal of Physics B: Atomic, Molecular and Optical Physics | Year: 2011

We have investigated the optical pumping effects of single-resonance optical pumping (SROP) and double-resonance optical pumping (DROP) in the ladder-type electromagnetically induced transparency (EIT) of the 5S 1/2-5P3/2-5D3/2 transition of 87Rb atoms. In the 5S1/2(F = 2)-5P3/2(F′ = 3)-5D 3/2(F″ = 2, 3) transition with the single-resonance cycling 5S1/2(F = 2)-5P3/2(F′ = 3) transition, we observed the transmittance spectrum due to DROP and EIT. Based on our experimental results investigated according to the laser power (the probe and the coupling) and the coupling laser detuning, we revealed that DROP was significant for the transmittance spectrum. Particularly, in the 5S1/2(F = 2)-5P 3/2(F′ = 1, 2)-5D3/2(F″ = 1) transition without a cycling transition, we observed the two-photon absorption due to two-photon atomic coherence, when the probe laser power was weak and the coupling laser power was strong. © 2011 IOP Publishing Ltd.

Byeon Y.,Chonnam National University | Back K.,Chonnam National University
Journal of Pineal Research | Year: 2015

Although melatonin biosynthetic genes from plants have been cloned, the melatonin catabolism mechanisms remain unclear. To clone the genes responsible for melatonin metabolism, we ectopically expressed 35 full-length cDNAs of rice 2-oxoglutarate-dependent dioxygenase (2-ODD) in Escherichia coli and purified the corresponding recombinant proteins. In vitro 2-ODD assays showed four independent 2-ODD proteins that were able to catalyze melatonin into 2-hydroxymelatonin, exhibiting melatonin 2-hydroxylase (M2H). These M2H proteins had peak activities at pH 8.0 and 30°C. The Km ranged from 121 μm to 371 μm with the Vmax ranging from 1.7 to 18.5 pkat/mg protein, respectively. The M2H enzyme activities were dependent on cofactors such as α-ketoglutarate, ascorbate, and Fe2+, similar to the 2-ODD enzymes. M2H activity was inhibited by prohexadione-Ca, an inhibitor of 2-ODD, in a dose-dependent manner. M2H activity was high in the roots of rice seedlings, concurrent with high transcription levels of 2-ODD 21, suggesting that 2-ODD 21 was a major gene for M2H activity. Analogous to the high M2H activity in the roots, 2-hydroxymelatonin was found in large quantities in roots treated with melatonin. These results suggest that melatonin was metabolized into 2-hydroxymelatonin by the M2H genes in plants, but the physiological significance of 2-hydroxymelatonin remains to be examined in the future. © 2015 John Wiley & Sons A/S.

Choi Y.-S.,Chonnam National University | Wu X.,Chonnam National University | Lee D.-W.,Chonnam National University
Review of Scientific Instruments | Year: 2014

In this study, we introduce a selective thermochemical nano-patterning method of graphene on insulating substrates. A tiny heater formed at the end of an atomic force microscope (AFM) cantilever is optimized by a finite element method. The cantilever device is fabricated using conventional micromachining processes. After preliminary tests of the cantilever device, nano-patterning experiments are conducted with various conducting and insulating samples. The results indicate that faster scanning speed and higher contact force are desirable to reduce the sizes of nano-patterns. With the experimental condition of 1 μm/s and 24 mW, the heated AFM tip generates a graphene oxide layer of 3.6 nm height and 363 nm width, on a 300 nm thick SiO2 layer, with a tip contact force of 100 nN. © 2014 AIP Publishing LLC.

Shin C.D.,Chonnam National University | Joo K.K.,Chonnam National University
Advances in High Energy Physics | Year: 2014

For over fifty years, reactor experiments have played an important role in neutrino physics, in both discoveries and precision measurements. One of the methods to verify the existence of neutrino is the observation of neutrino oscillation phenomena. Electron antineutrinos emitted from a reactor provide the measurement of the small mixing angle θ 13, providing rich programs of neutrino properties, detector development, nuclear monitoring, and application. Using reactor neutrinos, future reactor neutrino experiments, more precise measurements of θ 12, Δ m 12 2, and mass hierarchy will be explored. The precise measurement of θ 13 would be crucial for measuring the CP violation parameters at accelerators. Therefore, reactor neutrino physics will assist in the complete understanding of the fundamental nature and implications of neutrino masses and mixing. In this paper, we investigated several characteristics of RENO-50, which is a future medium-baseline reactor neutrino oscillation experiment, by using the GloBES simulation package. © 2014 Chang Dong Shin and Kyung Kwang Joo.

Kim S.,Chonnam National University
Fibers and Polymers | Year: 2011

A fabric drape shape database has been prepared to find the optimum combination of fabric physical properties for simulating the appearance of an actual fabric. First, an objective and quantitative evaluation method for the traditional Cusick drape tester has been devised. Then a virtual drape tester has been developed using an implicit integration based drape simulation engine to generate a series of virtually draped fabric with various physical properties. Finally, a search algorithm has been developed to find the optimum property combination for target fabric by comparing the simulated results with the Cusick drape tester result of that fabric. © 2011 The Korean Fiber Society and Springer Netherlands.

PURPOSE We aimed to evaluate the efficiency of placing an inferior vena cava (IVC) filter through the same popliteal vein access site used for percutaneous endovenous intervention in patients with extensive lower extremity deep vein thrombosis. METHODS This retrospective study included 21 patients who underwent IVC filter insertion through the popliteal vein over a three-year period. Patient medical records were reviewed for the location of the deep vein thrombosis, result of filter removal, and total number of endovascular procedures needed for filter insertion and recanalization of the lower extremity venous system. Follow-up lower extremity computed tomography (CT) venography was also reviewed in each patient to assess the degree of filter tilt in the IVC. RESULTS All patients had extensive lower extremity deep vein thrombosis involving the iliac vein and/or femoral vein. Seventeen patients showed deep vein thrombosis of the calf veins. In all patients, IVC filter insertion and the recanalization procedure were performed during a single procedure through the single popliteal vein access site. In the 17 patients undergoing follow-up CT, the mean tilt angle of the filter was 7.14°±4.48° in the coronal plane and 8.77°±5.49° in the sagittal plane. Filter retrieval was successful in 16 of 17 patients (94.1%) in whom filter retrieval was attempted. CONCLUSION Transpopliteal IVC filter insertion is an efficient technique that results in low rates of significant filter tilt and enables a single session procedure using a single venous access site for filter insertion and percutaneous endovenous intervention. © Turkish Society of Radiology 2016.

Jeong B.-C.,Chonnam National University | Kang I.-H.,Chonnam National University | Hwang Y.-C.,Chonnam National University | Kim S.-H.,Chonnam National University | Koh J.-T.,Chonnam National University
Cell Death and Disease | Year: 2014

Osteoblasts and adipocytes are differentiated from common mesenchymal stem cells (MSCs) in processes which are tightly controlled by various growth factors, signaling molecules, transcriptional factors and microRNAs. Recently, chicken ovalbumin upstream promoter-transcription factor II (COUP-TFII) was identified as a critical regulator of MSC fate. In the present study, we aimed to identify some microRNAs (miR), which target COUP-TFII, and to determine the effects on MSCs fate. During osteoblastic or adipocytic differentiation from MSCs lineage cells, miR-194 expression was found to be reversal. In the cultures of mesenchymal C3H10T1/2 and primary bone marrow stromal cells, osteogenic stimuli increased miR-194 expression with accompanying decreases in COUP-TFII expression, whereas adipogenic stimuli reduced miR-194 expression with accompanying increases in COUP-TFII expression. A luciferase assay with COUP-TFII 3′-untranslated region (UTR) reporter plasmid, including the miR-194 binding sequences, showed that the introduction of miR-194 reduced the luciferase activity. However, it did not affect the activity of mutated COUP-TFII 3′-UTR reporter. Enforced expression of miR-194 significantly enhanced osteoblast differentiation, but inhibited adipocyte differentiation by decreasing COUP-TFII mRNA and protein levels. In contrast, inhibition of the endogenous miR-194 reduced matrix mineralization in the MSCs cultures, promoting the formation of lipid droplets by rescuing COUP-TFII expression. Furthermore, overexpression of COUP-TFII reversed the effects of miR-194 on the cell fates. Taken together, our results showed that miR-194 acts as a critical regulator of COUP-TFII, and can determinate the fate of MSCs to differentiate into osteoblasts and adipocytes. This suggests that miR-194 and COUP-TFII may be good target molecules for controlling bone and metabolic diseases. © 2014 Macmillan Publishers Limited All rights reserved.

Oh P.-S.,Chonnam National University | Lim K.-T.,Chonnam National University
Inflammation | Year: 2011

The aim of the present study was to evaluate the inhibitory effect of glycoprotein isolated from Cudrania tricuspidata Bureau (CTB glycoprotein) on di(2-ethylhexyl) phthalate (DEHP)-induced allergic inflammatory response in mice. We evaluated the activity of â-hexosaminidase, expression of cyclooxygenase (COX)-2, p38 mitogen-activated protein kinase (MAPK), and activator protein (AP)-1, and production of immunoglobulin (Ig)E and interleukin (IL)-4 in DEHP-treated RBL-2H3 cells and ICRmice. Our results revealed that the CTB glycoprotein inhibited the activity of â-hexosaminidase and production of IgE and IL-4 in serum from DEHP-treated mice.We also found that the CTB glycoprotein reduced arachidonic acid release, COX-2 expression, and AP-1 transcriptional activation through p38 MAPK phosphorylation in DEHP-treated RBL-2H3 cells. The activation of AP-1 was completely blocked by treatment with p38 MAPK inhibitor (SKF86002). The results from these experiments indicate that CTB glycoprotein effectively protects against the allergic inflammation response, mainly through downregulation ofMAPK/AP-1 in the mast cell degranulation stage. In conclusion, we suggest that the CTB glycoprotein may be one component of health supplements for the prevention of allergic inflammation. © 2010 Springer Science+Business Media, LLC.

Kim Y.D.,Chonnam National University | Kim H.S.,Chonnam National University
Macromolecular Research | Year: 2013

The mono-dispersed polypyrrole (PPy)-poly(acrylonitrile-co-styrene) (SAN) copolymer particles were synthesized by emulsion polymerization and the electrorheological (ER) behavior of their suspensions was investigated. The suspensions of the mono-dispersed PPy-SAN copolymer particles showed negative ER effects. It was quite unexpected to negative ER effects for ER suspensions of conducting polymers or conducting polymer composites. The ER responses decreased with increasing electric field strength and particle size. A power-law dependence on the particle size and the electric field strength, τ(E)-τ0=-103.95 d -2 E, showed a reasonable fit to the dynamic yield stress differences. It was observed that particles separated between the electrodes during experiments under the applied electric field. The migrations due to charge injection, by which the gap between the electrodes devoid of particles, seem to play a role in the yield stress decrease, leading to the negative ER response. [Figure not available: see fulltext.] © 2013 The Polymer Society of Korea and Springer Sciene+Business Media Dordrecht.

Kalubarme R.S.,Chonnam National University | Kim Y.-H.,Chonnam National University | Park C.-J.,Chonnam National University
Nanotechnology | Year: 2013

A carbon nanotube (CNT)/cerium oxide composite was prepared by a one-pot hydrothermal reaction in the presence of KOH and capping agent polyvinylpyrrolidone. The nanocomposite displayed pronounced capacitive behaviour with very small diffusion resistance. The electrochemical performance of the composite electrode in a symmetric supercapacitor displayed a high energy density of 35.9 Wh kg-1 corresponding to a specific capacitance of 289 F g-1. These composite electrodes also demonstrated a long cycle life with better capacity retention. © 2013 IOP Publishing Ltd.

Lee H.-J.,Chonnam National University | Song J.-H.,Gwangju Institute of Science and Technology | Song J.-H.,Daegu Gyeongbuk Institute of Science and Technology | Moon S.-H.,Gwangju Institute of Science and Technology
Desalination | Year: 2013

In the present study, EDR (electrodialysis reversal) and EDIR (electrodeionization reversal), ion exchange membrane processes using periodic change of the polarity, were examined as water softening process. The LCD (limiting current density) was empirically determined as a function of linear flow velocity with different hardness concentrations in synthetic solutions. In addition, the influence of the LCD on the transport phenomena and water splitting were investigated. Accordingly, an appropriate operating current was selected for the constant current operation based on the LCD.The process performances of EDR and EDIR were compared for removal of hardness materials from a groundwater. Water softening performances of both EDR and EDIR processes were performed with various operation parameters including current density, flow velocity and hardness concentration. The EDIR process showed notably lower electric resistance and power consumption than the EDR process. The study showed that the EDIR process with an optimized constant current mode and periodic polarity change could be used as an effective water softening process by decreasing resistance and power consumption. © 2013.

Cho S.-H.,Chonnam National University | Yoon S.-D.,Chonnam National University | Byun H.-S.,Chonnam National University
Korean Journal of Chemical Engineering | Year: 2013

Pressure-composition isotherms are measured by using a static apparatus for the phase behavior data for the CO2+diethylene glycol diacrylate (DEGDA) and CO2+diethylene glycol dimethacrylate (DEGDMA) systems. The experiments are performed at five temperatures of (313. 2 to 393. 2) K and pressures up to 28. 3 MPa. The solubility of CO2 for the two systems decreases as the temperature increases at a fixed pressure. The CO2+DEGDA and CO2+ DEGDMA systems exhibit type-I phase behavior. The experimental results for the CO2+DEGDA and CO2+DEGDMA systems are correlated with Peng-Robinson equation of state using a mixing rule. © 2013 Korean Institute of Chemical Engineers, Seoul, Korea.

Jang H.-G.,Chonnam National University | Min H.-K.,Pohang University of Science and Technology | Hong S.B.,Pohang University of Science and Technology | Seo G.,Chonnam National University
Journal of Catalysis | Year: 2013

The reaction intermediates of methanol-to-olefin (MTO) conversion over phosphorous-modified HZSM-5 (P-MFI) catalysts were investigated by electron spin resonance (ESR) and gas chromatography-mass spectroscopy (GC-MS). Phosphorous modification partially neutralized the strong acid sites in HZSM-5. The phosphorous compounds suppress the migration of polymethylbenzenium radical cations, lowering spin-spin interactions and thus preserved their hyperfine splitting. The ESR spectra of the organic species formed in P-MFI zeolites during MTO conversion were similar to those of the cation species generated from 1,2,4,5-tetramethylbenzene in mordenite. GC-MS of organic extracts revealed the predominant formation of polymethylbenzenes with 4-6 methyl groups. The correlation between conversion and the number of spins of tetramethylbenzenium radical cations exhibited that these radical cations might be major active intermediates of MTO conversion over P-MFI catalysts. © 2012 Elsevier Inc. All rights reserved.

Lo P.-K.,University of South Carolina | Lee J.S.,Chonnam National University | Sukumar S.,Johns Hopkins University
Cellular Signalling | Year: 2012

We previously identified FOXF1 as a potential tumor suppressor gene with an essential role in preventing DNA rereplication to maintain genomic stability, which is frequently inactivated in breast cancer through the epigenetic mechanism. Here we further addressed the role of the p53-p21WAF1 checkpoint pathway in DNA rereplication induced by silencing of FOXF1. Knockdown of FOXF1 by small interference RNA (siRNA) rendered colorectal p53-null and p21WAF1-null HCT116 cancer cells more susceptible to rereplication and apoptosis than the wild-type parental cells. In parental HCT116 cells with a functional p53 checkpoint, the p53-p21WAF1 checkpoint pathway was activated upon FOXF1 knockdown, which was concurrent with suppression of the CDK2-Rb cascade and induction of G1 arrest. In contrast, these events were not observed in FOXF1-depleted HCT116-p53-/- and HCT116-p21-/- cells, indicating that the p53-dependent checkpoint function is vital for inhibiting CDK2 to induce G1 arrest and protect cells from rereplication. The pharmacologic inhibitor (caffeine) of ataxia telangiectasia mutated (ATM) and ataxia telangiectasia and Rad3 related (ATR) protein kinases abolished activation of the p53-p21WAF1 pathway upon FOXF1 knockdown, suggesting that suppression of FOXF1 function triggered the ATM/ATR-mediated DNA damage response. Cosilencing of p53 by siRNA synergistically enhanced the effect of FOXF1 depletion on the stimulation of DNA rereplication and apoptosis in wild-type HCT116. Finally, we show that FOXF1 expression is predominantly silenced in breast and colorectal cancer cell lines with inactive p53. Our study demonstrated that the p53-p21WAF1 checkpoint pathway is an intrinsically protective mechanism to prevent DNA rereplication induced by silencing of FOXF1. © 2011 Elsevier Inc.

Ahn T.,Chonnam National University | Yun C.-H.,Chonnam National University
Current Drug Metabolism | Year: 2010

Cytochrome P450 enzymes (CYPs) are a superfamily of monooxygenases found in almost all living organisms. CYPs are predominantly localized in the endoplasmic reticulum membranes as integral membrane proteins, where they metabolize a variety of endogenous and xenobiotic compounds. CYPs also reside in other subcellular compartments, including the plasma membranes and mitochondria. CYP localization in mitochondria is regulated in one of two ways: (1) direct targeting of inherent CYPs with canonical mitochondrial signals in their protein sequence after synthesis in the cytosol or (2) mitochondrial localization of microsomal CYPs after processing of the NH 2-terminal region. Microsomal CYPs targeted to mitochondria demonstrate conventional or altered catalytic activities using electrons provided by the mitochondrial electron transport system. Mechanisms of microsomal CYP targeting to mitochondria, regulation of localization, and the implications of these in drug metabolism are described in the present review. © 2010 Bentham Science Publishers Ltd.

Oh I.-J.,Chonnam National University | Ban H.-J.,Chonnam National University | Kim K.-S.,Chonnam National University | Kim Y.-C.,Chonnam National University
Lung Cancer | Year: 2012

Most patients with non-small-cell lung cancer (NSCLC) who initially respond to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) eventually experience progression of disease. Based on previous trials which showed second response after switching to another EGFR-TKI, we hypothesized that the reintroduction of gefitinib would lead to disease control rate (DCR) in more than 30% of patients. This was a single-arm, open-label, prospective, phase II trial of gefitinib for the treatment of advanced or metastatic NSCLC. Eligible patients had previously responded to, or had experienced disease stabilization with, initial gefitinib treatment for at least 3 months. Prior to retreatment, progressive disease (PD) should be observed, with at least one cytotoxic treatment following initial gefitinib failure. Twenty-three patients were recruited and defined as the intention to treat (ITT) group. Most of the enrolled patients were female (86.9%), never-smokers (91.3%), and adenocarcinoma patients (95.7%). Responses to initial gefitinib were partial response (PR) in 10 cases (43.5%) and stable disease (SD) in 13 cases (56.5%). PR and DCR were observed in 21.7% (5 patients) and 65.2% (15 patients) in the ITT group. Among 14 DNA samples, 13 cases had either exon 19 deletion or L858R point mutation, whereas one patient evidenced the wild-type EGFR gene. Re-initiation of EGFR-TKI can be considered as an option after failure of chemotherapy for those patients who previously controlled to EGFR-TKI treatment. © 2012 Elsevier Ireland Ltd.

Zheng F.,St Jude Childrens Research Hospital | Zhou X.,Nanjing Medical University | Moon C.,Chonnam National University | Wang H.,Michigan State University
International Journal of Physiology, Pathophysiology and Pharmacology | Year: 2012

Brain-derived neurotrophic factor (BDNF) plays critical roles in many aspects of brain functions, including cell survival, differentiation, development, learning and memory. Aberrant BDNF expression has also been implicated in numerous neurological disorders. Thus, significant effort has been made to understand how BDNF transcription as well as translation is regulated. Interestingly, the BDNF gene structure suggests that multiple promoters control its transcription, leading to the existence of distinct mRNA species. Further, the long-and short-tail of the 3′ un-translated region may dictate different sub-cellular BDNF mRNA targeting and translational responses following neuronal stimulation. This review aims to summarize the main findings that demonstrate how neuronal activities specifically up-regulate the transcription and translation of unique BDNF transcripts. We also discuss some of the recent reports that emphasize the epigenetic regulation of BDNF transcription.

Kim D.,Gwangju Institute of Science and Technology | Jeong Y.Y.,Chonnam National University | Jon S.,Gwangju Institute of Science and Technology
ACS Nano | Year: 2010

Computed tomography (CT) is one of the most useful diagnostic tools among commonly used biomedical imaging techniques, which also include magnetic resonance imaging (MRI), positron emission tomography (PET), and ultrasound. However, currently available CT contrast agents, which are based on small iodinated molecules, possess a number of limitations, including a lack of targeted molecular imaging, short imaging time, and renal toxicity. Here, we report a multifunctional nanoparticle for targeted molecular CT imaging and therapy of prostate cancer. By functionalizing the surface of gold nanoparticles (GNPs) with a prostate-specific membrane antigen (PSMA) RNA aptamer that binds to PSMA, we established a targeted molecular CT imaging system capable of specific imaging of prostate cancer cells that express the PSMA protein. The resulting PSMA aptamer-conjugated GNP showed more than 4-fold greater CT intensity for a targeted LNCaP cell than that of a nontargeted PC3 cell. Furthermore, the PSMA aptamer-conjugated GNPs after loading of doxorubicin were significantly more potent against targeted LNCaP cells than against nontargeted PC3 cells. © 2010 American Chemical Society.

Jung H.J.,Chonnam National University | Kang H.,Chonnam National University
Plant Journal | Year: 2014

Summary The U12-dependent introns have been identified in a wide range of eukaryotes and are removed from precursor-mRNAs by U12 intron-specific minor spliceosome. Although several proteins unique to minor spliceosome have been identified, the nature of their effect on U12 intron splicing as well as plant growth and development remain largely unknown. Here, we characterized the functional role of an U12-type spliceosomal protein, U11/U12-65K in Arabidopsis thaliana. The transgenic knockdown plants generated by artificial miRNA-mediated silencing strategy exhibited severe defect in growth and development, such as severely arrested primary inflorescence stems, serrated leaves, and the formation of many rosette leaves after bolting. RNA sequencing and reverse transcription polymerase chain reaction (RT-PCR) analyses revealed that splicing of 198 out of the 234 previously predicted U12 intron-containing genes and 32 previously unidentified U12 introns was impaired in u11/u12-65k mutant. Moreover, the U11/U12-65K mutation affected alternative splicing, as well as U12 intron splicing, of many introns. Microarray analysis revealed that the genes involved in cell wall biogenesis and function, plant development, and metabolic processes are differentially expressed in the mutant plants. U11/U12-65K protein bound specifically to U12 small nuclear RNA (snRNA), which is necessary for branch-point site recognition. Taken together, these results provide clear evidence that U11/U12-65K is an indispensible component of minor spliceosome and involved in U12 intron splicing and alternative splicing of many introns, which is crucial for plant development. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.

Chae H.Z.,Chonnam National University | Oubrahim H.,U.S. National Institutes of Health | Park J.W.,U.S. National Institute of Diabetes and Digestive and Kidney Diseases | Rhee S.G.,Ewha Womans University | Chock P.B.,U.S. National Institutes of Health
Antioxidants and Redox Signaling | Year: 2012

Reversible protein glutathionylation plays an important role in cellular regulation, signaling transduction, and antioxidant defense. This redox-sensitive mechanism is involved in regulating the functions of peroxiredoxins (Prxs), a family of ubiquitously expressed thiol-specific peroxidase enzymes. Glutathionylation of certain Prxs at their active-site cysteines not only provides reducing equivalents to support their peroxidase activity but also protects Prxs from irreversible hyperoxidation. Typical 2-Cys Prx also functions as a molecular chaperone when it exists as a decamer and/or higher molecular weight complexes. The hyperoxidized sulfinic derivative of 2-Cys Prx is reactivated by sulfiredoxin (Srx). In this review, the roles of glutathionylation in the regulation of Prxs are discussed with respect to their molecular structure and functions as antioxidants, molecular chaperones, and signal modulators. Recent Advances: Recent findings reveal that glutathionylation regulates the quaternary structure of Prx. Glutathionylation of Prx I at Cys 83 converts the decameric Prx to its dimers with the loss of chaperone activity. The findings that dimer/oligomer structure specific Prx I binding proteins, e.g., phosphatase and tensin homolog (PTEN) and mammalian Ste20-like kinase-1 (MST1), regulate cell cycle and apoptosis, respectively, suggest a possible link between glutathionylation and those signaling pathways. Critical Issues: Knowing how glutathionylation affects the interaction between Prx I and its nearly 20 known interacting proteins, e.g., PTEN and MST1 kinase, would reveal new insights on the physiological functions of Prx. Future Directions: In vitro studies reveal that Prx oligomerization is linked to its functional changes. However, in vivo dynamics, including the effect by glutathionylation, and its physiological significance remain to be investigated. © 2012, Mary Ann Liebert, Inc.

Kumar M.R.,Chonnam National University | Irudayanathan F.M.,Chonnam National University | Moon J.H.,Florida International University | Lee S.,Chonnam National University
Advanced Synthesis and Catalysis | Year: 2013

Copper-catalyzed coupling reaction of 2-iodobenzoic acids and alkynes such as terminal acetylenes, alkynyl carboxylic acids, and trimethylsilylacetylene selectively afforded isocoumarins and phthalides in the presence of cesium carbonate (Cs2CO3) and dimethyl sulfoxide (DMSO). Among the regioselective products, only the 6-endo-dig product, isocoumarin, was formed at 100 °C, and the 5-exo-dig product, phthalide, was formed as a major product at 25 °C. A variety of alkynes produced the corresponding isocoumarins and phthalides in good yields. A mechanism is suggested in which the formation of 2-alkynylbenzoic acid as an intermediate via Sonogashira-type coupling was ruled out in the reaction pathway. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nguyen V.H.,Chonnam National University | Gu H.-B.,Chonnam National University
Journal of Applied Electrochemistry | Year: 2014

In this study, graphene was added to LiFePO4 via a hydrothermal method to improve the lithium-ion-diffusion ability of LiFePO4. The influence of graphene addition on LiFePO4 was studied by X-ray diffraction (XRD), field emission scanning electron microscopy, transmission electron microscopy, cyclic voltammetry, cycling test, and AC impedance analysis. The addition of graphene to LiFePO4 resulted in the formation of a LiFePO4–graphene composite; XRD observations revealed the composite to have a single phase with an olivine-type structure. Furthermore, LiFePO4 particles in the composite were stacked on the graphene sheet surface, thereby enabling the composite to form an effective conducting network and facilitate the penetration of the surface of active materials by an electrolyte. The lithium-ion-diffusion ability of the LiFePO4–graphene composite was greater than that of pure LiFePO4. Of a number of materials studied [namely, pure LiFePO4, LiFePO4–graphene (1 %), LiFePO4–graphene (5 %), and LiFePO4–graphene (8 %)], LiFePO4–graphene (5 %) delivered the best electrochemical performance with a lithium-ion-diffusion coefficient of 8.18 × 10−12 cm2 s−1 and the highest specific discharge capacity of 149 mAh g−1 at 0.17 C; in contrast, the corresponding values for pure LiFePO4 were 3.01 × 10−12 cm2 s−1 and 109 mAh g−1, respectively. Further, LiFePO4–graphene (5 %) showed a very high specific discharge capacity of 170 mAh g−1 at 0.1 C, which is equal to the theoretical capacity of LiFePO4. © 2014, Springer Science+Business Media Dordrecht.

Kim T.-H.,Chonnam National University | Kang H.-K.,Chonnam National University | Jeong G.-W.,Chonnam National University
Journal of Sexual Medicine | Year: 2013

Introduction: Numerous functional magnetic resonance imaging (fMRI) studies demonstrated the key brain areas associated with visual sexual arousal. However, the changes in brain metabolites involved in sexual stimuli have not been reported. Aim: This study utilized functional MR spectroscopy (fMRS) to evaluate the changes in brain metabolites associated with sexual arousal induced by stimulation with erotic video clips in healthy women. Methods: Twenty-three healthy, right-handed women (38.4±10.0years) participated in 1H-fMRS and fMRI studies. T1 and T2 MR images were used for voxel localization of the anterior cingulate gyrus, which is one of the most important key centers associated with sexual arousal. Main Outcome Measures: The changes of brain metabolites were measured using 1H-fMRS during time-course activation: "before," "during," and "after" visual sexual stimulation. The time-course variation of the brain metabolites was analyzed by the repeated-measures analysis of variance. Results: The CVmean of all the metabolites had <30% (range, 9-29%). The ICCs of α-glutamine-glutamate (Glx), choline (Cho), β·γ-Glx, N-acetylaspartate (NAA) and lactate (Lac) all exceeded 0.6. However, myo-inositol (mI) and lipid (Lip) were <0.6. The concentration of brain metabolites including α-Glx, β·γ-Glx, Cho, and Lac comparatively increased significantly during visual sexual stimulation. Conclusions: 1H-fMRS, for the first time, was applied to assess the brain metabolic changes during visually-evoked sexual arousal. The fMRS outcomes in relation to functional MRI data will be useful to understand the neural mechanism associated with sexual arousal. © 2013 International Society for Sexual Medicine.

Expression of Livin, a member of the inhibitors of apoptosis protein family, is associated with tumor development and progression. The aims of this study were to evaluate whether Livin affects oncogenic biological behavior of colorectal cancer cells, and to document the relationship between its expression and various clinicopathological parameters in colorectal cancer. We investigated the impact of Livin on tumor cell behavior by using the small interfering RNA and pcDNA3.1 vector in SW480 and DKO1 colorectal cancer cell lines. The expression of Livin was investigated by RT-PCR and immunohistochemistry in coloretcal cancer tissues. The apoptotic cells were visualized by TUNEL assay, and proliferative cells were visualized by Ki-67 antibody staining. Knockdown of Livin suppressed tumor cell migration and invasion in colorectal cancer cells. Knockdown of Livin induced the apoptosis by up-regulating of caspase-3, -7 and PARP activities and the cell cycle arrest by decreasing cyclin D1, cyclin D3, cyclin-dependent kinase 4 and 6, and by inducing p27 expression. The MAPK signaling cascades were significantly blocked by knockdown of Livin. In contrast, overexpression of Livin enhanced tumor cell migration and invasion, and inhibited the apoptosis and cell cycle arrest. The mean apoptotic index (AI) value of Livin positive tumors was significantly lower than AI of Livin negative tumors. However, there was no significant difference between Livin expression and Ki-67 labeling index (KI). Livin expression was significantly increased in colorectal cancer and metastatic lymph node tissues compared to normal colorectal mucosa and non-metastatic lymph node tissues and was associated with tumor stage, lymphovascular invasion, lymph node metastasis and poor survival. These results indicate that Livin is associated with tumor progression by increasing tumor cell motility and inhibiting apoptosis in colorectal cancer.

Park K.,Chonnam National University | Kwak I.-S.,Chonnam National University
Chemosphere | Year: 2010

Endocrine-disrupting chemicals (EDCs) mimic the action of endogenous estrogen hormones; consequently, they can interfere with the endocrine systems of a variety of organisms. There is global concern regarding the potential impacts of EDCs on the aquatic environment. To evaluate the effects of EDCs on the estrogen-related receptors (ERR) of Chironomus, we characterized full-length cDNA sequences of the ERR gene from Chironomus riparius. The complete cDNA sequence of the ERR gene was found to be 1332 bp in length. The results of our phylogenetic analysis demonstrated that C. riparius ERR was most closely related to that of mosquitoes. The basal level of ERR mRNA was expressed abundantly during different life-history stages, with the exception of adult males. Additionally, ERR gene expression was upregulated significantly in C. riparius exposed to bisphenol A (BPA) and 4-nonylphenol (NP) at all concentrations assayed after 24 h of exposure. The ERR gene was significantly upregulated following short periods of exposure to di(2-ethylhexyl)phthalate (DEHP) concentrations of only 50 mg L -1. However, under long-term exposure conditions, ERR expression was induced to a significant degree after BPA, NP, and DEHP exposure at all concentrations assayed. Furthermore, the luciferase reporter gene assay revealed increased ERR expression following exposure to these compounds. Collectively, these findings indicate that EDCs influence the expression of ERR in Chironomus species. © 2010 Elsevier Ltd. All rights reserved.

Ryu H.S.,Chonnam National University
The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi | Year: 2010

Acute hepatitis A was recently significant increased among women with gestational age in Korea. However, the clinical course and gestational complications have not been fully elucidated in pregnant patients with acute hepatitis A. We evaluated the clinical impact of acute HAV infection in pregnancy. Twelve pregnant women out of 85 female patients with acute hepatitis A during 6 years were retrospectively reviewed. Results: The median age of the pregnant group was 26.5 years old. The number of patient with acute hepatitis A were 5 cases in the 1st trimester, 3 cases in the 2nd and 4 cases in the 3rd. 4 cases had significant gestational complications. One case experienced the abortion in 1st trimester and one fetal distress was noted in 3rd trimester. The latter case was delivered of a low birth weight infant (2,390 g) caused by premature rupture of membrane in 36 weeks of gestational age. Other two cases experienced premature contraction and they had been required tocolytic treatment. But, all mothers featured full recovery from HAV infection. Except one aborted fetus and one premature birth, Newborn babies were not affected by maternal hepatitis A. Acute HAV infection during pregnancy may be associated with the risk of gestational complications. HAV serology and vaccination for women with gestation age should be considered at high prevalence area of acute hepatitis A.

Karthikeyan K.,Chonnam National University | Kalpana D.,CSIR - Central Electrochemical Research Institute | Amaresh S.,Chonnam National University | Lee Y.S.,Chonnam National University
RSC Advances | Year: 2012

Pristine Fe3O4 and Fe3O 4-graphene composites were synthesized by using a green and low cost urea-assisted microwave irradiation method and were utilized as electrode materials for symmetric supercapacitor applications. The Fe3O 4-graphene symmetric cell exhibited a better electrochemical performance than that of the Fe3O4 cell with enhanced rate performances. The Fe3O4-graphene symmetric cell delivered a stable discharge capacitance, energy and power densities of about 72 F g -1, 9 Wh kg-1 and 3000 W kg-1, respectively at 3.75 A g-1 current density over 100/000 cycles between 0-1 V. The impedance studies also suggested that the Fe3O4-graphene symmetric cell showed lower resistance and high conductivity due to the small particle size, large surface area and good interaction between Fe 3O4 particles and graphene layers. © 2012 The Royal Society of Chemistry.

Choi Y.,Pohang University of Science and Technology | Lee Y.,Pohang University of Science and Technology | Kim S.Y.,Chonnam National University | Hwang J.-U.,Pohang University of Science and Technology
Plant, Cell and Environment | Year: 2013

Auxin and abscisic acid (ABA) modulate numerous aspects of plant development together, mostly in opposite directions, suggesting that extensive crosstalk occurs between the signalling pathways of the two hormones. However, little is known about the nature of this crosstalk. We demonstrate that ROP-interactive CRIB motif-containing protein 1 (RIC1) is involved in the interaction between auxin- and ABA-regulated root growth and lateral root formation. RIC1 expression is highly induced by both hormones, and expressed in the roots of young seedlings. Whereas auxin-responsive gene induction and the effect of auxin on root growth and lateral root formation were suppressed in the ric1 knockout, ABA-responsive gene induction and the effect of ABA on seed germination, root growth and lateral root formation were potentiated. Thus, RIC1 positively regulates auxin responses, but negatively regulates ABA responses. Together, our results suggest that RIC1 is a component of the intricate signalling network that underlies auxin and ABA crosstalk. © 2012 Blackwell Publishing Ltd.

Lee H.Y.,Chonnam National University | Byeon Y.,Chonnam National University | Tan D.-X.,University of Texas Health Science Center at San Antonio | Reiter R.J.,University of Texas Health Science Center at San Antonio | Back K.,Chonnam National University
Journal of Pineal Research | Year: 2015

Serotonin N-acetyltransferase (SNAT) is the penultimate enzyme in the melatonin biosynthesis pathway in plants. We examined the effects of SNAT gene inactivation in two Arabidopsis T-DNA insertion mutant lines. After inoculation with the avirulent pathogen Pseudomonas syringe pv. tomato DC3000 harboring the elicitor avrRpt2 (Pst-avrRpt2), melatonin levels in the snat knockout mutant lines were 50% less than in wild-type Arabidopsis Col-0 plants. The snat knockout mutant lines exhibited susceptibility to pathogen infection that coincided with decreased induction of defense genes including PR1, ICS1, and PDF1.2. Because melatonin acts upstream of salicylic acid (SA) synthesis, the reduced melatonin levels in the snat mutant lines led to decreased SA levels compared to wild-type, suggesting that the increased pathogen susceptibility of the snat mutant lines could be attributed to decreased SA levels and subsequent attenuation of defense gene induction. Exogenous melatonin treatment failed to induce defense gene expression in nahG Arabidopsis plants, but restored the induction of defense gene expression in the snat mutant lines. In addition, melatonin caused translocation of NPR1 (nonexpressor of PR1) protein from the cytoplasm into the nucleus indicating that melatonin-elicited pathogen resistance in response to avirulent pathogen attack is SA-dependent in Arabidopsis. © 2015 John Wiley & Sons A/S.

Jeon J.,Chonnam National University | Kim J.,Chonnam National University
Plant Physiology | Year: 2013

The Arabidopsis (Arabidopsis thaliana) two-component signaling system, which is composed of sensor histidine kinases, histidine phosphotransfer proteins, and response regulators, mediates the cytokinin response and various other plant responses. We have previously shown that ARABIDOPSIS HISTIDINE KINASE2 (AHK2), AHK3, and cold-inducible type A ARABIDOPSIS RESPONSE REGULATORS (ARRs) play roles in cold signaling. However, the roles of type B ARRs and ARABIDOPSIS HISTIDINE PHOSPHOTRANSFER PROTEINS (AHPs) have not been investigated in cold signaling. Here, we show that ARR1 and AHP2, AHP3, and AHP5 play positive roles in the cold-inducible expression of type A ARRs. arr1 mutants showed greatly reduced coldresponsive expression of type A ARRs compared with the wild type, whereas ARR1-overexpressing Arabidopsis exhibited the hypersensitive cold response of type A ARRs as well as enhanced freezing tolerance with cytokinin, suggesting that ARR1 functions as a positive factor of cold signaling. Transgenic Arabidopsis expressing ARR1ΔDDK:GR lacking the amino-terminal receiver domain showed wild-type expression levels of type A ARRs in response to cold, indicating that the signal receiver domain of ARR1 might be important for cold-responsive expression of type A ARRs. ahp2 ahp3 ahp5 triple mutations greatly reduced type A ARR expression in response to cold, whereas the single or double ahp mutants displayed wild-type levels of ARR expression, suggesting that AHP2, AHP3, and AHP5 are redundantly involved in cold signaling. Taken together, these results suggest that ARR1mediates cold signal via AHP2, AHP3, or AHP5 from AHK2 and AHK3 to express type A ARRs. We further identified a cold transcriptome affected by ahk2 ahk3 mutations by microarray analysis, revealing a new cold-responsive gene network regulated downstream of AHK2 and AHK3. © 2012 American Society of Plant Biologists. All Rights Reserved.

Chung C.Y.,Chonnam National University
The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi | Year: 2012

Kaposi sarcoma (KS) is a vascular neoplasm, which is fairly prevalent in acquired immunodeficiency syndrome (AIDS) patients. Mucocutaneous and lymph node involvements are characteristic features of KS in AIDS patients. The involvement of gastrointestinal tract occurs in 40% of KS patients and leads to significant morbidity and mortality. In the highly active antiretroviral therapy (HAART) era, the rate of AIDS related KS has fallen with control of human immunodeficiency virus (HIV) viremia. However, it is still recognized as the primary AIDS-defining illness, and the proportion of AIDS diagnoses made due to KS ranged from 4.1% to 7.5%. In Korea, AIDS-related KS has been report in low rate incidence. Its gastrointestinal involvements are rarely reported. To date, five cases have been recorded in Korea. Herein, we present an additional case of gastrointestinal KS as the AIDS-defining illness and review of the Korean medical literature.

Meng X.,University of Missouri | Xu J.,Zhejiang University | He Y.,University of Missouri | Yang K.-Y.,Chonnam National University | And 5 more authors.
Plant Cell | Year: 2013

Arabidopsis thaliana MPK3 and MPK6, two mitogen-activated protein kinases (MAPKs or MPKs), play critical roles in plant disease resistance by regulating multiple defense responses. Previously, we characterized the regulation of phytoalexin biosynthesis by Arabidopsis MPK3/MPK6 cascade and its downstream WRKY33 transcription factor. Here, we report another substrate of MPK3/MPK6, ETHYLENE RESPONSE FACTOR6 (ERF6), in regulating Arabidopsis defense gene expression and resistance to the necrotrophic fungal pathogen Botrytis cinerea. Phosphorylation of ERF6 by MPK3/MPK6 in either the gain-of-function transgenic plants or in response to B. cinerea infection increases ERF6 protein stability in vivo. Phospho-mimicking ERF6 is able to constitutively activate defense-related genes, especially those related to fungal resistance, including PDF1.1 and PDF1.2, and confers enhanced resistance to B. cinerea. By contrast, expression of ERF6-EAR, in which ERF6 was fused to the ERF-associated amphiphilic repression (EAR) motif, strongly suppresses B. cinerea-induced defense gene expression, leading to hypersusceptibility of the ERF6-EAR transgenic plants to B. cinerea. Different from ERF1, the regulation and function of ERF6 in defensin gene activation is independent of ethylene. Based on these data, we conclude that ERF6, another substrate of MPK3 and MPK6, plays important roles downstream of the MPK3/MPK6 cascade in regulating plant defense against fungal pathogens. © 2013 American Society of Plant Biologists. All rights reserved.

You J.-M.,Chonnam National University | Kim D.,Chonnam National University | Jeon S.,Chonnam National University
Electrochimica Acta | Year: 2012

Glassy carbon electrodes were coated with thiolated carbon nanostructures - multi-walled carbon nanotubes and graphene oxide. The subsequent covalent addition of platinum nanoparticles and coating with poly(diallydimethylammonium chloride) resulted in biosensors that detected hydrogen peroxide through its electrocatalytic reduction. The sensors were easily and quickly prepared and showed improved sensitivity to the electrocatalytic reduction of H 2O 2. The Pt nanoparticles covalently bonded to the thiolated carbon nanostructures were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, and energy dispersive X-ray spectroscopy. Cyclic voltammetry and amperometry were used to characterize the biosensors' performances. The sensors exhibited wide linear ranges and low detection limits, giving fast responses within 10 s, thus demonstrating their potential for use in H 2O 2 analysis. © 2012 Elsevier Ltd. All rights reserved.

Kang L.-J.,Chonnam National University | Choi Y.-J.,Chonnam National University | Lee S.-G.,Chonnam National University
International Journal of Biochemistry and Cell Biology | Year: 2013

In present study, we investigated the effect of ginsenoside Rg3 on hepatitis B virus DNA replication and secretion of hepatitis B surface antigen and e antigen in HepG2.2.15 cells. Rg3 dose- and time-dependently inhibited hepatitis B surface antigen, e antigen, and hepatitis B viral particle secretion. To explore the effect of Rg3 on anti-hepatitis B activity, we analysed toll-like receptor-myeloid differentiation primary response gene 88 signalling. Rg3 did not affect the expression of toll-like receptors or myeloid differentiation primary response gene 88. However, it significantly inhibited the expression of TNF receptor-associated factor 6 and transforming growth factor β activated kinase-1, which are adaptor molecules that signal through a toll-like receptor-myeloid differentiation primary response gene 88-dependent pathway. The inhibitory effect of Rg3 on TNF receptor-associated factor 6/transforming growth factor β activated kinase-1 expression was caused by the downregulation of TNF receptor-associated factor 6 expression as well as the stimulation of ubiquitination and proteasomal degradation of TNF receptor-associated factor 6, followed by downregulation of transforming growth factor β activated kinase-1. Furthermore, Rg3 inhibited mitogen-activated protein kinase signalling by inhibiting c-Jun N-terminal kinase phosphorylation, reduced the expression of AP-1 transcription factors (especially c-Jun and JunB), and inhibited AP-1 promoter activity. The inhibitory effect of Rg3 on c-Jun N-terminal kinase/AP-1 signalling showed anti-inflammatory activity based on the reduction in the expression of pro-inflammatory cytokines, IL-8 and TNF-α, at both the transcriptional and translational levels. Therefore, Rg3 showed anti-hepatitis B activity via the degradation of TNF receptor-associated factor 6/transforming growth factor β activated kinase-1 and the inhibition of c-Jun N-terminal kinase/AP-1 signalling. © 2013 Elsevier B.V. All rights reserved.

Tong J.,Chonnam National University | Yang H.,Chonnam National University | Yang H.,University of New South Wales | Eom S.H.,Gwangju Institute of Science and Technology | Im Y.J.,Chonnam National University
Structure | Year: 2013

The oxysterol-binding protein (OSBP)-related proteins (ORPs) are conserved from yeast to humans, and implicated in the regulation of lipid homeostasis and in signaling pathways. Saccharomyces cerevisiae has seven ORPs (Osh1-Osh7) that share one unknown essential function. Here, we report the 1.5-2.3 Å structures of the PH domain and ORD (OSBP-related domain) of yeast Osh3 in apo-form or in complex with phosphatidylinositol 4-phosphate (PI[4]P). Osh3 recognizes PI(4)P by the highly conserved residues in the tunnel of ORD whereas it lacks sterol binding due to the narrow hydrophobic tunnel. Yeast complementation tests suggest that PI(4)P binding to PH and ORD is essential for function. This study suggests that the unifying feature in all ORP homologs is the binding of PI(4)P to ORD and sterol binding is additional to certain homologs. Structural modeling of full-length Osh3 is consistent with the concept that Osh3 is a lipid transfer protein or regulator in membrane contact sites. © 2013 Elsevier Ltd.

Kang K.,Chonnam National University | Kang K.,Michigan State University | Lee K.,Chonnam National University | Park S.,Chonnam National University | And 2 more authors.
Journal of Pineal Research | Year: 2013

Because of the absence of an arylalkylamine N-acetyltransferase (AANAT) homolog in the plant genome, the proposal was made that a GCN5- related N-acetyltransferase superfamily gene (GNAT) could be substituted for AANAT. To clone rice serotonin N-acetyltransferase (SNAT), we expressed 31 rice GNAT cDNAs in Escherichia coli and screened SNAT activity by measuring N-acetyltryptamine after application with 1 mM tryptamine. GNAT5 was shown to produce high levels of N-acetyltryptamine in E. coli, suggesting a possible rice SNAT. To confirm SNAT activity, the GNAT5 protein was purified through affinity purification from E. coli culture. The purified recombinant GNAT5 showed high SNAT enzyme activity catalyzing serotonin into N-acetylserotonin. The values for Km and Vmax were 385 lM and 282 pmol/min/mg protein, respectively. An in vitro enzyme assay of purified SNAT showed N-acetylserotonin formation to be proportional to enzyme concentration and time, with peak activity at pH 8.8. High substrate concentrations above 1 mM serotonin inhibited SNAT activity. Finally, the mRNA level of SNAT was higher in shoots than in roots, but it was expressed constitutively, unlike N-acetylserotonin methyltransferase (ASMT), the terminal enzyme in melatonin synthesis. These results suggest that ASMT rather than SNAT is the rate-limiting enzyme of melatonin biosynthesis in plants. © 2012 John Wiley & Sons A/S.

Jeong Y.N.,Chonnam National University | Choi M.Y.,Gyeongsang National University | Choi H.C.,Chonnam National University
Electrochimica Acta | Year: 2012

Pt- and Pd-decorated carbon nanotubes (CNTs) have been prepared by diimide-activated amidation, an approach that avoids the harmful products of conventional SOCl 2 treatment. In this study, N,N′- dicyclohexylcarbodiimide (DCC) was used as a coupling agent for the formation of an amide linkage. According to ICP measurements, the resulting materials consist of 7.1 wt.% loaded Pt and 8.6 wt.% loaded Pd. The TEM images show that size-similar and quasi-spherical nanoparticles are highly dispersed along the entire CNT walls. The prepared Pt-CNT exhibited an especially high oxidation current toward methanol, formic acid, and formaldehyde compared with that of the pristine CNT and a Pt/CNT mixture (10 wt.% Pt). Furthermore, the Pd-CNT displayed higher activity toward H 2O 2 reduction than that of the reference systems. The better catalytic activities can be explained by the high electrochemically active surface area that resulted from the smaller size and excellent dispersion of metal nanoparticles on CNT. These results demonstrate the DCC-activated amidation to be a very effective and useful way to tune size and disperse metal species in metal-decorated CNTs, markedly improving their catalytic activity. © 2011 Elsevier Ltd. All rights reserved.

Kim B.-H.,Chonnam National University | Yang K.S.,Chonnam National University | Woo H.-G.,Chonnam National University
Electrochimica Acta | Year: 2012

Polyacrylonitrile (PAN)/polyphenylsilane (PPS)-based composite carbon nanofibers (CCNFs) are prepared by one-step electrospinning and subsequent thermal treatment to produce organic-inorganic hybrid CCNFs. We investigate the electrochemical behavior and structural properties of these CCNF materials as a function the PAN/PPS ratio. The CCNFs show large specific surface area, high electrical conductivity and high thermal stability. In addition, the electrochemical performance of the organic-inorganic hybrid CCNF electrode is improved by the special porous structure and the silicon oxycarbide (Si-O-C)-related structure. © 2011 Elsevier Ltd. All Rights Reserved.

Kim H.-E.,Chonnam National University | Lee S.-G.,Chonnam National University
International Journal of Biochemistry and Cell Biology | Year: 2013

Hydrogen peroxide (H2O2) production due to oxidative stress is associated with apoptosis and melanogenesis in melanocytes. Here, we analyzed the effects of H2O2 on melanogenesis by measuring the melanin content and analyzing the expression of melanogenesis-related proteins, including cAMP-responsive element binding protein (CREB), microphthalmia-associated transcription factor (MITF), tyrosinase (TYR), and phenylalanine hydroxylase (PAH). Treatment with 1 mM H2O2 increased the cellular melanin content; the expression of PAH, TYR, and MITF; and the phosphorylation of CREB in B16F10 and SK-Mel-2 cells. In addition, H2O2 increased the expression of ATP synthase β (ATP5B), a mitochondrial F1 complex, and increased intracellular ATP levels. Studies using the ATP5B inhibitor oligomycin (OM) showed that the induction of cAMP resulted from an increase in ATP caused by the induction of ATP5B. OM treatment increased H2O2-mediated apoptosis via accelerated ATP depletion and apoptosis-related gene expressions. In summary, H2O2 may induce melanogenesis via the upregulation of PAH and activation of cAMP/p-CREB/MITF signaling by increasing intracellular cAMP levels through the induction of ATP5B. © 2013 Elsevier Ltd.

Lee M.-G.,Chonnam National University | Kang K.-J.,Chonnam National University
International Journal of Mechanical Sciences | Year: 2014

The strength and stiffness of WBC (Wire-woven Bulk Cross) in two different orientations was investigated under shear load to evaluate its feasibility as a metallic sandwich core material. Analytic solutions were derived, and experiments were performed using specimens fabricated from stainless steel wires. And also, finite element simulations were performed to analyze the experimental results. WBC with X-orientation showed that the lower limit of relative density at which WBC resists shear loading can be as low as 1%, and the shear strength and modulus for a given weight were much higher than other two wire-woven metals. The WBC with X-orientation has statically indeterminate structure without face sheets, but the specific shear strengths and moduli are comparable and somewhat inferior to those of aluminum honeycombs. Moreover, the interior space of WBC can serve various functions such as storage or passage of fluids. © 2014 Elsevier Ltd.

Le T.-H.,Chonnam National University | Jeong H.-D.,Chonnam National University
Physical Chemistry Chemical Physics | Year: 2014

Optical properties of silicon quantum dots (Si QDs) are greatly influenced by their size and surface chemistry. We report the micro-emulsion synthesis of hydrogen terminated Si QDs, with the modification of quenching the remaining reducing agent LiAlH4 with CuSO4. Subsequent functionalization was carried out with different capping molecules, including 1-octene, phenylacetylene, and 1,4-diethynylbenzene, to give octyl, styryl, and 4-ethynylstyryl terminated silicon quantum dots, respectively. The optical properties of the three kinds of Si QD synthesized, with the extended conjugation length, were examined. The effects of surface chemistry on the optical properties of the Si QD, obtained using ultraviolet-visible absorption spectroscopy and photoluminescence spectroscopy, were compared to the extension of electron and hole wavefunctions into the capping molecules, which were estimated from modified particles in a box calculation. The observed quantum yield increased from 2% to 2.5% and 9.0% and the average lifetime decreased with increasing conjugation length of the octyl Si QD, the styryl Si QD, and the 4-ethynylstyryl Si QD, which were ascribed to the effect of electronic coupling between the capping molecules and the Si QD. A tentative model in which the strong electronic interaction through covalent bonding induced a more direct band gap character for light emission was proposed by tuning the ground state wavefunctions of the electron and hole in wave vector space. © the Partner Organisations 2014.

Nguyen Q.P.B.,Chonnam National University | Kim J.N.,Chonnam National University | Kim T.H.,Chonnam National University
Tetrahedron | Year: 2012

The reduction of conjugated nitroalkenes into nitroalkanes with Hantzsch ester using S-benzyl isothiouronium chloride as a recoverable organocatalyst was successfully accomplished with high yield and excellent chemoselectivity. © 2012 Elsevier Ltd. All rights reserved.

Park S.,Chonnam National University | Byeon Y.,Chonnam National University | Kim Y.-S.,Chonnam National University | Back K.,Chonnam National University
Journal of Pineal Research | Year: 2013

Rice (Oryza sativa) N-acetylserotonin methyltransferase (osASMT), the last enzyme in the synthesis of melatonin, was expressed in Escherichia coli and purified. We then characterized its enzyme kinetics, which is the first time this has been performed in plants. Purified glutathione S-transferase (GST)-fused recombinant osASMT (GST-osASMT) and GST-free osASMT showed specific enzyme activities of 6.6 and 12.6 pmol/min per mg protein, respectively. When evaluated by the Lineweaver-Burk equation, GST-free osASMT exhibited a K m of 864 μm. An in vitro enzyme assay of purified osASMT showed melatonin formation to be proportional to the enzyme and substrate concentrations, as well as time. Unlike animal ASMT, high substrate concentrations did not inhibit the activity of osASMT. Finally, melatonin biosynthesis in rice seedlings was affected by light intensity, with etiolated shoots grown in continuous darkness producing more melatonin than shoots grown in continuous light. The level of melatonin in relation to the light intensity closely paralleled the mRNA level of osASMT in the shoots, suggesting that endogenous melatonin is upregulated in darkness, as is the case in animals. © 2012 John Wiley & Sons A/S.

Ma L.S.,Lanzhou University of Technology | Ma L.S.,Chonnam National University | Lee D.W.,Chonnam National University
European Journal of Mechanics, A/Solids | Year: 2012

An exact, closed-form solution is obtained for the nonlinear static responses of beams made of functionally graded materials (FGM) subjected to a uniform in-plane thermal loading. The equations governing the axial and transverse deformations of FGM beams are derived based on the nonlinear first-order shear deformation beam theory and the physical neutral surface concept. The three equations are reduced to a single nonlinear fourth-order integral-differential equation governing the transverse deformations. For a fixed-fixed FGM beam, the equation and the corresponding boundary conditions lead to a differential eigenvalue problem, while for a hinged-hinged FGM beam, an eigenvalue problem does not arise due to the inhomogeneous boundary conditions, which result in quite different behavior between clamped and simply supported FGM beams. The nonlinear equation is directly solved without any use of approximation and a closed-form solution for thermal post-buckling or bending deformation is obtained as a function of the applied thermal load. The exact solutions explicitly describe the nonlinear equilibrium paths of the deformed beam and thus are able to provide insight into deformation problems. To show the influence of the material gradients, transverse shear deformation, in-plane loading, and boundary conditions, numerical examples are given based on exact solutions, and some properties of the post-buckling and bending responses of FGM beams are discussed. The exact solutions obtained herein can serve as benchmarks to verify and improve various approximate theories and numerical methods. © 2011 Elsevier Masson SAS. All rights reserved.

Chung K.-H.,Chonnam National University
Energy | Year: 2010

Hydrogen storage on microporous zeolites was examined using a high pressure dose of hydrogen at 30 °C. The roles of the framework structure, surface area, and pore volume of the zeolites on hydrogen adsorption were investigated. The largest hydrogen storage was obtained on the ultra stable Y (USY) zeolite (0.4 wt%). The hydrogen adsorption isotherms on the zeolites reached a maximum after a hydrogen pressure of 50 bar. The amount of hydrogen adsorption on Mordenite (MOR) zeolites increased with increasing Si/Al molar ratio, which was achieved by dealumination. The amount of hydrogen adsorption increased linearly with increasing pore volume of the zeolites. The hydrogen adsorption behavior was found to be dependent mainly on the pore volume of the zeolites. © 2010 Elsevier Ltd. All rights reserved.

Bang Y.,Chonnam National University | Bang Y.,Asia Pacific Center for Theoretical Physics
Physical Review Letters | Year: 2010

We studied the field dependencies of specific heat coefficient γ(H)=limT→0C(T,H)/T and thermal conductivity coefficient limT→0κ(T,H)/T of the ±s-wave state in the mixed state. It is a generic feature of the two band s-wave state with the unequal sizes of gaps, small ΔS and large ΔL, that Doppler shift of the quasiparticle excitations (Volovik effect) creates a finite density of states, on the extended states outside of vortex cores, proportional to H in contrast to the √H dependence of the d-wave state. The impurity scattering effect makes this generic H-linear dependence sublinear approaching to the √H behavior. Our calculations of limT→0κ(T,H)/T successfully fit the experimental data of Ba(Fe1-xCox)2 As2 with different Co-doping x by systematically varying the gap size ratio R=|ΔS|/|ΔL|. We also resolve the dilemma of a substantial value of γ(H→0) but almost zero value of limT→0κ(T,H→0)/T. © 2010 The American Physical Society.

Lee D.H.,Chonnam National University
Journal of Craniofacial Surgery | Year: 2016

ABSTRACT: Primary mucosal malignant melanoma of the nasal cavity is a rare disease. The authors present the patient of a pedunculated primary mucosal malignant melanoma originated from the posterior nasal septum, which was successfully removed via the endoscopic approach. Clinicians should consider the possibility that a primary mucosal malignant melanoma may originate in the nasal cavity, mimicking the other more frequently observed lesions. © 2016 by Mutaz B. Habal, MD.

Park A.,Chonnam National University | Lee S.,Chonnam National University
Organic Letters | Year: 2012

Palladium-catalyzed carbonylation of aryl iodides and trimethylsilylacetonitrile to produce benzoylacetonitrile derivatives through a one-pot, three-component reaction is described. This preparation method provides good yields of the carbonylated products without any additional ligands. It has a broad substrate scope with a high tolerance for a variety of functional groups. © 2012 American Chemical Society.

Kim K.H.,Chonnam National University | Lee H.S.,Chonnam National University | Kim S.H.,Chonnam National University | Kim J.N.,Chonnam National University
Tetrahedron Letters | Year: 2012

A palladium-catalyzed oxidative arylation of chromones was examined. A regioselective 2-arylation of chromone was carried out via a double C-H activation process. The procedure provided an expedient approach for the preparation of flavone derivatives. © 2012 Elsevier Ltd. All rights reserved.

Cuong H.B.,Chonnam National University | Lee B.-T.,Chonnam National University
Applied Surface Science | Year: 2015

Effects of oxygen partial pressure within the Ar process plasma on the optical, structural, and electrical properties of magnetron-sputtered ZnMgBeO films were investigated in detail. It was observed that the optical energy bandgap (Eg) values of the ZnMgBeO films substantially decrease with the oxygen addition, from 5.3 to 4.3 eV as the oxygen partial pressure increases from zero to one. The full-width-at-half-maximum (FWHM) values of the (0 0 0 2) XRD peaks drastically decrease with the addition of a small amount of oxygen but then increase with further oxygen addition. All the films had very high sheet resistance, 1.3-1.4 GΩ/□. It was also observed that the concentration of Zn within the films significantly increased with the oxygen addition, which was proposed to be mainly responsible for the observed decrease in Eg. It was also proposed that the FWHM change due to the oxygen addition may be attributable to three factors, film composition, grain size, and point defect density, as confirmed by results of TEM and XPS investigations. © 2015 Elsevier B.V. All rights reserved.

Lee J.S.,Chonnam National University | Unithrattil S.,Chonnam National University | Im W.B.,Chonnam National University
Journal of Alloys and Compounds | Year: 2013

The possibility of using a solid solution as a light convertor in white LEDs was studied. A solid solution of Sr3AlO4F and Sr 3SiO5 was prepared by solid-state reaction and was activated with Ce3+. Phosphor exhibits an asymmetric yellow-orange emission band which is broadened and red-shifted when coactivated with Tb 3+. Decay profile analysis using the Inokuti-Hirayama model revealed that the mechanism involved was electric dipole-quadrupole interaction. The critical distance was calculated from concentration quenching data, multipolar interaction, and exchange interaction. The thermal stability of photoluminescence was investigated by assuming an Arrhenius temperature dependence, and the activation energy for thermal quenching was calculated. When analyzed in combination with an InGaN LED, the phosphor exhibited high color-rendering index and excellent correlated color temperature. These results demonstrate that this solid solution phosphor with its superior properties is highly suitable for use in white LEDs. © 2012 Elsevier B.V. All rights reserved.

Jang B.-O.,Chonnam National University | Park S.-H.,Chonnam National University | Lee W.-J.,Chonnam National University
Journal of Alloys and Compounds | Year: 2013

Co-Sn alloy embedded carbon nanofiber (Co-Sn/CNF) composites functioning as anode materials were prepared by using electrospinning technique followed with stabilization and carbonization with heat treatments. Co-Sn/CNF carbonized at 800 °C (Co-Sn/CNF-800) was composed of large amounts of CoSn alloy compared to CoSn2 alloy and Sn crystalline phases both embedded in carbon nanofibers (CNF). The 80th discharge capacity of Co-Sn/CNFs were ranked by their preparation temperature: 800 °C (560 mA h g1) > 900 °C (504 mA h g1) > 700 °C (501 mA h g1). The excellent specific discharge capacity and cycle retention of the sample prepared at 800 °C were attributed to the abundant formation of CoSn facilitating the reversible reaction, the presence of Sn, the buffering role of CNF, and the excellent distribution of nanoparticles by electrospinning. The electrochemical performance for Co-Sn/CNF-900 is lower than that of Co-Sn/CNF-800 because of the formation of CoSn2 showing a two-step mechanism involving irreversible reaction. © 2013 Elsevier B.V. All rights reserved.

Joo S.-P.,Chonnam National University
Journal of Craniofacial Surgery | Year: 2016

ABSTRACT: Enophthalmos after a ventriculo-peritoneal (V-P) shunt placement is very rare. Previous defects of the orbital wall with intracranial hypotension can cause enophthalmos after V-P shunting. The authors present 2 patients of enophthalmos with orbital wall defects resulting from anterior clinoidectomy that was performed during previous aneurysmal surgery. Both patients received a V-P shunt for hydrocephalus after subarachnoid hemorrhage. Although the hydrocephalus was improved by V-P shunts in both patients, sunken eyes were observed. The patients received reconstructive surgery of the superior orbital wall using titanium mesh and recovered after surgery without any neurological deficits. Here, the authors present 2 patients of enophthalmos with orbital wall defects treated by orbital wall reconstruction.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0, where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially. © 2016 by Mutaz B. Habal, MD.

Lim J.W.,Chonnam National University | Kim K.H.,Chonnam National University | Kim S.H.,Chonnam National University | Kim J.N.,Chonnam National University
Tetrahedron Letters | Year: 2012

An expedient synthetic approach of naphthalenes was developed by the reaction of Morita-Baylis-Hillman bromides and arylacetylenes. The synthesis was carried out via a tandem copper-catalyzed alkynylation, propargyl-allenyl isomerization, and 6π-electrocyclization protocol. © 2012 Elsevier Ltd. All rights reserved.

Byeon Y.,Chonnam National University | Lee H.Y.,Chonnam National University | Lee K.,Chonnam National University | Back K.,Chonnam National University
Journal of Pineal Research | Year: 2014

Ectopic overexpression of melatonin biosynthetic genes of animal origin has been used to generate melatonin-rich transgenic plants to examine the functional roles of melatonin in plants. However, the subcellular localization of these proteins expressed in the transgenic plants remains unknown. We studied the localization of sheep (Ovis aries) serotonin N-acetyltransferase (OaSNAT) and a translational fusion of a rice SNAT transit peptide to OaSNAT (TS:OaSNAT) in plants. Laser confocal microscopy analysis revealed that both OaSNAT and TS:OaSNAT proteins were localized to the cytoplasm even with the addition of the transit sequence to OaSNAT. Transgenic rice plants overexpressing the TS:OaSNAT fusion transgene exhibited high SNAT enzyme activity relative to untransformed wild-type plants, but lower activity than transgenic rice plants expressing the wild-type OaSNAT gene. Melatonin levels in both types of transgenic rice plant corresponded well with SNAT enzyme activity levels. The TS:OaSNAT transgenic lines exhibited increased seminal root growth relative to wild-type plants, but less than in the OaSNAT transgenic lines, confirming that melatonin promotes root growth. Seed-specific OaSNAT expression under the control of a rice prolamin promoter did not confer high levels of melatonin production in transgenic rice seeds compared with seeds from transgenic plants expressing OaSNAT under the control of the constitutive maize ubiquitin promoter. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Huh J.W.,Chonnam National University | Kim H.R.,Chonnam National University
Journal of Laparoendoscopic and Advanced Surgical Techniques | Year: 2012

Background: The role of laparoscopic resection in patients with clinical T4 colorectal cancer remains controversial. This study compared the outcome of laparoscopic resection for clinical T4 colorectal cancer with that of an open approach. Subjects and Methods: Forty-three consecutive patients undergoing surgery for colorectal cancer with suspected involvement of another organ (T4) by computed tomography and/or magnetic resonance imaging were reviewed. Twenty-four patients who underwent laparoscopic colorectal resection were matched with 19 patients who underwent an open approach. All available clinicopathologic variables possibly associated with the outcome were compared. Results: Two patients (8.3%) who underwent the laparoscopic procedure were converted to the open technique. Patients in the open group displayed more advanced pathologic T category (P=.008) and underwent more combined operation than patients in the laparoscopic group (P=.017). The R0 resection rate was 75% in the laparoscopic group and 52.6% in the open group (P=.135). Patients in the laparoscopic group displayed a tendency for lower estimated blood loss (P=.083), sooner bowel movement (P=.075), and shorter length of hospital stay (P=.089) than patients in the open group. No significant differences in postoperative complications were observed between the laparoscopic and open groups (20.8% versus 36.8%, P=.246). After a median follow-up of 27 months, the 3-year disease-free survival rate in the laparoscopic group was found to be not significantly different from that in the open group (76.7% versus 58.8%; P=.303). Conclusions: Laparoscopic colorectal resection for T4 colorectal cancer is feasible and has perioperative and short-term oncologic outcomes similar to those of an open approach. However, further studies with long-term follow-up are needed to resolve these issues. © Copyright 2012, Mary Ann Liebert, Inc.

Jeong S.-H.,Korea Basic Science Institute | Park J.-H.,Chonnam National University | Lee B.-T.,Chonnam National University
Journal of Alloys and Compounds | Year: 2014

The transparent and conductive Mg-Al co-doped ZnMgAlO films with different Mg contents have been sputter grown on quartz substrates at room temperature. Modulation of the band-gap and conductivity was tried by varying the Mg doping rate from 5 at.% to 20 at.% at a fixed Al content of 2 at.%. Optical characterization of the deposited ZnMgAlO films confirmed that the average optical transmittance in the visible region was ∼85% and the transparency of the near infra-red (NIR) region expanded to further IR region with increasing the Mg doping level, which can be profitable for the application where higher NIR transmittance is required. At a low Mg doping level of 5 at.%, the best quality of electrical properties were achieved with the resistivity of 3.7 × 10-4 Ω cm, the electron concentration of 7 × 1020/cm3, and the Hall mobility of 25.66 cm2/V s, whereas with further Mg doping up to 20 at.%, the resistivity increased to 1.9 × 10-2 Ω cm, which is accompanied with a degradation of crystal quality. Optical band-gap reached to 3.87 eV at a high Mg doping level of 20 at.%. Additional phonon modes at 275 cm-1 and 648 cm -1 found in the Raman spectra of the ZnMgAlO films were assigned to the host lattice defect vibrational complexes related with Al dopants and it was suggested that the broadening, weakening, and shift of phonon peaks with increasing the Mg doping level may be related with the enhanced lattice distortion in ZnO crystal and the reduced mass change induced by substitution of Mg in Zn sites. © 2014 Elsevier B.V. All rights reserved.

Back K.,Chonnam National University | Park S.,Chonnam National University
Journal of Pineal Research | Year: 2012

The effect of melatonin on root growth after germination was examined in transgenic rice seedlings expressing sheep serotonin N-acetyltransferase (NAT). Enhanced melatonin levels were found in T3 homozygous seedlings because of the ectopic overexpression of sheep NAT, which is believed to be the rate-limiting enzyme in melatonin biosynthesis in animals. Compared with wild-type rice seeds, the transgenic rice seeds showed enhanced seminal root growth and an analogous number of adventitious roots 4 and 10 days after seeding on half-strength Murashige and Skoog medium. The enhanced initial seminal root growth in the transgenic seedlings matched their increased root biomass well. We also found that treatment with 0.5 and 1 μm melatonin promoted seminal root growth of the wild type under continuous light. These results indicate that melatonin plays an important role in regulating both seminal root length and root growth after germination in monocotyledonous rice plants. This is the first report on the effects of melatonin on root growth in gain-of-function mutant plants that produce high levels of melatonin. © 2012 John Wiley & Sons A/S.

Lee H.W.,Chonnam National University
Journal of the Korean Wood Science and Technology | Year: 2014

RPS (Renewable Portfolio Standard) has increased wood pellet demand dramatically in recent years in Korea where self-supply rate of wood pellet is not more than 10%. However global production capacity of wood pellet is prospected to be unable to meet the global demand after 2020. Therefore it is urgently needed to develop new sustainable biomass energy resources which can replace wood pellet at lower cost. As a result of this study EFB (empty fruit bunch) and MF (mesocarp fiber), the representative solid palm biomass, are estimated to be generated at the rate of 20 and 28 million tons per year (based on 10% moisture content) in Malaysia and Indonesia, respectively in 2012. Total annual generation rate of EFB and MF is estimated as 48 million tons per year only in Malaysia and Indonesia in 2012. With calorific value of over 90% of wood pellet EFB is expected to be a excellent biomass energy resource which can replace wood pellet. EFB can be utilized as fuel for power generation or industrial purpose. However EFB may not be a proper fuel for domestic and greenhouse heating because of its high ash content.

Seo D.W.,Chonnam National University | Lee J.Y.,Chonnam National University
Expert Systems with Applications | Year: 2013

A new physical query interface is proposed for tangible augmented tagging and interaction using two types of context-aware AR interfaces, visual and invisible interfaces. In visual interfaces, augmented reality markers are utilized for supporting intuitive interactions and manipulations with digital contents. RFID is used as an invisible interface for supporting line-of-sight, direct and query interactions. By combining the advantages of visual and invisible interfaces, more natural interaction with digital contents can be provided, which can remove the difficulty of using typical AR paddles, cubes and gadgets that are widely used in AR interactions. Semantic ontology is adopted in order to effectively support physical querying, filtering and grouping through the combination of multiple RFID tags. The proposed approach has been applied to a variety of multi-media interactions, such as digital product review and digital catalog or book interaction. We show the effectiveness and the advantages of the proposed approach by demonstrating several implementation results and by a usability study. © 2012 Elsevier Ltd. All rights reserved.

Seo D.W.,KISTI | Lee J.Y.,Chonnam National University
Expert Systems with Applications | Year: 2013

Several studies have been carried out on augmented reality (AR)-based environments that deal with user interfaces for manipulating and interacting with virtual objects aimed at improving immersive feeling and natural interaction. Most of these studies have utilized AR paddles or AR cubes for interactions. However, these interactions overly constrain the users in their ability to directly manipulate AR objects and are limited in providing natural feeling in the user interface. This paper presents a novel approach to natural and intuitive interactions through a direct hand touchable interface in various AR-based user experiences. It combines markerless augmented reality with a depth camera to effectively detect multiple hand touches in an AR space. Furthermore, to simplify hand touch recognition, the point cloud generated by Kinect is analyzed and filtered out. The proposed approach can easily trigger AR interactions, and allows users to experience more intuitive and natural sensations and provides much control efficiency in diverse AR environments. Furthermore, it can easily solve the occlusion problem of the hand and arm region inherent in conventional AR approaches through the analysis of the extracted point cloud. We present the effectiveness and advantages of the proposed approach by demonstrating several implementation results such as interactive AR car design and touchable AR pamphlet. We also present an analysis of a usability study to compare the proposed approach with other well-known AR interactions. © 2012 Elsevier Ltd. All rights reserved.

Jang W.S.,Chonnam National University
International braz j urol : official journal of the Brazilian Society of Urology | Year: 2013

Endoscopic urethrotomy is an alternative method in treatment of urethral stricture. However, it have high recurrence rate because of the remained fibrotic tissue. Removal of the fibrotic tissue can maintain the patency of the urethral lumen after the procedure. We report the therapeutic efficacy of our initial experience using pediatric resectoscope for treating anterior urethral stricture in 16 cases. From January 2009 to April 2011, transurethral resection with pediatric resectoscope was primarily performed on 16 patients with anterior urethral stricture. Retrograde urethrography, uroflowmetry, postvoid residual volume, IPSS score and QoL score were performed preoperatively. We used 11.5Fr pediatric resectoscope (Wolf) and monopolar electrosurgical generator. The stricture was incised under vision at the 12 o'clock location or the site of maximum scar tissue or narrowing in asymmetric strictures for working space. After incision, transurethral resection with pediatric resectoscope was performed to all scar tissues. Monopolar cutting current was set on 45 watt and coagulation current was set on 30 watt, fulgurate mode. Postoperatively, drainage of the bladder was performed for 7 days using an 18F latex catheter. Patients were followed up by IPSS score, QoL score, uroflowmetry and postvoid residual volume. Successful results without recurrence were achieved in 11 of 16 patients. Postoperative urethral dilation had been performed average 2.4 times (0~6 times). When we classified the results by etiology, the number of successful results in strictures with a trauma, iatrogenic, or unknown cause was 5 (7/11), 3 (3/4) and 1 (1/1), respectively. In 5 patients who failed treatment, we repeated transurethral resection with pediatric resectoscope in 1 patient, and periodic urethral dilation in 4 patients. No operative complications occurred in any patients. Transurethral resection with pediatric resectoscope is an effective therapeutic method for anterior urethral stricture. More long-term follow-up and large scale studies are needed to confirm the efficacy of this procedure.

Yun S.P.,Chonnam National University | Ryu J.M.,Chonnam National University | Han H.J.,Chonnam National University
Journal of Cellular Physiology | Year: 2011

Although glucocorticoids strongly affect numerous biological processes including cell growth, development, and homeostasis, their effects on migration of human mesenchymal stem cells (hMSCs) are unclear. Therefore, we investigated the role of dexamethasone (DEX) and its related signaling pathways on migration of hMSCs. We found that DEX, at 10-8 to 10-6 M, significantly increased migration after a 24 h incubation, and DEX (10-6 M) increased migration at >12 h. Moreover, DEX (10-6 M) increased the level of glucocorticoid receptor (GR)-α mRNA and protein expression, but not GR-β mRNA. The increases in DEX-induced migration were inhibited by the GR antagonist mifepristone (10-7 M). In addition, DEX increased integrin-linked kinase (ILK) and α-parvin expression but did not change PINCH-1/2 expression in lysate. DEX also increased formations of complex with ILK and α-parvin, and ILK and PINCH-1/2 as shown by immunoprecipitation, which were all inhibited by mifepristone. DEX-induced migration was blocked by ILK and α-parvin small interfering(si)RNAs. In addition, DEX increased focal adhesion kinase (FAK) and paxillin expression, which were attenuated by ILK and α-parvin siRNAs. DEX-induced cell migration was inhibited by FAK/paxillin siRNAs. DEX also increased β1-integrin expression, which was blocked by FAK/paxillin siRNAs. In addition, DEX-induced cell migration was inhibited by β1-integrin siRNA. Downregulation of ILK, α-parvin, FAK/paxillin and β1-integrin expression by siRNAs decreased DEX-induced filamentous(F)-actin organization and migration of hMSCs. In conclusion, DEX partially stimulates hMSC migration by the expression of β1-integrin through formation of a PINCH-1/2/ILK/α-parvin complex (PIP complex), and FAK and paxillin expression. © 2010 Wiley-Liss, Inc.

Wang Y.-X.,Chonnam National University | Kim Y.-B.,Chonnam National University
IEEE/ASME Transactions on Mechatronics | Year: 2014

This paper studies the modeling and air flow control for a proton exchange membrane (PEM) fuel cells using model predictive control (MPC). The PEM fuel cell model was constructed using cell current-voltage relationships, including Nernst voltage, activation, ohmic, and concentration voltage loss. A thermal model was also included for PEM fuel cell model to represent the pressure characteristics. The validity of the model was evaluated by determining the model parameters, and its accuracy was verified against the experimental data. To prevent starvation that might occur in the fuel cell hybrid vehicle system, air flow control was utilized using MPC. MATLAB/Simulink model was first constructed to simulate the efficacy of MPC using the linearized model. The validity and performance superiority of the model were then confirmed by comparing them with the proportional-integral control result. To apply the MPC in real-time, a LabVIEW-based experimental rig was constructed, and its efficacy in preventing air starvation was verified. © 1996-2012 IEEE.

Nguyen Q.P.B.,Chonnam National University | Kim T.H.,Chonnam National University
Tetrahedron | Year: 2013

A facile and rapid method for the parallel synthesis of a series of secondary and tertiary amines by the direct reductive amination of aldehydes and ketones with Hantzsch ester under solvent- and catalyst-free has been developed. The scope and limitation of this method are described. © 2013 Elsevier Ltd. All rights reserved.

Ahn S.-J.,Chonnam National University | Nam S.-R.,Myongji University | Choi J.-H.,Chonnam National University | Moon S.-I.,Seoul National University
IEEE Transactions on Smart Grid | Year: 2013

This paper is concerned with the power dispatch problem of distributed generators (DGs) for optimal operation of a microgrid. The objective is to minimize the fuel cost during the grid-connected operation, while ensuring stable operation after islanding. To achieve this goal, the economic dispatch (ED) problem and related constraints are formulated. The constraints considered in this study are: i) reserve for variation in load demand, ii) reserve for variation in the power outputs of non-dispatchable DGs, iii) flow limits between two adjacent areas, and iv) reserve for the stable islanded operation. The first three constraints, which have been employed in ED problem for conventional power systems, are modified to apply to Microgrids. We also provide a detailed formulation of the constraint for stable islanded operation in accordance with two power-sharing principles: i) fixed droop and ii) adjustable droop. The problem is solved using a modified direct search method, and the effect of the constraints on the operational cost is investigated via numerical simulations. © 2012 IEEE.

Song I.-K.,KEPCO E&C | Jung W.-W.,KEPCO E&C | Kim J.-Y.,KEPCO E&C | Yun S.-Y.,KEPCO E&C | And 2 more authors.
IEEE Transactions on Smart Grid | Year: 2013

The integration of Distributed Energy Resources (DERs) into the future Smart Distribution Network (SDN) has challenging issues regarding the successful development of smart grids. The SDN offers new opportunities in the improvement of the efficiency of power distribution networks. The DERs will be distributed in the existing distribution networks, interconnected in customer areas and operated on its own schedule without communication to the control center of the existing distribution system. The DER units have both positive and negative effects regarding SDN operations. With the appropriate operation of the DER units in the SDN, losses can be reduced during normal operations and they can support local loads during abnormal conditions. Thus, the positive effects of the DER units need to be enabled in the SDN by adopting advanced operation schemes. In this paper, the smart control functions for the DER units in the SDN are defined and classified. In addition, the integration schemes for the SDN with DER units are introduced. The proposed operation strategies will be implemented into the Korean Smart Distribution Management System (KSDMS) as operation schemes used for loss reduction and service restoration. A sample case study shows the effectiveness of the proposed operation schemes to achieve smart operation functions for the SDN with DER units. © 2013 IEEE.

Kang S.J.,Chonnam National University | Joung Y.H.,Chonnam National University
Journal of Materials Science: Materials in Electronics | Year: 2013

The 3 wt% Al-doped zinc oxide (AZO) thin films were fabricated on quartz substrates at a fixed oxygen pressure of 200 mTorr with various substrate temperatures (room temp. ∼500 C) by using pulsed laser deposition in order to investigate the microstructure, optical, and electrical properties of AZO thin films. All thin films were shown to be c-axis oriented, exhibiting only a (002) diffraction peak. The AZO thin film, fabricated at 200 mTorr and 400 C, showed the highest (002) orientation and the full width at half maximum (FWHM) of the (002) diffraction peak was 0.42. The c-axis lattice constant decreased with increasing substrate temperature. The electrical property indicated that the highest carrier concentration (1.27 × 1021 cm-3) and the lowest resistivity (6.72 × 10-4 Ωcm) were obtained in the AZO thin film fabricated at 200 mTorr and 400 C. The optical transmittance in the visible region was higher than 80 %. The Burstein-Moss effect, which shifts to a high photon energy, was observed. © 2012 Springer Science+Business Media New York.

Shewale P.S.,Shivaji University | Patil V.B.,University of Solapur | Shin S.W.,Chonnam National University | Kim J.H.,Chonnam National University | Uplane M.D.,Shivaji University
Sensors and Actuators, B: Chemical | Year: 2013

The ZnO-based thin films doped with 1-4 wt% Cu were deposited on the glass substrates using the advanced spray pyrolysis technique. All films are deposited at 473 K. The crystallinity and morphology of the films were characterized by XRD, TEM and FE-SEM respectively. The structural analyses of the films indicate that they are polycrystalline and have a hexagonal wurtzite structure; however Cu doping enhances the preferential orientation along the [0 0 2]. The energy dispersive X-ray spectroscopic analysis (EDX) confirmed an enhancement in the amount of Cu in the film with increase in the copper concentration in the starting solution. The sensor response was estimated by the change in the electrical conductance of the film in the absence and presence of H2S gas. The sensor response and selectivity in relation to, operation temperature, Cu doping concentration and the gas concentration has been systematically studied. A significant response (∼0.38) towards 20 ppm H2S at 523 K operating temperature is observed for the 4 wt% Cu-doped ZnO. The Pd-sensitized 4 wt% Cu doped ZnO film exhibits improved sensing characteristics with good stability. © 2013 Elsevier B.V.

Park H.K.,Chonnam National University | Heo J.,Chonnam National University
Applied Surface Science | Year: 2014

The improved efficiency of aluminum doping in ZnO (AZO) thin films grown by atomic layer deposition was demonstrated by controlling the number of surface reaction sites for trimethylalumium (TMA). Prolonged purge time (120 s) for deionized water used as an oxidant decreased the number of hydroxyl groups on the surface via dehydration reaction, resulting in the reduced chemisorption of TMA. The enhanced doping efficiency by sparse distribution of Al dopants was demonstrated by the increased carrier concentration from ∼4 × 10 20 to ∼6 × 1020 cm-3 for the same Al doping cycle ratio. A comparison was made among the AZO films formed by using the control and modified recipes, focusing on their electrical, structural, and optical properties. © 2014 Elsevier B.V.

Kim B.-H.,Chonnam National University | Eun J.-B.,Chonnam National University
Korean Journal of Food Science and Technology | Year: 2012

The optimum conditions for manufacturing pomegranate makgeolli, cloudy Korean rice wine, treated with different levels of pomegranate (Punica granatum L.) juice concentrate were investigated. The pH, titratable acidity, amino acid content, soluble solid content, and alcohol content were measured, and the sensory properties of the makgeolli were evaluated. The pH, titratable acidity, soluble solid content and alcohol content of pomegranate makgeolli increased as the addition level of pomegranate juice concentrate increased. The amino acid content of makgeolli significantly decreased with increasing addition level of pomegranate juice concentrate. In the sensory evaluation, makgeolli with 3% pomegranate juice concentrate added during one-step-brewing had the most preferable flavor, sweetness, bitterness and overall acceptance among all samples. In conclusion, the addition of 3% pomegranate juice concentrate during one-step-brewing for makgeolli would be the best conditions for manufacturing pomegranate makgeolli. © The Korean Society of Food Science and Technology.

Park J.S.,Chonnam National University | Park J.H.,Chonnam National University | Khoi P.N.,Chonnam National University | Joo Y.E.,Chonnam National University | Jung Y.D.,Chonnam National University
Carcinogenesis | Year: 2011

Overexpression of recepteur d'Origine nantais (RON) and urokinase plasminogen activator receptor (uPAR) have been observed in human gastric cancers. However, the interaction between RON and uPAR in gastric cancer is unclear. The present study investigated the effect of macrophage-stimulating protein (MSP, the RON ligand) on uPAR expression and the underlying signal pathways in human gastric cancer AGS cells. uPAR messenger RNA expression was induced by MSP in a time-and concentration-dependent manner. MSP also induced uPAR promoter activity. The introduction of RON-specific small interfering RNA (siRNA) significantly affected the MSP-induced uPAR transcription. Deleted and site-directed mutagenesis studies demonstrated the involvement of the binding sites of transcription factor nuclear factor-kappaB (NF-κB) and activator protein (AP)-1 in the MSP-induced uPAR expression. Studies with expression vectors encoding mutatedtype NF-κB signaling molecules and AP-1 decoy confirmed that NF-κB and AP-1 were essential for the MSP-induced uPAR expression. In addition, MSP induced the activation of extracellular signal-regulated kinase-1/2 (Erk-1/2), c-Jun amino terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK). Dominant-negative mutants (K97M and TAM67) and specific inhibitors of Erk-1/2 and JNK were able to suppress the MSPinduced uPAR expression. AGS cells pretreated with MSP showed a remarkably enhanced invasiveness, which was partially abrogated by siRNA-targeted RON and uPAR-neutralizing antibodies. The above results suggest that MSP induces uPAR expression via MAPK, AP-1 and NF-κB signaling pathways and, in turn, stimulates cell invasiveness in human gastric cancer AGS cells. © The Author 2010. Published by Oxford University Press. All rights reserved.

Lee S.H.,Chonnam National University | Lee Y.J.,Chonnam National University | Han H.J.,Chonnam National University
Journal of Cellular Physiology | Year: 2011

Cell migration is largely dependent on integrin (IN) binding to the extracellular matrix, and several signaling pathways involved in these processes have been shown to be modified by hypoxia. Therefore, the aim of this study was to determine the influence of hypoxia on fibronectin (FN) and IN β1 expression in mouse embryonic stem cells (mESCs) and their signaling pathways to modulate proliferation. FN and IN β1 expression were significantly increased in hypoxic mESCs by 24 h. Hypoxia also increased cell attachment, which was accompanied by concomitant increases in the binding level of FN and IN β1. Hypoxia-induced FN expression was mediated by increased phosphatidylinositol 3 kinase (PI3K)/Akt and mammalian target of rapamycin (mTOR) phosphorylation, and hypoxia-inducible factor-1α (HIF-1α) expression. Moreover, under hypoxic conditions, focal adhesion kinase (FAK) and Src phosphorylation were increased in a time-dependent fashion; these increases were blocked by IN β1 antibody. In addition, the hypoxia induced increase of F-actin distribution and cell migration (activation of matrix metalloproteinase-2 and -9) was inhibited by IN β1 antibody. Indeed, hypoxia increased the level of cell-cycle regulatory protein and DNA synthesis. In conclusion, hypoxia increases the proliferation and migration of mESCs via FN-IN β1 production through the PI3K/Akt, mTOR, and HIF-1α pathways, followed by FAK activation. © 2010 Wiley-Liss, Inc.

Chang H.-S.,Chonnam National University | Kim J.-W.,Gangneung - Wonju National University
Operative Dentistry | Year: 2014

The purpose of this study was to investigate whether dentin-layer thickness of resin overlays could affect the early hardness and shear bond strength of dual-cure resin cement (DCRC, RelyX ARC) after light curing with light curing units (LCUs) of various power densities: Optilux 360 (360), Elipar Freelight 2 (FL2), and Elipar S10 (S10). Resin overlays were fabricated using an indirect composite resin (Sinfony) with a dentin layer, an enamel layer, and a translucent layer of 0.5 mm thickness each (0.5-0.5-0.5) or of 0.2 mm, 0.5 mm, and 0.8 mm thickness (0.2-0.5-0.8), respectively. The DCRC was light cured for 40 seconds through the overlays, and surface hardness and shear bond strength to bovine dentin were tested 10 minutes after the start of light curing. Surface hardness was higher when the DCRC was light cured through the 0.2-0.5-0.8 combination than when the DCRC was light cured through the 0.5-0.5-0.5 combination with all LCUs. The ratio of upper surface hardness of DCRC light cured through resin overlays relative to the upper surface hardness of DCRC light cured directly was more than 90% only when the DCRC was light cured with S10 through the 0.2-0.5-0.8 combination. The shear bond strength value was higher when the DCRC was light cured with S10 through the 0.2-0.5-0.8 combination than when light cured with S10 through the 0.5-0.5-0.5 combination. This study indicates that reducing the dentin-layer thickness while increasing the translucent-layer thickness of resin inlays can increase the photopolymerization of DCRC, thereby increasing the early bond strength of resin inlays to dentin. ©Operative Dentistry, 2014.

Ham D.-H.,Chonnam National University
Cognition, Technology and Work | Year: 2015

This study is aimed at developing a new method for modelling work domain knowledge with the combined use of abstraction hierarchy (AH) and living systems theory (LST). AH has been widely used as a work domain knowledge representation framework in the field of cognitive systems engineering and human–computer interaction, and its usefulness has been proved in a range of work domains. However, its effective use still remains a challenging issue. In order to address this problem, this study firstly points out several issues that can be raised in the use of AH and then explains why and how LST can give concepts and principles helpful to resolve them. The proposed method offers a framework for how to combine AH and LST, particularly to identify functional knowledge at higher abstraction levels. It also offers a process for modelling the knowledge of a work domain based on the combined use of AH and LST. The use of the proposed method is exemplified by modelling the knowledge of a simplified secondary cooling system of nuclear power plants. The proposed method is a new approach to refining the concepts of AH and modelling the knowledge of a work domain that humans should interact. It is believed that it will be a useful tool for knowledge modellers in identifying and modelling the knowledge of a work domain in terms of its functional structure. However, it should be noted that its usefulness can be limited to technology-oriented engineering systems; it would not be easily applied to human activity-oriented systems. © 2015, Springer-Verlag London.

Some genetic studies indicate that plant homologues of proteins involved in chromatin modification and remodeling in other organisms may regulate plant development. Previously, we described an Arabidopsis mutant with altered cold-responsive gene expression (acg1) displaying a late flowering phenotype, a null allele of fve. FVE is a homologue of the mammalian retinoblastoma- associated protein (RbAp), one component of a histone deacetylase (HDAC) complex involved in transcriptional repression, and has been shown to be involved in the deacetylation of the FLOWERING LOCUS C (FLC) chromatin encoding for a repressor of flowering. In an effort to gain insight into the biochemical functions of FVE, we overexpressed FVE tagged with the hemagglutinin (HA) and FLAG epitope at the N-terminus in acg1 mutants. The results of physiological and molecular analyses demonstrated that FVE overexpression in acg1 rescued the mutant phenotypes, including late flowering and alterations in floral pathway gene expression such as FLC, SUPPRESSOR OF OVEREXPRESSION OF CO1 (SOC1), and FLOWERING LOCUS T (FT), and also super-induced cold-responsive reporter gene expression. The chromatin immunoprecipitation experiments revealed the amplification of specific DNA regions of FLC and COLD-REGULATED 15A (COR15A), indicating that FVE may bind to the FLC and COR15A chromatin. Gel-filtration chromatography and the immunoprecipitation of putative FVE complexes showed that FVE forms a protein complex of approximately 1.0 MDa. These results demonstrate that FVE may exist as a multiprotein complex, similar to the mammalian HDAC complex harboring RbAp, to regulate flowering time and cold response by associating with the FLC and COR chromatin. © 2011 KSMCB.

Hong G.P.,Chonnam National University | Min S.-G.,Konkuk University | Chin K.B.,Chonnam National University
Meat Science | Year: 2012

In this study, the effects of microbial transglutaminase (MTG) and calcium alginate (CA) systems in combination with soybean oil on the emulsion properties of porcine myofibrillar protein (MP) were evaluated under various pH conditions. MTG was shown to improve emulsifying capacity and creaming stability, which increased with increasing pH values up to 6.5. The CA did not influence emulsifying capacity, but it improved the creaming stability of the MP-stabilized emulsions. Both MTG and CA enhanced the rheological properties, but their effects on the physical characteristics of the protein evidenced an opposite trend in relation to pH, i.e., the MTG system improved both the emulsion and gelling properties with increasing pH, whereas the CA system was effective when the pH was lowered. By combining the two MP gelling systems, a stable and pH-insensible emulsion could be produced. © 2011 Elsevier Ltd.

Lee J.,Chonnam National University | Lim K.-T.,Chonnam National University
Journal of Cellular Biochemistry | Year: 2011

Styrax japonica Siebold et al Zuccarini (SJSZ) has been used to heal inflammation and bronchitis as folk medicine in Korea. Firstly, glycoprotein isolated from SJSZ (SJSZ glycoprotein) has a molecular weight with 38 kDa and consists of carbohydrate (57.64%) and protein (42.35%). In the composition of SJSZ glycoprotein, carbohydrate mostly consists of glucose (28.17%), galactose (21.85%), and mannose (2.62%) out of 52.64%, respectively. The protein consists of Trp (W, 7.01%), Pro (P, 6.72%), and Ile (I, 5.42%) out of 42.35% as three major amino acids, while total amount of other amino acids is 23.20%. The purpose of this study is to know whether the SJSZ glycoprotein (38 kDa) induces the cell cycle arrest and apoptosis in HepG2 cells. Cytotoxicity was evaluated using MTT and lactate dehydrogenase assay and amount of intracellular reactive oxygen species (iROS) and nitric oxide (NO) was measured using fluorescence microplate reader. Activities of cell cycle-related proteins [p53, p21, p27, Cyclin D1, and cyclin-dependent kinase (CDK)4] and apoptosis-related factors [iNOS, Bid, Bcl-2/bax, cytochrome c, caspase-9, caspase-3, and poly-(ADP-ribose) polymerase (PARP)] were assessed by Western blot and fluorescence-activated cell sorter (FACS) analysis. In the cell cycle-related proteins, SJSZ glycoprotein (50 μg/ml) significantly enhances the expression of p53, p21, and p27, whereas it suppressed the activity of cyclin D1/CDK4. In the apoptosis-related factors, SJSZ glycoprotein (50 μg/ml) stimulates to increase iROS, and NO, to activate iNOS, Bid, Bcl-2/bax, cytochrome c, caspase-9, caspase-3, and PARP. SJSZ glycoprotein (50 μg/ml) has potent effect to arrest cell cycle from G 0/G 1 to S and to induce apoptosis in HepG2 cells. © 2011 Wiley Periodicals, Inc.

Wang Y.-X.,Chonnam National University | Yu D.-H.,Chonnam National University | Kim Y.-B.,Chonnam National University
IEEE Transactions on Industrial Electronics | Year: 2014

This paper studies a robust control for regulating a boost converter capacitor output voltage. The boost converter is inherently a highly nonlinear system that displays interconnected state variables and system parameter variations due to load change with input disturbances. Therefore, a robust control scheme is required to cope with these characteristics. The main objective of controlling the capacitor output voltage is to keep the output voltage constant under input voltage variations with fast response, and little overshoot and ripples. To satisfy this objective, a robust control with time-delay concept is introduced. The control utilizes time-delayed switching input to the converter, as well as output current and voltage variables, to replace the unknown dynamics and disturbance. To prove the effectiveness of the algorithm, two operating point variations are considered: variations in source voltage, and changes in output load. Simulations are performed using MATLAB/Simulink to show the effectiveness of the algorithm by choosing the output voltage lift, drop, settling time, and ripples as the system performance criteria. Then, a comparison of the results is made of the proportional and integral control, and the sliding mode control. An experimental test is also performed to demonstrate the effectiveness of the system. © 1982-2012 IEEE.

Wu X.,Chonnam National University | Parmar M.,Chonnam National University | Lee D.-W.,Chonnam National University
IEEE/ASME Transactions on Mechatronics | Year: 2014

In this paper, we introduce a novel seesaw-structured energy harvester for tire-pressure monitoring system (TPMS) applications. The unique design of the proposed energy harvester can effectively avoid the influence of enormous centrifugal force, which is attributed to the balance characteristic of seesaw structure. Two magnets placed on the seesaw end could swing the seesaw structure in every rotating cycle with the help of external noncontact magnetic repulsive force, and subsequently this unbalanced seesaw structure impacts the polyvinylidene difluoride (PVDF) cantilevers to generate the power. A miniature energy harvester prototype is fabricated using a 3-D printing technique. In the performance testing experiment, a peak voltage of 4.6 V and a constant peak output power of 36 μW with the optimized load resistance value of 0.6 MΩ are achieved within a superwide rotating frequency range of 215-965 r/min (25.7-115.4 km/h for a real car). Moreover, an average power per second is 5.625 μW at 750 r/min, which could be potential power supply for the TPMS application. © 1996-2012 IEEE.

Sun J.,Chonnam National University | Jeon J.-H.,Korea Advanced Institute of Science and Technology | Shin M.,Chonnam National University | Shin H.-C.,Korea Advanced Institute of Science and Technology | And 2 more authors.
Acta Crystallographica Section D: Biological Crystallography | Year: 2014

A multi-subunit ribonucleoprotein complex termed the Cmr RNA-silencing complex recognizes and destroys viral RNA in the CRISPR-mediated immune defence mechanism in many prokaryotes using an as yet unclear mechanism. In Archaeo-globus fulgidus, this complex consists of six subunits, Cmr1-Cmr6. Here, the crystal structure of Cmr1 from A. fulgidus is reported, revealing that the protein is composed of two tightly associated ferredoxin-like domains. The domain located at the N-terminus is structurally most similar to the N-terminal ferredoxin-like domain of the CRISPR RNA-processing enzyme Cas6 from Pyrococcus furiosus. An ensuing mutational analysis identified a highly conserved basic surface patch that binds single-stranded nucleic acids specifically, including the mature CRISPR RNA, but in a sequence-independent manner. In addition, this subunit was found to cleave single-stranded RNA. Together, these studies elucidate the structure and the catalytic activity of the Cmr1 subunit. © 2014 International Union of Crystallography.

Hong Y.J.,Chonnam National University | Jeong M.H.,Chonnam National University | Ahn Y.,Chonnam National University | Kang J.C.,Chonnam National University
International Journal of Cardiology | Year: 2013

There are controversies about the use of drug-eluting stent (DES) in patients with acute myocardial infarction (AMI). Recent trials of DES in patients with AMI have shown the relative safety of DES. However, some physicians hesitate to use DES in AMI patients because of increased risk of stent thrombosis and death. We summarized in this article about the efficacy and safety of DES in AMI patients who were enrolled in Korea Acute Myocardial Infarction Registry (KAMIR). © 2012 Elsevier Ireland Ltd. All rights reserved.

Lee H.J.,Chonnam National University | Kim K.H.,Chonnam National University | Kim S.H.,Chonnam National University | Kim J.N.,Chonnam National University
Tetrahedron Letters | Year: 2013

A palladium-catalyzed oxidative arylation of 3-(monosubstituted)alkylidene- oxindoles with arenes afforded 3-(disubstituted)alkylidene-oxindoles in good to moderate yields. © 2012 Elsevier Ltd. All rights reserved.

Lim C.H.,Chonnam National University | Kim S.H.,Chonnam National University | Kim K.H.,Chonnam National University | Kim J.N.,Chonnam National University
Tetrahedron Letters | Year: 2013

An efficient synthetic method of o-terphenyls was developed from Morita-Baylis-Hillman adducts. The synthesis was carried out via a sequential bromination of MBH adducts, Wittig reaction with various aldehydes, 6π-electrocyclization, and a base-mediated aerobic oxidation process. © 2013 Elsevier Ltd. All rights reserved.

Kim S.H.,Chonnam National University | Lim C.H.,Chonnam National University | Kim J.N.,Chonnam National University
Tetrahedron Letters | Year: 2013

An efficient synthesis of 5-phosphorylated uracil derivatives has been carried out via an oxidative cross-coupling reaction between uracil derivatives and dialkyl phosphites in the presence of Mn(OAc)3 in AcOH. © 2012 Elsevier Ltd. All rights reserved.

Darvishi M.T.,Razi University | Hessari P.,Chonnam National University
Computers and Mathematics with Applications | Year: 2011

In this paper, we establish a modified symmetric successive overrelaxation (MSSOR) method, to solve augmented systems of linear equations, which uses two relaxation parameters. This method is an extension of the symmetric SOR (SSOR) iterative method. The convergence of the MSSOR method for augmented systems is studied. Numerical examples show that the new method is an efficient method. © 2011 Elsevier Ltd. All rights reserved.

Aravindan V.,Nanyang Technological University | Lee Y.-S.,Chonnam National University | Madhavi S.,Nanyang Technological University
Advanced Energy Materials | Year: 2015

Research activities related to the development of negative electrodes for construction of high-performance Li-ion batteries (LIBs) with conventional cathodes such as LiCoO2, LiFePO4, and LiMn2O4 are described. The anode materials are classified in to three main categories, insertion, conversion, and alloying type, based on their reactivity with Li. Although numerous materials have been proposed (i.e., for half-cell assembly), few of them have reached commercial applications, apart from graphite, Li4Ti5O12, Si, and Sn-Co-C. This clearly demonstrates that full-cell studies are desperately needed rather than just characterizing materials in half-cell assemblies. Additionally, the performance of such anodes in practical Li-ion configurations (full-cell) is much more important than merely proposing materials for LIBs. Irreversible capacity loss, huge volume variation, unstable solid electrolyte interface layer formation, and poor cycleability are the main issues for conversion and alloy type anodes. This review addresses how best to circumvent the mentioned issues during the construction of Li-ion cells and the future prospects of such anodes are described in detail. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Aravindan V.,Nanyang Technological University | Lee Y.-S.,Chonnam National University | Yazami R.,Nanyang Technological University | Madhavi S.,Nanyang Technological University
Materials Today | Year: 2015

This review describes the overall research activities focused on developing high-performance Li-ion batteries (LIBs) fabricated with various TiO2 polymorphs as insertion anodes. Although several polymorphs of TiO2 have been reported, only the anatase, rutile, bronze, and brookite phases have proven promising. The bronze phase's lower insertion potential, high reversibility and high current performance makes it an attractive candidate for constructing high power and high energy density Li-ion power packs. In addition, the bronze phase exhibits superior performance over the conventional, commercialized spinel Li4Ti5O12 anodes when coupled with the olivine phase LiFePO4. This exceptional behavior of the bronze phase opens new avenues for the development of high power LIBs capable of powering zero emission transportation and grid storage. © 2015 The Authors.

Lee S.B.,Chonnam National University | Suh M.C.,Chonnam National University
Plant Cell Reports | Year: 2015

The aerial parts of plants are covered with a cuticle, a hydrophobic layer consisting of cutin polyester and cuticular waxes that protects them from various environmental stresses. Cuticular waxes mainly comprise very long chain fatty acids and their derivatives such as aldehydes, alkanes, secondary alcohols, ketones, primary alcohols, and wax esters that are also important raw materials for the production of lubricants, adhesives, cosmetics, and biofuels. The major function of cuticular waxes is to control non-stomatal water loss and gas exchange. In recent years, the in planta roles of many genes involved in cuticular wax biosynthesis have been characterized not only from model organisms like Arabidopsis thaliana and saltwater cress (Eutrema salsugineum), but also crop plants including maize, rice, wheat, tomato, petunia, Medicago sativa, Medicago truncatula, rapeseed, and Camelina sativa through genetic, biochemical, molecular, genomic, and cell biological approaches. In this review, we discuss recent advances in the understanding of the biological functions of genes involved in cuticular wax biosynthesis, transport, and regulation of wax deposition from Arabidopsis and crop species, provide information on cuticular wax amounts and composition in various organs of nine representative plant species, and suggest the important issues that need to be investigated in this field of study. © 2015, Springer-Verlag Berlin Heidelberg.

Wang W.L.,Chonnam National University | Nguyen V.H.,Chonnam National University | Gu H.-B.,Chonnam National University
Applied Surface Science | Year: 2014

Electrochemical characteristics of CoO anode are highly dependent on the use of binders. Its electrochemical reversibility is drastically improved by using poly(acrylic acid) (PAA) as a binder in comparison with the commonly used poly(vinylidene fluoride) (PVdF) binder. PAA can effectively buffer the volume expansion of the CoO electrode during the lithium insertion and extraction, resulting in improving electrochemical characteristics of the electrode. The cyclic stability of CoO electrode with PAA binder is remarkably improved. Impedance of CoO electrode with PAA binder is much smaller than that of PVdF binder. Moreover, the reversible capacity reaches 860 mA h g-1 at a current density of 50 mA g-1. © 2013 Elsevier B.V. All rights reserved.

Chang N.K.,Chonnam National University
Korean journal of radiology : official journal of the Korean Radiological Society | Year: 2012

To evaluate the effectiveness of ultrasound-guided radiofrequency (RF) ablation in patients with incompletely treated hepatocellular carcinoma (HCC) after transcatheter arterial chemoembolization (TACE) and to evaluate possible prognostic factors for this therapy. Thirty nine patients with incompletely treated single HCC (≤ 5 cm) after TACE were treated with RF ablation. All patients were evaluated for complete tumor ablation rate, local recurrence-free rate, overall survival rate, and complications. Local recurrence-free rate and overall survival rate were calculated using the Kaplan-Meier method. The possible prognostic factors of local recurrence-free rate and survival rate were analyzed using Cox proportional-hazards regression model. The complete tumor ablation rate was 92.3%. Local recurrence-free rates for 1-, 2-, 3-, and 5-years were 81.7%, 63.1%, 53.6%, and 35.7%, respectively. One-, 2-, 3-, and 5-year overall survival rates were 96.9%, 82.9%, 67.8%, and 48.4%, respectively. Among prognostic factors included in the analysis, only tumor diameter (≤ 2 cm versus > 2 cm) was statistically significant in terms of predicting local recurrence. Complications were observed in two patients, one with liver abscess and the other with portal venous thrombosis. Ultrasound-guided RF ablation could be effective and safe in treating incompletely treated HCC after TACE. The diameter of HCC was a significant prognostic factor for local recurrence.

Kim J.W.,Chonnam National University
Korean journal of radiology : official journal of the Korean Radiological Society | Year: 2012

The purpose of this study was to prospectively compare pre-operative computed tomography (CT) perfusion parameters with tumor grade from colorectal adenocarcinoma (CRC) and to correlate pre-operative CT perfusion parameters with microvessel density (MVD) to evaluate angiogenesis in CRC. Pre-operative perfusion CTs were performed with a 64-channel multidetector row CT in 27 patients (17 women and 10 men; age range 32-82 years) who were diagnosed with CRC involving the sigmoid and rectum between August 2006 and November 2007. All patients underwent surgery without pre-operative chemotherapy or radiation therapy. Dynamic perfusion CTs were performed for 65 seconds after intravenous injection of contrast medium (100 mL, 300 mg of iodine per mL, 5 mL/sec). Before surgery, blood flow (BF), blood volume, mean transit time (MTT), and permeability-surface area product were measured in the tumor. After surgery, one gastrointestinal pathologist evaluated tumor grade and performed immunohistochemical staining using CD 34 to determine MVD in each tumor. The Kruskal-Wallis test was used to compare CT perfusion parameters with tumor grade, and Pearson's correlation analysis was used to correlate CT perfusion parameters with MVD. In 27 patients with CRC, tumor grading was as follows: well differentiated (n = 8); moderately differentiated (n = 15); and poorly differentiated (n = 4). BF was higher in moderately differentiated CRC than well differentiated and poorly differentiated CRCs (p = 0.14). MTT was shorter in moderately differentiated than well differentiated and poorly differentiated CRCs (p = 0.039). The MVD was greater in poorly differentiated than well differentiated and moderately differentiated CRCs (p = 0.034). There was no significant correlation between other perfusion parameters and tumor grade. There was no significant correlation between CT perfusion parameters and MVD. BF and MTT measurement by perfusion CT is effective in predicting moderately differentiated CRCs. However, perfusion CT is limited in distinguishing well differentiated and poorly differentiated CRCs. Pre-operative perfusion CT does not reflect the MVD of CRCs.

Hong S.-H.,Inha University | Jang M.-S.,Inha University | Cho S.J.,Chonnam National University | Ahn W.-S.,Inha University
Chemical Communications | Year: 2014

Mesoporous chabazite ion-exchanged with Ca2+ was effective for CO2 capture at 20 bar and 473 K, whereas 13X as a support material enabled recyclable carbonation of ca. 8 wt% Mg(OH)2 approaching the theoretical maximum for CO2 capture with 10% H2O. © 2014 the Partner Organisations.

Kim S.H.,Chonnam National University | Kim K.H.,Chonnam National University | Kim J.N.,Chonnam National University
Advanced Synthesis and Catalysis | Year: 2011

A practical and efficient synthesis of various 1,2,5-tricarbonyl compounds is described. The synthesis has been carried out by a conjugate addition of methyl cyanoacetate to the β-position of α,β-unsaturated carbonyl compounds and a subsequent copper(I) iodide-catalyzed aerobic oxidation. In addition, various α-aryl- and α-alkyl-α-keto esters have been synthesized using a similar approach. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kim J.,Electronics and Telecommunications Research Institute | Hwang B.,Chonnam National University
Information Sciences | Year: 2016

We face an increasing need to discover knowledge from data streams in real-time. Real-time stream data mining needs a compact data structure to store transactions in the recent sliding-window by one scan, and an efficient algorithm to discover frequent itemsets from the compact data structure. In this paper, we propose a novel data mining algorithm, called CanTree-GTree, which discovers the complete frequent itemsets from real-time transactions based on sliding-windows. The algorithm uses two data structures: CanTree and GTree. CanTree compactly represents all transactions in a sliding-window by one scan, and serves as a base-tree. The algorithm efficiently maintains the base-tree by adding new transactions and removing old transactions without any reconstruction phases. A novel data structure, called GTree (Group Tree), serves as a projection-tree for each data item. The algorithm traverses each node of the base-tree only once by using a top-down tree traversal method to build the projection-tree, and discovers frequent itemsets by low processing cost. The proposed algorithm is therefore effective for discovering frequent itemsets in real-time stream data. Our performance evaluation experiments with other algorithms based on CPSTree and CanTree-FPTree show that our algorithm outperforms the other algorithms in the synthetic data set by about 35% and 26% of run-time cost, respectively. Also, we confirm that the proposed algorithm shows excellent results on real-world data sets. © 2016 Elsevier Inc.

Thomas R.,Chonnam National University | Park I.-K.,Chonnam National University | Jeong Y.Y.,Chonnam National University
International Journal of Molecular Sciences | Year: 2013

Superparamagnetic iron oxide nanoparticles (SPION) have emerged as an MRI contrast agent for tumor imaging due to their efficacy and safety. Their utility has been proven in clinical applications with a series of marketed SPION-based contrast agents. Extensive research has been performed to study various strategies that could improve SPION by tailoring the surface chemistry and by applying additional therapeutic functionality. Research into the dual-modal contrast uses of SPION has developed because these applications can save time and effort by reducing the number of imaging sessions. In addition to multimodal strategies, efforts have been made to develop multifunctional nanoparticles that carry both diagnostic and therapeutic cargos specifically for cancer. This review provides an overview of recent advances in multimodality imaging agents and focuses on iron oxide based nanoparticles and their theranostic applications for cancer. Furthermore, we discuss the physiochemical properties and compare different synthesis methods of SPION for the development of multimodal contrast agents. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

Lee J.S.,Seoul National University | Kwon O.S.,Seoul National University | Park S.J.,Seoul National University | Park E.Y.,Seoul National University | And 3 more authors.
ACS Nano | Year: 2011

Ultrafine metal-oxide-decorated hybrid carbon nanofibers (CNFs) were fabricated by a single-nozzle co-electrospinning process using a phase-separated mixed polymer composite solution and heat treatment. To decorate metal oxides on the CNF surface, core (PAN) and shell (PVP) structured nanofibers (NFs) were fabricated as starting materials. The core-shell NF structure was prepared by single-nozzle co-electrospinning because of the incompatibility of the two polymers. Ultrafine hybrid CNFs were then formed by decomposing the PVP phase, converting the metal precursors to metal oxide nanonodules, and transforming the PAN to CNFs of ca. 40 nm diameter during heat treatment. The decoration morphology of the metal oxide nanonodules could be controlled by precursor concentration in the PVP solution. These ultrafine hybrid CNFs were applied to a dimethyl methylphosphonate (DMMP) chemical sensor at room temperature with excellent sensitivity. The minimum detectable level (MDL) of hybrid CNFs was as low as 0.1 ppb, which is 10-100 times higher than for a chemical sensor based on carbon nanotubes. This is because the metal oxide nanonodules of hybrid CNFs increase the surface area and affinity to DMMP vapor. Our new synthetic methodology promises to be an effective approach to fabricating hybrid CNF/inorganic nanostructures for future sensing technologies. © 2011 American Chemical Society.

Kim K.H.,Chonnam National University | Lim C.H.,Chonnam National University | Lim J.W.,Chonnam National University | Kim J.N.,Chonnam National University
Advanced Synthesis and Catalysis | Year: 2014

An efficient intramolecular arene-alkene oxidative coupling of 1,4-diaryl-1,3-butadienes has been developed involving the use of a 2,3-dichloro-5,6-dicyano-para-benzoquinone (DDQ)/acid catalyst. The reaction involves the generation of a radical cation by abstraction of an electron from the substrate with DDQ, an intramolecular Friedel-Crafts-type reaction, and the loss of hydrogen radical. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Jeong S.,Ulsan National Institute of Science and Technology | Kim D.,Ulsan National Institute of Science and Technology | Shin S.,Ulsan National Institute of Science and Technology | Moon D.,Pohang Accelerator Laboratory | And 2 more authors.
Chemistry of Materials | Year: 2014

Isoreticular and polymorphic 3-D MOFs were prepared via the combination of direct solvothermal reactions, postsynthetic ligand exchanges of the MOFs prepared via the direct solvothermal reactions, and postsynthetic ligand insertions into a 2-D MOF. The appropriate pore dimensions, surface areas, and adsorption enthalpies of the MOFs combined well to produce the largest working CO2 capture capacities via the pressure swing adsorption process. © 2014 American Chemical Society.

Kim C.H.,Chonnam National University | Kim B.-H.,Daegu University
Journal of Electroanalytical Chemistry | Year: 2014

Zinc oxide (ZnO)-based porous carbon composite nanofibers (ZnO-CCNFs) are prepared by one-step electrospinning and subsequent thermal treatment using zinc acetate, as the pore generator and ZnO precursor. In particular, the PAN-based nanofiber paper contains in-frame incorporated nitrogen surface functionalities, due to its large residual nitrogen content in the char. The N functionalities doped at the graphite edges enhances their capacitance by the pseudocapacitive effect. Therefore, the ZnO-CCNFs showed higher capacitance (163 F g-1 at 1 mA cm-2) and energy density (20.80-14.80 W h kg-1 in the power density range of 400-20,000 W kg-1) than the control sample of carbon nanofibers (CNFs) in aqueous electrolyte. The combination of the high surface area of CNFs with the large capacity of surface functional groups such as N, O, and ZnO as the faradic electrode material affords the advantages of both the double layer capacitance and the pseudocapacitance, thereby offering potential applications for supercapacitors. © 2014 Elsevier B.V. All rights reserved.

Irudayanathan F.M.,Chonnam National University | Noh J.,Chonnam National University | Choi J.,Chonnam National University | Lee S.,Chonnam National University
Advanced Synthesis and Catalysis | Year: 2014

Isoindolin-1-ones and isoquinolin-1-ones were selectively synthesized from the reaction of 2-halobenzoic acid, arylalkynylcarboxylic acid and ammonium acetate (NH4OAc) in the presence of cesium carbonate (Cs2CO3) and a copper catalyst. Conducting the reaction under one-pot conditions provided isoindolin-1-ones in good yields. Changing the addition sequence of ammonium acetate after all reagents had reacted at 120 °C for 6 h selectively produced isoquinolin-1-ones. A variety of arylalkynylcarboxylic acids produced the corresponding isoindolin-1-ones and isoquinolin-1-ones in good yields. © 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kim S.Y.,Chonnam National University | Yang K.,Chonnam National University | Kim B.-H.,Daegu University
Electrochimica Acta | Year: 2014

Heteroatom-decorated nanoporous carbon nanofiber composites (Si-CNFCs) containing grapheneare prepared through one-step electrospinning with the help of tetraethylorthosilicate (TEOS) and a subsequent thermal treatment, and their electrochemical properties as supercapacitor electrodes are investigated. The introduction of TEOS and graphene into the polyacrylonitrile (PAN) solution induced superior material properties, such as a high surface area, stabilized Si-related structures, and increased electrical conductivity, resulting in the enhancement of the electrochemical performances of electrodes. The supercapacitor electrode prepared with 3wt% graphene and 10 wt% TEOS shows high specific capacitance, 144.79 Fg-1, and high energy density, 16.82-8.33 Whkg-1, at power densities ranging from 400-20,000 Wkg-1 in a 6 M KOH aqueous solution. Therefore, the Si-CNFC electrodes promote desirable interactions and improve the accessibility of the ions solvated with a polar solvent, yielding a high charge capacity and improving the energy/power capabilities through the electrical double-layer and pseudo-capacitive effects. © 2014 Elsevier Ltd.

Jang Y.-S.,Chonnam National University | Byun H.-S.,Chonnam National University
Journal of Chemical and Engineering Data | Year: 2014

High pressure cloud-point data were reported for poly(2-butoxyethyl acrylate) [P(2-BEA)] in propane (C3H8), propylene (C 3H6), butane (C4H10), 1-butene (C4H8), and dimethyl ether (DME) (CH3OCH 3), as well as for the P(2-BEA) + 2-butoxyethyl acrylate (2-BEA) (or DME) system in supercritical CO2. Cloud-point pressures for the P(2-BEA) + C3 hydrocarbons curves were ca. 22 MPa higher than those for P(2-BEA) + C4 hydrocarbons, at a constant temperature of ca. 393 K. The cloud-point pressure for the P(2-BEA) + DME system was located between C3 and C4 hydrocarbons at pressures below ca. 20.0 MPa. The P(2-BEA) + CO2 + 0.649 and 0.680 2-BEA phase behavior curves intersect a one phase (fluid) → two phases (liquid + vapor) curve at temperatures of 353.6 K (at 24.5 MPa) and 413.4 K (at 32.3 MPa). The location of the P(2-BEA) + CO2 cloud-point curve shifts to lower temperatures and pressures upon the addition of 2-BEA or DME. Vapor-liquid phase equilibrium data at high pressures were presented for the CO2 + 2-BEA system at temperatures ranging from (313.2 to 393.2) K and pressures up to 20.38 MPa. The CO2 + 2-BEA system exhibits type-I phase behavior with a continuous critical mixture curve and was adequately modeled using the Peng-Robinson equation of state. © 2014 American Chemical Society.

Yoon S.-D.,Chonnam National University | Kim C.-R.,Chonnam National University | Byun H.-S.,Chonnam National University
Fluid Phase Equilibria | Year: 2014

Pressure-composition isotherms of phase equilibria for the CO2+isoalkyl acetate systems are investigated in the static method at five temperatures of (313.2, 333.2, 353.2, 373.2 and 393.2)K and pressures up to 18.24MPa. The CO2+isobutyl acetate, CO2+isopentyl acetate and CO2+isooctyl acetate systems have continuous critical mixture (locus) curves that exhibit maximums in pressure-temperature space between the critical temperatures of CO2 and isoalkyl acetate (isobutyl acetate, isopentyl acetate and isooctyl acetate). The solubility of isobutyl acetate, isopentyl acetate and isooctyl acetate for the CO2+isobutyl acetate, CO2+isopentyl acetate and CO2+isooctyl acetate systems increases as the temperature increases at constant pressure. The CO2+isobutyl acetate, CO2+isopentyl acetate and CO2+isooctyl acetate systems exhibit type-I phase behavior. The experimental results for the CO2+isobutyl acetate, CO2+isopentyl acetate and CO2+isooctyl acetate systems are correlated with Peng-Robinson equation of state using a mixing rule including two adjustable parameters. © 2014 Elsevier B.V.

Kim B.-H.,Daegu University | Yang K.S.,Chonnam National University
Journal of Electroanalytical Chemistry | Year: 2014

Porous carbon nanofibers with SiOC/SiOSi group (Si/ACNF) mats are produced by incorporating tetraethyl orthosilicate (TEOS) into polyacrylonitrile (PAN) via electrospinning/activation, and their electrochemical properties as a supercapacitor electrode are investigated. The Si/ACNF exhibits a high surface area of up to 1386.91 m2 g-1 as result of the ultramicropore size distributions centered at approximately 0.8 nm and mesopore volume fraction up to 38%. The gravimetric capacitance of the Si/ACNF webs in an organic electrolyte is 91.95 F g-1, and the energy densities are 59.72-88.23 Wh kg-1 over the power density range of 1000-20,000 W kg-1. The electrochemical capacitance of a Si/ACNF electrode is closely related to the pore size distribution, surface area, and ionic accessibility of the electrode material, providing a large charge capacity and high rate capability. © 2013 Elsevier B.V. All rights reserved.

Yuvaraj S.,Bharathiar University | Amaresh S.,Chonnam National University | Lee Y.S.,Chonnam National University | Selvan R.K.,Bharathiar University
RSC Advances | Year: 2014

Co2SnO4 particles were synthesized by a sonochemical method under different pH conditions, followed by carbon coating by a hydrothermal method. The thermal stability and compound formation temperature were identified through thermogravimetric analysis (TGA). The X-ray diffraction (XRD) pattern elucidated the compound formation of Co2SnO4 with cubic structure. Co2SnO4 encapsulated with carbon was confirmed through the TEM and HRTEM analysis and the approximate thickness of carbon was around 20 nm. The pristine-Co2SnO4 and carbon coated Co2SnO4 provided a discharge capacity of 777 mA h g-1 and 780 mA h g-1 at the current density of 40 mA g-1 with the capacity retention of 67% and 81% respectively in the 20th cycle. The charge transfer resistance of carbon coated Co 2SnO4 was low when compared to pristine Co 2SnO4 which lead to good reversibility of the material. The electrochemical study revealed the excellent electrochemical performance of the carbon coated Co2SnO4 particles with superior cycling stability and electronic conductivity. © 2014 The Royal Society of Chemistry.

Kim C.H.,Chonnam National University | Kim B.-H.,Daegu University
Electrochimica Acta | Year: 2014

Organic-inorganic hybrid composite carbon nanofibers (CCNFs) are prepared by one-step electrospinning and subsequent thermal treatment using polyphenylsilane (PPS) as an inorganic precursor. We investigate the structural properties and electrochemical behavior of these CCNF materials when applied as supercapacitor electrodes as a function of the carbonization temperature ranging from 800 to 1000°C. The introduction of PPS induces thermal stability for the organic-inorganic hybrid CCNFs via the incorporation of a porous structure with stabilized functional structures such as silicon oxynitride (SiO xNy) and silicon oxycarbide (SiOxC y). This phenomenon is attributed to the synergistic effect of both the double-layer capacitance and the pseudo-capacitive effect induced by the porous carbon layer and the some surface functionalities), thereby providing high charge capacity, power and energy density. © 2013 Elsevier Ltd. All rights reserved.

Avunje S.,Chonnam National University | Oh M.-J.,Chonnam National University | Jung S.-J.,Chonnam National University
Fish and Shellfish Immunology | Year: 2013

The olive flounder (Paralichthys olivaceus) is susceptible to viral haemorrhagic septicaemia virus (VHSV) at 15 °C but no mortality is observed at 20 °C even though the virus can grow profusely in vitro. Thus, we designed an experiment to better understand the immune response of olive flounder to VHSV when the host reared at 15 °C or 20 °C and infected with the virus. Olive flounder (18-22 g) reared at 15 ± 0.5 °C or 20 ± 0.5 °C were intra-peritoneally injected with VHSV (107.8 TCID50/fish) and sampled (n = 5) for head kidney at 3, 6, 12 hpi, 1, 2, 4 and 7 dpi; similarly, mock injected control groups (n = 5). Real-time PCR-based absolute quantification method was followed to quantify copies of VHSV gRNA and mRNA, while the immune gene expression of the olive flounder was quantified relative to internal control, β-actin. Viral infection resulted in a cumulative mortality of 24% in olive flounder reared at 15 °C, but no mortality was recorded in the 20 °C group or control groups. TLR2 and TLR7 expression at 15 °C was enhanced during early-infection phase (3-6 hpi) and recovery phase (4-7 dpi) when viral transcription was low, but expression was significantly reduced (12 hpi-1 dpi) at peak-infection period. However, the 20 °C group showed low viral transcription and expressed high level of TLR7 and a moderately higher unchanged level of TLR2. In both the groups, TLR3 expression was unaffected. Nevertheless, expression of MDA5 and LGP2 increased significantly irrespective of rearing temperature at the time of peak infection, hence at 15 °C VHSV down-regulated expression of TLR2 and TLR7 but not MDA5 or LGP2. Comparatively, at 15 °C IRF3 expressed high but IRF7 remained very low. Interleukins (IL-1β, IL-6 and IL-8) were significantly elevated in both the groups, but quicker and for a shorter period at 20 °C. In the 15 °C group, an extended period of expression of ILs could create an unsafe prolonged inflammatory condition. The olive flounders expressed high ISGs at 15 °C but were lagging by 12 h than 20 °C group. Based on these findings, we concluded that viral-mediated disruption of TLR2 and TLR7 expression in the 15 °C group could have delayed the host interferon response and provided a window for high viral growth. However, an effective host immune response at 20 °C contained VHSV from reaching the critical limit. © 2013 Elsevier Ltd.

Jung H.-R.,Chonnam National University | Lee W.-J.,Chonnam National University
Journal of Electroanalytical Chemistry | Year: 2011

SnOx-embedded carbon nanofibers (SnOx/CNF) were synthesized by electrospinning a composite solution of Sn(II) acetate, polyacrylonitrile (PAN), and polyvinylpyrrolidone (PVP) in N,N-dimethylformamide (DMF), followed by stabilization and carbonization. The SnOx for SnOx/CNF-700 was distributed about below 2 nm in diameter, whereas that for SnOx/CNF-800 represented around below 4 nm. The fine structure of SnOx for SnOx/CNF was confirmed by analysis of extended X-ray absorption fine structure (EXAFS). The diameter of the fibers decreased with increasing temperature, whereas both SnOx particles and electrical conductivity of SnOx/CNF increased. Both SnO x/CNF-700 and SnOx/CNF-800 were prepared as disordered structures, whereas SnOx/CNF-900 was synthesized as an SnO 2-like structure. The disordered transformation inducing excellent electrochemical performance originated form CNF prepared by electrospinning and proper heat treatment. Pure SnO2 displayed low electrochemical performance, indicating a typical large volume change and high mechanical stress. On the contrary, SnOx/CNF-800 represented outstanding specific discharge capacity and exceptional cycle retention at the same time, representing a coulomb efficiency of 71% even in the initial cycle. The specific discharge capacity for SnOx/CNF-800 slightly decreased by the 20th cycle, and then gradually increased by the 100th cycle. The CNF plays an important role as a buffering agent to prevent SnOx particles from agglomerating. The CNF having 1D pathway with high electrical conductivity leads to the promotion of charge transfer as well as mass transfer. © 2011 Elsevier B.V. All rights reserved.

Lee H.W.,Chonnam National University | Kim J.,Chonnam National University
Plant and Cell Physiology | Year: 2013

Expansins are non-hydrolytic cell wall-loosening proteins involved in a variety of plant developmental processes during which cell wall modification occurs. Cell wall remodeling proteins including expansins have been suggested to be involved in cell separation to facilitate the emergence of lateral roots (LRs) through the overlaying tissues of the primary root. LBD18/ASL20 activates EXPANSINA14 (EXPA14) expression by directly binding to the EXPA14 promoter to enhance LR emergence in Arabidopsis thaliana. Here we show that EXPA17 is another target gene regulated by LBD18 to promote LR formation in Arabidopsis. We showed that nuclear translocation of the LBD18:GR fusion protein expressed under the Cauliflower mosaic virus (CaMV) 35S promoter or under the LBD18 promoter by dexamethasone treatment results in an increase in EXPA17 transcript levels. β-Glucuronidase (GUS) expression under the EXPA17 promoter, which is detected only in the roots of the wild type, was reduced in the LR primordium and overlaying tissues in an lbd18 mutant background. The number of emerged LRs of the EXPA17 RNAi (RNA interference) Arabidopsis lines was significantly lower than that of the wild type. Overexpression of EXPA17 in Arabidopsis increased the density of emerged LRs in the presence of auxin compared with the wild type. LR induction experiments with a gravitropic stimulus showed that LR emergence is delayed in the EXPA17 RNAi plants compared with the wild type. In addition, EXPA4 expression was also detected in overlaying tissues of the LR primordium and was inducible by LBD18. Taken together, these results support the notion that LBD18 up-regulates a subset of EXP genes to enhance cell separation to promote LR emergence in Arabidopsis. © 2013 The Author.

Lee W.-J.,University of Dundee | Wilkinson C.M.,University of Dundee | Hwang H.-S.,Chonnam National University
Journal of Forensic Sciences | Year: 2012

The utilization of 3D computerized systems has allowed more effective procedures for forensic facial reconstruction. Three 3D computerized facial reconstructions were produced using skull models from live adult Korean subjects to assess facial morphology prediction accuracy. The 3D skeletal and facial data were recorded from the subjects in an upright position using a cone-beam CT scanner. Shell-to-shell deviation maps were created using 3D surface comparison software, and the deviation errors between the reconstructed and target faces were measured. Results showed that 54%, 65%, and 77% of the three facial reconstruction surfaces had <2.5mm of error when compared to the relevant target face. The average error for each reconstruction was -0.46mm (SD=2.81) for A, -0.31mm (SD=2.40) for B, and -0.49mm (SD=2.16) for C. The facial features of the reconstructions demonstrated good levels of accuracy compared to the target faces. © 2011 American Academy of Forensic Sciences.

Wu X.,Chonnam National University | Lee D.W.,Chonnam National University
Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) | Year: 2015

In this paper, a high-efficient piezoelectric energy harvester based on non-contact coupling technique is proposed and characterized, which allows it, for the first time, to take advantage of multi-cantilevers and frequency up-conversion technique to enhance the power generation efficiency for ambient excitation. The unique energy harvester can effectively scavenge environmental vibration energy with a wide bandwidth. Aiming for high space efficiency and less installation constrains, folded cantilevers are designed for this energy harvester. With a load resistance of 50 kω, a maximum output power of 18.45 μW is achieved with the fabricated energy harvester, which is a suitable power supply for the sensor nodes in WSN applications. © 2015 IEEE.

Koh Y.-I.,Chonnam National University | Shim J.-U.,Chonnam National University
International Archives of Allergy and Immunology | Year: 2010

Background: Natural killer T (NKT) cells play an essential role in the development of airway hyperresponsiveness (AHR) in murine asthma. However, their role in the pathogenesis of human asthma has not been defined. The present study investigated whether NKT cells were associated with AHR or airway inflammation in human asthma. Methods: We measured the number of NKT cells in peripheral blood and induced sputum obtained from 61 asthmatics, 10 patients with eosinophilic bronchitis (EB) and 17 controls. EB was used as a disease control model to investigate the mechanisms of AHR in asthma outside the influence of eosinophilic airway inflammation. The quantities of CD3+CD56+ NKT cells, 6B11+ NKT cells and Vα24+ NKT cells were measured by flow cytometry. Results: The measurement of NKT cells did not differ among the 3 groups in peripheral blood. However, in sputum, CD3+CD56+ NKT cells and Vα24+ NKT cells were significantly increased in patients with asthma and EB compared to controls, and 6B11+ NKT cells were also increased in patients with asthma and EB, although not significantly. There was no difference in the measurements of sputum NKT cells between asthmatics and patients with EB. Sputum Vα24+ NKT cells were inversely associated with the degree of AHR in asthmatics. Conclusions: Sputum NKT cells might play an important role in the pathogenesis of eosinophilic airway inflammation in human chronic stable asthma. However, functional studies on airway NKT cells are needed to elucidate the association between NKT cells and AHR. © 2010 S. Karger AG, Basel.

Choi H.J.,Chonnam National University
International Journal of Naval Architecture and Ocean Engineering | Year: 2015

In the present study, a hydrodynamic hull-form optimization algorithm for a container ship was presented in terms of the minimum wave-making resistance. Bell-shaped modification functions were developed to modify the original hull-form and a sequential quadratic programming algorithm was used as an optimizer. The wave-making re-sistance as an objective function was obtained by the Rankine source panel method in which non-linear free surface conditions and the trim and sinkage of the ship were fully taken into account. Numerical computation was performed to investigate the validity and effectiveness of the proposed hull-form modification algorithm for the container carrier. The computational results were validated by comparing them with the experimental data. © 2015, Int. J. Nav. Archit. Ocean Eng. All rights reserved.

Sung M.S.,Chonnam National University | Kang Y.S.,Chonnam National University | Heo H.,Chonnam National University | Park S.W.,Chonnam National University
Ophthalmology | Year: 2016

Purpose To investigate the characteristics of optic disc rotation and ocular parameters affecting optic disc rotation in healthy myopic eyes. Design Cross-sectional, comparative study. Participants A total of 220 participants with healthy myopic eyes. Methods Spherical equivalent (SE) refractive error, axial length, central corneal thickness, and intraocular pressure (IOP) were evaluated. Optic disc tilt ratio, degree of optic disc rotation, and area of β-zone parapapillary atrophy (PPA) were measured. Optic nerve head (ONH) parameters and thickness of the peripapillary retinal nerve fiber layer (pRNFL) and macular ganglion cell-inner plexiform layer (mGCIPL) were measured using Cirrus optical coherence tomography (Carl Zeiss Meditec Inc., Dublin, CA). Subjects were divided into 2 groups, group 1 with superior rotation and group 2 with inferior rotation of the optic disc, and various parameters were compared. Linear regression analysis was performed to evaluate the relationships between the degree of optic disc rotation and several parameters. Main Outcome Measures Degree of optic disc rotation. Results Among 220 eyes, 147 showed superior rotation of the optic disc and 73 showed inferior rotation. The mean tilt ratio and rotation degree were 1.16 and -19.51°, respectively, in group 1 and 1.20 and 28.93°, respectively, in group 2, showing significant differences between the groups (P = 0.028 and P = 0.035, respectively). There were also significant between-group differences in IOP (15.59 vs. 16.34 mmHg), SE refractive error (-4.05 vs. -5.66 diopters [D]), axial length (25.51 vs. 26.26 mm), and area of β-zone PPA (0.32 vs. 0.70 mm2). Overall, a multivariate linear regression analysis showed that IOP, axial length, and area of β-zone PPA were significant parameters related to the degree of optic disc rotation (P = 0.011, P = 0.043, and P = 0.030, respectively). Group 2 showed thinner pRNFL and mGCIPL thickness in general compared with group 1. Conclusions In healthy myopic eyes, superior rotation of the optic disc was more prevalent than inferior rotation. As the optic disc rotates inferiorly, there was a significant positive correlation with IOP, axial length, and area of the β-zone PPA. Conversely, a significant negative correlation with pRNFL and mGCIPL thickness was observed. © 2016 American Academy of Ophthalmology.

Park K.,Chonnam National University | Kwak I.-S.,Chonnam National University
Science of the Total Environment | Year: 2014

Temperature is one of the most important environmental factors affecting the biological processes of aquatic species. To investigate the potential effects of temperature on the developmental processes of aquatic invertebrates, we analyzed biological and molecular transcriptional responses during Chironomus riparius development, including five stages spanning from embryo to adult stages. We assessed the temperature change-induced reduction of survival rate, changes in biological development including the male:female ratio in emerged adults, the success rates of pupation and emergence, and the developmental timing of pupation and emergence. The increased temperature induced expression of endocrine signaling genes, such as the ecdysone receptor, ultraspiracle (ortholog of the RXR), and the estrogen-related receptor in the fourth-instar larval and pupal stages of C. riparius development. Altered temperature also affected the activity of antioxidant genes, including catalase, peroxidase, glutathione peroxidase, and superoxide dismutase during the fourth-instar larval to adult stages of C. riparius development, as a result of altered development. Increased temperature during the fourth-instar larval stage increased oxidative stress in pupae and adults. Responses of antioxidant genes to increased temperature occurred in a developmental stage-dependent manner. However, reduced temperature did not induce the expression of antioxidant genes in a developmental stage-dependent manner, although it did induce oxidative stress during C. riparius development. Increased temperature also caused greater toxicity of di-ethylhexyl phthalate (DEHP) in fourth-instar larvae. Our findings suggest that altered temperatures may disturb the invertebrate hormone system and developmental processes by inducing oxidative stress in aquatic environments. © 2013 Elsevier B.V.

Park S.Y.,Chonnam National University | Chin K.B.,Chonnam National University
International Journal of Food Science and Technology | Year: 2011

The objective of this study was to evaluate the antioxidant activities of pepsin-digested water-soluble protein (WSP) and salt-soluble protein (SSP) extracted from pork ham. WSP and SSP were hydrolysed by pepsin for 2-10 h with 2-h increments. The protein hydrolysates by pepsin were analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, and reducing power of the hydrolysates was measured. In addition, antioxidant activity of the hydrolysates was determined using linoleic acid emulsion system. Protein bands with molecular weight higher than 7 kDa in WSP and SSP were completely hydrolysed by pepsin after 2 h of digestion time. WSP hydrolysates (WSPH) and SSP hydrolysates (SSPH) had higher ferric reducing power than controls (WSP and SSP without pepsin digestion). Reducing powers of WSPH were higher than those of SSPH, regardless of digestion time. The oxidative activity of linoleic acid was predominantly inhibited by the addition of WSPH and SSPH, especially 0.5% protein hydrolysate. These results indicate that several functional peptides of pork protein digested by pepsin might have antioxidant activity, and thus they may be used as an antioxidant agent in muscle food system. © 2011 The Authors. International Journal of Food Science and Technology © 2011 Institute of Food Science and Technology.

Kim Y.S.,Chonnam National University | Ahn Y.,Chonnam National University
Korean Circulation Journal | Year: 2012

The contribution of stem cells to cure damaged hearts has finally been unraveled. A large number of preclinical and clinical studies have showed beneficial outcomes after myocardial infarction. In this review, the current understanding of stem cell therapy in preclinical and clinical experiences is summarized. Stem cells from bone marrow have shown a potential to improve cardiac performance after myocardial infarction in animal and early clinical studies. Clinical trials from all over the world have provided safety assessments of stem cell therapy with marginal improvement of clinical outcomes. Thus, further investigations should be encouraged to resolve the discrepancies between studies, clinical issues, and unclear translational findings. This review provides information and commentary on key trials for stem cell-based treatment of cardiovascular disease. Copyright © 2012 The Korean Society of Cardiology.

Jadhav H.S.,Chonnam National University | Kalubarme R.S.,Chonnam National University | Park C.-N.,Chonnam National University | Kim J.,Chonnam National University | Park C.-J.,Chonnam National University
Nanoscale | Year: 2014

To fulfill the high power and high energy density demands for Li-ion batteries (LIBs) new anode materials need to be explored to replace conventional graphite. Herein, we report the urea assisted facile co-precipitation synthesis of spinel NiCo2O4 and its application as an anode material for LIBs. The synthesized NiCo2O4 exhibited an urchin-like microstructure and polycrystalline and mesoporous nature. In addition, the mesoporous NiCo2O4 electrode exhibited an initial discharge capacity of 1095 mA h g-1 and maintained a reversible capacity of 1000 mA h g-1 for 400 cycles at 0.5 C-rate. The reversible capacity of NiCo2O4 could still be maintained at 718 mA h g-1, even at 10 C. The mesoporous NiCo 2O4 exhibits great potential as an anode material for LIBs with the advantages of unique performance and facile preparation. © 2014 the Partner Organisations.

Yang W.-J.,Chonnam National University | Wang H.-Y.,Chonnam National University | Kim Y.-B.,Chonnam National University
International Journal of Energy Research | Year: 2013

The construction of a reliable numerical model and the clarification of its operational conditions are necessary for maximizing fuel cell operation. Numerous operating factors, such as mole fractions of species, pressure distribution, overpotential, and inlet relative humidity, affect the performance of proton exchange membrane fuel cells (PEMFCs). Among these operational parameters, geometrical shape and relative humidity are investigated in this paper. Specifically, the land ratio of the gas channel and rib is an important parameter affecting PEMFC performance because current density distribution is influenced by this geometrical characteristic. Three main variables determine the current density distribution, namely, species concentration, pressure, and overpotential distributions. These distributions are considered simultaneously in assessing fuel cell performance with a given PEMFC cell-operating voltage. In this paper, three different land ratio models are considered to obtain better PEMFC performance. Similarly, three different inlet relative humidity variations are studied to achieve an enhanced operating condition. A three-dimensional numerical PEMFC model is developed to illustrate the current density distribution as the determining factor for PEMFC performance. © 2012 John Wiley & Sons, Ltd.

Yang K.-H.,Kyonggi University | Song J.-K.,Chonnam National University | Song K.-I.,Chonnam National University
Journal of Cleaner Production | Year: 2013

Although alkali-activated (AA) concrete is generally regarded as one of the most effective concrete technologies for reducing CO 2 emissions, very few investigations have been carried out on the assessment of the CO 2 reduction of such concrete. The present paper reports an evaluation procedure for the CO 2 reduction of AA concrete. The studied system considers all of the steps from the cradle to pre-construction. CO 2 reduction for secondary precast concrete products is also evaluated with reference to practical examples wherein ground granulated blast-furnace slag (GGBS) cement is replaced with AA GGBS binder. Comparisons of the performance efficiency indicators, binder and CO 2 intensities, reveal that the contribution of the binder to the total CO 2 emission is more significant in ordinary Portland cement (OPC)-based concrete than in AA concrete, whereas the contribution of aggregate transportation becomes more critical in AA concrete than in OPC-based concrete. The reduction rate of CO 2 emission of AA concrete relative to OPC concrete commonly ranges between 55 and 75%. In addition, the CO 2 reduction rate in secondary precast concrete products that use AA GGBS binder instead of GGBS cement can be evaluated as approximately 20% when the total aggregate-to-binder ratio ranges between 3.0 and 4.0. On the other hand, Ca(OH) 2-based AA GGBS concrete shows a CO 2 intensity that is approximately 2.4 times lower than that of OPC concrete. Overall, the slope of the increasing rate of the CO 2 intensity against the binder intensity is lower in Ca(OH) 2-based AA GGBS concrete than in OPC-based concrete. © 2012 Elsevier Ltd. All rights reserved.

Choi M.-B.,Chonnam National University | Singh B.,Chonnam National University | Wachsman E.D.,University of Maryland University College | Song S.-J.,Chonnam National University
Journal of Power Sources | Year: 2013

La0.1Sr0.9Co0.8Fe0.2O 3-δ (LSCF1982) and La0.1Sr0.9Co 0.8Fe0.2O3-δ-Ce0.9Gd 0.1O2 (LSCF1982-GDC) composite oxygen electrodes with a GDC barrier layer are tested in yttria stabilized zirconia (YSZ) electrolyte-based reversible solid oxide cells (RSOCs). Three button cell assemblies (1: NiO-YSZ|YSZ/GDC|LSCF1982; 2: NiO-YSZ/NiO-YSZ|YSZ/GDC|LSCF1982; and 3: NiO-YSZ/NiO-YSZ|YSZ/GDC|LSCF1982-GDC) are fabricated and their performance in solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOEC) modes are studied at different temperatures (600 ≤ T/ C ≤ 800). The use of porous NiO-YSZ functional layer between hydrogen electrode and electrolyte leads to improvements in SOFC and SOEC (SOFC/SOEC) performance by improving the diffusion of reacting species inside the electrode. The effect of nature of oxygen electrode on SOFC/SOEC performance is studied, which indicates LSCF1982 oxygen electrode gives better performance than LSCF1982-GDC composite oxygen electrode, but LSCF1982-GDC composite oxygen electrode is more durable during reversible SOFC/SOEC operations. Stability of the button cells is studied in galvanostatic SOEC operation for 72 h and in reversible SOFC/SOEC operations. Current-voltage (I-V) tests and Electrochemical Impedance Spectroscopy (EIS) measurements indicate that the button cells show stable operation in SOEC mode. But successive SOFC → SOEC → SOFC operations indicate that the cells are not completely reversible. The possible reason for poor reversibility is found to be related with the grain growth in LSCF1982-based oxygen electrodes. © 2013 Elsevier B.V. All rights reserved.

Park S.-H.,Chonnam National University | Kim B.-K.,Chonnam National University | Lee W.-J.,Chonnam National University
Journal of Power Sources | Year: 2013

Activated carbon nanofibers with hollow core/highly mesoporous shell structure (Meso-HACNF) are prepared by concentric electrospinning using poly(methyl methacrylate) (PMMA) as a pyrolytic core precursor with either polyacrylonitrile (PAN) or PAN/PMMA blended polymer as a carbon shell precursor, subsequently proceeded to the process of stabilization, carbonization, and activation. Meso-HACNFs with two different PMMA concentrations, 10 wt.% and 20 wt.%, are composed of a highly mesoporous shell and hollow core while HACNF without PMMA is composed of a relatively small mesoporous shell and hollow core. Highly mesoporous Meso-HACNF1 has a large surface area of 1191 m2 g-1 with a mesoporous surface area of 151 m2 g -1. Meso-HACNF1 with 10 wt.% PMMA has a high efficiency of 7.21%, and is comparable to Pt CE because of its novel characteristics, which promote the electron and ion transfer, decrease the resistance of charge transfer, and increase the contact area between liquid electrolyte and Meso-HACNF1. © 2013 Elsevier B.V. All rights reserved.

Aravindan V.,Nanyang Technological University | Gnanaraj J.,Yardney Technical Products, Inc. | Lee Y.-S.,Chonnam National University | Madhavi S.,Nanyang Technological University
Journal of Materials Chemistry A | Year: 2013

Development of an eco-friendly, low cost and high energy density (∼700 W h kg-1) LiMnPO4 cathode material became attractive due to its high operating voltage ∼4.1 V vs. Li falling within the electrochemical stability window of conventional electrolyte solutions and offers more safety features due to the presence of a strong P-O covalent bond. The vacancy formation energy for LiMnPO4 was 0.19 eV higher than that for LiFePO4, resulting in a 10-3 times-diluted complex concentration, which represents the main difference between the kinetics in the initial stage of charging of two olivine materials. This review highlights the overview of current research activities on LiMnPO4 cathodes in both native and substituted forms along with carbon coating synthesized by various synthetic techniques. Further, carbon coated LiMnPO4 was also prepared by a solid-state approach and the obtained results are compared with previous literature values. The challenges and the need for further research to realize the full performance of LiMnPO4 cathodes are described in detail. © 2013 The Royal Society of Chemistry.

Karthikeyan K.,Chonnam National University | Amaresh S.,Chonnam National University | Aravindan V.,Chonnam National University | Aravindan V.,Nanyang Technological University | Lee Y.S.,Chonnam National University
Journal of Materials Chemistry A | Year: 2013

In the present study, a novel attempt has been made to fabricate an asymmetric supercapacitor based on a MgO-multi-walled carbon nanotube (MWCNT) composite as the cathode and activated carbon (AC) as the anode using an organic electrolyte (1 M LiPF6 in EC:DMC 1:1 by volume). Supercapacitance behavior is examined by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge studies. The results reveal that the test cell displayed excellent capacitance performance between 0 and 3 V. The MgO-MWCNT/AC cell delivers a specific capacitance of 66 F g-1 at a current density of 2.2 A g-1. Cycling studies show that this cell can retain 97% of its initial capacitance after 35000 cycles. Additionally, the MgO-MWCNT/AC cell also exhibits a maximum energy density of 30 W h kg -1, which is comparable to the values obtained from other supercapacitor configurations. These results encourage utilization of the MgO-MWCNT composite as a potential electrode in developing green and low cost energy storage devices with high energy and power densities as well as prolonged cycle life. © 2013 The Royal Society of Chemistry.

Singh B.,Chonnam National University | Im H.-N.,Chonnam National University | Park J.-Y.,Chonnam National University | Song S.-J.,Chonnam National University
Journal of Physical Chemistry C | Year: 2013

Sr2+-doped cerium pyrophosphate (Ce1-xSr xP2O7, x = 0.05, 0.1, 0.15, and 0.2) electrolytes are synthesized by digesting cerium oxide and strontium nitrate with 85% H3PO4. The ionic conductivity behavior of Ce 1-xSrxP2O7-sintered pellets is analyzed by electrochemical impedance spectroscopy in a dry and humid air atmosphere. The time-dependent variation of ionic conductivity during humidification process and the variation of conductivity with temperature are studied. In humid atmosphere in the 90-230 C range, the variation of ionic conductivity is explained on the basis of the combined effect of ionic mobility and the availability of charge carriers in the samples. The ionic conductivity shows dependence on dopant concentration and water vapor pressure (pH 2O). In dry air, conductivity of Ce1-xSrxP 2O7 is very low, with Ce0.9Sr 0.1P2O7 showing a maximum conductivity of 4.3 × 10-6 S/cm at 430 C. Among various Ce1-xSr xP2O7 samples, Ce0.9Sr 0.1P2O7 shows the highest conductivity in humid air (pH2O = 0.12 atm) with a maximum conductivity of 6.3 × 10-3 S/cm at 90 C, and the conductivity of Ce0.9Sr 0.1P2O7 was 3.5 × 10-3 S/cm at 190 C and pH2O = 0.12 atm. On the basis of XRD results, the stability of Ce1-xSrxP2O7 in a humid atmosphere is analyzed. © 2013 American Chemical Society.

Su J.,CAS Institute of Chemistry | Wu X.-L.,CAS Institute of Chemistry | Lee J.-S.,Chonnam National University | Kim J.,Chonnam National University | And 2 more authors.
Journal of Materials Chemistry A | Year: 2013

A facile sol-gel approach combined with a carbon-coating technique via high-temperature thermally decomposing C2H2 has been developed for the synthesis of a Li3V2(PO 4)3/C (LVP/C) cathode material employing the biomass of phytic acid as an eco-friendly phosphorus source. The effects of the carbon-coating on the structural, morphological and electrochemical properties of LVP have been investigated. Compared with pristine LVP, the LVP/C composite presents a higher discharge capacity of 127 mA h g-1 at 0.1 C, better rate capability and long-term cyclability in the voltage range of 3.0-4.3 V. Even at a high charge-discharge rate of 5 C, it can still deliver a reversible capacity of 107 mA h g-1 over 400 cycles without obvious fading, demonstrating great potential as a superior cathode material for lithium-ion batteries. © 2013 The Royal Society of Chemistry.

Kim Y.-J.,Massachusetts Institute of Technology | Ahn S.-J.,Chonnam National University | Hwang P.-I.,Seoul National University | Pyo G.-C.,Seoul National University | Moon S.-I.,Seoul National University
IEEE Transactions on Power Systems | Year: 2013

This paper presents a new control method, in which a distributed generator (DG) actively participates in steady-state voltage control, together with an under-load tap changer (ULTC) and shunt capacitors (Sh.Cs). In the conventional DG control method, the integration of DGs into a distribution power system increases the number of switching operations of the ULTC and the Sh.Cs. To solve this problem, this paper proposes that the DG output voltage be dispatched cooperatively with the operation of the ULTC and the Sh.Cs, based on load forecasts for one day in advance. The objective of the proposed method is to decrease the number of switching device operations, as well as to reduce the power loss in the distribution lines, while maintaining the grid voltage within the allowed range. The proposed method is designed and implemented with Matlab, using two different dynamic programming algorithms for a dispatchable and a nondispatchable DG, respectively. Simulation studies demonstrate that the objective can be achieved under various grid conditions, determined by factors such as the DG output power characteristics, the location of the DG-connected bus on the feeder, and the load profile of the feeder containing the DG. © 2012 IEEE.

This study examines the existing and anticipated technology strategies for reducing greenhouse gas (GHG) emissions in Korea's petrochemical and steel industries. The results of the cluster analysis identify three types of technology strategies employed by firms for reducing GHG emissions: "wait-and-see" "in-process-focused", and "all-round" strategies. The "in-process-focused" strategy was the most widely used strategy, followed by the "all-round" strategy. However, firms in these industries are expected to change their technology strategies to "treatment-reliance", "inbound- substitution", and "all-round" strategies in 5-10 years by employing a wider range of technology options to respond more effectively to the issue of GHG emissions. The demand for new energy sources and raw material substitutes is expected to strengthen in the near future as related technologies advance rapidly and become more widely available. © 2010 Elsevier Ltd. All rights reserved.

Yu H.,CAS Shanghai Institute of Microsystem and Information Technology | Xu P.,CAS Shanghai Institute of Microsystem and Information Technology | Lee D.-W.,Chonnam National University | Li X.,CAS Shanghai Institute of Microsystem and Information Technology
Journal of Materials Chemistry A | Year: 2013

With oleylamine as a solvent and reducing agent, Au nanoparticles (AuNPs) are grown in situ on graphene oxide (GO) sheets. Thereafter, a porous-layered stack of AuNPs-GO nanosheets is formed by a gas-phase chemical reduction step. After the AuNPs are modified with 11-mercaptoundecanoic acid (11-MUA) to graft -COOH sensing groups to the amine, the functionalized AuNPs-rGO porous-layer stacked nanosheets are loaded onto a gravimetric resonant microcantilever for use as a mass sensing material. The rGO sheets serve as multi-layer nano-shelves to support and carry the functionalized AuNPs for gas adsorbing/sensing, while the AuNPs serve as nano-spacers between the rGO sheets to provide a high specific surface area for gas molecules accessing the material. The cantilever sensor experimentally exhibits a very rapid response to ppm-level trimethylamine (TMA) vapor, which is attributed to the novel sensing material. Compared with the hydrophilic AuNP-GO, the highly hydrophobic AuNP-rGO shows a much improved suppression to the noise from changes in environmental humidity. Featuring a rapid response, high sensitivity and good resistance to interference from environmental moisture, the novel sensing nanomaterial is promising in various chemical vapor detection applications. This journal is © The Royal Society of Chemistry.

Lee Y.S.,Massachusetts Institute of Technology | Heo J.,Harvard University | Heo J.,Chonnam National University | Siah S.C.,Massachusetts Institute of Technology | And 5 more authors.
Energy and Environmental Science | Year: 2013

We demonstrate a tunable electron-blocking layer to enhance the performance of an Earth-abundant metal-oxide solar-cell material. A 5 nm thick amorphous ternary metal-oxide buffer layer reduces interface recombination, resulting in sizable open-circuit voltage and efficiency enhancements. This work emphasizes the importance of interface engineering in improving the performance of Earth-abundant solar cells. © The Royal Society of Chemistry 2013.

Woo J.S.,Kyung Hee University | Kim W.,Kyung Hee University | Ha S.J.,Kyung Hee University | Kim J.B.,Kyung Hee University | And 4 more authors.
Arteriosclerosis, Thrombosis, and Vascular Biology | Year: 2013

Objective-Experimental evidence suggests that exenatide, a glucagon-like peptide 1 receptor analogue, has significant cardiovascular protective effects in various conditions. We examined whether routine use of exenatide at the time of primary percutaneous coronary intervention would reduce infarct size in patients with ST-segment-elevation myocardial infarction. Approach and Results-Fifty-eight patients with ST-segment-elevation myocardial infarction and thrombolysis in myocardial infarction flow 0 were enrolled in the study and randomly assigned to receive either exenatide or placebo (saline) subcutaneously. Infarct size was assessed by measuring the release of creatine kinase-MB and troponin I during 72 hours and by performing cardiac magnetic resonance imaging at 1 month after infarction. Routine and speckle tracking echocardiography was performed at initial presentation and at 3 days and 6 months after primary percutaneous coronary intervention. The exenatide and control groups had similar results with respect to ischemia time, demographic characteristics, and ejection fraction before primary percutaneous coronary intervention. The releases of creatine kinase-MB and troponin I were significantly reduced in the exenatide group. In 58 patients evaluated with cardiac magnetic resonance, the absolute mass of delayed hyperenhancement was significantly reduced in the exenatide group as compared with the control group (12.8±11.7 versus 26.4±11.6 g; P<0.01). At 6 months, the exenatide group showed a significantly lower value of E/E′ with improved strain parameters. No significant adverse effects of exenatide administration were detected. Conclusions-In patients with ST-segment-elevation myocardial infarction, adjunctive exenatide therapy with primary percutaneous coronary intervention was associated with reduction of infarct size and improvement of subclinical left ventricular function. © 2013 American Heart Association, Inc.

Senthilkumar S.T.,Bharathiar University | Selvan R.K.,Bharathiar University | Ponpandian N.,Bharathiar University | Melo J.S.,Bhabha Atomic Research Center | Lee Y.S.,Chonnam National University
Journal of Materials Chemistry A | Year: 2013

Electric double layer capacitors (EDLCs) were fabricated using biomass derived porous activated carbon as electrode material with 1 M H 2SO4 and VOSO4 added 1 M H2SO 4 as electrolytes. Here, VOSO4 was used as redox additive to improve the overall performance of EDLC. As expected, the VOSO4 electrolyte showed ∼43% of improved specific capacitance of 630.6 F g -1 at 1 mA cm-2 compared to pristine 1 M H 2SO4 (440.6 F g-1) due to the contribution of VO2+/VO2 + redox reaction at the electrode-electrolyte interface. Possible redox reaction mechanism of VO 2+/VO2 + pair is also briefly illustrated. The good cycling performance of 97.57% capacitance retention was observed even after 4000 cycles. For comparison, the polymer gel electrolyte (PVA/VOSO 4/H2SO4) was also prepared and then the performance of the fabricated EDLCs was studied. Overall, these findings could open up a simple and cost effective way to improve the performance of EDLCs significantly. © 2013 The Royal Society of Chemistry.

Wang Y.-X.,Chonnam National University | Xuan D.-J.,Wenzhou University | Kim Y.-B.,Chonnam National University
International Journal of Hydrogen Energy | Year: 2013

This paper studies the air flow control for preventing the starvation and/or obtaining the maximum net power of a Polymer Electrolyte Membrane (PEM) fuel cell system using time delay control (TDC). Feedforward and feedback controls are utilized simultaneously to prevent air shortage during the transient response of the fuel cell operation. The TDC algorithm design is created with a low-order dynamic model, and its superior performances are proven using a real-time control experiment. The optimal air excess ratio is calculated experimentally given the variation of the external load, and the net power increase is discussed by comparison with the results obtained from fixed air excess ratio. The Ballard 1.2 kW PEM fuel cell system is used for the experiments as a test rig, and the LabView system is used for the real-time air flow control. The superiority of the TDC performance is proven by comparison with other control algorithms such as the proportional-integral control (PIC), feedforward control, and the original manufacturer's control. The proposed control algorithm can improve PEM fuel cell system performance by preventing air shortage and/or by obtaining higher performance. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Kim H.,Seoul National University | Cho M.-Y.,Korea Institute of Ceramic Engineering And Technology | Kim M.-H.,Korea Institute of Ceramic Engineering And Technology | Park K.-Y.,Seoul National University | And 4 more authors.
Advanced Energy Materials | Year: 2013

A hybrid supercapacitor with high energy and power densities is reported. It comprises a composite anode of anatase TiO2 and reduced graphene oxide and an activated carbon cathode in a non-aqueous electrolyte. While intercalation compounds can provide high energy typically at the expense of power, the anatase TiO2 nanoparticles are able to sustain both high energy and power in the hybrid supercapacitor. At a voltage range from 1.0 to 3.0 V, 42 W h kg-1 of energy is achieved at 800 W kg-1. Even at a 4-s charge/discharge rate, an energy density as high as 8.9 W h kg-1 can be retained. The high energy and power of this hybrid supercapacitor bridges the gap between conventional batteries with high energy and low power and supercapacitors with high power and low energy. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lee I.C.,Pohang University of Science and Technology | Hong S.W.,Chonnam National University | Whang S.S.,Chonbuk National University | Lim P.O.,Jeju National University | And 2 more authors.
Plant and Cell Physiology | Year: 2011

Leaf senescence, which constitutes the final stage of leaf development, involves programmed cell death and is intricately regulated by various internal and environmental signals that are incorporated with age-related information. ABA plays diverse and important physiological roles in plants, and is involved in various developmental events and stress responses. ABA has long been regarded as a positive regulator of leaf senescence. However, the cellular mediators of ABA-induced senescence have not been identified. We sought to understand the ABA-induced senescence signaling process in Arabidopsis by examining the function of an ABA- and age-induced gene, RPK1, which encodes a membrane-bound, leucine-rich repeat-containing receptor kinase (receptor protein kinase 1). Loss-of-function mutants in RPK1 were significantly delayed in age-dependent senescence. Furthermore, rpk1 mutants exhibited reduced sensitivity to ABA-induced senescence but little change to jasmonic acid- or ethylene-induced senescence. RPK1 thus mediates ABA-induced leaf senescence as well as age-induced leaf senescence. Conditional overexpression of RPK1 at the mature stage clearly accelerated senescence and cell death, whereas induction of RPK1 at an early developmental stage retarded growth without triggering senescence symptoms. Therefore, RPK1 plays different roles at different stages of development. Consistently, exogenously applied ABA affected leaf senescence in old leaves but not in young leaves. The results, together, showed that membrane-bound RPK1 functions in ABA-dependent leaf senescence. Furthermore, the effect of ABA and ABA-inducible RPK1 on leaf senescence is dependent on the age of the plant, which in part explains the mechanism of functional diversification of ABA action. © 2011 The Author.

Yoon K.-C.,Chonnam National University | Im S.-K.,Chonnam National University | Park H.-Y.,Chonnam National University
Cornea | Year: 2010

Purpose: To report a case of recurrent herpes simplex keratitis after verteporfin photodynamic therapy for corneal neovascularization. Methods: A 69-year-old man who had lipid keratopathy with corneal neovascularization secondary to herpes simplex keratitis in the right eye and who was treated with topical steroid received photodynamic therapy with verteporfin. Six neovascular areas in the cornea were treated consecutively to occlude new vessels and reduce the risk of allograft rejection after subsequent keratoplasty. Results: Three days after verteporfin photodynamic therapy, there was evidence of vascular occlusion. However, a herpetic epithelial ulcer was detected in the cornea. Ten days after treatment, the lesion progressed to a geographic ulcer. After topical and systemic acyclovir treatment, the lesion healed. Five months after treatment, penetrating keratoplasty and postoperative antiviral prophylaxis were performed. During a follow-up period of 12 months, the graft remained clear with visual acuity of 20/40. Conclusion: Herpes simplex keratitis can recur after verteporfin photodynamic therapy for corneal neovascularization. © 2010 Lippincott Williams & Wilkins.

Kim S.H.,Chonnam National University | Kim K.H.,Chonnam National University | Lim J.W.,Chonnam National University | Kim J.N.,Chonnam National University
Tetrahedron Letters | Year: 2014

An expedient oxidative phosphorylation of pyrroles has been disclosed. The reaction of dialkyl phosphite and pyrrole in the presence of AgNO 3/K2S2O8 in DMF/H2O (8:1) produced pyrrole-2-phosphonates in good yields. In the absence of dialkyl phosphite, γ-hydroxy-γ-butyrolactam derivative was formed as a major product. © 2013 Elsevier Ltd. All rights reserved.

Sethna F.,Michigan State University | Moon C.,Chonnam National University | Wang H.,Michigan State University
Neurochemical Research | Year: 2014

Fragile X syndrome (FXS) is caused by mutations in the fragile X mental retardation 1 (FMR1 ) gene. Most FXS cases occur due to the expansion of the CGG trinucleotide repeats in the 5′ un-translated region of FMR1, which leads to hypermethylation and in turn silences the expression of FMRP (fragile X mental retardation protein). Numerous studies have demonstrated that FMRP interacts with both coding and non-coding RNAs and represses protein synthesis at dendritic and synaptic locations. In the absence of FMRP, the basal protein translation is enhanced and not responsive to neuronal stimulation. The altered protein translation may contribute to functional abnormalities in certain aspects of synaptic plasticity and intracellular signaling triggered by Gq-coupled receptors. This review focuses on the current understanding of FMRP function and potential therapeutic strategies that are mainly based on the manipulation of FMRP targets and knowledge gained from FXS pathophysiology. © Springer Science+Business Media 2013.

Jeong O.,Chonnam National University | Park Y.K.,Chonnam National University | Ryu S.Y.,Chonnam National University | Kim Y.J.,Chonnam National University
Annals of Surgical Oncology | Year: 2010

Background and Purpose. As a life expectancy increases, the proportion of aged patients diagnosed with gastric cancer has increased over the past decades, but the optimal surgical approach to these patients remains a dilemma because of the presumed risk associated with extended surgery. Methods. A total of 383 consecutive patients who underwent gastrectomy with D2 lymph node dissection in 2008 and 2009 were enrolled onto this study. Patients were divided into two age groups (<70 vs. ≥70 years) and were prospectively evaluated with respect to postoperative complications and hospital courses. Results. The cohort consisted of 101 elderly and 282 nonelderly patients. No statistically significant differences were evident between the two groups with respect to clinicopathological parameters and operations performed, except for preoperative comorbidity rates and mean American Society of Anesthesiologists scores. Surgical complication rates in the elderly and nonelderly groups were 18.8 and 17.4%, respectively (P = 0.746), and medical complication rates were 5.0 and 1.8%, respectively (P = 0.137). The two groups were not statistically significantly different in terms of mean length of hospital stays, times to diet start, or required transfusion. Multivariate analysis showed that body mass index, male sex, and distal pancreatectomy were independent risk factors of a surgical complication, and that comorbidity and operating time were independently associated with a medical complication. Conclusions. This study shows that age neither increased postoperative morbidity nor negatively affected hospital courses after gastrectomy with D2 lymph node dissection. Accordingly, chronologic age alone should not preclude standard gastrectomy with extended lymph node dissection in gastric carcinoma. © Society of Surgical Oncology 2010.

Huh J.W.,Chonnam National University | Kim H.R.,Chonnam National University | Kim Y.J.,Chonnam National University
Annals of Surgical Oncology | Year: 2010

Background: Perineural invasion (PNI) may influence the prognosis after resection of colorectal cancer (CRC); whether this is a definite prognostic factor remains controversial. This study determined the clinicopathologic factors associated with oncologic outcome after radical resection of stage II CRC, focusing on PNI. Materials and Methods: We retrospectively reviewed 341 consecutive patients who underwent curative surgery for stage II CRC between January 2001 and December 2006. Of these, 278 patients (81.5%) received postoperative 5-fluorouracil-based chemotherapy. The oncologic outcomes and the risk factors for recurrence were analyzed. Results: PNI was detected in 57 of 341 patients (16.7%) and was significantly associated with depth of tumor invasion (P =.035) and positive lymphovascular invasion (P <.001). Multivariate analyses revealed that PNI was a significant independent prognostic factor for disease-free survival, not for overall survival. With a median follow-up period of 57.6 months, the 5-year disease-free and overall survival rates of the patients were 80.2 and 82.6%, respectively. The 5-year disease-free survival of the PNI-negative group was significantly higher than that of the PNI-positive group (P <.001). Within the PNI-positive patients, those receiving chemotherapy had significantly higher 5-year disease-free survival than the others (P =.023). ConclusionL This study illustrates the value of PNI as a prognostic factor for stage II CRC. Moreover, PNI-positive patients should be considered for postoperative chemo-therapy. © Society of Surgical Oncology 2010.

Choi I.S.,Chonnam National University | Kim J.-H.,Jeju National University | Wi S.G.,Chonnam National University | Kim K.H.,Chonnam National University | Bae H.-J.,Chonnam National University
Applied Energy | Year: 2013

In this study, we designed a biomass popping pretreatment, system using a fired burner and a horizontal cylinder rotating on an axis, to produce ethanol from mandarin (Citrus unshiu) peel (MP) waste. Popping pretreatment was performed at 150 °C for 10. min without chemical treatment. Popping pretreatment reduced the size of particles to less than 1. mm and decreased the concentration of d-limonene, a yeast fermentation inhibitor, from 0.21% to 0.01%. Enzymatic hydrolysis of pretreated MP was performed in 50. mM sodium acetate buffer (pH 4.8) at 45 °C for 6. h, and the total saccharification rate was approximately 95.6%. The vacuum evaporation process increased the fermentable sugar concentration to 10% (glucose 7.1% and fructose 2.9%). Subsequent fermentation at 30 °C at pH 5.0 for 12. h in a laboratory bioreactor increased the ethanol yield to 90.6%, compared to 78% at 36. h from raw MP. © 2012 Elsevier Ltd.

Ahn J.K.,Chonnam National University
Ocular Immunology and Inflammation | Year: 2010

Purposes: To investigate morphologic changes in anterior segments based on inflammatory phases of Vogt-Koyanagi-Harada (VKH). Methods: The author recruited 76 consecutive eyes of 38 patients with initial-onset VKH and 52 eyes of 26 patients with recurrent VKH. Morphologic changes in anterior segments were measured by ultrasound biomicroscopy (UBM). UBM parameters and intraocular pressure (IOP) were compared between two groups. Results: Ciliary thickness and area significantly increased in the recurrent group compared with the initial-onset group. Twelve patients (31%) in the initial-onset group showed supraciliary effusions, but no patients in the recurrent group had supraciliary effusions. Angle opening and anterior chamber depth were significantly decreased in the initial-onset group compared with the recurrent group. High IOP > 30 mmHg was found in 7 patients with initial-onset disease, while low IOP < 10 mmHg was detected in 6 patients with recurrent disease. Conclusions: The results indicate that morphologic changes associated with IOP alterations depend on inflammatory phases of VKH disease. © 2010 Informa Healthcare USA, Inc.

Noh H.-R.,Chonnam National University
Journal of the Korean Physical Society | Year: 2014

We present analytical solutions for the populations of the D1 transition line of 85Rb atoms. The time evolution of the populations of the magnetic sublevels in the excited state at the weak intensity limit exhibits several kinds of homogeneous or inhomogeneous second-order differential equations. General solutions of the differential equations result in an analytical form of the population in each magnetic sublevel as a function of the elapsed time, laser intensity, and laser frequency detuning. © 2014 The Korean Physical Society.

Cha K.S.,Chonbuk National University | Bae J.H.,Chonnam National University
Energy Policy | Year: 2011

This study investigates the impacts of high international oil prices on the bioethanol and corn markets in the US. Between 2007 and 2008, the prices of major grain crops had increased sharply, reflecting the rise in international oil prices. These dual price shocks had caused substantial harm to the global economy. Employing a structural vector auto-regression model (SVAR), we analyze how increases in international oil prices could impact the prices of and demand for corn, which is used as a major bioethanol feedstock in the US. The results indicate that an increase in the oil price would increase bioethanol demand for corn and corn prices in the short run and that corn prices would stabilize in the long run as corn exports and feedstock demand for corn decline. Consequently, policies supporting biofuels should encourage the use of bioethanol co-products for feed and the development of marginal land to mitigate increases in the feedstock price. © 2010 Elsevier Ltd.

The numerical conditions to generate high-purity {pipe}1 >, {pipe}2 >, and {pipe}1 > + re iψ{pipe}2 > states were found from the explicit form of the probability amplitudes for two cascade-placed beam splitters with one squeezed state input and two coherent state inputs. The expected theoretical signal-tonoise ratio is more than 1000. Controlling the amplitudes and the phases of two coherent beams, as well as the transmittances of two beam splitters, allow various quantum states to be manipulated with a high signal-to-noise ratio. High-purity nonclassical states are expected to be a key element in quantum information science. © 2014 The Korean Physical Society.

The spread of smartphones triggers the universal use of smartphone-based social networking services (SNS) by satisfying users' needs for maintaining seamless, constant connection and developing intimate relationships with others, such as family, friends, and acquaintances. Under the circumstances, this study examines the consequences of ubiquitous connectivity, considering that it is a typical characteristic of mobile technologies. More specifically, this study addresses both sides of ubiquitous connectivity due to smartphone-based SNS namely, social presence and privacy concern. Furthermore, the study verifies the role of enjoyment which has been argued as a key determinant of the continued use of hedonic IS. The results show that first, ubiquitous connectivity increases social presence and privacy concern simultaneously. Second, enjoyment derives from not only ubiquitous connectivity but also social presence and privacy concern. Finally, smartphone-based SNS continuance intention is determined by enjoyment, social presence, and privacy concern. Discussion and implications on the results are presented. © 2016

Lee Y.,Chonnam National University
Journal of Physiological Anthropology | Year: 2015

Background: Anthropometric surveys devised by each country attempt to fulfill the requirements of the manufacturers, designers, and human welfare device production, providing them with data and tools and allowing them to face both the internal and export markets. To this end, national anthropometric data collections and comparisons including three-dimensional information, together with comparison of these data among countries, are conducted at both the domestic and global levels. Methods: The anthropometric data of the Korean population measured in 2013 (Korean Agency for Technology and Standard (KATS) 2013 data) and the data collected from 2010 (KATS 2010 data) that was conducted on 710 males between the ages of 13 and 18years were analyzed in this section to obtain information on Korean boy's physical features and growth. Results: The mean height increased about 5cm from 13 to 14years which shows the early fast maturing somatotype. Also, the mean height of boys aged from 15 to 16 increased about 1 to 2cm. For the results of body proportion rate index against height, they show 0.93, 0.81, 0.38, 0.99, and 0.26 times the height in eye height, shoulder height, fingertip height, and span and maximum shoulder breadth, respectively, in 16-year-old boys. For the body mass index, the weight is increased from the age of 16years. Conclusions: There are several studies that cover growth features of the entire range from birth to maturity, and they have reported the comparison of the growth patterns among Europeans. Even though such researches have been made, as for the industry, the human modeling tools based on the anthropometric data and morphological features that cover all the countries should be developed for well-fit garments and other human-oriented design process. © 2015 Lee; licensee BioMed Central.

Nguyen M.-K.,Nguyen Tat Thanh University | Lim Y.-C.,Chonnam National University | Park S.-J.,Chonnam National University
IEEE Transactions on Power Electronics | Year: 2013

This paper deals with a new family of high boost voltage inverters that improve upon the conventional trans-Z-source and trans-quasi-Z-source inverters. The improved trans-Z-source inverter provides continuous input current and a higher boost voltage inversion capability. In addition, the improved inverter can suppress resonant current at startup, which might destroy the device. In comparison to the conventional trans-Z-source/-trans-quasi-Z-source inverters, for the same transformer turn ratio and input and output voltages, the improved inverter has a higher modulation index with reduced voltage stress on the dc link, lower current stress flow on the transformer windings and diode, and lower input current ripple. In order to produce the same input and output voltage with the same modulation index, the improved inverter uses a lower transformer turn ratio compared to the conventional inverters. Thus, the size and weight of the transformer in the improved inverter can be reduced. This paper presents the operating principles, analysis and simulation results, and compares them with those of the conventional trans-Z-source/-quasi-Z-source inverters. To verify the performance of the improved converter, a laboratory prototype was constructed based on a TMS320F2812digital signal processor with 100V $\rm dc input and 115V $\rm rms output voltage. © 1986-2012 IEEE.

Wi J.H.,Chonnam National University | Soh H.Y.,Chonnam National University
Journal of Natural History | Year: 2013

Identification for Farranula species has hitherto been carried out with reference to several fragmentary figures and incomplete descriptions of species from the temperate and tropical oceans. As a result, many identification errors such as mixing of characters of different species and confusing two species have occurred in many taxonomic and ecological studies. It is apparent that morphological details such as mouthparts, relative lengths of endopodal spines of swimming legs, ornamentation on surface of genital somite and length: width proportions are needed to verify taxonomic status. In this study, distinct morphological characters differentiating the genus Farranula from other genera within Corycaeidae are discussed on the basis of detailed redescriptions of Farranula concinna and Farranula gibbula from southern waters off Jeju Island, Korea (East China Sea). This is the first record of F. concinna from Korean Waters. © 2013 Copyright Taylor and Francis Group, LLC.

Suh H.N.,Chonnam National University | Han H.J.,Seoul National University
Journal of Cellular Physiology | Year: 2011

Adhesion of cells to extracellular matrix (ECM) influences vital aspects of anchorage-dependent cell behavior including survival, proliferation, and differentiation. However, the role of collagen I in mouse embryonic stem cells (mESCs) is not well-known. Therefore, in the present study we examined the effect of collagen I on mESC self-renewal and related signal pathways. Collagen I (10μg/ml) maintained mESCs in an undifferentiated state (Nanog, OCT4, and SSEA-1) and did not affect differentiation (GATA4, Tbx5, Fgf5, and Cdx2) in the presence of leukemia inhibitory factor (LIF). Treatment with collagen I bound both α2β1 integrin and discoidin domain receptor 1 (DDR1), and stimulated intracellular signaling pathways. Collagen I-bound α2β1 integrin increased integrin-linked kinase (ILK) phosphorylation, cleaved Notch protein expression in the nuclear fraction, and Gli-1 mRNA expression. In addition, collagen I-bound DDR1 increased GTP-bound Ras, phosphoinositide 3-kinase (PI3K) p85α catalytic subunit protein expression, and Akt and ERK phosphorylation. Importantly, collagen I increased Bmi-1 protein expression in the nucleus which was blocked by small interfering RNA (siRNA) specific for Gli-1 and ERK, showing that parallel pathways of integrins and DDR1 merge at Bmi-1. Furthermore, collagen I-induced p16 decrease and p-Rb increase were reversed by Bmi-1-specific siRNA. Moreover, Bmi-1 silencing abolished the collagen I-induced increase of proliferation indices and undifferentiation markers. These results indicate that collagen I stimulates the self-renewal of mESCs mediated by Bmi-1 through α2β1 integrin-dependent ILK, Notch, Gli-1, and DDR1-dependent Ras, PI3K/Akt, and ERK. © 2011 Wiley-Liss, Inc.

Huh J.W.,Sungkyunkwan University | Kim H.R.,Chonnam National University | Kim Y.J.,Chonnam National University
Journal of the American College of Surgeons | Year: 2013

Background: The current study was performed to examine the prognostic role of 53 messenger ribonucleic acid (mRNA) expression in patients with colorectal cancer and analyze its relationship with the expression of CD44 and CD133 mRNA levels. Study Design: We retrospectively reviewed 137 consecutive patients who underwent curative surgery for stage I to III colorectal cancer in 2006. Prognostic factors, including wild-type (wt) p53, cyclooxygenase-2, CD44, and CD133 mRNA levels, were determined using reverse transcriptase polymerase chain reaction and clinical outcomes were analyzed. Results: Wild-type p53 mRNA expression was correlated with the expression of CD44 and CD133 mRNA (p = 0.005 and p = 0.013, respectively). With a median follow-up period of 64 months, the 5-year disease-free survival rate of patients with elevated wt-p53 mRNA expression was significantly higher than that of those patients with low levels of wt-p53 mRNA expression (84.9% and 67.6%, respectively; p = 0.014). A multivariate analysis identified 3 independent factors that substantially affected the disease-free survival: depth of tumor invasion, lymph node metastasis, and wt-p53 mRNA expression. The 5-year disease-free survival rate in patients with stage III or rectal tumors differed significantly between the low and high wt-p53 expression groups. In stage III cancers, high wt-p53 expression was associated with better survival than low wt-p53 expression in patients treated with adjuvant chemotherapy (p = 0.005). A significant association between combined p53/CD44 expression and survival was evident (p = 0.006). Conclusions: Expression of p53 mRNA is a useful predictor of survival in patients with stage III or rectal cancers, with a significant association with CD44 mRNA expression. © 2013 by the American College of Surgeons.

Jeong G.Y.,Chonnam National University
Forest Products Journal | Year: 2016

The goal of this study was to integrate forest management practice with the mechanical properties of oriented strand boar (OSB). Modulus of elasticity (MOE), modulus of rupture (MOR), and internal bond strength (IBS) were determined fro OSB panels made from control, thinned, and fertilized trees. Different trends were associated with growth ring counts an heights of the feedstock trees. The mechanical properties were not dependent on the density profiles. MOE and IBS from th different forest managed trees were strongly correlated with different anatomical structures. However, the MOR of panel made trees from different forest management schemes was not strongly correlated with any anatomical structures but wa strongly correlated with MOE. ©Forest Products Society 2016.

Park S.S.,Chonnam National University | Cho S.Y.,Chonnam National University
Aerosol and Air Quality Research | Year: 2013

Between 20 March and 4 April, 2010, 24-hr PM2.5 measurements were carried out at an urban site in Gwangju, Korea, to examine the variations in the composition of its chemical constituents among dust storm (DS) events, haze pollution, and typical sampling (TS) conditions. A very heavy Asian DS (DS1) and a minor DS (DS2) occurred at the site on 20 and 23 March, 2010, respectively. The concentrations of organic matter, NO3 -, SO4 2-, and the predicted crustal material made a contribution to the observed PM2.5 of 12.9, 9.7, 12.9, and 36.9% for DS1, 23.8, 17.1, 9.9, and 29.7% for DS2, and 24.9, 20.2, 10.3, and 17.6% for the haze event, respectively. Over the study period, the water-soluble organic carbon (WSOC)/OC and hydrophilic WSOC (WSOCHPI)/WSOC ratios ranged from 0.35 to 0.54 and from 0.15 to 0.61, respectively, with the highest ratios occurring during DS1. The concentration of WSOCHPI during DS1 was about 2-3 times higher than that during the TS period. The strong correlation between WSOC/OC and WSOCHPI/WSOC (R2 = 0.84) clearly indicates that the increase in the WSOC/OC ratio can be attributed to the increased concentration of WSOCHPI, suggesting that the aerosol sample collected during DS1 was more aged or atmospherically processed than the samples collected during the TS. In addition to the association between the WSOC/OC and WSOCHPI/WSOC ratios, strong correlations between the oxalate and SO4 2- concentrations (R2 = 0.74), and between the WSOCHPI and SO4 2- concentrations (R2 = 0.69), suggest that the WSOCHPI observed at the site was produced by atmospheric transformation processes similar to those seen with SO4 2- and oxalate. In contrast, the hydrophobic WSOC (WSOCHPO) concentration dominated in the other sampling periods, except for DS1, and accounted for 71.1-84.7% of WSOC. Based on the results of previous studies, the higher WSOCHPO/WSOC ratio during the TS indicates that the primary combustion emissions were important sources of the WSOCHPO fraction at this site. © Taiwan Association for Aerosol Research.

Nishizawa T.,Chonnam National University | Takami I.,Tsushima Fisheries Expansion Advisory Center | Yang M.,Chonnam National University | Oh M.-J.,Chonnam National University
Vaccine | Year: 2011

The process of " Poly(I:C) immunization" involves immunization of fish with a pathogenic live virus, followed by administration of Poly(I:C), which induces a transient, non-specific antiviral state. As a result, fish in an antiviral state survive the initial immunization with live virus. Moreover, these fish are able to mount a specific protective immune response against the injected pathogenic virus. In the present study, we investigated the optimum temperature for Poly(I:C) immunization of Japanese flounder Paralichthys olivaceus with live viral hemorrhagic septicemia virus (VHSV). It was revealed that the optimum temperature was around at 17°C for Poly(I:C) immunization in Japanese flounder. Furthermore, the protection efficacy of Poly(I:C) immunization was significantly decreased by elevation of fish rearing temperature, and no efficacy was observed at a fish rearing temperature of 25°C. Interestingly, no mortality by VHSV infection was observed in fish reared at 21°C and 25°C even when those fish were not administered Poly(I:C). All of the survivors from the first VHSV-challenge at 21°C were strongly protected from re-challenge with VHSV. However, almost all of the survivors (≥82.6%) from the first challenge at 25°C were lost by the second challenge with VHSV. It was thus concluded that by rearing fish at 21°C and challenging with live VHSV, it is possible to induce strong specific immunity in Japanese flounder without Poly(I:C) administration. © 2011 Elsevier Ltd.

Park S.P.,Hallym University | Ahn J.K.,Chonnam National University | Mun G.H.,Chonnam National University
Retina | Year: 2010

Purpose: The purpose of this study was to determine whether aqueous levels of vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF) are associated with developments of serous retinal detachment (SRD) secondary to branch retinal vein occlusion. Methods: We recruited 102 patients with branch retinal vein occlusion and 10 controls. We divided patients into two groups according to optical coherence tomography images of the macula. Forty-six of 102 patients showed SRD defined as being subretinal fluid accumulation with low reflectivity, and the remaining 56 patients presented only cystoid macular edema (CME) defined as being hyporeflective intraretinal cavities. We measured the extent of vascular leakage (disk areas) by digital fluorescein angiography and evaluated the retinal ischemia defined as capillary nonperfusion. Aqueous concentrations of VEGF and pigment epithelium-derived factor were measured by enzyme-linked immunosorbent assay and compared between the two groups. Results: The incidence of major branch retinal vein occlusion was higher in the SRD group (38 of 46, 83%) than in the CME group (32 of 56, 66%, P = 0.01). The incidences of ischemic vein occlusion and macular ischemia was similar between the SRD group (18 of 46 and 20 of 46) and the CME group (20 of 56 and 24 of 56), whereas vascular leakage areas were larger in the SRD group than in the CME group (P = 0.02). Aqueous VEGF levels were higher in the SRD group than in the CME group (P < 0.001), whereas aqueous pigment epithelium-derived factor levels were similar. Vascular endothelial growth factor levels were positively correlated with pigment epithelium-derived factor levels (P < 0.001). Conclusion: Our results indicate that excessive increase in vascular permeability because of VEGF upregulation may contribute to the development of SRD secondary to branch retinal vein occlusion. Copyright © by Ophthalmic Communications Society, Inc.

Park J.H.,Chonnam National University | Ryu J.M.,Chonnam National University | Han H.J.,Chonnam National University
Journal of Cellular Physiology | Year: 2011

Fibronectin (FN) is the foremost proliferation-associated extracellular matrix component promoting cell adhesion, migration, and survival. We examined the effect of FN on cell proliferation and the related signaling pathways in mouse embryonic stem (ES) cells. FN increased integrin β1, Src, focal adhesion kinase (FAK), and caveolin-1 phosphorylation levels in a time-dependent manner. Phosphorylation of Src, FAK, and caveolin-1 was attenuated by integrin β1 neutralizing antibody. Integrin β1, Src, and FAK coimmunoprecipitated with caveolin-1 in the presence of FN. In addition, FN increased RhoA and Rho kinase activation, which were completely blocked by PP2, FAK small interfering RNA (siRNA), caveolin-1 siRNA, or the caveolar disruptor methyl-β-cyclodextrin (MβCD). FN also increased phosphorylation of Akt and ERK 1/2, which were significantly blocked by either FAK siRNA, caveolin-1 siRNA, MβCD, GGTI-286 (RhoA inhibitor), or Y-27632 (Rho kinase inhibitor). FN-induced increase of protooncogenes (c-fos, c-myc, and c-Jun) and cell-cycle regulatory proteins (cyclin D1/CDK4 and cyclin E/CDK2) expression levels were attenuated by FAK siRNA or caveolin-1 siRNA. Furthermore, inhibition of each pathway such as integrin β1, Src, FAK, caveolin-1, RhoA, Akt, and ERK 1/2 blocked FN-induced [3H]-thymidine incorporation. We conclude that FN stimulates mouse ES cell proliferation via RhoA-PI3K/Akt-ERK 1/2 pathway through caveolin-1 phosphorylation. © 2010 Wiley-Liss, Inc.

Huh J.W.,Sungkyunkwan University | Lee J.H.,Chonnam National University | Kim H.R.,Chonnam National University | Kim Y.J.,Chonnam National University
American Journal of Surgery | Year: 2013

Background This study was designed to evaluate the prognostic significance of the positivity of lymphovascular (LVI) and perineural invasion (PNI) in patients with locally advanced colorectal cancer. Methods From January 1999 to December 2009, 1,437 consecutive patients who underwent curative surgery for stage II or III colorectal cancer were analyzed. Patients were then categorized into 4 groups: LVI-/PNI- (n = 850), LVI+ only (n = 178), PNI+ only (n = 271), and LVI+/PNI+ (n = 138). Results With a median follow-up period of 56 months, the 5-year overall survival rates of patients with LVI-/PNI-, LVI+ only, PNI+ only, and LVI+/PNI+ were 82%, 73%, 71%, and 56%, respectively (P <.001), and the 5-year disease-free survival rates of patients with LVI-/PNI-, LVI+ only, PNI+ only, and LVI+/PNI+ were 80%, 70%, 65%, and 46%, respectively (P <.001). In multivariate analysis, LVI+/PNI+ was an independent prognostic factor for both overall survival (P <.001) and disease-free survival (P <.001). Conclusions Positivity of both LVI and PNI is a strong predictor of overall and disease-free survival in patients with stages II and III colorectal cancer. © 2013 Elsevier Inc. All rights reserved.

Sung M.-S.,Chonnam National University | Yoon J.-H.,Occupational Lung Disease Institute | Park S.-W.,Chonnam National University
Journal of Glaucoma | Year: 2014

Purpose: To evaluate the diagnostic validity of macular ganglion cell-inner plexiform layer (mGCIPL) thickness deviation map algorithm using Cirrus high definition-optical coherence tomography to discriminate between normal controls and patients with preperimetric or early glaucoma.Patients and Methods: Seventy-two normal controls, 37 patients with preperimetric glaucoma and 70 patients with early glaucoma were enrolled. mGCIPL thickness and peripapillary retinal nerve fiber layer (pRNFL) thickness were measured by Cirrus high definition-optical coherence tomography. Areas showing abnormal color coding were obtained by customized Image J software calculating the number of abnormal superpixels at 1% and 5% level in each deviation map of measurements (GCIPL-DM1, GCIPLDM5, RNFL-DM1, RNFL-DM5). The area under the receiver operating characteristic curve (AROC) of each parameter was calculated to provide diagnostic ability between normal controls and patients with preperimetric or early glaucoma.Results: AROCs of the deviation map algorithms were higher than those of other parameters. Parameter with the best AROC was the GCIPL-DM5 (0.920 and 0.968) in both preperimetric and early glaucoma. The sensitivities of the GCIPL-DM5 at 80% and 95% specificities were 92% and 68% in preperimetric glaucoma and 98% and 90% in early glaucoma, respectively. Pairwise comparisons between AROCs of parameters from deviation map algorithms did not show statistically significant differences.Conclusions: mGCIPL thickness deviation map showed good diagnostic ability in detecting preperimetric and early glaucoma, and it was comparable with pRNFL thickness deviation map. Our findings suggest that it can be an important parameter in detecting subtle glaucomatous structural change. Copyright © 2013 by Lippincott Williams & Wilkins.

Noh H.-R.,Chonnam National University
Optics Express | Year: 2012

We present a theoretical study of lineshape in polarization spectroscopy for the 6S1/2-6P3/2-7S1/2 transition line in cesium atoms. A circularly polarized pump beam is tuned either to the lower or the upper transition line, while a linearly polarized probe beam is tuned to the other transition line. The polarization rotation of the probe beam is accurately calculated using a semi-classical density-matrix formalism taking into account all relaxation processes. © 2012 Optical Society of America.

Byeon Y.,Chonnam National University | Lee H.Y.,Chonnam National University | Back K.,Chonnam National University
Journal of Pineal Research | Year: 2015

Serotonin N-acetyltransferase (SNAT), the penultimate enzyme in melatonin biosynthesis, catalyzes the conversion of serotonin into N-acetylserotonin. Plant SNAT is localized in chloroplasts. To test SNAT localization effects on melatonin synthesis, we generated transgenic rice plants overexpressing a sheep (Ovis aries) SNAT (OaSNAT) in their chloroplasts and compared melatonin biosynthesis with that of transgenic rice plants overexpressing OaSNAT in their cytoplasm. To localize the OaSNAT in chloroplasts, we used a chloroplast targeting sequence (CTS) from tobacco protoporphyrinogen IX oxidase (PPO), which expresses in chloroplasts. The purified recombinant CTS:OaSNAT fusion protein was enzymatically functional and localized in chloroplasts as confirmed by confocal microscopic analysis. The chloroplast-targeted CTS:OaSNAT lines and cytoplasm-expressed OaSNAT lines had similarly high SNAT enzyme activities. However, after cadmium and butafenacil treatments, melatonin production in rice leaves was severalfold lower in the CTS:OaSNAT lines than in the OaSNAT lines. Notably, enhanced SNAT enzyme activity was not directly proportional to the production of N-acetylserotonin, melatonin, or 2-hydroxymelatonin, suggesting that plant SNAT has a role in the homeostatic regulation of melatonin rather than in accelerating melatonin synthesis. © 2015 John Wiley and Sons A/S. Published by John Wiley and Sons Ltd.

Sohn I.S.,Chonnam National University | Unithrattil S.,Chonnam National University | Im W.B.,Chonnam National University
ACS Applied Materials and Interfaces | Year: 2014

Application of quantum dots as a color converter in white light-emitting diodes (WLEDs) has been highly restrained because of its lower stability under the operating conditions of LEDs. The feasibility of using quantum dots in WLEDs has been studied and demonstrated by developing a non-conventional packing technique. Multiple core shell CuInS2/ZnS quantum dots were coated by silica, and the silica-coated quantum dots were dispersed in ethoxylated trimethylolpropane triacrylate to form a color conversion film. This along with phosphor in a glass plate made of Y3Al5O 12:Ce3+ phosphor was stacked in different configurations, and its effect on color rendering of WLEDs was studied. In addition, the configuration developed here protects the color converter from thermal strain and moisture. © 2014 American Chemical Society.

Mali S.S.,Chonnam National University | Patil P.S.,Shivaji University | Hong C.K.,Chonnam National University
ACS Applied Materials and Interfaces | Year: 2014

In the present investigation, kesterite Cu2ZnSnS4 (CZTS) nanofibers were obtained by electrospinning process using polyvinylpyrrolidone (PVP) and cellulose acetate (CA) solvent separately. The synthesized CZTS nanofibers were characterized using thermogravimetric analysis (TGA), optical absorption, X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FESEM), micro-Raman spectroscopy, high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS). Our results showed that the PVP synthesized CZTS nanofibers are a single crystalline while CA assisted CZTS nanofibers are polycrystalline in nature. The optical properties demonstrated that the prepared nanofibers have strong absorption in 300-550 nm range with band gap energy of 1.5 eV. The X-ray and micro-Raman analysis revealed that synthesised nanofibers showing pure phase kesterite CZTS. Further the synthesized CZTS nanofibers were used as counter electrodes for dye-sensitized solar cells (DSSCs). Our results indicate that, PVP-CZTS and CA-CZTS counter electrode based DSSC shows 3.10% and 3.90% respectively. The detailed interfaces of these counter electrodes and DSSCs were analyzed by electrochemical impedance spectroscopic (EIS) measurements for analysis of such high power conversion efficiency. The present study will be helpful for alternative counter electrode for Pt counter electrodes in DSSCs application. We believe that our synthetic method will be helpful for low-cost and efficient thin film photovoltaic technology. © 2014 American Chemical Society.

Park E.-J.,Chonnam National University | Jhon D.-Y.,Chonnam National University
LWT - Food Science and Technology | Year: 2010

This study was undertaken to evaluate the functional properties of two of the most popular species of edible bamboo shoots in Korea (Phyllostachys pubescens and Phyllostachys nigra). Powdered bamboo shoots were extracted with methanol and an aqueous suspension of the obtained methanol extract was partitioned successively with chloroform, ethyl acetate, and butanol, leaving a residual water extract. All obtained extracts were evaluated for their antioxidant capacity and antimicrobial activity, angiotensin converting enzyme (ACE) inhibition activity, and ascorbic acid and phenolic compound content. Methanol and water fractions showed a particularly high ascorbic acid contents. The ethyl acetate fraction contained a high concentration of phenolic compounds. Among all extracts, the ethyl acetate and butanol fractions showed particularly high antioxidant activity. Methanol extract had a significantly higher ACE inhibitory activity than other extracts. None of the extracts inhibited the tested bacteria. © 2009 Elsevier Ltd. All rights reserved.

Lim J.,Korea University | Choi H.-S.,Chonnam National University | Choi H.J.,Korea University
Journal of Neurochemistry | Year: 2015

The orphan nuclear receptor estrogen-related receptor gamma (ERRγ) is highly expressed in the nervous system during embryogenesis and in adult brains, but its physiological role in neuronal development remains unknown. In this study, we evaluated the relevance of ERRγ in regulating dopaminergic (DAergic) phenotype and the corresponding signaling pathway. We used retinoic acid (RA) to differentiate human neuroblastoma SH-SY5Y cells. RA induced neurite outgrowth of SH-SY5Y cells with an increase in DAergic neuron-like properties, including up-regulation of tyrosine hydroxylase, dopamine transporter, and vesicular monoamine transporter 2. ERRγ, but not ERRα, was up-regulated by RA, and participated in RA effect on SH-SY5Y cells. ERRγ over-expression enhanced mature DAergic neuronal phenotype with neurite outgrowth as with RA treatment; and RA-induced increase in DAergic phenotype was attenuated by silencing ERRγ expression. ERRγ appears to have a crucial role in morphological and functional regulation of cells that is selective for DAergic neurons. Polo-like kinase 2 was up-regulated in ERRγ-over-expressing SH-SY5Y cells, which was involved in phosphorylation of glycogen synthase kinase 3β and resulting downstream activation of nuclear factor of activated T cells. The likely involvement of ERRγ in regulating the DAergic neuronal phenotype makes this orphan nuclear receptor a novel target for understanding DAergic neuronal differentiation. © 2015 International Society for Neurochemistry.

Unithrattil S.,Chonnam National University | Lee K.H.,Chonnam National University | Im W.B.,Chonnam National University
Journal of the American Ceramic Society | Year: 2014

The Eu2+, M-codoped(M = Ce3+, Mn2+) phosphor powders were prepared by a solid-state reaction. The addition of Ce3+ in the Eu2+ sites in partially nitridated bredigite-structure phosphor(CMSN) remarkably enhances the luminescent intensity by ~180% through sensitized luminescence. Dual band emission was observed for Eu, Mn-codoped CMSN through energy transfer from Eu2+ to Mn 2+. Ce3+-Eu2+ and Eu2+-Mn 2+ energy-transfer mechanism was investigated through decay profile analysis using Inokuti-Hirayama model and energy-transfer parameters are determined. Interaction mechanism was identified as dipole-dipole interaction. In addition, phosphor in glass plates was prepared using the phosphor and its feasibility in white LED application was studied and is presented. © 2013 The American Ceramic Society.

Lee J.-W.,Chonnam National University | Jeffries T.W.,U.S. Department of Agriculture
Bioresource Technology | Year: 2011

Dicarboxylic organic acids have properties that differ from those of sulfuric acid during hydrolysis of lignocellulose. To investigate the effects of different acid catalysts on the hydrolysis and degradation of biomass compounds over a range of thermochemical pretreatments, maleic, oxalic and sulfuric acids were each used at the same combined severity factor (CSF) values during hydrolysis. Xylose and glucose concentrations in hydrolysates were highest with maleic acid. Oxalic acid gave the next highest followed by sulfuric acid. This ranking was particularly true at low CSF values. The concentrations of glucose and xylose increased with oxalic and sulfuric acid pretreatments as the CSF increased, but they never attained the levels observed with maleic acid. Among sulfuric, oxalic and maleic acid treatments, the amount of xylose released as xylooligosaccharide was highest with sulfuric acid. The fraction of xylooligosaccharide was lowest with the maleic acid and the oligosaccharide fraction with oxalic acid fell in between. Furfural and hydroxymethyl furfural levels were also highest with maleic acid. In subsequent fermentations with pretreated biomass, the ethanol concentration was maximal at 19.2. g/l at CSF 1.9 when maleic acid was used as the pretreatment catalyst. This corresponded to an ethanol volumetric production rate of 0.27. g ethanol/l per h. This was the same condition showing the highest xylose production in following pretreatment with various acid catalysts. These findings suggest that maleic and oxalic dicarboxylic acids degrade hemicelluloses more efficiently than does sulfuric acid. © 2011.

Park K.H.,Chonnam National University
CIN - Computers Informatics Nursing | Year: 2016

The purpose of this study was to develop a Web video designed to promote regular shoulder joint exercise on a continuous basis among patients with shoulder joint disease. This is a methodological research. A shoulder joint exercise video was developed through the five stages of the ADDIE model: analysis, design, development, implementation, and evaluation. The video demonstrates exercises that stretch and strengthen the joints and muscles of the shoulders. Stretching exercises include the pendulum, forward elevation, outer rotation, crossover arm stretch, inner rotation, and the sleeper; strengthening exercises include dumbbell exercises, a chair exercise, wall push-ups, and rowing. This Web exercise video can be used as an educational resource for preventing shoulder joint diseases by middle-aged and elderly people and those seeking to restore shoulder joint function damaged by shoulder joint diseases.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.

Park M.-J.,Chonnam National University | Kim D.-I.,Chonnam National University | Choi J.-H.,Chonnam National University | Heo Y.-R.,Chonnam National University | Park S.-H.,Chonnam National University
Cellular Signalling | Year: 2015

Irisin is a newly identified myokine related to exercise and the browning of white fat. Recently, it was reported that irisin serum levels are associated with intrahepatic triglyceride content, suggesting that it might have an important role in the liver. The aim of this study was to determine the role of irisin in hepatocytes. Specifically, the effect of recombinant irisin on palmitic acid (PA)-induced lipogenesis and its related signal pathways were examined in AML12 cells and mouse primary hepatocytes. In the present study, we observed the presence of irisin inside the cells in response to the treatment of recombinant irisin by flow cytometry and cell imaging technique. Recombinant irisin significantly inhibited the PA-induced increase in lipogenic markers ACC and FAS at the mRNA and protein levels, and prevented the PA-induced lipid accumulation in hepatocytes. Additionally, irisin inhibited the PA-induced increase in the expression, nuclear localization, and transcriptional activities of the master regulators of lipogenesis (LXRα and SREBP-1c). Moreover, irisin attenuated PA-induced oxidative stress, which was confirmed by measuring the expression of inflammatory markers (NFκB, COX-2, p38 MAPK, TNF, IL-6) and superoxide indicator (dihydroethidium). The preventive effects of irisin against lipogenesis and oxidative stress were mediated by the inhibition of protein arginine methyltransferase-3 (PRMT3). These findings suggested that irisin might have a beneficial role in the prevention of hepatic steatosis by altering the expression of lipogenic genes and attenuating oxidative stress in a PRMT3 dependent manner. © 2015 Elsevier Inc.

Jeong S.-Y.,Chonnam National University | Lee J.-W.,Chonnam National University
Bioresource Technology | Year: 2016

Sequential Fenton oxidation (FO) and hydrothermal treatment were performed to improve the effect of pretreatment and enzymatic hydrolysis of mixed hardwood. The molar ratio of the Fenton reagent (FeSO4·7H2O and H2O2) was 1:25, and the reaction time was 96h. During the reaction, little or no weight loss of biomass was observed. The concentration of Fe2+ was determined and was found to increase continuously during FO. Hydrothermal treatment at 190-210°C for 10-80min was performed following FO. Sequential FO and hydrothermal treatment showed positive effects on pretreatment and enzymatic hydrolysis. Xylose concentration in the hydrolysate was as high as 14.16g/L when FO-treated biomass was treated at 190°C, while its concentration in the raw material was 3.72g/L. After 96h of enzymatic hydrolysis, cellulose conversion in the biomass obtained following sequential treatment was 69.58-79.54%. In contrast, the conversion in the raw material (without FO) was 64.41-67.92%. © 2015 Elsevier Ltd.

Kim J.Y.,Chonnam National University | Lee Y.C.,Chonnam National University | Kim C.,Chonnam National University
Journal of Biological Chemistry | Year: 2010

The fate of stem cells is intricately regulated by numerous extrinsic and intrinsic factors that promote maintenance or differentiation. The RNA-binding translational repressor Pumilio (Pum) in conjunction with Nanos (Nos) is required for self-renewal, whereas Bam (bag-of-marbles) and Bgcn (benign gonial cell neoplasm) promote differentiation of germ line stem cells in the Drosophila ovary. Genetic analysis suggests that Bam and Bgcn antagonize Pum/Nos function to promote differentiation; however, the molecular basis of this epistatic relationship is currently unknown. Here, we show that Bam and Bgcn inhibit Pum function through direct binding. We identified a ternary complex involving Bam, Bgcn, and Pum in which Bam, but not Bgcn, directly interacts with Pum, and this interaction is greatly increased by the presence of Bgcn. In a heterologous reporter assay to monitor Pum activity, Bam, but not Bgcn, inhibits Pum activity. Notably, the N-terminal region of Pum, which lacks the C-terminal RNA-binding Puf domain, mediates both the ternary protein interaction and the Bam inhibition of Pum function. These studies suggest that, in cystoblasts, Bam and Bgcn may directly inhibit Pum/Nos activity to promote differentiation of germ line stem cells. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc.

Liu Z.,Chonnam National University | Yoon G.,Korea Institute of Science and Technology | Cheon S.H.,Chonnam National University
Tetrahedron | Year: 2010

The absolute configuration of (-)-licochalcone E (1) was determined to be (S) via the first enantioselective total synthesis of the compound. The chirality in (S)-(-)-licochalcone E (1) was installed by asymmetric methylation of the Evans' oxazolidinone derivatives. © 2010 Elsevier Ltd. All rights reserved.

Suh H.N.,Chonnam National University | Han H.J.,Chonnam National University
American Journal of Physiology - Cell Physiology | Year: 2010

Laminin is the first extracellular matrix (ECM) component to be expressed in the developing mammalian embryo. However, the roles of laminin or the related signal pathways are not well known in mouse embryonic stem cells (mESCs). Presently, we examined the effect of laminin on mESC migration. Laminin (10 μg/ml) decreased cell aggregation, whereas migration was increased. Laminin bound α6β1 integrin and laminin receptor 1 (LR1), decreasing their mRNA levels. Laminin increased focal adhesion kinase (FAK) and paxillin phosphorylation, cAMP intracellular concentration, and the protein levels of exchange factor directly activated by cAMP (Epac1) and Rap1. These increases were completely blocked by α6β1 integrin and LR1 neutralizing antibody, indicating that laminin-bound LR1 assists laminin-induced α6β1 integrin activity and initiates signal. As a downstream signal molecule, laminin activated small G protein such as Rac1/cdc42 and its effector protein p21-activated kinase (PAK). Subsequently, laminin stimulated E-cadherin complex disruption. Inhibition of each pathway such as those for α6β1 integrin and LR1, FAK, Rap1, and PAK1 blocked laminin-induced migration. We conclude that laminin binds both α6β1 integrin and LR1 and induces signaling FAK/paxillin and cAMP/Epac1/Rap1. These signaling merge at Rac1/cdc42 subsequently activate PAK1. Activated PAK1 enhances E-cadherin complex disruption and finally increases mESCs migration. Copyright © 2010 the American Physiological Society.

Lee H.-J.,Chonnam National University | Hong M.-K.,Korea Environment Corporation | Moon S.-H.,Gwangju Institute of Science and Technology
Desalination | Year: 2012

Interests on the polarity reversal have increased to prevent or minimize membrane fouling and scaling during the operation of electromembrane processes. In this study, the influence of the operation conditions on the process efficiency was investigated in the electrodeionization reversal (EDIR) system with an electrodeionization with the polarity reversal. The removal efficiencies of divalent cations (Mg 2+ and Ca 2+) kept high value without scale formation on the membrane surface. Through the EDIR operation, the process performance was affected by polarity reversal periods, and the operating polarity reversal period was determined to 40min or shorter in this study.In the long term EDIR experiments with different cation exchange membranes, the homogeneous membranes showed marginally higher removal efficiency compared to the heterogeneous membrane. The scale powders and the surface of scaled membrane were analyzed using electron microscopes and it was observed that the scales formed as carbonate of divalent cations. The EDIR results showed the feasibility of the EDIR system for use in water softening process without significant scale formation even in a relatively high concentration. © 2011 Elsevier B.V..

Kang W.D.,Chonnam National University | Choi H.S.,Chonnam National University | Kim S.M.,Chonnam National University
Gynecologic Oncology | Year: 2010

Objectives: The aim of this study was to ascertain whether serum CA125 level is predictive of disease progression in patients with high-risk, early stage (stage IA/B grade 3, stage IC any grade, stage I clear cell, or stage II) epithelial ovarian cancer who have achieved a complete response to chemotherapy. Methods: Between January 1998 and April 2004, we reviewed the records of 95 patients with high-risk, early stage epithelial ovarian cancer who had elevated CA125 levels at the time of diagnosis and were complete responders after 6 cycles of adjuvant paclitaxel/carboplatin chemotherapy. A receiver operating characteristic curve was used to determine the most useful CA125 level in predicting disease progression and Cox proportional hazards models adjusted for covariates were used for analyses. Results: The 5-year progression-free survival (PFS) was 70.5%. The optimal cutoff point of CA125 after completing adjuvant chemotherapy to predict disease progression was 12 U/mL (sensitivity, 71.4%; specificity, 82.1%). On multivariate analysis, CA125 level > 12 U/mL after completing adjuvant chemotherapy was an independent prognostic factor predictive for disease progression. The risk of recurrence was higher for CA125 level > 12 U/mL (hazards ratio = 10.567; P < 0.001). The 5-year PFS rate for patients with CA125 level ≤ 12 U/mL was 83.3%, which was higher than a PFS of 37.5% for CA125 > 12 U/mL (P < 0.001). Conclusions: CA125 level after 6 cycles of adjuvant chemotherapy is a strong independent prognostic factor for high-risk, early stage epithelial ovarian cancer after achieving a complete response. © 2009 Elsevier Inc. All rights reserved.

Kim Y.-W.,Chonnam National University | Kim D.-H.,Chonnam National University
Korean Journal of Chemical Engineering | Year: 2012

Ozone (O 3) was employed as an oxygen source for the atomic layer deposition (ALD) of titanium dioxide (TiO 2) based on tetrakis-dimethyl-amido titanium (TDMAT). The effects of deposition temperature and O 3 feeding time on the film growth kinetics and physical/chemical properties of the TiO 2 films were investigated. Film growth was possible at as low as 75 °C, and the growth rate (thickness/cycles) of TiO 2 was minimally affected by varying the temperatures at 150-225 °C. Moreover, saturated growth behavior on the O 3 feeding time was observed at longer than 0.5 s. Higher temperatures tend to provide films with lower levels of carbon impurities. The film thickness increased linearly as the number of cycles increased. With thicker films and at higher deposition temperatures, surface roughening tended to increase. The as-deposited films were amorphous regardless of the substrate temperatures and there was no change of crystal phase even after annealing at temperatures of 400-600 °C. The films deposited in 0.5 mm holes with an aspect ratio of 3: 1 showed an excellent conformality. © 2012 Korean Institute of Chemical Engineers, Seoul, Korea.

Lee H.S.,Chonnam National University | Kim K.H.,Chonnam National University | Kim S.H.,Chonnam National University | Kim J.N.,Chonnam National University
Advanced Synthesis and Catalysis | Year: 2012

An efficient synthesis of tetrasubstituted olefins was achieved via a palladium-catalyzed, chelation-assisted oxidative Heck arylation protocol from trisubstituted olefins bearing a tether with a directing group in a completely stereo- and regioselective manner. The stereo- and regioselectivity as well as excellent yields of tetrasubstituted olefins originated from the stabilization of a palladium intermediate by chelation between the palladium center and a directing group. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nguyen-Pham T.-N.,Chonnam National University | Lee Y.-K.,Chonnam National University | Kim H.-J.,Chonnam National University | Lee J.-J.,Chonnam National University
Clinical and Developmental Immunology | Year: 2012

Multiple myeloma (MM) is a good target disease in which one can apply cellular immunotherapy, which is based on the graft-versus-myeloma effect. This role of immune effector cells provides the framework for the development of immune-based therapeutic options that use antigen-presenting cells (APCs) with increased potency, such as dendritic cells (DCs), in MM. Current isolated idiotype (Id), myeloma cell lysates, myeloma dying cells, DC-myeloma hybrids, or DC transfected with tumor-derived RNA has been used for immunotherapy with DCs. Immunological inhibitory cytokines, such as TGF-β, IL-10, IL-6 and VEGF, which are produced from myeloma cells, can modulate antitumor host immune response, including the abrogation of DC function, by constitutive activation of STAT3. Therefore, even the immune responses have been observed in clinical trials, the clinical response was rarely improved following DC vaccinations in MM patients. We are going to discuss how to improve the efficacy of DC vaccination in MM. © Copyright 2012 Thanh-Nhan Nguyen-Pham et al.

Cao X.,Chonnam National University | Jin F.,Xi'an Jiaotong University | Jeon I.,Chonnam National University
NDT and E International | Year: 2011

To investigate the propagation behavior of Lamb waves in a thermal stress relaxation type functionally graded material (FGM) plate with material parameters that vary continuously along the thickness, the power series technique, which has been proved to have good convergence and high precision, is employed for theoretical derivations. The influence of the gradient coefficients of FGM on the dispersion curves is illustrated. The numerical results also reveal differences between the properties of Lamb wave propagation in the FGM plate and the corresponding properties in a homogenous plate. In terms of results, we find that both the normal and anomalous dispersions exist in the first and the second modes of the Lamb wave that propagates in the FGM plate, while only the anomalous dispersion is in the first mode and only the normal dispersion is in the second mode for the homogenous plate. The wave structure is asymmetric due to the asymmetric properties of the material. The dominance of in-plane and out-plane displacements is different between the metal-rich and ceramic-rich surfaces. All these results give theoretical guidance not only for experimental measurement of material properties but also for nondestructive evaluation using an ultrasonic wave generation device. © 2010 Elsevier Ltd. All rights reserved.

Noh M.Y.,Chonnam National University | Muthukrishnan S.,Kansas State University | Kramer K.J.,Kansas State University | Arakane Y.,Chonnam National University
PLoS genetics | Year: 2015

Insect cuticle is composed mainly of structural proteins and the polysaccharide chitin. The CPR family is the largest family of cuticle proteins (CPs), which can be further divided into three subgroups based on the presence of one of the three presumptive chitin-binding sequence motifs denoted as Rebers-Riddiford (R&R) consensus sequence motifs RR-1, RR-2 and RR-3. The TcCPR27 protein containing the RR-2 motif is one of the most abundant CPs present both in the horizontal laminae and in vertical pore canals in the procuticle of rigid cuticle found in the elytron of the red flour beetle, Tribolium castaneum. Depletion of TcCPR27 by RNA interference (RNAi) causes both unorganized laminae and pore canals, resulting in malformation and weakening of the elytron. In this study, we investigated the function(s) of another CP, TcCPR4, which contains the RR-1 motif and is easily extractable from elytra after RNAi to deplete the level of TcCPR27. Transcript levels of the TcCPR4 gene are dramatically increased in 3 d-old pupae when adult cuticle synthesis begins. Immunohistochemical studies revealed that TcCPR4 protein is present in the rigid cuticles of the dorsal elytron, ventral abdomen and leg but not in the flexible cuticles of the hindwing and dorsal abdomen of adult T. castaneum. Immunogold labeling and transmission electron microscopic analyses revealed that TcCPR4 is predominantly localized in pore canals and regions around the apical plasma membrane protrusions into the procuticle of rigid adult cuticles. RNAi for TcCPR4 resulted in an abnormal shape of the pore canals with amorphous pore canal fibers (PCFs) in their lumen. These results support the hypothesis that TcCPR4 is required for achieving proper morphology of the vertical pore canals and PCFs that contribute to the assembly of a cuticle that is both lightweight and rigid.

Kim M.,Gwangju Institute of Science and Technology | Kim S.E.,Chonnam National University | Kang S.S.,Chonnam National University | Kim Y.H.,Gwangju Institute of Science and Technology | Tae G.,Gwangju Institute of Science and Technology
Biomaterials | Year: 2011

Partial-thickness cartilage defects, with no subchondral bone injury, do not repair spontaneously, thus there is no clinically effective treatment for these lesions. Although the autologous chondrocyte transplantation (ACT) is one of the promising approaches for cartilage repair, it requires in vitro cell expansion to get sufficient cells, but chondrocytes lose their chondrogenic phenotype during expansion by monolayer culture, leading to de-differentiation. In this study, a heparin-based hydrogel was evaluated and optimized to induce cartilage regeneration with de-differentiated chondrocytes. First, re-differentiation of de-differentiated chondrocytes encapsulated in heparin-based hydrogels was characterized in vitro with various polymer concentrations (from 3 to 20 wt.%). Even under a normal cell culture condition (no growth factors or chondrogenic components), efficient re-differentiation of cells was observed with the optimum at 10 wt.% hydrogel, showing the complete re-differentiation within a week. Efficient re-differentiation and cartilage formation of de-differentiated cell/hydrogel construct were also confirmed in vivo by subcutaneous implantation on the back of nude mice. Finally, excellent cartilage regeneration and good integration with surrounding, similar to natural cartilage, was also observed by delivering de-differentiated chondrocytes using the heparin-based hydrogel in partial-thickness defects of rabbit knees whereas no healing was observed for the control defects. These results demonstrate that the heparin-based hydrogel is very efficient for re-differentiation of expanded chondrocytes and cartilage regeneration without using any exogenous inducing factors, thus it could serve as an injectable cell-carrier and scaffold for cartilage repair. Excellent chondrogenic nature of the heparin-based hydrogel might be associated with the hydrogel characteristic that can secure endogenous growth factors secreted from chondrocytes, which then can promote the chondrogenesis, as suggested by the detection of TGF- β1 in both in vitro and in vivo cell/hydrogel constructs. © 2011 Elsevier Ltd.

Yang Y.,Chongqing University of Technology | Kang B.-S.,Chonnam National University
Optics and Lasers in Engineering | Year: 2011

A digital particle holographic system for measurements of spray fields is presented. A double exposure hologram recording system with a synchronization system for time control is established, resulting in digital holograms that can be quickly recorded. To process recorded holograms, the correlation coefficient method is used for focal plane determination of particles. To remove noise and improve the quality of holograms and reconstructed images, a Wiener filter is adopted. The two-threshold and image segmentation methods are used for binary image transformation. For particle pairing, the match probability method is adopted. The proposed system is applied to a spray field, and three-dimensional velocities and sizes of spray droplets are measured. Measurement results from the digital holographic system are compared to those made by laser instruments, which prove the feasibility of the proposed in-line digital particle holographic system as a good measurement tool for spray droplets. © 2011 Elsevier Ltd.

Mali S.S.,Chonnam National University | Kim H.,Chonnam National University | Patil P.S.,Shivaji University | Hong C.K.,Chonnam National University
Dalton Transactions | Year: 2013

In the present article, vertically aligned ZnO nanorod arrays were synthesized by an aqueous chemical growth (ACG) route on a fluoride doped tin oxide (FTO) coated glass substrate. These nanorods were further sensitized with cadmium sulfide (CdS) quantum dots (QDs) by a successive ionic layer adsorption and reaction (SILAR) technique. The synthesized CdS coated ZnO nanorods were characterized for their structural and morphological properties with X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscopy (FESEM). Finally, prepared CdS coated 1D ZnO photoelectrodes were tested for their photoelectrochemical performance. Our results show that the sample deposited after 40 SILAR cycles shows 5.61 mA cm-2 short current density (JSC) with η = 1.61% power conversion efficiency. © 2013 The Royal Society of Chemistry.

Ahmed M.S.,Chonnam National University | Jeong H.,Chonnam National University | You J.-M.,Chonnam National University | Jeon S.,Chonnam National University
Electrochimica Acta | Year: 2011

Cathodic dioxygen (O2) reduction was performed at a modified glassy carbon electrode (GCE) by single-walled carbon nanotubes (SWCNT)/Nafion® (NF) film with cobalt (II) tetra (2-amino-phenyl) porphyrin (CoTAPP) and palladium (Pd) nanoparticles incorporated and employed as doping agents. Both the electrochemical behavior of SWCNT with a P(CoTAPP)-Pd nanoparticle matrix and the electrocatalytic reduction of O2 were investigated using transmission electron microscopy (TEM), cyclic voltammetry (CV) and rotating ring-disk electrode (RRDE) techniques in 0.1 mol l -1 H2SO4 aqueous solutions. The electrocatalytic reduction of O2 at the SWCNT/NF/P(CoTAPP)-Pd composite film established a pathway of four-electron transfer reductions into H2O. Hydrodynamic voltammetry revealed that the modified electrode was catalyzed effectively by the four-electron transferred reduction of dioxygen into H2O with minimal generation of H2O2. The SWCNT/NF/P(CoTAPP)-Pd composite film showed a highly efficient electrocatalytic performance. P(CoTAPP)-Pd was an effective mediator for the reduction of dioxygen and was responsible for the enhanced catalytic activity. © 2011 Elsevier Ltd. All rights reserved.

Jung E.,Chonnam National University | Kim S.,Chung - Ang University | Kim Y.,Chonnam National University | Seo S.H.,Chung - Ang University | And 3 more authors.
Angewandte Chemie - International Edition | Year: 2011

Catching the couplings: A general and simple screening method for palladium-catalyzed coupling reactions of aryl iodides utilizes gold nanoparticles. This assay was successfully employed in several aminations, α-arylation of ketones, and decarboxylative couplings. 96 samples were screened in a few minutes. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pulse-amplitude modulated (PAM) fluorometry allows instantaneous estimates of photosynthetic rates, but may well produce variable measurements of photosynthetic activity depending on time of day, recent light history, internal fluctuations, and environmental variability. To investigate this, we compare estimates of diurnal variability in relative photosynthetic performance for the giant kelp, Macrocystis pyrifera (L.) C. Agardh, obtained from PAM fluorometry at three depths during 3 days characterized by different light conditions, and for two different blade ages. Sampling in the mid morning, late morning, early afternoon and late afternoon, we examined diurnal changes in relative photosynthetic performance in meristematic tissue and older blades occurring near the bottom, in the mid water, and at the water surface. Measures of maximum relative electron transport rates (rETRmax), minimum saturating irradiance (Ek), photosynthetic efficiency (α) and maximum quantum yield (Fv/Fm) show that giant kelp blades in the mid water and near the bottom exhibit little to no photosynthetic changes during the day. Near the surface, however, blades exhibit photosynthetic characteristics similar to light-adapted species in that they begin the day acclimated to low light, acclimate to increasing irradiance during the day, and end the day acclimated to low light. Consequently, while estimates of rETRmax were highest during the midday for all sample depths and days, they were also always highest near the surface for both old blades (112.16 ± 8.7, 98.6 ± 14.7, 70.16 ± 5.7) and meristematic tissue (109.0 ± 9.0, 86.9 ± 1.9, 59.2 ± 11.6, surface, mid water and bottom, respectively). Similar patterns were observed for Ek for both old blades (169.2 ± 5.4, 88.0 ± 11.2, 83.8 ± 5.2) and meristematic tissue (138.4 ± 11.5, 96.6 ± 4.69, 68.4 ± 10.6). In contrast, estimates of Fv/Fm were lowest near the surface during the midday for both old blades (0.6 ± 0.02, 0.73 ± 0.69, 0.75 ± 0.01) and meristematic tissue (0.58 ± 0.02, 0.69 ± 0.05, 0.74 ± 0.01, surface, mid water and bottom, respectively). These patterns coincided with similar patterns in ambient light, which was most variable and reached its greatest values near the surface during the midday. © 2009 Elsevier B.V. All rights reserved.

Choi Y.Y.,Chonnam National University
Korean Journal of Pediatrics | Year: 2014

While the survival of extremely premature infants with respiratory distress syndrome has increased due to advanced respiratory care in recent years, necrotizing enterocolitis (NEC) remains the leading cause of neonatal mortality and morbidity. NEC is more prevalent in lower gestational age and lower birth weight groups. It is characterized by various degrees of mucosal or transmural necrosis of the intestine. Its exact pathogenesis remains unclear, but prematurity, enteral feeding, bacterial products, and intestinal ischemia have all been shown to cause activation of the inflammatory cascade, which is known as the final common pathway of intestinal injury. Awareness of the risk factors for NEC; practices to reduce the risk, including early trophic feeding with breast milk and following the established feeding guidelines; and administration of probiotics have been shown to reduce the incidence of NEC. Despite advancements in the knowledge and understanding of the pathophysiology of NEC, there is currently no universal prevention measure for this serious and often fatal disease. Therefore, new potential techniques to detect early biomarkers or factors specific to intestinal inflammation, as well as further strategies to prevent the activation of the inflammatory cascade, which is important for disease progression, should be investigated. © 2014 by The Korean Pediatric Society.

You J.-M.,Chonnam National University | Jeon S.,Chonnam National University
Electrochimica Acta | Year: 2011

An NADH biosensor based on MWCNTs-Pd nanoparticles and polymerized 3,4-ethylenedioxypyrrole (PEDOP) was developed and characterized. PEDOP/MWCNTs-Pd/GCE was prepared quickly and simply and showed improved sensitivity to NADH. Comparable results were obtained by cyclic voltammetric (CV) and amperometric methods for NADH determination. The amperometric method gave short response times, and linear regression was observed at concentrations below 1.0 mM. The proposed NADH biosensor exhibited a wide linear response range of 1 μM-13 mM during amperometric testing using an applied potential of 0.42 V, with a low detection limit of 0.18 μM (S/N = 3). The sensor demonstrated fast responses and good stability. © 2011 Elsevier Ltd. All Rights Reserved.

Kwon Y.-S.,Chonnam National University | Koh W.-J.,Sungkyunkwan University
Expert Opinion on Investigational Drugs | Year: 2016

Introduction: Tuberculosis (TB) is a major global health concern. And while there are treatments already on the market, there is a demand for new drugs that are effective and safe against Mycobacterium tuberculosis, which reduce the number of drugs and the duration of treatment in both drug-susceptible TB and multidrug-resistant TB (MDR-TB).Area covered: This review covers promising novel investigational TB drugs that are currently under development. Specifically, the authors review the efficacy of novel agents for the treatment of TB in preclinical, phase I and phase II clinical trials. The authors also review the safety and tolerability profiles of these drugs.Expert opinion: Bedaquiline and delamanid are the most promising novel drugs for the treatment of MDR-TB, each having high efficacy and tolerability. However, the best regimen for achieving better outcomes and reducing adverse drug reactions remains to be determined, with safety concerns regarding cardiac events due to QT prolongation still to be addressed. Pretomanid is a novel drug that potentially shortens the duration of treatment in both drug-susceptible and drug-resistant TB in combination with moxifloxacin and pyrazinamide. Linezolid shows marked efficacy in the treatment of MDR-TB and extensively drug-resistant TB (XDR-TB), but the drug is known to cause significant adverse drug reactions, including peripheral neuropathy, optic neuropathy and myelosuppression. These adverse reactions must be considered prior to prescribing long-term usage of this drug. © 2015 Taylor and Francis.

Kim H.-W.,Yonsei University | Gupta S.,Bhilai Institute of Technology | Koh J.,Chonnam National University
Information and Management | Year: 2011

Some social networking community service providers have earned revenue by selling digital items to their community members. We examined SNC member decisions to purchase digital items based on customer value theory. Six factors were extracted from three dimensions of customer value: functional, social, and emotional value. Our findings indicated that the effects of value on member purchase intentions were significant in terms of the emotional and social dimensions. Our results should help SNC providers by improving their sales of digital items. © 2011 Elsevier B.V. All rights reserved.

Yoon W.,Chonnam National University | Jung M.Y.,Chonnam National University | Jung S.H.,Chonnam National University | Park M.S.,Chonnam National University | And 2 more authors.
Stroke | Year: 2013

BACKGROUND AND PURPOSE - : Subarachnoid hemorrhage (SAH) may appear on computerized tomography scans after mechanical thrombectomy for acute ischemic stroke. The incidence and prognosis of this observation remain unknown. We investigated the frequency and clinical consequences of SAH after treating acute ischemic stroke with a multimodal approach heavily weighted toward mechanical thrombectomy with Solitaire stent. METHODS - : Seventy-four consecutive patients with acute ischemic stroke underwent mechanical thrombectomy with a Solitaire stent as a first-line treatment. Nonenhanced computerized tomography scans were performed before, immediately after, and 24 hours after treatment to detect SAH. Clinical outcome was assessed after treatment, on day 1, at discharge, and at 3 months. Clinical and radiological data were compared between patients with and without SAH. RESULTS - : Twelve patients (16.2%) exhibited SAH associated with pure SAH (n=4) or mixed SAH and contrast extravasation (n=8). The SAH was located in the ipsilateral Sylvian fissure (n=11) or bilateral parietooccipital sulci (n=1). Patients with SAH had no periprocedural vessel perforations or arterial dissections and no postprocedural neurological deteriorations. Rescue angioplasty was performed more frequently in SAH group than in control group (33.3% vs 9.7%; P=0.05). Patients with SAH and those without had similar recanalization rates and clinical outcomes. CONCLUSIONS - : SAH on post-therapeutic computerized tomography scans were not uncommon after primary mechanical thrombectomy with a Solitaire stent, but they seemed to be benign. Rescue angioplasty and unidentified, small vessel ruptures due to mechanical stretch during stent retrieval might give rise to these lesions. © 2013 American Heart Association, Inc.

Wang X.-L.,Chongqing University of Technology | Oh I.-K.,Korea Advanced Institute of Science and Technology | Lee S.,Chonnam National University
Sensors and Actuators, B: Chemical | Year: 2010

Based on a crosslinked ionic networking membrane of sulfonated poly(arylenethioethersulfone) copolymer (SPTES) and poly(vinyl alcohol) (PVA), a novel biomimetic artificial muscle with electrically driven bending deformation was developed. Sulfonated endcapped poly(arylenethioethersulfone) copolymer (SPTES) was synthesized through direct copolymerization of sulfonated monomers and poly(vinyl alcohol) (PVA) was crosslinked with SPTES by the dehydration method. The crosslinking reaction and molecular interactions between PVA and SPTES were observed in the FT-IR spectra of the PVA/SPTES ionic networking membrane. In comparison with the Nafion membrane, the crosslinked PVA/SPTES membrane shows much higher proton conductivity and ionic exchangeable capacity that are main factors influencing the actuation performance. Electroactive PVA/SPTES actuators show much larger bending deformation under step inputs without straightening-back relaxation and harmonic responses under sinusoidal excitations in a wide frequency band. © 2010 Published by Elsevier B.V.

Kim C.H.,Chonnam National University | Huh J.W.,Sungkyunkwan University | Kim H.R.,Chonnam National University | Kim Y.J.,Chonnam National University
Annals of Surgery | Year: 2015

Background: Chest computed tomographic (CT) scans frequently detect indeterminate pulmonary nodules (IPNs) in patients with colorectal cancer. The discovery of such nodules creates a clinical dilemma. Purpose: This study was performed to identify clinical characteristics of IPNs and develop a predictive model to predict the risk of progression to pulmonary metastases in patients with colorectal cancer. Methods: We analyzed data from a prospectively collected database involving 1195 patients with colorectal carcinoma who underwent curative surgery between January 2008 and June 2010. A predictive model was constructed on the basis of the probability risk score and validated in 115 patients collected from a separate treatment period. Results: Of the 1195 patients who underwent a baseline staging chest computed tomography, 326 (27.2%) had IPNs. During a median follow-up of 26.7 months (interquartile range: 18.0-37.2), 74 (28.1%) showed pulmonary metastases. Five variables maintained prognostic significance after multivariate analysis: metachronous nodule, bilateral involvement, positive perineural invasion, increased number of positive lymph nodes, and rectal location of cancer. The 2-year progression-free survival rates for the very low-, low-, intermediate-, and high-risk groups were 96%, 82%, 46%, and 16%, respectively (P < 0.001), with a concordance index of 0.81 (95% confidence interval, 0.75-0.86). This model was validated in a separate patient set (P < 0.001), with a C-index of 0.83 (95% confidence interval, 0.77-0.88). Conclusions: A predictive model for progression of IPNs may be clinically useful in discriminating patientswhomight benefit from an aggressive surveillance program and early pulmonary metastasectomies. Copyright © 2014 Wolters Kluwer Health, Inc. All rights reserved.

Kang B.,Chonnam National University
Journal of Applied Fluid Mechanics | Year: 2016

This paper experimentally studied the dynamic behavior of a droplet impacting upon a liquid film, by investigating the effects of the droplet velocity and thickness of the liquid film on the impact behavior of the droplet. The formation of the crown, central jet, and disintegrating droplet from the central jet were visualized by time-delay photography. The time evolutions of the diameter and height of the crown and the height of the central jet were obtained, and the size of the disintegrating droplet from the central jet was measured. The crown diameter and the central jet height were mostly affected by the droplet velocity and the thickness of the liquid film, respectively, while the crown height was influenced by both the droplet velocity and the thickness of the liquid film. The diameter and height of the crown were higher for the case of the faster impacting droplet and thinner liquid film. On the other hand, the height of the central jet was higher for the case of the faster impacting droplet and thicker liquid film. The size of the disintegrating droplet from the central jet heavily depends on the velocity of the impacting droplet. Namely, a larger droplet is produced by a faster impacting droplet.

Ha K.,Chonnam National University
Zeitschrift fur Kristallographie - New Crystal Structures | Year: 2011

C 22H 20Cl 2N 2OPt, monoclinic, C12/c1 (no. 15), a = 9.4199(5) Å, b = 23.687(1) Å, c = 8.8435(5) Å, β = 101.257(1)°, V= 1935.3 Å 3, Z = 4, R gt(F) = 0.026, wR reg(F 2) = 0.072, T= 200 K. © by Oldenbourg Wissenschaftsverlag, München.

Ha K.,Chonnam National University
Acta Crystallographica Section E: Structure Reports Online | Year: 2011

The PdII ion in the title complex, [PdI2(C 14H10N4)], is four-coordinated in a slightly distorted square-planar environment by the two pyridine N atoms of the chelating 2,3-di-2-pyridyl-pyrazine (dpp) ligand and two iodide anions. In the crystal, the pyridine rings are considerably inclined to the least-squares plane of the PdI2N2 unit [maximum deviation = 0.090 (2) Å], making dihedral angles of 65.0 (2) and 66.6 (2)°. The pyrazine ring is perpendicular to the unit plane, with a dihedral angle of 89.9 (2)°. The complex molecules are connected by C - H⋯I hydrogen bonds, forming a helical chain along the b axis. © Kwang Ha 2011.

Ha K.,Chonnam National University
Acta Crystallographica Section E: Structure Reports Online | Year: 2011

The PdII ion in the title complex, [PdCl2(C 14H10N4)], has a slightly distorted square-planar environment defined by the two pyridine N atoms of the chelating 2,3-di-2-pyridylpyrazine ligand and two chloride anions. The pyridine rings are considerably inclined to the least-squares plane of the PdCl2N 2 unit [maximum deviation = 0.073 (1) Å], with dihedral angles of 64.19 (9) and 66.55 (9)°. The pyrazine ring is almost perpendicular to this plane and the dihedral angle is 88.2 (1)°. Two independent intermolecular C - H⋯Cl hydrogen bonds, both involving the same Cl atom as a hydrogen-bond acceptor, give rise to chains running along the a and b axes, generating a layer structure extending parallel to (001). molecules are stacked in columns along the a axis. Along the b axis, successive molecules stack in opposite directions. © Kwang Ha 2011.

Ha K.,Chonnam National University
Zeitschrift fur Kristallographie - New Crystal Structures | Year: 2011

C 10H 9Cl 4N 3Pt, monoclinic, P2 1/m (no. 11), a = 6.7195(6) Å, b = 14.014(1) Å, c = 7.6712(7) Å, β = 114.863(2)°, V= 655.4 Å 3, Z= 2, R gt(F) = 0.026, wR ref(F 2) = 0.052, T=200 K. © by Oldenbourg Wissenschaftsverlag, München.

Ha K.,Chonnam National University
Acta Crystallographica Section E: Structure Reports Online | Year: 2011

The MnII ion in the title complex, [MnBr2(C 18H12N6)], is five-coordinated in a distorted square-pyramidal geometry by three N atoms of the tridentate 2,4,6-tri-2-pyridyl-1,3,5-triazine (tptz) ligand and two bromide anions. In the crystal, the pyridyl rings coordinated to the Mn atom are inclined slightly to their carrier triazine ring [dihedral angles = 8.0 (3) and 7.5 (3)°], whereas the uncoordinated pyridyl ring is located approximately parallel to the triazine ring [dihedral angle = 3.7 (3)°]. The complexes are stacked in columns along the a axis and linked by intermolecular C-H⋯Br hydrogen bonds, forming chains. In the column, intermolecular π-π interactions between the six-membered rings are present, the shortest centroid-centroid distance being 3.750 (4) Å.

Ha K.,Chonnam National University
Zeitschrift fur Kristallographie - New Crystal Structures | Year: 2011

C 22H 18C 12N 2Pd, triclinic, P1̄ (no. 2), a = 7.1075(5) Å, b = 8.0015(6) Å, c = 9.6728(7) Å, α = 77.772(2)°, β = 89.032(2)°, γ = 68.724(1)°, V= 499.9 Å 3, Z = 1, R gt(F) = 0.039, wR ref(F 2) = 0.085, T= 200 K. © by Oldenbourg Wissenschaftsverlag, Münchcn.

Ha K.,Chonnam National University
Zeitschrift fur Kristallographie - New Crystal Structures | Year: 2011

C8H26Mn2N4O18S 2, monoclinic, P121/c1 (no. 14), a = 8.1522(5) Å, b = 11.6765(7) Å, c = 11.9942(7) Å, β = 91.667(1)°, V= 1141.2 Å3, Z= 2, Rgt(F) = 0.036, wRref(F 2) = 0.104, T= 200 K. © by Oldenbourg Wissenschaftsverlag, München.

Ha K.,Chonnam National University
Acta Crystallographica Section E: Structure Reports Online | Year: 2011

The Pt II ion in the title complex, [PtCl 2(C 14H 10N 4)], is four-coordinated in a distorted square-planar environment by two N atoms of a chelating 2,3-di-2-pyridyl- pyrazine ligand and two chloride anions. The pyridyl ring coordinated to the Pt II atom is inclined slightly to its carrier pyrazine ring [dihedral angle = 13.5 (1)°], whereas the uncoordinated pyridyl ring is inclined considerably to the pyrazine ring [dihedral angle = 54.3 (2)°]. The dihedral angle between the two pyridyl rings is 59.2 (2)°. In the crystal, the complexes are assembled through intermolecular C-H⋯N and C-H⋯Cl hydrogen bonds, forming a three-dimensional network. Intra-molecular C-H⋯N and C-H⋯Cl hydrogen bonds are also present.

Ha K.,Chonnam National University
Acta Crystallographica Section E: Structure Reports Online | Year: 2011

The Pt II ion in the title complex, [PtBr 2(C 14H 10N 4)], is fourcoordinated in a distorted squareplanar environment by two N atoms of a chelating 2,3-di-2-pyridylpyrazine ligand and two bromide anions. In the crystal, the pyridyl ring coordinated to the Pt atom is inclined slightly to its carrier pyrazine ring [dihedral angle = 14.7 (2)°], whereas the uncoordinated pyridyl ring is inclined considerably to the pyrazine ring [dihedral angle = 51.9 (3)°]. The dihedral angle between the two pyridyl rings is 57.7 (3)°. Two complex molecules are assembled through intermolecular C - H⋯N hydrogen bonds, forming a dimertype species. Intramolecular C - H⋯Br and C - H⋯N hydrogen bonds are also present.