Jeonju National University of Education

www.jnue.ac.kr/eng/
Jeonju, South Korea

Jeonju National University of Education is a national university located in Jeonju, South Korea. Wikipedia.

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Kang S.J.,Jeonju National University of Education | Koh H.J.,Jeonju National University of Education
Journal of the Korean Chemical Society | Year: 2017

Solvolyses with the reaction center being the sulfur of 4-(chlorosulfonyl)biphenyl (C6H5C6H4SO2Cl, 1) was studied under solvolytic conditions and the extended Grunwald-Winstein equation was applied. The thirty five kinds of solvents gave a reasonable extended Grunwald-Winstein plot with a correlation coefficient (R) of 0.940. The sensitivity values (l = 0.60 and m = 0.47) of 1 were smaller than those obtained for benzenesulfonyl chloride (C6H5SO2Cl, 2; l = 1.10 and m = 0.61) proposed to undergo dissociative SN2 mechanism. These l and m values for the solvolyses of 1 can be considered to support a SN2 pathway with some ionization reaction. The activation parameters, ΔH≠ and ΔS≠, were determined and they are also in line with values expected for a bimolecular reaction. The kinetic solvent isotope effect (KSIE) of 1.26 is also in accord with a bimolecular mechanism, probably assisted by general-base catalysis. © 2017, Korean Chemical Society. All rights reserved.


Koh H.J.,Jeonju National University of Education | Kang S.J.,Jeonju National University of Education | Kevill D.N.,Northern Illinois University
Bulletin of the Korean Chemical Society | Year: 2010

The rate constants of solvolyses of 2,2,2-trichloro-1,1-dimethylethyl chloroformate (I) in 33 solvents can be well correlated using the extended Grunwald-Winstein equation, with incorporation of the NT solvent nucleophilicity scale and the YCl solvent ionizing scale, with sensitivities towards changes in the scale having values of 1.42 ± 0.09 for l and 0.39 ± 0.05 for m, respectively. The activation enthalpies are ΔH≠ = 12.3 to 14.5 kcal·mol-1 and the activation entropies are -28.2 to -35.5 cal·mol -1·K-1, consistent with the proposed bimolecular reaction mechanism. The kinetic solvent isotope effect of 2.14 in MeOH/MeOD is in accord with a bimolecular mechanism, probably assisted by general-base catalysis.


Shamshi Hassan M.,Chonbuk National University | Amna T.,Chonbuk National University | Sheikh F.A.,University of Texas–Pan American | Al-Deyab S.S.,King Saud University | And 3 more authors.
Ceramics International | Year: 2013

The objective of this study was to develop a new class of bimetallic ZnO/Ag embedded polyurethane multi-functional nanocomposite by a straightforward approach. Bimetallic nanomaterials, composed of two unlike metal elements, are of greater interest than the monometallic materials because of their improved characteristics. In the present study the bimetallic composite was prepared using sol-gel via the facile electrospinning technique. The utilized sol-gel was composed of zinc oxide, silver and poly(urethane). The physicochemical properties of as-spun composite mats were determined by X-ray diffraction pattern, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. The antibacterial activity was tested using Escherichia coli as model organism. The antibacterial test showed that ZnO:Ag/polyurethane composite possesses superior antimicrobial activity than pristine PU and ZnO/PU hybrids. Furthermore, our results illustrate that the synergistic effect of ZnO and Ag resulted in the advanced antimicrobial action of bimetallic ZnO/Ag composite mat. The viability and proliferation properties of NIH 3T3 mouse fibroblast cells on the ZnO:Ag/polyurethane composite nanofibers were analyzed by in vitro cell compatibility test. Our results indicated the non-cytotoxic behavior of bimetallic ZnO:Ag/polyurethane nanofibers towards the fibroblast cell culture. In summary, novel ZnO:Ag/polyurethane composite nanofibers which possess large surface to volume ratio with excellent antimicrobial activity were fabricated. The unique combination of ZnO and Ag nanoparticles displayed potent bactericidal effect due to a synergism. Hence the electrospun bimetallic composite indicates the huge potential in water filtration, clinical and biomedical applications. © 2012 Elsevier Ltd and Techna Group S.r.l.


Yao W.,Hebei University of Science and Technology | Han S.-E.,Jeonju National University of Education
Fuzzy Sets and Systems | Year: 2015

We show that for every complete lattice A, both the set of completely prime elements and the set of completely coprime elements are one-to-one corresponding to CH(A), the set of complete lattice homomorphisms from A to the two-element lattice 2. A complete lattice is called completely generated, a cg-lattice for short, if it is generated by the set of completely prime elements, or equivalently, by the set of completely coprime elements. Then we restudy the duality between the category of T0 Alexandrov topological spaces and the category of cg-lattices by means of CH(A). With these preparations, for a frame L as the truth value table, we introduce sT0 separation axiom for stratified Alexandrov L-topological spaces, and finally establish a duality between the category of sT0 stratified Alexandrov L-topological spaces and the category of completely generated complete L-ordered sets. We also investigate some properties of the sT0 axiom, for example, it is hereditary by closed subspaces and productive. © 2014 Elsevier B.V.


Koh H.J.,Jeonju National University of Education | Kang S.J.,Jeonju National University of Education
Bulletin of the Korean Chemical Society | Year: 2011

This report shows the rates of solvolyses for phenyl methanesulfonyl chloride (C6H5CH2SO2Cl, I) in ethanol, methanol, and aqueous binary mixtures incorporating ethanol, methanol, acetone, 2,2,2-trifluroethanol (TFE) and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) are reported. Three representative solvents, studies were made at several temperatures and activation parameters were determined. The thirty kinds of solvents gave a reasonably precise extended Grunwald-Winstein plot, coefficient (R) of 0.954. The sensitivity values (l = 0.61 and m = 0.34, l/m = 1.8) of phenyl methanesulfonyl chloride (I) were smaller than those obtained for benzenesulfonyl chloride (C6H5SO2Cl, II; l = 1.01 and m = 0.61) and 2-propanesulfonyl chloride ((CH3) 2CHSO2Cl, III; l = 1.28 and m = 0.64). As with the two previously studied solvolyses, an SN2 pathway with somewhat ionization reaction is proposed for the solvolyses of I. The activation parameters, ΔH≠ and ΔS≠, were determined and they are also in line with values expected for a bimolecular reaction mechanism. The kinetic solvent isotope effect of 2.34 in CH3OH/ CH3OD is in accord with a bimolecular mechanism, probably assisted by general-base catalysis.


Koh H.J.,Jeonju National University of Education | Kang S.J.,Jeonju National University of Education
Bulletin of the Korean Chemical Society | Year: 2014

The solvolysis rate constants of 5-dimethylamino-naphthalene-1-sulfonyl chloride ((CH3)2NC10H6SO 2Cl, 1) in 31 different solvents are well correlated with the extended Grunwald-Winstein equation, using the NT solvent nucleophilicity scale and YCl solvent ionizing scale with sensitivity values of 0.96 ± 0.09 and 0.53 ± 0.03 for l and m, respectively; the correlation coefficient value was 0.955. These l and m values can be considered to support an SN2 reaction pathway having a transition state (TS) structure similar to that of the benzenesulfonyl chloride reaction. This interpretation is further supported by the activation parameters, i.e., relatively small positive δH≠ (12.0 to 15.9 kcal·mol-1) and large negative δS≠ (-23.1 to -36.3 cal·mol-1·K-1) values, and the solvent kinetic isotope effects (SKIEs, 1.34 to 1.88). Also, the selectivity values (S = 1.2 to 2.9) obtained in binary solvents are consistent with the proposed mechanism.


Kang S.,Jeonju National University of Education
Journal of the Korean Chemical Society | Year: 2012

In this study, the relationship between students' out-of-school science experience and their view on the nature of science was investigated. The participants were 267 sixth graders, 281 eighth graders, and 307 tenth graders from schools in Seoul. A test of views on the nature of science which consists of five items concerning the purpose of science, the definition of scientific theory, the nature of scientific model, the tentativeness of scientific theory, and the origin of scientific theory was administered. Students' out-of-school science experiences were measured with a subscale of the modified Science Experience Survey consisting of seven items. The results indicated that no statistically significant relationship was found between students' out-of-school science experience and their view on the nature of science in sixth graders. In eighth graders, high level students in terms of out-of-school science experiences were found to possess more contemporarily epistemological view in the item concerning the nature of scientific model but more falsificationist view in the item concerning the tentativeness of scientific theory. High level tenth graders in terms of out-of-school science experiences exhibited more epistemologically sophisticated understandings of the nature of science than their counterparts in the items concerning the purpose of science, the definition of scientific theory, and the nature of scientific model.


Kim T.,Jeonju National University of Education
New Physics: Sae Mulli | Year: 2016

Generalized equations which depend on the physical characteristics of the lever and how it is applied are used to calculate the output force on a mass corresponding to an input force. The influence of the lever's physical characteristics and how it is used on the experimental results decreased with increasing lever length; locations of the lever's center of mass, the input force, and the output force; and the weight's mass. However the influence increased with increasing lever thickness, lever mass, position of the fulcrum, difference between the arm lengths for the input and the output force, and the angle of tilt. With increasing ratio of the lever's length to its thickness and the weight's mass to the lever's mass, and with decreasing distance between input force and the fulcrum and distance between the output force and the fulcrum, the dependences of the experimental results on these characteristics and variables abruptly decrease.


Koh H.J.,Jeonju National University of Education | Kang S.J.,Jeonju National University of Education
Bulletin of the Korean Chemical Society | Year: 2012

The solvolysis rate constants of 2,2,2-trichloroethyl chloroformate (Cl3CCH2OCOCl, 3) in 30 different solvents are well correlated with the extended Grunwald-Winstein equation, using the NT solvent nucleophilicity scale and the YCl solvent ionizing scale, with sensitivity values of 1.28 ± 0.06 and 0.46 ± 0.03 for l and m, respectively. The activation enthalpies (ΔH) are 10.1 to 12.8 kcal·mol -1 and the activation entropies (S) are -27.8 to -36.8 cal·mol -1·K -1, which is consistent with the proposed bimolecular reaction mechanism. The kinetic solvent isotope effect (k MeOH/k MeOD) of 2.39 is also in accord with SN2 mechanism probably assisted by general-base catalysis. Copyright © 2005 KCSNET.


Koh H.J.,Jeonju National University of Education | Kang S.J.,Jeonju National University of Education
Bulletin of the Korean Chemical Society | Year: 2012

The solvolysis rate constants of allyl chloroformate (CH 2=CHCH2OCOCl, 3) in 30 different solvents are well correlated with the extended Grunwald-Winstein equation, using the NT solvent nucleophilicity scale and YCl solvent ionizing scale, with the sensitivity values of 0.93 ± 0.05 and 0.41 ± 0.02 for l and m, respectively. These l and m values can be considered to support a S N2 reaction pathway. The activation enthalpies (ΔH≠) were 12.5 to 13.4 kcal·mol-1 and the activation entropies (ΔS≠) were -34.4 to -37.3 cal·mol-1·K -1, which is also consistent with the proposed bimolecular reaction mechanism. The solvent kinetic isotope effect (SKIE, kMeOH/k MeOD) of 2.16 was also in accord with the SN2 mechanism. The values of product selectivity (S) for the solvolyses of 3 in alcohol/water mixtures was 1.3 to 3.9, which is also consistent with the proposed bimolecular reaction mechanism.

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