Nakhon Ratchasima, Thailand
Nakhon Ratchasima, Thailand

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Plerdsranoy P.,Suranaree University of Technology | Kaewsuwan D.,Synchrotron Light Research Institute | Chanlek N.,Synchrotron Light Research Institute | Utke R.,Suranaree University of Technology
International Journal of Hydrogen Energy | Year: 2017

The effects of specific surface area (SBET) and total pore volume (Vtot) of activated carbon nanofibers (ACNF) on nanoconfinement and dehydrogenation of LiBH4 are investigated. By varying activation time from 15 to 75 min, SBET and Vtot of ACNF are altered in the ranges of 509-2752 m2/g and 0.38-2.17 mL/g, respectively. Melt infiltration of LiBH4 in ACNF is improved with the increment of SBET and Vtot. Due to effective melt infiltration, not only high hydrogen content desorbed (up to 81% of theoretical capacity), but also the release of B2H6 is suppressed. All nanoconfined LiBH4 in ACNF show the main dehydrogenation at comparable temperature of 347-352 °C, implying that kinetic improvement is mainly from catalytic effects of carbon surface. However, effective nanoconfinement yields considerable reduction of onset and main dehydrogenation temperatures to 275 and 305 °C, respectively (δT = 125 and 170 °C, respectively, as compared with bulk LiBH4). Via re-melting the as-prepared sample, further melt infiltration of LiBH4 into voids and/or small pores of ACNF can be obtained. The latter leads to closer contact and more interaction with carbon surface, resulting in the reduction of onset dehydrogenation temperature toward 268 °C and the enhancement of relative content of hydrogen released at low temperature (305 °C). Thus, multiple times or long length of time for melt infiltration can be an interesting choice to increase LiBH4 content up to the maximum loading of ACNF. © 2017 Hydrogen Energy Publications LLC.

Na Phattalung S.,Kasetsart University | Limpijumnong S.,Suranaree University of Technology | Limpijumnong S.,Synchrotron Light Research Institute | Yu J.,Seoul National University
Applied Catalysis B: Environmental | Year: 2017

Aiming for the enhanced photocatalytic activity of titanium dioxide (TiO2), we probe various co-doping pairs of impurity atoms in TiO2 in search of the right co-dopants which can reduce the bandgap without creating recombination centers. To confirm the band edges and the relative positions of impurity levels, we perform first-principles density-functional-theory calculations within the local density approximation as well as the hybrid functional approach. From the analysis of the bandgaps of doped-TiO2 and the defect levels, we propose that the vanadium-nitrogen (V-N) pair is a suitable passivated co-dopant in TiO2. By doping TiO2 with the V-N pair, the bandgap of TiO2 is reduced; enhancing the visible light absorption. The calculated band edges after doping also matches the redox potentials of hydroxyl radical ([Formula presented]) and superoxide anion (O2[Formula presented]−); enhancing the photocatalytic activity for the degradation of organic pollutants and acting as antibacterial agents as well. © 2016 Elsevier B.V.

Juntong N.,Synchrotron Light Research Institute | Pharaphan K.,Synchrotron Light Research Institute
IPAC 2016 - Proceedings of the 7th International Particle Accelerator Conference | Year: 2016

The x-ray target in medical electron linear accelerator is an important part in the production of x-ray photon beam. X-ray dose rate is depended on materials and thickness of the target. For the low cost 6 MeV prototype of medical linac in Thailand, this study gives the optimized x-ray target in which the dose rate can be maximized. MCNP simulations were performed during an optimization for a high x-ray dose rate at 1 meter away from the target. Progression of the project is also presented. Copyright © 2016 CC-BY-3.0 and by the respective authors.

Doydora S.,North Carolina State University | Hesterberg D.,North Carolina State University | Klysubun W.,Synchrotron Light Research Institute
Soil Science Society of America Journal | Year: 2017

Less than 40% of fertilizer phosphate applied to soils is generally taken up by crops because of strong retention of P by soil solids. Our objective was to determine mechanisms by which AVAIL, a maleic-itaconic copolymer used as a fertilizer additive, potentially affects retention of applied phosphate, and consequently plant availability. We measured competitive sorption of AVAIL and orthophosphate in aqueous suspensions of ferrihydrite and poorly crystalline Al hydroxide [pxl-Al(OH)3] at pH 6.2, and characterized phosphate bonding distribution between Fe(III) and Al(III) in 1:1 (w/w) mixtures of these solids using P K-edge X-ray absorption near edge structure (XANES) spectroscopy. With increasing co-Additions of AVAIL and P at the levels evaluated, sorption results showed dissolved P increasing up to 0.45 and 1.25 mM for ferrihydrite and pxl-Al(OH)3, respectively, which represented 18 and 34% of added P. Negative relationships between sorbed P and sorbed AVAIL implied a competitive adsorption mechanism between these two ligands, and solubilization of Fe by AVAIL indicated complexometric dissolution of ferrihydrite. The XANES results showed that 72 to 86% of sorbed P was bonded with Al(III) in the ferrihydrite/pxl-Al(OH)3 mixtures, with only a minor (<15%) effect of AVAIL apparent when P was applied at the two levels tested in this study. Our results suggest that optimized AVAIL application rates for enhancing crop availability of P would depend on soil sorption characteristics and the soil content of residual P relative to its soil sorption capacity. © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA. All Rights reserved.

T-Thienprasert J.,Kasetsart University | Rujirawat S.,Suranaree University of Technology | Klysubun W.,Synchrotron Light Research Institute | Duenow J.N.,National Renewable Energy Laboratory | And 4 more authors.
Physical Review Letters | Year: 2013

The synchrotron x-ray absorption near edge structures (XANES) technique was used in conjunction with first-principles calculations to characterize Al-doped ZnO films. Standard characterizations revealed that the amount of carrier concentration and mobility depend on the growth conditions, i.e. H2 (or O2)/Ar gas ratio and Al concentration. First-principles calculations showed that Al energetically prefers to substitute on the Zn site, forming a donor AlZn, over being an interstitial (Ali). The measured Al K-edge XANES spectra are in good agreement with the simulated spectra of AlZn, indicating that the majority of Al atoms are substituting for Zn. The reduction in carrier concentration or mobility in some samples can be attributed to the AlZn-VZn and 2Al Zn-VZn complex formations that have similar XANES features. In addition, XANES of some samples showed additional features that are the indication of some α-Al2O3 or nAl Zn-Oi formation, explaining their poorer conductivity. © 2013 American Physical Society.

Poo-Arporn Y.,Synchrotron Light Research Institute | Palangsuntikul R.,King Mongkut's University of Technology Thonburi
Journal of Nanoscience and Nanotechnology | Year: 2016

The in situ X-ray absorption near edge structure (XANES) measurement and linear combination fitting were applied to monitor phase transformation of titanium dioxide. In this study, TiO2 (TiSG) was prepared by a sol-gel method using titanium isopropoxide as a precursor. At low preparation temperature, the results revealed the formation of an amorphous structure. To obtain the anatase phase, the calcination at 843 K was necessary. Using phase fraction plot, TiO2 phase-transition can be observed at temperatures between 748 and 778 K and remain unchanged at 873 K. Copyright © 2016 American Scientific Publishers All rights reserved.

Sinyoung S.,King Mongkut's University of Technology Thonburi | Songsiriritthigul P.,Synchrotron Light Research Institute | Songsiriritthigul P.,Suranaree University of Technology | Asavapisit S.,King Mongkut's University of Technology Thonburi | And 2 more authors.
Journal of Hazardous Materials | Year: 2011

The behavior of chromium during the production of cement clinker, during the hydration of cement and during the leaching of cement mortars was investigated. The microstructures of clinker and mortar properties were investigated using free lime, XRD, SEM/EDS, and TG/DTA techniques. Chromium was found to be incorporated in the clinker phase. The formation of new chromium compounds such as Ca6Al4Cr2O15, Ca5Cr3O12, Ca5Cr2SiO12, and CaCr2O7, with chromium oxidation states of +3, +4.6, +5, and +6, respectively, was detected. After the hydration process, additional chromium compounds were identified in the mortar matrix, including Ca5(CrO4)3OH, CaCrO4·2H2O, and Al2(OH)4CrO4, with chromium oxidation states of +4.6, +6, and +6, respectively. Additionally, some species of chromium, such as Cr3+ from Ca6Al4Cr2O15 and Cr6+ from CaCr2O7, CaCrO4·2H2O, and Al2(OH)4CrO4, were leached during leaching tests, whereas other species remained in the mortar. The concentrations of chromium that leached from the mortar following U.S. EPA Method 1311 and EA NEN 7375:2004 leaching tests were higher than limits set by the U.S. EPA and the Environment Agency of England and Wales related to hazardous waste disposal in landfills. Thus, waste containing chromium should not be allowed to mix with raw materials in the cement manufacturing process. © 2011 Elsevier B.V.

Soontaranon S.,Synchrotron Light Research Institute | Rugmai S.,Synchrotron Light Research Institute | Rugmai S.,Suranaree University of Technology
Chinese Journal of Physics | Year: 2012

A Small Angle X-ray Scattering (SAXS) beamline has been constructed at the Siam Photon Laboratory (SPL) of the Synchrotron Light Research Institute (SLRI). The SAXS beamline is dedicated for nano structural characterization of materials. The synchrotron light originated from a bending magnet is monochromatized using a Double Multilayer Monochromater (DMM) to provide x-ray in the energy range of 6-9 keV. A toroidal mirror is used to focus x-ray to the sample position. The experimental station is equipped with a CCD detector, in which the sample-detector distance can be extended to up to 4 m. The beamline has been commissioned and opened for users in March 2011. The commissioning result of the beamline, including SAXS measurement of nano particles, is presented. © 2012 The Physical Society of the Republic of China.

Thungprasert S.,Chiang Mai University | Sarakonsri T.,Chiang Mai University | Klysubun W.,Synchrotron Light Research Institute | Vilaithong T.,Chiang Mai University
Journal of Alloys and Compounds | Year: 2011

In this research, Pt-based ternary catalysts for proton exchange membrane fuel cell (PEMFC) have been successfully prepared by the solution route method. This type of catalyst was claimed to improve the activities of oxygen reduction reaction (ORR). The ternary catalyst was prepared using 10% platinum, 5% cobalt, and 5% chromium by weight support on untreated and treated carbons by reduction with NaBH4 at room temperature. The FTIR spectra showed a new functional group as carboxyl group on treated carbon using H2O 2. The XRD patterns for both carbon samples confirmed platinum and carbon phases in the products. The EDS spectra detected platinum, cobalt, chromium, oxygen and carbon atoms in the prepared catalysts. The XAS patterns revealed that the products were mixed Pt-CoO-Cr2O3 catalysts. The SEM and TEM images showed more dispersion of catalyst on the treated carbon support surface than on the untreated carbon support. Particles size were 3.97 nm for untreated carbon and 1.93 nm for treated carbon. Finally, the electrochemical property was tested by CV technique. It indicated that Pt-CoO-Cr2O3/C catalyst supported on treated carbon exhibited the highest performance among the prepared ternary alloy catalysts. © 2011 Elsevier B.V. All rights reserved.

Patton R.J.,University of Hull | Klinkhieo S.,Synchrotron Light Research Institute
Proceedings of the 2010 American Control Conference, ACC 2010 | Year: 2010

This work is motivated by the challenge to develop an adaptive strategy for systems that are complex, have actuator faults and are difficult to control using linear methods. The novelty lies in combined use of LPV fault estimation and LPV fault compensation to meet active FTC performance requirements. The paper proposes a new design approach for systems which can be characterized via sets of LMIs and can be obtained using efficient interior-point algorithms. A polytopic LPV estimator is synthesized for generating actuator fault estimates used in an FTC scheme to schedule the nominal system state feedback gain, thereby maintaining the system performance over a wide operating range within a proposed polytopic model. The active FTC controller is a function of fault effect factors derived on-line. The effectiveness of the proposed method is demonstrated through a nonlinear two-link manipulator system with torque input faults at each joint. © 2010 AACC.

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