• The Plant Pathology Journal
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• v.39 no.2
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• pp.181-190
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• 2023

The fungal pathogen Pseudocercospora fuligena, known to affect tomatoes in the tropics and subtropics, has been reported from temperate climates including the United States and Turkey in recent years. In this study, an isolate from fresh tomatoes and the disease it causes were characterized and infection mechanisms investigated. Macroscopically, both sides of tomato leaves show indistinct effuse patches but prolific production of fuliginous lesions is conspicuous on the abaxial side first but also on the adaxial side later on as infection progressed. Microscopically, fascicles of conidiophores (11-128 ㎛ × 3.5-9 ㎛) arising from stromata and conidia with up to 12 septations were observed. Molecular characterization of the isolate revealed high homology (99.8%) to other P. fuligena isolated from tomatoes in Turkey. Out of the 10 media tested, P. fuligena grew significantly well and sporulated better on unsealed tomato oatmeal agar and carrot leaf decoction agar, both supplemented with CaCO₃. Direct transfer of conidia from profusely sporulating lesions was the easiest and quickest method of isolation for in-vitro studies. Light and scanning electron microscopy on cleared and intact tomato leaves further confirmed stomatal penetration and egress as well as prevalence of primary and secondary infection hyphae. In situ, blocked stomatal aperture areas of 154, 401, and 2,043 ㎛² were recorded at 7, 12, and 17 days after inoculation, respectively. With the recent expanded horizon of the pathosystem and its consequential impact, such studies will be useful for a proper diagnosis, identification and management of the disease on tomato worldwide.

• Nuclear Engineering and Technology
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• v.55 no.8
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• pp.2742-2746
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• 2023

The corrosion behavior of copper immersed in dilute oxychloride solution (100 mM) was studied through surface investigation and in-situ monitoring of open-circuit potential. The copper corrosion was initiated with copper dissolution into a form of CuCl^-₂, resulting in mass decrease within the first 40 h of immersion. This was followed by a hydrolysis reaction initiated by the CuCl^-₂ at the copper surface, after which oxide products were formed and deposited on the surface, resulting in a mass increase. The formation of nucleation sites for copper oxide and its lateral extension during the corrosion process were examined using focused ion beam (FIB)-scanning electron microscopy (SEM). The presence of metastable compounds such as atacamite (CuCl₂·3Cu(OH)₂) on the corroded copper surface was revealed by X-ray photoelectron spectra (XPS) and transmission electron microscopy (TEM)-energy dispersive spectrometry (EDS) analysis.

• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3218-3224
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• 2012

Uniform and well dispersed metal sulfide semiconductor nanoparticles incorporated into matrices of alginate biopolymer are prepared by using a facile in situ method. The reaction was accomplished by impregnation of alginate with divalent metal ions followed by reaction with thioacetamide. XRD analysis showed that the nanoparticles incorporated in the polymer matrix were of cubic structure with the average particle diameter of 1.8 to 4.8 nm. Field emission scanning electron microscopy and high resolution transmission electron microscopy images indicated that the particles were well dispersed and distributed uniformly in the matrices of alginate polymer. FT-IR spectra confirmed the presence of alginate in the nanocomposite. The crystalline nature and thermal stability of the alginate polymer was found to be influenced by the nature of the divalent metal ions used for the synthesis. The proposed method is considered to be a simple and greener approach for large scale synthesis of uniform sized nanoparticles.

• Nuclear Engineering and Technology
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• v.52 no.9
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• pp.2054-2063
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• 2020

The high-temperature oxidation behavior of ZrSi₂ used as a coating material for nuclear fuel cladding was investigated for developing accident-tolerant fuel cladding of light water reactors. Bulk ZrSi₂ samples were prepared by spark plasma sintering. In situ X-ray diffraction was conducted in air at 900, 1000, and 1100 ℃ for 20 h. The microstructures of the samples before and after oxidation were examined by scanning electron microscopy and transmission electron microscopy. The results showed that the oxide layer of zirconium silicide exhibited a layer-by-layer structure of crystalline ZrO₂ and amorphous SiO₂, and the high-temperature oxidation resistance was superior to that of Zircaloy-4 owing to the SiO₂ layer formed. ZrSi₂ was coated on the Zircaloy-4 tube surface using laser 3D printing, and the coated tube was oxidized for 2000 s at 1200 ℃ under a vapor/argon mixture atmosphere. The outer surface of the coated tube was hardly oxidized (10-30 ㎛), while the inner surface of the uncoated tube was significantly oxidized to approximately 300 ㎛.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.37.2-37.2
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• 2011

The growth of three-dimensional ZnO hybrid structures by metal-organic chemical vapor deposition was controlled through their growth pressure. Vertically aligned ZnO nanorods were grown on c-plane sapphire substrate at $600^{\circ}C$ and 400 Torr. ZnO film was then formed in-situ on the ZnO nanorods at $600^{\circ}C$ and 10 Torr. High-resolution X-ray diffraction and transmission electron microscopy measurements showed that the ZnO film on the nanorods/sapphire grew epitaxially, and that the ZnO film/nanorods hybrid structures had well-ordered wurtzite structures. The hybrid ZnO structure was shown to be about 5 ${\mu}m$ by field-emission scanning electron microscopy. The hybrid structure showed better crystalline quality than mono-layer film on sapphire substrate. Consequently, purpose of this work is developing high quality hybrid epi-growth technology using nano structure. These structures have potential applicability as nanobuilding blocks in nanodevices.

• Macromolecular Research
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• v.17 no.5
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• pp.301-306
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• 2009

This work has demonstrated that a novel amphiphilic poly(epichlorohydrine)-graft-polystyrene (PECH-g-PS) copolymer at 34:66 wt% was synthesized via atom transfer radical polymerization (ATRP) of styrene using PECH as a macroinitiator. The structure of the graft copolymer was characterized by nuclear magnetic resonance ($^1H$ NMR) and FTIR spectroscopy, demonstrating that the "grafting from" method using ATRP was successful. The self-assembled graft copolymer was used as a template film for the in-situ growth of silver nanoparticles from $AgCF_3SO_3$ precursor under UV irradiation. The in situ formation of silver nanoparticles with 6-8 nm in average size in the solid state template film was confirmed by transmission electron microscopy (TEM), UV-visible spectroscopy and wide angle X-ray scattering (WAXS). Differential scanning calorimetry (DSC) also displayed the selective incorporation and the in situ formation of silver nanoparticles within the hydrophilic PECH domains, probably due to stronger interaction of the silvers with the ether oxygens of PECH backbone than that with hydrophobic PS side chains.

• Journal of Electrochemical Science and Technology
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• v.7 no.4
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• pp.277-285
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• 2016

There is a growing demand for simple, cost-effective, and accurate analytical tools to determine the concentrations of biological and environmental compounds. In this study, a stable electroactive thin film of cobalt hexacyanoferrate (Cohcf) was prepared as an in situ chemical precipitant using electrostatic adsorption of $Co^{2+}$ on a silicate sol-gel matrix (SSG)-modified indium tin oxide electrode pre-adsorbed with $[Fe(CN)_6]^{3-}$ ions. The modified electrode was characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and electrochemical techniques. Electrocatalytic oxidation of hydrazine on the modified electrode was studied. An electrochemical sensor for hydrazine was constructed on the SSG-Cohcf-modified electrode. The oxidation peak currents showed a linear relationship with the hydrazine concentration. This study provides insight into the in situ growth and stability behavior of Cohcf nanostructures and has implications for the design and development of advanced electrode materials for fuel cells and sensor applications.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.20 no.2
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• pp.161-170
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• 2022

The effect of oxidation time on the characteristics and mechanical properties of spent nuclear fuel cladding was investigated using Raman spectroscopy, tube rupture test, and tensile test. As oxidation time increased, the Raman peak associated with the tetragonal zirconium oxide phase diminished and merged with the Raman peak associated with the monoclinic zirconium oxide phase near 333 cm^-1. Additionally, the other tetragonal zirconium oxide phase peak at 380 cm^-1 decreased after 100 d of oxidation, whereas the zirconium monoclinic oxide peak became the dominant peak. The oxidation time had no effect on the tube rupture pressure of the oxidized zirconium alloy tube. However, the yield and tensile stresses of the oxidized nuclear fuel cladding tube decreased after 100 d of oxidation. The results of the scanning electron microscopy and transmission electron microscopy were represented with the in-situ Raman analysis result for the oxide characteristics generated on the cladding of spent nuclear fuel.

• Applied Chemistry for Engineering
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• v.3 no.3
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• pp.499-506
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• 1992

Copolymer of Styrene and GMA(glycidyl methachylate), having reactive ratios of $r_1=0.53$, $r_2=0.44$, was synthesized in dioxane using AIBN as free radical initiator. Followed by the reaction of ethylene diamine with copolymer PGS, amine groups were introduced to the PGS(NPGS). The composition of copolymer was determined by elemental analyzer. Poly(glycidyl methacrylate) (PGMA) was obtained in benzene using AIBN as free radical initiator. The NPGS-PGMA blend of 50/50 composition was prepared by mixing these polymers in THF at $65^{\circ}C$. Glass transition temperature (Tg) of NPGS-PGMA blend was measured by DSC. The blend showed a single Tg. Accordingly, it was clear that the NPGS was compatible with PGMA. An intermolecular reaction between amine groups of NPGS and epoxy groups of PGMA imparts compatibility in the NPGS-PGMA blend. When the NPGS-PGMA blend was added to the incompatible PS-PGMA blend, PS-PGMA blend showed Tg change. Scanning Electron Micrograph(SEM) showed a fine morphology in this blend. Consequently, it was apparent that the NPGS-PGMA blend acted as a compatibilizer for the PS-PGMA blend.

• Polymer(Korea)
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• v.37 no.4
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• pp.507-512
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• 2013

A graphene/waterborne polyurethane (WPU) nano composite was prepared by in-situ polymerization of PU and graphene having isocyanate (iGO) group in order to improve physicochemical/electrical characteristics. The properties of the graphene/WPU nanocomposite can effectively be enhanced as compared pristine WPU; up to 57% of tensile strength and $10^2$ fold of electrical conductivity with introduction of 2 wt% graphene. In addition, mechanical/electrical properties of the graphene/WPU nanocompsite were higher than those of graphene/WPU composite prepared by a simple physical blend method. It might attribute to homogeneous dispersion of iGO in the WPU matrix via covalent bonds and hydrogen bonds between WPU and iGO from the results of morphological analysis by scanning electron microscopy (SEM).