• Bulletin of the Korean Chemical Society
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• 제2권2호
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• pp.71-75
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• 1981

Vacuum ultraviolet photolysis of ethyl bromide was studied at 104.8-106.7 nm (11.4-11.6 eV) in the pressure range of 0.2-18.6 torr at $25^{\circ}$ using an argon resonance lamp with and without additives, i.e., NO and He. Since the ionization potential of $CH_3CH_2Br$ is lower than the photon energy, the competitive processes between the photoionization and the photodecomposition were also investigated. The observations indicated that 50% of absorbed light leads to the former process and the rest to the latter one. In the absence of NO the principal reaction products for the latter process were found to be $CH_4, C_2H_2, C_2H_4, C_2H_6, and C_3H_8$. The product quantum yields of these reaction products showed two strikingly different phenomena with an increase in reactant pressure. The major products, $C_2H_4$ and $C_2H_6$, showed positive effects with pressure whereas the effects on minor products were negative in both cases, i.e., He and reactant pressures. Addition of NO completely suppresses the formation of all products except $C_2H_4$ and reduces the $C_2H_4$ quantum yield. These observations are interpreted in view of existence of two different electronically excited states. The initial formation of short-lived Rydberg transition state undergoes HBr molecular elimination and this state can across over by collisional induction to a second excited state which decomposes exclusively by carbon-bromine bond fission. The estimated lifetime of the initial excited state was ${\sim}4{\times}10^{-10}$ sec. The extinction coefficient for $CH_3CH_2Br$ at 104.8-106.7 nm and $25{\circ}$ was determined to be ${varepsilon} = (1/PL)ln(I_0/I_t) = 2061{\pm}160atm^{-1}cm6{-1}$ with 95% confidence level.

• Composites Research
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• 제21권1호
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• pp.16-21
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• 2008

The cure behavior of epoxy resin with a conventional amide-type hardener(HD) was investigated in the presence of castor oil(CO), cashew nut shell liquid(CNSL) and CNSL-formaldehyde resin(CFR) by using a dynamic differential scanning calorimetry(DSC). The activation energy of curing reaction was also calculated based on the non-isothermal DSC thermograms at various heating rates. An one-stage curing was noted in the case of epoxy resin filled with CO, while the epoxy resin with CNSL and CFR showed a two-stage curing process. A competitive cure reaction was noted for the epoxy resin/CNSL(or CFR)/HD blends. In the absence of HD, the CFR showed lower values of curing enthalpy than that of CNSL. The activation energy of epoxy resin curing increased with increasing the CNSL and CFR loading.

• Journal of the Korean Chemical Society
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• 제40권6호
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• pp.445-452
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• 1996

Catalytic hydrogenation of ketones and aldehydes by RuH(NO)$L_3$ ($L_3$: $PPh_3$, PhP($CH_2CH_2PPh_2$)$_2$(etp)) was investigated to examine the reaction mechanism and the competence of hydridonitrosyl complexes as catalysts for organic synthesis. RuH(NO)$L_3$ showed catalytic activity for the hydrogenation and the activities of catalysts were dependent on the steric and electronic factors. The less the steric demands of the substrates become, the more activity the catalysts show. For the electronic effect, the more the partial positive charge on the carbonyl carbon atom in ketones becomes and the more the double bond character of carbonyl group in aldehydes becomes, the more active the catalysts are. These results reflect the difference of reaction mechanisms of two substrates, ketones and aldehydes. Catalytic activities of RuH(NO)(etp) and RuH(NO)($PPh_3$)$_3$ in the presence of extra $PPh_3$ toward hydrogenation showed the existence of a reaction pathway accompanied with the change of the bonding modes of NO ligand. The roles of excess $PPh_3$ change with increase of the mole ratio of $PPh_3$ to catalysts; prevention of ligand dissociation from comlexes → bases → ligands. The activity of RuH(NO)(etp) was lower than that of RuH(NO)($PPh_3$)$_3$ toward the hydrogenation of the same substrates mainly due to the structural difference. These catalysts showed the selectivity toward olefin hydrogenation over carbonyl groups in the competitive reaction.

• Korean Journal of Clinical Laboratory Science
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• 제49권3호
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• pp.220-226
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• 2017

Dopamine (DA) and serotonin (5-Hydroxytryptamine, 5-HT) are neurotransmitters and hormones that exist in small amounts but have important role in the body. Serum and 24-hour urine are used as specimens, and are usually examined by HPLC-MS. In this study, we tried to detect DA and 5-HT by competitive ELISA using antigen-antibody (Ab) reaction. After immobilizing $5{\mu}g/mL$ BSA conjugate on a 96-well surface, hormone and primary Ab, which are respectively diluted to different concentrations, were treated. Then, HRP-conjugated secondary Ab and TMB were added to measure absorbance. The regression equation and $R^2$ value were calculated based on absorbance, and sensitivity of Ab to hormone as well as the correlation between hormone concentration and absorbance were determined. In DA ELISA, $R^2$, the correlation between the concentration of hormone and absorbance, was the highest by 0.91 when anti-dopamine Ab was diluted 6,000 times and 7,000 times. In 5-HT ELISA, $R^2$ was bigger than 0.90 in every concentration except 3,000 times and 6,000 times. Both DA and 5-HT were not effectively detected at low concentrations (less than $1.0{\times}10^{-7}M$); and because reference value of serum DA is lower than this, HPLC-MS was required to detect serum DA. However, competitive ELISA may be effective in detecting 24-hour urine DA, serum, and 24-hour 5-HT. Further studies are needed to detect hormones more accurately at lower concentrations.

• Proceedings of the Korean Vacuum Society Conference
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.212-212
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• 2012

The Coverage dependent attachment of multifunctional groups included in threonine molecules adsorbed to Ge (100)$-2{\times}1$ surface was investigated using core-level photoemission spectroscopy (CLPES) and density functional theory (DFT) calculations. The core-level spectra at a low coverage indicated that the both carboxyl and amine groups participated in the bonding with the Ge (100) surface by "O-H dissociated and N-dative bonded structure". However, at high coverage level, additional adsorption geometry of "O-H dissociation bonded structure" appeared possibly to minimize the steric hindrance between adsorbed molecules. Moreover, the C 1s, N 1s, and O 1s core level spectra confirmed that the carboxyl oxygen is more competitive against the hydroxymethyl oxygen in the adsorption reaction. The adsorption energies calculated using DFT methods suggested that four of six adsorption structures were plausible. These structures were the "O-H dissociated-N dative bonded structure", the "O-H dissociation bonded structure", the "Om-H dissociated-N dative bonded structure", and the "Om-H dissociation bonded structure" (where Om indicates the hydroxymethyl oxygen). These structures are equally likely, according to the adsorption energies alone. Conclusively, we investigate in threonine on Ge (100) surface system that the "O-H dissociated-N dative bonded structure" and the "O-H dissociation bonded structure" are preferred at low coverage and high coverage.

• The Journal of Asian Finance, Economics and Business
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• 제7권6호
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• pp.495-508
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• 2020

Economic integration is an indispensable trend in all countries. However, besides the advantages that economic integration brings, there are also disadvantages, such as competition between businesses among states in export activities. Vietnam is a developing country with many advantages, especially, the seafood exporting industry. However, with competitive pressure as well as strategic constraints, Vietnamese seafood exporters still face many difficulties. Therefore, the case study of the Kien Giang province of Vietnam is used to analyze the factors affecting the competitiveness of seafood exporting enterprises. The study applied quantitative research methods with a survey of 350 seafood exporting enterprises in Kien Giang province to achieve the research objectives. The research results identified eleven key factors affecting the competitiveness of seafood exporting enterprises, including (1) vision and strategy of leader; (2) human resources management capability; (3) organization capability; (4) customer-responsive marketing capability; (5) relationship management capability; (6) technical capability; (7) competitors reaction capability; (8) business environment adoption capability; (9) financial capability; (10) products and services innovation capability; and (11) branding management. The research results provided the basis to propose some managerial implications to improve the competitiveness of exporting enterprises in the context of the global economic integration.

• The Plant Pathology Journal
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• 제17권5호
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• pp.295-299
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• 2001

The relative density of phytoplasmas in witches'broom (WB)-infected jujube trees was investigated using compatitive polymerase chain reaction (PCR). During dormant and defoliating seasons, the densities of phytoplasmas were about the same in roots and twigs. In early growing season, the density showed the highest rates in roots, then in twigs and in petioles. however, the density was highest in petioles and the lowest in roots during actively growing season. Throughout the year, root samples did not show any serious fluctuation compared with that of t2wigs and petioles. Density was lowest during actively growing season in root samples. In contrast, petiole sample densities varied to a great extent depending on the season, very high during actively growing season, but very low during the early growing season, In twig samples, the densities were very high and almost the same in both defoliating and dormant seasons. Among the parts of the trees, phytoplsma density was the most stable in root samples throughout the year. The highest densities of phytoplasmas were about the same in all tree parts. These results suggest that the phytoplasmas may overwinter not only in roots but also in twigs, and that multiplication rate of phytoplsma becomes very high right after the early growing season.

• Parasites, Hosts and Diseases
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• 제38권2호
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• pp.107-110
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• 2000

We investigated the role of recombinant Toxoplasma gondii heat shock protein (rT.g.HSP) 70-full length, rT.g. HSP70-NH2-terminal region, or rT.g. HSP70-carboxy-terminal region in prophylactic immunity in C57BL/6 mice perorally infected with Fukaya cysts of T. gondii. At 3, 4, 5, and 6 weeks after infection, the number of T gondii in the brain tissue of each mouse was measured by quantitative competitive-polymerase chain reaction (QC-PCR) targeting the surface antigen (SAG) 1 gene. Immunization with rT.g.HSP70-full length or rT.g.HSP70-carboxy-terminal region increased the number of T. gondii in the brain tissue after T. gondii infection, whereas immunization with rT.g.HSP70-NHa-terminal region did not. These results suggest that T.g. HSP70-carboxy-terminal region as well as T.g.HSP70-full length may induce deleterious effects on the protective immunity of mice infected with a cyst-forming T. gondii strain, Fukaya.

• BMB Reports
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• 제28권2호
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• pp.149-154
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• 1995

Protein methylase II (S-adenosyl-L-methionine : protein O-methyl-transferase, EC 2.1.1.24; PM II) was purified approximately 1250-fold from porcine testis by fractional precipitation and DEAE-cellulose chromatography, followed by gel filtration on a Sephadex G-75 column and HPLC on a Protein Pak 125 column. The molecular weight of the enzyme was estimated to be 33,000 daltons by SDS-PAGE, which agreed with the value determined by gel filtration. Isoelectric focusing of purified PM II showed a single protein species with an isoelectric point of 6.2. The optimum pH for the reaction was 6.0. The $K_m$ value of the enzyme was $1{\times}10^{-5}M$ with a $V_{max}$ value of 769 pmol/min/mg of enzyme. S-adenosyl-L-homocysteine is a competitive inhibitor of PM II with a $K_i$ value of $1.38{\times}10^{-6}M$.

• Korean Journal of Environmental Agriculture
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• 제13권2호
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• pp.191-198
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• 1994

2-Thiophenyltriisopropoxytitanium was prepared in situ by trans-metallization of 2-thiophenyllithium and chlorotitaniumtriisopropoxide. It could be isolated at room temperature and preserved at $-10{\circ}C$ for weeks. The reactivity of 2-thiophenyltriisopropoxytitanium to carbonyl compounds proved to be high. Complete aldehyde-selectivity was observed in competition reactions of 2-thiophenyl-triiso-propoxytitanium with a 1 : 1 mixture of aldehyde and ketone. In the competitive reaction of 2-thiophenyl-triisopropoxytitanium to ketone-ester function, ketone adduct was perfectly obtained.