• 한국식품위생안전성학회지
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• 제12권3호
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• pp.217-227
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• 1997

These experiments were performed to investigate the safety of the three medicinal herbs- Curcuma longa Linne, Paeonia japonica Miyabe, Scutellaria baikalensis George-irradiated with gamma rays in respect of genotoxicity. The methanol-soluble and water-soluble fractions of the methanol-water extracts of the 10 kGy gamma-irradiated herbs were examined in two short-term in vitro tests : (1) Salmonella typhimurium reversion assay (Ames test) in strain TA 98, TA 100 and TA 012 (2) Micronucleus test in cultured Chinese hamster ovary (CHO) cells. No mutagenicity was detected in the assays with or without metabolic activation. From these results, the safety of the herbs irradiated with gamma rays at practical doses could be revealed in further tests of genotoxicity in vivo, chronic and reproductive toxiceity.

• Nuclear Engineering and Technology
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• 제6권1호
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• pp.23-26
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• 1974

염화 메탄 슬포닐의 할로겐 교환반응을 무수아세톤, 아세토니트릴, 메타놀 용매중에서 행하여 반응속도상수와 활성화파라메터를 구하였다. 친핵성도는 Cl->Br>I- 순서로 감소하였으며, 용매변화에 따른 염소이온과의 반응 속도는 ($CH_3$)$_2$CO>$CH_3$CN》$CH_3$OH의 순서로 감소하였다. 실험결과를 초기상태 탈용매화의 용이함과 천이상태 용매화의 안정성으로 설명하였다.

• International Journal of Oral Biology
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• 제36권3호
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• pp.149-154
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• 2011

In the present study, total methanol extracts prepared from Alpinia katsumadai showed significant protective effects against the oxidative stress induced by hydrogen peroxide, UV-C or ${\gamma}$-ray irradiation. These protective effects were substantially increased by treatment with 20~100 ${\mu}g$/ml of the extract. The A. katsumadai total methanol preparation was further fractionated into n-hexane, dichloromethane, ethylacetate, n-butanol and water fractions. Among these five fractions, the ethylacetate and butanol fractions of A. katsumadai showed the strongest protective effects against oxidative stress induced by UV-C and ${\gamma}$-ray irradiation. These fractions also showed high DPPH radical scavenging and lipid peroxidation inhibitory activities. In addition, both fractions displayed cell proliferation activation effects, as evidenced by significant increases in colony formation. Our current data thus suggest that the mechanisms underlying the protective effects of A. katsumadai against oxidative damage may include radical scavenging, protection against cell membrane damage and stimulation of cell proliferation.

• Bulletin of the Korean Chemical Society
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• 제8권5호
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• pp.393-398
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• 1987

Solvolyses of 2-phenylethyl benzenesulfonates have been studied in methanol-water mixtures. Cross interaction constants, $\rho_{YZ}$, between substituents Y in the substrate and Z in the leaving group indicated somewhat closer distance between the two substituents than expected for the reaction system, which supported the involvment of phenyl group assisted pathway in the solvolysis. A smaller magnitude of $\rho_{YZ}$for MeOH was interpreted as the enhencement of solvent assisted pathway since MeOH is more nucleophilic than $H_2O$. Other selectivity parameters, Winstein coefficient m, Hammett's $\rho_Y^{+_Y}$ and $\rho_Z$, as well as activation parameters supported the participation of aryl assisted and aryl unassisted pathways in the $S_{N^2}$ process of the solvolysis reaction.

• 대한화학회지
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• 제31권5호
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• pp.413-418
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• 1987

파라니트로 염화벤질(p-NO$_2$), 염화벤질(p-H) 및 파라메틸 염화벤질(p-CH$_3$)과 피리딘 사이의 반응을 메탄올용매내에서 반응시켜 이들의 반응 온도를 40$^{\circ}$C 와 50$^{\circ}$C로 하고, 압력은 1∼2000bar로 변화시켜 전기전도도법으로 측정하여 유사 1차 반응속도 상수와 2차 반응속도 상수를 구하였다. 이때 반응속도 상수는 p-NO$_2$ < p-H < p-CH$_3$의 순으로 증가됨을 알았다. 염화벤질류와 피리딘의 반응속도상수는 온도, 압력이 증가함에 따라 증가하고 피리딘의 농도가 증가할수록 증가하였다. 상기 반응속도 상수로 부터 활성화부피, 활성화 압축율 계수, 활성화엔탈피, 활성화 엔트로피 및 활성화 자유에너지를 구하였다. 활성화 부피와 활성와 압축율 계수는 모두 음의 값이며, 활성화 엔탈피는 양의 값을 활성화 엔트로피는 큰 음의 값을 나타내었다. 이러한 사실로부터 치환체 및 압력에 따른 초기상태와 전이상태를 비교 검토하여 반응메카니즘을 고찰한 결과 전체반응은 S$_N$2반응으로 진행되고 있으나, 압력이 증가함에 따라 S$_N$2반응성이 약화됨을 알았다.

• Journal of Microbiology and Biotechnology
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• 제18권8호
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• pp.1423-1426
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• 2008

Nuruk, which is a natural inoculator and source of amylolytic enzymes, is used in Korean traditional rice wine. A methanol extract of nuruk (NE) attenuated lipopolysaccharide (LPS)-induced nitrite and interleukin (IL)-6 in RAW 264.7 cells. Both the n-hexane and water fractions from NE (MEH and MW, respectively) inhibited the production of nitrite and IL-6 in RAW 264.7 cells. MEH and MW also inhibited the LPS-induced inducible nitric oxide synthase expression. Further, and MEH protected against the LPS-induced activation of p38 mitogen-activated protein kinase. Together, these results indicate that nuruk may contribute to the anti-inflammatory and cancer-preventive effects of Korean traditional rice wine.

• Korean Chemical Engineering Research
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• 제56권3호
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• pp.416-420
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• 2018

A comprehensive kinetic study has been conducted on dimethyl carbonate synthesis by transesterification reaction of ethylene carbonate with methanol. An alkali base metal (KOH) was used as catalyst in the synthesis of DMC, and its catalytic ability was investigated in terms of kinetics. The experiment was performed in a batch reactor at atmospheric pressure. The reaction orders, the activation energy and the rate constants were determined for both forward and backward reactions. The reaction order for forward and backward reactions was 0.87 and 2.15, and the activation energy was 12.73 and 29.28 kJ/mol, respectively. Using the general factor analysis in the design of experiments, we analyzed the main effects and interactions according to the MeOH/EC, reaction temperature and KOH concentration. DMC yield with various reaction conditions was presented for all ranges using surface and contour plot. Furthermore, the optimal conditions for DMC yield were determined using response surface method.

• Bulletin of the Korean Chemical Society
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• 제16권1호
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• pp.53-58
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• 1995

Heats of solution of aniline (AN), benzylamine (BA), ethyl-(EBS) and 2-phenylethyl benzenesulfonates (PEB) are calorimetrically measured in acetonitrile-methanol mixtures at 25.0 $^{\circ}C$. The activation parameters, ${\Delta}H^{\neq}$, ${\Delta}S^{\neq}$ and ${\Delta}G^{\neq}$, are determined for the reactions of EBS and PEB with AN and BA using the kinetic data at three temperatures. Calorimetric transfer enthalpies of initial state, ${\delta}H_t^{0{\rightarrow}x})$(IS), and kinetically derived activation enthalpies, ${\delta}\;{\Delta}H^{\neq}$, in the MeCN-MeOH mixtures are combined to determine the transfer enthalpies of transition state, ${\delta}H_t^{0{\rightarrow}x})$(TS); ${\delta}H_t^{0{\rightarrow}x})$(IS) = ${\delta}{\Delta}H^{\neq}\;+\;{\delta}H_t^{0{\rightarrow}x}$(IS) The preferential solvation of anionic charge in the TS predicts a loose TS with a greater degree of bond cleavage for the reactions of PEB than for EBS, and also for the reactions with BA compared to the reactions with AN.

• 대한화학회지
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• 제63권4호
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• pp.233-236
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• 2019

In this study, the solvolysis of cyclohexanesulfonyl chloride (1) was studied by kinetics in ethanol-water, methanol-water, acetone-water, and 2,2,2-trifluoroethanol (TFE)-water binary solvent systems. The rate constants were applied to the extended Grunwald-Winstein equation, to obtain the values of m = 0.41 and l = 0.81. These values suggested $S_N2$ mechanism in which bond formation is more important than bond breaking in the transition state (TS). Relatively small activation enthalpy values (11.6 to $14.8kcal{\cdot}mol^{-1}$), the large negative activation entropy values (-29.7 to $-38.7cal{\cdot}mol^{-1}{\cdot}K^{-1}$) and the solvent kinetic isotope effects (SKIE, 2.29, 2.30), the solvolyses of the cyclohexanesulfonyl chloride (1) proceeds via the $S_N2$ mechanism.

• 한국어업기술학회:학술대회논문집
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• 한국어업기술학회 2001년도 춘계 수산관련학회 공동학술대회발표요지집
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• pp.201-202
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• 2001

Mass culture of microalgae as feed for mollusc, crustaceans and fish is an important components of the mariculture industry (Metting Jr., 1996) Growth activator for tetraselmis suecica were screened in methanol and water soluble extracts of several seaweed tissues. Also examined in this study were change in growth rate, biochemical composition, and digestion efficiency, of T.suecica cultured with and without the most effective of these extracts, the water soluble component extracted form M. nitidium. (omitted)