• 대한화학회지
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• 제10권1호
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• pp.18-24
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• 1966

액체 내에는 분자들 주위에 분자크기의 빈자리가 들어 있게 되어 빈자리로 뛰어들면서 기체와 같은 자유도를 갖는 분자와, 빈자리에서 좀 떨어져서 고체와 같은 자유도를 갖는 분자와, 빈자리 때문에 변형에너지를 받고서 천이상태에 있는 분자들이 있다고 가정하여 액체에 대한 상태함을 유도하여 알곤, 질소, 벤젠, 클로로포름 및 이황화탄소의 액체상태에서의 열역학적 성질들을 계산한 결과 실측치와의 좋은 일치를 얻었다.

• Bulletin of the Korean Chemical Society
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• 제27권11호
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• pp.1752-1756
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• 2006

This study explores and interprets in a new way the complex solvent and the temperature dependence of the NMR shifts for the N-$CH_2$ protons in tris(N,N-diethyldithiocarbamato) iron(III) in acetone, benzene, carbon disulfide, chloroform, dimethylformamide and pyridine. The NMR shifts are interpreted in terms of the Fermi contact interaction and the dipolar term from the multipole expansion of the interaction of the electron orbital angular momentum and the electron spin dipolar-nuclear spin angular momentum. This analysis yields a direct measure of the effect of the solvent system on the environment of the transition metal ion. The results are analysed in terms of the crystal field environment of the transition metal ion with contributions from (a) the dithiocarbamate ligand (b) the solvent molecules and (c) the interaction of the effective dipole moment of the polar solvent molecule with the transition metal ion complex.

• 한국식품과학회지
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• 제28권1호
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• pp.15-18
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• 1996

국내외 시판되고 있는 roasted and ground 커피 20종에 대해서 맛에 영향을 미칠 수 있는 이화학적 성분을 분석하였다. 신맛이 강한 R & G 커피의 평균 pH는 5.02, TA는 3.98, 배전색도는 54.7이었으며, 신맛이 약한 R & G 커피의 평균 pH는 5.40, TA는 2.27, 배전색도는 34.6으로 향기성분중 2-methylfuran은 커피의 거친맛(harshness)과 관계하며 배전정도가 강할수록 눈에 띄게 증가하였으므로 이들 관계는 측정치에서 산출된 회귀식 Y=4.45-0.06 X에 의해서 이 관계를 71.2%정도 설명할 수 있다.

• Archives of Pharmacal Research
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• 제20권6호
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• pp.620-628
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• 1997

6-Aryl-5-cyano-4-pyrimidinon-2-thione derivatives 1a-c reacted with ethyl iodide to give the corresponded 2-S-ethylpyrimidin-4-one-derivatives 2a-c. Compounds 2a-c was, in turn, reacted with hydrazine hydrate to give the sulfur free reaction products, 3a-c. These reaction products were taken as the starting materials for the synthesis of several newly synthesized heterocyclic derivatives. Reactions with several halogenated ketones, esters, chloroacetic acid and chloroacetamide give pyrimidotriazines 8,12 and 15 while their reactions with formic acid, acetic acid and carbon disulfide gave the corresponded triazolopyrimidines 17 and 21. The reaction with both acetyl acetone and ethylacetoacetate gave the corresponded 2-$(3^{I},5^{I}-dimethyl-1^{I}-pyrazoly$pyrimidine derivatives 20a-c and 24a-c respectively while the reaction with cinnamonitriles 25a-h afforded the corresponded aryl hydrazopyrimidines 27a-f. The structure of these reaction products were eatablished based on both elemental anlayses and spectral data studies.

• 공업화학
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• 제22권2호
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• pp.144-148
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• 2011

본 연구에서는 화학적 구조가 다른 thiuram 계 촉진제인 TMTD (tetramethyl thiuram disulfide), thiazole 계 촉진제인 MBTS (2,2-dithiobis(benzothiazole)), sulfenamide 계 촉진제인 CBS (n-cyclohexyl benzothiazyl-2-sulfenamide)를 사용하여 각각의 촉진제가 실리카가 충전된 천연고무의 가황 특성에 미치는 영향을 비교 평가하였다. TMTD는 상대적으로 빠른 가류 속도와 높은 최대 토크값($T_{max}$), 우수한 기계적 물성을 보였고 MBTS는 상대적으로 중간 정도의 가황 시간과 낮은 $T_{max}$, 기계적 물성을 보였다. 마지막으로 CBS는 느린 가황 시간을 나타낸 반면 상대적으로 우수한 $T_{max}$와 기계적 물성을 나타냈다. 유사한 가황 특성 경향은 카본블랙이 충전된 천연고무 컴파운드에서도 찾아볼 수 있었다.

• Corrosion Science and Technology
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• 제21권4호
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• pp.250-257
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• 2022

Transition metal sulfide materials have emerged as a new anode material for Li secondary batteries owing to their high capacity and rate capability facilitated by fast Li-ion transport through the layered structure. Among these materials, niobium disulfide (NbS₂) has attracted much attention with its high electrical conductivity and high theoretical capacity (683 mAh g^-1). In this study, we propose a facile synthesis of Fe_xNbS₂/C composite via simple ball milling and heat treatment. The starting materials of FeS and Nb were reacted in the first milling step and transformed into an Fe-Nb-S composite. In the second milling step, activated carbon was incorporated and the sulfide was crystallized into Fe_xNbS₂ by heat treatment. The prepared materials were characterized by X-ray diffraction, electron spectroscopies, and X-ray photoelectron spectroscopy. The electrochemical test results reveal that the synthesized Fe_xNbS₂/C composite electrode demonstrates a high reversible capacity of more than 600 mAh g^-1, stable cycling stability, and excellent rate performance for Li-ion battery anodes.

• 약학회지
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• 제40권6호
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• pp.727-733
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• 1996

2-(Allylthio)pyrazine is effective in selectively suppressing constitutive and inducible expression of cytochrome P450 2E1. The effect of 2-(allylthio)pyrazine against potentiat ed chemical injury was studied in rats. Vitamin-A pretreatment of rats substantially increased carbon tetrachloride hepatotoxicity, as supported by an ~4-fold increase in serum alanine aminotransferase (ALT) activity. Concomitant pretreatment of rats with 2-(allylthio)pyrazine at the daily dose of 200mg/kg resulted in a 76% decrease in vitamin-A-potentiated hepatotoxicity, which supported the possibility that 2-(allylthio)pyrazine protects the liver against chemical-induced hepatic injury by the mechanism associated with Kupffer cell inactivation. Pyridine pretreatment caused substantial enhancement in carbon tetrachloride hepatotoxicity. 2-(Allylthio)pyrazine treatment of rats reduced the pyridine-potentiated toxicity in a dose-dependent manner. Animals treated with both pyridine and 2-(allylthio)pyrazine prior to intoxicating dose of CCl$_4$ resulted in 85% and 47% decreases in pyridine-increased triglycerides and cholesterol levels in the liver. The protective effect of 2-(allylthio)pyrazine on the DNA strand breakage induced by benzenetriol was assessed by measuring the conversion of supercoiled ${\Phi}x$-174 DNA to the open relaxed form. 2-(Allylthio)pyrazine blocked the benzenetriol-induced conversion of supercoiled DNA to open circular form in a dose-dependent manner. The presence of 2-(allylthio)pyrazine at the doses from I to 10mM in the incubation mixture containing 5 ${\mu}$M benzenetriol completely protected benzenetriol-induced DNA strand breakage with the EC50 for the 2-(allylthio)pyrazine blocking being noted as ~220 ${\mu}$M, whereas allyl disulfide exerted protecting effect at relatively high concentrations (i.e. ~850 ${\mu}$M), suggesting that 2-(allylthio)pyrazine effectively scavenges the reactive oxygen species. These results provide evidence that 2-(allylthio)pyrazine blocks vitamin A- or pyridine-potentiated CCl$_4$ hepatotoxicity and that the agent is active in protecting DNA by scavenging the reactive oxygen species.

• Journal of Microbiology and Biotechnology
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• 제27권12호
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• pp.2190-2198
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• 2017

Thermoactinomyces sp. strain YT06 was isolated from poultry compost and observed to degrade integral chicken feathers completely at $60^{\circ}C$, resulting in the formation of 3.24 mg/ml of free amino acids from 50 ml of culture containing 10 g/l chicken feathers. Strain YT06 could grow and secrete keratinase using feather as the only carbon and nitrogen sources without other supplement, but complementation of 10 g/l sucrose and 4 g/l $NaNO_3$ increased the production of the keratinolytic enzyme. The maximum protease activity obtained was 110 U/ml and for keratinase was 42 U/ml. The keratinase maintained active status over a broad pH (pH 8-11) and temperature ($60-75^{\circ}C$). It was inhibited by serine protease inhibitors and most metal ions; however, it could be stimulated by $Mn^{2+}$ and the surfactant Tween-20. A reductive agent (${\beta}$-mercaptoethanol) was observed to cleave the disulfide bond of keratin and improve the access of the enzyme to the keratinaceous substrate. Zymogram analysis showed that strain YT06 primarily secreted keratinase with a molecular mass of approximately 35 kDa. The active band was assessed by MALDI-TOF mass spectrometry and was observed to be completely identical to an alkaline serine protease from Thermoactinomyces sp. Gus2-1. Thermoactinomyces sp. strain YT06 shows great potential as a novel candidate in enzymatic processing of hard-to-degrade proteins into high-value products, such as keratinous wastes.

• Bulletin of the Korean Chemical Society
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• 제24권8호
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• pp.1181-1187
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• 2003

Condensation of 4-cyano-5,6-dimethyl-3-pyridazinone 1 with aromatic aldehydes gave the novel styryl derivatives 2a-c. Refluxing of compound 2a with phosphorus oxychloride furnished 3-chloropyridazine derivative 3. Compound 3 was reacted with thiourea and produced pyridazine-3(2H)thione 4. Thieno[2,3-c]- pyridazines 5a-e were achieved by cycloalkylation of compound 4 with halocompounds in methanol under reflux and in the presence of sodium methoxide. Also, refluxing of compound 4 with N-substituted chloroacetamide in the presence of potassium carbonate afforded thienopyridazines 6a-e. Cyclization of compound 6 with some electrophilic reagents as carbon disulfide and triethyl orthoformate furnished the novel pyrimido[4',5':4,5]thieno[2,3-c]pyridazines 12 and 13a-c, respectively. Diazotisation of compound 6 with sodium nitrite in acetic acid produced the pyridazino[4',3':4,5]thieno[3,2-d][1,2,3]triazines 14a-c. Ternary condensation of compound 1, aromatic aldehydes and malononitrile in ethanol containing piperidine under reflux afforded the novel phthalazines 16a-c. Compound 3 was subjected to some nucleophilic substitution reactions with amines and sodium azide and formed the aminopyridazines 17a, b and tetrazolo[1,5-b]-pyridazine 19, respectively. The structures of the synthesized compounds were established by elemental and spectral analyses.

• 한국대기환경학회지
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• 제23권1호
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• pp.39-49
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• 2007

In this study, the performance characteristics of solid phase microextraction (SPME) were investigated for three major odorous groups that consist of 10 individual compounds ([1] volatile organic compounds (VOC): benzene, toluene, p-xylene and styrene, [2] reduced sulfur compounds (RSC): hydrogen sulfide, methyl mercaptan, dimethylsulfide (DMS), dimethyldisulfide (DMDS), and carbon disulfide, and [3] amine: trimethylamine (TMA)). For the purpose of a comparative analysis, two types of SPME fiber ([1] polidimethylsiloxane/divinilbenzene (P/D) and [2] $Carboxen^{TM}$/polidimethylsiloxane (C/P)) were test ε d against each other for a series of standards prepared at different concentration levels (100, 200, and 500 ppb). To compare the analytical performance of each fiber, all standards were analyzed for the acquisition of calibration data sets for each compound. The results of P/D fiber generally showed that its calibration slope increased as a function of molecular weight across different VOCs; however, those of C/P fiber showed a fairly reversed trend. Besides, we confirmed that the application of SPME is limited to many sulfur compounds; only two compounds (DMS and DMDS) are sensitive enough to draw calibration results out of SPME. The calibration data for RSC show generally enhanced slop values for C/P relative to P/D fiber. However, in the case of TMA, we were not able to find a notable difference in their performance.