• 공업화학
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• 제17권3호
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• pp.310-316
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• 2006

본 연구에서는 수중 악취의 원인 물질인 용존 암모니아를 제거하기 위해 분말형태의 활성탄을 사용하였다. 특히, 일반적인 분말활성탄은 암모니아 흡착능이 좋지 않기 때문에 흡착능을 높이기 위해 분말활성탄의 표면을 산 용액으로 함침시킨 산 첨착활성탄을 제조하였다. 이렇게 제조한 산 첨착활성탄을 섬유 재질로 된 다공성 지지막($10{\sim}50{\mu}m$)의 표면에 압력에 의한 분리 활성 여과 층을 형성시켜 흡착과 분리를 동시에 할 수 있는 혼합 공정을 구성하였다. 그 결과 혼합공정에서 암모니아 제거율이 60% 이상 되어, 일반 분말활성탄에 비해 10~15% 더 높은 흡착능을 보였다. 그리고 층이 형성된 동적막의 순수투과성능 실험을 보면 수투과도는 400~700 LMH로 정밀여과(Microfiltration)막 수준의 역할을 한다. 이는 수처리에서 기존의 분리막 공정보다 고효율적인 처리 유량을 유지하는 효과가 기대된다.

• 대한화학회지
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• 제28권6호
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• pp.366-373
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• 1984

기질의 치환기가 Y이고 이탈기의 치환기가 Z인 치환된 벤질 벤젠술포네이트 유도체들의 가용매-분해반응 속도를 MeOH-MeCN 혼합용매에서 측정하였다. 결과로 부터 본 반응은 전이 상태에서 기질-이탈기 사이의 결합파괴가 친핵체-기질 사이의 결합형성보다 우세한 dissociative $S_N2$ 메카니즘으로 진행됨을 알 수 있었다. 복합 Hammett 관계 분석에서 상호작용항 ${\rho}_{YZ}$가 작은 것으로 부터 본 반응에서는 기질 및 이탈기의 치환기 사이에 직접적인 상호작용이 중요하지 않음을 알 수 있었으며 이는 본 반응이 dissociative $S_N2 $반응임을 뒷받침해주는 것으로 설명할 수 있었다. 전이 상태 변화에 대한 QM해석 방법은 실험 결과와 잘 일치됨을 알 수 있었으며 PES모형 해석에 의해서는 이탈기 효과를 고려함에 있어 실험결과와 일치되지 않는 면이 있음을 알 수 있었다.

• Tribology and Lubricants
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• 제31권6호
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• pp.258-263
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• 2015

Biodiesel is an environmentally-friendly fuel with low smoke emission because it contains about 10% oxygen. Biodiesel fuel prepared by transesterification of vegetable oil or animal fats is susceptible to auto-oxidation. The rate of auto-oxidation depends on the number of methylene double bonds contained within the fatty acid methyl or ethyl ester groups. Biodiesel may be easily oxidized under several conditions, i.e., upon exposure to sunlight, temperature, oxygen environment. Maintenance of the fuel quality of biodiesel requires the development of technologies to increase the resistance of biodiesel to oxidation. Treatment with antioxidants is a promising approach for extending the shelf-life or storage time of biodiesel. The chemical properties of various amine-based antioxidants were evaluated after synthesis of the antioxidants by condensation of phenylenediamine with alkylamines at room temperature. In general, the oxidative stability can be assessed based on various experimental parameters. Such parameters may include temperature, pressure, and the flow rate of air through the samples. The Rancimat method (EN14112) was selected because it is a rapid technique that requires very little sample and provides good precision for oxidative degradation analysis. Specifically, the EN 14112 technique provides enhanced efficiency for oxidative stability evaluation when a larger ester head group is utilized. Therefore, this technique was employed for evaluation of the oxidation stability of biodiesel by the Rancimat method (EN14112).

• Bulletin of the Korean Chemical Society
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• 제15권10호
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• pp.873-881
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• 1994

The approximate rate and stoichiometry of the reaction of excess diisobutylaluminum hydride-dimethyl sulfide complex($DIBAH-SMe_2$) with organic compounds containing representative functional group under standardized conditions (toluene, $0{\circ}C$) were examined in order to define the reducing characterstics of the reagent and to compare the reducing power with DIBAH itself. In general, the reducing action of the complex is similar to that of DIBAH. However, the reducing power of the complex is weaker than that of DIBAH. All of the active hydrogen compounds including alcohols, amines, and thiols evolve hydrogen slowly. Aldehydes and ketones are reduced readily and quantitatively to give the corresponding alcohols. However, $DIBAH-SMe_2$ reduces carboxylic acids at a faster rate than DIBAH alone to the corresponding alcohols with a partial evolution of hydrogen. Similarly, acid chlorides, esters, and epoxides are readily reduced to the corresponding alcohols, but the reduction rate is much slower than that of DIBAH alone. Both primary aliphatic and aromatic amides examined evolve 1 equiv of hydrogen rapidly and are reduced slowly to the amines. Tertiary amides readily utilize 2 equiv of hydride for reduction. Nitriles consume 1 equiv of hydride rapidly but further hydride uptake is quite slow. Nitro compounds, azobenzene, and azoxybenzene are reduced moderately. Cyclohexanone oxime liberates ca. 0.8 equiv of hydrogen rapidly and is reduced to the N-hydroxylamine stage. Phenyl isocyanate is rapidly reduced to the imine stage, but further hydride uptake is quite sluggish. Pyridine reacts at a moderate rate with an uptake of one hydride in 48 h, while pyridine N-oxide reacts rapidly with consumption of 2 equiv of hydride for reduction in 6h. Similarly, disulfides and sulfoxide are readily reduced, whereas sulfide, sulfone, and sulfonic acid are inert to this reagent under these reaction conditions.

• 분석과학
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• 제34권3호
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• pp.115-121
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• 2021

에탄올 대사체인 에틸글루쿠로나이드(ethyl glucuronide, EtG)와 에틸설페이트(ethyl sulfate, EtS)는 에탄올 섭취의 직접적인 지표물질로서 여러 생체 시료에서 법과학적으로 다양하게 연구되고 있다. 부검 변사자에게서 검출된 에탄올이 사망 전 음주에 의한 것인지 사후 부패에 의해 생성된 에탄올인지 판단하기 위해서는 에탄올 대사체를 분석할 필요가 있다. 일반적으로 혈액에서 에탄올과 함께 EtG, EtS를 검출하고 있지만 부패 상황에 따라 혈액을 확보하는 것이 어려우므로 조직 생체시료를 이용해 에탄올 대사체를 검출함으로써 이를 대체해야 한다. 본 연구에서는 조직 중에서 비장을 선택하여 LC-MS/MS를 이용해 EtG, EtS를 검출하였으며 시험법이 적합한 방법인지를 증명하기 위해 밸리데이션을 수행하여 법과학적 감정에 사용할 수 있는 분석법을 완성하고 실제 부검 사례에 적용하였다.

• Bulletin of the Korean Chemical Society
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• 제23권1호
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• pp.65-70
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• 2002

We have evaluated the specific hydroxyl group-solvent and carbonyl group-solvent interactions by using an Alltima C18 stationary phase and by measuring the retention data of carefully selected solutes in 60/40, 70/30, and 80/20(v/v%) acetonitrile/water eluents at 25, 30, 35, 40, 45, and 50 oC. The selected solutes are phenol, acetophenone, alkylbenznes(benzene to hexylbenznene), 4 positional isomers of phenylbutanol, 5-phenyl-1-pentanol, 3 positional isomers of alkylarylketone derived from butylbenzene, and 1-phenyl-2-hexanone. The magnitudes of hydroxyl group-acetonitrile/water specific interaction enthalpies are larger than those of carbonyl group-acetonitrile/water specific interaction enthalpies in general while the magnitudes of carbonyl group-methanol/water specific interaction enthalpies are larger than those of hydroxyl group-methanol/water specific interactions. We observed clear discrepancies in functional group-solvent specific interaction among positional isomers. The variation trends of solute transfer enthalpies and entropies with mobile phase composition in the acetonitrile/water system are much different from those in the methanol/water system. The well-known pocket formation of acetonitrile in aqueous acetonitrile mixtures has proven to be useful to explain such phenomena.

• Bulletin of the Korean Chemical Society
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• 제34권6호
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• pp.1722-1726
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• 2013

A kinetic study on nucleophilic substitution reactions of phenyl Y-substituted-phenyl carbonates (5a-5j) with ethylamine in 80 mol % $H_2O$/20 mol % DMSO at $25.0{\pm}0.1^{\circ}C$ is reported. The plots of $k_{obsd}$ vs. [amine] are linear for the reactions of substrates possessing a strong electron-withdrawing group (EWG) but curve upward for those of substrates bearing a weak EWG, indicating that the electronic nature of the substituent Y in the leaving group governs the reaction mechanism. The reactions have been concluded to proceed through a stepwise mechanism with one or two intermediates (a zwitterionic tetrahedral intermediate $T^{\pm}$ and its deprotonated form $T^-$) depending on the nature of the substituent Y. Analysis of Bronsted-type plots and dissection of $k_{obsd}$ into microscopic rate constants have revealed that the reactions of substrates possessing a strong EWG (e.g., 5a-5f) proceed through $T^{\pm}$ with its formation being the rate-determining step, while those of substrates bearing a weak EWG (e.g., 5g-5j) proceed through $T^{\pm}$ and $T^-$.

• Bulletin of the Korean Chemical Society
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• 제23권2호
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• pp.253-261
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• 2002

Vibrational properties of ferrocyanide complex ion, $[Fe(CN)_6]^{4-}$ , have been studied based on the force constants obtained from the density functional calculations at B3LYP/$6-31G^{\ast\ast}$ level by means of the normal mode analysis using new bond angle and linear angle internal coordinates recently developed. Vibrations of ferrocyanide were manipulated by twenty-three symmetry force constants. The angled bending deformations of C-Fe-C, the linear bending deformations of Fe-C${\equiv}$N and the stretching vibrations of Fe-C have been quantitatively assigned to the calculated frequencies. The force constants in the internal coordinates employed in the modified Urey-Bradley type potential were evaluated on the density functional force field applied, and better interaction force constants in the internal coordinates have been proposed. The valence force constants in the general quadratic valence force field were also given. The stretch-stretch interaction and stretch-bending interaction constants are not sensitive to the geometrical displacement in the valence force field.

• 한국수정란이식학회지
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• 제29권2호
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• pp.119-125
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• 2014

Although the majority of surviving pigs cloned by somatic cell nuclear transfer (SCNT) appear to be physiologically normal, there is a general lack of detailed hemato-physiologic studies for the period of early adulthood to substantiate this claim. In the present study, we investigated variation in blood chemistry and endocrinological parameters between mesenchymal stem cells (MSCs) derived from cloned and normal age-matched female and male miniature pigs. Cloned females and males showed normal ranges for complete blood count assessments. Biochemical assessments showed that ${\gamma}$-GGT, ALT and cholesterol levels of male and female clones were significantly (P<0.05 or P<0.01, respectively) higher than that of age-matched control miniature pigs. Variations in insulin and IGF-1 were higher in female clones than in male clones and controls. Thus, although female and male cloned miniature pigs may be physiologically similar to normal animals, or at least within normal ranges, a greater degree of physiological and endocrinological variation was found in cloned pigs. The above variation must be taken into account before considering cloned female or male miniature pigs for various biomedical applications.

• 한국응용과학기술학회지
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• 제24권2호
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• pp.109-116
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• 2007

2-Chlorobenzoyl hydrazine refluxed with benzoyl isothiocyanate and phenyl isothiocyanate in ethanol for 3 hours to give benzamide derivative (1) and anilinederivative (2) on yield of 71%and 95%, respectively. Benzamide derivative (1) reacted with ethanolic sodium hydroxide on reflux to afford cyclization product (3), followed by general substitution reaction of two steps to give acetamide (5), and derivatived acetamides 7a-7k, while aniline derivative (2) reacted with ethanolic sodium hydroxide on reflux to afford another cyclization product (4). Thiol (4) reacted with N-phenyl chloroacetamide in the presence of potassim carbonate to give acetamide derivative (6). Compounds 1-7kwere evaluated for their growth inhibition against five cancer cell lines, including human lung carcinoma (A-549), human prostate cancer (DU145), human colon adenocarcinoma (HT-29), human malignant melanoma (SK-MEL-2) and human ovary malignant ascites (SK-OV-3) with sulforhodamine B (SRB) assay. All compounds (1-7k) showed low inhibition activities under 50% on 100M concentration.