• Bulletin of the Korean Chemical Society
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• 제18권1호
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• pp.27-32
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• 1997

The geometries and energies of the isomers in alkyne complexes MCl(PH3)2(η2-C2H2), M=Rh and Ir, are theoretically investigated using ab initio methods at the Hartree-Fock and up to MP4 level of theory and relativistic effective core potentials for Rh and Ir metals. The optimized structures of Rh complexes, 1-3 at MP2/ECP1 level are in good agreement with the related experimental data. The binding energies of C2H2 to d8-metal fragments are computed to be ∼55 kcal/mol. The vinylidene complexes for Rh and Ir metals are calculated to be much lower in energy than the alkyne complexes. The alkyne-vinylidene rearrangement is possible to proceed exothermically through the intermediate hydrido-alkynyl complexes, 2 or 9. Detailed comparison is given about the geometries and relative energies on Rh and Ir isomers at the various level ab initio calculations with orbital analysis.

• 한국통신학회논문지
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• 제31권1C호
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• pp.87-92
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• 2006

[ $AB^2$ ]연산은 공개키 암호화 시스템을 위한 효율적인 기본 연산으로 알려져 있고 이를 위한 다양한 하드웨어가 설계되었다. 그러나 이들 구조들은 암호학적 응용에 사용되기에는 구조복잡도가 크다는 문제점이 있었다. 본 논문에서는 GF($2^m$)상에서 공간 효율적인 분할된 $AB^2$ 시스톨릭 모듈러 곱셈기를 설계한다. MSB $AB^2$ 모듈러 곱셈 알고리즘으로부터 데이터 의존 그래프를 유도하고 유도된 의존 그래프를 1/3로 분할함으로서 공간 효율적인 분할된 $AB^2$ 시스톨릭 곱셈기를 설계한다. 본 논문에서 제안한 곱셈기는 기존의 곱셈기와 비교하여 2/3정도의 구조 복잡도를 줄일 수 있다. 본 논문에서 제안한 구조는 크기에 제한을 갖는 스마트 카드 등에서 사용될 공개키 암호의 핵심이 되는 지수기의 구현을 위한 효율적인 기본구조로 사용될 수 있을 것이다.

• 대한금속재료학회지
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• 제50권3호
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• pp.256-262
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• 2012

This study investigated the hydrogen storage properties of Zr-Based $AB_{2-x}M_x$ metal hybride made by HCS (Hydriding Combustion Synthesis). The materials were prepared by HCS 80 wt% $AB_2$-15 wt% Mg-5 wt% Mm, HCS 80 wt% $AB_2$-20 wt% Mg and pure Zr-Based $AB_2$, These materials were activated at 298 K under 20 bar. Both HCS 80 wt% $AB_2$-20 wt% Mg and HCS 80 wt% $AB_2$-15 wt% Mg-5 wt% Mm were absorbed within 1 minute. In the case of the $AB_2$, it was perfectly absorbed within 6 minutes. Then, the materials were evaluated to obtain P-C-T (Pressure-Composition-Temperature) curves at 298K. As a result, the hydrogen storage capacity of HCS 80 wt% $AB_2$-20 wt% Mg, HCS 80 wt% $AB_2$-15 wt% Mg-5 wt% Mm and pure Zr-Based $AB_2$ were determined to be 1.2, 1.6 and 1.74 wt%, respectively. The activation energy and rate controlling step were calculated by the Johnson-Mehl Avrami equation. The activation energies of HCS 80 wt% $AB_2$-20 wt% Mg, HCS 80 wt% $AB_2$-15 wt% Mg-5 wt% Mm and pure Zr-Based $AB_2$ were 26.91, 20.45, and 60.41 kJ/mol, respectively. Also, the values of ${\eta}$ in the Johnson-Mehl Avrami equation for HCS 80 wt% $AB_2$-20 wt% Mg, HCS 80 wt% $AB_2$-15 wt% Mg-5 wt% Mm and pure Zr-Based $AB_2$ are 0.60, 0.51, and 0.44. So, the rate controlling steps which indicate hydrogen storage mechanism are an one dimensional diffusion process.

• Asian-Australasian Journal of Animal Sciences
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• 제16권8호
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• pp.1212-1217
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• 2003

Fifty-two Holstein cows with different phenotypes of $\kappa$-casein ($\kappa$-CN) and $\beta$-lactoglobulin ($\beta$-LG) were selected to provide weekly milk samples for heating at 30, 70, 75 and $80^{\circ}C$ for 2 min. Coagulating properties of heated milk samples measured as rennet clotting time, rate of curd firming and curd firmness at cutting were determined by a Formagraph. Milk samples were analysed for fat and casein. Least squares analyses of data, after adjustments were made for effect of milk casein and fat contents, indicated that although an increase in heating temperatures resulted in less desirable coagulating properties, the effect of milk types was inherent irrespective of heating temperatures. The shortest rennet clotting time (6.06 min), fastest rate of curd firming (5.61 min) and firmest curd (38.05 mm) were obtained from milk with the B variant for $\kappa$-CN and B variant for $\beta$ -LG when preheated at $30^{\circ}C$. It appears that milk bearing $\kappa$-CN B is more resistant to heat perturbation. All milk samples having the $\kappa$-casein AA (milk types AA/AA, AA/AB, AA/BB) did not have a measurable K20 value when preheated at $70^{\circ}C$. This effect was observed for $\kappa$-casein AB (milk types AB/AA, AB/AB, AB/BB) at $75^{\circ}C$ and $\kappa$-casein BB (milk types BB/AA, BB/AB, BB/BB) at $80^{\circ}C$.

• 한국결정학회지
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• 제2권1호
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• pp.27-31
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• 1991

반경험적인 Tersoff 포텐셜을 사용한 lattice statics 시뮬레이션 테크닉에 의하여 C24와 C60 fullerenes의 구조와 에너지를 구하였다. 그 결과는 ab initio 계산 결과와 잘 일치 하였다.

• Biomolecules & Therapeutics
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• 제31권6호
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• pp.611-618
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• 2023

Rhizome of Alisma orientale has been used as a traditional medicine for treating kidney diseases in East Asian countries. Its inhibitory effects on hypersensitivity responses have been reported for methanol extracts, with alisol B 23-acetate (AB23Ac) being the most active constituent among six terpenes in inhibiting the direct passive Arthus reaction. However, whether AB23Ac has efficacy against allergic asthma has not been tested to date. The in vivo efficacy of AB23Ac in an ovalbumin (OVA)-induced allergic asthma mouse model was evaluated by administrating AB23Ac before OVA sensitization or OVA challenge in BALB/c mice. AB23Ac suppressed antigen-induced degranulation of RBL-2H3 mast cells in a concentration-dependent manner. The administration of AB23Ac both before OVA sensitization and OVA challenge greatly lowered pulmonary resistance and the increase in immune cell counts and inflammatory responses around the peribronchial and perivascular regions. In addition, the inflammatory cytokine levels of Th1/Th2/Th17 cells in the bronchoalveolar lavage fluid decreased in the AB23Ac-treated groups. AB23Ac reduced the number of PAS-stained cells in the lungs. Furthermore, a computer modeling study indicated that AB23Ac can bind tightly to spleen tyrosine kinase (Syk). These results suggest that AB23Ac may ameliorate allergic asthma by suppressing immune responses in dendritic cells during sensitization and in mast cells during challenge periods.

• Bulletin of the Korean Chemical Society
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• 제23권2호
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• pp.241-244
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• 2002

Using ab initio method, we have studied the structural stabilities, the electronic structures and properties between the two isomers with $C_{2h}$ and $C_{2v}$ symmetry of AlN four-membered-ring single precursors $[Me_2AlNHR]_2$ (R = Me, $^iPr$, and $^iBu$). In the viewpoint of bond lengths in optimized structures, the N-C bonds are considerably affected by the change of the R groups bonded to nitrogen, but the bonding characters of the Al-N and Al-C bonds are little affected. Also the structural stabilities between the two isomers with $C_{2h}$ and $C_{2v}$ symmetry by using Hartree-Fock (HF) and the second order Moeller-Pleset (MP2) calculations agree well with the experimental results for the relative stability of bis(dimethyl- m-isopropylamido-aluminum) (BDPA) and bis(dimethyl- m-t-butylamido-aluminum) (BDBA), while the semiempirical AM1 and PM3 calculations for BDPA were reverse. Thus, our results may aid in designing an optimum precursor for a given process by explaining the experimental results through the elimination of the R groups bonded to nitrogen.

• 대한화학회지
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• 제50권4호
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• pp.291-297
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• 2006

Cyclopropyl 링과 할로겐 원소가 결합된 붕소원자 사이의 hyperconjugation 효과를 알아보기 위하여 CPDFB와 CPCFB 분자의 여러 conformation과 transition state 구조들에 대해 DFT와 ab initio 방법을 사용하여 다양한 레벨에서 구조최적화 및 NBO 분석을 수행하였다. 그 결과 주요 상호작용 형태는 화합물에 따라 단일결합 오비탈 (C1-C3, C2-C3) n* (B9) 또는 *(B9-Cl11) 오비탈로 전자를 제공하는 것이었고 이때 안정화 에너지는 CPDFB 분자의 경우 6.63 kcal/mol, CPCFB 분자의 경우는 conformation에 따라 6.97(E-form)/6.79(Z-form) kcal/mol 이었다. 또한, BF2와 BFCl 기의 내부회전에 의한 회전장벽의 크기는 각각 5.3~6.7 kcal/mol과 5.7~6.5 kcal/mol로 기존에 보고된 실험값과 잘 일치함을 보였다. 마지막으로 CPCFB 분자의 conformers 중에서 Z-form이 global minimum으로 확인되었고 E-form 보다 0.2 kcal/mol 정도 안정하였다.

• Applied Biological Chemistry
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• 제41권1호
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• pp.60-66
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• 1998

10종의 식용 버섯 자실체에 대한 항보체 활성 검색에서 가장 높은 활성을 나타낸 양송이버섯 자실체를 대상으로 항보체 활성물질의 추출조건을 조사하였다. 최적조건으로서 5% urea가 함유된 0.1 N NaOH 용액으로 $65^{\circ}C$에서 2시간동안 양송이버섯 자실체를 추출한 후 methanol 가용획분이 제거된 조다당 획분 AB-0를 얻었다. AB-0는 1 mg/ml에서 90% 이상의 높은 항보체활성을 나타내었으며 마우스에 이식된 sarcoma-180에 대하여 74%의 저지효과를 보였다. AB-0를 acetone 농도에 따른 침전 분획을 실시하여 AB-20, AB-40, AB-60, AB-80, AB-A의 5개의 획분을 얻었다. 이중 가장 높은 항보체활성과 수율을 나타낸 AB-20 획분은 탄수화물 39%, 단백질 46%를 함유하였으며, 구성당은 glucose, arabinose, xylose, galactose, mannose가 6.49 : 1.98 : 1.24 : 1.00 : 0.71의 비율로 존재하였고 구성아미노산은 isoleucine(12.60%), glutamic acid+glutamine(12.45%), valine(11.79%), alanine(11.46%), leucine(10.19%)와 aspartic acid, asparagine(10.56%) 등 이었다. Pronase 처리한 AB-20에서는 78.5%의 항보체활성을 나타내고 대조군에 비해 14.5% 감소하였으나, AB-20의 periodate 산화물에서는 활성이 42.6%로 50% 이상 크게 감소하였다. 따라서 양송이 버섯의 알칼리 추출물중 가장 강한 활성을 보인 AB-20의 주요 활성부위는 다당류이며 단백질도 일부 관여하는 것으로 생각되었다.

• 대한화학회지
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• 제39권3호
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• pp.150-156
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• 1995

Pyrazole 유도체들인 1,2,4-triazolidine-3,5-dione(1)과 1,3,4-oxa(or thia) diazolidine-2,5-dione(2,3)의 lactam-lactim tautomer들을 ab initio, AM1 그리고 PM3 방법으로 연구하였다. 세 가지 방법에서 모두 1 화합물의 가장 안정한 형태는 dilactam인 1a이고 다음으로 lactam-lactim인 2b로 결정되었댜. 계산방법에 따라 1a와 1b의 에너지 차이는 4.1~12.6kcal/mol로 계산되었다. 1a에 대한 ab initio 구조는 X-ray 구조와 잘 일치하고 있다. 2 화합물의 안정도는 2a>2b>2c인 반면 황원자를 포함하고 있는 3 화합물 tautomer들간의 안정도 순서는 계산방법에 의존된다. 3-21G에서는 3a가 3b보다 4.9kcal/mol 안정한 반면 AM1은 3b가 2.71kcal/mol 안정한 결과를 얻었다.