• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.36-36
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• 2010

Low-pressure fluorocarbon plasmas are widely used in microelectronics fabrication for a variety of surface modification purposes. In particular, fluorocarbon plasmas are used for the etching of dielectrics such as silicon dioxide and silicon nitride. Among the various fluorocarbons, this study focuses on C4F6 molecules (C4F6s) which are composed of hexafluorocyclobutene (c-C4F6), hexafluoro-1, 3-butadiene (1, 3-C4F6), and hexafluoro-2-butyne (2-C4F6). We have investigated the dissociation reactions of C4F6s, resulting in CF2, CF3, C2F3, and C3F3 fragments, by using the wB97X-D functional with various basis sets. In this presentation, the geometrical properties, energetics, and dissociation mechanisms of C4F6s will be suggested.

• Mass Spectrometry Letters
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• 제4권4호
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• pp.71-74
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• 2013

In the present study, we report that the charge-directed (assisted) peptide dissociation products, such as b- and y-type peptide backbone fragments, were the major products in MS/MS and $MS^3$ applications of some o-TEMPO-Bz-C(O)-peptide ions, while radical-driven dissociation products, such as a/x and c/z-type fragments, were previously shown to be the major products in the free radical initiated peptide sequencing mass spectrometry (FRIPS MS). Those o-TEMPO-Bz-C(O)-peptides share a common feature in their sequences, that is, the peptides do not include an arginine residue that has the highest proton affinity among free amino acids. The appearance of b- and y-type fragments as major products in FRIPS MS can be understood in terms of the so-called "mobile-proton model". When the proton is highly mobilized by the absence of arginine, the chare-directed peptide dissociation pathways appear to be more competitive than the radical-driven dissociation pathways, in our FRIPS experiments.

• 생명과학회지
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• 제8권1호
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• pp.60-66
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• 1998

G- 및 C-banding법에 의한 ICR 생쥐의 유사분열과 감수분열 시기의 염색체 특징에 관하여 조사하였다. 이를 위한 염색체 표본 작성은 Imai et al.의 공기건조법을 다소 변형한 방법에 의하였다. 정소를 이용한 염색체 분석은 유사분열뿐만 아니라 감수분열단계들을 모두 관찰할 수 있었으며, C-banding에 의하여 X 염색체를 포함한 모든 염색체의 돈원체 부위가 강하게 염색되었다. 정상의 제 1 감수분열 전기와 중기 사이의 세포들에서 2가 염색체로 된 19쌍의 상염색체과 1개의 말단결합으로 된X-Y 염색체를 관찰할 수 있었다. 대조군의 제 1 정모세포에서 조기분리된 성염색체를 가지는 세포의 빈도는 약 7.45%였으나,alkylating agents 처리군에서는 대조군에서보다 약 3-4배 이상 높에 나타났다. 그리고 감수분열 단계의 염색체 표본에 C-banding을 적용함으로서 X-Y 염색체 조기분리의 관찰이 매우 용이하였다.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 1996년도 봄 학술발표회 초록집
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• pp.51-51
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• 1996

• 대한화학회지
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• 제42권4호
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• pp.369-377
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• 1998

이소옥사졸과 그의 유도체가 배위된 팔라듐(II) 및 백금(II)착물$([M(L)_2X_2]$, M=Pd(II), Pt(II); L=isoxazole(isox), 3,5-dimethylisoxazole(3,5-diMeisox), 3-methyl, 5-phenylisoxazole(3-Me, 5-Phisox), and 4-am-ino 3,5-dimethylisoxazole(4-ADI); X=Cl, Br)의 항암활성을 분자역학(MM2)법으로 최소에너지를 갖는 구조를 구한 후 확장분자궤도함수(EHMO)법으로 조사하였다. 중심금속의 $d_x^{2-}_y^2$ 궤도함수와 할로겐 원자의 $p_x$ 궤도함수 사이의 ${\sigma}MO$ 에너지준위$(E_{{\sigma}(Pd,Pt-X)})$가 질소원자의 $p_x$ 궤도함수 사이의 ${\sigma}MO$ 에너지준위 $(E_{\sigma}(Pd,Pt-N))$보다 예외없이 더 높아서 결합이 약함을 알 수 있었다. 아울러 같은 착물에서 cis- 보다 trans-착물에서 $(E_{\sigma}(Pd,Pt-X))$ 값이 더 높아서 결합이 약함을 알았다. 또한 평면형 리간드가 배위될 경우 cis-, trans- 이성체 모두 백금착물에서보다 팔라듐착물에서 $X^-$ 이온의 이탈이 더 용이했다. 다라서 $X^-$ 이온으로 떨어져 나가는 용이성이 항암활성과 어떤 관계가 있을 것으로 생각하고 $E_{{\sigma}(Pd,Pt-N)}-E_{{\sigma}(Pd,Pt-X)}({\Delta}E_{{\sigma}(N-X)})$과 저해활성 계수인 logIA의 값를 도시하였던바 실험치와 상관 계수가 0.96인 좋은 직선성이 성립함을 알 수 있었다.

• 천문학회지
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• 제29권spc1호
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• pp.345-346
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• 1996

The contrasting values of the oscillator strengths for the (0,0) band of SiH+ molecules for the $A\;^1II-X\;^1{\sum}+$ transition reported in literature, motivated us to reinvestigate the same with the help of a new set of well accepted solar photospheric models, elemental abundances and dissociation energy.

• 대한화학회지
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• 제39권4호
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• pp.244-251
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• 1995

이소옥사졸과 그의 유도체를 가진 팔라듐(II) 착물 $[Pd(L)_2X_2]$, L=isoxazole(isox), 3,5-dimethylisoxazole(3,5-diMeisox), 3-methyl, 5-phenylisoxazole(3-Me, 5-Phisox), and 4-amino, 3,5-dimethylisoxazole(4-ADI); X=Cl, Br)의 항암활성을 확장분자궤도함수(EHMO)법으로 조사하였다. X 원자의 알짜전하 값은 trans-이성체가 cis-이성체보다 음의 값으로 대체로 크게 나타났고, X=Cl일 때가 X=Br일 때보다 음의 값으로 커서, Cl일 때가 이탈이 용이함을 알 수 있었다. Pd(dx2-y2)-X(px)의 ${\sigma}MO$ 에너지($E{\sigma}(Pd-X)$)가 Pd(dx2-y2)-N(px)의 ${\sigma}MO$ 에너지 ($E{\sigma}(Pd-N)$)보다 예외없이 더 높아서 결합이 약함을 알았다. 아울러 같은 착물에서 cis-보다 trans-착물에서 ${\sigma}(Pd-X)$값이 더 높아서 결합이 약함을 알았다. 따라서 $X^-$ 이온으로 떨어져 나가는 용이성과 그 구조변화가 항암활성과 관계가 있을 것으로 생각하고 $E{\sigma}(N-X)(E{\sigma}(Pd-N)－E{\sigma}(Pd-X))$값과 저해활성 계수인 logIA의 값을 도시하였던 바 실험치와 상관 계수가 0.96안 좋은 직선성이 성립함을 알았다.

• Bulletin of the Korean Chemical Society
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• 제34권5호
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• pp.1401-1406
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• 2013

This study tested the feasibility of observing H/D exchange of intact protein by top-down electron capture dissociation (ECD) mass spectrometry for the investigation of protein structure. Ubiquitin is selected as a model system. Local structural information was obtained from the deuteration levels of c and $z^{\cdot}$ ions generated from ECD. Our results showed that ${\alpha}$-helix region has the lowest deuteration level and the C-terminal fraction containing a highly mobile tail has the highest deuteration level, which correlates well with previous X-Ray and HDX/NMR analyses. We studied site-specific H/D exchange kinetics by monitoring H/D exchange rate of several structural motives of ubiquitin. Two hydrogen bonded ${\beta}$-strands showed similar HDX rates. However, the outer ${\beta}$-strand always has higher deuteration level than the inner ${\beta}$-strand. The HDX rate of the turn structure (residues 8-11) is lower than that of ${\beta}$-strands (residues 1-7 and residues 12-17) it connects. Although isotopic distribution gets broader after H/D exchange which results in a limited number of backbone cleavage sites detected, our results demonstrate that this method can provide valuable detailed structural information of proteins. This approach should also be suitable for the structural investigation of other unknown proteins, protein conformational changes, as well as protein-protein interactions and dynamics.

• Archives of Pharmacal Research
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• 제19권6호
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• pp.502-506
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• 1996

Protein X is one of the subunits of pyruvate dehydrogenase complex. The biological role of this protein has not been fully elucidated, mainly because of the difficulty in its dissociation from the tightly bound dihydrolipoamide acetyltransferase-protein X subcomplex. We have found that the detachment of protein X from acetyltransferase subunit can be easily accomplished by the cycles of freezing and thawing proces. Several lines of evidence including sodium dodecyl sulfate-polyacrylamide gel electrophoresis, N-terminal amino acid sequence analysis and acetylation with $[2^{14}C]$ pyruvate confirmed that the purified protein is protein X. The purified intact form of protein X was acetylated by $[2^{14}C]$ pyruvate in the presence of py-ruvate dehydrogenase subunit.The acetylation efficiency of this protein was lower than that of acetyltransferase and was not affected by the presence of acetyltransferase.

• Bulletin of the Korean Chemical Society
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• 제30권7호
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• pp.1470-1474
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• 2009

Thermal and photochemistry of methyl iodide ($CH_3I)\;adsorbed\;on\;D_2O$ ice film on Cu(111) at 100 K were studied using temperature-programmed desorption (TPD) time-of-flight mass spectrometry (TOF-MS), X-ray and ultraviolet photoelectron spectroscopies. On the basis of TPD, multilayer and monolayer $CH_3I$ molecules desorb from $D_2O$ ice layer at 120 and 130 K, respectively. Photo-irradiation at 100 K exhibits dramatic changes in the TPD and I $3d_{5/2}\;XPS\;of\;CH_3I$ on ice film, due to a dramatic dissociation of $CH_3I$. The dissociation is likely activated by solvated electrons transferred from the metal substrate during photo-irradiation. No other photo-initiated reaction products were found within our instrumental detection limit. During photo-irradiation, the $CH_3I$, $CH_3$ and I could be trapped (or solvated) in ice film by rearrangement (and self-diffusion) of water molecules. A newly appeared parent molecular desorption peak at 145 K is attributed to trapped $CH_3I$. In addition, the $CH_3$ and I may diffuse through ice and chemisorb on Cu(111), indicated by TPD and I $d_{5/2}$ XPS taken with photo-irradiation time, respectively. No molecular ejection was found during photo-irradiation at 100 K. The work functions for $CH_3I/Cu(111),\;D_2O/Cu(111)\;and\;CH_3I/D_2$O/Cu(111) were all measured to be about 3.9 eV, 1.0 eV downward shift from that of clean Cu(111).