• 한국대기환경학회지
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• 제1권1호
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• pp.9-15
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• 1985

For the purpose of obtaining the index that represents the contaminated status due to polychlorinated biphenyls (PCB) in the human body, the authors investigated the contents of PCB in the plasma of 183 subjects who were not exposured to the massive amount of PCB occupationaly in the past. The obtained results were as follows; 1. The mean contents of PCB in plasma were 3.35 $\pm$ 1.48 ppb in male and 3.04 $\pm$ 1.06 ppb in female. $Cl_4$ and $Cl_3$ were the main isomers in both sexes. 2. The distribution of total-PCB by the age group was showed increasing tendency with the age in both sexes. 3. The tendency of freqyency distribution of total-PCB level were skewed to the higher level in malo and skewed to the lower level in female. 4. There was satistically significant interrelationship between age and total-PCB in plasma in both sexes.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.52-53
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• 2006

A new series of PEO-PPO-PEO and PPO-PEO-PPO copolymers having several hydroxyl groups on the PPO chain segment were synthesized, further modified with various poly(lactic acid) PLA oligomeric chains to confer physical stability after thermo-gelation in the body fluid. Gel stability was endowed by either increasing hydrophobic interaction between PLA chains or inducing stereocomplex formation between enatiomeric isomers of PLA chains. Macromolecular drugs were incorporated within the gels and their release patterns were investigated using Pluronic F127 as a control.

• Bulletin of the Korean Chemical Society
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• 제29권1호
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• pp.81-84
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• 2008

In the present study, we report 1H and 13C NMR data of 19 methoxyflavonol derivatives with different substitution patterns on A- and B-ring. In addition, the influence of the methoxy substituents in A- and B-ring on the 1H and 13C NMR chemical shifts is discussed: the 1H and 13C chemical shifts of and the number of methoxyl groups provided information allowing elimination of many structural isomers from consideration and in certain instances greatly simplified structural elucidation.

• Bulletin of the Korean Chemical Society
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• 제35권3호
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• pp.881-885
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• 2014

Photophysics of 10-hydroxybenzo[h]quinoline (HBQ) has been in controversy, in particular, on the nature of the electronic states before and after the excited state intramolecular proton transfer (ESIPT), even though the dynamics and mechanism of the ESIPT have been well established. We report highly time resolved fluorescence spectra over the full emission frequency regions of the enol and keto isomers and the anisotropy in time domain to determine the accurate rates of the population decay, spectral relaxation and anisotropy decay of the keto isomer. We have shown that the ~300 fs component observed frequently in ESIPT dynamics arises from the $S_2{\rightarrow}S_1$ internal conversion in the reaction product keto isomer and that the ESIPT occurs from the enol isomer in $S_1$ state to the keto isomer in $S_2$ state.

• Bulletin of the Korean Chemical Society
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• 제35권3호
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• pp.721-724
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• 2014

We have explored the potential energy surface for the dissociation of the pyridazine molecular ion using G3 model calculations. The pathways have been obtained for the formation of five possible $C_4H_4^{+{\bullet}}$ isomers by the loss of $N_2$ and the consecutive $H^{\bullet}$ loss. It is predicted that the methylenecyclopropene radical cation is the predominant product in the loss of $N_2$, which is formed via the allenylcarbene radical cation, and $CH_2=C-C{\equiv}CH^+$ is the predominant product in the consecutive $H^{\bullet}$ loss.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2007년도 제29회 추계학술대회논문집
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• pp.190-193
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• 2007

노보르나디엔의 이량화반응에 의해 제조되는 다중고리 탄화수소화합물 제조에 대한 연구결과를 설명하였다. NBD 이량체 중에서 pentacyclic exe-t-exo, hexacyclic exe-eodo, hexacyclic endo-endo 이성질체를 선택적으로 제조하기위하여 이량화 반응을 실시하였다. 각각의 이량화반응 촉매, 반응절차 그리고 분석방법이 개발되었다. 본 실험을 통하여 적당한 반응조건, 비교적 높은 이량체수율을 얻었으며, 이 반응기술은 고에너지밀도 연료 개발에 유용하게 사용될 수 있을 것이다.

• 대한화학회지
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• 제22권6호
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• pp.417-422
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• 1978

벤잘피롤린은 (Z-2, Z-4)을 직접 조사하거나 광증감제를 넣어 조사하니 광산소화되지 않고 광이성화 되었다. 단색광 (557nm)을 사용하여 광증감제인 로즈벤갈 (rose bengal)만을 들뜨게하여서 일어나는 벤잘피롤린은 (Z-2, Z-4 및 E-2)들의 이성화에서는 삼중상태의 벤잘피롤린온이 관여하였다.

• 대한화학회지
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• 제7권4호
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• pp.225-229
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• 1963

The nature of the two isomers of 4-nitroazoxybenzenes in strongly acidic solution have been analyzed by U.V. spectrophotometry. Oxygen atom in the azoxy-group of $\alpha$-and $\beta$-4-nitroazoxybenzene in strong acid solution migrates neither to para position nor ortho position of the unsubstituted benzene ring of the compound in contrast with the cases of methyl-and bromo-substituted azoxybenzene, and shown no Wallach rearrangement. Since the $^1A{\rightarrow}^1H$ bands of the spectra shown hyperchromic effect whereas the ${\pi}{\rightarrow}{\pi}^*$ bands of them exhibit extream hypochromic effect, it appears most likely that trans ${\rightarrow}$cis isomerization take place in the media. A mechanism of a triangular transition state by which the transformation might be proceeded, is proposed.

• Bulletin of the Korean Chemical Society
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• 제32권7호
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• pp.2319-2324
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• 2011

Molecular structures and chemical properties of 1-aminoimidazole derivatives have been investigated at high levels of density functional theories. Heat of formation, density, explosive performances and impact sensitivities have been estimated at the global minimum of potential energy surface. As more nitro groups are introduced, the explosive performances of 1-aminoimidazole derivatives are enhanced, while the impact sensitivity becomes more sensitive. A two-dimensional plot between explosive performance and impact sensitivity has been utilized to comprehend the technical status of new explosive candidates. Based on locations in the two-dimensional plot, 1-aminodinitroimidzole isomers appears to have a potential to be good candidates for insensitive explosives, and 1-aminotrinitroimidazole may become a powerful explosive molecule whose behavior is quite close to HMX.

• Bulletin of the Korean Chemical Society
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• 제32권7호
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• pp.2301-2305
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• 2011

The potential energy surface (PES) for the loss of HCN or HNC from the pyrazine molecular ion was determined based on quantum chemical calculations using the G3//B3LYP method. Four possible dissociation pathways to form four $C_3H_3N^{+{{\bullet}}$ isomers were examined. A Rice-Ramsperger-Kassel-Marcus quasi-equilibrium theory model calculation was performed to predict the dissociation rate constant and the product branching ratio on the basis of the obtained PES. The resultant rate constant for the HCN loss agreed with the previous experimental result. The kinetic analysis predicted that the formation of $CH=CHN{\equiv}CH^{+{\bullet}}+HCN$ was predominant, which occurred by three consecutive steps, a C-C bond cleavage to form a linear intermediate, a rearrangement to form an H-bridged intermediate, and elimination of HCN.