• Bulletin of the Korean Chemical Society
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• 제30권2호
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• pp.429-434
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• 2009

The OH($X^2{\Pi},\;{\nu}$"=0, 1) internal state distributions from the reaction of electronically ground state oxygen atoms with HSi$Cl_3$ were measured using laser-induced fluorescence. The ground-state O$(^3P_J)$ atoms with kinetic energies above the reaction barrier were produced by photolysis of N$O_2$ at 355 nm. The OH product revealed strong vibrational population inversion, P(${\nu}$"=1)/P(${\nu}$"=0) = 4.0 ${\pm}$ 0.6, and rotational distributions in both vibrational states exhibit substantial rotational excitations to the limit of total available energy. However, no preferential populations in either of the two $\Lambda$ doublet states were observed from the micropopulations, which supports a mechanism involving a direct abstraction of hydrogen by the atomic oxygen. It was also found that the collision energy between O and HSi$Cl_3$ is effectively coupled into the excitation of the internal degrees of freedom of the OH product ($$ = 0.62, and $<\;f_{rot}>$ = 0.20). The dynamics appear consistent with expectations for the kinematically constrained reaction which supports the reaction type, heavy + light-heavy $\rightarrow$ heavy-light + heavy (H + LH′ $\rightarrow$ HL + H′). The dynamics of oxygen atom collision with HSi$Cl_3$ are discussed in comparison to those with Si$H_4$.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제10권S_3호
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• pp.113-119
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• 2001

Surface sediments(0~5 cm) were sampled from 22 stations in Ulsan Bay, one of the most highly industrialized regions in Korea, in November 2000. The sediment samples were analyzed for their polycyclic aromatic hydrocarbon(PAH) content using a gas chromatography coupled to a mass spectrometer detector(GC/MSD). The total PAH concentrations in the sediments varied from 14 to 7108 ng/g dry weight with a mean value of 1052 ng/g dry weight. The level of carcinogenic PAHs ranged from 6 to 2396 ng/g dry weight with a mean value of 433 ng/g dry weight. The highest PAH concentrations in the sediments from Ulsan Bay were found at Station U8, whereas the lowest levels were observed at Stations U2 and U 17. The PAH distribution exhibited a decreasing gradient from the inner basin to the outer bay. The predominant contributors to the aromatic ring groups of the 16 PAHs were four- and five-ring groups, such as fluoranthene, pyrene, benzo[a]anthracene, chrysene, benzor[b]fluoranthene, benzor[k]fluoranthene and benzo[a]pyrene, while two- and three-ring aromatics, like naphthalene, acenapthylene, acenaphthene, fluorene, phenanthrene and anthracene, only exhibited a low concentration. The molecular indices for phenanthrene/anthracene and fluoranthen/pyrene were used to Identify the origin of the PAH contamination in the sediments. The results indicated that the PAH contamination in Ulsan Bay was mostly Pyrolytic in origin with a Petrogenic input adjacent to Ulsan and Jangsuengpo harbor.

• 한국세라믹학회지
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• 제54권6호
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• pp.506-510
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• 2017

One of the characteristics of polycrystalline graphene that determines its material properties is grain size. Mechanical properties such as Young's modulus, yield strain and tensile strength depend on the grain size and show a reverse Hall-Petch effect at small grain size limit for some properties under certain conditions. While there is agreement on the grain size effect for Young's modulus and yield strain, certain MD simulations have led to disagreement for tensile strength. Song et al. showed a decreasing behavior for tensile strength, that is, a pseudo Hall-Petch effect for the small grain size domain up to 5 nm. On the other hand, Sha et al. showed an increasing behavior, a reverse Hall-Petch effect, for grain size domain up to 10 nm. Mortazavi et al. also showed results similar to those of Sha et al. We suspect that the main difference of these two inconsistent results is due to the different modeling. The modeling of polycrystalline graphene with regular size and (hexagonal) shape shows the pseudo Hall-Petch effect, while the modeling with random size and shape shows the reverse Hall-Petch effect. Therefore, this study is conducted to confirm that different modeling is the main reason for the different behavior of tensile strength of the polycrystalline structures. We conducted MD simulations with models derived from the Voronoi tessellation for two types of grain size distributions. One type is grains of relatively similar sizes; the other is grains of random sizes. We found that the pseudo Hall-Petch effect and the reverse Hall-Petch effect of tensile strength were consistently shown for the two different models. We suspect that this result comes from the different crack paths, which are related to the grain patterns in the models.

• BMB Reports
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• 제35권2호
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• pp.186-193
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• 2002

The acid-bible subunit (ALS) associates with the insulinlike growth factor (IGF)-I or II, and the IGF binding protein-3 (IGFBP-3) in order to form a 150-kD complex in the circulation. This complex may regulate the serum IGFs by restricting them in the vascular system and promoting their endocrine actions. Little is known about how ALS binds to IGFBP3, which connects the IGFs to ALS. Xenopus oocyte was utilized to study the function of ALS in assembling IGFs into the ternary complexes. Xenopus oocyte was shown to correctly translate in vitro transcribed mRNAs of ALS and IGFBP3. IGFBP3 and ALS mRNAs were injected in a mixture, and their products were immunoprecipitated by antisera against ALS and IGFBP3. Contrary to traditional reports that ALS interacts only with IGF-bound IGFBP3, this study shows that ALS is capable of forming a binary complex with IGFBP3 in the absence of IGF When cross-linked by disuccinimidyl suberate, the band that represents the ALS-IGFBP3 complex was evident on the PAGE. IGFBP3 movement was monitored according to the distribution between the hemispheres. Following a localized translation in the vegetal hemisphere, IGFBP3 remained in the vegetal half in the presence of ALS. However, the mutant IGFBP3 freely diffused into the animal half, despite the presence of ALS, which is different from the wild type IGFBP3. This study, therefore, suggests that ALS may play an important role in sequestering IGFBP3 polypeptides via the intermolecular aggregation. Studies using this heterologous model will lead to a better understanding of the IGFBP3 and ALS that assemble into the ternary structure and circulate the IGF system.

• Journal of Ginseng Research
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• 제29권4호
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• pp.167-175
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• 2005

The $Ca^{2+}-activated$ chloride channel (CLCA) was activated by ginseng total saponin (GTS) in Xenopus oocytes. The reverse transcription PCR (RT-PCR) method was performed with gene specific primers on oocytes. The gene specific primers were deduced from spleen cDNA in expressed sequence tags (EST) database showing high homology to the mouse CLCA. Full length of cDNA sequence was completed by linkage of several 5' and 3'-half cDNA fragments have been sequenced. We named the full cDNA to oCLCA transiently. The oCLCA gene encodes a protein of 911 amino acids with $48.9\%$ identity overall to that of mouse CLCA (mCLCA4). A predicted oCLCA amino acids sequence shows the molecular weight of 108 kDa and has four or more transmembrane domains, and also the one hydrophobic C­terminal domain. oCLCA gene was expressed ubiquitously in various tissues included oocytes, also interfered in oocytes by siRNA for oCLCA. Here, we suggest that oCLCA is a endogenous chloride channel gene in oocytes. We are studying for the identification of oCLCA gene and further physiological research.

• 한국추진공학회지
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• 제20권2호
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• pp.18-23
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• 2016

유기 분자의 자기조립 다분자막은 기질의 표면에서 전자기적인 상호작용을 통해 자발적으로 형성된다. 본 연구에서는 이 기술을 응용하여 고에너지물질의 안전성과 취급용이성이 향상됨을 입증하였다. 최근 다양한 연구에서 고에너지물질 결정 내부의 결함은 물질의 안전성을 저하시키는 요인이므로, 결정 입자의 크기를 감소시키는 연구가 중요시되고 있다. 이에 따라, 결정화 방법을 통해 제조된 나노 수준의 고에너지물질을 사용하였으며, 자기조립 다분자막 기술을 응용하여 물질의 안전성을 향상시켰다. 입도/표면전하/마찰감도/정전기 전하 등을 측정하여 표면개질 여부를 확인하였다.

• Elastomers and Composites
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• 제34권2호
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• pp.147-155
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• 1999

고무와 혼합된 왁스는 고무 표면으로 이동하여 방어막을 형성한다. 일반적으로 고무의 오존화를 방지하기 위해 오존노화방지제를 왁스와 함께 사용하고 있다. 다양한 종류의 왁스가 첨가된 천연고무 가류물을 이용하여 왁스막이 오존노화방지제의 이동에 미치는 영향을 연구하였다 오존노화방지제로 IPPD (N-isopropyl-N'-phenyl-p-phenylenediamine), HPPD (N-l,3-dimethylbutyl-N'-phenyl-p-phenylenediamine), SBPPD (N,N'-di(sec-butyl)-p-phenylenediamine), 그리고 DMPPD (N,N'-di(1,4-dimethylpentyl)-p-phenylenediamine)를 사용하였다. 노화방지제 이동 실험은 $60^{\circ}C$ 와 $80^{\circ}C$에서 10, 20, 30일간 실시하였다. 노화방지제의 이동속도는 고무가류물에 왁스가 없을 때가 있을 때보다 빨랐으며 분자량이 큰 왁스가 혼합되었을 때가 분자량이 작은 왁스가 혼합되었을 때보다 느렸다. DMPPD와 SBPPD의 이동속도가 HPPD와 IPPD의 이동속도보다 빨랐다.

• 한국자원식물학회지
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• 제30권3호
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• pp.323-330
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• 2017

Eleutherococcus senticosus (Siberian ginseng) is an important medicinal tree found in northeast Asia. In this study, we analyzed the genome-wide distribution of microsatellites in E. senticosus. By sequencing 711 clones from an SSR-enriched genomic DNA library, we obtained 12 polymorphic SSR markers, which also revealed successful amplicons in E. senticosus accessions. Using the developed SSR markers, we estimated genetic diversity and population structure among 131 E. senticosus accessions in Korea and China. The number of alleles ranged from 2 to 11, with an average of 7.4 alleles. The mean values of observed heterozygosity ($H_O$) and expected heterozygosity ($H_E$) were 0.59 and 0.56, respectively. The average polymorphism information content (PIC) was 0.51 in all 131 E. senticosus accessions. E. senticosus accessions in Korea and China showed a close genetic similarity. Significantly low pairwise genetic divergence was observed between the two regions, suggesting a relatively narrow level of genetic basis among E. senticosus accessions. Our results not only provide molecular tools for genetic studies in E. senticosus but are also helpful for conservation and E. senticosus breeding programs.

• 대한화학회지
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• 제55권4호
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• pp.691-696
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• 2011

CTAB 혹은 CTAB-나피온 촉매를 속빈 실리콘 튜브형 MCM-41에 담지시켰다. 이들 촉매들을 XRD, SEM, BET 등으로 분석하였다. 이들을 1,7-heptanediol 의 브롬화 반응 촉매로 사용하였고 다른 촉매들과 비교하였다. 이들 촉매들은 CTAB 보다 효과가 좋았으며 CTAB-Nafion/MCM-41 이 성능이 가장 우수하였다.

• 대한화학회지
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• 제55권4호
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• pp.673-679
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• 2011

지글러-나타 촉매를 사용하여 에틸렌을 중합함으로써 다양한 공단량체의 종류와 조성을 갖는 이중 분자량 분포의 고밀도 폴리에틸렌이 합성되었다. 이들의 구조와 물성을 GPC, NMR, DSC, 인장 측정기를 이용하여 연구하였다. 에틸렌/1-헥센 공중합체가 에틸렌/1-부텐 공중합체보다 비슷한 조성을 가질 경우 높은 인장강도와 파단연신율을 가짐을 확인 하였다. 분자량은 고분자의 공단량체 비율이 증가할수록 감소하였다. 짧은 곁사슬은 결정화도에 영향을 주어 결과적으로 이중 분자량 분포를 갖는 고밀도 폴리에틸렌의 모폴로지와 기계적 물성에 영향을 미쳤다. SSA로 처리 후 다수의 발열 곡선이 관찰되었으며 이는 주로 에틸렌 배열길이와 라멜라 두께의 불균일성에 기인한다. 분포지수의 차이로부터 공단량체의 조성이 높은 폴리에틸렌의 SCB 분포가 균일도를 향상시킴을 알 수 있었다.