• 공업화학
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• 제20권6호
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• pp.685-691
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• 2009

하이드록시기 유무, 극성도, 분자 크기가 서로 다른 용매 6종의 단일 용매 또는 혼합 용매계 흄드 실리카 분산체를 제조하고 각 분산체의 점도 및 유변학적 거동을 용매계의 특성의 관점에서 고찰하였다. 하이드록시기 포함 용매에 실리카를 분산하였을 때 안정적이고 저점도의 sol을 형성하였고 하이드록시기가 없고 비극성인 용매는 고점도의 gel을 형성하였다. 비극성 용매계 실리카 분산체에 하이드록시기 함유 용매를 첨가하면 일정 함량까지는 점도 감소 현상을 관찰할 수 있었으며, 더 이상의 점도 변화가 발생하지 않는 최소 임계함량이 있었다. 최소 임계함량은 하이드록시기 미포함 용매의 극성도가 클수록 줄어들었다. 하이드록시기 포함 용매계 실리카 분산체가 안정적인 저점도의 sol을 형성하는데 이는 실리카 표면의 실란올기와 용매의 하이드록시기간의 수소결합을 통한 용매화로 저점도 sol을 형성하는 것으로 볼 수 있다. 비극성용매에 실리카를 분산하였을 때는 실리카 표면의 실란올기 사이의 수소 결합을 통해 응집이 일어나 고점도의 gel이 형성되었다.

• 접착 및 계면
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• 제15권4호
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• pp.161-168
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• 2014

페놀과 피리딘 간의 단일 수소결합을 이용하여 새로운 형태의 자기 집합된 원반형 액정을 제조하고 그 액정 특성을 조사하였다. 원반형 구조 설계를 위해 phloroglucinol을 중심부 분자로, 체계적으로 알킬사슬 길이를 변화시킨 trans-4-alkoxy-4'-stilbazole을 주변 물질로 사용하였다. 적외선 분광 분석을 통해 중심부 분자와 주변 물질 사이의 분자간 수소결합이 성공적으로 형성됨을 확인하였고, 또한 수소결합의 안정성이 분자 정렬에 의해 크게 영향을 받음을 확인하였다. 자기 집합된 원반형 액정 복합체는 원반형 메소겐 주위의 알킬 사슬 길이에 따라 다른 액정상들을 나타내었다. 긴 알킬사슬을 함유하는 액정 복합체의 경우 육방형 컬럼상이 나타났으며, 상대적으로 짧은 사슬을 갖는 다른 액정 복합체에서는 네마틱 컬럼상이 형성되었다. 이는 자기 집합된 원반형 액정 복합체의 액정상 구조가 원반형 핵 단위 주변의 알킬사슬 길이에 의해 크게 영향을 받음을 의미하였다.

• 대한화학회지
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• 제53권3호
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• pp.266-271
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• 2009

고체 화합물 La7Os4C9 속에 있는 [Os4C9]21‑ 사슬의 전자구조와 화학결합을 extended Hückel 계산 결과에 의해서 논의하였다. 탄소 원자는 물론 (C2)2‑ 분자의 결합 특성은 비교적 큰 Os-C 상호작용을 나 타내었고 특히 (C2)2‑ 분자의 결합길이 증가는 Fermi level 바로 아래에 Os-C2(1 πg) 결합 밴드의 존재로 인 해서 반결합 1πg 오비탈에 부분적인 전자점유가 일어나기 때문인 것으로 해석된다.

• Bulletin of the Korean Chemical Society
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• 제35권9호
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• pp.2787-2790
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• 2014

Quercetin is a major dietary flavonoid found in onions, apples, tea, and red wine, and potentially has beneficial effects on disease prevention. We carried out this study to investigate the effect of quercetin on UVB-induced matrix metalloproteinase-1 (MMP-1) expression in human keratinocyte HaCaT cells and to further understand the mechanisms of its action. The anti-inflammatory activity of quercetin was investigated and quercetin significantly suppressed the NO production in LPS-stimulated RAW264.7 mouse macrophages. Post treatment of quercetin decreased UV irradiation-induced phosphorylation of JNK, p38 MAPK, and ERK by 91%, 21%, and 17%, respectively. MMP-1 is mainly responsible for the degradation of dermal collagen during the aging process of human skin and quercetin suppressed the UVB-induced MMP-1 by 94%. Binding studies revealed that quercetin binds to p38 with high binding affinity ($1.85{\times}10^6M^{-1}$). The binding model showed that the 4'-hydroxy groups of the B-ring of quercetin participated in hydrogen bonding interactions with the side chains of Lys53, Glu71, and Asp168 and the 5-hydroxy group of the A-ring formed a hydrogen bond with the backbone amide of Met109. The major finding of this study shows that quercetin inhibits phosphorylation of JNK, p38 MAPK, and ERK pathway leading to the prevention of MMP-1 expression in human keratinocyte HaCaT cells. Therefore, our findings suggested the potentials of quercetin as a skin anti-photoaging agent.

• Macromolecular Research
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• 제14권2호
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• pp.173-178
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• 2006

Poly(3-(2-hydroxyethyl)thiophene) (P3HET) was synthesized using oxidative coupling polymerization that involved the protecting and deprotecting of hydroxyl groups but not the chlorine substitution or oxidative decomposition of the hydroxyl groups. The resulting P3HET exhibited good solubility in aprotic solvents, in contrast to the insoluble polymer product synthesized directly from the monomer, 3-(2-hydroxyethyl)thiophene (3HET). P3HET had low conductivity due to the strong hydrogen bonding of its hydroxyl groups. The ester-functionalized poly(3-(2-acetoxyethyl)thiophene) and poly(3-(4-pentylbenzoateethyl)thiophene) were also prepared with reasonably high molecular weights in order to examine how this functionalization modified the physical and chemical properties of P3HET. These polymers exhibited better solubility in common solvents and higher conductivity than P3HET. All these polymers exhibited bathochromic shifts of their film state absorption maxima with respect to those found in the UV-visible spectra of their solution phases. The extent of the bathochromic shift was found to vary with the lengths of the side chains of the ester-functionalized polymers.

• Bulletin of the Korean Chemical Society
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• 제32권8호
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• pp.2695-2699
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• 2011

${\beta}$ Ketoacyl acyl carrier protein synthase III (KAS III) initiates fatty acid synthesis in bacteria and is a key target enzyme to overcome the antibiotic resistance problem. In our previous study, we found flavonoid inhibitors of Enterococcus faecalis KAS III and proposed three potent antimicrobial flavonoids against Enterococcus faecalis and Vancomycin-resistant Enterococcus faecalis with MIC values in the range of 128-512 ${\mu}g/mL$ as well as high binding affinities on the order from $10^6$ to $10^7\;M^{-1}$. Using these series of flavonoids, we conducted biological assays as well as docking study to find potent flavonoids inhibitors of Staphylococcus aureus KAS III with specificities against Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus. Here, we propose that naringenin (5,7,4'-trihydroxyflavanone) and eriodictyol (5,7,3',4'-tetrahydroxyflavanone) are potent antimicrobial inhibitors of Staphylococcus aureus KAS III with binding affinity of $3.35{\times}10^5$ and $2.01{\times}10^5\;M^{-1}$, respectively. Since Arg38 in efKAS III is replaced with Met36 in saKAS III, this key difference caused one hydrogen bond missing in saKAS III compared with efKAS III, resulting in slight discrepancy in their binding interactions as well as decrease in binding affinities. 4'-OH and 7-OH of these flavonoids participated in hydrogen bonding interactions with backbone carbonyl of Phe298 and Ser152, respectively. In particular, these flavonoids display potent antimicrobial activities against various MRSA strains in the range of 64 to 128 ${\mu}M$ with good binding affinities.

• Journal of Ginseng Research
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• 제47권2호
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• pp.228-236
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• 2023

Background: QiShen YiQi pills (QSYQ) is a Traditional Chinese Medicine (TCM) formula, which has a significant effect on the treatment of patients with myocardial infarction (MI) in clinical practice. However, the molecular mechanism of QSYQ regulation pyroptosis after MI is still not fully known. Hence, this study was designed to reveal the mechanism of the active ingredient in QSYQ. Methods: Integrated approach of network pharmacology and molecular docking, were conducted to screen active components and corresponding common target genes of QSYQ in intervening pyroptosis after MI. Subsequently, STRING and Cytoscape were applied to construct a PPI network, and obtain candidate active compounds. Molecular docking was performed to verify the binding ability of candidate components to pyroptosis proteins and oxygen-glucose deprivation (OGD) induced cardiomyocytes injuries were applied to explore the protective effect and mechanism of the candidate drug. Results: Two drug-likeness compounds were preliminarily selected, and the binding capacity between Ginsenoside Rh2 (Rh2) and key target High Mobility Group Box 1 (HMGB1)was validated in the form of hydrogen bonding. 2 μM Rh2 prevented OGD-induced H9c2 death and reduced IL-18 and IL-1β levels, possibly by decreasing the activation of the NLRP3 inflammasome, inhibiting the expression of p12-caspase1, and attenuating the level of pyroptosis executive protein GSDMD-N. Conclusions: We propose that Rh2 of QSYQ can protect myocardial cells partially by ameliorating pyroptosis, which seems to have a new insight regarding the therapeutic potential for MI.

• 폴리머
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• 제24권4호
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• pp.488-498
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• 2000

주쇄로 poly(4-vinylpyridine) (P4VP)과 양친매성 측쇄로 3-pentadecylphenol (PDP)의 수소결합을 통해서 molecular bottle-brush를 제조하였다. 제조된 bottle-brush에 대하여 P4VP의 pyridine기 대 PDP의 몰비 (x)와 P4VP 분자량에 따른 액정성의 구조, 상전이온도( $T_{ODT}$)와 bottle-brush 층간거리 ( $L_{p}$)변화에 대하여 고찰하였다. P4VP-PD $P_{x}$ bottle-brush는 상온영역에서 미세상분리를 이루고 있는 라멜라구조로 조사되었다. Bottle-brush의 온도에 따른 상거동에 대한 조사에서 상한임계온도(UCST)거동을 나타내었다. 또한 P4VP의 분자량별로 x가 0.8-0.9일때 최대온도를 나타내었으며, P4VP의 분자량이 증가함에 따라서 상전이가 높은 온도에서 일어났다. 이러한 결과는 주쇄긴 P4VP의 유동성과 라멜라구조의 크기와 규칙성에 영향을 받음을 알 수 있었다. Bottle-brush의 라멜라구조 분석시 bottle-brush의 $L_{p}$는 35 $\AA$에서 40 $\AA$로 x보다는 P4VP의 분자량에 더 큰 영향을 받았다. P4VP의 분자량이 증가함에 따라서 $L_{p}$도 증가하였으나, 일정 크기이상으로 분자량이 커졌을 경우, 오히려 거리가 감소하거나 증가하지 않는 결과를 얻었다.결과를 얻었다.다.

• Journal of the Korean Wood Science and Technology
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• 제17권2호
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• pp.20-25
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• 1989

This study was carried out in order to investigate the treatment effect of PEG soln which is a common dimensional stabilizer to green log. sawing panel etc, on bonding product including plywood widely-used in secondary processing unit. The 30% concentration of aqueous PEG soln. with molecular weight of 400, 1.000 and 4,000 were prepared respectively, and also dipping the veneer in the PEG soln. spreading the PEG soln. on veneer and mixing the PEG soln. in the adhesive were allowed. Then the ratio of PEG impregnation on veneer, the adhesive strength of plywood were epitomized as follows: The ratio of impregnation by PEG 4,000 at dipping condition was highest. while that by PEG 400 at same condition was lowest. However, the effect of PEG molecular weight on the ratio of impregnation at spreading condition did not occur. 2. The adhesive strength was great in the order of 4,000>400>1,000 in molecular weight of PEG at dipping and spreading conditions. In case of mixing the PEG soln. in the adhesive, the adhesive strength was great in the order of 400>1,000>4,000 in molecular weight of PEG. Throughout three treatment conditions, PEG 400 was relatively favourable with about 10kg/$cm^2$ dry strength. 3. The adhesive strength was great 10 the order of spreading >dipping >mixing condition. 4. Although adhesive strength with the 30% concentration of aqueous PEG soln. was decreased by 35% and over, compared to control (non-treatment) adhesive strength, all types of PEG treatment except mixing the PEG soln. in the adhesive exceeded the standard dry strength for common use panel. 7.5kg/$cm^2$. 5. In warm water-proof test, the adhesive strengths by all PEG treatment conditions were less than the standard wet strength, 7.5kg cot, and also delamination of glue line occured mostly in mixing in the PEG soln. in the adhesive condition.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.186-186
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• 2013

Nitrogen doped Ge-Sb-Te (N-GST) thin films for phase change random access memory (PRAM) applications were investigated by synchrotron-radiation-based x-ray photoelectron spectroscopy and absorption spectroscopy. Nitrogen doping in GST resulted in more favorable N atoms' bonding with Ge atoms rather than with Sb and Te atoms [1,2], which explains the higher phase change transition temperature than that of undoped Ge-Sb-Te thin film. Surprisingly, it was noticed that N atoms also existed in the form of molecular nitrogen, $N_2$, which is detrimental to the stability of the GST performance [3]. N-doped GST experimental features were also supported by ab-initio molecular dynamic calculations [2]. References [1] M.-C. Jung, Y. M. Lee, H.-D. Kim, M. G. Kim, and H. J. Shin, K. H. Kim, S. A. Song, H. S. Jeong, C. H. Ko, and M. Han, "Ge nitride formation in N-doped amorphous Ge2Sb2Te5", Appl. Phys. Lett. 91, 083514 (2007). [2] Zhimei Sun, Jian Zhou, Hyun-Joon Shin, Andreas Blomqvist, and Rajeev Ahuja, "Stable nitride complex and molecular nitrogen in N doped amorphous Ge2Sb2Te5", Appl. Phys. Lett. 93, 241908 (2008). [3] Kihong Kim, Ju-Chul Park, Jae-Gwan Chung, and Se Ahn Song, Min-Cherl Jung, Young Mi Lee, Hyun-Joon Shin, Bongjin Kuh, Yongho Ha, Jin-Seo Noh, "Observation of molecular nitrogen in N-doped Ge2Sb2Te5", Appl. Phys. Lett. 89, 243520 (2006).