• Bulletin of the Korean Chemical Society
• /
• 제31권2호
• /
• pp.453-456
• /
• 2010

The structural and energetic preferences of thiacalix[4]biscrown-5 with and without alkali metal ions ($Na^+$, $K^+$, $Rb^+$, and $Cs^+$) have been theoretically investigated for the first time using molecular dynamic (MD) simulations and density functional theory (MPWB1K/6-31G(d)//B3LYP/6-31G(d)) methods. The formation of the metal ion complex by the host is mainly driven by the electrostatic attraction between crown-5 oxygens and a cation together with the minor contribution of the cation-$\pi$ interaction between two facing phenyl rings around the cation. The computed binding energies and the atomic charge distribution analysis for the metal binding complexes indicate the selectivity toward a potassium ion. The theoretical results herein explain the experimentally observed extractability order by this host towards various alkali metal ions. The physical nature and the driving forces for cation recognition by this host are discussed in detail.

• The Korean Journal of Physiology and Pharmacology
• /
• 제24권1호
• /
• pp.121-126
• /
• 2020

The ezrin-radixin-moesin (ERM) proteins are a family of membrane-associated proteins known to play roles in cell-shape determination as well as in signaling pathways. We have previously shown that amphetamine decreases phosphorylation levels of these proteins in the nucleus accumbens (NAcc), an important neuronal substrate mediating rewarding effects of drugs of abuse. In the present study, we further examined what molecular pathways may be involved in this process. By direct microinjection of LY294002, a PI3 kinase inhibitor, or of S9 peptide, a proposed GSK3β activator, into the NAcc core, we found that phosphorylation levels of ERM as well as of GSK3β in this site are simultaneously decreased. These results indicate that ERM proteins are under the regulation of Akt-GSK3β signaling pathway in the NAcc core. The present findings have a significant implication to a novel signal pathway possibly leading to structural plasticity in relation with drug addiction.

• 한국식품영양과학회지
• /
• 제23권3호
• /
• pp.466-471
• /
• 1994

The antioxidant activity of methanol extracts of thirty plants was tested using the methol of 1, 1-diphenyl-2-pi-cryl hydrazyl (DPPH) reactivity. Four methanol extracts from Zingiber officinale, Piper nigrum , Zanthoxylum schinifolium and Capsocum annuum were found to be the most effective on DPPH radical scavenging activity. The next effective ones were Perilla frutescens , Sedium sarmentosum , Raphnus sativas, aArctium lappa, Beta vulgaris. Brassica oleracea var. Acephala, bBrassica juncea inorder, and the others did not show a considerable activity. The methanol extract obtained from the seed coats of Zanthoxylum schinifolium was fractinated with several sovlents. The interphase materials exhibited the strongest antioxidant activity and was further purified by silica gel and Sephadex LH-20 column chormatography. Two active principles were isolated and identified as quercetin -3-O-$\alpha$-L-rhamonopyranoiside(quercitrin) and quercetin 3-O-$\alpha$-D-galactopyranoside (hyperoside) by ultraviolet(UV), proton nuclear magetic resonance (1H-NMR) and carbon nuclear magnetic resonance (13C-NMR). Its antioxidative activity was a little higher that that of L-ascorbic acid.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1995년도 춘계학술대회 논문집
• /
• pp.220-223
• /
• 1995

Stable polyion-complexed polymeric monolayrers were prepared by spreading perfluoroalkyl monomaleatd copolymers. C$_2$F$\_$8/MA-VE$_2$ and C$_2$F$\_$8/Mv-VE$_3$ on aqueous poly(allylamine) subphase. The monolayer properties have been studied by the surface pressure-area($\pi$-A) isotherms. The C$_2$F$\_$8/MA-VE$_3$containing longer oligoethyleneglycol pendant showed more expaned monolayer phase than the C$_2$F$\_$8/MA-VE$_2$ The polyion-complexed monolayers were transferable on various substrates, and the resulting Langmuir-Blodgett(LB) films were characterized b ET-IR spectroscopy and scanning electron microscopy(SEM) Two-dimensional crosslinking to from a polymer network was achieved by amide formation through heat treatment under vacuum with concurrent removel of perfluoroalkyl tails. SEM observation of this film ona porous membrane filter showed that the four layer film was sufficiently stable to cover the filter pore size of 0.1$\mu\textrm{m}$. The C$_2$F$\_$8/MA-VE$_3$revealed better covering capability than the C$_2$F$\_$8/MA-VE$_2$Immersion of this film in water or in benzend did not cause any change in its appearance and in FT-IR spectra.

• 정보처리학회논문지C
• /
• 제8C권1호
• /
• pp.68-74
• /
• 2001

본 논문에서는 네트워크 관리 시스템에서 SNMP(Simple Network Management Protocol) 프로토콜을 이용한 중앙 집중형 방식과 이동 에이젠트(mobile agent)를 이용한 분산방식 각각의 성능을 평가하기 위한 성능평가 모델을 제시한다. 먼저 균등 네트워크 상에서 적용 가능한 모델을 제시하고 실제 실험을 통하여 각 파라미터 값의 변화에 따른 네트워크 수행 시간을 비교한다. 다음으로 비균등 네트워크에 적용 가능하도록 모델을 확장하고, 제시한 모델을 응용하여 실제 가상의 시나리오 하에서 네트워크 소요시간을 줄일 수 있는 방안과 그에 대한 실험 결과를 제시한다. 본 성능평가 모델은 차후 네트워크 관리시스템을 개발할 때에, 효율적인 패러타임(paradigm)과 수행 구조를 선택하는데 도움이 될 수 있을 것이다.

• 미생물학회지
• /
• 제30권3호
• /
• pp.187-192
• /
• 1992

서해 경기만의 6개 정점을 대상으로 1990년 3월부터 1991년 10월까지 총 8외에 걸처 석유 분해세균의 공간적, 시간적 분포를 조사하였다. 또한, 서로 다른 배양 조건하에서의 해양 세균 군집의 석유 뷴해능도 연구하였다. 연구 기간 중, 종속 영양세균수와 석유분해세균수는 각각 7,000-108,000 CFU/ml, 0-2, 800 MPN/100 ml 로 측정되었다. 석유분해세균의 공간적 분포는 석유 탄화수소의 존제에 의하여 심하게 영향을 받은 것으로 나타났다. 실혐실내 실험에서, 석유 분해는 배양액에 yeast extract, cell free extract 의 첨가 그리고 석유뷴해세균의 접종에 의하여 증진되었다.

• 한국막학회:학술대회논문집
• /
• 한국막학회 1997년도 추계 총회 및 학술발표회
• /
• pp.39-45
• /
• 1997

Introduction : Polyimides are one of the most important classes of the high performance polymers due to their excellent electrical, thermal, and high-temperature mechanical properties. But their uses are limited because of their poor solubility. Most polyimide derivatives are processed in the form of polyamic acids, which are subsequently converted into the imide structures.Recently, it has been found that the soluble polyimides with large molecular weight sufficient to application. For enhancing processability, the majority of approaches have involved the following factors. As much as, the separation of the imide ring along the back-bone, that is to say, reducing the density of imide ring in the repeat structure. The introduction of bulky substituents along the back-bone, in order to enhance the free volume of main-chain. The incorporation of flexible or thermally stable linkages in the main-chain, reducing the packing force. The disruption of symmetry or recurrence regularity through copolymerization in order to reduce crystallnity.The objectives of this investigation are the synthesis and characterization of soluble polyimides as membrane materials by the single-step polymerization and the preparation of the asymmetric polyimide membrane by using phase inversion technique. In the present study, three series of polyimide derivatives are synthesized; H series is homopolyimides, A series is prepared from single dianhydride and two diamines, B series is yielded from two dianhydrides and a diamine. The dope solution was directly prepared from the PI solution via one step polymerization from monomers.

• Asian Pacific Journal of Cancer Prevention
• /
• 제17권8호
• /
• pp.3865-3869
• /
• 2016

Curcumin, a polyphenolic compound isolated from the rhizomes of an herbaceous perennial plant, Curcuma longa, is known to possess anticancerous activity. However, the mechanism of apoptosis induction in cancers differs. In this study, we have (1) investigated the anticancerous activity of curcumin on REH and RS4;11 leukemia cells and (2) studied the chemo-sensitizing potential of curcumin for doxorubicin, a drug presently used for leukemia treatment. It was found that curcumin induced a dose dependent decrease in cell viability because of apoptosis induction as visualized by annexin V-FITC/ PI staining. Curcumin-induced apoptosis of leukemia cells was mediated by PARP-1 cleavage. An increased level of caspase-3, apoptosis inducing factor (AIF), cleaved PARP-1 and decreased level of Bcl2 was observed in leukemia cells after 24h of curcumin treatment. In addition, curcumin at doses lower than the $IC_{50}$ value significantly enhanced doxorubicin induced cell death. Therefore, we conclude that curcumin induces apoptosis in leukemia cells via PARP-1 mediated caspase-3 dependent pathway and further may act as a potential chemo-sensitizing agent for doxorubicin. Our study highlights the chemo-preventive and chemo-sensitizing role of curcumin.

• 한국결정학회지
• /
• 제2권2호
• /
• pp.28-31
• /
• 1991

4-크로로-4'-메톡시-2-니트로디페닐아민, (C12H11N2O3CL, FW=278.70)의 단것세포 상수는 a=8,169(3), b=8.883(1), c=9.150(1) h, α =82. 98(1), β=104.80(2), y=101.43(2)", V=627.3 A3, F(000)=288.0, Dc=1.48g/cm3, u=3.06cm-1, 7=295" K, 공간군 Pi, 번호 2, 삼사 정계 이며, Z=2이다. λ (Mo-Ka)=0.7107A을 사용 하여 수집한 독립적인 회절 반점 1541개로 구조분 석한 최종 신뢰도 값은 각각 R=0.032, Rw=0.033 이며, S=0.46이다. 본 화합물은 암모니아의 두개 의 수소 대신에 4-크로로-페닐기와 4-메톡시-페닐기로 치환된 물질로써, 질소와 두 페닐기 사이의 각과 결합거리 들은 각각 125.42", 1.362 및 1.428 A 인바 수소와 함께 SP2_혼성결합을 하고있다. 질소를 포함한 두 면간 각은 63.29"이다. 분자간 어 떠 한 수소결합을 하고 지지 않다.

• BMB Reports
• /
• 제47권10호
• /
• pp.581-586
• /
• 2014

Epidermal growth factor (EGF) is known to play key roles in skin regeneration and wound-healing. Here, we demonstrate that Pep2-YAC, a tripeptide covering residues 29-31 in the B loop of EGF, promotes the proliferation of HaCaT keratinocytes with activity comparable to EGF. The treatment of HaCaT cells with Pep2-YAC induced phosphorylation, internalization, and degradation of EGFR and organization of signaling complexes, which consist of Grb2, Gab1, SHP2, and PI3K. In addition, it stimulated the phosphorylation of ERK1/2 at Thr 202/Tyr 204 and of Akt1 at Ser 473 and the nuclear translocation of EGFR, STAT3, c-Jun, and c-Fos. These results suggest that Pep2-YAC may be useful as a therapeutic agent for skin regeneration and wound-healing as an EGFR agonist.