유리系 內의 Ferrite의 Mossbauer Spectra

安振盛,金俊植,李敬行,趙壽烈,董徹,洪致裕 동국대학교 자연과학연구소 1984 자연과학연구 논문집 Vol.4 No.-

本 硏究는 5NiO-5CdO-10Fe₂O₃-30Na₂CO₃-10SiO₂(mole %)유리계에 대한 Mossbauer parameter의 溫度依存性을 조사하였다. Mossbauer spectrum은 한쌍의 Quadrupole doublet의 중첩으로 fitting하였으며 이중 하나는 tetrahedral site,다른 하나는 octahedral site이다. 상대적인 共鳴吸收面積比로부터 octahedral site와 tetrahedral site에 대한 Debye temperature를 계산하여 본 결과 각각 418K, 449K 임을 알았다. 또한 θ?값들을 이용해 least square method로 isomer shiftdral site의 壓力依存系數 α와 2.97×10?mm/sec K, I.S(0)일때의 를 평가해본 결과 octahedral site의 α는 2.97×10?mm/sec K,I.S(0)는 tetrahedral site이고 α의 3.2305×10?mm/sec K, I.S(0)는 0.276mm/sec임을 알았다. 그리고 quadrupole splitting은 측정온도가 증가함에 따라 서서히 감소함을 알았다. The temperature dependence of the Mossbauer parameter for 5NiO-5CdO-10Fe₂O₃-30Na₂CO₃-10SiO₂(mole %) quenched glass system was investigated. The spectra were fitted as superposition of a pair of quadrupole double ; One is for the tetrahedral site and the other is for the octahedral site. From the relative absorption area ratios of the spectra, the Debye erature of two sites were calculated to be 418K and 449K for the octahedral site and the ?edrai site, respectively. From these Debye temperatures, We can see that the isomer shifts and the coefficients αof the pressure dependence of the isomer shift are 0.456mm/sec, 2.97×10?mm/sec K for octahedral site and 0.276mm/sec K, 3.2305×10?mm/sec K for ?edral site. Also, we can see that the quadrupole splittings of two sites are gradually decresed the increase of the measuring temperature.

DMNQ S-64 Induces Apoptosis via Caspase Activation and Cyclooxygenase-2 Inhibition in Human Nonsmall Lung Cancer Cells

LIM, E.-S.,RHEE, Y.-H.,PARK, M.-K.,SHIM, B.-S.,AHN, K.-S.,KANG, H.,YOO, H.-S.,KIM, S.-H. Wiley (Blackwell Publishing) 2007 Annals of the New York Academy of Sciences Vol.1095 No.1

<P>Shikonin has been reported to induce apoptosis and inhibit angiogenesis in vivo and in vitro. 6-(1-propoxyiminoalkyl)-5,8-dimethoxyoxy 1,4-naphtoquinone S-64 (DMNQ S-64) was synthesized as a shikonin derivative. In this article, the underlying apoptotic mechanism of DMNQ S-64 was examined. DMNQ S-64 exerted cytotoxicity against A549 lung carcinoma cells with IC(50) of 27.3 microM. Apoptotic bodies were observed in DMNQ S-64-treated A549 cells by 4'-6-diamidino-2-phenylindole (DAPI) staining assay. DMNQ S-64 also increased sub-G1 DNA portion in a concentration-dependent manner by flow cytometric analysis. Western blotting has revealed that DMNQ S-64 effectively activates the expression of caspase 8, 9, and 3, cleaves poly (ADP-ribose) polymerase, and increases the ratio of Bax/Bcl-2. Furthermore, cytochrome c was released in a concentration-dependent manner by DMNQ S-64. Similarly, DMNQ S-64 significantly increased caspase 3 activity by enzyme-linked immunosorbent assay (ELISA). It also significantly inhibited the level of prostaglandin E2 (PGE(2)) by ELISA and downregulated the expression of cyclooxygenase-2 (COX-2) in a concentration-dependent manner. Taken together, DMNQ S-64 may exhibit cytotoxicity against A549 cells via caspase activation and COX-2 inhibition.</P>

Comparison of contractile mechanisms of sphingosylphosphorylcholine and sphingosine-1-phosphate in rabbit coronary artery

Choi, S.-K.,Ahn, D.-S.,Lee, Y.-H. Oxford University Press 2009 Cardiovascular research Vol.82 No.2

<P>AIMS: Although stimulation with sphingosylphosphorylcholine (SPC) or sphingosine-1-phosphate (S1P) generally leads to similar vascular responses, the contractile patterns and their underlying signalling mechanisms are often distinct. We investigated the different reliance upon Ca2+-dependent and Ca2+-sensitizing mechanisms of constriction in response to SPC or S1P in coronary arteries. METHODS AND RESULTS: Contractile responses, changes in [Ca2+]i, and phosphorylation of myosin light chain phosphatase-targeting subunit (MYPT1) were measured. SPC induced a concentration-dependent sustained contraction. S1P evoked a rapid rise in force (initial transient), which was followed by a secondary sustained force. In the absence of extracellular Ca2+, the concentration dependency of constriction to SPC was shifted to the right, but with no change in maximum force, whereas S1P-induced contraction was significantly blunted. Cyclopiazonic acid (CPA) significantly decreased the initial transient force induced by S1P. In isolated single cells, S1P markedly increased [Ca2+]i, whereas only a modest elevation was noted with SPC. The S1P-induced elevation of [Ca2+]i was abolished by pre-treatment with CPA and was significantly reduced in the absence of extracellular Ca2+. In beta-escin-permeabilized strips, SPC augmented pCa 6.3-induced force; this was significantly inhibited by fasudil hydrochloride. S1P induced little or no augmentation of pCa 6.3-induced force. In intact arteries, SPC-induced contraction was completely inhibited by fasudil hydrochloride. Fasudil hydrochloride had no effect on the initial transient force induced by S1P but significantly inhibited the secondary sustained force. SPC induced a several-fold increase in Thr696 and Thr853 phosphorylation of MYPT1, but S1P did not affect phosphorylation of MYPT1. CONCLUSION: Our results suggest that constriction of coronary arteries in response to the bioactive lipid S1P or SPC occurs by distinct signalling pathways. Activation of the RhoA/RhoA-associated kinase pathway and subsequent phosphorylation of MYPT1 play a key role in SPC-induced coronary contraction, whereas elevation of [Ca2+]i is crucial for S1P-induced coronary constriction.</P>

Formaldehyde 처리 귀리의 젖소 소화관내 영양소 분해율 측정

이상철(S . C . Lee),김병기(B . K . Kim),문여황(Y . H . Moon),문점동(C . D . Moon),안병홍(B . H . Ahn) 한국영양사료학회 1996 韓國營養飼料學會誌 Vol.20 No.1

Interference Effect betweenϕandΛ(1520)Production Channels in theγp→K+K−pReaction near Threshold

Ryu, S. Y.,Ahn, J. K.,Nakano, T.,Ahn, D. S.,Ajimura, S.,Akimune, H.,Asano, Y.,Chang, W. C.,Chen, J. Y.,Daté,, S.,Ejiri, H.,Fujimura, H.,Fujiwara, M.,Fukui, S.,Hasegawa, S.,Hicks, K.,Horie, K.,Ho American Physical Society 2016 Physical Review Letters Vol.116 No.23

<P>The phi-Lambda(1520) interference effect in the gamma p -> K(+)K(-)p reaction has been measured for the first time in the energy range from 1.673 to 2.173 GeV. The relative phases between phi and Lambda(1520) production amplitudes were obtained in the kinematic region where the two resonances overlap. The measurement results support strong constructive interference when K+K- pairs are observed at forward angles but destructive interference for proton emission at forward angles. Furthermore, the observed interference effect does not account for the root s = 2.1 GeV bump structure in forward differential cross sections for phi photoproduction. This fact suggests possible exotic structures such as a hidden-strangeness pentaquark state, a new Pomeron exchange, or rescattering processes via other hyperon states.</P>

Covering a simple polygon by monotone directions

Ahn, H.K.,Brass, P.,Knauer, C.,Na, H.S.,Shin, C.S. Elsevier 2010 Computational Geometry Vol.43 No.5

In this paper we study the problem of finding a set of k directions for a given simple polygon P, such that for each point p@?P there is at least one direction in which the line through p intersects the polygon only once. For k=1, this is the classical problem of finding directions in which the polygon is monotone, and all such directions can be found in linear time for a simple n-gon. For k>1, this problem becomes much harder; we give an O(n<SUP>5</SUP>log<SUP>2</SUP>n)-time algorithm for k=2, and O(n<SUP>3k+1</SUP>logn)-time algorithm for fixed k>=3.

Electrochemical analysis on the growth of oxide formed on stainless steels in molten carbonate at 650 ^oC

Ahn, S.,Oh, K.,Kim, M.,Youn, J.,Jo, K.,Kim, K.,Kwon, H. Pergamon Press ; Elsevier Science Ltd 2014 International journal of hydrogen energy Vol.39 No.23

The oxide growth on stainless steel (SS) 310S and 316L, used as a cathode current collector material of molten carbonate fuel cell (MCFC), were examined in the mixture of 62 mol% Li<SUB>2</SUB>CO<SUB>3</SUB>-38 mol% K<SUB>2</SUB>CO<SUB>3</SUB> at 650 <SUP>o</SUP>C by measuring the change in corrosion potential and potentiodynamic response of the alloys and also in terms of impedance analysis on the alloy|oxide layer|electrolyte system. The corrosion potential of SS 316L was in an active region for 12 h-immersion, whereas that of SS 310S drastically increased after 6 h-immersion due to an active to passive transition. The corrosion rate of the two SSs decreased with immersion due to the growth of protective oxide. However, the decrease in the corrosion rate of SS 310S is much greater than that of SS 316L. The oxide formed on the two SSs was found to be duplex layer, composed of inner Cr enriched oxide and outer Fe enriched oxide. However, the inner Cr enriched layer of 310S is more clearly separated from the outer Fe enriched layer than that of SS 316L due primarily to the higher Cr content in SS 310S. The drastic increase in the corrosion potential of SS 310S after 6 h-immersion is closely associated with the growth of the inner Cr enriched oxide layer. The corrosion resistance of SS depends dominantly on the resistance of the inner Cr enriched oxide that is determined form the impedance analysis on the alloy|oxide layer|electrolyte system. The higher corrosion resistance of SS 310S compared with SS 316L results from the more protective inner Cr enriched oxide layer, as confirmed by its higher resistance associated with the higher Cr content in SS 310S.

S100A2 promoter-driven conditionally replicative adenovirus targets non-small-cell lung carcinoma

Lee, K,Yun, S-T,Yun, C-O,Ahn, B-Y,Jo, E-C Macmillan Publishers Limited 2012 Gene Therapy Vol.19 No.10

S100A2, a member of the S100 family of calcium-binding proteins, has been implicated in carcinogenesis as both a tumor suppressor and stimulator. Here, we characterized promoter activity of S100A2, generated an S100A2 promoter-driven conditionally replicative adenovirus (Ad/SA), and evaluated its anti-tumor activity in vitro and in vivo. Promoter activity of S100A2 was greatly restricted to tumor cells, and the S100A2 promoter bound with typical nuclear targets of epidermal growth factor receptor (EGFR) signaling. EGF-stimulated EGFR phosphorylation induced S100A2 expression and further activated E1A expression of Ad/SA, which was restored by EGFR signal inhibition in a concentration-dependent manner in non-small-cell lung carcinoma (NSCLC). In two EGFR-activated tumor xenograft animal models, Ad/SA exhibited potent anti-tumor activity, whereas cetuximab, an EGFR-targeting anticancer drug, was active transiently or ineffective. Combined treatment with cetuximab or cisplatin plus Ad/SA resulted in enhanced anti-tumor activity. Immunohistochemical analysis of tumor sections showed moderate-to-high grade signals for EGFR and adenovirus, and a reduction in viable cells in Ad/SA-treated tumors. Collectively, these results demonstrate that the S100A2 promoter-driven adenovirus is a potent inhibitor of cancers, and further suggest that S100A2 is a target gene of EGFR signaling pathway in NSCLC.

The microRNA miR-124 inhibits vascular smooth muscle cell proliferation by targeting S100 calcium-binding protein A4 (S100A4)

Choe, N.,Kwon, D. H.,Shin, S.,Kim, Y. S.,Kim, Y. K.,Kim, J.,Ahn, Y.,Eom, G. H.,Kook, H. Elsevier Science B.V., Amsterdam. 2017 FEBS letters Vol.591 No.7

<P>S100 calcium-binding protein A4 (S100A4) induces proliferation and migration of vascular smooth muscle cells (VSMCs). We aimed to find the microRNA regulating S100A4 expression. S100A4 transcripts are abruptly increased in the acute phase of carotid arterial injury 1 day later (at day 1) but gradually decreases at days 7 and 14. Bioinformatics analysis reveals that miR-124 targets S100A4. VSMC survival is attenuated by miR-124 mimic but increased by miR-124 inhibitor. miR-124 decreases immediately after carotid arterial injury but dramatically increases at days 7 and 14. miR-124 inhibitor-induced cell proliferation is blocked by S100A4 siRNA, whereas miR-124-induced cell death is recovered by S100A4. Our findings suggest that miR-124 is a novel regulator of VSMC proliferation and may play a role in the development of neointimal proliferation.</P>

Group nearest-neighbor queries in the L₁ plane

Son, W.,Bae, S.W.,Ahn, H.K. North-Holland Pub. Co ; Elsevier Science Ltd 2015 Theoretical computer science Vol.592 No.-

<P>Let P be a set of n points in the plane. The k-nearest-neighbor (abbreviated as k-NN) query problem is to preprocess P into a data structure that quickly reports k closest points in P for a query point q. This paper addresses a generalization of the k-NN query problem to a query set Q of points, namely, the group k-nearest-neighbor query problem, in the L-1 plane. More precisely, a query is assigned with a set Q of at most m points and a positive integer k with k <= n, and the distance between a point p of P and a query set Q is defined as the sum of L-1 distances from p to all q is an element of Q. The maximum number m of query points Q is assumed to be known in advance and to be at most n. In this paper, we propose two algorithms, one based on the range tree and the other based on a data structure for segment dragging queries, and obtain the following complexity bounds: (1) a group k-NN query can be handled in O (T-min log n + (k + m(2))(log logn + logm)) time after preprocessing P using O(m(2)nlog(2)n) space, where T-min = min {k + m, m(2)}, or (2) a group k-NN query can be handled in O ((k + m)log(2) n + m(2)(log(is an element of) n + log m)) time after preprocessing P using O (m(2)n) space, where is an element of > 0 is an arbitrarily small constant. We also show that our approach can be applied to the weighted group k-nearest-neighbor query problem and the group k-farthest-neighbor query problem. (C) 2015 Elsevier B.V. All rights reserved.</P>