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HWE(Hot Wall Epitaxy)에 의한 ZnIn_2S_4 박막 성장과 광전도 특성
홍광준,이관교,정준우,정경아,방진주,장현규,문종대,김혜숙 조선대학교 기초과학연구소 1999 自然科學硏究 Vol.22 No.1
HWE 방법에 의해 ZnIn_2S_4 박막을 Si(00) 기판 위에 성장시켰다. 증발원과 기판의 온도를 각각 610℃, 450℃로 하여 성장시킨 ZnIn_2S_4 박막의 이중 결정 X-선 요동곡선(DCRC)의 반폭치(FWHM)값이 245 arcsec로 가장 작았다. Van der Pauw 방법으로 Hall 효과를 측정하여 운반자농도의 1n n 대 1/T에서 구한 활성화에너지는 0.17eV로 측정되었다. Hall 이동도의 온도 의존성은 30K에서 100K까지는 불순물산란에 기인하고, 100K에서 293K까지는 격자산란에 기인한것으로 고찰되었다. 광전도셀의 특성으로 spectral response, 최대 허용소비전력(MAPD), 광전류와 암전류(pc/dc)의 비 및 응답시간을 측정하였다. S 증기분위기에서 열처리한 광전도 셀의 경우, 감도(??)는 0.99, pc/dc은 1.37x10^7, 그리고 최대 허용소비전력(MAPD)은 336mW, 오름시간(rise time)은 9ms, 내림시간(decay time)은 9.8ms로 가장 좋은 광전도 특성을 얻었다. The ZnIn_2S_4 thin films were grown on the Si(100) wafers by a hot wall epitaxy method(HWE). The source and substrate temperature are 610℃ and 450℃ respectively. The crystalline structure of epilayers was investigated by double crystal X-ray diffraction(DCXD). Hall effect on the sample was measured by the van der Pauw method and studied on the carrier density and mobility dependence on temperature. From Hall data, the mobility was increased in the temperature range 30K to 100K by impurity scattering and decreased in the temperature range 100K to 293K by the lattice scattering. In order to explore the applicability as a photoconductive cell, we measured the sensitivity(??), the ratio of photocurrent to darkcurrent(pc/dc), maximum allowable power dissipation(MAPD), spectral response and response time. The results indicated that the photoconductive characteristic were the best for the samples annealed in S vapor compare with in Zn, In, air and vacuum vapour. Then we obtained the sensitivity of 0.99, the value of pc/dc of 1.37x10^7, the MAPD of 336mW, and the rise and decay time of 9ms and 9.8ms, respectively.
Effect of PVP molecular weight on the formation of Ag nanoparticles on echinoid-like TiO<sub>2</sub>
Jang, I.,Song, K.,Park, J.H.,Kim, M.,Kim, D.W.,Oh, S.G. North-Holland 2013 Materials letters Vol.96 No.-
Ag nanoparticles were immobilized on echinoid-like TiO<SUB>2</SUB> particles via an alcohol reduction process with poly(vinyl pyrrolidone) (PVP) of different molecular weights (Mw.). The sizes of Ag nanoparticles prepared by using PVP K15 (Mw.: 10,000) and K30 (Mw.: 40,000) were 12-15nm and 19-31nm, respectively. On the other hand, Ag nanoparticles were not observed when PVP K12 (Mw.: 3500) was used. The crystal structure of Ag nanoparticles formed on TiO<SUB>2</SUB> was face-centered cubic silver phase and the chemical states of Ag nanoparticles were Ag<SUP>+</SUP> and Ag<SUP>0</SUP>. The photocatalytic performance was enhanced by Ag deposition. Among the samples, the prepared Ag/TiO<SUB>2</SUB> composite by using PVP K15 exhibited better photocatalytic activity than other composites due to its higher Ag coverage on the TiO<SUB>2</SUB> surface.
Phospholipase D-mediated autophagic regulation is a potential target for cancer therapy
Jang, Y H,Choi, K Y,Min, D S Macmillan Publishers Limited 2014 Cell death and differentiation Vol.21 No.4
Autophagy is a catabolic process in which cell components are degraded to maintain cellular homeostasis by nutrient limitations. Defects of autophagy are involved in numerous diseases, including cancer. Here, we demonstrate a new role of phospholipase D (PLD) as a regulator of autophagy. PLD inhibition enhances autophagic flux via ATG1 (ULK1), ATG5 and ATG7, which are essential autophagy gene products critical for autophagosome formation. Moreover, PLD suppresses autophagy by differentially modulating phosphorylation of ULK1 mediated by mTOR and adenosine monophosphate-activated protein kinase (AMPK), and by suppressing the interaction of Beclin 1 with vacuolar-sorting protein 34 (Vps34), indicating that PLD coordinates major players of the autophagic pathway, AMPK-mTOR-ULK1 and Vps34/Beclin 1. Ultimately, PLD inhibition significantly sensitized in vitro and in vivo cancer regression via genetic and pharmacological inhibition of autophagy, providing rationale for a new therapeutic approach to enhancing the anticancer efficacy of PLD inhibition. Collectively, we show a novel role for PLD in the molecular machinery regulating autophagy.
A Study of Ferroelectric Properties in NaxK1xNbO3 Ceramic Compounds
D.H. Cho,M.S. Jang,조채용,J.G. Choi,J.P. Kim,M.K. Ryu,S.S. Park,S.Y. Cho 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.1
The dielectric properties and the behavior of phase transition in the NaxK1xNbO3 ceramic system were investigated. The temperature and composition parameter (x ) dependence of the dielectric constants and the loss tangent of the system were measured. The dielectric constant was the highest and the loss tangent of the sample was the lowest at x = 0.52. The dielectric constant of Na0:52K0:48NbO3 ceramics becomes broadened and the transition temperature shifts toward a higher temperature with an increase in the measuring frequency at the Curie temperature. The remanent polarization (Pr) and coercive eld (Ec) were obtained from the D-E hysteresis loop at room temperature. A typical hysteresis loop of a sample of composition parameter x = 0.52 exhibits a remanent polarization of 10 C/cm2 and a coercive eld of 8.4 kV/cm.
Shin, D.J.,Park, J.Y.,Jang, Y.Y.,Lee, J.J.,Lee, Y.K.,Shin, M.G.,Jung, J.Y.,Carson, W.E.,Cho, D.,Kim, S.K. Elsevier 2013 Veterinary immunology and immunopathology Vol.153 No.3
Canine NK cells still are not well-characterized due to the lack of information concerning specific NK cell markers and the fact that NK cells are not an abundant cell population. In this study, we selectively expanded the canine cytotoxic large granular lymphocytes (CLGLs) that exhibit morphologic, genetic, and functional characteristics of NK cells from normal donor PBMCs. The cultured CLGLs were characterized by a high proportion of CD5(dim) expressing cells, of which the majority of cells co-expressed CD3 and CD8, but did not express TCRαβ and TCRγδ. The phenotype of the majority of the CLGLs was CD5(dim)CD3<SUP>+</SUP>CD8<SUP>+</SUP> TCRαβ<SUP>-</SUP>TCRγδ<SUP>-</SUP>CD4<SUP>-</SUP>CD21<SUP>-</SUP>CD11c<SUP>+/-</SUP>CD11d<SUP>+/-</SUP>CD44<SUP>+</SUP>. The expression of mRNAs for NK cell-associated receptors (NKG2D, NKp30, NKp44, Ly49, perforin, and granzyme B) were highly upregulated in cultured CLGLs. Specifically, NKp46 was remarkably upregulated in the cultured CLGLs compared to PBMCs. The mRNAs for the NKT-associated iTCRα gene in CLGLs was present at a basal level. The cytotoxic activity of the CLGLs against canine NK cell-sensitive CTAC cells was remarkably elevated in a dose-dependent manner, and the CLGLs produced large amounts of IFN-γ. The antitumor activity of CLGLs extended to different types of canine tumor cells (CF41.Mg and K9TCC-pu-AXC) without specific antigen recognition. These results are consistent with prior reports, and strongly suggest that the selectively expanded CLGLs represent a population of canine NK cells. The results of this study will contribute to future research on canine NK cells as well as NK cell-based immunotherapy.
Shinde, K. P.,Jang, S. H.,Kim, J. W.,Kim, D. S.,Ranot, M.,Chung, K. C. The Royal Society of Chemistry 2015 Dalton transactions Vol.44 No.47
<P>We report for the first time the synthesis of nanopowders of TbN, DyN and HoN crystallized in a cubic structure by the plasma arc discharge (PAD) method and investigate their magnetocaloric properties for magnetic refrigeration applications. The nitridization of terbium, dysprosium and holmium was obtained using a mixture of nitrogen and argon gas inside a discharge chamber with 4 kPa pressure. The structural and microstructural properties of these rare earth nitrides were investigated by using X-ray diffraction and transmission electron microscopy. The studied nitrides undergo a second-order ferromagnetic to paramagnetic phase transition at Curie temperatures of 35.7, 19.9 and 14.2 K for TbN, DyN and HoN, respectively. The magnetocaloric effects were estimated by calculating the magnetic entropy changes from the magnetization data sets measured at the different applied magnetic fields and temperatures. The changes in entropy −Δ<I>S</I><SUB>M</SUB> were found to be 12.0, 13.6 and 24.5 J kg<SUP>−1</SUP> K<SUP>−1</SUP> at an applied magnetic field of 5 T.</P> <P>Graphic Abstract</P><P>We report for the first time the synthesis of nanopowders of TbN, DyN and HoN crystallized in a cubic structure by the plasma arc discharge (PAD) method and investigate their magnetocaloric properties for magnetic refrigeration applications. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c5dt03528g'> </P>
고관영,허주환,문정효,장재석,김동윤,정민섭,김주찬,박기용,이강연,조명우,이권진,조영호,이효걸,김주호,이경희 울산과학대학 2000 연구논문집 Vol.27 No.1
본 논문에서는 기존의 Motion-JPEG 기반 감시시스템에서 낮은 동영상 압축성능 문제를 해결하기 위한 새로운 동영상 압축기법을 제안하였다. 제안된 방법에서는 현재 프레임의 JPEG 데이터 중 변화된 압축 데이터만이 실시간으로 추출하고 저장된다. 제안된 방법에 의해 저장된 데이터는 기존의 JPEG과는 다른 고유의 포맷을 가지기 때문에, 동영상 데이터는 더욱 안전하게 유지될 수 있다. 실험을 통해, 제안된 동영상 압축기법의 압축률이 기존의 Motion-JPEG 기반 감시시스템에 비해 3배정도 높다는 것을 확인할 수 있었다.