Effect of H/Ar treatment on ZnO:B transparent conducting oxide for flexible a-Si:H/μc-Si:H photovoltaic modules under damp heat stress

Jeong, J.S.,Kim, Y.H.,Park, C.K.,Kim, H.D.,Choi, J. Pergamon Press 2016 Microelectronics and reliability Vol.64 No.-

<P>A flexible amorphous/microcrystalline Si:H (a-Si:H/mu c-Si:H) tandem-junction photovoltaic (PV) module was produced in which a thin film of ZnO:B grown by metalorganic chemical vapor deposition (MOCVD) served as the transparent conducting oxide (TCO). The Hall mobility of ZnO:B is degraded by damp heat, simulated here using the conditions of 85 degrees C at 85% relative humidity; this affects the series resistance and efficiency of the PV module. In this study, ZnO:B was treated by H/Ar plasma to reduce the degradation experienced under damp heat. The degradation time of the Hall mobility of ZnO:B, defined as the time necessary for the cell to reach the efficiency loss of -20%, was improved by similar to 54% by H/Ar treatment (ZnO:B center dot H/Ar). The mechanism behind this improvement was investigated by assessing the reactions of the ZnO:B and ZnO:B center dot H/Ar thin films to moisture. Related changes in the physical and chemical properties of ZnO:B and ZnO:B center dot H/Ar were analyzed by Xray photoelectron spectroscopy, secondary-ion mass spectroscopy, and ultraviolet photoelectron spectroscopy. The analyses showed that the concentration of OH- was high while those of Zn2+ and B3+ were low in the grain boundaries of the ZnO:B surface after exposure to humidity. After H/Ar treatment, the increase in OH- concentration in ZnO:B was reduced, and the decrease in the Zn2+ and B3+ concentrations was much smaller. The H/Ar plasma treatment of ZnO:B affected the surface reaction forming Zn(OH)(2), between the OH- and Zn2+ ions at the grain boundaries under damp heat. (C) 2016 Elsevier Ltd. All rights reserved.</P>

광전도체의 CdS 단결정 성장과 물리적 특성

정태수,유평열,신영진,신현길,김택성,정철훈,이훈,신영신,홍광준,유기수 全北大學校 基礎科學硏究所 1994 基礎科學 Vol.16 No.-

승화방법으로 광전도체의 CdS 단결정을 성장하였고 외삽법으로 구한 a_o와 c_o 의 격자상수 값은 각각 4.1318Å과 6.7122Å임을 알았다. Hall 측정값으로 부터 상온에서의 CdS 단결정의 운반자 농도와 이동도는 각각∼10^23m^-3과 2.93×10 exp (-2)㎡/V sec 이였으며 온도에 따른 이동도 변화는 33 K에서 150 K까지는 T^1/2 에 따라 증가하는 경향이 있고 180 K 에서 상온까지는 T^-2에 따라 감소한 경향이 나타났다. 광전류 측정으로 부터 나타난 단파장대의 봉우리는 진성전이에 기인하는 봉우리였으며 이 봉우리의 에너지값은 CdS 광전도체에 에너지 밴드 갭과 동일한 값을 나타냄을 알았다. A CdS single crystal was grown by using sublimation method. Lattice constants, a_o and c_o , obtained by using extrapolation were 4.1318 Å and 6.7122 Å, respectively. The carrier density was∼10^23m^-3 and the mobility was 2.93×10 exp (-2)㎡/V-sec from measured Hall data at room temperature. The mobility has a increasing tendency in proportion to T^1/2 from 33 K to 150 K and a decreasing tendency in proportion to T^-2 from 180 K to room temperature. The short wavelength band peak measured from photocurrent was due to intrinsic transition, and the energy value of this peak was equal to the energy band gap of CdS photoconductor.

Ex situ catalytic upgrading of lignocellulosic biomass components over vanadium contained H-MCM-41 catalysts

Kim, B.S.,Jeong, C.S.,Kim, J.M.,Park, S.B.,Park, S.H.,Jeon, J.K.,Jung, S.C.,Kim, S.C.,Park, Y.K. Elsevier Science Publishers 2016 CATALYSIS TODAY - Vol.265 No.-

<P>H-V-MCM-41 catalysts containing 5, 10, and 30 wt% of vanadium were synthesized and applied to the ex situ catalytic pyrolysis (CP) of three polymeric components of lignocellulosic biomass for the first time. Characterization of the catalysts was performed using N-2 adsorption-desorption, XRD, FT-IR, and NH3-TPD. The results of XRD analysis showed that 5 wt% and 10 wt% H-V-MCM-41 catalysts maintained the mesoporous structure, whereas the mesoporous structure was destroyed in 30 wt% H-V-MCM-41 with considerable amount of small V2O5 crystalline outside the framework. NH3-TPD showed that H-V-MCM-41 has mostly weak acid sites and that 10 wt% H-V-MCM-41 had the largest quantity of acid sites due to framework vanadium. In the case of CP of cellulose using Py-GC/MS, 10 wt% H-V-MCM-41 showed the highest catalytic activity for the production of valuable furanic compounds such as furfural because of the enhanced deoxygenation over the acid sites formed on framework vanadium. In the case of CP of xylan as well, 10 wt% H-V-MCM-41 led to the largest yield of mono-aromatics. The production of acetic acid was also promoted by H-V-MCM-41 catalysts. The CP of lignin over H-V-MCM-41 catalysts promoted substantially the production of important feedstock chemicals for the petrochemical industry: phenolics and mono-aromatics. (C) 2015 Elsevier B.V. All rights reserved.</P>

Targeting the entry region of Hsp90's ATP binding pocket with a novel 6,7-dihydrothieno[3,2-c]pyridin-5(4H)-yl amide

Jeong, J.H.,Oh, Y.J.,Lho, Y.,Park, S.Y.,Liu, K.H.,Ha, E.,Seo, Y.H. S.E.C.T. [etc.] ; Elsevier Science Ltd 2016 European journal of medicinal chemistry Vol.124 No.-

The molecular chaperone Hsp90 plays an important role in cancer cell survival and proliferation by regulating the maturation and stabilization of numerous oncogenic proteins. Due to its potential to simultaneously disable multiple signaling pathways, Hsp90 has emerged as an attractive therapeutic target for cancer treatment. In this study, the design, synthesis, and biological evaluation of a series of Hsp90 inhibitors are described. Among the synthetic compounds, 6,7-dihydrothieno [3,2-c]pyridin-5(4H)-yl amide 19 exhibits a remarkable binding affinity to the N-terminus of Hsp90 in a fluorescence polarization (FP) binding assay (IC<SUB>50</SUB> = 50.3 nM). Furthermore, it effectively inhibits the proliferation of H1975 non-small cell lung cancer (NSCLC) and Skbr3 breast cancer cell lines with GI<SUB>50</SUB> values of 0.31 μM and 0.11 μM, respectively. Compound 19 induces the degradation of the Hsp90 client proteins including EGFR, Her2, Met, c-Raf, and Akt, and consequently promotes apoptotic cancer cell death. Compound 19 also inhibits the growth of H1975 xenografts in NOD-scid IL2R gamma<SUP>null</SUP> mice without any apparent body-weight loss. The immunohistologic evaluation indicates that compound 19 decreases the expression of Akt in xenograft tumor tissue via an inhibition of the Hsp90 chaperon function. Additionally, the cytochrome P450 assay indicates that compound 19 has no effect on the activities of five major P450 isoforms (IC<SUB>50</SUB> > 50 μM for 1A2, 2C9, 2C19, 2D6, and 3A), suggesting that clinical interactions between compound 19 and the substrate drugs of the five major P450 isoforms are not expected. Overall, compound 19 represents a new class of Hsp90 inhibitor with its 6,7-dihydrothieno[3,2-c]pyridin-5(4H)-yl-amide structure, and it has the therapeutic potential to overcome drug resistance in cancer chemotherapy.

Plasma-Enhanced Passivation of a Cu/Ti Bilayer Gate Electrode for an Amorphous Silicon Thin-Film Transistor

T. K. Hong,H. J. Park,D. M. Han,K. H. Jeong,C. S. Kim,C. O. Jeong,J. H. Lee,D. H. Kim,이은구,H. S. Soh,이재갑 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.5

Self-passivated copper as a gate electrode in the form of TiOxNy/Cu/Ti/SiO2 has been obtained by exposing Cu/Ti/SiO2 to mixed of N2/H2 plasma at a low temperature of 300℃. The use of the plasma provides an additional surface heating source, allowing the Ti atoms to outdiffuse to the Cu surface at 300℃ and to react to form a passivation layer on the surface. The H2 plasma transforms the Ti layer into titanium hydride, which effectively inhibits the Cu-Ti reaction and serves as a diffusion barrier against Cu metallization. The TiNxOy/Cu/Ti/SiO2 multilayer formed at the low temperature can be used as a gate electrode in thin-film transistor liquid crystal displays (TFT-LCDs) and exhibits a gate voltage swing of 0.943 V/decade, a threshold voltage of -1.07 V, a mobility of 0.669 cm2/V-s and a Ion/Ioff ratio of 8.18×106. Consequently, this low- temperature plasma processing will allow a reliable passivated gate electrode, which can be utilized in low-temperature amorphous Si thin-film transistor liquid crystal displays, to be formed.

HWE(Hot Wall Epitaxy)에 의한 CuGaSe₂/GaAs epilayer 성장과 광전기적 특성

홍광준,정준우,백형원,정경아,방진주,진윤미,김소형 조선대학교 기초과학연구소 2001 自然科學硏究 Vol.24 No.-

수평 전기로에서 CuGaSe₂ 다결정을 합성하여 HWE(Hot Wall Epitaxy) 방법으로 CuGaSe₂/GaAs epilayer를 반절연성 GaAs(100)기판 위에 성장하였다. CuGaSe₂/GaAs epilayer는 증발원의 온도를 610℃, 기판의 온도를 450℃로 하였다. CuGaSe₂/GaAs epilayer의 결정성의 조사에서 20K에서 광발광(photoluminescence) 스펙트럼이 672.6nm(1.8432eV)에서 엑시톤 방출 스펙트럼이 가장 강하게 나타났으며, 이중결정 X-선 요동곡선(DCRC)의 반폭치(FWHM)도 138 arcsec로 가장 작아 최적 성장 조건임을 알 수 있었다. Hall 효과는 van der Pauw 방법에 의해 측정되었으며, 온도에 의존하는 운반자 농도와 이동도는 293K에서 각각 4.87×10^(23) electron/m³, 1.29×10² m²/v-s 였다. CuGaSe₂/GaAs epilayer의 광전류 단파장대 봉우리들로부터 20K에서 측정된 ΔCr(Crystal field splitting)은 약 0.09 eV ΔSo(spin orbit coupling)는 0.2498 eV였다. 20K의 광발광 측정으로부터 고품질의 결정에서 볼 수 있는 자유 엑시톤 (free exciton)과 매우 강한 세기의 중성 받개(acceptor) 구속 엑시톤 (bound exciton)등의 피크가 관찰되었다. 이때 받개 구속 엑시톤 (bound exciton)의 반치폭과 결합에너지는 각각 8meV와 93.2meV 였다. 또한 Haynes rule에 의해 구한 불순물의 활성화 에너지는 466meV였다. The stochiometric mixture of evaporating materials for the CuGaSe₂/GaAs epilayer was prepared from horizontal furnace. Using extrapolation method of X-ray diffraction patterns for the polycrystal CuGaSe₂, it was found tetragonal structure whose lattice constant a_(0) and c_(0) were 5.615 Å and 11.025 Å, respectively. To obtain the CuGaSe₂/GaAs epilayer, CuGaSe₂ mixed crystal was deposited on throughly etched GaAs(100) by the Hot Wall Epitaxy(HWE) system. The source and substrate temperature were 610 ℃ and 450 ℃ respectively. The crystalline structure of CuGaSe₂/GaAs epilayer was investigated by the double crystal X-ray diffraction(DCXD). Hall effect on this sample was measured by the method of van der pauw and studied on carrier density and mobility depending on temperature. From Hall data, the mobility was likely to be decreased by pizoelectric scattering in the temperature range 30 K to 150 K and by polar optical scattering in the temperature range 150 K to 293 K. From the photocurrent spectra by illumination of polarized light of the CuGaSe₂/GaAs epilaye. We have found that values of spin orbit coupling ΔSo and crystal field splitting ΔCr was 0.0900 eV and 0.2498 eV, respectively. From the photoluminescence measurement of CuGaSe₂/GaAs epilayer, we observed free excition(Ex) observable only in high quality crystal and neutral acceptor-bound exciton (A^(0); X) having very strong peak intensity. And, the full width at half maximum and binding energy of neutral donor bound excition were 8 meV and 93.2 meV, respectively. By Haynes rule, an activation energy of impurity was 466 meV.

Surveillance of avian influenza virus in wild bird fecal samples from South Korea, 2003-2008.

Kang, H M,Jeong, O M,Kim, M C,Kwon, J S,Paek, M R,Choi, J G,Lee, E K,Kim, Y J,Kwon, J H,Lee, Y J [Wildlife Disease Association] 2010 JOURNAL OF WILDLIFE DISEASES Vol.46 No.3

<P>We analyzed the results from nationwide surveillance of avian influenza (AI) from birds in South Korea's major wild bird habitats and the demilitarized zone of South Korea, 2003-2008. Of 28,214 fecal samples analyzed, 225 yielded influenza viruses, for a prevalence of 0.8%. Hemagglutinin (HA) subtypes H1-H12 and all nine neuraminidase (NA) subtypes were detected. The dominant HA subtypes were H6, H1, and H4, and the most common NA subtypes were N2, N1, and N6. Among the 38 HA/NA subtype combinations, the most common were H4N6, H6N1, and H5N2. Thirty-seven low-pathogenic AI (LPAI) viruses of the H5 and H7 subtype were detected. Among them, we identified bird species for 16 H5- and H7-positive fecal samples using a DNA bar-coding system instituted in 2007; all birds were identified as Anseriformes. The HA gene of the H5 wild bird isolates belonged to the Eurasian avian lineage, and could be clearly distinguished from the sublineage H5N1 highly pathogenic AI (HPAI) of the Eurasian and American avian lineages. Whereas H7 LPAI viruses did not group as a separate sublineage with H7 HPAI viruses, H7 isolates were closely related with the Eurasian avian lineage.</P>

Telomere length, TERT and shelterin complex proteins in hepatocellular carcinomas expressing ''stemness''-related markers

Kim, H.,Yoo, J.E.,Cho, J.Y.,Oh, B.K.,Yoon, Y.S.,Han, H.S.,Lee, H.S.,Jang, J.J.,Jeong, S.H.,Kim, J.W.,Park, Y.N. Elsevier Science Publishers 2013 Journal of hepatology Vol.59 No.4

Background & Aims: Hepatocellular carcinomas (HCCs) expressing ''stemness''-related markers have been associated with aggressive biological behavior and poor prognosis. We examined the relationship between ''stemness''-related protein expression and telomere length, hTERT and shelterin complex protein expression and chromosomal instability. Methods: Quantitative fluorescent in situ hybridization for telomere length, immunohistochemistry for K19, EpCAM, CD133, c-kit, HepPar1, hTERT, TRF1, TRF2, POT1, RAP1 and TPP1, and TUNEL assay were performed in 137 HCCs, and array comparative genomic hybridization was performed with 24 HCCs. Results: Telomeres were significantly longer in HCCs expressing ''stemness''-related proteins (K19: p<0.001, EpCAM: p=0.002, CD133: p=0.002). On analyzing different tumor cells within EpCAM-expressing HCCs, EpCAM-positive tumor cells showed longer telomeres (1.329+/-0.246) compared to EpCAM-negative tumor cells (0.996+/-0.381) within the same HCCs (p=0.031). Telomeres were significantly longer in HCCs expressing hTERT (p=0.048) and RAP1 proteins (p=0.031). K19-expressing HCCs expressed hTERT (p=0.002), TRF2 (p=0.001) and TPP1 (p=0.013) more frequently compared to K19-negative HCCs. EpCAM-positivity was associated with more frequent hTERT (p=0.028), TPP1 (p=0.017), TRF2 (p=0.027) and POT1 (p=0.004) expression. Copy number alterations were more frequent in K19 and EpCAM-expressing HCCs compared to HCCs without these markers (K19: p=0.038, EpCAM: p=0.009). HCCs with longer telomeres were associated with a shorter overall (p=0.019) and disease-free survivals (p=0.049), and decreased disease-free survivals were seen in TRF2-positive HCCs (p=0.018). Conclusions: HCCs expressing ''stemness''-related proteins are characterized by increased telomere length, increased expression of hTERT and shelterin complex proteins, and increased chromosomal instability compared to conventional HCCs. Longer telomeres and TRF2 expression in HCCs are associated with poor patient outcomes.

Cordyceptin induces apoptosis through repressing hTERT expression and inducing extranuclear export of hTERT

Jang, K.J.,Kwon, G.S.,Jeong, J.W.,Kim, C.H.,Yoon, H.M.,Kim, G.Y.,Shim, J.H.,Moon, S.K.,Kim, W.J.,Choi, Y.H. Society for Bioscience and Bioengineering, Japan ; 2015 Journal of bioscience and bioengineering Vol.119 No.3

Cordycepin is an adenosine analog originally extracted from Cordyceps militaris that possesses many pharmacological effects including immune activation and antioxidant and antitumor effects. However, the underlying relationship between apoptosis and telomerase activity in response to cordycepin exposure has not been investigated. In this study, we found that cordycepin-induced apoptosis of human leukemia cells (H937 and THP-1 cells) was associated with inactivation of telomerase and downregulation of human telomerase reverse transcriptase (hTERT) as well as the transcription factors c-Myc and Sp1, which are required for basal transcription from the hTERT gene promoter. Cordycepin also attenuated the activation of phosphoinositide-3-kinase (PI3K)/Akt signaling, thereby reducing phosphorylation and nuclear translocation of hTERT. We further showed that the PI3K inhibitor LY29004 significantly decreased telomerase activity in cordycepin-treated cells and increased cordycepin-induced cell death. These findings demonstrate that cordycepin is cytotoxic to human leukemia cells and suppresses telomerase activity through transcriptional and post-translational suppression of hTERT by inactivating the PI3K/Akt signaling pathway.

Bactericidal effect through non-uptake pathway with photofunctional silicon polymer that generates reactive oxygen species

Wang, K.K.,Jung, S.J.,Hwang, J.W.,Kim, B.J.,Kim, D.H.,Bae, I.K.,Jeong, S.H.,Kim, Y.R. Elsevier Sequoia 2016 Journal of photochemistry and photobiology Chemist Vol.315 No.-

<P>We report bactericidal effect of photosensitizer (H2TPP: 5,10,15,20-tetraphenyl-21H,23H-porphyrin) through non-uptake pathway and efficacy of the photofunctional silicon polymer to the decomposition of the formed biofilm and the suppression of the biofilm formation. The photoftmctional silicon polymer (PSP), which is the silicon polymer embedded with a photosensitizer, is fabricated by a simple solvent swell-encapsulation-shrink method. Reactive oxygen generation from PSP was confirmed by using the decomposition reaction of 1,3-diphnyl-isobenzofuran (DPBF). Also, singlet oxygen generation which is one of the reactive oxygen species (ROS) from PSP is directly confirmed with time and wavelength resolved singlet oxygen phosphorescence spectroscopy. For the influence study of ROS under the non-uptake condition of photosensitizer (PS to bacteria), photodynamic inactivation (PDI) effect of PSP is evaluated for Gram-positive, Gram-negative bacteria, and fungi. Those microorganisms were inactivated by PSP within 1 h under the given power of laser light (63.7 mW/cm(2)). Among the bacteria, especially, Staphylococcus aureus as the Gram-positive bacteria were completely disinfected under the given experimental condition. Furthermore, PSP successfully demonstrates the decomposition of the formed biofilm and the suppression of the biofilm formation with green light emitting diode (GLED, 3.5 mW/cm(2),lambda(max) = 517 nm, FWHM = 37 nm), which shows the practical application possibility of bactericidal material. (C) 2015 Elsevier B.V. All rights reserved.</P>