• Current Photovoltaic Research
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• v.2 no.3
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• pp.103-109
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• 2014

Highly efficient hydrogenated nanocrystalline silicon (nc-Si:H) thin-film solar cells were prepared on flexible stainless steel substrates using plasma-enhanced chemical vapor deposition. To enhance the performance of solar cells, material properties of back reflectors, n-doped seed layers and wide bandgap nc-SiC:H window layers were optimized. The light scattering efficiency of Ag back reflectors was improved by increasing the surface roughness of the films deposited at elevated substrate temperatures. Using the n-doped seed layers with high crystallinity, the initial crystal growth of intrinsic nc-Si:H absorber layers was improved, resulting in the elimination of the defect-dense amorphous regions at the n/i interfaces. The nc-SiC:H window layers with high bandgap over 2.2 eV were deposited under high hydrogen dilution conditions. The vertical current flow of the films was enhanced by the formation of Si nanocrystallites in the amorphous SiC:H matrix. Under optimized conditions, a high conversion efficiency of 9.13% ($V_{oc}=0.52$, $J_{sc}=25.45mA/cm^2$, FF = 0.69) was achieved for the flexible nc-Si:H thin-film solar cells.

• Bulletin of the Korean Chemical Society
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• v.31 no.10
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• pp.2923-2928
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• 2010

This study examined the synthesis of the crystal structure of bis(2,2'-bipyridine)nitrato zinc (II) nitrate, $[Zn(bipy)_2(NO_3)]^+NO_3^-$ using a microwave treatment at 300 W and 60 Hz for the application to dye-sensitized solar cells. The simulated complex structure of the complex was optimized with the density functional theory calculations for the UV-vis spectrum of the ground state using Gaussian 03 at the B3LYP/LANL2DZ level. The structure of the acquired complex was expected a penta-coordination with four nitrogen atoms of bipyridine and the oxygen bond of the $NO_3^-$ ion. The reflectance UV-vis absorption spectra exhibited two absorptions (L-L transfers) that were assigned to the transfers from the ligand ($\sigma$, $\pi$) of $NO_3$ to the ligand ($\sigma^*$, $\pi^*$) of pyridine at around 200 - 350 nm, and from the non-bonding orbital (n) of O in $NO_3$ to the p-orbital of pyridine at around 450 - 550 nm, respectively. The photoelectric efficiency was approximately 0.397% in the dye-sensitized solar cells with the nanometer-sized $TiO_2$ at an open-circuit voltage (Voc) of 0.39 V, a short-circuit current density (Jsc) of $1.79\;mA/cm^2$, and an incident light intensity of $100\;mW/cm^2$.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.75.2-75.2
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• 2013

Atomic layer deposition (ALD), utilizing self-limiting surface reactions, could offer promising perspectives for future efficient energy conversion devices. The capabilities of ALD for surface/interface modification and construction of novel architectures with sub-nanometer precision and exceptional conformality over high aspect ratio make it more valuable than any other deposition methods in nanoscale science and technology. In the context, a variety of researches on fabrication of active materials for energy conversion applications by ALD are emerging. Among those materials, one-dimensional nanotubular titanium dioxide, providing not only high specific surface area but also efficient carrier transport pathway, is a class of the most intensively explored materials for energy conversion systems, such as photovoltaic cells and photo/electrochemical devices. The monodisperse, stoichiometric, anatase, TiO2 nanotubes with smooth surface morphology and controlled wall thickness were fabricated via low-temperature template-directed ALD followed by subsequent annealing. The ALD-grown, anatase, TiO2 nanotubes in alumina template show unusual crystal growth behavior which allows to form remarkably large grains along axial direction over certain wall thickness. We also fabricated dye-sensitized solar cells (DSCs) introducing our anatase TiO2 nanotubes as photoanodes, and studied the effect of blocking layer, TiO2 thin films formed by ALD, on overall device efficiency. The photon convertsion efficiency ~7% were measured for our TiO2 nanotubebased DSCs with blocking layers, which is ~1% higher than ones without blocking layer. We also performed open circuit voltage decay measurement to estimate recombination rate in our cells, which is 3 times longer than conventional nanoparticulate photoanodes. The high efficiency of our ALD-grown, anatase, TiO2 nanotube-based DSCs may be attributed to both enhanced charge transport property of our TiO2 nanotubes photoanode and the suppression of recombination at the interface between transparent conducting electrode and iodine electrolytes by blocking layer.

• The Journal of Internal Korean Medicine
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• v.21 no.1
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• pp.65-73
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• 2000

Objectives : The effects of cotreatment of adriamycin and ethanol extract of herb (Palgin-tang hab Hwajuck-hwan a traditional medicine for cancer treatment in oriental medicine) on the induction of apoptotic cell death were investigated in human liver origin cell lines, Chang. Methods : Chang(ATCC) liver cells were cultured in RPMI-1640(Gibco SRL Co, Gaithersburg, MD) badge including 10% fetal bovine serum. Chang liver cells were treated with various concentrations(from 10 to $0.16{\mu}l$) of adriamycin and herb extract(from 500 to $31.25{\mu}l$) After 48h later, the cells were tested for viability by Crystal violet staining assay. Adriamycin and Herb extract induced ladder pattern of DNA fragmentation in Chang cells. Genomic DNA was isolated and separated on 1.5% agarose gels. The DNA was stained with ethidium bromide and visualized under UV light. Results : The death of Chang cells was synergistically induced by the cotreatment of adriamycin and ethanol extract of herb. In addition, the cotreatment-induced cell death of Chang cells was mediated by apoptotic death signal processes. The phosphotransferase activity of JNK1 remained in a basal level in Chang cells which was treated individually with the adriamycin and ethanol extract of herb. However, it was markedly increased in Chang cells which was cotreated with adriamycin and ethanol extract of herb. In addition, the expression of Fas and FasL was markedly induced by the cotreatment of adriamycin and herb extract. For a while, the expression of Sax was a eminently increased by the ethanol extract of herb. However, Scl2 expression was not affected by the individual or cotreatment of adriamycin and herb extract. Conclusions : our results suggest that the cotreatment of adriamycin aM ethanol extract of herb induces synergistic apoptotis of human liver origin Chang cells via the upregulation of JNK, Fas, FasL and Bax.

• The korean journal of orthodontics
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• v.27 no.6 s.65
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• pp.929-941
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• 1997

Optimal force for orthodontic treatment is the force that produces a rapid rate of tooth movement without discomfort to the Patient or ensuing tissue damage. Recently considerable interest has been generated in the application of magnets as a way to obtain an optimal force. The purpose of the present study was to investigate the effect of static magnetic fields of Sm-Co magnets on molecular and cellular activities. The distance of erythrocyte sedimentation was measured directly, and the activities and the syntheses of $Fe^{2+}$-related enzymes (catalase and NO synthase) and non $Fe^{2+}$-related enzyme (lactic dehydrogenase) were assayed by the spectrophotometer. The growth and the proliferation of osteoblast-like cells $MC_3T_3-E_1$ were determined by the crystal violet staining and the ${^3}H$-thymidine incorporation. The erythrocytes were exposed to the pole face flux density of 1,400 G (gauss), and the enzymes and osteoblast-like cells $MC_{3}T_3-E_1$ were exposed to the flux density of 7,000 G. The results obtained were as follows: 1. The distance of sedimentation of erythrocyte was not affected by the static magnetic fields. 2. The activities of catalase and lactic dehydrogenase were not affected by the static magnetic fields. 3. The intracellular syntheses of NO synthase and lactic dehydrogenase were not affected by the static magnetic fields. 4. The growth and the proliferation of cultured osteoblast-like cells $MC_{3}T_3-E_1$ were not affected by the static magnetic fields. These results suggested that the molecular and cellular activities were not significantly influenced by the static magnetic fields.

• Archives of Plastic Surgery
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• v.37 no.4
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• pp.340-345
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• 2010

Purpose: Recently, bioceramics have become popular as a substitute graft material for reconstruction of bony defect after trauma or tumor surgery. Among the bioceramic materials, hydroxyapatite (HA) is favored due to its biocompatibility. HA scaffold is composed of the interconnected reticular framework, macropores and micropores. Macropores play an important role in cell migration, nutrients supply and vascular ingrowth. On the other hand, a number of micropores less than $10{\mu}m$ form an irregular surface on HA scaffolds, which prevents the osteoblast from adhering and proliferating on the surface of HA scaffold. Methods: In this study, three different groups were designed for comparison. In the first group (group A), conventional method was used, in which HA pellet was applied without surface pretreatment. The second group (group B) was given a HA pellet that has been coated with crystalline HA solution prior to application. In the third group (group C), the same method was used as the second group, where the pretreated HA pellet was heated ($1250^{\circ}C$, 1 hour) before application. Osteoblast-like cells ($2{\times}10^4$/mL) were scattered onto every pellet, then they were incubated in 5% $CO_2$ incubator at $37^{\circ}C$ for twelve days. During the first three days, osteoblast cells were counted using the hemocytometer daily. ALP activity was measured on the 3, 6, 9 and 12 culture days using the spectrophotometer. Results: Under SEM, group A showed a surface with numerous micropores, and group B revealed more rough crystal surface. Group C revealed a fused crystal appearance and flattened smooth surface. In proliferation and ALP activity of osteoblast cells, group C showed better results compared to group B. Group A which lacks pretreatment of the surface showed less osteoblast proliferation and ALP activity than group C, but showed better results than group B. Conclusion: We found that crystallized HA with heat treatment method enhances the osteoblasts proliferation and differentiation on the surface of HA pellets.

• Korean Journal of Clinical Laboratory Science
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• v.51 no.3
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• pp.379-385
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• 2019

Osteoporosis is a disease that increases the risk of fractures by inducing a decrease in bone strength by the changes in hormones and a decrease in minerals. Recent reports have indicated that the long-term administration of Adefovir dipivoxil (ADV), which is used as a treatment for the hepatitis virus and AIDS, may have osteoporotic side effects. On the other hand, there are few studies on the cytopathic correlation of these causes. In this study, the biological relevance of ADV was evaluated using osteoblast hFOB1.19 and vascular endothelial cell HUVEC. First, the cells were treated with ADV at different concentrations, and DAPI and crystal violet staining were performed for morphological analysis of each cell and nucleus. A CCK-8 assay, real-time PCR, alkaline phosphatase (ALP) staining, and activity was performed to evaluate the drug effects on cell proliferation, gene expression, and osteoblast differentiation. As a result, ADV induced cell hypertrophy in hFOB1.19 cells and HUVEC cells. Furthermore, ADV not only inhibited cell proliferation and TGF-${\beta}$ expression but was also involved in osteoblast differentiation. Overall, these results provide basic data to help better understand the mechanism of ADV-induced osteoporosis and its clinical implications.

• Journal of Microbiology and Biotechnology
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• v.28 no.1
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• pp.77-86
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• 2018

The human pathogen and food spoiler Bacillus cereus can form biofilms that act as a persistent source of contamination, which is of public health concern. This study aimed to understand how the source of isolation might affect the behavior of biofilm formation. Biofilm formation abilities of 56 strains of B. cereus isolated from different environments, including human food poisoning, farm, and food, were determined. Crystal violet assay results revealed significant (p < 0.05) differences in biofilm formation abilities among the strains isolated from different sources only at an early stage of incubation. However, strain origin showed no impact on later stage of biofilm formation. Next, correlation of the group of isolates on the basis of their biofilm-forming abilities with the number of sessile cells, sporulation, and extracellular polymeric substance (EPS) formation was determined. The number of sessile cells and spores in biofilms was greatly influenced by the groups of isolates that formed dense, moderate, and weak biofilms. The contribution of extracellular DNA and/or proteins to EPS formation was also positively correlated with biofilm formation abilities. Our results that the source of isolation had significant impact on biofilm formation might provide important information to develop strategies to control B. cereus biofilm formation.

• Natural Product Sciences
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• v.2 no.2
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• pp.130-136
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• 1996

Evaluation of plant extracts that might inhibit hepatitis B virus (HBV) replication was performed to find potent anti-HBV agents. Eighty-five species of plants from forty-three families were tested for their anti-HBV activities using HBV-producing HepG2-derived 2.2.15 cells. The anti-HBV activity of plant extracts was measured by slot blot hybridization technique and cytotoxicity was determined by crystal violet staining procedure. All plants were extracted with methanol and the extracts were partitioned into n-hexane, ethyl acetate and aqueous layer. The ethyl acetate fractions of Rhus verniciflua $(stem:\;EC_{50},\;8.2{\mu}g/ml;\;CC_{50},\;9.4{\mu}g/ml)$, Gastrodia elata $(root:\;EC_{50},\;17.7{\mu}g/ml;\;CC_{50},\;>20{\mu}g/ml)$, Raphanus sativus $(seeds:\;EC_{50},\;17.3{\mu}g/ml;\;CC_{50},\;>20{\mu}g/ml)$, and Angelica gigas $(root:\;EC_{50},\;8.3{\mu}g/ml;\;CC_{50},\;15.6{\mu}g/ml)$ revealed the anti-HBV activity in 2.2.15 cell culture system and these fractions are under the process of further sequential fractionation by column chromatography to find the active principles against HBV.

• The Journal of Korean Medicine
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• v.21 no.4
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• pp.183-192
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• 2000

Objectives : The present study was carried out to investigate the effects of Danchun-hwan(DCH) on the peroxynitrite-induced neural cell death in human neuroblastoma cell line, SH-SY5Y. Methods : The cultured cells were pretreated with DCH and exposed to 3-morpholinosydnonimine(SIN-1) that simultaneously generates NO and superoxide, thus possibly forming peroxynitrite. The cell damage was assessed by using MTT assay and crystal violet staining. Results : Exposure of the cells to SIN-1 for 24hr induced 75% apoptotic cell death, as evaluated by the occurrence of morphological nuclear changes characteristic of apoptosis using 4', 6-diamidino-2-phenylinole(DAPI). However, pretreatment of SH-SY5Y with the water extracts of DCH, inhibited the apoptotic cell death in a dose-dependent manner. DCH also inhibited SIN-1-induced apoptotic caspase 3-like protease activity in a dose-dependent manner. DCH recovered the depleted glutathione levels by SIN-1. Conclusions : Taken together, it is suggested that DCH protected human neuroblastoma cell line, SH-SY5Y, from the free radical injury mediated by peroxynitrite by a mechanism of elevating antioxidant, GSH.