• 한국신재생에너지학회:학술대회논문집
• /
• 2007.11a
• /
• pp.318-321
• /
• 2007

CdSe nanoparticles were prepared by chemical solution methods using $CdCl_2{\cdot}4H_2O$ (or $Cd(NO_3)_ 2{\cdot}4H_2O$) and $Na_2SeSO_3$. The characteristics of CdSe nanoparticles were controlled by the react ion time, reaction temperature and reaction method as well as the surfactants. Cetyltrimethyl ammonium bromide(CTAB) was used as a capping agent to control the chemical reactions in aqueous solution. Polyvinylalcohol(PVA) was used as a templet in sono-chemical method. CdSe nanoparticles synthesized in aqueous solution showed homogeneous size distribution with relatively stable surface. CdSe nanoparticles synthesized in non-aqueous solution containing diethanolamine(DEA) showed the structure transformation from cubic to hexagonal as the reduction temperature increased from 80 to $160^{\circ}C$. Core shell CdSe was synthesized by sono-chemical method. Characteristics of CdSe nanoparticles were analyzed using transmission electron microscopy(TEM), x-ray photoelectron spectroscopy(XPS), x-ray diffraction(XRD), UV-Vis absorption spectra, fourier transform infrared spectroscopy(FT-IR) and photoluminescence spectra spectroscopy(PL). This paper presents simple routes to prepare CdSe nanoparticles for solar cell applications.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.10
• /
• pp.2909-2912
• /
• 2010

Hydrogenated microcrystalline silicon (${\mu}c$-Si:H) thin film for solar cells is prepared by plasma-enhanced chemical vapor deposition and physical properties of the ${\mu}c$-Si:H p-layer has been investigated. With respect to stable efficiency, this film is expected to surpass the performance of conventional amorphous silicon based solar cells and very soon be a close competitor to other thin film photovoltaic materials. Silicon in various structural forms has a direct effect on the efficiency of solar cell devices with different electron mobility and photon conversion. A Raman microscope is adopted to study the degree of crystallinity of Si film by analyzing the integrated intensity peaks at 480, 510 and $520\;cm^{-1}$, which corresponds to the amorphous phase (a-Si:H), microcrystalline (${\mu}c$-Si:H) and large crystals (c-Si), respectively. The crystal volume fraction is calculated from the ratio of the crystalline and the amorphous phase. The results are compared with high-resolution transmission electron microscopy (HR-TEM) for the determination of crystallinity factor. Optical properties such as refractive index, extinction coefficient, and band gap are studied with reflectance spectra.

• Journal of Hydrogen and New Energy
• /
• v.23 no.3
• /
• pp.256-263
• /
• 2012

We studied the degradation phenomenon of Pt catalyst in PEMFC. We used the electron microscope analysis technique including the ultra-microtome pretreatment method, FEG-SEM and TEM analysis methods for analysis of Pt nanoparticles. The Pt catalyst degradation is observed not only in electrode site but also in membrane site. We investigated these various degradation phenomena. The cathode electrode layer thickness is reduced. The size of the catalyst is increased much larger than initial size in membrane site. The catalyst moved from electrode layer to the electrolyte membrane. The rounded shape of catalyst was changed to the polygon. As a result, we found that the catalyst degradation processes of migration and coarsening occurred by the followings mechanisms; (1) dissolution of Pt ; (2) diffusion of Pt ion ; (3) Pt ion chemical reduction in membrane; (4) Coarsening of Pt particles (Ostwald ripening) ; (5) polygon shape change of Pt by {111} plane growth.

• Journal of Haehwa Medicine
• /
• v.8 no.1
• /
• pp.115-129
• /
• 1999

To evaluate radioprotective effects of Kamisagoonjatang(KST), Kamijihwangtang (KJT) and Kamigoonjajihwangtang(KKJT), studies were done experimentally. The results were obtained as follows: 1. By FACS analysis after exposure to radiation by Liniac, T cell and T-helper cell were significantly increased in KST treated group and also B cell and macrophage in KJT treated group while splenocytes were significantly decreased in control group. 2. WBC, PLT were significantly increased in KKJT treated group as compared with control group after exposure to radiation by Liniac. 3. In histological changes of jejunum of $BALB{\backslash}C$ mice after after exposure to radiation by Liniac, exclusion and fusion of villi were decreased in all groups as compared with control group. 4. In the observation of morphological changes by SEM and TEM after radiation by Liniac, KKJT, KJT and KST inhibited demage of internal structures such as mitochondria, ESR and golgi of jejunum cells in order as compared with control group. From above results it was concluded that KJT, KST and KKJT could be usefully applied for protection from damage by radiotherapy to cancer.

• Journal of Haehwa Medicine
• /
• v.5 no.2
• /
• pp.523-533
• /
• 1997

Ursolic acid(UA) was isolated from Oldenlandiae diffusae Herba, one of the commonly used medicinal herbs for the treatment of cancer. IC50 of UA against cancer cell lines as SNU-1, B16-Fo. SK-OV3, HCT15, XF498, SK-MEL and A549 was $6{\mu}g/ml$, 4$4.4{\mu}g/ml$, $4.5{\mu}g/ml$, $4.6{\mu}g/ml$ and $4.2{\mu}g/ml$ respectively suggesting cytotoxicity against cancer cells. DNA fragmentation was expressed from the concnetration of $5.5{\mu}g/ml$ of UA by agarose electrphoresis. In the observation of morphological changes by phase contrast microscope, SEM and TEM, cell injury and condensation of cytoplasm from nucleus began 4 hr after UA treatment. fragmentaion of nucleus and injury of cell membrane was shown 24 hr after UA treatmeilt with SNU-1 cells. Aurin tricarboxic acid as endonuclease inhibitor. and nicotinamide as poly(ADP-ribose) polymerase inhibitor protected over 50% of cytotoxicity of UA against SNU-1 was at the concentrations of $3{\mu}M$ and $300{\mu}M$ respectively suggesting UA acts on nucleus. These results suggest that UA had antimetastatic effect and induced apoptosis.

• Journal of Hydrogen and New Energy
• /
• v.27 no.3
• /
• pp.270-275
• /
• 2016

A simple solid state incorporation method was employed in order to incorporate Pd nanocatalyst into a Nafion film for polymer electrolyte membrane fuel cell (PEMFC) via the reduction of palladium (II) bis (acetylacetonate), $Pd(acac)_2$. It was sublimed, penetrated into Nafion film and then reduced to Pd nanoparticles simultaneously in a glass reactor of N2 atmosphere at $180^{\circ}C$ for 1, 3 and 5 min. This reaction was took place without any reducing agent and any solvent. The morphology of the Pd nanoparticles was observed by transmission electron microscopy (TEM), and Pd distribution was analyzed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). And 23% modification of tensile strength of Pd/Nafion composite film was measured by universal testing machine and I-V curve was estimated by using a unit cell with $5{\times}5cm^2$ active area.

• Advances in nano research
• /
• v.11 no.6
• /
• pp.657-665
• /
• 2021

The present work aimed to explore green approach via aqueous leaves extract of Murraya koenigii (ALEMk) for the synthesis of silver nanoparticles (AgNPsMk) in single step. The synthesis process was visualized with a color change and monitored by employing UV/Visible spectroscopy and a clear peak attained at 420 nm confirming the synthesis of AgNPsMk. The possible functional groups present in the extract which participated in the synthesis of AgNPsMk were identified with the help of FTIR spectroscopy. Further characterization using TEM images revealed the spherical shape of AgNPsMk with average particle size of 20 nm displaying well dispersion throughout the solution. Pronounced antioxidant activities of AgNPsMk at increased concentrations observed which evidencing strong radical scavenging ability. Moreover, AgNPsMk exhibited strong antibacterial behavior when tested against bacterial strains of Escherichia coli and Bacillus subtilis. Moving ahead, in vitro cytotoxicity work revealed potent cell viability loss appearing in AU565 and HeLa cancer cell lines on exposure to AgNPsMk at increased concentration. Finally, in vivo assessment carried out inside male Wistar rats indicated non toxic effect on examined liver tissues besides biochemical analysis including bilirubin, alkaline phosphtase (ALP) and serum glutamate pyruvate transaminase (SGPT) which found within the normal range when compared with control. The prior research work profoundly apprises the potential of green synthesized AgNPsMk to play a significant role in biomedical applications and formulations.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.26 no.5
• /
• pp.188-192
• /
• 2016

In this work, the SiC powders were synthesized through the carbonized matter from the mixture of silica powder and rice husks. The SiC powders, obtained from the carbothermal reduction reaction of silica and carbonized rice husks, were investigated by XRD patterns, XPS, FE-SEM and FE-TEM. In the XRD patterns, the specimens showed clearly very high strong peak of (111) plane near $35^{\circ}$ as well as weak (220) and (311) peak respectively at approximately $60^{\circ}$ and $72^{\circ}$. Under Ar atmosphere, the power synthesized from the mixture (in case of mixing ratio, 6 : 4) of carbonized rice husks and silica showed mainly cubic SiC crystalline phase showing relatively lower ratio of hexagonal phase without residual carbon in XRD pattern. In the TEM analysis, the specimen, synthesized from carbonized rice husks and silica with mixing ratio of 6 : 4 under Ar atmosphere, showed relatively fine particles under $5{\mu}m$ and a crystalline SiC phase of (100) diffraction pattern.

• Journal of Hydrogen and New Energy
• /
• v.28 no.5
• /
• pp.447-452
• /
• 2017

A $Pd/TiO_2$ catalyst was prepared by a conventional impregnation method, and further characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-Vis spectroscopy. The as-prepared material was employed to accelerate dehydrogenation of potassium formate in the presence of light at different temperatures. The $Pd/TiO_2$ catalyst showed distinct dehydrogenation activities, and particularly, the material exhibited a higher turnover frequency (TOF) of $2,097h^{-1}$ at $80^{\circ}C$ after 10 minutes in the presence of light compared to that (TOF of $1,477h^{-1}$) obtained in the absence of light. Numerous analytical techniques suggest that the increased dehydrogenation activity likely originates from light-excited electron and hole at the photocatalyst, i.e., $TiO_2$, in conjunction with metal-support interaction.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.31 no.1
• /
• pp.13-23
• /
• 2005

This study was performed to investigate mistletoe extract-induced apoptosis in oral squamous cell carcinoma. In vivo study, HN22 cells were xenografted in nude mice. After tumor was experimentally induced, mistletoe extract was directly injected on the tumor mass. The specimens were evaluated using light and transmission electron microscopes. In vitro study, HN22 cells were cultured and exposed to mistletoe extract. The cells were evaluated using transmissin electron microscope. To evaluate apoptotic cells, flow cytometric analysis was done. The results were obtained as follows: 1. Light microscopic view of tumor mass showed necrosis at 2-4 weeks. 2. Transmission electron micrographs of tumor mass showed apoptosis and necrosis. 3. In TEM view of cell lines, necrosis and apoptosis were shown with mistletoe extract at $300{\mu}g/ml$, apoptosis was shown with mistletoe extract at $100{\mu}g/ml$. 4. In flow cytometric analysis, early and late apoptosis was shown when using caspase-3Ab and annexin-V, but no significant change was noted when using mebstain and Apo2.7 Ab. In this study, mistletoe extract induced necrosis and apoptosis in the tumor mass was induced by HN22 cells, early and late apoptosis in vitro study. Mistletoe extract was likely to induce cell death in oral squamous cell carcinoma through apoptosis.