• The Plant Pathology Journal
• /
• v.26 no.4
• /
• pp.328-339
• /
• 2010

A tobamovirus, Ribgrass mosaic virus (RMV), was identified newly from chinese cabbage (Brassica campestris L. pekinensis) in Korea. Virus disease incidence of RMV on chinese cabbage was 37.9% in alpine area on August in 1993. RMV induced the symptoms of necrotic ring spots, necrotic streak on midrib and malformation. RMV, Ca1 and Ca3 isolate, could infect 35 species out of 45 plants including Chenopodium amaranticolor. Physical properties of RMV Ca1 isolate were very stable as 10.8 over for dilution end point, $95^{\circ}C$ for temperature inactivation point and 18 weeks for longevity in vitro. RMV had the soil transmission rate of 75.0% for the chinese cabbages, 'Chunhawang' and 'Seoul' cultivars. The purified virions of RMV had the typical ultraviolet absorption spectrum of maximum at 260 nm and minimum at 247 nm. RMV of Ca1 isolate was related serologically with antisera of Tobacco mosaic virus (TMV)-Cym, TMV-O and Pepper mottle virus, but not related with antiserum of Odontoglossum ring spot virus. coat protein gene of RMV-Ca1, sized 473 nucleotides, encoded 158 amino acid residues. Nucleotide identity of RMV-Ca1 CP gene was 96.4% with RMV-Shanghai (GenBank accession No. of AF185272) from China and 96.0% with RMV-Impatiens (GenBank accession No. of AM040974) from Germany. Identity of amino acids between RMV-Ca1 and the two RMV isolates was 96.8%. Specific three primers were selected for rapid and easy genetic detection of RMV using Virion Captured (VC)/RT-PCR method.

• Korean Journal of Materials Research
• /
• v.18 no.2
• /
• pp.92-97
• /
• 2008

In spray pyrolysis, the effects of the preparation temperature, flow rate of the carrier gas and concentration of the spray solution on characteristics such as the morphology, size, and emission intensity of $Ca_8Mg(SiO_4)_4Cl_2:Eu^{2+}$ phosphor powders under long-wavelength ultraviolet light were investigated. The phosphor powders obtained post-treatment had a range of micron sizes with regular morphologies. However, the composition, crystal structure and photoluminescence intensity of the phosphor powders were affected by the preparation conditions of the precursor powders. The $Ca_8Mg(SiO_4)_4Cl_2:Eu^{2+}$ phosphor powders prepared at temperatures that were lower and higher than $700^{\circ}C$ had low photoluminescence intensities due to deficiencies related to the of Cl component. The phosphor powders with the deficient Cl component had impurity peaks of $Ca_2SiO_4$. The optimum flow rates of the carrier gas in the preparation of the $Ca_8Mg(SiO_4)_4Cl_2:Eu^{2+}$ phosphor powders with high photoluminescence intensities and regular morphologies were between 40 and 60 l/minute. Phosphor powders prepared from a spray solution above 0.5 M had regular morphologies and high photoluminescence intensities.

• Journal of Food Hygiene and Safety
• /
• v.17 no.3
• /
• pp.117-123
• /
• 2002

The five main green tea catechin components such as (+)-catechin, (-)-epicatechin, (-)-epigallocatechin, (-)-epicatechin gallate, and (-)-epigallocatechin gallate were analyzed quantitatively from commercial green tea by HPLC. Amounts of catechins decreased in the following order : (+)-catechin > (-)-epigallocatechin gallate >(-)-epigallocatechin >(-)-epicatechin >(-)-epicatechin gallate. In this study, the stability of the following green tea catechins to pH in the range from 3 to 11 was studied using of ultraviolet spectroscopy : (+)-catechin, (-)-epicatechin, (-)-epicatechin gallate, and (-)-epigallocatechin gallate. This study demonstrated that green tea catechins were not stable at high pH and that the pH-, and time-dependent spectral alternatives were not reversible In conclusion, low pH is important to maintain the efficient utilization of green tea catechins.

• Journal of the Korean Applied Science and Technology
• /
• v.8 no.2
• /
• pp.161-167
• /
• 1991

The kinetics of hydrolysis of cinnamenylisophorone derivatives (${rho}-H,\;{rho}-Br,\;P-Cl,\;{rho}-OCH_3$) was investigated using ultraviolet spectrophotometry in 20%(v/v) dicxane-$H_2O$ at 25$^{\circ}C$. A rate equation which can be applied over wide pH range (pH $1.0{\sim}13.0$) was obtained. In order to investigate the substituent effects on cinnarnenylisophorone derivatives, Hammett constant was plotted. As the result, the rate of hydrolysis of cinnamenylisophorone derivatives was facilitated by electron donating group. Final products of the hydrolysis were benzaldehyde and isophorone, From the measurement of reaction rate constant according to pH changes, substituent effect, and final products, it was found that the hydrolysis of cinnarnenylisophorone derivatives was initiated by the neutral $H_2O$ molecule which does not dissociated at below pH 9.0, and in the range of pH $9.0{\sim}11.0$ this reaction occurs by $H_2O$ or hydroxide ion competitively, but proceeded by the hydroxide ion above pH 11.0. On the basis of this kinetic study, the reaction mechanism of the hydrolysis of cinnamenylisophorone derivatives was proposed.

• Archives of Pharmacal Research
• /
• v.26 no.9
• /
• pp.739-746
• /
• 2003

Ultraviolet B (UVB) is known to induce apoptosis in human melanocytes. Here we show the cytoprotective effect of sphingosine-1-phosphate (S1P) against UVB-induced apoptosis. We also show that UVB-induced apoptosis of melanocytes is mediated by caspase-3 activation and poly(ADP-ribose) polymerase (PARP) cleavage, and that S1P prevents apoptosis by inhibiting this apoptotic pathway. We further investigated three major mitogen-activated protein (MAP) kinases after UVB irradiation. UVB gradually activated c-Jun N-terminal kinase (JNK) and p38 MAP kinase, while extracellular signal-regulated protein kinase (ERK) was inactivated transiently. Blocking of the p38 MAP kinase pathway using SB203580 promoted cell survival and inhibited the activation of caspase-3 and PARP cleavage. These results suggest that p38 MAP kinase activation may play an important role in the UVB-induced apoptosis of human melanocytes. To explain this cytoprotective effect, we next examined whether S1P could inhibit UVB-induced JNK and p38 MAP kinase activation. However, S1P was not found to have any influence on UVB-induced JNK or p38 MAP kinase activation. In contrast, S1P clearly stimulated the phosphorylation of ERK, and the specific inhibition of the ERK pathway using PD98059 abolished the cytoprotective effect of S1P. Based on these results, we conclude that the activation of p38 MAP kinase plays an important role in UVB-induced apoptosis, and that S1P may show its cytoprotective effect through ERK activation in human melanocytes.

• Korean Journal of Pharmacognosy
• /
• v.50 no.2
• /
• pp.148-153
• /
• 2019

The lignan compound of Schisandra chinensis Baill. (Schizandraceae) has been reported to have a variety of biological activities such as liver protection, neuroprotection, anti-oxidant and anti-diabetes. In this study, we investigated a quantitative analytical method for schisandrin, gomisin A and gomisin $M_2$ isolated from S. chinensis by high-performance liquid chromatography-ultraviolet spectroscopy (HPLC-UV). The isolated compounds were identified by the analysis of 1H- and 13C-NMR spectroscopic data. The results showed that calibration curves of three compounds indicated great linearity with a correlation coefficient ($R^2$) of schisandrin 0.9983, gomisin A 0.9982 and gomisin $M_2$ 0.9986. The limits of detection (LOD) of schisandrin, gomisin A and gomisin $M_2$ were 0.14, 0.07 and $0.05{\mu}g/ml$ and the limits of quantification (LOQ) were 0.42, 0.22 and $0.14{\mu}g/ml$. Intra-day and inter-day precisions of schisandrin were 0.40~1.44%, 0.07~1.02% gomsin A were 0.22~0.52%, 0.10~0.63%, gomisin $M_2$ were 0.40~0.99%, 0.81~2.88%. In result, contents of schisandrin, gomisin A and gomisin $M_2$ in ethanol extract of S. chinensis were $25.95{\pm}0.15$, $2.51{\pm}0.02$ and $2.17{\pm}0.07mg/g$.

• Korean Journal of Materials Research
• /
• v.29 no.7
• /
• pp.456-462
• /
• 2019

ZnO thin-films are grown on a p-Si(111) substrate by RF sputtering. The effects of growth temperature and $O_2$ mixture ratio on the ZnO films are investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and room-temperature photoluminescence (PL) measurements. All the grown ZnO thin films show a strong preferred orientation along the c-axis, with an intense ultraviolet emission centered at 377 nm. However, when $O_2$ is mixed with the sputtering gas, the half width at half maximum (FWHM) of the XRD peak increases and the deep-level defect-related emission PL band becomes pronounced. In addition, an n-ZnO/p-Si heterojunction diode is fabricated by photolithographic processes and characterized using its current-voltage (I-V) characteristic curve and photoresponsivity. The fabricated n-ZnO/p-Si heterojunction diode exhibits typical rectifying I-V characteristics, with turn-on voltage of about 1.1 V and ideality factor of 1.7. The ratio of current density at ${\pm}3V$ of the reverse and forward bias voltage is about $5.8{\times}10^3$, which demonstrates the switching performance of the fabricated diode. The photoresponse of the diode under illumination of chopped with 40 Hz white light source shows fast response time and recovery time of 0.5 msec and 0.4 msec, respectively.

• Journal of Korean Society on Water Environment
• /
• v.27 no.5
• /
• pp.625-633
• /
• 2011

A long-term water quality monitoring in the Han River Basin reveals a consistent increasing trend for the concentration of refractory organic matter (R-OM) in major monitoring sites of the watershed. Because the determination of R-OM concentrations typically requires a long time of microbial incubation, it is essential to present the estimation indices for R-OM for an efficient watershed management. In this study, a number of surface water samples were classified into three groups, each of which were collected from Lake Paldang, rivers at rain and non-rain events, respectively. The corresponding R-OM concentrations were correlated with biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total organic carbon (TOC) concentrations as well as ultraviolet and fluorescence intensities of the filtered samples. Among the traditional organic matter parameters, TOC exhibited the highest correlation coefficient with the R-OM concentrations regardless of the types of the sample groups. The equations for conversing TOC into R-OM concentrations were finally suggested as $0.43{\times}TOC+1.12$, $0.44{\times}TOC+0.61$, $0.24{\times}TOC+1.28$ for river samples at rain and non-rain events, and lake samples, respectively. TOC-BOD(C), the values of the TOC concentrations subtracted by carbon-converted BOD concentrations, was a good index for estimating the absolute concentrations of R-OM. UV absorbance at 254 nm was well correlated with R-OM concentrations of river samples while fluorescence intensities at 350 nm showed an excellent relationship with R-OM concentration of the lake samples. Our results suggests that simple spectroscopic parameters could be applied for in-situ monitoring tool techniques in watersheds.

• Current Photovoltaic Research
• /
• v.8 no.4
• /
• pp.124-128
• /
• 2020

Output power of photovoltaic (PV) modules installed outdoors decreases every year due to environmental conditions such as temperature, humidity, and ultraviolet irradiations. In order to promote the installation of PV modules, the reliability must be guaranteed. One of the important factors affecting reliability is intermetallic compounds (IMC) layer formed in ribbon solder joint. For this reason, various studies on soldering properties between the ribbon and cell have been performed to solve the reliability deterioration caused by excessive growth of the IMC layer. However, the IMC layer of the PV module interconnected by multi-wires has been studied less than using the ribbon. It is necessary to study soldering characteristics of the multi-wire module for improvement of its reliability. In this study, we analyzed the growth of IMC layer of the PV module with multi-wire and the degradation of output power through damp-heat test. The fabricated modules were exposed to damp-heat conditions (85 ºC and 85 % relative humidity) for 1000 hours and the output powers of the modules before and after the damp-heat test were measured. Then, the process of dissolving ethylene vinyl acetate (EVA) as an encapsulant of the modules was performed to observe the IMC layer. The growth of IMC layer was evaluated using OM and FE-SEM for cross-sectional analysis and EDS for elemental mapping. Based on these results, we investigated the correlation between the IMC layer and output power of modules.

• Advances in nano research
• /
• v.10 no.2
• /
• pp.191-210
• /
• 2021

To compare the antifungal effect of two nanomaterials (NMs), nanoparticles of zinc oxide were synthesized by a chemical route and zinc oxide-based nanobiohybrids were obtained using green synthesis in an extract of garlic (Allium sativum). The techniques of X-Ray Diffraction (XRD), Infrared (IR) and Ultraviolet Visible (UV-Vis) absorption spectroscopies and Scanning (SEM) and Transmission Electron Microscopies (TEM) were used to determine the characteristics of the nanomaterials synthesized. The results showed that the samples obtained were of nanometric size (< 100 nm). To compare their antifungal capacity, their effect on Cercospora sp. was evaluated. Test results showed that both nanomaterials had an antifungal capacity. The nanobiohybrids (green route) gave an inhibition of fungal growth of ~72.4% while with the ZnO-NPs (chemical route), inhibition was ~87.1%. Microstructural studies using High Resolution Optical Microscopy (HROM) and ultra-structural analysis using TEM carried out on the treated strains demonstrated the effect of the nanofungicides on the vegetative and reproductive structures, as well as on their cell wall. To account for the antifungal effect presented by ZnO-NPs and ZnO nanobiohybrids on the fungi tested, effects reported in the literature related to the action of nanomaterials on biological entities were considered. Specifically, we discuss the electrical interaction of the ZnO-NPs with the cell membrane and the biomolecules (proteins) present in the fungi, taking into account the n-type nature of the ZnO semiconductor and the electrical behavior of the fungal cell membrane and that of the proteins that make up the protein crown.