• Journal of Powder Materials
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• v.13 no.6 s.59
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• pp.396-400
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• 2006

The Ti-Ni alloy nanopowders were synthesized by a levitational gas condensation (LGC) by using a micron powder feeding system and their particulate properties were investigated by x-ray diffraction (XRD), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) method. The starting Ti and Ni micron powders $150{\mu}m$ were incorporated into the micron powder feeding system. An ingot type of the Ti-Ni ahoy was used as a seed material for the levitation and evaporation reactions. The collected powders were finally passivated by oxidation. The x-ray diffraction experiments have shown that the synthesized powders were completely alloyed with Ti and Ni and comprised of two different cubic and monoclinic crystalline phases. The TEM results showed that the produced powders were very fine and uniform with a spherical particle size of 18 to 32nm. The typical thickness of a passivated oxide layer on the particle surface was about 2 to 3 nm. The specific surface area of the Ti-Ni alloy nanopowders was $60m^2/g$ based on BET method.

• Economic and Environmental Geology
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• v.25 no.3
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• pp.275-282
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• 1992

Mineral chemistry and stable isotope compositions of sericites from the Sangdong mine in the Kimhae area, Kyungsangnamdo, were studied. The Sangdong sericite deposit occurs in rhyolitic tuff of late Cretaceous age and considers to have been fonned by the hydrothennal alteration. The sericites are classified as $2M_1$ polytype and are characterized by less celadonite substitution indicating muscovite-phengite series. Their compositions are very close to that of the ideal muscovite but net layer charge ranges 1.71~1.91 which is less than 2 per formula unit of ideal muscovite. Predominant interlayer cation is K and K/(K+Na) ratio ranges 0.91 and 0.93. ${\delta}^{18}O$ values of sericites and quartz separated from the ore range 7.70~9.07 and 8.20~10.87‰, respectively. The formation temperature of sericite can be estimated as $315{\sim}340^{\circ}C$( based on ${\delta}^{18}O$ value of sericite and ${\delta}D$ value of of Cretaceous meteoric water. Their formation temperature discrepancy between coexisting sericite and quartz indicates that they are in isotopically inequilibrium. Two types of quartz, coarse grained phenocrysts and micrcrystalline aggregates are observed and the former must have been formed during volcanic eruption and remained isotopically unexchanged during hydrothermal alteration period. ${\delta}^{14}S$ values of pyrites range 1.9~4.5‰ which is within a range of volcanogenic sulfur, indicating magmatic source.

• Korean Journal of Weed Science
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• v.17 no.1
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• pp.10-23
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• 1997

This study was carried out to determine distribution and tuberization characteristics of tubers of water chestnut(Eleocharis Kuroguwai Ohwi) which is a dominant weed species and diffult to control during 1993 to 1994. By early planting of E. kuroguwai tubers, more and heavier tubers were developed, but the tubers were tended to distribute at the upper soils. Large proportion of tubers was remained at the upper 0 to 10cm soil layer and a few tubers were formed below 20cm. Tubers developed earlier tended to be at deeper layer, while later developed tubers were at upper layers. Tuber weight was increased from the surface to 20cm soil depths, but that formed below 20cm was almost same. No tillage resulted in more tuber formation which were distributed at upper soil layers when compared to conventional tillage. Cool water irrigation pumped from ground water resulted in less tuberization but smaller tubers when compared to control. Shading with color cellophan films resulted in smaller tuber formation with lower in sprouting percentage. Among the films tested, the most significant effect was obtained with green color.

• Journal of Life Science
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• v.24 no.3
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• pp.242-251
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• 2014

The objective of this study was to isolate a photosensitizer from Pueraria thunbergiana leaves that induces apoptosis in SK-HEP-1 cells. Column chromatography and thin layer chromatography were used to isolate active compounds from extracts of P. thunbergiana leaves. The structures of the isolated compounds were determined by 1D-NMR, 2D-NMR, and FAB-mass spectroscopy. A substance, named M4-3, was purified from the leaves of P. thunbergiana using various chromatography methods, and the absorbance of the substance was measured. The absorbance was highest at 410 nm, suggesting that the M4-3 substance was a different compound from chlorophyll a and b, which absorb at 410, 502, 533, and 607 nm. Further analyses revealed that the M4-3 compound was a $13^2$-hydoxy pheophorbide, a methyl ester with a molecular weight of 662. M4-3 was identified as a derivative compound of pheophorbide, with a structure that magnesium comes away from the porphyrin ring. The results of the analysis of the cytotoxicity of the M4-3 substance against the SK-HEP-1 cells revealed that it inhibited rates of cell growth by 40% and 80% at a concentration of 0.04 ${\mu}M$ and 0.08 ${\mu}M$, respectively. The M4-3 compound was found to be a photosensitizer for cytotoxicity because it was appeared only in light condition as examining activity in different irradiation conditions (light condition and nonlight condition) under the same concentration. Analysis of morphological changes in the cells following cell death induced by exposure to the M4-3 substance reveled representative phenomena of apoptosis (nuclear condensation, vesicle formation, and fragmentation of DNA). The induction of apoptosis was attributed to the compound's photodynamic activity.

• The Korean Journal of Physiology and Pharmacology
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• v.4 no.3
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• pp.185-195
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• 2000

Vascular diseases are significant complications of diabetes mellitus (DM), and the endothelial cells may play a pivotal role in the development of vascular disease in DM. Endothelin-1 (ET-1) released from endothelium is a potent vasoconstrictor peptide and circulating level of ET-1 is increased in a variety of disease states. The purpose of this study was to determine the changes of responsiveness to ET-1 in DM, and we experimented on the changes in the ET-1-induced contraction, levels of nitrite and lipid peroxidation, and ET-1 immunoreactivity in aorta from streptozotocin-induced DM rats. DM was induced by single injection of streptozotocin (55 mg/kg, i.p.). The immunoreactive ET-1 levels in endothelial layer of thoracic aorta were much higher in DM rats than control rats. Nitrite in tissue homogenate was decreased and plasma nitrite was increased in DM rats. Malondialdehyde (MDA) was significantly increased in DM rats and cGMP was not significantly different between control and DM rats. ET-1 produced concentration- dependent contractile responses that are significantly attenuated in DM rats compared to controls. In the presence of selective $ET_A$ receptor antagonist BQ610, the maximum contraction was decreased and the concentration ratios for BQ610 yielded $pA_2$ values of 7.3 (slope, 0.65) in control rats, whereas BQ610 had no antagonistic effect on ET-1-induced contraction in DM rats. However, pretreatment with BQ788, an $ET_B$ receptor antagonist, maximum response was decreased and the dose-response curves for ET-1 were shifted to the right in both groups and $pA_2$ values were 7.9 and 7.7 (slope, 1.05 in control and DM rats), respectively. IRL 1620 and sarafotoxin S6c, $ET_B$ agonists, induced relaxation in control rats but not in DM rats. These results indicate that endothelial cell dysfunction and enhanced immunoreactivity of ET-1 have been found in DM rat and ET-1-induced contraction was attenuated in DM rat. These attenuated responses might be at least in part caused by the alteration of $ET_A$ receptor properties (e.g. desensitization), and partly related with an alteration in intracellular mechanism for contraction to ET-1.

• Korean Journal of Poultry Science
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• v.35 no.4
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• pp.391-398
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• 2009

The objective of the present study was to compare of the effects of four molting methods on performance of laying hens. In total, 120 White Leghorn layers (62 weeks of age) were used. The four molting methods consisted of 10 days of feeding and the first 3 days of water withdrawal (FW1, 2) followed by ad libitum access to a layer diet 1 and 2 from day 11; 28 days of restricted feeding (NFW1); 28 days without withdrawing their feed (NFW2). Egg production of postmolt decreased until $3{\sim}4$ days at FW1 and FW2 treatments and until $16{\sim}18$ days at NFW1 and NFW2. 50% recovery of egg production were 7, 6, 7 and 5 week at FW1, FW2, NFW1, and NFW2 treatments, respectively. At day 14 of postmolt, the weight of livers, hearts, and oviducts decreased at molting treatments (P<0.05). Egg quality was improved on egg weight, eggshell thickness, eggshell break strength, and Haugh unit except egg yolk color (P<0.05).

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.20 no.3
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• pp.119-130
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• 2015

Impacts of Argo temperature assimilation on the analysis fields in the East Sea is investigated by using DAESROM, the East Sea Regional Ocean Model with a 3-dimensional variational assimilation module (Kim et al., 2009). Namely, we produced analysis fields in 2009, in which temperature profiles, sea surface temperature (SST) and sea surface height (SSH) anomaly were assimilated (Exp. AllDa) and carried out additional experiment by withdrawing Argo temperature data (Exp. NoArgo). When comparing both experimental results using assimilated temperature profiles, Root Mean Square Error (RMSE) of the Exp. AllDa is generally lower than the Exp. NoArgo. In particular, the Argo impacts are large in the subsurface layer, showing the RMSE difference of about $0.5^{\circ}C$. Based on the observations of 14 surface drifters, Argo impacts on the current and temperature fields in the surface layer are investigated. In general, surface currents along the drifter positions are improved in the Exp. AllDa, and large RMSE differences (about 2.0~6.0 cm/s) between both experiments are found in drifters which observed longer period in the southern region where Argo density was high. On the other hand, Argo impacts on the SST fields are negligible, and it is considered that SST assimilation with 1-day interval has dominant effects. Similar to the difference of surface current fields between both experiments, SSH fields also reveal significant difference in the southern East Sea, for example the southwestern Yamato Basin where anticyclonic circulation develops. The comparison of SSH fields implies that SSH assimilation does not correct the SSH difference caused by withdrawing Argo data. Thus Argo assimilation has an important role to reproduce meso-scale circulation features in the East Sea.

• Journal of fish pathology
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• v.36 no.2
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• pp.263-275
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• 2023

Chum salmon (Oncorhynchus keta) is a species which returns to Korea for spawning and was produced as seed production at the Fisheries Resources Agency located in Uljin-gun, Gyeongsangbuk-do to preserve the species. However, farmed chum salmon showed symptoms of bacterial infection. Therefore, in this study, bacteria were isolated to identify the causative agent from chum salmon in October 2021. The isolated bacteria were identified based on the sequences of 16S rDNA, rpoD (RNA polymerase sigma factor σ⁷⁰), and vapA (A-layer) genes. Also, salinity-growth curve, biochemical characterization, antibiotic susceptibility test, and pathogenicity analysis were performed in four strains. As a result, four isolated strains were identified as Aeromonas salmonicida subsp. salmonicida. Additionally, the bacterial strains showed a decrease in growth as the salt concentration increased in the medium. All of the isolated strains exhibited γ-hemolysis, and the same biochemical properties. In the antimicrobial susceptibility test, all strains showed an inhibition zone of 40 to 44 mm for oxolinic acid, flumequine, and florfenicol. Pathogenic factors were assessed by RT-PCR at the mRNA level, and found that the four strains expresses the outer membrane ring of T3SS (ascV), inner membrane ring of T3SS (ascC), vapA, enterotoxin (act), and lipase (lip) genes which are well known to significantly contribute to the pathogenicity of A. salmonicida. The results of this study can be used as basic data to prevent A. salmonicida subsp. salmonicida occurring in sea-chum salmon in the future.

• Solar Energy
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• v.20 no.2
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• pp.43-54
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• 2000

We prepared and characterized $Cu(In_{1-x}Ga_x)Se_2$(CIGS) films using a elemental co-evaporation method for absorbing layer of high efficiency thin film solar cells. The CIGS films deposited on a soda-lime glass exhibited low resistivity because of higher carrier concentration. Na was accumulated at the CIGS surface and the 0 and Se were also accumulated at the surface, suggesting that oxidation is a driving force of Na accumulation. The structure of CIGS film was modified or a secondary phase was formed in the Cu-poor CIGS bulk films probably due to the incorporation of Na into Cu vacancy sites. As the Ga/(In+Ga) ratio increased, the diffraction peaks of $Cu(In_{1-x}Ga_x)Se_2$ films were shifted to larger angle and splitted, and the grain size of $Cu_{0.91}(In_{1-x}Ga_x)Se_2$ films became smaller. All $Cu_{0.91}(In_{1-x}Ga_x)Se_2$ films showed the p-type conductivity regardless of the Ga/(In+Ga) ratio. Ag/n-ZnO/i-ZnO/CdS/$Cu_{0.91}(In_{0.7}Ga_{0.3})Se_2$/Mo solar cells were fabricated. The currently best efficiency in this study was 14.48% for $0.18cm^2$ area ($V_{oc}=581.5mV,\;J_{sc}=34.88mA$, F.F=0.714).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.1-6
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• 2019

Organic dye-doped silica nanoparticles are used as a promising nanomaterials for bio-labeling, bio-imaging and bio-sensing. Fluorescent silica nanoparticles(NPs) have been synthesized by the modified $St{\ddot{o}}ber$ method. In this study, dye-free fluorescent silica NPs of various sized were synthesized by Sol-Gel process as the modified $St{\ddot{o}}ber$ method. The functional material of APTES((3-aminopropyl)triethoxysilane) was added as an additive during the Sol-Gel process. The as-synthesized silica NPs were calcined at $400^{\circ}C$ for 2 hours. The surface morphology and particle size of the as-synthesized silica NPs were characterized by field-emission scanning electron microscopy. The fluorescent characteristics of the as-synthesized silica NPs was confirmed by UV lamp irradiation of 365 nm wavelength. The photoluminescence (PL) of the as-synthesized silica NPs with different size was analyzed by fluorometry. As the results, the as-synthesized silica NPs exhibits same blue fluorescent characteristics for different NPs size. Especially, as increased of the silica NPs size, the intensity of PL was decreased. The blue fluorescence of dye-free silica NPs was attributed to linkage of $NH_2$ groups of the APTES layer and oxygen-related defects in the silica matrix skeleton.