• Journal of Microbiology and Biotechnology
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• v.24 no.12
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• pp.1728-1735
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• 2014

Scrub typhus, caused by infection with Orientia tsutsugamushi, is a mite-borne zoonotic disease endemic to the Asian-Pacific region. In Korea, the incidence of this disease has increased with climate changes, and over 10,000 cases of infection were reported in 2013. Although this infection is treatable with antibiotics such as doxycycline and azithromycin, an effective prophylactic vaccine against O. tsutsugamushi would be more desirable for preventing scrub typhus in endemic areas. In this study, we investigated the 56-kDa type-specific antigen (TSA56), which is a major outer membrane protein of O. tsutsugamushi, as a vaccine candidate. Intranasal immunization of recombinant TSA56 (rec56) induced a higher level of TSA56-specific IgG than that induced by intramuscular immunization of tsa56-expressing DNA (p56). Both types of immunization induced a cell-mediated immune response to TSA56, as demonstrated by the splenic cell proliferation assay. Mice immunized with p56, followed by rec56 plus heat-labile enterotoxin B subunit from E. coli, had a stronger protection from a homologous challenge with the O. tsutsugamushi Boryong strain than with other combinations. Our preliminary results suggest that an effective human vaccine for scrub typhus can include either recombinant TSA56 protein or tsa56-expressing DNA, and provide the basis for further studies to optimize vaccine performance using additional antigens or different adjuvants.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2003.11a
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• pp.65-65
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• 2003

The aim of this study was to investigate the effect of resveratrol on the oxidative stress-induced inhibition of gap junctional intercellular communication (GJIC) in HaCaT keratinocyte. Anti-oxidative activity of resveratrol was measured by a,a-diphenyl-b-picrylhydrazyl (DPPH) assay and dichlorodihydrofluorescein diacetate oxidation assay. GJIC of HaCaT keratinocyte was assessed using the scrape loading/dye transfer technique. Western blots and reverse transcription-polymerase chain reaction were also analyzed for Connexin 43 protein and mRNA expression, respectively. Resveratrol scavenged directly the stable DPPH radical over a concentration range of 4 mg/$\mell$ (78.2 $\pm$ 2.7% of control) to 500 mg/$\mell$ (29.9 $\pm$ 4.2% of control) and prevent to increase the intracellular fluorescence induced by oxidative stress significantly. Ultraviolet A irradiation (UVA) and 12-O-tetradecanoylphorbol-13-acetate markedly reduced GJIC, which was restored by resveratrol. There were no significant differences in the level of Connexin 43 protein and mRNA expression among any of the experimental groups. Our data suggests that resveratrol has the protective effect on the oxidative stress-induced inhibition of gap junctional intercellular communication in HaCaT keratinocyte and this protection is likely due to the scavenging of reactive oxygen species.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.337-341
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• 2001

A new method to extract gold from pyrite roster cinder, which combines ultra-fine-grinding with resin-in-pulp, has been studied in this paper. Compared with traditional leaching technology, it can short leaching time, avoid complex filter process, lower sodium cyanide consumption and increase gold recovery by 35%. During leaching, aluminium oxide ball was used as stirred medium, hydrogen peroxide as leaching aid and sodium hexametaphosphate as grinding aid. With the high efficiency and chemistry effect of ultra-fine-grinding, the leaching process was developed and the gold leaching rate may reach 88%. With AM-2 Б resin as abosorber and sulfocarbamide (TU) as eluent, gold was recovered from cyanide pulp by resin-in-pulp. AM-2 Б resin has good adsorbability in cyanide solution(pH=10). It was easy to elude gold from the loaded resin with 0.1㏖/L cholhydric acid and 1㏖/L sulfocabamide. The effect of contact time, temperature and acidity etc. on the gold absorption had been examined with static methods. The results showed that the adsorption and desorption of gold could both reach over 98%. The effects of flow rate of solution on dynamic adsorption and elution of gold had been examined with dynamic methods. Breakthrough curve and elution curve had been drawn in this paper. A mild condition was determined through a number of experiments: leaching time 2 hours, liquid solid ratio 4:1, sodium cyanide 3kg/t, hydrogen peroxide 0.05%, sodium hexametaphosphate 0.05%; adsorption time 30 minutes, temperature 10-3$0^{\circ}C$, resin($m\ell$) solid(g) ratio 1:10, eluent resin ratio 10-20:1, velocity of eluent $1.5m\ell$/min. Under the mild condition, the gold recovery may reach 85%.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.spc1
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• pp.142-150
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• 2006

We examined the effect of predation by observing the changes in macrobenthic communities in a tidal flat at Seonjae, Korea, following the exclusion of large predators such as birds, fishes and crustaceans using protective screens. We conducted two interference experiments in the field from April to November 2004: (1) Experiment 1 was conducted at a mid-tidal flat in the western part of Seonjae-do, Incheon, Korea, (2) Experiment 2 was set up at a low tidal flat in the eastern part of Seonjae-do. predator exclusion showed different effects in the two experiments. Both the number of species and density were reduced by 20% in Experiment 1. Whereas in Experiment 2, they increased by up to 13% and 69%, respectively. In Experiment 1, a high density of brachyuran crabs observed in the treatment may have caused the difference in community composition between the treatment and the control, and this probably resulted from active predation of macrofauna (e.g., small crabs) under protection from megafaunal predators such as birds and fishes. However, in Experiment 2, as typically observed in other predator exclusion experiments, a lower density of benthic predators and the subsequent reduction of over predation probably resulted in a more diverse and abundant benthic community in the treatment. We confirmed that predation was a contributing factor in the formation of the macrobenthic community. We also demonstrated relationships that exist among different trophic groups (large predators, macrobenthic predators and prey) and what effects and responses occur in each component of the tidal flats.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.4
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• pp.924-933
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• 1999

This study investigated the effects of vitamin E supplementation on immune responses and antioxidant status in healthy Korean old and young women. Blood samples were obtained from 15 healthy old women (over 60 years old) and from 15 healthy young women(20 years old) before and 4 weeks after vitamin E( tocopherol acetate) supplementation(400IU/day). Daily nutrient intakes were calculated, and plasma vitamin E concentration, numbers and percentages of white blood cell and their subpopulation, percentages of lymphocytes and subpopulation, NK cell percentages, plasma immunoglobulin A, G, M and C3 concentration, proliferation of PMN with mitogen were measured. Also plasma TBARS concentration and radical scavenger activity of erythrocytes were investigated. Plasma vitamin E concentrations were significantly increased after supplementation in both groups. In elderly women, vitamin E supplementation restored the per centages of neutrophils, lymphocytes, and eosinophils which had been out of normal ranges before supple mentation. And after vitamin E supplementation, helper T cell percentages significantly increased in elderly. Plasma immunoglobulin and complement C3 concentrations were not affected by vitamin E supplementation in both groups. PMN proliferations with mitogen were significantly lower in old women than in young women, and there was no effect of vitamin E supplementation. Vitamin E supplementation significantly decreased plasma TBARS concentrations in old and young women. RSA of erythrocytes was increased in both groups, but the statistical significant was only found in young women group. Therefore, these results suggest that the moderate vitamin E supplementation in old women improves immune responses, especially nonspecific immunity and cell mediated immunity, via protection of oxidant stress.

• Korean Journal of Environmental Agriculture
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• v.34 no.1
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• pp.1-5
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• 2015

BACKGROUND: The stabilities of the two alkaloidal insecticides of S. flavescens including matrine and oxymatrine are important factor to establish expiry date and usage manual for crop protection. However, the environmental stability of the compounds had not been studied with the extract and its commercial biopesticide. METHODS AND RESULTS: The environmental stabilities of the two alkaloids were performed with extract of S. flavescens, and its two commercial biopesticides both in controlled aquatic and soil conditions. The half-lives of the total matrines for the extract and its two commercial biopesticides were estimated over 200 days both under aerobic and anaerobic water condition. Under dry soil condition, the initial decay rates of the matrines were calculated 0.0804-0.1275 ($t_{1/2}$ 5.4-8.6 days), and the half-lives under wet soil condition were calculated 33.0-231 days. Total soil bacteria on the wet soil ranged 6.0-8.0 log CFU/g-soil during the experiments period. CONCLUSION: The aquatic mixture of the extract showed excellent stability both with the extract and its biopesticides, however, the stability of soil mixture were shorter than the aquatic mixture, suggesting that soil metal consider as a catalyst for the degradation of the two alkaloids.

• Journal of the Korean Solar Energy Society
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• v.28 no.2
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• pp.64-69
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• 2008

As the grid-connected photovoltaic power conditioning systems (PVPCS) are installed in many residential areas, these have raised potential problems of network protection on electrical power system. One of the numerous problems is an Islanding phenomenon. There has been an argument that it may be a non-issue in practice because the probability of islanding is extremely low. However, there are three counter-arguments: First, the low probability of islanding is based on the assumption of 100% power matching between the PVPCS and the islanded local loads. In fact, an islanding can be easily formed even without 100% power matching (the power mismatch could be up to 30% if only traditional protections are used, e.g. under/over voltage/frequency). The 30% power-mismatch condition will drastically increase the islanding probability. Second, even with a larger power mismatch, the time for voltage or frequency to deviate sufficiently to cause a trip, plus the time required to execute a trip (particularly if conventional switchgear is required to operate), can easily be greater than the typical re-close time on the distribution circuit. Third, the low-probability argument is based on the study of PVPCS. Especially, if the output power of PVPCS equals to power consumption of local loads, it is very difficult for the PVPCS to sustain the voltage and frequency in an islanding. Unintentional islanding of PVPCS may result in power-quality issues, interference to grid-protection devices, equipment damage, and even personnel safety hazards. Therefore the verification of anti-islanding performance is strongly needed. In this paper, improved RPV method is proposed through considering power quality and anti-islanding capacity of grid-connected single-phase PVPCS in IEEE Std 1547 ("Standard for Interconnecting Distributed Resources to Electric Power Systems"). And the simulation results are verified.

• The Korean Journal of Pesticide Science
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• v.4 no.3
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• pp.40-46
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• 2000

To select the effective fungicides for the control of leaf spot disease of jujube tree (Zizyphus jujuba) caused by Phoma sp., inhibitory effects of 26 fungicides for mycelial growth were investigated at $250{\mu}g\;a.i./m{\ell}$. In the test, eight fungicides were selected and minimum inhibitory concentration (MIC) for mycelial growth and an inhibitory effect for spore germination were investigated. Among the fungicides, myclobutanil, hexaconazole, and triflumizole were excluded in control effect tests because of their relatively high MICs. MICs were ranged $10-50{\mu}g\;a.i./m{\ell}$ for benomyl, carbendazim + kasugamycin (CK), and thiophanate-methyl. triflumizole (TT), and $50-250{\mu}g\;a.i./m{\ell}$ for iprodione + propineb (IT) and iminoctadine-triacelate (IT). However, benomyl and IP showed very low inhibitory effect on conidial germination. When the fungicides were sprayed on the seedlings before the leaves were inoculated with conidial suspension of Phoma sp., the protective values of CK and TT were around 70% at 1,000 ppm and around 90% at 2,000 ppm. The protective values were around 70% at 2,000 ppm (benomyl), 4,000 ppm (IP), and 8,000 ppm (IT). When the fungicides were sprayed after inoculation, benomyl showed the highest curative values of over 90% at 1,000 ppm and the values of CK and TT ranged $70{\sim}80%$ at 1,000 ppm. However, IP and IT had little or no effect on therapy of the disease. IT caused necrotic phytotoxicity on the leaves of jujube seedlings. As results, the best fungicides for the protection of jujube trees from leaf spot disease were CK (2,000 ppm) and TT (2,000 ppm) and for the remedy of the tree, benomyl (1,000 ppm) was the best. Therefore, alternate application of benomyl and CK or TT will be effective in the disease control.

• Korean Journal of Food Science and Technology
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• v.38 no.3
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• pp.452-455
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• 2006

The in vitro cytoprotective and anti-oxidative effects of ursodeoxycholic acid, a major active compound from bear's gall were investigated in mouse brain microglia. In the present study, we wished to scrutinize the potential role of UDCA as an anti-neurodegenerative agent in neurodegenerative disease such as Alzheimer's disease. This concept was supported by the multiple preliminary studies in which UDCA has an anti-inflammatory effect in microglial cells. In the study, we found that $7.5\;{\mu}g/mL$ UDCA was effective in the protection of cells from $H_2O_2$ damage, a reactive oxygen, and the resuIt was coincided with the anti-apoptotic effect in DAPI staining. Moreover, the metal-catalyzed oxidation study showed that UDCA has antioxidant effect as much as ascorbic acid at $50{\sim}100\;{\mu}g/mL$. In conclusion, these study results suggested that neuro-degenerative diseases such as Alzheimer's disease probably caused by over-expressed beta amyloid peptide in elderly people can be controled by UDCA through an anti-inflammatory, anti-oxidative and anti-apoptotic effect. The evidences showed in the study may be references for more in-depth in vivo and clinical studies for a candidate of anti-neurodegenerative therapy in the near future.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.6
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• pp.786-794
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• 2022

Green ammonia is a promising renewable energy carrier. Green ammonia can be used in various energy conversion devices (e.g., engine, fuel cell, etc.). Ammonia has to be fed with hydrogen for start-up and failure protection of some energy conversion devices. Ammonia can be converted into hydrogen by decomposition and partial oxidation. Especially, partial oxidation has the advantages of fast start-up, thermally self-sustaining operation and compact size. In this paper, thermodynamics, start-up and operation characteristics of ammonia partial oxidation were investigated. O₂/NH₃ ratio, ammonia flow rate and catalyst volume were varied as operation parameters. In thermodynamic analysis, ammonia conversion was maximized in the O₂/NH₃ range from 0.10 to 0.15. Ammonia partial oxidation reactor was successfully started using 12 V glow plug. At 0.13 of O₂/HN₃ ratio and 10 LPM of ammonia flow rate, ammonia partial oxidation reactor showed 90% of ammonia conversion over commercial Ru catalyst. In addition, Increasing O₂/NH₃ ratio from 0.10 to 0.13 was more effective for high ammonia conversion than increasing catalyst volume at 0.10 of O₂/NH₃.