• Applied Biological Chemistry
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• v.19 no.4
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• pp.189-201
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• 1976

In an effort to develop a microbial in secticide, B. thdringiensis var. thuringiensis was cultured in the medium composed of cocoon-cooked water from a filature. The results obtained are summarized as followss : (1) Bacillus thuringiensis is a bacterium producing a ${\delta}-endotoxin$ especially toxic to lepidopterous insects and a thermostable exotoxin harmful to dipterous insects. (2) With a view to utilizing the cocoon-cooked water discarded from the filature, as a nutrient source in the B. thuingiensis culture, it was analyzed to contain large amounts of various minerals and protein (7.5 mg/ml) believed to be extracted from the pupae. (3) A large amount of the ${\delta}-endotoxin$ can be obtained most cheeply by using cocoon-cooked water instead of distilled water in preparing GYS and citrate salts media. (4) The largest amount of a mixture of the vegetative cells, spores, and crystals was obtained by addition of 8 gr/l of glucose to the GYS medium. (5) The growth of the bacterium was far better, when leucine, isoleucine, and valine were added all together to the citrate salts medium to the concentration of $1.25{\times}10^{-3}M$. (6) The best growth was observed by addition of Na-glutamate to the citrate salts medium to the concentration of $2.5{\times}10^{-3}M$. (7) The optimal culture time ranged from 9 to 15 days. (8) The highest mortality was shown in Pieris rapae Linne with a pH of the total body extract of 8.4, whereas Dendrolimus spectabilis Butler and Bombyx mori Linne with lower pH's were less susceptible to the ${\delta}-endotoxin$. (9) The presence of the thermo stable exotoxin was confirmed by the fact that the supernatant of the culture was very toxic to the Drosophila melanogaster tested.

• Journal of Life Science
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• v.26 no.10
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• pp.1113-1120
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• 2016

Two bacterial strains producing extracellular man nanase were isolated from doenjang, a traditionally fermented soybean paste in Korea. The isolates, WL-6 and WL-11, were identified as Bacillus subtiis on the basis of their 16S rRNA gene sequences, morphological, and biochemical properties. Two genes encoding the mannanase of both B. subtilis WL-6 and B. subtilis WL-11 were each cloned into Escherichia coli, and their nucleotide sequences were determined. Both mannanase genes consisted of 1,086 nucleotides, encoding polypeptides of 362 amino acid residues. The deduced amino acid sequences of the two WL-6 and WL-11 mannanases, designated Man6 and Man11, respectively, differed from each other by eight amino acid residues, and they were highly homologous to those of mannanases belonging to the glycosyl hydrolase family 26. The 26 amino acid stretch in the N-terminus of Man6 and Man11 was a predicted signal peptide. Both Man6 and Man11 were localized at the level of 94–95% in an intracellular fraction of recombinant E. coli cells. The enzymes hydrolyzed both locust bean gum and mannooligosaccharides, including mannotriose, mannotetraose, mannopentaose, and mannohexaose, forming mannobiose and mannotriose as predominant products. The optimal reaction conditions were 55°C and pH 6.0 for Man6, and 60°C and pH 5.5 for Man11. Man11 was more stable than Man6 at high temperatures.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.183-184
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• 2013

Two main MBE growth techniques have been used: plasma-assisted MBE (PA-MBE), which utilizes a rf plasma to supply active nitrogen, and ammonia MBE, in which nitrogen is supplied by pyrolysis of NH3 on the sample surface during growth. PA-MBE is typically performed under metal-rich growth conditions, which results in the formation of gallium droplets on the sample surface and a narrow range of conditions for optimal growth. In contrast, high-quality GaN films can be grown by ammonia MBE under an excess nitrogen flux, which in principle should result in improved device uniformity due to the elimination of droplets and wider range of stable growth conditions. A drawback of ammonia MBE, on the other hand, is a serious memory effect of NH3 condensed on the cryo-panels and the vicinity of heaters, which ruins the control of critical growth stages, i.e. the native oxide desorption and the surface reconstruction, and the accurate control of V/III ratio, especially in the initial stage of seed layer growth. In this paper, we demonstrate that the reliable and reproducible growth of GaN on Si (110) substrates is successfully achieved by combining two MBE growth technologies using rf plasma and ammonia and setting a proper growth protocol. Samples were grown in a MBE system equipped with both a nitrogen rf plasma source (SVT) and an ammonia source. The ammonia gas purity was ＞99.9999% and further purified by using a getter filter. The custom-made injector designed to focus the ammonia flux onto the substrate was used for the gas delivery, while aluminum and gallium were provided via conventional effusion cells. The growth sequence to minimize the residual ammonia and subsequent memory effects is the following: (1) Native oxides are desorbed at $750^{\circ}C$ (Fig. (a) for [$1^-10$] and [001] azimuth) (2) 40 nm thick AlN is first grown using nitrogen rf plasma source at $900^{\circ}C$ nder the optimized condition to maintain the layer by layer growth of AlN buffer layer and slightly Al-rich condition. (Fig. (b)) (3) After switching to ammonia source, GaN growth is initiated with different V/III ratio and temperature conditions. A streaky RHEED pattern with an appearance of a weak ($2{\times}2$) reconstruction characteristic of Ga-polarity is observed all along the growth of subsequent GaN layer under optimized conditions. (Fig. (c)) The structural properties as well as dislocation densities as a function of growth conditions have been investigated using symmetrical and asymmetrical x-ray rocking curves. The electrical characteristics as a function of buffer and GaN layer growth conditions as well as the growth sequence will be also discussed. Figure: (a) RHEED pattern after oxide desorption (b) after 40 nm thick AlN growth using nitrogen rf plasma source and (c) after 600 nm thick GaN growth using ammonia source for (upper) [110] and (lower) [001] azimuth.

• Korean Journal of Medicinal Crop Science
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• v.18 no.6
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• pp.389-397
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• 2010

This work was to improve antimicrobial activities of horseradish by encapsulated with edible biopolymers such as lecithin and gelatin since it has been difficult to directly use horseradish extracts into foods and food containers due to its strong and undesirable flavors. It was shown that most of the nanoparticles containing the extracts were well formed in round shape with below 400 nm diameter as well as fairly stable and less odd flavors in various pH ranges by measuring zeta potentials. The encapsulation efficiencies of nanoparticles were estimated as 66.6% and 53.4% for lecithin and gelatin, respectively. Minimal Inhibitory Concentration (MIC) of both nanoparticles against G(+), Listeria monocytogenes and G(-), Salmonella typhimurium were also measured as 79 ppm based on AIT concentrations in the extracts, whose activities were about 65% higher than the case of adding crude extract. It was also found that the nanoparticles efficiently penetrated into the cell membrane and started to destruct the cells after 6 hours cultivation under Transmision Electron Microscopy observation. These results prove that the nano-encapsulation of the horseradish extracts can be employed to directly treat into the foods and food containers for antimicrobial purposes with the aids of aerosolization system, by using small amounts of the extracts and having less flavors due to masking effects of nanoparticles.

• The Korean Journal of Physiology and Pharmacology
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• v.7 no.5
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• pp.267-273
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• 2003

We have investigated the effect on inducing substate(s) of positively charged residues replaced in position 172 of the second transmembrane domain in murine inward rectifier potassium channels, formed by stable or transient transfection of Kir2.1 gene in MEL or CHO cells. Single channel recordings were obtained from either cell-attached patches or inside-out patches excised into solution containing 10 mM EDTA to rule out the effect of $Mg^{2+}$ on the channel gating. The substate(s) could be recorded with all mutants D172H, D172K and D172R. The unitary current-voltage (I-V) relation was not linear with D172H at $pH_i$ 6.3, whereas the unitary I-V relation was linear at $pH_i$ 8.0. The relative occupancy at $S_{LC}$ was increased from 0.018 at $pH_i$ 8.0 to 0.45 at $pH_i$ 5.5. In H-N dimer, that was increased from 0.016 at $pH_i$ 8.0 to 0.23 at $pH_i$ 5.5. The larger the size of the side chain or $pK_a$ with mutants (D172H, D172K and D172R), the more frequent the transitions between the fully open state and substate within an opening. The conductance of the substate also depended upon the pKa or the size of the side chain. The relative occupancy at substate $S_{LC}$ with monomer D172K (0.50) was less than that in K-H dimer (0.83). However, the relative occupancy at substate with D172R (0.79) was similar to that with R-N dimer (0.82). In the contrary to ROMK1, positive charge as well as negative charge in position 172 can induce the substate rather than block the pore in murine Kir2.1. The single channel properties of the mutant, that is, unitary I-V relation, the voltage dependence of the mean open time and relative occupancy of the substates and the increased latency to the first opening, explain the intrinsic gating observed in whole cell recordings.

• Journal of Microbiology and Biotechnology
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• v.23 no.2
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• pp.225-236
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• 2013

Among several bacteria examined, an antibacterial-producing Lactobacillus strain with probiotic characteristics was selected and identified based on 16S rRNA gene sequencing. Subsequent purification and mode of action of the antibacterial compounds on target cells including E. coli were investigated. Maximum production of the antibacterial compound was recorded at 18 h incubation at $30^{\circ}C$. Interestingly, antibacterial activity remained unchanged after heating at $121^{\circ}C$ for 45 min, 24 h storage in temperature range of $70^{\circ}C$ to room temperature, and 15 min exposure to UV light, and it was stable in the pH of range 2-10. The active compounds were inactivated by proteolytic enzymes, indicating their proteinaceous nature, and, therefore, referred to as bacteriocin-like inhibitory substances. Isolation and partial purification of the effective agent was done by performing ammonium sulfate precipitation and gel filtration chromatography. The molecular mass of the GFC-purified active compound (~3 kDa) was determined by Tris-Tricine SDS-PAGE. To predict the mechanisms of action, transmission electron microscopy (TEM) analysis of ultrathin sections of E. coli before and after antibacterial treatment was carried out. TEM analysis of antibacterial compounds-treated E. coli demonstrated that the completely altered bacteria appear much darker compared with the less altered bacteria, suggesting a change in the cytoplasmic composition. There were also some membrane-bound convoluted structures visible within the completely altered bacteria, which could be attributed to the response of the E. coli to the treatment with the antibacterial compound. According to the in vivo experiments oral administration of L. plantarum HKN01 resulted in recovery of infected BALB/c mice with Salmonella enterica ser. Typhimurium.

• Journal of Microbiology and Biotechnology
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• v.27 no.2
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• pp.321-334
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• 2017

Process surveillance within agricultural biogas plants (BGPs) was concurrently studied by high-throughput 16S rRNA gene amplicon sequencing and an optimized quantitative microscopic fingerprinting (QMF) technique. In contrast to 16S rRNA gene amplicons, digitalized microscopy is a rapid and cost-effective method that facilitates enumeration and morphological differentiation of the most significant groups of methanogens regarding their shape and characteristic autofluorescent factor 420. Moreover, the fluorescence signal mirrors cell vitality. In this study, four different BGPs were investigated. The results indicated stable process performance in the mesophilic BGPs and in the thermophilic reactor. Bacterial subcommunity characterization revealed significant differences between the four BGPs. Most remarkably, the genera Defluviitoga and Halocella dominated the thermophilic bacterial subcommunity, whereas members of another taxon, Syntrophaceticus, were found to be abundant in the mesophilic BGP. The domain Archaea was dominated by the genus Methanoculleus in all four BGPs, followed by Methanosaeta in BGP1 and BGP3. In contrast, Methanothermobacter members were highly abundant in the thermophilic BGP4. Furthermore, a high consistency between the sequencing approach and the QMF method was shown, especially for the thermophilic BGP. The differences elucidated that using this biphasic approach for mesophilic BGPs provided novel insights regarding disaggregated single cells of Methanosarcina and Methanosaeta species. Both dominated the archaeal subcommunity and replaced coccoid Methanoculleus members belonging to the same group of Methanomicrobiales that have been frequently observed in similar BGPs. This work demonstrates that combining QMF and 16S rRNA gene amplicon sequencing is a complementary strategy to describe archaeal community structures within biogas processes.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.1
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• pp.55-60
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• 2012

In order to develop electroless-plated Nickel Phosphate (Ni-P) as a contact material for high efficient low-cost silicon solar cells, we evaluated the effect of ambient thermal annealing on the degradation behavior of interfacial adhesion energy between electroless-plated Ni-P and silicon solar cell wafers by applying 4-point bending test method. Measured interfacial adhesion energies decreased from 14.83 to 10.83 J/$m^2$ after annealing at 300 and $600^{\circ}C$, respectively. The X-ray photoelectron spectroscopy analysis suggested that the bonding interface was degraded by environmental residual oxygen, in which the oxidation inhibit the stable formation of Ni silicide phase between electroless-plated Ni-P and silicon interface.

• Journal of Acupuncture Research
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• v.23 no.2
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• pp.73-90
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• 2006

Objectives : The effects of water extract of deer antler herbal-acupunture solution(DHS), prepared from the pilose antler of Cervus korea TEMMINCK var. mantchuricus Swinhoe (Nokyong), a traditional immunosuppressive and immune-activating Korean herbal- acupuncture, on collagen-induced arthritis(CIA:RA model) in mice was studied. Destruction of cartilage and bone are hallmarks of human rheumatoid arthritis, and controlling these erosive processes is the most challenging objective in the treatment of RA. Methods : We investigated the tissue protective effects of deer antler treatment using established murine collagen-induced arthritis(CIA) as a model. Potential synergy of low dosages of anti-inflammatory glucocorticosteroids and deer antler was also evaluated. Results : Treatment of established murine CIA with deer antler herbal-acupunture solution(DHS) $(10-50{\mu}g/day)$ suppressed disease activity and protected against cartilage and bone destruction. Although $10-50{\mu}g/day$ DHS had only a moderate effect on the inflammatory component of the disease activity, it strongly reduced cartilage pathology, as determined by histological examination. Serum cartilage oligomeric matrix protein(COMP) levels were significantly reduced, confirming decreased cartilage involvement. Histological analysis showed that bone destruction was prevented. DHS administration increased serum IL-1Ra levels and reduced anticollagen type II antibody levels. Treatment with low-dose $DHS(1{\mu}g/day)$ was ineffective in suppressing disease score, serum COMP or joint destruction. Synergistic suppression of both arthritis oseverity and COMP levels was noted when low-dose DHS was combined with prednisolone(0.05mg/kg/day), however, which in itself was not effective. Conclusion : DHS was shown to have the inhibiting effects against $IL-1{\alpha}-$ and $IL-1{\beta}-stimulated$ bone resorption. These results indicated that the DAS is not only highly stable and applicable to clinical uses in bone resorption, but also it will be served as a potent anti-inflammatory and anti-arthritic agents for treatment of human RA.

• Journal of the Korean Electrochemical Society
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• v.13 no.2
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• pp.145-152
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• 2010

The gel polymer electrolyte(GPE) were prepared by in-situ thermal cross-linking reaction of homogeneous precursor solution of perfluorinated phosphate-based cross-linker and liquid electrolyte. Ionic conductivities and electrochemical properties of the prepared gel polymer electrolyte with the various contents of liquid electrolytes and perfluorinated organophosphate-based cross-linker were examined. The stable gel polymer electrolyte was obtained up to 97 wt% of the liquid electrolyte. Ionic conductivity and electrochemical properties of the gel polymer electrolytes with the various chain length of perfluorinated ethylene oxide and different content of liquid electrolytes were examined. The maximum ionic conductivity of liquid electrolyte was measured to be $1.02\;{\times}\;10^{-2}\;S/cm$ at $30^{\circ}C$ using the cross-linker($PFT_nGA$). The electrochemical stability of the gel polymer electrolyte was extended to 4.5 V. The electrochemical performances of test cells composed of the resulting gel polymer electrolyte were also studied to evaluate the applicability on the lithium polymer batteries. The test cell carried a discharge capacity of 136.11mAh/g at 0.1C. The discharge capacity was measured to be 91% at 2C rate. The discharge capacity decreased with increase of discharge rate which was due to the polarization. After 500th charge/discharge cycles, the capacity of battery decreased to be 70% of the initial capacity.