• Journal of Powder Materials
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• v.17 no.3
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• pp.203-208
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• 2010

A new High Frequency Induction Heating (HFIH) process has been developed to fabricate dense $Al_2O_3$ reinforced with Fe-Ni magnetic metal dispersion particles. The process is based on the reduction of metal oxide particles immediately prior to sintering. The synthesized $Al_2O_3$/Fe-Ni nanocomposite powders were formed directly from the selective reduction of metal oxide powders, such as NiO and $Fe_2O_3$. Dense $Al_2O_3$/Fe-Ni nanocomposite was fabricated using the HFIH method with an extremely high heating rate of $2000^{\circ}C/min$. Phase identification and microstructure of nanocomposite powders and sintered specimens were determined by X-ray diffraction and SEM and TEM, respectively. Vickers hardness experiment were performed to investigate the mechanical properties of the $Al_2O_3$/Fe-Ni nanocomposite.

• Journal of Microbiology and Biotechnology
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• v.26 no.2
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• pp.394-401
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• 2016

Recently, the clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9 (CRISPR/Cas9) system, a genome editing technology, was shown to be versatile in treating several antibiotic-resistant bacteria. In the present study, we applied the CRISPR/Cas9 technology to kill extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli. ESBL bacteria are mostly multidrug resistant (MDR), and have plasmid-mediated antibiotic resistance genes that can be easily transferred to other members of the bacterial community by horizontal gene transfer. To restore sensitivity to antibiotics in these bacteria, we searched for a CRISPR/Cas9 target sequence that was conserved among >1,000 ESBL mutants. There was only one target sequence for each TEM- and SHV-type ESBL, with each of these sequences found in ~200 ESBL strains of each type. Furthermore, we showed that these target sequences can be exploited to re-sensitize MDR cells in which resistance is mediated by genes that are not the target of the CRISPR/Cas9 system, but by genes that are present on the same plasmid as target genes. We believe our Re-Sensitization to Antibiotics from Resistance (ReSAFR) technology, which enhances the practical value of the CRISPR/Cas9 system, will be an effective method of treatment against plasmid-carrying MDR bacteria.

• Journal of Microbiology and Biotechnology
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• v.22 no.6
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• pp.872-881
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• 2012

The inhibitory effect of the Klebsiella pneumoniae ATCC 13883 strain caused by the hexane extract of Halimeda discoidea (Nor Afifah et al., 2010) was further evaluated by means of the microscopy view and its growth curves. The morphological changes of the K. pneumoniae ATCC 13883 cells were observed under the scanning electron microscope (SEM) and transmission electron microscope (TEM) after they were treated at minimum inhibitory concentration (MIC; 0.50 mg/ml) (Nor Afifah et al., 2010) for 12, 24, and 36 h. The results showed the severity of the morphological deteriorations experienced by the treated cells. The killing curve assay was performed for 48 h at three different extract concentrations (1/2 MIC, MIC, and 2 MIC). An increase in the extract concentration of up to 2 MIC value did significantly reduce the number of cells by approximately 1.9 $log_{10}$, as compared with the control. Identification of the potential compounds of the extract responsible for the antibacterial activity was carried out through the gas chromatography-mass spectrum (GC-MS) analysis of the active subfraction, and the compound E-15-heptadecenal was identified and suggested as the most potential antibacterial compound of this extract. The subsequent cellular degenerations showed by the data might well explain the inhibitory mechanisms of the suggested antibacterial compound. All of these inhibitory effects have further proven the presence of an antibacterial compound within H. discoidea that can inhibit the growth of K. pneumoniae ATCC 13883.

• Journal of Microbiology and Biotechnology
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• v.24 no.7
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• pp.879-887
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• 2014

Bacteria that mediate the anaerobic oxidation of ammonium (anammox) have been detected in natural ecosystems, as well as various wastewater treatment systems. In this study, sludge from a particular landfill leachate anaerobic treatment system was selected as the incubation seed for anammox microorganism enrichment owing to its possible anammox activity. Transmission electron microscopy observation, denaturing gradient gel electrophoresis analysis, and cloning/sequencing techniques were applied to identify the diversity of anammox microorganisms throughout the incubation. During the early stage of operation, the diversity of anammox microorganisms was similar to the original complex microbes in the seed sludge. However, as incubation time increased, the anammox microorganism diversity within the system that was originally dominated by Candidatus (Ca.) Brocadia sp. was replaced by Ca. Anammoxoglobus propionicus. The domination of Ca. Anammoxoglobus propionicus produced a stable removal of ammonia (70 mg-N/l) and nitrite (90 mg-N/l), and the total nitrogen removal efficiency was maintained at nearly 95%. The fluorescence in situ hybridization results showed that Ca. Anammoxoglobus propionicus was successfully enriched from $1.8{\pm}0.6%$ initially to $65{\pm}5%$ after 481 days of operation. Therefore, the present results demonstrated the feasibility of enriching Ca. Anammoxoglobus propionicus from leachate sludge, even though the original cell count was extremely low. Application of this seldom found anammox organism could offer an alternative to current ammonia-nitrogen treatment.

• Journal of Surface Science and Engineering
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• v.47 no.2
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• pp.68-74
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• 2014

The seed step-coverage enhancement process (SSEP) using Pd/Cu/PVP colloids was investigated for the filling of through silicon via (TSV) without void. TEM analysis showed that the Pd/Cu nano-particles were well dispersed in aqueous solution with the average diameter of 6.18 nm. This Pd/Cu nano-particles were uniformly deposited on the substrate of Si/$SiO_2$/Ti wafer using electrophoresis with the high frequency Alternating Current (AC). After electroless Cu deposition on the substrate treated with Pd/Cu/PVP colloids, the adhesive property between deposited Cu layer and substrate was evaluated. The Cu deposit obtained by SSEP with Pd/Cu/PVP colloids showed superior adhesion property to that on Pd ion catalyst-treated substrate. Finally, by implementing the SSEP using Pd/Cu/PVP colloids, we achieved 700% improvement of step coverage of Cu seed layer compared to PVD process, resulting in void-free filling in high aspect ratio TSV.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.2
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• pp.333-337
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• 2002

To develope food preservative, antimicrobial activities of Pinus densiflora (PD) ethanol extract against Listeria monocytogenes Scott A. Listeria monocytogenes Brie I and Listeria monocytogenes ATCC 19111 were investigated. The ethanol extracts of PD showed strong antimicrobial activities on Listeria monocytogenes. The crude ethanol extracts of PD were further fractionated by ether, ethyl acetate and butanol. The ether fraction from ethanol extract showed the strongest antimicrobial effects on Listeria monocytogenes in tryptic soy broth containing 40 mg/mL ether fractions compared with other fractions. The effect of ethanol extract of pinus densiflora against Listeria monocytogenes culture for growth stage in tryptic soy broth at 35$^{\circ}C$ showed the strongest antimicrobial activites for lag phase. The morphological changes of the cells were observed with transmission electron microscope (TEM) and scanning electron microscope (SEM) and the cells were injured by treatment of 40 mg/mL ethanol extract of Pinus densiflora.

• Korean Journal of Ichthyology
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• v.12 no.2
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• pp.111-117
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• 2000

There were observed the histomorphological alterations such as chloride cell hyperplasia, branchial lamellar epithelial separation, the increased cellular turnover of chloride cells, glomerular shrinkage and blood congestion in rainbow trout (Oncorhynchus mykiss) during the seawater adaptation. The ultrastructure by scanning electron microscope (SEM) indicated that the gill secondary lamella of rainbow trout exposed to seawater, were characterized by rough convoluted surfaces during the adaptation. There were observed a large number of mitochondria with the elongate and well-developed cristae in chloride cells exposed to seawater by transmission electron microscope (TEM). The presence of two mitochondria- rich cell types is discussed with regard to their possible role in the hypoosmoregulatory changes which occur during seawater-adaptation. Glomerulus shrinkage and blood congestion were occurred higher in nephrons of seawater-adapted fish than those living in freshwater. Our findings demonstrated that rainbow trout tolerated moderately saline environment and the increased body weight living in seawater was relatively higher than that living in freshwater in spite of histopathological changes.

• Korean journal of food and cookery science
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• v.11 no.2
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• pp.153-157
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• 1995

The effect of low concentrations of ethanol(3∼7%, v/v) in culture broth as an antibacteriaB agent against Vibrio parahaemolyticus was tested at -20, 5, 35, 45 and 5%. Increasing concentrations of ethanol progressively inhibited initial growth of t: parahaemelyticus at 35$^{\circ}C$. Growth occured at 5% ethanol, but only after a prolonged lag period. At 7% ethanol, the number of viable cells of V parahae-molyticus declined during incubation. Culture broth containiilg 3∼7% ethanol was inoculated with 106∼107'cells/uu of V Parahaemolyticus and incubated at low temperatures(5$^{\circ}C$, -20$^{\circ}C$) and high tem-peratures(45$^{\circ}C$, 50$^{\circ}C$). In the presence of 5 or 7ft of ethanol, the viability in the cells incubated at high temperatures decreased rapidly. Rate of death increased with increasing concentration of etha-nol.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.25 no.2
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• pp.483-499
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• 1995

Mandibular first molars of the rats were undertaken to observe the radiosensitivity of amelogenesis. Twenty four Sprague-Dawley rats received 396cGy radiation with the MK Cell irradiator using Cs-137, and twenty four rats served as control. They were devided into two groups; Group 1 which received radiation at the 14th day after gestation and group 2 which received radiation at the 19th day after gestation. Light Microscopy and Transmitted Electron Microscopy investigation was undertaken in the group 1 at the 15th, 18th, 20th, 22nd(2 days after birth), and 25th day(5 days after birth) after gestation, and in the group 2 at the 21th(birth day), 22nd(2 days after birth), and 25th(5 days after birth) day after gestation. The following histopathologic findings were obtained. 1. Compared with control group, experimental group showed a delayed formation of enamel and dentin due to slow rate of differentiation of undifferentiated mesenchymal cells. 2. In the experimental groups, the arrangement of the inner enamel epithelium was irregular and there were many vacuoles in the cytoplasm. There were dilated rER and mitochondria, increase of the intercellular space, and loss of the cellular polarity. 3. In the group 1, early enamel without Tomes' process, and early organic matrix was observed at the 25th day after gestation. 4. In the group 2, histopathologic changes were similar to those of the group 1, but the degree of changes was more severe than that of the group 1.

• Journal of the Korean Ceramic Society
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• v.44 no.6 s.301
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• pp.325-330
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• 2007

High porous AlO(OH) gel is used in precursor of ceramic material, coating material and porous catalyst. For use of these, not only physiochemical control for particle morphology, pore characteristic and peptization but also studies of synthetic method for preparation of high porous AlO(OH) gel were required. In this study, high porous AlO(OH) gel was prepared through the aging and filtration process of aluminum hydroxides gel precipitated by the hydrolysis reaction of $Na_2CO_3$ solution and $Al_2(SO_4)_3$ and $Na_2SO_4$ mixed solution. In this process, optimum synthetic condition of AlO(OH) gel having excellent pore volume as studying the effect of hydrolysis pH on gel precipitates has been studied. Hydrolysis pH brought about numerous changes on crystal morphology, surface area, pore volume and pore size. Physiochemical properties of gel were investigated as using XRD, TEM, TG/DTA, FT-IR and $N_2$ BET method.