• 한국표면공학회지
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• 제54권3호
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• pp.144-151
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• 2021

In the present work, planar-type ZnO powder of [0001] plane with a high aspect ratio range of 20:1 to 50:1 was synthesized. Ag or CuO could be coated on the planar-type ZnO powder by wet methods such as centrifugation or ball milling. During the coating, the average size of the powder was slightly increased while maintaining the shape and XRD pattern of ZnO. When Ag or CuO was coated, the absolute value of the zeta potential, as well as the concentration of oxygen vacancy, was increased. Ag or CuO coated planar-type ZnO power exhibited excellent antibacterial performance, which seems to be related to their high electrostatic attraction force. They could be made into a masterbatch by mixing with ABS resin, and their applicability to antibacterial substances was confirmed by manufacturing the caps of a keyboard.

• Journal of Microbiology and Biotechnology
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• 제32권12호
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• pp.1589-1598
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• 2022

Microfibrillated cellulose (MFC) is a valuable material with wide industrial applications, particularly for the food and cosmetics industries, owing to its excellent physiochemical properties. Here, we prepared high-solid microfibrillated cellulose (HMFC) from the centrifugation of Gelidium amansiiderived MFC right after fibrillation. Dispersion properties, morphology, and structural changes were monitored during processing. HMFC has a five-fold higher solid concentration than MFC without significant changes to dispersion properties. SEM images and FTIR spectra of HMFC revealed a stable surface and structure against centrifugal forces. HMFC exhibited 2,2'-azino-bis (3-ethylbenzothiazoline6-sulfonic acid) (ABTS) radical scavenging activity, although it could not scavenge 2,2-diphenyl-1- picrylhydrazyl (DPPH). Moreover, HMFC inhibited the generation of LPS-induced excessive nitrite and radial oxygen species in murine macrophage RAW264.7 cells. Additionally, HMFC suppressed LPS-induced Keap-1 expression in the cytosol but did not alter iNOS expression. HMFC also attenuated the UVB-induced phosphorylation of p38, c-Jun N-terminal kinase (JNK) 1/2, and extracellular-signal-regulated kinase (ERK) 1/2, as well as the phosphorylation of c-Jun in the immortalized human skin keratinocyte HaCaT cells. Therefore, the application of centrifugation is suitable for producing high-solid MFC as a candidate material for anti-inflammatory and antioxidative marine cosmeceuticals.

• ALGAE
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• 제39권2호
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• pp.109-127
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• 2024

High production and efficient harvesting of microalgae containing high omega-3 levels are critical concerns for industrial use. Aeration can elevate production of some microalgae by providing CO₂ and O₂. However, it may lower the production of others by generating shear stress, causing severe cell damage. The mixotrophic dinoflagellate Gymnodinium smaydae is a new, promising microalga for omega-3 fatty acid production owing to its high docosahexaenoic acid content, and determining optimal conditions and methods for high omega-3 fatty acid production and efficient harvest using G. smaydae is crucial for its commercial utilization. Therefore, to determine whether continuous aeration is required, we measured densities of G. smaydae and the dinoflagellate prey Heterocapsa rotundata in a 100-L semi-continuous cultivation system under no aeration and continuous aeration conditions daily for 9 days. Furthermore, to determine the optimal conditions for harvesting through centrifugation, different rotational speeds of the continuous centrifuge and different flow rates of the pump injecting G. smaydae + H. rotundata cells into the centrifuge were tested. Under continuous aeration, G. smaydae production gradually decreased; however, without aeration, the production remained stable. Harvesting efficiency and the dry weights of omega-3 fatty acids of G. smaydae + H. rotundata cells at a rotational speed of 16,000 rpm were significantly higher than those at 2,000-8,000 rpm. However, these parameters did not significantly differ at injection pump flow rates of 1.0-4.0 L min^-1. The results of the present study provide a basis for optimized production and harvest conditions for G. smaydae and other microalgae.

• Tuberculosis and Respiratory Diseases
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• 제45권1호
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• pp.176-183
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• 1998

연구배경: 기관지폐포세척술로 얻은 기관지폐포세척액의 총세포 숫자와 감별숫자는 특발성폐섬유증을 포함한 간질성 폐질환의 진단과 예후 및 치료방침의 결정에 유용한 검사방법이다. 그러나 기관지폐포세척액 처리 방법에 대한 표준 방법 (standard method)이 아직 정립되어 있지 않고, 병원마다 처리 방법이 상이한 경우가 많아 검사 결과의 해석에 어려움이 많은 실정이다. 이에 본 연구에서는 기관지폐포세척액의 처리방법 중에서 면거즈 (cotton gauze)로 걸르는 방법, 세척액의 원심 분리 후 재부유하는 방법, 기관지폐포세척액의 보관 시간등이 총세포숫자와 감별숫자에 미치는 영향을 관찰하였다. 방 법: 활동성 폐질환이 없는 6명의 사람에 대해서 기관지내시경을 하여 얻은 기관지폐포세척액을 모아서 siliconized glass tube에 분주한 후, 0, 1, 2, 4겹의 면거즈 (pore size: 1mm)로 걸른후 일부를 trypan blue로 염색한 후 hemocytometer로 총세포숫자를 계수하고 일부는 cytocentrifuge한 후 Wright-Giemsa stain을 하여 감별숫지를 하였다. 그리고 일부의 세척액을 두 겹의 거즈로 걸른 후에 원심분리(400g, 30min) 하고 RPMI1640으로 재부유액을 만들어 총세포숫자와 감별숫자를 하였다. 그리고 나머지는 $4^{\circ}C$ 냉장고에 보관하였다가 2시간, 24시간, 48시간 후에 각각 같은 방법으로 총세포숫자와 감별숫자를 하였다. 결 과: 기관지폐포세척액을 면거즈로 거르지 않은 경우와 여러겹의 면거즈로 걸른 경우 총세포숫자와 감별숫자에 차이가 없었으나 기관지폐포세척액을 면거즈로 거르지 않았을 경우 두 예(33%)에서 점액사 때문에 세포가 뭉치고 겹쳐져서 총세포숫자와 감별숫자가 어려웠다. 기관지폐포세척액을 원심분리하였을 경우 총세포숫자는 감소하였으나 ($24{\pm}18%$), 감별숫자에는 차이가 없었다. 보관시간에 따른 총세포숫자에 있어서 2시간 보관했을 경우에는 총세포숫자의 감소가 없었으나 24시간 이상 보관시 유의하게 감소하였으며 (24시간: $28{\pm}21%$, 48시간: $41{\pm}24%$), 감별숫자에 있어서는 보관시간에 따른 차이는 없었으나 48시간 보관시에는 세포변성으로 감별숫자가 어려웠다. 결 론: 기관지폐포세척액의 총세포숫자와 감별숫자를 위한 기관지폐포세척액의 처리과정에서 면거즈로 걸러서 두시간 아내에 처리하는 것이 좋으며 원심분리는 하지 않는 것이 좋을 것으로 생각된다.

• Parasites, Hosts and Diseases
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• 제21권1호
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• pp.41-48
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• 1983

The activity and distribution of aspartate aminotransferase (EC 2.6. 1. 1) and alanine aminotransferase (EC 2.6.1.2) in adult Fascicle hepatica have been studied. Fasciola hepatica was fractionated by differential centrifugation into nuclear, mitochondrial and cytosolic fractions. The activity of GOT and GPT was measured by the method of Reitman and Frankel. Isozyme patterns of those enzyme were also examined by DEAE-cellulose column chromatography. The results obtained were as follows; 1. The activity of aspartate and alanine aminotransferase was about 0.55 unit and 0.92 unit per 1g of Fascicle hepatica, respectively. 2. The activity of those enzymes was relatively low compared with those in mammalian tissues. 3. The distribution of aspartate aminotransferase in the subcellular organelles showed that 71% of the activity was in cytosolic, 24% in mitochondrial and 5% was in nuclear fraction. 4. About 22% of the total alanine aminotransferase activity was found in the mitochondrial fratstion, about 66% in the cytosolic fraction. 5. Aspartate aminotransferase from cytosolic fraction was separated into two types of isozymes, whereas alanine aminotransferase from cytosolic fraction gave only one active peak on DEAE-cellulose column chromatography.

• Journal of Microbiology and Biotechnology
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• 제6권3호
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• pp.189-193
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• 1996

Submicron-sized polymeric particles (SSPP) were used to remove nucleic acids and endotoxins from cell lysates. The positively charged SSPP selectively adsorb nucleic acids and endotoxins and form complexes with them. The complexes can be easily removed by sedimentation or centrifugation. The removal of nucleic acids and endotoxins using SSPP also can be accomplished in the presence of cell and cell debris. Therefore, nucleic acids and endotoxins can be removed in an initial step of the down-stream processes. In bakers yeast and E. coli lysate systems, the level of DNA could be reduced more than three orders of magnitudes and endotoxins more than seven orders of magnitudes concurrently willi the cell debris removal process using SSPP.

• Journal of Microbiology
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• 제35권4호
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• pp.354-359
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• 1997

Methods for the extraction of DNA from water sample were approximated. Four different procedures of DNA extraction were carried out with pellets obtained from centrifugation of 4 liter water samples. The recovery efficiency and purity of DNA extracted by each method from different sources were compared. DNA yield varied with extraction methods, Method I, which involves enzymatic and freeze-thaw lysis steps and phenol and phenol-chloroform purification of extracted nucleic acid, showed a significantly higher yield and purity than the other methods. The use of glass beads in the DNA extraction methods improved the purity of DNA suitable for PCR. Bovine serum albumin in the PCR reaction mixture was useful in reducing inhibitory effects of contaminants. The efficiency of an extraction method was determined by the detection of the aer of Aeromonas hydrophila with PCR. The lower limit of detection of A. hydrophila from seeded tap water was 2 CFU/ml in PCR when method I was used for DNA preparation.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권2호
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• pp.141-145
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• 2000

Entomopathogenic nematodes are being used for insect control. We purified a toxin secreted by the insect-pathogenic bacterium, Xenorhadbus nematophilus, which lives in the gut of entomopathogenic nematodes. Culture broth of X. nematophilus was separated by centrifugation and concentrated by ultration. The concentrated culture broth was applied to a DEAE Sephadex A-50 column, and proteins were eluted stepwise with increasing concentrations of KCI. Fractions column. The molecty weight of purified toxin was39 kDa on SDS-PAGE, and Fourier tranformed infrared (FTIR) spectroscopy indicated that this toxin could be a new protein exhiting the charactristics of C=O stretching peak near 1650cm-1.

• Preventive Nutrition and Food Science
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• 제3권4호
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• pp.379-381
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• 1998

An angiotensin converting enzyme (ACE) inhibitor was isolated and partially purified from bovine blood plasma. Bovine blood plasma was obtained after removing blood cells by centrifugation, followed by the addition of anticoagulant to whole bovine blood. To precipitate plasma proteins, bovine blood plasma was treated with 4% trichloroacetic acid (TCA) as a final concentration .An ACE inhibitor was isolated from TCA supernatnat, using ultrafiltration, gel permeation chormatography, and reverse-phase high pressure liquid chromatogrpahy. The ACE inhibitor purified from TCA supernatant had IC50 values of 9.4$\mu$M.

• 한국세라믹학회지
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• 제53권1호
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• pp.50-55
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• 2016

In order to make a highly ordered three-dimensionally macro-porous structure of zirconia ceramics, porogen precursors PMMA beads were prepared by emulsion polymerization using acrylic monomer. The monodisperse PMMA latex beads were closely packed by centrifugation as a porogen template for the infiltration of zirconium acetate solution. The mixed compound of PMMA and zirconium acetate was dried. According to the firing schedule, dry compacts of PMMA and zirconium acetate were calcined at $475^{\circ}C$ to obtain micro-, macro-, and meso- structures of polycrystalline zirconia with monodispersed porosity. Inorganic frameworks composed of $ZrO_2$ were formed and showed a three Dimensionally Ordered Microstructure [3DOM] of $ZrO_2$ ceramics. The obtained $ZrO_2$ skeleton was calcined at $710^{\circ}C$. The 3DOM $ZrO_2$ skeleton showed color tuning in solutions such as deionized [DI] $H_2O$ and/or methanol. The monodispersed crystalline micro-structure with micro/meso porosity was observed by FE-SEM.