• 한국미생물·생명공학회지
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• 제38권4호
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• pp.385-390
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• 2010

청국장의 기호도를 개선하는 발효균으로 분리된 protease 생산균은 Bacillus licheniformis로 확인되었다. Protease 생산을 위한 배지를 최적화하기 위한 탄소원, 질소원, 인, 금속이온의 성분을 변화시키면서 균의 성장과 효소 생산성을 비교하였다. Glucose를 탄소원으로 사용하였을 때는 균의 성장은 정상적으로 일어나지만, protease 생산이 심하게 억제되는 것으로 나타났으며, Potato starch를 탄소원으로 사용하였을 때 효소 생산성이 가장 높았다. 질소원으로는 yeast extact가 효소 생산에 가장 적합하였다. 한편 2가 금속이온중 $Zn^{2+}$, $Cu^{2+}$, $Co^{2+}$을 배지에 첨가하였을 때는 균의 성장이 심하게 저해되었으며, 효소 생산도 되지 않았다. $CaCl_2$를 첨가한 배지에서는 균이 성장과 효소 생산성이 증가되었다. Potato starch(1.5%), yeast extract(1.5%), $CaCl_2$(0.7%), $K_2HPO_4$(0.03%)와 $KH_2PO_4$(0.03%)를 포함하는 것으로 구성된 최적화 배지에서 최대효소 생산성은 800 U/mL로 나타났으며 28시간 이후에는 배양액내 효소활성이 서서히 감소하였다.

• Environmental Analysis Health and Toxicology
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• 제20권1호
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• pp.87-95
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• 2005

Cadmium is well known as a toxic metal and has insulin mimicking effects in rat adipose tissue. This study was undertaken to investigate the effect of CdCl₂ on glucose transport and its mechanism in 3T3 - L1 adipocytes. CdCl₂ exhibits respectively 2.2 and 2.8 fold increases in the 2-deoxyglucose uptake when exposed to 10 and 25 μM of CdCl₂ for 12 hr. To investigate the stimulating mechanism of glucose transport induced by CdCl₂. Wortmannin and PD98059 were used respectively as PI3K inhibitor and MAPK inhibitor, which did not affect 2-DOG uptake. This results suggest that induced 2-deoxy-(l-3H)-D-glucose (2-DOG) uptake by CdCl₂ may not be concerned with the insulin signalling pathway. Whereas nifedipine, a calcium channel blocker inhibited the 2- DOG uptake stimulated by CdCl₂. In addition, we also measured the increased production of Reactive oxygen substances (ROS) and glutathione (GSH) level in 3T3-L1 adipocytes to investigate correlation between the glucose uptake and increased production of ROS with H2DCFDA. CdCl₂ increased production of ROS. Induced 2-DOG uptake and increased production of ROS by CdCl₂ were decreased by N-acetylcystein (NAC). And L-buthionine sulfoximine (BSO) a potent inhibitor of γ-GCS, decreased of 2-DOG uptake. Also NAC and BSO changed the cellular GSH level, but GSH/GSSG ratio remained unchanged at 10, 25 μM of CdCl₂.

• Elastomers and Composites
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• 제44권1호
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• pp.22-33
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• 2009

최근에 나노충전제를 낮은 부피 분율로 보강한 엘라스토머-나노복합체는 흥미 있는 물성 때문에 관심을 크게 불러 일으켰다. 특히 층화 규산염 클레이(clay), 카본 나노튜브(carbon nanotube), 나노섬유, 탄산칼슘, 금속 산화물 또는 실리카 나노입자 등과 같은 나노충전제를 탄성체에 혼입하면 기계적 물성, 내열성, 동적 기계적 물성, 화염지연성, 차단성 등이 크게 향상된다. 나노복합체의 물성은 크게 고분자 기질, 나노충전제의 성질과 이들의 혼입 방법에 좌우한다. 탄성체 기질 내에 나노충전제들의 균일한 분산은 원하는 물리적 특성과 기계적 특성을 얻기 위한 일반적 필수조건이다. 본 논문은 층화 규산염, 실리카(silica), 카본 나노튜브(carbon nanotube), 나노섬유와 여러 가지 다른 나노입자로 보강된 탄성체 나노복합체의 현재 개발 현황을 소개하였다.

• 대한치과보철학회지
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• 제41권2호
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• pp.243-257
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• 2003

The purpose of this study was to search the influences of the increase of the contents of sodium alginate in the experimental alginates on the some mechanical properties. 3 commercial alginates were selected for the purpose of comparison of the results of experiments. 7 experimental alginates were manufactured with the rise of contents of sodium alginate from 8.8% to 18.3% with the decrease of contents of diatomaceous earth and with the constant contents of calcium sulfate 12.5%. sodium phosphate 2.2%, zinc fluoride 2.0%. Splitable metal mold with 12.5mm diameter and 20.0mm height was filled with mixed alginate to prepare the cylinder shaped specimens. Strain in compression, elastic recovery, compressive strength were tested using the ISO specification number 1563, alginate impression material. Experimental groups were 7, and 10 specimens were used for each test items and each groups. Following results were obtained ; 1. Strain in compression was decreased with the increase of sodium alginate contents (p=0.0077, r2 = 0.6302). 2. Elastic recovery was decreased with the increase of sodium alginate contents but was not significant(p=0.0639, r2=0.7449). 3. Compressive strength was increased with the increase of sodium alginate contents (p<0.0001, r2 = 0.9617). These results mean that the increase of sodium alginate contents make alginate harder but may result the increased permanent deformation.

• 한국환경과학회지
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• 제7권2호
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• pp.141-148
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• 1998

Effects of alumlnlum(AA), soil pH and calcium(Cal on growth response and heavy metal accumulation and regulation of nitrogen fixation In Melilotus suaveolens seedlings, a biennial legume plant dominating in the disturbed area, were quantitatively analyzed during the growing periods. Accumulation of metals In each organ of M. suaveojens was Increased UC the lowering of pH. Al contents In leaf and root treat- ed with 30ppm Al at pH 4.2 on the 28th day after treatment were 8 and 11 folds higher than those of control, while the contents with 100ppm AA were 21 and 24 folds as compared to control. The significent inhibition in Al contents was induced by 100ppm AA and Ca at pH 6.5. Increased metals inhibited higher at pH 4.2 and the growth inhibition due to Al was reversed by the addition of Ca, suggesting that growth correlates to the pH value. Chlorophyll contents in leaves increased during growth stave were inhibited by Al treatments. The biomass was decreased UD the lowering of pH and the increase of concentrations. 100ppm Ca treatment resulted in 5.1-5.9% increase of the biomass as compared to that of 100ppm Al. Specific nitrogen fuation activities In nodules In the 100ppm Al at pH 4.2 and pH 6.5 were reduced to 35. 2% and 52.2% of control, on the 28th day after treatment, while the combination of Al and Ca induced reduced by 10% as compared to control with the treatment of 100ppm AA at pH 4.2 due to the inhibition bination of 100ppm Al and Ca and lowering of pH.

• Journal of Microbiology and Biotechnology
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• 제17권5호
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• pp.761-768
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• 2007

Serratia proteamaculans HY-3 isolated from the digestive tract of a spider produces an extracellular protease named arazyme, with an estimated molecular mass of 51.5 kDa. The purified enzyme was characterized as having high activities at wide pH and temperature ranges. We further characterized biochemical features of the enzymatic reactions under various reaction conditions. The protease efficiently hydrolyzed a broad range of protein substrates including albumin, keratin, and collagen. The dependence of enzymatic activities on the presence of metal ions such as calcium and zinc indicated that the enzyme is a metalloprotease, together with the previous observation that the proteolytic activity of the enzyme was not inhibited by aspartate, cysteine, or serine protease inhibitors, but strongly inhibited by 1,10-phenanthroline and EDTA. The araA gene encoding the exoprotease was isolated as a 5.6 kb BamHI fragment after PCR amplification using degenerate primers and subsequent Southern hybridization. The nucleotide sequence revealed that the deduced amino acid sequences shared extensive similarity with those of the serralysin family of metalloproteases from other enteric bacteria. A gene(inh) encoding a putative protease inhibitor was also identified immediately adjacent to the araA structural gene.

• 한국주조공학회지
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• 제26권6호
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• pp.267-271
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• 2006

Metal foam is a class of attractive materials, which exhibits unique combinations of physical, mechanical, thermal, electrical and acoustic properties. In particular, it is light and good at absorbing energy, which makes it attractive in automotive and aerospace applications weight is critical. In this paper, the Mg alloy foam was prepared by melt foaming method by addition of calcium as thickening agent, and $TiH_2$ or $CaCO_3$ powder as blowing agent. The macrostructural observation of foamed Mg showed that the pore structures of Mg alloy foam made by $CaCO_3$ as blowing agent were much better than that of foams made by $TiH_2$ as blowing agent. In addition, this paper showed the possible reason of fabrication magnesium alloy foam in proportion to blowing agent and the porosity range was about 40 to 76% as results value.

• Archives of Plastic Surgery
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• 제34권4호
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• pp.471-477
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• 2007

Purpose: Hydrofluoric acid(HF) is one of the most dangerous mineral acids with dissociated fluoride ions. As hydrofluoric acid is present in various household products(such as rust removers), a large population of industrials is at the risk of HF exposure. It is a very strong organic acid, used widely in glass etching, metal washing, and in the semiconductor industry. Even when using adequate safety measures, lack of care on the user's part results in chemical burn by HF. Symptoms caused by HF-induced chemical burns shows delayed manifestations resulting in a loss of proper treatment opportunities. We therefore reviewed 20 cases of HF-induced chemical burns and treatment principle. Methods: The objects of this study were 19 male patients and 1 female treated from March 2004 to March 2006. There were 19 cases of injury on digits and 1 on the wrist area. There were 15 cases of immediate treatment after sustaining HF-induced burns, and 5 cases of delayed treatment. As a principle, in the emergency treatment, partial or complete removal of the nail along with copious washing with normal saline was done, depending on the degree of HF invasion of the distal digital extremities. Results: The 15 cases who came to the hospital immediately after the injury were healed completely without sequelae, and those who delayed their treatment needed secondary surgical measures, due to the severity of inflammation and necrosis of the digital tissues. Conclusion: As the industrial sector develops, the use of HF is increasing more and more, leading to increase in incidences of HF-induced chemical burns. When treating chemical burns caused by HF, washing by copious amounts of normal saline, along with early removal of the nails, rather than calcium gluconate, seems to be a available method for preserving the shape and function of the digits and the nail. The education of patients regarding this subject should be empathized accordingly.

• Toxicological Research
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• 제12권1호
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• pp.69-79
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• 1996

Primary culture of cerebellar neuronal cells derived from 8-day old Long-Evans rats was used. Pure granule cells, astrocytes or mixed cells culture systems were prepared. These cells were differentiated and developed synaptic connections. And the astrocytes were identified by immunostaining with glial fibrillary acidic protein (GFAP). Methamphetamine (MAP), which acts on dopaminergic system and cadmium (Cd), a toxic heavy metal, were applied and biochemical assays and electrophysiological studies were performed. $LC_50$ values estimated by MTT assay of MAP and Cd were 3 mM and 2$\mu M$ respectively. Cells were treated with 1 mM or 2 mM MAP and 1$\mu M$ $CdCl_2$ for 48 hour, and the incubation media were analyzed for the content of released LDH. MAP (2 mM) and Cd significantly increased the LDH release. Cell viability was decreased in both groups and some cytopathological changes like cell swelling or vacuolization were seen. The cerebellar granule cells were used for measuring membrane currents using whole-cell clamp technique. Sodium and potassium currents were not affected by MAP neither Cd, but calcium current was significantly reduced by Cd but not affected by MAP. Therefore, in vitro neurotoxicity test system using neuronaI cells and astrocytes cultures were established and can be used in screening of potential neurotoxic chemicals.

• 방사성폐기물학회지
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• 제20권3호
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• pp.307-319
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• 2022

60+ Years of nuclear power generation has led to a significant legacy of radioactively contaminated land at a number of nuclear licenced "mega sites" around the world. The safe management and remediation of these sites is key to ensuring there environmental stewardship in the long term. Bioremediation utilizes a variety of microbially mediated processes such as, enzymatically driven metal reduction or biominerialisation, to sequester radioactive contaminants from the subsurface limiting their migration through the geosphere. Additionally, some of these process can provide environmentally stable sinks for radioactive contaminants, through formation of highly insoluble mineral phases such as calcium phosphates and carbonates, which can incorporate a range of radionuclides into their structure. Bioremediation options have been considered and deployed in preference to conventional remediation techniques at a number of nuclear "mega" sites. Here, we review the applications of bioremediation technologies at three key nuclear licenced sites; Rifle and Hanford, USA and Sellafield, UK, in the remediation of radioactively contaminated land.