• 한국광물학회지
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• 제18권1호
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• pp.53-59
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• 2005

예천지역 화강섬록암 풍화단면내의 흑운모가 산화흑운모로 풍화되는 과정에서 Rb-Sr 동위원소연대의 변화를 분석하였다. 신선한 흑운모와 풍화된 흑운모들의 Rb-Sr 동위원소 조성을 열이온화질량분석기로 측정하였고, 이를 기존의 K-Ar 자료와 비교하였다. Rb-Sr 동위원소연대는 흑운모의 산화정도에 따라 체계적으로 감소하는 경향을 보이며, 이는 K-Ar 연대의 감소경향과 잘 일치하였다. Fe/sup 2+/의 산화로 발생하는 과잉전하로 구조내 양이온들이 방출되는 과정에서 층간의 방사기원핵종도 일부 방출되었는데, 일가 양이온인 /sup 87/Rb이 이가 양이온인 /sup 87/Sr로 붕괴되어 딸핵종인 /sup 87/Sr이 모핵종인 /sup 87/Rb보다 심하게 흑운모로부터 제거된 것으로 보이고, 그 결과 Rb-Sr 동위원소연대가 감소하였다. 풍화된 흑운모는 모암의 연대측정대상으로 부적합한 것으로 보이지만, 풍화과정에서 방사기원 동위원소들의 거동은 흑운모 풍화의 지화학적 및 구조적 과정에 대한 유용한 정보를 제공한다.

• Journal of Microbiology
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• 제33권3호
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• pp.244-251
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• 1995

An extracellular protease of Salmonella schottmulleri was purified from culture filtrate by using 0-75% ammonium sulfate precipitation, DEAE Sepharose Fast Flow ion exchange chromatography, Ultrogel HA chromatography and Sephacryl S-200 HR molecular sieve chromatography. To measure enzyme activity, synthetic dipeptide substrate (CBZ-arg-arg-AFC) with low molecular weight was employed as substrate. The molecular weight of the purified enzyme was approximately 80 kDa when determined by gel filtration on Sephacryl S-200 HR and 73 kDa when estimated by SDS-PAGE. The isoelectric point was 5.45. The activity of the purified enzyme was inhibited by metal chelating agesnts such as EDTA and 1.10-phenanthroline. The divalent cations, such as Ca$\^$2+/, Zn$\^$2+/, Fe$\^$2+/, Mg$\^$2+/ enhanced its activity. These results suggested that it was a metalloprotease. It had a narrow pH optimum of 6.5-7.5 with a maximum at pH 7.0 and a temperature optimum of 40.deg.C. It was stable at least for 1 week at 40.deg.C and maintained its activity for 24 hours at 50.deg.C, but it was rapidly inactivated at 65.deg.C. This protease was shown to be sensitive to sodium 50.deg.C, but it was rapidly inactivated at 65.deg.C. This protease was shown to be sensitive to sodium 50.deg.C, but it was rapidly inactivated at 65.deg.C. This protease was shown to be sensitive to sodium 50.deg.C, but it was rapidly inactivated at 65.deg.C. This protease was shown to be sensitive to sodium dodecyl sulfate (SDS) and was inactivated in a dose-dependent manner. However, it was resistant to Triton X-100 and the activity was enhanced to 32.3% with treatment of 0.025% Triton X-100.

• Molecules and Cells
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• 제40권5호
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• pp.355-362
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• 2017

The ${\beta}2$ integrins are cell surface transmembrane proteins regulating leukocyte functions, such as adhesion and migration. Two members of ${\beta}2$ integrin, ${\alpha}M{\beta}2$ and ${\alpha}X{\beta}2$, share the leukocyte distribution profile and integrin ${\alpha}X{\beta}2$ is involved in antigen presentation in dendritic cells and transendothelial migration of monocytes and macrophages to atherosclerotic lesions. ${\underline{R}}eceptor$ for ${\underline{a}}dvanced$ ${\underline{g}}lycation$ ${\underline{e}}nd$ ${\underline{p}}roducts$ (RAGE), a member of cell adhesion molecules, plays an important role in chronic inflammation and atherosclerosis. Although RAGE and ${\alpha}X{\beta}2$ play an important role in inflammatory response and the pathogenesis of atherosclerosis, the nature of their interaction and structure involved in the binding remain poorly defined. In this study, using I-domain as a ligand binding motif of ${\alpha}X{\beta}2$, we characterize the binding nature and the interacting moieties of ${\alpha}X$ I-domain and RAGE. Their binding requires divalent cations ($Mg^{2+}$ and $Mn^{2+}$) and shows an affinity on the sub-micro molar level: the dissociation constant of ${\alpha}X$ I-domains binding to RAGE being $0.49{\mu}M$. Furthermore, the ${\alpha}X$ I-domains recognize the V-domain, but not the C1 and C2-domains of RAGE. The acidic amino acid substitutions on the ligand binding site of ${\alpha}X$ I-domain significantly reduce the I-domain binding activity to soluble RAGE and the alanine substitutions of basic amino acids on the flat surface of the V-domain prevent the V-domain binding to ${\alpha}X$ I-domain. In conclusion, the main mechanism of ${\alpha}X$ I-domain binding to RAGE is a charge interaction, in which the acidic moieties of ${\alpha}X$ I-domains, including E244, and D249, recognize the basic residues on the RAGE V-domain encompassing K39, K43, K44, R104, and K107.

• 대한미생물학회지
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• 제22권2호
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• pp.109-116
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• 1987

As a process to establish an effective preventive measure of V. vulnificus septicemia, bactericidal effect of distilled water against V. vulnificus was studied. When about $2.0{\times}10^7\;CFU/ml$ of V. vulnificus was inoculated in distilled water, a dramatic decrease in the number of viable bacteria by 5 to $6LOG_{10}$ was observed in 5 minutes. Bactericidal kinetic curves could be divided into the first rapid killing phase until 1 minute and the later slow killing phase after then, showing the heterogeneity of the bacterial population inoculated. When V. vulnificus was inoculated in saline solutions having various salinities, significant decrease in the number of viable bacteria was noted only at salinities under 0.2%. The higher was the concentration of NaCl, the greater was the degree of protection against osmotic shock. When glucose, NaCl, $MgCl_2$, and $CaCl_2$ were diluted with deionized water to give same osmolarities and V. vulnificus was inoculated in each of them to compare the bactericidal curves plotted during the first 5 minutes after inoculation, the protection efficiencies were in the order of $MgCl_2>CaCl_2{\gg}NaCl{\gg}glucose$. Above results indicate that treatment(or thorough washing) of contaminated sea animals or other products with distilled water can be used as a preventive measure of V. vulnificus septicemia, and divalent cations can protect V. vulnifcus to osmotic shock with high efficiency.

• 자원환경지질
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• 제21권3호
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• pp.235-255
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• 1988

Talc deposit of pipe-like form occurrs in the lower part of the Hyangsanri Dolomite with a strike of N40 -50 E and a dip of 40 -50 NW which is one formation of the Ogcheon Super Croup. The pipi-like ore body plunge at about $40^{\circ}$ to the west and are parallel to the lineation developed in the area. Structural formulae of tales occurred in this deposit are close to the ieal composition $Mg_6Si_8O_{20}(OH)_4$ showing limited deviation from ideal one. Substitution of Al for Si in tetrahedral site is of little or nothing ranging 0-0.04 and octahedral occupancy is close to six ranging 5.88-5.98 atoms per unit cell. Predominant octahedaral cation is Mg and proportion of divalent cations is generally over 97percent. Calcite -dolomite thermometry is obtained by determining the mol % $MgCO_3$using of EPMA and XRD methods. The peak metamorphic temperature can be estimated at $470{\pm}30^{\circ}C$ in the area whereas carbonates occurred at near talc ore show lower temperature than $400^{\circ}C$ that the calcite solvus limit is not well established. It indicates that the talc deposit was formed at the lower temperature that the metamorphic temperature. Cosequently, the formation of talc by metamorphism is questionable and the alteratin zone developed around the talc ore is very limited. The occurrence of talc ore in the dolomite as well as mineralogy, calcite-dolomite geothermometry, chlorite geothermometry, field and microscopic evidence suggest that siliceous ascending hydrothermal solution along the fracture is responsible for the formation of talc. It was considered that the slight fracturing of dolomite was formed by deformation prior to the mineralization.

• Nutrition Research and Practice
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• 제10권1호
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• pp.19-25
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• 2016

BACKGROUND/OBJECTIVES: Cadmium is a toxic metal that is an occupational and environmental concern especially because of its human carcinogenicity; it induces serious adverse effects in various organs and tissues. Even low levels of exposure to cadmium could be harmful owing to its extremely long half-life in the body. Cadmium intoxication may be prevented by the consumption of dietary components that potentially reduce its accumulation in the body. Dietary chitosan is a polysaccharide derived from animal sources; it has been known for its ability to bind to divalent cations including cadmium, in addition to other beneficial effects including hypocholesterolemic and anticancer effects. Therefore, we aimed to investigate the role of dietary chitosan in reducing cadmium accumulation using an in vivo system. MATERIALS/METHODS: Cadmium was administered orally at 2 mg (three times per week) to three groups of Sprague-Dawley rats: control, low-dose, and high-dose (0, 3, and 5%, respectively) chitosan diet groups for eight weeks. Cadmium accumulation, as well as tissue functional and histological changes, was determined. RESULTS: Compared to the control group, rats fed the chitosan diet showed significantly lower levels of cadmium in blood and tissues including the kidneys, liver, and femur. Biochemical analysis of liver function including the determination of aspartate aminotransferase and total bilirubin levels showed that dietary chitosan reduced hepatic tissue damage caused by cadmium intoxication and prevented the associated bone disorder. CONCLUSIONS: These results suggest that dietary chitosan has the potential to reduce cadmium accumulation in the body as well as protect liver function and bone health against cadmium intoxication.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2012년도 임시총회 및 하계학술연구발표회
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• pp.121-122
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• 2012

Iron-excess gallium ferrite, $Ga_{0.6}Fe_{1.4}O_3$ (GFO), is known to have room-temperature ferromagnetic phases and potentially exhibit ferroelectricity as well [1]. But, leaky polarization-electric field (PE) hysteresis curves of the GFO thin film are hurdle to prove its spontaneous polarization, in other words, ferroelecticity. One of the reasons that the GFO films have leaky PE hysteresis loop is carrier hopping between $Fe^{2+}$ and $Fe^{3+}$ sites due to oxygen deficiency. We focus on reducing conducting current by substituting divalent cations at $Fe^{2+}$ sites. GFO thin films were grown epitaxially along b-axis normal to $SrRuO_3/SrTiO_3$ (111) substrates by pulsed laser deposition. Current density of the ion-substituted GFO thin films was reduced by $10^3$ or more. Ferroelectric properties of the ion-substituted GFO thin films were measured using macroscopic and microscopic schemes. In particular, local ferroelectric properties of the GFO thin films were exhibited and their remnant polarization and piezoelectric d33 coefficient were obtained.

• 산업식품공학
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• 제14권3호
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• pp.243-248
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• 2010

${\beta}$-Glucosidase 효소활성이 높은 균주를 선발하기 위하여 다양한 김치에서 분리된 젖산균의 ${\beta}$-glucosidase 활성을 탐색하였다. 김치에서 분리된 156개의 젖산균 중 134개의 균주만이 cellobiose를 탄소원으로 대사하였으며, 세포내 ${\beta}$-glucosidase 활성이 세포외 활성보다 현저히 높았다. 배추김치에서 분리된 W. cibaria KFRI88010 균주가 3.7${\pm}$0.5 unit/mg protein으로서 가장 높은 세포내 ${\beta}$-glucosidase 효소활성을 나타내었으며, 효소활성은 pH 5, ${37^{\circ}C}$ 반응조건에서 가장 높게 나타났다. $Mn^{2+}$를 비롯한 금속이온은 효소활성을 크게 저해하였다. W. cibaria KFRI88010 균주를 배양할 때 사용한 탄소원 중, fructose는 cellobiose나 glucose와 비교하여 약 2.5배 이상의 높은 세포내 ${\beta}$-glucosidase 효소활성을 나타내었다.

• 한국토양비료학회지
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• 제17권2호
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• pp.114-124
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• 1984

강원도(江原道) 경작지토양(耕作地土壤)을 대표(代表)할 수 있는 석회암(石灰岩)(평창군(平昌郡) 대화면(大和面)), 하성충적층지대(河成沖積層地帶)(춘천시(春川市) 우두동(牛頭洞), 원성군(原城郡) 문막면(文幕面)), 현무암지대(玄武岩地帶)(철원군(鐵原郡) 동송면(東松面))의 답토양(畓土壤)을 시료(試料)로 사용(使用)하여 CEC(양(陽) ion 교환용량(交換容量) : Cation exchange capacity) 측정방법간(測定方法間)의 차이(差異)와 문제점(問題點)을 검토(檢討)하였으며 또한 ion 강도(强度), pH, 치환(置換) ion의 변화(變化)가 토양(土壤) CEC에 미치는 영향(影響)을 조사(調査)하였다. CEC 측정방법(測定方法)은 방법간(方法間)의 공통과정(共通過程)인 포화(飽和), 유척(流滌), 치환(置換)의 과정(過程)에서 진탕기(振蕩器)와 원심분리기(遠心分離器)를 사용(使用)하는 방법(方法)이 Column을 사용(使用)하는 방법(方法)이나 여과기(濾過器)를 사용(使用)하는 방법(方法) 그리고 Brown법(法)보다 우수한 것으로 판단되었다. 포화(飽和) ion의 강도(强度)(농도(濃度))가 CEC에 미치는 영향(影響)은 일반적(一般的)으로 ion강도(强度)가 높을수록 포화회수(飽和回數)가 적으면서도 큰 CEC 값을 얻었으나 석회암지대(石灰岩地帶) 안미통(統) 토양(土壤)의 경우(境遇)는 1가(價) ion으로 포화시(飽和時) ion강도(强度)가 높거나 포화(飽和)횟수가 많을수록 CEC값이 감소(減少)하였다. 일반적(一般的)으로 토양(土壤)의 pH가 증가(增加)함에 따라 비례적(比例的)으로 CEC가 증가(增加)하였으나 하성충적층지대(河成沖積層地帶) 특(特)히 Al함량(含量)이 많은 춘천(春川) 규암통토양(統土壤)의 경우(境遇) pH가 5.5에서 7.5로 변(變)할 때 CEC의 급격(急激)한 상승(上昇)을 보였다. CEC 측정(測定)에 사용(使用)하는 양(陽) ion의 선택(選擇)은 일반적(一般的)으로 2가(價) ion으로 포화(飽和)하고 2가(價) ion으로 치환(置換)하는 것이 1가(價) ion을 사용(使用)할 때보다 높은 CEC 값을 나타내었다. 강원도(江原道) 토양(土壤)의 CEC의 70%는 유기물(有機物)에 의한 것이었다. 토양(土壤)의 CEC 측정시(測定時) 평창(平昌)과 원성토양(原城土壤)은 0.5M 2가(價) ion 용액(溶液)으로 2~3회(回), 철원토양(鐵原土壤)은 3~4회(回) 포화(飽和)하고 치환(置換)은 0.25M 2가(價) ion 용액(溶液)으로 3회정도(回程度) 행(行)하는 것이 바람직 하였다.

• 한국건축시공학회지
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• 제16권3호
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• pp.219-227
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• 2016

본 연구에서는 염해에 열화작용을 일으키는 염소이온을 고정하기 위한 방안으로 이온교환능력과 흡착능력이 우수하다고 알려진 층상이중수산화물(LDHs)을 활용하였다. 실험에 앞서 두 종류의 LDHs(Mg/Ca)를 공침법을 사용하여 합성하였고, 합성된 고형물을 활용하여 수용액내에서 실험적 연구를 진행하였다. 일반적 합성법인 공침법으로 기존문헌의 입증된 나노 입자의 LDHs를 제조 할 수 있었으며 이는 건축재료로써의 적용에 앞서 간단한 제조방법만으로도 제조가 가능하다는 긍정적인 효과로 볼 수 있다. 또한, 이온교환시간 15분내에서는 Mg체계가 고정속도가 빨랐으나, 그 후의 시간에서는 최대 4시간까지 Ca체계의 고정량이 우수하였다. 임계치 $1.2kg/m^3$의 경우 0.5 g당 Mg/Ca은 각각 0.0035g, 0.0015g의 염소이온을 고정하였다. 또한, 효과가 우수했던 이온교환된 Ca체계를 XRD 분석한 결과 층간에 삽입한 $NO_3$가 용출되고 염소이온이 치환되었음을 알 수 있었다. 시멘트계의 적용시 Mg체계보다 Ca체계가 우수한 고정효과를 기대 할 수 있다고 판단되며, 향후 연구에서는 본 연구에 결과를 바탕으로 시멘트계 재료에서의 염소이온 고정효율을 평가하고자 한다.