• Title/Summary/Keyword: 화학반응성

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Chimooite, a New Mineral from Dongnam Mine, Korea (동남광산에서 발견된 신종광물 Zn­란시아이트(치무석))

  • 최헌수;김수진
    • Journal of the Mineralogical Society of Korea
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    • v.16 no.4
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    • pp.333-339
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    • 2003
  • A new mineral, Zn analogue of rancieite (Chimooite), has been discovered at the Dongnam mine, Korea. It occurs as compact subparallel fine­grained flaky or acicular aggregates in the massive manganese oxide ores which were formed by supergene oxidation of rhodochrosite­sulfide ores in the hydrothermal veins trending NS­N25E and cutting the Pungchon limestone of the Cambrian age. The flakes of chimooite are 0.2 mm for the largest one, but usually less than 0.05 mm. The acicular crystals are elongated parallel to and flattened on (001). This mineral shows gradation to rancieite constituting its marginal part, thus both minerals are found in one and the same flake. Color is bluish black, with dull luster and brown streak in globular or massive aggregates. Cleavage is perfect in one direction. The hardness ranges from 2.5 to 4. Under reflected light it is anisotropic and bireflectant. It shows reddish brown internal reflection. Chemical analyses of different parts of both minerals suggest that rancieite and chimooite constitute a continuous solid solution series by cationic substitution. The empirical chemical formula for chimooite has been calculated following the general formula, $R_2_{x}$ M $n^{4+}$$_{9­x}$ $O_{18}$ $.$n$H_2O$ for the 7 $\AA$ phyllomanganate minerals, where x varies from 0.81 to 1.28 in so far studied samples, thus averaging to 1.0. Therefore, the formula of Zn­rancieite is close to the well­known strochiometric formula $_Mn_4^{4+}$ $O_{9}$ $.$4$H_2O$. The mineral has the formula (Z $n_{0.78}$N $a_{0.15}$C $a_{0.08}$M $g_{0.01}$ $K_{0.01}$)(M $n^{4+}$$_{3.98}$F $e^{3+}$$_{0.02}$)$_{4.00}$ $O_{9}$ $.$3.85$H_2O$, thus the ideal formula is (Zn,Ca)M $n^{4+}$$_4$ $O_{9}$ $.$3.85$H_2O$. The mineral has a hexagonal unit ceil with a=2.840 $\AA$ c=7.486 $\AA$ and a : c = 1 : 2.636. The DTA curve shows endothermic peaks at 65, 180, 690 and 102$0^{\circ}C$. The IR absorption spectrum shows absorption bands at 445, 500, 1630 and 3400 c $m^{1}$. The mineral name Chimooite has been named in honour of late Prof, Chi Moo Son of Seoul National University.ity.versity.ity.y.

Geochemical Exploration for a Potential Estimation on the Carlin-type Gold Mineralization in Northern Mt. Taebaek Mining District, Korea (태백산 광화대 북부에서 칼린형 금광화작용 부존 잠재력 평가를 위한 지구화학 탐사)

  • Sung, Kyu-Youl;Park, Maeng-Eon;Yun, Seong-Taek;Moon, Young-Hwan;Yoo, In-Kol;Kim, Ryang-Hee;Shin, Jong-Ki;Kim, Eui-Jun
    • Economic and Environmental Geology
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    • v.40 no.5
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    • pp.537-549
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    • 2007
  • The characteristics of the mineralization and geology in the northern Mt. Taebaek mining district are found to be similar with those reported from Nevada district where the Carlin-type gold deposit occurs characteristically as repeated metallic ore deposits in space and time. Though two spots of hs and several spots of Sb anomalies were recognized in the Yeongweol area, they have no relationship with any metalliferous mineralization. On the other hand, two spots of As anomaly in the Jeongseon area have shown to be related with metalliferous ore deposits (mainly Ag-Au), and they are closely associated with Sb anomaly. Some elements of altered limestones in the study such as Au, Ag, As, Sb, Cu, Pb, Zn, and Mo area are closely associated together, and are more enriched in the Jeongseon area than in the Yeongweol area. In particular, Sb and As which may reflect the occurrence of the Carlin-type gold deposit are highly enriched. However, the base metals such af Zn and Pb are highly variable according to samples. The patterns of the enrichment factor for Sb and As, as well as those for Ag and Au, are very similar with those reported from the Carlin-type gold deposits in Nevada. These similarities in elemental distribution may imply that hydrothermal ore mineralization in the study areas was possibly originated from a fluid with the characteristics of the Carlin-type gold mineralization found in Nevada, China, and Indonesia. However, the pattern of base metals and Mo are different. This may result from different chemistry and/or mineralogy of host rock in the study areas.

A LONGITUDINAL STUDY OF THE ACHIEVEMENT AND EFFECTS OF THE SCIENTIFICALLY GIFTED STUDENTS WHO HAVE TAKEN A ULTRA HIGH SPEED ACCELERATED EDUCATION FOR THE EARLY ENTRANCE OF KAIST (KAIST 조기진학을 위해 초고속 속진학습을 받은 과학영재들의 성취정도와 효과에 대한 종단연구)

  • Yuk, Keun-Cheol;Moon, Jeong-Hwa
    • Journal of Gifted/Talented Education
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    • v.14 no.2
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    • pp.1-18
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    • 2004
  • This study attempted to survey the present status of the eight students who, 17 years from now, had participated in a special program for 170 days preparing for early entrance to the KAIST. With six students who responded to the questionnaire previously sent, the study focused on each participant's achievement at present, his evaluation on Accelerated Education, his personal opinions on early entrance to university and Gifted Science Education. From the survey, we could find out that three participants had received a doctorate and they are currently working as researchers at research center or professors at university. The other three participants are working as researchers at research center after receiving the M. S. Academic achievements vary according to each participant, but three of them, who ranked high in research achievement, had their articles published in international journals of the SCI level even when they were between 25 and 28 of age. Two of them in particular showed outstanding engineering and developing the commercial modem for IMT 2000 for the first time in Korea. One participant entered Harvard University to major in physics and afterwards studied the law in UCLA. He is now a professor in the law department. Concerning the evaluations on Accelerated Education and early entrance system, four participants answered positively while two participants expressed negative attitudes. When asked their opinions on the Gifted Education in Korea, such problems were pointed out as too much pressure of entering the first-class universities, the tendency to avoid choosing science-related major at universities, the lack of education system that encourages creative thinking, etc. It is necessary that the accelerated education play an important role to maximize their hidden potentials. It remains to be seen in what places these six participants will find themselves and of what ideas they will come up within the next 17 years. It will be worthwhile to wait until then for another survey.

Economic and Political Responses to Globalization: Economic Restructuring and Local Government as an Entrepreneur (세계화에 따른 경제${\cdot}$정치적 동향: 경제재구조와 기업가로서의 지방정부)

  • Koh, Tae-Kyung
    • Journal of the Korean Geographical Society
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    • v.31 no.4
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    • pp.662-671
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    • 1996
  • Since the world's economic and political structures have changed, the term 'globlization' has shown up as a dominant power and as a necessity for regional and national development. Each nation is responding to the globalization process economically and politically in various ways. In general, however, the economic response to the globalization is economic restructuring from the Fordist industries to 'flexible specialization'. And the political response to the globalization is 'global localization' as a new type of local politics(i.e., local policy activism or growth-enhancing local development policies). The crisis of Fordism shifted the role of local governments towards more involovement with local economic development. Local governments are mobilizing for loca economic development, they are taken into a process of institutional change that tends to redefine their responsibilities inside the state. Local governments thus tend to act as an entrepreneur in order to restructure theiir local economies and to compete with other national and international regions. State restructuring towards enerepreneurialism and efficient regional policy pursuing a pro-growth coalition trategy is chosen as a new mode of regulation for the post-Fordism at the local level. The flexible specialization as the post-Fordist economy and the local government as an entrepreneur are the global choice for globalization and a post-Fordist society. The paper focuses on the regulation theory which comprises the political economic perspective on resturcturing. Economic restructuring and state restructuring will be discussed in detail. And the paper tries to combine the economic globalization and the global localization as economic and political responses to globalization.

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The development of anti-DR4 single-chain Fv (ScFv) antibody fused to Escherichia coli alkaline phosphatase (대장균의 alkaline phosphatase가 융합된 anti-DR4 single-chain Fv (ScFv) 항체의 개발)

  • Han, Seung Hee;Kim, Jin-Kyoo
    • Korean Journal of Microbiology
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    • v.52 no.1
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    • pp.10-17
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    • 2016
  • Enzyme immunoassay to analyze specific binding activity of antibody to antigen uses horseradish peroxidase (HRP) or alkaline phosphatase (AP). Chemical methods are usually used for coupling of these enzymes to antibody, which is complicated and random cross-linking process. As results, it causes decreases or loss of functional activity of either antibody or enzyme. In addition, most enzyme assays use secondary antibody to detect antigen binding activity of primary antibody. Enzymes coupled to secondary antibody provide a binding signal by substrate-based color development, suggesting secondary antibody is required in enzyme immunoassay. Additional incubation time for binding of secondary antibody should also be necessary. More importantly, non-specific binding activity caused by secondary antibody should also be eliminated. In this study, we cloned AP isolated from Escherichia coli (E. coli) chromosome by PCR and fused to) hAY4 single-chain variable domain fragment (ScFv) specific to death receptor (DR4) which is a receptor for tumor necrosis factor ${\alpha}$ related apoptosis induced ligand (TRAIL). hAY4 ScFv-AP expressed in E. coli showed 73.8 kDa as a monomer in SDS-PAGE. However, this fusion protein shown in size-exclusion chromatography (SEC) exhibited 147.6 kDa as a dimer confirming that natural dimerization of AP by non-covalent association induced ScFv-AP dimerization. In several immunoassay such as ELISA, Western blot and immunocytochemistry, it showed antigen binding activity by color development of substrates catalyzed by AP directly fused to primary hAY4 ScFv without secondary antibody. In summary, hAY4 ScFv-AP fusion protein was successfully purified as a soluble dimeric form in E. coli and showed antigen binding activity in several immunoassays without addition of secondary antibody which sometimes causes time-consuming, expensive and non-specific false binding.

Funtional Components of Holophyte - Antioxidant substances in Salicornia herbacea L. - (염생식물의 기능 - 퉁퉁마디(S.hrebacea)의 항산화능 -)

  • Kim, Jong-Bae;Choe, Sun-Nam;Choe, Kyu-Hong;Lim, Seong-Han;Chai, Suk-Jin
    • Journal of Fisheries and Marine Sciences Education
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    • v.19 no.2
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    • pp.197-205
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    • 2007
  • This study was to investigate the chemical content and antioxidant activity by the part of Salicornia herbacea as part of using Salicornia herbacea as materials of functional foods. On a basis of the materials, this study was to clarify the nutritional excellence, chemical composition, and antioxidant activity of Salicornia herbacea. From the result of this research above, it may be summed up as follows.The Salicornia herbacea used in the experiment contained the moisture and crude fiber in the stalks a lot, and the protein, fat, and ash in the branches more. As to the content of free amino acid, the content of arginine took in the branches and stems most. Then, it contained threonine, glycine, tryptophan, valine, isoleucine, and lysine, etc. in the branches a lot. Also, it contained threonine, glutamic acid, tyrosine tryptophan alanine, and isoleucine in the stalks a lot. It was shown to be contained of essential amino acids like isoleucine, leucine, threonine, valine, methionine, lysine, phenylalanine, and tryptophan in the branches and steams more. As to the content of fatty acid in Salicornia herbacea, it found out that it contained the unsaturated fatty acid more than the saturated fatty acid. It took the content of eicosenoic acid(20:1) in the branches and stalks most. And then, it contained linoleic acid(18:2), pehtadecenoic acid(15:1), palmitic acid(16:0), and oleic acid(18:1), etc. a lot. As to the antioxidant activity in Salicornia herbacea using the DPPH radical, it was shown to be existed in the largest antioxidant activity when the concentration of methanolextract from Salicornia herbacea was 1 mM. There was higher antioxidant activity than 100 ppm BHT used as control plot when the concentration of methanol extract from the stalks was $100{\mu}M$. From the result of experiment above, Salicornia herbacea contained the essential amino acid a lot. It will be possible to be used as natural antioxidants because it has excellent antioxidant effect. Therefore, this researcher concludes that it will be available in using it as materials of functional foods.

Antioxidative Activity and Component Analysis of Cayratia japonica Extract (오렴매 추출물의 항산화 활성, 성분 분석)

  • Yang, Hee-Jung;Kim, Eun-Hee;Park, Soo-Nam
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.34 no.2
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    • pp.117-127
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    • 2008
  • In this study, the antioxidative effects, inhibitory effects on elastase, and components of Cayratia japonica extracts were investigated. The free radical(1,1-diphenyl-2-picrylhydrazyl, DPPH) scavenging activities($FSC_{50}$) of extract/fractions of Cayratia japonica were in the order: 50% ethanol extract(114.3 ${\mu}g/mL$)${\mu}g/mL$)${\mu}g/mL$). Reactive oxygen species(ROS) scavenging activities($OSC_{50}$) of some Cayratia japonica extracts in $Fe^{3+}-EDTA/H_2O_2$ system were investigated using the luminol-dependent chemiluminescence assay. The order of ROS scavenging activities were deglycosylated flavonoid aglycone fraction($OSC_{50},\;3.30{\mu}g/mL$)<50% ethanol extract(1.21 ${\mu}g/mL$)${\mu}g/mL$). Ethyl acetate fraction showed the most prominent scavenging activity. The protective effects of extract/fractions of Cayratia japonica on the rose-bengal sensitized photohemolysis of human erythrocytes were investigated. The Cayratia japonica extracts suppressed photohemolysis in a concentration dependent manner($1{\sim}25{\mu}g/mL$), particularly deglycosylated flavonoid aglycone fraction exhibited the most prominent celluar protective effect(${\tau}_{50}$, 175.05min at 25 ${\mu}g/mL$). Aglycone fractions obtained from the deglycosylation reaction of ethyl acetate fraction among the Cayratia japonica extracts, showed 2 bands in TLC and 2 peaks in HPLC experiments(360 nm). Two components were identified as luteolin(composition ratio, 47.50%), apigenin(52.50). TLC chromatogram of ethyl acetate fraction of Cayratia japonica extract revealed 3 bands and HPLC chromatogram showed 4 peaks, which were identified as luteolin-7-O-${\beta}$-D-glucopyranoside(composition ratio, 11.14%), apigenin-7-O-${\beta}$-D-glucuronopyranoside(15.38%), luteolin(23.55%) and apigenin(49.92%) in the order of elution time. The inhibitory effect of aglycone fraction on elastase($IC_{50},\;70.5{\mu}g/mL$) was very high. These results indicate that extract/fractions of Cayratia japonica can function as antioxidants in biological systems, particularly skin exposed to UV radiation by scavenging $^1O_2$ and other ROS, and protect cellular membranes against ROS. And component analysis of Cayratia japonica extract and antioxidative effects could be applicable to new cosmetics.

A STUDY ON THE ENAMEL EROSION BY FERMENTED MILKS (수종 유산균 발효유의 법랑질 침식효과에 대한 연구)

  • Sim, Jeung-Ho;Jeong, Tae-Sung;Kim, Shin
    • Journal of the korean academy of Pediatric Dentistry
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    • v.31 no.4
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    • pp.555-563
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    • 2004
  • The pH of beverages is known to be low and have, therefore, been implicated in the increasing incidence of erosion. Erosion is believed to be the predominant cause of teeth wear in children and young adults, although there will always be a contribution from attrition and abrasion. The aim of the present study was to evaluate the effect of yogurt on the progression of erosive demineralization in human enamel using demineralization model in vitro. In 4 yogurts, available on the market, pH, buffering capacity and the concentrations of calcium, phosphate and fluoride were determined. The buffering effect was determined by titration with NaOH. 50 milliliters of each drink was then titrated with 1M sodium hydroxide, added in 0.5 milliliters increments, until the pH reached about 7. Human deciduous enamel(n=40) samples were divided into four groups and exposed to 80ml of the yogurt for 30,60, 90 and 120min. Enamel surface microhardness(VHN) was examined before and after each exposure. 1. The average PH of fermented milk was 3.77 and this pH value was acidic enough to cause tooth erosion. 2. All of the fermented milks were found to be erosive(p<0.05) 3. The teeth exposed to the fermented milk all showed erosion like lesions and microhardness measurements showed that enamel surface hardness decreased proportionately with increased time of immersion in all tooth specimen groups. 4. After immersion for 30 and 60 minutes, reduction rate of microhardness values was not significantly different between the groups(p>0.05). However, after 90 and 120 minutes, reduction rate of each group was significantly different(p<0.05).

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Effects of Additives on the Improvement of Frozen Dough Quality (첨가물이 냉동반죽의 품질향상에 미치는 영향)

  • Lee, Young-Chun;Jeong, Hyung-Won;Yoon, Suk-Kwon
    • Korean Journal of Food Science and Technology
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    • v.36 no.2
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    • pp.217-225
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    • 2004
  • This study was carried out to reduce the loss of frozen dough quality during frozen storage. Using response surface method, ascorbic acid 160.4 ppm, L-cysteine 63.1 ppm, and SSL 0.6% were found to be optimum, with xanthan gum 0.3% (formula A) and Ultra tex-3 5% (formula B) added as cryoprotectants. During frozen storage at $-20^{\circ}C$, control rapidly deteriorated after 4 weeks, while formulas A and B showed slight deterioration with immutable quality after 10 weeks.

Decomposition Characteristics of Non-Degradable Liquid Waste under High Temperature and High Pressure Conditions (고온 고압 조건에서의 난분해성 액상폐기물 분해 특성)

  • Lee, Gang-Woo;Shon, Byung-Hyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.8 no.6
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    • pp.1572-1578
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    • 2007
  • The specified wastes consist of waste acid, waste alkali, waste oil, waste organic solvent, waste resin, dust, sludge, infectious waste, and others. Among these specified wastes, a great portion is liquid phase wastes. The purpose of this study is to develop the high temperature and high pressure (HTHP) treatment system for decomposition of the liquid phase specified waste (LPSW). For this, we analyzed the physical and chemical properties of the LPSW such as density, proximate analysis, ultimate analysis, heating values, and designed 0.3 ton/day HTHP treatment system. The LPSW tested in this experiment were prepared by adding TCE(trichloroethylene) and toluene to liquid phase waste which was brought into the commercial waste treatment company. The average density of waste oil (25 samples), waste resin (5 samples), and waste solvent (12 samples) was 0.99 g/mL, 0.91 g/mL, and 0.93 g/mL, respectively. And the average lower heating value of waste oil, waste resin, and waste solvent was 8,294 kcal/kg, 5,809 kcal/kg, and 7,462 kcal/kg, respectively. The DRE (Destruction & Removal Efficiency) of TCE and toluene were 99.95% and 99.73% at atmospheric pressure conditions and that were 99.99% and 99.82% at pressurized conditions, respectively. These results showed that TCE/toluene mixtures were properly decomposed over about 99.73% of DRE by the HTHP treatment system and pressurized conditions were more effective to destroy those pollutants than atmospheric pressure conditions. Also these systems could be directly applied to industries which try to treat the liquid phase specified waste within the regulation limit.

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