• 제목/요약/키워드: $I_c$ degradation

검색결과 397건 처리시간 0.023초

황체호르몬 유리호르몬의 경점막 수송: 가토 점막균질액 중에서 중쇄지방산염의 LHRH에 대한 안정화 효과 (Transmucosal Delivery of Luteinizing Hormone-Releasing Hormone: Effect of Medium Chain Fatty Acid Salts on Stabilization of LHRH in Mucosal Homogenates in vitro.)

  • 한건;박정숙
    • 약학회지
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    • 제38권1호
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    • pp.67-77
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    • 1994
  • In order to investigate the feasibility of transmucosal delivery of the model peptide, LHRH, metabolism of LHRH and inhibition effect of medium chain fatty acid salts were studied in rabbit mucosal homogenate. LHRH incubated in homogenates of rectal(RE), nasal(NA) and vaginal(VA) mucosa were assayed by HPLC. Five to six degradation products of LHRH were deterted and the degradation of LHRH$(500\;{\mu}g/ml)$ followed the first order kinetics. The main degradation products were found as $LHRH^{1-5}(M-I)$, $LHRH^{1-3}(M-II)$ and $LHRH^{1-6}(M-III)$ by the method of amino acid analysis. The half-lives of LHRH in the mucosal homogenates were found to be less than 20 min at protein concentration of 2.5 mg/ml with the order of VA>NA>RE mucosal homogenate. Medium chain fatty acid salts such as sodium caprylate $(C_8)$, sodium caprate $(C_{10})$ and sodium laurate $(C_{12})$ at the concentration of $0.5%{\sim}1.0%$ inhibit the proteolysis of LHRH significantly. The addition of sodium laurate(0.5%) into the NA and VA mucosal homogenates protected LHRH completely from the degradation.

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Effect of Unsaturated Fatty Acids on Cellulose Degradation and Fermentation Characteristics by Mixed Ruminal Microbes

  • Hwang, I.H.;Kim, H.D.;Shim, S.S.;Lee, Sang S.;Ha, J.K.
    • Asian-Australasian Journal of Animal Sciences
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    • 제14권4호
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    • pp.501-506
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    • 2001
  • This experiment was conducted to evaluate the effects of supplemental unsaturated fatty acids (UFA) on fermentation characteristics, especially on gas production, cellulose degradation and volatile fatty acid (VFA) concentration by mixed ruminal microorganisms. In order to attain this objective, unsaturated fatty acids including oleic acid (C 18:1), linoleic acid (C18:2) and arachidonic acid (C22:4) were added at varying level. Mixed ruminal microbes used in this experiment were obtained from the rumen of a cannulated Holstein cow. Medium pH values after 7 d incubation were significantly affected by type and level of unsaturated fatty acids (p<0.01). All of UFA inhibited total gas production, and especially treatment of arachidonic acid at the levels of 0.01% gave the lowest gas. production after 7 d incubation (p<0.01). Comparison of the population of protozoa revealed that UFA did not have any significant effect on the total protozoa number. The addition of UFA did not effect dry matter degradation. Volatile fatty acid (VFA) composition of the culture was influenced little by UFA, although the considerable amount of iso-type VFA were detected in UFA supplemented incubations. The ratio of acetic acids to propionic acids, however, was lower than control in all the treatments after 7 d incubation (p<0.01).

Aspergillus awamori var. fumeus가 생성하는 효소의 Aflatoxin 분해특성 (Aflatoxin Degradation by an Enzyme from Aspergillus awamori var. fumeus)

  • 이찬;이성택;김영배
    • 한국미생물·생명공학회지
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    • 제20권4호
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    • pp.390-394
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    • 1992
  • Aspergillus awamori var. fumeus가 균체 밖으로 생산하느 aflatoxin 분해인자의 효소적 특성을 조사 하기위하여 그 배양 여액을 aflatoxin B1과 반응시킨 결과 1시간 동안 60의 기질을 분해하였다. 반응속도는 초기에 가장 높았으며 시간이 지날 수록 낮아졌다. 반응속도와 기질농도의 관계는 이중역수 식에서 직선을 보이며 겉보기 $K_m$$10.2{\mu}M$로 측정되었다. 최적온도 및 최적 pH는 각각 $30^{\circ}C$ 및 5로 나타났다. 반응은 분자상 산소를 요구하며 $Co^{2+}$에 의해서 촉진되나 $Fe^{2+}$, $Ca^{2+}$, $Zn^{2+}$, $Cu^{2+}$, 및 $Ba^{2+}$ 등의 이온에 의하여 저해되었다. 또한 KCN과 metyrapone에 의하여 저해되나, $NaIO_4$, cytochrome C 및 NADPH에 의한 영향은 관찰되지 않았다.

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Cr-Mo-V강의 전기화학적 분극 특성과 재질열화 평가 (An Evaluation on Electrochemical Polarization Characteristics and Material Degradation for Cr-Mo-V Steel)

  • 권일현;이송인;하정수;유효선
    • 비파괴검사학회지
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    • 제22권3호
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    • pp.267-274
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    • 2002
  • 본 연구는 Cr-Mo-V강의 다양한 분극특성들을 이용하여 비파괴적으로 재질열화를 평가하는 전기화학적 기법에 대해서 서술한 것이다. 사용된 전기화학적 기법은 스테인레스강의 열 이력에 의해 주로 야기되는 강화원소 결핍 영역에서의 예민화 그리고 부식속도를 평가하기 위해 널리 사용되는 양극분극 시험법이다. 재질열화 평가는 $10{\times}10{\times}0.5mm$ 크기의 시험편을 사용하는 미소역학 시험법으로 잘 알려진 SP시험에 의해 수행되었다. $630^{\circ}C$에서 1,000hrs 시효된 재료가 가장 높은 재질 열화도 ${\Delta}[DBTT]_{SP}$을 보였으나, 2,000hrs 그리고, 3,000hrs 시효된 재료는 시효 시간이 증가함에 따라 ${\Delta}[DBTT]_{SP}$의 감소를 보였다. 전류밀도의 차 $({\Delta}I_{FP},\;{\Delta}I_{SP})$가 1,000hrs 시효시간까지는 증가하였고, 그 이후의 시효시간에서는 시효시간의 증가와 더불어 감소됨이 관찰되었다. 이 같은 결과는 시효재료에 대한 경도의 거동과 일치하였다. 덧붙여, ${\Delta}[DBTT]_{sp}$${\Delta}I_{FP}$${\Delta}I_{SP}$와 같은 전기화학적 분극특성들과 좋은 상관관계를 가지고 있음을 알 수 있었다.

Identification of the bphC Gene for meta-Cleavage of Aromatic Pollutants from a Metagenomic Library Derived from Lake Waters

  • Moon Mi-Sook;Lee Dong-Hun;Kim Chi-Kyung
    • Biotechnology and Bioprocess Engineering:BBE
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    • 제9권5호
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    • pp.393-399
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    • 2004
  • Useful genes can be Screened from various environments by construction of metagenomic DNA libraries. In this study, water samples were collected from several lakes in mid Korea, and analyzed by T-RFLP to examine diversities of the microbial communities. The crude DNAs r were extracted by the SDS-based freezing-thawing method, and then further purified using an $UltraClean^{TM}$ kit (MoBio, USA). The metagenomic libraries were constructed with the DNAs partially digested with EcoR I, BamH I, and Sac II in Escherichia coli DH 10B using the pBACe3.6 vector. About 44.0 Mb of metagenomic libraries were obtained with average inserts 13-15 kb in size. The bphC genes responsible for degradation of aromatic hydrocarbons via mets-cleavage were identified from the metagenomic libraries by colony hybridization using the bphC specific sequence as a probe. The 2,3-dihydroxybiphenyl (2, 3-DHBP) dioxygenase gene (bphC ), capable of degradation of 2,3-DHBP, was cloned and its nucleotide Sequences analyzed. The genes consisted of 966 and 897 base pairs with an ATG initiation codon and a TGA termination codon. The activity of the 2,3-DHBP dioxygenase was highly expressed to 2,3-DHBP and Showed a broad substrate range to 2,3-DHBP, catechol, 3-methylcatechol and 4-methylcatechol. These results in-dicated that the bphC gene identified from the metagenomes derived from lake water might be useful in the development of a potent strain for degradation of aromatic pollutants.

Photocatalytic degradation of textile dye CI Basic Yellow 28 wastewater by Degussa P25 based TiO2

  • Konecoglu, Gulhan;Safak, Toygun;Kalpakli, Yasemen;Akgun, Mesut
    • Advances in environmental research
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    • 제4권1호
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    • pp.25-38
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    • 2015
  • Wastewaters of textile industry cause high volume colour and harmful substance pollutions. Photocatalytic degradation is a method which gives opportunity of reduction of organic pollutants such as dye containing wastewaters. In this study, photocatalytic degradation of C.I. Basic Yellow 28 (BY28) as a model dye contaminant was carried out using Degussa P25 in a photocatalytic reactor. The experiments were followed out at three different azo dye concentrations in a reactor equipped UV-A lamp (365 nm) as a light source. Azo dye removal efficiencies were examined with total organic carbon and UV-vis measurements. As a result of experiments, maximum degradation efficiency was obtained as 100% at BY28 concentration of $50mgL^{-1}$ for the reaction time of 2.5 h. The photodegradation of BY28 was described by a pseudo-first-order kinetic model modified with the langmuir-Hinshelwood mechanism. The adsorption equilibrium constant and the rate constant of the surface reaction were calculated as $K_{dye}=6.689{\cdot}10^{-2}L\;mg^{-1}$ and $k_c=0.599mg\;L^{-1}min^{-1}$, respectively.

Saccharomyces cerevisiae와 Pichia pastoris에서 Bovine Pancreatic Deoxyribonuclease I의 과발현과 특성 (Overexpression and Characterization of Bovine Pancreatic Deoxyribonuclease I in Saccharomyces cerevisiae and Pichia pastoris)

  • 조은수;김정환;윤기홍;김연희;남수완
    • 한국미생물·생명공학회지
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    • 제40권4호
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    • pp.348-355
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    • 2012
  • 본 연구에서는 S. cerevisiae와 P. pastoris에서 bovine pancreatic (bp-) DNase I의 과발현과 재조합 DNase I의 특성을 조사하였다. bp-DNase I 유전자는 GAL10 promoter, $MF{\alpha}$, GAL7 terminator 사이에 삽입하여 재조합 plasmid인 pGAL-$MF{\alpha}$-DNaseI (6.4 kb)를 구축하였다. 그리고 bp-DNase I 유전자를 AOX1 promoter, $MF{\alpha}$, AOX1 terminator 에 삽입하여 재조합 plasmid인 pPEXI (8.8 kb)를 구축하였다. 재조합 plasmid인 pGAL-$MF{\alpha}$-DNaseI과 pPEXI를 각각 S. cerevisiae와 P. pastoris 숙주세포에 형질전환시켰다. 형질전환된 효모세포들을 galactose와 methanol 배지에서 $30^{\circ}C$, 48시간 배양하면 bp-DNase I은 대부분이 배양 상등액으로 과발현되었다. P. pastoris 형질전환체는 배양 상등액에서 45.5 unit/mL의 DNase I 활성을 보였으며, 반면에 S. cerevisiae 형질전환체는 37.7 unit/mL의 DNase I 활성을 보였다. 또한 DNA 분해 특성을 조사한 결과, P. pastoris 재조합 DNase I으로 기질 DNA(calf thymus)를 처리하였을 때 1분 이내 DNA가 분해되는 것을 확인할 수 있었으며 이는 상업용 bp-DNase I과 S. cerevisiae 재조합 DNase I으로 처리했을 때보다 빠른 분해 패턴을 보였다.

몰드변압기용 에폭시 수지의 열 열화 특성에 관한 연구 (Study on the Thermal Degradation Properties of Epoxy Resin for the Cast Resin Transformer)

  • 남기동;정중일;허창수
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2000년도 하계학술대회 논문집 C
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    • pp.1572-1574
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    • 2000
  • In this paper, study on the properties of the thermal degradated epoxy resin which is used in cast resin transformer is performed to investigate the problems of the decreasing insulation characteristics and crack in the cast resin transformer. In the test, contact angle, weight loss, surface resistivity and relative dielectric constant are measured. As the results of the above measurements, the epoxy resin has increased to 150$^{\circ}C$ in the contact angle and surface resistivity but at the above 150$^{\circ}C$ the values have decreased. The relative dielectric constants have increased in the thermal treated samples with the degradation temperature. Consequently, the insulation properties of the epoxy resin which is used in cast resin transformer have increased by the 150$^{\circ}C$ but decreased in the above 150$^{\circ}C$.

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Polymer Passivation Effect on Methylammonium Lead Halide Perovskite Photodetectors

  • Kim, Hyojung;Byun, Hye Ryung;Kim, Bora;Kim, Sung Hyuk;Oh, Hye Min;Jeong, Mun Seok
    • Journal of the Korean Physical Society
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    • 제73권11호
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    • pp.1675-1678
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    • 2018
  • Methylammonium lead halide ($MAPbI_3$) perovskites are considered as promising materials owing to their excellent optical and electrical properties. However, perovskite materials suffer from degradation in air, which limits their practical applications. Here, we demonstrate successful passivation of the $MAPbI_3$ photodetectors through monochloro-para-xylylene (Parylene-C) deposition. The time-dependent photocurrent characteristics were systematically investigated, and we achieved significantly improved device performance and stability with Parylene-C passivation. Based on the excitation-power-dependent photoluminescence (PL) data, we confirmed that Parylene-C can reduce the carrier losses in $MAPbI_3$, leading to the enhancement of photocurrent and PL in $MAPbI_3$ photodetectors.

잎담배의 열분석 I. 열중량분석과 시차열분석 (Thermal Analysis of Tobacco Leaf I. Thermogravimetric and Differential Thermal Analysis)

  • 박영수;양광규
    • 한국연초학회지
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    • 제3권2호
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    • pp.89-93
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    • 1981
  • Some or the parameters affecting the thermal analysis of different types of ground tobacco have been discussed. The sample, Korean flue- cured and burley and Greek orient tobacco leaves were run in air at heating rate of $10^{\circ}$ and 20^{\circ}C$ per minute. The thermograms obtained were divided into four temperature zones. The effect of different heating rates on thermal degradation has been discussed At the lower heating rate the maxima of DTA curves in zone 3 and 4 were 25-$40^{\circ}C$ lower than that of the higher heating rate.

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