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Electrical and Optical Switching Characteristics of Gold-Doped P-I-N Diodes (금이 도우핑된 P-I-N 다이오드의 전기적 및 광학적 스위칭 특성)

  • Min, Nam-Ki;Ha, Dong-Sik;Lee, Seong-Jae
    • Proceedings of the KIEE Conference
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    • 1996.07c
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    • pp.1547-1549
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    • 1996
  • The electrical and optical switching characteristics of gold-doped silicon p-i-n diodes have been investigated. The device shows a dark switching voltage of about 500 V. The switching voltage decreases rapidly when the illumination level is increased. The differential sensitivity of optical gating over linear region is $d(V_{Th}/V_{Tho})/dP_{Ph}$=0.25/uW. The turn-on delay time and the turn-on rise time decrease with increasing optical pulse power. The turn-off delay and the fall time are negligible.

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Purification and Properties of Serratia marcescens Purine Nucleoside Phosphorylase. (Serratia marcescens Purine Nucleoside Phosphorylase의 정제 및 특성)

  • 방성권;신종란;최병범
    • Microbiology and Biotechnology Letters
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    • v.28 no.5
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    • pp.251-257
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    • 2000
  • Serratia marcescens purine nucleoside phosphorylase (PNP) was purfied to homogeneity by streptomycin sulfate treatment, Sephacry HR S-200 gel filtration chromatography and AMP-agarose affinity chromatography. The specific activity of the enzyme was increased 49-fold during purification with an overall yield of 7.0%. The molecular weight was 168kD as estimated by Sephadex G-150 gel filtration chromatography. The S. marcescens enzyme was composed of six identical subunits with subunit molecular weight of 28kD, as estimated by SDS-PAGE. The Km values of S. marcescens enzyme for inosine and deoxyinsoine were 0.38 and 1.20 mM, respectively. The ph optimum was near 8.0, and the enzyme was relatively heat-stable protein. The enzyme was inactivated com-pletely by 0.5 mM of $Cu^{ 2+}$.

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FRENCH PROGRAM TOWARDS AN INNOVATIVE SODIUM COOLED FAST REACTOR

  • Martin, Ph.;Anzieu, P.;Rouault, J.;Serpantie, J.P.;Verwaerde, D.
    • Nuclear Engineering and Technology
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    • v.39 no.4
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    • pp.237-248
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    • 2007
  • Sodium-cooled fast reactor is considered in France as a potential candidate for a prototype of 4th generation system to be built by 2020. A detailed working program has been launched recently to identify by 2012 the potential improvement tracks for later industrial development of these reactors. The goals for innovation are first identified: Progress of the safety with a special attention to severe accidents risk minimization and mitigation (defense in depth approach); Economic competitiveness of the system mainly by reducing the capital cost, the investment risks by enhancing in service inspection and repair capacities, and raising the availability; Sustainability with fissile material management while reducing the proliferation risk; capacity for long-lived waste transmutation.

Stereoselective Synthesis of Novel Bestatin Analogs (새로운 베스타틴 유사체의 입체선택적 합성)

  • Seo, Youngran;Lee, SooBeom;Kim, Young Gyu
    • Applied Chemistry for Engineering
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    • v.26 no.1
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    • pp.111-115
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    • 2015
  • Two new analogs of bestatin were prepared from $\small{D}$-leucine and $\small{D}$-valine in a stereoselective and efficient way. An aminopeptidase inhibitor bestatin shows significant biological effects on immunomodulation and is marketed for the treatment of acute myelocytic leukemia. The key intermediates, trans-oxazolidine methyl esters 2a and 2b, were obtained with more than 20 to 1 stereoselectivity in a one-pot procedure by the three cascade reactions between N-hydroxymethyl protected ${\alpha}$-amino aldehydes (4a and 4b) and phenylsulfonylnitromethane ($PhSO_2CH_2NO_2$) and the following in-situ ozonolysis. Basic hydrolysis of 2a and 2b, and then the peptide coupling with $\small{L}$-Leu-OMe produced the protected derivatives of two new bestatin analogs, 3a and 3b, respectively. The new isobutyl and isopropyl analogs of bestatin (1a and 1b) were produced in overall 51% and 38% yields, respectively, with high stereoselectivity from the corresponding protected ${\alpha}$-amino aldehydes 4 in a six-step process.

Determination of Heterocyclic Amines and Acrylamide in Agricultural Products with Liquid Chromatography-Tandem Mass Spectrometry

  • Lee, Kyung-Jun;Lee, Gae-Ho;Kim, HaeSol;Oh, Min-Seok;Chu, Seok;Hwang, In Ju;Lee, Jee-yeon;Choi, Ari;Kim, Cho-il;Park, Hyun-Mee
    • Toxicological Research
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    • v.31 no.3
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    • pp.255-264
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    • 2015
  • Heterocyclic amines (HCAs) and acrylamide are unintended hazardous substances generated by heating or processing of foods and are known as carcinogenic and mutagenic agents by the animal experiments. A simple method was established for a rapid and accurate determination of 12 types of HCAs (IQ, MeIQ, Glu-P-1, Glu-P-2, MeIQx, Trp-P-1, Trp-P-2, PhIP, $A{\alpha}C$, $MeA{\alpha}C$, Harman and Norharman) and acrylamide in three food matrices (non-fat liquid, non-fat solid and fat solid) by isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS). In every sample, a mixture of internal standards including $IQ-d_3$, $MeIQx-d_3$, $PhIP-d_3$, $Trp-P-2-^{13}C_2-^{15}N$ and $MeA{\alpha}C-d_3$ was spiked for quantification of HCAs and $^{13}C_3$-acrylamide was also spiked for the analysis of acrylamide. HCAs and acrylamide in sample were extracted with acetonitrile and water, respectively, and then two solid-phase extraction cartridges, ChemElut: HLB for HCAs and Accucat: HLB for acrylamide, were used for efficiently removing interferences such as pigment, lipid, polar, nonpolar and ionic compounds. Established method was validated in terms of recovery, accuracy, precision, limit of detection, limit of quantitation, and linearity. This method showed good precision (RSD < 20%), accuracy (71.8~119.1%) and recovery (66.0~118.9%). The detection limits were < 3.1 ng/g for all analytes. The correlation coefficients for all the HCAs and acrylamide were > 0.995, showing excellent linearity. These methods for the detection of HCAs and acrylamide by LC-MS/MS were applied to real samples and were successfully used for quantitative monitoring in the total diet study and this can be applied to risk assessment in various food matrices.

Tracer Study Using $H_2O^{18}$ on the Oxidation of Vanadium (III) by Molecular Oxygen (산소에 의한 바나듐 (III) 이온의 산화반응에 대한 $O^{18}$ 동위원소 연구)

  • Kim, Myeong Ja;Choe, Dong Sik
    • Journal of the Korean Chemical Society
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    • v.18 no.4
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    • pp.259-266
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    • 1974
  • Isotopic experiments using $H_2O^{18}$ on the oxidation of V(III) in acid perchlorate by molecular oxygen were performed in the range pH 1.0 to 3.0. At pH < 2, where a rate equation of the form TEX>$ -\frac{d[V(III)]}{dt}=k_1\frac{[O_2][V(III)]}{[H^+]}$ is adequate, the tracer study clearly indicated that all the product vanadyl ion's ($VO^{2+}$) oxygen originated from the molecular oxygen. At pH > ~2, where a different rate expression of the form $-\frac{d[V(III)]}{dt}=K_2\frac{[O_2][V(III)]^2}{[Ht]^2}$is required, the isotopic experiment showed that half the vanadyl oxygen originated from the molecular oxygen. Considering the results of the isotopic study, a mechanism for the V(Ⅲ)-O2 reaction at pH < ~2, may be suggested as follows: The tracer results at pH > ~2 imply that the rate determining step may be $$ V_2(OH)_2^{4+} + O_2 \rightarrow 2VO^{2+} + H_2O_2$$ followed by $$V_2(OH)_2^{4+} + H_2O_2 \rightarrow 2VO^{2+} + 2H_2O$$ after establishing the equilibria V^{3+} + H_2O \leftrightarrow VOH^{2+} + H^+, and 2VOH^{2+}\leftrightarrow V_2(OH)_2^{4+}$$

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A Study of Characteristics of lnxGa1-xP by Photoreflectance measurement (Photoreflectance 측정에 의한 InxGa1-xP의 특성 연구)

  • Kim D. L.;Yu J. I.
    • Laser Solutions
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    • v.8 no.3
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    • pp.5-10
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    • 2005
  • [ $InxGa_{1-x}P/GaAs$ ] structures were grown by chemical beam epitaxy(CBE), Pure phosphine($PH_3$) gases were used as group V sources. for the group III sources, TEGa, TmIn were used. $InxGa_{1-x}P$ epilayer was grown on SI-GaAs substrate and has a 1-${\mu}m$ thick. We have investigated the characteristics of $InxGa_{1-x}P$ by the photoreflectance(PR) spectroscopy, The PR spectrum of $InxGa_{1-x}P$ shows third-derivative feature whose Peaks Provide energy gap. The energy gap of $InxGa_{1-x}P$ has deduced composition x. From temperature dependance of PR spectra, temperature coefficient is $dEg/dT=-3.773{\times}10^{-4}$ eV/K, and Varshni coefficients $\alpha$ and $\beta$ values obtained $4{\times}10^4$ eV/K and 267 K respectively. Also, interaction $\alpha$B was 19.4 meV using the Bose-Einstein temperature relation, and $\Theta$ value related the average phonon frequency were 101.4 K. In particular, shoulder peak related to defects observed in PR signal that measured in temperature 82 K.

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Purification and Properties of Cyclodextrin Glucanotrnsferase Synthesizing $2-O-{\alpha}-D-Glucopyranosyl{\;}_{L}-Ascorbic$ Acid from Paenibacillus sp. JB-13

  • Bae, Kyung-Mi;Kim, Sung-Koo;Kong, In-Soo;Jun, Hong-Ki
    • Journal of Microbiology and Biotechnology
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    • v.11 no.2
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    • pp.242-250
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    • 2001
  • A Gram-positive bacterium (strain JB-13) that was isolated from soil as a producer of cyclodextrin glucanotransferase (CGTase) [EC 2.4.1.19] was identified as Panibacillus sp. JB-13. This CGTase could catalyze the transglucosylation reaction from soluble starch to L-ascorbic acid (AA). A main product formed by this enzyme with ${\alpha}-glucosidase$ was identified as $2-O-{\alpha}-D-glucopyranosyl{\;}_{L}-ascorbic$ acid (AA-2G) by the HPLC profile and the elemental analysis. CGTase was purified to homogeneity using ammonium sulfate fractionation, ion-exchange chromatography on DEAE-Seohadex A-50, and gel chromatography on Sephacryl S-200HR. The molecular weight was determined to be 66,000 by both gel chromatography and SDS-PAGE. The isoelectric point of the purified enzyme was 5.3. The optimum pH and temperature was PH 7.0 and $45^{\circ}C$ respectively. The enzyme was stable in the range of pH 6-9 and at temperatures of $75{\circ}C$ or less in the presence of 15 mM ${CaCl_2}.\;{Hg^2+},\;{Mn^+2},{Ag^+},\;and\;{Cu^2+}$ all strongly inhibited the enzyme's activity.

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Re-engineering Adult Education Programme-an Online Learning Curricular Perspective

  • Mathai, K.J.;Karaulia, D.S.
    • Journal of Korea Multimedia Society
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    • v.6 no.4
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    • pp.685-697
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    • 2003
  • The Web based multimedia programmes/courses are becoming widely available in recent years. Most of these courses focus on Behaviorist way of learning, which does not promote deep learning in any way. For Adults this approach further incapacitated, as it does not satisfy Andragogical needs. The search for Constructivist way of learning through the web applied to Indian conditions led to need for developing a curriculum development approach that would promote construction of knowledge through web based collaboration. This paper attempts to reengineer existing curriculum development processes and lays out a framework of‘Problem Based Online Learning (PBOL)’curriculum design. In this context, entire curriculum development life cycle is evolved and explained. This is a part of doctoral work (Ph.D), which is in progress and being undertaken by K.James Mathai, and guided of Dr.D.S.Karaulia.

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Changes of pH TBA, Meat Color and Sensory Evaluation on Duck Meat Fed Supplemental Bamboo Vinegar during Storage Period at 4$^{\circ}C$ (죽초액을 급여한 육용 오리고기의 저장기간 중 pH, 지방산패도, 육색 및 관능평가의 변화)

  • Kook, K.;Kim, K.H.
    • Korean Journal of Poultry Science
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    • v.29 no.4
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    • pp.287-292
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    • 2002
  • This study was conducted to investigate the changes of pH, TBA, meat color and sensory evaluation on duck meat fed supplemental Bamboo vinegar during storage period at 4$^{\circ}C$ . Experiment animals (five-wk-old, Cherry Valley F$_1$, 100 chicks) were randomly assigned in four treatment groups. Treatments were control, 1%, 2% and 4% based on Bamboo vinegar addition. There was no PH difference in breast meat between groups on day 1 of storage, while pH of bamboo vinegar supplemented group was sustained hi호 after 3 days. TBA values of Bamboo vinegar treated groups were significantly lower than control group (P<0.05) and were steady change during storage. The color value in lightness no difference between groups during the storage. The control was significantly increased in 6 d and 9 d, while the bamboo vinegar treated groups no difference during storage. The redness and yellowness in bamboo vinegar treatment were decreased in 3 d and 9 d storage. The decrease in yellowness was outstandingly observed in bamboo vinegar 1% and 2% treatment (P<0.05). The odor in terms of sensory evaluation was improved by supplemental bamboo vinegar treatment. The significant differences were observed on 1 d, 3 d and 6 d storage (P<0.05). The appearance of sensory evaluation of supplemental Bamboo vinegar treated groups (P<0.05) was significantly different in 1 d and 3 d storage. The results of this study indicate that the supplemental Bamboo vinegar 1% and 2% may improve meat quality during storage period in duck meat.