• Title/Summary/Keyword: Metastable

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A Rheological Study of Topical Vehicles

  • Min, Shin-Hong;Rhee, Shanghi;Kim, Yong-Bae
    • Archives of Pharmacal Research
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    • v.2 no.2
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    • pp.89-97
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    • 1979
  • To find out the rheological characteristics of several pharamaceutical semisolid products, experiments were carriedout over the temperature range of 20 to 30 .deg.C . From continuous shear rheograms obtained with a Ferranti-Shirley cone and plate viscometer, loop area, shear rates, ryild values, limiting viscosities and activation energies were calculated. The systems were metastable and their viscosity decreased with time. As the temperature was raised, products studied showed a decrease in viscosity and yield value.

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Effects of Crystal Forms on Dissolution of Cephradin (세프라딘의 용출에 미치는 결정형의 영향)

  • Sohn, Young-Taek;Kim, Ji-Seon
    • Journal of Pharmaceutical Investigation
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    • v.28 no.2
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    • pp.115-119
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    • 1998
  • Five polymorphic modifications of Cephradin were prepared by recrystallization from organic solvents. The isolated crystal forms were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and X-ray crystallography powder diffractometry. Modificaition 1 was the most stable form and decomposed at $201.3^{\circ}C$. Modification 3 and 4 were metastable. The dissolution of modification 3 and 4 was faster than that of marketed form.

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Strengthening mechanisms of 304 stainless steel during strain aging (304 스테인리스강 시효처리 시 강화기구 고찰)

  • Lee, S.H.;Choi, C.Y.;Nam, W.J.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2009.05a
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    • pp.382-384
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    • 2009
  • Strengthening mechanisms of metastable austenitic stainless steel, containing $\alpha'$-martensite phase, during strain aging was investigated. The variations of volume fraction of $\alpha'$-martensite phase, hardness of $\alpha'$-martensite phase, hardness of austenite were examined.

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CHARACTERIZATION OF A HUMAN $\alpha_1$-ANTITRYPSIN VARIANT THAT IS AS STABLE AS OVALBUMIN BUT RETAINS INHIBITORY ACTIVITY

  • Lee, Kee-Nyung;Yu, Myeong-Hee
    • Proceedings of the Korean Biophysical Society Conference
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    • 1996.07a
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    • pp.14-14
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    • 1996
  • The metastable native state of proteins plays an important role in regulating biological functions. The native strain of serpins (serine protease inhibitors) are considered to be crucial for the inhibitory function. Several thermostable mutations of human $\alpha$$_1$-antitrypsin, a prototype inhibitory serpin, were identified in a systematic search targeted at the hydrophobic core of the molecule [Nature structural biology, vol. 3, no. 6, 497-500(1996)]. (omitted)

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MAGNETIC PROPERTIES OF THERMALLY ANNEALED $(Ni_{80}Fe_{20})_{1-x}Mn_x$ THIN FILMS

  • Kim, K. K.;Kim, C. K.;C. S. Yoon;Kim, S. J.
    • Proceedings of the Korean Magnestics Society Conference
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    • 2002.12a
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    • pp.190-191
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    • 2002
  • Granular feromagnets는 non-magnetic maxtrix 안에 nanometer-sized의 ferromagnetic grain들 구성된다. Co-Cu,Co-Ag, Fe-Ag, NiFe-Ag $^1$을 포함하는 이미 알려진 다른 Granular 금속 합금들의 giant magnetoresistance 에 관계하여 Granular feromagnets 에 대해 조사하였다. Bulk상태의 NiFe와 Mn 혼화되기 쉽다.$^2$ 그리고 Mn은 열처리된 다층박막의 NiFe의 lattice에 쉽게 수용되어진다.$^3$ 이번 실험에서는 metastable한 fcc solid solution NiFe-Mn 박막이 열처리 하에서 NiFe과 Mn으로 분리되었다. (중략)

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Regulation of the Inhibitory Function of $\alpha_1$-Antitrypsin by Native Metastability

  • Lee, Cheolju;Yu, Myeong-Hee
    • Proceedings of the Korean Biophysical Society Conference
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    • 1999.06a
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    • pp.41-41
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    • 1999
  • The native forms of some proteins such as inhibitory serpins (serine protease inhibitors) and viral membrane fusion proteins are metastable, which is critical to their functions. To understand the mechanism of how native metastability regulates the inhibitory function of serpins, we characterized stabilizing mutations of $\alpha$$_1$-antitrypsin, a prototype serpin, in which Gly 117 was replaced by a series of larger hydrophobic residues.(omitted)

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Observation of Penning ionization using the optogalvanic effect

  • Jeong, Kee-Ju;Lee, Jun-Hoi
    • Journal of Korean Vacuum Science & Technology
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    • v.7 no.1
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    • pp.18-22
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    • 2003
  • The optogalvanic effect is proposed and demonstrated as a technique for Penning ionization in a discharge of mixtures of metal vapors and rare gases. The gadolinium and argon mixture is used as a prototype. The lowest metastable of argon, 3P$_2$ (ls$\_$5/ in Paschen notation) at 93144 cm$\^$-1/, is within kT from the excited states of Gd ion. Thus Penning ionization occurs to an excited states of the ion. This process strongly alters the optogalvanic signal and has its own signatures.

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A Study on the photo-induced Optical Effects of Obliquely Deposited a-$Sc_{75} Ge_{25}$ Thin Films (층착각도에 따른 비정질 $Sc_{75} Ge_{25}$박마의 광유기 효과에 관한 연구)

  • 류희관;허희;김영호;정홍배
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.36 no.2
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    • pp.122-128
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    • 1987
  • In this paper, the photo-induced of a-$Sc_{75} Ge_{25}$thin films has been investigated as a function of annealing, exposure and obliqueness. The photo-induced effect consists of photo-thermal and photo-optical effect, which the photo-optical effect increases with increasing obliqueness. As the results, these photo-induced effects are related to the creation of atomic and electronic metastable state due to the surface defects.

Engineering a Non-Inhibitory Serpin, Ovalbumin

  • Jeoung, Yeon-Hee;Yu, Myeong-Hee
    • Proceedings of the Korean Biophysical Society Conference
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    • 1997.07a
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    • pp.38-38
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    • 1997
  • Serpins (serine protease inhibitor) are single polypeptide proteins of around 400 amino acids, and have a conserved secondary structure consisted of three ${\beta}$-sheets and nine ${\alpha}$-helices. Native conformation of inhibitory serpins is a metastable and requires conformational changes to inhibit target protease.(omitted)

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Determination of Lead in Steels by Hydride generation-Inductively Coupled Plama/Mass Spectrometry (수소화물 발생-유도결합플라스마 질량분석법에 의한 철강 중의 납의 정량)

  • Park, Chang Joon;Song, Sun Jin;Lee, Dong Soo
    • Analytical Science and Technology
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    • v.14 no.5
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    • pp.410-415
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    • 2001
  • An analytical method has been developed which determines lead in steel samples by inductively coupled plasma mass spectrometry (ICP-MS) with sample introduction by the hydride generation. The lead hydride is not stable and requires and oxidant for the oxidation into metastable Pb(IV) before reduction to $PbH_4$ with $NaBH_4$. A study was carried out to find and optimum lead hydride generation condition for a sample solution with more than $1000{\mu}g/mL$ Fe matrix. $K_2Cr_2O_7$ was found to work as an efficient oxidant when more than $10{\mu}g/mL$ Fe matrix was present. Lactic acid was used with the oxidant as a complexing agent of the metastable Pb(IV) to enhance sensitivity. Optimum concentrations of the sample acidity, oxidant and lactic acid were different depending on the matrix concentration. The isotope dilution method was employed for the quantitation of lead. The determined Pb concentrations of the NIST steel SRM 361 and 362 were in good agreement with the certified values within the uncertainty range.

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