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Tae Whan Kim - One of the best experts on this subject based on the ideXlab platform.
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dependence of the structural and optical properties on the cd Mol Fraction in cdxzn1 xte gaas heterostructures
Materials Research Bulletin, 2001Co-Authors: M. S. Jang, H. L. Park, D. U. Lee, D. C. Choo, Tae Whan KimAbstract:Abstract Lattice-mismatched Cd x Zn 1−x Te epilayers with various Cd Mol Fractions were grown on GaAs (100) substrates by Molecular beam epitaxy. X-ray difFraction patterns and Auger depth profiles showed that the grown layers were Cd x Zn 1−x Te epitaxial films. The photoluminescence spectra showed that the degenerate valence band splitting into the heavy hole and the light hole bands was observed as the Cd Mol Fraction increased, which originated from the increase of the strain magnitude due to the increase of the lattice mismatch between the Cd x Zn 1−x Te epilayer and the GaAs substrate. Raman spectra showed that the frequency of the longitudinal-optical mode decreased as the Cd Mol Fraction increased, which was caused by the decrease of the mode oscillator strength. These results provide important information on the structural and optical properties for improving optoelectronic devices qualities operating in the blue-green spectral region.
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Dependence of the structural and optical properties on the Cd Mol Fraction in CdxZn1−xTe/GaAs heterostructures
Materials Research Bulletin, 2001Co-Authors: M. S. Jang, H. L. Park, D. U. Lee, D. C. Choo, Tae Whan KimAbstract:Abstract Lattice-mismatched Cd x Zn 1−x Te epilayers with various Cd Mol Fractions were grown on GaAs (100) substrates by Molecular beam epitaxy. X-ray difFraction patterns and Auger depth profiles showed that the grown layers were Cd x Zn 1−x Te epitaxial films. The photoluminescence spectra showed that the degenerate valence band splitting into the heavy hole and the light hole bands was observed as the Cd Mol Fraction increased, which originated from the increase of the strain magnitude due to the increase of the lattice mismatch between the Cd x Zn 1−x Te epilayer and the GaAs substrate. Raman spectra showed that the frequency of the longitudinal-optical mode decreased as the Cd Mol Fraction increased, which was caused by the decrease of the mode oscillator strength. These results provide important information on the structural and optical properties for improving optoelectronic devices qualities operating in the blue-green spectral region.
Ari Laaksonen - One of the best experts on this subject based on the ideXlab platform.
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Surface Tensions and Densities of Sulfuric Acid + Dimethylamine + Water Solutions
Journal of Chemical & Engineering Data, 2004Co-Authors: Antti-p. Hyvärinen, Heikki Lihavainen, Kaisa Hautio, Tomi Raatikainen, Yrjö Viisanen, Ari LaaksonenAbstract:The surface tensions and densities of aqueous solutions of dimethylamine, (CH3)2NH, and sulfuric acid, H2SO4, were measured at 24.2 °C. Mol Fractions of dimethylamine were varied between 0 and 0.21 and of sulfuric acid between 0 and 0.48. The surface tension of the binary dimethylamine + water solution decreased exponentially as dimethylamine was added, from the surface tension of water (72 mN·m-1 at 25 °C) to the value of 34 mN·m-1 at the maximum dimethylamine Mol Fraction of 0.21. The surface tension of the ternary system did not change from that of water + sulfuric acid until a sufficient amount of dimethylamine was added to turn the solution alkaline. When the Mol Fraction of dimethylamine was more than double the Mol Fraction of sulfuric acid, the surface tension of the solution started to approach that of water + dimethylamine. Polynomial fits were applied to measured data sets of both surface tension and density. Results and fitting parameters are presented.
Roland Douce - One of the best experts on this subject based on the ideXlab platform.
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MGDG Synthase of Spinach Chloroplast Envelope: Properties of the Substrate Binding Sites
Plant Lipid Metabolism, 1995Co-Authors: Eric Maréchal, Maryse A. Block, Jacques Joyard, Roland DouceAbstract:Kinetic properties of the delipidated monogalactosyldiacylglycerol (MGDG) synthase with respect to the various diacylglycerol Molecules were first investigated in mixed micelles containing the partially purified enzyme, the substrate (diacylglycerol) and the detergent, according to the “surface dilution” kinetic model proposed by [1]. We concluded that MGDG synthase has different affinities for the diacylglycerol species tested: a lower affinity for C18:0/C18:0, C16:0/C16:0, C16:0/C18:l, C18:3/C18:3 (Km from 0.040 to 0.066 Mol-Fraction), a higher affinity for C16:0/C18:2, C18:l/C16:0, C18:0/C18:l, C18:l/C18:l (Km values from 0.024 to 0.031 Mol-Fraction), and an even higher affinity for C18:2/C18:2 with Km of 0.0089 Mol-Fraction. To provide further evidence for a physiological significance of these data, enzymatic assays were performed within envelope vesicles prepared from therMolysin-treated intact chloroplasts. Kinetic experiments suggested that MGDG synthase possesses distinct and independant binding sites for each substrate, UDP-galactose or diacylglycerol. This was verified by studying pattern of inhibition of MGDG synthase activity by UDP relatively to each substrate. Moreover, protection of MGDG synthase activity against citraconic anhydride (a specific reagent of lysines) by incubating with either UDP-gal or 1,2-diacylglycerol demonstrates that substrate binding is not ordered.
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Kinetic properties of monogalactosyldiacylglycerol synthase from spinach chloroplast envelope membranes.
The Journal of biological chemistry, 1994Co-Authors: Eric Maréchal, Maryse A. Block, Jacques Joyard, Roland DouceAbstract:We have investigated the functioning of monogalactosyldiacylglycerol (MGDG) synthase activity partially purified from spinach chloroplast envelope membranes, using mixed micelles containing diacylglycerol (the substrate for MGDG synthase), CHAPS (3-[(cholamidopropyl)dimethylammonio]-1- propanesulfonic acid), and phosphatidylglycerol. The presence of this anionic phospholipid was essential for optimal MGDG synthase activity because it strongly improves diacylglycerol solubilization by CHAPS. We have demonstrated that the "surface dilution" kinetic model proposed by Deems et al. (Deems, R.A., Eaton, B.R., and Dennis, E.A. (1975) J. Biol. Chem. 250, 9013-9020) is valid for MGDG synthase assayed in mixed micelles within a narrow range of CHAPS concentration. However, the experimental conditions we have set up in this study led to the description of defined equilibrium and kinetic parameters of the interaction of the envelope MGDG synthase with diacylglycerol. Two-substrate kinetic studies were performed with varied UDP-galactose Molar concentrations and varied dioleoylglycerol surface concentrations. The families of reciprocal plots obtained were shown to intersect at a single point of the 1/[substrate] axis thus demonstrating that MGDG synthase is a sequential, either random or ordered, bireactant system. Therefore, MGDG synthase possesses two distinct and independent substrate-binding sites, a hydrophilic one for UDP-galactose and a hydrophobic one for diacylglycerol. The dependence of kinetic parameters on the diacylglycerol Mol Fraction allows a comparison of the affinity of the enzyme for a wide range of diacylglycerol Molecular species. The Km values obtained were ranging between 0.0089 Mol Fraction (52 microM) for dilinoleoylglycerol (18:2/18:2) to 0.0666 Mol Fraction (416 microM) for distearoylglycerol (18:0/18:0), but the differences observed were not really related to the unsaturation of the Molecule since the Km value for dilinoleoylglycerol was much lower than that (0.040 Mol Fraction) for dilinoleoylglycerol (18:3/18:3). The Km values for dioleoylglycerol (18:1/18:1) and for the diacylglycerol Molecular species synthesized within chloroplasts, i.e. containing 18:1/16:0, were in the average range, i.e. lower than 0.030 Mol Fraction (around 170 microM).
M. S. Jang - One of the best experts on this subject based on the ideXlab platform.
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dependence of the structural and optical properties on the cd Mol Fraction in cdxzn1 xte gaas heterostructures
Materials Research Bulletin, 2001Co-Authors: M. S. Jang, H. L. Park, D. U. Lee, D. C. Choo, Tae Whan KimAbstract:Abstract Lattice-mismatched Cd x Zn 1−x Te epilayers with various Cd Mol Fractions were grown on GaAs (100) substrates by Molecular beam epitaxy. X-ray difFraction patterns and Auger depth profiles showed that the grown layers were Cd x Zn 1−x Te epitaxial films. The photoluminescence spectra showed that the degenerate valence band splitting into the heavy hole and the light hole bands was observed as the Cd Mol Fraction increased, which originated from the increase of the strain magnitude due to the increase of the lattice mismatch between the Cd x Zn 1−x Te epilayer and the GaAs substrate. Raman spectra showed that the frequency of the longitudinal-optical mode decreased as the Cd Mol Fraction increased, which was caused by the decrease of the mode oscillator strength. These results provide important information on the structural and optical properties for improving optoelectronic devices qualities operating in the blue-green spectral region.
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Dependence of the structural and optical properties on the Cd Mol Fraction in CdxZn1−xTe/GaAs heterostructures
Materials Research Bulletin, 2001Co-Authors: M. S. Jang, H. L. Park, D. U. Lee, D. C. Choo, Tae Whan KimAbstract:Abstract Lattice-mismatched Cd x Zn 1−x Te epilayers with various Cd Mol Fractions were grown on GaAs (100) substrates by Molecular beam epitaxy. X-ray difFraction patterns and Auger depth profiles showed that the grown layers were Cd x Zn 1−x Te epitaxial films. The photoluminescence spectra showed that the degenerate valence band splitting into the heavy hole and the light hole bands was observed as the Cd Mol Fraction increased, which originated from the increase of the strain magnitude due to the increase of the lattice mismatch between the Cd x Zn 1−x Te epilayer and the GaAs substrate. Raman spectra showed that the frequency of the longitudinal-optical mode decreased as the Cd Mol Fraction increased, which was caused by the decrease of the mode oscillator strength. These results provide important information on the structural and optical properties for improving optoelectronic devices qualities operating in the blue-green spectral region.
M. F. Churbanov - One of the best experts on this subject based on the ideXlab platform.
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thermodynamic properties of ge0 25 ygayte0 75 xix glasses y 0 10 0 15 x 0 0 06 Mol Fraction for optical applications
Thermochimica Acta, 2020Co-Authors: А.d. Plekhovich, Alexander Velmuzhov, N.s. Zernova, A M Kutin, M. F. ChurbanovAbstract:Abstract For the obtained high-purity glasses of crystallization-resistant compositions Ge0.25-yGayTe0.75-xIx (y = 0.10, 0.15, x = 0-0.06 Mol Fractions) by method TM-DSC heat capacity experimentally determined and glass transition characteristics studied. Based on the results of theoretical processing of calorimetric data, standard thermodynamic functions were calculated in the temperature range 0–530 K which are complemented by temperature dependences of density and coefficient of thermal expansion. These thermodynamic functions are necessary for determining the conditions of synthesis by minimizing the Gibbs energy of promising representatives of the glass-forming system Ge–Ga–Te–I and prediction of the properties of glasses including those with functional additives that determine their optical-sensory applications.
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Thermodynamic properties of Ge0.25-yGayTe0.75-xIx glasses (y = 0.10, 0.15; x = 0 – 0.06 Mol Fraction) for optical applications
Thermochimica Acta, 2020Co-Authors: А.d. Plekhovich, A. M. Kut’in, Alexander Velmuzhov, N.s. Zernova, M. F. ChurbanovAbstract:Abstract For the obtained high-purity glasses of crystallization-resistant compositions Ge0.25-yGayTe0.75-xIx (y = 0.10, 0.15, x = 0-0.06 Mol Fractions) by method TM-DSC heat capacity experimentally determined and glass transition characteristics studied. Based on the results of theoretical processing of calorimetric data, standard thermodynamic functions were calculated in the temperature range 0–530 K which are complemented by temperature dependences of density and coefficient of thermal expansion. These thermodynamic functions are necessary for determining the conditions of synthesis by minimizing the Gibbs energy of promising representatives of the glass-forming system Ge–Ga–Te–I and prediction of the properties of glasses including those with functional additives that determine their optical-sensory applications.