http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/11445 2026-05-16T10:50:53Z http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/13684 Physicochemical characteristics and fine structure of high-amylose wheat starches isolated from Australian wheat cultivars Hung P.V.; Maeda T.; Miskelly D.; Tsumori R.; Morita N. High-amylose starch is a source of resistant starch (RS) which have great impact on human health like dietary fiber. Nowadays, high-amylose wheat has been produced by genetic backcrossing, which enhances apparent amylose content and generates altered amylopectin. In this study, the high-amylose wheat starches isolated from various high-amylose wheat cultivars grown in Australia were characterized for understanding their physicochemical properties and fine structure of starch. The physicochemical characteristics of the high-amylose wheat starches are significantly different among the cultivars. Amylose contents of these cultivars were in a range of 28.0-36.9%, which is significantly higher than that of the normal wheat starch (25.6%). The high-amylose wheat starches also had higher blue value but lower λmax than the normal wheat starch. Gelatinization temperature of the high-amylose wheat starches is higher than that of the normal wheat starch but transition enthalpy is lower. X-ray diffraction showed that the high-amylose wheat starch had C-type crystals close to A-type crystal. Pasting properties of the high-amylose wheat starches were varying depending on the cultivars. However, almost high-amylose wheat starches had lower peak and final viscosities and higher setback viscosity than did the normal wheat starch. Fine structure of amylose and amylopectin was different among the high-amylose wheat cultivars and related to the physicochemical properties of starch. These results help to understand well the characteristics of the high-amylose wheat starches before application for food processing. © 2007 Elsevier Ltd. All rights reserved. 2008-01-01T00:00:00Z http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/13683 Existence and smoothness of solutions to second initial boundary value problems for Schrödinger systems in cylinders with non-smooth bases Hung N.M.; Son N.T.K. In this paper, we consider the second initial boundary value problem for strongly general Schrödinger systems in both the finite and the infinite cylinders QT, 0 < T ≤ +∞, with non-smooth base Ω. Some results on the existence, uniqueness and smoothness with respect to time variable of generalized solution of this problem are given. © 2008 Texas State University. 2008-01-01T00:00:00Z http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/13682 Electron mobility in Gaussian heavily doped ZnO surface quantum wells Quang D.N.; Tuan L.; Tien N.T. We present a theory of the low-temperature mobility of electrons in a Gaussian heavily doped zinc oxide surface quantum well (ZnO SFQW), taking into account both surface impurity and surface roughness scattering. The theory also includes strong confinement due to spontaneous polarization charges on the surface of ZnO. The electron distribution is found to be shifted closer to the surface for the O-polar face, while far away therefrom for the Zn-polar one. Accordingly, both scatterings are remarkably enhanced in the former case, while reduced in the latter one. Further, high-temperature Coulomb correlation among the charged impurities at a high density in a sample subjected to thermal treatment is proven to significantly reduce scattering by them. Therefore, in such a sample, surface roughness scattering dominates the electron mobility, while for a sample without thermal treatment, both scatterings are important. Our theory provides a good quantitative explanation of the experimental data on electron transport, in particular, the different carrier-density dependences of the mobilities measured in O-polar face ZnO SFQWs prepared in different ways, by bombardment with H2+ ions and by exposure to He+ ions, which has not been explained so far. © 2008 The American Physical Society. 2008-01-01T00:00:00Z http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/13681 Band-bending effects on the electronic properties of square quantum wells Quang D.N.; Tung N.H. We present a theory of the band-bending effects on two-dimensional (2D) carriers confined in a modulation-doped square quantum well. We develop a tractable variational evaluation of several physical quantities that are important in the theory of 2D systems. Analytic expressions of the envelope wave function and the 2D screening form factor allow us to compute various electronic properties such as electrical mobility, density of states in the presence or in the absence of magnetic fields, and Landau level broadening. We prove that in the case of the interface roughness scattering, the band-bending effects lead to a peak in the channel-width dependence of the mobility and a minimum in the Landau level broadening. Our modeling explains recent measurements for a 2D hole gas. © 2008 The American Physical Society. 2008-01-01T00:00:00Z