Materials Literature
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We investigate the optical properties of nanoscale InAs quantum dots (QDs) in a Si matrix. At a growth temperature of 400 °C, the deposition of 7 ML InAs leads to the formation of coherent islands with dimensions in the 2–4 nm range. A luminescence band in the 1.3 μm region found exclusively for samples with such InAs…
The Weiss mean-field theory is applied to finite systems with unrestricted sizes, yielding a partition function for supercooled liquids. Finite-size effects broaden the transition and induce a Curie-Weiss--like energy reduction which provides an explanation for the Vogel-Tamman-Fulcher law. Because the energy reductio…
A blue emission powder phosphor Sr2CeO4 for field emission displays was prepared using a chemical coprecipitation technique, which is most suitable for large-scale production. The powders were fired at different temperatures to optimize the properties. Firing the powder at 1200 °C for 2 h gave the highest luminescence…
We report significant intergrain magnetoresistance (IMR) in polycrystalline double perovskites of SrFe1−x(Mo or Re)xO3 at room temperature. Systematics of the temperature dependence of IMR indicates that the observed large room-temperature IMR in SrFe1/2Mo1/2O3 originates from the ferrimagnetic nature of insulating gr…
A mesoscopic model of a diblock copolymer is used to study the stability of a lamellar structure under a uniform shear flow. We first obtain the nonlinear lamellar solutions under both steady and oscillatory shear flows. Regions of existence of these solutions are determined as a function of the parameters of the mode…
Carbon nanotubes prepared by catalytic (CO) disproportionation were studied using TEM, XRD, UPS, XPS, and optical spectroscopies. In comparison with graphite, the carbon nanotubes show greater interplanar distance, smaller work function, steeper Fermi edge, negative core-level shift, and stronger plasma excitation. Th…
Herein we establish a relationship between controlled nanoscale surface interactions and subsequent macromolecular ordering. Striped surfaces of oxide and metal are generated over large areas, where the stripe width is comparable to the size of a polymer molecule. Homopolymers are found to anisotropically dewet such s…
High-energy electron irradiation in ZnO produces shallow donors at about ${E}_{C}\ensuremath{-}30\mathrm{meV}$. Because the production rate is much higher for Zn-face (0001) than O-face $(000\overline{1})$ irradiation, the donor is identified as a Zn-sublattice defect, most likely the interstitial ${\mathrm{Zn}}_{I}$…
Current-voltage characteristics were studied for polypyrrole films contacted with different electrolytes in aqueous form and complex polymer solid electrolytes. Cyclic voltammograms for the conducting polymer in aqueous medium exhibited the typical oxidation and reduction peaks, whereas for solid polymer electrolytes,…
Ring-opening polymerization of lactone and lactide have been initiated with rare earth organoacid compounds, such as lanthanum acetate in bulk. The polymerization mechanism is in agreement with the “nonionic–coordination–insertion” mechanism, which involves the selective cleavage of the acyl–oxygen bond of the monomer…
Polypyrrole coatings have been successfully formed on steel from aqueous oxalic acid-pyrrole solutions by electrochemical polymerization. Formation of the coatings was found to be dependent on the pH of the reaction solution and the applied current. In acidic medium, the formation of polypyrrole was characterized by a…
A-two stage culture method of hydrogen-oxidizing bacterium, Alcaligenes eutrophus, is used to produce poly-D-3-hydroxybutyrate, P(3HB) from CO2, O2, and H2 without using a very high oxygen transfer rate while maintaining the O2 concentration in gas phase below 6.9 (v/v)% to prevent detonation of the gas mixture. The t…
Polymerization-induced phase separation (PIPS) to produce PDLCs is usually carried out in the one-phase regime to obtain the final dispersion. This PIPS process results in significant residual liquid crystal solubility in the matrix. We investigate a new method to reduce liquid crystal solubility by cooling a homogene…
A systematic study of the structural properties and electronic structure of six phases of C 3 N 4 is presented. The phases under study are the β, α, cubic, pseudocubic and two graphitic with different space group. The structural analysis shows that only in β and graphitic phases the N atoms behave in a pure sp 2 confi…
In recent publications it was pointed out that there is a correlation between the observed values of the solubility of proteins in aqueous solutions and the second virial coefficient of the solution. In this paper we give a theoretical explanation of this relation. The derived theoretical expression describes the expe…
We discuss a new class of phenomena based on strong interaction between magnetic superstructures and vortices in superconductors in combined heterogeneous structures. An inhomogeneous magnetization can pin vortices or create them spontaneously changing drastically properties of the superconductor. On the other hand, t…
We present results of ab initio theoretical investigations of the excitation spectra of correlated electrons in metals (Al, K, and Li) and their interplay with inelastic scattering experiments. We resolve various anomalies contained in the data, which were originally viewed as signatures of strong dynamical electronic…
X-ray photoelectron spectroscopy (XPS) analysis of four Cu/SiO 2 catalyst systems of different particle sizes of CuO on the surface showed variation in the relative peak area intensities of the shake-up lines to main core levels of the Cu 2p orbitals. These differences were attributed to various degrees of XPS-induced…
The molecular structure of the polyethylene oxide (PEO) molecular complexes with resorcinol (RES) and 2-methylresorcinol (two allotropic forms α-2MR and β-2MR) have been solved and refined by an X-ray diffraction technique (the “whole-pattern method”). The space group is Pna 2 1 for RES ( a = 10.54 Å, b = 10.18 Å, c =…
An analytical study is presented for the thermocapillary migration of a fluid sphere in a constant applied temperature gradient perpendicular to a planar surface. The Peclet and Reynolds numbers are assumed to be small, so that the appropriate energy and momentum equations of the fluids inside and outside the droplet…