Materials Literature
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Zn in GaN forms an efficient radiative center and acts as a deep acceptor which can make the crystal insulating. Four different Zn-related centers have been by now identified, leading to light emission in the range between 1.8 eV and 2.9 eV. We present a first-principles investigation total energy and electronic struc…
The formation energy of a solid surface can be extracted from slab calculations if the bulk energy per atom is known. It has been pointed out previously that the resulting surface energy will diverge with slab thickness if the bulk energy is in error, in the context of calculations which used different methods to stud…
Impurity levels and formation energies of acceptors in wurtzite GaN are predicted ab initio. Be_Ga is found to be the shallow (thermal ionization energy $\sim$ 0.06 eV); $Mg_{Ga}$ and $Zn_{Ga}$ are mid-deep acceptors (0.23 eV and 0.33 eV respectively); $Ca_{Ga}$ and $Cd_{Ga}$ are deep acceptors ($\sim$0.65 eV); $Si_N$…
The traditional magnetic storage mechanisms (both analog and digital) apply an external field signal H(t) to a hysteretic magnetic material, and read the remanent magnetization M(t), which is (roughly) proportional to H(t). We propose a new analog method of recovering the signal from the magnetic material, making use…
A novel procedure for calculating magnetic susceptibilities and nuclear magnetic shieldings in molecules is outlined, based on formal annihilation of transverse paramagnetic contribution to quantum mechanical current density induced within the electron cloud by an external homogeneous, static magnetic field. Within th…
This article describes the synthesis of biodegradable polyphosphazenes. The rate of degradation can be varied in a controllable manner by the introduction of hydrolysis-sensitive amino acid ester side groups or by blending of polymers. Biodegradable polyphosphazenes can be used for the preparation of drug-containing i…
Microporous polypropylene fibers were prepared by stretching polypropylene fibers containing CaCO3 filler. The properties of the resultant fibers are controllable by adjusting the filler content and the stretching ratio. Also, it is elucidated that the fibers have a fine texture of polypropylene fibrils, in which the…
This paper describes a vision-based system that monitors the yarn density of woven fabrics on-line. The system is described in terms of its two principal modules, namely, the image acquisition and the image analysis subsystems. The image acquisition subsystem is implemented with standard components on a low-cost perso…
In this article, two kinds of perfluoropolyether (PFPE) with different terminal groups were investigated using thermogravimetric analysis (TGA), infrared (IR) spectroscopy, gel permeation chromatography (GPC), and gas chromatography/gas mass spectrum (GC/MS) analysis. PFPEs with a hydroxyl or carboxylic acid terminal…
The morphology of the microcellular ethylene–propylene–diene terpolymer (EPDM) vulcanizes of both an unfilled and filled compound was studied from SEM photomicrographs. Carbon blacks adversely affect the average cell size, maximum cell size, and cell density. Enclosed gas pressure in a closed cell increases the relati…
Low-density polyethylene/ethylene–vinyl acetate copolymer (LDPE/EVA) blend was irradiated by γ-ray and then expanded by heat as a foamed material. The EVA content in the LDPE/EVA blend was benefited to form a gel. The gel fraction values of LDPE/EVA blend with 30% EVA content were higher than those of other blends in…
High-performance tetrafunctional epoxy resins were synthesized by reacting a suitable tetraphenols which were obtained by the condensation of appropriate dialdehyde with phenol followed by epoxidation with a halohydrin. The structure of the synthesized tetraphenols was confirmed by infrared (IR), mass spectra (MS), an…
A novel process has been developed to toughen phenolic resin by polyurethane for fiber-reinforced pultruded composites. The mechanical properties of the composites (tensile strength, flexural strength, and notched Izod impact strength) approach maximum values at 10 wt% of the blocked polyurethane content. The fabricat…
Polyaniline (PAn), an important conducting polymer, was synthesized chemically. Percentage crystallinity of PAn on doping with various dopants (viz., hydrochloric acid, formic acid, iodine, methylene blue) has been investigated using wide-angle X-ray diffraction analysis. It is observed that percentage crystallinity (…
The compatibility for binary blends of isotactic polypropylene with rubbery ethylene-α-olefin copolymers having various α-olefin contents was investigated by means of differential scanning calorimetry, X-ray analysis, transmission electron microscopy, and dynamic mechanical analysis. It was found that “α-olefin rich”…
A first-principles atomic orbital-based electronic structure method is used to investigate the low index surfaces of rutile Titanium Dioxide. The method is relatively cheap in computational terms, making it attractive for the study of oxide surfaces, many of which undergo large reconstructions, and may be governed by…
A Supramolecular Approach to Light Harvesting and Sensitization of Wide--Bandgap Semiconductors: Antenna Effects and Charge Separation (C. Bignozzi, et al.). Langmuir--Blodgett Films of Transition Metal Complexes (M DeArmond & G. Fried). Layered Metal Phosphonates as Potential Materials for the Design and Construction…
The structure of CO adsorbates on the Rh(110) surface is studied at full coverage using first-principles techniques. The relative energies of different adsorbate geometries are determined by means of accurate structure optimizations. In agreement with experiments, we find that a p2mg(2x1) 2CO structure is the most sta…
The polarizing interference microscope was used to study the variation of the principal optical parameters of annealed nylon 6 Fibres at 160 ± 1°C. The resulting data were used to calculate optical orientation function, the angle of orientation and the specific refractivity of the isotropic dielectric over all the ann…
(1996). Using Si/Al ratios in suspended matter and sediments as an indicator of diatom productivity changes. GFF: Vol. 118, No. sup004, pp. 89-90.