Materials Literature
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SiO 2 films containing Si nanocrystals (nc-Si) and Er were prepared and their photoluminescence (PL) properties were studied. The samples exhibited luminescence peaks at 0.81 and 1.54 μm, which could be assigned to the electron-hole recombination in nc-Si and the intra-4f transition in Er3+, respectively. Correlation…
A recently developed dynamical mean-field theory, in the iterated perturbation theory approximation, was used as a basis for the construction of a `first-principles' calculation scheme for investigating the electronic structure of strongly correlated electron systems. This scheme is based on the local density approxim…
For ultrasonic transducers, piezoelectric ceramics offer a range of dielectric constants (K/spl sim/1000-5000), large piezoelectric coefficients (d/sub ij//spl sim/200-700 pC/N), and high electromechanical coupling (k/sub t//spl sime/50%, k/sub 33//spl sime/75%). For several decades, the material of choice has been po…
1.: Introduction. 2.: Molecular field approximation. 3.: The Heisenberg Hamiltonian. 4.: Magnetization vs. temperature. 5.: Anisotropy and time effects. 6.: Another energy term. 7.: Basic micromagnetics. 8.: Energy minimization. 9.: The nucleation problem. 10.: Analytic micromagnetics. 11.: Numerical micromagnetics. R…
In this text, the authors offer an account of thermoluminescence (TL) and other thermally stimulated phenomena. Although most recent experimental results of TL in different materials are described in some detail, the emphasis is on general processes, and the approach is more theoretical.Thus , the details of the possi…
<h3></h3> It has been estimated that malnutrition affects 50% of hospice patients. Nutritional assessment and support is vital in palliative care, since inadequate hydration and nutrition results in skin and muscle wasting, vulnerability to the development of pressure ulcers, and susceptibility to infection. <h3>Metho…
high-excitation-energy approach to fibre grating inscription David N Nikogosyan - Effect of high-power ultraviolet laser radiation on nucleic acid bases D N Nikogosyan - Method for orientation of uniaxial nonlinear single crystals Yu V Voroshilov and D N Nikogosyan -This content was downloaded from IP address 149.
The diatom flora from Neogene lake basins in South Bulgaria is summarized and analysed. It consists of 627 species, varieties and forms, wich are distributed as follows: 459 species, 141 varieties and 27 forms (with uncleared nomenclature are 32 species). The species are referred to 51 genera, 23 families, 7 orders an…
A detailed mathematical model is developed to describe the operation of batch-modified SAN [styrene (ST)/acrylonitrile (AN)/α-methylstyrene (AMS)] terpolymerization reactors. The model is validated by comparing simulation results with published and plant experimental data. Optimal temperature policies and initiator fe…
The action of two complementary chain extenders is studied in model systems as well as in poly(ethylene terephthalate) (PET) and nylon–6. Chain extenders are low molecular weight compounds that can be used to increase the molecular weight of polymers in a short time. The reaction must preferably be fast enough to exec…
Thin film of poly (5-isopropylidenecyclo-1,4-vinylene-2,3-dicarboxylicacidamide-s-methyl hydrazinecarbodithioate) (II) (Scheme 1) of 5 μm thickness was prepared. The dielectric properties of the prepared sample were studied as a function of frequency and temperature, and the results were analyzed by the Cole–Cole meth…
We present Monte Carlo data for a linear chain with excluded volume subjected to a uniform stretching. Simulation of long chains (up to 6000 beads) at high stretching allows us to observe the signature of tensile blobs as a crossover in the scaling behavior of the chain scattering function for wave vectors perpendicul…
We revisit the hard-spheres lattice gas model in the spherical approximation proposed by Lebowitz and Percus (J. L. Lebowitz, J. K. Percus, Phys. Rev.{\ 144} (1966) 251). Although no disorder is present in the model, we find that the short-range dynamical restrictions in the model induce glassy behavior. We examine th…
Polymeric materials undergo dramatic changes in orientational order in response to dynamic processes, such as flow. Their rich cascade of dynamics presents opportunities to create and combine distinct alignments of polymeric nanostructures through processing. In situ rheo-optical measurements complemented by ex situ x…
The sophisticated use of self-organizing materials, which include liquid crystals, block copolymers, hydrogen- and π-bonded complexes, and many natural polymers, may hold the key to developing new structures and devices in many advanced technology industries. Synthetic materials are usually designed with only one stru…
Organic molecules can alter inorganic microstructures, offering a very powerful tool for the design of novel materials. In biological systems, this tool is often used to create microstructures in which the organic manipulators are a minority component. Three groups of materials-biomaterials, ceramics, and semiconducto…
Multilayer films of organic compounds on solid surfaces have been studied for more than 60 years because they allow fabrication of multicomposite molecular assemblies of tailored architecture. However, both the Langmuir-Blodgett technique and chemisorption from solution can be used only with certain classes of molecul…
A mechanistic study of the in situ immobilization of a toxic metal species in a high-temperature environment using gas phase sorbent precursors is described. Planar laser-based imaging measurements of fluorescence and particle scattering have been obtained to study the interaction of lead with silicon species in high-…
The dynamic behavior of gaseous nicotine was studied in a 20-m 3 stainless steel chamber. Nicotine (10−40 mg) was emitted into the sealed chamber by cigarette combustion or flash evaporation of pure liquid. After 3 h, during which time the airborne concentration was monitored, the chamber was ventilated for 2 h and th…
Angle-resolved ultraviolet photoemission spectra are interpreted by combining the energetics and spatial properties of the contributing states. One-step calculations are in excellent agreement with new azimuthal experimental data for GaAs(110). Strong variations caused by the dispersion of the surface bands permit an…