Materials Literature
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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…
Scattering states with LEED asymptotics are calculated for a general non-muffin tin potential, as e.g. for a pseudopotential with a suitable barrier and image potential part. The latter applies especially to the case of low lying conduction bands. The wave function is described with a reciprocal lattice representation…
We demonstrate that the reorientation transition from out-of-plane to in-plane magnetization with decreasing temperature as observed experimentally in Ni-films on Cu(001) can be explained on a microscopic basis. Using a combination of mean field theory and perturbation theory, we derive an analytic expression for the…
Muon spin rotation ( $\ensuremath{\mu}\mathrm{SR}$) measurements have been performed on the organic superconductor $\ensuremath{\kappa}\ensuremath{-}(\mathrm{BEDT}\ensuremath{-}\mathrm{TTF}{)}_{2}\mathrm{Cu}(\mathrm{SCN}{)}_{2}$ in order to investigate its exotic vortex behavior. Previously unobserved features of the…
We report on the thin films of solid–solution material (1−x)SrBi2Ta2O9−xBi3Ti(Ta1−yNby)O9 fabricated by a modified metalorganic solution deposition technique for ferroelectric random access memory devices. Using the modified technique, it was possible to obtain the pyrochlore free crystalline thin films at an annealin…
Studies of the influence of defect distributions and mobility on ferroelectric phase transformations in lead zirconate titanate have been performed by transmission electron microscopy, high resolution electron microscopy, polarization switching measurements, and dielectric spectroscopy. Investigations focused on La3+…
We report on a remarkably large second-harmonic generation (SHG) in a germanosilicate glass (15.7 GeO2–84.3 SiO2 in mol %), which was induced by poling while the sample was irradiated with the ArF laser at the wavelength of 193 nm. The SHG coefficient, d, thus induced was measured at various poling electric-field stre…
Guided-mode resonance optical filters are made from thin-film structures which consist of azopolymer films deposited on top of slab waveguides. Surface relief gratings can be optically induced on the azopolymer films. The transmission and reflection spectra as a function of the angle of incidence of the probe beam exh…