Materials Literature
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Abstract We give here a model for the pressure dependent, biaxial mechanical behavior of glassy polymers based on the thermally activated growth of deformation zones (Somigliana dislocation loops). The Coulomb criterion of plasticity, σ c = S − m σ n , is found as the critical threshold needed to propagate Somigliana…
A variety of plasma etching chemistries were examined for patterning NiMnSb Heusler alloy thin films and associated barrier layers. Chemistries based on , and were all found to provide faster etch rates than pure Ar sputtering. In all cases the etch rates were strongly dependent on both the ion flux and ion energy. Se…
Two new layered compounds, Pb2BaCuFeO5X (X = Cl, Br), have been prepared by a solid-state reaction. The structure of these compounds is an intergrowth of a defective perovskite BaCuFeO5 block unit and a cesium chloride type Pb2X layer. The structure is related to that of the mineral hematophanite by removing the centr…
Mineral crystals with specific surface texture have been grown by a templating mechanism from a lyotropic liquid-crystalline phase. This experimental system is important in understanding mineralization in ordered organic media, a phenomenon of importance in biology and possibly in biomaterials technology as well. The…
A simplified method for planarizing liquid-crystal-on-silicon (LCOS) backplanes is presented. The method relies on the planarizing capability of spin-cast benzocyclobutene (BCB) polymeric resin. BCB planarization shows a sixfold reduction in step height on the surface of a typical LCOS backplane. Contact with the unde…
Nanoporous Si layers have been investigated by photoacoustic (PA) spectroscopy. The optical absorption spectra for porous Si on p-type Si substrates were obtained in the region of 300 to 1500 nm. The absorptivity became remarkable at 600 nm and increased drastically up to the saturation value while the wavelength decr…
Article SYNTHESIS, CHARACTERIZATION AND THERMAL BEHAVIOUR OF CALCIUM AND STRONTIUM 2, 2, 6, 6-TETRAMETHYL-3,5-HEPTANEDIONATE COMPLEXES. CRYSTAL STRUCTURE OF [Sr(μ, η2-thd)(η2-thd)(η2-MeOC2H4OH)]2 was published on October 1, 1997 in the journal Main Group Metal Chemistry (volume 20, issue 10).
Pigeon liver malic enzyme has an N-terminal amino acid sequence of Met-Lys-Lys-Gly-Tyr-Glu-. In this work, various mutants of the enzyme with individual or combinational deletion (delta) or substitution at these amino acids were constructed and functionally expressed in Escherichia coli cells. A major protein band cor…
The energy distribution of the electrons backscattered in the direction of the surface normal of polycrystalline silver samples was studied using reflected electron energy loss spectroscopy (REELS) at 200 eV and 2 keV primary beam energies. For modeling the electron scattering processes, the Monte Carlo simulation tec…
The influence of poly(octadecyl acrylate) (PODA), which is a comb-like polymer with ethylenic side chains, on the crystallization and morphological behavior of high-density polyethylene (HDPE) in a binary blend was investigated. The studied parameters were the cooling rate, degree of crystallinity, spherulite size, an…
In this work, confirmation of the molecular formula and investigation of the structural stability of the prepared various types of heteropoly acids and their salts by TGA are reported. Specific surface areas of the samples were determined by the BET-single point N2 adsorption method. Scanning electron microscopy (SEM)…
A new design philosophy was tried out on a carbide-reinforced tool for hot working of stainless steel. The carbide particle in the micro structure of the new tool was selected so as to meet the relatively large optimum size. Attention has been focused, in the conventional tool, on the enlargement of the area fraction…
The electronic structures of the layered ternary tellurides Ta 3 Pd 3 Te 14 and Ta 4 Pd 3 Te 16 are examined. It is found that the presence of bicapped trigonal prismatic chains with extensive Te···Te interactions results in very wide tellurium-based bands along the direction of the chains. The local octahedral coordi…
This paper deals with optimization of a class of linear time-varying dynamic systems with n states and m control inputs commanded to move between two fixed states in a prescribed final time. Using a conventional procedure with Lagrange multipliers, it is well known that the optimal solution must satisfy 2n first-order…
In the electron-beam fabrication of interferogram-type diffractive elements, such as diffractive lenses, continuous fringes are often approximated by polygons to reduce the data volume. Local wave-front errors are then generated that scatter light and give rise to background noise. A roughness parameter beta is introd…
A thin, one-dimensional, gradient-index slab lens with a parabolic profile was designed and fabricated in fluorine-doped silica by use of plasma-enhanced chemical vapor deposition in a Helicon plasma reactor. The refractive-index profile of the fabricated lens was determined by the application of an inversion techniqu…
Pb- and Te-doped borosilicate glasses are transformed by appropriate heat treatment into a composite material consisting of a vitreous matrix in which semiconductor PbTe nanocrystals are embedded. This composite exhibits interesting non-linear optical properties in the infrared region, in the range 10–20 000 Å. The sh…
We analyze conformational stereoisomerism in the sterically hindered 4a,4b-dihydrophenanthrenes of C 2 symmetry. In these labile photointermediates, steric hindrance brought about by disubstitution at the 4 and 5 positions or by benzoannelation at the [c] and [g] bonds allows observation of two interconvertible interm…
We have demonstrated the evaluation of nonlinear optical properties and the determination of the molecular orientation of the mixed crystals of p -nitroaniline ( p -NA) and N -ethyl-4-nitroaniline (NENA) in powder form. Although neither material shows second-order nonlinearity due to the crystalline structure, the obt…
In order to develop an on-line system to characterize fabric bending rigidity, four potential loop shapes are proposed. Loop shapes are chosen such that they can be formed under dynamic conditions. Results from theoretical models of these loops show the nature of the response of loop shapes to varying fabric bending b…