Materials Literature
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We investigate the characteristics of electromagnetic wave propagation in uniaxially anisotropic left-handed media. We discuss mainly under what conditions anomalous reflection or refraction shall occur at the interface when propagating waves pass from one isotropic regular medium into another uniaxially anistotropic…
Abstract The crystallization properties of three regioregular poly(3‐alkyl thiophene)s (P3ATs) are studied: poly(3‐hexyl thiophene) (P3HT), poly(3‐octyl thiophene) (P3OT), and poly(3‐dodecyl thiophene) (P3DDT). The morphology of the isothermally crystallized samples is a whisker type. The values of the enthalpy of fus…
The fluorination of purified HiPco single-wall carbon nanotubes to a stoichiometry CF x ( x ⩽ 0.2) followed by pyrolysis of the partially fluorinated nanotubes up to 1000 °C was found to have “cut” the nanotubes to a range of short lengths (average <50 nm). The pyrolysis process was monitored in-situ with TGA-FTIR. Th…
Abstract Three solvents, that is, acetone, acetic acid, and dimethylacetamide (DMAc), with a range of solubility parameter δ, surface tension γ, viscosity η and boiling temperature were used to generate mixtures for electrospinning cellulose acetate (CA) (degree of substitution, DS = 2.45). Although none of these solv…
Carbon nanotubes have been the subject of considerable attention because of their exceptional physical and mechanical properties. These properties observed at the nanoscale have motivated researchers to utilize carbon nanotubes as reinforcement in composite materials. In this research, a micro-scale twin-screw extrude…
Synthesis of carbon nanotubes by chemical vapor deposition over patterned catalyst arrays leads to nanotubes grown from specific sites on surfaces. The growth directions of the nanotubes can be controlled by van der Waals self-assembly forces and applied electric fields. The patterned growth approach is feasible with…
The synthesis of the fluorine-substituted stannasiloxane complex cyclo-Ph 2 Si(OSnt-Bu 2 ) 2 O· t -Bu 2 SnF 2 ( 7 ) is reported, and its molecular structure has been determined by single-crystal X-ray diffraction analysis.
The synthesis of the fluorine-substituted stannasiloxane complex cyclo-Ph2Si(OSnt-Bu2)2O·t-Bu2SnF2 (7) is reported, and its molecular structure has been determined by single-crystal X-ray diffraction analysis.
Solutions of 4-methylphenylurethane of cellulose in N -vinyl pyrrolidinone have been investigated, and a cholesteric mesophase was found above a concentration of 35 wt % of polymer. The selective reflection of light from the cholesteric solutions lies in the visible region of the spectrum and moves from blue toward re…
We evaluate, by means of variational calculations, the bound state energy ${E}_{B}$ of a pair of charges located on the surface of a cylinder, interacting via Coulomb potential $\ensuremath{-}{e}^{2}/r.$ The trial wave function involves three variational parameters. ${E}_{B}$ is obtained as a function of the reduced c…
[structure: see text] An o-allenyl-p-methoxyphenol intermediate (Int) was for the first time proved to be involved in the photochromic reaction of 2,2-di(4-fluorophenyl)-6-methoxy-2H-1-chromene (FC). Transoid-cis (TC) and transoid-trans (TT) photomerocyanines and the intermediate Int are generated by UV irradiation of…
A formalism based on Yeh’s 4 × 4 matrix algebra is developed to model reflectance and transmittance spectra of randomly oriented polycrystalline materials (sintered ceramics or glass ceramics) with arbitrary crystal symmetry provided that the crystallites are larger than the resolution limit of light. It may be applic…
The CO 2 reforming of methane was studied over Pt supported on Al 2 O 3, ZrO 2, and x % ZrO 2 /Al 2 O 3 (1 ≤ x ≤ 20 wt %). The Pt/Al 2 O 3 deactivated very quickly during 20 h onstream at 1073 K and a CH 4 /CO 2 ratio of 1:1, while the catalysts with a ZrO 2 content above 5 wt % presented improved stability during 60…
The photoinduced electron transfer (ET) in five structurally different phytochlorin-fullerene dyads was studied in polar and nonpolar solvents using femtosecond fluorescence up-conversion and pump−probe transient-absorption techniques. Small changes in the structures of the dyads result in considerable changes in the…
We report experimental evidence for the stress-induced tetragonal symmetry of the paraelectric phase in heteroepitaxial $({\mathrm{Ba}}_{0.7}{\mathrm{Sr}}_{0.3}){\mathrm{TiO}}_{3}$ thin film deposited on the (001)MgO substrate. Our Raman and x-ray-diffraction data evidently show that symmetry of the paraelectric phase…
The synthesis and mesomorphic properties of a new series of five-ring esters composed of banana-shaped molecules are reported. The homologues containing n-dodecyloxy, n-tetradecyloxy and n-hexadecyloxy terminal chains exhibit a smectic phase while that with an n-octadecyloxy chain shows a two-dimensional structure. Th…
The influence of γ-irradiation on the positron annihilation lifetime spectra in chalcogenide vitreous semiconductors of As-Ge-S system has been analysed. The correlations between lifetime data, structural features and chemical compositions of glasses have been discussed. The observed lifetime components are connected…
Clinically available synthetic ePTFE vascular grafts frequently fail when used for small-diameter arterial substitution. The lower long-term patency of ePTFE grafts is due mainly to thrombogenicity and poor healing. We developed a new small-diameter (1.5-mm) ePTFE vascular prosthesis coated with polyamino-acid urethan…
Abstract The use of biodegradable polymer films for mulching is a topic of great interest both from the environmental point of view and for the intrinsic properties that the above films, when appropriately designed, might have. In the present article we report on a synthetic approach that, starting from existing biode…
Abstract In this article, we discuss the radiation effects of high‐density polyethylene (HDPE)/ethylene–vinyl acetate (EVA) copolymer blends. In comparison with the low‐density polyethylene/EVA blends, the EVA content in the HDPE/EVA blends had a lower enhancement effect on radiation crosslinking by γ‐ray irradiation…