Materials Literature
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[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…
Neutron powder diffraction measurements on ${\mathrm{Ca}}_{2}{\mathrm{FeReO}}_{6}$ reveal that this double perovskite orders ferrimagnetically and shows anomalous lattice parameter behavior below ${T}_{C}=521\mathrm{K}.$ Below $\ensuremath{\sim}300\mathrm{K}$ and $\ensuremath{\sim}160\mathrm{K}$ we observe that the hi…
Recent experiments have identified three-layer and four-layer distorted helical structures in the smectic liquid-crystal phases Sm C*(FI1) and Sm C*(FI2), respectively. However, no theories have explained the existence of all these phases. A discrete phenomenological model of the free-energy is analyzed and found to p…
HiPco single-walled carbon nanotubes (HPNTs) containing Fe were purified by a one-step process with HCl-washing (D-method) and a two-step process with HCl-washing after air oxidation (GD-method). The HPNT samples before and after purification were characterized using the N 2 adsorption at 77 K, thermogravimetric analy…
The random discontinuous fiber composite has uniform properties in all directions. The wetlay process is an efficient method to manufacture random discontinuous thermoplastic preform sheets that can be molded into random composite plaques in the hot-press. Investigations were done on the molding parameters that includ…
Charge transport and magnetic properties of films of polyaniline (PAN) doped with 10-camphorsulfonic acid and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) have been studied by conductivity, magnetic-susceptibility superconducting quantum interference device measurements, and 3-cm and 8-mm electron paramagnetic…
Dihydroxy-functionalized zwitterionic push−pull chromophores have been synthesized and incorporated into 3-glycidoxypropyltrimethoxysilane- and N -[(3-trimethoxysilyl)propyl]ethylenediamine-derived hybrid materials. The functionalization allowed the dye to form covalent bonds to the matrix network, reaching up to 5% m…
Mass transfer in micro- and mesoporous materials is of crucial importance in their practical application for separation and catalysis, since the mobility of adsorbed molecules ultimately limits the rate of the overall processes. Diffusion, i.e. the irregular thermal motion of the molecules, is the dominating process.…
The oriented-gas model based on the additivity hypothesis is widely used in predicting the macroscopic nonlinear optical susceptibility of a molecular crystal from molecular (hyper)polarizability calculations. Here, we argue that the intermolecular hydrogen bond interactions will break the additivity relationship for…
Abstract Seven dicarboxylates of calcium were synthesized. The effect of dicarboxylate on the formation of β‐form polypropylene was investigated by X‐ray diffraction. Calcium pimelate, calcium suberate, calcium phthalate, and calcium terephthalate have been found to be an effective β‐nucleator. The K x values of the i…
Abstract The influence of a nonpigmenting β‐nucleating additive in the crystallization of isotactic polypropylene (iPP) is investigated by differential scanning calorimetry and X‐ray diffraction. It is found that this additive induces the formation of a very high level of the trigonal modification of iPP. The crystall…