Materials Literature
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Abstract Polymer networks showing different smectic polymorphism with either an interdigitated smectic A to undulated smectic A phase transformation or an interdigitated smectic A to double layer smectic C phase transformation are synthesized. Their orientation behavior in uniaxial mechanical fields is investigated by…
Three different sites of the ${\mathrm{Cr}}^{3+}$ ions in the fluoride perovskite ${\mathrm{KMgF}}_{3}$ have been identified by absorption, selective optical excitation, and time-resolved emission spectroscopy of the ${}^{4}{T}_{2}{\ensuremath{\leftrightarrow}}^{4}{A}_{2}$ transition. High-pressure measurements showin…
The synthesis of carboxyl-terminated poly(ethylene glycol adipate) (CTPA) and amine-terminated poly(amide sulfone) (ATPS) based on the CTPA and 4,4′-diaminodiphenyl sulfone (DDS) is described. The products were characterized by IR and 13C-NMR spectroscopic analysis, nonaqueous titration, viscosity measurement, and sol…
Time-resolved light scattering has been used to investigate phase-separation dynamics for off-critical mixtures of polybutadiene (PB) and polyisoprene (PI) with a well defined phase diagram. Percolation-to-cluster transition (PCT) occurs in the course of the phase separation process for an off-critical mixture of the…
Copolymers containing vinyl sugar units were synthesized by copolymerizing 2,3;4,5-di- O -isopropylidene-1-(4-vinylphenyl)- d -gluco( d -manno)pentitol ( 1 ) with styrene. Films and plates of the copolymers and blends were prepared by casting solutions on glass plates or by hot-pressing. Isopropylidene groups, the hyd…
Based upon the torus parametrization which was introduced recently, we present a recipe allowing for a complete analysis of the symmetry structure of quasiperiodic local isomorphism classes in one and two dimensions. A number of results is provided explicitly, including some widely used planar tiling classes with 8-,…
The rates of the reactions of ethyl radicals with HBr ( k 7 ) and with Br atoms ( k 8 ) have been measured in the temperature range 228−368 K at millitorr pressures using the very low pressure reactor (VLPR) technique. The Arrhenius function for the H atom abstraction reaction is found to be k 7 = (1.43 ± 0.06) × 10 -…
Dielectric spectroscopy is employed in two polystyrene−polyisoprene−polystyrene (SIS) triblock copolymers well below the order-to-disorder transition temperature and in the frequency range from 10 -2 to 10 6 Hz. Small angle X-ray scattering has shown the formation of lamellar structures with a long period of about 25…
Cobalt porphyrins in which Ru(NH3)52+ groups are coordinated to four cyanophenyl ligands pendant to the porphyrin ring act as catalysts for the electroreduction of O2 when adsorbed on the surface of graphite electrodes. The parent 4-cyanophenyl derivative catalyzes the four-electron reduction of O2 to H2O, but the 4-c…
The comparison of the results of calculations based on experimental data with those derived from a simple, two phase, elastic model proved the existence of a hard interphase in particulate-filled composites. Moreover, beside elastic properties, also other mechanical characteristics of the interphase, including yield s…
We have performed a neutron-diffraction study of the Laves hydride ${\mathrm{YMn}}_{2}{\mathrm{H}}_{4.3}$ to investigate the interplay between the atomic order in the hydrogen sublattice and the magnetic structure. We find that structural order in the H sublattice and antiferromagnetic order in the Mn sublattice have…
The reaction of a mixture of iron acetylacetonate and rare‐earth (Tm‐Lu) acetate in 1,4‐butanediol at 300°C yielded a novel phase of ReFeO 3 having a hexagonal crystal system (a0 = 6.06, c 0 = 11.74 A) together with small amounts of Fe 3 O 4 and/or the garnet phase. The particle size of the product distributed in a na…
The photosynthetic bacterium Rhodobacter capsulatus can grow with short- to long-chain fatty acids as the sole carbon source (R. G. Kranz, K. K. Gabbert, T. A. Locke, and M. T. Madigan, Appl. Environ. Microbiol. 63:3003-3009, 1997). Concomitant with growth on fatty acids is the production to high levels of the polyest…
The Mars and Van Krevelen model can be applied to all the steps of the oxidation of isobutane by oxygen over a heteropolyanion catalyst. The reaction scheme includes both direct (from isobutane) and indirect (via methacrolein) methacrylic acid production. The determinant multiresponse criterion has proved very efficie…
Aluminum specimens coated with porous anodic oxide films were dipped in solutions containing , or ions and heated in air mainly at 400°C to deposit Ti, Nb, or Ta oxide on the inner walls of pores. After 0 to 7 cycles of the dipping and heating process, the specimens were reanodized in a neutral borate solution to fill…
Abstract The Fe 3+ substituted for Al 3+ at the 2 octahedral positions is one of the most common impurities in the kaolinite structure detected by electron paramagnetic resonance (EPR). Evidence has been provided for a relationship between the shape of EPR spectra for structural Fe and the structural disorder in kaoli…
Cu/Mg/Al catalysts obtained by controlled calcination of hydrotalcite-type (HT) anionic clays may be new interesting and cheap catalysts for the selective catalytic reduction (SCR) of NO by NH 3 . In this paper the ammonia adsorption and oxidation on Cu x Mg 0.710 - x Al 0.290 catalysts ( x = 0.022, 0.046, and 0.072,…
We found three smectic phases, SmX1, SmX2 and SmX3, in achiral compounds with banana shape. The SmX1 phase has a biaxial single molecular layer, along which polarization exists. The polarization precesses along the layer normal, and is aligned by applying an electric field. The spontaneous polarization is about 60 nC/…
Thermotropic liquid-crystalline behavior of phosphonium salts, which are structurally simple amphiphiles with positively-charged phosphorus atoms and without rigid cores, was evaluated by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffractometry. The phosphonium salts were found to sho…
Surface modification with hydrophilic polymers has been beneficial in improving blood compatibility of biomaterials. Formation of dense and tightly-bonded surface layers may prevent plasma protein adsorption owing to steric repulsion. General conditions for formation of layers, protecting blood components from direct…