Materials Literature
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Glass temperature depression, measured by means of dynamic mechanical analysis, of elastomers blended together with isotactic, syndiotactic, and atactic poly(propene), PP, was detected for the first time. Two-phase melt blends consisting of PP and elastomers such as polystyrene- block -poly(ethene- co -1-butene)- bloc…
The combustion performance of polyamide 6 (PA 6) and poly(butylene terephthalate) (PBT), both fire retarded by phosphorus oxynitride (PON), was studied by oxygen index (OI) and Underwriters Laboratory UL94 tests. It was shown that either PON alone or in combination with different co-additives is efficient in PA 6 and…
We study theoretically convection phenomena in a laterally extended planar nematic layer driven by an ac-electric field (electroconvection in the conduction regime) or by a thermal gradient (thermoconvection). We use an order-parameter approach and demonstrate that the sequence of bifurcations found experimentally or…
Only the second octahedral, paramagnetic copper(III) complex (S=1) has now been synthesized and characterized. Six thiolato bridging ligands in the heterotrinuclear species [LCoIIICuIIICoIIIL](ClO4)3⋅2 Me2CO (L=1,4,7-tris(4-tert-butyl-2-sulfidobenzyl)-1,4,7-triazacyclononane) stabilize this rare electron configuration…
In this study the CH4 dissociation probability on Ru(0001) is found for various translational and vibrational energies. The absolute sticking values are determined from King and Wells experiments and carbon uptake curves. The carbon amount is determined from the recombination signal of carbon with oxygen obtained afte…
The structure of Bacillus amyloliquefaciens ribonuclease (barnase), an extracellular 110-residue enzyme initially solved at 2.0 A resolution, has been refined at 1.5 A using synchrotron radiation and an imaging-plate scanner. Refinement with anisotropic atomic displacement parameters resulted in increased accuracy of…
We consider a new concept of weak solutions to the phase-field equations with a small parameter ε characterizing the length of interaction. For the standard situation of a single free interface, this concept (in contrast with the common one) leads to the well-known Stefan–Gibbs–Thomson problem as ε→0. For the case of…
We consider the steady-state distribution of ionic charges in a nematic sample of slab shape, whose limiting surfaces are supposed to adsorb positive ions. Our analysis allows the calculation of the electrical potential at the surfaces and in the bulk, and of the chemical potential versus the thickness of the sample d…
The viscosities of hydrous melts (0.65 to 2.8 wt% H 2 O) with quartzofeldspathic compositions corresponding to Ab, Ab 74 Qz 26 , and Ab 48 Qz 52 (mole proportions calculated on the basis of eight oxygen atoms; Ab = NaAlSi 3 O 8 , Qz = Si 4 O 8 ) have been determined between 980 and 1375 °C at pressures between 190 and…
The development of mild chemistry routes to novel oxides—instead of the traditional ceramic method—is an active area of research with an additional aim of finding new electrolytes. The authors report the low temperature hydrothermal synthesis and the property characterization of a wide range of nanocrystalline solutio…
We calculate the dynamic order parameter and dielectric susceptibility for the relaxor ferroelectrics like PbMg1/3Nb2/3O3, PbSc1/2Ta1/2O3 and Pb1−xLaxZryTi1−yO3. Calculations of temperature and frequency dependence of dielectric susceptibility show the existence of low- and high-temperature group of maxima obeyed to V…
Abstract The preparation and characterization of Ln(III) complexes (Ln = Eu, Gd, Tb, Er, Tm, Lu) of heptadentate (N4O3) ligand trensal, tris[2-(salicylideneamino)ethyl]amine (H3L1), have been studied. The molecular structures of [LnL1] were determined by X-ray structural analysis ; these are heptadentate complexes in…
The enzymatic ring-opening polymerization of a 6-membered cyclic depsipeptide, 3(S)-isopropylmorpholine-2,5-dione in the bulk, was investigated by using lipases as catalysts at 100 and 130°C. Unchanged monomer was recovered in the absence of the enzyme or using an inactivated enzyme, indicating that the present polyme…
Recent NMR experiments on supercooled toluene and glycerol by Hinze and B\"ohmer show that small rotation angles dominate with only a few large molecular rotations. These results are here interpreted by assuming that viscous liquids are solidlike on short length scales. A characteristic length, the ``solidity length,'…
The effects of axial ligands in Sn ( IV )-substituted 5,10,15,20-tetrakis [4-(carboethoxymethyleneoxy)phenyl]porphyrin and divalent transition metal substitution in 5,10,15,20-tetraphenylporphyrin on the second molecular hyperpolarizability (γ) at 802 nm were studied using the Z-scan technique. A significant increase…
Brillouin light scattering is used for studying the spectrum of density fluctuations of the glass-forming epoxy resin diglycidyl ether of bisphenol-$A.$ Spectra at different temperatures ranging from the glassy to the liquid phase are obtained from a direct subtraction of depolarized from polarized spectra. In additio…
A method for the joining of silicon carbide using a cordierite glass‐ceramic has been developed. Cordierite, with glass‐ceramic processing, remains amorphous and wets the SiC substrate to form a strong bond when rapidly fired. Subsequent heat treatment crystallizes a multiphase interlayer with a matching bulk thermal…
In planar geometrical optics, the rays normal to a periodically undulating wavefront curve W generate caustic lines that begin with cusps and recede to infinity in pairs; therefore these caustics are not periodic in the propagation distance z. On the other hand, in paraxial wave optics the phase diffraction grating co…
Within the framework of a free-energy landscape model for the relaxation in supercooled liquids the primary (\ensuremath{\alpha}) relaxation is modeled by transitions among different free-energy minima. The secondary (\ensuremath{\beta}) relaxation then corresponds to intraminima relaxation. We consider a simple model…
By computer simulation the anisotropic long-time translational self-diffusion coefficients are calculated in the nematic phase of colloidal hard spherocylinders exhibiting Brownian dynamics in a solvent. In particular, the two diffusion coefficients ${D}_{L}^{\ensuremath{\parallel}}$ and ${D}_{L}^{\ensuremath{\perp}},…