Materials Literature
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This paper reviews the nature of defects and optical centers in magnesium aluminate spinel. The identification of absorption and luminescence bands was used to investigate the influence of UV and electron irradiation on optical center formation. Crystals examined were nominally pure MgO‐ n Al 2 O 3 crystals with compo…
A refined expression for the secondary Bjerknes force between two spherical gas bubbles in a viscous incompressible fluid is derived, allowing for the dipole oscillations of the bubbles and acoustic streaming around them. The investigation is motivated by the fact that the existing theory [see, for example, E. A. Zabo…
This paper presents a review of leakage current (Lc) measurements on nonceramic insulators and material samples. It is divided into two parts: First, the field investigations of LC, include a development of LC measuring systems and how the on-line LC measurements correlate to the insulator performance as well as to th…
A conjugated polymer−redox polymer hybrid based on the complexation of poly[2-(2-pyridyl)bibenzimidazole] with bis(2,2‘-bipyridyl)Ru 2+ has been prepared to take advantage of electronic communication between metal centers through the conjugated backbone. The existence of such communication is confirmed by the observat…
Kinetics of the development of a conversion coating from a stannate bath on commercial purity magnesium (Mgcomm), magnesium-based alloys ZC71 and WE43, and a metal matrix composite (MMC), comprising a ZC71 alloy matrix and 12 vol% silicon carbide (SiC) particles were studied using linear polarization resistance, poten…
Abstract Extensive hydrothermal alteration is observed around volcanogenic massive sulfide deposits. These deposits are related to Late Cretaceous volcanism in various parts of the Eastern Pontide province. Mineral assemblages resulting from alteration consist of mostly clay minerals and silica polymorphs, some sulfat…
The syntheses and structures of the two mixedvalence crystalline molybdenum blue compounds Na26[Mo142O432(H2O)58H14] · ca. 300 H2O (1) (containing the maximal number of well defined defects which influence the overall structure and the reactivity of the anionic cluster) and Na16[(MoO3)176(H2O)63(CH3OH)17H16] · ca. 600…
Abstract The results of an experimental study on the effect of processing variables and filler concentration on the electrical resistivity of conductive composites based on nylon 6 filled with carbon black are reported. A typical percolation behavior in the effect of electroconductive filler content on the resistivity…
Thermogravimetry, derivative thermogravimetry (TG, DTG), differential scanning calorimetry (DSC) and X ray diffraction powder patterns have been used to study trimethoprim, sulfamethoxazole, ampicillim, tetracycline hydrochloride and rifampim. The results revealed the extent of their thermal stability and also allowed…
The interaction of R 2 AlH with cyclic siloxanes leads to rupture of the silicon−oxygen framework and yields aluminum polysiloxides. The room-temperature reaction of R 2 AlH with (Me 2 SiO) 3 yields the asymmetrical siloxide compounds R 2 Al(μ-OSiMe 2 H)(μ-OSiMe 2 OSiMe 2 H)AlR 2, R = t Bu ( 1 ), i Bu ( 2 ). In contra…
Biomimetic control over the hierarchical structure of inorganic materialsusing ordered organic surfaces can give rise to elongation and uniaxial alignment, shown here for mesostructured silica particles (see Figure). The alignment direction was normal to the axis of the polymer chains of the Langmuir–Blodgett film, wh…
Abstract The Scherrer equation links the measured width of an X-ray diffraction peak (Scherrer width, SW) to the number of stacked cells ( N ) in the direction normal to the diffracting planes. The formula is only valid for one d -value occurring in the coherently diffracting domain. This equation can be modified for…
The study of twisting crystalline orientation in banded polymer spherulites has recently been revitalized by availability of optically active macromolecules that crystallize exclusively in isochiral (uncompensated) helical conformations. In such cases, handedness of twisting appears to be rigidly controlled by chirali…
The photodegradation of the azobenzene chromophore DR1 {4-[N-ethyl-N-(2-hydroxyethyl)amino]-4(?)-nitroazobenzene]} incorporated as a side chain or as a guest in a poly(methyl) methacrylate host has been evaluated as a function of wavelength, temperature, and the atmospheric environment. The effects of these variables…
The structure of dense grafted polyelectrolyte layers has been studied with a combination of neutron reflectivity and infrared spectroscopy techniques. The polyelectrolyte brushes were made of poly(styrene sulfonate) neutralized by different counterions. Small counterions are distributed throughout the brush in order…
Symmetric collision between two identical plates has yielded successful theoretical models for the jetting process. Consequently, assessment of impact jetting at planetary scales has been largely based on the theories developed for such specific types of collisions. Little experimental work has been done, however, to…
Polymerization-induced phase separation to form polymer-dispersed liquid crystals (PDLCs) is a complex process involving simultaneous curing and phase separation to form nematic microdomains. Real-time FTIR spectroscopy has been used to simultaneously observe and quantify the curing process using a model system a fast…
To understand the interactions and functional role of each of the three mitochondrial NAD(+)-dependent isocitrate dehydrogenase (IDH) subunits (alpha, beta, and gamma), we have characterized human cDNAs encoding two beta isoforms (beta(1) and beta(2)) and the gamma subunit. Analysis of deduced amino acid sequences rev…
A influência da aplicação de resíduos vegetais na dinâmica de íons em solos ácidos é pouco conhecida. Neste estudo, a mobilidade de íons em amostra do horizonte Bw de um Latossolo Vermelho-Escuro álico lixiviado com soluções puras de ácidos cítrico e succínico e extratos aquosos de resíduos de nabo forrageiro (Raphanu…
Phase-ordering dynamics in nematic liquid crystals has been the subject of much active investigation in recent years in theory, experiments, and simulations. With a rapid quench from the isotropic to nematic phase, a large number of topological defects are formed and dominate the subsequent equilibration process. Here…