Materials Literature
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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…
The alteration of phase stability due to the continuous production of forced atomic displacements, as is the case under irradiation, is studied. A simple kinetic model of a binary alloy exhibiting phase separation is investigated, and two limiting cases are considered: nearest-neighbor ballistic exchanges and arbitrar…
We report the synthesis of octacationic macrocycles based on the porphyrazine (tetraazaporphyrin) core. The first stage is the synthesis of Mg(II) 2,3,7,8,12,13,17,18-octakis(4-pyridyl)porphyrazine, [Mgpz(pyr)(8)], and the parent [H(2)pz(pyr)(8)]. Both compounds are freely soluble in aqueous acid due to protonation of…
The synthesis of several new phthalonitriles 3, 9, 14, 25, 33, and 36, functionalised with carboxyl groups, including two examples of amino acid derivatives is described. All new phthalonitriles were converted into their corresponding phthalocyaninatozinc compounds. The phthalocyanines, 2,3,9,10,16,17,23,24-octa(1-car…
Earlier investigations by the authors showed that the tensile modulus of flax fibre mat polypropylene composites (NMT) could surpass the values of glass mat reinforced thermoplastic (GMT) on fibre weight basis. The tensile and flexural strength could reach values of up to 65% of the GMT strength values, however, very…
The local electrochemical and chemical characteristics of intrinsic breakdown sites on organically coated aerospace alloys were investigated. Local electrochemical impedance spectroscopy and mapping were used in conjunction with capillary electrophoresis, local pH, and local open‐circuit potential measurements to clas…
Pair particle nanostructures were prepared in porous anodic aluminum oxide films via a modified template synthesis procedure. By varying the interparticle distance of centrosymmetric gold spherical particles (radius ca. 32 nm), the linear UV/visible polarization spectra of the gold particle/porous alumina film composi…
The contamination performance of non-ceramic (NO insulators is better than porcelain insulators. The paper describes the pollution collection mechanism and concludes that silicone rubher insulators collect more pollution than porcelain insulators. Long term exposure of silicone rubber insulators produces a thin layer…
Abstract Simple shear plastic deformation behavior of polycarbonate (PC) plates due to the novel equal channel angular extrusion (ECAE) process is modeled using a commercial finite element methods (FEM) package. The true stress and true strain contour plots as well as the strain rate variation across the PC plate duri…
The increasingly widespread use of synchrotron-radiation sources and cryo-preparation of samples in macromolecular crystallography has led to a dramatic increase in the number of macromolecular structures determined at atomic or near-atomic resolution. This permits expansion of the structural model to include anisotro…