Materials Literature
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The application of single step or multiple anodic potential steps to highly concentrated solutions of N -vinyl-2-pyrrolidone leads to the formation of poly( N -vinyl-2-pyrrolidone) (or PVP) films on platinum electrodes. These films are insoluble in a good solvent of the commercial polymer. Multiple potential steps yie…
A convenient new synthetic route to metallo-1,2-enedithiolates was applied to the synthesis of (dppe)M{S 2 C 2 (heterocycle)(H)}; dppe = 1,2-bis(diphenyldiphosphino)ethane, M = Ni, Pd, and Pt, and heterocycle = 2-quinoxaline, 2-, 3-, and 4-pyridine, and 2-pyrazine. These complexes were prepared from the corresponding…
The structure of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) has been reinvestigated by a combination of electron diffraction, high-resolution imaging, simulations of electron diffraction patterns and images, and packing energy calculations. A new model is proposed that is capable of explaining the large second harmon…
Orientational order and mobility of nematogens adsorbed in nanoporous glass are investigated by 1H and 13C NMR and broadband dielectric spectroscopy. For the mesogen 5CB, we detect local nematic order in cavities of 2. 5, 5. 0 and 7. 5 nm diameter. Quantitative measurements of the order parameter are reported. The nem…
The compound Na(5)Sn(13) forms in the sodium-tin system in high yield following prolonged reaction of a quenched mixture at 280 degrees C in a Ta container. The compound exhibits a complex three-dimensional structure (29 independent atoms) built mainly of 4-bonded tin atoms in interbonded pentagons (orthorhombic, spac…
Approaches are described for the analysis of XPS signals from samples comprising thin conformal coatings on substrates with non-ideal surface topography. In particular, attention is focused on arbitrarily shaped rough or curved substrates. Relations are derived for the relative x-ray photoelectron intensities emitted…
Abstract New “unsymmetrical” (mixed ligand) metal dithiolate complexes, expected as components of molecular conductors, have been obtained by a ligand-exchange reaction in refluxing acetone, followed by isolation with a preparative HPLC (ODP; acetonitrile-H2O). Their electrochemical data suggest that the acceptor (don…
Matrix isolation IR spectroscopy and high-level ab initio calculations were applied to investigate the structure and vibrational spectra of quinone−pyrimidine heterodimers formed in low-temperature Ar matrices. A specially developed experimental technique was used to separate bands of quinone−pyrimidine dimer from ban…
The effect of anisotropy in thermal vibrations on dynamical electron diffraction by a crystal is investigated. Expressions are first derived for both the elastic and thermal diffuse scattering (TDS) absorptive atomic scattering amplitudes for the general case of anisotropic thermal vibrations. These expressions are th…
We report here the discovery of a new bcc 1/1 crystal approximant (W-phase) to the stable icosahedral quasicrystal (i-phase) discovered recently in Ti-Zr-Ni alloys. As-cast Ti-Zr-Ni ingots, which originally contain only the C14 Laves and the hcp solid-solution phases, transform almost completely to the i-phase after a…
A novel laminar oxide composite was developed. This oxide laminate, which was fabricated by hot pressing, consisted of three types of layers, which were stacked in a repeating sequence of YPO4, yttria‐stabilized ZrO 2 , 30 vol% yttria‐stabilized ZrO 2 ‐70 vol% Al 2 O 3 , and yttria‐stabilized ZrO 2 . The behavior of t…
Solid solutions in the Gd 2 (Ti1‐yMoy)2O7 pyrochlore system, with y = 0.1, 0.3, 0.5, and 0.7, have been investigated as potential candidates for the anode material of solid‐oxide fuel cells. The electrical conductivity, stability range, and optimal synthesis conditions of the pyrochlore phase have been explored by ele…
We present an experimental technique for the inflation of freely suspended films of thermotropic smectic liquid crystals to macroscopic bubbles. These bubbles have many properties in common with well known lyotropic soap bubbles, but on the other hand represent a completely different class of material with different p…
The grain-size dependence of nanoscale ordered regions in Pb(Mg 1/3 Nb 2/3 )O 3 (PMN) has been studied using lattice images obtained by transmission electron microscopy. It was found that the size of nanoscale ordered regions, which is strongly related to dielectric properties, depends on the grain size. The nanoscale…
We present results on the spatial distribution of sodium cations in sodium tellurite glasses as a function of sodium oxide content, obtained using a spin-echo NMR experiment. Glasses were studied with sodium oxide content ranging from 10 to 30 mol %. From the decay rate of the spin echo we infer the proximity of sodiu…
Spectroscopic techniques are used to investigate energy transfer and radiation-induced reactions on the surfaces of particulate silicas. Upon subjection to high energy radiation, hydrogen atoms are produced with significant yields in all silica samples pretreated at 150 °C, for an example, G (H) = 4.2 in silica gel Da…
The present necessity to use heat-resistant materials in electronics justified the scientific interest in different heterocyclic polymers. This paper is especially concerned with the preparation of novel heat-resistant materials having benzimidazole moieties in the main chain. The poly(ether benzimidazole)s were prepa…
UDP-galactose 4-epimerase plays a critical role in sugar metabolism by catalyzing the interconversion of UDP-galactose and UDP-glucose. Originally, it was assumed that the enzyme contained a "traditional" catalytic base that served to abstract a proton from the 4'-hydroxyl group of the UDP-glucose or UDP-galactose sub…
We have studied stable structures of hydrogenated Si clusters grown from silane gas in an ion trap developed for cluster growth. The grown clusters were extracted from the ion trap through two different pathways and were analyzed by mass spectrometers. The Si6Hx+ cations were stably grown, among them clusters with x=1…
Oligomerization of a mixture of monomeric iron(III) 2-hydroxy-5,10,15,20-tetraphenylporphyrin, (2-OH-TPP)Fe(III)Cl, manganese(III) 2-hydroxy-5,10,15,20-tetraphenylporphyrin, (2-OH-TPP)Mn(III)Cl, and gallium(III) 2-hydroxy-5,10,15,20-tetraphenylporphyrin, (2-OH-TPP)Ga(III)Cl, complexes affords the series of heterometal…