Materials Literature
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In orientationally biased grand canonical ensemble Monte Carlo (GCEMC) simulations we investigated the microscopic structure of liquid-crystalline films confined between two plane parallel solid surfaces (i.e., walls) consisting of Ns discrete, rigidly fixed atoms. These wall atoms are distributed across the plane of…
A technique for producing ceramic preforms with graded porosity via colloidal infiltration of molded polymer sponges has been developed. Polymer sponges have been compression molded into various shapes with continuous and/or stepwise gradients in porosity. Infiltration of the graded sponge with ceramic slurry, followe…
Carbon nanotubes have a whisker-like structure so an extremely high strength and lack of plasticity are generally predicted. In-situ observations made by transmission electron microscopy, however, prove that carbon nanotubes bend plastically at room temperature. The bending process at the atomic level is suggested by…
Mössbauer spectrometry of natural samples of tourmaline shows the presence of Fe 2+ and Fe 3+ either in the Y (9b) or the Z (18c) sites, with intervalent iron delocalized between these sites. To understand the distribution of iron in natural samples, tourmaline was synthesized at temperatures from 400 to 700 °C, unde…
Magnetization and resistivity of CrO2 powders and oriented CrO2 films on different TiO2 single-crystal substrates are reported, and the low-temperature specific heat is measured on powders. The M(T) data follow a Bloch T3/2 law, with no sign of a spin-wave gap. The residual resistivity depends strongly on film texture…
La 1−x Li x MnO 3 (x=0, 0.1, 0.2, and 0.3) were synthesized by using conventional solid state reaction and partial melting technique. The compounds were determined to be of rhombohedral structure by x-ray powder diffraction. For the x=0.2 and x=0.3 samples, room temperature neutron powder diffraction patterns were col…
The structures of fast-ion-conducting glasses $(\mathrm{N}\mathrm{a}{Z)}_{x}({\mathrm{Na}}_{2}{\mathrm{O}\ensuremath{-}2\mathrm{B}}_{2}{\mathrm{O}}_{3}{)}_{1\ensuremath{-}x}$ and $(\mathrm{Li}{Z)}_{x}({\mathrm{Li}}_{2}{\mathrm{O}\ensuremath{-}2\mathrm{B}}_{2}{\mathrm{O}}_{3}{)}_{1\ensuremath{-}x}$ $(Z=\mathrm{C}\mathr…
The environmental scanning electron microscope allows the examination of virtually any specimen in a gaseous environment without the need for coating or drying. Experimental evidence, however, suggests that significant electron beam damage occurs in hydrated specimens. It is thought that water molecules, ionized by th…
Abstract Temperature programmed reduction (TPR) experiments were carried out over Pd/ZnO with different Pd loadings. Combined results with an X-ray diffraction method and X-ray photoelectron spectroscopy showed that a Pd–Zn alloy with a structure of PdZn was selectively produced in the course of TPR of Pd/ZnO. It was…
The silk of lepidopteran insects has been studied extensively as proteins of two categories: the fibroins, which are produced in the posterior section of silk glands, and the sericins, which are secreted in the middle section. We now describe a third category that is named seroins to accentuate the fact that both the…
Modified electrodes, suitable for use in flow injection analysis, have been obtained by the electrostatic assembly of films constituted by two different porphyrins, namely, μ-meso(tetrapyridyl)porphyrinatecobalt(III)tetrakis[bis(bipyridine)(chloro)ruthenium(II)] and meso-tetra(4-sulphonatephenyl)porphyrinatezinc(II),…
New functionalised macromers containing perfluoropolyether (PFPE) structures and methacrylic end groups were synthesised and used as modifying additives for acrylic UV-curable systems. Their chemical structure is Rh-Rf-Rh, where and with p ≈ q. Notwithstanding their very low concentration, below 0.5 wt.-%, the fluorin…
Poly(1,4-dioxan-2-one-co-trimethylene carbonate), P(DON-co-TMC), copolymers with different compositions were synthesized by copolymerizations of 1,4-dioxan-2-one (DON) and trimethylene carbonate (TMC) at 120°C in the presence of Sn(Oct)2. Their structures and compositions were determined with FT-IR and 1H-NMR spectros…
Abstract Partial segregation of reagents occurs when reaction rates exceed mixing rates and frequently causes product distributions to be mixing‐dependent. A simultaneous temperature segregation, whereby the temperature in a reaction zone differs from that in its surroundings, has rarely been considered when mixing re…
Alpha-Tocopherol concentrations were determined in the CSF of patients with early untreated Parkinson's disease receiving 2,000 IU vitamin E orally per day. After treatment the concentrations increased significantly (p < 0.001) by 76+/-10 (SE)%. The net increases in CSF alpha-tocopherol concentrations after treatment…
Direct evidence of half-metallic density of states is observed by scanning tunneling spectroscopy of ferromagnetic La0.7Ca0.3MnO3 and La1−xSrxMnO3 (x=0.3, 0.33) epitaxial films which exhibit colossal magnetoresistance (CMR). At 77 K, well below the Curie temperatures, the normalized tunneling conductance (dI/dV)/〈I/V〉…
Cold neutron triple-axis measurements have been used to investigate the nature of the long-wavelength spin dynamics in strongly doped La1−xSrxMnO3 single crystals with x=0.2 and 0.3. Both systems behave like isotropic ferromagnets at low T, with a gapless (E0&lt;0.02 meV) quadratic dispersion relation E=E0+Dq2. Th…
An experimental and theoretical analysis of finite size effects in submicron barium titanate particles is presented. The dielectric data show that the dielectric constant (∊ = 734) of small particles (d = 20 nm) remains very similar to that of single crystals provided that the particles are grown from an amorphous pha…
Abstract cis,cis,cis-1,3,5,7-Tetrahydroxy-1,3,5,7-tetraisopropylcyclotetrasiloxane (1) was synthesized. The X-ray crystallography of 1 revealed that four molecules of 1 and four molecules of water compose a cluster in the lattice. Dehydration of 1 with N,N'-dicyclohexylcarbodiimide (DCC) gave octa(isopropylsilsesquiox…
A recombinant hydroxylated fragment of human type III collagen has been produced in Saccharomyces cerevisiae by coordinated coexpression of a collagen gene fragment together with both the alpha- and beta-subunit genes for prolyl-4-hydroxylase (EC 1.14.11.2). The collagen fragment consisted of 255 residues of the helic…