Materials Literature
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Alternating current impedance spectroscopy and electron microscopy were used to investigate the effect of grain boundaries in LSGM‐based materials. The impurity LaSrGa 3 O 7 existing in the samples La 0.8 Sr 0.2 Ga 1‐ y Mg y ‐O 3–0.5(0.2+ y ) ( y = 0.05–0.10) gives a contribution to a perfect or depressed grain‐bounda…
PURPOSE: To evaluate the clinical utility and morphologic accuracy of gadolinium-enhanced excretory magnetic resonance (MR) urography after low-dose diuretic injection and to correlate the results with those of conventional urography. MATERIALS AND METHODS: In 71 patients with urologic symptoms, excretory MR urography…
Pure silica MCM-48 and MCM-41 materials were prepared using GEMINI surfactants, with the general formula [C n H 2 n +1 N + (CH 3 ) 2 −(CH 2 ) s −N + (CH 3 ) 2 C m H 2 m +1 ].2Br -, abbreviated as GEM n - s - m . The alkyl chain length ( n, m ) determines the pore size, whereas the length of the spacer ( s ) influences…
The three-dimensional structure of betaine aldehyde dehydrogenase, the most abundant aldehyde dehydrogenase (ALDH) of cod liver, has been determined at 2.1 A resolution by the X-ray crystallographic method of molecular replacement. This enzyme represents a novel structure of the highly multiple ALDH, with at least 12…
Mesoporous photocatalytic titanium dioxide films with periodic structures were prepared by molding from two-dimensionally ordered arrays of monodisperse SiO 2 particles. The morphology of the porous structures in these films was dependent upon the annealing temperature. The photocatalytic activity of the films was con…
New silicone derivatives that generate no toxic gas during combustion have been developed for use as flame retardants in the aromatic thermoplastics (polycarbonate and its derivatives, acrylonitrile–butadiene–styrene, polystyrene) used in many electronic devices. A special silicone with a branched chain structure, a p…
It has been controversial for many years whether in the cellulose of higher plants, the microfibrils are aggregates of 'elementary fibrils', which have been suggested to be about 3.5 nm in diameter. Solid-state NMR spectroscopy was used to examine two celluloses whose fibril diameters had been established by electron…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTPoly(p-phenylene-borane)s. Novel Organoboron π-Conjugated Polymers via Grignard ReagentNoriyoshi Matsumi, Kensuke Naka, and Yoshiki ChujoView Author Information Department of Polymer Chemistry Graduate School of Engineering Kyoto University Yoshida, Sakyo-ku, Kyoto 606…
Cubic silsesquioxanes, [RSiO 1.5 ] x , potentially offer access to organic/inorganic hybrids wherein the exact shape, size and mechanical properties of the inorganic component are perfectly defined. Furthermore, by tailoring the organic functionality bound to silicon, the inorganic/organic interface can also be perfec…
Fluoropolymers have many properties that are desirable in coatings. However, because of their poor solubility, formulating coatings containing fluoropolymers can be very difficult. Fluorine-based polymers that have been modified to increase their solubility have been used in a number of resin systems to bring the prop…
The electrical properties of tin oxide varistors doped with CoO, Nb2O5, and Cr2O3, were investigated using the impedance spectroscopy technique with the temperature ranging from 25 to 400 °C. The impedance data, represented by means of Nyquist diagrams, show two time constants with different activation energies, one a…
The effect of variations in temperature and oxygen partial pressure on the methane oxidation activity of α-alumina supported Pd catalysts was studied experimentally. It was found that after pretreatment at temperatures above 800°C, conditions where the metallic state of the catalyst is stable, “negative activation” oc…
The biosynthesis of structural materials in the form of fibers and biocomposites is unsurpassed—complex multicomponent composite structures can be made through seamless integration of polymer synthesis, mineralization, and self-assembly. The results of multidisciplinary research to understand structure/property relati…
For the past three decades, the electrocrystallization technique has been used extensively to assemble a large variety of molecular ions into long range ordered single crystals of high purity. This effort is reviewed in the present paper from the initial vigorous impetus triggered by the development of organic (molecu…
Ordering of Mn 3+ and Mn 4+ ions occurs in the rare earth manganates of the general composition Ln 1 - x A x MnO 3 (Ln = rare earth, A = Ca, Sr). Such charge-ordering is associated with antiferromagnetic and insulating properties. This phenomenon is to be contrasted with the ferromagnetic metallic behavior that occurs…
A close packed layer of Fe 3 O 4 and SiO 2 -coated Fe 3 O 4 nanoparticles can be assembled on silicon and glass substrates modified with polyelectrolytes following the principle of the layer-by-layer self-assembly ( Science 1997, 277, 1232). Microwave (MW) treatment of the poly(dimethyldiallylammonium chloride) layer…
The development of injectable nanoparticulate "stealth" carriers for protein delivery is a major challenge. We have shown the possibility of entrapping human serum albumin (HSA) in polyethylene glycol (PEG)-coated monodisperse biodegradable nanospheres with a mean diameter of about 200 nm, prepared from amphiphilic di…
New sensory materials based on polymer–transition metal hybrids are reported. It is demonstrated that by tuning the redox potential of the organic backbone—which is based on cobalt-containing N,N′-ethylenebis(salicylidenimide) (salen) complexes such as those shown in the Figure—high conductivity and high sensitivity t…
We report on a temperature dependence of the frequency of all the major peaks in the Raman spectra of carbon nanotubes, using different excitation laser powers at the sample. The frequency decreases with increasing temperature for all peaks, and the shifts in Raman frequencies are linear in the temperature of the samp…
Hybrid inorganic/organic materials show a remarkable range of materials behaviors. Here the author describes new chemistry for forming silicate networks with formic acid and in completely fluorinated solvents. The results of the surprising combination of grossly dissimilar materials such as fluoropolymers and polysili…