Materials Literature
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Systematic ab initio calculations of lattice constants, elastic constants and magnetic moments of Fe, Co and Ni in bcc, fcc and hcp structures have been carried out, in part to understand the phase stability and magnetic properties of artificial Fe, Co and Ni structures. The calculations are based on the local spin-de…
An avalanche of physical and physicochemical phenomena, often self-sustained, leads to the end of life of an insulating material. The collapse of the insulating role of a material is mostly due to the electrical field stress. The path leading from the catastrophic situation, the breakdown, back to its origin is follow…
Metal sulfide cores self-encapsulated in shells of the same material are formed via the in-situ source–template interface reaction route described by these authors. In this method, reaction occurs at the static organic/aqueous interface to produce peanut-shaped nanostructures of either CdS or ZnS (see Figure). A mecha…
In Escherichia coli, gene products of the glp regulon mediate utilization of glycerol and sn-glycerol 3-phosphate. The glpFKX operon encodes glycerol diffusion facilitator, glycerol kinase, and as shown here, a fructose 1,6-bisphosphatase that is distinct from the previously described fbp-encoded enzyme. The purified…
A novel 1-D chain of Cu(II) with alternate single end-on and single end-to-end azido bridge having a very high Cu−N3(1,1)−Cu bond angle (129.98°) has been synthesized and characterized, which shows an intrachain antiferromagnetic interaction (J = −11.5 cm-1 for end-on bridge and −2.7 cm-1 for end-to-end bridge).
High-temperature susceptibility measurements have indicated that the spin states of Mn and Co are different in the two different phases of the ferromagnetic oxide ${\mathrm{LaMn}}_{0.5}{\mathrm{Co}}_{0.5}{\mathrm{O}}_{3}.$ Mn and Co ions are present in their trivalent state as high-spin ${\mathrm{Mn}}^{3+}$ and low-sp…
Synchrotron x-ray-diffraction experiments have been carried out in a perovskite-type vanadium oxide ${\mathrm{YVO}}_{3}$ to elucidate orbital ordering of the system. The change from C- to G-type orbital ordering at the lower magnetic transition temperature was strongly suggested. The long-range orbital ordering appear…
Silicon nitride undergoes hydrolysis and dissolution when subjected to an aqueous environment. Molecular dynamics simulations suggest that hydrolysis proceeds through nucleophilic attack of water with the formation of an intermediate molecular complex involving a pentacoordinated silicon. We found that the dissolution…
ABSTRACT: Physicochemical characteristics (molecular weight, nitrogen, ash, degree of deacetylation, bulk density, viscosity, and residual amino acids) of 6 commercial chitosans differed with products. Significant correlations were observed between molecular weight and viscosity and between nitrogen and degree of deac…
This review examines the use of self-assembly in the fabrication of ceramic mesostructures, emphasizing the use of amphiphilic surfactants and block copolymers. The association between this area of research and biomimetics is discussed, linking developments in synthetic self-assembly with biomineralization. The fabric…
Experimental studies of dynamic magnetic properties of a highly homogeneous sample of ${\mathrm{La}}_{0.95}{\mathrm{Sr}}_{0.05}{\mathrm{CoO}}_{3}$ perovskite evidence the existence of a low-temperature spin-glass phase. A dynamic scaling analysis of ac susceptibility data according to conventional critical slowing dow…
A comparison of 25 Mg magic angle spinning (MAS) NMR spectra of crystalline and glassy diopside (CaMgSi 2 O 6 ) reveals that the chemical shift in the disordered phase corresponds to that of the mineral, suggesting that sixfold coordination is essentially retained upon vitrification. Likewise, a crystalline leucite an…
The thermomechanical behavior of a high‐alumina refractory that contains 10 wt% of synthetic spinel has been studied. Results have been correlated with the microstructural and mineralogical evolutions using X‐ray diffraction and scanning electron microscopy, as function of the firing temperature. Dry, castable, raw‐ma…
A novel device for capillary-free mounting of protein crystals is described. A controlled stream of air allows an accurate adjustment of the humidity at the crystal. The crystal is held on the tip of a micropipette. With a video system (CCD camera), the two-dimensional shadow projections of crystals can be recorded fo…
Direct photochromism is observed for the mesostructured host–photochromic guest system reported here. Block-copolymer/silica mesostructures were used as hosts for two photochromic dyes, a spirooxazine and a spiropyran. It is shown that the dyes are incorporated predominantly within the hydrophobic occlusions of the me…
The bursting strength of cotton plain knitted fabrics is predicted before manufacturing using intelligent techniques of neural network and neuro-fuzzy approaches in this re search. Among many parameters that affect fabric bursting strength, fabric weight, yarn breaking strength, and yarn breaking elongation are input…
A fundamental understanding of precipitation reactions is based on information about the structural evolution of the system on all length scales and starting at the beginning of the reaction. We introduce X-ray microscopy as an additional analytical tool in order to achieve this understanding. X-ray microscopy combine…
Quantum-chemical calculations at the B3LYP level have been carried out to elucidate the reaction mechanism of the epoxidation of ethylene with the molybdenum diperoxo complex MoO(O 2 ) 2 OPH 3 . All relevant transition states and intermediates which belong to the reaction pathways suggested by Mimoun and by Sharpless…
The photophysical properties of the lowest excited singlet states, S 1 (π,π*), of two porphyrin diacids have been investigated. The diacids are H 4 TPP 2+ and H 4 OEP 2+, the diprotonated forms of free base tetraphenylporphyrin (H 2 TPP) and octaethylporphyrin (H 2 OEP), respectively. Both diacids exhibit perturbed st…
In contrast to dendrimers, hyperbranched polymers show no distinguishable interior and periphery. Hyperbranched polyglycerol, however, possesses two types of OH functionalities (arising from linear and terminal glycerol units), which can be chemically differentiated. To generate a core−shell-type architecture in hyper…