Materials Literature
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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…
ABSTRACT: This study measured the water vapor transmission rates (WVTR) and moisture sorption of chitosan films over a range of water vapor pressures at 25 °C. Films of a constant thickness were made using chitosan with 3 levels of deacetylation. Films were tested at test relative humidity (RH) difference between RH v…
For hard ellipsoids of revolution we calculate the phase diagram for the idealized glass transition. Our equations cover the glass physics in the full phase space, for all packing fractions and all aspect ratios X0. With increasing aspect ratio we find the idealized glass transition to become primarily driven by orien…
The lattice deformation of dense strained La0.7Sr0.3MnO3 (LSMO) films is shown to control the easy direction of the magnetization. Optimized pulsed laser deposited conditions allow the fabrication of dense LSMO thin films which present an exceptional flatness with a peak–valley roughness (Rp–v) of 1 Å, associated to e…
Eight glasses with molar Mg/2Al ≈ 1 in the system MgO-Al 2 O 3 -SiO 2 have been studied by magic angle spinning (MAS) NMR spectroscopy. Using triple quantum (3Q) NMR techniques we find evidence for significant concentrations of Al coordinated to five O atoms in all glasses, the proportion increasing with decreasing Mg…
Films of polystyrene (PS) and poly(methyl methacrylate) (PMMA) blend have been annealed at a temperature above their glass transition temperatures for up to 48 h. Surface chemical compositions of the cast and annealed films were measured by X-ray photoelectron spectroscopy (XPS) while surface topographical changes wer…
Oblate and prolate ellipsoidal inorganic colloids can be synthesized by combining colloidal chemistry and ion irradiation techniques, as reported here. It is found that dramatic anisotropic plastic deformation of monodisperse silica and zinc sulfide microspheres occurs under 4 MeV Xe ion irradiation (see Figure). Poss…
A single crystal of the title compound [MnII6(H2O)9[W(V)(CN)8]4 x 13H2O]n was synthesized in a hot aqueous solution containing octacyanotungstate, Na3[W(CN)8] x 3H2O, and Mn(ClO4)2 x 6H2O. The compound crystallized in the monoclinic system, space group P2(1)/c with cell constants a = 15.438(2) A, b = 14.691(2) A, c =…
The reaction of manganese(II) and pyridine derivatives such as 3-methylpyridine (3-Mepy) and 3,4-dimethylpyridine (3,4-Dmepy) led to the new one-dimensional systems trans-[Mn(3-Mepy)2(N3)2]n (1) and trans-[Mn(3,4-Dmepy)2(N3)2]n (2). Compound 1 crystallizes in the monoclinic system, space group P2(1)/n, a = 11.201(3) A…
We have investigated the structure and electronic properties of ferrimagnetic double perovskites, ${A}_{2}{\mathrm{FeReO}}_{6}$ $(A=\mathrm{C}\mathrm{a},\mathrm{ }\mathrm{S}\mathrm{r},\mathrm{ }\mathrm{Ba}).$ The $A=\mathrm{Ba}$ phase is cubic $(\mathrm{Fm}3m)$ and metallic, while the $A=\mathrm{Ca}$ phase is monoclin…