Materials Literature
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Temperature-programmed reaction spectroscopy has been used to study the surface reaction between CO and O-atoms on Rh(100) and Rh(111) at a range of different adsorbate coverages. Comparison of the reaction on both surfaces in the low coverage regime, where the kinetics can be described by a straightforward Langmuir–H…
We compare the crystallization behavior of thin films of Ge2Sb2.3Te5 in various amorphous states, namely, as-deposited, melt-quenched, and primed. These films are embedded in a quadrilayer stack similar in structure to the commercially available phase-change optical disks. This study shows that the melt-quenched amorp…
Two-dimensional (2D) photonic crystals were fabricated using anodic porous alumina with a highly ordered air-hole array of triangular lattice with a high aspect ratio of over 200. The transmission properties of the obtained ordered air-hole array in the alumina matrix exhibited a stop band in the spectrum which corres…
The influence of three dicarboxylate anions, oxalate, (C 2 O 4 ) 2 -, glutarate, (H 6 C 5 O 4 ) 2 -, and pimelate, (H 10 C 7 O 4 ) 2 -, on the self-condensation process of the [Mo 2 S 2 O 2 ] 2+ dithiocation has been investigated. [Mo 8 S 8 O 8 (OH) 8 (C 2 O 4 )] 2 - ([Mo 8 -ox] 2 - ), [Mo 10 S 10 O 10 (OH) 10 (H 6 C…
Polyoxometalates of colloidal size have been immobilized in a silica-matrix via sol-gel synthesis. The resulting (porous) materials exhibit the unique properties of both the polyoxometalates (POMs) and of the host silica. The pocket molded into the silica by the POM-cluster acts as a special nano-dimensional “reaction…
Raman scattering, 119Sn Mössbauer spectroscopy and temperature-modulated differential scanning calorimetry experiments have been performed on (Ge0.99 Sn0.01)x Se1−x glasses in the 0.30 < x < 0.36 range. Both Raman and Mössbauer spectroscopies show that Ge‒Ge signatures first appear near x = 0.31(1), and their concentr…
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…