Materials Literature
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The structure of weakly charged temperature sensitive gels has been investigated in deformed state by means of small-angle neutron scattering (SANS). At low temperatures where the gel is in a good solvent, the scattered intensity pattern was isotropic even for deformed gels. When the temperature was raised to 42 °C, t…
Blends of polycarbonate/acrylonitrile–butadiene–styrene terpolymer (PC/ABS) and polycarbonate/maleic anhydride grafted ABS (PC/MABS) were prepared over the whole range of compositions using a single-screw extruder. Tensile, flexural, notched Izod impact properties, and the heat deflection temperature of these blends w…
Fractoluminescence and charge emission upon three-point-bending fracture of synthetic and natural quartz crystals have been studied. Broad luminescence bands centered at about 2.0, 2.9, and 5.0 eV have been observed in both cases. Time-resolved luminescence measurement could be performed on the 2.0 and 2.9 eV bands. T…
Wodginite (ideally MnSnTa 2 O 8 ), and the rarer species, ferrowodginite (ideally Fe (super 2+) SnTa 2 O 8 ) and titanowodginite (ideally MnTiTa 2 O 8 ), have been discovered in rare-element granitic pegmatites of the complex type, petalite subtype, which occur in the Separation Rapids pegmatite field, northwestern On…
It was found that the activity of Pt catalyst films interfaced with disks can be reversibly modified upon application of constant currents or potentials through the cell Negative current (or potential) application causes up to threefold enhancement in the rate of ethylene oxidation at temperatures 450–510°C. The rate…
A complete analysis of the line shape of the excitonic absorption and photoluminescence lines of the yellow series of Cu2O is given. A detailed fit to the absorption lines up to the n = 5 exciton according to Toyozawa's theory gives precise values for the excitonic resonance energies, allowing to calculate the exciton…
Three series of methacrylate homopolymers with oligo(hexafluoropropene oxide), (HFPO) n, side groups and copolymers based on methyl methacrylate were prepared by free radical polymerization. Each series consisted of a polymethacrylate backbone with substituted HFPO side chains of different length ranging from the corr…
Decagonal quasicrystals in Zn-Mg-RE systems (RE = rare earth) have been studied for their composition and stability. The decagonal phase was shown to have the composition Zn Mg Dy in the Zn-Mg-Dy system. This phase 58 40 2 became a major phase after annealing and thus is apparently thermodynamically stable. Further, t…
Despite many years of intensive study, the natures of turnover-limiting and enantio-determining steps in catalytic asymmetric hydrogenation of prochiral enamides are poorly understood. An intriguing set of studies involving isotopic labeling distributions in catalytic enamide hydrogenation reactions were reported by B…
We are developing a novel three-dimensional (3D) microanalysis method by means of successive cross-sectional Auger mapping. In this method, a 3D elemental map will be obtained by repetition of the cross-sectioning of a sample using a gallium focused ion beam (Ga FIB) and Auger mapping of the cross section using an ele…
The importance of drying nanostructured semiconductors, such as porous silicon, in a controlled manner is explained. The mechanical instabilities that can arise during drying—resulting in cracking (see Figure) or peeling of the film—are discussed, as are methods that reduce or completely suppress these drying stresses…
The arterial wall injury associated with arterial graft implantation causes smooth muscle cells (SMCs) in the media to migrate and proliferate in the intima at the graft-artery junction resulting in anastomotic intimal hyperplasia (AIH). An important step in developing a small-diameter prosthesis may be to stimulate e…
We studied the dependence of thermodynamic variables in a sonoluminescing (SL) bubble on various physical factors, which include viscosity, thermal conductivity, surface tension, the equation of state of the gas inside the bubble, as well as the compressibility of the surrounding liquid. The numerical solutions show t…
Sintering of 0.5‐wt%‐MnO 2 ‐added Pb(Zr 0.53 Ti 0.47 )O 3 ceramics progresses at 935°C for 50 min by the addition of complex oxides of perovskite‐type crystal structure, BiFeO 3 and Ba(Cu 0.5 W 0.5 )O 3 . In order to elucidate the low‐temperature sintering mechanism of Pb(Zr,Ti)O 3 ceramics, the shrinkage and the evol…
Gradient polymers are two component polymeric systems in which the concentration of one component varies in a continuous way from one side to the other in systems with plane-parallel geometry. Such systems can be obtained from an amorphous polymeric matrix by diffusing into another monomer creating a gradient of conce…
Three series of ferroelectric liquid crystals have been synthesized, having three ester groups in the mesogenic core and one ester group in the chiral chain. The ester groups introduced into the core decrease the temperature of crystallization, which results in a broad temperature range ferroelectric smectic C phase i…
Structurally different carbon materials with an in- creasing sp 2 /sp 3 ratio were synthesized by pyrolizing cellulose materials at 400, 600, 800 and 1000 o C. The hybridization ra- tiosandtheinternalstructuresinthesesamplesweredetermined by using High Resolution Transmission Electron Microscopy, Electron Energy Loss…
We prepared luminescent silicon by incorporating H2O2 in the anodizing process. Under UV excitation, our samples appear reddish, orangish, yellowish to greenish as the electrolyte-air interface at the meniscus is approached. Under high current anodization, the emission becomes broad but unstable. The time characterist…
‘Scaled particle theory’ is applied to a two-dimensional fluid of hard ellipses. The model predicts a transition from the isotropic alignment of the ellipses to the two-dimensional nematic configuration in accordance with Monte Carlo simulations. By modifying the molecular shape it is possible to consider an ensemble…
Monte Carlo simulations are reported for the isotropic to nematic phase transition in semiflexible polymer melts. The molecules are modelled as tangent hard sphere chains with a bending energy that can be used to tune the stiffness of the chains. In the rod limit an isotropic to nematic transition occurs at high press…