Materials Literature
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The effects of surface discharges on dielectric properties of filled and unfilled epoxy resins have been studied. By means of parallel-plate electrodes, sheet samples have been aged through direct and indirect exposure to electric discharges at 15 kV ac 50 Hz voltage in static dry air for time intervals up to 300 hour…
Abstract Graphite electrodes modified chemically with poly(l-valine) and poly(N-acryloyl-l-valine methyl ester) were prepared. They were remarkably more durable than the corresponding dip-coated electrodes when used repeatedly in the electrochemical asymmetric reduction of citraconic acid.
Abstract The in‐plane component of the dielectric constant of chiral smectic p‐decyloxybenzilidene‐p'‐amino‐2‐methylbutyl cinnamate is measured as a function of temperature and magnetic field applied parallel to the smectic layers. The transition from the modulated smectic C* to the uniform smectic C phase is accompan…
Abstract A glow discharge polymerization technique was applied in the preparation of germanium‐containing polymers. The colorless and transparent polymer films formed from tetramethylgermanium (TMG) were investigated by elemental analysis, infrared (IR) spectroscopy, and ESCA. The reaction of TMG was accompanied by th…
Oxygen potentials for U 0.85 Zr 0.15 O 2+x solid solutions with the fluorite structure (prepared at 1500°C) were measured at 1500°C by a thermogravimetric technique. The oxygen potentials were 12 to 20 kJ/mol lower than those of pure UO 2+x at a given oxygen‐to‐metal ratio; they cannot be represented as a function of…
A brief review on liquid crystals shows that one-and two-dimensional structures are found in nature. Liquid crystals bridge the gap between the rigid solid state and essential absence of structure in the gaseous state.
The photochemical decomposition of semiconducting electrodes and the effects of charge exchange to redox species in solution have been studied by means of the Mirage Effect. Spectroscopic use of this method permits the detection of surface films and diffusion coefficients of redox ions generated by charge exchange at…
The results of a series of skin grafting experiments performed on the hindlimb of the newt Triturus cristatus are described. In an attempt to limit the position of origin and the complexity of supernumerary limb outgrowths four experimental features were varied. These were 1) size of skin grafts; 2) their position of…
The commensurate-incommensurate phase transition in the classical one dimensional double sine· Gordon (Ds-G) system is studied analitically. The energy density of kink lattice and the ratio of the mean misfit parameter (q) to the original one (qo) are calculated in order to discuss the phase transition. It is shown th…
The anisotropy of orientational order in cholesteric liquid crystals is investigated within a mean-field model of the cholesteric phase. It is shown that this biaxiality emerges as a direct consequence of the helical structure of the phase and the chiral character of the intermolecular interactions. The dependence of…
This paper describes two biaxial experiments which investigated time and rate effects in the yield and deformation behavior of type 316 stainless steel at room temperature. The first experiment was aimed at determining the effect of probing rate on small-offset yield behavior. The primary aim of the second experiment…
Gainesite, hypothetical end-member Na2Zr2[Be(PO ic], a : 6.567(3), c : 17.1196)4, Z = 2, tetragonal, space grottp l41lamd, is a new species from the Nevel (Twin Tunnels) pegmatite, Newry, Oxford County, Maine. Crystals occur as up to I mm simple tetragonal bipyramids with p{l11} dominant. The color is delicate pale bl…
Abstract High cis ‐1,4 ‐polybutadiene has been used to prepare toughened polystyrene in an attempt to improve its low temperature impact properties. A range of physical and mechanical properties was obtained by keeping the amount of rubber and the polymerization conditions constant, and varying the rate of agitation i…
Structure studies on the segmented polyurethane-urea based on poly(tetramethylene glycol), 4,4'-diphenylmethane diisocyanate, and 4,4'-diaminodiphenylmethane have been made using wide- and small-angle x-ray diffraction. It was found that the hard segments have a well-defined crystal structure indexed by a monoclinic u…
Both neutron diffraction and Mössbauer investigation reveal that CsFeS 2 remains paramagnetic down to 70 K, at which a sudden first order magnetic and structural phase transition takes place. Antiferromagnetic coupling of spins both along the c -axis and along the diagonal direction in the a - b plane of the orthorhom…
Inspection of uncoated insulating samples in a scanning electron microscope (SEM) is possible by using low beam voltages in order to minimize charging effects. In this paper, the principal parameters affecting the target potential under bombardment by electrons are considered. The influence of primary beam energy and…
<mml:math><mml:mrow><mml:mo>(</mml:mo><mml:mn>111</mml:mn><mml:mo>)</mml:mo><mml:mo>[</mml:mo><mml:mn>1</mml:mn><mml:mover><mml:mn>1</mml:mn><mml:mi>¯</mml:mi></mml:mover><mml:mn>0</mml:mn><mml:mo>]</mml:mo></mml:mrow></mml:math> crystals of pure Cu–Al203 (particle size < 200 nm) have been strained between 5 and 204%…
Dynamic recrystallization (DRX) of Cu single crystals during tensile deformation in creep at elevated temperatures (0·6 ≤ T/T m ≤ 0·9) was investigated. At very high temperatures (T ≤ 0·8 T m), DRX occurred after steady state creep had been attained, while DRX commenced before deformation became stationary for lower d…
A procedure for Rietveld refinement from Debye–Scherrer X-ray diffraction patterns is described, in which the effects of instrumental aberrations on the peak shapes and positions are calculated and incorporated into the refinement model. These aberrations, neglected in previous Rietveld refinement programs, can produc…
Abstract The elastic field of a dislocation piercing the interface of an anisotropic bicrystal is obtained for the general case of a dislocation line refracted at the interface. The theory is based on the method of dislocation‐line force fans which reduce the three‐dimensional elastic field of the dislocation in the b…