Materials Literature
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LaRC ™ -SI (NASA Langley Research Center-Soluble poly Imide) is a wholly aromatic, high-performance thermoplastic with a unique combination of physical, mechanical and adhesive properties. LaRC ™ -SI is synthesized from equimolar amounts of the dianhydrides 4, 4′-oxydiphthalic anhydride (ODPA) and 3, 3′, 4, 4′-bipheny…
The stability of the perovskite phase was studied as a function of sintering temperature. Dielectric, piezoelectric and pyroelectric properties of relaxor ferroelectric in the (1 – x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 solid solution series have been investigated. An important contribution to the dielectric, pyroelectric and pie…
A direct imaging system is introduced to study the oscillations of microbubbles acoustically levitated in water. The bubble is illuminated with a light emitting diode (LED) which is strobed at a frequency different from the driving sound field. This technique slows the moving image of the bubble, allowing one to obser…
The dislocation substructure and the glide activity in cyclically deformed nickel single crystals have been studied using the channelling contrast of backscattered electrons in a scanning electron microscope. Dislocation arrangements which arise in the saturation region after cyclic loading at room temperature and at…
The molecular dynamics of supercooled liquids confined to the mesopores of sol-gel glasses are interpreted in terms of the spatial competition between the average length scale of cooperativity assumed to increase with time and the geometrical confinement on scales between 2.5 and 7.5 nm. Opposed to relating the fast a…
Random packings containing 8192 hard spheres in three dimensions have been built with an efficient computer algorithm for various packing fractions up to $c=0.643$, a value close to the upper limit ${c}_{b}\ensuremath{\simeq}0.649$. Long-range correlations and local order have been investigated via the calculation of…
Abstract Novel perylene‐containing polymers have been synthesized. They exhibit good solubilities in organic solvents and have good film forming properties. A water‐soluble perylene‐containing polyimide was obtained via sulfonation of the corresponding polyimide. Solubilities and spectral characteristics of these poly…
The physicochemical properties of an amyloidogenic mutant human lysozyme (Ile56Thr) were examined in order to elucidate the mechanism of amyloid formation. The crystal structure of the mutant protein was the same as the wild-type structure, except that the hydroxyl group of the introduced Thr56 formed a hydrogen bond…
Raman scattering experiments on metallic ${\mathrm{La}}_{0.7}$${\mathrm{Sr}}_{0.3}$Mn${\mathrm{O}}_{3}$ have been carried out using different excitation wavelengths as a function of temperature from 15 K to 300 K. Our data suggest a Raman mode attributed to electronic excitations centered at 2100 ${\mathrm{cm}}^{\ensu…
In this article, for the necessity of measuring the damping of new materials, a detailed comparison was made between two important free vibration torsion pendulums, that is, the inverted torsion pendulum and the Collette pendulum. Special attention was paid to the strong effect of the torsionally weak suspension in bo…
NOX control employing several combustion modification techniques is studied in batch annealing furnaces and ammonia combustion ovens in steel plants. The fuels of the annealing furnace and ammonia oven are by-product fuel gases and ammonia vapor, respectively, which are generated in the same steelworks. Study of the e…
Hydrogen permeation through thin films of Fe I– Y O on iron and through chemically polished iron were investigated by the sensitive electrochemical technique. The oxide was formed on the exit side of the sample membrane. The hydrogen arriving at the iron/oxide interface is in an atomic or protonic state which renders…
It has been established that phosphate analogues can activate glycogen phosphorylase reconstituted with pyridoxal in place of the natural cofactor pyridoxal 5'-phosphate (Change YC. McCalmont T, Graves DJ. 1983. Biochemistry 22:4987-4993). Pyridoxal phosphorylase b has been studied by kinetic, ultracentrifugation, and…
Abstract In order to influence the habit of barite (BaSO 4 ) single crystals obtained by precipitation, the tailor‐made additives 2‐aminomethanol, 3‐aminoproponal, 5‐aminopentanol, 4‐aminobutane sulfonic acid, and several other growth inhibitors have been tested. The crystallization experiments have been carried out i…
Abstract— A comprehensive study is reported of the chemical‐beam epitaxy (CBE) and metalorganic molecular‐beam epitaxy (MOMBE) growth of undoped and Mn‐doped ZnS on (100) silicon and GaAs substrates for applications in advanced electroluminescent displays and optoelectronic device integration. Low‐temperature photolum…
North Vietnamese NR latexes were successfully epoxidized using peracetic acid at moderate temperature and pH range. The epoxide contents of pure epoxidized natural rubber (ENR) are from 5 to 70 mol%. The ENR products were characterized and determined by spectral and thermal analysis besides the chemical titration. Con…
There have been few experimental reports on cryogenic two-phase fluids and cavitation phenomena using the irradiation of pulsed high-power laser. This paper describes an investigation of the behavior of laser induced cavitation bubble in cryogenic liquid nitrogen. The bubble is produced by a pulsed ruby laser focused…
Abstract The new quaternary europium polysulfide KCuEu 2 S 6 was obtained using the reactive flux method at an intermediate temperature of 380°C by reacting K 2 S 3 with elemental Cu, EuS and an excess of sulfur. The Eu 3+ ions exhibit a bicapped trigonal prismatic coordination and the Cu + ions are in a tetrahedral e…
The chemical reactions that take place at surfaces as well as internally in nanoscale particles are of great scientific interest. Such reactions control the catalytic properties of small metal particles and thus are technologically very important. In order to allow enhancement of the performance of such catalytic syst…
Abstract. Point defects in solids can give rise to anelastic relaxation provided that the defects behave as elastic dipoles. Experiments with single crystals give information on the atomic configuration of the point defects. Measurements of the orientation dependence of the relaxation strength allow determination of t…