Materials Literature
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Nanosecond laser flash photolysis and pulse radiolysis have been used to characterise the excited states and radicals of meso-tetraphenylporphyrin tetrasulphonic acid as the tetrasodium salt (Na4TPPS) and of meso-tetra-N-methylpyridylporphyrin as the tetra-p-toluenesulphonate (TMPyrP). After 347 nm irradiation, aqueou…
At different times in the history of polymer science specific subjects have come to center stage; for intense investigation because they represent new and important intellectual challenges as well as technological opportunities. In past years the chief incentive for the scientific study of biodegradation of polymers w…
A model for the dynamic oxygen concentration in silicon melts during Czochralski growth is presented. The model is found to be in good agreement with experimental results and to account for first order effects on both the absolute oxygen concentration and its axial variations in grown crystals. Approaches aimed at ach…
The channelling of ions in crystals is described and its application to the study of a variety of lattice defects is outlined. Ions which are channelled along different crystallographic axes and planes interact with displaced atoms in distinctive ways, enabling the atomistic nature of lattice defects to be determined.…
Nickel-copper alloys are widely used as catalysts. The chemical and physical properties of Ni-Cu alloys and their catalytic properties have been described quite extensively in the literature. Copper appears to be practically inactive for the hydrogenation or other related reactions unless some promotor is present with…
The publication date of the first edition is not stated, but the new edition is apparently considerably revised and expanded. It was written to serve as a multi-purpose text at the senior or graduate level and as a reference for the practicing scientist or engineer. Readers should have a math backgr
When kaolinite is heated for differential thermal analysis (DTA) the second exothermic peak (∼1275°C) is due to growth of mullite crystals accelerated by formation of a liquid phase. The third exothermic peak (∼1460°C) is due to crystallization of cristobalite. Addition or presence of impurity oxides causes the second…
Aspirin crystals having different types of habits were prepared by recrystallization of commercial products from various solvents. The difference in crystal habits was investigated crystallographically and optically by the use of a polarizing microscope to measure habit parameters a, b, and c. The dissolution behavior…
Research into plugging and related processes, such as punching and blanking, is briefly reviewed and discussed with emphasis on understanding thephysical aspects of the process and its mechanical description. Based on progress in the study of thermoplastic shear instability, a mechanical model isproposed which concent…
Photochromic polymers containing p-phenylazoacrylanilide were synthesized and the photo-induced hydrophobicity change on the surface of the polymer film was studied by measuring water wettability. The wettability increased with UV irradiation and returned to the original value with visible light irradiation. This phot…
Abstract The usual method of studying thermal degradation mechanisms of polymers in vacuo is to use electron ionization pyrolysis mass spectrometry. This can lead to mass spectral fragmentation from the 70 eV electrons used. Low energy electrons (10–15 eV) produce a low abundance of positive ions. However, if a molecu…
A theoretical analysis of the order parameter and temperature dependence of the complete set of five independent viscosities of incompressible nematic liquid crystals is presented. It is an extension of a previous theory by the authors on the thermal dependence of the twist viscosity in nematics (Port. Phys. 9 (1975)…
Exposure of MgAl2O4 crystals to 137Cs γ rays produces a broad absorption complex centered near 3 eV and at the same time destroys absorption at 4.8 and 6.4 eV which is attributed to charge transfer transitions on octahedral Fe3+ impurity ions. Thermal and optical bleaching of the 3-eV absorption complex in crystals wi…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTApplicability of the Solomon-Bloembergen equation to the study of paramagnetic transition metal-water complexes. An ab initio SCF-MO studyLars Nordenskiold, Aatto Laaksonen, and Jozef KowalewskiCite this: J. Am. Chem. Soc. 1982, 104, 2, 379–382Publication Date (Print):Januar…
This book contains the papers and discussions from the symposium, "PARTICU LATE CARBON: Atmospheric Life Cycle," held at the General Motors Research Laboratories on October 13-14, 1980. This symposium
We have measured cross sections for the production of isotopes of Bk through No in bombardments of $^{248}\mathrm{Cm}$ with $^{16}\mathrm{O}$, $^{18}\mathrm{O}$, $^{20}\mathrm{Ne}$, and $^{22}\mathrm{Ne}$ ions at energies near the Coulomb barrier. In general, the peak of the mass-yield curve for each element is about…
A detailed study of the reductive dissolution of NiFe2O4 by V(pic)–3 is reported. The kinetics of the reaction follow a cubic rate law and exhibit a first-order dependence on [VII], indicating that the rate-determining step involves attack by V(pic)–3 on FeIII ions at the oxide surface. Dependences on [H+] and [free p…
The electrochemical oxidation of NiL2+ (where L = meso-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) in aqueous solutions in the presence of sulfate, phosphate, chloride, and phthalate yields NiIIILX2. The stability constants for the axial coordination of the anions X are estimated from the observed red…
The annealing out of quenched-in vacancies has been studied, by transmission electron microscopy, in an ordered B2 type Fe-42 at.% Al single crystal. Slices of 〈111〉 and 〈001〉 orientation were quenched from 1000deg;C and annealed at 400deg;C for various times. In situ annealing has also been performed in a high-voltag…
EPR and electrical conductivity measurements under controlled thermal cycles demonstrate that a phase transition is occurring at about 22 K in (TMTSF)2ClO4. Slow cooling (12 K/h) yields a stable ground state exhibiting Pauli paramagnetism above and superconductivity below 1.2 K. In contrast, fast cooling (30 K/min.) y…