Materials Literature
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Theoretical studies of the vibrational excitations of charged solitons in polyacetylene are reported. Two strongly infrared active modes, derived from bulk optical phonons, are associated with these defects and we suggest the presence of a third, as yet unobserved, infrared-active mode in the acoustic phonon regime.
The in situ temperature coefficient of resistance of palladium films in the thickness range 25-370 AA is reported. The Fuchs theoretical curve agrees with experimental alpha versus t curve for a specularity parameter p=0.88. The thickness dependence of the temperature coefficient of resistance gives the bulk mean free…
The effects of oxidation on the electrical conduction of low- and high-density polyethylene (LD-PE and HD-PE) have been studied. It has been found that oxidation enhances the carrier mobility in LD-PE, but lowers that in HD-PE. A qualitative explanation of these opposing effects is given, based on the assumption that…
The behaviour of systems which exhibit both commensurate and incommensurate phases is studied for a discrete lattice model. Close to the lock-in transition the incommensurate phase is shown to be well described by a soliton theory in which the solitons may be pinned to the lattice. This pinning effect leads to a 'devi…
The Raman spectra of the layer-type magnetic materials of formula (CH 2 ) n (NH 3 ) 2 CuCl 4 , n=2, 3 and 5, have been measured at various temperatures above and below their respective magnetic ordering temperatures and in a magnetic field up to 10 kOe. For all three crystals, the Raman spectra excited at energies ran…
For pt.I see ibid., vol.13, p.4671 (1980). The theory of boundary scattering of phonons in crystals of small size that also display substantial point-defect scattering is summarised. It is then applied to the analysis of the previously presented experimental results on Ge 30 Si 70 at 300K and 600K and on Ge 70 Si 30 a…
The thermal conductivity of polycrystalline Ge 30 Si 70 has been determined at and above room temperature for samples having a wide range of porosity and mean grain diameter. It has been established that the thermal conductivity at 300K is completely dominated by the lattice contribution and that its value varies line…
Radiological surveys at some former uranium ore processing facilities have indicated the presence of significant quantities of 219 and its daughters. Due to the extremely short half-life of actinon, it has traditionally been assumed that its activity is negligible in comparison with 222Rn. This paper discusses the pro…
Ralf Conrad, Wolfgang Seiler; Photooxidative production and microbial consumption of carbon monoxide in seawater, FEMS Microbiology Letters, Volume 9, Issue 1,
Abstract The electronic spin–spin relaxation is induced by a dipolar magnetic coupling between the spin states of a pair of paramagnetic ions, whereas the interaction between spin states and lattice vibrations is responsible for the spin–lattice relaxation. Two‐phonon Raman and Orbach spin–lattice relaxation processes…
In aged titanium tritide Ti 3 Hex thin films the 3He local critical concentration is slightly technology dependent and appears not to depend on the initial overall tritium concentration for x values lower than 1.5, which in fact results from a two-phase system: Ti and Ti 3H1.5. As it is not possible to increase signif…
The amount of glucose that can be synthesized from a protein depends on its amino acid (AA) composition. This value is about 60 g from 100 g of liver or muscle protein and is based on a knowledge of the total AA content and the proportion of each AA that can be converted to pyruvate. The maximum quantity of glucose in…
Derivative lattices are related to one another by transformation matrices having rational elements. A simple algorithm for finding these matrices consists in testing if the scalar products of the vectors defining two arbitrary primitive cells of two lattices can be exactly or approximately related by equations with ra…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFlavonoid Glycosides in Ammannia coccinea (Lythraceae)Shirley A. Graham, Barbara N. Timmermann, and Tom J. MabryCite this: J. Nat. Prod. 1980, 43, 5, 644–645Publication Date (Print):September 1, 1980Publication History Published online1 July 2004Published inissue 1 September…
Graft copolymerization of vinyl acetate (VAc) onto cellulose has been studied in an aqueous medium in the presence of Fe(acac)3, Al(acac)3, and Zn(acac)2 as initiators. Percentage of grafting has been determined as a function of concentration of initiators and monomer, reaction time, and temperature. The reactivities…
Abstract Aufgrund einer Analyse der Eigenschaften der heute bevorzugten Verstärkungsfasern aus Glas und Kohlenstoff wird gezeigt, daß es anorganische Materialien gibt, die die Vorteile der obigen Fasern unter Vermeidung deren Nachteile vereinigen. Als repräsentative Beispiele werden die Borfaser, die Siliziumkarbidfas…
Abstract Main results of research on poly (vinyl chloride) (PVC) stabilization are discussed. Stabilization is viewed from the standpoint of the modern notions of the reasons for PVC low thermal stability, the complicated nature of its dehydrochlorination, and the kinetics of its degradation. The internal unsaturated…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMetal-metal stretching frequencies in metal-cluster complexes. Approximate force constant calculations for some small metal clustersIan A. OxtonCite this: Inorg. Chem. 1980, 19, 9, 2825–2829Publication Date (Print):September 1, 1980Publication History Published online1 May 2…
Abstract In previous papers of this series it was shown that it is possible to determine both the amount of methanol adsorbed in the interlamellar space of charge-deficient Ca-montmorillonite or of homoionic clays and the amount of methanol occluded in a system of micropores between clay particles. This paper deals wi…
The corrosion behavior of alloy 5052 and 99.99% aluminum in 3% NaCl is compared with that in natural and synthetic sea waters at pH 7.2 and 8.2. The differences in behavior observed with variations in pH, electrolyte, or temperature are reconciled in terms of the sea water carbonic acid system. It is suggested that a…