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Abstract Two types of fluorosilicone polymers are described, the poly(fluoroalkyl)-siloxanes and the hybrid fluorocarbon silicones. The first type, represented by the structure (CF 3 CH 2 CH 2 SiMeO) n exhibits good solvent resistance, thermal and oxidative stability and is commercially available in the form or rubber…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPreparation of new complex metal hydrides. Potassium tetrahydrozincate and sodium tetrahydrozincateE. C. Ashby and R. G. BeachCite this: Inorg. Chem. 1971, 10, 11, 2486–2488Publication Date (Print):November 1, 1971Publication History Published online1 May 2002Published iniss…
The synthesis and nuclear‐magnetic‐resonance spectra of N ‐fluoroacetyl‐ d ‐glucosamine are described, together with 19 F chemical shifts for some monosaccharides substituted with fluorine at different positions. The sugar derivative N ‐fluoroacetyl‐ d ‐glucosamine is inhibitory towards lysozyme, 50% of full inhibitio…
Abstract The diffusion coefficient D and solubility coefficient k of small molecules [C 3 H 6 , C 4 H 10 , (CH 3 ) 4 C] are determined at very low solute concentrations in annealed linear polyethylene over a wide range of temperature above and below the melting point T m . For measurements above T m the specimen was l…
Abstract It is shown that NMR-linewidth measurements are useful to obtain information about the crosslink density and the average distance between the crosslinks in vulcanized rubber. Inhomogeneous structure of the rubber phase in carbon black-filled rubber is evidence and the thickness of the rubber layer on carbon b…
Abstract For some time, polyimides have enjoyed a significant degree of superiority over the other classes of thermo‐oxidatively stable polymers. This superiority is, however, offset by the tremendous difficulty associated with the processing of polyimides. In an effort to understand these difficulties and their cause…
Dielectric polarization, whose activation energy is nearly equal to that of the electrical conduction, has been found in many alkali-silicate glasses and is presumed to be due to the migration of alkali metal ions1,2or some special type of interfacial polarization.3However, the mechanism of polarization has not yet be…
The effects of a number of related diols, substituted diols and glycerol on the thermal stability of acid-soluble calf skin collagen were investigated. Thermal transition temperatures were determined by optical rotation measurement. Short-chain diols with terminal hydroxyl groups, i.e. ethylene glycol and propane-1,3-…
The purpose of this paper is to re port on the development of a system of treatment of wastewater designed to produce different quality effluents suit able for disposal into receiving bodies of water or for reuse. The system has three component parts that can be used either separately or sequentially. The wastewater i…
Two problems in the theory of nematic liquid crystals are formulated. One is concerned with the change of orientation due to magnetic field and the other with shear flow. The solutions of the governing differential equations explain the physical phenomena which have been observed experimentally, namely the alignment o…
When the α-UO3, La2O3 and NaCl structure types are idealized by a topological distortion involving only an extension or contraction of the hexagonal c axis (cubic [111]) it is clear that they are related to each other, and to the CaF2 type, by crystallographic shear. A number of lanthanide and actinide oxide structure…
Lactic dehydrogenase from pig heart isoenzyme (H 4 ) and skeletal muscle (isoenzyme M 4 ), under solvent conditions comparable to conditions in vivo, represents a stable, monodisperse tetramer. Solvent conditions which favour subunit dissociation on principle affect the native conformation of the enzyme leading to (pa…
Abstract Photochemical and thermal geometrical isomerizations of monoazo compounds have been studied in polystyrene– n ‐butylbenzene compositions. Cis–trans isomer ratios established by light absorption were found to depend on matrix viscosity. Where the compositions were above their respective glass temperatures, all…
Abstract p ‐Aminobenzoic acid and formaldehyde were condensed in the presence of acid catalyst. The linear condensation polymer thus obtained was then separated into four fractions by a fractional precipitation method. Conductometric titrations were carried out on these four polymer fractions and the conglomerate in n…
After a presentation of the theoretical background and experimental methods the data available for the paramagnetostriction of transition metals and alloys are surveyed and discussed, special consideration being given to the roles of exchange enhancement and orbital susceptibility. Attention is then turned to oscillat…
Fine particle size, high‐purity BaTiO 3 powder was used to fabricate sintered and hot‐pressed specimens. A second phase, BaTi 3 O 7 , frequently developed in samples fired at high temperatures. The dielectric properties of many specimens had frequency dispersions characteristic of interfacial polarization or other rel…
Abstract A new phenomenon in necking of some polymers, including poly(ethylene terephthalate) (PETP) was detected. It was found that extension of PETP films under certain conditions results in periodic stress oscillations and a periodic change in appearance of the sample. The conditions at which self‐oscillations appe…
Heterojunctions of nZnSe-pGe in which the ZnSe layer is thin and contains a considerable defect density exhibit switching between a high-impedance state of typically 106−107 Ω and low-impedance states three to five orders of magnitude lower, and have the ability to retain either state at zero bias for long periods of…
The optical spectrum and exchange splittings of the nearest-neighbor ${\mathrm{Cr}}^{3+}$ pairs in LaAl${\mathrm{O}}_{3}$ have been studied. The absorption and emission spectra of the $^{4}A_{2}^{4}A_{2}\ensuremath{\leftrightarrow}^{2}E^{4}A_{2}$ pair transitions from 7200 to 7600 \AA{} yield the ground-state exchange…
Abstract The helix‐coil transitions for poly( L ‐glutamic acid) (PGA) in 0.2 M NaCl and in its mixture with dioxane were studied by the methods of spectropolarimetry, viscometry, and potentiometric titration at different temperatures from 8 to 50°C. The enthalpy and entropy differences between the helical and coillike…