Materials Literature
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N.m.r. spectroscopy is used to demonstrate that the predominant interaction in aggregations of magnesium(II) porphyrins [e.g.(1)] involves the metal atom in one molecule and the propionate carbonyl group in another; in contradistinction, the similarly strong aggregation observed for the first time in zinc(II) porphyri…
The areal detection efficiency of a channel electron multiplier array (CEMA) and the nature of its secondary emission surface were investigated with the ion microprobe mass analyzer (IMMA). Previous speculations of detection efficiency based on simple geometric arguments of channel-to-interchannel area ratios are show…
The equilibrium vapour pressure of barium carbonate and the vacuum decomposition rates of the (001) face of its single crystal were measured by torsion–effusion and torsion–Langmuir techniques, respectively. The rate of the free surface decomposition reaction was constant for product layers up to about 1 mm thickness.…
G. M. Clark and R. Morley, Chem. Soc. Rev., 1976, 5, 269 DOI: 10.1039/CS9760500269
M. C. R. Symons, Chem. Soc. Rev., 1976, 5, 337 DOI: 10.1039/CS9760500337
Refractive indices of a mixture of nematic liquid crystals as functions both of wavelength and applied voltages were measured. The measured results are compared with a theoretical calculation in which first the distributions of tilt angle of the molecules were computed by solving a reorientation equation, then, the ef…
Всегда ли справедливы соотношения Крамерса — РљСЂРѕРЅРёРіР° для диэлектрической проницаемости вещества?, Киржниц Р”.Рђ.
Creep deformation of 0° sapphire was studied between 1600°and 1800°C at stresses up to 114 MN/m 2 . Microscopical evidence (dislocation structures observed by transmission electron microscopy (TEM) and by etch pits) suggested that Nabarro climb was the predominant deformation mechanism. Both the experimental creep rat…
Raman spectra of powdered samples of tungsten trioxide have been obtained over the temperature range 80–300 K. No discontinuous or major changes in the spectra are observed, indicating that the transition at 233 K to the ferroelectric phase is inhibited for this form of sample, presumably because of perturbations to t…
A purification of over 2000-fold is reported for collagen glucosyltransferase from Triton X-100 extract of whole chick embryos and one of about 160-fold from similar extract of chick embryo cartilage. The addition of the detergent more than doubled the enzyme activity in the homogenates. The purified enzyme preparatio…
Abstract The rate of decomposition of t ‐butyl nitrite (TBN) has been studied in a static system over the temperature range of 120–160°C. For low concentrations of TBN (10 −5 ‐ 10 −4 M ), but with a high total pressure of CF 4 (∼0.9 atm) and small extents of reaction (∼1%), the first‐order homogeneous rates of acetone…
Measurements of the thermal and electrical conductivity and thermopower of very pure copper and silver have been made between 1 and 8.5K. The copper samples have been distilled in graphite crucibles to reduce the concentration of magnetic impurities to less than 1 part in 10 9 , which is an order of magnitude improvem…
An alternative derivation is presented of the equation for the equilibrium contact angle between a gas, a liquid and a plane solid surface. The excess free energy of the system around the contact line is minimized with respect to the contact angle θ0 at constant surface area. Thus the surface tension (or surface free…
The physical structure of the melt, the supercooled melt, and the glassy state of amorphous polymers can be characterized by the chain conformation, the local order, and the morphology. The conformation was studied by small-angle neutron scattering. The local order was characterized by pair distribution functions whic…
Stress-strain and relaxation tests were performed in air between—196°C and +80°C, and in methanol and silicone oil at room temperature on linear polyethylene hard elastic fibers. Transmission electron microscope observations of similarly deformed specimens indicated that straining resulted in fibrils connecting separa…
The strength of aggregation in PdII, NiII, ZnII, and CdII metalloporphyrins is shown by n.m.r. spectroscopy to depend upon interaction of the metal ion with the porphyrin π-system; within a selected series of 2,4-disbustituted deuteroporphyrin-IX dimethyl esters complexed with a constant metal ion the aggregation is f…
Abstract Previous work on the effects of crystallinity on the autoxidation of polyolefins is briefly reviewed and shows that polyethylene and polypropylene oxidize exclusively in the amorphous phase. Measurements of the rate of oxidation of poly(4‐methyl pentene‐1) (P4MP) show that the oxidation is first‐order in oxyg…
Abstract not Available.
For a ferroelectric in form of a thin plate with the polarization perpendicular to the surfaces it is demonstrated that for the ferroelectric state to be stable the polarization discontinuity must be compensated by free charge. In thermal equilibrium the charge compensation can never be complete. Depolarization fields…
Relations have been derived from gas analyses of irradiated PyC‐coated UO 2 fuel particles that enable the quantity of permanent rare gas (Xe+Kr) released within the particle to be predicted from known conditions of irradiation temperature, time, and burnup. The experimentally determined influence of fissions in urani…