Materials Literature
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A technique for the preparation of pinhole-free glass films on porous substrates is described. The permeabilities of He, Ne, Ar, Kr, and D2 and the diffusivities of Ne, Ar, and D2 in the films are reported. The temperature range studied for He, Ne, and D2 was 25–500°C, while the range for Ar and Kr was 650–920°C. Acti…
Further evidence is presented to show that when cellulose is heated it undergoes two competitive reactions. The actual sequence of these is clarified, being different from that previously postulated. The natures of these reactions are studied, activation energies are determined, and their possible mechanisms are sugge…
The thermal conductivity of several NaF crystals of varying purity has been measured between 2 and 100 \ifmmode^\circ\else\textdegree\fi{}K. The full Callaway formalism is employed to derive phonon-phonon scattering rates from the thermal-conductivity data. The data can be fitted above 37 \ifmmode^\circ\else\textdegre…
A new electro-optical effect in twisted nematic liquid crystals is described which allows variation of the rotation of linearly polarized light continuously from 0° to 90°. It requires lower voltages than other electro-optic effects.
Abstract Für die Polymerisation von Lactid geeignete Initiatoren sind: Diäthylzink, Triäthylaluminium oder Zinntetrachlorid; folgende Verbindungen waren unwirksam: Triäthyloxoniumtetrafluobrat, Tropyliumtetrafluoborat, Tritylumhexachloroantimonat. Phenyldiazoniumhexafluophosphat oder Aluminiumtrichlorid. Die Polymeris…
Abstract The shape and forces of axisymmetric menisci have been calculated for sessile drops, pendant drops and liquid bridge profiles. The tables of Bashforth & Adams have been extended into the liquid bridge region by generating profiles beyond the 180° angle of their study, and into regions covered by a much wi…
Saturation magnetization was measured for a number of single crystals of hcp Co-base dilute alloys containing 3d-transition metal impurities such as Cr, Mn, Fe, Ni and Cu. The measurements were made with an induction magnetometer at 300 °K and 77 °K in fields up to 21 kOe in the directions of easy magnetization. The m…
Continuous-filament rayon yarns were subjected to an acid-catalyzed cross-linking treatment using dihydroxydi methylol ethyleneurea under pad-dry-cure conditions to two levels of add-on. The stress-strain curves of these yarns were measured at a constant 40%/min rate of extension in the dry (65% RH and 70°F) and wet s…
The magnetic properties of the spinels M1/2In1/2Cr2X4 with M = Cu or Ag and X = S or Se were investigated. In the sulphides the Cr spins order antiferromagnetically at TN = 40 °K for M = Cu and at TN = 17 °K for M = Ag. No spin ordering above 4 °K was observed in Cu1/2In1/2Cr2Se4, while Ag1/2In1/2Cr2Se4 is ferromagnet…
Powder neutron diffraction measurements have been performed on RbCoBr3. The results indicate that at TN = 36 °K, the compound exhibits a transition to an antiferromagnetic phase in which the spins are alternately aligned along c with a (+ + —) configuration for the three spins in the basal plane. This is in contrast t…
The magnetic moment of cobalt(II) fluorosulfate has been measured over the temperature range 312 to 120 °K and the results agree with theory for cobalt(II) in a regular octahedral ligand environment with λ equal to the free-ion value and no reduction in the magnetic moment due to electron delocalization. From its elec…
Expressions are developed for the orientation dependence of the nuclear quadrupole spin-lattice relaxation in crystals. Restrictions imposed by crystal symmetry are tabulated for the thirty-two nonmagnetic point groups. The possibility of distinguishing between different relaxation processes by means of orientation me…
PrCo5 D4-x(x= 0-,l à 0,3) haz been studied by neutron powder diffraction and by magnetization measurements on aligned powder specimens. The σ|| vs T curve shows a maximum at 50 °K. Above 50 °K the field dependence of the magnetization is small, below 50 °K it is large. In accordance with this, the magnetic structure a…
We discuss the magnetic behavior of rare earth systems where the crystal-field-only ground state of the rare earth ion is a singlet. As exchange increases in such a system, magnetic ordering at zero temperature occurs through a polarization instability of the singlet ground state. Such a process leads to a threshold v…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFormation of 16,16'-bisnorgeranylgeranyl pyrophosphate by farnesyl pyrophosphate synthetaseShuichi Seto, Tokuzo Nishino, and Kyozo OguraCite this: J. Am. Chem. Soc. 1971, 93, 3, 794–795Publication Date (Print):February 1, 1971Publication History Published online1 May 2002Pub…
An extended feasibility study was made of the use of the metalliding process to the application of highly impervious diffusion coatings on inexpensive conductive metals which normally corrode in acid electrolytes. Tantalum and hafnium, which proved highly corrosion resistant in acid media, are expensive for large scal…
The Ruderman-Kittel-Kasuya-Yosida (RKKY) exchange mechanism is examined for its relevance to ferromagnetism in the rare-earth metals. More specifically, the experimental sensitivity of the exchange energy (or Curie temperature) to the interatomic spacing (applied pressure) of the rare earths is examined in terms of th…
The interaction of ammonia gas, at pressures between 10−7 and 10−2 torr, with a polycrystalline tungsten filament, at temperatures between 200 and 700°K, has been investigated by thermal desorption mass spectrometry. Several procedures have been adopted to overcome the problems caused by the persistence of ammonia gas…
The magnetization and the susceptibility of isostructural compounds (6Mn23-structure) of the composition RE6(MnxFe1-x)23(RE = Y, Gd) have been determined from 4 °K to 1 200 °K. The Curie-temperatures Tc of the RE6Mn23 and the RE6Mn23 compounds (RE = Y, Gd) are in the range from 468 °K to 486 °K. In the case ofY6(MnxFe…
Some of the sources of hairiness of cotton yarns and their blends are investigated. The influence of fiber parameters, spinning process, and yarn parameters are discussed. Also, some contradictions found in the literature in connection with certain aspects of the influence of these parameters on hairiness are clarifie…