Materials Literature
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The Néel theory of the approach to saturation in inhomogeneous magnetic materials is critically reviewed. It is found that the theory is rigorously applicable when the local saturation magnetization differs only slightly from its spatial average, but that this condition is not satisfied in porous materials or in mater…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIntramolecular quenching of the excited singlets of phenyl .omega.-dialkylaminoalkyl ketones. Singlet state type II photoelimination of .alpha.-dimethylaminoacetophenonePeter J. Wagner and Thomas JellinekCite this: J. Am. Chem. Soc. 1971, 93, 26, 7328–7330Publication Date (P…
Energy and charge transport by secondary electrons across interfaces between gamma irradiated materials can be important for accurate predictions of radiation effects. In order to measure these charge transport effects air ionization and secondary electron emission currents were observed in a multiple cavity aluminum…
D.C. electric-field-induced pitch contraction and a simultaneous transition from the cholesteric plane texture to the focal conic texture were studied microsopically in a mixture of 20% cholesteryl chloride and 80% cholesteryl oleyl carbonate. The texture change is preceded by the formation of a periodic pattern in th…
Records of occurrence of 12 rare species of the genus Amphora in the Laurentian Great Lakes are given. Five of the taxa discussed are reported as new and five are reported for the first time from North America. Presently known distribution and abundance of these entities is presented and apparent similarities with the…
Gassy and degassed aqueous solutions of DNA were treated ultrasonically while monitoring the field for discrete cavitation events. At irradiation intensities greater than about 500 W/cm2, transient cavitation is shown to be responsible for the observed reduction in molecular weight. At intensities of 200 to 288 W/cm2,…
Abstract Previous studies of the line profiles of the basal reflections of microcrystalline muscovites were refined by an adaptation of the method developed by Maire and Méring. In order to evaluate the variation of interlayer spacings, the method required only relative values of Fourier coefficients, without the corr…
The theory of multiple small-angle scattering is revised and extended to systems of arbitrary symmetry and structure. The principal difference between the evaluation of multiple scattering with and without observable primary beam is discussed and the values of the parameters related to the limits between single scatte…
Narrow-band luminescence from rare-earth centers in zinc sulphide powders has been observed with medium-voltage direct-current excitation for five rare-earth-doped zinc sulphide phosphors. The brightness and powder efficiencies have been measured and the electroluminescent spectra obtained show differences from the ph…
Abstract More than twenty new organic complexes of halloysite have been prepared and one hundred and twenty-seven compounds were tested. Results are compared with those of earlier studies and use is made of recent findings concerning particle morphology and interstratification effects to interpret the results. The com…
Abstract It is shown that the glass transition temperatures of the ionic acrylates are subject to the same correlation as found for the phosphates, silicates, and ionenes; the equation is T g = 730 ( q/a ) − 67, where q is the cation charge and a the separation between centers of charge for the cation and anion.
A thermodynamic and high‐temperature X‐ray diffraction study was performed on polycrystalline nonstoichiometric BaTiO 3 . The oxygen composition was measured from 940° to 1215°C at O 2 partial pressures between 10 −10 and 10 −21 atm by a thermogravimetric technique. The isothermal weight change data exhibit a two‐slop…
The extensional moduli and Poisson's ratios of cold-drawn low-density polyethylene sheets have been determined by direct observation of the changes in dimensions under load of electron microscope grids printed on the surfaces of the sheets. The highly drawn sheets show incompressible behavior only for vanishingly smal…
Abstract Nach einem kurzen Überblick über bisherige Untersuchungen an Epoxidharz–Dizyandiamid‐Systemen, wurde der Reaktionsverlauf eines handelsüblichen dizyandiamidhärtenden Epoxidharzes mittels Ultrarotspektroskopie verfolgt und mit den Ergebnissen früherer anderer Methoden am gleichen System verglichen. Dabei ergab…
Abstract Die Infrarot‐ und Ramanspektren von Thioharnstoff‐Einkristallen bei 300 und 120°K werden mit polarisierter Strahlung aufgenommen. Zusätzlich werden die Spektren der deuterierten Verbindung an polykristallinen Proben und die Fern‐Infrarot‐Spektren an pulverförmigen Proben gewonnen. Damit ist eine vollständige…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSelf-consistent-field wave functions of P2 and PO, and the role of d functions in chemical bonding and of s-p hybridization in N2 and P2Robert S. Mulliken and Bowen LiuCite this: J. Am. Chem. Soc. 1971, 93, 25, 6738–6744Publication Date (Print):December 1, 1971Publication Hi…
Abstract The small‐angle light scattering (SALS) theory for optically anisotropic spheres and disks is examined in depth. An error is found in the existing sphere equations. The correct form of the equations is identified and then experimentally verified for dilute starch suspensions. Increased concentrations and soli…
Abstract Li-, Na-, K- and Ca-saturated Wyoming montmorillonites have been prepared and used to obtain Li,Na-, Li,K-, and Li,Ca-montmorillonites with a range of Li contents. These were heated at 220°C for 24 hr, causing the Li + ions to migrate mainly into the layer structure and leaving varying amounts of Li + , Na +…
The dislocation arrangements in single crystals of Cu 2% at. Al and Cu 10% at. Al deformed into stage II of the work-hardening curve have been observed by transmission electron microscopy. The observations are described and discussed in relation to the theories of stage II work-hardening. It is concluded that the beha…
The drift of charge carriers in thin vitreous films of arsenic triselenide has been examined by a transit time technique. The specimens used were prepared by cooling from the molten state, rather than by evaporation. Electron mobility measurements were found to be impractical, the mobility being estimated as less than…