Materials Literature
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Abstract The compositions of copolymers formed by reacting styrene or α‐methylstyrene (M) with lithium in tetrahydrofuran in the presence of varying amounts of alkyl dibromides (RX 2 ) have been studied. Regular copolymers of structure are formed at 2:1 monomer to dibromide molar stoichiometry, but they become less re…
Electron diffraction patterns having 3500 reflections out to 2 angstromns were obtained from wet microcrystals of catalase. No diffraction was obtained if the water vapor pressure was set below 90 percent of the equilibrium value.
Brief information is presented on the composition and properties of high-strength steels. Questions of their weldability are discussed, modern concepts of the causes and mechanism of cold and hot cracking are set forth and ways of preventing them are suggested. Information about the properties of weld joints, welding…
We have found that the substitutional replacement of Ti for Ta in Ta${\mathrm{S}}_{2}$ stabilizes the octahedral $1T$ phase for $x$ between 0.1 and 0.9. A comparison of the resistivity, magnetic susceptibility, and thermoelectric power shows that at room temperature the properties vary systematically from diamagnetic,…
An interpretation is given of the anisotropic chemical shift of the 59Co NMR line in a single, four-layer orthorhombic crystal of K3Co(CN)6 in terms of the digonally distorted octahedra of CN ions surrounding a cobalt ion. The various possible sources of contributions to the electric field gradient tensor (EFGT) at a…
The increase of the dislocation density during plastic deformation in high-pure and nickel doped copper single crystals, which was determined quantitatively by etching of emerging screw dislocations, is primarily dependent on the effective shear stress. An influence of the basic structure on the work-hardening charact…
An acoustic modulator using a liquid crystal and a piezoelectric driver is described. The response time of the modulator is less than the time needed for the onset of mechanical stress. Actually it is governed only by the electromechanical properties of the piezoelectric driver used.
Isolates from four sites were identified as varieties of the diatom Gomphonema parvulum Kütz. The material was examined by light and electron microscopical techniques. A detailed account of the morphology of this species is given. No fundamental differences between the varieties were found apart from cell shape. It is…
The seasonal succession of algal species in the epipelon of two small pools over a period of three years is described in relation to changes in silica, nitrate-nitrogen and phosphate-phosphorus concentrations in the water above the sediments. Recurring patterns of seasonal growth of the various species are discussed.
The diagrammatical method for the calculation of the matrix elements of an arbitrary spin-independent operator in the basis of single antisymmetrized geminal products, developed in Part I, is applied to derive the overlap and energy mean value expressions for various types of geminal wavefunctions, namely for strongly…
The scanning electron microscope has provided much information about the structure of the valves of centric diatoms that supplements or, at times, corrects the accounts based on transmission electron microscopy. In particular, the morphology of the special features that have been called processes, spines, ocelli, tubu…
In order to determine quantitative information about chemical bonding in metallocenes, we investigated the electronic structure of the cobaltocene molecule by EPR and magnetic susceptibility measurements at 4.2°K and by optical spectroscopy at 77°K. Diamagnetic ruthenocene, weakly paramagnetic nickelocene, and paramag…
The relative emission per ion and the lifetime have been obtained as a function of Tb concentration for the $^{5}D_{4}$ to $^{7}F_{J}$ transitions in ${({\mathrm{Y}}_{1\ensuremath{-}x}{\mathrm{Tb}}_{x})}_{3}{\mathrm{Al}}_{5}{\mathrm{O}}_{12}$ crystals. At 297 \ifmmode^\circ\else\textdegree\fi{}K both are concentration…
${\mathrm{Cd}}_{2}$Sn${\mathrm{O}}_{4}$ has been found to be an $n$-type defect semiconductor in which oxygen vacancies provide the donor states. Crystalline powders and amorphous films with a wide range of conductivities have been prepared. Large Burstein shifts have been observed in the visible reflection and transm…
The photoelectron spectra of some 40 transition metal compounds have been measured using AlKα(1487 eV) and MgKα(1254 eV) x-rays. The compounds included both simple salts (halides and chalcogenides) and hexacoordinated complexes (cyano- and fluoro-) of Cr(III), Mn(II, III), Fe(II, III), and Co(III). From these data we…
Abstract La synthèse de spiropyrannes photochromes substitués en position 3 montre que la méthode de cyclisation classique est limitée dans certains cas, notamment pour les composés multifonctionnels ou lorsque les anhydrobases intermeAdiaires sont peu réactives; elle constitue en mêmo temps une généralisation de la s…
Abstract An X‐ray crystal structure investigation of the macrotetrolide antibiotic nonactin is reported. The shape of the molecule is discussed with special reference to the conformational changes involved in passing from free nonactin to the K + ‐complex.
Results on the temperature dependence of orientational order at constant molar volume in the nematic liquid crystal $p$-azoxyanisole are reported for the first time. These results clearly indicate the failure of theories of the nematic phase which do not include both energetic and steric intermolecular interactions.
Abstract The ‘observed’ π‐orbital energies ϵ v,j = −I v,j derived from the vertical ionization potentials obtained by a photoelectron spectroscopic investigation of the acenes benzene A(1), naphthalene A(2), anthracene A(3), naphthacene A(4) and pentacene A(5) have been compared with π‐orbital energies calculated by t…
This paper treats the derivation of a two-dimensional differential equation, which describes the phenomenon of combined refraction — diffraction for simple harmonic waves, and a method of solving this equation. The equation is derived with the aid of a small parameter development, and the method of solution is based o…