Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSilyl ketone chemistry. A new regiospecific route to silyl enol ethersHans J. Reich, Jay J. Rusek, and Richard E. OlsonCite this: J. Am. Chem. Soc. 1979, 101, 8, 2225–2227Publication Date (Print):April 1, 1979Publication History Published online1 May 2002Published inissue 1…
Abstract The transformation of a spun isotactic polypropylene fiber into a high strength elastic fiber has been followed structurally. By examining each stage of the transformation separately, it has been possible to identify the different structural mechanisms that occur as the process proceeds. The recognition of th…
Introduced in a one-electron self-consistent model (D–C field perturbated INDO Hamiltonian), symmetry considerations exhibit σ and π electron contributions to second order polarizabilities of planar molecules. A family of benzene monosubstitutes is explored, their mesomeric moments and π second order hyperpolarizabili…
Pitting potential measurements have been made by potentiostatic, potentiokinetic, and scratch test methods. Several surface conditions were tested to determine the relationship between test methods, surface condition, and experimental procedure on both base and weld metal. The results indicate the complex interrelatio…
Abstract The relaxation following a change in temperature of amorphous polymers near the glass transition has been calculated. The calculation uses a chain model consisting of cis and trans backbone rotational states. The relaxation is assumed to proceed by localized conformational changes whose rates are controlled b…
Local atomic arrangements were investigated as a model of amorphous iron in terms of Voronoi polyhedra for a dense random packing of hard spheres with and without relaxation. The structure of liquid iron was also simulated in a computer. The amorphous structure was microscopically described as a mosaic of crystalline…
We summarize the results of high resolution X-ray and light scattering studies of the smectic A-nematic transition in cyanobenzylidene-octyloxyaniline, octyloxy-cyanobiphenyl, and octyl-cyanobiphenyl. Pretransitional behavior in the nematic phase is essentially consistent with the He4 analogue proposed by de Gennes wi…
Within the context of gas chromatography, pyrolytic methylation can be defined as the process whereby a volatile methyl derivative of an acidic compound is formed within the injector block of a gas chromatograph by the thermal decomposition of a quaternary N-methylammonium salt of the acid. The methyl derivative and t…
Following experimental studies on benzene substitutes, we have attempted to derive some results on their molecular hyperpolarizabilities from a semiempirical treatment of the Hartree–Fock equations extended to all valence electrons (INDO procedure). The INDO equations are modified so as to introduce a dipolar perturba…
The fracture strength of two kinds of UO2 specimens possessing pores of different maximum sizes (60 and 140 μm) was measured in the range of room temperature − 1,300°C by means of diametral compression testing. The fracture strength thus obtained proved to be smaller than any of the values reported by previous authors…
Recent measurements of nematic-smectic A pressure-temperature phase boundaries obtained in bilayer forming smectic A liquid crystals are analyzed. A thermodynamic model which accounts for the elliptical shape of the phase boundaries and which facilitates determination of the various parameters determining the phase bo…
Liquid metal in a closed container made of dissimilar metal under a magnetic field is, in general, set into motion by thermoelectric effects if the interfacial temperature is nonuniform, a situation likely to occur in fusion reactor blankets owing to the high thermoelectric power of lithium. The paper sets out the gen…
Expressions are derived for the discharge inception voltage (Vi), at which discharges occur in entrained voids within the insulation of single-core cables. The influence of Vi on the shape, and location of a void has been determined for different air pressures inside the void.
The various aspects of the use of boron products in cellulose insulation are discussed.
Phosphate deposits of igneous origin contributed some 19 million metric tons to the total world marketable output of phosphate rock of nearly 116 million metric tons in 1977. Most of this was produced in the USSR from the Khibiny Complex, Kola Peninsula. There was production at the neighboring Kovdor Complex and, in n…
A series of experiments was done to determine how contamination flashover occurs under dc conditions. It was found that polarity influenced the flashover voltage, with flashover occurring more readily for negative polarity. Several reasons are advanced to explain this, including cathode spot phenomena, and electrochem…
Abstract Polarized Raman spectra of single crystals of NaH 2 PO 4 ·2H 2 O and NaD 2 PO 4 ·2D 2 O have been measured as a function of temperature in the wavenumber shift range 10–3600 cm −1 . Changes of phonon frequencies due to directional dispersion are found. All the observed bands have been assigned using group the…
Al-coated glasses of molar composition 20Na2O-10CaO-70SiO2 have been bombarded with a rastered beam of either 7- or 10-keV electrons. SIMS analysis of these glasses indicates a near-surface layer deficient in Na, bounded by a steep rise of the Na signal. The thickness of this layer increases with electron-bombardment…
Abstract Ag 2 BaGeS 4 was prepared for the first time and the crystal structure determined using X-ray methods, a - b = 682,g; c = 801, 7 pm, Space group I4̅2 m (No. 121) tetragonal. The atomic parameters and interatomic distances are reported and the structure is discussed.
The doping method in quantitative X-ray diffraction phase analysis is described. The method involves the addition to the investigated system of known amounts of the components, the weight fractions of which are to be simultaneously determined. The weight fraction of a component is related to the intensities diffracted…