Materials Literature
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The consequences of ]-refinement procedures on atoms whose charge distributions are intrinsically non-centrosymmetric are examined in terms of a simple hypothetical structure consisting of two sp a hybrid valence 'prepared' state nitrogen atoms which are centrosymmetrically disposed in a unit cell and asstuned to be v…
Optical absorption and thermoluminescence measurements on untreated crystals of magnesium oxide have shown that the crystals can be divided into two groups. X irradiation of the crystals induces an optical absorption peak at 2.3 ev in group I crystals and at 2.3 and 3.0 ev in group II crystals. Thermoluminescence curv…
The temperature dependence of breakdown field, distribution of time lag. and dielectric constant in high electric field were studied on polycrystalline BaTiO 3 . The d. c. breakdown field is nearly constant in the temperature range 20 to 150°C, on the other band the pulse breakdown field changes markedly near the Curi…
This paper is composed of three parts: 1 Apparatus and method for determination of heat transfer through fabric during flame contact; 2 experimental validation of mathematical analysis and heat flow; 3 application to determination of thermal properties of materials in thin layers.
A phase diagram of the system MnSi-Si containing Si in the range from 45.00 to 57.00 wt% is determined by the methods of X-ray, metallographic and thermal analyses and also by the electrical measurements. It is found that the intermetallic compound in this system is MnSi 1.72 . This compound has the maximum melting po…
Thermal expansion, ultrasonic and creep behavior of polytetrafluoroethylene are studied in temperatures from -100° to 180°C. The glass transition and primary dispersion of this polymer observed. The assignments of relaxations and transitions described in what follows are found to be quite compatible with experimental…
The various components of the stress-fields of piled-up groups of screw and edge dislocations are calculated by replacing the array of discrete dislocations by a continuous distribution. The stress-fields are resolved onto each of the eleven secondary systems of the face-centred cubic lattice; by mapping out the stres…
Intergranular cracking tendencies of fourteen stainless steels and two high-nickel alloys have been evaluated by exposing numerous specimens to polythionic acid and standard acid copper sulfate solutions. The sensitization curves for solution-annealed wrought stainless steels, which had been held for varying times at…
Crystals, needles, ribbons, and platelets, grown from pure and impurity-added CdS vapor, have been studied morphologically. Needles grow parallel to the [0001], [101̄0], and [21̄1̄0] axes of the hexagonal system. Ribbons grow parallel to the [101̄0] and [21̄1̄0] axes and their surfaces are parallel to the (12̄10) and…
The stress fields of edge dislocation dipoles are able to trap other edge dislocations that pass nearby. The configurations, energies, and trapping stresses of the resulting tripoles are discussed here in some detail. Dipoles may also interact dynamically with approaching dislocations because they cause fluctuating st…
The structure of α-N2 is cubic in the space group P213 with four molecules per unit cell. A total of 49 independent observed single-crystal x-ray diffraction maxima yield R=Σ ‖Fo|−|Fc ‖ /Σ|Fo|=0.13. Two faint reflections, (501) and (520), violate the space group Pa3, which yields R=0.21. Molecular centers are displace…
Abstract An amorphous polymer is characterized as a homogeneous array of N identical, n ‐center polymer segments which can be described in terms of four molecular constants. A mechanism for viscous flow (or self diffusion) is visualized as a positional exchange of two adjacent polymer segments in a hole the size of a…
Abstract 1) The reaction of 1-ethoxy-n-heptyl hydroperoxide with ferrous sulfate has given ethyl formate, n-heptanal, ethyl heptanoate and n-dodecane, while the reaction with a mixture of cuprous and cupric chlorides has given ethyl formate, n-hexyl chloride, n-heptanal and ethyl heptanoate. 2) The formation of n-hept…
Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation R. E. Pawel; Procedure for Stripping Anodic Oxide Films from Tantalum and Niobium. Rev Sci Instru…
The borates were prepd. by heating the metal oxides, halides, and H3BO3 in a sealed quartz tube. Structures were deduced from x-ray powder diagrams.
Conduction in single crystal and ceramic BaTiO3 has been investigated using a concentration cell and activation analysis. Ionic conduction occurs near 100°C in single crystals containing Fe2O3 while electronic conduction predominates in ``pure'' crystals from 100° to 600°C. Ceramic samples conduct predominately ionica…
e theory of the Raman scattering by crystals is discussed and detailed calculations made of the spectra from sodium iodide and potassium bromide. Expressions for the dependence of the optical polarizability on the normal modes of vibration are obtained by using the shell model with anharmonic interactions between the…
Abstract The morphology of linear polyethylene crystallized under pressures up to 5300 atm. has been investigated. Electron micrographs of fracture surfaces obtained from these samples show that the majority of the polymer, at the highest pressures, crystallizes in the form of extended chain lamellae which can be as t…
SUMMARY The structure of the galactohinase in Escherichia coli has been analyzed with the aim of defining the size of its structural gene. To that end the molecular weight, amino acid composition, number of tryptic peptides, and amino-terminal residues of this protein were determined. The results indicate that this ga…
A number of programs for facilitating the indexing of powder patterns, based essentially on trial-and-error methods, have been constructed for the electronic computers BESK and Facit EDB. The methods are efficient also for the analysis of powder patterns in which lines are missing either by accident or because of tran…