Materials Literature
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It is pointed out that the recent observation of localized holes and electrons at low temperatures after optical excitation of chalcogenide glasses by Bishop et al. is consistent with a model previously proposed for lone-pair amorphous semiconductors. The model uses the existence of these localized states to provide a…
Abstract Mit Hilfe der Röntgendiffraktometrie werden die Phasengleichgewichte des Systems MgO ‐MgC12 ‐ H 2 Obei 25°C sowie die Reaktionen, die zur Bildung der Gleichgewichtsphasen 5 Mg(OH)2°C MgClg ° 8 H 2 O und 3 Mg(OH)2°C MgClg ° 8 H 2 O führen, untersucht.
From light scattered by director modes in the smectic-$A$ phase of cyanobenzylidene octyloxyaniline (CBOOA) and octyloxy cyanobiphenyl (80CB) we deduce that the restoring force for phase fluctuations in the smectic order parameter vanishes as ${({T}_{c}\ensuremath{-}T)}^{0.33}$ as the nematic phase is approached. In C…
Abstract Thermolysis of p-acetylphenyl 3-guaiazulenecarboxylate (1) results in loss of the ester group. In contrast, thermolysis of phenyl 3-guaiazulenecarboxylate (2) or p-methoxyphenyl 3-guaiazulenecarboxylate (3) gives (i) loss of the ester group, (ii) loss of the 1-methyl group with concomitant rearrangement of th…
A new stylus with which it is possible to measure both the steep and shallow sides of diffraction grating grooves is described. The relations between the ruling tool profile and the groove profiles have been investigated and it is shown that the included angle of grating grooves may be considerably less than that of t…
A device is described which illustrates how physical principles learned in the classroom can find industrial application. This device is the thermoelectric metal sorter which operates on the principle of the Seebeck effect.
The thermal decomposition of dialkyl tert-butylperoxy phosphates, in the presence and absence of solvents, yields the corresponding dialkyl phosphate, acetone, methanol, 2,2-dimethoxypropane, and methyl isopropenyl ether as the primary products. Prolonged heating of the product mixture produces trialkyl phosphates, (R…
Nuclear spin relaxation-time measurements of the cesium nuclei in the perovskite crystal CsPb${\mathrm{Cl}}_{3}$ are reported for the temperature range 300-430 K. The data exhibit the characterisitic anomaly which is expected to occur in the civinity of the structural phase transitions. Comparison of these data with c…
Analytically pure single crystals of polymeric sulfur nitride (polythiazyl), (SN) x, suitable for solid state studies were prepared by the spontaneous room temperature polymerization of single crystals of pure S 2 N 2 . The polymer is relatively inert to oxygen and water. A single-crystal x-ray study revealed that an…
Electrothermal atomic absorption spectrometry has five major advantages for measurements of trace metals in biological materials, in comparison to measurements by conventional flame atomic absorption analysis: (1) Trace metal contamination is minimized by avoidance of preliminary chemical extractions and additions of…
The production of light upon the electron transfer reaction of electrogenerated radical ions of tetraarylpyrroles [aryl = anisyl (TAP), phenyl (TPP), tolyl (TTP), p‐chloro‐phenyl (TCPP)], tetraphenylfuran (TPF), and tetraphenylthiophene (TPT) in systems containing these compounds alone in acetonitrile solutions or in…
High-speed streak and framing photography of surface flashover across solid insulators in vacuum is reported. Experiments were performed with direct and impulse voltages. It is shown that the initial propagation of a visible arc across an alumina surface in vacuum occurs at a speed greater than 109cm . s-1. It is show…
This paper presents a progress report on a continuing investigation into the voltage endurance of cast and molded resins, particularly cast epoxy resins. The relation of gas cavity size to the observable discharge magnitude and the stress level on the resin at which discharges can be expected to occur within internal…
Abstract As a preliminary step to studies on the regeneration of active carbon, its wet oxidation has been followed in order to obtain information about the different parameters involved: agitation, temperature and pressure. The oxidation reaction takes place in the liquid phase and it does not proceed at significant…
The detection of centre of symmetry is a problem of great importance in the determination of crystal structures by X-ray methods, and not always solvable by these methods alone. Generation of a second harmonic at optical frequency is governed by coefficients which are zero for all centrosymmetric point groups and 432,…
The transient hot-wire method was used to determine the effect of fillers on the thermal conductivities of different rubbers in the pressure range up to 0.2 GPa at 300 K. The fillers, carbon black and ZnO, both strongly increase the absolute conductivity values but the relative pressure reponses are only slightly affe…
The saturation velocity of electrons in n-GaAs has been deduced from the v/E characteristic over a temperature range 130-400 K. The experimental values are compared with those predicted by a model assuming the velocity to be limited by intervalley scattering in the (100) valleys. The agreement between theory and exper…
ATJ-S graphite is a transversely isotropic granular composite material with different nonlinear stress-strain behavior under tension loading than under compression loading. A model for nonlinear deformation behavior is extended from initial loading under biaxial tension stresses to initial loading under mixed tension…
Three austenitic stainless steels (AISI 304, 304L, and 316) were solution-annealed at 1350 К (1975 F) and water-quenched. Specimens were subsequently cold-upset forged to various degrees of cold reduction, with tensile and corrosion test specimens machined out. Corrosion specimens were exposed to boiling 65% nitric ac…
The synthesis and antiallergic activity of a number of benzodipyrandicarboxylic acids are described. Antiallergic activity of the compounds was determined using the homologous passive cutaneous anaphylaxis (PCA) reaction in the rat. The structural requirements for activity in the PCA screen are discussed. In this test…