Materials Literature
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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…
A complex set of forces, both external and internal, governs the movements of nutrients through the environment. The circulation of mineral elements can be modeled as a system of compartments and transfer pathways. A simple version of this model has two valuable pedagogical uses. First, the idea of an equilibrium mine…
Measurements in a rectangular channel of the three viscosities η1, η3, η2 for laminar flow with the director parallel or perpendicular to the velocity or homeotropic orientation respectively, are reported for 4-n-octyloxy-4-cyanobiphenyl. In the nematic range, η1 has a pronounced divergence near the nematic/smectic tr…
Various correlation functions appearing in the theory of vibrating substitutional alloys with an arbitrary concentration of defects, including mass disorder as well as force-constant changes are calculated. The force-constant matrix is chosen such that the formalism of the locator-CPA can be applied to calculate the c…
It is proven that under suitable assumptions the change of symmetry associated with the bifurcation from the axisymmetric Maclaurin to the triaxial Jacobi ellipsoids can be described as a second-order phase transition in the entropy-volume plane. The proof is given by showing explicitly that the value of the eccentric…
Two series of novel methylene-bridged liquid crystals have been prepared. These molecules are quite wide and as a result only higher homologues exhibit mesomorphism. The enantiotropic mesophases are of the smectic C type. Trends in thermal behavior of these two series indicate that even higher homologues should posses…
The smectic properties of four series of esters — the methyl to n-decyl esters of the 4'-n-hexyloxy, 4'-n-heptyloxy-, 4'-n-octyloxy- and 4'-n-nonyloxy-biphenyl-4-carboxylic acids — are discussed. The effects on the smectic phases of increasing the alkyl chain lengths are quite striking, particularly in the last three…
Type material of Thalassiosira minuscula Krasske and material identified by the respective authors as Nitzschia delicatissima Cleve and Cyclotella nana Hustedt (= Thalassiosira pseudonana Hasle et Heimdal) have been examined in light and electron microscopes. It is suggested that the slide labelled “Nitzschia delicati…
Polyurethanes based on diphenylmethane 4,4′-diisocyanate (MDI) were examined by electronic spectroscopy and by continuous and laser flash photolysis. Fluorescence and phosphorescence emissions were observed, and although the source of the fluorescence could not be identified, the phosphorescence appears to originate f…
The general rule that addition of a non-mesogenic solute causes a sharp decrease in the nematic-isotropic transition temperature (TN→ I) of a nematic solvent is not obeyed when the solute and solvent can enter into a donor-acceptor interaction. Addition of 4-aminobiphenyl to the nematic liquid crystal 4-cyano-4′-penty…
Abstract Data on the Raman spectra of natural α‐Glycine and 15 N‐substituted α‐Glycine are presented together with details of a computer calculation of the normal vibrations. Assignments are made and compared with previous assignments based on IR measurements.
Magnetic measurements and metallographic investigations are reported on Sm(Co,Cu)z alloys. The compositions lie between the rare-earth (RE) to transition-metal (TM) ratios of 1 : 5 and 2 : 17 with a content of copper of up to 35% of the TM fraction. The materials were analyzed both in the as-cast and heat-treatment co…
Summary Apjohnite, MnAl 2 (SO 4 ) 4 ·22H 2 O, is monoclinic, space group P2 1 /c, a 6·198 (2), b 24·347 (4), c 21·266 (4) Å, β 100·28 (3)° and Z = 4. The crystal structure was determined by means of direct methods applied to X-ray data collected with a single-crystal diffractometer. At the end of the refinement, perfo…
A capillary dilatometer has been automated by means of a capacitive transducer technique. The precision is 1 : 105 over a range in volume of 4% for a sample volume of 2 ml. Differential scanning dilatometry is achieved by comparing the sample dilatometer with a reference dilatometer. Some results for the density chang…
The effect of aging on the microstructures of Sm-Co-Cu alloys is reported. It is shown that small precipitates are present within the SmCo5-type phase in as-cast material. On aging below 650 °C these precipitates are exceptionally stable, but at 800 °C they coarsen rapidly. These results are rationalized in terms of a…