Materials Literature
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Abstract Die ternären Selenide Rb 3 Cu 8 Se 6 und Cs 3 Cu 8 Se 6 konnten durch Umsetzungen von Alkalimetallcarbonaten mit Kupfer und Selen in der Schmelze synthetisiert werden. Röntgenbeugungsuntersuchungen an Einkristallen führten zur Struktur der isotypen Verbindungen. Die monoklinen Elementarzellen enthalten zwei F…
Polygonal defect arrays in lipid liquid crystals prepared from dipalmitoyl-, dimyristoyl-, and dilaurylphosphatidylcholine with various concentrations of water have been observed and characterized using optical microscopy. These arrays appear similar to the polygonal arrays previously observed in thermotropic smectic…
Abstract The most important techniques of those currently used in Home Office forensic science laboratories for the analysis of fiber dyestuffs are thin-layer chromatography and visible absorption spectroscopy of dye solutions. To obtain useful discrimination 20 to 50 ng of each dye component must be extracted. In mos…
Mono and diesters of itaconic acid have been pi'epared using linear , branched or cyclic alkane structures . These have been homo and copolymerized to produce a wide range of polymers with differing properties. These range from polyacids to polydiesters to ionomeric structures. Their physical behaviour has been examin…
A review of six years operational experience in using the slow strain test procedure has indicated several unique advantages associated with dynamic strain techniques and also identified an area of limitation. The chief advantage of the dynamic slow strain test procedure is that it is much more aggressive in producing…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructural Selectivities in the Reduction of Poly(vinyl chloride) with Lithium Aluminum Hydride and Tri-n- butyltin HydrideW. H. Starnes Jr., F. C. Schilling, K. B. Abbås, I. M. Plitz, R. L. Hartless, and F. A. BoveyCite this: Macromolecules 1979, 12, 1, 13–19Publication Dat…
A V.G. Microscopes' HB5 STEM has been used to study a segregated copper-bismuth alloy. It is shown that the Z contrast mechanism due to Crewe (1970 a, b) is not valid for such crystalline materials. Attempts to use the energy loss spectrometer, with which the microscope is fitted, to detect the bismuth spectrum from t…
We study in detail the defect structure observed in a cylindrical geometry near the smectic A-cholesteric transition. The orientation of the molecules at the capillary surface is radial. We propose that the cholesteric phase grows from the smectic A phase via a spiralling S = + 2 disclination. Unlike a nematic which r…
Both forward angle and 90 degrees light-scattering measurements have been used for cell sizing with stream-in-air flow systems with very little theoretical base for the measurements. Mie theory calculations are compared with measurements on plastic microspheres. Detector response for homogeneous spheres is shown to be…
Thermotropic liquid crystals offer uniquely ordered media for intermolecular reactions such as polymerization. Unlike the recently investigated topochemical polymerizations where molecules are rigidly constrained on lattice points [l], the liquid crystalline state permits full two-dimensional (nematic and cholesteric)…
The anchoring energy of a nematic liquid crystal can be evaluated from measurements of the tilt angle at the boundary of its substrate. The equilibrium between surface and elastic energies determines the geometric structure of the distortion. For an obliquely evaporated SiO film, the energy value is about 10-3 erg/cm2.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDirect tungsten-183 nuclear magnetic resonance: a powerful new structural tool for heteropoly- and isopolytungstate chemistryRafael Acerete, Charles F. Hammer, and Louis C. W. BakerCite this: J. Am. Chem. Soc. 1979, 101, 1, 267–269Publication Date (Print):January 1, 1979Publ…
Current-voltage data for metal oxide varistors are presented in the temperature range 100–1300 °C and for current densities as high as 103 A/cm2. The current-voltage characteristic can be crudely represented at all temperatures by a breakdown line I=CVα where α≳30 (and is somewhat voltage dependent) and a temperature-…
It is proposed that the liquid phase metal-non metal transition in carbon takes place between an sp hybridized non-metallic liquid, with coordination number two, and a strongly correlated liquid metal in which directional bonding remains important though the hybridization and coordination number will probably change.…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCarbon-13 Nuclear Magnetic Resonance Analysis of Model Compounds of Saturated End Groups in PolypropyleneA. Zambelli, P. Locatelli, and G. BajoCite this: Macromolecules 1979, 12, 1, 154–156Publication Date (Print):January 1, 1979Publication History Published online1 May 2002…
Abstract Die neuen Verbindungen NaAsSe 2 , NaSbSe 2 , NaSbTe 2 und NaBiTe 2 wurden dargestellt und strukturell aufgeklärt. NaSbSe 2 , NaSbTe 2 und NaBiTe 2 kristallisieren in der NaCl‐Struktur mit folgenden Gitterkonstanten: NaSbSe 2 : a = 596,6(2) pm, NaSbTe 2 : a = 631,7(2) pm, NaBiTe 2 : a = 636,6(3) pm. NaAsSe 2 k…
The miscibility of homogeneous diblock copolymers of 1-4-polybutadiene and cis-1-4 polyisoprene with either or both of the corresponding linear homopolymers was found to depend upon the relative lengths of the block segments and upon the coordinates of the binary or ternary mixture on the appropriate triangular compos…
SUMMARY Previous work, at foreign laboratories, essentially based on electron microscopy of longitudinal sections, has suggested a radial morphology for the aromatic poly‐amide high modulus fibres; the present paper gives direct evidence of such a morphology, thanks to a special preparation technique which allows a gr…
Compositionally modulated single-crystal InSb/GaSb superlattice structures have been grown by multitarget sputtering in order to investigate the effects of film growth parameters on the defect structure, abruptness, and coherence of sputtered heterojunctions. The layer thicknesses studied ranged from 12 to 70 Å. The p…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMagnetic-exchange interactions in binuclear transition-metal complexes. 19. Imidazolate- and biimidazolate-bridged copper(II) complexes. Crystal structure of .mu.-biimidazolato-bis(1,1,4,7,7-pentamethyldiethylenetriamine)dicopper(II) tetraphenylborateMuin S. Haddad, Eileen N…