Materials Literature
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The isotypic crystal form for the smectogenic p-n-alkoxybenzoic acids has been determined by room-temperature single-crystal x-ray diffraction analyses for the acids having 7, 8, 9, and 10 carbon atoms in the alkyl chain. The molecules are present in the crystals as centrosymmetric hydrogen-bonded dimers. The alkyl ch…
Photoluminescence spectra from three species of n-GaAs, lightly Si doped, heavily Si doped, and lightly Te doped, show the onset of additional radiative transitions upon modest annealing in the 550–700 °C range. Etch-back procedures reveal that the new structure is all surface related. It is attributed to the creation…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCarbon-13 and Proton Nuclear Magnetic Resonance Studies of Cellulose NitratesTing Kai WuCite this: Macromolecules 1980, 13, 1, 74–79Publication Date (Print):January 1, 1980Publication History Published online1 May 2002Published inissue 1 January 1980https://pubs.acs.org/doi/…
Enzyme I of the phosphoenolpyruvate - sugar phosphotransferase system (PTS) has been purified to homogeneity from Escherichia coli. A merodiploid strain P650 which had an extra copy of the gene for enzyme I resulting in a twofold increase in the amount of activity was used. The enzyme is a dimer of 67 000 +/- 5000 mol…
Consideration of the influence of crystal symmetry, macrosymmetry, and inter-phase connectivity have been used to explore possible macrostructures of interest as piezoelectric or pyroelectric composites. Based on these design considerations, ceramic-plastic composites have been fabricated with 3–3 phase connectivity b…
By addition of 5–10% Bi2Ti2O7 to powders with composition in the vicinity of BaNd2Ti5O14, temperature coefficient of permittivity of sintered ceramics may be decreased from approximately −100 ppm/°K to −25 ppm/°K. Dense, fine grained ceramics were prepared with permittivity within the range of 70–90 and tan δ below 3…
Detailed optical absorption data are reported for the divalent europium ion in NaCl, KCl, RbCl, KBr, RbBr, and KI single crystals at 300 and 77 K. Values of the oscillator strength are calculated for all the observed bands in the optical spectra at both temperatures. It is established that the optical spectra are well…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMicrophase Separation in Low Molecular Weight Styrene-Isoprene Diblock Copolymers Studied by DSC and 13C NMRB. Morèse-Séguéla, M. St-Jacques, J. M. Renaud, and J. Prod'hommeCite this: Macromolecules 1980, 13, 1, 100–106Publication Date (Print):January 1, 1980Publication Hist…
A poly (dA, [2-14C]dT) copolymer has been synthesized using terminal deoxynucleotidyltransferase. Treatment of the polydeoxyribonucleotide with potassium permanganate converts the thymine residues to urea and N-substituted urea derivatives, while the adenine residues are resistant to oxidation. This damaged polymer ha…
Thermal expansion of β-Mg2SiO4 (modified spinel; orthorhombic symmetry) was measured by the X-ray powder diffraction method in the temperature range between 20°C and 800°C. Grüneisen's theory of thermal expansion was applied to the linear and volume expansion data, and thermal expansion coefficients were obtained to b…
The dilute solution dynamics of spheroid–cylindrical molecules, i.e., straight cylinders with oblate, spherical, or prolate hemispheroid caps at the ends, is studied in detail. The translational and rotatory diffusion coefficients and the dynamic intrinsic viscosity are evaluated numerically for short cylinders by det…
One of the major causes of failure of conventional stainless steels in sea water and other chloride containing environments is attack by crevice corrosion with the result that several special grades with improved resistance have been developed. A new technique has been developed using a mathematical model combined wit…
A significant effort has been devoted during the last 10 years to develop a route to thermally stable polymers without the evolution of volatile by-products. Most high-temperature polymers are prepared by condensation polymerization which involves the elimination of volatiles. These volatiles are responsible for sever…
Abstract Four solvents of cellulose have been studied by using 13 C‐NMR spectroscopy. All these solvents, N ‐methyl morpholine‐ N ‐oxide, methylamine, hydrazine, and paraformaldehyde (PF), contained dimethyl sulfoxide (DMSO) as a cosolvent. Oligomers of cellulose of DP = 10 soluble in hot DMSO have been used as model…
ADVERTISEMENT RETURN TO ISSUEPREVArticleOrbital reversal in (oxalato)copper(II) linear chainsJ. J. Girerd, O. Kahn, and M. VerdaguerCite this: Inorg. Chem. 1980, 19, 1, 274–276Publication Date (Print):January 1, 1980Publication History Published online1 May 2002Published inissue 1 January 1980https://pubs.acs.org/doi/…
Abstract The initial stage of the suspension polymerization of poly(vinyl chloride) (PVC) is characterized by the formation of colloidally stable micron‐sized grains of PVC inside the polymerizing ca. 150 μm vinyl chloride droplets. The fate of these micron‐sized PVC grains depends upon the agitation conditions. If no…
Abstract High pressure CO 2 sorption data in polycarbonate (PC) are reported as a function of temperature and thermal history. The bulk physical structural changes produced by annealing at 125 and 135°C were monitored by density and thermal property changes. The sorption data are analyzed by the dual sorption model wh…
The quantitative determination and depth profiling of fluorine in the surface region of various substrates using nuclear reaction microanalysis was studied. Differential cross sections and excitation functions for the reaction 19 F(p, α 0 ) 16 O and 19 F(p, α γ) 16 O were investigated in great detail, especially in th…
R. G. Godden and D. R. Thomerson, Analyst, 1980, 105, 1137 DOI: 10.1039/AN9800501137
Abstract The isothermal crystallization of isotactic polypropylene at different temperatures in the presence of fibrous substrates has been investigated. It is shown that preferential transcrystalline growth occurs at the fiber surface and that changes in nucleation density in the bulk material adjacent to the fibers…