Materials Literature
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It is shown that two new classes of smectic liquid crystals - esters and salicelidenanilines - have ferroelectric properties. The new ferroelectric smectics have a hightened hydrolitical stability. Their electrical and heat properties are investigated, the correlation between a chemical composition and spontaneous pol…
Abstract A series of polyester polyurethanes with a range of polyester contents was prepared from an ethylene glycol/propylene glycol/adipic acid polyster, butane diol, and methylene bis (4‐phenyl isocyanate) (MBPI). They were thermally degraded under vacuum and the products of degradation were identified. The urethan…
Shear waves are excited in a latex sample. One detects the vibrations of the sample using light scattering phenomena (Kossel rings). The amplitude of vibrations of the latex sample, when recorded as a function of the frequency of excitation, presents a series of resonances. Analysis of the resonance peaks allows to de…
Abstract The kinetics of K adsorption from solution to exchangeable phases were investigated on the Ap, A2, B21t, and B22t horizons of Dothan soil (Plinthic Paleudult) from two locations in Virginia. These soils are loamy sands in the upper horizons with clay content increasing with depth, are slightly acidic in the s…
The ring closure (bleaching) reaction of photochromic indolinobenzospirans is a fast unimolecular process with a finite activation volume. When the reagent is immobilised in a rigid matrix, the isomerization is controlled by the amount of free volume in the neighbourhood of the reacting molecule and so the distributio…
The survival of plant cells may be tested rapidly and conveniently by staining tissue sections in a solution of Evan's blue (0·5% w/v) after exposure to solutions of high salt concentration or low osmotic potential. Living cells retain the ability to exclude Evan's blue at the plasma membrane and remain their natural…
The title crown ether forms three types of compound with lanthanide ions, [M(NO3)3(crown)](M = La—Nd), M4(NO3)12(crown)3(M = La—Gd), and [M(NO3)3(OH2)3]·crown (M =Gd—Lu). Crystal structures of the first and third types have been determined by X-ray diffraction. The complex [La(NO3)3(crown)] is orthorhombic, space grou…
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…