Thermodynamics and dynamics of polypeptide liquid crystals
Abstract
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Instability of certain shear flows in nematic liquids
We have studied the simple shear flow, in the laminar regime, of a nematic (uniaxial) liquid film between two glass plates with carefully imposed boundary conditions. In the case considered here, the optical axis at rest is normal both to the flow velocity and to the velocity gradient. Using various methods of optical…
A model for the structure of ionomers
Abstract The nature of the distribution of ionic groups in cesium salts of ethylene‐methacrylic acid and ethylene‐acrylic acid copolymers containing 2.1 to 6.3 mol% acid was examined using the small‐angle and wide‐angle x‐ray scattering techniques. The low‐angle data containing a maximum characteristic of these materi…
A molecular model for yield and flow in amorphous glassy polymers making use of a dislocation analogue
A model has been proposed to account for the yield behaviour of amorphous glassy polymers. The critical step in the yield process is envisaged as being the nucleation under stress of small disc-shaped sheared regions (the strain fields of which are analogous to those of dislocation loops) that form with the aid of the…
Critical elastic constants and viscosities above a nematic-smectic a transition of second order
2e ordre créent des singularités de certaines viscosités et constantes élastiques en phase nématique. Le comportement critique des constantes élastiques a déjà été calculé par P. G. de Gennes dans le régime hydrodynamique q03BE ~ 1. En partant des mêmes hypothèses et en utilisant comme outil de travail la théorie de l…
Theory of fluctuation superconductivity from electron-phonon interactions in pseudo-one-dimensional systems
The physics of quasi-one-dimensional solids which undergo a Peierls distortion, such as the organic material TTF-TCNQ (tetrathiofulvalinium-tetracyanoquinodimethan) is discussed. In particular, the effect of fluctuations into the Fr\"ohlich superconducting state on the free energy and the electrical conductivity is ex…
Biochemical significance of porphyrin .pi. cation radicals
ADVERTISEMENT RETURN TO ISSUEPREVArticleBiochemical significance of porphyrin .pi. cation radicalsDavid Dolphin and Ronald H. FeltonCite this: Acc. Chem. Res. 1974, 7, 1, 26–32Publication Date (Print):January 1, 1974Publication History Published online1 May 2002Published inissue 1 January 1974https://pubs.acs.org/doi/…
Effects of Irradiation and Oxygen on Hydrogen Environment Embrittlement of Selected Alloys
Testing in 10-MPa (1500-psi) hydrogen did not reduce the notched strength of irradiated Inconel 718 or A286; however, irradiated Ti-5Al-2.5Sn suffered reductions in notched strength of 6.9 percent. Likewise, irradiated CW 301 stainless steel lost 81 percent of the notched strength in 10-MPa (1500-psi) hydrogen. For hy…
Collision-broadened phonon line shape in the overdamped or hydrodynamic regime
It can be shown that if amplitude as well as momentum changes during phonon scattering events are taken into account, the line shape associated with infrared- or Raman-active lattice modes can be of the Lorentz or Van Vleck-Weisskopf form as well as of the damped-oscillator form. An expression is derived for the susce…
{1122} Slip System in Magnesium
The slip mode operative in the c-axis compression of magnesium was examined using precisely-oriented single crystals. From recorded stress-strain curves and observations with light and transmission electron microscopes, it was found that (1) the {1122} <1123> slip system operates at all temperatures investigated (from…
Defect-annealing in neutron-damaged β-Ga2O3
A study is made of the effect of fast neutrons on the electrical conductivity and thermoelectric power and also the neutron-induced defects in β-Ga2O3. It is found that the conductivity decreases while the thermoelectric power increases after an irradiation of about 1017 nvt. This is explained by assuming that the def…
Terpenoids. Part XXVIII. Total synthesis of enmein
The total synthesis of enmein (1) is reported. The diol acetal, ent-3β,20-epoxy-3-methoxy-17-norkaurane-6α,16α-diol (3) was used as the important relay compound.
Mise en Évidence D'Un Composé BiBo3 et de Son Polymorphisme par Spectroscopie Vibrationnelle
Abstract Bismuth orthoborate BiBO 3 , a non‐existent compound after the Bi 2 O‐B 2 O 3 phase diagram, has been obtained by melting a mixture of H 3 BO 3 and Bi 2 O 3 corresponding to the BiBO 3 composition and subsequent cooling. Two different phases are obtained, depending on the cooling conditions. Infrared and Rama…
Electroinitiated Polymerization of Tetrahydrofuran
Electroinitiated polymerization of tetrahydrofuran (THF) was accomplished in 1 M LiClO 4 ‐ THF organic electrolyte solutions by anodic electrolysis on platinum electrodes in a three‐compartment cell. THF was found to polymerize to form a viscose gel at 25°C. The rate of polymerization was followed by measuring the ele…
Coupling strength in the theory of radiationless transitions: f → f and d → f relaxation of rare-earth ions in YAIO3 and Y3AI5O12
The dependences of the radiationless relaxation rate constant on the effective mediating phonon energy, the equilibrium displacement of the adiabatic surfaces, the energy gap, and the temperature are numerically examined in terms of a generalized theoretical rate expression derived from quantum statistical theory. Spe…
Thermophysical Properties of Matter-The TPRC Data Series. Volume 10. Thermal Diffusivity
Abstract : The TPRC Data Series published in 13 volumes plus a Master Index volume constitutes a permanent and valuable contribution to science and technology. This 17,000 page Data Series should form a necessary acquisition to all scientific and technological libraries and laboratories. These volumes contain an enorm…
Corrosion of Pure and Amalgamated Zinc in Concentrated Alkali Hydroxide Solutions
Corrosion of pure and amalgamated zinc in pure concentrated solutions was investigated using two methods: ( a ) galvanostatic measurements of the kinetics of hydrogen evolution with electrodic assessment of corrosion properties of the system, and ( b ) volumetric measurement of the hydrogen evolution reflecting direct…
Analysis of the Grain Size Dependence of the Yield Stress in Copper-Aluminum and Copper-Nickel Alloys
Grain size dependence of the yield stress in polycrystalline copper-aluminum and copper-nickel alloys is measured at 77, 194 and 293°K. It is found that the Hall-Petch relation is valid for these materials. The Petch slope ky is nearly independent of the temperature, but increases with increasing solute concentration.…
Magnetic and Magnetoelastic Properties of Highly Magnetostrictive Rare Earth-Iron Laves Phase Compounds
The rare earth‐Fe2 (RFe2) compounds possess huge magnetic anisotropies and magnetostrictions at room temperature. This, coupled with a relatively high Curie temperature and magnetic saturation, makes these alloys attractive for various applications, including magnetostrictive transducers and permanent magnets. A varie…
Spinodal Decomposition in Alnico 8 Magnet Alloy
An electron microscope study is made on isothermal decomposition in Alnico 8 alloy as annealed around 800°C for 10–90 min in a magnetic field. The results obtained are found to agree well in many essential aspects with Cahn’s theoretical predictions on spinodal decomposition in a ferromagnetic cubic alloy. In the case…