Materials Literature
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Crystals of the title compound are monoclinic, space group C2/c, a= 18·14(1), b= 18·62(1), c= 18·51 (1)Å, β= 95·9(5)°, Z= 4. The heavy atoms were located by direct methods and the oxygen and sodium atoms by difference Fourier analyses, with block-diagonal least-squares refinement to R 0·083 for 2781 independent reflec…
SummaryTin coatings and some tin alloy coatings from various plating baths and on several substrates have been kept under observation for spontaneous whisker growth for periods up to 20 years. A review of the results and of information obtained elsewhere suggests that, although assured immunity from whiskers may be di…
The partial pressures of the gaseous species in equilibrium with solid silicon in the Si‐H‐Cl system are presented as a function of temperature for different Cl/H ratios and total pressures. Computations were performed using our recently determined value of Δ Hf ° 298 ( SiHCl 3 , g ) = − 116.9 kcal / mol . Experimenta…
The steady-state distribution of mobile point defects in a monatomic solid under irradiation has been calculated for a semi-infinite solid and for a foil. The calculation was performed for defect annihilation by mutual recombination, at internal sinks, and by diffusion to the surface. Simple approximations, accurate t…
Conditions for the nucleation of recrystallized grains are briefly reviewed with emphasis placed on the orientation-dependent aspects. Distinction is drawn between nucleation sites within grains, at grain boundaries, and at transition bands. These sites are shown to have different orientation dependences. The role of…
The inherent characteristics of the instrumented impact test are discussed. The hammer energy is reduced by deforming the test specimen, accelerating the specimen from rest, Brinell-type deformation at the load points, vibrations of the hammer assembly, and elastic deformation within the machine. The limitations of th…
Electron micrographs of calf-skin collagen in the reconstituted native-type fibril and the segmented long spacing (SLS) forms are matched with one another and with the distribution of charged residues in the known α1 chain sequence.It is shown that:a) the pattern of bands in SLS corresponds closely with the charge dis…
The lipids and fatty acids of two freshwater diatoms Nitzschia palea Kutz, Navicula muralis Lewin, and one marine species, Navicula incerta Grun. have been studied. The major lipid components in all species were triglycerides, monogalactosyl, digalactosyl and sulphoquinovosyl diglycerides, phosphatidyl glycerol, phosp…
Matrix reactions of H and D atoms from a microwave discharge source with oxygen molecules diluted in argon have produced significantly higher yields of HO2 and DO2 than the previous photolysis methods. Oxygen isotopic enrichment confirmed the previous vibrational assignments to HO2; significantly greater concentration…
Abstract
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…
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 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…
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…
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…
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/…
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…
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…
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…
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…