Materials Literature
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Abstract The type of stress pulse produced when a liquid mass strikes a solid at high velocity is first examined. Compressible behaviour, giving rise to a sharp peak of pressure, is found to occur in the initial stages of the impact. The duration of this peak depends on the dimensions and impact velocity of the liquid…
Moths, by virtue of the loose scales that cover their wings and bodies, are admirably adapted to elude capture by orb-weaving spiders. Rather than sticking to the web, they may simply lose some of their scales to the viscid threads, and then fly on. Other insects, covered with detachable hairs or waxy powder, are simi…
The theory developed by Ziman for the scattering of phonons by electrons is extended to high temperatures using the formalism of Klemens and Callaway. The theory is applied to the experimental results recently published by Dismukes et al. on the effect of doping on the thermal conductivity of Ge-Si alloys. After subtr…
Experimental photoemission data from copper and silver are presented and interpreted in detail in terms of the calculated band structures over a photon energy range from 1.5 to 11.5 eV. It is shown that nondirect optical transitions are stronger than direct ones in both metals. In fact, the only direct optical transit…
The electron paramagnetic resonance of Re4+ in single cubic crystals of K2PtCl6 at wavelengths of 3 cm, 1 cm, and 8 mm is reported. The experimental results were analyzed assuming the Re4+ ground state is a spin quartet with S=32 and I=52. The cubic spin Hamiltonian is given by H=gβH·S+AI·S+uβ{HxSx3+HySy3+HzSz3−15(H·S…
Absorption, fluorescence, and excitation spectra of aqueous solutions of europium(III) perchlorate, chloride, nitrate, ethylenediaminetetra-acetate, and diethylenetriaminepenta-acetate were investigated. The latter three anions readily form complexes and were examined over a range of concentrations. The organic anions…
The interpretation of the energies of excimer luminescence of some polyacenes is considered and it is shown that neither simple molecular exciton attitudes nor charge resonance attitudes can provide satisfactory agreement with experiment. The D2k excimer formed from D2h aromatics is investigated and it is shown that t…
The problem of surface diffusion-controlled whisker growth is considered in a moving frame of reference. In addition, diffusive exchange with the substrate, a problem not treated heretofore, is considered. The results are compared with experiment and with prior treatments of whisker growth. The possibility of occurren…
The absorption and fluorescence spectra of Eu3+ in single crystals of Y2O3 have been observed and analyzed. The intermediate-coupling free-ion energy levels for Eu3+, including the effects of the 46 singlet states of the 4f6 configuration, are presented for all levels appearing below 41 000 cm—1. The results obtained…
I have touched upon the great variety of crystal forms and dendritic forms in nature, have discussed the essential physics involved in the generation of these forms during either constrained or unconstrained crystal growth, and have shown how this knowledge helps in the classification of this seemingly infinite variet…
Abstract : Evidence is presented that the atomic arrangement of high-pressure FeVO4 is similar to that of ambientpressure FeNbO4. Evidence is presented in the form of comparing the indexing of high-pressure FeVO4 and the disordered wolframite FeNbO4, which indicates that FeVO4 crystallizes in the disordered wolframite…
In contrast to the extensive studies performed on AgBr and AgC1 l i t t le effort has been made to unders tand the nature of s t ructural disorder in AgI, CuC], CuBr and CuI. This is p r imar i ly a consequence of the comparat ive s t ructural s impl ic i ty of AgC1 and AgBr, as Table 1 i l lustrates. In t r ins ic th…
The structure of a synthetic iron mica, KFe~+(Fea+Sia)O10(OH)~, determined from visually estimated intensities, shows very slight departure from Pabst's idealized biotite structure. The sextuple cell formerly used to describe micas accounts for the observed twinning.
The lactic dehydrogenase of a strain of Streptococcus bovis specifically requires fructose-1,6-diphosphate for activity. Phosphate or fructose-1-6-diphosphate prevents inactivation of the dehydrogenase, but phosphate and other compounds cannot be substituted for the fructose-1,6-diphosphate required for activity. Lact…
Abstract The shear mechanical impedance of six polydimethylsiloxane liquids of viscosity grades ranging from 100 to 100000 cS has been measured over the frequency range 10 kc/s to 78 Mc/s, and at temperatures from –50 to +50 °C. It was found possible to reduce the experimental data for each liquid to give a single cur…
The diffusion of radioactive Cr, Mn, Fe, Co, Ni, Cu, and Nb tracers in bcc gamma uranium has been measured from 780 to 1080\ifmmode^\circ\else\textdegree\fi{}C, using the thin-layer sectioning technique. The Arrhenius plots are curved at low temperatures; the curvature is not due to diffusion along grain boundaries or…
The magnetic structure of Co${\mathrm{Cl}}_{2}$\ifmmode\cdot\else\textperiodcentered\fi{}2${\mathrm{H}}_{2}$O has been investigated by means of single-crystal magnetic susceptibility and proton nuclear magnetic resonance (NMR) measurements. A transition to a two-sublattice antiferromagnetic structure with large uniaxi…
A new electron-phonon interaction characteristic of layer structures is described. Depending on the strength of the coupling between electron and lattice, this interaction, which involves short-range forces, leads to free or self-trapped charge carriers. The theoretical findings are compared with the experimentally de…
The evidence for, and the factors determining, the formation of metal-to-metal (m-m) bonds in transition metal oxides, sulphides, halides, and related complexes are discussed. It is proposed that when metals of high preferred valence state are constrained to low formal oxidation states, m-m bonds will form to allow th…
Magnesium oxysulfate, 3Mg (OH h MgSO., 81-120, was preci pi tated from metastable aqueous solutions of MgO in M gSO.. The co mpound form s in solutions containing 12 percent or more of JVIgSO., .and ,remains unchanged in solutions containing 10 percen t MgSO., but at lower concentratIons IS converted to Mg(OHh. Magnes…