Materials Literature
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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOxygen-17 nuclear magnetic resonance spectroscopy of polyoxometalates. 1. Sensitivity and resolutionM. Filowitz, R. K. C. Ho, W. G. Klemperer, and W. ShumCite this: Inorg. Chem. 1979, 18, 1, 93–103Publication Date (Print):January 1, 1979Publication History Published online1…
When a smectic-$A$ phase is composed of chiral molecules, it exhibits an electroclinic effect, i.e., a direct coupling of molecular tilt to applied field. The pretransitional behavior of the electroclinic effect in the $A$ phase is used to study the critical behavior near the second-order, smectic-$A$---smectic-$C$ ph…
Tabulations are presented of relativistic Hartree-Fock atomic form factors F (x,Z), for values of x (=sin(ϑ/2)/λ from 0.01 to 109 Å−1, for all elements Z=1 to 100. For Z=1, F (x,Z) is given by the exact expression of Pirenne. For Z=2 to 98, x=0.01 to 2.0 Å−1, the tabulated values are those of Cromer and Waber given in…
"Corrosion Engineering." British Corrosion Journal, 14(1), p. 4
We develop a new theory of the spin-Peierls transition in spin-\textonehalf{} Heisenberg chains, treating the phonons in a mean-field random-phase approximation (RPA) as in previous work, but calculating the relevant response functions of the spin system using the procedure of Luther and Peschel. We show that the RPA…
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For staining myelin with silver a physical development technique has been devised that can render visible the thinnest fibers in various animal species, including fishes and reptiles, even in the early phase of myelination and may be applied to both frozen and embedded materials. Its principle is as follows: Myelin ca…
The electrochemical polymerization of pyrrole on platinum produces a strongly adhered, durable film with enhanced conductivity and good electrode properties.
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Intense Raman scattering by pyridine molecules adsorbed on silver or gold aqueous sol particles of dimensions comparable to the wavelength is reported. The degree of intensity enhancement is strongly dependent on the excitation wavelength, with a sharp resonance Raman maximum for excitation at the wavelength of the Mi…
The paper describes the testing and design of tapered-steel cantilevers used as energy dissipating devices, manufactured from either round bar or plate, which can be used in isolation systems to protect buildings or bridge decks against earthquake attack. The steel cantilever energy absorber is a simple device which c…
It is well known that the photovoltage in semiconductors, whatever its nature, cannot exceed the energy gap, which is several volts. For instance, in a homogeneous semiconductor the Dember (diffusion) photovoltage does not exceed the following value [3.6] for an infinitely large intensity of the exciting light: $$ V =…
The g eff =30/7 isotropic signal in the EPR of high-spin Fe 3+ compounds is discussed for both tetragonal rhombic crystal fields by reference to the resonance in calcium tungstate. The Fe 3+ /CaWO 4 EPR signals are shown to arise from Fe 3+ in two slightly different interstitial sites in the crystal; the crystal field…
The electronic response including electron-phonon matrix elements in a simple tight-binding model is calculated for the 'd z2 ' sub-band in 2H-NbSe 2 . This function, in contrast to the bare response, shows a peak in the region of the charge density wave (CDW) wavevector. It is therefore concluded that the CDW is driv…
Barium borate glasses containing 0-35 mole% V 2 O 5 were found to be homogeneous. Optical absorption spectra indicated that only V 4+ of the lower valence states of vanadium was present. The molar volume data suggested that a change in the structure associated with vanadium ions occurred at around 22% V 2 O 5 . ESR sp…
We have studied the lattice dynamics of bcc Zr at 1400 K. We find that (a) the [111] longitudinal branch plunges rapidly to low frequencies in the vicinity of $q=\frac{2}{3}[111]$ indicating a nautral inclination for this metal to undergo a structural transformation to the $\ensuremath{\omega}$ phase, (b) the [110] lo…
The surface vibrational modes of atomic hydrogen adsorbed on W (100), observed by electron-energy-loss spectroscopy in off-specular directions, indicate bridge bonding at all coverages. The vibrational frequencies show a dependence on the W-H-W bond angle which changes due to reconstruction of the tungsten lattice. Th…
Abstract Data on the distribution of collagen fibril diameters in various connective tissues have been collected and analysed for common features. The diameter distributions of the collagen fibrils at birth and in the foetal stages of development are unimodal, whereas at maturity the mass-average diameter of the colla…
Refinement of the crystal structure is made for the room temperature phases of LaNbO4 and NdNbO4. The final R index is 0.0457 for LaNbO4 and 0.0342 for NdNbO4. From precise atomic parameters, the vectors of the shuffles for all atoms out of “the plane of shear” (010) are determined. Since the twins in the crystals are…
Stress-strain characteristics in silicon crystals are investigated as a function of the temperature, the strain rate, and the initial density of dislocations. Dislocation multiplication in the yield region is also observed by means of etch-pit technique. Specimens with lower initial densities of dislocations have high…