Técnicas electroquímicas cuali y cuantitativas para medir los efectos de las adiciones sobre la corrosión de las armaduras
Not available
Materials Literature
文献浏览
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
Direct Evidence for Intrinsically Broken Chemical Ordering in Melt-Quenched Glasses
The chalcogen site in bulk glasses of Ge${\mathrm{Se}}_{2}$ and Ge${\mathrm{S}}_{2}$ has been probed via nuclear quadrupole interactions with use of $^{129}\mathrm{Te}^{m}$ impurity atoms as parent in $^{129}\mathrm{I}$ M\"ossbauer emission spectroscopy. Two distinct types of chalcogen sites are observed and are shown…
Structure and activity of phosphoglycerate mutase
The structure of yeast phosphoglycerate mutase determined by X-ray crystallographic and amino acid sequence studies has been interpreted in terms of the chemical, kinetic and mechanistic observations made on this enzyme. There are two histidine residues at the active site, with imidazole groups almost parallel to each…
Helium bubble behaviour in b. c. c. metals below 0.65 T m
Abstract We have considered the methods available for distinguishing between the rate-controlling mechanisms for gas bubble migration in metals at temperatures below 0.6Tm. We show that several combinations of mechanism, gas behaviour and rate-controlling process give rise to similar power laws describing the rate of…
The structure and properties of methane adsorbed on graphitized carbon black determined by neutron diffraction
Neutron diffraction patterns from methane-d4 on the graphitized carbon black, Vulcan III, have been measured over a range of coverage and temperature. At coverages up to 0·9 monolayers the methane forms a two dimensional layer in registry (√3 × √3) with the basal planes of graphite that make up the surface. At higher…
Control of Calcium Carbonate Nucleation and Crystal Growth by Soluble Matrx of Oyster Shell
A calcium-binding soluble protein extracted from oyster shell suppresses calcium carbonate nucleation and decreases the rate of crystal growth in vitro. These findings suggest that soluble matrix may regulate shell growth.
Mössbauer study of the low-temperature phase of magnetite
The Mössbauer spectrum of the low temperature phase of Fe3, O4, is studied at 4.2 and 78 K. The spectrum can be resolved in five sextets, one arising from the Fe3+ ions on the A-sites, two from the Fe3+ ions on B-sites, and two from Fe2+ ions on the B-sites. The data of quadrupole splitting and hyperfine fields are us…
Electronic behaviour of SnS2 crystals
Electronic band gaps of various polytypes of SnS2, are estimated from the measurements of the variation of conductivity with temperature. It is found that for hexagonal polytypes, the band gap decreases as the polytype periodicity increases, as for instance the band gap values for the basic polytype 2H and the long pe…
The far-infrared spectra of some mixed cobalt zinc and magnesium zinc ferrites
The far-infrared spectra of five mixed ferrites in the range 200 to 640 cm−1 are reported. Four bands are observed. The high frequency band (v1) and low frequency band (v2) are assigned to the tetrahedral and octahedral complexes, respectively. A small band (v3) around v2 is observed and its intensity increases with d…
An analytical model of SEM and STEM charge collection images of dislocations in thin semiconductor layers: I. Minority carrier generation, diffusion, and collection
A three-dimensional analysis is given of the generation, diffusion, and collection of minority carriers injected by an electron beam in a semiconductor containing a p–n junction parallel to the surface. Using a modified Gaussian approximation to the three-dimensional electron beam dissipation function, analytical expr…
Radiative recombination in crystallineAs2S3
Two photoluminescence bands characterized by their excitation energy are observed in orpiment ($c\ensuremath{-}{\mathrm{As}}_{2}{\mathrm{S}}_{3}$). We assign the emission band with the peak energy of 1.53 eV to defect-related bound-exciton recombination. The luminescence band at 1.25 eV is induced by band-to-band exci…
A simple interpretation of Raman excitation spectra of metalloporphyrins
A simple treatment of vibronic coupling in metalloporphyrins is described. Electronic degeneracy in the excited states is treated to arrive at simple expressions for the Raman excitation spectra and the absorption spectrum. The expressions are simple analogs of the usual A and B term expressions for the scattering ten…
An investigation of the 1H nmr isotropic shifts for some methyl-substituted bipyridine complexes with Ni(II) and Co(II)
In order to extend existing ideas on isotropic spin transfer mechanisms in bipyridine–metal complexes, a series of unsymmetrical methyl-substituted bipyridine ligands, and their nickel(II) and cobalt(II) complexes, have been prepared, and their 1 H nmr isotropic shifts measured experimentally. Simulating different ele…
The antiferromagnetic Mn2 molecule
ESR measurements are reported for Mn2 in kypton and xenon matrices at 4 °K.(AIP)
Manufacture of n-Butanol and 2-Ethylhexanol by the Rhodium Oxo Process and Applications of the Alcohols
The oxo process consists of the reaction between an olefin, carbon monoxide, and hydrogen, in the presence of a catalyst (rhodium or cobalt) to form an aldehyde with one more carbon atom than the starting olefin. R-CH=CH 2 + CO + H 2 Catalyst/ R-CH 2 -CH 2 CHO The only exception is with the cobalt catalyst when the st…
Correlation functions of amorphous multiphase systems
We give two general integral expressions for the first and second derivatives of the so-called stick probability functions which are commonly used in analyzing x-ray-scattering results. Then it is shown that by letting the length of the stick go to zero, the limit of the second derivative can be expressed in terms of…
Raman scattering cross section of adsorbed pyridine molecules on a smooth silver surface
We have determined the Raman scattering cross section of pyridine molecules adsorbed on a "smooth" surface of silver prepared and characterized in an ultrahigh-vacuum chamber. The Raman intensity of the 1004-${\mathrm{cm}}^{\ensuremath{-}1}$ line of adsorbed pyridine was calibrated against the scattering intensity of…
Semiclassical image potential at a solid surface
A surface dielectric function of a semi-infinite plane-bounded metal is defined in the spirit of the plasmon-pole dielectric function of the bulk. It is modeled in such a way that the surface-plasmon dispersion relation is recovered for small momentum transfer. This function is employed to compute the image potential…
Investigation of the vibronic properties ofCu3VS4,Cu3NbS4, andCu3TaS4compounds
Infrared-reflectivity results on ${\mathrm{Cu}}_{3}$V${\mathrm{S}}_{4}$ and Raman scattering data as a function of temperature and hydrostatic pressure for ${\mathrm{Cu}}_{3}M{\mathrm{S}}_{4}$ (with $M=\mathrm{V},\phantom{\rule{0ex}{0ex}}\mathrm{N}\mathrm{b},\phantom{\rule{0ex}{0ex}}\mathrm{T}\mathrm{a}$) are reported…
Band structure and localization in incommensurate lattice potentials
A metal-insulator transition was found by Aubry in a one-dimensional tight-binding model containing a modulation potential incommensurate with the crystal lattice. In this article the extended bandlike states that occur in the metallic regime are studied using a quasiclassical approach. Near the metal-insulator transi…