Materials Literature
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The infrared spectra of the fourteen complex ions [LnT4]- (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb, Lu; T = tropolonate anion) have been determined. One band within the range 480 to 510 cm-1 is found to be significantly metal-sensitive and is accordingly assigned to the metal-oxygen stretching frequenc…
The paper considers the properties of vector analogs of the Sobolev spaces, , which appear in the study of various models of continuous media. Korn's inequality, proved in the paper, makes it possible to reduce the problem of compactness of the imbedding operators in these spaces to the scalar case and, consequently,…
Abstract Photoelectron spectra in the region 6 to 21 eV have been measured for carbonyl halides (fluoride, chloride and bromide) and carbonyl cyanide. In a number of cases, vibrational structure coupled with the ionization process has been resolved and correlated with the known frequencies of the parent molecule. Ioni…
Abstract Pour polymériser l'ε‐caprolactone, on a opéré en solution dans le benzène, le toluène ou le tétrahydrofuranne, sous atmosphère inerte, à 55°C, avec le méthanolate ou l'éthanolate de sodium comme amorceur de polymérisation. Les échantillons ont été fractionnés à 34°C par addition d'isooctane à leur solution da…
Abstract The numbers of rings formed in the reactions of hexamethylene diisocyanate with two polyethylene glycols have been determined as a function of dilution and ratios of reactants. In this work the cryoscopic apparatus developed in the preceding paper has been utilised. It is found that more rings are formed (a)…
Abstract It has been known for several years that pregnenolone is the biogenetic precursor of hormones of the adrenal cortex and of progesterone in the animal kingdom. The route to the androgenous and oestrogenous hormones also goes via this intermediate. However, in the plant kingdom it was only later that the role o…
The effect of the mechanical constraints exerted by coatings upon electromigration in thin films is evaluated on the basis of known pressure effects upon diffusion.
A flood-gun arrangement is shown to be useful in alleviating the sample-charging problem in x-ray photoelectron spectroscopy. Modest currents (<10−8 A) of low-energy electrons result in the shifting of photoelectron energy peaks to the proper positions and the reduction of the peak widths.
Measurements of the temperature dependence of the dielectric constants ε‖, ε⊥, and εis of some nematic liquid crystals with strong positive dielectric anisotropy (ε‖ ≃ 3 ε ⊥) are reported. The low frequency dispersion regions of the dielectric constants parallel to the unique axes were measured to be in the range from…
It is shown that piezoelectric effects can be easily derived from bulk properties and are expressible in terms of linear and quadrupole moments of variations in charge density induced by atomic displacements. The linear-moment contribution is determined by optic macroscopic effective charges and internal-strain parame…
A study of the quantum efficiency of the luminescence of gadolinium and terbium in borate glasses and of the energy transfer between these ions is presented. From our measurements of fluorescence decay times, absorption, fluorescence, and excitation spectra, we calculated the fluorescence quantum yield of the 6P7/2 ga…
The electric-dipole intensities of Er 3+ spectra in six different host lattices have been calculated on the basis of Judd-Ofelt theory, which takes into account the effect of a mixing of higher configurations of opposite parity into the f n configuration through odd parity spherical harmonics in the ligand field inter…
Micro-Heterogeneity in the Biosynthesis of CollagenDetailed analyses of the structure of the polypeptide chains of collagen has revealed a "micro-heterogeneity" of the amino acid sequences. Sequencing of the first 50 amino acid residues from the NH2-terminal end of the α1 chain of rat skin and tendon collagen indicate…
The trapping of positrons at vacancy sites in some metals provides a new and sensitive method for the equilibrium determination of vacancy-formation energies. Data are presented for Al, Cd, In, Pb, and Zn and fitted to a model allowing presentation in the form of Arrhenius plots. The vacancy concentration is not deter…
The origin of electronic states in two classes of semiconductors is explored: (i) semiconductors containing group-VI elements in twofold coordination, and (ii) tetrahedral semiconductors. In the first case the valence band arises from the unshared electron pair (lone pair) of the group-VI atom. We examine the effects…
Crystals of armalcolite, Mg(0.5)Fe(0.5)Ti(2)O(5), up to several millimeters in length have been grown from a glass initially having the composition of lunar rock 10017. A single-crystal x-ray study has confirmed that the crystals are isomorphous with pseudobrookite and has shown that the cations are strongly ordered,…
Intracellular Biosynthesis of CollagenWork from several laboratories has demonstrated that the biosynthesis of collagen occurs by a series of sequential steps: assembly on ribosomal complexes of a polypeptide precursor of collagen that we have called "protocollagen"; hydroxylation of appropriate Pro and Lys residues i…
The carbothermic reduction in vacuum of thorium oxide with graphite has been studied with the aid of a high temperature thermobalance at temperatures range of 1,300°–1,900°C. The effects of differences in the reaction temperature, molecular ratio of the reactants, and in the state of the reactants such as differences…
Experimental findings of an irradiation enhancement of precipitation in stainless steel under observation in the High Voltage Electron Microscope (HVEM) are presented. The results for the case of electron irradiation are compared with previous studies of precipitation under neutron irradiation in thermal and fast reac…
SUMMARY Among the examples reviewed are volume‐fraction measurements in phase diagram and kinetic studies, properties dependent upon internal surface area, the characterization of phase arrangements by contiguity, proximity and dihedral‐angle measurements. The use of grain boundary and particle spacings in studies of…