Materials Literature
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ABSTRACTS Brass alloys from Ife are compared with a selection of brasses from Benin. Four sources of mixed zinc and lead ore were used in Ife. In Benin lead and copper from different sources were added to these four alloys, which may represent the melting down of older castings. Comparisons are made with analyses from…
Abstract Dynamic mechanical and dielectric properties of amorphous regenerated films of silk fibroin were studied as a function of temperature. A mechanical loss tangent peak at about 175°C may be due to the segmental motion of the main chains in the amorphous silk fibroin film. The dynamic modulus of the amorphous si…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStudies of chloranil-donor adducts by x-ray photoelectron spectroscopy (ESCA)Kung T. Ng and David M. HerculesCite this: J. Am. Chem. Soc. 1975, 97, 15, 4168–4171Publication Date (Print):July 1, 1975Publication History Published online1 May 2002Published inissue 1 July 1975ht…
Abstract In the design of thermal degradation processes for polymers, the energy to degrade or volatilize the materials soften must be known. The heats of volatilization for six polymers were measured by differential scanning calorimetry (DSC), where the area under the degradation endotherm peak was shown to be direct…
The influence of the different phases of the discharge on the statistics of the breakdown processes has been investigated in a wide range of gap lengths (from 2 to 10 m) and applied voltage levels. The effect of the field distribution, along the gap and of the overvoltage ratio upon the development of each discharge p…
A subcellular fraction enriched in twisted tubules was obtained by differential centrifugation of a homogenate of neurons isolated from areas of the brain with many neurofibrillary tangles from patients with Alzheimer's presenile-senile dementia. A unique protein (molecular weight 50,000 daltons) which does not co-mig…
Phase relations in the systems alkali monotungstate‐tungsten trioxide were investigated in the range 600° to 1100°C.In the Li system, compounds with an A 2 O/WO 3 ratio of 1:2 and 1:4 are stable and melt incongruently at 745° and 805°C, respectively. In the Na system, the 1:2 compound melts congruently at 746°C, where…
The visible absorption spectrum and magnetic circular dichroism (MCD) spectrum have been measured for Cs2NaEuCl6 at room temperature. The absorption spectrum and Zeeman splitting have been measured at liquid helium temperature as well. The Eu3+ is in a site of six-coordinate octahedral symmetry. Transitions from the 7…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTGraft Copolymerization of 2-Methyl-2-oxazoline onto Chloromethylated Polystyrene and Hydrolysis of Graft Copolymer to a Chelating Resin of Poly(styrene-g-ethylenimine)Takeo Saegusa, Shiro Kobayashi, and Akira YamadaCite this: Macromolecules 1975, 8, 4, 390–396Publication Dat…
"The Theory of Polarization Phenomena." Optica Acta: International Journal of Optics, 22(7), p. 638
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTUnusual metalloporphyrins. XXIII. Unusual metalloporphyrin complexes of rhenium and technetiumM. Tsutsui, C. P. Hrung, D. Ostfeld, T. S. Srivastava, D. L. Cullen, and E. F. Meyer Jr.Cite this: J. Am. Chem. Soc. 1975, 97, 14, 3952–3965Publication Date (Print):July 1, 1975Publ…
Abstract Investigation of the clay mineralogy of forty-seven samples of sediments from boreholes in the western Nile Delta, an area little studied hitherto, and from surface sites on the mouth of the Nile and adjacent coast shows that the clay fractions consist of dominant iron-rich, dioctahedral, randomly interstrati…
The equilibrium shape of dissociated dislocations in thin foils of Cu-10 at.% Al is investigated by weak-beam electron microscopy. It is found that dislocations assume a truncated triangular shape caused principally by the reduction in line energy when Shockley partials rotate towards screw character. The effects of i…
An isolated acceptor impurity is shown to be responsible for the ∼113-meV deep luminescence band which is frequently seen in GaAs layers grown by molecular-beam epitaxy. We establish that this center, which is also observed in melt-grown and solution-grown GaAs and which has often been associated with the presence of…
Several electrochemical systems exhibit an intense color change when an electrochemical reaction is induced by an applied electrical field or current. The electrochemical and electro‐optical properties of several such systems have been investigated. These systems are termed electrochemichromic and they can be classifi…
Abstract The melting behavior of restrained isotactic polypropylene fibers is examined quantitatively in terms of the influence the anisotropic structural state of the polymer has on the observed properties. Two endotherm peaks are observed to occur in some of the samples. The formation and location of the multiple pe…
The effects of fabrication variables on the high‐temperature strength of hot‐pressed Si 3 N 4 containing 5 wt% Y 2 O 3 were studied. Materials containing a crystalline grain‐boundary phase, formed as a consequence of a high‐temperature presintering heat treatment and identified as Si 3 N 4 ·Y 2 O 3 , had high‐temperat…
Abstract The multiple melting transitions previously reported for cis ‐polyisoprene have been related to different morphological species observed in thin films using transmission electron microscopy. Two distinct types of spherulitic lamellar crystal have been identified which have characteristic growth rates, lamella…
In this paper a general spectral approximation theory is developed for compact operators on a Banach space. Results are obtained on the approximation of eigenvalues and generalized eigenvectors. These results are applied in a variety of situations.
The quantum efficiency of Dy 3+ ‐activated phosphors is reasonably high in lattices where a low activator concentration (≤ 1%) is already sufficient for effective energy transfer from the lattice to the activator ions. When more activator is needed for effective energy transfer, the quantum efficiency is limited due t…