Materials Literature
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Poly(vinylidene fluoride) (PVDF) transducers are well suited for use in high frequency pulse-echo ultrasound systems because of their high bandwidth. We analyze the design parameters of PVDF transducers operating in the 100 MHz range using the KLM transducer model. The effect of backing layers, electrode configuration…
The shear stress resistance of cultured human endothelium was investigated on 6 mm polytetrafluoroethylene vascular grafts. Endothelial cell attachment was promoted by precoating the grafts with fibrin glue, which contained human fibronectin and inhibitors of fibrinolysis (aprotinin and tranexam acid). To evaluate the…
Abstract A systematic study of the effect of surface pretreatment of cellulosic fibers and the processing time and temperature on the mechanical properties of the cellulose‐containing polypropylene was undertaken. Using non‐treated fibers, the elastic modulus increased gradually with the cellulose content, typically d…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTBis(ethylenedioxy)tetrathiafulvalene: the first oxygen substituted tetrathiafulvaleneT. Suzuki, H. Yamochi, G. Srdanov, K. Hinkelmann, and F. WudlCite this: J. Am. Chem. Soc. 1989, 111, 8, 3108–3109Publication Date (Print):April 1, 1989Publication History Published online1 M…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT2,3,7,8,12,13,17,18-Octakis(.beta.-hydroxyethyl)porphyrin (octaethanolporphyrin) and its liquid crystalline derivatives: synthesis and characterizationBrian A. Gregg, Marye Anne Fox, and Allen J. BardCite this: J. Am. Chem. Soc. 1989, 111, 8, 3024–3029Publication Date (Print…
CdS and PbS clusters with sizes ranging from a few angstroms to 150 Å can be synthesized in polymers. The dependence of the band gap on the cluster size deviates from the prediction of a simple particle-in-a-box model owing to the breakdown of the effective-mass approximation. Instead, the dependence can be described…
Abstract The structure of synthetic nitro-5,10,15,20-tetraphenylporphyrinato(piperidine)cobalt(III) has been determined by X-ray diffraction method. The results revealed that the porphyrin plane is markedly distorted to nonplanar due to the steric interaction between the axial piperidine and the porphyrin core.
The effects of vanadium and other elements on the pitting resistance of an 18% chromium ferritic stainless steel (SS) with less than 168 ppm carbon and nitrogen are reported. Vanadium was added to the base alloy in the concentration range of 1 to 4%, alone and in combination with titanium, niobium, nickel, copper, sil…
Abstract An earlier thermo‐analytical study of black powder, using small sample masses and slow heating rates, has been extended to an examination of the behaviour of black powder under the less‐controlled conditions of ignition and combustion, by simultaneous measurement of temperature profiles and burning rates. Bur…
Abstract A group‐theoretical method within the framework of the Landau theory of phase transitions is proposed to obtain and analyse a complete set of critical (primary) and noncritical (secondary) order parameters condensing as a result of a phase transition (complete condensate). The principal problems that can be s…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe synthesis and structural characterization of the first gallacarborane sandwichMarc A. Bandman, Carolyn B. Knobler, and M. Frederick HawthorneCite this: Inorg. Chem. 1989, 28, 7, 1204–1206Publication Date (Print):April 1, 1989Publication History Published online1 May 2002…
Service loading imposed on engineering structures is often arbitrary or nonproportional. The paper presents an investigation of examining the effects of proportional and nonproportional loadings on the fracture behavior of mixed mode fracture. The anisotropic model of continuum damage mechanics capable of taking into…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChloride-induced assembly of manganese(II) complexes having oligomeric and chain structuresB. C. Unni Nair, J. E. Sheats, R. Ponteciello, D. Van Engen, V. Petrouleas, and G. C. DismukesCite this: Inorg. Chem. 1989, 28, 8, 1582–1587Publication Date (Print):April 1, 1989Public…
The Ba-hexagonal ferrites (BaFe 12 O 19 ) with Bi 2 O 3 as a sintering aid have been studied. The beneficial effects on magnetic and electrical properties are obtained for a ∼2.5 mol% Bi 2 O 3 content. The Bi 3+ ions in the present system seem to substitute for Fe 3+ at octahedral sites leading to formation of BaFe 12…
A vacancy relaxation model which predicts the DC lifetime, pulse DC lifetime, and AC lifetime for all waveforms and all frequencies above 10 kHz is proposed. The AC lifetimes of aluminum interconnect are experimentally found to be more than 10/sup 3/ times larger than DC lifetime at the same current density. AC stress…
The biotransformation of swertiamarin [1, a seco-iridoid glucoside isolated from Swertia japonica (Schult.) Makino] by human intestinal bacteria was investigated. Three metabolites were isolated and identified as erythrocentaurin (2), 5-hydroxymethylisochroman-1-one (3), and gentianine (4) by spectroscopic methods. Th…
Abstract The pressure‐volume‐temperature properties of poly(ether ether ketone) (PEEK) were studied experimentally at temperatures of 400°C and pressures to 200 MPa. Specific volume data were fitted successfully to the empirical Tait equation for T < T g and T > T m and to the theoretical Simha‐Somcynsky equatio…
Abstract Tensile specimens of isotactic polypropylene, initially crystallized in the β‐form with high purity, were tested at various temperatures. It was observed by WAXD that the most important phenomenon occurring in the course of a tensile test is the β‐smectic transformation for specimens drawn at lower temperatur…
The hysteresis effects of fluids confined in porous media are studied by means of a new microscopic model. We consider a slitlike pore of infinite area and finite height. In contrast to the unbounded parallel-plate case, the new model allows the formation and the disappearance of curved menisci at the open ends of the…
The distribution of cations between octahedral and tetrahedral sites in Fe3O4-FeAl2O4, Fe3O4-MgFe2O4, and Fe3O4-MgAl2O4 solid solutions has been detrmined in situ at 600°C to 1400°C and 1-atm pressure. The joint Fe3O4-MgFe2O4 fits reasonably well to either the simple constant KFe2+-Fe3+Cd and KMg-Fe3+Cd model (Navrots…