Materials Literature
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Normal arteries have properties which match the low output impedance of the heart to the high peripheral impedance. These properties can be assessed in terms of compliance (% diameter change per unit pressure change) as well as by other haemodynamic parameters. Experiments were designed using vein, Dacron and expanded…
Measurements are presented in this paper of the pulsation amplitude of an individual air bubble that is levitated in a glycerine–water mixture by a stationary acoustic wave operating at a frequency of 22.2 kHz. Observations of the bubble pulsation for a wide range of bubble sizes demonstrate the existence of the n=2 h…
Eight new cardenolide glycosides, 19-deoxyuscharin (1b), 4′β-hydroxygomphoside (1k), 3′-didehydrogomphoside (1d), 3′-epigomphoside (1e), 3′-epiafroside (2e), 3′-epigomphoside 3′-acetate (1f), 3′-didehydroafroside (2d), and 3′-epiafroside 3′-acetate (2f), have been isolated from Asclepias fruticosa R. Br. The structure…
Abstract
The synthesis of tetra-arylporphyrins, for studies in solar energy conversion, is described. They are derived from 5,10,15,20-meso-tetrakis(4-hydroxyphenyl)porphyrin (4) which, in basic media, forms a green intermediate that is probably the tetraphenoxide (6). The porphyrins (10) and (13), were synthesised as prospect…
Dielectric investigations (65 K – 900K) and DTA investigations (300 K - 900K) have been carried out for AgNb, -Ta solid solutions. A series of anomalies were found in the temperature-dependence of the dielectric constant and loss tangent, as well as anomalies in the DTA curves associated with phase transitions. From t…
This paper presents torsional test results for six metals subjected to large shear strains and high strain rates. Included are 2024-T351 aluminum, 7039 aluminum, low alloy steel, S-7 tool steel, tungsten alloy and DU-.75Ti (Depleted Uranium). The specimens are strained to fracture at strain rates from quasi-static to…
L'ordre à courte distance dans les verres peut être étudié par différentes spectroscopies, sensibles soit à des facteurs géométriques (coordinance, distance métal-oxygène) soit de nature plus chimique (degré d'oxydation, covalence métal-oxygène). Nous présentons les résultats obtenus principalement sur les verres sili…
Abstract Crosslinking of 4,4′(bismaleimido)diphenyl ether (BM) was investigated in presence of bis( m ‐aminophenyl)methylphosphine oxide (BAP), tris( m ‐aminophenyl)phosphine oxide (TAP), diaminodiphenyl ether (E) and 3,3‐bis(p‐aminophenyl)phthalide (AP). These crosslinked resins were examined for thermal stability by…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNatural ferric ionophores: total synthesis of schizokinen, schizokinen A, and arthrobactinByung Hyun Lee and Marvin J. MillerCite this: J. Org. Chem. 1983, 48, 1, 24–31Publication Date (Print):January 1, 1983Publication History Published online1 May 2002Published inissue 1 J…
Alumina single crystals were deformed in compression along the c axes at T= 625 to 1373 K. Large‐scale deformation by rhombohedral twinning was observed at a constant resolved shear stress of only 12.6 MPa between ∼900 and 1373 K. Below 900 K, the twinning stress for specimens with ground surfaces rose rapidly to 227…
Tetrathiafulvalenes. XIX. Synthesis and Properties of Electron Conducting Poly‐Dithiolene Complexes with Ethylene Tetrathiolat and Tetrathiafulvalene Tetrathiolat as Bridge Ligands [1,3]‐Dithiolo[4,5‐d]‐1,3‐dithiol‐2,5‐dione 7 and 5‐(5‐oxo[1,3]‐dithiolo[4,5–d]1,3‐dithiole‐2‐ylidene)[1,3]‐dithiolo[4,5–d]1,3–dithiol‐2‐o…
The gene for the MspI modification enzyme from Moraxella was cloned in Escherichia coli using the plasmid vector pBR322. Selection of transformants carrying the gene was based on the resistance of the modified plasmid encoding the enzyme to cleavage by MspI. Both chromosomal and plasmid DNA were modified in the select…
Abstract A number of samples of poly( D , L ‐lactic acid) (PLA) with weight‐average molecular weights M̄ w in the range 15,000–350,000 were prepared by a ring‐opening polymerization. The molecular weight distributions (MWDs) of these samples were determined by gel permeation chromatography (GPC). The method involves a…
The respiration of [35S] sulphate to [35S] sulphide by hydrogen-grown sulphate-reducing bacteria was used as a sensitive indicator to monitor cathodic hydrogen utilisation. The transient depolarisation of both mild steel and X65 pipeline steel electrodes, a rise in pH and a burst of hydrogen [35S] sulphide production,…
Anion voidage and anion void lattice formation in electron irradiated (100 keV–1 MeV) fluorite (CaF2) has been investigated by in situ transmission electron microscopy. At low fluences (≲1 dpa) the damage consists of randomly distributed anion voids and large bubble-like defects associated with fluorine gas. At higher…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhosphorus NMR study of solid amorphous calcium phosphateJames Tropp, Norman C. Blumenthal, and John S. WaughCite this: J. Am. Chem. Soc. 1983, 105, 1, 22–26Publication Date (Print):January 1, 1983Publication History Published online1 May 2002Published inissue 1 January 1983…
Nous considérons un solide poreux, ou un gel, saturé par un système fluide à deux composants, A, B, dans le domaine de température où A et B démixent; l’épaisseur 03BE de l’interface est supposée plus petite que la taille des pores. Le solide préfère être en contact avec la phase riche en A. Mais, si l’on fait décroît…
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A theoretical and experimental study of potential gradients in crevices between a piece of steel and an insulating coating has revealed that the condition of the steel surface and the potential of the steel at the coating holiday have important effects on the potential gradient. Holiday potentials more negative than t…