The characterisation of the nature of silica in biological systems
The silica in some biominerals has been investigated by electron microscopy and i.r. and n.m.r. spectroscopy and has been shown to be amorphous and to contain many Si–OH units.
Materials Literature
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A single crystal of YALO3: Ce3+ as a fast scintillator in SEM
Abstract A new single‐crystal scintillator intended for applications in a scanning electron microscope (SEM) is presented. It is a single‐crystal disc of yttrium aluminium perovskite activated by trivalent cerium free of traces of Fe ions. The single crystals of YAlO 3 : Ce 3+ (YAP: Ce 3+ ) were prepared by the Czochr…
Consistency of fats: A review
Abstract The consistency of fats can be measured with the cone penetrometer (AOCS Method Cc 16‐60). Several suggestions have been made to convert readings of penetration depth into parameters such as yield value, hardness or hardness index. This may extend the usefulness of the method. Motor‐driven penetrating devices…
The density and pressure of helium in bubbles in metals
The energy shift of the He 11S0−21P1 transition, ΔE(n), can be used to determine the density, n, of He in bubbles in metals. A self-consistent band structure calculation for solid fcc He yields a linear relationship ΔE=C.n with C th=22 × 10−3 eV nm3. Systematic electron energy loss spectroscopy and transmission electr…
The effect of wall mechanical properties on patency of arterial grafts.
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…
Nonlinear oscillations of gas bubbles in liquids: An interpretation of some experimental results
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…
Cardenolide glycosides of the asclepiadaceae. New glycosides from asclepias fruticosa and the stereochemistry of uscharin, voruscharin and calotoxin
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…
Process of preparation and properties of ultra-high strength polyethylene fibers
Abstract
Synthesis of some new tetra-arylporphyrins for studies in solar energy conversion
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…
AgNb1−xTaxO3solid solutions‐dielectric properties and phase transitions
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…
Response of Various Metals to Large Torsional Strains Over a Large Range of Strain Rates—Part 2: Less Ductile Metals
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…
Structure of oxide glasses : spectroscopic studies of local order and crystallochemistry. Geochemical implications
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…
Addition polyimides. I
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…
Natural ferric ionophores: total synthesis of schizokinen, schizokinen A, and arthrobactin
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…
Rhombohedral Twinning in Alumina
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…
Tetrathiafulvalene. XIX. Synthese und Eigenschaften elektronenleitender Poly‐Dithiolenkomplexe mit Ethylentetrathiolat und Tetrathiafulvalentetrathiolat als Brückenliganden
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…
Cloning of the MspI modification enzyme. The site of modification and its effects on cleavage by MspI and HpaII.
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…
Characterization of poly(D,L‐lactic acid) by gel permeation chromatography
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…
Utilisation of Cathodic Hydrogen by Sulphate-Reducing Bacteria
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 the void superlattice in electron irradiated Caf2
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…