Materials Literature
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Superplastic forming is an industrial process which is currently limited by the relatively slow strain rates, and consequent long forming times, associated with the fabrication of each superplastic component. Any expansion of this technology requires both the processing of materials capable of exhibiting high strain r…
Surface modification of low-density polyethylene (LDPE) and polytetrafluoroethylene (PTFE) films via graft copolymerization with acrylic acid (AAc), Na salt of styrenesulfonic acid (NaSS), N,N-dimethylacrylamide (DMAA), 2-(dimethylamino)ethyl methacrylate (DMAEMA), glycidyl methacrylate (GMA), acrylamide (AAm) and 3-d…
A molecular dynamics (MD) study of sodium phosphate glass was performed in order to determine the short range structure. The structure of the glass was analysed and the results compared to those found experimentally using X-ray diffraction. The results from the simulation revealed two phosphorus–oxygen interatomic bon…
This literature review identifies ageing factors and their effects on polymeric insulators. According to their nature, these factors are classified as electrical, mechanical, ultra-violet radiation, chemical, thermal and water ingress. The effects are manifested as external or internal damage with loss of electrical a…
A new type of spin-valves using perovskite antiferromagnets, MFeO/sub 8/ (M=Y,La,Pr,Nd,Sm), as the pinning layers was developed. These spin-valves are composed of MFeO/sub 8//P/Cu/F, where P and F are the pinned and free layers, respectively, and were prepared by sputtering on Si or glass substrates. Among these spin-…
Rhenium-(V), -(VI) and -(VII) complexes of the [α2-P2W17O61]10– isomer, a mono-lacunary derivative of the [α-P2W18O62]6– (Wells–Dawson) ion have been prepared and characterized by multinuclear NMR spectroscopy, electrospray mass spectrometry and electron paramagnetic resonance spectroscopy, among other techniques. The…
All articles of this category 3,4-Dialkoxypyrroles are obtained in four steps from commercially available 2,5-dimethoxy-2,5-dihydrofuran ( 1 ). The dihydrofuran 1 is first oxidized by KMnO 4 to the diol 2 which is bisalkylated to 3a-d . Reaction of the in situ generated dialdehydes with a primary amine affords the N -…
Afin de developper un systeme a liberation controlee des principes actifs administres par voie orale, nous avons synthetise un reseau semi-interpenetre a base de chitosane reticule par le glyoxal et de polyoxyethylene. La caracterisation du chitosane a ete realisee par la determination de son degre de deacetylation pa…
The molluscicidal activity of a cardenolide (cardiac glycoside) extract from Pergularia tomentosa (L.) (Asclepiadaceae), methomyl, and methiocarb was evaluated against the land snail Monacha obstructa (Ferussac) at 25 degress C. The LD50 value of the plant extract after 24 h of treatment was 60.9 mug/snail, whereas th…
We report measurements of the electronic conductivity and partly the electronic mobility and optical absorption spectra in alkali halide melts containing tantalum or niobium chloride and oxychloride complexes in different oxidation states. Both electrochemical impedance spectroscopy and the Wagner–Hebb polarization me…
The first example of monomeric bidentate citrato oxomolybdate(VI) and -tungstate(VI) have been prepared by cleavage of dimeric citrato molybdate and tungstate.
Ten novel columnar liquid crystals, [octakis(4-alkoxyphenyl)tetrapyrazinoporphyrazinato]metal(II) (abbreviated as (C n O) 8 –M; n = 10, 12; M = Cu, Ni) and [octakis(3,4-dialkoxyphenyl)tetrapyrazinoporphyrazinato]metal(II) (abbreviated as (C n O) 16 –M; n = 8, 10, 12; M = Cu, Ni), have been synthesized and characterize…
Two ferrocene-containing low molar mass organosiloxane liquid-crystalline materials have been synthesised and their phase-transition behaviour investigated. The ω-unsaturated ferrocene precursor was hydrosilylated by addition of pentamethyldisiloxane or heptamethyltrisiloxane in the presence of platinum divinyltetrame…
This paper examines the dynamic process of hairiness formation in worsted ring spinning. A special CCD camera was used to observe the fibre behaviour in the spinning triangle. The formation mechanisms of leading, trailing, looped, and wild hairs are demonstrated with a series of photos. Several unique features on hair…
Diazadithiafulvalenes act as excellent electron donors to arenediazonium salts. The diazadithiafulvalenium radical cations trap primary carbon radicals successfully. However, the diazadithiafulvalenium salts which form, undergo rapid ring fragmentation in contrast to their tetrathia counterparts.
A blue luminescent emission band (440 nm) has been optimised in Y1 – xBixNbO (x = 0.005) for low voltage phosphor applications. The material has useful properties when compared to a commercially available phosphor. The role of the Bi3+ ion dopant is discussed in this lattice and in the related Gd1 – xBixNbO4 lattice.…
The first crystal structure of an inorganic pyrophosphatase (S-PPase) from an archaebacterium, the thermophile Sulfolobus acidocaldarius, has been solved by molecular replacement and refined to an R-factor of 19.7% at 2.7 A. S-PPase is a D3 homohexameric protein with one Mg2+ per active site in a position similar to,…
The ground states of La 1- x Ca x MnO 3 change from double-exchange-associated conducting ferromagnets at x <0.50 to charge-ordered antiferromagnets at x >0.50 even when x is varied only slightly around 0.50. We have performed a careful study of the electrical and magnetic properties of these materials for a range of…
We have considered the dynamical evolution of cellular patterns controlled by a stochastic Glauber process determined by the deviations of local cell topology from that of a crystalline structure. Above a critical temperature evolution is towards a common equilibrium state from any initial configuration, but beneath t…
Motivations leading to lowering the primary beam energy in the SEM are summarized and arguments are presented in favour of extending the operation range down to tens and units of eV. Possibilities to produce beams at low energies below 1 keV and very low energies below 50-100 eV are reviewed, particularly the principl…