Materials Literature
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We prepared a Tm-doped glass composite with a Nd-doped layer as a model 1.4-mum thulium-doped fiber amplifier (TDFA) to investigate the effect of energy transfer on the emission spectra of the composite. The competitive 0.8-mu;m emission from the Tm:(3)H(4) level, which had a branching ratio ten times larger than that…
Models for environment-assisted cracking (EAC) predominantly consider anodic reaction-based processes for simulation of crack propagation. A limited number of models have been developed to evaluate crack initiation or fatigue crack velocities by relatively simple analytical equations. Considerable effort also has been…
The morphology of single native cellulose (flax) fibres was investigated by means of simultaneous small-angle scattering and fibre diffraction using an X-ray microbeam. The azimuthal broadenings both of the equatorial small-angle scattering streak and of Bragg reflections are found to be due to a misalignment of the c…
The flow pattern induced by ultrasonic vibration in a water vessel is investigated experimentally using several liquids. In tap water, vortex streaming of cavitation bubbles around the pressure node of a standing wave occurred because of the large number of cavitation bubbles generated by the ultrasonic vibration. Aco…
New techniques for measuring surface degradation are applied to the study of surface tracking resistance of materials intended for outdoor use. Cycloaliphatic epoxy resin (CAE) with 200 pph silica powder was aged under accelerated conditions for 100 h (100 to 250/spl deg/C) and then its tracking resistance was assesse…
The chemical reactions between nitrogen dioxide vapour and diphenylamine (DPA), some of its nitro/nitroso derivatives and between their consecutive products have been studied at temperatures of about 23 °C, whereby cellulose was used as substrate material. The following stabilizer compounds were used as starting compo…
The physical gelation of organic solutions of 3,4,5-tris(octyloxy)benzamide at ambient temperature, subsequent to shock-freezing in liquid nitrogen is reported. Microscopic investigations of the morphology of these “supramolecular organogels” suggests the occurrence of networks of rod-like crystals with diameters betw…
Phenyl side chains were introduced to poly(butylene succinate) and poly(ethylene adipate) by the polymerization of the respective monomers in the presence of mandelic acid. The increasing content of the phenyl side chains decreased the melting temperature and the crystallinity but increased the glass-transition temper…
We describe a web server, which provides easy access to the SLoop database of loop conformations connecting elements of protein secondary structure. The loops are classified according to their length, the type of bounding secondary structures and the conformation of the mainchain. The current release of the database c…
Abstract Mineralogical studies were performed on authigenic clay minerals of mudrocks, sandstones, and bentonites from 38 boreholes in the Late Permian coal measures of the Bowen Basin. Clay-mineral separations of samples from the northern Bowen Basin consist mainly of (Reichweite, R) R = 1 and R ≥ 3 interstratified i…
The effectiveness of calcite growth inhibition by copper(II) ions depends not only on copper concentration but also on calcite supersaturation and solution composition (i.e., pH, carbonate concentration, etc.). This paper presents an investigation of the effect of solution composition; an earlier paper (Parsiegla and…
We propose a mechanism of nodeless d-wave superconductivity in a quasi-one-dimensional organic superconductor under anion order. It is shown that a split of the Fermi surfaces due to the anion order eliminates the line nodes of a d-wave gap function on the Fermi surfaces, and a small finite energy gap appears in the q…
Monophosphate tungsten bronze with pentagonal tunnels (PO2)4(WO3)2m are low-dimensional materials with charge density wave (CDW)-type electron instabilities. Two forms of the structure can thus be expected for all the members of the series: a low-temperature form (LT) corresponding to the CDW state and a high-temperat…
Abstract A brief review is given of the ways in which the local structure in glass can influence the microstructure that supports ionic transport. This in turn contributes to the co-operative nature of ion dynamics and ways in which this underpins the ‘mixed alkali effect’ are discussed. Glass microstructure too is ex…
Abstract The crystal structure of the high-pressure phase-II of cristobalite has been solved by neutron diffraction (space group P 2 1 / c , a = 8.3780(11) Å, b = 4.6018(6) Å, c = 9.0568(13) Å, β = 124.949(7)°, at P = 3.5 GPa). This phase corresponds to a distortion of the high-temperature cubic β-phase, rather than o…
Low‐oxygen silicon carbide fibers (Hi‐Nicalon) were oxidized at temperatures from 1073 to 1773 K under an oxygen partial pressure of 0.25 atm. The strength of the unoxidized core was practically unaffected by the oxidation temperatures. The strength of the as‐oxidized fibers with an SiO 2 film decreased markedly with…
Proton, deuteron, and carbon NMR methods were applied to study various isotopic species of supercooled and glassy propylene carbonate. The molecular diffusion was investigated via static field gradient diffusometry and yielded evidence for a particularly pronounced enhancement of the translational over the reorientati…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTADDITION / CORRECTIONThis article has been corrected. View the notice.Highly Efficient Complexations of a Porphyrin Dimer with Remarkably Small Differences between Nucleosides and Nucleotides/The Predominance of Stacking Interactions for Nucleic Acid ComponentsMallena…
The uniaxial anisotropy energy of arrays of submicronic (30--500 nm) Ni wires synthesized by electrodeposition into cylindrical pores of track-etched polycarbonate membranes is studied as a function of temperature. At room temperature, the uniaxial anisotropy is equal to the shape anisotropy whereas an additional cont…
With 1999 marking the 100th anniversary of the discovery of organic photochromic compounds1, it is a fitting time to reflect back on commercial uses that have developed from this interesting class of organic compounds over the years. From the many applications that have been proposed, including security devices and op…