Materials Literature
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Polyrotaxane‐like structures consisting of macrocycles trapped to form a polymeric network (see Figure) have been synthesized using a pre‐assembling principle. The synthesis and electrochemical characterization of thin films are described. In addition to the classical properties of organic conducting polymers, the ass…
Novel calcium phosphate ceramics were fabricated by hot‐pressing fibrous products extracted from crystallized products of calcium ultraphosphate glasses by aqueous leaching. The ceramics were dense materials with a relative density of >95%; these ceramics were composite materials that consisted of β‐Ca(PO 3 ) 2 fib…
Abstract Microcrystallites of (NH4)3PW12O40 self-assembled to form symmetric dodecahedral aggregates (ca. 0.5–6 μm in size) in which the microcrystallites joined together with the same crystal orientation, by controlled deposition of NH4 salts from a heated aqueous solution of H3PW12O40. These aggregates were highly p…
British Airways has carried out radiation monitoring in Concorde for more than 20 years and has used a heuristic model based on data quoted by the National Aeronautics and Space Administration (NASA) to model radiation exposure in all longhaul fleets. From these data it has been calculated that no flight deck crew wou…
Colominic acid is a capsular homopolymer from Escherichia coli K1 composed of alpha (2-8)-linked N-acetyl-D-neuraminic acid (NeuAc) residues. Recently, we have described that NeuAc synthesis in this bacterium occurs through the action of NeuAc lyase (EC 4.1.3.3) [ Rodríguez-Aparicio, Ferrero and Reglero (1995) Biochem…
A novel pathway for the synthesis of poly-3-hydroxybutyrate has been engineered by simultaneous delivery of two genes into insect cells (Spodoptera frugiperda) by use of individual baculovirus vectors. This system includes expression of a dehydrase-domain mutant rat fatty acid synthase cDNA and the phbC gene encoding…
Monolithic ceramics, such as silicon nitride, silicon carbide, aluminum nitride, zirconia, and alumina; particulate- and whisker-reinforced ceramic-matrix composites; and ceramic coatings pose difficulties in machining. Because of the high hardness and low toughness of these materials, diamond grinding is often the me…
Polycarbonate (PC) can be easily crystallized by injecting a very dilute benzene solution of PC directly into liquid nitrogen, and then freeze-drying to remove the solvent. The crystallinities of these prepared samples were characterized by wide-angle X-ray diffraction (WAXD). The results of WAXD studies showed that t…
The present work indicates through thermodynamic considerations that YLiO 2 additive is beneficial for low‐temperature sintering of AlN ceramics. Pressureless sintering of commercially available AIN powders with simultaneous additions of YLiO 2 and CaO resulted in materials with high thermal conductivity (170 W·m –1 ·…
The main objective of this paper is to report on a newly developed three phase TCR model for SVC which is based on the use of harmonic switching vectors and discrete convolutions. This model is amenable to direct frequency domain operations and provided a fast and reliable means for assessing 6- and l2-pulse TCR plant…
In order to improve wettability of polycarbonate to triple distilled water, an Ar+ ion and an oxygen ion were irradiated on a polycarbonate (PC) surface under various oxygen flow rates. Doses of ions were changed from 5×1014 to 5×1016 ion/cm2 in a range from 500 eV to 1.5 keV energy by a broad ion beam source. Wetting…
Aqueous solutions of Al 3+ and Fe 3+ nitrates were pyrolyzed to produce (Al,Fe) 2 O 3 amorphous solid solutions with up to 50 mol% Fe 2 O 3 . Following subsequent heat treatments, all compositions first crystallized to γ‐(Al,Fe) 2 O 3 and those with ≥20% Fe 2 O 3 ultimately partitioned into a mixture of A1 2 O 3 and F…
The Fermi pencil-beam approximation describes the broadening of a monoenergetic, nearly monodirectional particle beam in an optically thick system in which the mean scattering angle is small and large-angle scattering is negligible. This physical problem has applications in such diverse fields as astrophysics, materia…
The corrosion films on iron in aqueous carbonate/bicarbonate solutions were studied as a function of concentration, pH, and temperature by using the technique of surface‐enhanced Raman spectroscopy with electrodeposited silver. Both and were detected in the surface oxide film at prepassivation potentials. Iron carbona…
A phenoxynaphthacenequinone forms a densely packed monolayer together with 1-tetradecanethiol on a gold electrode. The assembly can be reversibly switched to enable amperometric transduction of an optical signal. In the diagram on the right the current is switched off by irradiation with UV light.
Abstract The polymer systems are discussed in the framework of the Landau‐Ginzburg model. The model is derived from the mesoscopic Edwards Hamiltonian via the conditional partition function. We discuss flexible, semiflexible and rigid polymers. The following systems are studied: polymer blends, flexible diblock and mu…
Partial substitution of ammonium polyphosphate (APP) by manganese dioxide (MnO2) in polyamide 6 (PA-6) fire retarded with 20% of APP strongly increases the fire retardant effect. ‘Linear pyrolysis’ experiments, which are modified cone calorimeter tests, show an increase in the amount and an improvement of the shieldin…
Infrared spectroscopy has been coupled with the polarization modulation technique in order to characterize the molecular orientation in films of azopolymers irradiated in situ with polarized visible light. The results obtained on disperse red 1-containing amorphous azopolymer (pDR1A) demonstrate the high efficiency of…
The ion contamination in twisted nematic liquid crystals should be limited to assure good electro-optical performance of AM-LCDs. Today, pure liquid crystal mixtures are produced, though little information is available on long term stability, and on the kind of ions that contaminate the liquid crystal. The first step…
Recent advances in the theory of characteristic X-ray emission from crystals under dynamic electron diffraction conditions are used in developing a new fully quantitative statistical method for atom location by channelling-enhanced microanalysis (ALCHEMI). Limitations imposed by delocalization, disorder and occupancy…