Materials Literature
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A Ni8 cube, assembled with twelve bridging μ-violurato ligands, is present in 1 (H3vi = violuric acid). The oximate groups of the ligands lie along the edges of the cube, connecting the metal ions in an unprecedented trans conformation (see picture, • Ni) and mediating a strong antiferromagnetic coupling between the…
Dielectric permittivity studies of Na0.5Bi0.5TiO3 single crystals in a broad range of frequency up to 10 MHz and temperature 300—823 K are reported. In this temperature range dielectric dispersion below 1 MHz has been found. The obtained data were fitted to the Cole-Cole relation. The mean relaxation time τ is strongl…
A monomer with reactive double bonds was mixed with a liquid crystal and polymerized under UV irradiation in various phases of the liquid crystal. The polymer networks formed are found to be anisotropic and fiber-like, if the monomer is polymerized in an oriented liquid crystal state. The orientational order of the po…
Quantum paraelectrics are incipient ferroelectrics whose transition is hindered by the zero-point quantum motion. Recently however, electronparamagnetic-resonance measurements uncovered a phase-transition-like anomaly in the quantum paraelectric SrTiO3 at T q ≈ 37 K. The observed line shifts are accompanied by no meas…
We have studied the effects of suction air pressure on the structural parameters and mechanical properties of yarn. Changing the amount of suction air pressure improves the fiber extent in yam and yarn appearance. Therefore, photographic and fiber tracing methods are used to evaluate, respectively, yam appearance and…
Sonochemistry arises from acoustic cavitation; the formation, growth, and implosive collapse of bubbles in a liquid. The implosive collapse of bubble generates localized hot spot; temperature of similar to 5000 K and pressure of similar to 1800 atm, with heating and cooling rates that exceed 10(7) K/s. Using these ext…
In this article, we report the first experimental observation of resonance light absorption by a fabricated subnanostructure and high frequency rectification in the range corresponding to that of visible light. The subnanostructure consists of a parallel dipole antenna array. A resonance peak signal of short circuit c…
We have nickel doped boron carbide grown by plasma enhanced chemical vapor deposition. The source gas closo-1,2-dicarbadodecaborane (ortho-carborane) was used to grow the boron carbide, while nickelocene [Ni(C5H5)2] was used to introduce nickel into the growing film. The doping of nickel transformed a p-type, B5C mate…
It is generally found that grinding transverse to the tensile stress direction in flexure bars subjected to four-point bending results in a lower strength compared to grinding in the longitudinal direction. In the present study, standard flexure specimens made from a reaction-bonded and a sintered reaction-bonded sili…
The electrochemical characteristics of fullerenes and fluorinated fullerenes have been investigated by cyclic voltammetry and galvanostatic discharge using solid‐state lithium cells , and , MEP‐7 = a polyphosphazene derivative). In the cyclic voltammograms of and , the first half‐wave potential of is found to be 0.2 V…
Analysis of the active-site residues of a fully functional chorismate mutase representing the N-terminal 113 amino acids of the Escherichia coli P-protein suggests that Lys39 and Gln88 play critical roles in catalyzing the rearrangement of chorismate to prephenate. Five site-directed mutants at these positions have be…
Using a polarizing optical microscope in conjunction with a charged-coupled device camera system, the domain microstructural evolution with respect to temperature in all three phases of BaTiO3 was studied. Along a (001) oriented section the domains in the tetragonal phase form 90° domain patterns in an ‘a—a’ configura…
Expression of the Kdp system sensitizes cells to methylglyoxal (MG) whether this electrophile is added externally or is synthesized endogenously. The basis of this enhanced sensitivity is the maintenance of a higher cytoplasmic pH (pHi) in cells expressing Kdp. In such cells, MG elicits rapid cytoplasmic acidification…
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…