Materials Literature
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The large-magnetoresistance compounds ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ have been studied using specific heat, sound velocity $(v)$, and electron diffraction. For $0.63\ensuremath{\le}x\ensuremath{\le}0.67$ charge ordering is observed at 260 K and accompanied by a dramatic $(>10%…
Transparent zinc oxide (ZnO) films has been cathodically deposited on conductive glasses from a simple aqueous zinc nitrate electrolyte kept at 335 K. ZnO films prepared had a wurtzite structure and exhibited an optical band gap energy of 3.3 eV which is characteristic of ZnO. A 2-μm-thick ZnO film with an optical tra…
The macroscopic four-wave mixing susceptibility is separated into a geometrical and a molecular factor using vector coupling algebra. The geometrical factor for isotropic samples is given explicitly for collinear circularly polarized beams and for an arbitrary geometry of linearly polarized beams. The result for four…
We examine sequences of dense packings of $n$ congruent non-overlapping disks inside a square which follow specific patterns as $n$ increases along certain values, $n = n(1), n(2),... n(k),...$. Extending and improving previous work of Nurmela and Östergård where previous patterns for $n = n(k)$ of the form $ k^2$, $…
Alcaligenes latus, a growth-associated PHB producer, was cultivated by a pH-stat modal fed-batch culture technique to attain high PHB productivity. Both sucrose solution and inorganic medium were fed in conjunction with the supply of ammonia solution which serves as a nitrogen source and as a means of pH control. Comp…
Molecular sieves from a building kit?! Gallium siloxanes of the type shown (substituents on the Si and Ga atoms have been omitted for clarity), which have been synthesized and structurally characterized for the first time, add to the number of molecules that can be considered for the directed synthesis of zeolite-like…
Scanning tunneling microscope (STM)-induced selective bond breaking in individual molecules and conventional STM imaging are combined to determine the nature of chemisorbed O 2 species formed during the initial stages of silicon (111)-(7×7) oxidation. A selective atomic-scale modification mechanism that involves disso…
Fast and efficient—energy is transferred within a supramolecular system from the light-harvesting aggregate of zinc chlorins to the coaggregated metal-free bacteriochlorin chromophore (see schematic representation below). This is a first example of a self-assembled light-harvesting antenna that efficiently transfers l…
Some materials exhibit large changes in electrical resistance in the presence of a magnetic field, and this change can be used in applications from sensor technology to magnetic data storage. In their Perspective, Rao and Cheetham discuss magnetoresistance in perovskite manganates, where the effect is unusually strong…
Subpicosecond photoexcitation of CdS/HgS/CdS quantum dot quantum well nanoparticles at wavelengths shorter than their interband absorption (390 nm) leads to a photobleach spectrum at longer wavelengths (440−740 nm). The photobleach spectrum changes and its maximum red-shifts with delay time. These results are explaine…
In this work, the critical temperature (Tc) of a series of polymeric superconducting systems is determined which, sintered or not, are obtained through the incorporation of the superconducting ceramic YBaCuO into two extrinsic conducting polymer systems: PVDF/PS/carbon black and PVDF/PS/copper. In addition, the diamag…
CF 4 and O 2 glow discharge treatment of biaxially oriented polypropylene film results in the surface incorporation of fluorine and oxygen atoms, respectively, together with an increase in surface roughness. The stability and extent of substrate modification have been investigated by X-ray photoelectron spectroscopy (…
The boron-substituted MCM-41 was hydrothermally synthesized using Na 2 B 4 O 7 and H 3 BO 3 as boron sources. The influence of the nature of the boron source on the textural properties as well as the stability of MCM-41 structure and the state of boron upon different procedures such as NH 3 treatment, ion-exchange, an…
Graft polymerizations of methyl acrylate (MA) onto granular cornstarch were carried out in water with both ferrous ammonium sulfate/hydrogen peroxide (FAS/H2O2) and ceric ammonium nitrate (CAN) initiation. Starch concentrations were 10, 20, and 30% in water, and the amount of MA used was either 0.5, 1, or 2 mol per AG…
In-situ Cd K-edge EXAFS analysis of colloidal CdS nanocrystallites (CdS-DMF, mean diameter 3.5 nm, hexagonal) prepared by reacting Cd 2+ and H 2 S in N, N -dimethylformamide (DMF) was performed to clarify their microscopic surface structure in solution. The structure of the [Cd 4 (SC 6 H 5 ) 10 ] 2- cluster (Cd 4 -clu…
The use of molecular and continuum emission spectra from multiple bubble (MB) and single bubble (SB) sonoluminescence (SL) is explored as a probe of bubble temperature during cavitational collapse. It is proposed that molecular and continuum SL arise from different chemical pathways, which occur during discrete interv…
Heat of immersion (Δ H im ) data are frequently used to investigate the surface characteristics of solids. In this study, the relationship between the heat of immersion and the contact angle is established from first principles for hydrophobic powders. The heat of immersion of three fluorinated carbons in water is obt…
Mechanical properties, such as tensile and flexural properties, as well as impact behavior of silver-powder-filled isotactic polypropylene composites were investigated in the composite composition range of 0–5.6 vol% of Ag. Tensile modulus, strength, and elongation at break decreased with incorporation of silver and a…
Variations in the band structures of C60-polymers are studied, when conjugation conditions and the electron number are changed. We use a semiempirical model with the Su-Schrieffer-Heeger type electron-phonon interactions. In the neutral one-dimensional C60-polymer, electronic structures change among direct-gap insulat…
Since the early work on grain boundary relaxation by Kě in 1947, the grain boundary internal friction peaks were mostly measured by the free decay method as a function of temperature. The validity of this procedure is based on the assumption that the grain boundary relaxation. as a rate process, should obey the Arrhen…