Materials Literature
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We present a simple sp 3 s* tight-binding model for use in calculating the band structures of single-walled carbon nanotubes. The 2s, 2p x , 2p y , 2p z , and s* orbitals of each carbon atom are used as the basis set for expressing the tight-binding model, and the interatom interaction between neighbouring sites is fu…
Abstract This paper is devoted to a numerical method able to help the determination of the bifurcation threshold in non‐linear time‐independent continuum mechanic problems. First, some theoretical results about uniqueness are recalled. In the framework of the large‐strain assumption, the differences between the classi…
2398-2399
Methods to chemically passivate the surfaces of amorphous-carbon films (a-C) produced by dc magnetron sputtering were studied. The chemical composition of carbon surfaces produced via sputtering are dependent upon the environment to which the carbon is exposed immediately following deposition. When the sputtered film…
We describe in detail a method by which to establish the magnetic anisotropy of thin ferromagnetic films on strongly paramagnetic substrates that are slightly anisotropic. The film that we consider is composed of the much studied manganite La0.7Ca0.3MnO3 and the substrate is NdGaO3, a good lattice match. Below a Curie…
Non-linear susceptibilities for use in describing the second-harmonic generation (SHG) recently observed in the hexagonal manganites RMnO 3 (R = Sc, Y, Ho, Er, Tm, Yb, Lu) below the Néel temperature T N are derived. Their explicit expressions show that they should give rise to quite different spectra according to whet…
Low-temperature-adapted archaea are abundant in the environment, yet little is known about the thermal adaptation of their proteins. We have previously compared elongation factor 2 (EF-2) proteins from Antarctic (Methanococcoides burtonii) and thermophilic (Methanosarcina thermophila) methanogens and found that the M.…
Vitreous selenium is used extensively for light detection. Its photoconducting properties are altered by structural relaxation near room temperature. X-ray diffraction, densiometry, and calorimetry are used to determine the change of the glass state during relaxation. Annealing for 24 h at 300 K increases the density…
We propose a molecular thermodynamic framework to describe liquid–liquid equilibria of hyperbranched polymer solutions. The model is based on the lattice cluster theory and the hydrogen-bonding model. We examine phase behaviors of hyperbranched polymer solutions in the effect of a branched structure and hydrogen bondi…
The longitudinal sound velocity v s ( T ) has been measured for La 1- X Ca X MnO 3 crystals, and anomalous softenings of v s ( T ) have been observed at the peculiar Ca concentrations of X =0.19 and X =0.82. For the X =0.19 sample, in which the ferromagnetic (FM) metallic phase competes with the FM insulating phase wi…
The hysteresis of composite systems consisting of nanosized ferromagnetic particles embedded in a nonmagnetic metal matrix is studied using the Monte Carlo method. In the model, the nanosized particles are assumed to be single domain and to possess random uniaxial anisotropy. The particles are well dispersed so that t…
Two crystal structures of human ornithine transcarbamylase (OTCase) complexed with the substrate carbamoyl phosphate (CP) have been solved. One structure, whose crystals were prepared by substituting N-phosphonacetyl-L-ornithine (PALO) liganded crystals with CP, has been refined at 2.4 A (1 A=0.1 nm) resolution to a c…
The effect of nitrogen addition on the structure and nanomechanical properties of tetrahedral amorphous carbon, tα-C, has been studied. The tα-C films were grown on Al 2 O 3 -TiC substrates by reactive pulsed KrF excimer laser ablation of graphite targets at a laser fluence of 10 J cm -2 . Nitrogen contents up to 19 a…
The effect of pressure on the crystal structure of HfW2O8 has been investigated by neutron powder diffraction. At a hydrostatic pressure of 0.62 GPa at room temperature the cubic material transforms, with a 5% reduction in volume, to the same orthorhombic phase that is seen in the isostructural compound ZrW2O8 above 0…
The magnetic and electronic properties of Fe-, Co-, Ni-substituted La0.7Ca0.3MnO3 were studied. Ferromagnetic–paramagnetic and metal–insulator transitions were significantly affected by Mn-site substitution although no observable differences were found in their crystal structures from x-ray diffraction analysis. Valen…
Radiation damage and the nature of the metamict state in natural zircons were studied and analysed using reflection and absorption infrared spectroscopy. IR bands of crystalline zircon in the far infrared region remain detectable in highly metamict samples. This suggests that some local order or short-range order pers…
This work focuses on the structural and magnetic characterization of arrays of cobalt nanowires, with diameters in the range 100–400 nm and lengths of L⩽6 μm, produced by electrodeposition in polycarbonate membrane pores. Diffraction patterns of Co nanowires indicate that Co is stabilized in the hcp structure with a p…
A multiple-shell model is presented for infinitesimal axially compressed buckling of a multiwalled carbon nanotube embedded within an elastic matrix. In contrast to an existing single-shell model which treats the entire multiwalled nanotube as a singlelayer elastic shell, the present model assumes that each of the nes…
Skutterudite (CoSb3 and IrSb3) thin films of high phase purity and crystallinity have been prepared by pulsed laser deposition. It is found that while the crystallinity of the films increases with increasing temperature, the phase purity decreases due to antimony volatility. The skutterudite phase can be stabilized to…
A room-temperature structural model of titanium pyrophosphate, TiP(2)O(7), has been determined from synchrotron X-ray data. The structure consists of TiO(6) octahedra and PO(4) tetrahedra sharing corners in a three-dimensional network. The PO(4) tetrahedra form P(2)O(7) groups connecting the TiO(6) octahedra. The 3 x…