Materials Literature
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We report the growth by molecular beam epitaxy and the optical characterization of GaN films nucleated on a Si(111) surface that has been patterned by dry etching an ordered array of nanometer-scale pores prior to the growth. The etching is performed using an anodized aluminum oxide membrane as a mask. The nanopore ar…
Brillouin scattering measurements on the nanocrystalline cubic phase of ${\mathrm{BC}}_{2}\mathrm{N},$ the hardest known solid after diamond, have been successfully performed using the ``emulated'' platelet scattering geometry. We were able to measure both longitudinal ${(V}_{p})$ and shear ${(V}_{s})$ velocities inde…
We report the electrical properties of a single conducting polyaniline nanotube measured by a standard four-terminal technique. Camphor sulfonic acid doped polyaniline nanotubes were self-assembled by a template-free method. The directly measured conductivity of the single polyaniline nanotube is very high (∼31.4 S/cm…
Molecular dynamics simulations are performed to investigate the behaviour of helium atoms generated from tritium decay in perfect Cu crystals at 300 K. At the early stage just after a 3 He atom generation, the lattice structure is badly deformed and the local temperature rises considerably above 300 K. Single 3 He ato…
Direct heteroepitaxial growth of uniform stoichiometric CuInS2 (CIS) thin films on sapphire (0001) substrates has been achieved by radio frequency reactive sputtering. X-ray ω–2θ scans reveal that the sputtered layers grow in a (112) orientation with a chalcopyrite structure. A rocking curve full width at half maximum…
Structures of (FeO) x (P 2 O 5 ) 1− x glasses with 0.2 ≤ x ≤ 0.5 are studied by x-ray diffraction using high energy photons from a synchrotron. Scattering intensities are obtained up to Q max of 250 nm −1 . P–O, Fe–O and O–O first-neighbour peaks are well resolved in the pair distribution functions. Constant P–O coord…
Adapting metabolic enzymes of microorganisms to low temperature environments may require a difficult compromise between velocity and affinity. We have investigated catalytic efficiency in a key metabolic enzyme (dihydrofolate reductase) of Moritella profunda sp. nov., a strictly psychrophilic bacterium with a maximal…
Simple p–n junctions have been fabricated using a simple heteroepitaxial structure of La0.67Ca0.33MnO3−δ/Nb-doped SrTiO3. In such junctions, the La0.67Ca0.33MnO3−δ exhibits semiconductor behavior due to oxygen deficiency, whereas the Nb–0.7 wt %-doped SrTiO3 shows a metal behavior. These junctions demonstrate good rec…
The structural relaxation caused by the plastic deformation of polymer glasses is not yet fully understood. In particular, the size scale of the localized plastic relaxation events is currently unknown. In this work, the effect of molecular entanglement density on the shear activation volume of glassy polymers has bee…
We have examined the effect of monomer structure on amine−anhydride reactions at a polymer−polymer interface. The thermodynamic interaction parameter χ was varied by changing the backbone chemical structure, holding molecular weight constant. To eliminate the effects of mixing, experiments were performed with bilayer…
A magnetostructural correlation (conformational electron spin exchange modulation) within an isostructural series of biradical complexes is presented. X-ray crystal structures, variable-temperature electron paramagnetic resonance spectroscopy, zero-field splitting parameters, and variable-temperature magnetic suscepti…
The direct oxyfunctionalization of a model polyolefin, polyethylene- alt -propylene (PEP), was achieved utilizing a straightforward, mild process. In the presence of a manganese complex, manganese meso- tetra-2,6-dichlorophenylporphyrin acetate (Mn(TDCPP)OAc), imidazole, a phase transfer agent, and potassium peroxymon…
We have fabricated a p–n junction, consisting of p-type manganite (La0.7Sr0.3MnO3) and n-type ZnO layers grown on sapphire substrate. This junction exhibits excellent rectifying behavior over the temperature range 20–300 K. Electrical characteristics of La0.7Sr0.3MnO3 (LSMO) film in this heterostructure are found to b…
AlN films grown by gas-source molecular beam epitaxy were doped with different levels of Mn during growth. High resolution x-ray diffraction characterization revealed good crystallinity in single phase material, with lattice constant decreasing with increasing Mn concentration. Single phase AlMnN was found to be p typ…
The biosynthetic pathway of medium-chain-length (MCL) polyhydroxyalkanoates (PHAs) from fatty acids has been established in fadB mutant Escherichia coli strain by expressing the MCL-PHA synthase gene. However, the enzymes that are responsible for the generation of (R)-3-hydroxyacyl coenzyme A (R3HA-CoAs), the substrat…
As a result of a pseudosymmetry search, the double perovskite compounds Sr 2 MWO 6 (M = Ni, Zn, Co, Cu) were identified as good candidates for presenting Landau-type phase transitions at high temperatures. In the present work, the phases observed at different temperatures are reported and the phase transitions are dis…
The causality of waves propagating in a double-negative (DNG) metamaterial (epsilon (r)<0 and mu(r)<0) has been investigated both analytically and numerically. By considering the one-dimensional electromagnetic problem of a pulsed current sheet radiating into a DNG medium, it is shown that causality is maintained in t…
The transformation of nanodiamonds into carbon onions, and vice versa, has lead to the introduction of a new intermediate phase of carbon, coined ``bucky diamond,'' with a diamond core encased in an onion-like shell. Using a model based on the atomic heat of formation to describe the phase stability of carbon nanopart…
Synchrotron-based time-resolved x-ray diffraction (TR-XRD), x-ray absorption near edge spectroscopy (XANES), Raman spectroscopy (RS), and first-principles density functional (DF) calculations were used to study the structural and electronic properties of Ce–Ca mixed-metal oxides. The XRD results and DF calculations sh…
The magnetic and electronic structure of strontium hexaferrite SrFe 12 O 19 has been investigated using density functional theory within the local spin density approximation. The calculations show that in this ferrite all the Fe 3+ ions are fully spin polarized with S = 5/2. The electronic structure of this ferrite is…