Materials Literature
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Solid oxide fuel cells that contain mixed ionic‐electronic conductors (MIECs) as electrolytes exhibit maximum efficiency at high ionic current density due to a small electronic leakage current. At low ionic current density the electronic current increases due to partial reduction of the electrolyte and efficiency decr…
The structural properties of ${\mathrm{Pr}}_{0.7}{\mathrm{Ca}}_{0.3}{\mathrm{MnO}}_{3}$ were studied by x-ray synchrotron and neutron-powder diffraction as a function of temperature $(15<T<300$ K), and as a function of x-ray fluence at 15 and 20 K. The temperature evolution of the lattice parameters and of the s…
Uniform spherical powders of Ce 0.9 Gd 0.1 O 1.95 with an average diameter of 250 nm were obtained at 700°C from a sol‐gel process of mixing nitrates and ethylene glycol. Broadening of the X‐ray peaks of the fluorite structure reveals a small crystallite size within the powders. Sintering in air of pressed pellets of…
Guymont's (Phys. Rev. B (1981), 24, 2647) nondisruption condition is made the basis for dividing phase transitions in crystals into nondisruptive and disruptive categories. Ferroic phase transitions are defined as nondisruptive phase transitions involving a change of point-group symmetry. Prototype symmetry is also de…
We have studied the thermodynamics of isolated homopolymer chains of varying stiffness using a lattice model. A complex phase behaviour is found; phases include chain-folded “crystalline” structures, the disordered globule and the coil. It is found, in agreement with recent theoretical calculations, that the temperatu…
Precise X-ray and high-energy transmission electron diffraction methods were used for the study of electron density and electrostatic potential in MgO crystals. The structure amplitudes were determined and their accuracy estimated using ab initio Hartree–Fock structure amplitudes as criteria. The electrostatic potenti…
Elastic moduli and refractive index of diamond, in the temperature range 300--1600 K, are determined using Brillouin scattering. The elastic moduli decrease by only $\ensuremath{\approx}8%$ up to 1600 K, indicating that diamond retains its reputed hardness even at high temperatures. We review the most commonly employe…
Abstract The reactive extrusion of polylactide (PLA) with a free radical initiator resulting in a branched polymer was accomplished. Reaction conditions were in the range of 160°C to 200°C with an initiator concentration between 0.0 and 0.5%. Triple detector size exclusion chromatography, melt flow index, thermal grav…
An immunological analysis of an Escherichia coli strain unable to synthesize the main pyruvate formate-lyase enzyme Pfl revealed the existence of a weak, cross-reacting 85 kDa polypeptide that exhibited the characteristic oxygen-dependent fragmentation typical of a glycyl radical enzyme. Polypeptide fragmentation of t…
A first-principle continuum-mechanics expression for the rolling friction coefficient is obtained for the rolling motion of a viscoelastic sphere on a hard plane. It relates the friction coefficient to the viscous and elastic constants of the sphere material. The relation obtained refers to the case when the deformati…
Abstract The electrospinning technique was used to spin ultra‐thin fibers from several polymer/solvent systems. The diameter of the electrospun fibers ranged from 16 nm to 2 μm. The morphology of these fibers was investigated with an atomic force microscope (AFM) and an optical microscope. Polyethylene oxide) (PEO) di…
We have performed static scattering experiments on the transition in time from a fluidlike sol to a solidlike gel of a suspension of disk-shaped charged colloidal particles. The combination of static light scattering and small angle x-ray scattering probes more than three orders of magnitude in the scattering vector $…
The coordination of carbon as a function of nitrogen concentration in energetically deposited carbon nitride films has been systematically studied. A structural transformation from primarily ${\mathrm{sp}}^{3}$-bonded to ${\mathrm{sp}}^{2}$-bonded carbon and a density decrease from 3.3 to $2.1 {\mathrm{g}/\mathrm{c}\m…
Complementation analysis of a polyhydroxyalkanoate (PHA)-negative mutant of Aeromonas caviae proved that ORF3 in the pha locus (a 402-bp gene located downstream of the PHA synthase gene) participates in PHA biosynthesis on alkanoic acids, and the ORF3 gene is here referred to as phaJ(Ac). Escherichia coli BL21(DE3) ca…
The martensitic transformation sequence in two single crystalline Ni-Mn-Ga alloys with a martensite start temperature ${(M}_{s})$ of about 400 K has been investigated using dynamic mechanical analysis, calorimetry, dilatometry, three-point bending tests, and transmission electron microscopy. A two-step thermally induc…
Nanosized hydrophobic, oleate stabilized silver organosols in various organic solvents are obtained using a solvent exchange method. The silver particles are initially prepared as a hydrosol in the presence of sodium oleate (surfactant). Then a transfer of the colloid to an organic phase is induced by a low concentrat…
We have measured and analyzed the Extended X-ray Absorption Fine Structure (EXAFS) of BaTiO3 at the barium k edge and the X-ray Absorption Near Edge Structure (XANES) at the titanium K edge. Our structural data show that the sequence of phase transitions in this material as the temperature increases is explained by a…
Self heating diminishes the reliability of silicon-on-insulator (SOI) transistors, particularly those that must withstand electrostatic discharge (ESD) pulses. This problem is alleviated by lateral thermal conduction in the silicon device layer, whose thermal conductivity is not known. The present work develops a tech…
We demonstrate that the tip of an atomic force microscope (AFM) can be used to control the shape and position of individual multiwalled carbon nanotubes dispersed on a surface. Specifically we can bend, straighten, translate, rotate, and under certain conditions cut nanotubes. Such manipulations are feasible due to th…
We report the effect of interfaces (and thus internal surface area effects) on the value of dielectric constant (K′) calculated from capacitance and geometry data for sub-micron barium titanate (BaTiO3) ceramics prepared with decreasing grain size (and grain volumes). A series model is proposed to explain the decreasi…