Materials Literature
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The stability of a quasicrystalline structure, recently obtained in a molecular-dynamics simulation of rapid cooling of a binary melt, is analyzed for binary hard-sphere mixtures within a density-functional approach. It is found that this quasicrystal is metastable relative to crystalline and fluid phases for diameter…
An advanced potentiometric pH transducer based on processible polyaniline (PCPAn) is reported on. Both glassy carbon and screen-printed carbon electrodes modified with PCPAn by dip-coating exhibited a fully reversible potentiometric response of approximately 90 mV/pH unit over the range from pH 3 to 9. Such a signific…
The effective elasticity of highly charged stiff polyelectrolytes is studied in the presence of counterions, with and without added salt. The rigid polymer conformations may become unstable due to an effective attraction induced by counterion density fluctuations. Instabilities at the longest, or intermediate length s…
The magnetophotoluminescence (MPL) behavior of a GaAs/Al(0.3)Ga(0.7)As single heterojunction has been investigated to 60T. We observed negatively charged singlet and triplet exciton states that are formed at high magnetic fields beyond the nu=1 quantum Hall state. The variation of the charged exciton binding energies…
Coulomb driven, magneto-optically induced electron and hole bound states from a series of heavily doped GaAs/Al(0.3)Ga(0.7)As single heterojunctions (SHJ) are revealed in high magnetic fields. At low magnetic fields (nu > 2), the photoluminescence spectra display Shubnikov de-Haas type oscillations associated with the…
Over 100 oligoporphyrin (porphyrin molecules fused to each other through rigid acene-type bridges) molecules have now been synthesized, their long rigid π-bonded structures making them very suitable as molecular wires while their synthetic flexibility offers the possibility of tailoring their structural and electronic…
The amount of hydrogen adsorbed in arrays of single-walled carbon nanotubes has been studied as a function of the geometry of the array. The tube lattice spacing has been varied to optimize hydrogen uptake. Two different lattice geometries have been examined, namely, the triangular lattice and the square lattice. None…
A sudden drop in mechanical friction, between an adsorbed nitrogen monolayer and a lead substrate, occurs when the lead passes through the superconducting transition temperature. We attribute this effect to a sudden drop at the superconducting transition temperature of the substrate Ohmic heating. The Ohmic heating is…
Using a generalization of the Poisson-Boltzmann equation, dynamics of counterion condensation is studied. For a single charged plate in the presence of counterions, it is shown that the approach to equilibrium is diffusive. In the far from equilibrium case of a moving charged plate, a dynamical counterion condensation…
By means of molecular dynamics computer simulations we investigate the out of equilibrium relaxation dynamics of a simple glass former, a binary Lennard-Jones system, after a quench to low temperatures. We study both one time quantities and two-times correlation functions. Two-times correlation functions show a strong…
The experimentally predicted narrowing in the bandwidth of sodium is interpreted in terms of the non-local self-energy effect on quasi-particle energies of the electron liquid. The calculated self-energy correction is a monotonically increasing function of the wavenumber variable. The usual analysis of photo-emission…
Using molecular dynamics (MD) simulation, we investigate the mechanical response of silicon to high dose ion-irradiation. We employ a realistic and efficient model to directly simulate ion beam induced amorphization. Structural properties of the amorphized sample are compared with experimental data and results of othe…
As environmental performance becomes increasingly important, the development of man-made polymers and their associated benefits has been overshadowed by problems relating to their ultimate disposal. In the light of wider acceptance of polymers for use in high technology applications, Polymers and the Environment aims…
Spherical nanosize Ag/SiO 2 composite particles have been synthesized within reverse micelles via metal alkoxide hydrolysis and condensation. The size of the particles and the thickness of the coating can be controlled by manipulating the relative rates of the hydrolysis and condensation reactions of tetraethoxysilane…
The molecular, thermodynamic, and kinetic factors that govern the formation and concentration of the α and γ polymorphs in metallocene-catalyzed isotactic poly(propylenes) have been studied with a set of polymers that have a wide range in molecular weight and defect contents. With these polymers it was possible to inv…
The food packaging material is expected to provide optimum protective properties so that the product it encloses remains in satisfactory condition for its anticipated shelf life. The packaging tech...
The thermal stability of nanometer-sized Cu particles on a 400–500 nm thick SiO2 layer on top of a Si(100) substrate was studied after annealing in ultrahigh vacuum up to 620 °C. Atomic force microscopy, low-energy ion scattering, Rutherford backscattering spectrometry, and Auger electron spectroscopy measurements cle…
Low-resistivity (ρ) and highly transparent pure indium oxide (In2O3) thin films grown on glass substrates by pulsed laser deposition at substrate temperature (Ts) between room temperature and 200 °C are reported. As-deposited films with resistivity (ρ) of ∼3×10−4 Ω cm and transmittance (visible), above 87% were obtain…
Toroidal mesostructured molybdenum bronzes and blues (shown schematically) have been synthesized. The effect of phase changes on the electrical conductivity of these materials is explored in depth. A unique shape-evolution reaction is also discussed.
Das kristalline, spinlose π-Dimer (1.+⋅PF6)2 erhält man bei der Oxidation des Bipyrrols 1 mit Ferroceniumhexafluorophosphat. Die elektrochemisch in Lösung nachgewiesene diamagnetische Spezies wurde NMR-spektroskopisch als σ-Dimer identifiziert.