Effect of Structure on Activation Parameters

355-35

Heat conduction of single-walled carbon nanotube isotope-superlattice structures: A molecular dynamics study

Heat conduction of single-walled carbon nanotubes (SWNTs) isotope-superlattice is investigated by means of classical molecular dynamics simulations. Superlattice structures were formed by alternately connecting SWNTs with different masses. On varying the superlattice period, the critical value with minimum effective thermal conductivity was identified, where dominant physics switches from zone-folding effect to thermal boundary resistance of lattice interface. The crossover mechanism is explained with the energy density spectra where zone-folding effects can be clearly observed. The results suggest that the critical superlattice period thickness depends on the mean free path distribution of diffusive-ballistic phonons. The reduction of the thermal conductivity with superlattice structures beats that of the one-dimensional alloy structure, though the minimum thermal conductivity is still slightly higher than the value obtained by two-dimensional random mixing of isotopes.Comment: 7 Pages, 5 figures, accepted to Phys. Rev.

Oxidation of Hydrazine, Phenylhydrazine & Substituted henylhydrazines by Thallium (III) - Substituent Effects & Mechanism

115-11

Significados múltiples y contradictorios del sobreendeudamiento : un estudio de caso de hogares en pobreza rural en Tamil Nadu

Con base en el estudio de caso de una zona rural en el sur de la India argumentamos que la definición de sobreendeudamiento no puede restringirse a procesos de empobrecimiento material, puesto que las consecuencias de la deuda en términos de estatus social —los prestatarios valoran y clasifican las deudas de acuerdo con pérdidas de autorrespeto y dignidad— son de gran relevancia. El significado social de la deuda es tan importante como sus criterios financieros, depende de relaciones preexistentes entre deudores y prestamistas, y a su vez fortalece, preserva y en ocasiones reta ciertas posiciones preexistentes dentro de las jerarquías locale

Oxidation of Glycine by Alkaline Hexacyanoferrate(III) - A Curious Dependence on Initial Concentration of the Oxidant

1112-111

A Stochastic Model for Crystal-amorphous Transition in Low Temperature Molecular Beam Epitaxial Si(111)

Molecular beam epitaxial Si (111) grown below a certain temperature result in amorphous structure due to the limited surface mobility of atoms in finding correct epitaxial sites. In spite of many experimental and theoretical studies, the mechanism of crystal‐amorphous transition and its dynamics related to the growth conditions are not well understood. In this article, we present a theoretical model based on the formation of stacking fault like defects as a precursor to the amorphous transition of the layer. The model is simulated based on a stochastic model approach and the results are compared to that of experiments for temperatures in the range of 500–900 K and growth rate in the range of 0.1–3.0 Å/s. The agreement between our results and experimental observations is excellent

Graded-bandgap AlGaAs solar cells for AlGaAs/Ge cascade cells

Some p/n graded-bandgap Al(x)Ga(1-x)As solar cells were fabricated and show AMO conversion efficiencies in excess of 15 percent without antireflection (AR) coatings. The emitters of these cells are graded between 0.008 is less than or equal to x is less than or equal to 0.02 during growth of 0.25 to 0.30 micron thick layers. The keys to achieving this performance were careful selection of organometallic sources and scrubbing oxygen and water vapor from the AsH3 source. Source selection and growth were optimized using time-resolved photoluminescence. Preliminary radiation-resistance measurements show AlGaAs cells degraded less than GaAs cells at high 1 MeV electron fluences, and AlGaAs cells grown on GaAs and Ge substrates degrade comparably