Temperature waves in a horizontal liquid layer cooled from above

Waves in a thermal boundary layer were obtained by numerically modeling the natural thermogravitational convection in the infinite horizontal layer of a liquid cooled from above. The waves are generated via a mechanism related to the loss of stability and periodic separation of the upper, heavier and cooler liquid layer (penetrative convection).     

Surface barrier diode based on zinc selenide with a passivating zinc oxide film

We propose a method of fabricating surface barrier diodes with overlapped metal junction, which provides for a significant decrease in the reverse currents and an increase in the breakdown voltage.     

An analysis of nonlinear ion drift spectrometry for gas detectors with separating chamber of planar geometry

A consistent analytical model of nonlinear ion drift spectrometry for modern gas analyzers is developed. A procedure for determining the field dependence of the ion mobility using the experimental data is described. An ionogram is calculated for the case of a flat drift chamber and polynomial character of the field dependence of the ion mobility.     

Point Contact Spectroscopy and Temperature Dependence of Resistivity of Metallic Sodium Tungsten Bronzes - Role of Optical Phonons

In this paper we report the results of electrical resistivity (1.5≤ T ≤ 300K) and point contact spectroscopy (PCS) measurements on single crystals of metallic sodium tungsten bronze with varying sodium content. We have shown that the electron-phonon coupling function as measured through PCS can explain quantitatively the large temperature dependence of resistivity ρ seen in these materials over the entire temperature range. The electron-phonon coupling function shows predominately large peaks for phonon frequency range of 30 meV ≤ ω ≤ 100 meV which match well with the calculated optical phonons for WO₆ octahedron. The integrated electron-phonon coupling constant λ from this data is ≈ 0.25-0.45, depending on the Na content. PACS numbers: 72.15.-v, 72.80.Ga     

Atomistic simulations of the solubilization of single-walled carbon nanotubes in toluene

Solubilization of the armchair, metallic (10,10) single-walled carbon nanotubes (SWCNTs) in toluene is modeled using molecular dynamics simulations. Inter- and intra-molecular atomic interactions in the SWCNT + toluene system are represented using COMPASS (Condensed-phased Optimized Molecular Potential for Atomistic Simulation Studies), the first ab initio forcefield that enables an accurate and simultaneous prediction of various gas-phase and condensed-phase properties of organic and inorganic materials.The results obtained show that due to a significant drop in the configurational entropy of toluene, the solvation Gibbs free energy for these nanotubes in toluene is small but positive suggesting that a suspension of these nanotubes in toluene is not stable and that the nanotubes would fall out of the solution. This prediction is consistent with experimental observations.