Problem with nonequilibrium boundary conditions in the kinetic theory of gases

The Boltzmann kinetic equation is considered in a new formulation with nonequilibrium distribution functions on free boundaries, which makes it possible to simulate nonequilibrium superand subsonic flows. Transport processes for such flows are analyzed. The possibility of anomalous transport is determined, in which case the heat flux, temperature gradient, and the corresponding components of the nonequilibrium stress tensor and the velocity gradient have the same sign.     

Discussion on a possible neutrino detector located in India

We have identified some important and worthwhile physics opportunities with a possible neutrino detector located in India. Particular emphasis is placed on the geographical advantage with a stress on the complimentary aspects with respect to other neutrino detectors already in operation.     

High spin spectroscopy of 139Pr

The high spin states in N=80 ¹³⁹Pr have been investigated by in-beam γ-spectroscopic techniques following the reaction ¹³⁰Te (¹⁴N, 5n) reaction at E=75 MeV, using a gamma detector array, consisting of seven 23% compton-suppressed high purity germanium detectors and a multiplicity ball of fourteen bismuth germanate elements. Based on γ-γ coincidence data, the level scheme of ¹³⁹Pr has been considerably extended up to 7.2 MeV excitation. Tentative spin-parity assignments are done for the newly proposed levels on the basis of the DCO ratios corresponding to strong gates and the available information from the earlier light ion experiments.     

有机磷化合物的研究XIX.III亚磷酸二烷基酯钠的相转移催化P-烷基化反应

Sodium dialkyl phosphite reacts with non-activated alkyl halide in the presence of crown ether to give dialkyl alkyl phosphonate in moderate yield. Little or no reaction takes place in the absence of crown ether under the same conditions. In all cases, crown ether was present in catalytic amts. indicating that it behaves as a phase transfer catalyst between solid and liquid phases. The influences of structures of crown ethers, alkyl halides, dialkyl phosphites and the nature of solvent on the P-alkylation of sodium dialkyl phosphite have been investigated.     

Measurements of the diffusion coefficient of nanoparticles by selective plane illumination microscopy

A laser-based selective plane illumination microscope is developed for the visualization of polystyrene nanospheres about 100 nm in diameter in water at a distance more than 600 μm from microcell walls. The contrast and brightness of particle images are high enough to record them by a video camera with a frame rate of up to 60 frames per second without using an image intensifier. The diffusion coefficients of monodisperse polystyrene nanospheres obtained using this microscope and the image processing software developed by the authors are presented. The measured diffusion coefficients provide the possibility to determine nanosphere diameters with a relative error not exceeding 5%.     

Mesoscale hydrodynamics simulations of particle suspensions under shear flow: From hard to ultrasoft colloids

We discuss the nonequilibrium properties of rodlike and ultrasoft, star-polymer like colloidal particles in shear flow. Conformational, dynamical, as well as rheological aspects are addressed for a broad range of concentrations. For concentrated solutions of rodlike colloids, we study the nonequilibrium properties of a phase separated system, where a disordered phase coexists with a nematic phase. For starlike polymers we consider systems of various functionality, starting from linear polymers. The individual rods, polymers, or stars exhibit an intriguing dynamical behavior, which determines their macroscopic rheological properties. Despite the diversity on the colloidal level, the various systems exhibit a qualitatively similar macroscopic behavior, e.g., shear thinning, yet with some quantitative differences.     

Fluctuation conductivity in cuprate superconductors

We have measured the in-plane resistivity of Bi₂Sr₂CaCu₂O_8+δ and Tl₂Ba₂ CaCu₂O_8+δ single crystals in the temperature range 70–300 K. The thermodynamic fluctuations in the conductivity of both the samples start around ∼ 125 K. We find the Lawrence and Doniach [1] model to be inadequate to describe the fluctuation conductivity in these materials. The modification suggested by Ramallo et al [4] where by the conductivity is enhanced due to the presence of two superconducting layers in each unit cell is also not adequate. We suggest the fluctuation conductivity to be reduced due to the reduction in the density of states (DOS) of the quasiparticles which results due to the formation of Cooper pairs at the onset of the fluctuations. The data agrees with the theory proposed by Dorin et al [5] which takes into account this reduction in DOS.     

Hysteresis and negative differential resistance of the I–V characteristic of a water bridge

It is experimentally demonstrated that the recently discussed properties of the nanopore ion-exchange membranes (hysteresis of the I–V characteristic in solution and negative differential resistance) are not related to the membrane structure. The same effects are observed in a water bridge and tubes filled with water and may be related to the geometrical shape of the liquid conductor. The experimental effects are qualitatively interpreted.