Three-dimensional localization of atoms in the polychromatic optical superlattice

Quasiclassical kinetic theory of the light pressure force has been applied to describe the localization of atoms (or ions) with the transition F=1→F=0 in the three-dimensional (3D) dissipative optical superlattice of a new type. Its action is based on the effect of the gradient force rectification in the polychromatic field: superposition of the three color far-off-resonant field and partially coherent resonant field. An approximate explicit solution of the kinetic equation for 3D motion of atoms in such a (multicolor) field has been achieved. This solution demonstrates the capability of the polychromatic superlattice to provide efficient cooling and strong spatial localization of the particles and to form an atomic (or ionic) grating with highly controllable characteristics.     

Estimation of zeta potentials of titania nanoparticles by molecular simulation

Non-equilibrium molecular dynamics (NEMD) simulations have been performed for static electric fields for a range of positively charged spherical rutile-titania nanoparticles with radii of 1.5 to 2.9 nm for two different salt concentrations in water, in order to simulate electrophoresis directly. Using the observed limiting drag velocities, Helmholtz-Smoluchowski (HS) theory was used to estimate their ζ potentials. These estimates were compared to values from numerical solution of the non-linear Poisson-Boltzmann (PB) equation for representative configurations of the nanoparticles, in addition to idealised analytic and Debye-Hückel (DH) solutions about spherical particles of the same geometry and charge state, for the given salt concentrations. It was found that reasonable agreement was obtained between the various approaches, with the NEMD-HS results some 15%-15% smaller than the numerical PB results for more highly charged nanoparticles.     

Revealing sol-gel type main effects by exploring a molecular cluster behavior in model in-plane amphiphilic aggregations

In-plane (bio)matter aggregations of amphiphilic nature are modeled extensively by Monte Carlo simulation in their natural entropic contexts. The modeling starts by designing the aggregations at a molecular level, pointing to its well-known configuration vs conformation character. Then, the conformational behavior is distributed over the aggregations obtained, with the aim of revealing their main sol-gel type (viscoelastic) effects. The passage between the resulting sol and gel phases is not controlled by a scan in the temperature domain, on the contrary, the control parameter is selected to be the hydrophobic-interaction strength while the temperature remains unchanged. The distribution of ordered fringed micelles, and the overall crystalline inclusions of the gel phase, suggested a first-order phase change, reasonably conceivable in terms of Avrami-Kolmogorov formalism for such hydrophobic-force driven and percolation-in-nature systems. A phase transition diagram has been presented as a novel proposition to discern between sol vs gel phases. As specific results, also of high experimental value, a damped-oscillating cluster-involving effect on the resulting hydrophobic-polar matrices has been detected and analysed. Other additional intermolecular-sharing entropy-influenced effects on clustering, as seen in terms of chain-to-chain connectivities, have been addressed as being of sufficient relevance to the gelation mechanism described. The microcrystalline inclusions downgrade to some extent the overall picture of entropy-affected gelation, being all together suitable for experimental check-out.     

Silver-doped calcium phosphate nanopowders prepared by electrostatic spraying

Silver-doped calcium phosphate nanopowders were successfully prepared by the cost-effective electrostatic spray-pyrolysis process. The properties of the silver-doped nanopowder annealed at 500°C for 30 min were investigated through X-ray diffraction analysis, field emission scanning electron microscope, and Fourier transform infrared spectroscopy. The silver-doped nanopowders with 70–90 nm particle size showed an antibacterial performance against Escherichia coli.     

变质量质点的动能定理与软绳问题

给出变量质点的动能定理和一对反推内力作功的表达式,并由此给出软绳问题的正确解。     

Anomalous non-coincidence effects in liquids: separation of attraction and repulsion contributions

A method enabling one to separate the contributions of repulsion and attraction forces resulting in frequency non-coincidences in liquids is presented.     

Pressure effects on 2p5 3p - 2p5 3d transitions in neon

The collisional broadening and shift of four spectral lines of neon (747.2, 748.8, 753.5, 754.4 nm) arising from 2p⁵ 3p - 2p⁵ 3d transitions, emitted from a low-pressure glow discharge in pure neon and neon-helium mixtures have been measured using a Fabry-Perot interferometer. The values of pressure broadening and shift coefficients are determined and analyzed in terms of the impact theory.     

Comparison of calorimetric and IR-spectroscopic data for alcohols and alcoholic solutions

The heats of solution of alcohols in hexane can be considered as the energy necessary to break hydrogen bonds (H-bond). The amount of non H-bonded OH groups estimated from caloric data, are in good agreement with IR-spectroscopic data. Comparison of calorimetric and IR-spectroscopically determined H-bond energies permit the separation of intermolecular van der Waals effects from H-bond interactions. This separation shows that van der Waals interactions of alcohols or water should not be underestimated.     

Excitation functions of the analyzing power in elastic proton-proton scattering from 0.45 to 2.5 GeV

Excitation functions A_N(p_lab,_c.m.) of the analyzing power in elastic proton-proton scattering have been measured in an internal target experiment at the Cooler Synchrotron COSY with an unpolarized proton beam and a polarized atomic hydrogen target. Data were taken continuously during the acceleration and deceleration for proton kinetic energies T_lab (momenta p_lab) between 0.45 and 2.5 GeV (1.0 and 3.3 GeV/c) and scattering angles 30 ^° _c.m. 90^°. The results provide excitation functions and angular distributions of high precision and internal consistency. The data can be used as calibration standard between 0.45 and 2.5 GeV. They have significant impact on phase shift solutions, in particular on the spin triplet phase shifts between 1.0 and 1.8 GeV.