Geometrical surface vortex pinning in superconducting films

A model is proposed for vortex pinning in a superconducting film with a rough surface. The model relates the critical current to the steepness of the surface relief and, at a high vortex concentration, to the distance between neighboring steepness maxima on the paths of vortex motion. The dependence of the critical current density on the thickness of a high-T_c superconducting film is measured in a weak magnetic field. Its behavior can be explained by the pinning at the stepped surface relief.     

Relativistic treatment of the hard-bremsstrahlung process <Emphasis Type="Italic">pp</Emphasis> → <Emphasis Type="Italic">ppγ</Emphasis> and possibility of discriminating between different types of nucleon-nucleon interaction

Previous results of the present authors, who showed that observables of the hard-bremsstrahlung process pp → ppγ at beam energies ranging between 350 and 500 MeV are highly sensitive to the type of nucleon-nucleon potential (meson-exchange potentials versus the Moscow potential), are generalized by means of a relativistic analysis, which includes, above all, a modified current operator. As a result, the relevant cross sections decrease, while their angular dependence changes. However, the above high sensitivity to the type of potential survives and becomes quite significant even at the lowest beam energy of 280 MeV considered here, for which there are experimental data. They seem to favor one of the versions of the Moscow potential.     

Functionalization of chloromethylphosphoryl compounds with sulfur in the presence of amines

Russian Chemical Bulletin -     

An YBCO film as a Josephson medium near T c : Frequency and field dependences and scaling relationships

The diamagnetic response of a laser-deposited YBCO film was studied in weak exciting magnetic fields H _ac =H ₀sinωt (H ₀=2–500 mOe, ω/2π=1–30 kHz). An analysis of the experimentally measured diamagnetic response showed evidence of a ring character of the electric field flowing in the sample at small H ₀ values. The plots of T _m (the temperature of maximum dissipative losses χ″₁) versus H ₀ measured at various frequencies showed the existence of a certain critical field strength H*(ω) at which the (1?T _m /T _c ) versus H ₀ ^2/3 plots exhibit a break. A logarithmic dependence of T _m on the frequency ω of the exciting field H _ac is reliably valid only in the region of (ω/2π)>5 kHz. Verification of the scaling relationship showed that this relationship is valid (to within the experimental accuracy) for the frequencies ω above 5 kHz and the field amplitudes H ₀>H*(ω). However, the exponent n in the scaling relationship under consideration is not correlated with the exponent n in the power relationship describing the current-voltage characteristic.     

Growth of InN films and nanorods by H-MOVPE

InN films and nanorods were grown by hydride metalorganic vapor phase epitaxy (H-MOVPE) and the effects of growth temperature, and NH₃/TMIn and HCl/TMIn ratios on morphological dependences were studied. The growth habit of InN varied from thin film to microrod to nanorod to no deposition as the growth conditions were changed about transition from growth to etching conditions. The growth and etch regimes were also predicted by chemical equilibrium calculations of In–C–H–Cl–N-inert system. The optical properties of InN nanorods and columnar structured films were measured by room temperature PL and a maximum intensity was observed at 1.08 eV for both structures.     

Effect of ionogenic groups on the collapse of thermosensitive gels

The effect of the different kinds of ionogenic groups of copolymers of N-isopropylacrylamide with sodium methacrylate, sodium vinylsulfonate, and diallyldimethylammonium chloride on the temperature-induced conformation transition from a swollen gel to a collapsed gel is studied. The presence of different kinds of ionogenic groups in a thermosensitive copolymer is shown to affect the temperature, collapse amplitude, and reversibility of the transition between the swollen gel and the collapsed gel.