Peak effect at microwave frequencies in swift heavy ion irradiated YBa2Cu3O7-δ thin films

The vortex dynamics at microwave frequencies in YBa₂Cu₃O_7-δ (YBCO) films have been studied. We observe a peak in the microwave (4.88 and 9.55 GHz) surface resistance in some films in magnetic fields up to 0.8 T. This is associated with the ‘peak-effect’ phenomenon and reflects the order-disorder transformation of the flux line lattice near the transition temperature. Introduction of artificial pinning centers like columnar defects created as a result of irradiation with 200 MeV Ag ion (at a fluence of 4×10¹⁰ ions/cm²) leads to the suppression of the peak in films previously exhibiting ‘peak effect’.     

Steps as adatom sources for surface chemistry: oxygen overlayer formation on Ag(110)

Surface chemical reactions often require a ready supply of substrate atoms to occur. In principle, steps serve as an efficient source of these atoms, provided that detachment rates from the step edges are sufficiently large. In this paper, we characterize atomic detachment rates from steps on clean Ag(110) by examining step fluctuations. We show that these rates are sufficient to supply atoms to form the added-row reconstruction of oxidized Ag(110) when the oxygen partial pressure is low. For high oxygen pressures, however, we find that step detachment rates are slow compared with oxidation rates, and the step source of Ag is supplemented by vacancy-island generation on the terraces. These results are compared to those obtained for the similar O/Cu(110) and O/Ni(110) systems.     

Pre-concentration efficiency of chelex-100 resin for heavy metals in seawater : Part 1. Effects of pH and Salts on the Distribution Ratios of Heavy Metals

The chelating characteristics of Chelex-100 resin were studied for selected heavy metals in seawater medium. The results of batch equilibrium and breakthrough experiments show that the metal-chelating efficiency of the resin is lower in seawater than in freshwater. These differences are caused by the complicated speciation of heavy metals in seawater medium and by the high concentrations of magnesium and calcium present which act as competitors to heavy metal ions. The optimal pH values for column operation are strongly affected by the salt matrix. Careful choice of experimental conditions is necessary to avoid losses of cadmium and manganese from seawater. For better performance, seawater samples should be adjusted to pH 6–7 before loading onto a Chelex-100 column.     

Capillary Columns with a Sorbent Based on Functionalized Poly(1-Trimethylsilyl-1-Propyne) for the Elution Analysis of Natural Gas

Russian Journal of Physical Chemistry A - The chromatographic properties of capillary columns prepared using functionalized poly(1- trimethylsilyl-1-propyne) (PTMSP) are evaluated and compared with...