Magnetic properties of a new cobalt hydrogen vanadate with a dumortierite‐like structure: Co13.5(OH)6(H0.5VO3.5)2(VO4)6

The magnetic properties of a novel cobalt‐based hydrogen vanadate, Co_13.5(OH)₆(H_0.5VO_3.5)₂(VO₄)₆, are reported. This new magnetic material was synthesized in single‐crystal form using a conventional hydrothermal method. Its crystal structure was determined from single‐crystal X‐ray diffraction data and was also characterized by scanning electron microscopy. Its crystal framework has a dumortierite‐like structure consisting of large hexagonal and trigonal channels; the large hexagonal channels contain one‐dimensional chains of face‐sharing CoO₆ octahedra linked to the framework by rings of VO₄ tetrahedra, while the trigonal channels are occupied by chains of disordered V₂O₄ pyramidal groups. The magnetic properties of this material were investigated by DC magnetic measurements, which indicate the occurrence of antiferromagnetic interactions.     

On the performance of the algebraic optimized Schwarz methods with applications

We investigate the performance of algebraic optimized Schwarz methods used as preconditioners for the solution of discretized differential equations. These methods consist on modifying the so-called transmission blocks. The transmission blocks are replaced by new blocks in order to improve the convergence of the corresponding iterative algorithms. In the optimal case, convergence in two iterations can be achieved. We are also interested in the behavior of the algebraic optimized Schwarz methods with respect to changes in the problems parameters. We focus on constructing preconditioners for different numerically challenging differential problems such as: Periodic and Torus problems; Meshfree problems; Three-dimensional problems. We present different numerical simulations corresponding to different type of problems in two- and three-dimensions.     

Adsorption and corrosion inhibition of mild steel in hydrochloric acid solution by verbena essential oil

The inhibitive action of verbena essential oil (VEO) on the corrosion of mild Steel in 1 M HCl solutions in the temperature range 298 to 328 K was measured by use of the weight-loss method, potentiodynamic polarization, and electrochemical impedance spectroscopy. Results showed that VEO inhibited corrosion of C38 steel in 1 M HCl solution and that inhibition efficiency increased with increasing concentration of inhibitor but decreased proportionally with temperature. Potentiodynamic polarization studies suggested VEO is a mixed-type inhibitor, with the anodic type predominating. Nyquist plots were depressed semicircles with their centre below the real axis. Adsorption of VEO by the C38 steel surface followed the Langmuir adsorption isotherm. Kinetic data for dissolution were investigated.