Electrochemistry of MoO3–K2MoO4 melts: a chance to control the nature of reduced molybdenum oxides

Cathodic electrodeposition of oxides on platinum from MoO₃–K₂MoO₄ (3.85–75?mol% MoO₃) under DC and pulsed galvanostatic modes is discussed in combination with voltammetry data. Characteristic potential values (as related to oxygen evolution onset) are reported for Mo(VI/IV) redox processes, as well as for electrochemical equilibria with participation of molybdenum metal and Pt–Mo alloys. On the basis of scan rate effects and results for various potential limits, and also of voltammetry with preliminary potentiostatic accumulation of products, molybdate reduction mechanism complicated by a chemical step of Mo metal oxidation is proposed. This qualitative assumption is verified in preparative electrolysis experiments with products identification by means of X-ray diffractometry, scanning electron microscopy, and EDX local analysis. Deposition under pulsed mode is found to be useful tool to adjust the duration of chemical step and by these means to alter the composition of final products. The conditions supporting the formation of MoO₂ and more reduced oxides are formulated.     

The spatial resolution of the CMS ME1/1 muon station cathode strip chambers with CRAFT08 data

The spatial resolution of the outer part of the ME1/1 muon station has been studied with CRAFT08 (Cosmic Rays At Four Tesla-2008) data at the CMS detector (CERN). The ME1/1 Cathode Strip Chamber (CSC) layer spatial resolution as a function of the CMS solenoid magnetic field is presented. The influence of the strip width and anode wire tilt on the spatial resolution has been studied. Finally, the spatial resolution for the ME1/1 6-layer CSC was calculated and the ME1/1 outer part spatial resolution was estimated.     

New Examples of Locally Algebraically Integrable Bodies

Mathematical Notes - Any compact body with regular boundary in ℝN defines a two-valued function on the space of affine hyperplanes: the volumes of the two parts into which these hyperplanes...     

Stratified Picard-Lefschetz theory

The monodromy action in the homology of level sets of Morse functions on stratified singular analytic varieties is studied. The local variation operators in both the standard and the intersection homology groups defined by the loops around the critical values of such functions are reduced to similar operators in the homology groups of the transversal slices of the corresponding strata.To Robert MacPhersonResearch supported by International Science Foundation (grant MQO 000).     

Non-resonant microwave absorption studies of superconducting MgB2 and MgB2 + MgO

Non-resonant microwave absorption (NRMA) studies of superconducting MgB₂ and a sample containing ∼10% by weight of MgO in MgB₂ are reported. The NRMA results indicate near absence of intergranular weak links in the pure MgB₂ sample. A linear temperature dependence of the lower critical field H _c1 is observed indicating a non-s wave superconductivity. However, the phase reversal of the NRMA signal which could suggest d wave symmetry is also not observed. In the MgB₂ + MgO sample, much larger low field dependent absorption is observed indicating the presence of intergranular weak links. The hysteretic behavior of NRMA is compared and contrasted in the two samples. In the pure MgB₂ sample, a large hysteresis is observed between the forward and the reverse scans of the magnetic field indicating strong pinning of flux lines. This hysteresis saturates a few degrees below T _c while in the MgB₂ + MgO sample, a much slower increase of hysteresis with decreasing temperature is observed, a signature of weaker pinning.     

On pseudolinearity and generic pairs

We continue the study of the connection between the “geometric” properties of SU ‐rank 1 structures and the properties of “generic” pairs of such structures, started in [8]. In particular, we show that the SU‐rank of the (complete) theory of generic pairs of models of an SU ‐rank 1 theory T can only take values 1 (if and only if T is trivial), 2 (if and only if T is linear) or ω, generalizing the corresponding results for a strongly minimal T in [3]. We also use pairs to derive the implication from pseudolinearity to linearity for ω ‐categorical SU ‐rank 1 structures, established in [7], from the conjecture that an ω ‐categorical supersimple theory has finite SU ‐rank, and find a condition on generic pairs, equivalent to pseudolinearity in the general case (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Electroreduction of carbon dioxide: Part III. Adsorption and reduction of CO2 on platinum

The main properties of reductional adsorption of CO₂ on the platinum metals are studied. Chemisorbed particles are found to be produced only on platinum and rhodium. Electroreduction of CO₂ on these metals proceeds as a result of the interaction of CO₂ molecules activated in the course of adsorption on the metal surface with chemisorbed hydrogen. As a result, strongly chemisorbed particles are obtained on the surface which are the products of more profound reduction of CO₂ than to formic acid. The further reduction of these chemisorbed particles, accompanied by their desorption into the solution, is very slow due to very strong coupling of sorbed particles with the surface and to very fast backward adsorption of the reduction products. Neither reductional chemisorption of CO₂ nor interactions of CO₂ with adsorbed hydrogen were observed for iridium, palladium, osmium or ruthenium.     

Subkilohertz enhanced-power diode-laser spectrometer in the visible

We report on a high-performance diode-laser spectrometer operating near 657 nm with narrow linewidth (<0.6kHz) , enhanced power (as much as 40 mW), and low drift (<10Hz/s) . The spectrometer comprised an extended-cavity diode-laser frequency stabilized to a high-finesse optical resonator and a broad-area antireflection coated laser diode as an amplifier with a single-lobe emission pattern of good spatial purity. The spectrometer was used to record time-domain optical Ramsey spectra of laser-cooled Ca atoms with a resolution of 0.6 kHz.