Exterior Differentials in Superspace and Poisson Brackets

It is shown that two definitions for an exterior differential in superspace, giving the same exterior calculus, yet lead to different results when applied to the Poisson bracket. A prescription for the transition with the help of these exterior differentials from the given Poisson bracket of definite Grassmann parity to another bracket is introduced. It is also indicated that the resulting bracket leads to generalization of the Schouten-Nijenhuis bracket for the cases of superspace and brackets of diverse Grassmann parities. It is shown that in the case of the Grassmann-odd exterior differential the resulting bracket is the bracket given on exterior forms. The above-mentioned transition with the use of the odd exterior differential applied to the linear even/odd Poisson brackets, that correspond to semi-simple Lie groups, results, respectively, in also linear odd/even brackets which are naturally connected with the Lie superalgebra. The latter contains the BRST and anti-BRST charges and can be used for calculation of the BRST operator cohomology.Comment: 12 pages, LATEX 2e, JHEP format. Correction of misprints. The titles for some references are adde

Nambu-Poisson dynamics with some applications

Short introduction in NPD with several applications to (in)finite dimensional problems of mechanics, hydrodynamics, M-theory and quanputing is given.Comment: 11 page

Brackets, Sigma Models and Integrability of Generalized Complex Structures

It is shown how derived brackets naturally arise in sigma-models via Poisson- or antibracket, generalizing a recent observation by Alekseev and Strobl. On the way to a precise formulation of this relation, an explicit coordinate expression for the derived bracket is obtained. The generalized Nijenhuis tensor of generalized complex geometry is shown to coincide up to a de-Rham closed term with the derived bracket of the structure with itself, and a new coordinate expression for this tensor is presented. The insight is applied to two known two-dimensional sigma models in a background with generalized complex structure. Introductions to geometric brackets on the one hand and to generalized complex geometry on the other hand are given in the appendix.Comment: 48 pages (27 without appendix), created with LyX, based on LaTeX, including hyperrefs. Typos in (2.162)-(2.167) and in (3.15) fixed. Content agrees with JHEP-Version. Page numbers and equation numbers agree with old version but not with JHEP version

A direct borohydride – acid peroxide fuel cell

A fuel cell operating with aqueous sodium borohydride and hydrogen peroxide streams, with one, two and four cells (electrode area 64, 128 and 256 cm2) connected in a bipolar mode in a filterpress flow cell is reported. The oxidation of borohydride ion was carried out on Au/C particles supported on a carbon felt electrode while the reduction of hydrogen peroxide was carried out on carbon supported Pt on a carbon paper substrate. Comparable cell potentials and power densities to direct borohydride fuel cells reported in the literature were obtained. The challenges to further development includes: increasing the low current density and avoid decomposition of borohydride and peroxide ions. The maximum power obtained at 20oC for one, two and four cell stacks was 2.2, 3.2 and 9.6 W (34.4, 25 and 37.5 mW cm-2 respectively) with cell voltages of 1.06, 0.81 and 3.2 V at current densities of 32, 16 and 12 mA cm-2, respectively

Characterization of the reaction environment in a filter-press redox flow reactor

The characteristics of a divided, industrial scale electrochemical reactor with five bipolar electrodes (each having a projected area of 0.72 m2) were examined in terms of mass transport, pressure drop and flow dispersion. Global mass transport data were obtained by monitoring the (first order) concentration decay of dissolved bromine (which was generated in situ by constant current electrolysis of a 1 mol dm?3 NaBr(aq)). The global mass transport properties have been compared with those reported in the literature for other electrochemical reactors. The pressure drop over the reactor was calculated as a function of the mean electrolyte flow velocity and flow dispersion experiments showed the existence of slow and fast phases, two-phase flow being observed at lower velocities