Macroscopic Geo-Magnetic Radiation Model; Polarization effects and finite volume calculations

An ultra-high-energy cosmic ray (UHECR) colliding with the Earth's atmosphere gives rise to an Extensive Air Shower (EAS). Due to different charge separation mechanisms within the thin shower front coherent electromagnetic radiation will be emitted within the radio frequency range. A small deviation of the index of refraction from unity will give rise to Cherenkov radiation up to distances of 100 meters from the shower core and therefore has to be included in a complete description of the radio emission from an EAS. Interference between the different radiation mechanisms, in combination with different polarization behavior will reflect in a lateral distribution function (LDF) depending on the orientation of the observer and a non-trivial fall-off of the radio signal as function of distance to the shower core.Comment: Proceedings of the ARENA2010 conference, Nantes, Franc

Hybrid tantalum oxide nanoparticles from the hydrolysis of imidazolium tantalate ionic liquids: efficient catalysts for hydrogen generation from ethanol/water solutions

The reaction of equimolar amounts of 1-n-butyl-3-methylimidazolium chloride (BMI·Cl) or 1-n-decyl-3-methylimidazolium chloride (DMI·Cl) with TaCl5 affords imidazolium tantalate ionic liquids (ILs) BMI·TaCl61 and DMI·TaCl62. The hydrolysis of ILs 1 and 2 yields hybrid-like tantalum oxide nanoparticles (NPs) with size distribution dependent on the nature of the IL used (3.8–22 nm from IL 1 and 1.5–6 nm from 2). A significant aggregation/agglomeration of the particles was observed after the removal of the IL content of the hybrid material by calcination, forming predominantly large particles (mainly bulk tantalum oxides). These new hybrid-like Ta2O5/IL NPs are highly active photocatalyst nanomaterials for hydrogen production by reforming of ethanol at ambient temperature. Hydrogen evolution rates up to 7.2 mmol H2 g−1 h−1 and high apparent quantum yields up to 17% were measured. The hybrid-like Ta2O5/IL NPs sputtered-decorated with ultra-small Pt NPs (1.0 ± 0.3 nm) as co-catalysts reached activities leading to even higher hydrogen production (9.2 H2 mmol g−1 h−1; apparent quantum yield of 22%). The calcined materials (with or without Pt NPs) showed much lower photocatalytic activity under the same reaction conditions (up to 2.8 mmol g−1 of H2). The remarkable activity of the hybrid-like Ta2O5/IL NPs may be related to the presence of the remaining IL that provides hydrophilic regions, facilitating the approach of polar molecules (water and alcohol) to the semiconductor active photocatalytic sites

The Spin Structure of the Nucleon

We present an overview of recent experimental and theoretical advances in our understanding of the spin structure of protons and neutrons.Comment: 84 pages, 29 figure

Bimetallic RuPd nanoparticles in ionic liquids: selective catalysts for the hydrogenation of aromatic compounds

Bimetallic RuPd nanoparticles (NPs) immobilized in ionic liquids (ILs) were shown to be a highly active medium for the selective hydrogenation of benzene and phenol under mild conditions (4 bar H-2, 60 degrees C) in a biphasic system (n-heptane/IL). The equimolar combination of Ru and Pd into a bimetallic particle generated a synergistic catalyst that allowed the selective production of cyclohexane (>99% selectivity, 94% conversion) and cyclohexanol (99% selectivity, >98% conversion) from the reduction of benzene and phenol, respectively. Moreover, the catalytic results revealed that the activity and selectivity are dependent on the Ru : Pd ratio into the bimetallic NPs