Pressure effect on the in-plane magnetic penetration depth in YBa_2Cu_4O_8

We report a study of the pressure effect (PE) on the in-plane magnetic field penetration depth lambda_{ab} in YBa_2Cu_4O_8 by means of Meissner fraction measurements. A pronounced PE on lambda_{ab}^{-2}(0) was observed with a maximum relative shift of \Delta\lambda^{-2}_{ab}/\lambda^{-2}_{ab}= 44(3)% at a pressure of 10.2 kbar. It arises from the pressure dependence of the effective in-plane charge carrier mass and pressure induced charge carrier transfer from the CuO chains to the superconducting CuO_2 planes. The present results imply that the charge carriers in YBa_2Cu_4O_8 are coupled to the lattice.Comment: 4pages 3 figure

Depression of glutamate and GABA release by presynaptic GABAB receptors in the entorhinal cortex in normal and chronically epileptic rats

Presynaptic GABAB receptors (GABABR) control glutamate and GABA release at many synapses in the nervous system. In the present study we used whole-cell patch-clamp recordings of spontaneous excitatory and inhibitory synaptic currents in the presence of TTX to monitor glutamate and GABA release from synapses in layer II and V of the rat entorhinal cortex (EC)in vitro. In both layers the release of both transmitters was reduced by application of GABABR agonists. Quantitatively, the depression of GABA release in layer II and layer V, and of glutamate release in layer V was similar, but glutamate release in layer II was depressed to a greater extent. The data suggest that the same GABABR may be present on both GABA and glutamate terminals in the EC, but that the heteroreceptor may show a greater level of expression in layer II. Studies with GABABR antagonists suggested that neither the auto- nor the heteroreceptor was consistently tonically activated by ambient GABA in the presence of TTX. Studies in EC slices from rats made chronically epileptic using a pilocarpine model of temporal lobe epilepsy revealed a reduced effectiveness of both auto- and heteroreceptor function in both layers. This could suggest that enhanced glutamate and GABA release in the EC may be associated with the development of the epileptic condition. Copyright © 2006 S. Karger AG

Food Policy Development in the Australian State of Victoria: A Case Study of the Food Alliance

This article explores the development of a food policy body called the Food Alliance and the role of the organization in encouraging the development of food policy that integrates health and ecological issues. The Food Alliance is located within the Australian state of Victoria. A policy triangle is used as a framework to describe and analyse the work of the Food Alliance. Lessons are drawn about effective strategies for influencing integrated food policy. This occurs in a context where food policy typically favours powerful industry and agricultural interests and where relationships between the health and environmental sectors are in their infancy. The implications for planning and organizing a state-wide food policy are explored from the perspective of policy and the ways in which this can be influenced through working with key stakeholders

Pressure effect on magnetism and multiferroicity in Mn2GeO4

The effect of high pressure exceeding 6 GPa on magnetism and multiferroicity was investigated for the olivine Mn2GeO4 that shows successive magnetic transitions at ambient pressure and a ferroelectric ground state driven by spin- spiral order. We measured heat capacity, dielectric constant, and electric polarization at various pressures using a diamond anvil cell. The pressure evolution of the magnetic structures was also investigated by powder neutron diffraction measurements using a Paris- Edinburgh press. We found that all of the magnetic transition temperatures are enhanced monotonically by applying pressure. Furthermore, the spin- driven ferroelectricity persists up to about 6 GPa but suddenly vanishes by 6.3 GPa. A consistent description of all data is achieved if an incommensurate- commensurate phase transition occurs with pressurization and causes the suppression of ferroelectricity. We discuss the origin of the observed pressure effects on the magnetism and multiferroicity in Mn2GeO4 in terms of a pressure- induced change in the superexchange magnetic interactions

A thermally self-sustained micro-power plant with integrated micro-solid oxide fuel cells, micro-reformer and functional micro-fluidic carrier

Low temperature micro-solid oxide fuel cell (micro-SOFC) systems are an attractive alternative power source for small-size portable electronic devices due to their high energy efficiency and density. Here, we report on a thermally self-sustainable reformer micro-SOFC assembly. The device consists of a micro-reformer bonded to a silicon chip containing 30 micro-SOFC membranes and a functional glass carrier with gas channels and screen-printed heaters for start-up. Thermal independence of the device from the externally powered heater is achieved by exothermic reforming reactions above 470 °C. The reforming reaction and the fuel gas flow rate of the n-butane/air gas mixture controls the operation temperature and gas composition on the micro-SOFC membrane. In the temperature range between 505 °C and 570 °C, the gas composition after the micro-reformer consists of 12 vol.% to 28 vol.% H2. An open-circuit voltage of 1.0 V and maximum power density of 47 mW cm−2 at 565 °C is achieved with the on-chip produced hydrogen at the micro-SOFC membranes

A thermally self-sustained micro-power plant with integrated micro-solid oxide fuel cells, micro-reformer and functional micro-fluidic carrier

Low temperature micro-solid oxide fuel cell (micro-SOFC) systems are an attractive alternative power source for small-size portable electronic devices due to their high energy efficiency and density. Here, we report on a thermally self-sustainable reformer micro-SOFC assembly. The device consists of a micro-reformer bonded to a silicon chip containing 30 micro-SOFC membranes and a functional glass carrier with gas channels and screen-printed heaters for start-up. Thermal independence of the device from the externally powered heater is achieved by exothermic reforming reactions above 470 °C. The reforming reaction and the fuel gas flow rate of the n-butane/air gas mixture controls the operation temperature and gas composition on the micro-SOFC membrane. In the temperature range between 505 °C and 570 °C, the gas composition after the micro-reformer consists of 12 vol.% to 28 vol.% H2. An open-circuit voltage of 1.0 V and maximum power density of 47 mW cm−2 at 565 °C is achieved with the on-chip produced hydrogen at the micro-SOFC membranes