Magnetoresistance characteristics of Fe3Si/CaF2/Fe3Si heterostructures grown on Si(111) by molecular beam epitaxy

AbstractFe3Si/CaF2/Fe3Si magnetic tunnel junctions (MTJs) have been investigated to demonstrate the tunnel magnetoresistance effects. We fabricated Fe3Si(20 nm)/CaF2(2 nm)/Fe3Si(15 nm) heterostructures epitaxially on a Si(111) substrate by molecular beam epitaxy. The current-voltage characteristics for the MTJs measured at room temperature (RT) were well fitted to Simmons’ equation. The fitting yields the barrier height φ=2.5 eV and the barrier thickness d=1.26 nm. The magnetoresistance ratio for the MTJs were approximately 0.28% under a bias voltage of 20 mV at RT

An efficient synthesis of procyanidins. Rare earth metal Lewis acid catalyzed equimolar condensation of catechin and epicatechin

ArticleTETRAHEDRON LETTERS. 48(33): 5891-5894 (2007)journal articl

A Monte Carlo simulation of ion transport at finite temperatures

We have developed a Monte Carlo simulation for ion transport in hot background gases, which is an alternative way of solving the corresponding Boltzmann equation that determines the distribution function of ions. We consider the limit of low ion densities when the distribution function of the background gas remains unchanged due to collision with ions. A special attention has been paid to properly treat the thermal motion of the host gas particles and their influence on ions, which is very important at low electric fields, when the mean ion energy is comparable to the thermal energy of the host gas. We found the conditional probability distribution of gas velocities that correspond to an ion of specific velocity which collides with a gas particle. Also, we have derived exact analytical formulas for piecewise calculation of the collision frequency integrals. We address the cases when the background gas is monocomponent and when it is a mixture of different gases. The developed techniques described here are required for Monte Carlo simulations of ion transport and for hybrid models of non-equilibrium plasmas. The range of energies where it is necessary to apply the technique has been defined. The results we obtained are in excellent agreement with the existing ones obtained by complementary methods. Having verified our algorithm, we were able to produce calculations for Ar$^+$ ions in Ar and propose them as a new benchmark for thermal effects. The developed method is widely applicable for solving the Boltzmann equation that appears in many different contexts in physics.Comment: 14 page

Leistungsfähigkeit von Rettungsgeräten der Feuerwehr bei der Rettung von Personen aus Obergeschossen baulicher Anlagen

Zur Ermittlung der „Leistungsfähigkeit von Rettungsgeräten der Feuerwehr bei der Rettung von Personen aus Obergeschossen baulicher Anlagen“ sollte ein Fragebogen erarbeitet und an 100 Feuerwehren ver-schickt werden. Aufgrund unklarer Formulierungen der Fragen waren auch die Antworten nicht eindeutig und somit konnte die Auswertung der ausgefüllten Fragebögen keine nutzbaren Erkenntnisse bringen. Um dennoch verwertbare Erkenntnisse zu gewinnen, wurden Versuchsreihen mit verschiedenen Feuerweh-ren durchgeführt, bei denen die Rettungszeiten adipöser Personen, mittels Krankentrage auf die Drehleiter, untersucht wurden

Biological responses to change in Antarctic sea ice habitats

Sea ice is a key habitat in the high latitude Southern Ocean and is predicted to change in its extent, thickness and duration in coming decades. The sea-ice cover is instrumental in mediating ocean–atmosphere exchanges and provides an important substrate for organisms from microbes and algae to predators. Antarctic krill, Euphausia superba, is reliant on sea ice during key phases of its life cycle, particularly during the larval stages, for food and refuge from their predators, while other small grazers, including copepods and amphipods, either live in the brine channel system or find food and shelter at the ice-water interface and in gaps between rafted ice blocks. Fish, such as the Antarctic silverfish Pleuragramma antarcticum, use platelet ice (loosely-formed frazil crystals) as an essential hatching and nursery ground. In this paper, we apply the framework of the Marine Ecosystem Assessment for the Southern Ocean (MEASO) to review current knowledge about relationships between sea ice and associated primary production and secondary consumers, their status and the drivers of sea-ice change in this ocean. We then use qualitative network modelling to explore possible responses of lower trophic level sea-ice biota to different perturbations, including warming air and ocean temperatures, increased storminess and reduced annual sea-ice duration. This modelling shows that pelagic algae, copepods, krill and fish are likely to decrease in response to warming temperatures and reduced sea-ice duration, while salp populations will likely increase under conditions of reduced sea-ice duration and increased number of days of >0°C. Differences in responses to these pressures between the five MEASO sectors were also explored. Greater impacts of environmental pressures on ice-related biota occurring presently were found for the West and East Pacific sectors (notably the Ross Sea and western Antarctic Peninsula), with likely flow-on effects to the wider ecosystem. All sectors are expected to be impacted over coming decades. Finally, we highlight priorities for future sea ice biological research to address knowledge gaps in this field