Magnetic field driven instability of charged center in graphene

It is shown that a magnetic field dramatically affects the problem of supercritical charge in graphene making any charge in gapless theory supercritical. The cases of radially symmetric potential well and Coulomb center in an homogeneous magnetic field are considered. The local density of states and polarization charge density are calculated in the first order of perturbation theory. It is argued that the magnetically induced instability of the supercritical Coulomb center can be considered as a quantum mechanical counterpart of the magnetic catalysis phenomenon in graphene.Comment: 10 pages, 4 figures; to be published in PR

Anatomy of a cluster IDP. Part 2: Noble gas abundances, trace element geochemistry, isotopic abundances, and trace organic chemistry of several fragments from L2008#5

The topics discussed include the following: noble gas content and release temperatures; trace element abundances; heating summary of cluster fragments; isotopic measurements; and trace organic chemistry

Light Element Isotopic Compositions of Cometary Matter Returned by the STARDUST Mission

Hydrogen, carbon, nitrogen, and oxygen isotopic compositions are heterogeneous among comet 81P/Wild2 particle fragments, however extreme isotopic anomalies are rare, indicating that the comet is not a pristine aggregate of presolar materials. Non-terrestrial nitrogen and neon isotope ratios suggest that indigenous organic matter and highly volatile materials were successfully collected. Except for a single circumstellar stardust grain, silicate and oxide minerals have oxygen isotopic compositions consistent with solar system origin. One refractory grain is {sup 16}O-enriched like refractory inclusions in meteorites, suggesting formation in the hot inner solar nebula and large-scale radial transport prior to comet accretion in the outer solar system

Solar Wind and Spallation Neon in Small Dark Fragments Separated from the Kapoeta Howardite: Evidence for Early GCR Irradiation?

The Kapoeta howardite contains abundant noble gases in the dark phases of its brecciated structure, implanted during exposure of the parent body regolith to the solar wind. These gases have been studied extensively over the years, most recently by the modern closed-system stepped etching technique, in efforts to determine the elemental and isotopic composition of the solar wind at the time of regolith exposure. Kapoeta is interesting as well for another aspect of its irradiation history: several investigations, most recently by Rao et al., have shown that the dark, solar-wind-irradiated phases contain excesses of spallation-produced Ne above the levels expected to be generated by galactic cosmic rays (GCR) during the meteorite\u27s space exposure age of ~3 Ma. These excesses have been attributed to production by GCR, and by a solar cosmic ray (SCR) flux substantially enhanced over current levels, during an early ~3-6 Ma irradiation of the parent-body regolith prior to compaction, burial, and ultimate ejection of the Kapoeta object to space

Helium and neon abundances and compositions in cometary matter

International audienc

Helium and Neon in a Stardust Track Wall

Materials trapped and preserved in comets date from the earliest history of the solar system. Here we present and discuss recent measurements of light noble gases carried in a particle captured from comet Wild2 by the Stardust mission

Arbeitssysteme in der grobkeramischen Industrie

Available from TIB Hannover: F95B193+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman