Cosmochemical, geochemical, and geophysical studies provide evidence that Earth's core contains iron with substantial (5 to 15%) amounts of nickel. The iron-nickel alloy Fe(0.9)Ni(0.1) has been studied in situ by means of angle-dispersive x-ray diffraction in internally heated diamond anvil cells (DACs), and its resistance has been measured as a function of pressure and temperature. At pressures above 225 gigapascals and temperatures over 3400 kelvin, Fe(0.9)Ni(0.1) adopts a body-centered cubic structure. Our experimental and theoretical results not only support the interpretation of shockwave data on pure iron as showing a solid-solid phase transition above about 200 gigapascals, but also suggest that iron alloys with geochemically reasonable compositions (that is, with substantial nickel, sulfur, or silicon content) adopt the bcc structure in Earth's inner core.
Identified cells of Helix lucorum L. received 20 min exposures to 23, 120, or 200 mT stationary magnetic field (MFs). Resting potentials and input resistances were measured. Controls were instituted for temperature changes and for mechanical and other sources of artifact. Resting potentials did not change with MF exposure. Input resistances decreased significantly in normally silent cells during MF exposure, but increased significantly in spontaneously active cells. The magnitudes of changes were monotonically related to strength of the MF. Changes in excitatory postsynaptic potentials were observed during MF exposure. Elimination of perineuronal glia by proteolytic enzymes eliminated the MF effects.
wurde durch Festko È rperreaktionen und Chemischen Transport nachgewiesen. Daru È ber hinaus wurden die Festko È rper-Gasphasengleichgewichte fu È r die Verbindungen massenspektrometrisch untersucht. Dabei wurde die Gasspezies BiSeCl erstmals experimentell nachgewiesen und ihre Geometrie und thermochemischen Eigenschaften u È ber ab-initio Moleku È lberechnungen charakterisiert. Weiterfu È hrende thermodynamische Modellierungen der heterogenen Gleichgewichte unterstu È tzen das Versta È ndnis der experimentellen Ergebnisse zur Gasphasenzusammensetzung sowie zum Chemischen Transport.Abstract. The existence of new compounds Bi 4 O 4 SeCl 2 , Bi 10 O 12 SeCl 4 , and Bi 22 O 28 SeCl 8 in the pseudoternary area Bi 2 O 3 /Bi 2 Se 3 /BiCl 3 has been established by solid state and chemical vapour transport reactions. Furthermore, heterogeneous equilibria between solid state and vapour phase have been studied by mass-spectrometric measurements. The novel gas-molecule BiSeCl has been detected. The results of ab initio calculations for structure and refining of thermochemistry of this molecule are given: (Bi±Se) = 2,44 A Ê ; (Bi±Cl) = 2,49 A Ê ; (Se±Bi±Cl) = 106,0°; Thermodynamics: DH°B ,298 (BiSeCl g ) = 6,0 kcal/mol; S°2 98 (BiSeCl g ) = 75,8 cal/mol K; Cp (BiSeCl g ) = 13,583 + 0,64´10 ±3´T ± 0,41´10 5´T±2 ± 0,351 0 ±6´T2 cal/mol K. Finally, the composition of the gaseous phase has been calculated and estimations about chemical vapour transport were carried out by thermodynamic modelling.
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