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The synthesis of an 8-aza-PGE1 analog, (E)-7-[[2-[4-(m-trifluoromethylphenoxy)-3α and 3β-hydroxy-1-butenyl]-5-oxo-pyrrolidinyl]]heptanoic acids is reported. 相似文献
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Properties of Mn3XN and Mn3XC types of compounds are analyzed on the basis of a model for the electronic band structure, which consists of a large conduction band overlapping a narrow band that results from the strong hybridization between the p orbitals of the metalloid and some of the d orbitals of the manganese. The crystal field at the sites of manganese is assumed to be strong. The structure of the narrow band is calculated in the tight-binding model. The Fermi energy lies very close to a sharp singularity in the density of states. In the cubic and Pauli paramagnetic phase, such a singularity has a sixfold degeneracy. The magnetic and structural instabilities, which appear when the temperature is decreased, are explained by the removal of that degeneracy by a shear strain and the formation of small magnetic moments. The phase transitions can be studied in detail by expanding the variation of the free energy with respect to the shear strains and the magnetic moments. The coefficients of the expansion are calculated as functions of the temperature. The variation of the volume is explained by the existence of coupling terms to the shear strain and to the magnetic moments. 相似文献
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Volodymyr Babizhetskyy Volodymyr Levytskyi Régis Jardin Josef Bauer Roland Guérin Régis Gautier Bruno Fontaine Jean-François Halet 《无机化学与普通化学杂志》2020,646(14):1168-1175
Two novel ternary borosilicides R9Si15–xB3 (R = Tb, x = 1.80, R = Yb, x = 1.17) were synthesized from the initial elements using tin flux method. Their crystal structures were determined by means of X-ray single crystal diffraction. Both refer to space group R32, Z = 1: a = 6.668(2) Å, c = 12.405(4) Å [R1 = 0.027, wR2 = 0.031 for 1832 reflections with Io > 2σ (Io)] for Tb9Si15–xB3, and a = 6.5796(3) Å, c = 12.2599(5) Å [RF = 0.052, wR = 0.090 for 1369 reflections with Io > 2σ (Io)] for Yb9Si15–xB3. The structures represent a new structure type, derived from that of AlB2, with ordering in the metalloid sublattice resulting in distorted [Si5B] hexagons. The presence or absence of boron in this ordered structure is discussed on the basis of difference Fourier syntheses, interatomic distances, structural analysis, and theoretical calculations in relation with the parent structures of the binaries AlB2 and Yb3Si5 (Th3Pd5 type of structure). Theoretical calculations show substantial covalent interactions between the metal and nonmetal elements. The small percentage of silicon atoms, which are missing in these nonstoichiometric compounds, probably allows strengthening boron-metal and boron-silicon bonding. 相似文献
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O. Beneš R. Jardin R.J.M. Konings E. Colineau F. Wastin N. Magnani 《The Journal of chemical thermodynamics》2009,41(4):560-563
The enthalpy increments of UPd3 and ThPd3 have been measured using the drop calorimetry for temperature range (480 to 1290) K. The heat capacity curves have been derived using the simultaneous linear regression of our data and the low temperature heat capacity data from previous studies. Furthermore the Schottky contributions for UPd3 were determined by comparing the ThPd3 and UPd3 heat capacity functions and correlated with the theoretical values calculated from the crystal field energy levels. 相似文献
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Oliver Oeckler Christophe Jardin Hansjürgen Mattausch Arndt Simon Jean‐Franois Halet Jean‐Yves Saillard Josef Bauer 《无机化学与普通化学杂志》2001,627(6):1389-1394
Lu3BC3 is prepared by arc‐melting of the elements. The silver colored compound crystallizes in the space group Cmcm (Z = 4, a = 4.9788(3) Å, b = 5.0109(3) Å, c = 15.669(1) Å). The crystal structure contains discrete carbon atoms and CBC units in octahedra and bicapped cubes of metal atoms, respectively. The structural analysis is consistent with the group oxidation states (Lu3+)3(C4–)(CBC5–). Extended Hückel and LAPW calculations have been performed. Although a semiconducting behavior could be anticipated, the valence band and the conduction band are touching according to LAPW calculations in agreement with the observed metallic conductivity of the compound. 相似文献
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V. N. Panteleev O. Alyakrinskiy A. Andrighetto A. E. Barzakh M. Dubois C. Eleon S. Essabaa O. Bajeat D. V. Fedorov G. Gaubert A. M. Ionan V. S. Ivanov P. Jardin A. Lanchais C. Lau R. Leroy G. Lhersonneau C. Mhamed K. A. Mezilev P. L. Molkanov F. V. Moroz S. Yu. Orlov V. Rizzi M. G. Saint Laurent L. Stroe L. B. Tecchio A. C.C. Villari Yu. M. Volkov 《The European physical journal. Special topics》2007,150(1):297-300
The capacity of uranium carbide target materials of
different structure and density for production of neutron-rich and
heavy neutron-deficient nuclides have been investigated. The
yields of Cs and Fr produced by a 1 GeV proton beam of the PNPI
synchrocyclotron and release properties of different targets have
been measured. Yields and release efficiencies of Cs and Fr
produced from a high density UC target material and from low
density UCx prepared by the ISOLDE method at IRIS in the
collaboration with PARRNe group from Orsay are compared. The
yields from ISOLDE original target are presented for comparison as
well. 相似文献
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In this paper, we address the influence of a blowing-/suction-type distributed forcing on the flow past a blunt-based axisymmetric bluff body by means of direct numerical simulations. The forcing is applied via consecutive blowing and suction slots azimuthally distributed along the trailing edge of the bluff body. We examine the impact of the forcing wavelength, amplitude and waveform on the drag experienced by the bluff body and on the occurrence of the reflectional symmetry preserving and reflectional symmetry breaking wake modes, for Reynolds numbers 800 and 1,000. We show that forcing the flow at wavelengths inherent to the unforced flow drastically damps drag oscillations associated with the vortex shedding and vorticity bursts, up to their complete suppression. The overall parameter analysis suggests that this damping results from the surplus of streamwise vorticity provided by the forcing that tends to stabilize the ternary vorticity lobes observed at the aft part of the bluff body. In addition, conversely to a blowing-type or suction-type forcing, the blowing-/suction-type forcing involves strong nonlinear interactions between locally decelerated and accelerated regions, severely affecting both the mean drag and the frequencies representative of the vortex shedding and vorticity bursts. 相似文献