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1.
2.
Structural and Magnetochemical Studies on KCuGaF6 The crystal structure of KCuGaF6 was determined on the base of X‐ray single crystal data (wR2 = 0.084 for 2476 independent reflections). The compound crystallizes with a = 728.56(4), b = 989.51(6), c = 676.27(3) pm, β = 93.120(5)°, Z = 4 in space group P21/c of the pyrochlore related KCuCrF6 type. The octahedral coordinations [GaF6] and [CuF6] are slightly resp. strongly distorted (mean values Ga‐F: 188.2 pm resp. Cu‐F: 188.2/200.1/227.6 pm). The longest distances Ga‐F and the shortest ones Cu‐F are found within octahedral chains of these two kinds of atoms, running along [100] and [001], resp., and being mutually bridged as well (M‐F‐M in between 114 and 145°). The magnetic mole susceptibilities measured at powders and at a single crystal follow the isotropic Heisenberg model for S = 1/2, if effects of chain disrupture are considered in the form of some paramagnetic portion. No indication of threedimensional magnetic order is observed down to T = 2 K and low magnetic fields H < 100 G. KCuGaF6 (J/k = —71 K for the powder) is distinguished this way from the chain structure compounds KCuAlF6 und Na2CuScF7 (J/k = —76 resp. —59 K) which were also magnetically studied and yield similar antiferromagnetic exchange constants J/k. 相似文献
3.
Structures of Caesium-containing Fluorides. VII. Cs6Ni5F16 – a New Compound in the System CsF/NiF2 and its Crystal Structure Single crystals of a more caesium-containing phase of composition Cs6Ni5F16, forming in the course of solid state CsNiF3 preparation, could be isolated and their structure determined: a = 618.4(1), b = 1. 455.5(2), c = 2145.1(2) pm, space group Cmca, Z = 4, R = 0.030 (1936 independent reflections). The structure contains chains of five face-sharing octahedra, which are connected at their ends via corners to form a zig-zag layer. The Ni? Ni distances within the chains are 264.1 and 270.2 pm, the average Ni? F distance is 202.0 pm. The caesium atoms exhibit 10-, 11-, and 12-coordination. The structural relations to 2L? CsNiF3 and Cs4Ni3F10 are discussed. 相似文献
4.
The Crystal Structure of Na2NiAlF7 — a Contribution to the Problem of the True Space Group of Orthorhombic Weberites The X-ray single crystal structure determination of the orthorhombic weberite Na2NiAlF7 (a = 707.4(2), b = 1003.8(2), c = 731.5(1) pm; Z = 4) was performed in space group Imma, after all reflections hk0 with h(k) = 2n + 1 could be eliminated, as they proved simulated by Renninger effect and/or λ/2 reflections. The alternative space groups Imm2 resp. I212121 of former weberite structure determinations thus became obsolete. The refinement using 880 independent reflections ended at wR = 0.0232. The resulting average distances within the framework of octahedra are Ni? F = 197.3, Al? F = 180.4 pm. 相似文献
5.
Omid Ranaei Siadat Andrée Lougarre Lucille Lamouroux Caroline Ladurantie Didier Fournier 《BMC biochemistry》2006,7(1):12-7
Background
Acetylcholinesterase is irreversibly inhibited by organophosphate and carbamate insecticides allowing its use in biosensors for detection of these insecticides. Drosophila acetylcholinesterase is the most sensitive enzyme known and has been improved by in vitro mutagenesis. However, its stability has to be improved for extensive utilization. 相似文献6.
The Crystal Structures of the Vanadium Weberites Na2MIIVIIIF7 (MII ? Mn, Ni, Cu) and of NaVF4 At single crystals of the vanadium(III) compounds NaVF4 (a = 790.1, b = 531.7, c = 754.0 pm, β = 101.7°; P21/c, Z = 4), Na2NiVF7 (a = 726.0, b = 1031.9, c = 744.6 pm; Imma, Z = 4) and Na2CuVF7 (a = 717.6, b = 1043.5, c = 754.6 pm; Pmnb, Z = 4) X-ray structure determinations were performed, at Na2MnVF7 (a = 746.7, c = 1821.6 pm; P3221, Z = 6) a new refinement. NaVF4 crystallizes in the layer structure type of NaNbO2F2. The fluorides Na2MIIVF7 represent new orthorhombic (MII ? Ni; Cu) resp. trigonal (MII ? Mn) weberites. The average distances within the [VF6] octahedra of the four compounds are in good agreement with each other and with data of related fluorides (V? F: 193.3 pm). The differences between mean bond lengths of terminal and bridging F ligands are 5% in NaVF4, but less than 1% in the weberites. Details and data for comparison are discussed. 相似文献
7.
Valentin Chabert Lucille Babel Michael P. Füeg Maksym Karamash Edwin S. Madivoli Nelly Herault Joana M. Dantas Carlos A. Salgueiro Bernd Giese Katharina M. Fromm 《Angewandte Chemie (International ed. in English)》2020,59(30):12331-12336
Anaerobic microorganisms of the Geobacter genus are effective electron sources for the synthesis of nanoparticles, for bioremediation of polluted water, and for the production of electricity in fuel cells. In multistep reactions, electrons are transferred via iron/heme cofactors of c‐type cytochromes from the inner cell membrane to extracellular metal ions, which are bound to outer membrane cytochromes. We measured electron production and electron flux rates to 5×105 e s?1 per G. sulfurreducens. Remarkably, these rates are independent of the oxidants, and follow zero order kinetics. It turned out that the microorganisms regulate electron flux rates by increasing their Fe2+/Fe3+ ratios in the multiheme cytochromes whenever the activity of the extracellular metal oxidants is diminished. By this mechanism the respiration remains constant even when oxidizing conditions are changing. This homeostasis is a vital condition for living systems, and makes G. sulfurreducens a versatile electron source. 相似文献
9.
10.
Ed. Freise Carl Krug Hermann Babel Louis Duprac und Paul Wenger 《Fresenius' Journal of Analytical Chemistry》1925,67(4):160-162
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