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  • 1
    Electronic Resource
    Electronic Resource
    Reaction of bis(dimethoxyphosphino)dimethylhydrazine (dmpdmh) with Ru3(CO)12: Evidence for facile ligand fragmentation in Ru3(CO)10(dmpdmh) to give Ru4(CO)12[μ-N(Me)N(Me)], Ru3(CO)11[P(OMe)3], and Ru3(CO)9[μ-P(OMe)3] (1999)
    Springer
    Journal of chemical crystallography 29 (1999), S. 587-595 
    Details
    ISSN: 1572-8854
    Keywords: thermolysis ; P—N bond cleavage ; ruthenium clusters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Thermolysis of the cluster Ru3(CO)12 with the bis(phosphanyl)hydrazine ligand (MeO)2PN (Me)N(Me)P(OMe)2 (dmpdmh) in toluene at 75°C furnishes the known clusters Ru4(CO)12 [μ-N(Me)N(Me)] (2) and Ru3(CO)11[P(OMe)3] (3), in addition to the new cluster Ru3 (CO)10(dmpdmh) (1) and the phosphite-tethered cluster Ru3(CO)9[μ-P(OMe)3] (4). The simple substitution product Ru3(CO)10(dmpdmh), a logical intermediate to clusters 2–4, was synthesized by treating Ru3(CO)12 with Me3NO in CH2Cl2 at room temperature, and independent thermolysis reactions using cluster 1 was shown to yield clusters 2–4. The solid-state structure of clusters 2 and 4 were unequivocally established by X-ray diffraction analysis. Ru4(CO)12[μ-N(Me)N(Me)] crystallizes in the orthorhombic space group Pnna (#52), a = 12.913(1), b = 13.3238(6), c = 12.5690(8) Å, V = 2162.5(2) Å3, Z = 4, and d calc = 2.452 g/cm3. Ru3(CO)9[μ-P(OMe)3] crystallizes in the triclinic space group P $$\bar 1$$ a = 9.586(1), b = 14.354(1), c = 14.997(2) Å, α = 89.82(1)°, β = 98.36(1)°, γ = 92.010(8)°, V = 2040.4(4) Å3, Z = 4, and d calc = 2.212 g/cm3. The coordination of the dimethylazo linkage to the four ruthenium atoms in 2 and the phosphorus atom and one of the oxygen atoms of the methoxy groups to the three ruthenium centers in 4 are confirmed by X-ray analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009505020850
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  • 2
    Electronic Resource
    Electronic Resource
    Room temperature ligand fragmentation in the reaction between PhCCo3(CO)9 and Ph2PN(Me)N(Me)PPh2. X-ray diffraction structure of PhCCo3(CO)8[Ph2PP(O)Ph2] (1999)
    Springer
    Journal of chemical crystallography 29 (1999), S. 603-608 
    Details
    ISSN: 1572-8854
    Keywords: ligand fragmentation ; hydrazine ligand ; P-C bond cleavage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The cobalt cluster PhCCo3(CO)9 reacts with the bis(phosphanyl)hydrazine ligand bis(diphenylphosphino)dimethylhydrazine (dppdmh) in CH2Cl2 with added Me3NO to give the monosubstituted cluster PhCCo3(CO)8[Ph2PP(O)PPh2] as the major isolable product. The solid-state structure of this new cluster was unequivocally established by X-ray diffraction analysis, which has confirmed the presence of a noncoordinated (O)PPh2 moiety. PhCCo3(CO)8[Ph2PP(O)Ph2] crystallizes in the triclinic space group P $$\bar 1$$ , a = 12.036(2), b = 12.037(2), c = 15.124(3) Å, α = 84.82(1)°, β = 89.44(2)°, γ = 60.09(1)°, V = 1890.0(6) Å3, Z = 2, and dcalc = 1.540 g/cm3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009509221759
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  • 3
    Electronic Resource
    Electronic Resource
    Reaction of bis(dimethoxyphosphino)dimethylhydrazine (dmpdmh) with PhCCo3(CO)9: synthesis and X-ray characterization of the dmpdmh-bridged polymorphs of PhCCo3(CO)7[(MeO)2PN(Me)N(Me)P(OMe)2] (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 401-407 
    Details
    ISSN: 1572-8854
    Keywords: dmpdmh-Bridged polymorphs ; IR and NMR spectroscopies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The tricobalt cluster PhCCo3(CO)9 reacts with the bis(phosphanyl)hydrazine ligand bis(dimethoxyphosphino)dimethylhydrazine (dmpdmh) to give the monosubstituted cluster [PhCCo3(CO)8]2(dmpdmh) and the disubstituted cluster PhCCo3(CO)7(dmpdmh) as the major products. This latter cluster contains a bridging dmpdmh ligand. Both IR and NMR spectroscopies (31P and 1H) have been employed in the solution characterization of these two clusters. The solid-state structure of PhCCo3(CO)7(dmpdmh) was unequivocally established by X-ray diffraction analysis, which has revealed the presence of two different polymorphs for this particular cluster. The first polymorph crystallizes in the monoclinic space group P21/n, a = 9.7127(7) Å, b = 17.025(2) Å,c = 16.894(1) Å, β = 96.245(5)°, V = 2777.0(4) Å3, Z = 4, and d calc = 1.689 g/cm3; while the second polymorph crystallizes in the orthorhombic space group Pbca, a = 16.925(2) Å, b = 16.208(2) Å, c = 20.541(3) Å, V = 5635(1) Å3, Z = 8, and d calc = 1.665 g/cm3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022420410672
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  • 4
    Electronic Resource
    Electronic Resource
    Chelation of a diphosphine ligand at FeCo2(CO)9(μ3-S): Spectroscopic and X-ray diffraction data for FeCo2(CO)7(bpcd)(μ3-S) (1999)
    Springer
    Journal of chemical crystallography 29 (1999), S. 391-397 
    Details
    ISSN: 1572-8854
    Keywords: diphosphine ligand ; mixed-metal cluster ; electrochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The tetrahedrane cluster, FeCo2(CO)9(μ3-S), reacts with the redox-active ligand, 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd), to give the disubstituted cluster, FeCo2(CO)7(bpcd)(μ3-S), as the sole product. This diphosphine-substituted cluster contains a cobalt-bound, chelating bpcd ligand. Both IR and 31P NMR spectroscopies have been employed in the solution characterization of FeCo2(CO)7(bpcd)(μ3-S), and the solid-state structure has been unequivocally established by X-ray diffraction analysis. FeCo2(CO)7(bpcd)(μ3-S) crystallizes in the monoclinic space group C2/c, a = 34.494(3) Å, b = 11.4194(9) Å, c = 18.634(2) Å, β = 98.103(7)°, V = 7266.7(9) Å3, Z = 8, and dcalc = 1.584 g/cm3. Cyclic voltammetric studies on FeCo2(CO)7(bpcd)(μ3-S) reveal the presence of two quasireversible redox responses assigned to the 0/1− and 1−/2− redox couples. The orbital composition of these redox couples has been examined by carrying out extended Hückel MO calculations on the model complex FeCo2(CO)7(H4-bpcd)(μ3-S), with the results being compared to related cluster compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009502708303
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  • 5
    Electronic Resource
    Electronic Resource
    Borel Subalgebras Redux with Examples from Algebraic and Quantum Groups (2000)
    Springer
    Algebras and representation theory 3 (2000), S. 213-257 
    Details
    ISSN: 1572-9079
    Keywords: Borel subalgebra ; quantum groups ; linear algebra ; homological functors ; representation theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Both building upon and revising previous literature, this paper formulates the general notion of a Borel subalgebra B of a quasi-hereditary algebra A. We present various general constructions of Borel subalgebras, establish a triangular factorization of A, and relate the concept to graded Kazhdan–Lusztig theories in the sense of Cline et al. (Tôhoku Math. J. 45 (1993), 511–534). Various interesting types of Borel subalgebras arise naturally in different contexts. For example, `excellent" Borel subalgebras come about by abstracting the theory of Schubert varieties. Numerous examples from algebraic groups, q-Schur algebras, and quantum groups are considered in detail.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009980101091
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  • 6
    Electronic Resource
    Electronic Resource
    Modeling generalized stacking faults in Au using the tight-binding potential combined with a simulated annealing method (2002)
    Springer
    The European physical journal 28 (2002), S. 45-48 
    Details
    ISSN: 1434-6036
    Keywords: PACS. 61.72.Nn Stacking faults and other planar or extended defects – 71.15.Nc Total energy and cohesive energy calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The tight-binding potential combined with a simulated annealing method is used to study the generalized stacking fault (GSF) structure and corresponding energy of gold. The potential is chosen to fit band structures and total energies from a set of first-principle calculations [Phys. Rev. B 54, 4519 (1996)]. It is found that the relaxed stacking fault energy (SFE) and unstable SFE are equal to 46 and 102 mJ/m2, respectively, and are in good agreement with first principles calculations and experiment. In addition, the structure properties of the relaxed GSF of metal Au are also presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjb/e2002-00197-6
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  • 7
    Electronic Resource
    Electronic Resource
    Magnetoconductance oscillations in semiconductor-superconductor junctions with a laterally isolating barrier layer inside semiconductor region (2003)
    Springer
    The European physical journal 34 (2003), S. 237-246 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The oscillatory characteristics of magnetoconductance for a junction composed of a superconductor and a semiconductor, in which two parallel quantum wave guides are coupled with each other through a potential barrier layer, are studied systematically. To model the imperfectness of the interface, we introduce a $\delta-$ function scattering potential barrier lying close to the interface of the junction. The magnetoconductance oscillations (MCO) in this system stem from two sources: one is the interference of wave functions of quasi-particles due to multiple Andreev reflections at the interface; the other is attributed to the variation of the number of the propagation modes when introducing the isolating barrier layer. The introduction of the isolating layer in the quantum wave-guides strongly modifies MCO. We also present a physical picture for the MCO based on a phenomenological argument. The theoretically fitted results are in good agreement with numerical ones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjb/e2003-00217-1
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  • 8
    Electronic Resource
    Electronic Resource
    Ca2+ Ultrastructural Distribution in Root Apical Cells of Wheat Under Aluminum Stress (2000)
    Springer
    Bulletin of environmental contamination and toxicology 65 (2000), S. 222-227 
    Details
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s0012800118
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  • 9
    Electronic Resource
    Electronic Resource
    Environmental changes documented by sedimentation of Lake Yiema in arid China since the late Glaciation (1999)
    Springer
    Journal of paleolimnology 22 (1999), S. 159-169 
    Details
    ISSN: 1573-0417
    Keywords: lake record ; Holocene environmental changes ; arid northwestern China
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract In this study, a 6 m long core (16,000 BP) at the center of the dry Lake Yiema, a closed lake of Shiyang River drainage in Minqin Basin of the arid northwestern China, was retrieved to recover the history of climate changes and lake evolution in the area. Five radiocarbon dates on organic matter were obtained. A chronological sequence is established based on these five dates and other dates from nearby sites. Magnetic susceptibility, particle size and chemical composition were analysized for climate proxies. The proxies indicate that a drier climate prevailed in the Shiyang River drainage during the last glacial. Lake Yiema was dry and eolian sand covered most part of the lake basin. During the early and middle Holocene, a moister climate prevailed in the drainage. Climate became dry stepwise with an abrupt transition from one stage to another during the entire Holocene and became driest since about 4,200 BP. Maximum dry climate spells occurred at about 12,000-10,000 BP and after about 4,200 BP. A dry climate event also existed at about 7,600 BP. Periodical sand storms with about 400-yr cycle happened during the middle Holocene. Desiccation processes of the lake started at 4,200 BP, and were accelerated since the last 2,500 yrs by the inflow water diversion for agriculture irrigation. During the past 2,500 yrs, the lake size has been closed associated with the human population, implying that the human impact has been accelerating the lake desiccation superimposed on the natural climate deterioration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008093300257
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  • 10
    Electronic Resource
    Electronic Resource
    A boundary integral equation formulation for the Reissner's plates resting on two-parameter foundation (1992)
    Springer
    Acta mechanica solida Sinica 5 (1992), S. 85-98 
    Details
    ISSN: 0894-9166
    Keywords: two-parameter foundation ; Reissner's plates ; fundamental solutions ; BEM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract In this paper a boundary integral equation formulation for the Reissner's plates resting on a two-parameter foundation is established. With the aid of the Hormander Operator method, the equations of the corresponding fundamental solutions are converted into a sixth order partial differential equation with a scale function as an unknown. In order to reduce the equation further, two auxiliary functions are introduced. They satisfy a second and a fourth order equation respectively. The expressions of the auxiliary functions can be derived easily. The fundamental solutions of the Reissnei's plates on the two-parameter foundation arc expressed by a linear combination of the auxiliary functions and their derivatives. The boundary integral equations are formulated by the use of the weighted residual procedure. The fundamental solutions obtained are taken as the kernel functions of the boundary integral equations. A few examples are studied. The numerical results show high accuacy and efficiency of the present formulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02215630
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