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  • 2000-2004  (4)
  • copper  (2)
  • Cartilage stresses  (1)
  • sediment
  • 1
    Electronic Resource
    Electronic Resource
    Crystal structure and spectroscopy of a most unusual Cu(II) coordination compound containing an infinite chain of lattice ligand interwoven with stacked sheets of neutral bis(2-aminopyrimidine-bridged) copper ions: X-ray structure of [Cu(ampym)2(H2O)2(CF3SO3)2](ampym)2(ampym)2 (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 11-16 
    Details
    ISSN: 1572-8854
    Keywords: aminopyrimidine ; copper ; stacking ; hydrogen bonding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Reaction of Cu(II) triflate with an excess of 2-aminopyrimidine (ampym) in ethanol followed by slow crystallization results in a most unusual crystal lattice, which can be considered as consisting of two interpenetrating sublattices. The compound analyzes as [Cu(ampym)2(H2O)2(CF3SO3)2(ampym)4]. Crystal data: Triclinic, P $$\overline 1$$ , a = 7.6179(5), b = 11.4311(14), c = 11.8373(13) Å, α = 84.098(9), β = 79.998(7), γ = 84.253(8)°, Vol = 1010.151(8) Å, Z = 1, Dcalc = 1.592 g/cm3. One part of the lattice consists of the unprecendented linear chain of neutral ampym molecules; the chain is built up by Watson–Crick type bis-hydrogen bonds between imine N atoms and N-H groups of the NH2. This ampym chain is apparently stabilized by the other part in the crystal lattice, which can best be described by starting from the centrosymmetric trans-CuII(ampym)2(H2O)2 ion (Cu-N = 2.01 Å; Cu-O = 1.94 Å). This Cu ion is coordinated by two monodentate ampym ligands, two water molecules and two semi-coordinating triflate oxygen atoms. The Cu chromophore is held in position by hydrogen bonding towards a triflate ion (two times for symmetry reasons), and (again two times) a free ampym ligand. The triflate ion bridges a water hydrogen to a next-neighboring free ampym ligand. The noncoordinating ampym molecule has four bonding sites, of which two are used in H-bonding with the coordinated ligand, one with the triflate and the last one with the water hydrogen atom. The noncoordination ampym molecules in this sublattice finally form aromatic stacks with coordinated ampym and with itself in pairs (ring-ring distance 3.77-3.80 Å).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009533729785
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Redox processes in recent sediments of the river Meuse, The Netherlands (2000)
    Springer
    Biogeochemistry 48 (2000), S. 217-235 
    Details
    ISSN: 1573-515X
    Keywords: diagenesis ; modelling ; organic matter ; pore water ; redox ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Pore-water concentrations of inorganic solutes were measured at four locations in a recent sedimentation area of the river Meuse in The Netherlands. The pore-water concentration profiles were interpreted using the steady state one-dimensional reaction/transport model STEADYSED1. This model explicitly accounts for the organic matter degradation pathways and secondary redox reactions. Results show that the model reproduces the measured pore-water profiles of redox species reasonably well, although significant divergence is observed for pH. The latter is due to the absence of pH buffering by CaCO3 in the model. At all locations, methanogenesis is the major pathway of organic matter degradation below 3 cm from the sediment-water interface. However, organic matter degradation rates by methanogenesis may be overestimated, because methane ebullition is not included. Differences in profiles of redox-sensitive ions among the four locations are explained by differences in depositional conditions, in particular the sediment accumulation rate and supply of organic matter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006268325889
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  • 3
    Electronic Resource
    Electronic Resource
    Interstitial Fluid Pressurization During Confined Compression Cyclical Loading of Articular Cartilage (2000)
    Springer
    Annals of biomedical engineering 28 (2000), S. 150-159 
    Details
    ISSN: 1573-9686
    Keywords: Biphasic theory ; Diarthrodial joints ; Cartilage stresses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The objective of this study was to experimentally verify the well-accepted but untested hypothesis that cartilage interstitial fluid pressurizes variously under the action of an applied cyclical stress in confined compression over a range of loading frequencies, contributing significantly to the cartilage dynamic stiffness. Eighteen bovine cartilage cylindrical samples were tested under load control using a porous indenter in a confined compression chamber fitted with a microchip pressure transducer at its bottom. Over a static stress of 130 kPa, a cyclical stress of amplitude 33 kPa was applied with the indenter at frequencies ranging from 0.0001 to 0.1 Hz. The cartilage interstitial fluid pressure and deformation were measured simultaneously as a function of time. The displacement response at the lowest tested frequency was curvefitted in the time domain to determine the linear biphasic material properties, HA=0.70±0.10 MPa and k 0=2.4 × 10-16±0.64 × 10-16m4/Ns. These properties were employed in the biphasic theory to predict the interstitial fluid pressure response and compare it to experiment, resulting in nonlinear coefficients of determination ranging from r2=0.89 ± 0.15 to 0.96±0.03 depending on frequency. It was found for the samples of this study that above a characteristic frequency of 0.00044 Hz, the magnitude and phase of fluid pressurization matched the applied stress, reducing the tissue strain at the impermeable bottom surface to nearly zero. The findings of this study verify the hypothesis that cartilage dynamic stiffness derives primarily from flow-dependent viscoelasticity as predicted by the linear biphasic theory; they demonstrate experimentally the significance of interstitial fluid pressurization as the fundamental mechanism of cartilage load support over a wide range of frequencies. © 2000 Biomedical Engineering Society. PAC00: 8719Rr
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1114/1.239
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  • 4
    Electronic Resource
    Electronic Resource
    Crystal structure and spectroscopy of bis-[bis(2-benzimidazolyl)propane]copper(II) bis(triflate)monohydrate, a copper complex with a geometry intermediate between tetrahedral and square planar (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 793-797 
    Details
    ISSN: 1572-8854
    Keywords: copper ; bis(benzimidazoles) ; crystal structure ; infrared
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structure of a mononuclear copper(II) compound with the ligand bis(2-benzimidazolyl)propane (abbreviated as tbz) is reported. The compound [Cu(tbz)2](CF3SO3)2(H2O) crystallizes in the triclinic space group P $$\bar 1$$ , with a = 12.363(6), b = 13.218(9), c = 15.365(8) Å, α = 82.74(5), β = 68.04(4), γ = 65.30(5), and Z = 2. The Cu(II) atom has a geometry intermediate between tetrahedral and square planar, consisting of four nitrogen atoms of two tbz ligands. The Cu—N—Cu angles are about 135°, while the dihedral angle between them amounts to 62° (0° for square planar and 90° for a tetrahedron). Ligand field bands are observed at 10.2 × 103, 13.8 × 103, and 20.3 × 103 cm−1, while the most characteristic infrared vibrations of the triflate anion are observed at 1273, 1260, 1238, 1221, 1171, and 1157 cm−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1013276325343
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    Paper (German National Licenses)
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