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  • crystal structure  (79)
  • phosphorus  (73)
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  • Springer  (204)
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  • 1995-1999  (204)
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  • 1999  (204)
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  • Springer  (204)
  • American Chemical Society
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  • 1995-1999  (204)
  • 1990-1994
  • 1955-1959
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 29 (1999), S. 1171-1176 
    ISSN: 1572-8838
    Keywords: alloys ; cyclic voltammetry ; electrodeposition ; electroless deposition ; nickel ; phosphorus ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electroless Ni–Zn–P alloy deposition from a sulphate bath, containing sodium hypophosphite as reducer, was investigated. To increase the plating rate, the deposition parameters were optimized. The effect of process parameters (T, pH and [Zn2+]) on the plating rate and deposit composition was examined and it was found that the presence of zinc in the bath has an inhibitory effect on the alloy deposition. As a consequence, the percentage of zinc in the electroless Ni–Zn–P alloys never reaches high values. Using cyclic voltammetry the electrodeposition mechanism of Ni–Zn–P alloys was investigated. It was observed that the zinc deposition inhibits the nickel discharge and, as a consequence, its catalytic activity on hypophosphite oxidation. It was also found that increase in temperature or pH leads to the deposition of nickel rich alloys.
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  • 2
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    Journal of chemical crystallography 29 (1999), S. 203-206 
    ISSN: 1572-8854
    Keywords: Manganese(III) ; Schiff base ; hydrogen bonding ; crystal structure ; Jahn-Teller distortion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The manganese complex, (Mn2(III)(salpa)2Cl2(H2O)2], has been prepared and its structure determined using x-ray crystallography. The dimer is a di-μ2-alkoxo complex which is a six-coordinate manganese dimer with unsupported alkoxide bridges and a rare example of a chloride- and water-containing manganese dimer. The complex crystallizes in the monoclinic space group P21/c with a = 9.315(5), b = 11.130(4), c = 11.637(5) Å, β = 104.33(3)°, V = 1169.0(9) Å3, and Z = 2. The structure comprises discrete binuclear clusters in which the metal atoms are bridged by two alkoxo oxygens of the salpa2− ligands. The Mn—O and Mn—N distances are in good agreement with those found for other manganese(III) Schiff base complexes. The Mn—Cl and Mn—O3 distances are 2.585(2) and 2.371(2) Å, respectively, and the Mn ··· Mn distance is 3.001(1) Å. In the crystal, there are two types of hydrogen bonding between the H2O molecule and the Cl atom with Cl ··· H(H2O) distance of 2.33(6) (intramolecule: −1 + x, y, −1 + z) and 2.68(6) Å (intermolecule: −1 + x, 0.5−y, −0.5 + z).
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  • 3
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    Journal of chemical crystallography 29 (1999), S. 243-246 
    ISSN: 1572-8854
    Keywords: Thorium ; dimethoxyethane ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The molecular structure of ThBr4(DME)2 (DME = 1,2-dimethoxyethane), the first structurally characterized thorium complex containing a simple bidentate ether ligand, is described. The eight-coordinate complex presents a distorted dodecahedral geometry, with Th—Br and Th—O bond lengths in the ranges 2.8516(13)–2.8712(13) Å and 2.564(8)–2.620(8) Å, respectively. ThBr4(DME)2 is monoclinic, space group P21/n, a = 7.672(1), b = 14.581(1), c = 15.847(2) Å, β = 102.24(1)°, V = 1732.4(3) Å3, and Z = 4.
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  • 4
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    Journal of chemical crystallography 29 (1999), S. 295-298 
    ISSN: 1572-8854
    Keywords: Copper ; crystal structure ; synthesis ; Schiff base ligand
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title complex Cu(C8H7O2N)2(OH2) crystallized in the orthorhombic space group, Pbca with unit cell parameters: a = 15.242(2), b = 11.782(4), c = 17.946(4) Å, and Z = 8. Two nitrogen atoms, two phenolic oxygen atoms of the ligand, and one water molecule are coordinated with copper to form a distorted tetragonal pyramidal polyhedron.
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  • 5
    ISSN: 1572-8854
    Keywords: Europium ; terbium ; betaine ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Three dimeric lanthanide(III) complexes, [Eu2(bet)8(H2O)4](CIO4)6 (1), [Tb2(bet)8(H2O)4](ClO4)6 (2), and [Eu2(bet)4(H2O)8] Cl6·6H2O (3) (bet = Me3N+CH2COO−, trimethyl-aminoacetate), have been prepared and structurally characterized by X-ray crystallography. Complex 1 crystallizes in the monoclinic space group P21/c, with a = 11.7807(8), b = 27.757(5), c = 11.7980(8) Å, β = 99.500(4)°, V = 3805.1(8) Å3, and Z = 2. Complex 2 is isomorphous to complex 1, crystallizing in the monoclinic space group P21/c, with a = 11.7769(14), b = 27.725(3), c = 11.795(5) Å, β = 99.668(14)°, V = 3797(2) Å3, and Z = 2. Complex 3 crystallizes in the orthorhombic space group Pbca, with a = 12.5664(8), b = 17.8645(9), c = 22.2573(8) Å, V = 4996.6(4) Å3 and Z = 4. Both complexes 1 and 2 comprise quadruply carboxylate-O,O′-bridged [M2(bet)4]6+ dimeric cores (M = Eu, Tb), and each metal ion is further coordinated by two terminal aqua ligands and two monodentate bet carboxylates to form a distorted square-antiprismatic coordination geometry. Complex 3 also has a [Eu2(bet)4]6+ core, in which two bet ligands act in the η1:η1:μ2 bridging fashion, and the other two bet ligands in the less common η2:η1:μ2 bridging fashion, namely bridging-chelate mode. Each europium(III) ion in complex 3 is further coordinated by four water molecules to complete a monocapped square antiprism.
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  • 6
    ISSN: 1572-8854
    Keywords: crystal structure ; copper(II) complexes ; dinuclear complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A chemical Janus, binuclear copper(II) complexes, {[Cu(TPA)Cl][Cu(BPA)Cl]}(ClO4)2 (TPA = Tris(2-pyridylmethyl) amine, BPA = bis-(2-pyridylmethyl)amine) containing two different ligands has been synthesized and characterized by X-ray single crystal analysis. Crystal data: triclinic, space group P1$sm, a = 12.529(3), b = 12.655(3), c = 13.458(3) Å, α = 70.48(3), β = 67.40(3), γ = 75.81(3)°, D x = 1.648 mg m−3, and Z = 2. The molecular structure shows that the binuclear copper complex consists of two positive cation and two perchlorate anions. The positive cations moieties have different ligands. Cu(1) is coordinated by four nitrogen atoms from TPA and one chloride atom, forming a square-pyramidal geometry, whereas the coordinate number of Cu(2) is four, three of which are from BPA, one from chloride. There are two weak bonds between the Cl(2a) ion and the Cu(2) ion (2.844 Å) and the distance of Cu(2)=O(13) is 2.750(9) Å.
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  • 7
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    Journal of chemical crystallography 29 (1999), S. 513-521 
    ISSN: 1572-8854
    Keywords: nanotechnology ; molecular devices ; triptycene ; crown ether ; crystal structure ; thallium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The incorporation of 9,10-triptycene unit in a crown ether is examined from a structural perspective. Insertion of a triptycene group into 18-crown-6 stretches the crown into an ellipse, as seen in structures presented here of 9,10-triptyceno-22-crown-6 and its thallium complex. Symmetric addition of two triptycene groups into 18-crown-6 results in the sterically congested bis(9,10-triptyceno)-26-crown-6, whose crown cavity is filled with the π-clouds of two arene groups. The larger bis(9,10-triptyceno)-32-crown-8 is more sterically relaxed. The structures of these bis(triptyceno)crown ether molecules are the first with two triptycene groups simultaneously linked through their 9 and 10 positions, thereby forming a simple molecular gearing mechanism. The compound 9,10-triptyceno-22-crown-6 (1) crystallizes in the orthorhombic space group Pbca with a = 10.7962(7), b = 15.826(3), c = 31.147(5) Å, V = 5321.8(12) Å3, and Z = 8; its complex with TlNO3 (Tl-1) crystallizes in the monoclinic space group P21/c with a = 8.1884(14), b = 19.552(2), c = 20.575(4) Å, β = 97.062(8)°, V = 3269.2(9) Å3, and Z = 4; bis(9,10-triptyceno)-26-crown-6 (2) crystallizes in the triclinic space group P $$\bar 1$$ with a = 8.6488(11), b = 10.7718(12), c = 12.3324(12) Å, α = 111.58(1), β = 100.55(1), γ = 106.43(1)°, V = 970.3(5) Å3, and Z = 1; and bis(9,10-triptyceno)-32-crown-8 (3) crystallizes in the orthorhombic space group Pna21 with a = 20.186(3), b = 8.558(2), c = 25.623(2) Å, V = 4426.2(14) Å3, and Z = 4.
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  • 8
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    Journal of chemical crystallography 29 (1999), S. 555-560 
    ISSN: 1572-8854
    Keywords: alkylammonium chloroantimonates(III) ; hydrogen bonds ; disorder ; lone electron pair ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structure of [(CH3)3NH]2Sb3Cl11 (space group P21/n; a = 10.374(2), b = 23.723(5), c = 11.884(2) Å, β = 113.46(3)°; V = 2682.9(9) Å3) consists of a structurally novel [Sb3Cl2− 11] anion and two crystallographically nonequivalent trimethylammonium cations. The anion is composed of three deformed octahedra in the asymmetric part of the unit cell. The octahedra are connected with each other by edges and corners forming a characteristic polyanionic layer. Trimethylammonium cations, one ordered and one disordered, are connected to the inorganic sublattice by N—H· · ·Cl hydrogen bonds.
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  • 9
    ISSN: 1572-8854
    Keywords: crystal structure ; complexes ; pteridine ; lumazine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Single-crystal X-ray diffraction studies have been performed on the complex cis-diaqua-bis(1,3-dimethylpteridine-2,4(1H,3H)-dione-O4,N5) copper(II) perchlorate monohydrate, [Cu(DLM)2(H2O)2](ClO4)2 · H2O. This compound crystallizes in the orthorhombic system, P212121 space group, Z = 4 with a = 8.749(1) Å, b = 14.213(1) Å, c = 21.200(2) Å, and V = 2636.2(4) Å3. The metal ion is surrounded in octahedral geometry by two mutually quasi-perpendicular N5,O4-coordinated lumazine chelators with the O4 atoms trans and the N5 atoms cis. The polyhedron is completed by two cis-coordinated water molecules. The absolute configuration of the complex can be described, following Bailar's nomenclature, as the enantiomer Λ of the stereoisomer 4M. A three-dimensional hydrogen-bond network is defined by water molecules, perchlorate anions, and the O2 of the pteridine A.
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  • 10
    ISSN: 1572-8854
    Keywords: dodecanuclear heterobimetallic ; molybdenum-copper cluster ; cage ; μ6-S ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The complex (Ph4P)2[Mo2S2O2(S2)(S4)] reacts with CuBr to give the dodecanuclear heterobimetallic Mo—Cu—S cage cluster: (Ph4P)2[{Mo2Cu2O2S2(S2)2}3(μ6-S)] (1), which crystallizes in the triclinic space group P1¯, a = 14.445(5), b = 15.396(5), c = 18.858(5) Å, α = 103.12(3), β = 101.93(2), γ = 113.92(3)°, and V = 3517(2) Å3 for Z = 2. The anion 1 can be described as a cage with S2− at the center binding to six Cu atoms; the cage has two big windows each composed of a puckered Cu3S6 9-membered ring.
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  • 11
    ISSN: 1572-8854
    Keywords: copper(II) complexes ; 2,6-diacetylpyridine derivative ; open-chain ligand ; crystal structure ; trigonal-bipyramidal geometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound was obtained by a template synthesis from 2,6-diacetylpyridine, ethylhydrazinoacetate and CuCl2·2H2O (molar ratio 1:2:1, in methanol), and its structure has been determined by single-crystal X-ray diffraction: monoclinic space group P21/c, a = 13.906(5), b = 18.199(6), c = 16.641(6) Å, β = 107.18(3)°, and z = 4. The ligand was found to be tridentate in a trigonal-bipyramidal coordination geometry with two chloride ligands. There are two independent complex molecules, one of which is hydrogen bonded to the water of crystallization.
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  • 12
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    Journal of chemical crystallography 29 (1999), S. 629-633 
    ISSN: 1572-8854
    Keywords: heterometallic polymeric cluster ; polythiometalate ; synthesis ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The complex (NH4)2 WS4 reacts with AgNO3 and La(NO3)3 · 6H2O in a mixture of DEF/DMF (DEF—N,N′-diethylformamide), to give a new heterometallic square-chain polythiometalate {[W4Ag5S16]2 · [La(DEF)2(DMF)6] · [La(DEF)4(DMF)4]}n (1). 1 crystallizes in the monoclinic space group P2/c, a = 19.5534(8), b = 16.9552(6), c = 22.3479(9) Å, β = 106.053(1)°, V = 7120.1(5) Å3, and Z = 2. The anion polymeric chain of 1 can be regarded as an octanuclear cyclic cluster of [W4Ag4S16]4− fragments linked through Ag+ ions. The polymeric chain is extended through the parallel edges of the square unit. The mean W—Ag distance is 2.963(16) Å. The La3+ cations are coordinated by different solvent molecules, the average La—O bond of these large trivalent cations is 2.47(1) Å.
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  • 13
    ISSN: 1572-8854
    Keywords: oxabicyclo[3.2.1]octadiene ; absolute configuration ; asymmetric synthesis ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The compound under investigation crystallizes in the noncentrosymmetric orthorhombic space group P212121 with a = 7.9358(11), b = 11.0532(13), c = 29.2425(43) Å, volume = 2565.0(6) Å3, and Z = 4. The C23H34O8Si molecule contains three chiral centers (one of which is of known configuration, based upon an (R)-pantolactone auxillary group). We have determined the absolute configuration of this species (via the anomalous dispersion of Si relative to C and O) and show that it is consistent with the known configuration of the (R)-pantolactone moiety.
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  • 14
    ISSN: 1572-8854
    Keywords: oxabicyclo[3.2.1]octadiene ; absolute configuration ; asymmetric synthesis ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The compound under investigation crystallizes in the noncentrosymmetric monoclinic space group P21 with a = 9.1798(23), b = 6.6606(18), c = 17.6591(41) Å, β = 94.342(20)° and Z = 2. The C20H30O6Si molecule contains three chiral centers (one of which is of known configuration, based upon an (R)-pantolactone auxiliary group). We have determined the absolute configuration of this species (via the anomalous dispersion of Si relative to C and O) and show that it is consistent with the known configuration of the (R)-pantolactone moiety
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  • 15
    ISSN: 1572-8854
    Keywords: 2,2′-biimidazole ; diester ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract 1,1,′-Di(ethylpropionato)-2,2′-biimidazole, C16H22N4O4, crystallizes from ice-cold ethanol in the space group P $$\bar 1$$ , with a = 4.6742(9), b = 9.1119(13), c = 10.175(2) Å, α = 96.22(1), β = 96.29(2), γ = 97.53(1)°, and Z = 1. The molecule crystallizes with coplanar rings and the substituents assume a trans conformation with a center of inversion between the bridging carbon atoms.
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  • 16
    ISSN: 1572-8854
    Keywords: Hg coordination ; crystal structure ; organomercury derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of the title compound, Hg[S2P(OPri)2]2, has been determined by single-crystal X-ray diffraction. The compound crystallizes in the centrosymmetric P21/c space group with a = 11.800(1), b = 8.925(2), c = 22.167(2) Å, β = 94.988(7)°, and Z = 4. The same compound has been previously reported but the structure is described there in the space group C2/c. In both cases, one phosphorodithioate moiety acts as a chelating group and the other as a bridging group between neighboring mercury atoms (related to one another by the twofold screw axis), giving rise to an infinite polymer along the direction of the b axis. It turns out that in spite of the difference in space group symmetry, the structures are remarkable similar in that they are formed from infinite polymers of similar geometry. The coordination around the Hg ion shows, however, significant differences, mainly for the bridging Hg—S(4) bond length, which is 0.16 Å smaller than that previously reported.
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  • 17
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    Journal of chemical crystallography 29 (1999), S. 329-333 
    ISSN: 1572-8854
    Keywords: Carbene ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Base-promoted reaction of 11-methylenepentacyclo[5.4.0.02,6.03,10.05, 9]undecan-8-one (5) with diethyl diazomethylphosphonate when performed in the presence of excess cyclohexene, resulted in the formation of the corresponding cycloalkylidenecarbene, 6, which subsequently was trapped in situ to afford 8-methylene-11-(7′-bicyclo[4.1.0]heptylidene)pentacyclo-[5.4.0.02, 6.03, 10.05, 9]undecane (7, obtained in 44% yield as a mixture of exo, endo isomers). Subsequent reaction of 7 with dichlorocarbene (generated under phase transfer catalytic conditions) produced the corresponding mono- and di-:CCl2 adducts [i.e., 8 (64% yield) and 9 (5% yield), respectively]. The structure of 9 was established unequivocally via application of single crystal X-ray analysis: Triclinic, P1¯, a = 6.276(2), b = 8.700(2), c = 18.550(3) Å, α = 76.52(3), β = 87.59(3), γ = 70.88(4)° Z = 2; D calc 1.486 g cm−3.
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  • 18
    ISSN: 1572-8854
    Keywords: crystal structure ; manganese complex ; disubsituted oxamide ; addition compound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structure of the addition compound, Mn(phen)3(PMoxdH2)(ClO4)2 was established by X-ray crystallography, where PMoxdH2 is N,N′-bi(2-pyridylmethyl)-oxamide. Six nitrogen atoms of the three 1,10-phenanthroline bind to the manganese ion and the oxygen atom of PMoxdH2 is uncoordinated. The addition compound crystallizes in the monoclinic space group C2/c, with lattice parameters a = 23.780(6), b = 11.948(5), c = 18.466(6) Å, β = 117.38(3)°, V = 4659(3) Å3, and Z = 4.
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  • 19
    ISSN: 1572-8854
    Keywords: pyrazolyl derivative ; substituted cyclopentane ; substituted cyclohexane ; crystal structure ; bidentate ligand
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The species 1,1-di(pyrazol-1-yl)cyclohexane, C12H16N4, crystallizes in the monoclinic space group P21/c with a = 8.340(2), b = 14.281(5), c = 10.153(3) Å, β = 106.86(2)°, and Z = 4. The cyclohexane moiety has the chair conformation. The congener, 1,1-di(pyrazol-1-yl)cyclopentane, C11H14N4, while not isomorphous, also crystallizes in space group P21/c with a = 14.350(2), b = 6.776(1), c = 11.043(2) Å, β = 100.68(1)°, and Z = 4. The cyclopentane ring has a conformation in which four carbon atoms are essentially coplanar, while the fifth (that with the two pyrazolyl substituents) lies 0.63 Å from this plane, resulting in a bend of 41.3° across the C(2)···C(5) vector. The hydrogen atoms in each structure were located directly and their coordinates refined.
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  • 20
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    Journal of chemical crystallography 29 (1999), S. 719-723 
    ISSN: 1572-8854
    Keywords: synthesis ; crystal structure ; independent molecules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The x-ray crystal structure of 4,5-(cis-cyclohexylenedithio)-1,3-dithiole-2-one has been determined. Yellow block shaped crystals of C9H10OS4 crystallize in the space group P $${\bar 1}$$ with cell dimensions a = 8.872(4), b = 9.330(8), c = 14.333(12) Å, α = 95.23(7), β = 91.09(5), γ = 107.60(5)°, V = 1124.8(14) Å3, and Z = 4. This compound has two S---S contacts [3.574, 3.610 Å] shorter than 3.70 Å and the usual disordered ethylene moiety [C(3)—C(8)] of the six-membered ring is fixed by the cis-cyclohexylene subsitituent. This means that it may be a new precursor for conducting and strong near-IR absorbing nickel-dithiolenes. Also, it provides the first example of polymorphism of the dmit derivatives and contains two independent molecules I and II in the asymmetric unit.
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  • 21
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    Journal of chemical crystallography 29 (1999), S. 725-727 
    ISSN: 1572-8854
    Keywords: 2-thiouracil derivatives ; crystal structure ; S-methyl-thiouracil ; hydrogen bonding ; structural methylation and metallation effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract 2-S-Methylthiouracil crystallizes in the triclinic space group P $${\bar 1}$$ with unit cell dimensions a = 5.508(4), b = 7.175(3), c = 8.522(2) Å, α = 80.83(2), β = 80.43(3), γ = 76.86(3)°, and Z = 2. The molecule exists in the crystal in the lactam form and is essentially planar. The molecular packing consists of molecules linked in centrosymmetric hydrogen-bonded pairs. The effects of methylation and subsequent metallation on the 2-thiouracil structure are discussed.
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  • 22
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    Journal of chemical crystallography 29 (1999), S. 797-802 
    ISSN: 1572-8854
    Keywords: synthesis ; crystal structure ; Cu(I) complex ; μ-oxo-bis(2,9-dimethyl-1,10-phenanthroline) ; luminescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The synthesis and crystal structure of a luminescent dinuclear Cu(I) complex as the BF− 4 salt from toluene and methanol containing triphenylphosphine and μ-oxo-bis(2,9-dimethyl-1,10-phenanthroline) is described. The coordination geometry about the Cu(I) center is distorted tetrahedral. An unusual feature of the structure is a pseudo-inversion center located near the oxygen atom at approximately 0.51, 0.26, 0.25, such that all of the atoms except for the oxygen are related by a pseudo-inversion center to another atom in the same molecule, as well as by crystallographic inversion to the other molecule in the unit cell. The complex displays luminescence from an MLCT band in fluid solution and emission from both a metal-centered charge-transfer and intraligand (phenanthroline) state at 77K in a chloroform snow. Crystal data: triclinic, P $$\bar 1$$ , a = 15.163(2), b = 16.985(2), c = 18.731(2) Å, α = 106.458(9), β = 91.416(8), γ = 102.557(9)°, V = 4496(1) Å3, and Z = 2.
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  • 23
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    Journal of chemical crystallography 29 (1999), S. 729-733 
    ISSN: 1572-8854
    Keywords: crystal structure ; yttrium complexes ; isothiocyanate complexes ; octahedral coordination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structural analysis of [(n-C4H9)4N]3[Y(NCS)6] (I) using single-crystal diffraction data and full-matrix least squares refinement has been carried out. The hexaisothiocyanate complex crystallizes in the centrosymmetric triclinic space group P $${\bar 1}$$ (No. 2) with unit cell constants of a = 12.431(1), b = 12.866(1), c = 22.750(2) Å, α = 90.78(1), β = 92.05(1), γ = 96.67(1)°, and Z = 2. The molecular unit consists of three separate cationic tetra-n-butylammonium groups and an independent hexakisisothiocyanatoyttrate anionic group in which the six thiocyanate ligands are octahedrally coordinated through the N atom to the Y central ion. Selected bond distances and angles are presented as well as the synthesis and peripheral studies of (I).
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  • 24
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    Journal of chemical crystallography 29 (1999), S. 793-796 
    ISSN: 1572-8854
    Keywords: copper complex ; crystal structure ; dibenzoylmethane complex
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    Topics: Geosciences , Physics
    Notes: Abstract Bis(dibenzoylmethane)copper Cu(dbm)2 has been synthesized and its structure determined by x-ray diffraction. It crystallizes in the monoclinic system, space group C2/c, with a = 25.936(3), b = 5.9806(8), c = 16.4908(16) Å, β = 114.998(8)°, Z = 4, and V = 2318.3(4) Å3. The Cu atom is located at a symmetry center and surrounded by four O atoms from two dbm molecules to form a plane square coordination environment. On the a–c plane the molecules are orderly arranged to result in a layered structure, and parallel to crystallographic b-axis they form a molecular column due to the effect of aromatic stacking.
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  • 25
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    Journal of chemical crystallography 29 (1999), S. 809-812 
    ISSN: 1572-8854
    Keywords: tungsten(II) ; dibromo ; carbonyl ; diphenylcyclohexylphosphine ; but-2-yne ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract [WBr2(Co)(PPh2Cy)2(η2-MeC2Me)]·CH2Cl2 (Cy = cyclohexyl) crystallizes in the monoclinic space group, P21/n, with a = 10.606(12), b = 23.11(3), c = 18.19(2) Å, β = 106.070(10) Dcalc = 1.610g cm−3 for Z = 4. The tungsten coordination geometry can best be considered as a distorted octahedron, with the but-2-yne ligand occupying one coordination site, which has a trans-Br(2) group. The equatorial plane is made up of trans-PPh2Cy groups, with the bromo and carbonyl ligands occupying the other two sites.
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  • 26
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    Journal of chemical crystallography 29 (1999), S. 837-839 
    ISSN: 1572-8854
    Keywords: acyclonucleoside analog ; 6-(phenyl selenyl) uracil derivative ; crystal structure
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    Topics: Geosciences , Physics
    Notes: Abstract The compound, 1-(ethoxymethyl)-6-(phenylselenyl)-5-ethyl uracil, crystallizes in the monoclinic space group P21/n with unit cell parameters a = 5.304(1), b = 21.261(4), c = 13.996(4) Å, β = 94.30(2)°, and Z = 4. The acyclic chain C1′, O4′, C4′, C5′ is in fully extended form and nearly perpendicular to the uracil base. The molecules are held together by van der Waal's forces.
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  • 27
    ISSN: 1572-8854
    Keywords: mercury halides ; crystal structure
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    Topics: Geosciences , Physics
    Notes: Abstract The synthesis, characterization and single crystal X-ray structure of three compounds of general formula HgI2R (R = phen[1], dmph [2] and bpy[3]) are presented. The crystal data for the three compounds are: [1], triclinic, space group P $$\bar 1$$ (#2) a = 7.902(2), b = 9.479(2), c = 10.002(2) Å, α = 91.45(2), β = 111.34(2), γ = 100.82(2)° [2]: monoclinic, space group C2/c (#15) a = 15.670(3), b = 11.640(2), c = 9.730(2) Å, β = 114.57(3)° [3]: triclinic, space group P1¯ (#2) a = 9.472(1), b = 9.507(1), c = 9.023(1) Å, α = 98.46(1), β = 102.89(1), γ = 119.62(1)°. Compounds [1] and [2] are monomers, with highly distorted tetrahedral environments around Hg. In [3], instead, there is a significant intermolecular I···Hg interaction leading to the formation of softly bound dimers linking two pentacoordinated cations. The structure is compared with related ones in the literature.
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  • 28
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    Journal of chemical crystallography 29 (1999), S. 907-911 
    ISSN: 1572-8854
    Keywords: tungsten(II) ; Iodo ; carbonyl ; cis-bis(diphenylphosphino)ethene ; but-2-yne ; cationic ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The complex [WI(CO)(cis-dppen)(η2-MeC2Me)2]I·CH2Cl2(1) is prepared as a by-product from the reaction of equimolar quantities of [WI2(CO)(NCMe)(η2-MeC2Me)2] and cisdppen {dppen = bis(diphenylphosphino)ethene}. Complex 1, [WI(CO)(cis-dppen)(η2-MeC2Me)2]I·CH2Cl2 crystallizes in the triclinic space group $${\text{P}}\bar 1$$ with a = 11.189(13), b = 12.331(14), c = 15.395(17) Å, α = 83.61(1), β = 86.06(1), γ = 64.48(1)°, U = 1904 Å3, and Z = 2. The metal environment in the cation can best be considered as a distorted octahedron with the two but-2-yne groups taking up individual sites trans to phosphorus atoms of the dppen ligand. The coordination sphere is completed by mutually trans-carbonyl and iodide groups.
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  • 29
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    Journal of chemical crystallography 29 (1999), S. 955-959 
    ISSN: 1572-8854
    Keywords: crystal structure ; intramolecular hydrogen bond ; 4-(1,4-dimethoxy-2-naphthyl)-4-hydroxycyclohexanone
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    Topics: Geosciences , Physics
    Notes: Abstract Intramolecular hydrogen bonding in the solid state is reported for the title compound and its ethylene ketal. The title compound crystallizes in the triclinic space group, $$P\bar 1$$ with a = 9.590(3), b = 9.620(3), c = 9.844(2) Å, α = 97.67(2), β = 105.25(2), γ = 115.47(2), and Z = 2. The ethylene ketal crystallizes in the monoclinic space group, P21/c, with a = 7.230(2), b = 22.639(3), c = 10.839(2) Å, β = 101.47(2), and Z = 4. The intramolecular hydrogen bond length of 1.79 Å is the same for the ketone and ketal, but the O—H---O valence angle is 144° for the ketone and 165° for the ketal.
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  • 30
    ISSN: 1572-8854
    Keywords: neotame ; crystal structure ; methanol solvate ; thermal analysis ; powder X-ray diffractometry ; 13C solid-state nuclear magnetic resonance spectroscopy
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    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of the methanol solvate (empirical formula: 2C20H30N2O5·3CH3OH) of a new dipeptide sweetener, neotame (N-(3,3-dimethylbutyl)-L-α-aspartyl-L-phenylalanine 1-methyl ester), has been determined. Crystal data: a = 9.8989(1), b = 18.1331(1), c = 27.5725(1) Å, orthorhombic, space group P212121, with Z = 4. Each unit cell includes 8 neotame and 12 methanol molecules. Disorder exists in one neotame molecule and one methanol molecule. The crystals were characterized by the following techniques: hot-stage microscopy (HSM), Karl-Fischer titrimetry (KFT), powder X-ray diffractometry (PXRD), differential scanning calorimetry (DSC), thermogravimetry (TGA), 13C solid-state nuclear magnetic resonance (SSNMR) spectroscopy. Under HSM at a heating rate of 10°C/min in silicone oil, the sample melts at 64–84°C and liberates bubbles at 71–86°C. DSC in open pans shows two overlapping endotherms at 56 and 71°C, probably due to melting and desolvation, respectively. TGA in open pans shows 5.9% weight loss due to desolvation below 70°C. Under house vacuum (23 mm Hg) over phosphorus pentoxide at 23°C, the methanol solvate produces pure amorphous anhydrate, which converts to crystalline neotame monohydrate in the presence of moisture.
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  • 31
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    Journal of chemical crystallography 29 (1999), S. 977-982 
    ISSN: 1572-8854
    Keywords: cyano allyl radical ; thermal arrangement ; crystal structure ; isomer ; NMR, MM2
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    Notes: Abstract The preparation, separation, crystal structure and 1H NMR spectra are reported for the two geometrical isomers of 1,1′-bi-3-cyanocyclohex-2-enylidene. The E-isomer crystallized as thin plates in the monoclinic space group P21/n with a = 5.3980(5), b = 7.0757(7), c = 15.300(2) Å, β = 94.571(2)°, and Z = 2. The structure has symmetry C2h. The Z-isomer crystallized as needles in the triclinic space group P1¯ with a = 7.0790(6), b = 11.3155(9),c = 15.386(1) Å, α = 104.943° β = 90.164(2)°, γ = 99.494(2)°, and Z = 4. The compound crystallized with two molecules per asymmetric unit. In C6D6, 1H NMR signals of the 2-vinyl protons appear almost identical. However, in a mixture of C6D6 and pyridine-d 5, the 2-vinyl protons can be distinguished. The structures compare favorably with MM2 calculations.
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  • 32
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    Journal of chemical crystallography 29 (1999), S. 1009-1013 
    ISSN: 1572-8854
    Keywords: crystal structure ; nickel complex ; xanthosine
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    Notes: Abstract The complex [Ni(XsH−1)2(H2O)4]·6H2O (XsH−1: xanthosinate) was isolated from the reaction of nickel carbonate with xanthosine in aqueous solution. The octahedral coordination is supported by the reflectance measurements. Single-crystal X-ray diffraction studies show that the crystals belong to the triclinic P1 space group, with a = 7.152(1), b = 8.830(1),c = 13.783(1) Å, α = 82.024(1)°, β = 86.155(1)°, γ = 70.900(1)°, and D = 1.643 mg/m3, forZ = 1. Nickel is six coordinate with four water molecules, and two N7 atoms from xanthosinato ligands. A complicated hydrogen-bonding network is present, all possible donors taking part in it.
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  • 33
    ISSN: 1572-8854
    Keywords: manganese ; pyridine-2-thiolate ; bis(diphenylphosphino)methane ; carbonyl ; crystal structure
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    Topics: Geosciences , Physics
    Notes: Abstract The dimeric complex [Mn2(μ-pyS)2(CO)6] (1) reacted with 2 M equivalents of both PPh3 and PHPh2 to give the respective monomeric phosphine complexes [Mn(pyS)(L)(CO)3][L = PPh3 (2) and PHPh2 (3)]; with 4 M equivalents of dppm, it yielded the complex [Mn(pyS)(η1-dppm)2(CO)2](4). An X-ray structure determination of 4 shows that it crystallizes in the monoclinic space group P21/n with a = 11.027(3), b = 24.984(7), c = 18.379(5) Å, β = 99.870(8)°, V = 4988(2) Å3, and Z = 4. The complex has an octahedral geometry with the chelating pyS ligand and two CO groups occupying the equatorial sites and the two monodentate dppm ligands lying in the trans positions.
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  • 34
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    Journal of chemical crystallography 29 (1999), S. 1037-1041 
    ISSN: 1572-8854
    Keywords: crystal structure ; imidazolidine ; triazene ; bis-triazene ; methoxy substituent ; π-π stacking
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    Notes: Abstract The crystal and molecular structure of 1,3-di-2-[(4-methoxyphenyl)-1-diazenyl]imidazolidine (1) has been determined by single crystal X-ray diffraction analysis. This novel bis-triazene assumes a close-to planar structure with the aryltriazene moieties aligned in diametrically opposed directions, unlike many other previously reported bis-triazenes, which assume a folded structure. The structure of 1 is compared with the closely related, non-cyclic bis-triazene analogue (2), and also compared with the structure of the simple mono-triazene (3). Crystal data: 1 C17H20N6O2, monoclinic, space group C2/c, a = 34.948(3), b = 5.925(5), c = 8.1225(6) Å, β = 100.8420(10)°, and V = 1652.0(2) Å3, for Z = 4.
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  • 35
    ISSN: 1572-8854
    Keywords: crystal structure ; tritylaziridine ; acrylate ; spectroscopic features
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    Notes: Abstract The crystal and molecular structure of 2-{(R)-1-Hydroxy-1-[(2S)-1-tritylaziridin-2-y1] methy1}acrylate is described. Crystal data: C26H25NO3, orthorhombic, space group P212121, a = 9.6954(5), b = 13.1458(5), c = 16.7885(7) Å, V = 2139.8(2) Å3, Z = 4. The (R,S) diastereomer shows an intramolecular hydrogen bonding N···H—O under formation of a five-membered ring with N···O distance of 2.664 Å. IR, 1H NMR and 13C NMR data are discussed. The 1H NMR of the (R,S) diastereomer shows a singlet- whereas the (S,S) diastereomer exhibits a doublet-pattern for the hydroxyl proton.
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  • 36
    ISSN: 1572-8854
    Keywords: absolute configuration ; asymmetric synthesis ; azabicyclo[3.2.1]octadiene ; crystal structure
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    Notes: Abstract The title compound crystallized in space group P21 with a = 12.647(8), b = 14.542(4), c = 17.077(16) Å, β = 97.51(6)°, and D calc = 1.143 mg/m3 for Z = 4. There are two chemically-equivalent C27H41NO8Si molecules in the crystallographic asymmetric unit. Each contains three chiral centers, one of known absolute configuration based upon the (R)-pantolactone,—CH*—CMe2—CH2—O—CO—, moiety. The structural study was greatly complicated by disorder of an —OSiMe2(t-Bu) group in one molecule.
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  • 37
    ISSN: 1572-8838
    Keywords: alloys ; electroless ; microstructure ; morphology ; nickel ; phosphorus ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electroless Ni–Zn–P alloy coatings were obtained on an iron substrate from a sulfate bath at various pH values. The effects of changes in bath pH on alloy composition, morphology, microstructure and corrosion resistance were studied. Scanning electron microscopy was performed to observe the morphological change of the deposits with bath pH. Coating crystallinity was investigated by grazing incidence asymmetric Bragg X-ray diffraction and transmission electron microscopy. A transition from an amorphous to polycrystalline structure was observed on increasing the bath alkalinity, and thus decreasing the phosphorus content of the alloys. A single crystalline phase corresponding to face-centred-cubic nickel was identified in the alloys obtained from a strong alkaline solution. An increase in zinc percentage up to 23% in the deposits does not change the f.c.c. nickel crystalline structure. Corrosion potential and polarization resistance measurements indicated that the corrosion resistance of electroless Ni–Zn–P alloys depends strongly on the microstructure and chemical composition. The deposits obtained at pH 9.0–9.5 and with 11.4–12.5% zinc and 11.8–11.2% phosphorous exhibited the best corrosion resistance.
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  • 38
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    Journal of chemical crystallography 29 (1999), S. 1081-1084 
    ISSN: 1572-8854
    Keywords: cobalt(II) ; bipyridine ; maleato ; crystal structure
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    Topics: Geosciences , Physics
    Notes: Abstract Preparation of the mononuclear cobalt(II) complex, [Co(bipy)(maleato) (H2O)3]·H2O (1) where bipy = 2,2′-bipyridine, were accomplished by reaction of an aqueous solution containing sodium maleate and an ethanolic solution of Co(NO3)2·6H2O and bipy. The crystal structure of complex (1) was determined by X-ray crystallography. The complex crystallizes in the monoclinic space group P21/n with a = 9.477(3), b = 7.660(2), c =23.526 (3) Å, β = 97.64(2)°, V = 1692.6(6) Å3, and Z = 4. The structure consists of discrete mononuclear cobalt molecules. The cobalt atom is six-coordinate and presents a slightly distorted octahedral geometry, which consists of the two imine N atoms of bipy, a terminal carboxylate O atom from maleato ligand, and a water O atom in the basal plane with Co—N bond distances of 2.116(2) and 2.124(3) Å and Co—O distances of 2.075(2) and 2.088(2) Å, respectively. The relatively shorter Co—O distances are due to the trans effect of the bipy ligand. The octahedral coordination is completed the other two water molecules. The coordinate and the lattice water molecules were identified by TG study.
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  • 39
    ISSN: 1572-8854
    Keywords: Rubidium nitroprusside monohydrate ; crystal structure ; properties
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    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of rubidium nitroprusside monohydrate, Rb2[Fe(CN)5NO] · H2O, has been determined from X-ray diffraction data and refined using direct and Fourier methods to R = 0.066 and Rw = 0.075, employing 1894 independent reflections with I 〉 3 (I). The substance crystallizes in the monoclinic space group C2/c (C 6 2h), with a = 13.987(2), b = 10.241(1), c = 18.151(1) Å, β = 110.94°, and Z = 8. Anions are located at C 1 sites, one per asymmetric unit, and are slightly distorted octahedra. TGA, DTA, FTIR, and FTIR Raman results were interpreted on the basis of the formula of the compound, its crystal structure, and the behavior of other nitroprussides.
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  • 40
    ISSN: 1572-8854
    Keywords: crystal structure ; methyl propiolate ; sulfenic acid ; vinyl sulfoxide ; leinamycin
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    Topics: Geosciences , Physics
    Notes: Abstract Evidence for the formation of unstable sulfenic acids (RSOH) as reaction intermediates is commonly provided by trapping these compounds with methyl propiolate. The crystal structure of a vinyl sulfoxide derived from the trapping of a sulfenic acid with methyl propiolate is reported here. The title compound C12H12O5S crystallized in the triclinic space group,P1¯ with unit cell parameters: a = 6.1600(4), b = 9.7286(7), c = 11.3698(8) Å, α = 112.024(1), β = 94.662(1), γ = 95.429(1)°, and Z = 2.
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  • 41
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    Journal of chemical crystallography 29 (1999), S. 1137-1139 
    ISSN: 1572-8854
    Keywords: acyclic nucleoside analog ; acyclovir ; crystal structure
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    Topics: Geosciences , Physics
    Notes: Abstract The compound 9[1-(2-hydroxy ethoxy)-3-hydroxy propyl] guanine crystalizes in the tetragonal system, space group P41212 with a = 11.106 (1), c = 20.558 (2) Å, and Z = 8. The acyclic chain C1′¯O1′¯C4′¯C5′¯O5′ is in the extended configuration and the glycosidic torsion angle (C4¯N9¯C1′¯O1′) is 125.1 (8)°. The molecules are held together by Van der Waal's forces.
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  • 42
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    Journal of chemical crystallography 29 (1999), S. 1205-1210 
    ISSN: 1572-8854
    Keywords: organic sulfate ; crystal structure ; DTA/TG/DSC ; vibrational spectra
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    Topics: Geosciences , Physics
    Notes: Abstract [1-(2-ammoniumethyl) piperazinium] sulfate denoted PIPS has a monoclinic unit cell. The parameters are: a = 6.6521(3), b = 7.8756(5), c = 19.197(1) Å, β = 94.43(1)° and the space group is P21/n. The preparation, thermal analysis, and IR spectrometric investigation are described. The PIPS structure exhibits a complex three-dimensional network of H-bonds connecting all its components.
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  • 43
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    Journal of chemical crystallography 29 (1999), S. 1265-1269 
    ISSN: 1572-8854
    Keywords: crystal structure ; corticosteroid ; de-oxy corticosterone-21-hemisuccinate
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    Topics: Geosciences , Physics
    Notes: Abstract Synthetic glucocorticoid de-oxy corticosterone-21-hemisuccinate crystallizes in the monoclinic space group C2, with a = 21.896(2), b = 7.596(3) and c = 14.291(3) Å, Z = 4. Ring A is a distorted half chair, ring B and C are in the chair configuration and ring D is in the 14α-half chair configuration. The ring junctions B/C and C/D are both trans. The molecule as a whole is slightly convex towards the β-side, with an angle of 18.4(2)° between the C(10)--C(19) and C(13)--C(18) vectors. In addition to packing and stacking interaction, intermolecular hydrogen bonding plays an important role in structural association. The X-ray structure determination of the title compound was undertaken to study its high binding affinity to serum protein like globulin.
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  • 44
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    Journal of chemical crystallography 29 (1999), S. 1291-1293 
    ISSN: 1572-8854
    Keywords: crystal structure ; pyrazolo[3,4-d]pyrimidine ; fungicidal activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound 1-phenyl-3-methylthio-4-imino-5-allyl-pyrazolo[3,4-d]pyrimidine, C15H15N5S, has been synthesized and characterized by x-ray diffraction: orthorhombic, space group Pbca, with a = 17.3480(9), b = 8.5022(5), c = 19.8132(11) Å. Z = 8, V = 2922.4(3) Å3. The compound shows a fully delocalized pyrazolo[3,4-d]pyrimidine system with a sp2 hybridization of the N(4) atom.
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  • 45
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    Journal of chemical crystallography 29 (1999), S. 199-201 
    ISSN: 1572-8854
    Keywords: Manganese (II) ; phenanthroline ; polymeric complex ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A new polymeric manganese(II) complex, [Mn(II)(phen)(ClCH2COO)2]n, was obtained from the reaction of Mn(ClCH2COO)2 with phen and its structure was determined by x-ray crystallography. The complex crystallizes in the monoclinic system, space group C2/c with a = 19.706(4), b = 11.381(3), c = 7.482(3) Å, β = 94.01(3)°, V = 1674.0(8) Å3, and Z = 4. The structure consists of an infinite chain. The manganese atom is located on a twofold axis and presents a distorted octahedral coordination sphere, which consists of the two N atoms of a phen ligand (Mn—N = 2.304(2) Å) and four carboxylato ligands. The Mn···Mn distance within the chain is 4.53 Å, and the carboxylato bridges present a syn-anti conformation.
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  • 46
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    Journal of chemical crystallography 29 (1999), S. 1255-1259 
    ISSN: 1572-8854
    Keywords: crown ether ; crystal structure ; lariat ; sodium
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    Topics: Geosciences , Physics
    Notes: Abstract A dibenzo-14-crown-4 ether with a novel monooxyacetone sidearm is prepared and its structure with sodium perrhenate is determined. The structure crystallizes in P21/c with cell dimensions: a = 8.107(2) Å, b = 28.138(3) Å, c = 10.293(2) Å, and β = 104.173(9)°; giving a volume of 2276.6(7) Å3. This structure is compared to other sodium complexes of dibenzo-14-crown-4 lariat ethers and is found to be the only one with intramolecular bonding between the sidearm and the cation. Possible reasons for this observation are discussed.
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  • 47
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    Journal of chemical crystallography 29 (1999), S. 1271-1275 
    ISSN: 1572-8854
    Keywords: crystal structure ; pregnen ; progestin ; 4-pregnen-21-ol-3,20-dione
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Synthetic steroid de-oxy corticosterone (4-pregnen-21-ol-3,20-dione) crystallizes in the monoclinic space group P21, with a = 11.706(2); b = 11.171(3), c = 13.966(3) Å, and β = 100.94(2)°, Z = 4. Ring A tends to acquire the conformation of a half-boat, rings B and C are in the chair configuration, and ring D is a 13β, 14α-half-chair. The ring junctions B/C and C/D are both trans, whereas the ring junction A/B is quasi-trans. The molecule as a whole is slightly convex toward the β-side, with an angle of 16.01(0.36)° between the C10--C19 and C13--C18 vectors. Molecular packing and stacking interactions play the major role in structural association. Cohesion of the crystal is due to van der Waals interactions.
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  • 48
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    Journal of chemical crystallography 29 (1999), S. 565-569 
    ISSN: 1572-8854
    Keywords: orotic acid complex ; crystal structure ; copper(II) complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The compound [(C5H2N2O4)Cu(H2O)2]n has been synthesized and its structure determined at room temperature. The primary coordination sphere at the Cu ion is square planar with the orotate dianion coordinating at the metal through heterocyclic nitrogen atom and adjacent oxygen of the carboxylate group, the remaining coordination sites are occupied by two water molecules. The orotate dianion is tricoordinated to one copper via N1 and one oxygen of the carboxylato group and to another copper atom via the other oxygen of the carboxylato group. The coordination at copper is extended to five by the other oxygen of the carboxylate group of another orotate molecule. Thus, the molecules are associated to form chains, the carboxylato group acting as a bridge between the metal ions, the orotato-group being tridentate. The title compound crystallizes in the monoclinic space group. P21/n1 with a = 9.515(5), b = 6.925(2), c = 11.861(6) Å, β = 95.285(9)°, D calc = 2.17 g cm−3, and z = 4.
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  • 49
    ISSN: 1572-8854
    Keywords: pseudo-square pyramidal Cu(II) complex ; trans-4-styrylpyridine ; crystal structure ; IR, electronic, and EPR spectra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Single crystals of the title Cu(II) complex, [Cu(stpy)4(ONO2)(ONO2)′] [stpy = trans-4-styryl-pyridine] have been prepared and characterized by elemental and thermal analyses, IR, electronic and EPR spectral measurements, and X-ray crystal structure determination. The complex crystallizes in the monoclinic space group P21/c with unit-cell parameters, a = 12.985(2), b = 22.865(8), c = 17.024(10) Å, β = 112.29(3)°, and Z = 4. The structure consists of discrete monomeric units of [Cu(stpy)4(ONO2)(ONO2)′]. The equatorial positions of the Cu(II) polyhedron are occupied by nitrogen atoms of the four stpy ligands and the axial positions by the oxygens of two unidentate nitrate anions. One of these oxygens is at rather longer distance [2.609(3) Å] and may be considered to be semicoordinated. If this semibond is ignored, the coordination geometry lies closer to an idealized square pyramid than to the trigonal bipyramid geometry. IR spectra reveal nitrogen coordination from stpy and asymmetry in the monodentate oxygen binding of the two nitrate ligands. The optical reflectance band at 600 nm suggests pseudo-square-based pyramidal geometry around Cu(II). Well-resolved Cu(II) hyperfine features in the EPR spectra reveal the absence of exchange interactions between adjacent copper centers. Optical and EPR spectra of a methanolic solution of the complex indicate solvent interactions. Thermogravimetric analysis shows the complex to be stable up to 175°C.
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  • 50
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    Journal of chemical crystallography 29 (1999), S. 475-480 
    ISSN: 1572-8854
    Keywords: crystal structure ; ab initio calculations ; conjugation ; phosphabutadienes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure of 1-phenyl-1-dimethylamino-4,4-bis(trimethylsilyl)-2-aza-3λ3-phosphabutadiene-1,3, Me2N(Ph)C=N—P=C(SiMe3)2 (1), has been determined. Crystal data: triclinic, P1¯, a = 8.975(4), b = 10.001(5), c = 12.440(6) Å, α = 79.04(4), β = 77.98(4), γ = 73.07(4)°, V = 1034.7 Å3, Z = 2, and D c = 1.08 g cm−3. The main geometrical parameters of 1 as well as ab initio (HF/6-31+G**) calculations of the model systems show no clear evidence of high efficiency of the π(C=N)—π (P=C) conjugation.
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  • 51
    ISSN: 1572-8854
    Keywords: contrast agents ; crystal structure ; ortho ester
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract 1-(4-Bromobenzyl)-4-methyl-2,6,7-trioxabicyclo[2.2.2]octane, C13H15BrO3, has been synthesized from 4-bromophenylacetic acid chloride via the oxetan ester (3-methyl-3-oxetanyl)methyl-2-(4-bromophenyl)acetate. The crystal structure of the title compound has been determined at low temperature (120 K), by X-ray diffraction methods. This compound crystallizes in the monoclinic space group P21/n (No. 14), Z = 4, with lattice parametersa = 6.019(5), b = 20.990(5), c = 9.915(2) Å, and β = 101.29(1)°.
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  • 52
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    Journal of chemical crystallography 29 (1999), S. 561-564 
    ISSN: 1572-8854
    Keywords: crystal structure ; Raman spectrum ; silver azide ; azide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Silver nitrate reacts with sodium azide to give white powdery silver azide, which can be crystallized in aqueous ammonia. The compound belongs to orthorhombic space group Ibam with a = 5.600(1), b = 5.980(6), c = 5.998(1) Å, and Z = 4. The layer-type structure is constructed from edge-sharing regular rectangles, each composed of silver atoms at its vertices with an enclosed azide anion in a tilted orientation. The linear and asymmetrical structure of the azide anion in crystalline silver azide has been confirmed by its Raman spectrum.
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  • 53
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    Journal of chemical crystallography 29 (1999), S. 845-848 
    ISSN: 1572-8854
    Keywords: crystal structure ; centrosymmetric ; aminoadamantane derivative ; antiviral ; dispiro compound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Adamantan-1-ammonium 1-adamantanecarboxylate, C21H33NO2 (I) is a novel dispiro-type compound. Aminoadamantane derivatives, in which the spiro carbon atoms are part of heterocyclic rings, are of potential interest as biological active substances and antiviral agents. Complex (I) crystallizes in the centrosymmetric space group C2/c (No. 15) with eight molecules in the unit cell with a = 25.227(4), b = 6.527(1), c = 22.489(4) Å, and β = 90.75(1)°. The two spiro units are a 1-adamantylammonium cation and a 1-adamantane carbonyloxy anion. The complex units are stabilized by a network of intermolecular carbonyloxy-to-amine hydrogen bonding and van der Waals cohesive forces. Germane bond lengths are: C—N = 1.479(9) and C—O (mean) = 1.25(2) Å.
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  • 54
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    Journal of chemical crystallography 29 (1999), S. 891-899 
    ISSN: 1572-8854
    Keywords: cyclohexaphosphates ; organometallic compound ; crystal growth ; X-ray diffraction ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Three new cyclohexaphosphates with general formula M0.5((C6H5CH2)2NH2)5P6O18·H2O (M=Co, Cu, Cd) are reported. They crystallize with monoclinic unit-cells and are isotropic. We have determined their structure from the salt M=Co. This later exhibits the following unit-cell parameters: a = 22.739(5), b = 17.682(3), c = 18.342(3) Å, β = 91.22(1)°, Z = 4,P21/n, V = 7373 Å3, and Dx = 1.373 g cm−3. The atomic arrangement can be described as layers containing P6O18 ring anions and CoO6 octahedra spreading in the (101) planes and intercalated by the dibenzylammonium groups and the water molecules. Synthesis and characterization by X-ray diffraction, IR absorption, and TA are described.
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  • 55
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    Journal of chemical crystallography 29 (1999), S. 1107-1110 
    ISSN: 1572-8854
    Keywords: crystal structure ; ytterbium ; lanthanide ; coordination complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The preparation and structural characterization of [YbI2(DME)2] are reported. The complex crystallizes in the triclinic space group P 1¯: a = 13.0094 (10), b=14.504(3), c = 14.668 (3) Å, α = 115.281(10) β = 106.74(2), γ = 105.97(2)°. The metal center of the complex exhibits a distorted pentagonal bipyramidal coordination geometry which involves a rare example of a monodentate DME ligand.
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  • 56
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    Journal of chemical crystallography 29 (1999), S. 1127-1132 
    ISSN: 1572-8854
    Keywords: crystal structure ; phenyl-substituted cyclopentenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structures of two stereoisomers of tetraphenyl- and pentaphenyl-substituted cyclopentenes 1 and 2 have been determined by X-ray analysis. An envelope conformation 1E has been ascertained for the cis isomer 1a, whereas the cis, cis isomer 2a, which crystallizes in two different space groups, P1¯ and P21/n, displays a twisted 2T1 conformation. The phenyl substituents are all tilted with respect to the cyclopentene ring in both structures. Compound 1a crystallizes in the space group P21/a with a = 18.553(3), b = 6.006(2), c = 19.355(5), β = 102.67(4)°, and V = 2104.2(g) Å3 for Z = 4; compound 2a I crystallizes in P21/n with a = 10.064(2), b = 20.756(5), c = 12.245(3) Å, β = 95.21(2)°, and V = 2547(1) Å3 for Z = 4; compound 2aII crystallizes in P1¯ with a = 10.117(3), b = 11.750(2), c = 12.359(2) Å, α = 111.25(2), β = 94.84(2), γ = 108.78(2)°, and V = 1262.3(6) Å3 for Z = 2.
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  • 57
    ISSN: 1572-8854
    Keywords: copper (II) ; histamine ; self-assembly ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A new monomeric copper (II) complex with histamine (him), [Cu(II)(him)2(No3)2], has been prepared by the reaction of Cu(NO3)2 with histaminium dichloride and its structure was determined by x-ray crystallography. The complex crystallizes in the triclinic system, space group $$P\bar 1$$ with a = 5.7238(4), b = 8.7094(7), c = 9.2481(11) Å, α = 69.693(8), β = 73.242(7), γ = 71.050(7)°, V = 400.84(6) Å3, and Z = 1. The structure consists of discrete [Cu(II)(him)2(NO3)2] molecules in which the metal atom is centrosymmetrically coordinated by two histamine ligands forming an equatorial plane with Cu–N(imidazole ring) being 2.032(2) and Cu–N(NH2 group) being 2.023(2) Å. Two O atoms from nitrate anions coordinate on the elongated axial positions with Cu–O being 2.549(2) Å. In the crystal structure, the molecules are organized by hydrogen bonds forming a two-dimensional network.
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  • 58
    ISSN: 1572-8854
    Keywords: xanthenol ; complex ; crystal structure ; H-bonding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound 14-hydroxy-14-phenyldibenzo[a,j]xanthene 1 formed a (1:1) complex with diethyl ether. 1,4-Dioxane was also enclathrated, but with a variable stoichiometric ratio. Single crystal X-ray crystallography was used to elucidate the crystal structure of the 1·diethyl ether complex. Crystals are orthorhombic with space group P212121, a = 8.532(3), b = 15.040(4), c = 18.491(5) Å, V = 2373(1) Å3, d c = 1.256 g/cm3, and Z = 4. Host and guest molecules were found to associate via hydrogen bonds, with the guest molecules residing in undulating channels lined by host molecules.
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  • 59
    ISSN: 1572-8854
    Keywords: copper(II) ; Schiff base ; polymidazole ; crystal structure ; properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The square-planar complex [Cu(MIMH)(CH3CO2)](ClO4) (1) (MIMH = [(4-methylimidazol-5-yl)methylene]histamine) was prepared and structurally characterized. Complex 1 crystallizes in the monoclinic space group P21/n with a = 10.5331(10), b = 12.6177(10), c = 12.9773(10) Å, β = 107.710(10)°, V = 1643.0(2) Å3, and Z = 4. Single-crystal X-ray analysis reveals that the copper(II) atom in 1 has a distorted square-planar environment defined by three nitrogen atoms from the Schiff base ligand and one oxygen atom from the acetate group. The Cu—N bond lengths range from 1.950(3) to 2.015(3) Å and the Cu—O(1) bond length is 1.952(2) Å. The electronic spectra of 1 in aqueous solutions indicates that 1 forms adducts of square-pyramidal geometry with H2O. Cyclic voltammetry of 1 in DMF solution shows that there is some degradation of 1 upon reduction.
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  • 60
    ISSN: 1572-8854
    Keywords: pyrazolyl derivative ; substituted pentane ; crystal structure ; bidentate ligand
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallizes in the centrosymmetric space group C2/c with a = 14.4005(23), b = 7.0494(12), c = 11.2462(20) Å, β = 101.572(13)° and Z = 4; the molecule lies on a crystallographic C 2 axis. Hydrogen atoms were both located and refined.
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  • 61
    ISSN: 1572-8854
    Keywords: crystal structure ; Frentizole ; immunomodulator ; structure-function relationship
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Crystals of Frentizole (from ethanol/water) are monoclinic, space group P21/c, with a = 11.187(4), b = 7.392(2), c = 32.727(6) Å, β = 92.77(2)°, Z = 8, D o = 1.47 g/cm3, and D c = 1.472 g/cm3. There are two independent molecules in the crystallographic asymmetric unit with very different conformations. In molecule A the urea group is in the plane of the benzothiazole ring (0.9°) whereas in molecule B the dihedral angle between them is 4.4°. The dihedral angle between the planes of the phenyl group and the benzothiazole ring are ±157° and ±12°, respectively, in the two molecules. The molecules are linked by a pair of N–H···N hydrogen bonds involving the urea nitrogen and two other N–H···N bonds involving the urea nitrogen and the nitrogen of the benzothiazole group.
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  • 62
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    Journal of chemical crystallography 29 (1999), S. 355-358 
    ISSN: 1572-8854
    Keywords: Quinestrol ; sex steroid ; alkyne ; crystal structure ; solvent inclusion ; hydrogen bonding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The X-ray crystal structure of the synthetic sex steroid quinestrol (3-O-cyclopentyl-17α-ethynylestradiol) as crystallized from ethanolic solution is determined. The asymmetric unit contains two steroid and one ethanol molecules. The conformation of the two steroid molecules differs in the orientation of the cyclopentane ring. The cocrystallized ethanol molecule facilitates formation of cooperative O—H···O hydrogen bonding. The title compound crystallizes in the monoclinic space group P21, with a = 13.950(6), b = 6.5945(8), c = 25.403(8) Å, β = 104.78(4)°, and D calc = 1.136 g cm−1 for Z = 4.
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  • 63
    ISSN: 1572-8862
    Keywords: Cluster core M6E8 ; structural characteristics ; crystal structure ; hexacobalt cluster complex ; phosphine ; sulfide bridging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Two new members of the hexanuclear series [Co6S8(PR3)6] n+, complexes [Co6S8(PMe2Ph)6](ClO4) (1) and [Co6S8P(OMe)3 6] (2), have been synthesizes and characterized by X-ray diffraction analyses. Their formation process was postulated to go through trinuclear μ3--S bridged moieties. The structural characteristics of the M6E8P6 skeleton of a whole series of [M6E8(PR3)6] n+ (M=Co, Cr, Fe, Mo; E=S, Se, Te) complexes are presented in terms of atomic distances and core volumes.
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  • 64
    ISSN: 1572-8773
    Keywords: cadmium ; apoptosis ; RT-PCR ; p53 gene expression ; testes ; rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Reverse transcription (RT) PCR technique was used to investigate the mechanism of apoptosis induced by Cd and the change of its related genes in testes and prostate of rats. Adult male rats were given a single (s.c.) injection of CdC l2 0, 2.5, 5.0, 10 μmol/kg. 48 h and 72 h after administration of Cd, animals were sacrificed. The results indicated that Cd can induce apoptosis in testes via p53-independent pathway. No apoptosis occurred in prostate in any of the Cd-exposed groups. There was a clearly negative relationship in testes between p53 gene expression and Cd exposure and this dose-response relationship was observed both at 48 h and 72 h. There was a very small increase of this gene expression in the dorsolateral lobe of the prostate in Cd exposed groups. The other apoptosis related gene, bcl-x, was not detectable in either control or Cd-exposed group in testes and dorsal prostate. Although the MT-I gene was expressed in testes or dorsal prostate both in control and exposed groups, no overexpression of MT-I gene was found after administration of Cd . The expression of MT-I in the ventral prostate was not detected in the control group, but a weak expression was found after Cd exposure. Since p53 is a tumo r suppressor gene which can inhibit tumorigenesis, the consequence of a Cd-induced decrease of p53 in testes may have a relation to the known risk of Cd tumorigenesis in this tissue.
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  • 65
    ISSN: 1432-0789
    Keywords: Key words Phosphorus dynamics ; Olsen ; phosphorus ; Soil phosphorus fractions ; Manure ; Soybean-wheat rotation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Soil P availability and efficiency of applied P may be improved through an understanding of soil P dynamics in relation to management practices in a cropping system. Our objectives in this study were to evaluate changes in plant-available (Olsen) P and in different inorganic P (Pi) and organic P (P0) fractions in soil as related to repeated additions of manure and fertilizer P under a soybean-wheat rotation. A field experiment on a Typic Haplustert was conducted from 1992 to 1995 wherein the annual treatments included four rates of fertilizer P (0, 11, 22 and 44 kg ha–1 applied to both soybean and wheat) in the absence and presence of 16 t ha–1 of manure (applied to soybean only). With regular application of fertilizer P to each crop the level of Olsen P increased significantly and linearly through the years in both manured and unmanured plots. The mean P balance required to raise Olsen P by 1 mg kg–1 was 17.9 kg ha–1 of fertilizer P in unmanured plots and 5.6 kg ha–1 of manure plus fertilizer P in manured plots. The relative sizes of labile [NaHCO3-extractable Pi (NaHCO3-Pi) and NaHCO3-extractable P0 (NaHCO3-P0)], moderately labile [NaOH-extractable Pi (NaOH-Pi) and NaOH-extractable P0 (NaOH-P0)] and stable [HCl-extractable P (HCl-P) and H2SO4/H2O2-extractable P (resisual-P)] P pools were in a 1 : 2.9 : 7.6 ratio. Application of fertilizer P and manure significantly increased NaHCO3-Pi and -P0 and NaOH-Pi, and -P0 fractions and also total P. However, HCl-P and residual-P were not affected. The changes in NaHCO3-Pi, NaOH-Pi and NaOH-P0 fractions were significantly correlated with the apparent P balance and were thought to represent biologically dynamic soil P and act as major sources and sinks of plant-available P.
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  • 66
    ISSN: 1573-0417
    Keywords: carbon isotopes ; diatoms ; lake management ; nitrogen isotopes ; phosphorus ; radium-226 ; sediments ; trophic state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract We explored the use of carbon and nitrogen isotopes (δ13C and δ15N) in sedimented organic matter (OM) as proxy indicators of trophic state change in Florida lakes. Stable isotope data from four 210Pb-dated sediment cores were compared stratigraphically with established proxies for historical trophic state (diatom-inferred limnetic total phosphorus, sediment C/N ratio) and indicators of cultural disturbance (sediment total P and 226Ra activity). Diatom-based limnetic total P inferences indicate a transition from oligo-mesotrophy to meso-eutrophy in Clear Lake, and from eutrophy to hypereutrophy in Lakes Parker, Hollingsworth and Griffin. In cores from all four lakes, the carbon isotopic signature of accumulated OM generally tracks trophic state inferences and cultural impact assessments based on other variables. Oldest sediments in the records yield lower diatom-inferred total limnetic P concentrations and display relatively low δ13C values. In the Clear, Hollingsworth and Parker records, diatom-inferred nutrient concentrations increase after ca. AD 1900, and are associated stratigraphically with higher δ13C values in sediment OM. In the Lake Griffin core, both proxies display slight increases before ~1900, but highest values occur over the last ~100 years. As Lakes Clear, Hollingsworth and Parker became increasingly nutrient-enriched over the past century, the δ15N of sedimented organic matter decreased. This reflects, in part, the increasing relative contribution of nitrogen-fixing cyanobacteria to sedimented organic matter as primary productivity increased in these waterbodies. The Lake Griffin core displays a narrow range of both δ13C and δ15N values. Despite the complexity of carbon and nitrogen cycles in lakes, stratigraphic agreement between diatom-inferred changes in limnetic total P and the stable isotope signatures of sedimented OM suggests that δ13C and δ15N reflect shifts in historic lake trophic state.
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  • 67
    ISSN: 1573-0417
    Keywords: diatoms ; Everglades ; phosphorus ; wetland ; calibration ; multivariate ; Florida
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The relationship between diatom taxa preserved in surface soils and environmental variables at 31 sites in Water Conservation Area 2A (WCA-2A) of the Florida Everglades was explored using multivariate analyses. Surface soils were collected along a phosphorus (P) gradient and analyzed for diatoms, total P, % nitrogen (N), %carbon (C), calcium (Ca), and biogenic silica (BSi). Phosphorus varied from 315-1781 μg g-1, and was not found to be correlated with the other geochemical variables. Canonical correspondence analysis (CCA) was used to examine which environmental variables correlated most closely with the distributions in diatom taxa. Canonical correspondence analysis with forward selection, constrained and partial CCA, and Monte Carlo permutation tests of significance show the most significant changes in diatom assemblages along the P gradient (p 〈 0.01), with additional species differences correlated with soil C, N, Ca, and BSi. Weighted-averaging (WA) regression and calibration models of diatom assemblages to P and BSi were developed. The diatom-based inference model for soil [P] had a high apparent r2 (0.86) with RMSEboot = 218 μg g-1. Indicator diatom species identified by assessing species WA optima and WA tolerance to [P], such as Nitzschia amphibia and N. palea for high [P] (~1300-1400 μ g-1) and Achnanthes minutissima var. scotica and Mastogloia smithii for low [P] (~400-600 μg g-1), may be useful as monitoring tools for eutrophication in WCA-2A as well as other areas of the Everglades. Diatom assemblages analyzed by cluster analysis were related to location within WCA-2A, and dominant taxa within clusters are discussed in relation to the geochemical variables measured as well as hydrology and pH. Diversity of diatom assemblages and a ‘Disturbance Index’ based on diatom data are discussed in relation to the historically P-limited Everglades ecosystem. Diatom assemblages should be very useful for reconstructions of [P] through time in the Florida Everglades, provided diatoms are well preserved in soil cores.
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  • 68
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    Nutrient cycling in agroecosystems 55 (1999), S. 7-14 
    ISSN: 1573-0867
    Keywords: fertiliser formulation ; nutrients ; phosphorus ; relative humidity ; soil moisture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphorus lost in runoff from agricultural land leads to the enrichment of surface waters and contributes to algal blooms. Fertilisers are one source of this P. To compare the water available P of different fertiliser formulations in the laboratory it is necessary to control environmental conditions, temperature, relative humidity and soil water content, prior to simulating rainfall. Two chambers were designed in which relative humidity and soil water content were controlled using salt solutions. An initial design comprising a sealed chamber with three layers of soil samples over a salt bath was found to be inferior to a single layer design. The changes in water content of soil samples were used to test the single layer chamber in a constant temperature environment (15 °C) using a saturated KCl solution (90% relative humidity). Based on the final soil water content of the samples, the spatial variation within the chamber was within tolerable limits. The single layer chamber was used for a simulation experiment comparing the water available P of two commercial fertilisers. Using a saturated resorcinol solution (95% relative humidity) soil samples were equilibrated at 15 °C for 21 days, fertiliser added, and the water available P measured up to 600 h after fertiliser application. The results indicate that the amount of water available P was related to the fertiliser compound and exponentially related to the time since fertiliser application. It was concluded that the single layer chamber is suitable for controlling relative humidity and soil water content in trials such as these where the water available P of fertilisers are being compared.
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  • 69
    ISSN: 1573-0867
    Keywords: dairy systems ; feeds ; fertilizers ; phosphorus ; P surplus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Inputs of phosphorus (P) above requirements for production on dairy farms lead to surplus P with increased risk of P transfer in land run-off to surface waters causing eutrophication. The impact of reducing surplus P inputs in purchased feeds and fertilizers on milk and forage production was investigated in a comparison of three dairy farm systems on chalkland soils in southern England over a 3-year period. In accordance with current commercial practice, no attempt was made to regulate P inputs in system 1, which accumulated an average annual surplus of 23 kg P ha-1. Progressive reductions in purchased feed and/or fertilizer inputs into systems 2 and 3 decreased surplus P to 17 and 3 kg ha-1, respectively, without apparently limiting either milk or herbage dry matter production. The estimated reduction in faecal P output from system 3 cows fed a low P diet compared to system 1 cows fed a high P diet was 26%. Milk P concentrations significantly (P 〈0.001) increased in systems 2 and 3 which included maize in the diet. Output of P in milk and meat products, as a proportion of the total dietary P inputs, increased from 28% in system 1 to 36% in system 3. Surplus P was greatest in continuous maize fields receiving both dairy manure and starter P fertilizer. Withholding P fertilizer in system 3 did not reduce P offtake in cut herbage on soils of moderate P fertility. Total annual losses of P in storm run-off and leaching were no greater than annual inputs of P from the atmosphere (0.5 kg ha-1). The results indicate there is scope to reduce surplus P on commercial dairy farms without sacrificing production targets at least in the short term. Purchased feeds are the largest of the P inputs on intensive dairy farms, yet these are rarely quantified on commercial holdings.
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  • 70
    ISSN: 1573-0867
    Keywords: leaching ; phosphorus ; poultry litter ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To determine P loadings, added through poultry litter, sufficient to cause downward movement of P from the cultivated layer of a sandy soil, six rates of poultry litter were applied annually for four years to a site in central England. (total loading 0 – 1119 kg P ha-1). A single extra plot also received an extra 1000 kg ha-1 as triple superphosphate (TSP; total loading 2119 kg P ha-1) and three other treatments received 200 – 800 kg ha-1 P as TSP only. Annual soil sampling in 30-cm increments to 1.5-m depth provided information on P build-up in the topsoil and P movement to depth. There were strong linear trends between P balance (P applied – P removed in crops) and total P, Olsen bicarbonate extractable P and water-soluble P in the topsoil. Phosphorus from TSP and poultry litter fell on the same regression lines, suggesting that both would be equally effective as fertilizer sources. We calculated that 100 kg ha-1 surplus total P would increase the Olsen extractable P content by c. 6 mg kg-1 and the water-soluble P by c. 5 mg kg-1. Thus, relatively large amounts of P would need to be applied to raise soil P status. We found some evidence of P movement into the soil layers immediately below cultivation depth. However, neither soil sampling nor soil solution extracted through Teflon water samplers showed evidence of movement into the deep subsoil (1 m) despite large P loadings.
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  • 71
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    Nutrient cycling in agroecosystems 54 (1999), S. 259-266 
    ISSN: 1573-0867
    Keywords: bahiagrass ; manure ; pasture fertilization ; phosphorus ; phosphorus cycling ; Spodosol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Bahiagrass (Paspalum notatum Flugge) pasture fertilization recommendations have traditionally been based upon clipping studies. Inclusion of P from manure, not originally considered when P recommendations were developed for pastures, may minimize the need for P fertilization without reducing bahiagrass production or P uptake. The objective of this research was to determine if manure contributes greatly to the P crop nutrient requirement. A 2-year field study utilized a factorial arrangement of 0 and 6.9 Mg air-dried manure ha-1 with 0, 17, 34, 51, and 68 kg inorganic P ha-1 from triple superphosphate to evaluate bahiagrass yield, root distribution, and P uptake response on a Myakka fine sand (sandy, siliceous, hyperthermic Aeric Alaquod). Because air-dried manure was used in the field study, a greenhouse study was employed to confirm that there were no differences in bahiagrass yield or P uptake from either air-dried or fresh cattle (Bos spp.) manure sources. There were no manure or manure by P interaction effects on yield or P uptake of bahiagrass indicating that manure source did not effect grass production in the greenhouse. In the field study, bahiagrass roots were distributed into the Bh horizon, and the Bh horizon had at least four times more Mehlich-1 extractable P than that of the Ap horizon. This horizon was most likely acting as a main source for P-uptake by the grass. This observation was further confirmed by no yield response to levels of inorganic P application in 1989. A linear-response-and-plateau (R2=0.196) relationship with a critical point of 15.4 kg P ha-1 was found in 1990. Bahiagrass yield and P uptake were not dependent on P fertilization, either from manure or inorganic P, due to the availability of P from the Bh horizon.
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  • 72
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    Journal of thermal analysis and calorimetry 55 (1999), S. 797-806 
    ISSN: 1572-8943
    Keywords: cadmium coordination ; crystal structure ; enthalpy of solution ; lattice energy ; lattice enthalpy ; NTO salt ; preparation ; standard enthalpy of dehydration ; standard enthalpy of formation ; thermal decomposition mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract [Cd(NTO)4Cd(H2O)6]·4H2O was prepared by mixing the aqueous solution of 3-nitro-1,2,4-triazol-5-one and cadmium carbonate in excess. The single crystal structure was determined by a four-circle X-ray diffractometer. The crystal is monoclinic, space group C2/c with crystal parameters of a=2.1229(3) nm, b=0.6261(8) nm, c=2.1165(3) nm, β=90.602(7)°, V=2.977(6) nm3, Z=4, Dc=2.055 g·cm−3, μ=15.45 cm−1, F(000)=1824, λ(MoKα)=0.071073 nm. The final R is 0.0282. Based on the results of thermal analysis, the thermal decomposition mechanism of [Cd(NTO)4Cd(H2O)6]·4H2O was derived. From measurements of the enthalpy of solution of [Cd(NTO)4Cd(H2O)6]·4H2O in water at 298.15 K, the standard enthalpy of formation, lattice energy, lattice enthalpy and standard enthalpy of dehydration have been determined as -(1747.8±4.8), -2394, -2414 and 313.6 kJ mol−1 respectively.
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  • 73
    ISSN: 1572-9001
    Keywords: Tetrahydrotetrol ; polycyclic aromatic hydrocarbon derivative ; carcinogen ; crystal structure ; structure-activity relationship
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The molecular structures of two racemic trans-tetrahydrotetrols formed by hydrolysis of the (±)anti-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydro derivatives of the strong carcinogen benzo[a]pyrene and the weak carcinogen chrysene have been determined by X-ray crystallographic methods.3 Focusing on the (+)isomers, the stereochemical features of the two tetrols are discussed in detail to determine structural differences, which can be related to the different biological activity of their parent hydrocarbons, since they provide a model for the hydrocarbon moiety in the major PAH-DNA adduct. As a result of this study, a tentative correlation can be stated between biological activity of quasi-planar bay-region PAHs and the presence of structural features, which can decrease the steric hindrance of the aromatic skeleton and the other hydroxy groups on the pseudo-axial O4, which mimics the position of the covalent bond to DNA. The significant structural features seem to be an out-of-plane distortion with a negative torsion angle at the bay region and a half chair conformation of the saturated ring distorted toward the envelope with C8 at the tip as in BPT, in addition to the axial and pseudo-axial conformations of the hydroxy groups at C9 and C10 due to the near bay region. They may be considered generated by trans-opening of the oxirane ring in an anti-diol epoxide biologically active because it is highly strained. The strains, derived from the activation of bay-region PAHs with a negative torsion angle, seem greater in an anti-diol epoxide relative to the syn-isomer. Thus, when the strains are released, the derived trans-tetrol occurs with structural features, which seem to better fit the target. As a consequence, the presence of a methyl group at a bay region should increase the biological activity of a PAH, imposing greater strains to the structure of the anti-diol epoxide.
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  • 74
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    Journal of thermal analysis and calorimetry 57 (1999), S. 807-821 
    ISSN: 1572-8943
    Keywords: bibliography ; critical temperature ; crystal structure ; CuRh2S4 ; CuRh2Se4 ; survey of chalcogenide superconductors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The thread that runs through all research in the field of superconductivity is new physics through discovery of new materials. The knowledge of superconducting materials has become voluminous and complex. The comprehensive review of the superconducting materials is of particular importance. The main purpose of this report is to present the results of classification for chalcogenide superconductors. Superconducting critical temperature Tc, crystal-structure type and the references proper to these compounds are summarized. Brief survey of the superconductivity in chalcogen elements is also given. Furthermore, as representative sulfide and selenide, superconducting characteristics of CuRh2S4 and CuRh2Se4 will be shown.
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  • 75
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    Journal of thermal analysis and calorimetry 58 (1999), S. 257-267 
    ISSN: 1572-8943
    Keywords: crystal structure ; lattice energy ; lattice enthalpy ; lead salt of NTO ; preparation ; quantum chemical calculation ; thermal decomposition mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The single crystal of lead salt of 3-nitro-1,2,4-triazol-5-one (NTO), [Pb(NTO)2(H2O)] was prepared and its structure was determined by a four-circle X-ray diffractometer. The crystal is monoclinic, its space group is P21/n with crystal parameters of a=0.7262(1) nm, b=1.2129(2) nm, c=1.2268(3) nm, β=90.38(2)°, V=1.0806(2) nm3, Z=4, Dc=2.97 g cm−3, µ=157.83cm−1, F(000)=888. The final R is 0.027. By using SCF-PM3-MO method we obtained optimized geometry for [Pb(NTO)2⋅H2O] and particularly positions for hydrogen atoms. Through the analyses of MO levels and bond orders it is found that Pb atom bond to ligands mainly with its 6pz and 6py AOs. The thermal decomposition experiments are elucidated when [Pb(NTO)2⋅H2O] is heated, ligand water is dissociated first and NO2 group has priority of leaving. Based on the thermal analysis, the thermal decomposition mechanism of [Pb(NTO)2⋅H2O] has been derived. The lattice enthalpy and its lattice energy were also estimated.
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  • 76
    ISSN: 1572-9001
    Keywords: Nickel complex ; dithiocarbimate ; sulfonamide ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Potassium N-4-methylphenylsulfonyldithiocarbimate, K2(4-CH3C6H4SO2N=CS2), reacted with nickel(II) chloride hexahydrate and tetrabutylammonium bromide to form the bis(N-4-methylphenylsulfonyldithiocarbimate)nickelate(II) tetrabutylammonium salt (Bu4N)2[Ni(4-CH3C6H4S2C=NSO2)2]. The elemental analyses, IR and UV-Vis data obtained were consistent with the formation of a $${\text{nickel}}{\kern 1pt} - {\kern 1pt} {\text{sulfur}}$$ diamagnetic planar complex. The 1H NMR and the 13C NMR spectra showed the expected signals for the dithiocarbimate moiety and the tetrabutylammonium cation. The single-crystal structure analysis showed that this substance crystallizes in the triclinic $${P\bar 1}$$ space group with a = 10.474(3) Å, b = 10.767(3) Å, c = 13.657(3) Å and α = 81.54(2)°, β = 80.44(2)°, γ = 67.63(2)°, V = 1398.5(8) Å3, and Z = 2. The nickel atom is coordinated to four sulfur atoms.
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  • 77
    ISSN: 1572-9001
    Keywords: Nicotine-derived nitrosaminoketone ; nitrosamine ; crystal structure ; molecular dimensions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The three-dimensional structure of the carcinogenic nicotine-derived nitrosaminoketone, 4-(methyl-nitrosamino)-l-(3-pyridyl)-l-butanone, has been determined by X-ray crystallographic techniques. The molecule is essentially planar except for the methylnitrosamine group which is oriented at a dihedral angle of 68.7° to the pyridine ring. Molecules pack by way of —H⋯O interactions that involve the —NNO group.
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  • 78
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    Molecular and cellular biochemistry 196 (1999), S. 13-21 
    ISSN: 1573-4919
    Keywords: apoptosis ; DNA fragmentation ; GSHPx-1 knockout mice ; GSHPx-1 transgenic mice ; ischemia/repurfusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Apoptosis, a genetically controlled programmed cell death, has been found to play a role in ischemic reperfusion injury in several animal species including rats and rabbits. To examine whether this is also true for other animals, an isolated perfused mouse heart was subjected to 30 min of ischemia followed by 2 h of reperfusion. Experiments were terminated before ischemia (baseline), after ischemia, and at 30, 60, 90 and 120 min of reperfusion. At the end of each experiment, hearts were processed for the evaluation of apoptosis and DNA laddering. The in situ end labeling (ISEL) technique was used to detect apoptotic cardiomyocyte nuclei while DNA laddering was evaluated by subjecting the DNA obtained from the cardiomyocytes to 1.8% agarose gel electrophoresis followed by photographing under UV illumination. The results of our study revealed that apoptotic cells appear only after 60 min of reperfusion as demonstrated by the intense fluorescence of the immunostained genomic DNA when observed under fluorescence microscopy. None of the ischemic hearts showed any evidence of apoptosis. These results were corroborated with the findings of DNA fragmentation showing increased ladders of DNA bands in the same reperfused hearts representing integer multiples of the internucleosomal DNA length (about 180 bp). Since our previous studies showed a role of glutathione peroxidase (GSHPx) in apoptotic cell death, we performed identical experiments using isolated hearts from GSHPx-l knockout mice and transgenic mice overexpressing GSHPx-l. GSHPx-l knockout mice showed evidence of apoptotic cell death even after 30 min of reperfusion. Significant number of apoptotic cells were found in the cardiomyocytes as compared to non-transgenic control animals. To the contrary, very few apoptotic cells were found in the hearts of the transgenic mice overexpressing GSHPx-l. Hearts of GSHPx-l knockout mice were more susceptible to ischemia/reperfusion injury while transgenic mice overexpressing GSHPx- 1 were less susceptible to ischemia reperfusion injury compared to non-transgenic control animals. The results of this study clearly demonstrate a role of GSHPx in ischemia/reperfusion-induced apoptosis in mouse heart.
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  • 79
    ISSN: 1573-4919
    Keywords: MKP-1 ; Fas ligand ; Fas ; apoptosis ; prostate cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Recent studies have suggested that MAP kinase phosphatase 1 (MKP-1) is overexpressed in prostate cancer. To evaluate the role of MKP-1 in regulating cell death and tumor growth in prostate cancer, MKP-1 was conditionally overexpressed in the human prostate cancer cell line DU145. Overexpression of MKP-1 in DU145 cells blocked activation of stress-activated protein kinase (SAPK/JNK). MKP-1 overexpression in DU-145 cells was also found to inhibit Fas ligand (FasL)-induced apoptosis, as well as block the activation of caspases by Fas engagement. In addition, MKP-1 blocked the activation of apoptosis by transfected MEKK-1 and ASK-1, presumably through its inhibition of the SAPK/JNK family of enzymes. MKP-1 blocked the ability of FasL to induce loss of mitochondrial transmembrane potential (Δγm), suggesting that MKP-1 acts upstream of mitochondrial pro-apoptotic events induced by FasL and that the SAPK/JNK pathway may form the signaling link between Fas receptor and mitochondrial dysfunction. Thus, MKP-1 overexpression in prostate cancer may play a role in promoting prostate carcinogenesis by inhibiting FasL-induced cell death.
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  • 80
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    Molecular and cellular biochemistry 199 (1999), S. 125-137 
    ISSN: 1573-4919
    Keywords: apoptosis ; ADP-ribosylation ; caspases ; PARP ; PARG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Poly(ADP-ribosylation) is a post-translational modification playing a relevant role in DNA damage recovery, DNA replication and viral integration. Several reports also suggest a modulation of this process during cell death by apoptosis. The aim of this review is to discuss the possible involvement of poly(ADP-ribosylation) during apoptosis, by dealing with general considerations on apoptosis, and further examining the correlation between NAD consumption and cell death, the regulation of poly(ADP-ribose) metabolism in apoptotic cells, the effect of poly(ADP-ribose) polymerase inhibition on cell death occurrence and the use of enzyme cleavage as a marker of apoptosis. Finally, the future prospects of the research in this area will be addressed.
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  • 81
    ISSN: 1573-4919
    Keywords: DNA binding protein ; NAD metabolism ; cellular response to DNA damage ; γ-rays ; alkylating agents ; genomic instability ; apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract A dual approach to the study of poly (ADP-ribose)polymerase (PARP) in terms of its structure and function has been developed in our laboratory. Random mutagenesis of the DNA binding domain and catalytic domain of the human PARP, has allowed us to identify residues that are crucial for its enzymatic activity. In parallel PARP knock-out mice were generated by inactivation of both alleles by gene targeting. We showed that: (i) they are exquisitely sensitive to γ-irradiation, (ii) they died rapidly from acute radiation toxicity to the small intestine, (iii) they displayed a high genomic instability to γ-irradiation and MNU injection and, (iv) bone marrow cells rapidly underwent apoptosis following MNU treatment, demonstrating that PARP is a survival factor playing an essential and positive role during DNA damage recovery and survival.
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  • 82
    ISSN: 1573-4919
    Keywords: PARP ; poly(ADP-ribosyl)ation ; apoptosis ; DNA replication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract We have focused on the roles of PARP and poly(ADP-ribosyl)ation early in apoptosis, as well as during the early stages of differentiation-linked DNA replication. In both nuclear processes, a transient burst of PAR synthesis and PARP expression occurs early, prior to internucleosomal DNA cleavage before commitment to apoptosis as well as at the round of DNA replication prior to the onset of terminal differentiation. In intact human osteosarcoma cells undergoing spontaneous apoptosis, both PARP and PAR decreased after this early peak, concomitant with the inactivation and cleavage of PARP by caspase-3 and the onset of substantial DNA and nuclear fragmentation. Whereas 3T3-L1, osteosarcoma cells, and immortalized PARP +/+ fibroblasts exhibited this early burst of PAR synthesis during Fas-mediated apoptosis, neither PARP-depleted 3T3-L1 PARP-antisense cells nor PARP -/- fibroblasts showed this response. Consequently, whereas control cells progressed into apoptosis, as indicated by induction of caspase-3-like PARP-cleavage activity, PARP-antisense cells and PARP -/- fibroblasts did not, indicating a requirement for PARP and poly(ADP-ribosyl)ation of nuclear proteins at an early reversible stage of apoptosis. In parallel experiments, a transient increase in PARP expression and activity were also noted in 3T3-L1 preadipocytes 24 h after induction of differentiation, a stage at which ~95% of the cells were in S-phase, but not in PARP-depleted antisense cells, which were consequently unable to complete the round of DNA replication required for differentiation. PARP, a component of the multiprotein DNA replication complex (MRC) that catalyzes viral DNA replication in vitro, poly(ADP-ribosyl)ates 15 of ~40 MRC proteins, including DNA pol α, DNA topo I, and PCNA. Depletion of endogenous PARP by antisense RNA expression in 3T3-L1 cells results in MRCs devoid of any DNA pol α and DNA pol δ activities. Surprisingly, there was no new expression of PCNA and DNA pol α, as well as the transcription factor E2F-1 in PARP-antisense cells during entry into S-phase, suggesting that PARP may play a role in the expression of these proteins, perhaps by interacting with a site in the promoters for these genes.
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  • 83
    ISSN: 1573-4919
    Keywords: breast cancer cells ; anti-apoptotic genes ; apoptosis ; progesterone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Progesterone inhibits the proliferation of normal breast epithelial cells in vivo, as well as breast cancer cells in vitro. But the biologic mechanism of this inhibition remains to be determined. We explored the possibility that an antiproliferative activity of progesterone in breast cancer cell lines is due to its ability to induce apoptosis. Since p53, bcl-2 and survivin genetically control the apoptotic process, we investigated whether or not these genes could be involved in the progesterone-induced apoptosis. We found a maximal 90% inhibition of cell proliferation with T47-D breast cancer cells after exposure to 10 μM progesterone for 72 h. Control progesterone receptor negative MDA-231 cancer cells were unresponsive to 10 μM progesterone. The earliest sign of apoptosis is translocation of phosphatidylserine from the inner to the outer leaflet of the plasma membrane and can be monitored by the calcium-dependent binding of annexin V in conjunction with flow cytometry. After 24 h of exposure to 10 μM progesterone, cytofluorometric analysis of T47-D breast cancer cells indicated 43% were annexin V-positive and had undergone apoptosis and no cells showed signs of cellular necrosis (propidium iodide negative). After 72 h of exposure to 10 μM progesterone, 48% of the cells had undergone apoptosis and 40% were annexin V positive/propidium iodide positive indicating signs of necrosis. Control untreated cancer cells did not undergo apoptosis. Evidence proving apoptosis was also demonstrated by fragmentation of nuclear DNA into multiples of oligonucleosomal fragments. After 24 h of exposure of T47-D cells to either 1 or 10 μM progesterone, we observed a marked down-regulation of protooncogene bcl-2 protein and mRNA levels. mRNA levels of survivin and the metastatic variant CD44 v7-v10 were also downregulated. Progesterone increased p53 mRNA levels. These results demonstrate that progesterone at relative high physiological concentrations, but comparable to those seen in plasma during the third trimester of human pregnancy, exhibited a strong antiproliferative effect on breast cancer cells and induced apoptosis.
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  • 84
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    Molecular and cellular biochemistry 200 (1999), S. 51-57 
    ISSN: 1573-4919
    Keywords: smokeless tobacco ; apoptosis ; nitric oxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Smokeless tobacco usage is, a growing public health concern in the United States. Lesions of the oral cavity have been clearly linked to smokeless tobacco use. The objective of this study was to determine the biochemical effects of smokeless tobacco extract (STE) exposure upon hamster cheek pouch cell (HCPC-1) cultures. HCPC-1 cells were exposed to a 5 -fold dose-range of STE (0.5, 1.0 and 2.5%) over a time-course of 24-96 h. Following each exposure we measured various biochemical parameters of cell proliferation and cell death. Cell viability, cell cycle progression and S-phase DNA synthesis were measured as markers of cell proliferation. We measured lactate dehydrogenase leakage as a marker of cell membrane damage and cell death due to necrosis. No significant alterations were observed in cell cycle progression and cell proliferation as a result of exposure to STE. LDH measured colorimetrically indicated no significant effect with the lower doses (0.5, 1.0 and 2.5% STE). Apoptosis measured as the A0 peak and by the TUNEL procedure revealed that STE caused significant rates of apoptosis. Maximal apoptosis was noted between 48-96 h. In order to probe the mechanism further we measured the levels of nitrites as an indicator of nitric oxide (NO) in the media. NO levels were significantly elevated at the doses that caused an induction of apoptosis. The results from this study indicate that STE causes a dose-dependent induction of apoptosis and that this is mediated by nitric oxide.
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  • 85
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    Molecular and cellular biochemistry 193 (1999), S. 37-42 
    ISSN: 1573-4919
    Keywords: Rho ; GTPase ; toxins ; Clostridium ; signal transduction ; apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The Rho family small GTPases are members of the Ras superfamily of small GTPases. Rho proteins were first determined to act as key regulators of many types of actin cytoskeletal-dependent cellular functions. Recent work by several investigators indicates that Rho GTPases are also critical modulators of several important intracellular and nuclear signal transduction pathways. Certain clostridial toxins and exoenzymes covalently modify, and thereby inactivate, specific types of Rho family GTPases. As such, these microbial enzymes have proven invaluable in helping to identify structural and functional attributes of Rho GTPases.
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  • 86
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    Molecular and cellular biochemistry 193 (1999), S. 103-108 
    ISSN: 1573-4919
    Keywords: Poly(ADP-ribose) polymerase ; Drosophila melanogaster ; alternative splicing ; apoptosis ; DNA repair ; development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Poly(ADP-ribose) polymerase (PARP) is conserved in eukaryotes. To analyze the function of PARP, we isolated and characterized the gene for PARP in Drosophila melanogaster. The PARP gene consisted of six translatable exons and spanned more than 50 kb. The DNA binding domain is encoded by exons 1-4. Although the consensus cleavage site of CED-3 like protease during apoptosis is conserved from human to Xenopus laevis PARPs, it is neither conserved in the corresponding region of Drosophila nor Sarcophaga peregrina. There are two cDNAs species in Drosophila. One cDNA could encode the full length PARP protein (PARP I), while the other is a truncated cDNA which could encode a partial-length PARP protein (PARP II), which lacks the automodification domain and is possibly produced by alternative splicing. The expression of these two forms of PARP in E. coli demonstrated that while PARP II has the catalytic NAD-binding domain and DNA-binding domain it is enzymatically inactive. On the other hand PARP I is active. A deletion mutant of PARP gene could grow to the end of embryogenesis but did not grow to the adult fly. These results suggest that the PARP gene plays an important function during the development of Drosophila.
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  • 87
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    Molecular and cellular biochemistry 193 (1999), S. 119-125 
    ISSN: 1573-4919
    Keywords: benzamides ; nicotinamides ; apoptosis ; inflammation ; NF-kB ; DNA repair
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Our laboratory has concentrated on the possible regulation the benzamides and nicotinamides may have on the processes of DNA repair and apoptosis. Recent reports [14-16] have suggested that both apoptosis and inflammation are regulated by the transcription factor NF-kB. We have initiated studies regarding the hypothesis that the benzamides and nicotinamides could inhibit the production of tumor necrosis factor alpha (TNFalpha) and the inflammatory response as well as induce apoptosis via inhibition of NF-kB. Our data have shown that nicotinamide and two N-substituted benzamides, metoclopramide (MCA) and 3-chloroprocainamide (3-CPA), gave dose dependent inhibition of lipopolysacharide induced TNFalpha in the mouse within the dose range of 10-500 mg/kg. Moreover, lung edema was prevented in the rat by 3 ï 50 mg/kg doses of 3-CPA or MCA, and 100-200 μM doses of MCA could also inhibit NF-kB in Hela cells. Taken together these data strongly support the notion that benzamides and nicotinamides have potent anti-inflammatory and antitumor properties, because their primary mechanism of action is regulated by inhibition at the gene transcription level of NF-kB, which in turn inhibits TNFalpha and induces apoptosis.
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  • 88
    ISSN: 1573-4919
    Keywords: antisense oligonucleotide ; apoptosis ; cAMP-dependent protein kinase ; cancer cells ; growth inhibition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The enhanced expression of the RIα subunit of cyclic AMP-dependent protein kinase type 1 (PKA-I) has been correlated with cancer cell growth. We have investigated the effects of sequence-specific inhibition of RIα gene expression on the growth of MCF-7 human breast cancer cells. We report that RIα antisense treatment results in a reduction in RIα expression at both mRNA and protein levels and inhibition of cell growth. The growth inhibition was accompanied by changes in cell morphology, cleavage of poly(ADP-ribose) polymerase (PARP) and appearance of apoptotic nuclei. In addition, bcl-2 protein level was reduced and p53 expression increased in growth arrested cells. Interestingly, RIα antisense inhibited cell viability and induced apoptosis in the absence of p53, suggesting that these actions of RIα antisense are exerted independent of p53. In contrast, two- and four-base mismatched control oligonucleotides had no effect on either cell growth or morphology. These results demonstrate that the RIα antisense, which efficiently depletes the growth stimulatory molecule RIα, induces cell differentiation and apoptosis, providing a new approach to combat breast cancer cell growth.
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  • 89
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    Molecular and cellular biochemistry 197 (1999), S. 97-108 
    ISSN: 1573-4919
    Keywords: neutrophil ; PKC ; TNF-α ; apoptosis ; DNA fragmentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract In the present study we investigated the TNF-α induced signal transduction mechanism in human neutrophil. Exogenously added TNF-α affects both PKC activity and its translocation from cytosol to the membrane. Endogenous protein phosphorylation pattern is inhibited in TNF-α induced neutrophil in Ca-dependent and Ca-independent manner, including a major 47 and 66 kDa cytosolic proteins, which may be implicated in superoxide anion generation. However TNF-α dose dependently enhances the expression of ζ-PKC isotype but not the β-PKC. Morphology and cell cytotoxicity are studied in TNF-α treated neutrophil to understand the TNF-α induced cell death or apoptosis and these experiment is further confirmed by DNA fragmentation analysis. These results clearly demonstrate that TNF-α induces cellular death of human neutrophil at least in part by enhanced expression of Ca-independent ζ-PKC. These observations provide an insight towards understanding the function of ζ-PKC in apoptotic pathway.
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  • 90
    ISSN: 1573-4919
    Keywords: rotenone ; apoptosis ; oncogenes ; liver cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Rotenone decreases the incidence of hepatocellular carcinoma and lowers rates of hepatocellular proliferation. In an effort to delineate mechanisms involved, the in vivo effect of rotenone on liver mitochondrial metabolism, apoptotic machinery as well as elements of the hepatic signal transduction pathways were investigated. Mitochondria from livers of male B6C3F1 mice fed a standard diet containing 600 ppm rotenone for 7 days were uncoupled or inhibited when succinate or glutamate plus malate were used as the substrate, respectively. These livers also showed a significant increase in apoptosis compared with control livers. Furthermore, rotenone increased the expression of c-myc mRNA to 5-fold of control values within 3 days, an effect which was still observed (3-fold) after 7 days. Levels of p53 mRNA were also increased 3-fold after 1 day, but declined to control levels by 7 days. Rotenone also caused a transient, yet marked increase in liver particulate glyceraldehyde phosphate dehydrogenase (GAPDH) protein expression, while it did not alter the expression of the cytosolic form of the enzyme. Conversely, mRNA of the proto-oncogene H-ras showed a decline of 35% after 3 days of rotenone treatment, and remained diminished for the duration of the experiment. These data suggest that rotenone may act as an anticancer agent by diminishing mitochondrial bioenergetics which prevents basal hepatocyte proliferation and lowers the threshold for liver cells with DNA damage to undergo apoptosis.
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  • 91
    ISSN: 1573-4943
    Keywords: Two-dimensional electrophoresis ; MALDI-MS ; apoptosis ; RNA polymerase B transcription factor 3
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Apoptosis or programmed cell death is essential in the process of controlling lymphocyte growth and selection. We identified RNA polymerase B transcription factor 3 (BTF3), which is associated with anti-IgM antibody-mediated apoptosis, using a subclone of the human Burkitt lymphoma cell line BL60. To identify the transcription factor BTF3, which is expressed only in minor amounts, we used preparative high-resolution two-dimensional gel electrophoresis (2DE) employing carrier ampholytes for isoelectric focusing. Comparison of the 2DE protein patterns from apoptotic and nonapoptotic cells showed BTF3 as a predominantly altered protein spot. The characterization of the differentially expressed transcription factor and 13 marker proteins described in this study were performed by internal Edman microsequencing and/or by peptide mass fingerprinting using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The proteome analysis was significantly improved by performing the newly developed preparative high-resolution two-dimensional gels employing high protein concentrations.
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  • 92
    ISSN: 1573-5125
    Keywords: denitrification ; nature restoration ; nitrogen ; phosphorus ; riparian areas ; sedimentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In Denmark, as in many other European countries, the diffuse losses of nitrogen (N) and phosphorus (P) from the rural landscape are the major causes of surface water eutrophication and groundwater pollution. The export of total N and total P from the Gjern river basin amounted to 18.2 kg ha−1 and 0.63 kg P ha−1 during June 1994 to May 1995. Diffuse losses of N and P from agricultural areas were the main nutrient source in the river basin contributing 76% and 51%, respectively, of the total export. Investigations of nutrient cycling in the Gjern river basin have revealed the importance of permanent nutrient sinks (denitrification and overbank sedimentation) and temporary nutrient storage in watercourses. Temporary retention of N and P in the watercourses thus amounted to 7.2–16.1 g N m−2 yr−1 and 3.7–8.3 g P m−2 yr−1 during low-flow periods. Deposition of P on temporarily flooded riparian areas amounted from 0.16 to 6.50 g P m−2 during single irrigation and overbank flood events, whereas denitrification of nitrate amounted on average to 7.96 kg N yr−1 per running metre watercourse in a minerotrophic fen and 1.53 kg N yr−1 per linear metre watercourse in a wet meadow. On average, annual retention of N and P in 18 Danish shallow lakes amounted to 32.5 g N m−2 yr−1 and 0.30 g P m−2 yr−1, respectively, during the period 1989–1995. The results indicate that permanent nutrient sinks and temporary nutrient storage in river systems represent an important component of river basin nutrient budgets. Model estimates of the natural retention potential of the Gjern river basin revealed an increase from 38.8 to 81.4 tonnes yr−1 and that P-retention increased from −0.80 to 0.90 tonnes yr−1 following restoration of the water courses, riparian areas and a shallow lake. Catchment management measures such as nature restoration at the river basin scale can thus help to combat diffuse nutrient pollution.
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  • 93
    ISSN: 1573-5052
    Keywords: mineralization ; nitrogen ; phosphorus ; salinity ; stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plant zonation patterns across New England salt marshes have been investigated for years, but how nutrient availability differs between zones has received little attention. We investigated how N availability, P availability, and plant N status varied across Juncus gerardii, Spartina patens, and mixed forb zones of a Northern New England high salt marsh. We also investigated relationships between several edaphic factors and community production and diversity across the high marsh. P availability, soil salinity, and soil moisture were higher in the mixed forb zone than in the two graminoid zones. NH+ 4-N availability was highest in the J. gerardii zone, but NO− 3-N availability and mid season net N mineralization rates did not vary among zones. Plant tissue N concentrations were highest in the mixed forb zone and lowest in the S. patens zone, reflecting plant physiologies more so than soil N availability. Community production was highest in the J. gerardii zone and was positively correlated with N availability and negatively correlated with soil moisture. Plant species diversity was highest in the mixed forb zone and was positively correlated with P availability and soil salinity. Thus, nutrient availability, plant N status, and plant species diversity varied across zones of this high marsh. Further investigation is needed to ascertain if soil nutrient availability influences or is a result of the production and diversity differences that exist between vegetation zones of New England high salt marshes.
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  • 94
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    Investigational new drugs 17 (1999), S. 227-240 
    ISSN: 1573-0646
    Keywords: apoptosis ; protein kinase C ; sphingoid bases ; safingol ; diglyceride ; bryostatin 1 ; staurosporine ; 7-hydroxy staurosporine (UCN-01) ; 4′-N-benzoyl staurosporine (CGP-41251) ; calphostin C (UCN-1028c)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Neoplastic cell survival is governed by a balance between pro-apoptotic and anti-apoptotic signals. Noteworthy among several anti-apoptotic signaling elements is the protein kinase C (PKC) isoenzyme family, which mediates a central cytoprotective effect in the regulation of cell survival. Activation of PKC, and subsequent recruitment of numerous downstream elements such as the mitogen-activated protein kinase (MAPK) cascade, opposes initiation of the apoptotic cell death program by diverse cytotoxic stimuli. The understanding that the lethal actions of numerous antineoplastic agents are, in many instances, antagonized by cytoprotective signaling systems has been an important stimulus for the development of novel antineoplastic strategies. In this regard, inhibition of PKC, which has been shown to initiate apoptosis in a variety of malignant cell types, has recently been the focus of intense interest. Furthermore, there is accumulating evidence that selective targeting of PKC may prove useful in improving the therapeutic efficacy of established antineoplastic agents. Such chemosensitizing strategies can involve either (a) direct inhibition of PKC (e.g., following acute treatment with relatively specific inhibitors such as the synthetic sphingoid base analog safingol, or the novel staurosporine derivatives UCN-01 and CGP-41251) or (b) down-regulation (e.g., following chronic treatment with the non-tumor-promoting PKC activator bryostatin 1). In preclinical model systems, suppression of the cytoprotective function(s) of PKC potentiates the activity of cytotoxic agents (e.g., cytarabine) as well as ionizing radiation, and efforts to translate these findings into the clinical arena in humans are currently underway. Although the PKC-driven cytoprotective signaling systems affected by these treatments have not been definitively characterized, interference with PKC activity has been associated with loss of the mitogen-activated protein kinase (MAPK) response. Accordingly, recent pre-clinical studies have demonstrated that pharmacological disruption of the primary MEK-ERK module can mimic the chemopotentiating and radiopotentiating actions of PKC inhibition and/or down-regulation.
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  • 95
    ISSN: 1573-0646
    Keywords: UCN-01 ; IL-2 receptor ; Fas ; Fas-ligand ; apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract 7-hydroxystaurosporine (UCN-01) is a new anticancer agentwhich exerts an inhibitory effect on cell cycle check points andis currently under phase I clinical trials in US and Japan.Preliminary clinical data indicated that UCN-01 remained inplasma at high concentrations for long periods of time. Thisunavoidable high plasma drug exposure is likely to lead tohematological toxicities in patients. In the present study,cultured human peripheral blood lymphocytes (PBLs) were used toevaluate the possible hematological toxicities of UCN-01treatment. UCN-01 induces apoptosis, and the induction ofapoptosis-related surface markers were also examined toinvestigate the involvement of these molecules in UCN-01-inducedapoptosis in PBLs. in vitroviability of PBLs wasdecreased by high dose of UCN-01 (25 μM, 3-day exposure). Thiseffect of UCN-01 was significantly suppressed by the presence ofhuman serum, suggesting that some specific inhibitory factor(s)in human serum may antagonize the lympholytic effect of UCN-01.The percentage of annexin V-positive PI-negative cells increasedwith exposure to UCN-01 in a time- and dose-dependent manner; byup to 30.3% after exposure to 25 μM UCN-01 for 3 days.At the same time, the expression of both interleukin-2 receptor(IL-2R, CD25) and Fas (CD95), analyzed by flow cytometry, wasinduced. Con A-stimulated PBLs were more sensitive toUCN-01-induced apoptosis than non-stimulated lymphocytes andUCN-01 increased the sFas-L released into culture medium from conA-stimulated PBLs. Therefore, lymphocyte depletion mediated byactivation-induced apoptosis is likely to occur in patientstreated with UCN-01 at high doses.
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  • 96
    ISSN: 1573-0778
    Keywords: apoptosis ; Bcl-2 ; fixed-bed ; hollow fibre ; hybridoma ; perfusion ; protein-free medium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Apoptosis is an active, genetically determined death mechanism which can be induced by a wide range of physiological factors and by mild stress. It is the predominant form of cell death during the production of antibodies from murine hybridoma cell lines. A number of studies have now demonstrated that the suppression of this death pathway, by means of over-expression of survival genes such as bcl-2, results in improved cellular robustness and antibody productivity during batch culture. In the present study, the influence of bcl-2 expression on hybridoma productivity in two high density perfusion bioreactor systems was investigated. In the first system, a fixed-bed reactor, the DNA content in the spent medium was 25% higher in the control (TB/C3-pEF) culture than that found in the bcl-2 transfected (TB/C3-bcl2) cultures at all perfusion rates. This is indicative of a higher level of cell death in the control cell line. The average antibody concentration for the TB/C3-pEF cell line was 14.9 mg L-1 at perfusion rates of 2.6 and 5.2 d-1. However, for the TB/C3-bcl2 cell line it was 33 mg L-1 at dilution rates of 2 and 4 d-1. A substantial increase in antibody concentration was also found in the Integra Tecnomouse hollow fibre reactor. The antibody titre in the TB/C3-bcl2 cassette was nearly 100% higher than that in the TB/C3-pEF cassette during the cultivation period which lasted 6 weeks. Clearly, these results demonstrate the positive impact of bcl-2 over-expression on production of antibody in hybridoma perfusion cultures.
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  • 97
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    Aquatic ecology 33 (1999), S. 55-64 
    ISSN: 1573-5125
    Keywords: estuaries ; nitrogen ; oxygen depletion ; phosphorus ; regression model ; vertical mixing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a detailed analysis of oxygen saturation in a shallow Danish estuary it was possible to separate the effect of meteorological forcings (i.e. wind and solar radiation) and nutrient loads on oxygen depletion in bottom water. Regression analysis showed that oxygen saturation tied to nitrogen load rather than to phosphorus load. During summer periods of stratification the oxygen saturation could be attributed to the time elapsed after the onset of stratification and the accumulated nitrogen loading 10 month prior to measurement. Using a 10-year meteorological database and an empirical model it was calculated that a 25% reduction in nitrogen loading would reduce the number of days with severe oxygen depletion (i.e. 〈15% of saturation) by more than 50%.
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  • 98
    ISSN: 1573-0778
    Keywords: antibody productivity ; apoptosis ; BAG-1 ; Bcl-2 ; cell survival ; hybridoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Human bcl-2 and bag-1 DNA were introduced into mouse hybridoma 2E3- O cells and expressed. The expression of bcl-2 in BCMGneo-bcl2 transfectants was confirmed by ELISA and that of bag-1 in pZeo-bag1 was confirmed by western blotting. In batch cultures, the over-expression of bcl-2 prolonged the culture period by 2 days and co-expression of bcl-2 and bag-1 prolonged the culture period by 3 days. The delayed increase in the dead cell number in culture of the bcl-2 and bag-1 cotransfectant indicated the additional antiapoptosis effect of bcl-2 and bag-1 cotransfection in comparison with the bcl-2 only transfection. The bcl-2 transfectants (2E3O-Bcl2) produced antibody twofold per batch culture in comparison with 2E3-O cells transfected with BCMGSneo (2E3O-Mock). Enhancement of this MoAb production was due to the improved survival of the cells and was not due to stimulation of antibody production rate per cell by Bcl-2 expression. And the bcl-2 and bag-1 co-transfectant (2E3O-Bcl2-BAG1) produced antibody approximately fourfold of 2E3O-Mock per batch culture. Enhancement of this MoAb production was due to the improved survival of the cells and was partly due to stimulation of MoAb production rate per cell in the non-growing phase by the cotransfection. The method to engineer hybridoma cells genetically with bcl-2 and bag-1 for increasing viability and productivity would be widely applied for improving antibody productivity of hybridoma cultures.
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  • 99
    ISSN: 1573-0778
    Keywords: annexin V ; Apo-2 ligand ; apoptosis ; Cytostar-T® scintillating microplates ; flow cytometry ; lymphotoxin (LT)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The translocation of phospholipids across the plasma membrane has been widely documented as one of the earliest measurable biochemical events of apoptosis. Using fluorescently labelled annexin V, which preferentially binds phosphatidylserine (PS) in the presence of Ca2+, the externalization of PS can be measured and apoptosis quantified using flow cytometry. Conventional detection methods utilizing annexin V, while faster than in situ DNA end-labelling or DNA laddering, require extensive sample preparation which may compromise samples and makes rapid, high volume screening prohibitive. This paper describes a novel assay for the measurement of apoptosis based upon binding of radiolabelled annexin V to apoptotic cells attached to the growth surface of a 96-well scintillating microplate (Cytostar-T®). We compared measurements of apoptosis made by flow cytometry to those obtained with the scintillating microplate in three model systems, treatment of: mouse connective tissue (L-M) cells with lymphotoxin (LT), human lung carcinoma (H460) cells with Apo-2 ligand and human umbilical vein endothelial (HUVE) cells with staurosporine. In this assay, we compare both direct and indirect labelling methods by utilizing either iodinated annexin V or biotinylated annexin V/[35S] streptavidin to radiolabel apoptotic cells. The signal detected is a direct consequence of the binding of annexin V to externalized PS on apoptotic cells and the proximity of the label to the base of the plate. Using this method, separation of bound and unbound radiolabel signal occurs directly within the well resulting in a sensitive assay that requires minimal manipulation and can accomodate a large number of samples.
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  • 100
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    European journal of plant pathology 105 (1999), S. 61-76 
    ISSN: 1573-8469
    Keywords: core sampling ; foliar nutrient concentrations ; minirhizotrons ; nitrogen ; phosphorus ; potassium ; Rhizolab
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Potato-cyst nematodes (Globodera pallida) cause severe yield losses in potato. Plants infected with potato-cyst nematodes generally have reduced concentrations of nitrogen, phosphorus and potassium in the foliage. This study investigated whether reduced growth of nematode-infected potato is caused by nutrient limitation. Experiments in the field and in containers showed that phosphorus concentration correlated best with total crop biomass at early stages of growth. The role of phosphorus in nematode damage was further investigated in the field and in the Wageningen Rhizolab. The experimental field was infested with potato-cyst nematodes and two levels of nematode density were established by fumigation with a nematicide. Prior applications of calcium carbonate resulted in pHKCl levels of 4.8 and 6.1. Two levels of phosphorus fertiliser were applied: either 0 or 225 kg P ha−1. In the Wageningen Rhizolab, soil of both pH levels from the field was used after treatment with 1 MRad gamma irradiation to kill the nematodes. Subsequently, half of the soil was inoculated with cysts to give a nematode density of 30 viable juveniles per gram of soil. In the field, nine weeks after planting, the total crop biomass ranged from 107 g m−2 for the treatment with nematodes at pHKCl 6.1 without phosphorus fertiliser to 289 g m−2 for the fumigated treatment at pHKCl 4.8 with phosphorus fertiliser. The differences in total biomass for the various treatments were explained by differences in foliar phosphorus concentration. Nematodes induced or aggravated P deficiency and reduced total biomass. This was not the only damage mechanism as at high, non-limiting levels of foliar phosphorus concentration, nematodes still reduced total biomass. In the Wageningen Rhizolab, directly after planting, the number of roots visible against minirhizotrons was reduced by nematodes. However, the increase of root number in the nematode treatment continued longer than in the control, until root number was higher than that of the control. The compensary root growth of the nematode treatment was restricted to the top 30 cm and nematodes reduced rooting depth. High soil pH reduced growth, mainly by reducing the availability of phosphate. Both nematodes and high soil pH reduced nutrient uptake per unit root length. Our results lead us to suggest an interaction between nematodes and soil pH, with nematode damage being higher at pHKCl 6.1 than at pHKCl 4.8.
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