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  • 2000-2004  (9)
  • 1960-1964  (5)
  • 1920-1924
  • Phosphorus
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 32 (2000), S. 435-440 
    ISSN: 1432-0789
    Keywords: Keywords Fertilizer ; Long-term field experiment ; Manure ; Mycorrhiza ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  A pot experiment was conducted with soil from a long-term (74-year) fertilization field experiment to compare the effects of organic and mineral fertilizers on mycorrhiza formation in clover, and mycorrhiza-mediated plant P uptake. Five treatments were selected from the field experiment representing different forms and levels of P. Mycorrhizal effects on plant growth and P uptake were estimated by comparing plants grown in untreated soil containing indigenous arbuscular mycorrhizal (AM) fungi, with plants grown in pasteurized soil. Short-term versus residual effects of fertilizer/manure were also measured by comparing treatments with or without fertilizers added at the start of the pot experiment. Mycorrhiza formation was greatest in soil that had received no P for 74 years, followed by soil having received 30 or 60 Mg ha–1 farmyard manure (FYM), and soil having received 25 or 44 kg P ha–1 in NPK fertilizers. Plant growth and P uptake were severely reduced in the absence of AM fungi for all mineral fertilizer treatments. In contrast, plants growing in soil that had received FYM grew equally well or better when non-mycorrhizal. Recent additions of NK fertilizer and FYM had no effect on mycorrhiza formation, while additions of NPK led to reduced colonization. It thus seems that moderate quantities of FYM have less adverse effects on AM than equivalent amounts of nutrients in NPK fertilizers, a phenomenon that is most likely due to a temporal difference in P availability and its gradual release that balance plant demand.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 32 (2000), S. 328-339 
    ISSN: 1432-0789
    Keywords: Key words Biomass transfer ; Maize ; Phosphorus ; Resin extractable phosphorus ; Triple superphosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The effects of organic residues and inorganic fertilizers on P availability and maize yield were compared in a Nitisol of western Kenya. Leaf biomass of Calliandra calothyrsus, Senna spectabilis, Croton megalocarpus, Lantana camara, Sesbania sesban, and Tithonia diversifolia were incorporated into the soil at 5 Mg ha–1 for six consecutive seasons in 3 years and responses compared with those following the application of 120 kg N ha–1, 0 kg P ha–1 (0P); 120 kg N ha–1, 10 kg P ha–1; and 120 kg N ha–1 25 kg P ha–1 as urea and triple superphosphate (TSP); K was supplied in all treatments. Addition of Tithonia, Lantana and Croton increased soil resin-extractable P over that of fertilizer-amended soil throughout the first crop, but the amounts in the former treatments became similar to those for soils amended with inorganic fertilizers for subsequent crops. Addition of Sesbania, Calliandra and Senna had a similar effect on resin P as inorganic fertilizers. Total maize yields after six seasons were tripled by the application of Tithonia compared to 0P, and were higher than those of the Calliandra, Senna, Sesbania and Lantana treatments, and similar only to that of the Croton treatment. P recovered in the above-ground biomass and resin P, immediately after the implementation of the treatments, was higher in the Senna, Sesbania, Croton, Lantana and Tithonia (35–77%) treatments than in the inorganic fertilizer treatments (21–27%). The P content of organic residues, and the soluble C:total P ratio, were the main residue parameters predicting soil P availability and maize yield. All organic residues used in this study can replace inorganic fertilizers for the enhancement of P availability and maize production, while an additional benefit could be obtained from the use of Croton, Lantana and Tithonia.
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  • 3
    ISSN: 1432-0975
    Keywords: Keywords Coral ; Nitrogen ; Phosphorus ; Eutrophication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract  The effect of prolonged (9 week) nutrient enrichment on the growth and photosynthetic rates of the zooxanthellate coral Stylophora pistillata was investigated. The main questions were: (1) what is the exposure time needed to induce measurable change in growth rate? (2) which are the concentrations of nitrogen and phosphorus required to cause changes in these rates? (3) what is the recovery potential of the corals after the nutrient stress? For this purpose, three tanks (N, P, NP) were enriched with ammonium (N), phosphorus (P) or both nutrients (NP), respectively. A fourth tank (C) served as a control. The growth of 40 nubbins (10 in each tank) was monitored during four periods: period 1 (nutrient-poor conditions), period 2 (10 μm NH4 and/or 2 μm PO4 enrichment), period 3 (20 μm NH4 and/or 2 μm PO4) and period 4 (nutrient-poor conditions). Period 4 was performed to study the recovery potential of corals after a nutrient stress. During period 1, growth rates remained constant in all tanks. In the P tank, growth rates declined during the two enrichment periods, with a total decrease of 60% by the end of period 3. In the N tank, growth rates remained nearly constant during period 2 but decreased in period 3 (60% decrease). In the NP tank, 50% and 25% decreases were observed during periods 2 and 3. At the end of the recovery period, a regain in growth rate was observed in the N and NP tanks (35 and 30% increase, respectively, compared with the rates measured at the end of period 3) and growth rates returned to 60% of the initial rates. By contrast, in the P tank, there was no regain in growth and a further decrease of 5% was observed. Rates of photosynthesis were often higher during the enriched than the nutrient-poor period (up to 150% increase). Corals with the highest percent increases in maximal gross photosynthetic rate (P g max ) had the smallest decreases in growth rate due to nutrient enrichment. In conclusion, high ammonium (20 μm) and relatively low phosphorus concentrations (2 μm) are required to induce a significant decrease in coral growth rate. The largest reduction was observed with both ammonium and phosphorus enrichment. The decrease in growth rate was rapid following nutrient enrichment, since a 10% decrease or more could be observed after the first week of treatment.
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  • 4
    ISSN: 1435-5604
    Keywords: Key words Calcium ; Phosphorus ; PTH ; Bone meal powder
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To evaluate the effects of bone meal powder (BEC) on calcium and phosphorus metabolism, a calcium absorption test was conducted using a preparation of calcium carbonate (CAC) as the control drug. A total of 12 healthy volunteers, consisting of 6 younger (aged 20–29 years, 3 men and 3 women) and 6 older (aged 60–69 years, 3 men and 3 women) persons, were subjected to a double-blinded crossover study. Serum calcium (s-Ca) level significantly increased to 105.3% ± 1.9% (P 〈 0.01 vs the basal value; mean ± SD) from the basal value in the BEC group and to 104.4% ± 2.7% (P 〈 0.01) in the CAC group at 3 h post load. Urinary excretions of calcium (u-Ca/glomerular filtration rate, u-Ca/GF) after BEC and CAC load rose to 226.6% ± 154.5% (P 〈 0.05) and 211.1% ± 148.0% (P 〈 0.05), respectively. Serum phosphorus (s-P) levels after BEC load increased to 110.0% ± 15.1% (P 〈 0.05), whereas that after CAC load showed no significant change (99.3% ± 7.9%). On the other hand, urinary excretion of phosphorus (u-P/GF) after CAC load decreased to 60.0% ± 32.4% (P 〈 0.01) and that in the BEC group showed no significant change (92.5% ± 49.5%). The increase in s-Ca led to decrease in serum intact parathyroid hormone (i-PTH) level [77.3% ± 33.4% (P 〈 0.05) for BEC and 69.5% ± 20.3% (P 〈 0.01) for CAC] although s-P was increased by the BEC load. The responses to BEC and CAC administration were compared in the younger and the older groups. The responses in the younger and the older group showed fundamentally the same trends and to the same extent. However, the changes in serum ionized calcium (i-Ca) and i-PTH levels at 1.5 h post load were significantly smaller in the older group than in the younger group (P 〈 0.01; P 〈 0.05). The increment in s-P level after BEC load in the older group was larger than that in the younger group. In conclusion, BEC can modulate not only calcium but also phosphorus metabolism in both younger and older subjects. Further investigations are required to evaluate the effects of BEC on bone density and safety for renal function in long-term observations.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 2000 (2000), S. 103-112 
    ISSN: 1434-1948
    Keywords: Ab initio calculations ; Ionization potentials ; Phosphorus ; Heterocycles ; Small ring systems ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio quantum chemical calculations have been used to explore the P3H3 potential energy surface focussing on the ring-chain rearrangements of the three-membered ring in (PH)3 (1), the parent triphosphirane. Relative energies between stationary points were estimated using the QCISD(T)/6-311G(d,p) method based on MP2/6-31G(d,p) geometries and corrected for zero-point contributions. Ring strain, proton affinities, ionization and excitation energies and heats of formation have been evaluated using larger basis sets, e.g. 6-311++G(3df,2p). The cyclic trans-triphosphirane (1a) is the most stable P3H3 isomer and lies about 40 kJ/mol below the open-chain phosphanyldi-phosphene (H2P-P=PH). The decrease of ring strain in three-membered rings when CH2 is replaced by PH is confirmed. Triphosphirane 1a is a virtually strain-free ring and even gains some stabilization relative to three separate P-P single bonds. The reduced ring strain also helps diminish the phosphorus inversion barrier to 224 kJ/mol compared to the monocyclic isomers of (CH2)(PH)2 and (CH2)2(PH). Compound 1a follows a pure ring-opening or a 1,2-hydrogen shift rather than a combined motion pathway, in fundamental contrast with corresponding processes of diphosphirane and phosphirane. This is due to the existence of an open-chain P3H3 phosphorane intermediate stabilized by allylic conjugation. The pericyclic ring-opening of 1a is the most favored process but the energy barrier in the gas phase is about 180 kJ/mol high. Electron density is largely delocalized within the three-membered P3 ring not only in the C3v-symmetric 1b (all-cis) but also in 1a (Cs). The proton affinity of 1a is similar to that of PH3. The proton affinities decrease with n in cyclo-(CH3)3 -n(PH)n and their values were obtained: PA(1a) = 777 ±10, PA(diphosphirane) = 799 ±10 and PA(phosphirane) = 802 ±10 kJ/mol. Heats of formation are evaluated as follows (ΔH°f0 at 0 K in kJ/mol): 1a, 70 ±10; cyclo-(PH)2(PH2)+ (protonated 1a), 821 ±10; diphosphirane, 85 ±10; cyclo-(CH2)(PH)(PH2)+ (protonated diphosphirane), 814 ±10; phosphirane, 86 ±10; and protonated phosphirane, 812 ±10 kJ/mol. All P rings remain cyclic following ionization to the radical cations. Adiabatic ionization energies (IEa) are estimated as: 1a and diphosphirane, 9.3 ±0.3 eV and phosphirane 9.5 ±0.3 eV. The first UV absorption band shifts toward the longer wavelength region on going from phosphirane to 1a. The GIAO/B3LYP computed magnetic shieldings for 1a and related molecules reveal a clear relationship between the narrow bond angles in the rings and their unusually strong magnetic shielding. The similarity of the predicted 31P-NMR signals in 1a and its heteroanalog diphosphirane, (CH2)(PH)2, can be rationalized in terms of a compensation of the carbon-substituent effect (downfield shift) and the bond-bending effect imposed by the ring (upfield shift).
    Additional Material: 5 Ill.
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  • 6
    ISSN: 1434-1948
    Keywords: Thiophosphites ; X-ray diffraction ; Manganese ; Iron ; Phosphorus ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thioesters of the phosphorous acid containing cymantrenyl and ferrocenyl substituents at sulfur were obtained for the first time from the reaction of organometallic disulfides with white phosphorus. According to an X-ray diffraction study tricymantrenyl trithiophosphite adopts an unusual asymmetric cis, gauche, trans conformation along the P-S bonds with respect to the phosphorus lone electron pair. Triferrocenyl trithiophosphate possesses a classical propeller-like structure in the solid state which is different from its oxygen analogue.
    Additional Material: 3 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 2000 (2000), S. 417-421 
    ISSN: 1434-1948
    Keywords: Phosphorus ; Benzynezirconocenes ; Azazirconacyclopentenes ; Exchange reactions ; 1,2-Azaphosphindole ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The first 1,2-azaphosphindoles 14a,b, 15a,b were obtained in a straightforward manner upon heating diphenylzirconocene in the presence of a cyanophosphane, which afforded azazirconacyclopentenes 11a,b which can be reacted with various dichlorophosphanes. The use of the tetrachlorodiphosphane Cl2P(CH2)2PCl2 instead of a dichlorophosphane allowed the preparation of the bis(1,2-azaphosphindoles) 19, 19′. The monosulfur adduct of the azaphosphindole 14a, i.e. 16a, was characterized by X-ray structure analysis. Alkylation of 14a or 16a with methyltrifluoromethane sulfonate occurred selectively on the intracyclic phosphorus atom or on the sulfur atom, giving the salts 20 or 21, respectively.
    Additional Material: 1 Ill.
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  • 8
    ISSN: 1615-6102
    Keywords: Allium porrum ; Arbuscular mycorrhiza ; Mitotic cycle ; Phosphorus ; Root apex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Arbuscular mycorrhizal (AM) fungi significantly improve plant growth in soils with low phosphorus availability and cause many changes in root morphology, similar to those produced by increased P nutrition, mainly depending on root apex size and activity. The aim of this work was to discriminate between the morphogenetic role of AM fungi and P in leek (Allium porrum L.) by feeding mycorrhizal and nonmycorrhizal plants with two nutrient solutions containing 3.2 or 96 μM P and examining specific parameters related to adventitious root apices (apex size, mitotic cycle, and RNA synthesis). The results showed that AM fungi blocked meristem activity as indicated by the higher percentages of inactive apices and metaphases in the apical meristem of mycorrhizal plants, whereas the high P supply lengthened the mitotic cycle without blocking the apices, resulting in steady, slow root growth. The possible involvement of abscisic acid in the regulation of root apex activity is discussed.
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  • 9
    ISSN: 1434-1948
    Keywords: Hypercoordinated phosphorus ; Hypervalent phosphorus ; Phosphorus ; Diphosphonium compounds ; Ionomers ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Starting from R′R2P (R′ = 8-dimethylamino-1-naphthyl) containing a donor dimethylamino group, the new phosphonium salts [R′R2P(CH2Ph)]+Br- [R = Me (9) or Ph (10)] and [R′R2P(p-CH2C6H4CH2)PR2R′]2+[2Br]2- [R = Ph (12)] have been prepared. An interaction between the N and P atoms is evident from the X-ray crystal structure of 10 the N-P distance being less than the sum of the van der Waals radii of the 2 atoms. The geometry of 10 is that of a monocapped tetrahedron whereas the X-ray crystal structure determination shows essentially regular tetrahedral geometry for the analogous compound without the donor amino group, [(1-Np)Ph2P(CH2Ph)]+Br- (11). Treatment of 1,5-bis(dimethylamino)-2,6-dilithionaphthalene with chlorodiphenylphosphane gave 1,5-bis(dimethylamino)-2,6-bis(diphenylphosphanyl)naphthalene (8) which in the presence of methyl iodide afforded the diphosphonium salt [1,5-bis(dimethylamino)-2,6-bis(diphenylmethylphosphonium)naphthalene]2+[2I]2- (13). Similarly, treatment of 8 with 1 equivalent of benzyl bromide gave the monophosphonium salt [1,5-bis(dimethylamino)-2diphenylbenzylphosphonium-6-diphenylphosphanyl-naphthalene]+[Br]- (14) whereas in the presence of 2 equivalents of the same reagent [1,5-bis(dimethylamino)-2,6-bis(diphenylbenzylphosphonium)naphthalene]2+[2 Br]2- (15) was obtained. The ionomer poly([(1,5-bis{dimethylamino}2,6-bis{diphenylphosphonium}naphthalene)-(P,P-p-xylylene)]2+[2 Br]2-) (16), soluble in liquid SO2, was prepared by treatment of 8 with α,α′-dibromo-p-xylene.
    Additional Material: 2 Ill.
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  • 10
    ISSN: 0570-0833
    Keywords: Tetradentate ligands ; P ligands ; Arsenic ligands ; Phosphorus ; Arsenic ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of ligand shape on coordination numbers and geometry of coordination compounds has been studied using two tetradentate ligands containing phosphorus and arsenic. These tend to form five-coordinate complexes with trigonal bipyramidal structure [Fe(II), Co(I), Co(II), Rh(I), Ni(II), Pd(II), Pt(II)], but can also form six-coordinate complexes with octahedral structure [Fe(II), Ru(II), Os(II), Co(III), Rh(III), Pd(IV), Pt(IV)]. The magnetic properties and the stereochemistry of the complexes are explained by ligand field theory which predicts that, for metal ions with d6-electronic configuration, a low overall field strength should favor the formation of five-coordinate paramagnetic complexes while a high overall field strength should favor the formation of six-coordinate diamagnetic complexes. - This work provides further indication that the tendency of polydentate ligands to use all the potential donor atoms is not as pronounced as is generally believed. This is shown by the isolation of chromium(III) complexes in which the tetradentate ligands are, in fact, acting as tridentate, and by the isolation of mercury(II) complexes where only two of the four donor atoms of the polydentate ligand are actually bonded to the central metal atom.
    Additional Material: 9 Ill.
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  • 11
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 523-530 
    ISSN: 0570-0833
    Keywords: Semimetals ; Metallic structure ; Nonmetallic structure ; Antimony ; Arsenic ; Bismuth ; Phosphorus ; Tellurium ; Tin ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Measurements on semimetals have been continued. Studies of the dependence on temperature of various properties have provided details regarding the transition from the nonmetallic to the more metallic structure. A second-order transition has been found for tin at 170 °C, in which the c-axis remains unchanged, while the a-axis undergoes a small, discontinuous elongation.
    Additional Material: 13 Ill.
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  • 12
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 646-654 
    ISSN: 0570-0833
    Keywords: Polyphosphanes ; Phosphanes ; Phosphorus ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: While silicon and sulfur, which are situated to the left and to the right of phosphorus in the periodic table, from numerous chain and cyclic Si-Si and S-S-compounds with varying numbers of members, until recently the polyphosphance chemistry has been limited to the two-membered compounds diphosphane P2H4 and its derivatives. A number of results obtained in studies on polyphosphanes carried out in recent years will therefore be discussed, which, together with some more recent work by other authors, have led to an expansion of our knowledge of the prepration and properties of straight and branched-chain as well as of cyclic and polycylic -P-P-systems.
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  • 13
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 617-621 
    ISSN: 0570-0833
    Keywords: Isocyanates ; Phosphorus ; Silicon ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several aminoaryl esters of phosphoric and thiophosphoric acids were prepared by the reaction of phosphorus pentahalides with nitrophenols, followed by catalytic hydrogenation, or by treating aminophenols with phosphorus trihalides and oxidation to pentavalent phosphorus. These amino esters were then converted into isocyanato esters by the action of phosgene. Isocyanates of phosphonates have been synthetized on the same principle, as well as via the Arbusov reaction of halogen-substituted isocyanates with trialkyl phosphites. The reaction of silicon halides or alkylhalogenosilanes with aminophenols yielded aminoaryl esters of silicic acid or its derivatives, which could also be treated with phosgene to convert them into isocyanato esters.
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  • 14
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 652-656 
    ISSN: 0570-0833
    Keywords: β-Chloroethanephosphonic dichloride ; Phosphorus ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ethylene, phosphorus trichloride, and oxygen react together to give β-chloroethylphosphonic dichloride in good yields. Being a bifunctional acid chloride, this compound undergoes polycondensation reactions with other, at least bifunctional, compounds affording polyesters, polyamides, epoxy resins, etc. β-Chloroethylphosphonic dichloride also may be converted into vinylphosphonic dichloride, thus serving as a starting material for the preparation of vinylphosphonic acid and its derivatives. These undergo both homopolymerization and copolymerization with compounds containing olefinic double bonds. The products are used in the field of synthetic resins, for dressing textiles, and as protective surface coatings.
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