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  • 1990-1994  (57)
  • 1960-1964  (19)
  • 1925-1929
  • 1920-1924
  • 1905-1909
  • Fibers
  • Phosphorus
  • Reaction mechanisms
  • 1
    Electronic Resource
    Electronic Resource
    Molecular size distribution and enzymatic degradation of organic phosphorus in root exudates of spring barley (1994)
    Springer
    Biology and fertility of soils 18 (1994), S. 285-290 
    Details
    ISSN: 1432-0789
    Keywords: Exudates ; Hordeum vulgare ; Gel filtration ; Phosphatases ; Phytase ; Phosphorus ; Roots
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Seeds from two varieties of spring barley (Prisma and Camorgue) were grown axenically in water. After 14 days, the culture solutions contained organic P substances (about 4 μg P per plant) derived from root exudation, representing about 3% of the total P found in the seed. Gel filtration, separated the organic P into two well defined peaks, one with a high molecular weight (〉45000 daltons) and the other with a low molecular weight (〈500 daltons). The bioavailability of the soluble organic P released was assessed enzymatically and chemically. At the optimum pH of 5.0, phytase and acid phosphatase hydrolysed about 80% and 65%, respectively of the organic P in the exudate after 24 h whereas at the optimum pH of 9.8, alkaline phosphatase hydrolysed up to 40% P after the same length of time. In a pH 5.0 buffer, up to 10% of the organic P was hydrolysed compared with up to 45% in a pH 9.8 buffer. The high molecular weight organic P fraction recovered from the G-75 Sephadex behaved similarly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00570630
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  • 2
    Electronic Resource
    Electronic Resource
    Fractionation of phosphorus in the sediments of a tropical estuary (1994)
    Springer
    Environmental geology 23 (1994), S. 284-294 
    Details
    ISSN: 1432-0495
    Keywords: Phosphorus ; Fractionation ; Sediments ; Tropical estuary ; India
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Fractionation of phosphorus in the sediments of the Cochin estuary situated along the southwest coast of India was studied by applying sequential chemical extraction. The different forms of phosphorus were estimated seasonally (premonsoon, monsoon, and postmonsoon) under eight different schemes. The major forms of phosphorus analyzed were exchangeable P, anion exchangeable P, carbonate-bound P, labile and resistant organic P, Fe and Al P, calcium-bound P, and hydrolyzable surplus P. Quantitatively, the above fractions in isolation or in combination vary in content due to chemoestuarine variability and seasonal fluctuations. Changes in speciation have been noted in association with salinity variations in the waterway, especially following enhanced river runoff during the monsoon. The chemical forms of the sediment-bound phosphorus in the northern parts of this estuary have been shown to be modified by nonpoint sources. Sediment P fractionation defines the role of chemical speciation of phosphates (as nutrients) and is indicative of the processes controlling the pathways of P into the coastal waters. The changes in the exchangeable P, together with marked regional variations in calcium-bound P, exemplify the complex estuarine variability of phosphorus. Enhanced amounts of exchangeable P mark its appearence in high saline waters, signifying the presence of biologically available nutrient phosphorus. The calcium-bound P and hydrolyzable surplus P show significant relation with sediment organic carbon and Fe whereas other forms do not exhibit any marked covariation. The Ca and Na NTA extraction scheme is very specific in its selectivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00766744
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  • 3
    Electronic Resource
    Electronic Resource
    Decomposition and nutrient content of litter in a fertilized eucalypt forest (1994)
    Springer
    Biology and fertility of soils 17 (1994), S. 159-166 
    Details
    ISSN: 1432-0789
    Keywords: Eucalypt forest ; Litter decomposition ; Fertilizer ; Nitrogen ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The decomposition and nutrient content of litter was studied for 2 years in regrowth Eucalyptus diversicolor forest to which N (0, 200 kg ha-1 year-1) and P (0, 30, 200 kg ha-1) had been applied. The P addition increased, and the N addition decreased, the rate of dry weight loss of decomposing litter. Analysis of the coefficients of a double exponential decay model with components describing the release of labile and resistant fractions indicated that decomposition of the resistant component of litter was most affected by the fertilizer additions. Treatment with N reduced the rate of loss of this component and increased its half-life by approximately 30%, whereas P treatment increased its rate of decay and decreased its half-life by approximately 30%. P accumulated in litter during decomposition. P uptake and retention was greater in P-treated than untreated plots. The application of N reduced P accumulation in litter. An accumulation of N also occurred during decomposition, the amount of N imported into litter being greater on plots treated with N fertilizer. Treatment with N affected the amount of S in decomposing litter. Litter on N-treated plots either accumulated more S or released it more slowly than litter on plots not treated with N. The application of N as NH4NO3 decreased forest-floor litter pH, increased litter layer mass (by 15%), and increased the amount of N (by 34%) and S (by 32%) stored in the forest floor. Treatment with P reduced the amount of N (by 22%) stored in the litter layer. The application of 200 kg P ha-1 in the absence of N increased the store of P in the litter layer by 80%, but when N and P were applied together the amount of P in the litter was not significantly different between P treatments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00337749
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  • 4
    Electronic Resource
    Electronic Resource
    Extraction, molecular fractionation and enzyme degradation of organically associated phosphorus in soil solutions (1994)
    Springer
    Biology and fertility of soils 17 (1994), S. 196-200 
    Details
    ISSN: 1432-0789
    Keywords: Phosphorus ; Fractionation ; Phosphatase ; Hydrolysis ; Organic phosphorus ; Hordeum vulgare
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The concentrations and chemical composition of water-extractable P were compared in four soil types from NE Scotland. All sites were sampled during the early establishment phase of a spring barley (Hordeum vulgare) crop. The quantity of total soluble P extracted ranged from 〈2.0 to 10 mg P kg soil-1, of which up to 50% was classified as being organically associated. Sample fractionation showed that both orthophosphate inorganic P and organic P were associated with a wide molecular-size range of organic material. A strong positive correlation was readily apparent between P and the sum of Fe + Al in the fractionated samples. The extent of enzymatic hydrolysis of organic P varied between soil samples and the type of enzyme. Phytase consistently produced the greatest degree of hydrolysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336322
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  • 5
    Electronic Resource
    Electronic Resource
    Water quality management in the River Gudenaa, a Danish lake-stream-estuary system (1994)
    Springer
    Hydrobiologia 275-276 (1994), S. 499-507 
    Details
    ISSN: 1573-5117
    Keywords: Eutrophication ; Management ; Lake ; Stream ; Estuary ; Phosphorus ; Nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Waste water purification has been established to some extent throughout the 3,260 km2 catchment area of the River Gudenaa water system during the last 20 years. Biological treatment and phosphorus removal are now undertaken in almost all towns, and organic matter and phosphorus loading from fishponds and farms has been reduced. The pollution abatement strategy employed has been to coordinate and differentiate waste water treatment so as to maximise the environmental benefit/cost ratio. The time lag between implementing an abatement measure and observing an improvement in water quality varies considerably depending on the nature and cultural history of the water bodies involved and the processes occurring during the passage of water between them. Nutrient transformation and retention within water bodies of the Gudenaa system is of great importance for nutrient loading of the downstream lakes and of the estuary (Randers Fjord), and even for the Danish Belt sea. When loading is reduced retention changes, but to a different extent in different water bodies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00026738
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  • 6
    Electronic Resource
    Electronic Resource
    Fe(I)-Mediated Regio- and Stereoselective C—C/C—H Bond Activation of Internal Methylene Groups of α,ω-Diphenylalkanes (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 261-265 
    Details
    ISSN: 0009-2940
    Keywords: Bond activation ; C—H ; C—C ; Iron chemistry ; Reaction mechanisms ; Chelate effects ; Tandem mass spectrometry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: For three α,ω-diphenylalkanes the mechanistic details of the Fe+-mediated activation of C—H and C—C bonds in the gas phase have been elucidated by isotopic labelling experiments. The unimolecular reactions, i.e. dehydrogenation of the alkane chain, formation of ethylene from internal methylene groups, and generation of toluene, proceed largely with high selectivity. Particularly interesting are the results for the dehydrogenation of the Fe+ complex 3-Fe+ of 1,8-diphenyloctane which involves to 93% the internal methylene groups C-4/C-5. In addition, the study of the stereoisotopomers 3c-d provides evidence for the operation of isotopically sensitive branching (“metabolic switching”) in the reaction, and the analysis of the data suggests that the selectivity of the reaction is, most likely, due to a sandwich-type structure.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270136
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  • 7
    Electronic Resource
    Electronic Resource
    Ein einfacher Weg zu Silicium in oktaedrischer Sauerstoffkoordination (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1213-1218 
    Details
    ISSN: 0009-2940
    Keywords: Silicon ; Octahedral oxygen coordination ; Phosphorus ; NMR, 1H MAS ; NMR, 29Si MAS ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Simple Route to Silicon in Octahedral Oxygen CoordinationSyntheses and crystal structures of three new compounds Rb2SiP4O13 (1), Cs2H2Si(P2O7)2 (2), and BaH2Si(P2O7)2 (3) containing silicon in an octahedral oxygen coordination are reported. The structures have been determined by X-ray structure analyses. All three compounds are constituted of silicophosphate polyanions. The NMR chemical shifts of silicon and hydrogen are measured.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270706
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  • 8
    Electronic Resource
    Electronic Resource
    Scales of Nucleophilicity and Electrophilicity: A System for Ordering Polar Organic and Organometallic Reactions (1994)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 33 (1994), S. 938-957 
    Details
    ISSN: 0570-0833
    Keywords: Reaction mechanisms ; Nucleophilicity ; Electrophilicity ; Carbocations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Contrary to widely held opinion, for many reactions in organic and organometallic chemistry it is possible to define nucleophilicity and electrophilicity parameters that are independent of the reaction partners. This phenomenon, discovered by Ritchie during the early 1970s for reactions of highly stabilized carbenium and diazonium ions with n-nucleophiles, also occurs with reactions of carbenium ions with aliphatic and aromatic π-electron systems and in hydride transfer reactions. With the aid of the scales of nucleophilicity and electrophilicity set out here, which extend over eighteen orders of magnitude, forecasts can be made about the feasibility and rate of a given CC bond formation, ionic reduction, or diazo coupling. Linkage with the reactivity scales of Ritchie and Sweigart/Kane-Maguire enables a unified treatment of a large number of polar reactions.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.199409381
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  • 9
    Electronic Resource
    Electronic Resource
    Organizing Principle of Complex Reactions and Theory of Coarctate Transition States (1994)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 33 (1994), S. 255-276 
    Details
    ISSN: 0570-0833
    Keywords: Rearrangement ; Coarctate transition states ; Reaction mechanisms ; Concerted reactions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The majority of concerted reactions proceeds by a simultaneous breaking and making of only one bond at each atom involved in the reaction. If this process follows an alternating cyclic sequence, the reactions are called pericyclic. However, there is a hitherto never consistently characterized class of reactions that proceeds by breaking and making two bonds at one or more atoms at a time. The striking relationships that are purely descriptive and formal in the first instance are explained by a common physical principle. Theoretical insight not only permits predictions of mechanisms and stereochemistry; the qualitative theory is also used as an organizing principle for the known reactions and as a tool for predicting unprecedented reactions of this type.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.199402551
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  • 10
    Electronic Resource
    Electronic Resource
    Time-Resolved Photoacoustic Calorimetry: From Carbenes to Proteins (1994)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 33 (1994), S. 294-302 
    Details
    ISSN: 0570-0833
    Keywords: Calorimetry ; Photoacoustic calorimetry ; Reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Why have molecules only been seen but not heard? For over a century chemists have probed reactions with various spectroscopic methods to learn about structures, dynamics, and reactivities of their molecules. What they have not done is to listen to their molecules react. Although the photoacoustic phenomenon has been known since 1880, it is only in the last twenty years that technology has developed to the point where sound waves produced by reacting molecules can be time resolved and the information contained within the waves deciphered. The information content within the photoacoustic wave is indeed rich, for one can learn about the dynamics and the magnitude of enthalpy changes associated with the reaction as well as the changes in molecular volume. This review article chronicles the development of time-resolved photoacoustic calorimetry and its application to a variety of reactions encountered in organic and organometallic chemistry and biochemistry.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.199402941
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  • 11
    Electronic Resource
    Electronic Resource
    Impact of some commonly used Egyptian diets on plasma lipids profils of rats (1993)
    Springer
    European journal of nutrition 32 (1993), S. 229-236 
    Details
    ISSN: 1436-6215
    Keywords: Fibers ; rats ; Plasma lipids ; Ratten ; Plasmalipide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung An hyperlipämischen Ratten wurde der Einfluß von 7 üblichen ägyptischen Kostformen geprüft. Die Ernährung bestand aus weißen Bohnen und Weizenvollkornbrot (Diät 1), Kohl und Erbsen (2), Spinat und Karotten (3), Weizenvollkornbrot und Bohnensprossen (4), Weizenvollkornbrot, weißen Bohnen und Erbsen (5), weißen Bohnen und Karotten (6) und schließlich Erbsen und Karotten (7). Die Versuche dauerten 5 Wochen, danach wurden verschiedene Plasmalipide und biologische Parameter mit hyperlipämischen Kontrolltieren verglichen. Das Gesamtplasmacholesterol war in allen Versuchsgruppen erniedrigt; eine Ausnahme machte Diät 6, hier gab es keine Senkung. Erniedrigt waren die Gesamtplasmalipide in Gruppe 5. Plasmaphospholipide stiegen an in den Gruppen 3 und 7. In Gruppe 3 war das HDL-Cholesterol erniedrigt. Die Gewichtszunahmen in den Gruppen 1, 2 und 3 waren reduziert. Ein verminderter Futterverzehr wurde in den Gruppen 1 und 6 beobachtet. Die Futterverwertung sank in den Gruppen 1, 5 und 6. In allen 7 Gruppen war das Gewicht der Faeces erhöht.
    Notes: Summary Seven types of diets commonly consumed in Egypt were studied in hyperlipemic rats. Each of the seven diets were fed to a group of hyperlipemic rats. The diets contain white beans and whole wheat bread (Diet 1); cabbage and peas (2); spinach and carrots (3); whole wheat bread and bean sprouts (4); whole wheat bread, white beans and peas (5); white beans and carrots (6) and the last diet contains peas and carrots (7). The experiment continued for 5 weeks, at the the of which different plasma lipids and biological parameters were compared to hyperlipemic rats fed the control diet for 5 weeks. Results showed that plasma total cholesterol of rats of all groups showed significant decrease, except in rats fed diet 6 in which no significant change was noticed. Plasma total lipids of rats fed diet 5 decreased significantly. Plasma phospholipids of rats fed diets 3 and 7 increased significantly. Rats fed diet 3 showed decreased levels of plasma high density lipoprotein-cholesterol. Body weight gain of rats fed diets 1, 2 and 3 decreased significantly. Total food intake was noticed to decrease on feeding diets 1 and 6. Significant decrease was produced in food efficiency ratio of rats fed diets 1, 5 and 6. Feeding any type of the previous seven diets produced significant increase of feces weight.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01610733
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  • 12
    Electronic Resource
    Electronic Resource
    Use of soil transfer for reforestation on abandoned mined lands in Alaska (1993)
    Springer
    Mycorrhiza 3 (1993), S. 97-106 
    Details
    ISSN: 1432-1890
    Keywords: Soil transfer ; Reforestation ; Populus ; Phosphorus ; Boreal forest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Soil transfers, presumed to contain mycorrhizal fungal inoculum from a native plant community, were applied to rooted cuttings and volunteer plants of Populus balsamifera L. to improve their growth on an abandoned mined site in south central Alaska. The objectives of the study were to determine (1) if these soil transfers could be substituted for additional P fertilizer when applied with a base level of NP fertilizer to improve growth, and (2) if P added to treatments receiving a base level of NP fertilizer and soil transfer would suppress mycorrhizal formation. Physical dimensions of plants were measured near the beginning and end of each of two growing seasons. Several plants per plot were harvested at the end of year 2 to determine mycorrhizal formation, current growth, and leaf nutrient concentrations. Plant height was significantly increased only when soil transfer and additional P treatments were combined. Response to additions of P fertilization alone or soil transfer alone were not significantly different from each other. Current twig growth increased with either treatment alone or both combined. Soil transfer on cuttings resulted in more ectomycorrhizal formation than either the control or additional P. Leaf N concentrations on cuttings and volunteers increased when plants were treated with soil transfer. Similar growth responses were achieved by soil transfers or additional P, but mycorrhizal formation was improved with the soil transfer treatments. P added to the base level plus soil transfer did not suppress or improve mycorrhizal formation compared to that with soil transfer alone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00208917
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  • 13
    Electronic Resource
    Electronic Resource
    Inefficient nitrogen resorption in genets of the actinorhizal nitrogen fixing shrubComptonia peregrina: physiological ineptitude or evolutionary tradeoff? (1993)
    Springer
    Oecologia 94 (1993), S. 542-549 
    Details
    ISSN: 1432-1939
    Keywords: Actinorhizal plants ; Evolutionary tradeoffs ; Nitrogen fixation ; Nutrient resorption ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nutrient resorption was measured in an actinorhizal nitrogen-fixing shrub,Comptonia peregrina, for five years in the understory of a deciduous oak forest in Rhode Island, USA. Mean resorption of nitrogen was extremely inefficient (11%) compared to most deciduous species (50%+), yet resorption of phosphorus was efficient (53%) and comparable to other species. Of the seven additional nutrients studied, only copper (6%) and zinc (10%) were resorbed from senescing leaves. Resorption of nitrogen (5%–20%) and phosphorus (40%–71%) varied significantly among years. Copper was resorbed from leaves in three years and accreted into leaves in two years. Five-year resorption means differed among individual genets by as much as a factor of 2.5 for nitrogen, and 1.3 for phosphorus. Resorption of nitrogen, copper, and zinc were highly correlated, yet resorption of phosphorus remained autonomous from other nutrients. The ecophysiological tradeoffs inComptonia which have resulted in the cooccurence of actinorhizal nitrogen fixation, inefficient nitrogen resorption, and efficient phosphorus resorption suggest that plant nutrient status does have an impact on resorption efficiency and that the evolution of nutrient conservation strategies is nutrient-specific.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566970
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  • 14
    Electronic Resource
    Electronic Resource
    Effects of the mineral composition and water content of intact plants on the fitness of the African armyworm (1993)
    Springer
    Oecologia 95 (1993), S. 401-409 
    Details
    ISSN: 1432-1939
    Keywords: Spodoptera exempta ; Gravel culture system ; Nutritional ecology ; Nitrogen ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of organic nitrogen, nitrate, phosphorus, potassium and water content of leaves of intact maize plants, grown in a gravel culture system, on the fitness of the African armyworm, Spodoptera exempta (Walker)(Lepidoptera: Noctuidae) were studied. Organic nitrogen concentrations ranged from 1.3% to 3.7% over four treatments differing only in nitrate supply to the plants. Water content and other mineral levels were all positively correlated with the organic nitrogen level. Feeding damage by the caterpillars was most severe on the lowest nitrate treatments, where it could be least well compensated for by new leaf growth. Larval and pupal fitness variables were not affected by treatment, except for larval development on the lowest nitrate treatment which was delayed by just 1 day. The large compensatory capacity of the larvae was underlined by a similar mineral composition of the pupae in all treatments. Adult fitness variables hardly differed between the upper three nitrate treatments, but revealed a trend over all treatments: the higher the organic nitrogen content of the leaves, the shorter the pre-oviposition period and the higher the fecundity. This trend, however, might have been due to differences in available food quantity rather than in food quality. It is concluded that fitness of the African armyworm is only slightly affected over a wide range of nitrogen concentrations in its food. Though effects might be larger under field conditions, the large differences in outbreak development between years seem not to be attributable to observed differences in nitrogen levels in host plants between years in primary outbreak areas. Other environmental factors appear to be of greater importance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00320995
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  • 15
    Electronic Resource
    Electronic Resource
    Responses of mycorrhizae and shoot phosphorus of maize to the frequency and timing of soil disturbance (1993)
    Springer
    Mycorrhiza 4 (1993), S. 63-68 
    Details
    ISSN: 1432-1890
    Keywords: Arbuscular mycorrhizae ; Vesicular-arbuscular mycorrhizae (VAM) ; Maize ; Phosphorus ; Soil disturbance ; Hyphal length
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In several growth chamber studies, both P absorption and mycorrhizal colonization of plants grown in soil left undisturbed after removal of the shoots of the previous crop were higher relative to plants in disturbed soil. However, in one of these studies the soil was disturbed only once instead of after each of three growth cycles, and this resulted in identical colonization in the undisturbed and disturbed treatments. The present study was conducted to systematically investigate the effect of varying the frequency and timing of soil disturbance on mycorrhizal colonization. Maize (Zea mays L.) was grown for four 3-week cycles in pots which initially contained disturbed soil. Five soil disturbance treatments were used to assess the impact of the frequency with which soil is disturbed and the impact of the timing of the disturbance. The frequency of soil disturbance had major effects on mycorrhizal colonization, while the timing of soil disturbance was more related to the reduction in shoot P absorption resulting from disturbance. These results suggest that the extraradical mycelium plays a key role in the mechanism by which soil disturbance reduces shoot P absorption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00204060
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  • 16
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of the degradation of la-acetylmitomycin C in aqueous solution (1993)
    Springer
    Pharmacy world & science 15 (1993), S. 123-127 
    Details
    ISSN: 1573-739X
    Keywords: Catalysis ; Drug stability ; Mitomycins ; Reaction kinetics ; Reaction mechanisms ; Stereoisomers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The acid-catalyzed degradation of mitomycin C is supposed to be governed, to a certain extent, by the protonation status of the aziridine nitrogen in the molecule as well as the protonation degree of the opened aziridine function in a key intermediate species, formed during mitomycin degradation. In order to obtain information about the contribution of the protonation degrees of these functions in controlling the degradation processes, we investigated the degradation of 1a-acetylmitomycin C in acidic aqueous solutions. In the presence of 0.001 mol/l phosphate buffers five 1-hydroxy and mono-acetyl mitosenes are formed, whereas in 1.0 mol/l acetate buffers a total of eight products could be identified, two of them being diacetyl mitosenes. Over the whole pH range studied the formation of 1,2-Z-mitosenes prevails, indicating that, contrary tomitomycin C, a pH-independent factor controls the ultimate 1,2-stereochemistry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02113940
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  • 17
    Electronic Resource
    Electronic Resource
    Measurement and verification of rates of sediment phosphorus release for a hypereutrophic urban lake (1993)
    Springer
    Hydrobiologia 253 (1993), S. 301-309 
    Details
    ISSN: 1573-5117
    Keywords: Phosphorus ; sediment ; lakes ; eutrophication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The contribution of sediment release to the phosphorus budget of hypereutrophic Onondaga Lake was determined through laboratory measurements made on intact cores. Rates ranged from 9–21 mg P m−2 d−1 with a mean of 13 mg P m−2 d−1, values similar to those observed in other lakes of comparable trophic state. There was no statistically significant trend in rates in time (July versus September) or in space (location along the major N/S axis of the lake). Rates of sediment phosphorus release measured in the laboratory compared favorably with the observed rate of soluble reactive phosphorus accumulation in the lake's hypolimnion. The sediments are the second largest source of phosphorus for Onondaga Lake, contributing 24% of the overall phosphorus load to the system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00050750
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  • 18
    Electronic Resource
    Electronic Resource
    Optimization in organic synthesis. An approach to obtaining kinetic information by sequential response surface modelling. Outline of the principles (1993)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 7 (1993), S. 341-367 
    Details
    ISSN: 0886-9383
    Keywords: Reaction kinetics ; Initial rate ; Kinetic order ; Response surface modelling ; Canonical analysis ; Organic synthesis ; Optimization ; Reaction mechanisms ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is presented by which it is possible to estimate the initial rate of chemical reactions when the experimental conditions are varied according to a response surface design. The method is intended as a complementary method for analysing data obtained from experiments in synthetic chemistry when the objective is to optimize the yield of the reaction.Data obtained by simulations have been used to develop the method. From the simulated reactions it is shown that sequential analysis of the chemical yield of the reaction makes it possible to estimate models which describe how the parameters of the response surface of the yield vary over time. The derivatives of these time functions of the response surface parameters can be used to define a rate function which describes how the variations in the experimental conditions influence the rate of the reaction.It is shown how such rate functions can be used to afford reasonable estimates of the initial rates of the reaction. The initial reaction rates thus estimated can be used to determine the kinetic order of the reactants and also to provide estimates of the activation energy of the reaction.A thorough discussion of how canonical analysis of the rate function may assist in the elucidation of reaction mechanisms is given.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180070503
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    Computer-Assisted Solution of Chemical Problems - The Historical Development and the Present State of the Art of a New Discipline of ChemistryDedicated to Professor Karl-Heinz Büchel (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 32 (1993), S. 201-227 
    Details
    ISSN: 0570-0833
    Keywords: Computer chemistry ; Reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The topic of this article is the development and the present state of the art of computer chemistry, the computer-assisted solution of chemical problems. Initially the problems in computer chemistry were confined to structure elucidation on the basis of spectroscopic data, then programs for synthesis design based on libraries of reaction data for relatively narrow classes of target compounds were developed, and now computer programs for the solution of a great variety of chemical problems are available or are under development. Previously it was an achievement when any solution of a chemical problem could be generated by computer assistance. Today, the main task is the efficient, transparent, and non-arbitrary selection of meaningful results from the immense set of potential solutions - that also may contain innovative proposals. Chemistry has two aspects, constitutional chemistry and stereochemistry, which are interrelated, but still require different approaches. As a result, about twenty years ago, an algebraic model of the logical structure of chemistry was presented that consisted of two parts: the constitution-oriented algebra of be- and r-matrices, and the theory of the stereochemistry of the chemical identity group. New chemical definitions, concepts, and perspectives are characteristic of this logic-oriented model, as well as the direct mathematical representation of chemical processes. This model enables the implementation of formal reaction generators that can produce conceivable solutions to chemical problems - including unprecedented solutions - without detailed empirical chemical information. New formal selection procedures for computer-generated chemical information are also possible through the above model. It is expedient to combine these with interactive methods of selection. In this review, the Munich project is presented and discussed in detail. It encompasses the further development and implementation of the mathematical model of the logical structure of chemistry as well as the experimental verification of the computer-generated results. The article concludes with a review of new reactions, reagents, and reaction mechanisms that have been found with the PC-programs IGOR and RAIN.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.199302011
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  • 20
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    Electron Transfer Reactions in Chemistry: Theory and Experiment (Nobel Lecture)Copyright © The Nobel Foundation 1993. - We thank the Nobel Foundation, Stockholm, for permission to print this lecture. (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 32 (1993), S. 1111-1121 
    Details
    ISSN: 0570-0833
    Keywords: Electron transfer ; Reaction mechanisms ; Nobel lecture ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Since the late 1940s, the field of electron transfer processes has grown enormously, both in chemistry and biology. The development of the field, experimentally and theoretically, as well as its relation to the study of other kinds of chemical reactions, presents to us an intriguing history, one in which many threads have been brought together. In this lecture, some history, recent trends, and my own involvement in this research are described.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.199311113
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  • 21
    Electronic Resource
    Electronic Resource
    Pulse radiolysis of aromatic amino acids — State of the art (1992)
    Springer
    Amino acids 2 (1992), S. 195-214 
    Details
    ISSN: 1438-2199
    Keywords: Amino acids ; Pulse radiolysis ; Aromatic amino acids ; Reaction mechanisms ; Free radicals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The pulse radiolysis method as well as the primary processes of water radiolysis and the spectroscopic characteristics of H, OH, HO2/O2 − and e aq - are briefly presented. Subsequently, kinetic and spectroscopic data of the transients resulting from the resolved multi site attack on aromatic amino acids are discussed. The reactivity of H and e aq - with the same substrates, as well as the effect of oxygen on the major radiolytic processes are reviewed. Finally, the formation of tryptophan radical cation is mentioned shortly. The presented radiation mechanisms are the fundamentals for radiolytic processes occurring in proteins, enzymes and hormones in the living cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00805942
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  • 22
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    Chemistry and trophic evolution of Lake Lugano in relation to nutrient budget (1992)
    Springer
    Aquatic sciences 54 (1992), S. 219-237 
    Details
    ISSN: 1420-9055
    Keywords: Eutrophication ; Phosphorus ; Nitrogen ; Lake restoration ; Lake Lugano (Lago di Lugano)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chemical studies performed in the last 50 years on the northern and southern basins of Lago di Lugano are reviewed and discussed in relation to the phosphorus and nitrogen loads from the drainage area. Both basins became eutrophic in the fifties as a consequence of the dense population and industrial activity in the drainage area; the effect of these was aggravated by the meromictic condition of the layer below 100 m in the northern basin. The reduction of phosphorus loads in progress since 1976 has resulted in a significant improvement in the chemical and biological condition of the southern basin and the upper 100 m of water in the northern basin. On the other hand, the balance between dissolved oxygen and reducing substances in the northern basin is shifting toward a decrease of the net oxygen concentration, partly as a consequence of the unusually dry conditions of the last three years. A reduction in phosphorus load down to 18 and 22 t a−1 in the northern and southern basins respectively is still necessary in order to reduce the lake phosphorus concentration to 30–35 µg O l−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00878138
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  • 23
    Electronic Resource
    Electronic Resource
    Effects of leaf longevity and retranslocation efficiency on the retention time of nutrients in the leaf biomass of different woody species (1992)
    Springer
    Oecologia 90 (1992), S. 80-87 
    Details
    ISSN: 1432-1939
    Keywords: Nitrogen ; Phosphorus ; Nutrient use efficiency ; Retranslocation ; Leaf longevity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A study was made of the retention times of N and P in the leaf biomass and their relationship with the retranslocation percentages and the leaf longevities in some woody species in Central Spain. The retention times of both nutrients were strongly related to the nutrient status of each species. These results suggest that a prolonged retention time is a way of increasing nutrient use efficiency in conditions of low nutrient availability. Plants can increase the retention time of nutrients in their leaf biomass by means of an increase in leaf longevity and/or by means of an increase in retranslocation efficiency. However, the effect of the retranslocation efficiency on retention times was almost negligible compared with the effect of leaf longevity. This suggests that an increase in leaf longevity is probably the best adaptation for increasing efficiency in the use of nutrients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317812
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  • 24
    Electronic Resource
    Electronic Resource
    The relationships between soil factors, grass nutrients and the foraging behaviour of wildebeest and zebra (1992)
    Springer
    Oecologia 90 (1992), S. 422-428 
    Details
    ISSN: 1432-1939
    Keywords: Grasses ; Grazing ; Habitat use ; Nitrogen ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We examined the relationships between soil factors, nutrients in grasses and foraging behaviour of wildebeest (Connochaetes taurinus) and zebra (Equus burchelli) in a semi-arid nature reserve in South Africa. We tested the hypotheses that: (1) Soil nutrient levels determine the abundance and distribution of grass species; (2) nutrient levels within grass species are correlated with soil nutrient levels; (3) the spatial distribution and diet composition of ungulates is influenced by the nutrient availability in grasses. The distribution of soil factors in upper ground levels did explain the differential abundance of grass species in the reserve. Ordination of nutrient levels in grass species showed high levels of particular nutrients in certain species, but no one species showed uniformly high levels of all nutrients. Moreover, grasses on fertile soils did not necessarily accumulate higher nutrient levels than grasses on poor soils. Thus, nutrient levels in grasses were not correlated with soil nutrient levels. Wildebeest and zebra responded to monthly variations in the levels of N and P in grasses by moving seasonally to habitat types characterized by grass communities containing a high proportion of nutritional species, rather than by selecting particularly nutritious species within communities. We suggest that within semiarid savannas, areas with a higher diversity of grass communities will be more likely to have some of these communities containing high nutrient levels at any given season, than a lower diversity area. Therefore, the higher-diversity area would be likely to support more herbivores, and thus diversity would control carrying capacity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317701
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  • 25
    Electronic Resource
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    Density dependent interactions between VA mycorrhizal fungi and even-aged seedlings of two perennial Fabaceae species (1992)
    Springer
    Oecologia 91 (1992), S. 281-287 
    Details
    ISSN: 1432-1939
    Keywords: Vesicular-arbuscular mycorrhizas ; Densitydependence ; Plant population dynamics ; Resource depletion ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The interaction of density and mycorrhizal effects on the growth, mineral nutrition and size distribution of seedlings of two perennial members of the Fabaceae was investigated in pot culture. Seedlings of Otholobium hirtum and Aspalathus linearis were grown at densities of 1, 4, 8 and 16 plants per 13-cm pot with or without vesicular-arbuscular (VA) mycorrhizal inoculum for 120 days. Plant mass, relative growth rates, height and leaf number all decreased with increasing plant density. This was ascribed to the decreasing availability of phosphorus per plant as density increased. O. hirtum was highly dependent on mycorrhizas for P uptake but both mycorrhizal and non-mycorrhizal A. linearis seedlings were able to extract soil P with equal ease. Plant size distribution as measured by the coefficient of variation (CV) of shoot mass was greater at higher densities. CVs of mycorrhizal O. hirtum plants were higher than those of non-mycorrhizal plants. CVs of the facultatively mycorrhizal A. linearis were similar for both mycorrhizal and non-mycorrhizal plants. Higher CVs are attributed to resource preemption by larger individuals. Individuals in populations with high CVs will probably survive stress which would result in the extinction of populations with low CVs. Mass of mycorrhizal plants of both species decreased more rapidly with increasing density than did non-mycorrhizal plant mass. It is concluded that the cost of being mycorrhizal increases as plant density increases, while the benefit decreases. The results suggest that mycorrhizas will influence density-dependent population processes of faculative and obligate mycorrhizal species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317797
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  • 26
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    Electronic Resource
    Is long-lived foliage in Picea mariana an adaptation to nutrient-poor conditions? (1992)
    Springer
    Oecologia 91 (1992), S. 184-191 
    Details
    ISSN: 1432-1939
    Keywords: Foliar nutrient retranslocation ; Needle age ; Photosynthesis ; Nitrogen ; Phosphorus ; Respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This study evaluated the contribution of different ages of foliage to the nutrient and carbon balance of black spruce (Picea mariana (Mill.) B.S.P.) from a nutrient-poor peatland in Alberta. Seasonal patterns of foliar nitrogen and phosphorus concentration and content were examined in six needle cohorts up to 10 years old. Trees were treated to simulate excess nutrient deficiency (removal of all one-year-old foliage), nutrient excess (fertilized with 250, 50, 100 kg ha−1 NPK split application in June and July), or left as controls. Gas exchange (net assimilation-Na, stomatal conductance-gs, mesophyll conductance-gm, water-use efficiency-WUE, dark respiration-RS) was measured on six different needle cohorts in several control trees in 1989 and 1990. Nitrogen and phosphorus concentration decreased with needle age. Foliar nutrient concentration fell from April to June and then was stable until September except for the fertilized trees where it increased. There was no evidence of greater than normal retranslocation of nutrients from older needles for defoliated trees or greater than normal nutrient loading in older needles of fertilized trees. NA, gs, gm, WUE, and RS were similar for all needles up to six or eight years old, these older needles having NA of 65% of current needles and similar RS. The results do not support to conclusion that older needles of black spruce are retained as an adaptation to nutrient stress. It does not appear that older needles serve as a nutrient storage site in conditions of excess nutrient availability or a greater than normal nutrient source during times of excess nutrient deficiency. It appears that the maintenance of long-livedfoliage in black spruce does not provide for greater flexibility in tree nutrient allocation. Their contribution to the carbon balance of the tree seems to be sufficient to explain their retention.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317782
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  • 27
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    Exploring the effects of multiple management objectives and exotic species on great lakes food webs and contaminant dynamics (1992)
    Springer
    Environmental management 16 (1992), S. 225-229 
    Details
    ISSN: 1432-1009
    Keywords: Fisheries ; Phosphorus ; Contaminants ; Ecosystem ; Management ; Simulation model ; Great Lakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A simulation model was developed to describe linkages among fish food web, nutrient cycling, and contaminant processes in the southern basin of Lake Michigan. The model was used to examine possible effects of management actions and an exotic zooplankter (Bythotrephes) on Lake Michigan food web and contaminant dynamics. The model predicts that contaminant concentrations in salmonines will decrease by nearly 20% ifBythotrephes successfully establishes itself in the lake. The model suggests that this decrease will result from lowered transfer efficiencies within the food web and increased flux of contaminants to the hypolimnion. The model also indicates that phosphorus management will have little effect on contaminant concentrations in salmonines. The modeling exercise helped identify weaknesses in the data base (e.g., incomplete information on contaminant loadings and on the biomass, production, and ecological efficiencies of dominant organisms) that should be corrected in order to make reliable management decisions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02393827
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  • 28
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    Connatal rickets following repeated administration of phosphate enemas in pregnancy: A case report (1992)
    Springer
    European journal of pediatrics 151 (1992), S. 54-56 
    Details
    ISSN: 1432-1076
    Keywords: Congenital rickets ; Pregnancy ; Phosphorus ; Cathartics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We present a case of antenatal failure of bone growth and mineralisation in a newborn whose anorectic mother repeatedly administered hypertonic phosphate enemas during pregnancy. Phosphate overload in pregnant women appears to impede calcification of the fetal skeleton.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02073893
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  • 29
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    Particulate phosphorus removal via wetland filtration: An examination of potential for hypertrophic lake restoration (1992)
    Springer
    Environmental management 16 (1992), S. 67-74 
    Details
    ISSN: 1432-1009
    Keywords: Restoration ; Wetland ; Lake ; Eutrophication ; Florida ; Phosphorus ; Vollenweider
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Lake Apopka in Florida, USA, is a large (area=124 km2), hypertrophic (mean total phosphorus=0.220 g/m3; mean chlorophylla=60 mg/m3) lake, with a large sedimentary store of available P (1635 × 106 g P). Phosphorus loading from floodplain farms (132 × 106 g P/yr) has been the primary cause of eutrophication. Assuming elimination of farm P loading, the Vollenweider model predicts a decline in equilibrium P concentration from 0.270 to 0.024 g/m3, if the P sedimentation coefficient (σ) remains constant. It is likely, however, that the value for σ will fall with the elimination of farm loading due to unabated internal P loading from the sediments. Under a worst-case scenario (σ=0), the model predicts that exportation of P from the lake via wetland filtration will greatly accelerate the lake's recovery. Recirculation of lake water through a 21-km2, created wetland and elimination of farm P loading is projected to result in a negative P balance for the lake (−23 × 106 g P/yr) leading to depletion of P stores in the lake in about 60 yr. The estimated cost of the project, $20 million, is less than 3% of the estimated cost of dredging. A 3.65-km2 demonstration project is underway to test and refine the wetland filtration technique. We believe the technique could be cost-effective for other hypertrophic lakes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02393909
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  • 30
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    Electronic Resource
    Long term influence of fertilization in a Nardetum (1992)
    Springer
    Plant ecology 103 (1992), S. 151-158 
    Details
    ISSN: 1573-5052
    Keywords: Pasture ; Fertilization experiment ; Permanent plots ; Nitrogen ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An experiment on the very poor alpine pasture, the Geo montani-Nardetum, was started in 1930. Fertilizer was applied in the years 1930–1936 (first treatment) and 1946–50 (second treatment). Until now, the influence of the fertilization is visible in the species composition of the vegetation of the squares, most clearly for the treatments with limestone. The content in N and P of the leaves still varies between the squares with different treatments. Leaves from squares once having received N or P have higher contents in N or P than the others. The pH of the soil is higher in squares treated with limestone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00047702
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    Development of a computer model to predict strains in the individual fibers of a ligament across the ligamentous occipito-atlanto-axial (C0-C1-C2) complex (1992)
    Springer
    Annals of biomedical engineering 20 (1992), S. 667-686 
    Details
    ISSN: 1573-9686
    Keywords: Fibers ; Ligaments ; Computer model ; Strains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract A fresh ligamentous occipito-atlanto-axial (C0-C1-C2) complex was appropriately prepared and serially sectioned into thin slices along the transverse planes. The bony outlines from these slices were digitized and assembled in the proper manner to obtain a three-dimensional model of the complex using the AutoCAD® system. Various ligaments were identified on the model and strains in individual fibers of a ligament were predicted based on the principles of rigid body mechanics. The ligament behaviors in axial rotation, flexion, and extension modes were analyzed. The capsular ligament fibers were predicted to undergo strains in all modes. Furthermore, these ligaments experienced the largest strain among the ligaments analyzed. Fibers within a ligament were found to respond differently; some were more active than the others and some did not experience any strain at all. A differential behavior in the right and left side alar ligament fibers was also found in axial rotation. The transverse ligament was predicted to wrap around the dens during axial rotation. The strain within a fiber was found to be a function of the initial length (ligament laxity) and its distance from the center of rotation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02368612
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  • 32
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    Electronic Resource
    Balance sheet of phosphorus, sulphur and potassium in a long-term grazed pasture supplied with superphosphate (1992)
    Springer
    Nutrient cycling in agroecosystems 31 (1992), S. 51-60 
    Details
    ISSN: 1573-0867
    Keywords: Phosphorus ; sulphur ; potassium ; balance sheet ; nutrient cycling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A balance sheet of P, S and K was constructed for a long-term trial which investigates the effects of three rates of superphosphate (9% P, 11% S) on pasture production on border-strip irrigated land grazed with sheep. A balance sheet of the inputs and outputs of P, S and K to the trial over a 38 year period showed that of the nutrients applied in fertiliser, only 51–59% of the P and 15–31% of the S were retained in the soil. Small amounts were lost in animal products (4–19% of the applied nutrients) but major losses were attributed to runoff of P as particulate matter (dung and soil particles) during irrigation and leaching of sulphate-S during irrigation. Losses of K from the site were small and had no effect on total soil K content. The distribution of soil nutrients across the border-strips was also investigated. The results showed that the concentrations of total soil P and S and exchangeable K were significantly greater at the sides of the irrigation borders than in the main strip area of pasture. This was caused by deposition of a disproportionate amount of dung and urine (and therefore nutrients) on the levees where the sheep tended to camp. It was calculated that with increasing superphosphate rates greater amounts of P were transferred to the levees due to the increased amounts of P being recycled via the animals (as a result of increased herbage P concentration, pasture production and stocking rate).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01064227
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  • 33
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    Electronic Resource
    Whole-stream phosphorus release studies: variation in uptake length with initial phosphorus concentration (1992)
    Springer
    Hydrobiologia 235-236 (1992), S. 573-584 
    Details
    ISSN: 1573-5117
    Keywords: Phosphorus ; uptake length ; sediment ; flow injection analysis ; stream ; Australia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new dual channel flow injection analyser that can simultaneously analyse soluble reactive phosphorus and bromide in the field, has been used in an experiment to test the hypothesis that the phosphorus uptake length in Myrtle Creek, a small forested stream in the Australian Highlands, is influenced by the initial phosphorus concentration used in whole-stream release studies. The phosphorus uptake length was found to decrease with decreasing initial phosphorus concentration added; the uptake length was 98 m when an initial P concentration of 51.0 µg 1−1 was used, 90 m with 21.7 µg 1−1 and 63 m with 12.7 µg 1−1. The estimated errors in the uptake lengths were 6–8%. Approximately 32% of the added phosphorus was retained in the 32 m study reach, with almost all (ca. 93%) of this retained phosphorus taken up by the sediments (microbial uptake plus physico-chemical adsorption) and only a small amount retained in transient storage zones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00026245
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    The phytoplankton of Lake Liddell, New South Wales: chlorophyll a concentrations, species seasonal succession, and covariation with nutrients (1992)
    Springer
    Hydrobiologia 245 (1992), S. 41-52 
    Details
    ISSN: 1573-5117
    Keywords: Nitrogen ; Phosphorus ; chlorophyll a ; phytoplankton ; trophic state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Samples of the phytoplankton in a freshwater lake, Lake Liddell, New South Wales (Lat: 32° 22′ S, Long. 150° 1′ E) were collected every 4 weeks between October 1987 and November 1988. Chlorophyll a concentrations ranged from 1.8 μg 1−1 to 9.1 μg 1−1 and were positively correlated with the following nutrient parameters: total and nett mass additions of nitrate/nitrite-N and total-N, total additions of Kjeldahl-N, and nett mass addition N-P ratios. There was no correlation between lake nutrient concentrations and chlorophyll a. Factors other than nutrient concentrations appeared to be effecting chlorophyll a concentrations as summer levels were low despite nutrient concentrations being at a maximum. In spring and summer the phytoplankton was dominated by chlorophytes, with dinoflagellates and diatoms most abundant in autumn. During winter cyanobacteria were the most abundant. The relative abundance of chlorophytes was positively correlated with in lake nitrate/nitrite-N concentrations whereas the relative abundance of cyanobacteria was negatively correlated with this parameter. Based on chlorophyll a concentrations and the phytoplankton flora Lake Liddell can be classified as mesotrophic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00008727
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  • 35
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    Accumulation of calcium and phosphorus in pigeon (Columba livia) embryos (1992)
    Springer
    Journal of comparative physiology 162 (1992), S. 535-538 
    Details
    ISSN: 1432-136X
    Keywords: Embryo ; Calcium ; Phosphorus ; Altricial ; Pigeon, Columba livia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Calcium and phosphorus were measured in the yolk and albumen of fertile pigeon (Columba livia) eggs incubated for 0–17 days, and in embryos and hatchlings. Shell provided most of the calcium for skeletal mineralization of the embryos, whereas phosphorus was derived from the yolk and albumen. Mobilization of calcium from the shell to the embryo commenced at approximately day 11 of incubation, accumulating both in the embryo and the yolk sac. There was 1.4 times more calcium in squab yolk sacs than that contained in newly laid egg yolks. The results suggest that whereas general patterns of calcium and phosphorus accumulation during embryogenesis in altricial birds closely resemble those of precocial birds, calcium mobilization from the shell begins later, proceeds at a slower rate and results in a less mineralized hatchling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00264814
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  • 36
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    Effects of dietary calcium, magnesium and phosphorus on the formation of struvite stones in the urinary tract of rats (1991)
    Springer
    Urological research 19 (1991), S. 305-308 
    Details
    ISSN: 1434-0879
    Keywords: Diet ; Calcium ; Magnesium ; Phosphorus ; Struvite stones ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary After feeding various diets we studied the effects of dietary calcium, magnesium and phosphorus on the formation of struvite stones in rats with urinary tract infections, and also studied the effects of the administration of vitamin D3 and aluminium gel on stone formation. A low-magnesium diet decreased urinary magnesium and prevented stone formation, but a medium-calcium diet did not significantly decrease stone weight. A high-calcium diet decreased urinary phosphorus and inhibited stone formation. A high-calcium and high-phosphorus diet decreased urinary excretion of magnesium and inhibited stone formation. Although the administration of vitamin D3 did not inhibit stone formation, aluminium gel decreased the urinary level of phosphorus and prevented stone formation. A marked decrease in urinary magnesium and/or phosphorus may prevent struvite stone formation in rats with urinary tract infections.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00299065
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  • 37
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    Density-dependent response to mycorrhizal infection in Abutilon theophrasti Medic (1991)
    Springer
    Oecologia 85 (1991), S. 389-395 
    Details
    ISSN: 1432-1939
    Keywords: Mycorrhizal dependency ; Density-dependence ; Root density ; Abutilon theophrasti ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary One purpose of this study was to determine whether an increase in plant density would result in a decrease in response to mycorrhizal infection (particularly as measured by phosphorus content). Increases in plant density generally result in increases in root density in the volume of soil occupied by the plants. Root density, in turn, largely determines phosphorus uptake. If mycorrhizal plants had significantly higher effective root densities than non-mycorrhizal plants due to the fungal hyphae and thus were more thorough in exploiting a given volume of soil for phosphorus, then a given increase in root density might result in a greater proportional increase in phosphorus uptake for non-mycorrhizal plants than for mycorrhizal plants. Two experiments were performed in which mycorrhizal infection and available soil volume per plant were manipulated; one in which the number of plants within a given pot size was varied (experiment 1), and another in which single plants were grown in pots of differing volume (experiment 2). The two experiments yielded similar results but for apparently different reasons. In the first experiment, for a given increase in root density, non-mycorrhizal plants had a greater proportional increase in phosphorus uptake than mycorrhizal plants. Thus, as predicted, response to mycorrhizal infection was greatest at the lowest planting density (highest available soil volume per plant, lowest root density). In experiment 2, response to infection was also greatest at the highest available soil volume per plant (largest pot), but pot size did not influence root density. These results show that the benefit from mycorrhizal infection may be partly determined by root density and they suggest that plants either occurring in patches of contrasting root density in a given community, or occurring in different communities with inherently different root densities may differ in their reliance upon mycorrhizal fungi for phosphorus uptake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00320615
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    Water-quality effectiveness of a detention/wetland treatment system and its effect on an urban lake (1991)
    Springer
    Environmental management 15 (1991), S. 131-138 
    Details
    ISSN: 1432-1009
    Keywords: Lake management ; Phosphorus ; Water quality ; Watershed treatment systems ; Wetlands ; Ponds ; Minnesota ; Urban runoff
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A newly installed combined detention/wetland stormwater treatment facility upstream from Lake McCarrons, Roseville, Minnesota, was monitored for 21 months to evaluate its effectiveness and the response of the lake to decreased phosphorus loads. The treatment facility consists of a 1.0-ha detention pond that discharges into a series of six constructed wetland “chambers.” Data from snowmelt and rainfall events are presented for several pollutants. Results show good reductions for most pollutants. Discussion on the facets of the system's operation are presented. Data from the lake show very little change in its water quality from three years prior to restoration (1984–1986) to three years following restoration (1987–1989): the lake's phosphorus and chlorophyll has actually increased.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02393844
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  • 39
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    Usefulness of natural regions for lake management: Analysis of variation among lakes in northwestern Wisconsin, USA (1991)
    Springer
    Environmental management 15 (1991), S. 281-293 
    Details
    ISSN: 1432-1009
    Keywords: Phosphorus ; Eutrophication ; Lake management ; Water quality ; Regionalization ; Ecoregions ; GIS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A map of summer total phosphorus in lakes was compiled recently for a three-state area of the upper Midwest for purposes of identifying regional patterns of total phosphorus in lakes and attainable lake trophic state. Spatial patterns in total phosphorus from approximately 3000 lakes were studied in conjunction with maps of geographic characteristics that tend to affect phosphorus balance in lakes to identify regions of similarity in phosphorus concentrations in lakes or similarity in the mosaic of values as compared to adjacent areas. While degrees of relative homogeneity are apparent at many scales, the map was designed at a scale that would yield regions with sufficient homogeneity to be useful for lake management throughout the area. In this study, data from 210 lakes in a 1560-mi2 area in northwestern Wisconsin, sampled by the Wisconsin Department of Natural Resources in the spring of 1988 (subsequent to the compilation of the phosphorus map), were examined to: (1) substantiate the existence of the regions depicted on the map in northwest Wisconsin, (2) determine the nature and relative precision of the regional boundaries, (3) determine the relative importance of natural and anthropogenic watershed characteristics, lake types, lake area, and lake depth in explaining within-region differences in lake phosphorus, and (4) demonstrate how the regions might be used by local lake managers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02393860
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  • 40
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    Comparative effects of Glomus mosseae and P fertilizer on foliar mineral composition of Acacia senegal seedlings inoculated with Rhizobium (1991)
    Springer
    Mycorrhiza 1 (1991), S. 35-38 
    Details
    ISSN: 1432-1890
    Keywords: Acacia ; Glomus ; Rhizobium ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A factorial experiment with two controlled factors was conducted in the greenhouse with Acacia Senegal seedlings. The substrate was a degraded sandy soil (Dior soil) poor in available P (11 ppm — Olsen). The first controlled factor was soil sterilization, with two levels: (A) sterilized soil; (B) non-sterilized soil. The second factor was fertilization, with six levels: (1) uninoculated control; (2) inoculation with Rhizobium (ORS 1007); (3) inoculation with Glomus mosseae; (4) double inoculation with ORS 1007 and G. mosseae; (5) inoculation with ORS 1007 and 30 ppm phosphorus per plant; (6) inoculation with ORS 1007 and 60 ppm phosphours. The combination of the two factors and their levels led to 12 different plant treatments (A1–A6 and B1–B6). Compared to the control B1, the B5 and B6 treatments containing phosphorus increased: nodule dry weight about 7 times ; leaf dry weight about 4 times ; total N, P and Mg 4–5 times; total K and Ca 3–4 times. The mycorrhizal inoculation had the same positive effect on plant growth and mineral composition but with lower values. Plants inoculated with Rhizobium alone gave the lowest results. The A1 treatment gave lower values than B1. Foliar mineral contents varied within a narrow range (20–30%).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00205900
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  • 41
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    Patterns of mobilization of calcium, magnesium, and phosphorus by embryonic yellow-headed blackbirds(Xanthocephalus xanthocephalus) (1991)
    Springer
    Journal of comparative physiology 160 (1991), S. 649-654 
    Details
    ISSN: 1432-136X
    Keywords: Aves ; Calcium ; Embryo ; Growth ; Magnesium ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Embryonic blackbirds(Xanthocephalus xanthocephalus) obtain most of their calcium from the eggshell (85 90%), but all of their phosphorus comes from reserves in the yolk (80–85%) and albumen (15–20%). Approximately equal amounts of magnesium are supplied by the eggshell, the yolk, and the albumen. Yolk is depleted of magnesium and phosphorus during embryogenesis, but excess calcium absorbed from the eggeshell is stored in the yolk. Consequently reserves of calcium in the yolk actually increase 8-fold during embryonic development. Our results reveal that altricial birds manifest patterns of mobilization and deposition of calcium and other elements similar to those described for precocial species. Evolution of altriciality from precocity evidently did not entail major changes in how embryonic birds meet the challenge of obtaining the calcium, magnesium, and phosphorus required for development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00571263
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  • 42
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    Design of high-capacity, reversible polymeric adsorbents for acidic gases (1991)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 2 (1991), S. 87-91 
    Details
    ISSN: 1042-7147
    Keywords: Adsorption of CO2 and SOx ; Polyamines ; High Capacity ; Reversible ; Fibers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Polyethyleneimine (PEIM) samples crosslinked by a commercial epoxy resin (Epon 828) were prepared, and their adsorption capacity for acidic gases was studied. The swelling and deswelling characteristics of the crosslinked samples were also examined as part of this program. Reactivation of these adsorbents could be carried out by heat, or by a combination of heat and treatment in dilute alkalies.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pat.1991.220020206
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  • 43
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    Zum oxydativen Abbau von elementarem Phosphor, P4, mit CCl4 und 1,2-Dinucleophilen (1991)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 606 (1991), S. 219-227 
    Details
    ISSN: 0044-2313
    Keywords: Phosphorus ; oxidative degradation ; triethylammonium tris(o-phenylenedioxo)phosphate ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Oxidative Degradation of Elemental Phosphorus, P4, with CCl4 and 1.2-DinucleophilesIn the presence of tertiary amins the interaction of elemental phosphorus with CCl4 and bifunctionally protic nucleophiles such as 1.2-dioles, pyrocatechol, and 2-aminoalcohols leads to an oxidative degradation of P4. Depending on the reaction conditions acyclic as well as cyclic and even spirocyclic phosphorus(III) and phosphorus(V) compounds are obtained in variable proportions. The formation of the phosphorus(V) spiro compounds exclusively occurs by oxidizing spirocyclic phosphorus(III) compounds in the way of the Atherton-Todd reaction. A procedure for preparing triethylammonium tris(o-phenylenedioxo)phosphate, 8, directly from P4, CCl4, and pyrocatechol is given.
    Notes: Farbloser Phosphor, P4, wird in Gegenwart eines tertiären Amins auch durch Tetrachlormethan und difunktionelle protische Nucleophile wie 1,2-Diole, Brenzcatechol und β-Aminoalkohole oxydativ abgebaut. In Abhängigkeit von der Reaktionsführung und der Art und Konzentration des eingesetzten Nucleophils werden sowohl acyclische als auch cyclische und sogar spirocyclische Phosphor(III)- und Phosphor(V)-Verbindungen in unterschiedlichen Mengenverhältnissen erhalten. Die Bildung der Phosphor(V)-Spiroverbindungen erfolgt ausschließlich durch Oxydation spirocyclischer Phosphor(III)-Verbindungen im Sinne einer Atherton-Todd-Reaktion. Für Triethylammonium-tris(o-phenylendioxy)phosphat, 8, wird eine Direktsynthese aus P4, CCl4 und Brenzcatechol angegeben.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19916060123
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    Enantioselective Addition of Organometallic Reagents to Carbonyl Compounds: Chirality Transfer, Multiplication, and AmplificationParts of this review were presented by R. N. during his Merck-Schuchardt lecture series in the Federal Republic of Germany in May 1989. Ar represents aryl substituents in this article. (1991)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 30 (1991), S. 49-69 
    Details
    ISSN: 0570-0833
    Keywords: Chirality transfer ; Carbonyl compounds ; Addition ; Enantioselectivity ; Synthetic methods ; Alcohols ; Reaction mechanisms ; Catalysis ; Alkylation ; Organometallic compounds ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nucleophilic addition of organometallic reagents to carbonyl substrates constitutes one of the most fundamental operations in organic synthesis. Modification of the organometallic compounds by chiral, nonracemic auxiliaries offers a general opportunity to create optically active alcohols, and the catalytic version in particular provides maximum synthetic efficiency. The use of organozinc chemistry, unlike conventional organolithium or -magnesium chemistry, has realized an ideal catalytic enantioselective alkylation of aldehydes leading to a diverse array of secondary alcohols of high optical purity. A combination of dialkylzinc compounds and certain sterically constrained β-dialkylamino alcohols, such as (-)-3-exo-dimethylaminoiso- borneol [(-)-DAIB], as chiral inducers affords the best result (up to 99% ee). The alkyl transfer reaction occurs via a dinuclear Zn complex containing a chiral amino alkoxide, an aldehyde ligand, and three alkyl groups. The chiral multiplication method exhibits enormous chiral amplification: a high level of enantioselection (up to 98%) is attainable by use of DAIB in 14% ee. This unusual nonlinear effect is a result of a marked difference in chemical properties of the diastereomeric (homochiral and heterochiral) dinuclear complexes formed from the dialkylzinc and the DAIB auxiliary. This phenomenon may be the beginning of a new generation of enantioselective organic reactions.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.199100491
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  • 45
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    The Isoinversion Principle - a General Model of Chemical SelectivityDedicated to Vladimir Prelog and to the memory of Horst Pracejus (1991)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 30 (1991), S. 477-515 
    Details
    ISSN: 0570-0833
    Keywords: Selectivity ; Isoinversion principle ; Reaction mechanisms ; Stereoselectivity ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A large number of successful methods for chirality transfer, using either stoichiometric or catalytic chiral auxiliaries, are in use today. However, there is a lack of practical and dynamic selectivity models, i.e. models which take into account the entire reaction sequence, and which allow simple and reliable assessment, optimization and prediction of selectivity in asymmetric syntheses. The models that are available are either too strongly biased to the steric requirement of the particular molecules reacting, but do not go beyond classical considerations of static facial differentiation, or they take a demanding, theoretical approach, which because of its inherent limitations and the great theoretical effort required has not yet found its way into the practical world of the synthetic chemist. The “Isoinversion Principle”, developed on the basis of Eyring's theory, closes this gap. With its aid, the synthetic chemist can determine the characteristic isoinversion temperature Ti for the reaction type of interest from a few temperature-dependent measurements of selectivity parameters. Ti then affords information on interesting questions such as optimization etc. The advantage of this method is that it is useful not only for stereoselectivity, but for any kind of process where selectivity in general (regio-,chemo-, etc) is generated at two or more stages of a reaction sequence, regardless of whether these reactions involve the ground state or a diabatic photoprocess. The present review will demonstrate that this generation of selectivity at two or more stages of a reaction sequence occurs more commonly than is generally thought.
    Additional Material: 52 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.199104771
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    Spectroscopy of Fluid Phases - The Study of Chemical Reactions and Equilibria up to High Pressures (1991)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 30 (1991), S. 641-653 
    Details
    ISSN: 0570-0833
    Keywords: Reaction mechanisms ; Spectroscopy ; Equilibria ; High-pressure chemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The properties of fluid phases can be altered considerably by the external conditions. Phase equilibria and chemical equilibria can be greatly affected, and it is possible to carry out chemical reactions by exploiting the special properties of compressed fluid phases. The use of high pressure in chemical reactions is of considerable diagnostic and preparative value. Applied research is directed towards elucidating the details of existing technical high pressure processes and to the development of novel fluid phase reactions where the application of high pressure is able to induce selectivity. In order to pursue these lines of research, and to study structure and dynamics throughout the entire range from gaseous to liquidlike states, it is important to have spectroscopic methods for characterizing systems at high pressures and temperatures. This article is concerned with quantitative absorption spectroscopy in the infrared to the ultraviolet spectral region at pressures up to about 7 kbar and temperatures up to 900 K.
    Additional Material: 25 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.199106411
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  • 47
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    The Elucidation of Peroxyl Radical Reactions in Aqueous Solution with the Help of Radiation-Chemical MethodsDedicated to Professor Kurt Schaffner on the occasion of his 60th birthday (1991)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 30 (1991), S. 1229-1253 
    Details
    ISSN: 0570-0833
    Keywords: Reaction mechanisms ; Free radicals ; Peroxyl radicals ; Radical reactions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Whenever free radicals are formed, independent of whether this occurs thermally, is induced by UV or ionizing irradiation, or takes place in redox reactions, they are converted rapidly into the corresponding peroxyl radicals in the presence of oxygen. Peroxyl radical reactions in aqueous environments are observed not only in aquatic systems (e.g., rivers, lakes and oceans) but also in the living cell and to a considerable degree even in the atmosphere (in water droplets). The peroxyl radical chemistry occurring in this medium is often very different from that observed in the gas phase or in organic solvents. In spite of the great importance of these reactions in medicine (for example in anti-cancer irradiation therapy and ischaemia) there have been comparatively few studies of peroxyl reactions in aqueous media. Radiation-chemical techniques such as pulse radiolysis offer the best means for carrying out such studies, so that it is not surprising that the majority of the information available in this area has been obtained with the help of radiation-chemical methods. The radiation chemistry of water can be con trolled in such a manner that the main products are ·OH radicals (90 % yield), which react with substrate molecules to give substrate radicals and in the presence of oxygen to give substrate peroxyl radicals. The experimental conditions can also be varied in such a way that HO2·/O2·⊖ radicals can be formed in 100 % yield and caused to react with substrates. We therefore have a simple access to these intermediates, which are extremely important in biological systems. A detailed product analysis, supported by kinetic studies carried out with the help of pulse radiolysis, has been used to clarify the chemistry of a series of peroxyl radicals, so that sufficient material is now available to justify a review of the variety of the peroxyl radical reactions studied by means of radiation-chemical methods. A more general survey of the physical properties of the peroxyl radicals and their unimolecular and bimolecular reactions will be followed by a discussion of selected examples of various classes of substance. Because of the great biological importance of radical-induced DNA damage this area will also be treated briefly.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.199112291
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  • 48
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    Influence of vesicular-arbuscular mycorrhizae on phosphate fertilizer efficiency in two tropical acid soils planted with micropropagated oil palm (Elaeis guineensis jacq.) (1990)
    Springer
    Biology and fertility of soils 9 (1990), S. 43-48 
    Details
    ISSN: 1432-0789
    Keywords: Vesicular-arbuscular mycorrhizae ; Fertilizers ; Phosphorus ; Acid soils ; Oil palm ; Elaeis guineensis ; Glomus spp.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The influence of vesicular-arbuscular mycorrhizae on the efficiency of triple superphosphate and rock phosphate fertilizers was compared in two tropical, acid, P-fixing soils (Ivory Coast) in which the available P was labelled with 32PO inf4 sup3- . Both soils were planted with micropropagated oil palms. The growth reponses to the fertilizer applications were low unless accompanied by VAM inoculation, but both fertilizers were equally available to plants. Isotopic-dilution kinetics analyses indicated that the rock phosphate was solubilized in both soils and there was an enrichment of the labile pool of plant-available P, similar to that with superphosphate. The specific activity and the fraction of P derived from either fertilizer was similar in both mycorrhizal and non-mycorrhizal plants, showing that both absorbed P from the same labile pool of P in the fertilized soils. However, VAM inoculation increased the fertilizer utilization coefficient of plants 2.7- to 5.6-fold, depending on the soil and fertilizer. We conclude that VAM inoculation increases fertilizer efficiency, as much of rock phosphate as of superphosphate, for plants growing in acid, P-fixing soils, and the processes involved are not different for the two fertilizers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335860
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    The effects of phosphate supply on growth of plants from the Brasilian Cerrado: experiments with seedlings of the annual weed, Bidens gardneri Baker (Compositeae) and the tree, Qualea grandiflora (Mart.) (Vochysiaceae) (1990)
    Springer
    Oecologia 82 (1990), S. 81-86 
    Details
    ISSN: 1432-1939
    Keywords: Qualea grandiflora ; Bidens gardneri ; Cerrado ; Mineral nutrition ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Plants of the cerrado tree species Qualea grandiflora and the annual herb Bidens gardneri were grown from seed in controlled environment rooms at 30/20° C and 12 hour photoperiod. Seedlings were grown in pots or small tubes containing sand and provided with various amounts of mineral solutions based on the formulation of Hoagland and Arnon but with the phosphate content modified in some cases. In a long-term experiment lasting 213 days, plants supplied with full strength Hoagland's solution all died but plants of Qualea given 1/10 strength solution survived, although they grew very slowly. Low relative growth rates (0.008–0.036 d−1) were also a feature of other experiments with Qualea and calculated rates of net assimilation rate gave values of 3–7 mg CO2 dm−2 h−1. Expansion of the photosynthetic surface proceeded slowly and the cotyledons were the main site of photosynthesis for more than 40 days. The low rates of growth occurred despite significant uptake of phosphorus by young plants and in shortterm experiments growth was independent of the amount of phosphate supplied and accumulated. In contrast, the values of R found for plants of Bidens reached 0.24 d−1. Growth of young plants was dependent on the external supply of phosphorus, being reduced when this was low and also when it was very high. Growth of the photosynthetic surface was also much more rapid than for Qualea and also varied with supply of phosphorus. The results are discussed in the context of the occurrence of these species in the Cerrado.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318536
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  • 50
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    Rapid cycling of nitrogen and phosphorus from dying roots of Lolium perenne (1990)
    Springer
    Oecologia 82 (1990), S. 432-436 
    Details
    ISSN: 1432-1939
    Keywords: Grass ; Lolium perenne ; Nutrient cycling ; Phosphorus ; Roots
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Previous experiments, using 32P pulse labelling, showed that when roots of Lolium perenne were detached from the shoot, a substantial proportion of the phosphorus in the roots could within a few weeks be released and be captured by another, living plant. This paper describes experiments designed to confirm and further investigate this rapid nutrient transfer. Roots from plants grown with ample N and P were detached and placed in litter bags in soil. They lost up to 60% of their initial N and up to 70% of their P in three weeks. Even when roots were grown with deficient P supply, resulting in C:P ratios of 300–400, they lost 20–30% of their initial P. Time-courses of 32P loss from roots suspended in solution gave results which agreed with these figures. The initially rapid rate of 32P loss had declined greatly within three weeks. In a pot experiment small L. perenne plants showed a marked increase in their N and P content during 30 days after a neighbouring large plant's shoot was removed, supporting rapid capture of nutrients lost from the detached roots. To investigate P loss from roots while attached to the shoot, L. perenne shoots were clipped every four days and 32P loss from the roots measured. After the third clip the rate of loss increased, eventually to more than four times that from the control plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00319782
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    Rapid loss of phosphorus from dying ryegrass roots: the chemical components involved (1990)
    Springer
    Oecologia 84 (1990), S. 359-361 
    Details
    ISSN: 1432-1939
    Keywords: Nutrient cycling ; Phosphorus ; Roots ; Ryegrass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Lolium perenne was grown in solution culture with either ample or deficient phosphate supply (‘high-P’ and ‘low-P’ plants). The concentration in the roots of phosphorus as water-soluble compounds, phospholipid and insoluble residue was measured. A supplementary experiment showed that the concentration of each component in the roots of low-P plants was similar to that in plants grown in P-deficient soil. The time-course of the decline of each P component was determined in roots detached from the shoot and left hanging in solution. During the three weeks residue P concentration in the roots declined little. In contrast, both types of root lost about three-quarters of their lipid P in the first week. Low-P roots lost little of their water-soluble P. High-P roots contained much more water-soluble P and lost much of it during the first two weeks. By the end of three weeks their water-soluble P content was levelling out at a value similar to that in low-P roots, suggesting a ‘non-labile pool’. The rapid loss of lipid P from low-P roots comprised more than half of their total loss, and the possible ecological significance of this is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00329759
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    Occurrence of bombesin-like immunoreactivity in the brain of the cartilaginous fish,Scyliorhinus canicula (1990)
    Springer
    Cell & tissue research 259 (1990), S. 177-181 
    Details
    ISSN: 1432-0878
    Keywords: Bombesin-like peptide ; Immunocytochemistry ; Hypothalamus ; Neurosecretory ; Fibers ; Scyliorhinus canicula (Elasmobranchii)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The presence and distribution of bombesin-like material were investigated in the brain of the cartilaginous fishScyliorhinus canicula using conventional immunocytochemical techniques. Perikarya containing bombesin-like immunoreactivity were identified in the hypothalamus, within the magnocellular component of the preoptic nucleus. Some immunopositive elements appeared to be of cerebrospinal fluid-contacting type. Beaded immunoreactive fibers were seen crossing the ventral telencephalon and the whole hypothalamus. An important tract of fibers was found in the infundibular floor and in the median eminence, in close contact with the vascular system of the pituitary portal plexus. A moderate number of positive fibers innervated the habenular complex and the dorsal wall of the posterior tuberculum. These findings indicate that a neuropeptide strictly related to amphibian bombesin is located in specific hypothalamic neurons ofS. canicula. The distribution of the immunoreactive fibers and terminals suggests that, in fish, this peptide, may be involved in neuroendocrine and neuromodulator functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00571441
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    SAXS experiments on gel-spun polyethylene fibers (1990)
    Springer
    Colloid & polymer science 268 (1990), S. 245-255 
    Details
    ISSN: 1435-1536
    Keywords: Fibers ; polyethylene ; gel-spinning ; smallanglex-rayscattering ; spinningconditions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The properties of gel-spun polyethylene fibers hot-drawn to the maximum draw ratio depend on the spinning conditions. Different spinning conditions result in two types of structure in the paraffin oil containing fibers: an isotropic lamellar structure or a shish-kebab structure. Meridional SAXS experiments can identify the structure present. After extraction, these structures are still present but can be detected only in a more indirect way by SAXS experiments because of an excessive contribution of void scattering. During hot-drawing both structures are transformed into a more fibrillar structure. The shish-kebab structures can be drawn only to relatively low hot-draw ratios with an incomplete transformation of the lamellar overgrowth into the fibrils, as demonstrated by the presence of a meridional SAXS maximum/shoulder. This leads to relatively weak fibers. Lamellar structures can be drawn to high draw ratios by chain unfolding. A nearly complete transformation of the lamellae into fibrils is obtained and the fibers have excellent properties. The information about the morphology obtained by SAXS, DSC, WAXS, and SEM can be used to establish a relation between morphology and properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01490249
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    Balanced fertilization with particular reference to phosphates: Interaction of phosphorus with other inputs and management practices (1990)
    Springer
    Nutrient cycling in agroecosystems 26 (1990), S. 29-52 
    Details
    ISSN: 1573-0867
    Keywords: Phosphorus ; P-efficient ; P-availability ; P-placement ; P X management interactions ; nutrient balance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphorus interactions with various management practices and inputs are complex and vary from physiological to inorganic in nature. Awareness of these interactions can have significant effects on decisions to apply P, can influence rates of applied P and should be seriously considered in decisions on method of P application. Recognizing that combinations of climatic and tillage system factors can influence short-term P availability may lead to the decision to apply fertilizer P even when soil P tests are high. Nutrient balance is one of the most important factors in P response. The interaction of N, P and K are of special significance, often determining whether responses to additions occur and the extent to which they are efficient and profitable. Phosphorus-micronutrient interactions can have significant effects on plant growth and yield but often are of more academic than practical interest for most crops. Soil testing and plant analysis to detect levels of micronutrient deficiency followed by applications of appropriate amounts of micronutrients can offset detrimental P-micronutrient interactions commonly reported for metals such as Zn, Fe and Cu.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01048742
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  • 55
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    On the Conformation and Structure of Organometal Complexes in the Solid State: Two Studies Relevant to Chemical SynthesisDedicated to Professor Jack Dunitz (1990)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 29 (1990), S. 256-272 
    Details
    ISSN: 0570-0833
    Keywords: Solid-state reactions ; Complexes ; Organometallic compounds ; Conformation analysis ; Reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformational preferences of two classes of organometal complexes have been surveyed by inspecting the Cambridge Structural Database (CSD). Lewis acid carbonyl complexes demonstrate a variety of coordination geometries, depending on the electronic and steric requirements of the carbonyl ligands and the nature of the Lewis acid. Similarly, the solid-state conformation of various π-bonding ligands in metal acyl, metal nitrosyl, metal acetylene, and metal imido complexes is revealed. These insights have stimulated the development of a conformational model that is based on considerations of π-bond hybridization and frontier molecular orbital theory. The analyses are relevant to the mechanism and transition structures of many synthetically important transformations. A deeper understanding of the conformational properties of organometal complexes, based on accurate structural information, will likely expedite the design and improvement of metal-mediated processes.
    Additional Material: 49 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.199002561
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    Elementary Steps in Heterogeneous CatalysisFrom a paper presented at the awarding of the A-Mittasch Medal during a colloquium celebrating the 125th. anniversary of the founding of BASF on September 24, 1990 in Ludwigshafen (FRG). (1990)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 29 (1990), S. 1219-1227 
    Details
    ISSN: 0570-0833
    Keywords: Heterogeneous catalysis ; Reaction mechanisms ; Catalysis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Despite the great importance of heterogeneous catalysis, research in this field has long been characterized by its empiricism. Now, however, thanks to the rapid development of methods in surface physics, the elementary steps can be identified at the atomic level and the underlying principles understood. Defined single crystal surfaces are employed as models, based on the analysis of the surfaces of ‘real’ catalysts. Direct images, with atomic resolution, can be obtained using scanning tunneling microscopy, while electron spectroscopic methods yield detailed information on the bonding state of adsorbed species and the influence of catalyst additives (promotors) upon them. The successful application of this approach is illustrated with reference to the elucidation of the mechanism of ammonia synthesis. The catalyst surface is usually transformed under reaction conditions, and, as the processes involved are far-removed from equilibrium, such transformations can lead to intrinsic spatial and temporal self-organization phenomena. In this case, the reaction rate may not remain constant under otherwise invariant conditions but will change periodically or exhibit chaotic behavior, with the formation of spatial patterns on the catalyst surface.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.199012191
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    CC Bond Formation by Addition of Carbenium Ions to Alkenes: Kinetics and MechanismDedicated to Professor Rolf Huisgen on the occasion of his 70th birthday (1990)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 29 (1990), S. 1371-1384 
    Details
    ISSN: 0570-0833
    Keywords: Kinetics ; Addition ; Alkenes ; Reaction mechanisms ; Carbocations ; C-C coupling ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The addition of carbenium ions to CC double bonds, a key step in many syntheses in organic and macromolecular chemistry, is analyzed using the Lewis acid promoted reactions of alkyl chlorides with alkenes as an example. Stereochemical and kinetic experiments suggest that the transition state is slightly bridged and product-like. Rearrangements of the carbenium ions that result from the electrophilic attack can be minimized by adding salts with nucleophilic counter ions. The thermodynamics of the addition reactions are analyzed, and the conditions necessary in order to observe the back reaction (i.e. the Grob fragmentation) are discussed. Multiparameter equations that predict rate constants are derived from kinetic studies on the reactivities of carbenium ions and alkenes. Reactivity-selectivity relationships over a reactivity range that covers eight orders of magnitude show that the structure of the transition state is only changed by variation of substituents in the immediate vicinity of the reaction center.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.199013713
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    The Course of the Willgerodt-Kindler Reaction of Alkyl Aryl KetonesA review article (a continuation of [1]) is being prepared in which the new compounds discussed in the present paper are treated in greater detail. A paper recently published [2] prompted us to make our concept of the course of the Willgerodt-Kindler reaction known.Respectfully dedicated to Prof. Dr. Karl Ziegler on the occasion of his 65th birthday (1964)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 19-28 
    Details
    ISSN: 0570-0833
    Keywords: Willgerodt-Kindler reaction ; Ketones ; Reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ketones react with sulfur and NH3 or amines at room temperature to produce Δ3-thiazolines, 5-alkylidene-Δ3-thiazolines, Δ3-imidazoline-5-thiones, hexathiacycloheptane derivatives, α,α′-dioxodisulfides, bis-(1-aralk-1-yl) disulfides, or thiocarboxamides, depending on the coreactant and on the reaction conditions. It was recognized that the formation of all of these numerous types of compounds can be explained basically by primary thiolations and geminal dithiolations, which in conjunction with their reverse reaction (desulfurization) and the assumption of a thioreductone equilibrium permit a new interpretation of the course of the Willgerodt-Kindler reaction of alkyl aryl ketones.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196400191
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    Complexes of Tetradentate Ligands Containing Phosphorus and ArsenicAdapted from a Plenary Lecture at the General Meeting of the Gesellschaft Deutscher Chemiker on Sept. 10th, 1963 in Heidelberg (Germany). (1964)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 453-460 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196404531
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    The Mechanism of the Action of Organometallic CatalystsDedicated to Prof. Dr. Karl Winnacker on the occasion of his 60th birthday. (1964)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 93-101 
    Details
    ISSN: 0570-0833
    Keywords: Organometallic catalysts ; Catalysis ; Reaction mechanisms ; Lithium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Kinetic investigations of the polyreaction of isoprene with organolithium compounds as initiators in n-heptane as solvent indicate the following sequence of reactions: 1. formation of an adduct between a monomeric form of the organolithium compound and the isoprene and 2. reaction of this adduct with an associated form of the organolithium compound with insertion of the isoprene. The adduct formation is considered to be due to chemisorption, and proof of such chemisorption of a monomer (ethylene) is also demonstrated for a homogeneous Ziegler-type catalyst. All the reactions can be formulated in the form of cyclic structures with electron-deficient character. Postulation of such ring structures explains the surprising values obtained for the frequency factors and equilibrium constants.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196400931
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    The Chemistry of New Heat-Resistant Films and Fibers (1964)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 460-470 
    Details
    ISSN: 0570-0833
    Keywords: Heat resistance ; Fibers ; Polymers ; Materials science ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This survey is principally concerned with papers published since 1959 on hydrocarbon polymers, aliphatic poly(terephthalamide) fibers, poly(hydroxybenzoic acid) films, poly(oxadiazole) fibers, poly(benzimidazole) films, poly(phenyltriazole) films, poly(pyromellitimide) films, and fibers from cyclized poly(acrylonitrile). All these materials have extremely high melting points and satisfactory in-use characteristics at high temperatures.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196404601
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    Kinetics and Mechanism of 1,3-Dipolr CycloadditionsExtended version of a lecture given at the Annual Meeting of the Dechema in Frankfurt/Main on June 14th, 1962, and of the Max Tishler Lecture at Harvard University on December 10th, 1962. (1963)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 633-645 
    Details
    ISSN: 0570-0833
    Keywords: Kinetics ; Dipolar cycloaddition ; Cycloaddition ; Heterocycles ; Reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Criteria for the mechanism of 1,3-dipolar cycloadditions which lead to 5-membered rings are provided by the stereoselectivity observed with cis-trans isomeric dipolarophiles, by the effect of solvent and substituents on the rate constants, by the activation parameters, and by orientation phenomena. A concerted addition, which can also be described in terms of molecular orbitals and in which the two new σ-bonds are formed simultaneously, although not necessarily at equal rates, offers the best explanation of the experimental facts.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196306331
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    Phenol Oxidation ReactionsDedicated to Professor Dr. Hans Brockmann on the occasion of his 60th birthday (1963)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 723-735 
    Details
    ISSN: 0570-0833
    Keywords: Phenol oxidation ; C-C coupling ; Reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The use of well-known phenol oxidation reactions for the preparation of compounds arising from C—C and C—O coupling has recently received increased attention. A selection from the large number of products obtainable by oxidation of mono- and polyhydric phenols and a discussion of the reaction mechanisms indicate the scope of this method. The formation of hydroxyphenylquinones and orceine dyes from resorcinol derivatives is explained. The synthesis of natural products by way of phenol oxidations is briefly discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196307231
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    Further Contributions to the Knowledge of SemimetalsDedicated to Dr. W. Foerst on the occasion of his 65th birthday (1963)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 523-530 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196305231
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    New Developments in the Chemistry of PolyphosphanesDedicated to Prof. Dr. Karl Winnacker on the occasion of his 60th birthday (1963)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 646-654 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196306461
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    Oligomers and Pleionomers of Synthetic Fiber-Forming Polymers (1963)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 410-420 
    Details
    ISSN: 0570-0833
    Keywords: Oligomers ; Pleionomers ; Polymers ; Fibers ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The term “oligomer” is defined, and a survey of methods for the isolation and synthesis of cyclic and linear oligoesters, oligourethanes, oligo(acrylonitriles), and oligoamides is presented. The oligomers serve a valuable function as model substances for the investigation of many properties of the corresponding high polymers. This is shown using several examples (infrared spectroscopy, X-ray spectroscopy, viscosity).
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/anie.196304101
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    The Mechanism of Bimolecular β-Elimination ReactionsBased on lectures presented in February-July, 1961, at University College, London, University College, Dublin, the University of Bologna and the University of Munich. (1962)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 225-235 
    Details
    ISSN: 0570-0833
    Keywords: Elimination ; Reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In bimolecular β-elimination (E 2 mechanism), several bonds are ruptured or formed in one concerted reaction step. However, the various aspects of bond-making or -breaking need not be completely synchronous. In the E 2 transition state for elimination HX, rupture of the C—X bond may be more advanced than that of the C—H linkage, or vice versa. Factors influencing the relative extents of rupture of these two bonds at the transition state are discussed, and the consequences of non-synchroneity in one sense or the other are developed from theory and illustrated from experiment. This treatment provides an understanding of the Hofmann-vs.-Saytzeff orientation problem.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196202251
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    Pyrrolidone, Capryllactam and Laurolactam as new Monomers for Polyamide FibersFrom a lecture delivered at the meeting of the Plastics and Rubber Section of the Gesellschaft Deutscher Chemiker on April 9th, 1962, in Bad Nauheim (Germany). (1962)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 430-435 
    Details
    ISSN: 0570-0833
    Keywords: Pyrrolidone ; Polyamides ; Fibers ; Lactams ; Polymerization ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The industrial production of capryllactam (1-azacyclononan-2-one) and of laurolactam (1-azacyclotridecan-2-one) starts with cyclization of acetylene or butadeine to give cyclooctatetraene or cyclooctadiene, or cyclization of butadiene to give cyclododecatriene. Further steps are: oxidation of the cyclic hydrocarbon to the ketone, formation of the oxime, and rearrangement of the latter with sulfuric acid. Pyrrolidone can be prepared from acetylene and formaldehyde by way of butyrolactone. The behavior of the lactams during polycondensation is described and the properties of the resulting fibers are compared with those of the known polyamide fibers.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196204301
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    Isocyanates of Esters of Some Acids of Phosphorus and SilicionDedicated to Prof. Dr. Otto Bayer on the occasion of his 60th birthday (1962)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 617-621 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196206171
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    β-Chloroethylphosphonic Dichloride: Its Synthesis and Use (1962)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 652-656 
    Details
    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.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/anie.196206521
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    Electrophilic Substitutions at Saturated Carbon Atoms (1962)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 382-393 
    Details
    ISSN: 0570-0833
    Keywords: Electrophilic reactions ; Reaction mechanisms ; Substitution ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The results obtained in recent years from investigations into the mechanisms of electrophilic substitution reaction at sp3-hybridized carbon atoms are reviewed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196203821
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    β-Lactams, Their Polymerization and Use as Raw Materials for FibersFrom a lecture delivered on April 9th, 1962 at a meeting of the GDCh-Fachgruppe “Kunstsoffe and Kautschuk” Plastics and Rubber Division of the German Chemical Society in Bad Nauheim. (1962)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 481-488 
    Details
    ISSN: 0570-0833
    Keywords: Lactams ; Polymerization ; Fibers ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: β-Lactams can be prepared by cyclization of β-aimno acid esters. Recently they have become available also from olefins by addition of N-carbonysulfamyl chloride (isocyanatosulfonyl chloride) and from aldehydes by reaction with N-carbonylsulfamyl chloride and ketene. Condensative or anionic polymerization results in polyamides the chains of which contain many more amide groups than the chains of polyamides of the nylon-6 type. Hence the new polymers resemble silk moreclosely. Fibers and films can be prepared from solution.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196204811
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    Dyeing of Poly(acrylonitrile) Fibers with Azatrimethinecyanines (1962)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 532-537 
    Details
    ISSN: 0570-0833
    Keywords: Polyacrylonitrile ; Fibers ; Azatrimethinecyanines ; Dyes/Pigments ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Like all basic dyes, azatrimethinecyanines possess a good dyeing affinity for acrylic fibers. Compounds with isolated nitrogen atoms in the trimethine chain show insufficient light fastness, whereas good to excellent fastness to light is displayed by compounds having neighboring nitrogen atoms in the chain. Thus, a working hypothesis stating that the light fastness of trimethinecyanines on acrylic fibers is improved by progressive replacement of methine groups by nitrogen atoms has been partially confirmed.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196205321
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    Elastomeric Fibers Based on PolyurethanesFrom a report delivered on April 10th, 1962 at the meeting of the GDCh-Fachgruppe “Kunststoffe und Kautschuk” (Plastics and Rubber Group of the German Chemical Society) in Bad Nauheim. (1962)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 419-424 
    Details
    ISSN: 0570-0833
    Keywords: Elastomers ; Fibers ; Polyurethanes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Highly elastic polyurethanes suitable for fiber production can be obtained by various synthetic routes based on diisocyanate polyaddition processes. Macrodiisocyanates obtained from long chain diols and diisocyanates are allowed to react with polyamines during fiber formation (chemical spinning process) or the macrodiisocyanates are treated in solvents (e.g. dimethylformamide) with polyamines to give highly viscous, spinnable solutions of polymer. Both methods yield highly elastic polymers with wide-mesh network structures. The production of polyurethane fibers and their structures and physical properties are described.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196204191
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    Copolymers and Fibers from VinylidenedicarbonitrileLecture at the Meeting of the Gesellschaft Deutscher Chemiker, Section “Kunststoffe und Kautschuk”, on April 10th. 1962 at Bad Nauheim (Germany). (1962)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 425-430 
    Details
    ISSN: 0570-0833
    Keywords: Copolymers ; Fibers ; Vinylidenedicarbonitrile ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Vinyldendicarbonitrile (Vinylidene cyanide) on free redical catalyzed copolymerization shows a much stronger tendency to form 1:1 alternating copolymers than acrylonitrile. While bulk poly(vinylidene cyanide) fails to crystallize, despite its molecular symmetry, several alternating copolymers are readily crystallizable, notably those containing butadiene, isoprene, isobutylene, or vinylidene chloride. Fibers have been prepared from a number of the higher melting copolymers and examined for physical properties. Fibers from the vinyl acetate and vinyl chloride copolymers show expectional elastic behavior both when dry and wet. The fiber from the vinylidene cyanide |vinyl acetate alternating copolymer (Darvan® nytril fiber) is only moderately oriented and is characterized by exceptional softness and excellent elastic recovery and resilience, both when dry and wet.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196204251
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  • 76
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    Electronic Resource
    Long Periods in Drawn PolyethyleneFrom a lecture delivered on Apr. 11th 1962 at the meeting of the GDCh-Fachgruppe “Kunststoffe und Kautschuk” (Plastics and Rubber Division of the German Chemical Society) in Bad Nauheim. (1962)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 488-499 
    Details
    ISSN: 0570-0833
    Keywords: Long periods ; Polyethylene ; Fibers ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Meridional reflections appearing in small-angle X-ray diffraction diagrams of drawn polyethylene are caused by a nearly periodic arrangement of crystalline and disordered regions. The long period, which is determined by the average distance between two consecutive crystallites, depends on the method of preparing the sample. The time and temperature dependences of the positions of the small-angle reflections have been investigated. The growth of the long period of unoriented bulk polyethlene and polyethylene single crystal follows the same time dependence as that of stretched films. However, characteristic differences were obseved in the relationship between density and long period; they are attributed to the fact that in single crystals and in material crystallized from the melt, the chains are folded at the boundaries of the crystallites, whereas this in not the case in stretched polyethylene.
    Additional Material: 25 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196204881
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