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  • Springer  (11)
  • Elsevier  (2)
  • American Association for the Advancement of Science  (1)
  • 1990-1994  (14)
  • 1
    ISSN: 1572-9591
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This paper reports a collaborative effort of a team which formed at Los Alamos to investigate the announcement that “cold fusion” may be occurring in electrochemical cells using palladium cathodes and platinum anodes in a LiOD electrolyte. Four electrochemical cells were construced and operated for 3–5 weeks under various geometrical and electrical conditions. Nuclear diagnostic measurements included high and low resolution gamma-ray spectroscopy, integral neutron counting with well detectors and banks of3He tubes, and neutron spectroscopy withNE-213 scintillators. For one of the cells, the deuterium loading of the cathode was determined from resistance measurements to beD/Pd⩽ 0.8. No conclusive evidence was found for the production of neutrons or 2.223-MeV gammas above levels consistent with background. The results of the measurements of tritium levels in the cell electrolytes are also reported. Experiments to reproduce the observation of neutrons from high pressureTi-D 2 gas experiments were also performed with negative results.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The response of quasi-isotropic laminates of SiC coated carbon/carbon (C/C) composites under flexural load was studied. Mission-cycled as well as virgin specimens were tested to compare the thermal- and pressure-cycling effects. Variation of flexural strength and stiffness with temperature was investigated to study the load-deflection behaviour and the thermal stability of C/C composites up to 1371 °C. Increase in flexural strength and stiffness were observed with the rise in temperature. A distinct shift in failure modes from compressive to tensile was found with the mission-cycled specimens with the increase in test temperatures, while the failure mode for virgin material was found always on the tensile side. Change in the load-deflection behaviour was examined and increase in non-linearity of the stress-strain behaviour with the mission cycling was observed. Although the number of test specimens was few, Weibull characterization on the flexure data was performed to study the variation of Weibull modulii and the characteristic lives. Failed, as well as untested, specimens were C-scanned to identify the location and the extent of the damaged zone. Post-failure analyses through optical microscopy and scanning electron microscopy were performed to study the damage growth and failure mechanisms. Degradation and separation of the porous matrix structure, localized damage of the reinforcing fibres in the transverse direction, complete fibre bundle failure in the mission-cycled specimens, and delamination near the loading zone were observed.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Plant growth regulation 15 (1994), S. 137-141 
    ISSN: 1573-5087
    Keywords: IAA synthesis ; phloem sap ; Ricinus ; tryptophan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The biosynthesis of 14C-IAA from 14C-tryptophan applied to abraded leaves of Ricinus communis and its subsequent export through the phloem were studied. Phloem sap was collected at intervals from incisions made in the stem below the IAA fed leaf. Any upward movement of label through the phloem or downward movement of phloem mobile compounds from leaves above the treated one were restricted by bark-ringing the plants. TLC and HPLC analyses of the collected sap indicate that some conversion of 14C-tryptophan to 14C-IAA had occurred. Subsequent GC-MS analysis of the HPLC purified samples of phloem sap revealed high levels of endogenous IAA transported from the fed leaf. The high ratio of unlabelled/labelled IAA in the phloem sap makes unequivocal confirmation by GC-MS of the predicted biosynthesis of 14C-IAA impossible. It is postulated that IAA is synthesised from tryptophan in mature leaves and exported to developing sink tissues with the flow of photoassimilates in the phloem.
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  • 4
    ISSN: 1573-5044
    Keywords: acylated anthocyanins ; cinnamic acids ; daucus carota (wild carrot) ; flavonoid intermediates ; HPLC separations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Anthocyanins isolated and characterized from the wild carrot suspension cultures used here were 3-O-β-D-glucopyranosyl-(1→6)-[β-D-xylopyranosyl-(1→2)-]β-D〈-galactopyranosylcyanidin (1), 3-O-[β-D- xylopyranosyl-(1→2)-β-D-galactopyranosyl]cyanidin (2), 3-O-(6-O-sinapoyl)-β-D-glucopyranosyl-(1→6)-[β-D- xylopyranosyl-(1→2)-]β-D-galactopyranos ylcyanidin (3), 3-O-(6-O-feruoyl)-β-D-glucopyranosyl-(1→6)-[β- D-xylopyranosyl-(1→2)-]β-D-galactopyranosylcyanidin (4), 3-O-(6-O-coumaroyl)-β-D-glucopyranosyl-(1→6)- [β-D-xylopyranosyl-(1→2)-]β-D-galactopyrano sylcyanidin (5), 3-O-[6-O-(3,4,5-trimethoxycinnamoyl)]-β- D-glucopyranosyl-(1→6)-[β-D-xylopyranosyl-(1→2)-]β-D-galactopyranosylcyanidin (6), 3-O-[6-O-(3,4-dime- thoxycinnamoyl)]-β-D-glucopyranosyl-(1→6)-[β-D-xylopyranosyl-(1→2)-]β-D-galactopyranosylcyanidin (7), 3-O-[(6-O-sinapoyl)-β-D-glucopyranosyl-(1→6)-β-D-galactopyranosyl]cyanidin (8), and 3-O-(β-D-galactopyranosyl)cyanidin (9). Except when cinnamic acids were provided in the culture medium, the major anthocyanin present in the two clones examined was 2. When the naturally occurring and some non-naturally occurring cinnamic acids were provided individually in the medium, 1 and 2 were minor components and the anthocyanin acylated with the supplied cinnamic acid, namely 3, 4, 5, 6, or 7 was the major anthocyanin present in the tissue. When caffeic acid was provided the major anthocyanin in the tissue was 4, thereby suggesting that the caffeic acid was methylated before its use in anthocyanin biosynthesis. Other cinnamic acids supplied had limited effects on the anthocyanins accumulated and appeared not to result in the accumulation of new anthocyanins by the tissue. Thus the tissue can use some but not all analogues of sinapic acid to acylate anthocyanins. Additional anthocyanins were detected in extracts of the wild carrot tissue cultures using mass spectrometry (both MS/MS and HPLC/MS). The additional compounds detected have also been found in cultures of black carrot, an Afghan cultivar of Daucus carota ssp. sativa and the flowers of wild carrot giving no evidence for qualitative differences in the anthocyanins synthesized by subspecies, cell cultures from subspecies, or clones from cell cultures. There are major differences in the amounts of individual anthocyanins found in cultures from different subspecies and in different clones from cell cultures. Here anthocyanins without acyl groups were usually found in the tissues and their accumulation is discussed. On the basis of the structures of the isolated anthocyanins, a likely pathway from cyanidin to the accumulated anthocyanins is proposed and discussed.
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  • 5
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Cation-exchange chromatography ; Organic acids, sugars and alcohol ; Cocoa beans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A cation-exchange HPLC column was evaluated for the analysis of sugars (sucrose, glucose, fructose), acids (citric, lactic and acetic) and ethanol in extracts of cocoa, preserved in a solution of benzoic acid (0,2 % w/v). Optimum sensitivity, precision and selectivity was achieved when the column was operated at a temperature of 25 °C and the combination of a refractive index detector and peak height measured peaks was employed. The limit of detection was 3.5 ng acetic acid, 5.5 ng sucrose, 6.3 ng fructose and lactic acid, 7.3 ng citric acid, 10.5 ng glucose and 12.4 ng ethanol. The extracts of cocoa were stable over a 10 week period, permitting the analysis of large numbers of samples without degradation of the analytes.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 29 (1991), S. 482-488 
    ISSN: 1741-0444
    Keywords: Augmented diffusion ; Finite-difference model ; Gas exchange ; Oxygenator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The goal of this research is to develop a predictive model with good absolute accuracy for blood-gas exchange devices. The proposed model, unlike existing models, is able to predict gas transfer to blood flowing outside oxygenating fibres without experimental data. The proposed model uses a finite-difference numerical technique to solve computationally two-dimensional gas exchange problems such as gas transfer to blood outside hollow fibres. The model is compared to bovine and human experimental data from the small test cells with microporous polypropylene fibres. The test cell flow rates range from 1 m litre min−1 to 5 m litre min−1 for a 72-fibre device. Shear-augmented oxygen diffusion appears to be present, although good accuracy is obtained with a nonaugmented diffusion model, particularly at lower flows. The maximum deviation of oxygen saturation predicted by a shearaugmented bovine blood model from the experimental regression line was 1·7 per cent.
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  • 7
    ISSN: 1615-6102
    Keywords: Casuarina ; Dinitrogen fixation ; Nitrate inhibition ; Actinorhizal ; Nutrient competition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Experiments were conducted to determine the effect on biological dinitrogen fixation byCasuarina of available nitrogen (N) in the substrate and competition by interplantedEucalyptus. In these experiments, combined N was applied to the plants after nodules were developed and functioning. Both environmental factors, nitrate and competition, were observed to influence biological dinitrogen fixation byCasuarina, but not yield (total dry weight). In one experiment, the proportion of nitrogen derived byCasuarina from atmospheric fixation (pNdfa) was observed to be inhibited by potassium nitrate in a linear fashion. However, substrate N did not significantly affect the weight of root nodules. Thus nodule dry weight was not highly correlated with the proportion of nitrogen fixed. In a second experiment, the presence of a non-fixing interplanted species,Eucalyptus, increased dinitrogen fixation inCasuarina.Casuarina interplanted withEucalyptus obtained a greater proportion of its nitrogen (94.75%) from fixation than didCasuarina grown alone (86.68%) suggesting that competition for substrate N influences the proportion of nitrogen fixed by this actinorhizal plant.
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  • 8
    Publication Date: 1993-11-01
    Print ISSN: 0022-2461
    Electronic ISSN: 1573-4803
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Springer
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  • 9
    Publication Date: 1990-06-01
    Print ISSN: 0009-5893
    Electronic ISSN: 1612-1112
    Topics: Chemistry and Pharmacology
    Published by Springer
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  • 10
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