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  • Polymer and Materials Science  (6)
  • PACS. 75.30.Et Exchange and superexchange interactions - 75.30.Kz Magnetic phase boundaries (including magnetic transitions, metamagnetism, etc.) - 75.40.Cx Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.)  (2)
  • Pisum  (2)
  • 75.30G  (1)
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Keywords
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Planta 196 (1995), S. 720-726 
    ISSN: 1432-2048
    Keywords: β-Oxidation ; Mitochondrion ; Palmitoylcarnitine ; Pisum ; Solanum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mitochondria from pea (Pisum sativum L.) cotyledons and potato (Solanum tuberosum L.) tubers exhibited a palmitoyl carnitine-dependent, KCN-sensitive stimulation of the oxygen uptake measured in the presence of 0.2mmol·−1 malate (sparker malate), provided a certain concentration range of palmitoylcarnitine was observed. Above this concentration range, which was dependent on the bovine serum albumin (BSA) concentration of the reaction mixture, the mitochondrial oxygen uptake was inhibited by palmitoylcarnitine. Palmitoylcarnitine (racemate) and palmitoyl-l-carnitine were equally effective in stimulating/inhibiting mitochondrial oxygen uptake in the presence of sparker malate. The mitochondrial membrane potential generated in the presence of sparker malate was partially dissipated by palmitoyl-lcarnitine concentrations stimulating the mitochondrial oxygen uptake. The formation of acid-soluble radioactivity in reaction mixtures provided with [1-14C]palmitoyll-carnitine was considerably lower than that expected minimally if the palmitoyl-l-carnitine-stimulated oxygen uptake resulted from palmitoyl-l-carnitine oxidation sparked by malate. Palmitoylcarnitine concentrations resulting in stimulation of the mitochondrial oxygen uptake in the presence of sparker malate also led to a stimulation of succinate-cytochrome c reductase activity, as well as to an increase in the measurable activities of mitochondrial matrix enzymes, indicating loss of both mitochondrial integrity and mitochondrial enzyme latency in the presence of palmitoylcarnitine. Correspondingly, malate-dependent NADH formation was stimulated by palmitoylcarnitine. Neither NAD reduction nor oxygen uptake were observed when the mitochondria were provided with palmitoylcarnitine only. The oxygen uptake due to glycine oxidation by mitochondria from green sunflower (Helianthus annuus L.) cotyledons was affected by palmitoylcarnitine in a similar manner to the oxygen uptake of pea cotyledon and potato tuber mitochondria in the presence of sparker malate. The results lead to the conclusion that the palmitoylcarnitine-dependent stimulation of mitochondrial oxygen uptake observed in the presence of sparker malate results substantially from an enhanced malate oxidation due to the detergent effect of palmitoylcarnitine on the mitochondrial membranes, rather than from palmitoylcarnitine β-oxidation.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Planta 196 (1995), S. 720-726 
    ISSN: 1432-2048
    Keywords: β-Oxidation ; Mitochondrion ; Palmitoylcarnitine ; Pisum ; Solanum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mitochondria from pea (Pisum sativum L.) cotyledons and potato (Solanum tuberosum L.) tubers exhibited a palmitoyl carnitine-dependent, KCN-sensitive stimulation of the oxygen uptake measured in the presence of 0.2mmol·−1 malate (sparker malate), provided a certain concentration range of palmitoylcarnitine was observed. Above this concentration range, which was dependent on the bovine serum albumin (BSA) concentration of the reaction mixture, the mitochondrial oxygen uptake was inhibited by palmitoylcarnitine. Palmitoylcarnitine (racemate) and palmitoyl-l-carnitine were equally effective in stimulating/inhibiting mitochondrial oxygen uptake in the presence of sparker malate. The mitochondrial membrane potential generated in the presence of sparker malate was partially dissipated by palmitoyl-lcarnitine concentrations stimulating the mitochondrial oxygen uptake. The formation of acid-soluble radioactivity in reaction mixtures provided with [1-14C]palmitoyll-carnitine was considerably lower than that expected minimally if the palmitoyl-l-carnitine-stimulated oxygen uptake resulted from palmitoyl-l-carnitine oxidation sparked by malate. Palmitoylcarnitine concentrations resulting in stimulation of the mitochondrial oxygen uptake in the presence of sparker malate also led to a stimulation of succinate-cytochromec reductase activity, as well as to an increase in the measurable activities of mitochondrial matrix enzymes, indicating loss of both mitochondrial integrity and mitochondrial enzyme latency in the presence of palmitoylcarnitine. Correspondingly, malate-dependent NADH formation was stimulated by palmitoylcarnitine. Neither NAD reduction nor oxygen uptake were observed when the mitochondria were provided with palmitoylcarnitine only. The oxygen uptake due to glycine oxidation by mitochondria from green sunflower (Helianthus annuus L.) cotyledons was affected by palmitoylcarnitine in a similar manner to the oxygen uptake of pea cotyledon and potato tuber mitochondria in the presence of sparker malate. The results lead to the conclusion that the palmitoylcarnitine-dependent stimulation of mitochondrial oxygen uptake observed in the presence of sparker malate results substantially from an enhanced malate oxidation due to the detergent effect of palmitoylcarnitine on the mitochondrial membranes, rather than from palmitoylcarnitine β-oxidation.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 98 (1995), S. 1-7 
    ISSN: 1434-6036
    Keywords: 75.30DE ; 75.30G ; 76.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We investigated the field- and temperature dependence of the nuclear magnetic resonance of153Eu in an EuO single crystal sphere at low temperatures in fields up to 7T. The spin-wave analysis yields an ecellent, parameter free description of the magnetization with the exchange constantsJ 1=0.55±1 K,J 2=0.15±1 K and an anisotropy fieldB α=50±1 mT from neutron scattering and ferromagnetic resonance respectively. The influence of a biquadratic exchange within the spin-wave analysis is discussed. The hyperfine field varies with the orientation of the magnetization by 200 kHz. The temperature and field dependence of this anisotropy indicates that it is due to an anisotropic hyperfine coupling tensor. The effect was used to observe the rotation of the domain magnetization in small internal fields and determineB α with greater accuracy than from the spin-wave analysis.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 8 (1999), S. 207-216 
    ISSN: 1434-6036
    Keywords: PACS. 75.30.Et Exchange and superexchange interactions - 75.30.Kz Magnetic phase boundaries (including magnetic transitions, metamagnetism, etc.) - 75.40.Cx Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: For the ferromagnets EuS and GdMg, in which fourth-order exchange interactions (i.e. biquadratic, three-spin and four-spin interactions) have been identified, the deviation of the spontaneous magnetization with respect to the T =0 value is shown to follow a T2 law instead of the famous T3/2 law expected for a Heisenberg ferromagnet. Moreover, the observed T2 law holds for temperatures as large as 0.8TC and the extrapolated magnetization value for does not conform to ferromagnetic saturation. This is because the fourth-order exchange interactions generate a second order-parameter which is assumed to govern the order of the transverse moment components. These moment components have a finite expectation value for at the expense of the Heisenberg order parameter. Like the spontaneous magnetization, the critical field curves B c ( T ) of the metamagnet EuSe and the antiferromagnet EuTe also start decreasing with a T2 term for . It is argued that the T2 law is a consequence of the fourth-order exchange interactions. This is shown experimentally by a study of the critical field curves [0pt] pertinent to the longitudinal (Heisenberg) order-parameter in the diamagnetically diluted antiferromagnets EuxSr1-xTe. In this solid solution series a particular composition of x c =0.85 exists at which the different fourth-order interaction processes compensate each other in the high temperature average. As a consequence, an EuxSr1-xTe sample with x =0.85 meets the requirements of a Heisenberg antiferromagnet at least if a quantity is considered for which the high-temperature average over all fourth-order interactions is decisive. This seems to be the case for the critical field curve [0pt] which gives the phase boundary to the paramagnetic phase. In fact, a crossover from a T2 to a T3/2 law is observed for [0pt] on approaching xc. This, we believe, shows the frequently observed T2 law is caused by the fourth-order interactions.
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  • 5
    ISSN: 1434-6036
    Keywords: PACS. 75.30.Et Exchange and superexchange interactions - 75.30.Kz Magnetic phase boundaries (including magnetic transitions, metamagnetism, etc.) - 75.40.Cx Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: We present a neutron scattering study of the temperature and composition dependence of the MnO-type superstructure reflection intensities in the diamagnetically diluted antiferromagnetic compounds EuxSr1-xTe. In these materials antiferromagnetic biquadratic and ferromagnetic three-spin interactions have been identified recently. These fourth-order non-Heisenberg interactions are able to create their own order parameter which is believed to govern the order of the transverse moment components and which, hence, is directed perpendicular to the common Heisenberg order parameter. The observed MnO-type diffraction intensities originate in the sublattice magnetizations, , of both order parameters. Due to the different composition dependencies for biquadratic interaction processes and three-spin interaction processes , the ferromagnetic three-spin interactions dominate for x 〉 x c =0.85, while for x 〈0.85 the antiferromagnetic biquadratic interactions dominate. Associated with this sign change in the fourth-order interaction sum the transverse order parameter changes from the antiferromagnetic MnO type for x 〈0.85 to ferromagnetic for x 〉0.85. This is noticed as a sudden decrease of the low-temperature MnO scattering intensities at x c =0.85. Although susceptibility measurements reveal clearly a ferromagnetic component for x 〉0.85 no ferromagnetic Bragg intensities were observed in standard neutron scattering spectra using EuTe powder samples. We explain this by the competition of antiferromagnetic biquadratic and ferromagnetic three-spin interactions whereby a disturbed ferromagnetic superstructure may be generated which gives rise also to weak MnO-type diffraction lines. It is found that the resulting obeys a T2 law until a temperature as large as 0.75TN irrespective of the nature of the transverse order parameter. The T2 law must, hence, be common to both types of order parameter showing that the fourth-order interactions re-define the spin dynamics of both completely. From the linear composition dependence of the normalized T2 coefficient the existence of three-spin interactions is again confirmed.
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  • 6
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 7
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Viscoses prepared from untreated pulp and from pulp pretreated by high-energy radiation were rheologically examined. The results are discussed with regard to the state of solution of the viscoses. It turned out to be possible, when preparing the viscose from pretreated pulp, to reduced the addition of CS2 to a level below 30% (in relation to cellulose) without deteriorating the state of solution of the viscose.
    Notes: Viskosen aus unbehandeltem und strahlenvorbehandeltem Zellstoff wurden rheologisch untersucht. Die Meßergebnisse werden hinsichtlich des Lösungszustandes der Viskose diskutiert. Es zeight sich, daß bei den Viskosen aus strahlenvorbehandeltem Zellstoff eine Verminderung des CS2-Einsatzes bei der Viskoseherstellung bis auf Werte unter 30% CS2 (Bezogen auf Cellulose) möglich ist, ohne den Lösungszustand der Viskose zu verschlechtern.
    Additional Material: 7 Ill.
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  • 8
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The principles of fibre formation in the wet spinning process are investigated by means of rheological measurements. The 1st normal stress difference of technologically important shear rates is determined from the die swell of a freely emerging viscose jet. Moreover, the Barus swell of a viscose jet extruded into spinning bath as well as the rheological strength as a function of the spin-draw ratio of the filament were determined. The load-elongation diagram resulting from the deformation of the jet is shown to be essential for the stability of the spinning process.
    Notes: Grundlagen der Fadenbildung beim Naßspinnprozeß werden an Hand rheologischer Messungen untersucht. Dazu wird die 1. Normalspannungsdifferenz für betrieblich relevante Schergeschwindigkeiten aus der Strahlaufweitung eines frei austretenden Viskosestrahls ermittelt. Des weiteren werden die Barusaufweitung eines in ein Spinnbad extrudierten Viskosestrahls sowie die rheologische Kraft in Abhängigkeit von Verzug des Fadens bestimmt und das aus der Strahlverformung resultierende Beanspruchungs-Dehnungs-Diagramm als wesentlich für die Spinnstabilität begründet.
    Additional Material: 9 Ill.
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  • 9
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The notion of the reactivity of dissolving pulps, which is used to explain differences in the chemical behaviour during subsequent processing to viscose, was characterized by the molecular weight distribution of cellulose, 13C-NMR investigations of the pulp, determination of the clogging value of the viscose when using reduced CS2 quantities, and distribution of the xanthate groups. Three possibilities for enhancing the reactivity of dissolving pulps are demonstrated: Pretreatment of pulp with electron-rays prior to processing of viscose, enhanced delignification of the pulp during discontinuous cooking, and energy-intensified hi-heat washing during continuous cooking permit the production of pulps having higher reactivity.
    Notes: Die Reaktivität von Chemiefaserzellstoffen, die zur Erklärung der Unterschiede im chemischen Verhalten bei der Verarbeitung zu Viskose herangezogen wird, wurde durch die Molmassenverteilung der Cellulose, durch 13C-NMR-Untersuchungen des Zellstoffs, Bestimmung des Filterwertes der Viskose bei reduziertem CS2-Einsatz und durch die Verteilung der Xanthatgruppen charakterisiert. Drei Möglichkeiten zur Erhöhung der Reaktivität des Zellstoffs werden aufgezeigt: Die Behandlung des Zellstoffs mit Elektronenstrahlen vor der Verarbeitung zu Viskose, die stärkere Delignifizierung des Zellstoffs bei der diskontinuierlichen Kochung und die energieintensivierte Hi-Heat-Wäsche.
    Additional Material: 6 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Fire and Materials 3 (1979), S. 167-170 
    ISSN: 0308-0501
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The development of plastics with improved flame retardant properties is going through a phase of stagnation. Fire test concepts are following a new direction and the serial tests currently used do not adequately tie up with the development objective of reducing fire risks. In the short term no improvement in this situation is expected.
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