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  • 25.70.Np  (5)
  • Inorganic Chemistry  (2)
  • Phytochrome (as inductor)  (2)
  • 1
    ISSN: 1434-601X
    Keywords: 25.70.Np ; 23.20.En ; 21.60.-n
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In the fragmentation of 500 MeV/u46Ti the spin alignment of43mSc (I=19/2−, T1/2=473 ns) fragments was observed by the Time Dependent Perturbed Angular Distribution (TDPAD) method. The measurement was performed for different cuts in the longitudinal momentum distribution. A positive spin alignment of about 35% was observed in the center and a negative alignment of about 15% in the wing of the distribution. For the different cuts the relative production of the 19/2− state was measured. In the wing of the distribution the isomeric ratio N(19/2−)/total43Sc is about 15 times larger than in the center. The results of this pilot experiment are discussed in the frame of a shell-model.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-601X
    Keywords: 21.10.Ft ; 25.70.Np ; 27.40.+Z
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract At the projectile-fragment separator FRS of GSI, relativistic secondary beams of about 520 MeV/nucleon were produced by fragmentation of a primary beam of58Ni at 650 MeV/nucleon in a beryllium target. By means of aΔE—Bρ—TOF measurement, the fragments have been identified and their charge-changing probabilities in targets of CH2, C, Al, and Pb have been determined. We describe the results for the total charge-changing cross sections in this first paper, whereas a second article deals with the partial charge-changing cross sections. At the drip line, the measured charge-changing cross sections exhaust close to 100% of the total interaction cross sections as calculated with semiempirical models. The measurements at the proton drip line with low-Z targets indicate that only a very small increase of the cross sections may be observed, whereas the measurements with a lead target show that no significant increase of the total charge-changing cross sections is present which would be a hint for low-lying dipole strength. Our experimental data are compared to Glauber-type calculations.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2048
    Keywords: Glutamine synthetase ; Nitrate (as inductor) ; Nitrite reductase ; Phytochrome (as inductor) ; Sinapis (nitrate assimilation)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The extent to which the appearances of nitrite reductase (NIR; EC 1.7.7.1) and glutamine synthetase (GS; EC 6.3.1.2) are coordinated was studied in mustard (Sinapis alba L.) seedlings. It was established by immunotitration that the increased activities of NIR and GS in the presence of light and nitrate can be attributed to the de-novo synthesis of enzyme protein. The bulk of the NIR and GS was found in the developing cotyledons. In the absence of nitrate in the growth medium there was no coordinate appearance of NIR and GS. While light strongly stimulated the appearance of GS, the level of NIR was hardly affected and remained low. On the other hand, in the presence of nitrate in the medium the appearances of NIR and GS were strictly coordinated, the GS level being considerably above that of NIR. It is argued that phytochrome-controlled synthesis of GS in the absence of nitrate is part of the mechanism to reassimilate ammonium liberated during proteolysis of storage protein and metabolism of the resulting amino acids, whereas the strictly coordinated synthesis in the presence of light and nitrate indicates the dominance of nitrate assimilation under these circumstances. The fact that the level of GS was always considerably above that of NIR appears to be a safety measure to prevent ammonium accumulation.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2048
    Keywords: Glutamine synthetase ; Nitrate (as inductor) ; Nitrite reductase ; Phytochrome (as inductor) ; Sinapis (nitrate assimilation)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The extent to which the appearances of nitrite reductase (NIR; EC 1.7.7.1) and glutamine synthetase (GS; EC 6.3.1.2) are coordinated was studied in mustard (Sinapis alba L.) seedlings. It was established by immunotitration that the increased activities of NIR and GS in the presence of light and nitrate can be attributed to the de-novo synthesis of enzyme protein. The bulk of the NIR and GS was found in the developing cotyledons. In the absence of nitrate in the growth medium there was no coordinate appearance of NIR and GS. While light strongly stimulated the appearance of GS, the level of NIR was hardly affected and remained low. On the other hand, in the presence of nitrate in the medium the appearances of NIR and GS were strictly coordinated, the GS level being considerably above that of NIR. It is argued that phytochrome-controlled synthesis of GS in the absence of nitrate is part of the mechanism to reassimilate ammonium liberated during proteolysis of storage protein and metabolism of the resulting amino acids, whereas the strictly coordinated synthesis in the presence of light and nitrate indicates the dominance of nitrate assimilation under these circumstances. The fact that the level of GS was always considerably above that of NIR appears to be a safety measure to prevent ammonium accumulation.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1434-601X
    Keywords: 25.70.Np
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The longitudinal-momentum distributions of projectile fragments from 0.8 A GeV136Xe and 1 A GeV197Au projectiles impinging on targets of beryllium and aluminium, respectively, have been measured using the projectile-fragment separator FRS at GSI. Different momentum distributions have been found for two different classes of fragmentation processes: the abundant hot fragmentation with several nucleons evaporated from the prefragments, and the rare cold fragmentation with only protons removed from the projectile, but no nucleons evaporated. The data are compared to model calculations.
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  • 6
    ISSN: 1434-601X
    Keywords: 25.70.Np ; 27.50. + e
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have measured production cross-sections of the new neutron-rich isotopes58Ti,61V,63Cr,66Mn,69Fe,71Co and neighbouring isotopes that have been identified as projectile fragments from reactions between a 500 MeV/u86Kr beam and a beryllium target. The isotope identification was performed with the zero-degree magnetic spectrometer FRS at GSI, using in addition time-of-flight and energy-loss measurements. The experimental production cross-sections for the new nuclides and neighbouring isotopes are compared with an empirical parametrization. The resulting prospects for reaching even more neutron-rich isotopes, such as the doubly-magic nuclide78Ni, are discussed.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1434-601X
    Keywords: 21.10.Ft ; 25.70.Np ; 27.40.+z
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract At the projectile-fragment separator FRS of GSI, relativistic secondary beams of about 520 MeV/nucleon were produced by fragmentation of a primary beam of58Ni at 650 MeV/nucleon in a beryllium target. By means of aΔE—Bρ—TOF measurement, the fragments were identified and their charge-changing probabilities in targets of (CH2) n , C, Al, and Pb placed at the exit of the FRS were determined. Whereas a first article dealt with the total charge-changing cross sections, we describe in this second article the element distributions of these secondary fragments, which are found to depend strongly on the isospin of the secondary projectile as well as on the target material. In the case of the lead target, the influence of the electromagnetic dissociation is clearly visible in the one-proton and two-proton removal channels. The preference for the formation of even-Z fragments is much more pronounced for exotic secondary projectiles than for projectiles close to stability. Calculations with a geometrical abrasion-ablation model allow to understand the global features of the experimental data. However, far from stability, the discrepancies between calculations and experimental data increase.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on Oxide Catalysts. XLIV. Modification of the Catalytic Behavior of Modified ZSM-5 Zeolites by Thermal TreatmentThe catalytic activity, the shape selectivity, and the deactivation behavior of ZSM-5 in paraffin cracking reactions can be regulated by a thermal pretreatment. A minimum of the deactivation rate as a function of zeolite pretreatment time at 600°C found in the hexane cracking could be verified in the methanol conversion reaction to gasoline.
    Notes: Die katalytische Aktivität, die Formselektivität und das Aktivität-Zeit-Verhalten des ZSM-5 beim Spalten von Paraffinen kann durch thermische Vorbehandlung stark beeinflußt werden. Ein in der Spaltung von Hexan gefundenes Minimum der Desaktivierungsgeschwindigkeit als Funktion der Dauer der Vorbehandlung bei 600°C konnte in der Methanolumwandlung zu Benzin verifiziert werden.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on Oxide Catalysts. XXXVII. On the Influence of Preparation Conditions on the Properties of Silica-AluminaSilica-alumina samples of different composition were prepared by coprecipitation from aqueous solutions at pH = 6 and pH = 9, respectively. Structures and properties of the solids were characterized (i.r., DTA, X-ray, molybdato method, surface acidity, catalytic activity in the cracking reaction of cumene). Solid composition and pH value of the precipitation medium equally exhibit influence on the structure of the silica-alumina (kind of incorporation of the aluminium) and thereby on the acidic and catalytic properties of the solids. Silica-alumina of equal composition but precipitated at different pH values may widely differ in their properties including activity-composition dependency.
    Notes: Durch Mischfällung wurden aus wäßrigem Medium bei pH = 6 bzw. pH = 9 röntgenamorphe Al2O3—SiO2-Festkörper unterschiedlicher Zusammensetzung hergestellt. Aufbau und Eigenschaften der Festkörper wurden charakterisiert (IR, DTA, Röntgendiffraktometrie, Molybdatmethode, Oberflächenacidität, katalytische Aktivität in der Spaltung von Cumen). Zusammensetzung und pH-Wert des Fällmediums beeinflussen gleichermaßen den Aufbau des Al2O3—SiO2 (Art des Einbaus des Aluminiums) und damit dessen acide und katalytische Eigenschaften. Al2O3—SiO2-Proben gleicher Zusammensetzung können unterschiedliche Eigenschaften aufweisen, wenn sie bei unterschiedlichen pH-Werten gefällt wurden. Das trifft auch auf die Form der Abhängigkeit der katalytischen Aktivität von der Zusammensetzung zu.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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