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  • 1
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Pure and Ag-doped Bi2212 bulks were prepared by melt processing in 9T magnetic field. It is found that an obvious texture has been developed in the Ag-doped bulks; while in the pure Bi2212 bulks no texture can be observed. Further analysis shows that the texture development in Bi2212 bulks is highly sensitive to the maximum temperature in the melt processing. Ag-doping leads to a homogeneous melting at a lower temperature and the texture can thus be obtained in the Ag-doped bulks.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Acta mechanica 13 (1972), S. 191-203 
    ISSN: 1619-6937
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Ergebnisse vonOnat undShield, sowie vonGreen, über die Traglast von symmetrisch sich verjüngenden, einseitig eingespannten Balken, die durch eine an ihrem Ende angreifende uniform verteilte Querkraft belastet sind, werden erweitert um den gesamten Bereich der geometrischen Parameter zu erfassen. Mit Ausnahme sehr kurzer Balken werden eng zusammenliegende Schranken erhalten. Zusätzlich wird der Einfluß einer parabolischen Verteilung der Querkraft untersucht und als klein befunden. Für den Fall sehr langer Balken wird eine vollständige Lösung gegeben. Abschließend wird ein optimales Entwurfsproblem betrachtet: Für eine vorgegebene Balkenlänge und Belastung finde man den Verjüngungswinkel, der das Gewicht zu einem Minimum macht. Dieses Minimum wird immer für einen Verjüngungswinkel (zwischen Ober-und Unterseite) zwischen O und 15° angenommen.
    Notes: Summary Results ofOnat andShield and ofGreen on the collapse loads of symmetrically tapered cantilever beams under a uniformly distributed end shear are extended to cover the entire range of geometric parameters. Close bounds are obtained except for very short beams. In addition, the effect of a parabolic distribution of end shear upon the lower bound is investigated and found to be small. For large beams complete solutions are exhibited. Finally, an optimum design problem is considered: for fixed beam length and end load find the angle of taper which minimizes the weight. The minimum is always achieved for a taper angle (top and bottom) between zero and fifteen degrees.
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  • 3
    ISSN: 1432-2242
    Keywords: Key words  Triticum aestivum ; Genetic transformation ; Thaumatin-like protein ; Wheat scab ; Fluorescent in situ hybridization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract   The possibility of controlling wheat scab (caused by Fusarium graminearum Schw.) was explored by engineering wheat plants for constitutive expression of pathogenesis-related (PR) protein genes. A rice thaumatin-like protein (TLP) gene (tlp) and a rice chitinase gene (chi11) were introduced into the spring wheat cultivar ’Bobwhite’ by co-transformation of the plasmids pGL2ubi-tlp (ubiquitin/tlp//CaMV 35S/hpt) and pAHG11 (CaMV 35S/chi11//ubiquitin/bar). The transformation was by biolistic bombardment. Bialaphos was used as the selection reagent. The integration and expression of the tlp, bar, chi11 and hpt genes were analyzed by Southern, Northern and Western blot analyses. The four transgenes co-segregated in the T1 progeny of the transgenic plant and were localized at the telomeric region of the chromosome 6A long arm by sequential N-banding and fluorescent in situ hybridization (FISH) using pAHG11 or pGL2ubi-tlp as the probes. Only the transgenes tlp and bar, under the control of the ubiquitin promoter-intron, were expressed. No expression of the chi11 and hpt genes, controlled by the CaMV 35S promoter, was detected in T1 plants. After inoculation with conidia of F. graminearum, the symptoms of scab developed significantly slower in transgenic plants of the T1, T2 and T3 generations expressing the tlp gene than in non-transformed control plants. This is the first report of enhanced resistance to F. graminearum in transgenic wheat plants with constitutive expression of TLP.
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  • 4
    ISSN: 1432-2242
    Keywords: Key wordsTriticum aestivum ; Transformation ; Microprojectile bombardment ; Chitinase gene ; bar gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Our long-term goal is to control wheat diseases through the enhancement of host plant resistance. The constitutive expression of plant defense genes to control fungal diseases can be engineered by genetic transformation. Our experimental strategy was to biolistically transform wheat with a vector DNA containing a rice chitinase gene under the control of the CaMV 35 S promoter and the bar gene under control of the ubiquitin promoter as a selectable marker. Immature embryos of wheat cv ‘Bobwhite’ were bombarded with plasmid pAHG11 containing the rice chitinase gene chi11 and the bar gene. The embryos were subcultured on MS2 medium containing the herbicide bialaphos. Calli were then transferred to a regeneration medium, also containing bialaphos. Seventeen herbicide-resistant putative transformants (T0) were selected after spraying with 0.2% Liberty, of which 16 showed bar gene expression as determined by the phosphinothricin acetyltransferase (PAT) assay. Of the 17 plants, 12 showed the expected 35-kDa rice chitinase as revealed by Western blot analysis. The majority of transgenic plants were morphologically normal and self-fertile. The integration, inheritance and expression of the chi11 and bar genes were confirmed by Southern hybridization, PAT and Western blot analysis of T0 and T1 transgenic plants. Mendelian segregation of herbicide resistance was observed in some T1 progenies. Interestingly, a majority of the T1 progeny had very little or no chitinase expression even though the chitinase transgene was intact. Because PAT gene expression under control of the ubiquitin promoter was unaffected, we conclude that the CaMV 35 S promoter is selectively inactivated in T1 transgenic wheat plants.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 20 (1978), S. 567-575 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of two grinding methods, hammer milling and defibrizing by disk refining, on the fermentability of ryegrass straw were investigated. Disk refined or defibrized straw produced more sugar than hammer milled straw. Release of sugar was especially pronounced when H2SO4 was added to the straw during the defibrizing process. In vitro rumen digestibility was significantly higher (P 〈 0.1) for defibrized than for hammer milled straw. With semisolid culture the level of yeast growth was about three times as high on the defibrized as on hammer milled straw. A scanning electron micrograph revealed that defibrizing removed the waxy surface of the straw as well as separating fiber bundles, so that the surface area of the exposed fiber structure was increased.
    Additional Material: 3 Ill.
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  • 6
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The hemicellulose fraction of ryegrass straw was extracted with NaOH and used for the production of glucose isomerase by Streptomyces flavogriseus. The level of hemicellulose extracted increased proportionately with increasing NaOH concentration up to about 4%, then the rate of increase slowed down. Hemicellulose extraction was facilitated by the combined application of heat and NaOH. Approximately 15% hemicellulose (12% as pentosan) could be obtained by treating straw with 4% NaOH for either 3 hr at 90°C or 24 hr at room temperature. The highest level (3.04 units/ml culture) of intracellular glucose isomerase was obtained when the organism was grown at 30°C for two days on 2% straw hemicellulose. The organism also produced a high yield of glucose isomerase on xylose or xylan. The NaOH-treated straw residue, after removal of hemicellulose, had approximately 75% higher digestibility and 20% higher feed efficiency for weanling meadow voles than untreated straw. Thus, the residue could be used as animal feed. A process for the production of glucose isomerase and animal feed from ryegrass straw was also proposed.
    Additional Material: 4 Ill.
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  • 7
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Chilling (4 °C) induced a prolonged high level of intracellular Ca2+ (Ca2+ overload) and lipid peroxidation in maize (Zea mays L. cv Black Mexican Sweet) cultured cells. However, such Ca2+ overload and enhanced lipid peroxidation were not seen in abscisic acid (ABA)-treated cells, which had an improved chilling tolerance. A Ca2+ ionophore, A23187, caused Ca2+ overload in both ABA-treated maize cells and the untreated control, whereas an enhanced lipid peroxidation was detected only in the control. The high level of active oxygen species (AOS) in the control during chilling at 4 °C could be reduced by the presence of lanthanum (La3+), a Ca2+ channel blocker, in the medium. Moreover, both the A23187-induced lipid peroxidation and AOS production in the control could be reduced by extracellular EGTA, a Ca2+ chelator. Laser-scanning confocal microscopy revealed that mitochondria were one of the major AOS sources under chilling and during A23187 treatment. In vitro assays showed that superoxide production in isolated maize mitochondria was enhanced by the presence of Ca2+. Findings suggest that chilling-induced Ca2+ influx in the control triggers a marked generation of AOS, which in turn results in the enhanced lipid peroxidation. The ability of ABA-treated cells to avoid the chilling-induced Ca2+ influx may serve as a mechanism that prevents the chilling-induced oxidative stress and thus results in less chilling injury.
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  • 8
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Previous studies of maize suspension-cultured cells showed that abscisic acid (ABA) treatment at warm temperatures improved the tolerance of cells to subsequent chilling. In the present study, it is shown that both ABA-treated and untreated maize cells accumulated proline in response to chilling. However, ABA-treated cells displayed less lipid peroxidation during chilling, and thus, unlike untreated cells, were able to retain the accumulated proline intracellularly. Proline application experiments indicate that an intracellular proline level higher than 2 µmole (g FW)−1 prior to chilling was needed to meaningfully reduce chilling-enhanced lipid peroxidation and significantly improve chilling tolerance. The results suggest that total proline accumulation in ABA-treated as well as untreated cells during chilling was enough to potentially improve chilling tolerance, but proline leakage rendered the control cells unable to benefit from the endogenous synthesis of proline in relation to the alleviation of chilling injury. Proline participated in chilling tolerance improvement in ABA-treated maize cells, as evidenced by: (1) the inhibition of proline accumulation by l-methionine-d, l-sulphoximine (MSO), an inhibitor of glutamine synthetase, reduced ABA-improved chilling tolerance, and (2) the addition of glutamine into the medium prevented the MSO-induced reduction in chilling tolerance. The revised relationship between proline accumulation and membrane stability at cold is discussed in the light of these current findings.
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  • 9
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Chilling tolerance was increased in suspension-cultured cells and seedlings of maize (Zea mays L. cv ‘Black Mexican Sweet’) grown in media containing glycinebetaine (GB). A triphenyl tetrazolium chloride (TTC) reduction test indicated that after a 7 d chilling period at 4 °C, cells treated with 1 mm GB at 26 °C for 1 d had a survival rate (30%) that was twice as high as that of untreated controls. The addition of 2·5 m M GB to the culture medium resulted in maximum chilling tolerance (40%). The results of a cell regrowth assay were consistent with viability determined by the TTC method. In suspension-cultured cells supplemented with various concentrations of GB, accumulation of GB in the cells was proportional to the GB concentration in the medium and was saturated at a concentration of 240 μmol (g DW)−1. The degree of increased chilling tolerance was positively correlated with the level of GB accumulated in the cells. The increased chilling tolerance was time-dependent; i.e. it was first observed 3 h after treatment and reached a plateau after 14 h. Feeding seedlings with 2·5 m M GB through the roots also improved their chilling tolerance, as evidenced by the prevention of chlorosis after chilling for 3 d at 4 °C/2 °C. Lipid peroxidation, as expressed by the production of malondialdehyde, was significantly reduced in GB-treated cells compared with the untreated controls during chilling. These results suggest that increased chilling tolerance may be due, in part, to the reduction of lipid peroxidation of the cell membranes in the presence of GB.
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  • 10
    Publication Date: 2017-10-04
    Description: AZ31 base alloy were subjected to friction stir processing (FSP) with different rotating speed. The effect of FSP on the microstructure, mechanical properties and damping capacities of AZ31 alloy was discussed in this paper. The fine and equiaxed grains were obtained in the SZ for FSPed samples with the rotating speed from 1300rpm to 1700rpm with the average grain size of 11.82μm, 12.93μm and 14.50μm, respectively. The FSPed samples had higher ductility and damping capacities compared with the AZ31 base alloy. The ductility and damping values Q 0 -1 (ε=10 -4 ) and Q H -1 (ε=10 -3 ) of 1500rpm FSPed sample were increased by 121.44%, 5.02% and 7.49%, respectively.
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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