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  • 1995-1999  (8)
  • Polymer and Materials Science  (4)
  • Bunch–Parlett factorization  (2)
  • Rice  (2)
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Erscheinungszeitraum
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  • 1
    Digitale Medien
    Digitale Medien
    Regeneration of fertile plants from isolated zygotes of rice (Oryza sativa) (1999)
    Springer
    Plant cell reports 19 (1999), S. 128-132 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Key words Zygote ; Egg cell ; Plant regeneration ; Individual culture ; Rice ; Oryza sativa
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A simple mechanical method has been developed which allows the routine isolation of unfertilized and fertilized egg cells from ovules of Japonica and Indica rice varieties. In the experiments described, the majority of the egg cells and zygotes survived the isolation procedure when the donor plants were in a vigorous state. About 40% of the surviving zygotes underwent sustained development when cultured in Millicell inserts with a non-morphogenic rice feeder-cell culture. Nearly all zygote-derived callus cultures regenerated multiple shoots, which could be subsequently rooted with high efficiency. Zygote-derived plantlets matured to fertile plants when transplanted to soil. So far, about 80 independent plants each from the Japonica variety 'Taipei309' and the Indica variety 'IR58' have been regenerated. The potential of this single-cell regeneration system for marker gene-free transformation is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002990050722
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  • 2
    Digitale Medien
    Digitale Medien
    Expression of the plasma membrane H+-ATPase gene in response to salt stress in a rice salt-tolerant mutant and its original variety (1999)
    Springer
    Theoretical and applied genetics 99 (1999), S. 1006-1011 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Plasma membrane H+-ATPase gene ; Salt stress ; Salt-tolerant mutant ; Rice
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  Plasma membrane (PM) H+-ATPase plays an important role in the establishment and maintenance of ion homeostasis. To investigate its expression in the rice salt-tolerant mutant M-20 and the original variety 77–170 during salt stress, a cDNA fragment corresponding to the PM H+-ATPase gene was obtained by PCR from rice japonica variety 77–170 and designated as OSA3. Sequence analysis of OSA3 revealed its high homology with two other published PM H+-ATPase genes, OSA1 and OSA2, in rice. Southern-blot analysis detected a RFLP between M-20 and 77–170, and one copy of the OSA3 gene was mapped to a position on rice chromosome 12 where a salt tolerance QTL was closely located. The expression of the PM H+-ATPase gene, as revealed by the OSA3 fragment, was compared between M-20 and 77–170. The results demonstrated that M-20 shoots accumulated less transcripts than 77–170 shoots at a later stage of salt treatment, and M-20 showed high expression at 300 mM NaCl while 77–170 reached its maximum at 200 mM NaCl. In roots, the difference in the level of the PM H+-ATPase gene expression between stressed and non-stressed plants was substantially greater in M-20 than that in 77–170. The relative abundance of PM H+-ATPase gene transcripts in M-20 roots may indicate the active role of this gene in the strict control of Na+ and Cl+ uptake into root symplast and apoplast, and further translocation into the shoot, hence leading to the reduced gene expression of M-20 shoots under salt-stress conditions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220051408
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  • 3
    Digitale Medien
    Digitale Medien
    Scaled Optimal Path Trust-Region Algorithm (1999)
    Springer
    Journal of optimization theory and applications 102 (1999), S. 127-146 
    Details
    ISSN: 1573-2878
    Schlagwort(e): Trust-region methods ; unconstrained optimization ; Bunch–Parlett factorization ; optimal paths ; global convergence ; local convergence rates
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract Trust-region algorithms solve a trust-region subproblem at each iteration. Among the methods solving the subproblem, the optimal path algorithm obtains the solution to the subproblem in full-dimensional space by using the eigenvalues and eigenvectors of the system. Although the idea is attractive, the existing optimal path method seems impractical because, in addition to factorization, it requires either the calculation of the full eigensystem of a matrix or repeated factorizations of matrices at each iteration. In this paper, we propose a scaled optimal path trust-region algorithm. The algorithm finds a solution of the subproblem in full-dimensional space by just one Bunch–Parlett factorization for symmetric matrices at each iteration and by using the resulting unit lower triangular factor to scale the variables in the problem. A scaled optimal path can then be formed easily. The algorithm has good convergence properties under commonly used conditions. Computational results for small-scale and large-scale optimization problems are presented which show that the algorithm is robust and effective.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1021846613163
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  • 4
    Digitale Medien
    Digitale Medien
    Modified Partial-Update Newton-Type Algorithms for Unary Optimization (1998)
    Springer
    Journal of optimization theory and applications 97 (1998), S. 385-406 
    Details
    ISSN: 1573-2878
    Schlagwort(e): Unary optimization ; trust-region methods ; indefinite dogleg curve ; Bunch–Parlett factorization ; rank-one update
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract In this paper, we propose two modified partial-update algorithms for solving unconstrained unary optimization problems based on trust-region stabilization via indefinite dogleg curves. The two algorithms partially update an approximation to the Hessian matrix in each iteration by utilizing a number of times the rank-one updating of the Bunch–Parlett factorization. In contrast with the original algorithms in Ref. 1, the two algorithms not only converge globally, but possess also a locally quadratic or superlinear convergence rate. Furthermore, our numerical experiments show that the new algorithms outperform the trust-region method which uses the partial update criteria suggested in Ref. 1.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1022682818387
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  • 5
    Digitale Medien
    Digitale Medien
    In situ studies of epitaxial silicon growth by gas source molecular beam epitaxy (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 7 (1997), S. 215-224 
    Details
    ISSN: 1057-9257
    Schlagwort(e): silicon ; epitaxy ; kinetics ; dynamics ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Physik
    Notizen: The value of in situ monitoring to study growth dynamics and surface reaction kinetics in a gas source molecular beam epitaxy process is illustrated with reference to the growth of Si films on Si(001) substrates using a beam of disilane (Si2H6). By using a combination of reflection high-energy electron diffraction (RHEED) and reflection anisotropy spectroscopy (RAS), we show first how morphological (long-range order) and local electronic structure effects can be separated in the evaluation of growth dynamics. This involves the measurement of step density changes by RHEED concomitantly with the variation in domain coverage on the Si(001) (2×1)+(1×2) reconstructed surface by RAS. This approach is then extended to investigate the kinetics of hydrogen desorption, which is the rate-limiting step in Si growth from Si2H6. It is shown that over a significant temperature range, zeroth-order kinetics are obeyed and this is explained on the basis of a step-mediated desorption process. Finally we show how this influences the growth rate on substrates of differing degrees of vicinality. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Matrix-size interactions in epoxy-glass fibers composites in relation to mechanical relaxations and effects of thermal aging (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 55 (1995), S. 1771-1777 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A study was carried out to examine the effect of removing the size from the surface of glass fibers in order to determine its role with respect to thermoxidative aging. Dynamic mechanical relaxation data have revealed that mechanical losses were always greater than the calculated upper bound values. The effects of removing the size from the surface glass fibers for epoxy matrix composites were found to be completely different when a fluoroligomer was used to modify the resin. Contrary to the case of the conventional epoxy resin, the characteristics of the composites containing fluoroligomer-modified resin were found to be insensitive to the removal of the size from the glass fibers surface. The presence of the size on the surface of the fibers provides an interlayer that degrades through the formation of more lightly crosslinked products than the matrix, thereby providing a large increase in dynamic mechanical losses after thermal aging. © 1995 John Wiley & Sons, Inc.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1995.070551307
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  • 7
    Digitale Medien
    Digitale Medien
    Mechanisms of carbon dioxide laser stereolithography in epoxy-based materials (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 62 (1996), S. 491-500 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: We present in this article the use of infrared laser radiation to achieve localized curing in thermosensitive epoxy resin compounds. In stereolithography, the objective is to cure a localized region in a material by precisely confining the laser energy to the area that is to be cured. Industry already uses ultraviolet laser radiation at 352 nm to fabricate three-dimensional structures. Via infrared laser curing, we demonstrate the viability of a completely thermal localized curing process. In our experiment, we have focused the beam from a carbon dioxide (CO2) laser onto a sample composed of epoxy resin, diethylene triamine, and silica powder. Such resins typically cure, or solidify, when heated to moderately high temperatures, and our results show that we can confine the heating of the material, and, therefore, its curing in all three dimensions. We present a physical and a chemical model to describe the process and measure the curing rate as a function of temperature. In order to model the flow of heat in our sample as a result of infrared laser irradiation, we solved the time-dependent heat equation in cylindrical coordinates using the Crank-Nicholson finite-difference method. The results allow us to predict the curing behavior of the sample as a function of laser irradiation conditions, and we find good agreement with our preliminary experimental observations. © 1996 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Effect of Melting Behaviour on Upward Flame Spread of Thermoplastics (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Fire and Materials 21 (1997), S. 1-6 
    Details
    ISSN: 0308-0501
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Maschinenbau
    Notizen: The effect of melting behaviour on upward flame spread of thermoplastic materials when subjected to small ignition sources and considered to suffer no external flux was studied using large-scale tests. For moderate fire conditions the cone calorimeter was utilized, with the sample set in a vertical orientation to study the melting behaviour of the specimens. Under these conditions the results indicate that the melting behaviour significantly affects upward flame spread behaviour. A pool of the melt which formed at the base of the vertically oriented sample tested creates a pool fire which then controls the fire growth and flame spread. In contrast, it was found that some thermoplastic materials which have higher glass transition temperatures or undergo a special pyrolysis process such as depolymerization, intumescing or charring do not experience significant melting behaviour when exposed to the same thermal insult. As a result, they behave very differently in terms of upward flame spread. The study also indicates that the melting behaviour of thermoplastic materials is an important characteristic in fires which should be taken into account in the development of modelling, in particular for upward flame spread models. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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