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  • Polymer and Materials Science  (6)
  • Rice  (3)
  • global convergence  (3)
  • kinetics  (3)
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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
    Mapping QTLs for root traits in a recombinant inbred population from two indica ecotypes in rice (2000)
    Springer
    Theoretical and applied genetics 101 (2000), S. 756-766 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words DNA markers ; Drought resistance ; QTLs ; Rice ; Root penetration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  Evaluation of root traits in rainfed lowland rice is very difficult. Molecular genetic markers could be used as an alternative strategy to phenotypic selection for the improvement of rice root traits. This research was undertaken to map QTLs associated with five root traits using RFLP and AFLP markers. Recombinant inbred lines (RILs) were developed from two indica parents, IR58821–23-B-1–2-1 and IR52561-UBN-1–1-2, that were adapted to rainfed lowland production systems. Using wax-petrolatum layers to simulate a hardpan in the soil, 166 RILs were evaluated for total root number (TRN), penetrated root number (PRN), root penetration index (RPI, the ratio of PRN to TRN), penetrated root thickness (PRT) and penetrated root length (PRL) under greenhouse conditions during the summer and the fall of 1997. A genetic linkage map of 2022 cM length was constructed comprising 303 AFLP and 96 RFLP markers with an average marker space of 5.0 cM. QTL analysis via interval mapping detected 28 QTLs for these five root traits, which were located on chromosomes 1, 2, 3, 4, 6, 7, 10 and 11. Individual QTLs accounted for between 6 and 27% of the phenotypic variation. Most of the favorable alleles were derived from the parent IR58821–23-B-1–2-1, which was phenotypically superior in root traits related to drought resistance. Three out of six QTLs for RPI were detected in both summer and fall experiments and they also were associated with PRN in both experiments. Out of eight QTLs for RPT, five were common in both seasons. Two genomic regions on chromosome 2 were associated with three root traits (PRN, PRT and RPI), whereas three genomic regions on chromosomes 2 and 3 were associated with two root traits (PRT and RPI). Two QTLs affecting RPI and two QTLs affecting PRT were also found in similar genomic regions in other rice populations. The consistent QTLs across genetic backgrounds and the common QTLs detected in both experiments should be good candidates for marker-assisted selection toward the incorporation of root traits in a drought resistance breeding program, especially for rainfed lowland rice.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220051541
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  • 3
    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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  • 4
    Digitale Medien
    Digitale Medien
    Are cell redox or lactate dehydrogenase kinetics responsible for the absence of gluconeogenesis from lactate in sea raven, hepatocytes? (1994)
    Springer
    Fish physiology and biochemistry 13 (1994), S. 59-67 
    Details
    ISSN: 1573-5168
    Schlagwort(e): fish ; sea raven ; gluconeogensis ; hepatocytes ; redox ; LDH ; isozymes ; kinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Previous studies have reported very low rates of gluconeogenesis from lactate in sea raven (Hemitripterus americanus) hepatocytes compared to other teleosts studied. This study examines whether hepatic cell redox or lactate dehydrogenase (LDH) characteristics may explain this observation. Sea raven hepatic optimal LDH activities (pyruvate reductase direction) were more than 40 times less compared with rainbow trout liver values (40 vs 1914 μmol·min−1·g−1 protein). The Km(lactate) was 9.24 and 0.86 mM for sea raven and trout hepatic LDH, but the Km(pyruvate) was similar between the two species (0.11 and 0.21 mM, respectively). These results suggested that sea raven liver LDH did not favour lactate use and was more indicative of the mammalian M-isozyme. Gel electrophoresis showed a predominant intermediate isozyme, with a small amount of the M-type LDH. Phosphoenolpyruvate carboxykinase (PEPCK) was localized to the mitochondrial compartment, while there was no apparent mitochondrial glutamate-oxaloacetate transaminase (GOT) activity. No in vitro lactate flux to glucose was found in untreated, 10 mM ethanol-treated, or 3 mM NH4Cl-treated sea raven hepatocytes, although CO2 production from lactate was decreased by ethanol and increased by NH4Cl. These results provide evidence that cell redox does not limit gluconeogenesis from lactate, while low activities and the kinetic characteristics of LDH may partially explain the low lactate gluconeogenesis reported in sea raven hepatocytes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00004120
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  • 5
    Digitale Medien
    Digitale Medien
    Studies on Non-isothermal Kinetics of the Thermal Decomposition of Eu2(BA)6(bipy)2 (2000)
    Springer
    Journal of thermal analysis and calorimetry 62 (2000), S. 747-755 
    Details
    ISSN: 1572-8943
    Schlagwort(e): benzoic acid ; europium complex ; kinetics ; non-isothermal ; thermal decomposition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The thermal decomposition of Eu2(BA)6(bipy)2 (BA=C2H5N– 2, benzoate; bipy=C10H8N2, 2,2'-bipyridine)and its kinetics were studied under the non-isothermal condition by TG-DTG, IR and SEM methods. The kinetic parameters were obtained from analysis of the TG-DTG curves by the Achar method, the Madhusudanan-Krishnan-Ninan (MKN) method, the Ozawa method and the Kissinger method. The most probable mechanism function was suggested by comparing the kinetic parameters. The kinetic equation for the first stage can be expressed as: dα/dt=Aexp(–E/RT)3(1–α)2/3.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1026785727479
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  • 6
    Digitale Medien
    Digitale Medien
    Globally Convergent Inexact Generalized Newton Method for First-Order Differentiable Optimization Problems (2000)
    Springer
    Journal of optimization theory and applications 106 (2000), S. 551-568 
    Details
    ISSN: 1573-2878
    Schlagwort(e): nonsmooth optimization ; inexact Newton methods ; generalized Newton methods ; global convergence ; superlinear rate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract Motivated by the method of Martinez and Qi (Ref. 1), we propose in this paper a globally convergent inexact generalized Newton method to solve unconstrained optimization problems in which the objective functions have Lipschitz continuous gradient functions, but are not twice differentiable. This method is implementable, globally convergent, and produces monotonically decreasing function values. We prove that the method has locally superlinear convergence or even quadratic convergence rate under some mild conditions, which do not assume the convexity of the functions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1004605428858
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  • 7
    Digitale Medien
    Digitale Medien
    Optical activity based on macromolecular asymmetryPart XXVI of Haloaldehyde Polymers; Part XXV : E.G. Brame, A. M. Raevsky, G. K. Semin, G. D. Jaycox, and O. Vogl, Polymer Bulletin 10(11/12), 521 (1983) (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 13 (1985), S. 1-12 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Optically active isotactic polychloral was prepared in which the optical activity comes exclusively from molecular asymmetry (i.e., helical conformation). Molecular asymmetry requires a high conformational energy barrier for the polymer backbone, and an asymmetric initiator to induce a predominance of one helical screw-sense. Polychloral meets the criteria. Asymmetric initiators used to obtain optically active polychloral include tetramethyl ammonium (+)- or (-)-0-acetylmandelate, tetramethylammonium (+)- or (-)-0-methylmandelate, the lithiumalkoxides of methyl (+)- or (-)-mandelate, lithium cholesten-3β-oxide, lithium cholestan-3β-oxide, and lithium (+)- or (-)-2-octanoxide. Using the above initiators at 0.5 mol %, a maximum specific rotation of [α] D25 = 5000 was obtained for polychloral. Errors in specific rotation were typically ±7%.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1985.020131985102
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  • 8
    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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  • 9
    Digitale Medien
    Digitale Medien
    Projected quasi-Newton algorithm with trust region for constrained optimization (1990)
    Springer
    Journal of optimization theory and applications 67 (1990), S. 369-393 
    Details
    ISSN: 1573-2878
    Schlagwort(e): Two-sided projected Hessians ; trust regions ; differentiable penalty functions ; global convergence ; two-step Q-superlinear rate ; constrained optimization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract In Ref. 1, Nocedal and Overton proposed a two-sided projected Hessian updating technique for equality constrained optimization problems. Although local two-step Q-superlinear rate was proved, its global convergence is not assured. In this paper, we suggest a trust-region-type, two-sided, projected quasi-Newton method, which preserves the local two-step superlinear convergence of the original algorithm and also ensures global convergence. The subproblem that we propose is as simple as the one often used when solving unconstrained optimization problems by trust-region strategies and therefore is easy to implement.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00940481
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  • 10
    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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