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  • precursor chemistry  (3)
  • Engineering  (2)
  • Restriction fragment length polymorphism (RFLP)  (2)
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  • 1
    Digitale Medien
    Digitale Medien
    Molecularmarker diversity and hybrid sterility in indica-japonica rice crosses (1997)
    Springer
    Theoretical and applied genetics 95 (1997), S. 112-118 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Diallel cross ; Hybrid rice ; Oryza sativa ; Restriction fragment length polymorphism (RFLP) ; Simple sequence repeat (SSR)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  The partial sterility of hybrids between the indica and japonica rice subspecies of Asian cultivated rice is a serious constraint for utilizing inter-subspecific heterosis in hybrid rice breeding. In this study, we have investigated the relationship between molecular-marker polymorphism and indica-japonica hybrid fertility using a diallel set involving 20 rice accessions including 9 indica and 11 japonica varieties. Spikelet fertility of the resulting 190 F1s and their parents was examined in a replicated field trial. Intra-subspecific hybrids showed much higher spikelet fertility than inter-subspecific hybrids except in crosses involving wide-compatibility varieties. The parents were surveyed for DNA polymorphism using 96 RFLP and ten SSR markers, which revealed extensive genetic differentiation between indica and japonica varieties. A large number of markers detected highly significant effects on hybrid fertility. The chromosomal locations for many of the positive markers coincided well with previously identified loci for hybrid sterility. The correlation between hybrid fertility and parental distance was low in both intra- and inter-subspecific crosses. The results suggest that the genetic basis of indica-japonica hybrid sterility is complex. It is the qualitative, rather than the quantitative, difference between the parents that determines the fertility of hybrids.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220050538
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  • 2
    Digitale Medien
    Digitale Medien
    Determination of Particle Size and Shape during the Hydrolysis of Pb(Zr0.3Ti0.7)O3 Precursor Solutions (1998)
    Springer
    Journal of sol gel science and technology 11 (1998), S. 141-152 
    Details
    ISSN: 1573-4846
    Schlagwort(e): precursor chemistry ; lead zirconate titanate ; hydrolysis ; PCS ; SAXS
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The formation and growth of polymeric particles during the hydrolysis and condensation of PbZr0.3Ti0.7 O3 (PZT 30/70) sol-gel precursor solutions have been investigated by using photon correlation spectroscopy (PCS), small angle X-ray scattering (SAXS) and by measuring their rheological properties. The measurements showed that the growth of the particles in the transition of PZT sol to gel followed a simple polymerisation process. Solution A (containing ‘by-products’) and Solution B (‘by-products’ removed) displayed a similar plot of logarithmic viscosity against logarithmic time, indicating that the particles in both solutions have similar structures after hydrolysis. The changes in viscosity and particle size with time were described by single logarithmic growth models. However, the increasing rate of logarithmic particle size in Solution B is higher than that in Solution A. A model for the form of the aggregates is discussed which is applicable to PZT organometal-particle aggregation process in systems with acetic acid as a modifier.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008641429895
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  • 3
    Digitale Medien
    Digitale Medien
    A Comparison of the Nanostructure of Lead Zirconate, Lead Titanate and Lead Zirconate Titanate Sols (1999)
    Springer
    Journal of sol gel science and technology 15 (1999), S. 13-22 
    Details
    ISSN: 1573-4846
    Schlagwort(e): precursor chemistry ; lead zirconate titanate ; hydrolysis ; PCS ; SAXS
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Sol-gel processing has been widely used for the fabrication of lead zirconate titanate (PZT) thin films. To successfully and consistently make high quality thin films for different applications, we must develop a fundamental understanding of the structures of the sols. In this study, the characters of lead titanate (PT) and lead zirconate (PZ)sols were studied by measuring the rheological properties and particle sizes in them and comparing their behaviours. The average particle sizes in unhydrolysed PT, PZ and PZT sols are 11.5, 1.0, and 6.0 nm, respectively. PT sol has the highest rate of hydrolysis. It gels at about 24 h after hydrolysis. PZ and PZT sols have a quite similar feature in hydrolysis. The reasons for the differences in the hydrolysis behaviour of the different types of sol are discussed in terms of a model which indicates that the inhomogeneous sols consist of 5 to 6 nm PT particles surrounded by much smaller PZ particles, which tend to dominate the sol behaviour.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008759520087
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  • 4
    Digitale Medien
    Digitale Medien
    Molecular marker analyses of powdery mildew resistance in barley (1994)
    Springer
    Theoretical and applied genetics 88 (1994), S. 733-740 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Restriction fragment length polymorphism (RFLP) ; Hordeum vulgare ; Quantitative resistance ; Erysiphe graminis f. sp.hordei ; Diallel
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Powdery mildew, caused byEryisphe graminis f. sp.hordei, is one of the most important diseases of barley (Hordeum vulgare). A number of loci conditioning resistance to this disease have been reported previously. The objective of this study was to use molecular markers to identify chromosomal regions containing genes for powdery mildew resistance and to estimate the resistance effect of each locus. A set of 28 F1 hybrids and eight parental lines from a barley diallel study was inoculated with each of five isolates ofE. graminis. The parents were surveyed for restriction fragment length polymorphisms (RFLPs) at 84 marker loci that cover about 1100 cM of the barley genome. The RFLP genotypes of the F1s were deduced from those of the parents. A total of 27 loci, distributed on six of the seven barley chromosomes, detected significant resistance effects to at least one of the five isolates. Almost all the chromosomal regions previously reported to carry genes for powdery mildew resistance were detected, plus the possible existence of 1 additional locus on chromosome 7. The analysis indicated that additive genetic effects are the most important component in conditioning powdery mildew resistance. However, there is also a considerable amount of dominance effects at most loci, and even overdominance is likely to be present at a number of loci. These results suggest that quantitative differences are likely to exist among alleles even at loci which are considered to carry major genes for resistance, and minor effects may be prevalent in cultivars that are not known to carry major genes for resistance.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01253978
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  • 5
    Digitale Medien
    Digitale Medien
    Heterometallic lead-titanium oxyalkoxide precursors to lead titanate thin films (1994)
    Springer
    Journal of sol gel science and technology 2 (1994), S. 29-34 
    Details
    ISSN: 1573-4846
    Schlagwort(e): precursor chemistry ; lead titanate ; thin films ; hydrolysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Two lead titanium oxyalkoxides with composition Pb2Ti4O2(O2CCH3)2(OC2H5)14 and Pb2Ti2O2(O2CCH3)2(OCH(CH3)2)8 have been isolated and characterised by elemental analysis, IR, 207Pb NMR and molecular weight measurements. X-ray structural analysis of the 1:2 complex confirmed the presence of two Pb2Ti2O units which are linked by a common Pb···Pb edge and are held together by alkoxide and acetate bridges. The acetate groups have migrated from the Pb to the Ti centres during the reaction. Hydrolysis of the 1:1 Pb/Ti complex produced clear gels providing the H2O/complex ratio was less than 4. Heat treatment of the gel results in loss of residual organics below 400°C. The XRD pattern indicates the presence of the pyrochlore and perovskite phases after heating at 500°C but the sample is poorly crystalline. Complete conversion to the perovskite phase of lead titanate occurs on heating to 600°C for 1 hour. Thin films of lead titanate were deposited by dip-coating a solution of this complex in isopropanol. Analyses of the films, carried out using electron microprobe, Scanning Auger Spectroscopy and Rutherford Backscattering, indicated that they were of excellent quality, crystalline after heating at 600°C and with relatively sharp substrate-coating interface.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00486209
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  • 6
    Digitale Medien
    Digitale Medien
    Design sensitivity coefficients for elasto-viscoplastic problems by boundary element methods (1992)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 34 (1992), S. 947-966 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: This paper is concerned with accurate and efficient determination of design sensitivity coefficients (DSCs) for solid mechanics problems with small strains and rotations, but with material non-linearities present (elasto-plastic or elasto-viscoplastic problems). This approach is based on direct differentiation (DDA) of the relevant derivative boundary element method (DBEM) formulation of the problem. Analytical differentiation of the DBEM equations leads to singular integral equations for the DSCs with weakly (logarithmically for 2-D) singular kernels which are easy to deal with. Also, stress components and their sensitivities are obtained on the boundary of a body with great accuracy. These quantities are typically difficult to obtain accurately from finite element methods (FEM).A computer program for general two-dimensional (plane strain and plane stress) problems has been developed based on the above formulation. Numerical results are presented for some sample problems and these are compared against direct solutions. The agreement between the DBEM and direct solutions is excellent for these examples.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620340318
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  • 7
    Digitale Medien
    Digitale Medien
    A numerical study of the effect of free surface and water depth on the stability of wakes: use of GDQ formulation (1997)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 24 (1997), S. 1079-1090 
    Details
    ISSN: 0271-2091
    Schlagwort(e): wake flow ; free surface ; instability ; GDQ method ; Engineering ; Numerical Methods and Modeling
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Maschinenbau
    Notizen: The instability character of a wake in the presence of a free surface is examined by a recently developed GDQ (generalized differential quadrature) numerical method. It is shown that at low Froude number the wake near a free surface is convectively unstable, but when the Froude number is increased further it becomes absolutely unstable. The effect of water depth on the stability property of the wake flow is also investigated. It is found that the influence of water depth on the critical point of instability is limited to at most 20% variation in the complex frequency, while the change in temporal growth rate is also limited to about 20%. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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