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  • 1
    Electronic Resource
    Electronic Resource
    Photorefractive parameters and light-induced absorption in BaTiO3 (1995)
    Springer
    Applied physics 61 (1995), S. 553-557 
    Details
    ISSN: 1432-0630
    Keywords: PACS: 78.20; 61.72; 72.40.+w
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract.  The light-induced absorption coefficient Δα and the light-intensity dependence of the photorefractive parameters known as the effective trap density NE, the mobility-recombination product μτr and the photo- conductivity σph have been measured for four nominally pure BaTiO3 crystals. The qualitative correlation between Δα, NE, (μτr) -1 and σph has been revealed. The results are explained by the two-center model of deep and shallow traps.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01540258
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  • 2
    Electronic Resource
    Electronic Resource
    High-resolution refinement of the hexagonal A-DNA octamer d(GTGTACAC) at 1.4 Å (1993)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 49 (1993), S. 282-291 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The hexagonal crystal form of the octamer d(GTGTACAC), grown in the presence of spermine, has unit-cell dimensions a = b = 32.18 and c = 78.51 Å, space group P6122, with one DNA strand in the asymmetric unit. The structure has been refined starting with the earlier lower resolution model and using high-resolution 1.4 Å data collected on a Siemens-Xentronics area detector at 258 K. There were 4365 unique reflections greater than 2σ(F) in the resolution range 5–1.4 Å. The model was refitted into 3Fo − 2Fc. Sim-weighted omit maps and difference maps were used to locate water molecules. The final model with 161 DNA atoms and 37 water molecules gave an R factor of 19.8%. Crystals of the same octamer were also grown in the presence of spermidine instead of spermine, and refinement using nominal 1.45 Å resolution data, 3292 unique reflections, final R = 19.1%, gave virtually identical DNA parameters. No bound spermine or spermidine was detected in either of these structure analyses. The electron density was clear for the DNA and showed holes in the center of the six-membered rings of bases, and also in the center of some of the sugar rings. The high-resolution structure has provided more precise DNA parameters and confirmed the features observed in the earlier 2 Å study including the packing-induced distortion in the A7 (A15) sugar pucker from C(3′)-endo and C(2′)-endo. This change causes the end base pairs to bend away from the helix axis while the rest of the duplex is nearly linear. The hydration patterns in the deep and shallow grooves have been characterized. Chains of water molecules were found, but no rings. The familiar intermolecular contact region between the end base pair and the minor groove of a symmetry-related duplex, involving four residues on one strand and two on the other, has been analyzed. One of these interactions is a hydrogen bond.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444992007522
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  • 3
    Electronic Resource
    Electronic Resource
    Bullatacin, Bullatacinone, and Squamone, a New Bioactive Acetogenin, from the Bark of Annona squamosa (1990)
    s.l. : American Chemical Society
    Journal of natural products 53 (1990), S. 81-86 
    Details
    ISSN: 1520-6025
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/np50067a010
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of Sb on phase transformations of amorphous TiSi2 thin films (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 514-519 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Co-deposited amorphous TiSi2 thin films with various Sb concentrations were prepared in order to study the effects of Sb on TiSi2 phase transformations. The crystallization behavior of the films was investigated by in situ annealing in a transmission electron microscope. The phase transformation from C49 TiSi2 to C54 TiSi2 in the films was examined with x-ray diffraction. It was observed that incorporation of Sb resulted in a higher crystallization temperature of the amorphous TiSi2 film and a lower crystal growth rate. The activation energies for the crystal growth during the crystallization were determined to be 1.37, 1.62, 1.63, and 1.87 eV (±0.07 eV) for the films with 0, 0.3, 1.3, and 2.5 at. % Sb, respectively. For the C49→C54 transformation, it was, however, observed that the activation energy decreased when the Sb content increased. These indicate that the Sb incorporation in TiSi2 retards the crystallization of the amorphous TiSi2 film, but enhances the transformation from C49 TiSi2 to C54 TiSi2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351882
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  • 5
    Electronic Resource
    Electronic Resource
    Thermal stability and crystallization products of amorphous Si:P alloy thin films made by coevaporation of Si and P (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 5179-5184 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thermal stability and crystallization of amorphous Si:P alloy thin films consisting of 20–44 at. % P have been studied in this work. The results show that the alloys have crystallization temperatures ranging from 850 to 1150 °C, which are all higher than that of pure amorphous Si, and that the variation of resistivity of the alloys during the 120 h aging at 300 °C is small (0.6%). These results indicate that the alloys have a high thermal stability, which is in agreement with the thermodynamic prediction we have made. It has also been observed that the crystallization products for these alloys are different. A new silicon phosphide phase has been observed in the 30 at. % alloy sample and suggested to be possibly a hexagonal Si7P3 phase which has lattice parameters a=5.32 A(ring) and c=13.3 A(ring). The alloy films were deposited onto quartz substrates and Si wafers by coevaporation of Si and P. X-ray diffractometry and transmission electron microscopy were utilized to investigate the crystallization temperature and product of the amorphous alloys.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357235
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  • 6
    Electronic Resource
    Electronic Resource
    Optical properties and crystallization of amorphous Si:Sb alloy thin films (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 507-513 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Amorphous Si:Sb alloy thin films with various Sb concentrations were deposited on preoxidized Si substrates in an electron-beam evaporation system. The optical properties and the crystallization of the amorphous alloy as a function of Sb concentration were investigated with spectroscopic ellipsometry and x-ray diffraction (XRD), respectively. It has been found that the optical energy band gap decreases from 1.6 to 0.35 eV with increasing Sb concentration from 0 to 50 at. %, and that the index of refraction decreases overall with the increase of Sb concentration. From the crystallization study, it is seen that the crystallization temperature of the alloy decreases with increasing Sb concentration. From a detailed XRD examination, three different crystallization products from the amorphous alloys have been observed in low, medium, and high Sb concentration regions. The structure of the amorphous alloys and the correlation between the optical properties and the structures of the amorphous alloys are discussed. It is suggested that the amorphous alloys have differing favorable bonding structures, depending on the Sb concentration, that correspond to the bonding structures of the crystallization products.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355830
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  • 7
    Electronic Resource
    Electronic Resource
    Structural and optical band-gap properties of the amorphous semiconducting Si1−xBx alloy (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 891-896 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thin amorphous Si1−xBx films, with x0 ranging from 0 to 0.5, were coevaporated onto preoxidized (100) Si wafers and quartz substrates, by using a dual-electron-gun high-vacuum system. In order to study how the structural and optical properties depended on concentration and annealing temperature, heat treatments of the films were carried out at temperatures from 400 up to 1000 °C. The films were characterized by means of transmission electron microscopy, Auger electron spectroscopy, and spectrophotometry. It is shown that: (i) An amorphous Si1−xBx alloy can exist up to very high temperatures (≥1000 °C), when x is larger than ∼0.4; (ii) at 400 °C the optical band gap of an amorphous Si1−xBx alloy has the maximum value (1.59 eV) for x0=0.02 and then decreases to lower values for higher concentrations (e.g., 1.18 eV for x0=0.3); (iii) the measured optical band gap of amorphous Si1−xBx increases gradually with increasing annealing temperature up to 700–900 °C, and then increases rapidly when annealed at a higher temperature by about 0.5 eV. These changes can be associated with microstructural alterations. The stable amorphous Si1−xBx alloy with x0=0.3 has, for instance, a measured band gap of 1.23 and 1.74 eV after annealing at 800 and 900 °C, respectively. The relationship between the microstructure and the band gap of the films is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354883
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  • 8
    Electronic Resource
    Electronic Resource
    Relationship between molecular marker heterozygosity and hybrid performance in intra- and inter-subspecific crosses of rice (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 118 (1999), S. 0 
    Details
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The objective of this study was to investigate the relationship between molecular marker diversity and heterosis in both intra-and inter-sub-specific hybrids of rice to evaluate the feasibility of predicting hybrid performance using molecular markers. Eleven elite lines were intermated resulting in a diallel set including 10 indica × indica, 15 japonica × japonica and 30 indica × japonica crosses. The F1 hybrids and parents were evaluated for agronomic performance in a replicated field trial. The parental lines were tested for DNA polymorphisms with 113 restriction fragment length polymorphism (RFLP) probes covering the 12 rice chromosomes. Inter-subspecific crosses showed better performance and higher heterosis than intrasubspecific hybrids. Correlations of marker heterozygosity with hybrid performance and heterosis differed considerably between the two subspecies; they were higher in crosses within japonica subspecies than within indica subspecies. Very little correlation was detected in intersubspecific crosses. It was concluded that relationships between marker heterozygosity and hybrid performance were complex owing to germplasm diversity and the complexity of the genetic basis of heterosis. The implications of the results in predicting hybrid performance using molecular markers are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1439-0523.1999.118002139.x
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  • 9
    Electronic Resource
    Electronic Resource
    Pyramiding of insect- and disease-resistance genes into an elite indica, cytoplasm male sterile restorer line of rice,‘Minghui 63′ (2004)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 123 (2004), S. 0 
    Details
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The wild-rice-derived dominant gene Xa21 conferring multi-race resistance to bacterial blight and a fused Bt gene cry1Ab/cry1Ac conferring resistance to lepidopteran insects were individually introduced into the same genetic background of an elite indica cytoplasm male sterile (CMS) restorer line ‘Minghui 63′. The line showed the desirable insect- and disease-resistant phenotypes. To maximize the effect, the two genes were also pyramided into the same recipient plant of ‘Minghui 63’ by marker-assisted selection. After being subjected to natural infestation of leaf-folders and yellow stem borers and inoculation of Xoo strain mixtures, the pyramiding line and its derived hybrids showed high levels of resistance against both insect damage and disease. Furthermore, data from field trials demonstrated that the hybrids made by crossing this pyramiding line with the CMS lines ‘Zhenshan 97A’ and ‘Maxie A’ retained a similar level of yield under conditions without chemical spray, indicating that the pyramiding genes have a yield-stabilizing effect on the recipient line and its hybrids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1439-0523.2003.00917.x
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  • 10
    Electronic Resource
    Electronic Resource
    Optical and electrical investigation of semiconducting amorphous Si:P alloy thin films (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 301-307 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Measurements are reported on the infrared (IR) absorption, the optical band gap, and the dark conductivity of amorphous silicon-phosphorus alloy thin films (a-Si:P) with 20–44 at. % P prepared by coevaporation of Si and P. The results show that the optical band gap can be tailored in a range of 1.5–2.15 eV by varying the P concentration and the annealing temperature. The band gap for the sample with 20 at % P is the widest (1.70–1.82 eV) when annealed at temperatures ≤600 °C. From the IR-absorption study, a stretching mode associated with Si—P bonds at 465–474 cm−1 has been found for all alloy films. An evolution (shift or sharpening) of the Si—P absorption band with annealing temperature and P concentration have also been observed. Based on the IR-absorption study the change of bonding structures in the alloy films is discussed. Conductivity measurements show that two electron conduction processes mainly exist in the investigated temperature range: extended-state conduction in the conduction band at high temperatures and hopping conduction in the band tail at low temperatures. The transition temperature is around room temperature (14–55 °C), indicating that the carriers may mainly drift by hopping even at room temperature. The correlation between the optical band gap and the bonding structure is discussed. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359392
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