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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 1776-1783 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The dependence of structural parameters and force constants for Cu–Se, Ga–Se, and In–Se bonds on compositional deviations in CuIn0.5Ga0.5Se2 have been studied. The composition gradient along the ingot was obtained by a single fusion at 1150 °C of the components and subsequent slow cooling in a still ampoule placed in a vertical furnace. All along the sample, a single chalcopyrite phase is present and its composition along its length was found by energy dispersive analysis of x-ray measurements on slices. Unit cell parameters, anion displacement, and Cu occupation fraction in its sublattice were analyzed by x-ray powder diffraction and Rietveld refinement methods. The anion displacement found is a function of the Cu defect in its sublattice. The existence of associated defects, i.e., two Cu vacancies and one Ga in Cu site, [2V(Cu)+GaCu], is proposed to explain the Cu defect in its sublattice and the changes in lattice parameters. This leads to the existence of BIII vacancies (BIII=In+Ga), and interstitial Cu up to 8 at. % that also cause changes in the structural parameters. Infrared reflectance measurements led to the imaginary dielectric constant determination which, fitted to a Lorentz function, permitted to obtain atomic vibration modes. Using the model of Neumann for chalcopyrites, the values of force constants for Cu–Se, Ga–Se, and In–Se bonds were computed. These appear to increase when the occupation of each sublattice increases. © 2000 American Institute of Physics.
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 5610-5616 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: By x-ray powder diffraction and the Rietveld refinement method, the atomic positions in CuInSe2 were determined for compositions close to stoichiometry. The Se position, x(Se), was found to be correlated to the Cu content. According to a model proposed by Jaffe and Zunger [Phys. Rev. B 29, 1882 (1984)], changes in x(Se) induce a variation in the optical band gap, Eg. This could explain the spread in energy gap, Eg, found by many authors for this compound. The increase in the lattice parameter, a, correlated with the difference between the energy dispersive analysis of x rays and x-ray diffraction determined Cu contents, suggests the presence of a fraction of Cu atoms as interstitials. © 1996 American Institute of Physics.
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 616-618 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A method to obtain the band gap energy value from reflectance measurements has been developed for bulk materials with direct and indirect gaps. In an energy region around the gap value, the experimental reflectivity is fitted by two functions of the type R=A0+A1′(1/hν)2−A1′Eg×(1/hν)3 and R=A0+B[(hν−Eg)/(hν)]4, for direct and indirect transitions, respectively, in an energy range around the gap value. This implies that the absorption coefficient, α, shows a dependence with the energy α=(A/hν)(hν−Eg)m with m=1/2, 2 for direct and indirect gaps, respectively. The method has been checked in several materials of known energy gaps including Si and Ge. © 1998 American Institute of Physics.
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 1995-2002 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Indium tin oxide thin films consisting mainly of whiskers have been deposited on glass by electron beam evaporation. Low deposition rates (35 Å/min) and substrate temperatures in the 120–400 °C range were used. Morphology by scanning electron microscopy, crystal structure, energy dispersive analysis of x-rays, and x-ray photoelectron spectroscopy compositions, optical and conducting properties of films have been studied as a function of temperature of growth and further annealing in air. Whiskers associate and produce flatter surfaces, the grain size increases from (approximate)390 Å to (approximate)790 Å, keeping however its fibrous structure after 400 °C-30 min annealing. In films deposited at temperatures below 200 °C, next to cubic In2O3, tetragonal Sn and cubic In2Sn2O(7−x) appear. During growth and after air annealing Sn4+ segregates to the surface, attaining Sn/In concentration ratios of 4.6. On air annealing the optical transmittance and electrical resistance increase, in some cases from 2% to 90% and by a factor of about 4, respectively. © 1998 American Institute of Physics.
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of chemical & engineering data 25 (1980), S. 80-83 
    ISSN: 1520-5134
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 6
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of organic chemistry 58 (1993), S. 6122-6125 
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
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  • 7
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The effects of pre-planting solarization or fumigation with metham-sodium of sand-mulched soil on fusarium wilt of watermelon in plastic house culture were investigated at Almeria, south-eastern Spain. In two trials, 2 months' solarization increased the average maximum soil temperature by c. 5°C to 44-48° C at 10 cm depth and by 4-5° C to 40-42° C at 20-30 cm. The amount of Fusarium oxysporum in the upper 15 cm of a naturally infested soil was reduced by solarization and by fumigation. During the 9 months following treatment, the F. oxysporum population stabilized at a low level in soil solarized for 2 months, but fluctuated in soil solarized for 1 month and increased in fumigated soil. The amount of wilt in watermelon sown into this soil after treatment was generally low; plants growing in solarized or fumigated soil suffered less wilt than plants in untreated soil but the differences were not significant. In a soil artificially infested with the highly pathogenic race 2 of F. oxysporum f. sp. niveum, F. oxysporum populations were greatly reduced following solarization or fumigation, and fluctuated erratically thereafter. Solarization for 2 months completely controlled wilt in watermelon and gave a fruit yield almost five times that of plants in untreated soil. Solarization for 1 month only slowed disease development slightly but gave a yield more than twice that in untreated soil. Fumigation with metham-sodium retarded disease development considerably and tripled fruit yield. Plant performance was significantly better in soil solarized for 2 months than in uninfested control soil, suggesting beneficial effects of this treatment additional to wilt control.
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant pathology 37 (1988), S. 0 
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The phenology of Verticillium albo-atrum (Vaa) sporulation on infected tissues and the presence of Vaa in the air were investigated in alfalfa fields affected by verticillium wilt (VW) during the 1983/84 growing season. Few and scattered Verticillium conidiophores developed on stubble by the end of May, but abundant Verticillium sporulation was found on necrotic leaflets and petioles by the beginning of June at the first appearance of symptoms. Abundant conidiophores developed also on necrotic stems and leaf tissues sampled later. Sporulation was never found on entirely green stems. Concentration of airborne colony-forming units (cfu) of Vaa ranged from 0.0 to 15.3 cfu/m3 above fields with a VW incidence of 2.2-33.0% in June and August, and from 5.9-25.9 cfu/m3 during mowing of the crop in August. The ratio of Vaa to other airborne fungi above sampled fields was less than 5 x 10-3, Airborne fungi were even more abundant at the time of mowing. Our results suggest that airborne V. albo-atrum may not play an important role in the epidemiology of VW of alfalfa.
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, U.K. and Cambridge, USA : Blackwell Publishers
    Plant pathology 47 (1998), S. 0 
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Four populations of Pratylenchus thornei from different locations were tested for reproductive fitness in axenic carrot disc cultures and for pathogenicity to chickpea cultivars JG 62 and UC 27 and lines K 850 and ILC 1929. Parasitism and histopathology on selected chickpea genotypes (JG 62, UC 27 and lines ILC 482, ICC 11324 and ICC 12237) were also investigated. Reproductive fitness, assessed as the ratio of the final number of nematodes per carrot disc to the number of nematodes inoculated, was similar among the populations tested and the four populations reproduced to a similar extent in a given chickpea genotype. However, the extent of reproduction was significantly affected by the chickpea genotype, JG 62 and UC 27 being the best and poorest hosts, respectively. Pathogenicity to chickpea genotypes was assessed by the difference in fresh root and dry shoot weights between infected and uninfected plants 90 days after inoculation. Plant growth was significantly reduced by the four nematode populations in all chickpea genotypes, with the exception of cv. JG 62, which was tolerant of P. thornei. Severity of root necrosis caused by nematode infection was similar for all populations. Histopathological studies of chickpea genotypes infected by P. thornei showed that all were suitable hosts according to nematode reproduction and host reaction. P. thornei always migrated through epidermal and cortical cells by breaking down cell walls along the nematode pathway. In the most susceptible lines (ILC 482 and JG 62), damage to endodermal cells adjacent to nematode feeding sites was occasionally observed.
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, U.K. and Cambridge, USA : Blackwell Science Ltd
    Plant pathology 45 (1996), S. 0 
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Egg hatch of Pratylenchus thornei was influenced by temperature. It took place at all temperatures within the range 10–25°C and was optimal at 20°C. Root penetration increased steadily with increasing time of incubation up to the end of the experiment 11 days after inoculation. Temperature affected penetration rate in chickpea (Cicer arietinum) cultivars UC 27 and JG 62 but not in line P 2245, being significantly higher at 20–25°C than that at 15°C. At the end of the experiment, roots of line P 2245 held at 15°C contained more P. thornei than cultivars UC 27 and JG 62. No difference in percentage penetration among host genotypes was observed at 20 or 25°C. All migratory stages of P. thornei penetrated roots of chickpea from the first to 11th days after inoculation.
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