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  • Articles  (3)
  • 71.70.-d  (1)
  • Alginate  (1)
  • Alnus  (1)
  • Springer  (3)
  • De Gruyter
  • 1980-1984  (3)
  • 1925-1929
  • 1
    Electronic Resource
    Electronic Resource
    Photoluminescence of AlxGa1−xAs/GaAs quantum well heterostructures grown by molecular beam epitaxy (1984)
    Springer
    Applied physics 33 (1984), S. 97-105 
    Details
    ISSN: 1432-0630
    Keywords: 78.65.-s ; 71.70.-d ; 68.55.+b
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Low-temperature photoluminescence measurements on nominally undoped AlxGa1−xAs/GaAs quantum well heterostructures (QWHs) grown by molecular beam epitaxy (MBE) exemplified the exclusivelyintrinsic free-exciton nature of the luminescence under moderate excitation conditions. Neither any spectroscopic evidence for alloy clustering in the AlxGa1−xAs barriers nor any extrinsic luminescence due to recombination with residual acceptors has been detected in single and double QWHs when grown at 670 °C under optimized MBE growth conditions. Carrier confinement in AlxGa1−xAs/GaAs QWHs starts at a well width ofL z≌30 nm when x≌0.25. The minor average well thickness fluctuation ofΔL z=4×10−2nm as determined from the excitonic halfwidth allowed the realization of well widths as low asL z=1 nm and thus a shift of the free-exciton line as high as 2.01 eV which is close to the conduction band edge of the employed Al0.43Ga0.57As confinement layer. The measurements further revealed a strongly enhanced luminescence efficiency of the quantum wells as compared to bulk material which is caused by the modified exciton transition probabilities due to carrier localization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00617615
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  • 2
    Electronic Resource
    Electronic Resource
    Polymer-entrapped rhizobium as an inoculant for legumes (1982)
    Springer
    Plant and soil 65 (1982), S. 219-231 
    Details
    ISSN: 1573-5036
    Keywords: Alginate ; Carob gum ; France ; Inoculant ; Nodulation ; Polyacrylamide ; Polymer ; Rhizobium japonicum ; Senegal ; Soja ; Xanthan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Field and cylinder experiments conducted in France and in Senegal showed that polyacrylamide, previously proposed as an entrapping gel for preparing Rhizobium inoculants, could be replaced by alginate (AER inoculant) or a mixture of xanthan and carob gum (XER inoculant). Semi-dried or dried AER and XER were used successfully provided that their storage time was less than 90 days. In soil inoculation trails, no marked differences were observed among semi-dried XER, dried AER, and dried XER. A number of seed inoculation experiments indicated that dried XER significantly outranked AER. Seeds preinoculated by up to 48 days with XER yielded plants which were comparable in nodulation and growth parameters to those derived from plant receiving peat inoculation at the time of planting.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02374652
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  • 3
    Electronic Resource
    Electronic Resource
    Alder-Frankia interaction and alder-poplar association for biomass production (1984)
    Springer
    Plant and soil 78 (1984), S. 235-243 
    Details
    ISSN: 1573-5036
    Keywords: Alnus ; Frankia ; N2-fixation ; Mixed stands ; Populus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Alders have an important role to play in biomass producing stands because of their N2-fixing ability and their capacity to withstand soils having an excess of moisture. The objectives of preliminary trials were (1) to find if there is any alder-genotype xFrankia-strain interaction when the effect of inoculating the bacteria was compared to no inoculation in seed beds of different species and provenances of alder, (2) to measure the possible effect of black alders interplanted in poplars compared to pure poplar plots. Two trials were laid out to study the alder-Frankia interaction. Both produced interaction. In the first one the inoculation had a favorable effect onAlnus glutinosa at age 2 years andA. cordata at age 1 and 2 and no effect onA. rubra. In the second one the inoculation had a depressive effect at age 1 on 2 of 3 provenances ofA. rubra and no effect on 1A. rubra, 3A.glutinosa and 3A. cordata provenances. A closely spaced field trial associating one black alder provenance and the poplar clone UNAL gives no superiority of mixed plots compared to pure plots. The results suggest that the N2-fixation of alders is not profitable to poplars at age 3 with a 1.5×2 m spacing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02277854
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