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  • Chemical Engineering  (2)
  • Conference proceedings  (2)
  • Male germ unit  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 17 (1995), S. 1791-1795 
    ISSN: 0392-6737
    Keywords: Time-resolved optical spectroscopies and other ultrafast optical measurements in condensed matter ; III–V semiconductors ; Conference proceedings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary Exciton dynamics including thermalisation, radiative recombination and migration in growth-interrupted and hydrogen-passivated GaAs/AlAs single quantum wells have been investigated under non-resonant and resonant excitation.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 17 (1995), S. 1625-1628 
    ISSN: 0392-6737
    Keywords: Time-resolved optical spectroscopies and other ultrafast optical measurements in condensed matter ; III–V compounds and systems ; III–V semiconductors ; Conference proceedings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary Low-temperature PL decay times, τPL, measured for a series of In x Ga1−x As/GaAs quantum wells (QWs) show an almost linear increase with increasing thickness (4≤L z ≤10 nm,x=0.15) and with increasing In composition (0.05≤x≤0.25,L z =8 nm). τPL also increases linearly with temperature up to 50K, as expected for free excitons and does not exhibit the interface effects seen for GaAs/AlGaAs QWs. Wells with different In compositions exhibit a similar temperature behaviour and there is a weak influence of strain on the decay time.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2145
    Keywords: Cymbidium goeringii ; Cytoplasmic diminution ; Generative cell ; Male germ unit ; Vegetative nucleus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Pollinia of Cymbidium goeringii (Orchidaceae) were examined at a young stage (approx. 2 weeks before anthesis) and at anthesis using transmission electron microscopy, computer-assisted serial reconstruction and quantitative cytology. At the young stage, the generative cell (GC) has a spherically shaped main body with a large nucleus and 1 to 4 cytoplasmic extensions (up to 10 μm long) physically associated with a groove on one side of the vegetative nucleus (VN). By anthesis, some GCs lose their cytoplasmic extensions, becoming spherical. The GC surface becomes highly wrinkled, the distance between the GC and the VN increases and the two may separate completely. Enucleated cytoplasmic bodies (ECBs) are apparently generated by the GC, as evidenced by their similar ultrastructural appearance and distribution near the GC. ECBs are likely produced from two sites: the GC surface and the tips of cytoplasmic extensions of the GC. Vesicle-containing bodies (VCBs) may be generated from the lateral surface of the GC and may also represent a degeneration stage of ECBs, finally fusing with lipid bodies. Heritable organelles are rare and usually absent in the GC of Cymbidium: 0.176 mitochondria and 0.0042 plastids per GC were observed at the young stage and no mitochondria and 0.019 plastids at anthesis. Of 16 cellular parameters examined during GC development, all decreased with the exception of the surface area and volume of ECBs/ VCBs (which remained stable) and GC vacuoles (which increased). Significant decreases in 11 parameters presumably relate to dehydration of the pollen and male cytoplasmic diminution.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1615-6102
    Keywords: Cytoplasmic inheritance ; Male cytoplasmic diminution ; Male gamete (angiosperm) ; Male germ unit ; Nicotiana ; Tobacco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The organization of the sperm cells and vegetative nucleus (male germ unit) ofNicotiana tabacum was examined 18 h after semivivo pollination using transmission electron microscopy, computerassisted serial section reconstruction and quantitative cytology. Based on a measurement of 11 cellular parameters in nine reconstructed sperm cell pairs, there are no statistically significant differences between the two cells. The Svn is characterized by a strapshaped cytoplasmic extension that is physically associated with the surface of the vegetative nucleus. The nucleus is located adjacent to the sperm crosswall, with sperm organelles being distributed between the nucleus and the extension. The Sua is a tapered cell with cytoplasmic areas at both poles and deep axial invaginations near the crosswall. This cell has a centrally-located nucleus and a largely polar distribution of organelles. Three mechanisms for cytoplasmic diminution were observed that appear to contribute actively to the loss of cytoplasmic volume and organelles: (1) enucleated cytoplasmic body production in the Sua; (2) vesiculation at the tip of the cytoplasmic projection of the Svn; and (3) vesicle-containing body accumulation in the periplasm of both the Svn and Sua.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 16 (1970), S. 588-594 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The heat and mass transfer processes in a binary mixture flowing in a parallel plate channel with mass addition at the bounding surfaces are investigated analytically. The rate of mass addition, the temperature, and the mass fraction are arbitrarily prescribed at each of the bounding walls. Similarity solutions are evaluated numerically to yield pressure gradient, Nusselt number, and Sherwood number results for a wide range of each of three governing parameters. It is found that increasingly strong surface mass addition markedly increases the magnitude of the axial pressure gradient. Mass addition decreases the Nusselt and Sherwood numbers at the channel wall at which the injection is strongest but may actually increase these moduli at the opposite wall. A generalizing analysis is performed to accommodate phase change processes as well as to accommodate the specification of plenum conditions rather than wall surface conditions. Application is made to the evaporation of liquid water by an air stream. It is shown that the rate of evaporation is augmented as the rate of air injection increases, but the extent of the augmentation is less than the causative increase in the air flow rate.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 13 (1967), S. 10-16 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A method of analysis is presented for determining closed-form solutions for two-component stratified laminar flow in horizontal ducts of arbitrary cross section. It is demonstrated that the method is remarkably easy to apply and produces results of high accuracy. As an application, solutions are obtained for stratified flow in a circular tube. The results are compared with various limiting cases and excellent agreement is found to exist. Among the limiting cases, an exact solution was derived by Green's functions for the problem in which the interface between the flow components is situated at the horizontal diametral plane.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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