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  • 1
    ISSN: 1432-2242
    Keywords: Apparent Km ; Glutathione reductase ; Onobrychis spp. ; Sainfoin ; Thermal kinetic window
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Understanding the biochemical and physiological consequences of species variation would expedite improvement in agronomically useful genotypes of sainfoin (Onobrychis spp.) Information on variation among sainfoin species is lacking on thermal dependence of glutathione reductase (B.C. 1.6.4.2.), which plays an important role in the protection of plants from both high and low temperature stresses by preventing harmful oxidation of enzymes and membranes. Our objective was to investigate the interspecific variation for thermal dependency of glutathione reductase in sainfoin. Large variation among species was found for: (i) the minimum apparent Km (0.4–2.5 μM NADPH), (ii) the temperature at which the minimum apparent Km was observed (15°–5°C), and (iii) the thermal kinetic windows (2°–30°C width) over a 15°–45°C temperature gradient. In general, tetraploid species had narrower (≤17°C) thermal kinetic windows than did diploid species (∼30°C), with one exception among the diploids. Within the tetraploid species, the cultivars of O. viciifolia had a broader thermal kinetic window (≥7°C) than the plant introduction (PI 212241, 〉2 °C) itself.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2242
    Keywords: Esterase ; Onobrychis spp. ; Polymorphism ; Sainfoin ; Similarity index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Understanding polymorphism at the enzyme level is basic to its use in population and genetic studies. However, no such information is available on the variability among different sainfoin (Onobrychis) species. Therefore, our objective was to study the existence of genetic polymorphism for esterase in 17 Onobrychis species and three cultivars of O. viciifolia Scop. Three regions of banding were observed in all the materials tested, with the number of bands varying from 0 to 3, 3 to 14, and 1 to 2 bands in each of these zones, which have been designated EST1, EST2, and EST3 respectively. All the materials studied had unique banding patterns, the only common feature being that all of them, except one species, had isozyme 1. Identification was possible only for four species (O. iberica, O. kachetica, O. transcaucasica, and O. bieberstenii) and one cultivar (‘Nova’) based on the banding patterns. Large diversity was evident from the wide range of percent similarity values (0%–79%). Subsequent studies should be directed in using these isozyme banding patterns as markers to the desirable agronomic and quality traits of different germplasm lines.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: An investigation was made of the influence of application techniques on the microstructure and properties of an acrylic tooth restorative. Mixtures of acrylic powder and monomer (“Sevriton Simplified”) were applied by the brush technique of Nealon (J. Prosth. Dent., 2, 513, 1952) and by two bulk flow techniques. While similar porosities (about 4%) were observed, the brush technique resulted in a greater quantity of grains from the acrylic powder. Despite this, there was little difference in values of compression modulus, compressive yield stress, and diametral compressive strength.The mechanical strength of the materials studied was less than one-half that of high molecular weight poly (methyl methacrylate) (PMMA). Crack propagation studies established that the interface between the grains and matrix was not a source of weakness. However, as the matrix was crosslinked this could not be checked by solution methods of polymer characterization.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Irrigation science 14 (1994), S. 199-205 
    ISSN: 1432-1319
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The threshold canopy temperature method for controlling a drip irrigation system includes a physiologically based threshold temperature and irrigation application rate that responds to the environment. Energy input from the environment causes canopy temperature to exceed the threshold value and irrigation is then applied. This study evaluated temperature distributions, amount of optimum time, and the amount of irrigation control time for cotton where irrigation scheduling was controlled by different threshold temperatures during the years 1988 to 1991. Optimum time for cotton growth was defined as the accumulated time that canopy temperatures were between 25 and 31 °C and the time accumulated above different threshold temperatures was designated as irrigation control time. Threshold temperatures over a 26 to 32 °C range altered the frequency distribution of temperature within the optimum temperature range (25–31 °C) by reducing temperatures above the threshold. Frequency of canopy temperatures of a 28 °C threshold temperature treatment decreased in the 28 to 29 °C increment and then remained below air temperature. Irrigation control time was more sensitive than optimum time to changes in threshold temperature between 26 and 31 °C. Optimum time and irrigation control time of the 28 °C threshold temperature varied by 37% and 29%, respectively. Lint yields in 1988 and 1990 were high while those in 1989 and 1991 were low because of unfavorable weather. Irrigation amounts applied during DOY 198–273 that were above 20 cm in high yield years or 12 cm in low yield years did not increase yield.
    Type of Medium: Electronic Resource
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  • 5
    Publication Date: 2011-08-19
    Description: A new method is described for deducing the thermal-acoustic efficiency spectrum (defined as the fraction of combustion heat release converted to acoustic energy at a given frequency) of a long turbulent burner from the sound spectrum measured in the far field. The method, which is based on a one-dimensional model of the unsteady flow in the burner, is applied to a tubular diffusion-flame hydrogen burner whose length is large compared to its diameter. The results for thermal powers ranging from 4.5 to 22.3 kW show that the thermal-acoustic efficiency is relatively insensitive to the burner power level, decreasing from a value of around 0.0001 at 150 Hz with a slope of about 20 dB per decade. Evidence is presented indicating that acoustic agitation of the flame below 500 Hz, especially in the neighborhood of the resonant frequencies of the burner, is a significant acoustic source.
    Keywords: ACOUSTICS
    Type: (ISSN 0379-380X); 4, 19; 95-105
    Format: text
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  • 6
    Publication Date: 2019-07-12
    Description: The residence time of the combustible mixture in the combustion chamber of a scramjet engine is much less than the time normally required for complete combustion. Hydrogen and hydrocarbon fuels require an ignition source under conditions typically found in a scramjet combustor. Analytical studies indicate that the presence of hydrogen atoms should greatly reduce the ignition delay in this environment. Because hydrogen plasmas are prolific sources of hydrogen atoms, a low-power, uncooled hydrogen plasma torch has been built and tested to evaluate its potential as a possible flame holder for supersonic combustion. The torch was found to be unstable when operated on pure hydrogen; however, stable operation could be obtained by using argon as a body gas and mixing in the desired amount of hydrogen. The stability limits of the torch are delineated and its electrical and thermal behavior documented. An average torch thermal efficiency of around 88 percent is demonstrated.
    Keywords: INORGANIC AND PHYSICAL CHEMISTRY
    Type: Journal of Propulsion and Power (ISSN 0748-4658); 5; 129-133
    Format: text
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  • 7
    Publication Date: 2019-07-12
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Aircraft (ISSN 0021-8669); 23; 142-147
    Format: text
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  • 8
    Publication Date: 2019-07-10
    Description: The current effort addresses two issues important to the research conducted by the Thermal Radiation Group at Virginia Tech. The first research topic involves the development of a method which can properly model the diffraction of radiation as it enters an instrument aperture. The second topic involves the study of a potential next-generation space-borne radiometric instrument concept. Presented are multiple modeling efforts to describe the diffraction of monochromatic radiant energy passing through an aperture for use in the Monte-Carlo ray-trace environment. Described in detail is a deterministic model based upon Heisenberg's uncertainty principle and the particle theory of light. This method is applicable to either Fraunhofer or Fresnel diffraction situations, but is incapable of predicting the secondary fringes in a diffraction pattern. Also presented is a second diffraction model, based on the Huygens-Fresnel principle with a correcting obliquity factor. This model is useful for predicting Fraunhofer diffraction, and can predict the secondary fringes because it keeps track of phase. NASA is planning for the next-generation of instruments to follow CERES (Clouds and the Earth's Radiant Energy System), an instrument which measures components of the Earth's radiant energy budget in three spectral bands. A potential next-generation concept involves modification of the current CERES instrument to measure in a larger number of wavelength bands. This increased spectral partitioning would be achieved by the addition of filters and detectors to the current CERES geometry. The capacity of the CERES telescope to serve for this purpose is addressed in this thesis.
    Keywords: Environment Pollution
    Format: application/pdf
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  • 9
    Publication Date: 2019-07-13
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Conference on Atmospheric Radiation; Aug 07, 1972 - Aug 09, 1972; Fort Collins, CO
    Format: text
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  • 10
    Publication Date: 2019-07-12
    Description: The Earth Radiation Budget Experiment consists of an array of radiometric instruments placed in earth orbit by the National Aeronautics and Space Administration to monitor the longwave and visible components of the earth's radiation budget. Presented is a dynamic electrothermal model of the active cavity radiometer used to measure the earth's total radiative exitance. Radiative exchange is modeled using the Monte Carlo method and transient conduction is treated using the finite element method. Also included is the feedback circuit which controls electrical substitution heating of the cavity. The model is shown to accurately predict the dynamic response of the instrument during solar calibration.
    Keywords: GEOPHYSICS
    Type: Applied Optics (ISSN 0003-6935); 28; 1327-133
    Format: text
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