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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 2777-2784 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The Perth Astronomy Research Group has developed an automated supernova search program, using the 61 cm Perth–Lowell reflecting telescope at Perth Observatory in Western Australia, equipped with a CCD camera. The system is currently capable of observing about 15 objects per hour, using 3 min exposures, and has a detection threshold of 18th–19th magnitude. The entire system has been constructed using low-cost IBM-compatible computers. Two original discoveries (SN 1993K, SN 1994R) have so far been made during automated search runs. This paper describes the hardware and software used for the supernova search program, and shows some preliminary results from the search system. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 52 (1997), S. 0 
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The effects of temperature on silage effluent production were examined. In the first experiment, samples of perennial ryegrass (Lolium perenne) underwent fermentation at 20°C for between 52 and 66 d. The samples were then transferred to rooms at temperatures between 5°C and 27°C. Effluent production during creep consolidation was measured. Increasing temperature resulted in a significant increase in effluent production. There was a strong linear relationship between the mechanical properties of the silage and the amount of effluent produced. In the second experiment, Italian ryegrass (Lolium multiflorum) samples were ensiled at temperatures between 5°C and 25°C. The higher temperature treatments had faster and more extensive fermentations, and produced more effluent than the cooler temperatures. Again, there was a strong linear relationship between the mechanical properties of the silage and the amount of effluent produced. Increasing the temperature at the end of the experiment resulted in no extra effluent production from any treatment except that at 5°C. This indicated that the effects of temperature were evident only while effluent was available for release. The effects of temperature will therefore be most evident in the early stages of ensilage. In both experiments, effluent was released from the higher temperature treatments earlier. This was probably due to the effects of temperature on the viscosity of the effluent and to fermentation effects in the second experiment. In both experiments, the increase in effluent production with temperature was equivalent to the effects to be expected from decreasing the herbage dry matter concentration by between 3% and 4%.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 50 (1995), S. 0 
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The suitability of freezing a large amount of grass from a single harvest for use in a series of experiments to investigate silage fermentation and its manipulation was examined. Perennial ryegrass, harvested in late June, was ensiled in sterile polythene bags inside an anaerobic cabinet; some was also stored frozen at -20°C for up to nine months before ensiling in a similar manner. The course of fermentation was followed using not only conventional chemical and microbiological analyses, but also by measuring microbial metabolic activity in vitro. Freezing and thawing affected the chemical composition and the microbial populations on the grass, and there were differences in the changes occurring in thawed grass during ensilage, probably related to damage to plant cells and impaired microbial activity associated with freezing and thawing. For both the grasses and the silages made from them, it was clear that the number of microorganisms present was not a reliable guide to microbial metabolic activity. Although the fermentation of frozen-and-thawed grass did not simulate precisely the fermentation occurring with fresh grass, it is concluded that, when used judiciously, the ensilage of thawed grass can be a useful experimental tool, particularly in the initial screening of manipulants of fermentation.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Grass and forage science 52 (1997), S. 0 
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Direct-cut grass silage was ensiled without compression in laboratory silos for 0–75 d. On occasions during this period, the silage was subjected to creep compression tests at three pressure levels for a period of 5 h and effluent production was measured. Precision-chopped Italian ryegrass (Lolium multiflorum) was ensiled in the first experiment, whereas flail-harvested perennial ryegrass (Lolium perenne) was ensiled in the second. Pressure levels were 11·3, 16·9 and 22·5 kPa for Experiment 1 and 5·7, 11·3 and 16·9 kPa for Experiment 2. Moisture contents of the ensiled herbage were 815 and 856 g kg−1 for Experiments 1 and 2 respectively. The consolidation of the grass silage was described by a Burgers body model. Effluent production was more closely related to strain than to compressibility. Linear regression equations for the relationship between strain and effluent production are presented. There was a significant positive linear relationship between pressure and effluent production at each silo opening time in both experiments. The time course of effluent production was fitted to a negative exponential curve. The time that elapsed before effluent release in each experiment was a function of both pressure and time after ensilage. The results of the experiments were compared with the predictions of two models of effluent production. Reasonable agreement between predicted and actual effluent production could be obtained provided the measured material parameters were used and immediate saturation of the forage was assumed. Using the models highlighted the need for a better understanding of saturation development in the silage.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 2781-2787 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of ion implantation and ultrasonic cavitation on the near-surface region of MgO single crystals were investigated. For 150 keV, room-temperature implantations of Ar+ or K+ at 5×1016–1017 ions cm−2 into a (100)-oriented surface of MgO, a dilatometric swelling of the implanted layer is observed perpendicular to the implanted surface. When these strained surface layers are then subjected to an ultrasonic (∼20 kHz) cavitation treatment, uniform layers (∼100–200 nm) can be removed from the MgO surface in a controlled manner. The thickness of the removed layer is directly related to the duration of the ultrasonic irradiation, but does not exceed the depth of the implanted species. When MgO implanted with Ar+ or Kr+ at fluences of 5×1016–1017 ions cm−2 is subsequently irradiated with 2 MeV He+ ions at 1016–1017 ions cm−2, the region exposed to the He+ beam is effectively "stabilized'' and is not removed by the ultrasonic treatment. K+ or Ar+ implantations at 〈5×1016 ions cm−2 produced no swelling of the layer, and subsequent ultrasonic irradiation with an energy flux of ∼120 W cm−2 did not remove the crystal surface as determined by profilometry. For MgO implanted with (approximately-greater-than)2×1017 ions cm−2, the implanted layer is highly strained and detaches from the underlying crystal without exposure to ultrasonic-cavitation effects. These findings are discussed in terms of the stressed states of the implanted layers, and their potential applications to the mechanical "etching'' of ceramics are considered.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 46 (1924), S. 1184-1196 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 46 (1924), S. 1178-1183 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 756 (1995), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 4756-4759 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: BH4, with isotopic substitution, has been prepared and trapped in solid H2, D2, HD by laser vaporization of boron and subsequent reaction with the matrix gas. The results confirm the C2v structure of the molecule and generally support the results of Symons et al., on γ-irradiated NaBH4. Differences from those results are discussed, and comparison is made with the CH4+ parameters of Knight et al.© 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Sedimentology 42 (1995), S. 0 
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: A new quantitative method for characterizing quartz grain shape is presented. The method employs a harmonic analysis based upon Fourier descriptors which is a distinct variation of the traditional and widely used Fourier series. Quartz grain images from a scanning electron microscope were ‘frame grabbed’and converted to a digitized grey-level image. The image processing techniques of enhancement, segmentation and boundary tracking were applied to remove all features except the image boundary. This boundary was sampled at uniform intervals of are length and represented mathematically on the complex plane. In this way problems associated with the location of particle centroid and re-entrant values were avoided. The resulting data was standardized relative to scale, rotation and starting position. Hence the discrete Fourier transform was applied using modern fast Fourier transform techniques and the modulus of the resulting harmonic amplitude used to characterize the grain shape. The technique was applied to a sample of 0–5-m quartz grains from three distinct populations: desert quartz, beach grains (Fire Island, New York) and Brazilian crushed quartz. Whilst plots of average amplitude vs. harmonic number for each population appeared similar, discriminant analysis applied to each grain sample distinguished characteristic grain shape with an excellent degree of success. The problems of location of the centroid and re-entrant values were eliminated. This allowed the technique to be applied to a much wider group of irregularly shaped sedimentary particles such as loess.
    Type of Medium: Electronic Resource
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