Browsing by Author "Sanderson, R. D."

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    Advantages of scanning probe microscopy in polymer science
    (Academy of Science for South Africa, 2004) Meincken, M.; Sanderson, R. D.
    We introduce the atomic force microscope (AFM) and its capabilities with special regard to its use in polymer science. It shows several advantages over other analytical techniques, such as scanning electron microscopy, differential scanning calorimetry, and dynamic mechanical analysis. Its main advantage is that the samples need not be prepared specially and can therefore be studied in their native environment. Further-more, the AFM can be used to detect physical properties locally on a molecular scale, which may be of interest for characterizing polymer blends or structured polymers.
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    Analysis of gamma-ray and neutron-induced chromosome aberrations in CHO-K1 cells using the atomic force microscope
    (Academy of Science for South Africa, 2004) Meincken, M.; Smit, B. S.; Sanderson, R. D.; Slabbert J. P.
    THE ENUMERATION OF CHROMOSOME aberrations remains a popular method to relate DNA damage to radiation dose delivered, and is the basis of efforts to improve aberration assays. In the work reported here, atomic force microscopy was used to study the induction of chromosome aberrations in CHO-K1 cells, after irradiation with 1-3 Gy p(66)/Be neutrons and 2-7 Gy 60Co γ-rays. The investigation showed that small structures, not normally well defined using conventional microscopy, can be resolved and identified with the atomic force microscope. Furthermore, the height information gathered by atomic force microscopy is useful for eliminating counting mistakes, which might be caused by chromatid or chromosome overlaps. The superior resolution of atomic force microscopy over conventional optical microscopy renders the scoring of as few as 20 cells per dose point as sufficient to draw accurate dose curves that correctly express the biological damage induced by different radiation sources.
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    Infrasonic backpulsed membrane cleaning of micro- and ultrafiltration membranes fouled with alumina and yeast
    (Water Research Commission, 2013) Shugman, E.; Aldrich, C.; Sanderson, R. D.; McLachlan, D. S.
    Membrane fouling is universally considered to be one of the most critical problems in the wider application of membrane filtration. In this research microfiltration and ultrafiltration membranes were fouled during a cross-flow filtration process, using yeast and alumina suspensions in a flat cell. Infrasonic backpulsing directly into the permeate space was then used to clean the membrane, using both permeate water and soap solutions. Ultrasonic time domain reflectometry (UTDR) was used to detect and measure the growth of fouling on membrane surfaces, during the filtration and cleaning processes. The objective of this work was to examine the efficiency of back-pulse cleaning, using different combinations of membrane materials and foulants, in flat cells. The results show that a flux value of between 60% and 95% of the clean water value can be recovered after cleaning, by using a sequence of three 6.7 Hz backpulses, each pulse being 35 s long with a peak amplitude of about 140 kPa.
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    The removal of copper and iron from wine using a chelating resin
    (South African Society for Enology and Viticulture, 1986) Loubser, G. J.; Sanderson, R. D.
    An insoluble polymer-supported absorbant, developed for the selective removal of excess copper and iron from wine was tested. Tests conducted on dry white wine with excessive copper and iron showed effective removal of 98% copper (II) and 82 % iron (III). This treatment did not significantly affect the other wine constituents and therefore offers an appropriate alternative to the ferrocyanide treatment.