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  • Chemistry  (2)
  • Ace_Lake; Ace Lake, Long Peninsula, Vestfold Hills, East Antarctica; Aluminium; Antimony; Calcium; Chloride; Chromium; Cobalt; Copper; Density meter Anton Paar DMA 55; DEPTH, water; Element analysis, neutron activation (NAA); Gravimetric analysis; Iron; LAKE; Magnesium; Manganese; Nickel; Potassium; Sampling lake; Seawater analysis (Strickland & Parsons, 1972); Selenium; Sodium; Specific gravity; Strontium; Sulfate; Zinc  (1)
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  • 1
    facet.materialart.
    Unknown
    PANGAEA
    In:  Supplement to: Rankin, Lynne M; Gibson, John A E; Franzmann, Peter D; Burton, Harry R (1999): The chemical stratification and microbial communities of Ace Lake, Antarctica: a review of the characteristics of a marine-derived meromictic lake. Polarforschung, 66(1/2), 33-52, hdl:10013/epic.29754.d001
    Publication Date: 2023-01-13
    Description: This article reviews the history, chemical stratification, biology and biogeochemistry of Ace Lake, which is one of the many marine-derived meromictic (permanently stratified) lakes in the Vestfold Hills, Eastern Antarctica. The lake has an area of 18 ha, a maximum depth of 25 m, and a salinity range from 7 to 43 g l**-1. The lake mixes to a depth of 7 m in late winter as a result of brine freeze out during ice formation. Deeper mixing is precluded by a sharp halocline. The water beneath 12 m is permanently anoxic, The lake was formed approximately 10,800 yr BP as the polar ice cap melted. Sea level rise 7,800 yr BP resulted in invasion of seawater into the initially freshwater lake. Subsequently, sea level dropped, and the now saline lake became isolated from the ocean. The biota of the lake was derived from species trapped when the connection between the lake and the ocean was cut off. The oxic zone above 12 m supports a relatively simple community which includes microbial mats, four major species of phytoplankton (including a picocyanobacterium), two copepod species, and a variety of heterotrophic flagellates and ciliates. The anoxic zone contains populations of photosynthetic sulfur, sulfate reducing, fermentative and methanogenic bacteria, which combine to remineralise organic carbon which sediments from the upper waters. Research on the physics, biology and chemistry of Ace Lake has contributed significantly to knowledge of Antarctic meromictic lakes.
    Keywords: Ace_Lake; Ace Lake, Long Peninsula, Vestfold Hills, East Antarctica; Aluminium; Antimony; Calcium; Chloride; Chromium; Cobalt; Copper; Density meter Anton Paar DMA 55; DEPTH, water; Element analysis, neutron activation (NAA); Gravimetric analysis; Iron; LAKE; Magnesium; Manganese; Nickel; Potassium; Sampling lake; Seawater analysis (Strickland & Parsons, 1972); Selenium; Sodium; Specific gravity; Strontium; Sulfate; Zinc
    Type: Dataset
    Format: text/tab-separated-values, 70 data points
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 11 (1988), S. 389-397 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Oxidized beryllium surfaces are used in a number of microwave crossed-field amplifier (CFA) tubes as secondary electron emission cold cathodes. During operation the cathode surface is subjected to electron and ion bombardment in a complex process which produces both erosion and replenishment of the oxide surface, in addition to a significant build-up of amorphous carbon. The result is a general degradation of tube performance. Special techniques were developed to opoen an evacuated tub and transfer the cathode to a UHV surface analysis system with minimal contamination from the atmosphere. Three CFA tubes with various histories of operation were examined and measurements from made of the secondary electron emission (delta), first crossover, voltage at delta maximum, and the surface chemical composition by AES at several points on each cathode. Significant differences were found which reflected their number of hour of operation, as well as variations in manufacturing procedures. A generalized linear cofrrelation between secondary electron emission and the surface carbon atomic fraction was obtained when the data for all the tubes was combined and analyzed. The deleterious effects of carbon in operated CFA tubes were confirmed and suggest that reduction of potential sources of carbon contamination in the tube during manufacture, processing, and operation should improve overall performance.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Cell Biochemistry and Function 2 (1984), S. 186-194 
    ISSN: 0263-6484
    Keywords: Iron ; ferritin ; haemosiderin ; lysosomes ; haemochromatosis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: High levels of haemosiderin occur in iron overload syndromes such as idiopathic haemochromatosis or secondary iron overload in thalassaemic patients; haemosiderin is the predominant iron-storage compound in such cases. It consists of a large aggregate of FeOOH cores, many of which have an incomplete shell of protein, and is probably derived from ferritin by lysosomal proteolysis. In addition, some chemical degradation of the ferritin cores appears to occur on conversion to haemosiderin. Other biochemical components are phosphate and magnesium, which may be adsorbed to the core surface, and perhaps certain lipids. Haemosiderin may have a central role, either directly or indirectly, in iron cytotoxicity and therefore the chemistry and biochemistry of this material warrants further study.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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