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[en] After reporting briefly on leaching with Thiobacillus, it is discussed whether in those cases where thiobacilli fail to work the limits of microbial leaching are reached or still other groups of microorganisms will be suitable. In this relation the great number of carbon-heterotrophic fungi and bacteria have to be considered which are partly oligotrophic and occur e.g. in weathering biotopes of rocks and minerals and which may even include heavy metals in the dissolving processes of weathering. The active agents are, as far as is known up to now, organic acids which are produced by microorganisms and given off to the medium where they may combine with metals to form water-soluble complex compounds. In order to detect and isolate suitable strains of fungi and bacteria it will be necessary to work out a screening program which proceeds from general to special selections. Experiments to identify the active agents and the conditions of their production will have to follow. It remains still an open question whether such studies will result in technical processes. Mass production processes which are possible with the carbon-autotrophic and acidophilic thiobacilli are less probable than special processes to get hold of rare and economically valuable metals whose extraction would be difficult by other means. (orig.)
[de]
Nach einem kurzen Hinweis auf die Laugung mit Thiobacillus-Arten wird diskutiert, ob in den Faellen, in denen Thiobacillus versagt, die Grenzen mikrobieller Laugungsmoeglichkeiten erreicht sind oder ob auch andere Gruppen und Arten von Mikroorganismen in Frage kommen, wobei vor allem an die grosse Zahl kohlenstoff-heterotropher, zum Teil ernaehrungsphysiologisch anspruchsloser (obligotropher) Bakterien und Pilze zu denken waere, wie sie z.B. in Verwitterungsbiotopen von Gesteinen und Mineralien auftreten und selbst Schwermetalle in den Loesungsprozess einbeziehen koennen. Wirksam sind, soweit bis jetzt bekannt, organische Saeuren, die von den Mikroorganismen an das Medium abgegeben werden und mit Metallen wasserloesliche Komplexe bilden. Zum Nachweis und zur Isolierung geeigneter Staemme von Pilzen und Bakterien ist es erforderlich, ein screening-Programm zu entwickeln, das von allgemeinen zu speziellen Fragestellungen fortschreitet. Versuche zur Identifizierung der wirksamen Agentien und ihrer Entstehungsbedingungen muessen sich anschliessen. Desgleichen sind Untersuchungen ueber die Aufzucht wirksamer Mikroorganismen in organischen, oekonomisch tragbaren Medien erforderlich. Es bleibt noch offen, ob sich aus derartigen Untersuchungen Ansaetze fuer technische Verfahren ergeben werden. In Frage kaemen weniger Massenverfahren zur Verwertung minderwertiger Erze, wie es im Thiobacillus-Bereich moeglich ist, als spezielle Verfahren zur Erfassung seltener, wirtschaftlich wertvoller und auf andere Weise schwer zu gewinnender oder schwer aus Gemischen abtrennbarer Metalle. (orig.)Journal
Metall; ISSN 0026-0746; 
; v. 34(9); p. 847-850
; v. 34(9); p. 847-850
[en] In a series of laboratory studies, we determined the solid to liquid distribution coefficient, Kd, for iodine (125I) in Canadian Shield lake sediments and the loss rate of 125I from water to sediment for more accurate computer model predictions of the fate of 129I released from an underground disposal vault. The Kd values were determined under oxic and anoxic (reducing) conditions at sediment-to-water ratios of 1, 10 and 50% for organic sediment, peaty sediment, clayey silt/sand sediment and sand sediment. (author)
Journal
[en] The diagnostic usefulness of Tc-99m DISIDA cholescintigraphy as a predictor of eventual catheter and hepatic function in patients who have undergone percutaneous transhepatic biliary drainage (PTBD) for extrahepatic biliary obstruction was evaluated. Twenty-nine cholescintigrams were performed in 14 patients. The examinations were divided into two groups: Group A (N = 17), in which the patient's clinical status deteriorated within two to three days post-PTBD, and Group B (N = 12), in which the patients did well clinically post-PTBD. No significant difference between the two groups was demonstrated by visual analysis of the analog images or by analysis of serum bilirubin levels. A computer program, developed by the authors, quantitates several parameters of DISIDA kinetics, reflecting hepatic function based upon compartmental analysis. A significant difference (P less than .001) was demonstrated between the mean transport constants (blood clearance constant = k1; hepatic clearance constant = k2) for the two groups. It is concluded that serum bilirubin levels and visual inspection of analog images are inadequate independent predictors of hepatic function in patients post PTBD. The transport constants k1 and k2 are quantitative parameters of hepatic function that may be of prognostic value in patients post PTBD
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