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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 11 (1973), S. 0 
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: The movement of bacteria-laden waters percolating through fractured crystalline bedrock in mountainous terrain was examined to determine whether effluent originating from domestic waste disposal systems could contaminate shallow ground-water supplies. Inoculated waters were injected into holes and/or wells at two geologically different test sites (granitic, metamorphic) to evaluate the extent of microbial filtration in or along bedrock fractures. Microbiological examination of tracer waters, sampled both above and below the zone of saturation, was made.Field studies showed that the direction and rate of movement of contaminated ground waters were controlled largely by the anisotropic nature of the geologic stratum, particularly by the orientation of major bedrock fracture sets. Inoculated waters were found to be readily transported by the ground-water gradient into a downslope well. At one test site, a tracer bacterium traversed a horizontal distance of 94 feet in 24-30 hours. Continued bacteriological analysis of the contaminated well found the organism to be present for at least five days after inoculation of the upslope well.In the zone of aeration, bacteria-laden effluent was found to percolate in or along fractures with inadequate filtration prior to entering the ground water. Studies conducted in metamorphic rock demonstrated that while fecal-type bacteria decreased slightly during percolation through bedrock fractures, total bacterial densities were generally unchanged.From the hydrogeological and microbiological data obtained at both test sites, it can be concluded that moderate percolation rates and minimum distances between water wells and leachfield type waste disposal units are inadequate to protect potable ground-water supplies from contamination in mountainous terrain.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Bulletin of environmental contamination and toxicology 6 (1971), S. 129-132 
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Digestive diseases and sciences 17 (1972), S. 1055-1064 
    ISSN: 1573-2568
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A high incidence of gastric ulceration is reported in patients with rheumatoid arthritis and in addicts taking large doses of aspirin. In rheumatoid arthritis a serum salicylate level of 15 mg% is considered to be therapeutic. We studied gastric mucosal permeability to ions in 9 healthy subjects given 3 g aspirin intravenously over 2 hours (mean serum salicylate, 17 mg%). Atropine was injected intravenously to reduce acid secretion which masks H+ loss. H+ and Na+ fluxes during aspirin infusion were not significantly different from those during intravenous saline infusion. Thus, high blood levels of salicylates did not impair the gastric mucosal barrier. Intragastric salicylic acid following intravenous aspirin infusion increased gastric mucosal permeability to H+ and Na+ ions. Under the conditions of these studies the effect was more marked in males. Gastric absorption of salicylic acid was similar in males and females, and the amount absorbed was unaffected by the presence of high blood levels of salicylates. Absorption of salicylic acid was significantly greater in the first period of salicylic acid instillation (mean, 28%) than in the second (mean, 21%) and third (mean, 16%) periods. Percentage absorption of undissociated salicylic acid was at least three times greater than that of H+ ions.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 6 (1972), S. 347-374 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In this investigation, ceramics were studied to determine their role as rigid, abrasive implants in soft, living tissue. Discs and tubes of three ceramics, CaO·Al2O3, CaO·TiO2, and CaO·ZrO2, were introduced as porous and non-porous structures into muscle and connective tissue sites in rabbits. The animals were observed grossly to determine the duration of redness and swelling following surgery, and samples were retrieved at 1 week, 3 months, 6 months, and 9 months after implantation. A mild, acute inflammatory response immediately followed the implantation of all three materials in both the porous and non-porous forms. Histological sections of the ceramics and surrounding tissue, cut and stained for light microscopy, demonstrated the absence of inflammatory cells and revealed the normal morphology and organization of the cells present around all types of implants tested. Tissue around discs of porous ceramics healed faster and exhibited thinner fibrous encapsulations than with impervious discs of the same material. Healthy fibrous connective tissue with an ample blood supply occupied those implants with pores of 45-100 mμ, and even more rapidly filled the samples with a 100- to 150-μ pore size. The tissue ingrowth and tight adherence to the porous samples was believed responsible for the more moderate response to porous implants. No adverse responses of any kind were observed, except in a very few, atypical specimens.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 5 (1971), S. 269-279 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The trachea is a rather simple structure, and partly because of this simplicity, many attempts have been made to effect replacement with various types of prosthetic tubes. Unfortunately, the basic design of the trachea is not easily duplicated, and thus far there is no completely satisfactory prosthetic replacement. A series of porous and non-porous ceramics implanted in muscle tissue of rabbits indicated that rigid, porous materials can be compatible with soft, viable tissue. A prosthesis of porous ceramic rings and alternate bands of Dacron mesh was constructed and employed to bridge 6-cm defects created in the tracheas of mongrel dogs. After 6 months an asymptomatic animal was sacrificed. Firm fixation was accomplished and the lumen was completely patent, but histological sections demonstrated that ingrowth and scarring did not satisfactorily contain bacterial infection. Encouragement of epithelial regeneration or some artificial barrier is necessary for successful implants. Work in progress includes devices using both methods to provide this barrier.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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