Artificial contamination

Effieieney The ability, expressed as a percent, of a filter to remove specified artificial contaminant at a given contaminant concentration under specified test conditions. 

Tab. 5.1 Certified number concentration of colony forming particles of Enterococcus faecium (WR63) in CRM 506 from artificially contaminated milk powder (Mooijman et al. 1999)...

Malik, Y. S., Allwood, P. B., Hedberg, C. W., and Goyal, S. M. (2006a). Disinfection of fabrics and carpets artificially contaminated with calicivirus Elevance in institutional and healthcare centres. /. Hasp. Infect. 63,205-210. 

Ueki, Y., Shoji, M., Suto, A., Tanabe, T., Okimura, Y., Kikuchi, Y., Saito, N., Sano, D., and Omura, T. (2007). Persistence of caliciviruses in artificially contaminated oysters during depuration. Appl. Environ. Microbiol. 73, 5698-5701. 

No aflatoxin B1 was detected in a large number of green coffee samples. In order to evaluate aflatoxin B1 in coffee, green coffee beans were artificially contaminated. The aflatoxin B1 in these artificially contaminated green coffee beans was mostly decomposed by roasting and was further decomposed during coffee brew preparation.207... 

Micco, C., Miraglia, M., Brera, C., Desiderio, C., Masci, V., The effect of roasting on the fate of aflatoxin B1 in artificially contaminated green coffee beans, Myc-otoxin Res., 8(2), 93, 1992. (CA118 146443y)... 

Hunter, J.V., Origin of organics from artificial contamination, in Organic Compounds in Aquatic Environments, Faust, S.D. and Hunter, J.V., Eds., Marcel Dekker, New York, 1971, pp. 51-94. 

The lack of detection of LAS metabolites in sediments was also discussed by Sarrazin et al. [13] determining the biodegradability of the anionic surfactant in artificially contaminated sediments from a shallow pond. During the experiments, no LAS metabolites were observed. This was explained by the high solubility of these compounds, which may be quickly eliminated from the sedimentary layer by dissolution and diffusion into the pond water. 

During a more controlled study carried out within an environment artificially contaminated with high levels of individual nebulized spores of Bacillus subtilis [2], a level of contamination within the environment was achieved which led to the contamination of broth-filled units. The results were extrapolated to suggest a contamination rate of 1 unit in 4 X 10 with a smrounding environmental contamination of 1 cfu/ml... 

Hilarides and others (1994) investigated the destruction of TCDD on artificially contaminated soils using °Co y radiation. It appeared that TCDD underwent stepwise reduction dechlorination from tetra- to tri-, then di- to chlorodioxin, and then to presumably nonchlorinated dioxins and phenols. The investigators discovered that the greatest amount of TCDD destruction (92%) occurred when soils were amended with 25% water and 2% nonionic surfactant [alkoxylated fatty alcohol (Plurafac RA-40)]. Replicate experiments conducted without the surfactant lowered the rate of TCDD destruction. 

An application well-suited for IMS is the decommissioning and cleanup of sites where extensive manufacturing of explosives has taken place in the last century and where widespread contamination of soils and waters has occurred [74]. Decontamination of model metal scrap artificially contaminated with TNT and of decommissioned mortar rounds stiU containing explosives residue was followed by sampling surfaces with analysis by a portable mobility spectrometer. Mixed anaerobic microbial populations of bioslurries were employed in decontamination of scrap and the mortar rounds, and the IMS analyzer was seen as a sensitive field... 

Multi-element trace analysis is an important prerequisite for the quality assurance of foodstuffs with respect to the characterization of non-essential, toxic and essential (nutrient) elements as pollutions or as mineral elements relevant to health. Contamination with heavy metals such as Cd, Pb or Hg has become a serious problem with increasing environmental (artificial) contamination e.g., due to industrial pollution. The increasing use of inorganic mass spectrometric techniques (especially of ICP-MS) in the analysis of foodstuffs for multi-element analysis of trace elements or the detection of selected elements and species at a low concentration level has resulted from advances in very sensitive and quantitative measurements of metals, metalloids and several non-metals, including their speciation. 

In old contaminated soil sites, CPs are less accessible to biodegradation than CPs in more recently contaminated sites (Salkinoja-Salonen et al., 1989) inaccessibility correlates with unavailability of CPs to extraction by nonpolar solvents (diethyl ether, hexane). Remediation studies with artificially contaminated soil are likely to give lower residual CP concentrations than obtained in actual remediation. Decreased CP concentrations due to analytical limitations should not be interpreted as biodegradation. 

Polycrystalline Ni-Sb alloys, unsupported Sb-loaded Ni powders, artificially contaminated as well as equilibrium FCC (from a heavy oil cracker) have been studied using X-ray diffraction (XRD), Auger spectroscopy and x-ray photoelectron spectroscopy (XPS) by workers at Phillips in what was one of the first examples of a multi-characterization technique approach to FCC study (39,40). XPS results have indicated that in an equilibrium FCC, 50 to 80% of the surface Sb and 30% to 50% of the surface Ni could be reduced to metal. This XPS data suggested that Ni and Sb were present on at least two different sites (that can be differentiated by their reducibility at 500°C/H2) and that reduction caused a twofold increase in the Ni/Sb ratio due to greater Ni dispersion. 

At the higher metal level (2.0-4.5% Ni with up to 2% Sb) used to study artificially contaminated materials, XRD results have shown the formation of Ni-Sb alloys (NiSb x<0.08) whereas XPS data have indicated that a non-reducible antimony oxide, a well dispersed reducible Sb phase together with reducible Sb (that form an alloy with reducible Ni), were present. Selective chemisorption data for unsupported Ni-powders showed that one surface structure can effectively passivate 2-3 Ni atoms with respect to H2 chemisorption. XPS examination confirmed that Sb segregates at the surface of Ni particles where it can drastically affect the electron properties of neighboring Ni atoms thus reducing their activity. 

Hilardes RJ, Gray KA, Guzzetta J, et al. 1994. Radiolytic degradation of 2,3,7,8,-TCDD in artificially contaminated soils. Environ Sci Techol 28(13) 2249-2258. 

Another illustration of the potential in harnessing plant life for soil remediation is the finding20 that the fern, Pier is vittata, when grown in soil containing 6 ppm arsenic, hyper-accumulated 755 ppm of this metalloid in its fronds in only two weeks. When Pier is vittata was grown in artificially contaminated soil (1500 ppm As), the fronds took in 15,861 ppm As in the same two-week time frame. Similarly, research in both the United States and the United Kingdom has demonstrated the potential of using plants from the family Brassicacae in the remediation of soils heavily contaminated with zinc, cadmium, nickel, lead, and selenium.21... 

Rew and R ratios were used in conjunction with the truncated safety zone ratio, Rj z, to describe the results obtained with populations of known drug users. The percentage distributions of values for these wash kinetic parameters are given in Tables 2, 3, and 4. Based on the data from these populations of known drug users and the wash kinetic values obtained with artificially contaminated hair, the following cutoff levels were set for the truncated wash procedure R< = 1.3, Rew = 10/ Rtsz = 0.33. Samples are judged to be contaminated if any one of the three wash kinetic parameters falls below its cutoff value. 

Mare basalts indicate that the Moon s pattern of crust-mantle siderophile element depletions is roughly similar to that of the Earth (Figure 7). Unfortunately, for four siderophile elements, rubidium, rhodium, palladium, and platinum, no reliable data have been reported for lunar basalts. Neal et al. (1999, 2001) reported ICP-MS data, but their analyses show obvious artificial contamination, based on comparison with iridium data and palladium upper limits reported by Wolf et al. (1979). The most noble of the siderophile elements in Figure 7 are osmium and iridium. For noble siderophile elements, scatter among individual rocks is very great (e.g.. Figure 8), but the factor-of-4 disparity between average mare and terrestrial basalt for osmium and iridium... 

Smit, C.E. and Van Gestel, C.A.M. (1996) Comparison of the toxicity of zinc for the springtail Folsomia Candida in artificially contaminated and polluted field soils. Applied Soil Ecology, 3, 127-136. 

Bicarbonate ion is usually the chief anion in freshwaters. In and on silicate rocks, the HCOj concentration is usually 50 to 200 mg/L, whereas in groundwaters that contact a few percent carbonate materials up to pure limestone and dolomite, bicarbonate levels are usually in the range of 200 to 400 ppm. Seawater contains 140 mg/L HCOj. Carbonate alkalinity (CO3 ) rarely exceeds 10 mg/L. Why The presence of caustic alkalinity (free OH ) at pH s above 10 usually indicates artificial contamination of a water by, for example, Ca(OH)2 (portlandite) from the setting of concrete at newly completed wells. Cg concentrations can reach 1000 ppm as HCO3 in sodium carbonate-bicarbonate brines found in evaporative, closed basin lakes. 

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