Secondary contamination and

Membranes are semipermeable barriers that permit the separation of two compartments of different composition or even condition, with the transport of components from one compartment to another being controlled by the membrane barrier. Ideally, this barrier is designed to let pass selectively only certain target compounds, while retaining all others—hence the denotation semipermeable . Membrane separations are particularly suitable for food applications because (1) they do not require any extraction aids such as solvents, which avoids secondary contamination and, hence, the necessity for subsequent purification (2) transfer of components from one matrix to another is possible without direct contact and the risk of cross-contamination (3) membrane processes can, in general, be operated under smooth conditions and therefore maintaining in principle the properties and quality of delicate foodstuff. 

A. Emergency and supportive measures. Caution Rescuers and health care providers must take measures to prevent direct contact with the skin or clothing of contaminated victims, because secondary contamination and serious illness may result, especially with potent pesticides and nerve agents (see Section IV, p 514.)... 

Examples of substances with significant potentiai for secondary contamination and requiring aggressive decontamination and protection of downstream personnel include potent organophosphoms insecticides, oily nitro compounds, and highly radioactive compounds such as cesium or plutonium. 

When producing composite samples care should be taken to measure the water and to ensure that secondary contamination, and influences from increases in temperature or from atmospheric oxygen, are as far as possible excluded or taken into consideration in evaluation. 

This was demonstrated clearly in a civil setting in the emergency room of St. Luke s Hospital, Tokyo, in 1995 after the terrorist subway sarin attack where staff were affected by low-level secondary contamination and had miosis and visual dysfunction which interfered with their ability to work. 

The U.S. Environmental Protection Agency, under the Safe Drinking Water Act, set the secondary contaminant level for silver ia drinking water at 0.1 mg/L (20). Secondary contaminants are not considered to be hazardous to health and thus the limits are not federally enforceable. 

A SSIMS spectrum, like any other mass spectrum, consists of a series of peaks of dif ferent intensity (i. e. ion current) occurring at certain mass numbers. The masses can be allocated on the basis of atomic or molecular mass-to-charge ratio. Many of the more prominent secondary ions from metal and semiconductor surfaces are singly charged atomic ions, which makes allocation of mass numbers slightly easier. Masses can be identified as arising either from the substrate material itself from deliberately introduced molecular or other species on the surface, or from contaminations and impurities on the surface. Complications in allocation often arise from isotopic effects. Although some elements have only one principal isotope, for many others the natural isotopic abundance can make identification difficult. 

The limitations of SIMS - some inherent in secondary ion formation, some because of the physics of ion beams, and some because of the nature of sputtering - have been mentioned in Sect. 3.1. Sputtering produces predominantly neutral atoms for most of the elements in the periodic table the typical secondary ion yield is between 10 and 10 . This leads to a serious sensitivity limitation when extremely small volumes must be probed, or when high lateral and depth resolution analyses are needed. Another problem arises because the secondary ion yield can vary by many orders of magnitude as a function of surface contamination and matrix composition this hampers quantification. Quantification can also be hampered by interferences from molecules, molecular fragments, and isotopes of other elements with the same mass as the analyte. Very high mass-resolution can reject such interferences but only at the expense of detection sensitivity. 

The analytical procedure is checked by analyses of method blanlcs to assure that secondary contamination by the analytes to be determined is avoided or minimized. Because the water content of the CRM matrix to be analyzed may vary from one laboratory to another (dependent on the local humidity and temperature), the water content has to be determined. Accordingly, at least three independent samples are kept at I05°C for 2 h, then allowed to cool to ambient temperature in a desiccator and the water loss is determined. The certified values are generally reported on a dry mass basis. 

Cl and Ba consistently argue that the U-series disequilibria in MORB do not reflect secondary contamination. One important check that all U-series studies of MORB routinely perform is analysis of ( " U)/( U). Since of seawater is well... 

Table 1 indicates primary pollutant sources and waste modes, and Table 2 indicates the primary and secondary sources and associated pollutants. The primary sources of soil contamination include land disposal of solid waste sludge and waste-water industrial activities and leakages and spills, primarily of petroleum products. The solid waste disposal sites include dumps, landfills, sanitary landfills, and secured landfills. 

About one third of the overall production was applied in buildings used as additives to dyes and joint sealers. Normally, the use of PCBs in the materials is not (more) known to the inhabitants or users of the houses. Only in the case of secondary contamination of ambient air or food detected by chance or by systematic search, those buildings were decontaminated. Spreading of PCBs into the environment was accelerated by mixing of used hydraulic or heat exchanger fluids... 

Intraabdominal infections have a wide spectrum of clinical features often depending on the specific disease process, the location and the magnitude of bacterial contamination, and concurrent host factors. Patients with primary and secondary peritonitis present quite differently (Table 42-3). 

Interaction of POCs with oil products and synthetic surfactants in water <- Factors increasing the ecological risk of contamination of river waters entering into the Caspian Sea by POCs Secondary contamination of river waters by POCs from bottom sediments... 

In the Rybinsk reservoir constructed in the upper Volga (Yaroslavl, Vologda and Tver regions), the ratio of PCBs in water and silts, in some places, was less than 1, which would suggest probable secondary contamination of water (Figure 7, Table 4)... 

Rates of POCs secondary contamination of fresh and salt waters from bottom sediments ... 

Regarding isolation and decontamination, Standard Precautions are recommended for healthcare personnel. Person-to-person transmission is rare. Victims exposed to Q fever by aerosol do not present a risk for secondary contamination or re-aerosolization of the organism. Decontamination can be done with soap and water, or a 0.5 percent chlorine solution on personnel. 

Hospital staff working in an enclosed area can be secondarily contaminated by cyanide vapor off-gassing from heavily soaked clothing or skin, or from toxic vomit. Avoid dermal contact with cyanide-contaminated victims or with gastric contents of persons who may have ingested cyanide-containing materials (patients do not usually pose secondary contamination risks after contaminated clothing is removed and the skin is washed. 

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