Contaminant, origin

These contaminates originate largely from the heavy (1,050-t- °F/ 566-t- °C), high-molecular weight fraction of the FCC feed. The quantity of these metals on the E-cat is determined by their levels in the feedstock and the catalyst addition rate. Essentially, all these metals in the feed are deposited on the catalyst. Most of the iron on the E-cat comes from metal scale from piping and from the fresh catalyst. 

Condensate contamination originates from several sources, including BW carryover into the generated steam, corrosion debris pickup... 

Analysis of biological samples requires an inline precolumn or guard column installed before the analytical column, to protect against the gradual accumulation of particulates or contaminants originating from the sample. They should be packed with a similar material as the analytical column and should be disposed of on the first indication of contamination (i.e., high back pressure or loss of resolution). 

If the surface temperature is not corrected for evaporative cooling, the evaporation rate is greatly overpredicted, as indicated by the difference between the experimental data points and the dotted lines of Fig. 32. When Eq. (103) is used to calculate the surface temperature, theory and experiment are in reasonably good agreement, although there is some evidence that the evaporation rate decreases near the end of the experiment. This is likely due to an increasing concentration of trace contaminants originally in the droplet. 

The adsorption of contaminants on geosorbents also is affected by climatic conditions reflected in the subsurface temperature and moisture status. Calvet (1984) showed how the soil moisture content may affect adsorption of contaminants originating from agricultural practices. The moisture content determines the accessibility of the adsorption sites, and water affects the surface properties of the adsorbent. The competition for adsorption sites between water and, say, insecticides may explain this behavior. Preferential adsorption of the more polar water molecules by soil hinders... 

Structure sensitivity of CH4 combustion over PdO is also a widely debated issue [67]. Ribeiro and co-workers [76, 87] carefully reviewed data reported in earlier studies and suggested that the wide scatter of turnover frequencies was mostly due to spurious factors such as neglect of H2O inhibition, the presence of contaminants originating either from Pd precursors (e.g. Cl [88]) or from the support (e.g. 

A complication in the study of biological materials is that the species of an element which are either formed and/or take part in physiological reactions in different compartments may vary. It is therefore necessary, especially during the sampling and pretreatment steps, that the constituents from different compartments are very carefully separated. For example, in the study of the speciation of an element in blood serum contaminants originating from the erythrocytes could lead to errors in the results. 

All ions can be identified as arising from the monomeric silane molecules. There is no evidence for peaks due to contaminants originally present at the substrate surface or in the silane solution. Further, there are no ions which contain more than three carbon atoms. 

The observation that imposex occurred primarily in marinas suggested causality with some contaminant originating from such facilities. Field experiments demonstrated that neogastropods transferred from pristine sites to marinas often developed imposex. Laboratory studies eventually implicated tributyltin, a biocide used in marine paints, as the cause of imposex. Tributyltin is toxic to most marine species evaluated in the... 

Enable us to determine whether ambient contamination or cross-contamination occurred during shipping and to detect contamination originating from sample containers and chemical preservatives. 

Most often, trip blank contamination originates in the laboratory, either from common airborne laboratory contaminants (methylene chloride, acetone) or from laboratory water containing VOCs, typically methylene chloride, acetone, and toluene or water disinfection byproducts (chloroform, dichlorobromomethane, chlorodibromomethane, bromoform). Rare, but well documented sources of trip blank and associated field samples contamination are insufficiently clean sample... 

Sporadic trace contamination originating from inadequate glassware washing at the laboratory also interferes with analysis. 

Sampling of materials, surfaces, and so on for micro-organisms can perturb the results not all contamination originates with the process. 

A first part of water contamination originates from dissolved organics. Let us assume a yield for AN separation of 98.5% with 1.5% losses in water. Sour water concerns the neutralization of ammonia with sulfuric acid. The lights and heavies are incinerated. Summing up, the following environmental costs should be included ... 

Tatalovich ME, Lee KY, Chrysikopoulos CV (2000) Modeling the transport of contaminants originating from the dissolution of DNAPL pools in aquifers in the presence of dissolved humic substances. Transp Porous Media 38 93-115... 

Another source of deactivation is Fe contamination originating from the corrosion of upstream equipment depositing on the gauze resulting in decomposition of the NH3 to N2. Another source is from the Fe-containing ammonia synthesis catalyst. 

Dynamic Mode in Non-Contact Regime In the non-contact mode, the cantilever is held within a 0.5 to a few nm distance of the surface and the cantilever is oscillated. Here, the tip only exerts a very low force on the sample (10 N up to 10 N). The large distance between tip and sample is advantageous for studying soft and elastic materials. Furthermore, the probability for contamination originating from the tip is reduced. 

Besides the nitrogen contamination due to pollution of the carrier gas, the diamond films obtained by chemical vapour deposition (CVD) are usually contaminated with silicon. This contamination originates from the plasma etching of the silica walls of the reactor and of the commonly used silicon substrates [37]. 

T.W.C. mainly consists of A1 (AI2O3) and Ce (Ce02) as support, Zr (Zr02 as promoter), Ba (BaO or BaS04 as stabilizer). Calcium and phosphorous detected in the aged catalyst are contaminants originating from the lubricants and the fuel. 

The appearance of surface activity and an apparent CMC could well be caused by low molecular weight contaminants, originating e.g. from insufficient removal of educts or as by-products of the synthesis, or from partial decomposition [143, 144, 213]. The strong effects of hydrophobic counterions bound to polyelectrolytes on the surface tension are well known [350] and traces many suffice to provoke the effect. Alternatively, apparent CMC s of polysoaps have been reported when low oligomers are involved [241, 242, 251, 353]. Thus dimers or trimers etc. might be responsible for the effect, exhibiting inter-molecular micellization (see Sect. 6). 

The bead surface critically affects nonspecific binding, which is particularly serious in the presence of physiological fluids, e.g., human whole blood. Conventional polymeric surfaces need chemical coupling processes to immobilize functional molecules and are vulnerable to contamination originating from nonspecific adsorption of proteins that are not analytes, like albumins in blood. Polymers including ethylene glycol oligomers have been tried in an effort to... 

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