Tracer evaluation

Fenske, R.A. (1988). Visual Scoring System for Fluorescent Tracer Evaluation of Dermal Exposure to Pesticides, Bull. Environ. Contam. Toxicol, 41, 727-736. 

Fenske, R.A. (1993b). Fluorescent Tracer Evaluation of Protective Clothing Perfomuince. Final Report, US Environmental Protection Agency, Risk Reduction Engineering Laboratory, Office of Research and Development, Cincinnati, OH, USA. 

Many tracer chemicals are inherently unstable even as the unlabeled forms. Susceptibility of a chemical to hydrolysis, oxidation, photolysis, and microbiological degradation needs to be evaluated when designing suitable storage conditions for the labeled compound. Eactors that reduce radiolytic degradation, such as dispersal in solution, are apt to increase chemical degradation or instability. 

B. J. Ehrlich and S. E. Spencer, Development of an Automated Mustard S tack Monitor, Edgewood Arsenal Report No. ED-CR-76084, Tracer, Inc., June 1976. L. Schwart2 and co-workers. Evaluation of Ml 5/Ml 8 Enyme Detector Ticket System with Eow Concentration of GB, Edgewood Arsenal Report No. 

Tracer Diffusivity Tracer diffusivity, denoted by D g is related to both mutual and self-diffusivity. It is evaluated in the presence of a second component B, again using a tagged isotope of the first component. In the dilute range, tagging A merely provides a convenient method for indirect composition analysis. As concentration varies, tracer diffusivities approach mutual diffusivities at the dilute limit, and they approach selr-diffusivities at the pure component limit. That is, at the limit of dilute A in B, D g D°g and... 

Relatively uncomphcated transparent tank studies with tracer fluids or particles can give a similar feel for the overall flow pattern. It is important that a careful balance be made between the time and expense of calculating these flow patterns with computational flirid dynamics compared to their apphcabihty to an actual industrial process. The future of computational fluid dynamics appears very encouraging and a reasonable amount of time and effort put forth in this regard can yield immediate results as well as potential (or future process evaluation. 

Detailed Evaluation Detailed evaluation is performed by measuring the capture efficiency, either by using the actual contaminant or by using a tracer gas. (In principle, it is possible to use particles as tracers, but gases are usually used as tracers.) The most reliable evaluation is to use the process-generated contaminant, since there are always problems with a tracer, due to the difficulties of feeding the tracer to the source in the same way and in a similar amount as the generated contaminant. ... 

Research has been conducted to evaluate the effectiveness of several LVHV nozzle configurations for capturing tracer aerosols for simulated industrial operations.Studies have been conducted to evaluate dust capture for LVHV nozzles on hand-held tools, and have demonstrated over 90% collection efficiencies for operations such as grinding and sanding. 

Evaluation can be performed by measuring capture efficiency using real contaminants and applying the real process or by substituting with tracer materials. A simpler, but qualitative, method of evaluation is the visualization of the airflow. If the relationship between capture efficiency and airflow rate is known, a measurement of the airflow rate can be used for frequent evaluation. See Section 10.5. 

TTie ability of the ventilation system to protect the worker efficiently can readily be determined by personal samples. The PIMEX method (see Chapter 12) can be used to determine the worker s exposure during various work phases. The capture efficiency as well as the supply air fraction can be measured using tracer gas techniques. Simple evaluation is carried out visually with smoke tube or pellet tests. Daily system evaluation is recommended using airflow or static pressure measurements at appropriate parts of the system. The air velocities, turbulence intensities, air temperature, mean radiant temperature, and air humidity should also be measured to provide an assessment ol thermal comfort. 

European Standard EN 1093-4. Safety of machinery—Evaluation of the emission of airborne hazardous substances. Part 4 Capture efficiency of an exhaust system— Tracer method. 1996. 

Since in most situations the perturbation quantities (V and c() are not explicitly resolved, it is not possible to evaluate the turbulent flux term directly. Instead, it must be related to the distribution of averaged quantities - a process referred to as parameterization. A common assumption is to relate the turbulent flux vector to the gradient of the averaged tracer distribution, which is analogous with the molecular diffusion expression. Equation (35). 

Via a passive scalar method [6] where or, denotes the volume fraction of the i-th phase, while T, represents the diffusivity coefiBcient of the tracer in the i-th phase. The transient form of the scalar transport equation was utilized to track the pulse of tracer through the computational domain. The exit age distribution was evaluated from the normalized concentration curve obtained via measurements at the reactor outlet at 1 second intervals. This was subsequently used to determine the mean residence time, tm and Peclet number, Pe [7]. 

Defaye, K. and Garcia Fernandez, J.M., Protonic and thermal activation of sucrose an the oligosaccaride composition of caramel. Carbohydrate Res., 256, Cl, 1994. Ratsimba, V. et al.. Qualitative and qnantitative evaluation of mono- and disaccharides in D-fructose, D-glucose and sucrose caramels by gas-liquid chromatography-mass spectrometry di-D-fructose dianhydrides as tracers of caramel authenticity, J. Chro-matogr. A, 844, 283, 1999. 

To improve the evaluation of a water and gas pilot, tracers were injected in the gas phase at the beginning of the first two-gas injection periods. Per-fluoromethylcyclopentane and perfluoromethylcyclohexane were used. In laboratory studies, these compounds were shown to have a higher partitioning to the oil phase than did tritiated methane. This caused a minor retention of the tracer [518,1119],... 

When a tracer is considered, it is important to evaluate its performance with respect to these criteria, especially stability during exposure and storage/analysis. Normal practice involves conducting weathering tests where field collectors are treated with known amounts of the tracer and an assessment is made of weathering, extraction and storage stability under conditions pertaining to the intended use. The characteristics of the tracer allow it to be applied uniformly over the application area. Typically, application monitors are used to verify both the application rate and the uniformity of the application. 

In contrast to thermal ionization methods, where the tracer added must be of the same element as the analyte, tracers of different elemental composition but similar ionization efficiency can be utilized for inductively coupled plasma mass spectrometry (ICPMS) analysis. Hence, for ICPMS work, uranium can be added to thorium or radium samples as a way of correcting for instrumental mass bias (e g., Luo et al. 1997 Stirling et al. 2001 Pietruszka et al. 2002). The only drawback of this approach is that small inter-element (e g., U vs. Th) biases may be present during ionization or detection that need to be considered and evaluated (e.g., Pietruszka et al. 2002). 

Bollinger MS Moore WS (1993) Evaluation of salt marsh hydrology using radium as a tracer. Geochim Cosmochim Acta 57 2203-2212... 

In the first case, the minimum values for the economic yardsticks were evaluated assuming that a conservative 7300 bbl (= 8150 bbl -850 bbl 1160 m3 = 1295 m3 - 135 m3) of incremental oil had been produced by the end of the project. Maximum values for the economic data were calculated by assuming that 9000 bbl (= 8150 bbl + 850 bbl 1430 m3 = 1295 m3 + 135 m3) of incremental oil were produced by only 61.6 % of the TFSA which had been injected into Well TU-120 this assumption is based on the results of the tracer study which showed that as much as 38.4 % of the injected fluids flowed out of the pilot pattern. In the final case, the most probable values for the economic yardsticks were calculated assuming the 8150 bbl (1295 m3> of incremental oil were produced by 90 % of the TFSA. 

The simplest method of estimating Q)L from experimental tracer data is based on an evaluation of the slope of the F(t) curve at t =7. If we evaluate the derivative of equation 11.1.33 at this point,... 

Whitaker, J.E., fdaugland, R.P., Moore, P.L., Hewitt, P.C., Reese, M., and Haugland, R.P. (1991) Cascade blue derivatives Water soluble, reactive, blue emission dyes evaluated as fluorescent labels and tracers. 

Horowitz L, Walters S, Mauzerall D, Emmons L, Rasch P, Granier C, Tie X, Lamarque J, Schultz M, Tyndall G, Orlando J, Brasseur G (2003) A global simulation of tropospheric ozone and related tracers Description and evaluation of MOZART, version 2. Journal of Geophysical Research 108(D24), DOI 10.1029/2002JD002853... 

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