Chemical consistent experimental procedures

Polymer flow tests consisted of sequentially injecting 300-ppm polymer, 600-ppm polymer, and brine. Solutions were prepared and used in a manner that minimized chemical degradation. Each flood sequence was continued until both effluent polymer concentration and resistance factor stabilized. In some cases, polymer injection was terminated before fluid of injection concentration was produced. Details of the experimental procedure are included in Appendix A. The resistance factor at a given stage of the polymer flood was determined as the ratio of the flowing pressure drop at that stage to the initial brine pressure drop at the same rate. Figs. 1 and 2 exhibit the extremes of concentration response observed with these cores. Core 55 rapidly attained a produced concentration equal to the injected concentration, while Core 42 reached a maximum produced concentration of about 96 percent of injected. 

Consistent Data-Recording Procedures. Clear procedures for recording all pertinent data from the experiment must be developed and documented, and unambiguous data recording forms estabUshed. These should include provisions not only for recording the values of the measured responses and the desired experimental conditions, but also the conditions that resulted, if these differ from those plaimed. It is generally preferable to use the values of the actual conditions in the statistical analysis of the experimental results. For example, if a test was supposed to have been conducted at 150°C but was mn at 148.3°C, the actual temperature would be used in the analysis. In experimentation with industrial processes, process equiUbrium should be reached before the responses are measured. This is particularly important when complex chemical reactions are involved. 

Chemical vapor deposition (CVD) of carbon from propane is the main reaction in the fabrication of the C/C composites [1,2] and the C-SiC functionally graded material [3,4,5]. The carbon deposition rate from propane is high compared with those from other aliphatic hydrocarbons [4]. Propane is rapidly decomposed in the gas phase and various hydrocarbons are formed independently of the film growth in the CVD reactor. The propane concentration distribution is determined by the gas-phase kinetics. The gas-phase reaction model, in addition to the film growth reaction model, is required for the numerical simulation of the CVD reactor for designing and controlling purposes. Therefore, a compact gas-phase reaction model is preferred. The authors proposed the procedure to reduce an elementary reaction model consisting of hundreds of reactions to a compact model objectively [6]. In this study, the procedure is applied to propane pyrolysis for carbon CVD and a compact gas-phase reaction model is built by the proposed procedure and the kinetic parameters are determined from the experimental results. 

In one experiment the checkers used 3-butyn-l-ol available from Aldrich Chemical Company, Inc., and found that it was of satisfactory purity. In other experiments, both the submitters and the checkers prepared the hydroxy compound from sodium acetylide and ethylene oxide in liquid ammonia according to the procedure described by Schulte and Reiss3 and further attempted to maximize the yield by varying the ratio of sodium ethylene oxide liquid ammonia used ip the reaction. Unfortunately, the checkers failed to obtain consistent results in repeated experiments and consequently could not define the optimum conditions for the reaction. Thus, the yield of 3-butyn-l-ol varied from 15 to 45% and 15 to 31% on the basis of sodium and ethylene oxide, respectively. Unknown and apparently subtle experimental factors affect the yield significantly. 

To conclude, we see the recent update of the Nagra/PSI data base as a small, but important, step towards completeness and reliability of the large body of thermodynamic data needed to calculate chemical equilibrium in the complex geochemical systems occurring within or in the vicinity of radioactive waste disposal sites. The most important achievement in this exercise was probably the elimination of a conspicuous number of thermodynamic data not supported by experimental evidence or of dubious origin. This sieving procedure resulted in a reduced, but at least transparent and self-consistent data base. Future extensions can now be built on this well-documented basis. 

An alternative procedure to gain deeper insight into the physico-chemical basis of solvation consists of the partitioning of AGsoi into its enthalpic, A//soi, and en-tropic, A.S(o, components. Taken together, these quantities represent a substantial reservoir of information about the interactions between solute and solvent molecules. Moreover, these quantities are state functions and can be rigorously derived by using standard thermodynamic relationships, as noted in Eqs. 4-2 and 4-3. Finally, the availability of experimentally measured data for the enthalpy and entropy of solvation makes it possible to calibrate the reliability of theoretical models to predict those thermodynamic quantities. 

Some salient points to note are (i) the model is in accord with the experimental results, (ii) nuclei at a and yS positions to the coordinating atom show deviations from the model due to contributions of other shift mechanisms. Thus the best procedure for the elucidation of molecular structure by using lanthanide reagents consists of (i) to obtain the relative magnitude of geometrical function, G for different ligand nuclei from the slopes of A bT versus 1 / T plots, (ii) since temperature dependence of ytterbium complexes conforms to the model, use of ytterbium complexes is prudent, (iii) in cases where the temperature dependence is interfered with effects due to chemical equilibrium or exchange, data for a number of lanthanides at room temperature may be obtained and plots of equation... 

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