Effects of experimental

By proper design of experiments, guided by a statistical approach, the effects of experimental variables may be found more efficiently than by the traditional approach of holding all variables constant but one and systematically investigating each variable in turn. Trends in data may be sought to track down nonrandom sources of error. 

It can be seen that k in Eq. (10) replaces the system-describing parameters L and Ah in Eq. (1). A direct test of the hypothesis is therefore to plot (j> against k for fixed values of P, G, and d, with L and Ah varying. For the hypothesis to be correct, the data points must all lie on a smooth curve. Experience shows, however, that plotting (f> against k often produces an undue amount of scatter which may obscure and distort any true relationship existing. This enhanced scatter is caused by the cumulative effect of experimental errors in the various terms in the heat-balance equation from which the quality k is derived. 

TABLE 10.3 Effects of Experimental Conditions on the Depolymerization Efficiency of Nylon-4,6... 

Used either as prelaboratory preparation for related laboratory activities or to expose students to additional laboratory activities not available in their program, these modules motivate students to learn by proposing real-life problems in a virtual environment. Students make decisions on experimental design, observe reactions, record data, interpret these data, perform calculations, and draw conclusions from their results. Following a summary of the module, students test their understanding by applying what they have learned to new situations or by analyzing the effect of experimental errors. 

Initial comparison of CFSTR runs with similar feed conditions indicates conditions for which the monomer conversion may be dependent on mixing speed. However, when the effects of experimental error in monomer conversion and differences in reaction temperature are considered, the monomer conversion is seen to be relatively independent of mixing speed for rpm equal to or greater than 500. Comparing Run 14 with Run 12 reveals a small decrease in monomer conversion in spite of a rise in reactor temperature of 2°C. This indicated the presence of a small amount of bypassing or dead volume at the lower mixing speed. This imperfect mixing pattern would also be present in Run 15. 

Table 5.3 Effect of experimental parameters on the LC-MS analysis of recombinant antibodies. Reprinted from J. Chromatogr., A, 913, Wan, H. Z., Kaneshiro, S., Frenz, J. and Cacia, J., Rapid method for monitoring galactosylation levels during recombinant antibody production by electrospray mass spectrometry with selective-ion monitoring , 437-466, Copyright (2001), with permission from Elsevier Science...

The fact that APCl and electrospray are soft ionization techniques is often advantageous because the molecular ion alone, in conjunction with HPLC separation, often provides adequate selectivity and sensitivity to allow an analytical method to be developed. Again, method development is important, particularly when more than one analyte is to be determined, when the effect of experimental parameters, such as pH, flow rate, etc., is not likely to be the same for each. Electrospray, in particular, is susceptible to matrix effects and the method of standard additions is often required to provide adequate accuracy and precision. 

Experimental design A number of formal procedures whereby the effect of experimental variables on the outcome of an experiment may be assessed. These may be used to assess the optimum conditions for an experiment and to maximize the accuracy and precision obtained. 

Plumb AP, Rowe RC, York P, Doherty C. The effect of experimental design in the modelling of a tablet coating formulation using artificial neural networks. Eur J Pharm Sci 2002 16 281-8. 

The longitudinal effects of experimental vitamin E deficiency on visual function in the rat have been studied by Goss-Sampson et al. (1992). After 12 months of deficiency, visual function as assessed by electroretinography was absent or grossly abnormal. This was associated with... 

Usually, one plots the initial rate V against the initial amount X, which produces a hyperbolic curve, such as shown in Fig. 39.17a. The rate and amount at time 0 are larger than those at any later time. Hence, the effect of experimental error and of possible deviation from the proposed model are minimal when the initial values are used. The Michaelis-Menten equation can be linearized by taking reciprocals on both sides of eq. (39.114) (Section 8.2.13), which leads to the so-called Lineweaver-Burk form ... 

Also, a chromatographic profile or fingerprint of trace unknowns can be established and monitored, so that if product performance unexpectedly changes, there will be a starting point for troubleshooting. The effects of experimental variables on sample recoveries should be measured directly by controlled variation of an experimental factor, using the reference standard, or suitable external standards, or spiked addition of an external standard to the reference standard. A detailed example of the use of internal and external standards is presented in Chapter 4. 

Effects of experimental parameters on pool boiling crisis with ordinary liquids In the... 

Effects of experimental parameters of pool boiling crisis with liquid metals... 

The target for optimization in FTA with CL detection is to adjust all experimental factors in such a way so that the detector views as much radiation as possible while the chemiluminescent solution flows through the cell. Hence the kinetics of the flow and detector system should be monitored to match the kinetics of the reaction and generate maximum intensity inside the cell. The effect of experimental variables on the CL signal cannot be exactly predicted in advance and there is not enough theoretical background to support any suggestion. 

Gamcik, P., J. Bires, L. Vrzgula, and P. Mesaros. 1990. Effect of experimental intoxication with copper from industrial emission on reproductive ability in rams. Reproduct. Domest. Anim. 25 235-241. 

Fantin, A.M.B., A. Franchini, E. Ottaviani, and L. Benedetti. 1985. Effect of pollution on some freshwater species. II. Bioaccumulation and toxic effects of experimental lead pollution on the ganglia in Viviparus ater (Mollusca, Gastropoda). Basic Appl. Histochem. 29 377-387. 

Verma, PC., R.P. Gupta, J.R. Sadana, and R.K.P. Gupta. 1988. Effect of experimental zinc deficiency and repletion on some immunological variables in guinea pigs. Brit. Jour. Nutr. 59 149-154. 

Houck, L.D., Bell, A.M., Reagan-Wallin, N.L. and Feldhoff, R.C. (1998) Effects of experimental delivery of male courtship pheromones on the timing of courtship in a terrestrial salamander, Plethodon jordani (Caudata Plethodontidae). Copeia 1998, 214-219. 

Lee KJ, Johnson N, Castelo J, Sinko PJ, Grass G, Holme K, Lee YH (2005) Effect of experimental pH on the in vitro permeability in intact rabbit intestines and Caco-2 monolayer. Eur J Pharm Sci 25 193-200. 

Overall, it appears that volunteers who received psychoactive agents did not suffer premature deaths. The matter of morbidity is less clear-cut. As with LTC McFarling s study, it was almost impossible to reach firm conclusions. No major category of illness was overrepresented in the experimental group. The panel noted that illnesses related to chromosomal or DNA damage, such as the leukemias, had actually occurred less often than expected in those who had received a dmg. Additional studies of the effects of experimental dmgs on DNA material were also negative or inconclusive. 

Consideration of the effect of experimental design on the elements of the variance-covariance matrix leads naturally to the area of optimal design [Box, Hunter, and Hunter (1978), Evans (1979), and Wolters and Kateman (1990)]. Let us suppose that our purpose in carrying out two experiments is to obtain good estimates of the intercept and slope for the model yj, = Po + Pi i, + r,. We might want to know what levels of the factor x , we should use to obtain the most precise estimates of po and... 

One purpose of a good design is to minimize uncertainty and maximize information over the region of interest. We will use both normalized uncertainty and normalized information to discuss the effect of experimental design on the quality of information obtained from a two-factor FSOP model. 

Uehlinger U, Kawecka B, Robinson CT (2003) Effects of experimental floods on periphyton and stream metabolism below a high dam in the Swiss Alps (River Spol). Aquat Sci 65 199... 

Ortlepp J, Miirle U (2003) Effects of experimental flooding on brown trout (Salmo trutta fario L.) The River Spol, Swiss National Park. Aquat Sci 65 232... 

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