Capacity factor response surface

Alternatively, the response surface may be calculated indirectly by describing the capacity factor (or retention time) as a function of the considered parameters, using the... 

For chromatographic separations it is more sensible to compare k values, because retention surfaces are easier to characterize than response surfaces. Hence, Jf in eqn.(5.2) is the capacity factor of the solute at the jth data point. Each solute will have its own values for and hence a different mean effect can be defined for each sample component and each parameter. The results for the four solutes and four parameters studied are given in table 5.2b. 

Chen, M.J., and Lin C.W. (2002). Factors affecting the water-holding capacity of fibrinogen/ plasma protein gels optimized by response surface methodology. J. Food Sci. 67, 2579-2582. 

Introduction of a hydrophobic comonomer, bntyl methacrylate, in the polymer resulted in a decreased transition temperatm-e of ahont 20°C. Retention of steroids in poly(NIPAAM-co-butyl methacrylate)-grafted colnnms increases as colmnn temperature increases. The capacity factors for steroids on the copolymer-modified silica beads was much larger than that on poly(NIPAAM)-grafted columns. The effect of temperature on steroid retention on poly(NIPAAM-co-hntyl methacrylate)-grafted stationary phases was more pronoimced compared to snpports modified with poly(NIPAAM). Furthermore, retention times for steroids increased remarkably as the butyl methacrylate content increased in the copolymer. The temperature-responsive elntion of steroids was strongly affected hy the hydropho-bicity of the grafted polsrmer chains on silica surfaces (63). 

Another issue with platinum catalysts is that their capacity sometimes fades over time. Several factors are responsible, including a phenomenon similar to the side effects described for medications in chapter 3. Side effects occur when a medication acts on healthy tissue instead of the intended target. With platinum electrodes, the problem is that sometimes unwanted reactions occur at the electrodes. In the oxygen reactions taking place at the cathode, for example, hydroxide (OH) and other molecules sometimes form and bind to the platinum atoms. These molecules cover the platinum atoms and block access to the desired reactant, thereby reducing the catalytic activity. Sometimes the molecules even pull platinum atoms away from the surface, causing serious electrode degradation. 

A study has been carried out on the interactions of blood with plasticised poly(vinyl chloride) biomaterials in a tubular form. The influence of different factors such as the biomaterial, antithrombotic agent, blood condition and the nature of the application is represented when considering the blood response in the clinical utilisation of the plasticised PVC. The PVC was plasticised with di-(2-ethylhexyl)phthalate (DEHP) and tri-(2-ethylhexyl)trimellitate (TEHTM)and in-vitro and ex-vivo procedures used to study the biomaterial with respect to the selection of the plasticiser. The blood response was measured in terms of the measurement of fibrinogen adsorption capacity, thrombin-antithrombin III complex and the complement component C3a. X-ray photoelectron spectroscopy was used for surface characterisation of the polymers and the data obtained indicated that in comparison with DEHP-PVC, there is a higher reactivity... 

Van Hal et al. [48] used the 2-pK and MUSIC models combined with diffuse layer and Stern electrostatic models (with pre-assumed site-density and surface acidity constants) to calculate the surface potential, the intrinsic buffer capacity -(d(To/dpHs)/e where pHs is the pH at the surface, the sensitivity factor -(d o/dpH) x [e/(kTln 10)], which equals unity for Nernstian response, and the differential capacitance for three ionic strengths as a function of pH. The calculated surface potentials were compared with the experimentally measured ISFET response. 

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