Peng behavior

Peng, X., Bowser, M.T., Britz-McKibbin, P., Bebault, G.M., Morris, J.R., and Chen, D.D.Y., Quantitative description of analyte migration behavior based on dyamic complexation in capillary electrophoresis with one or more additives, Electrophoresis, 18, 706, 1997. 

Wang BE, Hu YY, Xie L, Peng K (2008) Biosorption behavior of azo dye by inactive CMC immobilized Aspergillus Jumigatus beads. Bioresour Technol 99 794—800... 

The need for methods of accurately describing the thermodynamic behavior of natural and synthetic gas systems has been well established. Of the numerous equations of state available, three--the Soave-Redlich-Kwong (SRK) (19), the Peng-Robinson (PR) (18) and the Starling version of the Benedict-Webb-Rubin (BWRS) (13, 20)--have satisfied this need for many hydrocarbon systems. These equations can be readily extended to describe the behavior of synthetic gas systems. At least two of the equations (SRK and PR) have been further extended to describe the thermodynamic properties of water-light hydrocarbon systems. 

In an earlier paper Q ), the authors presented an efficient procedure for predicting the phase behavior of systems exhibiting a water - rich liquid phase, a hydrocarbon - rich liquid phase, and a vapor phase. The Peng-Robinson equation of state (2) was used to reDresent the behavior of all three phases. It has the following form ... 

Although the bulk of PDA sensors involve vesicles and Langmuir monolayers, a few examples of responsive PDA assemblies based on bolaamphiphiles and diyne silica nanocomposites have been reported (Lu et al. 2001 Song et al. 2001, 2004 Yang et al. 2003 Peng et al. 2006). Although these materials have not been broadly utilized for analyte sensing, they do exhibit the thermochromic, solvatochro-mic, and pH responsive behavior seen with monolayers and liposomes and hold promise for future development. 

In small lab-scale STRs almost complete mixing of the gas-phase can also be assumed whereas plug-flow or mixed behavior can be generally assumed for the gas phase in bubble columns (Marinas et. al., 1993 Stockinger, 1995 Huang et al., 1998) and packed towers (Lin and Peng, 1997). 

As mentioned earlier, we have chosen to model the high-pressure phase behavior using the Peng-Robinson equation (Peng and Robinson, 1976) with standard van der Waals mixing rules ... 

For the epoxidation of /nmv-2-hexen-1-ol to (2R,3R)-( + )-3-propyloxirane-methanol, we have measured the high-pressure phase behavior of each of the reactants, products, and catalysts in C02 and modeled them quite well with the Peng-Robinson equation, even in the cases where we observed vapor/ liquid/liquid equilibria (Stradi et al., 1998). 

Figure 2. Phase equilibrium behavior for the binary system carbon dioxide - acetone. Experimental, 313 K (A) experimental, 333 K ( ) literature, 313 K (x) modified Peng-Robinson equation of state (—). Literature data are from reference (10).

A model based on a modified mixing rule for the Peng-Robinson equation of state was able to reproduce quantitatively all features of the observed phase equilibrium behavior, with model parameters determined from binary data only. The use of such models may substantially facilitate the task of process design and optimization for separations that utilize supercritical fluids. 

The carbon di oxi de/lemon oil P-x behavior shown in Figures 4, 5, and 6 is typical of binary carbon dioxide hydrocarbon systems, such as those containing heptane (Im and Kurata, VO, decane (Kulkarni et al., 1 2), or benzene (Gupta et al., 1 3). Our lemon oil samples contained in excess of 64 mole % limonene so we modeled our data as a reduced binary of limonene and carbon dioxide. The Peng-Robinson (6) equation was used, with critical temperatures, critical pressures, and acentric factors obtained from Daubert and Danner (J 4), and Reid et al. (J 5). For carbon dioxide, u> - 0.225 for limonene, u - 0.327, Tc = 656.4 K, Pc = 2.75 MPa. It was necessary to vary the interaction parameter with temperature in order to correlate the data satisfactorily. The values of d 1 2 are 0.1135 at 303 K, 0.1129 at 308 K, and 0.1013 at 313 K. Comparisons of calculated and experimental results are given in Figures 4, 5, and 6. 

Peng, J., Chen, S., Biisser, S., Liu, H., Honegger, T. and Kubli, E. (2005). Gradual release of sperm bound sex-peptide controls female postmating behavior in Drosophila. 

Figure 2.2 is a similar plot except for hydrogen sulfide. The predictions from the Peng-Robinson equation are compared with the NBS Tables (Goodwin, 1983). Note also the similar behavior in the prediction of the densities. 

Zhang L., Guo J., Peng X., and Jin, Y. (2004). Preparation and release behavior of earboxy-methylated chitosan/alginate mierospheres eneapsulating bovine serum albumin. J. Appl. Polym. Sci. 92, 878-882. 

In order to expand the scope of our experimental observations we have predicted the phase behavior for this ternary mixture over an extended range of temperatures and pressures using the Peng-Robinson e(quation of state (8). ... 

The full extent and variety of the phase behavior for water-isopropanol-C02 mixtures observed experimentally and calculated with the Peng-Robinson equation of state was not anticipated based on known phase behavior for the constituent binary mixtures or similar ternary mixtures. These results suggest that multiphase behavior for related model surfactant systems could also be complex. Measurements of all the critical endpoint curves, the tricritical points, and secondary critical endpoint for such systems would be tedious and are extremely difficult. However, by coupling limited experimental data with a thermodynamic model based on this cubic equation of state, complex multiphase behavior can be comprehensively described. 

Peng C X, Yang L, Zhang Z X, et al. Investigation of the anodic behavior of Al current collector in room temperature ionic liquid electrolytes. Electrochim. Acta. 2008. 53, 4764-4772. 

We also comment on certain speculations made by Peng et al. [25] regarding their analysis of the set of HRV time series speculations that have been supported by subsequent research. They suggested that the scaling behavior is adaptive for two reasons ... 

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