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The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.2018-05-01T06:00:11ZOsmotic coefficients and Activity coefficients of Primitive Model electrolyte solutions in the Symmetric and Modified Poison-Boltzmann theories; A comparative study with Monte Carlo simulations.
http://hdl.handle.net/11721/1698
Osmotic coefficients and Activity coefficients of Primitive Model electrolyte solutions in the Symmetric and Modified Poison-Boltzmann theories; A comparative study with Monte Carlo simulations.
Quiñones Rivera, Adriel O.
Osmotic coefficients, individual and mean activity coefficients of primitive
model electrolyte solutions are computed at different molar concentrations using
the Symmetric Poisson Boltzmann and Modified Poisson Boltzmann theories. The
theoretical results are compared with an extensive series of Monte Carlo simulation
data obtained by Zareen Abbas, et al. (J. Phys. Chem. B, vol. 113, pp. 5905-5916
(2009)). This was achieved by adjusting the ion size parameters and the ion
valences in the theories to match the corresponding Monte Carlo data. The
agreement between Modified Poisson-Boltzmann predictions with the exact
simulation results is almost quantitative for monovalent salts, while being semiquantitative
or better for higher and multivalent salts. The Symmetric Poisson
Boltzmann results, on the other hand, are very good for monovalent systems but
tend to deviate for higher valency systems. Some recent experimental values for
activity coefficients of HCl solution (individual and mean activities) and NaCl
solution (mean activity only) have also been compared with the Symmetric and
Modified Poisson-Boltzmann theories, and with the Monte Carlo simulations. For
HCl, the theories and the simulations reproduce well the experimental results for
the mean activity coefficients but reproduce poorly the individual coefficients. For
the NaCl solution, the experimental mean activity coefficient matches well with the
theories and the simulations
2018-02-13T00:00:00ZAn analysis of the fluctuation potential in the modified Poisson-Boltzmann Theory for primitive model electrolytes
http://hdl.handle.net/11721/1696
An analysis of the fluctuation potential in the modified Poisson-Boltzmann Theory for primitive model electrolytes
Ulloa Dávila, Ernesto
The fluctuation potential problem in the modified Poisson-Boltzmann approach to charged fluids is analyzed to obtain an approximate analytic solution for a symmetric valency restricted primitive model electrolyte. The solution is valid for all ranges of interionic distances, including contact values. The structure of the electrolyte is described using radial distribution functions determined through the implementation of the fluctuation potential solution in the theory. Aspects of thermodynamics of the solution, viz., configurational reduced energies and osmotic coefficients are also calculated. Results have been obtained for symmetric valency 1:1 electrolyte system with the following physical parameters: ionic diameter d = 4.25×10-10 m, relative permittivity εr =78.5, absolute temperature T = 298 K, and molar concentrations c = 0.1038 M, 0.425 M, 1.00 M, and 1.968M. The ion-ion radial distribution functions are compared with the corresponding results from the symmetric Poisson-Boltzmann and the conventional modified Poisson- Boltzmann theories. Contact values of the radial distributions, reduced configurational energies, and osmotic coefficients have also been compared, as functions of electrolyte concentration, with these theories, and additionally with the Debye-Hückel theory and Monte Carlo simulation data from the literature. The results show very good agreement with the Monte Carlo data, and some improvement for radial distribution contact values and osmotic coefficients relative to these theories. The reduced energy curve shows excellent agreement with Monte Carlo data for molarities up to 1 mol/dm3. Radial distribution contact values for the charge asymmetric RPM 2:1 valency system at the same physical parameters of the 1:1 ,except for valence, case were also calculated and compared with the corresponding hypernetted chain theory from the literature. Good agreement was found for all concentrations considered. An ion size asymmetric primitive model extension to the theory is also presented. Osmotic coefficients are calculated and compared to simulation data from the literature for a primitive model electrolyte at the physical parameters: diameter of the large negative ion is 4.25×10-10m, the temperature T=298K, the dielectric constant of the electrolyte εr = 78.5, electrolyte concentration 0.425mol/dm3, and the size asymmetry parameter α = 0.4, 0.6, and 0.8. Good agreement between the results and the MC simulation was found.
2018-01-09T00:00:00ZStatistical causality structure on prostate cancer in Puerto Rico and USA
http://hdl.handle.net/11721/1695
Statistical causality structure on prostate cancer in Puerto Rico and USA
Alvarado Alvarado, Andrés G.
The purpose of this topic is to find specific statistical definitions to connect it to causal conditions. Also, use multiple data-sets of experiments to show how the statistics values are related to causality given the condition. I will use TETRAD Program to find possible causal models for the given data set.
2017-07-20T00:00:00ZEntre el recuerdo y el olvido: las memorias de los exiliados antitrujillistas
http://hdl.handle.net/11721/1694
Entre el recuerdo y el olvido: las memorias de los exiliados antitrujillistas
Bonilla-Carlo, Walter R.
En este artículo se analiza cómo el exilio construyó su lucha en contra de Trujillo desde la memoria y el olvido, a partir del poder evocativo y político presente en relatos autobiográficos. Un elemento importante al abordar este tipo de textos es visualizar, dependiendo de la situación política, cuáles son las estrategias discursivas que se utilizan para recordar u olvidar un acontecimiento en particular. Por tal motivo, se examina cómo en cada una de las memorias estudiadas están representadas y justificadas las luchas de poder entre las diferentes agrupaciones políticas fuera de la República Dominicana.
2003-01-01T00:00:00Z