Search

Your search keyword '"Aguilella, V."' showing total 102 results
Start Over Author "Aguilella, V."
102 results on '"Aguilella, V."'

1. Prediction of peritoneal soiling in acute appendicitis with simple clinical and laboratory data. Prospective, multicenter, cohort study of 2,645 adult patients nationwide

Author

Afonso, N., Aguilella, V., Aguiló, J., Alados, J.C., Alberich, M., Apio, A.B., Balongo, R., Bra, E., Bravo-Gutiérrez, A., Briceño, F.J., Cabañas, J., Cánovas, G., Caravaca, I., Carbonell, S., Carrera-Dacosta, E., Castro E, E., Caula, C., Choolani-Bhojwani, E., Codina, A., Corral, S., Cuenca, C., Curbelo, Y., Delgado-Morales, M.M., Delgado-Plasencia, L., Doménech, E., Estévez, A.M., Feria, A.M., Gascón-Domínguez, M.A., Gianchandani, R., González, C., González, M.A., Hevia, R.J., Hidalgo, J.M., Lainez, M., López, F., López-Fernández, J., López-Ruíz, J.A., Lora-Cumplido, P., Madrazo, Z., Marchena, J., Marenco de la Cuadra, B., Martín, S., Martínez Casas, I., Martínez, P., Mena-Mateos, A., Morales-García, D., Mulas, C., Muñoz-Forner, E., Naranjo, A., Navarro-Sánchez, A., Oliver, I., Ortega, I., Ortega-Higueruelo, R., Ortega-Ruiz, S., Osorio, J., Padín, M.H., Pamies, J.J., Paredes, M., Pareja-Ciuró, F., Pérez-Guarinós, C.V., Pérez-Saborido, B., Pintor-Tortolero, J., Plua-Muñiz, K., Rey, M., Rodríguez, I., Ruiz, C., Ruíz, R., Ruiz, S., Sánchez, A., Sánchez, D., Sánchez, R., Sánchez-Cabezudo, F., Sánchez-Santos, R., Santos, J., Serrano-Paz, M.P., Soria-Aledo, V., Taccogna, L., Tallón-Aguilar, L., Valdivia-Risco, J.H., Vallverdú-Cartié, H., Varela, C., Villar-del-Moral, J., Zambudio, N., Lluís, N., Parra, J., Villodre, C., Zapater, P., Jalali, A., Cantó, M., Mena, L., Ramia, J.M., and Lluís, F.

Published
2022
Full Text
View/download PDF

2. Simplified risk-prediction for benchmarking and quality improvement in emergency general surgery. Prospective, multicenter, observational cohort study

Author

Afonso, N., Aguilella, V., Aguiló, J., Alados, J.C., Alberich, M., Apio, A.B., Balongo, R., Bra, E., Bravo-Gutiérrez, A., Briceño, F.J., Cabañas, J., Cánovas, G., Caravaca, I., Carbonell, S., Carrera-Dacosta, E., Castro E, E., Caula, C., Choolani-Bhojwani, E., Codina, A., Corral, S., Cuenca, C., Curbelo-Peña, Y., Delgado-Morales, M.M., Delgado-Plasencia, L., Doménech, E., Estévez, A.M., Feria, A.M., Gascón-Domínguez, M.A., Gianchandani, R., González, C., Hevia, R.J., González, M.A., Hidalgo, J.M., Lainez, M., Lluís, N., López, F., López-Fernández, J., López-Ruíz, J.A., Lora-Cumplido, P., Madrazo, Z., Marchena, J., Marenco de la Cuadra, B., Martín, S., Casas, I. Martínez, Martínez, P., Mena-Mateos, A., Morales-García, D., Mulas, C., Muñoz-Forner, E., Naranjo, A., Navarro-Sánchez, A., Oliver, I., Ortega, I., Ortega-Higueruelo, R., Ortega-Ruiz, S., Osorio, J., Padín, M.H., Pamies, J.J., Paredes, M., Pareja-Ciuró, F., Parra, J., Pérez-Guarinós, C.V., Pérez-Saborido, B., Pintor-Tortolero, J., Plua-Muñiz, K., Rey, M., Rodríguez, I., Ruiz, C., Ruíz, R., Ruiz, S., Sánchez, A., Sánchez, D., Sánchez, R., Sánchez-Cabezudo, F., Sánchez-Santos, R., Santos, J., Serrano-Paz, M.P., Soria-Aledo, V., Tallón-Aguilar, L., Valdivia-Risco, J.H., Vallverdú-Cartié, H., Varela, C., Villar-del-Moral, J., Zambudio, N., Villodre, C., Taccogna, L., Zapater, P., Cantó, M., Mena, L., Ramia, J.M., and Lluís, F.

Published
2022
Full Text
View/download PDF

3. Prediction of peritoneal soiling in acute appendicitis with simple clinical and laboratory data. Prospective, multicenter, cohort study of 2,645 adult patients nationwide

Author

Lluís, N., primary, Parra, J., additional, Villodre, C., additional, Zapater, P., additional, Jalali, A., additional, Cantó, M., additional, Mena, L., additional, Ramia, J.M., additional, Lluís, F., additional, Afonso, N., additional, Aguilella, V., additional, Aguiló, J., additional, Alados, J.C., additional, Alberich, M., additional, Apio, A.B., additional, Balongo, R., additional, Bra, E., additional, Bravo-Gutiérrez, A., additional, Briceño, F.J., additional, Cabañas, J., additional, Cánovas, G., additional, Caravaca, I., additional, Carbonell, S., additional, Carrera-Dacosta, E., additional, Castro E, E., additional, Caula, C., additional, Choolani-Bhojwani, E., additional, Codina, A., additional, Corral, S., additional, Cuenca, C., additional, Curbelo, Y., additional, Delgado-Morales, M.M., additional, Delgado-Plasencia, L., additional, Doménech, E., additional, Estévez, A.M., additional, Feria, A.M., additional, Gascón-Domínguez, M.A., additional, Gianchandani, R., additional, González, C., additional, González, M.A., additional, Hevia, R.J., additional, Hidalgo, J.M., additional, Lainez, M., additional, López, F., additional, López-Fernández, J., additional, López-Ruíz, J.A., additional, Lora-Cumplido, P., additional, Madrazo, Z., additional, Marchena, J., additional, Marenco de la Cuadra, B., additional, Martín, S., additional, Martínez Casas, I., additional, Martínez, P., additional, Mena-Mateos, A., additional, Morales-García, D., additional, Mulas, C., additional, Muñoz-Forner, E., additional, Naranjo, A., additional, Navarro-Sánchez, A., additional, Oliver, I., additional, Ortega, I., additional, Ortega-Higueruelo, R., additional, Ortega-Ruiz, S., additional, Osorio, J., additional, Padín, M.H., additional, Pamies, J.J., additional, Paredes, M., additional, Pareja-Ciuró, F., additional, Pérez-Guarinós, C.V., additional, Pérez-Saborido, B., additional, Pintor-Tortolero, J., additional, Plua-Muñiz, K., additional, Rey, M., additional, Rodríguez, I., additional, Ruiz, C., additional, Ruíz, R., additional, Ruiz, S., additional, Sánchez, A., additional, Sánchez, D., additional, Sánchez, R., additional, Sánchez-Cabezudo, F., additional, Sánchez-Santos, R., additional, Santos, J., additional, Serrano-Paz, M.P., additional, Soria-Aledo, V., additional, Taccogna, L., additional, Tallón-Aguilar, L., additional, Valdivia-Risco, J.H., additional, Vallverdú-Cartié, H., additional, Varela, C., additional, Villar-del-Moral, J., additional, and Zambudio, N., additional

Published
2022
Full Text
View/download PDF

4. Simplified risk-prediction for benchmarking and quality improvement in emergency general surgery. Prospective, multicenter, observational cohort study

Author

Villodre, C., primary, Taccogna, L., additional, Zapater, P., additional, Cantó, M., additional, Mena, L., additional, Ramia, J.M., additional, Lluís, F., additional, Afonso, N., additional, Aguilella, V., additional, Aguiló, J., additional, Alados, J.C., additional, Alberich, M., additional, Apio, A.B., additional, Balongo, R., additional, Bra, E., additional, Bravo-Gutiérrez, A., additional, Briceño, F.J., additional, Cabañas, J., additional, Cánovas, G., additional, Caravaca, I., additional, Carbonell, S., additional, Carrera-Dacosta, E., additional, Castro E, E., additional, Caula, C., additional, Choolani-Bhojwani, E., additional, Codina, A., additional, Corral, S., additional, Cuenca, C., additional, Curbelo-Peña, Y., additional, Delgado-Morales, M.M., additional, Delgado-Plasencia, L., additional, Doménech, E., additional, Estévez, A.M., additional, Feria, A.M., additional, Gascón-Domínguez, M.A., additional, Gianchandani, R., additional, González, C., additional, Hevia, R.J., additional, González, M.A., additional, Hidalgo, J.M., additional, Lainez, M., additional, Lluís, N., additional, López, F., additional, López-Fernández, J., additional, López-Ruíz, J.A., additional, Lora-Cumplido, P., additional, Madrazo, Z., additional, Marchena, J., additional, Marenco de la Cuadra, B., additional, Martín, S., additional, Casas, I. Martínez, additional, Martínez, P., additional, Mena-Mateos, A., additional, Morales-García, D., additional, Mulas, C., additional, Muñoz-Forner, E., additional, Naranjo, A., additional, Navarro-Sánchez, A., additional, Oliver, I., additional, Ortega, I., additional, Ortega-Higueruelo, R., additional, Ortega-Ruiz, S., additional, Osorio, J., additional, Padín, M.H., additional, Pamies, J.J., additional, Paredes, M., additional, Pareja-Ciuró, F., additional, Parra, J., additional, Pérez-Guarinós, C.V., additional, Pérez-Saborido, B., additional, Pintor-Tortolero, J., additional, Plua-Muñiz, K., additional, Rey, M., additional, Rodríguez, I., additional, Ruiz, C., additional, Ruíz, R., additional, Ruiz, S., additional, Sánchez, A., additional, Sánchez, D., additional, Sánchez, R., additional, Sánchez-Cabezudo, F., additional, Sánchez-Santos, R., additional, Santos, J., additional, Serrano-Paz, M.P., additional, Soria-Aledo, V., additional, Tallón-Aguilar, L., additional, Valdivia-Risco, J.H., additional, Vallverdú-Cartié, H., additional, Varela, C., additional, Villar-del-Moral, J., additional, and Zambudio, N., additional

Published
2022
Full Text
View/download PDF

18. Molecular Characterization of the Viroporin Function of Foot-and-Mouth Disease Virus Nonstructural Protein 2B

Author

Gladue, D. P., primary, Largo, E., additional, de la Arada, I., additional, Aguilella, V. M., additional, Alcaraz, A., additional, Arrondo, J. L. R., additional, Holinka, L. G., additional, Brocchi, E., additional, Ramirez-Medina, E., additional, Vuono, E. A., additional, Berggren, K. A., additional, Carrillo, C., additional, Nieva, J. L., additional, and Borca, M. V., additional

Published
2018
Full Text
View/download PDF

19. The utility of endovaginal sonography in the evaluation of fecal incontinence

Author

Ramírez, J. M., Aguilella, V., Martínez, M., and Gracia, J. A.

Subjects
Ecografía endovaginal, Sonography, Incontinencia fecal, Ecografía endoanal, Faecal incontinence, Ecografía, Endoanal sonography, Vaginal sonography
Abstract

Objective: the endoanal sonography in female patients with faecal incontinence is sometimes difficult and can lead to diagnostic errors. The aim of this study is to evaluate the value of endovaginal sonography in such cases. Material and method: thirty female patients complaining of faecal incontinence are included in the study. Anal endosonography was performed in all of them in a single ambulatory session, pictures were taken from all along the anal and results were analyzed afterward. Vaginal endosonography was then perfomed using the same equipment. Result from both techniques were compared. Results: endoanal sonography was performed in all 30 patients. In 17 cases no anomalies were found. In 3 patients a simple internal anal sphincter defect was found. One case showed a lateral lesion in both sphincters. Six cases presented anterior external defect and in the rest 3 cases a clear view of the anterior wall was imposible. Vaginal endosonography shows a clear image of the anal canal in 23 out of 30 patients. In two cases changed the results of anal endosonography. Conclusion: in the study of faecal incontinence, despite of its technical limitations, endovaginal ulltrasound could be of help when the anterior wall of the anal canal is not properly defined. Objetivo: el estudio ecográfico endoanal en la mujer con incontinencia fecal presenta en ocasiones dificultades que pueden llevar a errores de diagnóstico sobre todo cuando se valoran las imágenes de la cara anterior. En este trabajo nos hemos propuesto estudiar la eficacia de la ecografía endovaginal en estos casos. Material y método: treinta mujeres afectas de incontinencia fecal se incluyen en el estudio. Todas fueron exploradas en régimen ambulatorio mediante ecografía endoanal, tomando imágenes secuenciales del canal anal y analizando los resultados. Posteriormente, se realizó ecografía endovaginal con el mismo equipo y en la misma sesión. Se compararon los resultados de ambas técnicas. Resultados: en las 30 pacientes se pudo realizar la ecografía endoanal, en 17 enfermas no se hallaron anomalías. En 3 pacientes se apreció defecto único de esfínter anal interno. Una paciente presentaba defecto de ambos esfínteres latero-posterior. En 6 ocasiones se apreció defecto anterior de esfínter anal medio-alto. En otros 3 casos no se logró una buena visión del canal anal anterior. Con la ecografía endovaginal se apreció claramente el canal anal en 23 casos y no se consiguieron imágenes adecuadas en 7 y cambió el criterio de la ecografía endoanal en 2 ocasiones. Conclusión: en el estudio de la incontinencia fecal, la ecografía endovaginal a pesar de presentar limitaciones técnicas puede ser útil en los casos en los que se plantean dudas sobre la integridad de la pared anterior del conducto anal.

Published
2005

20. Doppler-guided hemorrhoidal artery ligation in the management of symptomatic hemorrhoids

Author

Ramírez, J. M., Aguilella, V., Elía, M., Gracia, J. A., and Martínez, M.

Subjects
Hemorrhoid artery ligation, Hemorroides, Doppler, Ligadura arteria hemorroidal, Hemorrhoids
Abstract

Objective: the aim of this study is to clinically test the efficacy of a new approach for patients having symptomatic grade III and IV hemorrhoids. Material and method: 32 patients (17 females) complaining of grade III or IV hemorrhoids were included in the study. A specially designed proctoscope coupled with a Doppler transducer on its tip was used to identify the hemorrhoidal arteries, which were afterwards suture ligated. Operating time as well as per- and post-operative complications were anlyzed. Follow-up was planned following discharge after 1 week, 1 month, 6 months and 1 year. Results: mean operation time was 27 (range 18-43) minutes, and 5 (range 4-7) arteries were located on average. No patient had severe or moderate postoperative pain, with anal discomfort being the main complaint. Rectal bleeding and tenesmus were the commonest post-operative complications. After one year of follow-up, 19 patients were free of symptoms and 6 of them had significant symptom relief. According to grade, the technique failed in just 3 grade III patients, but in as many as 4 grade IV hemorrhoid cases. Conclusions: doppler-guided hemorrhoid artery ligation is an easy-to-perform technique that is well accepted by patients and has good results for grade III hemorrhoids. Objetivo: el objetivo de este trabajo es valorar en la clínica la eficacia de una nueva técnica quirúrgica para el tratamiento de las hemorroides de grado III y IV. Material y método: se incluyen en el estudio 32 pacientes (17 mujeres), 27 presentaban hemorroides de grado III y 5 de grado IV. Para la técnica se utilizó un prostoscopio transparente que incorpora un transductor Doppler en su extremo para localizar las arterias hemorroidales que se ligan mediante puntos que engloban la mucosa y submucosa. Se analizó el tiempo de intervención y las complicaciones intra y postoperatorias, así como las recidivas. Los pacientes fueron controlados al alta, a la semana, mes, 6 meses y al año de la intervención. Resultados: el tiempo medio de intervención fue de 27 (rango 18-43) minutos, localizando de media 5 (rango 4-7) ramas arteriales. No existieron complicaciones intraoperatorias. Ningún paciente presentó dolor severo o moderado en alguno de los controles, refiriendo habitualmente molestias anales discretas. La rectorragia autolimitada y el tenesmo fueron las complicaciones post-operatorias más frecuentes. Tras el seguimiento a 1 año, 19 enfermos estaban asintomáticos y en 6 ocasiones los síntomas habían disminuido significativamente, en el resto la intervención fue ineficaz. Agrupados los pacientes por grados, la técnica presentó malos resultados en sólo 3 pacientes con hemorroides grado III, pero en hemorroides grado IV, los resultados fueron malos en 4 de los 5 pacientes. Conclusiones: la ligadura de la arteria hemorroidal guiada por Doppler es una técnica sencilla, bien tolerada, con buenos resultados en hemorroides grado III.

Published
2005

21. The utility of endovaginal sonography in the evaluation of fecal incontinence

Author

Ram̕rez, J.M., Aguilella, V., Mart̕nez, M., Gracia, J.A., Ram̕rez, J.M., Aguilella, V., Mart̕nez, M., and Gracia, J.A.

Abstract

Objective: the endoanal sonography in female patients with faecal incontinence is sometimes difficult and can lead to diagnostic errors. The aim of this study is to evaluate the value of endovaginal sonography in such cases. Material and method: thirty female patients complaining of faecal incontinence are included in the study. Anal endosonography was performed in all of them in a single ambulatory session, pictures were taken from all along the anal and results were analyzed afterward. Vaginal endosonography was then performed using the same equipment. Result from both techniques were compared. Results: endoanal sonography was performed in all 30 patients. In 17 cases no anomalies were found. In 3 patients a simple internal anal sphincter defect was found. One case showed a lateral lesion in both sphincters. Six cases presented anterior external defect and in the rest 3 cases a clear view of the anterior wall was imposible. Vaginal endosonography shows a clear image of the anal canal in 23 out of 30 patients. In two cases changed the results of anal endosonography. Conclusion: in the study of faecal incontinence, despite of its technical limitations, endovaginal ulltrasound could be of help when the anterior wall of the anal canal is not properly defined.

Published
2005

33. IMPLEMENTING ENVIRONMENTAL FLOWS IN COMPLEX WATER RESOURCES SYSTEMS - CASE STUDY: THE DUERO RIVER BASIN, SPAIN.

Author

Paredes‐Arquiola, J., Martinez‐Capel, F., Solera, A., and Aguilella, V.

Abstract

ABSTRACT European river basin authorities are responsible for the implementation of the new river basin management plans in accordance with the European Water Framework Directive. This paper presents a new methodology framework and approach to define and evaluate environmental flow regimes in the realistic complexities that exist with multiple water resource needs at a basin scale. This approach links river basin simulation models and habitat time series analysis to generate ranges of environmental flows (e-flows), which are evaluated by using habitat, hydropower production and reliability of water supply criteria to produce best possible alternatives. With the use of these tools, the effects of the proposed e-flows have been assessed to help in the consultation process. The possible effects analysed are impacts on water supply reliability, hydropower production and aquatic habitat. After public agreements, a heuristic optimization process was applied to maximize e-flows and habitat indicators, while maintaining a legal level of reliability for water resource demands. The final optimal e-flows were considered for the river basin management plans of the Duero river basin. This paper demonstrates the importance of considering quantitative hydrologic and ecological aspects of e-flows at the basin scale in addressing complex water resource systems. This approach merges standard methods such as physical habitat simulations and time series analyses for evaluating alternatives, with recent methods to simulate and optimize water management alternatives in river networks. It can be integrated with or used to complement other frameworks for e-flow assessments such as the In-stream Flow Incremental Methodology and Ecological Limits of Hydrologic Alteration. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Published
2013
Full Text
View/download PDF

35. Continuum electrostatic calculations of the pKa of ionizable residues in an ion channel: Dynamic vs. static input structure.

Author

Aguilella-Arzo, M. and Aguilella, V. M.

Subjects
ION channels, MOLECULAR dynamics, STAPHYLOCOCCUS aureus infections, BILAYER lipid membranes, SCISSION (Chemistry), STAPHYLOCOCCUS aureus
Abstract

We have computed the pKa’s of the ionizable residues of a protein ion channel, the Staphylococcus aureus toxin $ \alpha$ -hemolysin, by using two types of input structures, namely the crystal structure of the heptameric $ \alpha$ -hemolysin and a set of over four hundred snapshots from a 4.38ns Molecular Dynamics simulation of the protein inserted in a phospholipid planar bilayer. The comparison of the dynamic picture provided by the Molecular Simulation with the static one based on the X-ray crystal structure of the protein embedded in a lipid membrane allows analyzing the influence of the fluctuations in the protein structure on its ionization properties. We find that the use of the dynamic structure provides interesting information about the sensitivity of the computed pKa of a given residue to small changes in the local structure. The calculated pKa are consistent with previous indirect estimations obtained from single-channel conductance and selectivity measurements. [ABSTRACT FROM AUTHOR]

Published
2010
Full Text
View/download PDF

36. Reversal Potential of a Wide Ion Channel. Nonuniform Charge Distribution Effects

Author

Levadny, V. and Aguilella, V.

Abstract

A theory for the reversal potential Vr in a wide, charged ion channel (i.e., with radius comparable to channel length and Debye's length) embedded in a planar membrane is developed. We analyze the influence of a nonuniform channel charge distribution along the channel axis on Vr. The analysis is performed in the framework of the space charge model, which is generalized for axial nonuniform charge distributions. Two kinds of nonhomogeneity are considered:  (1) a symmetrical nonhomogeneous distribution when channel charge is uniformly smeared over the inner surface of channel wall, but it does not extend over the whole surface, and (2) an asymmetrical nonhomogeneous distribution corresponding to some part of the total charge uniformly smeared over the channel wall and some other located on one of the channel entrances. For the first distribution it is shown that even a small deviation from a uniform distribution leads to a significant change in the reversal potential. In particular, the experimentally observed nonmonotonic behavior of Vr for the voltage-dependent anion channel from mitochondria (VDAC) as a function of concentration gradient [Zambrowicz, E. B.; Colombini, M.; Biophys. J. 1993, 65, 1093.] is explained by invoking the axial nonhomogeneity of channel charge. For the second kind of distribution (which resembles that in VDAC closed states) it is shown that the sign and value of the reversal potential depends on the location of the mobile part of the channel charge. Theoretical results are compared with previously reported experimental data for VDAC but they are valid for any charged multiionic channel where the Nernst−Planck formalism can be applied.

Published
2001

39. Gibbs' Dividing Surface between a Fixed-Charge Membrane and an Electrolyte Solution. Application to Electrokinetic Phenomena in Charged Pores

Author

Aguilella, V. M., Pellicer, J., and Aguilella-Arzo, M.

Abstract

The Gibbs model for the boundary between two phases consists of replacing the finite interfacial region, where the properties of the system change gradually, by a dividing surface which acts as a third phase of zero volume in which some magnitudes change abruptly. This thermodynamic concept was recently applied to a planar interface between a fixed charge membrane and an electrolyte solution.1 The continuous decrease of counterions with the distance from the charged surface is replaced by a step function, so that the diffuse double layer is ideally represented by a charged region depleted of all co-ions. Here the cylindrical geometry is analyzed, and the planar case is revisited by proposing a slightly different step function for ion concentration. By starting from Boltzmann distributions of ions in solution, simple formulas are obtained for the distance between the charged interface and the dividing surface in both geometries. For the purpose of applying this model to charged, microporous membranes, expressions are given for some of the coefficients Lij of the Onsager phenomenological relations in a model membrane composed of identical, parallel, and cylindrical pores. A comparison is made between the values for conductance and streaming potential in a homogeneously charged pore predicted by the Gibbs model and the classical space charge model. Despite the obvious simplifications inherent to the model, good agreement is found for conductivity, while only qualitative agreement is found between streaming potential predictions.

Published
1999

42. Ion Permeability of a Membrane with Soft Polar Interfaces. 2. The Polar Zones as the Rate-Determining Step

Author

Levadny, V., Aguilella, V., Belaya, M., and Yamazaki, M.

Abstract

We have considered the ion transport across a membrane with extended soft permeable interfaces (polar zones), placed in an aqueous solution, under short-circuit conditions. The existence of fixed charges and dipoles in these membrane interfaces has been taken into account. The membrane has been modeled as composed of three layers:  an inner hydrophobic layer and two polar zones. Nernst−Planck's equation has been used for describing the ion transport. This paper continues our previous study, where we introduced the general model and analyzed the limit case of the internal hydrophobic layer as the rate-controlling step for ion transport (Langmuir 1996, 12, 4817). Here we have examined another limit case with the polar zones as the rate-controlling step for ion transport. The influence of the electrolyte concentration, the surface dipole density, and thickness of the polar zone on the total ion flux and permselectivity has been analyzed. It is shown that there are two significant differences with respect to the earlier considered limit case. On one hand, the steady-state condition leads to the build up of an additional space charge inside the polar zones, which influences considerably the ion transport. On the other hand, the membrane permselectivity exhibits a different variation with the electrolyte concentration. It is concluded that the analysis of permselectivity can help to find the rate-determining step in specific membrane systems.

Published
1998

44. Ion Permeability of a Membrane with Soft Polar Interfaces. 1. The Hydrophobic Layer as the Rate-Determining Step

Author

Aguilella, V., Belaya, M., and Levadny, V.

Abstract

We have considered the ion transport across a membrane with extended soft permeable interfaces (polar zones), placed in an aqueous solution, under short-circuit conditions. We have taken into account the existence of fixed charges and dipoles in these membrane interphases. The membrane has been modeled as composed of three layers:  an inner hydrophobic layer and two polar zones. Nernst−Planck's equation has been used for describing the ion transport, and Goldman's approximation has been assumed to be valid for the hydrophobic layer. In this paper the limiting case of the internal hydrophobic layer as the rate-controlling step for ion transport has been studied. The influence of the electrolyte concentration, the surface dipole density, and the thickness of the polar zone on the total ion flux and permselectivity has been analyzed. It has been shown that the permselectivity of such a system depends significantly on all these parameters. Particularly, the permselectivity of the same membrane changes with bulk electrolyte concentration. A general expression for cation selectivity has been obtained. The connection of the developed theory with experimental results has been discussed.

Published
1996

Catalog

Books, media, physical & digital resources
See catalog results