200 research outputs found
Evolution of the critical oxygen tension
No full textChang, A.; Compañ Moreno, V.; Weissman, BA. (2018). Evolution of the critical oxygen tension. Contact Lens Spectrum. 33(3):36-39. https://riunet.upv.es/handle/10251/121358S363933
Permeability of coextruded LLDPE films to oxygen and carbon dioxide as determined by electrochemical techniques
No full textCompañ Moreno, V.; Ribes-Greus, A.; Díaz Calleja, R.; Riande, E. (1996). Permeability of coextruded LLDPE films to oxygen and carbon dioxide as determined by electrochemical techniques. Polymer. 37(11):2243-2250. doi:10.1016/0032-3861(96)85870-8S22432250371
Diseño interior de un establecimiento de restauración
No full textEl objeto del proyecto es diseñar la cocina de Flor de Cotó, un restaurante de nueva
implantación situado en Alzira.
El restaurante ofrece comida mediterránea; arroces, carnes y pescados. Pese a que el tipo
de cocina es muy tradicional, el local está ambientado de una manera muy peculiar, con un
estilo nórdico y vanguardista.
En el presente proyecto se expone tanto la distribución de la cocina y su instalación como el
resto del local. Para ello se hace un estudio previo de las necesidades y organización de las
diferentes zonas.
Con este proyecto se pretende mejorar la cocina para ahorrar tiempo a la hora de cocinar y a
su vez hacer que los trabajadores hagan su faena más cómodamente; atraer a los clientes por
la estética del restaurante y una vez dentro enamorarles con la comida.
También se pretende romper la barrera entre cocineros y clientes acercando al comensal a
los fogones, dejando la cocina a la vista, permitiéndoles ver todo el proceso de elaboración,
así como la maquinaria que lo equipa y las condiciones higiénicas en las que se encuentra.Morlanés Compañ, V. (2015). Diseño interior de un establecimiento de restauración. Universitat Politècnica de València. https://riunet.upv.es/handle/10251/61200Archivo delegad
On the methanol permeability through pristine Nafion and Nafion/PVA membranas measured by different techniques. A comparison of methodologies
No full text[EN] Methanol crossover through polymer electrolyte membranes
is a critical issue and causes an important reduction of per-
formance in direct methanol fuel cells (DMFCs). Measuring
the evolution of CO
2
gas in the cathode is a common method
to determine the methanol crossover under real operating
conditions, although an easier and simpler method is prefer-
able for the screening of membranes during their step of
development. In this sense, this work has been focused on
the
ex situ
characterization of the methanol permeability in
novel nanofiber-reinforced composite Nafion/PVA mem-
branes for DMFC application by means of three different
experimental procedures: (a) potentiometric method, (b) gas
chromatography technique, and (c) measuring the density. It
was found that all these methods resulted in comparable
results and it was observed that the incorporation of the
PVA nanofiber phase within the Nafion
¿
matrix causes a
remarkable reduction of the methanol permeability. The
optimal choice of the most suitable technique depends on
the accuracy expected for the methanol concentration, the
availability of the required instrumental, and the complexity
of the procedure.This work has been supported by the Valencian Institute of Small and Medium-Sized Enterprises (IMPIVA) and the European Regional Development Funds, through the project IMIDIC/2010/13.Mollá Romano, S.; Compañ Moreno, V.; Lafuente, S.; Prats, J. (2011). On the methanol permeability through pristine Nafion and Nafion/PVA membranas measured by different techniques. A comparison of methodologies. Fuel Cells. 11(6):897-906. https://doi.org/10.1002/fuce.201100004S897906116Handbook of Fuel Cells-Fundamentals, Technology and Applications Vol. 3 2003Neergat, M., Leveratto, D., & Stimming, U. (2002). Catalysts for Direct Methanol Fuel Cells. Fuel Cells, 2(1), 25-30. doi:10.1002/1615-6854(20020815)2:13.0.co;2-4Mauritz, K. A., Mountz, D. A., Reuschle, D. A., & Blackwell, R. I. (2004). Self-assembled organic/inorganic hybrids as membrane materials. Electrochimica Acta, 50(2-3), 565-569. doi:10.1016/j.electacta.2003.09.051Deng, Q., Hu, Y., Moore, R. B., McCormick, C. L., & Mauritz, K. A. (1997). Nafion/ORMOSIL Hybrids viain SituSol−Gel Reactions. 3. Pyrene Fluorescence Probe Investigations of Nanoscale Environment. Chemistry of Materials, 9(1), 36-44. doi:10.1021/cm950552uKim, Y.-M., Park, K.-W., Choi, J.-H., Park, I.-S., & Sung, Y.-E. (2003). A Pd-impregnated nanocomposite Nafion membrane for use in high-concentration methanol fuel in DMFC. Electrochemistry Communications, 5(7), 571-574. doi:10.1016/s1388-2481(03)00130-9Smit, M. A., Ocampo, A. L., Espinosa-Medina, M. A., & Sebastián, P. J. (2003). A modified Nafion membrane with in situ polymerized polypyrrole for the direct methanol fuel cell. Journal of Power Sources, 124(1), 59-64. doi:10.1016/s0378-7753(03)00730-4Chen, C.-Y., Garnica-Rodriguez, J. I., Duke, M. C., Costa, R. F. D., Dicks, A. L., & da Costa, J. C. D. (2007). Nafion/polyaniline/silica composite membranes for direct methanol fuel cell application. Journal of Power Sources, 166(2), 324-330. doi:10.1016/j.jpowsour.2006.12.102Fernández-Carretero, F. J., Compañ, V., & Riande, E. (2007). Hybrid ion-exchange membranes for fuel cells and separation processes. Journal of Power Sources, 173(1), 68-76. doi:10.1016/j.jpowsour.2007.07.011DELUCA, N., & ELABD, Y. (2006). Nafion®/poly(vinyl alcohol) blends: Effect of composition and annealing temperature on transport properties. Journal of Membrane Science, 282(1-2), 217-224. doi:10.1016/j.memsci.2006.05.025Mollá, S., & Compañ, V. (2011). Performance of composite Nafion/PVA membranes for direct methanol fuel cells. Journal of Power Sources, 196(5), 2699-2708. doi:10.1016/j.jpowsour.2010.11.022Kreuer, K.-D. (1996). Proton Conductivity: Materials and Applications. Chemistry of Materials, 8(3), 610-641. doi:10.1021/cm950192aSnyder, J. (2002). Polymer electrolytes and polyelectrolytes: Monte Carlo simulations of thermal effects on conduction. Solid State Ionics, 147(3-4), 249-257. doi:10.1016/s0167-2738(02)00025-5Paddison, S. J. (2003). Proton Conduction Mechanisms at Low Degrees of Hydration in Sulfonic Acid–Based Polymer Electrolyte Membranes. Annual Review of Materials Research, 33(1), 289-319. doi:10.1146/annurev.matsci.33.022702.155102Proton Conducting Membrane Fuel Cells 1995Jiang, R., & Chu, D. (2002). CO[sub 2] Crossover Through a Nafion Membrane in a Direct Methanol Fuel Cell. Electrochemical and Solid-State Letters, 5(7), A156. doi:10.1149/1.1480136Qi, Z., & Kaufman, A. (2002). Open circuit voltage and methanol crossover in DMFCs. Journal of Power Sources, 110(1), 177-185. doi:10.1016/s0378-7753(02)00268-9Eccarius, S., Garcia, B. L., Hebling, C., & Weidner, J. W. (2008). Experimental validation of a methanol crossover model in DMFC applications. Journal of Power Sources, 179(2), 723-733. doi:10.1016/j.jpowsour.2007.11.102Tamaki, T., Yamauchi, A., Ito, T., Ohashi, H., & Yamaguchi, T. (2011). The Effect of Methanol Crossover on the Cathode Overpotential of DMFCs. Fuel Cells, 11(3), 394-403. doi:10.1002/fuce.201000141Pivovar, B. S., Wang, Y., & Cussler, E. L. (1999). Pervaporation membranes in direct methanol fuel cells. Journal of Membrane Science, 154(2), 155-162. doi:10.1016/s0376-7388(98)00264-6Schaffer, T., Hacker, V., Hejze, T., Tschinder, T., Besenhard, J. O., & Prenninger, P. (2005). Introduction of an improved gas chromatographic analysis and comparison of methods to determine methanol crossover in DMFCs. Journal of Power Sources, 145(2), 188-198. doi:10.1016/j.jpowsour.2004.11.074Zhang, J., & Wang, Y. (2004). Modeling the Effects of Methanol Crossover on the DMFC. Fuel Cells, 4(12), 90-95. doi:10.1002/fuce.200400005Casalegno, A., Grassini, P., & Marchesi, R. (2007). Experimental analysis of methanol cross-over in a direct methanol fuel cell. Applied Thermal Engineering, 27(4), 748-754. doi:10.1016/j.applthermaleng.2006.10.007García, B. L., Sethuraman, V. A., Weidner, J. W., White, R. E., & Dougal, R. (2004). Mathematical Model of a Direct Methanol Fuel Cell. Journal of Fuel Cell Science and Technology, 1(1), 43. doi:10.1115/1.1782927Munichandraiah, N., McGrath, K., Prakash, G. K. S., Aniszfeld, R., & Olah, G. A. (2003). A potentiometric method of monitoring methanol crossover through polymer electrolyte membranes of direct methanol fuel cells. Journal of Power Sources, 117(1-2), 98-101. doi:10.1016/s0378-7753(03)00353-7Bello, M., Zaidi, S. M. J., & Rahman, S. U. (2008). Proton and methanol transport behavior of SPEEK/TPA/MCM-41 composite membranes for fuel cell application. Journal of Membrane Science, 322(1), 218-224. doi:10.1016/j.memsci.2008.05.042Liu, J., Wang, H., Cheng, S., & Chan, K.-Y. (2005). Nafion–polyfurfuryl alcohol nanocomposite membranes for direct methanol fuel cells. Journal of Membrane Science, 246(1), 95-101. doi:10.1016/j.memsci.2004.08.016Mollá, S., & Compañ, V. (2011). Polyvinyl alcohol nanofiber reinforced Nafion membranes for fuel cell applications. Journal of Membrane Science, 372(1-2), 191-200. doi:10.1016/j.memsci.2011.02.001Garrido, J., & Compan, V. (1992). Asymmetry potential in inhomogeneous membranes. The Journal of Physical Chemistry, 96(6), 2721-2724. doi:10.1021/j100185a059Wakabayashi, N., Uchida, H., & Watanabe, M. (2002). Temperature-Dependence of Methanol Oxidation Rates at PtRu and Pt Electrodes. Electrochemical and Solid-State Letters, 5(11), E62. doi:10.1149/1.1513021Mukoma, P., Jooste, B. R., & Vosloo, H. C. M. (2004). A comparison of methanol permeability in Chitosan and Nafion 117 membranes at high to medium methanol concentrations. Journal of Membrane Science, 243(1-2), 293-299. doi:10.1016/j.memsci.2004.06.032Kim, D. W., Choi, H.-S., Lee, C., Blumstein, A., & Kang, Y. (2004). Investigation on methanol permeability of Nafion modified by self-assembled clay-nanocomposite multilayers. Electrochimica Acta, 50(2-3), 659-662. doi:10.1016/j.electacta.2004.01.125Tsai, J.-C., Cheng, H.-P., Kuo, J.-F., Huang, Y.-H., & Chen, C.-Y. (2009). Blended Nafion®/SPEEK direct methanol fuel cell membranes for reduced methanol permeability. Journal of Power Sources, 189(2), 958-965. doi:10.1016/j.jpowsour.2008.12.071EVERY, H., HICKNER, M., MCGRATH, J., & ZAWODZINSKIJR, T. (2005). An NMR study of methanol diffusion in polymer electrolyte fuel cell membranes. Journal of Membrane Science, 250(1-2), 183-188. doi:10.1016/j.memsci.2004.10.026Ramya, K., & Dhathathreyan, K. S. (2008). Methanol crossover studies on heat-treated Nafion® membranes. Journal of Membrane Science, 311(1-2), 121-127. doi:10.1016/j.memsci.2007.12.00
Polyvinyl alcohol nanofiber reinforced Nafion membranes for fuel cell applications
No full textThis work has been focused on the preparation and characterization of composite membranes with thickness between 19 and 97 mu m and containing Nafion(R) infiltrated into a porous mat obtained by electrospinning of an aqueous solution of Poly vinyl alcohol (PVA). The mat was composed of PVA nanofibers with diameters between 200 and 300 nm, which were functionalized on their external surface with sulfonic acid groups in order to cooperate in the proton conductivity of Nafione(R). The proton conductivity of a composite membrane (47 mu m thick) measured by impedance spectroscopy reached 0.022 S/cm at 70 degrees C and fully hydrated. This value is lower than the conductivity measured in the same conditions for a pristine Nafion(R) cast membrane (46 mu m), 0.032 S/cm. However, the performance of both membranes in Direct Methanol Fuel Cell tests was evaluated and showed comparable results. The proton conductivity of a series of cast Nafion(R) membranes with thickness similar to those of the composite membranes was found to behave linearly thickness-dependent, while NAF/PVA composite membranes do not show such a linear behavior due to their heterogeneous composition. Nevertheless, the composite membrane presenting a thickness of 47 mu m records the maximum peak conductivities at the whole temperature range. An intrinsic value for the activation energy of our cast Nafion(R) membranes at fully hydrated conditions was estimated to be 7 kJ/mol.This work has been supported by the Valencian Institute of Small and Medium-Sized Enterprises (IMPIVA) and the European Regional Development Funds, through the project IMIDIC/2009/155.Mollá Romano, S.; Compañ Moreno, V. (2011). Polyvinyl alcohol nanofiber reinforced Nafion membranes for fuel cell applications. Journal of Membrane Science. 372(1-2):191-200. https://doi.org/10.1016/j.memsci.2011.02.001S1912003721-
Pepita Reyes : comedia en dos actos
No full textNúmero extraordinarioDatos del impresor: No v. da capa: año I, 5 de agosto de 1916, núm., 31No v. da capa: Foto. Compañ
Polymer blends of SPEEK for DMFC application at intermediate temperatures
No full text[EN] Sulfonated poly(ether–ether–ketone) materials (SPEEK) are good proton conductors at high degrees of sulfonation and appropriate for high temperature application due to their glass transition temperatures around 200 °C. Nevertheless, high degrees of sulfonation result in excessive swelling and dissolution of the membranes in hot water, preventing their potential use for direct methanol fuel cells. One possible remedy is their chemical stabilization. For this reason, blends of SPEEK with PVA (polyvinyl alcohol), a hydrophilic polymer, were prepared and tested. Above 25 wt% PVA, the membranes were found to be mechanically stable in boiling water, with acceptable proton conductivities but excessive methanol permeabilities. On the other hand, blends of SPEEK with a hydrophobic polymer, PVB (polyvinyl butyral), resulted in extremely stable membranes in boiling water above a 30 wt% PVB content. Those membranes presented excellent mechanical and methanol barrier properties while proton conductivities were very low. A discussion of possible ways to make optimal use of these materials is presented.This research has been funded in the frame of Support Programme for Research and Development of the Polytechnic University of Valencia and the Ministry of Science and Innovation through the projects: 24761 and SP-ENE-20120718, respectively.Mollá Romano, S.; Compañ Moreno, V. (2014). Polymer blends of SPEEK for DMFC application at intermediate temperatures. International Journal of Hydrogen Energy. 39(10):1-16. https://doi.org/10.1016/j.ijhydene.2014.01.085S116391
Nanocomposite SPEEK-based membranes for Direct Methanol Fuel Cells at intermediate temperatures
No full textNovel nanocomposite membranes were prepared by infiltration of a blend of sulfonated PEEK (SPEEK) with polyvinyl alcohol (PVA), using water as solvent, into electrospun nanolibers of SPEEK blended with polyvinyl butyral (PVB). The membranes were characterized for their application on Direct Methanol Fuel Cells (DMFCs) operating at moderate temperatures (>80 degrees C). An important role of the solvent on the crosslinking temperature for the SPEEK-PVA system was observed. A mat of hydrated SPEEK-30%PVB nanofibers revealed higher proton conductivity in comparison with a dense membrane of similar composition. Incorporation of the nanoliber mats to the SPEEK-35%PVA matrix provided mechanical stability, methanol barrier properties and certain proton conductivity up to a crosslinking temperature of 120 degrees C. Not remarkable effect of the nanofibers was found above that crosslinking temperature. The combined effect of the nanofibers and crosslinking temperature on the properties of the membranes is discussed. DIV1FC performance experiments concluded promising results for this new low-cost type of membranes, although further optimization steps are still required.This research has been funded by the R&D Support Programmes of the Polytechnic University of Valencia (project 24761) and the Spanish Ministry of Science and Innovation (project SP-ENE-20120718).Mollá Romano, S.; Compañ Moreno, V. (2015). Nanocomposite SPEEK-based membranes for Direct Methanol Fuel Cells at intermediate temperatures. Journal of Membrane Science. 492:123-136. https://doi.org/10.1016/j.memsci.2015.05.055S12313649
Oxygen, water and sodium chloride transport in Soft Contact Lenses Materials
No full text[EN] Oxygen permeability, diffusion coefficient of the sodium ions and water flux and permeability in different conventional hydrogel (Hy) and silicone-hydrogel (Si-Hy) contact lenses have been measured experimentally. The results showed that oxygen permeability and transmissibility requirements of the lens have been addressed through the use of siloxane containing hydrogels. In general, oxygen and sodium chloride permeability values increased with the water content of the lens but there was a percolation phenomenon from a given value of water uptake mainly in the Si-Hy lenses which appeared to be related with the differences between free water and bound water contents. The increase of ion permeability with water content did not follow a unique trend indicating a possible dependence of the chemical structure of the polymer and character ionic and non-ionic of the lens. Indeed, the salt permeability values for silicone hydrogel contact lenses were one order of magnitude below those of conventional hydrogel contact lenses, which can be explained by a diffusion of sodium ions occurring only through the hydrophilic channels. The increase of the ionic permeability in Si-Hy materials may be due to the confinement of ions in nanoscale water channels involving possible decreased degrees of freedom for diffusion of both water and ions. In general, ionic lenses presented values of ionic permeability and diffusivity higher than most non-ionic lenses. The tortuosity of the ionic lenses is lower than the non-ionic Si-Hy lenses. Frequency 55 and PureVision exhibited the highest water permeability and flux values and, these parameters were greater for ionic Si-Hy lenses than for ionic conventional hydrogel lenses.Gavara, R.; Compañ Moreno, V. (2016). Oxygen, water and sodium chloride transport in Soft Contact Lenses Materials. Journal of Biomedical Materials Research Part B Applied Biomaterials. 105(8):2218-2231. doi:10.1002/jbm.b.33762S22182231105
Generalized friction forces in electrochemical and gravitational non-equilibrium systems with or without temperature gradients
No full text[EN] A formalism is developed for the treatment of general, vectorial transport phenomena of the energetic quantities of Brønsted in nonelectrolyte or electrolyte systems with or without temperature gradients, gravitational or electric fields, and with or without a membrane matrix present. The treatment is based in the properties of so-called generalized friction forces between the streaming components and between these and the streaming entropy. The role of the proper form of the Gibbs¿Duhem equation in such systems is discussed in prolongation of the treatment of Sørensen and Compañ[Electrochim. Acta42, 639¿649 (1997)]. It is shown that the local dissipation may be expressed in the usual bilinear form of fluxes and forces, but this form is derived from the fact that the dissipation is the work performed against the generalized friction forces. The relation between the Galilei invariance and the noninvertibility of the phenomenological equations as well as the overall balance of the friction forces is stressed. The formalism is used to derive expressions for the electromotoric force in isothermal electrochemical cells with a membrane separator and gravitational forces included, for thermoosmotic effects and thermodiffusion of salts in membranes and for thermoelectromotive forces over membranes. Suitable ¿quantities of transport¿ are defined in nonisothermal systems. Using the ¿quasi-thermostatic method¿ of Helmholtz, Thomson and Brønsted and using the present formalism lead to the same results. Single ion activities cannot be found experimentally neither from isothermal nor from nonisothermal measurements of electromotive force.This work has been supported by the Dirección General de Investigación en Ciencia y Tecnología, DGICYT (Ministry of Education and Science of Spain) under project PB92-0773-C03-03 and by BANCAJA under project P1B95-004. T.S.S. is indebted to DGICYT for a sabbatical year guest professorate enabling him to do research at the Universitat Jaume I, Castellon, Spain. Furthermore, T.S.S. as well as V.C. are grateful to the University of Concepción and to the Intercampus Exchange Programme (Spain-Latin America) for economic support for a 1 month stay in Chile.Sorensen, TS.; Compañ Moreno, V.; Rivera, SR. (1998). Generalized friction forces in electrochemical and gravitational non-equilibrium systems with or without temperature gradients. Electrochimica Acta. 43(8):951-956. https://doi.org/10.1016/S0013-4686(97)00214-4S95195643
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