Corrosion behavior of tantalum coatings on AISI 316L stainless steel substrate for bipolar plates of PEM fuel cells

Corrosion resistance of tantalum coatings 30 μm thick deposited by chemical vapor deposition on SS316L coupons has been evaluated by electrochemical impedance spectroscopy (EIS). To this end, anodic and cathodic operating conditions of proton exchange membrane fuel cells (PEMFC) have been simulated in a three-electrode heated corrosion cell. Interfacial contact resistance (ICR), contact angle and durability tests have been performed in long-term tests (> 100 h) polarizing the electrode to 1.193 V vs. Ag/AgCl. Results obtained by different experimental techniques show a dense coating structure with a high polarization resistance, mainly formed by surface crystals of α-Ta (bcc), Ta2O5 and carbon. An atomic ratio (in %) of oxide to metallic species (Taox/Tamet) of 4.8 was verified from XPS spectra, which is slightly increased to 6.23 after the anodizing treatment. The modified surface composition yielded a coating capacity higher than the amorphous oxide, favoring the in-plane electrical conduction. After the treatment, no noticeable changes were observed neither in surface morphology nor in contact angle (>90°). ICR values in the range of 22.3 − 32.6 mΩ cm2 were obtained for a clamping pressure of 140 N cm-2. No morphological changes or loss of coating adherence were observed during the long-term tests

Electronic modeling of a PEMFC with logarithmic amplifiers

The main purpose of this project has been to simulate the behavior of a PEM-type fuel cell working in a stationary regimen using an equivalent circuit (EC). The EC designed with Multisim circuit design software reproduces the three characteristics sections of a polarization curve for a proton exchange membrane fuel cell (PEMFC). The main characteristic of this EC is that it offers the possibility to adapt the power range of the fuel cell in the simulated electronic model. To do so, a transconductance is used to allow adjusting the load current range. The EC allows fitting the simulated results to any commercial PEM fuel cell polarization curves and power ranges, adjusting parameters such as the charge current IFC and the reversible voltage of the PEM fuel cell Erev, and then setting the resistor values in the losses blocks and in the amplifiers. Validation of the EC has been performed by simply adjusting the empirical data obtained with an Electrochem commercial 25 cm2 active area PEMFC to the different analog blocks of the EC. Adjustments were carried out by using Mathcad 14 calculation algorithms

Valor nutritivo del garbanzo crudo y extrusionado en pollos de aptitud cárnica

Se realizó un experimento con el objeto de estudiar el efecto de la inclusión de distintas concentraciones (0, 100, 200 y 300 g kg-1) de garbanzo crudo y extrusionado sobre los parámetros productivos, el peso y la longitud de los órganos digestivos y la digestibilidad de la proteína y la grasa de pollos broiler (0-21 días de edad). Los datos fueron analizados siguiendo un diseño factorial (3 x 2) con tres concentraciones de garbanzo con o sin extrusión. Se utilizó una dieta basada en maízsoja como control positivo sin garbanzo. La inclusión de cantidades crecientes de garbanzo en la dieta no modificó la ganancia de peso, el consumo de alimento ni el índice de transformación de las aves, pero sí los pesos relativos del páncreas e hígado y las longitudes relativas del duodeno, yeyuno, íleon y ciego que se incrementaron significativamente (P<0,05). La digestibilidad aparente ileal (AID) de la proteína bruta (CP) y la digestibilidad aparente fecal (AED) de la grasa bruta (CF) se incrementaron (P<0,05) sólo en el caso de la incorporación de 200 g kg-1 de garbanzo. La extrusión mejoró la ganancia de peso de las aves, la AID (P<0,001) de la CP y la AED de la CF y disminuyó (P<0,05) el peso relativo del páncreas. En conclusión, la inclusión de hasta 300 g kg-1 de garbanzo no produjo modificaciones en los parámetros productivos de las aves y causó efectos negativos en algunos órganos digestivos.The effects of the inclusion of different concentrations (0, 100, 200 and 300 g kg(-1)) of raw and extruded chickpeas on performance, digestive organ sizes, and protein and fat digestibilities were studied in one experiment with growing broiler chickens (0 to 21 days of age). Data were analyzed as a 3 x 2 factorial arrangement with three levels of chickpea with or without extrusion. A corn-soybean based diet was used as a positive control. Increasing chickpea content in the diet did not affect weight gain, feed consumption and feed to gain ratio. Relative pancreas and liver weights, and relative lengths of duodenum, jejunum and ceca were significantly (P<0.05) increased in response to increasing chickpea concentration in the diet. The inclusion of graded concentrations of chickpea increased (P<0.05) the apparent ileal digestibility (AID) of crude protein (CP) and apparent excreta digestibility (AED) of crude fat (CF) only in the case of the intermediate level of chickpea used (200 g kg(-1)). Extrusion improved weight gain and lowered relative pancreas weight (P<0.05) respect to birds fed raw chickpea-based diets. AID of CP and AED of CF were improved (P<0.001) by extrusion. We concluded that the inclusion of up to 300 g kg(-1) chickpea in chicken diets did not affect performance, and caused a negative effect on the relative weight of some digestive organs.The authors thank the Ministerio de Educación y Ciencia for financial support of this investigation (project INIARTA 03-202)

Effect of a diet supplemented with sphingomyelin and probiotics on colon cancer development in mice

Previous studies have reported that dietary sphingomyelin could inhibit early stages of colon cancer. Lactic acid–producing bacteria have also been associated with an amelioration of cancer symptoms. However, little is known about the potential beneficial effects of the combined administration of both sphingomyelin and lactic acid–producing bacteria. This article analyzes the effect of a diet supplemented with a combination of the probiotics Lacticaseibacillus casei and Bifidobacterium bifidum (108 CFU/ml) and sphingomyelin (0.05%) on mice with 1,2-dimethylhydrazine (DMH)-induced colon cancer. Thirty-six BALB/c mice were divided into 3 groups: one healthy group (group C) and two groups with DMH-induced cancer, one fed a standard diet (group D) and the other fed a diet supplemented with sphingomyelin and probiotics (DS). The number of aberrant crypt foci, marker of colon cancer development, was lower in the DS. The dietary supplementation with the synbiotic reversed the cancer-induced impairment of galactose uptake in enterocyte brush–border–membrane vesicles. These results confirm the beneficial effects of the synbiotic on the intestinal physiology of colon cancer mice and contribute to the understanding of the possible mechanisms involved.This study was supported by the Government of Spain grant number AGL 2006–1029-C02-01/ALI, CIBER (CB12/03/30002) and the Department of Innovation, Business and Employment of the Government of Navarra (Spain)

Evaluation of the corrosion resistance of Ni(P)Cr coatings for bipolar plates by electrochemical impedance spectroscopy

Trabajo presentado en el VII Symposium on Hydrogen, Fuel Cells and Advanced Batteries (HYCELTEC 2019), celebrado en Barcelona del 1 al 3 de julio de 2019.This research has been supported by the MEC, DPI2015-69286-C3-1-R (MINECO/FEDER, UE). Technical and human support of the Materials and Surfaces service provided by SGIker (UPV/EHU/ ERDF, EU) is also appreciated

Fat-to-glucose interconversion by hydrodynamic transfer of two glyoxylate cycle enzyme genes

The glyoxylate cycle, which is well characterized in higher plants and some microorganisms but not in vertebrates, is able to bypass the citric acid cycle to achieve fat-to-carbohydrate interconversion. In this context, the hydrodynamic transfer of two glyoxylate cycle enzymes, such as isocytrate lyase (ICL) and malate synthase (MS), could accomplish the shift of using fat for the synthesis of glucose. Therefore, 20 mice weighing 23.37 +/- 0.96 g were hydrodinamically gene transferred by administering into the tail vein a bolus with ICL and MS. After 36 hours, body weight, plasma glucose, respiratory quotient and energy expenditure were measured. The respiratory quotient was increased by gene transfer, which suggests that a higher carbohydrate/lipid ratio is oxidized in such animals. This application could help, if adequate protocols are designed, to induce fat utilization of obesity and diabetes

Difusión del software libre en la universidad : la experiencia piloto Moodle en la Universidad del País Vasco

La experiencia piloto Moodle UPV/EHU que aquí se presenta, comenzó en 2003 impulsada por un pequeño grupo de profesores apoyados por el centro informático de la universidad (CIDIR). Este grupo ha colaborado de manera desinteresada con los profesores investigadores de la Universidad que han solicitado su ayuda en el uso de Moodle, ofreciéndoles soporte técnico y formación. A partir del curso 2004-2005, este colectivo de profesores ha conformado el Grupo iKide. En este artículo se muestra cómo la filosofía del software libre puede ayudar a impulsar la innovación docente.The UPV-EHU Moodle pilot experience presented in this paper was set up in 2003, driven by a small group of lecturers with the help of the Computer Centre of the UPV/EHU (CIDIR). This group has voluntarily collaborated with those university teachers who were interested in working with Moodle and offered them technical support and training. From the course 2004-2005 onwards, the foremencioned group of lecturers became the iKide Group. This paper shows how Open Source philosophy can help to foster teaching innovation