Evaluation of coated metallic bipolar plates for polymer electrolyte membrane fuel cells,”

Abstract Metallic bipolar plates for polymer electrolyte membrane (PEM) fuel cells typically require coatings for corrosion protection. Other requirements for the corrosion protective coatings include low electrical contact resistance, good mechanical robustness, low material and fabrication cost. The authors have evaluated a number of protective coatings deposited on stainless steel substrates by electroplating and physical vapor deposition (PVD) methods. The coatings are screened with an electrochemical polarization test for corrosion resistance; then the contact resistance test was performed on selected coatings. The coating investigated include Gold with various thicknesses (2 nm, 10 nm, and 1 m), Titanium, Zirconium, Zirconium Nitride (ZrN), Zirconium Niobium (ZrNb), and Zirconium Nitride with a Gold top layer (ZrNAu). The substrates include three types of stainless steel: 304, 310, and 316. The results show that Zr-coated samples satisfy the DOE target for corrosion resistance at both anode and cathode sides in typical PEM fuel cell environments in the short-term, but they do not meet the DOE contact resistance goal. Very thin gold coating (2 nm) can significantly decrease the electrical contact resistance, however a relatively thick gold coating (>10 nm) with our deposition method is necessary for adequate corrosion resistance, particularly for the cathode side of the bipolar plate

Evaluation of Coated Metallic Bipolar Plates for Polymer Electrolyte Membrane Fuel Cells

Metallic bipolar plates for polymer electrolyte membrane (PEM) fuel cells typically require coatings for corrosion protection. Other requirements for the corrosion protective coatings include low electrical contact resistance, good mechanical robustness, low material and fabrication cost. The authors have evaluated a number of protective coatings deposited on stainless steel substrates by electroplating and physical vapor deposition (PVD) methods. The coatings are screened with an electrochemical polarization test for corrosion resistance; then the contact resistance test was performed on selected coatings. The coating investigated include Gold with various thicknesses (2 nm, 10 nm, and 1 μm), Titanium, Zirconium, Zirconium Nitride (ZrN), Zirconium Niobium (ZrNb), and Zirconium Nitride with a Gold top layer (ZrNAu). The substrates include three types of stainless steel: 304, 310, and 316. The results show that Zr-coated samples satisfy the DOE target for corrosion resistance at both anode and cathode sides in typical PEM fuel cell environments in the short-term, but they do not meet the DOE contact resistance goal. Very thin gold coating (2 nm) can significantly decrease the electrical contact resistance, however a relatively thick gold coating (\u3e10 nm) with our deposition method is necessary for adequate corrosion resistance, particularly for the cathode side of the bipolar plate

Ácidos grasos omega-3 como coadyuvantes del tratamiento antidepresivo y sus efectos sobre el factor neurotrófico derivado del cerebro en suero y en células mononucleares Omega-3 fatty acids as adjunctive of antidepressant therapy and its effects on bra

El estrés disminuye el factor neurotrófico derivado del cerebro (BDNF) en el hipocampo; los antidepresivos y los ácidos grasos omega-3 podrían aumentarlo. En pacientes con depresión mayor, investigamos la respuesta clínica a un antidepresivo solo o con ácido eicosapentanoico (EPA), y su influencia sobre los niveles de BDNF. Veinte pacientes se diagnosticaron según el DSM-IV-TR; evaluamos la respuesta con la Escala de Hamilton para Depresión (HAM-D). Los controles fueron 15 sujetos sanos. Los pacientes se distribuyeron en 2 grupos: uno que recibió fluoxetina 20 mg/día y EPA 3.000 mg/día, y otro con fluoxetina 20 mg/día y placebo, durante 8 semanas. Se tomaron muestras de sangre en las semanas 0 y 8 para obtener suero, sin anticoagulante, para medir los niveles de BDNF, y para aislamiento de células mononucleares, con heparina, para la localización inmunocitoquímica de BDNF. Diez pacientes no continuaron por diferentes causas. De los 10 restantes, 5 recibieron EPA y 5, placebo. Una muestra no pudo ser procesada en el grupo con EPA. En ambos grupos hubo una reducción > 50 % en la HAM-D y una disminución significativa en los valores absolutos de la HAM-D en el grupo con EPA. El BDNF sérico antes del tratamiento fue significativamente inferior en los pacientes. El BNDF sérico disminuyó después de tratamiento en ambos grupos, más evidente en el grupo con EPA en el análisis pareado. El porcentaje de células mononucleares que expresaron BDNF fue inferior en los pacientes y aumentó después de los tratamientos. Por otra parte, las células con BDNF, las cuales estaban bajas en los deprimidos, aumentaron después de los tratamientos, lo que indica que en éstas, el papel del tratamiento, especialmente con la combinación del antidepresivo y el ácido en cuestión, las modificaciones en el BDNF son más evidentes. A pesar de la limitante que constituye la inclusión de los sujetos diagnosticados, más la permanencia de los incluidos, los resultados significativos señalan un efecto beneficioso del uso de EPA en la depresión mayor.Stress is associated with a decreased expression of brain-derived neurotrophic factor (BDNF) in the hippocampus. Antidepressants and omega-3 fatty acids might increase circulating BDNF. This research was done to evaluate, in major depression patients, the possible differences in clinical response to an antidepressant alone or in combination with eicosapentaenoic acid (EPA), and their influence on BDNF levels. Nineteen patients were diagnosed according to DSM-IV-TR criteria; severity and response was evaluated by Hamilton Depression Rating Scale (HAM-D). Control group was composed of 15 healthy subjects. Patients were randomized on a double-blind basis in two groups: one received fluoxetine 20 mg/day and EPA 3,000 mg/day, and the other one fluoxetine 20 mg/day and placebo, during 8 weeks. Blood samples were taken for obtaining serum and for isolating monocytes and lymphocytes at weeks 0 and 8. Ten patients dropped out for different causes. Of the remaining 9 subjects, 4 received EPA and 5 got placebo. In both groups there was a reduction > 50% in the HAM-D and a significant decrease in absolute values of HAM-D in the EPA group. Serum BDNF before treatment was significantly lower in patients than in controls. The percentage of mononuclear cells expressing BDNF was lower in patients, and it was significantly increased after the treatments. EPA seems to augment the clinical response. In depressed, after treatment, there was a lower content of serum BDNF. Moreover, mononuclear cells with BDNF, which were lower in this group of depressed, increased after the treatments, indicating that in cells the modulation of BDNF by antidepressants is more evident