Development of Method for Synthesis of Pt–Co Cathode Catalysts for PEM Fuel Cells

A procedure was developed to synthesize a platinum–cobalt (Pt–Co) alloy electrocatalyst for oxygen reduction using Co/C composite as a support. The Pt–Co/C catalysts were synthesized through: (i) chemical oxidation of carbon black, (ii) Co deposition on the oxidized carbon using a chelation method, (iii) chemical treatment in an acidic medium to remove excess of Co on the carbon surface, (iv) Pt deposition onto the Co/C support, and (v) postheat treatment to form the Pt–Co alloy catalyst. The synthesized Pt–Co/C catalyst showed improved activity and long-term stability in polymer electrolyte membrane (PEM) fuel cells when compared with a conventional Pt–Co/C catalyst. The electron probe microanalysis combined with scanning electron microscopy indicated that the Co content in the alloy catalyst remains stable without poisoning of the electrolyte membrane during long-term operation

Diferencia de presentación del síndrome coronario agudo por género en pacientes llevados al laboratorio de cateterismo en población dominicana: un estudio retrospectivo

Introducción: el síndrome coronario agudo (SCA) es una serie de signos y síntomas que se refieren a isquemia miocárdica repentina. Estas condiciones clínicas son Síndrome Coronario agudo sin Elevación del Segmento ST (SCASEST) y Síndrome Coronario Agudo con Elevación del Segmento ST (SCACEST). A nivel mundial hay hallazgos controversiales con respecto a la diferencia de presentación de SCA en hombres y mujeres. Objetivo: determinar las diferencias en presentación del síndrome coronario agudo según el género en República Dominicana. Métodos: en este estudio observacional retrospectivo unicéntrico, 3,548 pacientes con SCA llevados al laboratorio de cateterismo fueron observados durante el período de agosto de 2016 a septiembre de 2019. Resultados: la edad promedio de presentación fue mayor en las mujeres, con una media de 63 años (DE ± 12.2). El SCACEST fue más frecuente en hombres (69.35 %) y la Angina Inestable en mujeres (50.14 %, p <0.0001). Angiográficamente, la enfermedad coronaria multivascular fue más común en hombres y la angiografía coronaria normal en mujeres (41.30 % y 35.37 %, p <0.0001). Conclusión: dentro de la población dominicana, la mujer tiende a ser mayor al momento de presentación de SCA, con menor tendencia a someterse a intervención coronaria terapéutica

NeuroBoricuas: a novel approach for incorporating neuroscience education in schools of Puerto Rico

[EN] Puerto Rico is in dire need of transforming its education system to counter the current economic recession and ensure a future with talented Puerto Ricans at the forefront of scientific research and technology development.  Here we present a group of neuroscientists and educators, the NeuroBoricuas, committed to revolutionize the scientific culture of Puerto Rico by incorporating neuroscience research training and inquiry-based activities in public and private schools. We carry out our vision through diverse methods, such as community outreach activities, where we promote neuroscience literacy using diverse learning activities. In parallel, we are designing a neuroscience course and textbook with educators to be implemented in schools. We also established neuroscience laboratories in K-12 schools and trained science teachers to manage such laboratories, using equipment from the company “Backyard Brains”. These laboratory experiences are integrated into the academic curriculum in high schools and the equipment is also available for students interested in designing their independent research projects. Lastly, we are expanding a network of committed scientists who partner with educators to help nurture future neuroscientists early in their academic endeavors. Here, we describe our trajectory and our approach to transform scientific education in Puerto Rico.We thank Dr. Gregory J. Quirk, Dr. Daniel Colon-Ramos and Dr. Mark Miller for their support. We thank Tim Marzullo, from Backyard Brains, for supporting NeuroBoricuas. We also thank Palabreria, Digi-Serv and Puerto Rico 4.0 for their constant support. We thank all the NeuroBoricuas that selflessly work hard for a better Puerto Rico. This work has been supported by generous donations from the Puerto Rican people, a grant from the University of Puerto Rico Medical Sciences Campus’ Chancellor’s office, and the Grass Foundation.http://ocs.editorial.upv.es/index.php/HEAD/HEAD18Bravo-Rivera, C.; Díaz-Ríos, M.; Aldarondo-Hernández, A.; Santos-Vera, B.; Ramos-Medina, L.; De Jesús-Burgos, M.; Bravo-Rivera, H.... (2018). NeuroBoricuas: a novel approach for incorporating neuroscience education in schools of Puerto Rico. Editorial Universitat Politècnica de València. 1447-1455. https://doi.org/10.4995/HEAD18.2018.8223OCS1447145

School coexistence and conflict resolution mediated by information and communication technology

Colombia es un país que se está preparando para la paz, sin embargo, en las instituciones educativas se encuentran altos índices de conflictos, por lo cual es imperante emplear estrategias educativas que fomenten una sana convivencia. El articulo tiene como objetivo presentar estrategias pedagógicas para fortalecer la convivencia escolar y solución de conflictos, mediante el uso de tecnologías de la información y la comunicación. El estudio es de tipo cualitativo bajo el modelo de investigación acción. Se evidenciaron manifestaciones violentas y comportamientos erráticos por parte de los estudiantes en la interacción con su grupo de pares, donde se demuestran agresiones verbales, físicas, discriminación, lenguaje soez, ruptura de normas escolares e irrespeto a la autoridad, la cual es representada por docentes y cuerpo administrativo de la institución, donde a través de las TIC se crearon espacios de participación que permitieron generar una mejor convivencia escolar basada en la solución de conflictos.Colombia is a country that is preparing for peace, however, in educational institutions are high rates of conflict, which is why it is imperative to use educational strategies that promote a healthy coexistence. The aim of the article is to present pedagogical strategies to strengthen school coexistence and conflict resolution, through the use of information and communication technologies. The study is of qualitative type under the action research model. There were violent demonstrations and erratic behavior by students in the interaction with their peer group, where verbal, physical aggressions, discrimination, foul language, breaking of school rules and disrespect to the authority are shown, which is represented by teachers. and the administrative body of the institution, where through TIC spaces of participation were created that allowed generating a better school coexistence based on the solution of conflicts

Degradation aspects of water formation and transport in Proton Exchange Membrane Fuel Cell: A review

This review paper summarises the key aspects of Proton Exchange Membrane Fuel Cell (PEMFC) degradation that are associated with water formation, retention, accumulation, and transport mechanisms within the cell. Issues related to loss of active surface area of the catalyst, ionomer dissolution, membrane swelling, ice formation, corrosion, and contamination are also addressed and discussed. The impact of each of these water mechanisms on cell performance and durability was found to be different and to vary according to the design of the cell and its operating conditions. For example, the presence of liquid water within Membrane Electrode Assembly (MEA), as a result of water accumulation, can be detrimental if the operating temperature of the cell drops to sub-freezing. The volume expansion of liquid water due to ice formation can damage the morphology of different parts of the cell and may shorten its life-time. This can be more serious, for example, during the water transport mechanism where migration of Pt particles from the catalyst may take place after detachment from the carbon support. Furthermore, the effect of transport mechanism could be augmented if humid reactant gases containing impurities poison the membrane, leading to the same outcome as water retention or accumulation. Overall, the impact of water mechanisms can be classified as aging or catastrophic. Aging has a long-term impact over the duration of the PEMFC life-time whereas in the catastrophic mechanism the impact is immediate. The conversion of cell residual water into ice at sub-freezing temperatures by the water retention/ accumulation mechanism and the access of poisoning contaminants through the water transport mechanism are considered to fall into the catastrophic category. The effect of water mechanisms on PEMFC degradation can be reduced or even eliminated by (a) using advanced materials for improving the electrical, chemical and mechanical stability of the cell components against deterioration, and (b) implementing effective strategies for water management in the cell

Tamoxifen-Mediated Recovery after Spinal Cord Injury Is Sex and Time Dependent

Despite the advancement of pharmaceutical and biomechanical therapeutic interventions, spinal cord injury (SCI) remains a disease without a cure. The cellular-molecular footprint of SCI suggests that the trauma is a multi-factorial event; one that requires a multi-active intervention to improve outcome. The pathophysiology of SCI begins immediately and extends for months. It is carried out by signaling mechanisms in central nervous system (CNS) cells (neuronal, astroglial, oligodendroglial and microglial) and by cells that infiltrate the CNS after blood-brain barrier rupture. The signaling events between the multiple cells continue through time, creating a non-permissive environment for neuronal survival and impeding sensory and motor recovery after SCI. The progression of the initial lesion into rostro-caudal penumbras alters neuro-glial homeostasis, leading to neurotransmitter imbalances, activation of aberrant sprouting processes, axonal and neuronal degeneration affecting the transmission of tactile and noxious stimulus. In addition to the loss of motor function, approximately 60% of SCI patients suffer from neuropathic pain, a process caused mostly by the spontaneous activation of spinothalamic neurons leading to pain transmission. Previous findings suggest biological sex influences the outcome after SCI (females recover better than males). Estrogen receptors (ERs) activation exert neuroprotection after CNS trauma, but the long-term use of estrogenic hormones should be managed carefully due to the excessive trophic activity (among others). Tamoxifen (TAM), a selective estrogen receptor modulator, may be used to activate ERs and exploit their neuro and glio-protective activity. Patients often arrive at the clinic hours after the trauma, suggesting that therapeutic interventions should evaluate the therapeutic window after SCI. A gap of knowledge exists on the time-dependent nature of SCI as a multi-factorial event that biological sex differences affect the outcome and the effects of therapy delay in male and female. The objective of this study was to investigate the spatio-temporal mechanisms activated by TAM (associated to neuronal, astroglial and oligodendrocytes), the therapeutic window available to administer treatment and the effects of biological sex on locomotor recovery and allodynia after SCI. The general hypothesis of this study is that TAM will exert neuro and glio-protection by reducing secondary damage, favoring locomotor recovery and reducing pain development after SCI in a clinically-relevant therapeutic window. To test this, we used the MACSIS impactor to exert a moderate contusion to male and female rats, followed by TAM administration immediately or in a window of 6, 12 or 24 hrs after SCI. The animals were sacrificed at 2, 7, 14, 28 and 35 days post-injury (DPI) to study mechanisms of secondary damage. We studied the cellular mechanisms by Western blot, immunofluorescence, and histology. Locomotor recovery was evaluated weekly, until 35 DPI while allodynia development was evaluated during the chronic stages (21–35 DPI). Our results demonstrate that TAM exerts sex and time-dependent effects after SCI. Spatio-temporal response mechanisms were similar between male and female rats (TAM reduced chronic astrogliosis, increased white matter spared tissue and increased neuronal survival). Female rats exhibited a therapeutic window of 24 hrs, while male exhibited a reduced window of 6 hrs. TAM reduced mechanical allodynia at 28 DPI in female rats, and this response was sex-specific. The glutamate transporters EAAT-1 and EAAT-2 were differentially expressed in male and female rats with no significant changes after SCI or upon TAM treatment. Female (sham or SCI) showed significantly higher levels of EAAT-1 while male (sham or SCI) showed significantly higher levels of EAAT-2 when compared to female. The observed behavioral (allodynia) response was not related to changes in glutamatergic transporters (EAAT-1 or EAAT-2) expression or alterations in peptidergic/non-peptidergic fiber sprouting into deeper laminae (IB4 and cGRP-α immunoreactivity). These findings suggest a potential role of TAM as a therapeutic intervention after SCI due to its neuroprotective and glio-protective effects favoring locomotor recovery in a clinically relevant window, without enhancing allodynia development after SCI

Performance studies of bare and Co-plated titanium alloy as cathode current collector in Molten Carbonate Fuel Cell (MCFC)

Abstract The corrosion characteristics of bare, heat treated and cobalt coated titanium alloys were studied and compared with that of SS 316 in molten carbonates (Li/K = 62/38 vol.%) at 650°C under oxygen atmosphere using electrochemical and surface characterization techniques. Immersion test of titanium alloys conducted in cathode environment followed by atomic absorption spectroscopy (AAS) indicated leaching of molybdenum from the alloy. Coating the alloy with Co was found to decrease the molybdenum dissolution rate. X-ray diffraction results showed the formation of LiTiO 2 and Li 2 TiO 3 on the surface of the titanium alloys and formation of LiFeO 2 and Fe 2 O 3 in the case of SS 316. SEM and EDAX analysis of the post-test samples revealed the loss of Mo, Sn and Zr from the titanium alloys and loss of Cr and Ni from SS 316. Electrochemical studies showed that the conductivity of the corrosion scale was higher for cobalt electroplated alloy when compared to other titanium alloys and lower than that of SS 316. Cobalt coated titanium alloy exhibited higher polarization resistance than other alloys. The present study confirmed that the surface modification of titanium alloy lead to the formation of a protective layer with better corrosion barrier properties and better electronic conductivity in molten carbonate fuel cell cathode operating conditions

Catalyst evaluation for a sulfur dioxide-depolarized electrolyzer

Thermochemical processes are being developed to provide global-scale quantities of hydrogen. A variant on sulfur-based thermochemical cycles is the hybrid sulfur (HyS) process which uses a sulfur dioxide-depolarized electrolyzer (SDE) to produce the hydrogen. Testing examined the activity and stability of platinum and palladium as the electrocatalyst for the SDE in highly concentrated sulfuric acid solutions. Cyclic and linear sweep voltammetry revealed that platinum provided better catalytic activity with much lower potentials and higher currents than palladium. Testing also showed that the catalyst activity is strongly influenced by the concentration of the sulfuric acid electrolyte. Keywords: Hydrogen, Platinum, Palladium, Sulfuric acid, Thermochemica