An efficient composite membrane to improve the performance of PEM reversible fuel cells

The aim of this study is to develop composite Nafion/GO membranes, varying GO loading, to be used in a Unitized reversible fuel cell comparing its performance with the baseline Nafion. Water uptake, ion exchange capacity (IEC), tensile strength, and SEM (scanning electron microscope) analysis are discussed. The SEM analysis revealed how the GO is homogeneously disposed into the Nafion matrix. The addition of GO improves the membrane tensile strength while reducing the elongation ratio. Water uptake, IEC enhance with the increasing of GO content. Regarding fuel cell mode, the performance is analysed using a polarization curve on a MEA with an effective area of 9 cm2. The composite membrane demonstrated higher mechanical strength, enhanced water uptake so higher performance in fuel cell mode. Despite the power absorbed from the electrolysis is higher when using a composite membrane, the beneficial effect in FC mode resulted in a slightly higher round trip efficiency. The GO-Nafion membrane was not able to maintain its performance with increasing the operating time, so potentially leading to a lower lifetime than the Nafion bare

transcriptional regulation of nuclear genes controlling plastid differentiation in tomato

ABSTRACTSeveral mechanisms which control transcription of genes encoding plastidial proteins in tomato are overviewed: light, the circadian clock, photooxidative stress and tissue-specific factors. Protein factors binding promoters of genes responding to such stimuli are described, as well as their abundance during the various phases of the light-dark cycle. Finally, the structure and regulation of a novel class of genes encoding plastidial enzymes, controlling carotenoid biosynthesis, are describe

Characterization of marble weathering through pore structure quantitative analysis

Y Stone weathering is strongly controlled by the intrinsic properties of the stone and by its use. Previous studies demonstrate that the response to natural or artificial ageing processes of the rocks seems to be strongly influenced by the pore structure of the stone. A better understanding of this phenomenon is provided by the study and characterization of porosity and of the pore structure at different degrees of alteration. The analysis of the evolution of the decay leads to the evaluation of the durability of marble in facades, and more generally in buildings, as well as for the protection and recovery of artistic and architectural heritage.In this paper, we apply a methodology for the geometrical characterization of the pore structure to quantify alteration induced by natural weathering on marble slabs. The approach is based on the application of a path-finding algorithm to 2D binary images representative of thin sections of marble at different degrees of alteration. Through the identification of the paths within the porous domain, the methodology allows the characterization of the pore structure in terms of pore radius distribution along the identified paths. Analysis of the results demonstrate a good agreement between the degree of alteration of the pore structure and the corresponding variation of the physical and mechanical properties of the rock samples under investigation

States of 15C via the (18O,16O) reaction

A study of the 15C states was pursued in 2008 at the Catania INFN-LNS laboratory by the 13C(18O,16O)15C reaction at 84 MeV incident energy. The 16O ejectiles were detected at forward angles by the MAGNEX magnetic spectrometer. Thanks to an innovative technique the ejectiles were identified without the need of time of flight measurements. Exploiting the large momentum acceptance (25%) and solid angle (50 msr) of the spectrometer, the 15C energy spectra were obtained with a quite relevant yield up to about 20 MeV excitation energy. The application of the powerful technique of the trajectory reconstruction did allow to get an energy resolution of about 250 keV FWHM, limited mainly by straggling effects. The spectra show several known low lying states up to about 7 MeV excitation energy as well as two unknown resonant structures at about 11.4 and 13.5 MeV. The strong excitation of these latter together with the measured width of about 2 MeV FWHM could indicate the presence of collective modes of excitation connected to the transfer of a correlated neutron pair

Investigation of α-cluster states in 13C via the (6Li,d) reaction

The 9Be(6Li,d)13C reaction was used to investigate possible α-cluster states in 13C. The reaction was measured at 25.5 MeV incident energy, employing the São Paulo Pelletron-Enge-Spectrograph facility and the nuclear emulsion detection technique. Ten out of sixteen known levels of 13C, up to 11 MeV of excitation, were observed and, due to the much improved energy resolution of 50 keV, at least three doublets could be resolved. This work presents a preliminary analysis of five of the most intensely populated states, also in comparison with the results of former transfer studies

How underground systems can contribute to meet the challenges of energy transition

The paper provides an overview of the several scientific and technical issues and challenges to be addressed for underground storage of carbon dioxide, hydrogen and mixtures of hydrogen and natural gas. The experience gained on underground energy systems and materials is complemented by new competences to adequately respond to the new needs raised by transition from fossil fuels to renewables. The experimental characterization and modeling of geological formations (including geochemical and microbiological issues), fluids and fluid-flow behavior and mutual interactions of all the systems components at the thermodynamic conditions typical of underground systems as well as the assessment and monitoring of safety conditions of surface facilities and infrastructures require a deeply integrated teamwork and fit-for-purpose laboratories to support theoretical research. The group dealing with large-scale underground energy storage systems of Politecnico di Torino has joined forces with the researchers of the Center for Sustainable Future Technologies of the Italian Institute of Technology, also based in Torino, to meet these new challenges of the energy transition era, and evidence of the ongoing investigations is provided in this paper

A Novel Role for Dbx1-Derived Cajal-Retzius Cells in Early Regionalization of the Cerebral Cortical Neuroepithelium

Patterning of the cerebral cortex during embryogenesis depends not only on passive diffusion of morphogens but also on signal delivery by Cajal-Retzius neurons that migrate over long distances