Preparation and characterization of yttria stabilized zirconia (YSZ) films deposited by dip-coating on LSM-YSZ substrate with different proportions

In this work, sol-gel/dip-coating process for obtaining yttria stabilized zirconia (YSZ, ZrO2–8% Y2O3) films deposited onto LSM-YSZ (lanthanum strontium manganite (LSM, La0.7Sr0.3MnO3) mixed with YSZ) with different proportions (20/80, 50/50, 80/20) was investigated. The films were deposited on substrate varying the number of layers deposited. LSM powders were obtained by the combustion method using metal nitrates and urea and YSZ was commercial. LSM-YSZ composite powders were obtained by the solid state method, through ball-milling of a mixture of LSM-YSZ (mass ratio) powder for 4 h with 500 rpm using ZrO2 balls as milling media. For LSMYSZ substrate a study of sintering temperature was performed, where the optimum sintering temperature for each LSM-YSZ studied proportion was obtained. According to our results, it was found that 1100 ºC is the optimum sintering temperature for 20/80, 950 ºC is the optimum sintering temperature for 50/50 and 900 ºC is the optimum sintering temperature for 80/20 because of the good phase formation. The films were characterized by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The films showed LSM, YSZ, SrZrO3 and La2O3 phases. Crack-free, homogeneous and well adhered films were obtained with a thickness between 3 and 38 μm. In this work, YSZ films with appropriate thickness were obtained for application as SOFC electrolyte

Current stage of development of GTL technology and perspectives for Brazil

Although the production of liquid fuels from coal, natural gas (CTL and GTL processes) and other carbon sources has been discovered 90 years ago, the interest was renewed in the last years motivated by stranded gas reserves and by petroleum market instability. This review intends to show the scenario of these technologies nowadays, discussing the applied technologies, the steps in an industrial plant, the ways to produce syngas and liquid fuels, the catalysts used, the type of reactors and the operating plants with their respective capacities, besides the technical, economical and environmental viability, challenges and perspectives for Brazil

Production and characterization of reduced graphene oxide films as transparent and conductive contacts

<p></p><p>ABSTRACT Dispersions of graphene oxide (GO) and reduced graphene oxide (rGO) were respectively chemically produced by the modified Hummers method and by reducing GO with the addition of PSS polymer (poly (4-styrenesulfonate sodium)) and ascorbic acid. Samples of GO and rGO/PSS were characterized by the following techniques: optical microscopy, scanning electron microscopy (SEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). From the dispersions thin films were deposited on glass substrates by the following methods: spray, dip coating and spin coating. The films produced were then thermally treated to improve adhesion on substrates and, specifically for GO films, for reduction, so as to form thermally reduced graphene oxide (trGO). The films were characterized as thickness, morphology, transmittance and sheet resistance. By means of the characterizations made from the dispersions it was possible to observe graphene sheets by optical microscopy, indicating the success of the production method employed; by means of the XPS, the composition of the samples of GO and rGO was determined and confirmed that the reduction with ascorbic acid was effective; the obtained transmittances were within the range indicated for application and the resistivities of some samples reached values close to that of materials traditionally applied as transparent films and conductors.</p><p></p

A new non-complex synthesis of NiO nanofoams for hydrogen storage applications

The use of nanofoams is beneficial for a wide range of applications ranging from catalysis to plasmonics. The present communication reports on the non-complex synthesis of NiO nanofoams and their use for hydrogen storage applications. The results point to an improved hydrogen storage capacity at room temperature and ambient pressure of hydrogen as compared to Ni-based systems in the literature. DFT calculations point to a quasi-molecular bonding of the H2 molecule at the surface of the NiO nanofoams. The results open new possibilities for the design of future smart materials for hydrogen storage applications and other fields

Brazilian Flora 2020: Leveraging the power of a collaborative scientific network

International audienceThe shortage of reliable primary taxonomic data limits the description of biological taxa and the understanding of biodiversity patterns and processes, complicating biogeographical, ecological, and evolutionary studies. This deficit creates a significant taxonomic impediment to biodiversity research and conservation planning. The taxonomic impediment and the biodiversity crisis are widely recognized, highlighting the urgent need for reliable taxonomic data. Over the past decade, numerous countries worldwide have devoted considerable effort to Target 1 of the Global Strategy for Plant Conservation (GSPC), which called for the preparation of a working list of all known plant species by 2010 and an online world Flora by 2020. Brazil is a megadiverse country, home to more of the world's known plant species than any other country. Despite that, Flora Brasiliensis, concluded in 1906, was the last comprehensive treatment of the Brazilian flora. The lack of accurate estimates of the number of species of algae, fungi, and plants occurring in Brazil contributes to the prevailing taxonomic impediment and delays progress towards the GSPC targets. Over the past 12 years, a legion of taxonomists motivated to meet Target 1 of the GSPC, worked together to gather and integrate knowledge on the algal, plant, and fungal diversity of Brazil. Overall, a team of about 980 taxonomists joined efforts in a highly collaborative project that used cybertaxonomy to prepare an updated Flora of Brazil, showing the power of scientific collaboration to reach ambitious goals. This paper presents an overview of the Brazilian Flora 2020 and provides taxonomic and spatial updates on the algae, fungi, and plants found in one of the world's most biodiverse countries. We further identify collection gaps and summarize future goals that extend beyond 2020. Our results show that Brazil is home to 46,975 native species of algae, fungi, and plants, of which 19,669 are endemic to the country. The data compiled to date suggests that the Atlantic Rainforest might be the most diverse Brazilian domain for all plant groups except gymnosperms, which are most diverse in the Amazon. However, scientific knowledge of Brazilian diversity is still unequally distributed, with the Atlantic Rainforest and the Cerrado being the most intensively sampled and studied biomes in the country. In times of “scientific reductionism”, with botanical and mycological sciences suffering pervasive depreciation in recent decades, the first online Flora of Brazil 2020 significantly enhanced the quality and quantity of taxonomic data available for algae, fungi, and plants from Brazil. This project also made all the information freely available online, providing a firm foundation for future research and for the management, conservation, and sustainable use of the Brazilian funga and flora