Upgrading biogas with novel composite carbon molecular sieve (CCMS) membranes: Experimental and techno-economic assessment

The use of biogas as feedstock for hydrogen production was widely proposed in the literature in the last years as a strategy to reduce anthropogenic carbon emissions. However, its lower heating value compared to natural gas hampers the revamping of existing reforming plants. The use of composite carbon molecular sieve membranes for biogas upgrading (CO2 removal from biogas) was investigated experimentally in this work. In particular, ideal perm-selectivities and permeabilities above the Robeson plot for CO2/CH4 mixtures have been obtained. These membranes show better performances compared to polymeric membranes, which are nowadays commercialized for CO2 separation in natural gas streams. Compared to polymeric membranes, carbon membranes do not show deactivation by plasticization when exposed to CO2, and thus can find industrial application. This work was extended with a techno-economic analysis where carbon membranes are installed in a steam methane reforming plant. Results have been first validated with data from literature and show that the use of biogas increases the costs of hydrogen production to a value of 0.25 €/Nm3 compared to the benchmark technology (0.21 €/Nm3). On the other hand, the use of biogas leads to a decrease in carbon emissions up to 95%, thus the use of biogas for hydrogen production is foreseen as a very interesting alternative to conventional technologies in view of the reduction in the carbon footprint in the novel technologies that are to be installed in the near future

Auditory opportunity and visual constraint enabled the evolution of echolocation in bats

Substantial evidence now supports the hypothesis that the common ancestor of bats was nocturnal and capable of both powered flight and laryngeal echolocation. This scenario entails a parallel sensory and biomechanical transition from a nonvolant, vision-reliant mammal to one capable of sonar and flight. Here we consider anatomical constraints and opportunities that led to a sonar rather than vision-based solution. We show that bats' common ancestor had eyes too small to allow for successful aerial hawking of flying insects at night, but an auditory brain design sufficient to afford echolocation. Further, we find that among extant predatory bats (all of which use laryngeal echolocation), those with putatively less sophisticated biosonar have relatively larger eyes than do more sophisticated echolocators. We contend that signs of ancient trade-offs between vision and echolocation persist today, and that non-echolocating, phytophagous pteropodid bats may retain some of the necessary foundations for biosonar

Sub-cortical and brainstem sites associated with chemo-stimulated increases in ventilation in humans

We investigated the neural basis for spontaneous chemo-stimulated increases in ventilation in awake, healthy humans. Blood oxygen level dependent (BOLD) functional MRI was performed in nine healthy subjects using T2weighted echo planar imaging. Brain volumes (52 transverse slices, cortex to high spinal cord) were acquired every 3.9 s. The 30 min paradigm consisted of six, 5-min cycles, each cycle comprising 45 s of hypoxic-isocapnia, 45 s of isooxic-hypercapnia and 45 s of hypoxic-hypercapnia, with 55 s of non-stimulatory hyperoxic-isocapnia (control) separating each stimulus period. Ventilation was significantly (p < 0.001) increased during hypoxic-isocapnia, isooxic-hypercapnia and hypoxic-hypercapnia (17.0, 13.8, 24.9 L/min respectively) vs. control (8.4 L/min) and was associated with significant (p < 0.05, corrected for multiple comparisons) signal increases within a bilateral network that included the basal ganglia, thalamus, red nucleus, cerebellum, parietal cortex, cingulate and superior mid pons. The neuroanatomical structures identified provide evidence for the spontaneous control of breathing to be mediated by higher brain centres, as well as respiratory nuclei in the brainstem

Advances and Perspectives of H2 Production from NH3 Decomposition in Membrane Reactors

Hydrogen is often regarded as an ideal energy carrier. Its use in energy conversion devices does in fact not produce any pollutants. However, due to challenges related to its transportation and storage, liquid hydrogen carriers are being investigated. Among the liquid hydrogen carriers, ammonia is considered very promising because it is easy to store and transport, and its conversion to hydrogen has only nitrogen as a byproduct. This work focuses on a review of the latest results of studies dealing with ammonia decomposition for hydrogen production. After a general introduction to the topic, this review specifically focuses on works presenting results of membrane reactors for ammonia decomposition, particularly describing the different reactor configurations and operating conditions, membrane properties, catalysts, and purification steps that are required to achieve pure hydrogen for fuel cell applications

Carbon Molecular Sieve Membrane Reactors for Ammonia Cracking

The utilization of ammonia for hydrogen storage relies on the implementation of efficient decomposition techniques, and the membrane reactor, which allows simultaneous ammonia decomposition and hydrogen recovery, can be regarded as a promising technology. While Pd-based membranes show the highest performance for hydrogen separation, their applicability for NH3-sensitive applications, such as proton exchange membrane (PEM) fuel cells, demands relatively thick, and therefore expensive, membranes to meet the purity targets for hydrogen. To address this challenge, this study proposes a solution involving the utilization of a downstream hydrogen purification unit to remove residual ammonia, thereby enabling the use of less selective, therefore more cost-effective, membranes. Specifically, a carbon molecular sieve membrane was prepared on a tubular porous alumina support and tested for ammonia decomposition in a membrane reaction setup. Operating at 5 bar and temperatures ranging from 450 to 500 °C, NH3 conversion rates exceeding 90% were achieved, with conversion approaching thermodynamic equilibrium at temperatures above 475 °C. Simultaneously, the carbon membrane facilitated the recovery of hydrogen from ammonia, yielding recoveries of 8.2–9.8%. While the hydrogen produced at the permeate side of the reactor failed to meet the purity requirements for PEM fuel cell applications, the implementation of a downstream hydrogen purification unit comprising a fixed bed of zeolite 13X enabled the production of fuel cell-grade hydrogen. Despite performance far from being comparable with the ones achieved in the literature with Pd-based membranes, this study underscores the viability of carbon membranes for fuel cell-grade hydrogen production, showcasing their competitiveness in the field

Modelling of metallic supported PdAg membranes with inter-diffusion barrier

Metallic supported palladium-based membranes require an additional inter-diffusion barrier between the metallic support and the palladium-based selective layer. This porous layer can also function as a smoothening layer to allow for the deposition of a thinner palladium-based layer. The disadvantage of adding this extra layer is that it increases the overall mass transfer resistance of the membrane. In this work, the (relative) resistance of this layer was determined by developing a multi-layer model for the metallic supported palladium-based membrane with inter-diffusion barrier. Permeation experiments and characterizations were performed before and after the deposition of the inter-diffusion barrier and PdAg layer. The experimental data was used to fit the critical parameters for the multi-layer permeation model. The resulting model could then be used to determine the pressure drop induced by each layer of the membrane. The results revealed that the thin PdAg layer causes more than 90% of the total mass transfer resistance of the membrane (100% H2, T = 400–500 °C and Δp = 3 bar). To mitigate the contribution of the selective layer on the overall mass transfer resistance of the membrane, implementing a strategy to enhance the membrane permeance is therefore required. This could in the first place be achieved by improving the selective layer deposition methodology, but also by reducing the thickness of the PdAg layer. However, accomplishing such a reduction has significant challenges when considering metallic supports

MaquiAR: uma solução com realidade aumentada aplicada no e-commerce de maquiagem

TCC(graduação) - Universidade Federal de Santa Catarina. Centro Tecnológico. Sistemas de Informação.Compras online estão cada vez mais populares, e receberam um impulso ainda maior com a pandemia da COVID-19. Assim, foram evidenciados tanto suas vantagens em relação ao comércio em lojas físicas, como a comodidade, quanto suas desvantagens. Uma delas é a impossibilidade de tocar o produto com as mãos. É difícil ter certeza quanto de como o produto é no mundo real já que a maior parte dos produtos são apresentados em fotos 2D e breve descrição. Com isso muitos consumidores acabam desistindo da compra ou se arrependendo dela porque o produto não era o esperado. O objetivo deste trabalho é desenvolver um aplicativo com Realidade Aumentada de maquiagem para dispositivos móveis, com o propósito de levar aos usuários uma experiência diferente na apresentação de maquiagem online e maior segurança para comprá-las. Para sustentar a proposta do aplicativo, foi estudado na literatura os impactos do uso de Realidade Aumentada na intenção de compra dos consumidores e foram analisados aplicativos populares relacionados ao comércio eletrônico de maquiagens. A proposta deste trabalho é um aplicativo Android que permitirá os usuários experimentarem diferentes tipos de maquiagem através da câmera do smartphone, por meio de filtros com Realidade Aumentada e terá acesso a informações das maquiagens que estão experimentando e de como comprá-las. É descrito o processo de desenvolvimento do aplicativo, a arquitetura utilizada e as dificuldades encontradas. Por fim, são apresentados testes realizados com usuários e os seus resultados.Online shopping is increasingly popular, and has received a boost with the COVID-19 pandemic. Thus, both its advantages in relation to shopping in physical stores, such as convenience, and its disadvantages were evidenced. One of the disadvantages is the impossibility to touch the product with your hands. It is hard to evaluate how the product looks in real world since most of the products are presented in 2D photos and a brief description. As a result, many consumers end up giving up on the purchase or regretting it because the product was not what they expected it to be. The goal of this work is to develop a makeup Augmented Reality application for mobile devices, with the purpose of bringing users a different experience in how makeup is presented online and greater security to buy them. To support this application's proposal, the impacts of the use of Augmented Reality on consumers' purchase intentions were studied in the literature and popular applications related to makeup e-commerce were analyzed. The proposal of this work is an Android application that will allow users to try different types of makeup through the smartphone's camera, through filters with Augmented Reality and the users will have access to information about the makeup they are trying and how to buy them. The application development process, the architecture used and the difficulties encountered are described. Finally, tests performed with users and their results are presented