6,560 research outputs found

    The Potential of Electrospinning to Enable the Realization of Energy-Autonomous Wearable Sensing Systems

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    The market for wearable electronic devices is experiencing significant growth and increasing potential for the future. Researchers worldwide are actively working to improve these devices, particularly in developing wearable electronics with balanced functionality and wearability for commercialization. Electrospinning, a technology that creates nano/microfiber-based membranes with high surface area, porosity, and favorable mechanical properties for human in vitro and in vivo applications using a broad range of materials, is proving to be a promising approach. Wearable electronic devices can use mechanical, thermal, evaporative and solar energy harvesting technologies to generate power for future energy needs, providing more options than traditional sources. This review offers a comprehensive analysis of how electrospinning technology can be used in energy-autonomous wearable wireless sensing systems. It provides an overview of the electrospinning technology, fundamental mechanisms, and applications in energy scavenging, human physiological signal sensing, energy storage, and antenna for data transmission. The review discusses combining wearable electronic technology and textile engineering to create superior wearable devices and increase future collaboration opportunities. Additionally, the challenges related to conducting appropriate testing for market-ready products using these devices are also discussed

    Microwave - Plasma based Thermal Treatment of Asphaltene - derived Carbon Fibres

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    Asphaltene-based carbon fibres have emerged as a significant and sustainable alternative to conventional Polyacrylonitrile (PAN)-based carbon fibres, owing to their abundant availability, aromatic nature, and high carbon content. This thesis investigates the utilization of asphaltenes, extracted from bitumen in Alberta oilsands, as a valuable precursor for the manufacturing of carbon fibres. The precursor employed in commercial carbon fibre manufacturing accounts for approximately 51% of the total production cost. The utilization of asphaltene as a precursor offers the potential for cost reduction in carbon fibre production. With this reduced cost, carbon fibres, renowned for their exceptional mechanical properties such as high stiffness, remarkable tensile strength, chemical resistance, and capacity to withstand higher temperatures, can find applications across wide range of industries. Moreover, this cost reduction also contributes to the economic viability of converting industrial waste into valuable products. Conventional post-treatment processes in carbon fibre manufacturing, such as furnace stabilization and carbonization, play a crucial role in the production process, demanding considerable time and energy resources. Post-treatment alone, comprising 38% of the overall cost of carbon fibre production, significantly impacts the economic aspects of the manufacturing process. In this thesis, asphaltenes derived from Alberta oilsands are pretreated with solvents such as pentane and toluene to remove coke residues. Later, these asphaltenes are transformed into fibres through the process of melt spinning using a twin-screw extruder. An innovative approach involving microwave plasma thermal treatment, replacing conventional post-treatment methods, specifically carbonization, is then applied to convert these fibres into carbon fibres. The study of microwave plasma behaviour and its corresponding temperatures is successfully conducted through the use of Multiphysics Finite Element Analysis (FEA). An experimental optimization study involving the thermal treatment of stabilized fibres under varying power levels and treatment durations using microwave plasma has been conducted. The study successfully implemented microwave plasma techniques to achieve carbonization of asphaltene fibres, resulting in an increase in carbon content and the development of a well-ordered crystalline structure. The Element analysis revealed the dynamic changes in elemental composition, showcasing the effectiveness of microwave plasma in achieving carbonization. X-ray diffraction patterns and Raman spectroscopy provided valuable insights into the structural evolution, highlighting the unique impact of microwave plasma treatment on the development of a layered graphite-like structure and higher graphitic content. However, it is essential to acknowledge limitations, such as the observed surface damage and reduced tensile strength in microwave-plasma treated fibres, emphasizing the need for further optimization of parameters to maximize the benefits of this innovative approach. Overall, this research contributes valuable insights to the field of carbon fibre manufacturing, paving the way for more sustainable and economically feasible production processes with the utilization of asphaltene-based precursors and microwave plasma techniques

    Development of highly selective composite polymeric membranes for Li+/Mg2+ separation

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    Associate Laboratory for Green Chemistry-LAQV, which is financed by Portuguese national funds from FCT/MCTES (UID/QUI/50006/2019). This work was also supported by "Programa Operacional Regional de Lisboa, na componente FEDER" and "Fundacao para a Ciencia e Tecnologia, I.P." through research project PTDC/EQU-EPQ/29579/2017. S. Pawlowski acknowledges Fundacao para a Ciencia e Tecnologia, I.P. for his contracts CEECIND/01617/2017 and CEECIND/00340/2018. iNOVA4Health UIDB/Multi/04462/2020, a program financially supported by Fundacao para a Ciencia e Tecnologia is acknowledged. Funding from INTERFACE Programme, through the Innovation, Technology and Circular Economy Fund (FITEC), is also gratefully acknowledged. The authors acknowledge Professor Vitor D. Alves, from Instituto Superior de Agronomia, Universidade de Lisboa, for the support to analysing mechanical properties.To meet the exponentially rising demand for lithium, it becomes vital to develop environmentally friendly processes for its recovery from brines, salt lakes and/or seawater. In this work, novel composite lithium transport selective polymeric membranes were developed to separate lithium and magnesium ions. Hydrogen manganese oxide (HMO) (at weight percentage from 0 to 25%), polystyrene sulfonate sodium salt (PSS–Na) and lithium triflate (LiCF3SO3) were added into the sulfonated polyethersulfone (SPES) matrix to prepare composite membranes. The developed membranes showed high mechanical stability and a homogeneous distribution of HMO. The most promising membrane, containing 20% (w/w) of HMO, showed an almost 13 times higher Li+ ionic conductivity (8.28 mS/cm) compared to the control composite membrane (without HMO) and an average ideal selectivity of 11.75 for the Li+/Mg2+ pair. The composite-20% membrane had the lowest intermolecular distance between the polymer chains (according to X-ray diffraction (XRD) analysis), the most flexible structure (lowest Tg) and showed the homogeneous dispersion of HMO (SEM images), which explains its highest Li+/Mg2+ selectivity among the tested membranes. The lithium ion transport performance and separation efficiency were investigated through diffusion dialysis experiments, under different operating conditions. A binary separation factor of 9.10 for Li+/Mg2+ and Li+ molar flux of 0.026 mol/(m2.h) was achieved without applying any external potential difference. When an external potential difference of 0.2 V was applied, the binary separation factor of Li+/Mg2+ pair was 5, while the Li+ molar flux increased almost 5 times. The obtained results provide the basis to design and develop composite lithium transport selective polymeric membranes, thus representing a promising step for future implementation of such membranes to recover lithium from saline streams.preprintauthorsversionpublishe

    Metabolites in fish and humans as a response to different food ingredients : a metabolomics approach

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    The main objective of this thesis was to evaluate metabolomics changes in humans and fish as a response to food/feed consumption. To alleviate the environmental impact of animal production and maximize the use of resources, the valorization of meat by-products might be an attractive alternative. A meat product containing heart and aorta tissue from pork was designed and analyzed for fatty acid and metabolite composition. In comparison with a control of similar qualities, the designed meat product (or test product) showed higher monounsaturated fatty acid and tyramine levels and lower levels of sugars. The test meat product was used in a randomized controlled clinical trial to test for potential health effects in patients showing atherosclerosis symptoms. Patients receiving the test product showed a decrease in blood levels of low-density lipoproteins, total cholesterol, atherogenic index and triacylglycerols. To reduce the impact of animal production on ecosystems, the replacement of feed ingredients by a microbial alternative was realized. In this study, vegetable oils included in the feed of Arctic char (Salvelinus alpinus) were replaced by biomass of the oleaginous yeast (Rhodotorula toruloides). The analysis of the yeast biomass showed safe levels of pollutants and heavy metals. Fish growth and muscle fatty acid profile were similar to the control. A higher liver weight and hepatosomatic index were observed in fish fed including the yeast biomass, albeit no significant difference in liver fat content or in hepatic enzyme activity was observed. Quantification of plasma metabolites revealed higher levels of metabolites involved in energy pathways such as one-carbon metabolism and gluconeogenesis.In conclusion, this thesis showed that metabolomics can be applied to evaluate effects of food/feed at the molecular level in complex systems. It adds knowledge on the effects of meat by-product consumption in the particular case of atherosclerosis symptoms. The fish feed trial showed the possibility of feed modification with a specific yeast

    Natural and Technological Hazards in Urban Areas

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    Natural hazard events and technological accidents are separate causes of environmental impacts. Natural hazards are physical phenomena active in geological times, whereas technological hazards result from actions or facilities created by humans. In our time, combined natural and man-made hazards have been induced. Overpopulation and urban development in areas prone to natural hazards increase the impact of natural disasters worldwide. Additionally, urban areas are frequently characterized by intense industrial activity and rapid, poorly planned growth that threatens the environment and degrades the quality of life. Therefore, proper urban planning is crucial to minimize fatalities and reduce the environmental and economic impacts that accompany both natural and technological hazardous events

    Favorable Preclinical Pharmacological Profile of a Novel Antimalarial Pyrrolizidinylmethyl Derivative of 4-amino-7-chloroquinoline with Potent In Vitro and In Vivo Activities

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    The 4-aminoquinoline drugs, such as chloroquine (CQ), amodiaquine or piperaquine, are still commonly used for malaria treatment, either alone (CQ) or in combination with artemisinin derivatives. We previously described the excellent in vitro activity of a novel pyrrolizidinylmethyl derivative of 4-amino-7-chloroquinoline, named MG3, against P. falciparum drug-resistant parasites. Here, we report the optimized and safer synthesis of MG3, now suitable for a scale-up, and its additional in vitro and in vivo characterization. MG3 is active against a panel of P. vivax and P. falciparum field isolates, either alone or in combination with artemisinin derivatives. In vivo MG3 is orally active in the P. berghei, P. chabaudi, and P. yoelii models of rodent malaria with efficacy comparable, or better, than that of CQ and of other quinolines under development. The in vivo and in vitro ADME-Tox studies indicate that MG3 possesses a very good pre-clinical developability profile associated with an excellent oral bioavailability, and low toxicity in non-formal preclinical studies on rats, dogs, and non-human primates (NHP). In conclusion, the pharmacological profile of MG3 is in line with those obtained with CQ or the other quinolines in use and seems to possess all the requirements for a developmental candidate

    Device for Measuring Propagation Delays with TDC7200 Circuit

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    Tato diplomová práce se zabývá návrhem, realizací a testováním zařízení pro měření časových událostí v řádu jednotek nanosekund. Cílem této práce je srovnat toto zařízení s automatizovaným testerem Eagle ETS364. Na začátku práce jsou popsány různé způsoby měření času. Dále se práce zabývá rozborem obvodu TDC7200, možnostmi komunikace, jeho nastavením a funkcemi. Následuje specifikace vytvářeného zařízení, na kterou navazují návrhy samotného schématu, použitých součástek a desky plošných spojů. Finální kapitola se zabývá testováním navrhovaného zařízení, ověřením funkčnosti a srovnáním s možnostmi automatizovaného testeru.This diploma thesis is about design, implement and test of a device for measuring time events in order of nanoseconds. The goal of this thesis is to compare this device with automated tester Eagle ETS364. In the begining of this thesis are described different ways of measuring time. In the next chapter is study of TDC7200 circuit, description of communication, settings and capability of TDC7200. Then there is design of the actual schematics, used parts and printed circuit board. The last chapter is about testing, verifying functionality and comparsion with capibilities of automatized tester.430 - Katedra elektronikyvýborn
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