2,507 research outputs found
Computational modelling as a design tool for bioelectrochemical systems
Get PDFDesign of bioelectrochemical systems (BESs) needs to consider complex biological, physicochemical, and electrochemical phenomena, as well as aspects related to mass, charge and momentum transfer. Experimental optimisation of such complex systems will be too expensive in terms of time and cost, so that a model-based approach is a necessary route in BES design. In this work, the relevance of modelling in the literature on BESs is quantitatively assessed, and the main pros and cons of the different models of BES are identified. Among the different models, computational bioelectrochemical models (CBMs) are the most promising, the main potential and drawbacks of CBMs are then discussed, and the issues open for future research are indicated
Mechanistic insights into 2,4-D photoelectrocatalytic removal from water with TiO2 nanotubes under dark and solar light irradiation
Get PDFRemoval of recalcitrant pollutants from water is a major challenge, to which the photoelectrocatalytic processes may be a solution. Applied potential plays a key role in the photocatalytic activity of the semiconductor. This paper investigated the effect of applied potential on the photoelectrocatalytic oxidation of 2,4-Dichlorophenoxyacetic acid (2,4-D) with TiO2 nanotubular anodes under solar light irradiation. The process was investigated at constant potentials in different regions of the polarization curve: the ohmic region, the saturation region and in the region of the Schottky barrier breakdown. PEC tests were performed in aqueous solutions of 2,4-D, and in the presence of methanol or formic acid, as scavengers of OH• radicals and holes. Results showed the main mechanism is oxidation by OH• radicals from water oxidation, while runs with hole scavenger revealed a second mechanism of direct oxidation by holes photogenerated at the electrode surface, with high removal rates due to current doubling effect
Anion exchange membrane: A valuable perspective in emerging technologies of low temperature water electrolysis
Get PDFWhen powered by renewable energy source, efficient and low-cost water electrolysis may be a sustainable way to produce green H2, making it competitive with respect to grey H2 from fossil fuels. In the present article, the urgency of improving the efficiency of the water electrolysis process has been highlighted, analyzing the recent progress in the scientific field. Anion Exchange Membrane Water Electrolysis (AEMWE) has been indicated as a new generation technique where the advantages of Alkaline (AWE) and Proton Exchange Membrane (PEM) Water Electrolysis (WE) could be joined. The combination of bibliometric and bibliographic analyses has been used to evaluate the temporal evolution of the research, and to identify the topics of recent investigation, and possible future developments
Modelling and EIS characterization of a tubular microbial fuel cell with slip-casted ceramic membrane
Get PDFA 3D mathematical model has been applied to a tubular MFC with ceramic separators that were fabricated by slip-casting. The system features a carbon felt anode and a carbon-based cathode with a mixture of activated carbon and carbon black as catalyst. Electricity generation and substrate removal were first experimentally investigated with the cell operating in fed-batch mode. The cell was also characterised using polarisation experiments and electrochemical impedance spectroscopies (EIS). Experimental results were used to calibrate the model and obtain the kinetics parameters for biofilm formation, as well as bioelectrochemical and electrochemical reactions. The model has been solved to represent the system under the conditions used in the experiments with a good fitting of the data. The evolution of biofilm thickness and profile of concentration of substrate with time calculated with the model are presented and discussed. The model was also used to simulate different scenarios and has been proven to be a versatile tool for designing and optimising the investigated system
Electrochemical synthesis of polyaniline/metal-based anodes and their use in microbial fuel cell
Get PDFA limited number of metals may be suitable as bioanode material: noble metals, such as gold and platinum, could be the optimum choice being electrochemically inert in the operational potential window of the bioelectrochemical system. However, high costs limit their wide scale application. Even though its antimicrobial nature, copper is being considered as a promising alternative anode material, due to its high conductivity, that allows minimising the electrode material costs. Literature research indicated that high-performing electrochemically active biofilms may be grown on this metal. In the present work, gold and copper substrates have been coated by a conductive polymer (PANI), using a layer – by – layer procedure: surface grafting by reduction of 4-nitrobenzendiazonium salt was followed by reduction of nitro- to amino-groups; PANI was electrodeposited on this under-layer. The synthesized anodes were tested as working electrodes (WE) in a microbial fuel cell fed with anaerobic sludge and acetate; to assess the growth of the biofilm on the WE surface, the trend of the bioelectrocatalytic current of acetate oxidation was monitored over time. Cyclic voltammetries reveal the presence of typical redox couples related to the presence of electroactive microorganisms on the electrode surface. Preliminary data show bioelectrochemical activity on polyaniline-coated metal surfaces
Simple and precise approach for determination of Ohmic contribution of diaphragms in alkaline water electrolysis
Get PDFA simple and low-cost alternating current (AC)-based method, without electrolyte correction, is proposed (Electrochemical Impedance Spectroscopy (EIS)-Zero Gap Cell) for the determination of ohmic contribution of diaphragms. The effectiveness of the proposed methodology was evaluated by using a commercial Alkaline Water Electrolysis (AWE) diaphragm (Zirfon®). Furthermore, the results were compared with two conventional electrochemical methodologies for calculating the separator resistance, based on direct current (DC), and AC measurements, respectively. Compared with the previous techniques, the proposed approach reported more accurate and precise values of resistance for new and aged samples. Compared with the manufacturer reference, the obtained error values for new samples were 0.33%, 5.64%, and 41.7%, respectively for EIS-Zero gap cell, AC and DC methods, confirming the validity and convenience of the proposed technique
Transvaginal ultrasound (TVS) versus Magnetic Resonance (MR) for diagnosing deep infiltrating endometriosis: a systematic review and meta-analysis
Get PDFObjective: To perform a systematic review of studies comparing the accuracy of transvaginal ultrasound (TVS) and magnetic resonance imaging (MRI) in diagnosing deep infiltrating endometriosis (DIE) including only studies in which patients underwent both techniques. Methods: An extensive search was carried out in PubMed/MEDLINE and Web of Science for papers from January 1989 to October 2016 comparing TVS and MRI in DIE. Studies were considered eligible for inclusion if they reported on the use of TVS and MRI in the same set of patients for the preoperative detection of endometriosis in pelvic locations in women with clinical suspicion of DIE and using surgical data as a reference standard. Quality was assessed using the QUADAS-2 tool. A random-effects model was used to determine pooled sensitivity, specificity, positive and negative likelihood ratios (LR+ and LR–) and diagnostic odds ratio (DOR). Results: Of 375 citations identified, six studies (n = 424) were considered eligible. For MRI in the detection of DIE in the rectosigmoid, pooled sensitivity was 0.85 (95% CI, 0.78–0.90), specificity was 0.95 (95% CI, 0.83–0.99), LR+ was 18.4 (95% CI, 4.7–72.4), LR– was 0.16 (95% CI, 0.11–0.24) and DOR was 116 (95% CI, 23–585). For TVS in the detection of DIE in the rectosigmoid, pooled sensitivity was 0.85 (95% CI, 0.68–0.94), specificity was 0.96 (95% CI, 0.85–0.99), LR+ was 20.4 (95% CI, 4.7–88.5), LR– was 0.16 (95% CI, 0.07–0.38) and DOR was 127 (95% CI, 14–1126). For MRI in the detection of DIE in the rectovaginal septum, pooled sensitivity was 0.66 (95% CI, 0.51–0.79), specificity was 0.97 (95% CI, 0.89–0.99), LR+ was 22.5 (95% CI, 6.7–76.2), LR– was 0.38 (95% CI, 0.23–0.52) and DOR was 65 (95% CI, 21–204). For TVS in the detection of DIE in the rectovaginal septum, pooled sensitivity was 0.59 (95% CI, 0.26–0.86), specificity was 0.97 (95% CI, 0.94–0.99), LR+ was 23.5 (95% CI, 9.1–60.5), LR– was 0.42 (95% CI, 0.18–0.97) and DOR was 56 (95% CI, 11–275). For MRI in the detection of DIE in the uterosacral ligaments, pooled sensitivity was 0.70 (95% CI, 0.55–0.82), specificity was 0.93 (95% CI, 0.87–0.97), LR+ was 10.4 (95% CI, 5.1–21.2), LR– was 0.32 (95% CI, 0.20–0.51) and DOR was 32 (95% CI, 12–85). For TVS in the detection of DIE in the uterosacral ligaments, pooled sensitivity was 0.67 (95% CI, 0.55–0.77), specificity was 0.86 (95% CI, 0.73–0.93), LR+ was 4.8 (95% CI, 2.6–9.0), LR– was 0.38 (95% CI, 0.29–0.50) and DOR was 12 (95% CI, 7–24). Confidence intervals of pooled sensitivities, specificities and DOR were wide for both techniques in all the locations considered. Heterogeneity was moderate or high for sensitivity and specificity for both TVS and MRI in most locations assessed. According to QUADAS-2, the quality of the included studies was considered good for most domains. Conclusion: The diagnostic performance of TVS and MRI is similar for detecting DIE involving rectosigmoid, uterosacral ligaments and rectovaginal septum
OC15.07: Ultrasonographic “soft” markers for the detection of rectosigmoid endometriosis
No full textAnion exchange membrane: A valuable perspective in emerging technologies of low temperature water electrolysis
No full text[EN] When powered by renewable energy source, efficient and low-cost water electrolysis may be a sustainable way to produce green H2, making it competitive with respect to grey H2 from fossil fuels. In the present article, the urgency of improving the efficiency of the water electrolysis process has been highlighted, analyzing the recent progress in the scientific field. Anion Exchange Membrane Water Electrolysis (AEMWE) has been indicated as a new generation technique where the advantages of Alkaline (AWE) and Proton Exchange Membrane (PEM) Water Electrolysis (WE) could be joined. The combination of bibliometric and bibliographic analyses has been used to evaluate the temporal evolution of the research, and to identify the topics of recent investigation, and possible future developments.Palmas, S.;Rodriguez, J.;Mais, L.;Mascia, M.;Cifre-Herrando, Mireia;Vacca, A. (2023). Anion exchange membrane: A valuable perspective in emerging technologies of low temperature water electrolysis. Current Opinion in Electrochemistry. 37. https://doi.org/10.1016/j.coelec.2022.101178S3
Práticas de produção mais limpa num fabricante de eletrodomésticos do setor de linha branca: um estudo de caso
Get PDFDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-graduação em Engenharia de Produção, Florianópolis, 2013A Produção mais Limpa tem ganhado significativa atenção das Empresas de Manufatura como uma estratégia pró-ativa em relação à gestão de meio ambiente, possibilitando a geração de benefícios tanto ambientais como econômicos. No entanto, ainda são escassas as publicações no setor que desempenha um papel importante no cenário econômico nacional, o Setor de Eletrodomésticos de Linha Branca. Nesse contexto, o presente trabalho objetiva analisar as principais práticas de Produção Mais Limpa (P+L) nos processos produtivos de um fabricante do setor de eletrodomésticos de linha branca, mais especificamente no desenvolvimento de novos processos de fabricação de refrigeradores e na gestão dos processos fabris atuais. Por meio da aplicação de uma survey de avaliação do nível de absorção da produção mais limpa na empresa estudada, observou-se que a empresa em questão apresenta um engajamento significativo com a P+L, entretanto, há grandes oportunidade de implantação de projetos de P+L com a redução de barreiras organizacionais que dificultam a realização de novas implementações. Através da criação de um protocolo de identificação de práticas de Produção mais Limpa e da análise detalhada destas, o trabalho consolidou uma lista de práticas que pode ser uma referência para o setor, tais como a substituição de antigas linhas de pintura, o reaproveitamento da água de estação de tratamento de efluentes, a mudança no tratamento de chapas metálicas, entre outros. Com enfoque na melhoria do nível de implementação da Produção mais Limpa na empresa em questão, uma lista de barreiras foi capturada e comparada com a literatura existente, servindo de referência para o setor e para trabalhos futuros. Por fim, como recomendação de futuros estudos, sugere-se a Avaliação do Nível de Absorção da Produção mais Limpa em outras organizações do mesmo setor, possibilitando o estabalecimento de um panorama da P+L na industria nacional de Eletrodomésticos de Linha Branca. Abstract: The Cleaner Production has gained significant attention of Manufacturing Enterprises as a proactive strategy for the management of the environment, allowing the generation of both environmental and economic benefits. However, there are insufficient publications in the sector that plays an important role in national economic scenario, the Sector of Household Appliances. In this context, this paper aims to analyze the main practices of Cleaner Production (CP) in the production processes of a manufacturer in the industry of white goods, more specifically in the development of new manufacturing processes and management of current manufacturing processes of refrigerators. Through the application of a survey to assess the level of uptake of cleaner production in the company studied, it was observed that the company in question has a meaningful engagement with the CP, however, there is great opportunity to implement Cleaner Production projects with the reduction of organizational barriers that hinder the realization of new implementations. By creating a protocol for identifying cleaner production practices and detailed analysis of these, this work has consolidated a list of practices that can be a reference for the sector, such as the replacement of old paint lines, the water reuse treatment plant effluent, the change in the treatment of metal plates, among others. With a focus on improving the level of implementation of Cleaner Production in the company in question, a list of barriers was captured and compared with the existing literature, serving as a reference for the sector and for future work. Finally, as a recommendation for future studies, we suggest the evaluation of Cleaner Production uptake in other organizations in the same sector, allowing to obtain an overview of the CP in the National Industry of Household Appliances
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