Search results for: J-V. Vignes

Authors: T. H. N. Nguyen, A. Khodan, M. Amamra, J-V. Vignes, A. Kanaev

Abstract:

The ultraporous nanofibrous alumina (NOA, Al2O3·nH2O) was synthesized by oxidation of laminated aluminium plates through a liquid mercury-silver layer in a humid atmosphere ~80% at 25°C. The material has an extremely high purity (99%), porosity (90%) and specific area (300 m2/g). The subsequent annealing of raw NOA permits obtaining pure transition phase (γ and θ) nanostructured materials. In this combination, we report on chemical, structural and phase transformations of pure and modified NOA by an impregnation of trimethylethoxysilane (TMES) and tetraethoxysilane (TEOS) during thermal annealing in the temperature range between 20 and 1650°C. The mass density, specific area, average diameter and specific area are analysed. The 3D model of pure NOA monoliths and silica modified NOA is proposed, which successfully describes the evolution of specific area, mass density and phase transformations. Activation energies of the mass transport in two regimes of surface diffusion and bulk sintering were obtained based on this model. We conclude about a common origin of modifications of the NOA morphology, chemical composition and phase transition.

Keywords: nanostructured materials, alumina (Al₂O₃), morphology, phase transitions

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Authors: Md. Maksudur Rahman Khan, Chee Wai Woon, Huei Ruey Ong, Vignes Rasiah, Chin Kui Cheng, Kar Min Chan, E. Baranitharan

Abstract:

The present work represents a preparation of non-precious iron-based electrocatalyst (FeN) for ORR in air-cathode microbial fuel cell by pyrolysis treatment. Iron oxalate which recovered from the industrial wastewater and Phenanthroline (Phen) were used as the iron and nitrogen precursors, respectively in preparing FeN catalyst. The performance of as prepared catalyst (FeN) was investigated in a single chambered air cathode MFC in which anaerobic sludge was used as inoculum and palm oil mill effluent as substrate. The maximum open circuit potential (OCV) and the highest power density recorded were 0.543 V and 4.9 mW/m2, respectively. Physical characterization of FeN was elucidated by using Brunauner Emmett Teller (BET), X-Ray Diffraction (XRD) analysis and Field Emission Scanning Electron Microscopy (FESEM) while the electrochemical properties were characterized by cyclic voltammetry (CV) analysis. The presence of biofilm on anode surface was examined using FESEM and confirmed using Infrared Spectroscopy and Thermogravimetric Analysis. The findings of this study demonstrated that FeN is electrochemically active and further modification is needed to increase the ORR catalytic activity.

Keywords: iron based catalyst, microbial fuel cells, oxygen reduction reaction, palm oil mill effluent

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Authors: Kurt Maxwell Kusterer, Sylvain Mignot, Annick Vignes

Abstract:

To our best knowledge YouTube is the largest video hosting platform in the world. A high number of creators, viewers, subscribers and commentators act in this specific eco-system which generates huge sums of money. Views, subscribers, and comments help to increase the popularity of content creators. The most popular creators are sponsored by brands and participate in marketing campaigns. For a few of them, this becomes a financially rewarding profession. This is made possible through the YouTube Partner Program, which shares revenue among creators based on their popularity. We believe that the role of comments in increasing the popularity is to be emphasized. In what follows, YouTube is considered as a bilateral network between the videos and the commentators. Analyzing a detailed data set focused on French YouTubers, we consider each comment as a link between a commentator and a video. Our research question asks what are the predominant features of a video which give it the highest probability to be commented on. Following on from this question, how can we use these features to predict the action of the agent in commenting one video instead of another, considering the characteristics of the commentators, videos, topics, channels, and recommendations. We expect to see that the videos of more popular channels generate higher viewer engagement and thus are more frequently commented. The interest lies in discovering features which have not classically been considered as markers for popularity on the platform. A quick view of our data set shows that 96% of the commentators comment only once on a certain video. Thus, we study a non-weighted bipartite network between commentators and videos built on the sub-sample of 96% of unique comments. A link exists between two nodes when a commentator makes a comment on a video. We run an Exponential Random Graph Model (ERGM) approach to evaluate which characteristics influence the probability of commenting a video. The creation of a link will be explained in terms of common video features, such as duration, quality, number of likes, number of views, etc. Our data is relevant for the period of 2020-2021 and focuses on the French YouTube environment. From this set of 391 588 videos, we extract the channels which can be monetized according to YouTube regulations (channels with at least 1000 subscribers and more than 4000 hours of viewing time during the last twelve months).In the end, we have a data set of 128 462 videos which consist of 4093 channels. Based on these videos, we have a data set of 1 032 771 unique commentators, with a mean of 2 comments per a commentator, a minimum of 1 comment each, and a maximum of 584 comments.

Keywords: YouTube, social networks, economics, consumer behaviour

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Authors: Marco Ranzato, Maguelone Vignes

Abstract:

The co-design process recently run by the trans-disciplinary urban laboratory Metrolab Brussels for outlining the architecture of a future integrated health centre in Brussels (Belgium) has highlighted that a buffer place open to the local community is the appropriate cornerstone around which organizing a space where diverse professionals and patients are together. In the context of the migrants 'crisis' in Europe, the growing number of vulnerable people in Brussels and the increasing complexity of the health and welfare systems, the NGO Doctors of the World (DoW) has launched a project funded by The European Regional Development Fund, and aiming to create a new community centre combining social and health services in a poor but changing neighborhood of Brussels. Willing not to make a 'ghetto' of this new integrated service, the NGO looks at hosting different publics in order to make the poorest, marginal and most vulnerable people access to a regular kind of service. As a trans-disciplinary urban research group, Metrolab has been involved in the process of co-designing the architecture of the future centre with a set of various health professionals, social workers, and patients’ representatives. Metrolab drawn on the participants’ practice experiences and knowledge of hosting different kinds of publics and professions in a same structure in order to imagine what rooms should fit into the centre, what atmosphere they should convey, how should they be interrelated and organized, and, concurrently, how the building should fit into the urban frame of its neighborhood. The result is that, in order for an integrated health centre framed in the landscape of a disadvantaged neighborhood to function, it has to work as social community centre offering accessibility and conviviality to diverse social groups. This paper outlines the methodology that Metrolab used to design and conduct, in close collaboration with DoW, a series of 3 workshops. Through sketching and paper modeling, the methodology made participants talk about their experience by projecting them into a situation. It included a combination of individual and collective work in order to sharp participants’ eyes on architectural forms, explicit their thoughts and experience through inter-subjectivity and imagine solutions to the challenges they raised. Such a collaborative method encompasses several challenges about patients’ participation and representation, replicability of the conditions of success and the plurality of the research findings communication formats. This paper underlines how this participatory process has contributed to build knowledge on the few-documented topic of the architecture of community health centres. More importantly, the contribution builds on this participatory process to discuss the importance of adapting the architecture of the new integrated health centre to the changing population of Brussels and to the issues of its specific neighborhood.

Keywords: co-design, health, social innovation, urban lab

Procedia PDF Downloads 150