189 research outputs found

    Participation in co-design: In search of a recipe for improved cookstoves in urban Indian slums

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    This study responds to the need for participatory, context-oriented approaches to address the growing health threat of indoor air pollution faced by marginalised communities of urban India. It explored the application of the co-designing model employed by Project Exhale in two non-notified slums in Bangalore, by analysing processes and tools of multi-stakeholder collaboration, the knowledge that emerged from them, and its translation into the designing of improved cookstoves. Bringing the end-users, designers and researchers onto a common platform led to the generation of contextual, user-knowledge and technical expertise, which were transferred to the development of the prototype. In this process, stoves’ suitability concerns traditionally raised in literature are not seen as barriers to implementation, but issues that can be addressed and negotiated through participatory methods. The involved actors experienced a parting from pre-defined, traditional roles towards more flexible ones, as required by the project at different stages. Tools employed for the knowledge exchanged within this community of practice needed continuous exploration, negotiation and adjusting, as transferring the co-designing model in resource-limited settings demands higher flexibility and a grounding of activities in local experiences

    Operando Laboratory-Based Multi-Edge X-Ray Absorption Near-Edge Spectroscopy of Solid Catalysts

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    Laboratory-based X-ray absorption spectroscopy (XAS) and especially X-ray absorption near-edge structure (XANES) offers new opportunities in catalyst characterization and presents not only an alternative, but also a complementary approach to precious beamtime at synchrotron facilities. We successfully designed a laboratory-based setup for performing operando , quasi-simultaneous XANES analysis at multiple K edges, more specifically, operando XANES of mono-, bi-, and trimetallic CO 2 hydrogenation catalysts containing Ni, Fe, and Cu. Detailed operando XANES studies of the multi-element solid catalysts revealed metal-dependent differences in the reducibility and re-oxidation behavior and their influence on the catalytic performance in CO 2 hydrogenation. The applicability of operando laboratory-based XANES at multiple K edges paves the way for advanced multi-element catalyst characterization complementing detailed studies at synchrotron facilities.Peer reviewe

    Structure Sensitivity and Evolution of Nickel-Bearing Nitrogen-Doped Carbons in the Electrochemical Reduction of CO2

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    The emergence of nickel single atoms on nitrogen-doped carbons as high-performance catalysts amenable to rationalization due to their well-defined structure could lead to applicable technologies for the electrocatalytic CO2 reduction reaction (eCO2RR). However, real materials are unlikely to display a uniform site structure, which limits the scope of current efforts focused on idealized models for future implementation. Here, we prepare distinct nickel entities (single atoms or nanoparticles) on nitrogen-doped carbons and evaluate them in eCO2RR. Single atoms demonstrate a characteristic high selectivity to CO. However, this is not altered by the presence of metal nanoparticles formed upon reducing the nitrogen content of the carrier. In contrast, nanoparticles incorporated via a colloidal route promote the parasitic hydrogen evolution reaction. In these systems, the CO selectivity evolves upon repeated exposure to potential, reaching values comparable to single atoms. By introducing CO stripping voltammetry as a characterization tool for this class of materials, we identify a decreased metallic surface, suggesting that the nanoparticle surface is altered by CO. The findings highlight the critical role of dynamic effects in catalyst design for eCO2RR

    Pd-LaFeO3 catalysts in aqueous ethanol: Pd reduction, leaching, and structural transformations in the presence of a base

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    The reactive behavior of three catalysts based on Pd-loaded LaFeO3 was investigated in terms of the reducibility of Pd and its propensity to leaching into the liquid phase in flowing solutions prototypical of C–C coupling catalysis in a continuous flow reactor cell. In situ quick extended X-ray absorption fine structure spectroscopy showed that Pd remains stable and nonreducible in the flowing ethanol/water solvent mixture under heating to 353 K. However, ex situ transmission electron microscopy, high-energy X-ray diffraction, and fluorescence yield Fe K-edge X-ray absorption near-edge structure show that the addition of a significant amount of base (K2CO3, 0.1 M) results in the structural degradation of the perovskite support as well as the mobilization of Pd along the sample bed that is dependent on the structure and crystallite size of the perovskite. The results are discussed in terms of the use of perovskite-type oxides in various areas of research where they are placed in contact with liquid phases of variable temperature and elevated pH

    Platinum–Vanadium Oxide Nanotube Hybrids

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    The present contribution reports on the features of platinum-based systems supported on vanadium oxide nanotubes. The synthesis of nanotubes was carried out using a commercial vanadium pentoxide via hydrothermal route. The nanostructured hybrid materials were prepared by wet impregnation using two different platinum precursors. The formation of platinum nanoparticles was evaluated by applying distinct reduction procedures. All nanostructured samples were essentially analysed by X-ray diffraction and transmission electron microscopy. After reduction, transmission electron microscopy also made it possible to estimate particle size distribution and mean diameter calculations. It could be seen that all reduction procedures did not affect the nanostructure of the supports and that the formation of metallic nanoparticles is quite efficient with an indistinct distribution along the nanotubes. Nevertheless, the reduction procedure determined the diameter, dispersion and shape of the metallic particles. It could be concluded that the use of H2PtCl6 is more suitable and that the use of hydrogen as reducing agent leads to a nanomaterial with unagglomerated round-shaped metallic particles with mean size of 6–7 nm

    Operando Laboratory-based Multi-edge X-ray Absorption Near-Edge Spectroscopy of Solid Catalysts

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    Laboratory-based X-ray absorption spectroscopy (XAS) and especially X-ray absorption near-edge structure (XANES) offers new opportunities in catalyst characterization and presents not only an alternative, but also a complementary approach to precious beamtime at synchrotron facilities. We successfully designed a laboratory-based setup for performing operando , quasi-simultaneous XANES analysis at multiple K edges, more specifically, operando XANES of mono-, bi-, and trimetallic CO 2 hydrogenation catalysts containing Ni, Fe, and Cu. Detailed operando XANES studies of the multi-element solid catalysts revealed metal-dependent differences in the reducibility and re-oxidation behavior and their influence on the catalytic performance in CO 2 hydrogenation. The applicability of operando laboratory-based XANES at multiple K edges paves the way for advanced multi-element catalyst characterization complementing detailed studies at synchrotron facilities

    Dark clouds in co-creation, and their silver linings practical challenges we faced in a participatory project in a resource-constrained community in India, and how we overcame (some of) them

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    BACKGROUND: While any type of field-based research is challenging, building action-oriented, participatory research in resource-constrained settings can be even more so. OBJECTIVE: In this article, we aim to examine and provide insights into some of the practical challenges that were faced during the course of a participatory project based in two non-notified slums in Bangalore, India, aiming to build solutions to indoor air pollution from cooking on traditional cook stoves. METHODS: The article draws upon experiences of the authors as field researchers engaged in a community-based project that adopted an exploratory, iterative design to its planning and implementation, which involved community visits, semi-structured interviews, prioritization workshops, community forums, photo voice activities, chulha-building sessions and cooking trials. RESULTS: The main obstacles to field work were linked to fostering open, continued dialogue with the community, aimed at bridging the gap between the 'scientific' and the 'local' worlds. Language and cultural barriers led to a reliance on interpreters, which affected both the quality of the interaction as well as the relationship between the researchers and the community that was built out of that interaction. The transience in housing and location of members of the community also led to difficulties in following up on incomplete information. Furthermore, facilitating meaningful participation from the people within the context of restricted resources, differing priorities, and socio-cultural diversity was particularly challenging. These were further compounded by the constraints of time and finances brought on by the embeddedness of the project within institutional frameworks and conventional research requirements of a fixed, pre-planned and externally determined focus, timeline, activities and benchmarks for the project. CONCLUSIONS: This article calls for revisiting of scientific conventions and funding prerequisites, in order to create spaces that support flexible, emergent and adaptive field-based research projects which can respond effectively to the needs and priorities of the community

    Healthcare workers’ beliefs, motivations and behaviours affecting adequate provision of sexual and reproductive healthcare services to adolescents in Cape Town, South Africa: a qualitative study

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    BACKGROUND: Adolescents’ sexual and reproductive healthcare (SRH) needs have been prioritized globally, and they have the rights to access and utilize SRH services for their needs. However, adolescents under-utilize SRH services, especially in sub-Saharan Africa. Many factors play a role in the under-utilization of SRH services by adolescents, such as the attitude and behaviour of healthcare workers. The aim of this study therefore, was to explore and gain an in-depth understanding of healthcare workers’ beliefs, motivations and behaviours affecting adequate provision of these services to adolescents in South Africa. METHODS: Twenty-four healthcare workers in public SRH services in Cape Town, South Africa participated in this qualitative study through focus group discussions. To fulfill the aims of this study, nine focus group discussions were conducted among the SRH nurses. RESULTS: SRH nurses indicated that they are experiencing challenges with the concept and practice of termination of pregnancy. They explained that this practice contradicted their opposing beliefs and values. Some nurses felt that they had insufficient SRH skills, which hinder their provision of adequate SRH services to adolescents, while others described constraints within the health system such as not enough time to provide the necessary care. They also explained having limited access to schools where they can provide SRH education and pregnancy prevention services in the surrounding area. CONCLUSIONS: Nurses are faced with numerous challenges when providing SRH services to adolescents. Providing the nurses with training programmes that emphasize value clarification may help them to separate their personal beliefs and norms from the workplace practice. This may help them to focus on the needs of the adolescent in a way that is beneficial to them. At the health systems level, issues such as clinic operating hours need to be structured such that the time pressure and constraints upon the nurse is relieved

    Rab27a and Rab27b control different steps of the exosome secretion pathway

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    Exosomes are secreted membrane vesicles that share structural and biochemical characteristics with intraluminal vesicles of multivesicular endosomes (MVEs). Exosomes could be involved in intercellular communication and in the pathogenesis of infectious and degenerative diseases. The molecular mechanisms of exosome biogenesis and secretion are, however, poorly understood. Using an RNA interference (RNAi) screen, we identified five Rab GTPases that promote exosome secretion in HeLa cells. Among these, Rab27a and Rab27b were found to function in MVE docking at the plasma membrane. The size of MVEs was strongly increased by Rab27a silencing, whereas MVEs were redistributed towards the perinuclear region upon Rab27b silencing. Thus, the two Rab27 isoforms have different roles in the exosomal pathway. In addition, silencing two known Rab27 effectors, Slp4 (also known as SYTL4, synaptotagmin-like 4) and Slac2b (also known as EXPH5, exophilin 5), inhibited exosome secretion and phenocopied silencing of Rab27a and Rab27b, respectively. Our results therefore strengthen the link between MVEs and exosomes, and introduce ways of manipulating exosome secretion in vivo
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