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| 2. |
- Hernaiz, M., et al.
(författare)
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The contact angle of nanofluids as thermophysical property
- 2019
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797. ; 547, s. 393-406
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Tidskriftsartikel (refereegranskat)abstract
- Droplet volume and temperature affect contact angle significantly. Phase change heat transfer processes of nanofluids – suspensions containing nanometre-sized particles – can only be modelled properly by understanding these effects. The approach proposed here considers the limiting contact angle of a droplet asymptotically approaching zero-volume as a thermophysical property to characterise nanofluids positioned on a certain substrate under a certain atmosphere. Graphene oxide, alumina, and gold nanoparticles are suspended in deionised water. Within the framework of a round robin test carried out by nine independent European institutes the contact angle of these suspensions on a stainless steel solid substrate is measured with high accuracy. No dependence of nanofluids contact angle of sessile droplets on the measurement device is found. However, the measurements reveal clear differences of the contact angle of nanofluids compared to the pure base fluid. Physically founded correlations of the contact angle in dependency of droplet temperature and volume are obtained from the data. Extrapolating these functions to zero droplet volume delivers the searched limiting contact angle depending only on the temperature. It is for the first time, that this specific parameter, is understood as a characteristic material property of nanofluid droplets placed on a certain substrate under a certain atmosphere. Together with the surface tension it provides the foundation of proper modelling phase change heat transfer processes of nanofluids.
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| 3. |
- Duffy, J. Emmett, et al.
(författare)
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Toward a Coordinated Global Observing System for Seagrasses and Marine Macroalgae
- 2019
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Ingår i: Frontiers in Marine Science. - : Frontiers Media S.A.. - 2296-7745. ; 6
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Forskningsöversikt (refereegranskat)abstract
- In coastal waters around the world, the dominant primary producers are benthic macrophytes, including seagrasses and macroalgae, that provide habitat structure and food for diverse and abundant biological communities and drive ecosystem processes. Seagrass meadows and macroalgal forests play key roles for coastal societies, contributing to fishery yields, storm protection, biogeochemical cycling and storage, and important cultural values. These socio-economically valuable services are threatened worldwide by human activities, with substantial areas of seagrass and macroalgal forests lost over the last half-century. Tracking the status and trends in marine macrophyte cover and quality is an emerging priority for ocean and coastal management, but doing so has been challenged by limited coordination across the numerous efforts to monitor macrophytes, which vary widely in goals, methodologies, scales, capacity, governance approaches, and data availability. Here, we present a consensus assessment and recommendations on the current state of and opportunities for advancing global marine macrophyte observations, integrating contributions from a community of researchers with broad geographic and disciplinary expertise. With the increasing scale of human impacts, the time is ripe to harmonize marine macrophyte observations by building on existing networks and identifying a core set of common metrics and approaches in sampling design, field measurements, governance, capacity building, and data management. We recommend a tiered observation system, with improvement of remote sensing and remote underwater imaging to expand capacity to capture broad-scale extent at intervals of several years, coordinated with strati fied in situ sampling annually to characterize the key variables of cover and taxonomic or functional group composition, and to provide ground-truth. A robust networked system of macrophyte observations will be facilitated by establishing best practices, including standard protocols, documentation, and sharing of resources at all stages of work flow, and secure archiving of open-access data. Because such a network is necessarily distributed, sustaining it depends on close engagement of local stakeholders and focusing on building and long-term maintenance of local capacity, particularly in the developing world. Realizing these recommendations will producemore effective, efficient, and responsive observing, a more accurate global picture of change in vegetated coastal systems, and stronger international capacity for sustaining observations.
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| 4. |
- Buschmann, M. H., et al.
(författare)
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Correct interpretation of nanofluid convective heat transfer
- 2018
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Ingår i: International Journal of Thermal Sciences. - : Elsevier BV. - 1290-0729. ; 129, s. 504-531
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Forskningsöversikt (refereegranskat)abstract
- Engineers and scientist have a long tradition in trying to improve the thermophysical properties of convective heat carriers such as water and transformer oil. Technological developments of the last decades allow the dispersion of particle of sizes ranging between 10 and 100 nm in these liquids. In a large number of recent studies the resulting nanofluids have been reported to display anomalously high increase of convective heat transfer. The present study compiles experiments from five independent research teams investigating convective heat transfer in nanofluid flow in pipes, pipe with inserted twisted tape, annular counter flow heat exchanger, and coil and plate heat exchangers. The results of all these experiments unequivocally confirm that Newtonian nanofluid flow can be consistently characterized by employing Nusselt number correlations obtained for single-phase heat transfer liquids such as water when the correct thermophysical properties of the nanofluid are utilized. It is also shown that the heat transfer enhancement provided by nanofluids equals the increase in the thermal conductivity of the nanofluid as compared to the base fluid independent of the nanoparticle concentration or material. These results demonstrate that no anomalous phenomena are involved in thermal conduction and forced convection based heat transfer of nanofluids. The experiments are theoretically supported by a fundamental similarity analysis of nanoparticle motion in nanofluid flow.
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| 5. |
- Buschmann, M. H., et al.
(författare)
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On the proper interpretation of nanofluid convective heat transfer
- 2018
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Ingår i: Proceeding: International Heat Transfer Conference 16. - 2377-424X. ; , s. 2855-2862
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Konferensbidrag (refereegranskat)abstract
- Technological developments of the last decades allow the production and the dispersion of particles of sizes ranging between 10 and 100 nm in liquids. In a large number of recent studies the resulting nanofluids have been reported to display anomalously high increase in convective heat transfer. The present study compiles experiments from five independent research teams investigating convective heat transfer in nanofluid flow in pipes (laminar and turbulent), pipe with inserted twisted tape, annular counter flow heat exchanger, and coil and plate heat exchangers. The results of all these experiments unequivocally confirm that Newtonian nanofluid flow can be consistently characterized by employing Nusselt number correlations obtained for single-phase heat transfer liquids such as water when the correct thermophysical properties of the nanofluid are utilized. It is also shown that the heat transfer enhancement provided by nanofluids equals the increase in the thermal conductivity of the nanofluid as compared to the base fluid independent of the nanoparticle concentration or material. These results demonstrate that no anomalous phenomena are involved in thermal conduction and forced convection based heat transfer of water based nanofluids. The experiments are theoretically supported by a fundamental similarity analysis of nanoparticle motion in nanofluid flow.
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| 6. |
- Clayton, Aled, et al.
(författare)
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Summary of the ISEV workshop on extracellular vesicles as disease biomarkers, held in Birmingham, UK, during December 2017
- 2018
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Ingår i: Journal of Extracellular Vesicles. - : Wiley. - 2001-3078. ; 7
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- © 2018 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group on behalf of The International Society for Extracellular Vesicles. This report summarises the presentations and activities of the ISEV Workshop on extracellular vesicle biomarkers held in Birmingham, UK during December 2017. Among the key messages was broad agreement about the importance of biospecimen science. Much greater attention needs to be paid towards the provenance of collected samples. The workshop also highlighted clear gaps in our knowledge about pre-analytical factors that alter extracellular vesicles (EVs). The future utility of certified standards for credentialing of instruments and software, to analyse EV and for tracking the influence of isolation steps on the structure and content of EVs were also discussed. Several example studies were presented, demonstrating the potential utility for EVs in disease diagnosis, prognosis, longitudinal serial testing and stratification of patients. The conclusion of the workshop was that more effort focused on pre-analytical issues and benchmarking of isolation methods is needed to strengthen collaborations and advance more effective biomarkers.
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| 8. |
- Leyton, A., et al.
(författare)
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Identification and efficient extraction method of phlorotannins from the brown seaweed Macrocystis pyrifera using an orthogonal experimental design
- 2016
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Ingår i: Algal Research. - : Elsevier. - 2211-9264. ; 16, s. 201-208
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Tidskriftsartikel (refereegranskat)abstract
- Abstract The brown seaweed contains a type polyphenol compound characteristic of its species, the phlorotannins, which are produced from the polymerization of phloroglucinol units. They have been extensively studied due to their pharmacological and nutraceutical properties, but there is still a need for an optimized extraction protocol. In this study, the brown seaweed Macrocystis pyrifera was employed to determine the best conditions for extraction of phlorotannins. A set of different variables were evaluated such as the use of pre-treatment, type of solvent, drying temperature, particle size, temperature and extraction time as well as the solid/liquid ratio upon extraction. The optimal conditions for the extraction of phlorotannins were: pre-treatment with hexane, extraction with water, drying temperature 40 °C, particle size below 1.4 mm, at 55 °C for 4 h and a solid-to-liquid ratio of 1:15. Under these conditions, the concentration of phlorotannins achieved in the extract was 200.5 ± 5.6 mg gallic acid equivalent (GAE)/100 g dry seaweed (DS) and total antioxidant activity of the extract of 38.4 ± 2.9 mg trolox equivalent (TE)/100 g DS. Further, it was possible to identify two phlorotannins through HPLC-ESI-MS analyses: phloroeckol and a tetrameric phloroglucinol. These phlorotannins have been reported in the literature to have an antidiabetic effect and prevention of Alzheimer's disease for phloroeckol, and free radical scavenging ability and antiallergic effect for tetrameric phloroglucinol. Therefore, the extract of phlorotannins has potential as medicinal foods or therapeutics for human health applications.
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