28 research outputs found
Mild sonochemical exfoliation of bromine-intercalated graphite: a new route towards graphene
A method to produce suspensions of graphene sheets by combining
solution-based bromine intercalation and mild sonochemical exfoliation is
presented. Ultrasonic treatment of graphite in water leads to the formation of
suspensions of graphite flakes. The delamination is dramatically improved by
intercalation of bromine into the graphite before sonication. The bromine
intercalation was verified by Raman spectroscopy as well as by x-ray
photoelectron spectroscopy (XPS), and density functional theory (DFT)
calculations show an almost ten times lower interlayer binding energy after
introducing Br2 into the graphite. Analysis of the suspended material by
transmission and scanning electron microscopy (TEM and SEM) revealed a
significant content of few-layer graphene with sizes up to 30 m,
corresponding to the grain size of the starting material.Comment: 10 pages 4 figure
Challenges for Sustained Observing and Forecasting Systems in the Mediterranean Sea
The Mediterranean community represented in this paper is the result of more than 30 years of EU and nationally funded coordination, which has led to key contributions in science concepts and operational initiatives. Together with the establishment of operational services, the community has coordinated with universities, research centers, research infrastructures and private companies to implement advanced multi-platform and integrated observing and forecasting systems that facilitate the advancement of operational services, scientific achievements and mission-oriented innovation. Thus, the community can respond to societal challenges and stakeholders needs, developing a variety of fit-for-purpose services such as the Copernicus Marine Service. The combination of state-of-the-art observations and forecasting provides new opportunities for downstream services in response to the needs of the heavily populated Mediterranean coastal areas and to climate change. The challenge over the next decade is to sustain ocean observations within the research community, to monitor the variability at small scales, e.g., the mesoscale/submesoscale, to resolve the sub-basin/seasonal and inter-annual variability in the circulation, and thus establish the decadal variability, understand and correct the model-associated biases and to enhance model-data integration and ensemble forecasting for uncertainty estimation. Better knowledge and understanding of the level of Mediterranean variability will enable a subsequent evaluation of the impacts and mitigation of the effect of human activities and climate change on the biodiversity and the ecosystem, which will support environmental assessments and decisions. Further challenges include extending the science-based added-value products into societal relevant downstream services and engaging with communities to build initiatives that will contribute to the 2030 Agenda and more specifically to SDG14 and the UN's Decade of Ocean Science for sustainable development, by this contributing to bridge the science-policy gap. The Mediterranean observing and forecasting capacity was built on the basis of community best practices in monitoring and modeling, and can serve as a basis for the development of an integrated global ocean observing system
Challenges for Sustained Observing and Forecasting Systems in the Mediterranean Sea
The Mediterranean community represented in this paper is the result of more than 30 years of EU and nationally funded coordination, which has led to key contributions in science concepts and operational initiatives. Together with the establishment of operational services, the community has coordinated with universities, research centers, research infrastructures and private companies to implement advanced multi-platform and integrated observing and forecasting systems that facilitate the advancement of operational services, scientific achievements and mission-oriented innovation. Thus, the community can respond to societal challenges and stakeholders needs, developing a variety of fit-for-purpose services such as the Copernicus Marine Service. The combination of state-of-the-art observations and forecasting provides new opportunities for downstream services in response to the needs of the heavily populated Mediterranean coastal areas and to climate change. The challenge over the next decade is to sustain ocean observations within the research community, to monitor the variability at small scales, e.g., the mesoscale/submesoscale, to resolve the sub-basin/seasonal and inter-annual variability in the circulation, and thus establish the decadal variability, understand and correct the model-associated biases and to enhance model-data integration and ensemble forecasting for uncertainty estimation. Better knowledge and understanding of the level of Mediterranean variability will enable a subsequent evaluation of the impacts and mitigation of the effect of human activities and climate change on the biodiversity and the ecosystem, which will support environmental assessments and decisions. Further challenges include extending the science-based added-value products into societal relevant downstream services and engaging with communities to build initiatives that will contribute to the 2030 Agenda and more specifically to SDG14 and the UN's Decade of Ocean Science for sustainable development, by this contributing to bridge the science-policy gap. The Mediterranean observing and forecasting capacity was built on the basis of community best practices in monitoring and modeling, and can serve as a basis for the development of an integrated global ocean observing system
Conservação e restauro de uma urna em vidro do século I d.C., encontrada em Mértola (Portugal)
International audienceThe evolution of capillary forces during evap-oration and the corresponding changes in the geometrical characteristics of liquid (water) bridges between two glass spheres with constant separation are examined experimen-tally. For comparison, the liquid bridges were also tested for mechanical extension (at constant volume). The obtained results reveal substantial differences between the evolution of capillary force due to evaporation and the evolution due to extension of the liquid bridges. During both evaporation and extension, the change of interparticle capillary forces consists in a force decrease to zero either gradually or via rupture of the bridge. At small separations between the grains (short & wide bridges) during evaporation and at large volumes during extension, there is a slight initial increase of force. During evaporation, the capillary force decreases slowly at the begin-ning of the process and quickly at the end of the process; during extension, the capillary force decreases quickly at the beginning and slowly at the end of the process. Rup-ture during evaporation of the bridges occurs most abruptly for bridges with wider separations (tall and thin), sometimes occurring after only 25 % of the water volume was evapo-rated. The evolution (pinning/depinning) of two geometri-cal characteristics of the bridge, the diameter of the three-phase contact line and the "apparent" contact angle at the solid/liquid/gas interface, seem to control the capillary force evolution. The findings are of relevance to the mechanics of unsaturated granular media in the final phase of drying
Optimisation of Perioperative Cardiovascular Management to Improve Surgical Outcome II (OPTIMISE II) trial: study protocol for a multicentre international trial of cardiac output-guided fluid therapy with low-dose inotrope infusion compared with usual care in patients undergoing major elective gastrointestinal surgery.
INTRODUCTION: Postoperative morbidity and mortality in older patients with comorbidities undergoing gastrointestinal surgery are a major burden on healthcare systems. Infections after surgery are common in such patients, prolonging hospitalisation and reducing postoperative short-term and long-term survival. Optimal management of perioperative intravenous fluids and inotropic drugs may reduce infection rates and improve outcomes from surgery. Previous small trials of cardiac-output-guided haemodynamic therapy algorithms suggested a modest reduction in postoperative morbidity. A large definitive trial is needed to confirm or refute this and inform widespread clinical practice. METHODS: The Optimisation of Perioperative Cardiovascular Management to Improve Surgical Outcome II (OPTIMISE II) trial is a multicentre, international, parallel group, open, randomised controlled trial. 2502 high-risk patients undergoing major elective gastrointestinal surgery will be randomly allocated in a 1:1 ratio using minimisation to minimally invasive cardiac output monitoring to guide protocolised administration of intravenous fluid combined with low-dose inotrope infusion, or usual care. The trial intervention will be carried out during and for 4 hours after surgery. The primary outcome is postoperative infection of Clavien-Dindo grade II or higher within 30 days of randomisation. Participants and those delivering the intervention will not be blinded to treatment allocation; however, outcome assessors will be blinded when feasible. Participant recruitment started in January 2017 and is scheduled to last 3 years, within 50 hospitals worldwide. ETHICS/DISSEMINATION: The OPTIMISE II trial has been approved by the UK National Research Ethics Service and has been approved by responsible ethics committees in all participating countries. The findings will be disseminated through publication in a widely accessible peer-reviewed scientific journal. TRIAL REGISTRATION NUMBER: ISRCTN39653756.The OPTIMISE II trial is supported by Edwards Lifesciences (Irvine, CA) and the UK National Institute for Health Research through RMP’s NIHR Professorship
Heat transfer performance of a lubricant-infused thermosyphon at various filling ratios
The effect of the filling ratio (25% ≤ FR ≤ 98%) on the heat transfer performance of a novel two-phase closed thermosyphon (TPCT) combined with a superhydrophilic (SHi) evaporator and slippery lubricant-infused porous surface (SLIPS) condenser (TPCT-SHiSL) is systematically investigated in the present study. On the evaporator side, experimental results show that a different evaporation mechanism takes place dependent on the filling ratio, which has a strong impact on the overall heat transfer performance. Film evaporation plays a dominant role at the filling ratio of 25% and at the filling ratios of 40% and 70% at low heat flux. Nonetheless, film evaporation is gradually reduced and pool boiling becomes important at the filling ratios of 40% and 70% for moderate and high heat fluxes. Finally, pool boiling plays a dominant role for the TPCT-SHiSL at the filling ratio of 98%. In the case of the condenser, the condensation heat transfer of the SLIPS is reduced with increasing filling ratio. Balancing between the thermal resistance and heat transfer capacity, the TPCT-SHiSL at the filling ratio of 40% shows the best heat transfer performance
Rhodium-sulfonated diphosphine catalysts in aqueous hydroformylation of vinyl arenes: high-pressure NMR and IR studies
Hydroformylation of vinyl arenes (p-metboxystyrene and p-fluorostyrene) was performed in aqueous solutions using as catalyst precursor [Rh(mu-OMe)(cod)](2) (cod = 1,5-cyclooctadiene) associated with the sulfonated 1,3-diarylphosphines (tetra-sulfonated 1,3-bis(diphenylphosphino)propane (dpppts)) and the chiral (S,S)-bdppts (2,4-bis(diphenylphosphino)pentane). The influence of pH on the reaction rate was studied. After 24 h conversion was practically total with the achiral system in basic medium for the substituted styrene substrates. Selectivities in aldehydes were >85%. At neutral pH, the asymmetric hydroforrnylation of p-substituted styrenes using the rhodium-bdppts systems provides low conversion but the enantioselectivities were as high as 66%, the highest reported so far for this kind of substrates in aqueous systems. Comparison experiments using rhodium precursors with the non-sulfonated bdpp in organic solvents indicated that the enantioselectivity was higher in aqueous solutions for the p-methoxystyrene derivative and slightly lower for p-fluorostyrene. However, in both the cases the conversions in aqueous systems were low. High-pressure NMR and IR experiments in water/methanol indicate that [RhH(CO)(2)(sulfonated diphosphine)] species form under catalytic conditions in basic medium. At neutral pH, the main species observed in the case of the bdppts ligand is [Rh(bdppts)(2)](+) which may account for the low conversion in this medium. (C) 2002 Elsevier Science B.V. All rights reserved