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- Mattos, Caio R. C., et al.
(författare)
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Rainfall and topographic position determine tree embolism resistance in AmazÃŽnia and Cerrado sites
- 2023
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Ingår i: Environmental Research Letters. - : Institute of Physics Publishing (IOPP). - 1748-9326. ; 18:11
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Tidskriftsartikel (refereegranskat)abstract
- Droughts are predicted to increase in both frequency and intensity by the end of the 21st century, but ecosystem response is not expected to be uniform across landscapes. Here we assess the importance of the hill-to-valley hydrologic gradient in shaping vegetation embolism resistance under different rainfall regimes using hydraulic functional traits. We demonstrate that rainfall and hydrology modulate together the embolism resistance of tree species in different sites and topographic positions. Although buffered by stable access to groundwater, valley plants are intrinsically more vulnerable to drought-induced embolism than those on hills. In all study sites, the variability in resistance to embolism is higher on hills than on valleys, suggesting that the diversity of strategies to cope with drought is more important for tree communities on hills. When comparing our results with previously published data across the tropics, we show greater variability at the local scale than previously reported. Our results reinforce the urgent need to extend sampling efforts across rainfall regimes and topographic positions to improve the characterization of ecosystem resistance to drought at finer spatial scales.
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- Duezguen, Ali, et al.
(författare)
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Nanostructured materials in potentiometry
- 2011
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Ingår i: Analytical and Bioanalytical Chemistry. - : Springer Science and Business Media LLC. - 1618-2642 .- 1618-2650. ; 399:1, s. 171-181
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Tidskriftsartikel (refereegranskat)
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- Guinovart, Tomas, et al.
(författare)
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A reference electrode based on polyvinyl butyral (PVB) polymer for decentralized chemical measurements
- 2014
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Ingår i: Analytica Chimica Acta. - : Elsevier. - 0003-2670 .- 1873-4324. ; 821, s. 72-80
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Tidskriftsartikel (refereegranskat)abstract
- A new solid-state reference electrode using a polymeric membrane of polyvinyl butyral (PVB), Ag/AgCl and NaCl to be used in decentralized chemical measurements is presented. The electrode is made by drop-casting the membrane cocktail onto a glassy carbon (GC) substrate. A stable potential (less than 1 mV dec−1) over a wide range of concentrations for the several chemical species tested is obtained. No significant influence to changes in redox potential, light and pH are observed. The response of this novel electrode shows good correlation when compared with a conventional double-junction reference electrode. Also good long-term stability (90 ± 33 μV/h) and a lifetime of approximately 4 months are obtained. Aspects related to the working mechanisms are discussed. Atomic Force Microscopy (AFM) studies reveal the presence of nanopores and channels on the surface, and electrochemical impedance spectroscopy (EIS) of optimized electrodes show low bulk resistances, usually in the kΩ range, suggesting that a nanoporous polymeric structure is formed in the interface with the solution. Future applications of this electrode as a disposable device for decentralized measurements are discussed. Examples of the utilization on wearable substrates (tattoos, fabrics, etc) are provided.
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- Guinovart, Tomas, et al.
(författare)
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Potentiometric sensors using cotton yarns, carbon nanotubes and polymeric membranes
- 2013
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Ingår i: The Analyst. - : Royal Society of Chemistry. - 0003-2654 .- 1364-5528. ; 138:18, s. 5208-5215
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Tidskriftsartikel (refereegranskat)abstract
- A simple and generalized approach to build electrochemical sensors for wearable devices is presented. Commercial cotton yarns are first turned into electrical conductors through a simple dyeing process using a carbon nanotube ink. These conductive yarns are then partially coated with a suitable polymeric membrane to build ion-selective electrodes. Potentiometric measurements using these yarn-potentiometric sensors are demonstrated. Examples of yarns that can sense pH, K+ and NH4+ are presented. In all cases, these sensing yarns show limits of detection and linear ranges that are similar to those obtained with lab-made solid-state ion-selective electrodes. Through the immobilization of these sensors in a band-aid, it is shown that this approach could be easily implemented in a wearable device. Factors affecting the performance of the sensors and future potential applications are discussed.
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- Kerric, Gaelle, et al.
(författare)
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Nanostructured assemblies for ion-sensors : functionalization of multi-wall carbon nanotubes with benzo-18-crown-6 for Pb2+ determination
- 2012
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Ingår i: Journal of Materials Chemistry. - : Royal Society of Chemistry. - 0959-9428 .- 1364-5501. ; 22:32, s. 16611-16617
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis and full characterization of new hybrid materials, i.e. benzo-18-crown-6 covalently linked to multi-wall carbon nanotubes – incorporating first and second generation dendrimer approaches – are reported here. Furthermore, the benefit of using these new nanostructured assemblies is demonstrated for solid-contact ion-selective sensor configuration. Both selective recognition and ion-to-electron transduction events take place at the same hybrid nanostructured material. Functionalization of multi-wall carbon nanotubes (MWCNTs) plays a key role in the development of such devices not only allowing an improvement of the analytical parameters such as selectivity and stability but also providing simplicity in the manufacturing stages.
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