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- Antoniazzi, Igor, et al.
(författare)
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Oxygen intercalated graphene on SiC(0001) : Multiphase SiOx layer formation and its influence on graphene electronic properties
- 2020
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Ingår i: Carbon. - : Elsevier BV. - 0008-6223. ; 167, s. 746-759
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Tidskriftsartikel (refereegranskat)abstract
- Low-dimensionality materials are highly susceptible to interfaces. Indeed, intercalation of different chemical species in between epitaxial graphene and silicon carbide (SiC), for instance, may decouple the graphene with respect to the substrate due to the conversion of the buffer layer into a graphene layer. O-intercalation is known to release the strain of such 2D material and to lead to the formation of high structural quality AB-stacked bilayer graphene. Nonetheless, this interface transformation concomitantly degrades graphene electronic transport properties. In this work we employed different techniques in order to better understand the structure of the graphene/SiC interface generated by O-intercalation and to elucidate the origin of the poor electronic properties of graphene. Experimental results revealed the formation of a SiO2 rich layer with a defective transition layer in between it and the SiC, which is characterized by the existence of silicon oxycarbide structures. Scanning tunneling spectroscopy measurements revealed an extensive presence of electronic states just around the Fermi level all over the sample surface, which may suppress the charge carriers mobility around this region. According to theoretical calculations, such states are mainly due to the formation of silicon oxicarbides within the interfacial layer.
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| 2. |
- Sparovek, Gerd, 1962, et al.
(författare)
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Sustainable bioproducts in Brazil: disputes and agreements on a common ground agenda for agriculture and nature protection
- 2016
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Ingår i: Biofuels, Bioproducts and Biorefining. - : Wiley. - 1932-1031 .- 1932-104X. ; 10:3, s. 204-221
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Tidskriftsartikel (refereegranskat)abstract
- A key question for food, biofuels, and bioproducts production is how agriculture affects the environment, and social and economic development. In Brazil, a large agricultural producer and among the biologically wealthiest of nations, this question is challenging and opinions often clash. The Brazilian parliament and several stakeholders have recently debated the revision of the Forest Act, the most important legal framework for conservation of natural vegetation on Brazilian private agricultural lands. Past decades have shown improvements in the agricultural sector with respect to productivity and efficiency, along with great reductions in deforestation and growth of environmentally certified production. However, the opposing sides in the debate have ignored this progress and instead continue to entrench their respective combative positions. A structured exchange involving nine experts associated with major producer interests (livestock, crops, planted forest, and charcoal) and environmental NGOs was moderated based on a framework that sorted viewpoints into four categories: (i) common ground - compatible interests considered to be high priority for Brazilian sustainable agricultural development; (ii) serving exclusive nature conservation interest; (iii) serving exclusive agricultural production interest; and (iv) mainly serving the purpose of sustaining dispute. We conclude that the majority of actions and expected future trends reflect achievements and ambitions to balance production and conservation, but much public opinion - and in turn decisions in the parliament and government for agriculture and conservation - is shaped by a perceived conflict between these objectives and a debate that has become, at least to some extent, an end in itself.
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| 7. |
- Romero, Gustavo Q., et al.
(författare)
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Climate variability and aridity modulate the role of leaf shelters for arthropods : A global experiment
- 2022
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 28:11, s. 3694-3710
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Tidskriftsartikel (refereegranskat)abstract
- Current climate change is disrupting biotic interactions and eroding biodiversity worldwide. However, species sensitive to aridity, high temperatures, and climate variability might find shelter in microclimatic refuges, such as leaf rolls built by arthropods. To explore how the importance of leaf shelters for terrestrial arthropods changes with latitude, elevation, and climate, we conducted a distributed experiment comparing arthropods in leaf rolls versus control leaves across 52 sites along an 11,790 km latitudinal gradient. We then probed the impact of short- versus long-term climatic impacts on roll use, by comparing the relative impact of conditions during the experiment versus average, baseline conditions at the site. Leaf shelters supported larger organisms and higher arthropod biomass and species diversity than non-rolled control leaves. However, the magnitude of the leaf rolls' effect differed between long- and short-term climate conditions, metrics (species richness, biomass, and body size), and trophic groups (predators vs. herbivores). The effect of leaf rolls on predator richness was influenced only by baseline climate, increasing in magnitude in regions experiencing increased long-term aridity, regardless of latitude, elevation, and weather during the experiment. This suggests that shelter use by predators may be innate, and thus, driven by natural selection. In contrast, the effect of leaf rolls on predator biomass and predator body size decreased with increasing temperature, and increased with increasing precipitation, respectively, during the experiment. The magnitude of shelter usage by herbivores increased with the abundance of predators and decreased with increasing temperature during the experiment. Taken together, these results highlight that leaf roll use may have both proximal and ultimate causes. Projected increases in climate variability and aridity are, therefore, likely to increase the importance of biotic refugia in mitigating the effects of climate change on species persistence.
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