We discuss a method of analysis of symmetric electromagnetic components with magnetic media based on magnetic group theory. In this description, some of the irreducible corepresentations assume ...complex values exp(iθ) with the real parameter θ. A possible physical interpretation of this parameter is given. We demonstrate the application of the symmetry-adapted linear combination method combined with the corepresentation theory to the problem of current modes in an array of magnetized graphene elements where Faraday and Kerr effects can exist. The elements are described by the magnetic symmetry C4 or C4v(C4). The scattering matrix of the array and its eigensolutions are defined and analyzed and some numerical simulations are presented as well. An example of a waveguide described by symmetry C4v(C2v) with a specific type of degeneracy is also discussed.
Tropical forests store large amounts of carbon and high biodiversity, but are being degraded at alarming rates. The emerging global Forest and Landscape Restoration (FLR) agenda seeks to limit global ...climate change by removing carbon dioxide from the atmosphere through the growth of trees. In doing so, it may also protect biodiversity as a free cobenefit, which is vital given the massive shortfall in funding for biodiversity conservation. We investigated whether natural forest regeneration on abandoned pastureland offers such cobenefits, focusing for the first time on the recovery of taxonomic diversity (TD), phylogenetic diversity (PD) and functional diversity (FD) of trees, including the recovery of threatened and endemic species richness, within isolated secondary forest (SF) fragments. We focused on the globally threatened Brazilian Atlantic Forest, where commitments have been made to restore 1 million hectares under FLR. Three decades after land abandonment, regenerating forests had recovered ~20% (72 Mg/ha) of the above‐ground carbon stocks of a primary forest (PF), with cattle pasture containing just 3% of stocks relative to PFs. Over this period, SF recovered ~76% of TD, 84% of PD and 96% of FD found within PFs. In addition, SFs had on average recovered 65% of threatened and ~30% of endemic species richness of primary Atlantic forest. Finally, we find positive relationships between carbon stock and tree diversity recovery. Our results emphasize that SF fragments offer cobenefits under FLR and other carbon‐based payments for ecosystem service schemes (e.g. carbon enhancements under REDD+). They also indicate that even isolated patches of SF could help to mitigate climate change and the biodiversity extinction crisis by recovering species of high conservation concern and improving landscape connectivity.
We investigated whether natural forest regeneration on abandoned pastureland offers such cobenefits, focusing for the first time on the recovery of taxonomic, phylogenetic diversity and functional diversity of trees, including the recovery of threatened and endemic species, within isolated secondary forest (SF) fragments. Our results emphasize that SF fragments offer cobenefits under FLR and other carbon‐based payments for ecosystem service schemes (e.g. carbon enhancements under REDD+). They also indicate that even isolated patches of SF could help to mitigate climate change and the biodiversity extinction crisis by recovering species of high conservation concern and improving landscape connectivity improving landscape connectivity.
Under the UN-Decade of Ecosystem Restoration and Bonn Challenge, second-growth forest is promoted as a global solution to climate change, degradation and associated losses of biodiversity and ...ecosystem services. Second growth is often invaded by alien tree species and understanding how this impacts carbon stock and biodiversity recovery is key for restoration planning. We assessed carbon stock and tree diversity recovery in second growth invaded by two
species and non-invaded second growth, with associated edge effects, in the Brazilian Atlantic Forest. Carbon stock recovery in non-invaded forests was threefold lower than in invaded forests. Increasingly isolated, fragmented and deforested areas had low carbon stocks when non-invaded, whereas the opposite was true when invaded. Non-invaded forests recovered threefold to sixfold higher taxonomic, phylogenetic and functional diversity than invaded forest. Higher species turnover and lower nestedness in non-invaded than invaded forests underpinned higher abundance of threatened and endemic species in non-invaded forest. Non-invaded forests presented positive relationships between carbon and biodiversity, whereas in the invaded forests we did not detect any relationship, indicating that more carbon does not equal more biodiversity in landscapes with high vulnerability to invasive acacias. To deliver on combined climate change and biodiversity goals, restoration planning and management must consider biological invasion risk. This article is part of the theme issue 'Understanding forest landscape restoration: reinforcing scientific foundations for the UN Decade on Ecosystem Restoration'.
The vast extent of the Amazon Basin has historically restricted the study of its tree communities to the local and regional scales. Here, we provide empirical data on the commonness, rarity, and ...richness of lowland tree species across the entire Amazon Basin and Guiana Shield (Amazonia), collected in 1170 tree plots in all major forest types. Extrapolations suggest that Amazonia harbors roughly 16,000 tree species, of which just 227 (1.4%) account for half of all trees. Most of these are habitat specialists and only dominant in one or two regions of the basin. We discuss some implications of the finding that a small group of species--less diverse than the North American tree flora--accounts for half of the world's most diverse tree community.
Ionic liquids are a class of fluids that requires the attentions of experimentalist and theoreticians. In a new project on synthesis and characterization of new and not-so-new ionic liquids, the ...study of several thermophysical properties of these liquids was started, namely binary diffusion, electrical conductivity, heat capacity, surface tension, viscosity and thermal conductivity. Among others we will study 1-
n-butyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide, (C
4mimNTf
2), 1-
n-butyl-3-methyl-imidazolium dicyanamide, (C
4mimdca), 1-ethyl-3-methyl-imidazolium ethylsulfate, (C
2mimEtOSO
3) and methyltrialkylammonium dicyanamide Aliquat
®336-deriveddca, and in the case of diffusion, their mixtures with water.
It is the purpose of this paper to report data on the density, using vibrating tube densimetry, infinite dilution diffusion coefficients, using the Taylor dispersion method, heat capacity, using DSC equipment and surface tension, using the Wilhelmy plate method. Density measurements were performed at atmospheric pressure between 293 and 363
K and several isotherms, depending on the stability of the compound, up to 60
MPa, with an uncertainty of 0.4%. Measurements were performed at 298.03
K for the infinite dilution measurements, with an uncertainty of 1.3–3.5%, for temperatures between 300 and 370
K for heat capacity, with an uncertainty better than 1.5%, and between 292 and 395
K for surface tension, with an uncertainty of 1.5–1.8%.
A brief analysis of the potential of the fluids studied as engineering heat transfer fluids, namely its heat storage capacity was also performed.
Due to their diverse applications, gold nanoparticles (AuNPs) are expected to increase of in the environment, although few studies are available on their mode of action in aquatic organisms. The ...genotoxicity of AuNPs, alone or combined with the human pharmaceutical gemfibrozil (GEM), an environmental contaminant frequently detected in aquatic systems, including in marine ecosystems, was examined using gilthead seabream erythrocytes as a model system. Fish were exposed for 96 h to 4, 80 and 1600 μg L−1 of 40 nm AuNPs with two coatings – citrate or polyvinylpyrrolidone; GEM (150 μg L−1); and a combination of AuNPs and GEM (80 μg L−1 AuNPs + 150 μg L−1 GEM). AuNPs induced DNA damage and increased nuclear abnormalities levels, with coating showing an important role in the toxicity of AuNPs to fish. The combined exposures of AuNPs and GEM produced an antagonistic response, with observed toxic effects in the mixtures being lower than the predicted. The results raise concern about the safety of AuNPs and demonstrate interactions between them and other contaminants.
•Gold nanoparticles (AuNPs) induced DNA damage in Sparus aurata at 4 μg.L−1.•Erythrocytic nuclear abnormalities (ENAs) increased after exposure to 4 μg.L−1 AuNPs.•The induction of ENAs decreased with citrate coated AuNPs concentration increase.•AuNPs combined exposures with gemfibrozil (GEM) induced DNA damage and ENAs.•AuNPs and GEM combined exposures produced an antagonistic response.
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•Gemfibrozil affected Sparus aurata even at an environmentally relevant concentration.•Gemfibrozil decreased the capability of Sparus aurata to swim against a water flow.•Gemfibrozil ...induced hepatic oxidative damage in gilthead seabream.
Lipid regulators are among the most prescribed human pharmaceuticals worldwide. Gemfibrozil, which belongs to this class of pharmaceuticals, is one of the most frequently encountered in the aquatic environment. However, there is limited information concerning the mechanisms involved in gemfibrozil effects to aquatic organisms, particularly to marine organisms. Based on this knowledge gap, the current study aimed to assess biochemical and behavioral effects following a sublethal exposure to gemfibrozil (1.5, 15, 150, 1500 and 15,000 μg L−1) in the estuarine/marine fish Sparus aurata. After the exposure to 1.5 μg L−1 of gemfibrozil, fish had reduced ability to swim against a water flow and increased lipid peroxidation in the liver. At concentrations between 15–15,000 μg L−1, the activities of some enzymes involved in antioxidant defense were induced, appearing to be sufficient to prevent oxidative damage. Depending on the organ, different responses to gemfibrozil were displayed, with enzymes like catalase being more stimulated in gills, whereas glutathione peroxidase was more activated in liver. Although there were no obvious concentration-response relationships, the integrated biomarker response version 2 (IBRv2) analysis revealed that the highest concentrations of gemfibrozil (between 150–15,000 μg L−1) caused more alterations. All the tested concentrations of gemfibrozil induced effects in S. aurata, in terms of behavior and/or oxidative stress responses. Oxidative damage was found at a concentration that is considered environmentally relevant, suggesting a potential of this pharmaceutical to impact fish populations.
Gold nanoparticles (AuNPs) are found in a wide range of applications and therefore expected to present increasing levels in the environment. There is however limited knowledge concerning the ...potential toxicity of AuNPs as well as their combined effects with other pollutants. Hence, the present study aimed to investigate the effects of AuNPs alone and combined with the pharmaceutical gemfibrozil (GEM) on different biological responses (behaviour, neurotransmission, biotransformation and oxidative stress) in one of the most consumed fish in southern Europe, the seabream Sparus aurata. Fish were exposed for 96 h to waterborne 40 nm AuNPs with two coatings – citrate and polyvinylpyrrolidone (PVP), alone or combined with GEM. Antioxidant defences were induced in liver and gills upon both AuNPs exposure. Decreased swimming performance (1600 μg.L−1) and oxidative damage in gills (4 and 80 μg.L−1) were observed following exposure to polyvinylpyrrolidone coated gold nanoparticles (PVP-AuNPs). Generally, accumulation of gold in fish tissues and deleterious effects in S. aurata were higher for PVP-AuNPs than for cAuNPs exposures. Although AuNPs and GEM combined effects in gills were generally low, in liver, they were higher than the predicted. The accumulation and effects of AuNPs showed to be dependent on the size, coating, surface charge and aggregation/agglomeration state of nanoparticles. Additionally, it was tissue' specific and dependent on the presence of other contaminants. Although, gold intake by humans is expected to not exceed the estimated tolerable daily intake, it is highly recommended to keep it on track due to the increasing use of AuNPs.
•Antioxidant defences of Sparus aurata were induced after the gold nanoparticles (AuNPs) exposure.•Polyvinylpyrrolidone coated AuNPs (PVP-AuNPs) induced more effects in the fish than citrate coated AuNPs (cAuNPs).•Decreased swimming performance and oxidative damage were detected after PVP-AuNPs exposure.•Gold accumulation and AuNPs toxicity were altered when fish were simultaneously exposed to AuNPs and gemfibrozil.
Widespread use of pharmaceuticals and suboptimal wastewater treatment have led to increased levels of these substances in aquatic ecosystems. Lipid-lowering drugs such as gemfibrozil, which are among ...the most abundant human pharmaceuticals in the environment, may have deleterious effects on aquatic organisms. We examined the genotoxicity of gemfibrozil in a fish species, the gilthead seabream (Sparus aurata), which is commercially important in southern Europe. Following 96-h waterborne exposure, molecular (erythrocyte DNA strand breaks) and cytogenetic (micronuclei and other nuclear abnormalities in cells) endpoints were measured. Gemfibrozil was positive in both endpoints, at environmentally relevant concentrations, a result that raises concerns about the potential genotoxic effects of the drug in recipient waters.
Cancers of the upper aerodigestive tract (UADT) are common forms of malignancy associated with tobacco and alcohol exposures, although human papillomavirus and nutritional deficiency are also ...important risk factors. While somatically acquired DNA methylation changes have been associated with UADT cancers, what triggers these events and precise epigenetic targets are poorly understood. In this study, we applied quantitative profiling of DNA methylation states in a panel of cancer-associated genes to a case-control study of UADT cancers. Our analyses revealed a high frequency of aberrant hypermethylation of several genes, including MYOD1, CHRNA3 and MTHFR in UADT tumors, whereas CDKN2A was moderately hypermethylated. Among differentially methylated genes, we identified a new gene (the nicotinic acetycholine receptor gene) as target of aberrant hypermethylation in UADT cancers, suggesting that epigenetic deregulation of nicotinic acetycholine receptors in non-neuronal tissues may promote the development of UADT cancers. Importantly, we found that sex and age is strongly associated with the methylation states, whereas tobacco smoking and alcohol intake may also influence the methylation levels in specific genes. This study identifies aberrant DNA methylation patterns in UADT cancers and suggests a potential mechanism by which environmental factors may deregulate key cellular genes involved in tumor suppression and contribute to UADT cancers.
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