233 research outputs found
DNA metabarcoding of trawling bycatch reveals diversity and distribution patterns of sharks and rays in the central Tyrrhenian Sea
Conservation and management of chondrichthyans are becoming increasingly important, as many species are particularly vulnerable to fishing activities, primarily as bycatch, which leads to incomplete catch reporting, potentially hiding the impact on these organisms. Here, we aimed at implementing an eDNA metabarcoding approach to reconstruct shark and ray bycatch composition from 24 hauls of a bottom trawl fishing vessel in the central Mediterranean. eDNA samples were collected through the passive filtration of seawater by simple gauze rolls encapsulated in a probe (the "metaprobe"), which already showed great efficiency in detecting marine species from trace DNA in the environment. To improve molecular taxonomic detection, we enhanced the 12S target marker reference library by generating sequences for 14 Mediterranean chondrichthyans previously unrepresented in public repositories. DNA metabarcoding data correctly identifies almost all bycaught species and detected five additional species not present in the net, highlighting the potential of this method to detect rare species. Chondrichthyan diversity showed significant association with some key environmental variables (depth and distance from the coast) and the fishing effort, which are known to influence demersal communities. As DNA metabarcoding progressively positions itself as a staple tool for biodiversity monitoring, we expect that its melding with opportunistic, fishery-dependent surveys could reveal additional distribution features of threatened and elusive megafauna
Aquivion® PFSA-based spray-freeze dried composite materials with SiO2 and TiO2 as hybrid catalysts for the gas phase dehydration of ethanol to ethylene in mild conditions
Aquivion PFSA resin, a perfluorinated ion-exchange polymer, has been used as a heterogeneous strong acid catalyst for a range of reactions; however, the activity of this material is limited due to the extremely low surface area of the polymer. In this paper we described the one-step synthesis of Aquivion® PFSA-based hybrid materials using heterocoagulation and spray-freeze-drying of sols containing the precursor of the active phases. The intimated encapsulation of different nano-oxides, such as TiO2 and SiO2 in the superacid resin matrix was easily obtained using this technique and compared with similar catalysts prepared by the impregnation conventional route. The approach led to the preparation of porous micro-granules characterised by a high homogeneity in the phase distribution and high surface area. The prepared materials were active and selective for the gas phase dehydration of ethanol to ethylene in mild conditions. The increase of the porosity improved the activity of the composites, compared to the pure Aquivion® PFSA, and allowed to reduce the amount of the superacid resin. Moreover, the type of encapsulated oxide, TiO2 or SiO2, modified the improved performance of the catalysts, having TiO2 the higher efficiency for ethanol conversion and selectivity in ethylene at very low temperature
Pd/Au based catalyst immobilization in polymeric nanofibrous membranes via electrospinning for the selective oxidation of 5-hydroxymethylfurfural
Innovative nanofibrous membranes based on Pd/Au catalysts immobilized via electrospinning onto different polymers were engineered and tested in the selective oxidation of 5- (hydroxymethyl)furfural in an aqueous phase. The type of polymer and the method used to insert the active phases in the membrane were demonstrated to have a significant effect on catalytic performance. The hydrophilicity and the glass transition temperature of the polymeric component are key factors for producing active and selective materials. Nylon-based membranes loaded with unsupported metal nanoparticles were demonstrated to be more efficient than polyacrylonitrilebased membranes, displaying good stability and leading to high yield in 2,5-furandicarboxylic acid. These results underline the promising potential of large-scale applications of electrospinning for the preparation of catalytic nanofibrous membranes to be used in processes for the conversion of renewable molecules
Influence of stabilisers on the catalytic activity of supported Au colloidal nanoparticles for the liquid phase oxidation of glucose to glucaric acid: understanding the catalyst performance from NMR relaxation and computational studies
Supported Au colloidal nanoparticles have been prepared in the presence of stabilising polymers, such as, PVA, PVP and PEG (polyvinylalcohol, polyvinylpyrrolidone, polyethylene glycol). The effect of the polymer to Au weight ratio was investigated, for the synthesis of Au nanoparticles with varying particle size and particle size distribution. By varying the polymer/Au wt/wt ratio, Au nanoparticles with mean diameters from 3 to 8 nm were synthesised. The synthesised Au catalysts were studied in the liquid phase oxidation of glucose to glucaric acid under alkaline conditions. We demonstrated that the choice of polymer and polymer to Au weight ratio, have an important influence in terms of catalytic activity and yield to glucaric acid. The highest yield to glucaric acid (22%) was obtained using Au–PVA catalysts. A strong deactivation was observed using Au catalysts. Further evaluation of the possible reasons for deactivation were investigated using experimental, computational and NMR relaxation studies
Their Day in Court: Assessing Guilty Plea Rates Among Terrorists
Individuals who are charged for traditional crimes are substantially more likely to plead guilty than individuals who are charged under the same statutes but who are officially involved in terrorism (Smith & Damphousse, 1998). Relying on a structural–contextual theory framework, a quantitative analysis not only confirmed that terrorists plead guilty more often than traditional offenders but that the defendant’s age and number of counts in the indictment are important predictors. Directions for future research are suggested.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
Polycarbonate-based ordered arrays of electrochemical nanoelectrodes obtained by e-beam lithography
Visual Information Alone Changes Behavior and Physiology during Social Interactions in a Cichlid Fish (Astatotilapia burtoni)
Social behavior can influence physiological systems dramatically yet the sensory
cues responsible are not well understood. Behavior of male African cichlid fish,
Astatotilapia burtoni, in their natural habitat suggests
that visual cues from conspecifics contribute significantly to regulation of
social behavior. Using a novel paradigm, we asked whether visual cues alone from
a larger conspecific male could influence behavior, reproductive physiology and
the physiological stress response of a smaller male. Here we show that just
seeing a larger, threatening male through a clear barrier can suppress dominant
behavior of a smaller male for up to 7 days. Smaller dominant males being
“attacked” visually by larger dominant males through a clear barrier
also showed physiological changes for up to 3 days, including up-regulation of
reproductive- and stress-related gene expression levels and lowered plasma
11-ketotestesterone concentrations as compared to control animals. The smaller
males modified their appearance to match that of non-dominant males when exposed
to a larger male but they maintained a physiological phenotype similar to that
of a dominant male. After 7 days, reproductive- and stress- related gene
expression, circulating hormone levels, and gonad size in the smaller males
showed no difference from the control group suggesting that the smaller male
habituated to the visual intruder. However, the smaller male continued to
display subordinate behaviors and assumed the appearance of a subordinate male
for a full week despite his dominant male physiology. These data suggest that
seeing a larger male alone can regulate the behavior of a smaller male but that
ongoing reproductive inhibition depends on additional sensory cues. Perhaps,
while experiencing visual social stressors, the smaller male uses an
opportunistic strategy, acting like a subordinate male while maintaining the
physiology of a dominant male
Substrate roughness influence on the order of nanografted Self-Assembled Monolayers
Adjacent patches of alkanethiol molecules whose chain lengths range from 11 to 15 carbon atoms are fabricated by nanografting within a Self-Assembled Monolayer matrix. Atomic Force Microscopy and Electrostatic Force Microscopy are employed to investigate their structural and electronic properties, highlighting the key role of the substrate roughness. In particular, the topographic phase signal allows to establish an odd–even dependence of the local stiffness versus the alkyl chain length, while the electrostatic force signal provides evidence that the conformational order versus the alkyl chain length follows an asymmetric parabolic trend induced by the substrate roughness
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