•The slowest step of the acetone synthesis from ethanol follows the MVK mechanism.•The easier the vacancy generation is, the higher the acetone synthesis rate will be.•Nanostructured CeO2 based ...catalysts were used as tools to describe the MVK mechanism.
Nanostructured CeO2 based catalysts were employed as tools to shed light on the mechanism of the acetone synthesis from ethanol. The oxides were characterized using HRTEM, EPR, and other techniques. Rates of ethanol consumption and products formation were measured at differential conditions. The catalysts prepared employing Ce(NO3)3 generate nanocubes, whereas when (NH4)2Ce(NO3)6 is used, nanopolyhedral particles are synthesised. The later forms O vacancies more easily. This property enhances when Ag is added to the nanopolyhedral catalyst. The correlation between the catalytic behaviour and the nanocatalysts`s physicochemical properties showed that O vacancies participate as Brønsted basic sites in the acetaldehyde synthesis and that the easier the O vacancies generation, the higher the rate of the acetone synthesis is. The O abstraction from the CeO2 lattice by acetaldehyde (Mars and Van Krevelen mechanism) is the slowest step of the acetone synthesis from ethanol, showing that this synthesis exhibits a relevant redox characteristic.
Naproxen (Nap), a non‐steroidal anti‐inflammatory drug, and 5‐fluorouracil (5FU), an anticancer drug, were easily incorporated into a polyurea xerogel. Polyureas (PUr) were synthesized by one pot ...reaction via sol–gel chemistry. Soft segments were based on polyetheramine‐PEO and hard segments were based on a hexamethylene diisocyanate trimer (HDI). The final materials were characterized by Fourier transform infrared (FTIR) spectroscopy, small‐angle X‐ray scattering (SAXS), and differential scanning calorimetry (DSC). Polyurea can assume many forms revealing its versatility in terms of produced shapes. In good agreement with FTIR, SAXS studies showed a microphase separated structure arising from inter‐hard‐domain spacings, which remains unchanged after incorporation of the drugs. DSC analysis demonstrated that the PEO chain mobility was poorly affected after the drugs incorporation due to the solvation of the drugs through the network. The water uptake and the amount of drug released agree well, playing an important role for controlled Nap and 5FU release. This work opens positive perspectives for ocular drug delivery and wound management, due to the easy processability of the xerogel, which has high feasibility to be moldable as pharmaceutical devices for contact lenses and transdermal patches purposes containing distinct therapeutic agents.
The successful dual‐drug release highlights the polyurea xerogel as a versatile carrier to combine anti‐inflamatory and anticancer drugs into a single polymer matrix, opening new oportunities to develop functional materials containing different species for optical, health and environmental applications.
We present the first quantitative detection of large-scale filamentary structure at z NOT approximately equal to 0.7 in the large cosmological volume probed by the VIMOS Public Extragalactic ...Redshift Survey (VIPERS). We use simulations to show the capability of VIPERS to recover robust topological features in the galaxy distribution, in particular the filamentary network. We then investigate how galaxies with different stellar masses and stellar activities are distributed around the filaments, and find a significant segregation, with the most massive or quiescent galaxies being closer to the filament axis than less massive or active galaxies. The signal persists even after downweighting the contribution of peak regions. Our results suggest that massive and quiescent galaxies assemble their stellar mass through successive mergers during their migration along filaments towards the nodes of the cosmic web. On the other hand, low-mass star-forming galaxies prefer the outer edge of filaments, a vorticity-rich region dominated by smooth accretion, as predicted by the recent spin alignment theory. This emphasizes the role of large-scale cosmic flows in shaping galaxy properties.
We present a direct comparison between the observed star formation rate functions (SFRFs) and the state-of-the-art predictions of semi-analytic models (SAMs) of galaxy formation and evolution. We use ...the PACS Evolutionary Probe Survey and Herschel Multi-tiered Extragalactic Survey data sets in the COSMOS and GOODS-South fields, combined with broad-band photometry from UV to sub-mm, to obtain total (IR+UV) instantaneous star formation rates (SFRs) for individual Herschel galaxies up to z ∼ 4, subtracted of possible active galactic nucleus (AGN) contamination. The comparison with model predictions shows that SAMs broadly reproduce the observed SFRFs up to z ∼ 2, when the observational errors on the SFR are taken into account. However, all the models seem to underpredict the bright end of the SFRF at z ≳ 2. The cause of this underprediction could lie in an improper modelling of several model ingredients, like too strong (AGN or stellar) feedback in the brighter objects or too low fallback of gas, caused by weak feedback and outflows at earlier epochs.
A new species of Potamotrygon is described from the Rio Negro drainage, Amazonas, Brazil. In spite of being cited or pictured several times in the scientific and aquarium fish literature since the ...19th Century, it had been misidentified and still lacked a scientific name. Potamotrygon wallacei, n. sp., is diagnosed by the following characters: dorsal surface of disc light brown, with black irregularly-shaped vermiculate markings forming an amphora- or Ω-shaped figure on mid-disc, delimiting light brown reniform areas at disc center, and with subcircular light brown ocellate markings on disc margins; small body size (smallest known Potamotrygon species; largest examined specimen measured 310 mm DW); dorsal spines on tail usually rather low, without broad bases, in one to rarely three irregular rows, but extending posteriorly only to tail mid-length and not to caudal stings, with altogether relatively few spines; denticles on posterior mid-disc and tail base Y-shaped, with a central, anterior, bulbous cusp and usually two posterior pairs of smaller, rounded cusps; and single (anterior) angular cartilage. The new species is similar to P. orbignyi and other "reticulated" species in having a single (anterior) angular cartilage and in the color pattern of the tail, but is easily distinguished based on its size, dorsal tail spine arrangement, and specific details of color pattern.
Temporal trends in the recovery of exploited species in marine protected areas (MPAs) are useful for a proper assessment of the efficacy of protection measures. The effects of protection on the fish ...assemblages of the sublittoral rocky reefs in the "Penisola del Sinis-Isola di Mal di Ventre" MPA (W. Sardinia, Italy) were evaluated using a multi-year series of data. Four surveys, conducted 7, 10, 13 and 15 years after the area was designated as an MPA and carried out in the period spanning June and July, were used to estimate the abundance and biomass of commercial species. The surveys were carried out in zones with decreasing levels of fishing restrictions within the MPA (zones A, B, C) and in unprotected zones (OUT1 and OUT2), and underwater video visual census techniques were used. Protected zones only occasionally showed higher levels of abundance or biomass, and the trajectories of those metrics were not consistent across the years. In addition, the zone with the highest level of protection (zone A) never presented levels of abundance and biomass higher than those in zones B and C. This study shows that even 15 years after designation, protection has had no appreciable effect in the MPA studied. It is argued that this is emblematic of several shortcomings in the planning, regulation and enforcement frameworks of the MPA.
We explore the accuracy of the clustering-based redshift estimation proposed by Ménard et al. when applied to VIMOS Public Extragalactic Redshift Survey (VIPERS) and Canada–France–Hawaii Telescope ...Legacy Survey (CFHTLS) real data. This method enables us to reconstruct redshift distributions from measurement of the angular clustering of objects using a set of secure spectroscopic redshifts. We use state-of-the-art spectroscopic measurements with i
AB < 22.5 from the VIPERS as reference population to infer the redshift distribution of galaxies from the CFHTLS T0007 release. VIPERS provides a nearly representative sample to a flux limit of i
AB < 22.5 at a redshift of >0.5 which allows us to test the accuracy of the clustering-based redshift distributions. We show that this method enables us to reproduce the true mean colour–redshift relation when both populations have the same magnitude limit. We also show that this technique allows the inference of redshift distributions for a population fainter than the reference and we give an estimate of the colour–redshift mapping in this case. This last point is of great interest for future large-redshift surveys which require a complete faint spectroscopic sample.
Anthropogenic debris in the environment affects many species that accidentally ingest it. The aim of this study is to evaluate the quantity and composition of marine litter ingested by loggerheads in ...Sardinia, thus supplying for the lack of data in the existing literature for this area. Seventeen of the 121 (14.04%) monitored turtles presented debris in their digestive tracts. Litter in faecal pellet of alive individuals (n = 91) and in gastro-intestinal contents of dead ones (n = 30) was categorized, counted and weighed. User plastic was the main category of ingested debris with a frequency of occurrence of 13.22% of the total sample, while sheet (12.39%) and fragments (9.09%) were the most relevant sub-categories. This study highlights for the first time the incidence of litter in alive turtles in Sardinia. This contribution improves the knowledge about marine litter interaction on Caretta caretta as bio-indicator. Results will be useful for the Marine Strategy implementation.
•This is the first study on interaction between sea turtles and litter in Sardinia.•White sheet items are the most ingested plastic sub-category.•This study will be useful for the implementation of the MSFD monitoring programs.•Our results support the choice of C. caretta as bio-indicator for Mediterranean.
ABSTRACT In this Letter we compare the abundance of the member galaxies of a rich, nearby (z = 0.09) galaxy cluster, Abell 2142, with that of halos of comparable virial mass extracted from sets of ...state-of-the-art numerical simulations, both collisionless at different resolutions and with the inclusion of baryonic physics in the form of cooling, star formation, and feedback by active galactic nuclei. We also use two semi-analytical models to account for the presence of orphan galaxies. The photometric and spectroscopic information, taken from the Sloan Digital Sky Survey Data Release 12 database, allows us to estimate the stellar velocity dispersion of member galaxies of Abell 2142. This quantity is used as proxy for the total mass of secure cluster members and is properly compared with that of subhalos in simulations. We find that simulated halos have a statistically significant ( 7 sigma confidence level) smaller amount of massive (circular velocity above 200 km s − 1 ) subhalos, even before accounting for the possible incompleteness of observations. These results corroborate the findings from a recent strong lensing study of the Hubble Frontier Fields galaxy cluster MACS J0416 and suggest that the observed difference is already present at the level of dark matter (DM) subhalos and is not solved by introducing baryonic physics. A deeper understanding of this discrepancy between observations and simulations will provide valuable insights into the impact of the physical properties of DM particles and the effect of baryons on the formation and evolution of cosmological structures.
Recent research on the use of physical mixtures In2O3-ZrO2 has raised interesting questions as to how their combination enhances catalytic activity and selectivity. Specifically, the relationship ...between oxygen diffusion and defect formation and the epitaxial tension in the mixture should be further investigated. In this study, we aim to clarify some of these relationships through a molecular dynamics approach. Various potentials for the two oxides are compared and selected to describe the physical mixture of In2O3 and ZrO2. Different configurations of each single crystal and their physical mixture are simulated, and oxygen defect formation and diffusion are measured and compared. Significant oxygen defect formation is found in both crystals. In2O3 seems to be stabilized by the mixture, while ZrO2 is destabilized. Similar results were found for the ZrO2 doping with In and ln2O3 doping with Zr. The results explain the high activity and selectivity catalyst activity of the mixture for the production of isobutylene from ethanol.
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