2,283 research outputs found
On the removal of s-triazine herbicides from waters using commercial low-cost granular carbons
The adsorption capacities of three low-cost granular active carbons, used in a water treatment facility for the removal of the triazine herbicides propazine, prometryn and prometon, was evaluated. Kinetic studies showed that the three carbon samples used could be suitable in practice for the treatment of moderate contents of the herbicides in contaminated waters. The apparent adsorption rate constants were calculated. Equilibrium studies showed that the data fit the Frumkin isotherm. The results show that in the adsorption process there are repulsive lateral interactions that depend mainly on the adsorbate molecules rather than the nature or distribution of the adsorption sites. Such lateral interactions seem to be established mainly between the isopropyl groups of adjacent molecules, being of the same order for the three molecules
The use of stable isotope ratio analysis to trace European sea bass (D. labrax) originating from different farming systems
This study aimed to determine whether isotopic ratio mass spectrometry (IRMS) can discriminate farmed European sea bass according to different farming systems and geographic origins. Dicentrarchus labrax of commercial size from three different rearing systems (concrete tank inland, sea cages, and extensive methods in valleys or salt works) were collected at the trading period (autumn\u2013winter). For each farming type, different locations spread over Italy were monitored. Once the fish were harvested, the muscle and feed were sampled. For both muscle and feed, \u3b413C and \u3b415N were measured by continuous flow elemental analyzer isotope ratio mass spectrometry (CF-EA-IRMS) with the goal of discriminating samples based on the rearing system. Additional \u3b42H and \u3b418O measurements of fish samples were performed by continuous flow total combustion elemental analyzer isotope ratio mass spectrometry (CF-TC/EA-IRMS) to track the geographical origin. The measurements of \u3b413C and \u3b415N made it possible to discriminate cultured sea bass from different farming systems (extensive vs. intensive) reared at different geographical sites in Italy. Additional information was obtained from \u3b418O and \u3b42H, which enabled the geographical areas of origin of the sea bass farmed extensively and intensively (in cages) to be distinguished
Intermediate snowpack melt-out dates guarantee the highest seasonal grasslands greening in the Pyrenees
In mountain areas, the phenology and productivity of grassland are closely related to snow dynamics. However, the influence that snow melt timing has on grassland growing still needs further attention for a full understanding, particularly at high spatial resolution. Aiming to reduce this knowledge gap, this work exploits 1 m resolution snow depth and Normalized Difference Vegetation Index observations acquired with an Unmanned Aerial Vehicle at a sub-alpine site in the Pyrenees. During two snow seasons (2019–2020 and 2020–2021), 14 NDVI and 17 snow depth distributions were acquired over 48 ha. Despite the snow dynamics being different in the two seasons, the response of grasslands greening to snow melt-out exhibited a very similar pattern in both. The NDVI temporal evolution in areas with distinct melt-out dates reveals that sectors where the melt-out date occurs in late April or early May (optimum melt-out) reach the maximum vegetation productivity. Zones with an earlier or a later melt-out rarely reach peak NDVI values. The results obtained in this study area, suggest that knowledge about snow depth distribution is not needed to understand NDVI grassland dynamics. The analysis did not reveal a clear link between the spatial variability in snow duration and the diversity and richness of grassland communities within the study area
Phenotypic Characteristics and Copy Number Variants in a Cohort of Colombian Patients with VACTERL Association
VACTERL association (OMIM 192350) is a heterogeneous clinical condition characterized by congenital structural defects that include at least 3 of the following features: vertebral abnormalities, anal atresia, heart defects, tracheoesophageal fistula, renal malformations, and limb defects. The nonrandom occurrence of these malformations and some familial cases suggest a possible association with genetic factors such as chromosomal alterations, gene mutations, and inherited syndromes such as Fanconi anemia (FA). In this study, the clinical phenotype and its relationship with the presence of chromosomal abnormalities and FA were evaluated in 18 patients with VACTERL association. For this, a G-banded karyotype, array-comparative genomic hybridization, and chromosomal fragility test for FA were performed. All patients (10 female and 8 male) showed a broad clinical spectrum: 13 (72.2%) had vertebral abnormalities, 8 (44.4%) had anal atresia, 14 (77.8%) had heart defects, 8 (44.4%) had esophageal atresia, 10 (55.6%) had renal abnormalities, and 10 (55.6%) had limb defects. Chromosomal abnormalities and FA were ruled out. In 2 cases, the finding of microalterations, namely del(15)(q11.2) and dup(17)(q12), explained the phenotype; in 8 cases, copy number variations were classified as variants of unknown significance and as not yet described in VACTERL. These variants comprise genes related to important cellular functions and embryonic development
Very high energy particle acceleration powered by the jets of the microquasar SS 433
SS 433 is a binary system containing a supergiant star that is overflowing
its Roche lobe with matter accreting onto a compact object (either a black hole
or neutron star). Two jets of ionized matter with a bulk velocity of
extend from the binary, perpendicular to the line of sight, and
terminate inside W50, a supernova remnant that is being distorted by the jets.
SS 433 differs from other microquasars in that the accretion is believed to be
super-Eddington, and the luminosity of the system is erg
s. The lobes of W50 in which the jets terminate, about 40 pc from the
central source, are expected to accelerate charged particles, and indeed radio
and X-ray emission consistent with electron synchrotron emission in a magnetic
field have been observed. At higher energies (>100 GeV), the particle fluxes of
rays from X-ray hotspots around SS 433 have been reported as flux
upper limits. In this energy regime, it has been unclear whether the emission
is dominated by electrons that are interacting with photons from the cosmic
microwave background through inverse-Compton scattering or by protons
interacting with the ambient gas. Here we report TeV -ray observations
of the SS 433/W50 system where the lobes are spatially resolved. The TeV
emission is localized to structures in the lobes, far from the center of the
system where the jets are formed. We have measured photon energies of at least
25 TeV, and these are certainly not Doppler boosted, because of the viewing
geometry. We conclude that the emission from radio to TeV energies is
consistent with a single population of electrons with energies extending to at
least hundreds of TeV in a magnetic field of ~micro-Gauss.Comment: Preprint version of Nature paper. Contacts: S. BenZvi, B. Dingus, K.
Fang, C.D. Rho , H. Zhang, H. Zho
Measurement of the Crab Nebula Spectrum Past 100 TeV with HAWC
We present TeV gamma-ray observations of the Crab Nebula, the standard
reference source in ground-based gamma-ray astronomy, using data from the High
Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory. In this analysis we use
two independent energy-estimation methods that utilize extensive air shower
variables such as the core position, shower angle, and shower lateral energy
distribution. In contrast, the previously published HAWC energy spectrum
roughly estimated the shower energy with only the number of photomultipliers
triggered. This new methodology yields a much improved energy resolution over
the previous analysis and extends HAWC's ability to accurately measure
gamma-ray energies well beyond 100 TeV. The energy spectrum of the Crab Nebula
is well fit to a log parabola shape with emission up to at least 100 TeV. For the first
estimator, a ground parameter that utilizes fits to the lateral distribution
function to measure the charge density 40 meters from the shower axis, the
best-fit values are
=(2.350.04)10 (TeV cm
s), =2.790.02, and
=0.100.01. For the second estimator, a neural
network which uses the charge distribution in annuli around the core and other
variables, these values are
=(2.310.02)10 (TeV cm
s), =2.730.02, and
=0.060.010.02. The first set of uncertainties are statistical;
the second set are systematic. Both methods yield compatible results. These
measurements are the highest-energy observation of a gamma-ray source to date.Comment: published in Ap
Valorization of grape stems
The wine industry produces large amounts of grape stem byproducts, which have been described as a natural source of polyphenols. In the present study, an extract from grape stems was evaluated for its antioxidant and antimicrobial activities in model wine to determine its potential capacity to replace and/or reduce SO2 in winemaking. Additionally, its possible effects on aroma were studied.
Grape stem extract (STE) showed high antioxidant activity and it can be proposed as an energetic antioxidant. Its antimicrobial activity was compared to that of SO2. STE showed a lower inhibitory effect than SO2 for Saccharomyces cerevisiae, Hanseniaspora uvarum, Dekkera bruxellensis and Pediococcus damnosus whereas STE seems to be more efficient against Candida stellata and Botryotinia fuckeliana. GC–olfactometry analysis of STE showed that its most important odorants are naturally present in wines, and thus olfactometric profile modifications in wine, after STE addition, could appear quantitatively but not qualitatively.
It can be concluded that grape stems are compounds with a low sourcing cost, high antioxidant activity and good antimicrobial properties.Ciencias de la AlimentaciónFarmaciaMedicin
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