Inmovilización de Kosakonia radicincitans como biofertilizante en alginato mediante gelificación iónica inversa

La agricultura enfrenta desafíos debido al crecimiento de la población, el calentamiento global y la crisis medioambiental. Los fertilizantes químicos utilizados actualmente en la agricultura afectan negativamente los ecosistemas, disminuyendo la productividad del suelo, alterando los productos agrícolas y contaminando el agua. Para abordar estos problemas, se están desarrollando tecnologías basadas en biofertilizantes. Los biofertilizantes contienen microorganismos beneficiosos que se agregan a los cultivos para estimular su crecimiento y productividad. Estos microorganismos pueden solubilizar fosfato, fijar nitrógeno, producir sustancias beneficiosas y controlar plagas y enfermedades. Una estrategia prometedora para mejorar los biofertilizantes es la encapsulación en biopolímeros, lo que protege los microorganismos y permite controlar su liberación en el suelo, aumentando su eficiencia y prolongando su efecto positivo en las plantas. En este trabajo se presentan los resultados de la inmovilización de Kosakonia radicincitans como bacteria promotora de crecimiento vegetal, en una matriz de alginato mediante la técnica de gelificación iónica inversa. Se presentan estudios de viabilidad en el tiempo y biodegradabilidad en suelos. Para ello, se dispersó el cultivo bacteriano con una solución estéril de CaCl2 0,4 M en una proporción (1:1) p/p. La suspensión se dejó caer en una solución de alginato de sodio al 2% en agitación. Luego, se consolidaron las cápsulas en una solución de CaCl2 0,2 M. Por último, se filtraron y se lavaron con agua destilada estéril. Las cápsulas se secaron en estufa a 35° C durante 48 h y a 25°C por convección forzada 6 m/s durante 24 h. La viabilidad se determinó antes y después del encapsulamiento, y posterior al secado, los resultados se expresaron como UFC/g de cápsulas, también se determinó el porcentaje de eficiencia de encapsulación (% EE). Los índices de biodegradabilidad se determinaron en suelos de vid a 28°C y 40°C con el tiempo. Los resultados obtenidos evidenciaron un % EE del 85,22 ± 2,44% para las cápsulas húmedas, en cuanto a la viabilidad luego del proceso de secado a los 7 días a 25°C y 35°C fue de 1 x 108 UFC/g y de 9,8 x 108 UFC/g de cápsulas secas, respectivamente. Las cápsulas secas a 25°C y 35°C, luego de sometidas a pruebas de biodegradabilidad a 40°C, no mostraron diferencias significativas a los 30 días. Sin embargo, estas cápsulas secas, probadas en suelos a 28°C 30 días, mostraron un % de biodegradabilidad del 55% y 65% respectivamente. Estos resultados permiten establecer que la temperatura de secado y la temperatura ambiente son factores importantes que influyen en el tiempo de permanencia del biofertilizante en el suelo

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV

Search for direct stau production in events with two hadronic tau-leptons in root s=13 TeV pp collisions with the ATLAS detector

A search for the direct production of the supersymmetric partners ofτ-leptons (staus) in final stateswith two hadronically decayingτ-leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of139fb−1, recorded with the ATLAS detector at the LargeHadron Collider at a center-of-mass energy of 13 TeV. No significant deviation from the expected StandardModel background is observed. Limits are derived in scenarios of direct production of stau pairs with eachstau decaying into the stable lightest neutralino and oneτ-lepton in simplified models where the two staumass eigenstates are degenerate. Stau masses from 120 GeV to 390 GeV are excluded at 95% confidencelevel for a massless lightest neutralino

Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

Early formation and recent starburst activity in the nuclear disk of the Milky Way

The nuclear disk is a dense stellar structure at the centre of the Milky Way, with a radius of ~150 pc (ref. 1). It has been a place of intense star formation in the past several tens of millions of years1-3, but its overall formation history has remained unknown2. Here, we report that the bulk of its stars formed at least 8 Gyr ago. After a long period of quiescence, a starburst event followed about 1 Gyr ago that formed roughly 5% of its mass within ~100 Myr, in what may arguably have been one of the most energetic events in the history of the Milky Way. Star formation continued subsequently on a lower level, creating a few per cent of the stellar mass in the past ~500 Myr, with an increased rate up to ~30 Myr ago. Our findings contradict the previously accepted paradigm of quasi-continuous star formation at the Galactic Centre4. The long quiescent phase agrees with the overall quiescent history of the Milky Way2,5 and suggests that our Galaxy's bar may not have existed until recently, or that gas transport through the bar was extremely inefficient during a long stretch of the Milky Way's life. Consequently, the central black hole may have acquired most of its mass already in the early days of the Milky Way

Measurements of long-range azimuthal anisotropies and associated Fourier coefficients for pp collisions at √s=5.02 and 13 TeV and p+Pb collisions at √sNN=5.02 TeV with the ATLAS detector

ATLAS measurements of two-particle correlations are presented for √s=5.02 and 13 TeV ppcollisions and for √sNN=5.02 TeV p+Pb collisions at the LHC. The correlation functions are measured as a function of relative azimuthal angle Δϕ, and pseudorapidity separation Δη, using charged particles detected within the pseudorapidity interval |η|2, is studied using a template fitting procedure to remove a “back-to-back” contribution to the correlation function that primarily arises from hard-scattering processes. In addition to the elliptic, cos (2Δϕ), modulation observed in a previous measurement, the pp correlation functions exhibit significant cos (3Δϕ) and cos (4Δϕ) modulation. The Fourier coefficients vn, n associated with the cos (nΔϕ) modulation of the correlation functions for n=2–4 are measured as a function of charged-particle multiplicity and charged-particle transverse momentum. The Fourier coefficients are observed to be compatible with cos (nϕ) modulation of per-event single-particle azimuthal angle distributions. The single-particle Fourier coefficients vn are measured as a function of charged-particle multiplicity, and charged-particle transverse momentum for n=2–4. The integrated luminosities used in this analysis are, 64nb−1 for the √s=13 TeV pp data, 170 nb−1 for the √ s = 5.02 TeV pp data, and 28 nb−1 for the √sNN = 5.02 TeV p+Pb data