Characterization of scintillator screens under irradiation of low energy 133Cs ions

An imaging heavy ion beam probe (i-HIBP) diagnostic, for the simultaneous measurement of plasma density, magnetic field and electrostatic potential in the plasma edge, has been installed at ASDEX Upgrade. Unlike standard heavy ion beam probes, in the i-HIBP the probing (heavy) ions are collected by a scintillator detector, creating a light pattern or strike-line, which is then imaged by a camera. Therefore, a good characterization of the scintillator response is needed. Previous works focused on the scintillator behaviour against irradiation with light ions such as hydrogen and alpha particles. In this work we present the characterization of several scintillator screens - TG-Green (SrGa2S4:Eu2+), YAG-Ce (Y3Al5O12:Ce3+) and P11 (ZnS:Ag) - against irradiation with 133Cs+ ions, in an energy range between 5 and 70 keV and ion currents between 105 and 107 ions/(s·cm2). Three main properties of the scintillators have been studied: the ionolumenescence efficiency or yield, the linearity and the degradation as a function of the fluence. The highest yield was delivered by the TG-Green scintillator screen with > 8·103 photons/ion at 50 keV. All the samples showed a linear response with increasing incident ion flux. The degradation was quantified in terms of the fluence F1/2, which leads to a reduction of the emissivity by a factor of 2. TG-Green showed the lowest degradation with F1/2= 5.4·1014 ions/cm2. After the irradiation the samples were analyzed by Scanning Electron Microscopy (SEM), Rutherford Backscattering Spectrometry (RBS) and Particle Induced X-ray Emission (PIXE). No trace of Cs was found in the irradiated regions. These results indicate that, among the tested materials, TG-Green is the best candidate for the i-HIBP detector.This work received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 805162). G. Birkenmeier acknowledges funding from the Helmholtz Association under grant no. VHNG-1350. J. Galdon-Quiroga acknowledges funding from the Spanish Ministry of Science and Innovation under grant no. FJC2019-041092-I

The RecD2 helicase balances RecA activities

DNA helicases of the RecD2 family are ubiquitous. Bacillus subtilis RecD2 in association with the single-stranded binding protein SsbA may contribute to replication fork progression, but its detailed action remains unknown. In this work, we explore the role of RecD2 during DNA replication and its interaction with the RecA recombinase. RecD2 inhibits replication restart, but this effect is not observed in the absence of SsbA. RecD2 slightly affects replication elongation. RecA inhibits leading and lagging strand synthesis, and RecD2, which physically interacts with RecA, counteracts this negative effect. In vivo results show that recD2 inactivation promotes RecA–ssDNA accumulation at low mitomycin C levels, and that RecA threads persist for a longer time after induction of DNA damage. In vitro, RecD2 modulates RecA-mediated DNA strand-exchange and catalyzes branch migration. These findings contribute to our understanding of how RecD2 may contribute to overcome a replicative stress, removing RecA from the ssDNA and, thus, it may act as a negative modulator of RecA filament growth

Confined Pt11+ Water Clusters in a MOF Catalyze the Low‐Temperature Water–Gas Shift Reaction with both CO2 Oxygen Atoms Coming from Water

The synthesis and reactivity of single metal atoms in a low‐valence state bound to just water, rather than to organic ligands or surfaces, is a major experimental challenge. Herein, we show a gram‐scale wet synthesis of Pt11+ stabilized in a confined space by a crystallographically well‐defined first water sphere, and with a second coordination sphere linked to a metal–organic framework (MOF) through electrostatic and H‐bonding interactions. The role of the water cluster is not only isolating and stabilizing the Pt atoms, but also regulating the charge of the metal and the adsorption of reactants. This is shown for the low‐temperature water–gas shift reaction (WGSR: CO + H2O → CO2 + H2), where both metal coordinated and H‐bonded water molecules trigger a double water attack mechanism to CO and give CO2 with both oxygen atoms coming from water. The stabilized Pt1+ single sites allow performing the WGSR at temperatures as low as 50 °C.This work was supported by the MINECO (Spain) (Projects CTQ2016–75671–P, MAT2013 40823–R, MAT2016–81732–ERC, CTQ2017–86735–P, MAT2017–86992–R, MAT2017–82288–C2–1–P and Excellence Units “Severo Ochoa” and “Maria de Maeztu” SEV–2016–0683 and MDM–2015–0538) the Generalitat Valenciana (PROMETEOII/2014/004) and the Ministero dell’Istruzione, dell’Università e della Ricerca (Italy) and the Junta de Andalucía (FQM–195). M. M. and M.–A. R. C. thanks the MINECO for a predoctoral contract. Thanks are also extended to the Ramón y Cajal Program (E. V. R.–F., E. P. and J.–C. H.–G.) and the “Subprograma atracció de talent–contractes postdoctorals de la Universitat de Valencia” (J. F.–S.). M. L.–H. acknowledges the financial support from the Juan de la Cierva Fellowships Program of MINECO (IJCI–2014–19367)

Superficial Characteristics and Functionalization Effectiveness of Non-Toxic Glutathione-Capped Magnetic, Fluorescent, Metallic and Hybrid Nanoparticles for Biomedical Applications

An optimal design of nanoparticles suitable for biomedical applications requires proper functionalization, a key step in the synthesis of such nanoparticles, not only for subsequent crosslinking to biological targets and to avoid cytotoxicity, but also to endow these materials with colloidal stability. In this sense, a reliable characterization of the effectiveness of the functionalization process would, therefore, be crucial for subsequent bioconjugations. In this work, we have analyzed glutathione as a means to functionalize four of the most widely used nanoparticles in biomedicine, one of which is a hybrid gold-magnetic-iron-oxide nanoparticle synthetized by a simple and novel method that we propose in this article. We have analyzed the colloidal characteristics that the glutathione capping provides to the different nanoparticles and, using information on the Z-potential, we have deduced the chemical group used by glutathione to link to the nanoparticle core. We have used electron microscopy for further structural and chemical characterization of the nanoparticles. Finally, we have evaluated nanoparticle cytotoxicity, studying cell viability after incubation with different concentrations of nanoparticles, showing their suitability for biomedical applications

Ampliaciones del rango de distribución de algunas especies de anfibios y reptiles en elsuroccidente de Ecuador

We present new localities of four species of amphibians and reptiles from foothill and high - Andean areas of the province of El Oro, southwestern Ecuador. These records significantly expand the global distributional ranges of Nymphargus buenaventura, Gastrotheca lateonata, Anolis lyra and Pliocercus euryzonus.Presentamos nuevas localidades para cuatro especies de anfibios y reptiles en áreas piemontanas y altoandinas en la provincia de El Oro, suroccidente de Ecuador. Estos registros expanden significativamente los rangos de distribución globales de Nymphargus buenaventura, Gastrotheca lateonata, Anolis lyra y Pliocercus euryzonus

Los Poyos del Molinillo (Frigiliana): new site of the Bronze Age in the East Axarquía (Málaga, Andalucía)

En este trabajo damos a conocer un nuevo yacimiento descubierto recientemente en el municipio de Frigiliana. La delimitación del área denominada Los Poyos del Molinillo permitió definir la existencia de un poblado y una covacha con restos de una inhumación. El estudio de los materiales arqueológicos, que incluye cerámica, piezas metálicas o elementos de molturación, o la datación AMS obtenida, permiten adscribir el yacimiento a la Edad del Bronce y ampliar el conocimiento de esta etapa en la Axarquía oriental (Málaga, Andalucía).In this work we present a new site recently discovered in the Frigiliana municipality (Málaga). The spatial delimitation of the so called Los Poyos del Molinillo area let us define a Bronze age settlement and an inhumation burial cave. The archaeological record includes ceramic, metallic items or grinding elements, all of them belonging to the Bronze Age, as well as an AMS Radiocarbon data. This site extends the knowledge about this period in the Eastern Axarquía (Málaga, Andalucía)

Patchiness and Demographic Noise in Three Ecological Examples

Understanding the causes and effects of spatial aggregation is one of the most fundamental problems in ecology. Aggregation is an emergent phenomenon arising from the interactions between the individuals of the population, able to sense only -at most- local densities of their cohorts. Thus, taking into account the individual-level interactions and fluctuations is essential to reach a correct description of the population. Classic deterministic equations are suitable to describe some aspects of the population, but leave out features related to the stochasticity inherent to the discreteness of the individuals. Stochastic equations for the population do account for these fluctuation-generated effects by means of demographic noise terms but, owing to their complexity, they can be difficult (or, at times, impossible) to deal with. Even when they can be written in a simple form, they are still difficult to numerically integrate due to the presence of the "square-root" intrinsic noise. In this paper, we discuss a simple way to add the effect of demographic stochasticity to three classic, deterministic ecological examples where aggregation plays an important role. We study the resulting equations using a recently-introduced integration scheme especially devised to integrate numerically stochastic equations with demographic noise. Aimed at scrutinizing the ability of these stochastic examples to show aggregation, we find that the three systems not only show patchy configurations, but also undergo a phase transition belonging to the directed percolation universality class.Comment: 20 pages, 5 figures. To appear in J. Stat. Phy