Dilution versus pollution in watercourses affected by acid mine drainage: a graphic model for the Iberian Pyrite Belt (SW Spain)

The aim of this study was to chemically characterize the water quality impacts of the 88 acid mine drainage (AMD) generating mines in the Spanish sector of the Iberian Pyrite Belt (IPB). This was necessary because the Water Framework Directive of the European Union and the hydrological plans of the Tinto, Odiel, and Piedras river basins require that water quality be improved enough to allow at least some of the rivers in the IPB to sustain healthy fish populations by 2027. The results indicate a clear decrease in metals, arsenic, and sulfate concentrations and increased pH between the AMD-sources and the river channels.info:eu-repo/semantics/publishedVersio

Graphene-based perfect optical absorbers harnessing guided mode resonances

We numerically and experimentally investigate graphene-based optical absorbers that exploit guided mode resonances (GMRs) achieving perfect absorption over a bandwidth of few nanometers (over the visible and near-infrared ranges) with a 40-fold increase of the monolayer graphene absorption. We analyze the influence of the geometrical parameters on the absorption rate and the angular response for oblique incidence. Finally, we experimentally verify the theoretical predictions in a one-dimensional, dielectric grating and placing it near either a metallic or a dielectric mirror

Graphene-based absorber exploiting guided mode resonances in one-dimensional gratings

A one-dimensional dielectric grating, based on a simple geometry, is proposed and investigated to enhance light absorption in a monolayer graphene exploiting guided mode resonances. Numerical findings reveal that the optimized configuration is able to absorb up to 60% of the impinging light at normal incidence for both TE and TM polarizations resulting in a theoretical enhancement factor of about 26 with respect to the monolayer graphene absorption (about 2.3%). Experimental results confirm this behaviour showing CVD graphene absorbance peaks up to about 40% over narrow bands of few nanometers. The simple and flexible design paves the way for the realization of innovative, scalable and easy-to-fabricate graphene-based optical absorbers

Ligand exchange in gold-coated FePt nanoparticles

In this work, we present the magnetic properties of gold-coated FePt nanoparticles and the study of stable aqueous dispersions of FePt@Au and FePt synthesized after ligand exchange with mercaptoundecanoic acid. The particle size determined from transmission electron microscopy (TEM) micrographs goes from 4 nm for the uncoated nanoparticles to a maximum of 10 nm for the gold-coated ones indicating that the thickness of the shell ranges from 1 to 3 nm. The magnetic characterization consists in hysteresis cycles at 10 and 300 K. The results show that, at low field and room temperature, the magnetic behavior of uncoated and coated nanoparticles are surprisingly quite similar. Because the gold-coated nanoparticles keep the magnetic properties of FePt and the presence of gold improves the functionalization of nanoparticles, the system is suitable for biological application. Mercaptoundecanoic ligand transfer was used to render water stable nanoparticles in a wide pH range. Transmission electron microscopy and dynamic light scattering (DLS) results show the nanoparticles slightly agglomerate after ligand exchange. Fourier transform infrared spectroscopy results suggest that thiol binds to the gold atoms of the surface

Carbazole and simplified derivatives: Novel tools toward β-adrenergic receptors targeting

β-Adrenergic receptors (β-ARs) are G protein-coupled receptors involved in important physiological and pathological processes related to blood pressure and cardiac activity. The inhibition of cardiac β1-ARs could be beneficial in myocardial hypertrophy, ischemia and failure. Several carbazole-based compounds have been described as promising β-blockers. Herein, we investigate the capability of a carbazole derivative and three simplified indole analogs to interact with the active binding site of β1-AR by molecular docking studies. In the light of the obtained results, our compounds were tested by biological assays in H9c2 cardiomyocytes exposed to isoproterenol (ISO) to confirm their potential as β1-blockers agents, and two of them (8 and 10) showed interesting and promising properties. In particular, these compounds were effective against ISO-dependent in vitro cardiac hypertrophy, even at concentrations lower than the known β-AR antagonist propranolol. Overall, the data suggest that the indole derivatives 8 and 10 could act as potent β1-blockers and, active at low doses, could elicit limited side effects

Synthesis and characterization of FePt/Au core-shell nanoparticles

In this work, the structural and magnetic properties of the gold- coated FePt nanoparticles synthesized from high- temperature solution phase are presented. The amount of gold was optimized to obtain most of the FePt particles coated. The particle diameter increases from 4 to 10 nm as observed by TEM. The magnetic properties are largely affected by the coating. At low temperature, the coercive. field Hc of the coated nanoparticles decreases about three times respect to the uncoated and the blocking temperature reduces to the half. The changes of the magnetic behavior are discussed in terms of the effect of the gold atoms at the FePt core surface