Polymer-solvent interaction parameters of SBS rubbers by inverse gas chromatography measurements

The solubility parameters of two SBS commercial rubbers with different structures (lineal and radial), and with slightly different styrene content have been determined by inverse gas chromatography technique. The Flory–Huggins interaction parameters of several polymer–solvent mixtures have also been calculated. The influence of the polymer composition, the solvent molecular weight and the temperature over these parameters have been discussed; besides, these parameters have been compared with previous ones, obtained by intrinsic viscosity measurements. From the Flory–Huggins interaction parameters, the infinite dilution activity coefficients of the solvents have been calculated and fitted to the well-known NRTL model. These NRTL binary interaction parameters have a great importance in modelling the separation steps in the process of obtaining the rubber

Adsorption of representative pharmaceutical compounds from hospital wastewater by carbon materials

Pharmaceuticals are a class of emerging environmental contaminants that are extensively and increasingly being used in human and veterinary medicine. The worldwide consumption of these substances has increased in both hospitals and households, which represents a major concern in terms of their potential harmful effects on the environment and human health [1]. Thus, fluoroquinolone antibiotics are widely used in human medicine and animal breeding for preventing and curing diseases. Ciprofloxacin is a wide-spectrum fluoroquinolone antibiotic extensively used in the world, which can generate high contributions to public sewers. Meanwhile, carbamazepine, one of the most widely prescribed psychoactive drugs, shows important endocrine disrupting effects and it is frequently detected in high concentrations in both WWTPs effluents and river water. Because of the removal efficiency of these compounds in the conventional wastewater treatment plants is not complete (ranging from 7-8% for carbamazepine), it is necessary the implementation of tertiary technologies in order to achieve WWTPs effluents with a better quality. Adsorption onto carbon materials has proven as an efficient treatment in the removal of a broad spectrum of micro-pollutants. This work has been focused on the study of equilibrium adsorption of carbamazepine (CBZ) and ciprofloxacin (CPX) from ultrapure water at 30 ºC using carbonaceous materials. Commercial carbon materials (AC-F400 activated carbon, multi-walled carbon nanotubes, MWNT, and carbon nanofibers, CNF) and lab-synthesized activated carbons from peach stones (AC-PS) and rice husk (AC-RH) as precursors have been used. Moreover, carbon adsorbents have been used to treat a real hospital wastewater containing 55 different pharmaceutical compounds. Among them, both CBZ and CPX were found at concentrations of 162.55 and \u3e 40 ng.L-1, respectively. The removal efficiency of quality macroscopic parameters (Total Organic Carbon concentration, TOC, Total Nitrogen concentration, TN, carbonates, CO32-, and aromaticity) and each of the pharmaceuticals contained in the wastewater was evaluated. Large adsorption capacities of CBZ and CPX (around 240 and 200 mg.g-1) were found in 4 hours, using adsorbent doses ranging from 2-3 g.L-1, natural pH, temperature of 30 ºC and stirring rate of 250 rpm. In addition, competitive adsorption experiments using both pollutants in ultrapure water have been performed. The bi-component adsorption systems were reasonably well-fitted by the extended Freundlich model equation. In the treatment of the hospital wastewater, a maximum TOC reduction of 96.5% ([TOC]0 = 110 mg L-1) was achieved by adsorption onto AC-RH activated carbon, since all the studied macroscopic parameters were too efficiently removed. Moreover, by the adsorption treatment, the complete disappearance of all the pharmaceutical compounds (except two of them) was observed. References [1] S. Ortiz de García, G. Pinto Pinto, P. García Encina, R. Irusta Mata, Consumption and occurrence of pharmaceutical and personal care products in the aquatic environment in Spain, Sci. Total Environ. 444 (2013) 451–465

Electrochemical synthesis and magnetic properties of MFe_2O_4 (M = Fe, Mn, Co, Ni) nanoparticles for potential biomedical applications

In this study, we evaluate the magnetic properties and cytotoxic effect of magnetic nanoparticles (MNPs) based on magnetite and Mn, Co and Ni ferrites, obtained by electrochemical synthesis. These nanoparticles have almost spherical shape and an mode size of 9 +/- 1 nm. The electrochemical synthesis produces a single crystallographic phase with a spinel-like structure in all cases. Magnetization saturation at room temperature varies with the composition of the ferrites from M_S (Fe_3O_4) > M_S (MnFe_2O_4) > M_S (CoFe_2O_4) > M_S (NiFe_2O_4). Ferrite MNPs present low magnetic remanence indicating a superparamagnetic-like response at room temperature. However, the different values of magnetic anisotropy and size produce variations in the values of coercivity and susceptibility of the ferrite MNPs. The cytotoxicity of the different ferrites was evaluated by internalizing MNP in HeLa cancer cells. Although magnetite and Mn ferrite present low toxicity for all the concentrations studied, significant cytotoxic effect were observed when incubating the cells with high concentration of Co and Ni ferrites

Metasurface Antennas: New Models, Applications and Realizations

This paper presents new designs, implementation and experiments of metasurface (MTS) antennas constituted by subwavelength elements printed on a grounded dielectric slab. These antennas exploit the interaction between a cylindrical surface wave (SW) wavefront and an anisotropic impedance boundary condition (BC) to produce an almost arbitrary aperture field. They are extremely thin and excited by a simple in-plane monopole. By tailoring the BC through the shaping of the printed elements, these antennas can be largely customized in terms of beam shape, bandwidth and polarization. In this paper, we describe new designs and their implementation and measurements. It is experimentally shown for the first time that these antennas can have aperture efficiency up to 70%, a bandwidth up to 30%, they can produce two different direction beams of high-gain and similar beams at two different frequencies, showing performances never reached before

Self-Assembly of Au-Fe3O4 Hybrid Nanoparticles Using a Sol–Gel Pechini Method

The Pechini method has been used as a synthetic route for obtaining self-assembling magnetic and plasmonic nanoparticles in hybrid silica nanostructures. This manuscript evaluates the influence of shaking conditions, reaction time, and pH on the size and morphology of the nanostructures produced. The characterization of the nanomaterials was carried out by transmission electron microscopy (TEM) to evaluate the coating and size of the nanomaterials, Fourier-transform infrared spectroscopy (FT-IR) transmission spectra to evaluate the presence of the different coatings, and thermogravimetric analysis (TGA) curves to determine the amount of coating. The results obtained show that the best conditions to obtain core–satellite nanostructures with homogeneous silica shells and controlled sizes (<200 nm) include the use of slightly alkaline media, the ultrasound activation of silica condensation, and reaction times of around 2 h. These findings represent an important framework to establish a new general approach for the click chemistry assembling of inorganic nanostructures

High-dose exposure to polymer-coated iron oxide nanoparticles elicits autophagy-dependent ferroptosis in susceptible cancer cells

Ferroptosis, a form of iron-dependent, lipid peroxidation-driven cell death, has been extensively investigated in recent years, and several studies have suggested that the ferroptosis-inducing properties of iron-containing nanomaterials could be harnessed for cancer treatment. Here we evaluated the potential cytotoxicity of iron oxide nanoparticles, with and without cobalt functionalization (Fe2O3 and Fe2O3@Co-PEG), using an established, ferroptosis-sensitive fibrosarcoma cell line (HT1080) and a normal fibroblast cell line (BJ). In addition, we evaluated poly (ethylene glycol) (PEG)-poly(lactic-co-glycolic acid) (PLGA)-coated iron oxide nanoparticles (Fe3O4-PEG-PLGA). Our results showed that all the nanoparticles tested were essentially non-cytotoxic at concentrations up to 100 μg/mL. However, when the cells were exposed to higher concentrations (200–400 μg/mL), cell death with features of ferroptosis was observed, and this was more pronounced for the Co-functionalized nanoparticles. Furthermore, evidence was provided that the cell death triggered by the nanoparticles was autophagy-dependent. Taken together, the exposure to high concentrations of polymer-coated iron oxide nanoparticles triggers ferroptosis in susceptible human cancer cells

CENTESIL: An independent Research Centre on Polysilicon

The tremendous expansion of the photovoltaic technology and its relative avidity for silicon is producing a dramatic change in the polysilicon industry structure, increasing the efforts to produce a low cost, high quality Solar Silicon. In this context, the Centro de Tecnología del Silicio Solar (CENTESIL) was founded in 2006 as a private-public partnership venture, and is currently building a 50 t/a pilot plant for silicon purification following the chlorosilane route. Although an advanced state of the art technology has been selected as first choice, the purpose is to be able to undertake developments in any topic that has the potential to reduce the cost effectively. Additionally, the project includes facilities for monocrystalline growth and wafering, and also the solar cell processing line of the Instituto de Energía Solar, so that it will cover the whole value chain from feedstock to solar cell

Influence des activités humaines sur la production et le stockage de matières à l'Holocène dans le bassin lacustre de Sarliève (Puy-de-Dôme, France)

L'objectif du programme est d'estimer l'impact des activités humaines sur le flux et le stockage de matières dans les bassins fluviatiles à l'Holocène, et en retour, d'évaluer l'impact des modifications anthropiques du milieu (sols et zones humides) sur ces activités. La méthode consiste à quantifier la matière (solide ou dissoute) prélevée aux versants à partir des stocks retenus dans les dépressions humides à différentes périodes de l'Holocène et en inférer des flux mis en relation avec le développement des sociétés

Magnetic Iron Oxide Colloids for Environmental Applications

This chapter deals with magnetic colloids with catalytic properties for the treatment of polluted waters and the efficient production of fuel alternatives. This kind of materials presents great advantages such as high surface/volume ratio, reproducibility, selectivity, ability to be magnetic harvested, functionalizable surfaces (e.g. with tunable pores and selective chelators deposited on them), high efficiencies and reusability. In particular, this chapter will consider the case of magnetic iron oxide colloids, which can be easily synthesized at low cost, are biocompatible and presents a well-developed surface chemistry. The most common techniques for the synthesis and functionalization of these magnetic nanoparticles will be reviewed and summarized. The iron oxide nanoparticles present outstanding properties that can be exploited in different aspect of the wastewater treatment such as heavy metals and organic pollutants removal by ionic exchange or adsorption, and degradation of the contaminants by advanced oxidation processes, among others. In the field of alternative energies, they have also been used as catalysts for biofuels production from oil crops, in Fischer-Tropsch reactions for liquid hydrocarbons and many other processes with potential environmental impact

Control of Italian ryegrass and Alexandergrass in corn using different corn sowing date, pre- and post-emergent herbicides.

Glyphosate-resistant (GR) Italian ryegrass (LOLMU) and Alexandergrass (URPLA) are troublesome weeds in corn cropping systems in Southern Brazil. The emergence pattern of those weeds is not uniform and may change according to the season?s environmental characteristics. Also, herbicide resistance has been diminishing the success of the weed control programs. The objectives of this study were to evaluate the influence of corn-sowing date on LOLMU and URPLA densities and their control provided by pre- and post-emergent herbicides. Field trials were conducted in two crop seasons in Southern Brazil consisting of three corn sowing date (August, September, and October) and the application of atrazine + S-metolachlor (residual) in corn pre-emergence in different post-emergence weed control programs with glyphosate, ammonium-glufosinate, nicosulfuron, and atrazine. The results indicated that the sowing date had a significant influence on LOLMU and URPLA densities. Corn sown in the earliest period was exposed to a higher LOLMU density, whereas corn sown in the latest period had a higher density of URPLA. Also, the application of residual herbicide at corn pre-emergence reduced both weed species densities and decreased the pressure for the control of glyphosate-resistant LOLMU for the post-emergence herbicides. The use of residual herbicides in corn pre-emergence is an efficient strategy to be considered in the LOLMU and URPLA control programs, followed by post-emergence application of glyphosate, ammonium-glufosinate, atrazine, and nicosulfuron