Magnetic nanostructures functionalized with a derived lysine coating applied to simultaneously remove heavy metal pollutants from environmental systems

ABSTRACT

The pollution of environmental systems with heavy metals is becoming a serious problem worldwide. These contaminants are one of the main issues in sludge (which is considered waste) and can even have harmful effects if the sludge is not treated properly. Thus, the development of a novel functional magnetic nanoadsorbent based on a derived lysine is reported here, which can be efficiently applied for metal removal from sludge. Magnetic nanoparticles were coated with silica layer and further modified by covalent bonding of derived lysine. The morphology of the nanomaterial, its nano-size and the silica layer thickness were analyzed by transmission electron microscopy. The successful silanization of the lysine derivative to the silica-coated magnetic nanostructures was investigated by several physicochemical characterization techniques, while the magnetic properties were measured with a vibrating sample magnetometer. The synthesized nanostructures were used as adsorbents for simultaneous removal of most critical heavy metals (Cr, Zn, Cu) from real complex sludge suspensions. The main practical adsorption parameters, pH of the native stabilized sludge, adsorbent amount, time, and adsorbent regeneration were investigated. The results show promising adsorption properties among currently available adsorbents (the total equilibrium adsorption capacity was 24.5 mg/g) from the sludge with satisfactory nanoadsorbent reusability and its rapid removal. The stability of the nanoadsorbent in the sludge, an important but often neglected practical parameter for efficient removal, was verified. This work opens up new possibilities for the development of high-quality magnetic nanoadsorbents for metal pollutants applied in various complicated environmental fields and enables waste recovery.     

The “Hitchhiker’s Guide to the Galaxy” of Endothelial Dysfunction Markers in Human Fertility

Endothelial dysfunction is an early event in the pathogenesis of atherosclerosis and represents the first step in the pathogenesis of cardiovascular diseases. The evaluation of endothelial health is fundamental in clinical practice and several direct and indirect markers have been suggested so far to identify any alterations in endothelial homeostasis. Alongside the known endothelial role on vascular health, several pieces of evidence have demonstrated that proper endothelial functioning plays a key role in human fertility and reproduction. Therefore, this state-of-the-art review updates the endothelial health markers discriminating between those available for clinical practice or for research purposes and their application in human fertility. Moreover, new molecules potentially helpful to clarify the link between endothelial and reproductive health are evaluated herein.     

“Drop your boat!”: The discursive co-construction of project renewal. The case of the Darwin mountaineering expedition in Patagonia

When a project faces an unexpected, ambiguous and risky environment, “drop your tools” often comes up against the reluctance of the actors to accept and implement its renewal. Our contribution aims to explore how team members discursively co-construct the sense of their situation and accept to “drop their tools”. Drawing upon a real-time, in situ ethnographic study of a mountaineering expedition in Patagonia, we conducted a discursive analysis of a project renewal episode. Our paper first contributes to shed light on an unexplored phenomenon: the construction and acceptance of “dropping the tools”. Second, we add to the literature on project renewal. Third, we show how team members make sense in real-time of their environment by drawing on four discursive practices (re-wording, reframing, focusing attention, and reaffirming team cohesiveness) in order to construct and accept project renewal.     

Monte carlo simulation of micro-cracking in polysilicon MEMS exposed to shocks

In this work we exploit a multi-scale framework to model the shock-induced failure of polysilicon micro electro-mechanical systems (MEMS), and study the impact of uncertainties at polycrystal length-scale on the results. Because of polysilicon brittleness, MEMS sensors almost instantaneously fail by micro-cracking when subjected to shocks. Since the length of the zone where such micro-cracking is spreading can amount to 5–10% of the characteristic grain size, the morphology of polysilicon films constituting the movable parts of the MEMS is explicitly modeled at the micro-scale within a cohesive approach. Focusing on shocks induced by accidental drops, forecasts of MEMS failure are obtained through a Monte Carlo methodology, wherein statistics of the polycrystalline morphology are accounted for. Outcomes, in terms of failure mode and drop height leading to failure, are shown to correctly represent available experimental evidences relevant to a commercial micro-device.     

The Po River Delta (North Italy) Indoor Epidemiological Study: Home Characteristics,Indoor Pollutants,and Subjects' Daily Activity Pattern

Abstract A total of 140 homes in the Po River Delta area of North Italy (near Venice) were monitored during summer and winter to measure the concentration of nitrogen dioxide (NO₂), and respirable suspended particulate matter (RSP, ≤ 2.5 μm). In this paper, the findings on home characteristics, daily activity pattern of occupants, and residential indoor air quality are described. Our study confirms that people spend the greater part of their daily lives indoors (84%), especially at home (64%). The concentration of monitored pollutants was greater in winter than in summer. The highest levels of NO₂ were found in the kitchens. Significantly higher indoor NO₂ levels were found in the houses with gas-furnace heating and/or with gas water heater located inside the home. RSP was significantly higher in homes where tobacco smoking took place, and was significantly related to the number of cigarettes smoked. A significant relationship between NO₂ indoor concentrations and RSP values in both seasons was found.     

Effect of Nitrification and GAC Filtration on Copper and Lead Leaching in Home Plumbing Systems

Nitrification and granular activated carbon (GAC) filtration impact leaching of lead/copper to potable water under typical home plumbing configurations. GAC filters removed the disinfectant and caused rapid establishment of nitrification in chloraminated systems. The potential adverse consequences of whole house GAC filters deserve increased scrutiny in chloraminated systems. The lower pH values from nitrification and other microbes during overnight stagnation in pipes can markedly increase (up to 800%) lead and copper contamination of water.     

A CMOS sensor optimized for laser spot-position detection

An optical sensor architecture optimized for flying-spot, triangulation-based, three-dimensional (3-D) laser scanners will be presented. The architecture implements a spot-position detection algorithm based on a two-step procedure that allows for improved dynamic range and readout speed. The sensor, which contains two linear arrays of pixels, analog readout channels, and digital signal preprocessing circuitry, has been fabricated in 0.6-/spl mu/m CMOS double-poly triple-metal technology and measures 8.17/spl times/5.67 mm/sup 2/. Pixel size and shape have been selected for reducing the effect of laser speckle and for the possibility of measuring color in a multiwavelength 3-D scanner. Electrooptical test results confirm the sensor behavior as expected from simulations on a dynamic range of 80 dB and exhibits a maximum speed of 50-k voxel/s.     

Experimental analysis of the aerodynamic performance of an innovative low pressure turbine rotor

In the present work the aerodynamic performances of an innovative rotor blade row have been experimentally investigated. Measurements have been carried out in a large scale low speed single stage cold flow facility at a Reynolds number typical of aeroengine cruise, under nominal and off-design conditions. The time-mean blade aerodynamic loadings have been measured at three radial positions along the blade height through a pressure transducer installed inside the hollow shaft, by delivering the signal to the stationary frame with a slip ring. The time mean aerodynamic flow fields upstream and downstream of the rotor have been measured by means of a five-hole probe to investigate the losses associated with the rotor. The investigations in the single stage research turbine allow the reproduction of both wake-boundary layer interaction as well as vortex-vortex interaction. The detail of the present results clearly highlights the strong dissipative effects induced by the blade tip vortex and by the momentum defect as well as the turbulence production, which is generated during the migration of the stator wake in the rotor passage. Phase-locked hot-wire investigations have been also performed to analyze the time-varying flow during the wake passing period. In particular the interaction between stator and rotor structures has been investigated also under off-design conditions to further explain the mechanisms contributing to the loss generation for the different conditions.     

Polymorphism of human pituitary FSH: analysis of immunoreactivity and in vitro bioactivity of different molecular species

Follicle-stimulating hormone is known to be highly heterogeneous in serum and in the pituitary. In the present study, we have partially separated different molecular species of human pituitary FSH and characterized their immunoreactivity and in vitro bioactivity. Pooled extracts of male (n = 15) and female (n = 9) human pituitary glands were chromatographed on a column of Sephacryl S-200 and FSH-containing fractions were fractionated by chromatofocusing in the pH range 4-6. FSH was measured in the individual fractions by an in vitro bioassay, based on the FSH-dependent aromatase activity of immature rat Sertoli cells, and by the following methods based on commercial kits: radioimmunoassay (RIA), immunofluorimetric assay (IFMA), immunoradiometric assay (IRMA), immunoenzymometric assay (IEMA). In each assay, the kit standard, calibrated against the 2nd International Reference Preparation (IRP) 78/549, and the International Standard (IS) 83/575 were run in parallel. The relative potencies of the kit standards in terms of IS 83/575 were: IFMA 3.08, IRMA 1.62, RIA 2.42, IEMA 1.45 and bioassay 1.14. After chromatofocusing, pituitary FSH eluted mostly in fractions with pH approximately 4.5, without sex-related differences. In both sexes approximately 25% of bioactive material showed a pI < 4 and eluted with 1 M NaCl. Although the same IS 83/575 was used in the various assays, the profiles of immunoreactive FSH were significantly different. The highest intermethod variability was observed in the case of male pituitary FSH. The relative biopotency of the different molecular species of FSH did not appear to change according to their pI but, rather, varied with the assay method and the standard.(ABSTRACT TRUNCATED AT 250 WORDS)