1,589 research outputs found

    Consolidation of Stone Materials by Organic and Hybrid Polymers: An Overview

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    Historic stone buildings and monuments undergo a gradual, unstoppable, and episodic deterioration due to environmental or climatic impact, biological or mechanical deterioration, or, in the case of better-preserved structures, inadequate maintenance. Water infiltration, freezing and thawing, carbonation, wind erosion, acid rain, and graffiti/vandalism are the key “environmental” issues that strongly impact cultural heritage and therefore must be limited or even prevented. This interaction leads to the occurrence of different phenomena, possibly involving blistering phenomena on the stone surface, its gradual weather away, leaving a sound surface behind, or the dropping away of the bulk material, because of prolonged weathering, in a single event. It is noteworthy that, quite often, the stone may appear perfectly intact to the naked eye, though it is losing its cohesion beneath its surface. Therefore, it becomes necessary to either efficiently protect the stone substrates to prolong their life, or to fix the damage that already occurred by means of effective, reliable, and long-lasting consolidation/restoration strategies. This work aims at summarizing the current state-of-the-art referring to the use of monomeric/oligomeric or polymeric consolidants, providing the reader with some perspectives for the next future

    Insights into Induction Heating Processes for Polymeric Materials: An Overview of the Mechanisms and Current Applications

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    In polymer systems, induction heating (IH) is the physical outcome that results from the exposure of selected polymer composites embedding electrically-conductive and/or ferromagnetic fillers to an alternating electromagnetic field (frequency range: from kHz to MHz). The interaction of the applied electromagnetic field with the material accounts for the creation of magnetic polarization effects (i.e., magnetic hysteresis losses) and/or eddy currents (i.e., Joule losses, upon the formation of closed electrical loops), which, in turn, cause the heating up of the material itself. The heat involved can be exploited for different uses, ranging from the curing of thermosetting systems, the welding of thermoplastics, and the processing of temperature-sensitive materials (through selective IH) up to the activation of special effects in polymer systems (such as self-healing and shape memory effects). This review aims at summarizing the current state-of-the-art of IH processes for polymers, providing readers with the current limitations and challenges, and further discussing some possible developments for the following years

    Dioxins and PCBs in solid matter from the river Elbe, its tributaries and the North Sea (longitudinal profile, 2008)

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    The most recent longitudinal sampling profile, taken in 2008 from the river Elbe and its tributaries Vltava (Moldau), Mulde, Spittelwasser, Saale, Bode the Stör and the North Sea near Helgoland, shows contaminations of solid matter with polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (dioxins, PCDD/Fs) and polychlorinated biphenyls (PCBs). While the dioxin contamination is mainly located along the German part of the catchment, PCBs are more abundant in the Czech section. In some of the 43 solid samples investigated high levels of contamination were detected. Selected orientation benchmarks for dioxins and PCBs in sediments and fish are exceeded, suggesting potential hazards for organisms in the contaminated rivers and for human consumption. Elevated dioxin concentrations in the Spittelwasser-Mulde system and the Saale catchment, together with consistent dioxin congener patterns Elbe downstream of the confluence, indicate that the region of Bitterfeld-Wolfen is the predominant source of the dioxin pollution, which can be traced until far off shore in the sediments of the North Sea near Helgoland. Thermal metal, presumably Magnesium production via fused salt electrolysis during the 2nd world war is the most probable primary, historic source of the dioxin contamination. The spatial distribution of dioxins as seen in 2008 matched well with earlier campaigns in 2002, both for aquatic solids and alluvial soils, suggesting minor change of the situation since then. Also the samples from the North Sea revealed elevated levels of dioxins that display the congener pattern from the Bitterfeld-Wolfen Region. In contrast to the PCDD/Fs, PCBs are mainly present in the in the Upper Elbe in the Czech Republic. After the German border PCBs display an overall decrease. Other than PCDD/Fs, PCB emissions into the Elbe cannot be attributed to a dominant source or region. Indicator PCBs did rise more or less constantly in concentration until the German border, suggesting a variety of cumulative emission sources along the whole Czech stretch. Thus, no specific recommendation on how to decrease the PCB pressure on the River Elbe can be given on the basis of the data acquired in this study. Detailed regional scale monitoring in the Czech stretch, together with the evaluation of production statistics regarding potential PCB sources are needed here. After all the PCB toxicity in eel is exceeding that of PCDD/F up to an order of magnitude (investigations of eels taken after the flood event in August 2002). As an amendment to the chemical analyses, two Ah-receptor based bioassays (DR CALUXR and EROD), which display the dioxin–like activity of all pollutants present, were performed on a subset of the samples (blind study). For The DR CALUXR the comparison revealed a good agreement between the HRGC/HRMS results along the German stretch and the bioassay. However, along the Czech section of the Elbe the DR CALUXR displayed a 10 times higher dioxin-like activity than the chemical analyses. This suggests that the solid material in the Czech section contains additional persistent dioxin-like acting pollutants. In comparison to the DR CALUXR test, the EROD assay displayed even higher dioxin-like activities. The differences can be explained by the fact that the clean up procedure for the DR CALUXR eliminated the less persistent organic pollutants in the extract, while the EROD procedure remained sensitive to those. Regarding the risk for the aquatic food chain and the human diet, the reduction of PCBs in the River Elbe ecosystem appears crucial as indicated by the dominance of the PCB over the PCDD/Fs in toxicity equivalents detected in eel samples.JRC.H.1-Water Resource

    Development and reproduction of Cataclysta lemnata, a potential natural enemy of the invasive alien duckweed Lemna minuta in Italy

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    Life cycle of the aquatic moth Cataclysta lemnata (Lepidoptera: Crambidae) was studied in laboratory conditions to obtain a basic biological knowledge useful for predicting the possible success of the herbivorous larvae of this insect as potential control agents in limiting the spread of the invasive American duckweed Lemna minuta (Alismatales: Araceae) in Italy. The multivoltinism of C. lemnata, as well as the high overall emergence from the pupal stage (85%), the high success in mating among the formed couples (>90%), and the high number of larvae born from each egg laying (on average 310 individuals), suggest that the insect can be successfully bred in the laboratory for the purposes of an augmentative biological control. Under experimental conditions, larvae developed in 23 days (through six larval instars, distinguishable by cephalic capsule dimensions) and pupae in 10, with no difference in duration between females and males. The larval phase resulted longer than the adult one (23 vs 10 days), therefore it can be considered the most suitable stage for releasing the insect in field for biocontrol purposes. Indeed, the larvae having a herbivorous diet might consume large amount of the invasive plant, contrarily to the adult phase which is focused exclusively on reproduction. The results emerged not only allow to contribute to the knowledge on aquatic lepidoptera that are scarcely known, but also support the effectiveness of a possible protocol for an augmentative biological control of the invasive alien duckweed L. minuta

    Analysis of chemical constitutents and additives in hydraulic fracturing waters 1. Technical review and proposal for a non-target approach

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    This technical report is a first one of series of reports addressing the issue of chemical constituents and additives occurring in the waters related to hydraulic fracturing in the exploitation of unconventional hydrocarbons. Specific focus is on the types of chemical constituents being addressed so far in flowaback, produced waters and potentially exposed ground and surface water. It gives on overview on typical approaches. With regard to organic constituents it addresses the typically examined compounds and investigates to which extent non-targeted approaches with accurate mass spectrometry can be used to fill existing knowledge gaps. The concept of an envisaged feasibility study for a imoproved baseline assessment is described, too.JRC.D.2-Water and Marine Resource

    HCHs in solid matter from the River Elbe, its tributaries and the North Sea

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    The River Elbe (Czech: Labe ) is one of the major rivers of Central Europe. It originates in the Krkonoše Mountains of northwestern Czech Republic before traversing Bohemia (Czech Republic), then Germany and flowing into the North Sea at Cuxhaven, 110 km northwest of Hamburg. Its total length is 1,094 km. The Elbe’s major tributaries are the Vltava (German: Moldau), Saale, Havel, Mulde, SchwarzeElster, and Ohre rivers. The Elbe River basin, comprising the Elbe and its tributaries, has a catchment area of 148,268 km2, the fourth largest in Europe. The basin spans four countries, with its largest parts in Germany (65.5%) and the Czech Republic (33.7%). Much smaller parts lie in Austria (0.6%) and Poland (0.2%). The basin is inhabited by 24.5 million people (1). Organochlorine pesticides are man-made organics chemicals. Hexachlorocyclohexanes (HCHs) have been extensively used and are therefore found widely distributed in the environment. HCHs are listed under the Stockholm Convention on POPs (persistent organic compound) and are included into the priority list of Water Frame Directive. Here we show the results of HCHs in solids matter of 35 different sites along the River Elbe, selected tributaries, and the North SeaJRC.H.1-Water Resource

    Synthetic Control Group Methods in the Presence of Interference: The Direct and Spillover Effects of Light Rail on Neighborhood Retail Activity

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    In recent years, Synthetic Control Group (SCG) methods have received great attention from scholars and have been subject to extensions and comparisons with alternative approaches for program evaluation. However, the existing methodological literature mainly relies on the assumption of non-interference. We investigate the use of the SCG method in panel comparative case studies where interference between the treated and the untreated units is plausible. We frame our discussion in the potential outcomes approach. Under a partial interference assumption, we formally define relevant direct and spillover effects. We also consider the "unrealized" spillover effect on the treated unit in the hypothetical scenario that another unit in the treated unit's neighborhood had been assigned to the intervention. Then we investigate the assumptions under which we can identify and estimate the causal effects of interest, and show how they can be estimated using the SCG method. We apply our approach to the analysis of an observational study, where the focus is on assessing direct and spillover causal effects of a new light rail line recently built in Florence (Italy) on the retail density of the street where it was built and of the streets in the treated street's neighborhood

    Polychlorinated Biphenyls (PCBs) at the JRC Ispra Site: Air Concentrations, Congener Patterns and Seasonal Variation-Results from the 1st Year of Atmospheric Monitoring of Persistent Organic Pollutants (POPs) at the Ispra EMEP Station

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    With the aim of gathering information on atmospheric POPs concentrations in one of the ¿monitoring holes¿ in Europe, a monitoring and research atmospheric site was set up at the JRC Ispra Site. Regular monitoring activities started on April 2005 and finished on March 2007 in this first stage. Air and precipitation samples were collected regularly throughout this period. First results obtained on PCBs ambient air concentrations (7 indicator PCBs: 28, 52, 101, 118, 153, 138 and 180) from the first year of monitoring (April 2005-2006) are presented in this report. In addition, congener patterns, air gas/particulate phase partition and seasonal variation are discussed. The range of ¿7 PCB total (gas + particulate phases) monthly averaged concentration during the sampling period varied from 76 ± 17 to 31 ± 5 pg m-3. Concentrations are within the range of those reported for rural, semi-rural or remote areas around the world. A seasonal variation of air concentrations was observed, with higher levels in summer months (higher average temperatures) and lower values in winter (lower average temperatures). In addition, indications of seasonal variation affecting congener patterns and the gas - particulate phase partition for the studied PCB were found. PCBs were in general predominant in the air gas phase, dominating therefore the contribution to the total airborne concentration, although the percentage in the gas phase decreases when increasing level of chlorination and during the low temperature season (winter months). A one year data set of PCB ambient air concentrations has been generated, constituting a useful dataset that now remains available for further use, such as inclusion in the EMEP network or for POPs fate modelling validation and future risk assessment of POPs in sub-alpine locations. More results for other target POPs are under processing and are expected to be reported soon.JRC.H.5-Rural, water and ecosystem resource

    Validation of analytical methods for the WFD “watch list” pilot exercise

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    Validation of an analytical method is a necessary step in controlling the quality of quantitative analysis. Method validation is an established process which is the provision of documentary evidence that a system fulfills its pre-defined specification or the process of providing that an analytical method is acceptable for its intended purpose. The objectives of the present study were: • to validate a SPE-LC-MS/MS method for the determination of carbamazepine (CBZ), 10,11-dihydro-10,11-dihydroxy-carbamazepine (CBZ-DiOH), sulfamethoxazole (SMZ) and pentafluoropropionic acid (PFPrA) in surface water samples; • to validate a SPE-GC-MS method for the determination of tris (1-chloro-2-propyl) phosphate (TCPP) content in surface water samples. Method validations were performed according to the ISO 17025 requirement and the BT/TF151 WI CSS 99026 document. The calibration curves, working ranges, recoveries, detection and quantification limits, trueness as well as repeatability were determined. The budget uncertainty was also estimated following a top-down approach based on in-house validation data.JRC.H.1-Water Resource

    Vapor‐Phase Synthesis of Molecularly Imprinted Polymers on Nanostructured Materials at Room‐Temperature

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    Molecularly imprinted polymers (MIPs) have recently emerged as robust and versatile artificial receptors. MIP synthesis is carried out in liquid phase and optimized on planar surfaces. Application of MIPs to nanostructured materials is challenging due to diffusion-limited transport of monomers within the nanomaterial recesses, especially when the aspect ratio is >10. Here, the room temperature vapor-phase synthesis of MIPs in nanostructured materials is reported. The vapor phase synthesis leverages a >1000-fold increase in the diffusion coefficient of monomers in vapor phase, compared to liquid phase, to relax diffusion-limited transport and enable the controlled synthesis of MIPs also in nanostructures with high aspect ratio. As proof-of-concept application, pyrrole is used as the functional monomer thanks to its large exploitation in MIP preparation; nanostructured porous silicon oxide (PSiO2) is chosen to assess the vapor-phase deposition of PPy-based MIP in nanostructures with aspect ratio >100; human hemoglobin (HHb) is selected as the target molecule for the preparation of a MIP-based PSiO2 optical sensor. High sensitivity and selectivity, low detection limit, high stability and reusability are achieved in label-free optical detection of HHb, also in human plasma and artificial serum. The proposed vapor-phase synthesis of MIPs is immediately transferable to other nanomaterials, transducers, and proteins
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