1,564 research outputs found

    Soil contamination evaluation by Enrichment Factor (EF) and Geoaccumulation Index (Igeo)

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    Heavy metals are natural constituents of soils and their concentration varies depending on parental materials. The soils were formed by. In the last years, the content of heavy metal in soils has increased due to human activities as: distribution of fertilizers, pesticides, industries, waste disposal and air pollution. Due to these activities the life capacity of soils decreased; especially where the natural background is already high because of natural parental material richness in heavy metal. As a matter of fact it is very important to distinguish between the natural background values and anthropogenic inputs, and to understand that the background values change from area to area and with the scale of the area investigated. To evaluate the soil contamination rate different indexes like Enrichment Factor (EF) and geoaccumulation index (Igeo) can be applied. These indexes are used to assess the presence and intensity of anthropogenic contaminant deposition on surface soil

    Strontium Isotope as Tracers of Groundwater Contamination

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    Groundwater flowing under a municipal solid waste landfill has been studied to identify potential contamination phenomenon and to test strontium isotopic composition as a natural tracer of contamination. The study was carried on in June 2014 in central Italy. Five selected boreholes were selected and analysed according to their location related to the site. Samples taken from boreholes placed upward to the site were considered as uncontaminated groundwater. One borehole located downward from the site and with major contaminant values has been considered as potentially contaminated end-member. Sr isotope results show that samples located upward from the site present lower Sr concentration and highest Sr isotopic values, which reflects weathered bedrock, while borehole located downward from the site show lowest Sr values and 87Sr/86Sr ratio, probably due to pollution by landfill leachate. The mixing calculation highlights the possible mixing phenomenon for the other samples located downward from the site

    Advanced Membrane Operations in CO2 Capture

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    Membrane-based gas separation systems are today widely accepted and, in many cases, used as a unit operation for generation, separation and purification of gases in gas, chemical, petroleum and allied industries. There are several applications of membrane gas separation and several membrane materials and membrane modules solutions available today for the various fields of interest. CO2 separation from flue gas coming out from a power plant or a cement industry, as well as CO2 from biogas and natural gas is one of these fields. Polymeric membranes, thermally rearranged polymer membranes, mixed matrix membranes, etc. are some examples of membranes investigated c/o the ITM-CNR for separating gases, such as, CO2, CH4, etc. of interest for many industrial cycles. The mass transport properties of these membranes were analyzed feeding gas streams, with different content of water vapor and other aggressive components; these being one of the crucial assets for moving towards to real applications [1,2]. Other aspects, such as aging owing to water vapor, physical compaction, thermal cycles and contaminants were and are currently under investigation, also with long term characterizations [3]. To this purpose, together with material science, membrane engineering covers a fundamental role in the development of this technology and its scale-up. Modelling assists experimental analysis for a unified approach in advanced membrane unit operations. In this logic, a tool was developed in terms of performance maps suitable for analyzing also membrane-integrated systems identifying proper operating conditions and proposing possible process schemes for achieving the desired targets for the various streams of interest [4,5]. Among the main results achieved, there are the mass transport characterization of membranes, membrane properties restoring after long-time operation, modelling of the membrane gas separation as unit operation and its inclusion in more complex production cycles. 1. Cersosimo, A. Brunetti, E. Drioli, G. Dong, K. T. Woo, J. Lee, Y. M. Lee, G. Barbieri, “Separation of CO2 from humidified ternary gas mixtures using thermally rearranged polymeric membranes”, J. Membr. Sci., 2015 (492), 257-262. DOI: 10.1016/j.memsci.2015.05.072 2. Brunetti A.; Cersosimo M.; Kim J.S.; Dong G.; Fontananova E.; Lee Y.M.; Drioli E.; Barbieri G. “Thermally rearranged mixed matrix membranes incorporating oxidized carbon nanotubes for CO2 separation”, International Journal of Greenhouse Gas Control 2017, submitted 3. Brunetti A.; Cersosimo M.; Dong G.; Woo K.T.; Lee J.; Kim J.S.; Lee Y.M.; Drioli E.; Barbieri G. “In situ restoring of aged thermally rearranged gas separation membranes”, J. Membr. Sci., 2016, 520, 671-678, DOI: 10.1016/j.memsci.2016.07.030 4. Brunetti A.; Drioli E.; Lee Y.M.; Barbieri G.; “Engineering evaluation of CO2 separation by membrane gas separation systems”, J. Membr. Sci., 2014, 454, 305-315; DOI: 10.1016/j.memsci.2013.12.037 5. Brunetti A.; Scura F.; Barbieri G.; Drioli E.; Membrane technologies for CO2 separation”, J. Membr. Sci., 2010, 359, 115-125; DOI: 10.1016/j.memsci.2009.11.040 ACKNOWLEDGEMENTS The “Ministero degli Affari Esteri, Direzione Generale per la Promozione e la Cooperazione Culturale” of Italy is gratefully acknowledged for the financial support of project “New highly innovative membrane operations for CO2 separation (capture) at medium and high temperature: Experimental preparation and characterization, theoretical study on elementary transport mechanisms and separation design” co-funded in the framework of a bilateral agreement between MAECI (Italy) and MOST (South Korea). The “Ministero per l’Istruzione, l’Università e la Ricerca” of Italy, Ricerca e competitività 2007-2013, is gratefully acknowledged for the financial support of the project PON 01_02257 “FotoRiduCO2 - Photoconversion of CO2 to methanol fuel”, (“Studio e sperimentazione di sistemi di foto conversione con luce solare di CO2 in metanolo, da utilizzare come combustibile”)

    Experimental Realization of Polarization Qutrits from Non-Maximally Entangled States

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    Based on a recent proposal [Phys. Rev. A 71, 062337 (2005)], we have experimentally realized two photon polarization qutrits by using non-maximally entangled states and linear optical transformations. By this technique high fidelity mutually unbiased qutrits are generated at a high brilliance level.Comment: RevTex, 8 pages, 6 figure

    Two-loop heavy top effects on the MZ-MW interdependence

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    The O(alpha^2 mt^2/mw^2) correction to the relation between G_\mu and the vector boson masses is computed in the MSbar scheme, and the results are used to investigate the magnitude of the effect on the theoretical prediction of mw and sin^2\theta_\msbar(mz) from alpha, G_\mu, and mz.Comment: 11 pages, LaTeX, includes 1 LaTeX figure, uses equations.sty and cite.sty, one minor comment and interpolation function for variable mtop added, no change in the result

    Adaptive real time selection for quantum key distribution in lossy and turbulent free-space channels

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    The unconditional security in the creation of cryptographic keys obtained by quantum key distribution (QKD) protocols will induce a quantum leap in free-space communication privacy in the same way that we are beginning to realize secure optical fiber connections. However, free-space channels, in particular those with long links and the presence of atmospheric turbulence, are affected by losses, fluctuating transmissivity, and background light that impair the conditions for secure QKD. Here we introduce a method to contrast the atmospheric turbulence in QKD experiments. Our adaptive real time selection (ARTS) technique at the receiver is based on the selection of the intervals with higher channel transmissivity. We demonstrate, using data from the Canary Island 143-km free-space link, that conditions with unacceptable average quantum bit error rate which would prevent the generation of a secure key can be used once parsed according to the instantaneous scintillation using the ARTS technique

    Experimental Techniques to Investigate Residual Stress in Joints

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    Residual stress arising from welding processes is matter of great concern in industrial practice since it can affect geometry, mechanical behavior and corrosion resistance of components. In order to evaluate residual stress in welded joints and optimize post-welding heat treatments, a lot of work has been devoted to the improvement of measurement methods with increasing sensitivity and accuracy. The chapter presents and discusses some of the experimental techniques commonly used today to determine residual stress in welds and describes recent results and advancements. Destructive (sectioning, contour, hole-drilling, instrumented indentation) and nondestructive (Barkhausen noise, ultrasonic, X-ray and neutron diffraction) methods are illustrated to highlight the specific characteristics, advantages and drawbacks

    Application of 2H and 18O Isotopes for Tracing Municipal Solid Waste Landfill Contamination of Groundwater. Two Italian Case Histories

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    Groundwater contamination due to municipal solid waste landfills leachate is a serious environmental threat. During recent years, the use of stable isotopes as environmental tracers to identify groundwater contamination phenomena has found application to environmental engineering. Deuterium (2H) and oxygen (18O) isotopes have successfully used to identify groundwater contamination phenomena if submitted to interactions with municipal solid waste landfills leachate, with a significant organic amount. The paper shows two case studies, in central and southern Italy, where potential contamination phenomenon of groundwater under municipal solid waste landfills occurred. In both cases, isotope compositions referred to 2H and 18O highlight a δ2H enrichment for some groundwater samples taken in wells, located near leachate storage wells. The δ2H enrichment is probably caused by methanogenesis phenomena, during which the bacteria use preferentially the hydrogen “lighter” isotope (1H), and the remaining enriched the “heavier” isotope (2H). The study of the isotope composition variation, combined with the spatial trend of some analytes (Fe, Mn, Ni) concentrations, allowed to identify interaction phenomena between the municipal solid waste landfills leachate and groundwater in both case histories. Therefore, these results confirm the effectiveness of 2H isotopes application as environmental tracer of groundwater contamination phenomena due to mixing with municipal solid waste landfills leachate
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