86,782 research outputs found
How to enhance the environmental sustainability of WEEE plastics management: An LCA study
No full textA new management scheme of plastics from waste of electrical and electronic equipment (WEEE), which includes novel treatments of sorting, dissolution/precipitation, extrusion, catalytic pyrolysis, and plastic upgrading, is proposed. Its environmental performances are quantified by an attributional Life Cycle Assessment and compared with those of European currently adopted schemes, which include conventional mechanical recycling and thermal treatments as well as improper options of dumping and open burning, largely applied to WEEE plastics exported to developing countries.
The proposed innovative scheme greatly enhances the environmental sustainability of WEEE plastics management, by increasing the annual amounts of polymers sent to recycling (from 390 kt/y up to 530 kt/y), decreasing residues to be sent to combustion (from 360 kt/y up to 60 kt/y), and reducing the potential impacts of all the midpoint categories under analysis (up to 580% for that of Global Warming). These results are mainly related to the adoption of a dissolution/precipitation process, which allows recovering target polymers such as ABS, HIPS and PC, with improvements in terms of Global Warming, Non-Carcinogens, and Carcinogens equal to 246%, 69% and 35%, even when the stages of polymer upgrading and catalytic pyrolysis are not included in the analysis. The sensitivity analysis shows that advantages of the new approach substantially disappear if the awful contributions of exportation outside Europe are taken into account. This clearly indicates that the first step to
enhance the sustainability of WEEE plastics management is a strong limitation of improper treatments applied to exported wastes.A new management scheme of plastics from waste of electrical and electronic equipment (WEEE), which includes novel treatments of sorting, dissolution/precipitation, extrusion, catalytic pyrolysis, and plastic upgrading, is proposed. Its environmental performances are quantified by an attributional Life Cycle Assessment and compared with those of European currently adopted schemes, which include conventional mechanical recycling and thermal treatments as well as improper options of dumping and open burning, largely applied to WEEE plastics exported to developing countries. The proposed innovative scheme greatly enhances the environmental sustainability of WEEE plastics management, by increasing the annual amounts of polymers sent to recycling (from 390 kt/y up to 530 kt/y), decreasing residues to be sent to combustion (from 360 kt/y up to 60 kt/y), and reducing the potential impacts of all the midpoint categories under analysis (up to 580% for that of Global Warming). These results are mainly related to the adoption of a dissolution/precipitation process, which allows recovering target polymers such as ABS, HIPS and PC, with improvements in terms of Global Warming, Non-Carcinogens, and Carcinogens equal to 246%, 69% and 35%, even when the stages of polymer upgrading and catalytic pyrolysis are not included in the analysis. The sensitivity analysis shows that advantages of the new approach substantially disappear if the awful contributions of exportation outside Europe are taken into account. This clearly indicates that the first step to enhance the sustainability of WEEE plastics management is a strong limitation of improper treatments applied to exported wastes
Chromosome Conformation Capture Followed by Genome-Wide Sequencing (Hi-C) in Drosophila Embryos
No full textThis protocol provides specific details on how to perform Hi-C, the genome-wide version of Chromosome Conformation Capture (3C) followed by high-throughput sequencing, in Drosophila embryos. Hi-C provides a genome-wide population-averaged snapshot of the 3D genome organization within nuclei. In Hi-C, formaldehyde-cross-linked chromatin is enzymatically digested using restriction enzymes; digested fragments are biotinylated and subjected to proximity ligation; ligated fragments are purified using streptavidin followed by paired-end sequencing. Hi-C allows the detection of higher order folding structures such as topologically associated domains (TADs) and active/inactive compartments (A/B compartments, respectively). Performing this assay in developing embryos gives the unique opportunity to investigate dynamic chromatin changes when 3D chromatin structure is established in embryogenesis
Biogas-to-biomethane upgrading: A comparative review and assessment in a life cycle perspective
No full textThe study reviews and compares the most utilised techniques to obtain high quality biomethane by upgrading biogas from anaerobic digestion of the organic fraction of municipal solid waste. Environmental and economic aspects of membrane separation, water scrubbing, chemical absorption with amine solvent, and pressure swing adsorption have been quantified in a life cycle perspective. An attributional environmental Life Cycle Assessment has been implemented with the support of a Material Flow Analysis and in combination with a complementary environmental Life Cycle Costing. The analyses are based on data largely obtained from Italian existing plants but they can be generalised to the whole European Union, as demonstrated by a companion sensitivity analysis. The comparative assessment of the results indicates all the examined options as fully sustainable, also identifying the “win-win” situations. In particular, the membrane separation technique appears to have the best performances, even though in some cases with limited differences. With reference to base case scenarios, this technique shows better results for the respiratory inorganics potential (up to 34%, i.e. up to 328 kgPM2.5eq/y), global warming potential (up to 7%, i.e. up to 344 tCO2eq/y), and non-renewable energy potential (up to 12%, i.e. up to 6400 GJprimary/y) as well as for life cycle costs (up to 3.4%, i.e. about 60 k€/y). The performances of the examined techniques appear anyway dependent on site-specific conditions (such as the injection pressure in the gas grid or the existence/amount of local economic incentives) and commercial strategies for the market of interest
Molecular dynamics characterization of the SAMHD1 Aicardi–Goutières Arg145Gln mutant: structural determinants for the impaired tetramerization
No full textAicardi-Goutières syndrome, a rare genetic disorder characterized by calcification of basal ganglia, results in psychomotor delays and epilepsy states from the early months of children life. This disease is caused by mutations in seven different genes encoding proteins implicated in the metabolism of nucleic acids, including SAMHD1. Twenty SAMHD1 gene variants have been discovered and in this work, a structural characterization of the SAMHD1 Aicardi-Goutières Arg145Gln mutant is reported by classical molecular dynamics simulation. Four simulations have been carried out and compared. Two concerning the wild-type SAMHD1 form in presence and absence of cofactors, in order to explain the role of cofactors in the SAMHD1 assembly/disassembly process and, two concerning the Arg145Gln mutant, also in presence and absence of cofactors, in order to have an accurate comparison with the corresponding native forms. Results show the importance of native residue Arg145 in maintaining the tetramer, interacting with GTP cofactor inside allosteric sites. Replacement of arginine in glutamine gives rise to a loosening of GTP-protein interactions, when cofactors are present in allosteric sites, whilst in absence of cofactors, the occurrence of intra and inter-chain interactions is observed in the mutant, not seen in the native enzyme, making energetically unfavourable the tetramerization process
DWT and QR code based watermarking for document DRM
No full textQuesto articolo presenta uno schema per la protezione dei diritti digitali per ogni tipo di documento presentato come immagine, usando passi che usano la crittografia e il watermarking. Le entità coinvolte in questo processo sono due: il proprietario del documento che ne possiede i diritti digitali e un utente generico che può scaricare o vedere una versione con watermark del documento originale. La versione con watermark contiene un codice QR che è inserito ripetutamente, e criptato, dal proprietario dei diritti sul documento, nelle componenti in frequenza dell'immagine, così producendo l'immagine con watermark. Il codice QR contiene un identificativo firmato che univocamente identifica ogni utente che usa il sistema. Lo schema, di tipo non-cieco, raggiunge una buona qualità percettiva e una discreta robustezza usando il terzo livello della Trasformata Discreta basata su Wavelet. I risultati sperimentali mostrano che tramite l'inserzione di diverse occorrenze di un codice QR criptato otteniamo un approccio che è piuttosto resistente alla compressione JPEG, alla rotazione, al ritaglio, e al rumore sale e pepe.This paper presents a digital rights protection scheme for every type of document presented as an image, by using steps that use cryptography and watermarking. The entities involved in this process are two: the owner of the document that owns its digital rights and a generic user who can download or view a watermarked version of the original document. The watermarked version contains a QR code that is repeatedly inserted, and scrambled, by the document rights owner, into the frequency components of the image, thus producing the watermarked image. The QR code contains a signed ID that uniquely identifies every users using the system. The schema, a non-blind type, achieves good perceptive quality and fair robustness using the third level of the Discrete Wavelet Transform. The experimental results show that by inserting several occurrences of a scrambled QR code we get an approach that is quite resistant to JPEG compression, rotation, cropping, and salt and pepper noise
Modeling the effects of tolerances and assembly errors on the optical performances of parabolic collectors in a concentrating solar power system
No full textThe major problem related to the implementation of Concentrating Solar Power (CSP) systems is related to their Levelized Cost of Electricity (LCOE), which is still higher than that associated to other energy production methods, thus limiting their competitiveness. It is widely recognized that large cost savings can still be achieved by improving the collector and solar field designs. In this context, one important issue is that, currently, very detailed analyses of CSP components’ production tolerances and assembly/mounting errors are performed in order to guarantee the desired optical performances of a CSP plant. Unfortunately, these analyses require very large computational efforts, so that full design optimizations, implying many model runs, become almost impractical. Hence, the main objective of this work is that of developing new, lean methodologies, still relying on proper experimental knowledge, for supporting the CSP system optimal design at affordable computational expenses. The methodological approach stems from an extension of a semi-analytic model of literature for the calculation of the intercept factor, i.e., an important optical efficiency parameter. The proposed modifications explicitly account for the effects of the production tolerances and assembly/mounting errors by including simple, parameterized FEM calculations and geometric considerations. After properly casting the problem into a probabilistic framework, we exploit the simplicity and computational speed of the proposed model in order to perform a Sobol-based global sensitivity analysis (GSA) of the CSP optical performances. From a purely engineering point of view, the results of this kind of analysis provide fundamental insights for supporting a decision-making process aimed at optimizing the CSP component production and the solar plant assembly/mounting at a full power production scale
Virtual Screening for the Development of Dual-Inhibitors Targeting Topoisomerase IB and Tyrosyl-DNA Phosphodiesterase 1
No full textHuman topoisomerase IB is an important target in cancer therapy and drugs selectively stabilizing the topoisomerase IB-DNA covalent complex are in clinical use for several cancer types. Tyrosyl-DNA phosphodiesterase 1 is involved in the DNA repair resolving the topoisomerase IB-DNA covalent complex that is extremely dangerous for the survival of the cells since it produces an irreversible DNA damage. Given the close biological relationship between these two enzymes, the development of synergistic inhibitors, called dual-inhibitors, is an important challenge in cancer therapy and computer-aided drug design may help in the identification of the best compounds. In this review, an overview of the compounds inhibiting one of the two enzymes or acting as dual inhibitors is provided. Moreover, the general procedures of the virtual screening approach, providing a description of two widely used open-source programs, namely AutoDock4 and AutoDock Vina, are described. Finally, an application of the two programs on a selected number of dual inhibitors for tyrosyl-DNA phosphodiesterase 1 and topoisomerase IB and their performance is briefly discussed
A molecular dynamics simulation study decodes the early stage of the disassembly process abolishing the human SAMHD1 function
No full textThe human sterile alpha motif SAM and HD domain-containing protein 1 (SAMHD1) restricts in non-cycling cells type the infection of a large range of retroviruses including HIV-1, reducing the intracellular pool concentration of deoxynucleoside triphosphates (dNTPs) required for the reverse transcription of the viral genome. The enzyme is in equilibrium between different forms depending on bound cofactors and substrate. In this work, two SAMHD1 three-dimensional models have been investigated through classical molecular dynamics simulation, to define the role of cofactors and metal ions in the association of the tetrameric active form. A detailed analysis of the inter-subunit interactions, taking place at the level of helix 13, indicates that removal of metal ions and cofactors induces an asymmetric loosening of the monomer–monomer interface leading to the formation of a loose tetramer where the two dimeric interfaces are weakened in different way
Diagnosis of Langerhans cell histiocytosis on cytological examination of cerebrospinal fluid: Report of the first case
No full textLangerhans cell histiocytosis (LCH) is a disease of unknown etiology characterized by a proliferation of histiocytic cells resembling dendritic Langerhans cells. LCH can be unifocal or multifocal, with one‐ or many‐organ involvement. The serous fluids are rarely involved. Cytological diagnosis of LCH is possible and relies on recognition of the typical cytomorphological features and subsequent immunocytochemical confirmation. Given the possibility of multisystem involvement, after diagnosing LCH it is necessary to carry out staging exams such as a bone survey, abdominal ultrasound, complete blood count, screening for diabetes insipidus and pulmonary function tests. We present the first case of LCH where the diagnosis was reached on cytological material from the cerebrospinal fluid. To the best of our knowledge, this is the first such case reported in the international literature to date. The morphological and immunocytochemical characteristics of our case are described, and the relevant literature is reviewe
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