340 research outputs found

    Μελέτη οχήματος πόλης με τεχνολογία φιλική προς το περιβάλλον

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    114 σ.Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) "Συστήματα Αυτοματισμού"Η επικράτηση του κινητήρα εσωτερικής καύσης στα οχήματα τον 20ο αιώνα προκάλεσε βλαπτικές παρενέργειες σημαντικής έκτασης και έντασης. έτσι κινητοποιήθηκε το παγκόσμιο επιστημονικό δυναμικό, προκειμένου να εξευρεθούν τρόποι αντιμετώπισης του προβλήματος. Οι αριθμοί των οχημάτων που προστίθενται κάθε χρόνο στην κυκλοφορία επιτείνουν τα φαινόμενα και καθιστούν επιτακτική την ανάγκη λήψης άμεσων μέτρων. Η αντικατάσταση του κιντήρα εσωτερικής καύσης διαφαίνεται ότι είναι θεμα χρόνου. Σκοπός της εργασίας αυτής είναι η ανασκόπιση των τεχνολογικών επιτευγμάτων που θα συμβάλλουν στο σχεδιασμό ενός οχήματος μηδενικής ρύπανσης. Ηχρήση νέων έξυπνων υλικών, η μείωση του βάρους, οι ανανεώσιμες πηγές ενέργειας, η ανλακτηση ενέργειας μέσω φρεναρίσματος είναι μερικές από τις εφαρμογές που αναπτύσσονται. Μακροπρόθεσμα αναμένεται να συμβάλλουν τεχνολογίες όπως οι κυψέλες καυσίμου και τα βιοκαύσιμα, ενώ στο άμεσο μέλλον αναμένεται να κυκλοφορήσουν πολλά ηλεκτρικά υβριδικά οχήματα στην αγορά.The prevalence of internal engine combustion engine vehicles of road transport during the 20th century caused extended damaging side affects. Therefore, the world's scientific potential is working in order for this problem to be confronted. The increase of the vehicles worsens this situation and it is necessary to act immediately against it. The replacement of the internal combustion machine by the electric motor is a matter of time. This dissertation aims to review the overall technological developments which will lead to the design of automobiles with zero emissions. The use of new materials for automobile design, weight reduction, renewable energy sources, regenerative energy from braking are some of the topics that will be discussed. Key technologies such as hydrogen fuel cells, electric cars and biofuels are expected to contribute in the long run. Whereas, hybrid cars are considered as the solution for the near future.Σοφία Γ. Δαΐκο

    A study on the material properties of novel PEGDA/gelatin hybrid hydrogels polymerized by electron beam irradiation

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    Gelatin-based hydrogels are highly desirable biomaterials for use in wound dressing, drug delivery, and extracellular matrix components due to their biocompatibility and biodegradability. However, insufficient and uncontrollable mechanical properties and degradation are the major obstacles to their application in medical materials. Herein, we present a simple but efficient strategy for a novel hydrogel by incorporating the synthetic hydrogel monomer polyethylene glycol diacrylate (PEGDA, offering high mechanical stability) into a biological hydrogel compound (gelatin) to provide stable mechanical properties and biocompatibility at the resulting hybrid hydrogel. In the present work, PEGDA/gelatin hybrid hydrogels were prepared by electron irradiation as a reagent-free crosslinking technology and without using chemical crosslinkers, which carry the risk of releasing toxic byproducts into the material. The viscoelasticity, swelling behavior, thermal stability, and molecular structure of synthesized hybrid hydrogels of different compound ratios and irradiation doses were investigated. Compared with the pure gelatin hydrogel, 21/9 wt./wt. % PEGDA/gelatin hydrogels at 6 kGy exhibited approximately up to 1078% higher storage modulus than a pure gelatin hydrogel, and furthermore, it turned out that the mechanical stability increased with increasing irradiation dose. The chemical structure of the hybrid hydrogels was analyzed by Fourier-transform infrared (FTIR) spectroscopy, and it was confirmed that both compounds, PEGDA and gelatin, were equally present. Scanning electron microscopy images of the samples showed fracture patterns that confirmed the findings of viscoelasticity increasing with gelatin concentration. Infrared microspectroscopy images showed that gelatin and PEGDA polymer fractions were homogeneously mixed and a uniform hybrid material was obtained after electron beam synthesis. In short, this study demonstrates that both the presence of PEGDA improved the material properties of PEGDA/gelatin hybrid hydrogels and the resulting properties are fine-tuned by varying the irradiation dose and PEGDA/gelatin concentration

    High-Dose, Extended-Interval Colistin Administration in Critically Ill Patients: Is This the Right Dosing Strategy? A Preliminary Study

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    In critically ill patients with otherwise untreatable nosocomial infection due to gram-negative bacteria susceptible only to colistin, a high-dose, extended-interval colistin dosing regimen is, according to the pharmacokinetic/pharmacodynamic behavior of the drug, associated with low renal toxicity and high efficacy

    Effect and Safety of Meropenem\u2013Vaborbactam versus Best-Available Therapy in Patients with Carbapenem-Resistant Enterobacteriaceae Infections: The TANGO II Randomized Clinical Trial

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    Introduction: Treatment options for carbapenem-resistant Enterobacteriaceae (CRE) infections are limited and CRE infections remain associated with high clinical failure and mortality rates, particularly in vulnerable patient populations. A Phase 3, multinational, open-label, randomized controlled trial (TANGO II) was conducted from 2014 to 2017 to evaluate the efficacy/safety of meropenem\u2013vaborbactam monotherapy versus best available therapy (BAT) for CRE. Methods: A total of 77 patients with confirmed/suspected CRE infection (bacteremia, hospital-acquired/ventilator-associated bacterial pneumonia, complicated intra-abdominal infection, complicated urinary tract infection/acute pyelonephritis) were randomized, and 47 with confirmed CRE infection formed the primary analysis population (microbiologic-CRE-modified intent-to-treat, mCRE-MITT). Eligible patients were randomized 2:1 to meropenem\u2013vaborbactam (2 g/2 g over 3 h, q8h for 7\u201314 days) or BAT (mono/combination therapy with polymyxins, carbapenems, aminoglycosides, tigecycline; or ceftazidime-avibactam alone). Efficacy endpoints included clinical cure, Day-28 all-cause mortality, microbiologic cure, and overall success (clinical cure + microbiologic eradication). Safety endpoints included adverse events (AEs) and laboratory findings. Results: Within the mCRE-MITT population, cure rates were 65.6% (21/32) and 33.3% (5/15) [95% confidence interval (CI) of difference, 3.3% to 61.3%; P = 0.03)] at End of Treatment and 59.4% (19/32) and 26.7% (4/15) (95% CI of difference, 4.6% to 60.8%; P = 0.02) at Test of Cure;.Day-28 all-cause mortality was 15.6% (5/32) and 33.3% (5/15) (95% CI of difference, 12 44.7% to 9.3%) for meropenem\u2013vaborbactam versus BAT, respectively. Treatment-related AEs and renal-related AEs were 24.0% (12/50) and 4.0% (2/50) for meropenem\u2013vaborbactam versus 44.0% (11/25) and 24.0% (6/25) for BAT. Exploratory risk\u2013benefit analyses of composite clinical failure or nephrotoxicity favored meropenem\u2013vaborbactam versus BAT (31.3% [10/32] versus 80.0% [12/15]; 95% CI of difference, 12 74.6% to 12 22.9%; P < 0.001). Conclusions: Monotherapy with meropenem\u2013vaborbactam for CRE infection was associated with increased clinical cure, decreased mortality, and reduced nephrotoxicity compared with BAT. Clinical Trials Registration: NCT02168946. Funding: The Medicines Company

    Attributable deaths and disability-adjusted life-years caused by infections with antibiotic-resistant bacteria in the EU and the European Economic Area in 2015: a population-level modelling analysis

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    Background: Infections due to antibiotic-resistant bacteria are threatening modern health care. However, estimating their incidence, complications, and attributable mortality is challenging. We aimed to estimate the burden of infections caused by antibiotic-resistant bacteria of public health concern in countries of the EU and European Economic Area (EEA) in 2015, measured in number of cases, attributable deaths, and disability-adjusted life-years (DALYs). Methods: We estimated the incidence of infections with 16 antibiotic resistance–bacterium combinations from European Antimicrobial Resistance Surveillance Network (EARS-Net) 2015 data that was country-corrected for population coverage. We multiplied the number of bloodstream infections (BSIs) by a conversion factor derived from the European Centre for Disease Prevention and Control point prevalence survey of health-care-associated infections in European acute care hospitals in 2011–12 to estimate the number of non-BSIs. We developed disease outcome models for five types of infection on the basis of systematic reviews of the literature. Findings: From EARS-Net data collected between Jan 1, 2015, and Dec 31, 2015, we estimated 671 689 (95% uncertainty interval [UI] 583 148–763 966) infections with antibiotic-resistant bacteria, of which 63·5% (426 277 of 671 689) were associated with health care. These infections accounted for an estimated 33 110 (28 480–38 430) attributable deaths and 874 541 (768 837–989 068) DALYs. The burden for the EU and EEA was highest in infants (aged <1 year) and people aged 65 years or older, had increased since 2007, and was highest in Italy and Greece. Interpretation: Our results present the health burden of five types of infection with antibiotic-resistant bacteria expressed, for the first time, in DALYs. The estimated burden of infections with antibiotic-resistant bacteria in the EU and EEA is substantial compared with that of other infectious diseases, and has increased since 2007. Our burden estimates provide useful information for public health decision-makers prioritising interventions for infectious diseases

    Infection prevention and control measures and tools for the prevention of entry of carbapenem-resistant Enterobacteriaceae into healthcare settings : guidance from the European Centre for Disease Prevention and Control

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    Background: Infections with carbapenem-resistant Enterobacteriaceae (CRE) are increasingly being reported from patients in healthcare settings. They are associated with high patient morbidity, attributable mortality and hospital costs. Patients who are “at-risk” may be carriers of these multidrug-resistant Enterobacteriaceae (MDR-E). The purpose of this guidance is to raise awareness and identify the “at-risk” patient when admitted to a healthcare setting and to outline effective infection prevention and control measures to halt the entry and spread of CRE. Methods: The guidance was created by a group of experts who were functioning independently of their organisations, during two meetings hosted by the European Centre for Disease Prevention and Control. A list of epidemiological risk factors placing patients “at-risk” for carriage with CRE was created by the experts. The conclusions of a systematic review on the prevention of spread of CRE, with the addition of expert opinion, were used to construct lists of core and supplemental infection prevention and control measures to be implemented for “at-risk” patients upon admission to healthcare settings. Results: Individuals with the following profile are “at-risk” for carriage of CRE: a) a history of an overnight stay in a healthcare setting in the last 12 months, b) dialysis-dependent or cancer chemotherapy in the last 12 months, c) known previous carriage of CRE in the last 12 months and d) epidemiological linkage to a known carrier of a CRE. Core infection prevention and control measures that should be considered for all patients in healthcare settings were compiled. Preliminary supplemental measures to be implemented for “at-risk” patients on admission are: preemptive isolation, active screening for CRE, and contact precautions. Patients who are confirmed positive for CRE will need additional supplemental measures. Conclusions: Strengthening the microbiological capacity, surveillance and reporting of new cases of CRE in healthcare settings and countries is necessary to monitor the epidemiological situation so that, if necessary, the implemented CRE prevention strategies can be refined in a timely manner. Creating a large communication network to exchange this information would be helpful to understand the extent of the CRE reservoir and to prevent infections in healthcare settings, by applying the principles outlined here. This guidance document offers suggestions for best practices, but is in no way prescriptive for all healthcare settings and all countries. Successful implementation will result if there is local commitment and accountability. The options for intervention can be adopted or adapted to local needs, depending on the availability of financial and structural resources.peer-reviewe
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