91 research outputs found
Study of light-trapping enhanced quantum dot solar cells based on electrical and optical numerical simulations
No full textWe study InAs/GaAs quantum dot solar cells exploiting light trapping approaches to enhance the interband light harvesting efficiency of quantum dots. A realistic thin-film structure including a nanostructured anti-reflection coating and a planar reflector is investigated both from the optical and electrical standpoint, based on finite difference time domain electromagnetic simulations and on quantum-dot-aware transport simulations. The photovoltaic efficiency of quantum dot solar cells and reference bulk cells is analyzed for various configurations, from the single-pass -wafer-based- one to the thin-film one approaching the ideal Lambertian limit. We show that light-trapping enhancement, combined with QD selective doping, may allow the quantum dot cell to achieve photovoltaic efficiency higher than its bulk counterpar
Economic analysis of waste management systems in Europe
No full textThe paper sketches the main regulatory economic issues characterizing waste management policies
in the EU context. On the background, the evolution of solid waste management (SWM) policies that has
increasingly shifted attention from end-of-pipe management (waste collection and disposal) to prevention and
value-chain management.
Economic issues regard in particular evaluation of waste management options; "market failures" in the WM
industry and dimensions of general interest that require public regulation; industrial organization of WM
services and patterns of private sector involvement; use of economic instruments and market mechanisms for
achieving WM targets. These issues arerapidly presented in their theoretical implications and later discussed
on the basis of experience in EU countrie
Nanostructures for light management in thin-film GaAs quantum dot solar cells
No full textWe have investigated structures for thin-film GaAs quantum dot solar cells. Light trapping at quantum dot bands is realized by a triangular grating reflector whose aspect ratio is identified as the main design parameter
Fabrication of nanocrystalline supersaturated W–Al alloys with enhanced thermal stability and high sinterability
No full textIn this work, nanocrystalline W–Al alloys (up to 20 at.% of Al) were produced by high energy ball milling and powder microstructural evolution was investigated as a function of milling time. It was found that, regardless of the composition, alloys crystallite size progressively decreases and stabilizes around a value of about 10–15 nm after 70–100 h of mechanical treatment. The aluminum dissolution into the bcc W lattice was confirmed by DSC, SEM, and TEM. The formation of intermetallic compounds was detected neither during ball milling nor after thermal treatments up to 1450 °C. Sintering behavior of mechanically alloyed W–Al alloys was tested under pressureless conditions, and a significant improvement in terms of sinterability with respect to pure W was observed. Along with favoring the sintering process, the addition of Al also resulted in a notable enhancement of the coarsening resistance. Indeed, the analysis of ball-milled pure tungsten after thermal treatment at 1450 °C provided an estimated average crystallite size of about 2 μm, while W80Al20 and W90Al10 alloys retained an average crystallite size of about 70 nm and 60 nm, respectively. Although further work is required to optimize sintering conditions for achieving full density samples, the retaining of the nanostructure marks a significant advancement in the field of W-based alloys.</p
Metabolomics: Which role in asphyxia and sepsis?
No full textMetabolomics is a new “omics” approach concerning the high-throughput identification, quantification and characterization of endogenous and exogenous metabolites. This new technique is gaining consideration upon medical practice improving the single metabolite analysis as well as measuring the response to treatment in intensive care units. However, despite great efforts, very little research has new biomarkers or specific metabolic profiles, which characterize disorders such as asphyxia and sepsis. Here, we point out some of the recent works published in literature regarding the management of these conditions having high mortality and morbidity rates. The purpose of this review is also to highlight the ability of metabolomics to find early biomarkers for these conditions as well as to predict the development of sideeffects due to the therapy. The goal is to demonstrate that the metabolomics technique can be considered a viable option for the study of these conditions, which may help to develop a better care in intensive departments
The safety and security of cultural heritage in zones of war or instability
No full textA nation's cultural heritage represents its past, its present and its path to the future, but for many
years, the cultural heritage in or adjacent to war and conflict zones has been subject to continual
assault, both deliberate and unintended.
This book presents papers delivered at the NATO Advanced Research Workshop entitled “Cultural
Heritage’s safety and security in zone of war or instability”, hosted online by the university of Rome
from 25 - 27 November 2020. NATO has always been a leading player in the protection of cultural
property (CPP) in the areas in which it intervenes, indeed, the protection of cultural property and
common heritage is part of NATO’s core values. In addition to this, the illicit trade in antiquities and
archaeological finds represents another danger to cultural heritage and can help to finance the
terrorist groups that manage to seize these assets. The workshop aimed to explore ways to protect
and safeguard cultural heritage in war zones or from terrorist attacks, and a group of international
experts were invited to contribute presentations on selected topics of direct relevance to the
processes in NATO with regard to CPP. Topics included: the experiences of international institutions;
conservation and restoration; and countermeasures, technologies and examples of successful
interventions.
The book raises awareness of the importance of safeguarding cultural heritage and sets out ways of
tackling the problem. It will be of interest to all those working in the field of protecting cultural heritage
in unstable areas
Outcome of cardiac surgery in patients with low preoperative ejection fraction
No full textBackground: In patients undergoing cardiac surgery, a reduced preoperative left ventricular ejection fraction (LVEF) is common and is associated with a worse outcome. Available outcome data for these patients address specific surgical procedures, mainly coronary artery bypass graft (CABG). Aim of our study was to investigate perioperative outcome of surgery on patients with low pre-operative LVEF undergoing a broad range of cardiac surgical procedures. Methods: Data from patients with pre-operative LVEF ≤40 % undergoing cardiac surgery at a university hospital were reviewed and analyzed. A subgroup analysis on patients with pre-operative LVEF ≤30 % was also performed. Results: A total of 7313 patients underwent cardiac surgery during the study period. Out of these, 781 patients (11 %) had a pre-operative LVEF ≤40 % and were included in the analysis. Mean pre-operative LVEF was 33.9 ± 6.1 % and in 290 patients (37 %) LVEF was ≤30 %. The most frequently performed operation was CABG (31 % of procedures), followed by mitral valve surgery (22 %) and aortic valve surgery (19 %). Overall perioperative mortality was 5.6 %. Mitral valve surgery was more frequent among patients who did not survive, while survivors underwent more frequently CABG. Post-operative myocardial infarction occurred in 19 (2.4 %) of patients, low cardiac output syndrome in 271 (35 %). Acute kidney injury occurred in 195 (25 %) of patients. Duration of mechanical ventilation was 18 (12-48) hours. Incidence of complications was higher in patients with LVEF ≤30 %. Stepwise multivariate analysis identified chronic obstructive pulmonary disease, pre-operative insertion of intra-aortic balloon pump, and pre-operative need for inotropes as independent predictors of mortality among patients with LVEF ≤40 %. Conclusions: We confirmed that patients with low pre-operative LVEF undergoing cardiac surgery are at higher risk of post-operative complications. Cardiac surgery can be performed with acceptable mortality rates; however, mitral valve surgery, was found to be associated with higher mortality rates in this population. Accurate selection of patients, risk/benefit evaluation, and planning of surgical and anesthesiological management are mandatory to improve outcome
Metabolomics and Microbiomics: New Potential Strategies in Chronic Pain Syndrome
No full textChronic pain affects almost 20% of the European adult population and it significantly reduces patients' quality of life. Chronic pain is considered a multidimensional experience determined by the interaction of several genetic and environmental factors. The effect of specific genetic contributions is often unclear, and the interpretation of the results from studies focused on genetic influences on pain has been complicated by the existence of multiple pain phenotypes. A step forward from genetics could be given by the application of metabolomics and microbiomics tools. Metabolomics is a powerful approach for hypothesis generation in biology, and it aims to analyze low molecular weight compounds, either metabolic intermediates or metabolic end-products, resulting from human or microbial metabolism. Microbiomics is a fast-growing field in which all the microbes are examined together, and as a result, its perturbation may indicate the development of chronic diseases. By applying these methodologies for the study of chronic pain, several differences have been identified. The alteration of the choline-PAF pathway is an intriguing finding recognized by several groups. In our opinion, metabolomics and microbiomics techniques will allow significant progress into the medical field. Patients may benefit from the possibility of being stratified and classified based on their metabolic and microbial profile, which, in the next future, may lead to personalized therapy
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