Crescita e caratterizzazione elettrochimica di elettrodi di titania nanostrutturata

La ricerca sulle fonti di energia rinnovabili è un tema di grandissima importanza. Tra queste, l’energia solare è una delle più promettenti. Essa può essere convertita in energia chimica. In questo caso, l’energia solare viene sfruttata per produrre combustibili, i cosiddetti solar fuels, fra i quali spicca l’idrogeno, che non rilascia sostanze inquinanti o gas serra durante la combustione tradizionale o in celle a combustibile. L’idrogeno può essere ottenuto dall’acqua tramite una cella fotoelettrochimica, in cui la luce solare, assorbita da un elettrodo semiconduttivo, permette che avvenga la scissione delle molecole d’acqua. Il materiale più studiato per realizzare i fotoelettrodi è la TiO2, grazie alla resistenza alla corrosione e al basso costo. In questa tesi è descritta la realizzazione, effettuata in laboratorio, di fotoelettrodi di TiO2 e le misure effettuate su di essi. Gli elettrodi sono stati prodotti tramite deposizione fisica di vapori, con la quale è stato possibile realizzare dei film sia compatti che porosi costituiti da nanoparticelle, questi ultimi tramite la condensazione in atmosfera gassosa. Sono stati prodotti elettrodi di vari spessori e in diverse condizioni durante l’evaporazione e sono stati sottoposti a trattamenti termici. Essi sono stati utilizzati come fotoanodi in una cella fotoelettrochimica sulla quale sono state compiute misure per determinare grandezze come la fotocorrente prodotta in condizioni di illuminazione e il flatband potential. Inoltre è stato discusso un modello circuitale con cui è possibile schematizzare la cella ed è stato verificato il suo effettivo funzionamento tramite misure di spettroscopia di impedenza. In questo modo si è cercato di determinare per quali valori di spessore, trattamento termico e condizioni di crescita i campioni dessero le risposte migliori. La morfologia superficiale dei campioni è stata analizzata tramite la microscopia elettronica a scansione (SEM) e quella a forza atomica (AFM)

Dynamic programming for the orienteering problem with time windows

We present an exact optimization algorithm for the Orienteering Problem with Time Windows (OPTW). The algorithm is based on bi-directional and bounded dynamic programming with decremental state space relaxation. We compare different strategies proposed in the literature to guide decremental state space relaxation: our experiments on instances derived from the literature show that there is no dominance between these strategies. We also propose a new heuristic technique to initialize the critical vertex set and we provide experimental evidence of its effectiveness

Column generation for a real world vehicle routing problem

We present an optimization algorithm we developed for a software provider of planning tools for distribution logistics companies. The algorithm computes a daily plan for a heterogeneous fleet of vehicles, that can depart from different depots and must visit a set of customers for delivery operations. Besides multiple capacities and time windows associated with depots and customers, the problem also considers incompatibility constraints between goods, depots, vehicles and customers, maximum route length and durations, upper limits on the number of consecutive driving hours and compulsory drivers' rest periods, the possibility to skip some customers and to use express courier services instead of the given fleet to fulfill some orders, the option of splitting up the orders, the possible existence of pick-up operations to be performed by empty vehicles traveling back to their depots and the possibility of ``open" routes that do not terminate at depots. Moreover, the cost of each vehicle route is computed through a system of fares, depending on the locations visited by the vehicle, the distance traveled, the vehicle load and the number of stops along the route. We developed a column generation algorithm, where the pricing problem is a particular resource constrained elementary shortest path problem, solved through a bounded bi-directional dynamic programming algorithm. We describe how to encode the cost function and the complicating constraints by an appropriate use of resources and we present computational results on real instances obtained from the software company

Left atrial strain in patients with arterial hypertension

Background: Arterial hypertension (HTN) causes left ventricular (LV) cavity dysfunction even if ejection function (EF) remains preserved. Recent studies have shown that diastolic dysfunction and left atrial (LA) dilatation are also associated with myocardial dysfunction. The aim of the present study was to explore the nature of LA longitudinal function disturbances in hypertensive patients with normal LV and LA structure and conventional function parameters.Methods: Peak atrial longitudinal strain (PALS) was evaluated in 78 patients with systemic HTN and preserved EF (≥ 55%) divided in 41 patients with diastolic dysfunction but no hypertrophy (group HTNdd), and 37 patients with no diastolic dysfunction or hypertrophy (group eHTN). Results were compared with those from 38 age and gender-matched healthy controls.Results: Indexed LA area and indexed LA volume were within the normal range and not different between the two patient groups and controls. eHTN group had reduced global PALS (p &lt; 0.001) and four-and two-chamber average PALS (p &lt; 0.001 for both). Similar abnormalities were seen in HTNdd group but to a worse degree (P &lt; 0.01 for both). LV EF was not different between the eHTN and HTNdd groups compared to controls. LV E/e' ratio was the strongest predictor of reduced global PALS in both eHTN and HTNdd groups.Conclusion: Asymptomatic untreated HTN patients with preserved LVEF and normal diastolic function have compromised LA strain despite normal cavity size, consistent with preclinical LA myocardial dysfunction.</p

Impact of the Type of Dialysis on Time to Transplantation: Is It Just a Matter of Immunity?

Background: Renal transplantation represents the therapeutic gold standard in patients with end stage renal disease (ESRD). Still the role of pre-transplant dialysis in affecting time to transplantation has yet to be determined. We wanted to verify whether the type of renal replacement therapy (hemodialysis vs. peritoneal dialysis) affects time to transplantation and to identify clinical features related to the longer time to transplantation. Methods: We performed a retrospective single-center observational study on patients who had received a transplant in the Bologna Transplant Unit from 1991 to 2019, described through the analysis of digital transplant list documents for sex, age, body mass index (BMI), blood group, comorbidities, underlying disease, serology, type of dialysis, time to transplantation, Panel Reactive Antibodies (PRA) max, number of preformed anti Human Leukocyte Antigens (HLA) antibodies. A p-value &lt; 0.05 was considered statistically significant. Results: In the 1619 patients analyzed, we observed a significant difference in time to transplant, PRA max and Preformed Antibodies Number between patients who received Hemodialysis (HD) and Peritoneal dialysis (PD). Then we performed a multiple regression analysis with all the considered factors in order to identify features that support these differences. The clinical variables that independently and directly correlate with longer time to transplantation are PRA max (p &lt; 0.0001), Antibodies number (p &lt; 0.0001) and HD (p &lt; 0.0001); though AB blood group (p &lt; 0.0001), age (p &lt; 0.003) and PD (p &lt; 0.0001) inversely correlate with time to transplantation. Conclusions: In our work, PD population received renal transplants in a shorter period of time compared to HD and turned out to be less immunized. Considering immunization, the type of dialysis impacts both on PRA max and on anti HLA antibodies

RV longitudinal deformation correlates with myocardial fibrosis in patients with end-stage heart failure

Objectives This study was performed to determine the accuracy of right ventricular (RV) longitudinal strain (LS) in predicting myocardial fibrosis in patients with severe heart failure (HF) undergoing heart transplantation. Background RVLS plays a key role in the evaluation of its systolic performance and clinical outcome in patients with refractory HF. Methods We studied 27 patients with severe systolic HF (ejection fraction 25% and New York Heart Association functional class III to IV, despite full medical therapy and cardiac resynchronization therapy) using echocardiography before heart transplantation. RV free wall LS, right atrial LS, sphericity index (SI), and tricuspid annular plane systolic excursion (TAPSE) were all measured. Upon removal of the heart, from the myocardial histologic analysis, the ratio of the fibrotic to the total sample area determined the extent of fibrosis (%). Results RV myocardial fibrosis correlated with RV free wall LS (r = 0.80; p < 0.0001), SI (r = 0.42; p = 0.01) and VO max (r = -0.41; p = 0.03), with a poor correlation with TAPSE (r = -0.34; p = 0.05) and right atrial LS (r = -0.37; p = 0.03). Stepwise multivariate analysis showed that RV free wall LS (β = 0.701, p < 0.0001) was independently associated with RV fibrosis (overall model R= 0.64, p < 0.0001). RV free wall LS was the main determinant of myocardial fibrosis. In the subgroup of patients with severe RV fibrosis, RV free wall LS had the highest diagnostic accuracy for detecting severe myocardial fibrosis (area under the curve = 0.87; 95% confidence interval: 0.80 to 0.94). Conclusions In late-stage HF patients, the right ventricle is enlarged, with reduced systolic function due to significant myocardial fibrosis. RV free wall myocardial deformation is the most accurate functional measure that correlates with the extent of RV myocardial fibrosis and functional capacity

EU project "Cheap-GSHPs": the geoexchange field laboratory

Abstract The Molinella test site is the open-air laboratory of the EU project entitled "Cheap-GSHPs: Cheap and Efficient Application of Reliable Ground Source Heat Exchangers and Pumps". Here, innovative helical heat baskets and steel coaxial probes are installed next to the traditional double-U. The tests involve the probes design as well as materials and drilling techniques and machines, therefore the newly developed GSHEs can be directly compared with the traditional ones with respect to technical issues and energetic performances. The Molinella test site therefore represents a very extraordinary possibility to improve the knowledge of heat transfer processes in shallow geo-exchange systems

Efficacy of SARS-CoV-2 Vaccination in Dialysis Patients: Epidemiological Analysis and Evaluation of the Clinical Progress

This study investigated the impact of the fourth COVID-19 pandemic wave on dialysis patients of Romagna territory, assessing the associations of vaccination status with infection risk, clinical severity and mortality. From November 2021 to February 2022, an epidemiological search was conducted on 829 patients under dialysis treatment for at least one month. The data were then analyzed with reference to the general population of the same area. A temporal comparison was also carried out with the previous pandemic waves (from March 2020 to October 2021). The epidemiological evolution over time in the dialysis population and in Romagna citizens replicated the global trend, as the peak of the fourth wave corresponded to the time of maximum diffusion of omicron variant (B.1.1.529). Of 771 prevalent dialysis patients at the beginning of the study, 109 (14.1%) contracted SARS-CoV-2 infection during the 4-month observation period. Vaccine adherence in the dialysis population of the reference area was above 95%. Compared to fully or partially vaccinated subjects, the unvaccinated ones showed a significantly higher proportion of infections (12.5% vs. 27.0% p = 0.0341), a more frequent need for hospitalization (22.2% vs. 50.0%) and a 3.3-fold increased mortality risk. These findings confirm the effectiveness of COVID-19 vaccines in keeping infectious risk under control and ameliorating clinical outcomes in immunocompromised patients

A public data archive for the Italian radio telescopes

The amount of data delivered by modern instrumentation and observing techniques is bringing radio astronomy in the era of Big Data, and the nowadays widely adopted Open Data policies allow free and open access to data from many radio astronomy facilities. A fundamental ingredient to enable Open Science in the radio astronomical community and to engage also public participation (the so called Citizen Science) is thus the availability of public archives in which data can be accessed and searched with modern software tools. A web-based, VO-compliant public archive has been built to host data from the Italian radio telescopes managed by the National Institute for Astrophysics (INAF). The archive main features consist in the capability to handle the various types of data coming from the different observing instrumentation at the telescopes; the adoption of a policy to guarantee the data proprietary period; the accessibility of data through a web interface and the adoption of VO standards to allow for successful scientific exploitation of the archive itself in the data mining era. We present the progress status of the public Data Archive for the Italian radio telescopes being developed to provide the international community with a state-of-the-art archive for radio astronomical data