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Alfa Romeo Avio is involved in the overhaul process of the Pratt & Whitney of Canada PT6T-6 for the helicopter fleet of the Italian Army and civil services. The overhauled power sections suffered from a high rejection rate (about 40 percent) for low performance at the acceptance test. Alfa Romeo Avio R&D investigated the causes and developed a method to reduce the rejection rate. A first contribution to the decision support method for the selection of the optimal engine configuration can be obtained from engine thermodynamic cycle simulation, which gives indications on the behavior of the average overhauled power section. In this paper the authors also describe a statistical model based on a cause/effect correlation between power section assembly variables and performance parameters. A simulation procedure, based on the statistical model, estimates the influence of the configuration assembly data on the power section performance parameters. A careful application of both statistical and thermodynamic models gives predictions on the optimum matching of turbine nozzle size to reach the target performance at the engine acceptance test. The method has been tested on the field during the last two years and a reduction in the rejection rate at the acceptance test to 18 percent has been obtained.

The aerodynamic design of a centrifugal compressor for technologically advanced small aeroengines requires more and more the use of sophisticated computational tools in order to meet the goals successfully at minimum cost development. The objective of the present work is the description of the procedure adopted to design a transonic impeller having 1.31 relative Mach number at the inducer tip, 45 deg back-swept exit blade angle, and a tip speed of 636 m/s. The optimization of the blade shape has been done by analyzing the aerodynamic flowfield by extensive use of a quasi-three-dimensional code and a fully three-dimensional Euler solver based on a time-marching approach and a finite volume discretization. Testing has been done on the impeller-only configuration, using a compressor rig that simulates real engine hardware, i.e., having an S-shaped air-intake. The overall performance of the impeller is presented and discussed.

An advanced low-NOx combustor is studied experimentally in the frame of the recent European Program EEFAE (Efficient and Environmentally Friendly Aero-Engine) for the CLEAN (Component vaLidator for Environmentally-friendly Aero-eNgine) demonstrator. The experimental measurements are compared with model predictions obtained using a 3-D computational fluid dynamics (CFD) proprietary code properly coupled with a numerical tool called Kinetic Post-Processor (KPP). One of the aims of this paper is also to describe a methodology for computing steady turbulent reacting flows in complex shape combustors: the thermo-fluid dynamics results of the CFD code are processed by the KPP with the use of detailed kinetics for predicting pollutant emissions, with special emphasis to nitrogen oxides. The comparisons between experimental measurements and model predictions indicate the current limitations of the procedure but also the possibilities of this powerful tool. From the kinetics point of view, the need for accurate high-pressure experimental data on NOx formation is also highlighted. [ABSTRACT FROM AUTHOR]

Background & Aims: SARS-Cov-2 infection manifests as a wide spectrum of clinical presentation and even now, despite the global spread of the vaccine, contagiousness is still elevated. The aim of the study was the evaluation of the impact of liver fibrosis assessed by FIB-4 and liver impairment, assessed by cytolysis indices, on intrahospital mortality in COVID-19 subjects., Methods: This is a retrospective observational cohort study, which involved 23 COVID Hospital Units in Campania Region, Italy. Exposure variables were collected during hospital admission and at discharge. According to FIB-4 values, we subdivided the overall population in three groups (FIB-4<1.45; 1.453.25), respectively group 1,2,3., Results: At the end of the study, 938 individuals had complete discharged/dead data. At admission, 428 patients were in group 1 (45.6%), 387 in group 2 (41.3%) and 123 in group 3 (13.1%). Among them, 758 (81%) subjects were discharged, while the remaining 180 (19%) individuals died. Multivariable Cox's regression model showed a significant association between mortality risk and severity of FIB-4 stages (group 3 vs group 1, HR 2.12, 95%CI 1.38-3.28, p<0.001). Moreover, Kaplan-Meier analysis described a progressive and statistically significant difference (p<0.001 Log-rank test) in mortality according to FIB-4 groups. Among discharged subjects, 507 showed a FIB-4<1.45 (66.9%, group 1), 182 a value 1.453.25 (9.0%, group 3). Among dead subjects, 42 showed a FIB-4<1.45 (23.3%, group 1), 62 a value 1.453.25 (42.3%, group 3)., Conclusions: FIB-4 value is significantly associated with intrahospital mortality of COVID-19 patients. During hospitalization, particularly in patients with worse outcomes, COVID-19 seems to increase the risk of acute progression of liver damage., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Galiero et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background and Aims: The COVID-19 pandemic, caused by the novel coronavirus SARS-CoV-2, has fundamentally reshaped the landscape of global public health, with some people suffering more adverse clinical outcomes than others. The aim of this study is to deepen our understanding of the specific impact of acute kidney injury (AKI) on the in-hospital mortality in octogenarian patients with COVID-19., Methods: This is a prospective observational cohort study, which involved 23 COVID-19 hospital units in the Campania Region, Italy. Exposure variables were collected during hospital admission and at discharge. Only patients aged ≥80 years were deemed eligible for the study., Results: 197 patients were included in the study (median age 83.0 [82.0-87.0] years; 51.5% men), with a median duration of hospitalization of 15.0 [8.0-25.0] days. From the multivariable Cox regression analysis, after the application of Šidák correction, only the respiratory rate (HR 1.09, 95% CI: 1.04 to 1.14; p < 0.001) and AKI development (HR: 3.40, 95% CI: 1.80 to 6.40; p < 0.001) were independently associated with the primary outcome. Moreover, the Kaplan-Meier analysis showed a significantly different risk of in-hospital mortality between patients with and without AKI (log-rank: <0.0001)., Conclusions: In our investigation, we identified a significant association between AKI and mortality rates among octogenarian patients admitted for COVID-19. These findings raise notable concerns and emphasize the imperative for vigilant monitoring of this demographic cohort.

Background: Acute respiratory distress syndrome (ARDS) is one of the most severe complications of SARS-CoV-2 infection. Non-Invasive Respiratory Support (NRS) as Continuous Positive Airway Pressure (CPAP) and/or Non-Invasive Ventilation (NIV) has been proven as effective in the management of SARS-CoV-2-related ARDS. However, the most appropriate timing for start NRS is unknown., Methods: We conducted a prospective pilot study including all consecutive patients who developed moderate SARS-CoV-2-related ARDS during hospitalization. Patients were randomly divided into two intervention groups according to ARDS severity (assessed by PaO 2 /FiO 2 -P/F) at NRS beginning: group A started CPAP/NIV when P/F was ≤ 200 and group B started CPAP/NIV when P/F was ≤ 150. Eligible patients who did not give their consent to CPAP/NIV until the severe stage of ARDS and started non-invasive treatment when P/F ≤ 100 (group C) was added. The considered outcomes were in-hospital mortality, oro-tracheal intubation (OTI) and days of hospitalization., Results: Among 146 eligible patients, 29 underwent CPAP/NIV when P/F was ≤ 200 (Group A), 68 when P/F was ≤ 150 (Group B) and 31 patients agreed to non-invasive treatment only when P/F was ≤ 100 (Group C). Starting NRS at P/F level between 151 and 200 did not results in significant differences in the outcomes as compared to treatment starting with P/F ranging 101-150. Conversely, patients undergone CPAP/NIV in a moderate stage (P/F 101-200) had a significantly lower in-hospital mortality rate (13.4 vs. 29.0%, p = 0.044) and hospitalization length (14 vs. 15 days, p = 0.038) than those in the severe stage (P/F ≤ 100). Age and need for continuous ventilation were independent predictors of CPAP/NIV failure., Conclusions: Starting CPAP/NIV in patients with SARS-CoV-2-related ARDS in moderate stage (100 > P/F ≤ 200) is associated to a reduction of both in-hospital mortality and hospitalization length compared to the severe stage (P/F ≤ 100). Starting CPAP/NIV with a P/F > 150 does not appear to be of clinical utility., (© 2022. The Author(s).)

Background. Evidence has shown a close association between COVID-19 infection and renal complications in both individuals with previously normal renal function and those with chronic kidney disease (CKD). Methods. The aim of this study is to evaluate the in-hospital mortality of SARS-CoV-2 patients according to their clinical history of CKD or estimated glomerular filtration rate (eGFR). This is a prospective multicenter observational cohort study which involved adult patients (≥18 years old) who tested positive with SARS-CoV-2 infection and completed their hospitalization in the period between November 2020 and June 2021. Results. 1246 patients were included in the study, with a mean age of 64 years (SD 14.6) and a median duration of hospitalization of 15 days (IQR 9−22 days). Cox’s multivariable regression model revealed that mortality risk was strongly associated with the stage of renal impairment and the Kaplan−Meier survival analysis showed a progressive and statistically significant difference (p < 0.0001) in mortality according to the stage of CKD. Conclusion. This study further validates the association between CKD stage at admission and mortality in patients hospitalized for COVID-19. The risk stratification based on eGFR allows clinicians to identify the subjects with the highest risk of intra-hospital mortality despite the duration of hospitalization.