Hall Thruster Direct-Drive Assessment and Demonstration

This thesis involves the theoretical and experimental study of the Hall thruster Direct-Drive configuration: a innovative way to deliver power to the electric thrusters and candidate for future propulsion system of spacecraft. The direct connection between the solar array and the thruster anode, made possible by the current development of technology, allows a drastic simplification of the power processing unit of the propulsion system. This has an immediate impact on the propulsion system and its thermal control system which can be consequently lightened. Then, additional mass benefits can be exploited in other parts of the spacecraft such as the electric power system. The work is mainly divided in two parts. The first one assesses in terms of mass reduction the impact that the Direct-Drive configuration entails in the spacecraft systems. Different kind of space missions with different level of Hall thruster power are considered. The second part of thesis concerns an experimental demonstration of a Direct-Drive system supplying the HT-100, the low power electric thruster developed at Alta. The test required the procurement of the solar panel and the design of an electrical filter. By means of simulations with Pspice, a LC filter was developed and then arranged between the solar modules and thruster in order to dampen the current oscillations. This test successfully proved the correct ignition and operations of the thruster, representing in this way the first attempt in Europe of a Direct-Drive demonstration

Metal N,N-dialkylcarbamates as easily available catalytic precursors for the carbon dioxide/propylene oxide coupling under ambient conditions

A series of previously reported homoleptic and non-homoleptic N,N-dialkylcarbamates of a range of non precious metals and N,N-dialkylcarbamate of Al(III) were investigated as easily available and inexpensive catalysts in the solventless synthesis of propylene carbonate (PC) from propylene oxide (PO) and CO2. By operating at atmospheric CO2 pressure at ambient temperature, excellent results were achieved using Ti(O2CNEt2)4, Al(O2CNR2)3 (R = Et, iPr), Cu(O2CNEt2)2 and Sn(O2CNEt2)4, in combination with NBu4X (X = Br or Cl) as a co-catalyst. The reactions of MCl2(O2CNEt2)2 (M = Ti, Zr) with amorphous silica were straightforward through partial release of both chlorido and carbamato ligands, and readily afforded solid materials which were characterized by ICP-OES and EDS analyses, coupled to SEM. These heterogeneous catalytic systems revealed less efficient than the homogeneous counterparts

"Diagnosis on the Dock" project: A proactive screening program for diagnosing pulmonary tuberculosis in disembarking refugees and new SEI model.

Abstract Objective From 2011 to 2017, the total number of refugees arriving in Europe, particularly in Italy, climbed dramatically. Our aim was to diagnose pulmonary TB in migrants coming from the African coast using a clinical-based port of arrival (PoA) screening program. Methods From 2016 to 2018, migrants coming via the Mediterranean Route were screened for body temperature and the presence of cough directly on the dock: if they were feverish with productive cough, their sputum was examined with NAAT; with a dry cough, they underwent Chest-X-ray (CXR). Those migrants with positive NAAT or CXR suggestive for TB were admitted to our ward. In addition, we plotted an SEI simulation of our project to evaluate the epidemiological impact of our screening. Results Out of 33.676 disembarking migrants, 314 (0.9%) had fever and cough: 80 (25.47%) with productive cough underwent NAAT in sputum, and 16 were positive for TB; 234 (74.52%) with dry cough had a CXR examination, and 39 were suggestive of TB, later confirmed by mycobacterial culture. The SEI-new model analysis demonstrated that our screening program significantly reduced TB spreading all over the country. Conclusions For possible future high migrant flows, PoA screening for TB has to be considered feasible and effective in decreasing TB spreading

Thermal decomposition of metal N,N-dialkylcarbamates

Thermogravimetric analysis coupled with IR spectroscopy was used to investigate the thermal stability and decomposition products of N,N-dialkylcarbamates of zirconium(IV), hafnium(IV), and niobium(IV), M(O2CNR2)4. The niobium derivatives were less stable than the corresponding Zr(IV) and Hf(IV) derivatives, and the thermal stability was in the order of R = Et > iPr > Me. XRD analysis of the residue showed the formation of the oxides ZrO2 (tetragonal, P4 2 /nmc), HfO2, (monoclinic, P2 1/c), and Nb2O5 (orthorhombic, Pbam). TEM analysis showed that all the oxides were obtained as nanopowders with a crystal size below 30 nm

Synproportionation Reactions between Copper(II) Trihaloacetates Cu(CX3COO)2 , X = F, Cl, Br, and Copper in the Presence of Carbon Monoxide

The trichloro- and tribromo-acetato derivatives of copper() of general formula Cu2(CX3CO2)4(CX3CO2H)2 have been prepared by exchange reactions from Cu(CF3CO2)2 and CX3CO2H (X = Cl or Br) in a hydrocarbon solvent. The chloro derivative, which has also been obtained from CuO in the presence of CCl3CO2H/(CCl3CO)2O, has been characterized by variable-temperature magnetic measurements and by X-ray diffraction. The trifluoroacetato carbonyl derivative of copper(), Cu(CF3CO2)(CO), has been prepared: (a) by reaction of Cu2O with CF3CO2H/ (CF3CO)2O in the presence of CO; (b) by direct carbonylation of Cu(CF3CO2) in toluene or in the solid state; (c) by synproportionation of Cu(CF3CO2)2 and copper in the presence of CO in MeOH, DME, THF or toluene at room temperature. Solutions of Cu(CCl3CO2)(CO) have been obtained by the synproportionation of Cu2(CCl3CO2)4- (CCl3CO2H)2 and copper under a CO atmosphere in toluene. No carbonyl derivative was observed in solution with Cu2(CBr3CO2)4(CBr3CO2H)2 under similar conditions. On standing, hydrocarbon solutions of Cu(CCl3CO2)(CO) slowly gave CuCl(CO) and a mixed-valence, polynuclear carbonyl derivative of formula [Cu4(CCl3CO2)6(CHCl2CO2H)- (CO)2]n which has fully been characterized by variable temperature magnetic measurements and by X-ray diffraction

The MBRD Dipoles for the Luminosity Upgrade at the LHC: From Prototype Tests to the Series Production

The recombination dipoles MBRD for the High Luminosity upgrade of the Large Hadron Collider (HL-LHC) at CERN are double-aperture superconducting magnets generating a central magnetic field of 4.5 T in a 105 mm diameter bore, directed in the same direction in both apertures. The integrated magnetic field is 35 T-m in a magnetic length of 7.78 m: with respect to the corresponding magnet presently installed in LHC, the aperture is larger, the length is smaller and the central field is higher. The project, currently underway, includes the fabrication by ASG Superconductors and testing at CERN of a short model (1.6 m long), a prototype, and a series of 4 + 2 spare dipoles. The short model was delivered to CERN and successfully tested in a vertical cryostat in summer 2020, reaching nominal current after three quenches in the second thermal cycle, validating most of the mechanical, thermal and electrical design and giving indications for improvements that have been implemented in the prototype, which was completed and delivered to CERN in October 2021. It was tested in October 2022 in its final cold mass, 14 m long, which also includes the two orbit correctors. This contribution reports on key results from the prototype tests and on the further activities related to the construction of the first magnets of the series

The Development of MBRD Magnets, the Separation/Recombination Dipoles for the LHC High Luminosity Upgrade

As part of the high-luminosity upgrade of CERN LHC accelerator project, the National Institute of Nuclear Physics (INFN) in Genoa, Italy, has developed the MBRD separation-recombination dipole, also known as D2, whose function is to bring beams into collision before and after the interaction regions of the CMS and ATLAS experiments. It is a NbTi cos-theta double aperture dipole that generates a 4.5 T field in a 105 mm aperture, with a magnetic length of 7.78 m, and has the specific feature that the magnetic field in the two apertures is oriented in the same direction. The agreements between INFN and CERN, signed in 2016 and 2020, called for the construction of a short model, 1.6 m long, a prototype of final size, and the six series magnets, four of which are to be installed in the tunnel and two spare. After an international tender, the construction of all magnets was awarded to ASG Superconductors. The short model was successfully tested at CERN in a vertical cryostat in August 2020, reaching nominal current after three quenches in the second thermal cycle, validating most of the mechanical, thermal, and electrical design and providing important insights into the improvements that were implemented in the prototype. Testing of the D2 cold mass prototype was performed in October 2022. Its performance was found to be extremely good, with no quenches below nominal current even in the first thermal cycle and showing excellent operating margin in terms of current, ramp rate, and temperature. Although the series magnets were designed to be identical to the prototype, some modifications and tuning improvements, including a small cross-sectional refinement, were implemented and assessed with the construction of the first magnet in the series. This contribution reports all the activities that, based on the short model and prototype experience, led us to the construction of the first series magnet

Clinical characteristics and predictors of death among hospitalized patients infected with SARS-CoV-2 in Sicily, Italy: A retrospective observational study

Since late December 2019, severe acute respiratory syndrome coronavirus 2 has spread across the world, which resulted in the World Health Organization declaring a global pandemic. Coronavirus disease 2019 (COVID-19) presents a highly variable spectrum with regard to the severity of illness. Most infected individuals exhibit a mild to moderate illness (81%); however, 14% have a serious disease and 5% develop severe acute respiratory distress syndrome (ARDS), requiring intensive care support. The mortality rate of COVID-19 continues to rise across the world. Data regarding predictors of mortality in patients with COVID 19 are still scarce but are being actively investigated. The present multicenter retrospective observational study provides a complete description of the demographic and clinical characteristics, comorbidities and laboratory abnormalities in a population of 421 hospitalized patients recruited across eight infectious disease units in Southern Italy (Sicily) with the aim of identifying the baseline characteristics predisposing COVID-19 patients to critical illness or death. In this study, older age, pre-existing comorbidities and certain changes in laboratory markers (such as neutrophilia, lymphocytopenia and increased C-reactive protein levels) at the time of admission were associated with a higher risk of mortality. Male sex, on the other hand, was not significantly associated with increased risk of mortality. Symptoms such as fatigue, older age, a number of co-pathologies and use of continuous positive airway pressure were the most significant contributors in the estimation of clinical prognosis. Further research is required to better characterize the epidemiological features of COVID-19, to understand the related predictors of death and to develop new effective therapeutic strategies