36 research outputs found
Unsteady Flow-Field Unreactive Experimental Characterisation and Velocity Fluctuations Analysis of an Ansaldo Energia Heavy Duty Gas Turbine Burner
No full textMultiphysics modelling of gaseous fission products in the Molten Salt Fast Reactor
No full textThe Molten Salt Fast Reactor (MSFR) is a nuclear reactor concept under development in the framework of the H2020-Euratom project SAMOSAFER. Given its peculiar characteristics as a circulating-fuel reactor, new simulation tools need to be developed and tested for its study. In this work, a multiphysics solver previously developed in OpenFOAM is extended with new functionalities for the analysis of this reactor design. The main focus is the modelling of the behavior of Gaseous Fission Products (GFPs) inside the core and their interactions with a helium bubbling system, foreseen to remove both GFPs and metallic fission products through flotation. On the basis of an Euler-Euler solver able to model the presence of the two phases – namely the liquid fuel and the gaseous bubbles –, a multi-component mixture approach is adopted to simulate the behavior of GFP species in the core, with particular focus on their production, consumption, transport, mass exchange and removal to the off-gas system. The new capabilities are tested on both 2D and 3D MSFR cases, considering Xe-135 as reference nuclide, with focus on the efficiency of the bubbling system in the removal of GFPs from the salt. As main figure of merit of the removal capability, a cycle time related to the extraction of the specie from the system is defined and calculated for different conditions of helium injection. This work constitutes a further advancement in the development of the MSFR concept, extending the modelling capabilities of the previous multiphysics solver. Reliable estimation of the evolution of the gaseous fission products in the reactor core and the related effect of the helium bubbling system is a fundamental requirement for the analysis of the radioactive source term and for the prediction of the overall operating conditions of this innovative nuclear system
Increase in methemoglobin fraction due to the use of glyceryl trinitrate patches in preterm infants: a case report and literature review
No full textBackground: Oxidized heme iron forms methemoglobin (MeHb), impairing the oxygen-binding capability of hemoglobin molecules. Nitric oxide (NO) obtained from glyceryl trinitrate (GTN) patches can cause MeHb formation during limb ischemia topical treatment. This case reports a preterm infant treated with multiple GTN patches who developed elevated MeHb levels, a potential therapy complication. Case presentation: A preterm female newborn (25 + 4 weeks, 560 g) was delivered by cesarean due to maternal HELLP syndrome and intubated for respiratory distress. After developing ischemia in her right hand and foot, GTN patches were applied, but therapy caused a peak in methemoglobin (MeHb) levels, prompting patch removal. MeHb levels normalized after 18 h, and after adjusting therapy, ischemia resolved successfully. Discussion: We report the case of a premature IUGR infant who developed elevated methaemoglobin (MeHb) levels during topical GTN therapy for catheter-related extremity ischemia. While GTN is effective for neonatal ischemia, its dosing, and safety lack consistent guidelines. Elevated MeHb levels, noted in similar cases here reviewed, can impair oxygen exchange, especially in vulnerable preterm infants with immature skin and reduced enzyme activity. Conclusion: This case highlights the need for careful MeHb monitoring and a multidisciplinary approach to manage ischemia safely in neonates undergoing GTN therapy
Performance of a triple GEM detector equipped with Al-GEM foils for X-rays detection
No full textThe study of Soft X-ray emission can be a source of fundamental information, particularly for what concerns tokamaks and plasma diagnostics, but also in general in the fields of high energy and nuclear physics. Detection systems based on Gas Electron Multipliers (GEM) technology can be of particular use in the context of X-ray analyses, being relatively low cost while maintaining good spatial and temporal resolution and capability to sustain high counting rates (up to MHz/mm2). The development of these new and improved detectors is thus of interest, especially in the research about diagnostic and control of machines for fusion energy. In this work, the performance of a new triple-GEM detector, characterized by an aluminum metallic coating on both layers of the GEM foils, is presented and a comparison is made with the more conventional design employing copper coating. The performances of an aluminum-coated GEM (Al-GEM) detector and of a standard copper-coated GEM (Cu-GEM) detector in revealing quasi-monochromatic X-ray beams coming from different fluorescence materials are compared. The Al-GEM detector is shown to less suffer the issue of unwanted background on the signal caused by the presence of copper inside the detector itself. The suppression of this noise source encourages the use of Al-GEM detectors to perform spectroscopy in harsh environments, such as tokamak machines, where soft X-rays are useful probes to control different plasma properties and parameters
Second Attempt for Patent Ductus Arteriosus (PDA) Closure: Room for Acetaminophen? A Retrospective Single-Center Experience at Gaslini Children’s Hospital
No full textBackground: The diagnosis of hemodynamically significant patent ductus arteriosus (hsPDA) occurs in 55% of very low birth weight (VLBW) preterm infants. There is no agreement on the best approach to ensure a quick hsPDA closure. Drug treatment of hsPDA fails in approximately 20% of cases with an increasing risk of prolonged ventilation, BPD, and NEC, as well as the need for surgical duct ligation. This study aims to highlight the efficacy of ibuprofen versus acetaminophen in the case of a second cycle of medical therapy after the failure of the first pharmacological approach for hsPDA closure. Methods: Every VLBW infant admitted to our NICU and treated for hsPDA was included in our retrospective research. Information about the clinical course, hsPDA diagnosis and treatment, and common complications associated with preterm birth was collected. A comparison was made between patients treated with acetaminophen or ibuprofen to assess effectiveness in hsPDA closing. Results: A total of 286 VLBW infants were included. First-course ibuprofen was effective in 87 of 115 infants (75.7%) treated, acetaminophen in 138 of 171 (80.7%). Second-course therapy with ibuprofen was effective in 62.5% of the patients, while acetaminophen was effective in 69.2%. No statistically significant difference was observed in the first-course and second-course success rates. Conclusions: This study confirms that acetaminophen is not inferior to ibuprofen in the closure of hsPDA in VLBW infants. Our data demonstrate that a second course of medical therapy after the failure of the first course could help close the majority of hsPDA cases without surgery
Data Analysis and Tomographic Reconstruction via X-Ray Measurements With a GEM Detector at the High-Voltage Padova Test Facility
No full textIn the context of magnetic confinement fusion, the Megavolt ITER Injector and Concept Advancement (MITICA) project is supported by another experiment called High-Voltage Padova Test Facility (HVPTF): a device designed to improve the knowledge of high voltage holding in a vacuum. HVPTF includes a vacuum chamber containing two electrodes separated by an insulator or a vacuum gap, across which electrical discharges can develop. The electrodes are powered by two independent Cockcroft-Walton power supplies, allowing for a total voltage difference up to 800 kV. The current, voltage, and pressure inside the chamber are monitored at a sampling rate of 100 Hz. Studying the physics behind electrical discharges is fundamental to prevent their development in MITICA, where they can lead to structural damage to the experimental components. For this reason, in April 2022, a gas electron multiplier (GEM) detector was installed at HVPTF, allowing to perform X-ray measurements resolved in time, space, and energy at high rates ( >1 MHz ) without incurring severe pile-up problems. This work describes the analysis of data coming from current, voltage, and pressure sensors, and the X-ray GEM (XR-GEM) detector at HVPTF during two 2022 experimental campaigns. Correlations between sensor signals with the X-ray measurements have been highlighted. Experimental results indicate the presence of characteristic X-ray emissions from anode atoms during electrical discharge events in the needle-plane electrode configuration. An algorithm was developed for generating synthetic detector data based on user-defined X-ray emissions within the vacuum chamber and performing tomographic reconstructions using actual or synthetic detector data. Preliminary results indicate possible gas emissions from the anode's surface during electrical discharge events
Development of a GEM based diagnostic for Soft X-ray measurements resolved in space, time, and energy at RFX-mod2
No full textDevelopment of a Triple-GEM detector with strip readout and GEMINI chip for X rays and neutron imaging
No full textThermal neutron imaging can be a useful tool in the study of the internal structure of an object. The different attenuation properties of the materials with respect to X rays give rise to different interactions and the result is a complementary non-destructive analysis, which can provide important additional information. This technique has been successfully employed in different areas of work, especially in material science and cultural heritage studies. This paper describes the development of a new detection system and its characterization performed with X ray emissions. The system features the use of a gaseous detector, based on the Gas Electron Multiplier technology, and a fully digital electronic readout, with a combination of custom-made ASICs (called GEMINI) and FPGA boards, enabling fast single photon counting. The detector can be thus used directly for X ray imaging, while the addition of a suitable converter in its active volume will allow for detection of neutrons and for reconstruction of their tracks. The readout system is based on a x -y strip structure and features the reconstruction of single events through the center of mass methodology, allowing for accurate tomography, with sub-mm spatial resolution, in combination with sub-ms time resolution and high rate capabilities (up to MHz/mm2)
Design status of the neutron and gamma-ray diagnostics for the Divertor Tokamak Test facility
No full textIn the frame of the design activities of the Divertor Tokamak Test (DTT) facility the development of a comprehensive set of neutron and gamma-ray diagnostics is on-going in order to enable measurements of: neutron yield, neutron yield rate, neutron emissivity over a poloidal section through the plasma; neutron emission spectrum; runaway electrons induced bremsstrahlung radiation and gamma-ray emission from reactions between fast ions and plasma impurities. The present paper provides an overview of the DTT neutron and gamma-ray diagnostics and describes the present status of their design including main components and interfaces, detector types and performances
