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Background: Intraprocedural catheter tip location is currently recommended. Intracavitary EGC and ultrasound are the preferred methods of tip location for catheters with their tip in the superior vena cava or in the right atrium. Though, the best method of intraprocedural tip location for catheters with their tip in the inferior vena cava is still uncertain. One possibility is to visualize the subdiaphragmatic inferior vena cava by ultrasound, using either the transhepatic or the subxiphoid view. Methods: In this prospective study, we compared two different ultrasound windows for the visualization of the inferior vena cava (transhepatic vs subxiphoid) for the purpose of localizing the catheter tip during the insertion of femorally inserted central catheters. Results: We studied 249 consecutive insertions of central catheters via the superficial femoral vein. Intraprocedural location of the catheter tip was performed by ultrasound, using both transhepatic and subxiphoid view. Visualization of the inferior vena cava was possible only in 81 cases (32.5%) with the subxiphoid view, but it was always possible in all 249 cases with the transhepatic view. The catheter tip was localized in 15 patients out of 81 with the subxiphoid view (18.5%); the transhepatic view allowed the visualization of the tip in all 249 patients. Conclusions: The applicability of the subxiphoid window has several limitations, both in terms of visualization of the inferior vena cava and localization of the catheter tip. The transhepatic view should be the preferred method for intraprocedural ultrasound localization of the catheter tip in the inferior vena cava.

Background: A correlation between unsuccessful noninvasive ventilation (NIV) and poor outcome has been suggested in de-novo Acute Respiratory Failure (ARF) patients. Consequently, it is of paramount importance to identify accurate predictors of NIV outcome. The aim of our preliminary study is to evaluate the Diaphragmatic Thickening Fraction (DTF) and the respiratory rate/DTF ratio as predictors of NIV outcome in de-novo ARF patients. Methods: Over 36 months, we studied patients admitted to the emergency department with a diagnosis of de-novo ARF and requiring NIV treatment. DTF and respiratory rate/DTF ratio were measured by 2 trained operators at baseline, at 1, 4, 12, 24, 48, 72 and 96 h of NIV treatment and/or until NIV discontinuation or intubation. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the ability of DTF and respiratory rate/DTF ratio to distinguish between patients who were successfully weaned and those who failed. Results: Eighteen patients were included. We found overall good repeatability of DTF assessment, with Intra-class Correlation Coefficient (ICC) of 0.82 (95% confidence interval 0.72–0.88). The cut-off values of DTF for prediction of NIV failure were < 36.3% and < 37.1% for the operator 1 and 2 (p < 0.0001), respectively. The cut-off value of respiratory rate/DTF ratio for prediction of NIV failure was > 0.6 for both operators (p < 0.0001). Conclusion: DTF and respiratory rate/DTF ratio may both represent valid, feasible and noninvasive tools to predict NIV outcome in patients with de-novo ARF. Trial registration ClinicalTrials.gov Identifier: NCT02976233, registered 26 November 2016.

Objective: Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2) infection may yield a hypercoagulable state with fibrinolysis impairment. We conducted a single-center observational study with the aim of analyzing the coagulation patterns of intensive care unit (ICU) COVID-19 patients with both standard laboratory and viscoelastic tests. The presence of coagulopathy at the onset of the infection and after seven days of systemic anticoagulant therapy was investigated. Patients and methods: Forty consecutive SARS-CoV-2 patients, admitted to the ICU of a University hospital in Italy between 29th February and 30th March 2020 were enrolled in the study, providing they fulfilled the acute respiratory distress syndrome criteria. They received full-dose anticoagulation, including Enoxaparin 0.5 mg·kg-1 subcutaneously twice a day, unfractionated Heparin 7500 units subcutaneously three times daily, or low-intensity Heparin infusion. Thromboelastographic (TEG) and laboratory parameters were measured at admission and after seven days. Results: At baseline, patients showed elevated fibrinogen activity [rTEG-Ang 80.5° (78.7 to 81.5); TEG-ACT 78.5 sec (69.2 to 87.9)] and an increase in the maximum amplitude of clot strength [FF-MA 42.2 mm (30.9 to 49.2)]. No alterations in time of the enzymatic phase of coagulation [CKH-K and CKH-R, 1.1 min (0.85 to 1.3) and 6.6 min (5.2 to 7.5), respectively] were observed. Absent lysis of the clot at 30 minutes (LY30) was observed in all the studied population. Standard coagulation parameters were within the physiological range: [INR 1.09 (1.01 to 1.20), aPTT 34.5 sec (29.7 to 42.2), antithrombin 97.5% (89.5 to 115)]. However, plasma fibrinogen [512.5 mg·dl-1 (303.5 to 605)], and D-dimer levels [1752.5 ng·ml-1 (698.5 to 4434.5)], were persistently increased above the reference range. After seven days of full-dose anticoagulation, average TEG parameters were not different from baseline (rTEG-Ang p = 0.13, TEG-ACT p = 0.58, FF-MA p = 0.24, CK

This article provides additional data on the application of early coagulation support protocol in the management of major trauma patients. Data come from a retrospective analysis reported in the article “Early coagulation support protocol: a valid approach in real-life management of major trauma patients. Results from two Italian centres” [1]. Data contain information about the relationship between differences in resource use and mortality outcomes, and patient demographic and clinical features at presentation. Furthermore, a comparison between resource consumption, the probability of multiple transfusions and the mortality outcomes among propensity-score matched patients is reported.

BACKGROUND: This study aims to ascertain whether (1) an educational program is sufficient to achieve adequate Diaphragm Ultrasound (DUS) assessments on healthy volunteers and (2) combining a video tutorial with a practical session is more effective in making learners capable to obtain accurate DUS measurements, as opposed to sole video tutorial. RESULTS: We enrolledstep 1: 172 volunteers naïve to ultrasound. After watching a video tutorial, a questionnaire was administered and considered to be passed when at least 70% of the questions were correctly answered. Course participants who passed the theoretical test were randomized to either intervention or control group. Learners randomized to the interventional group underwent to a practical training, tutored by an expert, before accessing DUS examination. Participants randomized to the control group directly accessed DUS examination, without any practical training. DUS measurements by learners and tutors were recorded and checked for accuracy, according to predefined criteria. Detection of both acoustic windows and accurate DUS assessment was achieved by 83.7% learners of the intervention group while 3.5% only among controls (p < 0.0001). The subcostal view of the diaphragm was correctly identified by 92% and 65% learners in the intervention and control groups, respectively (p < 0.0001) while the apposition zone by 86% and 71% learners, respectively (p = 0.026). An accurate diaphragm displacement (DD) measurement was obtained by 91% and 45% learners in the intervention and control groups, respectively (p < 0.0001) while an accurate thickening fraction (TF) measurement by 99% and 21%, respectively (p < 0.0001). DD measurements by both groups of learners were significantly correlated with those assessed by expert tutors; however, a significant improvement of measurement accuracy was found in learners randomized to receive also the practical training, compared to controls. CONCLUSIONS: A combined approach con

Rationale: High-flow nasal cannula (HFNC) and helmet noninvasive ventilation (NIV) are used for the management of acute hypoxemic respiratory failure.Objectives: Physiological comparison of HFNC and helmet NIV in patients with hypoxemia.Methods: Fifteen patients with hypoxemia with PaO2/FiO2 < 200 mm Hg received helmet NIV (positive end-expiratory pressure ≥ 10 cm H2O, pressure support = 10-15 cm H2O) and HFNC (50 L/min) in randomized crossover order. Arterial blood gases, dyspnea, and comfort were recorded. Inspiratory effort was estimated by esophageal pressure (Pes) swings. Pes-simplified pressure-time product and transpulmonary pressure swings were measured.Measurements and Main Results: As compared with HFNC, helmet NIV increased PaO2/FiO2 (median [interquartile range]: 255 mm Hg [140-299] vs. 138 [101-172]; P = 0.001) and lowered inspiratory effort (7 cm H2O [4-11] vs. 15 [8-19]; P = 0.001) in all patients. Inspiratory effort reduction by NIV was linearly related to inspiratory effort during HFNC (r = 0.84; P < 0.001). Helmet NIV reduced respiratory rate (24 breaths/min [23-31] vs. 29 [26-32]; P = 0.027), Pes-simplified pressure-time product (93 cm H2O ⋅ s ⋅ min-1 [43-138] vs. 200 [168-335]; P = 0.001), and dyspnea (visual analog scale 3 [2-5] vs. 8 [6-9]; P = 0.002), without affecting PaCO2 (P = 0.80) and comfort (P = 0.50). In the overall cohort, transpulmonary pressure swings were not different between treatments (NIV = 18 cm H2O [14-21] vs. HFNC = 15 [8-19]; P = 0.11), but patients exhibiting lower inspiratory effort on HFNC experienced increases in transpulmonary pressure swings with helmet NIV. Higher transpulmonary pressure swings during NIV were associated with subsequent need for intubation.Conclusions: As compared with HFNC in hypoxemic respiratory failure, helmet NIV improves oxygenation, reduces dyspnea, inspiratory effort, and simplified pressure-time product, with similar transpulmonary pressure swings, PaCO2, and comfort.

Introduction: Early coagulation support (ECS) includes prompt infusion of tranexamic acid, fibrinogen concentrate, and packed red blood cells for initial resuscitation of major trauma patients. The aim of this study was to determine the effects, in terms of blood product consumption, length of stay, and in-hospital mortality, of the ECS protocol, compared to the massive transfusion protocol (MTP) in the treatment of major trauma patients. Patients and methods: A retrospective analysis was conducted using the registry data of two Italian trauma centres. Adult major trauma patients with, or at risk of, active bleeding who were managed according to the MTP during the years 2011–2012, or the ECS protocol during the years 2013–2014 and were considered at risk of multiple transfusions, were enrolled. The primary endpoint was to determine whether the ECS protocol reduces the use of blood products in the acute management of trauma patients. Secondary endpoints were the outcome measures of length of stay in ICU, length of stay in hospital, and mortality at 24-hours and 28-days after hospital admission. Results: Among the 518 major trauma patients admitted to the trauma centres during the study period, 235 patients (118 in the pre-ECS period and 117 in the ECS period) matched one of the inclusion criteria and were enrolled in the study. Compared with the pre-ECS period, the ECS period showed a reduction in the average consumption of packed red blood cells (−1.87 units, 95% confidence interval [CI], −2.40, −1.34), platelets (−1.28 units; 95% CI, −1.64, −0.91), and fresh frozen plasma (−1.69; 95% CI, −2.14, −1.25) in the first 24-hours. Furthermore, during the ECS period, we recorded a 10-day reduction in the hospital length of stay (−10 days, 95% CI, −11.6, −8.4) and a non-significant 28-day mortality increase. Conclusions: The ECS protocol was effective in reducing blood product consumption compared to the MTP and confirmed the importance of early fibrinogen administration as

OBJECTIVE: Hepatitis E Virus (HEV) is probably the most common cause of acute hepatitis worldwide. It has been regarded for a long time as a disease limited to developing countries. Recently, the refinement of diagnostic techniques, on the one hand, and migratory flows, on the other hand, have also led to the identification of an increased number of HEV infections in industrialized countries. Four HEV genotypes have been identified across the world, with different epidemiological burdens and a wide range of clinical presentations. Here, we report a case series of acute HEV hepatitis observed in the last three years in our hospital. PATIENTS AND METHODS: We performed a search for HEV IgM and IgG in all subjects admitted for acute hepatitis without evidence of other possible infectious, toxic or metabolic causes of liver damage. In subjects with HEV IgM positivity, the search for HEV-RNA was performed. RESULTS: We diagnosed eight acute HEV infections: 2 epidemic and 6 sporadic forms. HEV-RNA was detected in serum in 2 cases. CONCLUSIONS: HEV infection appears to be a cause of acute hepatitis that we must keep in mind even in developed countries.

The direct elucidation of the reaction pathways in heterogeneous catalysis has been challenging due to the short-lived nature of reaction intermediates. Here, we directly measured on ultrafast time scales the initial hydrogenation steps of adsorbed CO on a Ru catalyst surface, which is known as the bottleneck reaction in syngas and CO2 reforming processes. We initiated the hydrogenation of CO with an ultrafast laser temperature jump and probed transient changes in the electronic structure using real-time X-ray spectroscopy. In combination with theoretical simulations, we verified the formation of CHO during CO hydrogenation.

SCHEDA E.4 - La Legge del 2 dicembre 1994, n. 689 “Ratifica della Convenzione delle Nazioni Unite sul diritto del mare stipulata a Montego Bay, il 10 dicembre 1982” Con la Legge n. 689/1994 l’Italia ha ratificato La Convenzione delle Nazioni Unite sul Diritto del Mare, ad oggi firmata da 157 Stati e ratificata da 167. In un contesto storico mondiale in cui il mare oltre la fascia delle 3 miglia nautiche antistanti i litorali era considerato “acque internazionali”, ossia di proprietà di nessuno Stato e quindi di libero accesso, l’introduzione di questa Legge rappresenta una novità assoluta volta a creare ordine giuridico ed economico (con particolare riguardo ai Paesi in via di sviluppo anche privi di litorale1). Il Documento si basa sui principi di uso equo e pacifico delle risorse e della conservazione e protezione dell’ambiente marino in accordo con quanto espresso dalla Risoluzione n. 2749 (XXV) del 17 dicembre 1970, in cui l’Assemblea generale delle Nazioni Unite dichiarò solennemente, che «l’area del fondo marino e degli oceani ed il loro sottosuolo, oltre i limiti della giurisdizione nazionale, così come le sue risorse, sono da considerarsi patrimonio comune dell’umanità» (Introduzione al Compendio dei documenti base “The Law of the Sea”, 2001). L’UNCLOS è composto quindi da diverse Parti volte a disciplinare: - la definizione e regolamentazione degli spazi marini con l’introduzione dell’esercizio della Piattaforma Continentale, della Zona Economica Esclusiva (ZEE), della Zona di Protezione Ecologica (ZPE), della Zona Contigua, dell’alto mare e dell’“Area” relativa alle acque internazionali (PART II, PART IV - VIII, PART IX-XI); - la navigazione internazionale (PART III); - la conservazione e protezione dell’ambiente marino (cooperazione internazionale e regionale, monitoraggi e valutazione ambientale) (PART XII); - le ricerche scientifiche (PART XII); - lo sviluppo e il trasferimento di tecnologia marina. La necessità di adottare un regolamento interna

SCHEDA G.10 - Gli Accordi per la sicurezza offshore: Istituzioni, Enti di Ricerca e Università Ai sensi del Codice dell’Ambiente, come modificato dall’art. 35 del Decreto Legge n. 83/2012, l’aumento del 3% delle royalties per la produzione di olio e gas versate dagli operatori sono destinate ad apposito capi - tolo del Ministero dello sviluppo economico per assicurare il pieno svolgimento delle attività di vigilanza e controllo della sicurezza anche ambientale degli impianti di ricerca e coltivazione in mare. A questo scopo e per rispondere alle prescrizioni della Direttiva 2013/30/UE la DGS-UNMIG ha avviato nel 2014 collaborazioni con Forze Armate, Centri di Ricerca ed Università per il conseguimento di obiettivi finalizzati a: - definizione di un indicatore di sicurezza e sostenibilità - miglioramento del monitoraggio e innovazione tecnologica - definizione di regolamentazione e best practices - dialogo e trasparenza con gli stakeholders. Questi obiettivi di progetto si pongono a supporto delle attività istituzionali legate alla sicurezza mineraria ed energetica portate avanti dalla Direzione. Gli accordi hanno in primo luogo permesso alla DGS-UNMIG di usufruire di una rete di conoscenze specifiche multidisciplinari applicate al settore della sicurezza con il coinvolgimento di professori, ricercatori, assegnisti di ricerca sia presso gli enti che in distacco presso la Direzione al fine di cooperare giornalmente su questi temi. Attraverso il network, così come ad oggi è ribattezzato l’insieme delle partnership sulla sicurezza, la Direzione ha la possibilità di studiare e produrre nuove conoscenze relativamente a temi di frontiera, pervenendo a risultati tecnici e rigorosi trattati con metodo scientifico e sperimentale: attraverso la misurazione, l’analisi, l’elaborazione e quando necessario ripartendo da nuove assunzioni. I primi risultati significativi sono emersi nel 2015 nell’ambito dei monitoraggi. Dopo un anno di attività infatti la Marina Militare e

SCHEDA G.7 - Il sisma del 2012 e la Commissione per l’esplorazione di idrocarburi e la sismicità in Emilia Romagna (ICHESE) Il 20 e il 29 maggio 2012 due eventi sismici, rispettivamente di magnitudo locale 5.9 e 5.8, interessarono l’area dell’Emilia Romagna intorno ai comuni di Finale Emilia e Mirandola, causando diversi danni soprattutto nelle aree prossime agli epicentri. Considerata la vocazione mineraria della Regione Emilia Romanga e il numero di impianti di coltivazione di idrocarburi, di stoccaggio di gas naturale e di produzione geotermica, l’allora Presidente della Regione chiese alla Protezione Civile di intervenire per far luce attraverso una Commissione scientifica autorevole sulle possibili correlazioni tra gli eventi sismici e le attività condotte sul territorio. La Protezione Civile ritenne quindi utile istituire una Commissione Internazionale di esperti oggi conosciuta con il nome di Commissione ICHESE (International Commission on Hydrocarbon Exploration and Seismicity in the Emilia Region). La Commissione era costituita da 6 Membri: - Prof. Peter Styles - Presidente della Commissione e Professore di Geofisica applicata della Keele University - Prof. Paolo Gasparini - Segretario della Commissione e Professore Emerito di Geofisica all’Università di Napoli Federico II - Prof. Ernst Huenges - Capo della Sezione tecnologie di Reservoir al GFZ di Postdam - Prof. Paolo Scandone - Professore di Geologia Strutturale dell’Università di Pisa - Prof. Stanislaw Lasocki - Professore di Scienze della terra e capo del Dipartimento di Sismologia e fisica dell’interno della terra dell’Accademia delle Scienze di Varsavia - Ing. Franco Terlizzese - Direttore generale della Direzione generale delle Risorse Minerarie ed Energetiche (DGRME) del Ministero dello sviluppo economico italiano La DGS-UNMIG (allora DGRME), per il tramite del Direttore generale, partecipò intensamente ai lavori della Commissione e a febbraio del 2014 venne pubblicato il Rapporto degli studi

We show that coadsorbed oxygen atoms have a dramatic influence on the CO desorption dynamics from Ru(0001). In contrast to the precursor-mediated desorption mechanism on Ru(0001), the presence of surface oxygen modifies the electronic structure of Ru atoms such that CO desorption occurs predominantly via the direct pathway. This phenomenon is directly observed in an ultrafast pump-probe experiment using a soft x-ray free-electron laser to monitor the dynamic evolution of the valence electronic structure of the surface species. This is supported with the potential of mean force along the CO desorption path obtained from density-functional theory calculations. Charge density distribution and frozen-orbital analysis suggest that the oxygen-induced reduction of the Pauli repulsion, and consequent increase of the dative interaction between the CO 5 sigma and the charged Ru atom, is the electronic origin of the distinct desorption dynamics. Ab initio molecular dynamics simulations of CO desorption from Ru(0001) and oxygen-coadsorbed Ru(0001) provide further insights into the surface bond-breaking process., AuthorCount:25

Femtosecond x-ray laser pulses are used to probe the carbon monoxide (CO) oxidation reaction on ruthenium (Ru) initiated by an optical laser pulse. On a time scale of a few hundred femtoseconds, the optical laser pulse excites motions of CO and oxygen (O) on the surface, allowing the reactants to collide, and, with a transient close to a picosecond (ps), new electronic states appear in the OK-edge x-ray absorption spectrum. Density functional theory calculations indicate that these result from changes in the adsorption site and bond formation between CO and O with a distribution of OC-O bond lengths close to the transition state (TS). After 1 ps, 10% of the CO populate the TS region, which is consistent with predictions based on a quantum oscillator model., AuthorCount:30

The hydrodynamic equations for a long-bowl gas centrifuge can be simplified to obtain a one-dimensional differential equation for the variation of the non-dimensional axial velocity in the radial direction. In this study the solution of the one-dimensional differential equation was revisited and an approximate finite element solution of the differential equation was developed. The primary analytical solution was found to be consistent with the finite element solution, but the associated simplified solutions were found not always to be consistent with the finite element solution. Improved values for the originally published centrifuge flow function parameters are also presented

The hydrodynamic equations for a long-bowl gas centrifuge can be simplified to obtain a one-dimensional differential equation for the variation of the non-dimensional axial velocity in the radial direction. In this study the solution of the one-dimensional differential equation was revisited and an approximate finite element solution of the differential equation was developed. The primary analytical solution was found to be consistent with the finite element solution, but the associated simplified solutions were found not always to be consistent with the finite element solution. Improved values for the originally published centrifuge flow function parameters are also presented

We show that coadsorbed oxygen atoms have a dramatic influence on the CO desorption dynamics from Ru(0001). In contrast to the precursor-mediated desorption mechanism on Ru(0001), the presence of surface oxygen modifies the electronic structure of Ru atoms such that CO desorption occurs predominantly via the direct pathway. This phenomenon is directly observed in an ultrafast pump-probe experiment using a soft x-ray free-electron laser to monitor the dynamic evolution of the valence electronic structure of the surface species. This is supported with the potential of mean force along the CO desorption path obtained from density-functional theory calculations. Charge density distribution and frozen-orbital analysis suggest that the oxygen-induced reduction of the Pauli repulsion, and consequent increase of the dative interaction between the CO 5 sigma and the charged Ru atom, is the electronic origin of the distinct desorption dynamics. Ab initio molecular dynamics simulations of CO desorption from Ru(0001) and oxygen-coadsorbed Ru(0001) provide further insights into the surface bond-breaking process., US Department of Energy, Basic Energy Science; Swedish Research Council (VR); Department of Energy, Laboratory Directed Research and Development; VolkswagenStiftung; LCLS, Stanford University; Lawrence Berkeley National Laboratory (LBNL); University of Hamburg; Center for Free Electron Laser Science (CFEL)

The adsorption structure of the molecular switch azobenzene on Ag(111) is investigated by a combination of normal incidence x-ray standing waves and dispersion-corrected density functional theory. The inclusion of nonlocal collective substrate response (screening) in the dispersion correction improves the description of dense monolayers of azobenzene, which exhibit a substantial torsion of the molecule. Nevertheless, for a quantitative agreement with experiment explicit consideration of the effect of vibrational mode anharmonicity on the adsorption geometry is crucial. © 2013 American Physical Society.

The adsorption structure of the molecular switch azobenzene on Ag(111) is investigated by a combination of normal incidence x-ray standing waves and dispersion-corrected density functional theory. The inclusion of nonlocal collective substrate response (screening) in the dispersion correction improves the description of dense monolayers of azobenzene, which exhibit a substantial torsion of the molecule. Nevertheless, for a quantitative agreement with experiment explicit consideration of the effect of vibrational mode anharmonicity on the adsorption geometry is crucial. © 2013 American Physical Society.

This study was carried out in the frame of the ADS European project aimed to the development of Accelerator Driven System technology for nuclear waste transmutation. The scope is to verify the possibility to simulate a two phase HLM (Heavy Liquid Metal) bubbly flow using the commercial CFD code CFX4.4. The first stage consisted of an experimental campaign for the measurement of the phase velocities by means of the ultrasound Doppler velocimetry (UDV) and local volume fractions using resistive probes. The eutectic alloy PbBi is located inside a cylindrical container made of stainless steel which is provided with an electrical heater. The measurements reported here were carried out at a fluid temperature of 180°C. Nitrogen (N2) gas was injected into the stagnant liquid metal by means of a single orifice with an inner diameter of 0.5 mm. The orifice is located in the centre of the cross-sectional area of the fluid container. The gas flow rate chosen for these experiments was restricted to values below 1.2 cm3/s in order to guarantee a single bubble flow regime. The simulation of the experiment was performed using the two fluid Euler/Euler model of CFX-4.4. The implemented drag laws were tested and compared with other drag laws taken from literature. The influence of the "non-drag forces" like the turbulent dispersion force and the lift force was also tested. Finally an advanced interpolation method based on optimization techniques was adopted in order to get the best fitting of the simulated velocity curves with the experimental ones. The results shows in general a good qualitative agreement of the experiment and the calculations, but a much better agreement can be found using the drag law coefficients derived by the above mentioned optimization technique, especially in the cases where the mass flow rates and the bubble mean diameters are relatively small.

This study was carried out in the frame of the ADS European project aimed to the development of Accelerator Driven System technology for nuclear waste transmutation. The scope is to verify the possibility to simulate a two phase HLM (Heavy Liquid Metal) bubbly flow using the commercial CFD code CFX4.4. The first stage consisted of an experimental campaign for the measurement of the phase velocities by means of the ultrasound Doppler velocimetry (UDV) and local volume fractions using resistive probes. The eutectic alloy PbBi is located inside a cylindrical container made of stainless steel which is provided with an electrical heater. The measurements reported here were carried out at a fluid temperature of 180°C. Nitrogen (N2) gas was injected into the stagnant liquid metal by means of a single orifice with an inner diameter of 0.5 mm. The orifice is located in the centre of the cross-sectional area of the fluid container. The gas flow rate chosen for these experiments was restricted to values below 1.2 cm3/s in order to guarantee a single bubble flow regime. The simulation of the experiment was performed using the two fluid Euler/Euler model of CFX-4.4. The implemented drag laws were tested and compared with other drag laws taken from literature. The influence of the "non-drag forces" like the turbulent dispersion force and the lift force was also tested. Finally an advanced interpolation method based on optimization techniques was adopted in order to get the best fitting of the simulated velocity curves with the experimental ones. The results shows in general a good qualitative agreement of the experiment and the calculations, but a much better agreement can be found using the drag law coefficients derived by the above mentioned optimization technique, especially in the cases where the mass flow rates and the bubble mean diameters are relatively small.

This study was carried out in the frame of the ADS European project aimed to the development of Accelerator Driven System technology for nuclear waste transmutation. The scope is to verify the possibility to simulate a two phase HLM (Heavy Liquid Metal) bubbly flow using the commercial CFD code CFX4.4. The first stage consisted of an experimental campaign for the measurement of the phase velocities by means of the ultrasound Doppler velocimetry (UDV) and local volume fractions using resistive probes. The eutectic alloy PbBi is located inside a cylindrical container made of stainless steel which is provided with an electrical heater. The measurements reported here were carried out at a fluid temperature of 180°C. Nitrogen (N2) gas was injected into the stagnant liquid metal by means of a single orifice with an inner diameter of 0.5 mm. The orifice is located in the centre of the cross-sectional area of the fluid container. The gas flow rate chosen for these experiments was restricted to values below 1.2 cm3/s in order to guarantee a single bubble flow regime. The simulation of the experiment was performed using the two fluid Euler/Euler model of CFX-4.4. The implemented drag laws were tested and compared with other drag laws taken from literature. The influence of the "non-drag forces" like the turbulent dispersion force and the lift force was also tested. Finally an advanced interpolation method based on optimization techniques was adopted in order to get the best fitting of the simulated velocity curves with the experimental ones. The results shows in general a good qualitative agreement of the experiment and the calculations, but a much better agreement can be found using the drag law coefficients derived by the above mentioned optimization technique, especially in the cases where the mass flow rates and the bubble mean diameters are relatively small.

This study was carried out in the frame of the ADS European project aimed to the development of Accelerator Driven System technology for nuclear waste transmutation. The scope is to verify the possibility to simulate a two phase HLM (Heavy Liquid Metal) bubbly flow using the commercial CFD code CFX4.4. The first stage consisted of an experimental campaign for the measurement of the phase velocities by means of the ultrasound Doppler velocimetry (UDV) and local volume fractions using resistive probes. The eutectic alloy PbBi is located inside a cylindrical container made of stainless steel which is provided with an electrical heater. The measurements reported here were carried out at a fluid temperature of 180°C. Nitrogen (N2) gas was injected into the stagnant liquid metal by means of a single orifice with an inner diameter of 0.5 mm. The orifice is located in the centre of the cross-sectional area of the fluid container. The gas flow rate chosen for these experiments was restricted to values below 1.2 cm3/s in order to guarantee a single bubble flow regime. The simulation of the experiment was performed using the two fluid Euler/Euler model of CFX-4.4. The implemented drag laws were tested and compared with other drag laws taken from literature. The influence of the "non-drag forces" like the turbulent dispersion force and the lift force was also tested. Finally an advanced interpolation method based on optimization techniques was adopted in order to get the best fitting of the simulated velocity curves with the experimental ones. The results shows in general a good qualitative agreement of the experiment and the calculations, but a much better agreement can be found using the drag law coefficients derived by the above mentioned optimization technique, especially in the cases where the mass flow rates and the bubble mean diameters are relatively small.