Prediction of two-phase choked-flow through safety valves

Different models of two-phase choked flow through safety valves are applied in order to evaluate their capabilities of prediction in different thermal-hydraulic conditions. Experimental data available in the literature for two-phase fluid and subcooled liquid upstream the safety valve have been compared with the models predictions. Both flashing flows and non- flashing flows of liquid and incondensable gases have been considered. The present paper shows that for flashing flows good predictions are obtained by using the two-phase valve discharge coefficient defined by Lenzing and multiplying it by the critical flow rate in an ideal nozzle evaluated by either Omega Method or the Homogeneous Non-equilibrium Direct Integration. In case of non-flashing flows of water and air, Leung/Darby formulation of the two-phase valve discharge coefficient together with the Omega Method is more suitable to the prediction of flow rate

Experimental Study on the Flow Patterns and Two-phase Pressure Drops in a Horizontal Impacting T- Junction

The present paper analyzes the experimental results concerning the flow patterns and pressure drops in two-phase flow through an horizontal impacting T-junction, whose outlet pipes are aligned and perpendicular to the inlet pipe. The test section consists of plexiglass pipes with inner diameter of 10 mm. A mixture of water and air at ambient temperature and pressures up to 2.4 bar flows through the T-junction, with different splitting of flow rates in the two outlet branches; superficial velocities of air and water in the inlet pipe are varied up to a maximum of 35 m/s and 3.5 m/s respectively. The flow patterns occurring in the inlet and branch pipes were compared with the predictions of Baker’s and Taitel – Dukler’s maps. The pressure drops along the branches have been measured relatively to different splitting of the flow rate through the two branches and the pressure loss coefficients in the junction have been evaluated. Friction pressure drops have allowed us to evaluate two-phase friction multipliers, which have then been compared to the predictions of Lockhart-Martinelli, and Friedel correlations. Local pressure drops were extrapolated at the junction centre and analyzed; the two-phase multiplier has been evaluated and compared with the predictions of Chisholm correlation; the value of the empirical coefficient that minimizes the discrepancies has also been evaluated

Seasonal egg output of gastro-intestinal parasites in wild ungulates in a mediterranean area (central Italy)

Emissione stagionale di uova di parassiti gastrointestinali in cinghiali (Sus scrofa) e in mufloni (Ovis ammon) di un’area mediterranea (Italia centrale). E' stata studiata l'emissione stagionale di uova (o oocisti) di parassiti nelle feci di ungulati selvatici in una zona mediterranea protetta, il Parco dei Monti Livornesi (Livorno, Toscana, Italia Centrale). Per un anno sono stati raccolti mensilmente campioni di feci di Cinghiale (Sus scrofa) e di Muflone (Ovis ammon). Gli andamenti osservati di emissione di uova sono stati analizzati tenendo conto delle variazioni di temperatura e piovosità stagionali, del ciclo biologico e della strategia di sopravvivenza dei parassiti, e delle condizioni sanitarie dell'ospite. E’ risultato che in una zona mediterranea come quella considerata i picchi di emissione di uova appaiono in mesi differenti in relazione alla biologia e alle strategie di sopravvivenza dei diversi parassiti.Seasonal egg (or oocyst) output of gastro-intestinal parasites of wild ungulates was studied in a Mediterranean protected area, the Monti Livornesi Park (Livorno, Tuscany region, Central Italy). Samples of faeces of wild boars (Sus scrofa) and mouflons (Ovis ammon) were collected monthly for one year. The observed trends of egg output were analysed taking into account seasonal variations of temperature and rainfall, life-cycle and survival strategy of parasites, and health condition of hosts. In our Mediterranean study area, the peaks of egg output appear in different months according to different biology and survival strategies of parasites

Ingress of Coolant Event simulation with TRACE code with accuracy evaluation and coupled DAKOTA Uncertainty Analysis

Among the Postulated Initiating Events in nuclear fusion plants, the Ingress of Coolant Event (ICE) in the Plasma Chamber is one of the main safety issues. In the present paper, the best estimate thermal-hydraulic system code TRACE, developed by USNRC, has been adopted to study the ICE, and it has been qualified based on experimental results obtained in the Integrated ICE facility at JAERI. A nodalization has been developed in the SNAP environment/architecture, using also the TRACE 3D Vessel component where multidimensional phenomena could occur. The accuracy of the code calculation has been assessed both from a qualitative and quantitative point of view. In addition, an Uncertainty Analysis (UA), with the probabilistic method to propagate the input uncertainties, has been performed to characterize the dispersion of the results. The analysis has been carried out with the DAKOTA toolkit coupled with TRACE code in the SNAP environment/architecture. Results show the adequacy of the 3D nodalization and the capability of the code to follow the transient evolution also at a very low pressure. Response correlations have been computed to characterize the correlation between the selected uncertain input parameters and the Plasma Chamber pressure

Retroperitoneal pararenal isolated neurofibroma: report of a case and review of literature

The neurofibroma is a tumour of neural origin. This kind of neoplasm, though, is generally skin located. Rare cases in deep organs or in the peritoneal cavity are also reported in the literature. There are two types of neurofibromas, localized and diffuse; the latter is associated with von Recklinghausen disease and always occurs together with skin neurofibromas. Here we report the case of a 47-year-old man affected by retroperitoneal neurofibroma, but not associated with von Recklinghausen disease. A computed tomography (CT) scan described a retroperitoneal pararenal lesion with no clear involvement of adjacent viscera. We describe the diagnostic modality, treatment planning and the timing of treatment of this neoplasm, reviewing also the literature

Diatom extraction: A new technique with heated H2O2. A technical note

The best method of diatom identification in animal and human tissues is still an important discussion topic, in terms of effectiveness and reliability. In this technical note, authors propose a new method of extraction of diatoms using heated hydrogen peroxide from animal and human tissue samples. This method has been compared with the traditional method of digestion with acids. The results of the comparison show that heated hydrogen peroxide extraction is more efficient in terms of reduction of sediment, extraction of the material and preservation of diatoms proving to be a viable alternative to conventional approaches with acids in terms of costs and operator safety

Thermal hydraulic analysis of Alfred bayonet tube steam generator

The paper analyzes the performance of ALFRED steam generator from the thermal-hydraulic point of view highlighting the effect of some design features. The parameters object of the study are the regenerative heat transfer, the dimension of the inner tube and the length of the bayonet. The system code RELAP5-3D/2.4.2 has been chosen for the analysis. Sensitivities analysis allowed the determination of the different design parameters influence, here briefly summarized. The increase of regenerative heat transfer affects the efficiency of the steam generator through a degradation of the outlet steam quality: the number of bayonet tubes required to remove the nominal power increases with the increase of the global heat transfer coefficient of the inner tube. A higher inner diameter results in a larger surface area for the regenerative heat transfer and in a higher heat transfer coefficient in the annular region because of the reduction of the cross section. The result is an improvement of the performances of the steam generator thanks to the dimension reduction of the annular gap. Finally, if the height of the bayonet tube is reduced by 1 meter, the number of bayonet tubes required to remove the nominal power increases up to 20%

Negative serology of Fasciola hepatica infection in patients with liver cancer in Peru: A preliminary report

Introduction: The etiology of several hepatocellular carcinoma (HCC) cases remains largely unknown. Although Fasciola hepatica has been associated with liver fibrosis in Latin America, it has not yet been associated with HCC. This study aimed to determine the existence of specific IgG antibodies against F. hepatica in the serum samples of HCC patients. Methods: In total, 13 serum samples from 13 HCC patients were screened using Fas2-ELISA. Results: Fas2-ELISA demonstrated negative results in all HCC patients included in this study. Conclusions: The pre-existence of F. hepatica infection in HCC patients needs to be further investigated in epidemiological and experimental studies

CDKL5 expression is modulated during neuronal development and its subcellular distribution is tightly regulated by the C-terminal tail

Mutations in the human X-linked cyclin-dependent kinase-like 5 (CDKL5) gene have been identified in patients with Rett syndrome (RTT), West syndrome, and X-linked infantile spasms, sharing the common feature of mental retardation and early seizures. CDKL5 is a rather uncharacterized kinase, but its involvement in RTT seems to be explained by the fact that it works upstream of MeCP2, the main cause of Rett syndrome. To understand the role of this kinase for nervous system functions and to address if molecular mechanisms are involved in regulating its distribution and activity, we studied the ontogeny of CDKL5 expression in developing mouse brains by immunostaining and Western blotting. The expression profile of CDKL5 was compared with that of MeCP2. The two proteins share a general expression profile in the adult mouse brain, but CDKL5 levels appear to be highly modulated at the regional level. Its expression is strongly induced in early postnatal stages, and in the adult brain CDKL5 is present in mature neurons, but not in astroglia. Interestingly, the presence of CDKL5 in the cell nucleus varies at the regional level of the adult brain and is developmentally regulated. CDKL5 shuttles between the cytoplasm and the nucleus and the C-terminal tail is involved in localizing the protein to the cytoplasm in a mechanism depending on active nuclear export. Accordingly, Rett derivatives containing disease-causing truncations of the C terminus are constitutively nuclear, suggesting that they might act as gain of function mutations in this cellular compartment

Two-phase flow in a horizontal t-junction : pressure drop and phase separation

Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.An experimental investigation of dividing flow rates and pressure drops in a plexiglas tee junction with horizontal inlet, run, and branch sides using air-water mixtures has been performed. The branch stream is orthogonal to the inlet and run streams. The pipes forming the tee junction are about 1 m long, their inner diameter is 10 mm. The flow loop was supplied with compressed air and water through a mixing tee, at 1.5 bar and approximately ambient temperature. Air flow rate ranges from 0.3 to 9 Nl/s, water flow rate from 14.5 to 58 g/s, air superficial velocity from 1.5 to 47 m/s, water superficial velocity from 0.2 to 0.7 m/s and flow quality from 0.6% to 43%. The extraction ratio (branch flow rate / inlet flow rate) ranges from 0 to 1. Intermittent (bubble and slug flow) and annular flow patterns, as well as transition flow patterns have been obtained. Experimental values of flow rate, phases superficial velocity, extraction ratio and pressure drops across the tee junction pipes are here reported. Pressure drop test results across the inlet and branch pipes have also been compared with predicted ones. A new pressure drop correlation have been derived from test data.cs201