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Computational fluid dynamics play a crucial role in the design of cooling systems in gas turbine combustors due to the difficulties and costs related to experimental measurements performed in pressurized reactive environments. Despite the massive advances in computational resources in the last years, reactive unsteady and multi-scale simulations of combustor real operating conditions are still computationally expensive. Modern combustors often employ cooling schemes based on effusion technique, which provides uniform protection of the liner from hot gases, combining the heat removal by means of heat sink effect with liner coverage and protection by film cooling. However, a large number of effusion holes results in a relevant increase of computational resources required to perform a CFD simulation capable of correctly predicting the thermal load on the metal walls within the combustor. Moreover, a multi-physics and multi-scale approach is mandatory to properly consider the different characteristic scales of the several heat transfer modes within combustion chambers to achieve a reliable prediction of aero-thermal fields within the combustor and wall heat fluxes and temperatures. From this point of view, loosely-coupled approaches permit a strong reduction of the calculation time, since each physics is solved through a dedicated solver optimized according to the considered heat transfer mechanism. The object of this work is to highlight the capabilities of a loosely-coupled unsteady multi-physics tool (U-THERM3D) developed at the University of Florence within ANSYS Fluent. The coupling strategy will be employed for the numerical analysis of the TECFLAM effusion cooled swirl burner, an academic test rig well representative of the working conditions of a partially premixed combustion chamber equipped with an effusion cooling system, developed by the collaboration of the Universities of Darmstadt, Heidelberg, Karlsruhe, and the DLR. The highly detailed numerical results obtained from the unsteady multi-physics and multi-scale simulation will be compared with experimental data to validate the numerical procedure.

One of the main challenges associated with the development of Rotating Detonation Combustion Engines (RDE) is dissipating the tremendous amount of heat generated by the high-frequency rotating detonation waves. The Current research aims to develop cooling designs for RDE.

The coefficient of variation (COV) of ozone residual is often used to compare the mixing performance of different ozone contacting systems. Multiphase mass transfer CFD modeling is performe...

Dried natural extracts demand challenges to the production process, especially when encapsulated in hard shells to avoid compromising the integrity of the capsule and extract. The present study describes a preliminary comparative approach on the changes in properties of hard gelatin and hypromellose capsules containing senna (Cassia angustifolia Vahl) leaf dry extract under two storage conditions. Therefore, loss on drying, disintegration, resistance to breakage, water activity, and microbial contamination after 6 mo at 30°/65% RH and 40°/75% RH were evaluated using Pharmacopoeia, AOAC and the manufacturer´s methods. The contents of sennoside A and sennoside B in the capsules were assessed by HPLC. Fine-tosuperfine powder of the extract presenting 0.14% total ash and 2.9% loss on drying was applied. Uniformity of mass was repeatable independently of gelatin and hypromellose shells (p > 0.05, t-test). The hypromellose capsules were more resistant to breakage than those of gelatin (maxima broken of 1/100 versus 42/100), in which the water content (2.9% to 5.7%) and water activity (0.33 to 0.43 aw) of the extract were intensively increased and, additionally, an acceptable increase in microbial contamination was observed. Compared to hypromellose shells, gelatin capsules did not maintain the same levels of both sennosides at 40°/75% RH, while sennoside B was lower. In conclusion, hypromellose performed better than gelatin to provide stable capsules, for resistance to breakage and disintegration unchanged, and offered higher protection to senna dry extract against humidity, microbial contamination and sennoside degradation. Overall, these preliminary results suggest the use of hypromellose encapsulation as a good alternative to gelatin in the production of medicinal capsules containing herbal dry extracts, mainly those with high hygroscopicity, and provide preliminary support for designing stability studies of capsules containing dry extracts that present high hygroscopicity.

All authors: Ortiz, J. L.; Santos-Sanz, P.; Sicardy, B.; Benedetti-Rossi, G.; Duffard, R.; Morales, N.; Braga-Ribas, F.; Fernández-Valenzuela, E.; Nascimbeni, V.; Nardiello, D.; Carbognani, A.; Buzzi, L.; Aletti, A.; Bacci, P.; Maestripieri, M.; Mazzei, L.; Mikuz, H.; Skvarc, J.; Ciabattari, F.; Lavalade, F. Scarfi, G.; Mari, J. M.; Conjat, M.; Sposetti, S.; Bachini, M.; Succi, G.; Mancini, F.; Alighieri, M.; Dal Canto, E.; Masucci, M.; Vara-Lubiano, M.; Gutiérrez, P. J.; Desmars, J.; Lecacheux, J.; Vieira-Martins, R.; Camargo, J. I. B.; Assafin, M.; Colas, F.; Beisker, W.; Behrend, R.; Mueller, T. G.; Meza, E.; Gomes-Junior, A. R.; Roques, F.; Vachier, F.; Mottola, S.; Hellmich, S.; Campo Bagatin, A.; Alvarez-Candal, A.; Cikota, S.; Cikota, A.; Christille, J. M.; Pál, A.; Kiss, C.; Pribulla, T.; Komžík, R.; Madiedo, J. M.; Charmandaris, V.; Alikakos, J.; Szakáts, R.; Farkas-Takács, A.; Varga-Verebélyi, E.; Marton, G.; Marciniak, A.; Bartczak, P.; Butkiewicz-Baķ, M.; Dudziński, G.; Alí-Lagoa, V.; Gazeas, K.; Paschalis, N.; Tsamis, V.; Guirado, J. C.; Peris, V.; Iglesias-Marzoa, R.; Schnabel, C.; Manzano, F.; Navarro, A.; Perelló, C.; Vecchione, A.; Noschese, A.; Morrone, L., Context. Deriving physical properties of trans-Neptunian objects is important for the understanding of our Solar System. This requires observational efforts and the development of techniques suitable for these studies. Aims. Our aim is to characterize the large trans-Neptunian object (TNO) 2002 TC302. Methods. Stellar occultations offer unique opportunities to determine key physical properties of TNOs. On 28 January 2018, 2002 TC302 occulted a mv ∼ 15.3 star with designation 593-005847 in the UCAC4 stellar catalog, corresponding to Gaia source 130957813463146112. Twelve positive occultation chords were obtained from Italy, France, Slovenia, and Switzerland. Also, four negative detections were obtained near the north and south limbs. This represents the best observed stellar occultation by a TNO other than Pluto in terms of the number of chords published thus far. From the 12 chords, an accurate elliptical fit to the instantaneous projection of the body can be obtained that is compatible with the near misses. Results. The resulting ellipse has major and minor axes of 543 ± 18 km and 460 ± 11 km, respectively, with a position angle of 3 ± 1 degrees for the minor axis. This information, combined with rotational light curves obtained with the 1.5 m telescope at Sierra Nevada Observatory and the 1.23 m telescope at Calar Alto observatory, allows us to derive possible three-dimensional shapes and density estimations for the body based on hydrostatic equilibrium assumptions. The effective diameter in equivalent area is around 84 km smaller than the radiometrically derived diameter using thermal data from Herschel and Spitzer Space Telescopes. This might indicate the existence of an unresolved satellite of up to ∼300 km in diameter, which is required to account for all the thermal flux, although the occultation and thermal diameters are compatible within their error bars given the considerable uncertainty of the thermal results. The existence of a potential satellite also appears to be consistent with other ground-based data presented here. From the effective occultation diameter combined with absolute magnitude measurements we derive a geometric albedo of 0.147 ± 0.005, which would be somewhat smaller if 2002 TC302 has a satellite. The best occultation light curves do not show any signs of ring features or any signatures of a global atmosphere. © ESO 2020., This research was partially based on data taken at the Sierra Nevada Observatory, which is operated by the Instituto de Astrofisica de Andalucia (CSIC). This research is also partially based on data taken at the German-Spanish Calar Alto observatory, which is jointly operated by the Max Planck Institute fur Astronomie and the Instituto de Astrofisica de Andalucia (CSIC). Part of the results were also based on observations taken at the 1.6m telescope on Pico dos Dias Observatory. This research was partially based on observations collected at the Schmidt telescope 67/92 cm (Asiago, Italy) of the INAF - Osservatorio Astronomico di Padova. Funding from Spanish projects AYA2014-56637-C2-1-P, AYA2017-89637-R, from FEDER, and Proyecto de Excelencia de la Junta de Andalucia 2012-FQM1776 is acknowledged. We would like to acknowledge financial support by the Spanish grant AYA-RTI2018-098657-JI00 "LEO-SBNAF" (MCIU/AEI/FEDER, UE) and the financial support from the State Agency for Research of the Spanish MCIU through the "Center of Excellence Severo Ochoa" award for the Instituto de Astrofisica de Andalucia (SEV- 2017-0709). Part of the research received funding from the European Union's Horizon 2020 Research and Innovation Programme, under grant agreement no. 687378 and from the ERC programme under Grant Agreement no. 669416 Lucky Star. The following authors acknowledge the respective CNPq grants: FB-R 309578/2017-5; RV-M 304544/2017-5, 401903/2016-8; J.I.B.C. 308150/2016-3; MA 427700/2018-3, 310683/2017-3, 473002/2013-2. This study was financed in part by the CoordenacAo de Aperfeiacoamento de Pessoal de Nivel Superior - Brasil (CAPES) - Finance Code 001 and the National Institute of Science and Technology of the e-Universe project (INCT do e-Universo, CNPq grant 465376/2014-2). GBR acknowledges CAPES-FAPERJ/PAPDRJ grant E26/203.173/2016, MA FAPERJ grant E-26/111.488/2013 and ARGJr FAPESP grant 2018/11239-8. E.F.-V. acknowledges support from the 2017 Preeminent Postdoctoral Program (P3) at UCF. C.K., R.S., A.F-T., and G.M. have been supported by the K-125015 and GINOP-2.3.2-15-2016-00003 grants of the Hungarian National Research, Development and Innovation Office (NKFIH), Hungary. G.M. was also supported by the Hungarian National Research, Development and Innovation Office (NKFIH) grant PD-128 360. R.K. and T.P. were supported by the VEGA 2/0031/18 grant. We acknowledge the use of Occult software by D. Herald.

Typical ozone mixing and mass transfer calculations are lumped approaches based on ideal operating conditions and can misrepresent behavior in real-life installations. This article models the effect of local hydrodynamics and mixing on the overall mass transfer of ozone into water with the aid of multiphase computational fluid dynamics (CFD). CFD models were validated with measured data from a pipeline ozone contactor installation which was optimized for more rapid, uniform mixing and mass transfer. Results emphasize the sensitivity of mixing quality to nozzle placement, size, orientation and spacing relative to main pipeline diameter and flows.

Modern lean burn aero-engine combustors make use of relevant swirl degrees for flame stabilization. Moreover important temperature distortions are generated, in tangential and radial directions, due to discrete fuel injection and liner cooling flows respectively. At the same time, more efficient devices are employed for liner cooling and a less intense mixing with the mainstream occurs. As a result, aggressive swirl fields, high turbulence intensities and strong hot streaks are achieved at the turbine inlet. In order to understand combustor-turbine flow field interactions, it is mandatory to collect reliable experimental data at representative flow conditions. While the separated effects of temperature, swirl and turbulence on the first turbine stage have been widely investigated, reduced experimental data is available when it comes to consider all these factors together. In this perspective, an annular three-sector combustor simulator with fully cooled high pressure vanes has been designed and installed at the THT Lab of University of Florence. The test rig is equipped with three axial swirlers, effusion cooled liners and six film cooled high pressure vanes passages, for a vortex-to-vane count ratio of 1:2. The relative clocking position between swirlers and vanes has been chosen in order to have the leading edge of the central NGV aligned with the central swirler. In order to generate representative conditions, a heated mainstream passes though the axial swirlers of the combustor simulator, while the effusion cooled liners are fed by air at ambient temperature. The resulting flow field exiting from the combustor simulator and approaching the cooled vane can be considered representative of a modern Lean Burn aero engine combustor with swirl angles above ±50°, turbulence intensities up to about 28% and maximum-to-minimum temperature ratio of about 1.25. With the final aim of investigating the hot streaks evolution through the cooled high pressure vane, the mean aerothermal field (temperature, pressure and velocity fields) has been evaluated by means of a five hole probe equipped with a thermocouple and traversed upstream and downstream of the NGV cascade.

Over the last years, aero-engines are progressively evolving toward design concepts that permit improvements in terms of engine safety, fuel economy, and pollutant emissions. With the aim of satisfying the strict NOx reduction targets imposed by ICAO-CAEP, lean burn technology is one of the most promising solutions even if it must face safety concerns and technical issues. Hence, a depth insight on lean burn combustion is required, and computational fluid dynamics can be a useful tool for this purpose. In this work, a comparison in large eddy simulation (LES) framework of two widely employed combustion approaches like the artificially thickened flame (ATF) and the flamelet generated manifold (FGM) is performed using ANSYS fluent v16.2. Two literature test cases with increasing complexity in terms of geometry, flow field, and operating conditions are considered. First, capabilities of FGM are evaluated on a single swirler burner operating at ambient pressure with a standard pressure atomizer for spray injection. Then, a second test case, operated at 4 bar, is simulated. Here, kerosene fuel is burned after an injection through a prefilming airblast atomizer within a corotating double swirler. Obtained comparisons with experimental results show different capabilities of ATF and FGM in modeling the partially premixed behavior of the flame and provide an overview of the main strengths and limitations of the modeling strategies under investigation.

Although the discovery of urease as the first enzyme for which nickel is essential for activity dates back to 1975, the rationale for Ni selection for the active site of this hydrolase has been only recently unraveled. The past 20 years have indeed witnessed impressive achievements in the understanding of the biological chemistry of Ni in urease, and in this chapter we aim to describe and discuss the recent advances in the comprehension of the specific role of this metal in the catalysis of urea hydrolysis. In particular, the structural features of the enzyme bound to several small molecules have shed light on the catalytic and inhibition mechanisms. The urease activation process, involving insertion of Ni into the urease active site through the action of the accessory proteins UreE, UreD, UreF, and UreG, is also dissected and analyzed.

Ortiz, José Luis et. al., Haumea-one of the four known trans-Neptunian dwarf planets- is a very elongated and rapidly rotating body1-3. In contrast to other dwarf planets4-6, its size, shape, albedo and density are not well constrained. The Centaur Chariklo was the first body other than a giant planet known to have a ring system7, and the Centaur Chiron was later found to possess something similar to Chariklo's rings8,9. Here we report observations from multiple Earth-based observatories of Haumea passing in front of a distant star (a multichord stellar occultation). Secondary events observed around the main body of Haumea are consistent with the presence of a ring with an opacity of 0.5, width of 70 kilometres and radius of about 2,287 kilometres. The ring is coplanar with both Haumea's equator and the orbit of its satellite Hi'iaka. The radius of the ring places it close to the 3:1 mean-motion resonance with Haumea's spin period-that is, Haumea rotates three times on its axis in the time that a ring particle completes one revolution. The occultation by the main body provides an instantaneous elliptical projected shape with axes of about 1,704 kilometres and 1,138 kilometres. Combined with rotational light curves, the occultation constrains the three-dimensional orientation of Haumea and its triaxial shape, which is inconsistent with a homogeneous body in hydrostatic equilibrium. Haumea's largest axis is at least 2,322 kilometres, larger than previously thought, implying an upper limit for its density of 1,885 kilograms per cubic metre and a geometric albedo of 0.51, both smaller than previous estimates1,10,11. In addition, this estimate of the density of Haumea is closer to that of Pluto than are previous estimates, in line with expectations. No global nitrogen- or methane-dominated atmosphere was detected.© 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved., J.L.O. acknowledges funding from Spanish and Andalusian grants MINECO AYA-2014-56637-C2-1-P and J. A. 2012-FQM1776 as well as FEDER funds. Part of the research leading to these results received funding from the European Union's Horizon 2020 Research and Innovation Programme, under grant agreement no. 687378. B.S. acknowledges support from the French grants 'Beyond Neptune' ANR-08-BLAN-0177 and 'Beyond Neptune II' ANR-11-1S56-0002. Part of the research leading to these results has received funding from the European Research Council under the European Community's H2020 (2014-2020/ERG grant agreement no. 669416 'Lucky Star'). A.P. and R.S. have been supported by the grant LP2012-31 of the Hungarian Academy of Sciences. All of the Hungarian contributors acknowledge the partial support from K-125015 grant of the National Research, Development and Innovation Office (NKFIH). G.B.-R., F.B.-R., F.L.R., R.V.-M., J.I.B.C., M.A., A.R.G.-J. and B.E.M. acknowledge support from CAPES, CNPq and FAPERJ. J.C.G. acknowledges funding from AYA2015-63939-C2-2-P and from the Generalitat Valenciana PROMETEOII/2014/057. K.H. and P.P. were supported by the project RVO:67985815. The Astronomical Observatory of the Autonomous Region of the Aosta Valley acknowledges a Shoemaker NEO Grant 2013 from The Planetary Society. We acknowledge funds from a 2016 'Research and Education' grant from Fondazione CRT. We also acknowledge the Slovakian project ITMS no. 26220120029.

Haumea-one of the four known trans-Neptunian dwarf planets- is a very elongated and rapidly rotating body1-3. In contrast to other dwarf planets4-6, its size, shape, albedo and density are not well constrained. The Centaur Chariklo was the first body other than a giant planet known to have a ring system7, and the Centaur Chiron was later found to possess something similar to Chariklo's rings8,9. Here we report observations from multiple Earth-based observatories of Haumea passing in front of a distant star (a multichord stellar occultation). Secondary events observed around the main body of Haumea are consistent with the presence of a ring with an opacity of 0.5, width of 70 kilometres and radius of about 2,287 kilometres. The ring is coplanar with both Haumea's equator and the orbit of its satellite Hi'iaka. The radius of the ring places it close to the 3:1 mean-motion resonance with Haumea's spin period-that is, Haumea rotates three times on its axis in the time that a ring particle completes one revolution. The occultation by the main body provides an instantaneous elliptical projected shape with axes of about 1,704 kilometres and 1,138 kilometres. Combined with rotational light curves, the occultation constrains the three-dimensional orientation of Haumea and its triaxial shape, which is inconsistent with a homogeneous body in hydrostatic equilibrium. Haumea's largest axis is at least 2,322 kilometres, larger than previously thought, implying an upper limit for its density of 1,885 kilograms per cubic metre and a geometric albedo of 0.51, both smaller than previous estimates1,10,11. In addition, this estimate of the density of Haumea is closer to that of Pluto than are previous estimates, in line with expectations. No global nitrogen- or methane-dominated atmosphere was detected. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.

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Increasing turbine inlet temperature is one of the main strategies used to accomplish the demands of increased performance of modern gas turbines. As a consequence, optimization of the cooling system is of paramount importance in gas turbine development. Leading edge represents a critical part of cooled nozzles and blades, given the presence of the hot gases stagnation point and the unfavourable geometry for cooling. This paper reports the results of a numerical investigation aimed at assessing the rotation effects on the heat transfer distribution in a realistic leading edge internal cooling system of a high pressure gas turbine blade. The numerical investigation was carried out in order to support and to allow an in-depth understanding of the results obtained in a parallel experimental campaign. The model is composed of a trapezoidal feeding channel which provides air to the cold bridge system by means of three large racetrack-shaped holes, generating coolant impingement on the internal concave leading edge surface, whereas four big fins assure the jets confinement. Air is then extracted through 4 rows of 6 holes reproducing the external cooling system composed of shower-head and film cooling holes. Experiments were performed in static and rotating conditions replicating the typical range of jet Reynolds number (Rej) from 10000 to 40000 and Rotation number (Roj) up to 0.05, for three crossflow cases representative of the working condition that can be found at blade tip, midspan and hub, respectively. Experimental results in terms of flow field measurements on several internal planes and heat transfer coefficient on the LE internal surface have been performed on two analogous experimental campaigns at University of Udine and University of Florence respectively. Hybrid RANS-LES models were used for the simulations, such as Scale Adaptive Simulation (SAS) and Detached Eddy Simulation (DES), given their ability to resolve the complex flow field associated with jet impingement. Numerical flow field results are reported in terms of both jet velocity profiles and 2D vector plots on symmetry and transversal internal planes, while the heat transfer coefficient distributions are presented as detailed 2D maps together with radial and tangential averaged Nusselt number profiles. A fairly good agreement with experimental measurements is observed, which represent a validation of the adopted computational model. As a consequence, the computed aerodynamic and thermal fields also allow an in-depth interpretation of the experimental results.

This research study investigates mixing and ozone mass transfer characteristics of a pilot-scale in-line multi-jets ozone contacting system. The hydrodynamic characteristics of the contactor were studied using a two-dimensional laser flow map particle image velocimetry coupled with planar laser induced fluorescence (PIV/PLIF). The PIV/PLIF system provided a combination of simultaneous whole-field velocity and concentration data in two-phase flows for different operating conditions. All measurements were conducted under a total liquid flow rate of about 10 L/s with gas flow rate ranging from 0.05 to 0.4 L/s. The gas was introduced to the system through a series of side stream injectors. The side injectors were tested under opposing and alternating modes. A mass transfer study was also conducted to estimate the overall mass transfer coefficient under the same operational conditions used for the hydrodynamics study. It was found that for the same number of jets (i.e., same gas flow rate) the liquid dispersio...

Turbine entry conditions are characterized by unsteady and strongly non-uniform velocity, temperature and pressure fields. The uncertainty and the lack of confidence associated with these conditions require the application of wide safety margins during the design of the turbine cooling systems, with a detrimental effect on engine efficiency. The adoption of lean-burn technology in modern aero-engines to reduce NOx emissions exacerbates the situation, as the absence of dilution holes keeps the strong swirl component generated by the burners up to the combustor outlet and prevents to control the pattern factor. Complexity and costs associated with the experimental investigation of combustor-turbine interaction, makes Computational Fluid Dynamics (CFD) paramount to understand the physical phenomena involved. Moreover, due to the well-known limitations of the Reynolds-Averaged Navier-Stokes (RANS) approach and the increase in computational resources, hybrid RANS-LES models, such as Scale Adaptive Simulation (SAS), are proving to be a viable approach to capture the main structures of the flow field. This paper reports the main findings of the numerical investigation on a test rig representative of a lean-burn, effusion cooled, annular combustor, developed in the context of the EU Project FACTOR (Full Aerothermal Combustor-Turbine interactiOns Research) with the aim of studying combustor-turbine interaction. Results obtained with RANS and unsteady SAS were critically compared to experimental data and analysed in order to better understand the flow physics within such a device, as well as to assess the improvements related to the use of hybrid models. The main discrepancies between RANS and SAS are highlighted in predicting the recirculating region, which has slight influence on the velocity field at the combustor outlet, but affects dramatically mixing and the resulting temperature distribution. Accuracy of the results achieved suggest a possible exploitation of SAS model with a view to the future inclusion of the nozzle guide vanes within the test rig.

The industralists and the Italian Administration have carried out common objectives throughout the last years for the decontamination of the industrial areas of Piombino. The accomplishment of the miultifunctional platfonn allows to treat and to decontaminate sites of national interest and has as it puts the valuation of the decontaminated areas, the rational management and the recovery of the remainders of iron and steel industry in a plant for the production of hydraulic concrete (CIC).Los empresarios y la Administración italiana han llevado a cabo, a lo largo de los últimos años, objetivos comunes para la descontaminación de las áreas industriales de Piombino. La realización de una plataforma multifuncional permite tratar y descontaminar sitios de interés nacional y tiene como meta la valoración de las áreas descontaminadas, la gestión racional y la recuperación de los residuos siderúrgicos en una planta de producción de conglomerados hidráulicos (CIC).

The aim of this work is to investigate a bidisperse gas-solid fluidized bed by a Computational Fluid Dynamics (CFD) approach based on the multi-fluid model and to identify the influence of numerical issues on the accuracy of the bed segregation predictions. The selected simulation approach is based on Eulerian unsteady equations of motion for each phase coupled with the granular kinetic theory. The effect of grid size and time step on axial segregation of two different binary solid mixtures is investigated. The analysis of the simulation results, which implement previous findings with new data, confirms that firm conclusions on the capacity of the CFD model to predict the segregation dynamics in fluidized beds can be drawn only after careful verification of numerical uncertainties at the operating conditions under investigation. The results clearly show that an important contribution to the mismatch of computed and experimental axial segregation is due to numerical errors, which in turn strongly depend on the particular operating condition under consideration. The relationship between the average absolute error and a global parameter, which takes into account both the operating conditions and the spatial and temporal resolutions, is shown.

Solids mixtures produced in different fields of chemical engineering may be separated in their components by means of several techniques. Separation processes based on fluidization technology result promising. This contribution reports recent advances in the study of binary solids mixtures segregation in fluidized bed. It regards segregation assessment in a tapered fluidized bed and segregation modelling by adopting CFD simulation. A lab scale tapered fluidized bed was operated with bidisperse mixtures of particles characterized by equal densities and different sizes. The attention was focused on solids distribution in the classification apparatus and on the effects of the operating conditions. Components of binary mixtures may be successfully separated. The simulation of the segregating fluidized mixtures was carried out by means of commercial computing code as FLUENT 6.3, implementing a multi-fluid model. The simulation results were focused on the dynamics of the binary mixtures in a cylindrical column. Results of the experimental investigation and of the simulations have been critically analysed.

A system for Rayleigh fading simulation is presented together with the results of some experiments and field trials carried out for the purpose of comparison of burst error correcting codes. The most notable features of the system are to be found in the proposed approach to Rayleigh fading simulation, realized on a PC in an easy and flexible form, which can be conveniently interfaced to external hardware devices for measurement and test purposes. In modeling the Rayleigh channel, the classic Gilbert's model was modified, maintaining on the one hand its simple structure but avoiding on the other hand some inherent drawbacks. >

Nocturnal oxygen desaturation during the sleep is very frequent in patients affected by chronic obstructive pulmonary disease (COPD). Hypoventilation, rather than sleeping apnea, is commonly considered as the most relevant factor in the onset of nocturnal oxygen desaturation. On this topic, the Authors have carried on a study on the nocturnal hypoxemia in 70 hospitalized COPD patients with a mean FEV1% of 40 +/- 21 and a mean PaO2 of 67.7 +/- 6.1. Anthropometric features (sex, age, body mass index) and functional respiratory parameters (FEV1, FEV1/VC, PaO2, PaCO2, SaO2, pH) were considered. Moreover all the patients were monitorized with transcutaneous pulse oxymetry, while breathing environmental air, in nighttime. Mean oxyhemoglobinic nocturnal saturation (SaO2 noct.%), minimum registered value of nocturnal SaO2 (min SaO2 noct.%) and the minutes of nighttime SaO2or = 90% andor = 85% (tSaO2or = 90% eor = 85%) were considered. Fiftyfour patients (77.15%) were nocturnal desaturating (NOD), whereas 16 (22.85%) were not desaturating (nNOD). A statistically significant difference was found between the two groups as to the values of FEV1 (p0.05), PaCO2, pH, SaO2 noct.%, minimum SaO2 noct.% and tSaO2or = 90% andor = 85% (p0.0001). A statistically significant correlation was found between tSaO290% and BMI (r = 0.44), PaCO2 (r = 0.48) and pH (r = -0.44), as well as between tSaO285% and PaCO2 (r = 0.57) and pH (r= -0.50), between SaO2 noct.% and BMI (r = -0.45), PaCO2 (r = -0,50), FEV1 (r = 0.44) and pH (r = 0.46) and finally between minimum SaO2 noct.% and PaCO2 (r = -0.47) was found. Eighty percent of the NOD patients had PaO275 mm Hg and PaCO244 mm Hg. All the patients with PaCO250 mm Hg were NOD. In conclusion, all COPD subjects with FEV149% and daytime PaO260 mm Hg, particularly when associated to elevated PaCO2 values and high BMI, should undergo a nocturnal pulse oxymetry in order to identify possible nocturnal desaturations. In these patients reduced FEV1, high BMI and/or elevated PaCO2 appear to be predictive indexes of nocturnal desaturation. A PaCO250 mm Hg is highly indicative for a nocturnal oxygen desaturation.

The Authors discuss a case of amiodarone pulmonary toxicity, with simultaneous alveolar and interstitial infiltrates, in a female patient 75 years old, who took the drug for 6 months at a low dosage (200 mg/daily for 5 days a week). It is outlined that the diagnosis can be achieved only by exclusion of other aetiologies, since clinical and diagnostic features are not pathognomonic for such disease. The withdrawal of the drug and the administration of the steroid therapy determined a fast improvement of the clinical and radiological appearance.

Tuberculosis is heavily worldwide spreading in the last years. More and more signalations seem to indicate that the incidence of drug-resistant Mycobacteria is increasing in almost all industrialized countries. The authors have carried on a study on the percentage of drug-resistant strains of Mycobacterium Tuberculosis (MT) among isolates from patients affected by active pulmonary tuberculosis hospitalized through the years 1992-94. Out of 59 isolates of MT, 20.3% were drug-resistant: 25% of them to 2 drugs and 16.6% to 3 or more drugs. Resistance to single drug was so distributed: Streptomycin 11.8%, Isoniazid 6.7%, Rifampycin 3.4%, Ethambutol 6.7%, Ansamycin 3.4%, Pyrazinamide 5.0%, Ethionamide 1.7%. These results were confronted with analogous data on MT drug-resistance collected in the same hospital division in the years 1978-82 and 1985-87. The data analysis shows that actual incidence of drug resistant strains of MT is only slightly decreased but quite similar to that observed in 1978-82, except for Ethambutol, while there is a remarkable reduction vs. 1985-87; in that period, in fact, the highest incidence of drug resistance was recorded. The authors' conclusion is that only little differences were observed in the total amount of resistant strains of MT through 20 years; they also outline that resistance to Ansamycin, most recent out of all tested drugs, is quite similar to that observed for Rifampycin, that is chemically analogous.

The authors present 110 cases of patients hospitalized in the last 5 years, with long-term disabling sequelae of pulmonary tuberculosis. Twelve out of them (= 10.9%) suffered from post-tuberculous chronic empyema, with an average latency period of 44.83 years between the acute tuberculous illness and the clinical manifestation of the empyema. Nine of the patients had been treated with collapsotherapy, induced by artificial intrapleural pneumothorax, 1 with thoracoplasty, and 2 only with late and inadequate anti-mycobacterial chemotherapy. Eleven patients (91.6%) also had a cutaneous fistula (7 cases) and/or a bronchopleural fistula (4 cases). The authors show how the issue of tuberculous sequelae is a significant not only from the numerical standpoint, but also for the seriousness of the caused pathological conditions, often posing problems for differential diagnosis. Moreover, they stress how tuberculosis should never be neglected or considered last in the differential diagnosis of empyema and pyopneumothorax.

The XbaI Restriction Fragment Length Polymorphism (RFLP) of the APOB gene at codon 2488 was investigated in a sample group from Southern Italy (165 subjects), taken from a population characterized by a low average level of cholesterolemia. The X2 allele (presence of XbaI cutting site), that in several groups was found to be associated with increased cholesterolemia, showed in Southern Italians a frequency of 39% which is significantly (P much less than 0.001) lower than that found in the majority of the Caucasoid groups so far tested (50%). However, an analysis of both cholesterol and APOB serum levels performed in a sample of 82 subjects, homogeneous for sex and age did not reveal any significant association between lipidemic parameters and APOB-XbaI genotypes.

A solid jet is by definition a jet which upon impingement exhibits a line of stagnation points. The understanding of the impingement features is important for VTOL research (ejectors, helicopter rotors, and jet engines). The solution of this problem for the incompressible case was attained in 1962 by Strand1'2 by means of a conformal mapping technique which cannot be extended to the compressible regime. Our procedure, an extension of previously published work,3 starts from the equation of motion written in terms of the odograph independent variables; V, modulus of the velocity vector V\ and 0, angle between F and a reference axis. In this formulation the equations are linear and the solution can be represented as a sum of products of functions of Kand 6 only. We easily find that the functions of 6 are sinusoidal functions of a suitable argument both in the incompressible and compressible cases. The functions of V are very simple in the incompressible case, but in the compressible regime they have an expression in terms of hypergeometri c functions. We will numerically calculate each of them more easily by solving a difference system of algebraic equations originated by our differential equation. We study the fluid-dynamic field of the two-dimensional solid jet in proximity to the ground by assuming1 the angle 0 of the velocity with the x axis vanishing at x = 0 (Fig. 1). The equation that determines the compressible stream function [\l/y = p+u, \l/x = -pv, where u and v are the velocity components in a Cartesian system of coordinates (x9y)] written in terms of V and 0 is

An experiment has been performed to test the relevance of training in a Piagetian mini‐laboratory on the acquisition of two formal schemata: proportion and control of variables. The results obtained indicate that an improvement in the mastery of these forms of reasoning had been obtained by a sample 9th grade students (approximately 14 years of age). No such effect was detectable in the combinatorial formal schemata for which no training was provided.

In this work, we use a multifluid model to investigate numerically the dynamics of segregating fluidized bidisperse mixtures. The model uses the default multifluid equations of commercial computational fluid dynamics (CFD) codes, except for the fluid-particle drag force closure, which Mazzei and Lettieri [1] recently developed and extended to polydisperse systems. The study also comprises some preliminary simulations of collapsing monodisperse beds, focusing on the role of the plastic solid stress. This work tests whether the model is able to correctly predict not only the axial segregation profiles through the bed, but also the minimum fluid velocities at which a) the mixture, being no longer fixed, starts segregating and transient fluidization takes place, and b) the mixture becomes steadily fluidized and fully mixed. To validate the model predictions, we use the experimental findings of Marzocchella et al. [2]. The plastic stress results to play an important role, rendering the simulations more stable and allowing for larger time steps. The model well predicts the stationary axial segregation profiles, and for short computational times estimates correctly the onset of transient fluidization; for longer computational times, however, the system evolves towards a new steady state where, even if the powder is at maximum packing, it partly segregates. The model overestimates the velocity required to fully mix the suspension, probably because the simulated bubbling is not as vigorous as it is experimentally. (C) 2009 Elsevier B. V. All rights reserved.

Esame analitico della politica dei generi nella prima produzione cinematografica italiana. Il tema è affrontato sia dal punto di vista delle politiche industriali di marketing, sia dal punto di vista dell'uso delle etichette di genere da parte della critica coeva, sia infine dal punto di vista delle convenzioni stilistiche e figurative.

In this work we simulated the dynamics of a fluidized bed of a binary solid mixture using the isothermal multi-fluid model of the commercial CFD code Fluent 12. We focused the attention on the role of both restitution coefficient and integration methods on the dynamics of the bed, adopting a mixture of solids assorted in size (with constant density) as case study. We employed two methods of spatial discretization: first-order upwind scheme (FUS) and second-order upwind scheme (SUS). We investigated implicit versus explicit time integration methods as well. The numerical diffusion introduced by the FUS resulted in a low bubble fraction in the bed, in turn reducing solid mixing rates. Simulations carried out adopting the SUS were characterized by a reasonable bubble fraction and associated solid mixing rate. The latter method successfully predicted the transition to fully mixed, uniform fluidization conditions. The value of the restitution coefficient did not significantly affect the results of the simulations, as bubble volume fraction and jetsam concentration profiles did not show any significant change within the interval of restitution coefficient values investigated, with the exception of the nearly ideal value of 0.99. �� 2013 Elsevier Ltd.