Nuovo Cimento Della Societa Italiana Di Fisica A-nuclei Particles and Fields, 2017
DarkSide is a dark matter direct search experiment at Laboratori Nazionali del Gran Sasso (LNGS).... more DarkSide is a dark matter direct search experiment at Laboratori Nazionali del Gran Sasso (LNGS). DarkSide is based on the detection of rare nuclear recoils possibly induced by hypothetical dark matter particles, which are supposed to be neutral, massive (m > 10 GeV) and weakly interactive (WIMP). The dark matter detector is a two-phase time projection chamber (TPC) filled with ultra-pure liquid argon. The TPC is placed inside a muon and a neutron active vetoes to suppress the background. Using argon as active target has many advantages, the key features are the strong discriminant power between nuclear and electron recoils, the spatial reconstruction and easy scalability to multi-tons size. At the moment DarkSide-50 is filled with ultra-pure argon, extracted from underground sources, and from April 2015 it is taking data in its final configuration. When combined with the preceding search with an atmospheric argon target, it is possible to set a 90% CL upper limit on the WIMP-nuc...
Proportional electroluminescence (EL) in noble gases is used in two-phase detectors for dark matt... more Proportional electroluminescence (EL) in noble gases is used in two-phase detectors for dark matter searches to record (in the gas phase) the ionization signal induced by particle scattering in the liquid phase. The “standard” EL mechanism is considered to be due to noble gas excimer emission in the vacuum ultraviolet (VUV). In addition, there are two alternative mechanisms, producing light in the visible and near infrared (NIR) ranges. The first is due to bremsstrahlung of electrons scattered on neutral atoms (“neutral bremsstrahlung”, NBrS). The second, responsible for electron avalanche scintillation in the NIR at higher electric fields, is due to transitions between excited atomic states. In this work, we have for the first time demonstrated two alternative techniques of the optical readout of two-phase argon detectors, in the visible and NIR range, using a silicon photomultiplier matrix and electroluminescence due to either neutral bremsstrahlung or avalanche scintillation. The...
The deformability of red blood cells flowing in microvessels is essential to maintain optimal blo... more The deformability of red blood cells flowing in microvessels is essential to maintain optimal blood circulation and to allow gas transfer between blood and tissues. Here, we report on an experimental methodology to investigate the deformability of RBCs flowing in microcapillaries having diameter close to the average cell size. The microcapillaries are placed in a rectangular flow cell, where a suspension of RBCs, properly diluted in albumin-additioned ACD, is fed through a syringe under the action of a liquid head in the physiological range. Video microscopy images of the flowing RBCs are acquired at high magnification and later processed by an automated image analysis macro. It was found that RBCs from healthy donors exhibit the classical parachute shape observed in vivo. Furthermore, all the data of healthy RBC velocity vs liquid head are well represented by the same linear regression, independently on the donor. Preliminary results on beta-thalassemia RBCs are also presented and ...
ABSTRACT The flow-induced morphology of aqueous mixtures of gelatin and dextran was investigated ... more ABSTRACT The flow-induced morphology of aqueous mixtures of gelatin and dextran was investigated during gelation of the dispersed phase. Mixtures with 5% volume fraction of the gelatin-rich phase dispersed in the dextran-rich phase were sheared in a translating parallel plate apparatus coupled with an optical microscope. Gelation of the dispersed phase was brought about by decreasing mixture temperature under flow. As a consequence of gelation, the dispersed phase aggregated, forming clusters of gelled, partially coalesced, spherical particles. Cluster size was found to depend on the shear rate applied during gelation and on the temperature profile. Indeed, smaller clusters were formed: (a) under faster flows, (b) if the temperature was decreased to lower levels, and (c) if gelation was induced under quiescent conditions and the flow started only afterwards. By acting on these parameters, it is possible to suppress or enhance cluster formation and to tune cluster size. When the temperature was increased again above the gelation temperature, the gelled particles melted and the clusters rapidly coalesced. (C) 2002 The Society of Rheology.
Drop deformation in equiviscous polymer blends with dispersed phase volume fraction ranging from ... more Drop deformation in equiviscous polymer blends with dispersed phase volume fraction ranging from 0 to 10% has been investigated by video microscopy and image analysis in a parallel plate shear apparatus. Under steady external flow conditions the shape of individual drops, as measured by the three main axes, the orientation angle and the deformation parameter, showed marked time fluctuations around an average value depending on dispersed phase concentration and on drop capillary number. At small volume fractions the deformed shape was essentially coincident with the isolated drop case, whereas the higher the concentration, the larger the observed drop deformation at a given capillary number. Such deviations from the isolated drop case can be attributed to hydrodynamic interactions, mainly due to flow-induced collisions among drops. The experimental results can be conveniently described by a mean field approximation whereby the forces causing drop deformation are taken as proportional...
Industrial & Engineering Chemistry Research, 2002
We study transient drop deformation in dilute emulsions for large values of the capillary number ... more We study transient drop deformation in dilute emulsions for large values of the capillary number Ca. We consider steady planar linear flows characterized by the dimensionless vorticity ‚. For drop-to-matrix viscosity ratios Ï < 1, we find that the drops are strongly elongated by the extensional component of the flow and widen along the vorticity direction because of the compressional
This work is focused on the investigation of coalescence under shear flow in aqueous mixtures of ... more This work is focused on the investigation of coalescence under shear flow in aqueous mixtures of Na-alginate and Na-caseinate. Shear flow was generated in a parallel plate apparatus coupled with an optical microscope. Drop size distribution was measured as a function of time by computer controlled 3D optical sectioning of the sample and offline image analysis. Automated procedures of image
Aria is a plant hosting a$${350}\,\hbox {m}$$350mcryogenic isotopic distillation column, the tall... more Aria is a plant hosting a$${350}\,\hbox {m}$$350mcryogenic isotopic distillation column, the tallest ever built, which is being installed in a mine shaft at Carbosulcis S.p.A., Nuraxi-Figus (SU), Italy. Aria is one of the pillars of the argon dark-matter search experimental program, lead by the Global Argon Dark Matter Collaboration. It was designed to reduce the isotopic abundance of$${^{39}\hbox {Ar}}$$39Arin argon extracted from underground sources, called Underground Argon (UAr), which is used for dark-matter searches. Indeed,$${^{39}\hbox {Ar}}$$39Aris a$$\beta $$β-emitter of cosmogenic origin, whose activity poses background and pile-up concerns in the detectors. In this paper, we discuss the requirements, design, construction, tests, and projected performance of the plant for the isotopic cryogenic distillation of argon. We also present the successful results of the isotopic cryogenic distillation of nitrogen with a prototype plant.
The deformation of an isolated drop immersed in an immiscible liquid phase undergoing shear flow ... more The deformation of an isolated drop immersed in an immiscible liquid phase undergoing shear flow has been the subject of a number of studies, both theoretical and experimental, as reviewed by Rallison (1984) and by Stone (1994). The dynamics of an isolated sheared drop can be regarded as a sort of elementary event, which can provide some insight into the complex rheological behavior of a flowing dispersion of drops, such as the one encountered in emulsions, polymer blends and food industry.
... S. Guido Corresponding Author Contact Information , E-mail The Corresponding Author , a , M. ... more ... S. Guido Corresponding Author Contact Information , E-mail The Corresponding Author , a , M. Simeone a and F. Greco b. ... The slope of the fitting line (within experimental error) is equal to 2, in agreement with the assumption of second-order fluids made in the theoretical analysis ...
ABSTRACT This paper presents a simulative analysis of the energy efficiency of solar aided biomas... more ABSTRACT This paper presents a simulative analysis of the energy efficiency of solar aided biomass gasification for pure hydrogen production. Solar heat has been considered as available at 250 °C in three gasification processes: i) gasification reactor followed by two water gas shift reactors and a pressure swing adsorber; ii) gasification reactor followed by an integrated membrane water gas shift reactor; iii) supercritical gasification reactor followed by two flash separators and a pressure swing adsorber. Simulations are performed with the commercial software Aspen Plus® by considering biomass moisture content and the amount of solar heat as system variables. Results are presented in terms of energy and exergy system efficiency and are discussed and compared with the case of no solar integration.
Nuovo Cimento Della Societa Italiana Di Fisica A-nuclei Particles and Fields, 2017
DarkSide is a dark matter direct search experiment at Laboratori Nazionali del Gran Sasso (LNGS).... more DarkSide is a dark matter direct search experiment at Laboratori Nazionali del Gran Sasso (LNGS). DarkSide is based on the detection of rare nuclear recoils possibly induced by hypothetical dark matter particles, which are supposed to be neutral, massive (m > 10 GeV) and weakly interactive (WIMP). The dark matter detector is a two-phase time projection chamber (TPC) filled with ultra-pure liquid argon. The TPC is placed inside a muon and a neutron active vetoes to suppress the background. Using argon as active target has many advantages, the key features are the strong discriminant power between nuclear and electron recoils, the spatial reconstruction and easy scalability to multi-tons size. At the moment DarkSide-50 is filled with ultra-pure argon, extracted from underground sources, and from April 2015 it is taking data in its final configuration. When combined with the preceding search with an atmospheric argon target, it is possible to set a 90% CL upper limit on the WIMP-nuc...
Proportional electroluminescence (EL) in noble gases is used in two-phase detectors for dark matt... more Proportional electroluminescence (EL) in noble gases is used in two-phase detectors for dark matter searches to record (in the gas phase) the ionization signal induced by particle scattering in the liquid phase. The “standard” EL mechanism is considered to be due to noble gas excimer emission in the vacuum ultraviolet (VUV). In addition, there are two alternative mechanisms, producing light in the visible and near infrared (NIR) ranges. The first is due to bremsstrahlung of electrons scattered on neutral atoms (“neutral bremsstrahlung”, NBrS). The second, responsible for electron avalanche scintillation in the NIR at higher electric fields, is due to transitions between excited atomic states. In this work, we have for the first time demonstrated two alternative techniques of the optical readout of two-phase argon detectors, in the visible and NIR range, using a silicon photomultiplier matrix and electroluminescence due to either neutral bremsstrahlung or avalanche scintillation. The...
The deformability of red blood cells flowing in microvessels is essential to maintain optimal blo... more The deformability of red blood cells flowing in microvessels is essential to maintain optimal blood circulation and to allow gas transfer between blood and tissues. Here, we report on an experimental methodology to investigate the deformability of RBCs flowing in microcapillaries having diameter close to the average cell size. The microcapillaries are placed in a rectangular flow cell, where a suspension of RBCs, properly diluted in albumin-additioned ACD, is fed through a syringe under the action of a liquid head in the physiological range. Video microscopy images of the flowing RBCs are acquired at high magnification and later processed by an automated image analysis macro. It was found that RBCs from healthy donors exhibit the classical parachute shape observed in vivo. Furthermore, all the data of healthy RBC velocity vs liquid head are well represented by the same linear regression, independently on the donor. Preliminary results on beta-thalassemia RBCs are also presented and ...
ABSTRACT The flow-induced morphology of aqueous mixtures of gelatin and dextran was investigated ... more ABSTRACT The flow-induced morphology of aqueous mixtures of gelatin and dextran was investigated during gelation of the dispersed phase. Mixtures with 5% volume fraction of the gelatin-rich phase dispersed in the dextran-rich phase were sheared in a translating parallel plate apparatus coupled with an optical microscope. Gelation of the dispersed phase was brought about by decreasing mixture temperature under flow. As a consequence of gelation, the dispersed phase aggregated, forming clusters of gelled, partially coalesced, spherical particles. Cluster size was found to depend on the shear rate applied during gelation and on the temperature profile. Indeed, smaller clusters were formed: (a) under faster flows, (b) if the temperature was decreased to lower levels, and (c) if gelation was induced under quiescent conditions and the flow started only afterwards. By acting on these parameters, it is possible to suppress or enhance cluster formation and to tune cluster size. When the temperature was increased again above the gelation temperature, the gelled particles melted and the clusters rapidly coalesced. (C) 2002 The Society of Rheology.
Drop deformation in equiviscous polymer blends with dispersed phase volume fraction ranging from ... more Drop deformation in equiviscous polymer blends with dispersed phase volume fraction ranging from 0 to 10% has been investigated by video microscopy and image analysis in a parallel plate shear apparatus. Under steady external flow conditions the shape of individual drops, as measured by the three main axes, the orientation angle and the deformation parameter, showed marked time fluctuations around an average value depending on dispersed phase concentration and on drop capillary number. At small volume fractions the deformed shape was essentially coincident with the isolated drop case, whereas the higher the concentration, the larger the observed drop deformation at a given capillary number. Such deviations from the isolated drop case can be attributed to hydrodynamic interactions, mainly due to flow-induced collisions among drops. The experimental results can be conveniently described by a mean field approximation whereby the forces causing drop deformation are taken as proportional...
Industrial & Engineering Chemistry Research, 2002
We study transient drop deformation in dilute emulsions for large values of the capillary number ... more We study transient drop deformation in dilute emulsions for large values of the capillary number Ca. We consider steady planar linear flows characterized by the dimensionless vorticity ‚. For drop-to-matrix viscosity ratios Ï < 1, we find that the drops are strongly elongated by the extensional component of the flow and widen along the vorticity direction because of the compressional
This work is focused on the investigation of coalescence under shear flow in aqueous mixtures of ... more This work is focused on the investigation of coalescence under shear flow in aqueous mixtures of Na-alginate and Na-caseinate. Shear flow was generated in a parallel plate apparatus coupled with an optical microscope. Drop size distribution was measured as a function of time by computer controlled 3D optical sectioning of the sample and offline image analysis. Automated procedures of image
Aria is a plant hosting a$${350}\,\hbox {m}$$350mcryogenic isotopic distillation column, the tall... more Aria is a plant hosting a$${350}\,\hbox {m}$$350mcryogenic isotopic distillation column, the tallest ever built, which is being installed in a mine shaft at Carbosulcis S.p.A., Nuraxi-Figus (SU), Italy. Aria is one of the pillars of the argon dark-matter search experimental program, lead by the Global Argon Dark Matter Collaboration. It was designed to reduce the isotopic abundance of$${^{39}\hbox {Ar}}$$39Arin argon extracted from underground sources, called Underground Argon (UAr), which is used for dark-matter searches. Indeed,$${^{39}\hbox {Ar}}$$39Aris a$$\beta $$β-emitter of cosmogenic origin, whose activity poses background and pile-up concerns in the detectors. In this paper, we discuss the requirements, design, construction, tests, and projected performance of the plant for the isotopic cryogenic distillation of argon. We also present the successful results of the isotopic cryogenic distillation of nitrogen with a prototype plant.
The deformation of an isolated drop immersed in an immiscible liquid phase undergoing shear flow ... more The deformation of an isolated drop immersed in an immiscible liquid phase undergoing shear flow has been the subject of a number of studies, both theoretical and experimental, as reviewed by Rallison (1984) and by Stone (1994). The dynamics of an isolated sheared drop can be regarded as a sort of elementary event, which can provide some insight into the complex rheological behavior of a flowing dispersion of drops, such as the one encountered in emulsions, polymer blends and food industry.
... S. Guido Corresponding Author Contact Information , E-mail The Corresponding Author , a , M. ... more ... S. Guido Corresponding Author Contact Information , E-mail The Corresponding Author , a , M. Simeone a and F. Greco b. ... The slope of the fitting line (within experimental error) is equal to 2, in agreement with the assumption of second-order fluids made in the theoretical analysis ...
ABSTRACT This paper presents a simulative analysis of the energy efficiency of solar aided biomas... more ABSTRACT This paper presents a simulative analysis of the energy efficiency of solar aided biomass gasification for pure hydrogen production. Solar heat has been considered as available at 250 °C in three gasification processes: i) gasification reactor followed by two water gas shift reactors and a pressure swing adsorber; ii) gasification reactor followed by an integrated membrane water gas shift reactor; iii) supercritical gasification reactor followed by two flash separators and a pressure swing adsorber. Simulations are performed with the commercial software Aspen Plus® by considering biomass moisture content and the amount of solar heat as system variables. Results are presented in terms of energy and exergy system efficiency and are discussed and compared with the case of no solar integration.
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