PARTICLE ACCELERATION AND NON-THERMAL EMISSION FROM GALAXY CLUSTERS

BRUNETTI GIANFRANCO The Korean Astronomical Society 2004 Journal of The Korean Astronomical Society Vol.37 No.5

The existence and extent of non-thermal phenomena in galaxy clusters is now well established. A key question in our understanding of these phenomena is the origin of the relativistic electrons which may be constrained by the modelling of the fine radio properties of radio halos and of their statistics. In this paper we argue that present data favour a scenario in which the emitting electrons in the intracluster medium (ICM) are reaccelerated in situ on their way out. An overview of turbulent-particle acceleration models is given focussing on recent time-dependent calculations which include a full coupling between particles and MHD waves.

Thermally rearranged mixed matrix membranes for CO₂ separation: An aging study

Brunetti, Adele,Cersosimo, Maurizio,Kim, Ju Sung,Dong, Guangxi,Fontananova, Enrica,Lee, Young Moo,Drioli, Enrico,Barbieri, Giuseppe Elsevier 2017 INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL Vol.61 No.-

<P><B>Abstract</B></P> <P>In this work, the aging behavior of a thermally rearranged polybenzoxazole-co-imide (TR-PBOI) mixed matrix membrane loaded with 0.5wt.% of oxidized multi-wall carbon nanotubes (MWCNT) was evaluated and then compared to a pure TR polymeric membrane prepared from the same precursor. To the best of authors knowledge, this is the first report of a mixed matrix membrane being prepared through the dispersion of MWCNTs within a thermally rearranged polymer matrix for CO<SUB>2</SUB> separation. Microporous structures were created in both membranes when thermally rearranged at 375°C, facilitating fast mass transfer ideal for membrane gas separation. The TR mixed matrix membrane with oxidized CNTs demonstrated improved separation properties with regard to both permeability and selectivity compared to the pure TR polymeric membrane due to a greater degree of thermal rearrangement (11.3%) than what was exhibited by the TR membrane (6.7%). Moreover, the high CO<SUB>2</SUB> solubility typical of TR polymers coupled with diffusivity enhancements improved the CO<SUB>2</SUB>/N<SUB>2</SUB> selectivity. The addition of oxidized CNTs to the TR-PBOI polymer did not significantly influence the aging behavior of the mixed matrix membrane. Both pure TR-PBOI and mixed matrix membranes exhibited an increase in CO<SUB>2</SUB> selectivity due to physical aging. The improved separation properties in conjunction with an unchanged membrane stability over time suggested that the addition of CNTs to pure TR membranes could be an excellent approach toward improving the performance of thermally rearranged membranes applied toward gas separation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Separation properties of a pure TR and a TR+CNTs mixed matrix membranes. </LI> <LI> Aging behavior of a pure TR and a TR+CNTs mixed matrix membranes. </LI> <LI> No significant difference observed in aging behavior of TR+CNT membrane with respect to pure TR membrane. </LI> <LI> TR+CNTs mixed matrix membrane more permeable and selective than pure TR membrane. </LI> </UL> </P>

In situ restoring of aged thermally rearranged gas separation membranes

Brunetti, Adele,Cersosimo, Maurizio,Dong, Guangxi,Woo, Kyung Take,Lee, Jongmyeong,Kim, Ju Sung,Lee, Young Moo,Drioli, Enrico,Barbieri, Giuseppe Elsevier 2016 Journal of membrane science Vol.520 No.-

<P><B>Abstract</B></P> <P>Physical aging in high free-volume polymer membranes is one of the main hurdles limiting their application in gas separation. The recovery of membrane separation properties without the need to disassemble the module, although challenging, would provide significant advantages for applications in various fields. In this work, an in situ restoring procedure for the recovery of mass transport in aged membrane modules made of thermally rearranged polymer membranes was developed in which the modules were exposed to methanol at 80°C. The thermally rearranged hollow fiber membrane modules were subjected to long-time operation to investigate their aging: the CO<SUB>2</SUB> and N<SUB>2</SUB> permeances were monitored at different temperatures, pressures, and feed compositions over a total period of 727 days with two long-time runs of 185 and 263 days, interspersed by a stand-by period of 240 days, and with each run followed by a restoring. In both long-time runs, CO<SUB>2</SUB> and N<SUB>2</SUB> permeance dropped as a result of aging, whereas the selectivity remained nearly constant. The permeances were fully recovered after the proposed restoring procedure was applied, demonstrating its efficacy and repeatability for membrane aging recovery, even for an extremely aged membrane exposed to various conditions for nearly two years.</P> <P><B>Highlights</B></P> <P> <UL> <LI> In-situ restoring of mass transport in aged membranes. </LI> <LI> Thermally rearranged polymer membranes. </LI> <LI> Periodic measures over years on thermally rearranged polymer membranes. </LI> <LI> Repeatability of in-situ restoring showing full permeation properties recovery. </LI> </UL> </P>

Membrane engineering for environmental protection and sustainable industrial growth: Options for water and gas treatment

Adele Brunetti,Francesca Macedonio,Giuseppe Barbieri,Enrico Drioli 대한환경공학회 2015 Environmental Engineering Research Vol.20 No.4

The increasing demand for materials, energy and products drives chemical engineers to propose new solutions everyday able to promote development while supporting sustainable industrial growth. Membrane engineering can offer significant assets to this development. Here, they are identified the most interesting aspects of membrane engineering in strategic industrial sectors such as water treatment, energy production and depletion and reuse of raw materials. The opportunity to integrate membrane units with innovative systems to exploit the potential advantages derived from their synergic uses is also emphasized. The analysis of the potentialities of these new technologies is supported by the introduction of process intensification metrics which provide an alternative and innovative point of view regarding the unit performance, highlighting important aspects characterizing the technology and not identified by the conventional analysis of the unit performance.

Antioxidant Effects of Garlic in Young and Aged Rat Brain In Vitro

Luigi Brunetti,Luigi Menghini,Giustino Orlando,Lucia Recinella,Sheila Leone,Francesco Epifano,Francesco Lazzarin,Annalisa Chiavaroli,Claudio Ferrante,Michele Vacca 한국식품영양과학회 2009 Journal of medicinal food Vol.12 No.5

Oxidative stress plays a key role in the pathogenesis of age-related neurodegeneration, and the nonenzymatic production of 8-iso-prostaglandin F2α (8-iso-PGF2α) may represent a reliable index of cellular oxidative damage. Garlic (Allium sativum) has been associated with peripheral antioxidant activities and therefore might prevent or reverse 8-iso-PGF2α production, but scant data are available on its possible neuroprotective effects. Therefore, we have studied the possible antioxidant effects of a garlic extract in rat brain synaptosomes obtained from young (3-month-old) and aged (14-month-old) male Wistar rats that were perfused, in vitro, with graded concentrations of a garlic extract (10–500μg/mL). Release in the effluent was evaluated, both in the basal state and after hydrogen peroxide-induced oxidative stress. In young rats, we observed a concentration-dependent inhibitory effect of the garlic extract on brain 8-iso-PGF2α production, both basally and after hydrogen peroxide-induced oxidative stimulus. In aged rats, 8-iso-PGF2α production was not affected by the garlic extract in the basal state, whereas, after hydrogen peroxide-induced oxidative stimulus, an antioxidant effect of the garlic extract appeared only at the higher concentration tested. In conclusion, garlic supplementation could be effective in preventing brain oxidative damage in young animals, whereas the aging brain seems to be resistant to the antioxidant effects of garlic, in vitro.

OCCURENCE AND LUMINOSITY FUNCTIONS OF GIANT RADIO HALOS FROM MAGNETO-TURBULENT MODEL

CASSANO R.,BRUNETTI G.,SETTI G. The Korean Astronomical Society 2004 Journal of The Korean Astronomical Society Vol.37 No.5

We calculate the probability to form giant radio halos (${\~}$ 1 Mpc size) as a function of the mass of the host clusters by using a Statistical Magneto-Turbulent Model (Cassano & Brunetti, these proceedings). We show that the expectations of this model are in good agreement with the observations for viable values of the parameters. In particular, the abrupt increase of the probability to find radio halos in the more massive galaxy clusters ($M {\ge} 2{\times}10^{15} M_{\bigodot}$) can be well reproduced. We calculate the evolution with redshift of such a probability and find that giant radio halos can be powered by particle acceleration due to MHD turbulence up to z${\~}$0.5 in a ACDM cosmology. Finally, we calculate the expected Luminosity Functions of radio halos (RHLFs). At variance with previous studies, the shape of our RHLFs is characterized by the presence of a cut-off at low synchrotron powers which reflects the inefficiency of particle acceleration in the case of less massive galaxy clusters.

HEATED INTRACLUSTER GAS AND RADIO CONNECTIONS: THE SINGULAR CASE OF MKW 3S

MAZZOTTA PASQUALE,BRUNETTI GIANFRANCO,GIACINTUCCI SIMONA,VENTURI TIZIANA,BARDELLI SANDRO The Korean Astronomical Society 2004 Journal of The Korean Astronomical Society Vol.37 No.5

Similarly to other cluster of galaxies previously classified as cooling flow systems, the Chandra observation of MKW 3s reveals that this object has a complex X-ray structure hosting both a X-ray cavity and a X-ray filament. Unlike the other clusters, however, the temperature map of the core of MKW 3s shows the presence of extended regions of gas heated above the radially averaged gas temperature at any radius. As the cluster does not show evidences for ongoing major mergers Mazzotta et al. suggest a connection between the heated gas and the activity of the central AGN. Nevertheless, due to the lack of high quality radio maps, this interpretation was controversial. In this paper we present the results of two new radio observations of MKW 3s at 1.28 GHz and 604 MHz obtained at the GMRT. Together with the Chandra observation and a separate VLA observation at 327 MHz from Young, we show unequivocal evidences for a close connection between the heated gas region and the AGN activity and we briefly summarize possible implications.

Process intensification strategies and membrane engineering

Drioli, Enrico,Brunetti, Adele,Di Profio, Gianluca,Barbieri, Giuseppe The Royal Society of Chemistry 2012 Green chemistry Vol.14 No.6

<P>An important contribution to the realization of industrial sustainable development can be given by “green process engineering”. Based on the principles of the Process intensification strategy it can lead to the development and the re-design of new processes more compact and efficient that allow the better exploitation of raw materials, a lower energy consumption and a reduced plant volume. Membrane technology contributes to the pursuit of these principles and, in the last few years, the potentialities of membrane operations have been widely recognized. In this work, an overview of membrane application and their perspectives in the field of hydrogen production and distillation will be analysed considering membrane reactors and membrane distillation as case studies. The scope is to show how the redesign as membrane systems of traditional operations might contribute to the realization of the goals of process intensification and green chemistry by a new “green process engineering”.</P> <P>Graphic Abstract</P><P>Green chemistry and green process engineering also mean new processes such as those based on membrane reactors and membrane contactors. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2gc16668b'> </P>

CLUSTER MERGERS AND NON-THERMAL PHENOMENA: A STATISTICAL MAGNETO-TURBULENT MODEL

CASSANO R.,BRUNETTI G. The Korean Astronomical Society 2004 Journal of The Korean Astronomical Society Vol.37 No.5

With the aim to investigate the statistical properties and the connection between thermal and non-thermal properties of the ICM in galaxy clusters, we have developed a statistical magneto-turbulent model which describes, at the same time, the evolution of the thermal and non-thermal emission from galaxy clusters. In particular, starting from the cosmological evolution of clusters, we follow cluster. mergers, calculate the spectrum of the magnetosonic waves generated in the ICM during these mergers, the evolution of relativistic electrons and the resulting synchrotron and Inverse Compton spectra. We show that the broad band (radio and hard x-ray) non-thermal spectral properties of galaxy clusters can be well accounted for by our model for viable values of the parameters (here we adopt a EdS cosmology).

A Pd Doped PVDF Hollow Fibre for the Dissolved Oxygen Removal Process

Batbieri G.,Brunetti A.,Scura F.,Lentini F.,Agostino R G.,Kim, M.J.,Formoso V.,Drioli E.,Lee, K.H. The Membrane Society of Korea 2006 Korean Membrane Journal Vol.8 No.1

In semiconductor industries, dissolved oxygen is one of the most undesirable contaminants of ultrapure water. A method for dissolved oxygen removal (DOR) consists in the use of polymeric hollow fibres, loaded with a catalyst and fed with a reducing agent such as hydrogen. In this work, PVDF hollow fibres loaded with Pd were characterized by means of perporometry, scanning electron microscopy (SEM), energy dispersive X-ray (EDX). The hollow fibre analyzed shows a five-layer structure with remarkable morphological differences. An estimation of pore diameters and their distribution was performed giving a mean pore diameter of 100 nm. The permeance and selectivity of the fibres were measured using $H_2,\;N_2,\;O_2$ as single gases, at different operating conditions. An $H_2$ permeance of $37 mmol/m^2s$ was measured and $H_2/O_2$ and $H_2/N_2$ selectivities of ca. 3 were obtained. $H_2$ permeance was 1/3 when a water stream flows in the shell side. Catalytic fibrebehaviour was simulated using a mathematical model for a loop membrane reactor, considering only $O_2$ and $H_2$ diffusive transport inside the membrane and their catalytic reaction. Dimensionless parameters such as the Thiele modulus are employed to describe the system behaviour. The model agrees well with the experimental reaction data.