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Mn-WO3/TiO2 catalysts were investigated for Selective Catalytic Reduction (SCR) of NO with NH3. The catalysts were synthesized by wetness impregnation method with different Mn loadings (1.5-3-12 wt%) on 8wt%WO3/TiO2. All three catalysts were compared with 8wt%WO3/TiO2 and bare MnOx oxide, used as references. The 1.5wt%Mn-8wt%WO3/TiO2 exhibited the highest performance in NO conversion and N2 selectivity. A commercial catalyst, based on titania supported vanadia and tungsta, (V2O5-WO3/TiO2), widely used for its high efficiency, was also investigated in the present work. The morphological, structural, redox and electronic properties of the catalysts and their thermal stability were studied by several techniques (N2 adsorption/desorption, X-ray diffraction, H2 temperature-programmed reduction, NH3 temperature programmed desorption, X-ray photoelectron spectroscopy).The aim of this paper is to study the effect of different Mn loadings on 8wt%WO3/TiO2 with the ambition to obtain highly active and selective catalysts in a large window of temperature. The replacement of toxic vanadium used in the classic V2O5-WO3/TiO2 catalyst with MnOx in the best performing catalyst, 1.5wt%Mn-8wt%WO3/TiO2, represents an important achievement to improve the environmental sustainability.

We analysed 13 years of the Neil Gehrels Swift Observatory survey data collected on the High Mass X-ray Binary IGR J18214-1318. Performing the timing analysis we detected a periodic signal of 5.42 d. From the companion star characteristics we derived an average orbital separation of $\sim 41 \rm R_{\odot}\simeq 2 R_{\star}$. The spectral type of the companion star (O9) and the tight orbital separation suggest that IGR~J18214-1318 is a wind accreting source with eccentricity lower than 0.17. The intensity profile folded at the orbital period shows a deep minimum compatible with an eclipse of the source by the companion star. In addition, we report on the broad-band 0.6--100 keV spectrum using data from XMM-Newton, NuSTAR, and Swift, applying self-consistent physical models. We find that the spectrum is well fitted either by a pure thermal Comptonization component, or, assuming that the source is a neutron star accreting above the critical regime, by a combined thermal and bulk-motion Comptonization model. In both cases, the presence of a local neutral absorption (possibly related to the thick wind of the companion star) is required., Comment: 7 pages, 7 figures. Accepted by MNRAS on 2020-08-17

The ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) Mini-Array will be composed of nine imaging atmospheric Cherenkov telescopes at the Observatorio del Teide site. The array will be best suited for astrophysical observations in the 0.3-200 TeV range with an angular resolution of few arc-minutes and an energy resolution of 10-15\%. A core-science programme in the first four years will be devoted to a limited number of key targets, addressing the most important open scientific questions in the very-high energy domain. At the same time, thanks to a wide field of view of about 10 degrees, ASTRI Mini-Array will observe many additional field sources, which will constitute the basis for the long-term observatory programme that will eventually cover all the accessible sky. In this paper, we review different astrophysical Galactic environments, e.g. pulsar wind nebulae, supernova remnants, and gamma-ray binaries, and show the results from a set of ASTRI Mini-Array simulations of some of these field sources made to highlight the expected performance of the array (even at large offset angles) and the important additional observatory science that will complement the core-science program., Comment: Accepted for publication in Journal of High-Energy Astrophysics

The ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) Project led by the Italian National Institute for Astrophysics (INAF) is developing and will deploy at the Observatorio del Teide a mini-array (ASTRI Mini-Array) composed of nine telescopes similar to the small-size dual-mirror Schwarzschild-Couder telescope (ASTRI-Horn) currently operating on the slopes of Mt. Etna in Sicily. The ASTRI Mini-Array will surpass the current Cherenkov telescope array differential sensitivity above a few tera-electronvolt (TeV), extending the energy band well above hundreds of TeV. This will allow us to explore a new window of the electromagnetic spectrum, by convolving the sensitivity performance with excellent angular and energy resolution figures. In this paper we describe the Core Science that we will address during the first four years of operation, providing examples of the breakthrough results that we will obtain when dealing with current open questions, such as the acceleration of cosmic rays, cosmology and fundamental physics and the new window, for the TeV energy band, of the time-domain astrophysics., Comment: Published in Journal of High Energy Astrophysics. 46 Figures, 7 Tables

We present the results of the broadband X-ray spectral analysis of simultaneous NuSTAR and XMM-Newton observations of four nearby Compton-thick active galactic nuclei (AGN) candidates selected from the Swift Burst Alert Telescope 150 month catalog. This work is part of a larger effort to identify and characterize all Compton-thick (N H ≥ 1024 cm−2) AGN in the local universe (z ≤ 0.05). We used three physically motivated models—MYTorus, borus02, and UXClumpy—to fit and characterize these sources. Of the four candidates analyzed, 2MASX J02051994-0233055 was found to be an unobscured (N H < 1022 cm−2) AGN, 2MASX J04075215-6116126 and IC 2227 to be Compton-thin (1022 cm−2 < N H < 1024 cm−2) AGN, and one, ESO 362−8, was confirmed to be a Compton-thick AGN. Additionally, every source was found to have a statistically significant difference between their line-of-sight and average torus hydrogen column density, further supporting the idea that the obscuring material in AGN is inhomogeneous. Furthermore, half of the sources in our sample (2MASX J02051994-0233055 and 2MASX J04075215-6116126) exhibited significant luminosity variation in the last decade, suggesting that this might be a common feature of AGN.

We present the combined Chandra and Swift-BAT spectral analysis of nine low-redshift (z ≤ 0.10), candidate heavily obscured active galactic nuclei (AGN) selected from the Swift-BAT 150 month catalog. We located soft (1−10 keV) X-ray counterparts to these BAT sources and joint fit their spectra with physically motivated models. The spectral analysis in the 1−150 keV energy band determined that all sources are obscured, with a line-of-sight column density N H ≥ 1022 cm−2 at a 90% confidence level. Four of these sources show significant obscuration with N H ≥ 1023 cm−2 and two additional sources are candidate Compton-thick Active Galactic Nuclei (CT-AGNs) with N H ≥ 1024 cm−2. These two sources, 2MASX J02051994–0233055 and IRAS 11058−1131, are the latest addition to the previous 3 CT-AGN candidates found using our strategy for soft X-ray follow-up of BAT sources. Here we present the results of our methodology so far, and analyze the effectiveness of applying different selection criteria to discover CT-AGN in the local Universe. Our selection criteria has an ∼20% success rate of discovering heavily obscured AGN whose CT nature is confirmed by follow-up NuSTAR observations. This is much higher than the ∼5% found in blind surveys.

Soybean hulls are one of the main by-products of soybean crushing and they are usually destined to become a putrescible waste. In a previous study, exhausted soybean hulls after the extraction of soybean peroxidase (an enzyme used for different applications) were employed as adsorbents of aqueous metal contaminants for water remediation [1]. In this work, such waste of soybean hulls were subjected to an acid-base treatment to isolate cellulose. The obtained material was functionalized with amino propyl groups [2] for the achievement of new sustainable materials with antimicrobial properties. For comparison purpose, analogous materials were synthesized starting from commercial cellulose. The amino-functionalization process resulted effective, since the antimicrobial activity of all the modified celluloses -tested by preliminary trials following the ASTM E 2149-2013 procedure- was outstanding against both Gram positive and Gram-negative bacteria. Particular attention was paid to the efficiency and sustainability of all the chemical processes with the use of waste materials, green solvents and sustainable procedures. The physical-chemical features of the samples were analyzed by several techniques such as electron scanning microscopy, infrared spectroscopy, thermogravimetry, differential scanning calorimetry. Preliminary results showed as the different synthetic procedures and the different starting cellulose samples influenced both the thermal stability and the microstructural order.

Nickel and nickel-ceria catalysts supported on high surface area silica, with 6 wt% Ni and 20 wt% CeO2 were prepared by microwave assisted (co) precipitation method. The catalysts were investigated by XRD, TPR and XPS analyses and they were tested in partial oxidation of methane (CPO). The catalytic reaction was carried out at atmospheric pressure in a temperature range of 400–800 °C with a feed gas mixture containing methane and oxygen in a molecular ratio CH4/O2 = 2. The Ni catalyst exhibited 60% methane conversion with 60% selectivity to CO already at 500 °C. On the contrary, the Ni–Ce catalyst was inert to CPO up to 700 °C. Moreover, the former catalyst reproduced its activity at the descending temperatures maintaining a good stability at 600 °C, over a reaction time of 80 h, whereas the latter one completely deactivated. Test of CH4 temperature programmed surface reaction (CH4-TPSR) revealed a higher methane activation temperature (> 100 °C) for the Ni–Ce catalyst as compared to the Ni one. Noticeable improvement of the ceria containing catalyst occurred when the reaction test started at a temperature higher than the methane decomposition temperature. In this case, the sample achieved the same catalytic behavior of the Ni catalyst. As confirmed by XPS analyses, the distinct electronic state of the supported nickel was responsible for the differences in catalytic behavior.

Modified MnOx catalysts with a cryptomelane (OMS-2) structure are prepared by a redox reaction between manganese sulfate and potassium permanganate solutions with different Mn/M molar ratio (10/1, 20/1), where M is Fe or Sn. Fe3+- or Sn4+-containing salts are used as precursors added at the stage of redox co-deposition. XRD, TEM, H2-TPR, TPO, XPS, and Raman spectroscopy techniques are used to study the features of the modified OMS-2 catalysts. It has been shown that the modifier cations can enter into the cryptomelane crystalline lattice, probably by substitution of Mn4+ and K+ ions into the tunnels or can be distributed on the surface of OMS-2 samples. Segregation of Sn2+ ions on the surface and in the subsurface layers of the modified Sn-OMS-2 catalysts preferentially takes place with a noticeable distortion of the initial OMS-2 structure. While, Fe3+ cations are homogeneously distributed between the surface and the crystalline structure of the Fe-OMS-2 samples. According to the H2-TPR data, the addition of Fe or Sn modifiers leads to an increase in the strength of oxygen binding with the catalyst surface. Under the TPO conditions, a shift of the O2 consumption to low temperatures (by >100 °C) is observed for the Sn-containing samples due to an increase of the amount of oxygen-deficient SnOx species that are formed as a result of SnO disproportionation. The modified sample Fe-OMS-2 (20/1) shows the highest selectivity towards acetaldehyde formation (>82%) at the ethanol conversion of 80% at 157 оC. The increase in the Fe content in the composition of the Fe-OMS-2 (10/1) sample results in the increase of T80% up to 180 °C, while keeping high selectivity towards acetaldehyde of 83%.

We report on the first detection of very high-energy (VHE) gamma-ray emission from the Crab Nebula by a Cherenkov telescope in dual-mirror Schwarzschild-Couder (SC) configuration. The result has been achieved by means of the 4 m size ASTRI-Horn telescope, operated on Mt. Etna (Italy) and developed in the context of the Cherenkov Telescope Array Observatory preparatory phase. The dual-mirror SC design is aplanatic and characterized by a small plate scale, allowing us to implement large field of view cameras with small-size pixel sensors and a high compactness. The curved focal plane of the ASTRI camera is covered by silicon photo-multipliers (SiPMs), managed by an unconventional front-end electronics based on a customized peak-sensing detector mode. The system includes internal and external calibration systems, hardware and software for control and acquisition, and the complete data archiving and processing chain. The observations of the Crab Nebula were carried out in December 2018, during the telescope verification phase, for a total observation time (after data selection) of 24.4 h, equally divided into on- and off-axis source exposure. The camera system was still under commissioning and its functionality was not yet completely exploited. Furthermore, due to recent eruptions of the Etna Volcano, the mirror reflection efficiency was reduced. Nevertheless, the observations led to the detection of the source with a statistical significance of 5.4 sigma above an energy threshold of ~3 TeV. This result provides an important step towards the use of dual-mirror systems in Cherenkov gamma-ray astronomy. A pathfinder mini-array based on nine large field-of-view ASTRI-like telescopes is under implementation., 6 pages, 2 figures

Ag/CeO2 catalysts with a silver loading of 10 wt.% have been prepared by three different techniques: impregnation, Ag/CeO2 (imp), impregnation of prereduced CeO2, Ag/CeO2 (red-imp), and co-deposition precipitation, Ag-CeO2 (co-DP). The features of the prepared composites have been studied by low-temperature N2 sorption, TGA, XRF, TPR-H2, TEM HR, XPS and Raman spectroscopy. The Raman and XPS results show that the addition of silver to CeO2 significantly increases the defectiveness of CeO2 particles, and such an effect is a function of the preparation method. The Ag-CeO2 (co-DP) and Ag/CeO2 (red-imp) catalysts show enhanced interfacial Ag–CeO2 interaction caused by the epitaxial growth of silver particles (d111 = 2.35 A) on the CeO2 surface (d111 = 3.1 A) as well as high amount of oxygen vacancies. A morphology-dependent interplay between the oxygen vacancies and the strength of the Ag–CeO2 interaction has been revealed. Strengthening of the metal–support interaction enhances the catalytic activity of the composites in both CO oxidation and soot combustion.

Dual/binary Supermassive Black Hole (SMBH) systems are the inevitable consequence of the current Lambda Cold Dark Matter cosmological paradigm. In this context, we discuss here the properties of MCG+11-11-032, a local (z=0.0362) Seyfert 2 galaxy. This source was proposed as a dual AGN candidate on the basis of the presence of double-peaked [OIII] emission lines in its optical spectrum. MCG+11-11-032 is also an X-ray variable source and was observed several times by the Swift X-ray Telescope (XRT) on time scales from days to years. In this work, we analyze the SDSS-DR13 spectrum and find evidence for double-peaked profiles in all the strongest narrow emission lines. We also study the XRT light curve and unveil the presence of an alternating behavior of the intrinsic 0.3-10 keV flux, while the 123-month Swift BAT light curve supports the presence of almost regular peaks and dips almost every 25 months. In addition, the XRT spectrum suggests for the presence of two narrow emission lines with rest-frame energies of E~6.16 keV and E~6.56 keV. Although by considering only the optical emission lines, different physical mechanisms may be invoked to explain the kinematical properties, the X-ray results are most naturally explained by the presence of a binary SMBH in the center of this source. In particular, we evidence a remarkable agreement between the putative SMBH pair orbital velocity derived from the BAT light curve and the velocity offset derived by the rest-frame Delta_E between the two X-ray line peaks in the XRT spectrum (i.e. Delta_v~0.06c)., Comment: 11 pages, 9 figures, 3 tables. Accepted for publication in MNRAS

Among the considerable number of studies that can be carried out using muons, we pay specific attention to the radiography of volcanoes based on the same principle of the X-ray radiography of human body. Thanks to their high penetration capability, cosmic-ray muons can be used to reconstruct the density distribution of the interior of huge structures by measuring the attenuation induced by the material on the muon flux. In particular, the quantitative understanding of the inner structure of volcanoes is a key-point to forecast the dangerous stages of activity and mitigate volcanic hazards. The instrumental approach is currently based on the detection of muons crossing hodoscopes made up of scintillator planes. Unfortunately, these detectors are affected by a strong background comprised by accidental coincidence of vertical shower particles, horizontal high-energy electrons and upward going particles. We propose an alternative technique based on the detection of the Cherenkov light produced by muons. This can be achieved with an imaging atmospheric Cherenkov telescope composed of a high reflectivity optical system that focus the Cherenkov light onto a multi-pixel focal camera with fast read-out electronics. The Cherenkov light emitted by a muon is imaged on the camera as an annular pattern which contains information to reconstruct the direction of the incident muon. We have estimated that using the Cherenkov imaging technique for muon radiography of volcanoes gives the advantage of a negligible background and improved spatial resolution, compared to the majority of the particle detectors. We present results of simulations based on a telescope with a positioning resolution of 13.5 m which corresponds to an acceptance of 9 cm2 sr. The telescope is located 1500 m far from a toy-model volcano, namely, a cone with a base diameter of 500 m and a height of 240 m. We test the feasibility of the proposed method by estimating the minimum number of observation nights needed to resolve inner empty conduits of different diameter.

We present the joint NuSTAR and XMM-Newton spectral analysis in the 0.6-70 keV band of three candidate Compton thick (CT-) AGN selected in the 100-month Swift-BAT catalog. These objects were previously classified as CT-AGNs based on low quality Swift-XRT and Swift-BAT data, and had soft photon indices (Gamma>2.2) that suggested a potential overestimation of the line of sight column density. Thanks to the high-quality NuSTAR and XMM-Newton data we were able to determine that in all three objects the photon index was significantly overestimated, and two out of three sources are reclassified from CT to Compton thin, confirming a previously observed trend, i.e., that a significant fraction of BAT-selected, candidate CT-AGNs with poor soft X-ray data are reclassified as Compton thin when the NuSTAR data are added to the fit. Finally, thanks to both the good XMM-Newton spatial resolution and the high NuSTAR and XMM-Newton spectral quality, we found that the third object in our sample was associated to the wrong counterpart: the correct one, 2MASX J10331570+5252182, has redshift z=0.14036, which makes it one of the very few candidate CT-AGNs in the 100-month BAT catalog detected at z>0.1, and a rare CT quasar., 12 Pages, 4 Figures. Accepted for publication in ApJ

Transesterification is the main process to produce FAME biodiesel but is affected by some drawbacks related to the catalyst and by-products. The use of homogeneous basic catalyst hinder its recovery and imply the use of oils with low content of free fatty acids to prevent saponification. Moreover, glycerol production and separation adversely affects the final cost of biodiesel. In the present work, we explore an alternative process, the interesterification, which allows the one-pot synthesis of biodiesel and conversion of glycerol to triacetylglycerol. The reaction is catalyzed by acid heterogeneous nanomaterials, in particular, mesoporous Silica or Titania functionalized with acid groups. The activity of catalysts is monitored by GC-MS and fresh and spent catalysts are characterized by XRD, XPS, TGA and acidity measurements. Preliminary results show a correlation between conversion degree and acidity features of the catalysts.

Le impellenti problematiche ambientali e le conseguenti restrizioni normative legate ai parametri di emissione nonché all'utilizzo di combustibili alternativi hanno spinto la ricerca verso lo sviluppo di processi innovativi per la produzione di biocombustibili derivati da risorse rinnovabili e che non competano con la produzione agroalimentare. Nel panorama dei biocombustibili un ruolo di primo livello è occupato dal biodiesel. Sebbene si stiano sviluppando tecnologie innovative come il processo ecofiningTM di ENI, ad oggi la principale metodica per la produzione di biodiesel è la transesterificazione di oli vegetali. Tale processo, da cui si ottiene il FAME biodiesel ad oggi miscelato in tutti i diesel commerciali presenta diversi svantaggi, su tutti la produzione di glicerolo la cui rimozione dal biodiesel ne incrementa i costi di produzione. Nel presente lavoro viene utilizzata una metodica alternativa quale l'Interesterificazione, una reazione di scambio di acile tra i trigliceridi costituenti gli oli vegetali e un acetil estere.1-2 Tale reazione consente la contemporanea produzione di biodiesel e triacetilglicerolo che ne costituisce un additivo, inoltre l'utilizzo di catalizzatori acidi eterogenei rappresenta un ulteriore vantaggio consentendo anche l'utilizzo di oli vegetali esausti come materia prima. I test catalitici sono stati condotti utilizzando un trigliceride modello come il gliceriltriottanoato e acetato d'etile come donatore di acile in presenza di catalizzatori acidi portanti gruppi solfonici su ossidi mesoporosi quali SiO2 Al2O3 e TiO2. La conversione del gliceriltriottanoato in etil ottanoato e triacetilglicerolo è stata monitorata tramite analisi GC-MS. I risultati preliminari ottenuti hanno evidenziato una correlazione tra attività catalitica e caratteristiche sia strutturali che di acidità del catalizzatore.

The valorization of the biomass is, nowadays, considered an eco-sustainable approach for the production of biofuels and added value platform molecules. 5-HydroxyMethylFurfural (5-HMF) can be considered one of the most important molecule [1] obtained from the cellulosic part of biomass, starting from which various intermediates as polymer feedstocks, chemicals and fuels can be derived by mean of a thermal/acid catalysed process. In the present work, we investigated different solid sulfonic catalysts based on titania support on the hydrothermal dehydration of fructose to 5-HMF (Fig.1). The catalytic performance of the synthesized materials were evaluated in hydrothermal conditions leading to the formation of 5-HMF. The reaction was carried out at different temperature both in water and 50:50 water/organic solvent mixture (3:7 sec-BuOH/MIBK) biphasic batch during 3h of reaction. According to preliminary results, the best catalytic activity was achieved when the sulfonic group is directly linked to the titania support. For this catalyst a total fructose conversion with a yield in 5-HMF of 65 % was reached when water/organic solvent mixture was used as reaction medium. Interestingly, in the presence of the most performant catalyst, a very good yield of 5-HMF (ca. 50%) was reached also by using only water as solvent. The surface and structural properties of the catalysts were investigated by means of X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermo-gravimetrical analysis (TGA), N2 adsorption isotherms and acid capacity measurements performed on both fresh and spent materials. These material characterizations allowed to correlate the physical and chemical catalysts properties with their activity versus the reaction of fructose dehydration to 5-HMF.

The continuous depletion of conventional fossil fuel reserves and the concern about climate changes, enhanced by CO2 emission resulting from fossil fuel consumption, is driving nowadays a renewed interest in Fischer-Tropsch synthesis (FTS). Such gas-to liquid process is becoming particularly attractive when using bio syngas. This gas mixture, rich in CO and H2, derives indeed from biomass gasification and is characterized by a H2/CO ratio lower than the value of 2, appropriate for hydrocarbon syntheses [1]. In the present study, TiO2 supported cobalt catalysts are combined with iron, active in the water gas shift reaction (WGS), aiming to increase H2 in the synthesis reactor. To investigate the role of iron in different Fe/Co weight ratios, monometallic Co, Fe and bimetallic CoFe catalysts are prepared and tested in FTS. Structural and electronic properties of the obtained materials are investigated by XRD, TPR , XPS and TEM techniques. Mono metallic Co/TiO2 and Fe/TiO2 and two bimetallic catalysts (Co/Fe =1 and Co/Fe = 5) with a total metal loading of 12 wt% are synthetized by a microwave assisted co-precipitation procedure. The FTS tests are performed at 1atm in a fixed-bed flow reactor with reagent gas mixture of CO, H2 and He (CO:H2:He volume ratio of 1:1.7:2.3) using GHSV = 1.9 Lsyngas gcat-1 h-1 and a temperature range of 275-350 °C. Before test, the catalysts are reduced under H2 flow for 16 h at 350 °C. All the catalysts exhibit good CO conversion, due to the presence of highly dispersed Fe and Co nanoparticles favoured by the microwave assisted catalyst synthesis. In the bimetallic catalysts, as expected, the presence of iron enhances CO2 production and, as compared to the monometallic cobalt catalyst, it increases the selectivity to higher hydrocarbons. According to the structural characterization and to XPS results shown in Fig. 1, the better activity of the mixed 10Co2Fe/TiO2 catalyst can be related to the formation of metal carbides during reaction. Moreover, a direct correlation between catalyst reducibility and activity is clearly indicated by the TPR profiles shown in Fig. 2. High resolution TEM images evidence a mixture of amorphous and graphitic carbon over the spent catalysts, explaining some deactivation occurring during reaction. Overall, the results suggest that in order to have the desired FTS outcome, in terms of CO conversion and C5+ selectivity, it is important to play with the Fe/Co weight ratio. Indeed, a limited amount of Fe is beneficial because it provides an additional supply of H2 by the WGS reaction and at the same time it does not overwhelms the FTS reaction activated by cobalt. In virtue of this compromise the 10Co2Fe/TiO2 catalyst exhibits the best catalytic behavior.

The Cherenkov Telescope Array (CTA) is the major next-generation observatory for ground-based very-high-energy gamma-ray astronomy. It will improve the sensitivity of current ground-based instruments by a factor of five to twenty, depending on the energy, greatly improving both their angular and energy resolutions over four decades in energy (from 20 GeV to 300 TeV). This achievement will be possible by using tens of imaging Cherenkov telescopes of three successive sizes. They will be arranged into two arrays, one per hemisphere, located on the La Palma island (Spain) and in Paranal (Chile). We present here the optimised and final telescope arrays for both CTA sites, as well as their foreseen performance, resulting from the analysis of three different large-scale Monte Carlo productions.© 2019, We gratefully acknowledge financial support from the following agencies and organizations: State Committee of Science of Armenia, Armenia; The Australian Research Council, Astronomy Australia Ltd, The University of Adelaide, Australian National University, Monash University, The University of New South Wales, The University of Sydney, Western Sydney University, Australia; Federal Ministry of Science, Research and Economy, and Innsbruck University, Austria; Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq), Fundacao de Amparo a Pesquisa do Estado do Rio de Janeiro (FAPERJ), Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP), Ministry of Science, Technology, Innovations and Communications (MCTIC), Brasil; Ministry of Education and Science, National RI Roadmap Project D01-153/28.08.2018, Bulgaria; The Natural Sciences and Engineering Research Council of Canada and the Canadian Space Agency, Canada; CONICYT-Chile grants PFB-06, FB0821, ACT 1406, FONDECYT-Chile grants 3160153, 3150314, 1150411, 1161463, 1170171, Pontificia Universidad Catolica de Chile Vice-Rectory of Research internationalization grant under MINEDUC agreement PUC1566, Chile, Croatian Science Foundation, Rudjer Boskovic Institute, University of Osijek, University of Rijeka, University of Split, Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, University of Zagreb, Faculty of Electrical Engineering and Computing, Croatia; Ministry of Education, Youth and Sports, MEYS LM2015046, LTT17006 and EU/MEYS CZ.02.1.01/0.0/0.0/16_013/0001403, CZ.02.1.01/0.0/0.0/17_049/0008422, Czech Republic; Ministry of Higher Education and Research, CNRS-INSU and CNRS-IN2P3, CEA-Irfu, ANR, Regional Council Ile-de France, Labex ENIGMASS, OSUG2020, P210 and OCEVU, France; Max Planck Society, BMBF, DESY, Helmholtz Association, Germany; Department of Atomic Energy, Department of Science and Technology, India; Istituto Nazionale di Astrofisica (INAF), Istituto Nazionale di Fisica Nucleare (INFN), MIUR, Istituto Nazionale di Astrofisica (INAF-OABRERA) Grant Fondazione Cariplo/Regione Lombardia ID 2014-1980/RST_ERC, Italy; ICRR, University of Tokyo, JSPS, MEXT, Japan; Netherlands Research School for Astronomy (NOVA), Netherlands Organization for Scientific Research (NWO), Netherlands; University of Oslo, Norway; Ministry of Science and Higher Education, DIR/WK/2017/12, the National Centre for Research and Development and the National Science Centre, UMO-2016/22/M/ST9/00583, Poland; Slovenian Research Agency, Slovenia, grants P1-0031, P1-0385, 10-0033, J1-9146; South African Department of Science and Technology and National Research Foundation through the South African Gamma-Ray Astronomy Programme, South Africa; MINECO National R+D+I, Severo Ochoa, Maria de Maeztu, CDTI, PAIDI, UJA, FPA2017-90566-REDC, Spain; Swedish Research Council, Royal Physiographic Society of Lund, Royal Swedish Academy of Sciences, The Swedish National Infrastructure for Computing (SNIC) at Lunarc (Lund), Sweden; Swiss National Science Foundation (SNSF), Ernest Boninchi Foundation, Switzerland; Durham University, Leverhulme Trust, Liverpool University, University of Leicester, University of Oxford, Royal Society, Science and Technology Facilities Council, UK; U.S. National Science Foundation, U.S.Department of Energy, Argonne National Laboratory, Barnard College, University of California, University of Chicago, Columbia University, Georgia Institute of Technology, Institute for Nuclear and Particle Astrophysics (INPAC-MRPI program), Iowa State University, the Smithsonian Institution, Washington University McDonnell Center for the Space Sciences, The University of Wisconsin and the Wisconsin Alumni Research Foundation, USA. The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreements no 262053 and no 317446. This project is receiving funding from the European Union's Horizon 2020 research and innovation programs under agreement no 676134.

Catalytic partial oxidation of methane (CPO) to synthesis gas was performed over differently prepared CeO2 supported nickel catalysts with 6 wt% Ni content. The samples were synthesized by microwave assisted procedures and by hydrothermal deposition procedure. Differences in the catalyst structural properties of the prepared catalysts were detected by XRD, TPR and XPS measurement. When tested at atmospheric pressure with feed gas mixture containing methane and oxygen in molecular ratio CH4/O-2 = 2, all the samples reached 98% conversion with CO selectivity values >95% in the 700-800 degrees C temperature range. The samples exhibited different behavior towards carbon formation during the tests. Moreover, according to XRD, XPS and TGA results, when the carbon was formed it did not cause catalyst deactivation. TPR profiles confirmed different degree of chemical interaction between NiO and CeO2 support, depending on the preparation method. The building up or the easy removal of carbon during the CH4 temperature programmed surface reaction (TPSR), substantiate the role of the CeO2 lattice oxygen mobility, enhanced by metal-support interaction, in the removal of the deposited carbon through CO evolution. Structure-activity relationship established a close dependence of the CPO performance on the combination of NiO and CeO2 crystallite sizes and the interaction between the two. (C) 2016 Elsevier B.V. All rights reserved.

IGR J16195-4945 is a hard X-ray source discovered by INTEGRAL during the Core Program observations performed in 2003. We analyzed the X-ray emission of this source exploiting the Swift-BAT survey data from December 2004 to March 2015, and all the available Swift-XRT pointed observations. The source is detected at a high significance level in the 123-month BAT survey data, with an average 15-150 keV flux of the source of ~1.6 mCrab. The timing analysis on the BAT data reveals with a significance higher than 6 standard deviations the presence of a modulated signal with a period of 3.945 d, that we interpret as the orbital period of the binary system. The folded light curve shows a flat profile with a narrow full eclipse lasting ~3.5% of the orbital period. We requested phase-constrained XRT observations to obtain a more detailed characterization of the eclipse in the soft X-ray range. Adopting resonable guess values for the mass and radius of the companion star, we derive a semi-major orbital axis of ~31 R_sun, equivalent to ~1.8 times the radius of the companion star. From these estimates and from the duration of the eclipse we derive an orbital inclination between 55 and 60 degrees. The broad band time-averaged XRT+BAT spectrum is well modeled with a strongly absorbed flat power law, with absorbing column N_H=7x 10^22 cm^(-2) and photon index Gamma=0.5, modified by a high energy exponential cutoff at E_cut=14 keV., Comment: 5 pages, 5 figures, 2 tables. Published on MNRAS

We present the combined NuSTATR and XMM-Newton 0.6-79 keV spectral analysis of a Seyfert 2 galaxy, NGC 1358, which we selected as a candidate Compton thick (CT-) active galactic nucleus (AGN) on the basis of previous Swift/BAT and Chandra studies. According to our analysis, NGC 1358 is confirmed to be a CT-AGN using physical motivated models, at >3 $\sigma$ confidence level. Our best-fit shows that the column density along the 'line-of-sight' of the obscuring material surrounding the accreting super-massive black hole is N$\rm _H$ = [1.96--2.80] $\times$ 10$^{24}$ cm$^{-2}$. The high-quality data from NuSTAR gives the best constraints on the spectral shape above $\sim$10 keV to date on NGC 1358. Moreover, by combining NuSTAR and XMM-Newton data, we find that the obscuring torus has a low covering factor ($f_c$, Comment: 12 pages, 6 figures

In recent years, considerable efforts have been done to reduce worldwide fossil fuels dependence exploiting renewable feedstock for the production of biofuels and thus reducing greenhouse gas emission. In this context, there has been a revitalized interest for the Fischer-Tropsch synthesis (FTS) (1) applied in the valorisation of biomass for the biofuels production. In particular, improvements in the catalytic efficiency of classical Fe and Co based catalysts have been driven by the need to enhance the characteristic low H2/CO ratio of biomass-derived syngas. Under these conditions, Fe has a low FTS catalytic efficiency but is able to promote the water gas shift reaction (WGS) (2) with the result of increasing the H2 content of the reaction mixture. Cobalt shows a better catalytic activity toward medium and long chain hydrocarbons but can undergo partial deactivation/sintering at high temperature.1-3 FTS: CO + 2H2 ? -CH2- + H2O (1) WGS: CO + H2O ? H2 + CO2 (2) According to these premises, in the present work the catalytic efficiency of mono- and bimetallic Fe/Co catalysts on the FTS on biomass-derived syngas, was investigated keeping into account the effect of the metal loadings, the different supports (SiO2, TiO2 and Al2O3) and the different reaction conditions. The materials were synthesised by a microwave assisted co-precipitation procedure and tested at atmospheric pressure in a flow reactor using different H2/CO feed ratio, temperature and flow rate. The surface and structural properties of the catalysts were investigated by means of N2 adsorption isotherms (BET), temperature programmed reduction analysis (TPR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) performed on fresh and spent materials. Preliminary results show a direct correlation between the catalytic efficiency and the nature and surface area of the support used.

We present the analysis of a sample of 35 candidate Compton thick (CT-) active galactic nuclei (AGNs) selected in the nearby Universe (average redshift ~0.03) with the Swift-BAT 100-month survey. All sources have available NuSTAR data, thus allowing us to constrain with unprecedented quality important spectral parameters such as the obscuring torus line-of-sight column density (N_{H, z}), the average torus column density (N_{H, tor}) and the torus covering factor (f_c). We compare the best-fit results obtained with the widely used MyTorus (Murphy et al. 2009) model with those of the recently published borus02 model (Balokovic et al. 2018) used in the same geometrical configuration of MyTorus (i.e., with f_c=0.5). We find a remarkable agreement between the two, although with increasing dispersion in N_{H, z} moving towards higher column densities. We then use borus02 to measure f_c. High-f_c sources have, on average, smaller offset between N_{H, z} and N_{H, tor} than low-f_c ones. Therefore, low f_c values can be linked to a "patchy torus" scenario, where the AGN is seen through an over-dense region in the torus, while high-f_c objects are more likely to be obscured by a more uniform gas distribution. Finally, we find potential evidence of an inverse trend between f_c and the AGN 2-10 keV luminosity, i.e., sources with higher f_c values have on average lower luminosities., Comment: 35 Pages, 23 Figures. Accepted for publication in ApJ

La0.6Sr0.4Fe0.6Mn0.4O3-? (LSFM) perovskite-type catalysts were prepared by a nanocasting route based on solution combustion synthesis, called the soft-hard templating (SHT) approach. Three silica hard templates with different textural properties were used to increase the specific surface area of the perovskites, and hence to improve their electrochemical activity for both oxygen evolution and reduction reactions. Careful structural and physicochemical characterization revealed that the materials are composites formed by crystalline LSFM perovskite and amorphous metal silicates, even after the etching procedure. Both the composites' specific surface area and the fraction of silicates are proportional to the silicas pore volume. Interestingly, the LSFM perovskite obtained by SHT has lower cell volumes than the parent oxide prepared without a silica template. The electrochemical characterization revealed the contrasting effects of the metal silicates on the performances of the electrodes. The LSFM-SHT-based electrodes have higher double-layer capacitance and higher current for oxygen evolution than those prepared with the parent LSFM. Furthermore, the LSFM-SHT-based electrodes show a preferential 4-electron pathway during the oxygen reduction reaction, if the amount of amorphous silicates is low (Si wt % < 3.5 wt %). However, the silicates also shift the onset potential of both oxygen evolution and reduction reactions to more positive and negative potential values, respectively, thus delaying the two reactions.

We present X-ray observations of the active galactic nucleus (AGN) in NGC 4785. The source is a local Seyfert 2 which has not been studied so far in much detail. It was recently detected with high significance in the 15-60 keV band in the 66-month Swift/BAT (Burst Array Telescope) all sky survey, but there have been no prior pointed X-ray observations of this object. With Suzaku, we clearly detect the source below 10 keV, and find it to have a flat continuum and prominent neutral iron fluorescence line with equivalent width ≳1 keV. Fitting the broad-band spectra with physical reflection models shows the source to be a Compton-thick AGN with N_H of at least 2 × 10^24 cm^-2 and absorption-corrected 2-10 keV X-ray power L_2-10 ∼ few times 10^42 erg s^-1. Realistic uncertainties on L_2-10 computed from the joint confidence interval on the intrinsic power-law continuum photon index and normalization are at least a factor of 10. The local bona fide Compton-thick AGN population is highly heterogeneous in terms of WISE mid-infrared source colours, and the nucleus of NGC 4785 appears especially sub-dominant in the mid-infrared when comparing to other Compton-thick AGN. Such sources would not be easily found using mid-infrared selection alone. The extent of host galaxy extinction to the nucleus is not clear, though NGC 4785 shows a complex core with a double bar and inner disc, adding to the list of known Compton-thick AGN in barred host galaxies.

Two series of Ni (6 wt%) catalysts supported over CeO 2 , La 2 O 3 and mixed CeO 2 –La 2 O 3 were prepared by co-precipitation and by wet-impregnation. The effect of the two Ni loading procedures on the catalyst structural properties was investigated by XRD, TPR and XPS. The catalytic behavior of the catalysts was tested in the methane partial oxidation reaction performed at 1 atm in a temperature range of 400–800 °C using dilute feed gas mixture with CH 4 /O 2 = 2 and gas hourly space velocity of 60,000 ml g −1 h −1 . Total methane combustion was observed within the 450 °C ≤ T ≤ 650 °C temperature range. Above 650 °C partial oxidation of methane started to occur, reaching at 800 °C a CO selectivity close to 90%. The lanthanum containing catalysts prepared by wet impregnation exhibited higher CPO activity at lower temperature as compared to the co-precipitated ones. Opposite behavior was observed with the Ni–CeO 2 catalysts. During the stability test at high temperature, carbon formed only over the single oxide supported catalysts, Ni–CeO 2 and Ni–La 2 O 3 . According to the characterization results carbon was not responsible for catalyst deactivation but it prevented the sintering of the nickel particle. The interplay of the crystallite sizes and the formation of various nickel–lanthanum oxide species with different Ni oxidation states were responsible for the differences in the CPO performance.

We present the combined Chandra and Swift-BAT spectral analysis of seven Seyfert 2 galaxies selected from the Swift-BAT 100-month catalog. We selected nearby (z=1E23 cm^(-2) at a >99% confidence level. Moreover, one to three sources are candidate Compton thick Active Galactic Nuclei (CT-AGN), i.e., have NH>=1E24 cm^(-2). We also test the recent "spectral curvature" method developed by Koss et al. (2016) to find candidate CT-AGN, finding a good agreement between our results and their predictions. Since the selection criteria we adopted have been effective in detecting highly obscured AGN, further observations of these and other Seyfert 2 galaxies selected from the Swift-BAT 100-month catalog will allow us to create a statistically significant sample of highly obscured AGN, therefore better understanding the physics of the obscuration processes., 8 pages, 3 figures. Accepted for publication in the Astrophysical Journal

The accretion-powered X-ray pulsar 4U 1626--67 is one of the few highly magnetized pulsars that accretes through Roche-lobe overflow from a low-mass companion. The characteristics of its broadband spectrum are similar to those of X-ray pulsars hosted in a high-mass X-ray binary systems, with a broad resonant cyclotron scattering feature (CRSF) at $\sim$37 keV. In this work, we examine the pulse-resolved and the pulse-averaged broadband spectrum using data from NuSTAR and Swift. We use the Becker & Wolff model of bulk+thermal Comptonization to infer key physical parameters of the accretion column flow and a broadband model for the disk reflected spectrum. In the softer X-ray band, we need to add a soft black-body component with $kT_{\rm bb}$ $\sim$0.5 keV, whose characteristics indicate a possible origin from the neutron star surface. Residuals suggest that the shape of the cyclotron line could be more satisfactorily fitted using a narrow core and broader wings and, at higher energies, a second harmonic could be present at $\sim$61 keV., 13 pages, accepted for publication in MNRAS

Based on current models of the Cosmic X-ray Background (CXB), heavily obscured Active Galactic Nuclei (AGN) are expected to make up ~10% of the peak emission of the CXB and ~20% of the total population of AGN, yet few of these sources have been recorded and characterized in current surveys. Here we present the Chandra follow-up observation of 14 AGN detected by Swift-BAT. For five sources in the sample, NuSTAR observations in the 3-80 keV band are also available. The X-ray spectral fitting over the 0.3-150 keV energy range allows us to determine the main X-ray spectral parameters, such as the photon index and the intrinsic absorption, of these objects, and to make hypotheses on the physical structures responsible for the observed spectra. We find that 13 of the 14 objects are absorbed AGN, and one is a candidate Compton thick AGN, having intrinsic absorption NH>1E24 cm^{-2}. Finally, we verified that the use of NuSTAR observations is strategic to strongly constrain the properties of obscured AGN, since the best-fit values we obtained for parameters such as the power-law photon index and the intrinsic absorption NH changed sometimes significantly fitting the spectra with and without the use of NuSTAR data., 13 pages, 4 figures, 4 tables. Accepted for publication on ApJ

Il presente studio riguarda lo sviluppo di un processo sostenibile per la trasformazione di oli di frittura esausti in una miscela dei corrispondenti esteri metilici degli acidi grassi ed eteri tert-butilici del glicerolo come potenziale biocarburante finale. Il processo riguarda una trasformazione acido catalizzata, assistita dalle microonde, utilizzando come reagente il metil tert-butil etere (MTBE) commercialmente disponibile.

Cherenkov light is emitted when charged particles travel through a dielectric medium with velocity higher than the speed of light in the medium. The ground-based Imaging Atmospheric Cherenkov Telescopes (IACT), dedicated to the very-high energy γ -ray Astrophysics, are based on the detection of the Cherenkov light produced by relativistic charged particles in a shower induced by TeV photons interacting with the Earth atmosphere. Usually, an IACT consists of a large segmented mirror which reflects the Cherenkov light onto an array of sensors, placed at the focal plane, equipped by fast electronics. Cherenkov light from muons is imaged by an IACT as a ring, when muon hits the mirror, or as an arc when the impact point is outside the mirror. The Cherenkov ring pattern contains information necessary to assess both direction and energy of the incident muon. Taking advantage of the muon detection capability of IACTs, we present a new application of the Cherenkov technique that can be used to perform the muon radiography of volcanoes. The quantitative understanding of the inner structure of a volcano is a key-point to monitor the stages of the volcano activity, to forecast the next eruptive style and, eventually, to mitigate volcanic hazards. Muon radiography shares the same principle as X-ray radiography: muons are attenuated by higher density regions inside the target so that, by measuring the differential attenuation of the muon flux along different directions, it is possible to determine the density distribution of the interior of a volcano. To date, muon imaging of volcanic structures has been mainly achieved with detectors made up of scintillator planes. The advantage of using Cherenkov telescopes is that they are negligibly affected by background noise and allow a consistently improved spatial resolution when compared to the majority of the current detectors.

Biodeterioration of stone monuments represents a critical issue for the preservation and conservation of Cultural Heritage, since different biological attacks may affect archeological areas, statues, buildings and hypogea contexts. Commercial products are commonly used as anti-biodeteriogeneous agents in traditional restoration treatments. Unfortunately, they are often toxic and environmentally-unfriendly materials, easily subjected to a leaching process that could induce dispersion of the chemicals into the surroundings and produce an unstable effect. In order to obtain an eco-friendly product and to increase the durability of the protective treatment, a hybrid organic-inorganic system was designed by using suitable nanocarriers for a controlled release of biocide agents. This system consists of a beta-Cyclodextrin (beta-CD) derivative supported by mesoporous silica, loaded with BIOTIN R®, a commercial product successfully used for the protection of stones surfaces from the proliferation of algae and lichens. By acting with different release kinetics, according to the homing site of the biocide agent, this hybrid system should extend the efficacy of treatment for a longer time, if compared to traditional treatments, stabilize the compound on the stone surfaces and reduce the environmental impact. Both beta-Cyclodextrin and mesoporous silica are very suitable as nanocarriers for this purpose. In addition, due to its inorganic nature, silica has a strong chemical and physical compatibility with stone materials and it can be further processed for the production of more advanced systems. In this work, carboxymethyl-beta-Cyclodextrin sodium salts (CM-beta-CD) and hexagonal mesoporous silica (HMS) were used. The organic-inorganic hybrid system was prepared by functionalizing HMS with aminopropyl groups (HMS-NH2), which act as linker for anchoring the beta-CD. The grafting of the CM-beta-CD onto HMS-NH2 produced the HMSNH-CM-beta-CD system. Subsequently, the entrapment of BIOTIN R® was performed on the HMS-NH-CM-beta--CD samples. The hybrid system and its single components were characterized by surface chemical analysis (X-ray Photoemission Spectroscopy, XPS) and structural analysis (X-Ray Diffraction, XRD). Thermal analysis (TGA, DTA) and porosimetry by gas adsorption (BET) were performed in order to study the loading process of the biocide into the nanocarriers. The kinetics of release of the biocide from all the loaded samples (single CM-beta-CD, single HMS and HMS-NH-CM-beta-CD) was investigated by UV-VIS spectroscopy using an acidic solution simulating a typical urban polluted environment (rain water).

IGR J19149+1036 is a high-mass X-ray binary detected by INTEGRAL in 2011 in the hard X-ray domain. We have analysed the Burst Alert Telescope (BAT) survey data of the first 103 months of the Swift mission detecting this source at a significance level of ̃30 standard deviations. The timing analysis on the long-term BAT light curve reveals the presence of a strong sinusoidal intensity modulation of 22.25 ± 0.05 d, that we interpret as the orbital period of this binary system. A broad-band (0.3-150 keV) spectral analysis was performed combining the BAT spectrum and the X-Ray Telescope (XRT) spectra from the pointed follow-up observations. The spectrum is adequately modelled with an absorbed power law with a high-energy cutoff at ̃24 keV and an absorption cyclotron feature at ̃31 keV. Correcting for the gravitational redshift, the inferred magnetic field at the neutron star surface is Bsurf ̃ 3.6 × 1012 G.

We have analyzed the Swift data relevant to the high mass X-ray binary Swift J1816.7-1613. The timing analysis of the BAT survey data unveiled a modulation at a period of P_0=118.5+/-0.8 days that we interpret as the orbital period of the X-ray binary system. The modulation is due to a sequence of bright flares, lasting ~30 d, separated by long quiescence intervals. This behavior is suggestive of a Be binary system, where periodic or quasi-periodic outbursts are the consequence of an enhancement of the accretion flow from the companion star at the periastron passage. The position of Swift J1816.7-1613 on the Corbet diagram strengthens this hypothesis. The broad band 0.2-150 keV spectrum is well modeled with a strongly absorbed power-law with a flat photon index Gamma~ 0.2 and a cut-off at ~ 10 keV.

LaCoO3 perovskites substituted by Sr at the A site and/or by Fe at the B site have been prepared by the citrate method. Characterizations by several techniques, such as specific surface area (BET method), XRD, TPR, SEM, UV–vis in DRS mode, XPS and TGA analyses, have been performed. The so prepared La1−xSrxCo1−yFeyO3−δ perovskites are semiconductor materials showing band gap energy values from 1.9 to 3.2 eV. They displayed solar photocatalytic activity for the 2-propanol degradation in gas–solid regime. The photocatalytic results suggest that the perovskites containing Fe are less active and the activity decreases by increasing the Fe content, however the presence of iron avoids the catalyst deactivation. The best photocatalytic activity in the 2-propanol degradation was found for the sample La0.6Sr0.4CoO3−δ.

Ni nanoparticles doped with different amount of gold were supported on MgAl2O4 by deposition from aqueous metal sol producing a series of catalysts with different Au content. The sol procedure was allowed to obtain dispersed metal particles with different composition. The particle size and the particle composition of the sol were maintained even after being deposited on the support. The catalysts, characterized by several techniques such as TPR, XPS, XRD, TEM, HRTEM and EELS at the different stages of their life exhibited significant structural modification. In particular, thermal treatments in reducing and oxidizing environment produced NiAu alloy phases and NiO surface segregation, respectively. When testing for methane dry reforming with CO2 in temperature ramped reaction, the monometallic nickel catalyst was more active at lower temperature whereas the bimetallic catalysts were more active at higher temperature. The presence of gold slightly affected the CO/H2 ratio due to the occurrence of parallel reactions such as the reverse water gas shift reaction (RWGS). Both types of catalysts, monometallic and bimetallic ones, deactivated a little with time but the degree of activity loss was not in straightforward relation with Au content due to the different effect of gold on the stability and on the amount of carbon formation.

The covalent grafting of two amino-fullerene C60 derivatives (C60-LC-NH2 and C60-SC-NH2, LC = long chain and SC = short chain) onto the surface of TEMPO oxidized nanocrystalline cellulose (NCC-COOH) has been reported for the first time. These hybrids (NCC-LC-C60 and NCC-SC-C60) form stable colloidal suspensions at concentrations up to 0.5 mg/mL and act as effective photosensitizers for singlet oxygen production as demonstrated by the oxidation of L-methionine-methyl ester to the corresponding sulphoxide. Using the same approach, in a one-pot reaction both a fluorescent target molecule (FITC-LC-NH2) and the C60-LC-NH2 derivative have been successfully attached covalently onto the NCC-COOH surface. These hybrids, which showed no cytotoxicity on MCF-7 human breast cancer cells could be good candidates in photodynamic cancer therapy.

We study the behaviour of the cyclotron resonant scattering feature (CRSF) of the high mass X-ray binary Vela X-1 using the long-term hard X-ray monitoring performed by the Burst Alert Telescope (BAT) on board Swift. High statistics, intensity selected spectra were built along 11 years of BAT survey. While the fundamental line is not revealed, the second harmonic of the CRSF can be clearly detected in all the spectra, at an energy varying between $\sim 53$ keV and $\sim 58$ keV, directly correlated with the luminosity. We have further investigated the evolution of the CRSF in time, by studying the intensity selected spectra built along four 33-month time intervals along the survey. For the first time we find in this source a secular variation in the CRSF energy: independent of the source luminosity, the CRSF second harmonic energy decreases by $\sim 0.36$ keV/year between the first and the third time interval, corresponding to an apparent decay of the magnetic field of $\sim 3\times 10^{10}$ G/year. The intensity-cyclotron energy pattern is consistent between the third and the last time intervals. A possible interpretation for this decay could be the settling of an accreted mound that produces either a distortion of the poloidal magnetic field on the polar cap or a geometrical displacement of the line forming region. This hypothesis seems supported by the correspondance between the rate of the line shift per unit accreted mass and the mass accreted on the polar cap per unit area in Vela X-1 and Her X-1, respectively., 6 Pages, 4 figures. In press on MNRAS

We report on the first spectral and timing characterization of the transient X-ray source 1RXS J194211.9+255552 using all available data from the Swift X-ray satellite. We used 10 years of hard X-ray data from the Burst Alert Telescope (BAT) to characterize its long-term behaviour and to search for long periodicities, finding evidence for a periodic modulation at 166.5 $\pm$ 0.5 d, that we interpret as the orbital period of the source. The folded light curve reveals that the X-ray emission is mostly concentrated in a restricted phase-interval and we propose to associate 1RXS J194211.9+255552 to the class of the Be X-ray binaries. This is also supported by the results of the spectral analysis, where we used the BAT data and three pointed Swift/XRT observations to characterize the X-ray broad-band spectral shape. We found mild spectral variability in soft X-rays that can be accounted for by a varying local neutral absorber, while the intrinsic emission is consistent with a hard power law multiplied by a high-energy exponential cut-off as typically observed in this class of systems., 5 pages, 7 figures. Published in MNRAS

La1-xSrxCr1-yFeyO3-? (x=0, 0.1, 0.15, 0.2; y=0, 0.3, 0.5) perovskite-type oxide powders were synthesized by solution combustion synthesis and characterized by X-ray diffraction, X-ray photoelectron spectroscopy and H2-temperature programmed reduction. Selected compositions were studied by CH4-temperature programmed reduction in the absence and in the presence of H2S. Temperature programmed oxidation and structural characterizations were performed in order to discriminate the nature of residual deposits on the catalyst surface. The study about reduction in different based-methane mixture revealed that total and partial methane oxidation occurred in the range ~450-1000 °C independently of methane concentration. The H2S influence on methane oxidation was evaluated and experiments in CH4/H2S gas mixture indicated that La0.9Sr0.1Cr0.7Fe0.3O3-? oxidized CH4 to CO2 and CO, as well as H2S to SO2. La0.9Sr0.1Cr0.7Fe0.3O3-? was therefore identified a potential anode material for Intermediate Temperature - Solid Oxide Fuel Cells directly fed with CH4 in the presence of H2S.

Ce0.8Sm0.2O2Â−Âxpowders were synthesized by solution combustion synthesis using citric acid, cellulose and sucrose as single, or intimately mixed, fuels. The powders were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, N2sorption at −196°C, H2-temperature programmed reduction and thermogravimetric analyses. Textural properties of the powders were shaped by the peculiar employed fuel. The study of reducibility revealed that oxygen vacancies formation is mainly influenced by both parameters, specific surface area and total pore volume. The different tendency toward reduction played a key role in sintering under reducing atmosphere (4% H2/Ar), and Ce0.8Sm0.2O2Â−Âxprepared with sucrose showed, at scanning electron microscopy images, the highest average grain size. Impedance spectroscopy experiments in air disclosed different grain boundary resistances on the basis of synthesis fuel employed and, in particular, Ce0.8Sm0.2O2Â−Âxprepared with sucrose exhibited the best electrical performance. Solution combustion synthesis thereby was able to tailor the morphological and reduction properties of Ce0.8Sm0.2O2Â−Âxpowders affecting even the microstructure of sintered pellet.

We study the long-term spectral and timing behaviour of LS I +61$^{\circ}$303 in hard X-rays (15--150 keV) using $\sim$10 years of survey data from the $Swift$ Burst Alert Telescope (BAT) monitor. We focus on the detection of long periodicities known to be present in this source in multiple wavelengths. We clearly detect three periods: the shorter one at 26.48 days is compatible with the orbital period of the system; the second, longer, periodicity at 26.93 days, is detected for the first time in X-rays and its value is consistent with an analogous temporal feature recently detected in the radio and in the gamma-ray waveband, and we associate it with a modulation caused by a precessing jet in this system. Finally, we find also evidence of the long-term periodicity at $\sim$1667 d, that results compatible with a beat frequency of the two close, and shorter, periodicities. We discuss our results in the context of the multi-band behaviour of the physical processes of this source., Comment: 5 pages, 8 figures. Published in MNRAS

How the accreted mass settling on the surface of a neutron star affects the topology of the magnetic field and how the secular evolution of the binary system depends on the magnetic field change is still an open issue. We report evidence for a clear drop in the observed magnetic field in the accreting pulsar V0332+53 after undergoing a bright 3-month long X-ray outburst. We determine the field from the position of the fundamental cyclotron line in its X-ray spectrum and relate it to the luminosity. For equal levels of luminosity, in the declining phase we measure a systematically lower value of the cyclotron line energy with respect to the rising phase. This results in a drop of ~1.7 x 10^11 G of the observed field between the onset and the end of the outburst. The settling of the accreted plasma onto the polar cap seems to induce a distortion of the magnetic field lines weakening their intensity along the accretion columns. Therefore the dissipation rate of the magnetic field could be much faster than previously estimated, unless the field is able to restore its original configuration on a time-scale comparable with the outbursts recurrence time., 5 pages, 6 figures, Published on MNRAS Letter (2016)

Biomass represents, nowadays, one of the most interesting alternatives to the fossil fuel as font of energy. Different platform molecules can be obtained from biomass and used, as it or as derivatives, as green and sustainable products. Glycerol, principal by-product (10% wt) in the transesterification of oils, represents an available platform molecule to achieve value added-products. Recently, several heterogeneous acid catalysts (Amberlyst-15, zeolites, zirconia derivatives, sulfonic hybrid silica) [2 and reference herein] were studied on esterification reaction of glycerol with acetic acid to achieve the corresponding mono-(MAG), di-(DAG) and tri-(TAG) acetins. The present work deals with the synthesis, characterization and catalytic properties of new hybrid organic-inorganic catalysts containing sulphate or phosphate functions on the glycerol acetylation. Fresh materials were characterized by TGA, XPS and acidity. The catalytic reactions were performed by using a mass ratio of catalyst/glycerol of 5 wt% and molar ratio acetic acid/glycerol corresponding to 3:1 [2]. In order to compare the activity of the new catalysts with commercial ones, sulfonic (22wt% H2SO4@SiO2) and phosphonic (0.7-1.3 mmol/g) silica were purchased by Aldrich. Recycling experiments were performed over the most active systems. Silica-bonded N-propyl sulfamic acid (SBNPSA) (1) showed the best catalytic behaviour towards the conversion of glycerol into TAG. The comparison between SBNPSA and the commercial H2SO4@SiO2 showed an increase of TAG when commercial catalyst was used, but a better stability of the synthetized material during the cycles. The analysis of the catalytic activities indicates that the best performance is achieved when sulfonic function is strictly linked to the amino-propyl silica. A leaching of the acid group is showed during the cycles, for these reasons further investigations are addressed toward the use of more stable mesoporous supports as SBA type.