Probing protoneutron star density profile from neutrino signals

Supernovae of Type II is a phenomenon that occurs at the end of evolution of massive stars when the iron core of the star exceeds a mass limit. After collapse of the core under gravity the shock wave alone does not succeed in expelling the mass of the star and in this sense the role of neutrinos is the most important mechanism to do so. During the emission of neutrinos flavor conversion is possible, related the phenomenon of oscillations, which however depends directly on the particular density profile of the medium. In this paper we present results of numerical simulations of neutrino flavor conversion in protoneutron stars and after collapse. The probabilities of survival for a given flavor in a complete three-flavors framework is estimated through an algorithm which conserves unitarity to a high degree of accuracy. The sensitivity of the results to the different adopted models for the protoneutron star structure is examined in detail demonstrating how the neutrino signal could be used to check the validity of models.Comment: 9 figure

Sequential biological and photocatalysis based treatments for shipboard slop purification: A pilot plant investigation

This study investigated the treatment of a shipboard slop containing commercial gasoline in a pilot plant scale consisting of a membrane biological reactor (MBR) and photocatalytic reactor (PCR) acting in series. The MBR contributed for approximately 70% to the overall slop purification. More precisely, the biological process was able to remove approximately 40%, on average, of the organic pollution in the slop. Nevertheless, the membrane was capable to retain a large amount of organic molecules within the system, amounting for a further 30% of the influent total organic content removal. However, this affected the membrane fouling, thus resulting in the increase of the pore blocking mechanism that accounted for approximately 20% to the total resistance to filtration (2.85∙10 13 m −1 ), even if a significant restoration of the original membrane permeability was obtained after chemical cleanings. On the other hand, the biological treatment produced a clear solution for the photocatalytic system, thereby optimizing the light penetration and generation of highly oxidizing active oxygen species that enabled the degradation of bio-recalcitrant compounds. Indeed, low total organic carbon (TOC) values (<10 mg L −1 ) were achieved in the output of the photocatalytic reactor by means of only 60 Einstein (E) of cumulative impinging energy after the addition of K 2 S 2 O 8 . Overall, coupling the two processes enabled very high TOC removal (ca. 95%)

Visible Light Induced Oxidation of Trans-ferulic Acid by TiO2 Photocatalysis

The oxidation of trans-ferulic acid (C 10H 10O 4) in aqueous TiO 2 dispersion occurs via the formation of a charge-transfer complex on the TiO 2 surface that is able to absorb visible light (\u3bb 65 400 nm). The main product is CO 2, whereas secondary oxidation products are organic species such as vanillin, caffeic acid, homovanillic acid, and vanillylmandelic acid. Oxidation through the formation of a charge-transfer complex occurs only in the presence of specific TiO 2 samples. Experiments in the absence of oxygen, in the presence of bromate ions and by using a phosphate-modified TiO 2, have been carried out for investigating the reaction mechanism. In order to study the interaction between trans-ferulic acid and TiO 2 surface and to characterize the charge-transfer complex, UV-Vis diffuse reflectance and FT-IR spectroscopies have been used. FT-IR characterization of TiO 2 samples in contact with the aqueous trans-ferulic acid solution indicates that the charge-transfer complex formation occurs via adsorption of bidentate ferulate species

The combination of heterogeneous photocatalysis with chemical and physical operations: a tool for improving the photoprocess performance

Heterogeneous photocatalysis is a process of great potential for pollutant abatement and waste treatment. In order to improve the overall performance of the photoprocess, heterogeneous photocatalysis is being combined with physical or chemical operations, which affect the chemical kinetics and/or the overall ef\ufb01ciency. This review addresses the various possibilities to couple heterogeneous photocatalysis with other technologies to photodegrade organic and inorganic pollutants dissolved in actual or synthetic aqueous ef\ufb02uents. These combinations increase the photoprocess ef\ufb01ciency by decreasing the reaction time in respect to the separated operations or they decrease the cost in respect of heterogeneous photocatalysis alone, generally in terms of light energy. Depending on the operation coupled with heterogeneous photocatalysis, two categories of combinations exist. When the coupling is with ultrasonic irradiation, photo-Fenton reaction, ozonation, or electrochemical treatment, the combination affects the photocatalytic mechanisms thus improving the ef\ufb01ciency of the photocatalytic process. When the coupling is with biological treatment, membrane reactor, membrane photoreactor, or physical adsorption, the combination does not affect the photocatalytic mechanisms but it improves the ef\ufb01ciency of the overall process. The choice of the coupling is related to the type of wastewater to be treated. A synergistic effect, giving rise to an improvement of the ef\ufb01ciency of the photocatalytic process, has been reported in the literature for many cases

Photocatalytic degradation of dyes by using a membrane reactor

Dyes are organic compounds used in textile, food and drug industries, and their abatement represents one of the main problems in the treatment processes because generally they are very stable toxic compounds. In this work, two commercial azo-dyes, i.e. Congo Red (C32H22N6Na2O6S2) and Patent Blue (C27H31N2NaO6S2), in aqueous solution were degraded in a photocatalytic membrane reactor by using TiO2 Degussa P25 as the catalyst. Different system con\ufb01gurations and irradiating sources were studied, and the in\ufb02uence of some operational parameters such as the pressure in the membrane cell and the initial concentration of the substrates was determined. A comparison between suspended and entrapped TiO2 was also done. The experimental results showed a satisfactory degradation ef\ufb01ciency of the photocatalytic membrane process. The in\ufb02uence of various parameters (e.g. feed concentration, recirculation rate) has been discussed to obtain high reaction rates, operating stability and high membrane rejection, both for substrates and by-products. Congo Red was photodegraded with higher rate under the same experimental conditions probably due to its higher adsorption onto the catalyst surface. It was possible to treat successfully highly concentrated solutions (500 mg/L) of both dyes by means of a continuous process obtaining good values of permeate \ufb02uxes (30\u201370 L/m2 h); this could be interesting for industrial applications. The reactor containing the suspended photocatalyst was signi\ufb01cantly more ef\ufb01cient than the reactor containing the catalyst entrapped into the membrane

Selective photooxidation of ortho-substituted benzyl alcohols and the catalytic role of ortho-methoxybenzaldehyde

It has been recently reported by Palmisano et al. (2015) [1] that the oxidation of 2-methoxybenzyl alcohol (2-MBA) to 2-methoxybenzaldehyde (2-MBAD) proceeds in water under near-UV light with an unexpected catalytic effect of 2-MBAD. In order to investigate the catalytic role of aldehyde in photolytic oxidation of ortho-substituted benzyl alcohols (OSBAs), reactivity runs were carried out with 2-methylbenzyl alcohol (2-MeBA), 2-nitrobenzyl alcohol (2-NBA), 2-hydroxybenzyl alcohol (2-HBA) and 2-chlorobenzyl alcohol (2-ClBA) in the absence and in the presence of their corresponding aldehyde. None of those alcohols showed a measurable oxidation rate even in the presence of their aldehydes but 2-NBA was oxidised very fast, although no corresponding carbonyl product was obtained. The possible catalytic role of 2-MBAD was investigated for the photolytic oxidation of 4-methoxybenzyl alcohol (4-MBA), 4-nitrobenzyl alcohol (4-NBA), 2-ClBA, 2-HBA, 2-MeBA and ferulic acid (FA). The results showed that 2-MBAD acts as a catalyst only for 4-MBA, 2-HBA and FA. The photocatalytic oxidation of OSBAs in the presence of powdered TiO2 has been also carried out in order to investigate the mutual influences, if any, between homogeneous and heterogeneous processes. The reactivity runs were carried out with TiO2 photocatalyst in water and under near-UV irradiation; a home-prepared (HP) TiO2 sample was used along with Degussa P25. HP catalyst showed the best performance: the 2-MBA half-life time was 5 times smaller and the selectivity to aldehyde 13 times higher than in the presence of Degussa P25

Selective aqueous oxidation of aromatic alcohols under solar light in the presence of TiO2 modified with different metal species

A set of metals modified TiO2 photocatalysts were prepared starting from titanium tetraisopropoxyde and different metal precursors to study the influence of the addition of the various foreign agents on the physico-chemical and photocatalytic properties of the catalysts. The powders were characterized by X-ray diffraction, Raman spectroscopy, specific surface area measurements, scanning electron microscopy, energy dispersive X-ray spectroscopy, UV–Vis diffuse reflectance spectroscopy, photoluminescence, temperature programmed desorption after CO2 adsorption. The photocatalytic activity was evaluated using as probe reactions the partial oxidation of three aromatic alcohols: benzyl alcohol (BA), 4-methoxy benzyl alcohol (4-MBA), and 4-hydroxy benzyl alcohol (4-HBA) under simulated solar light irradiation. Different oxidation and selectivity values were obtained for the three substrates depending not only on the type of metals but also on the nature and position of the substituent in the phenyl ring of benzyl alcohol. As a general behaviour, the doped samples allowed the achievement of a greater selectivity especially for 4-MBA even if sometimes with minor conversions. The presence of W or Nb was beneficial for both conversion and selectivity for all the substrates with respect to bare TiO2. Graphical abstract: [Figure not available: see fulltext.

Transmission of Xylella fastidiosa by naturally infected Philaenus spumarius (Hemiptera, Aphrophoridae) to different host plants.

© 2016 The Authors. Journal of Applied Entomology Published by Blackwell Verlag GmbH. The recent establishment of Xylella fastidiosa subspecies pauca in the southern Italian region of Apulia threatens agricultural crops and the environment. Olive is an important and widespread ancient crop in Italy and, so far, the most impacted host. The meadow spittlebug Philaenus spumarius (Hemiptera, Aphrophoridae) has been identified as a vector of X. fastidiosa in southern Italy; this species is one of the most common potential vectors in Europe. To generate disease management strategies, data on X. fastidiosa transmission by P. spumarius are necessary. Therefore, we carried out transmission experiments by using field-collected spittlebugs in 2014 and 2015 (5 and 11 collection dates, respectively), and transferring groups of insects immediately on to recipient plants. Various host plant species were tested: olive, oleander, sweet orange, grapevine and the stone fruit rootstock GF677 (Prunus persica × Prunus amygdalus). Xylella fastidiosa was detected in all the host plants after insect plant access except for grapevine; infections to sweet orange and stone fruit were not systemic. In 2015, estimates of insect X. fastidiosa infectivity were obtained; the number of PCR-positive P. spumarius on each plant was positively correlated with the plant infection status. The proportion of P. spumarius infected with X. fastidiosa ranged from 25% to 71% during the entire survey period. The number of X. fastidiosa cells detected in P. spumarius heads ranged from 3.5 × 10 to 4.0 × 102(CFU equivalents), which is lower than that reported for leafhopper vectors in the Americas. These data show that field-collected P. spumarius have high rates of X. fastidiosa infection and are competent vectors