390 research outputs found
The fate of binary stars hosting planets upon interaction with Sgr A* black hole
No full textOur Galaxy hosts a very massive object at its centre, often referred to as the supermassive black hole Sgr A*. Its gravitational tidal field is so intense that it can strip apart a binary star passing its vicinity and accelerate one of the components of the binary as hypervelocity star (HVS) and grab the other star as S-star. Taking into consideration that many binary star systems are known to host planets, in this paper we aim to broaden the study of the close interaction of binary stars and their planetary systems with Sgr A* massive object. Results are obtained via a high-precision N-body code including post-Newtonian approximation. We quantify the likelihood of capture and ejection of stars and planets after interaction with Sgr A*, finding that the fraction of stars captured around it is about three times that of the planets (∼49.4 per cent versus ∼14.5 per cent) and the fraction of hypervelocity planet ejection is about twice that of HVSs (∼21.7 per cent versus ∼9.0 per cent). The actual possibility of observational counterparts deserves further investigation
Stability of planetary systems within the S-star cluster: The Solar system analogues
No full textA dynamically relaxed dense cluster comprised of about 40 stars (the so-called S-stars) inhabits the central region of our Galaxy. Their stars revolve around the Sgr A∗ massive object. To understand the dynamical evolution of planetary systems in a particular environment like that around Sgr A∗, we carry out direct N-body simulations of planetary systems embedded in the S-star cluster. In this work, we investigate the short-term stability of the planets orbiting around S-stars after their close interactions with the central massive black hole of our Galaxy. We find that planetary systems go through encounters with the supermassive black hole (SMBH) and the nearby stars. We determine the frequency and the strength of planetary systems' encounters with the nearby stars as these encounters remarkably increase for systems assigned to S-stars closer to the SMBH. The SMBH severely destabilizes the planetary systems, though we noted that the small oscillations in the mutual eccentricity and inclination of the planetary system could be caused by the planet-planet coupling and the near-resonance effect between the two planets. We obtain estimates of the fraction of survivor planets (∼ 51 per cent), and find that planets stripped from their hosting star are generally captured on close orbits around Sgr A∗. We notify while gas giants are tidally disrupted, terrestrial planets do not. We estimate that Sgr A∗ flares can be due to the tidal disruption events of starless giant planets
Imparipes dilatatus Mahunka & Zaki 1982
No full text<i>Imparipes dilatatus</i> Mahunka & Zaki, 1982 <p> <b>World distribution</b> – This species was described from Hungary and reported from Ukraine (Khaustov 2008).</p> <p> <b>Material examined</b> – Two females were found in soil sample of Galogah-Damghan forestry road, 36.38° N, 53.49° E, and altitude 1000 m a.s.l., June 12, 2021, coll. M. Davari.</p> <p> <b>Remarks</b> – This species is new for mite fauna of Iran.</p>Published as part of <i>Rahiminejad, Vahid, Hakimitabar, Masoud, Davari, Milad & Yahyapour, Eliye, 2023, Scutacarid mites (Acari: Heterostigmata: Scutacaroidea) of Mazandaran province, northern Iran, pp. 159-163 in Persian Journal of Acarology 13 (1)</i> on page 160, DOI: 10.22073/pja.v13i1.84210, <a href="http://zenodo.org/record/10943170">http://zenodo.org/record/10943170</a>
Ustekinumab for the treatment of psoriatic arthritis: an update
No full textParastoo Davari, Michael S Leo, Faranak Kamangar, Nasim Fazel Department of Dermatology, University of California, Davis, CA, USA Abstract: Psoriatic arthritis occurs in 30% of psoriasis patients, and the treatment can be challenging in some patients. Recently, the US Food and Drug Administration approved ustekinumab, a fully human monoclonal antibody, for the management of psoriatic arthritis. In this article, we review large-scale randomized clinical trials addressing the efficacy and safety profile of ustekinumab for the treatment of psoriatic arthritis. Keywords: psoriatic arthritis, psoriasis, ustekinumab 
Advanced sustainable floating photocatalysts for wastewater remediation
No full textWater is one of Earth’s most important molecules: it is essential for life in our world. Climate change is reshaping water access by causing both droughts and floods: there is not enough water, and the amount that is available is usually tainted with some level of pollutants [1]. In this drastic scenario, treating wastewater contaminated by different pollutants is of crucial environmental and commercial importance and urgently requires fast and highly efficient solutions. Heterogeneous photocatalysis has emerged as an interesting strategy for its ability to degrade mixtures of pollutants without the addition of chemical oxidants under mild conditions [2]. However, photocatalytic processes are less effective when used to treat trace concentrations of pollutants in a large volume of contaminated matrices due to the large reactor sizes, the limited light penetration, the high energy cost, and the difficulties in recycling/reusing the photocatalysts. To facilitate the degradation of pollutants traces, different composites have been studied [3]. However, they are nano-sized materials that, although common, raises concerns about nanotoxicity. The ideal photocatalyst should possess activity, selectivity, stability, non-toxicity, cheapness, and easy handling. Achieving all these requirements is a difficult task.
Herein, we present our results related to the development of sustainable photoactive materials obtained by immobilizing innovative adsorptive photocatalysts (i.e., bismuth oxyhalides), on eco-friendly floating supports (e.g., alginate spheres, and Lightweight Expanded Clay Aggregate, LECA). Their obtained performances in the degradation of different pollutants (e.g., dyes, drugs, polyphenols) after exposure to solar light irradiation will be illustrated. A targeted study of the role of water matrix (ultrapure or simulated drinking water), catalyst dosage, type of floating support and recycling tests, approaching the actual application, will be presented with the aim to provide an insight on potential and limitations of each floating device selected for the real application. The promising results obtained open the view toward the future real use of these innovative systems, acting as a bridge between environmental remediation and water reuse.
[1] https://www.who.int/news-room/fact-sheets/detail/drinking-water.
[2] Djellabi, R. et al., Curr. Opin. Chem. Eng., 2021, 1, 100696.
[3] Galloni, M.G. et al., Catalysts 2022, 12(8), 923
Scutacarus (Scutacarus) echidna Soil
No full text<i>Scutacarus</i> (<i>Scutacarus</i>) <i>echidna</i> (Berlese, 1905) <p> <b>World distribution</b> – Previously, this species was recorded from Italy, Germany, Greece, Hungary, France, Russia, Korea and Ukraine (Khaustov 2008).</p> <p> <b>Material examined</b> – Four females were extracted from soil samples and forest litter under old trees of Galogah-Damghan forestry road, 36.08° N, 53.48° E, and altitude 1000 m a.s.l., June 12, 2021, coll. M. Davari.</p> <p> <b>Remarks</b> – This species is new for mite fauna of Iran.</p>Published as part of <i>Rahiminejad, Vahid, Hakimitabar, Masoud, Davari, Milad & Yahyapour, Eliye, 2023, Scutacarid mites (Acari: Heterostigmata: Scutacaroidea) of Mazandaran province, northern Iran, pp. 159-163 in Persian Journal of Acarology 13 (1)</i> on page 160, DOI: 10.22073/pja.v13i1.84210, <a href="http://zenodo.org/record/10943170">http://zenodo.org/record/10943170</a>
Theoretical and experimental studies on the structure-antioxidant activity relationship of synthetic 4-methylcoumarins
No full textThe development of antioxidants as useful drugs for the treatment of neurodegenerative diseases such as Alzheimer's is
extremely challenging in medicinal chemistry. Coumarins have attracted great attention as possible therapeutic tools against
oxygen radicals in human degenerative diseases. In order to establish the possible structure-antioxidant activity relationship, a
series of twenty four 4-methylcoumarin derivatives were examined by employing reducing power measurements, and comparison
with bond dissociation enthalpy and ionization potential calculations. Based on the reducing potency of 4-methylcoumarin
derivatives with respect to trolox, these compounds were classified into five groups as “most active”, “more active”, “moderately
active”, “less active” and “inactive” derivatives. The presence of hydroxyl groups is an essential requirement for the activity, and
substitution of hydroxyl groups by methoxy groups leads to non-active derivatives. The results revealed that dihydroxyl groups in
the ortho position show a better antioxidant activity with respect to dihydroxyl groups in the meta position. This is ascribed to the
ability to construct more stable 4-methylcoumarin radical intermediates by rearrangement of intra-molecular hydrogen bonding.
Our findings indicate that other important factors to enhance the antioxidant activity of coumarins are the number of hydroxyl
groups, the presence of ester substitutions and a thiono functional group on the pyrone ring. However, bond dissociation enthalpy
and ionization potential calculations alone are not sufficient to identify the best antioxidant structures. As a result, chemical and
functional properties of molecules such as 4-methylcoumarins should be examined as a whole entity, considering all substitutions
versus a single substitution to design functional compounds with good antioxidant activity
Theoretical and experimental studies on the structure-antioxidant activity relationship of synthetic 4-methylcoumarins
No full textThe development of antioxidants as useful drugs for the treatment of neurodegenerative diseases such as Alzheimer's is extremely challenging in medicinal chemistry. Coumarins have attracted great attention as possible therapeutic tools against oxygen radicals in human degenerative diseases. In order to establish the possible structure-antioxidant activity relationship, a series of twenty four 4-methylcoumarin derivatives were examined by employing reducing power measurements, and comparison with bond dissociation enthalpy and ionization potential calculations. Based on the reducing potency of 4-methylcoumarin derivatives with respect to trolox, these compounds were classified into five groups as "most active", "more active", "moderately active", "less active" and "inactive" derivatives. The presence of hydroxyl groups is an essential requirement for the activity, and substitution of hydroxyl groups by methoxy groups leads to non-active derivatives. The results revealed that dihydroxyl groups in the ortho position show a better antioxidant activity with respect to dihydroxyl groups in the meta position. This is ascribed to the ability to construct more stable 4-methylcoumarin radical intermediates by rearrangement of intra-molecular hydrogen bonding. Our findings indicate that other important factors to enhance the antioxidant activity of coumarins are the number of hydroxyl groups, the presence of ester substitutions and a thiono functional group on the pyrone ring. However, bond dissociation enthalpy and ionization potential calculations alone are not sufficient to identify the best antioxidant structures. As a result, chemical and functional properties of molecules such as 4-methylcoumarins should be examined as a whole entity, considering all substitutions versus a single substitution to design functional compounds with good antioxidant activity
Sunlight-driven degradation of non-steroidal anti-inflammatory drugs by innovative floating photocatalysts
No full textAmong the most well-known pharmaceuticals, non-steroidal anti-inflammatory drugs (NSAIDs) are characterized by a broad scope of properties widely used in human and veterinary medicine.
Because of the growth and aging of the world population, high consumption of NSAIDs has been recorded in the last few years. Consequently, an increase in concentrations of pharmaceuticals in surface waters is on the rise, also due to the low removal efficiency of wastewater treatment plants. Although these drugs have been known for a long time, some information about them is still limited, such as their presence in water bodies, distribution, and eco-toxicological effects.
The traditional wastewater treatment plants have not been effective and efficient enough to remove these pharmaceuticals. To overcome this limitation, new routes are being evaluated for their efficiency in removing these pollutants. Advanced oxidation processes (AOPs) can successfully remove pharmaceuticals from wastewater. Among all the possible exploitable strategies in this field, heterogeneous photocatalysis has emerged as an interesting strategy, operating under mild conditions and degrading many pollutants without adding chemical oxidants. Although TiO2 is still the most used semiconductor due to its chemical and physical stability, good photoactivity, and low cost, researchers are willing to replace it with new smart materials because of its limited activity under solar light and low thermal stability. Moreover, new floating substrates were employed to immobilize photocatalysts to overcome problems related to the use of slurry systems for water purification. Since their closeness to the water surface, these devices can be fully irradiated by the light source, better oxygenated, and easily recovered and reused. Herein, we present our recent results in the NSAIDs degradation under solar light irradiation by innovative visible active photocatalysts (g-C3N4, BiOX) immobilized on natural floating materials (Lightweight Expanded Clay Aggregate (LECA), alginates’ spheres)
Floating photocatalysts for a sustainable environmental remediation exploiting sunlight
No full textThe chemical industry of the forthcoming years will be shaped by a number of emerging global megatrends strictly related to the demand of innovative materials able to solve new needs in different fields. Among them, environmental deterioration and the scarcity of freshwater have become imperative global issues to be solved nowadays. About 2.4 billion people are exposed to diseases caused by inadequate water sanitation. Additionally, a variety of organic and inorganic compounds, which arise either from anthropic activities or naturally, also contaminates drinking water lowering its quality.
In the last three decades, many efforts have been addressed to develop photoactive materials which could be suitable for real-world use in the field of water remediation. In this regard, water-floating photocatalysts could represent good alternatives to traditional materials thanks to their characteristics in terms of efficiency and reasonability including high oxygenation of the photocatalyst surface, fully solar irradiation, easy recovery and reuse
Thanks to its high photocatalytic activity and good stability TiO2 has been proved to be an excellent photocatalyst. However, because of its wide bandgap (3.2 eV) its efficiency under solar light is dramatically limited. Hence, much effort has been devoted to improving the utilization of solar light by extending the photoresponse of TiO2 to the visible region. In this regard, conducting polymers (CPs), such as polyaniline (PANI) and polypyrrole (PPy), represent promising sensitizers to extend the spectral response of TiO2 to visible light. On the basis of our experience in the field of CPs preparation by innovative green approaches and in the advanced oxidation technologies,
in the present talk, very recent results will be exposed on the use of CPs-modified TiO2 3D materials floating on the water surface and fully exploiting solar irradiation. In these very preliminary tests, the degradation of two classes of pollutants has been investigated and the best materials were subjected to recycle tests in order to demonstrate their stability under the reaction conditions
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