Star formation history of Canis Major OB1 - II. A bimodal X-ray population revealed by XMM-Newton

The Canis Major OB1 Association has an intriguing scenario of star formation, especially in the Canis Major R1 (CMa R1) region traditionally assigned to a reflection nebula, but in reality an ionized region. This work is focused on the young stellar population associated to CMa R1, for which our previous results from ROSAT, optical and near-infrared data had revealed two stellar groups with different ages, suggesting a possible mixing of populations originated from distinct star-formation episodes. The X-ray data allow the detected sources to be characterized according to hardness ratios, light curves and spectra. Estimates of mass and age were obtained from the 2MASS catalogue, and used to define a complete subsample of stellar counterparts, for statistical purposes. A catalogue of 387 XMM-Newton sources is provided, 78% being confirmed as members or probable members of the CMa R1 association. Flares were observed for 13 sources, and the spectra of 21 bright sources could be fitted by a thermal plasma model. Mean values of fits parameters were used to estimate X-ray luminosities. We found a minimum value of log(L$_X$[erg/s]) = 29.43, indicating that our sample of low-mass stars (M$_\star$ $\leq$ 0.5 M$_\odot$), being faint X-ray emitters, is incomplete. Among the 250 objects selected as our complete subsample (defining our best sample), 171 are found to the East of the cloud, near Z CMa and dense molecular gas, 50% of them being young ( 10 Myr). The opposite happens to the West, near GU CMa, in areas lacking molecular gas: among 79 objects, 30% are young and 50% are older. These findings confirm that a first episode of distributed star formation occurred in the whole studied region ~10 Myr ago and dispersed the molecular gas, while a second, localized episode (< 5 Myr) took place in the regions where molecular gas is still present.Comment: 38 pages, 21 figures, accepted for A&

Shelf-Ocean material exchange influencing the Atlantic chemical composition off NW Iberian margin since the last glaciation

Rivers are the main conduit of sediment to the shelf. The basin geology, the drainage area and the discharge rate are the major factors that determine their sediment load (Milliman and Syvistski, 1992). Besides suspended particles, dissolved components may also give some information on the eroded crust. Sr isotopes in carbonate shells of biological organisms have been used to study, in the geological record, the influence exerted by the chemical weathering of the continental crust on the seawater composition (Macdougall, 1991). In this work, Sr isotope ratios obtained in tests of foraminifera representing the last 40 ka are presented and discussed in the scope of the palaeogeographical evolution of NW Iberia. This work aims to present and discuss the results of Sr isotope analyses (performed, by TIMS, in the Isotope Geology Laboratory of the University of Aveiro) of tests of two species of foraminifera, from nine samples taken along the OMEX core KC 024-19 (181 cm; 42°08’98’’N, 10°29´96’’W, and 2765m), collected in the Galicia Bank area, off Galicia. Taking into account that Sr contained in the carbonate tests is usually considered as preserving the signature of the contemporaneous seawater, one planktonic species (Globigerina bulloides) and one benthic species (Cibicides wuellerstorfi) were selected in order to try to detect Sr isotope variations both through time and between two different levels of the water column. The core age model, which records the last 40 ka, is based on a combination of oxygen isotope stratigraphy, eight AMS 14C datings and the synchronisation of the last four Heinrich Events in the Iberian Margin sedimentary records. As a whole, the obtained 87Sr/86Sr ratios vary between 0.709209 and 0.709108, with a mean 2σ error of 0.000025. These values lie within the range of modern marine Sr isotope ratios (0.70910-0.70922), as previously defined using analyses of both seawater and marine carbonates (see compilation by Faure and Mensing, 2005). Despite their small variation, the 87Sr/86Sr ratios obtained in G. bulloides seem to indicate that Sr dissolved in seawater at the KC 024-19 core site became slightly less radiogenic after the Last Glacial Maximum (LGM). This decrease is concomitant with diminishing amounts of the detrital components in the sediments (Fig. 1). Therefore, both the composition of dissolved Sr, as revealed by results on tests of planktonic foraminifera, and the proportions of suspended terrigenous particulate material arriving at the KC 024-19 site point to a decreasing importance of the contribution of the erosion of the Iberian Variscan crust since the Last Glacial Maximum and in the Holocene. The 87Sr/86Sr ratios measured in tests of benthic foraminifera (C. wuellerstorfi) are more erratic and no correlation can be established with palaeogeographical/palaeoclimatic constraints. The difference between the behaviour of Sr compositions in G. bulloides and C. wuellerstorfi may indicate that whilst the planktonic foraminifera should reproduce very closely the seawater composition, the benthic organisms should, in addition to the major role of seawater, also be affected by some sort of interaction with the sediments. As such, planktonic foraminifera are probably more reliable indicators of seawater composition in studies involving very small periods and corresponding very slight variations of the 87Sr/86Sr ratios. Taking into account that G. bulloides is a common planktonic species (living mostly in the first 50m of the water column), whose tests seem to be in equilibrium with sea water composition, variations in its 87Sr/86Sr ratios can be related with changes in the chemical composition of the water of the Atlantic Ocean off NW Iberian Margin. The highest 87Sr/86Sr values are contemporaneous with a period of low sea level (about -140 m; Dias et al., 2000) during the LGM. According to Dias et al. (2000) at 18 ka BP the shoreline was close to the shelf break. The summital parts of the Gerês and Estrela mountains were covered by local glaciers and close to the coast freezing occurred frequently. The river catchments, which extended far to the shelf, received more rainfall due to a longer, compared to present day conditions, wet season, which promoted both physical and chemical weathering. Higher pluviosity combined with the effect of spring ice melting maintained high river discharge and consequently caused very important sediment supply to the coastal zone. The extremely narrow shelf was a very energetic environment due to sea bottom inclination and very limited long wave refraction. Therefore, at that time, a long wet season and very competent rivers should have caused important erosion of the Variscan basement in NW Iberia. Additionally, then, the shoreline was much closer to the KC 024-19 site. The combination of all these factors favoured an important deposition of terrigenous sediments and the local slight enrichment in radiogenic Sr of the seawater. With sea level rise, after the deglaciation and during the Holocene, the river estuaries became progressively far away from the shelf break. Their competence of transport also became progressively reduced and the offshore transport of detrital sediments became progressively lower. Conversely the biogenic carbonate proportion in the sediments increased, due to lower dilution by the terrigenous particles. Simultaneously, the values of 87Sr/86Sr in the seawater at the KC 024-19 site became lower, as a consequence of a complete homogenization with the ocean global composition, which was now more effective with the increasing distance towards shoreline

Interafacial tension and surfactant stabilisation during membrane emulsification

A new insight on the interaction between complex fluids and solid surfaces is given in this study. It is demonstrated how these liquid-solid interactions can greatly influence the droplet generation during membrane emulsification and, therefore, resultant emulsion size and uniformity. These aspects of the process are often underestimated and poorly comprehended by, specially, industrial colleagues. Thus, that unawareness can lead to poor results and to a disbelief in this upcoming technology. A novel membrane emulsification system is reported consisting of a tubular metal membrane, periodically azimuthally (tangentially) oscillated with frequencies up to 50 Hz and 7 mm displacement in a gently cross flowing continuous phase. Using an azimuthally oscillating membrane, oil-in-water (o/w) emulsions were experimentally produced with a diameter of 20 120 µm, and a coefficient of variation (CV) of droplet size of 8%. The drop size was correlated with shear stress at the membrane surface using a force balance. In a single pass of continuous phase, it was possible to achieve high dispersed phase concentrations up to 38% v/v. A vertical oscillation membrane emulsification was used to study the influence of dynamic interfacial tension in membrane emulsification: drop size can be tuned between 35 and 85 µm by changing the surfactant concentration in the continuous phase. In addition, a method to determine the percentage of active pores during membrane emulsification is demonstrated. This method links knowledge acquired in the surfactant adsorption dynamics and drop expansion rate. This study reinforces the importance of dynamic interfacial tension which must be considered in process design, and modelling purposes, particularly in two liquid phase systems using membranes such as membrane emulsification at high injection rates. Hydrophobization of metal surfaces is reported based on silanization reactions to broaden the use of metal porous membranes to water-in-oil (w/o) emulsion production. The developed procedure is shown to be a straightforward hydrophobization method, with minimal cost to apply, reproducible, stable and the possibility of reuse of the membrane after losing hydrophobicity by simply reapplying the hydrophobization method. On the other hand, formation of water-based droplets can be achieved using a hydrophilic porous metal membrane. To investigate this, water-based droplets were produced using a hydrophilic membrane and wetting experiments were also carried out: sessile droplets were used to determine static contact angles and a rotating drum system was used to determine contact angles under dynamic conditions. In the latter case the three-phase contact line was observed between the rotating drum and two immiscible liquids. It was observed that the oil phase can preferably wet a hydrophilic surface in case when a surfactant is present in the oil phase, and above a certain concentration, even in the presence of the water phase. Apart from membrane emulsification, spontaneous formation of water droplets in kerosene was observed, facilitated by the presence of an oil soluble surfactant: Span® 80. This process was characterized and the influence of chemical potential between both phases was evaluated. Nano-sizing analyses were performed for a set of experiments, where the influence of the surfactant concentration in the organic phase, as well as the influence of NaCl concentration in the aqueous phase, was studied. Water droplets between 100 and 400 nm were measured in kerosene. Interfacial tension between both phases, was not lower than 4 mN/m. Therefore, ultra-low interfacial tension was not required for this process to occur spontaneously. Continuous production of spherical polymeric particles, via membrane emulsification, was demonstrated. An o/w emulsion was used as precursor and, by solvent removal, solid particles were obtained. In addition, production of polycaprolactone (PCL) particles containing encapsulated (entrapped) protein model was also demonstrated via a double emulsion method

Remoção de metais pesados por biofilmes suportados em carvão activado

Instituto de Biotecnologia e Química Fina (IBQF)

Remoção de metais pesados por biofilmes suportados em carvão activado

Instituto de Biotecnologia e Química Fina (IBQF)

Achondroplasia and Down’s Syndrome – Case Report of a Rare Association

The association of achondroplasia and Down’s syndrome is very rare and only five cases have been reported in the literature so far. These two genetic alterations have overlapping features such as short stature, developmental delay or hypotonia that complicate management and follow up. We report the case of a girl that is unique since she was born from a mother with achondroplasia and a healthy father. Achondroplasia was dominantly inherited from the mother but at birth she had features of Down’s syndrome as well, confirmed later by kariotype. We review her evolution regarding physical health, cognitive problems and adaptive behavior during her eight years of life. To our knowledge this is the first report of the combination of both disorders in which the achondroplasia was inherited and not a “de novo” mutation. We address the problems resulting from the additional burden of having two disorders, and how they can be improved, aiming to help others in the future to deal with these cases

Detection and resolution of normative conflicts in multi-agent systems : a literature survey

Peer reviewedPostprin

Multifaceted CK2 in malignant and healthy T cells

Copyright © Ribeiro et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License 3.0 (CC BY 3.0), which permits unrestricted use, distribution, and re-production in any medium, provided the original author and source are credited.Among kinases that support the survival and turnover of tumor cells, the serine/threonine protein kinase CK2 has been shown to be frequently overexpressed or hyperactivated in solid and hematological malignancies. Our previous work on T-cell acute lymphoblastic leukemia (T-ALL) showed that CK2 maintains leukemia cell viability by phosphorylating and thereby inactivating the tumor suppressor PTEN, which results in hyperactivation of PI3K/AKT signaling. We also demonstrated the potential of using the clinical-grade CK2-specific chemical inhibitor, CX-4945 (Silmitasertib), against primary T-ALL cells. We have now extended these findings to the rare (<10% of all cases) form of T-ALL that derives from the transformation of thymocytes belonging to the γδ T-cell lineage.info:eu-repo/semantics/publishedVersio

Growth performance, biochemical composition and sedimentation velocity of Tetraselmis sp. CTP4 under different salinities using low-cost lab- and pilot-scale systems

Biomass harvesting is one of the most expensive steps of the whole microalgal production pipeline. Therefore, the present work aimed to understand the effect of salinity on the growth performance, biochemical composition and sedimentation velocity of Tetraselmis sp. CTP4, in order to establish an effective low-cost pilot-scale harvesting system for this strain. At lab scale, similar growth performance was obtained in cultures grown at salinities of 5, 10 and 20 g L-1 NaCl. In addition, identical settling velocities (2.4-3.6 cm h-1) were observed on all salinities under study, regardless of the growth stage. However, higher salinities (20 g L-1) promoted a significant increase in lipid contents in this strain compared to when this microalga was cultivated at 5 or 10 g L-1 NaCl. At pilot-scale, cultures were cultivated semi-continuously in 2.5-m3 tubular photobioreactors, fed every four days, and stored in a 1-m3 harvesting tank. Upon a 24-hour settling step, natural sedimentation of the microalgal cells resulted in the removal of 93% of the culture medium in the form of a clear liquid containing only vestigial amounts of biomass (0.07 ± 0.02 g L-1 dry weight; DW). The remaining culture was recovered as a highly concentrated culture (19.53 ± 4.83 g L-1 DW) and wet microalgal paste (272.7 ± 18.5 g L-1 DW). Overall, this method provided an effective recovery of 97% of the total biomass, decreasing significantly the harvesting costs.Agência financiadora Portuguese national budget P2020 Foundation for Science and Technology (FCT) CMAR/Multi/04326/2013 ALGARED+ 1398 EP - INTERREG V-A Espana Portugal project ALGACO2 project 023310 COST Action 1408 - European Network for Bio-products FCT SFRH/BD/105541/2014info:eu-repo/semantics/publishedVersio