The mass function of hydrogen-rich white dwarfs: robust observational evidence for a distinctive high-mass excess near 1Msun

The mass function of hydrogen-rich atmosphere white dwarfs has been frequently found to reveal a distinctive high-mass excess near 1Msun. However, a significant excess of massive white dwarfs has not been detected in the mass function of the largest white dwarf catalogue to date from the Sloan Digital Sky Survey. Hence, whether a high-mass excess exists or not has remained an open question. In this work we build the mass function of the latest catalogue of data release 10 SDSS hydrogen-rich white dwarfs, including the cool and faint population (i.e. effective temperatures 6,000 <~ Teff <~ 12,000 K, equivalent to 12 mag <~ Mbol <~ 13 mag). We show that the high-mass excess is clearly present in our mass function, and that it disappears only if the hottest (brightest) white dwarfs (those with Teff >~ 12,000 K, Mbol <~ 12 mag) are considered. This naturally explains why previous SDSS mass functions failed at detecting a significant excess of high-mass white dwarfs. Thus, our results provide additional and robust observational evidence for the existence of a distinctive high-mass excess near 1Msun. We investigate possible origins of this feature and argue that the most plausible scenario that may lead to an observed excess of massive white dwarfs is the merger of the degenerate core of a giant star with a main sequence or a white dwarf companion during or shortly after a common envelope event.Comment: Accepted for publication by MNRA

Cadmium, manganese, nickel and lead contents in surface sediments of the lower Ulla River and its estuary (northwest Spain)

The authors determined the total contents of cadmium, manganese, nickel and lead in 16 surface sediment samples along the last 7 km of the Ulla River and in its estuary. Prior to chemical analysis, the grain-size fractions below 500, 63 and 2 μm were separated. The metal concentrations were analysed in the fraction below 63 μm, and in selected samples from the clay fraction ( 2 μm). The soil samples were digested with a HF + HNO₃ + HCl mixture and the total concentrations of Cd, Mn, Ni and Pb were analysed with the AAS method. The highest contents of metals were found in the riverine sediments, near the town of Padrón, and in the estuary. The enrichment of metals in the sediments was mainly related to the proximity of the industrial sources, and to the fine particles transported and deposited in the sediments. The Ni and Mn contents found are considered very high, at some points reaching values of up to 357 mg kg⁻¹ and 2 110 mg kg⁻¹, respectively. Lead and Cd were mainly found within the range considered as natural background levels in the sediments of the Galician rias, with concentrations of 25-68 mg kg⁻¹ for Pb and 0.01-0.92 mg kg⁻¹ for Cd. The lower part of the Ulla River and its estuary present: l) moderate to high contamination levels of Mn and Ni; 2) moderate Pb pollution levels; and 3) no Cd contamination. The highest concentrations of metals were obtained in the river, near the wastewater discharges, and in the estuary, associated with fine particles.El contenido total de cadmio, manganeso, níquel y plomo se determinó en 16 muestras de sedimentos superficiales a lo largo de los últimos 7 km del río Ulla y en su estuario. Previamente a los análisis químicos, se realizó la separación granulométrica de los sedimentos en las fracciones inferiores a 500, 63 y 2 μm. La concentración de metales se determinó en la fracción inferior a 63 μm y, para algunas muestras, en la fracción arcilla ( 2 μm). La digestión del sedimento se realizó en una mezcla ácida de HF + HNO₃ + HCl y se analizó la concentración total de Cd, Mn, Ni y Pb por espectroscopia de absorción atómica. Los contenidos más altos en metales se encontraron en los sedimentos del río, en las inmediaciones de Padrón y en los del estuario. El enriquecimiento de los sedimentos en metales se ha relacionado con la proximidad a las zonas industriales y con el material fino transportado y depositado en los sedimentos. Se han encontrado contenidos muy altos de Ni y Mn con valores de 357 mg kg⁻¹ y 2 110 mg kg⁻¹, respectivamente. Las concentraciones de Cd y Pb son comparables a los valores establecidos como niveles naturales en los sedimentos de las rías gallegas: 25-68 mg kg⁻¹ para el Pb y 0.01-0.92 mg kg⁻¹ para el Cd. El sedimento de la parte baja del río Ulla y su estuario presentan niveles moderados-altos de contaminación para Mn y Ni, moderados para Pb y nulos para Cd. Las mayores concentraciones de estos metales en el sedimento fueron medidas asociadas con las fracciones finas ( 63 μm): cerca de Padrón, zona de influencia fluvial y, también, aunque con valores más bajos, en la desembocadura del Ulla, zona de influencia marina.Instituto Español de Oceanografí

The g-factor of the 21/2+^{+} state in 91^{91}Nb

The $^{89}$Y($\alpha$, 2n$\gamma$)$^{91}$Nb reaction was used to populate excited states in $^{91}$Nb. The rotation of the angular distribution of the 357 keV gamma-transition from the 21/2$^{+}$ state was measured in an external magnetic field. The IPAD method was used. By applying $\tau$ =(1.33$\pm$ 0.14) ns for the lifetime of the 21/2$^{+}$ state at 3467 keV, the value of the g-factor 1.18 $\pm$ 0.18 was derived

Orbital periods and component masses of three double white dwarfs

The merger of close double white dwarfs (CDWDs) is one of the favourite evolutionary channels for producing Type Ia supernovae (SN Ia). Unfortunately, current theories of the evolution and formation of CDWDs are still poorly constrained and have several serious uncertainties, which affect the predicted SN Ia rates. Moreover, current observational constraints on this evolutionary pathway for SN Ia mainly rely on only 18 double-lined and/or eclipsing CDWDs with measured orbital and stellar parameters for both white dwarfs. In this paper we present the orbital periods and the individual masses of three new double-lined CDWDs, derived using a new method. This method employs mass ratios, the Hα core ratios and spectral model-fitting to constrain the masses of the components of the pair. The three CDWDs are WD0028–474 (Porb=9.350 ± 0.007 hours, M1 = 0.60 ± 0.06 M⊙, M2 = 0.45 ± 0.04 M⊙), HE0410– 1137 (Porb= 12.208 ± 0.008 hours, M1 = 0.51 ± 0.04M⊙, M2 = 0.39 ± 0.03 M⊙) and SDSSJ031813.25–010711.7 (Porb= 45.908 ± 0.006 hours, among the longest period systems, M1 = 0.40 ± 0.05M⊙, M2 = 0.49 ± 0.05M⊙). While the three systems studied here will merge in timescales longer than the Hubble time and are expected to become single massive (& 0.9 M⊙) white dwarfs rather than exploding as SN Ia, increasing the small sample of CDWDs with determined stellar parameters is crucial for a better overall understanding of their evolution

Macro- And micro-nutrient composition and antioxidant activity of Chickpea and Pea Accessions

Epidemiological studies reported an inverse association between the consumption of legumes and the incidence of age-related diseases. This trend could be attributed to the presence of antioxidant compounds, especially phenolic and flavonoid compounds. In this paper, five pea (Pisum sativum L.) and twelve chickpea (Cicer arietinum L.) accessions, having different characteristics and geographical origin, were characterised in terms of antioxidant activity, as well as macro- and micro-nutrient composition. The antioxidant activity has been evaluated using both DPPH (2,2-diphenyl-1-picrylhydra-zyl) and ABTS (2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) radical scavenging capacity assays. Chickpea and pea accessions showed a different behaviour in the presence of these different radicals. Chickpea accessions were characterised by significantly higher DPPH• scavenging activity, while peas showed a significantly higher value of antioxidant activity evaluated using the ABTS assay. Pea accessions had the highest content of total phenolic compounds, Zn, and Cu. A positive correlation was found between some minerals, such as Zn, Cu and P, and the ABTS•+ scavenging activity. Black and brown chickpea accessions showed significantly higher contents of anthocyanins, Mn, Mg, and Ca, which were positively correlated with the antioxidant activity assessed with the DPPH assay. Despite the dataset investigated in our study included a limited number of accessions, it was possible to highlight the influence of the chemical composition on the antioxidant activity due to the high phenotypic diversity found between the accessions, emphasising the importance of selecting the antioxidant activity assay according to the matrix to be evaluated

Self-assembled hydrogel fibers for sensing the multi-compartment intracellular milieu

Targeted delivery of drugs and sensors into cells is an attractive technology with both medical and scientific applications. Existing delivery vehicles are generally limited by the complexity of their design, dependence on active transport, and inability to function within cellular compartments. Here, we developed self-assembled nanofibrous hydrogel fibers using a biologically inert, low-molecular-weight amphiphile. Self-assembled nanofibrous hydrogels offer unique physical/mechanical properties and can easily be loaded with a diverse range of payloads. Unlike commercially available E. coli membrane particles covalently bound to the pH reporting dye pHrodo, pHrodo encapsulated in self-assembled hydrogel-fibers internalizes into macrophages at both physiologic (37°C) and sub-physiologic (4°C) temperatures through an energy-independent, passive process. Unlike dye alone or pHrodo complexed to E. coli, pHrodo-SAFs report pH in both the cytoplasm and phagosomes, as well the nucleus. This new class of materials should be useful for next-generation sensing of the intracellular milieu

MicroRNA expression patterns in canine mammary cancer show significant differences between metastatic and non-metastatic tumours

Background: MicroRNAs may act as oncogenes or tumour suppressor genes, which make these small molecules potential diagnostic/prognostic factors and targets for anticancer therapies. Several common oncogenic microRNAs have been found for canine mammary cancer and human breast cancer. On account of this, large-scale profiling of microRNA expression in canine mammary cancer seems to be important for both dogs and humans. Methods: Expression profiles of 317 microRNAs in 146 canine mammary tumours of different histological type, malignancy grade and clinical history (presence/absence of metastases) and in 25 control samples were evaluated. The profiling was performed using microarrays. Significance Analysis of Microarrays test was applied in the analysis of microarray data (both unsupervised and supervised data analyses were performed). Validation of the obtained results was performed using real-time qPCR. Subsequently, predicted targets for the microRNAs were searched for in miRBase. Results: Results of the unsupervised analysis indicate that the primary factor separating the samples is the metastasis status. Predicted targets for microRNAs differentially expressed in the metastatic vs. non-metastatic group are mostly engaged in cell cycle regulation, cell differentiation and DNA-damage repair. On the other hand, the supervised analysis reveals clusters of differentially expressed microRNAs unique for the tumour type, malignancy grade and metastasis factor. Conclusions: The most significant difference in microRNA expression was observed between the metastatic and non-metastatic group, which suggests a more important role of microRNAs in the metastasis process than in the malignant transformation. Moreover, the differentially expressed microRNAs constitute potential metastasis markers. However, validation of cfa-miR-144, cfa-miR-32 and cfa-miR-374a levels in blood samples did not follow changes observed in the non-metastatic and metastatic tumours. © 2017 The Author(s)