We have used the MOST (Microvariability and Oscillations of STars) microsatellite to obtain four weeks of contiguous high-precision broad-band visual photometry of the O7.5III(n)((f)) star ξ Persei ...in 2011 November. This star is well known from previous work to show prominent DACs (discrete absorption components) on time-scales of about 2 d from UV spectroscopy and non-radial pulsation with one (l = 3) p-mode oscillation with a period of 3.5 h from optical spectroscopy. Our MOST-orbit (101.4 min) binned photometry fails to reveal any periodic light variations above the 0.1 mmag 3σ noise level for periods of a few hours, while several prominent Fourier peaks emerge at the 1 mmag level in the two-day period range. These longer period variations are unlikely due to pulsations, including gravity modes. From our simulations based upon a simple spot model, we deduce that we are seeing the photometric modulation of several corotating bright spots on the stellar surface. In our model, the starting times (random) and lifetimes (up to several rotations) vary from one spot to another yet all spots rotate at the same period of 4.18 d, the best-estimated rotation period of the star. This is the first convincing reported case of corotating bright spots on an O star, with important implications for drivers of the DACs (resulting from corotating interaction regions) with possible bright-spot generation via a breakout at the surface of a global magnetic field generated by a subsurface convection zone.
We have used the MOST (Microvariability and Oscillations of STars) microsatellite to obtain four weeks of contiguous high-precision broad-band visual photometry of the O7.5III(n)((f)) star ... Persei ...in 2011 November. This star is well known from previous work to show prominent DACs (discrete absorption components) on time-scales of about 2 d from UV spectroscopy and non-radial pulsation with one (l = 3) p-mode oscillation with a period of 3.5 h from optical spectroscopy. Our MOST-orbit (101.4 min) binned photometry fails to reveal any periodic light variations above the 0.1 mmag 3... noise level for periods of a few hours, while several prominent Fourier peaks emerge at the 1 mmag level in the two-day period range. These longer period variations are unlikely due to pulsations, including gravity modes. From our simulations based upon a simple spot model, we deduce that we are seeing the photometric modulation of several corotating bright spots on the stellar surface. In our model, the starting times (random) and lifetimes (up to several rotations) vary from one spot to another yet all spots rotate at the same period of 4.18 d, the best-estimated rotation period of the star. This is the first convincing reported case of corotating bright spots on an O star, with important implications for drivers of the DACs (resulting from corotating interaction regions) with possible bright-spot generation via a breakout at the surface of a global magnetic field generated by a subsurface convection zone. (ProQuest: ... denotes formulae/symbols omitted.)
Nous savons que la grande majorité des étoiles WC9 produit de la poussière à base
de carbone. Cette dernière doit se former dans des zones de très haute densité afin de
survivre à l’environnement ...hostile qu’est celui du vent d’une étoile WR. Les étoiles WC
appartenant à un système binaire WR + O produisent de la poussière quand les vents
des deux étoiles entrent en collision et forment une zone de choc pouvant augmenter
la densité du gaz d’un facteur 1000. Par contre, plusieurs étoiles WC9 n’ont, à ce jour,
montré aucun signe de la présence d’un compagnon. Le but du projet est de tenter d’identifier
un mécanisme alternatif responsable de la formation de poussière dans les étoiles
WC9 n’appartenant pas à un système binaire. Nous présentons les résultats d’une campagne
d’observation visant à caractériser la variabilité spectroscopique d’un échantillon
de huit étoiles WC9 et une étoile WC8d. Nos résultats indiquent que la majorité des
étoiles montrent des variations à grande échelle dans la raie d’émission C III 5696, soit
à un niveau d’au moins 5% du flux de la raie et que les structures dans le vent ont une
dispersion de vitesses de l’ordre de 150-300 km/s. De manière générale, les variations
de vitesse radiales sont anti-corrélées avec le coefficient d’asymétrie de la raie, ce
qui semble infirmer la présence d’un compagnon. Des observations en photométrie de
l’étoile WR103 montrent une période de 9.1 ± 0.6 jours qui s’accorde avec les variations
spectroscopiques et qui ne semble pas, de manière évidente, d’origine binaire.
We know that the majority of WC9 stars produces carbon-based dust. To survive in
the hot and harsh environement that is the wind of a WR star, the dust grains must be
formed in regions of very high density. We know that WC stars that are part of a WR
+ O system can produce dust at periastron passage where the collision of the two stellar
winds is strong enough to produce shocks that compress the gas to densities up to a factor
103 higher than that of the WR star. However, so far, many WC9 stars have shown no
signs of a companion. The goal of the current project is to identify a mechanism that
could be responsible for the formation of dust in single WC9 stars. We present the results
of an observing campaign which aimed to characterize the spectroscopic variability of
eight WC9 stars and one WC8d star. Our results indicate that most stars show large
scale variations of their C III 5696 emission line that reach at least 5% of the total line
flux, and that the structures in the wind have a mean velocity dispersion of 150-300
km/s. In general, the radial velocity variations are anti-correlated with the skewness
variations. This seems to indicate that the variations are not due to the presence of a
companion. Photometric observations of WR 103 show a period of 9.1 ± 0.6 days that
agrees with the spectroscopic variations and does not seem from binary origin.
We have used the MOST (Microvariability and Oscillations of STars) microsatellite to obtain four weeks of contiguous high-precision broadband visual photometry of the O7.5III(n)((f)) star {\xi} ...Persei in November 2011. This star is well known from previous work to show prominent DACs (Discrete Absorption Components) on time-scales of about 2 d from UV spectroscopy and NRP (Non Radial Pulsation) with one (l = 3) p-mode oscillation with a period of 3.5 h from optical spectroscopy. Our MOST-orbit (101.4 min) binned photometry fails to reveal any periodic light variations above the 0.1 mmag 3-sigma noise level for periods of hours, while several prominent Fourier peaks emerge at the 1 mmag level in the two-day period range. These longer-period variations are unlikely due to pulsations, including gravity modes. From our simulations based upon a simple spot model, we deduce that we are seeing the photometric modulation of several co-rotating bright spots on the stellar surface. In our model, the starting times (random) and lifetimes (up to several rotations) vary from one spot to another yet all spots rotate at the same period of 4.18 d, the best-estimated rotation period of the star. This is the first convincing reported case of co-rotating bright spots on an O star, with important implications for drivers of the DACs (resulting from CIRs - Corotating Interaction Regions) with possible bright-spot generation via a breakout at the surface of a global magnetic field generated by a subsurface convection zone.
CD169
macrophages reside in lymph node (LN) and spleen and play an important role in the immune defense against pathogens. As resident macrophages, they are responsive to environmental cues to shape ...their tissue-specific identity. We have previously shown that LN CD169
macrophages require RANKL for formation of their niche and their differentiation. Here, we demonstrate that they are also dependent on direct lymphotoxin beta (LTβ) receptor (R) signaling. In the absence or the reduced expression of either RANK or LTβR, their differentiation is perturbed, generating myeloid cells expressing SIGN-R1 in LNs. Conditions of combined haploinsufficiencies of RANK and LTβR revealed that both receptors contribute equally to LN CD169
macrophage differentiation. In the spleen, the
-directed ablation of either receptor results in a selective loss of marginal metallophilic macrophages (MMMs). Using a RANKL reporter mouse, we identify splenic marginal zone stromal cells as a source of RANKL and demonstrate that it participates in MMM differentiation. The loss of MMMs had no effect on the splenic B cell compartments but compromised viral capture and the expansion of virus-specific CD8
T cells. Taken together, the data provide evidence that CD169
macrophage differentiation in LN and spleen requires dual signals from LTβR and RANK with implications for the immune response.
HiPco single-walled carbon nanotube samples contain a non-negligible amount (about 30wt.%) of metal-based impurities. These impurities are prejudicial to the development of CNT-based applications. In ...the literature, there is no agreement for their nature and their relative content. Consequently, the standard purification treatments could not be selective enough and they lead to damage the carbon nanotubes. In this work, we have deeply investigated the mineral impurities of a raw HiPco SWCNT sample by means of several techniques. We were able to identify and quantify at least six iron-based phases that coexist in the HiPco SWCNT samples. The raw SWCNTs were submitted to a selective purification treatment involving a high temperature treatment under chlorine. The results show that the efficiency of the metal removal is improved by increasing the temperature of treatment leading to a purification yield of 95.4%, while preserving the structural quality of the SWCNTs. The analysis of the mineral residues in the purified and annealed SWCNT samples allows to propose the chemical mechanisms involved during the chemical treatments.
This study examines the effect of pretreatment and doping to enhance the ORR activity of multiwalled carbon nanotubes (MWCNTs). Melamine and thio-urea are chosen as precursors for mono and co-doping, ...respectively. A series of samples with pristine and pretreated CNTs are prepared and characterized physicochemically by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) and electrochemically by cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The obtained results show that co-doping is an effective way for improving ORR activity, due to the synergistic effect of N and S for changing the charge and spin density, respectively. Moreover, thio-urea favors the proportion of pyridinic and graphitic nitrogen configurations within doped samples. As a consequence, our synthesis method gives samples with superior ORR activity. The maximum ORR activity is obtained for NS-OX-CNTs which shows an over potential of 0.95 V vs RHE at 0.1 mA/cm
2
, which is comparable to Pt/C (0.98 V vs RHE). The electron transfer number (n) is calculated as 3.9 at 0.4 V which suggests that the ORR proceeds through a dominant 4 e
−
path. These comparable half-cell results to that of Pt/C pave the way for further testing as cathode materials for anion exchange membrane fuel cells (AEMFC).
Graphical abstract
Appropriate training for community pharmacists may improve the quality of medication use. Few studies have reported the impact of such programs on medication management for patients with chronic ...kidney disease (CKD).
Multicenter, cluster-randomized, controlled trial.
Patients with CKD stage 3a, 3b, or 4 from 6 CKD clinics (Quebec, Canada) and their community pharmacies.
Each cluster (a pharmacy and its patients) was randomly assigned to either ProFiL, a training-and-communication network program, or the control group. ProFiL pharmacists completed a 90-minute interactive web-based training program on use of medications in CKD and received a clinical guide, patients’ clinical summaries, and facilitated access to the CKD clinic.
Drug-related problems (primary outcome), pharmacists’ knowledge and clinical skills, and patients’ clinical attributes (eg, blood pressure and glycated hemoglobin concentration).
Drug-related problems were evaluated the year before and after the recruitment of patients using a validated set of significant drug-related problems, the Pharmacotherapy Assessment in Chronic Renal Disease (PAIR) criteria. Pharmacists’ questionnaires were completed at baseline and after 1 year. Clinical attributes were documented at baseline and after 1 year using available information in medical charts.
207 community pharmacies, 494 pharmacists, and 442 patients with CKD participated. After 1 year, the mean number of drug-related problems per patient decreased from 2.16 to 1.60 and from 1.70 to 1.62 in the ProFiL and control groups, respectively. The difference in reduction of drug-related problems per patient between the ProFiL and control groups was −0.32 (95% CI, −0.63 to −0.01). Improvements in knowledge (difference, 4.5%; 95% CI, 1.6%-7.4%) and clinical competencies (difference, 7.4%; 95% CI, 3.5%-11.3%) were observed among ProFiL pharmacists. No significant differences in clinical attributes were observed across the groups.
High proportion of missing data on knowledge and clinical skills questionnaire (34.6%) and clinical attributes (11.1%).
Providing community pharmacists with essential clinical data, appropriate training, and support from hospital pharmacists with expertise in nephrology increases pharmacists’ knowledge and reduces drug-related problems in patients with CKD who are followed up in clinics incorporating a multidisciplinary health care team.
Functionalization on the carbon material of PEM fuel cells providing them an ionic conductivity, has been thought as a promising way to improve the catalyst activity. Pt/Vulcan catalysts grafted with ...polystyrene sulfonate (PSSA) groups from 5 to 20wt.% have been prepared. Owing to the ion-exchange properties of the PSSA grafted on carbon support, we developed less-Nafion electrodes, with only 0.25 or 0.50mgcm−2 Nafion loading. The effect of PSSA graft ratio and the Nafion amount was studied in a single cell at 30°C by polarization curves and impedance measurements. It was found that 5 and 10wt.% PSSA with 0.50mgcm−2 Nafion allow high efficiency, however lower than 10wt.% grafted Pt/C with 0.25mgcm−2 Nafion only. The performance of the various electrodes could be correlated to the overall amount of sulfonate introduced: highest yields were obtained with an overall sulfonate concentration near 0.7–0.8μmolcm−2.
•Promising use of PSSA-grafted carbon support for PEM fuel cell cathodes•Nafion addition in PEM cathodes could be reduced by 50% by carbon modification.•Electrochemical characterization and resistance of PEM fuel cell with modified carbon
Carbon nanotubes (CNTs) are difficult to process, and their assembly in macroscopic materials that allow us to benefit from the exceptional properties of the nanotubes is of crucial interest for ...applications. The developed CNT processing procedures usually involve additives that remain in the final product and are known to diminish the properties of the CNT-based material. Here, we propose a multistep approach to process single-walled carbon nanotubes (SWNTs) and obtain macroscopic additive-free SWNT materials. High-quality dispersion of purified SWNTs is first induced in polar solvent due to their preceding reduction reaction with an alkali metal. The partial debundling process occurring at this stage leads to ramified SWNTs. They can then be self-assembled by attractive intermolecular forces through a controlled destabilization of the dispersions by a simple oxidation. Swollen gels of SWNTs are formed at an air/solvent interface. After freeze-drying, the additive-free SWNT material shows a hierarchical structure with highly interconnected SWNTs. Thanks to the obtained ramification of the SWNTs, these latter are able to well entangle what guarantees the robustness of the obtained additive-free SWNT material. Moreover, this integrated process offers an increase of the accessible surface compared to that of the raw bundled SWNTs. The obtained assembled SWNTs show an improved adsorption capacity.
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