The Friedel oscillations in the presence of transport currents

We investigate the Friedel oscillations in a nanowire coupled to two macroscopic electrodes of different potentials. We show that the wave-length of the density oscillations monotonically increases with the bias voltage, whereas the amplitude and the spatial decay exponent of the oscillations remain intact. Using the nonequilibrium Keldysh Green functions, we derive an explicit formula that describes voltage dependence of the wave-length of the Friedel oscillations.Comment: 5 pages, 3 figures, RevTe

The Effect of Co Incorporation on the CO Oxidation Activity of LaFe1−xCoxO3 Perovskites

Perovskite oxides are versatile materials due to their wide variety of compositions of- fering promising catalytic properties, especially in oxidation reactions. In the presented study, LaFe1−xCoxO3 perovskites were synthesized by hydroxycarbonate precursor co-precipitation and thermal decomposition thereof. Precursor and calcined materials were studied by scanning electron microscopy (SEM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TG), and X-ray powder diffraction (XRD). The calcined catalysts were in addition studied by transmission electron microscopy (TEM) and N2 physisorption. The obtained perovskites were applied as catalysts in transient CO oxidation, and in operando studies of CO oxidation in diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). A pronounced increase in activity was already observed by incorporating 5% cobalt into the structure, which contin- ued, though not linearly, at higher loadings. This could be most likely due to the enhanced redox properties as inferred by H2-temperature programmed reduction (H2-TPR). Catalysts with higher Co contents showing higher activities suffered less from surface deactivation related to carbonate poisoning. Despite the similarity in the crystalline structures upon Co incorporation, we observed a different promotion or suppression of various carbonate-related bands, which could indicate different surface properties of the catalysts, subsequently resulting in the observed non-linear CO oxidation activity trend at higher Co contents

Dynamics of Reactive Oxygen Species on Cobalt-Containing Spinel Oxides in Cyclic CO Oxidation

Reactive oxygen species (ROS) are considered to be responsible for the high catalytic activity of transition metal oxides like Co3-xFexO4 in oxidation reactions, but the detailed influences of catalyst composition and morphology on the formation of these reactive oxygen species are not fully understood. In the presented study, Co3O4 spinels of different mesostructures, i.e., particle size, crystallinity, and specific surface area, are characterized by powder X-ray diffraction, scanning electron microscopy, and physisorption. The materials were tested in CO oxidation performed in consecutive runs and compared to a Co3-xFexO4 composition series with a similar mesostructure to study the effects of catalyst morphology and composition on ROS formation. In the first run, the CO conversion was observed to be dominated by the exposed surface area for the pure Co-spinels, while a negative effect of Fe content in the spinels was seen. In the following oxidation run, a U-shaped conversion curve was observed for materials with high surface area, which indicated the in situ formation of ROS on those materials that were responsible for the new activity at low temperature. This activation was not stable at the higher reaction temperature but was confirmed after temperature-programmed oxidation (TPO). However, no activation after the first run was observed for low-surface-area and highly crystalline materials, and the lowest surface-area material was not even activated after TPO. Among the catalyst series studied here, a correlation of small particle size and large surface area with the ability for ROS formation is presented, and the benefit of a nanoscaled catalyst is discussed. Despite the generally negative effect of Fe, the highest relative activation was observed at intermediate Fe contents suggesting that Fe may be involved in ROS formation

ERS/EACTS statement on the management of malignant pleural effusions

Malignant pleural effusions (MPE) are a common pathology, treated by respiratory physicians and thoracic surgeons alike. In recent years, several well-designed randomized clinical trials have been published that have changed the landscape of MPE management. The European Respiratory Society (ERS) and the European Association for Cardio-Thoracic Surgery (EACTS) established a multidisciplinary collaboration of clinicians with expertise in the management of MPE with the aim of producing a comprehensive review of the scientific literature. Six areas of interest were identified, including the optimum management of symptomatic MPE, management of trapped lung in MPE, management of loculated MPE, prognostic factors in MPE, whether there is a role for oncological therapies prior to intervention for MPE and whether a histological diagnosis is always required in MPE. The literature revealed that talc pleurodesis and indwelling pleural catheters effectively manage the symptoms of MPE. There was limited evidence regarding the management of trapped lung or loculated MPE. The LENT score was identified as a validated tool for predicting survival in MPE, with Brims' prognostic score demonstrating utility in mesothelioma prognostication. There was no evidence to support the use of oncological therapies as an alternative to MPE drainage, and the literature supported the use of tissue biopsy as the gold standard for diagnosis and treatment planning.Management options for malignant pleural effusions have advanced over the past decade, with high-quality randomized trial evidence informing practice in many areas. However, uncertainties remain and further research is required http://ow.ly/rNt730jOxOS

Dynamics of nest occupation and homing of solitary bees in painted trap nests

1. The oil‐collecting bee Centris analis (Fabricius, 1804) is an important pollinator for the Neotropical region. The species can be attracted to nest in human‐made cavities. Such trap nests or insect hotels offer the opportunity to study the behaviour of populations in semifield conditions. 2. We studied a newly established trap nest aggregation of C. analis in Mato Grosso do Sul, Brazil and tested the effect that differentially painted nesting options have on the rate of nest foundation, and on the ability of relocating the nest when returning from a foraging trip (homing behaviour). Moreover, we tested if the duration of foraging trips decreased with time. 3. We found that females preferred to nest in painted nests compared to unpainted nests, with blue nests being the most occupied ones, followed by purple, yellow, white, and green. Furthermore, bees improved their homing behaviour with time, however, nest colour did not seem to have an effect on this process. Moreover, we found that bees reduce the duration of their foraging trips with time. This could be an indicator of improved foraging efficiency through learning. 4. These findings could inform a new and fruitful line of research on the behaviour and ecology of trap nesting solitary bees

ATR/Mec1: coordinating fork stability and repair.

During S phase, eukaryotic cells unwind and duplicate a tremendous amount of DNA, generating structures that are very sensitive to both endogenous and exogenous insults. The collision of DNA polymerases with damaged DNA or other obstructions to fork progression generates replication stress, which can evolve into fork collapse if the replisome components are not stabilized. To ensure genome integrity, stalled replication forks are recognized by a checkpoint, whose central player is the human kinase ATR or Mec1 in S. cerevisiae. This review will discuss recent findings revealing roles of the ATR/Mec1 kinase: both in stabilizing the replisome directly and in activating the checkpoint response to regulate origin firing, DNA repair, fork restart, and cell cycle progression

Disentangling the path of pollinator attraction in temporarily colored flowers

Plants may use different strategies to attract pollinators in long distance (e.g. floral display) and in short distance (e.g. ratio between differentially colored flowers) scales. The Verbenaceae Lantana canescens Kunth is a wide spread species in open sites of the Brazilian Pantanal wetland. Individuals of this generalist species can produce a variable number of open inflorescences with yellow and white flowers that are organized in whorls. In this study we tested the hypothesis that increased floral display (long distance attraction) and the ratio between yellow and white flowers (short distance attraction) enhances the number of pollinator species and individuals. We observed flower visitors and calculated floral parameters in 38 plots of 1 m2 each, that contained a varying number of flowering L. canescens individuals. Non-metric multidimensional scaling and Bray-Curtis distances were used to account for flower visitor composition and the relative visitation rate, respectively. We used a structural equation model to test the power of each predictor variable on the visitation rate and a covariance analysis to disentangle the effect of each independent variable on the frequency of plant-pollinator interactions. We found that the number of flower visitors and the visitation rate increased with increasing number of inflorescences. Disentangling long and short distance attraction indicated that the number of inflorescences (per plot) and the number of yellow flowers (yellowing effect) contributed most to flower visitation at long and short distance, respectively