Aluminum Borate Nanowires from the Pyrolysis of Polyaminoborane Precursors

Polyaminoboranes [N(R)H-BH2]n (1: R = H, 2: R = Me) were pyrolyzed on a range of substrates: silicon, metal foils (stainless steel, nickel, and rhodium), and sapphire wafers, as well as on Al2O3 and AlN powders.</p

Magnetic reconnection near the planet as a possible driver of Jupiter's mysterious polar auroras

Auroral emissions have been extensively observed at the Earth, Jupiter, and Saturn. These planets all have appreciable atmospheres and strong magnetic fields, and their auroras predominantly originate from a region encircling each magnetic pole. However, Jupiter’s auroras poleward of these “main” emissions are brighter and more dynamic, and the drivers responsible for much of these mysterious polar auroras have eluded identification to date. We propose that part of the solution may stem from Jupiter’s stronger magnetic field. We model large-scale Alfvénic perturbations propagating through the polar magnetosphere towards Jupiter, showing that the resulting <0.1° deflections of the magnetic field closest to the planet could trigger magnetic reconnection as near as ∼0.2 Jupiter radii above the cloud tops. At Earth and Saturn this physics should be negligible, but reconnection electric field strengths above Jupiter’s poles can approach ∼1 V m-1, typical of the solar corona. We suggest this near-planet reconnection could generate beams of high-energy electrons capable of explaining some of Jupiter’s polar auroras

Mid-infrared sources in the ELAIS Deep X-ray Survey

We present a cross‐correlation of the European Large Area Infrared Space Observatory (ISO) survey (ELAIS) with the ELAIS Deep X‐ray Survey of the N1 and N2 fields. There are seven Chandra point sources with matches in the ELAIS Final Analysis 15‐μm catalogue, out of a total of 28 extragalactic ISO sources present in the Chandra fields. Five of these are consistent with active galactic nuclei (AGN) giving an AGN fraction of ∼19 per cent in the 15‐μm flux range 0.8–6 mJy. We have co‐added the hard X‐ray fluxes of the individually undetected ISO sources and find a low significance detection consistent with star formation in the remaining population. We combine our point source cross‐correlation fraction with the XMM–Newton observations of the Lockman Hole and Chandra observations of the Hubble Deep Field North to constrain source count models of the mid‐infrared galaxy population. The low dust‐enshrouded AGN fraction in ELAIS implied by the number of cross‐identifications between the ELAIS mid‐infrared sample and the Chandra point sources is encouraging for the use of mid‐infrared surveys to constrain the cosmic star formation history, provided there are not further large undetected populations of Compton‐thick AGN

The role of pH on the thermodynamics and kinetics of muscle biochemistry: An in vivo study by 31P-MRS in patients with myo-phosphorylase deficiency

AbstractIn this study we assessed ΔG′ATP hydrolysis, cytosolic [ADP], and the rate of phosphocreatine recovery using Phosphorus Magnetic Resonance Spectroscopy in the calf muscle of a group of patients affected by glycogen myo-phosphorylase deficiency (McArdle disease). The goal was to ascertain whether and to what extent the deficit of the glycogenolytic pathway would affect the muscle energy balance. A typical feature of this pathology is the lack of intracellular acidosis. Therefore we posed the question of whether, in the absence of pH decrease, the rate of phosphocreatine recovery depends on the amount of phosphocreatine consumed during exercise. Results showed that at the end of exercise both [ADP] and ΔG′ATP of patients were significantly higher than those of matched control groups reaching comparable levels of phosphocreatine concentration. Furthermore, in these patients we found that the rate of phosphocreatine recovery is not influenced by the amount of phosphocreatine consumed during exercise. These outcomes provide experimental evidence that: i) the intracellular acidification occurring in exercising skeletal muscle is a protective factor for the energy consumption; and ii) the influence of pH on the phosphocreatine recovery rate is at least in part related to the kinetic mechanisms of mitochondrial creatine kinase enzyme

The ELAIS Deep X-ray Survey

We present initial follow-up results of the ELAIS Deep X-ray Survey which is being undertaken with the Chandra and XMM-Newton Observatories. 235 X-ray sources are detected in our two 75 ks ACIS-I observations in the well-studied ELAIS N1 and N2 areas. 90% of the X-ray sources are identified optically to R=26 with a median magnitude of R=24. We show that objects which are unresolved optically (i.e. quasars) follow a correlation between their optical and X-ray fluxes, whereas galaxies do not. We also find that the quasars with fainter optical counterparts have harder X-ray spectra, consistent with absorption at both wavebands. Initial spectroscopic follow-up has revealed a large fraction of high-luminosity Type 2 quasars. The prospects for studying the evolution of the host galaxies of X-ray selected Type 2 AGN are considered.Comment: 9 pages, 5 figures, To appear in Proceedings of XXI Moriond Conference: "Galaxy Clusters and the High Redshift Universe Observed in X-rays", edited by D. Neumann, F.Durret, & J. Tran Thanh Va

The ELAIS deep X-ray survey - I. Chandra source catalogue and first results

We present an analysis of two deep (75 ks) Chandra observations of the European Large Area Infrared Space Observatory (ISO) Survey (ELAIS) fields N1 and N2 as the first results from the ELAIS deep X-ray survey. This survey is being conducted in well-studied regions with extensive multiwavelength coverage. Here we present the Chandra source catalogues along with an analysis of source counts, hardness ratios and optical classifications. A total of 233 X-ray point sources are detected in addition to two soft extended sources, which are found to be associated with galaxy clusters. An overdensity of sources is found in N1 with 30 per cent more sources than N2, which we attribute to large-scale structure. A similar variance is seen between other deep Chandra surveys. The source count statistics reveal an increasing fraction of hard sources at fainter fluxes. The number of galaxy-like counterparts also increases dramatically towards fainter fluxes, consistent with the emergence of a large population of obscured sources

Dynamics of sediment flux to a bathyal continental margin section through the Paleocene–Eocene Thermal Maximum

The response of the Earth system to greenhouse-gas-driven warming is of critical importance for the future trajectory of our planetary environment. Hyperthermal events – past climate transients with global-scale warming significantly above background climate variability – can provide insights into the nature and magnitude of these responses. The largest hyperthermal of the Cenozoic was the Paleocene–Eocene Thermal Maximum (PETM ∼ 56 Ma). Here we present new high-resolution bulk sediment stable isotope and major element data for the classic PETM section at Zumaia, Spain. With these data we provide a new detailed stratigraphic correlation to other key deep-ocean and terrestrial PETM reference sections. With this new correlation and age model we are able to demonstrate that detrital sediment accumulation rates within the Zumaia continental margin section increased more than 4-fold during the PETM, representing a radical change in regional hydrology that drove dramatic increases in terrestrial-to-marine sediment flux. Most remarkable is that detrital accumulation rates remain high throughout the body of the PETM, and even reach peak values during the recovery phase of the characteristic PETM carbon isotope excursion (CIE). Using a series of Earth system model inversions, driven by the new Zumaia carbon isotope record, we demonstrate that the silicate weathering feedback alone is insufficient to recover the PETM CIE, and that active organic carbon burial is required to match the observed dynamics of the CIE. Further, we demonstrate that the period of maximum organic carbon sequestration coincides with the peak in detrital accumulation rates observed at Zumaia. Based on these results, we hypothesise that orbital-scale variations in subtropical hydro-climates, and their subsequent impact on sediment dynamics, may contribute to the rapid climate and CIE recovery from peak-PETM conditions