Beyond Chandra - the X-ray Surveyor

Over the past 16 years, NASA's Chandra X-ray Observatory has provided an unparalleled means for exploring the universe with its half-arcsecond angular resolution. Chandra studies have deepened our understanding of galaxy clusters, active galactic nuclei, galaxies, supernova remnants, planets, and solar system objects addressing almost all areas of current interest in astronomy and astrophysics. As we look beyond Chandra, it is clear that comparable or even better angular resolution with greatly increased photon throughput is essential to address even more demanding science questions, such as the formation and subsequent growth of black hole seeds at very high redshift; the emergence of the first galaxy groups; and details of feedback over a large range of scales from galaxies to galaxy clusters. Recently, NASA Marshall Space Flight Center, together with the Smithsonian Astrophysical Observatory, has initiated a concept study for such a mission named the X-ray Surveyor. This study starts with a baseline payload consisting of a high resolution X-ray telescope and an instrument set which may include an X-ray calorimeter, a wide-field imager and a dispersive grating spectrometer and readout. The telescope would consist of highly nested thin shells, for which a number of technical approaches are currently under development, including adjustable X-ray optics, differential deposition, and modern polishing techniques applied to a variety of substrates. In many areas, the mission requirements would be no more stringent than those of Chandra, and the study takes advantage of similar studies for other large area missions carried out over the past two decades. Initial assessments indicate that such an X-ray mission is scientifically compelling, technically feasible, and worthy of a high rioritization by the next American National Academy of Sciences Decadal Survey for Astronomy and Astrophysics.Comment: 6 pages, 6 figures, paper 9510-01 presented at SPIE Europe, Prague, April 201

Recent respiratory infection and risk of venous thromboembolism: case–control study through a general practice database

Background The association between respiratory infection and risk of heart attacks and strokes is well established. However, less evidence exists for an association between respiratory infection and venous thromboembolism (VTE). In this article, we describe the associations between respiratory infection and VTE

Brood patch and sex-ratio observations indicate breeding provenance and timing in New Zealand storm petrel (Fregetta maoriana)

We used measurements of brood patch and moult status to estimate the breeding phenology of New Zealand Storm-Petrel, using birds caught at sea within the Hauraki Gulf Marine Park near Auckland, New Zealand. Birds caught October–January had completely downy brood patches, whereas birds caught February–April had bare brood patches with an observed male bias in the February sex-ratio, consistent with a female pre-laying exodus typical of petrels and with the existence of an unknown colony in the region. No birds captured exhibited primary moult, which is known to occur in storm-petrels during their non-breeding season. Our data support the conclusion that the New Zealand storm-petrel breeds during January–June in northern New Zealand and that field surveys for the species on offshore islands in this region during this period are warrante

Exposure of agriculture workers to pesticides: the effect of heat on protective glove performance and skin exposure to dichlorvos

Dichlorvos is a toxic organophosphate insecticide that is used in agriculture and other insecticide applications. Dermal uptake is a known exposure route for dichlorvos and chemical protective gloves are commonly utilized. Chemical handling and application may occur in a variety of thermal environments, and the rates of both chemical permeation through gloves and transdermal penetration may vary significantly with temperature. There has been no published research on the temperature-dependent kinetics of these processes for dichlorvos and thus, this study reports on the effects of hot conditions for the concentrated and application strength chemical. Dichlorvos breakthrough times for non-disposable polyvinyl chloride (PVC) gloves at 60 °C were approximately halved compared to 25 °C for the concentrate (2 vs. 4 h) and more than halved at application strength (3 vs. >8 h). From permeation experiments covering 15–60 °C, there was a 460-fold increase in cumulative permeation over 8 h for the concentrated dichlorvos and the estimated activation energy halved. Elevated temperature was also shown to be a significant factor for human skin penetration increasing the cumulative penetration of concentrate dichlorvos from 179 ± 37 to 1315 ± 362 µg/cm² (p = 0.0032) and application strength from 29.8 ± 5.7 to 115 ± 19 µg/cm² (p = 0.0131). This work illustrates the important role temperature plays in glove performance and health risk via dermal exposure. As such, it is important to consider in-use conditions of temperature when implementing chemical hygiene programs.Leigh Thredgold, Sharyn Gaskin , Chloe Quy and Dino Pisaniell

What Do Safety Data Sheets for Artificial Stone Products Tell Us About Composition? A Comparative Analysis with Physicochemical Data

Artifcial stone (AS) is a composite material that has seen widespread use in construction, particularly for kitchen benchtops. However, fabrication processes with AS have been associated with serious lung disease. Safety data sheets (SDSs) aim to provide important information pertaining to composition and health risks. In the case of a complex mixture, SDSs may be problematic in terms of specifc information on overall health risks. To assess this issue, we compared empirically determined mineral, metallic, and organic resin content of 25 individual AS products across six suppliers, with the corresponding SDS information. X-ray diffraction was used to quantitate the mineralogical components of AS samples, and X-ray fuorescence was used to estimate the metallic components. Organic material (resin content) was estimated using weight loss during calcination. Although the resin content for all AS samples was within the SDS-reported ranges, there was considerable variability in the crystalline silica content when comparing with supplier’s SDS. Potentially toxicologically relevant metallic and mineral constituents were not reported. Some supplier SDSs were found to provide more information than others. Only one of the six suppliers provided crystalline mineral content other than silica, and only two suppliers provided any information about metals. There remains a limited understanding of lung pathogenesis from AS, and this study highlights the need for more comprehensive and standardized SDS information for risk assessment and management.Chellan Kumarasamy, Dino Pisaniello, Sharyn Gaskin, and Tony Hal

It takes two to tango: two TatA paralogues and two redox enzyme-specific chaperones are involved in the localization of twin-arginine translocase substrates in Campylobacter jejuni.

The food-borne zoonotic pathogen Campylobacter jejuni has complex electron transport chains required for growth in the host, many of which contain cofactored periplasmic enzymes localized by the twin-arginine translocase (TAT). We report here the identification of two paralogues of the TatA translocase component in C. jejuni strain NCTC 11168, encoded by cj1176c (tatA1) and cj0786 (tatA2). Deletion mutants constructed in either or both of the tatA1 and tatA2 genes displayed distinct growth and enzyme activity phenotypes. For sulphite oxidase (SorAB), the multi-copper oxidase (CueO) and alkaline phosphatase (PhoX), complete dependency on TatA1 for correct periplasmic activity was observed. However, the activities of nitrate reductase (NapA), formate dehydrogenase (FdhA) and trimethylamine N-oxide reductase (TorA) were significantly reduced in the tatA2 mutant. In contrast, the specific rate of fumarate reduction catalysed by the flavoprotein subunit of the methyl menaquinone fumarate reductase (MfrA) was similar in periplasmic fractions of both the tatA1 and the tatA2 mutants and only the deletion of both genes abolished activity. Nevertheless, unprocessed MfrA accumulated in the periplasm of the tatA1 (but not tatA2) mutant, indicating aberrant signal peptide cleavage. Surprisingly, TatA2 lacks two conserved residues (Gln8 and Phe39) known to be essential in Escherichia coli TatA and we suggest it is unable to function correctly in the absence of TatA1. Finally, only two TAT chaperones (FdhM and NapD) are encoded in strain NCTC 11168, which mutant studies confirmed are highly specific for formate dehydrogenase and nitrate reductase assembly, respectively. Thus, other TAT substrates must use general chaperones in their biogenesis

Flight Programs and X-ray Optics Development at MSFC

The X-ray astronomy group at the Marshall Space Flight Center is developing electroformed nickel/cobalt x-ray optics for suborbital and orbital experiments. Suborbital instruments include the Focusing X-ray Solar Imager (FOXSI) and Micro-X sounding rocket experiments and the HERO balloon payload. Our current orbital program is the fabrication of a series of mirror modules for the Astronomical Roentgen Telescope (ART) to be launched on board the Russian-German Spectrum Roentgen Gamma Mission (SRG.) The details and status of these various programs are presented. A second component of our work is the development of fabrication techniques and optical metrology to improve the angular resolution of thin shell optics to the arcsecond-level. The status of these x-ray optics technology developments is also presented

Influence of phosphate dosing on biofilms development on lead in chlorinated drinking water bioreactors

Phosphate dosing is used by water utilities to prevent plumbosolvency in water supply networks. However, there is a lack of knowledge regarding biofilm formation on lead and plastic materials when phosphate concentrations are modified in drinking water systems. In this study, biofilms were grown over lead coupons and PVC tubes in bioreactors supplied with local drinking water treated to provide different phosphate doses (below 1, 1 and 2 mg/L) over a period of 28 days. A range of commercial iron pellets (GEH104 and WARP) were tested aiming to maintain phosphate levels below the average 1 mg/L found in drinking water. Changes in biofilm community structure in response to three different phosphate treatments were characterised by Illumina sequencing of the 16S rRNA gene for bacteria and the ITS2 gene for fungi. Scanning electron microscopy was used to visualise physical differences in biofilm development in two types of materials, lead and PVC. The experimental results from the kinetics of phosphate absorption showed that the GEH104 pellets were the best option to, in the long term, reduce phosphate levels while preventing undesirable turbidity increases in drinking water. Phosphate-enrichment promoted a reduction of bacterial diversity but increased that of fungi in biofilms. Overall, higher phosphate levels selected for microorganisms with enhanced capabilities related to phosphorus metabolism and heavy metal resistance. This research brings new insights regarding the influence of different phosphate concentrations on mixed-species biofilms formation and drinking water quality, which are relevant to inform best management practices in drinking water treatment