16 research outputs found
X-RED: A Satellite Mission Concept To Detect Early Universe Gamma Ray Bursts
Gamma ray bursts (GRBs) are the most energetic eruptions known in the
Universe. Instruments such as Compton-GRO/BATSE and the GRB monitor on BeppoSAX
have detected more than 2700 GRBs and, although observational confirmation is
still required, it is now generally accepted that many of these bursts are
associated with the collapse of rapidly spinning massive stars to form black
holes. Consequently, since first generation stars are expected to be very
massive, GRBs are likely to have occurred in significant numbers at early
epochs. X-red is a space mission concept designed to detect these extremely
high redshifted GRBs, in order to probe the nature of the first generation of
stars and hence the time of reionisation of the early Universe. We demonstrate
that the gamma and x-ray luminosities of typical GRBs render them detectable up
to extremely high redshifts (z~10-30), but that current missions such as HETE2
and SWIFT operate outside the observational range for detection of high
redshift GRB afterglows. Therefore, to redress this, we present a complete
mission design from the science case to the mission architecture and payload,
the latter comprising three instruments, namely wide field x-ray cameras to
detect high redshift gamma-rays, an x-ray focussing telescope to determine
accurate coordinates and extract spectra, and an infrared spectrograph to
observe the high redshift optical afterglow. The mission is expected to detect
and identify for the first time GRBs with z > 10, thereby providing constraints
on properties of the first generation of stars and the history of the early
Universe.Comment: 14 pages, 10 figures, spie.cls neede
Copper oxide nanoparticle toxicity profiling using untargeted metabolomics
BackgroundThe rapidly increasing number of engineered nanoparticles (NPs), and products containing NPs, raises concerns for human exposure and safety. With this increasing, and ever changing, catalogue of NPs it is becoming more difficult to adequately assess the toxic potential of new materials in a timely fashion. It is therefore important to develop methods which can provide high-throughput screening of biological responses. The use of omics technologies, including metabolomics, can play a vital role in this process by providing relatively fast, comprehensive, and cost-effective assessment of cellular responses. These techniques thus provide the opportunity to identify specific toxicity pathways and to generate hypotheses on how to reduce or abolish toxicity.ResultsWe have used untargeted metabolome analysis to determine differentially expressed metabolites in human lung epithelial cells (A549) exposed to copper oxide nanoparticles (CuO NPs). Toxicity hypotheses were then generated based on the affected pathways, and critically tested using more conventional biochemical and cellular assays. CuO NPs induced regulation of metabolites involved in oxidative stress, hypertonic stress, and apoptosis. The involvement of oxidative stress was clarified more easily than apoptosis, which involved control experiments to confirm specific metabolites that could be used as standard markers for apoptosis; based on this we tentatively propose methylnicotinamide as a generic metabolic marker for apoptosis.ConclusionsOur findings are well aligned with the current literature on CuO NP toxicity. We thus believe that untargeted metabolomics profiling is a suitable tool for NP toxicity screening and hypothesis generation