55 research outputs found
An Electron Paramagnetic Resonance (EPR) spectroscopy study on the γ-irradiation sterilization of the pharmaceutical excipient l-histidine: Regeneration of the radicals in solution
The effects of γ-radiation sterilization on the parenteral excipient L-histidine were analysed by means of EPR spectroscopy. The irradiation process was found to induce the formation of a deamination radical which was persistent in the solid state. The nature and reactivity of the radicals following dissolution in water was evaluated using spin-trapping EPR experiments. The deamination radical was found to regenerate in solution in the presence of trace metals, potentially leading to radical induced degradation reactions occurring up to an hour after the dissolution process. Understanding this process is significant for the improved design of parental pharmaceutical formulations in which unwanted radical reactions after γ radiation sterilization could lead to degradation of active ingredients
Very high energy observations of the BL Lac objects 3C 66A and OJ 287
Using the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE), we
have observed the BL Lac objects 3C 66A and OJ 287. These are members of the
class of low-frequency-peaked BL Lac objects (LBLs) and are two of the three
LBLs predicted by Costamante and Ghisellini to be potential sources of very
high energy (>100 GeV) gamma-ray emission. The third candidate, BL Lacertae,
has recently been detected by the MAGIC collaboration. Our observations have
not produced detections; we calculate a 99% CL upper limit of flux from 3C 66A
of 0.15 Crab flux units and from OJ 287 our limit is 0.52 Crab. These limits
assume a Crab-like energy spectrum with an effective energy threshold of 185
GeV.Comment: 24 pages, 15 figures, Accepted for publication in Astroparticle
Physic
Perspectives in visual imaging for marine biology and ecology: from acquisition to understanding
Durden J, Schoening T, Althaus F, et al. Perspectives in Visual Imaging for Marine Biology and Ecology: From Acquisition to Understanding. In: Hughes RN, Hughes DJ, Smith IP, Dale AC, eds. Oceanography and Marine Biology: An Annual Review. 54. Boca Raton: CRC Press; 2016: 1-72
A ROSAT HRI study of the interaction of the X-ray-emitting gas and radio lobes of NGC 1275
A re-examination of early sodium-water reaction experiments in the context of Design Basis Accidents
SIGLEAvailable from British Library Document Supply Centre- DSC:9091.9F(ND-R--1265(D)) / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Complications in the tissue integrated prostheses components: clinical and mechanical evaluation
Storm in a "Teacup": A Radio-quiet Quasar with ≈10 kpc Radio-emitting Bubbles and Extreme Gas Kinematics
We present multi-frequency (1-8 GHz) Very Large Array data, combined with VIsible MultiObject Spectrograph integral field unit data and Hubble Space Telescope imaging, of a z = 0.085 radio-quiet type 2 quasar (with L 1.4 GHz ≈ 5 × 1023 W Hz–1 and L AGN ≈ 2 × 1045 erg s–1). Due to the morphology of its emission-line region, the target (J1430+1339) has been referred to as the "Teacup" active galactic nucleus (AGN) in the literature. We identify "bubbles" of radio emission that are extended ≈10-12 kpc to both the east and west of the nucleus. The edge of the brighter eastern bubble is co-spatial with an arc of luminous ionized gas. We also show that the "Teacup" AGN hosts a compact radio structure, located ≈0.8 kpc from the core position, at the base of the eastern bubble. This radio structure is co-spatial with an ionized outflow with an observed velocity of v = –740 km s–1. This is likely to correspond to a jet, or possibly a quasar wind, interacting with the interstellar medium at this position. The large-scale radio bubbles appear to be inflated by the central AGN, which indicates that the AGN can also interact with the gas on gsim 10 kpc scales. Our study highlights that even when a quasar is formally "radio-quiet" the radio emission can be extremely effective for observing the effects of AGN feedback
The REFLEX Cluster Survey: observing strategy and first results on large-scale structure.
We give a general description of the optical observing strategy of the
ROSAT-ESO Flux-Limited X-ray (REFLEX) cluster survey. This presently includes
460 clusters of galaxies selected from the ROSAT All-Sky Survey in the Southern
hemisphere, to a flux limit of 3 10^{-12} erg s^{-1} cm^{-2}. Redshifts are now
measured for 95% of this sample. Work is in progress to complete this coverage,
and then extend the sample to fainter fluxes. A few highlights on the
large-scale distribution of REFLEX clusters and their clustering properties are
also discussed.Comment: Latex; 12 pages with colour PS figures. To appear in "The ESO
Messenger", 95, p.2
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