The Separation of 241

Electrical power sources used in outer planet missions are a key enabling technology for data acquisition and communications. State–of-the-art power sources generate electricity from alpha decay of 238Pu via thermoelectric conversion. However, production of 238Pu requires specialist facilities including a nuclear reactor, a source of 237Np for target irradiation and hotcells to chemically separate neptunium and plutonium within the irradiated targets. These specialist facilities are expensive to build and operate, so naturally, a more economical alternative is attractive to the industry. Within Europe 241Am is considered a promising alternative heat source for radioisotope thermoelectric generators (RTGs) and radioisotope heating units (RHUs). As a daughter product of 241Pu decay, 241Am exists in 1000 kgs quantities within the UK civil plutonium stockpile. A chemical separation process is required to extract the 241Am in a pure form and this paper describes the AMPPEX process (Americium and Plutonium Purification by Extraction), successfully developed over the past five years to isolate 241Am in high yield (> 99%) and to a high purity (> 99%). The process starts by dissolving plutonium dioxide in nitric acid with the aid of a silver(II) catalyst, which is generated electrochemically. The solution is then conditioned and fed to a PUREX type solvent extraction process, where the plutonium is separated from the americium and silver. The plutonium is converted back to plutonium dioxide and the americium is fed forward to a second solvent extraction step. Here the americium is selectively extracted leaving the silver in the aqueous phase. The americium is stripped from the solvent and recovered from solution as americium oxalate, which is calcined to give americium dioxide as the final product. This paper will describe the development of the separation process over a series of six solvent extraction separation trials using centrifugal contactors. The material produced (~ 4g 241Am) was used to make ceramic pellets to establish the behaviour of americium oxide material under high temperature (1450°C) sintering conditions. The chemical separation process is now demonstrated at concentrations expected on the full scale facility taking this process to TRL 4-5

Insights into the high-energy γ-ray emission of Markarian 501 from extensive multifrequency observations in the Fermi era

We report on the γ-ray activity of the blazar Mrk 501 during the first 480 days of Fermi operation. We find that the average Large Area Telescope (LAT) γ-ray spectrum of Mrk 501 can be well described by a single power-law function with a photon index of 1.78 ± 0.03. While we observe relatively mild flux variations with the Fermi-LAT (within less than a factor of two), we detect remarkable spectral variability where the hardest observed spectral index within the LAT energy range is 1.52 ± 0.14, and the softest one is 2.51 ± 0.20. These unexpected spectral changes do not correlate with the measured flux variations above 0.3 GeV. In this paper, we also present the first results from the 4.5 month long multifrequency campaign (2009 March 15-August 1) on Mrk 501, which included the Very Long Baseline Array (VLBA), Swift, RXTE, MAGIC, and VERITAS, the F-GAMMA, GASP-WEBT, and other collaborations and instruments which provided excellent temporal and energy coverage of the source throughout the entire campaign. The extensive radio to TeV data set from this campaign provides us with the most detailed spectral energy distribution yet collected for this source during its relatively low activity. The average spectral energy distribution of Mrk 501 is well described by the standard one-zone synchrotron self-Compton (SSC) model. In the framework of this model, we find that the dominant emission region is characterized by a size ≲0.1 pc (comparable within a factor of few to the size of the partially resolved VLBA core at 15-43 GHz), and that the total jet power (≃1044 erg s-1) constitutes only a small fraction (∼10-3) of the Eddington luminosity. The energy distribution of the freshly accelerated radiating electrons required to fit the time-averaged data has a broken power-law form in the energy range 0.3 GeV-10 TeV, with spectral indices 2.2 and 2.7 below and above the break energy of 20 GeV. We argue that such a form is consistent with a scenario in which the bulk of the energy dissipation within the dominant emission zone of Mrk 501 is due to relativistic, proton-mediated shocks. We find that the ultrarelativistic electrons and mildly relativistic protons within the blazar zone, if comparable in number, are in approximate energy equipartition, with their energy dominating the jet magnetic field energy by about two orders of magnitude. © 2011. The American Astronomical Society

Conidiobolomicose causada por Conidiobolus lamprauges em ovinos no Estado de Santa Catarina Conidiobolomycosis caused by Conidiobolus lamprauges in sheep in the state of Santa Catarina, Brazil

Descreve-se um surto de conidiobolomicose em ovinos no Estado de Santa Catarina. O surto ocorreu entre os meses de dezembro e março de 2006, no município de Santo Amaro da Imperatriz, região litorânea do Estado. A propriedade possuía 75 ovinos da raça Santa Inês e seis desses animais adoeceram. Clinicamente os animais doentes apresentavam dificuldade respiratória, corrimento nasal seroso a mucossanguinolento e, por vezes exolftalmia. Na necropsia verificou-se uma massa amarelada na região etmoidal e adjacências que, às vezes, atingia os linfonodos regionais, cérebro, globo ocular e pleura. Microscopicamente a massa caracterizava-se por infiltrado inflamatório granulomatoso com áreas necróticas associadas a hifas largas pouco ramificadas. Através de exame molecular detectou-se DNA de Conidiobolus lamprauges. Os aspectos clínicos, epidemiológicos, macroscópicos, microscópicos e moleculares caracterizam a conidiobolomicose causada por Conidiobolus lamprauges em ovinos.<br>An outbreak of conidiobolomycosis affecting sheep in the State of Santa Catarina, Southern Brazil is reported. The disease occurred in six Santa Inês breed sheep from a flock of 75 during the rainy season. Common clinical signs were noisy respiration and dyspnea, serous to mucosanguineous nasal discharge and exophthalmus. At necropsy there was a dense yellow mass in the nasopharyngeal area affecting the ethmoidal region, turbinate bones and occasionally limph nodes, central nervous system and pleura. Histopathologycally there was multifocal granulomas whith an eosinophilic necrotic reaction containing ribbon type hyphae similar to zygomycetous fungi. At molecular examination Conidiobolus lamprauges DNA was detected. The clinical, epidemiological, macroscopical, microscopical and molecular aspects characterize conidiobolomycosis caused by Conidiobolus lamprauges in sheep

Epstein-Barr virus replication within pulmonary epithelial cells in cryptogenic fibrosing alveolitis

BACKGROUND--Cryptogenic fibrosing alveolitis (synonymous with idiopathic pulmonary fibrosis) is a clinically heterogeneous condition in which the precipitating factor is unclear. Both environmental and infective factors have been implicated. An association between Epstein-Barr virus (EBV) and cryptogenic fibrosing alveolitis was suggested over a decade ago by a study based on EBV serology, but the significance of this has been unclear. METHODS--Lung tissue obtained surgically from patients (n = 20) with cryptogenic fibrosing alveolitis was investigated for evidence of EBV replication and compared with lung tissue from 21 control patients. Fourteen of the 20 patients had received no specific therapy for cryptogenic fibrosing alveolitis at the time of biopsy. Monoclonal antibodies directed against the EBV viral antigens, EBV viral capsid antigen (VCA) and gp 340/220 antigen, which are expressed during the lytic phase of the EBV life cycle, were studied. RESULTS--Fourteen (70%) of the 20 patients with cryptogenic fibrosing alveolitis were positive for both EBV VCA and gp 340/220 compared with two (9%) of the 21 controls. In the patients with cryptogenic fibrosing alveolitis viral replication was localised to pulmonary epithelial cells using epithelial cell markers, and immunohistochemical analysis confirmed the staining to be within type II alveolar cells. CONCLUSIONS--This is the first report of in vivo EBV replication within epithelial cells of the lower respiratory tract in an immunocompetent human host. Furthermore, this suggests that EBV may be an immune trigger or contribute to lung injury in cryptogenic fibrosing alveolitis, thus offering a potential new avenue of treatment