475 research outputs found

    Reactivity worth of control rods in the beryllium oxide moderated pebble bed reactor.

    Get PDF
    Preliminary and final studies are reported for the worth of tubular control rods in a beryllium oxide moderated pebble bed reactor system. In the preliminary study the consideration of ball flow forces the investigation of a number of control rod arrangements. In addition, a range of rod sizes is considered. In the final study a particular rod size and pattern is chosen for more detailed investigation. For the intermediate reactor cores under consideration the control rods must absorb appreciably in the KeV region. A feature of the final study is the accurate way the epithermal absorption can be taken into account while using a three group model in the reflected reactor. The preliminary study is not so accurate but is useful for comparative purposes

    Industrial work placement in higher education: a study of civil engineering student engagement

    Get PDF
    For civil engineering undergraduates, the opportunity to spend a period of time in formal industrial work placement provides an invaluable learning experience. This paper reviews student engagement with short-term industrial placement and provides analysis of questionnaires (n=174) returned by undergraduates studying civil engineering at four Higher Education Institutes (HEI’s) in the West of Scotland. The data captures industrial placement statistics, employability skill-sets and presents brief testimonies from students. Whilst the journey to becoming a professional civil engineer is undoubtedly enhanced by short-term placement clear opportunities exist for HEI’s to affect and change existing pedagogical discourse. Commentary is likely to resonate beyond civil engineering and serve as a timely reminder of the need to re-invigorate academia / industry curriculum partnerships

    Proton acceleration by irradiation of isolated spheres with an intense laser pulse

    Get PDF
    We report on experiments irradiating isolated plastic spheres with a peak laser intensity of 2-3 x 10(20) W cm(-2). With a laser focal spot size of 10 mu m full width half maximum (FWHM) the sphere diameter was varied between 520 nm and 19.3 mu m. Maximum proton energies of similar to 25 MeV are achieved for targets matching the focal spot size of 10 mu m in diameter or being slightly smaller. For smaller spheres the kinetic energy distributions of protons become nonmonotonic, indicating a change in the accelerating mechanism from ambipolar expansion towards a regime dominated by effects caused by Coulomb repulsion of ions. The energy conversion efficiency from laser energy to proton kinetic energy is optimized when the target diameter matches the laser focal spot size with efficiencies reaching the percent level. The change of proton acceleration efficiency with target size can be attributed to the reduced cross-sectional overlap of subfocus targets with the laser. Reported experimental observations are in line with 3D3V particle in cell simulations. They make use of well-defined targets and point out pathways for future applications and experiments.DFG via the Cluster of Excellence Munich-Centre for Advanced Photonics (MAP) Transregio SFB TR18NNSA DE-NA0002008Super-MUC pr48meIvo CermakCGC Instruments in design and realization of the Paul trap systemIMPRS-APSLMUexcellent Junior Research FundDAAD|ToIFEEuropean Union's Horizon research and innovation programme 633053Physic

    Structure-based design and synthesis of antiparasitic pyrrolopyrimidines targeting pteridine reductase 1

    Get PDF
    The treatment of Human African Trypanosomiasis remains a major unmet health need in sub-Saharan Africa. Approaches involving new molecular targets are important and pteridine reductase 1 (PTR1), an enzyme that reduces dihydrobiopterin in Trypanosoma spp. has been identified as a candidate target and it has been shown previously that substituted pyrrolo[2,3-d]pyrimidines are inhibitors of PTR1 from T. brucei (J. Med. Chem. 2010, 53, 221-229). In this study, 61 new pyrrolo[2,3-d]pyrimidines have been prepared, designed with input from new crystal structures of 23 of these compounds complexed with PTR1, and evaluated in screens for enzyme inhibitory activity against PTR1 and in vitro antitrypanosomal activity. 8 compounds were sufficiently active in both screens to take forward to in vivo evaluation. Thus although evidence for trypanocidal activity in a stage I disease model in mice was obtained, the compounds were too toxic to mice for further development

    Emerging nuclear collectivity in 124−130^{124-130}Te

    Full text link
    The emergence of nuclear collectivity near doubly-magic 132^{132}Sn was explored along the stable, even-even 124−130^{124-130}Te isotopes. Preliminary measurements of the B(E2;41+→21+)B(E2;4^{+}_{1}\rightarrow2^{+}_{1}) transition strengths are reported from Coulomb excitation experiments primarily aimed at measuring the gg factors of the 41+4^{+}_{1} states. Isotopically enriched Te targets were excited by 198-205 MeV 58^{58}Ni beams. A comparison of transition strengths obtained is made to large-scale shell-model calculations with successes and limitations discussed.Comment: 5 pages, 3 figures, Submitted to Proceedings HIAS 2019, EPJ Web of Conference
    • …
    corecore