[en] Wastewater is passed sequentially through an anaerobic treating zone and an oxic treating zone, followed by separation from the treated liquor of a dense sludge containing activated biomass, at least part of which is recycled to provide the activated biomass employed in treating the influent wastewater. Of the part of the sludge so recycled a minor portion is introduced into the anaerobic treating zone for admixture with the wastewater influent and the remaining major portion is introduced into the oxic treating zone, into which oxic zone oxygen-containing gas is admitted to effect oxygenation of the contents of that zone

[en] The thermal-hydrologic (TH) and coupled process models describe the evolution of a potential geologic repository as heat is released from emplaced waste. The evolution (thermal, hydrologic, chemical, and mechanical) of the engineered barrier and geologic systems is heavily dependent on the heat released by the waste packages and how the heat is transferred from the emplaced wastes through the drifts and through the repository host rock. The essential elements of this process are extracted (or abstracted) from the process-level models that incorporate the basic energy and mass conservation principles and applied to the total system models used to describe the overall performance of the potential repository. The process of total system performance assessment (TSPA) abstraction is the following. First is a description of the parameter inputs used in the process-level models. A brief description is given hereof past inputs for the viability assessment (e.g., for TSPA-VA) and current inputs for the site recommendation (TSPA-SR). This is followed by a highlight of the process-level models from which the abstractions are made. These include descriptions of TH, thermal-hydrologic-chemical (THC), and thermal-mechanical (TM) processes used to describe the performance of individual waste packages and waste emplacement drifts as well as the repository as a whole. Next is a description of what (and how) information is abstracted from the process-level models. This also includes an accounting of the features, events, and processes (FEPs) that are important to both the regulators and the international repository community in general. Finally, an identification of the TSPA model components that utilize the abstracted information to characterize the overall performance of a potential geologic repository is given

[en] X-ray computerised tomography (CT) was performed on the lungs of CBA and C57Bl mice at varying time intervals after 13 and 16 Gy irradiation to the whole thorax. With careful consideration of artefacts associated with lung cross-sectional area and breathing rate, the mean density of the lung was evaluated in Hounsfield units (CT number). In CBA mice, this parameter showed a biphasic increase in lung density with time from irradiation, corresponding to an early phase of radiation pneumonitis and a late phase dominated by pleural effusions. Reduced lung volumes were also seen during the late response and lung compression due to accumulations of pleural fluid is considered a major factor in these observations. C57Bl mice did not develop radiation pneumonitis but appeared to be equally responsive to later radiation-induced increases in lung density. The results obtained from CT-derived densitometry compared well with measurements gained from functional and survival endpoints. X-ray CT provides a sensitive and informative technique for assessing the extent of radiation injury to the mouse lung and is potentially useful for quantifying the counterpart in patients. (orig.)

[en] ⁹⁹Tc is one of the most important isotopes likely to be disposed of in the proposed UK Geological Disposal Facility for higher-activity radioactive wastes, due to its long half-life, high fission yield and ability to migrate through the geosphere as the pertechnetate ion. However, much of the technetium is likely to be in the lower oxidation state of Tc(IV) due to the low Eh in the near field. Batch sorption experiments across the pH range have been performed on Tc(IV) using ^95mTc as a spike in the presence of some representative clay minerals (bentonite, smectite, kaolinite, montmorillonite and illite). Tc(IV) solutions were used at trace concentrations to avoid precipitation as technetium dioxide. Values for the partition coefficient (R_d) were found to range from 7 to 2e5 ml/g. R_d was heavily dependent on pH in all cases, with the highest values being found in the circumneutral area. These data will inform the performance assessment for the behaviour of technetium in the near-field of the UK's planned higher-activity wastes GDF. Surface complexation modelling of the data has been performed.

[en] The charge state distribution following the positron decay of 21Na has been measured, with a larger than expected fraction of the daughter 21Ne in positive charge states. No dependence on either the positron or recoil nucleus energy is observed. The data is compared to a simple model based on the sudden approximation. Calculations suggest a small but important contribution from recoil ionization has important consequences for precision beta decay correlation experiments detecting recoil ions

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[en] This study has indicated that CT scanning is an extremely useful technique for non-invasively monitoring the increase in lung density caused by irradiation. However, careful consideration needs to be given to artifacts and variations associated with lung cross-sectional area and breathing rate (Nicholas and Down, 1985). CT scanning of mice subjected to whole thorax irradiation yields lung density measurements which compare well with breathing rate measurements and also indicate the type of injury sustained. Furthermore, compensatory hypertrophy of shielded lung tissue following hemithorax irradiation can also be visualised and quantified with CT. These results emphasise the potential value of X-ray CT for quantifying lung density changes in patients receiving radiotherapy to the thorax. Clinical studies are already being conducted at the Royal Marsden Hospital. (UK)

[en] Recent work has indicated that ghost imaging may have applications in standoff sensing. However, most theoretical work has addressed transmission-based ghost imaging. To be a viable remote-sensing system, the ghost imager needs to image rough-surfaced targets in reflection through long, turbulent optical paths. We develop, within a Gaussian-state framework, expressions for the spatial resolution, image contrast, and signal-to-noise ratio of such a system. We consider rough-surfaced targets that create fully developed speckle in their returns and Kolmogorov-spectrum turbulence that is uniformly distributed along all propagation paths. We address both classical and nonclassical optical sources, as well as a computational ghost imager.

[en] Quantum mechanical simulation of realistic models of nanostructured systems, such as nanocrystals and crystalline interfaces, demands computational methods combining high-accuracy with low-order scaling with system size. Blöchl’s projector augmented wave (PAW) approach enables all-electron (AE) calculations with the efficiency and systematic accuracy of plane-wave pseudopotential calculations. Meanwhile, linear-scaling (LS) approaches to density functional theory (DFT) allow for simulation of thousands of atoms in feasible computational effort. This article describes an adaptation of PAW for use in the LS-DFT framework provided by the ONETEP LS-DFT package. ONETEP uses optimisation of the density matrix through in situ -optimised local orbitals rather than the direct calculation of eigenstates as in traditional PAW approaches. The method is shown to be comparably accurate to both PAW and AE approaches and to exhibit improved convergence properties compared to norm-conserving pseudopotential methods. (paper)