305 research outputs found
Cost of producing school meals in Wales : a report commissioned from the Wales Audit Office by the Welsh Assembly Government
The financial modelling to identify local authority expenditure on school meals is not yet sufficiently refined or owned by the authorities to serve as a robust and comprehensive management tool. Wales spent more than ÂŁ90 million on the school meal service (42 per cent of which was spent by local authorities) during 2007-08 and the cost, funding and takeup of schools meals varied considerably across local authorities
Water purification by ion exchange mixed beds
Ion exchange is used extensively for the removal of ionised impurities
found in natural waters. The final stage in the production of ultra
pure water is normally a bed of mixed anion and cation exchange resins.
Three areas within the operating cycle of a regenerable mixed bed -
resin separation, resin mixing and anion exchange kinetics - have
been investigated.
Complete separation of the two resins by backwashing, prior to chemical
regeneration, is necessary to prevent the subsequent release of trace
impurities into the purified water. Various published models of
particle segregation by backwashing were examined but none accurately
described the separation of two ion exchange resins with similar bead
size distributions and densities. A new model has been proposed based
on variations in fluidised bed porosity combined with overlapping
bulk circulation cells of particles. A graphical technique has been
developed to predict resin separability and the predictions compared
with practical data. The effects of variations in bead size, bead
density, backwash flow rate and temperature have been calculated. The
variations in bead density with ionic form and polymer/matrix type
of the exchanger have been measured.
Following regeneration the resins are remixed by air agitation of a
resin/water slurry. A mechanism to describe the progressive stages of
air mixing has been proposed, based on bubble transport and bulk
circulation of resin beads. The subsequent sedimentation of the resins
was also considered. Laboratory and full scale studies confirmed the
predicted effects of mixing fault conditions, particularly re-separation
of the mixed resins.
A mass transfer equation has been developed to describe the leakage
of influent ions through a column of exchange resins. In conjunction
with laboratory column tests the equation has been used to investigate
the influence on anion exchange of polymer/matrix type, influent anion
and the presence of foulants on the resin beads. Sulphate and phosphate
ions exchange more slowly than monovalent chloride and nitrate ions.
On a fouled exchanger the rate of sulphate exchange deteriorates more
rapidly and seriously than for chloride exchange. This has been
attributed to steric hindrance of the divalent sulphate ion.
A laboratory method has been developed for the routine assessment of
mixed bed anion exchangers and the prediction of their performance
potential in service, with particular application to condensate
purification for boiler feedwater
A review of the analytical techniques for the detection of anabolic–androgenic steroids within biological matrices
Anabolic–androgenic steroids (AASs) and other image and performance enhancing drugs (IPEDs) are controlled by governments and sport institutions such as the World Anti-doping Agency (WADA). Although elite athletes and professional bodybuilders are the most visible AAS abusers, the introduction of the internet has increased the accessibility of AASs, with use being observed among recreational gym goers at increasing prevalence. Despite reported increase in use, routine analysis for these substances is uncommon, with many forensic laboratories opting to outsource AAS analysis. This review collates information regarding the extraction and analysis of AASs from various biological matrices with the considered purpose of providing a reference for the development of AAS methods to allow for routine detection by forensic laboratories
Third Dredge-up in Low Mass Stars: Solving the LMC Carbon Star Mystery
A long standing problem with asymptotic giant branch (AGB) star models has
been their inability to produce the low-luminosity carbon stars in the Large
and Small Magellanic Clouds. Dredge-up must begin earlier and extend deeper. We
find this for the first time in our models of LMC metallicity. Such features
are not found in our models of SMC metallicity. The fully implicit and
simultaneous stellar evolution code STARS has been used to calculate the
evolution of AGB stars with metallicities of Z=0.008 and Z=0.004, corresponding
to the observed metallicities of the Large and Small Magellanic Clouds,
respecitively. Third dredge-up occurs in stars of 1Msol and above and carbon
stars were found for models between 1Msol and 3Msol. We use the detailed models
as input physics for a population synthesis code and generate carbon star
luminosity functions. We now find that we are able to reproduce the carbon star
luminosity function of the LMC without any manipulation of our models. The SMC
carbon star luminosity function still cannot be produced from our detailed
models unless the minimum core mass for third dredge-up is reduced by 0.06Msol.Comment: 6 pages, 5 figures. Accepted for publication in MNRA
Evaluating different methods of MR-based motion correction in simultaneous PET/MR using a head phantom moved by a robotic system
BACKGROUND: Due to comparatively long measurement times in simultaneous positron emission tomography and magnetic resonance (PET/MR) imaging, patient movement during the measurement can be challenging. This leads to artifacts which have a negative impact on the visual assessment and quantitative validity of the image data and, in the worst case, can lead to misinterpretations. Simultaneous PET/MR systems allow the MR-based registration of movements and enable correction of the PET data. To assess the effectiveness of motion correction methods, it is necessary to carry out measurements on phantoms that are moved in a reproducible way. This study explores the possibility of using such a phantom-based setup to evaluate motion correction strategies in PET/MR of the human head. METHOD: An MR-compatible robotic system was used to generate rigid movements of a head-like phantom. Different tools, either from the manufacturer or open-source software, were used to estimate and correct for motion based on the PET data itself (SIRF with SPM and NiftyReg) and MR data acquired simultaneously (e.g. MCLFIRT, BrainCompass). Different motion estimates were compared using data acquired during robot-induced motion. The effectiveness of motion correction of PET data was evaluated by determining the segmented volume of an activity-filled flask inside the phantom. In addition, the segmented volume was used to determine the centre-of-mass and the change in maximum activity concentration. RESULTS: The results showed a volume increase between 2.7 and 36.3% could be induced by the experimental setup depending on the motion pattern. Both, BrainCompass and MCFLIRT, produced corrected PET images, by reducing the volume increase to 0.7–4.7% (BrainCompass) and to -2.8–0.4% (MCFLIRT). The same was observed for example for the centre-of-mass, where the results show that MCFLIRT (0.2–0.6 mm after motion correction) had a smaller deviation from the reference position than BrainCompass (0.5–1.8 mm) for all displacements. CONCLUSIONS: The experimental setup is suitable for the reproducible generation of movement patterns. Using open-source software for motion correction is a viable alternative to the vendor-provided motion-correction software. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40658-022-00442-6
Market potential of nanoremediation in Europe – Market drivers and interventions identified in a deliberative scenario approach
A deliberate expert-based scenario approach is applied to better understand the likely determinants of the evolution of the market for nanoparticles use in remediation in Europe until 2025. An initial set of factors had been obtained from a literature review and was complemented by a workshop and key-informant interviews. In further expert engaging formats – focus groups, workshops, conferences, surveys – this initial set of factors was condensed and engaged experts scored the factors regarding their importance for being likely to influence the market development. An interaction matrix was obtained identifying the factors being most active in shaping the market development in Europe by 2025, namely “Science-Policy-Interface” and “Validated information on nanoparticle application potential”. Based on these, potential future states were determined and development of factors discussed. Conclusions are offered on achievable interventions to enhance nanoremediation deployment
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