Computational prediction of the refinement of oxide agglomerates in a physical conditioning process for molten aluminium alloy

Physically conditioning molten scrap aluminium alloys using high shear processing (HSP) was recently found to be a promising technology for purification of contaminated alloys. HSP refines the solid oxide agglomerates in molten alloys, so that they can act as sites for the nucleation of Fe-rich intermetallic phases which can subsequently be removed by the downstream de-drossing process. In this paper, a computational modelling for predicting the evolution of size of oxide clusters during HSP is presented. We used CFD to predict the macroscopic flow features of the melt, and the resultant field predictions of temperature and melt shear rate were transferred to a population balance model (PBM) as its key inputs. The PBM is a macroscopic model that formulates the microscopic agglomeration and breakage of a population of a dispersed phase. Although it has been widely used to study conventional deoxidation of liquid metal, this is the first time that PBM has been used to simulate the melt conditioning process within a rotor/stator HSP device. We employed a method which discretizes the continuous profile of size of the dispersed phase into a collection of discrete bins of size, to solve the governing population balance equation for the size of agglomerates. A finite volume method was used to solve the continuity equation, the energy equation and the momentum equation. The overall computation was implemented mainly using the FLUENT module of ANSYS. The simulations showed that there is a relatively high melt shear rate between the stator and sweeping tips of the rotor blades. This high shear rate leads directly to significant fragmentation of the initially large oxide aggregates. Because the process of agglomeration is significantly slower than the breakage processes at the beginning of HSP, the mean size of oxide clusters decreases very rapidly. As the process of agglomeration gradually balances the process of breakage, the mean size of oxide clusters converges to a steady value. The model enables formulation of the quantitative relationship between the macroscopic flow features of liquid metal and the change of size of dispersed oxide clusters, during HSP. It predicted the variation in size of the dispersed phased with operational parameters (including the geometry and, particularly, the speed of the rotor), which is of direct use to experimentalists optimising the design of the HSP device and its implementation.This research is financially supported by the EC FP7 project “High Shear Processing of Recycled Aluminium Scrap for Manufacturing High Performance Aluminium Alloys” (Grant No. 603577)

Metagenomic sequencing suggests a diversity of RNA interference-like responses to viruses across multicellular eukaryotes.

Funding: This work was funded by a Leverhulme Trust grant to DJO, GNS and FMW (RPG-2013-168; https://www.leverhulme.ac.uk/), and work in DJO’s lab was partly supported by a Wellcome Trust strategic award to the Centre for Immunity, Infection and Evolution (WT095831; http://www.wellcome.ac.uk/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewe

The potential of an observational data set for calibration of a computationally expensive computer model

PublishedJournal ArticleWe measure the potential of an observational data set to constrain a set of inputs to a complex and computationally expensive computer model. We use each member in turn of an ensemble of output from a computationally expensive model, corresponding to an observable part of a modelled system, as a proxy for an observational data set. We argue that, given some assumptions, our ability to constrain uncertain parameter inputs to a model using its own output as data, provides a maximum bound for our ability to constrain the model inputs using observations of the real system. The ensemble provides a set of known parameter input and model output pairs, which we use to build a computationally effic. © 2013 Author(s).This work was supported by funding from the ice2sea programme from the European Union 7th Framework Programme, grant number 226375. Ice2sea contribution number 154

An instrument to measure fast gas phase radical kinetics at hight temperatures and pressures

Fast radical reactions are central to the chemistry of planetary atmospheres and combustion systems. Laser-induced fluorescence is a highly sensitive and selective technique that can be used to monitor a number of radical species in kinetics experiments, but is typically limited to low pressure systems owing to quenching of fluorescent states at higher pressures. The design and characterisation of an instrument is reported using laser-induced fluorescence detection to monitor fast radical kinetics (up to 25,000 s-1) at high temperatures and pressures by sampling from a high pressure reaction region to a low pressure detection region. Kinetics have been characterised at temperatures reaching 740 K and pressures up to 2 atm, with expected maximum operational conditions of up to ~ 900 K and ~ 5 atm. The distance between the point of sampling from the high pressure region and the point of probing within the low pressure region is critical to the measurement of fast kinetics. The instrumentation described in this work can be applied to the measurement of kinetics relevant to atmospheric and combustion chemistry

Impact of meltwater on high-latitude early Last Interglacial climate

Recent data compilations of the early Last Interglacial period have indicated a bipolar temperature response at 130 ka, with colder-than-present temperatures in the North Atlantic and warmer-than-present temperatures in the Southern Ocean and over Antarctica. However, climate model simulations of this period have been unable to reproduce this response, when only orbital and greenhouse gas forcings are considered in a climate model framework. Using a full-complexity general circulation model we perform climate model simulations representative of 130 ka conditions which include a magnitude of freshwater forcing derived from data at this time. We show that this meltwater from the remnant Northern Hemisphere ice sheets during the glacial-interglacial transition produces a modelled climate response similar to the observed colder-than-present temperatures in the North Atlantic at 130 ka and also results in warmer-than-present temperatures in the Southern Ocean via the bipolar seesaw mechanism. Further simulations in which the West Antarctic Ice Sheet is also removed lead to warming in East Antarctica and the Southern Ocean but do not appreciably improve the model-data comparison. This integrated model-data approach provides evidence that Northern Hemisphere freshwater forcing is an important player in the evolution of early Last Interglacial climate.This work was carried out with funding from the UK-NERC consortium iGlass (NE/I009906/1) and is also a contribution to the European Union’s Seventh Framework programme (FP7/2007–2013) under grant agreement 243908, “Past4Future. Climate change – Learning from the past climate”. This is Past4Future contribution no. 85

Effect of varying the concentrations of carbohydrate and milk protein in rehydration solutions ingested after exercise in the heat

The present study investigated the relationship between the milk protein content of a rehydration solution and fluid balance after exercise-induced dehydration. On three occasions, eight healthy males were dehydrated to an identical degree of body mass loss (BML, approximately 1.8 %) by intermittent cycling in the heat, rehydrating with 150 % of their BML over 1 h with either a 60 g/l carbohydrate solution (C), a 40 g/l carbohydrate, 20 g/l milk protein solution (CP20) or a 20 g/l carbohydrate, 40 g/l milk protein solution (CP40). Urine samples were collected pre-exercise, post-exercise, post-rehydration and for a further 4 h. Subjects produced less urine after ingesting the CP20 or CP40 drink compared with the C drink (P<0.01), and at the end of the study, more of the CP20 (59 (SD 12) %) and CP40 (64 (SD 6) %) drinks had been retained compared with the C drink (46 (SD 9) %) (P,0.01). At the end of the study, whole-body net fluid balance was more negative for trial C (2470 (SD 154) ml) compared with both trials CP20 (2181 (SD 280) ml) and CP40 (2107 (SD 126) ml) (P<0.01). At 2 and 3 h after drink ingestion, urine osmolality was greater for trials CP20 and CP40 compared with trial C (P<0.05). The present study further demonstrates that after exercise-induced dehydration, a carbohydrate–milk protein solution is better retained than a carbohydrate solution. The results also suggest that high concentrations of milk protein are not more beneficial in terms of fluid retention than low concentrations of milk protein following exercise-induced dehydration

A t(4;12)(q11;p13) in a patient with coincident CLL at the same time of AML diagnosis

Case report of a translocation : A t(4;12)(q11;p13) in a patient with coincident CLL at the same time of AML diagnosis

Does training with amplitude modulated tones affect tone-vocoded speech perception?

Temporal-envelope cues are essential for successful speech perception. We asked here whether training on stimuli containing temporal-envelope cues without speech content can improve the perception of spectrally-degraded (vocoded) speech in which the temporal-envelope (but not the temporal fine structure) is mainly preserved. Two groups of listeners were trained on different amplitude-modulation (AM) based tasks, either AM detection or AM-rate discrimination (21 blocks of 60 trials during two days, 1260 trials; frequency range: 4Hz, 8Hz, and 16Hz), while an additional control group did not undertake any training. Consonant identification in vocoded vowel-consonant-vowel stimuli was tested before and after training on the AM tasks (or at an equivalent time interval for the control group). Following training, only the trained groups showed a significant improvement in the perception of vocoded speech, but the improvement did not significantly differ from that observed for controls. Thus, we do not find convincing evidence that this amount of training with temporal-envelope cues without speech content provide significant benefit for vocoded speech intelligibility. Alternative training regimens using vocoded speech along the linguistic hierarchy should be explored

Recurrent brain ischaemia and deep vein thrombosis: the clot thickens

A 65-year-old man presented with two transient ischaemic attacks, and was then found to have a deep vein thrombosis. He later had recurrent ischaemic strokes. After thorough investigation, the only cause we identified was a previously undiagnosed metastatic pancreatic cancer. We describe the assessment of this presentation and discuss the causes and management of cancer-related stroke