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McNally D.J.,New Museums Site | McNally D.J.,Protein Sciences Corporation | Darling D.,King's College London | Farzaneh F.,King's College London | And 2 more authors.
Journal of Chromatography A | Year: 2014

The ability of an anion exchange membrane to purify a γ-retrovirus was assessed and optimised with respect to different loading and wash buffers. Recoveries of infectious virus greater than 50% were consistently obtained, while specific titre was increased up to one thousand fold when compared to the material loaded. Specific proteins removed and retained by this optimised process were identified by mass spectrometry. It was possible to successfully bind and elute the equivalent of 1.27×108Ifu/ml of ion exchange membrane. This could then be highly concentrated, with infectious virus concentrated to a maximum of 420-fold compared to the load. © 2014 The Authors.


Elvira K.S.,ETH Zurich | Wootton R.C.R.,ETH Zurich | Reis N.M.,Loughborough University | Mackley M.R.,New Museums Site | DeMello A.J.,ETH Zurich
ACS Sustainable Chemistry and Engineering | Year: 2013

Singlet oxygen, a reactive oxygen species, has been a basic synthetic tool in the laboratory for many years. It can be generated either through a chemical process or most commonly via a photochemical process mediated by a sensitizing dye. The relative paucity of singlet oxygen employment in fine chemical industrial settings can be attributed to many factors, not least the requirement for excessive quantities of oxygenated organic solvents and the dangers that these represent. Microcapillary films (MCFs) are comprised of multiple parallel channels embedded in a plastic film. In this study, MCFs are employed as flow reactor systems for the singlet oxygen mediated synthesis of ascaridole. No gaseous oxygen is supplied directly to the reaction, rather mass transport occurs exclusively through the reactor walls. The rate of production of ascaridole was found to be strongly dependent on the partial pressure of oxygen present within the reaction system. This methodology significantly simplifies reactor design, allows for increased safety of operation, and provides for space-time yields over 20 times larger than the corresponding bulk synthesis. © 2013 American Chemical Society.


Magens O.M.,New Museums Site | Ishiyama E.M.,IHS Downstream Research | Wilson D.I.,New Museums Site
Applied Thermal Engineering | Year: 2016

Fouling is a chronic problem in many heat transfer systems and leads to regular cleaning of heat exchangers. Antifouling coatings are one mitigation option: The financial attractiveness of installing a coated exchanger depends on trade-offs between capital and operating costs over the lifetime of the unit. Such considerations effectively set bounds on the price of coatings, bounded by manufacturing costs and the maximum saving that can be achieved from fouling mitigation, in a 'value pricing' calculation. The 'value pricing' concept is considered here, for the first time, for heat exchangers subject to asymptotic fouling. An explicit solution to the cleaning scheduling optimisation problem is presented for the case of equal heat capacity flow rates in a counter-current single phase exchanger. A case study is used to illustrate the concepts and key learnings. A sensitivity analysis identifies scenarios where the use of antifouling coatings may be attractive, and also where there is no financial benefit in cleaning a fouled exchanger. © 2016 Elsevier Ltd. All rights reserved.


Chesterton A.K.S.,New Museums Site | Moggridge G.D.,New Museums Site | Sadd P.A.,Premier Foods | Wilson D.I.,New Museums Site
Journal of Food Engineering | Year: 2011

The shear rate experienced by a fluid near the wall of a planetary mixer when agitated by a wire whisk tool has been estimated using a simple geometrical analysis. The bowl and whisk geometries were measured for a Kenwood KM250 and a Hobart N50 mixer which are in widespread use in domestic and laboratory installations. The shear rate is shown to be a maximum at the bowl wall. This value is relatively uniform over a large fraction of the wall height, except for a small volume near the base and the region above the maximum width of the mixer. The shear rate profile is sensitive to the vertical positioning of the agitator within the bowl. For standard manufacturer speed settings, the range of maximum shear rates was estimated to be 100-500 s-1 in the Hobart and 20-100 s-1 in the Kenwood. © 2011 Elsevier Ltd. All rights reserved.


Gordon P.W.,New Museums Site | Brooker A.D.M.,Procter and Gamble | Chew Y.M.J.,New Museums Site | Wilson D.I.,New Museums Site | York D.W.,Procter and Gamble
Measurement Science and Technology | Year: 2010

Fluid dynamic gauging (FDG) is a technique for measuring the thickness of soft solid deposit layers immersed in a liquid environment, in situ and in real time. This paper details the performance of a novel automated, scanning FDG probe (sFDG) which allows the thickness of a sample layer to be monitored at several points during an experiment, with a resolution of ±5 μm. Its application is demonstrated using layers of gelatine, polyvinyl alcohol (PVA) and baked tomato purée deposits. Swelling kinetics, as well as deformation behaviour-based on knowledge of the stresses imposed on the surface by the gauging flow-can be determined at several points, affording improved experimental data. The use of FDG as a surface scanningb technique, operating as a fluid mechanical analogue of atomic force microscopy on a millimetre length scale, is also demonstrated. The measurement relies only on the flow behaviour, and is thus suitable for use in opaque fluids, does not contact the surface itself and does not rely on any specific physical properties of the surface, provided it is locally stiff. © 2010 IOP Publishing Ltd.


Wilson D.I.,New Museums Site | Rough S.L.,New Museums Site
Canadian Journal of Chemical Engineering | Year: 2012

The multi-phase nature of granular pastes, coupled with their non-Newtonian rheology and inherent inhomogeneity, makes characterisation and prediction of flow behaviour challenging. We focus on 'stiff' pastes which can maintain their shape after extrusion. We describe how the approach presented by Benbow and Bridgwater can be used to predict the deformation and flow behaviour of such materials. Illustrations are drawn from industrial pastes and applications studied in our group. Its basis in viscoplasticity and pure plasticity is discussed. Problems associated with 'stiff' pastes are highlighted. Finally, a roadmap is presented summarising how we think the progress of paste understanding needs to be developed. © 2011 Canadian Society for Chemical Engineering.


Salley B.,New Museums Site | Gordon P.W.,New Museums Site | McCormick A.J.,New Museums Site | Fisher A.C.,New Museums Site | Wilson D.I.,New Museums Site
Biofouling | Year: 2012

A new configuration of the fluid dynamic gauging technique for measuring soft layers on surfaces was used to monitor the growth of a cyanobacterium, Synechococcus sp. WH 5701, on stainless steel (SS), glass and an indium tinoxide (ITO) on a polyethylene terephthalate (PET) substratum. The biofilm thickness increased steadily over 4weeks and exhibited noticeable changes in microstructure and strength. The biofilms all exhibited a two-layer structure, with a compact layer next to the substratum and a loose layer above. Biofilms on ITO or SS exhibited cohesive failure when removed by fluid shear whereas those on glass exhibited adhesive failure. The technique is able to elucidate various aspects of biofilm behaviour, as illustrated by the action of a biocide (NaOCl) on a mature biofilm. © 2012 Copyright Taylor and Francis Group, LLC.


Pogiatzis T.,New Museums Site | Ishiyama E.M.,New Museums Site | Paterson W.R.,New Museums Site | Vassiliadis V.S.,New Museums Site | Wilson D.I.,New Museums Site
Applied Energy | Year: 2012

Fouling of heat exchangers causes reduced heat transfer and other penalties. Regular cleaning represents one widely used fouling mitigation strategy, where the schedule of cleaning actions can be optimised to minimise the cost of fouling. This paper investigates, for the first time, the situation where there are two cleaning methods available so that the mode of cleaning has to be selected as well as the cleaning interval. Ageing is assumed to convert the initial deposit, labelled 'gel', into a harder and more conductive form, labelled 'coke', which cannot be removed by one of the cleaning methods. The second method can remove both the gel layer and the coke layer, but costs more and requires the unit to be off-line longer for cleaning. Experimental data demonstrating the effects of ageing are presented. The industrial application is the comparison of cleaning-in-place methods with off-line mechanical cleaning. A process model is constructed for an isolated counter-current heat exchanger subject to fouling, where ageing is described by a simple two-layer model. Solutions generated by an NLP-based approach prove to be superior to a simpler heuristic. A series of case studies demonstrate that combinations of chemical and mechanical cleaning can be superior to mechanical cleaning alone for certain combinations of parameters. © 2011 Elsevier Ltd.


Lister V.Y.,New Museums Site | Lucas C.,New Museums Site | Gordon P.W.,New Museums Site | Chew Y.M.J.,New Museums Site | Wilson D.I.,New Museums Site
Journal of Membrane Science | Year: 2011

The build-up of particulate cake layers on porous surfaces such as those arising in cross flow microfiltration has been investigated using a new mode of operation of the fluid dynamic gauging (FDG) technique reported by Chew et al. [1]. FDG was used to track, in situ and in real time, the build-up of a filter cake during microfiltration of a suspension using pressure mode FDG, which is shown to give comparable results to conventional FDG (where the amount of liquid withdrawn from the system may vary). Validations of pressure mode FDG are reported, alongside a short demonstration study using mixed cellulose ester membranes and glass ballotini suspensions. Measurements of changes in permeate flux allowed the cake resistance to be calculated and the thickness of the cake estimated: these results gave good agreement with the FDG measurements. Computational fluid dynamics (CFD) simulations of the flow in the duct, in the gauge, and across the membrane and were performed to elucidate the flow patterns and stresses imposed on the surface being gauged. The flows were in the laminar or inertial regime, and the simulations gave good agreement with experimental measurements. The scope for using pressure mode FDG for studying fouling and cleaning in membrane modules operating at higher pressures is established. © 2010 Elsevier B.V.


Wang S.,New Museums Site | Wilson D.I.,New Museums Site
Industrial and Engineering Chemistry Research | Year: 2015

A benchtop fluid-dynamic gauging device to study the swelling or shrinking of soft solid layers immersed in a liquid environment in situ and in real time is demonstrated. A particular feature is that the volume of liquid is isolated, hence the name zero-net-discharge fluid-dynamic gauging (ZFDG), which renders ZFDG suitable for aseptic operation. For the 1.78 mm nozzle diameter used here, calibration tests gave a resolution of ±5 ∼m and an uncertainty of ±10 ∼m. Computational fluid dynamics simulations indicated that the shear stress imposed on a layer being gauged differed between the successive suction and ejection stages in ZFDG. The swelling of poly(vinyl acetate) (PVA) layers (about 1 mm dry thickness) and gelatin films (50-80 ∼m dry thickness) in aqueous solutions is reported as a demonstration of ZFDG application. There was good agreement with more cumbersome gravimetric methods. The gelatin swelled noticeably faster at high pH, above the pKa values of proline and hydroxyproline. Fitting the gelatin swelling data to a power law model indicated sub-Fickian behavior with a diffusion index that increased with the pH. © 2015 American Chemical Society.

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