ORCID Profile
0000-0002-8501-1344
Current Organisation
University of Sydney
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In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Interdisciplinary Engineering | Nanotechnology | Fluidization And Fluid Mechanics | Heat And Mass Transfer Operations | Computational Fluid Dynamics | Membrane and Separation Technologies | Chemical Engineering | Biochemistry and Cell Biology not elsewhere classified | Biological Physics
Industrial instrumentation | Medical instrumentation | Scientific instrumentation | Processed Milk and Cream (incl. Powder, Evaporated and Condensed) | Human Pharmaceutical Products not elsewhere classified | Management of Water Consumption by Manufacturing Activities | Concentrating Processes of Base Metal Ores (excl. Aluminium and Iron Ores) | Diagnostics | First Stage Treatment of Ores and Minerals not elsewhere classified | Expanding Knowledge in the Medical and Health Sciences |
Publisher: Elsevier BV
Date: 11-2006
Publisher: Elsevier BV
Date: 12-2010
Publisher: Elsevier BV
Date: 2012
DOI: 10.1016/J.JCIS.2011.07.078
Abstract: A mathematical framework for analysing electrokinetic flow in microchannel networks is outlined. The model is based on conservation of volume and total charge at network junctions, but in contrast to earlier theories also incorporates conservation of ion charge there. The model is applied to mixed pressure-driven/electro-osmotic flows of binary electrolytes through homogeneous microchannels as well as a 4:1:4 contraction-expansion series network. Under conditions of specified volumetric flow rate and ion currents, non-linear steady-state phenomena may arise: when the direction of the net co-ion flux is opposite to the direction of the net volumetric flow, two different fully developed, steady-state flow solutions may be obtained. Model predictions are compared with two-dimensional computational fluid dynamics (CFD) simulations. For systems where two steady states are realisable, the ultimate steady behaviour is shown to depend in part upon the initial state of the system.
Publisher: Elsevier BV
Date: 02-2017
Publisher: Elsevier BV
Date: 2012
DOI: 10.1016/J.JCIS.2011.07.076
Abstract: Existing microfluidic circuit theories consider conservation of volume and conservation of total charge at each channel intersection (node) that exists within a circuit. However, in a strict sense conservation of number (or charge) for each ion species that is present should also be applied. To be able to perform such a conservation the currents due to the movement of each ion species (electrokinetic ion currents) that occur within each channel need to be known. Hence, we here present analytical and numerical methods for calculating these ion currents (and fluid flowrates) in Newtonian binary electrolyte solutions flowing within two-dimensional thin slits and pipes. Analytical results are derived in the limits of low potential, high potential, and thin double layers. We show that irrespective of double layer overlap, the Boltzmann distribution is valid provided that a local geometric mean is used for the reference ion concentration. While the real significance of the work lies in its application to multi-channel microfluidic circuit theory (see the accompanying paper of Biscombe et al. [1]), the present results show that even in single channels, ion current behaviour can be surprisingly complex.
Publisher: Elsevier BV
Date: 03-2015
Publisher: Elsevier BV
Date: 10-2006
Publisher: Springer Science and Business Media LLC
Date: 30-09-2013
Publisher: Elsevier BV
Date: 09-2014
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6SM00047A
Abstract: Using a recently developed multiphase electrokinetic model, we simulate the transient electrohydrodynamic response of a liquid drop containing ions, to both small and large values of electric field. The temporal evolution is found to be governed primarily by two dimensionless groups: (i) Ohnesorge number (Oh), a ratio of viscous to inertio-capillary effects, and (ii) inverse dimensionless Debye length (κ), a measure of the diffuse regions of charge that develop in the drop. The effects of dielectric polarization dominate at low Oh, while effects of separated charge gain importance with increase in Oh. For small values of electric field, the deformation behaviour of a drop is shown to be accurately described by a simple analytical expression. At large electric fields, the drops are unstable and eject progeny drops. Depending on Oh and κ this occurs via dripping or jetting the regime transitions are shown by a Oh-κ phase map. In contrast to previous studies, we find universal scaling relations to predict size and charge of progeny drops. Our simulations suggest charge transport plays a significant role in drop dynamics for 0.1 ≤ Oh ≤ 10, a parameter range of interest in microscale flows.
Publisher: Elsevier BV
Date: 08-2006
Publisher: Elsevier BV
Date: 09-2002
Publisher: International Information and Engineering Technology Association
Date: 31-03-2016
Publisher: Elsevier BV
Date: 05-2007
Publisher: Springer Science and Business Media LLC
Date: 26-03-2020
DOI: 10.1038/S41598-020-62297-0
Abstract: Shear induced particle pressure occurs in concentrated suspensions of particles. Importantly, the significance of the shear induced particle pressure has not been recognized in polymer rheology. The shear induced particle pressure results in an inward pressure on the polymer chains resulting in a shear dependent compressive force. The analytical form of the force balance equations that incorporate the effect of shear induced particle pressure predict a reduced polymer blob size and reducing viscosity with increasing shear rate as has been observed experimentally. Power law behavior is found for the viscosity in accord with the general observations for concentrated polymer rheology.
Publisher: Elsevier BV
Date: 07-2008
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4LC00504J
Abstract: Concentration gradient focusing and separation in a silica nanofluidic channel with a non-uniform electroosmotic flow.
Publisher: Elsevier BV
Date: 10-2006
Publisher: Elsevier BV
Date: 10-2013
Publisher: WIT Press
Date: 19-04-2006
DOI: 10.2495/AFM06008
Publisher: Elsevier BV
Date: 08-2016
DOI: 10.1016/J.CIS.2016.05.001
Abstract: The manipulation of biomolecules, fluid and ionic current in a new breed of integrated nanofluidic devices requires a quantitative understanding of electrokinetics at the silica/water interface. The conventional capacitor-based electrokinetic Electric Double Layer (EDL) models for this interface have some known shortcomings, as evidenced by a lack of consistency within the literature for the (i) equilibrium constants of surface silanol groups, (ii) Stern layer capacitance, (iii) zeta (ζ) potential measured by various electrokinetic methods, and (iv) surface conductivity. In this study, we consider how the experimentally observable viscoelectric effect - that is, the increase of the local viscosity due to the polarisation of polar solvents - affects electrokinetcs at the silica/water interface. Specifically we consider how a model that considers viscoelectric effects (the VE model) performs against two conventional electrokinetic models, namely the Gouy-Chapman (GC) and Basic Stern capacitance (BS) models, in predicting four fundamental electrokinetic phenomena: electrophoresis, electroosmosis, streaming current and streaming potential. It is found that at moderate to high salt concentrations (>5×10(-3)M) predictions from the VE model are in quantitative agreement with experimental electrokinetic measurements when the sole additional adjustable parameter, the viscoelectric coefficient, is set equal to a value given by a previous independent measurement. In contrast neither the GS nor BS models is able to reproduce all experimental data over the same concentration range using a single, robust set of parameters. Significantly, we also show that the streaming current and potential in the moderate to high surface charge range are insensitive to surface charge behaviour (including capacitances) when viscoelectric effects are considered, in difference to models that do not consider these effects. This strongly questions the validity of using pressure based electrokinetic experiments to measure surface charge characteristics within this experimentally relevant high pH and moderate to high salt concentration range. At low salt concentrations (<5×10(-3)M) we find that there is a lack of consistency in previously measured channel conductivities conducted under similar solution conditions (pH, salt concentration), preventing a conclusive assessment of any model suitability in this regime.
Publisher: Wiley
Date: 28-01-2014
Publisher: Elsevier BV
Date: 03-2014
Publisher: No publisher found
Date: 2017
Publisher: Elsevier BV
Date: 07-2001
Publisher: Cambridge University Press (CUP)
Date: 12-2015
Abstract: Objectives: (1) Examine the opportunities young people with acquired brain injury (ABI) have to make everyday choices after moving out of residential aged care (RAC) into community-based shared supported accommodation (SSA) (2) Compare everyday choice making of this group with a group of people with ABI living in RAC. Research design: Mixed methods comparing two independent groups. Method and procedures: Responses on eleven relevant items of the Resident Choice Scale (RCS) were compared between two groups 45 people with ABI living in RAC and 20 people with ABI who had moved from RAC to live in SSA. In addition, the choice making experiences of the SSA group were investigated through semi-structured interviews with the in idual and/or their family member. Interviews were recorded, transcribed and thematically analysed. Results: Greater opportunities for everyday choice making were demonstrated on 10 out of the 11 RCS items for people living in SSA, compared to RAC. These included improved choice regarding meals, bedtime and leisure activities. Qualitative data also illustrated new choice opportunities afforded to the SSA group. Five key themes relating to choice were identified: rules and routines, communication, things to do, food and home-like environment . Conclusions: Community-based, age-appropriate and small-scale supported accommodation provides people with ABI more opportunities for everyday choice making than RAC.
Publisher: NeuroQuantology Journal
Date: 2018
Publisher: ASMEDC
Date: 2008
Abstract: Pressure drop and electroviscous effects in the axisymmetric, steady, fully developed, pressure-driven flow of incompressible power-law fluids through a cylindrical microchannel at low Reynolds number (Re = 0.01) have been investigated. The Poisson-Boltzmann equation (describing the electrical potential) and the momentum equations in conjunction with electrical force and power-law fluid rheology have been solved numerically using the finite difference method. The pipe wall is considered to have uniform surface charge density (S = 4) and the liquid is assumed to be a symmetric electrolyte solution. In particular, the influence of the dimensionless inverse Debye length (K = 2, 20) and power-law flow behaviour index (n = 0.2, 1, 1.8) on the EDL potential, ion concentrations and charge density profiles, induced electrical field strength, velocity and viscosity profiles and pressure drop have been studied. As expected, the local EDL potential, local charge density and electrical field strength increases with decreasing K and/or increasing S. The velocity profiles cross-over away from the charged pipe wall with increasing K and/or decreasing n. The maximum velocity at the center of the pipe increases with increasing n and/or increasing S and/or decreasing K. The shear-thinning fluid viscosity is strongly dependent on K and S, whereas the shear-thickening viscosity is very weakly dependent on K and S. For fixed K, as the fluid behaviour changes from Newtonian (n = 1) to shear-thinning (n & 1), the induced electrical field strength increases and maximum velocity reduces. On the other hand, the change in fluid behaviour from Newtonian (n = 1) to shear-thickening (n & 1) decreases the electrical field strength and increases the maximum velocity. The non-Newtonian effects on maximum velocity and pressure drop are stronger in shear-thinning fluids at small K and large S, the shear-thickening fluids show opposite influence. Electroviscous effects enhance with decreasing K and/or increasing S. The electroviscous effects show complex dependence on the non-Newtonian tendency of the fluids. The shear-thickening (n & 1) fluids and/or smaller K show stronger influence on the pressure drop and thus, enhance the electroviscous effects than that in shear-thinning (n & 1) fluids and/or large K where EDL is very thin.
Publisher: WIT Press
Date: 07-2014
DOI: 10.2495/AFM140181
Publisher: American Physical Society (APS)
Date: 08-04-2014
Publisher: Elsevier BV
Date: 08-2009
Publisher: Springer Science and Business Media LLC
Date: 10-06-2012
Publisher: American Physical Society (APS)
Date: 15-10-2014
Publisher: ASME International
Date: 13-11-2001
DOI: 10.1115/1.1370519
Publisher: Wiley
Date: 2001
DOI: 10.1002/1097-0363(20010130)35:2<151::AID-FLD87>3.0.CO;2-4
Publisher: Elsevier BV
Date: 11-2020
Publisher: Elsevier BV
Date: 07-2020
Publisher: Elsevier BV
Date: 04-2001
Publisher: Springer Science and Business Media LLC
Date: 30-09-2013
Publisher: Cambridge University Press (CUP)
Date: 08-10-2020
DOI: 10.1017/JFM.2020.662
Publisher: Elsevier BV
Date: 2014
Publisher: American Chemical Society (ACS)
Date: 13-09-2017
Publisher: Elsevier BV
Date: 11-2008
Publisher: Wiley
Date: 12-03-2019
DOI: 10.1002/NME.6037
Publisher: Elsevier BV
Date: 08-2007
Publisher: Elsevier BV
Date: 07-2000
Publisher: American Chemical Society (ACS)
Date: 14-08-2014
DOI: 10.1021/AC501875U
Abstract: Isoelectric focusing of proteins in a silica nanofluidic channel filled with citric acid and disodium phosphate buffers is investigated via numerical simulation. Ions in the channel migrate in response to (i) the electric field acting on their charge and (ii) the bulk electroosmotic flow (which is directed toward the cathode). Proteins are focused near the low pH (anode) end when the electromigration effect is more significant and closer to the high pH (cathode) end when the electroosmotic effect dominates. We simulate the focusing behavior of Dylight labeled streptavidin (Dyl-Strep) proteins in the channel, using a relationship between the protein's charge and pH measured in a previous experiment. Protein focusing results compare well to previous experimental measurements. The effect of some key parameters, such as applied voltage, isoelectric point (pI), bulk pH, and bulk conductivity, on the protein trapping behavior in a nanofluidic channel is examined.
Publisher: Cambridge University Press (CUP)
Date: 25-03-2021
DOI: 10.1017/JFM.2021.138
Publisher: American Physical Society (APS)
Date: 06-07-2015
Publisher: American Chemical Society (ACS)
Date: 29-04-2014
DOI: 10.1021/LA500206B
Abstract: Previous work has demonstrated the simultaneous concentration and separation of proteins via a stable ion concentration gradient established within a nanochannel (Inglis Angew. Chem., Int. Ed. 2001, 50, 7546-7550). To gain a better understanding of how this novel technique works, we here examine experimentally and numerically how the underlying electric potential controlled ion concentration gradients can be formed and controlled. Four nanochannel geometries are considered. Measured fluorescence profiles, a direct indicator of ion concentrations within the Tris-fluorescein buffer solution, closely match depth-averaged fluorescence profiles calculated from the simulations. The simulations include multiple reacting species within the fluid bulk and surface wall charge regulation whereby the deprotonation of silica-bound silanol groups is governed by the local pH. The three-dimensional system is simulated in two dimensions by averaging the governing equations across the (varying) nanochannel width, allowing accurate numerical results to be generated for the computationally challenging high aspect ratio nanochannel geometries. An electrokinetic circuit analysis is incorporated to directly relate the potential drop across the (simulated) nanochannel to that applied across the experimental chip device (which includes serially connected microchannels). The merit of the thick double layer, potential-controlled concentration gradient as a particle focusing and separation tool is discussed, linking this work to the previously presented protein trapping experiments. We explain why stable traps are formed when the flow is in the opposite direction to the concentration gradient, allowing particle separation near the low concentration end of the nanochannel. We predict that tapered, rather than straight nanochannels are better at separating particles of different electrophoretic mobilities.
Publisher: Elsevier BV
Date: 07-2001
Publisher: Elsevier BV
Date: 06-2017
Publisher: Elsevier BV
Date: 02-2016
Publisher: AIP Publishing
Date: 12-10-2011
DOI: 10.1063/1.3645194
Abstract: The electroviscous flow at low Reynolds number through a two-dimensional slit contraction with electric double-layer overlap is investigated numerically for cases where the permittivity of the wall material is significant in comparison with the permittivity of the liquid. The liquid-solid interface is assumed to have uniform surface-charge density. It is demonstrated that a finite wall permittivity has a marked effect on the distribution of ions in and around the contraction, with a significant build-up of counter-ions observed at the back-step. The development length of the flow increases substantially as the wall permittivity becomes significant, meaning that the electric double-layers require a longer distance to develop within the contraction. Consequently, there is a corresponding decrease in the hydrodynamic and electro-potential resistance caused by the contraction. The effect of wall-region width on the flow characteristics is also quantified, demonstrating that the development length increases with increasing wall-region width for widths up to 5 channel widths.
Start Date: 2011
End Date: 2014
Funder: Australian Research Council
View Funded ActivityStart Date: 06-2006
End Date: 12-2009
Amount: $210,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 02-2010
End Date: 12-2013
Amount: $270,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 10-2003
End Date: 10-2006
Amount: $193,035.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2016
End Date: 12-2019
Amount: $420,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 12-2016
End Date: 12-2021
Amount: $420,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 03-2012
End Date: 06-2016
Amount: $300,000.00
Funder: Australian Research Council
View Funded Activity