Matthew Mears
University of Sheffield
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Publication
Featured researches published by Matthew Mears.
Biochimica et Biophysica Acta | 2015
Yu Pen; Zhenyu Zhang; Ana L. Morales-García; Matthew Mears; Drew S. Tarmey; R.G.J. Edyvean; Steven A. Banwart; Mark Geoghegan
The mechanical properties of Rhodococcus RC291 were measured using force spectroscopy equipped with a bacterial cell probe. Rhodococcal cells in the late growth stage of development were found to have greater adhesion to a silicon oxide surface than those in the early growth stage. This is because there are more extracellular polymeric substances (EPS) that contain nonspecific binding sites available on the cells of late growth stage. It is found that EPS in the late exponential phase are less densely bound but consist of chains able to extend further into their local environment, while the denser EPS at the late stationary phase act more to sheath the cell. Contraction and extension of the EPS could change the density of the binding sites, and therefore affect the magnitude of the adhesion force between the EPS and the silicon oxide surface. By treating rhodococcal EPS as a surface-grafted polyelectrolyte layer and using scaling theory, the interaction between EPS and a solid substrate was modelled for the cell approaching the surface which revealed that EPS possess a large capacity to store charge. Changing the pH of the surrounding medium acts to change the conformation of EPS chains.
Macromolecular Rapid Communications | 2011
Matthew Mears; Drew S. Tarmey; Mark Geoghegan
We consider the behaviour of single molecules on surfaces and, more generally, in confined environments. These are loosely split into three sections: single molecules in biology, the physics of single molecules on surfaces and controlled (directed) diffusion. With recent advances in single molecule detection techniques, the importance and mechanisms of single molecule processes such as localised enzyme production and intracellular diffusion across membranes has been highlighted, emphasising the extra information that cannot be obtained with techniques that present average behaviour. Progress has also been made in producing artificial systems that can control the rate and direction of diffusion, and because these are still in their infancy (especially in comparison to complex biological systems), we discuss the new physics revealed by these phenomena.
Macromolecules | 2018
Zhenyu J. Zhang; Steve Edmondson; Matthew Mears; Jeppe Madsen; Steven P. Armes; Graham J. Leggett; Mark Geoghegan
The diffusion of rhodamine-labeled poly(ethylene glycol) (r-PEG) within surface-grafted poly(ethylene glycol) (s-PEG) layers in aqueous solution at 18 °C was measured by fluorescence correlation spectroscopy. The diffusion coefficient of r-PEG within s-PEG was controlled by the grafting density, σ, and scaled as σ–1.42±0.09. It is proposed that a characteristic blob size associated with the grafted (brush) layer defines the region through which the r-PEG diffusion occurs. The diffusion coefficients for r-PEG in semidilute solution were found to be similar to those in the brushes.
American Journal of Physics | 2015
Matthew Mears
A new rolling apparatus known as the spiderwheel is described, which allows for large changes in mass distribution (and hence moment of inertia) without anything being added to or removed from the body. A quantitative analysis of the rolling spiderwheel motion allows students to determine its moment of inertia and compare it with model systems such as a rotating point mass, a solid cylinder, and a thin rigid hoop. Despite the spiderwheels complex geometry and multiple components, a simple point-mass model provides an excellent approximation.
Theriogenology | 2014
Matthew Mears; Thomas M. Kennelly; Jonathan R. Howse; Drew S. Tarmey; Mark Geoghegan; Allan A. Pacey
The curvilinear velocity (VCL) of boar spermatozoa between standard microscopy glassware decreases when the slides are coated with the hydrophobic polymer polystyrene (PS) compared with the less hydrophobic poly(methyl methacrylate) (PMMA) coating. Sperm from three boars were observed and analyzed using particle tracking software. The VCL did not differ significantly between coatings of different thickness, indicating no penetration of the sperm into the coating and that only the surface layer of the polymer film interacts with the sperm and buffer medium. The VCL of sperm between PS-coated surfaces was significantly reduced compared with PMMA surfaces (P < 0.0001), and this was attributed to a stronger hydrophobic effect between PS and water. The size of this effect varied between different boars, perhaps as a consequence of variations in hydrophobicity of sperm from different boars or different ejaculates. The modification of surface properties in this way may improve our understanding of sperm behavior and may provide improvements to assisted conception techniques as animal or human sperm used in assisted conception are frequently manipulated in laboratory plastics as part of diagnostic procedures (e.g., semen analysis) or before injection into an oocyte or during the co-incubation with the oocyte in IVF. Controlling the velocity of sperm using the interaction properties of inert polymer coatings could lead to new sperm selection procedures for clinical use or the development of model systems to better understand sperm-surface interactions.
Journal of Polymer Science Part B | 2012
Ateyyah M. AL-Baradi; Matthew Mears; Richard A. L. Jones; Mark Geoghegan
Bulletin of the American Physical Society | 2018
Eleanor Dougherty; Mark Geoghegan; Matthew Mears
European Polymer Journal | 2017
Zhenyu Zhang; Jeppe Madsen; Nicholas J. Warren; Matthew Mears; Graham J. Leggett; Andrew L. Lewis; Mark Geoghegan
New directions in the teaching of physical sciences | 2016
Matthew Mears
Bulletin of the American Physical Society | 2015
Mark Geoghegan; Matthew Mears; Christopher G. Clarkson; Zhenyu Zhang; John M. Torkelson