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School of Physics & Astronomy Institute for Condensed Matter & Complex Systems Hard, soft and biological matter. Experiment, theory, simulation working together Interdisciplinarity Themes: Hard: extreme conditions Soft: model systems Biological: multiscale. seek. locate. elucidate.
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School of Physics & Astronomy Institute for Condensed Matter & Complex Systems Hard, soft and biological matter Experiment, theory, simulation working together Interdisciplinarity Themes: Hard: extreme conditions Soft: model systems Biological: multiscale
seek locate elucidate Making high-purity single crystals of new materials State of the art low-temperature measurements at extreme conditions (10mK, 17 T, 10 GPa, two-axis rotation) Low temperature measurements and experiments at central facilities ISIS(UK), FRM2 (Ger), LLB (Fra), ILL (Fra) Quantum Ordering: Looking for new electronic states of matter Mapping the Phase diagram of YbNiSn Neutron Scattering at ILL Growing UGe2
Black Li 125GPa Transparent hP4 178GPa Shiny oP8 122GPa Black tI19 128GPa “Metals” at Extremes: Transparent Sodium & Black Lithium PNAS104, 17297 (2007); Science 320, 1054 (2008); PRB79, 064105 (2009) Lithium is a black semiconductor above 100GPa. We have grown single crystals & are determining atomic structure at ESRF. Melting T of sodium at 118GPa is just 305K. Minimum is associated with 6 complex phases. Reflected light Reflected light Transmitted light Detailed study at Diamond and ESRF (High-P Na was first paper from Diamond) Further compression of shiny metallic Na leads first to dark semimetal and then to transparent insulator at ~180GPa
Mode coupling theory • Advection of modes of density fluctuation • The only ab initio theory of colloid rheology Understanding the flow of concentrated suspensions Rewrites the textbooks Unique imaging under flow PRL (2007) (Prog Grant + NSF/EPSRC Materials) PRL (2007) • Flow profile in capillary ≠ ‘yield stress fluid’ • Instabilities induced by confinement • Implications for microfluidics of suspensions PRL (2007, 2008) • Knowledge transfer & commercialisation • EPSRC Follow-on grant for imaging module • Exploring application to chocolate • (Please don’t tell anyone!!)
Bijels: a new soft solid Bicontinuous Interfacially Jammed Emulsion Gel FUNDING ROUTE A BIJEL (Simulation) Science (2005) A BIJEL (Confocal) Nature Materials (2007) EPSRC Programme grant (including computer simulations) EPSRC Follow on fund Scottish Enterprise PoC Motor particles water oil STRUCTURE AND FORMATION Bijels are gels comprising bicontinuous water and oil domains. Bicontinuous structure formed by the arrest of (spinodal) phase separation by interfacially trapped particles. Encapsulation of bijel in Pickering droplets (bijel capsules). APPLICATIONS Delivery of incompatible ingredients (e.g. sun cream) Triggered release (T sensitive) Controlled delivery of components (e.g. toothpaste) Unique sensory properties (skin, hair) Unique spreading properties Solar cells Designer interfacial electro-optical properties A BIJEL CAPSULE
Protein self-assembly: nanomaterials, cataract, foodstuffs, and beyond EPSRC Programme Grant & EPSRC-funded studentships A mouse eye lens shows inappropriate protein self-assembly leading to heritable cataract AFM image of self-assembled protein fibres Protein self-assembly mechanism EMBO J (2002) 21: 6005-6014 A laboratory-produced pickled egg made up of self-assembled proteins: transparent, robust, and stable for weeks An understanding of the physics driving biological self-assembly underpins our knowledge of disease, the development of new materials, and inspires (bio)nanotechnology. Adding fluorophores yields self-assembled light-harvesting (bio)nanofibres for optoelectronics MacPhee Group, Physics and Life Sciences J Am Chem Soc. (2009) 131: 12520-1 Soft Matter (2009) 5: 2725-2730
Bacteria Physics: from cells to ecosystems • New methods to measure • swimming speed u • body rotation rate W • flagella rotation rate w • averaged over ~ 4000 bugs in < 2 minutes Non-monotonic dependence of u on concentration in polymer solutions E. Coli motility [Programme Grant + Senior Fellowship + RSE fellowship] Theory and simulations Predict? Spread of neolithic farming Extract DNA Wider programme on the statistical physics of interacting agents: trees, farmers, etc. [EPSRC NANIA, etc.] Denaturing Gradient Gel Electrophoresis (DGGE) Community structure Pond mud = microbial ecosystem [Leverhulme + Programme Grant] PNAS