Physical Sciences Colloquia
The Physical Sciences Colloquia are intended for a broad audience – from undergraduate students to retired professors. The topics encompass the interests of all research groups in the School: from Applied Optics, through Astrophysics, Planetary Science and Forensic Imaging to Functional Materials Physics and Chemistry.
The colloquia are held on Wednesdays at 2 pm in the Ingram Lecture Theatre (ILT) unless otherwise specified. The programme is constantly updated. Click on the speaker’s name and the talk’s title for biographical information/contact details and an abstract, respectively.
All our colloquia for this term will be on our Events Calendar which we regularly update when we have a confirmed speaker so make sure to check back regularly! You can also have a look at speakers for our present term by clicking on their entry below:
21st June 2018 – Kevin K. Tsia, Department of Electrical & Electronic Engineering, The University of Hong Kong
All-optical laser-scanning imaging cytometry for ultralarge-scale deep single-cell image-based analysis
Studying cell populations, their transition states and functions at the single cell level is critical for understanding in normal tissue development and pathogenesis of disease. However, current platforms for single-cell analysis (SCA) lack the practical combination of throughput and precision that is limited by the prohibitive costs and time in performing SCA, very often involving thousands to millions individual cells – largely explaining the limited applications of SCA to date. For creating new scientific insights and enriching the diagnostic toolsets, it is valuable to explore alternative biomarkers, notably biophysical markers, which maximizes the cost-effectiveness of SCA because of its label-free nature. Also, as it is closely tied with many cellular behaviours, biophysical markers can complement and correlate with the information retrieved by existing biochemical markers with high statistical precision – providing a comprehensive catalogue of single-cell properties and thus a new landscape of “Cell Altas”.
Optical microscopy is an effective tool to visualize cells with high spatiotemporal resolution. However, its full adoption for high-throughput SCA has been hampered by the intrinsic speed limit imposed by the prevalent image capture strategies, which involve the laser scanning technologies (e.g. galvanometric mirrors), and/or the image sensors (e.g. CCD and CMOS). The laser scanning speed is fundamentally limited by the mechanical inertia of the mirrors whereas the image capture rate of CCD/CMOS sensor is fundamentally limited by the required image sensitivity. Notably, this speed-versus-sensitivity trade-off of the image sensor explains why the throughput of flow cytometry has to be scaled down from 100,000 cells/sec to 1,000 cells/sec when the imaging capability is incorporated.
To address these challenges, we adopt two related techniques to enable single-cell imaging with the unprecedented combination of imaging resolution and speed. Sharing a common concept of all-optical laser-scanning by ultrafast spatiotemporal encoding of laser pulses, these techniques, time-stretch imaging and free-space angular-chirp-enhanced delay (FACED) imaging enable ultrahigh-throughput single-cell imaging with multiple image contrasts (e.g. quantitative phase and fluorescence imaging) at a line-scan rate beyond 10’s MHz (i.e. an imaging throughput up to ~100,000 cells/sec). Moreover, they also enable quantification of intrinsic biophysical markers of individual cells – a largely unexploited class of single-cell signatures that is known to be correlated with the overwhelmingly investigated biochemical markers. All in all, these ultrafast single-cell imaging platforms could find new potentials in deep machine learning complex biological processes from such an enormous size of image data (from molecular signatures to biophysical phenotypes), especially to unveil the unknown heterogeneity between different single cells and to detect (and even quantify) rare aberrant cells.
20th June 2018 – Marisa Montiero, Science Museum, University of Porto
In between a science center and University historical collections: the practice of science outreach
The University of Porto was founded in 1911, having roots in two late 18th century Nautical and Drawing Classes, an early 19th century Marine and Commerce Academy, and a Polytechnic Academy created in 1837 to provide various engineering courses, in the wake of a reform of public education. Scientific instruments and models, nautical charts and didactic prints gathered along the way have come to make up some significant historical collections of the Faculty of Science.
The interest for science centers that swept across modern industrialized countries in the last decades of the past century, combined with the emergence of European funding programs to promote scientific literacy in the country, concomitantly with the transfer of the Physics and Chemistry Laboratories to new buildings, leaving behind instruments and apparatus no longer being used, led to the foundation of a Museum of Science in the University of Porto in 1996.
A two-fold mission was then assumed by the Museum of Science: on one side, to set up a permanent interactive exhibition that could both grab the attention of visitors who have not learned much about Science (namely Physics), and give school groups the opportunity to observe and become involved with experiments that might help to understand otherwise hard to grasp physics concepts; on the other side, to restore, preserve and study the historical instruments, models, drawings and other related objects, showcasing them, whenever possible, in exhibitions and outreach activities.
A broad description of our work at the Museum, in the past two decades, will be given here, with special highlight to some of our challenges and achievements.
13th June 2018 – , Prof James Tucker (University of Birmingham)
Functional Derivatives and Analogues of Nucleosides and Nucleic Acids
The talk will cover our work on functionalised nucleic acid based systems. The oligomers can be tagged with fluorescent (e.g. anthracene) or redox-active (e.g. ferrocene) groups for medical sensing applications and in particular for reading out single base changes in target strands for the detection of diseases with a genetic component, e.g. cancer. The origins and reasons behind the observed sensing responses will be discussed. The talk will also cover the use of derivatives of some ferrocene tag as nucleoside mimics for use as potential organometallic anticancer agents.
30th May 2018 – Dr Elizabeth Hillard (Centre de Recherche Paul Pascal – CNRS, Bordeaux)
Recent studies on structural, magnetic and chiroptical properties of trinuclear paddlewheel complexes
Polynuclear paddlewheel complexes – also known in the literature as “extended metal atom chains”  or “metal strings”  – are examples of linear clusters characterized by their short intermetallic distances. These metal-metal interactions, often considered as formal metal-metal bonds, typically give rise to delocalized systems, where unpaired electrons are shared over all the metal sites. This feature poses a challenge in the understanding of their electronic structure, but also opens new avenues in molecular magnetism, chirality and single-molecule conductivity.
An overview of our work of the last five years in the synthesis and characterization of trinuclear paddlewheel complexes will be presented. Topic include a discussion of the unusual plasticity found in the trimetal core, and its influence on the electronic and magnetic properties of trichromium and tricobalt complexes, as well as recent work in the enantiomeric resolution of such complexes and their remarkably intense chiroptical signals [3,4].
 J. F. Berry in Multiple Bonds between Metal Atoms, 3rd ed., F.A. Cotton, C.A. Murillo, R. A. Walton, Eds., Springer: New York, NY, USA, 2005; p. 699.
 S. A. Hua, M. C. Cheng, C.-h. Chen, S.-M. Peng, Eur. J. Inorg. Chem. 2015, 2510.
 A. Srinivasan, M. Cortijo, V. Bulicanu, et al. Chem. Sci. 2018, 9, 1136.
 V. Pérez, A. Naim, E. A. Hillard, P. Rosa, M. Cortijo, Polymers 2018, 10, 311.
23rd May 2018 – Prof. Vinjanampathy, Indian Institute of Technology (IIT) Bombay,
Putting the “Quantum” in Technology
Small, commercial quantum computers are available for purchase today. Large-scale quantum computers, as well as other quantum technologies are actively being developed commercially. These technologies include quantum batteries, sensors and engines. We are developing the theoretical framework for these machines in the quantum regime and have proven that they have the ability to outperform (i.e., show a “quantum advantage” over) their classical analogues. In this colloquium-style talk, I will discuss how various quantum technologies exploit quantum correlations to achieve this advantage. I will focus on quantum batteries and quantum thermal machines as examples of technologies achieving quantum advantage, and I will explain their working principles with examples.
16th May 2018 – Prof. Dudley Shallcross (Department of Chemistry, University of Bristol) – RSC Nyholm Lecture
The myriad impacts of public engagement on tertiary education; including smoothing the transition from secondary to tertiary education
Public engagement, often referred to as Outreach, should not be an optional extra for research active staff and should not be the preserve of communication experts only. In this talk we chart the myriad impacts of public engagement following the establishment of the Bristol ChemLabS Centre for Excellence in Teaching and Learning. Crucial to the success of the Bristol ChemLabS public engagement programme was the appointment of a School Teacher Fellow (and we will discuss their impact on smoothing the transition from secondary to tertiary education) and a well-trained cadre of postgraduate (and undergraduate) students. However, the key ingredient was a proactive senior management team. Examples of impact include; direct impact on research, enhancement and improvement of teaching, the Dynamic Laboratory Manual, postgraduate employability, wider stakeholder involvement in the School of Chemistry, impact on grant success and widening the type of grants applied for and received, engaging administrative staff, national and international awards and many more.
9th May 2018 – Prof. Lewis Dartnell (Department of Life Sciences, University of Westminster)
Martian Death Rays
Cosmic radiation represents a pervasive field of energetic particles throughout the cosmos. Solar energetic particles (SEP) are produced by events like coronal mass ejections, and galactic cosmic rays (GCR) are accelerated to even higher energies by supernova throughout the galaxy. On the Earth’s surface, we are protected from this bombardment of energetic particle radiation by the geomagnetic field, and the absorbing depth of our thick atmosphere. But beyond this protective cocoon, cosmic radiation is a primary hazard to long-duration crewed space missions, as well as potential life on other planets and moons. This ionising radiation field can inactivate populations of microbial cells, and subsequently act to even erase many of the biosignatures – relic evidence of their past existence – which we may hope to detect with our exploration probes. The search for life, past or present, in the unshielded martian surface may well be frustrated by the long-term action of the cosmic radiation flux.
Lewis Dartnell is a researcher and Professor of Science Communication at the University of Westminster. His research is in the field of astrobiology and the search for microbial life on Mars, studying the survival limits of hardy ‘extremophile’ microorganisms and how best to detect them with instruments on our robotic probes. He graduated from Oxford University with a degree in Biological Sciences and completed his PhD at University College London in 2007. Alongside his research he is active in science communication, and has published four books.
28th March 2018 – Dr Tim Easun (Department of Chemistry, Cardiff University)
Dynamic behaviour in metal-organic frameworks
The primary applications of metal-organic frameworks (MOFs) are often proposed to be in gas storage and separation, and they are indeed highly promising crystalline microporous materials with potential to act as rapid uptake/release sorbents for important gases such as CO2, H2 and CH4. However, increasingly the more niche, specialised properties and functions of well-designed MOFs are gaining traction. A crucial aspect of any advanced study on MOFs is the use of a wide variety of analytical techniques to study the behaviour of both the frameworks and their guests. This talk will briefly describe examples of some of these techniques, including synchrotron-based experiments, and specifically highlight the area of photoresponsive MOFs, describing examples of the different strategies to incorporate and perhaps exploit light-induced structural changes in framework materials.
7th March 2018 – Ashley George CC FRSC (Global Head of Innovation & Consumerisation CoE, GSK)
28th Feb 2018 – Dr Karen Robertson, Max Planck Institute for Colloids and Interfaces
Crystal Flow: understanding and controlling crystalline materials; 2pm, Ingram Lecture Theatre, Ingram Building, Canterbury Campus
Crystals are used in a vast range of applications, including pharmaceuticals, smartphones and insulation, where efficiency is often related to the crystal structure. For example, when a more stable crystalline form of the HIV/AIDs drug, Ritonavir, began to appear in factories, the original and more soluble (directly related to how well it is taken up into the body) crystalline form could not be produced. This meant that it had to be removed from the market whilst a new formulation was devised.
Crystallising in flow environments can allow for control over the resultant material not achievable in standard methods.1 Flow crystallisation has seen a surge of innovation in the past five years with a range of research lab-accessible milli-scale crystallisers developed.2,3 Employing varied flow crystallisers we have accessed a range of crystal attributes such as crystalline form (polymorph), particle size and shape control.4,5
The next evolutionary step in crystallisation control has been realised in the adaptation of a bespoke liquid-segmented crystalliser (KRAIC) for in-situ X-Ray analysis on the high resolution powder beamline (I11) at Diamond Light Source. The on-line structural information gained from this platform can help us to understand the crystallisation process as it is happening and therefore design more efficient routes to more efficacious materials.
1. K. Robertson, Chemistry Central Journal, 2017, 11:4
2. A. J. Alvarez, A. S. Myerson, Crystal Growth and Design, 2010, 10, 2219-2228
3. R. J. P. Eder, S. Schrank, M. O. Besenhard, E. Roblegg, H. Gruber-Woelfler, J. G. Khinast, Crystal Growth and Design, 2012, 12, 4733-4738
4. K. Robertson, A. R. Klapwijk, P.-B. Flandrin, C. C. Wilson, Crystal Growth and Design, 2016, 14, 4759-4764
5. K. Robertson,* P.-B. Flandrin, H. J. Shepherd, C. C. Wilson, Chemistry Today, 2017, 35 (1), 19-22
7th Feb 2018 – Prof Anna Peacock, Optoelectronics Research Center (ORC), University of Southampton
Semiconductor Optical Fibres: A New Platform for Nonlinear Optics?; 2pm, Ingram Lecture Theatre, Ingram Building, Canterbury Campus
Combined OSA Student Chapter Talk/SPS Colloquium
Silicon photonics is currently one of the largest growing areas of research, attracting considerable interest amongst both academic and industrial communities. The ability to incorporate the semiconductor functionality into the optical fibre geometry provides an important step towards the seamless integration of these two technologies, as well as opening up new application areas for optical fibre systems. This seminar will review recent progress in the emerging field of semiconductor optical fibres, highlighting the different materials and novel geometries that are available through this platform. Particular focus will be placed on our effort to characterize the nonlinear optical properties of the silicon core fibres from telecoms wavelengths up to the short-wave infrared, with the results being discussed in relation to future device development.
31st Jan 2018 – Prof Andrew G. Green, London Centre for Nanotechnology
Path integrals over entangled states; 2pm, Ingram Lecture Theatre, Ingram Building, Canterbury Campus
Entanglement is fundamental to quantum mechanics. It is central to the EPR paradox and Bell’s inequality, and gives robust criteria to compress the description of quantum states. In contrast, the Feynman path integral shows that quantum transition amplitudes can be calculated by summing sequences of states that are not entangled at all. This gives a clear picture of the emergence of classical physics through the constructive interference between such sequences. Accounting for entanglement is trickier and requires perturbative and non-perturbative expansions.
We combine these two powerful and complementary insights by constructing Feynman path integrals over sequences of states with a bounded degree of entanglement. I will discuss the physical insights that such a construction affords.
17th Jan 2018 – Dr. Malte Grosche, Cavendish Laboratory, University of Cambridge
Correlated States Near Pressure-Induced Instabilities; 2pm, Ingram Lecture Theatre, Ingram Building, Canterbury Campus
Many complex materials display an interesting interplay between structural and electronic instabilities, which can be studied effectively under applied pressure. If a continuous structural phase transition is suppressed to low temperatures, as in the quasi-skutterudite system (Sr/Ca)3(Ir/Rh)4Sn13 , low-energy vibrational excitations can arise that boost superconductivity and cause a linearly temperature dependent electrical resistivity. We report that the aperiodic high-pressure host-guest structure of elemental bismuth displays a similar phenomenology, suggesting significantly enhanced phonon spectral weight at low energies.
It is increasingly desirable to probe the electronic structure near pressure-induced quantum phase transitions directly and in detail. We have observed the electronic Fermi surface on the metallic side of a Mott insulating transition by high pressure quantum oscillation measurements in NiS2 . Our results show that the Fermi surface remains large on approaching the Mott insulating state, consistent with Luttinger’s theorem, whereas the quasiparticle effective mass is strongly renormalised.
1. Goh et al. Phys. Rev. Lett. 114, 097002 (2015) 2. Friedemann et al. Sci. Rep. 6, 416 (2016)
Past speakers are on the next page.