- EaStCHEM Colloquia
- Physics and Astronomy Colloquia
- Irvine Lectures
- Photonics Seminar
- Special Seminars
- Synthesis Seminars
- Cond Mat Seminars
- Organic Semiconductor Centre
- Theoretical Physics Discussion Group
- ScotCHEM Colloquia
- History of Mathematics
- RSC Award Lectures
- Toy List
- Special Mini-Symposium - Structural Chemistry at Central Facilities
- Strong coupling seminars
Viewing upcoming talks containing the keyword: 3
Mechanistic Insights into the Structure-Property Relationship through detailed Crystallographic Studies
Speaker: Mark Senn (University of Oxford )
Engineering a ground state structure to produce a desired physical property is becoming more widespread, particularly in the field of ferroelectrics where the symmetry of the paraelectric parent phase may be intentionally broken by chemical design to lead to a polar distortion, e.g., Ref. 1. Here it is our ability to characterise the structure via crystallographic methods and qualify its average symmetry which allows us to inform the structure-property relationship which underpins this work. I will give two examples from my own research where symmetry analysis of the ground state crystallographic structure has led to mechanistic insight into metal-insulator phase transitions2 and improper ferroelectric mechanisms3.
However, despite the success of this approach, several limitations exist. Firstly, many physical properties such as thermal expansion and superconductivity do not arise solely from the ground state crystal structure but due to excitations and lattice dynamics. Secondly, not all functional materials are fully ordered and their physical properties often arise from so called order-disorder phase transitions. Here, long-range crystallographic symmetry does not reflect the local underlying microscopic mechanism, and it is unclear what insight conventional crystallography can bring. In the second half of my talk I will extend the application of symmetry analysis further to tackle these problems. I will show how we can gain insight into negative thermal expansion though the study of closely competing ground state structures3 and how in the archetypal ferroelectric Barium Titanate we can reconcile the observed order-disorder phase transitions with its long range crystallographic symmetry and its observed macroscopic properties4.
1) A. T. Mulder, N. A. Benedek, J. M. Rondinelli, C. J. Fennie, Adv. Funct. Mater. 23, 4810–4820 (2013).
2) M.S. Senn, J.P. Wright, and J.P. Attfield, Nature 481, 173 (2012).
3) M.S. Senn, A. Bombardi, C.A. Murray, C. Vecchini, A. Scherillo, X. Luo, and S.W. Cheong, Phys. Rev. Lett. 114, 23 (2015).
4) M.S. Senn, D.A. Keen, T.C.A. Lucas, J.A. Hriljac, and A.L. Goodwin, http://arxiv.org/abs/1512.03643 (2015).
On: January 22, 2016 From: 14h00 To: 15h30View talk
Speaker: Angela Russell (Oxford)
The ability to harness the potential of adult stem and precursor cells would be a major advance in the treatment of human disease. They are remarkable cells characterized by their ability to divide and to differentiate via a number of steps to embryonic and adult somatic cell lineages. Such cells thus hold enormous promise both for in vitro screening tools for drug efficacy and toxicity testing, and especially for regenerative therapies treating a wide range of disorders with high unmet medical need such as neurodegenerative diseases, diabetes, heart disease, and vision loss.
The discovery of small molecules to control cell fate has attracted immense interest in recent years. The ability to control each step in proliferation, differentiation and dedifferentiation/ reprogramming processes would allow control of the selective production of different tissue types both in vitro and, importantly in many instances, directly in vivo. The use of chemicals to manipulate cell fate offers many significant advantages over other techniques in terms of speed, cost, reproducibility and the ability to influence cell fate reversibly.
The talk will give a brief overview of the area, outline how my group became involved in the field and cover contributions we have made, particularly to induce the proliferation and differentiation of pluripotent stem cells and how we are aiming to translate our work to the clinic for regenerative therapies.
On: January 27, 2016 From: 15h30 To: 16h30View talk
Physics and Astronomy Colloquia
Speaker: Dr Paul van Kampen (Dublin City University, Centre for Laser Plasma Research)
Electromagnetism is a challenging topic to teach and to learn. For example, students often find it difficult to distinguish between force and field, to understand electromagnetic induction. It is well known that many students struggle to apply mathematics in their study of physics in general and in electromagnetism in particular.
In this talk I will outline how systematic inquiry into how students learn physics (i.e., Physics Education Research) has identified common difficulties, and I will illustrate instructional materials that help students overcome them.
On: January 29, 2016 From: 10h00 To: 11h00View talk
From Bacterial to Biomimetic Magnetosomes for Nanomedicine and Nanotechnology (Video Conference from Edinburgh)
Speaker: Sarah Staniland (Sheffield)
Magnetic nanoparticles (MNPs) have many applications, particularly over a range of emerging biomedical diagnostic and therapeutic nanomedicine such as targeted and hyperthermic drug delivery and diagnostics such as MRI contrast agents. Similarly they have high value in nanotechnologies such as ultra high-density data storage.
MNPs often require a mono-disperse size and shape distribution to ensure their magnetic behaviour is consistent, which can require chemical synthesis under harsh conditions.
Magnet bacteria synthesis nanoparticles of magnetite within lipid vesicles (known as magnetosomes) within their cells. These precise magnetosomes can be extracted and used for various biomedical applications, but their properties are restricted to the natural form, limiting their applications.
In this talk I will show 1) how we can alter the magnetosomes in vivo to produce enhanced MNPs for a range of biomedicine, 2) Utilise key biomineralisation proteins from the bacteria in vitro as an additive to control the of MNPs in a “green” chemical precipitation. 3) Utilise novel methods of developing new protein additives to control the shape of MNPs via green synthesis. 4) utlise these proteins on surfaces to form precise arrays of mono-dispersed MNPs with potential application in nanotechnology and 5) Show we can biomimic the magnetosome itself to produce a completely artificial magnetosomes and hybrid magnetovesicle materials for biomedical applications.
On: February 3, 2016 From: 16h00 To: 17h00View talk
Cond Mat Seminars
Speaker: Gwendal FÃ¨ve (LPA-ENS, Paris)
Quantum effects have been studied on photon propagation in the context of quantum optics since the second half of the last century. In particular, using single photon emitters, fundamental tests of quantum mechanics were explored by manipulating single to few photons in Hanbury-Brown and Twiss and Hong Ou Mandel  experiments.
In nanophysics, there is a growing interest to translate these concepts of quantum optics to electrons propagating in nanostructures. In two-dimensional electron gases, electronic propagation can be guided along the edge channels of the quantum Hall effect and quantum point contacts can be used as electronic beam-splitters to implement electronic interferometers . Single electron emitters have also been realized such that single elementary electronic excitations can now be manipulated in the analog of pioneer quantum optics experiments. However, these electron quantum optics experiments go beyond the mere reproduction of optical setups using electron beams, as electrons, being interacting fermions, differ strongly from photons.
I will discuss in particular the electronic analog [3, 4] of the Hong-Ou-Mandel experiment where two single electrons collide on a beam-splitter. Two-particle interferences between two indistinguishable single electrons can then reveal the coherence properties of single electron states and probe how they are affected by the Coulomb interaction along propagation [5,6,7].
References: C. K. Hong, Z. Y. Ou, and L. Mandel Physical Review Letters 59, 20442046 (1987).  Y. Ji et al. Nature 422, 415–418 (2003).  S. Ol'khovskaya, J. Splettstoesser, M. Moskalets, M. Büttiker, Phys. Rev. Lett. 101, 166802 (2008).  E. Bocquillon et al., Science 339, 1054 (2013).  D. Ferraro et al., Phys. Rev. Lett. 113, 166403 (2014).  C. Wahl, J. Rech, T. Jonckheere, T. Martin, Phys. Rev. Lett. 112, 046802 (2014).  V. Freulon et al., Nat. Commun. 6, 6854 (2015).
On: February 3, 2016 From: 13h00 To: 14h00View talk
Physics and Astronomy Colloquia
Speaker: Dr Ruth Oulton (University of Bristol, Centre for Quantum Photonics)
Quantum dots are semiconductor artificial atoms. They are nanoscale structures that trap single electrons and holes, and their quantized energy level structure results in atomic-like transitions and single photon emission. These quantum dots act as a solid-state interface that is useful for quantum information applications, and for the past decade, semiconductor physicists have been attempting to replicate atomic cavity quantum electrodynamics in a practical semiconductor form. One can embed quantum dot into micron-sized photonic structures to capture and control the light emission, in order to use the single photon emission in quantum communication and quantum circuits.
One of the most exciting applications of quantum dots is to use their electron spins as a quantum memory. This involves transferring spin information from an electron spin to the polarization of a photon. However, as I shall explain, the definition of “polarization” for nanophotonic structures is far more complex than for a beam of light. In fact, we find that point-like “spin” emitters couple to a photonic structure in surprising ways: unlike any phenomenon observed in bulk material, simply changing the position of an emitter or the spin direction controls completely in which direction photons propagate. Suddenly, a rich variety of behaviour has arisen in the semiconductor/photonic domain which has no equivalent in atomic cavity QED, including a fundamental difference between how a classical dipole and a quantum dipole emitter interfere with incoming light. I will finally discuss progress on achieving deterministic photon-spin interactions. In particular I will demonstrate a macroscopic spin-induced phase shift in a low Q-factor system. Thus I show that when designing photonic QD systems, it is the “beta” factor, not the cavity quality (Q) factor, that should be optimised to achieve deterministic interactions.
On: February 5, 2016 From: 10h00 To: 11h00View talk