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Viewing upcoming talks containing the keyword: 19
Speaker: George Shimizu (University of Calgary)
Metal organic frameworks (MOFs) represent tunable molecular scaffoldings that can be adjusted for a breadth of applications. This presentation will concern our efforts towards tailoring MOFs towards two globally relevant energy challenges, CO2 capture and fuel cells.
The first topic concerns our efforts to make MOFs for gas capture. Two sub-topics will be the use of MOFs with high CO2 capture ability and efforts to generally make MOFs more robust. In contrast to liquid amines which chemisorb CO2 and have high energy costs for regeneration, the MOF approach typically gives physisorbed gases and hence more facile release. Despite the weaker binding mode, we will show that high selectivities are possible owing to heats of adsorption over 40 kJ/mol1 and cooperativity between CO2 molecules in augmenting binding.2 Related to this is the need to enhance water stability of the MOF backbone and our efforts to achieve this goal will be presented.3
The second topic concerns an approach to better proton conductors for PEM fuel cell membranes.4 A major hurdle in these technologies is an electrolyte capable of operating above 100ËšC. Higher operating temperatures will enhance electrode kinetics and decrease electrode poisoning among several critical operational benefits. In contrast to polymer approaches towards these electrolytes, we have used a MOF strategy to generate crystalline networks with acidic pores. These MOFs present options for higher temperature conduction,5 conduction over 10-2 Scm-1,6 and water stability.7,8
 R. Vaidhyanathan et al. Science, 2010, 330, 650.  R. Vaidhyanathan et al. Angew. Chem., 2012, 51, 1826.  a) J. M. Taylor et al., J. Am. Chem. Soc. 2012, 134, 14338; b) Gelfand, B. S. Dalton Trans, in press.  G. K. H. Shimizu et al. Science, 2013, 341, 354.  J. A. Hurd et al. Nature Chem. 2009, 1, 705.  S. Kim et al., J. Am. Chem. Soc. 2013, 135, 963.J. M. Taylor et al., J. Am. Chem. Soc. 2013, 135, 1193. Ramaswamy, P. et al.J. Am. Chem. Soc. 2015, 137, 7640
On: February 29, 2016 From: 11h00 To: 12h00View talk
Speaker: Prof Stephen Liddle (Manchester)
There is currently great interest in the nature and reactivity of molecular uranium-ligand multiple bonds.1 This is because the nature and extent of 5f/6d orbital participation in uranium-ligand bonding is still a topic of debate, and the unique orbital-hybridisation patterns available to uranium promises novel reactivity and magnetism. We have found that certain triamidoamine ligands are exceptionally effective at stabilising unprecedented uranium-ligand multiple bonds involving main group fragments of interest in their own right. This talk will provide an overview of our progress to date covering oxo, nitride, parent-imido, -phosphinidene, -arsinidene, and arsendio complexes, and their electronic structure, bonding, reactivity, and magnetism will be discussed. If time allows we will describe our more recent work in this area.
We gratefully acknowledge continued and generous funding by the Royal Society, European Research Council, Engineering and Physical Sciences Research Council, The University of Nottingham, The University of Manchester, UK EPSRC National EPR Facility, COST, and the UK National Nuclear Laboratory.
1. S. T. Liddle, Angew. Chem. Int. Ed. 2015, 54, 8604.
On: March 2, 2016 From: 15h30 To: 16h30View talk
Physics and Astronomy Colloquia
Speaker: Prof Kevin France (University of Colorado, Department of Astrophysical and Planetary Sciences)
The composition and spatial distribution of molecular gas in the inner few AU of young (< 10 Myr) circumstellar disks are important components to our understanding of the formation of planetary systems. In the first part of this talk, I will discuss the current, observationally-based picture of protoplanetary gas disks at r < 10 AU. I will review the most widely used spectral diagnostics of the inner disk, and highlight recent observations of H2 and CO made by the Hubble Space Telescope. I will describe how high-resolution spectroscopy is being used to constrain the composition, distribution, and evolution of molecular gas in the inner disk at spatial scales too small to resolve with current imaging instruments/facilities.
In the second part of this talk, I will discuss how the spectral and temporal behavior of exoplanet host stars is a critical input to models of the chemistry and evolution of planetary atmospheres. I will present results from a Hubble Treasury program that is currently underway to characterize the panchromatic (X-ray through mid-IR) radiation environments around low-mass host stars for the first time. We find that all exoplanet host stars observed to date exhibit significant levels of UV/X-ray activity, and that strong flares are common, even on “optically inactive” M dwarfs hosting planetary systems. I will briefly discuss the use of these data in atmospheric models of rocky planets around cool stars, including the predicted abiotic production of O2 and O3 – a cautionary tale for the interpretation of “biomarker” gases when they are detected in the coming decades.
On: March 4, 2016 From: 10h00 To: 11h00View talk
Speaker: Elena Besley (Nottingham)
There are many instances in everyday life where small particles can acquire an electrical charge of the same sign. Examples include aerosol and water droplets in clouds, dust particles in space, toner particles in ink-jet printers, and suspensions of colloidal particles. As the particles carry a charge of the same sign, either positive or negative, they are expected to repel one another; however, under certain circumstances their interaction can be strongly attractive. For conducting particles, this effect was identified by William Thomson (later Lord Kelvin) who in 1845 developed a theory showing that the attraction is due to differences in the magnitude of the image charges induced in particles in cases where either their size or charge differs.1
Until recently there was no stable mathematical solution to the fundamental problem of calculating the electrostatic interaction between charged particles of dielectric material, mainly due to significant mathematical complexity of the problem. To date a variety of solutions have been offered, many of which present mathematical derivations with limited applicability, numerical complications or poor convergence at short particle separations.
I will report a comprehensive theory2,3 with universal relevance to the electrostatic properties of closely interacting particles of arbitrary size and charge.4-7 Calculations of surface charge density provide evidence of the physical effects, which cause polarisable particles carrying the same sign of charge to attract one another. The results show that attraction requires a mutual polarisation of charge, leading to regions of negative and positive surface density, at short separation distances. In this talk, the new theory will be discussed together with its relevance across multiple disciplines involving interactions of small particles. Our explanation of how particles interact with one another may also contribute to the design of thin films and surface assemblies with novel properties.
1. Thomson, W. (Lord Kelvin), J. Math. Pures Appl., 10: 364 (1845); J. Math. Pures Appl., 12: 256 (1847)
2. Bichoutskaia E., Boatwright A. L., Khachatourian A., Stace A. J., J. Chem. Phys., 133: 024105 (2010)
3. Khachatourian, A., Chan, H.-K., Stace, A. J., Bichoutskaia, E., J. Chem. Phys., 140: 074107 (2014)
4. Stace, A. J., Boatwright, A. L., Khachatourian, A., Bichoutskaia, E., J. Coll. Inter. Sci., 354: 417 (2011)
5. Stace, A. J., Bichoutskaia, E., Phys. Chem. Chem. Phys., 13: 18339 (2011)
6. Stace, A. J., Bichoutskaia, E., Soft Matter, 8: 6210 (2012)
7. B. Lindgren, E., Chan, H.-K., Stace, A. J., Besley, E. Perspective Article, Phys. Chem. Chem. Phys.
DOI: http://dx.doi.org/10.1039/C5CP07709E (2016)
On: March 9, 2016 From: 15h30 To: 16h30View talk
Physics and Astronomy Colloquia
Speaker: Dr Gaitee Hussain (ESO)
Solar-type stars display signs of magnetic activity at all wavelengths, from energetic X-ray and UV flares to variability in photometric light curves caused by large cool spots. Several factors determine the magnetic activity level observed in all of these diagnostics; the key ones being the stellar rotation rate and the internal structure of the star. In the past two decades advances in instrumentation have facilitated the direct detection of surface magnetic fields in cool stars. Combined with powerful techniques based on medical imaging principles we can actually reconstruct the detailed surface magnetic field maps on stars covering a range of evolutionary states.
Stellar magnetic fields play a particularly important role in young stars that are only a few million years old - a key stage in a young planetary system, as this is when gas giant planets form around their host stars. I will present the latest results from our surveys of young stars, showing how the surface magnetic field properties depend on their evolutionary stages. I will also show how our detailed surface maps can be used to build realistic models of the “weather” around stars that host planetary systems, and therefore better understand the environments around which planets form and evolve.
On: March 11, 2016 From: 10h00 To: 11h00View talk
Speaker: George Malliaras (EMStE)
One of the most important scientific and technological frontiers of our time lies in the interface between electronics and the human brain. Interfacing the most advanced human engineering endeavor with nature’s most refined creation promises to help elucidate aspects of the brain’s working mechanism and deliver new tools for diagnosis and treatment of a host of pathologies including epilepsy and Parkinson’s disease. Current solutions, however, are limited by the materials that are brought in contact with the tissue and transduce signals across the biotic/abiotic interface. The field of organic electronics has made available materials with a unique combination of attractive properties, including mechanical flexibility, mixed ionic/electronic conduction, enhanced biocompatibility, and capability for drug delivery. I will present examples of organic-based devices for recording and stimulation of brain activity, highlighting the connection between materials properties and device performance. I will show that organic electronic materials provide unparalleled opportunities to design devices that improve our understanding of brain physiology and pathology, and can be used to deliver new therapies.
On: March 23, 2016 From: 15h30 To: 16h30View talk