Arrive for 19:00
Wednesday Feb 8, 2017
Entry is free. Members and non-members are welcome.
Radiation detectors are needed at nuclear facilities in the UK to allow radiological characterization of legacy plant, in preparation for decommissioning. Often these plant have restricted physical access making surveys difficult. Moreover, intense radiation fields saturate or destroy conventional semiconductor-based radiation detectors. Conventional detectors are therefore restricted to low dose rate environments. Electronic-grade, single crystal diamond offers an alternative detector material which can provide dose rate information from within intensely radioactive facilities. This technology has the potential to characterise facilities previously too radioactive to measure with conventional detectors. Calibration work will be presented so that diamond detectors can be used to make dose rate measurements.
By 2050 there'll be over a billion more people on earth than today, mostly in LEDCs - all these people will need somewhere to live. If we're all to have homes which are sufficiently affordable, sustainable and attractive, we'll need new types of construction materials. Geopolymer-stabilized soil materials (GSSM) have the potential to be a superior option than current materials.
The useful properties of GSSM arise from the stabilizing presence of an amorphous geopolymer phase. This is formed by a reaction between the clay minerals in soil and a strong alkaline solution.
Development of GSSM is limited by a lack of understanding of how this reaction varies between different soils. My PhD research seeks to overcome this by investigating the geopolymer formation reaction in three different pure clay minerals. The aim is to produce a chemical 'recipe book' for how to use this technology on any given soil.
The decommissioning of Magnox nuclear reactors will lead to a large quantity of graphite waste requiring disposal. A knowledge of the concentration and distribution of radionuclides is important in the safe management of this waste. Analysis using secondary ion mass spectrometry as well as thermal oxidation with liquid scintillation counting that has shown that a surface deposit found on Magnox graphite, specifically Oldbury, is relatively enriched in 14C. This 14C in the deposit is indicative of the labile fraction previously observed in leaching studies with two further fractions of 14C observed, both correlating with previous leaching studies. The concentration of 14C in the deposit appears to be greater in samples originating lower in the channel than higher up, with possible explanations being the availability of nitrogen precursor species or deposition being more favourable at the lower temperatures found lower in the channel.
Activated carbon is a surprisingly ancient material, which happens to have a lot in common with Leerdammer cheese. Carbons may not be bright yellow, nor are they really edible, they are however full of holes. In fact it is their thousands of nano-scale sized pores (a nanometre is one millionth of a millimetre) which makes them potentially world-saving! Activated carbons are able to remove toxins from our water supply by a process known as adsorption. The molecules simply stick to the surface of the carbon, where we can destroy them with heat.
One of the key parameters for carbons to remove water toxins effectively is their porosity; the shape and size of their nano-scale holes. This research is aims to trap trickier to remove toxins by controlling the porosity of the carbon. We start with a natural polymer called lignin, which is found in all plants, and is a major by-product of the paper industry. We determined the structure of the polymer and how it varies between different plants. Using this information we have managed to control the type of carbon we make, simply by changing the plant our lignin comes from. Controlling the carbon structure like this is the first step to targeting water toxins. Our future research focuses on further controlling the pore sizes, and testing these materials against the difficult to remove pesticide metaldhyde.
Alloys exhibiting the shape memory effect (SME) have found applications as actuators in a number of materials required in the automotive, aerospace, robotic, biomedical and structural sectors.
Shape memory alloy (SMA) production by sputter deposition techniques has experienced a surge in recent years. Research can be quickly and efficiently conducted on heavily tailored samples which can often exhibit superior SME characteristics over their equivalent bulk counterparts.
Additionally, SMA thin films have found their own use as microactuators for microelectromechanical (MEMS) applications. In particular, the nickel-titanium (NiTi) binary system will be discussed, the material commanding the greatest breadth of research due to its inherently strong SME tendencies, versatility and extensively developed theoretical background.
Polymers are one of the fastest growing areas in biomaterials, and are used in a wide range of medical applications. One the limitations of many medical polymers is low visibility in x-ray images. X-ray imaging can be used to assess implant positioning and function after an operation and it is also possible to use x-ray fluoroscopy to aid implant positioning during surgery. This presentation explores the current approaches used to enhance the radiopacity in polymers, focusing on two implantable polymeric materials; polymethyl methacrylate (PMMA), and ultra-high molecular weight polyethylene (UHMWPE). These polymers are used clinically for long term implant applications, such as hip and knee replacements, where they are in direct contact with biological tissues and subjected to challenging mechanical and chemical conditions.