At the beginning of the 20th century, scientists discovered how to measure the size and spacing of atoms using a technique called diffraction, which led to a revolution in the understanding of chemistry, biology and solid-state physics. X-rays and electrons behave like waves, but with a wavelength which is much smaller than the spacing between the atoms of a solid. These waves scatter and interfere with one another, producing strong beams coming out of the object at particular angles. By measuring these angles, and knowing the wavelength of the waves, the separation of atoms could be calculated. It was using this method that Watson and Crick determined the structure of DNA in the 1950s. However, diffraction is only useful if the object is a regular lattice structure. In order to look at more complicated atomic structures, scientists have relied on electron or X-ray microscopes. In a standard microscope, a lens is used to produce a magnified image, but the method still relies on the waves that make up the radiation (light, electrons or X-rays) interfering with one another to build up the image. With light, this is experimentally easy, but with very-short wavelength radiation (a fraction of an atomic diameter), the tiniest error in the lens or the experimental apparatus makes the waves interfere incorrectly, ruining the image. For this reason, a typical electron or X-ray microscope image is about one hundred times more blurred than the theoretical limit defined by the wavelength.In this project, we aim to unify the strengths of the above apparently very different techniques to get the best-ever pictures of individual atoms in any structure (which is not necessarily crystalline). Our approach is to use a conventional (relatively bad) X-ray or electron lens to form a patch of moderately-focussed illumination (like burning a hole in a piece of paper with the sun's rays through a magnifying glass). In fact, we do not need a lens at all! Just a moveable aperture put in front of the object of interest will suffice. We then record the intensity of the diffraction pattern which emerges from the other side of the object on a good-quality high-resolution detector, for several positions of the illuminating beam. This data does not look anything like the object, but we have worked out a way of calculating a very good image of the object by a process called 'phase-retrieval'. To make an image of an object we have to know what's called the relative phase (the different arrival times) of the waves that get scattered from it. In diffraction, this information is lost, although some of it is preserved (badly) by a lens. Our data is a complex mixture of diffraction and image data, but the key innovation in this project is that we can use a computer to calculate the phase of the very high resolution data which could never be seen by the lens alone. Other workers in the United States have demonstrated very limited versions of this new approach, but we have a much more sophisticated computational method which eliminates essentially all earlier restrictions.The new method, which has received patent protection, could be implemented on existing electron or X-ray microscopes, greatly enhancing their imaging capability. It is even possible to contemplate a solid-state optical microscope, built into a single chip with no optical elements at all. All the weakness and difficulties and costs of lenses would be replaced by a combination of good quality detectors and computers. Our ultimate aim is to be able to image in 3D directly (using X-rays or electrons) any molecular structure, although this will require a great deal of research. The work put forward in this proposal will build the Basic Technology foundations of this new approach to the ultimate microscope.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

Aims The main aims of the proposed research are to: - Explore the geotechnical properties of materials susceptible to sinkhole formation. This includes determining which particular materials are likely to be weakened by long periods of dry weather followed by heavy rain, and which combinations of these conditions are likely to result in the greatest likelihood of sinkholes forming. Meeting this aim will improve understanding of the stability of these materials when supporting foundations over emerging cavities, and could facilitate the prediction of sinkholes in areas where land has already been developed, which could be used to prevent injury and potential loss of life. - Investigate the mechanisms involved in the development of different types of sinkhole, such as the softening and failure of historic chalk workings. An understanding of the physics involved in these failures could inform additions to building regulations and design codes for infrastructure and structures in areas susceptible to sinkholes. Method In order to meet the aims listed, the following research method is proposed: - A geotechnical desk study to identify suitable sites for sample extraction. This will be done using existing literature, as well as the BGS sinkhole database. - Samples of clay, chalk and other rocks will be taken from the selected locations at different times of the year, with technical support and drilling equipment to be provided by BGS. These samples will be used to determine a ground profile for the site. - The geotechnical properties of the samples, such as the relationship between water content and strength will be tested. This will be carried out in lab facilities provided by BGS. - Based on the geotechnical properties and ground profile of the site, scale models of typical sinkhole prone formations will be produced for testing in a centrifuge, to generate typical in-situ stresses. This will require the use of further samples or of synthetic soil material. The centrifuge is an existing facility at the University of Sheffield. - A technique for simulating aging effects of different antecedent conditions on the models will be developed. This may require new equipment such as drying and humidifying devices. The technique will be verified by comparison of artificially aged rocks with naturally weathered rocks. - Rock and soil models with different moisture contents, and ageing conditions will be produced. - These models will be tested in the centrifuge and their failure mechanisms studied and classified using image analysis techniques, such as particle image velocimetry, and calculated back analysis. - The relationship between water content, strength and ageing conditions will be analysed and the critical combination resulting in the most sinkholes determined.

As we increase the air tightness of our buildings in line with more stringent building regulations it is vital to specify adequate fresh air ingress to all occupied spaces to ensure the health and well-being of occupants. In order to optimise buildings for energy and health it is important that we have a comprehensive understanding of the dynamics of indoor air flow, which is complicated by the impact of human behaviour. Current knowledge of how humans interact with their environment and implications for the airflow within buildings is virtually non-existent. This proposal aims to develop facilities for investigating the detailed fluctuations of air movement due to occupants opening and moving through doorways. This will have a significant impact on the understanding of contaminant transport and fresh air ingress into buildings; it will also have implications for ventilation specification and simulation as well as building energy prediction.

The UKs Sixth Carbon Budget set into law the world's most ambitious climate change target, cutting CO2 emissions by 78% of their 1990 levels by 2035, and bringing the UK towards a net zero carbon emission target by 2050. This ambitious target will be realised using a combination of renewable energy sources with energy from nuclear fusion, which offers the ultimate clean power solution, playing an important role in the transition to the required low carbon future. The Spherical Tokamak for Energy Production (STEP) is a UKAEA programme that will deliver net electricity generation from fusion within a very ambitious time frame, with a targeted completion of 2040. The design of STEP will require components to operate at higher doses and higher temperature than ever experienced in service and of course with long component lifetimes to ensure economic energy production. The current reduced activation ferritic martensitic (RAFM) steels for breeder blanket components of fusion reactors are not good enough to survive these conditions. For example, current RAFM steels, such as F82H and Eurofer97, possess a limited application temperature range of ~330-550oC. This project will design new advanced RAFM steel compositions that will offer superior creep resistance as well as exhibiting greatly improved impact properties, allowing these steels to operate at higher temperatures (>550oC) and be better able to resist radiation hardening/embrittlement and radiation enhanced creep. This will be achieved using a programme of innovative alloy design and novel thermomechanical processing (TMP).