It is widely acknowledged that the oceans and polar sea-ice play critical roles in global climate change. As such, sea surface temperature and polar sea-ice reconstruction should be of paramount importance in establishing climatic evolution of the geological past. Although direct records of sea-ice are considered to be reasonably accurate over the last 200 years (with satellite imaging for the past 30 years), it is only through the use of 'proxy' measures (chemical, physical or biological indicators of sea-ice) that a more extended record is achievable. The main aim of the current project is to measure the concentrations of Highly Branched Isoprenoid lipids along a sediment core retrieved during the IODP Wilkes land Expedition 323. Preliminary studies have shown that these chemicals are stable in Antarctic sediments and, while the presence of a specific isomer (a di-unsaturated HBI isomer) in these sediments can be directly attributable to previous sea ice cover, the presence of a tri-unsaturated HBI in these sediments was found to reflect the absence of sea ice. Similarly, past surface oceanic conditions (temperature, stratification), sea ice cycles, and siliceous productivity variations can be investigated via diatom assemblage determinations and investigation of elemental geochemistry in sediments. In this collaborative project, we will carry out a multi-proxy analysis of a marine core retrieved in the Adelie land area at an unprecedented sub-seasonal resolution throughout the entire Holocene. The diatom census counts and elemental analyses will be completed by the project partners. Given the diversity of the data available, together with the high temporal resolution, this project represents a unique 'case study' opportunity to establish the relationships between different proxies and to enable future studies in palaeoclimate reconstruction to be more fully understood. The data from this project will also be used directly by modellers of climate change.This project fits well with other aspects of the Council's programme and clearly has a 100% relevance to both the 'Polar South' classification and the 'Global Change' ENRI. The project represents excellent value for money, especially considering the commitment of the project partners. All of the necessary chemical and analytical requirements are held in-house within the Petroleum and Environmental Geochemistry Group at the University of Plymouth. The project will also benefit from additional staff expertise available both locally and internationally.

Controlled motion is required for essentially all human activities. Key advances in civilisation have been associated with technological breakthroughs that have facilitated movement. At the microscopic scale, precise control of motion at the molecular level is used to regulate important biological functions. Currently, there is enormous interest in the synthesis and application of man-made devices whose motion can be controlled by external stimulii. Three types of external inputs - that is chemical, electrochemical and photochemical - have been used to induce well-defined rotational or translation movements within these so-called molecular machines. Of all the nanoscale devices studied to date, the simplest is perhaps the molecular switch. Molecular switches hold enormous promise in the development of new materials for information storage and retrieval at the molecular level. Existing classes of molecular switches suffer from several drawbacks (e.g. complex synthesis, reliability), so work to discover and develop new types of molecular switch is much needed. This research proposal is focused on making and studying new types of nanoscale switches based upon exploiting the motion associated with pyramidal nitrogen inversion (also called atomic or umbrella inversion). In pyramidal inversion, the linear movement comes from the apical substituent on the nitrogen moving laterally from one side of the molecule to the other (a movement not dissimilar to that witnessed when an umbrella is blown inside out by strong winds). We suggest that the speed of motion associated with this movement, and the relative amounts of the two forms of the molecule (called the invertomers) can be reversibly controlled by external stimuli (e.g. light, added chemicals or electrons). Initial experiments conducted in our laboratories using a system that responds to the simultaneous addition of electrons and protons (a redox process) provides strong evidence in support of this hypothesis. Here, we plan to further develop these ideas by building and studying a broad range of molecular switches that are designed to exploit our ability to exert control over this type of motion. Our focus will be on systems based upon a well-known heterocyclic ring system called an aziridine. In the context of developing new molecular devices capable of controlled motion, aziridine based systems offer several unique features. In the absence of strong acid or nucleophiles, N-alkyl aziridines are rather stable molecules. Furthermore, they are simple structures to assemble, with the possibility of placing several different groups close to the inversion centre, each with very predictable and precise orientations in three dimensional space. Quantitative data relating to their speed of motion can easily be obtained using NMR spectroscopy. The rate of motion can be fine tuned by altering the substituent pattern around the heterocyclic ring. Moreover, valuable data concerning the inversion process can be obtained from calculations performed using computer based methods which can greatly aid the design process. The principles learnt here concerning controlled motion associated with pyramidal inversion in aziridines could readily be extrapolated to other classes of N-heterocycles, and to heterocycles containing other non-carbon atoms (e.g. phosphorus) possessing vastly different switching rates. Hence, general rules concerning building molecular devices based on exploiting atomic inversion are expected to emerge from this programme.

Controlled motion is required for essentially all human activities. Key advances in civilisation have been associated with technological breakthroughs that have facilitated movement. At the microscopic scale, precise control of motion at the molecular level is used to regulate important biological functions. Currently, there is enormous interest in the synthesis and application of man-made devices whose motion can be controlled by external stimulii. Three types of external inputs - that is chemical, electrochemical and photochemical - have been used to induce well-defined rotational or translation movements within these so-called molecular machines. Of all the nanoscale devices studied to date, the simplest is perhaps the molecular switch. Molecular switches hold enormous promise in the development of new materials for information storage and retrieval at the molecular level. Existing classes of molecular switches suffer from several drawbacks (e.g. complex synthesis, reliability), so work to discover and develop new types of molecular switch is much needed. This research proposal is focused on making and studying new types of nanoscale switches based upon exploiting the motion associated with pyramidal nitrogen inversion (also called atomic or umbrella inversion). In pyramidal inversion, the linear movement comes from the apical substituent on the nitrogen moving laterally from one side of the molecule to the other (a movement not dissimilar to that witnessed when an umbrella is blown inside out by strong winds). We suggest that the speed of motion associated with this movement, and the relative amounts of the two forms of the molecule (called the invertomers) can be reversibly controlled by external stimuli (e.g. light, added chemicals or electrons). Initial experiments conducted in our laboratories using a system that responds to the simultaneous addition of electrons and protons (a redox process) provides strong evidence in support of this hypothesis. Here, we plan to further develop these ideas by building and studying a broad range of molecular switches that are designed to exploit our ability to exert control over this type of motion. Our focus will be on systems based upon a well-known heterocyclic ring system called an aziridine. In the context of developing new molecular devices capable of controlled motion, aziridine based systems offer several unique features. In the absence of strong acid or nucleophiles, N-alkyl aziridines are rather stable molecules. Furthermore, they are simple structures to assemble, with the possibility of placing several different groups close to the inversion centre, each with very predictable and precise orientations in three dimensional space. Quantitative data relating to their speed of motion can easily be obtained using NMR spectroscopy. The rate of motion can be fine tuned by altering the substituent pattern around the heterocyclic ring. Moreover, valuable data concerning the inversion process can be obtained from calculations performed using computer based methods which can greatly aid the design process. The principles learnt here concerning controlled motion associated with pyramidal inversion in aziridines could readily be extrapolated to other classes of N-heterocycles, and to heterocycles containing other non-carbon atoms (e.g. phosphorus) possessing vastly different switching rates. Hence, general rules concerning building molecular devices based on exploiting atomic inversion are expected to emerge from this programme.

Atmospheric composition and climate are closely linked because compounds such as carbon dioxide and methane are greenhouse gases: increases in their concentration are expected to warm the atmosphere. Such increases have occurred in the last two centuries, and are expected to accelerate in the next few decades. However, exactly how these concentrations and climate will evolve together depends on processes that link them within the so-called Earth System. Our understanding of these processes is expressed in models that represent and connect parts of the system such as the growth of vegetation, ocean circulation, atmospheric circulation and chemistry, etc. However, the best way we have of validating whether these models are correctly representing the Earth is by looking at the past. Various palaeoclimate records provide us with a view of how climate has behaved in the past. The ice core record is particularly valuable because it shows how both climate and atmospheric composition have evolved over the last 800,000 years. During this time, the Earth has passed into and out of glacial states many times, and it turns out that the principal greenhouse gases and climate have varied together during this period. Carbon dioxide and methane have high concentrations during warm interglacials and low concentrations in cold glacials. They thus offer numerous examples of how climate reacts to changes in atmospheric composition, and strong clues about how the sources and sinks of carbon dioxide and methane react to climate change. Our current understanding is that methane increases when climate warms because of a combination of expanded wetland sources and diminished atmospheric sinks. However, we lack many details about these sources and sinks, and have no clear evidence to differentiate their respective roles. For carbon dioxide, the changes are believed to stem mainly from processes in the Southern Ocean, but within this view there are a number of competing hypotheses. This proposal will combine the strongest elements of the relevant observational and modelling communities in the UK and France. Firstly, we will examine both the ice core and other datasets to provide as many constraints as possible on the causes of change in concentration of carbon dioxide and methane. This will involve particularly new measurements of isotopes of carbon that are diagnostic of sources, and new measurements of marine sediments in the Southern Ocean that can constrain mechanisms for changes in the carbon cycle. Particular aspects of the emission and processing of methane and carbon dioxide will be considered in order to make necessary improvements in models. We will then use a variety of models of different levels of complexity to explore the major changes seen in the ice record: between cold glacials and warm interglacials, between different interglacials, and at other particular times in the last 800,000 years that may allow us to differentiate the operation of certain mechanisms. Detailed models, including the new QUEST Earth System Model, will be used to assess the production and loss of methane at particular times in the record. Models of lower complexity will be run over longer time periods to determine the expected signal in different palaeoclimate archives of various mechanisms for changes in carbon dioxide, with a view to narrowing the uncertainties on the importance of each mechanism. Models will also be used to test whether we can understand the different climates seen in past interglacials knowing the energy input from the Sun and the concentrations of greenhouse gases seen in ice cores. The end result of this project will be an improved ability to simulate the past, a better understanding of the processes that control atmospheric composition, climate and the carbon cycle and, as an end result, an improved representation of all relevant processes in models used to predict the future evolution of the Earth System.

We aim to grow specific-sized metal and semiconductor nanoparticles inside rigid molecular cages called cucurbiturils, and subsequently assemble them into functional nano-chains. Combining these filled cages with well-defined connector molecules allows us to precisely define particle geometries, particle separations and particle interfacing. This in turn enables the robust construction of plasmonic optical antennae at visible wavelengths, room-temperature single-electron-tunnelling transistors and combined photovoltaics. Such functional properties open up novel alternative methods for directed assembly using irradiation with precisely-tuned lasers, nano-electrochemistry or ac-electric fields. This approach will constitute the basis of a new nanotechnology platform for organic-inorganic ordered nano-composites.