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E440: From bugs to brains: magnetism and microscopy of iron (hydr)oxide nanoparticles in the natural environment (Lead Supervisor: Richard Harrison, Earth Sciences)

Supervisors: Richard Harrison (Earth Sciences), Emilie Ringe (Earth Sciences & Materials Science and Metallurgy) and Sasha Turchyn (Earth Sciences)

Importance of the area of research:

Alzheimer's disease is the leading cause of death in England and Wales. A recent study has suggested a link between iron oxide nanoparticles derived from vehicular pollution in the human brain and the development of neurodegenerative diseases, such as Alzheimer's (ref 1). Understanding the origin and distribution of such particles in the environment is, therefore, of fundamental importance. More broadly, Fe-based microbial metabolism plays a profound role in the biogeochemical cycling of Fe in diverse sedimentary environments. Variations in magnetic susceptibility and hysteresis parameters provide a rapid and sensitive means to trace variations in the biogeochemistry of sediment cores. New magnetic methods are enabling such processes to be quantified in unprecedented detail (ref 2), yet the mechanisms that link macroscopic magnetic properties to the underlying iron oxide morphology and chemistry are poorly understood. Although some insights through careful laboratory experiments have been made, our knowledge of the particles that occur in real environments, and their fundamental magnetic properties, is very limited.

Project summary:

This project will develop state-of-the-art, high-resolution characterization tools to evaluate the morphology, structure, chemistry, redox state and magnetic properties of iron oxide nanoparticles, with broad applications to environmental science, human health, climate science and beyond. The project will also continue our development of new and innovative magnetic methods for the detection and characterization of variations in iron (hydr)oxide nanoparticles in a range of samples, from sediments and soils to air filter samples collected for monitoring particulate pollution in urban environments. The ultimate aim is to link the macroscopic variations in magnetic properties for a given suite of related samples to the underlying properties of the nanoparticles.

What the student will do:

The student will use cutting edge methods to explore the distribution of redox and crystallographic states of iron (hydr)oxide in natural and synthetic materials. Working jointly with ES and MSM will enable full access to exciting samples, expertise and state-of-the-art instrumentation. The student will make extensive use of electron-beam techniques, for both structural, electronic and magnetic characterization of the nanoparticles. Structural analyses include scanning electron microscopy, scanning transmission electron microscopy (STEM), 3D reconstructions using STEM tomography, as well X-ray and electron diffraction. The student will gain knowledge about the electronic structure, and thereby the redox state, using electron-energy loss spectroscopy (EELS), and this will be combined with structural features via the development of computer models and data analysis algorithms. The student will also use electron holography (ref 3) to image the magnetic state of particles directly at the nanoscale, enabling a link to be forged between the nano and macroscale properties observed using modern magnetic methods, such as first-order reversal curve (FORC) diagrams.

Please contact the lead supervisor directly for further information relating to what the successful applicant will be expected to do, training to be provided, and any specific educational background requirements.

References:

Maher, B.A., Ahmed, I.A.M., Karloukovski, V., Maclaren, D.A., Foulds, P.G., 2016. Magnetite pollution nanoparticles in the human brain. PNAS 113, 10797-10801.

Lascu, I., Harrison, R.J., Li, Y., Muraszko, J.R., Channell, J.E.T., Piotrowski, A.M., Hodell, D.A., 2015. Magnetic unmixing of first-order reversal curve diagrams using principal component analysis. Geochemistry, Geophys. Geosystems 16, 2900-2915.

Reichel, V., Kovács, A., Kumari, M., Bereczk-Tompa, É., Schneck, E., Diehle, P., Pósfai, M., Hirt, A.M., Duchamp, M., Dunin-Borkowski, R.E., Faivre, D., 2017. Single crystalline superstructured stable single domain magnetite nanoparticles. Nat. Publ. Gr. 1–8.

Follow this link to find out about applying for this project.

Other projects available from the Lead Supervisor can be viewed here.

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