ransitional.dtd"> BSS - Postgraduate Admissions spectus for details of the application and admissions process for postgraduate study.

Projects marked with * are also suitable for an MPhil. Projects marked with ** are only suitable for an MPhil.

Dr S Bohndiek

Our research goal is to understand the role of redox processes in the development and progression of disease, with a particular focus on cancer. At present, the technical approaches to measuring the actions of free radicals and antioxidants in intact biological systems are insensitive, difficult to interpret and prone to artifact. As a result, little is known about the role of oxidative stress, an imbalance of free radicals and antioxidants, in cancer initiation and the evolution of chemotherapy drug resistance. We aim to develop molecular imaging techniques sensitive to small changes in redox processes, over short time scales, with specificity to particular redox systems. We will employ existing imaging methods and create new approaches, through both instrumentation and contrast agent development, in order to achieve this goal. Our approach features a specific emphasis on clinical translation, using methods that can be applied in cells in culture, in small animals and ultimately in humans.

This research programme is inherently interdisciplinary and many projects will be carried out in collaborations within BSS, with others in Cambridge and with other institutions. We strongly encourage applications from those with a strong interest in physics applied to medicine, regardless of their specific scientific backgrounds. Our efforts can broadly be summarized in three key areas, although there will always be significant overlap in any given project. Please contact me directly for more details on the research described below and to discuss related directions that you may wish to pursue.

Development of ultrasensitive molecular imaging tools

Molecular imaging provides a visual representation, characterization and quantification of biological processes in intact living organisms, from microscopy studies of live cells up to macroscopic imaging of humans. Crucial to the research programme of our laboratory is the development and application of advanced biomedical tools that exploit new contrast mechanisms for imaging. Tissue optical imaging has progressed dramatically in the past decade; examples with translational potential include Raman spectroscopy and photoacoustic tomography. A myriad of contrast mechanisms are accessible by exciting tissues in the wavelength range from RF to IR and we are only just beginning to realise the full potential of this approach for molecular imaging in living subjects. Those with a strong interest in optics, electronics, imaging, instrumentation development and/or biomedical physics would be ideally suited to work in this area.

Design of “smart” contrast agents to probe specific redox processes

While molecular imaging approaches ideally exploit contrast mechanisms intrinsic to the cell using “label free” methods, our imaging systems are often not sufficiently sensitive to probe a given biological process of interest. Instead, a contrast agent must be developed that can be activated by the given process. Many constraints must be fulfilled in order to develop an effective “smart” contrast agent. For example, ideal redox sensors should be non-disruptive, non-toxic, cell permeable, and respond dynamically and specifically to a particular redox process. We are seeking researchers with a background in chemistry, chemical engineering, biochemistry or related disciplines to work in this area.

Application of new imaging methods to biological questions in relevant disease models *

Free radicals are generated as a normal by-product of respiration. Oxidative stress, and eventually cell death, occurs when the concentration of free radicals exceeds the capacity of the intracellular antioxidant systems; this plays a key role in the progression of a range of pathologies. In particular, free radicals are involved in all aspects of malignant transformation and progression, from initiating DNA damage to facilitating apoptosis triggered by chemotherapy. The ability of cancer cells to survive extreme levels of oxidative stress has been strongly associated with aggressiveness and drug resistance, but to what extent this is causation or simply correlation in vivo is unknown. Our hypothesis is that an elevated antioxidant capacity enables some cancer cells to resist chemotherapy and that noninvasive imaging of intracellular redox state will allow us to detect the emergence of resistance earlier. If this hypothesis is true, translation of our imaging techniques into clinical application could improve our ability to detect relapse and aid the selection of combination therapies, leading to better outcomes for cancer patients.

To test our hypothesis, we work with both cell culture and animal models of cancer drug resistance and apply our new imaging approaches to explore how different redox systems are modulated during the evolution of drug resistance in vivo. Furthermore, as many fundamental biological processes altered in activated tumour stroma are also affected in neurodegenerative disease, similar approaches could in future be applied to the study of Alzheimer's and Parkinson's diseases. Researchers with experience or interests in molecular imaging of living subjects, image reconstruction and analysis, redox biology and biochemistry, and related disciplines are encouraged to work in this area.

Dr K Chalut

There is an important but unfilled niche at the intersection of embryonic stem (ES) cell biology and physics: forces and motion, as well as intrinsic structural properties of ES cells, modulate the placement of cells within the embryo; this positioning augurs their eventual fate. Although much is known about the biochemical signatures of events in the developing embryo – how the gene expression of specific developmental markers changes at particular times in the life cycle of an embryo – much remains to be elucidated about the role of physics. Little is known about individual physical characteristics, or phenotypes, of these cells, less how and why they matter, and how they coalesce in embryonal dynamics. The proposed research is driven to fill this niche. We strive to understand how physical parameters drive ES cell state, or the present condition of ES cells, regarding their fate decisions. Do nuclear mechanics play a role? What about the structure and organisation about the genome? The genome is after all a physical formation with dynamics. We are developing biotechnology to observe the physical world of embryos and embryonic stem cells, with the aim of understanding how physics drives biological development.


We will strive to use existing techniques in the Physics of Medicine facility such as optical stretching, atomic force microscopy, compliant gel substrates and digital holographic microscopy for studying physical phenotypes of ES cells. We are pushing digital holographic microscopy forward to enable meausurement of 3-D refractive index maps of single cells to give unprecedented views of subcellular structure. We will also be developing new techniques such as microfluidic cell rheology, which is a microfluidic-based technique for high-throughput measurements of mechanical phenotypes of single cells. Another technique we will develop in our laboratory is nanoparticle tracking techniques to measure nuclear mechanics within embryos. In this area of research, we are seeking researchers interested in optics, bioimaging, and nanobiotechnology.

Physical phenotyping

We will use our developed biotechnology to establish physical phenotypes of stem cell pluripotency and differentiation. The physical phenotypes we will primarily explore are nuclear mechanics and structure, and how they correlate with the state of embryonic stem cells. We are particularly interested in the role the remodelling of chromatin &endash; the machinery in the nucleus of which chromosomes are built &endash; plays in ES cell function. Chromatin is highly dynamic: in order to control accessibility to the genome, it condenses or decondenses, and moves throughout the nucleus as a cell fulfils its function. The physical phenotypes we will study focus on more big-picture views of cell behaviour to generate a broader understanding of changes in cell function, and will emphasize marker-free and non-perturbative techniques of biological observation.

Biophysics of development

In this aspect of our research, we will be testing the hypothesis that the decisions of embryonic development are driven by biophysics, such as cell/nuclear mechanics and chromatin structure. A particularly enticing aspect of this is to consider that ES cells are controlling their development – i.e. what somatic cells they are to become – by physically regulating access to the genome. We have evidence that this is the case, and we will continue by using particle tracking rheology and refractive index imaging to assess how the physical phenotypes of ES cells change as they sort in the embryo, and at what point in the sorting process these physical phenotypes change. In this area of research, we welcome those interested in bioimaging and biophysics, and also molecular biologists or embryologists interested in the role of biophysics in development.

Dr P Cicuta

Bacteria and micro-organism growth in microfabricated controlled environments (up to two projects; 3.5 years)

In the last few years we have developed microfluidic environments for the controlled growth of unicellular organisms. This enables very accurate and extensive measurements of bacteria physiology, which in turns justifies quantitative (i.e. physics!) modelling of various processes taking place inside the organisms.

Project #1: bacteria such as E.Coli and Salmonella are pathogens, but are also platforms for biotechnology. For both reasons, it is very important to understand their cellular behaviours as much as possible. Although they are amongst the most studied organisms in biology, there is a still a lot that is unclear; some of these aspects seem amenable to “physics”, for example the role of confinement and generally DNA conformation on the regulation of gene expression (protein formation). This is in collaboration with various colleagues in Cambridge (G.Fraser; C.Bryant; D.Sommers) and Paris (M.Cosentino Lagomarsino; B.Sclavi).

Project #2: in collaboration with Prof.Alison Smith in the Plant Sciences department, we have started to work on understanding how certain unicellular algae grow optimally in the presence of a bacterial partner. It seems that each species is producing an excess (relative to its needs) of molecules, which are needed by the other, and are exchanged with the other species.

Understanding these simple "ecological" networks is a step in optimising the growth conditions of the algae, which are a promising source of carbon neutral bio-energy (and bio-fuel) for the near future. The project involves looking at this algae/bacterium system at the "single-cell" level. That is monitoring the growth and fate of each cell, instead of the more conventional population average. Obviously a more challenging experiment, but essential to determine the heterogeneity in a population, and the presence of possible outliers or mutants that might be selected for useful traits.

The student(s) would be trained in the fabrication of microfluidic chambers, which are essential for growing and imaging cells at single-cell. Using custom setups for automated imaging (a speciality of our group) growth experiments will be carried out in different conditions. An interest in the behavior of biological systems is required, although no previous knowledge is necessary. It is also possible to "reach out" into more theoretical investigations (mathematical modeling).

Malaria infection with advanced optical trapping techniques (3.5 years)

Malaria is one of the deadliest diseases in the world, and is also a key factor in the underdevelopment of entire regions. There are no effective vaccines, and drug resistant strains are emerging. It is a complex disease, with the parasite residing alternatively in the mosquito and in the human body.

In the body, there is a stage where the unicellular parasite resides in red blood cells, and grows in number by replicating within a cell and then escaping to infect other red blood cells. While this is a promising stage for intervening with drugs or vaccines, it has been challenging to observe cell invasions in the lab. This is because these are rare and fast processes: the egress of parasites takes place after 24 hours of maturation, and from that moment, the invasion of a new cell takes place over just a few minutes.

We have recently developed an automated imaging platform that finds infected cells and records the egress/invasion sequence without user intervention. This greatly facilitates acquiring invasion optical microscopy data.

The PhD project will build on the existing platform, working to integrate automated functional imaging; higher resolution imaging; optical trap micromanipulation.

Microscopic Swimmers and Pumps (3.5 years)

Life at the cellular level takes place at low Reynolds number (Re), i.e. biological flows are dominated by viscous forces. In order to generate flows or to propel themselves, cells and bacteria have adapted techniques which are very different from the way that pumping and swimming occur at macroscopic scales (everyday flows are high Re). Optical tweezers allow us to exert and measure forces of the order of pico-Newtons, by holding and moving micrometer sized beads. We have recently shown how the possibility of actively moving colloidal particles can be used fruitfully to model the action of cilia and flagella, opening up a new area of research in exploring how the coordinated motion of these elements arises out of hydrodynamic interaction.

Professor AM Donald

Self Assembly Under Flow in Aggregating Proteins

Proteins show a tendency to aggregate into fibrillar and suprafibrillar structures when factors encourage their unfolding or misfolding. These aggregates are known to underlie the development of diseases of old age such as Alzheimer~s and Parkinson~s Disease. We have recently shown that flow, including stirring, can have a substantial effect on the fibrillar aggregates that form, changing their length and how they assemble at larger length scales. In order to control the flow history, a microfluidics device has been built, and preliminary results have shown some very striking changes for insulin aggregation as the flow rate is altered. There are many unanswered questions which we want to explore: what do the constituent fibrils look like at different times? Do surfaces nucleate aggregation? How does constant versus pulsed flow affect the structures which form? How do electrostatics affect the aggregates? Do all proteins behave similarly? A combination of microfluidics and different kinds of microscopy and spectroscopy will be used in this project.

Physical Processes involved in Cell Adhesion and Mobility

In order for cells to adhere, proliferate and move they need to be able to interact with the substrate through the formation of specific contacts (e.g focal adhesions). By using modified surfaces, such as those with chemical or physical patterning, together with novel live cell dyes, it is becoming possible to unravel the nature of the interactions and their impact on processes such as motility and division. We will work with a variety of cell lines (and in close collaboration with biomedical scientists), using light (confocal/fluorescence) and electron microscopy to explore these questions at a physical level to help build up a fuller picture of the processes involved.

Dr E Eiser

Colloidal crystals

The fascination of researchers with colloids started with Perrin and Einstein in the early 20th century, when the existence of atoms was confirmed. It was Perrin and Einstein who realized that one-micrometer large particles (colloids) that are observable by a microscope in time can be used as model system to describe equilibrium properties of atomic or molecular systems. Since then researchers, in particular theoreticians and simulators computed the phase diagrams of colloidal systems for different interaction potentials that would reflect atomic interaction potentials. Very soon it was discovered that for a binary system where the ratio between large to small colloids is about 20 or larger, a distinct solid-to-solid transition must exist. Although we know from condensed metals, that structural polymorphism exist, experimentalists were until now not able to observe such transitions in binary colloidal systems. The main reason is that while atoms of one type are perfectly monodisperse in size, it turned out to be very difficult to make sufficiently monodisperse colloids.

In this project the student will explore colloidal crystallization with a new type of colloid produced here in Cambridge. To study the crystalline structure of the colloids and analyze them the student will have to build a static and dynamic light scattering setup. This demands very good experimental, optics and electronics/computational skills.

DNA-based nanomachines: building molecular sensors

The fact that DNA is made of two specific polymers that are held together by hydrogen bonds alone makes it a very versatile system that can be used to build new nano-machines. Hence by choosing the appropriate sequence of bases in the single-stranded DNA chains one can build arbitrarily many structures ranging from nanometer seized tetraheder to "smilies" and other exotic structures. However, a more practical application of short DNA strands is their potential for biosensors. One example is the detection of single base-pair mismatches. In this case one makes use of collective interactions induced by the presence of gold-nanoclusters. pH-sensitive DNA-switches provide a second example. Here specific folding properties of DNA (forming a so-called I-motive) are used. Such switches can be introduced into confined areas such as cells or nuclei detecting the pH locally.

In this project we use Holliday-junctions (4-way junctions made of four different single strands) to develop logical switches such as AND or NOR switches that could be used both as building blocks to make photonic crystals and/or molecular motors. Although this project is mainly experimental, extensions to theory and simulation studies are possible.

Aggregation and phase behaviour of proteins

While proteins are the motors that make our body function they can also cause severe diseases ranging from cataract formation in the eye lens to Parkinsons or Altzheimers disease. Their generic characteristic is the aggregation of a specific protein. In Altzheimers disease it is the tau-protein that leads to filamentous amyloid-formation while the turbidity (cataract) in eye lenses is due to the aggregation of crystallin-proteins. Although each disease is related to the aggregation of a specific protein, they all suffer from the fact that these aggregates seem to form irreversibly, which makes it hard to treat.

Recently we have discovered that the aggregation of ovalbumin in egg white observed when boiling an egg can be not necessarily reversed into a solution of well folded functional protein but transformed into a different type of gel with optical and mechanical behaviour very different to that of a hard boiled egg or the raw viscoelastic egg white. Further experiments also indicate that the change in aggregation can be explained on the grounds of colloidal physics. Colloids are small entities with sizes ranging between a few nanometres up to microns. Consequently, their behaviour is determined by thermal motion and therefore need to be described with statistical mechanics. Examples of colloids are polymers, viruses, hard spheres, or red blood cells amongst many others. Thus, the biological or chemical nature is not primarily important for the understanding of the phase diagram of colloidal systems. It is rather the interactions between colloids (typically due to Coulomb, van der Waals, steric and depletion forces) that determine their phase behaviour. These interactions can be fine tuned by varying parameters like the ionic strength (in charged systems), temperature or the addition of other molecules. A great example of such fine tuning is milk. Adding bacteria that change the pH of the solution makes the protein (casein) micelles in milk aggregate into a soft gel. While rennet, an enzyme that cuts of the stabilizing part of casein micelles, transforms milk into a tougher gel that we know as cheese.

In this project we want to understand the aggregation observed in globular proteins such as ovalbumin or serum bovine albumin that form at high pH, by building a model colloidal system that can elucidate the general aggregation paths and the relevant interactions involved. We use fluorescently labelled colloids to track aggregation in real time and space using microscopic techniques. Furthermore we want to investigate possible routes to reversibility.

Dr Yan Yan Shery Huang

Direct-write biomaterials

Room temperature deposition and patterning of circuitry may circumnavigate the need for conventional energy- and time-intensive fabrication of functional materials. It is also a requirement if components need to interface with biological tissues. By subjecting a polymer solution to a defined electric field, fine liquid jet is created which can then be used to perform direct deposition of functional materials. Near-field electrospinning (NFES) is based on this principle which creates sub-micron pattern resolution. The unique advantage of NFES is that the mild processing conditions permit direct writing of patterns on soft bio-compatible substrates, which are mostly gel-like in nature. Recently, we have demonstrated the potential applications of this technique in stretchable electronics (http://nanotechweb.org/cws/article/lab/48940). We are currently developing this process to enable the fabrication of a range of biomaterials.

Tailoring soft composites for tissue regeneration*

Mechanical stiffness of the interfacing substrate plays a critical role in the process of cell differentiation/ growth and tissue regeneration. An emerging focus is to develop material interfaces which have mechanical compliance akin to the soft biological surroundings where the bioelectronics are embedded. Combining long thin -Fˇflexible˘ conductors (carbon nanotubes) inside a soft polymer-A matrix forms a composite system ideal for stretchable, soft electrodes. These compliant electrodes will see a wide range of applications where electrical stimuli are required to deliver to the cellular system, a good example being the brain electrode. A new process of centrifuge film forming technique has been developed to tailor the electrical conductivity and mechanical compliance of the composite. The project is hoped to bring further understanding in how the change in different physical environments (such as stiffness, electrical stimuli, surface roughness and anisotropy) will affect the differentiation/ growth of different cell lines. The results also hold the key to optimise the material microstructure for bioelectronic applications.

Probing electrogenic activity of photosynthetic bacteria

Cyanobacteria produce electrons through photosynthesis, where a fraction of these electrons are released to the external environment via electrogenic activity. According to the endosymbiotic theory, chloroplasts found in eukaryotes, such as algae and plants, evolved from cyanobacteria ancestors, thus studying the electron transport through cyanobacteria could improve the current knowledge of the photosynthesis process. We employ a variety of techniques, such as electrophysiology and electronic wiring, to extract information about the electrogenic activity of cyanobacteria at both the single cell level, and the ensemble level. In the process, we also explore the potential of directly extracting electricity from the renewable, abundant sources cyanobacteria. 

Dr UF Keyser

DNA Tug of War – Controlling and understanding DNA translocation and relaxation

Single DNA molecules can be inserted and controlled in a single solid-state nanopore. The DNA is driven into the pore by an electrical field in the nanopore. We are able to stall and control the translocation by grabbing the end of the DNA strand using optical tweezers. With this novel technique we study the influence of hydrodynamic interactions on the transport of DNA though these nanopores. We are investigating if it is possible to detect proteins bound to the DNA to determine the primary sequence. In addition, we work on extending the technique to single proteins and nucleic acids in biological nanopores.

Probing the force on DNA-protein complexes in a nanocapillary

Recently, we demonstrated for the first time the detection of the folding state of double-stranded DNA in nanocapillaries with the resistive pulse technique. We show that glass capillaries can be pulled into nanocapillaries with diameters down to 20 nm. We study translocation of DNA which is driven by an electrophoretic force through the nanocapillary. We would like to push the limits of the technique by detecting a single protein molecule on a DNA strand in a nanocapillary by combined measurements with optical tweezers and nanocapillary-based resistive-pulse sensing..

Mimicking protein channels in a chip

Transport of ions, metabolite molecules and macromolecular solutes across biological membranes is an ubiquitous process in nature. Specifically membrane proteins form metabolite-specific channels with large aqueous pores exhibiting affinities to their metabolites. Recently we have introduced a novel approach for the control, detection and manipulation of single nanoparticles by combining microfluidics with laser scattering and holographic optical tweezers. The aim of this project is to study the particle translocations through micro/nano-fluidic channels driven by concentration gradients or electro-osmotic/phoretic forces.

Membrane transport through E. coli and pure lipid membranes

Passive membrane transport is ubiquitous in living organism. One class of special interest are small organic compounds like indole. Our understanding of the roles of indole in bacterial signalling has grown rapidly in recent years. The list of processes in which indole participates is long and diverse. In many respects indole behaves like the signalling component of a quorum sensing system. Indole synthesised within the producer bacterium is exported into the surroundings where its accumulation is detected by sensitive cells. By direct observation of indole import into individual liposomes we have shown that indole can cross a lipid membrane without the aid of a proteinaceous transporter. These observations enhance our understanding of indole signalling in bacteria and, perhaps more importantly, provide a simple explanation for the ability of indole to signal between biological kingdoms.

Professor U Steiner

Block co-polymer based metamaterials

A metamaterial uses sub-wavelength building blocks that have resonant optical characteristics, mimicking atoms or molecules, but fabricated from metals into shapes such as rings, slots, voids, or plates. The resulting optical characteristics can then be described by a uniform complex dielectric constant but can exhibit negative refraction, super-refraction, electromagnetic cloaking, enhanced absorption/emission, and host of other phenomena. One of the greatest difficulties in constructing nanostructures in which the fundamental building blocks are much smaller than the wavelength of visible light, is the restricted technology available for their fabrication. The aim of this project is to synthesise materials with well controlled sub-wavelength structures which are formed by molecular self-assembly processes. These organic materials are used as scaffolds for the synthesis of optical metamaterials. The project is an interplay of material synthesis strategies and the optical characterisation of the resulting nano-structured specimen. This project is a collaboration with Prof. Jeremy Baumberg.

Non-equilibrium polymer morphologies in confinement

Polymers in thin films are technologically important in coatings but also in high-tech applications such as semiconductor lithography. As smaller and smaller structures become technologically relevant, the relatively large size of macomolecular molecules starts to paly a role. This project aims to develop a quantitative understanding how the physical properties of polymers changes upon confinement and how they depend on film preparation.

Structure-function relationship in organic photovoltaics

The performance of all-organic solar cells has substantially improved over the past 10 years, caused by advances in the synthesis of new materials and their assembly into photovoltaic devices. While the performance of the these devices depend on the detailed assembly of several component on the 10-nm length scale, only very little is know about how the 10-nm morphology of these materials influences the solar cell performance, and how these morphologies arise from the preparation of these devices. From a fundamental view, this is a very complex problem. It involves the interplay of polymer-polymer demixing with the crystallisation of the individual components. The purpose of this project is to make use of the current know-how in polymer science to gain a quantitative understanding in structure formation in photovoltaic blends, and the resulting photovoltaic performance. This project is collaboration with Prof. Richard Friend.

Butterfly photonics

The colour of butterfly wing scales arises mainly from the photonic structure in these scales. In contrast to pigment colour, these structural colours are particularly brilliant, and have interesting directional reflection and polarisation properties. As such, butterfly colours are interesting in the field of optical security labels (e.g. bank notes, passports), because they cannot be easily copied. This project entails the development of a manufacture strategy to generate a replica of the Morpho butterflies, which are among the optically most striking butterflies.

Professor E M Terentjev

The specific nature and details of proposed research are changing and evolving, so it is best to contact me directly about the current state of affairs. Some themes may continue from the work done in the past years:

Organic synthesis of new polymers and liquid crystalline systems

There is certainly a scope for a full PhD project in synthetic chemistry and material characterisation, based in our chemistry lab and supervised jointly with an experienced organic chemist. The aim here is to obtain new molecules with mechanical or photo-functionality, such as a new surfactant for the dispersion of carbon nanotubes in a given polymer, which would impart photo-mechanical or photo-electric response to the matrix.

Thermal, photo and electric actuators

Embedding orientationally ordered and aligned units into a rubbery matrix, and making them change their state on a given external stimulus, results in a spontaneous equilibrium mechanical actuation of the composite. Our group has over 10 years of history in this field, ranging from carbon nanotube composites to nematic liquid crystal elastomers. This project has a strong engineering and/or chemistry element because new materials need to be frequently produced. Present and near-future targets are in developing actuating fibres, micron-size shape-changing particles and large-area tactile displays.

Molecular and phase chirality by optical rotation

As with all other projects, this is a generic group of problems which combine theoretical and experimental issues related to the spontaneous formation of coherent (macro- or mesoscopic) structures with chiral nature. Familiar examples of these include d-helix of DNA and a-helix motif of protein folding, but there are many other structures in non-biological as well as living soft matter. One of the experimental methods to investigate the phase transformations that lead to such structures is the optical rotation, which is a developing instrument in the group.

Theoretical modelling of soft-matter and biological systems

The range of possible problems under this heading is large and constantly evolving: for instance, recently we were active in studying properties of semiflexible filaments and their network &emdash; both from the point of views of their growth kinetics (related, for instance, to the amyloid fibrils or actin cytoskeleton) and the resulting dynamic-mechanical properties. Another problem with good prospects for the future is modelling cell adhesion and mobility by combining the stochastic dynamics of Kramers-like systems with our understanding of gel viscoelasticity, leading to the modelling mechanosensitivity of cells (the response to external forces or mechanical constraints).

Dr A Zaccone

Theory of amorphous materials

Amorphous materials (e.g. glass) differ from their crystalline (ordered) counterparts in that the atomic or molecular arrangements do not follow the regular patterns of a lattice (where every atom occupies a site of inversion on the lattice) but are more or less randomly organized in space. This fundamental fact has a lot of consequences when we consider the macroscopic properties of these solids, such as their elastic moduli or their electronic conduction and optical properties, in comparison with the crystalline counterparts. We are working on developing a theoretical understanding of the thermoelastic deformation behaviour of amorphous materials in an effort to explain puzzling features, such as the relative softness with respect to crystals and the possibility that they undergo a transition into liquid states without crossing any equilibrium thermodynamic phase boundary (this is the so called glass transition problem). Applications range from metallic glasses to polymers and inorganic glasses. Recently we are developing an interest for disorder-related problems in the electronic conduction of polymers with application to solar energy devices. This project is in collaboration with Prof E M Terentjev.

Dynamics and kinetics of Brownian systems

Particles in the size range between a few nanometers and a few microns suspended in a liquid exhibit a peculiar type of dynamics called Brownian motion whereby they move randomly in the environment under the influence of many microscopic collisions with the solvent molecules. In many systems of both practical (e.g. nanotechnology) and biological (e.g. proteins) interest, Brownian motion plays a role in conjunction with other types of forces such as hydrodynamics (e.g. shear flow), electrostatic and dispersion forces, osmotic forces etc. The interplay of all these forces controls the aggregation and phase behaviour of colloidal Brownian systems which is reflected in the evolution of the macroscopic properties (e.g. rheology, optical properties etc). By working with diffusion-type equations we aim at incorporating this complexity into a unifying framework that can be used to rationalize the phase behaviour, macroscopic properties and phase transitions of colloidal systems such as nanoparticle and protein suspensions. This project is in close collaboration with several experimental groups, including Dr E Eiser (BSS) and Prof A Donald (BSS) as well as other groups in Germany and Switzerland.

BSS - Postgraduate Admissions