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Washington University in St Louis

Washington University in St Louis

16 Projects, page 1 of 4
  • Funder: UK Research and Innovation Project Code: EP/V034154/2
    Funder Contribution: 720,194 GBP

    Liquid infused surfaces (LIS) are a novel class of surfaces inspired by nature (pitcher plants) that repel any kind of liquid. LIS are constructed by impregnating rough, porous or textured surfaces with wetting lubricants, thereby conferring them advantageous surface properties including self-cleaning, anti-fouling, and enhanced heat transfer. These functional surfaces have the potential to solve a wide range of societal, environmental and industrial challenges. Examples range from household food waste, where more than 20% is due to packaging and residues; to mitigating heat exchanger fouling, estimated to be responsible for 2.5% of worldwide CO2 emissions. Despite their significant potential, however, to date LIS coatings are not yet viable in practice for the vast majority of applications due to their lack of robustness and durability. At a fundamental level, the presence of the lubricant gives rise to a novel but poorly understood class of wetting phenomena due to the rich interplay between the thin lubricant film dynamics and the macroscopic drop dynamics, such as an effective long-range interaction between droplets and delayed coalescence. It also leads to numerous open challenges unique to LIS, such as performance degradation due to lubricant depletion. Integral to this EPSRC Fellowship project is an innovative numerical approach based on the Lattice Boltzmann method (LBM) to solve the equations of motion for the fluids. A key advantage of LBM is that key coarse-grained molecular information can be incorporated into the description of interfacial phenomena, while remaining computationally tractable to study the macroscopic flow dynamics relevant for LIS. LBM is also highly flexible to account for changes in the interface shape and topology, complex surface geometry, and it is well-suited for high performance computing. The developed simulation framework will be the first that can fully address the complexity of wetting dynamics on LIS, and the code will be made available open source through OpenLB. Harnessing the LBM simulations and supported by experimental data from four project partners, I will provide the much-needed step change in our understanding of LIS. The expected outcomes include: (i) design criteria that minimise lubricant depletion, considered the main weakness of LIS; (ii) new insights into droplet and lubricant meniscus dynamics on LIS across a wide range of lubricant availability and wettability conditions; and (iii) quantitative models for droplet interactions on LIS mediated by the lubricant. These key challenges are shared by the majority, if not all, of LIS applications. Addressing them is the only way forward to better engineer the design of LIS. Finally, the computational tools and fundamental insights developed in the project will be exploited to explore two potentially disruptive technologies based on LIS, which are highly relevant for the energy-water-environment nexus in sustainable development. First, I will investigate application in carbon capture, exploiting how liquids can be immobilised in LIS with a large surface to volume ratio, in collaboration with ExxonMobil. More specifically, liquid amine-based CO2 capture is an important and commercially practised method, but the costly infrastructure and operation prohibit its widespread implementation. Excitingly, LIS may provide a solution to a more economical carbon capture method using liquid amine. Second, motivated by the current gap of 47% in global water supply and demand, as well as environmental pressure to reduce the use of surfactants, I will examine new approaches to clean in collaboration with Procter & Gamble. The key idea is to induce dewetting of unwanted liquid droplets on solid surfaces using a thin film of formulation liquid, thus introducing wettability alteration more locally and using much reduced resources.

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  • Funder: UK Research and Innovation Project Code: NE/L006065/1
    Funder Contribution: 726,620 GBP

    We aim to decrease the uncertainty associated with the measurement of ice mass change in West Antarctica by addressing our lack of knowledge of Earth structure and accuracy of present-day uplift rates. Ice loss from the West Antarctic Ice Sheet (WAIS) currently accounts for around 10% of present-day global sea-level rise. Moreover, this region is undergoing accelerated ice loss. Accurate projections for the evolution of WAIS are currently hindered by uncertainties in measurements of present-day ice mass change. Two key methods for deriving this change are satellite gravimetry, which determines changes in Earth's gravity field due to surface mass redistribution, and altimetry, which measures modifications to the height of the ice surface. Crucially, both of these techniques are susceptible to errors introduced by correcting for the uplift response of the solid Earth to past ice mass loss, a process known as Glacial Isostatic Adjustment (GIA). GIA models require information relating to the regional deglaciation history and the rheological properties of the solid Earth. In most GIA models only 1D global averages of Earth structure are taken in to account; this is a gross oversimplification. We propose to determine (i) 3D Earth structure in West Antarctica and Antarctic Peninsula through a new passive seismological experiment and (ii) present-day uplift rates through the extension of a NERC-funded GPS network in the Peninsula and new spatially extensive satellite radar interferometry data (InSAR). We will deploy 10 broadband seismometers for 2 years, adjacent to a contemporaneous 2 year POLENET deployment, to estimate 3D variations in Earth rheology by determining S-wave velocity-depth models down to depths of 400 km. Seismic data have never been collected in the southern Antarctic Peninsula region of West Antarctica, and hence very little is known about its Earth structure. The determination of lithospheric structure will also improve our understanding of the tectonic evolution of the region. We propose a 3 year PDRA to carry out the fieldwork and seismological research. Long time series of surface deformation measurements are important to our understanding of uplift rates due to GIA. A network of 10 GPS sites has been deployed in the southern Antarctic Peninsula since 2009 under a now terminating NERC/AFI grant. At minor additional financial cost, but with significant scientific benefit, we propose to operate this network for a further 2 years. Our Project Partner Matt King (University of Tasmania) will oversee the processing of these data. The seismic structure results will be incorporated into a 3D GIA model as an addition to CI Whitehouse's Fellowship work; a 1.5 year PDRA will combine the GIA and deformation results to more tightly constrain past and present ice mass change in the southern Antarctic Peninsula and West Antarctica. While the sparse network of GPS will constrain the deformation pattern on a broad scale, we expect smaller wavelength variability in deformation due to present-day ice mass change. Therefore, we plan to apply satellite radar interferometry (InSAR) to the rock outcrops in West Antarctica to increase the spatial sampling of the deformation field by orders of magnitude. Because distances between rock outcrops can be large, the spatial variability of the tropospheric radar propagation delay during interferometric processing has to be estimated from weather models. We propose to test these assumptions with a local field deployment of 6 GPS in the Antarctic Peninsula. The timing of this grant proposal is critical as 1) BAS logistics are already in place for the funded 2 year iStar programme in the south of the region; 2) US POLENET seismometers will temporarily be positioned to the south and significantly extend our station coverage; 3) the grant supporting the GPS network is ending.

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  • Funder: UK Research and Innovation Project Code: EP/V034154/1
    Funder Contribution: 1,151,140 GBP

    Liquid infused surfaces (LIS) are a novel class of surfaces inspired by nature (pitcher plants) that repel any kind of liquid. LIS are constructed by impregnating rough, porous or textured surfaces with wetting lubricants, thereby conferring them advantageous surface properties including self-cleaning, anti-fouling, and enhanced heat transfer. These functional surfaces have the potential to solve a wide range of societal, environmental and industrial challenges. Examples range from household food waste, where more than 20% is due to packaging and residues; to mitigating heat exchanger fouling, estimated to be responsible for 2.5% of worldwide CO2 emissions. Despite their significant potential, however, to date LIS coatings are not yet viable in practice for the vast majority of applications due to their lack of robustness and durability. At a fundamental level, the presence of the lubricant gives rise to a novel but poorly understood class of wetting phenomena due to the rich interplay between the thin lubricant film dynamics and the macroscopic drop dynamics, such as an effective long-range interaction between droplets and delayed coalescence. It also leads to numerous open challenges unique to LIS, such as performance degradation due to lubricant depletion. Integral to this EPSRC Fellowship project is an innovative numerical approach based on the Lattice Boltzmann method (LBM) to solve the equations of motion for the fluids. A key advantage of LBM is that key coarse-grained molecular information can be incorporated into the description of interfacial phenomena, while remaining computationally tractable to study the macroscopic flow dynamics relevant for LIS. LBM is also highly flexible to account for changes in the interface shape and topology, complex surface geometry, and it is well-suited for high performance computing. The developed simulation framework will be the first that can fully address the complexity of wetting dynamics on LIS, and the code will be made available open source through OpenLB. Harnessing the LBM simulations and supported by experimental data from four project partners, I will provide the much-needed step change in our understanding of LIS. The expected outcomes include: (i) design criteria that minimise lubricant depletion, considered the main weakness of LIS; (ii) new insights into droplet and lubricant meniscus dynamics on LIS across a wide range of lubricant availability and wettability conditions; and (iii) quantitative models for droplet interactions on LIS mediated by the lubricant. These key challenges are shared by the majority, if not all, of LIS applications. Addressing them is the only way forward to better engineer the design of LIS. Finally, the computational tools and fundamental insights developed in the project will be exploited to explore two potentially disruptive technologies based on LIS, which are highly relevant for the energy-water-environment nexus in sustainable development. First, I will investigate application in carbon capture, exploiting how liquids can be immobilised in LIS with a large surface to volume ratio, in collaboration with ExxonMobil. More specifically, liquid amine-based CO2 capture is an important and commercially practised method, but the costly infrastructure and operation prohibit its widespread implementation. Excitingly, LIS may provide a solution to a more economical carbon capture method using liquid amine. Second, motivated by the current gap of 47% in global water supply and demand, as well as environmental pressure to reduce the use of surfactants, I will examine new approaches to clean in collaboration with Procter & Gamble. The key idea is to induce dewetting of unwanted liquid droplets on solid surfaces using a thin film of formulation liquid, thus introducing wettability alteration more locally and using much reduced resources.

    more_vert
  • Funder: UK Research and Innovation Project Code: BB/L002604/1
    Funder Contribution: 476,159 GBP

    Understanding how the genome makes the traits we observe in individuals (i.e., their 'phenotype') is perhaps the most fundamental problem in biology. Achieving such an understanding has been challenging because there are many pathways from the genome to the traits we observe, and those traits themselves can be complex and 'multidimensional', being made up of suites of traits that are tied together through the shared process of development controlled by a shared genome. The shared genomic and developmental bases generally contribute to associations between traits, where the expression of one trait is correlated to the expression of other traits. Such associations between traits play a major role in evolutionary processes because they make the evolutionary fate of one trait tied to the fate of other traits. Furthermore, the success of an individual (i.e., their 'Darwinian fitness') is a product of all of their traits, operating in concert, and hence natural selection can favour particular combinations of traits and thereby shape the relationship between traits. We propose to examine the genetic basis and evolution of these associations between traits by studying populations of mice that have evolved differences in their patterns of growth in response to artificial selection (selective breeding for different growth patterns). The eight populations we are focusing on were generated by four different patterns of artificial selection that altered their rate of growth early and late in postnatal development. This resulted in a series of growth patterns that are novel and the relationship between early and late growth is different to the pattern seen in the starting generation. To understand how selection has changed the relationship between growth traits, and how these changes in development, in turn, alter the nature of variation seen at the endpoint of development in adult traits, we will mix the genomes of populations from these eight selection lines. Using this mixed population, we will ask 'how having inherited regions of the genome from these evolutionarily divergent populations allowed patterns of growth to become 'reshaped' by selection?'. We will look at the overall patterns of how these genomic regions 'map' to phenotypes (i.e., how they influence the overall pattern of traits expressed by individuals) as well as complex interactions between regions of the genome that together determine the pattern of growth and patterns of variation in complex adult phenotypes. We will also ask 'what role have changes in maternal traits played in altering patterns of growth in their offspring?'. We already know that something has changed in the way that mothers influence the growth of their offspring, but we do not know whether changes in these maternal influences led to evolutionary changes in the direction favoured by selection or whether they contributed 'maladaptive' changes opposing the direction favoured by selection. We will integrate all of the information we accumulate on how genomes build the traits we observe to develop a better understanding of how evolution proceeds at the molecular level, and how these genetic changes allowed selection to reshape patterns of growth and development. We will then link these developmental changes to the patterns of variation produced as the output of development in adults to understand how shifting growth patterns impacts the patterns of genetic variation that are produced as the output of the developmental process.

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  • Funder: UK Research and Innovation Project Code: EP/P030815/1
    Funder Contribution: 100,798 GBP

    The transformation of energy in the forms of heat and work pertains to everyday life and is a crucial aspect in the efficiency of machines. In fact, the laws of thermodynamics, which govern these energy transformations, are so fundamental that have their say in almost all branches of physics. The first law acknowledges that heat is energy to be accounted for in energy conservation. The second law of thermodynamics qualitatively distinguishes heat from other forms of energy by associating it to entropy, a measurement of the "lack of information" about a system, and by stating that entropy grows in macroscopic systems. The generality of these statements stems from general statistical properties of macroscopic objects with a large number of degrees of freedoms. However, the technological advances in engineering and operating nanoscale objects like molecular machines, forces us to rethink the implications of thermodynamics for microscopic few-particle systems, where thermal fluctuations are significant. Here the laws of thermodynamics can be reformulated in terms of probabilistic equations, known as fluctuation theorems, which account for rare microscopic events, like those where entropy decreases, which are instead washed away by statistics in the macroscopic word. The formulation and experimental verification of these theorems have been a success of stochastic thermodynamics in the past decade. The nanoscale world, however, challenges us further with quantum mechanical processes emerging at this scale, and devices built upon them. How do we include quantum fluctuations into the laws of thermodynamics? Current research is advancing on this front with some success by analyzing quantum machines operating between classical thermal sources, to identify genuine quantum effects and generalize the definitions of heat and work for quantum processes. The main problem is that in quantum mechanics even measuring the energy of an isolated system is a deterministic process, and that measuring a specified variable, e.g. work along quantum evolution, comes with unavoidable back-action that needs to be taken into account. In this project, we set aside the usual thermodynamic setup where a system is coupled to a thermal bath and focus instead on the measurement process, where a detector monitoring the system is the reservoir with which the system exchanges energy. This kind of configuration allows us to focus on the role of quantum measurement, and it brings new aspects into play, like the fact of dealing with an out-of-equilibrium environment, and the thermodynamic role of the information gained during the measurement. It also comes with the possibility of short-term experimental realizations, since quantum detector's readout is experimentally available, as opposed to thermal baths' readout. The project will set-up the tools to deal with the thermodynamics of quantum measurement and use them to engineer heat flow detectors and possibly heat flow engineering at the nanoscale.

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