The synthesis of polymeric materials as living and self-healing systems.

Advancements in smarter materials will play a major role in reducing materials, energy use, pollution, and carbon emissions. This creates a need for research to devise new composite materials incorporating the latest technologies in fields such as whole-cell catalysts and self-healing methods to create biocomposite materials. Functional biocomposite materials can be produced by depositing immobilised microorganisms onto a surface of a substrate material in a flexible, non-porous polymer which can sustain living cells. Ideally these biocoatings should be easy to apply using manual draw down techniques or by ink-jet printing for well-defined patterns and show activity rates at least comparable with free-floating cells. The focus of this thesis was to create a method for the development of multichannel 3D substrates, embedding immobilised cells within a polymer matrix to create a multifunctional bioactive coating. To achieve this, a latex polymer coating was synthesised using styrene, butyl acrylate and acrylic acid. This composition was adjusted to create several latex polymer samples with varying physical properties. Increases in styrene content correlated directly to increasing glass transition temperature and hardness. Latex polymers were subject to coalescing agents to enhance film formation and reported small changes in coating properties. Several feasible substrates were coated and analysed for adhesion and surface coverage, the highest performing were implemented into biocatalysis reaction assays. Assays when compared to equivalent cell suspension systems reported reaction rates up to five times that of suspended yeast cells. Distribution of cells were analysed using fluorescent E. coli under confocal and scanning electron microscopes. The development of these techniques enabled the analysis of BL21 (DE3) competent E. coli cells containing a pOPINF plasmid to be immobilised into the co-polymer coating and cell survival measured through expression of a green fluorescent protein. Latex polymer composites were used to immobilise two strains of cyanobacteria. S. elongatus PCC 7942 and CCAP 1479/1A were tested on loofah substrates for toxicity, adhesion, net CO2 fixation rates and biological responses. CO2 uptake was found to increase by 19 - 22 and 4 - 7-fold for CCAP 1479/1A and PCC 7942 for the best performing biocomposites relative to their suspension controls. While immobilized, CCAP biocomposites survived in excess of 12 weeks, however PCC 7942 biocomposites experienced cell leaching after 4 weeks. A complex and high-resolution piezoelectric ink-jet printer was used to deposit small (<50 μm) latex-cell droplets onto a 3D laser-cut scaffold of a polyacrylic material which created a channeled network reactor. A continuous flow circuit was created and tested using a standard cell assay. In parallel, a suite of self-healing polyurethane samples were synthesised and the optimal composition of alcohols and diisocyanate monomers investigated. To measure self-healing capabilities polyurethane samples were cut and rejoined after 1 and 24 hours. Samples were analysed using tensile strength testing and compared to identical uncut samples. The polymer was found to retain between of 63 - 98 % (after 24 h) and 33 - 61 % (after 1 h) of its uncut strength

Promoting dietary changes for achieving health and sustainability targets

Globally, about 21–37% of total greenhouse gas (GHG) emissions are attributable to food systems. Dietary-related non-communicable diseases have increased significantly from 1990–2019 at a global scale. To achieve carbon emissions targets, increase resilience, and improve health there is a need to increase the sustainability of agricultural practises and change dietary habits. By considering these challenges together and focusing on a closer connection between consumers and sustainable production, we can benefit from a positive interaction between them. Using the 2019 EAT Lancet Commission dietary guidelines, this study analysed interview data and food diaries collected from members of Community Supported Agriculture (CSA) schemes and the wider UK population. By comparing the environmental sustainability and nutritional quality of their respective diets, we found that CSA members consumed diets closer to the EAT Lancet recommendations than controls. We identified significant differences in daily intakes of meat; dairy; vegetables; legumes; and sugar, and the diets of CSA members emitted on average 28% less CO2 compared to controls. We propose that agricultural and wider social and economic policies that increase the accessibility of CSAs for a more diverse demographic could support achieving health, biodiversity, and zero-emission policy targets

Diversity of woody-host infecting Phytophthora species in public parks and botanic gardens as revealed by metabarcoding, and opportunities for mitigation through best practice

The diversity of Phytophthora species in soils collected from 14 highly disturbed sites in northern Britain, including botanic gardens, arboreta, public parks and other amenity woodland sites, was analysed using a molecular technique known as DNA metabarcoding. This technique enables the identification of multiple species present in a single environmental sample based on a DNA ‘barcode’ unique to each species. The genus Phytophthora was targeted in this study due to its increasing impact on Britain’s forests and woodlands over thelast 20 years. The introduction and spread of new Phytophthora species into Britain has been strongly associated with the movement of traded containerised plants, with a number of Phytophthora outbreaks reported on host trees located in public gardens and parks that had recently undergone planting or landscape regeneration schemes. This study was undertaken to assess the extent to which these highly disturbed sites with extensive planting regimes act as harbours for woody-host infecting Phytophthora species. A total of 23 Phytophthora species, the majority of which are known to be pathogens of woody hosts, were detected across the 14 sites sampled. These included four quarantine-regulated pathogens and four species notpreviously recorded in Britain. Also detected were three as-yet undescribed Phytophthora species and nine oomycete sequences with no clear match to any known genus. There was no effect of geographical location, elevation, underlying soil type, host family or host health status on the Phytophthora assemblages at each site, suggesting that the Phytophthora communities detected are likely to comprise introduced species associated with planting programmes. P. austrocedri and P. pseudosyringae were two of the most abundant Phytophthoraspecies detected, both of which cause serious damage to trees and are regarded as fairly recent introductions to Britain. The practical implications of the findings in terms of mitigating Phytophthora introduction, spread and impact at botanic gardens, arboreta and urban parks are discussed

Engineered living photosynthetic biocomposites for intensified biological carbon capture

Carbon capture and storage is required to meet Paris Agreement targets. Photosynthesis is nature’s carbon capture technology. Drawing inspiration from lichen, we engineered 3D photosynthetic cyanobacterial biocomposites (i.e., lichen mimics) using acrylic latex polymers applied to loofah sponge. Biocomposites had CO2 uptake rates of 1.57 ± 0.08 g CO2 g−1biomass d−1. Uptake rates were based on the dry biomass at the start of the trial and incorporate the CO2 used to grow new biomass as well as that contained in storage compounds such as carbohydrates. These uptake rates represent 14–20-fold improvements over suspension controls, potentially scaling to capture 570 tCO2 t−1biomass yr−1, with an equivalent land consumption of 5.5–8.17 × 106 ha, delivering annualized CO2 removal of 8–12 GtCO2, compared with 0.4–1.2 × 109 ha for forestry-based bioenergy with carbon capture and storage. The biocomposites remained functional for 12 weeks without additional nutrient or water supplementation, whereupon experiments were terminated. Engineered and optimized cyanobacteria biocomposites have potential for sustainable scalable deployment as part of humanity’s multifaceted technological stand against climate change, offering enhanced CO2 removal with low water, nutrient, and land use penalties

Hypotheses for the Origin of the Hypanis Fan-Shaped Deposit at the Edge of the Chryse Escarpment, Mars: Is it a Delta?

We investigated the origin of the fan-shaped deposit at the end of Hypanis Valles that has previously been proposed as an ExoMars, Mars 2020, and human mission candidate landing site, and found evidence that the landform is an ancient delta. Previous work suggests that the deposit originated from a time of fluvial activity both distinct from and prior to catastrophic outflow, and crater counting placed the deposit’s age at  ≥ 3.6 Ga. We found over 30 thin sedimentary strata in the proposed delta wall, and from our slope analysis conclude that the fluvial sequence is consistent with a lowering/retreating shoreline. We measured nearly horizontal bedding dip angles ranging from 0° to 2° over long stretches of cliff and bench exposures seen in HiRISE images and HiRISE stereo DTMs. From THEMIS night IR images we determined that the fan-shaped deposit has a low thermal inertia (150-240 Jm-2 K-1 s-1/2) and the surrounding darker-toned units correspond to thermal inertia values as high as 270-390 Jm-2 K-1 s-1/2. We interpret these findings to indicate that the fan-shaped deposit consists mostly of silt-sized and possibly finer grains, and that the extremely low grade and large lateral extent of these beds implies that the depositional environment was calm and relatively long-lived. We interpret the geomorphology and composition as incompatible with an alluvial fan or mudflow hypothesis. From our stratigraphic mapping we interpret the order of events which shaped the region. After the Chryse impact, sediment filled the basin, a confined lake or sea formed allowing a large delta to be deposited near its shoreline, the water level receded to the north, darker sedimentary/volcanic units covered the region and capped the light-toned deposit as hydro-volcanic eruptions shaped the interior of Lederberg crater, freeze/thaw cycles and desiccation induced local fracturing, and finally wrinkle ridges associated with rounded cones warped the landscape following trends in degraded crater rims and existing tectonic features. The ancient deltaic deposit we observe today was largely untouched by subsequent catastrophic outflows, and its surface has been only moderately reshaped by over 3 billion years of aeolian erosion

Immobilising Microalgae and Cyanobacteria as Biocomposites: New Opportunities to Intensify Algae Biotechnology and Bioprocessing

There is a groundswell of interest in applying phototrophic microorganisms, specifically microalgae and cyanobacteria, for biotechnology and ecosystem service applications. However, there are inherent challenges associated with conventional routes to their deployment (using ponds, raceways and photobioreactors) which are synonymous with suspension cultivation techniques. Cultivation as biofilms partly ameliorates these issues; however, based on the principles of process intensification, by taking a step beyond biofilms and exploiting nature inspired artificial cell immobilisation, new opportunities become available, particularly for applications requiring extensive deployment periods (e.g., carbon capture and wastewater bioremediation). We explore the rationale for, and approaches to immobilised cultivation, in particular the application of latex-based polymer immobilisation as living biocomposites. We discuss how biocomposites can be optimised at the design stage based on mass transfer limitations. Finally, we predict that biocomposites will have a defining role in realising the deployment of metabolically engineered organisms for real world applications that may tip the balance of risk towards their environmental deployment

Implications and impacts of aligning regional agriculture with a healthy diet

One of the most intractable challenges currently facing agricultural systems is the need to produce sufficient food for all to enjoy a healthy balanced diet while minimising impacts to the environment. Balancing these competing goals is especially intractable because most food systems are not locally bounded. This study aims to investigate the likely impacts on production, profit and the environment that result from aligning food systems to a healthy diet, as defined by EAT-Lancet. For this, we consider two distinct areas of the UK, one in East Anglia and the other in South Wales. These two regions reflect different ecosystems and therefore differing specialisations in UK agriculture. We used the Rothamsted Landscape Model (a detailed agroecosystems process-based model) to predict soil carbon dynamics, nutrient flows and crop production for the dominant crops grown in these regions, and the IPCC inventory models to estimate emissions from six livestock systems. Two scenarios were considered, one in which the study regions had to meet healthy diet requirements independently of each other and another in which they could do so collectively. To map their production to healthy diets, both study areas require increases in the production of plant proteins and reductions in the production of red meat. While changes in production can feed more people a healthy diet compared to the business-as-usual state, the overall calories produced reduces dramatically. Emissions and leaching decrease under the healthy diet scenarios and pesticide impacts remain largely unchanged. We show that local infrastructure and environment have a bearing on how “localised” food systems can be without running into substantial constraints. Whilst isolation of the farming system to a regional level, as explored here, is unlikely to be practical, we nevertheless demonstrate that aligning agricultural production towards healthier diets can generate food systems with many associated benefits in terms of agroecosystems' health and resilience to shocks in the food supply chain

Metabarcoding reveals a high diversity of woody host-associated Phytophthora spp. in soils at public gardens and amenity woodlands in Britain

This work was supported by Forestry Commission Scotland (grant number SLA-14/15-034), the Living With Environmental Change Phase 3 project ‘Phyto-Threats’ as part of the Tree Health and Plant Biosecurity Initiative (grant number BB/N023463/1) and the European Union’s Horizon 2020 research and innovation programme POnTE (Pest Organisms Threatening Europe) (grant number 635646). David E.L. Cooke, Pete E. Hedley, Leighton Pritchard, Peter Thorpe also received funding from the Scottish GovernmentForests and woodlands worldwide are being severely impacted by invasive Phytophthora species, with initial outbreaks in some cases occurring on host trees located in public parks and gardens. These highly disturbed sites with diverse planting practices may indeed act as harbours for invasive Phytophthora pathogens which are particularly well adapted to surviving in soil. High throughput Illumina sequencing was used to analyse Phytophthora species diversity in soil samples collected from 14 public garden/amenity woodland sites in northern Britain. Bioinformatic analyses revealed some limitations to using internal transcribed spacer as the barcode region; namely reporting of false positives and ambiguous species matches. Taking this into account, 35 distinct sequences were amplified across the sites, corresponding to 23 known Phytophthora species as well as twelve oomycete sequences with no match to any known Phytophthora species. Phytophthora pseudosyringae and P. austrocedri, both of which cause serious damage to trees and are regarded as fairly recent introductions to Britain, were the two most abundant Phytophthora species detected. There was no evidence that any of the detected Phytophthora species were more associated with any one type of host, healthy or otherwise. This study has demonstrated the ubiquity and diversity of Phytophthora species endemic in highly managed, extensively planted soil environments in Britain. Suggested improvements to the methodology and the practical implications of the findings in terms of mitigating Phytophthora spread and impact are discussed.Publisher PDFPeer reviewe

Lithium Transport in Li4.4M0.4M ' S-0.6(4) (M = Al3+, Ga3+, and M ' = Ge4+, Sn4+): Combined Crystallographic, Conductivity, Solid State NMR, and Computational Studies

In order to understand the structural and compositional factors controlling lithium transport in sulfides, we explored the Li5AlS4 – Li4GeS4 phase field for new materials. Both parent compounds are defined structurally by a hexagonal close packed sulfide lattice, where distinct arrangements of tetrahedral metal sites give Li5AlS4 a layered structure and Li4GeS4 a three dimensional structure related to γ-Li3PO4. The combination of the two distinct structural motifs is expected to lead to new structural chemistry. We identified the new crystalline phase Li4.4Al0.4Ge0.6S4, and investigated the structure and Li+ ion dynamics of the family of structurally related materials Li4.4M0.4M’0.6S4 (M= Al3+, Ga3+ and M’= Ge4+, Sn4+). We used neutron diffraction to solve the full structures of the Al-homologues, which adopt a layered close-packed structure with a new arrangement of tetrahedral (M/M’) sites and a novel combination of ordered and disordered lithium vacancies. AC impedance spectroscopy revealed lithium conductivities in the range 3(2) x 10-6 to 4.3(3) x 10-5 S cm-1 at room temperature with activation energies between 0.43(1) and 0.38(1) eV. Electrochemical performance was tested in a plating and stripping experiment against Li metal electrodes and showed good stability of the Li4.4Al0.4Ge0.6S4 phase over 200 hours. A combination of variable temperature 7Li solid state nuclear magnetic resonance spectroscopy and ab initio molecular dynamics calculations on selected phases showed that two dimensional diffusion with a low energy barrier of 0.17 eV is responsible for long-range lithium transport, with diffusion pathways mediated by the disordered vacancies while the ordered vacancies do not contribute to the conductivity. This new structural family of sulfide Li+ ion conductors offers insight into the role of disordered vacancies on Li+ ion conductivity mechanisms in hexagonally close packed sulfides that can inform future materials design

Bio-inspired geotechnical engineering: Principles, current work, opportunities and challenges

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