Towards the knittability of graphene oxide fibres

Recent developments in graphene oxide fibre (GO) processing include exciting demonstrations of hand woven textile structures. However, it is uncertain whether the fibres produced can meet the processing requirements of conventional textile manufacturing. This work reports for the first time the production of highly flexible and tough GO fibres that can be knitted using textile machinery. The GO fibres are made by using a dry-jet wet-spinning method, which allows drawing of the spinning solution (the GO dispersion) in several stages of the fibre spinning process. The coagulation composition and spinning conditions are evaluated in detail, which led to the production of densely packed fibres with near-circular cross-sections and highly ordered GO domains. The results are knittable GO fibres with Young\u27s modulus of ~7.9 GPa, tensile strength of ~135.8 MPa, breaking strain of ~5.9%, and toughness of ~5.7 MJ m(-3). The combination of suitable spinning method, coagulation composition, and spinning conditions led to GO fibres with remarkable toughness; the key factor in their successful knitting. This work highlights important progress in realising the full potential of GO fibres as a new class of textile

An Actuarial Analysis of Calibration of Crop Insurance Premiums to Heterogeneous Risks

This paper examines whether the loadings on the crop insurance premium rates for risks such as moral hazard and adverse selection are adequate. From the discrete choice (tobit) analysis conducted, we discover that the premium loadings for 75% coverage level are not adequate, resulting in losses for the Risk Management Agency

Relationship between nanotopographical alignment and stem cell fate with live imaging and shape analysis

The topography of a biomaterial regulates cellular interactions and determine stem cell fate. A complete understanding of how topographical properties affect cell behavior will allow the rational design of material surfaces that elicit specified biological functions once placed in the body. To this end, we fabricate substrates with aligned or randomly organized fibrous nanostructured topographies. Culturing adipose-derived stem cells (ASCs), we explore the dynamic relationship between the alignment of topography, cell shape and cell differentiation to osteogenic and myogenic lineages. We show aligned topographies differentiate cells towards a satellite cell muscle progenitor state - a distinct cell myogenic lineage responsible for postnatal growth and repair of muscle. We analyze cell shape between the different topographies, using fluorescent time-lapse imaging over 21 days. In contrast to previous work, this allows the direct measurement of cell shape at a given time rather than defining the morphology of the underlying topography and neglecting cell shape. We report quantitative metrics of the time-based morphological behaviors of cell shape in response to differing topographies. This analysis offers insights into the relationship between topography, cell shape and cell differentiation. Cells differentiating towards a myogenic fate on aligned topographies adopt a characteristic elongated shape as well as the alignment of cells

Implementation of multimodal computed tomography in a telestroke network : five-year experience

Aims: Penumbral selection is best-evidence practice for thrombectomy in the 6-24 hour window. Moreover, it helps to identify the best responders to thrombolysis. Multimodal computed tomography (mCT) at the primary centre—including noncontrast CT, CT perfusion, and CT angiography—may enhance reperfusion therapy decision-making. We developed a network with five spoke primary stroke sites and assessed safety, feasibility, and influence of mCT in rural hospitals on decision-making for thrombolysis. Methods: Consecutive patients assessed via telemedicine from April 2013 to June 2018. Clinical outcomes were measured, and decision-making compared using theoretical models for reperfusion therapy applied without mCT guidance. Symptomatic intracranial hemorrhage (sICH) was assessed according to Safe Implementation of Treatments in Stroke Thrombolysis Registry criteria. Results: A total of 334 patients were assessed, 240 received mCT, 58 were thrombolysed (24.2%). The mean age of thrombolysed patients was 70 years, median baseline National Institutes of Health Stroke Scale was 10 (IQR 7-18) and 23 (39.7%) had a large vessel occlusion. 1.7% had sICH and 3.5% parenchymal hematoma. Three months poststroke, 55% were independent, compared with 70% in the non-thrombolysed group. Conclusion: Implementation of CTP in rural centers was feasible and led to high thrombolysis rates with low rates of sICH. © 2019 The Authors. CNS Neuroscience & Therapeutics Published by John Wiley & Sons Ltd

Determining crystal structures through crowdsourcing and coursework

We show here that computer game players can build high-quality crystal structures. Introduction of a new feature into the computer game Foldit allows players to build and real-space refine structures into electron density maps. To assess the usefulness of this feature, we held a crystallographic model-building competition between trained crystallographers, undergraduate students, Foldit players and automatic model-building algorithms. After removal of disordered residues, a team of Foldit players achieved the most accurate structure. Analysing the target protein of the competition, YPL067C, uncovered a new family of histidine triad proteins apparently involved in the prevention of amyloid toxicity. From this study, we conclude that crystallographers can utilize crowdsourcing to interpret electron density information and to produce structure solutions of the highest quality

Electrochemical detection of microorganisms using conducting polymers

The rapid detection of microorganisms in the food, pharmaceutical, clinical medicine, environmental and agricultural industries is of the utmost importance. Unfortunately, the best current technology has been able to offer is detection times of several days for quantitative results. The development of conducting polymer films has led to an increase in research activity involving the use of these materials for the design and application of sensors. Their ability to undergo electrochemical switching between oxidised and reduced states, which is correlated with the movement of anions and cations, has seen conducting polymers successfully used to produce electrochemical responses for particular species of interest. Conducting polymers can also be used as a matrix for the immobilisation of biological components such as enzymes, proteins or antibodies. The immobilisation of these components adds specificity to the sensors. It the combination of a biological component, immobilised onto a suitable transducer, that is the basis of the expanding field of biosensor research. Recent successes in biosensor research have resulted in reduced detection times of the order of minutes or hours. The main disadvantage of these techniques however, has been the inability to successfully detect small viable numbers (\u3c104 microorganisms/ml (mo/ml) in these short periods of time. The focus of this work was the development of a technique suitable for the rapid and quantitative detection of a particular microorganism, Listeria monocytogenes. Chapter 3 investigated the incorporation of an antibody into a conducting polymer matrix. A comparison of various immobilisation techniques including physical entrapment, co-immobilisation and covalent attachment of the biological component was undertaken. It was found that the covalent attachment method provided films with more reproducibility and sensitivity compared to those prepared by the other methods. In Chapter 4, an investigation into signal generation is described. Conventional electrochemistry and the comparison of two different resistometric methods were investigated. It has been suggested that resistance measurements offer greater sensitivity than amperometric or potentiometric detection methods, however this was found not to be true in this instance. A lack of reproducibility and a high detection limit was the limiting factor in this work, so an alternative signal generation method was considered. Conventional mediators were trialled to enhance the bioelectrochemical transfer of electrons from the microorganism to the transducer. This latter part of this chapter investigates the ability of ferricyanide, toluidine blue, uniblue and two anthraquinones to mediate the microorganism-electrode interaction. Toluidine blue was the only mediator tested where significant changes upon the addition of Listeria were observed. These changes were not proportional to concentration, making this technique non-ideal. In Chapter 5, a successful approach to the mediation of the bioelectrochemical process is described. This research has shown a water-soluble conducting polymer (polymethoxyaniline sulfonate (PMAS)) to be successful in mediating the electron transfer from a microorganism (Listeria monocytogenes) to a glassy carbon substrate. Graphical representation of the change in current, at a potential of +0.8V, observed after the addition of the Listeria, showed a linear relationship between peak current and microorganism concentration. The detection limit of this technique has been determined to be between lOmo/ml and lOOmo/ml and a detection time in the order of a few minutes (\u3c15mins). The changes recorded in the electrochemistry can also be observed using UV-vis spectroscopy. Addition of the microorganism to the parent polymer results in changes absorbance being observed. Fractionating the polymer into eight separate molecular weight fractions between 1700 and 21000amu gave spectra with different absorbance values resulting from the addition of the Listeria to each individual fraction. The uniqueness of the PMAS response has been confirmed by studies using another water-soluble conducting polymer, poly-pyrrole butane sulfonate. This water soluble polypyrrole showed no responses to the addition of the microorganisms using either electrochemistry or spectroscopy. It is suggested that the high sensitivity of this technique can be attributed to the unique nature of the PMAS. It is the interaction the microorganism and the conveyance of the electron processes along the polymer backbone that allows small viable numbers to be reproducibly detected

Carbon nanotube architectures as catalyst supports for proton exchange membrane fuel cells

Catalyst support materials exhibit great influence on the performance and durability of proton exchange membrane (PEM) fuel cells. This minireview article summarises recent developments into carbon nanotube-based support materials for PEM fuel cells, including the membrane electrode assembly (MEA). The advantages of using CNTs to promote catalyst performance and stability, a perspective on research directions and strategies to improve fuel cell performance and durability are discussed. It is hoped that this mini-review will act as a conduit for future developments in catalyst supports and MEA design for PEM fuel cells