Fate and influence of inorganics and heteroatoms during the hydrothermal carbonisation of biomass

Hydrothermal carbonisation (HTC) is an emerging biomass pre-treatment that works by converting biomass into a coal like material, in the process overcoming some of the inherent limitations of biomass. To date, there have been limited publications looking into the fate and influence inorganics and heteroatoms have on the HTC chemistry. This is surprising given these elements are of critical importance when it comes to the fuel’s utilisation. This work sets out to understand the role and fate of key inorganics and heteroatoms during HTC, but goes on to develop a mechanistic understanding of the HTC process chemistry. This work primarily focuses on the feedstocks Miscanthus, willow, brown kelp (macroalgae) and swine manure. Additionally, this work has also looked into the processing of food waste, secondary sewage sludge, AD press cake, microalgae, municipal solid wastes and oak wood, providing a large database of samples. Reaction parameters investigated as part of this work include how temperature, retention time, particle size, pH and recycling of process waters influence product yields, energy density, combustion properties, the bio-chemical composition of the bio-coal, the process water chemistry and the retention and removal of inorganics and heteroatoms. The results show that under the correct conditions HTC can produce a fuel with a HHV ranging from 25 to 30 MJ/kg (db) and the resulting bio-coal can burn like a coal, grind like coal and can overcome many of the limitations of burning biomass in pulverised coal plant. By recycling the process waters Miscanthus can be made into a fuel with an energy density of 29 MJ/kg (db), with an energy yield of 91 % and fuel properties comparable to a high volatile sub-bituminous coal. The behaviour of the inorganics and heteroatoms during HTC appear dependent on feedstock, the feedstocks inorganic chemistry and the HTC processing conditions. Generally speaking, alkali metals, which are primarily responsible for the slagging and fouling behaviour of solid fuels, are largely removed (>80%) during HTC. Moreover, when processing at 250 °C retention of calcium and reincorporation of phosphorus occurs. The combination of reduced alkali metals and relative increase in calcium and phosphorous in the ash brings about significant improvement in the fuels slagging and fouling propensity as demonstrated by the ash fusion test. It hypothesised that any residual potassium within the fuel should form calcium potassium phosphate complexes in the ash. These complexes are thermally stable and prevents the formation of low melting temperature potassium silicates or the volatilisation of potassium chloride, further reducing slagging, fouling and corrosion beyond that expected for alkali metal leaching. This can be applied to a range of low value fuels such as green harvested Miscanthus and seaweeds. This demonstrates the technologies potential to valorise low quality feedstock and produce a direct substitute bio-coal from an expanded range of terrestrial and aquatic biomass. Recycling process water brings about an increase in bio-coal energy density, energy yield and produces a fuel with more coal-like properties. It is hypothesised that the recycled process waters contain organic acids that hydrolyse the hemicellulose and cellulose to furfural like compounds at a lower temperature and increase saccharide concentrations within the process water at lower temperatures. The increased saccharide concentrations favour aromatization and repolymerisation, which better enables the decomposition products to undergo polymerisation and form the bio-coal before the increasing process temperature brings about their further degradation to organic acids. Once degraded to organic acids these acids appear to only undergo limited reincorporation into the bio-coal, but do appear to play a role in the demineralisation of the fuel. Based on this it is proposed that the slow heating rates followed by an hour retention time is favourable to overcome kinetic limitations otherwise imposed by faster heating rates and shorter retention times. The heteroatom oxygen plays a critical role in the reactions involved in HTC. The energy densification of the bio-coal is largely due to the deoxygenation of the fuel. Removal of this oxygen forms unsaturated compounds that polymerise quickly, and intermolecular dehydration results in polymerisation, condensation and aromatisation of these fragments. Oxygen is also critical in repolymerisation, with aromatic structures initially chemisorbed though reactive oxygen functionalities that dehydrate to form stable oxygen bonds linking a polymeric matrix of cyclic aromatic carbon rings. The retention of calcium also suggests it may play catalytic role in the repolymerisation process with the literature supporting this. There is however evidence that at high calcium concentrations, calcium in the process water can have an adverse effect on carbonisation, binding to surface oxygen functional groups on the biomass feedstock and preventing hydrolysis and decomposition of the feedstock

The potential for production of high quality bio-coal from early harvested Miscanthus by hydrothermal carbonisation

To meet combustion quality requirements, Miscanthus is conventionally harvested in late winter/early spring after senescence due to a lowering of fuel nitrogen, chlorine and ash content. This can overcome combustion issues such as slagging, fouling and corrosion however there is a significant reduction in dry matter yields compared to early harvesting in the autumn. In this study, Miscanthus × giganteus harvested conventionally (after senescence) and early (green) have been pre-treated by hydrothermal carbonisation (HTC) at 200 °C and 250 °C. HTC at 200 °C improves the grindability of the biomass but results in limited energy densification. HTC at 250 °C results in increased energy densification producing a bio-coal with a HHV ranging from 27 to 28 MJ/kg for early and 25 to 26 MJ/kg for conventional harvesting; the Hardgrove Grindability Index (HGI) increases from 0 to 150. At higher HTC temperatures, the combustion profile of the bio-coal exhibits a ‘coal like’ single stage combustion profile. HTC results in a significant reduction in alkali metal content, increases safe combustion temperatures and reduces the theoretical propensity of the derived fuel to slag, foul and corrode. The results indicate that HTC can valorise both conventional and early harvested Miscanthus without producing any adverse effect on the yields and quality of the bio-coal. The challenges associated with early harvesting of Miscanthus appear to be largely overcome by HTC resulting in increased yields of up to 40% per hectare due to reduction in dry matter loss

Brexit and the Cultural Sector

A collaborative ebook on the effects of the Brexit vote on the UK's cultural sector and its agents: "It's not just the economy, stupid! Brexit and the Cultural Sector", edited by Gesa Stedman and Sandra van Lente. Our contributors come from a broad range of cultural and artistic practice and many of them worry about two aspects which have come to the fore in the context of Brexit: the stark social rift which separates the Leave and Remain camps, and the nasty rise of xenophobia and insularity in all its different shapes and forms. Although our authors do not intend to be read or viewed as all-encompassing, and although they differ in respect to the focus they chose for their essays, poems, or statements, one aspect unifies their utterances: passion. Passion for the multi-faceted characteristics of culture, language, exchange, dialogue, border-crossings, passion for an outward-looking approach to both Britain, its different nations, and its neighbours close and far. A passionate fear of what Britain might lose in the process of departing from the EU. And the fear of loss does not concentrate on the loss of revenue or even on the probable obstacles to travel and artistic exchange once Brexit is in place. But the loss of ambivalence and ambiguity, the loss of conflicting opinions, texts, stances, diversity, in short: everything that culture, which is free to find its own forms of expression, is valued for

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

The Rapid ASKAP Continuum Survey III: Spectra and Polarisation In Cutouts of Extragalactic Sources (SPICE-RACS) first data release

The Australian SKA Pathfinder (ASKAP) radio telescope has carried out a survey of the entire Southern Sky at 887.5 MHz. The wide area, high angular resolution, and broad bandwidth provided by the low-band Rapid ASKAP Continuum Survey (RACS-low) allow the production of a next-generation rotation measure (RM) grid across the entire Southern Sky. Here we introduce this project as Spectral and Polarisation in Cutouts of Extragalactic sources from RACS (SPICE-RACS). In our first data release, we image 30 RACS-low fields in Stokes I, Q, U at 25" angular resolution, across 744-1032 MHz with 1 MHz spectral resolution. Using a bespoke, highly parallelised, software pipeline we are able to rapidly process wide-area spectro-polarimetric ASKAP observations. Notably, we use `postage stamp' cutouts to assess the polarisation properties of 105912 radio components detected in total intensity. We find that our Stokes Q and U images have an rms noise of ∼ 80 μJy PSF-1, and our correction for instrumental polarisation leakage allows us to characterise components with ≳ 1% polarisation fraction over most of the field of view. We produce a broadband polarised radio component catalogue that contains 5818 RM measurements over an area of ∼ 1300 deg2 with an average error in RM of 1.6+1.1-1.0 rad m-2, and an average linear polarisation fraction 3.4+3.0-1.6%. We determine this subset of components using the conditions that the polarised signal-to-noise ratio is > 8, the polarisation fraction is above our estimated polarised leakage, and the Stokes I spectrum has a reliable model. Our catalogue provides an areal density of 4±2 RMs deg-2; an increase of ∼ 4 times over the previous state-of-the-art (Taylor, Stil, Sunstrum 2009, ApJ, 702, 1230). Meaning that, having used just 3% of the RACS-low sky area, we have produced the 3rd largest RM catalogue to date. This catalogue has broad applications for studying astrophysical magnetic fields; notably revealing remarkable structure in the Galactic RM sky. We will explore this Galactic structure in a follow-up paper. We will also apply the techniques described here to produce an all-Southern-sky RM catalogue from RACS observations. Finally, we make our catalogue, spectra, images, and processing pipeline publicly available

The Science Performance of JWST as Characterized in Commissioning

This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies.Comment: 5th version as accepted to PASP; 31 pages, 18 figures; https://iopscience.iop.org/article/10.1088/1538-3873/acb29