Publications by authors named "David Butterfield"

Under the EU Air Quality Directive (AQD) 2008/50/EC member states are required to undertake routine monitoring of PM composition at background stations. The AQD states for PM speciation this should include at least: nitrate , sulfate , chloride (Cl), ammonium (NH4), sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), elemental carbon (EC) and organic carbon (OC). Until 2017, it was the responsibility of each country to determine the methodology used to report the composition for the inorganic components of PM.

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Studying specific subpopulations of cancer-derived extracellular vesicles (EVs) could help reveal their role in cancer progression. In cancer, an increase in reactive oxygen species (ROS) happens which results in lipid peroxidation with a major product of 4-hydroxynonenal (HNE). Adduction by HNE causes alteration to the structure of proteins, leading to loss of function.

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The discharge of hydrothermal vents on the seafloor provides energy sources for dynamic and productive ecosystems, which are supported by chemosynthetic microbial populations. These populations use the energy gained by oxidizing the reduced chemicals contained within the vent fluids to fix carbon and support multiple trophic levels. Hydrothermal discharge is ephemeral and chemical composition of such fluids varies over space and time, which can result in geographically distinct microbial communities.

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A novel application of the Theil-Sen robust regression method for determining the temporal trends in the concentration of heavy metals in UK ambient air over the period 2005-2020 is presented and compared to other regression methods. We have demonstrated improvements over non-robust methods of regression, proving the ability to tease out trends that are small with respect to the variability of the concentration measurement. The method is used to identify, in general, large and significant trends in the concentrations of Ni, As, Pb and V over the period 2005-2020, either across the UK as a whole or at groupings of site classifications in the UK.

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One of the biggest planetary challenges is the accelerating loss of biodiversity threatening ecosystem functioning on a global scale. The WWF Living Planet Report (https://livingplanet.panda.

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Single-celled microbial eukaryotes inhabit deep-sea hydrothermal vent environments and play critical ecological roles in the vent-associated microbial food web. 18S rRNA amplicon sequencing of diffuse venting fluids from four geographically- and geochemically-distinct hydrothermal vent fields was applied to investigate community diversity patterns among protistan assemblages. The four vent fields include Axial Seamount at the Juan de Fuca Ridge, Sea Cliff and Apollo at the Gorda Ridge, all in the NE Pacific Ocean, and Piccard and Von Damm at the Mid-Cayman Rise in the Caribbean Sea.

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Measurement of the composition of ambient air has become increasingly widespread over the last 50 years as the detrimental health effects of some air pollutants have become clearer and requirements for these measurements has been embedded in national and international legislation. The aim of this has been not only to assess exposure of the general population to air pollutants but also to assess the effectiveness of abatement strategies to reduce emissions of these pollutants at source. With a rich industrial heritage, the Swansea Valley (South Wales, UK) has long been associated with the refining and production of metal products, especially nickel.

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Alkaline fluids venting from chimneys of the Lost City hydrothermal field flow from a potentially vast microbial habitat within the seafloor where energy and organic molecules are released by chemical reactions within rocks uplifted from Earth's mantle. In this study, we investigated hydrothermal fluids venting from Lost City chimneys as windows into subseafloor environments where the products of geochemical reactions, such as molecular hydrogen (H), formate, and methane, may be the only available sources of energy for biological activity. Our deep sequencing of metagenomes and metatranscriptomes from these hydrothermal fluids revealed a few key species of archaea and bacteria that are likely to play critical roles in the subseafloor microbial ecosystem.

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Brain metabolism is comprised in Alzheimer's disease (AD) and Parkinson's disease (PD). Since the brain primarily relies on metabolism of glucose, ketone bodies, and amino acids, aspects of these metabolic processes in these disorders-and particularly how these altered metabolic processes are related to oxidative and/or nitrosative stress and the resulting damaged targets-are reviewed in this paper. Greater understanding of the decreased functions in brain metabolism in AD and PD is posited to lead to potentially important therapeutic strategies to address both of these disorders, which cause relatively long-lasting decreased quality of life in patients.

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Determining the concentration of carbonaceous particles in ambient air is important for climate modelling, source attribution and air quality management. This study presents the difficulties associated with the interpretation of apparent long-term changes in the mass absorption cross section (MAC) of carbonaceous particles in London and south-east England based on equivalent black carbon (eBC) and elemental carbon (EC) measurements between 2014 and 2019. Although these two measurement techniques were used to determine the concentration of carbonaceous aerosols, the concentrations of eBC and EC changed at different rates at all sites, and exhibited different long-term trends.

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Depressurization and sample processing delays may impact the outcome of shipboard microbial incubations of samples collected from the deep sea. To address this knowledge gap, we developed a remotely operated vehicle (ROV)-powered incubator instrument to carry out and compare results from and shipboard RNA stable isotope probing (RNA-SIP) experiments to identify the key chemolithoautotrophic microbes and metabolisms in diffuse, low-temperature venting fluids from Axial Seamount. All the incubations showed microbial uptake of labeled bicarbonate primarily by thermophilic autotrophic that oxidized hydrogen coupled with nitrate reduction.

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Pumped sorbent tube sampling is a well established method for the sampling of volatile organic compounds (VOCs) and semi volatile organic compounds (SVOCs) in ambient, indoor and workplace atmospheres. Safe sampling volumes and breakthrough volumes have been published for commonly found VOCs on widely used sorbents such as Tenax, however for newer sorbents and less commonly found VOCs there is less robust data. The Safe Sampling Volumes (SSVs) were determined from 15 tests of Retention Volume on 12 VOCs across the 3 sorbents.

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create extensive iron (Fe) oxide mats at marine hydrothermal vents, making them an ideal model for microbial Fe oxidation at circumneutral pH. Comparison of neutrophilic Fe oxidizer isolate genomes has revealed a hypothetical Fe oxidation pathway, featuring a homolog of the Fe oxidase Cyc2 from However, Cyc2 function is not well verified in neutrophilic Fe oxidizers, particularly in Fe-oxidizing environments. Toward this, we analyzed genomes and metatranscriptomes of , using 53 new high-quality metagenome-assembled genomes reconstructed from Fe mats at Mid-Atlantic Ridge, Mariana Backarc, and Loihi Seamount (Hawaii) hydrothermal vents.

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Current methods for biochemical and biogeochemical analysis of the deep-sea hydrothermal vent ecosystems rely on water sample recovery, or in situ analysis using underwater instruments with limited range of analyte detection and limited sensitivity. Even in cases where large quantities of sample are recovered, labile dissolved organic compounds may not be detected due to time delays between sampling and preservation. Here, we present a novel approach for in situ extraction of organic compounds from hydrothermal vent fluids through a unique solid phase microextraction (SPME) sampler.

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The monitoring of metals in ambient air has been undertaken for over 40 years on a national basis in the UK. During this period, the UK pollution landscape has continued to evolve in terms of emission sources, and the measurement framework for metals in ambient air, the UK Heavy Metals Monitoring Network, has also been subject to significant configuration changes. Therefore, this work provides a timely review of more recent concentration trends in the context of current emission profiles.

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There are many unknowns regarding the distribution, activity, community composition, and metabolic repertoire of microbial communities in the subseafloor of deep-sea hydrothermal vents. Here we provide the first characterization of subseafloor microbial communities from venting fluids along the central Mariana back-arc basin (15.5-18°N), where the slow-spreading rate, depth, and variable geochemistry along the back-arc distinguish it from other spreading centers.

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The size and biogeochemical impact of the subseafloor biosphere in oceanic crust remain largely unknown due to sampling limitations. We used reactive transport modeling to estimate the size of the subseafloor methanogen population, volume of crust occupied, fluid residence time, and nature of the subsurface mixing zone for two low-temperature hydrothermal vents at Axial Seamount. Monod CH production kinetics based on chemostat H availability and batch-culture Arrhenius growth kinetics for the hyperthermophile Methanocaldococcus jannaschii and thermophile Methanothermococcus thermolithotrophicus were used to develop and parameterize a reactive transport model, which was constrained by field measurements of H, CH, and metagenome methanogen concentration estimates in 20-40 °C hydrothermal fluids.

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At deep-sea hydrothermal vents, microbial communities thrive across geochemical gradients above, at, and below the seafloor. In this study, we determined the gene content and transcription patterns of microbial communities and specific populations to understand the taxonomy and metabolism both spatially and temporally across geochemically different diffuse fluid hydrothermal vents. Vent fluids were examined via metagenomic, metatranscriptomic, genomic binning, and geochemical analyses from Axial Seamount, an active submarine volcano on the Juan de Fuca Ridge in the NE Pacific Ocean, from 2013 to 2015 at three different vents: Anemone, Marker 33, and Marker 113.

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The Mariana region exhibits a rich array of hydrothermal venting conditions in a complex geological setting, which provides a natural laboratory to study the influence of local environmental conditions on microbial community structure as well as large-scale patterns in microbial biogeography. We used high-throughput amplicon sequencing of the bacterial small subunit (SSU) rRNA gene from 22 microbial mats collected from four hydrothermally active locations along the Mariana Arc and back-arc to explore the structure of lithotrophically-based microbial mat communities. The vent effluent was classified as iron- or sulfur-rich corresponding with two distinct community types, dominated by either Zetaproteobacteria or Epsilonproteobacteria, respectively.

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The European Committee for Standardisation (CEN) Technical Committee 264 'Air Quality' has recently produced a standard method for the measurements of organic carbon and elemental carbon in PM within its working group 35 in response to the requirements of European Directive 2008/50/EC. It is expected that this method will be used in future by all Member States making measurements of the carbonaceous content of PM. This paper details the results of a laboratory and field measurement campaign and the statistical analysis performed to validate the standard method, assess its uncertainty and define its working range to provide clarity and confidence in the underpinning science for future users of the method.

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The PI3K/mTOR signaling cascade is fundamental in T-cell activation and fate decisions. We showed the distinct regulation of PI3K/mTOR in regulatory and effector T-cells and proposed the potential therapeutic benefit of targeting this pathway to control the balance between effector and regulatory T-cell activities. Substantial adverse effects in long-term clinical usage of rapamycin suggest the use of alternative treatments in restraining effector T-cell function in transplant patients.

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Treatment of advanced hepatocellular carcinoma (HCC) remains a challenge due to the high tumor heterogeneity. In the present study, we aim to evaluate the impact of the β-catenin inhibitor, FH535, alone or in combination with the Ras/Raf/MAPK inhibitor Sorafenib, on the bioenergetics profiles of the HCC cell lines Huh7 and PLC/PRF/5. Single low-dose treatments with FH535 or Sorafenib promoted different effects on mitochondrial respiration and glycolysis in a cell type specific manner.

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European Committee for Standardisation (CEN) Technical Committee 264 'Air Quality' has recently produced a standard method for the measurements of anions and cations in PM within its Working Group 34 in response to the requirements of European Directive 2008/50/EC. It is expected that this method will be used in future by all Member States making measurements of the ionic content of PM. This paper details the results of a field measurement campaign and the statistical analysis performed to validate this method, assess its uncertainty and define its working range to provide clarity and confidence in the underpinning science for future users of the method.

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Thermophilic methanogens are common autotrophs at hydrothermal vents, but their growth constraints and dependence on H2 syntrophy in situ are poorly understood. Between 2012 and 2015, methanogens and H2-producing heterotrophs were detected by growth at 80°C and 55°C at most diffuse (7-40°C) hydrothermal vent sites at Axial Seamount. Microcosm incubations of diffuse hydrothermal fluids at 80°C and 55°C demonstrated that growth of thermophilic and hyperthermophilic methanogens is primarily limited by H2 availability.

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