Electrochemical detection of chemical warfare agent simulants

This work attempted to detect chemical warfare agent (CWA) simulants via electrochemistry utilizing two approaches. The first approach consisted of a ferrocene (Fc) amino acid derivative film on Au surfaces. The molecule [(BocHN)Fc(CO)CSA]2 was electrodeposited onto Au microelectrodes through a S–Au bond. Once immobilized, the Fc amino acid derivative was Boc deprotected allowing for the amino group to react with the target molecule. Detection of the target simulant was monitored by cyclic voltammetry (CV) while following the formal potential of the Fc molecule, which is influenced by its immediate electronic microenvironment. Reaction with either 1 mM diethyl cyanophosphonate (DECP) or 2 chloroethyl ethyl sulfide (2 CEES), both effectively simulants for the CWAs Tabun nerve agent and blistering sulfur mustard respectively, was not observed. However, detection of 1 mM acetyl chloride was achieved by observing a potential anodic shift from 217 ± 6 mV, for the Boc deprotected form, to 388 ± 7 mV for the reacted state of the molecule. The lack of reactivity with the Fc amino acid system was hypothesized as a kinetic issue. In the second approach, the electrochemistry of gas generated naked Ag nanoparticles (NPs) deposited on indium tin oxide covered glass plates is compared to bulk polycrystalline Ag. The nano specific electrochemistry of Ag NPs has been identified and includes the preferential formation of â oxides. In 100 mM KOH supporting electrolyte, disruption of â oxide formation is exploited to test for the presence of 1 mM DECP resulting in the dissolution of Ag via cyanide complexes leading to a CV signal decrease. While in 8.0 M KOH, â oxide formation is enhanced leading to testing capabilities for 1 mM 2 CEES resulting in the disappearance of the â oxide peak and the appearance of surface oxide peak during CV. Analogous electrochemistry is not observed on polycrystalline bulk Ag

Dust mass concentrations from the UK volcanic ash lidar network compared with in-situ aircraft measurements

This is the final version. Available from EDP Sciences via the DOI in this record. The Met Office has recently established a series of 10 lidar / sun-photometer installations across the UK, consolidating their ash / aerosol remote sensing capabilities [1]. In addition to this network, the Met Office have acquired the Civil Contingency Aircraft (MOCCA) which allows airborne in-situ measurements of ash / aerosol scattering and size-distributions. Two case studies are presented in which mass concentrations of Saharan dust are obtained remotely using lidar returns, and are then compared with those obtained in-situ. A thorough analysis of the mass concentration uncertainty will be provided at the conference

Remote Sensing of Volcanic ASH at the Met Office

This is the final version. Available from EDP Sciences via the DOI in this record. The eruption of Eyjafjallajokull in 2010 has triggered the rapid development of volcanic ash remote sensing activities at the Met Office. Volcanic ash qualitative and quantitative mapping have been achieved using lidar on board the Facility for Airborne Atmospheric Measurements (FAAM) research aircraft, and using improved satellite retrieval algorithms. After the eruption, a new aircraft facility, the Met Office Civil Contingencies Aircraft (MOCCA), has been set up to enable a rapid response, and a network of ground-based remote sensing sites with lidars and sunphotometers is currently being developed. Thanks to these efforts, the United Kingdom (UK) will be much better equipped to deal with such a crisis, should it happen in the future.Met OfficeNER

Horizontal and vertical structure of the Eyjafjallajökull ash cloud over the UK: a comparison of airborne lidar observations and simulations

During April and May 2010 the ash cloud from the eruption of the Icelandic volcano Eyjafjallajökull caused widespread disruption to aviation over northern Europe. The location and impact of the eruption led to a wealth of observations of the ash cloud were being obtained which can be used to assess modelling of the long range transport of ash in the troposphere. The UK FAAM (Facility for Airborne Atmospheric Measurements) BAe-146-301 research aircraft overflew the ash cloud on a number of days during May. The aircraft carries a downward looking lidar which detected the ash layer through the backscatter of the laser light. In this study ash concentrations derived from the lidar are compared with simulations of the ash cloud made with NAME (Numerical Atmospheric-dispersion Modelling Environment), a general purpose atmospheric transport and dispersion model. The simulated ash clouds are compared to the lidar data to determine how well NAME simulates the horizontal and vertical structure of the ash clouds. Comparison between the ash concentrations derived from the lidar and those from NAME is used to define the fraction of ash emitted in the eruption that is transported over long distances compared to the total emission of tephra. In making these comparisons possible position errors in the simulated ash clouds are identified and accounted for. The ash layers seen by the lidar considered in this study were thin, with typical depths of 550–750 m. The vertical structure of the ash cloud simulated by NAME was generally consistent with the observed ash layers, although the layers in the simulated ash clouds that are identified with observed ash layers are about twice the depth of the observed layers. The structure of the simulated ash clouds were sensitive to the profile of ash emissions that was assumed. In terms of horizontal and vertical structure the best results were obtained by assuming that the emission occurred at the top of the eruption plume, consistent with the observed structure of eruption plumes. However, early in the period when the intensity of the eruption was low, assuming that the emission of ash was uniform with height gives better guidance on the horizontal and vertical structure of the ash cloud. Comparison of the lidar concentrations with those from NAME show that 2–5% of the total mass erupted by the volcano remained in the ash cloud over the United Kingdom

Evaluation of Fluorescent Confocal Microscopy for Intraoperative Analysis of Prostate Biopsy Cores

The use of fluorescent confocal microscopy allows fast and easy preparation of biopsy cores for intraoperative analysis. We observed strong concordance with traditional analysis in our study. The role of this technique is yet to be established

Biomass Burning Aerosols in the Amazon Basin, Characterised by Lidar, Optical Particle Counters, and Modelling

This is the final version. Available from EDP Sciences via the DOI in this record. This article has no abstract.Natural Environment Research Council (NERC)Met Offic

Volcanic ash layer depth: processes and mechanisms

The long duration of the 2010 Eyjafjallajökull eruption provided a unique opportunity to measure a widely dispersed volcanic ash cloud. Layers of volcanic ash were observed by the European Aerosol Research Lidar Network with a mean depth of 1.2 km and standard deviation of 0.9 km. In this paper we evaluate the ability of the Met Office's Numerical Atmospheric-dispersion Modelling Environment (NAME) to simulate the observed ash layers and examine the processes controlling their depth. NAME simulates distal ash layer depths exceptionally well with a mean depth of 1.2 km and standard deviation of 0.7 km. The dominant process determining the depth of ash layers over Europe is the balance between the vertical wind shear (which acts to reduce the depth of the ash layers) and vertical turbulent mixing (which acts to deepen the layers). Interestingly, differential sedimentation of ash particles and the volcano vertical emission profile play relatively minor roles

Saharan dust and biomass burning aerosols during ex-hurricane Ophelia: Observations from the new UK lidar and sun-photometer network

This is the final version. Available from European Geosciences Union (EGU) / Copernicus Publications via the DOI in this record. On 15-16 October 2017, ex-hurricane Ophelia passed to the west of the British Isles, bringing dust from the Sahara and smoke from Portuguese forest fires that was observable to the naked eye and reported in the UK's national press. We report here detailed observations of this event using the UK operational lidar and sun-photometer network, established for the early detection of aviation hazards, including volcanic ash. We also use ECMWF ERA5 wind field data and MODIS imagery to examine the aerosol transport. The observations, taken continuously over a period of 30 h, show a complex picture, dominated by several different aerosol layers at different times and clearly correlated with the passage of different air masses associated with the intense cyclonic system. A similar evolution was observed at several sites, with a time delay between them explained by their different location with respect to the storm and associated meteorological features. The event commenced with a shallow dust layer at 1-2 km in altitude and culminated in a deep and complex structure that lasted ∼12 h at each site over the UK, correlated with the storm's warm sector. For most of the time, the aerosol detected was dominated by mineral dust mixtures, as highlighted by depolarisation measurements, but an intense biomass burning aerosol (BBA) layer was observed towards the end of the event, lasting around 3 h at each site. The aerosol optical depth at 355 nm (AOD355) during the whole event ranged from 0.2 to 2.9, with the larger AOD correlated to the intense BBA layer. Such a large AOD is unprecedented in the UK according to AERONET records for the last 20 years. The Raman lidars permitted the measurement of the aerosol extinction coefficient at 355 nm, the particle linear depolarisation ratio (PLDR), and the lidar ratio (LR) and made the separation of the dust (depolarising) aerosol from other aerosol types possible. A specific extinction has also been computed to provide an estimate of the atmospheric concentration of both aerosol types separately, which peaked at 420±200 μgm-3 for the dust and 558±232 μgm-3 for the biomass burning aerosols. Back trajectories computed using the Numerical Atmospheric-dispersion Modelling Environment (NAME) were used to identify the sources and strengthen the conclusions drawn from the observations. The UK network represents a significant expansion of the observing capability in northern Europe, with instruments evenly distributed across Great Britain, from Camborne in Cornwall to Lerwick in the Shetland Islands, and this study represents the first attempt to demonstrate its capability and validate the methods in use. Its ultimate purpose will be the detection and quantification of volcanic plumes, but the present study clearly demonstrates the advanced capabilities of the network.Natural Environment Research CouncilUniversity of Exete