Exploration for volcanogenic sulphide mineralisation at Benglog, north Wales

Exploration for volcanogenic sulphide mineralisation around Benglog is one of three investigations designed to assess the metallogenic potential of the Ordovician Aran Volcanic Group. Detailed geological mapping in the Benglog area enabled an interpretation of the volcanic environment, critical to such an assessment, to be made. The eruptive rocks are acid and basic in composition; the acid rocks are mostly ash-flow tuffs derived from outside the area, whereas the basic rocks have a local derivation. They are all interbedded with dark grey or black silty mudstone and were probably erupted in a submarine environment. Contemporaneous dolerite sills were intruded into wet sediment. This environment was suitable for volcanogenic exhalative sulphide deposits to form and indications of a metallogenic horizon were found at the top of the Y Fron Formation in the form of abundant pyrite, minor pyrrhotite and minor base metal enrichment. Soil samples, analysed for copper, lead and zinc, were collected and geophysical surveys were carried out along eleven east-west trending traverse lines 300 m apart across the volcanic succession. Indications were found of minor vein mineralisation at dolerite intrusion margins and locally along faults. Very high chargeability and low resistivity anomalies over mudstones did not spatially coincide with geochemical anomalies in soil, but the secondary redistribution of metals in soils and variable thickness of overburden precluded confident interpretation of the source of many soil anomalies. Geochemical drainage data, in conjunction with rock analyses, show strong barium enrichment in mudstones which could be volcanogenic in origin but related to two separate eruptive episodes. The findings of the survey were inconclusive. An environment suitable for the formation of volcanogenic exhalative sulphide deposits was established, but the geochemical and geophysical surveys located only minor vein mineralisation and tenuous indications of other styles of mineralisation. Recommendations are made for further work

Integrated CO2 capture and utilization using non-thermal plasmolysis

In this work, two simple processes for carbon dioxide (CO2) such as capture and utilization have been combined to form a whole systems approach to carbon capture and utilization (CCU). The first stage utilizes a pressure swing adsorption (PSA) system, which offers many benefits over current amine technologies. It was found that high selectivity can be achieved with rapid adsorption/desorption times while employing a cheap, durable sorbent that exhibits no sorbent losses and is easily regenerated by simple pressure drops. The PSA system is capable of capturing and upgrading the CO2 concentration of a waste gas stream from 12.5% to a range of higher purities. As many CCU end processes have some tolerance toward impurities in the feed, in the form of nitrogen (N2), for example, this is highly advantageous for this PSA system since CO2 purities in excess of 80% can be achieved with only a few steps and minimal energy input. Non-thermal plasma is one such technology that can tolerate, and even benefit from, small N2 impurities in the feed, therefore a 100% pure CO2 stream is not required. The second stage of this process deploys a nanosecond pulsed corona discharge reactor to split the captured CO2 into carbon monoxide (CO), which can then be used as a chemical feedstock for other syntheses. Corona discharge has proven industrial applications for gas cleaning and the benefit of pulsed power reduces the energy consumption of the system. The wire-in-cylinder geometry concentrates the volume of gas treated into the area of high electric field. Previous work has suggested that moderate conversions can be achieved (9%), compared to other non-thermal plasma methods, but with higher energy efficiencies (>60%)

Dependence of the Superconducting Transition Temperature of MgB2 on Pressure to 20 GPa

The dependence of Tc on nearly hydrostatic pressure has been measured for an isotopically pure (11B) MgB2 sample in a helium-loaded diamond-anvil-cell to nearly 20 GPa. Tc decreases monotonically with pressure from 39.1 K at ambient pressure to 20.9 K at 19.2 GPa. The initial dependence is the same as that obtained earlier (dTc/dP = -1.11(2) K/GPa) on the same sample in a He-gas apparatus to 0.7 GPa. The observed pressure dependence Tc(P) to 20 GPa can be readily described in terms of simple lattice stiffening within standard phonon-mediated BCS superconductivity.Comment: 9 pages, 3 figure

Searching for galaxy clusters in the VST-KiDS Survey

We present the methods and first results of the search for galaxy clusters in the Kilo Degree Survey (KiDS). The adopted algorithm and the criterium for selecting the member galaxies are illustrated. Here we report the preliminary results obtained over a small area (7 sq. degrees), and the comparison of our cluster candidates with those found in the RedMapper and SZ Planck catalogues; the analysis to a larger area (148 sq. degrees) is currently in progress. By the KiDS cluster search, we expect to increase the completeness of the clusters catalogue to z = 0.6-0.7 compared to RedMapper.Comment: 5 pages, 4 figures, to be published in the Proceedings of the Conference "The Universe of Digital Sky Surveys", Naples, November 25-28 201

Environmental baseline monitoring - Vale of Pickering: Phase I - final report (2015/16)

This report presents the collated results from the BGS-led project Science-based environmental baseline monitoring associated with shale gas development in the Vale of Pickering (including supplementary air quality monitoring in Lancashire). The project has been funded by a grant awarded by DECC for the period August 2015 – 31st March 2016. It complements (and extends to air quality) an on-going project, funded by BGS and the other project partners, in which similar activities are being carried out in the Fylde area of Lancashire. The project has initiated a wide-ranging environmental baseline monitoring programme that includes water quality (groundwater and surface water), seismicity, ground motion, atmospheric composition (greenhouse gases and air quality), soil gas and radon in air (indoors and outdoors). The motivation behind the project(s) was to establish independent monitoring in the area around the proposed shale gas hydraulic fracturing sites in the Vale of Pickering, North Yorkshire (Third Energy) and in Lancashire (Cuadrilla) before any shale gas operations take place. As part of the project, instrumentation has been deployed to measure, in real-time or near real-time, a range of environmental variables (water quality, seismicity, atmospheric composition). These data are being displayed on the project’s web site (www.bgs.ac.uk/Valeofpickering). Additional survey, sampling and monitoring has also been carried out through a co-ordinated programme of fieldwork and laboratory analysis, which has included installation of new monitoring infrastructure, to allow compilation of one of the most comprehensive environmental datasets in the UK. It is generally recognised that at least 12 months of baseline data are required. The duration of the grant award (7 months) has meant that this has not yet been possible. However there are already some very important findings emerging from the limited datasets which need be taken in to account when developing future monitoring strategy, policy and regulation. The information is not only relevant to the Vale of Pickering and Lancashire but will be more widely applicable in the UK and internationally. Although shale gas operations in other parts of the world are well-established there is a paucity of good baseline data and effective guidance on monitoring. It is hoped that the monitoring project will continue to allow at least 12 months of data for each of the work packages to be compiled and analysed. It will also allow the experience gained and the scientifically-robust findings to be used to develop and establish effective environmental monitoring strategies for shale gas and similar industrial activities

Non-perturbative effective field theory for two-leg antiferromagnetic spin ladders

We study the long wavelength limit of a spin 1/2 Heisenberg antiferromagnetic two-leg ladder, treating the interchain coupling in a non-perturbative way. We perform a mean field analysis and then include exactly the fluctuations. This allows for a discussion of the phase diagram of the system and provides an effective field theory for the low energy excitations. The coset fermionic Lagrangian obtained corresponds to a perturbed SU(4)_1/U(1) Conformal Field Theory (CFT). This effective theory is naturally embedded in a SU(2)_2 x Z_2 CFT, where perturbations are easily identified in terms of conformal operators in the two sectors. Crossed and zig-zag ladders are also discussed using the same approach.Comment: 14 pages LaTeX, 5 PostScript figures included using epsfig.sty; minor corrections and a few references adde

The fate of spinons in spontaneously dimerised spin-1/2 ladders

We study a weakly coupled, frustrated two-leg spin-1/2 Heisenberg ladder. For vanishing coupling between the chains, elementary excitations are deconfined, gapless spin-1/2 objects called spinons. We investigate the fate of spinons for the case of a weak interchain interaction. We show that despite a drastic change in ground state, which becomes spontaneously dimerised, spinons survive as elementary excitations but acquire a spectral gap. We furthermore determine the exact dynamical structure factor for several values of momentum transfer.Comment: 8 pages of revtex, 7 figures; discussion of physical picture for ground state and excitations in the "twistless" ladder expanded, version to appear in Phys Rev

Dynamics of ions in the selectivity filter of the KcsA channel

The statistical and dynamical properties of ions in the selectivity filter of the KcsA ion channel are considered on the basis of molecular dynamics (MD) simulations of the KcsA protein embedded in a lipid membrane surrounded by an ionic solution. A new approach to the derivation of a Brownian dynamics (BD) model of ion permeation through the filter is discussed, based on unbiased MD simulations. It is shown that depending on additional assumptions, ion’s dynamics can be described either by under-damped Langevin equation with constant damping and white noise or by Langevin equation with a fractional memory kernel. A comparison of the potential of the mean force derived from unbiased MD simulations with the potential produced by the umbrella sampling method demonstrates significant differences in these potentials. The origin of these differences is an open question that requires further clarifications