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  • Journal article
    Dewage HH, Yufit V, Brandon NP, 2015,

    Study of Loss Mechanisms Using Half-Cell Measurements in a Regenerative Hydrogen Vanadium Fuel Cell

    , Journal of the Electrochemical Society, Vol: 163, Pages: A5236-A5243, ISSN: 0013-4651

    The positioning of reference electrodes in redox flow batteries without disturbing the cell operation represents a great challenge. However decoupling anode and cathode processes is crucial in order to fully understand the losses in the system so it can be further optimized. The feasibility of a regenerative fuel cell based on an V(IV)/V(V) electrolyte and hydrogen gas has previously been demonstrated. In this investigation, using electrochemical impedance spectroscopy, the various losses of the cathode, anode and whole cell were established using an alternative reference electrode set-up. The findings showed that the largest irreversible losses under the conditions tested arose from diffusion limitations in the cathode and the effect of vanadium crossover and therefore adsorption onto the platinum layer of the hydrogen electrode leading to higher losses on the anode. These results highlight the potential for further improvement and optimization of cell design and materials for both electrodes in the Regenerative Hydrogen Vanadium Fuel Cell.

  • Journal article
    Holland RA, Scott KA, Florke M, Brown G, Ewers RM, Famer E, Kapos V, Muggeridge AH, Scharlemann JPW, Taylor G, Barrett J, Eigenbrod Fet al., 2015,

    Global impacts of energy demand on the freshwater resources of nations

    , Proceedings of the National Academy of Sciences of the United States of America, Vol: 112, Pages: E6707-E6716, ISSN: 0027-8424

    The growing geographic disconnect between consumption of goods, the extraction and processing of resources, and the environmental impacts associated with production activities makes it crucial to factor global trade into sustainability assessments. Using an empirically validated environmentally extended global trade model we examine the relationship between two key resources underpinning economies and human well-being - energy and freshwater. A comparison of three energy sectors (petroleum, gas, electricity) reveals that freshwater consumption associated with gas and electricity production is largely confined within the territorial boundaries where demand originates. This contrasts with petroleum, which exhibits a varying ratio of territorial to international freshwater consumption depending on the origin of demand. For example, while the USA and China have similar demand associated with the petroleum sector, international freshwater consumption is three times higher for the former than the latter. Based on mapping patterns of freshwater consumption associated with energy sectors at subnational scales, our analysis also reveals concordance between pressure on freshwater resources associated with energy production and freshwater scarcity in a number of river basins globally. These energy-driven pressures on freshwater resources in areas distant from the origin of energy demand complicate the design of policy to ensure security of fresh water and energy supply. While much of the debate around energy is focussed on greenhouse gas emissions, our findings highlight the need to consider the full range of consequences of energy production when designing policy.

  • Journal article
    Morel CRG, van Reeuwijk M, Graf T, 2015,

    Systematic investigation of non-Boussinesq effects in variable-density groundwater flow simulations

    , JOURNAL OF CONTAMINANT HYDROLOGY, Vol: 183, Pages: 82-98, ISSN: 0169-7722
  • Journal article
    Collier JS, Oggioni F, Gupta S, Garcia-Moreno D, Trentesaux A, De Batist Met al., 2015,

    Streamlined islands and the English Channel megaflood hypothesis

    , Global and Planetary Change, Vol: 135, Pages: 190-206, ISSN: 0921-8181

    Recognising ice-age catastrophic megafloods is important because they had significant impact on large-scale drainage evolution and patterns of water and sediment movement to the oceans, and likely induced very rapid, short-term effects on climate. It has been previously proposed that a drainage system on the floor of the English Channel was initiated by catastrophic flooding in the Pleistocene but this suggestion has remained controversial. Here we examine this hypothesis through an analysis of key landform features. We use a new compilation of multi- and single-beam bathymetry together with sub-bottom profiler data to establish the internal structure, planform geometry and hence origin of a set of 36 mid-channel islands. Whilst there is evidence of modern-day surficial sediment processes, the majority of the islands can be clearly demonstrated to be formed of bedrock, and are hence erosional remnants rather than depositional features. The islands display classic lemniscate or tear-drop outlines, with elongated tips pointing downstream, typical of streamlined islands formed during high-magnitude water flow. The length-to-width ratio for the entire island population is 3.4 ± 1.3 and the degree-of-elongation or k-value is 3.7 ± 1.4. These values are comparable to streamlined islands in other proven Pleistocene catastrophic flood terrains and are distinctly different to values found in modern-day rivers. The island geometries show a correlation with bedrock type: with those carved from Upper Cretaceous chalk having larger length-to-width ratios (3.2 ± 1.3) than those carved into more mixed Paleogene terrigenous sandstones, siltstones and mudstones (3.0 ± 1.5). We attribute these differences to the former rock unit having a lower skin friction which allowed longer island growth to achieve minimum drag. The Paleogene islands, although less numerous than the Chalk islands, also assume more perfect lemniscate shapes. These lithologies therefore

  • Journal article
    Woodward G, Bonada N, Feeley HB, Giller PSet al., 2015,

    Resilience of a stream community to extreme climatic events and long-term recovery from a catastrophic flood

    , FRESHWATER BIOLOGY, Vol: 60, Pages: 2497-2510, ISSN: 0046-5070
  • Journal article
    Chu W, Yao D, Gao N, Bond T, Templeton MRet al., 2015,

    The enhanced removal of carbonaceous and nitrogenous disinfection by-product precursors using integrated permanganate oxidation and powdered activated carbon adsorption pretreatment

    , Chemosphere, Vol: 141, Pages: 1-6, ISSN: 0045-6535
  • Journal article
    Hynson NA, Bidartondo MI, Read DJ, 2015,

    Are there geographic mosaics of mycorrhizal specificity and partial mycoheterotrophy? A case study in Moneses uniflora (Ericaceae).

    , New Phytol, Vol: 208, Pages: 1003-1007
  • Journal article
    Cicciotti M, Xenos DP, Bouaswaig AEF, Thornhill NF, Martinez-Botas RFet al., 2015,

    Physical modelling of industrial multistage centrifugal compressors for monitoring and simulation

    , PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE, Vol: 229, Pages: 3433-3448, ISSN: 0954-4062
  • Report
    Hanna R, Gross R, Speirs J, Heptonstall PJ, Gambhir Aet al., 2015,

    Innovation timelines from invention to maturity: A rapid review of the evidence on the time taken for new technologies to reach widespread commercialisation

  • Journal article
    Samsatli S, Staffell I, Samsatli NJ, 2015,

    Optimal design and operation of integrated wind-hydrogen-electricity networks for decarbonising the domestic transport sector in Great Britain

    , International Journal of Hydrogen Energy, Vol: 41, Pages: 447-475, ISSN: 1879-3487

    This paper presents the optimal design and operation of integrated wind-hydrogen-electricity networks using the general mixed integer linear programming energy network model, STeMES (Samsatli and Samsatli, 2015). The network comprises: wind turbines; electrolysers, fuel cells, compressors and expanders; pressurised vessels and underground storage for hydrogen storage; hydrogen pipelines and electricity overhead/underground transmission lines; and fuelling stations and distribution pipelines.The spatial distribution and temporal variability of energy demands and wind availability were considered in detail in the model. The suitable sites for wind turbines were identified using GIS, by applying a total of 10 technical and environmental constraints (buffer distances from urban areas, rivers, roads, airports, woodland and so on), and used to determine the maximum number of new wind turbines that can be installed in each zone.The objective is the minimisation of the total cost of the network, subject to satisfying all of the demands of the domestic transport sector in Great Britain. The model simultaneously determines the optimal number, size and location of each technology, whether to transmit the energy as electricity or hydrogen, the structure of the transmission network, the hourly operation of each technology and so on. The cost of distribution was estimated from the number of fuelling stations and length of the distribution pipelines, which were determined from the demand density at the 1 km level.Results indicate that all of Britain's domestic transport demand can be met by on-shore wind through appropriately designed and operated hydrogen-electricity networks. Within the set of technologies considered, the optimal solution is: to build a hydrogen pipeline network in the south of England and Wales; to supply the Midlands and Greater London with hydrogen from the pipeline network alone; to use Humbly Grove underground storage for seasonal storage and pressurised ve

  • Journal article
    Yang M, Martinez-Botas R, Rajoo S, Yokoyama T, Ibaraki Set al., 2015,

    An investigation of volute cross-sectional shape on turbocharger turbine under pulsating conditions in internal combustion engine

    , Energy Conversion and Management, Vol: 105, Pages: 167-177, ISSN: 0196-8904

    Engine downsizing is a proven method for CO2 reduction in Internal Combustion Engine (ICE). A turbocharger, which reclaims the energy from the exhaust gas to boost the intake air, can effectively improve the power density of the engine thus is one of the key enablers to achieve the engine downsizing. Acknowledging its importance, many research efforts have gone into improving a turbocharger performance, which includes turbine volute. The cross-section design of a turbine volute in a turbocharger is usually a compromise between the engine level packaging and desired performance. Thus, it is beneficial to evaluate the effects of cross-sectional shape on a turbine performance. This paper presents experimental and computational investigation of the influence of volute cross-sectional shape on the performance of a radial turbocharger turbine under pulsating conditions. The cross-sectional shape of the baseline volute (denoted as Volute B) was optimized (Volute A) while the annulus distribution of area-to-radius ratio (A/R) for the two volute configurations are kept the same. Experimental results show that the turbine with the optimized volute A has better cycle averaged efficiency under pulsating flow conditions, for different loadings and frequencies. The advantage of performance is influenced by the operational conditions. After the experiment, a validated unsteady computational fluid dynamics (CFD) modeling was employed to investigate the mechanism by which performance differs between the baseline volute and the optimized version. Computational results show a stronger flow distortion in spanwise direction at the rotor inlet with the baseline volute. Furthermore, compared with the optimized volute, the flow distortion is more sensitive to the pulsating flow conditions in the baseline volute. This is due to the different secondary flow pattern in the cross-sections, hence demonstrating a direction for desired volute cross-sectional shape to be used in a turbocharger rad

  • Journal article
    Bond T, Templeton MR, Mokhtar Kamal NH, Graham NJD, Kanda Ret al., 2015,

    Nitrogenous disinfection byproducts in English drinking water supply systems: occurrence, bromine substitution and correlation analysis

    , Water Research, Vol: 85, Pages: 85-94, ISSN: 0043-1354

    Despite the recent focus on nitrogenous disinfection byproducts in drinking water, there is limited occurrence data available for many species. This paper analyses the occurrence of seven haloacetonitriles, three haloacetamides, eight halonitromethanes and cyanogen chloride in 20 English drinking water supply systems. It is the first survey of its type to compare bromine substitution factors (BSFs) between the haloacetamides and haloacetonitriles. Concentrations of the dihalogenated haloacetonitriles and haloacetamides were well correlated. Although median concentrations of these two groups were lower in chloraminated than chlorinated surface waters, median BSFs for both in chloraminated samples were approximately double those in chlorinated samples, which is significant because of the higher reported toxicity of the brominated species. Furthermore, median BSFs were moderately higher for the dihalogenated haloacetamides than for the haloacetonitriles. This indicates that, while the dihalogenated haloacetamides were primarily generated from hydrolysis of the corresponding haloacetonitriles, secondary formation pathways also contributed. Median halonitromethane concentrations were remarkably unchanging for the different types of disinfectants and source waters: 0.1 μg·mgTOC−1 in all cases. Cyanogen chloride only occurred in a limited number of samples, yet when present its concentrations were higher than the other N-DBPs. Concentrations of cyanogen chloride and the sum of the halonitromethanes were not correlated with any other DBPs.

  • Journal article
    Dons E, Goetschi T, Nieuwenhuijsen M, de Nazelle A, Anaya E, Avila-Palencia I, Brand C, Cole-Hunter T, Gaupp-Berghausen M, Kahlmeier S, Laeremans M, Mueller N, Orjuela JP, Raser E, Rojas-Rueda D, Standaert A, Stigell E, Uhlmann T, Gerike R, Panis LIet al., 2015,

    Physical activity through sustainable transport approaches (PASTA): protocol for a multi-centre, longitudinal study

    , BMC Public Health, Vol: 15, ISSN: 1471-2458

    BackgroundPhysical inactivity is one of the leading risk factors for non-communicable diseases, yet many are not sufficiently active. The Physical Activity through Sustainable Transport Approaches (PASTA) study aims to better understand active mobility (walking and cycling for transport solely or in combination with public transport) as an innovative approach to integrate physical activity into individuals’ everyday lives. The PASTA study will collect data of multiple cities in a longitudinal cohort design to study correlates of active mobility, its effect on overall physical activity, crash risk and exposure to traffic-related air pollution.Methods/DesignA set of online questionnaires incorporating gold standard approaches from the physical activity and transport fields have been developed, piloted and are now being deployed in a longitudinal study in seven European cities (Antwerp, Barcelona, London, Oerebro, Rome, Vienna, Zurich). In total, 14000 adults are being recruited (2000 in each city). A first questionnaire collects baseline information; follow-up questionnaires sent every 13 days collect prospective data on travel behaviour, levels of physical activity and traffic safety incidents. Self-reported data will be validated with objective data in subsamples using conventional and novel methods. Accelerometers, GPS and tracking apps record routes and activity. Air pollution and physical activity are measured to study their combined effects on health biomarkers. Exposure-adjusted crash risks will be calculated for active modes, and crash location audits are performed to study the role of the built environment. Ethics committees in all seven cities have given independent approval for the study.DiscussionThe PASTA study collects a wealth of subjective and objective data on active mobility and physical activity. This will allow the investigation of numerous correlates of active mobility and physical activity using a data set that advances previous efforts in

  • Journal article
    Brown S, Mahgerefteh H, Martynov S, Sundara V, Mac Dowell Net al., 2015,

    A multi-source flow model for CCS pipeline transportation networks

    , International Journal of Greenhouse Gas Control, Vol: 43, Pages: 108-114, ISSN: 1750-5836

    As part of the operation of the carbon capture and storage process, there are clear practical and economic incentives in employing an integrated pipeline network system involving the capture of CO2 from multiple emission sources such as power plants or steel works followed by injection into a single storage site. This paper presents the development and testing of multi-source flow model for predicting the entire flow conditions such as pressure, temperature, fluid phase and CO2 composition throughout the pipeline network and the delivery to the storage site. The model also accounts for pipeline elevation and periodic variations in feed source flow rate, for example as a result of the ramping up or ramping down of power production from coal fired power stations connected to the pipeline network. The ability to produce the above information is of vital importance given the large impact of the stream impurities on the CO2 phase behaviour and their physiochemical interactions with the pipeline material of construction, compressor power requirements and the storage reservoir performance.

  • Journal article
    Kowal J, Pressel S, Duckett JG, Bidartondo MIet al., 2015,

    Liverworts to the rescue: an investigation of their efficacy as mycorrhizal inoculum for vascular plants

    , Functional Ecology, Vol: 30, Pages: 1014-1023, ISSN: 1365-2435

    1. Pezoloma ericae (D.J. Read) Baral, a widespread mycorrhizal fungus of plants in the Ericales,is known to form intracellular associations with several families of leafy liverworts(Schistochilaceae, Lepidoziaceae, Cephaloziaceae, Cephaloziellaceae) in vitro. The ecologicalsignificance of this link between vascular and non-vascular plants is unknown.2. Fungal symbionts were isolated from rhizoids of the leafy liverworts Cephalozia connivens(Dicks.) Lindb. and C. bicuspidata (L.) Dum. (Cephaloziaceae), as well as from the hair rootsof two dominant ericoid mycorrhiza-forming species of European heathlands, Erica tetralix(L.) and Calluna vulgaris (L.).3. Using pure cultures of P. ericae, we resynthesized liverwort–fungus associations to use colonizedliverworts as inoculum which was applied to substrates supporting the growth of heatherseedlings and cuttings. Effects were quantified using germination, rooting, plant colonization,plant survival under waterlogging stress and growth in height in experimental systems withand without liverworts and/or fungi.4. Fungal symbionts growing from liverwort rhizoids readily colonized the hair roots of ericaceousplants to form typical ericoid mycorrhizas.5. The presence of inoculum-bearing liverworts led to significant increases in plant growth.Erica tetralix was more responsive to inoculation than C. vulgaris.6. Ericaceous cuttings rooted and survived more successfully when they were coplanted withpreviously colonized liverwort stems.7. We demonstrate, under realistic ecological circumstances, that liverworts can deliver mycorrhizalinoculum and improve the establishment of vascular plants. We propose that by providingsources of mycorrhizal inoculum, symbiotic non-vascular plants can contribute to therestoration of plant communities dominated by Ericales plants. This research leads to broaderknowledge about the function of ericoid mycorrhizas in ecosystems.

  • Journal article
    Costall AW, Gonzalez Hernandez A, Newton PJ, Martinez-Botas RFet al., 2015,

    Design methodology for radial turbo expanders in mobile organic Rankine cycle applications

    , Applied Energy, Vol: 157, Pages: 729-743, ISSN: 0306-2619

    Future vehicles for clean transport will require new powertrain technologies to further reduce CO2 emissions. Mobile organic Rankine cycle systems target the recovery of waste heat in internal combustion engines, with the exhaust system identified as a prime source. This article presents a design methodology and working fluid selection for radial turbo expanders in a heavy-duty off-road diesel engine application. Siloxanes and Toluene are explored as the candidate working fluids, with the latter identified as the preferred option, before describing three radial turbine designs in detail. A small 15.5. kW turbine design leads to impractical blade geometry, but a medium 34.1. kW turbine, designed for minimum power, is predicted to achieve an isentropic efficiency of 51.5% at a rotational speed of 91.7. k. min-1. A similar 45.6. kW turbine designed for maximum efficiency yields 56.1% at 71.5. k. min-1. This emphasizes the main design trade-off - efficiency decreases and rotational speed increases as the power requirement falls - but shows reasonable radial turbine efficiencies and thus practical turbo expanders for mobile organic Rankine cycle applications are realizable, even considering the compromised flow geometry and high speeds imposed at such small scales.

  • Journal article
    Bushell S, Colley T, Workman M, 2015,

    A unified narrative for climate change

    , Nature Climate Change, Vol: 5, Pages: 971-973, ISSN: 1758-6798
  • Journal article
    Haghtalab S, Xanthopoulos P, Madani K, 2015,

    A robust unsupervised consensus control chart pattern recognition framework

    , EXPERT SYSTEMS WITH APPLICATIONS, Vol: 42, Pages: 6767-6776, ISSN: 0957-4174
  • Journal article
    Tsai M-Y, Hoek G, Eeftens M, de Hoogh K, Beelen R, Beregszaszi T, Cesaroni G, Cirach M, Cyrys J, De Nazelle A, de Vocht F, Ducret-Stich R, Eriksen K, Galassi C, Grazuleviciene R, Grazulevicius T, Grivas G, Gryparis A, Heinrich J, Hoffmann B, Iakovides M, Keuken M, Kraemer U, Kuenzli N, Lanki L, Madsen C, Meliefste K, Merritt A-S, Moelter A, Mosler G, Nieuwenhuijsen MJ, Pershagen G, Phuleria H, Quass U, Ranzi A, Schaffner E, Sokhi R, Stempfelet M, Stephanou E, Sugiri D, Taimisto P, Tewis M, Udvardy O, Wang M, Brunekreef Bet al., 2015,

    Spatial variation of PM elemental composition between and within 20 European study areas - Results of the ESCAPE project

    , ENVIRONMENT INTERNATIONAL, Vol: 84, Pages: 181-192, ISSN: 0160-4120
  • Journal article
    Vaissier V, Frost JM, Barnes PRF, Nelson Jet al., 2015,

    Influence of Intermolecular Interactions on the Reorganization Energy of Charge Transfer between Surface-Attached Dye Molecules

    , JOURNAL OF PHYSICAL CHEMISTRY C, Vol: 119, Pages: 24337-24341, ISSN: 1932-7447

    The parameters controlling the kinetics ofintermolecular charge transfer are traditionally estimatedfrom electronic structure calculations on the charge donorand charge acceptor in isolation. Here, we show that thisprocedure results in inaccuracies for hole transfer between apair of organic dye molecules by comparing charge-constraineddensity functional theory (DFT) calculations on a dyecation/neutral dye pair to the conventional DFT calculationson the isolated molecules. We quantify the error made in thereorganization energy of hole exchange between dye molecules(λi). We choose three indolene-based organic dyes with application to dye-sensitized solar cells, namely, D149, D102, and D131,for which experimental values of λ are available. We find that, although highly system dependent, the intermolecular interactionbetween the charge donor and acceptor can lead to a 0.25 eV change in λi, illustrating the limitations of the widely used originalmethod in predicting the rate of charge transfer.

  • Journal article
    Paul M, van de Flierdt T, Rehkamper M, Khondoker R, Weiss D, Lohan MC, Homoky WBet al., 2015,

    Tracing the Agulhas leakage with lead isotopes

    , Geophysical Research Letters, Vol: 20, Pages: 8515-8521, ISSN: 1944-8007

    The transport of warm and salty waters from the Indian Ocean to the South Atlantic by the Agulhas Current constitutes a key return route of the meridional overturning circulation. Despite, the importance of the Agulhas Leakage on interoceanic exchange, its role on biogeochemical cycles is poorly documented. Here, we present the first lead (Pb) concentration and isotope data for surface seawater collected during the GEOTRACES cruise D357 in the Agulhas current system. Lead in surface waters of the Cape Basin is described by three distinct endmembers: the South African coast, open South Atlantic seawater, and Indian Ocean seawater. The latter stands out in its Pb isotopic composition and can be tracked within two distinct Agulhas rings. High Pb concentrations in the Agulhas rings further corroborate an Indian Ocean provenance of waters, and suggests that the Agulhas Leakage not only represents a major conduit for heat, but also for trace metals.

  • Journal article
    Hausmann U, Czaja A, Marshall J, 2015,

    Estimates of air–sea feedbacks on sea surface temperature anomalies in the southern ocean

    , Journal of Climate, Vol: 29, Pages: 439-454, ISSN: 1520-0442

    Sea surface temperature (SST) air–sea feedback strengths and associated decay time scales in the Southern Ocean (SO) are estimated from observations and reanalysis datasets of SST, air–sea heat fluxes, and ocean mixed layer depths. The spatial, seasonal, and scale dependence of the air–sea heat flux feedbacks is mapped in circumpolar bands and implications for SST persistence times are explored. It is found that the damping effect of turbulent heat fluxes dominates over that due to radiative heat fluxes. The turbulent heat flux feedback acts to damp SSTs in all bands and spatial scales and in all seasons, at rates varying between 5 and 25 W m−2 K−1, while the radiative heat flux feedback has a more uniform spatial distribution with a magnitude rarely exceeding 5 W m−2 K−1. In particular, the implied net air–sea feedback (turbulent + radiative) on SST south of the polar front, and in the region of seasonal sea ice, is as weak as 5–10 W m−2 K−1 in the summertime on large spatial scales. Air–sea interaction alone thus allows SST signals induced around Antarctica in the summertime to persist for several seasons. The damping effect of mixed layer entrainment on SST anomalies averages to approximately 20 W m−2 K−1 across the ACC bands in the summer-to-winter entraining season and thereby reduces summertime SST persistence to less than half of that predicted by air–sea interaction alone (i.e., 3–6 months).

  • Journal article
    Brindley H, Osipov S, Bantges R, Smirnov A, Banks J, Levy R, Prakash PJ, Stenchikov Get al., 2015,

    An assessment of the quality of aerosol retrievals over the Red Sea and evaluation of the climatological cloud-free dust direct radiative effect in the region

    , Journal of Geophysical Research: Atmospheres, Vol: 120, ISSN: 2169-897X

    Ground-based and satellite observations are used in conjunction with the Rapid RadiativeTransfer Model (RRTM) to assess climatological aerosol loading and the associated cloud-free aerosol directradiative effect (DRE) over the Red Sea. Aerosol optical depth (AOD) retrievals from the Moderate ResolutionImaging Spectroradiometer and Spinning Enhanced Visible and InfraRed Imager (SEVIRI) instruments are firstevaluated via comparison with ship-based observations. Correlations are typically better than 0.9 with verysmall root-mean-square and bias differences. Calculations of the DRE along the ship cruises using RRTM alsoshow good agreement with colocated estimates from the Geostationary Earth Radiation Budget instrumentif the aerosol asymmetry parameter is adjusted to account for the presence of large particles. A monthlyclimatology of AOD over the Red Sea is then created from 5 years of SEVIRI retrievals. This shows enhancedaerosol loading and a distinct north to south gradient across the basin in the summer relative to the wintermonths. The climatology is used with RRTM to estimate the DRE at the top and bottom of the atmosphereand the atmospheric absorption due to dust aerosol. These climatological estimates indicate that althoughlongwave effects can reach tens of W m 2, shortwave cooling typically dominates the net radiativeeffect over the Sea, being particularly pronounced in the summer, reaching 120 W m 2 at the surface.The spatial gradient in summertime AOD is reflected in the radiative effect at the surface and in associateddifferential heating by aerosol within the atmosphere above the Sea. This asymmetric effect is expected toexert a significant influence on the regional atmospheric and oceanic circulation.

  • Journal article
    Brindley H, Osipov S, Bantges R, Smirnov A, Banks J, Levy R, Prakash PJ, Stenchikov Get al., 2015,

    An assessment of the quality of aerosol retrievals over the Red Sea and evaluation of the climatological cloud-free dust direct radiative effect in the region

    , Journal of Geophysical Research: Atmospheres, Vol: 120, Pages: 10862-10878, ISSN: 2169-897X

    Ground-based and satellite observations are used in conjunction with the Rapid Radiative Transfer Model (RRTM) to assess climatological aerosol loading and the associated cloud-free aerosol direct radiative effect (DRE) over the Red Sea. Aerosol optical depth (AOD) retrievals from the Moderate Resolution Imaging Spectroradiometer and Spinning Enhanced Visible and InfraRed Imager (SEVIRI) instruments are first evaluated via comparison with ship-based observations. Correlations are typically better than 0.9 with very small root-mean-square and bias differences. Calculations of the DRE along the ship cruises using RRTM also show good agreement with colocated estimates from the Geostationary Earth Radiation Budget instrument if the aerosol asymmetry parameter is adjusted to account for the presence of large particles. A monthly climatology of AOD over the Red Sea is then created from 5 years of SEVIRI retrievals. This shows enhanced aerosol loading and a distinct north to south gradient across the basin in the summer relative to the winter months. The climatology is used with RRTM to estimate the DRE at the top and bottom of the atmosphere and the atmospheric absorption due to dust aerosol. These climatological estimates indicate that although longwave effects can reach tens of W m−2, shortwave cooling typically dominates the net radiative effect over the Sea, being particularly pronounced in the summer, reaching 60 W m−2 at the surface. The spatial gradient in summertime AOD is reflected in the radiative effect at the surface and in associated differential heating by aerosol within the atmosphere above the Sea. This asymmetric effect is expected to exert a significant influence on the regional atmospheric and oceanic circulation.

  • Journal article
    Jimenez-Espejo FJ, Pardos-Gene M, Martinez-Ruiz F, Garcia-Alix A, van de Flierdt T, Toyofuku T, Bahr A, Kreissig Ket al., 2015,

    Geochemical evidence for intermediate water circulation in the westernmost Mediterranean over the last 20 kyr BP and its impact on the Mediterranean Outflow

    , Global and Planetary Change, Vol: 135, Pages: 38-46, ISSN: 1872-6364

    The Mediterranean Outflow (MOW) is generated by deep and intermediate waters from different basins in the Mediterranean Sea. Despite the number of studies on Mediterranean water masses, little work has been done on the source and properties of intermediate waters in the westernmost Mediterranean Sea and their links with MOW. Here we examine three marine sediment records spanning the last 20 kyr, located at key depths to trace intermediate waters along the Alboran Sea. We use a combination of redox-sensitive elements, which can serve as proxies to reconstruct variations in the water column oxygenation and the Nd isotopic composition of foraminiferal ferromanganese coatings, in order to reconstruct water mass provenance of Eastern/Western Mediterranean waters.As measured, εNd < − 9.2 and a low U/Th ratio during glacial periods can be attributed to the presence of Western Mediterranean Deep Water (WMDW) at the study sites. During deglaciation, higher Nd isotopic compositions and U/Th ratios point to an enhanced contribution of the modified Levantine Intermediate Water (LIW). The comparison between our data and other LIW and MOW records suggests that i) the lower branch of MOW is linked to WMDW during the glacial period, ii) the middle MOW branch follows LIW activity during deglaciation, while iii) the upper branch is more active during late Holocene, coinciding with LIW formation increase after sapropel deposits. This reconstruction has significant implications for an understanding of the MOW evolution.

  • Journal article
    Zhou S-X, Medlyn BE, Prentice IC, 2015,

    Long-term water stress leads to acclimation of drought sensitivity of photosynthetic capacity in xeric but not riparian Eucalyptus species

    , Annals of Botany, Vol: 117, Pages: 133-144, ISSN: 1095-8290

    Background and Aims Experimental drought is well documented to induce a decline in photosynthetic capacity. However, if given time to acclimate to low water availability, the photosynthetic responses of plants to low soil moisture content may differ from those found in short-term experiments. This study aims to test whether plants acclimate to long-term water stress by modifying the functional relationships between photosynthetic traits and water stress, and whether species of contrasting habitat differ in their degree of acclimation.Methods Three Eucalyptus taxa from xeric and riparian habitats were compared with regard to their gas exchange responses under short- and long-term drought. Photosynthetic parameters were measured after 2 and 4 months of watering treatments, namely field capacity or partial drought. At 4 months, all plants were watered to field capacity, then watering was stopped. Further measurements were made during the subsequent ‘drying-down’, continuing until stomata were closed.Key Results Two months of partial drought consistently reduced assimilation rate, stomatal sensitivity parameters (g1), apparent maximum Rubisco activity (V′cmaxVcmax′) and maximum electron transport rate (J′maxJmax′). Eucalyptus occidentalis from the xeric habitat showed the smallest decline in V′cmaxVcmax′ and J′maxJmax′; however, after 4 months, V′cmaxVcmax′ and J′maxJmax′ had recovered. Species differed in their degree of V′cmaxVcmax′ acclimation. Eucalyptus occidentalis showed significant acclimation of the pre-dawn leaf water potential at which the V′cmaxVcmax′ and ‘true’ Vcmax (accounting for mesophyll conductance) declined most steeply during drying-down.Conclusions The findings indicate carbon loss under prolonged drought could be over-estimated without accounting for acclimation. In particular, (1) species from contrasting habitats differed in th

  • Journal article
    Ferrandiz V, Sarabia LA, Ortiz MC, Cheeseman CR, Garcia-Alcocel Eet al., 2015,

    Design of bespoke lightweight cement mortars containing waste expanded polystyrene by experimental statistical methods

    , Materials & Design, Vol: 89, Pages: 901-912, ISSN: 0261-3069

    This work assesses the reuse of waste expanded polystyrene (EPS) to obtain lightweight cement mortars. The factors and interactions which affect the properties of these mortars were studied by ad-hoc designs based on the d-optimal criterion. This method allow multiple factors to be modified simultaneously, which reduces the number of experiments compared with classical design. Four factors were studied at several levels: EPS type (two levels), EPS content (two levels), admixtures mix (three levels) and cement type (three levels). Two types of aggregate were also studied. The workability, air content, compressive strength, adhesive strength, bulk density and capillary absorption were experimentally tested. The effect of factors and interactions on the properties was modelled and analysed. The results demonstrate how the factors and synergistic interactions can be manipulated to manufacture lightweight mortars which satisfy the relevant EU standards. These mortars contain up to 60% of waste EPS, low amounts of admixtures and low clinker content CEM III. Sustainable mortars containing silica sand gave flow table spread values between 168 and 180 ± 4 mm, bulk density between 1280and 1110 ± 100 kg/m³, and C90 between 0.279 and 0.025 ± 0.07 kg/m²·min⁰′⁵, making them suitable for masonry, plastering and rendering applications.1

  • Journal article
    Cole-Hunter T, Weichenthal S, Kubesch N, Foraster M, Carrasco-Turigas G, Bouso L, Martinez D, Westerdahl D, de Nazelle A, Nieuwenhuijsen Met al., 2015,

    Impact of traffic-related air pollution on acute changes in cardiac autonomic modulation during rest and physical activity: a cross-over study

    , Journal of Exposure Science and Environmental Epidemiology, Vol: 26, Pages: 133-140, ISSN: 1559-0631

    People are often exposed to traffic-related air pollution (TRAP) during physical activity (PA), but it is not clear if PA modifies the impact of TRAP on cardiac autonomic modulation. We conducted a panel study among 28 healthy adults in Barcelona, Spain to examine how PA may modify the impact of TRAP on cardiac autonomic regulation. Participants completed four 2-h exposure scenarios that included either rest or intermittent exercise in high- and low-traffic environments. Time- and frequency-domain measures of heart rate variability (HRV) were monitored during each exposure period along with continuous measures of TRAP. Linear mixed-effects models were used to estimate the impact of TRAP on HRV as well as potential effect modification by PA. Exposure to TRAP was associated with consistent decreases in HRV; however, exposure–response relationships were not always linear over the broad range of exposures. For example, each 10 μg/m3 increase in black carbon was associated with a 23% (95% CI: −31, −13) decrease in high frequency power at the low-traffic site, whereas no association was observed at the high-traffic site. PA modified the impact of TRAP on HRV at the high-traffic site and tended to weaken inverse associations with measures reflecting parasympathetic modulation (P≤0.001). Evidence of effect modification at the low-traffic site was less consistent. The strength and direction of the relationship between TRAP and HRV may vary across exposure gradients. PA may modify the impact of TRAP on HRV, particularly at higher concentrations.

  • Journal article
    Moia D, Leijtens T, Noel N, Snaith HJ, Nelson J, Barnes PRFet al., 2015,

    Dye Monolayers Used as the Hole Transporting Medium in Dye-Sensitized Solar Cells

    , ADVANCED MATERIALS, Vol: 27, Pages: 5889-5894, ISSN: 0935-9648
  • Conference paper
    Mawhood RK, Slade R, Shah N, 2015,

    Policy options to promote perennial energy crops: the limitations of the English Energy Crops Scheme and the role for agent-based modelling in policy design

    , Wellesbourne, UK, Association of Applied Biologists: Biomass and Energy Crops V, Publisher: Association of Applied Biologists, Pages: 143-153, ISSN: 0265-1491

    The UK government’s bioenergy strategy anticipates the cultivation of between 300,000 and 900,000 ha of energy crops by 2030. Yet policy incentives to promote uptake of perennial energy crops (PECs), notably the English Energy Crops Scheme (ECS), have had little impact. Less than 10,000 ha of PECs were being grown in 2013. To investigate the barriers to deployment a critical literature review and stakeholder interviews were conducted. These identified numerous substantial obstacles regarding PEC economics, alignment with existing institutions and factors affecting risk perception. Many of these are interdependent and involve a broad range of stakeholders. Agent-based modelling is proposed as an approach to explore the cumulative impacts of individual stakeholders’ behaviours under alternative policy and market conditions.

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