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Journal articleCulley DM, Funke SW, Kramer SC, et al., 2015,
Integration of cost modelling within the micro-siting design optimisation of tidal turbine arrays
, Renewable Energy, Vol: 85, Pages: 215-227, ISSN: 1879-0682The location of individual turbines within a tidal current turbine array – micro-siting – can have a significant impact on the power that the array may extract from the flow. Due to the infancy of the industry and the challenges of exploiting the resource, the economic costs of realising industrial scale tidal current energy projects are significant and should be considered as one of the key drivers of array design. This paper proposes a framework for the automated design of tidal current turbine arrays in which costs over the lifespan of the array may be modelled and considered as part of the design optimisation process. To demonstrate this approach, the cost of sub-sea cabling is incorporated by implementing a cable-routing algorithm alongside an existing gradient-based array optimisation algorithm. Three idealised test scenarios are used to demonstrate the effects of a financial-return optimising design approach as contrasted with a power maximisation approach.
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Journal articleGarzoli SL, Dong S, Fine R, et al., 2015,
The fate of the Deep Western Boundary Current in the South Atlantic
, Deep Sea Research Part I: Oceanographic Research Papers, Vol: 103, Pages: 125-136, ISSN: 0967-0637The pathways of recently ventilated North Atlantic Deep Water (NADW) are part of the lower limb of the Atlantic Meridional Overturning Circulation (AMOC). In the South Atlantic these pathways have been the subject of discussion for years, mostly due to the lack of observations. Knowledge of the pathways of the AMOC in the South Atlantic is a first order prerequisite for understanding the fluxes of climatically important properties. In this paper, historical and new observations, including hydrographic and oxygen sections, Argo data, and chlorofluorocarbons (CFCs), are examined together with two different analyzes of the Ocean general circulation model For the Earth Simulator (OFES) to trace the pathway of the recently ventilated NADW through the South Atlantic. CLIVAR-era CFCs, oxygen and salinity clearly show that the strongest NADW pathway in the South Atlantic is along the western boundary (similar to the North Atlantic). In addition to the western boundary pathway, tracers show an eastward spreading of NADW between ~17 and 25°S. Analyzed together with the results of earlier studies, the observations and model output presented here indicate that after crossing the equator, the Deep Western Boundary Current (DWBC) transports water with the characteristics of NADW and a total volume transport of approximately 14 Sv (1 Sv=106 m3 s−1). It crosses 5°S as a narrow western boundary current and becomes dominated by eddies further south. When this very energetic eddying flow reaches the Vitória-Trindade Ridge (~20°S), the flow follows two different pathways. The main portion of the NADW flow continues along the continental shelf of South America in the form of a strong reformed DWBC, while a smaller portion, about 22% of the initial transport, flows towards the interior of the basin.
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Journal articleMilner-Gulland EJ, Wallace A, Bunnefeld N, et al., 2015,
Quantifying the short-term costs of conservation interventions for fishers at Lake Alaotra, Madagascar
, PLOS One, Vol: 10, ISSN: 1932-6203Artisanal fisheries are a key source of food and income for millions of people, but if poorly managed, fishing can have declining returns as well as impacts on biodiversity. Management interventions such as spatial and temporal closures can improve fishery sustainability and reduce environmental degradation, but may carry substantial short-term costs for fishers. The Lake Alaotra wetland in Madagascar supports a commercially important artisanal fishery and provides habitat for a Critically Endangered primate and other endemic wildlife of conservation importance. Using detailed data from more than 1,600 fisher catches, we used linear mixed effects models to explore and quantify relationships between catch weight, effort, and spatial and temporal restrictions to identify drivers of fisher behaviour and quantify the potential effect of fishing restrictions on catch. We found that restricted area interventions and fishery closures would generate direct short-term costs through reduced catch and income, and these costs vary between groups of fishers using different gear. Our results show that conservation interventions can have uneven impacts on local people with different fishing strategies. This information can be used to formulate management strategies that minimise the adverse impacts of interventions, increase local support and compliance, and therefore maximise conservation effectiveness.
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Journal articleMilner-Gulland EJ, mcnamara J, rowcliffe M, et al., 2015,
Long-term spatio-temporal changes in a West African bushmeat trade system
, Conservation Biology, Vol: 29, Pages: 1446-1457, ISSN: 0888-8892Landscapes in many developing countries consist of a heterogeneous matrix of mixed agriculture and forest. Many of the generalist species in this matrix are increasingly traded in the bushmeat markets of West and Central Africa. However, to date there has been little quantification of how the spatial configuration of the landscape influences the urban bushmeat trade over time. As anthropogenic landscapes become the face of rural West Africa, understanding the dynamics of these systems has important implications for conservation and landscape management. The bushmeat production of an area is likely to be defined by landscape characteristics such as habitat disturbance, hunting pressure, level of protection, and distance to market. We explored (SSG, tense) the role of these four characteristics in the spatio-temporal dynamics of the commercial bushmeat trade around the city of Kumasi, Ghana, over 27 years (1978 to 2004). We used geographic information system methods to generate maps delineating the spatial characteristics of the landscapes. These data were combined with spatially explicit market data collected in the main fresh bushmeat market in Kumasi to explore the relationship between trade volume (measured in terms of number of carcasses) and landscape characteristics. Over time, rodents, specifically cane rats (Thryonomys swinderianus), became more abundant in the trade relative to ungulates and the catchment area of the bushmeat market expanded. Areas of intermediate disturbance supplied more bushmeat, but protected areas had no effect. Heavily hunted areas showed significant declines in bushmeat supply over time. Our results highlight the role that low intensity, heterogeneous agricultural landscapes can play in providing ecosystem services, such as bushmeat, and therefore the importance of incorporating bushmeat into ecosystem service mapping exercises. Our results also indicate that even where high bushmeat production is possible, current harvest levels may
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BookHaigh JD, Cargill P, 2015,
The Sun's Influence on Climate
, ISBN: 9780691153841"--Peter Pilewskie, University of Colorado Boulder "This succinct volume will be invaluable to scientists and general readers who want to learn more about the Sun and its effects on our climate system.
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Journal articleField KJ, Pressel S, Duckett JG, et al., 2015,
Symbiotic options for the conquest of land
, Trends in Ecology & Evolution, Vol: 30, Pages: 477-486, ISSN: 0169-5347The domination of the landmasses of Earth by plants starting during the Ordovician Period drastically altered the development of the biosphere and the composition of the atmosphere, with far-reaching consequences for all life ever since. It is widely thought that symbiotic soil fungi facilitated the colonization of the terrestrial environment by plants. However, recent discoveries in molecular ecology, physiology, cytology, and paleontology have brought into question the hitherto-assumed identity and biology of the fungi engaged in symbiosis with the earliest-diverging lineages of extant land plants. Here, we reconsider the existing paradigm and show that the symbiotic options available to the first plants emerging onto the land were more varied than previously thought.
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Journal articleThomas T, Mellor A, Hylton NP, et al., 2015,
Requirements for a GaAsBi 1 eV sub-cell in a GaAs-based multi-junction solar cell
, Semiconductor Science and Technology, Vol: 30, ISSN: 1361-6641 -
Conference paperAbolghasemi M, Piggott MD, Spinneken J, et al., 2015,
Simulating tidal turbines with mesh optimisation and RANS turbulence models
, 2015 European Wave and Tidal Energy Conference -
Book chapterHawkes A, Hanna R, 2015,
Market and policy influences
, Domestic Microgeneration Renewable and Distributed Energy Technologies, Policies and Economics, Publisher: Routledge, ISBN: 9781317448853Renewable and Distributed Energy Technologies, Policies and Economics Iain Staffell, Daniel J.L. Brett, Nigel P. Brandon, Adam D. Hawkes. [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] ...
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Journal articleNako AE, White AJ, Crimmin MR, 2015,
Bis(σ-B-H) complexes of copper(i): precursors to a heterogeneous amine-borane dehydrogenation catalyst
, Dalton Transactions, Vol: 44, Pages: 12530-12534, ISSN: 1477-9226A series of bis(σ-B-H) complexes of copper(i) have been prepared by displacement of arene solvent from a β-diketiminate copper(i) complex by four-coordinate boranes, H3B-L (L = NMe3, lutidine). In the presence of the same copper arene complex, the secondary amine-borane H3B-NMe2H undergoes dehydrogenation. We provide evidence for formation of a heterogengous catalyst from decomposition of the solution species.
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Journal articleBlamey J, Manovic V, Anthony EJ, et al., 2015,
On steam hydration of CaO-based sorbent cycled for CO2 capture
, FUEL, Vol: 150, Pages: 269-277, ISSN: 0016-2361 -
Conference paperKhairuddin U, Costall AW, Martinez-Botas RF, 2015,
INFLUENCE OF GEOMETRICAL PARAMETERS ON AERODYNAMIC OPTIMIZATIONOF A MIXED-FLOW TURBOCHARGER TURBINE
, ASME Turbo Expo 2015: Turbine Technical Conference and Exposition, Publisher: ASMEThis paper describes an optimization procedure to modify the geometry of a mixed-flow turbocharger turbine for improved aerodynamic efficiency. The procedure integrates parameterization of the turbine blade geometry, genetic algorithm optimization, and 3D CFD analysis using a commercial solver.Using a known mixed-flow turbocharger turbine as the baseline, the main features of the blade geometry — the hub, shroud, camberline, leading and trailing edge profiles—were separately adjusted by the genetic algorithm in the direction of better efficiency. Apart from optimizing the subject turbine for the operating point in question, more usefully this permits each geometrical feature to be ranked by their contribution to the change in efficiency. Cases were also run in which the hub and shroud curves were simultaneously adjusted. Analysis of CFD results provides additional insight into the underlying reasons for efficiency changes by examination of the relevant flow field features.The hub and shroud profiles were observed to have the greatest impact on turbine performance, optimization of which leads to an increase of 1.3 percentage points of efficiency. This compares to only 0.2 percentage points improvement following optimization of the outlet geometry.
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Journal articleDuboviks V, Lomberg M, Maher RC, et al., 2015,
Carbon deposition behaviour in metal-infiltrated gadolinia doped ceria electrodes for simulated biogas upgrading in solid oxide electrolysis cells
, Journal of Power Sources, Vol: 293, Pages: 912-921, ISSN: 1873-2755One of the attractive applications for reversible Solid Oxide Cells (SOCs) is to convert CO2 into CO via high temperature electrolysis, which is particularly important for biogas upgrading. To improve biogas utility, the CO2 component can be converted into fuel via electrolysis. A significant issue for SOC operation on biogas is carbon-induced catalyst deactivation. Nickel is widely used in SOC electrodes for reasons of cost and performance, but it has a low tolerance to carbon deposition. Two different modes of carbon formation on Ni-based electrodes are proposed in the present work based on ex-situ Raman measurements which are in agreement with previous studies. While copper is known to be resistant towards carbon formation, two significant issues have prevented its application in SOC electrodes – namely its relatively low melting temperature, inhibiting high temperature sintering, and low catalytic activity for hydrogen oxidation. In this study, the electrodes were prepared through a low temperature metal infiltration technique. Since the metal infiltration technique avoids high sintering temperatures, Cu–Ce0.9Gd0.1O2−δ (Cu-CGO) electrodes were fabricated and tested as an alternative to Ni-CGO electrodes. We demonstrate that the performance of Cu-CGO electrodes is equivalent to Ni-CGO electrodes, whilst carbon formation is fully suppressed when operated on biogas mixture.
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Journal articleBuytaert W, Almeida S, le vine N, et al., 2015,
Accounting for dependencies in regionalized signatures for predictions in ungauged catchments
, Hydrology and Earth System Sciences Discussions, Vol: 12, Pages: 5389-5426, ISSN: 1812-2116A recurrent problem in hydrology is the absence of streamflow data to calibrate rainfall-runoff models. A commonly used approach in such circumstances conditions model parameters on regionalized response signatures. While several different signatures are often available to be included in this process, an outstanding challenge is the selection of signatures that provide useful and complementary information. Different signatures do not necessarily provide independent information, and this has led to signatures being omitted or included on a subjective basis. This paper presents a method that accounts for the inter-signature error correlation structure so that regional information is neither neglected nor double-counted when multiple signatures are included. Using 84 catchments from the MOPEX database, observed signatures are regressed against physical and climatic catchment attributes. The derived relationships are then utilized to assess the joint probability distribution of the signature regionalization errors that is subsequently used in a Bayesian procedure to condition a rainfall-runoff model. The results show that the consideration of the inter-signature error structure may improve predictions when the error correlations are strong. However, other uncertainties such as model structure and observational error may outweigh the importance of these correlations. Further, these other uncertainties cause some signatures to appear repeatedly to be disinformative.
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Journal articleShin HH, Cohen AJ, Pope CA, et al., 2015,
Meta-Analysis Methods to Estimate the Shape and Uncertainty in the Association Between Long-Term Exposure to Ambient Fine Particulate Matter and Cause-Specific Mortality Over the Global Concentration Range
, RISK ANALYSIS, Vol: 36, Pages: 1813-1825, ISSN: 0272-4332 -
Journal articleThuburn J, Cotter CJ, 2015,
A primal-dual mimetic finite element scheme for the rotating shallow water equations on polygonal spherical meshes
, JOURNAL OF COMPUTATIONAL PHYSICS, Vol: 290, Pages: 274-297, ISSN: 0021-9991 -
Journal articleLomax G, Lenton TM, Adeosun A, et al., 2015,
COMMENTARY: Investing in negative emissions
, NATURE CLIMATE CHANGE, Vol: 5, Pages: 498-500, ISSN: 1758-678X- Author Web Link
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- Citations: 44
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Journal articleWang L-P, Ochoa-Rodríguez S, Van Assel J, et al., 2015,
Enhancement of radar rainfall estimates for urban hydrology through optical flow temporal interpolation and Bayesian gauge-based adjustment
, Journal of Hydrology, Vol: 531, Pages: 408-426, ISSN: 0022-1694Rainfall estimates of the highest possible accuracy and resolution are required for urban hydrological applications, given the small size and fast response which characterise urban catchments. While radar rainfall estimates have the advantage of well capturing the spatial structure of rainfall fields and its variation in time, the commonly available radar rainfall products (typically at ∼1 km/5–10 min resolution) may still fail to satisfy the accuracy and resolution – in particular temporal resolution – requirements of urban hydrology. A methodology is proposed in this paper, to produce higher temporal resolution, more accurate radar rainfall estimates, suitable for urban hydrological applications. The proposed methodology entails two main steps: (1) Temporal interpolation of radar images from the originally-available temporal resolutions (i.e. 5–10 min) to finer resolutions at which local rain gauge data are commonly available (i.e. 1–2 min). This is done using a novel interpolation technique, based upon the multi-scale variational optical flow technique, and which can well capture the small-scale rainfall structures relevant at urban scales. (2) Local and dynamic gauge-based adjustment of the higher temporal resolution radar rainfall estimates is performed afterwards, by means of the Bayesian data merging method. The proposed methodology is tested using as case study a total of 8 storm events observed in the Cranbrook (UK) and Herent (BE) urban catchments, for which radar rainfall estimates, local rain gauge and depth/flow records, as well as recently calibrated urban drainage models were available. The results suggest that the proposed methodology can provide significantly improved radar rainfall estimates and thereby generate more accurate runoff simulations at urban scales, over and above the benefits derived from the mere application of Bayesian merging at the original temporal resolution at which radar estimates are available
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Journal articleAndersen ZJ, de Nazelle A, Mendez MA, et al., 2015,
A study of the combined effects of physical activity and air pollution on mortality in elderly urban residents: the Danish diet, cancer, and health cohort
, Environmental Health Perspectives, Vol: 123, Pages: 557-563, ISSN: 1552-9924Background: Physical activity reduces, whereas exposure to air pollution increases, the risk of premature mortality. Physical activity amplifies respiratory uptake and deposition of air pollutants in the lung, which may augment acute harmful effects of air pollution during exercise.Objectives: We aimed to examine whether benefits of physical activity on mortality are moderated by long-term exposure to high air pollution levels in an urban setting.Methods: A total of 52,061 subjects (50–65 years of age) from the Danish Diet, Cancer, and Health cohort, living in Aarhus and Copenhagen, reported data on physical activity in 1993–1997 and were followed until 2010. High exposure to air pollution was defined as the upper 25th percentile of modeled nitrogen dioxide (NO2) levels at residential addresses. We associated participation in sports, cycling, gardening, and walking with total and cause-specific mortality by Cox regression, and introduced NO2 as an interaction term.Results: In total, 5,534 subjects died: 2,864 from cancer, 1,285 from cardiovascular disease, 354 from respiratory disease, and 122 from diabetes. Significant inverse associations of participation in sports, cycling, and gardening with total, cardiovascular, and diabetes mortality were not modified by NO2. Reductions in respiratory mortality associated with cycling and gardening were more pronounced among participants with moderate/low NO2 [hazard ratio (HR) = 0.55; 95% CI: 0.42, 0.72 and 0.55; 95% CI: 0.41, 0.73, respectively] than with high NO2 exposure (HR = 0.77; 95% CI: 0.54, 1.11 and HR = 0.81; 95% CI: 0.55, 1.18, p-interaction = 0.09 and 0.02, respectively).Conclusions: In general, exposure to high levels of traffic-related air pollution did not modify associations, indicating beneficial effects of physical activity on mortality. These novel findings require replication in other study populations.
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Journal articleBennett EM, Cramer W, Begossi A, et al., 2015,
Linking biodiversity, ecosystem services, and human well-being: three challenges for designing research for sustainability
, CURRENT OPINION IN ENVIRONMENTAL SUSTAINABILITY, Vol: 14, Pages: 76-85, ISSN: 1877-3435- Author Web Link
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- Citations: 411
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Journal articlePerez L, Wolf K, Hennig F, et al., 2015,
Air pollution and atherosclerosis: a cross-sectional analysis of four European cohort studies in the ESCAPE study
, Environmental Health Perspectives, Vol: 123, Pages: 597-605, ISSN: 1552-9924Background: In four European cohorts, we investigated the cross-sectional association between long-term exposure to air pollution and intima-media thickness of the common carotid artery (CIMT), a preclinical marker of atherosclerosis.Methods: Individually assigned levels of nitrogen dioxide, nitrogen oxides, particulate matter ≤ 2.5 μm (PM2.5), absorbance of PM2.5 (PM2.5abs), PM10, PMcoarse, and two indicators of residential proximity to highly trafficked roads were obtained under a standard exposure protocol (European Study of Cohorts for Air Pollution Effects—ESCAPE study) in the Stockholm area (Sweden), the Ausburg and Ruhr area (Germany), and the Girona area (Spain). We used linear regression and meta-analyses to examine the association between long-term exposure to air pollution and CIMT.Results: The meta-analysis with 9,183 individuals resulted in an estimated increase in CIMT (geometric mean) of 0.72% (95% CI: –0.65%, 2.10%) per 5-μg/m3 increase in PM2.5 and 0.42% (95% CI: –0.46%, 1.30%) per 10–5/m increase in PM2.5abs. Living in proximity to high traffic was also positively but not significantly associated with CIMT. Meta-analytic estimates for other pollutants were inconsistent. Results were similar across different adjustment sets and sensitivity analyses. In an extended meta-analysis for PM2.5 with three other previously published studies, a 0.78% (95% CI: –0.18%, 1.75%) increase in CIMT was estimated for a 5-μg/m3 contrast in PM2.5.Conclusions: Using a standardized exposure and analytical protocol in four European cohorts, we found that cross-sectional associations between CIMT and the eight ESCAPE markers of long-term residential air pollution exposure did not reach statistical significance. The additional meta-analysis of CIMT and PM2.5 across all published studies also was positive but not significant.
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Book chapterWoodward G, 2015,
Freshwater Conservation and Biomonitoring of Structure and Function: Genes to Ecosystems
, Aquatic Functional Biodiversity: An Ecological and Evolutionary Perspective -
Journal articleMaire V, Wright IJ, Prentice IC, et al., 2015,
Global effects of soil and climate on leaf photosynthetic traits and rates
, Global Ecology and Biogeography, Vol: 24, Pages: 706-717, ISSN: 1466-822XAimThe influence of soil properties on photosynthetic traits in higher plants is poorly quantified in comparison with that of climate. We address this situation by quantifying the unique and joint contributions to global leaf‐trait variation from soils and climate.LocationTerrestrial ecosystems world‐wide.MethodsUsing a trait dataset comprising 1509 species from 288 sites, with climate and soil data derived from global datasets, we quantified the effects of 20 soil and 26 climate variables on light‐saturated photosynthetic rate (Aarea), stomatal conductance (gs), leaf nitrogen and phosphorus (Narea and Parea) and specific leaf area (SLA) using mixed regression models and multivariate analyses.ResultsSoil variables were stronger predictors of leaf traits than climatic variables, except for SLA. On average, Narea, Parea and Aarea increased and SLA decreased with increasing soil pH and with increasing site aridity. gs declined and Parea increased with soil available P (Pavail). Narea was unrelated to total soil N. Joint effects of soil and climate dominated over their unique effects on Narea and Parea, while unique effects of soils dominated for Aarea and gs. Path analysis indicated that variation in Aarea reflected the combined independent influences of Narea and gs, the former promoted by high pH and aridity and the latter by low Pavail.Main conclusionsThree environmental variables were key for explaining variation in leaf traits: soil pH and Pavail, and the climatic moisture index (the ratio of precipitation to potential evapotranspiration). Although the reliability of global soil datasets lags behind that of climate datasets, our results nonetheless provide compelling evidence that both can be jointly used in broad‐scale analyses, and that effects uniquely attributable to soil properties are important determinants of leaf photosynthetic traits and rates. A significant future challenge is to better disentangle the covarying physiological, ecological and evolutionary
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Journal articleHills TP, Gordon F, Florin NH, et al., 2015,
Statistical analysis of the carbonation rate of concrete
, CEMENT AND CONCRETE RESEARCH, Vol: 72, Pages: 98-107, ISSN: 0008-8846- Author Web Link
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- Citations: 35
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Journal articleOkada Y, Ekins-Daukes NJ, Kita T, et al., 2015,
Intermediate band solar cells: Recent progress and future directions
, Applied Physics Reviews, Vol: 2, ISSN: 1931-9401 -
Journal articleStaffell I, 2015,
Zero carbon infinite COP heat from fuel cell CHP
, Applied Energy, Vol: 147, Pages: 373-385, ISSN: 0306-2619 -
Journal articleCalvo MM, Prentice IC, 2015,
Effects of fire and CO2 on biogeography and primary production in glacial and modern climates
, New Phytologist, Vol: 208, Pages: 987-994, ISSN: 0028-646XDynamic global vegetation models (DGVMs) can disentangle causes and effects in the control of vegetation and fire. We used a DGVM to analyse climate, CO2 and fire influences on biome distribution and net primary production (NPP) in last glacial maximum (LGM) and pre-industrial (PI) times.The Land surface Processes and eXchanges (LPX) DGVM was run in a factorial design with fire ‘off’ or ‘on’, CO2 at LGM (185 ppm) or PI (280 ppm) concentrations, and LGM (modelled) or recent climates. Results were analysed by Stein–Alpert decomposition to separate primary effects from synergies.Fire removal causes forests to expand and global NPP to increase slightly. Low CO2 greatly reduces forest area (dramatically in a PI climate; realistically under an LGM climate) and global NPP. NPP under an LGM climate was reduced by a quarter as a result of low CO2. The reduction in global NPP was smaller at low temperatures, but greater in the presence of fire.Global NPP is controlled by climate and CO2 directly through photosynthesis, but also through biome distribution, which is strongly influenced by fire. Future vegetation simulations will need to consider the coupled responses of vegetation and fire to CO2 and climate.
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Journal articleLeguy AMA, Frost JM, McMahon AP, et al., 2015,
The dynamics of methylammonium ions in hybrid organic-inorganic perovskite solar cells
, Nature Communications, Vol: 6, ISSN: 2041-1723Methylammonium lead iodide perovskite can make high-efficiency solar cells, which also show an unexplained photocurrent hysteresis dependent on the device-poling history. Here we report quasielastic neutron scattering measurements showing that dipolar CH3NH3+ ions reorientate between the faces, corners or edges of the pseudo-cubic lattice cages in CH3NH3PbI3 crystals with a room temperature residence time of ~14 ps. Free rotation, π-flips and ionic diffusion are ruled out within a 1–200-ps time window. Monte Carlo simulations of interacting CH3NH3+ dipoles realigning within a 3D lattice suggest that the scattering measurements may be explained by the stabilization of CH3NH3+ in either antiferroelectric or ferroelectric domains. Collective realignment of CH3NH3+ to screen a device’s built-in potential could reduce photovoltaic performance. However, we estimate the timescale for a domain wall to traverse a typical device to be ~0.1–1 ms, faster than most observed hysteresis.
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Journal articleParkes MA, Refson K, d'Avezac M, et al., 2015,
Chemical descriptors of yttria-stabilized zirconia at low defect concentration: an ab initio study.
, Journal of Physical Chemistry A, Vol: 119, Pages: 6412-6420, ISSN: 1520-5215Yttria-stabilized zirconia (YSZ) is an important oxide ion conductor with applications in solid oxide fuel cells (SOFCs) and oxygen sensing devices. Doping the cubic phase of zirconia (c-ZrO2) with yttria (Y2O3) is isoelectronic, as two Zr(4+) ions are replaced by two Y(3+) ions, plus a charge compensating oxygen vacancy (Ovac). Typical doping concentrations include 3, 8, 10, and 12 mol %. For these concentrations, and all below 40 mol %, no phase with long-range order has been observed in either X-ray or neutron diffraction experiments. The prediction of local defect structure and the interaction between defects is therefore of great interest. This has not been possible to date as the number of possible defect topologies is very large and to perform reliable total energy calculations for all of them would be prohibitively expensive. Previous theoretical studies have only considered a selection of representative structures. In this study, a comprehensive search for low-energy defect structures using a combined classical modeling and density functional theory approach is used to identify the low-energy isolated defect structures at the dilute limit, 3.2 mol %. Through analysis of energetics computed using the best available Born-Mayer-Huggins empirical potential model, a point charge model, DFT, and a local strain energy estimated in the harmonic approximation, the main chemical and physical descriptors that correlate to the low-energy DFT structures are discussed. It is found that the empirical potential model reproduces a general trend of increasing DFT energetics across a series of locally strain relaxed structures but is unreliable both in predicting some incorrect low-energy structures and in finding some metastable structures to be unstable. A better predictor of low-energy defect structures is found to be the total electrostatic energy of a simple point charge model calculated at the unrelaxed geometries of the defects. In addition, the strain relaxation energ
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Journal articleXu LJ, Chu W, Graham N, 2015,
Sonophotolytic degradation of phthalate acid esters in water and wastewater: Influence of compound properties and degradation mechanisms
, JOURNAL OF HAZARDOUS MATERIALS, Vol: 288, Pages: 43-50, ISSN: 0304-3894- Author Web Link
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- Citations: 23
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