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  • Journal article
    Dimitrov SD, Wheeler S, Niedzialek D, Schroeder BC, Utzat H, Frost JM, Yao J, Gillett A, Tuladhar PS, McCulloch I, Nelson J, Durrant JRet al., 2015,

    Polaron pair mediated triplet generation in polymer/fullerene blends

    , Nature Communications, Vol: 6, ISSN: 2041-1723

    Electron spin is a key consideration for the function of organic semiconductors in light-emitting diodes and solar cells, as well as spintronic applications relying on organic magnetoresistance. A mechanism for triplet excited state generation in such systems is by recombination of electron-hole pairs. However, the exact charge recombination mechanism, whether geminate or nongeminate and whether it involves spin-state mixing is not well understood. In this work, the dynamics of free charge separation competing with recombination to polymer triplet states is studied in two closely related polymer-fullerene blends with differing polymer fluorination and photovoltaic performance. Using time-resolved laser spectroscopic techniques and quantum chemical calculations, we show that lower charge separation in the fluorinated system is associated with the formation of bound electron-hole pairs, which undergo spin-state mixing on the nanosecond timescale and subsequent geminate recombination to triplet excitons. We find that these bound electron-hole pairs can be dissociated by electric fields.
  • Journal article
    Madani K, Khatami S, 2015,

    Water for Energy: Inconsistent Assessment Standards and Inability to Judge Properly

    , Current Sustainable/Renewable Energy Reports, Vol: 2, Pages: 10-16

    The water-energy nexus field is experiencing growing attention to assessing the impacts of energy generation on water resources. Numerous studies in recent years have used a range of metrics and methods for measuring and quantifying the water impacts of energy. This article argues that the field is suffering from a lack of consistency in the interpretation and application of different evaluation metrics due to competition for the development of the ‘correct’ evaluation method. The uncertainties caused by inconsistent analysis methods, assumptions, scales and boundaries make the available information confusing and hamper our abilities to understand comprehensively and judge properly. The article highlights some of the major caveats that need to be considered in using the results of the previous studies and applying the existing metrics for evaluating the impacts of energy production on water resources.
  • Journal article
    Berloff P, 2015,

    Dynamically consistent parameterization of mesoscale eddies. Part I: Simple model

    , Ocean Modelling, Vol: 87, Pages: 1-19, ISSN: 1463-5003

    This work aims at developing a framework for dynamically consistent parameterization of mesoscale eddy effects for use in non-eddy-resolving ocean circulation models. The proposed eddy parameterization framework is successfully tested on the classical, wind-driven double-gyre model, which is solved both with explicitly resolved vigorous eddy field and in the non-eddy-resolving configuration with the eddy parameterization replacing the eddy effects. The parameterization locally approximates transient eddy flux divergence by spatially localized and temporally periodic forcing, referred to as the plunger, and focuses on the linear-dynamics flow solution induced by it. The nonlinear self-interaction of this solution, referred to as the footprint, characterizes and quantifies the induced cumulative eddy forcing exerted on the large-scale flow. We find that spatial pattern and amplitude of the footprint strongly depend on the underlying large-scale and the corresponding relationships provide the basis for the eddy parameterization and its closure on the large-scale flow properties. Dependencies of the footprints on other important parameters of the problem are also systematically analyzed. The parameterization utilizes the local large-scale flow information, constructs and scales the corresponding footprints, and then sums them up over the gyres to produce the resulting eddy forcing field, which is interactively added to the model as an extra forcing. The parameterization framework is implemented in the simplest way, but it provides a systematic strategy for improving the implementation algorithm.
  • Journal article
    Belcher CM, Hadden RM, Rein G, Morgan JV, Artemieva N, Goldin Tet al., 2015,

    An experimental assessment of the ignition of forest fuels by the thermal pulse generated by the Cretaceous-Palaeogene impact at Chicxulub

    , JOURNAL OF THE GEOLOGICAL SOCIETY, Vol: 172, Pages: 175-185, ISSN: 0016-7649
  • Journal article
    Field KJ, Leake JR, Tille S, Allinson KE, Rimington WR, Bidartondo MI, Beerling DJ, Cameron DDet al., 2015,

    From mycoheterotrophy to mutualism: mycorrhizal specificity and functioning in <i>Ophioglossum vulgatum</i> sporophytes

    , NEW PHYTOLOGIST, Vol: 205, Pages: 1492-1502, ISSN: 0028-646X
  • Journal article
    Lomax G, Workman M, Lenton T, Shah Net al., 2015,

    Reframing the policy approach to greenhouse gas removal technologies

    , ENERGY POLICY, Vol: 78, Pages: 125-136, ISSN: 0301-4215
  • Journal article
    Kant M, Romagnoli A, Mamat AMI, Martinez-Botas RFet al., 2015,

    Heavy-duty engine electric turbocompounding

    , PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART D-JOURNAL OF AUTOMOBILE ENGINEERING, Vol: 229, Pages: 457-472, ISSN: 0954-4070
  • Journal article
    Chen C, Kamenkovich I, Berloff P, 2015,

    On the Dynamics of Flows Induced by Topographic Ridges

    , JOURNAL OF PHYSICAL OCEANOGRAPHY, Vol: 45, Pages: 927-940, ISSN: 0022-3670
  • Journal article
    Kamenkovich I, Rypina II, Berloff P, 2015,

    Properties and Origins of the Anisotropic Eddy-Induced Transport in the North Atlantic

    , JOURNAL OF PHYSICAL OCEANOGRAPHY, Vol: 45, Pages: 778-791, ISSN: 0022-3670
  • Journal article
    Muuls M, 2015,

    Exporters, importers and credit constraints

    , Journal of International Economics, Vol: 95, Pages: 333-343, ISSN: 1873-0353

    This paper analyzes the interaction between credit constraints and trading behavior, decomposing trade in extensive and intensive margins. I construct a unique dataset containing firm-level trade transaction data, balance sheets and credit scores from an independent credit insurance company for Belgian manufacturing firms between 1999 and 2007. Firms are more likely to be exporting or importing if they enjoy lower credit constraints. Also, firms that have better credit rating export and import more. Importing and exporting behaviors differ in how both the level and growth of the various margins of trade are related to credit constraints in one important dimension. In the case of exports, it is the intensive and extensive margins of exports in terms of both product and destinations that are significantly associated with credit constraints whereas for imports it is the extensive margin in terms of products only.
  • Journal article
    Mazur C, Contestabile M, Offer GJ, Brandon NPet al., 2015,

    Assessing and comparing German and UK transition policies for electric mobility

    , ENVIRONMENTAL INNOVATION AND SOCIETAL TRANSITIONS, Vol: 14, Pages: 84-100, ISSN: 2210-4224
  • Journal article
    Newton P, Martinez-Botas R, Seiler M, 2015,

    A Three-Dimensional Computational Study of Pulsating Flow Inside a Double Entry Turbine

    , JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME, Vol: 137, ISSN: 0889-504X
  • Journal article
    Malloy AC, Martinez-Botas RF, Lamperth M, 2015,

    Measurement of Magnet Losses in a Surface Mounted Permanent Magnet Synchronous Machine

    , IEEE TRANSACTIONS ON ENERGY CONVERSION, Vol: 30, Pages: 323-330, ISSN: 0885-8969
  • Journal article
    Desiro A, Faccio A, Kaech A, Bidartondo MI, Bonfante Pet al., 2015,

    <i>Endogone</i>, one of the oldest plant-associated fungi, host unique Mollicutes-related endobacteria

    , NEW PHYTOLOGIST, Vol: 205, Pages: 1464-1472, ISSN: 0028-646X
  • Journal article
    Rimington WR, Pressel S, Duckett JG, Bidartondo MIet al., 2015,

    Fungal associations of basal vascular plants: reopening a closed book?

    , NEW PHYTOLOGIST, Vol: 205, Pages: 1394-1398, ISSN: 0028-646X
  • Journal article
    AghaKouchak A, Norouzi H, Madani K, Mirchi A, Azarderakhsh M, Nazemi A, Nasrollahi N, Farahmand A, Mehran A, Hasanzadeh Eet al., 2015,

    Aral Sea syndrome desiccates Lake Urmia: Call for action

    , JOURNAL OF GREAT LAKES RESEARCH, Vol: 41, Pages: 307-311, ISSN: 0380-1330
  • Journal article
    Templeton MR, Hammoud AS, Butler AP, Braun L, Foucher JA, Grossmann J, Boukari M, Faye S, Jourda JPet al., 2015,

    Nitrate pollution of groundwater by pit latrines in developing countries

    , AIMS Environmental Science, Vol: 2, Pages: 302-313
  • Journal article
    Togashi HF, Prentice IC, Evans BJ, Forrester DI, Drake P, Feikema P, Brooksbank K, Eamus D, Taylor Det al., 2015,

    Morphological and moisture availability controls of the leaf area-to-sapwood area ratio: analysis of measurements on Australian trees

    , ECOLOGY AND EVOLUTION, Vol: 5, Pages: 1263-1270, ISSN: 2045-7758

    The leaf area-to-sapwood area ratio (LA:SA) is a key plant trait that links photosynthesis to transpiration. The pipe model theory states that the sapwood cross-sectional area of a stem or branch at any point should scale isometrically with the area of leaves distal to that point. Optimization theory further suggests that LA:SA should decrease toward drier climates. Although acclimation of LA:SA to climate has been reported within species, much less is known about the scaling of this trait with climate among species. We compiled LA:SA measurements from 184 species of Australian evergreen angiosperm trees. The pipe model was broadly confirmed, based on measurements on branches and trunks of trees from one to 27 years old. Despite considerable scatter in LA:SA among species, quantile regression showed strong (0.2 < R1 < 0.65) positive relationships between two climatic moisture indices and the lowermost (5%) and uppermost (5–15%) quantiles of log LA:SA, suggesting that moisture availability constrains the envelope of minimum and maximum values of LA:SA typical for any given climate. Interspecific differences in plant hydraulic conductivity are probably responsible for the large scatter of values in the mid-quantile range and may be an important determinant of tree morphology.
  • Journal article
    Goldberg SJ, Ball GI, Allen BC, Schladow SG, Simpson AJ, Masoom H, Soong R, Graven HD, Aluwihare LIet al., 2015,

    Refractory dissolved organic nitrogen accumulation in high-elevation lakes

    , Nature Communications, Vol: 6, ISSN: 2041-1723

    The role of dissolved organic matter (DOM) as either a sink for inorganic nutrients or anadditional nutrient source is an often-neglected component of nutrient budgets in aquaticenvironments. Here, we examined the role of DOM in reactive nitrogen (N) storage in SierraNevada (California, USA) lakes where atmospheric deposition of N has shifted the lakestoward seasonal phosphorus (P)-limitation. Nuclear magnetic resonance (NMR) spectroscopyand isotope analyses performed on DOM isolated from Lake Tahoe reveal the accumulationof refractory proteinaceous material with a 100–200-year residence time. Incontrast, smaller lakes in the same watershed contain DOM with typical terrestrial characteristics,indicating that proteins in Lake Tahoe are autochthonously produced. These datasupport the role of DOM as a possible sink for reactive N in these lake ecosystems andidentify a potential role for DOM in affecting the inorganic nutrient stoichiometry of theseenvironments.
  • Journal article
    Bakewell C, White AJP, Long NJ, Williams CKet al., 2015,

    Scandium and Yttrium Phosphasalen Complexes as Initiators for Ring-Opening Polymerization of Cyclic Esters

    , Inorganic Chemistry, Vol: 54, Pages: 2204-2212, ISSN: 1520-510X
  • Journal article
    Paul S, Zhu Y, Romain C, Brooks R, Saini PK, Williams CKet al., 2015,

    Ring-opening copolymerization (ROCOP): synthesis and properties of polyesters and polycarbonates

    , Chemical Communications, Vol: 51, Pages: 6459-6479, ISSN: 1364-548X

    Controlled routes to prepare polyesters and polycarbonates are of interest due to the widespread application of these materials and the opportunities provided to prepare new copolymers. Furthermore, ring-opening copolymerization may enable new poly(ester–carbonate) materials to be prepared which are inaccessible using alternative polymerizations. This review highlights recent advances in the ring-opening copolymerization catalysis, using epoxides coupled with anhydrides or CO2, to produce polyesters and polycarbonates. In particular, the structures and performances of various homogeneous catalysts are presented for the epoxide–anhydride copolymerization. The properties of the resultant polyesters and polycarbonates are presented and future opportunities highlighted for developments of both the materials and catalysts.
  • Journal article
    Tauxe L, Sugisaki S, Jimenez-Espejo F, Escutia C, Cook CP, van de Flierdt T, Iwai Met al., 2015,

    Geology of the Wilkes land sub-basin and stability of the East Antarctic Ice Sheet: Insights from rock magnetism at IODP Site U1361

    , EARTH AND PLANETARY SCIENCE LETTERS, Vol: 412, Pages: 61-69, ISSN: 0012-821X
  • Journal article
    Hardwick SR, Toumi R, Pfeifer M, Turner EC, Nilus R, Ewers RMet al., 2015,

    The relationship between leaf area index and microclimate in tropical forest and oil palm plantation: Forest disturbance drives changes in microclimate

    , Agricultural and Forest Meteorology, Vol: 201, Pages: 187-195, ISSN: 0168-1923

    Land use change is a major threat to biodiversity. One mechanism by which land use change influences biodiversity and ecological processes is through changes in the local climate. Here, the relationships between leaf area index and five climate variables – air temperature, relative humidity, vapour pressure deficit, specific humidity and soil temperature – are investigated across a range of land use types in Borneo, including primary tropical forest, logged forest and oil palm plantation. Strong correlations with the leaf area index are found for the mean daily maximum air and soil temperatures, the mean daily maximum vapour pressure deficit and the mean daily minimum relative humidity. Air beneath canopies with high leaf area index is cooler and has higher relative humidity during the day. Forest microclimate is also found to be less variable for sites with higher leaf area indices. Primary forest is found to be up to 2.5 °C cooler than logged forest and up to 6.5 °C cooler than oil palm plantations. Our results indicate that leaf area index is a useful parameter for predicting the effects of vegetation upon microclimate, which could be used to make small scale climate predictions based on remotely sensed data.
  • Journal article
    Gambhir A, Tse LKC, Tong D, Martinez-Botas Ret al., 2015,

    Reducing China’s road transport sector CO2 emissions to 2050: Technologies, costs and decomposition analysis

    , Applied Energy, Vol: 157, Pages: 905-917, ISSN: 1872-9118

    The growth of China’s road transport sector has driven huge increases in China’s oil demand and CO2 emissions over the last two decades, and these trends are likely to continue in the absence of specific measures to reduce the average carbon intensity of road vehicles. This paper describes a model, provided in full online, to undertake scenario analysis on the cost and CO2 emissions impact of substituting current vehicle drivetrain types with alternatives during the period 2010–2050. A detailed decomposition of the additional costs and CO2 emissions savings of each low-carbon vehicle type into their component parts is undertaken to calculate the marginal abatement cost of each vehicle and drivetrain type in 2050. The results indicate that passenger cars and heavy-duty trucks constitute the majority of future CO2 emissions savings potential, but that, using the central cost assumptions, alternative vehicle drivetrains are significantly more cost-effective for trucks than passenger cars. The low-carbon scenario sees demand for oil products (gasoline and diesel) more than 40% below the business-as-usual scenario in 2050. The total mitigation cost in 2050 is (US2010)$64 billion per year, or 1.3% of the total annual expenditure on road transport in China in 2050, using a discount rate of 5% to annualise vehicle purchase costs, although this cost increases with higher discount rates. A sensitivity analysis demonstrates that measures in addition to those assumed in the low-carbon scenario could achieve further emissions reductions, in some cases at negative costs. The availability and transparency of the model allows testing and development of a range of further scenarios and sensitivities, to aid in planning an optimal decarbonisation strategy for this highly carbon-intensive sector.
  • Journal article
    Lynd LR, Sow M, Chimphango AFA, Cortez LAB, Brito Cruz CH, Elmissiry M, Laser M, Mayaki IA, Moraes MAFD, Nogueira LAH, Wolfaardt GM, Woods J, van Zyl WHet al., 2015,

    Bioenergy and African transformation

    , Biotechnology for Biofuels, Vol: 8, ISSN: 1754-6834
  • Journal article
    Dodds PE, Staffell L, Hawkes AD, Li F, Grunewald P, McDowall W, Ekins Pet al., 2015,

    Hydrogen and fuel cell technologies for heating: A review

    , International Journal of Hydrogen Energy, Vol: 40, Pages: 2065-2083, ISSN: 1879-3487
  • Report
    Green RJ, Staffell I, 2015,

    Evidence on Wind Farm Performance Decline in the UK

    , Evidence on Wind Farm Performance Decline in the UK

    Onshore wind farms in the UK have aged at about the same rate as other kinds ofpower station. The average wind farm has an annual load factor of about 28% whenfirst commissioned, which declines by about 0.4 percentage points per year. After 15years, the load factor would have fallen to 23%. This ageing does not appear to havemade developers replace their farms early. Forty out of the first forty-five windfarms commissioned in the UK were still operating at this age; four had beenrepowered. Taking this deterioration into account raises the levelised cost ofelectricity by around 9% over a 24-year lifespan, discounting at 10 per cent a year.This is a summary of the peer-reviewed paper “How does wind farm performancedecline with age?” published in Renewable Energy, vol. 65, pp 775-786, which isavailable to download from http://tinyurl.com/wind-decline.
  • Journal article
    Emmott CJM, Roehr JA, Campoy-Quiles M, Kirchartz T, Urbina A, Ekins-Daukes NJ, Nelson Jet al., 2015,

    Organic photovoltaic greenhouses: a unique application for semi-transparent PV?

    , Energy & Environmental Science, Vol: 8, Pages: 1317-1328, ISSN: 1754-5706

    Organic photovoltaics are an emerging solar power technology which embody properties such astransparency, flexibility, and rapid, roll to roll manufacture, opening the potential for unique nicheapplications. We report a detailed techno-economic analysis of one such application, namely thephotovoltaic greenhouse, and discuss whether the unique properties of the technology can provideadvantages over conventional photovoltaics. The potential for spectral selectivity through the choice ofOPV materials is evaluated for the case of a photovoltaic greenhouse. The action spectrum of typicalgreenhouse crops is used to determine the impact on crop growth of blocking different spectral rangesfrom the crops. Transfer matrix optical modelling is used to assess the efficiency and spectrally resolvedtransparency of a variety of commercially available semi-conducting polymer materials, in addition to anon-commercial low-band-gap material with absorption outside that required for crop growth. Economicanalysis suggests there could be a huge potential for OPV greenhouses if aggressive cost targets can bemet. Technical analysis shows that semi-transparent OPV devices may struggle to perform better thanopaque crystalline silicon with partial coverage, however, OPV devices using the low-band-gap materialPMDPP3T, as well as a high efficiency mid-band-gap polymer PCDTBT, can demonstrate improvedperformance in comparison to opaque, flexible thin-film modules such as CIGS. These results stress theimportance of developing new, highly transparent electrode and interlayer materials, along with highefficiency active layers, if the full potential of this application is going to be realised.
  • Journal article
    Rein G, Jervis FX, 2015,

    Experimental study on the burning behaviour of Pinus halepensis needles using small-scale fire calorimetry of live, aged and dead samples

    , Fire and Materials, Vol: 40, Pages: 385-395, ISSN: 1099-1018

    Limited research has been conducted on the burning characteristics of live fuels, which are commonly assumed to behave like moist dead fuels. We use small-scale laboratory calorimetric experiments to investigate the differences in fire dynamics between live and dead Pinus halepensis needles. The study includes laboratory-aged samples and different moisture conditions (fresh or oven dry). A series of ten fire behaviour parameters are extracted from the measurements to identify and quantify differences. The main parameters are the following: time to ignition; flaming time; mass loss pre-ignition, during flaming, and during smouldering; peak power; effective heat of combustion; mean and peak CO/CO2; and radiative fraction. Using these parameters, we show that the most flammable samples are fresh dead and aged needles, followed by dry dead and dry live needles. The least flammable is fresh live needles. Live needles ignite about four times slower, and burn with ~60% lower power and ~50% lower heat of combustion than dead needles. Aged needles resemble most closely the behaviour of dead needles, but many fire behaviour parameters were significantly different. The results confirm the importance of moisture content in the burning behaviour of pine needles, but the differences between live and dead samples cannot be explained solely in terms of moisture but require consideration of plant chemistry and sample drying.
  • Journal article
    Ruiz-Trejo E, Boldrin P, Medley-Hallam JL, Darr J, Atkinson A, Brandon NPet al., 2015,

    Partial oxidation of methane using silver/gadolinia-doped ceria composite membranes

    , Chemical Engineering Science, Vol: 127, Pages: 269-275, ISSN: 1873-4405

    Methane was partially oxidised to CO using oxygen permeated through a 1 mm thick silver/Ce0.9Gd0.1O2−x (Ag/CGO) composite membrane operating at 500–700 °C with air at 1 bar pressure. The membranes were fabricated by sintering ultrafine nanoparticles of gadolinia-doped ceria (<5 nm) coated with silver using Tollens׳ reaction. This unique combination led to dense composites with low content of silver (7 vol%), no reaction between the components and predominant metallic conductivity. When feeding 4% methane at 700 °C to a 1-mm thick Ag/CGO using Ni as reforming catalyst, the conversion reached 21% and the CO selectivity 92% with an estimated oxygen flux of 0.18 mL min−1 cm−2 (NTP). The samples were stable in carbon-containing atmospheres and under a large pO2 transmembrane pressure difference at temperatures below 700 °C for 48 h.

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