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Journal articleFerrandiz-Mas V, Bond T, Zhang Z, et al., 2016,
Optimising the bioreceptivity of porous glass tiles based on colonization by the alga Chlorella vulgaris
, Science of the Total Environment, Vol: 563-564, Pages: 71-80, ISSN: 0048-9697Green façades on buildings can mitigate greenhouse gas emissions. An option to obtain green facades is through the natural colonisation of construction materials. This can be achieved by engineering bioreceptive materials. Bioreceptivity is the susceptibility of a material to be colonized by living organisms. The aim of this research was to develop tiles made by sintering granular waste glass that were optimised for bioreceptivity of organisms capable of photosynthesis. Tiles were produced by pressing recycled soda-lime glass with a controlled particle size distribution and sintering compacted samples at temperatures between 680 and 740 °C. The primary bioreceptivity of the tiles was evaluated by quantifying colonisation by the algae Chlorella vulgaris (C. vulgaris), which was selected as a model photosynthetic micro-organism. Concentrations of C. vulgaris were measured using chlorophyll-a extraction. Relationships between bioreceptivity and the properties of the porous glass tile, including porosity, sorptivity, translucency and pH are reported. Capillary porosity and water sorptivity were the key factors influencing the bioreceptivity of porous glass. Maximum C. vulgaris growth and colonization was obtained for tiles sintered at 700 °C, with 2 of tile. Bioreceptivity was positively 1 correlated with sorptivity and porosity and negatively correlated with light transmittance. The research demonstrates that the microstructure of porous glass, determined by the processing conditions, significantly influences bioreceptivity. Porous glass tiles with high bioreceptivity that are colonised by photosynthetic algae have the potential to form carbon-negative façades for buildings and green infrastructure.
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Journal articleHerceg TM, Abidin MSZ, Greenhalgh ES, et al., 2016,
Thermosetting hierarchical composites with high carbon nanotube loadings: en route to high performance
, Composites Science and Technology, Vol: 127, Pages: 134-141, ISSN: 0266-3538A wet powder impregnation route to manufacture carbon fibre reinforced thermoplastic composites was adapted to accommodate thermosetting matrices reinforced with high fractions (20 wt%/13.6 vol%) of multiwalled carbon nanotubes (CNTs). The produced carbon fibre prepregs were consolidated into laminates with fibre volume fractions of 50–58% and up to 6.1 vol% CNTs. Microscopic imaging confirmed successful consolidation at intermediate CNT loadings, but some voidage at the highest CNT loading due to the highly viscoelastic uncured matrix. Nonetheless, through-thickness electrical conductivity and Mode I interlaminar fracture toughness were enhanced by as much as 152% and 24% to unprecedented values of σ = 53 S m−1 and GIC = 840 J m−2, respectively. Fractographic characterisation indicated that crack deflection was the mechanism responsible for the improved fracture toughness. The material properties were shown to be strongly dependent on the microstructure of the matrix.
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Journal articleSweeney S, Leo BF, Chen S, et al., 2016,
Pulmonary surfactant mitigates silver nanoparticle toxicity in human alveolar type-I-like epithelial cells.
, Colloids and Surfaces B - Biointerfaces, Vol: 145, Pages: 167-175, ISSN: 1873-4367Accompanying increased commercial applications and production of silver nanomaterials is an increased probability of human exposure, with inhalation a key route. Nanomaterials that deposit in the pulmonary alveolar region following inhalation will interact firstly with pulmonary surfactant before they interact with the alveolar epithelium. It is therefore critical to understand the effects of human pulmonary surfactant when evaluating the inhalation toxicity of silver nanoparticles. In this study, we evaluated the toxicity of AgNPs on human alveolar type-I-like epithelial (TT1) cells in the absence and presence of Curosurf(®) (a natural pulmonary surfactant substitute), hypothesising that the pulmonary surfactant would act to modify toxicity. We demonstrated that 20nm citrate-capped AgNPs induce toxicity in human alveolar type I-like epithelial cells and, in agreement with our hypothesis, that pulmonary surfactant acts to mitigate this toxicity, possibly through reducing AgNP dissolution into cytotoxic Ag(+) ions. For example, IL-6 and IL-8 release by TT1 cells significantly increased 10.7- and 35-fold, respectively (P<0.01), 24h after treatment with 25μg/ml AgNPs. In contrast, following pre-incubation of AgNPs with Curosurf(®), this effect was almost completely abolished. We further determined that the mechanism of this toxicity is likely associated with Ag(+) ion release and lysosomal disruption, but not with increased reactive oxygen species generation. This study provides a critical understanding of the toxicity of AgNPs in target human alveolar type-I-like epithelial cells and the role of pulmonary surfactant in mitigating this toxicity. The observations reported have important implications for the manufacture and application of AgNPs, in particular for applications involving use of aerosolised AgNPs.
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Journal articleRodriguez-Lloveras X, Buytaert W, Benito G, 2016,
Land use can offset climate change induced increases in erosion in Mediterranean watersheds
, CATENA, Vol: 143, Pages: 244-255, ISSN: 0341-8162The aim of this paper is to assess the impacts of projected climate change on a Mediterranean catchment, and to analyze the effects of a suite of representative land use practices as an adaptation tool to reduce climate change-driven erosion and hydrologic extremes. Relevant climatic variables from the ERA-Interim global atmospheric reanalysis of the European Centre for Medium-Range Weather Forecasts (ECMWF) were downscaled for the study area, and perturbed with the anomalies of 23 global circulation models for three emission scenarios (B1, A1B and A2). Both a projected daily rainfall time series for the period 2010–2100, and a single precipitation event with a one-hundred year return period were used to assess the impact of climate change. The downscaled data were fed into a distributed hydro-sedimentary model (TETIS) with five land use configurations representative of future demographic tendencies, geographical characteristics and land management policies (e.g. European Union CAP). The projected changes showed a general decrease in runoff and sediment production by the end of the century regardless of land use configuration. Sediment production showed a positive relationship with an increase in agricultural land and a decrease in natural land under present day agricultural management. According to our simulations, some conservation practices in agriculture can effectively reduce net erosion while maintaining agricultural production. As such, they can play a critical role as an adaptation tool to reduce climate change impacts in the 21st century.
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Journal articleKempf A, Mumford J, Levontin P, et al., 2016,
The MSY concept in a multi-objective fisheries environment - Lessons from the North Sea
, Marine Policy, Vol: 69, Pages: 146-158, ISSN: 1872-9460One of the most important goals in current fisheries management is to maintain or restore stocks above levels that can produce the maximum sustainable yield (MSY). However, it may not be feasible to achieve MSY simultaneously for multiple species because of trade-offs that result from interactions between species, mixed fisheries and the multiple objectives of stakeholders. The premise in this study is that MSY is a concept that needs adaptation, not wholesale replacement. The approach chosen to identify trade-offs and stakeholder preferences involved a process of consulting and discussing options with stakeholders as well as scenario modelling with bio-economic and multi-species models. It is difficult to intuitively anticipate the consequences of complex trade-offs and it is also complicated to address them from a political point of view. However, scenario modelling showed that the current approach of treating each stock separately and ignoring trade-offs may result in unacceptable ecosystem, economic or social effects in North Sea fisheries. Setting FMSY as a management target without any flexibility for compromises may lead to disappointment for some of the stakeholders. To treat FMSY no longer as a point estimate but rather as a “Pretty Good Yield” within sustainable ranges was seen as a promising way forward to avoid unacceptable outcomes when trying to fish all stocks simultaneously at FMSY. This study gives insights on how inclusive governance can help to reach consensus in difficult political processes, and how science can be used to make informed decisions inside a multi-dimensional trade-off space.
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Journal articleWoodward G, Bonada N, Brown LE, et al., 2016,
The effects of climatic fluctuations and extreme events on running water ecosystems
, Philisophical Transactions of the Royal Society B, Vol: 371, ISSN: 0962-8436Most research on the effects of environmental change in freshwaters hasfocused on incremental changes in average conditions, rather than fluctuationsor extreme events such as heatwaves, cold snaps, droughts, floodsor wildfires, which may have even more profound consequences. Suchevents are commonly predicted to increase in frequency, intensity and durationwith global climate change, with many systems being exposed toconditions with no recent historical precedent. We propose a mechanisticframework for predicting potential impacts of environmental fluctuationson running-water ecosystems by scaling up effects of fluctuations from individualsto entire ecosystems. This framework requires integration of four keycomponents: effects of the environment on individual metabolism, metabolicand biomechanical constraints on fluctuating species interactions,assembly dynamics of local food webs, and mapping the dynamics of themeta-community onto ecosystem function. We illustrate the framework bydeveloping a mathematical model of environmental fluctuations on dynamicallyassembling food webs. We highlight (currently limited) empiricalevidence for emerging insights and theoretical predictions. For example,widely supported predictions about the effects of environmental fluctuationsare: high vulnerability of species with high per capita metabolic demandssuch as large-bodied ones at the top of food webs; simplification of foodweb network structure and impaired energetic transfer efficiency; andreduced resilience and top-down relative to bottom-up regulation of foodweb and ecosystem processes. We conclude by identifying key questionsand challenges that need to be addressed to develop more accurate and predictivebio-assessments of the effects of fluctuations, and implications offluctuations for management practices in an increasingly uncertain world.
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Journal articleGulliver J, de Hoogh K, Hoek G, et al., 2016,
Back-extrapolated and year-specific NO2 land use regression models for Great Britain - Do they yield different exposure assessment?
, Environment International, Vol: 92-93, Pages: 202-209, ISSN: 1873-6750Robust methods to estimate historic population air pollution exposures are important tools for epidemiological studies evaluating long-term health effects. We developed land use regression (LUR) models for NO2 exposure in Great Britain for 1991 and explored whether the choice of year-specific or back-extrapolated LUR yields 1) similar LUR variables and model performance, and 2) similar national and regional address-level and small-area concentrations. We constructed two LUR models for 1991using NO2 concentrations from the diffusion tube monitoring network, one using 75% of all available measurement sites (that over-represent industrial areas), and the other using 75% of a subset of sites proportionate to population by region to study the effects of monitoring site selection bias. We compared, using the remaining (hold-out) 25% of monitoring sites, the performance of the two 1991 models with back-extrapolation of a previously published 2009 model, developed using NO2 concentrations from automatic chemiluminescence monitoring sites and predictor variables from 2006/2007. The 2009 model was back-extrapolated to 1991 using the same predictors (1990 & 1995) used to develop 1991 models. The 1991 models included industrial land use variables, not present for 2009. The hold-out performance of 1991 models (mean-squared-error-based-R2: 0.62–0.64) was up to 8% higher and ~ 1 μg/m3 lower in root mean squared error than the back-extrapolated 2009 model, with best performance from the subset of sites representing population exposures. Year-specific and back-extrapolated exposures for residential addresses (n = 1.338,399) and small areas (n = 10.518) were very highly linearly correlated for Great Britain (r > 0.83). This study suggests that year-specific model for 1991 and back-extrapolation of the 2009 LUR yield similar exposure assessment.
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Journal articleSiegert MJ, 2016,
A wide variety of unique environments beneath the Antarcticice sheet
, Geology, Vol: 44, Pages: 399-400, ISSN: 0091-7613It is 20 years since subglacial Lake Vostok in central East Antarcticawas found to be one of the world’s largest freshwater bodies (Kapitsa et al.,1996). It was hypothesized to be both an ancient, extreme yet viable environmentfor microbial life, and a recorder of past climate change. Testingthese hypotheses is possible with direct measurement and sampling, butin-situ examination is challenging because of the thick ice to drill through,the necessary cleanliness required of the experiment, and the extremepolar conditions in which to operate. In this issue of Geology, Michaudet al. (2016, p. 347) report on water and sedimentary material collectedin January 2013 from Lake Whillans, a component of the hydrologicalsystem beneath Whillans ice stream in West Antarctica. They reveal thewater comprises melted basal ice and a small proportion of seawater, theconcentration of which increases with sediment depth, making it uniqueamong known subglacial environments within and outside of Antarctica.Here, to place the Lake Whillans work in context, I discuss the range ofAntarctic subglacial lake environments, showing the continent to containan assortment of systems in which novel physical, chemical, and biologicalprocesses may take place.
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Journal articleGreen RJ, Staffell, 2016,
Electricity in Europe: exiting fossil fuels?
, Oxford Review of Economic Policy, Vol: 32, Pages: 282-303, ISSN: 1460-2121There are many options for generating electricity with low carbon emissions, and the electrification of heatand transport can decarbonise energy use across the economy. This places the power sector at the forefrontof any move away from fossil fuels, even though fossil-fuelled generators are more dependable and flexiblethan nuclear reactors or intermittent renewables, and vital for the second-by-second balancing of supply anddemand. Renewables tend to supplement, rather than replace, fossil capacity, although output from fossilfuelledstations will fall and some will have to retire to avoid depressing wholesale power prices. At times oflow demand and high renewable output prices can turn negative, but electricity storage, long-distanceinterconnection and flexible demand may develop to absorb any excess generation. Simulations for GreatBritain show that while coal may be eliminated from the mix within a decade, natural gas has a long-termrole in stations with or without carbon capture and storage, depending on its cost and the price of carbon.
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Journal articlePrat-Guitart N, Rein G, Hadden RM, et al., 2016,
Effects of spatial heterogeneity in moisture content on the horizontal spread of peat fires
, Science of the Total Environment, Vol: 572, Pages: 1422-1430, ISSN: 0048-9697The gravimetric moisture content of peat is the main factor limiting the ignition and spread propagation of smouldering fires. Our aim is to use controlled laboratory experiments to better understand how the spread of smouldering fires is influenced in natural landscape conditions where the moisture content of the top peat layer is not homogeneous. In this paper, we study for the first time the spread of peat fires across a spatial matrix of two moisture contents (dry/wet) in the laboratory. The experiments were undertaken using an open-top insulated box (22. ×. 18. ×. 6. cm) filled with milled peat. The peat was ignited at one side of the box initiating smouldering and horizontal spread. Measurements of the peak temperature inside the peat, fire duration and longwave thermal radiation from the burning samples revealed important local changes of the smouldering behaviour in response to sharp gradients in moisture content. Both, peak temperatures and radiation in wetter peat (after the moisture gradient) were sensitive to the drier moisture condition (preceding the moisture gradient).Drier peat conditions before the moisture gradient led to higher temperatures and higher radiation flux from the fire during the first 6. cm of horizontal spread into a wet peat patch. The total spread distance into a wet peat patch was affected by the moisture content gradient. We predicted that in most peat moisture gradients of relevance to natural ecosystems the fire self-extinguishes within the first 10. cm of horizontal spread into a wet peat patch. Spread distances of more than 10. cm are limited to wet peat patches below 160% moisture content (mass of water per mass of dry peat). We found that spatial gradients of moisture content have important local effects on the horizontal spread and should be considered in field and modelling studies.
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Journal articleShevchenko I, Berloff P, Guerrero-López D, et al., 2016,
On low-frequency variability of the midlatitude ocean gyres
, Journal of Fluid Mechanics, Vol: 795, Pages: 423-442, ISSN: 1469-7645This paper studies the large-scale low-frequency variability of the wind-driven midlatitude ocean gyres and their western boundary currents, such as the Gulf Stream or Kuroshio, simulated with the eddy-resolving quasi-geostrophic model. We applied empirical orthogonal functions analysis to turbulent flow solutions and statistically extracted robust and significant large-scale decadal variability modes concentrated around the eastward jet extension of the western boundary currents. In order to interpret these statistical modes dynamically, we linearized the governing quasi-geostrophic equations around the time-mean circulation and solved for the corresponding full set of linear eigenmodes with their eigenfrequencies. We then projected the extracted decadal variability on the eigenmodes and found that this variability is a multimodal coherent pattern phenomenon rather than a single mode or a combination of several modes as in the flow regimes preceding developed turbulence.
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Journal articleMawhood RK, Gazis E, de Jong S, et al., 2016,
Production pathways for renewable jet fuel: a review of commercialisation status and future prospects
, Biofuels, Bioproducts and Biorefining, Vol: 10, Pages: 462-484, ISSN: 1932-1031Aviation is responsible for an increasing share of anthropogenic CO2 emissions.Decarbonisation to 2050 is expected to rely on renewable jet fuel (RJF) derived frombiomass, but this represents a radical departure from the existing regime of petroleumbasedfuels. Increased market deployment will require significant cost reductions, alongsideadaptation of existing supply chains and infrastructure.This article maps development and manufacturing efforts for six RJF production pathwaysexpected to reach commercialisation in the next 5-10 years. A Rapid Evidence Assessmentwas conducted to evaluate the technological and commercial maturity of each pathway andprogress towards international certification, using the Commercial Aviation Alternative FuelsInitiative’s Fuel Readiness Level (FRL) framework. Planned and operational facilities havebeen catalogued alongside partnerships with the aviation industry. Policy and economicfactors likely to affect future development and deployment are considered.Hydroprocessed Esters and Fatty Acids (FRL 9) is the most developed pathway. It is ASTMcertified, has fuelled the majority of RJF flights to date, and is produced at threecommercial-scale facilities. Fischer-Tropsch derived fuels are moving towards the start-up offirst commercial facilities (FRL 7-8), although widespread deployment seems unlikely undercurrent market conditions. The Direct Sugars to Hydrocarbons conversion pathway (FRL 5-7)is being championed by Amyris and Total in Brazil, but has yet to be demonstrated at scale.Other pathways are in the demonstration and pilot phases (FRL 4-6).Despite growing interest in RJF, demand and production volumes remain negligible.Development of supportive policy is likely to be critical to future deployment.
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Journal articleAlonso Alvarez D, Ekins-Daukes N, 2016,
Photoluminescence-Based Current-Voltage Characterisation Of Individual Subcells In Multi-Junction Devices
, IEEE Journal of Photovoltaics, Vol: 6, Pages: 1004-1011, ISSN: 2156-3381We demonstrate a photoluminescence based,contactless method to determine the current-voltagecharacteristics of the individual subcells in a multi-junctionsolar cell. The method relies upon the reciprocity relationbetween the absorption and emission properties on a solarcell. Laser light with a suitable energy is used to excitecarriers selectively in one junction and the internal voltagesare deduced from the intensity of the resultingluminescence. The IV curves obtained this way on 1J, 2Jand 6J devices are compared to those obtained usingelectroluminescence. Good agreement is obtained at highinjection conditions while discrepancies at low injection areattributed to in-plane carrier transport.
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Journal articleScheelbeek PFD, Chowdhury MAH, Haines A, et al., 2016,
High concentrations of sodium in drinking water and raised blood pressure in coastal deltas affected by episodic seawater inundations
, Lancet Global Health, Vol: 4, ISSN: 2214-109XBackground In times of seawater inundation in coastal deltas, unprotected drinking water sources, such as ponds andshallow tube wells, take on salt water with each inundation. Daily consumption of these saline sources contributes tooverall sodium intake. Although there is evidence that a high dietary salt intake is an important risk factor forhypertension, little is known about the eff ect of high concentrations of sodium in drinking water on populationhealth. In this longitudinal study, we aimed to measure the eff ect of high concentrations of sodium in drinking wateron blood pressure and to assess the reversibility of raised blood pressure when conventional drinking water sourceswere replaced by low-saline water.Methods We used a multistage sampling process to recruit participants aged 18 years or older from the salinityaffectedsub-districts of Dacope, Batiagatha, and Paikgatchha in coastal Bangladesh. Most participants consumeddrinking water from highly saline sources, such as ponds and tube-wells, while a small percentage had access torainwater. In March, 2013, we recorded: baseline concentrations of sodium in drinking water; participants’ bloodpressure; and personal, lifestyle, and environmental characteristics. During the study period, some study participantsgained access to low-saline drinking water alternatives that were installed for use in the dry season, when water fromponds becomes more saline. In March, 2014, and May, 2014, we made follow-up assessments of drinking watersodium, blood pressure, and repeated the questionnaire about personal, lifestyle, and environmental characteristics.We used generalised linear mixed methods to model the eff ect of drinking water sodium on blood pressure andassess reversibility of raised blood pressure when participants switched from conventional drinking water sources tolow-saline alternatives.Findings We included data from 581 participants in analysis, of which 277 (48%) were male. Median age was 38 years(IQR 30&
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Journal articleCurtin OJ, Yoshida M, Pusch A, et al., 2016,
Quantum cascade photon ratchets for intermediate band solar cells
, IEEE Journal of Photovoltaics, Vol: 6, Pages: 673-678, ISSN: 2156-3381We propose an antimonide-based quantum cascade design to demonstrate the ratchet mechanism for incorporation into the recently suggested photon ratchet intermediate-band solar cell. We realize the photon ratchet as a semiconductor heterostructure in which electrons are optically excited into an intermediate band and spatially decoupled from the valence band through a type-II quantum cascade. This process reduces both radiative and nonradiative recombination and can thereby increase the solar cell efficiency over intermediate-band solar cells. Our design method uses an adaptive simulated annealing genetic algorithm to determine the optimum thicknesses of semiconductor layers in the quantum cascade, allowing efficient transport (via phonon emission) of the electrons away from the interband active region.
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Journal articleBrogan AP, Hallett JP, 2016,
Solubilizing and stabilizing proteins in anhydrous lonic liquids through formation of protein-polymer surfactant nanoconstructs
, Journal of the American Chemical Society, Vol: 138, Pages: 4494-4501, ISSN: 1520-5126Nonaqueous biocatalysis is rapidly becoming a desirable tool for chemical and fuel synthesis in both the laboratory and industry. Similarly, ionic liquids are increasingly popular anhydrous reaction media for a number of industrial processes. Consequently, the use of enzymes in ionic liquids as efficient, environment-friendly, commercial biocatalysts is highly attractive. However, issues surrounding the poor solubility and low stability of enzymes in truly anhydrous media remain a significant challenge. Here, we demonstrate for the first time that engineering the surface of a protein to yield protein-polymer surfactant nanoconstructs allows for dissolution of dry protein into dry ionic liquids. Using myoglobin as a model protein, we show that this method can deliver protein molecules with near native structure into both hydrophilic and hydrophobic anhydrous ionic liquids. Remarkably, using temperature-dependent synchrotron radiation circular dichroism spectroscopy to measure half-denaturation temperatures, our results show that protein stability increases by 55 °C in the ionic liquid as compared to aqueous solution, pushing the solution thermal denaturation beyond the boiling point of water. Therefore, the work presented herein could provide a platform for the realization of biocatalysis at high temperatures or in anhydrous solvent systems.
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Journal articleMac Dowell N, 2016,
About the size of it
, TCE The Chemical Engineer, Pages: 27-30, ISSN: 0302-0797Global anthropogenic CO2 production is vast, currently on the order of 35.5 Gt/yr or slightly > 910 million bbl/day of CO2. Due to serious environmental issues, the world has agreed to mitigate global warming and limit it to no more than 1.5°C above pre-industrial levels by the end of the century. One solution is the conversion of CO2 to useful products, e.g., fuels or plastics or otherwise use the CO2 in processes, e.g., CO2-EOR. This is broadly referred to as carbon capture utilization (CCU). The current scale of global CO2 utilization and the role of CCU option might play in mitigating climate change are discussed.
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Journal articleLeese HS, Govada L, Saridakis E, et al., 2016,
Reductively PEGylated carbon nanomaterials andtheir use to nucleate 3D protein crystals:a comparison of dimensionality
, Chemical Science, Vol: 7, Pages: 2916-2923, ISSN: 2041-6539A range of carbon nanomaterials, with varying dimensionality, were dispersed by a non-damaging and versatile chemical reduction route, and subsequently grafted by reaction with methoxy polyethylene glycol (mPEG) monobromides. The use of carbon nanomaterials with different geometries provides both a systematic comparison of surface modification chemistry and the opportunity to study factors affecting specific applications. Multi-walled carbon nanotubes, single-walled carbon nanotubes, graphite nanoplatelets, exfoliated few layer graphite and carbon black were functionalized with mPEG-Br, yielding grafting ratios relative to the nanocarbon framework between ca. 7 and 135 wt%; the products were characterised by Raman spectroscopy, TGA-MS, and electron microscopy. The functionalized materials were tested as nucleants by subjecting them to rigorous protein crystallization studies. Sparsely functionalized flat sheet geometries proved exceptionally effective at inducing crystallization of six proteins. This new class of nucleant, based on PEG grafted graphene-related materials, can be widely applied to promote the growth of 3D crystals suitable for X-ray crystallography. The association of the protein ferritin with functionalized exfoliated few layer graphite was directly visualized by transmission electron microscopy, illustrating the formation of ordered clusters of protein molecules critical to successful nucleation.
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Conference paperStrapasson A, Woods J, Mbuk K, 2016,
Land Use Futures in Europe: How changes in diet, agricultural practices and forestlands could help reduce greenhouse gas emissions
, Vienna, 23rd European Meetings on Cybernetics and Systems Research (EMCSR), Publisher: Bertalanffy Center for the Study of Systems Science (BCSSS), Pages: 106-109 -
Journal articleLambert RSC, Polak JW, Maier S, et al., 2016,
Optimal phasing of district heating network investments using multi-stage stochastic programming
, International journal of sustainable energy planning and management, Vol: 09, Pages: 57-57 -
Journal articleLeguy AMA, Azarhoosh P, Alonso MI, et al., 2016,
Experimental and theoretical optical properties of methylammonium lead halide perovskites
, Nanoscale, Vol: 8, Pages: 6317-6327, ISSN: 2040-3372The optical constants of methylammonium lead halide single crystals CH3NH3PbX3 (X = I, Br, Cl) are interpreted with high level ab initio calculations using the relativistic quasiparticle self-consistent GW approximation (QSGW). Good agreement between the optical constants derived from QSGW and those obtained from spectroscopic ellipsometry enables the assignment of the spectral features to their respective inter-band transitions. We show that the transition from the highest valence band (VB) to the lowest conduction band (CB) is responsible for almost all the optical response of MAPbI3 between 1.2 and 5.5 eV (with minor contributions from the second highest VB and the second lowest CB). The calculations indicate that the orientation of [CH3NH3]+ cations has a significant influence on the position of the bandgap suggesting that collective orientation of the organic moieties could result in significant local variations of the optical properties. The optical constants and energy band diagram of CH3NH3PbI3 are then used to simulate the contributions from different optical transitions to a typical transient absorption spectrum (TAS).
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Journal articleCavitte M, Blankenship D, Young D, et al., 2016,
Deep radiostratigraphy of the East Antarctic plateau: connectingthe Dome C and Vostok ice core sites
, Journal of Glaciology, Vol: 62, Pages: 323-334, ISSN: 1727-5652Several airborne radar-sounding surveys are used to trace internal reflections around theEuropean Project for Ice Coring in Antarctica Dome C and Vostok ice core sites. Thirteen reflections,spanning the last two glacial cycles, are traced within 200 km of Dome C, a promising region formillion-year-old ice, using the University of Texas Institute for Geophysics High-Capacity RadarSounder. This provides a dated stratigraphy to 2318 m depth at Dome C. Reflection age uncertaintiesare calculated from the radar range precision and signal-to-noise ratio of the internal reflections. Theradar stratigraphy matches well with the Multichannel Coherent Radar Depth Sounder (MCoRDS)radar stratigraphy obtained independently. We show that radar sounding enables the extension of icecore ages through the ice sheet with an additional radar-related age uncertainty of ∼1/3–1/2 that ofthe ice cores. Reflections are extended along the Byrd-Totten Glacier divide, using University ofTexas/Technical University of Denmark and MCoRDS surveys. However, core-to-core connection isimpeded by pervasive aeolian terranes, and Lake Vostok’s influence on reflection geometry. Poorradar connection of the two ice cores is attributed to these effects and suboptimal survey design inaffected areas. We demonstrate that, while ice sheet internal radar reflections are generally isochronaland can be mapped over large distances, careful survey planning is necessary to extend ice core chronologiesto distant regions of the East Antarctic ice sheet.
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Conference paperAlonso Alvarez D, Ekins-Daukes N, 2016,
Quantum wells for high-efficiency photovoltaics
, SPIE OPTO 2016: Physics, Simulation, and Photonic Engineering of Photovoltaic Devices V -
Journal articleFerguson A, Khan U, Walsh M, et al., 2016,
Understanding the dispersion and assembly of bacterial cellulose in organic solvents
, Biomacromolecules, Vol: 17, Pages: 1845-1853, ISSN: 1526-4602The constituent nanofibrils of bacterial cellulose are of interest to many researchers because of their purity and excellent mechanical properties. Mechanisms to disrupt the network structure of bacterial cellulose (BC) to isolate bacterial cellulose nanofibrils (BCN) are limited. This work focuses on liquid-phase dispersions of BCN in a range of organic solvents. It builds on work to disperse similarly intractable nanomaterials, such as single-walled carbon nanotubes, where optimum dispersion is seen for solvents whose surface energies are close to the surface energy of the nanomaterial; bacterial cellulose is shown to disperse in a similar fashion. Inverse gas chromatography was used to determine the surface energy of bacterial cellulose, under relevant conditions, by quantifying the surface heterogeneity of the material as a function of coverage. Films of pure BCN were prepared from dispersions in a range of solvents; the extent of BCN exfoliation is shown to have a strong effect on the mechanical properties of BC films and to fit models based on the volumetric density of nanofibril junctions. Such control offers new routes to producing robust cellulose films of bacterial cellulose nanofibrils.
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Journal articleNixon CW, McNeill LC, Bull JM, et al.,
Rapid spatio-temporal variations in rift structure during development of the Corinth Rift, central Greece
, Tectonics, ISSN: 1944-9194 -
Journal articleMarsham JH, Parker DJ, Todd MC, et al., 2016,
The contrasting roles of water and dust in controlling daily variations in radiative heating of the summertime Saharan heat low
, Atmospheric Chemistry and Physics, Vol: 16, Pages: 3563-3575, ISSN: 1680-7324The summertime Sahara heat low (SHL) is a key component of the West African monsoon (WAM) system. Considerable uncertainty remains over the relative roles of water vapour and dust aerosols in controlling the radiation budget over the Sahara and therefore our ability to explain variability and trends in the SHL, and in turn, the WAM. Here, new observations from Fennec supersite-1 in the central Sahara during June 2011 and June 2012, together with satellite retrievals from GERB, are used to quantify how total column water vapour (TCWV) and dust aerosols (from aerosol optical depth, AOD) control day-to-day variations in energy balance in both observations and ECWMF reanalyses (ERA-I). The data show that the earth-atmosphere system is radiatively heated in June 2011 and 2012. Although the empirical analysis of observational data cannot completely disentangle the roles of water vapour, clouds and dust, the analysis demonstrates that TCWV provides a far stronger control on TOA net radiation, and so the net heating of the earth-atmosphere system, than AOD does. In contrast, variations in dust provide a much stronger control on surface heating, but the decreased surface heating associated with dust is largely compensated by increased atmospheric heating, and so dust control on net TOA radiation is weak. Dust and TCWV are both important for direct atmospheric heating. ERA-I, which assimilated radiosondes from the Fennec campaign, captures the control of TOA net flux by TCWV, with a positive correlation (r = 0.6) between observed and modelled TOA net radiation, despite the use of a monthly dust climatology in ERA-I that cannot capture the daily variations in dustiness. Variations in surface net radiation, and so the vertical profile of radiative heating, are not captured in ERA-I, since it does not capture variations in dust. Results show that ventilation of the SHL by cool moist air leads to a radiative warming, stabilising the SHL with respect to such perturbations. It is k
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Journal articleShaffer MSP, Diba M, Fam DWH, et al., 2016,
Electrophoretic deposition of graphene-related materials: A review of the fundamentals
, Progress in Materials Science, Vol: 82, Pages: 83-117, ISSN: 1873-2208The Electrophoretic Deposition (EPD) of graphene-related materials (GRMs) is an attractive strategy for a wide range of applications. This review paper provides an overview of the fundamentals and specific technical aspects of this approach, highlighting its advantages and limitations, in particular considering the issues that arise specifically from the behaviour and dimensionality of GRMs. Since obtaining a stable dispersion of charged particles is a pre-requisite for successful EPD, the strategies for suspending GRMs in different media are discussed, along with the resulting influence on the deposited film. Most importantly, the kinetics involved in the EPD of GRMs and the factors that cause deviation from linearity in Hamaker’s Law are reviewed. Side reactions often influence both the efficiency of deposition and the nature of the deposited material; examples include the reduction of graphene oxide (GO) and related materials, as well as the decomposition of the suspension medium at high potentials. The microstructural characteristics of GRM deposits, including their degree of reduction and orientation, strongly influence their performance in their intended function. These factors will also determine, to a large extent, the commercial potential of this technique for applications involving GRMs, and are therefore discussed here.
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Journal articleLambelet M, van de Flierdt T, Crocket K, et al., 2016,
Neodymium isotopic composition and concentration in the western North Atlantic Ocean: results from the GEOTRACES GA02 section
, Geochimica et Cosmochimica Acta, Vol: 177, Pages: 1-29, ISSN: 0016-7037The neodymium (Nd) isotopic composition of seawater is commonly used as a proxy to study past changes in the thermohaline circulation. The modern database for such reconstructions is however poor and the understanding of the underlying processes is incomplete. Here we present new observational data for Nd isotopes and concentrations from twelve seawater depth profiles, which follow the flow path of North Atlantic Deep Water (NADW) from its formation region in the North Atlantic to the northern equatorial Atlantic. Samples were collected during two cruises constituting the northern part of the Dutch GEOTRACES transect GA02 in 2010. The results show that the different water masses in the subpolar North Atlantic Ocean, which ultimately constitute NADW, have the following Nd isotope characteristics: Upper Labrador Sea Water (ULSW), εNd = -14.2 ± 0.3; Labrador Sea Water (LSW), εNd = -13.7 ± 0.9; Northeast Atlantic Deep Water (NEADW), εNd = -12.5 ± 0.6; Northwest Atlantic Bottom Water (NWABW), εNd = -11.8 ± 1.4. In the subtropics, where these source water masses have mixed to form NADW, which is exported to the global ocean, upper-NADW is characterised by εNd values of -13.2 ± 1.0 (2sd) and lower-NADW exhibits values of εNd = -12.4 ± 0.4 (2sd). While both signatures overlap within error, the signature for lower-NADW is significantly more radiogenic than the traditionally used value for NADW (εNd = -13.5) due to the dominance of source waters from the Nordic Seas (NWABW and NEADW). Comparison between the concentration profiles and the corresponding Nd isotope profiles with other water mass properties such as salinity, silicate concentrations, neutral densities and chlorofluorocarbon (CFC) concentration provides novel insights into the geochemical cycle of Nd and reveals that different processes are necessary to account for the observed Nd characteristics in the subpolar and su
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Journal articleSiegert MJ, 2016,
Environmental Sciences in the Twenty-First Century
, Frontiers in Environmental Science, Vol: 4, ISSN: 2296-665X -
Journal articleVance T, Roberts J, Moy A, et al., 2016,
Optimal site selection for a high-resolution ice core record in East Antarctica
, Climate of the Past, Vol: 12, Pages: 595-610, ISSN: 1814-9332Ice cores provide some of the best-dated and most comprehensive proxy records, as they yield a vast and growing array of proxy indicators. Selecting a site for ice core drilling is nonetheless challenging, as the assessment of potential new sites needs to consider a variety of factors. Here, we demonstrate a systematic approach to site selection for a new East Antarctic high-resolution ice core record. Specifically, seven criteria are considered: (1) 2000-year-old ice at 300 m depth; (2) above 1000 m elevation; (3) a minimum accumulation rate of 250 mm years−1 IE (ice equivalent); (4) minimal surface reworking to preserve the deposited climate signal; (5) a site with minimal displacement or elevation change in ice at 300 m depth; (6) a strong teleconnection to midlatitude climate; and (7) an appropriately complementary relationship to the existing Law Dome record (a high-resolution record in East Antarctica). Once assessment of these physical characteristics identified promising regions, logistical considerations (for site access and ice core retrieval) were briefly considered. We use Antarctic surface mass balance syntheses, along with ground-truthing of satellite data by airborne radar surveys to produce all-of-Antarctica maps of surface roughness, age at specified depth, elevation and displacement change, and surface air temperature correlations to pinpoint promising locations. We also use the European Centre for Medium-Range Weather Forecast ERA 20th Century reanalysis (ERA-20C) to ensure that a site complementary to the Law Dome record is selected. We find three promising sites in the Indian Ocean sector of East Antarctica in the coastal zone from Enderby Land to the Ingrid Christensen Coast (50–100° E). Although we focus on East Antarctica for a new ice core site, the methodology is more generally applicable, and we include key parameters for all of Antarctica which may be useful for ice core site selection elsewhere and/or for other purposes.
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