• Energy Research
• US close
• FR close
• BE close
• Nottingham Trent University close

The photoionization of two representative mono-terpenes (R-limonene and R-carvone) has been investigated using low energy synchrotron radiation in the region from the threshold for ionization of these molecules up to 11 eV. Data from threshold photoelectron spectra are interpreted with the aid of Outer Valence Green's Function (OVGF) calculations to identify the character of the outermost orbitals and improved ionization potentials are deduced. Fragmentation of the parent ions is studied using threshold photoelectron-photoion coincidence (TPEPICO) time-of-flight (TOF) mass spectrometry and breakdown diagrams identifying the major products in this near-threshold region are presented.

PAGE is a computer simulation model developed in 1992 for policy analysis of the global warming problem. This paper surveys key developments in understanding the global warming problem that have occurred since 1992. For example, anthropogenic sulphates have been found to have a significant cooling effect. Halocarbons, once thought to be the most potent greenhouse gases, are now believed to have only a slight global warming effect because they destroy ozone, itself a strong greenhouse gas. Furthermore, case studies in various regions of the world have improved our ability to predict future damages from global warming. These developments have strong implications for the economic consequences of the greenhouse effect and motivated an update of the PAGE model. This paper discusses the new model version, PAGE95, and conclusions for global warming policy analysis.

Many subsurface microorganisms couple their metabolism to the reduction or oxidation of extracellular substrates. For example, anaerobic mineral-respiring bacteria can use external metal oxides as terminal electron acceptors during respiration. Porin-cytochrome complexes facilitate the movement of electrons generated through intracellular catabolic processes across the bacterial outer membrane to these terminal electron acceptors. In the mineral-reducing model bacterium Shewanella oneidensis MR-1, this complex is composed of two decaheme cytochromes (MtrA and MtrC) and an outer-membrane β-barrel (MtrB). However, the structures and mechanisms by which porin-cytochrome complexes transfer electrons are unknown. Here, we used small-angle neutron scattering (SANS) to study the molecular structure of the transmembrane complexes MtrAB and MtrCAB. Ab initio modeling of the scattering data yielded a molecular envelope with dimensions of ∼105 × 60 × 35 Å for MtrAB and ∼170 × 60 × 45 Å for MtrCAB. The shapes of these molecular envelopes suggested that MtrC interacts with the surface of MtrAB, extending ∼70 Å from the membrane surface and allowing the terminal hemes to interact with both MtrAB and an extracellular acceptor. The data also reveal that MtrA fully extends through the length of MtrB, with ∼30 Å being exposed into the periplasm. Proteoliposome models containing membrane-associated MtrCAB and internalized small tetraheme cytochrome (STC) indicate that MtrCAB could reduce Fe(III) citrate with STC as an electron donor, disclosing a direct interaction between MtrCAB and STC. Taken together, both structural and proteoliposome experiments support porin-cytochrome-mediated electron transfer via periplasmic cytochromes such as STC.

An investigation into how replacing CdS with ZnS reduces toxicity and alters the power conversion efficiency in photovoltaic devices.

Biomass is an especially reactive fuel. There have been large increases in the transportation and utilisation of biomass fuels over the past 10 years and this has raised concerns over its safe handling and utilisation. Fires, and sometimes explosions, are a risk during all stages of fuel production as well as during the handling and utilisation of the product. This paper presents a method for assessing ignition risk and provides a ranking of relative risk of ignition of biomass fuels. Tests involved single particle measurements, thermal analysis, dust layer and basket ignition tests. In all cases, smouldering combustion was observed, whereby the fuels pyrolyse to produce a black char, which then subsequently ignites. Low temperature pyrolysis kinetics have been utilised to predict ignition delay times at low temperatures. A method for evaluating risk was explored based on the activation energy for pyrolysis and a characteristic temperature from TGA analysis. Here, olive cake, sunflower husk and Miscanthus fall into the high risk category, while the woods, plane, pine, mesquite and red berry juniper, fall into the medium risk category. This method is able to capture the impact of low activation energy for pyrolysis on the increased risk of ignition.

International audience ; Biobinders (binders manufactured from biomass) are becoming popular in asphalt engineering due to growing environmental concerns of greenhouse gas emissions from the use of fossil fuels and depleting petroleum bitumen reserves. Waste biomass products are sources of particular interest due to their widespread availability and impact on sustainability, however, they generally need to be thermochemically treated before being used as biobinders. Although biobinders can exhibit good performance in terms of resisting common distresses affecting road pavements, they are still relatively unknown and the uncertainty around them discourages their further use. In this context, this review aims at providing a link between biomass thermochemical conversion technologies and their respective products that may be used as biobinders in pavement engineering. For this purpose, firstly, a detailed insight of the biomass thermochemical conversion technologies available for the manufacture of biobinders is provided. Specifically, solvent liquefaction and pyrolysis are compared and the operating parameters affecting the production of biobinders from solvent liquefaction are explored. Secondly, the review focuses on providing an overview of current biobinder studies for asphalt mixtures with an emphasis on the feedstock utilised and their key engineering properties. The review shows that biobinders’ performance highly depends on the biomass source and the technology applied to produce them. Summary tables provide researchers with a quick but insightful way of identifying potential biobinder feedstocks according to certain properties.

Despite a growing literature on the climate response to solar geoengineering—proposals to cool the planet by increasing the planetary albedo—there has been little published on the impacts of solar geoengineering on natural and human systems such as agriculture, health, water resources, and ecosystems. An understanding of the impacts of different scenarios of solar geoengineering deployment will be crucial for informing decisions on whether and how to deploy it. Here we review the current state of knowledge about impacts of a solar‐geoengineered climate and identify the major research gaps. We suggest that a thorough assessment of the climate impacts of a range of scenarios of solar geoengineering deployment is needed and can be built upon existing frameworks. However, solar geoengineering poses a novel challenge for climate impacts research as the manner of deployment could be tailored to pursue different objectives making possible a wide range of climate outcomes. We present a number of ideas for approaches to extend the survey of climate impacts beyond standard scenarios of solar geoengineering deployment to address this challenge. Reducing the impacts of climate change is the fundamental motivator for emissions reductions and for considering whether and how to deploy solar geoengineering. This means that the active engagement of the climate impacts research community will be important for improving the overall understanding of the opportunities, challenges, and risks presented by solar geoengineering.

In seeking better predictions of grain yield under light-limited conditions, shading was applied to field-grown winter wheat cv. Slejpner during each of five consecutive phases (canopy expansion, ear expansion, pre-flowering, grain expansion and grain filling). Absolute measures were taken of solar radiation and its effects on growth in three seasons, at a site where water and nutrient supplies were not limiting. Replicate mobile shades automatically occluded 0·80 of incident light when mean total solar radiation exceeded 250 J/m2 per s. Mean effects over seasons of shading on incident total solar radiation were −296, −139, −78, −157 and −357 MJ/m2 for the five phases respectively, and corresponding effects on shoot dry weight were −236, −184, −58, −122 and −105 g/m2. Estimated efficiency of radiation use after flowering was 1·2 g/MJ unshaded, tending to increase with shading. Shading in all phases reduced grain dry matter yield: mean effects over seasons were −106, −64, −61, −93 and −281 g/m2 for the five consecutive shading periods. Shading from GS31–39 increased mean maximum area of the two top leaves from 2700 to 3100 mm2 per leaf but, with fewer stems, canopy size remained unaffected. This and the next shading, from GS39–55, reduced specific leaf weight from 42 g/m2 by 4 and 3 g/m2 respectively, but effects on shoot dry weight were largely due to stem and ear. By flowering, stem weights, and especially their reserves of water-soluble carbohydrates, had partially recovered. Effects on yield of shading from GS31–39 were explained by a reduction in grains/m2 of 3070 from 26109. Shading from GS39–55 reduced grains/m2 by 4211 due to fewer grains per ear, whilst mean weight per grain increased in compensation. Shading from GS55–61 decreased grains/ear by 2·5. Shading from GS61–71 decreased ear growth and reduced stem weight, and at harvest resulted in 4·3 less grains/ear. Effects of the final shading from GS71–87 were fully explained by a reduction in mean dry weight/grain of 10·3 mg. Except for shading from GS71–87, source- and sink-based explanations of grain yield both proved feasible, within the precision of the measurements. Constraints to accurate comparison of source- and sink-based approaches are identified, and the implications for yield forecasting are discussed.