Photoionization of the Ne-like Si4+ ion in ground and metastable states in the 110–184-eV photon energy range

We present measurements of the absolute photoionization cross section of the neonlike Si4+ ion over the 110–184 eV photon energy range. The measurements were performed using two independent merged-beam setups at the super-ACO and ASTRID synchrotron-radiation facilities, respectively. Signals produced in the photoionization of the 2p subshell of the Si4+ ion both from the 2p6 1S0 ground state and the 2p53s 3P0,2 metastable levels were observed. Calculations of the 2p photoionization cross sections were carried out using a multi-configuration Dirac-Fock code. They give results in good agreement with the measured spectra. Comparison with other available theoretical results is also presented

Parmodulins Inhibit Thrombus Formation Without Inducing Endothelial Injury Caused by Vorapaxar

Protease-activated receptor-1 (PAR1) couples the coagulation cascade to platelet activation during myocardial infarction and to endothelial inflammation during sepsis. This receptor demonstrates marked signaling bias. Its activation by thrombin stimulates prothrombotic and proinflammatory signaling, whereas its activation by activated protein C (APC) stimulates cytoprotective and antiinflammatory signaling. A challenge in developing PAR1-targeted therapies is to inhibit detrimental signaling while sparing beneficial pathways. We now characterize a novel class of structurally unrelated small-molecule PAR1 antagonists, termed parmodulins, and compare the activity of these compounds to previously characterized compounds that act at the PAR1 ligand–binding site. We find that parmodulins target the cytoplasmic face of PAR1 without modifying the ligand-binding site, blocking signaling through Gαq but not Gα13 in vitro and thrombus formation in vivo. In endothelium, parmodulins inhibit prothrombotic and proinflammatory signaling without blocking APC-mediated pathways or inducing endothelial injury. In contrast, orthosteric PAR1 antagonists such as vorapaxar inhibit all signaling downstream of PAR1. Furthermore, exposure of endothelial cells to nanomolar concentrations of vorapaxar induces endothelial cell barrier dysfunction and apoptosis. These studies demonstrate how functionally selective antagonism can be achieved by targeting the cytoplasmic face of a G-protein–coupled receptor to selectively block pathologic signaling while preserving cytoprotective pathways

Advanced Stochastic Optimization Modeling of the Water-energy-food Nexus for Robust Energy and Agricultural Development: Coal Mining Industry in Shanxi province, China

In this presentation, we discuss a modeling framework able to carry out an integrated systems analysis of interdependent energy-food-water-environmental systems while accounting for the competition to those systems posed by restricted natural resources under inherent uncertainties and systemic risks. The case study focuses on developments of coal industry in water-scarce regions of China. Coal is the main energy source in China responsible for country’s energy security. However, coal-based industries consume large quantities of water, which exacerbates the problem of water scarcity. The model accounts for water consumption by various coal mining, processing, and conversion technologies, as well as water and land requirements by different crops and management systems. Uncertain water supply and demand require robust solutions that would ensure demand-production balances and other (environmental, social) constraints in all scenarios. The model derives robust interdependent strategic and adaptive decisions using the “public-private partnership” principle. Strategic long-term decisions comprise the choice of coal-related technologies, land allocation, crop portfolio, and management technologies, while adaptive decisions concern trade and water management. Systemic risks and energy-food-water security considerations are characterized by quantile-based indicators arising due to systemic interdependencies among the systems and decisions of various stakeholders and potential adversaries. Robust solutions provide insights into how to develop and coordinate, in a sustainable way, the complex linkages and trade-offs, at spatial and temporal scales, between energy, agriculture, and water sectors, as well as how to manage potential systemic risks inherent to them. The model explores new coherent energy-food-water-environmental policies accounting for local-global interdependencies induced by national-international trade, as well as self-sufficient local solutions

Electron and ion stagnation at the collision front between two laser produced plasmas

We report results from a combined optical interferometric and spectrally resolved imaging study on colliding laser produced aluminium plasmas. A Nomarski interferometer was used to probe the spatio-temporal distribution of electron densities at the collision front. Analysis of the resulting interferograms reveals the formation and evolution of a localized electron density feature with a well-defined profile reminiscent of a stagnation layer. Electron stagnation begins at a time delay of 10 ns after the peak of the plasma generating laser pulse. The peak electron density was found to exceed 10^19 cm^−3 and the layer remained well defined up to a time delay of ca 100 ns. Temporally and spectrally resolved optical imaging was also undertaken, to compare the Al^+ ion distribution with that of the 2D electron density profile. This revealed nascent stagnation of singly charged ions at a delay time of 20 ns. We attribute these results to the effects of space charge separation in the seed plasma plumes

Greenhouse gas abatement strategies and costs in French dairy production

The French dairy sector—like the rest of the economy—has to address the challenge of mitigating greenhouse gas (GHG) emissions to curb climate change. Deciding the economically optimal mitigation level and mix of abatement strategies requires knowledge on the cost of reducing GHG emissions. Agricultural bio-economic models can help identify which production-system changes are needed to reduce GHG emissions at different levels of incentives at minimal cost. The results reflect the model structure and parameter set, especially for GHG emissions accounting. Here abatement strategies and related costs for several levels of tax on GHG emissions in French dairy production are compared using four bio-economic models: the three supply models AROPAj, ORFEE and FARMDYN and the global partial equilibrium model GLOBIOM. It is found that between 1% and 6% GHG emissions abatement can be achieved at the current price of the EU allowances without substantially reducing milk production or outsourcing input production such as feed or herd renewal. Costs reflect the planning horizon: mitigation is more expensive when past investments are not amortized. Models that account for demand-side factors show a carbon tax has potential negative impacts on consumers through higher milk prices, but could nevertheless partly offset the reduction in income of farmers simulated by farm models. Model results suggest that promising on-farm GHG emissions abatement strategies include measures that let animals reach their full production potential and moderately intensive land management

Dynamics of the IFMIF very high-intensity beam

AbstractFor the purpose of material studies for future nuclear fusion reactors, the IFMIF deuteron beams present a simultaneous combination of unprecedentedly high intensity (2 × 125 mA CW), power (2 × 5 MW) and space charge. Special considerations and new concepts have been developed in order to overcome these challenges. The global strategy for beam dynamics design of the 40 MeV IFMIF accelerators is presented, stressing on the control of micro-losses, and the possibility of online fine tuning. Start-to-end simulations without and with errors are presented for the prototype accelerator. Considerations about conflicts between halo and emittance minimization are then discussed in this very high space charge context

Effect of polycrystallinity on the optical properties of highly oriented ZnO grown by pulsed laser deposition

We report the results of photoluminescence and reflectance measurements on highly c-axis oriented polycrystalline ZnO grown by pulsed laser deposition. The samples measured were grown under identical conditions and were annealed in-situ at various temperatures for 10-15 min. The band-edge photoluminescence spectra of the material altered considerably with an increase in grain size, with increased free exciton emission and observable excitonic structure in the reflectance spectra. The green band emission also increased with increasing grain size. A deformation potential analysis of the effect of strain on the exciton energy positions of the A- and B-excitons demonstrated that the experimental exciton energies could not be explained solely in terms of sample strain. We propose that electric fields in the samples due to charge trapping at grain boundaries are responsible for the additional perturbation of the excitons. This interpretation is supported by theoretical estimates of the exciton energy perturbation due to electric fields. The behaviour of the green band in the samples provides additional evidence in favour of our model

Optical properties of nanocrystalline ZnO thin films grown using pulsed laser deposition

Raman spectroscopy, x-ray diffractometry, atomic force microscopy, photoluminescence spectroscopy and reflectance spectroscopy have been used to characterize ZnO thin films grown by pulsed laser deposition as a function of the post-growth annealing temperature. Raman results show enhancement and broadening of certain Raman features which correlate with changes in the widths of the x-ray diffraction peaks for samples with varying grain size in the 50-100 nm range. These data suggest that electric fields, arising from charge trapping at grain boundaries, in conjunction with localised and surface phonon modes, are the cause of the intensity enhancement and asymmetry of the Raman features. Band-edge photoluminescence and reflectance spectra also altered considerably with increases in grain size, showing clearly observable excitonic structure in the reflectance spectra. An analysis using a deformation potential Hamiltonian demonstrates that the experimental exciton energies are not explicable solely in terms of sample strain and give additional evidence for electric fields in the samples due to charge trapping at grain boundaries. This is supported by theoretical estimates of the exciton energy perturbation due to electric fields and also by the behaviour of the green band in the samples. Detailed studies show that reflectance spectra in nanocrystalline ZnO differ substantially from bulk material. Interaction of excitons, damped by strong electric field effects, with photons leads to exciton-polaritons with substantial damping, eliminating the normal Fabry-Perot structure seen in thin films. Good qualitative agreement is achieved between the model and data and the conclusions are also in good agreement with the photoluminescence and Raman data. Finally, high intensity optical pumping data of these samples again shows a dependence on grain size. All samples show evidence of high excitation effects and the sample with the largest grain size displays random lasing at room temperature. All our results indicate the very strong influence of electric fields due to charge trapping at grain boundaries on the optical properties of nanocrystalline ZnO

Field emission in ordered arrays of ZnO nanowires prepared by nanosphere lithography and extended Fowler-Nordheim analyses

A multistage chemical method based on nanosphere lithography was used to produce hexagonally patterned arrays of ZnO vertical nanowires, with 1 lm interspacing and aspect ratio 20, with a view to study the effects of emitter uniformity on the current emitted upon application of a dc voltage across a 250 lm vacuum gap. A new treatment, based on the use of analytical expressions for the image-potential correction functions, was applied to the linear region below 2000 V of the Fowler-Nordheim (FN) plot and showed the most suitable value of the work function / in the range 3.3–4.5 eV (conduction band emission) with a Schottky lowering parameter y ~ 0.72 and a field enhancement factor c in the 700–1100 range. A modeled c value of 200 was calculated for an emitter shape of a prolate ellipsoid of revolution and also including the effect of nanowire screening, in fair agreement with the experimental value. The Fowler-Nordheim current densities and effective emission areas were derived as 1011 Am2 and 1017 m2, respectively, showing that field emission likely takes place in an area of atomic dimensions at the tip of the emitter. Possible causes for the observed departure from linear FN plot behavior above 2000 V were discussed