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Fabien Paulot David Paynter Vaishali Naik Sergey Malyshev Raymond Menzel Larry W. Horowitz 《International Journal of Hydrogen Energy》2021,46(24):13446-13460
Hydrogen (H2) has been proposed as an alternative energy carrier to reduce the carbon footprint and associated radiative forcing of the current energy system. Here, we describe the representation of H2 in the GFDL-AM4.1 model including updated emission inventories and improved representation of H2 soil removal, the dominant sink of H2. The model best captures the overall distribution of surface H2, including regional contrasts between climate zones, when vd(H2) is modulated by soil moisture, temperature, and soil carbon content. We estimate that the soil removal of H2 increases with warming (2–4% per K), with large uncertainties stemming from different regional response of soil moisture and soil carbon. We estimate that H2 causes an indirect radiative forcing of 0.84 mW m?2/(Tg(H2)yr?1) or 0.13 mW m?2 ppbv?1, primarily due to increasing CH4 lifetime and stratospheric water vapor production. 相似文献
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Catalytic performance of methacrylate‐based poly‐4‐(dialkylamino)‐pyridines: activity prediction via NMR shifts 下载免费PDF全文
The synthesis of the 4‐(dialkylamino)pyridine derivative 3‐(4‐(pyridin‐4‐yl)piperazin‐1‐yl)propyl methacrylate and its copolymerization with n‐butyl methacrylate are presented. The catalytic activity was evaluated in the acylation of tert‐butanol with acetic anhydride yielding tert‐butyl acetate. It is observed that the activity of polymer‐attached 4‐(dimethylamino)pyridine analogues correlates remarkably well with the chemical shift of the β‐pyridyl protons. Differences in catalytic efficiency result from distinct electronic densities of the pyridine ring, while embedding the catalytically active moiety into a polymeric structure has nearly no deleterious effect on the performance. © 2015 Society of Chemical Industry 相似文献
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Christian Gaber David Jocham Hannes Alois Weiss Ole Böttcher Wolfram Volk 《International Journal of Material Forming》2017,10(3):345-351
The prediction of formability is one of the most important tasks in sheet metal forming process simulation. The common criterion for ductile fracture in industrial applications is the Forming Limit Diagram (FLD). This is only applicable for linear strain paths. However, in most industrial simulation cases non-linear strain paths occur. To resolve this problem, a phenomenological approach is introduced, the so-called Generalized Forming Limit Concept (GFLC). The GFLC enables prediction of localized necking on arbitrary non-linear strain paths. Another possibility is the use of the Time Dependent Evaluation Method (TDEM) within the simulation as a failure criteria. During the Numisheet Benchmark 1 (2014) a two-stage forming process was performed with three typical sheet materials (AA5182, DP600 and TRIP 780) and three different blank shapes. The task was to determinate the point in time and space of local instability. Therefore the strain path for the point of maximum local thinning is evaluated. To predict the start of local necking the Generalized Forming Limit Concept (GFLC), the Time Dependent Evaluation Method (TDEM) and the modified TDEM were applied. The results of the simulation are compared with the results of the Benchmark experiment. 相似文献
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The author byline is an indispensable component of a scientific paper. Some journals have added contribution lists for each paper to provide detailed information of each author’s role. Many papers have explored, respectively, the byline and contribution lists. However, the relationship between the two remains unclear. We select three prominent general medical journals: Journal of the American Medical Association (JAMA), Annals of Internal Medicine (Annals), and PLOS Medicine (PLOS). We analyze the relationship between the author byline and contribution lists using four indexes. Four main findings emerged. First, the number, forms, and names of contribution lists significantly differed among the three journals, although they adopted the criteria of the International Committee of Medical Journal Editors. Second, a U-shaped relationship exists between the extent of contribution and author order: the participation levels in contribution lists were highest for first authors, followed by last and second authors, and then middle authors with the lowest levels. Third, regarding the consistency between author order in the contribution list and byline, every contribution category has a high consistency in JAMA and Annals, while PLOS shows a low consistency, in general. Fourth, the three journals have a similar distribution for the first authors in the contribution category; the first author in the byline contributes the highest proportion, followed by the middle and second authors, and then the last author with the lowest proportion. We also develop recommendations to modify academic and writing practice: implement structured cross-contribution lists, unify formats and standards of contribution lists, draft the author contribution criteria in the social sciences and humanities, and consider author contribution lists in scientific evaluation. 相似文献
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Quan-Bao Ma Jürgen Ziegler Bernhard Kaiser Dominic Fertig Wolfram Calvet Eswaran Murugasen Wolfram Jaegermann 《International Journal of Hydrogen Energy》2014
The electrochemical properties of single-crystalline p-type 3C-SiC films on p-Si substrate were investigated as an electrode in H2SO4 aqueous solutions in dark and under white light illumination. The photoelectrochemical (PEC) measurements indicates the p-type 3C-SiC film on p-Si substrate can generate a cathodic photocurrent as a photocathode, which corresponds to hydrogen production, and generate an anodic photocurrent as a photoanode, which corresponds to oxygen evolution. The surface chemical states of the films were investigated by XPS. In order to observe the surface chemical state changes after PEC test, the range of applied potential to the electrode was divided into three zones: −3.6 to 0 V, 0–1.5 V and 1.5–4 V vs. Ag/AgCl. After separated PEC tests in these three areas, XPS shows the surface of the SiC film in the range of −3.6 to 0 V and 0–1.5 V was stable without oxidation except the band bending occurred. But in the range of 1.5–4 V the film surface was oxidized due to anodic oxidation. 相似文献
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Wolfram Witte Daniel Abou‐Ras Karsten Albe Gottfried H. Bauer Frank Bertram Christian Boit Rudolf Brüggemann Jürgen Christen Jens Dietrich Axel Eicke Dimitrios Hariskos Matthias Maiberg Roland Mainz Max Meessen Mathias Müller Oliver Neumann Thomas Orgis Stefan Paetel Johan Pohl Humberto Rodriguez‐Alvarez Roland Scheer Hans‐Werner Schock Thomas Unold Alfons Weber Michael Powalla 《Progress in Photovoltaics: Research and Applications》2015,23(6):717-733
The gallium gradient in Cu(In,Ga)Se2 (CIGS) layers, which forms during the two industrially relevant deposition routes, the sequential and co‐evaporation processes, plays a key role in the device performance of CIGS thin‐film modules. In this contribution, we present a comprehensive study on the formation, nature, and consequences of gallium gradients in CIGS solar cells. The formation of gallium gradients is analyzed in real time during a rapid selenization process by in situ X‐ray measurements. In addition, the gallium grading of a CIGS layer grown with an in‐line co‐evaporation process is analyzed by means of depth profiling with mass spectrometry. This gallium gradient of a real solar cell served as input data for device simulations. Depth‐dependent occurrence of lateral inhomogeneities on the µm scale in CIGS deposited by the co‐evaporation process was investigated by highly spatially resolved luminescence measurements on etched CIGS samples, which revealed a dependence of the optical bandgap, the quasi‐Fermi level splitting, transition levels, and the vertical gallium gradient. Transmission electron microscopy analyses of CIGS cross‐sections point to a difference in gallium content in the near surface region of neighboring grains. Migration barriers for a copper‐vacancy‐mediated indium and gallium diffusion in CuInSe2 and CuGaSe2 were calculated using density functional theory. The migration barrier for the InCu antisite in CuGaSe2 is significantly lower compared with the GaCu antisite in CuInSe2, which is in accordance with the experimentally observed Ga gradients in CIGS layers grown by co‐evaporation and selenization processes. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献