Reducible transition metal oxides (RTMOs) comprise an important class of catalytic materials that are used for the selective oxidation and electro- and photochemical splitting of water, and as supports for metal nanoparticles. It is, therefore, highly desirable to model the properties of these materials accurately using density functional theory (DFT) in order to understand how oxide structure and performance are related and to guide the search for materials exhibiting superior performance. Unfortunately, accurate description of the structural and electronic properties of RTMOs using DFT has proven particularly challenging. The M06-L density functional, which has been shown to be broadly accurate for calculations of gas phase clusters, has recently become available to researchers carrying out calculations in the solid state, but its performance in determining the properties RTMOs has been little investigated. The aim of this work was to assess the performance of the M06-L functional for describing the structural and electronic properties of a family of RTMOs: MoO<sub>2</sub>, MoO<sub>3</sub>, and Bi<sub>2</sub>Mo<sub>3</sub>O<sub>12</sub>. Lattice constants, band gaps, and densities of states calculated using the M06-L functional are compared to those obtained from DFT+U. We have also used the M06-L functional to determine the reaction barrier for propene activation over Bi<sub>2</sub>Mo<sub>3</sub>O<sub>12</sub>, the rate-limiting step in the oxidation of propene to acrolein. We find that while DFT calculations carried out with the M06-L functional are roughly five times more expensive computationally than those performed with DFT+U, the results obtained using the M06-L functional provide sensible results for all properties investigated, while avoiding the necessary trade-off between accurate electronic structure and accurate thermochemistry that occurs in DFT+U.

The objectives of this project have been twofold: (1) to develop a theoretical model for designing bubble-column reactors and assessing their performance and (2) to characterize the performance of a laboratory-scale bubble-column reactor. The theoretical part of the project has focused the effects of gas-liquid mass transfer; axial dispersion of gas, liquid, and catalyst; ad the interplay between the kinetics of Fischer-Tropsch synthesis and the water-gas-shift reaction. The experimental portion of the project has focused the effects of reaction conditions on product distribution and, in particular, the conditions under which gas-liquid mass transfer becomes important. Any independent set of experiments was undertaken to investigate the chemistry of carbonaceous deposits formed during Fischer-Tropsch synthesis. 8 refs.

Monomolecular reactions of alkanes in H-MFI were investigated by means of a dispersion-corrected density functional, ωB97X-D, combined with a hybrid quantum mechanics/molecular mechanics (QM/MM) method applied to a cluster model of the zeolite. The cluster contains 437 tetrahedral (T) atoms, within which a T5 region containing the acid site along with the representative alkane is treated quantum mechanically. The influence of active site location on reaction energetics was examined by studying cracking and dehydrogenation reactions of n-butane at two regions in H-MFI–T12, where the proton is at the intersection of straight and sinusoidal channels, and T10, where the proton is within the sinusoidal channel. Two transition states were observed for cracking: one where the proton attacks the C–C bond and another where it attacks a C atom. Dehydrogenation proceeds via a concerted mechanism, where the transition state indicates simultaneous H2 formation and proton migration to the framework. Intrinsic activation energies can be determined accurately with this method, although heats of adsorption were found to be higher in magnitude relative to experiments, which is most likely mainly caused by the MM dispersion parameters for the zeolite framework atoms. Intrinsic activation energies calculated for reactions at the T10 site are higher than those at T12 owing to differences in interaction of the substrate with the acid site as well as with the zeolite framework, demonstrating that Brønsted acid sites in H-MFI are not equivalent for these reactions. Apparent activation energies, determined from calculated intrinsic activation energies and experimentally measured heats of adsorption taken from the literature, are in excellent agreement with experimental results.

Earth and Space Science Open Archive posterOpen AccessYou are viewing the latest version by default [v1]Evaluating a UAV-based mobile sensing system designed to quantify ecosystem-based methaneAuthorsDerekHollenbeckiDKristenManiesiDYangQuanCheniDDennisBaldocchiEugenieEuskircheniDLanceChristensenSee all authors Derek HollenbeckiDCorresponding Author• Submitting AuthorUniversity of California MercediDhttps://orcid.org/0000-0002-4782-1370view email addressThe email was not providedcopy email addressKristen ManiesiDGeology, Minerals, Energy, and Geophysics Science CenteriDhttps://orcid.org/0000-0003-4941-9657view email addressThe email was not providedcopy email addressYangQuan CheniDUniversity of California MercediDhttps://orcid.org/0000-0002-7422-5988view email addressThe email was not providedcopy email addressDennis BaldocchiUniversity of California Berkeleyview email addressThe email was not providedcopy email addressEugenie EuskircheniDUniversity of Alaska FairbanksiDhttps://orcid.org/0000-0002-0848-4295view email addressThe email was not providedcopy email addressLance ChristensenNASA Jet Propulsion Laboratoryview email addressThe email was not providedcopy email address

The objective of the present study was to develop a heterogeneous catalyst for the hydrogenation of butanal that could function in the presence of CO and propene and, hence, could be used in a tandem reactor to enable the gas-phase conversion of propene and synthesis gas to butanol. To this end, we investigated the activity of silica-supported Shvo's catalyst (Shvo/SiO2) for the gas-phase hydrogenation of butanal. Experiments were performed to determine the kinetics of n- and iso-butanal hydrogenation. The apparent activation energies and the apparent partial pressure dependencies of n- and iso-butanal, H 2, and CO on the rates of n- and iso-butanol formation were determined. A mechanism for butanal hydrogenation was proposed to rationalize the observed kinetics and some of the reaction intermediates were observed by in situ infrared and 31P MAS NMR spectroscopy. It was found that Shvo/SiO2 was inhibited by SX (SX = sulfoxanthphos) and CO, and is inactive for alkene hydrogenation. The tandem catalytic conversion of propene and synthesis gas to butanol was then carried out using a SX-Rh supported ionic liquid phase (SILP) catalyst to promote the hydroformylation of propene to butanal and Shvo/SiO2 to promote the hydrogenation of butanal to butanol. The rate expressions describing the kinetics of each of the catalysts were then used to predict operating conditions required to achieve high conversion of propene to butanol. Under the most favorable conditions examined (H2/CO = 10), an overall yield of 13% to butanol was achieved with 15% propene conversion and 90% aldehyde conversion at a temperature of 413 K. © 2013 Elsevier Inc. All rights reserved.

This is the FLUXNET-CH4 version of the carbon flux data for the site US-Tw3 Twitchell Alfalfa.

Abstract Reliable partitioning of micrometeorologically measured evapotranspiration (ET) into evaporation ( E ) and transpiration ( T ) would greatly enhance our understanding of the water cycle and its response to climate change related shifts in local‐to‐regional climate conditions and rising global levels of vapor pressure deficit (VPD). While some methods on ET partitioning have been developed, their underlying assumptions make them difficult to apply more generally, especially in sites with large contributions of E . Here, we report a novel ET partitioning method using artificial neural networks (ANNs) in combination with a range of environmental input variables to predict daytime E from nighttime ET measurements. The study uses eddy covariance data from four restored wetlands in the Sacramento‐San Joaquin Delta, California, USA, as well as leaf‐level T data for validation. The four wetlands vary in their vegetation make‐up and structure, representing a range of ET conditions. The ANNs were built with increasing complexity by adding the input variable that resulted in the next highest average value of model testing R 2 across all sites. The order of variable inclusion (and importance) was: VPD > gap‐filled sensible heat flux ( H _gf) > air temperature ( T air ) > friction velocity ( u ∗ ) > other variables. The model using VPD, H _gf, T air , and u ∗ showed the best performance during validation with independent data and had a mean testing R 2 value of 0.853 (averaged across all sites, range from 0.728 to 0.910). In comparison to other methods, our ANN method generated T /ET partitioning results which were more consistent with CO 2 exchange data especially for more heterogeneous sites with large E contributions. Our method improves the understanding of T /ET partitioning. While it may be particularly suited to flooded ecosystems, it can also improve T /ET partitioning in other systems, increasing our knowledge of the global water cycle and ecosystem functioning.

Abstract Ein neuartiges, auf funktionalisiertem, nanoporösen Graphen basierendes Verfahren zur Abtrennung chiraler Moleküle wird vorgestellt. Auf Dichtefunktionaltheorie basierende Computersimulationen zeigen, dass durch Anhaften eines chiralen “Türsteher”‐Moleküls an den Porenrand einer Form des Enantiomers der Eintritt verweigert wird, während sein Spiegelbild passieren kann.

Abstract A series of alkali metal or alkaline earth‐exchanged NiX (X=faujasite zeolite, Si/Al=1.2) zeolites containing approximately 0.6 wt % Ni as Ni 2+ cations were examined as catalysts for propene oligomerization at 453 K and 5 bar (500 kPa). In the presence of propene, the activity of alkali metal‐exchanged zeolites (NiLiX, NiNaX, and NiKX) increased with time on stream, reached a maximum, then decreased, and finally reached steady state. In contrast, the activity of alkaline earth‐exchanged zeolites (NiMgX, NiCaX, and NiSrX) was high initially and then decreased until steady‐state activity was achieved. The primary product formed in all cases was hexene (90 %), and nonene was the only other product observed (10 %). Both the rate of propene dimerization and the ratio of branched to linear hexene isomers were determined to depend on the identity of the charge‐compensating cation, with the dimerization rate and degree of dimer branching increasing with increasing free volume in the zeolite supercages. The apparent activation energy for trimer formation was greater than that for dimer formation, which suggests that steric constraints imposed by the zeolite may inhibit the growth of larger oligomers.

This is the AmeriFlux version of the carbon flux data for the site US-Snf Sherman Barn. Site Description - The Sherman Barn is pasture site on Sherman Island, that is managed by the California Department of Water Resources (DWR). A flux tower equipped to analyze energy, H2O, CO2, and CH4 fluxes was installed on June, 2018

Resonant inelastic X-ray scattering and high-resolution X-ray absorption spectroscopy were used to identify the chemical state of a Co electrocatalyst in situ during the oxygen evolution reaction. After anodic electrodeposition onto Au(111) from a Co(2+)-containing electrolyte, the chemical environment of Co can be identified to be almost identical to CoOOH. With increasing potentials, a subtle increase of the Co oxidation state is observed, indicating a non-stoichiometric composition of the working OER catalyst containing a small fraction of Co(4+) sites. In order to confirm this interpretation, we used density functional theory with a Hubbard-U correction approach to compute X-ray absorption spectra of model compounds, which agree well with the experimental spectra. In situ monitoring of catalyst local structure and bonding is essential in the development of structure-activity relationships that can guide the discovery of efficient and earth abundant water splitting catalysts.

Methane, ethane, propane, and n-butane were polymerized in a plasma created by a radio-frequency glow discharge. It was found that the kinetics of polymer deposition were similar for all monomers but methane. It is suggested that the deviation from "normal" behavior of methane may be due to the difference in mechanism of formation of reaction intermediates. The "characteristic map" for the plasma polymerization of ethane was determined. It was shown that, in addition to transparent films, powders may be formed at low pressures and low monomer flow rates and unstable discharges at high pressures and low flow rates. With increasing power input, the unstable regions are decreased while the powdery regions are increased. The rates of polymer deposition were found to depend on pressure, flow rate, and power. An empirical equation is proposed that relates the rates of deposition for ethane, propane, and n-butane to these parameters.

These datasets are supplementary to the paper "<strong>Representativeness of Eddy-Covariance Flux Footprints for Areas Surrounding AmeriFlux Sites</strong>" by Chu et al. Dataset S1. Summary of site-specific footprint metrics filename: All_site_fpt_summary.csv readme: All_site_fpt_summary-README.csv Dataset S2. All monthly footprint climatology weight maps filename: monthly_footprint_climatology_weight_map.zip the zip folder contains individual files of all monthly footprint weight maps filename: &lt;Site-ID&gt;_&lt;Year&gt;_&lt;Month&gt;_&lt;DAY/NIGHT&gt;_fpt_weight.tif readme: README.txt Dataset S3. All site-year footprint climatology overlapped with true-color satellite images. filename: site-year_footprint_climatology_realcolor_map.zip the zip folder contains individual files of footprint climatologies from all site-years filename: &lt;Site-ID&gt;_&lt;Year&gt;_&lt;Spatial_Extent&gt;_shrink_footprint_climatology.png readme: README.txt Dataset S4. Site-specific results and representativeness index based on the land cover type analysis. filename: All_site_land_cover_dominant_summary2.csv readme:All_site_land_cover_dominant_summary2-README.csv Dataset S5. Site-specific results and representativeness index based on the EVI analysis. filename: All_site_Landsat_EVI_fpt_comparison2.csv readme: All_site_Landsat_EVI_fpt_comparison2-README.csv Dataset S6. All available site-month EVI and time-explicit representativeness. filename: All_site_Landsat_EVI_all_cutout2.csv readme: All_site_Landsat_EVI_all_cutout2-README.csv