We report a new Ce-rich family of active oxygen evolution reaction (OER) catalysts composed of earth abundant elements, discovered using high-throughput methods.

Executive summary\n● Target audience: AmeriFlux community, AmeriFlux Science Steering Committee & Department of Energy (DOE) program managers [ARM/ASR (atmosphere), TES (surface), and SBR (subsurface)]\n● Problem statement: The atmospheric boundary layer mediates the exchange of energy and matter between the land surface and the free troposphere integrating a range of physical, chemical, and biological processes. However, continuous atmospheric boundary layer observations at AmeriFlux sites are still scarce. How can adding measurements of the atmospheric boundary layer enhance the scientific value of the AmeriFlux network?\n● Research opportunities: We highlight four key opportunities to integrate tower-based flux measurements with continuous, long-term atmospheric boundary layer measurements: (1) to interpret surface flux and atmospheric boundary layer exchange dynamics at flux tower sites, (2) to support regionalscale modeling and upscaling of surface fluxes to continental scales, (3) to validate land-atmosphere coupling in Earth system models, and (4) to support flux footprint modelling, the interpretation of surface fluxes in heterogeneous terrain, and quality control of eddy covariance flux measurements.\n● Recommended actions: Adding a suite of atmospheric boundary layer measurements to eddy covariance flux tower sites would allow the Earth science community to address new emerging research questions, to better interpret ongoing flux tower measurements, and would present novel opportunities for collaboration between AmeriFlux scientists and atmospheric and remote sensing scientists. We therefore recommend that (1) a set of instrumentation for continuous atmospheric boundary layer observations be added to a subset of AmeriFlux sites spanning a range of ecosystem types and climate zones, that (2) funding agencies (e.g., Department of Energy, NASA) solicit research on land-atmosphere processes where the benefits of fully integrated atmospheric boundary layer observations can add value to key scientific questions, and that (3) the AmeriFlux Management Project acquires loaner instrumentation for atmospheric boundary layer observations for use in experiments and short-term duration campaigns.

Abstract A highly efficient solid‐base organocatalyst for the gas‐phase aldol self‐condensation of n ‐butanal to 2‐ethylhexenal was developed by grafting site‐isolated amines on tailored silica surfaces. The catalytic activity depends largely on the nature of amine species, the surface concentration of amine and silanol groups, and the spatial separation between the silanol and amine groups. In situ FTIR measurements demonstrated that the formation of nucleophilic enamines leads to the enhanced catalytic activity of secondary amine catalysts, whereas the formation of imines (stable up to 473 K) leads to the low activity observed for silica‐supported primary amines. Blocking the silanol groups on the silica support by silylation or cofeeding water into the reaction stream drastically decreased the reaction rates, demonstrating that weaker acidic silanol groups participate cooperatively with the amine groups to catalyze the condensation reaction. This work demonstrates that the spatial separation of the weakly acidic silanols and amines can be tuned by the controlled dehydration of the supporting silica and by varying the linker length of the amine organosilane precursor used to graft the amine to the support surface. A mechanism for aldol condensation was proposed and then analyzed by DFT calculations. DFT analysis of the reaction pathway suggested that the rate‐limiting step in aldol condensation is carboncarbon bond formation, which is consistent with the observed kinetics. The calculated apparent activation barrier agrees reasonably with that measured experimentally.

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

Glucose–fructose isomerization mediated by Sn-BEA is investigated using an extended QM/MM model containing 208 tetrahedral atoms. The isomerization mechanism consists of a sequence of ring-opening, isomerization, and ring-closing processes, consistent with the previously reported experimental observations. In agreement with the experimentally observed kinetic isotope effect, the rate-determining step is found to involve a hydride shift from the C2 carbon to the C1 carbon. The apparent activation energy for the rate-limiting step is 22.3 kcal/mol at 343 K. The difference in the reaction barriers for the partially hydrolyzed and the fully coordinated Sn sites was investigated using energy decomposition analysis. It is found that the higher activity of the partially hydrolyzed site comes from the extra flexibility provided by the defect in the lattice. The effect of substituting Sn in the active site by Ti, Zr, V, Nb, Si, and Ge was examined, and it was found that Sn and Zr are metals that result in the lowest reaction barrier for glucose isomerization. By using energy decomposition analysis, two physical properties are shown to contribute to the magnitude of the reaction barrier: the polarizability of the metal atom in the active site and the Brønsted basicity of the oxygen atom bound to the metal atom.

The energy delivered to the land surface via insolation is a primary driver of evapotranspiration (ET)—the exchange of water vapor between the land and atmosphere. Spatially distributed ET products are in great demand in the water resource management community for real-time operations and sustainable water use planning. The accuracy and deliverability of these products are determined in part by the characteristics and quality of the insolation data sources used as input to the ET models. This paper investigates the practical utility of three different insolation datasets within the context of a satellite-based remote sensing framework for mapping ET at high spatiotemporal resolution, in an application over the Sacramento–San Joaquin Delta region in California. The datasets tested included one reanalysis product: The Climate System Forecast Reanalysis (CFSR) at 0.25° spatial resolution, and two remote sensing insolation products generated with geostationary satellite imagery: a product for the continental United States at 0.2°, developed by the University of Wisconsin Space Sciences and Engineering Center (SSEC) and a coarser resolution (1°) global Clouds and the Earth’s Radiant Energy System (CERES) product. The three insolation data sources were compared to pyranometer data collected at flux towers within the Delta region to establish relative accuracy. The satellite products significantly outperformed CFSR, with root-mean square errors (RMSE) of 2.7, 1.5, and 1.4 MJ·m−2·d−1 for CFSR, CERES, and SSEC, respectively, at daily timesteps. The satellite-based products provided more accurate estimates of cloud occurrence and radiation transmission, while the reanalysis tended to underestimate solar radiation under cloudy-sky conditions. However, this difference in insolation performance did not translate into comparable improvement in the ET retrieval accuracy, where the RMSE in daily ET was 0.98 and 0.94 mm d−1 using the CFSR and SSEC insolation data sources, respectively, for all the flux sites combined. The lack of a notable impact on the aggregate ET performance may be due in part to the predominantly clear-sky conditions prevalent in central California, under which the reanalysis and satellite-based insolation data sources have comparable accuracy. While satellite-based insolation data could improve ET retrieval in more humid regions with greater cloud-cover frequency, over the California Delta and climatologically similar regions in the western U.S., the CFSR data may suffice for real-time ET modeling efforts.

Abstract We propose a new method of chiral separation using functionalized nanoporous graphene as an example. Computational simulations based on density functional theory show that the attachment of a suitable chiral “bouncer” molecule to the pore rim prevents the passage of the undesired enantiomer while letting its mirror image through.

The CO + H/sub 2/ reaction was studied. Infrared spectra indicate that under reaction conditions, the catalyst surface is saturated with CO. Conversion of CO to CH/sub 4/ depends on the H/sub 2//CO ratio. The Ru surface is covered by CO, and in order for CH/sub 4/ to form, H/sub 2/ must compete for the remaining unoccupied sites. CH/sub 4/ and C/sub 2/H/sub 6/ probably arises through a common precursor, e.g., an Ru-CH groups, and C/sub 2/H/sub 6/ might occur through dimerization of Ru-CH groups. 6 figs. (DLC)