1,721,060 research outputs found
Replication Data for: Single atom alloys 2.0: Exploiting undercoordination for stronger dissociative CH4 chemisorption
No full textA compressed archive containing all surface geometries of dissociative methane adsorption on the doped PGM(211) facets as CONTAR files for VASP
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Rate Data for "Water Gas Shift and Methane Steam Reforming Kinetics on Pt+PdAl2O3 Monolith"
No full textRate data for manuscript "Water Gas Shift and Methane Steam Reforming Kinetics on Pt+Pd/Al2O3 Monolit
Using predictive modeling to improve catalyst performance in low temperature diesel combustion
No full textDiesel engine emissions are a major cause of air pollution producing carbon monoxide (CO), hydrocarbons, nitrogen oxide molecules (NOx), and particulate matter (PM). Low temperature combustion engines offer a promising solution for reducing NOx and PM emissions, but in turn, the lower temperature interferes with the diesel oxidation catalyst (DOC) causing an increase in CO and hydrocarbon emissions. To combat this, the development of new catalysts is critical. Recent studies by Song et. all show that a Pd/Cu alloy could lead to inhibition-free low temperature oxidation reactions. By modifying a python modeling package, Surface EP, a number of variations of Pd/Cu surfaces can be predicted quickly and with relative accuracy. The program develops a three by three surface cell and can test for binding energies with Oxygen at the three possible site locations (Top, Bridge, and Hollow). These variations are then screened for the best possible matches. Further testing can then be conducted for additional binding energies in the oxidation reaction using Density Functional Theory (DFT) calculations.Chemical and Biomolecular Engineering, William A. Brookshire Department ofHonors Colleg
CO and NO Co-Oxidation in PdCu Catalysts
No full textNewly developed diesel engines operate at lower temperatures and can simultaneously reduce NOx, particulate matter, and fuel consumption. However, typical catalytic converters use platinum-palladium alloys, which aren't active enough to meet EPA emission regulations at low temperatures due to the inhibition caused by the competitive adsorption between CO and NO. Thus, excess fuel must be burned in the engine to increase the exhaust temperature before entering the DOC. Since CO binds to the active sites more strongly than NO, the Pt-Pd catalyst bed must also be long enough for sufficient NO conversion. Finding a catalyst that co-oxidizes CO and NO at low temperatures with minimal inhibition effects will maximize fuel economy and lower the required costly precious metal loading for the DOC. Using density functional theory (DFT) and descriptor-based microkinetic modeling, alloys of coinage metals (copper, gold, and silver) with at least one oxophilic component were identified as potential candidates. Further computational screening of Pd and Pt alloyed with Cu or Ag was used to determine PdCu alloys as the most promising for inhibition-free, low-temperature CO oxidation in the presence of NO. By flowing gasses through a bench-scale reactor, we evaluated the performance of the PdCu, PdPt, and PdCu+PdPt alloys. The findings indicate the PdCu catalyst has the potential to improve PdPt at reduced temperatures.Chemical and Biomolecular Engineering, William A. Brookshire Department ofHonors Colleg
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Exploring the Efficacy of Single-Atom Alloy Catalysts for the Haber-Bosch Process
No full textThe Haber-Bosch process is used for the production of ammonia from gaseous nitrogen and hydrogen through the reaction N2 + 3H2 → 2NH3. Ammonia is used in fertilizer and its production uses approximately 2% of the world’s energy. Our Goals. To break or circumvent the established BEP trendlines and design a novel catalyst that supersedes existing ones through density functional theory (DFT). To design an inexpensive single atom alloy that optimizes N2 dissociation. To quantify the improvement of these single atom alloys over Ru(0001) using microkinetic modeling (MKM). Conclusions. Mo-promoted Co(0001) single atom alloy catalysts show markedly improved performance over conventional ruthenium catalysts and the industrially-used iron catalysts. Single atom alloys can be used to break the BEP trendlines in a variety of catalysis applications, including the Haber-Bosch process. Microkinetic modeling is a powerful tool that can predict results for a wide variety of systems of reactions.Chemical and Biomolecular Engineering, William A. Brookshire Department ofHonors Colleg
Computational Study of CO2 Capture Using MIL-100 (Cr)
No full textMetal-organic frameworks (MOFs) are porous organometallic compounds that are of high interest to many researchers due to their capability to trap industrial greenhouse gases, such as CO2, that contribute to anthropogenic global warming. A promising MOF that has gained the attention of the research community in recent years is the CO2 adsorbent MIL-100 (Cr). This compound consists of Cr3-μ3-oxo clusters referred to as secondary building units (SBU) and organic linkers derived from trimesic acid. Thermally activated SBUs possess coordinatively unsaturated sites Cr sites – or open metal sites (OMS) – that possess oxidation states of +2 or +3. Previous experimental work indicated that CO2 molecules bind more strongly to +2 OMS than to +3 OMS at low adsorptive pressures. In this study, two central questions were addressed. Firstly, can the experimentally observed OMS selectivity be verified through density functional theory (DFT) simulations? Secondly, what electronic processes are responsible for OMS selectivity? DFT computations of the binding energy, enthalpy, and free energy of CO2 adsorption onto +2 and +3 OMS verify that CO2 exhibits a significantly greater affinity for the +2 OMS. Furthermore, a comparison of the adsorption charge transfer and optimized binding geometries reveal that this selectivity arises from the energetically favorable chemisorption of CO2 onto +2 OMS – relative to the weaker physisorption of the greenhouse gas onto +3 OMS. The novel methodology utilized for this study can be implemented in computational investigations of other MOFs that can be used for carbon capture applications.Chemical and Biomolecular Engineering, William A. Brookshire Department ofHonors Colleg
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