1,720,985 research outputs found
H2[Pt(C2O4)2] as a Tailor-made Halide-free Precursor for the Preparation of Diesel Oxidation Catalysts: Nanoparticles Formation, Thermal Stability and Catalytic Performance
Full text linkThe aim of this study was to investigate a tailor-made metal precursor and its chemical properties to tune the properties of supported metal nanoparticles (NPs) and their catalytic performance when used as Diesel Oxidation Catalyst (DOC). The formation of extremely small Pt NPs from a new halide-free Pt complex was investigated, namely bis(oxalato)platinate, H-2[Pt(C2O4)(2)]. The size evolution of the supported NPs, from the formation upon the Pt precursor decomposition on gamma-alumina to the sintering of the NPs at high temperatures, was followed by thermogravimetric analysis coupled with mass spectrometry (TG-MS) and differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. A correlation between the NPs' size of the catalyst and the performance for the CO, C3H6, C3H8 and NO oxidation reactions pointed out a retained activity during test cycles, showing low sensitivity to the test conditions applied (i. e., temperature and gas composition). The overall catalytic performance was better in the fresh catalysts compared to the reference catalyst prepared from platinum nitrate, Pt(NO3)(4). In particular, the different dispersion of the Pt NPs over the support obtained from the two precursors was identified as the reason for the different catalytic performance, retaining small NPs size after the tests cycles
Reply to comment by E. Pollak on "Photoisomerization of trans-stilbene in moderately compressed gases: Pressure-dependent effective barriers" (J. Phys. Chem. A 1999, 103, 10528-10529)
No full text
Enabling micro-kinetics based simulation of industrial packed-bed reactors by physics-enhanced neural networks
Full text linkMultiscale CFD simulations can provide insights into the coupling of the surface catalytic mechanism and reactor scale transport phenomena. To address the high computational cost of detailed micro-kinetic models, we have applied for the first time artificial neural networks (NNs) as surrogate models for micro-kinetic rate evaluations, with the aim of accelerating particle-resolved CFD simulations of a catalytic reactor. To evaluate the efficacy of the proposed strategy, a methane steam reforming packed bed reactor was selected as a benchmark case. A global reaction neural network with embedded thermodynamic and stoichiometric information has been implemented as a surrogate for a UBI-QEP micro-kinetic model available in literature. Two distinct test cases have been employed. The first targets a lab scale reactor, enabling either the full evaluation of the micro-kinetic scheme or the novel NN accelerated approach in the CFD simulations. The comparison between the two strategies showed deviations in the computed mole fractions of less than 1 % across a wide range of operating conditions along with a 19-fold total simulation and 63-fold chemistry speed-up. Consequently, the total simulation time of the benchmark was reduced from 114 h to 6 h, with only 29.2 % or 1.75 h of the computational cost being allocated to the chemistry sub-step of the solver. Therefore, source term evaluations are no longer the bottleneck of reactive CFD. Given the obtained excellent accuracy and speed-up, we applied the NN-accelerated micro-kinetics to the CFD simulation of an industrial scale packed-bed reactor, discretized with 44 M cells (54 % solid phase). To the best of our knowledge, this represents the largest reactive simulation with micro-kinetic level of detail. Overall, these results pave the way for the scale-up of multiscale simulations to industrially relevant scales
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Variations on the Author
Full text link“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
Full text linkWe 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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