1,720,963 research outputs found
Electronic Structure of Rh and Ir Single Atom Catalysts Supported on Defective and Doped ZnO: Assessment of Their Activity Towards CO Oxidation
Full text linkThis study investigated the electronic structure of single-atom Rhodium (Rh) and Iridium (Ir) adsorbed on defective and impurity-doped ZnO(0001) surfaces, and assessed their activity towards the CO oxidation reaction. Our findings reveal that surface impurities significantly influence the binding energies and electronic properties of the metal atoms, with Al and Cr serving as particularly effective promoters. While Rh and Ir acquire a positive charge upon incorporation on the unpromoted Zn(0001) surface, adsorption directly on the promoter results in a net negative charge, thus facilitating the activation of both CO and O2 species. These results highlight the potential of impurity-promoted ZnO surfaces in modulating and tailoring the electronic properties of SACs, which can be used for a rational design of active single-atom catalysts
Çevresel uygulamalarla ilgili katalitik süreçlerin yoğunluk fonksiyoneli teorisi araştırma sı: metal oksitler ve eriyik metaller
No full textThis thesis investigates the catalytic activities of metal oxides and molten metals for cleaner environmental applications using density functional theory (DFT). The thesis focuses on two scopes: the catalytic performances of Rh- and Ir- enriched ZnO single-atom catalysts (SACs) in the presence of impurities and CH4 pyrolysis in BiNiX (X = Cu, Al) molten metal alloy catalysts. The first part investigates the catalytic activity of Rh- and Ir- ZnO surfaces. The SACs are analyzed in detail with CO, O2, and O adsorption, charge analysis, and vibrational frequencies. The study contains the effects of Al, Cr, Cu, and Pd impurities, providing insights into optimizing the activity of the catalysts. The second part examines the reactivity descriptors of metal alloys and the reactivity of molten metal catalysts, particularly BiNiX (X = Cu, Al) alloys, in methane pyrolysis, which offers a cleaner alternative to traditional hydrogen production methods without CO2 emissions. First, we present a thorough investigation of d-band center and Bader charges for various molten metal alloys in different concentrations and geometries. Next, we investigate the impact of a third component, Cu and Al as a promoter, on the reactivity of Bi-Ni molten alloys. We meticulously develop and present an ab initio molecular dynamics-based protocol to provide a deeper understanding of reaction mechanisms in molten metals. This study aims to enhance the understanding and development of efficient, sustainable catalysts by providing a first principles approach. The methods developed in this study might be used in future research to analyze a more comprehensive range of promoters, enabling the design of more effective energy production systems.Bu tezde, yoğunluk fonksiyoneli teorisini (YFT) kullanarak daha temiz çevre uygulamaları için metal oksitlerin ve erimiş metallerin katalitik aktiviteleri araştırılmıştır. Tezde temel olarak iki kapsama odaklanılmıştır: safsızlıkların varlığında Rh- ve Ir- ile zenginleştirilmiş ZnO tek atomlu katalizörlerin (TAKlar) katalitik performansları ve BiNiX (X = Cu, Al) erimiş metal alaşım katalizörlerinde CH4 pirolizi. İlk bölümde Rh- ve Ir- ZnO yüzeylerinin katalitik aktiviteleri araştırılmıştır. TAKlar CO, O2 ve O adsorpsiyonu, yük analizi ve titreşim frekansları ile ayrıntılı olarak analiz edilmiştir. Çalışma, katalizörlerin aktivitesini optimize etmeye yönelik içgörüler sağlayan Al, Cr, Cu ve Pd safsızlıklarının etkilerini de kapsamaktadır. İkinci bölümde, geleneksel hidrojen üretim yöntemlerine CO2 emisyonu olmadan daha temiz bir alternatif sunan metan pirolizinde erimiş alaşım katalizörlerinin, özellikle BiNiX (X = Cu, Al) alaşımlarının reaktivite tanımlayıcıları ve reaktiviteleri incelenmiştir. İlk olarak, farklı konsantrasyonlarda ve geometrilerde çeşitli yüzey alaşımları için d-bant merkezi ve Bader yüklerinin kapsamlı bir araştırması sunulmaktadır. Daha sonra, bir üçüncü bileşen olarak Cu ve Al metallerinin Bi-Ni erimiş alaşımlarının reaktivitesi üzerindeki etkisi çeşitli yöntemlerle araştırılmıştır. Erimiş metallerdeki reaksiyon mekanizmalarına dair daha derin bir anlayış sağlamak için ab initio moleküler dinamik simülasyonlarına dayalı bir protokol titizlikle geliştirilmiş ve sunulmuştur. Bu çalışmada, ilk prensipler yaklaşımını kullanarak verimli ve sürdürülebilir katalizörlerin anlaşılması ve geliştirilmesi amaçlanmaktadır. Bu çalışmada geliştirilen yöntemler, daha kapsamlı bir promotör yelpazesinin analiz edilmesinde gelecekteki araştırmalarda kullanılarak, daha etkili enerji üretim sistemlerinin tasarlanmasına olanak sağlayabilir.M.S. - Master of Scienc
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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