1,720,958 research outputs found
Tuning Gaps and Schottky Contacts of Graphene/Phosphorene Heterostructures by Vertical Electric Field and Strain
Full text linkWe present a comprehensive study of the structural and electronic properties of a graphene/
phosphorene (G/P) heterostructure in the framework of density functional theory, including van der
Waals interaction in the exchange–correlation functional. While the G(4 1)/P(3 1) superlattice
usually used in the literature is subject to a strain as high as about 7%, the in-plane strain could
be drastically reduced to under 1% in the G(4 13)/P(3 12) heterostructure investigated here.
Adapting the lattice constants of the rectangular lattices, the equilibrium configuration in the xy
plane of phosphorene relative to the graphene layer is optimized. This results in an equilibrium
interlayer distance of 3.5 Å and a binding energy per carbon atom of 37 meV, confirming the presence
of weak van der Waals interaction between the graphene and the phosphorene layers. The electronic
properties of the heterostructure are evaluated under different values of interlayer distance, strain
and applied vertical electric field. We demonstrate that G/P heterostructures form an n-type Schottky
contact, which can be transformed into p-type under external perturbations. These findings, together
with the possibility to control the gaps and barrier heights, suggest that G/P heterostructures are
promising for novel applications in electronics and may open a new avenue for the realization of
innovative optoelectronic devices
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
Tailoring the electronic properties of graphene-based 2D materials via heterostructures engineering
Full text linkSince the discovery of graphene in 2004, both theoretical and experimental research on 2D materials has experienced exponential growth that continues to this day. The exceptional electronic, thermal, and mechanical properties, as well as a plethora of exotic physical phenomena that can originate from them, are the main reasons for the great interest that low-dimensional systems have garnered from the beginning. One of the main advantages of 2D materials is the ability to stack them more or less arbitrarily to form heterostructures in which the planes are linked by weak Van der Waals interactions. In this way, innovative heterostructures can be created, without a bulk counterpart, with different properties compared to the individual layers that compose them. Thanks to their versatility, it is possible to create new materials with on-demand properties based on the required application. In this sense, it is of fundamental importance to have theoretical tools to design these systems, being able to calculate with appropriate precision their stability, formation thermodynamics, and electronic properties, and many other aspects. In this doctoral thesis, various Van der Waals heterostructures have been studied using ab-initio methods, with the aim of understanding how to finely modify their electronic properties by altering their geometry and composition. This research focuses on both the study of graphene/hBN heterostructures and the thermodynamics of formation of non graphene-based 2D systems, such as plumbene and pnictogens
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
Thermodynamics and electronic structure of adsorbed and intercalated plumbene in graphene/hexagonal SiC heterostructures
Full text linkAbstract Graphene-covered hexagonal SiC substrates have been frequently discussed to be appropriate starting points for epitaxial overlayers of Xenes, such as plumbene, or even their deposition as intercalates between graphene and SiC. Here, we investigate, within density functional theory, the plumbene deposition for various layer orderings and substrate terminations. By means of total energy studies we demonstrate the favorization of the intercalation versus the epitaxy for both C-terminated and Si-terminated 4H-SiC substrates. These results are explained in terms of chemical bonding and by means of layer-resolved projected band structures. Our results are compared with available experimental findings
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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