1,720,975 research outputs found
Hydrated and anhydrous molecular complexes of benzenepentacarboxylic acid and 4,4’-bipyridine
No full textSupramolecular assemblies of benzenepentacarboxylic acid (BPC) and 4,4’-bipyridine (bpy) as hepta- and di- hydrates in a 2:1 and 1:1 ratios of the respective co-crystal formers, as well as an anhydrous complex of 1:2 ratio have been reported. The three supramolecular complexes [(BPC-)2(bpy2+)(H2O)7], 1a, [(BPC-)(bpy+)(bpy)], 1b and [(BPC2-)(bpy2+)(H2O)2], 1c, were obtained by carrying out co-crystallization experiments at varied conditions. 1a and 1b were obtained at ambient and hydrothermal conditions, resepctively, while 1c also was obtained at hydrothermal conditions but only in the presence of Ni(NO3)2. All the molecular complexes were characterized by single-crystal X-ray diffraction method. Molecules in all the complexes are packed in the form of stacked layers with the realization of host-guest network in 1a and 1c along a crystallographic axis, wherein the host network is formed by BPC and water molecules through different types of hydrogen bonding patterns and bpy molecules remain as guests in the voids, while in 1b, a ladder type network is observed.</p
Supramolecular architecture in some 4-halophenylboronic acids
No full textCrystal structures of 4-chloro- and 4-bromophenylboronic acids (1 and 2) and hydrates of 2 and 4-iodophenylboronic acid in two different forms (2a, 3a, and 3b), which were characterized by single-crystal X-ray diffraction methods, are reported. In structures I and 2, -B(OH)2 forms a syn-anti conformation, but it exists in syn-syn as well as anti-anti conformations in the hydrated structures 2a, 3a, and 3b. In all the structures, the molecules are held together by O-H center dot center dot center dot O interactions formed by -B(OH)2 groups. The C-H center dot center dot center dot X (X = Cl, Br, and I) interactions play an important role in crystal packing. In 2, Br center dot center dot center dot Br interactions are also observed. Interestingly, all the three hydrates form similar types of three-dimensional structures with the formation of channels, which are occupied by water molecules. The two hydrates of 4-iodophenylboronic acid (3a and 3b) are distinguishable on the basis of O center dot center dot center dot O short contacts, with an identical host lattice of the boronic acid.</p
Novel Supramolecular Assemblies of Coordination Polymers of Zn(II) and Bis(4-nitrophenyl)phosphoric Acid with Some Aza-Donor Compounds
No full textSupramolecular assemblies of coordination polymers of Zn(II) and bis(4-nitrophenyl)phosphoric acid, BNPP, with aza-donor compounds, 4,4¢-bipyridine (bpy), 1,2-bis(4-pyridyl)ethane (bpyea), 1,2-bis(4-pyridyl)ethene (bpyee), and 1,3-bis(4-pyridyl)-propane (bpypa), have been reported. All the compounds are quite similar in the three-dimensional packing, irrespective of the varied dimensions of aza-donor molecules. All four compounds were synthesized by treating BNPP with corresponding aza-donor molecules in the presence of MeOH and water as the solvents. The structures were characterized by single-crystal X-ray diffraction.</p
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
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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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