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Triel, tetrel, pnicogen, chalcogen, halogen, aerogen bonds : non-covalent interactions of P block elements
No full textIt is widely accepted that hydrogen bonds contribute into a variety
of meaningful processes in nature and human body which has reflection in the
share of the scientific community attention over the last decades. Recent
years have seen a veritable explosion of research into noncovalent interactions that
are analogous to the commonly acknowledged H-bonds. It became obvious that
detailed investigation of these types of short contacts should be extensively
considered as the main target for theoretical chemistry. In 2007 the article described
the σ-hole concept enlightened the phenomena of the halogen bond. Later
extensions of this concept into the other elements in periodic table provided the
necessary knowledge about the origin of these interactions and gave arise for
introducing the other members of the σ-hole bonds family as the chalcogen,
pnicogen, tetrel and triel bonds or even those involving noble gases.
The foundation of the σ-hole theory is the presence of the region of thinned
electronic density caused by the anisotropic accumulation of the negative charge on
the covalent R-X bond (where X=halogen) what causes the rising of positive
electrostatic potential on the outer side of X atom. This particular location becomes
the binding site for the approaching nucleophile. As the σ-hole is located in plane
of molecule on an extension of covalent bond, some molecules also contain
a σ-hole region situated above and below the plane of the molecular framework.
In current work the representative examples of complexes bonded through the
σ- or π-holes and their most important features have been briefly given. The main
goal was to show the diversity of this type of interaction which covers nearly all the
elements of the block p of periodic table.
Triel bonds are produced mainly by -hole interaction with Lewis bases and
can be characterized by different nature for different elements (boron complexes are
stabilized by electrostatics and charge transfer, while Al and Ga ones mostly by
electrostatics).
In tetrel, pnicogen and chalcogen bonded complexes it has been shown that
during the process of dimerization the substantial geometric distortion is observed
on the -hole donor molecules. It causes the creation of the second complexation
path through newly created -hole. In chalcogen bonded complexes the
alternative dimer is stabilized by π-hole and something like - due
to presence of lone electron pair of chalcogen.
Within the halogen bonds one can highlight the issue of weakening the
negative hyperconjugation on the molecules of methylated derivatives of ammonia
(like methylamine). It is caused by the appearing of σ-hole donor (FCCl3) which
takes control of the majority part of intramolecular charge transfer and in this way
enhances the link between subunits at the price of hampering the internal
conjugation.
Finally, the short report of aerogen bonds in literature is inserted in the last
chapter of current paper. Some molecules with noble gases connected with highly
electron-withdrawing constituents are able to generate both: σ- and π-hole on their
surfaces and in consequences the stable complexes with Lewis bases (for example,
diazines). The presence of the latter proves that the discussed types of interaction
are very common for massive amount of atoms, even for those which are
considered as less reactive
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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