1,721,044 research outputs found
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
Assembly of [Mn<sup>II</sup><sub>2</sub>Mn<sup>III</sup><sub>2</sub>] <i>S</i> = 9 Clusters via Azido Bridges: a New Single-Chain Magnet
No full textIn the present work, we report a new manganese single-chain magnet built from tetranuclear MnII2MnIII2 mixed-valence units linked by end-on azido and oximato bridges. All of the intra- and intercluster interactions involve end-on azido bridges, resulting in one ferromagnetic chain of ferromagnetic clusters with local ground state S = 9
Linked Nickel Metallacrowns from a Phosphonate/2-Pyridyloximate Blend of Ligands: Structure and Magnetic Properties
No full textIn
the present work, four new NiII clusters with nuclearities
ranging between Ni4 and Na2Ni8 were
synthesized, employing the versatile ligand phenylphosphonate and
6-methylpyridylaldoximate as the coligand. Crystallographic data show
that the tetranuclear complex [Ni4(6-MepaoH)4(PhPO3)2(OH)2(MeOH)4](OH)2 (1) consists of two dimers linked by phosphonate
bridges, whereas [Cs2Ni6(6-Mepao)6(PhPO3)3(OH)2(H2O)8] (2), Cs[Ni8(6-MepaoH)6(6-Mepao)6(PhPO3)3](ClO4)5 (3), and [Ni8Na2(BzO)6(6-Mepao)6(PhPO3)3] (4) are built from phosphonato-linked {Ni3(6-Mepao)3} metallacycles. The [9-MCNiII(6‑Mepao)-3] fragments in 2–4 show the unusual coordination of additional Cs+, Na+, and/or NiII cations. Direct-current
magnetic measurements were carried in the 300–2 K range. Analysis
of the experimental data revealed a complex response with strong antiferromagnetic
interactions mediated by the oximato bridges and weak interactions
mediated by the phosphonate ones
Anionic Guests in Prismatic Cavities Generated by Enneanuclear Nickel Metallacycles
No full textThe combination of polydentate aminated
ligands with the 2-pyridyloxime-nickel-azide
system leads to series of clusters with unprecedented topologies.
Among them, a remarkable family of {Ni9} metallacycles
that are capable of selective encapsulation of azide/halide anions
in a cryptand-like cavity through hydrogen-bond interactions has been
characterized
Ni<sub>5</sub>, Ni<sub>8</sub>, and Ni<sub>10</sub> Clusters with 2,6-Diacetylpyridine-dioxime as a Ligand
No full textIn the present work, novel coordination possibilities for the system dapdoH2/NiII (dapdoH2 = 2,6-diacetylpyridine-dioxime) have been explored. Depending on the starting reagents and solution conditions, several clusters with nuclearities ranging from Ni5 to Ni10 were achieved and structurally characterized, namely, [Ni5(R-COO)2(dapdo)2(dapdoH)2(N(CN)2)2(MeOH)2] in which R-COO– = benzoate (1) or 3-chlorobenzoate (2), [Ni8(dapdo)4(NO3)4(OH)4(MeOH)4] (3), and [Ni10(dapdo)8(N(CN)2)2(MeO)(MeOH)](NO3) (4). For the first time, pentadentate coordination for the dapdo2– ligand has been established. All compounds show a combination of square-planar and octahedrally coordinated nickel atoms. According to the Ni2(sp)Ni3(Oh) (1 and 2), Ni4(sp)Ni4(Oh) (3), and Ni4(sp)Ni6(Oh) (4) environments, these systems magnetically behave as trimer, tetramer, and hexanuclear clusters, respectively. dc magnetic measurements in the 2–300 K range of temperature reveal antiferromagnetic coupling for all compounds, and the correlation of the superexchange interaction with the torsion angles involving the oximato bridges is experimentally confirmed
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
Topological insights in polynuclear Ni/Na coordination clusters derived from a schiff base ligand
No full textThis article presents the syntheses, crystal structures, topological features and magnetic properties of two NiII/NaI coordination clusters (CCs) formulated [NiII3Na(L1)3(HL1 (MeOH)2] (1) and [NiII6Na(L1)5(CO3)(MeO (MeOH)3(H2O)3]·4(MeOH) 2(H2O) [2 4(MeOH) 2(H2O)] where H2L1 is the semi rigid Schiff base ligand (E)-2-(2-hydroxy-3 methoxybenzylideneamino)-phenol). Compound 1 possesses a rare NiII3NaI cubane (3M4-1) topology and compound 2 is the first example in polynuclear Ni/Na chemistry that exhibits a 2,3,4M7-1 topology
Ni<sub>5</sub>, Ni<sub>8</sub>, and Ni<sub>10</sub> Clusters with 2,6-Diacetylpyridine-dioxime as a Ligand
No full textIn the present work, novel coordination possibilities for the system dapdoH2/NiII (dapdoH2 = 2,6-diacetylpyridine-dioxime) have been explored. Depending on the starting reagents and solution conditions, several clusters with nuclearities ranging from Ni5 to Ni10 were achieved and structurally characterized, namely, [Ni5(R-COO)2(dapdo)2(dapdoH)2(N(CN)2)2(MeOH)2] in which R-COO– = benzoate (1) or 3-chlorobenzoate (2), [Ni8(dapdo)4(NO3)4(OH)4(MeOH)4] (3), and [Ni10(dapdo)8(N(CN)2)2(MeO)(MeOH)](NO3) (4). For the first time, pentadentate coordination for the dapdo2– ligand has been established. All compounds show a combination of square-planar and octahedrally coordinated nickel atoms. According to the Ni2(sp)Ni3(Oh) (1 and 2), Ni4(sp)Ni4(Oh) (3), and Ni4(sp)Ni6(Oh) (4) environments, these systems magnetically behave as trimer, tetramer, and hexanuclear clusters, respectively. dc magnetic measurements in the 2–300 K range of temperature reveal antiferromagnetic coupling for all compounds, and the correlation of the superexchange interaction with the torsion angles involving the oximato bridges is experimentally confirmed
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