1,721,025 research outputs found
Syn–anti conformation switching of a bis-porphyrin derivative at the air–water interface and in the solid state as an effective tool for chemical sensing
No full textA Langmuir film of bis(zinc octaethylporphyrin) (ZnPP) was characterised at the air–water interface and its
syn–anti conformation switching induced upon addition of aromatic amines was studied by infrared and
UV–vis reflection spectroscopic methods. The highly specific interaction of ZnPP with aromatic amines
was maintained even after the floating film was transferred onto solid supports by the Langmuir–
Schaefer (LS) technique, enabling us to selectively sense aromatic amines at concentrations as low as
20 ppb. Furthermore, LS ZnPP active layer selectivity was evaluated in the presence of aliphatic amines
Langmuir-Schaefer Films of a bis-Zn Porphyrin: Spectroscopic investigations of Molecular Organization and Activity inside Multilayers
No full text
Spectroscopical, Photochemical and Morphological Studies of Bis Zn-Ethane-Bridged Porphyrins Dimer Langmuir-Schaefer Films
No full textLangmuir-Schäfer films of an ethane-bridged bis(Zn porphyrin): spectroscopic evidences of molecular organization and activity inside multilayers
No full textGoing 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
Molecular Organisation and syn-anti Conformational Equilibria in Ethane-Bridged Bis(ZincPorphyrin) Floating Films at the Air-Water Interface
Full text linkThe behavior of the symmetrical ethane-bridged bis(Zn porphyrin) (1) has been investigated at the air–water interface.
The molecular organization of floating films of pure 1 and its mixture with amphiphilic substances, such as arachidic
acid and n-octadecylamine, was inspected by means of surface pressure–area isotherms, Brewster angle microscopy
and reflection spectroscopy in the UV–Vis region. The overall results suggest the presence in all cases of mainly the anti
conformer of 1 even when the dimer was spread on pure water, through the ligation of water molecules to the zinc
atoms in the axial positions. It was also demonstrated for the first time that the syn-to-anti conformational transition
of the porphyrin dimer can be accelerated by the ligation of suitable amphiphiles even at the liquid-air interface. In
particular, it is noted that n-octadecylamine, and arachidic acid (to a lesser extent), added to the system as amphiphiles,
drive the syn«anti equilibrium of 1 towards the anti form through the axial ligation of the amino or carboxylate group
to the zinc atoms
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
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