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Microwave Applications in Radiolabelling with Short‐Lived Positron‐Emitting Radionuclides
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Rapid microwave-assisted cleavage of methyl phenyl ethers: new method for synthesizing desmethyl precursors and for removing protecting groups
No full textSummary A new microwave-enhanced method for rapid demethylation of methyl phenyl ethers using neat methanesulfonic acid (CH 3 SO 3 H) is presented. Using a monomodal microwave cavity, cleavage of anisole (1), used as model compound, to phenol (2) was achieved with high conversions (ca 80%) in very short reaction times (10-20 s). The feasibility of cleaving one or both of two methoxy groups was illustrated with 4-(3-bromoanilino)-6,7-dimethoxyquinazoline (PD153035, 3). High conversions (582%) of 3 were attained with four different conditions (i.e. combination of input effect (35-125 W) and time (15 s-2 min)). 4-(3-Bromoanilino)-7-hydroxy-6-methoxyquinazoline (4), 4-(3-bromoanilino)-6-hydroxy-7-methoxyquinazoline (5) and 4-(3-bromoanilino)-6,7-dihydroxyquinazoline (6), the possible mono-or di-demethylated compounds, were obtained. Methods for rapid demethylations are of interest in radiochemistry for post-labeling deprotections of hydroxyl containing aromatic rings and also provide a more direct route for synthesizing precursor compounds for labeling by alkylation
F‐labelled alkylating agent 2,2,2‐trifluoroethyl triflate: Synthesis and specific activity
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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
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