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Structural Analysis by Powder Diffraction Methods
No full textHere we provide some basic information about the importance, the procedure and the accuracy of structural powder diffraction methods, with particular emphasis on small molecules crystallography, drug development and polymorphic characterization
Reversibly changing a painkiller structure: A hot topic for a cold case-Ibuprofen lysine salt
No full textIbuprofen lysine salt can undergo a fully reversible, thermally induced phase transition into a different enantiotropically related polymorphic form. The structures of both the high and low temperature phases were solved using state-of-the-art X-ray powder diffraction methods, showing many similarities both in the molecular conformation and in the crystal packing. The full structural analysis and comparison of the two crystal structures allowed to understand the mechanism of the phase transition and explain its reversible nature in what appears to be a rare case of isosymmetric temperature-driven phase transformation of an organic solid
A structural powder diffraction study of two polymorphic forms of nortriptyline hydrochloride
No full textPersistency of a two-fold embrace in crystalline phases of Bupropion hydrohalides: a thorough ab-initio X-ray powder diffraction study
No full textBupropion hydrohalide salts yield ten different crystal phases of bupropion (four hydrochloride, two hydrobromide, and four hydroiodide salts). Of these forms, only four have been previously characterized by single crystal or powder diffraction analysis. The structures of the six new crystal forms have been solved using state-of-the art structural powder diffraction methods. All ten phases have been found to be made up of the same supramolecular synthon packed in different ways. The supramolecular synthon common to all phases is a bupropion hydrohalide dimer held together by hydrogen bonding. The true driving force of the polymorphism of bupropion hydrohalides is therefore the ability of the bupropion hydrohalide dimer to pack in several different ways and not the ability of the molecule to form different hydrogen bonding motifs or to exist with aliphatic branches in different stable conformations
Azelastine Hydrochloride: A Powder Diffraction and 13C CPMAS NMR Study of Its Anhydrous and Solvated Forms
No full text
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
Salt or Cocrystal? Using XRPD to Infer Proton Transfer in Three Adducts of Iodoxybenzoic Acid by Analyzing Iodine–Oxygen Bond Lengths
No full text2-Iodoxybenzoic acid (IBX) is a versatile oxidant, which
has been
used for a plethora of reactions through the years. Its explosive
properties and low solubility, the major limitations to a more widespread
use of this reactant, have led to the search for derivatives, adducts,
or mixtures with comparable oxidative properties but better characteristics.
In this paper, different adducts of IBX, in particular with pyridine
(PIBX), quinoline (QUIBX), and nicotinamide (B3-IBX), have been structurally
characterized using state-of-the-art X-ray powder diffraction (XRPD)
methods. Their oxidative properties have been tested and compared
to those of pristine IBX. While generally structure determination
from XRPD does not allow us to investigate the proton position, a
strategy was devised based on the investigation of iodine–oxygen
exocyclic bond lengths to discriminate between single and double iodine–oxygen
bonds. The final aim was to attempt to use XRPD to answer an elusive
question: salt or cocrystal
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
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