1,720,967 research outputs found
Crystal forms of the hydrogen oxalate salt of o-desmethylvenlafaxine
No full textOBJECTIVES: To prepare new crystalline forms of the antidepressant o-desmethylvenlafaxine salt as potential new commercial forms and evaluate their physicochemical properties, in particular the dissolution rate.
METHODS: A new hydrogen oxalate salt of o-desmethylvenlafaxine hydrogen oxalate (ODV-OX) was synthesized, and a polymorph screening was performed using different solvents and crystallization conditions. Crystalline forms were characterized by a combination of solid-state techniques: X-ray powder diffraction, differential scanning calorimetry, thermogravimetric analysis, FT-IR spectroscopy and single crystal X-ray diffraction. The stability of all crystalline phases was tested under International Conference on Harmonisation (ICH) conditions (40°C and 75% Relative Humidity (RH)) for 1 week. Dissolution tests were performed on the hydrogen oxalate salt ODV-OX Form 1 and compared with dissolution test on the commercial form of the succinate salt of o-desmethylvenlafaxine.
KEY FINDINGS: Five crystalline forms of ODV-OX were isolated, namely three hydrated forms (Form 1, Form 2, Form 3) and two anhydrous forms (Form 4 and Form 5).
CONCLUSIONS: Comparative solubility tests on ODV-OX Form 1 and o-desmethylvenlafaxine succinate evidenced a significant increase in solubility for the hydrogen oxalate salt (142g/l) with respect to the succinate salt (70g/l)
Molecular Salts of Anesthetic Lidocaine with Dicarboxylic Acids: Solid-State Properties and a Combined Structural and Spectroscopic Study
No full textFour lidocaine molecular salts of dicarboxylic acids (oxalic, fumaric, malonic, and succinic) were synthesized and characterized by a combined use of X-ray power and single-crystal diffraction, differential scanning calorimetry, Fourier transform infrared spectroscopy (FT-IR), and solid-state NMR (H-1 MAS and CRAMPS, and C-13 and N-15 CPMAS); all molecular salts show a dramatic increase in their melting point with respect to both lidocaine and lidocaine hydrochloride, and a higher dissolution rate and thermodynamic solubility in physiological solution with respect to the free base
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
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
Using Salt Cocrystals to Improve the Solubility of Niclosamide
Full text linkThis Article reports the solvent-free synthesis and characterization of a number of different crystal forms of niclosamide (HNic), which is an API belonging to the Salicilamide class. The synthesized compounds are four new salt cocrystals (KNic.HNic.H2O, KNic.HNic.3H(2)O, NaNic.HNic.3H(2)O, NaNic.HNic.2H(2)O), a classic cocrystal with imidazole (IM) (HNic.IM), and two sodium salts, (NaNic.DMSO.H2O and NaNic.DMSO.2H(2)O). The peculiarity of these salt cocrystals is the APIs concomitant presence as both a neutral component and as a salt coformer and the fact that they interact via hydrogen bond formation. HNics poor aqueous solubility makes the enhancement of its dissolution rate via the modulation of its physical properties extremely important. All samples have been investigated using a combination of solid-state experimental techniques which provide complementary information on powdered samples. These techniques are X-ray powder diffraction, solid-state NMR, IR, and Raman. Single crystals were only obtained for KNic.HNic.H2O and NaNic.DMSO.2H(2)O. The nature of the adducts (whether salt or cocrystal), their stoichiometry and the presence of independent molecules in the unit cell of the other samples were thus all determined by means of solid-state NMR and the comparative analysis of C-13 and N-15 CPMAS (Cross-Polarization Magic Angle Spinning) and 1H MAS spectra. Furthermore, differential scanning calorimetry, thermogravimetric analysis and intrinsic dissolution rate measurements completed the characterization and enabled us to evaluate the effects of microscopic changes (molecular packing, weak interactions, conformations, etc.) on the macroscopic properties (thermal stability and bioavailability) of the multicomponent forms. The results obtained indicate that the formation of salt cocrystals provides a reliable method with which to improve the HNic intrinsic dissolution rate
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