1,721,102 research outputs found
CAPSULAR DEVICES FOR ORAL MODIFIED RELEASE OF DRUGS PREPARED BY INJECTION MOLDING
Full text linkThe research project was focused on the development of a pulsatile capsular-shaped drug delivery system (DDS) named ChronocapTM. It consists of a capsule shell, made of hydroxypropyl cellulose (HPC), prepared by injection molding (IM); it is intended to be filled with different types of drug preparations and to delay their liberation after oral administration. Such devices prepared by means of a prototype mold were demonstrated able to convey drug preparations giving rise to the expected pulsatile release performance, confirmed by in vivo data. The PhD project was undertaken aiming at improving the robustness and versatility of the ChronocapTM device as well as enhancing the industrial scalability of its manufacturing process. For this purpose, two different tasks were pointed out: the improvement of the manufacturing process and of the technological characteristics of capsules on the one side, and the upgrade of applications of the device on the other. In this respect, the modulation of the lag phase of the capsular device and its possible exploitation in the design of a colon DDS were approached
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
Development of an im mold purposely devised for an oral pulsatile-release capsular device
No full textInjection molding (IM) was recently proposed as the manufacturing technique for the preparation of an oral capsular device (ChronocapTM) based on hydroxypropyl cellulose (HPC) and intended for pulsatile and/or colonic delivery. By employing a prototype mold, it was possible to obtain capsules able to impart a lag phase to the release of a model drug, both in vitro and in vivo, the duration of which was dependent on the shell thickness and composition [1,2]. As some technical limitations were encountered with respect to the mold, manufacturing process and molded items, the aim of the present work was the development of a novel mold to enhance the industrial scalability of the ChronocapTM pulsatile delivery device.
Preliminarily, a formulation was selected composed of HPC (Klucel® LF) plasticized with polyethylene glycol 1500, and the relevant thermal, rheological and mechanical characteristics were in-depth evaluated. The need for a plasticizer was confirmed and its amount was related to the IM processability and mechanical stability of the molded items. Moreover, potential risks connected with the operating temperatures and heating time of the material were highlighted. Based on the results obtained, some changes were introduced into the press (e.g. reduced diameters of the piston and nozzle) and a novel mold was designed with several improved features (e.g. hot runner and consistent/reduced flow length in all directions). After adjusting the process parameters a fully automated manufacturing process was achieved with a cycle time reduced to about 5 s and no need for lubricants. The capsular devices prepared demonstrated good technological properties and improved reproducibility of the shell thickness, mechanical properties as well as release performance.
[1] A. Gazzaniga et al., AAPS PharmSciTech 12, 295-303, 2011;
[2] A. Gazzaniga et al., 38th CRS annual meeting & exposition July 30 - August 3, National Harbor, Maryland
Release performance of injection-molded HPC-based capsules filled with different formulations of a model drug
No full textPurpose.
To compare the dissolution and lag time in drug release from hydroxypropyl cellulose (HPC)-based capsules to conventional gelatin and hydroxypropyl methylcellulose (HPMC) capsules.
Methods.
Capsules made from a mixture of 90:10 HPC (Klucel® LF, Ashland):PEG1500 were produced by injection molding (BabyPlast 6/10P, Cronoplast S.L.). Weight and dimensions for the HPC-based capsules and commercially available size 0 gelatin and HPMC capsules (Capsugel) were determined. Scanning electron microscopy (SEM) was used to image the different capsules. Acetaminophen (AAP) was used as the model drug. Capsules were filled with different formulations of AAP, including fine powder, granules, pellets, and semi-solid. The capsules were then subjected to dissolution testing. Drug release in deionized water at 37°C as a function of time was determined by UV/Vis spectrophotometry. Lag time in drug release (expressed as time for 10% of drug to be released) as well as the time for between 10 and 90% drug release (as a measure of burst effect) were determined.
Results.
HPC-based capsules were similar in diameter with respect to gelatin and HPMC capsules, but about 7mm shorter in length. The weight of the HPC capsule was noticeably higher than conventional capsules (229 vs ~90 mg), due to the properties of the polymer and the thickness of the capsule shell. With respect to release performance, when AAP fine powder was used as the filling formulation, HPC-based capsules showed a lag time roughly 34 minutes longer than conventional capsules. Moreover, the burst effect observed when evaluating the relevant release patterns was comparable (approximately 5 min). Results were confirmed when capsules were filled with other formulations of AAP. In particular, lag time in drug release from HPC capsules ranged from 36 (±3.36) minutes for fine powder up to 45 (±7.27) minutes for pellets, compared to 3.4 (±1.56) and 6.4 (±7.17) minutes, respectively, for gelatin capsules.
Conclusion.
The overall results demonstrated that HPC-based capsules exhibit a lag phase of approximately 34 minutes prior to drug release, significantly longer than conventional capsules. These novel capsules confirmed to be useful in delayed drug release applications. Moreover, the lag time in drug release was independent from the filling formulation
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