1,721,058 research outputs found
Study of atomization mechanism of gas/liquid mixtures flowing through Y-jet atomizers
No full textThe atomization mechanism of gas/liquid mixtures flowing through Y-jet atomizers has been studied by examining both the internal and external flow patterns. Air and water were used as the test fluids. Atomizers with transparent mixing ports were used to visualize the internal flow patterns, and the drop sizes were measured to examine the spraying performance. The liquid/gas momentum ratio was considered to be the appropriate parameter to describe both the internal flow and spray characteristics. A comprehensive physical model describing the atomization process is proposed; the process consists of ''direct collision,'' ''drop entrainment/deposition,'' and ''liquid film disintegration.'' The validity of the model is also checked with the drop size distribution data. It is confirmed that the trend of the circumferential film thickness variation within the mixing port coincides with variation of the spatial distribution of spray drops
Disintegration of Annular Liquid Sheet With Core Air Flow Mode Classification
No full textDisintegration mechanism of an annular liquid sheet with a core-gas flow has been studied experimentally. Air and water were used as the test fluids, respectively. Two nozzles with different annulus gaps were prepared to find out the effect of the liquid film thickness on the breakup mode qualitatively. The breakup modes were identified from the high-speed spark photographs. The backward illumination method was adopted for flow visualization. There exist at least three different modes of disintegration, namely, Rayleigh, bubble-breakup, and pure-pulsating modes depending on the air and water flow rates. Tentative maps representing those disintegration modes were provided with the liquid film Reynolds number and the aerodynamic Weber number taken as the dimensionless parameters
Immobilization of cell adhesive RGD peptide onto the surface of highly porous biodegradable polymer scaffolds fabricated by a gas foaming/salt leaching method
No full textA cell adhesive peptide moiety, Gly-Arg-Gly-Asp-Tyr (GRGDY), was immobilized onto the Surface of highly porous biodegradable polymer scaffolds for enhancing cell adhesion and function. A carboxyl terminal end of poly(D,L-lactic-co-glycolic acid) (PLGA) was functionalized with a primary amine group by conjugating hexaethylene glycol-diamine. The PLGA-NH2 was blended with PLGA in varying ratios to prepare filius by solvent casting or to fabricate porous scaffolds by a gas foaming/salt leaching method. Under hydrating conditions, the activated GRGDY Could be directly immobilized to the surface exposed amine Groups of the PLGA-NH2 blend films or scaffolds. For the PLGA blend films, the surface density of GRGDY, surface wettability change. and cell adhesion behaviors were characterized. The extent of cell adhesion was substantially enhanced by increasing the blend ratio of PLGA-NH2 to PLGA. The level of an alkaline phosphatase activity, measured as a degree of cell differentiation. was also enhanced as a result of the introduction of cell adhesive peptides. (C) 2004 Elsevier Ltd. All rights reserved.the Korea Science and
Engineering Foundation (R01-2003-000-10362-0) and
the Korea Research Foundation (X01524), Korea
Lysozyme microencapsulation within biodegradable PLGA microspheres: Urea effect on protein release and stability
No full textLysozyme was encapsulated within biodegradable poly(D,L-lactide-co-glycolide) microspheres by a double emulsion solvent evaporation method for studying its release mechanism associated with protein stability problems. When urea, a protein unfolding agent, was added into the incubation medium lysozyme release rate from the microspheres increased with the increase in urea concentration. The enhanced lysozyme release was attributed to the suppression of protein aggregation, to the facilitated diffusion of unfolded lysozyme by an efficient reptile motion of unfolded protein molecules through porous channels in microspheres, and to the largely decreased extent of nonspecific protein adsorption onto the enlarged surface area of degrading polymer microspheres in the presence of urea. Encapsulating lysozyme in an unfolded form within PLGA microspheres was attempted by using urea as an excipient. This new urea-based formulation exhibited a more sustained lysozyme release profile than the control formulation, and released lysozyme from the microspheres showed a much less amount of lysozyme dimer population while maintaining a correct conformation after refolding in the incubation medium. This study provides new insights for the formulation of protein encapsulated PLGA microspheres. (C) 2000 John Wiley & Sons, Inc
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
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