1,721,045 research outputs found
Flow-induced crystallization of a Poly(Lactic acid): Effect of the application of low shear rates on the polymorphous crystallization
No full textThe study of the crystallization process of biodegradable polymers is crucial to predict the final properties of the industrial plastic parts. In this work, the effect of the application of low shear rates on the polymorphous crystallization of the Poly (lactic acid), PLA, has been studied. Results in terms of nucleation and growth rate of crystalline structures in the spherulitic regime revealed a non-monotonous dependence of the growth rate upon the shear rate. DSC and WAXD analyses on samples crystallized at 120 °C allowed to assess that in quiescent conditions the more ordered α phase prevails, but even at low shear rates a predominance of the α′ phase can be found. By increasing the shear rate, the amount of the more ordered α phase increases again. The transition from α′ to α seems to inhibit the spherulitic growth rate, that reaches a relative minimum at γ ̇ = 0.2 s−1. Similar observations hold true also at other temperatures in the range 110–130 °C. A further increase in the shear rate leads to a large prevalence of the α-phase, as in the case of quiescent conditions
Effect of the application of low shear rates on the crystallization kinetics of PLA
No full textFlow-induced crystallization can effectively increase the crystallinity content in poly(lactic acid) parts, and this can be extremely significant since an increase of crystallinity for this material dramatically enhances many properties among which the heat resistance. This work analyzes nucleation and growth rate of spherulites formed during crystallization process of PLA at different temperatures and shear rates. The application of a shear flow results in an enhancement of the nucleation phenomena, with the formation of a new population of nuclei, and an improvement of the crystals growth already at low values of shear rates. Furthermore, it is possible to find a dependence of the equilibrium melting temperature upon the Weissenberg number
Comment on “LncRNA 00152 promotes the development of hepatocellular carcinoma by activating JAK2/STAT3 pathway”
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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
Nucleation and Growth Rate of a Poly(Lactic Acid) in Quiescent Conditions
No full textPoly(lactic acid) (PLA) is a biodegradable thermoplastic polyester produced from renewable sources that can be easily processed to obtain articles to be used in many applications, from commodities to electronics. The large influence of the crystalline structures and morphology on the biodegradation rate, as well as on the other material properties, led to an ever-increasing interest in the study of the crystallization behaviour of PLA. In this work, experiments on the crystallization kinetics of PLA were carried out by means of optical observations considering the nucleation and growth phenomena of the PLA crystals under quiescent conditions
Influence of allopurinol on the half-life of tolbutamide and rifamycin-SV in blood of healthy volunteers
No full textThe influence of treatment with allopurinol (5 mg/kg/die for 15 days) on T/2 of tolbutamide and rifomycin-SV intravenously administered, has been studied in 10 healthy volunteers. We have observed reduction of T/2 of tolbutamide and, on the contrary, prolongation of T/2 of rifamycin-SV. Tolbutamide behaviour was unexpected, considering that other Authors had previously found inhibition of metabolic degradation of other drugs metabolized by the microsomal enzymes. We conclude that data concerning the influence of a drug (in our case, allopurinol) on the metabolism of another drug cannot always authorize general deduction and previsions regarding the metabolic interferences on the pharmacokinetics of other substances
New aircraft anti/de-icing technologies
No full textThe ice formation on the leading edge of aircraft wings is a crucial problem for aircraft flight. In this work, an efficient method for the anti/de-icing function based on the development of electro-conductive film heaters is prosed. A green solvent casting process is employed in the experimental procedure adopted for the film preparation. Two kinds of expanded graphite have been used. The different morphological feature of the two expanded graphites affects the heating performance of the films heaters. The film prepared using the nanoparticles with a higher aspect ratio manifests better electrical and heating performance, and therefore the de-icing activation at a lower applied voltage
Influence of phenobarbital on hyperbilirubinemia caused by nicotinic acid and rifamycin--SV in healthy subjects
No full textTen healthy subjects have been given before and after treatment with phenobarbital the following intravenous charges: a) nicotinic acid; b) rifamicyn-SV; c) simultaneous administration of the two drugs. Along with confirmatory evidence of the wellknown increase in bilirubinaemia (prevalently unconjugated), we have observed phenobarbital to attempts partially yet significantly that effect. On the base of direct experience on rat liver, we hypothise phenobarbital to increase the pool of the Y protein carrying cholephilic organic anions into the hepatocytes
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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