1,720,982 research outputs found
MODEL MIKTOARM STAR CO-, TER AND QUATERPOLYMERS. SYNTHESIS- CHARACTERIZATION-PROPERTIES
No full textMODEL MIKTOARM STAR POLYMERS OF THE TYPE A2B, A2B2, ABC AND ABCD WERE SYNTHESIZED AND CHARACTERIZED, WHERE A IS POLYSTYRENE, B IS POLYISOPRENE, C IS POLYBUTADIENE AND D IS POLY (4-METHYL STYRENE). THE MORPHOLOGICAL STUDY OF THE A2B COPOLYMERS REVEALED THAT THE PHASE BOUNDARIES OF THE COMPOSITION ARE DIFFERENT FROM THOSE OF THE CORRESPONDING AB COPOLYMERS. ALSO, THE DILUTE SOLUTION PROPERTIES OF THE A2B COPOLYMERS HAS SHOWN THAT THEIR DIMENSIONS ARE LARGER THAN THE THEORETICALLY CALCULATED ONES. THIS IS DUE TO THEIR MACROMOLECULAR ARCHITECTURE.ΠΑΡΑΣΚΕΥΑΣΤΗΚΑΝ ΚΑΙ ΧΑΡΑΚΤΗΡΙΣΤΗΚΑΝ ΠΡΟΤΥΠΑ ΜΙΚΤΟΚΛΩΝΑ ΑΣΤΕΡΟΕΙΔΗ ΠΟΛΥΜΕΡΗ ΤΟΥΤΥΠΟΥ Α2Β, Α2Β2, ABC ΚΑΙ ABCD, ΟΠΟΥ Α ΠΟΛΥΣΤΥΡΕΝΙΟ, Β ΠΟΛΥΙΣΟΠΡΕΝΙΟ, C ΠΟΛΥΒΟΥΤΑΔΙΕΝΙΟ ΚΑΙ D ΠΟΛΥ(4-ΜΕΘΥΛΟ-ΣΤΥΡΕΝΙΟ). Η ΜΟΡΦΟΛΟΓΙΚΗ ΜΕΛΕΤΗ ΤΩΝ ΣΥΜΠΟΛΥΜΕΡΩΝ Α2Β ΕΔΕΙΞΕ ΟΤΙ ΟΙ ΠΕΡΙΟΧΕΣ ΣΥΣΤΑΣΗΣ ΣΤΙΣ ΟΠΟΙΕΣ ΕΜΦΑΝΙΖΟΝΤΑΙ ΟΙ ΔΙΑΦΟΡΕΣ ΜΙΚΡΟΔΟΜΕΣ ΕΙΝΑΙ ΔΙΑΦΟΡΕΤΙΚΕΣ ΑΠΟ ΤΙΣ ΑΝΤΙΣΤΟΙΧΕΣ ΤΩΝ ΠΟΛΥΜΕΡΩΝ ΑΒ. ΕΠΙΣΗΣ ΟΙ ΔΙΑΣΤΑΣΕΙΣ ΤΟΥΣ ΣΕ ΑΡΑΙΑ ΔΙΑΛΥΜΑΤΑ ΕΙΝΑΙ ΑΥΞΗΜΕΝΕΣ ΣΕ ΣΧΕΣΗ ΜΕ ΤΙΣ ΘΕΩΡΗΤΙΚΑ ΥΠΟΛΟΓΙΣΜΕΝΕΣ. ΑΥΤΟ ΟΦΕΙΛΕΤΑΙ ΣΤΗ ΜΑΚΡΟΜΟΡΙΑΚΗ ΑΡΧΙΤΕΚΤΟΝΙΚΗ ΤΩΝ ΣΥΜΠΟΛΥΜΕΡΩΝ ΑΥΤΩΝ
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
pH-responsive polypeptide-based self-assemblies as drug and gene delivery carriers
No full textCette thèse, nous avons conçu et synthétisé différents copolymères biocompatibles auto-assemblés par copolymérisation par ouverture de cycle (coROP) de trois différents N-hydroxycarboanhydride (NCA) d’alpha-aminoacides, avec du poly(oxyde d'éthylène) (POE-NH2) comme macro-amorceur, formant un bloc hydrophile. Différents degrés de polymérisation du POE ont été utilisés (DP=17,46,114), et la composition du bloc copolypeptidique amphiphile a été ajustée par coROP de l'acide L-glutamique anionique ou de la L-lysine cationique, qui apportent une charge dépendante du pH, et du comonomère L-phénylalanine dont les unités aromatiques apportent des interactions d'empilement pi-pi et servent de réservoir hydrophobe pour l'encapsulation d’un médicament. Différentes morphologies, micelles en forme de bâtonnet, nano-objets de forme ronde et structures vésiculaires, ont été obtenues via différentes techniques d'auto-assemblage (dissolution directe, nano-précipitation, dialyse directe ou hydratation directe dans l'oligo(éthylène glycol)), puis leurs propriétés physico-chimiques détaillées et leur structure ont été étudiées par un panel de méthodes de caractérisation (diffusion de la lumière, des rayons X ou des neutrons, microscopie atomique ou électronique, dichroïsme circulaire...). Les POE-block-copolypeptides à base de poly(acide L-glutamique-co-L-phénylalanine) permettent l'encapsulation et la libération de la curcumine, qui est un médicament antioxydant, anticancéreux et anti-inflammatoire (pléiotrope) très peu soluble dans l'eau, grâce à des interactions hydrophobes avec le bloc copolypeptidique contenant de la L-phénylalanine. Les nano-objets chargés de curcumine ont été formulés par nano-précipitation ou hydratation directe, et leur efficacité a été évaluée préliminairement in vitro par un test de cytotoxicité (MTT) sur des cellules HeLa natives. L'auto-assemblage de copolymères à bloc POE de poly(L-Lysine-co-L-phénylalanine) portant une charge de surface positive à pH neutre a également été étudié dans de l'eau et des solutions tampons de pH avec des techniques de caractérisation similaires. Dans le cadre d'une autre étude, des vésicules complexes polyioniques, également appelées PICosomes dans la littérature, ont été préparées à partir d'une paire de copolymères à bloc POE de charge opposée obtenus dans les chapitres précédents. Les PICosomes ont été caractérisés par la diffusion dynamique de la lumière (DLS), la diffusion de la lumière multi-angles (MALS) et également par la microscopie électronique à transmission (TEM). Dans notre étude, des complexes polyioniques avec de petits ARN interférents (siRNA) ont été préparés et leur activité d'inhibition de gène a été étudiée sur des cellules HeLa-Luc par des essais de bioluminescence in vitro (ces cellules exprimant le gène de la luciférase de la luciole). Dans une dernière partie de la thèse, nous avons synthétisé un autre type de copolymères amphiphiles, à savoir les copolymères séquencés POE-b-PTMC (poly(oxyéthylène-b-poly(triméthylènecarbonate)) qui sont semi-cristallins, biodégradables et biocompatibles. Ensuite, des nanoparticules magnétiques de différents diamètres, recouvertes d'un revêtement hydrophobe, ont été chargées dans leurs membranes afin de préparer des polymérosomes entièrement biodégradables, dotés d'une double réponse magnétique et thermosensible, pour des applications d'administration contrôlée de médicaments.In this thesis, we designed and synthesized different biocompatible self-assembling copolymers by ring opening copolymerizaton (coROP) of three different alpha-aminoacid N-hydroxycarboanhydride (NCA), with poly(ethylene oxide) (PEO-NH2) as macro-initiator, forming hydrophilic block. Different degree of polymerization of PEO were used (DP=17,46,114), and amphiphilic co-polypeptide block was composition was tuned by coROP of either anionic L-glutamic acid or cationic L-lysine, which brings a pH dependent charge, and L-phenylalanine comonomer whose aromatic units bring pi-pi stacking interactions and serve as a hydrophobic reservoir for drug encapsulation. Different morphologies, rod-like micelles, round shape nano-objects and vesicular structures, were obtained via different self-assembly techniques (direct dissolution, nanoprecipitation, direct dialysis or direct hydration in oligo(ethylene glycol)), then their detailed physicochemical properties and structure were investigated by a panel of characterization methods (light, X-ray or neutron scattering, atomic or electron microscopy, circular dichroism…). Poly(L-glutamic acid-co-L-phenylalanine) based PEO-block-copolypeptides enable encapsulation and release of curcumin , which is an antioxidant, anticancer and anti-inflammatory (pleiotropic) drug with very low water solubility, thank to hydrophobic interactions with the L-phenylalanine containing copolypeptide block. Curcumin loaded nanoobjects were formulated by nanoprecipitation or direct hydration, and their preliminary efficacy was evaluated in vitro by cytotoxicity assay (MTT) on HeLa wild type cells. Self-assembly of poly(L-Lysine-co-L-phenylalanine) PEO-block-copolymers bearing positive surface charge at neutral pH was also studied in water and pH-buffer solutions with similar characterization techniques. As a further study, polyionic complex vesicles also called PICsomes in literature were prepared from a pair of oppositely charged PEO-block-copolypeptides obtained in previous chapters. PICsomes were characterized by dynamic light scattering (DLS), multi angle light scattering (MALS) and also by transmission electron microscopy (TEM). In our study, small interfering RNA (siRNA) loaded polyionic complexes were prepared and their gene silencing activity was investigated on HeLa-Luc cells by in vitro bioluminescence assays (these cells bearing the lucirefase firefly gene). In a final part of the thesis, we synthesized another type of amphiphilic copolymer, namely PEO-b-PTMC (polyethylene oxide-b-poly(trimethylenecarbonate)) block copolymers which are semi-crystalline, biodegradable and biocompatible. Then hydrophobically-coated magnetic nanoparticles of different diameters were loaded in their membranes in order to prepare fully biodegradable polymersomes featuring a dual magneto and thermo-responsive membrane, for tunable drug delivery applications
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
