1,721,015 research outputs found
Effetti della somministrazione di steroidi sulla differenziazione della gonade di anguilla
No full textDopo 6 e 10 mesi dall'inizio del trattamento:
a) le anguille di controllo esaminate avevano o gonadi indifferenziate in diversi stadi di sviluppo in relazione all'accrescimento corporeo o organi di Syrski;
b) le anguille trattate con MT avevano gonadi indifferenziate e organi di Syrski simili ai controlli o a struttura anomala con poche cellule germinali e con tessuto connettivo abbondante;
e) tra le anguille trattate con EE, quelle di lunghezza inferiore ai 15 cm avevano gonadi indifferenziate, mentre tutte le altre presentavano ovari differenziati con oociti previtellogenici e vitellogenici iniziali.
Dai risultati di questi esperimenti è evidente un effetto femminilizzante sulla gonade da parte dell'EE che, inoltre, stimola lo sviluppo degli oociti
3D bioprinting of cell-laden carbopol bioinks
Full text linkTraditional in vitro culture models are unable to fully reflect the organ microenvironment, due to differences in terms of cell morphology, protein expression, cell-cell and cell-matrix interactions, and drug response. In contrast, the flexibility of bioprinting modes allows for the deposition of cell-containing biomaterials in any free-form-inspired 3D structures on chip. The main purpose of this study was to design and optimize commercially available Carbopol-based 3D printing formulations, because of their many advantages, such as low-cost, the ability to produce clear and stable gels, and the water thickening. For this purpose, three different Carbopol gels (EDT 2020 NF, Ultrez 10 NF and NF-980) were tested in terms of printability and biocompatibility, with lung cancer epithelial (A549) and normal lung fibroblast (MRC-5) cells. This study demonstrates that Carbopol is a promising candidate for the 3D printing of cell-laden constructs, both in terms of rheology and printing performance
Thermal response and thermochromism of methyl red-based copolymer systems-coupled responsiveness in critical solution behaviour and optical absorption properties
Full text linkUntil now, only limited experimental knowledge and sparse theoretical treatment about the mechanisms of thermochromism of azo dyes in solution has been available. Especially the coupling of thermoresponsiveness of polymers with the inherent thermochromism of azo dyes is attractive to enhance the optical response for applications like polymeric optical pH- and temperature-dual sensors. To elucidate the different mechanisms contributing to the thermochromism of such azo chromophores, we synthesised monomers based on the constitutional isomers of the common pH indicator methyl red. The ortho-isomer was copolymerised with hydrophilic monomers and the photocrosslinker benzophenone acrylamide, with the resulting copolymers being converted to networks by irradiation with UV-light and yielding hydrogels after swelling with water. N-Isopropylacrylamide was used as comonomer to introduce thermoresponsiveness in the polymers in form of a lower critical solution temperature (LCST) behaviour. Three different dye systems with varying protonation states were investigated by temperature-dependant UV-vis spectroscopy: as monomers in solution, as part of copolymers in solution, and as photocrosslinked hydrogels. Consequently, we were able to identify the four different mechanisms of vibronic thermochromism, thermo-solvatochromism, thermo-perichromism and thermo-halochromism. Their interplay was investigated by choosing appropriate combinations of solvents, acid and comonomers. The LCST behaviour of the N-isopropylacrylamide copolymers could be exploited to strongly influence thermochromism, providing insight into the mechanisms of critical solution behaviour of polymers and thermochromism alike. The experimental data suggest that various thermochromic mechanisms act simultaneously and mutually influence each other, specifically with thermo-solvato- and thermo-perichromism affecting thermo-halochromism. These effects are best described by the terms thermo-solvato-halochromism and thermo-peri-halochromism. Notably, on the basis of the identified thermochromic mechanisms prevailing in the monomer solutions, the behaviour of the more complex polymer systems can be elucidated, and consequently, the distinct properties of the dye in combination with polymer-inherent phenomena can be deduced. To our knowledge, this is the first comprehensive study to harmonise the understanding of the different thermochromic mechanisms in azobenzene, their mutual action, and the strong influence of thermoresponse on thermochromism
3D Cell Culture: Recent Development in Materials with Tunable Stiffness
Full text linkIt is widely accepted that three-dimensional cell culture systems simulate physiological conditions better than traditional 2D systems. Although extracellular matrix components strongly modulate cell behavior, several studies underlined the importance of mechanosensing in the control of different cell functions such as growth, proliferation, differentiation, and migration. Human tissues are characterized by different degrees of stiffness, and various pathologies (e.g., tumor or fibrosis) cause changes in the mechanical properties through the alteration of the extracellular matrix structure. Additionally, these modifications have an impact on disease progression and on therapy response. Hence, the development of platforms whose stiffness could be modulated may improve our knowledge of cell behavior under different mechanical stress stimuli. In this review, we have analyzed the mechanical diversity of healthy and diseased tissues, and we have summarized recently developed materials with a wide range of stiffness
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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