1,720,956 research outputs found
Preparation and characterization of tpp-chitosan crosslinked scaffolds for tissue engineering
Full text linkScaffolds are three-dimensional porous structures that must have specific requirements to be applied in tissue engineering. Therefore, the study of factors affecting scaffold performance is of great importance. In this work, the optimal conditions for cross-linking preformed chitosan (CS) scaffolds by the tripolyphosphate polyanion (TPP) were investigated. The effect on scaffold physico-chemical properties of different concentrations of chitosan (1 and 2% w/v) and tripolyphosphate (1 and 2% w/v) as well as of cross-linking reaction times (2, 4, or 8 h) were studied. It was evidenced that a low CS concentration favored the formation of three-dimensional porous structures with a good pore interconnection while the use of more severe conditions in the cross-linking reaction (high TPP concentration and crosslinking reaction time) led to scaffolds with a suitable pore homogeneity, thermal stability, swelling behavior, and mechanical properties, but having a low pore interconnectivity. Preliminary biocompatibility tests showed a good osteoblasts' viability when cultured on the scaffold obtained by CS 1%, TPP 1%, and an 8-h crosslinking time. These findings suggest how modulation of scaffold cross-linking conditions may permit to obtain chitosan scaffold with properly tuned morphological, mechanical and biological properties for application in the tissue regeneration field
Novel approaches to investigate the crystallization, morphology, and properties of recycled polyolefin blends
No full text265 p.This PhD thesis explores innovative methods to improve the recycling and upcycling of polyolefin blends, particularly from post-consumer waste. It focuses on understanding the structure-property relationships of these materials, addressing challenges posed by their complex and heterogeneous composition. The study introduces a reliable analytical method using Temperature Modulated DSC (TM-DSC) to determine the chemical composition of recycled polyolefin blends, with potential industrial applications. Additionally, it investigates the crystallization behavior of these blends using fast scanning calorimetry (FSC) to provide insights into self-nucleation and crystallization kinetics under high cooling rates. The research also explores the use of commercial block copolymers as compatibilizers to enhance phase dispersion, interfacial adhesion, and mechanical properties, making the recycled materials suitable for high-value applications
Isothermal crystallization of polyethylene droplets within the self-nucleated isotactic polypropylene matrix of a 70/30 iPP/PE immiscible blend via fast scanning chip calorimetry (FSC)
No full textThe escalating volume of waste related to polyolefins poses recycling challenges. Given the mixed composition of the post-consumer feedstock, studying blends of virgin polyolefins is a fruitful strategy to simulate such compositions. For the first time, this study investigates crystallization, self-nucleation (SN), and kinetics of a 70/30 iPP/PE blend, characterised by a “sea-island” morphology, using fast scanning calorimetry (FSC). Preliminary experiments on different chip sensors proved the technique's sensitivity and representativeness for polymer blends, even with minimal sample quantities. Application of the self-nucleation thermal protocol (employing fast scanning rates, from 500 to 1000 °C/s) to the iPP matrix phase revealed insights into the characteristic SN domains. The crystallization kinetics of PE-dispersed droplets within a SN iPP matrix was also investigated. Results indicate a 30 °C crystallization window for PE droplets within the self-nucleated iPP matrix, expanding the understanding of crystallization rates (up to four decades) compared to standard DSC measurements
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
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