1,720,974 research outputs found
PEGylation and preliminary biocompatibility evaluation of magnetite–silica nanocomposites obtained by high energy ball milling
No full textHigh energy ball milling (HEBM) has been used for the first time to prepare PEGylated magnetite–silica
(Fe3O4–SiO2) nanocomposites intended to be used for biological purposes. Surface amine groups were
introduced by a silanization reaction involving 3-aminopropyl triethoxysilane (APTS) followed by PEGylation
to yield long-term stable and stealth nanocomposites of 200nm in diameter. The efficient coverage
by PEG chains was shown by isothermal titration calorimetry (ITC) where PEGylated nanocomposites
did not interact with BSA compared to non-PEGylated counterparts which led to a significant change in
enthalpy. By cell viability (MTT) assays and cell morphology investigations, it was evidenced that PEGylated
Fe3O4–SiO2 nanocomposites did not provide any appreciable cytotoxicity on J774 macrophage and
MCF-7 breast cancer cell lines. Furthermore, noticeable internalization was evidenced by J774 cells with
PEGylated Fe3O4–SiO2 nanocomposites in contrast to MCF-7 cells, in good agreement with the respective
tendency of each cell line for endocytosis
Mechanochemical reactivity of square-planar nickel complexes and pyridyl-based spacers for the solid-state preparation of coordination polymers: the case of nickel diethyldithiophosphate and 4,4′-bipyridine
No full textThe mechanochemical synthesis of a coordination polymer from a preformed metal coordination complex and a pyridyl-based spacer has been successfully performed. The coordination polymer (1·L)∞ was obtained rapidly from the reaction of the neutral square-planar complex [{(EtO)2PS2}2Ni] (1) and 4,4′-bipyridine (L) at room temperature through two different mechanochemical approaches (neat grinding and liquid-assisted grinding). The products were characterized by X-ray powder diffraction, IR spectroscopy, scanning electron microscopy, thermogravimetry and differential scanning calorimetry techniques. In parallel (1·L)∞ was prepared by conventional solvent-based methods, and the X-ray crystal structure of the polymer, obtained as single crystals, was compared with that from the mechanochemical preparation
High Energy Ball Milling and Liquid Crystal Template Method: A Successful Combination for the Preparation of Magnetic Nano-Platforms
No full textIn this study, we present the preparation of superparamagnetic ordered mesoporous silica (SOMS) for biomedical applications by the combination of high energy ball milling (HEBM) and the liquid crystal template method (LCT) to produce a material comprised of room temperature superparamagnetic Fe3O4 nanoparticles in a MCM-41 like mesostructured silica. In a typical synthesis, a mixture of Fe2O3 and silica was sealed in a stainless-steel vial with steel balls. Ball milling experiments were performed in a vibratory mill apparatus. The milling process produced nanocomposites with an average size ranging from ∼100-200 nm, where the Fe3O4 nanoparticles (4.8 nm size) are homogeneously dispersed into the amorphous SiO2 matrix. The obtained nanocomposite has been used for the preparation of the SOMS through the LCT method. Structural, morphological and textural characterization were performed using X-ray powder diffraction, transmission electron microscopy and nitrogen sorption analysis. Field dependence of magnetization was investigated and showed superparamagnetic behaviour at 300 K with a value of saturation magnetization (Ms) that is of interest for biomedical applications
CAFFEINE-SILICA NANOCOMPOSITE AS A DRUG DELIVEY SYSTEM: SYNTHESIS, CHARACTERIZATION AND IN VITRO SKIN PERMEATION STUDY
No full text
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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