1,721,015 research outputs found
Application of carbon-based quantum dots in photodynamic therapy
No full textPhotodynamic Therapy (PDT) is a non-invasive therapeutic modality that can treat a wide variety of cancer types by means of photosensitizer drug, light, and oxygen. Due to enhanced specificity and fewer side effects, PDT can be an alternative approach for cancer treatments. However, conventional photosensitizers (PSs) exhibit low selectivity, hydrophobicity, and limited photophysical properties. Nanotechnology emerges as a potential solution to these issues and improves PDT efficiency. Nanomaterials such as Carbon Quantum Dots (CQDs) and Graphene Quantum Dots (GrQDs) have been widely applied on PDT research recently, regarding their excellent photoluminescence properties, biocompatibility, as well as their hydrophilicity. The present review article summarizes the main features of PDT and carbon-based quantum dots with an emphasis on used PSs and methods for synthesis of carbon dots. Additionally, the most recent applications of CQDs and GrQDs in PDT have been extensively discussed. The main conclusion that arises is that carbon-based quantum dots seem to be a powerful tool in cancer diagnosis and treatment
Isolation and Characterization of All Eight Bisadducts of Fulleropyrrolidine Derivatives
No full textWe report the isolation and characterization of bisadducts of fulleropyrrolidine derivatives. The
compounds were characterized by means of a variety of spectroscopic techniques, including ESMS,
UV-vis, 1H NMR, and 13C NMR. The whole series of bisadducts was separated for the first
time in the case of the bispyrrolidines, and the determination of their structure was obtained by
NMR spectroscopy with the help of HMQC and HMBC techniques
Absorption spectra of the mono-adduct and the eight bis-addict regioisomers of pyrrolidine derivatives of C60
No full textAbsorption spectra of the pyrrolidine N-mTEG (mTEG1⁄4CH2CH2OCH2CH2OCH2CH2OCH3) mono-adduct and
eight bis-adducts of C60 were studied in the 230–800 nm spectral range. The five-membered ring adducts contain an
apex nitrogen atom. A theoretical discussion in terms of the effective electronic structures and transitions of these
species shows that a filiation between spectra of C60, and its pyrrolidine mono- and bis-adduct derivatives can be expected
and rationalised. Allowed transitions in the ultraviolet are related to fullerene core electronic transitions and are
observed to be little affected in energy and in transition strength by the mono-adduct, apart from band splitting or
broadening associated with the lowered molecular symmetry with respect to C60, whereas in the visible region, the
transitions related to C60 forbidden transitions are significantly modified by the adduct. The bis-adducts have similar
general spectral behaviour to that of the mono-adduct, with differences that reflect the relative position of the two
addends but are found to be not dependent on membership of any of the three formal symmetry groups into which the
bis-adducts can be classified. The second pyrrolidine adduct reinforces the perturbation of the forbidden and, to a lesser
extent, the allowed transitions of the fullerene core. From a comparison with the spectra of C60[C(COOEt)2] and its bisadducts,
it was concluded that the N atom in the pyrrolidine five-membered ring adduct is a less efficient blocker of
through-bond and/or through-space communication than the sp3 carbon atom in Bingel–Hirsch methanofullerenes
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
Incorporation of fullerene derivatives into smectite clays: A new family of organic-inorganic nanocomposites
No full textThree fulleropyrrolidine derivatives, characterized by the presence of positive charges, were introduced in the interlayer space of montmorillonite. The composites were characterized by powder X-ray diffraction and differential thermal and thermogravimetric (DTA-TGA) analysis, in conjunction with FTIR, UV-Vis, Raman, and Fe-57-Mossbauer spectroscopies. Organophilic derivatives were intercalated into organically modified clays, while water-soluble fulleropyrrolidines were introduced into the clay galleries through ion exchange. The experiments, complemented by computer simulations, show that not all the clay-clay platelets are intercalated by the fullerene derivatives and that a sizable amount of charge transfer takes place between the host and the guests
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
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