1,720,962 research outputs found
Engineered extracellular vesicles as a reliable tool in cancer nanomedicine
Full text linkFast diagnosis and more ecient therapies for cancer surely represent one of the huge
tasks for the worldwide researchers’ and clinicians’ community. In the last two decades, our
understanding of the biology and molecular pathology of cancer mechanisms, coupled with the
continuous development of the material science and technological compounds, have successfully
improved nanomedicine applications in oncology. This review argues on nanomedicine application
of engineered extracellular vesicles (EVs) in oncology. All the most innovative processes of EVs
engineering are discussed together with the related degree of applicability for each one of them in
cancer nanomedicines
Piezo/sono-catalytic activity of ZnO micro/nanoparticles for ROS generation as function of ultrasound frequencies and dissolved gases
Full text linkWe report an accurate study on sonocatalytic properties of different ZnO micro and nanoparticles to enhance OH radical production activated by cavitation. In order to investigate some of the still unsolved aspects related to the piezocatalytic effect, the degradation of Methylene Blue and quantification of radicals production have been evaluated as function of different ultrasonic frequencies (20 kHz and 858 kHz) and dissolved gases (Ar, N2 and air). The results shown that at low frequency the catalytic effect of ZnO particles is well evident and influenced by particle dimension while at high frequency a reduction of the degradation efficiency have been observed using larger particles. An increase of radical production have been observed for all ZnO particles tested while the different saturating gases have poor influence. In both ultrasonic set-up the ZnO nanoparticles resulted the most efficient on MB degradation revealing that the enhanced radical production may arise more from bubbles collapse on particles surface than the discharge mechanism activate by mechanical stress on piezoelectric particles. An interpretation of these effects and a possible mechanism which rules the sonocatalytic activity of ZnO will be proposed and discussed
The Synergistic Effect of Nanocrystals Combined With Ultrasound in the Generation of Reactive Oxygen Species for Biomedical Applications
Full text linkReactive oxygen species (ROS) effects on living cells and tissues is multifaceted and their level or dose can considerably affect cell proliferation and viability. It is therefore necessary understand their role also designing ways able to regulate their amount inside cells, i.e., using engineered nanomaterials with either antioxidant properties or, for cancer therapy applications, capable to induce oxidative stress and cell death, through tunable ROS production. In this paper, we report on the use of single-crystalline zinc oxide (ZnO) round-shaped nanoparticles, yet ZnO nanocrystals (NCs) functionalized with amino-propyl groups (ZnO-NH2 NCs), combined with pulsed ultrasound (US). We show the synergistic effects produced by NC-assisted US which are able to produce different amount of ROS, as a result of inertial cavitation under the pulsed US exposure. Using Passive Cavitation Detection (PCD) and Electron Paramagnetic Resonance (EPR) spectroscopy, we systematically study which are the key parameters, monitoring, and influencing the amount of generated ROS measuring their concentration in water media and comparing all the results with pure water batches. We thus propose a ROS generation mechanism based on the selective application of US to the ZnO nanocrystals in water solutions. Ultrasound B-mode imaging is also applied, proving in respect to pure water, the enhanced ecographic signal generation of the aqueous solution containing ZnO-NH2 NCs when exposed to pulsed ultrasound. Furthermore, to evaluate the applicability of ZnO-NH2 NCs in the biomedical field, the ROS generation is studied by interposing different tissue mimicking materials, like phantoms and ex vivo tissues, between the US transducer and the sample well. As a whole, we clearly proof the enhanced capability to produce ROS and to control their amount when using ZnO-NH2 NCs in combination with pulsed ultrasound anticipating their applicability in the fields of biology and health care
Modulation of sonochemical reactions by cavitation driven thermal degradation of aqueous salts solutions
Full text linkStrategies for controlling or increasing the yield of radical reactions generated by
ultrasonic cavitation in aqueous media have been the object of research for many
years. Past studies have focused on the role of organic solvents in increasing
Reactive Oxygen Species (ROS) formation or have investigated the effect of
ultrasound on accelerating the OH radicals generation from Fenton reactive. More
recently, piezoelectric micro
-nanoparticles have shown a synergistic effect in
activating specific reactions and increasing radicals production from ultrasound.
Here we report the generation of ROS together with H
2 evolution or increase of
oxidizing species during ultrasonic treatments of homogeneous concentrated
aqueous solutions of simple salts as acidic phosphates, potassium sodium tartrate
and alkaline nitrate
s. An increase in organic dye degradation efficiency, and the
increase of reducing or oxidizing species compared with pure water has been
found. The activation mechanism revealed a new, unexpected, approach to
enhance the efficiency of sono
-catalysed reactions in aqueous media for
environmental or energy application
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
Gold nanoparticles radio-sensitize and reduce cell survival in lewis lung carcinoma
Full text linkIt has been suggested that particle size plays an important role in determining the genotoxicity of gold nanoparticles (GNPs). The purpose of this study was to compare the potential radio-sensitization effects of two different sized GNPs (3.9 and 37.4 nm) fabricated and examined in vitro in Lewis lung carcinoma (LLC) as a model of non-small cell lung cancer through use of comet and clonogenic assays. After treatment with 2Gy X-ray irradiation, both particle sizes demonstrated increased DNA damage when compared to treatment with particles only and radiation alone. This radio-sensitization was further translated into a reduction in cell survival demonstrated by clonogenicity. This work indicates that GNPs of both sizes induce DNA damage in LLC cells at the tested concentrations, whereas the 37.4 nm particle size treatment group demonstrated greater significance in vitro. The presented data aids in the evaluation of the radiobiological response of Lewis lung carcinoma cells treated with gold nanoparticles
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
- …
