1,721,135 research outputs found
Extraction efficiency of different microplastic polymers from deep-sea sediments and their quantitative relevance
Full text linkAn increasing number of methods for extracting microplastic particles from marine sediments have been published but without evaluating the extraction efficiency. Furthermore, while most of the procedures developed have been applied to sandy sediments from shallow water habitats, specific and standardized procedures for deep-water sediments (> 200 meters deep) are limited. In this study, we describe a specific protocol for extracting microplastics (2- 1000 μm) from deep-sea sediments and for quantifying and identifying them. We also assessed its extraction efficiency, which resulted in a high recovery (on average ca. 60%, and up to 80%) particularly, for polyethylene, polypropylene, and polystyrene. This method can be applied to all fine-grained/muddy sediments and allows the extraction of even the smallest fraction of microplastics (<20 μm), which are expected to have the most severe effects on marine biodiversity and ecosystem functioning and ultimately also have implications for human health
Single step plasma deposition of hydrocarbon thin films containing Pt nanoclusters for fuel cells applications
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DNA damage and repair following In vitro exposure to two different forms of titanium dioxide nanoparticles on trout erythrocyte
Full text linkTiO(2) has been widely used to promote organic compounds degradation on waste aqueous solution, however, data on TiO(2) nanotoxicity to aquatic life are still limited. In this in vitro study, we compare the toxicity of two different families of TiO(2) nanoparticles on erythrocytes from Oncorhynchus mykiss trout. The crystal structure of the two TiO(2) nanoparticles was analyzed by XRD and the results indicated that one sample is composed of TiO(2) in the anatase crystal phase, while the other sample contains a mixture of both the anatase and the rutile forms of TiO(2) in a 2:8 ratio. Further characterization of the two families of TiO(2) nanoparticles was determined by SEM high resolution images and BET technique. The toxicity results indicate that both TiO(2) nanoparticles increase the hemolysis rate in a dose dependent way (1.6, 3.2, 4.8 μg mL(-1) ) but they do not influence superoxide anion production due to NADH addition measured by chemiluminescence. Moreover, TiO(2) nanoparticles (4.8 μg mL(-1) ) induce DNA damage and the entity of the damage is independent from the type of TiO(2) nanoparticles used. Modified comet assay (Endo III and Fpg) shows that TiO(2) oxidizes not only purine but also pyrimidine bases. In our experimental conditions, the exposure to TiO(2) nanoparticles does not affect the DNA repair system functionality. The data obtained contribute to better characterize the aqueous environmental risks linked to TiO(2) nanoparticles exposure. © 2011 Wiley Periodicals, Inc. Environ Toxicol, 2011
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
Laser Powder Bed Fusion: tailoring the microstructure of alloys for biomedical applications
No full textAdditive manufacturing (AM) is particularly attractive for biomedical applications, where complex geometries and a high degree of individualization are required. Laser powder bed fusion (LPBF) is an AM technology exploiting the action of a solid-state laser to locally melt a metal powder according to a computer aided design (CAD) model. In the present study, the EOS Cobalt Chrome SP2 (Co-Cr-Mo-W) and Ti64 (Ti6Al4V) powders were sintered by the system equipped with a Yb fiber laser. During LPBF, the Co-Cr-Mo-W metal powder undergoes total melting followed by rapid cooling, giving rise to athermal martensitic phase transformation from the high-temperature γ (fcc) phase to the low-temperature ε (hcp) phase. This produces an intricate network of thin ε-lamellae inside the γ phase matrix. After the firing cycle this structure is maintained, and a massive presence of coarse precipitates is also observed. Owing to the rapid cooling taking place during LPBF, in Ti6Al4V sintered samples only the acicular martensitic α' phase is present. The firing cycle induces the β phase formation at the α plate boundaries and this microstructure leads to reduced values of strength, with respect to those of the as-sintered samples. The highlighted behaviors show that by tuning the post-production heat treatments it is possible to tailor the microstructure and the mechanical properties
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
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