1,721,146 research outputs found
Different corrosive effects on hydroxyapatite nanocrystals and amine fluoride-based mouthwashes on dental titanium brackets: a comparative in vitro study
Full text linkTitanium plates treated in vitro with a mouthwash containing amine fluoride (100 ppm F-) and another containing zinc-substituted carbonate-hydroxyapatite have been analyzed by scanning electron microscopy and atomic force microscopy to evaluate the modification of the surface roughness induced by treatment with these two different mouthwashes. The treatment with F--based mouthwash produces a roughness characterized by higher peaks and deeper valleys in the streaks on the titanium bracket surface compared with those observed in the reference polished titanium plates. This effect causes a mechanical weakness in the metallic dental implant causing bacterial growth and therefore promotes infection and prosthesis contamination. However, the in vitro treatment with a mouthwash containing zinc-substituted carbonate-hydroxyapatite reduced the surface roughness by filling the streaks with an apatitic phase. This treatment counteracts the surface oxidative process that can affect the mechanical behavior of the titanium dental implant, which inhibits the bacterial growth contaminating prostheses
Electrochemical and Surface Characterization of Dense Monolayers Grafted on ITO and Si/SiO2 Surfaces via Tetra (tert‐Butoxy) Tin Linker
No full textIndium tin oxide (ITO) and silicon with a thermally grown SiO2 layer (Si/SiO2) substrates have been functionalized by ferrocene bound through Sn(O)x (x=2 or 3) linkers preliminarly grafted on the surface by reaction of the terminal hydroxyl groups with tetra(tert-butoxy)tin. The two steps modification of the surface was carried out by chemical vapour deposition metathesis reaction producing a self-assembled monolayer of ferrocene. The ITO and Si/SiO2 thus functionalized have been characterized by voltammetric, amperometric, electrochemical impedance spectroscopy and scanning probe microscopy techniques which assessed the formation of a stable and rather compact covalently bound ferrocenyl monolayer with improved electron transfer properties
Fluorinated Fullerenes: Sources of Donor-Acceptor Dyads with [18]Trannulene Acceptors for Energy- and Electron-Transfer Reactions
No full textLocal desorption of thiols by scanning electrochemical microscopy: patterning and tuning the reactivity of self-assembled monolayers
No full textSelf-assembled monolayers (SAMs) are widely
used in the field of nanotechnologies and (bio)sensors. The
monolayer surface properties are tailored by employing several
techniques. A large set of SAM post-modification routes
are commonly performed to adapt them to a variety of nanotechnological
and bio-technological studies as well as to several
bio-sensoristic applications. Here, we report a procedure
to locally modify SAMs by electrochemical desorption of
alkanethiols in order to create microsized spots of bare gold
area without affecting the surrounding monolayer stability.
The tip of the scanning electrochemical microscope (SECM)
was employed to draw microstructured pattern according to a
defined geometry. The time stability of the pattern was also
tested. Furthermore, the patterned surface was postfunctionalized
using the same alkanethiol or a ferroceneterminated
thiol, in order to tune the surface reactivity of the
microstructure. The local surface properties, including reactivity
and electron transfer kinetics toward redox mediator
reduction, were characterized by SECM
Local desorption of thiols by scanning electrochemical microscopy: patterning and tuning the reactivity of self-assembled monolayers
No full textSelf-assembled monolayers (SAMs) are widely used in the field of nanotechnologies and (bio)sensors. The monolayer surface properties are tailored by employing several techniques. A large set of SAM post-modification routes are commonly performed to adapt them to a variety of nano-technological and bio-technological studies as well as to several bio-sensoristic applications. Here, we report a procedure to locally modify SAMs by electrochemical desorption of alkanethiols in order to create microsized spots of bare gold area without affecting the surrounding monolayer stability. The tip of the scanning electrochemical microscope (SECM) was employed to draw microstructured pattern according to a defined geometry. The time stability of the pattern was also tested. Furthermore, the patterned surface was post-functionalized using the same alkanethiol or a ferrocene-terminated thiol, in order to tune the surface reactivity of the microstructure. The local surface properties, including reactivity and electron transfer kinetics toward redox mediator reduction, were characterized by SECM
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
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