1,721,087 research outputs found
Scanning electrochemical microscopy: diffusion controlled approach curves for conical AFM-SECM tips
No full textThe diffusion controlled response of conical AFM-SECM probes is presented. Accurate expressions are given which describe the dependence of the probe current on the tip radius and aspect ratio, insulating sheath radius and tip–substrate distance for positive feedback and hindered diffusion. A procedure is proposed to determine the tip dimensions from the experimental approach curves
Atomic force microscopy-scanning electrochemical microscopy: influence of tip geometry and insulation defects on diffusion controlled currents at conical electrodes
No full textNumerical simulations were performed to predict the amperometric response of conical electrodes used as atomic force microscopy-scanning electrochemical microscopy (AFM-SECM) probes. A simple general expression was derived which predicts their steady state limiting current as a function of their insulation sheath thickness and cone aspect ratio. Simulated currents were successfully compared with experimental currents. Geometrical parameters such as insulation angle and tip bluntness were then studied to determine their effect on the limiting current. Typical tip defects were also modeled using 3D simulations, and their influence on the current was quantified. Although obtained for SECM-AFM probes, these results are directly applicable to conical micro- and nanoelectrodes.<br/
Electrochemical current-sensing atomic force microscopy in conductive solutions
Full text linkInsulated atomic force microscopy probes carrying gold conductive tips were fabricated and employed as bifunctional force and current sensors in electrolyte solutions under electrochemical potential control. The application of the probes for current-sensing imaging, force and current-distance spectroscopy as well as scanning electrochemical microscopy experiments was demonstrated
Structure Formation and Annealing of Isophthalic Acid at the Electrochemical Au(111)/Electrolyte Interface
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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
Interfacial electrochemistry and in situ SEIRAS investigations of self-assembled organic monolayers on Au/electrolyte interfaces
No full textElectrified solid/liquid interfaces offer unique opportunities for the fabrication and characterization of 2D supramolecular nanostructures. The combination of macroscopic electrochemical methods with structure sensitive techniques, such as scanning probe microscopy (SPM) or vibrational spectroscopy enables the development of a detailed knowledge on structure and functionality of the created molecular assemblies. In the present dissertation, the steady state and dynamic properties of self-assembled adlayers of trimesic acid and thioalkylviologens were investigated on gold/electrolyte interfaces employing surface enhanced IR absorbance spectroscopy (SEIRAS) in combination with various electrochemical methods. The double layer properties of the Au/aqueous electrolyte interface were investigated first for massive Au(111) single crystal electrodes and Au(111-20 nm) film electrodes in contact with 0.1 M _{2}SO_{4}_{4}$. Cyclic voltammetry revealed that the response of the film electrodes resembles that of a massive Au (111) electrode with a low step density. The potential-dependent adsorption of anions and interfacial water was investigated in detail by in situ SEIRAS. As the second topic, the adsorption and phase formation of trimesic acid (TMA) on Au(111) and Au(111-20 nm) electrodes were comprehensively investigated by electrochemical techniques, scanning tunneling microscopy and SEIRAS. Depending on the applied electrode potential, TMA molecules form several highly ordered 2D adlayers: two physisorbed phases, one characterized by a hexagonal honeycomb pattern and the other by close-packed linear-dimers of planar oriented molecules; and one stripe-like chemisorbed adlayer of perpendicularly oriented molecules. Weakly hydrogen-bonded, strongly hydrogen-bonded and isolated water species are coadsorbed. The potential-induced formation of chemisorbed TMA starts with a fast orientation change from planar, physisorbed molecules to tilted and/or perpendicular in a disordered chemisorbed phase. Subsequently, the chemisorbed TMA molecules align slowly into the highly ordered stripe-like structure. Both substrate/adsorbate and intermolecular hydrogen-bonding interactions are strongly dependent on the electrode potentia
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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