1,720,963 research outputs found
Precise Positioning of Particles in Microwells within Horizontal DEP Cages
No full textAn efficient method to trap and analyze particles
avoiding excessive electric field strength is to use negative
dielectrophoretic cages, where particles find stability in the
electric field minimum. We present a novel structure where
particles are trapped and forced to interact within
microwells opened at top and bottom sides by creating a
cylindrical negative dielectrophoretic cage. This approach
provides a controlled alignment of the particles along a
predefined axis. An array of microwells is built by drilling
through holes with a diameter of 150 μm on a flexible
printed circuit board with two Cu/Au layers separated by
one polyimide layer, providing a cheap and disposable
device. Levitation of one or two polystyrene beads with a
diameter of 25 μm in DI-water was experimented
confirming the positioning predicted by physical
simulations. Vertical position of the particles as a function
of the amplitude of polarization signals was extracted from
simulations and confirmed by experimental results
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Two-step approach for the nanofabrication of highly ordered ultra-long porous gold nanowires with an adjustable porosity for SERS-based sensors
No full textRecently, nanoporous gold has been pointed out as a promising candidate for the development of SERS-based sensors for the detection of environmental toxins and small molecules [1]. One way to improve the detection ability of such sensors is by engineering the porosity and shape of nanoporous material. In this work we report on a versatile two-step approach for the synthesis of porous nanowires involving plasma deposition of gold-copper alloy on a nanograted substrate followed by a selective electrochemical etching. The relevance of the approach is its ability to prepare highly ordered ultra-long porous gold nanowires with an adjustable porosity and a length up to the macroscale. The resulting gold porous nanowire exhibits a very high roughness and high specific surface area suitable for highly sensitive detection of small molecules by SERS. References: [1] L. Zhang, H. Chang, A. Hirata, H. Wu,Q.-K. Xue and M. Chen, ACS Nano 7, 4595 (2013
Innovative gold nanoparticle patterning and selective metallization
Get PDFWe present a simple procedure to selectively deposit gold nanoparticles using pure water. It enables patterning of nanoparticle monolayers with a remarkably high degree of selectivity on flat as well as microstructured oxide surfaces. We demonstrate that water molecules form a thin capping layer on exposed thiol molecules within mercaptan self-assembled layers. This reversible capping of water molecules locally deactivates the thiol groups, therewith inhibiting the binding of metallic gold nanoparticles to these specific areas. In addition, we show that this amazing role of water molecules can be used to selectively metallize the patterned gold nanoparticle arrays. Employing an electroless seeded growth process, the isolated seeds are enlarged past the percolation threshold to deposit conducting metal layers.</p
Directional wetting on chemically stripe-patterned surfaces:Static droplet shapes and dynamic motion on gradients
Get PDFThe directional wetting characteristics of droplets on chemically defined stripe-patterned anisotropic substrates are briefly reviewed. The static droplet shape as well as the observed contact angles exhibit unique scaling behavior as a function of the macroscopic wettability, as arising from patterns consisting of alternating hy-drophilic and hydrophobic stripes. In addition, the motion of liquid from surface regions with low macroscopic wettability towards more wetting areas is described. Linear patterns are presented, which induce liquid movement along the chemically defined stripes giving rise to a macroscopic gradient in surface energy. Finally, we show that lattice Boltzmann modeling enables semrquantitatively accurate simulation of the experimental observations.</p
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