1,720,965 research outputs found
Polymer Microfabrication Modules for Cytostretch Organ-on-chip Applications
No full textThe use of conventional biological assay tools, such as Petri dish, has hindered the drug discovery studies ineffective and time-consuming. To cope with this problem, organ-on-chip (OOC) devices have been developed. Modeling organ functionality, topography, and pathology, OOC devices are expected to pave the way the drug discovery processes. Recently, a novel OOC fabricated using integrated circuit (IC) technology was introduced. It is called Cytostretch. It allows for mechanical stimulation of the cultured cardiomyocytes by delivering a certain pressure to the backside of the membrane to replicate a beating heart. The presence of micro-electrode arrays (MEAs) in the device enables to characterize the field potentials of the cells for certain strains. Meanwhile, topography features such as grooves were implemented to induce cell alignment.During the development of this device, two crucial problems were noticed. The first problem is the poor adhesion of the polyimide (PI) to the polydimethylsiloxane (PDMS) membrane. The PI functions function as insulation layers and provide mechanical integrity to the MEAs. Therefore, the good adhesion of these layers to the membrane is a must. Unfortunately, the recent fabrication results showed that the adhesion of the PI tracks to the PDMS membrane was poor. The second problem is the PDMS membrane itself. Naturally, PDMS can take up molecules, which is problematic in the drug screening studies, since it can compromise the bio-assay results. Furthermore, the presence of silicon backbone in the PDMS structure can also be problematic for the PDMS patterning. Many reports demonstrated that PDMS could not be dry-etched without any residues. The residues were also found in the previous Cytostretch fabrication after the PDMS patterning to form bondpad openings.In this report, the solutions of these two problems are demonstrated. In terms of the PI-PDMS adhesion problem, the silicon carbide-silicon dioxide (SiC-SiO2) bilayer was proposed. In the previous studies, the use of this bilayer has been reported to promote the PI-PDMS adhesion in neural prosthesis devices and flexible body patches. In this work, the SiC-SiO2 fabrication was integrated into the Cytostretch fabrication using plasma-enhanced vapor deposition (PECVD). The immersion tests and the cyclic loading tests showed that the device with the SiC-SiO2 bilayer has an excellent PI-PDMS adhesion.To replace the PDMS membrane, another elastic polymer, polybutadiene rubber (PBR), was studied. Different from the PDMS, the PBR is purely organic without any silicon backbones on its structure. Thus, it is hypothesized that the PBR can be processed more easily than the PDMS. In this work, the patterning of the PBR was elaborated. The PBR patterning experiments began using a bare silicon wafer. The PBR patterning with a wet-etched titanium hard etch mask demonstrated a good anisotropic etching profile. Based on this result, the PBR patterning module was integrated into the Cytostretch fabrication. The bondpad openings in the PBR membrane were also successfully patterned with an anisotropic etching profile. Unfortunately, this successful result was also followed by some issues regarding the non-uniform PBR thickness and the results caused by the errors during the fabrication.Biomedical Engineering | Bioelectronic
Computational analysis of soft polymer lattices for 3D wound dressing materials / Muhammad Hanif Nadhif …[et al.]
Get PDFOne of the wound treatments was negative pressure wound therapy (NPWT), which used wound dressings on the wound bed to ameliorate the wound healing. Unfortunately, most wound dressings were two dimensional (2D), lacking the ability to cover severe wounds with a straightforward procedure. The sheets needed to be stacked following the wound curvature, which might be problematic since improper stacking could hinder the wound healing. Regarding the mentioned problems, our group develop 3D wound dressings, which are made using 3D printers. The wound dressings are made of polycaprolactone (PCL), polyurethane (PU), and polyvinyl alcohol (PVA). As the initial stage, the mechanical integrity of the soft polymers was investigated under uniaxial tensile and uniaxial compressive stress using computational methods. The polymers were defined as 3D lattices following the dimension of existing wound dressings. Based on the simulation results of displacement and von Mises stress, the three polymers are mechanically safe to be used as wound dressing materials
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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