1,720,968 research outputs found
Graphene as an active material for sensors and other devices
Full text linkL'abstract è presente nell'allegato / the abstract is in the attachmen
A contamination-free electrolyte-gated organic transistors platform for high-accuracy tumor biomarker detection
Full text linkA novel biosensor platform for high-accuracy tumor biomarker detection exploiting contamination free microfluidics for increasing the signal-to-noise ratio has been successfully developed and tested. Electrolyte-gated organic Transistors (EGOT) has been employed to detect an important tumor marker, Angiopoietin-2 (Ang2). Although organic semiconductors have become popular in the last years in biosensing applications due to their many advantages, there is still a main concern about stability and selectivity. This work presents major improvement in terms of the stability and selective detection of Ang2 in the range of interest for biomedical applications. The semiconducting polymer poly[3-(5-carboxypentyl)thiophene (P3CPT) is deposited by picoliter volume control and micrometer diameter of the droplet to allow for high uniformity and repeatability from sample to sample. The optimized gold electrodes improve the detection of the minimal concentration of the target and microfluidic interfacing by a specific pattern with the desired dimensions is obtained by UV-lithography and wet etching. A microfluidics with multiple flow control allows for maintain a constant fresh solution without analytes on reference gate electrode, while another inlet and functionalized gate is used for sensing, thus reaching high stability and reproducibility. All these (four) optimizations lead to new measuring protocol and new 3D printed top cover that ensure better stabilization and repeatability of the results. The device has successfully detected Ang2 concentrations as low as 10 pM in saline, therefore demonstrating the ability of the device to detect clinically relevant concentrations
A novel electrolyte gated graphene Field Effect Transistor on Cyclo Olefin Copolymer foil
Full text linkIn this work an electrolyte gated Graphene field effect transistor (G-FET) has been developed exploiting a Hot-embossing assisted technique to transfer Single Layer Graphene (SLG) on a Cyclo Olefin Copolymer (COC) foil. An investigation on the processing and materials related effects has been carried out by a comparison with a more traditional Poly(methyl methacrylate) (PMMA) transfer approach. The fabricated G-FETs were tested as pH sensors and the electrical characteristics were investigated
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
PDAC-on-chip for in vitro modeling of stromal and pancreatic cancer cells crosstalk
Full text linkPancreatic ductal adenocarcinoma (PDAC) mainly develops in the head of the pancreas, within the acinoductal unit composed of acinar and ductal cells surrounded by pancreatic stellate cells (PSCs). PSCs strongly influence the tumor microenvironment by triggering an intense stromal deposition, which plays a key role in tumor progression and limits drug perfusion. We have developed a microfluidic in vitro model recreating the in vivo tumor-stroma crosstalk to replicate the steps of PDAC evolution towards the establishment of an efficient in vitro platform for innovative therapy validation. The multilayer PDAC-on-chip was designed to culture the PDAC cells and the PSCs embedded in a type I collagen gel in the top and bottom layers, respectively. The presence of a biomimetic nanofibrous membrane in the middle of the chip permits the control of interactions between the two cell lines and the easy analysis of the effects of the crosstalk on cell behavior. First, the PDAC-stromal cell relationship was evaluated under co-culture conditions on 24-well inserts including the PCL/Gel electrospun membrane. This simplified model shows that human fibroblasts change their morphology and secrete larger amounts of IL-6 cytokines in the presence of tumor cells, confirming the activation of stromal cells under co-culture. Then, the PDAC-on-chip system was validated by demonstrating that human fibroblasts seeded in a 3D collagen matrix in the bottom microchannel also change to a myofibroblast-like shape with increased expression of α-SMA and secrete larger amounts of IL-6 cytokines. This microfluidic system is suitable for the evaluation of drug efficacy and serves as a powerful tool for understanding the early evolution steps of PDAC
- …
