1,720,955 research outputs found
Electrochemical sensing of aerobic marine bacterial biofilms and the influence of nitric oxide attachment control
No full textAn attractive alternative to ineffective and inefficient biocide dosing strategies for seawater piping systems would be to monitor, quantitatively evaluate and then induce biofilm disruption when necessary using an environmentally friendly biocide. The aim of the present Ostl and EPSRC funded project is to (i) sense for the presence of bacterial biofilms on metallic surfaces within seawater handling systems (e.g. heat exchangers, pipework, pumps and valves) by deploying a sensor technology to ultimately disrupt biofilms matrix and to (ii) qualitatively and quantitatively assess the extent of bacterial fouling. An electrochemical sensor using a 0.2 mm diameter gold electrode was characterised in abiotic and biotic media within a modified continuous culture flow cell under a controlled laboratory environment. Herein, electrochemical measurements by imposing electrical cathodic polarisations have demonstrated enhancement of the oxygen reduction reaction within aerobic bacterial biofilms. Importantly, electrochemical impedance spectroscopy at open circuit potential, i. e. without electrical imposed polarisation, was successfully employed to monitor initial bacterial biofilms growth and extent. An important parameter of the sensor response (capacitive component) can provide insight into quantitative evaluation of the interface, where for the first time in situ quantifiable EIS data were in good agreement with ex situ confocal microscopy analyses. Consequently, a relationship for the surface charge density (capacitive component I estimated number of sessile bacterial population) has outlined its potential use for in-service conditions. Uniquely, the electrochemical performances of a 72 h-old biofilmed gold surface dosed with nanomolar concentration; 500 nM, of the nitric oxide donor sodium nitroprusside were presented. Corroborative confocal microscopy studies have revealed effective and efficient dispersal of aerobic bacterial biofilms exposed to nitric oxide. Overall, this unique qualitative and quantitative bacterial biofilm investigation utilising a modified once through flow cell, i.e. combining microbiological and engineering expertise, represents an important first step in controlling of marine biofouling within seawater piping systems. Gold multi-microelectrode arrays located on likely biofouling positions within the seawater piping systems should be used for enhanced effectiveness of the biofilm sensing I disruption strategy.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Electrochemical sensing and characterization of aerobic marine bacterial biofilms on gold electrode surfaces
Full text linkReliable and accurate in situ sensors capable of detecting and quantifying troublesome marine biofilms on metallic surfaces are increasingly necessary. A 0.2 mm diameter gold electrochemical sensor was fully characterised using cyclic voltammetry in abiotic and biotic artificial seawater media within a continuous culture flow cell to detect the growth and development of an aerobic Pseudoalteromonas sp. biofilm. Deconvolution of the abiotic and biotic responses enable the constituent extracellular electron transfer and biofilm responses to be resolved. Differentiation of enhanced oxygen reduction kinetics within the aerobic bacterial biofilm are linked to enzyme and redox mediator activitie
Monitoring Aerobic Marine Bacterial Biofilms on Gold Electrode Surfaces and the Influence of Nitric Oxide Attachment Control
Full text linkDetection of aerobic
marine bacterial biofilms using
electrochemical
impedance spectroscopy has been done to monitor the interfacial response
of Pseudoalteromonas sp. NCIMB 2021
attachment and growth in order to identify characteristic events on
a 0.2 mm diameter gold electrode surface. Uniquely, the applicability
of surface charge density has been proven to be valuable in determining
biofilm attachment and cell enumeration over a 72 h duration on a
gold surface within a modified continuous culture flow cell (a controlled
low laminar flow regime with Reynolds number ≈ 1). In addition,
biofilm dispersal has been evaluated using 500 nM sodium nitroprusside,
a nitric oxide donor (nitric oxide is important for the regulation
of several diverse biological processes). Ex situ confocal microscopy
studies have been performed to confirm biofilm coverage and morphology,
plus the determination and quantification of the nitric oxide biofilm
dispersal effects. Overall, the capability of the sensor to electrochemically
detect the presence of initial bacterial biofilm formation and extent
has been established and shown to have potential for real-time biofilm
monitoring
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
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
- …
