1,721,018 research outputs found
Neso Sojic (Ed.): Analytical electrogenerated chemiluminescence: from fundamentals to bioassays
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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
Electron Transfer Catalysis with Monolayer Protected Au25 Clusters
No full textAu25L18 (L = S(CH2)(2)Ph) clusters were prepared and characterized. The resulting monodisperse clusters were reacted with bis(pentafluorobenzoyl) peroxide in dichloromethane to form Au25L18+ quantitatively. The kinetics and thermodynamics of the corresponding electron transfer (ET) reactions were characterized via electrochemistry and thermochemical calculations. Au25L18+ was used in homogeneous redox catalysis experiments with a series of sym-substituted benzoyl peroxides, including the above peroxide, bis(para-cyanobenzoyl) peroxide, dibenzoyl peroxide, and bis(para-methoxybenzoyl) peroxide. Peroxide dissociative ET was catalyzed using both the Au25L18/Au25L18- and the Au25L18+/Au25L18 redox couples as redox mediators. Simulation of the CV curves led to determination of the ET rate constant (k(ET)) values for concerted dissociative ET to the peroxides. The ET free energy Delta G degrees could be estimated for all donor-acceptor combinations, leading to observation of a nice activation-driving force (log k(ET) vs. Delta G degrees) relationship. Comparison with the k(ET) obtained using a ferrocene-type donor with a formal potential similar to that of Au25L18/Au25L18- showed that the presence of the capping monolayer affects the ET rate rather significantly, which is attributed to the intrinsic nonadiabaticity of peroxide acceptors
Evidence against the Hopping Mechanism as an Important Electron Transfer Pathway for Constrained Oligopetides
No full textThe rate constant of intramolecular electron transfer through oligopeptides based on the alpha-aminoisobutyric acid residue was determined as a function of the peptide length and found to depend weakly on the donor−acceptor separation. By measuring the electron-transfer activation energy and estimating the energy gap between donor and bridge, we were able to discard the electron hopping mechanism
A fast method for the detection of irinotecan in plasma samples by combining solid phase extraction and differential pulse voltammetry
No full textIn this paper, a fast method for the detection of irinotecan (CPT-11) in plasma samples was investigated. CPT-11 is widely used in a number of chemotherapeutic treatments of several solid tumors. The method is based on the combination of a solid phase extraction and an electrochemical detection step. The extraction of CPT-11 from plasma was performed using solid phase extraction (SPE) columns and acetonitrile as eluent. The procedure included also a cleaning step to eliminate interference due to plasma endogenous compounds and the co-therapeutics 5-fluoroacil (5-FU) and folinic acid (FA). The latter are administered together with CPT-11 in the FOLFIRI regimen. The detection of CPT-11 was performed by differential pulse voltammetry at a glassy carbon electrode (GCE) in basified acetonitrile media. Under these conditions, a well-defined peak due to the oxidation of the tertiary ammine end of CPT-11, also free from interference due to main metabolites, was obtained. Calibration plots showed a good linear response with limit of detection and quantification of 1.10 × 10-7 and 3.74 × 10-7 M, respectively. The suitability of the method proposed here for clinical applications was verified by determining the concentration of CPT-11 in plasma samples of an oncological patient, collected after 30 and 180 min from the infusion of the drug. Graphical abstract
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
Metodo per la determinazione della concentrazione di 4-[(4-metil-1-piperazinil)metil]-n-(4-metil-3-{[4-(3-piridinil)-2-pirimidinil]-ammino}fenil)benzammide(imatinib) in campioni di plasma.
No full textAppropriate 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
Advanced Electrochemical and Opto-Electrochemical Biosensors for Quantitative Analysis of Disease Markers and Viruses
No full textInstrumental laboratory methods for biochemical and chemical analyses have reached a high level of reliability with excellent sensitivity and specificity. However, the complex sample preparation, the need for trained personnel as well as the use of sophisticated and expensive instrumentation still represent a drawback. Despite the indispensability of laboratory methods that guarantee excellence with regard to their analytical reliability, the need to carry out quantitative analyses for large-scale and rapid screening purposes has prompted the development of novel analytical tools, such as biosensors, capable of providing accurate and precise analytical information at low cost, ease of use and applicability for decentralized monitoring and point-of-care testing. The recent global health crisis caused by the COVID-19 pandemic has further alerted the world to the urgent need for rapid and reliable analytical devices, which are suitable for the detection of biologically active components of clinical relevancy
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