1,720,964 research outputs found
Laser Powder Bed Fusion (L-PBF) of high-strength Aluminum alloys
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Enhancing Electrochemical Sensor Performance: Studies of Electrodes Tailored with ZnO/ZnFe2O4 Nanoparticles
Get PDFSpinel metal oxides possess excellent magnetic, electrical, and optical properties. They take AB2O4 (face centered cubic) form with oxygen anions providing tetrahedral (Td) and octahedral (Oh) sites for A+2 and B+3 cations. Spinel can have a normal, inverse, or mixed form based on the occupancy of different cations in Td and Oh sites. The peculiarity of the spinel crystal structure is that its composition can be easily modified without affecting the crystal structure based on the type of cation. The type of cation in the composition defines if the spinel has a normal or inverse form [1]. Based on these premises, we have already synthesized ZnxNi1-xFe2O4 (x =0, 0.2, 0.4, 0.6, 0.8, 1) nanomaterials achieving a clear gradual transition from inverse (x=0) to normal (x=1) spinel. Synthesized nanomaterials were employed as mediators in electron transfer between the screen-printed carbon working electrode and paracetamol to understand the effect of chemical composition and crystal structure on the electron transfer at the electrochemical interface [1]. Normal spinel ZnFe2O4 was found to be the best nanomaterial in terms of sensitivity and kinetic rate constant. In further works, with the aim to understand the effect of ionic radii on sensitivity and electron transfer rate constant in electrochemical sensing of paracetamol, we have focused on the normal spinel structure and modified the composition by varying the concentration of Fe3+ with Cr3+ and Bi3+ [2,3]. This study also proved that the normal spinel ZnFe2O4 has the highest sensitivity and electron transfer rate constant towards paracetamol sensing. In this work, we will present the synergic effect that can be obtained by interfacing ZnFe2O4 with ZnO nanomaterials by tuning the band gap of the heterogeneous structure. The aim is to understand the effect of band gap on sensitivity and electron transfer rate constant in electrochemical sensing. ZnFe2O4, ZnO, and ZnO/ZnFe2O4 nanomaterials are synthesized by a simple, single step auto combustion technique using the respective metal nitrates as precursors. Nanomaterial morphology and particles size are investigated by scanning electron microscopy. X-ray diffraction technique is employed to analyze the crystal structure and identify different phases in the newly synthesized materials. Then, commercially available screen-printed carbon electrodes with carbon working electrode and carbon counter electrodes are used for the electrochemical measurements in combination with an external double junction Ag/AgCl as a reference electrode. The synthesized nanomaterials are mixed with 1-butanol and a 5 μL solution is used to modify the surface of the carbon working electrode to mediate the redox reactions between the carbon surface and the molecule of interest. Primarily the sensors are characterized using cyclic voltammetry with ferri/ferrocyanide redox couple as a probe molecule. Improvement in sensitivity is observed for ZnFe2O4 (8.85 ± 0.50 μA/mM), ZnO (8.50 ± 0.30 μA/mM), and ZnO/ZnFe2O4 (8.22 ± 0.16 μA/mM) sensors compared to the bare carbon one (6.30 ± 0.40 μA/mM). By performing cyclic voltammetry at different scan rates (ν) from 25 to 125 mV/s, a good linearity of redox currents with respect to v0.5 is observed and redox peak positions are varying linearly with ln(ν). Peak-to-peak separation (ΔEp) is reduced for ZnO/ZnFe2O4 sensors compared to the carbon one. All these results suggest a faster electron transfer at the interface when the modified electrodes are used. Laviron model is employed to calculate the electron transfer rate coefficient and constant. The rate constant for ZnFe2O4 (41.8 ± 2.6 ms-1), ZnO (46.0 ± 4.0 ms-1), and ZnO/ZnFe2O4 (33.1 ± 4.5 ms-1) sensors is 3 to 5 times higher as compared to the bare carbon one (9.97 ± 0.78 ms-1). We are currently studying the potential application of ZnO/ZnFe2O4 nanomaterials in electrochemical sensing of small molecules relevant in biomedical field (dissolved oxygen, pH) and pharmaceutical drugs (paracetamol) to assess the potential for their use in different clinical settings. References: M.Madagalam et al., “Unraveling the effect of chemical and structural composition of ZnxNi1-xFe2O4 on the electron transfer at the electrochemical interface,” Small Struct. 2023, 2300163. M.Madagalam et al., “ZnMxFe2-xO4 (M=Cr, Bi) Nanoparticles-modified electrochemical sensors: Effect on sensitivity and first-order kinetic rate constant,” 2023 IEEE BioSensors Conference (BioSensors), London, United Kingdom, 2023, pp. 1-4, doi: 10.1109/BioSensors58001.2023.10280910. M. Madagalam et al., "ZnCr2-xFexO4 Nanoparticles-Modified Electrochemical Sensors: A Comparative Study," 2023 IEEE SENSORS, Vienna, Austria, 2023, pp. 01-04, doi: 10.1109/SENSORS56945.2023.10325135. Figure 1SCI-STI-S
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
Unveiling the effect of Bi in ZnFe2O4 nanoparticles in electrochemical sensors
Get PDFThis work investigates the effect of the inclusion of Bi3+ ions in ZnFe2O4 nanoparticles on electron transfer at the electrochemical interface. ZnBixFe2-xO4 (x = 0, 0.5, 1, 2) nanomaterials are synthesized and the impact of Bi3+ ions on the chemical features of ZnFe2O4 nanoparticles is studied by using different materials’ characterization techniques. The effect of the change in the chemical composition of ZnFe2O4 nanoparticles on the electrochemical sensing performance is extensively studied and correlated with the electrochemical sensitivity and kinetic rate constant. Screen-printed electrodes functionalized with ZnBixFe2-xO4 nanomaterials have an excellent enhancement of electrochemical sensing performance towards paracetamol, as a test molecule, compared to the carbon electrodes. The highest sensitivity (37.8 ± 0.2 μA/mM) and the best kinetic rate constant (13.1 ± 2.8 ms−1) are achieved by the ZnFe2O4 sensor, while the ZnBi2O4 sensor achieved a sensitivity of (23.5 ± 0.6) μA/mM with a kinetic rate constant of (0.45 ± 0.16) ms−1. The ZnFe2O4 sensor is found to have a direct electron transfer, whereas the other sensors participate in a surface state-mediated electron transfer at the electrochemical interface. This research shows a clear path to the potential applications of spinel oxide-based electrochemical sensors for specific drugs or molecules detection
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
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