1,720,977 research outputs found
Degradation of Organic Dye Congo Red by Heterogeneous Solar Photocatalysis with Bi2S3, Bi2S3/TiO2, and Bi2S3/ZnO Thin Films
No full textIn this work, bismuth sulfide (Bi2S3) thin films were deposited by a chemical bath deposition
(CBD) technique (called soft chemistry), while titanium dioxide (TiO2) nanoparticles were
synthesized by sol–gel and zinc oxide (ZnO) nanoparticles were extracted from alkaline batteries.
The resulting nanoparticles were then deposited on the Bi2S3 thin films by spin coating at 1000 rpm
for 60 s each layer to create heterojunctions of Bi2S3/ZnO and Bi2S3/TiO2. These materials were
characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive
X-ray spectroscopy (EDX). The optical and contact angle analyses were undertaken by UV–Vis
spectroscopy and a contact microscopy angle meter, respectively. The calculated band gap values
were found to be between 1.9 eV and 2.45 eV. The Bi2S3 presented an orthorhombic structure, the
TiO2 nanoparticles presented an anatase structure, and the ZnO nanoparticles presented a wurtzite
hexagonal crystal structure. Furthermore, heterogeneous solar photocatalysis was performed using
the Bi2S3, Bi2S3/ZnO, and Bi2S3/TiO2 thin film combinations, which resulted in the degradation of
Congo red increasing from 8.89% to 30.80% after a 30 min exposure to sunlight
Silver nanoclusters stabilized with PVP-BSA conjugate: Optical properties approach
No full textThe objective of this research was to synthesize fluorescent silver nanoclusters (NC Ag-BSA/PVP) using polyvinylpyrrolidone polymer (PVP) as a stabilizer in conjunction with bovine serum albumin protein (BSA). The nanoclusters were prepared using a wet chemistry reduction technique with two distinctive pathways: the addition of PVP after BSA and the addition of PVP after the metal precursor. The optical properties of the materials were studied in samples with different BSA/PVP molar ratios and varying amounts of metal/reductant. The impact of protein and polymer amounts on fluorescence was determined. The materials were characterized using X-ray diffraction (XRD), infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray energy dispersive spectroscopy (EDS), dynamic light scattering (DLS), fluorescence spectroscopy, and UV-Vis-NIR spectroscopy.
It was observed that increasing the BSA/PVP ratio resulted in higher fluorescence intensity at λ = 450 nm and a decrease at λ = 600 nm. Regarding the metal/reductant ratio, the amount of metal ions impacted the intensity obtained at λ = 600 nm. The experiments revealed that BSA had the largest effect on fluorescence intensity at λ = 450 nm, with little effect on fluorescence intensity regardless of the amount of polymer used. Due to its one-step synthesis and favorable reaction conditions, the NC Ag-BSA/PVP obtained under the proposed methodology holds promise as an optical marker material. The use of the stabilizing duo BSA-PVP, as well as the proposed amounts in this research, serves as a precedent for developing new experimental syntheses of colloidal nanoparticles
Synthesis of nanostructured Nickel compounds on conductive metallicsubstrates
No full textNickel hydroxide, oxide, and sulfide films were synthesized on conductive Ni metallic substrates by solidvapor reactions, calcination and hydrothermal methods. The synthesized films were characterized by
XRD, XPS, FE-SEM, UV–Vis Spectroscopy and Cyclic Voltammetry (CV). The morphological analyses of
Ni(OH)2 and NiO films showed flower-like nanostructures with thicknesses from 20 to 40 nm; meanwhile
the NiS films exhibits nano-granular morphology. All films showed high optical reflectance in the visible
region and a sharp absorption edge below 400 nm. The specific capacitance of the Nickel compound
ranges from 134 to 311 mF cm 2 (at 20 mV s 1) suggesting potential as conductive electrodes for energy
storage and electrochemical conversion cells
Study of indium tin oxide–MoS2 interface by atom probe tomography
No full textThe molybdenum disulfide (MoS2) and indium tin oxide (ITO) interface were studied by atom probe tomography (APT). Raman spectroscopy, scanning electron microscopy, and grazingincidence x-ray diffraction measurements were performed as complementary characterization. Results confirm that nanowires plated shape with the 〈110〉-orientation are aligned perpendicular to the ITO film with principal reflections at (002), (100), (101), (201), and Raman spectroscopy vibrational modes at E 2g at 378 cm and A1g at 407 cm correspond to 2H-MoS2. APT reveals MoS , MoS as predominant evaporated
molecular ions on the sample, indicating no significant diffusion/segregation of Mo or S species within the ITO layer
Photocatalytical degradation of methyl orange (MO) using ZnO nanoparticles from alkaline wasted batteries. The effect of the MO, catalyst, and organic loads
No full textThe photocatalytic degradation of methyl orange (MO) using ZnO nanoparticles is reported. NPs in the range of 40-60 nm were obtained from wasted alkaline batteries anodes. The effect of the MO concentration and the catalyst load were analyzed finding that NPs exhibited similar photocatalytic activities than those reported for ZnO-NPs obtained from pure sources when similar conditions are used. The effect of the organic loads (COD from 60 to 900 ppm) in the catalyst efficiency was studied detecting that COD:60 ppm does not affect the ZnO photocatalytical properties. However, high COD loads (600-900 ppm) make the degradation efficiency almost null
Effect of V2O5 coatings on NMC 111 battery cathode materials in aqueous process
No full textIn this study, we focused on the effect of different percentages of coating on the chemical stability of NMC 111. Stability and leaching studies were conducted in solutions at varying pH levels to quantify the influence of coating percentage and exposure conditions on chemical stability. Our findings indicate effective protection of NMC 111. The slurries containing coated particles remain stable across acidic, neutral, and basic pH ranges. This observation provides a broad aqueous processing window for coated NMC 111, preventing lithium-ion leaching. For the uncoated samples, the measured pH consistently remained in the basic range, regardless of the initial pH, indicating a strong reaction between NMC 111 and water that leads to the formation of hydroxides. I The thicker coatings (3% and 4% by weight) are particularly effective in reducing lithium leaching. XRD analysis suggests that the coating helps minimize cation mixing. XPS, TEM, and SEM-EDS morphological characterization were performed to confirm the presence of the coating on the surface of the samples. Additionally, the coating percentage and its effect on charge transfer resistance in sintered samples were discussed and analyzed using EIS with Ag as an ion-blocking agent
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
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