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41.
Electronic and Structural Properties of Highly Aluminum Ion Doped TiO2 Nanoparticles: A Combined Experimental and Theoretical Study 下载免费PDF全文
Desireé M. de los Santos Teresa Aguilar Dr. Antonio Sánchez‐Coronilla Dr. Javier Navas Dr. Norge Cruz Hernández Dr. Rodrigo Alcántara Dr. Concha Fernández‐Lorenzo Prof.Dr. Joaquín Martín‐Calleja 《Chemphyschem》2014,15(11):2267-2280
This study presents the experimental and theoretical study of highly internally Al‐doped TiO2 nanoparticles. Two synthesis methods were used and detailed characterization was performed. There were differences in the doping and the crystallinity, but the nanoparticles synthesized with the different methods share common features. Anatase to rutile transformation occurred at higher temperatures with Al doping. X‐ray photoelectron spectroscopy showed the generation of oxygen vacancies, which is an interesting feature in photocatalysis. In turn, the band‐gap energy and the valence band did not change appreciably. Periodic density functional calculations were performed to model the experimentally doped structures, the formation of the oxygen vacancies, and the band gap. Calculation of the density of states confirmed the experimental band‐gap energies. The theoretical results confirmed the presence of Ti4+ and Al3+. The charge density study and electron localization function analysis indicated that the inclusion of Al in the anatase structure resulted in a strengthening of the Ti?O bonds around the vacancy. 相似文献
42.
Florian A. Mann Niklas Herrmann Felipe Opazo Sebastian Kruss 《Angewandte Chemie (International ed. in English)》2020,59(40):17732-17738
Single‐walled carbon nanotubes (SWCNTs) are a 1D nanomaterial that shows fluorescence in the near‐infrared (NIR, >800 nm). In the past, covalent chemistry was less explored to functionalize SWCNTs as it impairs NIR emission. However, certain sp3 defects (quantum defects) in the carbon lattice have emerged that preserve NIR fluorescence and even introduce a new, red‐shifted emission peak. Here, we report on quantum defects, introduced using light‐driven diazonium chemistry, that serve as anchor points for peptides and proteins. We show that maleimide anchors allow conjugation of cysteine‐containing proteins such as a GFP‐binding nanobody. In addition, an Fmoc‐protected phenylalanine defect serves as a starting point for conjugation of visible fluorophores to create multicolor SWCNTs and in situ peptide synthesis directly on the nanotube. Therefore, these quantum defects are a versatile platform to tailor both the nanotube's photophysical properties as well as their surface chemistry. 相似文献
43.
44.
Rosa M. Rodriguez-Jasso Solange I. Mussatto Lorenzo Pastrana Cristóbal N. Aguilar José A. Teixeira 《Chemical Papers》2014,68(2):203-209
Sulphated polysaccharides (SP) were extracted from Fucus vesiculosus seaweed by using two different hydrothermal processes: microwave-assisted extraction (MAE) and autohydrolysis (AH). The extraction yields, chemical composition, and antioxidant activity of the polysaccharides extracted were determined and compared. Although both processes afforded SP with similar yields (18.2 mass % and 16.5 mass %, for MAE and AH, respectively) and l-fucose as the main monosaccharide, the heterogeneous structure of the polysaccharide recovered was significantly affected by the AH process. The SP obtained by MAE contained 53.8 mole % of fucose, 35.3 mole % of xylose, and 10.8 mole % of galactose; while the SP obtained by AH was composed of 76.8 mole % of fucose and 23.2 mole % of galactose. Both samples presented comparable values of antioxidant activity by the di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium (2,2-diphenyl-1-picrylhydrazyl, DPPH), 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS), and lipid oxidation inhibition methods, but the polysaccharide obtained by AH exhibited a higher antioxidant potential by the differential pulse voltammetry technique. This study demonstrates that the chemical composition and antioxidant activity of SP obtained from F. vesiculosus vary according to the process used for their extraction. However, the SP obtained by MAE or AH both have the potential for use as natural antioxidants in industrial applications. 相似文献
45.
Multi‐responses Methodology Applied in the Electroanalytical Determination of Hair Dye by Using Printed Carbon Electrode Modified with Graphene 下载免费PDF全文
Felipe Fantinato Hudari Sergio Luis Costa Ferreira Maria Valnice Boldrin Zanoni 《Electroanalysis》2016,28(5):1085-1092
This paper describes a rapid and sensitive method for determination of the hair dye Basic Blue 41 in wastewater samples using screen‐printed carbon electrodes modified with graphene (SPCE/Gr). The method is based on the reversible reduction of azo groups of the dye at potential of ?0.23 V/?0.26 V, where both the anodic and cathodic currents increased 1,300 % when compared to screen‐printed carbon (SPCE) and glassy carbon electrodes (GCE). The optimization of a square wave voltammetric method was performed by means of 23 factorial design, Doehlert matrix and multi‐response assays, and the best parameters were: frequency (54.8 Hz), step potential (6 mV), pulse amplitude (43.7 mV) and pH 4.5. The analytical curve was constructed from 3.00×10?8 to 2.01×10?6 mol L?1, with detection and quantification limits of 5.00×10?9 and 1.70×10?8 mol L?1, respectively. The repeatability of the method evaluated for 10 consecutive measurements at concentrations of 1.70×10?7 mol L?1 and 1.70×10?6 mol L?1, showed relative standard deviation of 3.56 and 0.57 %, respectively. The sensor based in SPCE/Gr was successfully applied in wastewater samples collected from a drinking water treatment plant and validated by comparison with HPLC‐DAD method with good accuracy. 相似文献
46.
Wavelet processing and digital interferometric contrast to improve reconstructions from X‐ray Gabor holograms 下载免费PDF全文
Juan C. Aguilar Masaki Misawa Kiyofumi Matsuda Yoshio Suzuki Akihisa Takeuchi Masato Yasumoto 《Journal of synchrotron radiation》2018,25(3):808-817
In this work, the application of an undecimated wavelet transformation together with digital interferometric contrast to improve the resulting reconstructions in a digital hard X‐ray Gabor holographic microscope is shown. Specifically, the starlet transform is used together with digital Zernike contrast. With this contrast, the results show that only a small set of scales from the hologram are, in effect, useful, and it is possible to enhance the details of the reconstruction. 相似文献
47.
James T. Brewster II Apolonio Aguilar Gonzalo Anguera Hadiqa Zafar Matthew D. Moore 《Journal of Coordination Chemistry》2018,71(11-13):1808-1813
AbstractThe reaction between amethyrin and non-aqueous uranyl silylamide (UO2[N(SiMe3)2]2) under anaerobic conditions affords a bench-stable uranyl complex. UV–vis spectroscopy, cyclic voltammetry, as well as proton NMR spectroscopic analyses provide support for the conclusion that all six pyrrole subunits participate in coordination of the uranyl dication and that, upon complexation, the amethyrin-core undergoes a 2-electron oxidation to yield a formal 22 π-electron aromatic species. 相似文献
48.
Dr. Felipe L. Coelho Eduarda S. Gil Dr. Paulo F. B. Gonçalves Dr. Leandra F. Campo Dr. Paulo H. Schneider 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(34):8157-8162
In this work, a series of 2-chalcogenylindoles was synthesized by an efficient methodology, starting from chalcogenoalkynes, including a previously unreported tellurium indole derivative. For the first time, these 2-substituted chalcogenylindoles were obtained in the absence of metal catalyst or base, under thermal conditions only. In addition, the results described herein represent a methodology with inverse regioselectivity for the chalcogen functionalization of indoles. 相似文献
49.
Guimaraes Giulia A. A. Lacerda Janiny N. Xing Yutao Ponzio Eduardo A. Pacheco Wagner F. Semaan Felipe S. Dornellas Rafael M. 《Journal of Solid State Electrochemistry》2020,24(8):1769-1779
Journal of Solid State Electrochemistry - This work presents the development and characterization of an electrochemical sensor of tin hexacyanoferrate (SnHCF), produced from the modification by... 相似文献
50.
Raúl Felipe-Sosa Raúl Felipe Juana Sánchez-Ortega Michael K. Kinyon 《Linear and Multilinear Algebra》2013,61(6):811-830
We adapt the algorithm of Kolesnikov and Pozhidaev, which converts a polynomial identity for algebras into the corresponding identities for dialgebras, to the Cayley–Dickson doubling process. We obtain a generalization of this process to the setting of dialgebras, establish some of its basic properties, and construct dialgebra analogues of the quaternions and octonions. 相似文献