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111.
Furans are an important class of compounds and exhibit a diverse range of activities and properties. As such, improved synthetic access to furans is an important research goal. In the present report, a solvent- and catalyst-free reaction between 5,5-dimethyl-1,3-cyclohexanedione (dimedone), an aryl aldehyde and an isocyanide under microwave irradiation is presented. This method is significantly improved from previously described protocols in terms of applicability of wide ranging aryl aldehydes, better yields, shorter reaction times, facile work up and essentially no need of column chromatography. The photophysical properties of this series of compounds were studied for their possible applicability in the field of metal ion sensors. In solution, two compounds, 2-(cyclohexylamino)-3-(1H-indol-3-yl)-6,6-dimethyl-6,7-dihydrobenzofuran-4(5H)-one (1 i) and 2-(tert-butylamino)-3-(1H-indol-3-yl)-6,6-dimethyl-6,7-dihydrobenzofuran-4(5H)-one (1 j), underwent an observable color change from yellow to colorless in the presence of aluminum(III) ions. Further studies to investigate the UV absorption and luminescence behavior of these compounds revealed their utility as “naked-eye sensors” for aluminum detection. 相似文献
112.
Jeffrey T. La Belle Miti Shah Justin Reed Vivek Nandakumar T. L. Alford James W. Wilson Cheryl A. Nickerson Lokesh Joshi 《Electroanalysis》2009,21(20):2267-2271
An immunosensor for rapid and low level detection of the bacterial pathogen Salmonella enterica Serovar Typhimurium was designed and developed based upon label‐free electrochemical impedance spectroscopy and correlated to viable cell counts. The immunosensor was fabricated by electroplating gold onto a disposable printed circuit board (PCB) electrode by immobilizing monoclonal antibody (MAb) specific against Salmonella typhimurium cell surface lipopolysaccharide (LPS) onto the surface of the electrode. Use of mass‐fabricated and electroplated PCB electrodes allowed for disposable, highly sensitive, and rapid detection of Salmonella in an aqueous environment. Results demonstrate that in purified solution, Salmonella can be detected as low as 10 CFU in a 100 μL volume and label‐free and rapid manner in fewer than 90 s. The cost effective approach described here can be used for detection of pathogens with relevance for healthcare, food, and environmental applications. 相似文献
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Adefunke O. Koyejo Dr. Lokesh Kesavan Dr. Pia Damlin Dr. Mikko Salomäki Jenevieve G. Yao Prof. Minna Hakkarainen Prof. Carita Kvarnström 《ChemElectroChem》2020,7(24):4889-4899
Cellulose-based reduced graphene oxide materials (r-nGO) were fabricated and anchored onto polyvinyl alcohol stabilized gold nanoparticles. Their potential in applications in the electrocatalytic reduction of CO2 (ER-CO2) is demonstrated. The nGO was synthesized by microwave-assisted cellulose carbonization followed by two different reduction methods, that is, with super-heated water (i) or caffeic acid (ii). These materials, denoted as r-nGO (i) r-nGO-CA (ii), were utilized to immobilize colloidal gold nanoparticles (Au NPs) in an aqueous environment. The two r-nGO-supported Au NP materials were deposited on glassy carbon electrode surfaces and studied as catalysts for ER-CO2. ER-CO2 was investigated at room temperature and pressure (RTP) using ionic liquids (RTILs) or an aprotic solvent acetonitrile (ACN). Tetrabutylammonium hexafluoroborate (TBAPF6) was used as an electrolyte salt in the case of ACN. The current response resulting from ER-CO2 was measured under cyclic voltammetric conditions using a one-compartment three-electrode cell. Results showed that, r-nGO-supported gold nanoparticles catalyze ER-CO2 and they significantly reduce the overpotential of CO2 reduction from −1.9 V to −1.6 V vs. Ag/AgCl. Moreover, of all the materials studied, Au/r-nGO was superior in reducing CO2 in both RTILs and TBAPF6/ACN. These outcomes serve as grounds for the further development of electrocatalysts from bio-based reduced graphene oxides. 相似文献
114.
Florian Hastreiter Corinna Lorenz Johnny Hioe Stefanie Grtner Nanjundappa Lokesh Nikolaus Korber Ruth M. Gschwind 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(10):3165-3169
The existence of [μ‐HSi4]3? in liquid ammonia solutions is confirmed by 1H and 29Si NMR experiments. Both NMR and quantum chemical calculations reveal that the H atom bridges two Si atoms of the [Si4]4? cluster, contrary to the expectation that it is located at one vertex Si of the tetrahedron. The calculations also indicate that in the formation of [μ‐HSi4]3?, protonation is driven by a high charge density and an increase of electron delocalization compared to [Si4]4?. Additionally, [Si5]2? was detected for the first time and characterized by NMR. Calculations show that it is resistant to protonation, owing to a strong charge delocalization, which is significantly reduced upon protonation. Thus, our methods reveal three silicides in liquid ammonia: unprotonated [Si5]2?, terminally protonated [HSi9]3?, and bridge‐protonated [μ‐HSi4]3?. The protonation trend can be roughly predicted by the difference in charge delocalization between the parent compound and the product, which can be finely tuned by the presence of counter ions in solution. 相似文献
115.
We develop a method to seamlessly simulate flows over a wide range of Knudsen numbers past arbitrarily shaped immersed boundaries. To achieve seamless computation, ie, not use any zone division to distinguish between continuum and non‐continuum regions, we use the unified gas kinetic scheme (UGKS), which is based on the Bhatnagar‐Groos‐Krook (BGK) approximation of the Boltzmann equation. We combine UGKS with an appropriately designed Cartesian grid method (CGM) to allow us to compute flows past arbitrary boundaries. The CGM we use here satisfies boundary conditions at the wall by using a constrained least square interpolation procedure. However, it differs from the usual, continuum CGMs in 2 ways. Firstly, to allow us capture non‐continuum effects at the boundaries, the CGM used herein interpolates the microscopic velocity distribution function in addition to the macroscopic variables. Secondly, even for the macroscopic variables, we use a gas kinetic method–based density interpolation procedure at the boundaries that allows the CGM to interface well with the UGKS method. We demonstrate the robustness and efficacy of the method by testing it on stationary immersed boundaries at various Knudsen numbers ranging from continuum to transition regimes. 相似文献
116.