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排序方式: 共有201条查询结果,搜索用时 242 毫秒
31.
Alexandra Belcovici Carmen Ioana Fort Laura Elena Mureşan Ioana Perhaiţa Gheorge Borodi Graziella Liana Turdean 《Electroanalysis》2023,35(5):e202200395
ZnO nanoparticles (ZnO-NP) were prepared by a facile precipitation technique using di-isopropyl amine as precipitating agent. The morpho-structure and porosity of the as-prepared nano-powder were investigated by FT-IR analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), and BET analysis. By drop-casting, a composite film was deposited to obtain ZnO-NP-Nafion/GCE modified electrode. The modified electrode was investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and square wave anodic stripping voltammetry (SWASV) for the detection of Pb2+, Cd2+, Cu2+, and Fe3+, and it was successfully applied for the detection of Pb2+ and Cu2+ in real water samples. 相似文献
32.
This paper reports on the use of electrochemical surface plasmon resonance (E-SPR) for the detection of carbohydrate-binding proteins. The generation of an SPR sensor specific to lectins Arachis hypogaea (PNA) and Maackia amurensis (MAA) is based on the electrochemical polymerization of oligosaccharide derivatives functionalized by pyrrole groups. The resulting thin conducting polymer films were characterized using E-SPR and atomic force microscopy (AFM). The specific binding of PNA to polypyrrole-lactosyl and of MAA to polypyrrole-3'-sialyllactosyl films was investigated using SPR. The detection limit was 41 nM for PNA and 83 nM for MAA. Through Scatchard analysis and linear transformation of the SPR sensorgram data, association (k(ass)) and dissociation rate constants (k(diss)) could be determined. 相似文献
33.
D. Mazzotti P. De Natale G. Giusfredi C. Fort J.A. Mitchell L.W. Hollberg 《Applied physics. B, Lasers and optics》2000,70(6):747-750
We report difference-frequency generation (DFG) in periodically poled lithium niobate (PPLN) around 4.25 μm using a cw Nd:YAG
and an injection-locked diode laser. This system provides a narrow linewidth source at 4.25 μm with near-shot-noise-limited
operation. A conversion efficiency close to the theoretical limit is obtained. Detection of CO2 absorption spectra is demonstrated and further improvements and applications to high sensitivity spectroscopy are discussed.
Received: 12 August 1999 / Revised version: 21 January 2000 / Published online: 24 March 2000 相似文献
34.
The synthesis and screening of two beta-D-Galp-(1-3)-beta-d-GlcpN (lacto-N-biose) disaccharide libraries are reported. Solution-phase synthetic modifications at the HO-2' and NH positions were performed in an effort to enhance the affinity toward galectin-3, a galactose-binding protein involved in tumor metastasis, apoptosis, and inflammation. The libraries were screened for galectin-3 binding by microscale frontal affinity chromatography coupled to mass spectrometry (FAC/MS) allowing for rapid ranking of the different inhibitors and the determination of the galectin-3 binding Kd's. Compounds bearing a hydrophobic substituent on the NH group showed the highest affinity for the lectin. The N-naphthoyl derivative (Kd = 10.6 microM) was the best inhibitor with a 7 times increased affinity as compared to the N-acetyl parent compound (Kd = 73.3 microM). 相似文献
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37.
T. Solouki R. C. Fort A. Alomary A. Fattahi 《Journal of the American Society for Mass Spectrometry》2001,12(12):1409-1285
We utilized gas phase hydrogen/deuterium (H/D) exchange reactions and ab initio calculations to investigate the complexation between a model peptide (Arg-Gly-AspRGD) with various alkali metal ions. The peptide conformation is drastically altered upon alkali metal ion complexation. The associated conformational changes depend on both the number and type of complexing alkali metal ions. Sodium has a smaller ionic diameter and prefers a multidentate interaction that involves all three amino acids of the peptide. Conversely, potassium and cesium form different types of complexes with the RGD. The [RGD + 2Cs − H]+ species exhibit the slowest H/D exchange reactivity (reaction rate constant of 6 × 10−13 cm3molecule−1s−1 for the fastest exchanging labile hydrogen with ND3). The reaction rate constant of the protonated RGD is two orders of magnitude faster than that of the [RGD + 2Cs − H]+. Addition of the first cesium to the RGD reduces the H/D exchange reaction rate constant (i.e., D0) by a factor of seven whereas sodium reduces this value by a factor of thirty. Conversely, addition of the second alkali metal ions has the opposite effect; the rate of D0 disappearance for all [RGD + 2Met − H]+ species (MetNa, K, and Cs) decreases with the alkali metal ion size. 相似文献
38.
Alexis Gosset Dr. Štěpánka Nováková Lachmanová Dr. Sawsen Cherraben Dr. Gildas Bertho Jérémy Forté Dr. Christian Perruchot Dr. Henri-Pierre Jacquot de Rouville Dr. Lubomír Pospíšil Dr. Magdaléna Hromadová Dr. Éric Brémond Dr. Philippe P. Lainé 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(71):17889-17899
The synergistic functioning of redox-active components that emerges from prototypical 2,2′-di(N-methylpyrid-4-ylium)-1,1′-biphenyl is described. Interestingly, even if a trans conformation of the native assembly is expected, due to electrostatic repulsion between cationic pyridinium units, we demonstrate that cis conformation is equally energy-stabilized on account of a peculiar LUMO (SupLUMO) that develops through space, encompassing the two pyridiniums in a single, made-in-one-piece, electronic entity (superelectrophoric behavior). This SupLUMO emergence, with the cis species as superelectrophore embodiment, originates in a sudden change of electronic structure. This finding is substantiated by insights from solid state (single-crystal X-ray diffraction) and solution (NOE NMR and UV-vis-NIR spectroelectrochemistry) studies, combined with electronic structure computations. Electrochemistry shows that electron transfers are so strongly correlated that two-electron reduction manifests itself as a single-step process with a large potential inversion consistent with inner creation of a carbon-carbon bond (digital simulation). Besides, absence of reductive formation of dimers is a further indication of a preferential intramolecular reactivity determined by the SupLUMO interaction (cis isomer pre-organization). The redox-gated covalent bond, serving as electron reservoir, was studied via atropisomerism of the reduction product (VT NMR study). The overall picture derived from this in-depth study of 2,2′-di(N-methylpyrid-4-ylium)-1,1′-biphenyl proves that trans and cis species are worth considered as intrinsically sharply different, that is, as doubly-electrophoric and singly-superelectrophoric switchable assemblies, beyond conformational isomerism. Most importantly, the through-space-mediated SupLUMO may come in complement of other weak interactions encountered in Supramolecular Chemistry as a tool for the design of electroactive architectures. 相似文献
39.
In methanol, 2-alkyl-3-aryl-2-cyclohexenones undergo an oxidative photocyclization at 254 nm to provide polycyclic compounds with a phenanthrenic skeleton. 相似文献
40.