Search results for "note"
showing 10 items of 10709 documents
Non-covalent graphene nanobuds from mono- and tripodal binding motifs.
2017
Graphene nanobuds were prepared via the non-covalent anchoring of C60-based molecules endowed with one or three pyrene units, respectively. TGA, FTIR, UV-Vis and TEM investigations confirmed the formation of nanohybrids. For the two molecular derivatives, striking differences were determined in their interaction with graphene or carbon surfaces by Raman, cyclic voltammetry and molecular mechanics calculations, revealing the important role of pyrene adsorption in modulating the electronic properties of the nanohybrids.
Temperature-Induced Structural Transitions in the Gallium-Based MIL-53 Metal–Organic Framework
2013
We report a structural and thermodynamic investigation of the phase behavior of Ga(OH,F)-MIL-53, a gallium-based metal–organic framework (MOF) having the MIL-53 topology containing 0.7 wt % fluorine bonded to the metal. Despite some small structural differences, especially for the hydrated form, the overall physical chemistry behavior of Ga(OH,F)-MIL-53 is very similar to standard fluorine free Ga-MIL-53 material. A combination of in situ X-ray diffraction, in situ Fourier transform infrared spectroscopy, differential scanning calorimetry, and heat capacity measurements allowed us to establish that Ga(OH,F)-MIL-53 under vacuum (i.e., the empty material) exhibits two stable phases: a nonporo…
l-Arabinose Conformers Adsorption on Ruthenium Surfaces: A DFT Study
2012
Adsorption of 5 L-arabinose tautomers – one acyclic and four cyclic (α and β, pyranose and furanose) species – on a ruthenium surface was studied as a precursor-process of the, nowadays more and more, industrially important sugar catalytic hydrogenation on metal surfaces in water medium. The study was mostly referred to a 37-atom metal catalyst fragment, even though border-effects on the adsorption processes were also checked employing a 61-atom metal fragment. In order to figure out conformational effects on the title process the tautomer flexibility was, at first, investigated by the genetic-algorithm based code Balloon, considering the conformational spaces of the different aquo tautomer…
Electrochemical and bioelectrocatalytical properties of novel block-copolymers containing interacting ferrocenyl units
2008
The electrochemical characterization of three different polystyrene-b-polybutadiene block-copolymers, functionalized with diferrocenylsilane units, is reported. The PB-blocks have been functionalized with different fractions of electronicall y communicated, PSm-PB„ p (HSiMeFc2)p units, where m = 615, n = 53, p = 39 (1), m = 375, n = 92, p = 76 (2) and m = 455, n = 204, p = 170 (3). Electrochemical character ization has been carried out both in solution and after electrochemical deposition onto platinum electrodes. The bioelectrocatalytical properties of electrodes modified with the polymers in the nicotinamide dinucleotide (NADH) and glucose oxidase (GOx) oxidations have been investigated …
Photochemistry of the H2O/CO System Revisited : The HXeOH···CO Complex in a Xenon Matrix
2017
We report on the complex of a noble-gas hydride HXeOH with carbon monoxide. This species is prepared via the annealing-induced H + Xe + OH···CO reaction in a xenon matrix, the OH···CO complexes being produced by VUV photolysis of the H2O···CO complexes. The H–Xe stretching mode of the HXeOH···CO complex absorbs at 1590.3 cm–1 and it is blue-shifted by 12.7 cm–1 from the H–Xe stretching band of HXeOH monomer. The observed blue shift indicates the stabilization of the H–Xe bond upon complexation, which is characteristic of complexes of noble-gas hydrides. The HXeOH···CO species is the first complex of a noble-gas hydride with carbon monoxide and the second observed complex of HXeOH. On the ba…
Selective Cobalt over Nickel separation using neat and confined ionic liquids
2020
International audience; Task Specific Ionic Liquids (TSILs) generated by association between tetraalkylammonium cations and coordinating anions such as dicyanamide (Dca-) and thiocyanate (SCN-) were used for the selective separation of Ni(II) over Co(II). SCN-based TSIL presents higher extraction efficiency than the Dca-based one towards Co(II) (E = 85.4 % vs 54.6 %) and Ni (II) (E = 22 % vs 0.5%) but lower separation factors (βCo/Ni = 21 vs 239). Interestingly, extraction of Co(II) and Ni(II) in Dca-based TSIL can be enhanced using salts with chaotropic anions such as NaNO3 (E > 90 % for Co(II) and E = 85% for Ni(II)). The use of NaCl allows, moreover, the efficient separation of both ions…
Comparative analysis of the remineralization potential of CPP–ACP with Fluoride, Tri-Calcium Phosphate and Nano Hydroxyapatite using SEM/EDX – An in …
2019
Background In recent years, the non-invasive management of non cavitated caries lesions using remineralization systems to repair the enamel have received more attention from the scientific community. Aim: To quantitatively evaluate the remineralization potential of Casein phosphopeptide-amorphous calcium phosphate-fluoride(CPP-ACPF), Tri-calcium phosphate(TCP) & Nano-hydroxyapatite(nHAP) using Scanning Electron Microscopy(SEM) and Energy dispersive X-ray Analysis(EDX). Material and Methods 40 enamel specimens were prepared, and immersed in demineralising solution at a pH of 4.4 for 96 hours at 37°C, to induce artificial carious lesions. Remineralization was carried out for a period of 30 da…
Selective Gold Recovery and Catalysis in a Highly Flexible Methionine-Decorated Metal–Organic Framework
2016
A novel chiral 3D bioMOF exhibiting functional channels with thio-alkyl chains derived from the natural amino acid l-methionine (1) has been rationally prepared. The well-known strong affinity of gold for sulfur derivatives, together with the extremely high flexibility of the thioether "arms" decorating the channels, account for a selective capture of gold(III) and gold(I) salts in the presence of other metal cations typically found in electronic wastes. The X-ray single-crystal structures of the different gold adsorbates Au(III)@1 and Au(I)@1 suggest that the selective metal capture occurs in a metal ion recognition process somehow mimicking what happens in biological systems and protein r…
The influence of Fe3+ doping on thermally induced crystallization and phase evolution of amorphous calcium phosphate
2021
The present study investigates thermally induced crystallization and phase evolution of amorphous calcium phosphate (ACP) partially substituted with Fe3+ ions (M/P = 1.5 : 1). It was demonstrated that the presence of Fe3+ ions radically changes the crystallization behavior of ACP and completely prevents the formation of α-tricalcium phosphate (α-TCP, Ca3(PO4)2), which is the first crystalline phase obtained from non-substituted ACP upon thermal treatment. Surprisingly, calcium deficient hydroxyapatite (CDHA) was obtained instead of α-TCP. Such unusual crystallization behavior was observed with a doping level as low as 0.1 mol% with respect to Ca ions. Moreover, it was shown that the presenc…
Electrochemical Characterization of Corrosion Products in Leaded Bronze Sculptures Considering Ohmic Drop Effects on Tafel Analysis
2015
[EN] The characterization of corrosion products in leaded bronze based on the voltammetry of immobilized particles methodology is described. Voltammetric data, supported by Fourier transform infra-red spectroscopy, field emission scanning electron microscopy-energy dispersive X-ray microanalysis (FESEM-EDX) and scanning electrochemical microscopy (SECM) allow the identification of copper and lead corrosion materials. The mutual influence of such products is modeled upon considering uncompensated ohmic drops in the Tafel analysis of the rising portion of the respective voltammetric signals for their electrochemical reduction.