Search results for "nanotechnology"
showing 10 items of 9818 documents
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.
Towards oxalate-bridged iron(ii), cobalt(ii), nickel(ii) and zinc(ii) complexes through oxotris(oxalato)niobate(v): an open air non-oxidizing synthet…
2018
Four compounds with the formula [M2(dmphen)4(μ-C2O4)](ClO4)2·2dmso [M = Fe (1), Co (2) and Zn (4); dmphen = 2,9-dimethyl-1,10-phenanthroline] and [Ni2(dmphen)4(μ-C2O4)]3[NbO(C2O4)3]2·16H2O (3) have been synthesized using the tris(oxalato)oxoniobate(V) complex anion as the oxalate source, and their structures have been determined by single crystal X-ray diffraction. X-ray quality crystals of highly insoluble oxalate-bridged species were obtained by taking advantage of the slow release of oxalate by the tris(oxalato)oxoniobate(V) complex anion. The structures of 1–4 all contain oxalate-bridged dimetal(II) units with didentate dmphen molecules acting as end-cap ligands; electroneutrality is ac…
Maturation of a Key Resource – The Germanium-68/Gallium-68 Generator: Development and New Insights
2011
(68)Ge/(68)Ga radionuclide generators have been investigated for almost fifty years, since the cyclotron-independent availability of positron emitting (68)Ga via the (68)Ge/(68)Ga system had always attracted researches working in basic nuclear chemistry as well as radiopharmaceutical chemistry. However, it took decades and generations of research (and researchers) to finally reach a level of (68)Ge/(68)Ga radionuclide generator designs adequate to the modern requirements of radiometal labelling chemistry. Nevertheless, most of the existing commercial generator systems address aspects of (68)Ge breakthrough and safe synthesis of (68)Ga radiopharmaceuticals by adopting eluate post-processing …
Atrane complexes chemistry as a tool for obtaining trimodal UVM-7-like porous silica
2018
[EN] The use of atrane complexes as hydrolytic precursors enables the homogeneous incorporation of manganese (25Si/Mn48) throughout the porous walls of the nanoparticles of a surfactant-templated bimodal mesoporous silica (UVM-7). The subsequent leaching of the manganese nanodomains allows adding controlled microporosity to the host silica framework. The resulting final silica material presents three pore systems structured at different length scales: interparticle textural-type macroporosity (ca. 43.2nm), ordered intraparticle mesoporosity (ca. 2.63nm; after template removal), and well-dispersed microporosity (< 2nm; as consequence of the lixiviation of the Mn-rich domains). The good dispe…