Search results for "bond."
showing 10 items of 3516 documents
Pickering Emulsion Gels Based on Halloysite Nanotubes and Ionic Biopolymers: Properties and Cleaning Action on Marble Surface
2019
We have fabricated ecocompatible Pickering emulsions based on halloysite nanotubes and ionic biopolymers (chitosan and pectin) from renewable resources. The effect of pectin and chitosan on the Pickering emulsion was investigated by direct visualization of the oil droplets and by the thermodynamic characterization at the interface. Pectin enhances the Pickering emulsion stability, while a phase separation and nonhomogeneous gel was observed in the presence of chitosan. We have demonstrated that the Pickering emulsion in a pectin based gel phase is suitable for wax layer removal from a marble surface. A controlled cleaning is achieved by tuning the contact time between the gel and the marble…
La persistance de la performance des fonds de pension individuels britanniques : une étude empirique sur des fonds investis en actions et des fonds o…
2003
Dans ce présent cahier de recherche, nous nous proposons d’étudier la stabilité des performances de certains fonds de retraite anglais à cotisations définies : les fonds de pension individuels (Personal Pension Scheme). Il s’agit de fonds – pratiquant une gestion active - investissant principalement dans les actions britanniques et de fonds détenant majoritairement des obligations anglaises durant la période novembre 1990 – novembre 2000. Les données sur les fonds de pension individuels proviennent de la base de données UK PENSION de Standard & Poor’s Fund Services et sont de fréquence mensuelle. Nous utilisons des tests paramétriques de l’existence de la persistance, plusieurs mesures de p…
Structural and electronic elucidation of a N-heterocyclic silylene vanadocene adduct
2017
The solid and solution state structure of the vanadium(II) N‐ heterocyclic silylene (NHSi) complex, [(SiIPr)V(Cp)2] (1) is reported ( SiIPr: 1,3‐bis(2,6‐diisopropylphenyl)‐1,3‐diaza‐2‐silacyclopent‐4‐ en‐2‐ylidene). The electronic structure of 1 is probed using combination of magnetic measurements, EPR spectroscopy and computational studies. The V–Si bond strength and complex forming mechanism between vanadocene and NHSi ligand is elucidated using computational methods. peerReviewed
Shear and flexural strength of corroded R.C. beams
2016
Simplified equations aimed at evaluating the flexural and shear capacity of corroded R.C. beams are presented and discussed in this paper, with reference to ordinary beams reinforced both longitudinally (with same-size bars) and transversely (with stirrups). A model is developed to take care of diffused and localised corrosion (pitting corrosion), concrete decay in compression and bond-strength decay at concrete-reinforcement interface. A fairly innovative contribution of this study is the introduction into the proposed equations of the main parameters governing the corrosion processes. The proposed approach is simple and effective, and may be adopted in the assessment of many damaged struc…
PtII versus PdII-assisted [2+3] cycloadditions of nitriles and nitrone. Synthesis of nitrile-derived arylamido platinum(II) and Δ4-1,2,4-oxadiazoline…
2019
Abstract The reactions of bis(organonitrile) platinum(II) complexes trans-[PtCl2(N CR)2] (R = C6H4(p-HC O), CH2C6H4(p-CH3)) with pyrroline N-oxide −O+N CHCH2CH2CMe2 afford arylamido platinum(II) complexes trans-[PtCl2{(O CR)N CCH2CH2CMe2NH}2] (R = C6H4(p-HC O) (1), CH2C6H4(p-CH3) (2)). The spectral data of 1 and 2 show that the oxadiazoline rings in both cases have opened by a spontaneous N O bond cleavage to form (Z)-p-formyl-N-(5,5-dimethylpyrrolidin-2-ylidene)benzamide or (Z)-N-(5,5-dimethylpyrrolidin-2-ylidene)-2-p-tolylacetamide ligands, respectively, where the N-atoms of the benzamide or acetamide moieties coordinate to platinum(II) metal centre in trans positions. However, the reacti…
Bis(hydroxyammonium) hexachloridoplatinate(IV)–18-crown-6 (1/2)
2014
In the title complex, (NH3OH)2[PtCl6]·2C12H24O6, the PtIV atom is coordinated by six chloride anions in a slightly distorted octahedral geometry. The Pt—Cl bond lengths are comparable to those reported for other hexachloridoplatinate(IV) species. The hydroxyammonium groups act as linkers between the [PtCl6]2− anion and the crown ether molecules. The anion is linked to two hydroxyammonium cations via O—H...Cl hydrogen bonds and each hydroxyammonium moiety is linked to a crown ether molecule by hydrogen bonds between ammonium H atoms and 18-crown-6 O atoms. The crown ether molecules have the classic crown shape in which all O atoms are located in the inner part of the crown ether ring and all…
Supramolecular Assembly of Metal Complexes by (Aryl)I⋯dz2[PtII] Halogen Bond
2020
The theoretical data for the half‐lantern complexes [Pt(C^N)(μ‐S^N)] 2 ( 1 – 3 ; С^N is cyclometalated 2‐Ph‐benzothiazole; S^N is 2‐SH‐pyridine 1 , 2‐SH‐benzoxazole 2 , 2‐SH‐tetrafluorobenzothiazole 3 ) indicate that the Pt···Pt orbital interaction leads to an increment of the nucleophilicity of the outer d z 2 ‐orbitals to provide assembly with electrophilic species. 1 – 3 were co‐crystallized with bifunctional halogen bond (XB) donors to give adducts ( 1 – 3 ) 2 ∙(1,4‐diiodotetrafluorobenzene) and infinite polymeric [ 1 ·1,1’‐diiodoperfluorodiphenyl] n . X‐ray crystallography revealed that the supramolecular assembly is achieved via (Aryl)I∙∙∙ d z 2 [Pt II ] XB between iodine σ‐holes and …
Noncovalent axial I∙∙∙Pt∙∙∙I interactions in platinum(II) complexes strengthen in the excited state
2021
Abstract Coordination compounds of platinum(II) participate in various noncovalent axial interactions involving metal center. Weakly bound axial ligands can be electrophilic or nucleophilic; however, interactions with nucleophiles are compromised by electron density clashing. Consequently, simultaneous axial interaction of platinum(II) with two nucleophilic ligands is almost unprecedented. Herein, we report structural and computational study of a platinum(II) complex possessing such intramolecular noncovalent I⋅⋅⋅Pt⋅⋅⋅I interactions. Structural analysis indicates that the two iodine atoms approach the platinum(II) center in a “side‐on” fashion and act as nucleophilic ligands. According to c…
Apparent and quantitative loss of fatty acids and triacylglycerols at frying temperatures
2012
[EN]: Olive and sunflower oils were heated at 180 °C for 5, 10 and 15 hours with the aim of defining the changes in the contents of fatty acid methyl esters (FAME) and triacylglycerols (TAG) under frying conditions. Differences between apparent and real loss of FAME or TAG are defined for an adequate interpretation of the changes taking place at high temperature. Such differences depend on the expression of the results and frequently result in erroneous conclusions. Results showed that from the normalized composition it could be deduced that only the most unsaturated FAME (C18:2) or TAG containing it was significantly altered. However, quantitative data indicated that all the unsaturated FA…
Effects of Polyacrylic Acid Pre-Treatment on Bonded-Dentine Interfaces Created with a Modern Bioactive Resin-Modified Glass Ionomer Cement and Subjec…
2018
Objectives: Resin-modified glass ionomer cements (RMGIC) are considered excellent restorative materials with unique therapeutic and anti-cariogenic activity. However, concerns exist regarding the use of polyacrylic acid as a dentine conditioner as it may influence the bonding performance of RMGIC. The aim of this study was to evaluate the effect of different protocols for cycling mechanical stress on the bond durability and interfacial ultramorphology of a modern RMGIC applied to dentine pre-treated with/without polyacrylic acid conditioner (PAA). Methods: The RMGIC was applied onto human dentine specimens prepared with silicon-carbide (SiC) abrasive paper with or without the use of a PAA c…