Search results for "Reactivity"
showing 10 items of 880 documents
[Psychomotor disadaptation syndrome].
2014
We describe the psychomotor disadaptation syndrome and report the last findings on its physiopathology and therapeutic. This syndrome was first described by Pr Gaudet's team in 1986 and named "psychomotor regression syndrome". This name has been recently changed into "psychomotor disadaptation syndrome".The psychomotor disadaptation syndrome is a decompensation of postural function, gait and psychomotor automatisms due to the alteration of the posture and motor programming. That alteration is linked to subcortical-frontal lesions. Clinically, the psychomotor disadaptation syndrome is characterized by postural impairments (retro-propulsion or backward disequilibrium), non-specific gait disor…
Proton presence and motion in rhenium-oxide films and their application to liquid-crystalline cells
2007
Disordered solid phases, containing appreciable amounts of hydrogen ions, are grown at the surface of rhenium oxide crystals, because of the high reactivity of this compound with ambient moisture. To investigate such phenomena, a comparative study is performed on ground powder and thermally evaporated or sputtered films using x-ray diffraction and micro-Raman spectroscopy. Two types of solid phases were found in the films: HxReO3 distorted perovskite structures, based on corner-sharing ReO6 octahedra as in the bulk crystals, and ordered HReO4 crystalline structures, based on tetrahedral perrhenate ions. The complex impedance measurements on ReO3 films support the hypothesis of mobile hydrog…
Synthesis, Structure, and Reactivity of (Dihydrogen)(hydrido)iron(II) Complexes Bearing Chiral Diphosphanes
2015
The heterolytic cleavage of molecular hydrogen by [Fe(H2O)6][BF4]2 and the chiral phosphane (+)-1,2-bis[(2R,5R)-2,5-dimethylphospholano]benzene [(R,R)-Me-DuPhos] or its enantiomer [(S,S)-Me-DuPhos] yields the (dihydrogen)(hydrido)iron complexes [FeH(2-H2){(R,R)-Me-DuPhos}2]BF4 ([R,R-1]BF4) and [FeH(2-H2){(S,S)-Me-DuPhos}2]BF4 ([S,S-1]BF4), respectively. These complexes are fluxional in solution at room temperature, and the trans isomers are observed at 200 K. The ()-cis-[R,R-1]BF4 complex was identified crystallographically as the only stereoisomer at room temperature. The energetic and structural differences between the cis ( and ) and trans isomers were analyzed from a computational (DFT)…
The Chemistry of [1,2,3]Triazolo[1,5- a] pyridines
2003
The reactivity of [1,2,3]triazolo[1,5-a]pyridines 1 is described. Triazolopyridines react with electrophiles in two contrasting ways, giving 3-substituted triazolopyridines 2, or products 3, resulting from triazolo ring opening with loss of molecular nitrogen. The triazolopyridines can be lithiated at -40 degrees C by lithium diisopropylamide in ether giving regiospecifically the 7-lithio derivative. Bromotriazolopyridines have activation towards nucleophilic substitution at position 5 and 7, and benzenoid inertness at position 6. The parent compound 1a is easily hydrogenated giving tetrahydrotriazolopyridine 11a in high yield; when the triazolopyridines have substituents, the hydrogenation…
The Reactivity of 4’-Substituted Spiro[Isoindole-1,3’-pyrazoles] Derivatives: Substitution/Elimination Reactions and Access to Biaryl Derivatives
2017
This paper describes aspects of the chemistry of 4’-substituted spiro [indole-1,3’-pyrazoles]. These compounds underwent substitution and/or elimination reactions to afford some new spiro- as well as biaryl derivatives of potential pharmaceutical relevance. Mechanistic considerations are discussed as well.
Severity of dependence modulates smokers' neuronal cue reactivity and cigarette craving elicited by tobacco advertisement
2010
Smoking-related cues elicit craving and mesocorticolimbic brain activation in smokers. Severity of nicotine dependence seems to moderate cue reactivity, but the direction and mechanisms of its influence remains unclear. Although tobacco control policies demand a ban on tobacco advertising, cue reactivity studies in smokers so far have not employed tobacco advertisement as experimental stimuli. We investigated whether tobacco advertisement elicits cue reactivity at a behavioral (subjective craving) and a neural level (using functional magnetic resonance imaging) in 22 smokers and 21 never-smokers. Moreover, we studied the influence of severity of dependence on cue reactivity. In smokers, tob…
ChemInform Abstract: Chemistry and Properties of Solids with the (NZP) Skeleton
2010
Abstract Solids with an [NZP] skeleton in their structure from a very broad family presenting very different properties with varying chemical composition. These properties range from radioactive nuclide immobilization and insulation to ionic and/or electronic conduction, extending to the field of very low thermal expansion among others. The open [NZP] skeleton provides the stability and flexibility necessary to form continuous ranges of solid solution, allowing the tailoring of the best composition-property-structure material. Chemical activity may become particularly high at the surface and absorption reactions and catalytic properties have the highest interest at present. In this paper, c…
Horseradish peroxidase-catalyzed oxidation of chlorophyll a with hydrogen peroxide
2010
Horseradish peroxidase was verified to catalyze, without any phenol, the hydrogen peroxide oxidation of chlorophyll a (Chl a), solubilized with Triton X-100. The 13(2)(S) and 13(2)(R) diastereomers of 13(2)-hydroxyChl a were characterized as major oxidation products (ca. 60%) by TLC on sucrose, UV-vis, (1)H, and (13)C NMR spectra, as well as fast-atom bombardment MS. A minor amount of the 15(2)-methyl, 17(3)-phytyl ester of Mg-unstable chlorin was identified on the basis of its UV-vis spectrum and reactivity with diazomethane, which converted it to the 13(1),15(2)-dimethyl, 17(3)-phytyl ester of Mg-purpurin 7. The side products (ca. 10%) were suggested to include the 17(3)-phytyl ester of M…
Phosphorylated micro- vs. nano-cellulose: a comparative study on their surface functionalisation, growth of titanium-oxo-phosphate clusters and remov…
2019
Controlled cellulose disassembly affords many variants including amorphous micro-sized cellulose crystals (MCC) and cellulose nano-sized crystals (CNC), which have emerged recently as green and sustainable nanomaterials. Unfortunately, their lower reactivity and thermal and chemical instability constitute an impediment for multifaceted nanoscience and nanotechnology usage. Herein, MCC and CNC are functionalised using two phosphorus derivatives (phosphoryl chloride and hexachlorocyclotriphosphazene), under acid-free, urea-free and corrosive-free, gentle experimental conditions. Notably, CNC can accommodate more phosphorus species compared to MCC, with the bulky phosphazene precursor being le…
O2(a1Δg) + Mg, Fe, and Ca: experimental kinetics and formulation of a weak collision, multiwell master equation with spin-hopping
2012
The first excited electronic state of molecular oxygen, O(2)(a(1)Δ(g)), is formed in the upper atmosphere by the photolysis of O(3). Its lifetime is over 70 min above 75 km, so that during the day its concentration is about 30 times greater than that of O(3). In order to explore its potential reactivity with atmospheric constituents produced by meteoric ablation, the reactions of Mg, Fe, and Ca with O(2)(a) were studied in a fast flow tube, where the metal atoms were produced either by thermal evaporation (Ca and Mg) or by pulsed laser ablation of a metal target (Fe), and detected by laser induced fluorescence spectroscopy. O(2)(a) was produced by bubbling a flow of Cl(2) through chilled al…