Search results for "Reaction"
showing 10 items of 6134 documents
Surface and bulk changes of a Pt 1%/Ce0.6Zr0.4O2 catalyst during CO oxidation in the absence of O2
2004
The reduction of a Pt 1%/Ce0.6Zr0.4O2 catalyst by CO in the absence of gaseous oxygen was studied by transient reactivity tests, temperature programmed surface reaction with CO, flow thermogravimetric tests and DRIFTS experiments, in order to obtain information generally on the OSC properties and, specifically, on the mechanism of CO oxidation over both, Pt catalyst and support-only sample (Ce0.6Zr0.4O2). The results of thermogravimetric experiments showed the presence of an induction time in the weight change % of the catalyst, depending on the CO concentration in the gas flow. This induction time could be related to the presence of two oxygen reactive sites. The first one leads to strongl…
Straightforward preparation of highly loaded MWCNT-polyamine hybrids and their application in catalysis
2020
Multiwalled carbon nanotubes (MWCNTs) were easily and efficiently functionalised with highly cross-linked polyamines. The radical polymerisation of two bis-vinylimidazolium salts in the presence of pristine MWCNTs and azobisisobutyronitrile (AIBN) as a radical initiator led to the formation of materials with a high functionalisation degree. The subsequent treatment with sodium borohydride gave rise to the reduction of imidazolium moieties with the concomitant formation of secondary and tertiary amino groups. The obtained materials were characterised by thermogravimetric analysis (TGA), elemental analysis, solid state 13C-NMR, Fourier-transform infrared spectroscopy (FT-IR), transmission ele…
Analysis of the oxidation process and mechanical evolution in nanosized copper spinel ferrites. Role of stresses on the coercivity
1997
Isothermal oxidations of the iron(II) and copper(I) cations in nanosized copper spinel ferrites which were oxidized in cation-deficient spinels have been studied by thermogravimetric analysis. The low temperature kinetics of oxidation of each oxidizable cation has been explained on the basis of a diffusion-induced stress effect, these stresses being generated in the ferrite particles by the chemical gradient induced during the oxidation process where the cations at the surface are more oxidized than those in the bulk. A reaction mechanism coupling the chemical and the mechanical effects has been proposed. When the Cu-ferrites contain some Co-cations, it has also been revealed that the stres…
Palladium supported on Halloysite-triazolium salts as catalyst for ligand free Suzuki cross-coupling in water under microwave irradiation
2015
Abstract Environmental friendly halloysite-dicationic triazolium salts (second generation) obtained by subsequent click reactions of a diyne derivative in the presence of 2-azidopropyl-modified halloysite nanotubes, were used as supports for palladium catalyst. Thanks to the high triazolium loading (25%) these materials were able to support higher amount of the metal than that on the monocationic derivative (first generation). Such materials were characterized by thermogravimetric analysis, FT-IR spectroscopy and SEM investigations. The new catalytic system was employed in the ligand free Suzuki cross-coupling under microwave irradiation. A set of solvent, time and% loading of palladium was…
The anion impact on the self-assembly of naphthalene diimide diimidazolium salts
2017
Naphthalene diimide diimidazolium salts differing in the anion nature were synthesized and their properties as well as their self-assembly behaviour were investigated. In particular, we took into consideration the N,N′-bis-(1-octyl-3-propylimidazolium)-naphthalene diimide cations and anions differing in size, shape and coordination abilities like [I−], [BF4−] and [NTf2−]. After determination of thermal behaviour, using differential scanning calorimetry and thermal gravimetric analysis, the electrochemical stability and redox properties were assessed using cyclic voltammetry. The self-assembly behaviour of the salts was investigated using concentration and temperature-dependent spectroscopic…
Effect of some additives on the reactions in fly ASH-Ca(OH)2system
2004
Differential thermal analysis and thermogravimetry were used to evaluate the effect of some additives, such as CaSO4, CaCl2 and silica fume amorphous silica from ferrosilicon synthesis on the mechanism and kinetics of reactions occurring in fly ash-Ca(OH)2 system. The accelerating role of these additives was demonstrated from the data relating to Ca(OH)2 consumption in hydrated pastes, determined by TG measurements.
The catalytic reduction of nitrobenzene at the [MoVIO2(O2CC(S)(C6H5)2)2]2? complex intercalated in a Zn(II)-Al(III) layered double hydroxide host: A …
2001
The heterogeneous reduction of nitrobenzene by thiophenol catalyzed by the dianionic bis(2-sulfanyl-2,2-diphenylethanoxycarbonyl) dioxomolybdate(VI) complex, [MoVIO2(O2CC(S)(C6H5)2)2]2−, intercalated into a Zn(II)–Al(III) layered double hydroxide host [Zn3−xAlx(OH)6]x+, has been investigated under anaerobic conditions. Aniline was found to be the only product formed through a reaction consuming six moles of thiophenol for each mol of aniline produced. The kinetics of the system have been analyzed in detail. In excess of thiophenol, all reactions follow first-order kinetics (ln([PhNO2]/[PhNO2]0) = −kappt) with the apparent rate constant kapp being a complex function of both initial nitrobenz…
Thiosulfate Reduction in Salmonella enterica Is Driven by the Proton Motive Force
2012
ABSTRACT Thiosulfate respiration in Salmonella enterica serovar Typhimurium is catalyzed by the membrane-bound enzyme thiosulfate reductase. Experiments with quinone biosynthesis mutants show that menaquinol is the sole electron donor to thiosulfate reductase. However, the reduction of thiosulfate by menaquinol is highly endergonic under standard conditions (Δ E °′ = −328 mV). Thiosulfate reductase activity was found to depend on the proton motive force (PMF) across the cytoplasmic membrane. A structural model for thiosulfate reductase suggests that the PMF drives endergonic electron flow within the enzyme by a reverse loop mechanism. Thiosulfate reductase was able to catalyze the combined …
A Multi-Component Reaction towards the Development of Highly Modular Hydrogelators
2018
Herein we report a multi‐component reaction approach for the development of a new class of hydrogelators based on the OxoTriphenylHexanOate (OTHO) backbone. A focused library of OTHOs has been synthesized and their hydrogelation features evaluated. The two most potent hydrogelators were studied by rheology revealing different stiffness, appearances and thixotropic behavior of the gels. The new gelators showcase the versatility of the OTHO backbone as a platform for the design of functionalized hydrogels with tunable gel properties. peerReviewed
A G468-T AMPD1 mutant allele contributes to the high incidence of myoadenylate deaminase deficiency in the Caucasian population.
2002
Myoadenylate deaminase deficiency is the most common metabolic disorder of skeletal muscle in the Caucasian population, affecting approximately 2% of all individuals. Although most deficient subjects are asymptomatic, some suffer from exercise-induced myalgia suggesting a causal relationship between a lack of enzyme activity and muscle function. In addition, carriers of this derangement in purine nucleotide catabolism may have an adaptive advantage related to clinical outcome in heart disease. The molecular basis of myoadenylate deaminase deficiency in Caucasians has been attributed to a single mutant allele characterized by double C to T transitions at nucleotides +34 and +143 in mRNA enco…