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Dumitru Oancea Valentin Munteanu Domnina Razus 《Journal of Thermal Analysis and Calorimetry》2010,102(3):993-1000
The transient response of the input power necessary to maintain isothermal conditions after a step temperature perturbation
applied to a platinum wire immersed in a gaseous fuel/air mixture allows for the measurement of the reaction heat flow rate,
directly related to the rate of the catalytic combustion. The S-shaped variation of this rate in time is employed to evaluate
the induction period of the catalytic ignition. The effect of mixture composition, total pressure, and catalyst temperature
on the induction period for the catalytic ignition of lean to stoichiometric n-pentane/air mixtures on isothermally heated platinum wire is reported and discussed. The mixture composition was varied between
1.40 and 2.56% n-pentane in air, the total pressure between 20 and 101 kPa, and the wire temperature between 470 and 600 K. The reaction rates,
turnover frequencies, overall and partial reaction orders, and activation energies were determined from the analysis of the
obtained results and compared to other reported data. 相似文献
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We determine the rank generating function, the zeta polynomial and the M?bius function for the poset NC
(B)
(p, q) of annular non-crossing partitions of type B, where p and q are two positive integers. We give an alternative treatment of some of these results in the case q = 1, for which this poset is a lattice. We also consider the general case of multiannular noncrossing partitions of type
B, and prove that this reduces to the cases of non-crossing partitions of type B in the annulus and the disc. 相似文献
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Adina Raducan Alexandra Olteanu Mihaela Puiu Dumitru Oancea 《Central European Journal of Chemistry》2008,6(1):89-92
The kinetics of the reaction between malachite green (MG) and sodium hydroxide (MG fading) was studied using a spectrophotometric
method in the presence of two cationic surfactants, cetyl-benzyl-dimethyl-ammonium chloride (CBDAC) and hexadecyl-trimethylammonium
bromide (HTAB) and one anionic surfactant, sodium dodecyl sulphate (SDS) at concentrations below and above critical micellar
concentrations. The cationic surfactants have a catalytic effect, while the anionic surfactant has an inhibitory effect on
the reaction. A kinetic model describing the influence of surfactant on reaction rate was developed. The results are discussed
on the basis of electrostatic and hydrophobic interactions between the kinetic micelles and malachite green.
相似文献
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Jeanina Pandele Cusu Adina Magdalena Musuc Mihaela Matache Dumitru Oancea 《Journal of Thermal Analysis and Calorimetry》2012,110(3):1259-1266
In this study, the thermal stability and exothermal decomposition of some ketone-2,4-dinitrophenylhydrazones have investigated using the DSC technique. The synthesized and purified crystalline solids are thermally stable and start to decompose after melting. Non-isothermal DSC curves, recorded at several heating rates, were used to evaluate the melting properties and the kinetics of thermal decomposition. The isoconversional and model-fitting methods were applied to determine the activation parameters from the common analysis of multiple curves measured at different heating rates. Based on the results of the model??free method, a kinetic model was derived, and the kinetic parameters were obtained by means of a multivariate nonlinear regression. The results are discussed in relation to the effect of the ketone structure. 相似文献
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Alexandru Oancea 《Mathematische Annalen》2006,334(1):65-89
We prove the Künneth formula in Floer (co)homology for manifolds with restricted contact type boundary. We use Viterbo's definition
of Floer homology, involving the symplectic completion by adding a positive cone over the boundary. The Künneth formula implies
the vanishing of Floer (co)homology for subcritical Stein manifolds. Other applications include the Weinstein conjecture in
certain product manifolds, obstructions to exact Lagrangian embeddings, existence of holomorphic curves with Lagrangian boundary
condition, as well as symplectic capacities.
Supported by ENS Lyon, école Polytechnique (Palaiseau) and ETH (Zürich). 相似文献
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Maria Mitu Domnina Razus Dumitru Oancea 《Journal of Thermal Analysis and Calorimetry》2018,131(1):175-181
The present work aims to investigate several kinetic aspects of catalytic combustion of the stoichiometric propane–air mixture on a platinum wire in the presence of progressive CO2 dilution, using a micro-calorimetric method. The method allowed the determination of the induction periods and of the reaction rates during transient and steady-state regimes at different initial pressures P 0 (10–101 kPa), wire temperatures T w (470–575 K) and gas-phase composition. The kinetic parameters were evaluated from regression analysis using empirical and mechanistic models. The dilution with CO2 of the stoichiometric propane–air mixture (4.02% propane) was 10, 20, 30, 40, 50%. For additions equal to or greater than 23%, the gaseous system is outside the flammability limits reported in the literature. The kinetic characteristics of the catalytic combustion remain similar for the whole range, even for 50% CO2 addition when the propane concentration in mixture diminishes to 2%, a concentration smaller than the lower explosion limit in air in normal conditions. 相似文献
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The kinetics of the auto-oxidation of 2-aminophenol (OAP) to 2-amino-phenoxazin-3-one (APX) was followed in air-saturated
aqueous solutions and the influence of temperature and pH on the auto-oxidation rate was studied. The kinetic analysis was
based on a spectrophotometric method following the increase of the absorbance of APX. The process follows first order kinetics
according to the rate law—d[OAP]/dt=k′[OAP]. The experimental data, within the pH range 4–9.85, were analyzed using both differential
and incremental methods. The temperature variation of the overall rate constant was studied at pH=9.85 within the range 25–50°C
and the corresponding activation energy was evaluated. 相似文献
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