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91.
Doménech-Carbó A Doménech-Carbó MT Gimeno-Adelantado JV Bosch-Reig F 《Analytical and bioanalytical chemistry》2006,385(8):1552-1561
A solid-state electrochemical application of the H-point standard addition method to the quantification of two depositable
metals A and B, which produce strongly overlapped stripping peaks, is described. The method is based on the mechanical transference
of mixtures of the solid sample plus a selected compound, of a reference depositable metal R, and of known amounts of a reference
material containing A or B, to paraffin-impregnated graphite electrodes. After a reductive deposition step, voltammograms
recorded for those modified electrodes immersed into a suitable electrolyte produce stripping peaks for the oxidation of all
of the metals deposited. Measurement of the currents at selected potentials in overlapping peaks corresponding to the stripping
of A and B permits the quantitation of these metals in the solid sample, while avoiding matrix effects. The method was applied
to the simultaneous determination of Pb and Sn in archaeological glazes using PbCO3 and SnO2 as standards and ZnO as a reference material.
相似文献
92.
José Carlos Díaz-Ramos Miguel Domínguez-Vázquez Cristina Vidal-Castiñeira 《Annals of Global Analysis and Geometry》2018,53(2):205-216
We show that an isoparametric submanifold of a complex hyperbolic plane, according to the definition of Heintze, Liu and Olmos’, is an open part of a principal orbit of a polar action. We also show that there exists a non-isoparametric submanifold of the complex hyperbolic plane that is isoparametric according to the definition of Terng’s. Finally, we classify Terng-isoparametric submanifolds of two-dimensional complex space forms. 相似文献
93.
In this paper we present a convergence analysis for the Nyström method proposed in [J Comput Phys 169 (1):80–110, 2001] for the solution of the combined boundary integral equation formulations of sound-soft acoustic scattering problems in three-dimensional space. This fast and efficient scheme combines FFT techniques and a polar change of variables that cancels out the kernel singularity. We establish the stability of the algorithms in the $L^2$ norm and we derive convergence estimates in both the $L^2$ and $L^\infty $ norms. In particular, our analysis establishes theoretically the previously observed super-algebraic convergence of the method in cases in which the right-hand side is smooth. 相似文献
94.
P. Domínguez A. Hernández G. Sienra 《Journal of Difference Equations and Applications》2013,19(7):1019-1032
We consider two classes of functions studied by Epstein [A.L. Epstein, Towers of finite type complex analytic maps, Ph.D. thesis, City University of New York, 1993] and by Herring [M.E. Herring, An extension of the Julia–Fatou theory of iteration, Ph.D. thesis, Imperial College, London, 1994], which have the Ahlfors' Property. We prove under some conditions on the Fatou and Julia sets that the singleton buried components are dense in the Julia set for these classes of functions. 相似文献
95.
AbstractOxide dispersion strengthened Fe14Cr and Fe14CrWTi alloys produced by mechanical alloying and hot isostatic pressing were subjected to isochronal annealing up to 1400 °C, and the evolution and thermal stability of the vacancy-type defects were investigated by positron annihilation spectroscopy (PAS). The results were compared to those from a non-oxide dispersion strengthened Fe14Cr alloy produced by following the same powder metallurgy route. The long lifetime component of the PAS revealed the existence of tridimensional vacancy clusters, or nanovoids, in all these alloys. Two recovery stages are found in the oxide dispersion strengthened alloys irrespective of the starting conditions of the samples. The first one starting at T > 750 °C is attributed to thermal shrinkage of large vacancy clusters, or voids. A strong increase in the intensity of the long lifetime after annealing at temperatures in the 800–1050 °C range indicates the development of new vacancy clusters. These defects appear to be unstable above 1050 °C, but some of them remain at temperatures as high as 1400 °C, at least for 90 min. 相似文献
96.
The creep behaviour and microstructure of two silicon nitride ceramics have been investigated. Compressive creep tests were performed at temperatures between 1450 and 1700°C at stresses between 6 and 90?MPa in an Ar atmosphere. The creep behaviour was characterized by a stress exponent lower than one for both materials, with an average value n?≈?0.6 over the whole range of stresses and temperatures, and with apparent activation energies between 470 and 530?kJ?mol?1. The study of the microstructural evolution revealed the absence of dynamic grain growth and, in some cases, evidence of grain rearrangement. Partial coalescence of cavities was observed only at the highest stress, but this did not result in accelerated creep. 相似文献
97.
José R. Mora Rosa M. Domínguez Armando Herize María Tosta Gabriel Chuchani 《Journal of Physical Organic Chemistry》2008,21(5):359-364
The gas‐phase elimination kinetics of 2,2‐diethoxyethyl amine and 2,2‐diethoxy‐N,N‐diethylethanamine (320–380 °C; 40–150 Torr) in a seasoned reaction vessel are homogeneous, unimolecular and obey a first‐order rate law. These elimination processes involve two parallel reactions. The first gives ethanol and the corresponding 2‐ethoxyethenamine. The latter compound further decomposes to ethylene, CO and the corresponding amine. The second parallel reaction produce ethane and the corresponding ethyl ester of an α‐amino acid. The following Arrhenius expressions are given as: For 2,2‐diethoxyethyl amine For 2,2‐diethoxy‐N,N‐diethylethanamine Comparative kinetic and thermodynamic parameters of the overall, the parallel and the consecutive reactions lead to consider two types of mechanisms in terms of a concerted polar cyclic transition state structures. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
98.
99.
Di Turo Francesca Parra Rafael Piquero-Cilla Joan Favero Gabriele Doménech-Carbó Antonio 《Journal of Solid State Electrochemistry》2019,23(3):771-781
Journal of Solid State Electrochemistry - Electrochemical impedance spectroscopy (EIS) and voltammetry of immobilized particles (VIMP) measurements using air-saturated mineral water and... 相似文献
100.