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Search Results: 1 - 10 of 190099 matches for " Agustin G. Asuero "
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Formulation of the System of Isohydric Solutions  [PDF]
Tadeusz Micha?owski, Agustin G. Asuero
Journal of Analytical Sciences, Methods and Instrumentation (JASMI) , 2012, DOI: 10.4236/jasmi.2012.21001
Abstract: The isohydricity (pH constancy) as the property referred to mixtures of acids or bases, is illustrated on a simple example of the solutions: HL (C0, mol/L) and HL (C mol/L) mixed according to titrimetric mode (pH titration). A new derivation of the Michalowski formula C0=C+C2·10PK1 expressing this property is presented, and its applicability for determination of pK1 = – logK1 value is indicated. The principle of the isohydric method of pK1 determination is also outlined.
A Potentiometric Evaluation of Stability Constants of Two-Step Overlapping Equilibria via a Bilogarithmic Hyperbolic Cosine Method  [PDF]
Samuel Beaumont, Julia Martin, Agustin G. Asuero
Journal of Analytical Sciences, Methods and Instrumentation (JASMI) , 2016, DOI: 10.4236/jasmi.2016.62005
Abstract: A bilogarithmic hyperbolic cosine method for the evaluation of overlapping formation constants at varying (or fixed) ionic strength is devised in this paper and applied to data reported in the analytical literature, i.e. succinic acid system, Cu(II)-glycine system and Ag(I)-aminobutan-1-ol system. The method is based on the linearization of the formation function ? = f(pH) or ? = f(pL) data. A theoretical slope of unity should be obtained thus proving the correctness of the assumed equilibria. An additional advantage of the bilogarithmic method proposed is that it provides a closed scale representation of Y and X unlike other plots. This paper forms part of an investigation into the uses of bilogarithmic methods and hyperbolic functions in parameter estimation. Methods based on the application of spectrophotometric measurements have been the subject of recent studies.
Thermodynamic Modelling of Dolomite Behavior in Aqueous Media
Tadeusz Micha owski,Agustin G. Asuero
Journal of Thermodynamics , 2012, DOI: 10.1155/2012/723052
Abstract: The compact thermodynamic approach to the systems containing calcium, magnesium, and carbonate species is referred to dissolution of dolomite, as an example of nonequilibrium ternary salt when introduced into aqueous media. The study of dolomite is based on all attainable physicochemical knowledge, involved in expressions for equilibrium constants, where the species of the system are interrelated. The species are also involved in charge and concentration balances, considered as constraints put on a closed system, separated from the environment by diathermal walls. The inferences are gained from calculations performed with use of an iterative computer program. The simulated quasistatic processes occurred under isothermal conditions, started at a preassumed pH0 value of the solution where dolomite was introduced, and are usually involved with formation of other solid phases. None simplifying assumptions in the calculations were made.
Inflection Points on Some S-Shaped Curves  [PDF]
Anna M. Micha?owska-Kaczmarczyk, Tadeusz Micha?owski, Agustin G. Asuero
Journal of Analytical Sciences, Methods and Instrumentation (JASMI) , 2014, DOI: 10.4236/jasmi.2014.41004

This paper refers to inflection point—the fundamental property of S-shaped curves. In this paper, the inflection points are related to pH titration curve pH = pH(V), and to the curve s = s(pH) involved with surface tension, s.

Formulation of Titration Curves for Some Redox Systems  [PDF]
Anna M. Micha?owska-Kaczmarczyk, Maciej Rymanowski, Agustin G. Asuero, Marcin Toporek, Tadeusz Micha?owski
American Journal of Analytical Chemistry (AJAC) , 2014, DOI: 10.4236/ajac.2014.513095
Abstract: The formalism realised according to the Generalised Approach to Electrolytic Systems (GATES) is presented and applied to typical redox systems known from the laboratory practice. In any redox system, the Generalized Electron Balance (GEB), perceived as the law of the matter conservation, is derivable from linear combination 2·f(O) – f(H) of elemental balances: f(O) for oxygen and f(H) for hydrogen. It is an equation linearly independent from other (charge and concentration) balances referred to an electrolytic redox system (aqueous media) of any degree of complexity, and named as the primary form of GEB and then denoted as pr-GEB. A compact equation for GEB is obtained from linear combination of 2·f(O) – f(H) with other (charge and concentration) balances. For a non-redox electrolytic system, of any degree of complexity, the balance 2·f(O) – f(H) is not an independent equation. In the derivation of GEB, all known components (species) of the system tested, taken in their real (i.e., hydrated) form, are involved in the balances, and none simplifying assumptions are needed. The redox systems are simulated with use of an iterative computer program.
A New Approach to Carbonate Alkalinity  [PDF]
Bogus?aw Pilarski, Anna M. Micha?owska-Kaczmarczyk, Agustin G. Asuero, Agnieszka Dobkowska, Monika Lewandowska, Tadeusz Micha?owski
Journal of Analytical Sciences, Methods and Instrumentation (JASMI) , 2014, DOI: 10.4236/jasmi.2014.42009

The article provides experimental data applied to the determination of carbonate alkalinity (CAM) according to modified Gran II functions. CAM is related to the mixtures NaHCO3 + Na2CO3 and Na2CO3 + NaOH. In addition to the determination of equivalence volumes, one of the main novelties of the proposed method is the possibility of determining the activity coefficient of hydrogen ions (γ). Moreover, CAM can be used to calculate the dissociation constants (K1, K2) for carbonic acid and the ionic product of water (KW) from a single pH titration curve. The parameters of the related functions are calculated according to the least squares method.

Fitting Nonlinear Calibration Curves: No Models Perfect  [PDF]
Julia Martin, Alberto Romero Gracia, Agustín G. Asuero
Journal of Analytical Sciences, Methods and Instrumentation (JASMI) , 2017, DOI: 10.4236/jasmi.2017.71001
Abstract: The study of the calibration of a series of compounds of environmental concern (six perfluoroalkyl compounds (perfluorooctane sulfonic acid and five perfluoroalkyl carboxylic acids), three preservatives (methyl-, ethyl- and propylparabens) and the brominated flame retardant hexabromocyclododecane) by LC-MS/MS has been carries out, with a view to their simultaneous determination in samples of environmental interest. In some cases nonlinear calibration curves are obtained, but restricting the concentration range a linear model may be used to fit the data. Residual analysis has been performed in order to verify which models fit the data better, opting for a compromise decision given the apparent complexity of residuals plots. As Box states there are no perfect models (but models that work better than others).
Vertebra Plana (Enfermedad de Calve): Relato de dos casos
Revista chilena de pediatría , 1955,
Alteraciones de la columna vertebral en el tétanos del ni o mayor
Revista chilena de pediatría , 1955,
Scientia Et Technica , 2006,
Abstract: A partir de este estudio se creó una propuesta para mejorar el proceso de secado de cereales, teniendo en cuenta que una mala gestión en este proceso, genera retrasos en producción, detrimento de la calidad del producto y por ende riesgos químicos, biológicos y físicos, poniendo en peligro la vida de las aves que se alimentan del producto terminado. Para tal efecto, se realizó un estudio analítico del proceso, encontrándose dos puntos críticos en particular: Una falta de homogeneidad en la humedad de los granos secos y prolongados tiempos de secado. Este estudio ocupó el segundo lugar en la convocatoria de ACAIRE.
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