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Search Results: 1 - 10 of 613750 matches for " M. L. Dominguez-Pati?o "
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Corrosion Inhibition of Carbon Steel in Acidic Mediaby Using Actinidia deliciosa (Kiwifruit) Extract  [PDF]
M. I. Arias-Montoya, G. F. Dominguez-Patio, J. G. Gonzalez-Rodriguez, J. A. Dominguez-Patio, M. L. Dominguez-Patio
Advances in Materials Physics and Chemistry (AMPC) , 2015, DOI: 10.4236/ampc.2015.511045
Abstract: The corrosion inhibition of 1018 carbon steel in 0.5 M H2SO4 by using Actinidia deliciosa (Kiwifruit) peel extract has been investigated by using potentiodynamic polarization curves and electro-chemical impedance spectroscopy. Two kinds of extracts are investigated, one from the tender, and another one from ripe Actinidia deliciosa. Concentrations include 0, 25, 50, 75, and 100 ppm at room temperature. Results indicate that both kind of extracts acted as good corrosion inhibitors, is more efficient in the ripe extract. Corrosion inhibition efficiency increases with increasing its concentration for ripe extract, whereas for the tender Actinidia deliciosa, the higest inhibitor efficiency is obtained by adding 25 ppm and decresaing with a further increase in its concentration. Both extracts improve the passive film properties by decreasing the passive current density values. It is found that the corrosion inhibition is due to the presence of heteroatoms present in Actinidia deliciosa, mainly quercitine, which is physically adsorbed in the steel following a Frumkin type of adsorption isotherm which forms a protective film.
A Study of Eruca vesicaria, Bromelia hemisphaerica and Erythrina americana as Green Corrosion Inhibitors for Carbon Steel in Sulfuric Acid  [PDF]
M. J. Garcia-Ramirez, G. F. Dominguez Patio, J. G. Gonzalez-Rodriguez, M. L. Dominguez-Patio, J. A. Dominguez-Patio
Advances in Materials Physics and Chemistry (AMPC) , 2016, DOI: 10.4236/ampc.2016.62002
Abstract: A study of Eruca vesicaria, Bromelia hemisphaerica and Erythrina americana as eco-friendly corrosion inhibitors for 1018 carbon steel in 0.5 M H2SO4 has been carried out by using weight loss tests, potentiodynamic polarization curves and electrochemical impedance spectroscopy measuremnts. Results have shown that the three extracts performed as good corrosion inhibitors, but the Eruca vesicaria exhibited the best performance followed by Erythrina americana. The three inhibitors formed a protective, passive film which protected the steel from corrosion. This was because they contain antioxidants present in their molecular structure with heteroatoms such as N, C and O like phenols, amino acids, etc., which react with metal and environment to form the protective film.
Electron paramagnetic resonance in the research of defect formation and thermal processes during grinding of ZnO powders
Kakazey M.,Vlasova M.,Dominguez-Patio M.,Dominguez-Patio G.
Science of Sintering , 2004, DOI: 10.2298/sos0402065k
Abstract: This work shows some possibilities for using electron paramagnetic resonance in an experimental study of the role of mechanothermal effects in the formation of defect structures in dispersed systems during prolonged mechanical treatment of ZnO powders. The use of EPR for this purpose is based on the known fact that initiation of a number of paramagnetic centers occurs during mechanical treatment of some materials. Such centers can serve as EPR-sondes of different thermal processes appearing during mechanical treatment of systems containing ZnO.
Structural-phase transformations in bentonite after acid treatment
Vlasova M.,Dominguez-Patio G.,Kakazey N.,Dominguez-Patio M.
Science of Sintering , 2003, DOI: 10.2298/sos0303155v
Abstract: The methods of X-ray diffraction, Fourier transform infra-red spectroscopy (FTIR), X-ray microanalysis, electron microscopy, BET and cation exchange capacity (CEC) were used for investigation of the structural-phase transformations in bentonite under the influence of hydrochloric acid and temperature treatment (100-800oC). It is established that in HCl medium during temperature treatment, dehydration and dehydroxilation of montmorillonite occur. The presence of gypsum and barium chloride results in an intercalation of interlayer space of montmorillonite by Ca and Ba ions Temperature treatment of intercalated montmorillonite leads to the formation of pores.
Corrosion Behavior of Fe40Al Alloy with Additions of Ti, Ag, and Cr in Molten KCl+
R. Ademar,J. G. Gonzalez-Rodriguez,J. Uruchurtu,J. Porcayo-Calderon,V. M. Salinas-Bravo,G. Dominguez-Patio,A. Bedolla-Jacuinde
International Journal of Corrosion , 2012, DOI: 10.1155/2012/146486
Abstract: The effect of 2.5?at.% Cr, Ti, and Ag on the corrosion behavior of Fe40Al intermetallic alloy in KCl-ZnCl2 (1?:?1?M) at 670°C has been evaluated by using electrochemical techniques. Techniques included potentiodynamic polarization curves, linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) measurements. Results have shown that additions of both Cr and Ti were beneficial to the alloy, since they decreased its corrosion rate, whereas additions of Ag was detrimental, since its additions increased the corrosion rate, although the alloy was passivated by adding Ag or Cr. The best corrosion performance was obtained with the addition of Cr, whereas the highest corrosion rate was obtained by adding Ag. This is explained in terms of the stability of the corrosion products formed film. 1. Introduction Sodium and potassium impurities present in the form of chloride or sulfates are very corrosive constituents under certain combustion conditions such as waste incinerators and biomass-fired boilers [1, 2]. Early failure of the thermal components frequently occurs due to the complex reactions between the metallic materials and the hostile combustion environment. Incineration has become a viable technology for disposing of various types of wastes, including municipal, hospital, chemical, and hazardous. Problems with process equipment resulting from fireside corrosion have been frequently encountered in incinerators. The major problem is the complex nature of the feed (waste) as well as corrosive impurities which form low-melting point compounds with heavy and alkali metal chloride which prevents the formation of protective oxide scales and then causes an accelerated degradation of metallic elements [1]. In particular, under reducing conditions such as those typical of the operation of waste gasification plants or even under localized reducing conditions, which frequently arise in the case of incorrect operation of waste incineration systems, it is difficult to form protective oxide scales such as Cr2O3, SiO2, and Al2O3 on the surface of structural materials. Thus, the corrosion attack can be further enhanced under reducing atmospheres in the presence of salt deposits [2]. The effect of individual KCl, NaCl, and their mixtures with heavy metal chlorides or sulfates on the corrosion behavior of a series of alloy systems has been studied in detail so far [3–9]. It is generally realized that Cr is not as effective element for corrosion resistance of Fe-base and Ni-based alloys due to chloride attack. In contrast, alumina- (Al2O3) forming
Corrosion Inhibition of Carbon Steel in 0.5?M H2SO4 by Phtalocyanine Blue
J. C. Valle-Quitana,G. F. Dominguez-Patio,J. G. Gonzalez-Rodriguez
ISRN Corrosion , 2014, DOI: 10.1155/2014/945645
Abstract: Phthalocyanine blue dye has been investigated as a carbon steel corrosion inhibitor in 0.5?M sulfuric acid by using polarization curves, electrochemical impedance spectroscopy, and gravimetric tests. Dye concentrations included 0, 100, 200, 400, 600, 800, and 1000?ppm, whereas testing temperatures were 25, 40, and 60°C. Results indicated that phtalocyanine blue is a good corrosion inhibitor with its efficiency increasing with the concentration up to 40°C, but it increases at 60°C. Inhibitor improves the passive film properties and it forms an adherent, compact, protective film, acting, therefore, as an anodic-type inhibitor. At 25 and 40°C the corrosion process was under charge transfer, whereas at 60°C the adsorption/desorption of some species from the metal surface controlled the corrosion process. 1. Introduction Organic compounds containing atoms such as nitrogen, sulphur, and oxygen are commonly used to reduce the corrosion attack on steel in acidic media. These compounds adsorb on the metal surface, block the active sites on the surface, and thereby reduce the corrosion process [1–6]. The inhibiting action of such compounds is based on the adsorption ability of their molecules, where the resulting adsorption film isolates the metal from the aggressive media. The corrosion inhibition of organic compounds is related to their adsorption properties. Adsorption depends on the nature and the state of the metal surface, on the type of corrosive environment, and on the chemical structure of the inhibitor [7]. Studies report that the adsorption of organic inhibitors mainly depends on some physicochemical properties of the molecule, related to its functional groups, to the possible steric effects and electronic density of donor atoms; adsorption is suppose, also to depend on the possible interaction of the -orbitals of the inhibitor with the d-orbitals of the surface atoms, which induce greater adsorption of the inhibitor molecules onto the surface of metal, leading to the formation of a corrosion protection film [8]. Recently, there has been a lot of attention paid to the use of organic dyes as potential corrosion inhibitors for different metalsenvironments [9–24]. Thus, Oguzie evaluated the use of Congo red [9], methylene blue [10], indigo blue [11], safranin-o, thymol blue, and fluorescein [12] as corrosion inhibitors for mild steel in acidic media, although in some cases they evaluated these dyes for aluminum in hydrochloric acid [13]. Alizarin yellow and Bromophenol blue have been used also but now studying the synergistic effect of iodide ions for the
Corrosion inhibition of carbon steel by extract of Buddleia perfoliata
ROY LOPES-SESENES,JOSE GONZALO GONZALEZ-RODRIGUEZ,GLORIA FRANCISCA DOMINGUEZ-PATIO,ALBERTO MARTINEZ-VILLAFA?E
Journal of Electrochemical Science and Engineering , 2012,
Abstract: Buddleia perfoliata leaves extract has been investigated as a carbon steel corrosion inhibitor in 0.5 M sulfuric acid by using polarization curves, electrochemical impedance spectroscopy and weight-loss tests at different concentrations (0, 100, 200, 300, 400 and 500 ppm) and temperatures, namely 25, 40 and 60 °C. Results showthat inhibition efficiency increases as the inhibitor concentration increases, decreases with temperature, and reaches a maximum value after 12 h of exposure, decreasing with a further increase in the exposure time. It was found that the inhibitory effect is due to the presence of tannines on this extract.
El ensayo de micronúcleos como medida de inestabilidad genética inducida por agentes genotóxicos
Zalacain,M.; Sierrasesúmaga,L.; Patio,A.;
Anales del Sistema Sanitario de Navarra , 2005, DOI: 10.4321/S1137-66272005000300007
Abstract: human genetic integrity is compromised by the intense industrial activity, which emphasizes the importance to determine an "acceptable" genetic damage level and to carry out routine genotoxicity assays in the populations at risk. micronuclei are cytoplasmatic bodies of nuclear origin which correspond to genetic material that is not correctly incorporated in the daughter cells in the cellular division; they reflect the existence of chromosomal aberrations and are originated by chromosomal breaks, replication errors followed by cellular division of the dna and/or exposure to genotoxic agents. there are several factors able to modify the number of micronuclei present in a given cell, among them are age, gender, vitamins, medical treatments, daily exposure to genotoxic agents, etc. the cytogenetic assay for the detection of micronuclei (cbmn: cytokinesis-block micronucleus) is based on the use of a chemical agent, cytochalasin-b, which is able to block cytocinesis but allowing the nuclear division, therefore yielding binucleated and monodivided cells. the micronuclei scoring is performed on 1000 binucleated cells and the starting sample may vary, although most studies are performed on peripheral blood lymphocytes. the micronuclei assay is considered a practical, universally validated and technically feasible protocol which is useful to evaluate the genetic instability induced by genotoxic agents.
El ensayo de micronúcleos como medida de inestabilidad genética inducida por agentes genotóxicos The cytogenetic assay as a measure of genetic instability induced by genotoxic agents
M. Zalacain,L. Sierrasesúmaga,A. Patio
Anales del Sistema Sanitario de Navarra , 2005,
Abstract: La integridad genética de la población humana se encuentra comprometida por la gran actividad industrial; por lo que es importante determinar qué se conoce como un nivel "aceptable" de da o genético y realizar ensayos de genotoxicidad de manera rutinaria en poblaciones de riesgo. Los micronúcleos son cuerpos citoplasmáticos de naturaleza nuclear, se corresponden con material genético no incorporado correctamente a las células hijas durante la división celular, reflejan aberraciones cromosómicas y se originan por roturas cromosómicas, por errores durante la replicación y posterior división celular del ADN y/o por la exposición a agentes genotóxicas. Existen factores capaces de influir o modificar el número de micronúcleos presentes en una célula (edad, género, vitaminas, tratamientos médicos, exposición diaria a agentes genotóxicos, etc.). El ensayo citogenético para la detección de micronúcleos (CBMN: cytokinesis-block micronucleus) se basa en la utilización de un agente químico, denominado citocalasina-B capaz de impedir la citocinesis permitiendo la división nuclear proporcionando a las células un aspecto de células binucleadas monodivididas. El recuento de micronúcleos se realiza sobre 1.000 células binucleadas y la muestra de partida puede variar aunque lo óptimo es el uso de linfocitos aislados de sangre periférica. El ensayo de micronúcleos está considerado como un ensayo práctico, universalmente validado y accesible tecnológicamente, útil para evaluar la inestabilidad genética inducida por agentes genotóxicos. Human genetic integrity is compromised by the intense industrial activity, which emphasizes the importance to determine an "acceptable" genetic damage level and to carry out routine genotoxicity assays in the populations at risk. Micronuclei are cytoplasmatic bodies of nuclear origin which correspond to genetic material that is not correctly incorporated in the daughter cells in the cellular division; they reflect the existence of chromosomal aberrations and are originated by chromosomal breaks, replication errors followed by cellular division of the DNA and/or exposure to genotoxic agents. There are several factors able to modify the number of micronuclei present in a given cell, among them are age, gender, vitamins, medical treatments, daily exposure to genotoxic agents, etc. The cytogenetic assay for the detection of micronuclei (CBMN: cytokinesis-block micronucleus) is based on the use of a chemical agent, cytochalasin-B, which is able to block cytocinesis but allowing the nuclear division, therefore yielding binucleated and monodivided
Evolution, nucleosynthesis and yields of low mass AGB stars
S. Cristallo,O. Straniero,R. Gallino,L. Piersanti,I. Dominguez,M. T. Lederer
Physics , 2009, DOI: 10.1088/0004-637X/696/1/797
Abstract: The envelope of thermally pulsing AGB stars undergoing periodic third dredge-up episodes is enriched in both light and heavy elements, the ashes of a complex internal nucleosynthesis involving p, alpha and n captures over hundreds of stable and unstable isotopes. In this paper, new models of low-mass AGB stars (2 Msun), with metallicity ranging between Z=0.0138 (the solar one) and Z=0.0001, are presented. Main features are: i) a full nuclear network (from H to Bi) coupled to the stellar evolution code, ii) a mass loss-period-luminosity relation, based on available data for long period variables, and ii) molecular and atomic opacities for C- and/or N-enhanced mixtures, appropriate for the chemical modifications of the envelope caused by the third dredge up. For each model a detailed description of the physical and chemical evolution is presented; moreover, we present a uniform set of yields, comprehensive of all chemical species (from hydrogen to bismuth). The main nucleosynthesis site is the thin 13C pocket, which forms in the core-envelope transition region after each third dredge up episode. The formation of this 13C pockets is the principal by-product of the introduction of a new algorithm, which shapes the velocity profile of convective elements at the inner border of the convective envelope: both the physical grounds and the calibration of the algorithm are discussed in detail. The final surface compositions of the various models reflect the differences in the initial iron-seed content and in the physical structure of AGB stars belonging to different stellar populations. The agreement with the observed [hs/ls] index observed in intrinsic C stars at different [Fe/H] is generally good.
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