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Electrochemical Behaviour and Determination of Cytarabine
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by D. Dogrukol, M. Tuncel
331-338
DOI: DOI: 10.4152/pea.199102331
An electroanalytical study of the cytarabine reduction process at a dropping mercury electrode in aqueous supporting electrolyte solution using direct current polarographic technique has been carried out. The optimum parameters were found as 1000 dyne.cnr2 pressure on the mercury reservoir, Is drop time, 4 mV.s"1 scan rate and 5.50-6.60 pH range. The reversibility of the reduction on the mercury electrode was ascertained as quasi-reversible and the polarographic current was mainly diffusion controlled. The results obtained by DC, SIAP and DP polarography allowed a method developed for the determination of cytarabine in the lxlO-4 - 5xl04 mol.L"1 concentration range. Good results were obtained by applying the DC polarographic technique to the determination of cytarabine in a pharmaceutical preparation.
Étude des Processus Cinetico-Chimiques de la Metallisation avec du Cuivre dans ABS (Acronitrile-Butadiene-Stirène)
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by J. L. Polo, R. Guzman, A. M. Martinez
339-354
DOI: DOI: 10.4152/pea.199102339
The experimental conclusions on the
chemical-kinetic process of the chemical plating on ABS surface, one of the plastics materials more widely used, are presented, describing each step of the process
Potential Oscillations by the Anodic Methanol Oxidation
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by Aníbal Armando Inocêncio, Maria Alice Inocêncio
355-372
DOI: DOI: 10.4152/pea.199102355
In the anodic methanol oxidation in aqueous sulphuric acid on smooth R-electrodes using the chronopotentyometric method, oscillations of potential in the V=V(t)-curves have been observed. The evolution of such potential oscillations with the value of the current impulse imposed on the electrodes has been discussed and a reaction mechanism of the methanol oxidation has been proposed in accordance with the experimental results
by Ana Maria Oliveira Brett, M. Helena Gil, A. Paula Piedade
7-10
DOI: DOI: 10.4152/pea.199101007
Current/Potential Studies on Tetraheme Cytochromes C3.
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by C. Moreno, A. Campos, M. Teixeira et al.
11-14
DOI: DOI: 10.4152/pea.199101011
Reaction of Pyridoxal and Pyridoxal 5-Phosphate with Hexylamine. Comparative Electrochemical and Spectrophotometric Studies
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by T. Pineda, M. Blázquez, J. M. Sevilla et al.
15-18
DOI: DOI: 10.4152/pea.199101015
The Effect of Ta Ion Implantation on the Aqueous Corrosion Resistance of M50 Bearing Steel
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by C M. Rangel, M. H. Simplício, A. C. Consiglieri
19-22
DOI: DOI: 10.4152/pea.199101019
Corrosion Products of Low Alloy Steel under Wet-Dry Cycling Conditions
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by J. Davalos, J. F. Marco, M. Gracia et al.
23-26
DOI: DOI: 10.4152/pea.199101023
The corrosion products formed on weathering steel and pure iron exposed to a wet-dry cycled SO2~atmosphere have been studied by means of reflection (CEMS) and transmission Mossbauer spectroscopy and X-ray diffraction. After 48 days of exposure, rusts of both materials exhibit different morphologies. FeS03.3H20, FeS04.nH20 and amorphous ferric oxyhydroxides (probably ferrihydrite and/or a-FeOOH of small particle size) are the constituents of both rusts. The main differences between the corrosion products of both materials are related with the concentration of Fe2* species and the crystallinity and/or particle size of ferric oxyhydroxides. The presence of Fe?+ species in 48 day-old rusts is attributed to the effect of the wet-dry cycling conditions.
Influence of Imidazoles in the Deposition Velocity of Copper on non Conductors by Electroless
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by M. M. Dávila, C. Martinez, H. Scholl et al.
27-30
DOI: DOI: 10.4152/pea.199101027
The effect o-f the imidazoles I-III (1) on the deposition velocity o-f cooper on phenolic and epoxy resins has been studied. It is shown that these substances affect the stability of the cooper electroless baths in the temperature interval 25-52 ºC.
Modificações na Superfície do Eléctrodo de Irídio Induzidas por Polarização Electroquímica
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by M.Teresa S. Portela, M. Irene S. Lopes, Inês T.E. Fonseca
31-34
DOI: DOI: 10.4152/pea.199101031
Influence of «Pseudomonas Aeruginosa» on the Pitting Corrosion of a 18/8 Stainless Steel in Phosphate Borate in the Presence of NaCl. I - Chloride Anions Action
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by P. Esparza, J. Morales, M. P. Arevalo et al.
35-38
DOI: DOI: 10.4152/pea.199101035
In solution containing chloride anions, the pitting corrosion can be obtained when the electrode potential exceeds a certain critical value (Ep). The initiation of pitting corrosion has been considered as a rare even both in space and time and consequently, it can be treated as a statistical phenomenon (1-4). The pitting corrosion of. 304 stainless steel (304 SS) in a strong buffered chloride ions containing medium has been studied by using the potentiodynamic and potentiostatic techniques complemented with scanning electron microscopy observations.
Influence of «Pseudomonas Aeruginosa» on the Pitting Corrosion of a 18/8 Stainless Steel in Phosphate Borate in the Presence of NaCl. II - Microbiologically Influence Corrosion
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by J. Morales, P. Esparza, M. P. Arevalo
39-42
DOI: DOI: 10.4152/pea.199101039
The Corrosion and Passivity of Copper in Aqueous Solutions Containing Sodium Perchlorate
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by R. M. Souto, M. Pérez Sánchez, M. Barrera et al.
43-47
DOI: DOI: 10.4152/pea.199101043
Plasma Sprayed Ceramic Coatings on St 37 Steel Substrates
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by V. Costa, C. M. Rangel, L. F. Cruz et al.
49-53
DOI: DOI: 10.4152/pea.199101049
Estúdio del Proceso de Electrodeposición de Piorno en los Banos PbCl2-xNaCl Fundidos
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by Y. Castrillejo, S. Palmero, M. L. Matía et al.
55-58
DOI: DOI: 10.4152/pea.199101055
Informação sobre a Natureza das Estruturas Coordenadoras dos Ácidos Fúlvicos Obtida por Comparação de Curvas de Titulação na Presença de Catiões Metálicos com Curvas Simuladas para Modelos
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by Adélio A. S. C. Machado, Joaquim C. G. Esteves da Silva
59-63
DOI: DOI: 10.4152/pea.199101059
Cathodic Stripping Voltammetry at a Hanging Mercury Drop Electrode: Use of Polyaminoacid Films, Copper (II), Derivatization of Large Molecules and Sample Cleanup
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by Arnold G. Fogg, Josino C. Moreira, F. Nil Ertas
65-70
DOI: DOI: 10.4152/pea.199101065
Adsorptive Stripping Voltammetry: Adsorption of Dioxime Ligands and Cobalt and Nickel Complexes at Mercury Thin-Film Electrodes
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by Christopher M. A. Brett, Ana Maria Oliveira Brett, Jorge L. C. Pereira
71-74
DOI: DOI: 10.4152/pea.199101071
Estúdio Voltamperometrico de los Complejos Cd-Ligandos Inorgânicos a Bajas Concentraciones
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by E. Barrado, R. Pardo, M. Herguedas et al.
75-78
DOI: DOI: 10.4152/pea.199101075
Interaction of 6-Aminopurine (Adenine) and of 6-Dimetylaminopurine with Copper Ions in Aqueous Medium. Formation of Cu(I) Complexes
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by J. E. Simão, H. M. Tavares
79-83
DOI: DOI: 10.4152/pea.199101079
Differential pulse polarography (DPP) has been used to elucidate the interaction of adenine with copper and the interaction of 6-dimethyladenine with copper using sulphuric acid 0.1 M as supporting electrolyte. As has been verified with other purines in this and other media, copper (II) ions are reduced at the mercury electrode in two stages via an intermediate valency state, and two reduction peaks may be observed. Taking into account the variation of the differences (AEp) between the peak potential of each complex and the metal ion with the logarithm of concentration of adenine and the 6-dimethyladenine, respectively, we can conclude that the numbers of the ligands are equal in the two cases and the stability constants are of the same order of magnitude
