Electrochemical behaviour of copper in aqueous moderate alkaline media, containing sodium carbonate and bicarbonate, and sodium perchlorate

The voltammetric polarization of Cu specimens in Na2CO3, NaHCO3 and NaClO4 solutions (8-12pH range) has been investigated. Voltammetry data were complemented with SEM and electron microprobe analysis. Results are found to be in agreement with the passivation model developed for Cu in plain NaOH solutions. For the latter the process can be described in terms of two steps, namely, at low potentials the initial formation of a Cu2O thin layer followed by the growth of a massive Cu2O layer, and at higher potentials the appearance of a CuO-Cu(OH)2 layer. These processes are accompanied by the formation of soluble Cu species. Beyond a certain potential which increases with the solution pH, copper pitting takes place. This model can be extended to Cu in carbonate/bicarbonate containing solutions by considering that Cu carbonates precipitate as long as soluble ionic Cu species are produced, without interfering appreciably with the formation of Cu oxides. The appearance of copper carbonate species is enhanced when pitting corrosion sets in. The precipitation of Cu carbonates occurs principally around pits. Cu pitting, although it is observed for all solutions, becomes more noticeable at the lowest pH values. At a constant pH, the density of pits increases in the order NaClO4 > NaHCO3 > Na2CO3. The influence of the electrolyte composition on Cu pitting is closely related to the blockage capability for pit nucleation and growth of the corresponding copper salts. Passivation in the Cu2O-Cu(OH)2 region hinders pitting corrosion.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA)Facultad de Ciencias Exacta

Electrochemical behaviour of copper in aqueous moderate alkaline media, containing sodium carbonate and bicarbonate, and sodium perchlorate

The voltammetric polarization of Cu specimens in Na2CO3, NaHCO3 and NaClO4 solutions (8-12pH range) has been investigated. Voltammetry data were complemented with SEM and electron microprobe analysis. Results are found to be in agreement with the passivation model developed for Cu in plain NaOH solutions. For the latter the process can be described in terms of two steps, namely, at low potentials the initial formation of a Cu2O thin layer followed by the growth of a massive Cu2O layer, and at higher potentials the appearance of a CuO-Cu(OH)2 layer. These processes are accompanied by the formation of soluble Cu species. Beyond a certain potential which increases with the solution pH, copper pitting takes place. This model can be extended to Cu in carbonate/bicarbonate containing solutions by considering that Cu carbonates precipitate as long as soluble ionic Cu species are produced, without interfering appreciably with the formation of Cu oxides. The appearance of copper carbonate species is enhanced when pitting corrosion sets in. The precipitation of Cu carbonates occurs principally around pits. Cu pitting, although it is observed for all solutions, becomes more noticeable at the lowest pH values. At a constant pH, the density of pits increases in the order NaClO4 > NaHCO3 > Na2CO3. The influence of the electrolyte composition on Cu pitting is closely related to the blockage capability for pit nucleation and growth of the corresponding copper salts. Passivation in the Cu2O-Cu(OH)2 region hinders pitting corrosion.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA)Facultad de Ciencias Exacta

Cytotoxicity of three new triazolo-pyrimidine derivatives against the plant trypanosomatid: Phytomonas sp isolated from Euphorbia characias

There is no effective chemotherapy against diseases caused by Phytomonas sp., a plant trypanosomatid responsible for economic losses in major crops. We tested three triazolo-pyrimidine complexes [two with Pt(II), and another with Ru(III)] against promastigotes of Phytomonas sp. isolated from Euphorbia characias. The incorporation of radiolabelled precursors, ultrastructural alterations and changes in the pattern of metabolite excretion were examined. Different degrees of toxicity were found for each complex: the platinun compound showed an inhibition effect on nucleic acid synthesis, provoking alterations on the levels of mitochondria, nucleus and glycosomes. These results, together with others reported previously in our laboratory about the activity of pyrimidine derivatives, reflect the potential of these compounds as agents in the treatment of Phytomonas sp.Financial support Universidad de Granada (Spain), grant BIO 2000-1429

Experimental and Computational Studies on the Interaction of a Dansyl-Based Fluorescent Schiff Base Ligand with Cu2+ Ions and CuO NPs

We studied the interaction of Cu2+ ions and CuO nanoparticles with the fluorescent Schiff base ligand H3L, which derives from the condensation of 4-formyl-3-hydroxybenzoic acid with N-(2-aminobenzyl)-5-(dimethylamino)naphthalene-1-sulfonamide (DsA). A detailed assignment of the most significant bands of the electronic and infrared spectra of H3L and DsA was performed using DFT methods, based on both crystal structures. The affinity of H3L to react with Cu2+ ions in solution (KB = 9.01 103 L mol-1) is similar to that found for the Cu2+ ions present on the surface of CuO NPs (KB = 9.84 103 L mol-1). Fluorescence spectroscopic measurements suggest five binding sites for H3L on the surface of the CuO NPs used. The µ-XRF analysis indicates that a polycrystalline sample of CuO-H3L NPs contains 15:1 Cu:S molar ratio (CuO:H3L). ATR-FTIR spectroscopy, supported by DFT calculations, showed that the HL2- (as a phenolate and sulfonamide anion) is coordinated to superficial Cu2+ ions of the CuO NPs through their azomethine, sulphonamide, and phenolic groups. A solution of H3L (126 ppb) shows sensitive responses to CuO NPs, with a limit of detection (LOD) of 330 ppb. The working range for detection of CuO NPs with [H3L] = 126 ppb was 1.1-9.5 ppm. Common metal ions in water, such as Na+, K+, Mg2+, Ca2+, Fe3+, and Al3+ species, do not interfere significantly with the detection of CuO NPs.This research was funded by the Ministerio de Ciencia, Innovación y Universidades (RTI2018-099222-B-I00) and Interreg Atlantic Area, Poctep (ACUINANO Project). Authors would like to thank the use of RIAIDT-USC analytical facilities, and the support provided for this work.S

DESIGN AND INTEGRATION OF A HUMAN-ROBOT PHYSICAL INTERACTION PLATFORM WITH PURPOSES OF MEDICAL DIAGNOSIS AND REHABILITATION OF UPPER LIMB

In this paper a human-robot physical interaction system with purposes of diagnosis and rehabilitation of upper limb is proposed.Anunderactuatedhaptic device with six degrees of freedom is used, with low inertia and low joint friction.Adaptive control technique is used for passive haptic guidance and active exploration, in order to compensate the dynamic uncertainty of the human operator in the loop.To validate the experimental platform, a procedure is established with three steps: i) knowledge of the haptic interface (interaction with the kinematic virtual environment), ii) navigation in a virtual pipe with changes in the geometric characteristics (verification of position, velocity, collisions and runtime), and iii) haptic guidance in a structured path based on a clinical protocol (study of convergence and energy).Environmental conditions such as temperature, humidity, lighting and noise are characterizedwith purposes to define experimental conditions.In this work, we assess based on the NASA-TLX protocol,the workload perception of simple temporal-spatial tasks

DESIGN AND INTEGRATION OF A HUMAN-ROBOT PHYSICAL INTERACTION PLATFORM WITH PURPOSES OF MEDICAL DIAGNOSIS AND REHABILITATION OF UPPER LIMB

In this paper a human-robot physical interaction system with purposes of diagnosis and rehabilitation of upper limb is proposed.Anunderactuatedhaptic device with six degrees of freedom is used, with low inertia and low joint friction.Adaptive control technique is used for passive haptic guidance and active exploration, in order to compensate the dynamic uncertainty of the human operator in the loop.To validate the experimental platform, a procedure is established with three steps: i) knowledge of the haptic interface (interaction with the kinematic virtual environment), ii) navigation in a virtual pipe with changes in the geometric characteristics (verification of position, velocity, collisions and runtime), and iii) haptic guidance in a structured path based on a clinical protocol (study of convergence and energy).Environmental conditions such as temperature, humidity, lighting and noise are characterizedwith purposes to define experimental conditions.In this work, we assess based on the NASA-TLX protocol,the workload perception of simple temporal-spatial tasks

Census of HII regions in NGC 6754 derived with MUSE: Constraints on the metal mixing scale

We present a study of the HII regions in the galaxy NGC 6754 from a two pointing mosaic comprising 197,637 individual spectra, using Integral Field Spectrocopy (IFS) recently acquired with the MUSE instrument during its Science Verification program. The data cover the entire galaxy out to ~2 effective radii (re ), sampling its morphological structures with unprecedented spatial resolution for a wide-field IFU. A complete census of the H ii regions limited by the atmospheric seeing conditions was derived, comprising 396 individual ionized sources. This is one of the largest and most complete catalogue of H ii regions with spectroscopic information in a single galaxy. We use this catalogue to derive the radial abundance gradient in this SBb galaxy, finding a negative gradient with a slope consistent with the characteristic value for disk galaxies recently reported. The large number of H ii regions allow us to estimate the typical mixing scale-length (rmix ~0.4 re ), which sets strong constraints on the proposed mechanisms for metal mixing in disk galaxies, like radial movements associated with bars and spiral arms, when comparing with simulations. We found evidence for an azimuthal variation of the oxygen abundance, that may be related with the radial migration. These results illustrate the unique capabilities of MUSE for the study of the enrichment mechanisms in Local Universe galaxies.Comment: 13 pages, 7 Figurs, accepted for publishing in A&

Transcriptional and biochemical changes in mouse liver following exposure to a metal/drug cocktail. Attenuating effect of a selenium-enriched diet

Real-life pollution usually involves simultaneous co-exposure to different chemicals. Metals and drugs are frequently and abundantly released into the environment, where they interact and bioaccumulate. Few studies analyze potential interactions between metals and pharmaceuticals in these mixtures, although their joint effects cannot be inferred from their individual properties. We have previously demonstrated that the mixture (PC) of the metals Cd and Hg, the metalloid As and the pharmaceuticals diclofenac (DCF) and flumequine (FLQ) impairs hepatic proteostasis. To gain a deeper vision of how PC affects mouse liver homeostasis, we evaluated here the effects of PC exposure upon some biochemical and morphometric parameters, and on the transcriptional profiles of selected group of genes. We found that exposure to PC caused oxidative damage that exceeded the antioxidant capacity of cells. The excessive oxidative stress response resulted in an overabundance of reducing equivalents, which hindered the metabolism and transport of metabolites, including cholesterol and bile acids, between organs. These processes have been linked to metabolic and inflammatory disorders, cancer, and neurodegenerative diseases. Therefore, our findings suggest that unintended exposure to mixtures of environmental pollutants may underlie the etiology of many human diseases. Fortunately, we also found that a diet enriched with selenium mitigated the harmful effects of this combination of toxicants

In Silico analysis of protein neoplastic biomarkers for cervix and uterine cancer

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