Production of nanoparticles of copper compounds by anodic dissolution of copper in organic solvents

The anodic behaviour of copper was investigated in ethanol solution containing LiClO₄, LiCl electrolyte and water. The type of electrolyte and the water content influences the mechanism of the anodic process and the formation of anodic products. In LiClO₄ electrolyte the dissolution of copper is related to the oxidation of Cu(I) to Cu(II). In solutions of LiCl the etching of copper begins with the creation of soluble complexes of Cu(I) with chloride ions and solvent molecules. At potentials above 0.4 V the formation of alkoxides was observed in both solutions, characterized by a yellow tint. On the other hand, above 0.8 V (i.e. above the equilibrium potential of alcohol oxidation) copper dissolution is accompanied by the formation of a blue colloidal suspension of Cu (II) copper salt. Anodic etching of copper in solutions containing 3% H₂O at potentials higher than 0.4 V leads to the formation of colloidal suspension of copper oxide nanoparticles.     

Numerical modelling of the electrochemical behaviour of 316L stainless steel based upon static and dynamic experimental microcapillary-based techniques

Microcapillary-based techniques allow the selection and interrogation of single metallurgical sites and are therefore becoming increasingly popular to investigate the electrochemical behaviour of metallic phases and non-metallic heterogeneities in alloys. This study has been carried out to assess the differences between current measurements made using a ‘closed’ microcapillary system (the electrochemical microcell technique) with current measurements derived from a flowing ‘open’ microcapillary droplet cell (the scanning droplet cell). The experimental results were compared with calculations derived from a model system adopting a finite element approach. The corrosion system consists of four parallel electrochemical reactions: three cathodic reactions (the oxygen reduction reaction, the hydrogen evolution reaction and water dissociation) and one anodic reaction (metal dissolution reaction). Comparative experimental results have shown there is a large discrepancy between the magnitudes of the cathodic current obtained by the two techniques. The results of this study allow an assessment of the parameters responsible for the mass transport and distribution of species in the closed and open systems. Critical parameters (for example, microcell crevice geometry, specimen surface-capillary gap distance, etc.) which lead to significant modifications of the curves were then identified using the numerical simulation.     

Long-term effect of norepinephrine on iodide uptake in FRTL-5 cells

The sympathetic nervous system plays a role in the regulation of thyroid function. In FRTL-5 rat thyroid cells, norepinephrine (NE) acutely depresses intracellular I- by increasing I- efflux. The present study was undertaken to determine the effect of NE on iodide transport after a longer time period. NE inhibited the ability of thyrotropin (TSH) to induce iodide uptake by FRTL-5 cells after 48 or 72 hours, but not after 24 hours. The effect of NE was more evident with increasing concentrations of TSH. NE did not modify the rate of I- efflux. Inhibition was associated with a decrease in the Vmax and no change in the Km for iodide influx. To determine if this was a generalized effect of NE on thyroid cell membrane, the uptake of alpha-aminoisobutyric acid (a nonmetabolizable aminoacid) and of 2-deoxyglucose was measured. NE did not inhibit TSH stimulation of the uptake of the two compounds. NE inhibited the action of dibutyryl cAMP (dbcAMP) on iodide uptake in a similar manner to TSH, but did not alter the cyclic adenosine monophosphate (cAMP) levels increased by TSH. The effects of different adrenoreceptor agonists and antagonists demonstrated that norepinephrine acts through an alpha1-adrenergic receptor.     

Local electrochemical studies after heat treatment of stainless steel: Role of induced metallurgical and surface modifications on pitting triggering

The morphology, the chemical composition, and the pitting corrosion resistance of a resulfurized stainless steel heated at 1000 °C for 2 hours were investigated at the microscale using ex-situ (field-emission-scanning electron microscope/electron dispersion spectrometer (FE-SEM/EDS) and secondary ion mass spectroscopy (SIMS)) and in-situ (electrochemical microcell technique and in-situ atomic force microscope (AFM) techniques. Although microcracks, which may have a deleterious effect, exist, the formation of a compound (Cr,Mn)₂(O,S)₃ instead of MnS is responsible for the better pitting corrosion resistance of sites containing an inclusion. Local electrochemical measurements indicate that no pitting was detected on these sites below 800 mV/SCE (saturated calomel electrode), whereas stable pitting was observed at around 350 mV/SCE before heating. Micropores were detected on the highly oxidized grains in which the ionic activity was found to be more marked than on the remaining surface (determined using in-situ AFM). Local electrochemical measurements revealed that the presence of such defects reduces significantly the corrosion resistance of the metallic alloy in NaCl-based media.     

Corrosion Resistance of MgZn Alloy Covered by Chitosan-Based Coatings

Chitosan coatings are deposited on the surface of Mg20Zn magnesium alloy by means of the spin coating technique. Their structure was investigated using Fourier Transform Infrared Spectroscopy (FTIR) an X-ray photoelectron spectroscopy (XPS). The surface morphology of the magnesium alloy substrate and chitosan coatings was determined using Scanning Electron Microscope (FE-SEM) analysis. Corrosion tests (linear sweep voltamperometry and chronoamperometry) were performed on uncoated and coated magnesium alloy in the Hank’s solution. In both cases, the hydrogen evolution method was used to calculate the corrosion rate after 7-days immersion in the Hank’s solution at 37 °C. It was found that the corrosion rate is 3.2 mm/year and 1.2 mm/year for uncoated and coated substrates, respectively. High corrosion resistance of Mg20Zn alloy covered by multilayer coating (CaP coating + chitosan water glass) is caused by formation of CaSiO₃ and Ca₃(PO₄)₂ compounds on its surface.     

Quantitative renal scintigraphic determination of effective renal plasma flow in dogs with normal and abnormal renal function, using 99mTc-mercaptoacetyltriglycine

Effective renal plasma flow (ERPF) was evaluated, using the measurement of p-aminohippurate clearance (CLPAH) and quantitative renal scintigraphy (QRS) with 99mTc-mercaptoacetyltriglycine (99mTc-MAG3). The CLPAH and QRS determinations were made in 6 dogs: 2 determinations for each dog before, and 1 determination after induction of renal failure by administration of amphotericin B. Least-squares regression analysis was used to derive an equation to estimate ERPF from QRS data. The results indicated that QRS, using 99mTc-MAG3, correlated reasonably well (r = 0.82, P < 0.001) with ERPF determined from the CLPAH value. The right kidney contributed 53.3% of global ERPF (P = 0.002). Hepatobiliary excretion of 99mTc-MAG3 was variable within each dog. There was not a consistent pattern with respect to time or renal function. All dogs had nausea or emesis, or both, after IV administration of 99mTc-MAG3. The QRS method with 99mTc-MAG3 provides an adequate means to estimate ERPF in healthy dogs and dogs with renal failure.     

Influence of the dissolution of MnS inclusions under free corrosion and potentiostatic conditions on the composition of passive films and the electrochemical behaviour of stainless steels

The influence of the dissolution of MnS inclusions at the OCP value and 400 mV versus SCE on the chemical composition of passive films and the electrochemical behaviour of resulfurized austenitic stainless steel was studied in 1 M NaClO₄, pH 3, solution using SIMS, XPS, electrochemical impedance spectroscopy and the electrochemical microcell technique. The electrochemical dissolution (at 400 mV versus SCE) of inclusions occurred uniformly along the interface and this process was almost complete after 25 min immersion. A small amount of sulfur was detected on the matrix that exhibited a wide passive range. By contrast, the dissolution process under free corrosion was not uniform along the interface and numerous inclusions were partly dissolved. Grains close to the completely dissolved inclusions showed an active behaviour. This was connected with the adsorption of a large number of sulfur on the surface. In the two cases, the presence of sulfur species on the surface was also found to enhance the kinetics of cathodic reactions.     

ROUGH SET REDUCTION OF ATTRIBUTES AND THEIR DOMAINS FOR NEURAL NETWORKS

This paper presents an empirical study of the use of the rough set approach to reduction of data for a neural network classifying objects described by quantitative and qualitative attributes. Two kinds of reduction are considered: reduction of the set of attributes and reduction of the domains of attributes. Computational tests were performed with five data sets having different character, for original and two reduced representations of data. The learning time acceleration due to data reduction is up to 4.72 times. The resulting increase of misclassification error does not exceed 11.06%. These promising results let us claim that the rough set approach is a useful tool for preprocessing of data for neural networks.     

Locally geometric semantic crossover: a study on the roles of semantics and homology in recombination operators

This study presents an extensive account of Locally Geometric Semantic Crossover (LGX), a semantically-aware recombination operator for genetic programming (GP). LGX is designed to exploit the semantic properties of programs and subprograms, in particular the geometry of semantic space that results from distance-based fitness functions used predominantly in GP. When applied to a pair of parents, LGX picks in them at random a structurally common (homologous) locus, calculates the semantics of subprograms located at that locus, finds a procedure that is semantically medial with respect to these subprograms, and replaces them with that procedure. The library of procedures is prepared prior to the evolutionary run and indexed by a multidimensional structure (kd-tree) allowing for efficient search. The paper presents the rationale for LGX design and an extensive computational experiment concerning performance, computational cost, impact on program size, and capability of generalization. LGX is compared with six other operators, including conventional tree-swapping crossover, semantic-aware operators proposed in previous studies, and control methods designed to verify the importance of homology and geometry of the semantic space. The overall conclusion is that LGX, thanks to combination of the semantically medial operation with homology, improves the efficiency of evolutionary search, lowers the variance of performance, and tends to be more resistant to overfitting.     

Evolving strategy for a probabilistic game of imperfect information using genetic programming

We provide the complete record of methodology that let us evolve BrilliAnt, the winner of the Ant Wars contest. Ant Wars contestants are virtual ants collecting food on a grid board in the presence of a competing ant. BrilliAnt has been evolved through a competitive one-population coevolution using genetic programming and fitnessless selection. In this paper, we detail the evolutionary setup that lead to BrilliAnt’s emergence, assess its direct and indirect human-competitiveness, and describe the behavioral patterns observed in its strategy.

---