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Nafion 112/polyaniline (Na/PANi) composite membranes were synthesized by chemical polymerization of aniline on the perfluorinated structure for use in direct methanol fuel cells as a solid electrolyte. The morphology and physicochemical properties of the composite membranes were analyzed by scanning electron microscopy (SEM), attenuation Fourier reflection infrared spectroscopy (FTIR-ATR), and X-ray photoelectron spectroscopy (XPS). The electrochemical properties of the membranes were investigated by scanning electrochemical microscopy (SECM), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). The results show that PANi-modified Nafion during 1 and 24 h decrease the methanol crossover by 78% and 89% and increase the proton conductivity by 17% and 2.6% respectively.

Due to their distinctive chemical, electronic, and environmental properties, polypyrrole is used as a blocking barrier for methanol leakage in direct methanol fuel cells. Here, a straightforward deposition method of polypyrrole deposition on Nafion has been achieved by chemical polymerization in an aqueous medium. The chemical polymerization has been carried out during 1 h and 24 h; thus, the effect of the polypyrrole coating has been studied toward the leakage of methanol by cyclic voltammetry. It was found that the diffusion of methanol has been reduced for at least to three decades in comparison to commercial Nafion. The effect of the polypyrrole (PPy) coating on transport properties such as water uptake, ion exchange capacity, and proton conductivity has been investigated. Scanning electrochemical microscopy (SECM) has been used to investigate quantitatively the membrane proton conductivity. A potentiometric tungsten microelectrode, positioned above the membrane, was used to monitor directly the diffusion of H+. The chemical and morphological characterization of PPy coating has been characterized by Fourier transform infrared FTIR–ATR spectroscopy, X-ray photoelectron (XPS), scanning electron microscope (SEM), and atomic force microscopy (AFM).

This work aims to elaborate PPy-flax composite via chemical in-situ polymerization of pyrrole on flax fiber in aqueous medium. The flax-PPy gas sensor was examined for trimethylamine gases. It was found that the electrical resistance of PPy coating increases in the presence of organic vapors while it decreases in clean air. The results of this study show the high efficiency of flax-PPy sensor toward toxic vapors. The influence of input parameters such as gas concentration has also been investigated. The synthesized sensor was characterized by different techniques such as X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM).

A novel cellulose-based bio-battery made of electrospun fibers activated by biological fluids has been developed. This work reports a new concept for a fully organic bio-battery that takes advantage of the high surface to volume ratio achieved by an electrospun matrix composed of sub-micrometric fibers that acts simultaneously as the separator and the support of the electrodes. Polymer composites of polypyrrole (PPy) and polyaniline (PANI) with cellulose acetate (CA) electrospun matrix were produced by in situ chemical oxidation of pyrrole and aniline on the CA fibers. The structure (CA/PPy|CA|CA/PANI) generated a power density of 1.7 mW g−1 in the presence of simulated biological fluids, which is a new and significant contribution to the domain of medical batteries and fully organic devices for biomedical applications.

Graphene and graphene-based materials have shown great promise in many technological applications, but their large-scale production and processing by simple and cost-effective means still constitute significant issues in the path of their widespread implementation. Here, we investigate a straightforward method for the preparation of a ready-to-use and low oxygen content graphene material that is based on electrochemical (anodic) delamination of graphite in aqueous medium with sodium halides as the electrolyte. Contrary to previous conflicting reports on the ability of halide anions to act as efficient exfoliating electrolytes in electrochemical graphene exfoliation, we show that proper choice of both graphite electrode (e.g., graphite foil) and sodium halide concentration readily leads to the generation of large quantities of single-/few-layer graphene nanosheets possessing a degree of oxidation (O/C ratio down to ∼0.06) lower than that typical of anodically exfoliated graphenes obtained with commonly used electrolytes. The halide anions are thought to play a role in mitigating the oxidation of the graphene lattice during exfoliation, which is also discussed and rationalized. The as-exfoliated graphene materials exhibited a three-dimensional morphology that was suitable for their practical use without the need to resort to any kind of postproduction processing. When tested as dye adsorbents, they outperformed many previously reported graphene-based materials (e.g., they adsorbed ∼920 mg g

The sorption capacity of bone char was tested on the removal of copper, nickel and cadmium ions, from aqueous solutions. The Freundlich and Langmuir models were applied to the adsorption isotherms. The equilibrium data fitted well with the Langmuir model and the maximum loading capacities showed the following affinity order: Cu2+ (1.093 mmol g–1 at pH i 3, and 0.884 mmol g–1 at pH i 4) > Cd2+ (0.760 mmol g–1 at pH i 3, and 0.690 mmol g–1 at pH i 4) > Ni2+ (0.453 mmol g–1 at pH i 3, and 0.225 mmol g–1 at pH i 4). The kinetic data follow a diffusion model in the film and inside particles. A sorption mechanism based on ion exchange, attack by protons of the carbonate and hydroxide positions in the apatite lattice, and also on the adsorption of protons on the basic active sites of carbon, is proposed to explain the heavy metals removal and the pH decreasing in solution.

Polyaniline (PANi) films electrosynthesized on the stainless steel electrodes were used as an adsorbent to remove two polycarboxy-benzoic acids, trimellitic (Tri) and pyromellitic (Pyro) acids, from aqueous solutions. The electropolymerization of aniline has been investigated in different aqueous media such as H2SO4, HClO4 and HNO3. The film electrosynthesized in H2SO4 medium revealed high adsorption capacities as 80.85 and 88.65% for Tri and Pyro acids, respectively. The influence of different parameters such as monomer concentration, supporting electrolyte concentration, and electrodeposition time on the adsorptive properties of PANi films was evaluated and systematically optimized.

The electrochemical behavior of polypyrrole (PPy)-coated carbon steel (CS) was investigated in aqueous NaCl solution by scanning electrochemical microscopy. Oxygen concentration and pH were monitored by placing Pt and Sb microelectrodes, respectively, over the CS sample surfaces while soaking them in corrosion media. The PPy layer provided anodic protection, as well as a physical barrier, against the corrosive effect. The ratio of these properties was dependent on the thickness of the coating. Electrosynthesis of PPy/CS was achieved in an aqueous solution of sodium tartrate and pyrrole using cyclic voltammetric and galvanostatic techniques. The coatings were characterized by X-ray photoelectron spectroscopy and scanning electron microscopy. The doping rate calculated from XPS spectra was estimated at 15 %. The corrosion protective extent of the coating was tested in 3 % NaCl solution using three different techniques: linear polarization, open circuit potential, and electrochemical impedance spectroscopy. PPy offered significant protection against corrosion, with the coating resistance decreasing as immersion time increased.

Polypyrrole films were deposited electrochemically on carbon steel from sodium saccharinate aqueous medium using cyclic voltammetry, potentiostatic and galvanostatic techniques. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and normalized tape test show that the polypyrrole coating is homogeneous and adherent to carbon steel surface with globular structure. The adherence rate depends closely on the applied current densities. The corrosion protection performance of the coating was investigated by potentiodynamic polarization technique, open circuit potential over time, and electrochemical impedance spectroscopy (EIS) in 3% sodium chloride solution.

The modification of the chemical structure of the cotton fibers was carried out in basic medium using succinic anhydride in pyridine. The anhydride monomer was added to cotton fiber, previously activated by sodium hydroxide or potassium permanganate solution, by graft polymerization that was followed by using the parameters, i.e., monomer concentration, pyridine concentration, modification time and temperature. The graft yield was characterized by back-titration and FTIR analysis. The adsorption capacity of the graft cotton was performed on the removing of methylene blue from aqueous solutions. Adsorption isotherms were studied by the Freundlich, Langmuir and Temkin models. The kinetics data follow a second order model and the cellulose support grafted showed an adsorption capacity of 710 mg g−1, which means an improvement of about 40% in comparison with the cellulose support raw material.

A corrosion spreading throughout the 304 stainless steel tubing of a water system to supply various buildings was observed, and also leaks were detected in welding zones. The same place is also crossed by a gas distribution network, with a helium pipe 316 of stainless steel that required periodic repairs more or less every two years, due to the presence of leaks. The tests showed that both types of stainless steel have suffered localized corrosion induced by hypochlorite ion, in a mechanism of dry/wet, and that the welding procedure performed on the 304 stainless steel is unacceptable. Some immediate procedures were undertaken to keep systems running, but recommendations were given for a final resolution of the problems.

Two CeO2/carbon nanotube composites were prepared in both basic and neutral medium thus using different deposition procedures of the cerium oxide. The modification of the synthesis conditions varied the hydrolysis rate of the cerium oxide precursor, leading to materials with different morphology, texture and surface chemistry, significantly changing their electrochemical performance. The different mechanisms of charge storage occurring on the surface of the materials were thoroughly studied to investigate the origin of the observed changes in the electrochemical properties. To that end, a combination of sweep wave voltammetry and deconvolution analysis in acid (1 M H2SO4), basic (1 M NaOH) and neutral (1 M Na2SO4) electrolytes was conducted. The faradaic activity of the composite prepared by slow hydrolysis (containing well-dispersed and small ceria particles) is enhanced as compared with the composite prepared by fast hydrolysis, which originates bulky particles.

The authors present a Case Study conducted in a Portuguese military organization, to answer the following research questions: (1) what are the most relevant dimensions and categories of information security controls applied in military organizations? (2) What are the main scenarios of information security incidents that are expected to occur? (3) What is the decision process used for planning and selection information security controls? This study reveals that: (1) information security within the military organization is built on the basis of physical and human attack vectors, and targeting the infrastructure that supports the flow of information in the organization; (2) the information security controls applied in the military organization are included in ISO/IEC 27001; (3) planning and selection of applied information security controls are made by decision makers and information security specialists. It appears that specialists impose their planning options essentially seeking to select and retrieve past successful information security cases.

A linear correlation between free energy and enthalpy for crystalline and soluble oxocompounds based in the Sverjensky–Molling equation is used to calculate the Gibbs free energies of formation of MnWO4 (−1172.48 ± 12.76 kJ mol−1), H2WO4 (−1006.91 ± 10.36 kJ mol−1), and Na2WO4 (−1455.39 ± 12.81 kJ mol−1). Using these data with the known thermodynamic data, the equilibrium constants for reactions of leaching of scheelite and wolframite in acidic and basic media were determined. The results show that the acid route based in relatively cheap inorganic acids is desirable for scheelite digestion, despite the diffusion problems concerned with tungstic acid developed on the solid particles. Meanwhile, wolframite may be operated under favorable thermodynamics conditions by alkaline and acid processes.

The metallization of acrylonitrile butadiene styrene (ABS) has been achieved using a new direct plating process that consisted of a previous treatment by polypyrrole (PPy) to transform the plastic conductor followed by direct copper electroplating. The deposition of PPy on ABS samples is reached chemically in a solution of pyrrole and iron(III) chloride as oxidant. The PPy synthesized is adherent to the plastic surfaces. Adherent copper layers with different thicknesses have been obtained on PPy/ABS at different electrolysis time. Energy dispersive X-ray spectroscopy (EDS) analysis revealed that copper is deposited on PPy/ABS surface. SEM analysis shows that increasing the electrolysis time increases the copper coating thickness.

Tinplate steel cans were used to store contact glue for shoes. A few months after its storage, the glue displayed a change in colour to a darker brown. The visual inspection of the interior of the cans showed the presence of corrosion of steel, which was evidenced by the typical colour of the iron oxides on the sheet. SEM/EDS and FTIR tests confirmed that the anomaly was due to the following factors: (a) a bad tin coating, small thickness and lack of homogeneity; (b) a degradation of glue, hydrolysis of chloroprene, which led to its acidification. Some recommendations are made to overcome similar situations within the same use of these packages looking at the specifications of tinplate.

Nickel electroplating of acrylonitrile butadiene styrene (ABS) plastic has been achieved successfully without any chromium or palladium pretreatment. Once the ABS is coated with polypyrrole (PPy), the sample may be electroplated. The process is fast, economic and involves three stages. Firstly, chemical deposition of PPy on ABS, secondly, copper deposition and finally nickel electroplating. A homogenous and adherent PPy has been synthesized chemically on ABS plate by using pyrrole as monomer and iron (III) chloride as oxidant. Copper and nickel were deposited galvanostatically from industrial plating baths. The metallic coatings were homogeneous and the adherence was estimated at 100%. The thickness of copper and nickel depend on the electrolysis time. As the current density increases, the Cu and Ni thickness raises. This result was confirmed from SEM characterization and RX map. The Ni coating is characterized by a globular structure with globules of different sizes. Energy dispersive X-ray spectroscopy (EDS) analysis shows the presence of Ni with some amount of carbon and oxygen due to the nickel oxides and contaminant from the bath solution.

The electrodeposition of polypyrrole and polyaniline has been performed in aqueous solutions of sodium saccharinate and sulphuric acid, respectively. The coatings were obtained by voltamperometric and galvanostatic methods. The corrosion behaviour of polypyrrole and polyaniline coated stainless steel (SS) in sulphuric acid medium was investigated by linear polarisation, open circuit potential and electrochemical impedance spectroscopy. The polyaniline coatings doped with sulphate anions (SO42−) showed more resistance to protect SS to corrosion than the polypyrrole coatings doped with saccharinate anions (C7H4NO3S−).

This work relates a study on a medieval coin found during archaeological works carried out at the site of Senhora do Castelo in Urros (Torre de Moncorvo, Portugal). The artefact has been identified as a coin of D. Afonso IX of Leon (1155–1188). The substratum showed composition typical of bullion, Cu-Ag (30–33%) with minor elements (1% Pb + 0.2% Sn + 0.4% Zn). The corrosion products developed on the coin during the archaeological burial was studied by means of optical microscopy (OM), scanning electron microscopy combined with energy dispersive spectrometry (SEM-EDS), energy dispersive X-ray fluorescence (EDXRF), and X-ray diffraction (XRD). The results show the presence of cuprite, atacamite, chalcocite, native silver, silver oxide and silver sulphide on the outer layers of the coin, which allows deducing the importance of the environment in the corrosion phenomena.

A commercial sheet of paper based on natural cellulose fibers acting as permeable membrane with thin film metal cathode (Cu) and anode (Al) layers in each face was used to produce paper batteries that could be interconnected in series and rechargeable using water as electrolyte. Their electrical characteristics and the set of electrochemical reactions that support the experimental behavior observed are described in this paper. A series of integrated batteries able to supply a voltage of about 3 V and a current ranging from 0.7 μA to 25 μA in cells with sizes of 1.2 cm × 3.0 cm for a relative humidity in the range of 50–65% were produced in a single sheet of paper, and successfully applied to control the ON/OFF gate state of paper transistors.

Cathodic protection, often taught in curricular units, such as corrosion and materials science, is an important subject in the study of chemical engineering. The implementation of lab setups and experimental activities in this field, are core to promoting understanding of the underlying concepts and to developing &ldquo, hands-on&rdquo, skills fundamental to the success of future process engineers. This paper reports the influence of different variables on the electrical potential and current behaviors of an educational cathodic protection system operated with a single drainage point. The system comprised a steel bar cathode connected to a zinc sacrificial anode, both placed in aqueous medium. The study variables were the anode area, the cathode diameter, the NaCl electrolyte concentration and the anode placement. Each variable showed a specific influence on the attenuation curves, allowing us to conclude that: (1) increasing the sacrificial anode area, or decreasing the resistivity of the medium, promotes more electronegative potentials on the structure and higher currents, (2) increasing the cathode diameter decreases the protection capacity, (3) positioning the anode in the middle of the cathode lengthwise gives rise to a more balanced potential distribution, and (4), the attenuation curves, both for potential and current, can be successfully predicted using equations based on Morgan and Uhlig&rsquo, s work. High correlations were obtained between the experimental and modeling data for all the studied variables.

The influence of pH on pyrrole electropolymerization on iron surfaces in malate aqueous medium was analyzed using different electrochemical techniques. The sodium sulfate solution was used as reference. Homogeneous and adherent PPy films were obtained at pH between 4 and 7 in 0.2 M malic and 0.5 M pyrrole solution by potentiostatic mode, while the PPy coatings obtained from sulfate aqueous solutions in the same range of pH are non-adherents significantly. SEM analysis showed that PPy structure depends closely on the electrochemical conditions. FT-IR analysis confirms that PPy coatings have the same structure as those obtained on Pt electrodes.

The electrochemical behaviour of dimethylamine borane and borohydride on platinum electrodes was investigated by cyclic voltammetry and polarization curves in discharges processes. Several overlapping peaks appear in the domain of hydrogen oxidation, i.e., in the potential range of −1.25 V to −0.50 V versus Ag/AgCl, mainly with the borohydride. This behaviour is associated with the hydrolysis of BH 4 − or (CH 3 ) 2 NHBH 3 . As a consequence of secondary reactions the borohydride and dimethylamine borane oxidation in 3 M NaOH solution shows, respectively, a four- to six-electron process and a four- to five-electron process in direct fuel cells. The direct oxidation of the borohydride exhibits a peak at about −0.07 V versus Ag/AgCl, while the dimethylamine borane peak is at about −0.03 V versus Ag/AgCl. For the 0.04 M concentration the borohydride displays a power density of 31 W m −2 which is 16% higher than that of the dimethylamine borane.

The electrochemical behaviour of sodium borohydride on a platinum electrode in the absence and presence of thiourea (TU) was investigated by cyclic voltammetry. In the absence of thiourea, several overlapping peaks associated with the hydrolysis of BH4− appear in the domain of hydrogen oxidation, i.e., in the potential range of −1.25 to −0.50 V versus Ag/AgCl. As a consequence of secondary reactions, the borohydride oxidation in 3 M NaOH solution shows a four to six-electron process, according to its concentration, in direct fuel cells. A conveyable TU/NaBH4 concentration ratio of 0.6 inhibits the delivery of hydrogen simultaneously with catalytic hydrolysis of BH4−. Thus, the coulombic efficiency in direct fuel cell discharge was increased showing an about eight-electron process for the oxidation of BH4−.

The electrochemical behaviour of stainless steel electrode in 0.1 M sodium saccharinate solution in the absence and the presence of the monomer were investigated using several electrochemical techniques such as cyclic voltammetry, galvanostatic and potentiostatic. The XPS analysis was used to study the elementary composition of the obtained polymer and to estimate the doping level of the PPy obtained under this electrolytic conditions. Moreover, the characterization of the coating was achieved by SEM, IR and Raman. In this context, samples of PPy in oxidized and reduced state synthesized galvanostatically on stainless steel grid were used to investigate the behaviour of the polymer toward acetone vapor.

The recovery of tungsten from alkaline leach solutions has been studied examining the effect of temperature, pH, Ca/WO3 molar ratio and nature of the precipitated calcium tungstate. The precipitation kinetics of calcium tungstate, upon the addition of aqueous sodium tungstate to calcium solutions, was followed by potentiometric measurements using a calcium ion-selective electrode. Two models, a crystal growth model and a second-order reaction opposed by zero-order reaction, have been used to test the experimental data. Both models show that the apparent activation energy of CaWO4 precipitation falls in the range 58 to 67 kJ mol− 1. The kinetic data shows that the maximum recovery of precipitated calcium tungstate occurs at pH ≥ 8.5 with a 10% excess of CaCl2 at 50 °C over a period of 20 min using sodium tungstate solutions of 100 g L− 1 and 150 g L− 1 WO3.

The electrochemical synthesis of polypyrrole (PPy) on copper and brass has been successfully achieved in sodium saccharinate and pyrrole aqueous medium. The synthesized coating under several electrochemical techniques such as cyclic voltammetry, galvanostatic and potentiostatic is homogeneous and adherent. PPy has been characterized by SEM, XPS, IR and Raman spectroscopy and its quality has been confirmed. The doping level obtained from N 1s XPS signal of the oxidized PPy depends on the electrochemical technique used to produce the film. The corrosion performance of PPy/copper and PPy/brass has been evaluated in 3% NaCl and 0.1 M HCl using linear polarization and electrochemical impedance spectroscopy. The results show that PPy coating electrodeposited from sodium saccharinate exhibits significant corrosion protection properties.

The electrosynthesis of polypyrrole (PPy) has been achieved on aluminium in aqueous medium of malic acid by means of cyclic voltammetry, potentiostatic and galvanostatic techniques. Scanning electron microscopy (SEM) and X-ray microanalysis by dispersion energy spectroscopy (EDS) applying on surfaces show that the PPy coating is developed from the metal surface through the cracks of the initial Al 2 O 3 layer. Moreover, the results reveal that the homogeneity of the film achieved increases with the time of electropolymerization. A mechanism involving the participation of the supporting electrolyte and the pyrrole (Py) in distinct active sites was proposed based on the linear sweep voltammetry. It is observed for all the applied electrochemical techniques that the pyrrole concentration has to be higher than 0.1 M to allow the polypyrrole electrodeposition in acid medium. Scanning electron microscopy, secondary electrons (SE) and backscattering electrons (BE), shows that the PPy coating obtained in galvanostatic and potentiostatic modes starts with small islands at weak applied potentials or current densities. The corrosion results in 3% NaCl medium show that the PPy coating decreases the corrosion behaviour of the aluminium. The bilayer Al 2 O 3 /PPy shows a capacitor with future applications.

The differential aeration cells are responsible in practice for multiple corrosion forms. The established tension gradients between the cathodic and anodic areas are quite reduced, and consequently both electrodes stay submitted also to corrosion phenomena due to local-action cells. By analysing the theoretical current–potential curves it is shown that differential aeration cells are not responsible for an increase of the electrode corrosion in the oxygen-starved electrolyte in the absence of secondary effects. Differential aeration cells developed on normal carbon steel were investigated in H2CO3/HCO3−/CO32− solutions of different pH values. The results from polarization data and immersion corrosion tests of coupling indicated have shown the following: (1) the electrode in the aerated zone, for each one of the chosen pH, tends to attain the same potential of the electrode in the deaerated zone; (2) an alkalization of the electrolyte in the aerated and deaerated zones for initial pH 5 and 7.5 in the system; (3) the current density that cross the macrocell is little, of the same order for all pH, and does not justify the observed corrosion rate in both electrodes; (4) there is a polarity inversion of the electrodes for the pH 5 and 7.5; (4) the observed corrosion rate in each one of the tested solutions was practically the same for the aerated and deaerated electrodes. An explanation for this behaviour is given.

The electrosynthesis of polypyrrole (PPy) has been achieved on aluminium in aqueous medium of tartaric acid by means of cyclic voltammetry, potentiostatic and galvanostatic techniques. Scanning electron microscopy (SEM) and X-ray microanalysis by energy spectroscopy dispersion (EDS) applying on surfaces show that the PPy coating is developed from the metal surface through the cracks of the initial Al2O3 layer. A mechanism involving the participation of the supporting electrolyte and the pyrrole (Py) in distinct active sites was proposed based on the linear sweep voltammetry. It is observed for all applied electrochemical techniques that the pyrrole concentration has to be higher than 0.1 M to allow the polypyrrole electrodeposition in acid medium. Scanning electron microscopy, secondary electrons (SE) and backscattering electrons (BE), shows that the PPy coating obtained in galvanostatic and potentiostatic modes starts with small islands at weak applied potentials or current densities. Moreover, EDS reveals a good homogeneity and compactness of the film achieved in galvanostatic method. The corrosion results in 3% NaCl medium show that the PPy coating decreases the corrosion behaviour of the aluminium. The bilayer Al2O3/PPy shows a capacitor with future applications.

In this work, the relation between oxidant/monomer ratio and the electrical conductivity of polypyrrole was studied using different ratios. We achieved a maximum value for electrical conductivity of 7.5 S/cm for a ratio of 2:1. We also developed a chemical dip-coating process to produce the cathode layer in tantalum capacitors. We obtained capacitances of about 80 µF after 8 cycles using the sequence Monomer/Oxidant.

The electrochemical synthesis of polypyrrole on iron has been fruitfully achieved in aqueous medium of sodium saccharinate and pyrrole. The obtained coating under these conditions has been reached with cyclic voltammetry and chronomethods. The applied current density has a great effect on the thickness of PPy electrodeposited on iron electrodes. The characterization techniques show a good homogeneity of the PPy coating. The corrosion behaviour of PPy/Fe was investigated in sodium chloride by linear polarization, electrochemical impedance spectroscopy, and weight loss. The results show that PPy coating electrodeposited could provide a good protection against corrosion.

The electrodeposition of polypyrrole (PPy) on oxidizable metals such as aluminum and iron has been achieved in aqueous medium of saccharin and pyrrole. Scanning electron microscopy and X-ray photoelectron spectroscopy analysis reveal a good homogeneity of the obtained PPy film. The electrochemical synthesis of PPy coating has been achieved successfully under potentiodynamic, galvanostatic and potentiostatic techniques. The corrosion experiments performed in HCl show that the PPy coating increases the corrosion potential and decreases the corrosion current density.

A single-step electropolymerization of pyrrole on zinc-coated steel electrodes in aqueous medium was investigated under several techniques (potentiodynamic, galvanostatic and potentiostatic modes) by using carboxylate salts, such as the citrate, the succinate, the oxalate, the malate and the tartrate. Adherent and homogeneous PPy coatings were obtained only with tartrate counter-ions. The corrosion behaviour of zinc-coated steel electrodes electrochemical modified by PPy films were estimated by open circuit potential and DC polarization in NaCl, HCl and H2SO4 aggressive solutions. The obtained results show that the PPy coatings increase the corrosion potential and reduce the corrosion current. The salt spray test results show that the PPy coating prepared under ultrasonic waves is more resistant than those obtained in normal conditions.

The electrosynthesis of polypyrrole (PPy) on copper and brass (Cu–Zn alloy) electrodes was performed by anodic oxidation of pyrrole in a sodium tartrate (C4H4Na2O6 0.2 M) aqueous solution. The tartrate counter-ions slow the dissolution of the working electrode by leading to formation of a passivation layer on its surface, and pyrrole electropolymerization takes place. Strongly adherent and homogeneous polypyrrole films were electrodeposited on Cu and Cu–Zn alloy electrodes using different electrochemical techniques, such as potentiodynamic, galvanostatic and potentiostatic modes. The current densities of electropolymerization on brass are generally greater than those observed on copper. The corrosion behaviour of copper-coated electrodes, electrochemically modified by PPy films, was estimated by DC polarization and weight loss at different current densities in 0.1 M HCl solution. The synthesized polypyrrole films were characterised by several microscopic and spectroscopic techniques such as scanning electron microscopy, X-ray photo electron spectroscopy, Fourier transform infrared and Raman analysis. Galvanostatically deposited PPy films are shown to be an alternative to common black-nickel or black-chromium as a decorative top-coating.

The kinetics of the leaching reaction of synthetic scheelite with hydrochloric acid was studied to determine the effect of pH and temperature in the formation of tungstic acid. Conversion data obtained from leaching in a temperature range of 28–100 °C and pH between 1.5 and 3.0 are interpreted in terms of the predominating tungsten species present in the leaching liquors. The results show that it is possible to digest the synthetic scheelite in the acidic hydrochloric medium without the formation of tungstic acid by monitoring and controlling the pH, and controlling the temperature in the domain of metatungstates. In this case, the experimental results match with the shrinking core model, and show that the solids leaching is kinetically under both chemical and mass transfer control.

Obtaining of tungstic oxide from wolframite concentrates involves the production of synthetic scheelite and/or tungstic acid as intermediate products. The present work studies the influence of different factors affecting the particle size of these compounds and also investigates the correlation between its granulometry and the final grain size of WO 3 . The research included as main goals (i) the study of the effect on the synthetic scheelite grain size of the following parameters—concentration and amount of calcium chloride; concentration of tungstate solution and type of mixing and stirring, (ii) the study of the correlation between granulometric sizes of synthetic scheelite and final tungstic oxide granulometric sizes, (iii) the study of the effect of temperature, type of agitation, concentration and amount of hydrochloric acid on the recovery and particle size of tungstic oxide. Conditions to produce WO 3 powders with tailor-made micrometric grain size from 10 to 0.5 μm are presented.

Electropolymerization of pyrrole on zinc–lead–silver (Zn–Pb–Ag) alloys was carried out in acetonitrile, nitrobenzene and propylene carbonate (PC) organic media in the presence of para -toluene sulfonate counter ions. Adherent and homogeneous PPy films have been obtained on zinc alloy electrodes (65% Zn, 10% Pb and 25% Ag) prealably treated with aqueous sodium sulfide solution. Among the electrochemical techniques used in these experiments, the galvanostatic mode was proved to be better adapted to perform the electrosynthesis of polypyrrole using low applied current densities. The PPy coatings have been characterized by different microscopic and spectroscopic techniques. Scanning electron microscopy (SEM) showed that PC (DN=15.1) is the most suitable solvent for elaborating high-quality and thick PPy films. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) analysis proved that the obtained coatings have the same structure properties as those electrodeposited on noble Pt plates.

A single-step electropolymerization of pyrrole (Py) on iron and steel surfaces has been performed in aqueous medium in the presence of malate (C 4 H 4 O 5 2− ) as supporting electrolyte. The malate counter-ion slows down the iron dissolution by leading to the formation of a passivation layer on the working electrode surface, and the Py electropolymerization starts on. The polypyrrole (PPy) films electrosynthesized under different electrochemical techniques are uniform and adherent. The polymer coatings performed galvanostatically have a cauliflower-like structure and are thicker than those obtained by potentiodynamic mode. The adherence of PPy layers to the iron electrodes was estimated at 100% according to the standard sellotape test. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) analysis showed that the obtained coatings have the same structure and morphological properties as those electrodeposited on Pt electrodes.

Homogeneous and strongly adherent polypyrrole (PPy) films were electrochemically synthesized on iron electrodes in sodium tartrate (Na2C4O6H4 0.2 M) aqueous solution. This one step pyrrole electropolymerization process has been successfully achieved under different electrochemical techniques, such as potentiodynamic, galvanostatic and potentiostatic modes. During the first stage of the electrochemical process the tartrate counterion slows down the iron dissolution by leading to the formation of a passivation layer on the working electrode surface, and the pyrrole electropolymerization takes place. The electrosynthesized polymer deposit has been characterized by several microscopic and spectroscopic techniques. Any iron traces have been detected by X-ray photoelectron spectroscopy (XPS) on the outer side of the PPy films, which confirms the compactness and the homogeneity of the polymeric coating. Scanning electronic microscopy (SEM) imaging showed uniform and compact PPy coatings with cauliflower-like structure. Infra-red (IR) and Raman spectroscopies proved that the obtained PPy films have the same vibrational properties as those electrodeposited on noble Pt plates.

The electrodeposition of polypyrrole on zinc electrodes has been performed by anodic oxidation of pyrrole in acetonitrile, nitrobenzene and propylene carbonate media in the presence of para-toluene sulfonate counter-ions. When the zinc electrode has preferably undergone a chemical treatment by aqueous sodium sulfide solution, homogeneous and adherent PPy films are obtained. While, no PPy film grows (in the case of C6H5NO2 and PC) or a non-homogeneous and poorly adherent PPy–zinc oxide composite forms (in the case of CH3CN) when the zinc surface is simply polished. Among the electrochemical techniques used in these experiments, the galvanostatic mode was proved to be better adapted to perform the electropolymerization of pyrrole on the pretreated zinc electrodes using low applied current densities. The polypyrrole films synthesized by this technique has been characterized by several microscopic and spectroscopic techniques. In particular, SEM, XPS, FT-IR and Raman analyses showed that the obtained coatings have the same structure and morphological properties as those electrodeposited on Pt electrodes.

The aim of this paper is to present results concerning the morphology, structure, mechanical and electrical characteristics of the new proposed Cu–Sn metallurgical alloy, which may be used in electronic joins. By proper choice of process temperature and pressure, Cu coated surfaces are soldered using Sn as pre-form. The main results achieved indicate that the formation of Cu3Sn phase begins at a temperature of about 473 K and that the Sn thickness (dSn) needed is slightly above 7 μm. Due to join wettability, higher temperatures (between 523 and 573 K) and dSn above 35 μm are required to form joins within the specifications of the electronic industry.

Results are presented on the electrical characteristics of power diodes soldered using new lead-free techniques based on Cu–Sn–Cu joints. Special emphasis is put on the role of the thickness of the Cu films electrodeposited on the electrical performances of the power diodes joined and to study the electrical stability of the joints formed, under extreme aggressive conditions.

The aim of this paper is to present results on a new soldering process based on the low-temperature solidification of intermetallic phases from the system Cu–Sn–Cu which can be employed to form a heat-resistant die-attach as well as signal and power electric contacts. Because of the total transformation into intermetallic phase, the working temperature of the bond formed is several hundred degrees Celsius higher than the process temperature (around 250°C). This process leads to a homologous temperature T/Tm of about 0.3 compared to 0.7 in the case of soft SnAg solder alloy. Therefore a better reliability of the proposed bonding process is achievable. Results of the match of the predicted volume fraction of the intermetallic forms and the experimentally measured contact volume would be also discussed, for contacts formed in power diodes.

The electrodeposition of polypyrrole (PPy) on aluminium electrodes has been achieved in phosphoric acid medium by using potentiodynamic, potentiostatic and galvanostatic techniques. The corrosion behavior of polypyrrole on aluminium in sodium chloride medium has been investigated by open circuit potential and electrochemical impedance spectroscopy. A mechanism to explain the beneficial effect of PPy-doping dihydrogenophosphate ion in the passivation of aluminium is proposed. A electrodeposição do polipirrole (PPy) sobre alumínio em soluções de ácido fosfórico foi obtida através de técnicas potenciodinâmicas, potenciostáticas e galvanostáticas. O comportamento do alumínio revestido com polipirrole em meio de cloreto de sódio foi investigado através do potencial de circuito aberto e espectroscopia de impedância electroquímica. É proposto um mecanismo para explicar o efeito benéfico do íon dihidrogenofosfato na passivação do alumínio.

A criminalidade é algo que afeta as nossas vidas, bem como a forma de viver em sociedade. O conhecimento da realidade sócio-criminal é de extrema importância para o desenvolvimento das sociedades. As temáticas da criminalidade e segurança têm vindo, nos últimos tempos, a ser alvo de enorme pressão pela comunicação social, pelo governo e pela comunidade civil. Desta forma, urge a necessidade de encontrar novas leituras de informação, a nível regional e local, sobre áreas de ocorrências ou incidentes associados à criminalidade e incivilidade - as áreas de intervenção das forças de segurança - de forma a melhor se compreender as suas causas. Só assim se poderá agir, numa ótica da prevenção e combate ao fenómeno. A diversidade espacial do nosso território é conhecida e estudada desde há muito, contudo, raramente se pensa e articula este conhecimento com os fenómenos criminais. A criminalidade está diretamente articulada com a geografia e com os fenómenos que ocorrem num determinado território. Segundo as teorias da criminologia, tratar apenas dados reportados é insuficiente para efetuar uma análise correta da criminalidade e criar políticas de segurança e prevenção do fenómeno criminal. Com o desenvolvimento de aplicações de Sistemas de Informação Geográfica (SIG) desde 1990, os analistas criminais em todo o mundo têm usado e ponderado os princípios da Geografia de forma a perceber e criar mecanismos de prevenção e segurança da população. Vários especialistas afirmam que o mapeamento da criminalidade tem um impacto no entendimento do crime e dos problemas sociais. Desta forma, a geografia aplicada tem um papel preponderante neste tipo de fenómeno, no sentido em que se conhecermos uma determinada área e a forma como essa afeta as áreas de proximidade, podemos perceber como e onde se localiza determinado fenómeno ou acontecimento. Isto é a Geografia da criminalidade, uma importante ferramenta de apoio à decisão em questões de segurança pública e prevenção do crime. Esta apresentação tem assim como objetivos principais: (i) perceber a dimensão e espacialização das forças de segurança, (ii) reconhecer áreas problemáticas e vulneráveis da cidade de Lisboa, (iii) propor soluções de segurança e prevenção da criminalidade com o reforço de unidades e instalações policiais.

The present work proposes the development of a bio-battery composed by an ultrathin monolithic structure of an electrospun cellulose acetate membrane, over which was deposited metallic thin film electrodes by thermal evaporation on both surfaces. The electrochemical characterization of the bio-batteries was performed under simulated body fluids like sweat and blood plasma [salt solution – 0.9% (w/w) NaCl]. Reversible electrochemical reactions were detected through the cellulose acetate structure. Thus, a stable electrochemical behavior was achieved for a bio-battery with silver and aluminum thin films as electrodes. This device exhibits the ability to supply a power density higher than 3 μW cm −2 . Finally, a bio-battery prototype was tested on a sweated skin, demonstrating the potential of applicability of this bio-device as a micropower source.

The principle objective of this article is to present a literature review for the methods used in the security of information at the level of organizations. Some of the principle problems are identified and a first group of relevant dimensions is presented for an efficient management of information security. The study is based on the literature review made, using some of the more relevant certified articles of this theme, in international reports and in the principle norms of management of information security. From the readings that were done, we identified some of the methods oriented for risk management, norms of certification and good practice of security of information. Some of the norms are oriented for the certification of the product or system and others oriented to the processes of the business. There are also studies with the proposal of Frameworks that suggest the integration of different approaches with the foundation of norms focused on technologies, in processes and taking into consideration the organizational and human environment of the organizations. In our perspective, the biggest contribute to the security of information is the development of a method of security of information for an organization in a conflicting environment. This should make available the security of information, against the possible dimensions of attack that the threats could exploit, through the vulnerability of the organizational actives. This method should support the new concepts of “Network centric warfare”, “Information superiority” and “Information warfare” especially developed in this last decade, where information is seen simultaneously as a weapon and as a target.