O objetivo deste trabalho é a extração de Au, Ag, Cu e Zn a partir de dois tipos de lodos galvânicos utilizando um processo híbrido de sulfatação seletiva e lixiviação com tiossulfato de sódio e amônio. Nos experimentos realizados, o lodo galvânico foi misturado com um agente promotor de sulfato (enxofre, sulfato de ferro ou pirita) e foi tratado por processos pirometalúrgicos a temperaturas até 750◦C. Nesta fase, este agente sulfatante é oxidado térmicamente, transformando a atmosfera do forno e os óxidos metálicos em sulfatos solúveis em água. Depois disso, os sulfatos foram tratados por lixiviação com água para a recuperação de Ag, Cu, Ni e Zn. Como o ouro não forma sulfatos nesta reação, foi realizada uma segunda fase de lixiviação utilizando tiossulfato de sódio e de amônio, reagentes eficazes e menos prejudiciais ao ambiente do que o cianeto. Diferentes parâmetros foram analisados como qual agente promotor de sulfatação apresentou a maior recuperação de metais em solução, a proporção ótima lodo galvânico/ agente sulfatação, a temperatura de forno, o tempo de aquecimento no forno e o tempo de lixiviação. Além disso, uma comparação da recuperação de ouro com cianeto e tiossulfato de sódio e de amônio foi realizada. A configuração que demonstrou a melhor recuperação de metal em solução tinha uma proporção de 1: 0,4 de lodo galvânico/enxofre, uma temperatura de forno de 550◦C, um tempo de aquecimento de 90 minutos e um tempo de lixiviação em água de 15 minutos. Usando estes parâmetros, as taxas de recuperação de 75% de prata, 68% de cobre, 52% de Ni e 67% de Zn foram obtidas. A lixiviação de tiossulfato de sódio resultou em uma recuperação de 78% do Au, próximos aos valores obtidos utilizando cianeto. / The purpose of this work is the selective extraction of Au, Ag, Cu and Zn from two types of galvanic sludge using a mixed process of sulfate roasting and sodium thiosulfate and ammonium thiosulfate leaching. In the experiments, the sludge was mixed with a sulfate promoter (sulfur, iron sulfate or pyrite) and treated by pyrometallurgical processes at temperatures up to 750◦C. At this stage, this agent is thermally oxidized, turning the furnace atmosphere and the metallic oxides into water-soluble sulfates. Afterward, the sulfates can be treated by leaching with water for recovery of Ag, Cu, Ni and Zn. The gold does not form sulfates in this reaction and was recovered through a second leaching stage using sodium and ammonium thiosulfate, an effective reagent and less harmful to the environment than cyanide. Different parameters as the sulfate promoter that achieves the highest recovery of metals, the proportion of galvanic sludge to sulfating agent, the temperature, the heating time in the oven and the leaching time were evaluated. Additionally, a comparison of gold recovery using cyanide versus sodium and ammonium thiosulfate was performed. The configuration that showed the best metal recovery included a 1:0.4 ratio of sludge to sulfur, an oven temperature of 550◦C, a roasting time of 90 minutes and a water leaching time of 15 minutes. Using these parameters, recovery rates of 75 % of the silver, 68% of the copper, 52% of Ni and 67% of the Zn were obtained. The sodium thiosulfate leaching resulted in a recovery of 78% of the Au, close to the values obtained using cyanide.

La présente étude porte sur le problème de l'entreposage à long terme des déchets nucléaires. En France, il est prévu que les déchets radioactifs à haute activité et vie longue soient confinés dans un surconteneur en acier au carbone, puis stockés à une profondeur d'environ 450 m dans une formation argileuse (argilite). En raison de l'intense radioactivité, une température proche de 90°C est attendue à la surface de l'acier. Dans un premier temps, il a été nécessaire de synthétiser, par polarisation anodique à courant imposé, des couches de produits de corrosion susceptibles de se former en conditions de stockage. Les électrodes d’acier S235 ont été recouvertes d’une couche d’argilite broyée et immergées en solutions carbonatées. La synthèse a d’abord été effectuée à 25°C afin de déterminer les paramètres influant sur la nature des produits de corrosion, puis à 80°C de façon à se rapprocher des conditions réelles. Les composés obtenus dépendent de la concentration en NaHCO3, de la densité de courant imposée et du temps de polarisation. A 80°C, la magnétite Fe3O4 et la sidérite FeCO3 sont les principaux produits formés. La rouille verte carbonatée FeII4FeIII2(OH)12CO3.2H2O et la chukanovite Fe2(OH)2CO3 n'ont pu être détectées que localement dans certaines conditions. Des sulfures de fer, notamment la mackinawite, se forment en début d’expérience pour des densités de courants anodiques modérées. Dans la deuxième partie de l’étude, nous avons étudié l’influence des espèces sulfures sur un système constitué par l’acier et une couche de produits de corrosion modèle. Les modifications de cette couche préalablement formée, induites par les espèces sulfures, ont été plus particulièrement étudiées. Enfin, la dernière partie de notre travail de recherche a porté sur l’étude des couplages galvaniques pouvant s’établir entre deux zones de la surface de l’acier recouvertes de produits de corrosion différents. Nous avons notamment étudié les couplages impliquant la magnétite Fe3O4, principal composé conducteur susceptible de se former en conditions de stockage. / The present study relates to the problem of the long-term interim storage of nuclear wastes. In France, it is envisaged that high-level radioactive wastes will be confined in a glass matrix, stored in a stainless steel canister, itself placed in a carbon steel overpack. The wastes will then be stored at a depth of ~450 m in a deep geological disposal, drilled in a very stiff (indurated) clay (argillite) formation. A temperature as high as 90°C is expected at the steel surface because of the intense radioactivity. Anodic polarization at applied current density was used to synthetize corrosion product layers likely to be formed in storage conditions. The S235 steel electrodes were covered by a layer of argillite and dipped in carbonated solutions. The synthesis was first achieved at 25°C to determine the parameters controlling the nature of the corrosion products and then at 80°C to be closer to the real conditions. The nature of the obtained compounds proved to be dependent on NaHCO3 concentration, on current density and on polarization time. At 80°C, magnetite Fe3O4 and siderite FeCO3 were the main identified compounds. Carbonate green rust FeII4FeIII2(OH)12CO3.2H2O and chukanovite Fe2(OH)2CO3 were detected locally in some experiments. Iron sulfides, mainly mackinwaite, also formed at the beginning of the experiments with a moderate current density. In the second part of the study, the influence of sulfide species on the steel / model corrosion products layer system was investigated. The modifications of the layers previously formed by anodic polarization induced by sulfide species were more particularly studied. Finally, the last part of our research was focused on the effects of a galvanic coupling that could appear between two areas of the steel coated by different corrosion products. In particular, galvanic couplings involving magnetite Fe3O4, the main conductive compound likely to form under storage conditions, were studied.

Abstract Patients with idiopathic Parkinson's disease (PD) may suffer from autonomic nervous system dysfunction even in the early phase of the disease. We assessed the autonomic cardiovascular and sudomotor regulation in de novo PD patients with and without medication. We also measured the dopamine (DAT) and serotonin transporter (SERT) uptake in the PD patients using 2β-carboxymethoxy-3β-(4-iodophenyl)tropane (β-CIT) SPECT and studied the clinical correlates of the uptake. Sixty PD patients were included in the study and randomised to receive levodopa, bromocriptine or selegiline (n=20 in each) as their treatment. Thirty patients were examined with β-CIT SPECT. The results of the patients were compared with those of healthy controls and within the subgroups at different time points. Cardiovascular autonomic regulation was assessed using standard cardiovascular reflex tests at baseline, after six months' medication and following a 6-week washout period. The heart rate (HR) and blood pressure (BP) regulation was impaired in PD patients at baseline, and PD medications modified the responses further. Bromocriptine and selegiline, in contrast to levodopa, increased the orthostatic BP fall and suppressed the BP response to isometric exercise. The long-term cardiovascular autonomic function was evaluated from ambulatory ECG recordings by analysis of traditional spectral and non-spectral components of HR fluctuation together with two-dimensional vector analysis and power-law relationship analysis of the HR dynamics. All spectral measures and the slope of the power-law relationship demonstrated impaired tonic cardiovascular regulation in the PD patients. Sympathetic sudomotor activity was evaluated using the sympathetic skin response (SSR). The major finding was suppression of the SSR amplitudes with an inverse correlation to clinical disability, whereas PD medication seemed to have only minor effects. The changes in amplitude and repetitiveness of the SSRs with normal adaptation suggest deficits at several levels of the SSR reflex arc. DAT uptake, assessed by β-CIT SPECT, was diminished in the striatum and especially the putamen of the PD patients, and correlated with the results of the cardiovascular reflex tests and ambulatory ECG recordings. Simultaneous measurement of SERT binding demonstrated decreased SERT availability in the thalamic and frontal areas. The results demonstrate disturbances of the reflectory and tonic cardiovascular autonomic regulation caused by PD itself. PD medications further modify the reflectory responses. The degenerative process in PD also involves the sympathetic sudomotor pathway. β-CIT SPECT provides a useful method for simultaneous assessment of DAT and SERT binding, demonstrating the deficit of serotonin metabolism in PD.

This research aims to monitor workers’ physiological reactions in virtual construction scenario. With the objective of leveraging affective sensing technology in construction scenario, experiments with Galvanic Skin Response (GSR) was conducted in a 3D simulation developed based on a real construction site. The GSR results obtained from sensor were analyzed in order (i) to assess the feasibility of using virtual environment to generate real emotions, (ii) to examine the relation between questionnaires used to ask people about their experience and their physiological responses and (iii) to identify the factors that affect people’s emotional reactions in virtual environment. Subjects of the experimental group exhibited incoherent responses, as expected in experiments with human subjects. Based on the various reasons for this incoherence obtained from questionnaire part of the experiment, the potential in research for developing training methods with respect to workers’ physiological response capability was identified.

Magnesium (Mg) is the lightest of all structural metals and has tremendous potential for applications in the lightweight industry. However, the corrosion of Mg is a significant barrier towards its wider use. Despite years of research, the fundamental understanding of Mg corrosion still remains short. The enhanced hydrogen evolution reaction (HER) with anodic polarization, the modeling of galvanic corrosion and the impact of hydrogen bubbles for galvanically coupled Mg are important aspects of Mg corrosion that need to be understood before any mitigation measures can be taken. The results presented in this work provide a key step in that direction. In the first part of the project, we explored how the kinetics of reactions involved in the Mg corrosion was influenced by surface changes. A significant difference in Tafel kinetics between a polished Mg surface and a pre-corroded Mg surface was seen. It was also shown that when the concurrent Mg dissolution was accounted for during the cathodic polarization, the absolute value of Tafel slope decreased by a factor of ~2. The enhanced HER on Mg during high anodic dissolution rate was also investigated. The Mg samples were first pre-corroded at different rates until entire Mg surface was corroded. It was found that the surface roughness decreased with an increased rate of corrosion and therefore did not have any influence in enhancing HER at the Mg surface during the anodic dissolution. In order to observe the catalytic effect of anodic dissolution, the potential was immediately dropped to a constant cathodic potential following the pre-corrosion and the current was observed with the time. A peak current, proportional to the prior dissolution rate, was observed. At longer times, the current decayed and converged to similar values irrespective of the prior pre-corrosion rate providing a strong evidence that the enhanced HER is caused due to the catalytic effect provided by the anodic dissolution. Our results provide new mechanistic insights into the current understanding of enhanced HER.In the second part of the project, a numerical simulation was developed to predict the galvanic corrosion rates of Mg coupled to steel. The simulation showed that the kinetics of HER estimated from the cathodic polarization (where significant anodic dissolution rates were absent) underpredicted the experimental HER rates by two orders of magnitude signifying the catalytic effect of anodic dissolution. The simulation allowed us to independently fit the HER kinetics. The simulation also predicted the galvanic current densities and the corrosion potential within 14% error which is a significant improvement of model precision reported previously for galvanic corrosion of Mg corrosion. For the first time, the influence of HER during galvanic corrosion of Mg was reported. Despite substantial hydrogen evolution observed during the experiment, the influence of hydrogen evolution was found to be only 8-9%.

The master thesis deals with design of a switched DC power supply with output parameters of 30 V 60 A. The power supply uses the connection of two single switch forward converters with opposite phase. The topology was chosen based on a comparison of specific schematics in the first part. The body of the thesis is covered in chapter which deals with design and analysis of power circuits of the converter. The chapter describes detailed design of pulse transformers, dimensioning of semiconductors and cooling system of the converter. For lower power losses, the system of synchronous rectifying is chosen at the output of the circuit. The regulation of the output is based on cascade structure with a superior voltage and dependent current loop. Appropriate over current protection is provided by sensing the output current and using current transformers for primary current measure.

Background Measuring pain in infants is important but challenging for researchers and health care professionals. The measurement of skin conductance (SC) is considered as a measure of stress and a surrogate indicator of pain. Purpose This dissertation provides insight on the validity of SC for pain measurement in infants and consists of two studies: 1) a scoping review synthesizing the methods and findings of previous studies on validating or using SC for measuring pain in infants; 2) a primary study evaluating the validity of SC for measuring pain in mechanically ventilated infants. Methods Arksey and O’Malley’s framework informed the methods of the scoping review. Nine electronic databases were searched. Data were analyzed and presented descriptively. The primary study used a prospective cross-sectional observational design. Eligible infants were those up to 12 months of age, hospitalized in intensive care units, who were mechanically ventilated, and required painful and non-painful procedures. Results Scoping review: Twenty-eight studies with 1061 infants were included, including 23 cross-sectional observation studies and five interventional studies. The validity evidence of SC was tested in relation to referent pain measures (13 variables), stimuli (13 variables), age (2 variables) and other contextual variables (11 variables). Fifteen studies evaluated the validity evidence in relation to phase of painful procedure, and SC increased significantly during painful procedures in most studies (n=14/15). However, inconsistent findings on other validity evidence and wide variation in methods existed across studies. Primary study: SC showed good validity in relation to the category of procedure, the phase of procedure and the referent pain measures in critically ill mechanically ventilated infants. The findings from diagnostic test accuracy showed that SC had good capacity of detecting moderate to severe pain. However, the values of SC need to be used with caution, due to the imperfect correlations with the referent pain measures and imperfect positive predictive value. Conclusions SC is a promising approach to measuring pain in critically ill infants. Further research testing the validity of SC in relation to pain treatments and advancing the technology of measuring and analyzing SC is needed before it can be recommended for clinical use.

Between 1994 and 2003 spatial disorientation resulted in at least 202 aircraft accidents, 184 of them resulting in fatalities. Galvanic Vestibular Stimulation (GVS) provides a cost effective and safe way to simulate spatial disorientation and potentially test pilot’s vestibular system prior to aircraft operation. This experiment investigates the use of GVS as an indicator of motion sensitivity and explores the effects of GVS on flight simulation performance. Bilateral bipolar rectangular pulse electrical stimulations were given to subjects via skin-mounted electrodes placed over each mastoid process to stimulate the vestibular system with roll and yaw sensations. Two studies were conducted in this work: one on motion sensitivity and one to examine the effects of GVS during flight simulator use. The motion sensitivity test consisted of an alternating GVS sequence to simulate rolling back and forth. The sequence did generate motion sickness in two out of 12 subjects. Results show no correlation to motion history scores calculated from Kennedy’s Motion Sickness Questionnaire (MSQ). The flight simulator test coupled automatically generated congruent, conflicting, and sham orientation sensations to the roll angles of the aircraft. The stimulations used in this test did not indicate any effect on the simulator flight performance of the subjects. Feedback from subjects during this test raised concern over the delay between left- and right-side stimuli. Further testing to reduce the surface skin sensation showed that a ramp or increasing exponential waveform not only reduced the sensation of current entering the body but significantly increased the orientation sensations resulting from the stimulation. Increasing the orientation response and decreasing the sensation of current breaking the surface of the skin provides a much more desired stimulation for each of the tests in this experiment and any other future tests related to GVS.

The Galvanic Plating Technology is used by many branches of modern industry. Sizeable amounts of waste water are an integral part of plating technologies. It contains a versatile spectrum of chemical substances hazardous to the environment. This work focuses on monitoring the level and nature of waste water pollution resulting in primary production. Several indicators were selected to appreciate the quality of the effluent, which were defined according to the procedures. The possibility of quality monitoring process based on values of pollution was discussed after evaluating the results.

Aligned arrays of nanostructures has recently attracted great interest because of their unique properties and potential use in a broad range of technological applications. The nanostructures can be employed when it is essential to create large surface on a small area in electronic device as sensor technology or energetics e.g. solar panels. One of the simplest and low-cost methods of fabricating nanostructures is template-assisted electrochemical deposition. This method also enables good control over the nanostructure dimensions and can be used to deposit a wide range of materials. The proposed method consists of two steps. At first, a non-conductive nanoporous template has to be created and then nanostructures are formed by electrodeposition into the template which is coated with a metal on one of its sides or placed on a metal surface.