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Estudo da influência dos aditivos manitol, EDTA e NTA no processo de eletrodeposição de zinco sobre aço 1010 e na morfologia dos eletrodepósitos
(Universidade Federal de São Carlos, 2009-08-21) Carvalho, Marcos Fernandes de; Carlos, Ivani Aparecida; https://lattes.cnpq.br/1666217445807782; https://lattes.cnpq.br/0922916090536806
In this paper the effects of adding mannitol, EDTA or NTA to an alkaline deposition bath on the electrodeposition of zinc on to AISI 1010 steel substrate were evaluated. Voltammetric curves of 1010 steel in deposition bath with mannitol or EDTA additives showed similar profiles. However, for NTA it was different. These experiments indicated that the current density (j) of zinc electrodeposition increased due to hydrogen evolution reaction (HER) from H2O reduction occurring in parallel to this process. The voltammograms of 1010 steel substrate in deposition bath with and without mannitol or EDTA showed two regions c0 and c1, due to iron oxide reduction/HER/initial zinc bulk deposition and secondary zinc bulk deposition, respectively. These regions were called b0 and b1, as NTA was present in deposition bath. In the region c1, for deposition bath with and without mannitol or EDTA, the j was similar, suggesting that the area of zinc electrodeposit did not differ significantly, unlike the plating bath with NTA (region b1). From cyclic voltammograms with lowerlimit potential, can be seen that the initial zinc bulk deposition occurred at - 1.45 V in cathodic sweep to deposition bath with and without mannitol or EDTA and this potential was shifted 100 mV in the positive direction (- 1.35 V) in the presence of NTA. When the sweep was reversed at - 1.60 V all the deposition bath showed, in the anodic sweep, a zinc dissolution peak. The current efficiency (e) was always lower than 100%, due to HER occurring in parallel to the zinc electrodeposition. It was verified that in the presence of NTA additive, higher values of e (55.8%) was obtained and also, zinc electrodeposits were thicker (2.65 μm) for charge density (qd) 10.0 C cm-2. For qd = 2.0 C cm-2, irrespective the additives, the values of e and thickness () were comparable. The morphological studies of zinc electrodeposits showed that all the additives work as a brightener, since refining of the zinc grains. The EDX analysis showed that for qd = 2.0 C cm-2 the oxygen incorporation did not occur for 0.20 mol L- 1NTA or 0.20 mol L-1EDTA, but was below detection limit for the 0.20 mol L-1 mannitol. For qd = 10.0 C cm-2, it can be seen that as plating bath containing 0.20 mol L-1 EDTA the oxygen incorporation was hindered in the zinc electrodeposits.
Compósitos de Polipirrol e Li1,05Mn2O4 : preparação por dip coating ou casting e caracterização eletroquímica
(Universidade Federal de São Carlos, 2009-08-21) Brocenschi, Ricardo Francisco; Biaggio, Sonia Regina; https://lattes.cnpq.br/0418215244233120; https://lattes.cnpq.br/4530780432056175
Films of polypyrrole/Li1.05Mn2O4 composites were prepared by chemical synthesis over a carbon-fiber substrate, using the dipcoating and casting techniques, aiming at improving the performance of these materials as cathodes in secondary lithium or lithium-ion batteries. For this the following were investigated: i) electrochemical behavior of both materials (polymer and oxide) over the carbon-fiber surface; ii) electrochemical characteristics and stability of the composites obtained by the different methods; iii) best electrolyte to work at high potentials (> 4 V vs. Li/Li+); iv) electronic conduction of the composites; v) morphology of both components of the composites; vi) behavior of the composites as cathodes of lithium-ion batteries. From the obtained results it could be concluded that neither preparation technique led to films with a good electrical contact between the spinel crystals and the carbon fibers, which is necessary for them to show a high performance for charge storage. For the materials prepared by dip coating, the use of factorial design effectively helped in obtaining a higher specific-capacity value for polypyrrole (118 mA h g-1), but that was not the case for the polypyrrole/Li1.05Mn2O4 composite (only 20 mA h g-1). On the other hand, for the films prepared by casting, the electronic conduction of the spinel was increased due to the polypyrrole and carbon black mixture, while the most appropriate electrolyte for the electrochemical characterizations was 1 mol L-1 LiClO4 in EC:DMC 1:1 (V/V). However, only the predominantly capacitive behavior of the carbon fiber was observed in the charge/discharge tests. Finally, the charge/discharge tests of the polypyrrol/Li1.05Mn2O4 composite compacted over platinum yielded values of ~70 mA h g-1 for the first cycle and a better stability than that presented by the pure spinel.
Os trabalhadores da indústria de software: flexíveis e precários?
(Universidade Federal de São Carlos, 2009-08-21) Oliveira, Daniela Ribeiro de; Lima, Jacob Carlos; https://lattes.cnpq.br/9244132532446607; https://lattes.cnpq.br/3340719766336945
Considering the current labor crisis and the many forms that work have assumed precarious, informal, temporary or part-time -, our intention here is studying a set of workers whose rose as result of the development of information technology within the context of flexible capitalism: workers of software industry. The knowledge of information language is what defines the qualification and possibilities of these kind of workers within labor market, but in Brazilian case these kind of workers usually are submitted to atypical work contracts like work by project, part-time job, temporary job, outsourcing job and even kind of jobs protected by labor Brazilian laws. We semi-structured-interviews with eighteen workers whose continued employments were distributed of this way: six workers under Brazilian laws standard, five trainees, one free-lance, one Legal Entity Person , three entrepreneur partners and two public employees one public server and other a scholar. The research was done in São Carlos and Araraquara, cities located in the central region of São Paulo State. We to understand the workers point of view about the different types of labor contracts, to outline a profile of qualification these workers and their work trajectory and figure out the labor processes that they are submitted. In addition to interviews, we analyzed the content of specialized websites about Information Technology (IT) and software development, as well as available magazines and newspapers online and printed.
Obtenção e condutividade elétrica de vitrocerâmica Li1+xAlxTi2-x(PO4)3 com diferentes microestruturas
(Universidade Federal de São Carlos, 2009-08-21) Semanate, José Luis Narváez; Rodrigues, Ana Candida Martins; https://lattes.cnpq.br/4499231813051400; https://lattes.cnpq.br/9824558997496023
Technological advances in portable devices imply not only the development of devices but also the need to enhance their power sources. For instance, cellular phones with high technology incorporating Bluetooth, Infrared, Digital Camera, Games, GPS, Internet Browsing, etc., need high performance rechargeable batteries. Lithium ion-conducting glass-ceramics with NASICONtype structure, based on the Li1+xMxM'2-x(PO4)3 system, where M = Al, Cr, Fe, Ga and M' = Ge, Ti, Hf, are considered good candidates as solid electrolytes in lithium ion batteries due to their chemical stability, easy fabrication and high ionic conductivity. In this work, the Li1+xAlxTi2-x(PO4)3 glass composition was synthesized by the traditional method known as Splat Cooling. Glass-ceramics with the same composition as the precursor glass but with different microstructures were obtained by controlled crystallization, using single and double heat treatments. The parent glass was characterized by chemical and thermal analysis and the latter enabled tailoring of the crystallization heat treatments. X-ray diffraction (XRD) results indicated that the resulting glassceramics exhibit the desired NASICON-type structure as primary phase, as well as the segregation of insulating phases, i.e., AlPO4 and/or TiO2, which do not affect the electrical properties. An examination of the microstructure by scanning electron microscopy (SEM) and measurements of electrical conductivity by impedance spectroscopy (IS), combined with the XRD analysis, indicated that the electrical conductivity of single heat-treated samples increases with the heat treatment temperature and hence with the increase in crystallinity. Samples synthesized by double heat treatment showed increasing electrical conductivity with decreasing nucleation treatment time and consequently with increasing average grain size.
Efeito de estímulos vibratórios aplicados na região plantar sobre o equilíbrio corporal de idosas
(Universidade Federal de São Carlos, 2009-08-21) Wanderley, Fábio da Silva; Rebelatto, José Rubens; https://lattes.cnpq.br/1684247449456330; https://lattes.cnpq.br/3866913143880127
Objective: To determine the effect of vibration stimuli with 100 Hz frequency, applied to the plantar region, the body balance in women aged less than 60 years. Method: We selected 30 women aged less than 60 years with lack of static balance measured by the test support Unipodal with eyes open. The participants were randomly divided into an experimental group and a control group. All subjects were evaluated by four additional tests: the test Unipodal support with eyes closed, the Time Up and Go test, the Functional Reach test adapted, and Static Posturography evaluated using the force platform. A study was conducted blind, and the evaluators did not know to which group subjects were. The subjects in the experimental group received vibration therapy applied directly in the plant with 100 Hz frequency and oscillation of 2 mm. We performed 24 sessions of vibration stimuli, applied by the same physiotherapist. We analyzed the changes of the average number of individuals by two-way ANOVA with Tukey test as post-hoc to the data showing normal, and for not presenting normality test was used to Friedman. The comparison of the averages of the groups, experimental and control, was done using the one-way ANOVA for data presented normal and Kruskal-Wallis test for those who did not show normality. Results: We found significant differences between experimental and control groups in the third assessment of the Functional Reach test adapted in the speed of oscillation of the center of anterior-posterior pressure with the eyes open and closed and the area of Oscillation of the center of pressure with eyes closed. In examining the three evaluations of the intervention group was found to improve body balance in the Functional Reach test adapted in the speed of oscillation of the center of anterior-posterior pressure with the eyes open and closed and the area of Oscillation of the center of pressure with eyes closed. In the control group there was no statistically significant difference in any of the tests. Conclusion: The vibration stimuli applied to the plantar region, with 100 Hz frequency, showed beneficial effects on body balance in women over 60 years, being more effective in postural control of anteriorposterior axis and during the deprivation of vision.
Subsídios ao extrativismo de briófitas no município de Cananéia, SP
(Universidade Federal de São Carlos, 2009-08-21) Rancura, Sheila Aparecida de Oliveira; Nordi, Nivaldo; https://lattes.cnpq.br/8168865557947289; https://lattes.cnpq.br/7489765544523782
The management of non-timber forest products is an important alternative to forests maintenance. Nevertheless, the demand for some species at commercial scale may result in negative impacts to the local biodiversity. The bryophytes, particularly species of Sphagnum and Syrrhopodon genera, are among the vegetal resources exploited in restinga areas of Cananéia, in the south coast of São Paulo State, Brazil. After the organization of the harvesters in an association, the extraction is now legally carried out in licensed areas. The harvesting of bryophytes by the local population aims to supply the ornamental plants market, but there is a lack of studies to estimate the impact of the exploration providing information to the proper management of these resources. In order to provide subsidies for extraction and management of bryophytes Sphagnum and Syrrhopodon, this study raised information about the abundance and distribution of the explored bryophytes as well as the havesting practiced in Cananéia. To cover the different aspects involved in the harvesting of bryophytes, this study used Plant Ecology, Human Ecology and Ethnoecology approaches. Information concerning to the harvesters population and the harvesting activity were obtained through informal conversations, interviews and guided tours. Geoprocessing tools were used to characterize the bryophytes exploitation areas. The percentage ground cover by bryophytes was estimated applying the line-transect method and to evaluate the regeneration of Sphagnum plots were established and effected two harvests simulating traditional harvesting. The results indicated that explored bryophytes occur predominantly in Brejo de Restinga and Floresta Baixa de Restinga areas. Under similar conditions to those found in the experiment which simulated the traditional harvesting, the report demonstrated that six and seven months after harvest, Sphagnum presented height and yield like to the initial condition. In this sense, the harvesting, when done under the traditional way, tends to minimize the negative impacts of harvesting on the regeneration of bryophytes. Therefore, the relations determined in the commercialization process define the pressure upon exploited species and induces the harvesters to modify the traditional harvesting, resulting in an overexploitation of some places and a collect of very small bryophytes. Such actions contribute to a lower yield of the collect and may compromise the natural regeneration of some regions. The definition of management rules coupled to the bryophytes market rules built collectively constitute an essential point to established a less predatory harvesting.