A New Method for the Improvement of Data

Introduction – The use of the average analytical signal for the construction of curves by the least squares method (LSM) over the standard addition method (SAM) is widespread. It would be advantageous, however, to fi nd a way to avoid intermediary averages, which are known to be the cause of signifi cant increases in standard deviations (SD). Objective – To develop a protocol that uses all gathered data to create curves by LSM over SAM. To use Excel® for the estimation of y = mx + b and R2 rather than using LSM equations for the SD of m, x and b. Methodology – The level of lead (II) in the bark (cork) of Quercus suber Linnaeus was determined using diff erential pulse anodic stripping voltammetry (DPASV). Three current samples were taken for each of the four standard additions. These signals were combined for adjustment by LSM. The results were compared with those obtained after averaging the current for each addition, and the expression of uncertainty in the measurements determined. Results – The new method shows an expanded uncertainty of ± 0.3321 μg/g (nearly 1.42%). The diff erence between the results obtained by the new and the old method is 0.01 μg/g (23.41 and 23.40 μg/g). The limit of detection changed approximately from 4.8 to 4 μg/g and the relative SD approximately from 9 to 6%. Conclusion – The absence of intermediary averages in curves improved the determination of lead (II) in cork by DPASV. Estimation of SD only with LSM equations produced results that were signifi cantly worse. The changes are large enough to transform an apparently internally non-validated procedure (repeatability for precision) into an internally validated procedure

Electroanalysis of Heavy Metals in the Cork of Quercus Suber

This will enable Pb(II) determination optimisation, regarding environmental aspects of the perpetuation of Quercus suber Montado (similar to Forest). It will also allow a more profound toxicological quality control of corks (barks). These two last referred aspects are very related ones, once accepted that the more advanced could the certification of the quality patterns of corks (barks) be, more will be the sustainability of Quercus suber ecosystem. Which we believe can be done, amongst other vectors, by studying such an important environmental issue as heavy metals. It is shown that Pb(II) quantification in the cork (bark) of Quercus suber tree (Cork Oak) is possible, using Differential Pulse Anodic Stripping Voltammetry (DPASV). The samples digestion was made in a mixture of H2O2 and HNO3 1:8, in a closed recipient at approximately 90 ºC. The measures were made in NaCl 0.1 M, using a Hanging Mercury Drop Electrode, a Glassy-Carbon Rod Counter Electrode, and an Ag/AgCl/KCl 3M reference electrode, after a 180 s deposition step. The results have shown the determination of a coherent stripping potential of -0.405 V (SD=0.0005 V), and a fine linear adjustment after the standard addition method (R2 = 0.997). They have also revealed the interest of further studies. The need to test other electroanalysis requisites was understood, and imposed by the proof of the complex nature of the matrix

CoopDynSim : a 3D robotics simulator

This paper presents CoopDynSim, a multi-robot 3D simulator. The main motivations for the development of a new simulation software lie in the need to emulate specific, custom made sensors, combined with the desire to smoothly transfer controller code from simulation to real implementation. The latter is achieved through the use of the same middleware layer already implemented in the real platforms. The high modularity of the solution allows the user to easily add new components or design new platforms. By having independent simulation threads for each robot, distributed control algorithms can easily be tested, abetted by a socket based connection, granting the possibility for an asynchronous, over the network, controller architecture. The ability to run simulations in real or simulated time, as well as a play back option, represent valuable features of the software. The simulator has been used in several projects, with different platforms and distinct control applications, proving it as a heterogeneous and flexible solution. Furthermore, its usage as a teaching tool in a robotics’ summer school as well as in an introductory robotics class in our university, upholds its simplicity and user-friendliness.Fundação para a Ciência e a Tecnologia (FCT) - ref. SFRH/BD/38885/200

Competitive biosorption of ortho-cresol, phenol, chlorophenol and chromium(VI) from aqueous solution by a bacterial biofilm supported on granular activated carbon

A biofilm of Arthrobacter viscosus supported on granular activated carbon was used to remove chromium and organic compounds (chlorophenol, phenol and o-cresol) from aqueous solutions. The compounds were studied as single solutes and in different combinations between them and Cr(VI). Optimum Cr(VI) adsorption was observed at a phenol concentration of 100 mg/l and at an initial concentration of the metal of 60 mg/l. The maximum values of biosorption of organic compounds were 9.94 mg/g for phenol, 9.70 mg/g for chlorophenol and 13.99 mg/g for o-cresol. In terms of removal percentage, after 15 h of experiment, the affinity order was as follows: phenol > chlorophenol > o-cresol > chromium(VI).Fundação para a Ciência e Tecnologia (FCT

THE IMPORTANCE OF THE CORK (BARK) OF QUERCUS SUBER IN THE

The recent absence of Lead element as catalyst in internal explosion motors, being an extremely important action for the stop of this environmental aggression, has no effect in the minimization of the harm this element does in the positions where its deposition now lays. The impact of the ubiquity of pollution, in this case Lead pollution, needs to have monitoring tools. The greatest of the tools one can have is the analysis of the content of a strong indicator. One that stands for a long time in one place, for which it is able to receive the marks of the analyte passage. Quercus suber (Cork Oak) tree is such a case. Having a life expectation ranging from 200 to 500 years (depending on the cork extraction intensity) and with a capability of regeneration of its cork coverture, it concentrates the amounts of Lead, with which it had contacted through its life, in successive layers, corresponding, the larger ones, to the high temperatures season, and the thinner ones to the low temperatures season. So, the analysis of the content of the element in a layer of cork with a given amount of years in the tree, will be a good estimator of how the content of Lead as evolved in the area. And a correct distribution of sampling trees will show much more about a greater area. The possibility of choosing years by choosing layers of cork, and the fact that the sampling will not harm the tree, if properly done, make this procedure a novel and powerful tool in the monitorization of the dispersion of heavy metals in areas populated by Quercus suber, as it is the case of big areas in Portugal, the great of the greatest in everything related with this tree, namely economically, and, in general, in the area of the Mediterranean basin. This paper announces how the electroanalytical determination of Pb(II) by Differential Pulse Anodic Stripping Voltammetry (DPASV), recently done in the Department of Chemistry of the University of Évora, already accepted for publication in Portugaliae Electrochimica Acta, has proven to allow a deeper insight into the previously discussed problematic

Multi-robot cognitive formations

In this paper, we show how a team of autonomous mobile robots, which drive in formation, can be endowed with basic cognitive capabilities. The formation control relies on the leader-follower strategy, with three main pair-wise con-figurations: column, line and oblique. Furthermore, non-linear attractor dynamics are used to generate basic robotic behaviors (i.e. follow-the-leader and avoid obstacles). The control archi-tecture of each follower integrates a representation of the leader (target) direction, which supports leader detection, selection between multiple leaders (decision) and temporary estimation of leader direction (short-term memory during occlusion and prediction). Formalized as a dynamic neural field, this additional layer is smoothly integrated with the motor movement control system. Experiments conducted in our 3D simulation software, as well as results from the implementation in middle size robotic platforms, show the ability for the team to navigate, whilst keeping formation, through unknown and unstructured environments and is robust against ambiguous and temporarily absent sensory information.Fundação para a Ciência e a Tecnologia (FCT) - FCOMP-01-0124-FEDER-022674Fundos FEDER - Programa Operacional Fatores de Competitividade - COMPET

Processing and characterization of glass-ceramic foams belonging to the Li2O-ZrO2-Al2O3-SiO2 (LZSA) system produced by gelcasting

In this work the viscosimetry technique was used to evaluate the rheological characteristics of ceramic suspensions prepared with a LZSA (Li2O-ZrO2-SiO2-Al2O3) glass. From the rheological characterization it was possible to establish optimized conditions of solid fraction, dispersant, organic monomers and foaming agent for the production of glass-ceramic foams by gelcasting. The resulting foams were subjected to heattreatments at 200-500ºC/60 min, for degradation of organics and at 950ºC/60 min for sintering and crystallization. With the obtained porous ceramic bodies linear thermal shrinkage, apparent density and mechanical strength measurements as well as microstructural analysis were performed. The adaptation of the rheological characteristics of the LZSA parent glass powder with the gelcasting processing technique allowed the production of ceramic foams with high open and interconnected porosity (>90%) with good thermal stability and with mechanical strength suitable for the production of porous ceramics.Neste trabalho, a técnica de viscosimetria foi utilizada para avaliar as características reológicas de suspensões preparadas com precursor vitrocerâmico do sistema LZSA (Li2O-ZrO2-SiO2-Al2O3). A partir da caracterização reológica, foi possível estabelecer condições composicionais adequadas de fração de sólidos, dispersante e monômeros orgânicos. A quantidade de agente espumante para produção de espumas vitrocerâmicas por gelcasting foi determinada pela variação volumétrica após agitação. As espumas resultantes foram submetidas a tratamentos térmicos no intervalo de temperatura compreendido entre 200 e 500ºC/60 min, para degradação da matéria orgânica e a 950ºC/60 min para sinterização e cristalização. Com os corpos cerâmicos porosos foram realizadas medidas de retração térmica, densidade aparente, análise microestrutural e resistência mecânica. A adequação das características reológicas do precursor LZSA por gelcasting permitiu a produção de espumas com elevada porosidade (> 90%) aberta e interconectada com boa estabilidade térmica e com resistência mecânica compatível com cerâmicas [email protected]@[email protected]@emc.ufsc.brUniversidade Federal de Santa Catarina Departamento de Engenharia Mecânica Programa de Pós-Graduação em Ciência e Engenharia de MateriaisCentro Universitário Barriga Verde - UNIBAVEUniversidade Federal de São Paulo (UNIFESP) Departamento de Ciência e TecnologiaUNIFESP, Depto. de Ciência e TecnologiaSciEL

Produção de mudas de Noni (Morinda citrifolia L.).

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