New analytical procedure based on a cellulose bag and ionic exchanger with p-aminobenzoic acid groups for differentiation of labile and inert metal species in aquatic systems

A new procedure was developed for the in situ characterization of the lability of metal species in aquatic systems by using a system equipped with a diffusion membrane and cellulose organomodified with p-aminobenzoic acid groups (DM-Cell-PAB). To this end, the DM-Cell-PAB system was prepared by adding cellulose organomodified with p-aminobenzoic acid groups (Cell-PAB) to pre-purified cellulose bags. After the DM-Cell-PAB system was sealed, it was examined in the laboratory to evaluate the influence of complexation time, mass of exchanger, pH, metal ions (Cu, Cd, Fe, Mn, and Ni), and concentration of organic matter on the relative lability of metal species. It was found that the pH and kinetics strongly influence the process of metal complexation by the DM-Cell-PAB system. At all pH levels, Cd, Mn, and Ni showed lower complexation with Cell-PAB resin than Cu and Fe metals. Note that relative lability of metals complexed to aquatic humic substances (AHS) in the presence of Cell-PAB resin showed the following order: Cu congruent to Fe >> Ni > Mn=Cd. The results presented here also indicate that increasing the AHS concentration decreases the lability of metal species by shifting the equilibrium to AHS-metal complexes. Our results indicate that the system under study offers an interesting alternative that can be applied to in situ experiments for differentiation of labile and inert metal species in aquatic systems.

Analytical Methods in Photoelectrochemical Treatment of Phenol

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Liquid crystalline formulations containing modified surface TiO2 nanoparticles obtained by sol-gel process

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Monitoring pharmaceuticals photo-Fenton degradation process by using Solid Phase Extraction and liquid chromatography

The recovery of the pharmaceuticals bezafibrate and tetracycline from water was evaluated, using Solid Phase Extraction (SPE) with the aim of applying this technique to interrupt the pharmaceuticals' photodegradation by photo-Fenton process for further analysis. Sep-Pack C-18, Strata X, and Oasis HLB cartridges were evaluated. Oasis HLB showed the most satisfactory recovery and repeatability results: 98% (CV - 1%) for bezafibrate (20.0 mg L-1) and 76% (CV = 1%) for tetracycline (25.0 mg L-1). There was not a significant decrease in recovery at lower concentrations of the pharmaceuticals, and neither when present in Sewage Treatment Plant (STP) effluent matrix.

Avaliação da qualidade dos óleos de fritura usados em restaurantes, lanchonetes e similares

A fritura é uma operação importante por ser um processo de preparação rápida de alimentos e por conferir aos produtos fritos características únicas de odor e sabor. Na temperatura de fritura o óleo interage com o ar, água e componentes dos alimentos que estão sendo fritos gerando compostos responsáveis por odores desagradáveis e degradações em óleos utilizados por longos períodos. Este trabalho foi conduzido com o objetivo de determinar os níveis de alteração dos óleos e gorduras utilizadas nos processos de fritura de restaurantes, lanchonetes, bares e pastelarias da cidade de São José do Rio Preto-SP. Os métodos analíticos aplicados para a avaliação da alteração em 60 amostras de óleos e gorduras incluíram a determinação de compostos polares totais (%), ácidos graxos livres (%, expressos em ácido oléico) e índice de peróxidos (meq/kg). Foram estabelecidos como limite de alteração 25% para compostos polares, 1% para ácidos graxos livres e 15meq/kg para índice de peróxidos. de acordo com os resultados obtidos, observou-se que das 60 amostras analisadas, 30% apresentaram valores de compostos polares superiores ao limite estabelecido para descartar os óleos e gorduras de fritura. Já, para ácidos graxos livres e índice de peróxidos, 18,3% e 8,3% das amostras, respectivamente, apresentaram valores acima do estabelecido para o descarte. Os elevados níveis de compostos polares totais encontrados (57,4%) em um número significativo de amostras demonstraram a necessidade de melhorar a qualidade dos óleos e gorduras de fritura neste setor de alimentação.

Thermodynamic properties of water sorption of jackfruit (Artocarpus heterophyllus Lam.) as a function of moisture content

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of aging on the stability of ceramic foams prepared by thermostimulated sol-gel process

This work presents a new route of preparation of zirconium ceramic foams based on the thermostimulated sol-gel process. This method produces gelled bodies with up to 90% of porosity in the wet gel and can be used to make complex-shaped components. Unfortunately, the shrinkage during the drying step allows to a catastrophic reduction (50%) of the foam porosity. To improve the foam stability we carried out a systematic study of the effect of gel foam aging on the drying process. Samples were aged in closed vessel at 25 C during different time period (from 6 to 240 h). The shrinkage and the mass loss during drying at 50 C were measured in situ, using a non-contact technique performed with a special apparatus. The results show that the total linear shrinkage decreases from 46% to 8% as the aging period increase from 6 to 240 h. This behavior is followed by a small change of total mass loss, from 42 to 54%. It indicates that by aging the structural stiffness of the foams increases due to secondary condensation reactions. Thus, by controlling the aging period, the porosity can be increased from 67 to 75% and the average size of mesopores of dried foams can be screened from 0.3 to 0.9 mum. Finally, these results demonstrate that the thermostimulated sol-gel transition provides a potential route to ceramic foams manufacture.

Wordnet.Br: An Exercise of Human Language Technology Research

This paper reports the ongoing project (since 2002) of developing a wordnet for Brazilian Portuguese (Wordnet.Br) from scratch. In particular, it describes the process of constructing the Wordnet.Br core database, which has 44,000 words organized in 18,500 synsets Accordingly, it briefly sketches the project overall methodology, its lexical resourses, the synset compilation process, and the Wordnet.Br editor, a GUI (graphical user interface) which aids the linguist in the compilation and maintenance of the Wordnet.Br. It concludes with the planned further work.

Yttrium oxysulfide nanosized spherical particles doped with Yb and Er or Yb and Tm: efficient materials for up-converting phosphor technology field

This work reports on the preparation, structural and luminescent studies of nanosized up-converter phosphors Y2O2S:Yb(4%), Er(0.1%) and Y2O2S:Yb(4%), Tm(0.1%),both from polymeric and basic carbonate precursors. The precursors were submitted to a sulphuration process that was previously developed for oxysulfide preparation from basic carbonate. From XRD data, all phosphors presented the oxysulfide phase and the mean crystallite size estimated from the Scherrer formula in the range of 15-20 nm. Polymeric precursor leads to the smallest crystallite size independent on the doping ion. SEM and TEM results confirmed that basic carbonate leads to spherical particles with narrow size distribution and mean diameter of 150 nm, and polymeric precursor smaller spherical particles with diameter between 20 and 40 nm. Up-conversion studies under 980 nm laser excitation showed that Er-doped phosphors present strong green emission related to H-2(11/2), S-4(3/2) --> I-4(15/2) Er transitions as well as the red ones, F-4(9/2) --> I-4(15/2). Tm-doped samples show strong blue emission assigned to (1)G(4) --> H-3(6) and also the red ones, related to (1)G(4) --> F-3(4). Therefore, the sulphuration method was successfully applied to prepare nanosized and nanostructured blue and green up-converter oxysulfide phosphors starting from basic carbonate and polymeric precursors. (C) 2003 Elsevier B.V. All rights reserved.

Difference variance dispersion graphs for comparing response surface designs with applications in food technology

Variance dispersion graphs have become a popular tool in aiding the choice of a response surface design. Often differences in response from some particular point, such as the expected position of the optimum or standard operating conditions, are more important than the response itself. We describe two examples from food technology. In the first, an experiment was conducted to find the levels of three factors which optimized the yield of valuable products enzymatically synthesized from sugars and to discover how the yield changed as the levels of the factors were changed from the optimum. In the second example, an experiment was conducted on a mixing process for pastry dough to discover how three factors affected a number of properties of the pastry, with a view to using these factors to control the process. We introduce the difference variance dispersion graph (DVDG) to help in the choice of a design in these circumstances. The DVDG for blocked designs is developed and the examples are used to show how the DVDG can be used in practice. In both examples a design was chosen by using the DVDG, as well as other properties, and the experiments were conducted and produced results that were useful to the experimenters. In both cases the conclusions were drawn partly by comparing responses at different points on the response surface.

Treatment of 1,10-phenanthroline laboratory wastewater using the solar photo-Fenton process

The red Fe2+-phenanthroline complex is the basis of a classical spectrophotometric method for determination of iron. Due to the toxicity of this complexing agent, direct disposal of the wastewaters generated in analytical laboratories is not environmentally safe. This work evaluates the use of the solar photo-Fenton process for the treatment of laboratory wastewaters containing phenanthroline. Firstly, the degradation of phenanthroline in water was evaluated at two concentration levels (0.1 and 0.01%, w/v) and the efficiencies of degradation using ferrioxalate (FeOx) and ferric nitrate were compared. The 0.01% w/v solution presented much higher mineralization, achieving 82% after 30 min of solar irradiation with both iron sources. The solar photo-Fenton treatment of laboratory wastewater containing, in addition to phenanthroline, other organic compounds such as herbicides and 4-chlorophenol, equivalent to 4500 mg L-1 total organic carbon (TOC) resulted in total degradation of phenanthroline and 25% TOC removal after 150 min, in the presence of either FeOx or ferric nitrate. A ratio of 1: 10 dilution of the residue increased mineralization in the presence of ferrioxalate, achieving 38% TOC removal after 120 min, while use of ferric nitrate resulted in only 6% mineralization over the same period. (c) 2007 Elsevier B.V. All rights reserved.

Product development process: Using real options for assessments and to support the decision-making at decision gates

Enterprises need continuous product development activities to remain competitive in the marketplace. Their product development process (PDP) must manage stakeholders' needs - technical, financial, legal, and environmental aspects, customer requirements, Corporate strategy, etc. -, being a multidisciplinary and strategic issue. An approach to use real option to support the decision-making process at PDP phases in taken. The real option valuation method is often presented as an alternative to the conventional net present value (NPV) approach. It is based on the same principals of financial options: the right to buy or sell financial values (mostly stocks) at a predetermined price, with no obligation to do so. In PDP, a multi-period approach that takes into account the flexibility of, for instance, being able to postpone prototyping and design decisions, waiting for more information about technologies, customer acceptance, funding, etc. In the present article, the state of the art of real options theory is prospected and a model to use the real options in PDP is proposed, so that financial aspects can be properly considered at each project phase of the product development. Conclusion is that such model can provide more robustness to the decisions processes within PDP.

Surface-enhanced resonance Raman scattering as an analytical tool for single molecule detection

A perylene derivative, n-(n-butyl)-n'-(4-aminobutyl) perylene-3,4,9,10-tetracarboxylic acid diimide (simplified as nBu-PTCD-(CH2)(4)-NH2) has been chosen as the target molecule for studies involving single molecule detection (SMD) using Raman scattering. The enhancement of the Raman signal is the result of the multiplicative effects of two phenomena, resonance Raman scattering (RRS) and surface-enhanced Raman scattering (SERS), which leads to the resulting surface-enhanced resonance Raman scattering (SERRS) process. The SERRS spectra from a single molecule have been collected using both silver and gold colloids. The SMD detection of the fundamental vibrational frequencies characteristic of nBu-PTCD-(CH2)(4)-NH2 is complemented with the detection of some overtones and combinations from ring stretching modes at the single molecule level. The background characterization of the ensemble vibrational spectroscopy of the target perylene and its SERRS is also presented, which includes the UV-vis absorption, experimental and calculated Raman scattering and infrared absorption, and molecular organization using reflection-absorption infrared spectroscopy (RAIRS).

Plasma nitriding of sintered AISI 316L at several temperatures

Samples of sintered AISI 316L stainless steel were plasma nitrided in a mixture of H-2-20% N-2, for 3 or 4 h. The treatment temperature was selected in 400-550 degreesC interval, in steps of 50 degreesC. X-ray diffraction (glancing angle geometry-GAXRD), conversion electron Mossbauer spectroscopy (CEMS), optical microscopy and Vickers microhardness were used as analytical techniques. For T greater than or equal to 500 degreesC and t = 4 h, a 40-mum layer is formed. The GAXRD results showed a transformation of the austenite gamma phase to the martensite in the sinterization process and showed as well, that the gamma' (Fe4N) phase is the predominant nitride besides small amounts of epsilon-Fe2N, gamma(N) CrN, Cr2O3 and the fcc nitrogen supersatured solid phase gamma(N). The CrN phase seems to decrease with temperature while the gamma(N) phase fraction is almost less than or equal to10%, independently on the temperature. The CEMS results indicated that while the gamma(N) fraction decreases with temperature of plasma nitriding, the gamma' fraction increases proportionally. (C) 2003 Elsevier B.V. All rights reserved.