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It is difficult to control and to manage wells’ start-up in offshore platforms. In order to solve this problem an intelligent system can play an important role, since available qualitative operator and design knowledge can be easily implemented to assist the operator during wells’ start-up. This paper describes the integration of an expert system associated with anti-slug control for well start-up. The intelligent system has many heuristic rules to implement the automation of the start-up procedures, like the opening choke valve while simultaneously respecting many constraints. Severe slugging flow regimes are one of the major disturbances for the operation of offshore production platforms, and can cause many unplanned shutdowns. Therefore, it’s important to combine start-up intelligent system with an anti-slug advanced control module for each well. The benefits are associated to reducing possibility of unplanned shutdowns during well start-up operational procedures, decreasing operators’ stress and also helping to minimizing impacts to the environment. A prototype was implemented in one platform with good results for a safe and efficient wells start-up procedure. This paper will present the development and results of this intelligent system for wells’ start-up and anti-slug control for offshore platforms.

An artificial neural network (ANN) calibration model was developed to determine aluminum in the presence of iron in soil extracts, using xylenol orange as chromogenic reagent. The spectral data of synthetic mixtures of Al(3+) and Fe(3+) as well as of the soil extracts, were recorded in the range between 410 and 580 nm. Method validation was carried out using 18 soil extracts. The results gave good linear correlations between the ANN model and the ICP OES measurements for both species.

This paper reports an approach for quantification of Lactobacillus in fermented milk, grown in a selective medium (MRS agar), by use of digital colour images of Petri plates easily obtained by use of a flatbed scanner. A one-dimensional data vector was formed to characterize each digital image on the basis of the frequency-distribution curves of the red (R), green (G), and blue (B) colour values, and quantities derived from them, for example lightness (L), relative red (RR), relative green (RG), and relative blue (RB). The frequency distributions of hue, saturation, and intensity (HSI) were also calculated and included in the data vector used to describe each image. Multivariate non-linear modelling using the least-squares support vector machine (LS-SVM) and a linear model based on PLS regression were developed to relate the microbiological count and the frequency vector. Feasibly models were developed using the LS-SVM and errors were below than 10% for Lactobacillus quantification, indicating the proposed approach can be used for automatic counting of colonies.

The isomeric triterpenes oleanoic acid and ursolic acid are compounds exhibiting a variety of biological activities. Structurally, they differ only in the position of the methyl group (C-29) at ring E. The differentiation of these two compounds requires a detailed analysis of their 13C and 1H NMR spectra which is often tedious and time-consuming, besides the need of using deuterated solvents. In this work, we report the use of bidimensional Raman spectroscopy as a fast technique to distinguish these two bioactive isomeric compounds.

This work describes the optimized conditions for the preparation of cobalt aluminum silicate complexes through a simplified methodology. These materials, designated CoAlSi-NHG, were obtained by a non-hydrolytic sol–gel route involving the condensation of aluminum chloride with diisopropylether in the presence of cobalt chloride, followed by reaction with tetraethoxysilane. The obtained solids were heat-treated at various temperatures, and the resulting materials were characterized by ultraviolet-visible spectroscopy, X-ray diffraction, 29 Si and 27 Al NMR, transmission electron microscopy, surface area, thermogravimetric analysis, and differential thermal analysis. All the materials consisted of an aluminum silicate matrix, and they all remained amorphous throughout heat treatment up to 750 °C. The onset of crystallization took place at 1000 °C, and the formation of mullite was observed thereafter. All the CoAlSi-NHGs obtained in this work via different heat treatments were used as catalysts in the oxidation of ( Z )-cyclooctene, cyclohexane, and n -heptane by iodozylbenzene. The non-hydrolytic sol–gel route led to the obtention of extremely interesting catalytic systems capable of selectively oxidizing various types of reactions. The intermediate species is the oxidizing species oxo-cobalt, which is similar to the active species obtained in the case of enzymes such as cytochrome P-450.

This work describes the synthesis of a first-generation iron porphyrin catalyst entrapped in a silica matrix by the sol–gel route, leading to spherical particles. The catalyst was synthesized by the method of Stober, through hydrolysis and condensation of the alkoxysilane TEOS in a mixture of alcohol, water and ammonia, in the presence of the iron porphyrin Fe(TPP)Cl. The relation between particle morphology and catalytic activity of the different Fe(TPP)–SiO 2 , obtained using different H 2 O/silane molar ratios and ammonia concentrations in the xerogel syntheses, was studied. The obtained catalysts were characterized by UV–vis spectroscopy, NMR 29 Si, thermogravimetric analysis and transmission electron microscopy. Their ability to catalyze ( Z )-cyclooctene epoxidation and cyclohexane oxidation was tested using iodosylbenzene as oxygen donor; the oxidation products were analyzed by gas chromatography and the catalysts obtained in a form of particles spherical and monodispersed showed to be a promising catalytic system for selective oxidation.

In this work, we report the synthesis and the photoluminescence features of Eu(III)-doped yttrium-aluminium oxide obtained by non-hydrolytic sol-gel routes. After heating the powders above 600 ºC the XRD patterns show the presence of the Y4Al2O9 (YAM) and Y3Al5O12 (YAG) phases. At 800 and at 1500 ºC the PL spectra display the Eu(III) lines characteristic of the YAM monoclinic phase. The 5D0->7F2 transition is favored relatively to the 5D0->7F1 lines. However, at 1100 ºC the cubic YAG is the preferential phase and the 5D0->7F1 transition dominates the spectrum. The Eu(III) ions lie in a centrosymmetrical site. The different solvents used in the sol-gel synthesis also change the relative proportion between these two phases. This is monitored analyzing the modifications in the relative intensity between the 5D0->7F2 and the 5D0->7F1 transitions.

The sol–gel method using metal alkoxide has been investigated to prepare aluminum–yttrium oxide as yttrium–aluminum garnet (YAG) matrix composite fiber. In this paper we investigate the influence of yttrium content and temperature in the synthesis of Eu(III)-doped aluminum–yttrium oxide by non-hydrolytic sol–gel route. The formation process and the local structure of the samples were discussed by means of X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and photoluminescence (PL) spectroscopy. For temperatures around 800 °C, initial crystallization was observed and the phases Y4Al2O9 (YAM) and Y3Al5O12 (YAG) appear. For samples treated at 800 and 1500 °C the emission spectra display preferentially the f–f transitions characteristic of the YAM monoclinic phase, whereas the YAG cubic appears as the favored phase at 1100 °C, in accordance with the Eu(III) centrosymmetrical local site.

This work describes the preparation of the iron (III) porphyrin, FeTDCNO2, entrapped in a silica matrix in the form of powder (FePD) or thin film using the sol-gel process. The films were obtained from sols using the dip-coating technique. The variables involved in the FePD preparation were analysed by a fractional factorial design with resolution 5, designated by 2 V 5 − 1. The variables which present a positive effect and maximise the loading of the studied ironporphyrin on the FePD material are solvent, water volume and reaction time. The utilization of pyridine or imidazole as template does not affect the preparation of the FePD material. The UV-visible absorption spectra of all prepared materials present the characteristic Soret band of ironporphyrins at 419–420 nm. The materials were analysed by thermogravimetric analysis, isotherm of nitrogen adsorption, 29Si NMR and scanning electron micrograph. The catalytic performance of FePD-imidazole on the epoxidation of z-cyclooctene with iodosylbenzene is similar to that of FeTDCNO2 in homogeneous solution (60 and 52%).

The optimised conditions for preparation of ironporphyrin (FeP)-template trapped silica obtained by the sol–gel process are analysed by fractional factorial design. The FeP iron 5,10,15,20-tetrakis(pentafluorophenyl)-porphyrin (FeTFPPCl), iron 5,10,15,20-tetrakis(2,6-dichlorophenyl-3-sulphonatophenyl)-porphyrin (FeTDCSPP(Na)4Cl), iron 5,10,15,20-tetrakis-p-carboxyphenylporphyrin (FeTCPP(Na)4Cl) and iron 5,10,15,20-tetrakis-p-methylpyridilporphyrin (FeTMPyP(Cl)5) were used. Pyridine or 4-phenylimidazole was used as template. Scanning electron microscopy (SEM) shows that the use of different porphyrins and conditions in the preparation of xerogel produce different product morphologies. The prepared materials have surface areas, between 300 and 1000 m2/g. The electron paramagnetic resonance spectra of trapped materials have characteristic signal of FeIII high spin, the presence of porphyrin species in a rhombic symmetry and porphyrin aggregates were also observed.

A neuro-genetic approach was developed to optimise an automated procedure for the spectrophotometric determination of cobalt in bovine liver, fish and mussel samples by using a monosegmented flow system. The method exploited the Co(II) catalysed oxidation of Tiron by hydrogen peroxide. The values related to reagent concentrations and mean residence time were optimised in terms of slope and correlation coefficient of the calibration curve. The neural networks were used to model the system, relating the parameters of the monosegmented flow system with those of the calibration curve. The genetic algorithm was applied to attain the optimum values from the model developed by the neural networks. The detection and quantification limits were 1.66 and 5.33 ng l 1 Co, respectively. © 2001 Elsevier Science B.V. All rights reserved.

Novel hybrid organic–inorganic catalysts constituted by iron(III) or manganese(III) 5,10,15,20-tetrakis(pentafluorophenyl) porphyrin entrapped in an alumina amorphous matrix have been prepared. The hybrid materials were obtained by a non-hydrolytic sol–gel route, through the condensation of aluminium chloride with diisopropyl ether in the presence of metalloporphyrin. The presence of the metalloporphyrin entrapped in the alumina matrix is confirmed by ultraviolet–visible spectroscopy and electron spectroscopic imaging. The material was also analysed by infrared spectroscopy, selected area diffraction, scanning electron microscopy, thermogravimetric analysis and differential thermal analysis, and its surface area was determined. Comparison between the leaching of metalloporphyrin from non-hydrolytic materials and adsorbed metalloporphyrin on commercial neutral alumina confirms that in the non-hydrolytic materials the metalloporphyrin is entrapped and not just adsorbed on the alumina surface. The use of a conventional hydrolytic sol–gel process leads to the complete leaching of the metalloporphyrin from the matrix, underlining the importance of the non-hydrolytic alumina gel process in the matrix preparation. The prepared alumina matrix materials are amorphous, even after heat treatment up 270 °C. The new catalysts prepared were tested for their ability to catalyse the epoxidation of (Z)-cyclooctene using iodosylbenzene as oxygen donor, giving high yields in the epoxidation, similar to those obtained using the metalloporphyrin in solution or supported on a silica matrix.

A partial least squares (PLS) calibration model was developed for the simultaneous spectrophotometric determination of Al and Fe in plant extracts by using an excess of xylenol orange as the cromogenic reagent. Experimental conditions were established to reduce interferences, decrease system complexity and produce a robust procedure that could be used for routine analysis. The spectra should be recorded from 2 to 4 h after mixing the reagents. Ethanolic solutions were used to improve the formation of the Al-XO complexes. The best calibration model was obtained using the PLS-2 algorithm after mean centering the data with five latent variables. Under the experimental conditions adopted, only Zn was found to be a potential interfering species with the plant extracts used. Validation of the proposed spectrophotometric method was performed by running nine plant samples from the 1997 International Plant-Analytical Exchange (IPE) which were also analyzed by ICP-AES for further correlation. The proposed procedure showed to be useful for prediction of Al and Fe values from 12.5 to 2500 mg kg −1 in plant dry weight basis.

Neural networks with pruning were applied to model overlapped peaks obtained in differential pulse voltammetry (DPV) with modified carbon fibre electrode with TiO 2 of binary mixtures of catechol and hydroquinone. The best condition for electrochemical response was obtained with 0.05 mol l 1 Tris‐HCl buffer at pH 6.0 and T-800 sized carbon fibre electrode. Initially the voltammograms were processed using Fourier transform filter and principal component analysis (PCA) to noise reduction and data compression, respectively. The scores of these principal components were the input into the neural network and the optimal brain surgeon (OBS) was the procedure employed for pruning the neural network. The results obtained with pruning procedure were slightly better in relation to hydroquinone in comparison to the PLS1 and PLS2. However, the similar errors were obtained to catechol when using PLS or neural networks models. Using neural networks with pruning was possible to determine catechol and hydroquinone by DPV using carbon fibre electrode, in concentration range of 1.0 10 4 up to 6.010 4 mol l 1 with root mean square errors of predictions (%RMSEP) of 7.42 and 8.02, respectively. The good results show that the proposed methodology is a good alternative to simultaneous determination of catechol and hydroquinone in binary mixtures. © 2000 Elsevier Science B.V. All rights reserved.

In a biosensor for salicylate, developed using a modified carbon paste electrode with silica gel coated with Meldola's Blue and salicylate hydroxylase, the current time series presented a complex oscillatory pattern, for salicylate and NADH concentrations close to 2.0 × 10−5 and 3.6 × 10−5 mol 1−1, respectively. These experimental results suggest that the biosensor response presents chaotic characteristics. The complex temporal behavior of these series was diagnosed as deterministic chaos by measurement of the Grassberger-Procaccia dimension, and the calculation of the first Lyapunov exponent. The value determined for the correlational dimension is lower than 5. These results suggest a coupling of five or six differential equations to describe the redox reactions of the biosensor system.

An anomalous solution behavior at the molecular scale was observed for macroscopically homogeneous mixtures of methanol and ethanol. Two-dimensional Raman correlation spectroscopy was used to elucidate the possible existence of microstructures formed in the mixture. The result suggests that separate methanol and ethanol clusters are formed without heterohydrogen bonding between different alcohol species. Supramolecular structures seem to be formed by the interaction of such clusters with each other through cohesion and dispersion forces, but not through direct hydrogen bonding connections.