Intestinal angiodysplasia: diagnosis and therapy

On the basis of two personal cases of angiodysplasia authors describe this rare pathology and its relative diagnostic difficulties. On the grounds of their experience and the international literature on this pathology, authors considered the angiography as the selected method for the diagnosis of intestinal angiodysplasia, and they consider surgical therapy as the best curative method for this pathology.     

Multizone circulating reactor modeling for gas‐phase polymerization. II. Reactor operating with gas barrier in the downer section

A new gas‐phase technology for polyolefin production is being developed to be commercially available for large‐scale production between 2004 and 2005. This new technology uses a multizone circulating reactor, which consists of two interrelated zones where two distinct and different fluodynamic regimes are realized, between which the polymer particles are kept in continuous circulation. In the first part, we presented a mathematical model for the reactor, and this second part of the article we present simulations when a gas barrier is introduced in the top of the downer section and its implications in the polymer characteristics. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1053–1059, 2004     

Application of the essential work of fracture method in ranking the performance in service of high-density polyethylene resins employed in pressure pipes

High-density polyethylene resins have increasingly been used in the production of pipes for water- and gas-pressurized distribution systems and are expected to remain in service for several years, but they eventually fail prematurely by creep fracture. Usual standard methods used to rank resins in terms of their resistance to fracture are expensive and non-practical for quality control purposes, justifying the search for alternative methods. Essential work of fracture (EWF) method provides a relatively simple procedure to characterize the fracture behavior of ductile polymers, such as polyethylene resins. In the present work, six resins were analyzed using the EWF methodology. The results show that the plastic work dissipation factor, βw _p , is the most reliable parameter to evaluate the performance. Attention must be given to specimen preparation that might result in excessive dispersion in the results, especially for the essential work of fracture w _e .     

Integration of computer simulation in design for manufacturing and assembly

As a reason for competitiveness, the process of product development evolves using, in some situations, improvement methods, e.g. design for manufacturing and assembly (DFMA). In the framework of the product development process, it is desirable that engineers and managers have a systemic view of the effects that changes in local processes will have on the overall performance of the entire production system. This vision of such effects can be achieved with computer simulation. This study aims at assessing how DFMA can be integrated with computer simulation and the benefits from the alternatives identified by such method during production and assembly. Using the electronic voting machine printer as object of study, options to improve design by means of DFMA principles are identified. Five models were developed to represent the current assembly process and two models following the implementation of the changes proposed by the DFMA. The sale price is confidential (exclusive product of the Brazilian government). The company provided data in assembly costs. The results show the production increase in assembly time (9.94%) and average daily sales ($415).     

Modeling and simulation of <Emphasis Type="Italic">Bacillus cereus</Emphasis> chitosanase activity during purification using expanded bed chromatography

A phenomenological model was used to describe sequentially the three steps (flowthrough, washing and elution) of expanded bed adsorption chromatography for recovery of chitosanases from Bacillus cereus. Additionally, a hybrid strategy for model parameter estimation was carried out using particle swarm optimization and Gauss-Newton algorithms. The model was validated with independent experimental data and the statistical criteria (χ ² and mean squared error tests) showed that the hybrid strategy was more promising than just the heuristic method. With the calibrated model, surface response methodology was applied to obtain the optimal operational conditions, and experiments were performed to confirm these results. Overall, a value of 41.08% for yield was obtained using 700 mM NaCl during elution. In summary, all approach employed in this work was relevant for maximizing the yield of the chromatographic process.     

A multi-residue method for the determination of pesticides in high water content matrices by gas chromatography-single quadrupole mass spectrometry with electron ionisation (EI-GC/MS)

An EI-GC/MS method for the determination of pesticide residues in vegetable matrices with high water content was validated using papaya samples. The validation of a multi-residue pesticide method was in agreement with national and international regulations enabling the Ministry of the Agriculture, Livestock and Food Supply of Brazil to cover a large number of matrices and pesticide residues in its monitoring and control programmes. The extraction used 60 mL of ethyl acetate and 30 g of sample previously processed. After extraction, clean-up of all the extracts was carried out by percolation through GBC cartridges. The samples were then injected in an EI-GC/MS system. Calibration curves were prepared in quadruplet by fortifying blank extracts with a standard solution containing all the pesticides studied at 0.000, 0.005, 0.010, 0.020, 0.030, 0.050, 0.080 and 0.100 mg kg(-1). For the recovery study, blank samples were fortified at 0.010, 0.020, 0.030, 0.050 and 0.080 mg kg(-1) and then submitted to the extraction procedure. The complete procedure was repeated over four different days by two analysts. The regression parameters of calibration curves were calculated for each validation day. Linearity, selectivity, specificity, robustness, limits of detection and quantification were also assessed. The uncertainty was estimated for each analyte at each spike level studied. The method had recoveries between 91% and 105% and precision results ≤ 20%. Limits of quantification were below or equal to the maximum residue limits (MRLs) regulated by Brazilian legislation. The MRLs of the selected pesticides are not regulated by CODEX Alimentarius. The results are also in agreement with SANCO/10684/2009.     

Determination and confirmation of chloramphenicol in honey, fish and prawns by liquid chromatography-tandem mass spectrometry with minimum sample preparation: validation according to 2002/657/EC Directive

A reliable, simple and sensitive liquid chromatography-electrospray ionisation-tandem mass spectrometry (LC-ESI-MS/MS) confirmation method has been developed for chloramphenicol (CAP) determination in honey, fish and prawns. For honey, samples were extracted with ethyl acetate, an aliquot was evaporated to dryness and re-dissolved in mobile phase. For fish and prawns, tissues were extracted with acetonitrile and chloroform. The organic layer was evaporated to dryness and the residue was re-constituted with water: acetonitrile (90:10). LC separation was achieved on a C18 column with gradient elution using a mobile phase of acetonitrile and water. Analysis was carried out on a triple-quadrupole tandem mass spectrometer in multiple reaction monitoring (MRM) mode via electrospray interface operated in negative ionisation mode, with deuterated chloramphenicol-d(5) (d(5)-CAP) as internal standard. Method validation was performed according to the criteria of Commission Decision 2002/657/EC. Four identification points were obtained for CAP with one precursor ion and two product ions. The limit of detection (LOD) was 0.02 μg kg(-1). Linear calibration curves were obtained over concentration ranges of 0.1-1.0 μg kg(-1) in tissues. Mean recoveries ranged from 85.5% to 115.6%, with the corresponding intra- and inter-day variation ranging from 1.0% to 22.5%, depending on matrix type and level of concentration. The decision limit (CCα) and detection capability (CCβ) of the method were obtained for all matrices: 0.04 and 0.06 μg kg(-1), respectively, for prawns and fish and 0.05 and 0.09 μg kg(-1) for honey.     

A Method to Check and Discover Adulteration of Nebbiolo-Based Monovarietal Musts: Detection of Barbera and Dolcetto cv via SSR Analysis Coupled with Lab-On-Chip® Microcapillary Electrophoresis

The process of wine traceability/authentication is a key target for Italy, the world’s first largest wine producer (around 4.6 million tons in 2010 according to FAOSTAT). Several European countries developed appellation systems, with their own unique labels and seals, trying to fight label fraud that misrepresented the true origins of the wine. Advancements on this topic were provided by Council Regulation (EC) No. 479/2008 on the common organisation of the market in wine. As reported by experts, it is suspected that as much as 5 % of the wine sold in secondary markets worldwide could be counterfeit. Despite the high number of traceability methods, commonly based on the use of time consuming and expensive techniques (SNIF-NMR and stable isotope-ratio mass spectrometry), few applications report the use of polymerase chain reaction directly in musts or in bottled wine. Information on genetic polymorphism given by simple sequence repeats (SSR; microsatellite markers) proved helpful when applied to grape and musts analysis. The limited quantity of amplifiable grape genomic DNA in wine represents the main issue for the application of such analytical approach. Musts are the first intermediate product to be checked, in order to exclude the unintentional or fraudulent contamination with foreign grape varieties. The aims of this work are (1) the selection of performing SSR markers able to discriminate ‘Barbera’ and ‘Dolcetto’ from ‘Nebbiolo’ and (2) the hyphenated use of capillary micro-electrophoresis (lab-on-chip technology) for polymorphisms detection, to highlight the presence of foreign grape in ‘Nebbiolo’ musts produced in purity, as required by the designation disciplinary. Finally, we suggest using this approach by exploiting VVS2 marker in order to detect Barbera and Dolcetto grapes in Nebbiolo musts, waiting for more robust and powerful method to extract and amplify specific DNA from bottled wine.