Effects of storage, processing and proteolytic digestion on microcystin-LR concentration in edible clams

Accumulation of microcystin-LR (MC-LR) in edible aquatic organisms, particularly in bivalves, is widely documented. In this study, the effects of food storage and processing conditions on the free MC-LR concentration in clams (Corbicula fluminea) fed MC-LR-producing Microcystisaeruginosa (1 × 105 cell/mL) for four days, and the bioaccessibility of MC-LR after in vitro proteolytic digestion were investigated. The concentration of free MC-LR in clams decreased sequentially over the time with unrefrigerated and refrigerated storage and increased with freezing storage. Overall, cooking for short periods of time resulted in a significantly higher concentration (P < 0.05) of free MC-LR in clams, specifically microwave (MW) radiation treatment for 0.5 (57.5%) and 1 min (59%) and boiling treatment for 5 (163.4%) and 15 min (213.4%). The bioaccessibility of MC-LR after proteolytic digestion was reduced to 83%, potentially because of MC-LR degradation by pancreatic enzymes. Our results suggest that risk assessment based on direct comparison between MC-LR concentrations determined in raw food products and the tolerable daily intake (TDI) value set for the MC-LR might not be representative of true human exposure.

The Crystal Structure of the Escherichia coli Autoinducer-2 Processing Protein LsrF

PLOS ONE, 4(8):ARTe6820

Modelling of the kinetics of municipal solid waste composting in full-scale mechanical-biological treatment plants

A thesis submitted in fulfilment of the requirements for the Degree of Doctor of Philosophy in Sanitary Engineering in the Faculty of Sciences and Technology of the New University of Lisbon

ROAZ and ROAZ II Autonomous Surface Vehicle Design and Implementation

International Lifesaving Congress 2007, La Coruna, Spain, December, 2007

A New ROV Design: Issues on Low Drag and Mechanical Symmetry

This paper reports the design of a new remotely operated underwater vehicle (ROV), which has been developed at the Underwater Systems and Technology Laboratory (USTL) - University of Porto. This design is contextualized on the KOS project (Kits for underwater operations). The main issues addressed here concern directional drag minimization, symmetry, optimized thruster positioning, stability and layout of ROV components. This design is aimed at optimizing ROV performance for a set of different operational scenarios. This is achieved through modular configurations which are optimized for each different scenario.

Incidence of respiratory viruses in preterm infants submitted to mechanical ventilation

The objectives of this study were to determine the incidence of infection by respiratory viruses in preterm infants submitted to mechanical ventilation, and to evaluate the clinical, laboratory and radiological patterns of viral infections among hospitalized infants in the neonatal intensive care unit (NICU) with any kind of acute respiratory failure. Seventy-eight preterm infants were studied from November 2000 to September 2002. The newborns were classified into two groups: with viral infection (Group I) and without viral infection (Group II). Respiratory viruses were diagnosed in 23 preterm infants (29.5%); the most frequent was respiratory syncytial virus (RSV) (14.1%), followed by influenza A virus (10.2%). Rhinorrhea, wheezing, vomiting and diarrhea, pneumonia, atelectasis, and interstitial infiltrate were significantly more frequent in newborns with nosocomial viral infection. There was a correlation between nosocomial viral infection and low values of C-reactive protein. Two patients with mixed infection from Group I died during the hospital stay. In conclusion, RSV was the most frequent virus in these patients. It was observed that, although the majority of viral lower respiratory tract infections had a favorable course, some patients presented a serious and prolonged clinical manifestation, especially when there was concomitant bacterial or fungal infection.

An evaluation of manual and mechanical methods to identify Candida spp. from human and animal sources

To compare two yeast identification methods, i. e, the manual and the VITEK mechanical methods, 62 clinical samples from hemocultures and animal sources were analyzed. After identification as Candida yeasts by the VITEK method, the strains were recharacterized using manual assimilation methods and sugar fermentation tests. Our findings reveal 58% concurrent identification between the two methods for animal strains, and 51% for human hemoculture strains.

Probabilistic models for mechanical properties of prestressing strands

This study focus on the probabilistic modelling of mechanical properties of prestressing strands based on data collected from tensile tests carried out in Laboratório Nacional de Engenharia Civil (LNEC), Portugal, for certification purposes, and covers a period of about 9 years of production. The strands studied were produced by six manufacturers from four countries, namely Portugal, Spain, Italy and Thailand. Variability of the most important mechanicalproperties is examined and the results are compared with the recommendations of the ProbabilisticModel Code, as well as the Eurocodes and earlier studies. The obtained results show a very low variability which, of course, benefits structural safety. Based on those results, probabilistic modelsfor the most important mechanical properties of prestressing strands are proposed.

Febrifugine derivative antimalarial activity: quantum mechanical predictors

Plasmodium falciparum resistant strain development has encouraged the search for new antimalarial drugs. Febrifugine is a natural substance with high activity against P. falciparum presenting strong emetic property and liver toxicity, which prevent it from being used as a clinical drug. The search for analogues that could have a better clinical performance is a current topic. We aim to investigate the theoretical electronic structure by means of febrifugine derivative family semi-empirical molecular orbital calculations, seeking the electronic indexes that could help the design of new efficient derivatives. The theoretical results show there is a clustering in well-defined ranges of several electronic indexes of the most selective molecules. The model proposed for achieving high selectivity was tested with success.

The effect of adhesive thickness on the mechanical behavior of a structural polyurethane adhesive

One parameter that influences the adhesively bonded joints performance is the adhesive layer thickness. Hence, its effect has to be investigated experimentally and should be taken into consideration in the design of adhesive joints. Most of the results from literature are for typical structural epoxy adhesives which are generally formulated to perform in thin sections. However, polyurethane adhesives are designed to perform in thicker sections and might have a different behavior as a function of adhesive thickness. In this study, the effect of adhesive thickness on the mechanical behavior of a structural polyurethane adhesive was investigated. The mode I fracture toughness of the adhesive was measured using double-cantilever beam (DCB) tests with various thicknesses of the adhesive layer ranging from 0.2 to 2 mm. In addition, single lap joints (SLJs) were fabricated and tested to assess the influence of adhesive thickness on the lap-shear strength of the adhesive. An increasing fracture toughness with increasing adhesive thickness was found. The lap-shear strength decreases as the adhesive layer gets thicker, but in contrast to joints with brittle adhesives the decrease trend was less pronounced.

Effects of tissue handling and processing steps on PCR for detection of Mycobacterium tuberculosis in formalin-fixed paraffin-embedded samples

Development and standardization of reliable methods for detection of Mycobacterium tuberculosis in clinical samples is an important goal in laboratories throughout the world. In this work, lung and spleen fragments from a patient who died with the diagnosis of miliary tuberculosis were used to evaluate the influence of the type of fixative as well as the fixation and paraffin inclusion protocols on PCR performance in paraffin embedded specimens. Tissue fragments were fixed for four h to 48 h, using either 10% non-buffered or 10% buffered formalin, and embedded in pure paraffin or paraffin mixed with bee wax. Specimens were submitted to PCR for amplification of the human beta-actin gene and separately for amplification of the insertion sequence IS6110, specific from the M. tuberculosis complex. Amplification of the beta-actin gene was positive in all samples. No amplicons were generated by PCR-IS6110 when lung tissue fragments were fixed using 10% non-buffered formalin and were embedded in paraffin containing bee wax. In conclusion, combined inhibitory factors interfere in the detection of M. tuberculosis in stored material. It is important to control these inhibitory factors in order to implement molecular diagnosis in pathology laboratories.

Analysis of Natural and Artificial Phenomena Using Signal Processing and Fractional Calculus

In this paper we study several natural and man-made complex phenomena in the perspective of dynamical systems. For each class of phenomena, the system outputs are time-series records obtained in identical conditions. The time-series are viewed as manifestations of the system behavior and are processed for analyzing the system dynamics. First, we use the Fourier transform to process the data and we approximate the amplitude spectra by means of power law functions. We interpret the power law parameters as a phenomenological signature of the system dynamics. Second, we adopt the techniques of non-hierarchical clustering and multidimensional scaling to visualize hidden relationships between the complex phenomena. Third, we propose a vector field based analogy to interpret the patterns unveiled by the PL parameters.

Development and implementation of strategies for the incorporation of reinforcing elements in aluminium alloys by solid state processing

Dissertação para obtenção do Grau de Mestre em Engenharia Mecânica

Long-term biosignals visualization and processing

Thesis submitted in the fulfillment of the requirements for the Degree of Master in Biomedical Engineering