Luísa Castro

Biological treatment of the effluent from a bleached kraft pulp mill using basidiomycete and zygomycete fungi

Three white-rot fungi (Pleurotus sajor caju, Trametes versicolor and Phanerochaete chrysosporium) and one soft-rot fungi (Rhizopus oryzae) species confirmed their potential for future applications in the biological treatment of effluents derived from the secondary treatment of a bleached kraft pulp mill processing Eucalyptus globulus. Among the four species P. sajor caju and R. oryzae were the most effective in the biodegradation of organic compounds present in the effluent, being responsible for the reduction of relative absorbance (25-46% at 250 nm and 72-74% at 465 nm) and of chemical oxygen demand levels (74 to 81%) after 10 days of incubation. Laccase (Lac), lignin (Lip) and manganese peroxidases (MnP) expression varied among fungal species, where Lac and LiP activities were correlated with the degradation of organic compounds in the effluent treated with P. sajor caju. The first two axes of a principal component analysis explained 88.9% of the total variation among sub-samples treated with the four fungus species, after different incubation periods. All the variables measured contributed positively to the first component except for the MnP enzyme activity which was the only variable contributing negatively to the first component. Absorbances at 465 nm, LiP and Lac enzyme activities were the variables with more weight on the second component. P. sajor caju revealed to be the only species able to perform the biological treatment without promoting an increment in the toxicity of the effluent to the Vibrio fischeri, as it was assessed by the Microtox assay. The opposite was recorded for the treatments with the other three species of fungus. EC(50-5 min) values ranging between 28 and 57% (effluent concentrations) were recorded even after 10 to 13 days of treatment with P. chrysosporium, R. oryzae or with T. versicolor.

Effects of diamond nanoparticle exposure on the internal structure and reproduction of Daphnia magna

Nanomaterials have significant technological advantages but their release into the environment also carry potential ecotoxicological risks. Carbon-based nanoparticles and particularly diamond nanoparticles have numerous industrial and medical applications. The aim of the present study was to evaluate the toxic effects of diamond nanoparticles with an average particle size of 20 nm on the survival, reproduction and tissue structure of the freshwater crustacean Daphnia magna. The chronic toxicity test results showed 100% mortality at concentrations higher than 12.5 mg l(-1) and that reproduction inhibition occurred in concentrations higher than 1.3 mg l(-1). Light microscopy showed that diamond nanoparticles adhere to the exoskeleton surface and accumulate within the gastrointestinal tract, suggesting that food absorption by the gut cells may be blocked. The results support the use of chronic approaches in environmental protection as part of an integrated environmental monitoring and assessment strategy.

Liver Alterations in Two Freshwater Fish Species ( Carassius auratus and Danio rerio ) Following Exposure to Different TiO 2 Nanoparticle Concentrations

The toxicity of titanium dioxide nanoparticles (TIO₂ NPs) and oxidative stress effects were studied in two freshwater fish species (Carassius auratus and Danio rerio) exposed for 21 days to different concentrations (0.01, 0.1, 1, 10, 100/mgL) of TiO₂ NPs and to a control (tap water). Additional fish were transferred to clean water for 14 days to assess the ability to recover from exposure to TiO₂ NPs. Activities of the enzyme glutathione-S-transferase (GST) and lipid peroxidation (LPO) (malondialdheyde) were measured as indicators of oxidative stress. Histological and ultra-structural changes in livers from both species of fish were evaluated by light and electron microscopy. Results show a general GST activity increase according to TiO₂ NPs concentrations, which is in agreement with data from LPO. After 21 days, GST activities decreased possibly caused by suppression of GST synthesis as a result of severe stress. Histological and ultra-structural analysis of livers from exposed fish show degeneration of the hepatic tissue and alterations in hepatocytes such as glycogen depletion and an increase in lipofucsin lysosome-like granules. After a depuration period a partial recovery for biochemical markers and cells was observed. The results suggest that TiO₂ promotes alterations in hepatic tissues compatible with oxidative stress.

Continuous Time Simulation and Discretized Models for Cost-Effectiveness Analysis

The design of decision-analytic models for cost-effectiveness analysis has been the subject of discussion. The current work addresses this issue by noting that, when time is to be explicitly modelled, we need to represent phenomena occurring in continuous time. Models evaluated in continuous time may not have closed-form solutions, and in this case, two approximations can be used: simulation models in continuous time and discretized models at the aggregate level.Stylized examples were set up where both approximations could be implemented. These aimed to illustrate determinants of the use of the two approximations: cycle length and precision, the use of continuity corrections in discretized models and the discretization of rates into probabilities. The examples were also used to explore the impact of the approximations not only in terms of absolute survival but also cost effectiveness and incremental comparisons.Discretized models better approximate continuous time results if lower cycle lengths are used. Continuous time simulation models are inherently stochastic, and the precision of the results is determined by the simulation sample size. The use of continuity corrections in discretized models allows the use of greater cycle lengths, producing no significant bias from the discretization. How the process is discretized (the conversion of rates into probabilities) is key. Results show that appropriate discretization coupled with the use of a continuity correction produces results unbiased for higher cycle lengths. Alternative methods of discretization are less efficient, i.e. lower cycle lengths are needed to obtain unbiased results.The developed work showed the importance of acknowledging bias in estimating cost effectiveness. When the alternative approximations can be applied, we argue that it is preferable to implement a cohort discretized model rather than a simulation model in continuous time. In practice, however, it may not be possible to represent the decision problem by any conventionally defined discretized model, in which case other model designs need to be applied, e.g. a simulation model.

A multi-integrated approach on toxicity effects of engineered TiO2 nanoparticles

The new properties of engineered nanoparticles drive the need for new knowledge on the safety, fate, behavior and biologic effects of these particles on organisms and ecosystems. Titanium dioxide nanoparticles have been used extensively for a wide range of applications, e.g, self-cleaning surface coatings, solar cells, water treatment agents, topical sunscreens. Within this scenario increased environmental exposure can be expected but data on the ecotoxicological evaluation of nanoparticles are still scarce. The main purpose of this work was the evaluation of effects of TiO2 nanoparticles in several organisms, covering different trophic levels, using a battery of aquatic assays. Using fish as a vertebrate model organism tissue histological and ultrastructural observations and the stress enzyme activity were also studied. TiO2 nanoparticles (Aeroxide® P25), two phase composition of anatase (65%) and rutile (35%) with an average particle size value of 27.6±11 nm were used. Results on the EC50 for the tested aquatic organisms showed toxicity for the bacteria, the algae and the crustacean, being the algae the most sensitive tested organism. The aquatic plant Lemna minor showed no effect on growth. The fish Carassius auratus showed no effect on a 21 day survival test, though at a biochemical level the cytosolic Glutathione-S-Transferase total activity, in intestines, showed a general significant decrease (p<0.05) after 14 days of exposure for all tested concentrations. The presence of TiO2 nanoparticles aggregates were observed in the intestine lumen but their internalization by intestine cells could not be confirmed.

Impact of a secondary treated bleached Kraft pulp mill effluent in both sexes of goldfish (Carassius auratus L.)

The aim of the present study was to assess the toxic effects of a secondary treated effluent from a modern pulp mill processing Eucalyptus globulus on both sexes of goldfish. The effects in the exposed fish were investigated by measuring biomarkers which have been used to assess the effects of BKME on aquatic biota, with particular emphasis in fish. However, few studies have been focused on effluents from pulp mill plants processing eucalyptus. The relative proportion of cytochrome P450 (CYP1A) and vitellogenin (VTG) induction were analyzed in the livers of males and females goldfish, exposed to different concentrations of a bleached Kraft pulp mill (BKPM) effluent. Somatic indices such as HSI (hepatosomatic index) and GSI (gonadosomatic index) were calculated and a significant reduction was found in males GSI. A significant increase of HSI was recorded for both sexes exposed to 50% BKPM effluent. Exposure to BKPM effluent induced CYP1A synthesis in both sexes and decreased VTG synthesis in females according to the different effluent concentrations suggesting that the secondary treated effluent contained compounds that affect fish negatively. The results suggest that BKPM effluent can cause sex-related biochemical changes in xenobiotic metabolism.

Sea warming affects bream (Sparus aurata) tissues and stress proteins (HSP70)

***** and M.S. Diniz* *REQUIMTE, Departamento de Quimica, Faculdade de Ciencias e Tecnologia, Centro de Quimica Fina e Biotecnologia, Universidade Nova de Lisboa, 2829-516 Caparica. **Laboratorio Maritimo da Guia, Centro de Oceanografia, Faculdade de Ciencias da Universidade de Lisboa, Av. Nossa Senhora do Cabo, 939, 2750-374 Cascais, Portugal ***Centro de Oceanografia, Faculdade de Ciencias, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal ****IMAR-Instituto do Mar, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa -Departamento de Ciencias e Engenharia do Ambiente. Quinta da Torre, 2829-516 Caparica, Portugal. *****BIOSCOPE Group, Physical-Chemistry Department, Faculty of Science, Campus Ourense, University of Vigo, 32004, Ourense, Spain. ******Unitat d´Enginyeria de Proteines i Proteomica, Institut de Biotecnologia i Biomedicina, Universitat Autonoma de 08193, Barcelona, Spain The increase in CO

Extremal Behavior of the Generalized Integer-Valued Random Coefficient Autoregressive Process

A stationary generalized random coefficient integer auto-regressive model of order 1 (Generalized RCINAR(1)), based on a thinning random operation, is presented. It is proved that the process satisfies a long-range condition as well as a local dependence condition, which are appropriate extensions of the well-known D(u n ) and D′(u n ) conditions of Leadbetter. Assuming that the marginal discrete distribution function belongs to Anderson’s class, and then it does not belong to the domain of attraction of any max-stable distribution, the limit in distribution of the maximum of k n random variables, being {k n } a geometric growing sequence, is obtained. This limit is a discrete max-semistable distribution function usually called discretized Gumbel.

Histological and biochemical effects of exposure to TiO 2 nanoparticles in livers of two freshwater fish species: Carassius auratus and Danio rerio

1REQUIMTE, Departamento de Quimica, Faculdade de Ciencias e Tecnologia, Centro de Quimica Fina e Biotecnologia, Universidade Nova de Lisboa, 2829-516 Caparica. 2Anatomia Patologica, Centro Hospitalar de Lisboa Central Hospital Curry Cabral, Rua da Beneficencia 8, 1069-166 Lisboa, Portugal, and Centro de Estudos do Ambiente e do Mar (CESAM/FCUL) – Faculdade de Ciencias da Universidade de Lisboa, Campo Grande, 1749-016, Lisboa, Portugal 3IMAR-Instituto do Mar, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa -Departamento de Ciencias e Engenharia do Ambiente. Quinta da Torre, 2829-516 Caparica, Portugal. 4LNEG, Estrada do Paco do Lumiar 22, 1649-038 Lisboa, Portugal *mesd@fct.unl.pt

Reliability Control of Complex Systems through Penultimate Approximations.

Abstract In statistical quality management, the control of the reliability of a system is a topic of primordial relevance in manufacture industry. After a brief reference to the importance of order statistics in reliability, the fact that any coherent system can be represented as either a series-parallel (SP) or a parallel-series (PS) system is referred. The lifetime of such a system can thus be written as the minimum of maxima or the maximum of minima, which reveals the relevant role of extreme value theory (EVT) in the field of reliability. Indeed, for large-scale coherent systems can be sensible to assume that the number of system components goes to infinity. And then, the possible non-degenerate extreme value distributions either for maxima or for minima are eligible candidates for the system reliability or at least for the finding of adequate lower and upper bounds for such a reliability. The main limiting results in EVT will be briefly mentioned, and the identification of the possible ultimate limit laws for maxima of a min-stable distribution and for minima of a max-stable distribution are identified. Considering a fixed large number of components, pre-asymptotic or penultimate models can lead to an improvement of the convergence rate and are provided. On the basis of a small-scale Monte-Carlo simulation study, we further make clear the attained gain in accuracy when a penultimate approximation is used instead of the ultimate limiting approximation.