Avaliação da exposição de crianças a material particulado em suspensão

Este trabalho teve como principal objectivo caracterizar a exposição de crianças a partículas atmosféricas e aos elementos químicos que as constituem. Pretendeu-se também determinar as fontes e processos que afectam os níveis e composição das partículas em suspensão no ar ambiente e no interior de salas de aula de escolas do 1º ciclo localizadas no centro de Lisboa. Os efeitos das partículas atmosféricas na saúde humana manifestam-se sobretudo ao nível do aparelho respiratório, dependendo da sua composição química, e principalmente da sua dimensão. As partículas inaláveis (PM10) podem depositar-se nas unidades funcionais do sistema respiratório. O PM2,5 podem atingir os alvéolos pulmonares e penetrar no sistema circulatório. As crianças são um dos principais grupos de risco, visto que os seus órgãos e tecidos ainda estão em desenvolvimento, ficando mais susceptíveis à exposição de partículas. A recolha de material particulado foi realizada no ar ambiente recorrendo a um colector PARTISOL e no interior e exterior das escolas usando amostradores GENT. A concentração total de partículas em suspensão foi determinada por gravimetria. A caracterização química da matéria particulada foi efectuada por Análise por Activação com Neutrões (INAA) para a determinação da concentração dos elementos e por Cromatografia Iónica para a quantificação de iões solúveis em água. Em 2007, a concentração média anual de PM2,5 no Centro de Lisboa foi de 18µg/m3. Através da Análise de Componentes Principais e Regressão Multilinear verificou-se que a massa das partículas da fracção fina resulta essencialmente da produção de aerossóis secundários (35%) de uma fonte de cálcio (28%) e da emissão de poluentes por veículos motorizados (23%). No interior das escolas verificou-se que as concentrações de partículas são mais elevadas comparativamente com o ambiente exterior, principalmente no PM2,5-10 (74µg/m3). A ressuspensão de partículas causada pelas actividades desempenhadas no interior das salas e a suspensão de poeiras do solo transportada pelas crianças, são as principais causas apontadas. O Ca é o elemento maioritário no interior das escolas. Os resultados obtidos neste trabalho não excederam os limites estabelecidos pela Legislação Portuguesa.

Neutron activation analysis of wheat samples

The deficiency of essential micronutrients and excess of toxic metals in cereals, an important food items for human nutrition, can cause public health risk. Therefore, before their consumption and adoption of soil supplementation, concentrations of essential micronutrients and metals in cereals should be monitored. This study collected soil and two varieties of wheat samples–Triticum aestivum L. (Jordão/bread wheat), and Triticum durum L. (Marialva/durum wheat) from Elvas area, Portugal and analyzed concentrations of As, Cr, Co, Fe, K, Na, Rb and Zn using Instrumental Neutron Activation Analysis (INAA) to focus on the risk of adverse public health issues. The low variability and moderate concentrations of metals in soils indicated a lower significant effect of environmental input on metal concentrations in agricultural soils. The Cr and Fe concentrations in soils that ranged from 93–117 and 26,400–31,300 mg/kg, respectively, were relatively high, but Zn concentration was very low (below detection limit <22 mg/kg) indicating that soils should be supplemented with Zn during cultivation. The concentrations of metals in roots and straw of both varieties of wheat decreased in the order of K>Fe>Na>Zn>Cr>Rb>As>Co. Concentrations of As, Co and Cr in root, straw and spike of both varieties were higher than the permissible limits with exception of a few samples. The concentrations of Zn in root, straw and spike were relatively low (4–30 mg/kg) indicating the deficiency of an essential micronutrient Zn in wheat cultivated in Portugal. The elemental transfer from soil to plant decreases with increasing growth of the plant. The concentrations of various metals in different parts of wheat followed the order: Root>Straw>Spike. A few root, straw and spike samples showed enrichment of metals, but the majority of the samples showed no enrichment. Potassium is enriched in all samples of root, straw and spike for both varieties of wheat. Relatively to the seed used for cultivation, Jordão presented higher transfer coefficients than Marialva, in particular for Co, Fe, and Na. The Jordão and Marialva cultivars accumulated not statistically significant different concentrations of different metals. The advantages of using INAA are the multielementality, low detection limits and use of solid samples (no need of digestion).

Síntese e fotosensibilização de nanotubos de titanatos

Nesta tese é descrita a preparação de nanotubos de titanatos (TNT) via síntese hidrotérmica alcalina, usando uma nova metodologia que evita a utilização de TiO2 cristalino como precursor. Foi estudada a influência da substituição sódio/protão na estrutura, morfologia e propriedades ópticas dos materiais preparados. Os resultados mostraram que a substituição Na+ → H+ resulta numa redução na distância intercamadas dos TNTs, tendo sido medidos valores entre 1.13±0.03 nm e 0.70±0.02 nm para aquele parâmetro. O comportamento óptico dos TNTs foi estudado na região UV-vis, estimando-se um hiato óptico de energia 3.27±0.03 eV para a amostra com maior teor de sódio enquanto que para a amostra protonada foi determinado um valor de 2.81±0.02 eV. Estes valores mostram que a troca iónica Na+ → H+ teve influência no desvio da banda de absorção dos TNTs para a região do visível próximo. A actividade fotocatalítica dos TNTs na degradação do corante rodamina 6G (R6G) foi posteriormente estudada. Verificou-se que, apesar de a amostra com maior teor de sódio ter sido a que exibiu maior capacidade para adsorver o R6G, foi a amostra protonada que apresentou a actividade catalítica mais elevada na fotodegradação deste corante. Numa segunda fase, e com o objectivo de preparar novos materiais nanoestruturados fotosensíveis, procedeu-se à decoração dos TNTs protonados com semicondutores (SC) nanocristalinos usando um método novo. Para o efeito os TNTs foram decorados com nanocristalites de ZnS, CdS e Bi2S3. Foi estudada a influência do tipo de semicondutor na estrutura, morfologia e propriedades ópticas dos SC/TNTs obtidos. Verificou-se que, para qualquer dos semicondutores usados no processo de decoração, a estrutura dos TNTs é preservada e não ocorre segregação do SC. Verificou-se ainda que a morfologia dos nanocompósitos preparados depende fortemente da natureza do semicondutor. No que respeita ao comportamento óptico destes materiais, foram determinados hiatos ópticos de energia 3.67±0.03 eV, 2.47±0.03 eV e 1.35±0.01 eV para as amostras ZnS/TNT, CdS/TNT e Bi2S3/TNT, respectivamente. Estes resultados mostram que através do processo de decoração de TNTs com semicondutores podem ser preparados materiais nanocompósitos inovadores, com propriedades ópticas novas e/ou pré-definidas numa gama alargada do espectro electromagnético.

Survey of cyclopids (Crustacea, Copepoda) in Brazil and preliminary screening of their potential as dengue vector predators

INTRODUCTION: Cyclopid copepods are known to be good mosquito controllers, specially as regards the larvae of the dengue vectors Aedes aegypti and Ae. albopictus. MATERIAL AND METHOD: The objective of the study was to survey the local copepod fauna and search for new strains of M. longisetus var. longisetus, comparing the potential of the samples found with the current strain ML-01 against Ae. albopictus larvae, under laboratory conditions. Eleven bodies of water in Campinas, SP, Brazil, were screened for copepods by collecting 1.5 l of water from each of then. The predatory potential of adults copepods was evaluated over 24 h, in the laboratory, for groups of 5 individuals preying upon 30 first instar Ae. albopictus larvae. RESULTS AND CONCLUSION: The following cyclopid species were found: Metacyclops mendocinus, Tropocyclops prasinus, Eucyclops sp, Eucyclops serrulatus, Eucyclops solitarius, Eucyclops ensifer, Macrocyclops albidus var. albidus and Mesocyclops longisetus var. longisetus. The predatory potential of these copepods ranged from nil to 97.3%. A sample collected in the field containing only M. longisetus var. longisetus showed the best control efficiency with no significant difference from a three-year old laboratory culture (ML-01) of the same species evaluated for comparison. The sample with few M. albidus var. albidus was ranked in second place showing an average 25.9% efficiency. The use of copepods in trap tires as dengue vector controllers is discussed.

Patterns of induced abortion in urban area of Southeastern region, Brazil

OBJECTIVE: To assess the behavior of induced abortion as a function of certain demographic variables, for the population of fertile women (15 to 49 years old) residing in the Vila Madalena subdistrict S. Paulo (Brazil). MATERIAL AND METHOD: Two population samples were selected. One sample, with 996 women, investigated the incidence of induced abortions during 1987, using the RRT. In the other, involving 1,004 women, the same information was detected through a conventional approach. In both samples, the induced abortion occurring during the reproductive life was recorded in direct fashion. Though this analysis refers only to information about past abortions, that is by 2,000 women -, it should be noted that it is exactly the RRT that lends credibility to the found or results given results. CONCLUSION: The analysis furnishes evidence showing that single women, young women between the ages of 15 and 19, women who have not had live births, women who have a number of children below the expected ideal, women who use contraceptive methods (especially inefficient ones) and women who do not have any restrictions as to abortion constitute the categories most inclined to resort to induced abortion. This grouping suggests the existence of interrelationships between categories, that is, each of these categories is probably composed primarily of the same women, those who are at the beginning of their reproductive lives.

Accessing Planktothrix species diversity and associated toxins using quantitative real-time PCR in natural waters

Tese de Doutoramento em Biologia apresentada à Faculdade de Ciências da Universidade do Porto, 2015.

Cr2O3 thin films grown at room temperature by low pressure laser chemical vapour deposition

Chromia (Cr2O3) has been extensively explored for the purpose of developing widespread industrial applications, owing to the convergence of a variety of mechanical, physical and chemical properties in one single oxide material. Various methods have been used for large area synthesis of Cr2O3 films. However, for selective area growth and growth on thermally sensitive materials, laser-assisted chemical vapour deposition (LCVD) can be applied advantageously. Here we report on the growth of single layers of pure Cr2O3 onto sapphire substrates at room temperature by low pressure photolytic LCVD, using UV laser radiation and Cr(CO)(6) as chromium precursor. The feasibility of the LCVD technique to access selective area deposition of chromia thin films is demonstrated. Best results were obtained for a laser fluence of 120 mJ cm(-2) and a partial pressure ratio of O-2 to Cr(CO)(6) of 1.0. Samples grown with these experimental parameters are polycrystalline and their microstructure is characterised by a high density of particles whose size follows a lognormal distribution. Deposition rates of 0.1 nm s(-1) and mean particle sizes of 1.85 mu m were measured for these films. (C) 2011 Elsevier B.V. All rights reserved.

Higienização de utensílios alimentares em estabelecimentos de ensino pré-escolar: um estudo em duas instituições de ensino

A transmissão de microrganismos patogénicos pode ocorrer através da sua presença em resíduos de alimentos ou água depositados sobre os utensílios que se encontram em deficientes condições de higienização. Para que seja assegurada a higiene alimentar torna-se essencial a conservação e higienização dos utensílios, desempenhando os manipuladores de alimentos um papel determinante no que diz respeito à execução de um eficaz protocolo de higienização, uma correcta manipulação e a adopção de normas higiénicas que evitem a contaminação dos utensílios. Da totalidade das amostras realizadas aos utensílios alimentares provenientes das duas instituições de ensino pré-escolar analisados neste estudo, 27% encontravam-se contaminadas e num insuficiente estado de higienização devido à presença de microrganismos mesófilos aeróbios a 30ºC em número superior a 100 UFC/peça. Foi verificado a presença de fungos e a pesquisa positiva de enterobactérias e bactérias presumíveis de E. coli. Em ambos os estabelecimentos de ensino, os utensílios constituídos por material plástico apresentaram níveis de contaminação na generalidade superiores em relação aos constituídos por aço inoxidável. O tipo de material e o estado dos utensílios são também aspectos relevantes que podem influenciar o processo de adesão microbiana e consequente formação de biofilme, pelo que na aquisição dos utensílios devem ser consideradas as características inerentes aos diferentes materiais, devendo os mesmos ser substituídos periodicamente devido ao desgaste causado pelo seu frequente uso. Para além disso, os utensílios devem passar constantemente por uma avaliação microbiológica para controlo da eficiência do processo de higienização, contribuindo para a garantia da higiene alimentar e segurança do alimento. A garantia da higiene alimentar constitui uma base importante em idades de maior vulnerabilidade.

Desilication of MOR zeolite: Conventional versus microwave assisted heating

MOR zeolites were modified via desilication treatments with NaOH, under conventional and microwave heating. The samples were characterized by powder X-ray diffraction, (27)Al and (29)Si NMR spectroscopy. TEM and N(2) adsorption at -196 degrees C. The acidity of the samples and the space available inside the pores were evaluated through a catalytic model reaction, the isomerization of m-xylene, for which the profiles of the coke thermal decomposition were also analyzed. Powder X-ray diffraction and (29)Si and (27)Al MNR results show that in comparison with conventional heating, microwave irradiation (a less time consuming process) leads to identical amount of Si extraction from the zeolite framework. With this treatment. in addition to the customary mesopores development promoted by conventional heating, a partial conversion of the zeolite microporosity into larger micropores, is observed. The microwave irradiated and conventionally heated samples show different catalytic behavior in the m-xylene isomerization model reaction. It was observed that, by controlling the experimental conditions, it is possible to obtain samples with catalytic properties closer to the parent material, which is also confirmed by the respective coke analysis. (C) 2011 Elsevier B.V. All rights reserved.

Multilayer Architectures Based on a-SiC:H Material: Tunable Wavelength Filters in Optical Processing Devices

The characteristics of tunable wavelength filters based on a-SiC:H multilayered stacked pin cells are studied both theoretically and experimentally. The optical transducers were produced by PECVD and tested for a proper fine tuning of the cyan and yellow fluorescent proteins emission. The active device consists of a p-i'(a-SiC:H)-n/p-i(a-Si:H)-n heterostructures sandwiched between two transparent contacts. Experimental data on spectral response analysis, current-voltage characteristics and color and transmission rate discrimination are reported. Cyan and yellow fluorescent input channels were transmitted together, each one with a specific transmission rate and different intensities. The multiplexed optical signal was analyzed by reading out, under positive and negative applied voltages, the generated photocurrents. Results show that the optimized optical transducer has the capability of combining the transient fluorescent signals onto a single output signal without losing any specificity (color and intensity). It acts as a voltage controlled optical filter: when the applied voltages are chosen appropriately the transducer can select separately the cyan and yellow channel emissions (wavelength and frequency) and also to quantify their relative intensities. A theoretical analysis supported by a numerical simulation is presented.

Juntas mecânicas em material compósito

O âmbito da presente tese é o estudo de juntas mecânicas em material compósito realizado com fibra de vidro. Os materiais compósitos são a solução procurada pela generalidade dos sectores da indústria, devido essencialmente à sua grande capacidade estrutural e à sua resistência mecânica específica, ou seja, a resistência mecânica versus peso ser em geral maior que nas ligações metálicas. O estudo efectuado neste trabalho é referente à delaminação presente na furação de materiais compósitos, sendo esta um dos problemas de maior gravidade, existente quando se realiza a furação do material. Este problema influência a integridade estrutural do material bem como a sua fiabilidade a longo prazo. Foram usados dois métodos de furação, o primeiro conhecido por furação convencional e o segundo habitualmente designado método KTH ou por furação orbital. Foi feita uma comparação entre estes dois métodos e verificado qual deles apresenta menor delaminação em torno do furo e melhor qualidade de furo. Conclui-se que a furação orbital apresenta uma delaminação inferior relativamente à furação convencional, e que esta é preferível para a realização de furação em material compósito.

Novel method using a laser scanning cytometer for detection of Mycobacteria in clinical samples

In order to evaluate the capacity of laser scanning cytometry (LSC) to detect acid-fast bacilli directly on clinical samples, a comparison between Kinyoun-stained smears analyzed under light microscopy and propidium iodide-auramine-stained smears analyzed by LSC was performed. The results were compared with those for culture on BACTEC MGIT 960. LSC is a new, reliable methodology to detect Mycobacteria.

Arrow Plot: a new graphical tool for selecting up and down regulated genes and genes differentially expressed on samples subgroups

Background: A common task in analyzing microarray data is to determine which genes are differentially expressed across two (or more) kind of tissue samples or samples submitted under experimental conditions. Several statistical methods have been proposed to accomplish this goal, generally based on measures of distance between classes. It is well known that biological samples are heterogeneous because of factors such as molecular subtypes or genetic background that are often unknown to the experimenter. For instance, in experiments which involve molecular classification of tumors it is important to identify significant subtypes of cancer. Bimodal or multimodal distributions often reflect the presence of subsamples mixtures. Consequently, there can be genes differentially expressed on sample subgroups which are missed if usual statistical approaches are used. In this paper we propose a new graphical tool which not only identifies genes with up and down regulations, but also genes with differential expression in different subclasses, that are usually missed if current statistical methods are used. This tool is based on two measures of distance between samples, namely the overlapping coefficient (OVL) between two densities and the area under the receiver operating characteristic (ROC) curve. The methodology proposed here was implemented in the open-source R software. Results: This method was applied to a publicly available dataset, as well as to a simulated dataset. We compared our results with the ones obtained using some of the standard methods for detecting differentially expressed genes, namely Welch t-statistic, fold change (FC), rank products (RP), average difference (AD), weighted average difference (WAD), moderated t-statistic (modT), intensity-based moderated t-statistic (ibmT), significance analysis of microarrays (samT) and area under the ROC curve (AUC). On both datasets all differentially expressed genes with bimodal or multimodal distributions were not selected by all standard selection procedures. We also compared our results with (i) area between ROC curve and rising area (ABCR) and (ii) the test for not proper ROC curves (TNRC). We found our methodology more comprehensive, because it detects both bimodal and multimodal distributions and different variances can be considered on both samples. Another advantage of our method is that we can analyze graphically the behavior of different kinds of differentially expressed genes. Conclusion: Our results indicate that the arrow plot represents a new flexible and useful tool for the analysis of gene expression profiles from microarrays.

Historical Heritage: A Study to Conservation

Considering ancient monuments and historical buildings, it seems that these mortars have proved to be durable and reliable materials. The restoration and maintenance of old renders is one of the key aspects of correct rehabilitation practice. The ideal course of action is to replace the damaged material by a material with compatible characteristics.The study in development presents the chemical, physical and morphologic analysis performed for ancient air lime mortars belonging to historical monuments: Santa Marta Fortress in the coast line Lisbon-Cascais dated from XVII century and Defense Wall of Lisbon dated from XI century, which layout could be associated to roman period. It is important to underline that the studied samples of ancient portuguese air lime mortars, have been submitted during centuries to very severe maritime environment that includes daily cycles of wet/dry, wind, friction and the constant presence of salts, generally aggressive. However, they show very good performance and conservation state, unlike most of the new air lime mortars, which are generally considered weak, not very durable, materials. This work is included in a study intending to determine key factors to the durability of these ancient materials in presence of water. Visible reaction rims around some aggregates suggests the occurrence of pozzolanic reactions between aggregates and the lime binder that creates neoformation products, such as calcium-silico-aluminates, which seems be, besides the pores filling, the responsible for the resistance and cohesion of these ancient mortars submitted to aggressive humid environments.

Extraction of ochratoxin A in bread samples by the QuEChERS methodology

A QuEChERS method for the extraction of ochratoxin A (OTA) from bread samples was evaluated. A factorial design (23) was used to find the optimal QuEChERS parameters (extraction time, extraction solvent volume and sample mass). Extracts were analysed by LC with fluorescence detection. The optimal extraction conditions were: 5 g of sample, 15 mL of acetonitrile and 3 min of agitation. The extraction procedure was validated by systematic recovery experiments at three levels. The recoveries obtained ranged from 94.8% (at 1.0 μg kg -1) to 96.6% (at 3.0 μg kg -1). The limit of quantification of the method was 0.05 μg kg -1. The optimised procedure was applied to 20 samples of different bread types (‘‘Carcaça’’, ‘‘Broa de Milho’’, and ‘‘Broa de Avintes’’) highly consumed in Portugal. None of the samples exceeded the established European legal limit of 3 μg kg -1.