Viabilidade econômica de arroz convencional vs. híbrido.

O presente trabalho buscou elaborar um instrumento de fácil utilização para comparar os ganhos marginais de se trocar variedades convencionais de arroz por híbridos, em diferentes situações, por meio de orçamentação parcial

Development of cellulose acetate membranes containing nanoparticles for water applications

The growth of human population and inherent activities, the improper industrialization practices, the direct addition of materials TO the waterway, and the excessive use of fertilizers containing phosphates to increase the production of crops are the main sources for the high input of phosphates in water bodies. These effects have been causing eutrophication, and bacterial contamination of the water. In fact, the bacteria present in the water can cause harmful disease, sickness or other problems to the human being. Moreover, the excess of phosphates in the aquatic system induces excessive growth of plants, which consume oxygen of the water body, thereby creating the state of hypoxia, which causes a reduction in specific fish and other animals. Therefore, the removal of phosphates from eutrophic waters and bacteria are crucial to avoid health problems, especially near urban areas[1]. The most common way to purify water is through membrane separation processes, in fact, cellulose acetate (CA) membranes have been used for reverse osmosis membranes [2] for converting impaired water into fresh-water. However, several components can be incorporated into cellulose structure to allow the development of membranes for different applications[3]. The present work aims to develop a hybrid membrane based on CA with embedded silver and/or aluminium nanoparticles, for the remediation of contaminated aquatic environments with microorganism, which can also be used for removal of water contaminated with phosphate ion. Therefore, CA membranes were obtained by solution casting, where silver and/or aluminium nanoparticles were chemical reduced in-situ. Silver nanoparticles (Ag-NPs) were synthesized using silver nitrate and sodium borohydride as reducing agent. Otherwise, aluminium nanoparticles (Al-NPs) were obtained using aluminium isopropoxide as the starting precursor in the presence of acid. The detection of Al-NPs in the membranes was carried out by FTIR spectra analysis, which showed that Al-O bonds were formed between the aluminium precursor and the CA. The study of phosphorus adsorption kinetics in membranes with embedded Al-NPs were proven to be efficient for the removal of phosphorus. This membrane showed considerable ability to remove phosphate ions from aqueous solutions at low aluminium nanoparticle content into the CA/Ag-NPs matrices. In-situ the developed membranes showed good antimicrobial behaviour preventing the growth of microorganisms. The results indicate that the synthesized CA/Ag-NPs/Al-NPs membranes could have potential to be used in the remediation of water resources

Transmissão de preços de arroz no mercado internacional e nacional.

Este estudo pretende analisar a formação dos preços de arroz e de que forma os mercados produtores se relacionam em relação aos preços, ou seja, há um mercado dominante e seguidores na formação dos preços? Há transmissão de preços entre os mercados produtores do arroz irrigado no país e de que forma os preços internacionais afetam o comportamento dos preços internos

Desenvolvimento de membranas de acetato de celulose contendo nanopartículas de prata-alumínio

Dissertação de mestrado integrado em Engenharia de PolímerosO objetivo da presente dissertação consiste em desenvolver e avaliar o potencial de uma membrana biopolimérica de acetato de celulose (AC), contendo nanopartículas de prata (Ag-NPs) e/ou alumínio (Al-NPs) no tratamento e remediação de meios aquáticos. Para esse efeito, foram sintetizadas membranas de AC contendo Ag-NPs e/ou Al-NPs através do método de evaporação do solvente, obtendo-se Ag-NPs por redução química do nitrato de prata (AgNO3) com o agente redutor, borohidreto de sódio (NaBH4). As Al-NPs foram obtidas por síntese in situ de um precursor à base de alumínio, o isopropóxido de alumínio (Al(Pr-i-O)3) na presença de ácido clorídrico (HCl). Investigou-se ainda o efeito da estabilização das Ag-NPs através da incorporação de um surfactante, o poloxamer 407 (P407). As membranas de AC contendo Ag-NPs com e sem a presença do P407 foram caracterizadas através de ensaios de microscopia eletrónica de varrimento (SEM), espectroscopia dispersiva de raios-X (EDS), dispersão de luz dinâmica (DLS), espectroscopia de infravermelho por transformada de Fourier (FTIR), análise termogravimétrica (TGA), espectroscopia UV-Visível, análise dinâmico-mecânica (DMA) e medição de ângulos de contacto, assim como através de estudos da atividade antibacteriana. Como o principal objetivo desta dissertação consiste no desenvolvimento de uma membrana de nanocompósito para duas possíveis aplicações no tratamento de água contaminadas, inibir/remover microrganismos e o ião fosfato, foram realizados estudos da atividade antibacteriana, assim como estudos cinéticos de adsorção de fósforo. Da caracterização das membranas obtidas conclui-se que a incorporação de Ag-NPs na matriz de AC induziu uma melhoria das propriedades térmicas e mecânicas relativamente às de AC puro. Enquanto, a incorporação de P407 introduziu modificações superficiais na matriz de AC tornando-a mais hidrofílica. Resultados obtidos no estudo cinético de adsorção de fósforo nas membranas contendo Ag-NPs e Al-NPs confirmaram a eficiência destas membranas na remoção do fósforo. Relativamente ao carácter antibacteriano destas, este foi comprovado in situ, no qual se verificou o efeito bactericida nos testes realizados em águas com bactérias em suspensão.The aim of this dissertation is to develop and evaluate the potential of a biopolymeric membrane of cellulose acetate (CA), containing silver nanoparticles (Ag-NPs) and/or aluminum nanoparticles (Al-NPs) for the treatment and remediation of aquatic environments. For this purpose, CA membranes containing Ag-NPs and/or Al-NPs were synthesized by solvent casting, resulting in Ag-NPs obtained by chemical reduction of silver nitrate (AgNO3) with the reducing agent, sodium borohydride (NaBH4). The Al-NPs were obtained by in situ synthesis of an aluminum-based precursor, aluminum isopropoxide (Al(Pr-i-O)3) in the presence of hydrochloric acid (HCl). The stabilization effect of Ag-NPs through the incorporation of a surfactant, poloxamer 407 (P407), was also investigated. The CA membranes containing Ag-NPs with and without the presence of P407 were characterized by scanning electron microscopy (SEM), dispersive X-ray spectroscopy (EDS), dynamic light scattering (DLS), Fourier-transformed infrared spectroscopy (FTIR), thermogravimetry analysis (TGA), ultraviolet-visible absorption spectroscopy, dynamic mechanical analysis (DMA), and contact angle measurement, as well as antibacterial activity studies. Since the main objective of this dissertation is the development of a nanocomposite membrane for two possible applications for contaminated water treatment, able to inhibit/remove microorganisms and phosphate ion, antibacterial activity studies, as well as adsorption kinetics of phosphorus studies, were performed. The characterization of the obtained membranes show that the incorporation of Ag-NPs in the CA matrix induced an improvement of the thermal and mechanical properties of the pure CA. The incorporation of P407 introduced superficial changes in the CA matrix, making the membrane more hydrophilic. Results obtained from the adsorption kinetics of phosphorous studies confirmed the phosphorous removal effectiveness of the CA membranes containing Ag-NPs and Al-NPs. In situ CA membranes containing Ag-NPs and Al-NPs antimicrobial behavior was proved, which revealed the bactericidal effect in the performed tests against suspended bacteria in water

Predictive equations of pulmonar function for healthy children in Portugal

[resumo][abstract

Synergistic activity of a novel class of azoimidazole dyes with polyvinylpyrrolidone-silver nanoparticles for the development of antibacterial textiles

The high demand for novel antimicrobial textiles by the medical, health care, hygiene, sportswear, personal protective equipment, and filtration sectors promoted the growth of functional textiles. However, the efficacy of antimicrobial agents against different pathogens is a considerable challenge due to the distinctive mechanisms of action and resistance. The development of novel synergistic antimicrobial agents may offer numerous opportunities to enhance antimicrobial effectiveness, namely boost the activity of individual agents, reduce dosages, minimize toxicity, and amplify the activity spectrum. On the one hand, azo dyes containing a heterocycle present good tinctorial strength and brightness of shades. In particular, the imidazole ring also has interesting antimicrobial, analgesic, and anti-inflammatory properties. On the other hand, silver nanoparticles (AgNPs) are renowned antimicrobial agents against a wide range of microorganisms, but their application is limited by the toxicity observed for effective concentrations. In this work, a novel class of azoimidazoles (AzoIz) and corresponding precursors (AmIz) were conjugated with polyvinylpyrrolidone-coated AgNPs, and their synergistic effect was assessed against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The results showed interesting antimicrobial properties of the novel AzoIz molecules when combined with a very small concentration of AgNPs. Thus, the application of these conjugates in textiles may lead to highly colored materials with remarkable antimicrobial properties, which worth to be further explored

Hydration status and water sources in 9-10 year soccer players

[resumo][abstract

Cholesteryl hemiazelate causes lysosome dysfunction impacting vascular smooth muscle cell homeostasis

In atherosclerotic lesions, vascular smooth muscle cells (VSMCs) represent half of the foam cell population, which is characterized by an aberrant accumulation of undigested lipids within lysosomes. Loss of lysosome function impacts VSMC homeostasis and disease progression. Understanding the molecular mechanisms underlying lysosome dysfunction in these cells is, therefore, crucial. We identify cholesteryl hemiazelate (ChA), a stable oxidation end-product of cholesteryl-polyunsaturated fatty acid esters, as an inducer of lysosome malfunction in VSMCs. ChA-treated VSMCs acquire a foam-cell-like phenotype, characterized by enlarged lysosomes full of ChA and neutral lipids. The lysosomes are perinuclear and exhibit degradative capacity and cargo exit defects. Lysosome luminal pH is also altered. Even though the transcriptional response machinery and autophagy are not activated by ChA, the addition of recombinant lysosomal acid lipase (LAL) is able to rescue lysosome dysfunction. ChA significantly affects VSMC proliferation and migration, impacting atherosclerosis. In summary, this work shows that ChA is sufficient to induce lysosomal dysfunction in VSMCs, that, in ChA-treated VSMCs, neither lysosome biogenesis nor autophagy are triggered, and, finally, that recombinant LAL can be a therapeutic approach for lysosomal dysfunction

Antimicrobial and antioxidant linen via laccase-assisted grafting

A laccase from Ascomycetemyceliophthora thermophila was used to assist the binding of chitosan and catechin onto a previous enzymatically oxidized linen surface. The process consists of the pre-treatment of the linen with laccase followed by the application of chitosan in a first step and catechin plus laccase in a second step. The results presented here support the conclusion that laccase is able to oxidize phenols naturally existing in flax fibres, and that the o-quinones formed promote the attachment of chitosan or/and catechin. The pre-treatment of linen with laccase is therefore the key factor for the success of catechin and chitosan grafting. A multifunctional linen product with both antioxidant and antibacterial properties was obtained with an acceptable level of durability in terms of end user requirements.Carla Silva would like to acknowledge the Portuguese Fundacao para a Ciencia e a Tecnologia (FCT) for funding under the scholarship SFRH/BPD/46515/2008