997 resultados para (H2S HS- S2-)
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Trabalho Final de Mestrado para obteno do grau de Mestre em Engenharia Mecnica
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A pi'n/pin a-SiC:H voltage and optical bias controlled device is presented and its behavior as image and color sensor, optical amplifier and demux device is discussed. The design and the light source properties are correlated with the sensor output characteristics. Different readout techniques are used. When a low power monochromatic scanner readout the generated carriers the transducer recognizes a color pattern projected on it acting as a direct color and image sensor. Scan speeds up to 10(4) lines per second are achieved without degradation in the resolution. If the photocurrent generated by different monochromatic pulsed channels is readout directly, the information is demultiplexed. Results show that it is possible to decode the information from three simultaneous color channels without bit errors at bit rates per channel higher than 4000 bps. Finally, when triggered by light of appropriated wavelength, it can amplify or suppress the generated photocurrent working as an optical amplifier (C) 2009 Published by Elsevier Ltd.
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Processes are a central entity in enterprise collaboration. Collaborative processes need to be executed and coordinated in a distributed Computational platform where computers are connected through heterogeneous networks and systems. Life cycle management of such collaborative processes requires a framework able to handle their diversity based on different computational and communication requirements. This paper proposes a rational for such framework, points out key requirements and proposes it strategy for a supporting technological infrastructure. Beyond the portability of collaborative process definitions among different technological bindings, a framework to handle different life cycle phases of those definitions is presented and discussed. (c) 2007 Elsevier Ltd. All rights reserved.
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Gene expression of three antioxidant enzymes, Mn superoxide dismutase (MnSOD), Cu,Zn superoxide dismutase (Cu,ZnSOD), and glutathione reductase (GR) was investigated in stationary phase Saccharomyces cerevisiae during menadione-induced oxidative stress. Both GR and Cu,ZnSOD mRNA steady state levels increased, reaching a plateau at about 90 min exposure to menadione. GR mRNA induction was higher than that of Cu,ZnSOD (about 14-fold and 9-fold after 90 min, respectively). A different pattern of response was obtained for MnSOD mRNA, with a peak at about 15 min (about 8-fold higher) followed by a decrease to a plateau approximately 4-fold higher than the control value. However, these increased mRNA levels did not result in increased protein levels and activities of these enzymes. Furthermore, exposure to menadione decreased MnSOD activity to half its value, indicating that the enzyme is partially inactivated due to oxidative damage. Cu,ZnSOD protein levels were increased 2-fold, but MnSOD protein levels were unchanged after exposure to menadione in the presence of the proteolysis inhibitor phenylmethylsulfonyl fluoride. These results indicate that the rates of Cu,ZnSOD synthesis and proteolysis are increased, while the rates of MnSOD synthesis and proteolysis are unchanged by exposure to menadione. Also, the translational efficiency for both enzymes is probably decreased, since increases in protein levels when proteolysis is inhibited do not reflect the increases in mRNA levels. Our results indicate that oxidative stress modifies MnSOD, Cu,ZnSOD, and GR gene expression in a complex way, not only at the transcription level but also at the post-transcriptional, translational, and post-translational levels.
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Cellular polarity concerns the spatial asymmetric organization of cellular components and structures. Such organization is important not only for biological behavior at the individual cell level, but also for the 3D organization of tissues and organs in living organisms. Processes like cell migration and motility, asymmetric inheritance, and spatial organization of daughter cells in tissues are all dependent of cell polarity. Many of these processes are compromised during aging and cellular senescence. For example, permeability epithelium barriers are leakier during aging; elderly people have impaired vascular function and increased frequency of cancer, and asymmetrical inheritance is compromised in senescent cells, including stem cells. Here, we review the cellular regulation of polarity, as well as the signaling mechanisms and respective redox regulation of the pathways involved in defining cellular polarity. Emphasis will be put on the role of cytoskeleton and the AMP-activated protein kinase pathway. We also discuss how nutrients can affect polarity-dependent processes, both by direct exposure of the gastrointestinal epithelium to nutrients and by indirect effects elicited by the metabolism of nutrients, such as activation of antioxidant response and phase-II detoxification enzymes through the transcription factor nuclear factor (erythroid-derived 2)-like 2 (Nrf2). In summary, cellular polarity emerges as a key process whose redox deregulation is hypothesized to have a central role in aging and cellular senescence.
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The fatty acid profile of erythrocyte membranes has been considered a good biomarker for several pathologic situations. Dietary intake, digestion, absorption, metabolism, storage and exchange amongst compartments, greatly influence the fatty acids composition of different cells and tissues. Lipoprotein and hepatic lipases were also involved in fatty acid availability. In the present work we examined the correlations between fatty acid in Red Blood Cells (RBCs) membranes, the fatty acid desaturase and elongase activities, glycaemia, blood lipids, lipoproteins and apoproteins, and the endothelial lipase (EL) mass in plasma. Twenty one individuals were considered in the present study, with age >18 y. RBCs membranes were obtained and analysed for fatty acid composition by gas chromatography. The amount of fatty acids (as percentage) were analysed, and the ratios between fatty acid 16:1/16:0; 18:1/18:0; 18:0/16:0; 22:6 n-3/20:5 n-3 and 20:4 n-6/18:2 n-6 were calculated. Bivariate analysis (rs) and partial correlations were determined. SCD16 estimation activity correlated positively with BMI (rs=0.466, p=0.043) and triacylglycerols (TAG) (rs=0.483, p=0.026), and negatively with the ratio ApoA1/ApoB (rs=-0.566, p=0.007). Endothelial lipase (EL) correlated positively with the EPA/AA ratio in RBCs membranes (rs=0.524, p=0.045). After multi-adjustment for BMI, age, hs-CRP and dietary n3/n6 ratio, the correlations remained significant between EL and EPA/AA ratio. At the best of our knowledge this is the first report that correlated EL with the fatty acid profile of RBCs plasma membranes. The association found here can suggest that the enzyme may be involved in the bioavailability and distribution of n-3/n-6 fatty acids, suggesting a major role for EL in the pathophysiological mechanisms involving biomembranes fatty acids, such as in inflammatory response and eicosanoids metabolites pathways.
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O meio ambiente uma grande preocupao mundial existindo cada vez mais imposies legais no sentido de o proteger. Torna-se assim necessrio que as indstrias adoptem e desenvolvam processos alternativos mais limpos. A indstria de curtumes transforma a pele animal em couro, material resistente putrefaco e com estabilidade trmica suficiente para ser manufacturado nas indstrias do calado, estofos, vesturio e marroquinaria. A transformao referida efectuada atravs duma srie de processos entre os quais o caleiro, processo que visa depilar a pele e promover o relaxamento da estrutura fibrilar, tem um papel importante. O processo de caleiro produz um efluente bastante poluente. Tendo em conta esse facto, este trabalho teve como objectivo desenvolver processos de depilao de pele caprina sem destruio do plo, com vista reduo da quantidade de sulfureto e sulfidrato de sdio utilizada e da carga poluente do efluente. Alm disso, o processo permite a recuperao do plo e este pode ser reaproveitado como fertilizante orgnico, hidrolisado de queratina, compostagem, etc. Todo o trabalho foi realizado tomando por base um processo de caleiro padro utilizado industrialmente, alterando-o de forma a obter um processo de caleiro ptimo de depilao sem destruio do plo com e sem utilizao de enzimas. Numa primeira fase, desenvolveu-se um processo de depilao sem destruio do plo normalmente utilizado para a pele de bovino que foi adaptado com resultados positivos, designado de processo sem enzimas. Numa segunda fase, desenvolveu-se um processo enzimtico em que se utilizou uma protease (Erhavit DMC), uma lipase (Defat 50) e uma amilase (Mayzme SD-L); este processo deu bons resultados tal como o anterior. A reduo da quantidade de sulfureto de sdio foi de 33% e 53% para o processo sem enzimas e processo com enzimas, respectivamente, em relao ao processo padro. O efeito dos processos na carga poluente, escala piloto, comprova uma reduo de 37% nos SST, 37% nos SDT, 60% na CQO, 9% no S2- e 73% no Azoto para o processo sem enzimas e uma reduo de 93% nos SST, 63% nos SDT, 69% na CQO, 69% no S2- e 83% no Azoto para o processo com enzimas, quando comparados com o processo padro. . Uma anlise de custos, com incidncia apenas nos agentes qumicos utilizados, permitiu concluir a existncia de uma reduo de custos anuais de 30% para o processo com enzimas e de 13% para o processo sem enzimas, quando comparados com o processo padro. Como concluso, os processos desenvolvidos apresentam um grande potencial para serem explorados industrialmente.
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The regulatory mechanisms by which hydrogen peroxide (H2O2) modulates the activity of transcription factors in bacteria (OxyR and PerR), lower eukaryotes (Yap1, Maf1, Hsf1 and Msn2/4) and mammalian cells (AP-1, NRF2, CREB, HSF1, HIF-1, TP53, NF-B, NOTCH, SP1 and SCREB-1) are reviewed. The complexity of regulatory networks increases throughout the phylogenetic tree, reaching a high level of complexity in mammalians. Multiple H2O2 sensors and pathways are triggered converging in the regulation of transcription factors at several levels: (1) synthesis of the transcription factor by upregulating transcription or increasing both mRNA stability and translation; (ii) stability of the transcription factor by decreasing its association with the ubiquitin E3 ligase complex or by inhibiting this complex; (iii) cytoplasm-nuclear traffic by exposing/masking nuclear localization signals, or by releasing the transcription factor from partners or from membrane anchors; and, (iv) DNA binding and nuclear transactivation by modulating transcription factor affinity towards DNA, co-activators or repressors, and by targeting specific regions of chromatin to activate individual genes. We also discuss how H2O2 biological specificity results from diverse thiol protein sensors, with different reactivity of their sulfhydryl groups towards H2O2, being activated by different concentrations and times of exposure to H2O2. The specific regulation of local H2O2 concentrations is also crucial and results from H2O2 localized production and removal controlled by signals. Finally, we formulate equations to extract from typical experiments quantitative data concerning H2O2 reactivity with sensor molecules. Rate constants of 140 M-1s1 and 1.3 103 M-1s1 were estimated, respectively, for the reaction of H2O2 with KEAP1 and with an unknown target that mediates NRF2 protein synthesis. In conclusion, the multitude of H2O2 targets and mechanisms provides an opportunity for highly specific effects on gene regulation that depend on the cell type and on signals received from the cellular microenvironment.
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A procura de piscinas para a prtica de atividades desportivas, recreativas e/ou teraputicas tem sofrido um aumento gradual ao longo do tempo. No entanto, nas piscinas existem vrios perigos associados sua utilizao. Relativamente aos perigos qumicos, a utilizao de desinfetantes base de cloro, bromo ou compostos derivados vai, por um lado, inativar microrganismos patognicos mas, por outro, dar origem a subprodutos ao reagir com compostos orgnicos presentes na gua. Os trihalometanos so um exemplo de subprodutos que se podem formar e, entre os compostos principais, esto o clorofrmio (TCM), bromodiclorometano (BDCM), clorodibromometano (CDBM) e bromofrmio (TBM). Este trabalho teve como objetivo o desenvolvimento de uma metodologia analtica para a determinao de trihalometanos em gua e ar de piscinas e a sua aplicao a um conjunto de amostras. Para a anlise dos compostos, foi utilizada a microextrao em fase slida no espao de cabea (HS-SPME) com posterior quantificao dos compostos por cromatografia gasosa com detetor de captura eletrnica (GC-ECD). Foi realizada uma otimizao das condies de extrao dos compostos em estudo em amostras de gua, atravs da realizao de dois planeamentos experimentais. As condies timas so assim obtidas para uma temperatura de extrao de 45C, um tempo de extrao de 25 min e um tempo de dessoro de 5 min. Foram analisadas amostras de guas de piscina cedidas pelo Centro de Estudos de guas, sendo avaliada a aplicao da tcnica HS-SPME e o efeito de matriz. O modo como se manuseiam as solues que contm os compostos em estudo influencia os resultados devido ao facto destes serem bastante volteis. Concluiu-se tambm que existe efeito de matriz, logo a concentrao das amostras dever ser determinada atravs do mtodo de adio de padro. A caraterizao da gua de piscinas interiores permitiu conhecer a concentrao de trihalometanos (THMs). Foram obtidas concentraes de TCM entre 4,5 e 406,5 g/L sendo que apenas 4 das 27 amostras analisadas ultrapassam o valor limite imposto pelo Decreto-Lei n306/2007 (100 g/L) no que diz respeito a guas de consumo humano e que normalmente utilizado como valor indicativo para a qualidade das guas de piscina. Relativamente concentrao obtida no ar de uma piscina interior, foi detetada uma concentrao mdia de 224 g/m3 de TCM, valor muito abaixo dos 10000 g/m3 impostos pelo Decreto-lei n24/2012, como valor limite para exposio profissional a agentes qumicos.
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O Ensino Superior Politcnico deve aproveitar o Processo de Bolonha para assumir um papel de relevo na resposta s necessidades do mercado de trabalho, seja atravs da adequao dos planos curriculares das suas licenciaturas e mestrados s reais necessidades dos empregadores, seja atravs da realizao de formaes que permitam aos trabalhadores no activo ou no desemprego aumentar, actualizar, diversificar e aprofundar os seus conhecimentos, para melhorarem a sua empregabilidade e melhor competirem a nvel nacional e internacional, de modo a constituirem uma mais valia para as organizaes onde trabalham. O ISCAP tentou j essa via com sucesso, com a oferta de dois cursos, um na rea da contabilidade e fiscalidade e outro na rea da traduo.
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The present paper describes a procedure to isolate volatiles from rock-rose (Cistus ladanifer L.) using simultaneous distillationextraction (SDE). High-value volatile compounds (HVVC) were selected and the influence of the extraction conditions investigated. The effect of the solvent nature and extraction time on SDE efficiency was studied. The best performance was achieved with pentane in 1 h operation. The extraction efficiencies ranged from 65% to 85% and the repeatability varied between 4% and 6% (as a CV%). The C. ladanifer SDE extracts were analysed by headspace solid phase microextraction (HS-SPME) followed by gas chromatography with flame ionization detection (GC-FID). The HS-SPME sampling conditions such as fiber coating, temperature, ionic strength and exposure time were optimized. The best results were achieved with an 85 m polyacrylate fiber for a 60 min headspace extraction at 40C with 20% (w/v) of NaCl. For optimized conditions the recovery was in average higher than 90% for all compounds and the intermediate precision ranged from 4 to 9% (as CV %). The volatiles -pinene (22.2 mg g1 of extract), 2,2,6-trimethylcyclohexanone (6.1 mg g1 of extract), borneol (3.0 mg g1 of extract) and bornyl acetate (3.9 mg g1 of extract) were identified in the SDE extracts obtained from the fresh plant material.
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A new procedure for determining eleven organochlorine pesticides in soils using microwave-assisted extraction (MAE) and headspace solid phase microextraction (HS-SPME) is described. The studied pesticides consisted of mirex, - and -chlordane, p,p-DDT, heptachlor, heptachlor epoxide isomer A, -hexachlorocyclohexane, dieldrin, endrin, aldrine and hexachlorobenzene. The HS-SPME was optimized for the most important parameters such as extraction time, sample volume and temperature. The present analytical procedure requires a reduced volume of organic solvents and avoids the need for extract clean-up steps. For optimized conditions the limits of detection for the method ranged from 0.02 to 3.6 ng/g, intermediate precision ranged from 14 to 36% (as CV%), and the recovery from 8 up to 51%. The proposed methodology can be used in the rapid screening of soil for the presence of the selected pesticides, and was applied to landfill soil samples.
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A procedure for the determination of seven indicator PCBs in soils and sediments using microwave-assisted extraction (MAE) and headspace solid-phase microextraction (HS-SPME) prior to GC-MS/MS is described. Optimization of the HS-SPME was carried out for the most important parameters such as extraction time, sample volume and temperature. The adopted methodology has reduced consumption of organic solvents and analysis runtime. Under the optimized conditions, the method detection limit ranged from 0.6 to 1 ng/g when 5 g of sample was extracted, the precision on real samples ranged from 4 to 21% and the recovery from 69 to 104%. The proposed method, which included the analysis of a certified reference material in its validation procedure, can be extended to several other PCBs and used in the monitoring of soil or sediments for the presence of PCBs.
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Thin films of Cu2SnS3 and Cu3SnS4 were grown by sulfurization of dc magnetron sputtered SnCu metallic precursors in a S2 atmosphere. Different maximum sulfurization temperatures were tested which allowed the study of the Cu2SnS3 phase changes. For a temperature of 350 C the films were composed of tetragonal (I -42m) Cu2SnS3. The films sulfurized at a maximum temperature of 400 C presented a cubic (F-43m) Cu2SnS3 phase. On increasing the temperature up to 520 C, the Sn content of the layer decreased and orthorhombic (Pmn21) Cu3SnS4 was formed. The phase identification and structural analysis were performed using x-ray diffraction (XRD) and electron backscattered diffraction (EBSD) analysis. Raman scattering analysis was also performed and a comparison with XRD and EBSD data allowed the assignment of peaks at 336 and 351 cm1 for tetragonal Cu2SnS3, 303 and 355 cm1 for cubic Cu2SnS3, and 318, 348 and 295 cm1 for the Cu3SnS4 phase. Compositional analysis was done using energy dispersive spectroscopy and induced coupled plasma analysis. Scanning electron microscopy was used to study the morphology of the layers. Transmittance and reflectance measurements permitted the estimation of absorbance and band gap. These ternary compounds present a high absorbance value close to 104 cm1. The estimated band gap energy was 1.35 eV for tetragonal (I -42m) Cu2SnS3, 0.96 eV for cubic (F-43m) Cu2SnS3 and 1.60 eV for orthorhombic (Pmn21) Cu3SnS4. A hot point probe was used for the determination of semiconductor conductivity type. The results show that all the samples are p-type semiconductors. A four-point probe was used to obtain the resistivity of these samples. The resistivities for tetragonal Cu2SnS3, cubic Cu2SnS3 and orthorhombic (Pmn21) Cu3SnS4 are 4.59 102 cm, 1.26 102 cm, 7.40 104 cm, respectively.
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Dissertao apresentada para obteno do grau de Mestre em Bioorgnica
