Biblioteca Digital

Este trabalho apresenta o estudo da degradação eletroquímica e eletroquímica foto-assistida de efluentes têxteis industriais usando ânodos dimensionalmente estáveis (ADE). As amostras analisadas foram coletadas diretamente do tanque de equalização (efluente bruto) e do tanque final (efluente biologicamente tratado) cedidas pela empresa Toalhas São Carlos, de São Carlos, São Paulo. As degradações foram realizadas em uma célula de fluxo do tipo filtro prensa com eletrodo ADE comercial (composição nominal Ti/Ti0,7Ru0,3O2) sob recirculação constante. A fim de avaliar os melhores parâmetros de degradação, foram estudadas as influências do tipo de eletrólito suporte (NaCl e Na2SO4), concentrações de NaCl (0,05 a 0,30 mol L-1), densidade de corrente (10 a 120 mA cm-2) e pH (4, 7, 8, 9 e 12). Após definição dos melhores parâmetros, novas amostras do tanque de equalização foram coletadas, em dias alternados para avaliar a influência da composição do efluente. Ensaios eletroquímicos foto-assistidos foram realizados nas mesmas condições que os ensaios eletroquímicos visando a comparação dos métodos. Caracterizações do ADE foram realizadas por voltametria cíclica na ausência e presença de efluente e de luz. Durante as eletrólises de 2 horas...

Agrotóxicos são frequentemente relatados na literatura em contaminações de ambientes aquáticos, sendo provenientes do lixiviamento de solos, do descarte inadequado de embalagens agrícolas, dentre outros. Nesse contexto, os processos oxidativos avançados (POA) têm sido estudados como alternativa para o tratamento desses compostos em meio aquoso. Os POA consistem na oxidação de compostos orgânicos pela formação de radicais livres com alto poder oxidante. Diante desses aspectos, o presente trabalho teve como proposta o estudo da degradação dos herbicidas hexazinona e diuron, aliada ao planejamento experimental do tipo composto central, a fim de otimizar o processo de degradação. Para tanto, realizaram-se as degradações através dos processos H2O2/UV e foto-Fenton em concentrações iniciais próximas a 7 e 20 mg L-1 para a hexazinona e diuron, respectivamente. Os experimentos foram conduzidos em um reator fotoquímico (200 mL a 25 °C) com aplicação de irradiação UV, proveniente de uma lâmpada de Hg (degradação H2O2/UV) e de luz negra (degradação foto-Fenton). No processo via H2O2/UV foram avaliadas a concentração de H2O2 (0,65 a 13,34 mmol L-1) e pH (2,77 a 11,23), e para o processo foto-Feton avaliou-se a concentração de H2O2 (0...

A degradação de antibiótico tetraciclina (TeC) foi avaliada por vários processos a saber, eletroquímico, eletroquímico foto-assistido, Fenton e foto-Fenton. Uma vez que este tipo de antibiótico é excretado principalmente pelo sistema urinário, o meio selecionado foi uma mistura de sais predominantes na composição de urina, a qual apresenta alta concentração de diferentes íons, especialmente íons cloretos. As degradações eletroquímica e eletroquímica foto-assistida foram realizadas em uma célula de fluxo do tipo filtro-prensa, usando um ânodo dimensionalmente estável comercial com composição nominal Ti/Ru0,3Ti0,7O2. O decaimento da concentração do TeC foi determinado por cromatografia líquida de alta eficiência (CLAE) e a remoção da carga orgânica por análise de carbono orgânico total (COT). Os processos de degradação eletroquímica e eletroquímica foto-assistido utilizaram densidades de correntes de 20 a 40 mA cm-2 e concentração inicial de TeC de 200 mg L-1. Aplicando 30 mA cm-2, após duas horas a remoção de TeC foi de 91% e 98%, utilizando processo eletroquímico sem e com foto- assistência, respectivamente. A remoção de COT foi incompleta com um máximo de 17%. A fim de comparar o efeito da mistura salina sobre a degradação de TeC...

A utilização de radiofármacos no diagnóstico de doenças do organismo humano tem aumentado de forma significativa nas últimas décadas. O crescente desenvolvimento de novos reagentes liofilizados (RL) para a preparação de radiofármacos, embora proporcionem uma maior variedade para o mercado de radiofármacos, deixa evidente uma das lacunas na pesquisa radiofarmacêutica: a identificação de produtos de degradação. No presente trabalho, foram identificados os principais produtos de degradação dos RL de ácido 2,3-Dimercaptosuccínico (DMSA) e Etilenodicisteína Dietil Éster (ECD) utilizando as técnicas de cromatografia líquida de alta eficiência com Detecção por Arranjo de Diodos (HPLC-DAD) e cromatografia líquida acoplada à espectrometria de massas de múltiplos estágios (LC-MSn). Realizou-se o estudo de degradação forçada do RL de DMSA e do RL de ECD nas condições de estresse hidrolítico, fotolítico, oxidativo e termodegradação. As análises foram realizadas em equipamento HPLC-DAD Shimadzu e espectrômetro de massas Bruker Daltonics. Todas as análises foram desenvolvidas utilizando coluna cromatográfica Shim-Pack VP-ODS (150 mm x 4,6 mm; 5 μm). O DMSA apresentou tempo de retenção de 5,58 minutos e m/z 204...

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Parameters that influence the zero valent iron mediated degradation of the pharmaceutical diazepam (DZP) were evaluated including the iron concentration and its pre-treatment, the effect of complexation with EDTA and oxic versus anoxic condition. It was observed that acid pre-treatment of iron particles is important for degradation efficiency and that H2SO4 is a better choice than HCl, resulting in higher degradation of DZP. Under oxic conditions, the degradation of DZP achieved 96% after 60 min using Fe-o (25 g L-1) pre-treated with H2SO4 in the presence of EDTA (119 mg L-1), while mineralization achieved around 60% after the same time. Under anoxic conditions, degradation occurred, however at lower extent, achieving 67% after 120 min. The addition of EDTA improved the treatment efficiency in 20% leading to 99% DZP degradation after 120 min. The first intermediates formed during DZP degradation were identified using LC/MS analysis and revealed the formation of mono- and di-hydroxylated products from DZP during Fe-o/EDTA/O-2 degradation, which evidences that OH was the main oxidizing species formed in this process. (C) 2012 Elsevier Ltd. All rights reserved.

The degradation phenomena of ZnO and SnO2-based varistors were investigated for two different degradation methods: DC voltage at increased temperature and degradation with 8/20 μs pulsed currents (lightning type). Electrostatic force microscopy (EFM) was used to analyze the surface charge accumulated at grain-boundary regions before and after degradation. Before the degradation process, 85% of the barriers are active in the SnO2 system, while the ZnO system presents only 30% effective barriers. Both systems showed changes in the electrical behavior when degraded with pulses. In the case of the ZnO system, the behavior after pulse degradation was essentially ohmic due to the destruction of barriers (about 99% of the interfaces are conductive). After the degradation with 8/20 μs pulsed currents, the SnO2 system still presents nonohmic behavior with a significant decrease in the quantity of effective barriers (from 85% to 5%). However, when the degradation is accomplished with continuous current, the SnO2 system exhibits minimum variation, while the ZnO system degrades from 30% to 5%. This result indicates the existence of metastable defects of low concentration and/or low diffusion in the SnO2 system. High energy is necessary to degrade the barriers due to defect annihilation in the SnO2 system. © 2013 The American Ceramic Society.

Degradation of cytochrome P-450 was studied in adult rat liver parenchymal cells in primary monolayer culture. In cells incubated in standard culture medium, the amount of cytochrome P-450 decreased at an accelerated rate relative to either the rate of degradation of total protein in the cells or the turnover of cytochrome P-450 in vivo. This change was succeeded by a spontaneous increase in the activity of haem oxygenase, an enzyme system that converts haem into bilirubin in vitro, measured in extracts from the cultured cells. This finding suggests that the rate of cytochrome P-450 breakdown may be controlled by factor(s) other than the activity of haem oxygenase. The decline in cytochrome P-450 and the subsequent increase in haem oxygenase activity was prevented by incubation of hepatocytes in medium containing an inhibitor of protein synthesis such as cycloheximide, puromycin, actinomycin D, or azaserine. The effect of cycloheximide appeared to be due to decreased breakdown of microsomal 14C-labelled haem. By contrast, cycloheximide was without effect on the degradation of total protein, measured either in homogenates or in microsomal fractions prepared from the cultured cells. These results suggest that the conditions of cell culture stimulate selective degradation of cytochrome P-450 by a process that is inhibited by cycloheximide and hence may require protein synthesis. The findings in culture were verified in parallel studies of cytochrome P-450 degradation in vivo. After administration of bromobenzene...

MDM2 plays a major role in cancer development and progression via both p53-dependent and -independent functions. One of its p53-independent functions is the induction of the ubiquitin-independent proteasomal degradation of p21Waf1. The present study was designed to characterize the mechanism(s) by which MDM2 induces p21Waf1 degradation. We first determined the regions of MDM2 required for p21Waf1 degradation using pulldown assays and Western blotting and then examined the mechanisms using limited proteolysis and fluorescence resonance energy transfer assays. We found that the MDM2-p21Waf1 interaction depended on the central domain of MDM2 and that nuclear localization of both proteins was necessary for p21Waf1 degradation. Specifically, amino acids 226–250 of MDM2 were required for p21Waf1 binding and degradation, and amino acids 251–260 were necessary for p21Waf1 degradation. The latter region induced a conformation change in p21Waf1, increasing its interaction with the C8 subunit of the proteasome, leading to its degradation. When MDM2 lacked either segment (aa 226–250 or aa 251–260), its capacity to promote p21Waf1 degradation and cell cycle progression was significantly reduced. In summary, the present study elucidated a previously unknown mechanism by which MDM2 promotes the degradation of an intact protein (p21Waf1) through an ubiquitin-independent proteasomal degradation pathway. Because MDM2 also increases the degradation of other proteins in a ubiquitin-independent manner...

Vitamin C and its degradation products participate in chemical modifications of proteins in vivo through non-enzymatic glycation (Maillard reaction) and formation of different products called advanced glycation end products. Vitamin C levels are particularly high in selected tissues, such as lens, brain and adrenal gland, and its degradation products can inflict substantial protein damage via formation of advanced glycation end products. However, the pathways of in vivo vitamin C degradation are poorly understood. Here we have determined the levels of vitamin C oxidation and degradation products dehydroascorbic acid, 2,3-diketogulonic acid, 3-deoxythreosone, xylosone, and threosone in the human lens using o-phenylenediamine to trap both free and protein-bound adducts. In the protein-free fraction and water-soluble proteins (WSP), all five listed degradation products were identified. Dehydroascorbic acid, 2,3-diketogulonic acid, and 3-deoxythreosone were the major products in the protein-free fraction, whereas in the WSP, 3-deoxythreosone was the most abundant measured dicarbonyl. In addition, 3-deoxythreosone in WSP showed positive linear correlation with age (p < 0.05). In water-insoluble proteins, only 3-deoxythreosone and threosone were detected...

Mapping and monitoring land degradation in areas under human-induced stresses have urgent tasks in remote sensing whose importance has not yet been fully appreciated. In this study, a surface cover index (SCI) is developed to evaluate and map potential land degradation risks associated with deforestation and accompanying soil erosion in a Western Brazilian Amazon rural settlement study area. The relationships between land-use and land-cover (LULC) types and land degradation risks as well as the impacts of LULC change on land degradation are examined. This research indicates that remotely sensed data can be effectively used for identification and mapping of land degradation risks and monitoring of land degradation changes in the study area. Sites covered by mature forest and advanced successional forests have low land degradation risk potential, while some types of initial successional forests, agroforestry/perennial agriculture and pasture have higher risk potential. Deforestation and associated soil erosion are major causes leading to land degradation, while vegetation regrowth reduces such problems.; 2007

Un protocole inspiré du test de simulation 309 de l’Organisation de coopération et de développement économiques (OCDE) nous a permis de mesurer la dégradation chimique (excluant la photolyse) dans des eaux de surface de même que la dégradation chimique et biologique de neuf contaminants émergents dans l’effluent d’un décanteur primaire d’eau usée municipale. Les données étaient compatibles avec le modèle de cinétique de pseudo ordre un. Les résultats démontrant une persistance de plus d’un an dans les eaux de surface et de 71 jours dans l’effluent du décanteur primaire suggèrent que les dégradations chimique et biologique ne contribuent pas significativement à la diminution de: atrazine, déséthylatrazine, carbamazépine et diclofénac dans la phase aqueuse des systèmes testés. Les autres composés se sont dégradés à différents niveaux. Le 17ß-estradiol ainsi que l’éthinylestradiol, la noréthindrone, la caféine et le sulfaméthoxazole ont tous été sujet à la dégradation biologique dans les effluents du décanteur primaire d’eau usée avec des constantes de dégradation k et des demi-vies t1/2 mesurées allant respectivement de 0.0082 à 0.59 j-1 et de 1.2 à 85 jours. Les paramètres de cinétique mesurés peuvent être combinés aux concentrations typiques des composés à l’étude dans un décanteur primaire d’eau usée pour y calculer leur vitesse de dégradation. Cependant...

The report is a first step in a process towards the use of environmental damage cost assessments, for priority setting, and as an instrument for integrating environment, into economic, and social development. The report provides estimates of damage, and remediation cost for several areas of the environment, and, as areas of priority are identified, further analysis would be required for more accurate estimates. The damage cost of environmental degradation in Egypt in 1999, is estimated at 3.2-6.4 percent of GDP, with a mean estimate of 4.8 of GDP. In addition, the damage cost to the global environment is estimated at 0.6 percent of GDP. The cost of air pollution is assessed at 1.1-3.2 percent of GDP (urban outdoor and rural indoor), followed by soil degradation at 1.0-1.4 percent (erosion and salinity). In the area of water, the damage cost is estimated at 0.7-1.2 percent of GDP (mostly from the lack of safe water, sanitation and hygiene). Cost of coastal zone degradation is estimated at 0.2.-0.4 percent of GDP...

This report is the first step in a process toward using environmental damage cost assessments for priority setting and as an instrument for integrating environmental issues into economic and social development. The report provides estimates of damage cost for several areas of the environment: air, water, land and forests, and waste disposal. The estimates should be considered as orders of magnitude and a range is provided to indicate the level of uncertainty. As areas of priority are identified, further analysis will be required for more accurate estimates. Due to data limitations, the damage cost of environmental degradation has not been estimated in several areas: industrial, hazardous, and hospital waste disposal; unsanitary landfills; degradation of natural ecosystems and biodiversity; and groundwater resource degradation and over-extraction. In addition and due to the complexity of the problem, the report only partially captures damage resulting from soil degradation. The report points t the need to further assess and quantify current and potential future damage costs related to those impacts.

During the Fifth Replenishment Phase of the Global Environment Facility (GEF-5), portfolio monitoring and learning review were introduced as key components of knowledge management in the GEF Secretariat. These strategies were intended to address the need to generate knowledge on innovative practices, experiences, and lessons from projects financed by the GEF. In that regard, the Land Degradation focal area strategy for GEF-5 specifically included a learning objective on the catalytic effect of the GEF integrated Approaches, practices focused on integrating the management of land, soil, water, biodiversity, and biomass, in production systems (agriculture, rangelands, and forest landscapes). The focal area strategy embodies the landscape approach and integrated ecosystem management principles to maximize the global environmental benefits of combating land degradation. As a result of that focus, the strategy also addresses the need to harness and safeguard ecosystem services (carbon cycling, biodiversity...

Die Cytomegalieviren haben verschiedene Mechanismen entwickelt, um die Immunantwort des Wirtes zu umgehen. Eine Strategie ist, die MHC Klasse I-assoziierte Antigenpräsentation auf der Oberfläche infizierter Zellen zu verhindern. Das Genprodukt des m06-Gens von MCMV spielt bei diesem Prozess eine entscheidende Rolle. m06/gp48 ist ein Typ I-Transmembranglykoprotein und bindet im Endoplasmatischen Retikulum an neusynthetisierte, b2-Mikroglobulin-assoziierte MHC Klasse I-Moleküle. Dieser Komplex wird nach dem Verlassen des ERs in die Lysosomen transportiert und dort rasch abgebaut. In der vorliegenden Arbeit konnte gezeigt werden, dass nicht an MHC Klasse I-Moleküle gebundenes gp48 durch das Proteasom abgebaut wird. In Gegenwart spezifischer proteasomaler Inhibitoren wird gp48 in seiner Endo H-sensitiven Form stabilisiert, nicht aber MHC Klasse I-Moleküle. Weiterhin konnte gezeigt werden, dass die Degradation von freiem g48 hauptsächlich im ER/'ER-cis-Golgi intermediate Compartment' (ERGIC) der Zelle stattfindet. Durch die Kombination isolierter Mikrosomen aus gp48-exprimierenden Zellen mit aufgereinigtem Proteasom wurde ein in vitro-Modellsystems zur proteasomalen Degradation entwickelt. In diesem System konnte zum ersten Mal demonstriert werden...

Le VIH-1 a développé plusieurs mécanismes menant à la dégradation de son récepteur cellulaire, la molécule CD4, dans le but d’augmenter la relâche de particules virales infectieuses et d’éviter que la cellule soit surinfectée. L’un de ces mécanismes est la dégradation, induite par la protéine virale Vpu, du CD4 nouvellement synthétisé au niveau du réticulum endoplasmique (RE). Vpu doit lier CD4 et recruter l’ubiquitine ligase cellulaire SCFβ-TrCP, via sa liaison à β-TrCP, afin de dégrader CD4. Puisque CD4 doit être retenu au RE pour permettre à Vpu d’induire sa dégradation via le système ubiquitine-protéasome, il a été suggéré que ce processus implique un mécanisme semblable à une voie cellulaire de dégradation des protéines mal-repliées appelée ERAD (« endoplasmic reticulum-associated degradation »). La dégradation par ERAD implique généralement la dislocation des protéines du RE vers le cytoplasme afin de permettre leur poly-ubiquitination et leur dégradation par le protéasome. Nous avons démontré que Vpu induit la poly-ubiquitination de CD4 dans des cellules humaines. Nos résultats suggèrent aussi que CD4 doit subir une dislocation afin d’être dégradé par le protéasome en présence de Vpu. De plus...

Les maladies cardiovasculaires (MCV) sont la principale cause de mortalité dans les pays industrialisés. L'hypercholestérolémie constitue un facteur de risque majeur pour les MCV. Elle est caractérisée par des niveaux élevés de lipoprotéines de faible densité (LDL, aussi appelé “mauvais cholestérol”). La présence prolongée de haut niveaux de LDL dans la circulation augmente le risque de formation de plaques athérosclérotiques, ce qui peut conduire à l'obstruction des artères et l'infarctus du myocarde. Le LDL est normalement extrait du sang par sa liaison au récepteur du LDL (LDLR) qui est responsable de son endocytose dans les hépatocytes. Des études génétiques humaines ont identifié PCSK9 (proprotein convertase subtilisin/kexin type 9) comme le troisième locus responsable de l'hypercholestérolémie autosomique dominante après le LDLR et son ligand l’apolipoprotéine B-100. PCSK9 interagit avec le LDLR et induit sa dégradation, augmentant ainsi les niveaux plasmatiques de LDL. Les mutations gain de fonction (GF) de PCSK9 sont associées à des niveaux plasmatiques élevés de LDL et à l'apparition précoce des MCV, alors que les mutations perte de fonction (PF) de PCSK9 diminuent le risque de MCV jusqu’à ~ 88% grâce à une réduction du LDL circulant. De ce fait...

Microbial & Biochemical Technology; 2013, S12-006; http://dx.doi.org/10.4172; The herbicide atrazine (2-chloro-4-ethylamine-6-isopropylamine-s-triazine) is extensively used for weed control in sugarcane crops. The application of fungi for the biodegradation of xenobiotics has been studied with promising results. Therefore, atrazine degradation mediated by Pleurotus ostreatus INCQS 40310 was evaluated, and the involvement of ligninolytic enzymes along with the degradation process was also investigated. To promote high degradation percentages and rates, a fractional factorial experimental design was first used to determine the most significant medium components for atrazine degradation. This strategy improved atrazine degradation from 39.0% to 71.0% after 15 days, with the formation of different metabolites. Afterward, a 32 full factorial design was performed using the variables selected in the first part of this study. The salts FeSO4 and MnSO4 showed significant influence in the percentages and the rates of atrazine degradation. The medium optimization resulted in 90.3% and 94.5% of atrazine degradation after 10 days and 15 days, respectively. Although laccase activity was measured during the degradation process, it was not possible to correlate laccase activity with atrazine degradation. The results demonstrated the efficiency of P. ostreatus INCQS 40310 for atrazine degradation...

[FR] L'exploitation de la susceptibilité magnétique des particules du sols pour l'estimation de l'état de développement pédogénétique ou de dégradation des sols par l'érosion repose sur la comparaison des valeurs de la susceptibilité magnétique et de leur évolution en profondeur entre des sols stables de référence et des sols qui ont subi une érosion ou, au contraire, un apport de particules. Des mesures de la susceptibilité magnétique des particules du sol sur 30 cm de profondeur ont été effectués sur quatre zones différentes par la pente et l'utilisation des sols de la couverture pédologique d'un même substrat. Dans la première zone le sol est peu évolué. Il se développe sous une jachère exceptionnellement travaillée. La moyenne des susceptibilités magnétiques mesurées est de 7,41 10-8 m3/kg. Dans la seconde zone le sol est bien développé sur plusieurs décimètres. Il est intensivement exploité par la éréaliculture. La susceptibilité magnétique moyenne est de 23,42 10-8 m3/kg. La troisième zone est un sol qui évolue sous une formation herbacée naturelle (alfa) moyennement dense. La moyenne des susceptibilités magnétique de cette zone est 13,75 10-8 m3/kg. La quatrième zone a complètement perdu son sol...

This work was undertaken to investigate the effect of variations of the feed rate on a fed-batch set-up used to degrade xenobiotics. The mixture of substrates was composed of PCP, 2,4,6 TCP and 2,3,5,6 TeCP (pentachlorophenol, 2,4,6 trichlorophenol and 2,3,5,6 tetrachlorophenol respectively). Two acclimated bacteria isolated from soil were used: Pseudomonas aeruginosa and Achromobacter sp. nov. The different flow rates tested were: I: 0.5 m·ℓmin¹, II: 1.67 m·ℓmin¹ and III: 2.00 m·ℓmin-1. Our results show that during fed-batch operation the 2,4,6 TCP exhibits an earlier degradation than the other compounds, for all of the flow rates tested. This indicates that in this case the degradation of the most recalcitrant compounds (PCP and 2,3,5,6 TeCP) is benefited by the increase in biomass of bacteria, due to the metabolisation of a less recalcitrant compound (2,4,6 TCP). The defined parameter, specific degradation rate (SDR), was demonstrated to be very useful for comparing the degradation abilities at different flow rates of a fed-batch system. The degradation efficiencies were shown to be higher than 90% for all of the cases and to decrease as the feed rate increases. However, the SDR, a parameter that involves the rate of degradation and the biomass...