593 resultados para halogenated phenols


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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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This study investigated the main methods of separation of components of lignocellulosic biomass, with an emphasis on obtaining lignin and its application. The work was developed based on the concept of Biorefinery proposing full use of renewable raw materials and / or the use of lignocellulosic agricultural residues by biochemical or biotechnological conversion in obtaining high value added products with minimal environmental impact. From this premise, a literature review was performed in refereed journal articles and theses in order to gather enough material for critical analysis of usual and alternative methods in the literature. When researching methods that add value to lignin, it was found that with the technology found today, the cost required to have a degree of competitiveness is still too high, preventing much of the process. However, the isolated lignin can be used as raw material in the production of numerous types of biocomposites and polymers and other products such as phenols, benzene, dispersants, vanillin, emulsifying agents, antioxidants, pesticides, fertilizers, charcoal, concrete additives, among others. As an industrial production level is necessary, because the consumption of biomass will only grow over the years, it is necessary that new methods or technologies to be created in order to facilitate the extensive use of lignocellulosic biomass

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We live in a world of chemicals. Unfortunately, some of the characteristics that make household chemical products the most useful are the same qualities that lead to trouble when these products are carelessly handled. A chemical stain or spot is a serious kind of stain that is appearing with increasing frequency and is different from ordinary stains. This type of discoloration or color is caused by a variety of chemical ingredients contains in dozens of common household products. This NebFact discusses the different chemical spots, stains and discolorations that are found in your home furnishings.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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This study investigated the main methods of separation of components of lignocellulosic biomass, with an emphasis on obtaining lignin and its application. The work was developed based on the concept of Biorefinery proposing full use of renewable raw materials and / or the use of lignocellulosic agricultural residues by biochemical or biotechnological conversion in obtaining high value added products with minimal environmental impact. From this premise, a literature review was performed in refereed journal articles and theses in order to gather enough material for critical analysis of usual and alternative methods in the literature. When researching methods that add value to lignin, it was found that with the technology found today, the cost required to have a degree of competitiveness is still too high, preventing much of the process. However, the isolated lignin can be used as raw material in the production of numerous types of biocomposites and polymers and other products such as phenols, benzene, dispersants, vanillin, emulsifying agents, antioxidants, pesticides, fertilizers, charcoal, concrete additives, among others. As an industrial production level is necessary, because the consumption of biomass will only grow over the years, it is necessary that new methods or technologies to be created in order to facilitate the extensive use of lignocellulosic biomass

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Laurencia dendroidea shows high inter- and intrapopulation variability in the amount of the sesquiterpene elatol, caused by genetic variation as well as environmental factors. To test the independent effect of physical and nutritional conditions, the growth and the levels of elatol in L. dendroidea clones were evaluated under different conditions of temperature, salinity, irradiance, and culture medium in the laboratory. Growth of L. dendroidea was clearly affected by all these factors, but elatol levels were influenced only by temperature and salinity. Better conditions for growth did not produce a similar effect on elatol production in L. dendroidea, contradicting the carbon/nutrient balance and growth/differentiation balance models. On the contrary, severe conditions of temperature and salinity promoted a decrease in elatol levels, as predicted by the environmental stress model. Our results using clones indicated that abiotic factors clearly take part in fostering chemical variations observed in natural populations, in addition to genetic factors, and can promote differential susceptibility of plant specimens to natural enemies.

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Ethanol extracts of powdered genipap (Genipa americana L), umbu (Spondia tuberosa A.) and siriguela (Spondia purpurea L) prepared from separate pulp, seeds and peel were investigated for their (i) antioxidant capacity, which was evaluated by various known methods; (ii) acetylcholinesterase (AChE) inhibitory activity; and (iii) cytotoxic effect on corneal epithelial cells of sheep. The highest values of total phenolic content were obtained with peel and seed extracts. Siriguela and umbu (seeds and peel) extracts displayed the highest antioxidant activities. Lipid peroxidation assays using mimetic biomembranes and mouse liver homogenates indicated that genipap pulp is a promising antioxidant. The investigation of phenols and organic acid contents revealed the presence of quercetin, citric and quinic acids, chlorogenic acid derivatives, among others, in several extracts, with the highest amount found in siriguela seeds. Genipap pulp and siriguela seed ethanol extracts presented an AChE inhibition zone similar to that of the positive control, carbachol. AChE inhibition assay with chlorogenic acid, one of the main constituents of siriguela seeds, revealed that this acid showed activity similar to that of the control physostigmine. These data suggest that these extracts are potentially important antioxidant supplements for the everyday human diet, pharmaceutical and cosmetic industries. (C) 2012 Elsevier Ltd. All rights reserved.

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Este trabalho teve como objetivo avaliar o tratamento de água bruta proveniente de um reservatório de água, utilizando instalação piloto de dupla filtração (DF), composta por filtro ascendente de pedregulho (FAP) e filtro rápido descendente de areia (FRD), seguida de uma unidade de pós-tratamento com carvão ativado granular (CAG). Adicionalmente, foi verificado o efeito da pré e interoxidação (entre o FAP e o FRD) na eficiência global do tratamento e na formação de subprodutos orgânicos halogenados (SOH). Em função dos resultados obtidos, foi observado que a pré-oxidação melhorou a qualidade do efluente do FAP e a interoxidação favoreceu que resultassem valores menores de turbidez e cor no efluente do FRD. O processo de tratamento por adsorção em carvão ativado granular, utilizado como pós-tratamento, mostrou-se eficiente para assegurar a qualidade dos efluentes finais nos ensaios realizados, especialmente, em relação à remoção de matéria orgânica, cianobactérias e cor. As concentrações máximas de SOH encontrados nos efluentes do FRD e do FCAG não ultrapassaram os valores limites da Portaria nº 2.914/2011 do Ministério da Saúde.

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Context: Neolignans are usually dimers formed by oxidative coupling of allyl and propenyl phenols, and the neolignan analogue, 2-phenoxy-1-phenylethanone (LS-2) is a promising antimycobacterial compound showing very weak cytotoxicity in mammalian cells and lack of acute toxicity in murine models. Objectives: To investigate the mechanism of action of LS-2 in rat hepatocytes by evaluating the activity levels of enzymes related to oxidation status and drug-metabolizing activity. Materials and methods: Hepatocytes were treated with LS-2 from 0.05 up to 1 mM, for 24 and 48 h, and reduced glutathione (GSH), lipid peroxidation and cytochrome P450 enzyme (CYP450) activity were assayed. A homologous series of phenoxazone ethers were used as substrates to measure the enzymatic profile. The biotransformation of LS-2 was studied in hepatocytes by gas chromatography-mass spectrometry (GC-MS) for detection and analysis of possible metabolites. Results: Hepatocytes treated with LS-2 up to 1 mM for 24 or 48 h did not induce the formation of GSH and lipid peroxidation. O-Dealkylation activities of the isoenzymes CYP4501A1, CYP4501A2, CYP4502B1 and CYP4502B2 were also not detected in the hepatocytes treated with LS-2 for 24 or 48 h. Discussion and conclusion: The results indicate that LS-2 or its two detected metabolites, 2-phenoxy-1-phenylethanol and 2,4-(2-hydroxy-2-phenylethoxy) phenol, are not cytotoxic to rat hepatocytes. These compounds maintain a balance between the production of pro-oxidant agents and their respective antioxidant systems. The data show that enzymes related to oxidation status and drug-metabolizing activities are not involved in the mechanism of action of LS-2.

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In Brazil, citrus black spot (CBS) caused by Guignardia citricarpa is a major disease that has different symptoms on fruit. In this study, fruit of Citrus sinensis infected by G. citricarpa and showing the symptoms false melanosis, freckle spot and hard spot were cross-sectioned and analysed anatomically and histochemically by light microscopy. Immuno-histological assays were performed. All symptoms were accompanied by a thickening of the cuticle. False melanosis lesions did not contain pycnidia and remained restricted to the epicarp or to the first layers of the mesocarp. The stomata in this type of lesion showed phenolic compounds in the guard cells and in the sub-stomatal chamber. In some samples, the guard cells and their surrounding cells lysed, and a wound meristem began to form underneath them. Freckle spot and hard spot lesions had very similar histological alterations to the epicarp and mesocarp, but in our samples only hard spot lesions contained pycnidia. Both of these symptoms were accompanied by protein inclusions. Epidermal and sub-epidermal cells located in the oil-gland region were obliterated, causing alterations in these structures. All symptoms had regions that stained strongly for lipids and phenols.

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A sensitive electrochemical sensor was successfully developed on multi-walled carbon nanotubes (MWCNT) and cobalt phthalocyanine (CoPc) modified glassy carbon electrode (GC), and used to detect byproducts formed after the electrolysis of benzene. The GC/MWCNT/CoPc electrode was applied in the detection of phenolic compounds using square wave voltammetry (SWV). The proposed sensor exhibited a sequence in the sensitivity of the tested phenols: catechol > hydroquinone > resorcinol > phenol and 1,4-benzoquinone. The detection limits for individual phenols were also calculated: catechol (15.62 mu g L-1), hydroquinone (17.91 mu g L-1), resorcinol (46.12 mu g L-1), phenol (58.83 mu g L-1) and 1,4-benzoquinone (13.75 mu g L-1). The proposed sensor was successfully applied in the determination of the total amount of phenols formed after the benzene oxidation, and the obtained results were in full agreement with those from the HPLC procedure. (C) 2012 Elsevier B.V. All rights reserved.

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This study investigated the application of an advanced oxidation process combining hydrogen peroxide with ultraviolet radiation (H2O2/UV) to remove recalcitrant compounds from Kraft bleaching effluent. Anaerobic pre-treatment was performed to remove easily degraded organics using a horizontal-flow anaerobic immobilized biomass (HAIB) reactor. Bleaching plant effluent was treated in the HAIB reactor processed over 19 h of hydraulic retention time (HRT), reaching the expected removal efficiencies for COD (61 +/- 3%), TOC (69 +/- 9%), BOD5 (90 +/- 5%) and AOX (55 +/- 14%). However, the anaerobic treatment did not achieve acceptable removal of UV254 compounds. Furthermore, there was an increase of lignin, measured as total phenols. The H2O2/UV post-treatment provided a wide range of removal efficiencies depending on the dosage of hydrogen peroxide and UV irradiation: COD ranged from 0 to 11%, UV254 from 16 to 35%, lignin from 0 to 29% and AOX from 23 to 54%. All peroxide dosages applied in this work promoted an increase in the BOD5/COD ratio of the wastewater. The experiments demonstrate the technical feasibility of using H2O2/UV for post-treatment of bleaching effluents submitted to anaerobic pre-treatment.