592 resultados para Phosphoric monoester hydrolases
Resumo:
Anchoíta (Engraulis anchoita) é uma espécie pelágica encontrada no Sudoeste do Oceano Atlântico. Estima-se que 135000 toneladas/ano desse peixe possam ser exploradas ao longo do litoral sul do Brasil. Entretanto, os recursos pesqueiros do país são ainda inexplorados, o que torna esta matéria prima candidata em potencial para a fabricação de novos produtos a base desse pescado. Com o apoio de programas governamentais sociais, a tendência para o Brasil é para o desenvolvimento de produtos de anchoíta alternativos e que sejam capazes de suprir as necessidades específicas de cada grupo de consumo alvo. Dentro desse cenário, um estudo de novos produtos de pescado frente ao mercado se faz necessário, na tentativa de compreender as variáveis influentes do setor. Para tanto, na presente tese teve objetivou-se desenvolver produtos à base de anchoíta e estudar o comportamento do mercado consumidor frente a esses novos produtos de pescado. Um total de seis artigos foi gerado. O primeiro artigo intitulou-se: “Potencial de inserção de empanados de pescado na merenda escolar mediante determinantes individuais”. Neste objetivou-se detectar os determinantes individuais do consumo de pescado com adolescentes em idade de 12 a 17 anos, visando à inserção de empanados de pescado na merenda escolar. Foi verificado que as variáveis que melhor discriminaram a frequência de consumo foram “gosta de pescado” e “grau de escolaridade dos pais”. Os resultados indicaram um potencial de consumo de empanados de pescado por adolescentes, associado à necessidade de educação alimentar. O segundo artigo “Elaboração de hambúrguer a partir de base proteica de anchoíta (Engraulis anchoita)” no qual se objetivou avaliar o efeito de diferentes combinações de solventes para a obtenção de base proteica de anchoíta visando à elaboração de hambúrguer de pescado. As lavagens com ácido fosfórico e mais dois ciclos de água foram as que apresentaram os melhores valores para a obtenção da base proteica, baseando-se na remoção de nitrogenados e respostas sensoriais. No terceiro artigo “Aceitação de empanados de pescado (Engraulis anchoita) na merenda escolar no extremo sul do Brasil” o objetivo foi avaliar a aceitação de empanados de pescado (Engraulis anchoita) com alunos (n = 830) da rede pública de ensino, em idades entre 5 e 18 anos, de duas cidades do estado do Rio Grande do Sul, Brasil. Os resultados indicaram relação inversa entre a aceitação de empanados de pescado e o aumento da idade das crianças. O quarto artigo estudou “Razões subjacentes ao baixo consumo de pescado pelo consumidor brasileiro.” Neste objetivou-se investigar o comportamento referente ao consumo de pescado de uma população com baixo consumo de pescado (Brasil), aplicando a Teoria do Comportamento Planejado (TCP). Os resultados indicaram que tanto a intenção como a atitude provou serem determinantes significativos na frequência de comer pescado, sendo a atitude inversamente correlacionada com o consumo de pescado. Hábito apareceu como uma importante variável discriminante para o consumo de pescado. O quinto artigo intitula-se “Modelagem de equações estruturais e associação de palavras como ferramentas para melhor compreensão do baixo consumo de pescado”. O objetivo foi desenvolver um modelo e explicar o conjunto das relações entre os construtos do consumo de pescado em uma população com baixo consumo de pescado (Brasil) através da aplicação da TCP e pelo Questionário das Escolhas dos Alimentos. Além disso, a percepção cognitiva de produtos de pescado (Engraulis anchoíta) foi avaliada pela mesma população. Os resultados indicaram um bom ajuste para o modelo proposto e mostraram que os construtos “saúde” e “controle de peso” são bons preditores da intenção. A técnica associação de palavras provou ser um método útil para a análise de percepção de um novo produto de pescado, além de ajudar a explicar os resultados obtidos pelas equações estruturais. O sexto e último artigo “Percepção de saudável em produtos de pescado em uma população com alto consumo de pescado. Uma investigação por eye tracking” em que se objetivou explorar o uso do método eye tracking para estudar a percepção de saudável em diferentes produtos de pescado. Dois pontos importantes podem ser salientados como influentes na percepção de saudável: produtos de pescado processados e alimentos fritos.
Resumo:
The chemical changes in clay minerals has been widely studied in order to improve its properties for use in various applications. However kaolinite has strong hydrogen bonds between their adjacent layers hindering the process changes in its structure. With the objective to facilitate the process of intercalation monobasic potassium phosphate, bibasic potassium phosphate and potassium acetate we was performed on kaolinite heat treatment at 600 °C and activated acidic with phosphoric acid and 5 to 10 mol L-1. The samples they were characterized by energy dispersive spectroscopy (EDS), X-Ray Diffraction (XRD), Infrared Spectroscopy Fourier Transform (FTIR) and Thermogravimetric Analysis (TG) and Differential Thermal Analysis (DTG) and the superficial and textural changes the samples with heat treatment and acid activation they were characterized by scanning electron microscopy (SEM) and Textural Analysis of Adsorption/desorption N2. With the help of the techniques found that, the heat treatment becomes more susceptible to acid activation kaolinite making the samples with two treatments show larger amounts of phosphorus. It was also found that bibasic potassium phosphate binds more strongly the structure of kaolinite by having a structure with two-coordinating oxygens and intercalation with potassium acetate in acid-activated kaolin increases the interlayer distance of the kaolinite and the intercalation occurs with higher response index (RI) for samples with acid activation to 5 mol /L.
Resumo:
The supersulfated cement (CSS) basically consist of up to 90% blast furnace slag, 10-20% of a source of calcium sulfate and a small amount of alkali activator, covered by European standard EN 15743/2010. Because of this SSC are considered "green cement" low environmental impact. The source of calcium sulfate used in the preparation of CSS can be obtained from natural sources, such as gypsum or from alternative sources (industrial products), such as phosphogypsum. The phosphogypsum is a by-product of the fertilizer industry, used in the production of phosphoric acid. In this process the phosphate rock is treated with sulfuric acid to give as the major product phosphoric acid (H3PO4), gypsum and a small amount of hydrofluoric acid. The chemical composition of gypsum is basically calcium sulfate dihydrate (CaSO4.2H2O), similar to gypsum, because it can be used in this type of cement. To become anhydrous, the calcination of gypsum is necessary. The availability of the source of calcium sulfate to react with the slag is dependent on its solubility that is directly related to its calcination temperature. The solubility of the anhydrous gypsum decreases with increasing calcination temperature. This study investigated the influence of temperature of calcination of phosphogypsum on the performance of CSS. Samples were prepared with 10 and 20% of phosphogypsum calcinated at 350 to 650 ° C using KOH as an alkaline activator at three different concentrations (0.2, 0.5 and 0.8%). The results showed that all mortars presented the minimum values required by EN 15743/2010 for 7 and 28 days of hydration. In general CSS containing 10% phosphogypsum showed slightly better compressive strength results using a lower calcination temperature (350 °C) and curing all ages. The CSS containing 20% of calcined gypsum at 650 °C exhibit satisfactory compressive strenght at 28 days of hydration, but at later ages (56 to 90 days) it strongly reduced. This indicates that the calcination temperature of phosphogypsum has a strong influence on the performance of the CSS.
Resumo:
When a liquid is irradiated with ultrasound, acoustic cavitation (the formation, growth, and implosive collapse of bubbles in liquids irradiated with ultrasound) generally occurs. This is the phenomenon responsible for the driving of chemical reactions (sonochemistry) and the emission of light (sonoluminescence). The implosive collapse of bubbles in liquids results in an enormous concentration of sound energy into compressional heating of the bubble contents. Therefore, extreme chemical and physical conditions are generated during cavitation. The study of multibubble sonoluminescence (MBSL) and single-bubble sonoluminescence (SBSL) in exotic liquids such as sulfuric acid (H2SO4) and phosphoric acid (H3PO4) leads to useful information regarding the intracavity conditions during bubble collapse. Distinct sonoluminescing bubble populations were observed from the intense orange and blue-white emissions by doping H2SO4 and H3PO4 with sodium salts, which provides the first experimental evidence for the injected droplet model over the heated-shell model for cavitation. Effective emission temperatures measured based on excited OH• and PO• emission indicate that there is a temperature inhomogeneity during MBSL in 85% H3PO4. The formation of a temperature inhomogeneity is due to the existence of different cavitating bubble populations: asymmetric collapsing bubbles contain liquid droplets and spherical collapsing bubbles do not contain liquid droplets. Strong molecular emission from SBSL in 65% H3PO4 have been obtained and used as a spectroscopic probe to determine the cavitation temperatures. It is found that the intracavity temperatures are dependent on the applied acoustic pressures and the thermal conductivities of the dissolved noble gases. The chemical and physical effects of ultrasound can be used for materials synthesis. Highly reactive species, including HO2•, H•, and OH• (or R• after additives react with OH•), are formed during aqueous sonolysis as a consequence of the chemical effects of ultrasound. Reductive species can be applied to synthesis of water-soluble fluorescent silver nanoclusters in the presence of a suitable stabilizer or capping agent. The optical and fluorescent properties of the Ag nanoclusters can be easily controlled by the synthetic conditions such as the sonication time, the stoichiometry of the carboxylate groups to Ag+, and the polymer molecular weight. The chemical and physical effects of ultrasound can be combined to prepare polymer functionalized graphenes from graphites and a reactive solvent, styrene. The physical effects of ultrasound are used to exfoliate graphites to graphenes while the chemical effects of ultrasound are used to induce the polymerization of styrene which can then functionalize graphene sheets via radical coupling. The prepared polymer functionalized graphenes are highly stable in common organic solvents like THF, CHCl3, and DMF. Ultrasonic spray pyrolysis (USP) is used to prepare porous carbon spheres using energetic alkali propiolates as the carbon precursors. In this synthesis, metal salts are generated in situ, introducing porous structures into the carbon spheres. When different alkali salts or their mixtures are used as the precursor, carbon spheres with different morphologies and structures are obtained. The different precursor decomposition pathways are responsible for the observed structural difference. Such prepared carbon materials have high surface area and are thermally stable, making them potentially useful for catalytic supports, adsorbents, or for other applications by integrating other functional materials into their pores.
Resumo:
Betalains are plant derived natural pigments that are presently gaining popularity for use as natural colorants in food industry. Although being betalains from red beetroot already used as food colorant (E- 162), these compounds are not as well studied as compared to other natural pigments such as anthocyanins, carotenoids or chlorophylls (I]. Since food additives are on the focus of public interest, it is becoming increasingly important to meet consumers' expectations for natural and healthy products. Hence, the search for new plant-derived colorants for the food industry is still necessary [2]. Betalains were originally called 'nitrogenous anthocyanins', which incorrectly implied structural similarities between the two pigment classes. There are two structurally different types of betalains: the yellow/orange betaxanthins which are the condensation products of betalamic acid and assorted amino compounds, and the red betacyanins which are formed by glycosylation and acylation of cyclo-DOPA [3]. Looking at the chemical structure of the pigment, the addition of an acid to the extraction solvent will increase the affinity of the pigment with the solvent. The aim of this study was to use Gomphrena globosa L. flowers, as an alternative plant source to obtain these pigments and to evaluate the best acid to be used within the extraction procedure. For that purpose three different acids (acetic, hydrochloric and phosphoric acids, all ofthem allowed by the food industry), adjusted at the same pH, were tested during a maceration extraction procedure. After the extraction a purification through C18 column was performed in order to obtain a more concentrate extract in betacyanins. The results were analysed by HPLC-PDA-MSIESI. The betacyanin profile allowed the identification of gomphrenin IIJIII and isogomphrenin IIIIII and the best results were achieved by performing the extraction procedure using hydrochloric acid (6.6 mg/g extract), while phosphoric acid only presented trace amounts of these compounds. When acetic acid was used, the pigment extracted was 6.8 times less (0.97 mg/g extract) when compared to HCI. In conclusion hydrochloric acid can be considered the most suitable acid to be applied in the extraction procedure of these pigments.
Resumo:
Dissertação (mestrado)—Universidade de Brasília, Faculdade de Ciências da Saúde, Programa de Pós-Graduação em Ciências da Saúde, 2015.
Resumo:
Giardiasis, currently considered a neglected disease, is caused by the intestinal protozoan parasite Giardia duodenalis and is widely spread in human as well as domestic and wild animals. The lack of appropriate medications and the spread of resistant parasite strains urgently call for the development of novel therapeutic strategies. Host microbiota or certain probiotic strains have the capacity to provide some protection against giardiasis. By combining biological and biochemical approaches, we have been able to decipher a molecular mechanism used by the probiotic strain Lactobacillus johnsonii La1 to prevent Giardia growth in vitro. We provide evidence that the supernatant of this strain contains active principle(s) not directly toxic to Giardia but able to convert non-toxic components of bile into components highly toxic to Giardia. By using bile acid profiling, these components were identified as deconjugated bile-salts. A bacterial bile-salt-hydrolase of commercial origin was able to mimic the properties of the supernatant. Mass spectrometric analysis of the bacterial supernatant identified two of the three bile-salt-hydrolases encoded in the genome of this probiotic strain. These observations document a possible mechanism by which L. johnsonii La1, by secreting, or releasing BSH-like activity(ies) in the vicinity of replicating Giardia in an environment where bile is present and abundant, can fight this parasite. This discovery has both fundamental and applied outcomes to fight giardiasis, based on local delivery of deconjugated bile salts, enzyme deconjugation of bile components, or natural or recombinant probiotic strains that secrete or release such deconjugating activities in a compartment where both bile salts and Giardia are present.
Resumo:
Biodiesel is a fuel obtained from vegetable oils, such as soy, castorbean, among others. The monoester of fatty acid of these oils have chains with mono, di and tri double connections. The presence of these insaturations are susceptible to oxidization. Antioxidants are substances able to prevent oxidization from oils, fats, fat foods, as well as esters of Alquila( biodiesel). The objective of this work is to summarize a new antioxidant from the Cashew Nut Shell Liquid (CNSL) using the electrolysis technique. A current of 2 amperes was used in a single cell of only one group and two eletrodos of stainless steel 304 in a solution of methanol, together with the eletrolits: acetic acid, sodium chloride and sodium hydroxide, for two hours of agitation. The electrolysis products are characterized by the techniques of cromatography in a thin layer, spectroscopy of infrared and gravimetric analysis. The material was submitted to tests of oxidative stability made by the techniques of spectropy of impendancy and Rancimat (EN 14112). The analyses of characterization suggest that the polimerization of the electrolytic material ocurred. The application results of these materials as antioxidants of soy biodiesel showed that the order of the oxidative stability was obtained by both techniques used
Resumo:
Aim: To evaluate the influence of ultrasonic activation (US) with different irrigant regimens in smear layer removal. Methods: One hundred bovine incisors were instrumented and divided into ten groups (n=10) according to final irrigation protocols: distilled water (DW); DW+US; 17% EDTA; QMix; 10% citric acid; 37% phosphoric acid; 17% EDTA+US; QMix+US; 10% citric acid+US; 37% phosphoric acid+US. The samples were then submitted to scanning electron microscopy where a score system was used to evaluate the images and effectiveness of proposed treatments. The data were statistically analyzed by Kruskal-Wallis and Mann-Whitney U tests for intergroup comparisons as well as the Wilcoxon and Friedman tests for intragroup comparisons at 5% significance level. Results: In the cervical third, groups 17% EDTA, QMix, 10% citric acid, 17% EDTA+US, QMix+US and 10% citric acid+US were more effective in smear layer removal (p<0.05); in the middle third, groups 17% EDTA+US and QMix+US were more effective in smear layer removal (p<0.05); in the apical third, groups 17% EDTA,17% EDTA+US and QMix+US were more effective in smear layer removal (p<0.05). Conclusions: US can aid 17% EDTA and QMix in smear layer removal at the middle third and QMix at the apical third, contributing to the cleaning of root canal system.
Resumo:
Aim: To assess the effect of adding zinc oxide nanoparticles to dental adhesives on their anti-microbial and bond strength properties. Methods: 45 human premolars were cut at the cement enamel junction (CEJ) and the crowns were sliced into buccal and lingual halves. The specimens were classified into three groups, etched with 37% phosphoric acid for 15 s and rinsed for 30 s. Single Bond, Single Bond+5% zinc oxide and Single Bond+10% zinc oxide were used in the first, second and third groups. A cylinder of Z250 composite was bonded and cured for 40 s. For anti-bacterial testing, 10 samples of each group were assessed by direct contact test; 10 μL of bacterial suspension was transferred into tubes containing adhesives and incubated for one hour; 300 μL of brain heart infusion (BHI) broth was added to each tube and after 12 h, 50 μL of bacteria and broth were spread on blood agar plates and incubated for 24 h. Results: The colony count decreased significantly in the second and third groups compared to the first. Conclusions: Incorporation of zinc oxide nanoparticles into dental adhesives increases their anti-microbial properties without affecting their bond strength.
Resumo:
Background The Grooved Carpet shell clam Ruditapes decussatus is the autochthonous European clam and the most appreciated from a gastronomic and economic point of view. The production is in decline due to several factors such as Perkinsiosis and habitat invasion and competition by the introduced exotic species, the manila clam Ruditapes philippinarum. After we sequenced R. decussatus transcriptome we have designed an oligo microarray capable of contributing to provide some clues on molecular response of the clam to Perkinsiosis. Results A database consisting of 41,119 unique transcripts was constructed, of which 12,479 (30.3%) were annotated by similarity. An oligo-DNA microarray platform was then designed and applied to profile gene expression in R. decussatus heavily infected by Perkinsus olseni. Functional annotation of differentially expressed genes between those two conditionswas performed by gene set enrichment analysis. As expected, microarrays unveil genes related with stress/infectious agents such as hydrolases, proteases and others. The extensive role of innate immune system was also analyzed and effect of parasitosis upon expression of important molecules such as lectins reviewed. Conclusions This study represents a first attempt to characterize Ruditapes decussatus transcriptome, an important marine resource for the European aquaculture. The trancriptome sequencing and consequent annotation will increase the available tools and resources for this specie, introducing the possibility of high throughput experiments such as microarrays analysis. In this specific case microarray approach was used to unveil some important aspects of host-parasite interaction between the Carpet shell clam and Perkinsus, two non-model species, highlighting some genes associated with this interaction. Ample information was obtained to identify biological processes significantly enriched among differentially expressed genes in Perkinsus infected versus non-infected gills. An overview on the genes related with the immune system on R. decussatus transcriptome is also reported.
Resumo:
Different types of heterogeneous catalysts of the silicoaluminophosphate type, (SAPO-5, SAPO-11, SAPO-31, SAPO-34 and SAPO-41), molecular sieves with a: AFI, AEL, ATO, CHA and AFO structure, respectively, were synthesized through the hydrothermal method. Using sources such as hydrated alumina (pseudobohemita), phosphoric acid, silica gel, water, as well as, different types of organic structural templates, such as: cetyltrimethylammonium bromide (CTMABr), di-isopropylamine (DIPA), di-n- propylamine (DNPA) and tetraethylammonium hydroxide (TEOS), for the respective samples. During the preparation of the silicoaluminophosphates, the crystallization process of the samples occurred at a temperature of approximately 200 ° C, ranging through periods of 18-72 h, when it was possible to obtain pure phases for the SAPOs. The materials were furthermore washed with deionized water, dried and calcined to remove the molecules of the templates. Subsequently the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), absorption spectroscopy in the infrared region (FT-IR), specific surface area and thermal analysis via TG/DTG. The acidic properties were determined using adsorption of n-butylamine followed by programmed termodessorption. These methods revealed that the SAPO samples showed a typically weak to moderate acidity. However, a small amount of strong acid sites was also detected. The deactivation of the catalysts was conducted by artificially coking the samples, followed by n-hexane cracking reactions in a fixed bed with a continuous flow micro-reactor coupled on line to a gas chromatograph. The main products obtained were: ethane, propane, isobutene, n-butane, n-pentane and isopentane. The Vyazovkin (model-free) kinetics method was used to determine the catalysts regeneration and removal of the coke
Resumo:
The addition of active silica potentially improves the quality of concrete due to its high reactivity and pore refinement effect. The reactivity of silica is likely related to its charge density. Variations in surface charge alter the reactivity of the material consequently affecting the properties of concrete. The present study aimed at investigating variations in the charge density of silica as a function of acid treatments using nitric or phosphoric acid and different pH values (2.0, 4.0 and 6.0). Effects on concrete properties including slump, mechanical strength, permeability and chloride corrosion were evaluated. To that end, a statistical analysis was carried out and empirical models that correlate studied parameters (pH, acid and cement) with concrete properties were established. The quality of the models was tested by variance analysis. The results revealed that the addition of silica was efficiency in improving the properties of concrete, especially the electrochemical parameters. The addition of silica treated using nitric acid at pH = 4.0 displayed the best cement performance including highest strength, reduced permeability and lowest corrosion current
Resumo:
In this review article recent developments in the asymmetric transfer hydrogenation of imines from 2008 up to today are presented. The main methodology involves either metal-catalyzed procedures in the presence of a chiral ligand or organocatalyzed technologies using a Hantzsch ester and a chiral BINOL-derived phosphoric acid. The most important procedures are collected, paying special attention to the application of this methodology in synthetic organic chemistry.