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Química Nova, Volume: 33, Número: 3, Publicado: 2010
  • A desigualdade só aumenta prejuízos e diminui as oportunidades Editorial

    Torresi, Susana I. Córdoba de; Pardini, Vera L.; Ferreira, Vitor F.
  • Distribuição de Hg total e suas associações com diferentes suportes geoquímicos em sedimentos marinhos da margem continental brasileira: Bacia de Campos - Rio de Janeiro Artigo

    Araujo, Beatriz Ferreira; Almeida, Marcelo Gomes de; Salomão, Marcos Sarmet Moreira Barros; Gobo, Renato Rosa; Siqueira, Verônica Caldas; Ovalle, Álvaro Ramon Coelho; Rezende, Carlos Eduardo de

    Resumo em Inglês:

    Mercury distribution and geochemical support on the Continental Margin was evaluated at the Campos Basin, Rio de Janeiro state, Brazil. The average concentrations for all analyzed elements were, respectively, 20 ± 5 ng g-1 (Hg); 30 ± 14 mg g-1 (Al); 16 ± 6 mg g-1 (Fe), and 254 ± 83 µg g-1 (Mn). Silt and clay content, total carbonate and Hg, and organic carbon increased with depth. Finally, the relationship between Hg and silt clay showed significant positive correlation. Total Hg concentrations are the background level described primarily (~40 ng g-1).
  • Poisoning and regeneration of Pt-Pd/WO3-ZrO2 short paraffin isomerization catalysts

    Canavese, Sergio; Finelli, Zunilda; Busto, Mariana; Benitez, Viviana M.; Vera, Carlos R.; Yori, Juan C.

    Resumo em Inglês:

    WO3-ZrO2 catalysts promoted with Pt and Pd were tested as paraffin isomerization catalysts using n-hexane as model compound. Sulfur and amine poisoning and regeneration tests were used to assess the impact of the addition of Pt and Pd on the deactivation resistance and regenerability. Pt and PtPd catalysts were the most active for n-hexane isomerization. The low activity of the Pd catalyst was attributed to poor Pd metal properties when supported over WO3-ZrO2 and to a decrease of the number of BrQnsted acid sites. PtPd was the only catalyst capable of full regeneration after S poisoning. Amine poisoning completely supressed the isomerization activity and the original activity could only be restored by calcination and reduction.
  • Stability of antioxidants vitamins in bee pollen samples

    Melo, Illana Louise Pereira de; Almeida-Muradian, Ligia Bicudo de

    Resumo em Inglês:

    This study evaluated the stability of vitamins C, E and β-carotene in six samples of bee pollen after their process, and in a one-year period of storage. After the pollen's process, there was a 67.1% increase for vitamin C (p <0.05), an 18.7% loss for vitamin E and 15.6% for β-carotene. Storage in freezer was the most efficient condition for the vitamins conservation; the loss in storage at room temperature (exposed or protected from light) was similar. Vitamin E appears to be better preserved during storage when compared to vitamin C and β-carotene.
  • Determinação de metais traço no material particulado em suspensão em Ouro Preto, Minas Gerais Artigo

    Magalhães, Lucas Carlúcio; Nalini Junior, Hermínio Arias; Lima, Aniel da Costa; Coutrim, Mauricio Xavier

    Resumo em Inglês:

    The determination of the airborne particulate matter (PTS) mass and trace metals concentrations were performed in three sites in Ouro Preto, MG, Brazil. It was evaluated 288 samples. The legal limit of annual geometric average (60 µg m-3) to PTS concentrations didn't exceed, but the legal limit for 24 h (240 µg m-3) did in three measurements. Seven metals (Al, Cr, Cu, Fe, Mn, Ni, Pb) analysed by ICP-AES were quantified in 18 samples. Aluminum and iron showed the highest concentrations, indicating the contribution of the soil and of one aluminum plant. The high nickel concentration is probably due to vehicular emissions and industrial combustion processes.
  • pH effect on the synthesis of magnetite nanoparticles by the chemical reduction-precipitation method

    Andrade, Ângela L.; Souza, Diana M.; Pereira, Márcio C.; Fabris, José D.; Domingues, Rosana Z.

    Resumo em Inglês:

    This work aimed at putting in evidence the influence of the pH on the chemical nature and properties of the synthesized magnetic nanocomposites. Saturation magnetization measurements evidenced a marked difference of the magnetic behavior of samples, depending on the final pH of the solution after reaction. Magnetite and maghemite in different proportions were the main magnetic iron oxides actually identified. Synthesis with final pH between 9.7-10.6 produced nearly pure magnetite with little or no other associated iron oxide. Under other synthetic conditions, goethite also appears in proportions that depended upon the pH of the synthesis medium.
  • Utilization of Sn/Nb2O5 composite for the removal of methylene blue

    Cantão, Fabiane de Oliveira; Melo, Walclée de Carvalho; Oliveira, Luiz Carlos Alves; Passos, Aline Ribeiro; Silva, Adilson Cândido da

    Resumo em Inglês:

    In this work, the oxidation of methylene blue textile dye in the presence of hydrogen peroxide, using niobium oxide impregnated with different proportions of tin (1, 5 and 10% in mass) as catalyst was studied. The materials were characterized by TPR, XPS, XRD and FTIR. The oxidation tests monitored by ESI-MS showed that the composite containing the higher amount of tin was the most efficient in the removal of the dye. The XRD, XPS, and TPR data presented evidence of the formation of the tin-niobium oxide composite containing Sn0 and supported SnO2.
  • Avaliação do desempenho de surfactantes para a solubilização de fases líquidas não aquosas em meio aquoso Artigo

    Souza, Elizabeth Fátima de; Peres, Mariana Rodrigues; Moraes, Samara Boaventura de

    Resumo em Inglês:

    The presence of non-aqueous phase liquids (NAPLs) in the subsurface is a threat to public health as well as a serious environmental issue. NAPLs may remain adsorbed or form lenses floating on aquifers causing long-term contaminations. Surfactants may increase NAPLs solubility, enhancing the pump-and-treatment performance. Size, shape, hydration and ionization degree of the micelles define the affinity and the space available for the solubilization of a particular contaminating agent. The tests carried out at laboratory scale, taking into account the NAPL to be removed and the medium characteristics were useful to select surfactants and evaluate their efficiency as NAPLs solubilizers.
  • Organização supramolecular da ftalocianina de cobalto(II) e seu efeito na oxidação do aminoácido cisteína Artigo

    Santos, Amanda Costa; Luz, Roberto A. Sousa; Ferreira, Luana G. França; Santos Júnior, José Ribeiro dos; Silva, Welter Cantanhêde da; Crespilho, Frank Nelson

    Resumo em Inglês:

    The interest in the chemistry of cobalt (II) tetrasulfonated phthalocyanine (PcTsCo) comes mainly from its macrocycle-ligand structure combined with their special chemical characteristics, such as high solubility, well-defined redox reactions and remarkable optical absorption in the visible region. In this work, we use layer-by-layer technique in order to assemble CoTsPc and poly(allylaminehydrochloride) (PAH) in hybrid supramolecular system. The electronic spectroscopy and cyclic voltammetry techniques were utilized to study PAH/CoTsPc multilayers growth and the cysteine catalytic oxidation. PAH/CoTsPc showed high electrochemical stability and worthwhile to mention is the remarkable influence of supramolecular arrangement on the final redox properties of the system.
  • Biomassa residual para remoção de íons uranilo Artigo

    Boniolo, Milena Rodrigues; Yamaura, Mitiko; Monteiro, Raquel Almeida

    Resumo em Inglês:

    Activities related to nuclear industry, production of phosphoric acid and hospitals have generated considerable volumes of radioactive waste containing uranyl ions. Banana pith was characterized by Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy and was investigated as a biosorbent for uranyl ions from nitric solutions by batch experiments. Influences of adsorbent size, kinetics and equilibrium adsorption were studied. The biosorption of the uranyl ions followed pseudo-second-order kinetics. The adsorption isotherm data were closely fitted to the Freundlich equation.
  • Produção de poli(3-hidroxibutirato) por Cupriavidus Necator em meio hidrolisado de amido de arroz com suplementação de óleo de soja em diferentes temperaturas Artigo

    Dalcanton, Francieli; Ienczak, Jaciane Lutz; Fiorese, Mônica Lady; Aragão, Gláucia Maria Falcão de

    Resumo em Inglês:

    Poly (3-hydroxybutyrate) (P(3HB)) is a biopolymer, completely biodegradable, which has similar properties to fuel-based polymers. However to make it economically competitive it is necessary the study of cheap sources of substrate. The influence of hydrolyzed rice starch supplemented with soybean oil at different temperatures (30, 35 and 40 °C) was studied in the production of P(3HB) by C. necator. The percentage of P(3HB) produced in the cultures at 30, 35 °C was 30, 39% and 35, 43% without and with supplementation of oil, respectively. The culture at 40 °C showed no production phase due to a possible oxygen limitation. These results demonstrate that hydrolyzed rice starch supplemented with soybean oil increases the yield of P(3HB) and temperature of 35 ºC is the most favorable for biopolymer production.
  • Avaliação (em escala laboratorial) da aplicação do processo eletrolítico em efluente de lagoa de estabilização de esgoto urbano Artigo

    Claro, Elis Marina Turini; Otenio, Marcelo Henrique; Bidóia, Edério Dino; Silva, Natália Maria Maciel Guerra; Santos, Valdecir dos

    Resumo em Inglês:

    Physico-chemical and microbiological parameters were evaluated before and after applying an electrolytic process to effluents of a stabilization lagoon, in the presence or absence of "salt". Chlorine generation and bactericidal properties of the treatments were studied following two experiments. Effluent pH increased with electrolysis time. In the absence of "salt", 20 min electrolysis resulted in a COD (Chemical Oxygen Demand) reduction of 44%, along with ca. 99.9% (3 log10 cfu/mL) reduction in total coliforms, heterotrophic bacteria and Escherichia coli. These results indicated that the electrolytic process is a promising complementary technology to improve effluent quality for stabilization lagoons.
  • Efficient synthesis of benzothiazine and acrylamide compounds

    Souza, Ana Maria Alves; Walfrido, Simone Torres Pádua; Leite, Lúcia Fernanda Costa; Lima, Maria Carmo Alves; Galdino, Suely Lins; Pitta, Ivan Rocha; Barbosa Filho, José Maria; Simone, Carlos Alberto De; Ellena, Javier Alcides

    Resumo em Inglês:

    This article describes the synthesis of the new (2Z)-2-(4-methoxybenzylidene)-6-nitro-4H -benzo[1,4]thiazin-3-one, (2Z)-2-(4-methoxybenzylidene)-4-methyl-6-nitro-4H-benzo[1,4]thiazin-3-one, (2Z)-6-amino-2-(4-methoxybenzylidene)-4H -benzo[1,4]thiazin-3-one, (2Z)-6-butylamino-2-(4-methoxybenzylidene)-4-methyl-4H-benzo[1,4]-thiazin-3-one and (2E)-N-alkyl-N-(2-hydroxy-5-nitrophenyl)-3-phenylacrylamides and the spectroscopic data. The arylidenebenzothiazine compounds were prepared using the Knoevenagel condensation with substituted benzaldehydes in the presence of sodium methoxide in DMF. The presence of a nitro substituent in the 4-position, water and a slightly acid reaction medium in this condensation caused the rupture of the benzothiazine ring and subsequent formation of the phenylacrylamide compounds. A crystallographic data was presented for (2E)-3-(4-bromophenyl)-N-dodecyl-N -(2-hydroxy-5-nitrophenyl) acrylamide.
  • Evaluación de la toxicidad de cobre en suelos a través de biomarcadores de estrés oxidativo en eisenia foetida

    Gaete, Hernán; Hidalgo, María Eliana; Neaman, Alexander; Ávila, Gonzalo

    Resumo em Inglês:

    Copper toxicity in soil was evaluated using biomarkers of oxidative stress (catalase enzyme activity, superoxide dismutase and lipid peroxidation) in the earthworm Eisenia foetida. Agricultural topsoils from mining areas of the Aconcagua river basin were collected. Total copper concentrations were in the range of 94-959 mg kg-1, while the exchangeable copper concentrations were in the range of 46-2225 µg kg-1. Earthworms exposed to soil with exchangeable copper concentrations above 32 µg kg-1 showed an increase in catalase activity. Parameters of antioxidant activity were more sensitive than the weight change and thus can be used as appropriate biomarkers in Eisenia foetida.
  • Feoforbídeo (etoxi-purpurina-18) isolado de Gossypium mustelinum (Malvaceae) Artigo

    Silva, Tania Maria Sarmento; Camara, Celso Amorim; Barbosa-Filho, José Maria; Giulietti, Ana Maria

    Resumo em Inglês:

    The phaeophorbide ethyl ester named Purpurin-18 and the flavonoids quercetin and kaempferol were obtained by chromatographic procedures from the chloroform fraction of aerial parts of Gossypium mustelinum. The structure of these compound was determined by NMR, IR and mass spectra data analysis. This is the first occurrence of this compound in Angiosperm.
  • Em busca da sustentabilidade: células solares sensibilizadas por extratos naturais Artigo

    Patrocínio, Antonio Otávio T.; Murakami Iha, Neyde Y.

    Resumo em Inglês:

    The present work reports the use of anthocyanins extracted from mulberry (Morus Alba L.), raspberry (Rubus Idaeus L.) and blueberry (Vaccinium myrtillus L.) as sensitizers in dye-sensitized solar cells. The conversion efficiency of these devices is dependent on the extracts employed and can be rationalized in terms of their composition and spectral properties. Solar cells sensitized by the mulberry extract showed the highest efficiency among the fruits investigated. Moreover, a 16 cm² active area solar cell with the mulberry extract has presented fair good efficiency of conversion for natural dye-based solar cells, besides stability over twenty weeks, showing perspectives for developing these low cost devices with a commercial viability.
  • Síntese hidrotermal de sodalita básica a partir de um rejeito de caulim termicamente ativado Artigo

    Paz, Simone Patrícia Aranha da; Angélica, Rômulo Simões; Neves, Roberto de Freitas

    Resumo em Inglês:

    Basic sodalite was successfully synthesized by hydrothermal method using kaolin waste as source of Aluminum and Silicon. This waste is mainly composed by kaolinite and is produced in large amount by kaolin processing industries for paper coating from the Amazon region. Initially, the waste has been calcined at 700 ºC for 2 h and then reacted with the following solutions: Na2CO3 and mixture of Na2CO3 + NaOH to 150 ºC with autogenous pressure for 24 h. The raw materials and transformed materials were characterized by XRD, FTIR and SEM. In both studied media, well-crystallized, basic sodalite was the only phase synthesized, while in the literature usually a mixture of zeolites is obtained.
  • Óleos essenciais das folhas de Vernonia Remotiflora e Vernonia Brasiliana: composição química e atividade biológica Artigo

    Maia, Ana Isabel V.; Torres, Maria Conceição M.; Pessoa, Otília Deusdênia L.; Menezes, Jane Eire S. A. de; Costa, Sônia Maria O.; Nogueira, Vanessa Lúcia R.; Melo, Vânia Maria Maciel; Souza, Elnatan B. de; Cavalcante, Maria Gilvânia B.; Albuquerque, Maria Rose Jane R.

    Resumo em Inglês:

    The chemical composition of the essential oils, obtained by hidrodistillation, from leaves of two Vernonia species (V. remotiflora and V. brasiliana), was determined by GC-FID and GC-MS. Both essential oils were predominantly constituted by sesquiterpenes (92.0 - 93.4%). The main constituents of the oil from V. brasilana were (E)-caryophyllene (36.7%), germacrene D (35.5%), and α-humulene (11.7%), while (E)-caryophyllene (42.2%) and bicyclogermacrene (20.0%) were the major ones in the oil from V. remotiflora. Although with moderate activity both oils showed acetylcholinesterase and antibacterial activities.
  • Improvement of genistein content in solid genistein/-cyclodextrin complexes β

    Xavier, Clarissa R.; Silva, Ana Paula C.; Schwingel, Liege C.; Borghetti, Greice S.; Koester, Letícia S.; Mayorga, Paulo; Teixeira, Helder F.; Bassani, Valquiria L.; Lula, Ivana S.; Sinisterra, Rubén D.

    Resumo em Inglês:

    Genistein:β-cyclodextrin complexes with high drug loading (19.22%) were prepared by freeze-drying and characterized by differential scanning calorimetry and hydrogen nuclear magnetic resonance spectroscopy. The spatial configuration of the complex was proposed by means of 2D-NOESY experiment combined with molecular modeling. According to the results obtained, the interaction of genistein with β -cyclodextrin in a 1:1 complex is supposed to occur mainly through the insertion of the guest A-ring in cyclodextrin cavity, without rule out the possibility of inclusion through the B-ring, as previously reported in the literature.
  • Desenvolvimento de métodos analíticos para determinação de agrotóxicos em sedimentos por cromatografia gasosa monodimensional e bidimensional abrangente com micro detector de captura de elétrons Artigo

    Silva, Juliana Macedo da; Zini, Cláudia Alcaraz; Caramão, Elina Bastos; Canizares, Ewelin Monica Paturi Navarro; Leal, Karen Alam

    Resumo em Inglês:

    The development of analytical methods for determination of eight pesticides of different chemical classes (trichlorfon, propanil, fipronil, propiconazole, trifloxystrobin, permethrin, difenoconazole and azoxystrobin) in sediments with gas chromatography-micro-electron capture detector (GC/µECD) and comprehensive two-dimensional gas chromatography with micro-electron capture detector (GCxGC/µECD) is described. These methods were applied to real sediment samples, and the best results were obtained using a 5% diphenyl-methylpolysiloxane column for 1D-GC. For GCxGC the same column was employed in the first dimension and a 50%-phenyl-methylpolysiloxane stationary phase was placed in the second dimension. Due to the superior peak capacity and selectivity of GCxGC, interfering matrix peaks were separated from analytes, showing a better performance of GCxGC.
  • Processamento e caracterização de espumas vitrocerâmicas do sistema sncp (Sio2-Na2o-Cao-P2 O5) Artigo

    Mundstock, Karoline Bastos; Moraes, Elizangela Guzi de; Hotza, Dachamir; Oliveira, Antonio Pedro Novaes de; Siligardi, Cristina; Rogero, Sizue Ota

    Resumo em Inglês:

    Glass-ceramics foams prepared from glasses of the SiO2-Na2O-CaO-P2O5 by replication process were obtained and characterized in terms of their chemical and physical properties by X-ray fluorescence, X-ray diffraction, laser diffraction, thermal analysis, density, mechanical strength, microstructural and cytotoxic analysis. The results showed that it is possible to produce glass-ceramic foams by the replication method with optimized properties but cytotoxic analysis indicates that the glass-ceramic foams are not bioactive materials. Mechanical strength values varying from 0.5 to 1.0 MPa and from 0.8 to 2.3 MPa were reached for mean particle sizes of 10 and 6 µm, respectively.
  • Alteração do caráter hidrofílico de filmes de quitosana por tratamento de plasma de HMDS Artigo

    Assis, Odilio B. G.

    Resumo em Inglês:

    Alteration in hydrophilicity feature of chitosan films by hexamethyldisilazane (HMDS) cold-plasma treatment is evaluated. All treated films were colorless and transparent with no apparent textural changes. The effect on surfaces was characterized through contact angle measurements, degree of swelling and water vapor permeation. A significant reduction in all of the hydrophilicity parameters was observed. It is assumed that the HMDS treatment forms nonpolar silicone type structures. The goal is to investigate the formation of a stable hydrophobic barrier in order to increase the chitosan films usefulness in packaging applications.
  • Salinidade em petróleo bruto: otimização de metodologia e proposta de um novo método para extração de sais em petróleo Artigo

    Morigaki, Milton K.; Chimin, Roberta Q. F.; Sad, Cristina M. dos S.; Filgueiras, Paulo R.; Castro, Eustaquio V. R. de; Dias, Júlio C. M.

    Resumo em Inglês:

    The quantity of salts in the crude oils depends on the origin and of the wells production and these salts cause several problems during the transport and the process of refine as corrosions, incrustations and deactivation of the employed catalysts in the refineries. In this study were implemented changes for improvements in the execution of ASTM D 6470 method and has also developed a new methodology of extraction system of salts using process of mechanical agitation without heating. The results of the optimization produce larger efficiency and safety to the process compared to the traditional ASTM method.
  • Avaliação da contaminação de metais em sedimentos superficiais das praias do lago de Itaipu Artigo

    Belo, Andressa; Quináia, Sueli Pércio; Pletsch, Adelmo Lowe

    Resumo em Inglês:

    This work was performed to evaluate the distribution of metals Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn in the sediment surface in the Itaipu Lake-PR-Brazil. It was also performed to measurement the pH, phosphorus, organic carbon and particle size. In accordance of international criteria of quality of sediment, the results indicate an anthropogenic collaborations since some metals reached an excessive values. The factor of contamination was also used to evaluate the levels of contamination. The levels of Cu and Pb indicate a moderate contamination, so that it's possible to do harm to the balance of the ecosystem studied.
  • Emissão de óxido nitroso de estação de tratamento de esgoto de lodos ativados por aeração prolongada - estudo preliminar Artigo

    Brotto, Ariane Coelho; Kligerman, Débora Cynamon; Piccoli, Andrezza de Souza; de Mello, William Zamboni

    Resumo em Inglês:

    Nitrous oxide emissions from an activated sludge plant which serves a research institute in Rio de Janeiro city were estimated from six unit processes (grit tank, sand trap, aeration tank, secondary settling tank, sludge recirculation line and aerobic digester sludge tank) and also from the plant effluent. Total estimated annual flux was 3.2 x 10(4) g N2O yr-1 of which about 90% was from the aeration tank. Emission factors estimated from population served, wastewater flow and nitrogen load (conversion ratio) were 13 g N2O person-1 yr-1, 9.0 x 10-5 g N2O Lwastewater-1 and 0.14%.
  • Flow injection green method for the quantitative analysis of ketoconazole in pharmaceutical preparations

    Scatolin, Felipe; Tubino, Matthieu; Vila, Marta Maria Duarte Carvalho

    Resumo em Inglês:

    A flow injection method for the quantitative analysis of ketoconazole in tablets, based on the reaction with iron (III) ions, is presented. Ketoconazole forms a red complex with iron ions in an acid medium, with maximum absorbance at 495 nm. The detection limit was estimated to be 1×10--4 mol L-1; the quantitation limit is about 3×10--4 mol L-1 and approximately 30 determinations can be performed in an hour. The results were compared with those obtained with a reference HPLC method. Statistical comparisons were done using the Student's t procedure and the F test. Complete agreement was found at the 0.95 significance level between the proposed flow injection and the HPLC procedures. The two methods present similar precision, i.e., for HPLC the mean relative standard deviation was ca. 1.2% and for FIA ca. 1.6%.
  • Otimizaçâo das condições de preparação de eletrodos à base de carbono cerâmico utilizando-se planejamento fatorial Artigo

    Skeika, Tatiane; Pessoa, Christiana; Fujiwara, Sergio Toshio; Nagata, Noemi

    Resumo em Inglês:

    Different parameters of carbon ceramic electrodes (CCE) preparation, such as type of precursor, carbon material, catalyst amount, among others, significantly influence the morphological properties and consequently their electrochemical responses. This paper describes a 2³ factorial design (2 factors and 3 levels with central point replicates), which the factors analyzed were catalyst amount (HCl 12 mol L-1), graphite/precursor ratio, and precursor type (TEOS - tetraethoxysilane and MTMOS - methyltrimetoxysilane). The design resulted in a significant third order interaction for peak current values (Ipa) and a second order interaction for potential difference (ΔE), between thefactors studied, which could not be observed when using an univariated study.
  • Perfil químico de cultivares de feijão (phaseolus vulgaris) pela técnica de high resolution magic angle spinning (HR-MAS) Artigo

    Lião, Luciano Morais; Choze, Rafael; Cavalcante, Pedro Paulo Araujo; Santos, Suzana da Costa; Ferri, Pedro Henrique; Ferreira, Antonio Gilberto

    Resumo em Inglês:

    The application of one-dimensional proton high-resolution magic angle spinning (¹H HR-MAS) NMR combined with a typical advantages of solid and liquid-state NMR techniques was used as input variables for the multivariate statistical analysis. In this paper, different cultivars of beans (Phaseolus vulgaris) developed and in development by Embrapa - Arroz e Feijão were analyzed by ¹H HR-MAS, which have been demonstrated to be a valuable tool in its differentiation according chemical composition and avoid the manipulation of the samples as used in other techniques.
  • Estrogênios em águas naturais e tratadas da região de Jaboticabal - São Paulo Artigo

    Lopes, Laudicéia G.; Marchi, Mary R. R.; Souza, João B. G.; Moura, José A.; Lorenzon, Cintia S.; Cruz, Claudinei; Amaral, Luiz A.

    Resumo em Inglês:

    The aim of this work was to analyze 17 β estradiol and estrone, natural estrogenic hormones present in domestic effluents and animal excreta, in the public water supply system of Jaboticabal, SP. The results have shown the presence of estrogens in 22% of the samples in concentrations from 6,8 ng L-1 (treated water) to 30,6 ng L-1 (riverhead) for 17 β estradiol and 600 ng L-1 of estrone (stream), respectively. We concluded that animal wastes, discharges from the wastewater treatment station, and discharges of domestic effluent without treatment from rural proprieties were probably the cause of this contamination.
  • Bioaccumulation of metals in aquatic insects of streams located in areas with sugar cane cultivation

    Corbi, Juliano José; Froehlich, Claudio Gilberto; Strixino, Susana Trivinho; Santos, Ademir dos

    Resumo em Inglês:

    Streams located in areas of sugar cane cultivation receive elevated concentrations of metal ions from soils of adjacent areas. The accumulation of metals in the sediments results in environmental problems and leads to bioaccumulation of metal ions by the aquatic organisms. In the present study, bioaccumulation of the metals ions Al, Cd, Cr, Cu, Fe, Mg, Mn and Zn in aquatic insects in streams impacted by the sugar cane was evaluated. The results pointed out that the insects were contaminated by the sediment and that the collector organisms as Chironomus species accumulated higher concentration of metals than the predator organisms.
  • Determinação de sibutramina em formas farmacêuticas através de espectroscopia no infravermelho com refletância difusa e métodos de calibração multivariada Artigo

    Maluf, Daniela Florencio; Pontarolo, Roberto; Cordeiro, Gilcélia A.; Nagata, Noemi; Peralta-Zamora, Patricio

    Resumo em Inglês:

    The goal of this work is the development and validation of an analytical method for fast quantification of sibutramine in pharmaceutical formulations, using diffuse reflectance infrared spectroscopy and partial least square regression. The multivariate model was elaborated from 22 mixtures containing sibutramine and excipients (lactose, microcrystalline cellulose, colloidal silicon dioxide and magnesium stearate) and using fragmented (750-1150/ 1350-1500/ 1850-1950/ 2600-2900 cm-1) and smoothing spectral data. Using 10 latent variables, excellent predictive capacity were observed in the calibration (n=20, RMSEC=0.004, R= 0.999) and external validation (n=5, RMSEC= 9.36, R=0.999) phases. In the analysis of synthetic mixtures the precision (SD=3,47%) was compatible with the rules of the Agencia Nacional de Vigilância Sanitária (ANVISA-Brazil). In the analysis of commercial drugs good agreement was observed between spectroscopic and chromatographic methods.
  • Estudio preliminar sobre la determinación de elementos traza en cervezas venezolanas por ICP-OES

    Marcano, Eunice; Gómez, Clara; Benzo, Zully; Laine, Jorge

    Resumo em Inglês:

    The levels of several chemical elements were determined simultaneously in ten different beers of the Venezuelan market by ICP-OES. With the exception of chromium, beer does not provide important amounts of nutritional oligoelements. The average chromium content found (33 µg/L) is higher than one reported for USA's beer (10 µg/L) but smaller than another reported for Brazilian beer (66 µg/L). The average percentage of chromium RDA by beer consumption found for Venezuela (6.3%) is similar to that reported for Belgium (5%). Regarding toxic elements, one of the samples contained an elevated amount of aluminium, probably dissolved from the aluminium can.
  • Estudio químico y evaluación de la actividad antifouling del octocoral caribeño Eunicea laciniata

    Silva, Carmen Tatiana Cuadrado; Hernández, Leonardo Castellanos; Reyes, Oscar Eduardo Osorno; Rodríguez, Freddy Alejandro Ramos; Beltrán, Carmenza Duque; Hegedus, Mónica Puyana

    Resumo em Inglês:

    The bioassay guided purification of the octocoral Eunicea laciniata organic extract, collected at Santa Marta bay, Colombia, allowed the isolation of the new compound (-)-3β-pregna-5,20-dienyl-β-D-arabinopyranoside (1), along with the known compounds 1(S*),11(R*)-dolabell-3(E),7(E),12(18)-triene (2), 13-keto-1(S),11(R)-dolabell-3(E ),7(E),12(18)-triene (3), cholest- 5,22-dien-3β-ol (4), cholesterol (5), y brassicasterol (6). The structure and absolute configuration of 1 was determined on based spectroscopic analyses (NMR and CD). The extract showed antifouling activity against five strains of marine bacteria associated to heavy fouled surfaces. Also showed activity against the cypris of the cosmopolitan barnacle Balanus amphitrite, and low toxicity in Artemia salina test.
  • Estudo fitoquímico de espécimens cultivados de cumaru (Amburana cearensis A. C. Smith) Artigo

    Canuto, Kirley Marques; Silveira, Edilberto Rocha; Bezerra, Antonio Marcos Esmeraldo

    Resumo em Inglês:

    Due to the threat of extinction of Amburana cearensis, a tree of medicinal importance for the Northeastern Brazil, a phytochemical analysis was performed with specimens obtained by seed germination. Ten compounds were isolated and identified by spectroscopic methods and comparison with literature data. p-Hydroxybenzoic acid, ayapin, (E/Z)-melilotosides are being reported for the first time for the genus, besides coumarin, isokaempferide, vanillic acid, protocatechuic acid, amburosides A and B which have already been found in the trunk bark. Based on physical and NMR spectroscopy evidences the structures of several melilotosides already described in the literature have been suggested to be revised.
  • Antibióticos: importância terapêutica e perspectivas para a descoberta e desenvolvimento de novos agentes Revisão

    Guimarães, Denise Oliveira; Momesso, Luciano da Silva; Pupo, Mônica Tallarico

    Resumo em Inglês:

    There is a continuous need for antibiotics, mainly with new mechanisms of action, since infectious diseases represent the second major cause of death in the world and bacteria resistance levels are high. This review describes the contribution of microbial natural products for the development of the major antibiotic classes, the mechanisms of action of current antibiotics, some modern approaches involving genetic tools for the discovery and development of new antibiotics from microbial products and antibiotics in clinical trials.
  • Fulereno[C60]: química e aplicações Revisão

    Santos, Leandro José dos; Rocha, Guilherme Pereira; Alves, Rosemeire Brondi; Freitas, Rossimiriam Pereira de

    Resumo em Inglês:

    Fullerene chemistry has become a very active research field in the two last decades, largely because of the exceptional properties of the C60 molecule and the variety of fullerene derivatives that appear to be possible. In this review, a general analysis of fullerene C60 reactivity is performed. The principal methods for the covalent modification of this fascinating carbon cage are presented. The prospects of using fullerene derivatives as medicinal drugs and photoactive materials in light converting devices are demonstrated.
  • Propriedades químico-quânticas empregadas em estudos das relações estrutura-atividade Revisão

    Arroio, Agnaldo; Honório, Káthia M.; Silva, Albérico B. F. da

    Resumo em Inglês:

    In this work we show that structure-activity relationship studies are of great importance in modern chemistry and biochemistry. In order to obtain a significant correlation, it is crucial that appropriate descriptors be employed. Thus, quantum chemical calculations are an attractive source of new molecular descriptors which can, in principle, express all the electronic and geometric properties of molecules and their interactions with the biological receptor.
  • Tetraciclinas e glicilciclinas: uma visão geral Revisão

    Pereira-Maia, Elene Cristina; Silva, Priscila Pereira; Almeida, Wagner Batista de; Santos, Hélio Ferreira dos; Marcial, Bruna Luana; Ruggiero, Reinaldo; Guerra, Wendell

    Resumo em Inglês:

    Tetracyclines exhibits activity to a broad range of Gram-negative and Gram-positive bacteria and this fact allied to the low toxicity, low cost, and the advantage of administration by oral route led to their indiscriminate use, which caused the appearance of bacterial resistance to these agents, wich has restricted its clinical utility, though new applications have emerged. On the other hand, the glycylcyclines, semi-synthetic products are similar to tetracyclines, which are active against many bacteria resistant to tetracycline and other classes of antibiotics. The purpose of this paper is to give an overview of this important class of antibiotics focusing on its coordination chemistry and possible applications.
  • Aplicação de α-oxoceteno ditiocetais em síntese orgânica Revisão

    Siqueira, Geonir M.; Neuenfeldt, Patrícia D.; Duarte, Anaí; Bretanha, Lizandra C.; Freitag, Rogério A.; Cunico, Wilson

    Resumo em Inglês:

    The synthesis and reactivity of α-oxoketenes dithioacetals (S,S-acetals), general structure [(R¹C=OC(R²)=C(SR³)(SR4)], are reported. We also showed the application of S,S acetals as synthons for efficient synthesis of isoxazoles, pyrazoles, indazoles, thiophenes, dithiol thiones, pyridines, pyrimidines and other heterocycles. This work aims to review the importance of α-oxoketenes dithioacetals in organic chemistry during the past few years.
  • Marcadores metálicos como avaliação do impacto crônico de emissões petroquímicas em zona urbana Nota Técnica

    Garcia, Felipe Azevedo de Paula; Mirlean, Nicolai; Baisch, Paulo Roberto

    Resumo em Inglês:

    Nickel and vanadium were tested as tracers of oil refinery emission distribution in populated area of Rio Grande-RS. The anomalies of these elements in surface soil are considered a long-term reflection of the emissions in low atmosphere. The spatial distribution of Ni and V in the soil corresponded to the pattern of local winds. The threshold of 1.5 backgrounds of these metals markedly outlined the area of petrochemical emissions. Anomalies of Ni and V in surface soil have a rather different configuration in comparison with other metal tracers of urban impact: Cd, Cu, Pb and Zn.
  • Desenvolvimento de um titulador baseado na contagem de gotas Nota Técnica

    Oliveira, André Fernando; Lima, Alexandre Correa; Silva, Astréa F. Souza; Almeida, Rodrigo de Maio

    Resumo em Inglês:

    TitDrop II, a practice low-cost titrator based on drop counting is proposed. A microcomputer counts drops in an opto-switch and it receives pH values from a commercial pHmeter with RS-232 serial port. The volume of drops must kept constant and the amount of base in each drop is obtained by standardization in the titrator. A linear behavior between height of reservoir of titrant and drop frequency was observed, but there is no influence of low height on drop volume. Acetic acidity in samples of vinager was compared with volumetric titration, and deviation between -2.6 to 3.9% was observed.
  • Identificação química da clorofenilpiperazina (CPP) em comprimidos apreendidos Nota Técnica

    Lanaro, Rafael; Costa, José Luiz; Zanolli Filho, Luiz Antonio; Cazenave, Silvia Oliveira Santos

    Resumo em Inglês:

    Designer drug is a term used to describe psychoactive drugs of abuse which are usually synthesized by modifying the molecular structures of existing drugs of abuse. The term gained widespread popularity when MDMA (ecstasy) experienced a popularity boom in the mid 1980´s. In Brazil, designer drugs seizures have increased in the last few years, and actually tablets with unknown psychoactive compounds began to be forwarded to the Forensic Laboratories. This work describes the analytical assays that were performed to identify the chlorophenylpiperazine, a psychoactive substance first time identified in seized tablets in Sao Paulo state.
  • Reaproveitamento de óxidos de manganês de pilhas descartadas para eletrocatálise da reação de redução de oxigênio em meio básico Nota Técnica

    Rascio, Daniel C.; Souza, Rodrigo F. B. De; Teixeira Neto, Érico; Suffredini, Hugo B.; Santos, Mauro C.; Calegaro, Marcelo L.

    Resumo em Inglês:

    The oxygen reduction reaction was studied in alkaline media using manganese oxides obtained from spent batteries as electrocatalysts. Three processes were used to recover manganese oxides from spent batteries. The particles obtained were in the range from 8 to 11 nm. The electrochemical experiments indicated a good electrocatalytic activity toward oxygen reduction using the different samples and showing approximately a direct transference of 4 electrons during the process. Even though all the processes were efficient, the best result was observed for the prepared sample using reactants of low cost.
  • Caracterização de contaminantes presentes em sistemas de tratamento de esgotos, por cromatografia líquida acoplada à espectrometria de massas tandem em alta resolução Nota Técnica

    Leite, Gustavo de Sousa; Afonso, Robson José de Cássia Franco; Aquino, Sérgio Francisco de

    Resumo em Inglês:

    This work shows results on the characterization, by liquid chromatography coupled to high resolution tandem mass spectrometry (LC-IT-TOF-MS) with electrospray ionization, of organic compounds present in raw and treated effluents from a combined sewage treatment systems (upflow anaerobic sludge blanket-trickling filter). The sewage samples were prepared by C18 solid phase extraction and the spectra obtained from the various extracts were submitted to principal component analysis to evaluate their pattern and identify the major deprotonated species. Some target compounds were submitted to semiquantitative analysis, using phenolphtalein as internal standard. The results showed the anaerobic step had little impact on the removal of anionic surfactants (LAS), fatty acids, and some contaminantes such as bisphenol A and bezafibrate, whereas the aerobic post-treatment was very efficient in removing these organics.
  • Development of a simple, rapid and validated spectrophotometric method for nitazoxanide in pharmaceutical formulations and comparison with HPLC

    Malesuik, Marcelo Donadel; Paim, Clésio Soldatelli; Schapoval, Elfrides Eva Scherman; Steppe, Martin

    Resumo em Inglês:

    A rapid, economical, reproducible, and simple direct spectrophotometric method was developed and validated for the assay of nitazoxanide in pharmaceutical formulations. Nitazoxanide concentration was estimated in water at 345 nm and pH 4.5. The method was suitable and validated for specificity, linearity, precision, and accuracy. There was no interference of the excipients in the determination of the active pharmaceutical ingredient. The proposed method was successfully applied in the determination of nitazoxanide in coated tablets and in powders for oral suspension. This method was compared to a previously developed and validated method for liquid chromatography to the same drug. There was no significative difference between these methods for nitazoxanide quantitation.
  • Obtenção do 2-etóxi-2-metilpropano grau analítico a partir do produto comercial Nota Técnica

    Venturi, Vanessa; Cataluña, Renato

    Resumo em Inglês:

    Ethyl tert-butyl ether (ETBE) is produced by commercial processes to a purity of up to 96%. In recent years, several companies have started to produce ETBE, increasing the demand for standards with higher grades of purity in the area of production control and final product certification. The present work involved the development of a purification protocol for obtaining high purity ETBE from the commercial product used in the formulation of automotive gasolines, using a spinning band distillation column. The ETBE thus produced showed a purity of over 99.5%, its main contaminant being its isomer, ethyl-sec-butyl ether (ESBE).
  • Desenvolvimento e validação de um método analítico simples e rápido por espectroscopia UV para quantificação de aciclovir em matrizes hidrofílicas de liberação prolongada Nota Técnica

    Barboza, Fernanda Malaquias; Vecchia, Débora Dalla; Pereira, Airton Vicente; Stulzer, Hellen Karine; Silva, Marcos Antonio Segatto

    Resumo em Inglês:

    This work reports the validation of an analytical UV spectrophotometric method to assay acyclovir in hydrophilic matrices (assay and dissolution studies). The method was linear in the range between 2.5-20 µg mL-1, presenting a good correlation coefficient ( r = 0,9999). Precision and accuracy analysis showed low relative standart deviation (< 2.0 %) and a good recoveries percentual (98.9-100 %). The procedure was linear, accurate, and robust. The method is simple and cheap. It does not use polluting reagents and can be applied in dissolution studies, being an adequate alternative to assay acyclovir in hydrophilic matrices tablets.
  • Estudio teórico de la isomerización del ácido maleico en ácido fumárico: un enfoque basado en el concepto de superficie de energía potencial

    Ugarte, Ricardo; Salgado, Guillermo; Martinez, Rolando; Navarrete, José

    Resumo em Inglês:

    A comparative study based on potential energy surfaces (PES) of 2-butanedioic and hypothetic 2-butanedioic/HCl acids is useful for understanding the maleic acid isomerization. The PES enables locating conformers of minimum energy, intermediates of reactions and transition states. From contour diagrams, a set of possible reaction paths are depicted interconnecting the proposed structures. The study was carried out in absentia and in the presence of the catalyst (HCl), using an solvatation model provided by the Gaussian software package. Clearly, the effect of HCl is given by new reaction paths with lower energetic barriers in relation to the reaction without catalyzing.
  • Determinação de ácido acéttico em amostra de vinagre adulterada com ácido clorídrico - um experimento integrado de titulação potenciométrica e condutométrica Educação

    Martins, José Vinicius; Souza, Ana Paula Ruas de; Salles, Maiara Oliveira; Serrano, Silvia Helena Pires

    Resumo em Inglês:

    The determination of acetic acid in vinegar adulterated sample using simultaneous potentiometric and condutometric titrations was used as an example of integrated experiment in instrumental analysis. An Excel® spreadsheet, which allows the entry of simultaneous data and the construction of the superimposed experimental curves (condutometric, potentiometric, first and second derivative potentiometric curve and, distribution diagrama of the acetic species as function of pH), was used as powerful tool to discuss the fundamental concepts involved in each technique and choose the best of them to quantify, without mutual interference, H3CCOOH and HCl in vinegar adulterated sample.
  • Uma métrica gráfica para avaliação holística da verdura de reacções laboratoriais - "Estrela Verde" Educação

    Ribeiro, M. Gabriela T. C.; Costa, Dominique A.; Machado, Adélio A. S. C.

    Resumo em Inglês:

    A new semi-quantitative metrics, Green Star (GS), for evaluation of the global greenishness of chemical reactions used in teaching laboratories has been developed. Its aim is to help choosing the more acceptable reactions for implementing Green Chemistry (GC) and to identify suitable modifications of reaction protocols to improve the greenishness of chemistry. GS considers globally all the Twelve Principles of GC. To illustrate its construction, the tetraamminecopper(II) sulfate monohydrate laboratory synthesis, performed under several sets of conditions to pursue greenishness, is presented. A comparative study with other GC metrics showed the advantages of GS and that it accomplishes its purpose.
  • Produção científica e formação de recursos humanos na área de bioquímica em instituições federais do Rio Grande do Sul: fomento estadual Assuntos Gerais

    Berti, Luciana Calabró; Oliveira, Diogo L.; Souza, Diogo O.; Wofchuk, Susana T.

    Resumo em Inglês:

    Brazilian scientific production in Biochemistry is growing impressively fast, and Rio Grande do Sul is outstanding in that context. This study aims to outline the state's scientific research profile, given its prominent position in the national scenario. Hence, researchers, laboratories, development of human resources and investments by Foundation for the Support to Research in the State of Rio Grande do Sul (FAPERGS) were identified and mapped. We observed that amount of financial support by FAPERGS decreases in last years. Therefore, there is the necessity to reestablish some of FAPERGS's programs, as well as to increase financial support to Biochemistry departments.
  • Errata

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