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Química Nova, Volume: 33, Número: 4, Publicado: 2010
  • 33ª Reunião Anual da Sociedade Brasileira de Química Editorial

    Catalani, Luiz Henrique
  • Selective hydrogenation of furfural on Ir/TiO2 catalysts

    Reyes, Patricio; Salinas, Daniela; Campos, Cristian; Oportus, Marcelo; Murcia, Julie; Rojas, Hugo; Borda, Gloria; Fierro, José Luís García

    Resumo em Inglês:

    Titania-supported Ir catalysts were used in the hydrogenation of furfural. Reactions were carried out in a stirred batch type reactor at 0.62MPa and 363K using a 0.10M solution of furfural in a 1:1 mixture n-heptane -ethanol as solvent. Catalysts containing 2 wt% of Ir were reduced in H2 flow at different temperatures in the range 473-773K. The catalysts were characterized by H2 chemisorption, TEM, TPR, TPD of NH3 and XPS. Conversion of furfural is higher at lower reduction temperatures, but leads to byproducts whereas reduction at higher temperatures shows selectivity to furfuryl alcohol close to 100%.
  • Avaliação de biocombustível derivado do bio-óleo obtido por pirólise rápida de biomassa lignocelulósica como aditivo para gasolina Artigo

    Guedes, Carmen Luisa Barbosa; Adão, Daniele Cristina; Quessada, Talita Pedroso; Borsato, Dionísio; Galão, Olívio Fernandes; Di Mauro, Eduardo; Pérez, Juan Miguel Mesa; Rocha, José Dilcio

    Resumo em Inglês:

    A biofuel was prepared from acid aqueous fraction (pH = 2) of bio-oil produced by fast pyrolysis (Bioware Technology) of lignocellulosic biomass (sugar cane residue) and tested in blends (2, 5, 10 e 20% v/v) with gasoline type C (common) marketed in Brazil. The specification tests made in the Refinery President Getúlio Vargas (PETROBRAS) showed increasing in the octane number (MON) and antiknock index (AKI) with reduction in the residue generation during the combustion. The physicochemical characteristics of the biofuel were similar that combustible alcohol allowing its use as gasoline additive.
  • Aplicación de una lengua electrónica voltamétrica para la clasificación de vinos y estudio de correlación con la caracterización química y sensorial

    Arrieta, Álvaro A.; Rodríguez-Méndez, María L.; Saja, José A. De

    Resumo em Inglês:

    This paper presents the analytical application of a novel electronic tongue based on voltammetric sensors array. This device was used in the classification of wines aged in barrels of different origins and toasting levels. Furthermore, a study of correlation between the response of the electronic tongue and the sensory and chemical characterization of samples was carried out. The results were evaluated by applying both principal component analysis and cluster analysis. The samples were clearly classified. Their distribution showed a high correspondence degree with the characteristics of the analyzed wines, it also showed similarity with the classification obtained from organoleptic analysis.
  • Obtaining high purity silica from rice hulls

    Silva Júnior, José da; Cunha, Carlo R. da; Carvalho, Flávio L. S. de; Rodrigues Filho, Ubirajara P.; Oliveira, Paulo R.; Silva, Marcos A. Segatto

    Resumo em Inglês:

    Many routes for extracting silica from rice hulls are based on direct calcining. These methods, though, often produce silica contaminated with inorganic impurities. This work presents the study of a strategy for obtaining silica from rice hulls with a purity level adequate for applications in electronics. The technique is based on two leaching steps, using respectively aqua regia and Piranha solutions, which extract the organic matrix and inorganic impurities. The material was characterized by Fourier-transform infrared spectroscopy (FTIR), powder x-ray diffraction (XRD), x-ray fluorescence (XRF), scanning electron microscopy (SEM), particle size analysis by laser diffraction (LPSA) and thermal analysis.
  • Degradação fotocatalítica do fungicida tebuconazole em solução aquosa Artigo

    Prestes, Thiago de Hermann; Gibbon, Danielle de Oliveira; Lansarin, Marla Azário; Moro, Celso Camilo

    Resumo em Inglês:

    The tebuconazole photocatalytic degradation kinetics was studied in a batch reactor using TiO2 (P25-Degussa) as catalyst and a high pressure mercury lamp. The photolysis, adsorption and irradiation effects in the reaction rate were evaluated. Afterward, the suspension catalyst concentration and initial pH to the maximum reaction rate was determined. It was observed that the reaction rate can be approached by a pseudo-first order, with a maximum kinetics constant at 260 mg L-1catalyst concentration and pH 7.7.
  • Caldensinic acid, a benzoic acid derivative and others compounds from Piper carniconnectivum

    Alves, Harley da Silva; Souza, Maria de Fátima Vanderlei de; Chaves, Maria Célia de Oliveira

    Resumo em Inglês:

    A benzoic acid derivative - caldensinic acid; E-phytyl hexadecanoate; β-sitosterol and stigmasterol mixture and phaeophytin a were isolated from the aerial parts of Piper carniconnectivum. The structures of these compounds were established unambiguously by IR, MS, 1D and 2D NMR analysis.
  • Interferência do acido ascórbico na determinação de açúcares redutores pelo método de Lane e Eynon Artigo

    Tavares, José Torquato de Queiroz; Cardoso, Ricardo Luis; Costa, João Albany; Fadigas, Francisco de Souza; Fonseca, Antônio Augusto

    Resumo em Inglês:

    Two studies, both set up as completely randomized design, in a 5x5 and 7x5 factorial schemes, evaluated the interference of 5 and 7 ascorbic acid concentrations and 5 glucose or 5 sucrose concentrations, respectively, on the determination of total and reducing sugars by Lane and Eynon method. The ascorbic acid reducing power (AARP) over the Fehling liquor interfered in the results of total and reducing sugars. On average the AARP was equivalent to 74.83 and 69.71% of the reducing power of glucose and of hydrolyzed sucrose, respectively. The ascorbic acid was stable in all study conditions.
  • Propriedades eletrônicas, estruturais e constantes elásticas do ZnO Artigo

    Marana, Naiara Letícia; Sambrano, Julio Ricardo; Souza, Aguinaldo Robinson de

    Resumo em Inglês:

    The electronic, structural properties and elastic constants of the wurtzite phase of zinc oxide, ZnO, was investigated using computer simulation at Density Functional Theory level, with B3LYP hybrid functional and Hartree-Fock methodology. The electronic properties as well the band energy was investigated through the analysis of the band structures and density of states (DOS), and the mechanical properties was studied through the calculus of the elastic constants C11, C33, C44, C12 e C13. The results are in good agreement with experimental data found in the literature and in accordance with results obtained by another theoretical methodology.
  • Influence of ni addition to a low-loaded palladium catalyst on the selective hydrogenation of 1-heptyne

    Lederhos, Cecilia R.; Badano, Juan M.; Quiroga, Mónica E.; L'Argentière, Pablo C.; Coloma-Pascual, Fernando

    Resumo em Inglês:

    Semi-hydrogenation of alkynes has industrial and academic relevance on a large scale. To increase the activity, selectivity and lifetime of monometallic catalysts, the development of bimetallic catalysts has been investigated. 1-Heptyne hydrogenation over low-loaded Pd and Ni monometallic and PdNi bimetallic catalysts was studied in liquid phase at mild conditions. XPS results suggest that nickel addition to Pd modifies the electronic state of palladium as nickel loading is increased. Low-loaded Pd catalysts showed the highest selectivities (> 95%). The most active prepared catalyst, PdNi(1%), was more selective than the Lindlar catalyst.
  • Comportamento do mercúrio em perfis de solos do sítio Ilha de Terra-Caxiuanã, Pará Artigo

    Gurjão, Robson da Silva; Lemos, Vanda Porpino; Costa, Marcondes Lima da; Filho, Heronides Adonias Dantas; Dantas, Kelly das Graças Fernandes; Lima, Wivian Thais dos Santos; Kern, Dirse Clara

    Resumo em Inglês:

    Behavior of mercury in soil profiles with archaeological black earth (ABE) and surroundings area (SA) from Sítio Ilha de Terra, Caxiuanã, can provide information on anthropogenic activity of the Amazonian habitat. The samples of ABE and SA soil profiles were submitted to mineralogical chemical (total and sequential) analysis. The data show that the Hg occurs mainly in goethite and kaolinite in the two soil profiles. The highest concentrations of Hg and Fe are observed in the SA profile. These results indicate that the prehistoric human occupation contributed to the decrease of the concentration of Hg in soil ABE from Caxiuanã.
  • Poluição e a densidade de vegetação: BTEX em algumas áreas públicas de Curitiba - PR, Brasil Artigo

    Godoi, Ana Flavia Locateli; Godoi, Ricardo Henrique Moreton; Azevedo, Roosevelt de; Maranho, Leila Teresinha

    Resumo em Inglês:

    The occurrence of benzene, toluene, ethylbenzene, and xylenes (BTEX) in some public areas of Curitiba-PR, Brazil, was evaluated. Their concentrations were then related to the vegetation's density in each area. Average benzene concentrations varied from 3.9 to 6.1 μg m-3, with higher values occurring in poorly dense vegetation areas. For toluene, average concentrations ranged from 6.5 to 7.2 μg m-3. The effect of such pollutants was evaluated by means of a bio indicator, Tillandsia stricta. Variation in total chlorophyll content and in stomatic density were detected in some samples and may be related to the BTEX concentrations found in the studied areas.
  • Efeitos da adição de átomos de Mn na rede do GaN via métodos de estrutura eletrônica Artigo

    Mazini, Melânia Cristina; Sambrano, Julio Ricardo; Cavalheiro, Alberto Adriano; Leite, Douglas Marcel Gonçalves; Silva, José Humberto Dias da

    Resumo em Inglês:

    A computational method to simulate the changes in the electronic structure of Ga1-xMn xN was performed in order to improve the understanding of the indirect contribution of Mn atoms. This periodic quantum-mechanical method is based on density functional theory at B3LYP level. The electronic structures are compared with experimental data of the absorption edge of the GaMnN. It was observed that the indirect influence of Mn through the structural parameters can account for the main part of the band gap variation for materials in the diluted regime (x<0.08), and is still significant for higher compositions (x~0.18).
  • Síntese, caracterização e estudos de interação de um análogo da antitoxina CcdA empregando fluorescência no estado estacionário Artigo

    Cotrim, Camila Aparecida; Garrido, Saulo Santesso; Trovatti, Eliane; Marchetto, Reinaldo

    Resumo em Inglês:

    Toxin-antitoxin (TA) systems contribute to plasmid stability by a mechanism called post-segregational killing. The ccd was the first TA system to be discovered with CcdB being the toxin and CcdA the antitoxin. CcdA, an 8.3 kDa protein, interacts with CcdB (11.7 kDa), preventing the cytotoxic activity of CcdB on the DNA gyrase. As an approach to understanding this interaction, CcdA41, a polypeptide derived from CcdA, was synthesized by solid-phase methodology and its interaction with CcdB was analyzed by steady state fluorescence. CcdA41 formed a stable complex with CcdBET2, a peptide based on CcdB, the more recently described bacterial topoisomerase inhibitor.
  • Steroidal and phenolic compounds from Sidastrum paniculatum (L.) Fryxell and evaluation of cytotoxic and anti-inflammatory activities

    Cavalcante, José Marcílio Sobral; Nogueira, Tiago Bezerra de Sá de Souza; Tomaz, Anna Cláudia de Andrade; Antas e Silva, Davi; Agra, Maria de Fátima; Souza, Maria de Fátima Vanderlei de; Carvalho, Paulo Roberto Cavalcanti; Ramos, Sílvia Rafaelli; Nascimento, Silene Carneiro do; Gonçalves-Silva, Teresinha

    Resumo em Inglês:

    Sidastrum paniculatum (L.) Fryxell belongs to the family Malvaceae and is popularly known as "malva roxa" or "malvavisco". The phytochemical study of the hexane, CHCl3 and EtOAc phases from the crude ethanol extract of S. paniculatum led to the isolation of six compounds: a mixture of β-sitosterol and stigmasterol, 4-methoxy-3-hydroxybenzoic acid, 4-methoxy-3-hydroxybenzaldehyde, N-trans-feruloyltyramine and kaempferol-3-O-β-D-(6''-E-p -coumaroyl) glucoside. The structural identification of the compounds was made on the basis of spectroscopic methods such as IR, ¹H and 13C NMR with the aid of including two-dimensional techniques, besides comparison with literature data. The β-sitosterol and stigmasterol mixture showed a significant anti-inflammatory activity.
  • Poliuretanos elastoméricos obtenidos a partir de aceite de ricino y almidón de yuca original y modificado con anhídrido propiónico: síntesis, propiedades fisicoquímicas y fisicomecánicas

    Valero, Manuel F.; Pulido, Jorge E.; Ramírez, Álvaro; Higuita, Luz E.; Arias, Sandra M.; Gonzáles, Carlos S.; Ruiz, Leonidas J.

    Resumo em Inglês:

    Chemical modification of cassava starch was conducted through an acylation reaction by using pyridine and propionic anhydride to replace the functional groups of starch. Polyurethane elastomers were prepared using suspensions of the mixture obtained from castor oil and yucca starch that was modified by a propionic anhydride reaction. The suspensions were characterized by means of tests based on The Fourier Transform Infrared Spectroscopy and the Hydroxyl Index. The castor oil-AMP suspensions were used for the PU synthesis. The PUs were characterized by their physical-mechanical properties like tension- deformation and Shore A. hardness, thermal gravimetric analysis and swelling test. The density cross-linking of from swelling tests was determined by applying the Flory-Rehner equation.
  • Adsorption of glyphosate in a forest soil: a study using Mössbauer and FT-IR spectroscopy

    Benetoli, Luís Otávio de B.; Santana, Henrique de; Carneiro, Cristine E. A.; Zaia, Dimas A. M.; Ferreira, Ailton S.; Paesano Jr., Andrea; Zaia, Cássia Thaïs B. V.

    Resumo em Inglês:

    We studied the adsorption of glyphosate (GPS) onto soil mineral particles, using FT-IR and Mössbauer spectroscopy. From IR measurements for samples collected under native vegetation of a forest reserve, bands at 1632 and 1407 cm-1 could be attributed to the interaction between the carboxylic group of GPS and structural Al3+ and Fe3+ on the surface of mineral particles; bands at 1075 and 1000 cm-1 were observed only for cultivated soil. Mössbauer spectra for these soils were definitely fitted using a broad central doublet in addition to the magnetic component. This multiple quadrupolar component may be attributed to all non-magnetic Fe3+ contributions, including that of the GPS/Fe3+ complex.
  • Heteropentámeros (etanol)4-agua: estudio estructural y termodinámico

    Mejía, Sol M.; Orrego, Juan F.; Espinal, Juan F.; Mondragón, Fanor

    Resumo em Inglês:

    Stochastic exploration of the potential energy surface of (ethanol)4-water heteropentamers through simulated annealing calculations was used to find probable structures of these clusters. Subsequent geometry optimization with the B3LYP/6-31+G(d) approach of these initial structures led to 13 stable heteropentamers. The strength of the hydrogen bonds of the type O"H-O (primary) and their spatial arrangements seem to be responsible for the geometric preferences and the high stability of these heteropentamers. This result is a consequence of the presence of the cooperative effects among such interactions. There is no significant influence of the secondary hydrogen bonds (C"H-O) on the stability of the heteropentamers.
  • In vitro study of antioxidant and scavenger properties of phenolic compounds from Lychnophora species

    Grael, Cristiane F. F.; Kanashiro, Alexandre; Kabeya, Luciana M.; Jordão, Christiane O.; Takeara, Renata; Gobbo-Neto, Leonardo; Polizello, Ana Cristina M.; Lucisano-Valim, Yara M.; Lopes, Norberto P.; Lopes, João Luis C.

    Resumo em Inglês:

    This paper describes the antioxidant effects of thirteen phenolic compounds isolated from plants of the genus Lychnophora. Two assays were performed to evaluate these effects: a cellular test that measured the luminol-enhanced chemiluminescence produced by neutrophils stimulated with opsonized zymosan and a cell-free test involving horseradish peroxidase-H2O2-luminol. In both assays, the antioxidant activity of the phenolic compounds was dependent on their concentration and chemical structure. Our results suggest that the ability of phenolic compounds from Lychnophora species to scavenge and inhibit the generation of ROS may be a mechanism underlying the anti-inflammatory activity of extracts from Lychnophora spp.
  • Antimycobacterial and cytotoxicity activities of free and liposome-encapsulated 3-(4'-bromo[1,1'-biphenyl-4-yl)-3-(4-bromo-phenyl)-N,N-dimethyl-2-propen-1-amine

    Souza, Ana O. de; Silva, Célio L.; Durán, Nelson; Andrade-Santana, Maria H.

    Resumo em Inglês:

    The antimycobacterial activity of 3-(4'-bromo[1,1'-biphenyl-4-yl)-3-(4-bromo-phenyl)-N,N-dimethyl-2-propen-1-amine (BBAP), free or incorporated in preformed liposomes, on extracellular M. tuberculosis H37Rv was 8 and 25 μM (MIC), respectively. Extracellular antimycobacterial activity was not significantly improved by entrapment of BBAP in liposomes, but there was a 6.1-fold reduction of BBAP cytotoxicity on J774 macrophages. Liposomal BBAP or its free form showed IC50 values of 165 and 27 μM, resulting in a selectivity index (SI=IC50/MIC) of 3.4 and 6.6, respectively. Free BBAP in concentrations from 10 to 80 μM were quite effective in eliminating intracellular M. tuberculosis while liposomal formulation was less effective at these concentrations.
  • Aporphine alkaloids from Ocotea macrophylla (Lauraceae)

    Pabon, Ludy Cristina; Cuca, Luis Enrique

    Resumo em Inglês:

    Four aporphine alkaloids from the wood of Ocotea macrophylla (Lauraceae) were isolated and characterized as (S)-3-methoxy-nordomesticine (1), (S)-N-ethoxycarbonyl-3-methoxy-nordomesticine (2), (S)-N-formyl-3-methoxy-nordomesticine (3) and (S)-N-methoxycarbonyl-3-methoxy-nordomesticine (4); alkaloids 2-4 are being report for the first time. The structure the isolated compounds were determined based on their spectral data and by comparison of their spectral data with values described in literature. The alkaloid fraction and compound 1 showed antifungal activity against Fusarium oxysporum f. sp. lycopersici and also compound 1 showed antimicrobial activity towards Staphylococcus aureus, Enterococcus faecalis as well.
  • Adsorção de Cr(VI) em esferas reticuladas de quitosana: novas correlações cinéticas e termodinâmicas utilizando microcalorimetria isotérmica contínua Artigo

    Silva, Rivaldo Cardoso; Andrade Jr, Marcos Antonio S.; Cestari, Antonio Reinaldo

    Resumo em Inglês:

    The synthesis and characterization of crosslinked chitosan microbeads and their application in the removal of Cr(VI) are described. New kinetic and thermodynamic parameters of Cr(VI) adsorptions processes were found using continuous isothermal calorimetry. All adsorption processes are exothermic in nature. However, a multivariate statistical analysis have pointed out that adsorption enthalpies were affected by important binary interactions of the initial Cr(VI) in solution and temperature. The adsorption energetic data were well fitted to a kinetic exponential model, which have indicated fractionary adsorption kinetic orders.
  • Teores de compostos bioativos em cafés torrados e moídos comerciais Artigo

    Souza, Romilaine Mansano Nicolau de; Canuto, Gisele André Baptista; Dias, Rafael Carlos Eloy; Benassi, Marta de Toledo

    Resumo em Inglês:

    The amounts of nicotinic acid, trigonelline, 5-CQA, caffeine, kahweol and cafestol in 38 commercial roasted coffees ranged from 0.02 to 0.04; 0.22 to 0.96; 0.14 to 1.20; 1.00 to 2.02; 0.10 to 0.80 and 0.25 to 0.55 g/100 g, respectively. Evaluation of color and content of thermo-labile compounds indicated similarity in roasting degree. Differences in the levels of diterpenes and caffeine, components less influenced by the roasting degree, could be mainly explained by the species used (arabica and robusta). Gourmet coffees showed high concentrations of diterpenes, trigonelline and 5-CQA and low levels of caffeine, indicating high proportion of arabica coffee.
  • Determinacion de la bioactividad y la resistencia a la compresion de bloques de Poliapatita

    Fernández, Haney Castro; Lozano, Oscar E. Ledea

    Resumo em Inglês:

    Poliapatita® is a composite in study formed by HAP-200®, CaCO3 and POVIAc®. The aims of this work were the determination of the bioactivity and the compression resistance (CR) of biomaterial. The composite was put in contact with a Simulated Body Fluid (28 days at 37 ºC) to evaluate the formation of an superficial apatite layer similar to the bone mineral composition; and to see how diminished the CR in conditions similar to implantation. The bioactivity was evaluated mainly by Scanning Electron Microscopy, Energy-dispersive X-ray Spectroscopy. The composite studied was bioactive and fulfills the requierement of CR asked by ISO 13779-1:2001.
  • Propriedades reológicas e efeito da adição de sal na viscosidade de exopolissacarídeos produzidos por bactérias do gênero Rhizobium Artigo

    Aranda-Selverio, Gabriel; Penna, Ana Lúcia Barretto; Campos-Sás, Luciana Frizarin; Santos Junior, Osvaldo dos; Vasconcelos, Ana Flora Dalberto; Silva, Maria de Lourdes Corradi da; Lemos, Eliana Gertrudes Macedo; Campanharo, João Carlos; Silveira, Joana Léa Meira

    Resumo em Inglês:

    Viscosity of some polysaccharide solutions supports that these molecules can be applied in food sectors. Four exopolysaccharides (R1, R2, R3, R4) produced by different Rhizobium strains were selected. Sugar composition and differences in the uronic acid contents suggests that chemical structure of these molecules can vary when different culture conditions and strains are analyzed. The Power Law was the rheological model used to represent the experimental data of shear stress versus shear rate. All exopolysaccharides showed non-Newtonian behavior, with pseudoplastic characteristics. R1, R2 and R4 showed a slight increase in viscosity in the presence of 0,2 M NaCl.
  • Chemical constituents of Salacia elliptica (Celastraceae)

    Duarte, Lucienir Pains; Figueiredo, Rute Cunha; Sousa, Grasiely Faria de; Soares, Débora Barbosa da Silva; Rodrigues, Salomão Bento Vasconcelos; Silva, Fernando César; Silva, Grácia Divina de Fátima; Vieira Filho, Sidney Augusto

    Resumo em Inglês:

    The chemical investigation of Salacia elliptica allowed to the isolation of 20 constituents: two polyols, one xanthone, a mixture of long chain hydrocarbons, one carboxylic acid, one polymer, two steroidal compounds, one aromatic ester and eleven pentacyclic triterpenes. These triterpenes include 3β-stearyloxy-oleanane, 3β-stearyloxy-ursane, one seco-friedelane, and eight compounds of the friedelane serie. The chemical structure and the relative configuration of a new triterpene 1,3-dioxo-16α-hydroxyfriedelane (15) were established through ¹H and 13C NMR including 2D experiments (HMBC, HMQC, COSY and NOESY) and herein reported for the first time.
  • comparação entre processos em SHF e em SSF de bagaço de cana-de-açúcar para a produção de etanol por Saccharomyces cerevisiae Artigo

    Santos, Julliana Ribeiro Alves dos; Souto-Maior, Ana Maria; Gouveia, Ester Ribeiro; Martín, Carlos

    Resumo em Inglês:

    In this work, four different process configurations, including three simultaneous saccharification and fermentation (SSF) schemes and one separate hydrolysis and fermentation (SHF) scheme, were compared, at 8% water-insoluble solids, regarding ethanol production from steam-pretreated and alkali-delignified sugar cane bagasse. Two configurations included a 16 h lasting enzymatic presaccharification prior to SSF, and the third one was a classical SSF without presaccharification. Cellulose conversion was higher for the delignified bagasse, and higher in SSF experiments than in SHF. The highest cellulose-to-ethanol conversion (around 60% in 24 h) and maximum ethanol volumetric productivities (0.29-0.30 g/L.h) were achieved in the presaccharification-assisted SSF.
  • Influência dos constituintes químicos dos extratos de diferentes matrizes na resposta cromatográfica de agrotóxicos Artigo

    Pinho, Gevany Paulino de; Silvério, Flaviano Oliveira; Neves, Antônio Augusto; Queiroz, Maria Eliana L. R.; Starling, Maria Antônia V. M.

    Resumo em Inglês:

    Multiresidue methods for pesticides monitoring by GC are commonly employed, however, it is well known that the presence of compounds of the matrix introduces errors during the quantiûcation. The main consequence of matrix effect is an increasing or decreasing analyte signal after the GC saturation with extracts of matrix. In this paper, the influence of constituents of nine matrices on the quantification of the four pesticides by GC-ECD was studied. Variation of signal was evaluated by PCA and HCA, and results showed that the constituents of tomato increased the signal (until 300%), while extracts of apple decreased (until -20%). Variation the analyte signal in the presence of the matrix in respect to the same analyte in solvent (standard solution) also was observed, mainly for liver extract (until 270%).
  • Determinação espectrofotométrica de cefalexina em formulações farmacêuticas explorando a sua reação de transferência de carga com a quinalizarina Artigo

    Paula, Carlos Eduardo R. de; Almeida, Vanessa G. K.; Cassella, Ricardo J.

    Resumo em Inglês:

    This work proposes a new simple and fast spectrophotometric method for cephalexin determination in pharmaceutical formulations. The method is based on the charge transfer reaction between cephalexin and quinalizarin in dimethylsulfoxide medium. Several analytical parameters related to the system were optimized and the reaction was characterized in terms of stoichiometry. Also, association constant and apparent molar absorptivity of the product were determined. The method presented a limit of detection of 0.46 mg L-1 and a quantification limit of 1.5 mg L-1. It was successfully applied in the determination of cephalexin in two samples of commercial pharmaceutical formulations.
  • Alteração da atividade enzimática em organismos aquáticos por poluentes de origem agrícola: uma abordagem geral e sobre a suscetibilidade da fosfatase ácida Revisão

    Jonsson, Claudio Martín; Aoyama, Hiroshi

    Resumo em Inglês:

    The input of agrochemicals in the aquatic compartment can results in biochemical injuries for living organisms. In this context, the knowledge of alterations of enzymatic activities due the presence of agriculture pollutants contributes for the elucidation of the mechanisms of toxicity, implementation of economic methods for monitoring purposes and establishment of maximum allowed concentrations. In the present work, the above considerations are discussed, and data concerning changes in enzymatic function by pesticides and fertilizer contaminants are reviewed. Also, we focused on the acid phosphatase due its susceptibility to several pollutants and diversity in cellular functions.
  • Aplicação de ciclodextrinas em processos têxteis Revisão

    Andreaus, Jürgen; Dalmolin, Mara C.; Oliveira Junior, Iguatemy B. de; Barcellos, Ivonete O.

    Resumo em Inglês:

    Cyclodextrins (CDs) are water soluble cyclic sugars with a hydrophobic nanometric cavity that permits the formation of host/guest inclusion complexes with a large variety of molecules, alternating their physical-chemical properties. In the present review CD research related to the processing of textiles is revised and discussed. CDs may function as encapsulating, dispersing and levelling agents in the dyeing and washing of textiles. Furthermore they may be anchored to polymers and textile fibers in order to impart special properties such as odor reduction, UV protection or for the controlled release of perfumes, aromas, mosquito repellents or substances with therapeutical effects.
  • Propriedades dinâmicas de fluidos por simulação computacional: métodos híbridos atomístico-contínuo Revisão

    Costa, Luciano T.; Ribeiro, Mauro C. C.

    Resumo em Inglês:

    Computational methods for the calculation of dynamical properties of fluids might consider the system as a continuum or as an assembly of molecules. Molecular dynamics (MD) simulation includes molecular resolution, whereas computational fluid dynamics (CFD) considers the fluid as a continuum. This work provides a review of hybrid methods MD/CFD recently proposed in the literature. Theoretical foundations, basic approaches of computational methods, and dynamical properties typically calculated by MD and CFD are first presented in order to appreciate the similarities and differences between these two methods. Then, methods for coupling MD and CFD, and applications of hybrid simulations MD/CFD, are presented.
  • Possibilidades e limitações no uso da temperatura em cromatografia líquida de fase reversa Revisão

    Borges, Endler Marcel; Bottoli, Carla B. G.; Collins, Carol.H.

    Resumo em Inglês:

    High-temperature liquid chromatography (HTLC) is a technique that presents a series of advantages in liquid phase separations, such as: reduced analysis time, reduced pressure drop, reduced asymmetry factors, modified retentions, controlled selectivities, better efficiencies and improved detectivities, as well as permitting green chromatography. The practical limitations that relate to instrumentation and to stationary phase instability are being resolved and this technique is now ready to be applied for routine determinations.
  • Supressão das anomalias de fase e batimentos laterais em espectros de RMN 13c obtidos com a sequência de precessão livre no estado estacionário Nota Técnica

    Santos, Poliana Macedo dos; Souza, André Alves de; Colnago, Luiz Alberto

    Resumo em Inglês:

    The Steady-State Free Precession (SSFP) sequence has been widely used in low-field and low-resolution imaging NMR experiments to increase the signal-to-noise ratio (s/n) of the signals. Here, we analyzed the Scrambled Steady State - SSS and Unscrambled Steady State - USS sequences to suppress phase anomalies and sidebands of the 13C NMR spectrum acquired in the SSFP regime. The results showed that the application of the USS sequence allowed a uniform distribution of the time interval between pulses (Tp), in the established time range, allowing a greater suppression of phase anomalies and sidebands, when compared with the SSS sequence.
  • Análise de compostos sulfurados em efluentes gasosos de refinaria de petróleo Nota Técnica

    Afonso, Júlio Carlos; Pereira, Kátia da Silva

    Resumo em Inglês:

    This work discusses an analytical procedure for analysis of sulfur compounds in treated petroleum refinery gaseous effluents using a sulfur chemiluminescence detector with dual plasma burner (SCD-DP). Calibration was accomplished by using standards and gaseous streams of known concentration of sulfur compounds. The response factors agree with the calibration table of ASTM standard D 5504 (2008). The detection range for sulfur compounds is in μg m-3. The analytical procedure allowed the construction of a chromatographic chart of sulfur compounds present in several refinery gaseous effluents. SO2 was the most difficult compound to be determined because of its high reactivity.
  • Determination of 5-aminosalicylic acid in pharmaceutical formulations by square wave voltammetry at pencil graphite electrodes

    Uliana, Carolina V.; Yamanaka, Hideko; Garbellini, Gustavo S.; Salazar-Banda, Giancarlo R.

    Resumo em Inglês:

    An analytical method for the determination of the anti-inflammatory drug 5-aminosalicylic acid (5-ASA) in pharmaceutical formulations using square wave voltammetry at pencil graphite electrodes was developed. After the optimization of the experimental conditions, calibration curves were obtained in the linear concentration range from 9.78 × 10-7 to 7.25 × 10-5 mol L-1 resulting in a limit of detection of 2.12 ± 0.05 x 10-8 mol L-1. Statistical tests showed that the concentrations of 5-ASA in commercial tablets and enemas obtained with the proposed voltammetric method agreed with HPLC values at a 95% confidence level.
  • Development and validation of UV spectrophotometric method for determination of levofloxacin in pharmaceutical dosage forms

    Kassab, Nájla Mohamad; Amaral, Marcos Serrou do; Singh, Anil Kumar; Santoro, Maria Inês Rocha Miritello

    Resumo em Inglês:

    The objective of this research was to develop and validate an alternative analytical method for quantitative determination of levofloxacin in tablets and injection preparations. The calibration curves were linear over a concentration range from 3.0 to 8.0 μg mL-1. The relative standard deviation was below 1.0% for both formulations and average recovery was 101.42 ± 0.45% and 100.34 ± 0.85% for tablets and injection formulations, respectively. The limit of detection and limit of quantitation were 0.08 and 0.25 μg mL-1, respectively. It was concluded that the developed method is suitable for the quality control of levofloxacin in pharmaceuticals formulations.
  • Validação de método para determinação de resíduos de amoxicilina aplicado à validação de limpeza em indústria farmacêutica de penicilânicos Nota Técnica

    Gomes, Maria Luiza Pinheiro Costa; Souza, Scheilla Vitorino Carvalho de

    Resumo em Inglês:

    The aim of this work was the single-laboratory validation of a quantitative method for the determination of amoxicillin residues in support of cleaning control and validation. Linearity was demonstrated between 2.5 and 17.5 μg/mL, without matrix effects. Mean recoveries ranged from 84.00 to 103.74% and the relative standard deviation under repetitivity and within-reproducibility conditions were from 0.58 to 4.20% and from 0.79 to 4.39%, respectively. The theoretical limits of detection and quantification were 0.133 and 0.442 μg/mL, respectively. The studied method was suitable for cleaning control purpose within good manufacturing practices.
  • Determinação do teor de ésteres graxos em biodiesel metílico de soja por cromatografia gasosa utilizando oleato de etila como padrão interno Nota Técnica

    Marques, Marcelo Volpatto; Naciuk, Fabrício Fredo; Mello, Ana Maria de Souza; Seibel, Nair Maria; Fontoura, Luiz Antonio Mazzini

    Resumo em Inglês:

    A method for ester content determination in soybean methyl biodiesel was studied, using ethyl oleate as internal standard. A biodiesel sample was analyzed and had its purity estimated as 92.8%. Method accuracy was evaluated by comparison with the result obtained via EN14103, with a relative difference of 0.1%. Repetitivity and intermediate precision were estimated as 2 and 1.5%, respectively.
  • UV derivative spectrophotometric method for determination of estradiol valerate in tablets

    Mendez, Andreas S. L.; Deconto, Lislaine; Garcia, Cássia V.

    Resumo em Inglês:

    A derivative UV spectrophotometric method for determination of estradiol valerate in tablets was validated. The parameters specificity, linearity, precision, accuracy, limit of detection and limit of quantitation were studied according to validation guidelines. The first-order derivative spectra were obtained at N = 5, Δλ = 4.0 nm, and determinations were made at 270 nm. The method showed specificity and linearity in the concentration range of 0.20 to 0.40 mg mL-1. The intra and interday precision data demonstrated the method has good reproducibility. Accuracy was also evaluated and results were satisfactory. The proposed method was successfully applied to a pharmaceutical formulation.
  • Internal standard versus external standard calibration: an uncertainty case study of a liquid chromatography analysis

    Oliveira, Elcio Cruz de; Muller, Edson I.; Abad, Fernanda; Dallarosa, Juliana; Adriano, Cristine

    Resumo em Inglês:

    Traditionally, in the cigarettes industry, the determination of ammonium ion in the mainstream smoke is performed by ion chromatography. This work studies this determination and compares the results of this technique with the use of external and internal standard calibration. A reference cigarette sample presented measurement uncertainty of 2.0 μg/cigarette and 1.5 μg/cigarette, with external and internal standard, respectively. It is observed that the greatest source of uncertainty is the bias correction factor and that it is even more significant when using external standard, confirming thus the importance of internal standardization for this correction.
  • Em busca da conservação ambiental: a contribuição da percepção ambiental para a formação e atuação dos profissionais da Química Educação

    Freitas, Mirlaine R.; Macedo, Renato L. G.; Ferreira, Eric B.; Freitas, Matheus P.

    Resumo em Inglês:

    Planet transformations caused by human intervention in the last 200 years are largely due to chemical impact. Therefore, this study aimed to identify and analyze the environmental perception of undergraduate students and lecturers in the Chemistry course of the Federal University of Lavras, accounting for the topics "Environmental Definition" and "Relationship between Chemistry and Environment". Two thematic axes for discussion were proposed using theories of Social Representation and Environmental Complexity, with the aim of stimulating the conservationist reasoning and actions. Such axes were proposed to give support to the education of chemists at the undergraduate level.
  • El aprendizaje basado en problemas como estrategia para el cambio metodológico en los trabajos de laboratorio

    Llorens-Molina, Juan-Antonio

    Resumo em Inglês:

    The Problem Based Learning (PBL) can be used as a strategy for methodological change in conventional learning environments. In this paper, the integration of laboratory work in PBL grounded activities during an introductory organic chemistry course is described. The most decisive issues of their implementation are discussed. The results show how this methodology favours the laboratory work contextualization in subject-matter and promotes the Science-Technology-Society-Environment relationships. Besides, it contributes to competence development like planning and organization skills, information search and selection, cooperative work, etc., the same way as the tutorial action improvement.
  • Gestão das inovações incrementais, o caso Omeprazola Assuntos Gerais

    Lourenço, Alexandre Lopes; Lira, Luiz Marcelo; Carvalho, Denise Pires de; Melo, Paulo de Assis; Cláudio-da-Silva, Tereza Sollero

    Resumo em Inglês:

    Our report shows the strategies adopted by pharmaceutical industry in the development of incremental innovations, through the development carried out after the launch of omeprazole. Some improvements are really necessary and others are used only as a market strategy and evergreening.
  • Produção científica da área da Química no desenvolvimento da oceanografia no Brasil Assuntos Gerais

    Lacerda, Luiz Drude de; Marins, Rozane Valente

    Resumo em Inglês:

    This paper analyses the scientific contribution of chemists and of the Brazilian Chemical Society (SBQ) and its publications to the development of Oceanography in Brazil, as well as major drivers of this participation. A total of 528 articles were analyzed. Most articles (72%) originated in research groups not associated with graduate programs in oceanography. Nearly 50% dealt with the contamination of the marine environment, followed by chemical process studies (32%) and analytical methods development (15%). SBQ journals contributed with 78 articles (14.7% of the total), and rank 1st (QN) and 2nd (JBCS) among scientific journals publishing the analyzed articles.
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