Ciclização do lapachol induzida por sais de tálio III

This work describes the cyclization of lapachol (1) induced by thallium triacetate (TTA) and thallium trinitrate (TTN) in several solvents using magnetic stirring and under microwave irradiation. alpha-Xyloidone (2) - dehydro-alpha-lapachone - was obtained as the main product in these reactions in 20 75% yield. However, rhinacanthin-A (4) was isolated as main product in a 40% yield, using TTA and acetic anhydride:water (1:1) as solvent, and dehydro-iso-alpha-lapachone (3) in 21% yield, using TTA and dichloromethane as solvent. The reaction time decreased drastically under microwave conditions, but the yields of these reactions were not the expected.

A influência dos ácidos hexenurônicos no rendimento e na branqueabilidade da polpa kraft

This study investigated the impact of pulp hexenuronic acids (HexAs) content on pulping yield by changing cooking reaction temperature. The bleachability of pulps containing variable amounts of HexAs was also investigated. The cooking at 170 ºC produced pulp of kappa number, HexAs and screen yield of 16.2, 49.4 mmol/kg and 50.2%, respectively, whereas the cooking at 156 ºC resulted pulp of kappa 17.0, 61.3 mmol/kg HexAs and 50.8% screened yield. The pulp produced at lower cooking temperature also showed better bleachability as evaluated by the total amount of active chlorine required to achieve 90% ISO. The sequence OA HT D(EP)DD showed the lowest bleaching performance among all.

Estudo químico e biológico de Tephrosia toxicaria Pers.

The ethanol extracts from leaves, stems, pods and roots were assayed against the 3rd instar Aedes aegypti larvae and the highest activity was observed in the roots extracts (LC50 47.86 ppm). This extract was submitted to partition with hexane, chloroform, ethyl acetate and methanol. The respective fractions were bioassayed and the best larvicidal activities were identified in the hexane (LC50 23.99 ppm) and chloroform (LC50 13.80 ppm) fractions. Antioxidant activity (DDPH method) was observed in the ethanol extract (IC50 276 µg/mL) from roots of T. toxicaria. Fractions from this extract were also tested and the highest antioxidant activity (IC50 89 µg/mL) was found in the methanol fraction. The flavonoids iso-obovatin (1), obovatin (2), 6a,12a-dehydro-β-toxicarol (3), 6a,12a-dehydro-α-toxicarol (4) and α-toxicarol (5) were isolated and bioassayed against A. aegypti. The flavonoid 5 showed the best larvicidal activity (LC50 24.55 ppm). The antioxidant activity of 2 was investigated and showed IC50 3.370 µg/mL. The antioxidant and larvicidal activities of Tephrosia toxicaria are reported for the first time.

Branqueamento de polpa celulósica kraft de eucalipto com peróxido ácido ativado por molibdênio

Optimum conditions to run the P Mo stage for bleaching eucalyptus kraft pulp were 90 ºC, pH 3.5, 2 h, 0.1 kg/t Mo and 5 kg/t H2O2. The P Mo stage efficiency increased with decreasing pH (1.5-5.5) and increasing temperature (75-90 ºC), time (2-4 h), and hydrogen peroxide (3-10 kg/t) and molybdenum concentration (0.1-0.4 kg/t). The implementation of the P Mo stage, as replacement for the A stage, decreased total active chlorine demand of the OAZDP sequence by 6 kg/t to reach 90% ISO, both in laboratory and mill scale. Such practice resulted in decreased bleaching chemical costs to produce fully bleached pulp of 90% ISO.

Alcaloides iboga de Peschiera affinis (Apocynaceae) - Atribuição inequívoca dos deslocamentos químicos dos átomos de hidrogênio e carbono: atividade antioxidante

Six known alkaloids iboga type and the triterpen α- and β-amyrin acetate were isolated from the roots and stems of Peschiera affinis. Their structures were characterized on the basis of spectral data mainly NMR and mass spectra. 1D and 2D NMR spectra were also used to unequivocal ¹H and 13C chemical shift assignments of alkaloids. The ethanolic extract of roots, alkaloidic and no-alkaloidic fractions and iso-voacristine hydroxyindolenine and voacangine were evaluated for their antioxidative properties using an autographic assay based on β-carotene bleaching on TLC plates, and also spectrophotometric detection by reduction of the stable DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical.

Determinacion de la bioactividad y la resistencia a la compresion de bloques de Poliapatita

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.

Alvejamento químico de caulins Brasileiros: efeito do potencial eletroquímico da polpa e do ajuste do pH

Samples of Kaolin from different regions in Brazil were characterized by XRD, SEM and chemical analysis. A chemical bleaching study with pH adjustment was accomplished with the fractions below 37 μm, after classification by screening. The main objective was to evaluate the conditions of chemical bleaching that most increase the brightness of these kaolin's samples. Increases between 2.63 and 2.98% in the brightness (ISO) were observed after the chemical bleaching. We could say that the reduction of Fe3+ to Fe2+ during the chemical bleaching promoted an increase in the brightness, based on the Pourbaix Diagrams.

Estimativa da incerteza de medição: estudo de caso no ensaio de migração de ε-caprolactama com determinação por CG-DIC

The estimation of measurement uncertainty of an analytical result is an important tool to be applied for compliance to ISO IEC 17025. Through the available guides it is possible to establish procedures and criteria for the estimation of measurement uncertainty. This paper presents a case study on the estimation of measurement uncertainty in migration the test of ε-caprolactam from the polyamide 6 packages to fatty foods with determination by GC-FID. The calculation methodology used for the estimation of measurement uncertainty for the migration test was developed based on the guides EURACHEM / CITAC and ISO GUM, taking into account relevant aspects of the migration test. The expanded uncertainty estimated was approximately 23% of the concentration of migration.

Síntesis química, estudios de caracterización y reactividad de un material catalítico a base de ZrO2-H3PW12O40

In this work, the preparation and characterization of materials such as zirconium oxide (ZrO2) and phosphotungstic acid promoted zirconium oxide (ZrO2-H3PW12O40) is presented. Physico-chemical characterization results showed that addition of H3PW12O40 acted as both a textural and chemical promoter of zirconium oxide. The incorporation of phosphotungstic acid into the ZrO2 matrix delayed the sintering of the material and stabilized ZrO2 in the tetragonal phase. ZrO2 acidity was also enhanced, developing strong acid sites on its surface. The Pt/ZrO2-H3PW12O40 catalyst was active for n-pentane isomerization at 250 °C, exhibiting high selectivity to iso-pentane (95%). This result is probably due to its suitable acidity.

INFLUÊNCIA DO CONTEÚDO DE XILANAS NA BRANQUEABILIDADE, PROPRIEDADES HIGROSCÓPICAS, FISICO-MECÂNICAS E ÓPTICA DE POLPAS BRANQUEADAS DE EUCALIPTO

Bleached eucalypt kraft pulps are widely used in print and writing (P&W) and tissue paper manufacture. Among the quality requirements of pulp for these papers, xylan content has been controversial. The objective of this study was to evaluate the influence of xylan content on bleachability, hygroscopic, physic-mechanical and optical properties of the pulp. In this study industrial unbleached eucalyptus kraft pulp (15.6% xylans) treated with different NaOH loads to change its xylan content was used. Subsequently, pulps were bleached by the ODHT(EP)D sequence to achieve 90% ISO of brightness, then refined and submitted to hygroscopic, physicomechanical and optical tests. NaOH treatments decreased the xylan content to 14.5-5.9% using NaOH loads of 10-70 g L-1. Pulp bleachability was not significantly affected by xylan content decrease. The decrease in xylan content negatively affected the water retention value and Klemm capillarity of the pulp, while water absorption capacity was positively affected. Tensile and tear index were negatively influenced by the reduction in xylan content, whereas bulk and light scattering coefficient increased.

Caracterização fisiomorfológica de isolados de Colletotrichum musae

Isolados de Colletotrichum musae obtidos de quatro cultivares de banana (Musa spp.) 'Comprida', 'Maçã', 'Pacovan' e 'Prata' foram estudados quanto ao aspecto morfológico dos conídios, apressórios, características culturais, diâmetro das colônias em meio BDA, germinação dos conídios em água destilada esterilizada e meio líquido BD, como também, quanto ao efeito da combinação de C/N no crescimento micelial, esporulação e peso da matéria seca, sob alternância luminosa, a aproximadamente, 25 ºC. No estudo da relação C/N, as fontes de carbono foram dextrose, sacarose e sorbitol e as de nitrogênio asparagina, peptona e nitrato de potássio combinadas na proporção 10:1 (10 g de carbono para 1 g de nitrogênio). Os resultados mostraram conídios hialinos, com forma e tamanhos característicos da espécie, variando dentro dos limites estabelecidos para a espécie. A relação comprimento/largura foi menor para os isolados Iso-1, Iso-6 e Iso-8 oriundos de banana 'Comprida'. A germinação de conídios ocorreu a partir de 8 h de incubação, havendo diferença significativa entre os isolados, quanto ao percentual de conídios germinados. Foram observados apressórios em todos os isolados, variando em quantidade. Houve diversidade nas características culturais e diâmetro das colônias dos isolados, em BDA. Com relação às combinações C/N, a análise estatística revelou diferença significativa entre os isolados, sob efeito da interação C/N, bem como dos fatores independentes, sobre o crescimento micelial, produção de esporos e peso seco do micélio. De um modo geral, as combinações de carbono com peptona favoreceram esses três processos fisiológicos, porém com diferença significativa entre os isolados de C. musae dentro de cada processo considerado.

Indução de resistência a Fusarium oxysporum f. sp. Tracheiphilum em Caupi: eficiência de indutores abióticos e atividade enzimática elicitada

Foram avaliados os efeitos de indutores abióticos em cultivares de caupi inoculadas com Fusarium oxysporum f. sp. tracheiphilum quanto à severidade, controle da doença e atividade enzimática. Para isso, plantas das cultivares IPA-206 e BR-17 Gurguéia com cinco dias de idade foram pulverizadas com soluções aquosas de ASM (5,0 g do i.a./100 L de água), BABA (1,5 mM) e quitosana (2,0 mg/mL), no primeiro par de folhas e inoculadas, após sete dias da germinação, com 20 mL de uma suspensão de 1 x 10(6) conídios/mL do isolado ISO-PE. A avaliação da severidade da doença foi realizada aos 25 dias após a germinação, através de escala de notas e índice de doença. As atividades das enzimas beta-1,3-glucanase, peroxidase e fenilalanina amônia liase (PAL) foram determinadas em plantas submetidas aos tratamentos anteriores, coletadas aos cinco e 10 dias após a inoculação. Foi observada diferença significativa entre os indutores e a testemunha, nas duas cultivares testadas, aos cinco e 10 dias, destacando-se o indutor ASM, proporcionando um controle da doença de 68,90% e 71,59% nas cultivares BR-17 Gurguéia e IPA-206, respectivamente. O indutor ASM apresentou melhores resultados nas atividades de beta-1,3-glucanase, peroxidase e PAL, destacando-se na cultivar IPA-206 nos dois períodos analisados. Os indutores BABA e quitosana diferiram da testemunha, na atividade de PAL e beta-1,3-glucanase, nessa mesma cultivar, aos cinco dias após a inoculação.

Catálise estereoespecífica de estireno por titanocenos alquil-substituídos do tipo (RCp)2TiCl2

Uma série de sete complexos alquil substituídos do tipo (RCp)2TiCl2 (R= H, etila, n-propila, iso-propila, n-butila, iso-amila, ciclo-hexila) foi preparada juntamente com o ainda inédito contendo R= sec-butila, e o efeito do substituinte na polimerização do estireno foi investigada à temperaturas de polimerização de 0 e 50 ºC. Foi encontrado que R = n-butila maximiza a produção de poliestireno sindiotático. Ligantes alquilas com R = RCH2- são superiores aos R = RR’CH- e ao precursor Cp2TiCl2 na produção de poliestireno sindiotático de alto peso molecular.

Gestão da qualidade total: introdução dos conceitos e a sua utilização em um curso para abordar o comportamento individual do aluno/profissional/cidadão

A introdução do assunto qualidade, segundo as necessidades de mercado abre espaço para a discussão da qualidade como necessidade pessoal, e também para a formação do cidadão/profissional, além de introduzir assuntos específicos de administração de empresas. Dessa forma, foi oferecida uma disciplina optativa para os alunos do Instituto de Química do Campus de Araraquara, abordando o tema Qualidade e foi denominada "Gestão da Qualidade" por três anos seguidos. Da avaliação geral do curso extraiu-se que ele deveria ser realizado sempre, que o tema é atual e relevante e contribui para a formação profissional/pessoal. Com relação ao comprometimento com o curso de graduação, cerca de metade dos alunos assume o seu comprometimento com os estudos e os restantes dizem estarem somente envolvidos. Conclui-se, portanto que o curso atingiu os seus objetivos propostos, introduziu os principais conceitos de qualidade segundo as normas da qualidade da série ISO 9000 e suscitou a discussão da formação do aluno/profissional/cidadão.

Differentiation of Colletotrichum gloeosporioides isolates by using total proteins and esterase electrophoretic patterns and extracellular enzymes production

Isolates of Colletotrichum gloeosporioides (ISO-1, ISO-2, ISO-3, ISO-4, ISO-5 and ISO-6), the causal agent of anthracnose disease on mango fruits, were characterized by electrophoretic patterns of total proteins and esterase in polyacrylamida gel, and also, by production of extracellular enzymes on specific solid substrate. The electrophoretic analysis showed variation in number, intensity of coloration and position of the bands in the gel at each studied system tested. In contrast to the monomorphic behavior to total proteins, high esterase polymorfism was observed indicating difference among isolates. All isolates showed the activity of extracellular enzymes such as amylase, lipase, and protease with some variation among them. The proteolitic activity seemed to be more accentuated than the two other enzymes studied.