Determinação eletroquímica da capacidade antioxidante de sucos de frutas industrializados usando o CRAC assay

Fruits juices are natural sources of several compounds that present antioxidant action. Together with the fruits, they contribute with almost 40% of the antioxidant capacity in a healthy diet avoiding and preventing diseases deriving from oxidative stress. The present study determined the antioxidant capacity of seven samples of industrialized fruits juices applying CRAC (Ceric Reducing/Antioxidant Capacity) assay, a new electrochemistry assay that evaluates, by means of chronoamperometric measurements, the ability of a sample in reducing species Ce4+ in acid media. At the end of the assay was obtained the following classification: cashew > guava > grape > mango > apple > orange > passion fruit.

Síntese, caracterização e análise térmica dos sais de lítio, sódio e potássio do ácido palmítico e do seu éster etílico

Alkaline salts of the palmitic acid were synthesized and characterized from aqueous and ethanolic medium. The salts were characterized by elemental analysis (EA) and infrared spectroscopy (IR). EA and IR, being its synthesis comproved, also characterized the ethyl palmitate. All the salts and the ester were submitted to thermal analysis using thermogravimetry (TG), and differential thermal analysis (DTA) in the temperature ranging from room to 700 ºC under air dynamic atmosphere. Differential scanning calorimetry (DSC) measurements were taken from -90 ºC up to temperatures close to the starting of the decomposition temperature, determined by thermogravimetry, using heating and cooling cycles.

Estudo da eletrocristalização de Ni e Ni-P sobre ultramicroeletrodo de platina

This work describes a comparative study of the electrocrystallization of Ni and Ni-P on Pt ultramicroelectrodes using chronoamperometric measurements. It was possible to confirm that in all cases a progressive nucleation was the predominant mechanism. Moreover, the application of the Atomistic Theory to the experimental rate of nuclei formation showed that the number of atoms in the critical nucleus was zero, except for Ni-P on Pt at low overpotentials were a value of one was observed. Furthermore, the physical characterisation of the different deposits on Pt by atomic force microscopy allowed observing the coalescence of the hemispherical nuclei of Ni and Ni-P at t max thus confirming the results obtained from the current-time analysis.

Dextranas em açúcares do estado de São Paulo

The characterization of dextran in sugars by size exclusion chromatography (SEC) has been carried out according to the number-average molecular weight (Mn), the weight-average molecular weight (Mw), the Z-average molecular weight (Mz), and the polydispersity (Mw/Mn). The results suggest that all the analyzed thirty sugar samples from São Paulo state were contaminated with two or three different dextran polymers. The collected data clearly point out that the total dextran content together with the mass distribution parameters Mw, Mn, Mz, and Mw/Mn should be considered during the evaluation of the quality of the sugar used for the cachaça sweeting process.

Aplicação do ultra-som em sistemas eletroquímicos: considerações teóricas e experimentais

The aim of this review is to present and discuss the applications of ultrasound in electrochemical systems such as in sonoelectroanalysis and sonoelectrolysis for the electrochemical combustion of organic compounds. Initially, theoretical and experimental aspects are discussed, particularly those related to the enhancement of mass transport and the surface cleaning effects. Some results are included to illustrate alternative geometries for the experimental measurements and the working electrodes used in these systems. In the sequence, the available publications are presented and discussed to demonstrate that ultrasound combined with electrochemical techniques is a powerful set-up for the detection of analytes such as metals and/or organic compounds in hostile media and for the effective destruction of toxic organic substances. At the end, a table summarizes the results already published in the literature.

Membranas biológicas homólogas preservadas em solução alcalina seguida de liofilização, glicerina a 98% e por liofilização para implantação em eqüinos

Objetivou-se, neste trabalho, avaliar as alterações físico-químicas proporcionadas pelo tratamento de centros tendinosos diafragmáticos homólogos em solução alcalina seguida de liofilização, para implantação na fáscia interna do músculo reto do abdome de eqüinos. As amostras foram tratadas em períodos de 24, 48, 72, 120 e 144 horas, liofilizadas e analisadas quanto à homogeneidade, flexibilidade e resistência à sutura das amostras. Posteriormente foram caracterizadas por calorimetria exploratória diferencial e microscopia eletrônica de varredura. Para a implantação nos eqüinos, foram utilizadas amostras tratadas por 72 horas seguidas de liofilização, amostras conservadas em glicerina 98% e amostras apenas liofilizadas, que foram retiradas após uma, nove e 18 semanas para avaliar a existência de aderências. Verificou-se que a homogeneidade e a flexibilidade são diretamente proporcionais ao aumento do tempo de tratamento em solução alcalina, enquanto que a resistência é inversamente proporcional ao aumento de tempo, sendo o tratamento por 72 horas intermediário para estas características. A calorimetria exploratória diferencial mostrou que o tratamento não desnatura o colágeno presente nas amostras. Na microscopia eletrônica de varredura, observou-se que o aumento de tempo de tratamento proporciona expansão de zonas menos densas do material. Em relação à formação de aderências, as amostras apenas liofilizadas apresentaram grau máximo na formação da classificação proposta, seguida pelas amostras conservadas em glicerina 98% com grau médio e as amostras tratadas em solução alcalina e liofilizadas, que foram classificadas em grau mínimo. Concluiu-se que o tratamento por 72 horas seria mais apropriado para implantação e que a integração tissular com a parede abdominal foi melhor em relação às amostras apenas liofilizadas e às conservadas em glicerina.

Potencialidades do uso de ultrassom na determinação do pesticida carbaril empregando eletrodos de diamante

The potentiality of the use of ultrasound radiation in association with a boron-doped diamond electrode was evaluated on the voltammetric determination of the pesticide carbaryl. Improvements in the sensitivity, limit of detection and reproducibility of the measurements were observed due to both, the enhancement of mass transport and the cleaning of the electrode surface provided by ultrasound. Satisfactory recovery levels for carbaryl in pure water (96-98%) and pineapple juice (89-92%) for quiescent and sonovoltammetric methodologies were obtained. These methodologies can be alternative tools for the analyses of pesticides in fruit samples, mainly the insonated condition that improve the analytical performance and dispense intermediary cleanings of the electrode surface.

A new consensus for Trypanosoma cruzi intraspecific nomenclature: second revision meeting recommends TcI to TcVI

In an effort to unify the nomenclature of Trypanosoma cruzi, the causative agent of Chagas disease, an updated system was agreed upon at the Second Satellite Meeting. A consensus was reached that T. cruzi strains should be referred to by six discrete typing units (T. cruzi I-VI). The goal of a unified nomenclature is to improve communication within the scientific community involved in T. cruzi research. The justification and implications will be presented in a subsequent detailed report.

Alameda Glette, 463, sede do Curso de Química da Universidade de São Paulo no período 1939-1965

As the foundation of the University of São Paulo completes 75 years, this article describes the history of a mansion at 463 Glette Boulevard, in São Paulo city, where several undergraduate courses of the University's Philosophy, Sciences and Letters Faculty operated until 1969. The first building of the school of Chemistry was erected there, 70 years ago. A brief retrospective of the Department of Chemistry at that place is given. The mansion was torn down by the middle of the 1970s, but it remained as a symbol of the school identity in the memory of all those who studied there.

Trypanocidal activity of Piper arboreum and Piper tuberculatum (Piperaceae)

In the scope of our ongoing research on bioactive agents from Brazilian flora, twenty-four extracts and fractions obtained from Piper arboreum Aub. and Piper tuberculatum Jacq. (Piperaceae) were screened for trypanocidal activity by using MTT colorimetric assay. The strongest activity was found in hexane fractions from the leaves of P. arboreum (IC50= 13.3 µg/ mL) and P. tuberculatum (IC50 = 17.2 µg/mL). Hexane fractions of the fruits of P. tuberculatum and P. arboreum showed potent toxic effects on epimastigote forms of Trypanosoma cruzi, with values of IC50 (µg/mL) of 32.2 and 31.3, respectively. Additionally, the phytochemical study of the hexane fraction of P. arboreum leaves furnished two pyrrolidine amides, piperyline (1) and 4,5-dihydropiperyline (2), which could be responsible, at least in part for the observed antiprotozoal activity.