Tereza S. Martins

Structural studies of mesoporous ZrO2-CeO2 and ZrO2-CeO2/SiO2 mixed oxides for catalytical applications

In this work the synthesis of ZrO2-CeO2 and ZrO2-CeO2/SiO2 were developed, based on the process to form ordered mesoporous materials such as SBA-15 silica. The triblock copolymer Pluronic P-123 was used as template, aiming to obtain crystalline single phase walls and larger specific surface area, for future applications in catalysis. SAXS and XRD results showed a relationship between ordered pores and the material crystallization. 90% of CeO2 leaded to single phase homogeneous ceria-zirconia solid solution of cubic fluorite structure (Fm3¯ m). The SiO2 addition improved structural and textural properties as well as the reduction behavior at lower temperatures, investigated by XANES measurements under H2 atmosphere.

Application of an Ionic Liquid in the Microwave Assisted Extraction of Cytotoxic Metabolites from Fruits of Schinus terebinthifolius Raddi (Anacardiaceae)

This work reports the application of an ionic liquid (1-butyl-3-methylimidazolium bromide, BMImBr) in the microwave assisted extraction (MAE) of metabolites from fruits of Schinus terebinthifolius. Dried fruits were individually extracted using BMImBr:H2O 1:1, v/v (experiment 1) and pure H2O (experiment 2) by MAE (10 min at 60 °C). After partition using EtOAc, the yield to experiment 1 was about 23% while to experiment 2 was 0.1%. The EtOAc fraction obtained from experiment 1 was purified by chromatographic methods to afford 3-oxotirucalla-7,24 Z-dien27-oic acid, 3a-hydroxytirucalla-7,24Z-dien-27-oic acid, 3a-acetoxytirucalla-7,24Z-dien-27-oic acid, gallic acid, and ethyl gallate, being the first occurrence of the third compound as natural product. Cytotoxic activity was evaluated in vitro against cancer cell lines (A2058, HeLa, SiHa, HCT, SKBR-3, U87, and B16F2Nex2), being 3a-acetoxytirucalla-7,24Z-dien-27-oic acid the more active metabolite with IC50 ranging from 10.9 ± 1.3 to 17.3 ± 1.4 µg mL -1 , lower than that determined to positive control cisplatin.

In situ X-ray absorption spectroscopy study of CuO–NiO/CeO2–ZrO2 oxides: redox characterization and its effect in catalytic performance for partial oxidation of methane

In this work we analyze the effect of adding CuO to a NiO/Ce0.9Zr0.1O2 oxide by in situ X-ray absorption near-edge structure XANES technique in Ce L3, Ni K and Cu K absorption edges in terms of sample reducibility and catalytic activity. The oxidation states of Ce, Ni and Cu cations are followed up during temperature programmed reduction (TPR) experiments in diluted hydrogen and during catalytic tests for partial oxidation of methane (POM) reaction. Redox behavior was correlated to conventional fixed bed reactor results. The effect of firing temperature, crystallite size, CeO2–ZrO2 support and the presence of Cu and/or Ni as an active phase is also analyzed. Results showed a beneficial effect of CuO addition in terms of Ce and Ni reduction. A stronger interaction of NiO species with the support was revealed upon analysis of XANES reduction profiles in sample NiO/ZDC in contrast to bimetallic CuO–NiO/ZDC sample. Reduction onset temperature was found to depend on Ni crystallite size, being markedly promoted when samples exhibited low values of crystallite size both in supported and non-supported CuO–NiO species. In situ catalytic experiments for partial oxidation of methane showed a clear interplay between the redox behavior from the Ce in the CeO2–ZrO2 support and the Ni from the active phase. Sample NiO/ZDC exhibited a continuous reduction of Ce cations in CH4 : O2 feed flow, carbon formation was detected in X-ray Powder Diffraction (XPD) patterns and Ni re-oxidation was found to take place, clear indications of catalyst deactivation. In contrast, sample CuO–NiO/Ce0.9Zr0.1O2 displayed a slight re-oxidation of Ce and no re-oxidation of Ni altogether with the suppression of carbon formation.

Improvement of cutaneous delivery of methylene blue by liquid crystals

ABSTRACT The purpose of this study was to evaluate the effect of composition and characteristics of liquid crystalline phases (LCPs) on cutaneous delivery of methylene blue (MB). LCPs were obtained by mixing Brij97® with water at various ratios; Brij97®:water at 8:2 (F8:2), 7:3 (F7:3), and 6:4 (F6:4) were selected, and MB was incorporated at 0.1%. F8:2 and F7:3 exhibited textures and small angle X‐ray scattering (SAXS) patterns corresponding to lamellar phase, whereas F6:4 displayed characteristics of hexagonal phase. All three LCPs were stable for 9months, and exhibited thixotropic pseudoplastic behaviour. Increasing water content increased viscosity. All three LCPs released less (3.2‐ to 6.6‐fold) MB than control gel (3.0% hydroxyethylcellulose (HEC)+0.1% MB), demonstrating their ability to sustain release. Despite the lower release, all LCPs improved skin retention of MB at 6h post‐application (1.3‐ to 2.1‐fold) compared to the control gel. Among the LCPs, F8:2‐mediated skin retention of MB was more pronounced, followed by F7:3. Consistent with the increased penetration, transepidermal water loss (TEWL) also increased after treatment with the LCPs (2.0–2.8 fold), which suggests their influence on skin barrier. Irritation studies by Hens Egg Test – Chorioallantoic Membrane (HET‐CAM) suggest that F7:3 and F6:4 may be better tolerated by the skin than F8:2.

Encapsulation of diptheria anatoxin into ordered mesoporous silica

Marcia Carvalho De Abreu Fantini1, Tereza S. Martins2, Cristiano L. P. Oliveira1, Marcela A. Bordenalli3, Milene T. Franco3, Osvaldo A. Sant ́Anna3, Martin K. Rasmussen4, Heloisa N. Bordallo4 1Physics Institute-University Of Sao Paulo, Sao Paulo, Brazil, 2Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, São Paulo, Brazil, 3Instituto Butantan, São Paulo, Brazil, 4Niels Bohr Institute, Copenhagen University, Copenhagen, Denmark E-mail: mfantini@if.usp.br

XANES studies of zirconia-ceria/Ni during partial/total methane oxidation

1 Universidade de São Paulo, Departamento de Física Aplicada, São Paulo, Brazil, 2 Universidade Federal de São Paulo, Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Diadema, Brasil, 3 Centro de Investigaciones en Sólidos, CINSO-UNIDEF-CONICET, Buenos Aires, Argentina, 4 Universidad Nacional del Comahue, Laboratório de Caracterización de Materiales, Facultad de Ingeniería, Neuquén, Argentina

Addressing key ecological questions to support policy-making in Brazil

In Brazil, there is generally a lack of information flow between scientists and policy makers. Here, we address 29 ecological questions of high policy relevance in Brazil, in an attempt to encourage the participation of science in decision-making. Similar addresses have been made by British and American scientists (Fleishman et al., 2011; Sutherland et al., 2006), and it is our goal to bring such matters to the Brazilian reality. We had several meetings during an Ecosystem Ecology seminar held at the Federal University of Juiz de Fora and categorised our questions into five different topics. Brief introductory paragraphs are shown below each topic and the questions are presented subsequently without any order of relevance.