Santos E.B.,Federal University of São Paulo |
Ferlin S.,Institute Quimica |
Fostier A.H.,Institute Quimica |
Mazali I.O.,University of Campinas
Journal of the Brazilian Chemical Society | Year: 2017
This study reports a functional passive sampler for monitoring gaseous elemental mercury (GEM). The material consists of gold nanoparticles (AuNP) deposited forming a film on thiol-modified glass slides. AuNP colloid was synthesized using sodium citrate, resulting in a size of 24.2 ± 0.8 nm, as determined by transmission electron microscopy analysis. For the indoor test, AuNP films were placed into Petri plates. One part of the lot was kept exposed to the laboratory's atmosphere and the other part was stored in closed plate (control). The films were removed from both plates along a month and analyzed using a direct mercury analyzer. A linear relationship between Hg retention and exposure time was obtained until the 23rd day, which allowed to calculate a GEM retention rate of 2.2 ng g-1 day--1; the maximum retention capacity was around 50 ng g-1. This study provides an efficient method for indoor monitoring of GEM using AuNP films as passive sampler.
Martinez-Vazquez M.,Institute Quimica
Biochemical Systematics and Ecology | Year: 2014
A chemical analysis of Ibervillea lindheimeri (A. Gray) Greene led to the isolation of 23,24-dihydrocucurbitacin F (1), 23,24-dihydrocucurbitacin D (2) and 2-O-β-D-glucopyranosyl 23,24-dihydrocucurbitacin D (3). Their structures were identified by spectroscopic analyses and by comparison of their spectral data with those reported in the literature. In addition, 10 compounds were detected by GC-MS analyses from the hexane extract. To the best of our knowledge, this is the first report examining the chemical composition of I. lindheimeri. © 2014 Elsevier Ltd.
Macias-Rubalcava M.L.,Institute Quimica |
Ruiz-Velasco Sobrino M.E.,Institute Quimica |
Melendez-Gonzalez C.,Institute Quimica |
King-Diaz B.,University of the Basque Country |
Lotina-Hennsen B.,University of the Basque Country
Journal of Photochemistry and Photobiology B: Biology | Year: 2014
In a search for natural herbicides, we investigated the action mechanism of the naphthoquinone spiroketals, isolated from the endophytic fungus Edenia gomezpompae: preussomerins EG1 (1) and EG4 (2), and palmarumycins CP17 (3), and CP2 (4) on the photosynthesis light reactions. The naphthoquinone spiroketals 1-4 inhibited the ATP synthesis in freshly lysed spinach thylakoids from water to MV, and they also inhibited the non-cyclic electron transport in the basal, phosphorylating and uncoupled conditions from water to MV. Therefore, they act as Hill reaction inhibitors. The results suggested that naphthoquinone spiroketals 1-4 have two interactions and inhibition site on the PSII electron transport chain. The first one involves the water splitting enzyme inhibition; and, the second on the acceptor site of PSII in a similar way that herbicide Diuron, studied by polaroghaphy and corroborated by fluorescence of the chlorophyll a of PSII. The culture medium and mycelium organic extracts from four morphological variants of E. gomezpompae were phytotoxic, and the culture medium extracts were more potent than mycelium extracts. They also act as Hill reaction inhibitors. © 2014 Elsevier B.V. All rights reserved.
Torres-Palma R.A.,Institute Quimica |
Torres-Palma R.A.,University of Savoy |
Torres-Palma R.A.,Ecole Polytechnique Federale de Lausanne |
Nieto J.I.,Ecole Polytechnique Federale de Lausanne |
And 3 more authors.
Water Research | Year: 2010
This paper explores the degradation of a model pollutant, bisphenol A, by an advanced oxidation process that combines sonolysis, Fe2+, and TiO2 in a photoassisted process. Experiments were done under saturated oxygen conditions. The effect of different Fe2+ (0.56 and 5.6 mg/L) and TiO2 (10 and 50 mg/L) concentrations was investigated on both the elimination and mineralization of the pollutant. A pronounced synergistic effect that led to the complete and rapid elimination of dissolved organic carbon (DOC) was observed even at low catalyst loadings. In this system, almost a complete removal of DOC (93%) was observed after 4 h using 10 and 5.6 mg/L of TiO2 and Fe2+, respectively, whereas at the same time, only 5, 6, and 22% of DOC was removed by an individual process alone (TiO2 photocatalysis, ultrasound, and photo-Fenton, respectively). In this system, ultrasound has the principal role of eliminating the initial substrate and providing hydrogen peroxide for the photocatalytic systems, while photo-Fenton and TiO2 photocatalysis are mainly responsible for the transformation of the intermediates in CO2 and H2O. The role of H2O2 generated from the sonochemical process is also discussed. © 2010 Elsevier Ltd. All rights reserved.
Maldonado E.,Institute Quimica |
Perez-Castorena A.L.,Institute Quimica |
Garces C.,Institute Quimica |
Martinez M.,Autonomous University of Queretaro
Steroids | Year: 2011
Two new withanolides, philadelphicalactone C (1) and philadelphicalactone D (4), along with the known withaphysacarpin (3), ixocarpanolide (5), philadelphicalactone A (6), and ixocarpalactone A (7) were isolated from the aerial parts of Physalis philadelphica Lam. Structures of these compounds were determined by spectroscopic analyses and that of philadelphicalactone C (1) was confirmed by X-ray crystallographic analysis. Evaluation of the cytotoxic activity of all isolates and the derivative 2 against a panel of human cancer cell lines indicated a potent activity of compounds 2, 3, 6, and 7. © 2011 Elsevier Inc. All rights reserved.
Minutolo P.,CNR Institute for Research on Combustion |
Commodo M.,CNR Institute for Research on Combustion |
Santamaria A.,CNR Institute for Research on Combustion |
Santamaria A.,Institute Quimica |
And 2 more authors.
Carbon | Year: 2014
Two-dimensional carbon nanostructures have been produced via flame synthesis. Flame conditions and sampling methods have been optimized for the collection of the carbon nanostructures and for their characterization. Atomic Force Microscopy, Differential Mobility Analysis and Raman spectroscopy have been used to characterize the morphology and the chemical composition of these carbon nanostructures. Results show that a network of aromatic compounds connected by non-aromatic bonding arrange to form bi-dimensional structures that assume an atomically thin disk-like shape when deposited on a substrate. The in plane lateral dimension is of the order of tens of nanometers, and the height of about 3 Å. In spite of a significant amount of disorder, Raman spectroscopy evidences that lattice distortion is not very large in these flame nano-disks. © 2013 Elsevier Ltd. All rights reserved.
PubMed | RWTH Aachen, Institute Quimica and Autonomous University of Mexico State
Type: | Journal: Chemistry (Weinheim an der Bergstrasse, Germany) | Year: 2017
Experimental charge density studies of hexachloro-cyclo-triphosphazene (1) and the boat conformation of octachloro-cyclo-tetraphosphazene (2a) were performed in order to unambiguously describe the origin of the electron delocalization in the P3N3 ring in 1. The obtained results were compared to DFT studies in solid state and the gas phase. Electron density analysis revealed a highly polarized nature of the P-N bonds and a modular structure of the P3N3 and P4N4 rings, which can be separated into independent Cl2PN units with a perfect transferability between the compounds. Further analysis of the source function experimentally proves the presence of negative hyperconjugation involving both out-of-plane and in-plane nitrogen electrons as well as electrons of the chlorine atoms. Finally, these results discard the presence of pseudoaromatic delocalization in the nearly-planar P3N3 ring.
Puertas-Mejia M.A.,Institute Quimica |
Puertas-Mejia M.A.,CSIC - Center for Environmental Sciences |
Ruiz-Diez B.,CSIC - Center for Environmental Sciences |
Fernandez-Pascual M.,CSIC - Center for Environmental Sciences
Biochemical Systematics and Ecology | Year: 2010
Zea mays (maize) and Hordeum vulgare (barley) plants were analyzed in order to study the variation in response to Cadmium (Cd) toxicity based on development of leaf symptoms, effect in dry matter production, Cd uptake, lipid peroxidation and effect on cell ultrastructure in leaves and roots. Cd accumulation in roots of Z. mays and H. vulgare was 18-50 times higher than in the aerial parts. Malondialdehyde (MDA) content was more affected in the roots of both Z. mays and H. vulgare than in shoots (60 and 56-51 and 40%, respectively). At ultrastructural level, in Cd treated seedlings, a decline in the vacuolar content of barley roots cells and maize leaf cells was observed. Results corroborate that these gramineous crops can uptake and accumulate substantial amounts of Cd especially in roots. Therefore, H. vulgare and Z. mays could have a phytostabilization potential and thereafter could be tested in phytoremediation technologies. © 2010 Elsevier Ltd. All rights reserved.
Valencia D.,University of Sonora |
Alday E.,University of Sonora |
Robles-Zepeda R.,University of Sonora |
Garibay-Escobar A.,University of Sonora |
And 6 more authors.
Food Chemistry | Year: 2012
Propolis is widely used as a folk medicine and as a constituent of health foods in many parts of the world. The main purpose of this study was to evaluate the seasonal effect on the chemical composition and biological activities (antiproliferative and antioxidant activities) of Sonoran propolis (Mexico). Propolis was collected during all four seasons of the year and chemical composition, antiproliferative, and free-radical scavenging activities of collected propolis were evaluated by HPLC, MTT, and DPPH assays, respectively. The relative abundance of the main chemical constituents of propolis was similar in all propolis samples analysed. In contrast, significant differences were observed in their antiproliferative activity in the B-cell lymphoma cancer cell line M12.C3.F6. Propolis collected in the spring showed the highest inhibitory effect on the growth of cancer cells. All propolis samples had weak free-radical scavenging activity. Our results indicate that season had a significant effect on the antiproliferative properties of Sonoran propolis. © 2011 Elsevier Ltd. All rights reserved.
Liu Y.,Imperial College London |
Childs R.A.,Imperial College London |
Palma A.S.,Imperial College London |
Palma A.S.,New University of Lisbon |
And 5 more authors.
Methods in Molecular Biology | Year: 2012
Carbohydrate microarrays, since their advent in 2002, are revolutionizing studies of the molecular basis of protein-carbohydrate interactions both in endogenous recognition systems and pathogen-host interactions. We have developed a unique carbohydrate microarray system based on the neoglycolipid (NGL) technology, a well-validated microscale approach for generating lipid-tagged oligosaccharide probes for use in carbohydrate recognition studies. This chapter provides an overview of the principles and key features of the NGL-based oligosaccharide microarrays, and describes in detail the basic techniques - from the preparation of NGL probes to the generation of microarrays using robotic arraying hardware, as well as a general protocol for probing the microarrays with carbohydrate-binding proteins. © 2012 Springer Science+Business Media, LLC.