Filamentous fungi from the Atlantic marine sponge Dragmacidon reticulatum

Dragmacidon reticulatum is a marine sponge of wide occurrence in the Eastern and Western Atlantic. Little is known about D. reticulatum fungal diversity. Filamentous fungi recovered from D. reticulatum were assessed in the present study using a polyphasic taxonomic approach, including classical morphology, molecular biology and MALDI-TOF ICMS. Ninety-eight fungal strains were isolated from two D. reticulatum samples by using six different culture media, which were identified up to the genus level. Sixty-four distinct fungal ribotypes were obtained, distributed among twenty-four different genera belonging to the Ascomycota and Zygomycota. Representatives of Penicillium and Trichoderma were the most diverse and abundant fungi isolated. Amongst Penicillium spp. three isolates belonged to the same ribotype can be considered as a putative new species. Data derived from the present study highlight the importance of using a polyphasic approach to get an accurate identification in order to structure a reliable culture collection. © 2012 Springer-Verlag Berlin Heidelberg.

Adsorption of heavy metal ions and epoxidation catalysis using a new polyhedral oligomeric silsesquioxane

The objective of this research was the preparation of a silsesquioxane functionalized with eight chloropropyl chains (T8-PrCl) and of a new derivative functionalized with a pendant linear chain (2-amino-1,3,4-thiadiazole - ATD; T8-Pr-ATD). The two nanostructured materials were characterized by 13C and 29Si NMR, FTIR and elemental analysis. The new nanostructured material, octakis[3-(2-amino-1,3,4-thiadiazole)propyl] octasilsesquioxane (T8-Pr-ATD), was tested as a ligand for transition-metal ions with a special attention to adsorption isotherms. The adsorption was performed using a batchwise process and the organofunctionalized surface showed the ability to adsorb the metal ions Cu (II), Co (II), and Ni (II) from water and ethanol. The adsorption isotherms were fitted by Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) model. The kinetics of adsorption of metals were performed using three models such as pseudo-first order, pseudo-second order and Elovich. The Langmuir and Elovich models were the most appropriate to describe the adsorption and kinetic data, respectively. Furthermore, the T8-Pr-ATD was successfully applied to the analysis of environmental samples (river and sea water). Subsequently, a new nanomaterial was prepared by functionalization of the T8-Pr-ATD with a Mo (II) organometallic complex (T8-Pr-ATD-Mo). Only a few works in the literature have reported this type of substitution, and none dealt with ATD and Mo (II) complexes. The new Mo-silsesquioxane organometallic nanomaterial was tested as precursor in the epoxidation of cyclooctene and styrene. © 2012 Elsevier B.V.

The role of hierarchical morphologies in the superior gas sensing performance of CuO-based chemiresistors

The development of gas sensors with innovative designs and advanced functional materials has attracted considerable scientific interest given their potential for addressing important technological challenges. This work presents new insight towards the development of high-performance p-type semiconductor gas sensors. Gas sensor test devices, based on copper (II) oxide (CuO) with innovative and unique designs (urchin-like, fiber-like, and nanorods), are prepared by a microwave-assisted synthesis method. The crystalline composition, surface area, porosity, and morphological characteristics are studied by X-ray powder diffraction, nitrogen adsorption isotherms, field-emission scanning electron microscopy and high-resolution transmission electron microscopy. Gas sensor measurements, performed simultaneously on multiple samples, show that morphology can have a substantial influence on gas sensor performance. An assembly of urchin-like structures is found to be most effective for hydrogen detection in the range of parts-per-million at 200 °C with 300-fold larger response than the previously best reported values for semiconducting CuO hydrogen gas sensors. These results show that morphology plays an important role in the gas sensing performance of CuO and can be effectively applied in the further development of gas sensors based on p-type semiconductors. High-performance gas sensors based on CuO hierarchical morphologies with in situ gas sensor comparison are reported. Urchin-like morphologies with high hydrogen sensitivity and selectivity that show chemical and thermal stability and low temperature operation are analyzed. The role of morphological influences in p-type gas sensor materials is discussed. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Adsorption and release of micronutrients by humin extracted from peat samples

The objective of this work was to investigate the adsorption of micronutrients in humin and to verify the ability to release these elements in water. The first step was to determine the adsorption capacity of humin for several essential plant micronutrients and check the kinetic parameters. The order of adsorption was Zn < Ni < Co < Mn < Mo < Cu < Fe, whereas Zn showed maximum values of ca. 2.5 mg g-1 and Fe values of ca. 0.5 mg g-1 for systems containing 1 g of humin. Iron presented higher percentages of release (ca. 100%) and Co the lowest percentages (0.14%). The findings suggested that the use of humin enriched with micronutrients can be a promising alternative for the fertilization of agricultural soils, with the additional benefit of incorporating organic matter present in the form of humic substances into the soil and improving the agricultural productivity. © 2013 Sociedade Brasileira de Química.

Optimal single-embryo mass spectrometry fingerprinting

In pre-implantation embryos, lipids play key roles in determining viability, cryopreservation and implantation properties, but often their analysis is analytically challenging because of the few picograms of analytes present in each of them. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) allows obtaining individual phospholipid profiles of these microscopic organisms. This technique is sensitive enough to enable analysis of individual intact embryos and monitoring the changes in membrane lipid composition in the early stages of development serving as screening method for studies of biology and biotechnologies of reproduction. This article introduces an improved, more comprehensive MALDI-MS lipid fingerprinting approach that considerably increases the lipid information obtained from a single embryo. Using bovine embryos as a biological model, we have also tested optimal sample storage and handling conditions before the MALDI-MS analysis. Improved information at the molecular level is provided by the use of a binary matrix that enables phosphatidylcholines, sphingomyelins, phosphatidylserines, phosphatidylinositols and phosphoethanolamines to be detected via MALDI(±)-MS in both the positive and negative ion modes. An optimal MALDI-MS protocol for lipidomic monitoring of a single intact embryo is therefore reported with potential applications in human and animal reproduction, cell development and stem cell research. Copyright © 2013 John Wiley & Sons, Ltd. Copyright © 2013 John Wiley & Sons, Ltd.

Synthesis and characterization of 3-[(thiourea)-propyl]-functionalized silica gel and its application in adsorption and catalysis

The objective of this research was the preparation of a silica gel functionalized successively with 3-chloropropyltrimethoxysilane (SG-PrCl) and thiourea (SG-Pr-THIO), and its application in adsorption and catalysis. The materials were characterized by 13C and 29Si NMR, FTIR, scanning electron micrographs (SEM), analysis of nitrogen and elemental analysis. Aiming at its application in adsorption, the [3-(thiourea)-propyl] silica gel (SG-Pr-THIO) was tested as an adsorbent for transition-metal ions using a batchwise process. The organofunctionalized surface showed the ability to adsorb the metal ions Cd(ii), Cu(ii), Ni(ii), Pb(ii) and Co(ii) from water, ethanol and acetone. The adsorption isotherms were fitted by Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) models. The kinetics of adsorption of metals were performed using three models such as pseudo-first order, pseudo-second order and Elovich. The Langmuir and pseudo-first order models were the most appropriate to describe the adsorption and kinetic data, respectively. With the purpose of application in catalysis, the SG-Pr-THIO was reacted with a Mo(ii) organometallic complex, forming the new material SG-Pr-THIO-Mo. Only a few works in the literature have reported this type of reaction, and none dealt with thiourea and Mo(ii) complexes. The new Mo-silica gel organometallic material was tested as catalyst in the epoxidation of cyclooctene and styrene. © 2013 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.

Nanocomposite PAAm/methyl cellulose/montmorillonite hydrogel: Evidence of synergistic effects for the slow release of fertilizers

In this work, we synthesized a novel series of hydrogels composed of polyacrylamide (PAAm), methylcellulose (MC), and calcic montmorillonite (MMt) appropriate for the controlled release of fertilizers, where the components presented a synergistic effect, giving very high fertilizer loading in their structure. The synthesized hydrogel was characterized in relation to morphological, hydrophilic, spectroscopic, structural, thermal, and kinetic properties. After those characterizations, the application potential was verified through sorption and desorption studies of a nitrogenated fertilizer, urea (CO(NH2)2). The swelling degree results showed that the clay loading considerably reduces the water absorption capability; however, the hydrolysis process favored the urea adsorption in the hydrogel nanocomposites, increasing the load content according to the increase of the clay mass. The FTIR spectra indicated that there was incorporation of the clay with the polymeric matrix of the hydrogel and that incorporation increased the water absorption speed (indicated by the kinetic constant k). By an X-ray diffraction technique, good nanodispersion (intercalation) and exfoliation of the clay platelets in the hydrogel matrix were observed. Furthermore, the presence of the montmorillonite in the hydrogel caused the system to liberate the nutrient in a more controlled manner than that with the neat hydrogel in different pH ranges. In conclusion, excellent results were obtained for the controlled desorption of urea, highlighting the hydrolyzed hydrogels containing 50% calcic montmorillonite. This system presented the best desorption results, releasing larger amounts of nutrient and almost 200 times slower than pure urea, i.e., without hydrogel. The total values of nutrients present in the system show that this material is potentially viable for application in agriculture as a nutrient carrier vehicle. © 2013 American Chemical Society.

Antifungal applications of Ag-decorated hydroxyapatite nanoparticles

Pure hydroxyapatite (HA) and hydroxyapatite decorated with silver (HA@Ag) nanoparticles were synthesized and characterized. The antifungal effect of HA@Ag nanoparticles in a distilled water solution was evaluated against Candida albicans. The origin of the antifungal activity of the HA@Ag is also discussed. The results obtained showed that the HA nanorod morphology remained the same with Ag ions decorations on the HA structure which were deposited in the form of nanospheres. Interaction where occurred between the structure and its defect density variation in the interfacial HA@Ag and intrafacial HA region with the fungal medium resulted in antifungal activity. The reaction mechanisms involved oxygen and water adsorption which formed an active complex cluster. The decomposition and desorption of the final products as well as the electron/hole recombination process have an important role in fungicidal effects. © 2013 C. A. Zamperini et al.

Solid-phase extraction of metal ions from fuel ethanol with a nanostructured adsorbent

This work describes the synthesis and characterization of a new octakis[3-(2,2'-dipyridylamine)propyl]octasilsesquioxane (T8-Pr-DPA), and a study of the metal ion preconcentration in fuel ethanol. Batch and column experiments were conducted to investigate for the removal of heavy metal ions from fuel ethanol. The results showed that the Langmuir allowed to describe the sorption equilibrium data of the metal ions on T8-Pr-DPA in a satisfactory way. The following maximum adsorption capacities (in mmolg-1) were determined: 3.62 for Fe (III), 3.32 for Cr (III), 2.15 for Cu (II), 1.80 for Co (II), 1.62 for Pb (II), 1.32 for Ni (II) and 0.88 for Zn (II). The thermodynamic parameters for the adsorption process such as free energy of adsorption (δG), enthalpy of adsorption (δH) and entropy of adsorption (δS) were calculated. Thermodynamic parameters showed that the system has favorable enthalpic, Gibbs free energy, and entropic values. The sorption-desorption of the metal ions has made possible the development of a preconcentration and determination method of metal ions at trace level in fuel ethanol. The method of quantitative analysis for Fe, Cu, Ni and Zn in fuel ethanol by Flame AAS was validated. Several parameters have been taken into account and evaluated for the validation of method, namely: linearity, limit of detection, limit of quantification, and the relative standard deviation and accuracy. The accuracy of the method was assessed by testing analyte recovery in the fuel ethanol samples. © 2013 Elsevier B.V.

Isotermas de sorção e cinética de secagem de sementes de pomelo

The drying of grapefruit seeds, by-products from grapefruit processing, was studied at 40, 50, 60 and 70°C and at three air velocities, 0.6, 1.0 and 1.4 m s-1. Sorption isotherms of grapefruit seeds were obtained at each temperature by the static method using saturated salt solutions. The Henderson model adequately described the sorption isotherms, over the entire temperature range. Drying rates indicated that the drying of grapefruit seeds took place under the falling rate period. Effective moisture diffusivity in grapefruit seeds ranged from 4.36 × 10-10 to 6.82 × 10-10 m2 s-1. The temperature dependence of the effective diffusivity followed an Arrhenius relationship, and the activation energies were 12.23, 11.29 and 11.79 kJ mol-1 for dried grapefruit seeds under air velocities of 0.6, 1.0 and 1.4 m s-1, respectively. Three thin-layer models were used to predict the drying curves, Page, Lewis, and Henderson-Pabis model. The Page model presented the best fit for all drying air temperatures and velocities studied.

Disponibilidade de fósforo em função da aplicação de calcário e silicatos em solos oxídicos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudos dos efeitos de carga e da hidrofobicidade na interação de peptídeos antimicrobianos e membranas modelo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo por simulação computacional da interação entre polieletrólitos fracos e macroíons esféricos

Pós-graduação em Biofísica Molecular - IBILCE

Estudo por simulação computacional da interação entre polianfóteros fracos e macroíons cilíndricos

Pós-graduação em Biofísica Molecular - IBILCE

Transformação do glicerol em compostos de interesse petroquímico catalisada por zeólitas com ordem hierárquica de poros

Pós-graduação em Química - IQ