Síntese, caracterização e estudo físico-químico de nanopartículas formadas pela interação de derivados hidrofílicos de quitosana com DNA

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Síntese e caracterização de vidros teluritos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Morfologias de óxido de cobre (II) na mesoescala: síntese hidrotérmica assistida por micro-ondas, mecanismo de crescimento e atividade catalítica na reação de desidrogenação do etanol

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Induction and Morpho-Ultrastructural Analysis of Organogenic Calli of a Wild Passionfruit

This work studied a new protocol for organogenic calli induction and characterization of the morphology and ultrastructure of callogenesis in leaf explants of Passiflora gibertii N. E. Brown, a native passion fruit species from Brazil. Calli induction was performed in different growth conditions (light and dark), different MS medium salt concentrations (MS and MS half strength) and the presence or absence of coconut water. The leaf explants maintained in the dark were more responsive to bud formation. In order to reduce spending on in vitro culture, the most suitable induction medium for P. gibertii organogenesis could, therefore be the MS half strength salt concentration medium maintained in the dark. The addition of coconut water to the culture medium was essential for both calli induction and bud formation. The morphological and ultrastructural features of the organogenic calli were isodiametric cells, characterized by an organized cellular system, nucleus with prominent nucleoli, presence of starch grains and dense cytoplasm rich in endoplasmic reticulum. The scanning electron microscopy demonstrated that buds were present on these calli.

Estudo de composições vítreas no sistema ternário Ga-Ge-Te para o armazenamento de dados

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desenvolvimento e caracterização físico-química e biofarmacêutica de nano e microemulsões lipídicas de uso intravenoso contendo metildiidrojasmonato

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Metallic nanoparticles grown in the core of femtosecond laser micromachined waveguides

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Glucose biosensor based on multisegment nanowires exhibiting reversible magnetic control

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Mechanisms of SnO2 Nanoparticles Formation and Growth in Acid Ethanol Solution Derived from SAXS and Combined Raman-XAS Time-Resolved Studies

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudos das interações do peptídeo antimicrobiano Polybia MP1 com membranas modelo: mecanismo de ação e especificidade

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Functional and structural studies of the disulfide isomerase DsbC from the plant pathogen Xylella fastidiosa reveals a redox-dependent oligomeric modulation in vitro

Xylella fastidiosa is a Gram-negative bacterium that grows as a biofilm inside the xylem vessels of susceptible plants and causes several economically relevant crop diseases. In the present study, we report the functional and low-resolution structural characterization of the X. fastidiosa disulfide isomerase DsbC (XfDsbC). DsbC is part of the disulfide bond reduction/isomerization pathway in the bacterial periplasm and plays an important role in oxidative protein folding. In the present study, we demonstrate the presence of XfDsbC during different stages of X. fastidiosa biofilm development. XfDsbC was not detected during X. fastidiosa planktonic growth; however, after administering a sublethal copper shock, we observed an overexpression of XfDsbC that also occurred during planktonic growth. These results suggest that X. fastidiosa can use XfDsbC in vivo under oxidative stress conditions similar to those induced by copper. In addition, using dynamic light scattering and small-angle X-ray scattering, we observed that the oligomeric state of XfDsbC in vitro may be dependent on the redox environment. Under reducing conditions, XfDsbC is present as a dimer, whereas a putative tetrameric form was observed under nonreducing conditions. Taken together, our findings demonstrate the overexpression of XfDsbC during biofilm formation and provide the first structural model of a bacterial disulfide isomerase in solution. Structured digital abstract XfDsbC and XfDsbC bind by x ray scattering (View Interaction: 1, 2) XfDsbC and XfDsbC bind by molecular sieving (View interaction) XfDsbC and XfDsbC bind by comigration in non denaturing gel electrophoresis (View interaction) XfDsbC and XfDsbC bind by cross-linking study (View Interaction: 1, 2) XfDsbC and XfDsbC bind by dynamic light scattering (View Interaction: 1, 2)

NIR luminescent Er3+/Yb3+ co-doped SiO2-ZrO2 nanostructured planar and channel waveguides: Optical and structural properties

Optical and structural properties of planar and channel waveguides based on sol gel Er3+ and Yb3+ co-doped SiO2-ZrO2 are reported. Microstructured channels with high homogeneous surface profile were written onto the surface of multilayered densified films deposited on SiO2/Si substrates by a femtosecond laser etching technique. The densification of the planar waveguides was evaluated from changes in the refractive index and thickness, with full densification being achieved at 900 degrees C after annealing from 23 up to 500 min, depending on the ZrO2 content Crystal nucleation and growth took place together with densification, thereby producing transparent glass ceramic planar waveguides containing rare earth-doped ZrO2 nanocrystals dispersed in a silica-based glassy host Low roughness and crack-free surface as well as high confinement coefficient were achieved for all the compositions. Enhanced NIR luminescence of the Er3+ ions was observed for the Yb3+- codoped planar waveguides, denoting an efficient energy transfer from the Yb3+ to the Er3+ ion. (C) 2012 Elsevier B.V. All rights reserved.

On the diurnal cycle of urban aerosols, black carbon and the occurrence of new particle formation events in springtime Sao Paulo, Brazil

Large conurbations are a significant source of the anthropogenic pollution and demographic differences between cities that result in a different pollution burden. The metropolitan area of Sao Paulo (MASP, population 20 million) accounts for one fifth of the Brazilian vehicular fleet. A feature of MASP is the amount of ethanol used by the vehicular fleet, known to exacerbate air quality. The study describes the diurnal behaviour of the submicron aerosol and relies on total particle number concentration, particle number size distribution, light scattering and light absorption measurements. Modelled planetary boundary layer (PBL) depth and air mass movement data were used to aid the interpretation. During morning rush-hour, stagnant air and a shallow PBL height favour the accumulation of aerosol pollution. During clear-sky conditions, there was a wind shift towards the edge of the city indicating a heat island effect with implications on particulate pollution levels at the site. The median total particle number concentration for the submicron aerosol typically varied in the range 1.6 x 10(4)-3.2 x 10(4) cm(-3) frequently exceeding 4 x 10(4) cm-3 during the day. During weekdays, nucleation-mode particles are responsible for most of the particles by numbers. The highest concentrations of total particle number concentrations and black carbon (BC) were observed on Fridays. Median diurnal values for light absorption and light scattering (at 637 nm wavelength) varied in the range 12-33 Mm(-1) and 21-64 Mm(-1), respectively. The former one is equal to 1.8-5.0 mu g m(-3) of BC. The growth of the PBL, from the morning rush-hour until noon, is consistent with the diurnal cycle of BC mass concentrations. Weekday hourly median single-scattering albedo (omega(0)) varied in the range 0.59-0.76. Overall, this suggests a top of atmosphere (TOA) warming effect. However, considering the low surface reflectance of urban areas, for the given range of omega(0), the TOA radiative forcing can be either positive or negative for the sources within the MASP. On the average, weekend omega(0) values were 0.074 higher than during weekdays. During 11% of the days, new particle formation (NPF) events occurred. The analysed events growth rates ranged between 9 and 25 nm h(-1). Sulphuric acid proxy concentrations calculated for the site were less than 5% of the concentration needed to explain the observed growth. Thus, other vapours are likely contributors to the observed growth.

Novel SrTi1-xFexO3 nanocubes synthesized by microwave-assisted hydrothermal method

We report herein for the first time a facile synthesis method to obtain SrTi1-xFexO3 nanocubes by means by a microwave-assisted hydrothermal (MAH) method at 140 degrees C. The effect of iron addition on the structural and morphological properties of SrTiO3 was investigated. X-ray diffraction measurements show that all STFO samples present a cubic perovskite structure. X-ray absorption spectroscopy at Fe absorption K-edge measurements revealed that iron ions are in a mixed Fe2+/Fe3+ oxidation state and preferentially occupy the Ti4+-site. UV-visible spectra reveal a reduction in the optical gap (E-gap) of STFO samples as the amount of iron is increased. An analysis of the data obtained by field emission scanning electron microscopy points out that the nanoparticles present a cubic morphology independently of iron content. According to high-resolution transmission electron microscopy results, these nanocubes are formed by a self-assembly process of small primary nanocrystals.

Polymeric Nanoparticles as Oral Delivery Systems for Encapsulation and Release of Polyphenolic Compounds: Impact on Quercetin Antioxidant Activity & Bioaccessibility

A delivery system containing polymeric (Eudragit) nanoparticles has been developed for encapsulation and controlled release of bioactive flavonoids (quercetin). Nanoparticles were fabricated using a solvent displacement method. Particle size, morphology, and charge were measured by light scattering, electron microscopy and zeta-potential. Encapsulation efficiency (EE) and release profiles were determined using electrochemical methods. Molecular interactions within the particle matrix were characterized by X-ray diffraction, differential scanning calorimetry, and infrared spectroscopy. Antioxidant properties of free and encapsulated quercetin were analyzed by TBARS and fluorescence spectroscopy. Bioaccessibility of quercetin was evaluated using an in vitro digestion model. Relatively small (d a parts per thousand aEuro parts per thousand 370 nm) anionic polymeric nanoparticles were formed containing quercetin in a non-crystalline form (EE a parts per thousand aEuro parts per thousand 67 %). The main interaction between quercetin and Eudragit was hydrogen bonding. Encapsulated quercetin remained stable during 6 months storage and maintained its antioxidant activity. Quercetin bioaccessibility within simulated small intestinal conditions was improved by encapsulation. The knowledge obtained from this study will facilitate the rational design and fabrication of polymeric nanoparticles as oral delivery systems for encapsulation, protection, and release of bioactive compounds.