Shape-controlled continuous synthesis of metal nanostructures

A segmented flow-based microreactor is used for the continuous production of faceted nanocrystals. Flow segmentation is proposed as a versatile tool to manipulate the reduction kinetics and control the growth of faceted nanostructures; tuning the size and shape. Switching the gas from oxygen to carbon monoxide permits the adjustment in nanostructure growth from 1D (nanorods) to 2D (nanosheets). CO is a key factor in the formation of Pd nanosheets and Pt nanocubes; operating as a second phase, a reductant, and a capping agent. This combination confines the growth to specific structures. In addition, the segmented flow microfluidic reactor inherently has the ability to operate in a reproducible manner at elevated temperatures and pressures whilst confining potentially toxic reactants, such as CO, in nanoliter slugs. This continuous system successfully synthesised Pd nanorods with an aspect ratio of 6; thin palladium nanosheets with a thickness of 1.5 nm; and Pt nanocubes with a 5.6 nm edge length, all in a synthesis time as low as 150 s.

Tetragonal-cubic phase boundary in nanocrystalline ZrO(2)-Y(2)O(3) solid solutions synthesized by gel-combustion

By means of synchrotron X-ray powder diffraction (SXPD) and Raman spectroscopy, we have detected, in a series of nanocrystalline and compositionally homogeneous ZrO(2)-Y(2)O(3) solid solutions, the presence at room temperature of three different phases depending on Y(2)O(3) content, namely two tetragonal forms and the cubic phase. The studied materials, with average crystallite sizes within the range 7-10 nm, were synthesized by a nitrate-citrate gel-combustion process. The crystal structure of these phases was also investigated by SXPD. The results presented here indicate that the studied nanocrystalline ZrO(2)-Y(2)O(3) solid solutions exhibit the same phases reported in the literature for compositionally homogeneous materials containing larger (micro)crystals. The compositional boundaries between both tetragonal forms and between tetragonal and cubic phases were also determined. (C) 2011 Elsevier B.V. All rights reserved.

Infrared luminescence, thermoluminescence and defect centres in Er and Yb co-doped ZnAl(2)O(4) phosphor

Er and Yb co-doped ZnAl(2)O(4) phosphors were prepared by solution combustion synthesis and the identification of Er and Yb were done by energy-dispersive X-ray analysis (EDX) studies. A luminescence at 1.5 mu m, due to the (4)I(13/2) ->(4)I(15/2) transition, has been studied in the NIR region in Er and Yb co-doped ZnAl(2)O(4) phosphors upon 980 nm CW pumping. Er-doped ZnAl(2)O(4) exhibits two thermally stimulated luminescence (TSL) peaks around 174A degrees C and 483A degrees C, while Yb co-doped ZnAl(2)O(4) exhibits TSL peaks around 170A degrees C and 423A degrees C. Electron spin resonance (ESR) studies were carried out to identify defect centres responsible for TSL peaks observed in the phosphors. Room temperature ESR spectrum appears to be a superposition of two distinct centres. These centres are assigned to an O(-) ion and F(+) centre. O(-) ion appears to correlate with the 174A degrees C TSL peak and F(+) centre appears to relate with the high temperature TSL peak at 483A degrees C in ZnAl(2)O(4):Er phosphor.

Glia-Pinealocyte Network: The Paracrine Modulation of Melatonin Synthesis by Tumor Necrosis Factor (TNF)

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

Biosurfactant synthesis by Pseudomonas aeruginosa LBI isolated from a hydrocarbon-contaminated site

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

Structural biology of membrane-acting peptides: Conformational plasticity of anticoccidial peptide PW2 probed by solution NMR

The bottleneck for the complete understanding of the structure-function relationship of flexible membrane-acting peptides is its dynamics. At the same time, not only the structure but also the dynamics are the key points for their mechanism of action. Our model is PW2, a TRP-rich, cationic peptide selected from phage display libraries that shows anticoccidial activity against Eimeria acervulina. In this manuscript we used a combination of several NMR techniques to tackle these difficulties. The structural features of the membrane-acting peptide PW2 was studied in several membrane mimetic environments: we compared the structural features of PW2 in SDS and DPC micelles, that were reported earlier, with the structure properties in different lipid vesicles and the peptide free in water. We were able to unify the structural information obtained in each of these systems. The structural constraints of the peptide free in water were fundamental for the understanding of plasticity necessary for the membrane interaction. Our data suggested that the WWR sequence is the region responsible for anchoring the peptide to the interfaces, and that this same region displays some degree of conformational order in solution. For PW2, we found that affinity is related to the aromatic region, by anchoring the peptide to the membrane, and specificity is related to the N- and C-termini, which are able to accommodate in the membrane due to its plasticity. (C) 2007 Elsevier B.V. All rights reserved.

Synthesis by the polymeric precursor method and characterization of undoped and Sn, Cr and V-doped ZrTiO4

In this work, zirconium titanate doped with 0. 1, 0.2, and 0.4 mole% of tin, chromium and vanadium was synthesized by the polymeric precursors method and characterized by thermal analysis (TG/DTA), X-ray diffraction (XRD), nitrogen adsorption and scanning electronic microscopy (SEM). The powder presented two mass losses attributed to the exit of water and to the pyrolysis of the organic material. The surface area reduction observed from 500 degrees C indicates the beginning of the sintering process. All the dopants led to changes in the lattice parameters and to the decrease of both crystallite size and particle size. (c) 2005 Elsevier B.V. All rights reserved.

Vanadato de bismuto sintetizado por combustão em solução na presença de diferentes combustíveis: síntese, caracterização e estudo da atividade fotocatalítica

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

Effect of Eu substitution on the crystallographic and magnetic properties of the BiMn2O5 oxide obtained by urea combustion

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

Synthesis by a chemical method and characterization of CaZrO3 powders: Potential application as humidity sensors

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Phototherapy up-regulates dentin matrix proteins expression and synthesis by stem cells from human-exfoliated deciduous teeth

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

Effect of LPS treatment on the viability and chemokine synthesis by epithelial cells and gingival fibroblasts

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

Well-Defined Poly(4-vinylbenzocyclobutene): Synthesis by Living Anionic Polymerization and Characterization

Living anionic polymerization of 4-vinylbenzocylobutene was performed in benzene at room temperature using sec-butyllithium as the initiator. Results of the kinetic studies indicated the termination- and transfer-free nature of the polymerization. Homopolymers with predictable molecular weights and narrow molecular weight distributions were produced, excluding the interference of the cyclobutene rings during initiation and propagation. Thermogravimetric analysis of poly(4-vinylbenzocyclobutene) in air showed a small weight gain at ~200 °C, a rapid decomposition at ~455 °C, and a gradual decomposition at ~566 °C. This behavior was attributed to the formation of radicals from the pendent benzocyclobutene functionality through o-quinodimethane intermediates and simultaneous decomposition/cross-linking reactions at high temperature. The living nature of the polymerization was also examined via sequential copolymerization with butadiene to form diblock copolymers.

Microcystis aeruginosa lipids as feedstock for biodiesel synthesis by enzymatic route

The cyanobacterium Microcystis aeruginosa strain NPCD-1, isolated from sewage treatment plant and characterized as a non-microcystin producer by mass spectrometry and molecular analysis, was found to be a source of lipid when cultivated in ASM-1 medium at 25 degrees C under constant white fluorescent illumination (109 mu mol photon m(-2) s(-1)). In these conditions, biomass productivity of 46.92 +/- 3.84 mg L-1 day(-1) and lipid content of 28.10 +/- 1.47% were obtained. Quantitative analysis of fatty acid methyl esters demonstrated high concentration of saturated fatty acids (50%), palmitic (24.34%) and lauric (13.21%) acids being the major components. The remaining 50% constituting unsaturated fatty acids showed higher concentrations of oleic (26.88%) and linoleic (12.53%) acids. The feasibility to produce biodiesel from this cyanobacterial lipid was demonstrated by running enzymatic transesterification reactions catalyzed by Novozym (R) 435 and using palm oil as feedstock control. Batch experiments were carried out using tert-butanol and iso-octane as solvent. Results showed similarity on the main ethyl esters formed for both feedstocks. The highest ethyl ester concentration was related to palmitate and oleate esters followed by laurate and linoleate esters. However, both reaction rates and ester yields were dependent on the solvent tested. Total ethyl ester concentrations varied in the range of 44.24-67.84 wt%, corresponding to ester yields from 80 to 100%. Iso-octane provided better solubility and miscibility, with ester yield of 98.10% obtained at 48 h for reaction using the cyanobacterium lipid, while full conversion was achieved in 12 h for reaction carried out with palm oil. These results demonstrated that cyanobacterial lipids from M. aeruginosa NPCD-1 have interesting properties for biofuel production. (c) 2012 Elsevier B.V. All rights reserved.

Potential Contribution of Translational Factors to Triiodo-L-Thyronine-Induced Insulin Synthesis by Pancreatic Beta Cells

Background: Thyroid hormones (THs) are known to regulate protein synthesis by acting at the transcriptional level and inducing the expression of many genes. However, little is known about their role in protein expression at the post-transcriptional level, even though studies have shown enhancement of protein synthesis associated with mTOR/p70S6K activation after triiodo-l-thyronine (T3) administration. On the other hand, the effects of TH on translation initiation and polypeptidic chain elongation factors, being essential for activating protein synthesis, have been poorly explored. Therefore, considering that preliminary studies from our laboratory have demonstrated an increase in insulin content in INS-1E cells in response to T3 treatment, the aim of the present study was to investigate if proteins of translational nature might be involved in this effect. Methods: INS-1E cells were maintained in the presence or absence of T3 (10(-6) or 10(-8) M) for 12 hours. Thereafter, insulin concentration in the culture medium was determined by radioimmunoassay, and the cells were processed for Western blot detection of insulin, eukaryotic initiation factor 2 (eIF2), p-eIF2, eIF5A, EF1A, eIF4E binding protein (4E-BP), p-4E-BP, p70S6K, and p-p70S6K. Results: It was found that, in parallel with increased insulin generation, T3 induced p70S6K phosphorylation and the expression of the translational factors eIF2, eIF5A, and eukaryotic elongation factor 1 alpha (eEF1A). In contrast, total and phosphorylated 4E-BP, as well as total p70S6K and p-eIF2 content, remained unchanged after T3 treatment. Conclusions: Considering that (i) p70S6K induces S6 phosphorylation of the 40S ribosomal subunit, an essential condition for protein synthesis; (ii) eIF2 is essential for the initiation of messenger RNA translation process; and (iii) eIF5A and eEF1A play a central role in the elongation of the polypeptidic chain during the transcripts decoding, the data presented here lead us to suppose that a part of T3-induced insulin expression in INS-1E cells depends on the protein synthesis activation at the post-transcriptional level, as these proteins of the translational machinery were shown to be regulated by T3.