Influence of surfactant and processing conditions in the stability of oil-in-water nanoemulsions

This work evaluates the influence of the type of surfactant (Tween 20, SDS and DTAB) and processing conditions on the stability of oil-in-water nanoemulsions, measured in terms of hydrodynamic diameter (Hd), polydispersity index (PdI) and zeta potential (Zp). Nanoemulsions were prepared using high-pressure homogenization based on a 24 level factorial design. Results show that processing parameters such as homogenization pressure, surfactant concentrations and oil:water ratio significantly affected the values of Hd and PdI of nanoemulsions. The value of Hd of anionic nanoemulsions decreased (from 177 to 128 nm) with the increase of the homogenization pressure. The increase in the surfactant concentration and the decrease of the oil:water ratio lead to a decrease of Hd for the cationic nanoemulsions (from 198 to 135 nm). The increase of the oil:water ratio lead to a decrease of Hd for the non-ionic nanoemulsions (from 341 to 171 nm); this is contrary to the usual assumption that higher content in oil results in higher values of Hd. Those nanoemulsions showed a good kinetic stability (evaluated after centrifugation, heatingcooling cycles and thermal stress) upon measuring the Hd during 28 and 35 days of storage, without visual evidence of creaming and phase separation. After one year of storage the nanoemulsions produced with the anionic surfactant remained kinetically stable, without visual evidence of creaming and/or phase separation.Helder D. Silva, and Miguel A. Cerqueira (SFRH/BD/81288/2011, and SFRH/BPD/72753/2010, respectively) are the recipients of a fellowship from the Fundacao para a Ciencia e Tecnologia (FCT, Portugal). The authors would like to acknowledge to Francesco Donsi and Giovanna Ferrari from Department of Industrial Engineering, University of Salerno for helping in the viscosity and density measurements and to Rui Fernandes from IBMC, University of Porto for assistance in taking the TEM pictures. The authors thank the FCT Strategic Project PEst-OE/EQB/LA0023/2013 and the project "BioInd-Biotechnology and Bioengineering for improved Industrial and Agro-Food processes", REF.NORTE-07-0124- FEDER-000028, co-funded by the Programa Operacional Regional do Norte (ON.2 - 0 Novo Norte), QREN, FEDER. We also thank to the European Commission: BIOCAPS (316265, FP7/REGPOT-2012-2013.1). The support of EU Cost Action FA1001 is gratefully acknowledged. Also the authors acknowledge Stepan for providing the Neobee 1053 oil

Pesquisa-ação: fundamentos do planejamento e do diagnóstico em comunidades rurais.

O presente trabalho nasceu da necessidade de divulgar um aspecto operacional da metodologia da pesquisa-ação chamada de diagnóstico. O estudo tem sido realizado por uma equipe de pesquisadores, extensionistas e agricultores nos Estados da Bahia, Pernambuco e Paraíba através da Embrapa Mandioca e Fruticultura, EMATER-PB, EBDA, EMATER-PE. No Brasil, as comunidades, municípios e regiões apresentam-se de forma diferenciada, com menor ou maior complexidade. Logo, para se intervir em determinada área para promover um processo de mudanças e necessário compreender primeiro sua realidade.bitstream/item/81305/1/Pesquisa-Acao-Jose-Cerqueira-Documentos-93-2000.pd

On the Influence of Magnetic Fields on the Structure of Protostellar Jets

We here present the first results of fully three-dimensional (3-D) MHD simulations of radiative cooling pulsed (time-variable) jets for a set of parameters which are suitable for protostellar outflows. Considering different initial magnetic field topologies in approximate $equipartition$ with the thermal gas, i.e., (i) a longitudinal, and (ii) a helical field, both of which permeating the jet and the ambient medium; and (iii) a purely toroidal field permeating only the jet, we find that the overall morphology of the pulsed jet is not very much affected by the presence of the different magnetic field geometries in comparison to a nonmagnetic calculation. Instead, the magnetic fields tend to affect essentially the detailed structure and emission properties behind the shocks at the head and at the pulse-induced internal knots, particularly for the helical and toroidal geometries. In these cases, we find, for example, that the $H_\alpha$ emissivity behind the internal knots can be about three to four times larger than that of the purely hydrodynamical jet. We also find that some features, like the nose cones that often develop at the jet head in 2-D calculations involving toroidal magnetic fields, are smoothed out or absent in the 3-D calculations.Comment: 13 pages, 3 figures, Accepted by ApJ Letters after minor corrections (for high resolution figures, see http://www.iagusp.usp.br/~adriano/h.tar

A layer-by-layer approach for curcumin encapsulation for food applications

Driven by the consumers’ needs for new, healthier and safer food products, the food industry is seeking for edible systems able to encapsulate, protect and release lipophilic functional compounds. Nanoemulsion-based technology offers the methodologies for encapsulate, protect and control release, while improving the solubility and bioavailability of these compounds. The present work aimed at preparing stable curcumin nanoemulsions and multilayer nanoemulsions as potential bioactive compounds for food formulations. Curcumin nanoemulsions and multilayer nanoemulsions were prepared using high-pressure homogenization and the electrostatic layer-by-layer deposition techniques, respectively. Chitosan was used to build the first and third layers, being the second layer formed by alginate. The size stability and zeta potential studies showed that both systems were stable in time, during storage (60 days), obtaining hydrodynamic diameters of 80, 110 and 140 nm for the nanoemulsion, second and third layer, respectively. Size stability against different pH’s was also evaluated, being both nanosystems stable between the pH ranges of 2 to 12, where the pKa values of chitosan and alginate can influence the swelling and release of the multilayer nanoemulsions. Curcumin release studies showed that only curcumin nanoemulsions allowed release of this compound; results clearly showed that the addition of biopolymers layers (multilayer nanoemulsions) reinforced the stability of these structures, avoiding curcumin release. This work shows that it is possible to prepare multi-layer oil-in-water nanoemulsions through LbL technique using edible biopolymers and that this technology offers the potential to significantly improve solubility and bioavailability of bioactive compounds with different release kinetics profiles

Emission lines from rotating proto-stellar jets with variable velocity profiles. I. Three-dimensional numerical simulation of the non-magnetic case

Using the Yguazu-a three-dimensional hydrodynamic code, we have computed a set of numerical simulations of heavy, supersonic, radiatively cooling jets including variabilities in both the ejection direction (precession) and the jet velocity (intermittence). In order to investigate the effects of jet rotation on the shape of the line profiles, we also introduce an initial toroidal rotation velocity profile, in agreement with some recent observational evidence found in jets from T Tauri stars which seems to support the presence of a rotation velocity pattern inside the jet beam, near the jet production region. Since the Yguazu-a code includes an atomic/ionic network, we are able to compute the emission coefficients for several emission lines, and we generate line profiles for the H, [O I]6300, [S II]6716 and [N II]6548 lines. Using initial parameters that are suitable for the DG Tau microjet, we show that the computed radial velocity shift for the medium-velocity component of the line profile as a function of distance from the jet axis is strikingly similar for rotating and non-rotating jet models. These findings lead us to put forward some caveats on the interpretation of the observed radial velocity distribution from a few outflows from young stellar objects, and we claim that these data should not be directly used as a doubtless confirmation of the magnetocentrifugal wind acceleration models.Comment: 15 pages, 8 figures. Accepted to publication in Astronomy and Astrophysic