Hydrothermal assisted synthesis of iron oxide-based magnetic silica spheres and their performance in magnetophoretic water purification

Porous Magnetic Silica (PMS) spheres of about 400 nm diameter were synthesised by one-pot process using the classical Stӧber method combined with hydrothermal treatment. Maghemite nanoparticles (γ-Fe2O3) were used as fillers and cetyltrimethylammonium bromide (CTAB) was used as templating agent. The application of the hydrothermal process (120 °C during 48 h) before the calcination leads to the formation of homogeneous and narrow size distribution PMS spheres. X-ray diffraction patterns (XRD), Infrared measurements (FTIR) and Transmission Electron microscopy (TEM) methods were used to determine the composition and morphology of the obtained PMS spheres. The results show a homogeneous distribution of the γ-Fe2O3 nanoparticles in the silica matrix with a “hollow-like” morphology. Magnetophoresis measurements at 60 T m−1 show a total separation time of the PMS spheres suspension of about 16 min. By using this synthesis method, the limitation of the formation of silica spheres without incorporation of magnetic nanoparticles is overcome. These achievements make this procedure interesting for industrial up scaling. The obtained PMS spheres were evaluated as adsorbents for Ni2+ in aqueous solution. Their adsorption capacity was compared with the adsorption capacity of magnetic silica spheres obtained without hydrothermal treatment before calcination process. PMS spheres show an increase of the adsorption capacity of about 15% of the initial dissolution of Ni2+ without the need to functionalize the silica surface.Fundação para a Ciência e a Tecnologia (FCT

The effect of nanotube surface oxidation in the electrical response of MWCNT/PVDF nanocomposites

Carbon nanotubes / poly(vinylidene fluoride) composites were prepared using CNT with different oxidation and thermal treatments. The oxidation procedure leads to CNT with the most acidic characteristics that lower the degree of crystallinity of the polymer and contribute to a large increase of the dielectric constant. The surface treatments, in general, increase percolation threshold and decrease conductivity, but, on the other hand, are able to promote the nucleation of the electroactive phase of the polymer, which is suitable for the use of PVDF in sensors, actuators and other smart materials applications. Finally, the surface treatments do not seem to affect CNT interaction among them, reaching similar degrees of dispersion in all cases, as shown by the SEM results. The maximum value of the dielectric constant is ~630. It is demonstrated that the composite conductivity can be attributed to a hopping mechanism that is strongly affected by the surface treatment of the CNT.The authors thank the Fundacao para a Ciencia e a Tecnologia (FCT), Portugal, for financial support through the projects PTDC/CTM/69316/2006 and NANO/NMed-SD/0156/2007), and CIENCIA 2007 program for S.A.C.; V. S., J.S. and J.N.P. also thank FCT for the SFRH/BPD/63148/2009, SFRH/BD/60623/2009 and SFRH/BD/66930/2009 grants

Efecto de la intensidad de diodos electroluminosos y fotoperiodo en la optimización de la producción de biomasa de Spirulina (Arthrospira)

Biomass (ф) production from Spirulina sp. batch cultures was optimized in laboratory scale photobioreactors (LPB) of 0.2 L, by the effect of X1: intensity of light emitting diodes (LEDs) and X2: photoperiod, between 1.25-41.7 klux and 12/12-24/0 hours of light/dark (L/D) respectively using a central composite rotational design (CCRD) and response surface methodology (RSM). The hydraulic characteristics and ф value from Spirulina batch cultures were also evaluated in a closed-loop channel photobioreactor open to the atmosphere (PB-CLOA) by the effect of the lighting LED of 8.3±1.9 klux and photoperiod of 12/12 and 24/0 h L/D. Two optimal zones of ф in LPB were identified, both with a 21.5 klux LED intensity and photoperiod relationship of 12/2 and 24/0 h L/D, with values of 1.65 and 1.62 ф respectively. The mathematical model which indicated the optimal zones was of 2nd order, which had a high significance (p = 0.000396 < 0.05) achieving a predictive value of R2 = 0.92. In the PB-CLOA, the cultivation of Spirulina sp. with photoperiod of 12/12 h L/D, showed a ф value of 0.72, a more rapid adaptation of λ = 4.62 h, a higher specific growth rate of μmax=0.033 h-1 and reduced time energy consumption of 74.05 h; compared to culture developed with photoperiod 24/0 h L/D. The PB-CLOA hydraulic parameters were: operation volume 2.5 L, flow velocity 0.26 m/s, numbers of Reynolds (Re) 15488, Froude (Fr) 0.60 and Vedernikov (Ved) 0.90.Se optimizó la producción de biomasa (ф) de cultivos batch de Spirulina sp. en fotobiorreactores a escala de laboratorio (FBL) de 0,2 L, por efecto de X1: intensidad de diodos electroluminosos (LED’s) entre 1,25 a 41,7 klux y X2: fotoperiodo de12/12 a 24/0, h de luz/h de oscuridad (L/O) utilizando un diseño compuesto central rotacional (DCCR) y metodología de superficie de respuesta (MSR). Asimismo, se evaluaron las características hidráulicas y el valor ф de un cultivo batch de Spirulina en un fotobiorreactor de canal bucle cerrado abierto a la atmósfera (FB-BCAA) por efecto de la iluminación LED de 8,3±1,9 klux y fotoperiodos de 12/12 y 24/0 h L/O. En los FBL se encontró dos zonas óptimas de ф, ambas con una intensidad LED de 21,5 klux y fotoperiodos 12/12 y 24/0 h L/O, siendo los valores ф de 1,65 y 1,62 respectivamente. El modelo matemático que indicó estas zonas fue de segundo orden (p = 0,000396 < 0,05) con una consistencia de predicción de R² = 0,92. En el FB-BCAA, el cultivo de Spirulina sp. con fotoperiodo de 12/12 h L/O, mostró un valor ф de 0,72, una adaptación más rápida de λ = 4,62 h, una mayor velocidad específica de crecimiento de μmax= 0,033 h-1 y menor tiempo de consumo de energía de 74,05 h; comparado con el cultivo desarrollado con fotoperiodo 24/0 h L/O. Los parámetros hidráulicos del FB-BCAA fueron: volumen de operación 2,5 L, velocidad de flujo 0,26 m/s, números de Reynolds (Re) 15488, Froude (Fr) 0,60 y Vedernikov (Ved) 0,90

New FOCUS results on charm mixing and CP violation

We present a summary of recent results on CP violation and mixing in the charm quark sector based on a high statistics sample collected by photoproduction experiment FOCUS (E831 at Fermilab). We have measured the difference in lifetimes for the $D^0$ decays: $D^0 \to K^-\pi^+$ and $D^0 \to K^-K^+$. This translates into a measurement of the $y_{CP}$ mixing parameter in the \d0d0 system, under the assumptions that $K^-K^+$ is an equal mixture of CP odd and CP even eigenstates, and CP violation is negligible in the neutral charm meson system. We verified the latter assumption by searching for a CP violating asymmetry in the Cabibbo suppressed decay modes $D^+ \to K^-K^+\pi^+$, $D^0 \to K^-K^+$ and $D^0 \to \pi^-\pi^+$. We show preliminary results on a measurement of the branching ratio $\Gamma(D^{*+}\to \pi^+ (K^+\pi^-))/\Gamma(D^{*+}\to \pi^+ (K^-\pi^+))$.Comment: 9 pages, 6 figures, requires espcrc2.sty. Presented by S.Bianco at CPConf2000, September 2000, Ferrara (Italy). In this revision, fixed several stylistic flaws, add two significant references, fixed a typo in Tab.

Sugerencias para mejorar la regulación chilena de manipulación de vertebrados terrestres en poblaciones naturales en el contexto de investigaciones científicas

In Chile, the manipulation for scientific purposes of terrestrial vertebrates from natural populations is conducted previous authorization of the Agricultural and Livestock Service and various Bioethics Committees. Obtaining such authorizations is becoming increasingly complex. The procedures do not fit the reality of scientific work, and they seem to be based on unjustified assessments of the effects of animal handling on natural populations. The aim of this commentary is to initiate a discussion in order to establish a norm of scientific manipulation of terrestrial vertebrates adjusted to biological reality and that does not interfere with scientific research.La manipulación con fines científicos de vertebrados terrestres en poblaciones naturales chilenas se debe realizar previa autorización del SAG y de Comités de Bioética institucionales. Obtener dichas autorizaciones es cada vez más complejo; los trámites no se adecúan al quehacer científico ni al conocimiento sobre el efecto de la manipulación en las poblaciones naturales. El objetivo de este comentario es contribuir a una discusión en pos del establecimiento de una normativa de manipulación científica de vertebrados terrestres ajustada a la realidad biológica y que no entorpezca la investigación científica

The Milky Way Bulge: Observed properties and a comparison to external galaxies

The Milky Way bulge offers a unique opportunity to investigate in detail the role that different processes such as dynamical instabilities, hierarchical merging, and dissipational collapse may have played in the history of the Galaxy formation and evolution based on its resolved stellar population properties. Large observation programmes and surveys of the bulge are providing for the first time a look into the global view of the Milky Way bulge that can be compared with the bulges of other galaxies, and be used as a template for detailed comparison with models. The Milky Way has been shown to have a box/peanut (B/P) bulge and recent evidence seems to suggest the presence of an additional spheroidal component. In this review we summarise the global chemical abundances, kinematics and structural properties that allow us to disentangle these multiple components and provide constraints to understand their origin. The investigation of both detailed and global properties of the bulge now provide us with the opportunity to characterise the bulge as observed in models, and to place the mixed component bulge scenario in the general context of external galaxies. When writing this review, we considered the perspectives of researchers working with the Milky Way and researchers working with external galaxies. It is an attempt to approach both communities for a fruitful exchange of ideas.Comment: Review article to appear in "Galactic Bulges", Editors: Laurikainen E., Peletier R., Gadotti D., Springer Publishing. 36 pages, 10 figure

Latin American consumption of major food groups: Results from the ELANS study

Background The Latin American (LA) region is still facing an ongoing epidemiological transition and shows a complex public health scenario regarding non-communicable diseases (NCDs). A healthy diet and consumption of specific food groups may decrease the risk of NCDs, however there is a lack of dietary intake data in LA countries. Objective Provide updated data on the dietary intake of key science-based selected food groups related to NCDs risk in LA countries. Design ELANS (Latin American Study of Nutrition and Health) is a multicenter cross-sectional study assessing food consumption from an urban sample between15 to 65 years old from 8 LA countries (Argentina, Brazil, Chile, Colombia, Costa Rica, Ecuador, Peru, and Venezuela). Two 24-HR were obtained from 9, 218 individuals. The daily intake of 10 food groups related to NCDs risk (fruits; vegetables; legumes/beans; nuts and seeds; whole grains products; fish and seafood; yogurt; red meat; processed meats; sugar-sweetened beverages (ready-to-drink and homemade)) were assessed and compared to global recommendations. Results Only 7.2% of the overall sample reached WHO's recommendation for fruits and vegetables consumption (400 grams per day). Regarding the dietary patterns related to a reduced risk of NCDs, among the overall sample legumes and fruits were the food groups with closer intake to the recommendation, although much lower than expected (13.1% and 11.5%, respectively). Less than 3.5% of the sample met the optimal consumption level of vegetables, nuts, whole grains, fish and yogurt. Largest country-dependent differences in average daily consumption were found for legumes, nuts, fish, and yogurt. Mean consumption of SSB showed large differences between countries. Conclusion Diet intake quality is deficient for nutrient-dense food groups, suggesting a higher risk for NCDs in the urban LA region in upcoming decades. These data provide relevant and up-to-date information to take urgent public health actions to improve consumption of critically foods in order to prevent NCDs. Copyright