Produção de pellets livres e imobilizados e mecanismo de solubilização de fosfatos inorgânicos por Aspergillus niger

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Absence of the Parasite Escovopsis in Fungus Garden Pellets Carried by Gynes of Atta sexdens

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Non ohmic gigahertz conductivity in pressed pellets of ClO4 doped poly(3-methylthiophene)

ESR measurements In pressed pellets of doped Poly(3-Methylthiophene)(P3MT) were performed at 10 K and 50 K after cooling the system slowly from room temperature to 110 K, quenching to 77 K and then to 10 K. ESR line asymmetry (A/B) as a function of microwave power was observed and 9.4 GHz conductivity was obtained from Dyson's theory. The data is discussed in terms of Charge-Density Wave (CDW) depinning. At 50 K the threshold electric field is estimated to be less than 1 V/cm. At 10 K a subtle pinning of the CDW was observed around 15 mW.

Plastic pellets as oviposition site and means of dispersal for the ocean-skater insect Halobates

Microplastics are omnipresent in the oceans and generally have negative impacts on the biota. However, flotsam may increase the availability of hard substrates, which are considered a limiting resource for some oceanic species, e.g. as oviposition sites for the ocean insect Halobates. This study describes the use of plastic pellets as an oviposition site for Halobates micans and discusses possible effects on its abundance and dispersion. Inspection of egg masses on stranded particles on beaches revealed that a mean of 24% (from 0% to 62%) of the pellets bore eggs (mean of 5 and max. of 48 eggs per pellet). Most eggs (63%) contained embryos, while 37% were empty egg shells. This shows that even small plastic particles are used as oviposition site by H. micans, and that marine litter may have a positive effect over the abundance and dispersion of this species. (C) 2012 Elsevier Ltd. All rights reserved.

Physicochemical and dissolution profile characterization of pellets containing different binders obtained by the extrusion-spheronization process

With the purpose of evaluating the behavior of different polymers employed as binders in small-diameter pellets for oral administration, we prepared formulations containing paracetamol and one of the following polymers: PVP, PEG 1500, hydroxypropylmethylcellulose and methylcellulose, and we evaluated their different binding properties. The pellets were obtained by the extrusion/spheronization process and were subsequently subjected to fluid bed drying. In order to assess drug delivery, the United States Pharmacopeia (USP) apparatus 3 (Bio-Dis) was employed, in conjunction with the method described by the same pharmacopeia for the dissolution of paracetamol tablets (apparatus 1). The pellets were also evaluated for granulometry, friability, true density and drug content. The results indicate that the different binders used are capable of affecting production in different ways, and some of the physicochemical characteristics of the pellets, as well as the dissolution test, revealed that the formulations acted like immediate-release products. The pellets obtained presented favorable release characteristics for orally disintegrating tablets. USP apparatus 3 seems to be more adequate for discriminating among formulations than the basket method.

In vitro drug permeation from chitosan pellets

The purpose of this study was to prepare and characterize coated pellets for controlled drug delivery. The influence of chitosan (CS) in pellets was evaluated by swelling, in vitro drug release and intestinal permeation assays. Pellets were coated with an enteric polymer, Kollicoat (R) MAE 30 DP, in a fluidized-bed apparatus and the coating formulations were based on a factorial design. Metronidazole (MT) released from coated and uncoated pellets were assessed by dissolution method using Apparatus I. Intestinal permeation was evaluated by everted intestinal sac model in rats, used to study the absorption of MT from coated pellets containing CS or not through the intestinal tissue. Although the film coating avoided drug dissolution in gastric medium, the overall drug release and intestinal permeation were dependent on the presence of CS. Thus, pellets containing CS show potential as a system for controlled drug delivery. (C) 2011 Elsevier Ltd. All rights reserved.

Effects of laser focusing and fluence on the analysis of pellets of plant materials by laser-induced breakdown spectroscopy

The effects of laser focusing and fluence on LIBS analysis of pellets of plant leaves was evaluated. A Q-switched Nd:YAG laser (5ns, 10Hz, 1064nm) was used and the emission signals were collected by lenses into an optical fiber coupled to a spectrometer with Echelle optics and ICCD. Data were acquired from the accumulation of 20 laser pulses at 2.0 mu s delay and 5.0 mu s integration time gate. The emission signal intensities increased with both laser fluence and spot size. Higher sensitivities for Ca, K, Mg, P, Al, B, Cu, Fe, Mn, and Zn determinations were observed for fluences in the range from 25 to 60Jcm(-2). Coefficients of variation of site-to-site measurements were generally lower than 10% (n=30 sites, 20 laser pulses/site) for a fluence of 50Jcm(-2) and 750 mu m spot size. For most elements, there is an indication that accuracy is improved with higher fluences. (C) 2012 Elsevier B.V. All rights reserved.

Investigation of different shellac grades and improvement of release from air suspension coated pellets

Shellac is the purified product of the natural polymer Lac. Shellac types, from different origins and with different ages, all purified by the solvent extraction process were compared in this study. Their physicochemical properties acid value, glass transition temperatures, color numbers and molecular sizes were determined. Metoprolol tartrate pellets were coated by air suspension coating with these different grades of shellac. Two coating levels 20% w/w and 25% w/w were applied and then subjected to in vitro dissolution testing. Enteric resistance was achieved for all tested brands for the two coating levels. At pH 6.8, 7.2 and 7.4, significant variations were obvious between the brands. rnMoreover the molecular size of shellac has a pronounced effect in that shellac types with larger molecular size show a higher and faster release than others, while the one with the smaller molecular size show the opposite effect on the release of metoprolol.rnIn this study commercially available ready for use aqueous shellac solutions (SSB AQUAGOLD), which are based on shellac SSB 57 (Dewaxed Orange Shellac, Bysakhi-Ber type refined in a solvent extraction process), with different manufacturing dates were used. rnTo improve the enteric coating properties of films from aqueous shellac solutions, different aqueous polymeric solutions of hydroxypropyl methylcellulose (HPMC), hydroxypropyl cellulose (HPC), carboyxmethyl cellulose (CMC), gum arabic and polysaccharides (Pullulan®) were used. These water soluble polymers will act as pore formers to enhance drug release from pellets coated with the combination of shellac and these polymers. The influence of these polymers on the gloss of the shellac films, mechanical properties of the films and drug release from metoprolol tartrate pellets were studied.rnThe potential of ethanol to alter the rate of drug release from shellac coated pellets was assessed by using a modified in vitro dose dumping in alcohol (DDA) method and the test concluded that shellac coated dosage forms can be co-administered with alcohol beverages containing ≤ 5% with no effect of alcohol on the shellac coat.rnPellets coated with shellac sodium salts, showed higher release rates than pellets coated with shellac as ammonium salt forms. rn

Fecal pellets flux at DYFAMED sediment traps

Because zooplankton feces represent a potentially important transport pathway of surface-derived organic carbon in the ocean, we must understand the patterns of fecal pellet abundance and carbon mobilization over a variety of spatial and temporal scales. To assess depth-specific water column variations of fecal pellets on a seasonal scale, vertical fluxes of zooplankton fecal pellets were quantified and their contribution to mass and particulate carbon were computed during 1990 at 200, 500, 1000, and 2000 m depths in the open northwestern Mediterranean Sea as part of the French-JGOFS DYFAMED Program. Depth-averaged daily fecal pellet flux was temporally variable, ranging from 3.04 * 10**4 pellets m**2/d in May to a low of 6.98 * 10**2 pellets m**2/d in September. The peak flux accounted for 50% of the integrated annual flux of fecal pellets and 62% of pellet carbon during only two months in mid-spring (April and May). Highest numerical fluxes were encountered at 1000 m, suggesting fecal pellet generation well below the euphotic zone. However, there was a trend toward lower pellet carbon with increasing depth, suggesting bacterial degradation or in situ repackaging as pellets sink through the water column. At 500 m, both the lowest pellet numerical abundance and carbon flux were evident during the spring peak. Combined with data indicating that numerical and carbon fluxes are dominated at 500 m by a distinct type of pellet found uniquely at this depth, these trends suggest the presence of an undescribed mid-water macro-zooplankton or micro-nekton community. Fecal pellet carbon flux was highest at 200 m and varied with depth independently of overall particulate carbon, which was greatest at 500 m. Morphologically distinct types of pellets dominated the numerical and carbon fluxes. Small elliptical and spherical pellets accounted for 88% of the numerical flux, while larger cylindrical pellets, although relatively rare (<10%), accounted for almost 40% of the overall pellet carbon flux. Cylindrical pellets dominated the pellet carbon flux at all depths except 500 m, where a large subtype of elliptical pellet, found only at that depth, was responsible for the majority of pellet carbon flux. Overall during 1990, fecal pellets were responsible for a depth-integrated annual average flux of 1.03 mgC/m**2/d, representing 18% of the total carbon flux. The proportion of vertical carbon flux attributed to fecal pellets varied from 3 to 35%, with higher values occurring during periods when the water column was vertically mixed. Especially during these times, fecal pellets are a critical conveyor of carbon to the deep sea in this region.

Producción y comercialización de cubos y pellets de alfalfa : un análisis desde la nueva economía institucional

El desarrollo de los mercados en el ámbito global, hace pensar en la actualidad sobre la existencia de un consumidor global, preocupado por demandar no sólo calidad, sino también seguridad en los productos que consume. Esta nueva característica de los consumidores, abre muchas posibilidades para el desarrollo de bienes y servicios con características que aporten una cuota de valor diferencial, sobre la cual resulte posible sustentar estrategias de negocios que hagan hincapié en esta diferenciación. Este tipo de estrategias, por lo general, se encontrarán sustentadas por productos cuyos procesos involucran activos de elevada especificidad y, en este punto, se torna importante poseer un eficiente diseño organizacional que los proteja de grandes pérdidas de valor. En lo que respecta al mercado de pellets y cubos de alfalfa en particular, donde se proyecta una demanda global creciente, y en el que la Argentina tiene ventajas comparativas a partir de su enorme potencial para el desarrollo de alfalfares de calidad premium, que le permitirían obtener un producto con un diferencial de calidad reconocido en el mercado internacional, surge como interrogante a investigar, si el negocio de pellets y cubos de alfalfa en la Argentina encuentra fortalezas para poder aprovechar las oportunidades que ofrece el mercado mundial y cuáles son las claves a considerar para contar con un diseño organizacional que permita el desarrollo de este negocio. La metodología de estudio consistió, por un lado, en una recopilación de información de fuentes primarias y secundarias, para estudiar el mercado en general y el ambiente comercial en particular, y por otro, en el desarrollo de un análisis a partir del Modelo de Tres Vías de Joskow. A partir del estudio se concluyó que para aprovechar las oportunidades en este negocio, es necesario contar con un diseño organizacional en el que coexistan diferentes formas de gobernancia. De esta forma, y con el objeto de proteger a los activos específicos en su conjunto, se observó que para la producción es necesario adoptar una estructura de gobernancia que tendiera a la integración vertical, mientras que para la comercialización se debe combinar una estructura de gobernancia híbrida que contenga salvaguardas, cuando ésta se orienta al mercado externo, con una estructura de gobernancia regida por el mercado para cuando se comercialice dentro de la Argentina

Production, oxygen uptake, and sinking velocity of copepod fecal pellets originated from the central North Sea

Production, oxygen uptake, and sinking velocity of copepod fecal pellets egested by Temora longicornis were measured using a nanoflagellate (Rhodomonas sp.), a diatom (Thalassiosira weissflogii), or a coccolithophorid (Emiliania huxleyi) as food sources. Fecal pellet production varied between 0.8 pellets ind**-1 h**-1 and 3.8 pellets ind**-1 h**-1 and was significantly higher with T. weissflogii than with the other food sources. Average pellet size varied between 2.2 x 10**5 µm**3 and 10.0 x 10**5 µm**3. Using an oxygen microsensor, small-scale oxygen fluxes and microbial respiration rates were measured directly with a spatial resolution of 2 µm at the interface of copepod fecal pellets and the surrounding water. Averaged volume-specific respiration rates were 4.12 fmol O2 µm**-3 d**-1, 2.86 fmol O2 µm**-3 d**-1, and 0.73 fmol O2 µm**-3 d**-1 in pellets produced on Rhodomonas sp., T. weissflogii, and E. huxleyi, respectively. The average carbon-specific respiration rate was 0.15 d**-1 independent on diet (range: 0.08-0.21 d**-1). Because of ballasting of opal and calcite, sinking velocities were significantly higher for pellets produced on T. weissflogii (322 +- 169 m d**-1) and E. huxleyi (200 +- 93 m d**-1) than on Rhodomonas sp. (35 +- 29 m d**-1). Preservation of carbon was estimated to be approximately 10-fold higher in fecal pellets produced when T. longicornis was fed E. huxleyi or T. weissflogii rather than Rhodomonas sp. Our study directly demonstrates that ballast increases the sinking rate of freshly produced copepod fecal pellets but does not protect them from decomposition.