Dietary lysine requirement of juvenile pacu Piaractus mesopotamicus (Holmberg, 1887)

Lysine is the reference essential amino acid in fish feeds and usually the most limiting amino acid in feedstuffs. The dietary lysine requirement of juvenile pacu Piaractus mesopotamicus (4.3 g) was determined using five isonitrogenous (32% CP) test diets containing graded levels of lysine (0.9, 1.17, 1.44, 1.69 and 1.96% of dry diet) fed three times a day to four groups of 18 fish for 74 days. Growth, body composition, nutrient retention and hematological parameters of pacu were analyzed. Analysis of variance showed that all growth performance parameters were significantly affected by dietary treatments. The lysine requirements estimated using regression analysis for maximum weight gain and feed efficiency were 1.45 and 1.51% of dry diet, respectively. Nitrogen retention efficiency increased with increasing levels of dietary lysine up to 1.43% (p<0.05). Whole-body protein increased (p<0.05) and whole-body lipid decreased (p<0.05) with increasing dietary lysine level. Thus, the lysine requirement of juvenile pacu was estimated as being 1.4-1.5% of dry diet or 4.4-4.7% of dietary protein. (c) 2009 Elsevier B.V. All rights reserved.

Tripalmitin and monoacylglycerols as modifiers in the crystallisation of palm oil

An exhaustive analysis of the crystallisation behaviour of palm oil was performed using low-resolution magnetic pulsed nuclear resonance, differential scanning calorimetry, polarised light microscopy and X-ray diffraction. The aim of this study was to characterise the changes induced in the crystallisation of palm oil by the addition of two different levels of tripalmitin and two different types of monoacylglycerols. The addition of monoacylglycerols led to the formation of a large number of crystallisation nuclei without changing the final solids content, accelerating the process of crystal formation, leading to the formation of smaller crystals than those found in the refined palm oil. Higher levels of tripalmitin produced crystals with larger dimensions, reducing the induction period and resulted in a higher level of solids at the end of the crystallisation period. The addition of monoacylglycerols and tripalmitin induced the formation of a polymorphic beta-form. (C) 2010 Elsevier Ltd. All rights reserved.

Influence of chemical interesterification on thermal behavior, microstructure, polymorphism and crystallization properties of canola oil and fully hydrogenated cottonseed oil blends

This work evaluated chemical interesterification of canola oil (CaO) and fully hydrogenated cottonseed oil (FHCSO) blends, with 20%, 25%, 30%, 35% and 40%(w/w) FHCSO content. Interesterification produced reduction of trisaturated and increase in monounsaturated and diunsaturated triacylglycerols contents, which caused important changes in temperatures and enthalpies associated with the crystallization and melting thermograms. It was verified reduction in medium crystal diameter in all blends, in addition crystal morphology modification. Crystallization kinetics revealed that crystal formation induction period and maximum solid fat content were altered according to FHCSO content in original blends and as a result of random rearrangement. Changes in Avrami constant (k) and exponent (n) indicated, respectively, that interesterification decreased crystallization rates and altered crystalline morphology. However, X-ray diffraction analyses showed randomization did not change the original crystalline polymorphism. The original and interesterified blends had significant predominance of beta` polymorph, which is interesting for several food applications. (C) 2009 Elsevier Ltd. All rights reserved.

Thermal Behavior, Microstructure, Polymorphism, and Crystallization Properties of Zero Trans Fats from Soybean Oil and Fully Hydrogenated Soybean Oil

Blends of soybean oil (SO) and fully hydrogenated soybean oil (FHSBO), with 10, 20, 30, 40, and 50% (w/w) FHSBO content were interesterified under the following conditions: 20 min reaction time, 0.4% sodium methoxide catalyst, and 500 rpm stirring speed, at 100 A degrees C. The original and interesterified blends were examined for triacylglycerol composition, thermal behavior, microstructure, crystallization kinetics, and polymorphism. Interesterification produced substantial rearrangement of the triacylglycerol species in all the blends, reduction of trisaturated triacylglycerol content and increase in monounsaturated-disaturated and diunsaturated-monosaturated triacylglycerols. Evaluation of thermal behavior parameters showed linear relations with FHSBO content in the original blends. Blend melting and crystallization thermograms were significantly modified by the randomization. Interesterification caused significant reductions in maximum crystal diameter in all blends, in addition to modifying crystal morphology. Characterization of crystallization kinetics revealed that crystal formation induction period (tau (SFC)) and maximum solid fat content (SFC(max)) were altered according to FHSBO content in the original blends and as a result of the random rearrangement. Changes in Avrami constant (k) and exponent (n) indicated, respectively, that-as compared with the original blends-interesterification decreased crystallization velocities and modified crystallization processes, altering crystalline morphology and nucleation mechanism. X-ray diffraction analyses revealed that interesterification altered crystalline polymorphism. The interesterified blends showed a predominance of the beta` polymorph, which is of more interest for food applications.

In situ gelling hexagonal phases for sustained release of an anti-addiction drug

In this study, fluid precursor formulations for subcutaneous injection and in situ formation of hexagonal phase gels upon water absorption were developed as a strategy to sustain the release of naltrexone, a drug used for treatment of drug addiction. Precursor formulations were obtained by combining BRIJ 97 with propylene glycol (PG, 5-70%, w/w). To study the phase behavior of these formulations, water was added at 10-90% (w/w), and the resulting systems were characterized by polarized light microscopy. Two precursor formulations containing BRIJ:PG at 95:5 (w/w, referred to as BRIJ-95) and at 80:20 (w/w, referred to as BRIJ-80) were chosen. Naltrexone was dissolved at 1% or suspended at 5% (w/w). Precursor formulations were transformed into hexagonal phases when water content exceeded 20%. Water uptake followed second-order kinetics, and after 2-4 h all precursor formulations were transformed into hexagonal phases. Drug release was prolonged by the precursor formulations (compared to a drug solution in PBS), and followed pseudo-first order kinetics regardless of naltrexone concentration. The release from BRIJ-80 was significantly higher than that from BRIJ-95 after 48 h. The relative safety of the precursor formulations was assessed in cultured fibroblasts. Even though BRIJ-95 was more cytotoxic than BRIJ-80, both precursor formulations were significantly less cytotoxic than sodium lauryl sulfate (considered moderate-to-severe irritant) at the same concentration (up to 50 mu g/mL). These results suggest the potential of BRIJ-based precursor formulations for sustained naltrexone release. (C) 2011 Elsevier By. All rights reserved.

Sustained release carriers used to delivery bone morphogenetic proteins in the bone healing process

Bone morphogenetic proteins (BMPs) are multi-functional growth factors belonging to the transforming growth factor beta superfamily, especially BMP-2, induce bone formation in vivo, and clinical application in repair of bone fractures and defects is expected. However, appropriate systems to delivery BMPs for practical use need to be developed with the objective to heal cartilage and bone-related diseases in medical, dental and veterinary practice. Thus, the aim of this article was to present an overview of the principals carriers used to delivery BMPs and alternative delivery systems for these proteins.

Analysis of the Phase Changes During Evaporation of Emulsions with Different Oil Phases

Emulsions surfer alterations in their microstructure after applied on the skin, because of the interaction with skin constituents and mainly by the evaporation of volatile components. These alterations are not even considered by cosmetic formulators, but they are extremely important because they can act on formulation stability, on delivery and on permeation of actives and also on the ability to build the occlusive film, responsible for skin`s moisturization. This research studied the phase changing during evaporation of emulsions made with three different oil phase: mineral oil, avocado oil, and isocethyl/stearoil stearate, as a function of the decrease on water ratio, using phase diagrams and evaporation test. It was observed the formation of liquid crystalline phases and their transition along the evaporation path for emulsions with the three different oil phases. It was also observed that these transitions occurred in different water ratios.

Investigation of the role of cadmium sulfide in the surface passivation of lead sulfide quantum dots

Surface passivation of PbS nanocrystals (NC), resulting in strong photoluminescence, can be achieved by the introduction of CdS precursors. The role of CdS in the surface passivation of PbS NCs is uncertain, as the crystalline structure of CdS and PbS are different, which should impede effective epitaxial overgrowth. Absorption spectroscopy is used to show that the CdS precursors strongly interact with the PbS NC surface. Electron microscopy reveals that the introduction of CdS precursors results in an increased particle size, consistent with overcoating. However, we also find the process to be highly non-uniform. Nevertheless, evidence for epitaxial growth is found, suggesting that effective surface passivation may be possible.

Magma Flow Instabilities in a Volcanic Conduit: Implications for Long-Period Seismicity

Silicic volcanic eruptions are typically accompanied by repetitive Long-Period (LP) seismicity that originates from a small region of the upper conduit. These signals have the capability to advance eruption prediction, since they commonly precede a change in the eruption vigour. Shear bands forming along the conduit wall, where the shear stresses are highest, have been linked to providing the seismic trigger. However, existing computational models are unable to generate shear bands at the depths where the LP signals originate using simple magma strength models. Presented here is a model in which the magma strength is determined from a constitutive relationship dependent upon crystallinity and pressure. This results in a depth-dependent magma strength, analogous to planetary lithospheres. Hence, in shallow highly-crystalline regions a macroscopically discontinuous brittle type of deformation will prevail, whilst in deeper crystal-poor regions there will be a macroscopically continuous plastic deformation mechanism. This will result in a depth where the brittle-ductile transition occurs, and here shear bands disconnected from the free-surface may develop. We utilize the Finite Element Method and use axi-symmetric coordinates to model magma flow as a viscoplastic material, simulating quasi-static shear bands along the walls of a volcanic conduit. Model results constrained to the Soufrière Hills Volcano, Montserrat, show the generation of two types of shear bands: upper-conduit shear bands that form between the free-surface to a few 100 metres below it and discrete shear bands that form at the depths where LP seismicity is measured to occur corresponding to the brittle-ductile transition and the plastic shear region. It is beyond the limitation of the model to simulate a seismic event, although the modelled viscosity within the discrete shear bands suggests a failure and healing cycle time that supports the observed LP seismicity repeat times. However, due to the paucity of data and large parameter space available these results can only be considered to be qualitative rather than quantitative at this stage.

A relative gradient theory for layered materials

It is possible to remedy certain difficulties with the description of short wave length phenomena and interfacial slip in standard models of a laminated material by considering the bending stiffness of the layers. If the couple or moment stresses are assumed to be proportional to the relative deformation gradient, then the bending effect disappears for vanishing interface slip, and the model correctly reduces to an isotropic standard continuum. In earlier Cosserat-type models this was not the case. Laminated materials of the kind considered here occur naturally as layered rock, or at a different scale, in synthetic layered materials and composites. Similarities to the situation in regular dislocation structures with couple stresses, also make these ideas relevant to single slip in crystalline materials. Application of the theory to a one-dimensional model for layered beams demonstrates agreement with exact results at the extremes of zero and infinite interface stiffness. Moreover, comparison with finite element calculations confirm the accuracy of the prediction for intermediate interfacial stiffness.

Novel silica gel supported TiO2 photocatalyst synthesized by CVD method

TiO2 in anatase crystal phase is a very effective catalyst in the photocatalytic oxidation of organic compounds in water. To improve the recovery rate of TiO2 photocatalysts, which in most cases are in fine powder form, the chemical vapor deposition (CVD) method was used to load TiO2 onto a bigger particle support, silica gel. The amount of titania coating was found to depend strongly on the synthesis parameters of carrier gas flow rate and coating time. XPS and nitrogen ads/desorption results showed that most of the TiO2 particles generated from CVD were distributed on the external surface of the support and the coating was stable. The photocatalytic activities of TiO2/silica gel with different amounts of titania were evaluated for the oxidation of phenol aqueous solution and compared with that of Degussa P25. The optimum titania loading rate was found around 6 wt % of the TiO2 bulk concentration. Although the activity of the best TiO2/silica gel sample was still lower than that of P25, the synthesized TiO2/silica gel catalyst can be easily separated from the treated water and was found to maintain its TiO2 content and catalytic activity.

Aluminophosphate-based mesoporous molecular sieves: synthesis and characterization of TAPOs

Mesoporous Ti-substituted aluminophosphates (AlPOs) with a hexagonal, cubic and lamellar pore structure, characteristic of MCM-41, MCM-48. and MCM-50, respectively, were synthesized. The stability of these mesophases upon template removal was studied. The pore structures, surface properties, and local atom environments of Al, P, and Ti of the hexagonal and cubic Ti-containing mesoporous products were extensively characterized using X-ray diffraction, magic angle spinning nuclear magnetic resonance, AAS, XPS, ultraviolet-visible, and adsorption of nitrogen and water vapor techniques while the lamellar mesophase was not further characterized due to its very poor thermal stability. Ti-containing mesoporous AlPO materials show a reasonable thermal stability upon template removal, a hydrophilic surface property, and high porosity showing application potentials in catalytic oxidation of hydrocarbons. (C) 2001 Elsevier Science B,V. All rights reserved.

Visible and near-infrared luminescent Eu(3+) or Er(3+) doped laponite-derived xerogels and thick films: Structural and spectroscopic properties

Laponite-derived materials represent promising materials for optical applications. In this work, Eu(3+)- or Er(3+)-doped laponite xerogels and films were prepared from colloidal dispersion. Homogeneous, crack-free and transparent single layers were deposited on soda-lime substrates with a thickness of 10 mu m. Structural and spectroscopic properties were analyzed by thermal analyses, X-ray diffractometry, transmission electron microscopy, infrared spectroscopy, and luminescence spectroscopy. The addition of a rare earth ion to the laponite does not promote any changes in thermal stability or phase transition. Laponite clay was identified after annealing up to 500 degrees C, with a decrease in basal spacing when the annealing temperature is changed from 100 degrees C to 500 degrees C. Enstatite polymorphs and amorphous silicate phases were observed after heat treatment at 700 degrees C and 900 degrees C. Stationary and time-dependent luminescence spectra in the visible region for Eu(3+), and (5)D(0) lifetime are discussed in terms of thermal treatment and structural evolution. In the layered host, the Eu(3+) ions are distributed in many different local environments. However, Eu(3+) ions were found to occupy at least two symmetry sites, and the ions are preferentially incorporated into the crystalline enstatite for the materials annealed at 700 degrees C and 900 degrees C. A (5)D(0) lifetime of 1.3 ms and 3.1 ms was obtained for Eu(3+) ions in an amorphous silicate and crystalline MgSiO(3) local environment, respectively. Strong Er(3+) emission at the 1550 nm region was observed for the materials annealed at 900 degrees C, with a bandwidth of 44 nm. (C) 2008 Elsevier B.V. All rights reserved.

Application of Ti/RuO(2)-Ta(2)O(5) electrodes in the electrooxidation of ethanol and derivants: Reactivity versus electrocatalytic efficiency

The influence of the preparation method on the performance of RuO(2)-Ta(2)O(5) electrodes was evaluated toward the ethanol oxidation reaction (EOR). Freshly prepared RuO(2)-Ta(2)O(5) thin films containing between 30 and 80 at.% Ru were prepared by two different methods: the modified Pechini-Adams method (DPP) and standard thermal decomposition (STD). Electrochemical investigation of the electrode containing RuO(2)-Ta(2)O(5) thin films was conducted as a function of electrode composition in a 0.5-mol dm(-3) H(2)SO(4) solution, in the presence and absence of ethanol and its derivants (acetaldehyde and acetic acid). At a low ethanol concentration (5 mmol dm(-3)), ethanol oxidation leads to high yields of acetic acid and CO(2). On the other hand, an increase in ethanol concentration (15-1000 mmol dm(-3)) favors acetaldehyde formation, so acetic acid and CO(2) production is hindered, in this case. Electrodes prepared by DPP provide higher current efficiency than STD electrodes for all the investigated ethanol concentrations. This may be explained by the increase in electrode area obtained with the DPP preparation method compared with STD. (c) 2008 Elsevier Ltd. All rights reserved.

Morphological and electrochemical investigation of RuO(2)-Ta(2)O(5) oxide films prepared by the Pechini-Adams method

Preparation methods can profoundly affect the structural and electrochemical properties of electrocatalytic coatings. In this investigation, RuO(2)-Ta(2)O(5) thin films containing between 10 and 90 at.% Ru were prepared by the Pechini-Adams method. These coatings were electrochemically and physically characterized by cyclic voltammetry, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The composition and morphology of the oxide were investigated before and after accelerated life tests (ALT) by EDX and SEM. SEM results indicate typical mud-flat-cracking morphology for the majority of the films. High resolution SEMs reveal that pure oxide phases exhibit nanoporosity while binary compositions display a very compact structure. EDX analyses reveal considerable amounts of Ru in the coating even after total deactivation. XRD indicated a rutile-type structure for RuO(2) and orthorhombic structure for Ta(2)O(5). XPS data demonstrate that the binding energy of Ta is affected by Ru addition in the thin films, but the binding energy of Ru is not likewise influenced by Ta. The stability of the electrodes was evaluated by ALT performed at 750 mA cm(-2) in 80 degrees C 0.5 mol dm(-3) H(2)SO(4). The performance of electrodes prepared by the Pechini-Adams method is 100% better than that of electrodes prepared by standard thermal decomposition.