Impact of surface deposition of lactoferrin on physical and chemical stability of omega-3 rich lipid droplets stabilised by caseinate

There is considerable interest in developing delivery systems to encapsulate and protect chemically labile lipophilic food components, such as omega-3 rich oils. In this study, multilayer emulsion-based delivery systems were prepared consisting of omega-3 rich oil droplets coated by either caseinate (Cas) or lactoferrin–caseinate (LF–Cas). Surface deposition of LF onto Cas-coated oil droplets was confirmed by ζ-potential measurements. Emulsions containing lactoferrin and caseinate had better physical stability to pH changes and salt addition (pH 3–7, 0–50 mM CaCl₂ at pH 7) than those containing only caseinate (pH 5–7, 0–2 mM CaCl₂ at pH 7). The addition of LF also retarded the formation of lipid oxidation markers (hydroperoxides and thiobarbituric acid reactive substances) in the emulsions. The ability of LF to enhance both the physical and chemical stability of protein-stabilised emulsions is useful for the fabrication of delivery systems designed for utilisation within the drug and food industries.     

Impact of cosolvents on formation and properties of biopolymer nanoparticles formed by heat treatment of β-lactoglobulin–Pectin complexes

The purpose of this study was to determine the influence of neutral cosolvents on the formation and properties of biopolymer nanoparticles formed by thermal treatment of protein–polysaccharide electrostatic complexes. Biopolymer particles were formed by heating (85 °C, 20 min) an aqueous solution containing a globular protein (β-lactoglobulin) and an anionic polysaccharide (beet pectin) above the thermal denaturation temperature (T_m) of the protein under pH conditions where the biopolymers formed electrostatic complexes (pH 5). The impact of two neutral cosolvents (glycerol and sorbitol) on the self-association of β-lactoglobulin and on the formation of β-lactoglobulin–pectin complexes was examined as a function of solution pH (3–7) and temperature (30–95 °C). Glycerol had little impact on the pH-induced self-association or aggregation of the biopolymers, but it did increase the thermal aggregation temperature (T_a) of the protein–polysaccharide complexes, which was attributed to its ability to increase aqueous phase viscosity. Sorbitol decreased the pH where insoluble protein–polysaccharide complexes were formed, and greatly increased their T_a, which was attributed to its ability to increase T_m, alter biopolymer–biopolymer interactions, and increase aqueous phase viscosity. This study shows that neutral cosolvents can be used to modulate the properties of biopolymer nanoparticles prepared by thermal treatment of protein–polysaccharide electrostatic complexes.     

Disentangling the indirect links between socioeconomic status and health: The dynamic roles of work stressors and personal control.

Prior research has documented an indirect link between socioeconomic status (SES) and health, and the goal in this study was to help unravel this phenomenon from a dynamic perspective. The authors hypothesized that SES would be positively related to feelings of personal control and negatively related to perceived work stressors. Drawing on dynamic conceptualizations of these psychosocial factors, they suggest that these psychosocial factors relate to one another over time. Individuals who have higher levels of personal control experience increasingly fewer work stressors over time than do those with lower levels of personal control, and those who experience greater work stressors increasingly perceive less personal control over time than do those with fewer work stressors. Finally, the authors argue that trajectories of personal control and work stressors are associated with the accumulation of health problems over the same period. Their model was tested with 3-wave data (over 4 years) from a nationally representative sample of Canadian employees (N = 3,419). Latent curve modeling provides support for the proposed dynamic model. Conceptual and practical implications are drawn, and suggestions for future research are outlined. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Closed-loop feedback control of product properties in flexible metal forming processes with mobile tools

The accuracy of flexible forming processes with mobile tools is generally insufficient for industrial needs. Modern stereovision cameras should allow geometric feedback to improve accuracy, but to date it has been assumed that on-line control is in practice impossible because non-linear process models are too slow. This paper demonstrates for the first time that an appropriate process model can be formed from a set of spatial impulse responses found by linearisation around a pre-planned tool path. This allows on-line feedback control of part geometry. A general formulation is presented, and is evaluated through application to an axisymmetric incremental sheet forming process.     

New trends in bioactive scaffolds: The importance of nanostructure

There are many criteria for an ideal scaffold that will stimulate the body's repair mechanisms to regenerate diseased or damaged bone to its original healthy state. These include having a pore network large and open enough for cells and blood vessels to penetrate and the ability to bond to bone. Sol–gel derived bioactive glasses have a nanoporosity that can control degradation rate. They can be foamed to produce scaffolds that mimic cancellous bone macrostructure. Bioactive glass foams with optimised nanoporosity are strong in compression; however, they have low toughness and pore strength when loaded in tension. Therefore an ideal scaffold would have all the properties of the glasses with enhanced toughness. This can only be achieved by creating new nanoscale composites. Resorbable polymers must interact with the silica based inorganic network at the nanoscale to maintain bioactivity and controlled resorption. This is a complex problem but may be the future of scaffold development.     

The mechanics of incremental sheet forming

The deformation mechanism of incremental sheet forming (ISF) is examined experimentally through forming specially prepared copper sheets. Strain distributions through the thickness of the sheets are measured for two configurations of ISF: two-point incremental forming (TPIF) and single-point incremental forming (SPIF), and a comparison is made to pressing. The measurements show that the deformation mechanisms of both SPIF and TPIF are stretching and shear in the plane perpendicular to the tool direction, with shear in the plane parallel to the tool direction. Strain components increase on successive laps, and the most significant component of strain is shear parallel to the tool direction. Increasing stretching and shear perpendicular to the tool direction account for differences between the sine law prediction and measured wall thickness for both SPIF and TPIF. The observed mechanisms of SPIF and TPIF differ from a mechanism of pure shear that has previously been assumed.     

Characterization of a composite structure obtained by RFI using HexFIT semi-products

The HexFIT^™ is a semi-product used for large structures manufactured by the RFI process. In this work, large plate made of a quasi-isotropic lay-up is considered. The presented study aims at mechanically characterizing and identifying the process impact for such a structure. NDT (US & IR) are first used to highlight material heterogeneities and thickness variations. This approach helps us to define a sampling protocol in order to select tensile coupons taking into account thickness and width. Multi-instrumented tensile tests (strain field measurement, gauges and extensometer) are undertaken on specimens showing different widths, but almost same thicknesses. Comparison between the different strain measurements leads to qualify specific sensors for future characterizations.     

An in vitro study of electrically active hydroxyapatite-barium titanate ceramics using Saos-2 cells

Electrically active ceramics are of interest as bone graft substitute materials. This study investigated the ferroelectric properties of hydroxyapatite-barium titanate (HABT) composites and the behaviour of osteoblast-like cells seeded on their surfaces. A piezoelectric coefficient (d₃₃) of 57.8 pCN⁻¹ was observed in HABT discs prepared for cell culture. The attachment, proliferation, viability, morphology and metabolic activity of cells cultured on unpoled HABT were comparable to those observed on commercially available hydroxyapatite at all time points. No indication of the cytotoxicity of HABT was detected. At one day after seeding, cell attachment was modified on both the positive and negative surfaces of poled HABT. After longer incubations, all parameters observed were comparable on poled and unpoled ceramics. The results indicate that HABT ceramics are biocompatible in the short term in vitro and that further investigation of cell responses to these materials under mechanical load and at longer incubation times is warranted.     

Fabrication of Millimeter-Wave Electromagnetic Bandgap Crystals Using Microwave Dielectric Powders

Electromagnetic bandgap (EBG) structures active in the 90–110 GHz region widely used by security imaging radar were created using different ceramics by a rapid prototyping method informed by finite difference time domain modeling. This solid free-forming method uses a high volatility solvent-based ceramic paste extruded through fine nozzles allowing ceramic powders to be assembled on a multiaxis building platform avoiding machining, etching, or the alignment of loose rods and created to designs downloaded directly from a computer file. Lattices were made from two high dielectric constant ceramics: La(Mg_0.5, Ti_0.5)O₃ and (Zr_0.8, Sn_0.2)TiO₄ and compared with those of Al₂O₃ demonstrating three EBG structures with different dimensions and dielectric constants but with the same bandgap. The effects of manufacturing tolerances on bandgap frequency are investigated by simulation.     

Measurement of the impedance change of impregnated activated carbon during exposure to SO2 vapors at ambient temperatures

The impedance of impregnated carbon is measured in real time during exposure to SO₂ vapors at ambient temperatures using a plug flow reactor and an impedance monitor. Impedance measurements are accomplished using a dual parallel plate mesh electrode configuration that measures the electrical conductivity of the carbon bed using an impedance analyzer operating at 10 Hz. It is observed for all impregnated carbon samples undergoing SO₂ exposure the carbon impedance undergoes an initial increase followed by a longer lasting characteristic decrease. The rate of the initial impedance increase appears to be proportional to the SO₂ partial pressure, while the impedance drops more quickly with increasing relative humidity and additive concentration. From these findings, along with XPS measurements to identify the chemical composition of the carbon bed, it is postulated that the SO₂ interaction with impregnated activated carbon is governed by an initial physical adsorption of SO₂ vapors onto the activated carbon followed by a catalytic oxidation of SO₂ to SO₃ and eventually a conductive sulfate-containing acid like H₂SO₄.