Properties of filmogenic solutions of gliadin crosslinked with 1-(3-dimethyl aminopropyl)-3-ethylcarbodiimidehydrochloride/N-hydroxysuccinimide and cysteine

In this study gliadin solutions were crosslinked with 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS) and cysteine. The filmogenic solutions were studied through rheological, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and FTIR analysis. Gliadin modified by EDC/NHS showed lower viscosity values when compared with the gliadin/cysteine system and the non-modified gliadin system. Determination of amino groups in gliadin modified by EDC/NHS was carried out through the trinitrobenzenesulfonic acid (TNBS) method. The cast films were evaluated by FTIR analysis in order to detect structural changes in the secondary structure of protein. SDS-PAGE showed the formation of higher protein aggregates, indicating that cysteine promotes gliadin polymerization through covalent bonds (disulfide bonds). The TNBS analysis showed that non-chemically modified gliadin had higher amounts of ε-amino groups when compared with gliadin treated with EDC/NHS; however, both systems revealed similar amounts of amino groups for the whole range of glycerol content. The FTIR spectra for the films showed that the two crosslinking agents act by different mechanisms, promoting changes in the secondary structure of gliadin.     

Carbon nanotube dispersion in aluminum matrix composites—Quantification and influence on strength

Carbon nanotube (CNT) incorporation in metal matrix composites is hampered by the development of attractive van der Waals forces, which lead to the formation of CNT agglomerates. Therefore, a detailed quantification and characterization of CNT agglomerates and consequently CNT dispersion can enlighten their influence in composites strength. This work presents a comprehensive study, quantifying agglomerates by size, for three different composites (2, 4, and 6 CNT vol%), made with an aluminum-silicon matrix by a powder metallurgy route. From the obtained experimental data, an empirical model that attempts to predict the tensile strength of these composites from CNT agglomerates analysis is presented.     

Mechanisms governing the tensile,fatigue, and wear behavior of carbon nanotube reinforced aluminum alloy

This work is concerned with understanding the influence of reinforcement mechanisms of carbon nanotubes (CNTs) on mechanical, wear, and fatigue tests on an Aluminium-Silicon (AlSi) alloy. The reinforcement mechanism is presented through the observation of fracture morphology of the different tests. Results of mechanical properties, fatigue life performance, and wear loss is presented and discussed. It is shown that the CNTs reinforcement effect is active simultaneously in all previous properties and the reinforcement physical mechanism seems to be essentially due to a reinforcement effect of the interface that seems to be similar in all mentioned mechanical solicitations.     

Optimal tracking under decoupling constraints

In this paper, a servomechanism problem is considered in which a stabilizing controller is to be chosen as the solution of a H 2-optimization problem with asymptotic tracking and (exact or approximate) decoupling constraints. The cost functional is made-up of terms which penalize the tracking error and control effort associated with a class of persistent reference signals. To solve the optimization problem with asymptotic tracking and exact decoupling constraints, an explicit parametrization is presented of all stabilizing controllers which satisfy these constraints. On the basis of this parametrization the problem in question is recast as an unconstrained H ₂ problem and conditions on problem data are then stated under which there exists a unique solution. To handle the case of asymptotic tracking and approximate decoupling constraints, a parametrization of all stabilizing controllers which achieve asymptotic tracking is used to eliminate the tracking constraint; this leads to an H ₂ optimization problem with several non-definite H ₂ constraints. Approximate solutions to such a problem are obtained by means of a sequence of H ₂ problems with a single non-definite H ₂ constraint which, in turn, are solved by line search and spectral factorization. A numerical example is presented to illustrate the effect of the exact and approximate decoupling constraints on the attained optimal cost value and time responses.     

Valorization of Beef Tallow by Lipase-Catalyzed Interesterification with High Oleic Sunflower Oil

Although beef tallow (BT) has been considered a hard low-trans fat convenient to be used in several bakery applications, it has some undesirable characteristics like fatty acid composition, crystallization behavior, graininess formation and poor plastic range. This work studied the modification of BT by blending at different percentages with high oleic sunflower oil (HOSFO) followed by the enzyme-catalyzed interesterification of the blends. The reduction in the solid fat content achieved by the simple blending was enhanced by the interesterification process, as a result of the increase in the concentration of the diunsaturated monosaturated type triacylglycerols. Interesterification strongly impacted too on the crystallization behavior of the blends, since products showed more homogeneous and regular crystals than the starting mixture. Results show that lipase catalyzed interesterification of BT with HOSFO offers a useful tool for the design of fats with adjustable physicochemical properties, improved with respect to that of the starting fats.     

Calcium and Vitamin D in the Regulation of Energy Balance: Where Do We Stand?

There is a pandemic of obesity and associated chronic diseases. Dietary calcium and vitamin D have many extra-skeletal roles in human health. In this review we have summarized the current understanding of their influence on human energy balance by examining the epidemiological, clinical, animal, cellular and molecular evidence. We opine that while calcium and vitamin D are functional nutrients in the battle against obesity, there is a need for prospective human trials to tilt the balance of evidence in favour of these nutrients.