Anticoagulant, Antioxidant and Antitumor Activities of Heterofucans from the Seaweed Dictyopteris delicatula

In the present study, six families of sulfated polysaccharides were obtained from seaweed Dictyopteris delicatula by proteolytic digestion, followed by acetone fractionation and molecular sieving on Sephadex G-100. Chemical analyses demonstrated that all polysaccharides contain heterofucans composed mainly of fucose, xylose, glucose, galactose, uronic acid, and sulfate. The fucans F0.5v and F0.7v at 1.0 mg/mL showed high ferric chelating activity (～45%), whereas fucans F1.3v (0.5 mg/mL) showed considerable reducing power, about 53.2% of the activity of vitamin C. The fucan F1.5v presented the most prominent anticoagulant activity. The best antiproliferative activity was found with fucans F1.3v and F0.7v. However, F1.3v activity was much higher than F0.7v inhibiting almost 100% of HeLa cell proliferation. These fucans have been selected for further studies on structural characterization as well as in vivo experiments, which are already in progress.     

Efficiency and stability of transition metal electrocatalysts for the hydrogen evolution reaction using ionic liquids as electrolytes

Different electrodes (nickel, molybdenum, and iron alloys containing chromium, manganese, and nickel) were tested as cathodes for the hydrogen evolution reaction (HER) using 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMI.BF₄) ionic liquid (IL) as the electrolyte. HERs were conducted at room temperature, at a cathodic potential of −1.7 V (PtQRE) using 10 vol.% aqueous BMI.BF₄ solutions. Reactions performed in a thermostated Hoffman cell gave current densities between 14.6 and 77.5 mA cm⁻² and efficiencies in the range 97.0–99.2%. Mo electrocatalysts in IL have been shown to be better than Pt, contrary to the classic behavior observed in an aqueous KOH medium. The electrochemical properties of molybdenum, as well as its resistance to corrosion (studied by Tafel plots and observed using SEM) indicate the potential use of this material as a cathode in an IL medium, which can lead to many attractive technological applications.     

A simple analytical model to study and control azimuthal instabilities in annular combustion chambers

This study describes a simple analytical method to compute the azimuthal modes appearing in annular combustion chambers and help analyzing experimental, acoustic and large eddy simulation (LES) data obtained in these combustion chambers. It is based on a one-dimensional zero Mach number formulation where N burners are connected to a single annular chamber. A manipulation of the corresponding acoustic equations in this configuration leads to a simple dispersion relation which can be solved by hand when the interaction indices of the flame transfer function are small and numerically when they are not. This simple tool is applied to multiple cases: (1) a single burner connected to an annular chamber (N = 1), (2) two burners connected to the chamber (N = 2), and (3) four burners (N = 4). In this case, the tool also allows to study passive control methods where two different types of burners are mixed to control the azimuthal mode. Finally, a complete helicopter chamber (N = 15) is studied. For all cases, the analytical results are compared to the predictions of a full three-dimensional Helmholtz solver and a very good agreement is found. These results show that building very simple analytical tools to study azimuthal modes in annular chambers is an interesting path to control them.     

Optimization of a Wall Material Formulation to Microencapsulate a Grape Seed Extract Using a Mixture Design of Experiments

The microencapsulation by spray drying of a commercial grape seed extract (GSE) using maltodextrin (MD), mesquite gum (MG), and zein (Z) as wall materials was investigated. A mixture design of experiments (MDOE) with the three wall material components was used to find optimal wall material formulations. The parameters used to evaluate the microcapsules obtained were encapsulation efficiency (EE), encapsulation productivity (EP), release of the core material in water (RE Water), hygroscopicity (MH), and degree of caking (CD). Four optimal formulations were then selected and evaluated including antioxidant activity (AA), release of the core material at pH 1, 4, 7, and 10, and in simulated gastric (GF) and intestinal fluid (IF), morphology and glass transition temperature (Tg). Microcapsules had a smooth surface with sizes ranging from 4 to 16 μm, a Tg of 160?±?1 °C, and an AA of 1.90?±?0.05 mmoles Trolox/g. The two formulations with the most optimal results were T3 (44 % MG-56 % Z) and T4 (34 % MD-66 % Z), with an EE of 85 % and 82 % and an EP of 98 % and 99 %, respectively. The release was between 50 % to 52 % for T3 and 52 % to 55 % for T4 at the different pHs. The RE in GF and IF were 70 % and 63 %, respectively, for T3, and 71 % and 63 % for T4; most of the release happened during the first hour. Both formulations protected the GSE from thermal degradation at temperatures up to 180 °C.     

Effect of the curing régime on compressive strength

In a previous issue the Instituto Eduardo Torroja in Spain described the development of lightweight panels made from ordinary Portland cement and rice husk ash (RHA). This paper discusses the crucial effect of the curing régime on compressive strength with temperatures maintained at 30C and relative humidity at 80 percent.     

Multi-objective Optimization Models for Distributing Biosolids to Reuse Fields: A Case Study for the Blue Plains Wastewater Treatment Plant

This paper presents multi-objective optimization models that simultaneously minimize biosolids odors as well as wastewater treatment and biosolids distribution costs and can be proactively used by biosolids managers at advanced wastewater treatment plants. The computational aspects of these models are daunting, typically involving over 200,000 constraints and about 145,000 variables and are thus difficult to solve. Also, some of the mathematical terms involve bilinear, nonconvex pieces which need to be approximated. This paper presents both a numerical approximation scheme to linearize these nonconvex terms using Schur’s decomposition and SOS2 variables as well as a Dantzig–Wolfe decomposition method to improve the computational times. The computational results as well as a sensitivity analysis are performed using data from the Blue Plains advanced wastewater treatment plant in Washington, DC.     

A residual-based a posteriori error estimator for a fully-mixed formulation of the Stokes–Darcy coupled problem

In this paper we develop an a posteriori error analysis of a new fully mixed finite element method for the coupling of fluid flow with porous media flow in 2D. Flows are governed by the Stokes and Darcy equations, respectively, and the corresponding transmission conditions are given by mass conservation, balance of normal forces, and the Beavers–Joseph–Saffman law. We consider dual-mixed formulations in both media, which yields the pseudostress and the velocity in the fluid, together with the velocity and the pressure in the porous medium, and the traces of the porous media pressure and the fluid velocity on the interface, as the resulting unknowns. The set of feasible finite element subspaces includes Raviart–Thomas elements of lowest order and piecewise constants for the velocities and pressures, respectively, in both domains, together with continuous piecewise linear elements for the traces. We derive a reliable and efficient residual-based a posteriori error estimator for the coupled problem. The proof of reliability makes use of the global inf–sup condition, Helmholtz decompositions in both media, and local approximation properties of the Clément interpolant and Raviart–Thomas operator. On the other hand, inverse inequalities, the localization technique based on element-bubble and edge-bubble functions, and known results from previous works, are the main tools for proving the efficiency of the estimator. Finally, some numerical results confirming the theoretical properties of this estimator, and illustrating the capability of the corresponding adaptive algorithm to localize the singularities of the solution, are reported.     

Long-term fairness with bounded worst-case losses

How does one repeatedly choose actions so as to be fairest to the multiple beneficiaries of those actions? We examine approaches to discovering sequences of actions for which the worst-off beneficiaries are treated maximally well, then secondarily the second-worst-off, and so on. We formulate the problem for the situation where the sequence of action choices continues forever; this problem may be reduced to a set of linear programs. We then extend the problem to situations where the game ends at some unknown finite time in the future. We demonstrate that an optimal solution is intractable, and present two good approximation algorithms.