Evaluation of antioxidant activities of the edible and medicinal Acacia albida organs related to phenolic compounds

This study compared phenolic contents and antioxidant activity in different organs of Acacia albida (leaves and bark) and focuses on identification of phenolic compounds of leaves by HPLC-DAD. The analysed organs exhibited differences in total polyphenol contents (100 and 59.5 mg GAE g^? 1 DW). Phenolic contents of leaves were two times higher than those in bark. Ethanolic extracts exhibited good antioxidant activities with IC₅₀ = 26 μg mL^? 1 for DPPH and EC₅₀ = 50 μg mL^? 1 for FRAP. Identification by HPLC-DAD revealed the presence of nine phenolic compounds known for their high antioxidant activity. The results suggested that this species can be used as source of natural antioxidants.     

Electroosmosis law via homogenization of electrolyte flow equations in porous media

By the homogenization approach we justify a two-scale model of ion transport in porous media for one-dimensional horizontal steady flows driven by a pressure gradient and an external horizontal electrical field. By up-scaling, the electroosmotic flow equations in horizontal nanoslits separated by thin solid layers are approximated by a homogenized system of macroscale equations in the form of the Poisson equation for induced vertical electrical field and Onsager's reciprocity relations between global fluxes (hydrodynamic and electric) and forces (horizontal pressure gradient and external electrical field). In addition, the two-scale approach provides macroscopic mobility coefficients in the Onsager relations.     

Optimization by isochronal analysis. II. Changes in mobile phase velocity and temperature, and in mobile phase composition and temperature

The theory of resolution optimization by isochronal analysis is further extended to the cases involving simultaneous changes in mobile phase velocity and column temperature, and in mobile phase composition and temperature. In each case, the resolution equation, when written in terms of isochronal conditions, shows that improvements can be obtained without sacrificing analysis time. Several subcases, which relate to the dependence of the selectivity factors on the changed parameters, are described. For each system, the contributions of the various parameters to the resolution are examined. The results of these discussions are plotted as resolution surfaces, on which lines of constant analysis time are indicated. The experimental routes that chromatographers must take in order to apply isochronal analysis are described.     

Interference-Aware QoS Guarantees in OFDM-Based Cognitive Radio Networks Based on Branch and Bound

Wireless Personal Communications - In the past decade, the OFDM access method has been widely used in different types of networks. Indeed; OFDM is the technology of choice for all major wireless...     

On the stochastic timed Pétri nets model and its application to the DQDB protocol

The goal of this paper is twofold : at first, to present the stochastic timed Pétri nets model by emphasizing its ability to express the main characteristics of real time distributed systems (parallelism, synchronization by message exchange, time attributes and in particular time constraints) and to allow both qualitative and quantitative analysis (concept of randomized states graph); second, to show a modeling methodology based on this model that allows a rigorous modeling of theDqdb protocol (Qa access, bwb mechanism role,Pa access influence). A new contribution to theQa mechanism has been done (1).     

Temperature, H2 loading and ultra violet irradiation effects in germanosilicate optical fibers: laser spectroscopy measurements

The effects of heat-treatment and ultraviolet (UV) light at 325 nm on virgin and hydrogen loaded germanosilicate optical fibers have been investigated by using laser spectroscopy technique. The luminescence band around 650 nm is sensitive to heat treatment. The hydrogen reloading of the hydrogen loaded fibers subsequent to heat treatment showed a new emission band around 570 nm. The irradiated fibers have an emission band around 383 nm which was not detected in hydrogen loaded fibers.     

Swelling Behaviour of Isotropic Poly(n-butyl acrylate) Networks in Isotropic and Anisotropic Solvents

Summary: The swelling properties of photochemically crosslinked poly(n-butyl acrylate) (PABu) networks in isotropic and anisotropic solvents were investigated experimentally. The purpose of this study was to examine the swelling kinetics of PABu networks in isotropic solvents and to compare the results obtained which those observed in the case of the low molecular weight liquid crystal 4-cyano-4′-n-pentyl-biphenyl known as 5CB. The phase diagrams were established in terms of composition and temperature for isotropic solvents, as toluene, acetone, cyclohexane, and methanol, and 5CB, using the plateau values corresponding to equilibrium states of swelling. The polymer networks were prepared via free radical polymerization/crosslinking processes by ultraviolet (UV) radiation of initial mixtures made up from a monomer, a crosslinker, and a photoinitiator. PABu networks with several crosslinking densities were formed using different quantities of difunctional monomer hexanedioldiacrylate (HDDA). Immersion of these networks in excess solvent allows measuring the solvent uptake by determination of the weight in isotropic solvents and diameter in an anisotropic solvent (5CB). Swelling data were rationalized by calculating weight and diameter ratios considering swollen to dry network states of the samples.     

A statistical trust system in wireless mesh networks

Most trust and reputation solutions in wireless mesh networks (WMNs) rely on the intrusion detection system (IDS) Watchdog. Nevertheless, Watchdog does not consider packet loss on wireless links and may generate false positives. Consequently, a node that suffers from packet loss on one of its links may be accused wrongly, by Watchdog, of misbehaving. To deal with this issue, we propose in this paper a novel trust system which considers packet loss of links. Our trust system is based on a statistical detection method (SDM) implemented on each node of the network. Firstly, the SDM, via CUSUM test, analyzes the behavior of the packets loss in order to detect a dropping attack. Secondly, the SDM, through the Kolmogorov-Smirnov test, compares the behavior of the total packets loss with that of the control packets in order to identify the attack type. Our system allows every WMN’s node to assign to each of its neighbors, a trust value which reflects its real behavior. We have validated the proposed SDM method via extensive simulations on ns2 and have compared our trust system with an existing solution. The results display that our SDM solution offers better performance.