Sharing Resources in a P2P Network with Artificial Ants

As networks are growing up, more and more information becomes available every day. Despite the presence of software enabling communications and content sharing, they are not always shared among people inside networks. We present here an architecture aimed at helping people to share information items and find collaborators inside an organization. It is part of our PIAF framework, an intelligent agent system used to develop recommender and personalization software. The main contribution of this paper is the introduction of principles of stigmergy and artificial ants to model data flows in a social network.      

A polynuclear coordination glutarate of lanthanum(III) with an uncommon cage feature

The title compound, tri­aqua­tris­(glutarato)­dilanthanum(III) dihydrate, {[La₂(C₅H₆O₄)₃(H₂O)₃]·2H₂O}_n, is the first re­ported glutarate coordination polymer of lanthanum(III) without a protonated ligand. The noteworthy features in the structure are, firstly, the unusual binuclear lanthanum cage formed by three bridging bonds through O atoms involved in different coordination modes and, secondly, the very rare `malonate' mode exhibited by a di­carboxyl­ate ligand with an alkyl chain of five C atoms. To our knowledge, this η⁷ chelation for the glutarate ligand has not been reported and was thought to be forbidden for steric reasons. The gauche–gauche conformation of the corresponding ligand favours cage formation, but trans geometries created along the ligating O atoms prevent cluster packing. The two independent La atoms are nine‐ and tenfold coordinated, leading to distorted one‐face‐sharing LaO₇(H₂O)₂ and LaO₉(H₂O) polyhedra, respectively. In the three‐dimensional framework, these asymmetric subunits are linked in a zigzag manner via one‐edge‐sharing LaO₉(H₂O) polyhedra and are connected by the carbon backbone chains of the ligands. The structure is very compact and, unlike many other reported di­carboxyl­ate lanthanides, connectivity between the two metal atoms and the three ligands yields a crystal packing with cavities accommodating two guest water mol­ecules but without an open framework.     

Ultra fast synthesis of zinc oxide nanostructures by microwaves

We describe a novel route for the synthesis of nanostructured zinc oxide powder using a modified kitchen microwave. A SiC-based composite showing a very strong absorption of microwaves was used as a microwave heater. Tests showed that high temperatures exceeding 1700 C can be reached in less than hundred second exposure of the composite material of microwaves. Zinc oxide nanopowder was obtained by evaporation and oxidation of metallic zinc in the ambient atmosphere of the microwave oven. Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) techniques revealed the prepared powder includes a wide variety of nanostructures including nanoparticles, nanosheets and tetrapods.     

Multifractal Formalism for Selfsimilar Functions Expanded in Singular Basis

Selfsimilar functions can be written as the superposition of similar structures, at different scales, generated by a function g. Their expressions look like wavelet decompositions. In the case where g is regular, the multifractal formalism has been proved for the corresponding selfsimilar function, for Hölder exponents smaller than the regularity of g. In this paper, we show, in the case where g is the Schauder function (or the Haar function or a spline-type wavelet), that for larger Hölder exponents, the singularities of g can disturb the Hölder exponents of the associated selfsimilar function, modify the shape of the spectrum of singularities, and finally affect the validity of the multifractal formalism.     

Designing a multi-scroll chaotic system by operating Logistic map with fractal process

Recently, chaotic systems have been widely investigated in several engineering applications. This paper presents a new chaotic system based on Julia’s fractal process, chaotic attractors and Logistic map in a complex set. Complex dynamic characteristics were analyzed, such as equilibrium points, bifurcation, Lyapunov exponents and chaotic behavior of the proposed chaotic system. As we know, one positive Lyapunov exponent proved the chaotic state. Numerical simulation shows a plethora of complex dynamic behaviors, which coexist with an antagonist form mixed of bifurcation and attractor. Then, we introduce an algorithm for image encryption based on chaotic system. The algorithm consists of two main stages: confusion and diffusion. Experimental results have proved that the proposed maps used are more complicated and they have a key space sufficiently large. The proposed image encryption algorithm is compared to other recent image encryption schemes by using different security analysis factors including differential attacks analysis, statistical tests, key space analysis, information entropy test and running time. The results demonstrated that the proposed image encryption scheme has better results in the level of security and speed.     

Investigation of ligand exchange reactions in aqueous uranyl carbonate complexes using computational approaches

Carbonate anion exchange reactions with water in the uranyl-carbonate and calcium-uranyl-carbonate aqueous systems have been investigated using computational methods. Classical molecular dynamics (MD) simulations with the umbrella sampling technique were employed to determine potentials of mean force for the exchange reactions of water and carbonate. The presence of calcium counter-ions is predicted to increase the stability of the uranyl-carbonate species in accordance with previous experimental observations. However, the free energy barrier to carbonate exchange with water is found to be comparable both in the presence and absence of calcium cations. Possible implications of these results for uranyl adsorption on mineral surfaces are discussed. Density functional theory (DFT) calculations were also used to confirm the trends observed in classical molecular dynamics simulations and to corroborate the validity of the potential parameters employed in the MD scheme.     

Synthesis of New Adamantylated Heterocycles

A new adamantyl heterocycle has been prepared by condensation between o-phenylenediamine and β-keto ester and also by rearrangement of adamantylated compound. The synthesised products have been characterised by ¹H-NMR, IR and mass spectrum.