Synthesis of a New Ditopic Ligand Possessing Linear and Cyclic Tetraaza Subunits

An easy‐to‐run route to a new ditopic ligand possessing linear and cyclic tetraaza subunits is described. In the first step, the reaction consists in the preparation of a triprotected cyclam bearing a 3‐bromopropyl pendant side chain. A subsequent reaction with a bisaminal protected linear tetraamine gives, after deprotection, the desired ditopic ligand.     

A Facile and General Synthesis of Phosphinylguanidines

Abstract

In order to synthesize new phosphorus guanidines 3, 5 as potential agrochemicals the reactivity of phosphorus cyanamides 1,4, was investigated towards aliphatic and aromatic amines.     

Polyelectrolyte complex nanoparticles from chitosan and poly(acrylic acid) and Polystyrene‐block‐poly(acrylic acid)

Interpolymer polyelectrolyte complexes of chitosan (CS) with poly(acrylic acid) homopolymers and polystyrene‐block‐poly(acrylic acid) diblock copolymers were prepared and characterized. The influence of the positive/negative charge balance (charge ratio), pH, and ionic strength were thoroughly studied by dynamic light scattering. The existence of a strong polyelectrolyte effect was also highlighted in this study. Domains of stability, in which nanoparticle sizes are smaller than 100 and 200 nm for complexes of CS with the homopolymer and copolymer, respectively, were identified and confirmed by scanning electron microscopy and atomic force microscopy. The charged nature of the surface of the nanoparticles was evidenced by Zeta potential measurements. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

AUGMENTED LAGRANGIAN METHOD AND OPEN BOUNDARY CONDITIONS IN 2D SIMULATION OF POISEUILLE–BÉNARD CHANNEL FLOW

The main objective of this study is to compare the influence of different boundary conditions upon the incompressible Poiseuille –Bénard channel flow (PBCF) in a 2D rectangular duct heated from below. In a first technical part the algorithm used to carry out this work, based on the augmented Lagrangian method, is presented. The implementation details of the five different open boundary conditions (OBCs) and the periodic boundary conditions (PBCs) tested in the present paper are also given. The study is then carried out for 1800<Ra≤ 10,000, 0<Re≤10 and 0·67≤Pr≤6·4. The five selected OBCs, applied at the outlet of the computational domain, respectively express the following conditions: a square profile for the velocity (OBC1), mass conservation (OBC2), zero second derivative of the horizontal velocity component (OBC3), a mixed boundary condition combining Dirichlet and Neumann conditions (OBC4) and an Orlanski-type boundary condition (OBC5). A good estimation of the perturbation amplitude and of the length of the perturbed zone at the outlet boundary is proposed. It is shown that OBC5 causes very little perturbation in the recirculating flow compared with the other OBCs. © 1997 John Wiley & Sons, Ltd.