Self-Induced Crystallization in Charged Gold Nanoparticle-Semiflexible Biopolyelectrolyte Complexes

Mixing negatively charged polyelectrolyte (PEL) with positively charged gold nanoparticles (Au NPs) in aqueous solution results in electrostatics complexes of different shapes and compactness. Here, when complexing with a semirigid PEL hyaluronic acid (HA), we obtain crystals made of nanoparticles in a new region of the phase diagram, as evidenced by small-angle X-ray scattering (SAXS). The Au NPs were initially well dispersed in solution; their size distribution is well controlled but does not need to be extremely narrow. The bacterial hyaluronic acid, polydispersed, is commercially available. Such rather simple materials and mixing preparation produce a highly ordered crystalline phase of electrostatic complexes. The details of the interactions between spherical nanoparticles and linear polymer chains remain to be investigated. In practice, it opens a completely new and unexpected method of complexation. It has high potential, in particular because one can take advantage of the versatility of Au NPs associated with the specificity of biopolymers, varied due to natural biodiversity

HETU: a new high-resolution stress and texture neutron diffractometer at China Mianyang Research Reactor

International audienceHETU is a new high-resolution stress and texture neutron diffractometer installed at the C1 neutron guide at China Mianyang Research Reactor. The diffractometer is designed for precise residual stress and texture analysis of engineering components, as well as in situ investigations under various sample environments for engineering materials. The wavelength range of monochromatic incident neutrons is 1.634–5.800 Å, provided either by a double-focusing perfect single-crystal silicon monochromator in high instrument resolution mode or by a highly oriented pyrolytic graphite monochromator in high neutron flux mode. The intrinsic peak widths of HETU have been measured using a standard silicon powder sample, and residual stress measurements of an aluminium alloy shrink-fit ring and plug have been carried out. These results demonstrate that HETU is a reliable and appropriately designed diffractometer for promoting materials investigation

Data for Magneto-structural correlations in Ni^{2+}-halide ··· halide-Ni^{2+} chains

We present the magnetic properties of a new family of S = 1 molecule-based magnets, NiF2(3,5-lut)4·2H2O and NiX2(3,5-lut)4, where X = HF2, Cl, Br, or I (lut = lutidine C7H9N). Upon creation of isolated Ni–X···X–Ni and Ni–F–H–F···F–H–F–Ni chains separated by bulky and nonbridging lutidine ligands, the effect that halogen substitution has on the magnetic properties of transition-metal-ion complexes can be investigated directly and in isolation from competing processes such as Jahn–Teller distortions. We find that substitution of the larger halide ions turns on increasingly strong antiferromagnetic interactions between adjacent Ni2+ ions via a novel through-space two-halide exchange. In this process, the X···X bond lengths in the Br and I materials are more than double the van der Waals radius of X yet can still mediate significant magnetic interactions. We also find that a simple model based on elongation/compression of the Ni2+ octahedra cannot explain the observed single-ion anisotropy in mixed-ligand compounds. We offer an alternative that takes into account the difference in the electronegativity of axial and equatorial ligands