A dielectrophoretic continuous flow sorter using integrated microelectrodes coupled to a channel constriction

In this article, we propose a novel dielectrophoretic continuous flow sorter using planar micro electrodes coupled to a channel constriction. This design enables a high particle sorting efficiency at low voltages while relying on a simple fabrication and integration process. We have numerically simulated the AC electrokinetic effects and the fluid behavior to predict particle trajectories. Simulation results are in accordance with experimental data: 10 and 5 μm polystyrene beads were continuously sorted with <2% errors at flow speeds of 100 μm/s. We were also able to change the particle buffer while sorting beads. Finally, to demonstrate the interest of our device for cell sorting, we also sorted dead and living yeast cells according to their different dielectric properties. Living cell concentration was enriched by a factor of 4 versus dead cell concentration after passing the sorting device.     

Supramolecular “Double‐Propeller” Dimers of Hexanuclear CuII/LnIII Complexes: A {Cu3Dy3}2 Single‐Molecule Magnet

Propelling magnetism : Supramolecular organization leads to a remarkable dodecanuclear {Cu₃Dy₃}₂ cluster with a “double–propeller” shape (see picture). The linkages of the CuDy units, both intramolecular and supramolecular, appear to be responsible for a drastic change in the single molecule magnetic behavior.

     

Carbon Xerogel Nanostructures with Integrated Bi and Fe Components for Hydrogen Peroxide and Heavy Metal Detection

Multifunctional Bi- and Fe-modified carbon xerogel composites (CXBiFe), with different Fe concentrations, were obtained by a resorcinol–formaldehyde sol–gel method, followed by drying in ambient conditions and pyrolysis treatment. The morphological and structural characterization performed by X-ray diffraction (XRD), Raman spectroscopy, N₂ adsorption/desorption porosimetry, scanning electron microscopy (SEM) and scanning/transmission electron microscopy (STEM) analyses, indicates the formation of carbon-based nanocomposites with integrated Bi and Fe oxide nanoparticles. At higher Fe concentrations, Bi-Fe-O interactions lead to the formation of hybrid nanostructures and off-stoichiometric Bi₂Fe₄O₉ mullite-like structures together with an excess of iron oxide nanoparticles. To examine the effect of the Fe content on the electrochemical performance of the CXBiFe composites, the obtained powders were initially dispersed in a chitosan solution and applied on the surface of glassy carbon electrodes. Then, the multifunctional character of the CXBiFe systems is assessed by involving the obtained modified electrodes for the detection of different analytes, such as biomarkers (hydrogen peroxide) and heavy metal ions (i.e., Pb²⁺). The achieved results indicate a drop in the detection limit for H₂O₂ as Fe content increases. Even though the current results suggest that the surface modifications of the Bi phase with Fe and O impurities lower Pb²⁺ detection efficiencies, Pb²⁺ sensing well below the admitted concentrations for drinkable water is also noticed.     

Polysilane‐Cycloimmonium Salts: New Materials for Organic Semiconductors

Summary: This work presents the first synthesis of a new polymer obtained by catalytic addition of the Si H groups of a poly[methyl(H)silane‐co‐methylphenylsilane] backbone to an N‐(allyl)cycloimmonium salt. This hybrid polymer was characterized by spectroscopic analysis, thermogravimetric analysis and gel‐permeation chromatography (GPC). The pendant N‐(allyl)cycloimmonium segments lead to the formation of molecular dipoles, as evidenced by electrical polarization experiments.

Structure of the polysilane‐cycloimmonium salt.     

A high anisotropy barrier in a sulfur-bridged organodysprosium single-molecule magnet

The sulfur-bridged dimers [{Cp'(2)Ln(μ-SSiPh(3))}(2)] (Ln=Gd (1), Dy (2); Cp'=η(5)-C(5)H(4)Me) were synthesized by the transmetalation reactions between [Cp'(3)Ln] and Ph(3)SiSLi. Compound 2 is a single-molecule magnet with slow relaxation of magnetization up to 40 K and an anisotropy barrier of U(eff) =133 cm(-1). Insight into the SMM properties of 2 and closely related SMMs has been obtained using ab initio calculations.     

Redox Switches for Single‐Molecule Magnet Activity: An Ab Initio Insight

A dinuclear Co^II complex ( 1 ) featuring unprecedented anodic and cathodic switches for single‐molecule magnet (SMM) activity has been recently investigated (J. Am. Chem. Soc. 2013 , 135, 14670). The presence of sandwiched radicals in different oxidation states of this compound mediates magnetic coupling between the high‐spin (S=3/2) cobalt ions, which gives rise to SMM activity in both the oxidized ([ 1 (OEt₂)]⁺) and reduced ([ 1 ]^?) states. This feature represents the first example of a SMM exhibiting fully reversible, dual ON/OFF switchability. Here we apply ab initio and broken‐symmetry DFT calculations to elucidate the mechanisms responsible for magnetic properties and magnetization blocking in these compounds. It is found that due to the strong delocalization of the magnetic molecular orbital, there is a strong antiferromagnetic interaction between the radical and cobalt ions. The lack of high axiality of the cobalt centres explains why these compounds possess slow relaxation of magnetization only in an applied dc magnetic field.     

On the electrochemical behavior of selanyl azulenes

Journal of Solid State Electrochemistry - The electrochemical behavior of substituted 1-phenylselanyl azulenes has been established by cyclic, differential pulse, and rotating disk electrode...     

Non-linear response of geometrically imperfect sandwich curved panels under thermomechanical loading

This paper deals with the non-linear response of sandwich curved panels exposed to thermomechanical loadings. The mechanical loads consist of compressive/tensile edge loads, and a lateral pressure while the temperature field is assumed to exhibit a linear variation through the thickness of the panel. Towards obtaining the equations governing the postbuckling response, the Extended Galerkin’s Method is used. The numerical illustrations concern doubly curved, circular cylindrical and as a special case, flat panels, all the edges being simply supported. Moveable and immoveable tangential boundary conditions in the directions normal to the edges are considered and their implications upon the thermomechanical load-carrying capacity are emphasized. Effects of the radii of curvature and of initial geometric imperfections on the load-carrying capacity of sandwich panels are also considered and their influence upon the intensity of the snap-through buckling are discussed. It is shown that in special cases involving the thermomechanical loading and initial geometric imperfection, the snap-through phenomenon can occur also in the case of flat sandwich panels.