Search results for "Bonding"
showing 10 items of 996 documents
Current rectification by nanoparticle blocking in single cylindrical nanopores.
2014
Blocking of a charged pore by an oppositely charged nanoparticle can support rectifying properties in a cylindrical nanopore, as opposed to the usual case of a fixed asymmetry in the pore geometry and charge distribution. We present here experimental data and model calculations to confirm this fundamental effect. The nanostructure imaging and the effects of nanoparticle concentration, pore radius, and salt concentration on the electrical conductance–voltage (G–V) curves are discussed. Logic responses based on chemical and electrical inputs/outputs could also be implemented with a single pore acting as an effective nanofluidic diode. To better show the generality of the results, different ch…
Highly untangled multiwalled carbon nanotube@polyhedral oligomeric silsesquioxane ionic hybrids: Synthesis, characterization and nonlinear optical pr…
2015
Abstract Highly de-bundled multiwalled carbon nanotube (MWCNT) polymer nanohybrids were obtained via ionic assembling of a novel POSS-polyimidazolium-ionic liquid (POSS = polyhedral oligomeric silsesquioxanes) with oxidized MWCNTs. The synthesis, accomplished by a simple bilayer chloroform/water metathetical reaction process, was promoted by the high surfactant properties of POSS-imidazolium-polyionic liquid, which assisted the effective de-bundling, dispersion and purification of the as prepared POSS@MWCNT polymers in organic media, via a surface coating mechanism. The presence of remarkably intense radial breathing modes (RBMs) in Raman spectra, both in solution and as solid, corroborates…
Sedimentation of halloysite nanotubes from different deposits in aqueous media at variable ionic strengths
2019
Abstract Halloysite clay is a natural nanomaterial that is attracting a growing interest in colloidal science. The halloysite aqueous dispersion stability is a key aspect for the configuration of a purification protocol as well as to establish the durability of a formulation. A physico-chemical study demonstrated the role of ionic strength and nanotube characteristic sizes on the sedimentation behavior. We highlighted the importance of the electrostatic repulsions exercised between the particles in the settling process. A protocol for image analysis has been proposed to provide robust information from time resolved optical images on the suspensions. In conclusion, we managed to correlate mi…
Voltage-activated transport of ions through single-walled carbon nanotubes
2017
International audience; Ionic transport through single-walled carbon nanotubes (SWCNTs) is promising for many applications but remains both experimentally challenging and highly debated. Here we report ionic current measurements through microfluidic devices containing one or several SWCNTs of diameter of 1.2 to 2 nm unexpectedly showing a linear or a voltage-activated I-V dependence. Transition from an activated to a linear behavior, and stochastic fluctuations between different current levels were notably observed. For linear devices, the high conductance confirmed with different chloride salts indicates that the nanotube/water interface exhibits both a high surface charge density and flow…
Conformational changes in acetylcholine binding protein investigated by temperature accelerated molecular dynamics.
2014
Despite the large number of studies available on nicotinic acetylcholine receptors, a complete account of the mechanistic aspects of their gating transition in response to ligand binding still remains elusive. As a first step toward dissecting the transition mechanism by accelerated sampling techniques, we study the ligand-induced conformational changes of the acetylcholine binding protein (AChBP), a widely accepted model for the full receptor extracellular domain. Using unbiased Molecular Dynamics (MD) and Temperature Accelerated Molecular Dynamics (TAMD) simulations we investigate the AChBP transition between the apo and the agonist-bound state. In long standard MD simulations, both confo…
Silicatein conjugation inside nanoconfined geometries through immobilized NTA–Ni(ii) chelates
2013
The chemical modification and bioconjugation processes inside confined geometries by His-tagged silicatein promote sensitive changes in the polarity and surface charge density that mainly contribute to the ionic current rectification properties of the single conical nanopores.
Aminolysis of monoacetyl derivatives of 2,2′ -dihydroxydiphenylmethanes
1974
A neighboring group effect was found for the aminolysis of the second acetyl group in acetates of 2,2′-dihydroxydiphenylmethane derivatives containing a nitrophenol and a methylphenol unit. Kinetic measurements with an excess of n-butylamine in dioxane were done with 2-(2-hydroxy-3, 5-dinitrobenzyl)-4-methylphenyl acetate (1), 2-(2-hydroxy-5-nitro-benzyl)-4-methylphenyl acetate (2), and 2-(2-hydroxy-3-nitro-5-methylbenzyl)-4-methyl-phenyl acetate (3). The maximum rate was found for compound 2. When the concentration of n-butylamine was varied over a large range, the results obtained for compound 2 could be explained best, by assuming that the acetyl group in the methylphenol unit is aminoli…
Hexachlororhenate(IV) salts of organic radical cations
2005
Abstract The ionic salts ( p -rad) 2 [ReCl 6 ] ( 1 ) and ( m -rad) 2 [ReCl 6 ] ( 2 ) ( p / m -rad = 2-(4/3- N -methylpyridinium)-4,4,5,5-tetramethyl-4,5-dihydro-1 H -imidazol-1-oxyl-3- N -oxide) have been prepared and their crystal structures determined by single-crystal X-ray diffraction. The nitronyl nitroxide cations in compound 1 show a layered disposition, whereas the [ReCl 6 ] 2− units are placed between these layers. The nitronyl nitroxide cations in compound 2 adopt an hexagonal array but they do not result in layers. Bulk magnetic properties of 1 and 2 have been investigated in the temperature range 2–300 K. Both compounds show weak but significant intermolecular antiferromagnetic …
A Comparison of Special Bonding Techniques for Transmission and Distribution Cables under Normal and Fault Conditions
2021
In this article, a review of the existing special bonding techniques for medium voltage and high-voltage cables is presented. Special bonding techniques have the purpose of reducing sheath currents, thereby limiting copper losses and the reduction of the ampacity of cables. The literature review shows various bonding techniques and how these have evolved over the years thanks to new technologies. Simulations of each technique are performed in MATLAB/Simulink, to compare their strengths and drawbacks both under normal conditions and in the presence of a single-line-to-ground fault.
Detector-electrode for alpha spectrometry in water sample, numerical and early feasibility investigation toward thermocompression bonding assembly pr…
2020
International audience; This study focuses on the feasibility of a detector-electrode for direct alpha measurement in aqueous samples. Such a device could be made by adding a boron doped diamond electrode on top of a standard silicon detector, with bonding and insulating layers. The impact of these different layers has been investigated by Monte-Carlo simulation (MCNP6), to find a compromise between alpha detection of the silicon, electrode and shielding properties of the diamond. The assembly process involving thermocompression between both substrates was successfully achieved under a clean room conditions.