Search results for "ionic"
showing 10 items of 2016 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…
Modelling of natural and synthetic polyelectrolyte interactions in natural waters.
2006
In this paper SIT and Pitzer models are used for the first time to describe the interactions of natural and synthetic polyelectrolytes in natural waters. Measurements were made potentiometrically at 25 °C in single electrolyte media, such as Et4NI and NaCl (for fulvic acid 0.1 < I /mol L− 1 < 0.75), and in a multi-component medium simulating the composition of natural waters at a wide range of salinities (for fulvic and alginic acids: 5 < S < 45) with particular reference to sea water [Synthetic Sea Water for Equilibrium studies, SSWE]. In order to simplify calculations, SSWE was considered to be a “single salt” BA, with cation B and anion A representing all the major cations (Na+, K+, Mg2+…
Natural eutectogels: sustainable catalytic systems for C–C bond formation reactions
2021
Natural eutecto gels were prepared combining properties of amino acids with the ones of deep eutectic solvents. Soft materials obtained were fully characterised determining the gel-sol transition temperatures and analysing mechanical and morphological features through rheological measurements and polarised optical microscopy. All eutecto gels were tested as catalytic reaction media for the enantioselective aldol reaction and, the best performing one was also used to carry out the Michael addition. In both cases, eutecto gels proved to have a great potential as sustainable reaction media, allowing to perform processes under mild conditions, obtaining excellent yields and, in some cases, also…
Modeling the sorption of Np(V) on Na-montmorillonite – effects of pH, ionic strength and CO2
2019
Abstract Results from batch type experiments were modeled using the 2 SPNE SC/CE model developed by Bradbury and Baeyens. This work focused on the applicability of this model to the sorption of Np(V) on Na-montmorillonite under high saline conditions (0.1–3.0 M NaCl) in the pH range of 2–10 and in the presence of dissolved CO2 (p(CO2) = 10−3.3 atm). Under ambient air conditions two additional surface complexation species had to be taken into account, which are ternary species involving one carbonate ligand (≡SONpO2(CO3)2−, ≡SONpO2(CO3)Na−). The gained set of complexation parameters was successfully tested over a wide range of Np(V) concentrations (10−4 to 10−12 M) under Ar atmosphere and am…
Evidence for bilateral vagal innervation of postganglionic parasympathetic neurons in chicken heart
1983
Stimulation of the cervical vagus nerves caused an output of acetylcholine (ACh) from the isolated chicken heart, which almost exclusively was released from the postganglionic neurons: (+)-tubocurarine (3 X 10(-14) M) reduced the output to 12 +/- 6% (n = 7) of the control. Stimulation of the two nerve trunks ws equally effective in releasing ACh.--Evidence that a large number of postganglionic neurons receives bilateral innervation was based on two experimental series. (1). The sum of the ACh outputs evoked by unilateral (separate) nerve stimulation of the right and the left vagus was higher than the bilaterally evoked output (100%) and increased with increasing frequencies (10, 20 and 40 H…
Impact of heteroptera pentatomidae feeding and oviposition on photosynthesis of herbaceous plants and egg parasitoids host location
2009
The present study was designed to examine the effect of heteroptera pentatomidae feeding and/or oviposition on photosynthesis. Murgantia histrionica and Nezara viridula were fed on Brassica and Phaseolus plants, respectively. The changes in photosynthetic gas exchange and chlorophyll fluorescence parameters were followed immediately after the feeding as well as during the post-feeding period (24, 48 and 72 h). Murgantia feeding caused visible damage on leaf lamina, whereas this was not the case with Nezara feeding. In both cases a substantial decrease (50%) in photosynthesis was observed, which was partially restored only in Phaseolus plants by the end of the experiment. By using high resol…
Poly(alkylidenamines) dendrimers as scaffolds for the preparation of low-generation ruthenium based metallodendrimers
2011
The aim of this article is to highlight the use of nitrile-functionalized poly(alkylidenamines) dendrimers as building blocks for the preparation of low-generation ruthenium based cationic metallodendrimers having in view potential biomedical applications. Air-stable poly(alkylidenamines) nitrile dendrimers, peripherally functionalized with the ruthenium moieties [Ru(η5-C5H5)(PPh3)2]+ or [RuCl(dppe)2]+, have been prepared, characterized and are being studied for their anticancer activity. The followed strategy is based on the biological advantages associated with low-generation dendrimers, the known activity of ruthenium compounds as anticancer drugs and the stability of these dendrimers at…