Search results for "Thermophoresis"
showing 10 items of 22 documents
Experimental research of surfaced nanoparticle thermal transport in a porous medium
2018
Abstract Experimental research on thermally induced nanocolloid transport in a porous environment is presented. Addition of excess surfactant to a colloid with dispersed phase made of surfaced nanoparticles results in a decrease of effective Soret coefficient in a porous environment. It is shown that with sufficient amounts of surfactant added, this effect extends to a reversal of nanoparticle thermophoretic transport direction, and that the effect shows a tendency of saturation. A mechanism of thermal transport that involves slip velocity of surfactant molecules appearing near pore walls is evaluated as a possible cause of the decrease of Soret coefficient. Effects of temperature on partic…
Non-isothermal separation of ferrofluid particles through grids: Abnormal magnetic Soret effect
2013
Abstract Nanoparticle transport through thin non-isothermal ferrofluid layer between permeable walls is investigated. The transient mass flux is determined from measurements of particle concentration changes in two fluid chambers of different temperatures which are attached on both sides of the layer. Experiments are performed employing fluid samples of small ordinary magnetic Soret effect, which is detected by thermal grating technique. The separation measurements say that a magnetic field, aligned along a temperature gradient, causes a remarkable increase in the mass diffusion coefficient and a simultaneous decrease in particle thermodiffusion mobility. It is proposed that the observed ef…
Formation of magnetoconvection by photoabsorptive methods in ferrofluid layers
2013
Abstract A periodic concentration grating was induced in a layer of ferrofluid by photoabsorption and thermophoresis under the action of the applied uniform magnetic field. The application of the external field causes the appearance of an internal demagnetizing field within the layer and of magnetic forces due to the non-uniform distribution of concentration. The induced magnetic forces cause the appearance of parasitic microconvection within the layer. The experimental observations of the formation stage of the grating are interpreted to explain magnetoconvection, making use of numerical simulations.
Flavonoids as noncompetitive inhibitors of Dengue virus NS2B-NS3 protease: Inhibition kinetics and docking studies
2014
NS2B-NS3 is a serine protease of the Dengue virus considered a key target in the search for new antiviral drugs. In this study flavonoids were found to be inhibitors of NS2B-NS3 proteases of the Dengue virus serotypes 2 and 3 with IC50 values ranging from 15 to 44 μM. Agathisflavone (1) and myricetin (4) turned out to be noncompetitive inhibitors of dengue virus serotype 2 NS2B-NS3 protease with Ki values of 11 and 4.7 μM, respectively. Docking studies propose a binding mode of the flavonoids in a specific allosteric binding site of the enzyme. Analysis of biomolecular interactions of quercetin (5) with NT647-NHS-labeled Dengue virus serotype 3 NS2B-NS3 protease by microscale thermophoresis…
MCC1019, a selective inhibitor of the Polo-box domain of Polo-like kinase 1 as novel, potent anticancer candidate
2019
Polo-like kinase (PLK1) has been identified as a potential target for cancer treatment. Although a number of small molecules have been investigated as PLK1 inhibitors, many of which showed limited selectivity. PLK1 harbors a regulatory domain, the Polo box domain (PBD), which has a key regulatory function for kinase activity and substrate recognition. We report on 3-bromomethyl-benzofuran-2-carboxylic acid ethyl ester (designated: MCC1019) as selective PLK1 inhibitor targeting PLK1 PBD. Cytotoxicity and fluorescence polarization-based screening were applied to a library of 1162 drug-like compounds to identify potential inhibitors of PLK1 PBD. The activity of compound MC1019 against the PLK1…
Thermophoretic separation of a ferrofluid–water emulsion: preliminary experiments
2002
Abstract The Soret effect in an emulsion (microdroplets of hydrocarbon based ferrofluid in water) is evaluated from the separation measurements in vertical thermodiffusion column. The particle concentration in column ends is detected from the resonance frequency of LC oscillators with inductance coils mounted inside the column ends. The Soret coefficient S T of droplets is calculated from the initial part of dynamic separation curves. The measured value S T =−480 K −1 agrees qualitatively well with the calculated one found assuming the Maragoni-type transfer of liquid particles.
Thermal Diffusion and Particle Separation in Ferrocolloids
1999
Results of experiments on thermal diffusion in ferrocolloids are discussed in the paper. The Soret coefficient is evaluated from measurements of particle separation in thermodiffusion column. To interpret the separation curves measured in the presence of a magnetic field, the column theory is modified taking into account for MHD effects of free convection. It is shown that the Hartmann effect in hydrocarbon based colloids as well in ionic magnetic fluids does not influence significantly the particle separation dynamics. From unsteady separation curves positive values of the Soret coefficient of surfacted particles in tetradecane based colloids are calculated. Such direction of particle tran…
Soret coefficient of trace ions determined with electrochemical impedance spectroscopy in a thin cell. Theory and measurement
2018
The tendency of a substance to migrate due to a temperature gradient is known as thermodiffusion or the Soret effect. We believe that this is the first work that describes the study of the Soret effect using electrochemical impedance spectroscopy in a non-isothermal thin cell, and shows how the Soret coefficient can be determined from these measurements. The effect of a temperature gradient in a thin cell is analyzed, both theoretically and experimentally. Our theoretical modeling of the system predicts the effect of key parameters to the impedance spectra. Experimentally we determine the Soret coefficient of the redox couple Fe(CN)64−/Fe(CN)63− in an aqueous KCl solution. It is found that …
The guanidinium group as a key part of water-soluble polymer carriers for siRNA complexation and protection against degradation.
2014
Here, the preparation of a novel block copolymer consisting of a statistical copolymer N-(2-hydroxypropyl) methacrylamide-s-N-(3-aminopropyl) methacrylamide and a short terminal 3-guanidinopropyl methacrylamide block is reported. This polymer structure forms neutral but water-soluble nanosized complexes with siRNA. The siRNA block copolymer complexes are first analyzed using agarose gel electrophoresis and their size is determined with fluorescence correlation spectroscopy. The protective properties of the polymer against RNA degradation are investigated by treating the siRNA block copolymer complexes with RNase V1. Heparin competition assays confirm the efficient release of the cargo in vi…
Magnetic Soret effect in a hydrocarbon based colloid containing surfacted Mn–Zn ferrite particles
1999
Abstract The Soret effect has been investigated in a hydrocarbon based magnetic fluid containing surfacted Mn 0.5 Zn 0.5 Fe 2 O 4 nanoparticles with a magnetic volume concentration of 2.3%. The magnetic fluid fills up a vertical diffusion column which consists of a flat vertical channel between two walls and two reservoirs at the ends of the channel. One wall of the channel is being heated while the another one is cooled, maintaining a temperature gradient over the channel's width that leads to separation of particles due to the Soret effect as well as the convective flow in the channel. The combination of the two mentioned effects brings up a measurable change of the concentration of magne…