AC electrokinetic isolation and detection of extracellular vesicles from dental pulp stem cells: Theoretical simulation incorporating fluid mechanics

Extracellular vesicles (EVs) are cell-derived nanoscale vesicles involved in intracellular communication and the transportation of biomarkers. EVs released by mesenchymal stem cells have been recently reported to play a role in cell-free therapy of many diseases. However, the demand for better research tools to replace the tedious conventional methods used to study EVs is getting stronger. EVs' manipulation using alternating current (AC) electrokinetic forces in a microfluidic device has appeared to be a reliable and sensitive diagnosis and trapping technique. Given that different AC electrokinetic forces may contribute to the overall motion of particles and fluids in a microfluidic device, EVs' electrokinetic trapping must be examined considering all dominant forces involved depending on the experimental conditions. In this paper, AC electrokinetic trapping of EVs using an interdigitated electrode arrays is investigated. A 2D numerical simulation incorporating the two significant AC electrokinetic phenomena (Dielectrophoresis and AC electroosmosis) has been performed. Theoretical predictions are then compared with experimental results and allow for a plausible explanation of observations inconsistent with DEP theory. It is demonstrated that the inconsistencies can be attributed to a significant extent to the contribution of the AC electroosmotic effect.     

Estimation of natural gas contribution in indoor 222Rn concentration level in residential houses

Journal of Radioanalytical and Nuclear Chemistry - The effect of natural gas use on indoor radon concentrations was studied in the dwelling of two cities in Cyprus using an AlphaGUARD radon...     

Electrocatalytic and selective determination of d‐penicillamine in the presence of tryptophan using a benzoylferrocene‐modified carbon nanotube paste electrode

Two amino acids – d ‐penicillamine (D‐PA) and tryptophan (TRP) – could be simultaneously determined in an aqueous solution (pH 7.0) using a novel benzoylferrocene‐modified carbon nanotube paste electrode. The results indicate that the electrode is efficient in terms of its electrocatalytic activity for the oxidation of D‐PA, leading to an overpotential reduction by more than 155 mV. Using square wave voltammetry, measurement of D‐PA and TRP in one mixture could be done independently from each other with a potential difference of about 205 mV. The proposed electrochemical sensor exhibited a linear calibration plot ranging from 1.0 × 10^?6 to 8.0 × 10^?4 m with a detection limit of 1.3 × 10^?7 m for D‐PA. Finally, the proposed method was applied to the determination of D‐PA in a D‐PA capsule. Copyright © 2012 John Wiley & Sons, Ltd.     

Experimental measurement and thermodynamic modeling of liquid-liquid equilibrium for 1-pentanol + water + NaNO3 at 298.15 and 308.15 K

Experimental measurements have been performed for liquid-liquid equilibria in aqueous systems containing 1-pentanol and sodium nitrate at temperatures of 298.15 and 308.15 K and at atmospheric pressure. The results have been modeled using the extended UNIQUAC model and also a modified version of this model. Relevant model parameters have been adjusted using the experimental data. Both models are capable of correlating the experimental data with an average deviation of less than 0.8 weight percent, with the modified model producing slightly better results. The predictive nature of the models has also been verified.     

Selective Oxidation of Sulfides to Sulfoxides using H2O2 Catalyzed by p-Toluenesulfonic Acid (p-TsOH) Under Solvent-Free Conditions

Abstract

An efficient, chemoselective, and environmental friendly procedure for the oxidation of sulfides to sulfoxides is described. Various types of aromatic and aliphatic sulfides are selectively oxidized to sulfoxides in good to excellent yields using 30% H₂O₂ in the presence of catalytic amounts of a p-TsOH under solvent-free conditions at room temperature.     

Ultratrace determination of lead,cadmium and copper in environmental and biological samples by atomic absorption spectrometry after their separation and preconcentration using octadecyl silica membrane disks modified with a new n–s schiff base

Pb(II), Cd(II) and Cu(II) ions were separated and preconcentrated by solid-phase extraction on octadecyl-bonded silica membrane disks modified with a new S–N-containing Schiff base (bis-2-thiophenal propandiamine) (BTPD) followed by elution and atomic absorption spectrometric detection. The method was applied as a separation and detection method for lead(II), cadmium(II) and copper(II) in environmental and biological samples. Extraction efficiency and the influence of sample matrix, flow rate, pH, and type and minimum amount of stripping acid were investigated. The maximum capacity of the membrane disks modified by 4?mg of BTPD was found to be 668 ± 10, 480 ± 8 and 454 ± 7?µg of lead, cadmium and copper, respectively. The limit of detection of the proposed method is 0.25, 0.01 and 0.02?ng/mL for lead, cadmium and copper, respectively.     

Synthesis of tertiary aryl amines of various aryl halides and secondary amines using ortho‐palladated complex of tribenzylamine

The activity of dimeric [Pd{C₆H₄(CH₂N(CH₂Ph)₂)} (μ‐Br)]₂ complex as an efficient, air‐ and moisture‐tolerant catalyst was investigated in amination reactions of various aryl halides with secondary amines. Substituted tertiary aryl amines were produced in excellent yields and short reaction times using catalytic amounts of this dimeric complex in DMSO at 120°C. Copyright © 2013 John Wiley & Sons, Ltd.     

Reductive Alkylation of Pentaphenylthiopyrylium Perchlorate: An Approach to Regiospecific Synthesis of Hexasubstituted 2H-Thiopyrans

Regiospecific synthesis of some new hexasubstituted 2H-thiopyrans was examined by reductive alkylation of pentaphenylthiopyrylium perchlorate and found to be in quantitative yields. Under our experimental conditions, the formation of unstable thiabenzene intermediates could be observed through detectable color changing during the addition of C-nucleophiles to thiopyrylium perchlorate. Moreover, the effect of phenyl groups on the 3,5-positions of thiopyrylium perchlorate on the regioselectivity were compared with other analogs having methyl groups on the same positions.