Improvement of Background Solution for Optically Induced Dielectrophoresis-Based Cell Manipulation in a Microfluidic System

Optically induced dielectrophoresis (ODEP) is effective for cell manipulation. However, its utilization has been limited by the requirement of solution with low conductivity. This issue has been ignored in ODEP-relevant studies. To address this issue, this study aims to investigate to what extent the cell viability and performance of ODEP-based cell manipulation are affected by low conductivity conditions. Additionally, this study aims to modify sucrose solutions to reduce the impacts caused by low-conductivity solutions. Results revealed the use of sucrose solution in ODEP operation could significantly reduce the viability of the manipulated cells by 9.1 and 38.5% after 2- and 4-h incubation, respectively. Prolonged operation time (e.g., 4 h) in sucrose solution could lead to significantly inferior performance of cell manipulation, including 47.2% reduction of ODEP manipulation velocity and 44.4% loss of the cells manipulatable by ODEP. The key finding of this study is that the use of bovine serum albumin (BSA)-supplemented sucrose solution (conductivity: 25–50 μS cm−1) might significantly increase the cell viability by 10.9–14.8% compared with that in sucrose solution after 4 h incubation. Moreover, the ODEP manipulation velocity of cells in the BSA-supplemented sucrose solution (conductivity: 25 μS cm−1) was comparable to that in sucrose solution during 4-h incubation. More importantly, compared with sucrose solution, the use of BSA-supplemented sucrose solution (conductivity: 25–50 μS cm−1) contributed high percentage (80.4–93.5%) of the cells manipulatable by ODEP during 4-h incubation. Overall, this study has provided some fundamental information relevant to the improvement of background solutions for ODEP-based cell manipulation.

Influence of solution properties and gas addition on hydrogen peroxide production by a novel plasma source

The paper evaluates concentration of hydrogen peroxide produced by a novel pin-hole plasma source in electrolyte solutions with or without gas addition. An effective production rate of hydrogen peroxide is decreased by the increased argon as well as oxygen flow rate through the plasma region. Further, it is enhanced by higher solution conductivity while it is decreased in the strongly basic conditions with the highest pH values.

Динамическая модель подводного разряда

A dynamic model of an underwater electric discharge is presented. The method is based on a mathematical description of the dependence of the solution conductivity on its thickness during the formation of a vapor-gas bubble. The time dependences of the current and the voltage drop across the cell were calculated using expressions relating the current and voltage to the resistance (conductivity) of the solution and taking into account the periodicity of the processes. The presented model makes it possible to accurately describe the dynamic characteristics of underwater discharges based on the physicochemical properties of the solution, which makes it possible to predict the behavior of the discharge when using solutions with specified properties.

Effect of Concentration and Nozzle-Collector Distance on the Morphology of Nanofibers

Electrospinning is a method for making nanofibers by utilizing an electric field produced by high voltage. Electrospinning process is influenced by several factors including the concentration of the solution, conductivity, viscosity, volatility, surface tension, electric field strength between the needle and the collector, feed / flow rate and environmental conditions which include temperature, humidity and air composition. Electrospinning parameters are used to optimize the size of the nanofiber, concentration of the solution and the distance of the nozzle to collector. In the process of electrospinning PVA solutions that are handled by high dc voltage gets an electrostatic force and electric field. The solution will elongate to form a Taylor cone, then a jet of polymer will undergo thinning and evaporation to form fibers in the collector. The results of morphological analysis using scanning electron microscopy (SEM) showed that the smallest nanofiber was obtained at a solution concentration of 5%, dc high voltage10 kV, and the distance of the nozzle to collector was 15 cms.

Effect of Cu2+ on the Activation to Muscovite Using Electrochemical Pretreatment

In this study, electrochemistry pretreatment flotation of muscovite was carried out and the flotation behavior and mechanism of muscovite in the system of sodium oleate and Cu2+ion was characterized by solution pH value detection, solution conductivity detection, zeta potential, infrared spectrum and the electronic energy spectrum. The results indicated that under the conditions of muscovite mass of 10.00 g, pulp mass concentration of 13.33%, flotation speed of 1750 r/min, sodium oleate concentration of 9.20 × 10−4 mol/L and Cu2+ concentration of 6 × 10−5 mol/L, electrochemical pretreatment of Cu2+ could strengthen the activation of muscovite. Electrochemical pretreatment of Cu2+ solution can inhibit the hydrolysis of copper ions, increase the content of Cu2+ in the solution, strengthen the adsorption of Cu2+ on the muscovite surface, and enhance the electrostatic adsorption of sodium oleate on the muscovite surface, thereby strengthening the physical and chemical adsorption of sodium oleate on the muscovite surface.