Effect of voltage polarity and supply frequency on properties of plasma contacting liquid electrode and gold nanoparticle synthesis

Plasma contacting with liquid provides many charged particles and reactive species into the liquid. The difficulty in controlling or selecting each specific species has significantly limited its applications in industry. Here, we present a study on using voltage polarity to regulate the type of charged particles absorbing from plasma into liquid. Detailed understanding of the processes at the plasma-liquid interface, electrolysis due to switching in voltage polarity was investigated via a visual pH observation, measuring the concentration of H2O2 and solvated electrons. The results indicated that changing in voltage polarity strongly affects the plasma properties, chemical properties, and electrolysis process in liquid, and further in the types of reducing species for gold nanoparticle synthesis. The results also showed using a suitable frequency could improve the efficiency of absorption of H2O2from plasma into the bulk liquid and the yield in the production of gold nanoparticles. The results provide a way to select desired species from plasma into the liquid for a distinct purpose and accompanying other properties in the system of plasma contacting with liquid.

Nucleotide Dynamics During Flossing of Polycation-DNA-Polycation through a Nanopore using Molecular Dynamics

The full potential of solid state nanopores is yet to be realized for genome sequencing. Due to its robustness it can handle strong voltage amplitude and frequency. The effect of strong alternating voltage on the dynamics of nucleotides during translocation has been explored. We proposed a setup consisting of single stranded DNA covalently linked with symmetric polycations at both ends fashioned after the proposal of Kasianowicz. Such a setup allows for repeated back and forth motion of the DNA along the nanopore (1.45 nm diameter and 1.53 nm thick) by simply switching the voltage polarity if the polycation tail is sufficiently long (greater than or equal to 10) and the applied voltage is below 0.72 volts, but the average residence time of the nucleotides are too small to be of any practical use (6-30 ns). When alternating voltage of higher frequency is applied, it enhances the average residence time of the nucleotides by an order of magnitude to approximately 0.1 microseconds relative to direct voltage but the individual trajectories are too stochastic. Since, we are able to collect repeated read on the dynamics of individual nucleotides, we obtained the most probable time of appearance of a nucleotide within the nanopore. With such construct we were able to get almost linear dependence of most probable time versus nucleotide index, after gaussian fitting.

3D jet writing of mechanically actuated tandem scaffolds

The need for high-precision microprinting processes that are controllable, scalable, and compatible with different materials persists throughout a range of biomedical fields. Electrospinning techniques offer scalability and compatibility with a wide arsenal of polymers, but typically lack precise three-dimensional (3D) control. We found that charge reversal during 3D jet writing can enable the high-throughput production of precisely engineered 3D structures. The trajectory of the jet is governed by a balance of destabilizing charge-charge repulsion and restorative viscoelastic forces. The reversal of the voltage polarity lowers the net surface potential carried by the jet and thus dampens the occurrence of bending instabilities typically observed during conventional electrospinning. In the absence of bending instabilities, precise deposition of polymer fibers becomes attainable. The same principles can be applied to 3D jet writing using an array of needles resulting in complex composite materials that undergo reversible shape transitions due to their unprecedented structural control.

On a separation voltage polarity switching transient capillary isotachophoresis method for higher sample loading capacity and better separation performance

Mechanism of a PS-tCITP method with higher sample loading capacity and better separation performance.

Direct Coupled PV Panel with ĆUK Converter for DC Load Applications

The PV systems are becoming gradually more common in distribution and generation systems. The direct coupled CUK converter for DC load applications is connected with PV panel. The ĆUK converter convert DC- DC voltage, in which magnitude of voltage output is not more than or higher than the magnitude of voltage input also the input voltage polarity is reverse to that of output voltage. The ĆUK converter is frequently customized for additional functions like simple transformer separation, high current protection, less ripple current and transfers the power regularly through capacitor. As per the research on the ĆUK converters has rigorous minor switching loss, capable to give unity power factor, decrease in element size, improving efficiency of the system, etc. Operation of ĆUK converter is relatively unusual with that of PWM converters. The effectiveness of proposed methods is to validate ĆUK converter in MATLAB/ SIMULINK.