Simulation Studying Effects of Multiple Primary Aberrations on Donut-shaped Gaussian Beam

In this paper, we demonstrate the variation of donut-shaped depletion pattern which influenced by multiple primary aberrations. The simulation is base on a common stimulation emission of depletion (STED) system composed by Gaussian laser and vortex phase plate. The simulation results are helpful guidelines for analyzing the aberration of depletion patterns in real situations.

Direct observation of λ-DNA molecule reversal movement within microfluidic channels under electric field with single molecule imaging technique

The electrodynamic characteristics of single DNA molecules moving within micro-/nano-fluidic channels are important in the design of biomedical chips and bimolecular sensors. In this study, the dynamic properties of λ-DNA molecules transferring along the microchannels driven by the external electrickinetic force were systemically investigated with the single molecule fluorescence imaging technique. The experimental results indicated that the velocity of DNA molecules was strictly dependent on the value of the applied electric field and the diameter of the channel. The larger the external electric field, the larger the velocity, and the more significant deformation of DNA molecules. More meaningfully, it was found that the moving directions of DNA molecules had two completely different directions：（i） along the direction of the external electric field, when the electric field intensity was smaller than a certain threshold value;（ii） opposite to the direction of the external electric field, when the electric field intensity was greater than the threshold electric field intensity.The reversal movement of DNA molecules was mainly determined by the competition between the electrophoresis force and the influence of electro-osmosis flow. These new findings will theoretically guide the practical application of fluidic channel sensors and lab-on-chips for precisely manipulating single DNA molecules.

A kind of double-sided porous anodic alumina membrane fabricated with the three-step anodic oxidation method

The porous anodic alumina membranes(PAAMs)have been successfully used as templates for the fabrication of functional nano-materials due to their outstanding regularity and physicochemical properties.In this paper,a transparent double-sided anodic alumina membrane with ultra-thin aluminum substrate was fabricated with the three-step anodic oxidation method in the oxalic acid electrolyte.The characters such as the top-surface morphology,membrane thickness,and depth of nanopores of this three-layer(Al2O3-Al-Al2O3)sandwiched nano-structure were controllable through regulating the main anodic oxidation conditions,e.g.,anodic oxidation time of various steps,coating remove process.The experiments data revealed that the aluminum substrate is exponential declined with the oxidation time when it was approximately reduced by a few micrometers.This new double-sided anodic alumina membrane can be used as the high-quality functional field emission materials and templates.

Studying the current properties of buffer solution through micro-fluidic channels driven with the pulse bias

In the research of bio-molecular chips and sensors,extra electric biases are most often employed to control and manipulate the DNA and protein molecules moving through micro/nano-fluidic channels.In order to accurately and flexibly control the bio-molecules as they move within the channels,a clear understanding of how the current changes within the buffer solution caused by an applied bias is fundamental.In this report,the current changed value of different buffer solutions,e.g.,KCl,TE,and TBE was systematically studied with real-time monitoring and quantitative analysis in the situation of the buffers moving through a fluidic channel with a 5 m inner diameter,driven by biases of 50 or 100 mV.The results revealed that the relationship between the current changed value and the pause interval of the applied electric field is highly consistent with the Hill Equation,which is helpful for accurately detecting and manipulating single biomolecules in microfluidic sensors and biochips.