The target region focused imaging method for scanning ion conductance microscopy.

Scanning ion conductance microscopy (SICM) has developed rapidly and has wide applications in biomedicine, single-cell science and other fields. SICM scanning speed is limited by the conventional raster-type scanning method, which spends most of time on imaging the substrate and does not focus enough on the target area. In order to solve this problem, a target region focused (TRF) method is proposed, which can effectively avoid the scanning of unnecessary substrate areas and enables SICM to image the target area only to achieve high-speed and effective local scanning. TRF method and conventional hopping mode scanning method are compared in the experiments using breast cancer cells and rat basophilic leukemia cells as experimental materials. It was demonstrated that our method can reduce the scanning time for a single sample image significantly without losing scanning information or compromising the quality of imaging. The TRF method developed in this paper can provide an efficient and fast scanning strategy for improving the imaging performance of SICM systems, which can be applied to the dynamic features of cell samples in the fields of biology and pharmacology analysis.

Investigating the effects of solution viscosity on the stability and success rate of SECCM imaging.

Due to the capability of simultaneously detecting the morphology and electrochemical information of samples and limiting the electrochemical reaction to a range approximately the size of the inner diameter of the pipette tip opening, scanning electrochemical cell microscopy (SECCM) enables higher precision local electrochemical measurement and surface material delivery and has been demonstrating unique advantages and broad application prospects. However, the meniscus droplet at the pipette tip of SECCM is equivalent to the opening radius of the pipette tip, which is usually tens of nanometers to hundreds of nanometers. The tiny meniscus droplet makes it susceptible to evaporation and crystallization, which increases the likelihood of the pipette colliding with the sample during the scanning process, resulting in the failure of scanning. In this paper, the influence of solution viscosity on the shape variation of the droplet at the tip during the movement of the pipette of SECCM was studied by finite element analysis. It is proved that the increase of solution viscosity is helpful in reducing the shape variation of the droplet at the tip during the movement of the pipette. Then scanning experiments were carried out using a flat Au substrate and Au substrates with rounded triangle and rounded rectangular convex structures as the samples. According to the experimental results, increasing solution viscosity improves scanning success rates and scanning quality and effectively lowers the MSE of the scanning results. The experimental results also show that SECCM can image at a higher speed when the solution's viscosity increases since the deformation of the droplet at the tip is less than with a typical solution.

[Start-up and maintenance method for short-cut advanced nitrogen removal process in a pilot-scale reactor at low temperature].

In order to test the start-up and maintain method for short-cut advanced nitrogen removal process at low temperature, this study used a pilot-scale SBR process with a working volume of 7.0 m3 to treat domestic wastewater. Real-time control strategy based on blower frequency (BF) and pH was applied to control the pilot-scale SBR process. Results showed that short-cut nitrification process achieved within 50 days at low temperature (11-16 degrees C), and the nitrite accumulation rate (NAR) of SBR process increased from 19.8% to 90%. Short-cut nitrification process in pilot-scale SBR was maintained for as long as 550 days in the temperature range of 9-28 degrees C, and NAR was maintained above 95%. Meanwhile, the total nitrogen (TN) in effluent was 3 mg x L(-1) and the TN removal efficiency was above 95%. Therefore, it is feasible to start-up and maintain the short-cut advanced nitrogen removal process under low temperature condition in the SBR process.

Start up partial nitrification at low temperature with a real-time control strategy based on blower frequency and pH.

In this study, the performance of partial nitrification via nitrite at low temperature was investigated in a pilot-scale sequencing batch reactor (SBR) with a working volume of 7.0m(3). A novel real-time control strategy, based on blower frequency (BF) and pH, was designed and evaluated. The nitrogen break point (NBP) in the BF curve and the nitrate/nitrite apex point (NAP) in the pH curve were used to identify the endpoint of the aerobic and anoxic phases, respectively. The nitrite accumulation rate (NAR) rapidly increased from 19.8% to 90%. Partial nitrification was achieved at low temperature (11-16°C) in 40 days and was stably maintained for as long as 140 days by applying a real-time control strategy based on pH and BF. Fluorescence in situ hybirdization (FISH) results demonstrated that ammonia oxidation bacteria (AOB) had developed into the dominant nitrifying bacteria compared to nitrite oxidation bacteria (NOB) in the system.

[Optimization effect of nitrogen and phosphorus removal in unifed SBR process for domestic wastewater].

Appropriate change of the traditional operation modes was investigated in a UniFed SBR lab-scale apparatus treating actual domestic wastewater with low C/N and C/P. Results showed that when the feed/decant time was extended from 2 h to 3 h and 4 h, the phosphorous removal efficiency increased from 59.93% to 88.45% without any external carbon source. In the mode of anoxic-aerobic condition, TIN of the effluent reduced obviously, the removal efficiency increased from 49.54% to 60.75% for utilizing limited substrate in influents with low C/N = 2.57, adequately. In the mode of alternation of anoxic-aerobic condition, the nitrogen and phosphorous removal efficiency increased clearly. The carbon source in the influent can be used adequately and it occurred denitrifying dephosphatation in anoxic segment 2. This mode was optimal for the treatment of actual domestic wastewater with low C/N and C/P.

[Analysis and establishment of control modes of advanced nitrogen removal via nitrite in SBR].

To achieve stable advanced nitrogen removal via nitrite in SBR, factors influencing pH variation in treating real domestic wastewater were investigated. The characteristic points were found to be appeared obviously on pH profile at both ends of ammonia oxidization and denitrification by analyzing the mechanism of biological nitrogen removal and the balance of carbonic acid. Using pH as control parameter in SBR for treating domestic or municipal wastewater with low organic concentration and suitable alkalinity could achieve advanced nitrogen removal with effluent TN below 1 mg/L. Moreover, it could prevent the decrease of nitrite accumulation rate causing by excessive aeration, which plays an important role on the stability of advanced nitrogen removal via nitrite. Based on theoretical analysis and experimental study, the real-time control strategy of advanced nitrogen removal via nitrite was established. To accommodate the different water quality and retain the accuracy of control strategy, 18 adjustable variables were set up in control strategy. The control strategy established a foundation for developing control software and control system of advanced nitrogen removal via nitrite.