Understanding of the functional significance of microRNAs (miRNAs) requires efficient and accurate detection method. In this study, we developed an improved miRNAs quantification system based on quantitative real-time polymerase chain reaction (qRT-PCR). This method showed higher efficiency and accuracy to survey the expression of primary miRNAs (pri-miRNAs), precursor miRNAs (pre-miRNAs), and mature miRNAs. Instead of relative quantification method, we quantified the pri-miRNAs and pre-miRNAs with absolute qRT-PCR based on SYBR Green I fluorescence. This improvement corrected for the inaccuracy caused by the differences in amplicon length and PCR efficiency. We also used SYBR Green method to quantify mature miRNAs based on the stem-loop qRT-PCR method. We extended the pairing part of the stem-loop reverse transcript (RT) primer from 6 to 11 bp, which greatly increased the efficiency of reverse transcription PCR (RT-PCR). The performance of the improved RT primer was tested using synthetic mature miRNAs and tissue RNA samples. Results showed that the improved RT primer demonstrated dynamic range of seven orders of magnitude and sensitivity of detection of hundreds of copies of miRNA molecules.

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In order to investigate the effects of chromium on the electrical contact properties of the Al2O3-Cu/15W composites, vacuum hot-pressing sintering and internal oxidation methods were employed to fabricate the Al2O3-Cu/15W and Al2O3-Cu/15W5Cr composites. The microstructure was analyzed by scanning and transmission electron microscopy. The electrical contacts testing was performed using the JF04C testing machine at 30 V DC with 10-30 A current. The effects of Cr on the comprehensive properties, arc erosion morphology and welding force of the electrical contacts were investigated. The mass transfer mechanism was discussed. It was demonstrated that the Al2O3 nanoparticles pinned dislocations. The diffraction spots of the Cu matrix and the γ-Al2O3 disclose an orientation relationship of <103>Cu//<103>γ−Al2O3,{020}Cu//{040}γ−Al2O3. A typical arc erosion morphology, such as needle-like and coral structures was formed, which provides significantly enhanced arc erosion resistance of the contact material. Compared with the Al2O3-Cu/15W composite, the Al2O3-Cu/15W5Cr composite has a lower welding force. The two composites present two distinct mass transfer trends before and after 25 A. The final mass transfer direction of the composites is from the cathode to the anode. The Al2O3-Cu/15W5Cr contacts have less mass change under all testing conditions.

Disturbances are widespread in biochemical systems. Nowadays, prevalent single-loop control strategies only take external disturbances into account. However, internal perturbations that threaten the stability of biochemical systems are invariably ignored. In this paper, a DNA strand displacement (DSD)based cascade PID control system is designed. In addition to traditionally realizing the tracking of reference input and the attenuation of primary disturbance, the presented control approach also innovatively completes the rejection of secondary disturbance. Specifically, the dynamics of the reference input signal are first governed by a first-order low-pass filter integrated with cascade PID control systems, which efficiently avoids the excessive response of the cascaded primary and secondary controllers to the reference signal. Then, cascade PID controllers and second-order time-delay plants are constructed by utilizing the chemical reaction network (CRN) and the DSD. In terms of secondary perturbation suppression, the obtained control scheme significantly outperforms the single-loop PID control scheme with a smaller overshoot and faster settling time. Finally, the DSD-based cascade PID control method is applied to regulate gene expressions of interferon regulatory factor 4 (IRF4) and interferon regulatory factor 5 (IRF5) that affect the polarization of tumorassociated macrophages (TAMs). Compared with the single-loop PID control strategy, the control strategy exhibits a better inhibitory effect on IRF5 gene overexpression (internal disturbance) and TAMs endogenous gene expression (external disturbance).INDEX TERMS Cascade PID control systems, chemical reaction networks, DNA strand displacement, secondary disturbance, regulation of tumor-associated macrophage polarization

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