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Objective To establish a rapid screening method for in vitro site-directed mutants or CRISPR/Cas9-mediated knock-in mutants, and to improve mutant screening efficiency and reduce experimental costs. Methods Polymerase chain reactions (PCRs) were carried out with primers designed with the last one, two, and three nucleotides in the 3' end matching the mutated DNA sequences for the constructed in vitro site-directed mutants or CRISPR/Cas9-mediated knock-in mutants, and agarose gel electrophoresis was used to detect specific amplification bands. Results PCR using specific mutation screening primers effectively amplified DNA bands in correct mutants but failed in unsuccessfully mutated samples. The presence of DNA amplification bands revealed by agarose gel electrophoresis confirmed the successful screening for desired mutants. Conclusion The rapid screening method for mutants introduced in this study can easily and quickly identify correct mutants, which significantly simplifies the identification process of mutations, and thereby reduces experimental costs and improves work efficiency.

In response to the increasing demand for mobile communication traffic, the user access point (AP) selection and downlink power control is used to improve the users experience of the cell-free (CF) massive multiple input multiple output (MIMO) system. Based on the maximum signal interference plus noise ratio, an effective subset of service APs is selected for each user. Based on the result of the AP selection, aiming at providing different quality-of-service (QoS) to users with different priorities, a long-term power constraint optimization model of downlink weighted power control is established. The problem is transformed into a convex optimization problem. By solving this problem, a set of optimized downlink power control coefficients is obtained. The algorithm is verified by simulation, which can increase the spectral efficiency of 95% users of the CF massive MIMO system by about 11 times. At the same time, it helps to effectively improve the experience of high-priority users. It has certain significance for the study of the CF massive MIMO system. [ABSTRACT FROM AUTHOR]

Objective: To investigate the clinical results of treating leg open fracture with soft tissue defect by pedicle flap transfer in combination with external fixator., Methods: From May 2004 to June 2007, 12 cases of leg open fracture with soft tissue defect, 9 males and 3 females aged 18-75 years, were treated. Among them, 8 cases were caused by traffic accidents, 2 crush, 1 falling and 1 mechanical accident. According to the Gustilo Classification, there were 2 cases of type II, 5 of type IIIA and 5 of type IIIB. There were 2 cases of upper-tibia fracture, 3 of middle-tibia and 7 of middle-lower. The sizes of soft tissue defect ranged from 5 cm x 3 cm to 22 cm x 10 cm.The sizes of exposed bone ranged from 3 cm x 2 cm to 6 cm x 3 cm. The course of the disease was 1-12 hours. Fracture fixation was reached by external fixators or external fixators and limited internal fixation with Kirschner wire. The wounds with exposed tendons and bones were repaired by ipsilateral local rotation flap, sural neurocutaneous flap and saphenous nerve flap. The size of selected flap ranged from 5 cm x 4 cm to 18 cm x 12 cm. Granulation wounds were repaired by skin grafting or direct suture., Results: All patients were followed up for 6 months to 2 years. All patients survived, among whom 2 with the wound edge infection and 1 with the distal necrosis were cured by changing the dressing, 8 with pin hole infection were treated by taking out the external fixator, 1 with nonunion received fracture healing after bone graft in comminuted fracture of lower tibia, 2 suffered delayed union in middle-lower tibia fracture. The ROM of ankle in 3 cases was mildly poor with surpass-joint fixation, with plantar extension of 0-10 degrees and plantar flexion of 10-30 degrees, while the others had plantar extension of 10-20 degrees and plantar flexion of 30-50 degrees., Conclusion: The method of pedicle flap transfer combined with external fixator is safe and effective for the leg open fracture with soft tissue defect.