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L‐cysteine is an important sulfur‐containing amino acid being difficult to produce by microbial fermentation. Due to the lack of high‐throughput screening methods, existing genetically engineered bacteria have been developed by simply optimizing the expression of L‐cysteine‐related genes one by one. To overcome this limitation, in this study, a biosensor‐based approach for multilevel biosynthetic pathway optimization of L‐cysteine from the DecR regulator variant of Escherichia coli was applied. Through protein engineering, we obtained the DecRN29Y/C81E/M90Q/M99E variant‐based biosensor with improved specificity and an 8.71‐fold increase in dynamic range. Using the developed biosensor, we performed high‐throughput screening of the constructed promoter and RBS combination library, and successfully obtained the optimized strain, which resulted in a 6.29‐fold increase in L‐cysteine production. Molecular dynamics (MD) simulations and electrophoretic mobility shift analysis (EMSA) showed that the N29Y/C81E/M90Q/M99E variant had enhanced induction activity. This enhancement may be due to the increased binding of the variant to DNA in the presence of L‐cysteine, which enhances transcriptional activation. Overall, our biosensor‐based strategy provides a promising approach for optimizing biosynthetic pathways at multiple levels. The successful implementation of this strategy demonstrates its potential for screening improved recombinant strains. [ABSTRACT FROM AUTHOR]

Fe single‐atom catalysts (SACs) are a promising catalyst for oxygen reduction reaction (ORR) in both Zn–air batteries (ZABs) but have a certain distance to compete with Pt‐based catalysts. Rational modulation of the coordination environment in the second coordination shell of SACs offers an opportunity to improve the intrinsic ORR activity, yet a challenge. Here, a novel strategy is reported to construct a dual‐metal catalyst by introducing a single Co atom in the second coordination shell of the Fe center. The dual‐metal N3─Fe─N─Co site with a certain Fe─Co distance of 0.312 nm is constructed. It allows for manipulation of the positive shift of the Fe center charge state, driving the d‐band center up‐shift by 0.63 eV, thereby offering the optimal adsorption of intermediates. Benefiting from this structure, the as‐prepared Fe(Co2nd)‐NC enables an excellent ORR activity with a half‐wave potential of 0.948 V in 0.1 M KOH. As a cathode in ZABs, it delivered an outstanding peak power density of 218 mW cm−2 and a specific capacity of 915 mAh gZn−1 at 5 mA cm−2, respectively, with superior long‐term durability over 680 h. The second shell layer alignment regulation strategy shows great potential for energy storage applications. [ABSTRACT FROM AUTHOR]

Objective: Isolated intra‐articular anterior cruciate ligament (ACL) reconstruction is not capable of restoring instability in many cases leading some to recommend concomitant anterolateral ligament (ALL) reconstruction. The satisfactory fixation site and graft length change are crucial in ligament reconstruction to restore the ALL function and avoid some unwanted graft behavior. The purpose of this investigation is to determine the optimal isometric region on the anterolateral aspect of the knee for ALL reconstruction using a three‐dimensional optical instrument and a suture similar to an intraoperative isometric test. Methods: Six freshly frozen cadaveric human knees were used in this study. Data regarding the anterolateral surface were obtained using an optical measurement system to create a three‐dimensional model. Nine points were selected on the femur (F1‐F9) and tibia (Ta‐Ti) respectively. The three‐dimensional length change between each pair of tibial and femoral points was measured during passive knee flexion from 0° to 90° in 15° increments. Subsequently, five femoral points (A–E) were selected from the lateral femur, located in different areas relative to the lateral femoral epicondyle, and three tibial reference points (T1‐T3) were selected in the isometric test. The changes in the length between each pair of reference points were measured using sutures. The 95% confidence interval for the rate of length change was estimated using the mean and standard deviation of the maximum rate of length change at different flexion angles, and the data were expressed as the mean (95% confidence interval) and compared with the maximum acceptable rate of change (10%). Results: The maximum acceptable change rate for ligament reconstruction is 10%, and the mean maximum rates and the 95% confidence interval (CI) of length change for the point combinations were calculated. Among all the combined points measured using the optical measurement system and the suture, the qualified point combination for reconstruction was F3 (8mm posterior and 8mm proximal to the lateral femoral epicondyle)‐Tb (8mm proximal to the midpoint between the center of Gerdy's tubercle and the fibula head), A (posterior and proximal to the lateral femoral epicondyle)‐T2 (10mm below the joint line)and A‐T3 (15 mm below the joint line). The position of F3‐Tb and A‐T2 are close to each other. Conclusion: The most isometric area of the femur for ALL reconstruction was posterior and proximal to the lateral femoral epicondyle. We recommend that the initial location of the femoral point be set at 8 mm posterior and 8 mm proximal to the lateral femoral epicondyle and the tibial point at approximately 10 mm below the joint line, midway between Gerdy's tubercle and fibular head, and subsequently adjusted to the most satisfactory position according to the isometric test. [ABSTRACT FROM AUTHOR]