The Study of Comprehensive Reinforcement Mechanism of Hexagonal Boron Nitride on Concrete

The addition of hexagonal boron nitride (h-BN) has introduced a comprehensive reinforcing effect to the mechanical and electrochemical properties of commercial concrete, including fiber reinforced concrete (FRC) and steel fiber reinforced concrete (SFRC). Although this has been proven effective and applicable, further investigation and study is still required to optimize the strengthen result which will involve the exfoliation of h-BN into single-layered nano sheet, improving the degree of dispersion and dispersion uniformity of h-BN into concrete matrix. There is currently no direct method to test the degree of dispersion of non-conductive particles, including h-BN, in concrete matrix, therefore it is necessary to obtain an analogous quantification method like SEM, etc. The reinforcing mechanism on concrete, including FRC and SFRC is now attracting a great number of interest thanks to the huge potential of application and vast demand across the world. This study briefly describes the reinforcing mechanism brought by h-BN. In this study, different samples under varied conditions were prepared according to the addition of h-BN and dispersant to build a parallel comparison. Characterization is mainly focused on their mechanical properties, corrosive performance and SEM analysis of the cross-section of post-failure samples

Three-Dimensional Flight Conflict Detection and Resolution Based on Particle Swarm Optimization

This paper presents a conflict detection and resolution method based on a velocity obstacle method for flight conflicts in a three-dimensional space. With the location and speed information of the two aircraft, the optimal relief strategy is obtained using particle swarm optimization. Aiming at the problem of excessive computational complexity in solving flight conflicts in a three-dimensional space with a cylindrical flight protection zone, an improved method for narrowing the search range is proposed to achieve a rapid solution by simplifying the complicated three-dimensional problem into a two-dimensional problem. The generality and flexibility of the method is effectively verified through simulations in flight conflict scenarios which almost cover all common situations. The experimental results show that the method can accurately determine the conflict time and generate the optimal relief strategy for different scenarios. The improved method of optimizing-search-range can significantly improve the computational efficiency, taking about 0.4 s to find the optimal solution, which can be used in real-time conflict resolution. The study provides a new solution for the flight conflict resolution problem

Heparin induces α-synuclein to form new fibril polymorphs with attenuated neuropathology

The Cryo-EM structures reported in this work reveal how heparin incorporates into α-syn fibril formation to determine fibril polymorphs. This highlights the role of biological polymers in the conformational selection and neuropathological regulation of amyloid fibrils

Data_Sheet_1_Mechanistic and biophysical characterization of polymyxin resistance response regulator PmrA in Acinetobacter baumannii.pdf

IntroductionAcinetobacter baumannii PmrAB is a crucial two-component regulatory system (TCS) that plays a vital role in conferring resistance to polymyxin. PmrA, a response regulator belonging to the OmpR/PhoB family, is composed of a C-terminal DNA-binding effector domain and an N-terminal receiver domain. The receiver domain can be phosphorylated by PmrB, a transmembrane sensor histidine kinase that interacts with PmrA. Once phosphorylated, PmrA undergoes a conformational change, resulting in the formation of a symmetric dimer in the receiver domain. This conformational change facilitates the recognition of promoter DNA by the DNA-binding domain of PmrA, leading to the activation of adaptive responses.MethodsX-ray crystallography was carried out to solve the structure of PmrA receiver domain. Electrophoretic mobility shift assay and Isothermal titration calorimetry were recruited to validate the interaction between the recombinant PmrA protein and target DNA. Field-emission scanning electron microscopy (FE-SEM) was employed to characterize the surface morphology of A. baumannii in both the PmrA knockout and mutation strains.ResultsThe receiver domain of PmrA follows the canonical α5β5 response regulator assembly, which undergoes dimerization upon phosphorylation and activation. Beryllium trifluoride is utilized as an aspartate phosphorylation mimic in this process. Mutations involved in phosphorylation and dimerization significantly affected the expression of downstream pmrC and naxD genes. This impact resulted in an enhanced cell surface smoothness with fewer modifications, ultimately contributing to a decrease in colistin (polymyxin E) and polymyxin B resistance. Additionally, a conservative direct-repeat DNA PmrA binding sequence TTTAAGNNNNNTTTAAG was identified at the promoter region of the pmrC and naxD gene. These findings provide structural insights into the PmrA receiver domain and reveal the mechanism of polymyxin resistance, suggesting that PmrA could be a potential drug target to reverse polymyxin resistance in Acinetobacter baumannii.</p