4-(4-Fluoro­phen­yl)-2-oxo-1,2,5,6-tetra­hydro­benzo[h]quinoline-3-carbonitrile

In the mol­ecule of the title compound, C20H13FN2O, the fluoro­phenyl ring is oriented at a dihedral angle of 72.76 (3)° with respect to the fused benzene ring. In the crystal structure, inter­molecular N—H⋯O, C—H⋯O and C—H⋯F inter­actions link the mol­ecules into chains. π–π contacts between the quinoline and benzene rings [centroid–centroid distance = 3.918 (3) Å] may further stabilize the structure. A weak C—H⋯π inter­action is also present. The O atom and two of the CH2 groups of the quinoline ring system are disordered over two positions. The O atom was refined with occupancies of 0.489 (17) and 0.511 (17), while C and H atoms were refined with occupancies of 0.435 (13) and 0.565 (13)

2-Amino-4-(4-chloro­phen­yl)-6-ferro­cenylpyridine-3-carbonitrile

In the mol­ecule of the title compound, [Fe(C5H5)(C17H11ClN3)], the dihedral angles between the two five–membered rings and between the two six-membered rings are 3.28 (4) and 51.33 (4)°, respectively. In the crystal structure, inter­molecular N—H⋯N hydrogen bonds link the mol­ecules into centrosymmetric dimers

Chaperone Spy Protects Outer Membrane Proteins from Folding Stress via Dynamic Complex Formation

Gram-negative bacteria have a multicomponent and constitutively active periplasmic chaperone system to ensure the quality control of their outer membrane proteins (OMPs). Recently, OMPs have been identified as a new class of vulnerable targets for antibiotic development, and therefore a comprehensive understanding of OMP quality control network components will be critical for discovering antimicrobials. Here, we demonstrate that the periplasmic chaperone Spy protects certain OMPs against protein-unfolding stress and can functionally compensate for other periplasmic chaperones, namely Skp and FkpA, in the Escherichia coli K-12 MG1655 strain. After extensive; in vivo; genetic experiments for functional characterization of Spy, we use nuclear magnetic resonance and circular dichroism spectroscopy to elucidate the mechanism by which Spy binds and folds two different OMPs. Along with holding OMP substrates in a dynamic conformational ensemble, Spy binding enables OmpX to form a partially folded β-strand secondary structure. The bound OMP experiences temperature-dependent conformational exchange within the chaperone, pointing to a multitude of local dynamics. Our findings thus deepen the understanding of functional compensation among periplasmic chaperones during OMP biogenesis and will promote the development of innovative antimicrobials against pathogenic Gram-negative bacteria.; IMPORTANCE; Outer membrane proteins (OMPs) play critical roles in bacterial pathogenicity and provide a new niche for antibiotic development. A comprehensive understanding of the OMP quality control network will strongly impact antimicrobial discovery. Here, we systematically demonstrate that the periplasmic chaperone Spy has a role in maintaining the homeostasis of certain OMPs. Remarkably, Spy utilizes a unique chaperone mechanism to bind OmpX and allows it to form a partially folded β-strand secondary structure in a dynamic exchange of conformations. This mechanism differs from that of other E. coli periplasmic chaperones such as Skp and SurA, both of which maintain OMPs in disordered conformations. Our study thus deepens the understanding of the complex OMP quality control system and highlights the differences in the mechanisms of ATP-independent chaperones

Research on Steering Stability Control Strategy of Four-wheel Independent Electric Drive Special Vehicles

In order to solve the steering stability problem of a special four-wheel independent electric vehicle, a dynamic model of the vehicle was established to analyze the cause of vehicle instability. A steering stability controller was designed, which included the upper yaw moment controller and the lower driving force distribution controller. Based on the sliding mode control algorithm, the yaw moment controller determines the yaw moment required while the vehicle is moving by controlling the yaw rate and sideslip angle. Based on the safety distribution method, the driving force distribution controller selects the sum of tire utilization rate as the optimization function to realize the optimal distribution of yaw moment. Software of MATLAB/Simulink and CarSim were used to build a co-simulation platform, and the designed steering stability controller was analyzed and verified. The simulation results show that the steering stability controller is helpful to improve the steering ability and handling stability of the vehicle in the extreme working conditions

Simulation Study on the Effects of DC Electric Field on Insulator Surface Pollution Deposit

Energized insulator’s surface contamination is greatly affected by its electric field properties. However, few reports about the electric field influencing mechanism on the pollution deposition have been presented. In this paper, the coupling-physics model of a three-unit XP-160 insulator string was established, and the particles’ deposition process was simulated by using the finite element method. The effects of the electric field on the pollution particles’ motion were analyzed. Research results indicate that the closer to the insulator string, the larger the intersection angle θ between the electric force and its horizontal component. The main function of the electric field on insulator contamination is that it changes the pollution particles’ vertical moving speed, thus accelerating the particles’ deposition process. The particle capture coefficient ratio ck can be used to reflect the pollution degree discrepancy between DC-energized and non-energized insulators. In this paper the ratio ck of the DC-energized to non-energized condition is in the range of 1.04 to 1.98, very close to the field measurement results of the DC pollution ratio k

Influence of hydrophobicity on ice accumulation process under sleet and wind conditions

Glaze, the most dangerous ice type in natural environment, forms during sleet weather, which is usually accompanied with wind. The icing performance of hydrophobic coatings under the impact of wind needs further research. This paper studies the influence of hydrophobicity on ice accumulation process under sleet and wind conditions by computer simulations and icing tests. The results indicate that the heat dissipation process of droplets on samples with various hydrophobicity will be accelerated by wind significantly and that a higher hydrophobicity cannot reduce the cooling rate effectively. However, on different hydrophobic surfaces, the ice accumulation process has different characteristics. On a hydrophilic surface, the falling droplets form continuously water film, which will be cooled fast. On superhydrophobic surface, the frozen droplets form ice bulges, which can shield from wind and slow down the heat dissipation process. These ice accumulation characteristics lead to the difference in ice morphology and make a higher hydrophobic surface to have a lower ice mass growth rate in long period icing tests. As a conclusion, superhydrophobic coating remain icephobic under wind and sleet conditions

Model for Predicting DC Flashover Voltage of Pre-Contaminated and Ice-Covered Long Insulator Strings under Low Air Pressure

In the current study, a multi-arc predicting model for DC critical flashover voltage of iced and pre-contaminated long insulator strings under low atmospheric pressure is developed. The model is composed of a series of different polarity surface arcs, icicle-icicle air gap arcs, and residual layer resistance. The calculation method of the residual resistance of the ice layer under DC multi-arc condition is established. To validate the model, 7-unit and 15-unit insulator strings were tested in a multi-function artificial climate chamber under the coexistent conditions of low air pressure, pollution, and icing. The test results showed that the values calculated by the model satisfactorily agreed with those experimentally measured, with the errors within the range of 10%, validating the rationality of the model

DC Flashover Performance of Various Types of Ice-Covered Insulator Strings under Low Air Pressure

In this study, icing flashover performance tests of typical DC porcelain, glass, and composite insulators are systematically carried out in a multifunction artificial climate chamber. The DC icing flashover voltages of seven typical insulators under various conditions of icing thickness, pollution severity before icing, string length, and atmospheric pressure are obtained. The relationships between icing thickness, salt deposit density as well as atmospheric pressure and the 50% icing flashover voltage are analyzed, and the formulas are obtained by regression method. In addition, the DC icing flashover voltage correction method of typical porcelain, glass, and composite insulator in the coexisting condition of high altitude, contamination, and icing is proposed

An S-Transform and Support Vector Machine (SVM)-Based Online Method for Diagnosing Broken Strands in Transmission Lines

During their long-term outdoor field service, overhead transmission lines will be exposed to strikes by lightning, corrosion by chemical contaminants, ice-shedding, wind vibration of conductors, line galloping, external destructive forces and so on, which will generally cause a series of latent faults such as aluminum strand fracture. This may lead to broken transmission lines which will have a very strong impact on the safe operation of power grids that if the latent faults cannot be recognized and fixed as soon as possible. The detection of broken strands in transmission lines using inspection robots equipped with suitable detectors is a method with good prospects. In this paper, a method for detecting broken strands in transmission lines using an eddy current transducer (ECT) carried by a robot is developed, and an approach for identifying broken strands in transmission lines based on an S-transform is proposed. The proposed approach utilizes the S-transform to extract the module and phase information at each frequency point from detection signals. Through module phase and comparison, the characteristic frequency points are ascertained, and the fault information of the detection signal is constructed. The degree of confidence of broken strand identification is defined by the Shannon fuzzy entropy (SFE-BSICD). The proposed approach combines module information while utilizing phase information, SFE-BSICD, and the energy, so the reliability is greatly improved. These characteristic qualities of broken strands in transmission lines are used as the input of a multi-classification SVM, allowing the number of broken strands to be determined. Through experimental field verification, it can be shown that the proposed approach displays high accuracy and the SFE-BSICD is defined reasonably