Crystal structure and Hirshfeld surface analysis of 3-methyl-4-oxo-N-phenyl-3,4-dihydroquinazoline-2-carbothioamide

The asymmetric unit of the title compound, C16H13N3OS, comprises two molecules (A and B) with similar conformations that differ mainly in the orientation of the phenyl group relative to the rest of the molecule, as expressed by the Cthioamide—Nthioamide—Cphenyl—Cphenyl torsion angle of 49.3 (3)° for molecule A and of 5.4 (3)° for molecule B. In the crystal, two intermolecular N—H...N hydrogen bonds lead to the formation of a dimer with R 2 2(10) graph-set notation. A Hirshfeld surface analysis revealed that H...H interactions are the most important intermolecular interactions, contributing 40.9% to the Hirshfeld surface.

Modeling and experimental investigation of magnetically coupling bending-torsion piezoelectric energy harvester based on vortex-induced vibration

This paper presents a magnetically coupling bending-torsion piezoelectric energy harvester based on vortex-induced vibration from low-speed wind. The theoretical model of the energy harvester was formulated and validated by wind tunnel experiments. Numerical and experimental results showed that the power output and bandwidth of the proposed harvester are improved about 180% and 230% respectively compared with the nonmagnetic coupling harvester. Furthermore, the effects of cylinder, piezoelectric layer, load resistance, and magnetic nonlinear parameters on the harvester were investigated based on the distributed parameter model. The results showed that the length of cylinder hardly affect output power, but the diameter of cylinder presented complicated influences. The width of piezoelectric beam was negatively correlated with the torsion angle. With increasing the length of piezoelectric layer, an optimal wind velocity and load resistance can be obtained for the maximum output power. With decreasing of the distance between two magnets, the resonant bandwidth, the optimal power output, and torsion angle can be enhanced, respectively. Besides, the magnetic potential energy increased owing to the magnetically coupling, which led to the improvement of onset speed for the energy harvester. This study provides a guideline on improving the performance of bending-torsion vibration piezoelectric energy harvester.

Effects of Contact Load and Torsion Angle on Crack Propagation Behaviors of Inclined Crossed Steel Wires during Tension–Torsion Fretting Fatigue in Acid Solution

The hoisting rope in the kilometer-deep coal mine exhibits the tension–torsion fretting fatigue behaviors of inclined crossed steel wires in acid solution. Distinct contact load and torsion angles of steel wires in the rope cause different crack propagation behaviors, which greatly affect the fatigue lives of steel wires. Therefore, the effects of contact load and torsion angle on the crack propagation behaviors of inclined crossed steel wires during tension–torsion fretting fatigue in acid solution were investigated in the present study. The three-dimensional X-ray tomographic micro-imaging system was used to reveal evolutions of crack profiles and crack propagation depths during the test. The evolution of friction coefficient between steel wires during the test is presented. The three-dimensional white light interference microscope, electrochemical analyzer, and scanning electron microscope were employed to investigate the wear depth profiles, Tafel polarization curves and impedance spectra, and wear scar morphologies, respectively, of steel wires. Effects of contact load and torsion angle on crack propagation behaviors of inclined crossed steel wires during the tests were explored through analyses of friction and wear mechanisms and electrochemical corrosion damage. The results show that as the contact load and torsion angle increase, the crack propagation depth and rate of steel wire both increase and the fatigue life of steel wire decreases. Those are mainly attributed to the increases in the average tangential force between steel wires, wear depth, electrochemical corrosion tendency, and surface damage of steel wire as well as the decrease in corrosion resistance.

Numerical simulation of an electroosmotic micromixer with variable modules

We designed a new type of [Formula: see text]-type electroosmotic micromixer with variable modules (EMVMs). By applying 7V alternating current (AC) voltage to the EMVM, the mixing efficiency at different Reynolds number (Re) is discussed by changing the rotation angles of modules at different positions in different directions. We found that the mixing efficiency of the EMVM can reach 99% when the first block is rotated along the xz-axis. Then, we change the torsion angle of the same variable module and find that the mixing efficiency can reach 99.3% when the torsion is [Formula: see text]. Finally, we change the voltage value and find that the mixing efficiency of the EMVM increases with the increase of voltage values.

Field Study on Deformation and Stress Characteristics of Large Open Caisson during Excavation in Deep Marine Soft Clay

Oujiang River North Estuary Bridge in Wenzhou is the world’s first double-deck suspension bridge under construction with three-tower and four-span. It is the first time to build large open caisson foundation in the deep marine soft clay in estuary with strong tide, extending the application scope of caisson. To study the deformation and stress characteristics of large open caisson during excavation and ensure the safety of anchorage excavation, a large number of sensors are arranged in the caisson. By analyzing the change of tip resistance, lateral soil pressure, and posture parameters during caisson excavation, the stress characteristics and deformation of caisson are described. The result shows the following. (1) Because of the thixotropy of soft clay, the reaction force of partition wall in deep soft soil area of caisson is similar to that of blade foot, and the reaction force of blade foot can be effectively reduced through the layering construction of caisson. (2) The height of caisson construction and the sand-bearing stratum will obviously affect the plane torsion angle of caisson. When the caisson enters the sand-bearing stratum, the lateral soil pressure increases significantly, which leads to the increase of the plane torsion angle. (3) The inclination and central deviation of caisson are sensitive to the caisson construction and stratum property. It can be found that the lateral soil pressure, plane torsion angle, inclination, and central deviation of caisson are sensitive to stratum property, and inhomogeneity of stratum easily leads to inclination of caisson. Based on the field monitoring data, the stress characteristics and geometric posture of caisson during sinking are studied, which provide technical guidance for scheme design and subsidence prediction analysis of caisson in deep marine soft clay. It can provide a good opportunity to study the behaviors of large caisson foundation constructed in deep marine soft clay and has great significance and reference value for construction optimization of anchorage structure.

Tension-Torsion Fatigue Tests on the proton Exchange membrane Nafion 115, used in fuel cells

Fatigue tests under tension-torsion have been carried out on the membrane Nafion 115 (Perfluorosulfonic acid, PFSA). This polymeric material is a main component to construct fuel cells, used as proton exchange membrane. These membranes undergo mechanical loading of tension and torsion during its industrial life. A self-designed machine has been constructed to obtain the fatigue endurance on this polymeric material under tension-torsion and the following conditions: one magnitude for the torsion angle, five initial tensile stresses, room temperature, and environmental relative humidity, and frequency of 1.6 Hz. The experimental results show that fatigue endurance decreases with the increase of tensile stress when the torsion angle remains constant, as well as temperature and relative humidity (both taken at environmental conditions). Fracture surfaces were analyzed by SEM, in order to investigate the principal trends of crack initiation and propagation under this modality of fatigue loading. Se han realizado ensayos de fatiga bajo tensión-torsión en la membrana Nafion 115 (ácido perfluorosulfónico, PFSA). Este material polimérico es un componente principal para la construcción de pilas de combustible, utilizado como membrana de intercambio de protones. Estas membranas se someten a cargas mecánicas de tensión y torsión durante su vida industrial. Se ha construido una máquina de diseño propio para obtener la resistencia a la fatiga de este material polimérico bajo tensión-torsión y en las siguientes condiciones: una magnitud para el ángulo de torsión, cinco tensiones iniciales de tracción, temperatura ambiente y humedad relativa ambiental, y frecuencia de 1,6 Hz. Los resultados experimentales muestran que la resistencia a la fatiga disminuye con el aumento de la tensión de tracción cuando el ángulo de torsión se mantiene constante, así como la temperatura y la humedad relativa (ambas tomadas en condiciones ambientales). Las superficies de fractura fueron analizadas por SEM, con el fin de investigar las principales tendencias de iniciación y propagación de grietas bajo esta modalidad de carga de fatiga.

The Effects of Modified Graded Recession, Anteriorization and Myectomy of Inferior Oblique Muscles on Superior Oblique Muscle Palsy

Background: The aim was to investigate the effect of inferior oblique (IO) operation (IO myectomy or graded recession and anteriorization) for unilateral and bilateral superior oblique muscle palsy (SOP); Methods: A total of 167 eyes undergoing IO surgery by a single surgeon between 2008 and 2015 were retrospectively reviewed. The method for treating symmetric bilateral SOP was bilateral IO myectomy (n = 102) and the method for treating unilateral SOP or non-symmetric bilateral SOP was IO-graded recession and anteriorization (n = 65). Associated clinical results and other factors were analyzed; Results: Head tilt, vertical deviation, IO overaction, SO underaction degree and ocular torsion angle were all clearly changed, but there was no statistically significance between these two procedures. Mean preoperative torsional angle was 15.3 ± 6.4 degree, which decreased to 5.3 ± 2.7 degree after surgery. Preoperative torsional angle, IOOA and SOUA degree were all significantly affected in postoperative torsional angle (p = 0.025, 0.003 and 0.038). Horizontal rectus muscle and IO muscle operation did not interfere with each other’s results (p = 0.98); Conclusions: Symmetric bilateral SOP could be treated with bilateral IO myectomy and IO-graded recession and anteriorization should be reserved for unilateral SOP or non-symmetric bilateral SOP.

Femoral Periprosthetic Fracture Treatment Using the Ortho-Bridge System: A Biomechanical Study

Background: We undertook a comparative biomechanical study of type B1 fractures around the femoral prosthesis following cemented hip arthroplasty using the Ortho-Bridge System (OBS) and a locking compression plate/locking attachment plate structure (LCP+LAP), and aimed to determine the effectiveness and advantages of the OBS when treating this fracture type. Methods: An OBS fixation model was designed based on OBS and LCP+LAP fixation characteristics. The LCP+LAP combination (Group A) and three different OBS combinations (Groups B, C, and D) were used to fix a B1 fracture model with a femoral periprosthetic fracture. Axial compression and torsion experiments were then performed using simple and comminuted fracture models. We conducted axial compression failure, model stiffness, and torsion angle tests, and tested the vertical load of final failure. Results: When simulating simple oblique fractures, no significant difference was found in terms of stiffness between the four groups in the axial compression experiment (P = 0.257). The torsion angle of the LCP+LAP system was significantly higher than that of the OBS (P < 0.05); however, there was no significant difference in the torsion angle between the OBS combinations (P > 0.05). Axial compression experimental data showed that stiffness in the three OBS combinations was higher than that in the LCP+LAP system (P = 0.000). Torsion angles of the three OBS combinations were smaller than those of the LCP+LAP system (P < 0.05). In the axial compression failure test, the fixed failure mode in the LCP+LAP system involved destruction of the contact cortex at the fracture site, while the failure modes in the three OBS combinations involved destruction of the contact cortex at the fracture site and the fracture around the screws above the osteotomy. Conclusion: Compared with the LCP+LAP, the OBS showed superior biomechanical results. Furthermore, the OBS has the advantage of multiple choices and high flexibility of combinations. Stress dispersion was helpful in avoiding internal fixation failure during early postoperative functional exercise.