On fracture behavior of inner enamel:a numerical study

The ingenious hierarchical structure of enamel composed of rods and protein produces excellent fracture resistance.However,the fracture resistance mechanism in the inner enamel is unknown.The micromechanical models of enamel are constructed to numerically analyze the mechanical behaviors of the inner enamel with different decussation angles and different decussation planes.The results show that the manner of crack propagation in the inner enamel,including crack bridging,crack deflection,and crack bifurcation,is determined by both the rod decussation angle and the decussation plane.In the case of the strong decussation plane,the fracture strength and the required energy dissipation with the decussation angles of 15°and 30°are much higher than those without decussation,demonstrating that decussation is an important mechanism in improving the fracture resistance of enamel.The maximum tensile stress of enamel with the decussation angle of 15°is slightly higher than that of enamel with the decussation angle of 30°,illustrating that an optimal decussation angle exists which balances the strength and toughness.The synergetic mechanism of the decussation angle and the decussation plane on the crack propagation provides a new design hint for bionic composites.

Study on Spatial Variability of Soil Infiltration Coefficient in the Plain of the Yili River Valley in Xinjiang

22 typical test points and 8 profiles were selected and arranged in the plain of Yili River Valley based on lithological distribution and sedimentary characteristics to study spatial variability of soil infiltration coefficient. The results show that the infiltration coefficient of different geo-morphic units is as follows: the desert area > the pre-mountain alluvial-proluvial plain > river terrace,which is mainly related to the lithology of aeration zone,buried depth of groundwater and underlying surface. For the infiltration coefficient of different aeration zone mediums,the results are consistent with the changing law. The partition of plain of the Yili River Valley is based on geo-morphic units,infiltration coefficient and the lithology of aeration zone. The maximum infiltration coefficient is concentrated in the desert area,and there is zonal distribution of infiltration coefficient in plane.

Frequency-domain analysis of fluid-structure interaction in aircraft hydraulic pipeline systems: numerical and experimental studies

The fluid-structure interaction(FSI)in aircraft hydraulic pipeline systems is of great concern because of the damage it causes.To accurately predict the vibration characteristic of long hydraulic pipelines with curved segments,we studied the frequency-domain modeling and solution method for FSI in these pipeline systems.Fourteen partial differential equations(PDEs)are utilized to model the pipeline FSI,considering both frequency-dependent friction and bending-flexibility modification.To address the numerical instability encountered by the traditional transfer matrix method(TMM)in solving relatively complex pipelines,an improved TMM is proposed for solving the PDEs in the frequency domain,based on the matrix-stacking strategy and matrix representation of boundary conditions.The proposed FSI model and improved solution method are validated by numerical cases and experiments.An experimental rig of a practical hydraulic system,consisting of an aircraft engine-driven pump,a Z-shaped aero-hydraulic pipeline,and a throttle valve,was constructed for testing.The magnitude ratio of acceleration to pressure is introduced to evaluate the theoretical and experimental results,which indicate that the proposed model and solution method are effective in practical applications.The methodology presented in this paper can be used as an efficient approach for the vibrational design of aircraft hydraulic pipeline systems.

A YAP/TAZ-CD54 axis is required for CXCR2-CD44-tumor-specific neutrophils to suppress gastric cancer

As an important part of tumor microenvironment,neutrophils are poorly understood due to their spatiotemporal heterogeneity in tumorigenesis.Here we defined,at single-cell resolution,CD44-CxCR2-neutrophils as tumor-specific neutrophils(tsNeus)in both mouse and human gastric cancer(GC).We uncovered a Hippo regulon in neutrophils with unique YAP signature genes(e.g.,ICAM1,CD14,EGR1)distinct from those identified in epithelial and/or cancer cells.Importantly,knockout of YAP/TAz in neutrophils impaired their differentiation into CD54+tsNeus and reduced their antitumor activity,leading to accelerated GC progression.Moreover,the relative amounts of CD54+tsNeus were found to be negatively associated with GC progression and positively associated with patient survival.Interestingly,GC patients receiving neoadjuvant chemotherapy had increased numbers of CD54+tsNeus.Furthermore,pharmacologically enhancing YAP activity selectively activated neutrophils to suppress refractory GC,with no significant inflammation-related side effects.Thus,our work characterized tumor-specific neutrophils in GC and revealed an essential role of YAP/TAZ-CD54 axis in tsNeus,opening a new possibility to develop neutrophil-based antitumor therapeutics.