Main conclusionThe seed coat gene VviAGL11 coordinates with endosperm development genes FIS2, PHERESE1 and IKU2 and functions as the key regulator in seed development and abortion processes in grapevine.

Friction and wear tests were performed on five Cu-based materials and three polyether ether ketone (PEEK)-based composites sliding against 17-4PH and 42CrMo4 coated with tungsten carbide-reinforced Ni-based coating. Two types of pin-on-disk specimens were used to represent the slipper/eccentric drive and piston/sleeve gap seal tribo-pairs in water hydraulic radial piston pumps. The experimental results showed that the QSn8-0.3 slipper material exhibited the highest steady-state friction coefficients for sliding against both 17-4PH (0.156) and coated-42CrMo4 (0.894). Glass fiber-reinforced PEEK exhibited the highest steady-state friction coefficients for sliding against the two specimens (0.540 and 0.420). The ZCuPb15Sn8/17-4PH showed the highest wear rate for the representative slipper/eccentric drive tribo-pair (26.86  ×  10−6 mm/Nm); glass fiber-reinforced PEEK/17-4PH showed the highest wear rate for the representative piston/sleeve gap seal tribo-pair (46.91  ×  10−6mm/Nm). The wear mechanisms of the two types of tribo-pairs were characterized through scanning electron microscopy, profilometry, and energy-dispersive spectroscopy analyses. Furthermore, the effects of hardness, pv values, coating, and reinforcement on the tribological behavior of the two types of tribo-pairs were analyzed.

This paper aims to explore the influences of multilevel sinusoidal structures on clearance flow by using numerical and experimental methods. A hierarchical sinusoidal morphology was proposed to design the gap between matching surfaces in water hydraulic systems. The specimens with the 0 th order, the 1 st order and the 2 nd order sinusoidal structures were machined by a three dimensional (3D) printer, and their clearance leakage flow was tested on a water hydraulic annular clearance test rig. An extensive simulation study on the effects of waved surfaces with varying amplitudes and wavelengths on leakage was presented. Both the experimental and numerical results show that introducing hierarchical morphology on clearance surfaces will reduce leakage. Moreover, it was found that the leakage decreases with the increase of the ratio of the amplitude to wavelength. Further study of the flow field reveals that the leakage reduction of the 2 nd order sinusoidal model is obtained due to the extra vortexes of various scales and the narrower width of the main flow and lower velocity. Moreover, our results indicate that the waved surface induces a micro-hydrodynamic effect that creates an additional load carrying capability, which is helpful for separating the matching surfaces to reduce wear. The study is beneficial to investigate the potential for improving efficiency through the optimization of gap design.