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Jianhong Li,1 Yingna Liang2 1Department of Radiology, Foshan Hospital of Traditional Chinese Medicine, Foshan, People’s Republic of China; 2Department of Gynaecology and Obstetrics, Guangzhou Baiyun First People’s Hospital (Baiyun District Maternal and Child Health Hospital), Guangzhou, Guangdong Province, People’s Republic of ChinaCorrespondence: Yingna Liang, Department of Gynaecology and Obstetrics, Guangzhou Baiyun First People’s Hospital (Baiyun District Maternal and Child Health Hospital), Guangzhou, Guangdong Province, People’s Republic of China, Email liangyn123@126.comObjective: In this study, it was intended to explore the causal association between mean platelet volume (MPV) and risk of deep vein thrombosis (DVT) using a two-sample Mendelian randomization (MR) analysis and a retrospective study.Methods: This study applied two-sample MR analysis to estimate the causal association between MPV and risk of DVT. Twenty-one single nucleotide polymorphisms (SNPs) were selected as genetic variants from two independent consortiums cohorts (p-value < 5× 10− 8, linkage disequilibrium r2< 0.1). Inverse variance weighted (IVW), MR-egger method and weighted median were performed. A retrospective study was also conducted to verify the associations identified from the MR study.Results: The MR analysis demonstrated that genetically predicted higher MPV was associated with significantly lower risk of DVT (OR 0.982, 95% CI = 0.967– 0.998, P = 0.023), with the consistent result in weighted median and MR-Egger. There was no directional horizontal pleiotropy in the method of MR-Egger regression (intercept=2.9e-04, P = 0.194). There was no single SNP was found to strongly drive the combined causal effect in the leave-one-out sensitivity analysis. Additionally, the similar result was observed in the retrospective study.Conclusion: This study suggested that MPV was negatively associated with the risk of DVT. More basic researches are needed in the future to explore its specific mechanism.Keywords: mean platelet volume, deep vein thrombosis, Mendelian randomization, causal association

Magnetic liquid double suspension bearing (MLDSB) includes electromagnetic system and hydrostatic system, and the bearing capacity and stiffness can be greatly improved. It is very suitable for the occasions of medium speed, heavy load, and starting frequently. Due to the mutual coupling and interaction between electromagnetic system and hydrostatic system, the probability and degree of static bifurcation are greatly increased and the operation stability is reduced. And flow of bearing cavity, coil current, oil film thickness, and galvanized layer thickness are the key parameters to ensure operation safe and stable, which has an important influence on the static bifurcation behavior. So this article intends to establish the coupling model of MLDSB to reveal the range of parameter combination in the case of static bifurcation. The influences of different parameter groups on the singularity characteristics, phase trajectory, x − t curves, and suction basin of the single DOF bearing system are analyzed. The result shows that there are nonzero singularities and static bifurcation occurs when ε 2 > 0 or δ 2 > 0 . As the flow of bearing cavity, coil current, oil film thickness, and galvanized layer thickness changes in turn, the singularities will convert between stable focus, unstable focus, stable node, and saddle point, and then the stable limit cycle may be generated. The attractiveness of singularity will change greatly with the flow of the bearing cavity and coil current changes slightly in the case of small current or large flow. The minimal change of galvanized layer thickness will lead to the fundamental change of the final stable equilibrium point of the rotor, while the final equilibrium point is slightly affected by the oil film thickness. This study can provide a reference for the supporting stability of MLDSB.

The droplet dynamic behavior of spraying during the manufacturing process affects tool life, cooling, and lubrication. A detailed understanding of droplet dynamic behavior is required to improve the surface quality while reducing the cutting fluid consumption. In this study, quantitative measurements for droplet diameter, number concentration, and axial velocity were carried out through a phase Doppler particle analyzer technique. The droplet characteristic spatial distributions of a standard twin-fluid nozzle (STN) and a novel twin-fluid nozzle (NTN) under different gas-to-liquid mass ratio (GLR) values were analyzed in detail. The results showed that the high-speed internal gas flow of an atomizing core has a significant effect on improving the synergistically enhanced atomization behavior, and more smaller droplets and an increased droplet momentum are easily obtained. Furthermore, a better spatial distribution of atomization characteristics can be achieved under a higher GLR of 4.3%. Furthermore, the effects of the novel atomizing core structural parameters on the droplet mean velocity spatial distribution, droplet turbulence, and root mean square velocity fluctuation were investigated. The results also showed that the improved NTN can effectively improve the spray atomization performance and droplet dynamic characteristics. In addition, comparative studies of the effect of the atomizing core structure on the machining performance were performed. Compared with the STN, the improved NTN achieves a significant reduction in cutting temperature, tool wear, and surface roughness of 17.25%, 33.96%, and 37.83%, respectively, owing to the better droplet dynamic characteristics and spatial distribution of spray atomization characteristics.

This work improves the tribological behavior via innovative surface designs for slipper pairs in seawater axial piston pumps. 316L stainless steel and carbon fiber/polyether ether ketone (CF/PEEK) ...

In this work, the lubrication mechanism and friction-wear characteristics of the friction pair between carbon-fiber-reinforced polyether ether ketone (CF/PPEK) and 316L stainless steel with a micro-hemispherical pit textured surface at different sliding speeds under seawater lubrication were studied through numerical simulation and experimental investigation. The study results indicate that the seawater moves following the sliding direction of the upper specimen, forms a vortex ring flow in the hemispherical pit of the bottom specimen, uses the convergent gap to generate a hydrodynamic effect, produces the bearing capacity, and realizes fluid lubrication. The hemispherical pit diminishes the abrasive wear during the friction process by storing the wear debris, and the main wear forms of the hemispherical-pit surface friction pair are oxidative wear and adhesive wear. The friction coefficient of the hemispherical-pit surface friction pair is 0.018–0.027, the specimen contact temperature is 40.2–55.1 °C, and it is always in the hydrodynamic lubrication state in a rotation speed ranging from 1000 r/min to 1750 r/min. As the sliding speed increases, the specimen contact temperature climbs, and the oxidation reaction gradually becomes full. Oxidative wear and adhesive wear alternately play a dominant role in the friction, and the wear rate first decreases and then increases sharply.

The spray atomization properties and droplet turbulence characteristics of a twin-fluid nozzle with and without a self-excited vibrating cavity are investigated and compared using a phase Doppler particle analyzer (PDPA). In the presence of a self-excited vibrating cavity, the spray cone angle and the droplet number concentration increase by nearly 50% and 55%, respectively, and the droplet Sauter mean diameter (SMD) and the mean axial velocity decrease by approximately 40% and 33.8%, respectively. However, the root mean squared (RMS) velocity fluctuation and the droplet turbulence simultaneously worsen. By combining the comparative analysis of the dimensionless parameters of the Reynolds number, Weber number and Ohnesorge number, the results indicate the significant role of the self-excited vibrating cavity in promoting twin-fluid atomization. Quantitative measurements using PDPA with the twin-fluid nozzle in the absence and presence of a self-excited vibrating cavity reveal the effects of the gas to liquid mass flow rate ratio (GLR) on the spray cone angle and the axial distribution of droplet SMD, mean axial velocity and number concentration. The fixed gas flow rate of 0.0003 kg·s−1 and the liquid flow rate of 0.0077 kg·s−1 are selected as representative, and the influence of the structural parameters of a self-excited vibrating cavity on the droplet turbulence characteristics are further investigated. The mean axial velocity along the radial direction first increases as a result of extrusion and diffusion and then decreases, possibly due to the drag effect caused by the surrounding air and droplets; it decreases along the axial direction due to the air resistance. The droplet mean velocity increases with an increase in orifice diameter or orifice depth, and a superior velocity characteristic is obtained when the orifice diameter is 2.5 mm or when the orifice depth is 2.5 mm. Meanwhile, the droplet mean velocity first increases and then decreases with the increase in the distance between the nozzle outlet and the self-excited vibrating cavity, and an appropriate distance value of 4.0 mm is obtained. The variation of RMS velocity fluctuation along the axial direction and radial direction is consistent with the change in mean axial velocity, whereas the droplet turbulence shows an opposite trend. There is a peak of RMS velocity fluctuation and a valley of droplet turbulence at approximately 50 mm from the z-axis. Furthermore, the RMS velocity fluctuation and droplet turbulence increase with the increase in orifice diameter or orifice depth whereas that first increase and then decrease with the increase in the distance between the nozzle outlet and the self-excited vibrating cavity. Thus, the self-excited vibrating cavity profoundly influences the droplet turbulence characteristics by affecting the variation of droplet oscillation.

Bionic non-smooth surface is widely applied in metal and ceramics materials. In order to introduce this technology to high pressure seawater pump, the influence of bionic non-smooth surface on the engineering plastics used in pump should be investigated. The comparative tests are carried out with a ring-on-disc configuration under 800, 1000, 1200 and 1400 r/min in order to research the influence of the bionic non-smooth surface on glass fiber-epoxy resin composite(GF/EPR) under natural seawater lubrication. The disc surfaces are textured with five kinds of pits, which are semi-spherical, conical, cone-cylinder combined, cylindrical pits and through holes, respectively. A smooth surface is tested as reference. The results show that the lubrication performance of dimpled GF/EPR sample is much better than that of the smooth sample under all rotational speeds. The semi-spherical pits surface has more obvious friction reduction than the others, which shows that the least reduction is approximately 43.29% of smooth surface under 1200 r/min. However, the wear level is only marginally influenced by dimples. The surface morphology investigations disclose severe modifications caused by abrasive wear primarily. The results are helpful to vary friction properties of GF/EPR by non-smooth surface, or provide references to the design of non-smooth surfaces under certain condition.

With the development of bionics, the bionic non-smooth surfaces are introduced to the field of tribology. Although non-smooth surface has been studied widely, the studies of non-smooth surface under the natural seawater lubrication are still very fewer, especially experimental research. The influences of smooth and non-smooth surface on the frictional properties of the glass fiber-epoxy resin composite (GF/EPR) coupled with stainless steel 316L are investigated under natural seawater lubrication in this paper. The tested non-smooth surfaces include the surfaces with semi-spherical pits, the conical pits, the cone-cylinder combined pits, the cylindrical pits and through holes. The friction and wear tests are performed using a ring-on-disc test rig under 60 N load and 1000 r/min rotational speed. The tests results show that GF/EPR with bionic non-smooth surface has quite lower friction coefficient and better wear resistance than GF/EPR with smooth surface without pits. The average friction coefficient of GF/EPR with semi-spherical pits is 0.088, which shows the largest reduction is approximately 63.18% of GF/EPR with smooth surface. In addition, the wear debris on the worn surfaces of GF/EPR are observed by a confocal scanning laser microscope. It is shown that the primary wear mechanism is the abrasive wear. The research results provide some design parameters for non-smooth surface, and the experiment results can serve as a beneficial supplement to non-smooth surface study.

Durning the design process of hydrostatic rotary worktable, the processing and assembly tolerance, (the offset of worktable and the gap of the oil film’s thickness) is ignored. But it will cause that the real bearing of oil pocket deviates from the initial design value, and then the performance of rotary worktable will be reduced significantly. Up to now, no effort is found toward the research of influence of the processing and assembly tolerance on the performance of the rotary worktable. So the hydrostatic oil film is assumed as the elastomer in this paper, and then the bearing capacity of the oil pocket is studied with and without the mass offset of the worktable by taking an expression between the bearing capacity and the oil film’s thickness of the oil pocket as the deform compatibility equation. The influence of the processing tolerance of the oil sealing belt’s gap on the bearing capacity of the oil pocket is analyzed. In the light of the liquid hydrostatic worktable of Gantry Moving Milling Center using on the scene, the oil pocket’s pressure of the worktable is tested using Rotary Worktable Test System under the circumstance of the mass offset of the worktable and the gap tolerance of the oil sealing belt, and then the equivalent offset of worktable, the average pressure of the oil pocket and the actual thickness of the oil film are analyzed respectively. The test results show that the bearing capacity component of the oil pocket caused by G is consistent, and the component caused by M is relative to the position of the oil pocket. When the oil sealing belt’s gap is larger than the theoretical value, the bearing capacity of the oil pocket is smaller than the others; whereas the bearing capacity of the oil pocket is larger than the others. The maximum and minimum equivalent offsets are 0.256 4 mm and 0.047 5 mm, respectively, and the average oil pocket pressure varies from 0.345 MPa to 0.460 MPa, the maximum and minimum value of the actual oil film thickness are 109.976 μm (No. 7 oil pocket) and 93.467 μm (No. 10 oil pocket), respectively. The research results can be used to detect the offset of the worktable and the actual thickness of the oil film under processing and assembly tolerance, and provides a basis way for detecting the processing and assembly tolerance of rotary worktable signing reasonably of Gantry Moving Milling Center.