Numerical and Experimental Research on Vibration Mechanism of Rotary Compressor

With a typical rotary compressor as the research object, the vibration mechanism of the rotary compressor was analyzed in detail in this work. And according to the work, the formulations of the tangential vibration and the radial vibration were proposed for the rotary compressor. First, the oil film stiffness and the damp coefficient were obtained by coupling the experimental testing method and numerical simulation. Then a dynamics simulation was conducted for the rotor system and the critical speed for the current rotor system was obtained, which was used to judge if the rotor system is a kind of flexible rotor. After that, with the aerodynamic force and the crankshaft deformation under consideration, the electromagnetic force, the electromagnetic torque and the revolution fluctuation rate were calculated and analyzed based on an electromagnetic simulation analysis for the motor of the rotary compressor. Finally, the tangential vibration and the radial vibration on the shell and the reservoir of the rotary compressor were obtained by using a dynamics simulation with the revolution fluctuation rate as the load for the rotor system. Based on the simulation result, the predicted results match well with the experimental test results. This work in this paper and the method used in this work provide a good reference for prediction of the vibration and resolving vibration problem of the rotary compressor

Time constraints on the closure of the Paleo–South China Ocean and the Neoproterozoic assembly of the Yangtze and Cathaysia blocks: Insight from new detrital zircon analyses

International audienceThe South China Block was built up by the assembly of the Yangtze and Cathaysia blocks along the Neoproterozoic Jiangnan Orogenic Belt. The timing of the Jiangnan Orogeny remains controversial. The widespread orogeny–related Neoproterozoic angular unconformity that separates the underlying folded Sibao (ca.1000–820 Ma) and overlying Danzhou (ca.800–720 Ma) Groups was investigated. Six sedimentary samples, below and above the unconformity in three distal localities (Fanjingshan, Madiyi, and Sibao) yield detrital zircon with UPb ages ranging from 779 ± 16 Ma to 3006 ± 36 Ma, with a prominent peak at ca. 852 Ma. The youngest ages of 832 ± 11 Ma and 779 ± 16 Ma are revealed for the underlying Sibao and overlying Danzhou Groups, respectively. The detrital zircon UPb age relative probability plot of the Jiangnan Orogen matches well with those of the Yangtze and Cathaysia blocks since ca. 865 Ma. Integrating geological, geochemical and geochronological results, we suggest that the Paleo–South China Ocean began to subduct under the Yangtze block at ca. 1000 Ma, and was partly closed at ca. 865 Ma. Afterwards, the Yangtze and Cathaysia blocks initially collide at 865 Ma, forming the Jiangnan Orogen. This collision resulted in not only the folding of the Sibao Group, but also sediment deposition in a syn-collisional setting, which makes the upper part of the Sibao Group. The youngest S-type granite dated at ca. 820 Ma that intruded in the Sibao Group marks the late stage of the Jiangnan Orogeny

Numerical Analysis on the Influence of Joint Density on the Stability of Complex Jointed Roadway Surrounding Rock

The random distribution of a complex joint network within a coal–rock mass has a significant weakening effect on its bearing capacity, making the surrounding rock of the roadway highly susceptible to instability and failure under the influence of in situ stress and mining-induced stress. This poses challenges in controlling the surrounding rock and seriously affects the normal production of mines. Consequently, it is imperative to conduct stability analysis on complex jointed roadway surrounding rock. Therefore, taking the transport roadway of Panel 11030 in the Zhaogu No. 2 Coal Mine as a case study, the microscopic contact parameters of particles and joint surfaces in each rock layer were calibrated through uniaxial compression and shear simulation tests using the particle flow simulation software PFC2D 5.0. Based on the calibrated microscopic contact parameters, a multilayered roadway surrounding rock model containing complex joints was established, and the joint density was quantified to analyze its effects on the displacement field, stress field, force chain field, and energy field of the roadway surrounding rock. The research findings indicate that as the distance to the sidewall decreases, the impact of joint density on the deformation of the surrounding rock of the roadway increases. The displacement of the roadway roof, floor, and sidewalls is affected differently by the joint density, predominantly contingent upon the properties of the rock mass. During the process of stress redistribution in the surrounding rock, the vertical stress of the roof and floor is released more intensively compared to the horizontal stress, while the horizontal stress of the sidewalls is released more intensively compared to the vertical stress. The increase in joint density leads to an increasing release rate of the surrounding rock stress, causing the load-bearing rock mass to transfer towards the deeper part. As the joint density increases, the force chain network gradually transitions from dense to sparse, resulting in a decrease in strong force chains and a decline in the bearing capacity of the surrounding rock, accompanied by an expansion in the range of force chain failure and deformation. With the continuous increase in joint density, the values of maximum released kinetic energy and residual released kinetic energy become larger. Once the joint density reaches a certain threshold, the kinetic energy stability zone consistently maintains a high energy level, indicating extreme instability in the roadway and sustained deformation. The results provide a valuable insight for analyzing the failure mechanism of complex jointed roadway surrounding rock and implementing corresponding support measures

Can glypican-3 be a disease-specific biomarker?

Abstract Background Glypican-3 (GPC3) is a cell surface-bound proteoglycan which has been identified as a potential biomarker candidate in hepatocellular carcinoma, lung carcinoma, severe pneumonia, and acute respiratory distress syndrome (ARDS). The aim of our review is to evaluate whether GPC3 has utility as a disease-specific biomarker, to discuss the potential involvement of GPC3 in cell biology, and to consider the changes of GPC3 gene and protein expression and regulation in hepatocellular carcinoma, lung cancer, severe pneumonia, and ARDS. Results Immunohistochemical studies have suggested that over-expression of GPC3 is associated with a poorer prognosis for hepatocellular carcinoma patients. Expression of GPC3 leads to an increased apoptosis response in human lung carcinoma tumor cells, and is considered to be a candidate lung tumor suppressor gene. Increased serum levels of GPC3 have been demonstrated in ARDS patients with severe pneumonia. Conclusions Glypican-3 could be considered as a clinically useful biomarker in hepatocellular carcinoma, lung carcinoma, and ARDS, but further research is needed to confirm and expand on these findings

Efficient Aerobic Oxidation of Glucose to Gluconic Acid over Activated Carbon-Supported Gold Clusters

The catalytic performance of the atomically precise gold cluster-Au-38(PET)(24) (PET=2-phenylethanethiolate), immobilized on activated carbon (AC), was investigated for the aerobic oxidation of glucose to gluconic acid. The Au-38(PET)(24)/AC-120 catalysts, annealed at 120 degrees C in air, exhibited high catalytic activity and significantly better performance than the corresponding catalysts Au-38/AC-150 and Au-38/AC-300 (treated at 150 and 300 degrees C to remove the protecting thiolate ligands). The high activity of the robust Au cluster was a result of the partial ligand removal, providing catalytically active sites, which were evidenced by TEM, X-ray photoelectron spectroscopy, thermogravimetric analysis, and Fourier-transform IR spectroscopy. Au-38(PET)(24)/AC-120 also showed excellent recyclability (up to seven cycles). The turnover frequency for the Au-38(PET)(24)/AC-120 catalyst was 5440h(-1), which is higher than for the Pd/AC, Pd-Bi/AC, and Au/AC under identical reaction conditions. This new ultra-small gold nanomaterial is expected to find wide application in other catalytic oxidations