The long service life and high reliability of SiC sliding bearings are crucial for the long-term normal operation of aerospace power equipment.In response to the fracture phenomenon observed in the sliding bearing assembly of a certain delivery pump during operation,this paper analyzes the issue from the perspectives of stress characteristics and thermal expansion effects,proposing a structural optimization design method based on temperature coefficient compensation.The research indicates that the primary cause of bearing fracture is the difference in thermal expansion coefficients between the bearing and the metal rotor under elevated temperatures,leading to axial loosening of the bearing.Additionally,the gap between the bearing and the pin,combined with unstable lubrication of the friction pair,exacerbates bearing stalling and pin impact,ultimately causing cracks and localized chipping.By optimizing the bearing structure and employing a rubber pad for torque transmission,this issue has been successfully resolved.The improved structure demonstrated high reliability and stability in bench tests,providing important theoretical and technical references for the design of bearings under similar extreme operating conditions.

Sphingomyelinases (SMase) are the main enzymes that regulate the signaling pathway of sphingomyelin and the metabolism of related products, and they are involved in the key steps of the complex metabolic process of sphingomyelin. In recent years, many studies have shown that SMase is involved in the biological processes such as cell cycle arrest, cell migration, and inflammation and promotes the development and progression of hepatocellular carcinoma by regulating the apoptosis and proliferation of tumor stem cells. SMase has an important potential biological value in the development, progression, diagnosis, and treatment of hepatocellular carcinoma. This article summarizes the exact role of SMase in the development and progression of hepatocellular carcinoma, in order to provide new ideas and strategies for the clinical treatment of hepatocellular carcinoma and the development of new drugs.

Objective:To study and explore the effect and mechanism of action of Jieduhuayu granules on oxidative injury of human liver L02 cells.Methods:Human liver L02 oxidative injury model was established with 0.1 mmol/ L H 2O 2 intervention for 1 h, and treated with different concentrations of Jieduhuayu (JDHY) solution. Hepatocytes were divided into five groups: normal, H 2O 2, H 2O 2 + JDHY (0.5 mg/ml), H 2O 2 + JDHY (1 mg/ml), and H 2O 2 + JDHY (1.5 mg/ml). MTT assay was used to detect hepatocytes activity. Transmission electron microscope was used to observe mitochondrial morphology in hepatocytes. Biochemical test was used to detect the levels of superoxide dismutase, lactate dehydrogenase, alanine aminotransferase, aspartate aminotransferase, malondialdehyde, and reduced glutathione and albumin in hepatocytes. Western blot was used to detect the expression levels of rabbit anti-phosphatidylinositol 3-kinase (PI3K), AKT and mTOR in hepatocytes. One-way analysis of variance was used for comparison between multiple groups, and the LSD method was used for pairwise comparison. Results:Compared with the normal group, the cell proliferation activity ( P < 0.05), mitochondrial vacuolization, superoxide dismutase activity, reduced albumin and glutathione content, and PI3K, AKT, and mTOR protein expression levels in the H 2O 2 group were all significantly reduced ( P < 0.05), while the content of malondialdehyde and the activities of alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase were significantly increased ( P < 0.05). Compared with H 2O 2 group, the cell proliferation activity ( P < 0.05), alterations in morphological remission of mitochondria, superoxide dismutase activity, reduced albumin and glutathione content, and PI3K, AKT and mTOR protein expression levels in the H 2O 2 + JDHY (1 mg/ml) and H 2O 2 + JDHY (1.5 mg/ml) group ( P < 0.05) were all significantly increased ( P < 0.05), while malondialdehyde content and alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase activities were significantly decreased ( P < 0.05). Conclusion:Jieduhuayu granule can effectively improve oxidative stress and mitochondrial injury in hepatocytes, and its effect may be related to the promoting expression of PI3K/AKT/mTOR signaling pathways.

Objective To observe the expression of high mobility group A 1(HMGA1)protein in pituitary adenoma(PA)and explore its relationship with the aggressiveness and recurrence of PA .Methods The labeling index(LI)of HMGA1, detected by immunohistochemistry staining , was compared between aggressive and non-ag-gressive PA, recurrent and non-recurrent PA.Results The expression of HMGA1 were observed in all 52 cases of PA and homogenously distributed in nuclear of tumor cells .The LI of HMGA1 showed no significant difference between functioning and nonfunctioning PA (P=0.79), as well as among different immunophenotypical variants of PA(P=0.28).The expression of HMGA1 was significantly higher in the aggressive PA than in the nonaggres-sive PA(0.50 ±0.20 vs 0.24 ±0.17, P=0.000).Patients with a recurrent PA had a higher value of HMGA 1 than patients with a non-recurrent PA(0.60 ±0.20 vs 0.24 ±0.18, P=0.000).The expression of HMGA1 in-creased stepwise with the tumor size, as the highest was present in macro-sized PA(0.52 ±0.20)and the lowest was in micro-sized PA(0.18 ±0.17).A similar trend was found in Hardy's grade I(0.18 ±0.17),II(0.30 ± 0.20)and III-IV(0.50 ±0.20)(P=0.003).The area under the ROC curve was 0.918(>0.90).When the LI reached 49.2%, the predicting specificity was 90.5%and the sensitivity was 71.4%.Conclusions The LI of HMGA1 has a positive correlation with the tumor size , aggressiveness and recurrence of PA and also has a valua-ble predicting efficacy for PA recurrence .The characteristics of HMGA 1 in PA can help pathologists make repro-ducible evaluation on prognosis of PA .

Objective To study changes and significance of endothelin(ET) in rat cerebral concussion.Methods 80 Wistar male rats were used for animal model of cerebral concussion,which were sacrificed on 1,3,7,14 and 30 days after injury and the brain tissue were taken off. The expression of ET was studied in the course of cerebral concussion by means of immunohistochemistry.Results Typical clinical manifestation was observed in the 100 g group in which the pathological changes included cerebral vascular constriction and dilatation,congestion and edema of cerebral tissue,neuronal degeneration,necrosis,and obviously decreased even disappeared Nissl bodies.Increased expression of ET was observed on the first day,the positive area was seen in the plasma of endothelial cells in cerebral cortex,hippocampus,cerebellum and thalamus.ET expression peak occurred on the 7th day,the positive area was also found in the plasma of Purkinje cells in the cerebellum.Decreased ET expression was found on 14th day and returned to normal level on the 30th day.Conclusion The main pathological changes of cerebral concussion contained blood circulation disorder,and degeneration and necrosis of substantial cells.ET was involved in the brain tissue injury during the pathological process of cerebral concussion and might be related to regulation of cerebral vascular reaction,and neuron degeneration and necrosis.