The RAS signaling pathway is hyperactive in malignant glioma due to overexpression and/or increased activity. A previous study identified that RASD1, a member of the RAS superfamily of small G-proteins, is a significantly dysregulated gene in oligodendroglial tumors that responded to chemotherapy. However, the role and mechanism of RASD1 in the progression of human glioma remain largely unknown. In the present study, by analyzing a public genomics database, we found that high levels of RASD1 predicted good survival of astrocytoma patients. We thus established lentivirus-mediated RASD1-overexpressing glioma cells and found that overexpressing RASD1 had no significant effects on glioma cell proliferation. However, the overexpression of RASD1 inhibited glioma cell migration and invasion. In the intracranial glioma xenograft model, the overexpression of RASD1 significantly reduced the number of tumor cells invading into the surrounding tissues without affecting the tumor size. An intracellular signaling array revealed that the phosphorylation of both AKT and the S6 ribosomal protein significantly decreased with RASD1 overexpression in glioma cells. Interestingly, RASD1 protein levels were significantly higher in grade II and grade III astrocytoma tissues than in nontumorous brain tissues. These findings suggest that the upregulation of RASD1 in glioma tissues may play an inhibitory role in tumor expansion, possibly through inactivating the AKT/mTOR signaling pathway.
Summary. Interior noise in rolling stock is an important index in the evaluation of passenger ride comfort. In this paper, the hybrid FE-SEA method was used to predict the interior noise of high-speed trains. In this process, the hybrid model of the car body was established based on FE models. Then according to the characteristic of the car body, the beams and stiffeners were described by a FE subsystem and thin, light plates and panels were divided into a SEA subsystem. As for the special structure of hollow aluminium alloy extrusion which makes up the car body profile, the equivalent model of a General Laminate was proposed to simplify this structure in the paper. Through theoretical calculation and test, subsystem parameters and external excitations were obtained, and then imported into the prediction model. Finally noise at the central section of the high-speed train was predicted by using the hybrid FE-SEA model. Compared with the test results, in the frequency range of 100 ~ 1000 Hz, the predicted and test noise spectra followed basically the same trend, so the proposed Hybrid FE-SEA method can be efficiently applied to the railway field.
The fan is the main component of the cooling system of an automobile engine. A typical automobile cooling fan consists of a shrouded axial fan, stator vanes, a deflector, and a cover. With recent developments in the automobile industry, the increase in the speed of rotation and blade load of cooling fans has increased the noise generated by them. To reduce it, it is important to analyze the characteristics of this noise. This paper uses an acoustic test to examine the characteristics of flow and noise of automobile cooling fans. The frequency spectrum and far-field radiation of the noise of the fan are first analyzed through far-field measurements, and the influence of the single rotor, tip clearance of the blade, and cover on fan noise is studied. The distribution of the mode spectrum and characteristics of sound propagation of discrete tonal noise are then examined using the circumferential mode test. The influence of the flow structure on fan noise is also studied. The flow characteristics and distribution of the source of noise of the automobile cooling fan are then used to analyze the influence of the structure of the fan on the noise generated by it. The results can help develop designs to reduce the noise of automobile cooling fans.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.