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Background: H2S is the third gas transmitter affecting the growth, reproduction and survival of cancer cells. However, the H2S anticancer and antitumor mechanism still needs to be further studied. Methods: Here, FHS-1 was synthesized utilizing excited-state intramolecular proton transfer to detect H2S in MCF-7 cells, and investigated the effects of varying concentrations NaHS on apoptosis. Results: The study found that FHS-1 detects H2S levels with high selectivity and pH stability and that H2S may regulate apoptosis in MCF-7 cells through the p53/mTOR/STAT3 pathway. Conclusion: Researching the influence of H2S on apoptosis can serve as a theoretical foundation for future research into H2S-related anticancer medicines, and the H2S probe can be used as an effective cancer screening tool.

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The characteristics of internal flow and performance of a centrifugal fan is greatly dependent on the inflow pattern. As the fan is subjected to incoming flow from an upstream tube, the size and geometry of the tube affect the three-dimensional motion of local flow and possibly degrades the aerodynamic performance of the fan. In this work, we performed a numerical investigation on the internal flow in a centrifugal fan subjected to incoming flow from an upstream bended inflow tube of various radii using the steady and unsteady Reynolds-averaged Navier-Stokes (RANS and URANS) simulation approaches. The effects of the non-axisymmetric pre-swirl flow generated due to the curvature of the bended inflow tube are demonstrated by analyzing the internal flow characteristics of the fan, including the spatial distributions and temporal variations of pressure field and streamlines, pressure fluctuations in the upstream tube, the inflow and outflow sections of the impeller, and the circumferential distributions of velocity and pressure in the impeller. The numerical results reveal that as the inflow tube is curved with larger curvature (smaller radius of the bended section), the pre-swirl inflow is strong and deteriorates the static pressure rise and static pressure efficiency of the centrifugal fan more remarkably, and the circumferential non-uniformity of pressure and velocity distributions appears inside of the channels of the fan. As the radius of the bended section increases, the instability of the internal flow gets more pronounced, as represented by the stronger pressure fluctuations at the inflow and outflow sections. The prediction capabilities of RANS and URANS approaches are also analyzed based on the numerical data and we found that the latter is more reliable in predicting the performance of the fan.

The impeller of double-suction centrifugal fans may be radially offset from the centerline of the volute due to faults in assembly or installation. The radial offset results in the more significant non-uniformity of internal flow in the centrifugal fan, which is biased from the designed condition, and deteriorates the aerodynamic performances of the fan. In this paper, we performed Unsteady Reynolds-averaged Navier–Stokes (URANS) simulations on the unsteady internal flow of a double-suction centrifugal fan. The impeller of the fan is offset in the radial direction from its original position and is thus closer to the wall of the volute on one side and away from the opposite side. Numerical results show that the offset impeller changes the size of the gap between the impeller and collector in the radial direction, which produces a non-uniform distribution of static pressure and even reversed flow at the inlet of the impeller. As the impeller is offset away from the baffle of the volute, reversed flow back into the volute is observed, and strong circulating vortices form around the baffle, which weakens the diffusing capability of the volute. However, as the impeller is offset close to the baffle, the internal flow of the volute generally improves the flow patterns within the impeller, while the boundary layer separates from the pressure surface of the blades near the front disc as the flow angle varies; the maximum velocity of reversed flow could reach 20 m/s which lowers the efficiency of the fan.