Rail vehicle dynamic response to a nonlinear physical ‘in-service’ model of its secondary suspension hydraulic dampers

A full nonlinear physical ‘in-service’ model was built for a rail vehicle secondary suspension hydraulic damper with shim-pack-type valves. In the modelling process, a shim pack deflection theory with an equivalent-pressure correction factor was proposed, and a Finite Element Analysis (FEA) approach was applied. Bench test results validated the damper model over its full velocity range and thus also proved that the proposed shim pack deflection theory and the FEA-based parameter identification approach are effective. The validated full damper model was subsequently incorporated into a detailed vehicle dynamics simulation to study how its key in-service parameter variations influence the secondary-suspension-related vehicle system dynamics. The obtained nonlinear physical in-service damper model and the vehicle dynamic response characteristics in this study could be used in the product design optimization and nonlinear optimal specifications of high-speed rail hydraulic dampers

Viability analysis and apoptosis induction of breast cancer cells in a microfluidic device: effect of cytostatic drugs

Breast cancer is the leading cause of cancer deaths among non-smoking women worldwide. At the moment the treatment regime is such that patients receive different chemotherapeutic and/or hormonal treatments dependent on the hormone receptor status, the menopausal status and age. However, in vitro sensitivity testing of tumor biopsies could rationalize and improve the choice of chemo- and hormone therapy. Lab-on-a-Chip devices, using microfluidic techniques, make detailed cellular analysis possible using fewer cells, enabling working with a patients’ own cells and performing chemo- and hormone sensitivity testing in an ex vivo setting. This article describes the development of two microfluidic devices made in poly(dimethylsiloxane) (PDMS) to validate the cell culture properties and analyze the chemosensitivity of MCF-7 cells (estrogen receptor positive human breast cancer cells) in response to the drug staurosporine (SSP). In both cases, cell viability was assessed using the life-stain Calcein-AM (CAAM) and the death dye propidium iodide (PI). MCF-7 cells could be statically cultured for up to 7 days in the microfluidic chip. A 30 min flow with SSP and a subsequent 24 h static incubation in the incubator induced apoptosis in MCF-7 cells, as shown by a disappearance of the aggregate-like morphology, a decrease in CAAM staining and an increase in PI staining. This work provides valuable leads to develop a microfluidic chip to test the chemosensitivity of tumor cells in response to therapeutics and in this way improve cancer treatment towards personalized medicine

Experimental and numerical studies on the spray cooling of deionized water in non-boiling regime

High-efficiency spray cooling technology has received increase of interest for high heatflux applications. Experimental and numerical investigations on spray heat transfer in single-phase deionized water are reported in this paper. The 3D numerical model is established based on Discrete Phase Model and Lagrange Wall Film model, comprehensively considering the exchange of mass, momentum and energy between the air (continuous phase) and water droplets (discrete phase), and the heat transfer in liquid film at the heated surface. PDA is adopted to measure Sauter Mean Diameter (SMD) of near-wall droplets. The influences of mass flow rates, nozzle diameters and spray heights on spray heat transfer characteristics are discussed. Results indicate that increasing mass flow rate can reduce SMD due to high We number and improve heat transfer coefficient. Liquid-film thickness is high at either low or high mass flow rate, but has minor influence on cooling performance. The optimal nozzle diameter is 0.6 mm rather than the smaller or higher diameter because the spray area is similar to the heated area. Similar reason is for the optimal spray height of 20 mm