The fluid flow and heat transfer of hydrocarbon fuel play a significant role in developing regenerative cooling technology for advanced aeroengines. Numerical simulations have been conducted to investigate the flow and heat transfer characteristics of China RP-3 aviation kerosene with pyrolysis in a 3D, 90° bend, square cooling channel around the cavity flame-holder of a scramjet. A chemical kinetic model, composed of 18 species and 24 reactions, was adopted to simulate the fuel pyrolysis process. Results indicate that the secondary flow enhances the mixing of the fluid, thus, the transports of heat and components are improved between the near-wall region and main flow field in the curved channel. Compared with a straight cooling channel, fuel conversion and heat-absorbing capacity are higher, and the heat transfer is effectively enhanced in a curved cooling channel. In addition, with the increasing inlet mass flow rate and the decreasing radius of curvature, the velocity of the secondary flow increases. The heat and components are easily transferred from the near-wall region to the main flow. The non-uniformities of fuel temperature and conversion at the cross section decreases, which is helpful for improving the utilization of the level of fuel heat-absorbing capacity, and beneficial for enhancing the heat transfer.

Culture of hippocampal neurons in low-Mg²⁺ medium (low-Mg²⁺ neurons) results in induction of continuous seizure activity. However, the underlying mechanism of the contribution of low Mg²⁺ to hyperexcitability of neurons has not been clarified. Our data, obtained using the patch-clamp technique, show that voltage-gated Na⁺ channel (VGSC) activity, which is associated with a persistent, noninactivating Na⁺ current ( I_Na,P), was modulated by calmodulin (CaM) in a concentration-dependent manner in normal and low-Mg²⁺ neurons, but the channel activity was more sensitive to Ca²⁺/CaM regulation in low-Mg²⁺ than normal neurons. The increased sensitivity of VGSCs in low-Mg²⁺ neurons was partially retained when CaM₁₂ and CaM₃₄, CaM mutants with disabled binding sites in the N or C lobe, were used but was diminished when CaM₁₂₃₄, a CaM mutant in which all four Ca²⁺ sites are disabled, was used, indicating that functional Ca²⁺-binding sites from either lobe of CaM are required for modulation of VGSCs in low-Mg²⁺ neurons. Furthermore, the number of neurons exhibiting colocalization of CaM with the VGSC subtypes Na_V1.1, Na_V1.2, and Na_V1.3 was significantly higher in low- Mg²⁺ than normal neurons, as shown by immunofluorescence. Our main finding is that low-Mg²⁺ treatment increases sensitivity of VGSCs to Ca²⁺/CaM-mediated regulation. Our data reveal that CaM, as a core regulating factor, connects the functional roles of the three main intracellular ions, Na⁺, Ca²⁺, and Mg²⁺, by modulating VGSCs and provides a possible explanation for the seizure discharge observed in low-Mg²⁺ neurons.