Bifurcations of degenerate homoclinic solutions in discontinuous systems under non-autonomous perturbations.

The main aim of this paper is to study bifurcations of bounded solutions from a degenerate homoclinic solution for discontinuous systems under non-autonomous perturbations. We use Lyapunov-Schmidt reduction to give bifurcation equations and prove that a single parameter is enough to unfold two distinct homoclinic solutions bifurcated from the unperturbed degenerate homoclinic solution. Furthermore, we give an example of a periodically perturbed piecewise smooth differential equation in R4 to support our conclusions.

Modulation of innate immune response to viruses including SARS-CoV-2 by progesterone.

Whether and how innate antiviral response is regulated by humoral metabolism remains enigmatic. We show that viral infection induces progesterone via the hypothalamic-pituitary-adrenal axis in mice. Progesterone induces downstream antiviral genes and promotes innate antiviral response in cells and mice, whereas knockout of the progesterone receptor PGR has opposite effects.

VRK2 is involved in the innate antiviral response by promoting mitostress-induced mtDNA release.

Mitochondrial stress (mitostress) triggered by viral infection or mitochondrial dysfunction causes the release of mitochondrial DNA (mtDNA) into the cytosol and activates the cGAS-mediated innate immune response. The regulation of mtDNA release upon mitostress remains uncharacterized. Here, we identified mitochondria-associated vaccinia virus-related kinase 2 (VRK2) as a key regulator of this process.

Effect of metal-ion doping on the characteristics and photocatalytic activity of TiO2 nanotubes for the removal of toluene from water.

Toluene is an extensively used reagent that could cause water pollution and endanger human health. In this work, an O3/UV/ion-doped TiO2 nanotubes process was investigated to obtain the optimum TiO2 nanotubes for effective toluene decomposition. Photocatalytic activity is found to be influenced by the doped-ion type by affecting the ionic radius, valence state, and configuration of the dopant.

Enhanced photocatalytic degradation of humic acids using Al and Fe co-doped TiO2 nanotubes under UV/ozonation for drinking water purification.

O3/UV/TiO2 was used to effectively decompose humic acids (HAs) in drinking water. To obtain a large specific surface area and low band gap energy, Al and Fe co-doped TiO2 nanotubes were successfully synthesized using the hydrothermal method. The effect of the optimal co-doped TiO2 nanotubes catalyst on the HAs removal efficiency through O3/UV/co-doped TiO2 process was investigated.