A Novel Distributed Vibration Sensor Based on Fading Noise Reduction in Multi-Mode Fiber.

Multi-mode fiber (MMF) is used in a polarization-sensitive optical time domain reflectometer (OTDR) for vibration event location and spectrum analysis. The vibration events acting on MMF are considered to be the optical polarization state and phase diversifying process for fading noise reduction. In addition, data averaging with continuous positions and the fast Fourier transform (FFT) method is proposed to extract the spectrum of the vibration events. In the experiment, the vibration events are loaded at the positions of 5.167 and 10.145 km, respectively, along MMF. The experimental results demonstrate that the vibration event can effectively diversify the optical polarization state and phase of the Rayleigh scattering light to make the averaged OTDR trace behind the vibration position converge rapidly, which helps to locate corresponding vibration events and extract the vibration spectrum. It is inferred that the new distributed vibration sensor shall have a lower false alarm rate, as it can greatly reduce the errors caused by randomness of the sensing light signals. Additionally, it also saves time in comparison with the method that analyzes the vibration spectra for all the positions along the fiber under test.

Fibroblast growth factor 21 improves lipopolysaccharide-induced pulmonary microvascular endothelial cell dysfunction and inflammatory response through SIRT1-mediated NF-κB deacetylation.

Pneumonia is a common infectious disease of the respiratory system in children. It often leads to death in children by causing acute lung injury. Fibroblast growth factor 21 (FGF21) is a peptide hormone that plays an important role in the regulation of energy homeostasis. This study aimed to investigate the role of FGF21 in alleviating the lipopolysaccharide (LPS)-induced human pulmonary microvascular endothelial cell (HPMEC) injury, as well as the underlying mechanism. The expression of sirtuin 1 (SIRT1), NF-κB p65, Ac-NF-κB p65, apoptosis-related proteins, tight junction proteins and adhesion molecules in HPMECs were analyzed by Western blotting. The viability and apoptosis of HPMECs were detected by CCK-8 and TUNEL assays. Lactate dehydrogenase level and levels of inflammatory factors were respectively determined by assay kits. The mRNA expression of adhesion molecules in HPMECs was analyzed by RT-qPCR. As a result, SIRT1 expression was decreased and the expression of NF-κB p65 and Ac-NF-κB p65 were increased in LPS-induced HPMECs, which were reversed by recombinant FGF21 (rFGF21). rFGF21 increased the viability and inhibited the apoptosis, inflammatory response, permeability, and release of cell adhesion molecules of LPS-induced HPMECs. In addition, EX527 as SIRT1 inhibitor could reverse the effect of rFGF21 on LPS-induced HPMECs. In conclusion, FGF21 improved LPS-induced HPMEC dysfunction and inflammatory response through SIRT1-mediated NF-κB deacetylation.