Photocatalysis is a promising technology for wastewater treatment, particularly for mineralization of nonbiodegradable and toxic components in wastewater. TiO 2 is usually utilized as photocatalyst in slurry reactors in order to overcome mass transfer limitations. The difficulty in recovering TiO 2 photocatalyst from treated water hindered its wide application. In this work, a novel process efficiently integrating sonophotocatalysis for methyl orange degradation and ultrasonic-enhanced ceramic membrane microfiltration for TiO 2 separation was proposed and demonstrated. The results indicated that ultrasonic introduction could enhance photocatalysis reaction rate through cavitation effect, a synergetic effect between sonolysis and photocatalysis was found, and that is closely related with working conditions. Ceramic membrane microfiltration could efficiently recover TiO 2 photocatalyst with a mean granular size of 0.33 μm from slurry reactor, achieving 99.9% recovery rate. Ultrasonic introduction into microfiltration process efficiently increased transmembrane permeation flux, suppressing membrane fouling under optimal working conditions. However, due to the problems associated with conversion efficiency of ultrasonic energy and the uncertain synergistic effect of sonolysis and photocatalysis, there is still much work before application of this process for wastewater treatment.
High-altitude cerebral edema (HACE) is a potentially fatal encephalopathy associated with a time-dependent exposure to the hypobaric hypoxia of altitude. The formation of HACE is affected by both vasogenic and cytotoxic edema. The over-activated microglia potentiate the damage of blood–brain barrier (BBB) and exacerbate cytotoxic edema. In light with the activation of microglia in HACE, we aimed to investigate whether the over-activated microglia were the key turning point of acute mountain sickness to HACE. In in vivo experiments, by exposing mice to hypobaric hypoxia (7000 m above sea level) to induce HACE model, we found that microglia were activated and migrated to blood vessels. Microglia depletion by PLX5622 obviously relieved brain edema. In in vitro experiments, we found that hypoxia induced cultured microglial activation, leading to the destruction of endothelial tight junction and astrocyte swelling. Up-regulated nuclear respiratory factor 1 (NRF1) accelerated pro-inflammatory factors through transcriptional regulation on nuclear factor kappa B p65 (NF-κB p65) and mitochondrial transcription factor A (TFAM) in activated microglia under hypoxia. NRF1 also up-regulated phagocytosis by transcriptional regulation on caveolin-1 (CAV-1) and adaptor-related protein complex 2 subunit beta (AP2B1). The present study reveals a new mechanism in HACE: hypoxia over activates microglia through up-regulation of NRF1, which both induces inflammatory response through transcriptionally activating NF-κB p65 and TFAM, and enhances phagocytic function through up-regulation of CAV-1 and AP2B1; hypoxia-activated microglia destroy the integrity of BBB and release pro-inflammatory factors that eventually induce HACE.
Local mean decomposition (LMD) is a new time-frequency analysis method which can decompose a signal adaptively into a set of product function (PF) components, and the construction of local mean function and envelope function plays an important role in the accuracy of its PF components. Aiming at the strong nonstationarity, nonlinearity and multi-component coupling characteristics of reciprocating compressor vibration signals, an improved LMD was proposed by a novel construction method of local mean function and envelope function. By introducing an extreme symmetrical point between two extreme points and using the Monotone Piecewise Cubic Hermite Interpolation (MPCHI) instead of Cubic Spline Interpolation (CSI) to construct the envelopes, a novel construction method of local mean function and envelope function was proposed, and then the improved LMD algorithm was given based on this novel construction method. The improved LMD was applied to decompose the vibration signals of reciprocating compressor fault states, and the comparison of details between different LMD decomposition results verified the superiority of this improved method. The envelope frequency spectrum of PF component gives a more significant peak of fault frequency than that of original signal, which further indicates that this proposed method is competent for the diagnosis of reciprocating compressor oversized bearing clearance fault.
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