The complexity of human DNA has been affected by aerobic metabolism, including endurance exercise and oxygen toxicity. Aerobic endurance exercise could play an important role in the evolution of Homo sapiens, and oxygen was not important just for survival, but it was crucial to redox-mediated adaptation. The metabolic challenge during physical exercise results in an elevated generation of reactive oxygen species (ROS) that are important modulators of muscle contraction, antioxidant protection, and oxidative damage repair, which at moderate levels generate physiological responses. Several factors of mitochondrial biogenesis, such as peroxisome proliferator-activated receptor-c coactivator 1a (PGC-1a), mitogen-activated protein kinase, and SIRT1, are modulated by exercise-associated changes in the redox milieu. PGC-1a activation could result in decreased oxidative challenge, either by upregulation of antioxidant enzymes and/or by an increased number of mitochondria that allows lower levels of respiratory activity for the same degree of ATP generation. Endogenous thiol antioxidants glutathione and thioredoxin are modulated with high oxygen consumption and ROS generation during physical exercise, controlling cellular function through redox-sensitive signaling and proteinprotein interactions. Endurance exercise-related angiogenesis, up to a significant degree, is regulated by ROSmediated activation of hypoxia-inducible factor 1a. Moreover, the exercise-associated ROS production could be important to DNA methylation and post-translation modifications of histone residues, which create heritable adaptive conditions based on epigenetic features of chromosomes. Accumulating data indicate that exercise with moderate intensity has systemic and complex health-promoting effects, which undoubtedly involve regulation of redox homeostasis and signaling. Antioxid. Redox Signal. 18, 1208Signal. 18, -1246
Stainless steel wire mesh packing is widely used for experimental and industrial applications in rotating packed beds (RPBs) for gas−liquid contacting because it has a higher mass-transfer performance than other conventional packings. In this work, the gas−liquid effective interfacial area of a conventional RPB was studied with eight types of stainless steel wire mesh packings, consisting of four different stainless steel fibers. Gas−liquid chemisorption with CO 2 in NaOH solution was employed to measure the effective interfacial area for all types of packings with different rotational speeds and gas−liquid ratios. An empirical correlation that takes the effects of the fiber diameter and opening size of the wire mesh into consideration was proposed for the calculation of the gas−liquid effective interfacial area of stainless steel wire mesh packings in a conventional RPB.
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