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Rock materials are often affected by water in underground engineering. In this study, the mechanical and failure characteristics of tuff under different moisture content were studied using laboratory tests. The moisture content variation of tuff was studied in water absorption tests, and the mechanical and failure characteristics of tuff under different moisture contents were studied through uniaxial compression tests with a Micro-II acoustic emission (AE) control acquisition system. The results showed that the moisture content of tuff increases rapidly at the initial stage of water absorption tests and stabilizes after 180 h of immersion. According to the results of uniaxial compression tests, both uniaxial compressive strength and elasticity modulus decreased with the increase in moisture content. The AE parameters analyses showed that, when the moisture content increased, the accumulated AE counts and energy gradually decreased, and the “quiet period” at the initial stage of uniaxial compression tests lasted longer, and the RA (rise time⁄amplitude)–AF (AE counts⁄duration) distribution and the failure characteristics verified that the failure patterns evolved from shear failure to tensile failure. Scanning electron microscopy was used to observe the morphology of the fracture surface and analyze the influence of moisture content on the fracture characteristics of the tuff at the mesoscopic level. The results of this research can be used as a basis for studying the influence of water on tuff.

Aiming at the problems of the low evaluation efficiency of the existing traditional cardiopulmonary resuscitation (CPR) training mode and the considerable development of machine vision technology, a quality evaluation algorithm for chest compressions (CCs) based on the OpenPose human pose estimation (HPE) model is proposed. Firstly, five evaluation criteria are proposed based on major international CPR guidelines along with our experimental study on elbow straightness. Then, the OpenPose network is applied to obtain the coordinates of the key points of the human skeleton. The algorithm subsequently calculates the geometric angles and displacement of the selected joint key points using the detected coordinates. Finally, it determines whether the compression posture is standard, and it calculates the depth, frequency, position and chest rebound, which are the critical evaluation metrics of CCs. Experimental results show that the average accuracy of network behavior detection reaches 94.85%, and detection speed reaches 25 fps.

Petroleum hydrocarbons can serve as a carbon source for marine phytoplankton, so, marine high-acid crude oil pollution events are likely to result in algal outbreaks or harmful algal blooms (HABs) in surface waters. Naphthenic acids (NAs) are the primary acidic component of crude oil, and red tide is of great concern due to its high diffusivity and strong destructive properties. It is important to study the mechanism of the toxic effect of NAs on the typical red tide algae, Heterosigma akashiwo, for the balance and stability of marine algae. The mechanism of NAs’ damage effect was investigated in terms of the antioxidant enzyme activity, cell number, the chlorophyll positive fluorescence parameters, and the cell morphology of microalgae. Experiments confirmed the hormesis of low-concentration (0.5, 2, and 4 mg/L) NAs on Heterosigma akashiwo, and the indicators of high-concentration (8 and 16 mg/L) NA exposures showed inhibition. In this study, the toxic effect of NAs on the target organism showed a clear concentration–dose relationship. The 16 mg/L NAs stress caused severe damage to the morphology and structure of the target biological cells in a short time (96 h), and the population growth decreased. The target organisms showed a staged oxidative stress response to NAs. The behavior in the low-concentration treatment groups showed toxicant excitatory effects on the photosynthetic efficiency and antioxidant enzyme activity of the target organisms. This study provides theoretical and practical data for the development of an important toxicological model of the toxicant’s excitement effects and antioxidant defense mechanisms. In addition, it provides prospective research data for the prediction and avoidance of ecological risk from NA pollution in marine environments.