Physical and chemical dynamics at Jiangjia Spring (JJS), the outlet of the Qingmuguan karst groundwater system in Chongqing, were monitored in situ during rainfall events to acquire a series of high-resolution data. Principal component analysis (PCA) was employed to identify the sources of chemical compositions in the karst groundwater. The coefficients of variations (CVs) of the physical and chemical data of JJS were utilized to interpret the migration path of the chemical compositions. The results showed that water-rock interactions, agricultural activities, and soil erosion were the main sources of the groundwater chemical compositions. Ions of potassium, sodium, nitrate, chloride and phosphate from agricultural activities together with ions of calcium, magnesium, strontium and bicarbonate derived from carbonate dissolution appear to be stored and regulated by the karst unsaturated zone in features such as fissures, pores and solution cracks. The concentrations of the ions remained relatively stable and they showed low CVs owing to their migration by diffuse flow to recharge the underground river. In contrast, concentrations of ions such as total iron, total manganese and aluminum from soil erosion were unstable and showed high CVs owing to their migration by overland flow to recharge the underground river directly via sinkholes. During heavy rainfall events, the nutrients from agricultural activities and sediment from soil erosion could quickly impair the aquatic ecosystem and pose serious threats to water quality. Therefore, it is necessary to reinforce management of the ecological system for better control of the influx of mass nutrients into the karst aquifer system.

In this study, an outer surface modified polyvinylidene fluoride (PVDF) hollow fiber membrane (HF-PVDF-CNT) was prepared by coating with dopamine (PD) and multiwalled carbon nanotubes (CNTs), to solve the problems of the instability of pure CNT mats fabricated by filter coating methods and membrane fouling in wastewater treatment. The modified membrane was assessed and characterized by various methods, including studies of its top surface and cross-sectional morphology, wettability, functional groups and electrical conductivity. The CNT material stability was evaluated during backwashing. The antifouling and filtering abilities of the unmodified and modified membranes were tested by monitoring the change in TMP and the rejection performance for different contaminants during filtration in bovine serum albumin solution (BSA), sodium alginate solution (SA) and humic acid solution (HA). Furthermore, HF-PVDF-CNT and electro-assisted HF-PVDF-CNT membranes were employed as the basic separation units in an anaerobic membrane bioreactor (AnMBR) system and an anaerobic electrochemical membrane bioreactor (AnEMBR) system, respectively. Characterization of the HF-PVDF-CNT membrane indicated that the CNT mats exhibited good stability, electrical conductivity and wettability. In filtration experiments using BSA, SA and HA solutions, the HF-PVDF-CNT membrane showed an obvious improvement compared with the HF-PVDF membrane in antifouling performance. During its application in the AnMBR and AnEMBR systems, the electro-assisted HF-PVDF-CNT membrane had greater effects than the HF-PVDF-CNT membrane on reducing fouling.

Due to the transfer of Lannigou gold mining from shallow to deep, a series of stability problems of surrounding rock have been caused. The drilling pressure relief technology has unique advantages in the control of mine pressure in high-stress roadways. In order to explore the damage effect of borehole pressure relief technology on rock, uniaxial compression and acoustic emission tests were carried out on siltstone specimens with borehole diameters of 8 mm, 12 mm, and 16 mm, respectively, and the acoustic emission signals of the whole process were collected simultaneously to explore the uniaxial compression of siltstone specimens with prefabricated holes in this paper. According to the statistical characteristics of acoustic emission, the damage law of siltstone specimens with prefabricated holes was explored from the microscopic point of view and the damage effect of drilling on siltstone specimens reflected by the acoustic emission phenomenon was revealed. The research results show that there are multiple stress drops before the deformation and failure of the rock sample with prefabricated drill holes; there is a positive correlation between the diameter of the drill hole and the power law index of the stress drop distribution; the acoustic emission activity of the rock during the deformation and failure process can be indirectly reflected the evolution of microfractures; the energy probability density function under different borehole diameters conforms to the power law distribution; the critical exponent obtained by the maximum likelihood estimation has an optimal plateau value, which can accurately characterize the power exponent of the energy distribution; the launch waiting time and aftershock sequence have a good power-law distribution in logarithmic coordinates. The research results provide a certain theoretical basis for the application of drilling pressure relief technology in southwestern Guizhou.

The Lannigou gold mine deposit is mainly composed of calcium-bearing sandstone and siltstone, and there are a lot of microdefects such as joints and cracks in the sandstone. The mesostructure of jointed sandstone makes a difference to the fracture process and mechanical properties. The RFPA2D software and Digital Image Processing Technology (DIP) were used to create a real microscopic structural numerical model of jointed sandstone with varied dip angle prefabricated cracks. A digital image-based rock microscopic scale fracture box dimension algorithm was established with MATLAB software. It is used to analyze the fractal characteristics of the acoustic emission field of unique prefabricated fractured sandstone. This study demonstrates that the mechanical parameter of jointed sandstone with different prefabricated cracks have manifest anisotropy, which includes elastic modulus and compressive strength. When the leaning angle of the cracks increases, they all increase linearly. There are three modes of starting-crack under uniaxial compression: from the peak of the prefabricated crack; from the middle of the prefabricated crack; and from the joint. Damage degree and rupture model are quantitatively represented by the fractal dimension. The more fractal dimensions there are, the more serious the damage, and the more complicated the rupture mode becomes. This research offers a novel method for investigating the evolution of rock microscopic scale fractures. This has to have engineering practical value for in-depth studies of rock fracture, instability, and failure, as well as the mechanisms that cause rock engineering disasters.

The traditional grading method of moyamoya disease represented by Suzuki grading system has always been the gold standard for most neurosurgeons in the diagnosis of moyamoya disease. However, in recent years, more and more studies have raised questions about Suzuki grading. The purpose of this study is to describe and summarize the questions raised about the Suzuki grading and reconsider its authority, using a questionnaire and literature review. The questionnaire showed that 73.61% of neurosurgeons had questioned the Suzuki grading, among which the main problems included "unclear boundaries between grades" and "inconsistent grading between the left and right cerebral hemispheres". From December 1969 to March 2021, 105 of the 773 references raised the same questions as in the questionnaire, and 27 of the 773 references raised different questions. Some of the questioned studies hope to take multiple imaging methods into consideration for grading of moyamoya disease, and some of the studies hope to include more quantifiable imaging indicators and establish a new grading system for moyamoya disease. In summary, the clinical utility of the Suzuki grading has been questioned by most neurosurgeons and some researchers, part of the research put forward some pertinent opinions.