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Weathered bedrock aquifer is the main water-filled aquifer for coal mining in Jurassic coalfields in northern Shaanxi. The regional prediction of the water richness of weathered bedrock aquifer is the key to mine water control. Taking the central and western part of Hongliulin Minefield as the research area, based on the analysis of the factors affecting the water-richness of the weathered bedrock, the thickness of the weathered bedrock, the core removal rate, the degree of weathering, the combination of lithology, the top elevation of the weathered bedrock and the sand base ratio are selected to use as the discriminant indexes, 41 groups of effective weathered bedrock borehole pumping test data in the study area are used as training samples and verification samples with a 3∶1 random allocation method to construct a water-rich Bayes discriminant analysis model. This model is used to predict the water richness category of weathered bedrock that has not been drilled for pumping test in the central and western part of Hongliulin Minefield, and the water richness prediction diagram of weathered bedrock is obtained. The results show that the overall water-rich water in the western first panel of the study area is relatively strong, and the spatial distribution of strong water-rich area is uneven. Most areas of the north second panel and the south second panel have relatively weak water richness, and the extremely weak water rich areas are distributed in the southeast. By comparing with the actual production of the working face water inflow and the location of the water outlet point, the prediction result of the water-rich zone is consistent with the actual situation.

The hydrochemical characteristics of groundwater in coal mining areas and its formation are of great significance to groundwater protection in mining areas and the identification of mine water inrush water sources. This paper takes the Quaternary aquifer, Cretaceous Luohe Formation, Jurassic Anding Formation and Zhiluo Formation aquifer groundwater as research objects in the Yushenfu Mining Area in northern Shaanxi. The chemical characteristics and formation of groundwater were analyzed by comprehensive use of statistical analysis, Piper's three-line diagram, isotope, Gibbs diagram and ion ratio relationship. The results show that the groundwater in this mining area is weakly alkaline fresh water. In the groundwater of quaternary, cretaceous Luohe Formation and Jurassic Zhiluo Formation （weathered bedrock）, the cation is mainly Ca2+, and the anion is mainly HCO3 −. In the groundwater of Jurassic Anding Formation, the cation is mainly K++Na+, and the anion is HCO3 −. In the groundwater of Jurassic Zhiluo Formation （normal bedrock）, the cation is mainly K++Na+, and the anion is mainly SO4 2−. TDS in the groundwater of each aquifer is significantly correlated with major ions. In the normal bedrock groundwater of the Luohe Formation and the Jurassic Zhiluo Formation, the spatial distribution of ions was quite different. Through isotope analysis and dissolution analysis, there is a hydraulic connection between the fourth series and the weathered bedrock aquifer of the Zhiluo Formation. The formation of main ions in groundwater in the study area is controlled by rock weathering, and the main ions are derived from the dissolution of carbonate, silicate, and sulfate minerals, and are affected by the alternating adsorption of K+, Na+, Ca2+, and Mg2+ cations. The results of this study can provide some reference for the protection and rational development and utilization of groundwater resources in the Yushenfu Mining Area.

In the paper, N1212 working face was taken as the research object, the law and mechanism of surface cracks in shallow coal seam mining were studied by means of field investigation, dynamic monitoring and numerical simulation. The results show that the development degree of surface cracks in shallow coal seam mining is high, mainly “step” cracks, and the in-plane cracks are distributed at parallel intervals with an interval distance of 8-15 m. The cracks have two kinds of activity characteristics: “opening-closing” and “only opening and disconnecting”; the stress evolution and failure in the overlying strata extend forward in the form of “arch”, and the overlying rock fissures and surface cracks are connected with each other; the advanced generation and activity characteristics of surface cracks are closely related to surface movement and deformation, surface “tension-compression” deformation transformation and slope slip. The research results can provide a theoretical basis for the prevention and control of ground collapse in coal mining areas.

The mining of Jurassic shallow coal seam in northern Shaanxi coal base is faced with a variety of water hazards, and the traditional coal mine water hazard assessment has some limitations, so it is necessary to carry out more detailed water hazard model and zoning research in this area. Taking 3-1 coal seam of Hongliulin Coal Mine as the research object, we calculate the development height of water flowing fractured zone in coal mining, draw the contour map of development height of water flowing fractured zone, and propose the water disaster mode division method based on coal mine water disaster types by using the mutual position relationship between each aquifer and water flowing height, and divide different water disaster modes in the study area. The results show that: according to the different water filled aquifers(bodies) in the study area, the water damage types can be divided into three main water damage modes: single aquifer water damage mode, composite aquifer water damage mode and ancient Zhiluo river water damage mode. According to different water filling sources, the single aquifer water damage model can be divided into roof burnt rock water damage type and roof weathered bedrock water damage type; the composite aquifer water damage model can be divided into roof burnt rock direct-loose layer indirect water damage type, roof weathered bedrock direct-loose layer direct water damage type, roof burnt rock direct-loose layer direct water damage type and roof weathered bedrock direct-loose layer direct water damage type water damage type. The single aquifer water damage model is mainly distributed in the water flowing fracture zone, roof weathered bedrock aquifer and the area with hidden burnt rock aquifer above the mining coal seam; the composite aquifer water damage model is distributed in the water flowing fracture zone breaking through weathered bedrock aquifer, directly or indirectly affecting the loose aquifer area; the ancient Zhiluo river water damage model is distributed in the ancient Zhiluo river and the ancient river terrace. According to the analysis of the risk of water inrush under different water damage modes, the type of burning rock water damage generally does not pose a great threat to coal mining, and the risk of water inrush is small. Roof weathered bedrock water damage model, roof composite water damage model and ancient Zhiluo river water damage model are highly water-rich in some areas, and may enter the underground through the water conduction fault zone, so there is a certain risk of water inrush.

Two-dimensional (2D) layer of water molecules has been observed in crystalline hydrate (C10H18N)3Fe(CN)6·17H2O (1). The layer is generated by interconnection of cube-like clusters by two oxygen atoms. On the other hand, this layer can also be viewed as fuzing bowl-shaped units by sharing edges. [ABSTRACT FROM AUTHOR]

Mesoporous silica, as a drug carrier, has become the new research focus in the field of nanodrug delivery system in recent years. In this study, Mn-doped mesoporous silicas are synthesized by template and in-situ doping method and physically characterized. The drug-loading performance of silica and its impact on drug release are studied. The Mn-doped mesoporous silicas show dendritic morphology (MDMS) with a loose wrinkle structure on the surface and a large number of pores. MDMS is used as a carrier to solve the problem of low water solubility of paclitaxel. In order to avoid leakage during drug transportation, the surface of Mn-doped mesoporous silica loaded with paclitaxel is coated with N-succinyl chitosan to construct a new type of nanodrug delivery system (MDMS-PTX-NSC). Compared to MDMS, MDMS-PTX-NSC shows an increase in particle size and smooth surface. The dissolution characteristics of manganese ions and swelling behavior of N-succinyl chitosan make MDMS-PTX-NSC delivery system exhibit a good pH-responsive release. And MDMS-PTX-NSC release curve can be well fitted by Ritger-Peppas equation. The cytotoxicity test shows that the MDMS-PTX-NSC has significant biocompatibility and enhanced cytotoxicity, which reveals that the MDMS-PTX-NSC is a promising nanodrug delivery system. [ABSTRACT FROM AUTHOR]

Cu-doped TiO2 film electrodes are synthesized via sol–gel technique and physically characterized. The Cu-doped TiO2 film electrodes is sensitized by tetrakis (4-carboxyphenyl) porphyrin and applied as a photoanode of a photoelectrochemical biofuel cell (PEBFC). The Cu/TiO2-based PEBFCs show a short-circuit current (Isc) of 75.9 μA, an open-circuit potential (Voc) of 912 mV, a maximum power density (Pmax) of 66.43 μW/cm2 and an overall energy conversion efficiency (η) of 2.16%, respectively. The PEBFCs indicate improved photoelectric performances comparing the TiO2-based PEBFC (Isc: 72.5 μA, Voc: 740 mV, Pmax: 35.34 μW/cm2, η: 1.52%). The Cu/TiO2-based PEBFCs also indicate a higher incident photon-to-collected electron conversion efficiency (IPCE), which is probably due that the doped copper reduces the band gap of a wide-gap TiO2 semiconductor as shown by ab initio band calculation. And the Cu/TiO2-based PEBFC can provide long electron lifetime and decrease electron–hole pair recombination rate, which is responsible for the better performance in the Cu/TiO2-based PEBFC than in the TiO2-based PEBFC. [ABSTRACT FROM AUTHOR]

Aiming at the high permeability or low pressure oil layers in Huabei oilfield, conventional well washing will cause more effluent invading stratum, and it will take a long time for water content rate back to normal value. In view of the above problems, hot wax cleaning technology of the hollow rod without cutting production was applied. After the improving of well washing check valve, selecting the matching washing equipment, optimizing hot washing parameters, the hollow sucker rod and matched well washing check valve were put down into the paraffin section below. The heat well washing water through the rod surface to heat and melt rod pipe junction wax. The wax is transported to the measuring station with the output liquid, and then wax cleaning is finished to maintain the oil wells. This technology of short time, less water consumption, no water recovery period and no pollution formation, is a new process of high efficiency and energy saving. [ABSTRACT FROM AUTHOR]

In order to effectively control the frequency and probability of the unsafe state of miners, this paper used qualitative research method of grounded theory to analyze 46 related documents and establishes 32 open codes, 11 axial codes, 3 selective codes. We use part of the open codes to establish an index system, and a questionnaire is issued, and safety experts are invited to score the three-level indicators. We use Matlab R2019a to process the data, determine the weight of factors affecting the unsafe state of miners through factor analysis, and determine the weight of factors affecting the unsafe state of miners. The results show that the unsafe state of miners is affected by three factors: individual factors, organizational management factors and environmental factors, of which individual factors account for the largest weight, and the changes in mental fatigue and muscle fatigue can greatly affect the unsafe state of miners. From this, this paper puts forward the countermeasures of shaping intrinsically safe employees, optimizing corporate organization and management, and creating a good working environment.

Objective: To establish a RP-HPLC method for determination of the content of ginsenoside Rg1 in the rabbits aqueous humor, blood and ocular tissues, which were given intragastric administration with the co-xueshuantong soft capsules. The drug concentration in rabbits at different times after oral administration has been determined and the pharmacokinetics characteristics has been researched., Method: The compound xueshuantong soft capsules were administrated to the healthy New Zealand rabbits by gavage (10 mg x kg(-1) per rabbit). The concentration of Ginseng Rg1 in aqueous humor, blood and ocular tissues at different time was determined by RP-HPLC., Result: RP-HPLC can be established for the determination of ginsenoside Rg1 in the rabbits aqueous humor, blood, ocular tissue. The calibration of curves was linear within the range of 7.60-152.0 mg x L(-1) (r = 0.999 6) for ginsenoside Rg1 in aqueous humor and the calibration of curves were linear within the range of 10.35-103, 50 mg x L(-1) (r = 0.999 8) for ginsenoside Rg1 in blood. Determination of the recovery rate to meet the requirements., Conclusion: The ginsenosides Rg1 could transmit the blood-ocular barrier into the eyes and reach a certain concentration. The research provides a theoretical and experimental basis for the systemic administration of compound Xueshuantong to treat eye diseases.