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This study presents a systematic outcrop and subsurface study of fracture patterns variations in a complicated rock slope in an attempt to characterize rock heterogeneity on several dimensions. While the studies of outcrop fracture patterns have been so far focused on local variations, we propose a statistical analysis of global variations. The entire outcrop was partitioned into several subzones and the subzone-scale variability of fracture geometric properties (including orientation, density, and trace length) is analyzed. On this basis, the subsurface rock heterogeneity is characterized by 3D discrete fracture network (DFN) modeling for each structurally diverse subzone. Considering that complex site phenomena, such as vegetation and rockfalls, would affect the fracture expression to a certain way, data processing schemes are proposed aiming at their specific effects. The aim is to provide a set of systematic work flow for adequate characterization of rock heterogeneity in rock mass engineering constructions.

Although transition-metal sulfides have emerged recently as a type of promising candidate to serve as lithium-ion battery anodes, the chemical synthesis of transition metal-sulfide materials usually involves a complex operation process and is time-consuming. The natural transition metal-sulfide minerals are potential materials for lithium-ion battery electrodes because of their abundant reserves and cost savings of the synthesis process. The synthesis of nanosized transition metal-sulfide-based materials from natural bulk minerals remains challenging. In our work, we demonstrate that a composite of ~ 10–50-nm ZnS nanoparticles that are anchored on reduced graphene-oxide nanosheets can be synthesized by using bulk natural sphalerite in a simple, rapid and pollution-free microwave shock method. As anode electrode, this composite exhibited a high reversible specific capacity (~ 611 mAh g−1 at 0.1 C), good rate performance and good cycling stability. This work provides a route for the high-value utilization of natural minerals.

Rock masses are highly characterized by size effect due to the existence of complex discontinuities, which could be reflected by representative volume element (RVE). This study exemplified calculat...

This study takes sluice foundation rock mass in Datengxia Hydropower Station, China as an example to examine two-dimensional (2D) discrepancies in fracture geometric factors and connectivity between field-collected and stochastically modeled discrete fracture networks (DFNs). We discover that the trace lengths of field-collected and corresponding modeled DFNs diverge, especially with relatively large lengths. A new variable called minimum spacing sequence (MSS) is proposed, which lists minimum spacing between each fracture midpoint and all the other fracture midpoints. The probability density function curve of MSS shows that the fracture locations do not follow a homogeneous (Poisson) model. The following is performed to examine whether the differences will result in noticeable DFN application errors. The 2D fracture connectivity, which is calculated by depth-first search algorithm, is applied to quantify the discrepancies between field-collected and statistically modeled 2D DFNs. Results show that the statistically modeled DFNs have small clustered fracture path numbers and ratios but with considerably large maximum and average lengths for paths (or for paths longer than certain thresholds) owing to the concentration disadvantage and connection advantage of scattered fractures. We comprehensively compare different 2D DFNs (including field-collected DFN, totally modeled DFNs, DFNs with field fracture size, and DFNs with field fracture locations) and conclude that generating statistically modeled DFNs with identical connectivity features is extremely difficult. Mechanical means that consider connections among fractures are recommended for DFN applications.

In the present work, low-cost natural molybdenite was used to make a MoS2/N-doped graphene composite through coulombic attraction with the aid of (3-aminopropyl)-triethoxysilane and the electrochemical performance was greatly improved by solvent-free microwave irradiation for tens of seconds. The characterization results indicated that most (3-aminopropyl)-triethoxysilane can decompose and release N atoms to further improve the N-doping degree in NG during the microwave irradiation. In addition, the surface groups of N-doped graphene were removed and the particle size of MoS2 was greatly decreased after the microwave irradiation. As a result, the composite electrode prepared with microwave irradiation exhibited a better rate performance (1077.3 mA h g−1 at 0.1C and 638 mA h g−1 at 2C) than the sample prepared without microwave irradiation (1013.6 mA h g−1 at 0.1C and 459.1 mA h g−1 at 2C). Therefore, the present results suggest that solvent-free microwave irradiation is an effective way to improve the electrochemical properties of MoS2/N-doped graphene composite electrodes. This work also demonstrates that natural molybdenite is a promising low-cost anode material for lithium-ion batteries.

The incorporation of organic fluorescent dyes into inorganic matrixes could greatly improve the luminous properties of organic dyes. In this study, we investigated the effect of three different types of layered mineral clays on the luminous properties of lucigenin (bis-N-methylacridinium nitrate, BNMA). Attempts were made to fit the isothermal data using Langmuir and Freundlich equations. The adsorption of BNMA onto montmorillonite and kaolinite were fitted well by Langmuir isotherm equation while that of BNMA onto rectorite was fitted by Freundlich equation. The results indicated that the adsorptive behavior, which was resulted from the different layer structures, had a direct impact on the luminous properties of the composites.

Design and preparation of nanostructured conducting polymers (CPs) is a very important research direction for high performance CPs-based supercapacitors (SCs). With hollow structure, high surface area, tunable surface properties and abundant resources, natural halloysite is a promising template agent for preparing new nanotubular-structure CPs. Here, nanotubular-structure polyaniline was successfully synthesized using natural tubular halloysite as hard template. The obtained tubular polyaniline presents high specific capacitance at various current density as electrode material for supercapacitors. After a facile carbon coating, the carbon coated tubular polyaniline shows high specific capacitance of 654 F g−1 at the current density of 1 A g−1 and excellent electrochemical stability with capacitance retentions ∼87% after 10000 cycles. This work may prove the feasibility of preparing high performance CPs-based nanostructure electrode materials for SCs application based on inexpensive natural clay minerals.