Effects of lateral cyclic loading on compression behaviours of granular waste rocks for backfilling to reduce environmental pollution.

Granular waste rocks filled in goaf can replace coal seams to support roofs, thus reducing the extent of overlying strata movement, and thus reducing the environment damage caused by coal mining. To better to control the compression-induced deformation (CID) of waste rocks for backfill (WRBs), a loose material, it is feasible to apply lateral cyclic loads on granular waste rocks in advance. In order to study the effect of lateral cyclic loading on granular waste rocks, by utilising pre-lateral cyclic loading and axial loading, the deformation of granular waste rocks under load was tested on a compression simulation experimental platform for solid backfill materials. Furthermore, the changes in displacement, stress and mass of granular waste rocks during lateral cyclic loading were attained. The test results showed that (1) the loading stress progressively increased with the growth of the loading displacement, in which the rising process was divided into three stages according to the rate of loading. (2) With the increase in number of loading cycles, the rate of increase of stress in stage I increased and the stress reached increasingly higher levels; at the same time, stage II was gradually shortened. Eventually, only a single stage prevailed as the stress rapidly reached its preset maximum value, and the final displacement of the samples gradually declined. (3) The axial stress-strain curves of the samples exhibited a quasi-exponential relationship. Through lateral cyclic loading, the relative density of WRBs was significantly improved, and their deformation resistance was strengthened. (4) During backfill mining, lateral cyclic loads were applied to granular waste rocks, which improved the bearing capacity thereof and reduced strata movement and surface subsidence. This is beneficial to the protection of the surface environment and surrounding buildings.

Transcriptome and DNA methylation analysis reveals molecular mechanisms underlying intrahepatic cholangiocarcinoma progression.

Intrahepatic cholangiocarcinoma (iCCA) is an aggressive malignancy with increasing incidence. It has been suggested that DNA methylation drives cancer development. However, the molecular mechanisms underlying iCCA progression and the roles of DNA methylation still remain elusive. In this study, weighted correlation networks were constructed to identify gene modules and hub genes associated with the tumour stage. We identified 12 gene modules, two of which were significantly positively or negatively related to the tumour stage， respectively. Key hub genes SLC2A1, CDH3 and EFHD2 showed increased expression across the tumour stage and were correlated with poor survival, whereas decrease of FAM171A1, ONECUT1 and PHYHIPL was correlated with better survival. Pathway analysis revealed hedgehog pathway was activated in CDH3 up-regulated tumours, and chromosome separation was elevated in tumours expressing high EFHD2. JAK-STAT pathway was overrepresented in ONECUT1 down-regulated tumours, whereas Rho GTPases-formins signalling was activated in PHYHIPL down-regulated tumours. Finally, significant negative associations between expression of EFHD2, PHYHIPL and promoter DNA methylation were detected, and alterations of DNA methylation were correlated with tumour survival. In summary, we identified key genes and pathways that may participate in progression of iCCA and proposed putative roles of DNA methylation in iCCA.

Prediction of compression and deformation behaviours of gangue backfill materials under multi-factor coupling effects for strata control and pollution reduction.

Coal mining causes serious ecological and environmental damage. The crushed gangue is backfilled into underground goaf, which not only inhibits mining-induced subsidence but also reduces accumulation of waste on the ground: however, the effects of backfilling with gangue backfill materials in goaf are affected by a combination of multiple factors. To predict compression-induced deformation (CID) of gangue backfill materials, key factors influencing compression and deformation characteristics of gangue backfill materials in an underground confined space (lithology, particle size distribution, lateral stress and lateral loading times) were determined. Moreover, two key factors, namely, lithology and particle size distribution of gangue backfill materials, were quantified. Based on orthogonal test design, the compression characteristics of gangue backfill materials were measured under different stress levels and coupling effects of the four key factors by utilising a self-made bidirectional loading test system for bulk materials. Furthermore, through regression, the relationships of the four key factors and axial strain were determined as well as undetermined parameters in axial stress-axial strain equations and axial stress. Based on this, an equation for predicting stress-strain relationship during compression-induced deformation of gangue backfill materials under multi-factor coupling effects was established. Comparison with the orthogonal test results shows that this equation can predict compression-induced deformation of gangue backfill materials in goaf. This is beneficial to providing a basis for predicting strata movement and surface subsidence and guidance for designing backfilling process, thus protecting the surface environment.

Sensitivity analysis of key factors influencing compression-induced deformation of waste rocks for backfilling to reduce environmental pollution.

As solid wastes are generated during coal mining, waste rocks can be backfilled into goaf so as to reduce geological hazards and environmental damage caused by coal mining; however, under different stress regimes, the sensitivities of factors influencing compression-induced deformation (CID) of waste rocks for backfilling (WRBs) are different. In order to control the compression-induced deformation of waste rocks for backfilling more efficiently, compression characteristics of waste rocks for backfilling under four different stress levels were tested by using a homemade loading test system for granular materials based on an orthogonal experiment. The influences of lithology, particle size distribution (PSD), lateral stress, and number of lateral loading cycles on compression-induced deformation of waste rocks for backfilling and sensitivities ranks of the four factors were analysed. The test results showed that: (1) under an axial stress of less than 10 MPa, lateral stress was considered the main factor influencing compression-induced deformation of waste rocks for backfilling; when the axial stress ranged from 10 to 20 MPa, particle size distribution was the main influencing factor; (2) under four different axial stress levels, the optimal combination of influencing factors is sandstone, a particle size distribution from 0 to 10 mm, 3 MPa lateral stress, and 7 lateral loading cycles; (3) to control the compression-induced deformation of waste rocks for backfilling, it was necessary to optimise the lateral stress under an axial stress of less than 10 MPa; while the axial stress was between 10 and 20 MPa, it was essential to optimise the particle size distribution.