Rockburst mechanism and the law of energy accumulation and release in mining roadway: a case study

The rockburst dynamic disasters in the process of deep coal mining become more and more serious.Taking the rockburst occurred in the 23130 working face of Yuejin Coal Mine as the engineering background,we study the characteristics of mining stress feld around roadway,the plastic failure morphological characteristics of surrounding rock and the accumulation/release law of elastic energy before and after burst.An analysis model quantitatively describing the physical process of rockburst in the mining roadway is established,and the calculation method of dynamic release of elastic energy in the physical process of rockburst is educed.The mechanism of rockburst in mining roadway is revealed.The results show that an“L-shaped”stress concentration zone is formed within 100 m of the 23130 working face,and the principal stress ratio of the surrounding rock of the transportation roadway is 2.59–4.26.The change of the direction of the maximum principal stress has a signifcant efect on the burst appearance characteristics.The failure strength of diferent sections of the mining roadway is characterized by the elastic energy release value.With the increase of the working face distance,the elastic energy released by burst failure and the expansion variation of failure boundary radius show a nonlinear variation law that tends to decrease steadily after sharp fuctuation.The closer to the working face,the higher the burst risk.At a distance of 10 m from the working surface,the maximum principal stress reaches its maximum value.The butterfy-shaped failure system generated by the surrounding rock of the roadway has energy self-sustainability,and the elastic energy released by the sudden expansion of the butterfy leaf is enough to cause a burst damage of 1.9 magnitude.This work could provide theoretical support for the prediction and prevention of rockburst.

Several miRNAs derived from serum extracellular vesicles are potential biomarkers for early diagnosis and progression of Parkinson’s disease

Background:Blood-based test for predicting disease progression and early diagnosis of Parkinson’s disease(PD)is an unmet need in the clinic.The profiles of microRNAs(miRNAs)are regarded as potential diagnostic biomarkers for human diseases,whereas miRNAs in the periphery are susceptible to the influence of various components.MiRNAs enriched in serum extracellular vesicles(EVs)have demonstrated disease-specific advantages in diagnosis due to their high abundance,stability and resistance to degradation.This study was aimed to screen differentially expressed EV-derived miRNAs between healthy controls and PD patients to aid in diagnosis of PD.Methods:A total of 31 healthy controls and 72 patients with a diagnosis of PD at different Hoehn and Yahr stages in Tangdu Hospital were included.In total,185 differentially expressed miRNAs were obtained through RNA sequencing of serum EVs as well as edgeR and t-test analyses.Subsequently,the weighted gene co-expression network analysis(WGCNA)was utilized to identify the commonly expressed miRNAs in all stages of PD by constructing connections between modules,and specifically expressed miRNAs in each stage of PD by functional enrichment analysis.After aligning these miRNAs with PD-related miRNAs in Human miRNA Disease Database,the screened miRNAs were further validated by receiver operating characteristic(ROC)curves and quantitative real-time polymerase chain reaction(qRT-PCR)using peripheral blood EVs from 40 more participants.Results:WGCNA showed that 4 miRNAs were commonly associated with all stages of PD and 13 miRNAs were specifically associated with different stages of PD.Of the 17 obtained miRNAs,7 were validated by ROC curve analysis and 7 were verified in 40 more participants by qRT-PCR.Six miRNAs were verified by both methods,which included 2 miRNAs that were commonly expressed in all stages of PD and 4 miRNAs that were specifically expressed in different stages of PD.Conclusions:The 6 serum EV-derived miRNAs,hsa-miR-374a-5p,hsa-miR-374b-5p,hsa-miR-199a-3p,hsa-miR-28-5p,hsa-miR-22-5p and hsa-miR-151a-5p,may potentially be used as biomarkers for PD progression and for early diagnosis of PD in populations.