Fluidity and Strength of Loess-Based Quick Consolidated Backfill Material with One High-Water Content.

To study the flow and strength characteristics of loess-based backfill materials, orthogonal tests were used to design a cemented backfill material combining loess, high-water content materials, cement, and fly ash. By using the range, analysis of variance, and multi-variate regression analysis, influences of four key factors on the initial setting time, diffusivity, compressive strength, and shear strength of the backfill material were investigated. These four factors included the mass concentration of loess water (A), the content of high-water content materials (B), cement content (C), and content of fly ash (D). The results showed that the initial setting time, diffusivity, compressive strength, and shear strength of the backfill material were 13~33 min, 400~580 mm, 0.917-3.605 MPa, and 0.360-0.722 MPa, respectively, all distributed in wide ranges. For the initial setting time, the four factors were listed in descending order as A > D > B > C according to their influences; for diffusivity, the four factors were listed as A > B > C > D; for the compressive strength, the four factors were ranked as A > C > D > B; for the shear strength, the four factors were ranked such that A > C > D > B. With regard to the comprehensive index, the four factors were such that A > B > D > C. That is, the factors were listed in descending order as the mass concentration of loess water, cement content, the content of fly ash, and content of high-water content materials according to their significance in influencing characteristics of the loess-based backfill material. Comprehensive analysis indicated that the fluidity of the material was mainly influenced by the mass concentration of loess water, and the two were negatively correlated. The hydro-consolidation effect of materials with high-water contents accelerated material solidification. The strength of the backfill material was mainly influenced by the cement content while only slightly affected by contents of other materials. In this way, a prediction model for characteristic parameters, namely, fluidity and strength, of the loess-based backfill material under the action of various factors was established.

MiR-27 alleviates myocardial cell damage induced by hypoxia/reoxygenation via targeting TGFBR1 and inhibiting NF-κB pathway.

MiR-27 prevents atherosclerosis by inhibiting inflammatory responses induced by lipoprotein lipase. Overexpression of miR-27b attenuates angiotensin-induced atrial fibrosis. Nevertheless, studies have rarely investigated on the effect of miR-27 in cardiomyocyte injury. H9c2 cells were transfected with miR-27 mimic/inhibitor. Then the cell proliferation was tested by MTT assay and the cell apoptosis was detected by flow cytometry. The luciferase activity assay was utilized to analyze the relationship between miR-27 and TGFBR1. Quantificational real-time polymerase chain reaction and western blot were utilized to detect the cardiomyocyte differentiation marker and nuclear factor kappa B (NF-κB) pathway. Our outcomes demonstrated that miR-27 expression was downregulated cardiomyocyte injury subjected to hypoxia/reoxygenation (H/R). Additionally, overexpression of miR-27 could significantly alleviate cardiomyocyte injury by regulating cell activity and apoptosis. The luciferase activity assay confirmed that transforming growth factor ß receptor 1 (TGFBR1) is a direct hallmark of miR-27. Besides, overexpression of miR-27 promoted the expression of TGFBR1 in H/R model. After transfection with miR-27 mimic/inhibitor, the expression of NF-κB pathway-related proteins was decreased/increased. Taken together, our data manifested that miR-27 repressed cardiomyocyte injury induced by H/R via mediating TGFBR1 and inhibiting NF-κB signaling pathway. Furthermore, miR-27/ TGFBR1 might be utilized as hopeful biomarkers for myocardial ischemia diagnosis and treatment.

Analysis of the nonlinear dynamic response of guide rails for a suspended buffer.

Guide rails' nonlinear dynamic response to the collision process between gangues and the suspended buffer is the basis for its intensity examination and fatigue prediction. This paper established a numerical model for simulating the dynamic response of buffer's guide rails using Pro/E and Femap based on an analysis of the basic structural components of the suspended buffer. The effects of the gangues diameter and feeding rate on the guide rails' dynamic response were investigated, which were mainly revealed by a tension in guide rails. Simulation results showed that the tension in guide rails rapidly increased to a peak value after the suspended buffer was impacted by gangues, followed by a periodic vibration. The peak tension, maximum and minimum tensions within the periodic vibration were exponential functions of the gangues diameter. And they depended linearly on the feeding rate. The vibration frequency of the tension in guide rails was an exponential function of the gangues diameter but did not depend on the feeding rate. Based on the backfilling workface parameters used in D.Ping coal miner's 15601 working panel, the feeding rate of 500 t/h was selected. The diameter of the crushed gangues was selected to be 50 mm based on the strength of guide rails. Their expected service life is 54.2 years. Finally, an industrial test was performed in D.Ping coal miner's 15601 working panel and the guide rails operated steadily. The measured vibration parameters of the tension in guide rails agree well with that of numerical predictions, which verified the reliability of the numerical model to some extent.