Longitudinal torsional vibrations of the chain drive system of mine scraper conveyor.

To deeply analyse the dynamic characteristics of the scraper conveyor during operation, the mechanical characteristics of the coupled longitudinal and torsional vibrational modes under excitation by cargo loading are studied. Based on the Kelvin‒Voigt model and the point-by-point tension method, a model of the coupled longitudinal and torsional vibrations of the scraper chain drive system is established. Then the functional program is constructed and the numerical simulation is carried out. Finally, the correctness of the model is verified by comparison with experiments. The research results reveal the torsional vibration characteristics of the scraper chain drive system under two different working conditions, light load and medium load, and determine the influence area of the torsional vibration of the scraper. The results of this analysis provide a theoretical basis for the subsequent optimization of the scraper parameters, the prediction of scraper chain drive system failure, and the calculation to give an early warning before failure occurs.

Modeling and characteristic analysis of roadway profile under the influence of multiple factors.

Considering that the movement trajectory of roadheader cutting head directly affects the surface morphology characteristics of roadway forming, the creation mechanism of roadway contour obtained by cutting head cutting roadway is analyzed. The robot kinematics analysis method was used to determine the coordinates of the roadheader cutting head in the roadway space coordinate system, and the mathematical model of the cutting head cutting the roadway contour was constructed. Through numerical calculation, the differences of roadway morphology characteristics formed by three different types of cutting heads are analyzed. The orthogonal experiment was designed, and the regression equation under multiple factors was solved with the experimental results. The influence of cutting feed rate, cutting Angle, cutting head radius and cutting head cone Angle on the morphology characteristics of cutting surface was analyzed by regression calculation and theoretical calculation. The research results show that the roadway surface obtained by "spherical crown + cylinder" cutting head is the most uneven, and the roadway surface obtained by "spherical crown + cone + cylinder" cutting head is the most flat. With the decrease of cutting lifting Angle, cutting feed, cutting head cone Angle and the increase of cutting head crown radius, the smoothness of roadway obtained by cutting is higher.

[Corrigendum] NORAD regulates epithelial­mesenchymal transition of non­small cell lung cancer cells via miR­422a.

Following the publication of this paper, the authors have realized that they overlooked indicating that Zhikun Chen and Qin Che contributed equally to this work. Therefore, the affiliations for this paper should have been written as follows:  Zhikun Chen1*, Qin Che2* and Chunxue Xie3. Departments of 1Emergency, 2Infectious Diseases and 3General Practice, Jingmen No. 1 People's Hospital, Jingmen, Hubei 448000, P.R. China. *Contributed equally. The authors confirm that there are no further errors in the study, and all the authors agree to this correction. The authors regret their oversight, and apologize for any inconvenience caused. [the original article was published in Molecular Medicine Reports 23: Article no. 111, 2021; DOI: 10.3892/mmr.2020.11750].

NORAD regulates epithelial­mesenchymal transition of non­small cell lung cancer cells via miR­422a.

The poor prognosis of non­small cell lung cancer (NSCLC) is related to epithelial­mesenchymal transition (EMT). Recent studies demonstrated that non­coding RNA activated by DNA damage (NORAD) displays a carcinogenic effect and targets microRNA (miR)­422a, which may be involved in tumor cell migration and invasion. The aim of the present study was to investigate the effect of NORAD on NSCLC cell EMT and the underlying mechanism. Reverse transcription­quantitative PCR and western blotting were performed to detect the expression levels of long non­coding RNAs, miRNAs and mRNAs. Cell viability, migration and invasion were detected by conducting Cell Counting Kit­8, wound healing and Transwell assays, respectively. The target of NORAD was predicted using starBase and further confirmed by conducting a dual­luciferase reporter assay. The results indicated that NORAD expression was significantly increased in lung cancer tissues and cells compared with adjacent healthy tissues and cells. Compared with the control groups, NORAD overexpression promoted SK­MES­1 cell viability, migration and invasion, whereas NORAD knockdown resulted in the opposite effects in A549 cells. Moreover, miR­422a, which was predicted to be a target of NORAD, displayed lower expression levels in lung cancer tissues compared with adjacent healthy tissues. In addition, miR­422a overexpression partially reversed NORAD overexpression­induced increases in SK­MES­1 cell viability, migration, invasion and EMT. In addition, miR­422a knockdown partially reversed the effects of NORAD knockdown. The present study suggested that NORAD regulated lung cancer cell EMT by regulating the expression of miR­422a, providing a potential therapeutic target for the intervention of the development of NSCLC.