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A rockfall is a typical dynamic problem of a discontinuous block system originating from a dangerous rock mass and always presents serious geo-hazards along highway slopes in mountainous areas. This study aims to investigate the failure mechanisms and movement characteristics of rockfalls through a three-dimensional discontinuous deformation analysis (3D DDA) method and attempts to comprehensively examine the complicated kinematic process of rockfall disasters. In terms of the initial failure and post-movement characteristics (i.e., motion trajectory and kinetic energy) of a rockfall, the effectiveness of 3D DDA is verified by comparing its results with those of laboratory experiments. Taking the K4580 typical high-steep slope undergoing rockfalls along the G318 national highway in Tibet as an example, the initiation and failure of a single boulder and a large-scale rock mass at the source area were simulated by 3D DDA. Then, the movement characteristics of the boulder and massive collapsing rocks along the slopes of different geometrical characteristics, i.e., the slopes before the landslide and after the shallow and deep landslides, were studied. The results show that the 3D DDA has significant advantages in analysing the failure mechanisms of slope rockfalls and can satisfactorily simulate the spatial movement (e.g., lateral deviation and deflection) of blocks by considering the 3D geometry of the slopes and blocks. The 3D DDA numerical simulation can predict the movement range, deposition position, and affected area of rockfall disasters, which can provide a basis for formulating disaster prevention countermeasures in actual projects. [ABSTRACT FROM AUTHOR]

Abstract Eight new triterpenoids, ganoleucoins T-Z(1 – 3 , 5 – 8), and AA (9), together with eleven known triterpenes were isolated and identified from the wild fruiting bodies of the medicinal mushroom Ganoderma leucocontextum. The structures of new compounds were determined on the basis of NMR and MS spectral analysis. The inhibitory effects of 1–9 on HMG-CoA reductase were tested in vitro. Compounds 1 , 7 and 8 showed significant HMG-CoA reductase inhibition with IC 50 values of 10.2, 9.72 and 8.68 μM, respectively. The other isolated compounds presented relatively weak inhibitory activity with IC 50 values >100 μM. Preliminary structure-activity relationship analysis showed that the HMG moiety in 7 and 8 contributed greatly to their inhibitory activity against HMG-CoA reductase. This work further demonstrates the mushroom G. leucocontextum to be valuable herbal medicine that deserves deep investigation. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Rockfall is a common geological disaster in rock slope projects. An understanding of the motion processes and characteristics of the rock blocks originating from a rockfall is of profound importance for comprehending the mechanism(s) of rockfall disasters. In this study, a field experimental system comprising binocular stereovision was developed for examining rockfalls, and a series of experiments on rockfall motion characteristics were performed on slopes near an abandoned section of the G318 national highway in Tibet, China. The indices of motion characteristics such as the lateral displacement, staying position, jumping height, and kinetic energy evolution of the blocks under different work conditions (e.g. different masses, shapes, falling heights, falling angles, and different geometrical characteristics in the slopes) were investigated by combining experiments with a three-dimensional discontinuous deformation analysis (3D DDA) method. The results show that the field experimental system has high accuracy in monitoring the block movement processes. The 3D DDA results agree well with those from the experiments, and the evolutions of the motion characteristics of the rockfall under different conditions are quantitatively obtained. Furthermore, the results provide insight into the laws of rockfall movements and dynamic impact processes, and lay a foundation for the design of rockfall protection measures and engineering approaches for disaster prevention and mitigation. [ABSTRACT FROM AUTHOR]

Hypoxia-induced pulmonary hypertension (HPH) is a severe condition associated with significant morbidity and mortality in people living at high altitude. Tsantan Sumtang, a traditional Tibetan medicine, has been routinely used for the treatment of cardiopyretic disease, as well as stenocardia. Interestingly, our previous research found that Tsantan Sumtang improved HPH in rats maintaining in a hypobaric chamber. We performed a series of experiments to test the indexes of vasoconstriction and vascular remodeling, the key pathophysiological characteristics of HPH. Our results showed that Tsantan Sumtang relaxed noradrenaline (NE)-precontracted rat pulmonary artery rings in a concentration-dependent manner in vitro. The PGI2-cAMP (prostaglandin I2-cyclic adenosine monophosphate) pathway, NO-cGMP (nitric oxide-cyclic guanosine monophosphate) pathway, and the opening of K+ channels (inward rectifier K+ channels, large conductance Ca2+-activated K+ channels, and voltage-dependent K+ channels) might play major roles in the vasorelaxation effect. In vivo, the administration of Tsantan Sumtang resulted in a substantial decrease in the rat mean pulmonary artery pressure (mPAP) and the right ventricular hypertrophy index (RVHI). The reduction of thickness of small pulmonary arterial wall and the WT% (the ratio of the vascular wall thickness to the vascular diameter) were observed. The smooth muscle muscularization of the arterials was alleviated by Tsantan Sumtang treatment at the same time. Tsantan Sumtang also reduced remodeling of pulmonary arterioles by suppressing the expression of proliferating cell nuclear antigen (PCNA), α-smooth muscle actin (α-SMA), cyclin D1, and cyclin-dependent kinase 4 (CDK4) through inhibition of p27Kip1 degradation. Therefore, Tsantan Sumtang could be applied as a preventative medication for HPH, which would be a new use for this traditional medicine. [ABSTRACT FROM AUTHOR]