Experimental Investigation of Flow Control Technology for Grouting and Blocking of Flowing Water in Karst Conduits

Dongdong Pan,Zehua Bu,Haiyan Li,Zhenhao Xu,Jie Liu 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.8

Aiming at the grouting treatment in karst conduits with large flow and high velocity, we developed a simulation experiment system for conduit-type grouting blocking and investigated the blocking mechanism of flowing water grouting under the condition of flow control. Firstly, we studied the effect of flow control in conduit by controlling the opening of outlet valve and analyzed the variation law of velocity and pressure in conduits under different water heads, conduit diameters and valve opening quantitatively. Secondly, we conducted experiments of flowing water grouting under different flow control conditions, and revealed the influence law of flow control for flowing water grouting. The results show that: 1) with the increase of the intensity of flow control, the pressure in conduit increased gradually, and the velocity of flowing water decreased gradually. 2) When the volume ratio of water and cement was 1.2:1, the volume ratio of cement and sodium silicate was 2:1, the grouting volume was 540 L/h, and the flowing water velocity was 0.15 m/s, flowing water blocking under the condition of flow control achieved the optimal effect. 3) With flow control, the slurry deposition thickness increased more than 50% compared with no flow control; besides, the slurry retention rate increased, and the blocking effect significantly improved. The technology has been successfully applied in the grouting treatment project of China Resources Cement (Pingnan) Limestone Mine. And main water inflow points in the mine were blocked with an total amount of ~210,200 m3/d water reduction. This study provided some theoretical guidance and reference experience for treatment engineering of water inflow in karst area.

Effect of Mn Modification on Microstructure and Mechanical Properties of Magnesium Alloy with Low Gd Content

Dongdong Gu,Jian Peng,Jiawen Wang,Fusheng Pan 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.6

The evolution of microstructure and mechanical properties of the dilute Mg–Gd alloy with Mn modification were investigatedsystematically in this paper. The results show that the combination of Mn and different processing states could adjust thesolid solubility of Gd in the Mg matrix, thereby changing the morphology of the second phases and improving the propertiesof the alloy. With the addition of 0.8 wt% Mn into the Mg–4Gd alloy, the atomic utilization ratio of Gd atoms decreasesfrom 61.5 to 51.8% during the water-cooling casting process, but it increases from 73.8 to 81.0% during homogenizationtreatment and increases from 72.3 to 84.1% during hot extrusion. Thus, the mean diameter of granular phases of the Mg–4Gd alloy is larger than that of Mg–4Gd–0.8Mn alloy after the isothermal heat treatment. The Mn addition has little effecton the Hall–Petch constant KYand KHof Mg–4Gd alloy, but improves the σ0 value significantly due to the increase of theatomic utilization ratio of Gd atoms. Mn element can improve the mechanical properties of Mg–4Gd alloy, and the increaseof yield strength and ductility of as-extruded Mg–4Gd–0.8Mn alloy is mainly attributed to grain refinement and the decreaseof the texture intensity.

Aptamers against ManLAM of Mycobacterium tuberculosis inhibits virulent Mycobacterium tuberculosis infection in mice and rhesus monkeys

Qin Pan,Qilong Wang,Fengling Luo,Min Li,Xianru Xia Dongdong Shi,Xiao-Lian Zhang 한국당과학회 2012 한국당과학회 학술대회 Vol.2012 No.1

Tuberculosis (TB) has been a major world-wide cause of death for centuries. One-third of the world’s population is infected with Mycobacterium tuberculosis (M.tb), the etiologic agent of TB. The development of potent new anti-TB drugs is urgently needed. The major M.tb surface lipoglycans, mannose-capped Lipoarabinomannan (ManLAM) had immunosuppressive effects during M.tb infection. In this study, aptamer ZXL1 which specifically bound to ManLAM from the virulent strain M.tb H37Rv was screened out by Systematic Evolution of Ligands by EXponential enrichment (SELEX). The binding affinity of ZXL1 to ManLAM was measured as 8.907X10-8 M of quilibrium dissociation constant (Kd) value by surface plasmon resonance (SPR) analysis. We found that aptamer ZXL1 prevented the ManLAM-induced immunosuppressive effects on DCs and inhibited M. tb entry into macrophages. More importantly, we found that single injection of aptamer ZXL1 significantly prolonged the survival rate of infected mice, and prevent the infected rhesus monkeys from weight loss. The Bacterial numbers were significantly lower in the lungs and spleens in ZXL1-treated groups. These results suggest that aptamer ZXL1 can be used as antimycobacterial agent or as TB vaccine adjuvent.

An Integrated Evaluation Method for the Grouting Effect in Karst Areas

Qing Jin,Zehua Bu,Dongdong Pan,Haiyan Li,Zhaofeng Li,Yichi Zhang 대한토목학회 2021 KSCE Journal of Civil Engineering Vol.25 No.8

Our proposed integrated evaluation method for the grouting effect in karst areas is based on the cloud model (CM), the analytic hierarchical process (AHP), and a fuzzy comprehensive evaluation system. Our method fully considers the fuzziness and randomness of the evaluation indices, and bridges the gap between qualitative information and a quantitative evaluation value. The evaluation index system for the grouting effect is established by integrating metrics related to the construction technology, apparent parameters, and observational data from inspection holes and geophysical exploration techniques. First, the weight of each index is calculated using the AHP, which has been modified by the CM. Then, we calculate the cloud model membership degree for each index. Finally, we determine the comprehensive evaluation level by examining the similarity measures between the various cloud models. In this case study, we use our integrated method to evaluate the initial results of the grouting treatment project in the China Resources Cement (Pingnan) Limestone Mine. Our results are validated by subsequent monitoring results for this project. This study provides valuable insight into the treatment of water inflow in karst areas.

Small molecule natural compound agonist of SIRT3 as a therapeutic target for the treatment of intervertebral disc degeneration

Jianle Wang,Majid Nisar,Chongan Huang,Xiangxiang Pan,Dongdong Lin,Gang Zheng,Haiming Jin,Deheng Chen,Naifeng Tian,Qianyu Huang,Yue Duan,Yingzhao Yan,Ke Wang,Congcong Wu,Jianing Hu,Xiaolei Zhang,Xiangy 생화학분자생물학회 2018 Experimental and molecular medicine Vol.50 No.-

Oxidative stress-induced mitochondrial dysfunction is implicated in the pathogenesis of intervertebral disc degeneration (IVDD). Sirtuin 3 (SIRT3), a sirtuin family protein located in mitochondria, is essential for mitochondrial homeostasis; however, the role of SIRT3 in the process of IVDD has remained elusive. Here, we explored the expression of SIRT3 in IVDD in vivo and in vitro; we also explored the role of SIRT3 in senescence, apoptosis, and mitochondrial homeostasis under oxidative stress. We subsequently activated SIRT3 using honokiol to evaluate its therapeutic potential for IVDD. We assessed SIRT3 expression in degenerative nucleus pulposus (NP) tissues and oxidative stressinduced nucleus pulposus cells (NPCs). SIRT3 was knocked down by lentivirus and activated by honokiol to determine its role in oxidative stress-induced NPCs. The mechanism by which honokiol affected SIRT3 regulation was investigated in vitro, and the therapeutic potential of honokiol was assessed in vitro and in vivo. We found that the expression of SIRT3 decreased with IVDD, and SIRT3 knockdown reduced the tolerance of NPCs to oxidative stress. Honokiol (10 μM) improved the viability of NPCs under oxidative stress and promoted their properties of anti-oxidation, mitochondrial dynamics and mitophagy in a SIRT3-dependent manner. Furthermore, honokiol activated SIRT3 through the AMPKPGC- 1α signaling pathway. Moreover, honokiol treatment ameliorated IVDD in rats. Our study indicated that SIRT3 is involved in IVDD and showed the potential of the SIRT3 agonist honokiol for the treatment of IVDD.