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Study on Stabilit of Surrounding Rock in Deep Tunnel and It’s Support Design in Donghai Mine
JIN Zhupeng,ZHANG junwen,LI yulin 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.7
In order to control the deformation of surrounding rock in deep mine and study the corresponding patterns, the determination of its mechanics parameters and property, numerical simulation and the design of support scheme on the surrounding rock in fifth mining area of Donghai mine are conductive to the study of effective control of deformation and failure. By analyzing the characteristics of deformation and failure of surrounding rock, its regularity and corresponding reasons are finally found—— high stress make rock soft and lead to the large deformation of surrounding rock, which inevitably contribute to the broken roof and heaved floor. In addition, based on the numerical simulation, we further analyze the stress distribution and deformation characteristics of surrounding rock and proposed the anchor- injection - net – cable, the double support scheme. We also came up with the whole sealing and coordinated supporter for the fracturing roadway of large deformation, especially in the intersection roadways, witch undoubtedly is beneficial to the research of deformation mechanism and control of surrounding rock in deep mine.
Acteoside reduces testosterone by inhibiting cAMP, p450scc, and StAR in rat Leydig cells
Shuqiang Liu,Junwen Zhang,Weixuan Li,Tianxiang Zhang,Defu Hu 대한독성 유전단백체 학회 2015 Molecular & cellular toxicology Vol.11 No.1
The present study investigated the in vivo and in vitro effects of acteoside on testosterone production in Sprague-Dawley (SD) rats. The in vivo experiment revealed that acteoside reduced the testosterone level in serum significantly (P⁄0.05). The in vitro experiment also illustrated that acteoside significantly reduced testosterone production in SD rat Leydig cells in primary culture (P⁄0.05). Enzyme-linked immunosorbent assay results demonstrated that acteoside significantly reduced the cyclic adenosine 3′, 5′-monophosphate (cAMP) level (P⁄0.05), and Western blot analysis showed that acteoside significantly reduced cholesterol side-chain cleavage enzyme (p450scc) and steroidogenic acute regulatory (StAR) expression (P⁄ 0.05). Hoechst 33342 staining and Western blotting showed that acteoside did not induce apoptosis in Leydig cells. Together, these results suggest that the acteoside-induced reduction in testosterone production in rat may be at least partially due to down-regulation of cAMP, p450scc, and StAR, but not apoptosis.
Sun Xiang,Zhang Bo,Xu Guangjian,Chen Junwen,Shang Yongpeng,Lin Zhiwei,Yu Zhijian,Zheng Jinxin,Bai Bing 대한진단검사의학회 2021 Annals of Laboratory Medicine Vol.41 No.3
Background: Tigecycline, eravacycline, and omadacycline are recently developed tetracyclines. Susceptibility of microbes to these tetracyclines and their molecular mechanisms have not been well elucidated. We investigated the susceptibility of Moraxella catarrhalis to tigecycline, eravacycline, and omadacycline and its resistance mechanisms against these tetracyclines. Methods: A total of 207 non-duplicate M. catarrhalis isolates were collected from different inpatients. The minimum inhibitory concentrations (MICs) of the tetracyclines were determined by broth microdilution. Tigecycline-, eravacycline-, or omadacycline-resistant isolates were induced under in vitro pressure. The tet genes and mutations in the 16S rRNA was detected by PCR and sequencing. Results: Eravacycline had a lower MIC50 (0.06 mg/L) than tigecycline (0.125 mg/L) or omadacycline (0.125 mg/L) against M. catarrhalis isolates. We found that 136 isolates (65.7%) had the tetB gene, and 15 (7.2%) isolates were positive for tetL; however, their presence was not correlated with high tigecycline, eravacycline, or omadacycline (≥1 mg/L) MICs. Compared with the initial MIC after 160 days of induction, the MICs of tigecycline or eravacycline against three M. catarrhalis isolates increased ≥eight-fold, while those of omadacycline against two M. catarrhalis isolates increased 64-fold. Mutations in the 16S rRNA genes (C1036T and/or G460A) were observed in omadacycline-induced resistant isolates, and increased RR (the genes encoding 16SrRNA (four copies, RR1-RR4) copy number of 16S rRNA genes with mutations was associated with increased resistance to omadacycline. Conclusions: Tigecycline, eravacycline, and omadacycline exhibited robust antimicrobial effects against M. catarrhalis. Mutations in the 16S rRNA genes contributed to omadacycline resistance in M. catarrhalis.
Wenming Jiang,Guangyu Li,Feng Guan,Junwen Zhu,Dongping Zhang,Zitian Fan 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.4
A novel method named lost foam casting (LFC) process combined with layered extrusion forming (LEF) technology wasproposed to prepare the Al2O3/AZ91D Mg interpenetrating composites, and the microstructural characteristics, thermalexpansion performance and wear resistance of the Al2O3/AZ91D interpenetrating composites were investigated in this work. The results indicated that a superior bonding between AZ91D magnesium alloy and Al2O3porous ceramic was achieved. The Al2O3/AZ91D interpenetrating composites exhibited obvious improvements in the thermal expansion performance andthe wear resistance compared to the AZ91D alloy. Therefore, the LFC process combined with the LEF technology providesa promising method for the preparation of the Al2O3/AZ91D interpenetrating composites.
Jianhang Chen,Kangming Tao,Banquan Zeng,Lei Liu,Hongbao Zhao,Junwen Zhang,Danqi Li 한국콘크리트학회 2023 International Journal of Concrete Structures and M Vol.17 No.1
A better understanding of the tensile performance and tensile failure mechanism of cement paste is significant in preventing rock reinforcement failure. Therefore, this paper aims to reveal the tensile performance and failure mechanism of a modified Portland cement: Stratabinder HS cement. To achieve this objective, the split tensile test was conducted on specimens followed by simulating the failure mechanism numerically. The results indicated that the water–cement rate significantly influenced the tensile performance of the cement paste. When the water–cement rate increased from 0.35 to 0.42, the tensile strength declined from 1.9 MPa to 1.5 MPa. It was also observed that vertical tensile failure constantly occurred regardless of the water–cement rate. During the testing process, tensile cracks and shear cracks occurred. The increasing rate in the number of specimen cracks was dependent on the tensile stress state. Before the tensile stress reached the peak, the crack quantity increased slightly. After the peak, the crack quantity increased dramatically. During the vertical loading process, horizontal tensile stress occurred in the specimen. This horizontal tensile stress zone showed a diamond shape. The higher the tensile stress is, the larger the area of the horizontal tensile stress zone. When the tensile strength was reached, horizontal tensile stress mainly concentrated at the vertical centre of the specimen. This finally led to tensile failure of the specimen. This paper indicated that the water–cement rate was the key factor in evaluating the tensile strength of the Stratabinder HS cement.