New Model for Predicting Instantaneous Cutting Rate of Axial-type Roadheaders

Qianqian Zhang,Zhennan Han,Mengqi Zhang,Jianguang Zhang 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.1

Roadheaders are mechanical excavators which have been extensively used in tunneling, mining and civil engineering works. Performance prediction of the roadheader is major factor in determining the economy of an underground excavation project. In this study, a new model for predicting the Instantaneous Cutting Rate (ICR) has been developed. The performance of EBZ260W axialtype roadheader has been evaluated in the laboratory artificial rock cutting tests and in the tunneling field tests. Using the model, the processes of the artificial rock cutting in the laboratory tests have also been simulated. The predicted average ICRs in the laboratory tests, and in the simulations, together with the measured average ICRs in the laboratory tests and in the field tests are presented in this paper. The comparison of the predicted and measured ICRs shows that the relative error is within 5%. There are also reasonable agreements and strong correlations between the model and tests results. The new ICR prediction model is also supported by the empirical prediction formulas developed by other researchers. Hence, the model can be used to reliably predict the ICR for axial-type roadheaders.

10-m long slim sandpack experiments to investigate gel system transport behavior in porous media

Jianguang Wei,Xin Zhang,Jiangtao Li,Runnan Zhou,Songze Liu 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.10

Understanding the transport behavior of a gel system in porous media is of great significance in enhancing oil recovery (EOR) for high water cut oil reservoirs. However, the length of the experiment models (sandpack or core sample) in current studies is usually in the range of centimeter scale, which is too short to track the full movement path of gel particles. In this work, 10-m long slim sandpacks were adopted to conduct gel flooding experiments. The pressure and polymer concentration distribution along the sandpack was tracked, and scanning electron microscope (SEM) technique was employed to observe the pore morphology after the gel flooding. The results show that the movement of polymer particles is usually within 7m away from the inlet due to the adsorption and retention in the porous medium. For 0.4 PV injection cases, SEM images show that the pore morphology at the inlet region exhibits a stable polymer network, while the network structure disappears at the outlet, along with the decrease of fluid viscosity from 620.1mPa·s to 1.2mPa·s. However, we can still find the stringy state polymer after 5m movement and the viscosity is 584.0mPa·s for 1 PV gel injection cases. Four characterization parameters, including equivalent viscosity, breakthrough pressure gradient, dimensionless gelation gradient, and plugging ratio, were proposed to quantitatively characterize the performance of gel flooding. In addition, empirical models were also obtained to predict the four parameters through multi-parameters fitting, and these models facilitate the characterization of the gel flooding performance. This is the first work, to the best of the authors’ knowledge, using long slim sandpack (10m) to experimentally study gel system transport in porous media, which provides theoretical implications in enhancing oil recovery.

Study on Axial Compression Behavior of Cross-Shaped and L-Shaped Multi-cavity Concrete-Filled Steel Tube Special Shaped Column

Hongbo Li,Yufei Tong,Jianguang Yin,Hubiao Zhang,Changyu Yan 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.1

Multi-cavity concrete-fi lled steel tube special shaped column (CFSTSSC) combines the excellent characteristics of multicavity steel tube and core concrete. CFSTSSC has the advantages of high bearing capacity, good ductility, and strong energy dissipation capacity. At present, accurate calculation methods for these kinds of structures are limited and research into crossshaped and L-shaped multi-cavity CFSTSSCs is not available. Therefore, the axial compression behavior of cross-shaped and L-shaped multi-cavity CFSTSSCs has been investigated, though experimental research and numerical simulation, in this study. First, axial compression tests were carried out on three cross-shaped and three L-shaped multi-cavity CFSTSSCs to analyze their failure modes, axial load-strain curve, ductility index, and ultimate bearing capacity. Then, fi nite element (FE) calculation models of cross-shaped and L-shaped multi-cavity CFSTSSCs were established. The FE models are in good agreement with the experimental results, which provides a foundation for further parameter analysis and failure mechanism study of special shaped columns. Finally, combining parameter analysis and limit equilibrium theory, equations for calculating the ultimate bearing capacity of cross-shaped and L-shaped multi-cavity CFSTSSCs were proposed. The results show that the error between the simplifi ed equation and the FE result is less than 15%, indicating that the equations can provide reference for practical engineering applications.

Exosomes derived from miR-214-3p overexpressing mesenchymal stem cells promote myocardial repair

Wenwu Zhu,Qingjie Wang,Jian Zhang,Ling Sun,Xiu Hong,Wei Du,Rui Duan,Jianguang Jiang,Yuan Ji,Haoran Wang,Bing Han 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00

Aims Exosomes are known as nanovesicles that are naturally secreted, playing an essential role in stem-mediated cardioprotection. This study mainly focused on investigating if exosomes derived from miR-214 overexpressing mesenchymal stem cells (MSCs) show more valid cardioprotective ability in a rat model of acute myocardial infarction (AMI) and its potential mechanisms. Methods Exosomes were isolated from control MSCs (Ctrl-Exo) and miR-214 overexpressing MSCs (miR-214OE-Exo) and then they were delivered to cardiomyocytes and endothelial cells in vitro under hypoxia and serum deprivation (H/SD) condition or in vivo in an acutely infarcted Sprague-Dawley rat heart. Regulated genes and signal pathways by miR-214OE-Exo treatment were explored using western blot analysis and luciferase assay. Results in vitro , miR-214OE-Exo enhanced migration, tube-like formation in endothelial cells. In addition, miR-214OE-Exo ameliorated the survival of cardiomyocytes under H/SD. In the rat AMI model, compared to Ctrl-Exo, miR-214OE-Exo reduced myocardial apoptosis, and therefore reduced infarct size and improved cardiac function. Besides, miR-214OE-Exo accelerated angiogenesis in peri-infarct region. Mechanistically, we identified that exosomal miR-214-3p promoted cardiac repair via targeting PTEN and activating p-AKT signal pathway. Conclusion Exosomes derived from miR-214 overexpressing MSCs have greatly strengthened the therapeutic efficacy for treatment of AMI by promoting cardiomyocyte survival and endothelial cell function.

Heat and Light-Induced Apple Skin Disorders

Larry E. Schrader,Jianshe Sun,Jianguang Zhang,David A. Felicetti,Jun Tian 한국원예학회 2006 한국원예학회 기타간행물 Vol.- No.-

New neo-lignan from Acanthopanax senticosus with protein tyrosine phosphatase 1B inhibitory activity

Jia Lin Li,Na Li,Shan-Shan Xing,Nan Zhang,BanBan Li,JianGuang Chen,안종석,Long Cui 대한약학회 2017 Archives of Pharmacal Research Vol.40 No.11

New neo-lignan, (7S, 8R)-3-hydroxyl-4-methoxyl-balanophonin (1), together with seven known compounds(2–8)were isolated fromthe EtOAc-soluble extract ofAcanthopanax senticosus. The structure of the newneo-lignanwas elucidated with spectroscopic and physico-chemicalanalyses. All the isolates were evaluated for in vitro inhibitoryactivity against PTP1B, VHR and PP1. Among them, the newcompound (1) was found to exhibit selective inhibitoryactivity on PTP1B with IC50 value 15.2 ± 1.4 lM.

ROS-activated CXCR2+ neutrophils recruited by CXCL1 delay denervated skeletal muscle atrophy and undergo P53-mediated apoptosis

Xiang Yaoxian,Dai Junxi,Li Yao,You Zongqi,Zhang Junpeng,Huang Xinying,Nie Shuqi,Chen Yujie,Xu Lei,Liu Fengming,Jiang Junjian,Xu Jianguang 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-

Neutrophils are the earliest master inflammatory regulator cells recruited to target tissues after direct infection or injury. Although inflammatory factors are present in muscle that has been indirectly disturbed by peripheral nerve injury, whether neutrophils are present and play a role in the associated inflammatory process remains unclear. Here, intravital imaging analysis using spinning-disk confocal intravital microscopy was employed to dynamically identify neutrophils in denervated muscle. Slice digital scanning and 3D-view reconstruction analyses demonstrated that neutrophils escape from vessels and migrate into denervated muscle tissue. Analyses using reactive oxygen species (ROS) inhibitors and flow cytometry demonstrated that enhanced ROS activate neutrophils after denervation. Transcriptome analysis revealed that the vast majority of neutrophils in denervated muscle were of the CXCR2 subtype and were recruited by CXCL1. Most of these cells gradually disappeared within 1 week via P53-mediated apoptosis. Experiments using specific blockers confirmed that neutrophils slow the process of denervated muscle atrophy. Collectively, these results indicate that activated neutrophils are recruited via chemotaxis to muscle tissue that has been indirectly damaged by denervation, where they function in delaying atrophy.