A numerical and theoretical investigation on composite pipe-in-pipe structure under impact

Xudong Qian,Yu Wang,J.Y. Richard Liew,Min-Hong Zhang 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.22 No.5

This paper investigates the transverse impact response for ultra lightweight cement composite (ULCC) filled pipe-in-pipe structures through a parametric study using both a validated finite element procedure and a validated theoretical model. The parametric study explores the effect of the impact loading conditions (including the impact velocity and the indenter shape), the geometric properties (including the pipe length and the dimensions of the three material layers) as well as the material properties (including the material properties of the steel pipes and the filler materials) on the impact response of the pipe-in-pipe composite structures. The global impact responses predicted by the FE procedure and by the theoretical model agree with each other closely. The parametric study using the theoretical approach indicates the close relationships among the global impact responses (including the maximum impact force and the maximum global displacement) in specimens with the equivalent thicknesses, proposed in the theoretical model, for the pipe-in-pipe composite structures. In the pipe-in-pipe composite structure, the inner steel pipe, together with the outer steel pipe, imposes a strong confinement on the infilled cement composite and enhances significantly the composite action, leading to improved impact resistance, small global and local deformations.

A Fibrin Matrix Promotes the Differentiation of EMSCs Isolated from Nasal Respiratory Mucosa to Myelinating Phenotypical Schwann-Like Cells

Chen, Qian,Zhang, Zhijian,Liu, Jinbo,He, Qinghua,Zhou, Yuepeng,Shao, Genbao,Sun, Xianglan,Cao, Xudong,Gong, Aihua,Jiang, Ping Korean Society for Molecular and Cellular Biology 2015 Molecules and cells Vol.38 No.3

Because Schwann cells perform the triple tasks of myelination, axon guidance and neurotrophin synthesis, they are candidates for cell transplantation that might cure some types of nervous-system degenerative diseases or injuries. However, Schwann cells are difficult to obtain. As another option, ectomesenchymal stem cells (EMSCs) can be easily harvested from the nasal respiratory mucosa. Whether fibrin, an important transplantation vehicle, can improve the differentiation of EMSCs into Schwann-like cells (SLCs) deserves further research. EMSCs were isolated from rat nasal respiratory mucosa and were purified using anti-CD133 magnetic cell sorting. The purified cells strongly expressed HNK-1, nestin, $p75^{NTR}$, S-100, and vimentin. Using nuclear staining, the MTT assay and Western blotting analysis of the expression of cell-cycle markers, the proliferation rate of EMSCs on a fibrin matrix was found to be significantly higher than that of cells grown on a plastic surface but insignificantly lower than that of cells grown on fibronectin. Additionally, the EMSCs grown on the fibrin matrix expressed myelination-related molecules, including myelin basic protein (MBP), 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) and galactocerebrosides (GalCer), more strongly than did those grown on fibronectin or a plastic surface. Furthermore, the EMSCs grown on the fibrin matrix synthesized more neurotrophins compared with those grown on fibronectin or a plastic surface. The expression level of integrin in EMSCs grown on fibrin was similar to that of cells grown on fibronectin but was higher than that of cells grown on a plastic surface. These results demonstrated that fibrin not only promoted EMSC proliferation but also the differentiation of EMSCs into the SLCs. Our findings suggested that fibrin has great promise as a cell transplantation vehicle for the treatment of some types of nervous system diseases or injuries.

A ZigBee-based Building Energy and Environment Monitoring System Integrated with Campus GIS

Kun Qian,Xudong Ma,Changhai Peng,Qing Ju,Mengyuan Xu 보안공학연구지원센터 2014 International Journal of Smart Home Vol.8 No.2

Characteristics of second harmonic generation with short pulse laser in nonlinear photonic crystals

Liejia Qian,Wanguo Zheng,Xudong Xu 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.43 No.42

Based on a calculation of the dispersion relation and a numerical simulation of the nonlinear wave equations, this paper theoretically analyzes the characteristics of second harmonic generation (SHG) with short pulse laser in one-dimensional photonic crystals (PCs). We propose and demonstrate a simple means for compensating for the group velocity mismatch (GVM), which is accomplished by using PCs in a tilted version. Unlike in the case of conventional bulk crystals, the strong group velocity dispersion (GVD) induced by the periodic structures in PCs plays a big role in nonlinear SHG processes. Similar to the eects of GVM, the eects of GVD in PCs broaden the harmonic pulse and/or decrease the conversion eciency. For the present structure used in PCs, we show that because of the in uences of GVD and the limited bandwidth of PCs, the shortest pulse appropriate for SHG will be around picosecond.

Determination of Structural Lightweight Concrete Mix Proportion for Floating Concrete Structures

김민욱,Xudong Qian,이명규,박우선,정신택,오남선 한국해안,해양공학회 2017 한국해안해양공학회 논문집 Vol.29 No.6

This study aims to provide information for the design and use of structural lightweight concrete (SLWC) for floating concrete structures in a marine environment. An experimental program was set up and comprehensive experimental campaign were carried out to determine SLWC mix proportions that can satisfy specified concrete strength, density, and slump values all of them were determined from previous research. Comparisons with previous SLWC mix designs that have been utilized for actual floating concrete structures were made. Key aspects needed to be considered regarding to the use of SLWC for floating marine concrete structures were discussed.

Relationship among porcine lncRNA TCONS_00010987, miR-323, and leptin receptor based on dual luciferase reporter gene assays and expression patterns

Ding, Yueyun,Qian, Li,Wang, Li,Wu, Chaodong,Li, DengTao,Zhang, Xiaodong,Yin, Zongjun,Wang, Yuanlang,Zhang, Wei,Wu, Xudong,Ding, Jian,Yang, Min,Zhang, Liang,Shang, Jinnan,Wang, Chonglong,Gao, Yafei Asian Australasian Association of Animal Productio 2020 Animal Bioscience Vol.33 No.2

Objective: Considering the physiological and clinical importance of leptin receptor (LEPR) in regulating obesity and the fact that porcine LEPR expression is not known to be controlled by lncRNAs and miRNAs, we aim to characterize this gene as a potential target of SSC-miR-323 and the lncRNA TCONS_00010987. Methods: Bioinformatics analyses revealed that lncRNA TCONS_00010987 and LEPR have SSC-miR-323-binding sites and that LEPR might be a target of lncRNA TCONS_00010987 based on cis prediction. Wild-type and mutant TCONS_00010987-target sequence fragments and wild-type and mutant LEPR 3'-UTR fragments were generated and cloned into pmiRRB-REPORT^TM-Control vectors to construct respective recombinant plasmids. HEK293T cells were co-transfected with the SSC-miR-323 mimics or a negative control with constructs harboring the corresponding binding sites and relative luciferase activities were determined. Tissue expression patterns of lncRNA TCONS_00010987, SSC-miR-323, and LEPR in Anqing six-end-white (AQ, the obese breed) and Large White (LW, the lean breed) pigs were detected by real-time quantitative polymerase chain reaction; backfat expression of LEPR protein was detected by western blotting. Results: Target gene fragments were successfully cloned, and the four recombinant vectors were constructed. Compared to the negative control, SSC-miR-323 mimics significantly inhibited luciferase activity from the wild-type TCONS_00010987-target sequence and wild-type LEPR-3'-UTR (p<0.01 for both) but not from the mutant TCONS_00010987-target sequence and mutant LEPR-3'-UTR (p>0.05 for both). Backfat expression levels of TCONS_00010987 and LEPR in AQ pigs were significantly higher than those in LW pigs (p<0.01), whereas levels of SSC-miR-323 in AQ pigs were significantly lower than those in LW pigs (p<0.05). LEPR protein levels in the backfat tissues of AQ pigs were markedly higher than those in LW pigs (p<0.01). Conclusion: LEPR is a potential target of SSC-miR-323, and TCONS_00010987 might act as a sponge for SSC-miR-323 to regulate LEPR expression.

Rapid S-N type life estimation for low cycle fatigue of high-strength steels at a low ambient temperature

Liuyang Feng,Xudong Qian 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.33 No.6

This paper presents a new efficient approach to estimate the S-N type fatigue life assessment curve for S550 high strength steels under low-cycle actions at –60°C. The proposed approach combines a single set of monotonic tension test and one set of fatigue tests to determine the key material damage parameters in the continuum damage mechanics framework. The experimental program in this study examines both the material response under low-cycle actions. The microstructural mechanisms revealed by the Scanning Electron Microscopy (SEM) at the low temperature, furthermore, characterizes the effect due to different strain ratios and low temperature on the low-cycle fatigue life of S550 steels. Anchored on the experimental results, this study validates the S-N curve determined from the proposed approach. The S-N type curve determined from one set of fatigue tests and one set of monotonic tension tests estimates the fatigue life of all specimens under different strain ratios satisfactorily.

A Fibrin Matrix Promotes the Differentiation of EMSCs Isolated from Nasal Respiratory Mucosa to Myelinating Phenotypical Schwann-Like Cells

Zhijian Zhang,Qian Chen,Jinbo Liu,Qinghua He,Yuepeng Zhou,Genbao Shao,Xianglan Sun,Xudong Cao,Aihua Gong,Ping Jiang 한국분자세포생물학회 2015 Molecules and cells Vol.38 No.3

Because Schwann cells perform the triple tasks of myelination, axon guidance and neurotrophin synthesis, they are candidates for cell transplantation that might cure some types of nervous-system degenerative diseases or injuries. However, Schwann cells are difficult to obtain. As another option, ectomesenchymal stem cells (EMSCs) can be easily harvested from the nasal respiratory mucosa. Whether fibrin, an important transplantation vehicle, can improve the differentiation of EMSCs into Schwann-like cells (SLCs) deserves further research. EMSCs were isolated from rat nasal respiratory mucosa and were purified using anti-CD133 magnetic cell sorting. The purified cells strongly expressed HNK-1, nestin, p75NTR, S-100, and vimentin. Using nuclear staining, the MTT assay and Western blotting analysis of the expression of cell-cycle markers, the proliferation rate of EMSCs on a fibrin matrix was found to be significantly higher than that of cells grown on a plastic surface but insignificantly lower than that of cells grown on fibronectin. Additionally, the EMSCs grown on the fibrin matrix expressed myelination-related molecules, including myelin basic protein (MBP), 2’,3’-cyclic nucleotide 3’-phosphodiesterase (CNPase) and galactocerebrosides (GalCer), more strongly than did those grown on fibronectin or a plastic surface. Furthermore, the EMSCs grown on the fibrin matrix synthesized more neurotrophins compared with those grown on fibronectin or a plastic surface. The expression level of integrin in EMSCs grown on fibrin was similar to that of cells grown on fibronectin but was higher than that of cells grown on a plastic surface. These results demonstrated that fibrin notonly promoted EMSC proliferation but also the differentiation of EMSCs into the SLCs. Our findings suggested that fibrin has great promise as a cell transplantation vehicle for the treatment of some types of nervous system diseases or injuries.

A complete integrity assessment of welded connections under high and low cycle fatigue followed by fracture failure

Liuyang Feng,Tianyao Liu,Xudong Qian,Cheng Chen 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.43 No.4

This paper presents a comprehensive integrity assessment of welded structural components, including uniform highand low-cycle fatigue assessment of welded plate joints and fatigue-induced fracture assessment of welded plate joints. This study reports a series of fatigue and fracture tests of welded plate joints under three-point bending. To unify the assessment protocol for high- and low-cycle fatigue of welded plate joints, this study develops a numerical damage assessment framework for both high- and low-cycle fatigue. The calibrated damage material parameters are validated through the smooth coupon specimens. The proposed damage-based fatigue assessment approach describes, with reasonable accuracy, the total fatigue life of welded plate joints under high- and low-cycle fatigue actions. Subsequently, the study performs a tearing assessment on the ductile crack extension of the fatigue-induced crack. The tearing assessment diagram derives from the load-deformation curve of a single-edge notched bend, SE(B) specimen and successfully predicts the load-crack extension relation for the reported welded plate joints during the stable tearing process.

Effects of weight on bit on torsional stick-slip vibration of oilwell drill string

Liping Tang,Xiaohua Zhu,Xudong Qian,Changshuai Shi 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.10

The stick-slip phenomenon is a type of dysfunction detrimental to the drilling operation. Field application shows that stick-slip phenomenon is inclined to appear when using a large Weight on bit (WOB). In this paper, effects of the WOB on the stick-slip vibration are investigated. Based on a lumped torsional pendulum model of the drilling system, equation of motion of the drill bit is obtained. By using parameters commonly used in field applications, the bit dynamics are analyzed and the stick-slip vibrations are discussed. During the stick-slip motions, the negative damping effect occurs in the transition from the stick phase to the slip phase. With the increasing WOB, the bit behavior may change from the stable motion to the stick-slip vibration once the WOB reaches the critical value. In case of stickslip vibration, the phase trajectory ultimately converges to a limit cycle which represents periodical bit motion. With increases in the WOB, the limit cycle enlarges. For cases without stick-slip vibrations, the drill bit vibrates damply and finally converges to a state of uniform motion. The results presented in this paper can be applied to interpret some of the field phenomena related to WOB.