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Nonlinear Analysis on the Static and Cyclic Behaviors of UHPC Filled Rectangular Steel Tube Columns
Heng Cai,Fangqian Deng,Yanxiang Yan 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.3
In this paper, a fiber-based computational model is developed for the nonlinear analysis on the static and cyclic behaviors of ultra-high performance concrete filled rectangular steel tube (UHPCFST) columns. In the computational framework, a simplified compressive constitutive model of UHPC confined by rectangular steel tubes is firstly proposed based on available experimental data. Then, two approaches are adopted for considering the local buckling of steel tubes. The second-order as well as the material nonlinearity are also taken into account. Finally, comparative analyses between the predicted and experimental results of the UHPCFST columns are undertaken to verify the robustness and reliability of the fiber-based model. It is shown that the developed fiber-based modeling technique can predict the structural performance of UHPCFST columns with good satisfaction.
Heng Cai,Fangqian Deng 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.85 No.5
In order to deeply reveal the working mechanism of ultra-high performance concrete (UHPC) filled steel tubular columns (UHPCFSTs) under cyclic loading, a three-dimension (3D) macro-mesoscale finite element (FE) model was established considering the randomness of steel fibers and the damage of UHPC. Model correctness and reliability were verified based on the experimental results. Next, the whole failure process of UHPC reinforced with steel fibers, passive confinement effect and internal force distribution laws were comprehensively analyzed and discussed. Finally, a simplified and practical method was proposed for predicting the ultimate bending strengths of UHPCFSTs. It was found that the non-uniform confinement effect of steel tube occurred when the drift ratio exceeded 0.5%, while the confining stress increased then decreased afterwards. There was preferable synergy between the steel tube and UHPC until failure. Compared with experimental results, the ultimate bending strengths of UHPCFSTs were undervalued by the current code provisions such as AISC360-10, EC4 and GB50936 with computed mean values (MVs) of 0.855, 0.880 and 0.836, respectively. The proposed practical method was highly accurate, as evidenced by a mean value of 1.058.
Wang, Cai Yi,Kim, Donghwa,Zhu, Yan Kui,Oh, Dong-Chan,Huang, Ri Zhen,Wang, Heng-Shan,Liang, Dong,Lee, Sang Kook American Society of Pharmacognosy 2019 Journal of natural products Vol.82 No.11
<P>Three new germacrane sesquiterpenoid-type alkaloids with an unusual Δ<SUP>8</SUP>-7,12-lactam moiety, glechomanamides A-C (<B>1</B>-<B>3</B>), and two pairs of 7,12-hemiketal sesquiterpenoid epimers (<B>4a</B>/<B>b</B>, <B>5a</B>/<B>b</B>) were isolated from <I>Salvia scapiformis</I>. Their structures were elucidated by spectroscopic methods including HRESIMS, IR, UV, and 1D and 2D NMR and also confirmed by single-crystal X-ray diffraction analysis. The chemical transformation of compounds <B>1</B>-<B>5</B> in a solution environment was analyzed by 2D NMR spectroscopy. The aza acetallactams (<B>1</B>-<B>3</B>) were stable in organic solvent, while single crystals of the hemiacetal esters (<B>4a</B>/<B>b</B>, <B>5a</B>/<B>b</B>) underwent a tautomeric equilibrium after being dissolved. Single crystals of <B>4a</B>, <B>4b</B>, and <B>5a</B> were obtained for the first time as their naturally occurring forms. Glechomanamide B (<B>2</B>) exhibited antiangiogenic activity by suppression of vascular endothelial growth factor (VEGF)-induced tube formation through modulation of VEGF receptor 2 (VEGFR2)-mediated signaling pathways in human umbilical vascular endothelial cells (HUVECs). In addition, compound <B>2</B> also showed the significant suppression of mRNA expression associated with glycolysis and angiogenesis biomarkers in high glucose (30 mM)-induced HUVECs. These findings suggest that compound <B>2</B> might be a potential lead compound candidate for the management of diabetic retinopathy.</P> [FIG OMISSION]</BR>
Knockdown of Bcl-3 Inhibits Cell Growth and Induces DNA Damage in HTLV-1-infected Cells)
Gao, Cai,Wang, Xia,Chen, Lin,Wang, Jin-Heng,Gao, Zhi-Tao,Wang, Hui Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.1
Oncoprotein Bcl-3 is perceived as an unusual member of $I{\kappa}B$ family since it can both stimulate and suppress NF-${\kappa}B$ activation. Aberrant Bcl-3 results in increased cell proliferation and survival, suggesting a contribution to malignant potential and elevated levels of Bcl-3 have been observed in many HTLV-1-infected T cell lines and ATL cells. To investigate the specific roles of Bcl-3 in HTLV-1-infected cells, we knocked down Bcl-3 expression using shRNA and then examined the consequences with regard to DNA damage and cell proliferation, as well as NF-${\kappa}B$ activation. The HTLV-1 encoded protein Tax promotes Bcl-3 expression and nuclear translocation. In HTLV-1-infected cells, Bcl-3 knockdown obviously induced DNA damage. Cell growth and NF-${\kappa}B$ activation were reduced in HTLV-1-infected or Tax positive cells when Bcl-3 expression was decreased. Together, our results revealed positive roles of Bcl-3 in DNA stabilization, growth and NF-${\kappa}B$ activation in HTLV-1-infected cells.
Wang, Cai-Xia,Wang, Xiang,Liu, Hai-Bai,Zhou, Zhi-Heng Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.1
Objective: Altered regulation of many transcription factors has been shown to play important roles in the development of leukemia. hMSH2 can modulate the activity of some important transcription factors and is known to be a regulator of hematopoietic differentiation. Herein, we investigated epigenetic regulation of hMSH2 and its influence on cell growth and overall survival of acute lymphoblastic leukemia (ALL) patients. Methods: hMSH2 promoter methylation status was assessed by COBRA and pyrosequencing in 60 ALL patients and 30 healthy volunteers. mRNA and protein expression levels of hMSH2, PCNA, CyclinD1, Bcl-2 and Bax were determined by real time PCR and Western blotting, respectively. The influence of hMSH2 on cell proliferation and survival was assessed in transient and stable expression systems. Results: mRNA and protein expression of hMSH2 and Bcl-2 was decreased, and that of PCNA, CyclinD1 and Bax was increased in ALL patients as compared to healthy volunteers (P<0.05). hMSH2 was inactivated in ALL patients through promoter hypermethylation. Furthermore, hMSH2 hypermethylation was found in relapsed ALL patients (85.7% of all cases). The median survival of patients with hMSH2 methylation was shorter than that of patients without hMSH2 methylation (log-rank test, P=0.0035). Over-expression of hMSH2 in cell lines resulted in a significant reduction in growth and induction of apoptosis. Conclusions: This study suggests that aberrant DNA methylation and epigenetic inactivation of hMSH2 play an important role in the development of ALL through altering cell growth and survival.
Pseudo-Static Test Research on Behavior of UHPC-Filled Rectangular Steel Tubular Columns
Yanxiang Yan,Heng Cai,Tao Cheng 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.7
This paper examines the cyclic behaviour of 13 ultra-high performance concrete filled steel tube columns (UHPCFSTs) by using pseudo-static test. The parameters such as the axial compression ratio, the steel tube thickness, the aspect ratio (h/b) and the loading modes (loaded with 10 cycles, 3 cycles and monotonic loading) are taken into account, and the effects of the parameters are discussed. The results have shown that there are three types of failure modes for UHPCFSTs named the flexural failure mode, the compression-flexure failure mode and the welding seam fracture. The damage to the bottom of the columns is more serious compared to other positions. UHPCFSTs exhibit favorable seismic performance, which reflects that the equivalent viscous damping coefficients for UHPCFSTs failure are no less than 0.3, and the drift ratios of elasticity and elastoplasticity are within the scopes of 1.21% − 2.18% and 2.36% − 4.58%, respectively. The cumulative damage is not serious for specimens loaded with 10 cycles and 3 cycles under the drift ratio of 2%, whilst under the drift ratio of 4%, the specimens loaded with 10 cycles experience more serious damage compared with that loaded with 3 cycles.
Dynamic behavior analysis of push-the-bit rotary steerable bottom hole assembly
Zhi-chuan Guan,Heng Wang,Yu-cai Shi,Wei-qing Chen,Guo-shan Zhao,Jian-yun Wang,Guang-qiang Cao 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.4
Rotary steerable drilling technology is currently an advanced technology in the field of drilling engineering. A good understanding of dynamic behavior of rotary steerable system will benefit the drilling progress. Aimed at push-the-bit type of rotary steerable tool, finite element method was employed to model the rotary steerable bottom hole assembly (RSBHA) and establish the motion equation. Contact interaction between drill string and wellbore wall was analyzed and taken as the constraint condition in solving RSBHA motion equation. Force applied by steering pads was as the external force acting at the pads node. Then RSBHA motion state and bit lateral force were obtained by using Newmark method to solve the motion equation. A case was given and effects of influencing factors were analyzed. The results show that stick-slip phenomenon occurs under 60 r/min rotary speed condition and disappears when rotary speed rises to 90 r/min. Fully developed backward whirl comes into being at the near-bit stabilizer when rotary speed increases to 120 r/min. High weight on bit intensifies bit torsional vibration while larger pads’ steering force decreases the bit torsional vibration. Upper stabilizer plays a part in weakening RSBHA backward whirl under high rotary speed condition but reduces the inclination force. Time average of bit lateral force is mainly determined by pads’ steering force. Based on the results, corresponding suggestions were proposed to make the RSBHA be better used in the field applications.
Ju-Hua Wang,Xiu-Heng Xue,Jie Zhou,Cai-Yun Fan,Qian-Qian Xie,Pan Wang 대한기생충학열대의학회 2015 The Korean Journal of Parasitology Vol.53 No.3
Cryptosporidium andersoni ATP-binding cassette (CaABC) is an important membrane protein involved in substrate transport across the membrane. In this research, the nucleotide binding domain (NBD) of CaABC gene was amplified by PCR, and the eukaryotic expression vector of pEGFP-C1-CaNBD was reconstructed. Then, the recombinant plasmid of pEGFP-C1-CaNBD was transformed into the mouse intestinal epithelial cells (IECs) to study the iron transportation function of CaABC. The results indicated that NBD region of CaABC gene can significantly elevate the transport efficiency of Ca<SUP>2+</SUP>, Mg<SUP>2+</SUP>, K<SUP>+</SUP>, and HCO₃<SUP>-</SUP> in IECs (P<0.05). The significance of this study is to find the ATPase inhibitors for NBD region of CaABC gene and to inhibit ATP binding and nutrient transport of CaABC transporter. Thus, C. andersoni will be killed by inhibition of nutrient uptake. This will open up a new way for treatment of cryptosporidiosis.