Behavior of three-tube buckling-restrained brace with circumference pre-stress in core tube

Yang Li,Haiyan Qu,Shaowen Xiao,Peijun Wang,Yang You,Shuqing Hu 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.30 No.2

The behavior of a new Three-Tube Buckling-Restrained Brace (TTBRB) with circumference pre-stress (σθ,pre) in core tube are investigated through a verified finite element model. The TTBRB is composed of one core tube and two restraining tubes. The core tube is in the middle to provide the axial stiffness, to carry the axial load and to dissipate the earthquake energy. The two restraining tubes are at inside and outside of the core tube, respectively, to restrain the global and local buckling of the core tube. Based on the yield criteria of fringe fiber, a design method for restraining tubes is proposed. The applicability of the proposed design equations are verified by TTBRBs with different radius-thickness ratios, with different gap widths between core tube and restraining tubs, and with different levels of σθ,pre. The outer and inner tubes will restrain the deformation of the core tube in radius direction, which causes circumference stress (σθ) in the core tube. Together with the σθ,pre in the core tube that is applied through interference fit of the three tubes, the yield strength of the core tube in the axial direction is improved from 160 MPa to 235 MPa. Effects of gap width between the core tube and restraining tubes, and σθ,pre on hysteretic behavior of TTBRBs are presented. Analysis results showed that the gap width and the σθ,pre can significantly affect the hysteretic behavior of a TTBRB.

Effect of Carbon Nanotubes on the Transport and Retention of Bacteria in Saturated Porous Media

Yang, Haiyan,Tong, Meiping,Kim, Hyunjung American Chemical Society 2013 Environmental science & technology Vol.47 No.20

<P>This study investigated the influence of carbon nanotubes (CNTs) on the transport and retention behaviors of bacteria (<I>E. coli</I>) in packed porous media at both low and high ionic strength in NaCl and CaCl<SUB>2</SUB> solutions. At low ionic strengths (5 mM NaCl and 0.3 mM CaCl<SUB>2</SUB>), both breakthrough curves and retained profiles of bacteria with CNTs (both 5 and 10 mg L<SUP>–1</SUP>) were equivalent to those without CNTs, indicating the presence of CNTs did not affect the transport and retention of <I>E. coli</I> at low ionic strengths. The results were supported by those from cell characterization tests (i.e., viability, surface properties, sizes), which showed no significant difference between with and without CNTs. In contrast, breakthrough curves of bacteria with CNTs were lower than those without CNTs at high ionic strengths (25 mM NaCl and 1.2 mM CaCl<SUB>2</SUB>), suggesting that the presence of CNTs decreased cell transport at high ionic strengths. The enhanced bacterial deposition in the presence of CNTs was mainly observed at segments near the column inlet, leading to much steeper retained profiles relative to those without CNTs. Additional transport experiments conducted with sand columns predeposited with CNTs revealed that the codeposition of bacteria with CNTs, as well as the deposition of the cell–CNTs cluster formed in cell suspension due to cell bridging effect, largely contributed to the increased deposition of bacteria at high ionic strengths in porous media.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/esthag/2013/esthag.2013.47.issue-20/es4022415/production/images/medium/es-2013-022415_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/es4022415'>ACS Electronic Supporting Info</A></P>

Hypoxia-hindered methylation of PTGIS in endometrial stromal cells accelerates endometriosis progression by inducing CD16− NK-cell differentiation

Haiyan Peng,Lichun Weng,Shating Lei,Shuhui Hou,Shaoliang Yang,Mingqing Li,Dong Zhao 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-

Prostacyclin (PGI2) plays key roles in shaping the immune microenvironment and modulating vasodilation, whereas its contribution to endometriosis (EMs) remains largely unclear. Our study suggested that prostacyclin synthase (PTGIS)-dependent PGI2 signaling was significantly activated in EMs, which was involved in the hypoxic microenvironment of ectopic lesions and deficient methylation status of the PTGIS promoter. Notably, in vitro assays, hypoxia promoted PTGIS expression through DNA methyltransferase 1 (DNMT1)-mediated DNA methylation deficiency in endometrial stromal cells (ESCs); PTGIS overexpression enhanced the adhesive ability of ESCs and led to elevated PGI2 production, and PGI2 triggered CD16− (encoded by FCGR3, Fc fragment of IgG receptor IIIa) natural killer (NK)-cell differentiation through PGI2 receptor (IP, PTGIR) in an ESC/NK-cell coculture system. Our rodent model experiment suggested that treatment with the PGI2 analog iloprost and adoptive transfer of fcgr3 knockout (fcgr3−/−) NK cells aggravated EMs progression and that genetic ablation of ptgis (ptgis−/−) in ectopic lesions and treatment with the PTGIR antagonist RO1138452 partially rescued this outcome. Thus, our findings identified the contribution of PGI2 to EMs progression via enhancement of the adhesive ability of ESCs and inhibition of the activity of NK cells. We hypothesized that PGI2 is a target for EMs intervention and provide a rationale for studying pharmacological PTGIR inhibition and PTGIS genetic depletion therapies as therapeutic strategies for EMs.

Constraints on Biotic and Abiotic Role in the Formation of Fe-Si Oxides from the PACMANUS Hydrothermal Field

Yang Baoju,Zeng Zhigang,Qi Haiyan,Wang Xiaoyuan,Ma Yao,Rong Kunbo 한국해양과학기술원 2015 Ocean science journal Vol.50 No.4

Fe-Si oxide deposits were recovered from the PACMANUS (Papua New Guinea-Australia-Canada-Manus) hydrothermal field in Eastern Manus basin. Samples were loose and fragile. Optical and scanning electron microscopy showed that the samples had abundant rod-like or twisted filamentous and granular structures. Electron probe microanalysis revealed that these filaments and grains were mainly composed of Fe and Si. The presence of spherical grains on the surface of the filaments suggests the intergrowth of biotic and abiotic reactions. Biotic and abiotic kinetics competition always exists in the redox gradient. Based on the physico-chemical conditions of PACMANUS hydrothermal fluids, we calculated a strict abiotic oxidation rate of Fe2+ to Fe3+, which is approximately 0.0123 g/min. If the fluids had been erupting consistently and the concentration of Fe2+ was constant, 3.232 kg per year of Fe would be deposited in this vent. The amount of Fe oxides around the studied vent was larger than the amount determined by strict abiotic kinetic calculation. Bacteria may also play an important role in Fe oxidation. A mesh-like microenvironment constructed by biogenic filaments ensured adequate Fe2+ and low oxygen content for the growth of bacteria. Moreover, this structure promoted the deposition of abiotic Fe-Si oxides.

Mapping QTLs for Tissue Culture Response of Mature Wheat Embryos

Haiyan Jia,Dalong Yi,Jie Yu,Shulin Xue,Yang Xiang,Caiqin Zhang,Zhengzhi Zhang,Lixia Zhang,Zhengqiang Ma 한국분자세포생물학회 2007 Molecules and cells Vol.23 No.3

BPF-based Grid Voltage Feedforward Control of Grid-connected Converters for Improving Robust Stability

Yang, Shude,Tong, Xiangqian,Yin, Jun,Wang, Haiyan,Deng, Yaping,Liu, Le The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.2

Grid voltage feedforward is extensively used for controlling grid-connected converters. However, the conventional voltage feedforward control reduces the stability margins of the converter connected to a high-impedance grid. The effect mechanism of voltage feedforward on the grid-connected converter control under high-inductive conditions of the grid impedance is clearly explained in this study using the equivalent transformations of control block diagrams. Results show that the delay produced by the digital control is the root cause of this effect. An improved voltage feedforward strategy, in which a bandpass filter (BPF) is introduced into the feedforward path, is proposed to strengthen the converter's robust stability against grid impedance variations. The selection method of the BPF's bandwidth is also provided considering the tradeoff between the response speed to the grid voltage sag and the system's robust stability. The converter can work stably over a wide range of the grid impedance through the proposed approach. Simulation and experimental results fully verify the effectiveness of the BPF-based voltage feedforward strategy.

Diversity and Functions of Endophytic Fungi Associated with Roots and Leaves of Stipa purpurea in an Alpine Steppe at Qinghai-Tibet Plateau

( Xiaoyan Yang ),( Hui Jin ),( Lihong Xu ),( Haiyan Cui ),( Aiyi Xin ),( Haoyue Liu ),( Bo Qin ) 한국미생물 · 생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.7

Stipa purpurea is a unique and dominant herbaceous plant species in the alpine steppe and meadows on the Qinghai-Tibet Plateau (QTP). In this work, we analyzed the composition and diversity of the culturable endophytic fungi in S. purpurea according to morphological and molecular identification. Then, we investigated the bioactivities of these fungi against plant pathogenic fungi and 1- aminocyclopropane-1-carboxylate deaminase (ACCD) deaminase activities. A total of 323 fungal isolates were first isolated from S. purpurea, and 33 fungal taxa were identified by internal transcribed spacer primers and grouped into Ascomycota. The diversity of endophytic fungi in S. purpurea was significantly higher in roots as compared to leaves. In addition, more than 40% of the endophytic fungi carried the gene encoding for the ACCD gene. The antibiosis assay demonstrated that 29, 35, 28, 37 and 34 isolates (43.9, 53.1, 42.4, 56.1, and 51.5%) were antagonistic to five plant pathogenic fungi, respectively. Our study provided the first assessment of the diversity of culturedepending endophytic fungi of S. purpurea, demonstrated the potential application of ACCD activity and antifungal activities with potential benefits to the host plant, and contributed to high biomass production and adaptation of S. purpurea to an adverse environment.

BPF-based Grid Voltage Feedforward Control of Grid-connected Converters for Improving Robust Stability

Shude Yang,Xiangqian Tong,Jun Yin,Haiyan Wang,Yaping Deng,Le Liu 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.2

Grid voltage feedforward is extensively used for controlling grid-connected converters. However, the conventional voltage feedforward control reduces the stability margins of the converter connected to a high-impedance grid. The effect mechanism of voltage feedforward on the grid-connected converter control under high-inductive conditions of the grid impedance is clearly explained in this study using the equivalent transformations of control block diagrams. Results show that the delay produced by the digital control is the root cause of this effect. An improved voltage feedforward strategy, in which a bandpass filter (BPF) is introduced into the feedforward path, is proposed to strengthen the converter’s robust stability against grid impedance variations. The selection method of the BPF’s bandwidth is also provided considering the tradeoff between the response speed to the grid voltage sag and the system’s robust stability. The converter can work stably over a wide range of the grid impedance through the proposed approach. Simulation and experimental results fully verify the effectiveness of the BPF-based voltage feedforward strategy.

Nematicidal activity against Aphelenchoides besseyi and Ditylenchus destructor of three biflavonoids, isolated from roots of Stellera chamaejasme

Hui Jin,Haiyan Cui,Xiaoyan Yang,Lihong Xu,Xudong Li,Rentao Liu,Zhiqiang Yan,Xiuzhuang Li,Weili Zheng,Yuhui Zhao,Xiaoxia Song,Lihua Zhong,Anxiang Su,Bo Qin 한국응용곤충학회 2018 Journal of Asia-Pacific Entomology Vol.21 No.4

Aphelenchoides besseyi and Ditylenchus destructor can cause serious problems for a number of important agricultural crops and vegetables. In this study, the ethanol extract of Stellera chamaejasme L. roots showed strong nematicidal activity against Aphelenchoides besseyi and Ditylenchus destructor. By using a bioactivity-driven fractionation, three biflavonoids were isolated from the extract and their structures were identified by mass and nuclear magnetic resonance spectral data. Nematicidal activity bioassays revealed that isoneochamaejasmin A had the strongest nematicidal activity against A. besseyi and D. destructor with LC 50 values of 2.32 and 0.18 mM at 72 h, respectively. Chamaejasmenin B displayed weaker nematicidal activity against A. besseyi with an LC 50 value of 3.94 mM at 72 h. Neochamaejasmin B induced the lowest mortality against D. destructor with an LC 50 values of 15.6 mM at 72 h. These results suggested that the kind and position of substitutions and the relative configuration of 2-H/3-H and 2”-H/3”-H could be considered as important factors responsible for the nematicidal activity of these purified C-3/C-3″ biflavonoids.

Dynamics of high-speed train in crosswinds based on an air-train-track interaction model

Zhai, Wanming,Yang, Jizhong,Li, Zhen,Han, Haiyan Techno-Press 2015 Wind and Structures, An International Journal (WAS Vol.20 No.2

A numerical model for analyzing air-train-track interaction is proposed to investigate the dynamic behavior of a high-speed train running on a track in crosswinds. The model is composed of a train-track interaction model and a train-air interaction model. The train-track interaction model is built on the basis of the vehicle-track coupled dynamics theory. The train-air interaction model is developed based on the train aerodynamics, in which the Arbitrary Lagrangian-Eulerian (ALE) method is employed to deal with the dynamic boundary between the train and the air. Based on the air-train-track model, characteristics of flow structure around a high-speed train are described and the dynamic behavior of the high-speed train running on track in crosswinds is investigated. Results show that the dynamic indices of the head car are larger than those of other cars in crosswinds. From the viewpoint of dynamic safety evaluation, the running safety of the train in crosswinds is basically controlled by the head car. Compared with the generally used assessment indices of running safety such as the derailment coefficient and the wheel-load reduction ratio, the overturning coefficient will overestimate the running safety of a train on a track under crosswind condition. It is suggested to use the wheel-load reduction ratio and the lateral wheel-rail force as the dominant safety assessment indices when high-speed trains run in crosswinds.