13 results on '"Xu, Chengxiang"'
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2. Will paper microzones become the greenest chemistry method for electrolytic analysis?
- Author
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Liu, Xian, Wang, Qirui, Peng, Ke, Wu, Xi, Wang, Xun, Zhu, Lei, and Xu, Chengxiang
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- 2022
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3. Heavy metal enrichment and health risk assessment of karst cave fish in Libo, Guizhou, China
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Xu, Chengxiang, Yan, Hanlin, and Zhang, Siqiang
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- 2021
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4. Experimental research and finite element analysis on seismic behavior of CFRP-strengthened seismic-damaged composite steel-concrete frame columns.
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Peng, Sheng, Xu, Chengxiang, Lu, Mengxiao, and Yang, Jianming
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CARBON fiber-reinforced plastics , *FINITE element method , *SEISMIC response , *STEEL framing fractures , *CYCLIC loads - Abstract
Four composite steel–concrete frame columns were constructed to investigate the seismic performance of seismic-damaged composite steel–concrete frame columns strengthened with carbon fiber reinforced polymer. The test consisted of pre-damage loading, rehabilitation with carbon fiber reinforced polymer and destruction tests under lateral cyclic loading. The effectiveness of strengthening seismic-damaged columns with carbon fiber reinforced polymer and the strengthening effect on different degrees of seismic damage were studied. Also, based on the test data, various parameters were obtained, including the hysteretic loops, skeleton curves, axial compression ratio, number of pasted layers of carbon fiber reinforced polymer, ductility, dissipative ability, ultimate strength, stiffness degradation, etc. The results revealed that the failure mode of all the columns was bending failure. The study indicates that the rehabilitated columns can reach or even exceed the level of their original seismic performance before seismic damage up to a certain extent of damage level. Composite steel–concrete frame columns strengthened with carbon fiber reinforced polymer sheets were simulated using the finite element analysis software ABAQUS. The comparison of the results of the conducted analytical study with the experimental results revealed that they are basically consistent with each other. [ABSTRACT FROM AUTHOR]
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- 2018
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5. Physical modeling of lateral spreading induced by inclined sandy foundation in the state of zero effective stress.
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Chen, Yumin, Xu, Chengxiang, Liu, Hanlong, and Zhang, Wengang
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STRAINS & stresses (Mechanics) , *SAND , *SATURATION (Chemistry) , *SOIL liquefaction , *DYNAMIC loads , *SALINE waters - Abstract
The state of zero effective stress is a situation at which the effective stress of saturated sand decreases to zero in the process of liquefaction. In the state of zero effective stress, sand particles suspend in water and the foundation is vulnerable to much large lateral deformation. The state of zero effective stress can be achieved through dynamic loading tests, but the obtained state is difficult to sustain a steady situation. To simulate the suspended sand in water under fully liquefied condition, plastic sand, characterized by small specific gravity, is used instead of quartz sand to build an inclined foundation. Salt water with similar density is used to pass in slowly near bottom of the foundation. As observed in tests, the plastic sand is able to suspend in sodium chloride solution (salt water) of a specific density and thus this model can be used to simulate the lateral spreading of a foundation under zero effective stress state. Lateral deformation occurs within a certain depth beneath the ground and the magnitude increases from the bottom up, showing nonlinear behaviors. This paper presents a physical modeling approach for achieving the state of zero effective stress under static laboratory condition. [ABSTRACT FROM AUTHOR]
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- 2015
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6. Technique of grafting with Wufanshu (Vaccinium bracteatum Thunb.) and the effects on blueberry plant growth and development, fruit yield and quality.
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Xu, Chengxiang, Ma, Yangping, and Chen, Hua
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GRAFTING (Horticulture) , *VACCINIUM , *BLUEBERRIES , *PLANT growth , *PLANT development , *FRUIT yield , *FRUIT quality - Abstract
Propagation and cultivation results showed that grafting southern highbush blueberry cultivar ʽSharpblueʼ taking Wufanshu ( Vaccinium bracteatum Thunb.) as rootstock has much high survival rate, and inlaid bud-grafting and one-bud cut-grafting were both suitable for application. The grafted blueberry saplings integrated the excellent biological traits of rootstock species and scion cultivar, growth vigor was markedly stronger than that of the same-aged none-grafted blueberry in field planting. Further more, early bearing and productivity and fruit quality of grafted blueberry were also significantly improved. Grafting is a practical and efficient technology innovation in blueberry production. [ABSTRACT FROM AUTHOR]
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- 2014
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7. Evaluation of photodegradation performance by paper microzones.
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Liu, Xian, Xu, Chengxiang, Xie, Shiwei, Zhu, Lei, and Wang, Xun
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- 2022
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8. One-step facile synthesis of shell-pearl structured photocatalysts for efficient removal of selected PPCPs from wastewater.
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Liu, Xian, Xu, Chengxiang, Zhu, Lei, Xie, Shiwei, Shen, Shihao, and Wang, Xun
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TITANIUM dioxide ,SALICYLIC acid ,STRUCTURE-activity relationships ,PHOTOCATALYSTS ,BISMUTH titanate - Abstract
There is an enlightening phenomenon in nature where mussels can purify water following swallowing microorganisms, debris, gravel, etc. Inspired by this phenomenon, we simulated the shell-pearl structure of a clam, and developed a unique method to synthesize Bi 2 O 3 intercalated bismuth titanate and molecularly imprinted TiO 2 microbead composites. Salicylic acid (SA) as an organic molecule (also target pollutant) plays a key role in the protection and formation of Bi 2 O 3 , which is key to obtaining the structure of mussel shell. The open shell-pearl bionic structure enables efficient transport of excited electrons across a variety of surface interfaces, while suppressing the complexity of photogenerated carrier that drives photocatalytic efficiency. Results show that the synthesized shell-pearl type catalyst achieved 92.54% degradation efficiency of salicylic acid under 30 min UV irradiation, which is 1.97 times higher than that of TiO 2. The high degradation efficiency indicate that pearl type catalyst has promising applications in future environmental purification as well as human health. [Display omitted] • Successful synthesis of open shell-pearl structure photocatalyst. • The synthesized catalyst achieved 92.54% degradation efficiency of salicylic acid. • Imprinted molecules proved to have a protective effect. • The new structure-activity relationship has been fully demonstrated. [ABSTRACT FROM AUTHOR]
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- 2021
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9. Influence of the degree of damage and confinement materials on the seismic behavior of RC beam-SRC column composite joints.
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Xu, Chengxiang, Peng, Sheng, Wang, Chenfei, and Ma, Zuotao
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EARTHQUAKE resistant design , *COMPOSITE columns , *CARBON fiber-reinforced plastics , *SEISMIC response , *FINITE element method , *CYCLIC loads , *ENERGY dissipation - Abstract
• Influence of damage degrees and confinement materials on seismic behavior of joints. • FE models of strengthened joints are calibrated with test results. • The predicted models of the shear capacity are good agreement with test results. • The results provide useful information for the engineering application. The seismic behavior of reinforced concrete (RC) beam-steel-reinforced concrete (SRC) column composite joints strengthened with carbon fiber-reinforced polymer (CFRP) sheets and enveloped steel jackets (ESJ) was investigated. Based on the existing regulations, nine specimens were designed and built to simulate pre-damage loading, rehabilitation with CFRP sheets or ESJ, and destruction tests under lateral cyclic loading to determine the performance of the two reinforcement materials (CFRP sheets and ESJ) for different degrees of seismic damage. An analysis of the hysteretic curves, skeleton curves, ductility, energy dissipation, bearing capacity degradation, stiffness degradation, and strain-displacement curves of the specimens indicated that the two strengthening materials exhibited good reinforcement performance. The ESJ improved the bearing capacity and stiffness of the specimens and the CFRP sheets improved the ductility and energy dissipation of the specimens, thereby improving the seismic behavior of the specimens. The severely damaged specimen strengthened with the CFRP sheets or ESJ did not collapse in a simulated strong earthquake and was similar to or even exceeded the seismic performance of the original specimen; this result is important and applicable to engineering practice. The ductility and energy dissipation was lower for the ESJ-strengthened specimen than the CFRP-strengthened specimen. Therefore, the ESJ material is preferable when only one type of material is used for strengthening the specimen. The seismic performance of the RC beam-SRC column frame joints strengthened with the CFRP sheets and ESJ was simulated using the finite element analysis software ABAQUS. There was a good agreement between the simulation results and the experimental results. It was proved that the simulated and experimental results of the ultimate bearing capacity of the joints in the core zones were in good agreement, which meets the design principle of "strong joint, weak member". [ABSTRACT FROM AUTHOR]
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- 2020
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10. Experimental investigation on bond-slip performance and damage evolution mechanism of deformed reinforcing bar embedded in steel polyvinyl-alcohol hybrid fiber high performance concrete after high temperature.
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Xu, Qiqi, Jiang, Xuepeng, Lv, Hongjie, and Xu, Chengxiang
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HIGH strength concrete , *REINFORCING bars , *HIGH temperatures , *STRESS-strain curves , *FIBERS , *STEEL bars - Abstract
Hybrid Fiber High Performance Concrete (HFHPC) utilizes the synergistic effects of macro and micro fibers at different stages, which can effectively improve its mechanical properties, fracture toughness, ductility, and impact resistance after high temperature. The bonding between steel bars and hybrid concrete is a fundamental prerequisite for ensuring that these two materials with completely different mechanical properties work together. In order to study on bond-slip performance and damage evolution mechanism of deformed reinforcing bar embedded in steel-polyvinyl-alcohol (S-PVA) hybrid fiber high performance concrete (HFHPC) after high temperature, a total of 75 specimens were designed and manufactured by selecting volume fraction of steel fiber and PVA fiber and dosing of slag powder as the orthogonal test factors, and the central pull-out test were completed after exposure to room temperature, 200℃, 400℃, 600℃, and 800℃. The experimental results indicate that the bonding failure mode of HFHPC specimens all showed steel bar pull-out failure after high temperature, and the bond stress-slip curve can be divided into 4 stages: elastic rise stage, nonlinear rise stage, plastic degradation stage, and residual stage. As the temperature increases, the bonding strength of HFHPC specimens gradually decreases and the peak slip gradually increases. The addition of hybrid fibers can significantly improve the bonding ductility and energy dissipation capacity of deformed reinforcing bar embedded in S-PVA HFHPC after high temperature. When the temperature is below 200℃, the bonding strength damage rate of S-PVA HFHPC specimens is relatively slow; when the temperature exceeds 200℃, the bonding strength damage rate of S-PVA HFHPC specimens increases. • The effects of steel-polyvinyl-alcohol hybrid fibers on bond-slip performance after high temperature were investigated. • Improvements in the bonding failure mode, bond strength, slip, energy consumption and ductility after high temperature were observed. • Damage evolution mechanism of deformed reinforcing bar embedded in steel polyvinyl-alcohol hybrid fiber high performance concrete after -high temperature were developed. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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11. Compression behavior of GFRP reinforced hybrid fibre reinforced concrete short columns subjected to eccentric loading.
- Author
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Xiao, Liangli, Hu, Hongjing, Peng, Shuang, Du, Zhuang, and Xu, Chengxiang
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ECCENTRIC loads , *CONCRETE columns , *REINFORCED concrete , *FIBERS , *COOPERATIVE binding (Biochemistry) , *FIBER-reinforced concrete - Abstract
• The mechanical property tests and test of GFRP reinforced hybrid fibre concrete short columns subjected to eccentric compression were conducted. • The cooperative effect of the GFRP reinforcement and the steel-PVA hybrid fibre concrete with different fibre ratios under eccentric loading was explored. • The addition of fibres can effectively prevent the crack generation and development and improve the bonding property between reinforcement bars and concrete. • The equation for the calculation of the ultimate compressive capacity of partial sections of eccentric columns is proposed. This paper presents the results of an experimental study carried out on the GFRP reinforced hybrid fibre concrete short columns subjected to eccentric compression. In this study, hybrid fiber-reinforced concrete was prepared in different volume ratios of hybrid fibers and the cooperative effect of the GFRP reinforcement and the steel-PVA hybrid fibre concrete with different fibre ratios under eccentric loading was explored. 10 GFRP reinforced hybrid fibre concrete short columns and 2 plain reinforced concrete short columns were tested to investigated their eccentric compressive properties. The tests results are presented in terms of failure modes, longitudinal reinforcement strain, concrete compressive strain and compressive load capacity of GFRP reinforced hybrid fibre concrete eccentrically compressed short columns. The results show that the concrete on the compressed side was crushed when the specimen under both the initial eccentricity of 50 mm and 100 mm the reinforcement were pulled on the tension side of specimen under a larger initial eccentricity of 100 mm. The addition of fibres can effectively prevent the crack generation and development and improve the bonding property between reinforcement and concrete. Besides, the addition of steel fibre contributes a better performance on the ultimate compressive capacity of specimen under a lager initial eccentricity with an optimal ratio of steel fibre at 1.4 %. PVA fibre effectively improve the ductility of the concrete, so that the hybrid fibre concrete elements remain relatively its integrity after failure. Finally, considering the effect of GFRP reinforcement and different ratios of steel fibre and PVA fibre on the compressive capacity of short concrete columns, the equation for the calculation of the ultimate compressive capacity of partial sections of eccentric columns is proposed, and a good agreement was observed between the tested and calculated value. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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12. Seismic performance of L-shaped short-leg shear walls with different concealed support materials.
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Xiao, Liangli, Shi, Yakun, Li, Yao, and Xu, Chengxiang
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SHEAR walls , *CYCLIC loads , *REINFORCING bars , *STEEL bars , *ENERGY dissipation , *STEEL framing - Abstract
This paper reports a study of the effects of different concealed bracing materials on the seismic performance of short-legged shear walls and presents the results of low-frequency cyclic loading tests on three L-shaped short-leg shear walls—one wall without concealed bracing and the other two with concealed bracing materials of steel bars and SMA bars, respectively. The tests were aimed mainly at analyzing the effects of different concealed bracing materials on seismic performance indicators such as crack pattern, bearing capacity, ductility, hysteresis performance, stiffness, and energy dissipation of the L-shaped short-leg shear walls. The results revealed that their seismic performance with concealed bracing was better than without concealed bracing. The short-leg shear walls with SMA bar concealed bracing had the lowest number of cracks and the smallest crack width, and the effect of delaying the development of cracks was more evident. The short-leg shear walls with steel reinforcement and SMA-bar concealed bracing were better in bearing capacity, ductility, and energy dissipation capacity, with, respectively, 11% and 26.3% increase in ultimate load, 4% and 18.6% increase in ultimate displacement, and 12% and 28% increase in energy dissipation. It can be seen that setting concealed bracing effectively enhances the seismic performance of short-leg shear walls, and that short-leg shear walls with concealed SMA bar bracing have the most significant improvement in seismic performance. • The low-frequency cyclic loading tests on three L-shaped short-leg shear walls with different concealed bracing materials were conducted. • The effects of different concealed bracing materials on seismic performance indicators of the L-shaped short-leg shear walls were explored. • The short-leg shear walls with concealed SMA bar bracing have the most significant improvement in seismic performance. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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13. Biomagnification and trophic transfer of total mercury and methylmercury in a sub-tropical montane forest food web, southwest China.
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Li, Chan, Xu, Zhidong, Luo, Kang, Chen, Zhuo, Xu, Xiaohang, Xu, Chengxiang, and Qiu, Guangle
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MOUNTAIN forests , *BIOMAGNIFICATION , *CARBON in soils , *MERCURY , *TOP predators , *METHYLMERCURY , *FOOD chains - Abstract
Little is known about the bioaccumulation and trophic transfer of total mercury (THg) and methylmercury (MeHg) via food webs in terrestrial ecosystems, especially in subtropical forest ecosystems. In the present study, THg and MeHg were determined as well as the carbon (δ13C) and nitrogen (δ15N) isotope composition in samples of soils, plants, invertebrates, and songbird feathers to construct food webs in a remote subtropical montane forest in Mt. Ailao, southwest China and assess the bioaccumulation, biomagnification, and trophic transfer of Hg. Results showed that the trophic levels (TLs) of all consumers ranged from 0.8 to 3.3 and followed the order of songbirds > spiders > omnivorous insects > herbivorous insects > plants, and THg and MeHg exhibited a clear biomagnification up the food chain from plants-herbivorous/omnivorous insects-spiders-songbirds. The lowest MeHg concentration was observed in pine needles ranged from 0.104 to 0.949 ng g−1 with only a 1.6% ratio of MeHg to THg (MeHg%), while the highest MeHg concentrations ranged from 425 to 5272 ng g−1 in songbirds with MeHg% values of up to 96%. High values of trophic magnification slope (TMS) for THg (0.22) and MeHg (0.38) were observed in plant-invertebrate-songbird food chain, verifying the significant bioaccumulation of Hg, particularly MeHg, in the remote subtropical forest ecosystem. This study confirmed the production and efficient biomagnification of MeHg in remote subtropical montane forest and the significant bioaccumulation of MeHg in terrestrial top predators. [Display omitted] • THg and MeHg increased with trophic positions in forest food webs. • THg exceeded adverse effect thresholds in insectivorous songbirds. • MeHg significantly biomagnified in subtropical forest food webs. Significant biomagnification of methylmercury exists in a remote subtropical forest food web. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
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