Experimental and analytical performance evaluation of steel beam to concrete-encased composite column with unsymmetrical steel section joints

Yunfeng Xiao,Lei Zeng,Zhenkun Cui,Siqian Jin,Yiguang Chen 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.23 No.1

The seismic performance of steel beam to concrete-encased composite column with unsymmetrical steel section joints is investigated and reported within this paper. Experimental and analytical evaluation were conducted on a total of 8 specimens with T-shaped and L-shaped steel section under lateral cyclic loading and axial compression. The test parameters included concrete strength, stirrup ratio and axial compression ratio. The response of the specimens was presented in terms of their hysterisis loop behavior, stress distribution, joint shear strength, and performance degradation. The experiment indicated good structural behavior and good seismic performance. In addition, a three-dimensional nonlinear finite-element analysis simulating was conducted to simulate their seismic behaviors. The finite-element analysis incorporated both bond-slip relationship and crack interface interaction between steel and concrete. The results were also compared with the test data, and the analytical prediction of joint shear strength was satisfactory for both joints with T-shaped and L-shaped steel section columns. The steel beam to concrete-encased composite column with unsymmetrical steel section joints can develop stable hysteretic response and large energy absorption capacity by providing enough stirrups and decreased spacing of transverse ties in column.

Microstructure design and energy transfer in Gd2(WO4)3: Yb3+/Er3+ phosphors

Wang Yunfeng,Chen Jun,Wei Xiaoyu,Cui Shaobo,Jia Xiao 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.78 No.9

Rare-earth-doped upconverison luminescent (UCL) materials have wide application prospects in the feld of nanoptoelectronics technology. However, achieving highly efficient UCL materials is still a big challenge due to the serious nonradiative energy loss in the host materials. In this research, Gd2(WO4)3: Yb3+, Er3+ inverse opal photonic crystals (IOPCs) were prepared using a polymethylmethacrylate (PMMA) template-assisted method, and the efects of modulations of the IOPC structure on UC emission properties of Er3+ were investigated systemically. As a result, the emission intensity of 2 H11/2- 4 I15/2 in IOPC was found to be suppressed 37.4%, and the radiative lifetimes of 4 S3/2- 4 I15/2 were prolonged 1.55 times. The effects of the doping concentration on the reciprocal of fluorescence lifetimes of 4 S3/2- 4 I15/2 between the IOPC and the reference (REF) samples showed that the cross-energy transfer (CET) rate and the electronic transition rate were greatly inhibited, which could be due to the effect of the modulation of the effective index on the radiative transition rate and on the decrease of nonradiative transition rate caused by periodic thin-walled structure of IOPC. The power-dependent UC emission properties validated the supposition that the IOPC structure could be effectively suppressed the local thermal effect and thermal quenching. This research presents a further step in the exploration of the new kind of UCL materials with high luminous efficiency.

Thermally Robust Porous Bimetallic (Ni_<i>x</i>Pt_1-<i>x</i>) Alloy Mesocrystals within Carbon Framework: High-Performance Catalysts for Oxygen Reduction and Hydrogenation Reactions

Sohn, Hiesang,Xiao, Qiangfeng,Seubsai, Anusorn,Ye, Youngjin,Lee, Jinwoo,Han, Hyokyung,Park, Sehkyu,Chen, Gen,Lu, Yunfeng American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.24

<P>Thermally stable porous bimetallic (Ni<SUB><I>x</I></SUB>Pt<SUB>1-<I>x</I></SUB>) alloy mesocrystals within a carbon framework are produced via an aerosol-assisted process for high-performance catalysts for the oxygen reduction reaction (ORR) and hydrogenation. The porous Ni<SUB><I>x</I></SUB>Pt<SUB>1-<I>x</I></SUB> alloy has a robust composite of alloy nanoparticles with an adjustable composition and a porous carbon skeleton. Porous Ni<SUB><I>x</I></SUB>Pt<SUB>1-<I>x</I></SUB> alloys exhibit high thermal stability, retaining their crystalline structure and morphology at 550 °C for 6 h, as observed in thermal treatment tests under various conditions (time, temperature, and atmosphere). The porous Ni<SUB><I>x</I></SUB>Pt<SUB>1-<I>x</I></SUB> alloy as a catalyst for the hydrogenation of propylene has high conversion efficiency (>80%) and low activation energy (<I>E</I><SUB>a</SUB> < 20 kJ/mol) at ≥80 °C through the suitable control of the element composition and a pore structure. As a catalyst for the ORR, the catalytic activity of the porous Ni<SUB><I>x</I></SUB>Pt<SUB>1-<I>x</I></SUB> alloy is superior to that of conventional Pt/C (0.115 mA) (0.853 mA/cm<SUB>Pt</SUB><SUP>2</SUP> at 0.9 V/cm<SUB>Pt</SUB><SUP>2</SUP>). This is attributed to the homogeneous alloying of the metal components (Ni and Pt) and the increased accessibility of the reactants to the catalyst, resulting from the unique morphology of the porous Ni<SUB><I>x</I></SUB>Pt<SUB>1-<I>x</I></SUB> alloy, i.e., hierarchical structure with high porosity.</P> [FIG OMISSION]</BR>

Experimental and Numerical Investigation on the Cyclic Behavior of SRC Columns considering Unsymmetrical Confinement Effect

Xianpan Liu,Lei Zeng,Yunfeng Xiao,Yanhua Liu,Heng Zhang,Yun Cao 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.4

Experimental and numerical studies were conducted on the cyclic behavior of steel reinforced concrete (SRC) columns with T-shaped and L-shaped steel section. A total of 8 SRC columns were tested under axial compression and lateral cyclic loading. The design details, loading procedure and main results, including the failure modes, hysteretic characteristics and ductility were reported. Four failure modes as flexural failure, shear bond failure, shear compression failure and shear compound failure were observed. By considering various unsymmetrical confinement and plastic hinge region, the experimental study was supplemented by numerical analysis to study the influence of axial compression ratio, shear-span ratio and concrete strength. The results revealed that the FEA is in good agreement with the experimental results. The ultimate loading of specimen with confinement effect has been improved by 21.4% − 33.8%. The failure modes is dominated by the shear-span ratio and type of cross section. The specimens with smaller shear-span ratio are prone to shear failure, while the unsymmetrical steel arrangement causes shear compound failure which is combined with shear bond failure and shear compression failure. Moreover, the specimens with larger shear-span ratio and stirrup ratio present greater deformation capacity and ductility. In practical engineering, the confinement degree of SRC columns with unsymmetrical steel section can be enhanced by increasing the stirrup ratio and arranging the cross ties.

Robust lithium-ion anodes based on nanocomposites of iron oxide-carbon-silicate

Sohn, Hiesang,Chen, Zheng,Jung, Yoon Seok,Xiao, Qiangfeng,Cai, Mei,Wang, Haiqiang,Lu, Yunfeng The Royal Society of Chemistry 2013 Journal of materials chemistry. A, Materials for e Vol.1 No.14

Ficolin2 defends against virulent Mycobacteria tuberculosis infections in vivo and its insufficiency is associated with infections in human

Fengling Luo,Yubin Wang,Xiaoming Sun,Qilong Wang,Yunfeng Ma,Qin Pan,Xiao-Lian Zhang 한국당과학회 2012 한국당과학회 학술대회 Vol.2012 No.1

Tuberculosis (TB) caused by Mycobacterium tuberculosis (M.tb) remains a major global health problem. Human ficolin2 (L-ficolin/P35) is a recently identified lectin complement pathway activator present in normal plasma associated with infectious diseases, however, little is known about the roles and mechanisms of ficolin2 during M.tb infection.We describe in this study for the first time L-ficolin expression levels in tuberculosis (TB) patients. We found that serum levels of ficolin2 of 107 pulmonary TB patients were much lower compared with 107 healthy controls, and recurrence TB patients have even lower levels than onset TB patients. In vitro analysis showed that Ficolin2 bound to virulent M.tb H37Rv strain much stronger than to non-virulent M. bovis BCG and M. smegmatis. Ficolin2/ficolin A bound to the H37Rv surface glycolipid portion and blocked H37Rv infection to human lung A549 cells. We further determined that the extrogenous ficolin2 had remarkable protecting effects against virulent H37Rv strain infections in C57BL/6J mice. FicolinA (ficolin2 like molecule) knockout mice had greatly increased susceptibility to the H37Rv infection. Ficolin2 activated macrophages via phosphorylation of JNK and stimulated IFN-□, IL-17, TNF-□ and nitric oxide (NO) secretions. Ficolin2 also stimulated IFN-□ production of CD8+T cells, but not CD4+T cells. The opsono-phagocytosis was promoted by ficolin2 as well. Our data demonstrate that ficolin2 can defend against virulent M.tb H37Rv infection both in vitro and in vivo mainly via activating macrophage proinflammatory cytokines IFN-□ and NO production and opsonophagocytosis, and its insufficiency is associated with more susceptible infections in human.