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Preparation of Silver Metallic Sponge from Macroporous Carbon Template
Yan, Jia,Wang, An Jie,Kim, Dong Pyo Trans Tech Publications, Ltd. 2006 Materials science forum Vol.510 No.-
<P>Silver-containing porous frameworks have been extensively used in catalysis, electrochemistry, for heat dissipation and biofiltration. In this study, porous silver sponge was prepared by using a sacrificial macroporous carbon template. Aqueous AgNO3 was infiltrated into the carbon template and reduced to Ag by borohydride reduction reaction, followed by burning of the sacrificial template in air at 500~650°C. The products were characterized by SEM, XRD, and N2 adsorption-desorption isotherms. The Ag sponge exhibited a BET surface area of 12 m2/g.</P>
Design and behaviour of double skin composite beams with novel enhanced C-channels
Jia-Bao Yan,Huining Guan,Tao Wang 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.37 No.5
This paper firstly developed a new type of Double Skin Composite (DSC) beams using novel enhanced C-channels (ECs). The shear behaviour of novel ECs was firstly studied through two push-out tests. Eleven full-scale DSC beams with ECs (DSCB-ECs) were tested under four-point loading to study their ultimate strength behaviours, and the studied parameters were thickness of steel faceplate, spacing of ECs, shear span, and strength of concrete core. Test results showed that all the DSCB-ECs failed in flexure-governed mode, which confirmed the effective bonding of ECs. The working mechanisms of DSCB-ECs with different parameters were reported, analysed and discussed. The load-deflection (or strain) behaviour of DSCB-ECs were also detailed reported. The effects of studied parameters on ultimate strength behaviour of DSCB-ECs have been discussed and analysed. Including the experimental studies, this paper also developed theoretical models to predict the initial stiffness, elastic stiffness, cracking, yielding, and ultimate loads of DSCB-ECs. Validations of predictions against 11 test results proved the reasonable estimations of the developed theoretical models on those stiffness and strength indexes. Finally, conclusions were given based on these tests and analysis.
Jia-Bao Yan,J.Y. Richard Liew,Min-Hong Zhang,Junyan Wang 국제구조공학회 2014 Steel and Composite Structures, An International J Vol.17 No.6
Ultra-lightweight cement composite (ULCC) with a compressive strength of 60 MPa and density of 1450 kg/m³ has been developed and used in the steel-concrete-steel (SCS) sandwich structures. ULCC was adopted as the core material in the SCS sandwich composite beams to reduce the overall structural weight. Headed shear studs working in pairs with overlapped lengths were used to achieve composite action between the core material and steel face plates. Nine quasi-static tests on this type of SCS sandwich composite beams were carried out to evaluate their ultimate strength performances. Different parameters influencing the ultimate strength of the SCS sandwich composite beams were studied and discussed. Design equations were developed to predict the ultimate resistance of the cross section due to pure bending, pure shear and combined action between shear and moment. Effective stiffness of the sandwich composite beam section is also derived to predict the elastic deflection under service load. Finally, the design equations were validated by the test results.
Jia-Yan Liu,Gao-Wei Zheng,Tadayuki Imanaka,Jian-He Xu 한국생물공학회 2014 Biotechnology and Bioprocess Engineering Vol.19 No.3
Optically pure 1-(3’,4’-methylenedioxyphenyl)ethanol is a key chiral intermediate for the synthesis ofSteganacin and Salmeterol. A para-nitrobenzyl esterasecloned from Bacillus amyloliquefaciens (BAE) was employedto hydrolyze 1-(3’,4’-methylenedioxyphenyl) ethyl ester forthe production of (R)-1-(3’,4’-methylenedioxyphenyl)ethanol. Initially, a moderate enantioselectivity (E = 35) only wasobtained at 30°C. Some reaction conditions such asreaction temperature and additive approach were investigatedin order to improve the enantioselectivity of the BAEcatalyzedreaction.. As a result, the enantioselectivity wasimproved significantly to 140 under addition of Tween-80and a decreasing reaction temperature to 0°C. The resultwas confirmed in a decagram-scale preparative bioresolutionalso. The optimized enzymatic hydrolysis conditions providea more effective process for the (R)-1-(3’,4’-methylenedioxyphenyl)ethanol bioproduction.
Flexural performance of double skin composite beams at the Arctic low temperature
Jia-Bao Yan,Xin Dong,Tao Wang 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.37 No.4
This paper presents the flexural performance of double skin composite beams (DSCBs) at different Arctic low temperatures. 12 DSCBs were prepared and tested under two-point loading at different Arctic low temperatures of 20, -30, -50, and -70°C. The studied parameters include low-temperature level (T), steel-faceplate thickness (t), shear span ratio (λ), and spacing of headed studs (S). The experimental investigations under two-point loading tests showed that flexural failure occurred to all DSCBs, even including the specimen designed with the small λ ratio of 2.9. The ultimate strength behaviours of DSCBs were improved due to the improved mechanical properties of constructional materials and the confinement on shear connectors. The DSCB subjected to two-point loading and low temperatures exhibits a five-stage working mechanism. The stiffness and strength indexes of DSCBs increase linearly with temperature and t value increasing, while decreasing as shear span ratio boosts. In the contrast, the change of S value from 150 to 200 mm has little effect on the ultimate strength behavior of DSCB.
Shear and tensile behaviors of headed stud connectors in double skin composite shear wall
Jia-Bao Yan,Zhe Wang,Tao Wang,Xiao-Ting Wang 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.26 No.6
This paper studies shear and tensile behaviors of headed stud connectors in double skin composite (DSC) structure. Firstly, 11 push-out tests and 11 tensile tests were performed to investigate the ultimate shear and tensile behaviors of headed stud in DSC shear wall, respectively. The main parameters investigated in this test program were height and layout of headed stud connectors. The test results reported the representative failure modes of headed studs in DSC structures subjected to shear and tension. The shear-slip and tension-elongation behaviors of headed studs in DSC structures were also reported. Influences of different parameters on these shear-slip and tension-elongation behaviors of headed studs were discussed and analyzed. Analytical models were also developed to predict the ultimate shear and tensile resistances of headed stud connectors in DSC shear walls. The developed analytical model incorporated the influence of the dense layout of headed studs in DSC shear walls. The validations of analytical predictions against 22 test results confirmed the accuracy of developed analytical models.
Tensile behavior of stainless steel S30408 at the Arctic low temperature
Jia-Bao Yan,Zhicheng Lin,Peng Xie,Yun-Biao Luo,Yanbo Li 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.40 No.5
This paper investigated tensile behaviours of S30408 at the Arctic low temperatures (T) of -80~20℃. A cooling chamber equipped with liquid nitrogen gas was adopted to rebuild the Arctic low-temperature environment. Standard tension tests were performed on 48 coupons with different thickness at different T values of -80, -60, -30, and 20℃. Test results revealed the ductile failure mode of stainless steel S30408 even at -80℃. The tensile stress-strain (σ-ε) curves of S30408 at ambient temperatures exhibited a long strain hardening plateau. Meanwhile, the low-temperature tensile σ-ε curves of S30408 were different from those at ambient temperatures, which exhibited a second hardening stage with a larger slope than the first hardening. The decreasing T generally increased the elastic modulus, yield and ultimate strength, but reduced the ductility of S30408. Decreasing the T from 20 to -80℃ reduced the ductility of S30408 by about 28%, but improved the elastic modulus, yield and ultimate strength by about 20%, 22%, and 75%, respectively. This paper also adopted the best subset regression analysis method to develop empirical formulae on estimating influences of T on mechanical properties of S30408. Validations of the predictions by these empirical formulae against the test results in the literature proved their accuracies.
Behaviors of novel sandwich composite beams with normal weight concrete
Jia-Bao Yan,Xin Dong,Tao Wang 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.38 No.5
The ultimate strength behaviour of sandwich composite beams with J-hooks and normal weight concrete (SCSSBJNs) are studied through two-point loading tests on ten full-scale SCSSBJNs. The test results show that the SCSSBJN with different parameters under two-point loads exhibits three types of failure modes, i.e., flexure, shear, and combined shear and flexure mode. SCSSBJN failed in different failure modes exhibits different load-deflection behaviours, and the main difference of these three types of behaviours exist in their last working stages. The influences of thickness of steel faceplate, shear span ratio, concrete core strength, and spacing of J-hooks on structural behaviours of SCSSBJN are discussed and analysed. These test results show that the failure mode of SCSSBJN was sensitive to the thickness of steel faceplate, shear span ratio, and concrete core strength. Theoretical models are developed to estimate the cracking, yielding, and ultimate bending resistance of SCSSBJN as well as its transverse cross-sectional shear resistance. The validations of predictions by these theoretical models proved that they are capable of estimating strengths of novel SCSSBJNs.