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Six brick masonry specimens (two unreinforced specimens, two reinforced specimens, and two specimens reinforced after being damaged), which have different aspect ratios, were tested under low-frequency cyclic loading. The seismic performances of these specimens, including failure characteristics, deformation capacity, carrying capacity, energy dissipation capacity, hysteresis characteristics, and stiffness degradation, were analyzed. The following results were obtained: the ductility of the damaged walls could be significantly improved after they were reinforced with embedded horizontal steel bars; the ultimate shear capacity of the damaged brick masonry walls with the aspect ratios of 1.8 and 0.5 was improved by 6.8% and 4.7%, respectively; the displacement corresponding to the ultimate bearing capacity was close to that of the unreinforced brick masonry wall; the hysteresis loop of the reinforced wall became plumper and encompassed a larger area; after the ultimate load was reached, a clear yielding platform appeared in the skeleton curve of the reinforced wall; the reinforced wall exhibited good ductility, after entering plastic stage; the energy dissipation capacity of the reinforced wall was significantly greater than that of the unreinforced wall. In conclusion, the seismic performance of the damaged brick masonry wall can be improved by embedding horizontal steel bars, and this reinforcing method can be applied in the postseismic reconstruction process.

Robot-assisted minimally invasive surgery (MIS) has shown tremendous advances over the traditional technique. A crucial challenge for developing a MIS robot is the kinematic design of the remote center-of-motion (RCM) mechanism. In this paper, a class of spatial RCM mechanism is analyzed. They are obtained by generating virtual parallelograms. The main process is to construct a line that passes through a fixed point under the mechanical constraint. The axis of the surgical tool is then constrained to parallel with that line. Hence, due to the geometrical feature of the parallel lines, the axis of the surgical tool will always pass through a fixed point, i.e., the RCM point. Due to the specially designed structure, the fixed point does not need to be physically belonging to the mechanism. The geometrical analysis method is employed to obtain the closed-form solution of the forward kinematics of the proposed mechanisms. Due to the high load capacity of parallel mechanism, the robots based on the proposed RCM mechanisms have promising applications as an external positioner to be used in robotic single-port surgeries. [ABSTRACT FROM AUTHOR]

270 steel bars with different diameters of 12, 14 and 16 are accelerated to corrode in 5% chloride solution, 5% sulfate solution and 5% halogen solution by DC voltage stabilization. A different age periods, the quality is weighed by high precision balance, the steel bar is stretched by electronic universal testing machine, and the corrosion rate, yield strength, ultimate tensile strength and elongation are measured. The test data show that the chloride solution in the three solutions has the strongest corrosion, and the corrosion rate of 15% is the critical point of yield strength. When it exceeds the critical point, the yield platform disappears, showing obvious brittleness, and the elongation decreases. On the basis of the mechanism of steel corrosion, the mathematical model of the thickness of steel corrosion layer, the constitutive relationship of the three-stage theory and the two-stage wheel of steel corrosion are obtained. At the same time, the linear relationship between elongation, corrosion rate and ultimate tensile strength of steel bar is found, and the degradation law of mechanical properties of corroded steel bar is further obtained. [ABSTRACT FROM AUTHOR]

To improve the disadvantage of the low reactivity and reduce the high curing temperature of epoxy resin cured by dicyandiamide (DICY), DICY is chemically modified with phenyl hydrazine and a new curing agent, LB-A, is developed in this research. The structure, the curing behavior, and reaction kinetics of LB-A curing epoxy resin are investigated. Results show that the DICY is modified successfully and the well-defined structure of DICY is destroyed after modification. Consequently, a new curing agent in a noncrystal form is resulted. Thereupon, the reactivity and compatibility between the epoxy resin and the curing agent are improved appreciably using LB-A instead of DICY. Meanwhile, the curing temperature and activation energy of the curing reaction decrease outstanding, whereas the rate constant increases remarkably. In addition, the compressive strength and the adhesive strength in shear by tension loading of the resulting epoxy resins have been increased using LB-A instead of DICY as the curing agent. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

In this study, an amidoxime-appended zirconium metal-organic framework [Zr 6 O 4 (OH) 4 (BDC-NHCH 2 CH 2 C(=N–OH)NH 2) 6 ](UiO-66-AO, BDC = 1,4-benzenedicarboxylate) for efficiently and rapidly removing uranium from aqueous solution was fabricated through post-modifications. The chemical structure and composition of original and modified UiO-66 MOFs were investigated in detail. The principal factors affecting the adsorption of U(VI) ions have been investigated, including pH of the aqueous solution, contact time, temperature, and coexisting cations through batch adsorption experiments. The adsorption kinetics conformed to the pseudo-second-order model. It was found that the maximum adsorption capacity reached 232.8 mg/g at pH 5.0 and 328 K based on the Langmuir isotherm. The thermodynamics parameters revealed that this adsorption process was spontaneous and endothermic. The sorption experiment in a simulated nuclear industry effluent demonstrated a high adsorption efficiency (about 95.3%) and selectivity toward uranium. The extended X-ray absorption fine structure (EXAFS) analysis revealed the coordination mechanism of amidoxime-appended UiO-66 and uranyl. [Display omitted] • Amidoxime was first grafted on UiO-66-NH 2 via acrylonitrile. • The amidoxime-appended UiO-66 MOFs exhibited high adsorption capacity and selectivity for uranium. • The adsorption mechanism of UiO-66-AO and uranyl was investigated by EXAFS. [ABSTRACT FROM AUTHOR]