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Ultrasonic-assisted ball burnishing (UABB) is a promising surface strengthening technology for improving the properties of components. This method superimposes ultrasonic vibration to the traditional deep rolling; it can improve the surface roughness of a material, enhance its surface hardness, and introduce a high compressive residual stress, thereby improving the fatigue performance of components. A mathematical model should be established to predict and analyze the relationship between the experimental process parameters and results and to predict the effect of UABB on surface roughness. In the present work, a mathematical model of surface roughness after UABB was established on the basis of Hertz contact theory, comprehensively considering the process parameters, dynamic vibration forces, and elastic rebound of the targets. UABB experiments were carried out to verify the correctness of the mathematical model. Results showed that UABB can significantly reduce the surface roughness of the material, and the values calculated from the derived mathematical model showed good agreement with the experimental findings. The surface roughness decreased with the burnishing force (50–250 N) and amplitude (4–10 μm) increased, whereas the feed rate decreased. The increases of radii of component and ball were detrimental to the improvement of the surface roughness. And elastic rebound was not conducive to roughness reduction and its influence was negligible. Finally, the derived surface roughness model can be used to predict the component values after UABB and understand the effects of machining parameters on the shaft targets during processing.

The ultrasonic-assisted burnishing process (UABP) is an effective surface finishing technology that obtains compressive residual stress and surface work hardening and decreases surface roughness. A three-dimensional explicit nonlinear finite element model (FEM) of the UABP on a shaft specimen was established and calibrated in this paper. A comparison of finite element (FE) simulation results with experimental data showed good agreement in terms of the predicted residual stress in both tangential and axial directions. The established FEM explores the influence of treatment parameters, such as ball diameters, static forces, spindle speeds, ultrasonic frequencies, vibration amplitudes, and friction coefficients, on the resultant profile of residual stress and equivalent plastic deformation. This dynamic explicit FE method is an effective approach to investigate the UABP, to relate the processing parameters with surface integrity, including the depth of residual stress and work hardening of objective surfaces, and to guide the design of the UABP parameters.

Keratin has the potential to improve biocompatibility and bioactivity of polymeric nanofibers. However, the addition of keratin into the blend nanofiber would decrease the mechanical properties of nanofibers due to the poor spinnability of keratin, and caused inhomogeneous distribution of keratin inside the nanofibers. Therefore, polymeric nanofibers surface-modified with keratin nanoparticles would improve the hydrophility and mechanical property. In this study, keratose (oxidative keratin, KOS) nanoparticles-coating PVA nanofibers (KNPs/PVA) were fabricated by electrospray deposition after electrospinning and acted on neural cells. The chemical conformation, mechanical properties and wettability of KNPs/PVA nanofibers were characterized. The KNPs/PVA nanofibers provided better wettability and stronger mechanical properties compared to KOS/PVA blend nanofibers at the same mass ratio of KOS to PVA. Furthermore, KNPs/PVA nanofibers displayed better cyto-biocompatibility in terms of cell morphology, adhesion and proliferation compared with PVA nanofibers and KOS/PVA blend nanofibers. These results suggested that polymeric nanofibers surface-modified with KOS nanoparticles can provide superior wettability, mechanical properties and biocompatibility by comparison with the blend nanofibers.

Pharmaceutically active compounds in wastewater released from human consumption have received considerable attention because of their possible risks for aquatic environments. In this study, the occurrence and removal of 10 pharmaceuticals in three municipal wastewater treatment plants in southern China were investigated and the environmental risks they posed were assessed. Nifedipine, atenolol, metoprolol, valsartan and pravastatin were detected in the influent wastewater. The highest average concentration in the influents was observed for metoprolol (164.6 ng/L), followed by valsartan (120.3 ng/L) in August, while median concentrations were higher in November than in August. The total average daily mass loadings of the pharmaceuticals in the three plants were 289.52 mg/d/person, 430.46 mg/d/person and 368.67 mg/d/person, respectively. Elimination in the treatment plants studied was incomplete, with metoprolol levels increasing during biological treatment. Biological treatment was the most effective step for PhACs removal in all of the plants studied. Moreover, the removal of PhACs was observed with higher efficiencies in August than in November. The WWTP equipped with an Unitank process exhibited similar removals of most PhACs as other WWTPs equipped with an anoxic/oxic (A/O) process or various anaerobic-anoxic-oxic (A2/O) process. The environmental risk assessment concluded that all of the single PhAC in the effluents displayed a low risk (RQ

Chitosan–clinoptilolite composite was prepared and tested for removing radiocobalt from aqueous solution. The composite was characterized with Fourier transform infrared spectroscopy, X-ray diffraction analysis and scanning electron microscopy coupled with energy dispersive X-ray analysis. The sorption of Co(II) on chitosan–clinoptilolite composite was pH-dependent and ionic strength-independent. The kinetic sorption was fitted well by a pseudo-second-order rate equation. The thermodynamic parameters (ΔH 0, ΔS 0, ΔG 0) revealed that the sorption of Co(II) on chitosan–clinoptilolite composite was spontaneous and endothermic. The study showed that chitosan–clinoptilolite composite had excellent potential for the treatment of wastewater containing radiocobalt.

A systematic investigation of the transport of 125I in compacted GMZ bentonite containing Fe-Oxides, Fe-minerals or Cu2O additive was carried out by through-diffusion method. The obtained results indicate that all of the additives have positive effects on retarding the 125I diffusion in compacted GMZ bentonite. Especially for the Cu2O additive, the corresponding effective diffusion coefficient is greatly reduced. It is mainly attributed to the particular interactions between the metal ions introduced by additives and iodide ions.