Modeling and Experimental Study of the Localized Electrochemical Micro Additive Manufacturing Technology Based on the FluidFM

In this work, the localized electrochemical micro additive manufacturing technology based on the FluidFM (fluidic force microscope) has been introduced to fabricate micro three-dimensional overhang metal structures at sub-micron resolution. It breaks through the localized deposition previously achieved by micro-anode precision movement, and the micro-injection of the electrolyte is achieved in a stable electric field distribution. The structure of electrochemical facilities has been designed and optimized. More importantly, the local electrochemical deposition process has been analyzed with positive source diffusion, and the mathematical modeling has been revealed in the particle conversion process. A mathematical model is proposed for the species flux under the action of pulsed pressure in an innovatively localized liquid feeding process. Besides, the linear structure, bulk structure, complex structure, and large-area structure of the additive manufacturing are analyzed separately. The experimental diameter of the deposited cylinder structure is linearly fitted. The aspect ratio of the structure is greater than 20, the surface roughness value is between 0.1–0.2 μm at the surface of bulk structures, and the abilities are verified for deposition of overhang, hollow complex structures. Moreover, this work verifies the feasibility of 3D overhang array submicron structure additive manufacturing, with the application of pulsed pressure. Furthermore, this technology opens new avenues for the direct fabrication of nano circuit interconnection, tiny sensors, and micro antennas

A scalable method toward robust underwater superoleophobic surfaces with microstructure arrays on 304 stainless steel substrates

Underwater superoleophobic surfaces have huge application prospects due to their multiple functions such as antifouling, self-cleaning, manipulation of oil microdroplets, and oil − water separation. However, efficient and low-damage methods for the scalable fabrication of robust underwater superoleophobic surfaces on stainless steel substrates are still lacking. Here, a maskless electrochemical machining technology was developed to fabricate robust underwater superoleophobic surfaces on 304 stainless steel substrates. The square micro pit array was obtained on the surface, and the surface showed excellent superoleophobicity with a contact angle of 154.93 ± 1.42° when submerged in water. In addition, the fabricated underwater superoleophobic surface with the square micro pit array showed good chemical stability, mechanical stability, and anti-friction performance. The friction coefficient of the fabricated underwater superoleophobic surface was 0.0748, which was 60.7% lower than the friction coefficient of a smooth surface. Compared with traditional methods, the proposed technology will promote the practical applications of underwater superoleophobic surfaces in complex underwater environments

Green fabrication of anti-friction slippery liquid-infused metallic surface with sub-millimeter-scale asymmetric bump arrays and its application

In this work, we present a simple technique for green fabrication of slippery liquid-infused surface (SLIS) with anti-friction property on various metallic substrates using wire electrical discharge machining. Micro-crater structures were successfully obtained, and the surface had excellent liquid-repellent property after modification and infusion of silicone oil. A wide range of liquids including water, juice, coffee, tea, vinegar, albumin, glycerol, and ketchup could easily slid down the surface tilted at an angle of 10° without leaving any trace. The influences of the number of cutting step on the morphology and wettability of the surface were studied comprehensively. Further, the tribological properties of the surface were analyzed and the results showed that the SLIS had a decrease of 73.2% in friction coefficient as compared to that of the smooth surface. By studying the morphology of the worn surfaces, it is found that the SLIS had slight abrasive wear behavior. To demonstrate the precision processing ability of this technology, we fabricated slippery sub-millimeter-scale asymmetric bump arrays, and the experiment results showed that the asymmetric bump arrays had excellent water harvesting ability at low temperatures. This kind of environment-friendly precision machining technology will promote the practical applications of metallic functional materials

Prevalence and influencing factors of anxiety and depression symptoms among surgical nurses during COVID-19 pandemic: A large-scale cross-sectional study

Aim:To evaluate the prevalence and influencing factors of anxiety and depression symptoms in surgical nurses during the COVID-19 epidemic in Anhui, China.Methods:A cross-sectional, multic'entre quantitative study was conducted among surgical nurses in Anhui province. SAS, SDS and SSRS scales were used for the investigation. Data were collected between 3 March 2020 to 19 March 2020.Results:A total of 3,492 surgical nurses completed the survey. The average level of anxiety and depression of surgical nurses were higher than that of the Chinese norm. Levels of social support for surgical nurses were significantly negatively associated with the degree of anxiety and depression. Fertility status, participation in care for COVID-19 patients, likelihood of being infected with COVID-19 and social support were significantly influencing surgical nurses’ anxiety degree. Similarly, these characteristics were significantly associated with the odds of depression symptoms in surgical nurses.Conclusion:These findings suggest that targeted psychological interventions to promote mental health of surgical nurses need to be immediately implemented