Evaluation of a Commercial MoS2 Dry Film Lubricant for Space Applications

Molybdenum disulfide coatings, particularly Microseal 200-1, have been extensively used as dry film lubricants for actuating mechanisms in space applications. Although Microseal 200-1 has historically been a popular choice for space missions, recent assessments indicate a need for reexamination. This study evaluates sliding friction in air and dry gaseous nitrogen atmospheres at ambient temperatures with both linear reciprocating and rotary unidirectional tribo-tests. Measurements are performed for Microseal 200-1 applied on substrates and surface treatments commonly used in aerospace components, particularly stainless steel and a titanium alloy. Our findings indicate that the friction of stainless steel balls sliding on Microseal 200-1-coated disks is significantly influenced by the environment as well as the disk substrate material. The average friction coefficient ranges from 0.12 to 0.48 in air and from 0.04 to 0.41 in dry gaseous nitrogen, and the amount of friction is consistently much higher for the Microseal 200-1 on the stainless steel than on the titanium alloy. Microscopy and surface analyses, including scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray fluorescence, of the coatings on stainless steel substrates reveals that the coatings are sparse and relatively thin, likely a key factor contributing to their high friction. This insight underscores the substrate dependence of this widely used coating and highlights the importance of detailed tribological testing in accurately assessing the tribological performance of commercial dry film lubricants, a key step towards improving the reliability and effectiveness of actuating mechanisms for space applications

Feasibility of Surgeon-Delivered Audit and Feedback Incorporating Peer Surgical Coaching to Reduce Fistula Incidence following Cleft Palate Repair: A Pilot Trial

Background: Improving surgeons\u27 technical performance may reduce their frequency of postoperative complications. The authors conducted a pilot trial to evaluate the feasibility of a surgeon-delivered audit and feedback intervention incorporating peer surgical coaching on technical performance among surgeons performing cleft palate repair, in advance of a future effectiveness trial. Methods: A nonrandomized, two-arm, unblinded pilot trial enrolled surgeons performing cleft palate repair. Participants completed a baseline audit of fistula incidence. Participants with a fistula incidence above the median were allocated to an intensive feedback intervention that included selecting a peer surgical coach, observing the coach perform palate repair, reviewing operative video of their own surgical technique with the coach, and proposing and implementing changes in their technique. All others were allocated to simple feedback (receiving audit results). Outcomes assessed were proportion of surgeons completing the baseline audit, disclosing their fistula incidence to peers, and completing the feedback intervention. Results: Seven surgeons enrolled in the trial. All seven completed the baseline audit and disclosed their fistula incidence to other participants. The median baseline fistula incidence was 0.4 percent (range, 0 to 10.5 percent). Two surgeons were unable to receive the feedback intervention. Of the five remaining surgeons, two were allocated to intensive feedback and three to simple feedback. All surgeons completed their assigned feedback intervention. Among surgeons receiving intensive feedback, fistula incidence was 5.9 percent at baseline and 0.0 percent following feedback (adjusted OR, 0.98; 95 percent CI, 0.44 to 2.17). Conclusion: Surgeon-delivered audit and feedback incorporating peer coaching on technical performance was feasible for surgeons

3D Printing and Surgical Simulation for Management of Large and Giant Congenital Melanocytic Nevi

Summary:. Tissue expansion with subsequent adjacent tissue transfer is often the preferred and sometimes the only option for reconstruction of large and giant congenital melanocytic nevi. Successful reconstruction with maximal efficiency and optimal aesthetic outcome requires careful planning of the tissue transfer, which itself requires careful selection of the tissue expander size and positioning. Unfortunately, there is little opportunity to gain experience in these skills due to the rarity of this condition. In situations where there is a rare condition that requires a complex technical procedure with much interoperative decision-making, surgical experience can be supplemented with the use of surgical simulation. In this article, we report on the use of three-dimensional patient imaging, three-dimensional printing, and surgical simulation for planning the reconstruction of large and giant congenital melanocytic nevi. We describe how this technology allows us to simulate multiple different approaches to expander placement and adjacent tissue transfer. We also describe how these simulations can be used to create cutting guides to guide final incision design and reduce intraoperative decision-making. Finally, we discuss how these models can be used to educate patients and families about the process and outcomes of nevus excision and reconstruction