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This article reports on a flexible polymer electrolyte membrane fuel cell (PEMFC) with a pre-bent flow field. The performances in the flat and bent positions were lower and higher, respectively than that of the traditional flexible fuel cells. The low performance in the flat position was attributed to the void space induced incomplete contact at the interface of the membrane electrode assembly (MEA) and flow-field plates, which resulted in poor performance due to the high ohmic resistance (5.85 Ω cm 2 ) and faradaic resistance (4.17 Ω cm 2 ). However, when bending stress was applied to the MEA, a decreased ohmic resistance (0.954 Ω cm 2 ), faradaic resistance (0.737 Ω cm 2 ), and an enhanced power density (88.7 mW/cm 2 ) were observed because of the improved interfacial contact property between the MEA and the flow-field plates from the increased compressive stress. These experimental results were further analyzed and visualized with aid of the finite element analysis. Despite the relatively low performance in the flat shape, the proposed pre-bent design of the flexible PEMFC possesses promising applicability especially in flexible electronics where the curved shapes are highly required.

Background: Osteomas are benign, slow-growing bone tumors that can be classified as central, peripheral, or extraskeletal. Central osteomas arise from the endosteum, peripheral osteomas from the periosteum, and extraskeletal osteomas within the muscle. Frontal peripheral osteomas are mainly encountered in plastic surgery. In this study, we retrospectively analyzed the clinical data of patients with frontal peripheral osteomas.Methods: We retrospectively reviewed the medical records of patients who visited our hospital with frontal peripheral osteomas between January 2014 and June 2022. We analyzed the following variables: age, sex, tumor type (sessile or pedunculated), single or multiple, size, history of head trauma, operation, and recurrence.Results: A total of 39 patients and 41 osteomas were analyzed, of which 29 osteomas (71%) were sessile and 12 osteomas (29%) were pedunculated. The size of the osteomas ranged from 4 to 30 mm, with an average size of 10 mm. The age of patients ranged from 4 to 78 years with a mean age of 52 years. There were seven men (18%) and 32 women (82%), and the man-to-woman ratio was 1:4.6. Two patients (5%) had multiple masses, with two osteomas in each, while only two patients (5%) had a history of head trauma. Twenty-nine patients (74%) underwent ostectomy by a direct approach, and none of the patients experienced recurrence.Conclusion: The epidemiologic data of our study will help plastic surgeons encounter frontal peripheral osteomas in the field to provide proper management for their patients.