Search

A compliant mechanism transmits motion and force by deformation of its flexible members. It has no relative moving parts and thus involves no wear, lubrication, noise, or backlash. Compliant mechanisms aim to maximize flexibility while maintaining sufficient stiffness so that satisfactory output motion may be achieved. When designing compliant mechanisms, the resulting shapes sometimes lead to rigid-body type linkages where compliance and rotation is lumped at a few flexural pivots. These flexural pivots are prone to stress concentration and thus limit compliant mechanisms to applications that only require small-deflected motion. To overcome this problem, a systematic design method is presented to synthesize the shape of a compliant mechanism so that compliance is distributed more uniformly over the mechanism. With a selected topology and load conditions, this method characterizes the free geometric shape of a compliant segment by its rotation and thickness functions. These two are referred as intrinsic functions and they describe the shape continuously within the segment so there is no abrupt change in geometry. Optimization problems can be conveniently formulated with cusps and intersecting loops naturally circumvented. To facilitate the optimization process, a numerical algorithm based on the generalized shooting method will be presented to solve for the deflected shape. Illustrative examples will demonstrate that through the proposed design method, compliant mechanisms with distributed compliance will lessen stress concentration so they are more robust and have a larger deflected range. It is expected that the method can be applied to design compliant mechanisms for a wide variety of applications. [DOI: 10.1115/1.2890117] Keywords: compliant mechanisms, shooting method, shape optimization, distributed compliance

Abstract: Aims: This study investigates the actions of KMUP-1 on RhoA/Rho-kinase (ROCK)-dependent Ca2+ sensitization and the K+-channel in chronic pulmonary arterial hypertension (PAH) rats. Main methods: Sprague–Dawley rats were divided into control, monocrotaline (MCT), and MCT+KMUP-1 groups. PAH was induced by a single intraperitoneal injection (i.p.) of MCT (60mg/kg). KMUP-1 (5mg/kg, i.p.) was administered once daily for 21days to prevent MCT-induced PAH. All rats were sacrificed on day 22. Key findings: MCT-induced increased right ventricular systolic pressure (RVSP) and right ventricular hypertrophy were prevented by KMUP-1. In myograph experiments, KCl (80mM), phenylephrine (10µM) and K+ channel inhibitors (TEA, 10mM; paxilline, 10µM; 4-AP, 5mM) induced weak PA contractions in MCT-treated rats compared to controls, but the PA reactivity was restored in MCT+KMUP-1-treated rats. By contrast, in β-escin- or α-toxin-permeabilized PAs, CaCl2-induced (1.25mM, pCa 5.1) contractions were stronger in MCT-treated rats, and this action was suppressed in MCT+KMUP-1-treated rats. PA relaxation in response to the ROCK inhibitor Y27632 (0.1μM) was much higher in MCT-treated rats than in control rats. In Western blot analysis, the expression of Ca2+-activated K+ (BKCa) and voltage-gated K+ channels (Kv2.1 and Kv1.5), and ROCK II proteins was elevated in MCT-treated rats and suppressed in MCT+KMUP-1-treated rats. We suggest that MCT-treated rats upregulate K+-channel proteins to adapt to chronic PAH. Significance: KMUP-1 protects against PAH and restores PA vessel tone in MCT-treated rats, attributed to alteration of Ca2+ sensitivity and K+-channel function. [Copyright &y& Elsevier]

Background: Postoperative radiotherapy (PORT) and concurrent chemoradiation (CCRT) are indicated for patients with advanced oral cancer. However, the benefits for pT1-2N1 disease without adverse pathological features are controversial., Methods: This retrospective study using the Taiwan Cancer Registry database included patients with pT1-2N1 oral cancer from January 1, 2011, to December 31, 2017. Overall survival was analyzed in patients receiving surgery alone, PORT, or CCRT., Results: Among the 862 patients, the five-year overall survival rate in patients receiving surgery alone, PORT, and CCRT was 62.2%, 58.7%, and 71.1% (P = 0.03), respectively. CCRT was associated with longer survival than PORT (P = 0.008). Survival in patients with pT2 disease was significantly higher with CCRT than PORT (P = 0.001), but no difference was observed in pT1 disease., Conclusion: CCRT demonstrated a favorable impact on survival outcomes in patients diagnosed with pT2N1 oral cancer when compared to PORT. However, no significant survival benefits were observed for patients with pT1 disease., Competing Interests: Declaration of competing interest Mu-Hung Tsai received research grants from Varian Medical Systems outside of the submitted work. The other authors declare no potential conflicts of interest., (Copyright © 2024 Formosan Medical Association. Published by Elsevier B.V. All rights reserved.)