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The driving mechanism of an axisymmetric vectoring exhaust nozzle (AVEN) is a 3-degrees-of-freedom (3-DOF) parallel manipulator (PM) with a centering device. According to the characteristics of the vectoring nozzle's movement mechanism, the 3-DOF kinematics model of the 3SPS + 3PRS PM is established. The forward and inverse positional posture models are built based on the mechanism architecture of PM and the closed-loop vector method. The Jacobian matrix and Hessian matrix are derived using screw theory, and velocity and acceleration models are established. Based on the principle of virtual work and combined with the kinematics model of PM, a stiffness model was established to analyze stiffness performance. Finally, the effectiveness of the kinematics model of the PM was verified by a simulation, and the variation of stiffness performances with the positional posture of the PM was quantitatively analyzed. The results show that the translational stiffness decreases with forward axial translation of the moving platform and the rotational stiffness is mainly determined by the posture parameters. This study is expected to offer ideas for the kinematic modeling of 3-DOF PM and provide references for application and optimizing of the AVEN's driving mechanism. [ABSTRACT FROM AUTHOR]

We aimed to determine factors influencing lymph node metastasis (LNM) and develop a more effective method to assess preoperative N staging. Overall, data of 2130 patients who underwent thyroidectomy for thyroid cancer between 2018 and 2021 were retrospectively analysed. Patients were divided into groups according to pN0, pN1a, and pN1b stages. Pathology was used to analyse the correlation between preoperative serum marker indicators and LNM. Receiver operating characteristic curves were used to compare the diagnostic value of ultrasound (US) examination alone, serum thyroglobulin, age, and combined method for LNM. A significant moderate agreement was observed between preoperative US and postoperative pathology for N staging. Between the pN0 and pN1 (pN1a + pN1b) groups, the differences in free triiodothyronine, anti-thyroid peroxidase antibody, and serum thyroglobulin levels were statistically significant. Among the indicators, serum thyroglobulin was an independent predictor of LNM. The area under the receiver operating characteristic curve was 0.610 for serum thyroglobulin level for predicting LNM, 0.689 for US alone, and 0.742 for the combined method. Both preoperative US and serum thyroglobulin level provide a specific value when evaluating the N staging of thyroid cancer, and the combined method is more valuable in the diagnosis of LNM than US alone. [ABSTRACT FROM AUTHOR]

In order to study the influence of compliance parts on spatial multibody systems, a rigid-flexible coupling dynamic equation of a spatial crank-slider mechanism is established based on the finite element method. Specifically, absolute node coordinate formulation (ANCF) is used to formulate a three-dimensional, two-node flexible cable element. The rigid-flexible coupling dynamic equation of the mechanism is derived by the Lagrange multiplier method and solved by the generalized α method and Newton–Raphson iteration method combined. Comparison of the kinematics and dynamics response between rigid-flexible coupling system and pure rigid system implies that the flexible part causes a certain degree of nonlinearity and reduces the reaction forces of joints. The elastic modulus of the flexible part is also important to the dynamics of the rigid-flexible multibody system. With smaller elastic modulus, the motion accuracy and reaction forces become lower. [ABSTRACT FROM AUTHOR]

Background: White adipose tissue (WAT) browning confers beneficial effects on metabolic diseases. However, visceral adipose tissue (VAT) is not as susceptible to browning as subcutaneous adipose tissue (SAT). Aim: Interpreting the heterogeneity of VAT and SAT in brown remodeling and provide promising lipid targets to promote WAT browning. Methods: We first investigated the effects of β3-adrenergic stimulation by CL316,243 on systemic metabolism. Then, high-coverage targeted lipidomics approach with multiple reaction monitoring (MRM) was utilized to provide extensive detection of lipid metabolites in VAT and SAT. Results: CL316,243 notably ameliorated the systemic metabolism and induced brown remodeling of SAT but browning resistance of VAT. Comprehensive lipidomics analysis revealed browning heterogeneity of VAT and SAT with more dramatic alteration of lipid classes and species in VAT rather than SAT, though VAT is resistant to browning. Adrenergic stimulation differentially affected glycerides content in VAT and SAT and boosted the abundance of more glycerophospholipids species in VAT than in SAT. Besides, CL316,243 increased sphingolipids in VAT without changes in SAT, meanwhile, elevated cardiolipin species more prominently in VAT than in SAT. Conclusions: We demonstrated the browning heterogeneity of WAT and identified potential lipid biomarkers which may provide lipid targets for overcoming VAT browning resistance. [ABSTRACT FROM AUTHOR]