Chaosheng Wang

This study aimed to evaluate the feasibility of a “main renal artery + branches” ablation strategy for catheter-based circumferential ultrasonic renal denervation (uRDN), with a particular focus on thermal ablation morphology. We characterized peripheral tissues and nerves surrounding the renal artery at various locations and investigated the effects of the renal vein, adjacent arteries, lymph nodes, and ganglia, on the radial propagation of tubular ultrasound and measured their impact on the temperature field and ablation morphology. By correlating ablation morphology with nerve distribution features, we proposed optimized combinations of parameters for main renal artery and branch ablations. These combinations were validated through ex vivo experiments. The study found that the peripheral tissues of the renal artery significantly affect the field of tubular ultrasound. Specifically, veins and other arteries exhibited a greater impact on the thermal field compared to lymph nodes and ganglia. Based on the distribution characteristics of tissues and nerves at different locations, we derived combinations of ablation parameters covering approximately 90% of the nerves at various positions along the renal artery. For example, at an ultrasound power of 15 W, the ablation times needed for the proximal, distal, and first branches of the renal artery were 24 s, 16 s, and 9 s, respectively. Alternatively, at an ablation time of 18 s, the required powers were 19.5 W, 13 W, and 8.5 W, respectively. Ex vivo experiments revealed a deviation from the theoretical predictions of less than 2 °C. These combinations of parameters provide theoretical support for a “main renal artery + branches” ablation strategy in renal denervation surgery. Our findings suggest that the first-order renal artery branch is an optimal target for catheter-based circumferential ultrasonic renal denervation. An ablation radius of 2.5 mm is sufficient to effectively encircle 90% of the nerves, which minimizes energy consumption and procedural duration and prevents damage to surrounding tissues. This ablation strategy, which is based on the combination of the main renal artery and its first-order branch, represents a promising approach for effective renal denervation.

Escalating environmental concerns over nondegradable plastics have driven the development of biodegradable copolyesters for sustainable packaging. This study introduces a novel series of rigid-flexible poly(ester-carbonate)s (PBCCTs) synthesized by incorporating 1,4-butanediol (BDO) and trimethyl citrate (TMC) into a rigid framework. The synergistic integration of flexible BDO units, rigid cyclohexyl rings, and in situ three-armed branched architecture enhances chain entanglement, overcoming the mechanical-biodegradability trade-off in commercial copolyesters like PBAT. PBCCTs offer tunable high-performance with superior optical, mechanical, and degradation properties: tensile strengths of 20.1-35.3 MPa, elongation at break of 206.0-500.0%, and tear strength up to 104 N mm^-1. The preferential scission of aliphatic carbonate units at targeted degradation sites imparts markedly enhanced degradability to the copolyester, with PBCCT₇₀ showing a mass loss of 64.49 wt %. Hemolysis and cytotoxicity assays confirm excellent biocompatibility, positioning PBCCTs as promising materials for robust, sustainable packaging.

This study conducts a detailed viscoelastic simulation of the side-by-side PA6/PA66 bicomponent melt spinning process to investigate the mechanisms behind reduced fiber elasticity. A two-dimensional (2D) axisymmetric finite element model was developed using ANSYS Polyflow, incorporating the Phan–Thien–Tanner (PTT) constitutive equation and a non-isothermal crystallization model. Simulation outcomes were validated with experimental and published data, showing close agreement in fiber radius, velocity, and temperature profiles (within 8% deviation). Results indicate that the dominance of the higher-viscosity PA66 phase induces uneven stress distributions and localized crystallization, leading to decreased elastic recovery. Higher winding speeds amplify this effect. This work offers a predictive framework for optimizing industrial melt spinning conditions to improve elasticity in bicomponent fibers. Key results indicate that the dominance of the PA66 component—due to its higher melt viscosity—leads to uneven stress distribution, elevated tensile stress, and localized crystallinity peaks along the spin line. These factors collectively contribute to reduced elastic recovery in the fiber. Moreover, increased winding speeds amplify axial stress and crystallinity disparities, further exacerbating the stiffness of the final product. In contrast, better elasticity was associated with lower pressure drop, balanced crystallinity, and minimized axial velocity differences between the two polymer phases. The findings offer valuable insights into optimizing industrial melt spinning processes to enhance fiber elasticity. This research not only improves fundamental understanding of viscoelastic flow behavior in bicomponent spinning but also provides a predictive framework for tailoring mechanical properties of fibers through process and material parameter adjustments.