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Two-dimensional (2D) and three-dimensional (3D) numerical models are commonly employed to investigate the kinematic and hydrodynamic characteristics of fish maneuvers. In this study, we captured the posture characteristics of zebrafish during C-type maneuvers using high-speed photography and constructed a midline curvature model via the tandem principal characteristics method, which exhibited a "double peak and single valley" structure. Based on this curvature model, self-propelled simulations were conducted using the immersed boundary method with adaptive mesh refinement. The results showed that, under identical deformation conditions, the 2D simulation exhibited a 16.8% higher centroid velocity, 6.1% greater overall angular velocity, and an 11.9% larger turning angle compared to the 3D simulation. This discrepancy is primarily due to the 2D model's inability to accurately represent the fish body's mass distribution and force characteristics, resulting in artificially elevated performance. Nevertheless, 2D simulations remain applicable for studying the propulsion performance of fish with elongated cross-sections and large fin areas. Comparison between the simulated and real motion performance reveals that, under the self-propelled computational model, both 2D and 3D numerical simulations consistently capture the qualitative motion patterns. The quantitative results also reflect the actual swimming performance of the fish within an acceptable margin of error. [ABSTRACT FROM AUTHOR]

Both flexoelectric effect and dielectric effect affect the director of uniform lying helix (ULH) cholesteric liquid crystals (CLCs). By using a finite-difference iterative method to solve the numerical solution of the Euler equations, we investigate the polar angle and the tilt angle of the director affected by the coupling of flexoelectric effect and dielectric effect. We find that flexoelectric effect and dielectric effect can be quantitatively analysed, and dielectric effect makes the director changes nonuniformly in the helix plane and inclines unevenly with respect to the helix plane. We conclude that the tilt angle is not affected by the dielectric effect under one-constant approximation. In nonequal elastic constants, the influence of dielectric effect on tilt angle is different. Under the same electric field and dielectric anisotropy, the decrease of K33 or K22 can increase the title angle, and K33 has more influence on the title angle than K22. Remarkably, our method provides a more accurate theory basis for the rotation of the optic axis in ULH CLCs. [ABSTRACT FROM AUTHOR]

In a cylindrical cavity with a degenerate planar anchoring, the lyotropic chromonic nematic liquid crystals without intrinsic chirality tend to exhibit an escaped twisted configuration for the large saddle-splay-to-twist elastic modulus ratio, which is not found in most thermotropic liquid crystals. In this work, we consider thermotropic nematic liquid crystal 5CB with a chiral dopant confined in a cylindrical cavity with a degenerate planar anchoring. Based on the elastic theory of liquid crystal and the variation method, Euler equation and boundary conditions are obtained. The numerical results show that the director of 5CB forms an escaped twisted configuration, and the twist angle is influenced by the chiral parameter and the saddle-splay elastic constant. Under an axial electric field, the dielectric effect and the flexoelectric effect affect the LC director distribution. The single flexoelectric coefficient e1 has a large radial orientation effect on the director. The results provide a clearer understanding of the director configuration in the cylindrical cavity under the electric field and a theoretical basis for the measurement of the flexoelectric coefficients. [ABSTRACT FROM AUTHOR]

A striking feature of lyotropic chromonic liquid crystals confined in cylinder model exhibit double-twist director configurations. Evidence suggests that saddle-splay deformation is among the most important factors for the distortions of director. Previous researches limit the director to distort at a fixed plane (r-ϕ plane) by using specific boundary conditions such as degenerate planar anchoring condition. In this work, we consider lyotropic chromonic liquid crystals confined between two coaxial cylinders with free-surface boundary conditions and Rapini-Papoular-type anchoring conditions. By using finite-difference iterative method to solve the numerical solution of Euler equation, we find that saddle-splay deformation leads to double-twist director configurations under free-surface boundary conditions, which consist of the result under degenerate planar anchoring conditions. Furthermore, at Rapini-Papoular-type anchoring conditions, saddle-splay deformation has a great influence on the director in the radial direction (r direction) and the director distorts in three-dimensional space. Remarkably, our method provides a more accurate theory basis for the measured values of saddle-splay elastic constant K24。 [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H 2 S) has comprehensive contributions to maintaining the normal operation and stability of organisms, and it also occurs in the wastewater environment and is related to the deterioration of foodstuffs. Therefore, developing high-sensitive detection techniques for tracing H 2 S is promising and meaningful. Inspired by this, a novel nopinone-based fluorescent probe NPS for the recognition of H 2 S was designed and synthesized with excellent sensitivity, low limit of detection (79 nM), good selectivity, and wide pH range (5-9). NPS could emit strong yellow fluorescence and its emission intensity showed a remarkable augmentation at 520 nm upon the supplement of H 2 S. Furthermore, the recognition mechanism of NPS for H 2 S was verified by the HRMS analysis, 1 H NMR spectra titration, and DFT computation. What is more, NPS also had broad applications in the monitoring of real water samples, red wine, beer, and eggs samples, which showed its development prospect and value in environmental pollution, foodstuffs quality analysis fields. NPS also was applied to monitor trace exogenous H 2 S and bioimaging in living cells and zebrafish.