Fluid-Solid Interfacial Properties and Drag-Reducing Characterization of the Flexible Conical Microstructured Film Inspired by the Streamlined Body Surface of the Pufferfish.

Given the challenges in accurately replicating the surface of the pufferfish, this study employed three-dimensional (3D) printing to create a model based on inverse modeling. The morphology of the pufferfish exhibits a streamlined configuration, characterized by a gradual widening from the anterior oral region to the central ocular area, followed by a progressive narrowing from the midabdominal region toward the caudal extremity. The RNG k-ε turbulence simulation results demonstrate that the streamlined body surface of the pufferfish diminishes differential pressure resistance. This enhancement promotes laminar flow formation, delays fluid separation, minimizes turbulence-induced vortices, and reduces frictional resistance. Moreover, the pufferfish's supple and uneven outer epidermis was simplified into a flexible, nonsmooth planar film to conduct fluid-solid coupling simulations. These revealed that the pufferfish's unique skin can absorb turbulent energy and minimize momentum transfer between the fluid and the solid film, lowering the fluid resistance during swimming. In summary, The high-efficiency swimming capacity of pufferfish stems not only from their streamlined body surface but also significantly from the unique structural characteristics and mechanical properties of their flexible skin. This research provides critical theoretical underpinnings for the design of functional bionic surfaces aimed at drag reduction.

Superhydrophobic Surfaces with Excellent Ice Prevention and Drag Reduction Properties Inspired by Iridaceae Leaf.

The anti-icing and drag-reduction properties of diverse microstructured surfaces have undergone extensive study over the past decade. Nonetheless, tough environments enforce stringent demands on the composite characteristics of superhydrophobic surfaces (SHS). In this study, fresh composite structures were fabricated on a metal substrate by nanosecond laser machining technology, drawing inspiration from the hardy plant Iridaceae. The prepared sample surface mainly consists of a periodic microrhombus array and irregular nanosheets. To comprehensively investigate the effect of its special structure on surface properties, three surfaces with different sizes of rhombic structures were used for comparative analysis, and the results show that the SH-S2 sample is optimal. This can significantly delay the freezing time by an impressive 1404 s at -10 °C while revealing the sample surface anti-icing strategy. In addition, the rheological experiments determined over 300 µm of slip length for the SH-S2 sample, and the drag reduction rate of the surface reaches nearly 40%, which is well aligned with the results of the delayed icing experiments. Finally, the mechanical durability of the SH-S2 surface was investigated through scratch damage, sandpaper abrasion, reparability trials, and icing and melting cycle tests. This research presents a new approach and methodology for the application of SHS on polar ship surfaces.

Risk Factors for Left Ventricular Hypertrophy in Patients with Diabetic Kidney Disease: A Multi-Center Study.

Objective: One of the earliest echocardiographic features of the left ventricle explored extensively was left ventricular hypertrophy (LVH). Numerous studies have identified a few risk factors for LVH, however, there are few for people with diabetic kidney disease (DKD). Therefore, we evaluated the risk factors in DKD patients with LVH by analyzing laboratory data and clinical traits. Methods: In total, 500 DKD patients in the Baoding area from February 2016 and June 2020 were admitted and classified as an experimental group (240 cases, LVH group) and a control group (260 cases, non-LVH group). The clinical parameters and laboratory tests of the participants were collected and analyzed retrospectively. Results: Compared with the control group, low-density lipoprotein (LDL), body mass index (BMI), intact parathyroid hormone (iPTH), systolic blood pressure, and 24-hour urine protein were higher in the experimental group (all P<0.01). Multivariable logistic regression analysis results confirmed that high BMI (OR=1.332, 95% CI 1.016-1.537, P=0.006), LDL (OR=1.279, 95% CI 1.008-1.369, P=0.014) and 24-hour urine proteins (OR=1.446, 95% CI 1.104-1.643, P=0.016) were statistically significant. The ROC analysis illustrated that the optimum cutoff value of BMI, LDL, and 24-hour urine proteins for diagnosis of LVH in patients with DKD was 27.36 kg/m2, 4.18 mmol/L, and 1.42 g respectively. Conclusion: The increase in BMI, LDL, and 24-hour urine proteins quantification are independent risk factors for LVH in patients with DKD.

Synthesis and nonlinear optical properties in the near-IR range of stilbazolium dyes.

A series of stilbazolium salts based on donor-π-acceptor (D-π-A) structure have been synthesized and fully characterized. Photophysical properties including linear absorption, one-photon excited fluorescence (OPEF), two-photon absorption (2PA) properties were systematically investigated. The results suggest that increasing electron-releasing character of the terminal group leads to a more pronounced donor-to-acceptor intramolecular charge transfer (ICT). In addition, the dyes possess the largest 2PA cross sections in the near infrared region (NIR) and display maximum two-photon absorption cross sections within the narrow wavelength range from 950 to 970nm and BL3 exhibits a large nonlinear refractive index coefficient and possesses very large values of the real part of the cubic hyperpolarizability χ((3)) at 960nm. Furthermore, the initial density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations provide reasonable explanations for their absorption spectra, meanwhile we used the Lippert-Mataga equation to evaluate the dipole moment changes of the dyes with photoexcitation, the results are corresponding with linear and nonlinear optical properties of the dyes.