Multilayered structure at the macroscale is a prevailing pathway for developing high-performance energy absorbers. Nowadays, most multilayer-structure-based energy absorbers are constructed with rigid materials, but research on utilizing soft materials as energy-absorbing devices is still rare. By understanding the function of membranous sheathes in the stimuli responsiveness of fan worms (Polychaeta: Sabellastarte australiensis), in this work, we report a robust biological energy absorber made of multilayer-structured soft material. Our study reveals that structural features govern the mechanical performance and the energy-absorption capacity of this soft energy absorber. Ultimately, through kinematic analysis of fan worms, we elucidate the advantage of soft-material-based energy absorbers in stabilizing assistance compared with rigid counterparts. Our work takes a significant step toward understanding the design principle of soft-material-based energy absorbers and may shed light on flexible protective devices for soft robotics.
Abstract Objective Diagnosing acute pulmonary embolism (PE) is challenging because of nonspecific clinical symptoms. Soluble lectin-type oxidized low-density lipoprotein receptor (sLOX-1) has differential expression in arterial and venous disease. This study aimed to evaluate the relevance of soluble lectin-type oxidized low-density lipoprotein receptor (sLOX-1) as a diagnostic biomarker for acute PE. Methods This observational study was performed at Beijing Anzhen Hospital in China. Patients with PE, aortic dissection (AD), myocardial infarction (MI) and healthy controls were enrolled in this cross-sectional study (n=90 each). Moreover, 730 patients with suspected PE were enrolled in this prospective study. The diagnostic performance of sLOX-1 was assessed using the receiver operating characteristic curve analysis. Results In the development set, sLOX-1 levels were significantly lower in patients with PE than in those with AD, MI, or healthy controls. In the validation cohort, the area under the curve (AUC) of sLOX-1 for patients with PE from other chest pain diseases, particularly from AD was significantly higher than that of D-dimer (ΔAUC=0.32; 95%CI, 0.26-0.37; P<0.0001) with 77.0% specificity and 74.5% positive predictive value at the threshold of 600 pg/mL derived from the development set. By integrating sLOX-1 into existing diagnosis strategy (Wells rules combined D-dimer), the number of patients who were further categorized as workup for PE decreased from 417 to 209, with the positive detection rate of computed tomographic pulmonary angiography increased from 35.1% to 67.0%. Six patients with PE were missed in 208 excluded patients at a failure rate of 2.88%. Conclusions Plasma sLOX-1 is a novel diagnostic tool that can rapidly categorize suspected PE as a workup for PE based on existing diagnostic strategy.
A bee's tongue is coated in dynamic hairs that gradually unfold to entrain the viscid nectar, during which hairs inevitably deflect as a result of fluid drag. The hair deflection induced decline in nectar capture rate may be a coupled elastoviscous problem and remains poorly understood. Here we employed geometric beam theory coupled with the effective viscous force to derive a dynamic model for a rotary tongue hair deflection in a viscous fluid. Considering deflection of the tongue hair, we rationalized the nectar capture rate by takingBombusterrestrisas a model system. When the nectar concentration increases from 20% to 70%, the nectar capture rate declines by 87%, indicating that hair erection is more severely impeded in thicker nectar. Based on this model, we predicted an optimal hair length with which the bee can reach the maximum nectar capture rate. This work may provide a new theoretical framework for quantifying viscous liquid transport by hairy surfaces and shed light on design methodologies for fluid transport devices using hairy beds.
Bioinspired Continuum Robots In article number 2201616, Ji Liu, Haijun Peng, Jianing Wu, and co-workers present a three-segment continuum robot constructed by a class-3 tensegrity structure, inspired by the mechanism of an elephant trunk for regulating local stiffness. It relies on a stiffness tunable material to achieve the robotic stiffness programmable characteristics. This study may provide a foundation for the potential application of continuum robots for interacting with unstructured environments.
Fibrous surfaces in nature have already exhibited excellent functions that are normally ascribed to the synergistic effects of special structures and material properties. The honey bee tongue, foraging liquid food in nature, has a unique segmented surface covered with dense hairs. Since honey bees are capable of using their tongue to adapt to possibly the broadest range of feeding environments to exploit every possible source of liquids, the surface properties of the tongue, especially the covering hairs, would likely represent an evolutionary optimization. In this paper, we show that their tongue hairs are stiff and hydrophobic, the latter of which is highly unexpected as the structure is designed for liquid capturing. We found that such hydrophobicity can prevent those stiff hairs from being adhered to the soft tongue surface, which could significantly enhance the deformability of the tongue when honey bees feed at various surfaces and promote their adaptability to different environments. These findings bridge the relationship between surface wettability and structural characteristics, which may shed new light on designing flexible microstructured fiber systems to transport viscous liquids.
The present study focuses on the investigation of owl-inspired propellers featuring a variety of serrated trailing edge configurations. A comprehensive analysis is conducted using a numerical model that combines computational fluid dynamics (CFD) with the incorporation of Large Eddy Simulation (LES) and Lighthill acoustic analogy. Simulation endeavors to elucidate the underlying mechanism responsible for the noise reduction achieved by the bionic propeller through a comparative examination of propeller tip vortices and wake region vortices with or without serrated trailing edge structures. Furthermore, a comprehensive assessment of noise and aerodynamic performance is conducted on bionic propellers featuring diverse serrated ratios, shapes, and coverage degrees, through rigorous experimental measurements conducted under varying rotation speeds and thrust levels. Experimental demonstrated the significant noise reduction capabilities of sawtooth bionic structures across a broad range of rotation speeds. Notably, the bionic propeller featuring a round-serrated trailing edge, a serrated ratio of 0.9, an arc radius of 0.3mm, and serration coverage spanning 50% of the propeller span attains an impressive noise reduction of up to 4.4 dBA. The findings underscore a compelling correlation between the propeller's flow structure and its aerodynamic noise characteristics. Serrated trailing edges effectively disrupt propeller tip vortices, subsequently expediting the vortex shedding and dissipation processes, thereby mitigating trailing edge noise. Additionally, a distinctive inward shift of the wake at the trailing edge promotes the intermixing of flow structures, resulting in enhanced collisions and mixing of vortices, ultimately leading to a significant broadband noise reduction.
Glioma is the most common primary brain tumor in the central nervous system (CNS) with high morbidity and mortality in adults. Although standardized comprehensive therapy has been adapted, the prognosis of glioma patients is still frustrating and thus novel therapeutic strategies are urgently in need. Quercetin (Quer), an important flavonoid compound found in many herbs, is shown to be effective in some tumor models including glioma. Recently, it is reported that adequate regulation of autophagy can strengthen cytotoxic effect of anticancer drugs. However, it is not yet fully clear how we should modulate autophagy to achieve a satisfactory therapeutic effect. 3-Methyladenine (3-MA) and Beclin1 short hairpin RNA (shRNA) were used to inhibit the early stage of autophage while chloroquine (CQ) to inhibit the late stage. MTT assay was implemented to determine cell viability. Transmission electron microscopy, western blot, and immunohistochemistry were adopted to evaluate autophagy. Western blot, flow cytometry, and immunohistochemistry were used to detect apoptosis. C6 glioma xenograft models were established to assess the therapeutic effect (the body weight change, the median survival time, and tumor volume) in vivo. Quercetin can inhibit cell viability and induce autophagy of U87 and U251 glioma cells in a dose-dependent manner. Inhibition of early-stage autophagy by 3-MA or shRNA against Beclin1 attenuated the quercetin-induced cytotoxicity. In contrast, suppression of autophagy at a late stage by CQ enhanced the anti-glioma efficiency of quercetin. Therapeutic effect of quercetin for malignant glioma can be strengthened by inhibition of autophagy at a late stage, not initial stage, which may provide a novel opportunity for glioma therapy.
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