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ABSTRACTElastomers are widely used in electronics and electrical devices, either as insulators or transducers. The insulation and actuation performance of elastomers are highly susceptible to their dielectric strength. Among the factors that influence the dielectric strength of elastomers, material viscoelasticity is an important factor that needs further investigation. Since the material viscoelasticity is often characterized by rate-dependent behaviors, we present two different sample configurations to experimentally examine the electrical and mechanical rate dependence of the dielectric strength of VHB 4905 elastomers. At pre-stretch ratio of 4, the improvement of the dielectric strength is about 30% from voltage ramp of 50 V/s to 800 V/s. Particularly, with an in-house biaxial test platform, the effect of the stretching rate on the dielectric strength is examined for the first time. The improvement of the dielectric strength is about 35% from stretching rate of 0.1 mm/s to 5 mm/s. Moreover, a dielectric strength predictor based on configurational stress is adopted to describe the experimental data. According to the predictor, the loading rate affects the dielectric strength of the elastomer mainly by influencing the evolution of the inelastic deformation.

The present investigations on tandem wing configurations primarily revolve around the effects of the spacing L and the phase difference φ between the forewing and the hindwing on aerodynamic performance. However, in nature, organisms employing biplane flight, such as dragonflies, demonstrate the ability to achieve superior aerodynamic performance by flexibly adjusting their flapping trajectories. Therefore, this study focuses on the effects of φ, as well as the trajectory of the hindwing, on aerodynamic performance. By summarizing four patterns of wake–wing interaction processes, it is indicated that φ=−90∘ and 0∘ enhances the thrust of the hindwing, while φ=90∘ and 180∘ result in reductions. Furthermore, the wake–wing interactions and shedding modes are summarized corresponding to three kinds of trajectories, including elliptical trajectories, figure-eight trajectories, and double figure-eight trajectories. The results show that the aerodynamic performance of the elliptical trajectory is similar to that of the straight trajectory, while the figure-eight trajectory with positive surging motion significantly enhances the aerodynamic performance of the hindwing. Conversely, the double-figure-eight trajectory degrades the aerodynamic performance of the hindwing.

It is still a serious public health issue that chronic kidney disease of uncertain etiology (CKDu) in Sri Lanka poses challenges in identification, prevention, and treatment. What environmental factors in drinking water cause kidney damage remains unclear. This study aimed to investigate the risks of various environmental factors that may induce CKDu, including water hardness, fluoride (HF), heavy metals (HM), microcystin-LR (MC-LR), and their combined exposure (HFMM). The research focused on comprehensive metabolome analysis, and correlation with transcriptomic and gut microbiota changes. Results revealed that chronic exposure led to kidney damage and pancreatic toxicity in adult zebrafish. Metabolomics profiling showed significant alterations in biochemical processes, with enriched metabolic pathways of oxidative phosphorylation, folate biosynthesis, arachidonic acid metabolism, FoxO signaling pathway, lysosome, pyruvate metabolism, and purine metabolism. The network analysis revealed significant changes in metabolites associated with renal function and diseases, including 20-Hydroxy-LTE4, PS(18:0/22:2(13Z,16Z)), Neuromedin N, 20-Oxo-Leukotriene E4, and phenol sulfate, which are involved in the fatty acyls and glycerophospholipids class. These metabolites were closely associated with the disrupted gut bacteria of g_ZOR0006, g_Pseudomonas, g_Tsukamurella, g_Cetobacterium, g_Flavobacterium, which belonged to dominant phyla of Firmicutes and Proteobacteria, etc., and differentially expressed genes (DEGs) such as egln3, ca2, jun, slc2a1b, and gls2b in zebrafish. Exploratory omics analyses revealed the shared significantly changed pathways in transcriptome and metabolome like calcium signaling and necroptosis, suggesting potential biomarkers for assessing kidney disease.

The development of simple and accurate detection of uracil-DNA glycosylase (UDG) is of great significance for early clinical diagnosis and biomedical research. Here, we on the first effort introduced the uracil bases into the rolling circle amplification (RCA) reaction to produce the functionalized pure DNA hydrogel (PDH) for UDG detection. During RCA process, methylene blue (MB) molecules as the indicators were encapsulated into PDH. The addition of UDG can remove the uracil bases of PDH to generate abasic sites, which are further cleaved with the assistance of apurinic/apyrimidinic endonuclease (APE), thus resulting in the dissociation of PDH to release blue MB. By combining with the paper analytical devices as the signal readout platform, a colorimetric and electrochemical dual-signal biosensor was constructed for convenient and accurate detection of UDG. The proposed MB@PDH-based dual-signal sensing system exhibited good selectivity and high sensitivity with a detection limit of 6.4 × 10−4 U/mL (electrochemical method). It was also demonstrated that this sensing system showed excellent performance in UDG inhibitor screening, thus providing great potential in UDG-related disease diagnosis and drug discovery.

Elastomers are commonly used as insulators or actuators in important fields such as robotics and electronics. The performance of elastomers is strongly influenced by their dielectric permittivity while determining the dielectric permittivity of elastomers appears to be rather challenging. With image processing techniques and a motor-driven biaxial test setup, the dynamic variation of the dielectric permittivity and dielectric loss of elastomers under dynamic mechanical constraints is first examined in this paper. Also, the mechanical rate-dependence and the cyclic behavior of the dielectric permittivity are investigated. At a given mechanical loading rate, the change in the dielectric permittivity is found to follow a cubic polynomial function. The variations of the stress and the dielectric permittivity indicate the mechanical constraints on the polarization of the material. Our experiment setup allows different mechanical loading paths to be applied to the elastomer when simultaneously measuring the dielectric permittivity and the dielectric loss.