Search

The pectoral fin propulsion of a bionic robotic fish always consists of two phases: propulsion and recovery. The robotic fish moves in a burst-and-coast swimming manner. This study aims to analyze a pair of bionic robotic fish with rigid pectoral fin propulsion with three degrees of freedom and optimize the elliptical propulsion curve with the minimum recovery stroke resistance using computational fluid dynamics methods. Then, the time allocated to the propulsion and recovery phases is investigated to maximize the propulsion performance of the bionic robotic fish. The numerical simulation results show that when the time ratio of the propulsion and recovery phases is 0.5:1, the resistance during the movement of the robotic fish is effectively reduced, and the drag-reducing effect is pronounced. According to a further analysis of pressure clouds and vortex structures, the pressure difference between the upstream and downstream fins of the pectoral fin varies with different stroke ratios. The increase in recovery phase time helps to prevent premature damage to the vortex ring structure generated during the propulsion process and improves propulsion efficiency. [ABSTRACT FROM AUTHOR]

Ion evaporation from charged surfaces of ionic liquids has aroused significant interest due to its wide range of applications in various fields, such as ionic liquid ion sources (ILIS), electrospray thrusters, and high-precision etching, among others. This study delves into the transient electrohydrodynamics of ionic liquid drops undergoing ion evaporation with the assistance of an externally applied electric field. A transient electrohydrodynamic (EHD) model is developed to make up for the dearth of direct observation (visualization). A structure morphologically resembling the traditional cone-jet is depicted, featuring charged jets emitted from the drop's ends that subsequently break into tiny droplets. In contrast to the traditional cone-jet, this structure forms through a distinct mechanism, with charge depletion induced by ion evaporation playing a crucial role. A comprehensive exploration of parameter influences reveals the following key findings: (a) the normalized radius of the jets increases with the augmentation of the dimensionless number Ξ, which is defined as the ratio of the electric potential energy of ions to their activation energy for evaporation; (b) enhancing the electric Bond number Bo, which quantifies the ratio of Maxwell stress to surface tension, expedites the temporal evolution of tip streaming. [ABSTRACT FROM AUTHOR]

Laportea bulbifera (Sieb. et Zucc.) Wedd. (L. bulbifera) is a significant plant in the Laportea genus. Traditionally, it has been used in ethnomedicine for treating various conditions such as rheumatic arthralgia, fractures, falling injuries, nephritis dropsy, limb numbness, pruritus, fatigue-induced internal imbalances, and irregular menstruation. Modern pharmacological studies have confirmed its therapeutic potential, including anti-inflammatory, immunosuppressive, analgesic, and anti-rheumatoid arthritis properties. To gather comprehensive information on L. bulbifera, a thorough literature search was conducted using databases like Web of Science, PubMed, ProQuest, and CNKI. This review aims to provide a comprehensive understanding of L. bulbifera, covering various aspects such as ethnomedicinal uses, geographical distribution, botanical description, phytochemistry, pharmacology, and quality control. The goal is to establish a solid foundation and propose new research avenues for exploring and developing potential applications of L. bulbifera. So far, a total of one hundred and eighty-nine compounds have been isolated and identified from L. bulbifera, including flavonoids, phenolics, nitrogen compounds, steroids, terpenoids, coumarins, phenylpropanoids, fatty acids and their derivatives, and other compounds. Notably, flavonoids and fatty acids have demonstrated remarkable antioxidant and anti-inflammatory properties. Additionally, these compounds show promising potential in activities such as analgesia, hypoglycemia, and hypolipidemia, as well as toxicity. Despite extensive fundamental studies on L. bulbifera, further research is still needed to enhance our understanding of its mechanism of action and improve quality control. This requires more comprehensive investigations to explore the specific material basis, uncover new mechanisms of action, and refine quality control methods related to L. bulbifera. By doing so, we could contribute to the further development and utilization of this plant. [ABSTRACT FROM AUTHOR]

Swertia perennis Linnaeus (SP) has been utilised to treat gastritis. We report the qualitative and quantitative phytochemical analysis, antioxidant and enzyme inhibitory activities of SP. The correlation between the biological activities and total bioactive contents of the extracts was also studied via multivariate analysis. Methanol extract contained many active compounds and exhibited good antioxidant activity. Therefore, this was selected for further phytochemical profiling and stability studies. Fourteen compounds were identified by ultra-performance liquid chromatography-electrospray ionisation-orbitrap-mass spectrometry for the first time from this plant. Iridoids, xanthones, and flavonoids were the main components. Methanol extract exhibited good stability and antioxidant capacity in stability studies, with low toxicity, and showed a protective effect on the oxidation of olive and sunflower oils. SP has the potential to be developed and used as an antioxidant, or as urease and XO inhibitors, and its methanol extract could be used as a natural oil stabiliser. [ABSTRACT FROM AUTHOR]

This study investigated the content and biological activity of three solvent extracts of Adonis ramosa Franch (AR), which contains 12 types of phytochemicals. The overall yield and total protein content of the aqueous extract were the highest, and it exhibited the highest hydroxyl and superoxide radical-scavenging abilities, copper chelating abilities, and cupric reducing antioxidant capacity. Ethanol extract had the highest total phenolic, flavonoid, and carbohydrate contents, and it showed the highest iron chelating activity, and HClO- and nitrite-scavenging abilities. Methanol AR extract contained the highest total steroid and tannin contents; it also demonstrated high radical- and reactive oxygen species-scavenging abilities and had the best ferric reducing antioxidant power, which allowed it to effectively prevent β-carotene bleaching. Methanol extract also showed good stability and low toxicity. All tested solvent extracts of AR exhibited weak enzyme-inhibitory activities for four enzymes (α-glucosidase, α-amylase, acetylcholinesterase and butyrylcholinesterase). Overall, AR can serve as a natural antioxidant. [ABSTRACT FROM AUTHOR]