Although the effective “stealth” of space vehicles is important, current camouflage designs are inadequate in meeting all application requirements. Here, a multilayer wavelength-selective emitter is demonstrated. It can realize visible light and dual-band mid-infrared camouflage with thermal control management in two application scenarios, with better effect and stronger radiation cooling capability, which can significantly improve the stealth and survivability of space vehicles in different environments. The selective emitter demonstrated in this paper has the advantages of simple structure, scalability, and ease of large-area fabrication, and has made a major breakthrough in driving multiband stealth technology from simulation research to physical verification and even practical application.
Space vehicles need to be able to hide themselves effectively in some specific scenarios; however, existing camouflage designs do not fully realize the "stealth" of a variety of existing detectors, and a large distance is required to meet the needs of all-round applications. We propose a \(\text{G}\text{e}/\text{Y}\text{b}{\text{F}}_{3}\) multilayer wavelength-selective emitter that covers more wavelengths with better camouflage effect and radiation cooling than previous developments. In addition, our emitter substantially reduces the implementation difficulty and cost of detection instruments while greatly improving the stealth effect and survivability of space vehicles in different environments. Simulations and experiments are used to demonstrate that the emitter performs visible and dual-band mid-infrared camouflage with thermal control management in two different application scenarios. First, the application to aircraft skin enables simultaneous infrared camouflage in two bands (low emissivity in atmospheric windows, \({\stackrel{-}{\epsilon }}_{3-5\mu m}=0.06\) and \({\stackrel{-}{\epsilon }}_{8-14\mu m}=0.01\)) and radiative cooling (high emissivity in non-atmospheric window, \({\stackrel{-}{\epsilon }}_{5-8\mu m}=0.68\)) as well as visual camouflage (low average reflectance of 0.21 in visible band). This selective infrared emission characteristic is preserved for incidence angles of radiated light ranging from 0° to 60°. Second, we combine the wavelength-selective emitter with insulating silica aerogel for application to the converging nozzle of aircraft, obtaining a reduction in the apparent temperature of the object from 873 K to approximately 313 K in detection ranges of 3–5 and 8–14 µm with and without earthshine. This in turn reduces the target detectable lock-on range by approximately 79% and provides an excellent infrared stealth effect. Moreover, the emitter has a simple structure and scalability, and provides convenience for mass production.
Bolbostemma paniculatum (Maxim.) Franquet is a unique species in China with a long history of medicinal use, which has the effects of detoxifying, dissolving lumps and dispersing swellings. And it is commonly used to treat many diseases, such as carbuncle and sore, acute mastitis, mammary cancer, scrofula and subcutaneous nodule traditionally. Modern clinical studies have found that B. paniculatum and its compounds can be used for the treatment of a variety of cancers, mastitis, hyperplasia of mammary glands, chronic lymphadenitis, cervical lymph tuberculosis and surgical wart skin diseases, and the curative effect is positive. At present, a variety of Chinese patent medicines containing B. paniculatum have been exploited and marketed in China for the treatment of cancers, breast diseases and flat warts. This review article comprehensively discussed the traditional application, botany, chemical components, pharmacological activities, and quality control of B. paniculatum, put forward some noteworthy issues and suggestions in current studies, and briefly discussed the possible development potential of this plant as well as future research perspectives. 96 compounds have been isolated from B. paniculatum, including triterpenoids, sterols, alkaloids and other components, of which triterpenoid saponins are the main bioactive components. The crude extracts and monomer compounds of B. paniculatum have a wide range of pharmacological activities, such as anti-tumor, antiviral, anti-inflammatory, immunoregulatory, and so on. Moreover, its anti-tumor mechanism involves many aspects, including inhibiting cell proliferation, promoting cell apoptosis, blocking the cell cycle, interfering with cell invasion and metastasis, suppressing angiogenesis, and regulating autophagy. While there is a lack of systematic and in-depth research on its anti-tumor active components and mechanism of action at the moment; and a tight connection between the chemical composition and pharmacological activity of B. paniculatum has also not been established. Besides, a systematic quality determination standard for B. paniculatum should also be built, in order to carry out further research.
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