5 research outputs found
Multifunction full space graphene assisted metasurface
In recent years, there has been notable advancement in programmable
metasurfaces, primarily attributed to their cost-effectiveness and capacity to
manipulate electromagnetic (EM) waves. Nevertheless, a significant limitation
of numerous available metasurfaces is their capability to influence wavefronts
only in reflection mode or transmission mode, thus catering to only half of the
spatial coverage. To the best of our knowledge and for the first time, a novel
graphene-assisted reprogrammable metasurface that offers the unprecedented
capability to independently and concurrently manipulate EM waves within both
half-spaces has been introduced in the THz frequency band
Reprogrammable reflection-transmission integrated coding metasurface for real-time terahertz wavefront manipulations in full-space
Abstract In recent years, there has been notable advancement in programmable metasurfaces, primarily attributed to their cost-effectiveness and capacity to manipulate electromagnetic (EM) waves. Nevertheless, a significant limitation of numerous available metasurfaces is their capability to influence wavefronts only in reflection mode or transmission mode, thus catering to only half of the spatial coverage. To the best of our knowledge and for the first time, a novel graphene-assisted reprogrammable metasurface that offers the unprecedented capability to independently and concurrently manipulate EM waves within both half-spaces has been introduced in the THz frequency band. This intelligent programmable metasurface achieves wavefront control in reflection mode, transmission mode, and the concurrent reflection-transmission mode, all within the same polarization and frequency channel. The meta-atom is constructed with two graphene sections, enabling straightforward modification of wave behavior by adjusting the chemical potential distribution within each graphene segment via an external electronic source. The proposed functionalities encompass various programmable modes, including single and dual beam control in reflection mode, dual beam control in transmission mode, simultaneous control of dual beams in reflection mode-direct transmission, and vice versa, and control of beam steering in reflection mode-dual beams in transmission mode simultaneously. The proposed metasurface is expected to be reprogrammable due to wavefront manipulation in both half-spaces separately and continuously for various applications such as imaging systems, encryption, miniaturized systems, and next-generation wireless intelligent communications
Multi-channel polarization manipulation based on graphene for encryption communication
Abstract Wave-based cryptography, at the vanguard of advancing technologies in advanced information science, is essential for establishing a diverse array of secure cryptographic platforms. The realization of these platforms hinges on the intelligent application of multiplexing techniques, seamlessly combined with appropriate metasurface technology. Nevertheless, existing multi-channel encryption technologies based on metasurfaces face challenges related to information leakage during partial channel decoding processes. In this paper, we present a reprogrammable metasurface for polarization modulation. This metasurface not only allows for the arbitrary customization of linearly polarized reflected waves but also enables real-time amplitude modulation. Here, relying on polarization amplitude control, a fully secure communication protocol is developed precisely in the terahertz (THz) spectrum to achieve real-time information encryption based on polarization modulation metasurfaces where access to information is highly restricted. The proposed metasurface employs the double random phase encryption (DRPE) algorithm for information encryption. It transmits the encrypted data through different polarization channels using two graphene nanoribbons, exclusively controlled by external biasing conditions. Various encryption scenarios have been outlined to fortify information protection against potential eavesdroppers. The simulated results show that this unique technology for hiding images by manipulating the polarization of the reflected wave provides new opportunities for various applications, including encryption, THz communications, THz secure data storage, and imaging
Evaluating the effects of air disinfectants in decontamination of COVIDâ19 aerosols
Abstract Introduction Airborne transmission is the most âŻcrucial mode of COVIDâ19 transmission. Therefore, disinfecting the severe acute respiratory syndrome coronavirusâ2 (SARSâCoVâ2) aerosols float can have important implications in limiting COVIDâ19 transmission. Herein, we aimed to review the studies that utilized various disinfectants to decontaminate and inactivate the SARSâCoVâ2 aerosols. Methods This study was a review that studied related articles published between December 1, 2019 and August 23, 2022. We searched the online databases of PubMed, Scopus, Web of Science, Cochrane, on August 23, 2021. The studies were downloaded into the EndNote software, duplicates were removed, and then the studies were screened based on the inclusion/exclusion criteria. The screening process involved two steps; first, the studies were screened based on their title and abstract and then their full texts. The included studies were used for the qualitative analysis. Results From 664 retrieved records, only 31 met the inclusion criteria and were included in the final qualitative analysis. Various materials like Ozone, H2O2, alcohol, and TiO2 and methods like heating and using Ultraviolet were described in these studies to disinfect places contaminated by COVIDâ19. It appeared that the efficacy of these disinfectants varies considerably depending on the situation, time, and ultimately their mode of application. Conclusion Following reliable protocols in combination with the proper selection of disinfectant agents for each purpose would serve to achieve desired elimination of the SARSâCoVâ2 transmission
Impact of COVID â19 pandemic on routine vaccination coverage of children and adolescents: A systematic review
International audienceScientists and healthcare workers have expressed their concerns on the impacts of the COVID-19 pandemic on vaccination coverage in children and adolescents. Therefore, we aimed to systematically review the studies addressing this issue worldwide