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Background: Inadequate supply of filtering facepiece respirators (FFR) for healthcare workers during a global pandemic such as the novel coronavirus outbreak (SARS-CoV-2) is a serious public health issue. Aim: The objective of this review was to synthesize existing data on the effectiveness of ultraviolet germicidal irradiation (UVGI) on N95 FFR decontamination. Methods: We conducted a systematic review on UVGI in N95 FFRs by using Embase, Medline, Global Health, Google Scholar, WHO feed, and MedRxiv. Two reviewers independently determined study eligibility and extracted and verified predefined data fields. Original research reporting on N95 FFR function, decontamination, or mask fit following UVGI were included. Findings and Conclusions: Twelve studies were identified, comprising of 53 different UVGI intervention arms and 43 N95 FFR models. In all cases, FFRs maintained National Institute for Occupational Safety and Health (NIOSH) certification standards following UVGI. Aerosol penetration averaged 1.19% (0.70-2.48%) and 1.14% (0.57-2.63%) for control and UVGI arms respectively. Airflow resistance for the control arms averaged 9.79 mm H2O (7.97-11.70 mm H2O) vs 9.85 mm H2O (8.33-11.44 mm H2O) for UVGI treatment arms. All UVGI protocols employing a cumulative dose >20,000 J/m2 resulted in a 2 log reduction in viral load. A >3 log reduction was observed in 7 UVIG arms using a dose >40,000 J/m2. Impact of UVIG on fit was evaluated in two studies (16,200; 32,400 J/m2) and did not find evidence of compromise. Altogether, our findings suggest that further work in this area should use a cumulative UV-C dose of 40,000 J/m2 or greater, and confirm appropriate mask fit following decontamination.

Background: In pandemic situations such as COVID-19, shortages of proper protective equipment are common. One solution may be to decontaminate equipment such as facemasks for reuse.Aim: The aim of this review was to collect and synthesize existing information on decontamination of N95 filtering facepiece respirators (FFRs) using microwave and heat-based treatments, with special attention to impact on mask function (aerosol penetration, airflow resistance) and fit.Methods: A systematic review (PROSPERO ID pending) of literature available on Medline, Embase, Global Health, JISRP and JEFF was conducted. Records were screened independently by two reviewers, and data was extracted and analyzed from studies that reported on the effects of microwave- or heat-based decontamination on N95 FFR performance and/or microbial load. Results: All interventions successfully destroyed viral/bacterial contaminants. Other than autoclaving, which significantly increased aerosol penetration, moist and dry microwave and heat conditions did not significantly impact functional parameters or fit. However, several conditions caused physical damage to at least one N95 model. Conclusions: Microwave irradiation and heat provides safe and effective decontamination options for N95 FFR reuse during critical shortages. However, autoclaving masks is not recommended by the evidence in this review. Any mask disinfected using these methods should be inspected for physical degradation before reuse.NOTE: The experiments summarized in this manuscript are performed under specialized laboratory conditions. Household appliances should not be used for any purposes that are not indicated in their manufacturer-supplied guidelines, including mask decontamination. Doing so may lead to damage or injury.

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For a cognitive radio (CR) user to dynamically access the available primary user channels, the spectrum sensing data is required at various locations; however, the data is not generally available at the points present in between the two spectrum sensors. To obtain this data, it is also not feasible to conduct the spectrum measurement surveys at every location. This calls for an interpolation‐based spectrum occupancy data collection in the space. Moreover, the information about the future primary user activity is necessary for highly enhanced dynamic channel allocation with better quality of experience (QoE) of CR users in terms of improved channel utilization and reduced spectrum sensing energy requirement. Most of the existing works are inclined toward either spatial spectrum interpolation or temporal spectrum prediction. In this work, a novel hybridized approach combining the Kriging‐based statistical spatial interpolation and the recurrent neural networks–based temporal prediction of the spectrum has been proposed to obtain the spectrum occupancy probability information using empirical spectrum measurements data in cellular CR networks. Furthermore, the aforementioned framework has been utilized for dynamic channel allocation with the help of a newly investigated CR channel allocation scheme. The corresponding results have been validated through various CR QoE measures and compared with the existing channel allocation strategies, where it is found that the proposed channel allocation scheme significantly outperforms the other schemes with the enhanced QoE of CR. Finally, a spatio‐temporal channel allocation map has been presented for secondary user to perform its best possible CR operation with efficient dynamic spectrum access.

Device-to-device (D2D) communication is a promising future wireless network technology that establishes a direct link between the devices in close vicinity. Along with the improved end-to-end latency and network rate, it also enhances the spectral and power efficiency. Most of the previous works on interference management and resource allocation have considered half-duplex (HD) D2D systems and have assumed that D2D pairs cannot access more than a single channel at a time and a cellular channel is assigned to at most one D2D pair. In this article, we investigate multiple-pair-multiple-channel (MPMC) allocation scenario over multiple-input-multiple-output-based full-duplex D2D networks.The idea is to maximize the aggregate sum data rate of the D2D network by optimal allocation of the resources and maintaining a desired threshold rate for the cellular users. The cross-tier interferences are intelligently handled by appropriate channel allocation and the co-tier interferences by proper power allocation.The efficacy of the proposed MPMC algorithm has been evaluated through rigorous simulations, and an appreciably better network rate has been found as compared with the single-pair-single-channel-based allocation. Moreover, by allowing more users to communicate in tandem, with enhanced average rate, the results also ensure a better opportunity of higher utilization of the scarce licensed cellular spectrum. The presented algorithm has also been compared with random and uniform based allocations and further analyzed in HD-MPMC communications.