Leo Lit Man Poon | Searcharxiv

arXiv2025

A novel approach to profile global circulation pathway of SARS-CoV-2 variants by site-based mutation dynamics

The genetic evolution of SARS-CoV-2 has caused recurring epidemic waves, understanding its global dispersal patterns is critical for effective surveillance. We developed the Site-based mutation dynamics - Equal Power Sampling (S-EPS) framework, a phylogenetic-free, bias-correcting framework for profiling viral source-sink dynamics. Applying S-EPS to 6.6 million SARS-CoV-2 genomes (March 2020 - June 2024) from 13 regions worldwide, we identified Africa and the Indian subcontinent as the predominant sources of key mutations. Southeast Asia serves as an early transmission hub, while Russia and South America mainly acted as sinks. Key mutations took longer to establish fitness in source regions than externally. Once an amino acid substitution on the receptor-binding domain reached 1% prevalence in major sources, there is an 80% probability it would spread elsewhere, with a 2-month median lead time (IQR: 1-4). Our findings underscore the importance of genetic surveillance, with S-EPS offering enhanced capability for monitoring emerging viral threats.

q-bio.PE↗

arXiv2022

Ultrafast disinfection of SARS-CoV-2 viruses

The wide use of surgical masks has been proven effective for mitigating the spread of respiration diseases, such as COVID-19, alongside social distance control, vaccines, and other efforts. With the newly reported variants, such as Delta and Omicron, a higher spread rate had been found compared to the initial strains. People might get infected even by inhaling fewer loading of viruses. More frequent sterilization of surgical masks is needed to protect the wearers. However, it is challenging to sterilize the commodity surgical masks with a fast and effective method. Herein, we reported the sterilization of the SARS-CoV-2 viruses within an ultra-short time, while retaining the mask performance. Silver thin film is coated on commercial polyimide film by physical vapor deposition and patterned by laser scribing to form a Joule heating electrode. Another layer of the gold thin film was coated onto the opposite side of the device to promote the uniformity of the Joule heating through nano-heat transfer regulation. As a result, the surgical mask can be heated to inactivation temperature within a short time and with high uniformity. By Joule-heating the surgical mask with the temperature at 90 °C for 3 minutes, the inactivation of the SARS-CoV-2 showed an efficacy of 99.89%. Normal commodity surgical masks can be sterilized faster, more frequently, and efficiently against SARS-CoV-2 viruses and the new invariants.

physics.med-ph↗