Regulation of polylactic acid using irradiation and preparation of PLA–SiO2–ZnO melt-blown nonwovens for antibacterial and air filtration† † Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d2ra08274h

Since the COVID-19 pandemic, polypropylene melt-blown nonwovens (MBs) have been widely used in disposable medical surgical masks and medical protective clothing, seriously threatening the environment. As a bio-based biodegradable polymer, polylactic acid (PLA) has attracted great attention in fabricating MBs. However, there are still issues with the undesirable spinnability of PLA and the limited filtration and antibacterial performance of PLA MBs. Herein, a high-efficiency, low-resistance, and antibacterial PLA filter is fabricated by melt-blown spinning and electret postprocessing technology. The irradiation technique is used to tune PLA chain structure, improving its spinnability. Further, silica (SiO2) nanoparticles are added to enhance the charge storage stability of PLA MBs. With a constant airflow rate of 32 L min−1, the PLA-based MBs exhibit a high particulate filtration efficiency of 94.8 ± 1.5%, an ultralow pressure drop of 14.1 ± 1.8 Pa, and an adequate bacterial filtration efficiency of 98 ± 1.2%, meeting the medical protective equipment standard. In addition, the zinc oxide (ZnO) masterbatches are doped into the blend and the antibacterial rate of PLA-based MBs against Escherichia coli and Staphylococcus aureus is higher than 99%. This successful preparation and modification method paves the way for the large-scale production of PLA MBs as promising candidates for high-efficacy and antibacterial filters. PLA MBs with high filtration efficiency and antibacterial activity were prepared by reducing viscosity by irradiation and blending ZnO and SiO2.

Regulation of polylactic acid using irradiation and preparation of PLA-SiO2-ZnO melt-blown nonwovens for antibacterial and air filtration.

Since the COVID-19 pandemic, polypropylene melt-blown nonwovens (MBs) have been widely used in disposable medical surgical masks and medical protective clothing, seriously threatening the environment. As a bio-based biodegradable polymer, polylactic acid (PLA) has attracted great attention in fabricating MBs. However, there are still issues with the undesirable spinnability of PLA and the limited filtration and antibacterial performance of PLA MBs. Herein, a high-efficiency, low-resistance, and antibacterial PLA filter is fabricated by melt-blown spinning and electret postprocessing technology. The irradiation technique is used to tune PLA chain structure, improving its spinnability. Further, silica (SiO2) nanoparticles are added to enhance the charge storage stability of PLA MBs. With a constant airflow rate of 32 L min-1, the PLA-based MBs exhibit a high particulate filtration efficiency of 94.8 ± 1.5%, an ultralow pressure drop of 14.1 ± 1.8 Pa, and an adequate bacterial filtration efficiency of 98 ± 1.2%, meeting the medical protective equipment standard. In addition, the zinc oxide (ZnO) masterbatches are doped into the blend and the antibacterial rate of PLA-based MBs against Escherichia coli and Staphylococcus aureus is higher than 99%. This successful preparation and modification method paves the way for the large-scale production of PLA MBs as promising candidates for high-efficacy and antibacterial filters.

Collective synthesis of aspulvinone and its analogues by vinylogous aldol condensation of substituted tetronic acids with aldehydes.

A mild, modular and efficient synthetic method with broad substrate scope was developed for aspulvinones. Nine natural aspulvinones were synthesized, six of which were for the first time. The aldol condensation delivered Z-configuration products predominantly in MeCN. Meanwhile, alkoxy exchange occurred in MeOH and EtOH. Aspulvinone O and E, and substrate 49, 50, and 51 exhibited modest anti-SARS-CoV-2 activity in a high-throughput screening and enzyme kinetics assay.

Collective synthesis of aspulvinone and its analogues by vinylogous aldol condensation of substituted tetronic acids with aldehydes† † Electronic supplementary information (ESI) available. CCDC 2183460 and 2204675–2204677. For ESI and crystallographic data in CIF or other electronic format see DOI: https://doi.org/10.1039/d2ra08133d

A mild, modular and efficient synthetic method with broad substrate scope was developed for aspulvinones. Nine natural aspulvinones were synthesized, six of which were for the first time. The aldol condensation delivered Z-configuration products predominantly in MeCN. Meanwhile, alkoxy exchange occurred in MeOH and EtOH. Aspulvinone O and E, and substrate 49, 50, and 51 exhibited modest anti-SARS-CoV-2 activity in a high-throughput screening and enzyme kinetics assay. A mild, modular and efficient synthetic method with broad substrate scope was developed for aspulvinones. Some of them exhibited anti-SARS-CoV-2 activity in a high-throughput screening and enzyme kinetics assay.

Furin: A Potential Therapeutic Target for COVID-19.

COVID-19 broke out in the end of December 2019 and is still spreading rapidly, which has been listed as an international concerning public health emergency. We found that the Spike protein of SARS-CoV-2 contains a furin cleavage site, which did not exist in any other betacoronavirus subtype B. Based on a series of analysis, we speculate that the presence of a redundant furin cut site in its Spike protein is responsible for SARS-CoV-2's stronger infectious nature than other coronaviruses, which leads to higher membrane fusion efficiency. Subsequently, a library of 4,000 compounds including approved drugs and natural products was screened against furin through structure-based virtual screening and then assayed for their inhibitory effects on furin activity. Among them, an anti-parasitic drug, diminazene, showed the highest inhibition effects on furin with an IC50 of 5.42 ± 0.11 µM, which might be used for the treatment of COVID-19.

How to prevent in-hospital COVID-19 infection and reassure women about the safety of pregnancy: Experience from an obstetric center in China.

OBJECTIVE: This study aimed to describe the emergency responses to coronavirus disease 2019 (COVID-19) for pregnant patients at our hospital and their effect on hospital operations and patients' outcomes. METHODS: We developed strategies to prevent hospital-associated transmission of COVID-19 in obstetric care. Infrastructure, including the fever clinic and wards, were modified. Outpatient volume was controlled and screening processes were strictly performed. Verification of the virus was compulsory for non-surgery and non-emergency patients. Emergency operations were performed in a negative pressure theater with surgeons fully protected. Outcomes were analyzed and the patients' characteristics were evaluated. The effect of intervention on depressed and anxious patients was assessed. Data from the first 2 months of 2019 and 2020 were compared. RESULTS: No in-hospital COVID-19 infections occurred in our unit. During the epidemic, patient volume significantly decreased. While major characteristics of patients were similar, a higher prevalence of gestational hypertension was found in 2020 than in 2019. Psychological interventions showed optimistic effects in ameliorating depression and anxiety at the beginning of the COVID-19 pandemic. CONCLUSIONS: Our strategies were effective in preventing in-hospital infection of COVID-19 and reassuring women about the safety of pregnancy. Monitoring and managing psychological issues were necessary during this critical period.