The increasing prevalence of infectious diseases in recent decades has posed a serious threat to public health. Routes of transmission differ, but the respiratory droplet or airborne route has the greatest potential to disrupt social intercourse, while being amenable to prevention by the humble face mask. Different types of masks give different levels of protection to the user. The ongoing COVID-19 pandemic has even resulted in a global shortage of face masks and the raw materials that go into them, driving individuals to self-produce masks from household items. At the same time, research has been accelerated towards improving the quality and performance of face masks, e.g., by introducing properties such as antimicrobial activity and superhydrophobicity. This review will cover mask-wearing from the public health perspective, the technical details of commercial and home-made masks, and recent advances in mask engineering, disinfection, and materials and discuss the sustainability of mask-wearing and mask production into the future.

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X-ray photoelectron spectroscopy (the deconvoluted high-resolution N ls core-level spectrum in particular) was used for the quantitative determination of the proportion of benzoid amine, quinoid imine, and protonated units in chemically synthesized polyaniline. This method allows the tracking of structural changes during polyaniline oxidation and reduction.

Polylactide (PLA) has been receiving significant attention in biopolymer research due to its excellent biodegradability, biocompatibility and sustainability. The mass production of PLA from renewable agricultural resources has delved this green material as a top alternative to replace the petroleum-based conventional polymers. However, the inherent weaknesses of PLA in its raw state such as brittleness, low heat distortion temperature and recrystallization rate, as well as the inadequate crystallization ability and degree after fast processing have limited the competitive edge of PLA over traditional synthetic plastics in industrial use or for biomedical applications. Being different from other types of biodegradable polymers, the diverse isomeric forms of PLA have provided great opportunities for thermal and mechanical enhancement through stereocomplexation formation. In this review, we present the most recent development in thermal and mechanical enhancement of PLA via stereocomplexation of PLA in different polymeric systems, including enantiomeric PLA homopolymers, PLA-based block and graft copolymers, as well as enantiomeric PLA materials having unique architectures such as cyclic, star, dendritic and comb-shaped. Insightful discussion on the influence of crystal structure and intermolecular interactions between PLLA and PDLA in the different polymeric systems on the enhanced performance of the resultant materials are provided. The enhanced PLA with diverse functions oriented toward engineering materials and their biosignificance in different areas are also covered in this review.

1. Oxidative stress is believed to be a pathogenetic factor in the development of diabetic complications. In the present study, we investigated the ethanolic extract of the aerial parts of Andrographis paniculata for antihyperglycaemic and anti-oxidant effects in normal and streptozotocin-induced type I diabetic rats. 2. Normal and diabetic rats were randomly divided into groups and treated orally by gavage with vehicle (distilled water), metformin (500 mg/kg bodyweight) or the extract (400 mg/kg bodyweight), twice a day for 14 days. 3. At the end of the 14 day period, the extract, like metformin, significantly increased bodyweight (P < 0.01) and reduced fasting serum glucose in diabetic rats (P < 0.001) when compared with vehicle, but had no effect on bodyweight and serum glucose in normal rats. Levels of liver and kidney thiobarbituric acid-reactive substances (TBARS) were significantly increased (P < 0.0001, P < 0.01, respectively), while liver glutathione (GSH) concentrations were significantly decreased (P < 0.005) in vehicle-treated diabetic rats. Liver and kidney TBARS levels were significantly lower (P < 0.0001, P < 0.005, respectively), whereas liver GSH concentrations were significantly higher (P < 0.05) in extract- and metformin-treated diabetic rats compared with vehicle-treated diabetic rats. Andrographis paniculata significantly decreased kidney TBARS level (P < 0.005) in normal rats. Hepatic superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities were significantly lower in vehicle-treated diabetic rats compared with vehicle-treated normal rats. The extract, as well as metformin, significantly increased the activity of SOD and CAT, but had no significant effect on GSH-Px activity in diabetic rats. The extract and metformin did not produce significant changes in the activity of these anti-oxidant enzymes in normal rats. 4. Our results show that oxidative stress is evident in streptozotocin-diabetic rats and indicate that the ethanolic extract of A. paniculata not only possesses an antihyperglycaemic property, but may also reduce oxidative stress in diabetic rats.

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