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.

Abstract. This paper discusses the phase transformation of diamond cubic silicon under nano-indentation with the aid of molecular dynamics analysis using the Tersoff potential. By monitoring the positions of atoms within the model, the microstructural changes as silicon transforms from its diamond cubic structure to other phases were identified. The simulation showed that diamond cubic silicon transforms into a body-centred tetragonal form (β-silicon) upon loading of the indentor. The change of structure is accomplished by the flattening of the tetrahedron structure in diamond cubic silicon. Upon unloading, the body-centred tetragonal form transforms into an amorphous phase accompanied by the loss of long-range order of the silicon atoms. By performing a second indentation on the amorphous zone, it was found that the body-centred-tetragonal-to-amorphous phase transformation could be a reversible process.

Herein we present a lab-chip device for highly efficient and rapid detection of circulating tumor cells (CTCs) from whole blood samples. The device utilizes a microfabricated silicon microsieve with a densely packed pore array (10(5) pores per device) to rapidly separate tumor cells from whole blood, utilizing the size and deformability differences between the CTCs and normal blood cells. The whole process, including tumor cell capture, antibody staining, removal of unwanted contaminants and immunofluorescence imaging, was performed directly on the microsieve within an integrated microfluidic unit, interconnected to a peristaltic pump for fluid regulation and a fluorescence microscope for cell counting. The latter was equipped with a dedicated digital image processing program which was developed to automatically categorize the captured cells based on the immunofluorescence images. A high recovery rate of >80% was achieved with defined numbers of MCF-7 and HepG2 cancer cells spiked into human whole blood and filtered at a rapid flow rate of 1 mL min(-1). The device was further validated with blood drawn from various cancer patients (8 samples). The whole process, from sample input to result, was completed in 1.5 h. In addition, we have also successfully demonstrated on-microsieve fluorescence in situ hybridization for single cell molecular analysis. This simple method has great potential to supplant existing complex CTC detection schemes for cancer metastasis analysis.

Id proteins are a class of dominant-negative antagonists of helix-loop-helix transcription factors and have been shown to control differentiation of a variety of cell types in diverse organisms. Although the importance of Id1 in tumor endothelial cells is well established, the expression and role of the Id1 protein in human cancer cells is controversial. To explore this issue, we developed and characterized a highly specific rabbit monoclonal antibody against Id1 to assess its expression in human breast, prostate, and bladder malignancies. Our results show that in usual types of human mammary carcinomas, the Id1 protein is expressed exclusively in the endothelium. Interestingly, we detected nuclear expression of the Id1 protein in the tumor cells in 10 of 45 cases of poorly differentiated and highly aggressive carcinoma with metaplastic morphology. Similarly, only 1 of 30 prostate cancer samples showed Id1-positive tumor cells, whereas in almost all, endothelial cells showed high Id1 expression. Intriguingly, whereas normal prostate glands do not show any Id1 protein expression, basal layer cells of benign prostate glands in proximity to tumors expressed high levels of the Id1 protein.In contrast to the lack of Id1 expression in the usual types of mammary and prostate cancers, the majority of transitional cell bladder tumors showed Id1 protein expression in both tumor and endothelial cells. These results suggest that further refinement of Id1 expression patterns in a variety of tumor types will be necessary to identify and study the functional roles played by Id1 in human neoplastic processes. (Cancer Res 2006; 66(22): 10870-7)