Fabrication and performance of a stable micro/nano composite electret filter for effective PM2.5 capture.

Airborne particulate matter (PM) pollution has raised serious concerns over both the global climate and public health. Therefore, there is an urgent need for air filters of high-efficiency and energy-saving. Pore structure optimization and electret enhancement are feasible means to improve their filtration performance. Herein, a novel sandwich-structured electret composite filter with a low pressure drop and robust filtration stability was successfully designed and fabricated. The composite filter was composed of fluffy PS microfibers with large electric resistivity and high porosity, and PAN nanofibers with high polarity and small pore size. Benefiting from the fluffy structure constructed by electrospinning at the right humidity, the tortuous pore channels created by the appropriate mixing of microfibers and nanofibers, and the abundant static charges generated by the hybrid of polar and nonpolar polymer materials, the PS/PAN/PS composite filter possessed a high filtration efficiency of 99.96% for particles of 0.30 µm, a low pressure drop of 54 Pa and a satisfactory quality factor value of 0.1449 Pa-1 at an airflow velocity of 5.3 cm/s. In particular, the composite filter exhibited better electret stability and PM2.5 loading performance than the commercial ones, which guarantees its long-term storage and usage.

A modified in vitro stripping method to automate the calculation of geometry of corneocytes imaged with fluorescent microscopy: example of moisturizer treatment.

BACKGROUND/PURPOSE: To develop a modification of the stripping method allowing quick automated processing of corneocyte samples to study human skin conditions. Although the previous scrubbing technique and stripping method can provide sufficient information about human corneocytes, they are either subject to artifacts or involve time-consuming data processing. METHODS AND MATERIALS: In the first stage, an adhesive tape is used to collect corneocytes as in the regular stripping method. Then, a D-squame skin indicator is used to divide the collected corneocytes into a lesser populated sample, in which more individual corneocytes can be observed with the help of fluorescent microscopy after dye staining. The method was applied to study the change of corneocytes after moisturizer (glycerin) treatment. RESULTS: The modified stripping method described allows the automated processing of the geometrical characteristics of corneocytes. Data for several hundreds of corneocytes can easily be collected. The analysis of glycerin treatment demonstrated a high sensitivity for the method. An average increase of the corneocyte area of 5.1% was found after 9 days of treatment (the accuracy of the method was 0.5%). CONCLUSION: The method described is suitable for the automated data processing. It allows for the reliable detection of the expansion of the average area of corneocytes after 9 days of daily glycerin treatment.

Sequencing of 50 human exomes reveals adaptation to high altitude.

Residents of the Tibetan Plateau show heritable adaptations to extreme altitude. We sequenced 50 exomes of ethnic Tibetans, encompassing coding sequences of 92% of human genes, with an average coverage of 18x per individual. Genes showing population-specific allele frequency changes, which represent strong candidates for altitude adaptation, were identified. The strongest signal of natural selection came from endothelial Per-Arnt-Sim (PAS) domain protein 1 (EPAS1), a transcription factor involved in response to hypoxia. One single-nucleotide polymorphism (SNP) at EPAS1 shows a 78% frequency difference between Tibetan and Han samples, representing the fastest allele frequency change observed at any human gene to date. This SNP's association with erythrocyte abundance supports the role of EPAS1 in adaptation to hypoxia. Thus, a population genomic survey has revealed a functionally important locus in genetic adaptation to high altitude.