Flow dynamic of human cough and measuring techniques: A review

Coughing is one of the most important respiratory activities for air transmitted pathogens. It is essential to understand the dispersion of exhaled particles when coughing to improve the prevention measure and reduce the cross-infection risk. However, cough flow structure is complex and influenced by many parameters. Simplifications are often made to the initial flow condition when simulating the transport of particles expelled during coughing in laboratory or numerical studies . This study conducts a systematic literature review on human cough, especially focusing on flow dynamic characterization. First, the measuring techniques for identifying the airflow characteristic are summarized. The boundary conditions for cough, such as flow profile, flow direction, cough duration and are compared between different studies. Finally, the vortex structure of cough and its impact on cough particle dispersion is discussed

Intervention of personalized ventilation on interpersonal airborne disease transmission

Personalized ventilation (PV) has been integrated to reduce the risk of interpersonal infection exposure in the office environment. Some studies showed that PV systems may increase occupants’ risk of airborne infection. Therefore, the aim of this study is to investigate the intervention of PV on interpersonal airborne disease transmission in office environment. A three-dimensional computational fluid dynamics model (CFD) was developed and experimentally validated in a clean chamber. Then the validated CFD model was used to calculate the diffusion of exhaled droplets under different particle size. Results showed at the size of 0.7μm particles, compared to pure mixing ventilation, the personal ventilation of 6L/s reduced the inhalation fraction （IF）from 0.121% to 0.092%，and the reduction ratio of IF is 23.96%. As of 5μm, the IF also decreased from 0.165% to 0.102%, and the reduction ratio of IF is 38.18%. The percentage of 50μm particles deposited on the ground rises from 6.29% to 43.22% of exhaled particles. Therefore, the personalized ventilation can reduce the risk of inhalation in exposed person, and for large size particles, the number of particles falling on the floor increased greatly, which lead to the risk of resuspension increases. The results may be helpful for maximizing the effect of PV in interpersonal airborne disease control

Integrating MWCNTs-doped MXene with multi-spiral-channel architecture enables field effect transistor biosensor capable of ultrasensitive determination of methotrexate

Previous breakthroughs in biosensor diagnostics stem from engineering and nanocomposites. Accurately detecting low-abundance compounds such as methotrexate in complex biospecimens (e.g. serum) is an important clinical challenge. To address this issue, a MWCNTs-doped MXene-based multi-spiral-channel field-effect transistor (MMSFETs) biosensor was constructed for ultrasensitive quantification of methotrexate. Our integrated biosensor exhibited following merits: a) The synergetic performance of MXene and MWCNTs for enhanced transconductance (0.63 mS) and detection capability (methotrexate, linear range of 0.001–100 μM and LOD down to 0.352 nM); b) Favorable selectivity, stability (one month), reproducibility (RSD = 0.99%, n = 7) for biosensing of methotrexate; c) Acceptable clinical performances on comparisons of MMFETs against commercial Abbott automatic immunoluminescence instrument (ARCHITECT I1000): favorable linearity and correlation coefficient (YMMSFETs = 1.4305 × Xtargeted concentration + 4.3791 with R2 = 0.949), significant p value (7.68E-12 < 0.001) and diagnosis capability of AUC (0.9907). Those advantages are anticipated to pave an avenue to design of the FETs-based biosensor towards the point-of-care diagnostics applications

Experimental of natural ventilation in a semi-transparent photovoltaic double skin façade in summer

Semi-transparent photovoltaic double skin façade (STPV-DSF) is a novel structure which integrates photoelectric, photothermal, ventilation and energy-saving features, which proves to be extremely attractive and promising. In this study, a full-scale experimental system was built, airflow and heat transfer in a rectangular cavity with different transmittance (τ) and different ventilation modes in summer that studies a STPV-DSF and includes natural ventilation were examined experimentally. The Rayleigh number and Nusselt number of STPV-DSF is significantly higher than that of traditional DSF. This also means stronger intense flow. And the maximum temperature difference at night between mode 1 and mode 2 can reach 7.3°C. When the external air circulation mode is switched to the external and internal mode, the indoor temperature drops by 2.88°C in ten minutes. Therefore, making fully use of natural ventilation can effectively reduce the cooling load of air conditioning in summer. The solar radiation intensity is proved to have the greatest influence on the cavity temperature, followed by the transmittance, and the the ventilation mode least influence. Applying naturally ventilated STPV-DSF would be a new efficient way for the curtain wall buildings to meet the task of sustainable building design