ABSTRACT
Particulate air pollution represented by PM2.5 is one of the biggest environmental challenges in the 21st century. Especially in 2020, the global outbreak of COVID-19 has brought new challenges to melt-blown filter materials, such as the attenuation of filtration efficiency with breathing, even no filtration effect for viruses as their smaller diameter, the sharp decline of filter efficiency after oily filtration cycle, and its limit in some explosive occasions. Here, using the diameter difference of polystyrene (PS), polyvinylidene fluoride (PVDF) and nylon 6(PA6) fibers, we report a multistage structure nanofiber membrane (PS/PVDF/PA6&Ag MSNMs) with high efficiency, low resistance and antibacterial effect by constructing gradient pore structure and introducing silver nanoparticles (Ag NPs), overcoming the above defects. The average filtration efficiency of PS/PVDF/PA6&Ag MSNMs for diisooctyl sebacate (DEHS) monodisperse particles from 0.2 μm to 4.9 μm was 99.88%, and the pressure drop was only 128 Pa. After repeated circulation for 100 times, the filtration efficiency and pressure drop remained stable. Above all, the antibacterial nanofiber membrane with high efficiency and low resistance has been preliminarily constructed, the future research will further focus on the performance after circulation. © 2023 Elsevier Ltd
ABSTRACT
The key to fight against a global pandemic such as COVID-19 is to have low-cost, reliable and fast response diagnostic tools. Electronic biosensors are preferred because of their ease of integration into current centralized health care networks and integration with modern point-of-care testing (POCT) devices. Printed electronic sensors provide a sensitive and reliable diagnostic platform to aid in controlling transmissible diseases. In this work, we demonstrate a fully printed capacitive biosensor. The sensor uses coplanar electrodes, coupled with capture antibodies immobilized on microporous Polyvinylidene-fluoride (PVDF) film to detect the SARS-CoV-2 spike protein in spiked buffer solutions. Antibody immobilization on PVDF surface is confirmed with confocal fluorescent imaging microscopy. Gold nanoparticle (GNP) tagged detection antibodies are also introduced to provide increased sensitivity. The gold nanoparticles provide a reflectance layer which leads to increased capacitance. This increased capacitance can be measured directly and has demonstrated the ability to screen for spiked samples with statistical significance. This fully printed capacitive immunoassay has the potential to be used as a transmissible disease screening and vaccine efficacy assessment tool for resource-limited areas. IEEE
ABSTRACT
COVID-19 is a pandemic that affected the majority of countries of the world. After the COVID-19 outburst, the Indian Government declared the complete lockdown starting on the night of 24 March 2020. The lockdown period is in its 4th phase. In the recent year it has been very fascinating to remind that the behaviour in the environment is vastly optimistic and all layers of the earth are under the repairing mode during the lockdown. With these healing environments, the conditions of the Yamuna River water in Mathura (polluted river) have also been found to be upgrading. In this present concern, we work on the concentration of BOD, COD, pH, and other physicochemical parameters for the study, i.e. TDS, Chlorides, Alkalinity, Magnesium, Calcium, Fluoride, Sulphate, Nitrate, Hardness and Total Coliform of Yamuna River (Mathura), respectively, which was found to be reduced as compared to pre-lockdown concentration, i.e. 57, 57, 3.6, 11.7, 5.1, 7.4, 9.5, 4.2, 62.5, 14.8, 33.3, and 4.5%. In the present work, the water of Yamuna River was analysed during the lockdown phase in ITL Labs Pvt. Ltd., Delhi (India). Yamuna River showed a better quality of water during the lockdown. As per results and trend analysis, the value was reducing in this lockdown phase, which is a matter of concern. Major locations of Yamuna water sample collection are Mathura region, i.e. adjacent to the road 50 m from Adda village in Naujheel of Mathura district in Uttar Pradesh. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
ABSTRACT
The demand for air filtration products has increased significantly with the aggravation of air pollution and the pandemic of coronavirus disease (COVID-19). It is urgently needed to develop an air filtration membrane that exhibits lasting filtration performance and antibacterial activity. Herein, we report a large-scale blow spinning technique to produce polyvinylidene fluoride (PVDF) nanofiber membranes for highly efficient air mechanical filtration and its antibacterial modification by adding the silver nanoparticles (AgNPs). The PVDF nanofiber membrane with an area density of only 1.0 g/m2 exhibits the highest filtration efficiency of 98.63% for the particle with a size of 0.3 μm. After eliminating static electricity, there is almost no reduction in the filtration efficiency of particulate matter with a size larger than 1 μm and only 4.69% decrease in the particulate matter with a size of 0.5 μm. Hence, the PVDF nanofiber membrane with nanostructures for air filtration works mainly by the means of mechanical filtration. To inhibit the survival or growth of the intercepted bacteria on the membrane, the PVDF/AgNPs nanofiber membrane was fabricated by adding AgNPs to PVDF nanofibers, which exhibits the strongest antibacterial activity of more than 99% and an excellent filtration efficiency similar to that without adding AgNPs. The nanofiber membrane with antibacterial activity is expected to extend the service or storage time or be reused without loss of filtration performance. Additionally, large-scale production of nanofiber filtration membranes has been realized using a multi-needle blow spinning machine. © 2022 American Chemical Society.
ABSTRACT
Comprehensive analysis of respiratory gases may provide noninvasive health monitoring of lung diseases, such as corona virus 2019 pneumonia. Here, a self-powered wearable mask has been fabricated for real-time monitoring and uploading exhaling oxygen information. Tetrapod ZnO (T-ZnO) nanostructures are hybridized with polyvinylidene fluoride (PVDF) that adhere to flexible fabric substrate on a mask. The piezoelectric effect of T-ZnO/PVDF is coupled with the gas sensing properties. The sensing unit can convert breath energy into piezoelectric signal without any external power supply, and the outputting piezoelectric voltage increases with increasing oxygen concentration, acting as the sensing signal. The sensing unit integrated with data processing module and wireless Bluetooth module can transmit the exhaling oxygen information to the mobile device, realizing real-time monitoring the oxygenation capacity of the lungs. This self-powered wearable approach can promote the lung diagnosis outside of clinical settings. © 2022 IOP Publishing Ltd.