ABSTRACT
Due to the excessive use of disposable face masks during the COVID-19 pandemic, their accumulation has posed a great threat to the environment. In this study, we explored the fate of masks after being disposed in landfill. We simulated the possible process that masks would experience, including the exposure to sunlight before being covered and the contact with landfill leachate. After exposure to UV radiation, all three mask layers exhibited abrasions and fractures on the surface and became unstable with the increased UV radiation duration showed aging process. The alterations in chemical groups of masks as well as the lower mechanical strength of masks after UV weathering were detected to prove the happened aging process. Then it was found that the aging of masks in landfill leachate was further accelerated compared to these processes occurring in deionized water. Furthermore, the carbonyl index and isotacticity of the mask samples after aging for 30 days in leachate were higher than those of pristine materials, especially for those endured longer UV radiation. Similarly, the weight and tensile strength of the aged masks were also found lower than the original samples. Masks were likely to release more microparticles and high concentration of metal elements into leachate than deionized water after UV radiation and aging. After being exposed to UV radiation for 48 h, the concentration of released particles in leachate was 39.45 muL/L after 1 day and then grew to 309.45 muL/L after 30 days of aging. Seven elements (Al, Cr, Cu, Zn, Cd, Sb and Pb) were detected in leachate and the concentration of this metal elements increased with the longer aging time. The findings of this study can advance our understanding of the fate of disposable masks in the landfill and develop the strategy to address this challenge in waste management. Copyright © 2023 Elsevier B.V.
ABSTRACT
Objectives:Nylon fiber is a synthetic polymer that possesses outstanding physical and chemical properties such as good strength, flexibility, and air permeability. Nylon fiber has been widely used worldwide for various products including bedding, wipes, clothing, surgical gowns, wig, etc. The outbreak of COVID-19 boosts a surge in consumer demand for antibacterial fabrics that have the ability of resistance to bacteria attack because textile materials are good medium for microorganism growth and breeding. The present study thus aims to develop a durable antibacterial nylon fabric that could be used as wig against householdwashing. Thiswig would provide a solution for patients need chemotherapy to increase their self-confidence. Methods: The method of pad-dry-cure process was used to treat the nylon fabric samples. The N1 finishing formulation was prepared by adding binder and cationic antibacterial agent to deionized water. N2 finishing solution was prepared by mixing binder and inorganic antibacterial agent in deionized water. The sample was first padded with the pre-prepared finishing formulation. Afterwards, the sample was dried in an oven at 100oC for 2 min and then cured at 150oC for 1 min. After antibacterial finishing, the samples were washed with shampoo for different cycles at room temperature. Each cycle lasts 1 min. Finally, the antibacterial property of treated samples was qualitatively conducted against gram-positive S. aureus and gram-negative K. pneumoniae according to AATCC TM 147-2011. Results: The antibacterial results demonstrate that both samples treated with N1 and N2 have excellent antibacterial activities, particularly against S. aureus. However, after washing with shampoo, N1 samples show a distinct decrease in the inhibition zone and the samples fail to kill bacteria. By contrast, N2 samples show satisfactory antibacterial properties after 52 washing cycles. Moreover, there is no significant change in the antibacterial activity of N2 samples after 52 washing cycles. This suggests that the inorganic antibacterial agent has stronger affinity to nylon fiber than cationic antibacterial agent treated nylon fabric presents durable antibacterial activity. Conclusions: The inorganic antibacterial agent shows strong affinity to nylon fiber and can be used for developing durable antibacterial nylon fabrics against washing.
ABSTRACT
In this work, we present a UHF-RFID-based noninvasive sensor to measure the concentration of ethanol in water using the volume fraction of liquids in mixture solutions. The sensing system operates at the UHF band (860-928 MHz). The concentration of ethanol in water affects the dielectric properties of the solution and therefore the antenna sensitivity of the RFID tag. This sensor operates by measuring the change in permittivity of a solution because of the change in concentration of ethanol in water. We propose a flexible RFID-Tag sensor a low-cost alternative to identify the possible sensitivity of tag changes and is able to detect a variation of 25% in ethanol in 9 ml of deionized water (DI-Water). The solution is useful in avoiding counterfeit ethanol solutions that may be toxic. The experimental setup is inexpensive, portable, quick, and contactless. We present results for ethanol solutions ranging from 25% to 100% in a small tube container. © 2022 IEEE.
ABSTRACT
The COVID-19 pandemic has required novel solutions, including heat disinfection of personal protective equipment (PPE) for potential reuse to ensure availability for healthcare and other frontline workers. Understanding the efficacy of such methods on pathogens other than SARS-CoV-2 that may be present on PPE in healthcare settings is key to worker safety, as some pathogenic bacteria are more heat resistant than SARS-CoV-2. We assessed the efficacy of dry heat treatment against Clostridioides difficile spores and Mycobacterium tuberculosis (M. tb) on filtering facepiece respirator (FFR) coupons in two inoculums. Soil load (mimicking respiratory secretions) and deionized water was used for C. difficile, whereas, soil load and PBS and Tween mixture was used for M. tb. Dry heat treatment at 85 °C for 240 min resulted in a reduction equivalent to 6.0-log10 CFU and 7.3-log10 CFU in C. difficile spores inoculated in soil load and deionized water, respectively. Conversely, treatment at 75 °C for 240 min led to 4.6-log10 CFU reductions in both soil load and deionized water. C. difficile inactivation was higher by >1.5-log10 CFU in deionized water as compared to soil load (p < 0.0001), indicating the latter has a protective effect on bacterial spore inactivation at 85 °C. For M. tb, heat treatment at 75 °C for 90 min and 85 °C for 30 min led to 8-log10 reduction with or without soil load. Heat treatment near the estimated maximal operating temperatures of FFR materials (which would readily eliminate SARS-CoV-2) did not achieve complete inactivation of C. difficile spores but was successful against M. tb. The clinical relevance of surviving C. difficile spores when subjected to heat treatment remains unclear. Given this, any disinfection method of PPE for potential reuse must ensure the discarding of any PPE, potentially contaminated with C. difficile spores, to ensure the safety of healthcare workers.
ABSTRACT
An X-band, free-space microwave sensor consisting of 30 radial spokes connected in a central hub with a gap region was designed, fabricated and tested. The sensor structure results in an electric dipole at 10 GHz with a split circular disc capacitor at the center. Viruses, dust, and soot particles in the gap region change the sensor’s impedance and its reflection coefficient monitored by a horn antenna and a network analyzer. The sensor sensitivity was 85.02 MHz/microliter for deionized water, 89.5 MHz/microliter for uninfected saliva, and 94.6 MHz/microliter for SARS-COV-2 infected saliva with 103 viruses/μL. Its sensitivity to a dielectric sample (ερ~5.84) was 3.23 MHz/mm3, and for iron particles was 16.25 MHz/mm3. All these samples were smaller than λ/30 at 10 GHz and could not be detected on uniform dielectric or metallic substrates without the spoke structure. A 2x2 array of spoke sensors was also constructed and tested as a feasibility study for designing larger metamaterial (MTM) periodic arrays. IEEE