Fit Testing Failure of Reprocessed "Duckbill"-Type N95 Masks.

OBJECTIVES: In response to worldwide shortages of N95 masks during the severe acute respiratory syndrome-coronavirus-2 pandemic, various strategies have been used. The Centers for Disease Control and Prevention recommend several strategies, including simple isolation to reprocessing methods using vaporized hydrogen peroxide to guide reuse of masks up to five times. National Institute for Occupational Safety and Health (NIOSH) quantitative fit testing was performed after five trials of donning and doffing in one cohort of new masks and two cohorts of repeatedly sterilized "duckbill"-type N95 masks. METHODS: One cohort of new masks and two cohorts of sterilized masks were repeatedly subjected to 35% vaporized hydrogen peroxide for either five or 10 cycles. Then, they were subjected to five trials of donning and doffing, with NIOSH quantitative fit testing performed after each wear cycle to assess for any degradation on fit performance caused by sterilization and/or repeated donning and doffing up to the recommended Centers for Disease Control and Prevention limit of five times. All of the fit testing was performed on a single volunteer. RESULTS: The means and 95% confidence intervals for each cohort and the individual results for each mask within each cohort were reported. A χ2 analysis showed significant differences in percentages of masks that pass fit testing in both recycled mask cohorts. CONCLUSIONS: These data show the variability of NIOSH fit testing results of both new and sterilized masks. The mask recycling program of our partner health systems thus discarded these types of masks due to the variable failure rate. Health systems should consider individual evaluation to inform their overall policies on mask reuse and recycling.

Quantitative analysis of cotton (Gossypium hirsutum) lint trash by fluorescence spectroscopy.

The presence of cotton plant botanical components, or trash, embedded in lint subsequent to harvesting and ginning is an important criterion in the classification of baled cotton by the U.S. Department of Agriculture Agricultural Marketing Service. The trash particles may be reduced in size to the point that specific trash types are not identifiable by image or gravimetric analysis, and it is desirable to quantify different trash types so that processing lines may be optimized for removal of the most problematic trash to enhance processing performance and cotton lint quality. Currently, there are no methods available to adequately quantify cotton lint trash based on botanical origin. The present work attempts to address this issue through the analysis by fluorescence spectroscopy of dimethyl sulfoxide extracts of mixtures of six botanical trash types. The fluorescence data are subsequently subjected to chemometric analysis. The resulting 6 partial least-squares calibration models obtained from 128 mixtures are demonstrated in the case of leaf and hull to be capable of predicting individual trash component concentrations with a high degree of confidence.

Flax-retting by polygalacturonase-containing enzyme mixtures and effects on fiber properties.

Enzyme-retting of flax was accomplished via individual treatment with four polygalacturonase (PGase) containing solutions of various fungal sources and the resulting fibers were characterized. The retting solutions were equilibrated to contain 2.19 U of PGase activity as determined via a dinitrosalicylic acid (DNS) reducing sugar assay. As compared with the buffer control, treatment with the various enzyme solutions increased the yield of fine fibers. Treatment with Aspergillus niger PGase resulted in a 62% increase in fine fiber yield as compared with the buffer control and fiber strength did not statistically differ (P