Presence Of Microfibers Research Articles

Impacts of elevated temperature, decreased salinity and microfibers on the bioenergetics and oxidative stress in eastern oyster, Crassostrea virginica

Projected increases in temperature and decreases in salinity associated with global climate change will likely have detrimental impacts on eastern oyster, Crassostrea virginica, as these variables can influence physiological processes in these keystone species. We set out to determine how the interactive effects of temperature (20 °C or 27 °C) and/or salinity (27‰ or 17‰) impacted the energetic reserves, aerobic and anaerobic metabolism, and changes to oxidative stress or total antioxidant potential as a consequence of an altered environment over a 21-day exposure. Gill and adductor muscle were used to quantify changes in total glycogen and lipid content, Electron Transport System and Citrate Synthase activities, Malate Dehydrogenase activity, Protein Carbonyl formation, lipid peroxidation, and total antioxidant potential. A second exposure was performed to determine if these environmental factors influenced the ingestion of microfibers, which are now one of the leading forms of marine debris. Elevated temperature and the combination of elevated temperature and decreased salinity led to an overall decline in oyster mass, which was exacerbated by the presence of microfibers. Changes in metabolism and oxidative stress were largely influenced by time, but exposure to elevated temperature, decreased salinity, the combination of these stressors or exposure to microfibers had small impacts on oyster physiology and survival. Overall these studies demonstrate that oyster are fairly resilient to changes in salinity in short-term exposures, and elevations in temperature or temperature combined with salinity result in changes to the oyster energetic response, which can be further impacted by the presence of microfibers.

Electrowetting-on-dielectric behavior of aqueous droplets and gold nanofluid on an electrospun poly(vinyl chloride) microfiber layer

Morphology and wettability of dielectric layers are crucial properties that affect the electrowetting-on-dielectric (EWOD) performance of a working liquid. In this work, the use of a poly(vinyl chloride) (PVC) microfiber-modified PVC dielectric layer as an electrowetting-on-dielectric (EWOD) substrate is explored. Imaging with scanning electron and atomic force microscopy revealed intertwined microfibers on the original PVC film after PVC deposition via electrospinning. Hydrophobicity of the PVC layer was enhanced by the presence of microfibers, with the contact angle (CA) for a water droplet increasing from 84.9° to 123.9°. EWOD behavior of various liquids on the microfiber-modified PVC layer was investigated within a DC voltage range of 0 to 200 V DC. Gold nanofluid exhibited the largest change in CA of 57°, while smaller changes were observed for KOH (19.6°), KCl (21.2°), and water (21°). A mechanism explaining the observed reduction in contact angle for a gold nanofluid droplet is presented. Our results suggest the promising potential of PVC film-PVC microfiber as a hydrophobic dielectric material for EWOD applications involving diverse liquids, including gold nanofluids.

Microfibers in anaerobic digestion: Effect of ozone pretreatment

Wastewater treatment plants receive significant microplastics, which are eventually discharged into the environment. Previous studies indicated that over 90% of microplastics, especially microfibers from laundry wastewater, are retained in primary sludge. The effect of microfibers from household laundry on anaerobic digestion has yet to be fully understood, which is the objective of the present study. The results in this study showed a positive correlation between methane production and the presence of microfibers. Compared to the control, the methane production increased by 2%, 27% and 43% with 20 mg/L, 100 mg/L and 1000 mg/L microfibers spiked into primary sludge, respectively. The present study suggests that microfibers at 20 mg/L insignificantly affected methane production in controlled anaerobic digestion. In contrast, ozone pretreatment of microfibers enhanced gas production by 12% in the same concentration level. Interestingly, ozone pretreatment at a higher concentration (100 mg/L–1000 mg/L) of microfibers did not affect methane production. SEM/EDX results imply that the ozone pretreatment has changed the surface characteristics of the microfibers, which provide more surface area for adsorption. The significant reduction of soluble phosphorus by 58% indicates that microfibers potentially act as a site for adsorption during anaerobic digestion. Overall, the presence of microfibers had a positive effect on anaerobic digestion. However, this work also indicated that the microfibers were not biodegraded during anaerobic digestion. Therefore, microfibers accumulate on biosolids, potentially affecting the final disposal of microfibers.

Research and characterization of fibrous microplastics and natural microfibers in pelagic and benthic fish species of commercial interest.

The ingestion of synthetic microfibers, the most prevalent type of microplastics in marine environments, and natural fibers was assessed in Engraulis engrasicolus and Mullus barbatus, two commercially important fish species in the Mediterranean Sea. Microfibers were isolated from the fish gastrointestinal tract using a 10% potassium hydroxide solution. For the microfiber characterization, the evaluation of specific morphological features using a light microscope, coupled with the Fourier-transform infrared (FTIR) analysis of a subsample of isolated particles, was applied. The preliminary results showed the occurrence of microfibers in 53 and 60% of European anchovy and Red mullet, respectively. A mean of 6.9 microfibers/individual was detected in anchovies, while on average Red mullet samples contained 9.2 microfibers/individual. The most common colors of fibers in both species were black, blue, and transparent. Visual characterization of fibers allowed the classification of 40% of the items as synthetic microfibers. FTIR spectroscopy confirmed the visual classification by fiber morphology. Microfibers were made of different typologies of polymers, represented by cellulose, cotton, and polyester. These findings confirm as the wide distribution of fibrous microplastics, and natural microfibers may impact both pelagic and deep-sea trophic webs. Despite the presence of microfibers in fish species poses a potential risk to human health, the literature is scarce regarding studies on the uptake by commercial marine fish mostly due to methodological issues. The visual characterization, corroborated by spectroscopic techniques, may be useful to differentiate synthetic and natural fibers, representing a fast and easy method to assess fibrous microplastic pollution in commercially important fish species.

Aerosol Filtration Performance of Solution Blown PA6 Webs with Bimodal Fiber Distribution.

A bimodal web, where both nanofibers and microfibers are present and distributed randomly across the same web, can deliver high filter efficiency and low pressure drop at the same time since in such a web, filter efficiency is high thanks to small pores created by the presence of nanofibers and the interfiber space created by the presence of microfibers, which is large enough for air to flow through with little resistance. In this work, a bimodal polyamide 6 (PA6) filter web was fabricated via a modified solution blowing (m-SB) technique that produced nanofibers and microfibers simultaneously. Scanning electron microscope (SEM) images of the webs were used to analyze the fiber morphology. Additionally, air permeability, solidity, porosity, filtration performance, and tensile strength of the samples were measured. The bimodal filter web consisted of nanofibers and microfibers with average diameters of 81.5 ± 127 nm and 1.6 ± 0.458 μm, respectively. Its filter efficiency, pressure drop at 95 L min-1, and tensile strength were 98.891%, 168 Pa, and 0.1 MPa, respectively. Its quality factor (QF) and tensile strength were 0.0268 Pa-1 and 0.1 MPa, respectively. When compared with commercially available filters, the bimodal web produced had superior filter performance, constituting a suitable alternative for air filter applications.