Carbon dioxide gasification characteristics of disposable COVID-19 masks using bubbling fluidized bed reactor.

The global demand for masks has increased significantly owing to COVID-19 and mutated viruses, resulting in a massive amount of mask waste of approximately 490,000 tons per month. Mask waste recycling is challenging because of the composition of multicomponent polymers and iron, which puts them at risk of viral infection. Conventional treatment methods also cause environmental pollution. Gasification is an effective method for processing multicomponent plastics and obtaining syngas for various applications. This study investigated the carbon dioxide gasification and tar removal characteristics of an activated carbon bed using a 1-kg/h laboratory-scale bubble fluidized bed gasifier. The syngas composition was analyzed as 10.52 vol% of hydrogen, 6.18 vol% of carbon monoxide, 12.05 vol% of methane, and 14.44 vol% of hydrocarbons (C2-C3). The results of carbon dioxide gasification with activated carbon showed a tar-reduction efficiency of 49%, carbon conversion efficiency of 45.16%, and cold gas efficiency of 88.92%. This study provides basic data on mask waste carbon dioxide gasification using greenhouse gases as useful product gases.

Hydrogen-rich gas production from disposable COVID-19 mask by steam gasification.

Globally, the demand for masks has increased due to the COVID-19 pandemic, resulting in 490,201 tons of waste masks disposed of per month. Since masks are used in places with a high risk of virus infection, waste masks retain the risk of virus contamination. In this study, a 1 kg/h lab-scale (diameter: 0.114 m, height: 1 m) bubbling fluidized bed gasifier was used for steam gasification (temperature: 800 °C, steam/carbon (S/C) ratio: 1.5) of waste masks. The use of a downstream reactor with activated carbon (AC) for tar cracking and the enhancement of hydrogen production was examined. Steam gasification with AC produces syngas with H2, CO, CH4, and CO2 content of 38.89, 6.40, 21.69, and 7.34 vol%, respectively. The lower heating value of the product gas was 29.66 MJ/Nm3 and the cold gas efficiency was 74.55 %. This study showed that steam gasification can be used for the utilization of waste masks and the production of hydrogen-rich gas for further applications.

Mutations in OsDET1, OsCOP10, and OsDDB1 confer embryonic lethality and alter flavonoid accumulation in Rice (Oryza sativa L.) seed.

Morphological and biochemical changes accompanying embryogenesis and seed development are crucial for plant survival and crop productivity. Here, we identified a novel yellowish-pericarp embryo lethal (yel) mutant of the japonica rice cultivar Sindongjin (Oryza sativa L.), namely, yel-sdj. Seeds of the yel-sdj mutant showed a yellowish pericarp and black embryo, and were embryonic lethal. Compared with wild-type seeds, the yel-sdj mutant seeds exhibited significantly reduced grain size, grain weight, and embryo weight, and a remarkably lower rate of embryo retention in kernels subjected to milling. However, the volume of air space between embryo and endosperm, density of embryo, and total phenolic content (TPC) and antioxidant activity of mature grains were significantly higher in the yel-sdj mutant than in the wild type. Genetic analysis and mapping revealed that the yel-sdj mutant was non-allelic to the oscop1 null mutants yel-hc, yel-cc, and yel-sk, and its phenotype was controlled by a single recessive gene, LOC_Os01g01484, an ortholog of Arabidopsis thaliana DE-ETIOLATED 1 (DET1). The yel-sdj mutant carried a 7 bp deletion in the second exon of OsDET1. Seeds of the osdet1 knockout mutant, generated via CRISPR/Cas9-based gene editing, displayed the yel mutant phenotype. Consistent with the fact that OsDET1 interacts with CONSTITUTIVE PHOTOMORPHOGENIC 10 (OsCOP10) and UV-DAMAGED DNA BINDING PROTEIN 1 (OsDDB1) to form the COP10-DET1-DDB1 (CDD), seeds of oscop10 and osddb1 knockout mutants also showed the yel phenotype. These findings will enhance our understanding of the functional roles of OsDET1 and the CDD complex in embryogenesis and flavonoid biosynthesis in rice seeds.

Effects of treatment with aqueous and acid-based coloring liquid on the color of zirconia.

STATEMENT OF PROBLEM: To preserve the mechanical property of color-treated zirconia for optimal restoration longevity, aqueous colorants have been developed as an alternative to acid-based coloring agents. However, little is known regarding the effects of aqueous colorants on the color of zirconia. PURPOSE: The purpose of this in vitro study was to compare the effect of aqueous coloring liquids with acid-based coloring liquids on the color of zirconia. MATERIAL AND METHODS: Eighty monolithic zirconia specimens (10×10×2 mm) were fabricated and divided into 4 groups according to their color treatment: unshaded zirconia (control), precolored zirconia, aqueous coloring liquid on zirconia, and acid-based coloring liquid on zirconia. The shaded zirconia specimens were further divided into 3 subgroups based on the number of coloring applications used (1, 3, or 6). The International Commission on Illumination (CIELab) color coordinates were measured by spectrophotometry. RESULTS: Significant differences in the CIE a∗ and b∗ values were observed between the specimen groups treated with the aqueous coloring liquid and the acid-based coloring liquid (P<.001). Increasing the number of colorings resulted in an increase in the CIE a∗ and b∗ values and a decrease in the CIE L∗ values in all the groups (P<.001). CONCLUSIONS: Treatment with aqueous coloring liquid on zirconia produced a greater redness or yellowness compared with treatment with acid-based coloring liquid. The coloring of zirconia lowered its brightness and imparted a red/yellow hue.

Effects of aqueous and acid-based coloring liquids on the hardness of zirconia restorations.

STATEMENT OF PROBLEM: The effects of the application of aqueous coloring liquids on the mechanical properties of zirconia have not yet been investigated. PURPOSE: The purpose of this in vitro study was to evaluate the effects of 3 different coloring techniques and the number of coloring liquid applications on the hardness of zirconia. MATERIAL AND METHODS: Eighty specimens were divided into 8 groups (n=10); nonshaded zirconia, preshaded zirconia, acid-based coloring liquid zirconia, and aqueous coloring liquid zirconia (1, 3, 6). Vickers hardness was measured. Data were analyzed via 1-way and 2-way ANOVAs. Multiple comparisons were performed using a Scheffé test (α=.05). RESULTS: Statistically significant differences in hardness were found between acid-based coloring liquid zirconia and aqueous coloring liquid zirconia (P<.001). Increasing the number of coloring liquid applications decreased the hardness value of acid-based coloring liquid zirconia (P<.001) but had no effect on the hardness of aqueous coloring liquid zirconia (P>.05). CONCLUSIONS: Within the limitations of this study, the hardness of zirconia was influenced to differing degrees depending on coloring technique. The number of coloring liquid applications affected the hardness of zirconia colored with the acid-based coloring liquid but not the hardness of zirconia colored with the aqueous coloring liquid.

Screening of herbal medicines for the recovery of cisplatin-induced nephrotoxicity.

The goal of this study was to quantitatively determine the recovery effects of herbal medicines (HM) on the cisplatin-induced nephrotoxicity. In the present study, the recovery effects of 239 HM on HEK 293 cells that had been damaged by cisplatin were evaluated by a mitochondrial activity MTS assay. After the first round of screening, candidate HM were selected based on a recovery rate of greater than 20%. The efficacy of the selected herbs was then determined by dose response kinetic analysis. Of the extracts evaluated, 7 HM (Paeonia suffruticosa (PS), Curcuma longa (CL), Centipeda minima (CM), Loranthus parasiticus (LP), Pulsatilla dahurica (PD), Sinapis alba (SA), and Scutellaria barbata (SB)) had a strong recovery effect on cisplatin-induced damage in HEK 293 cells. An LDH assay showed that LP, CM, SB, CL, SA, and PS had the best recovery effect, whereas a comet assay indicated that PS, SB, SA, PD, and CL had the best recovery effect. Taken together, these results suggest that SB, CL, PS, and SA are the best candidate HM for the recovery of cisplatin-induced nephrotoxicity. Therefore, additional studies should be conducted to determine if these HM possess novel therapeutic agents that can be used for the prevention or treatment of renal disorders.