Progress in Genotoxicity Evaluation of Engineered Nanomaterials

Engineered nanomaterials (ENMs) are being produced at an increasing rate. Because of their unique physicochemical properties, ENMs have been used in a wide variety of commercial products. The specific properties of ENMs, such as their relatively larger surface area, however, could also cause adverse biological effects different from their bulk counterparts. Nanomaterials can be genotoxic while their bulk counterparts are not, or vice versa, due to these specific characteristics. Also, the differences between nanomaterials and bulk materials can generate uncertainty when measuring the genotoxic potential of ENMs using current genotoxicity assays that were developed for conventional chemicals or bulk materials. In this chapter, we summarize current progress in evaluating the genotoxicity of ENMs with a focus on results from the standard genotoxicity assays, possible mechanisms underlying the genotoxicity of ENMs, the suitability of current genotoxicity assays for evaluation of ENMs, and application of ENM genotoxicity data for risk assessment. Future perspectives for the evaluation of ENM genotoxicity are also addressed

Free radical-scavenging activity and flavonoid contents of Polygonum orientale leaf, stem, and seed extracts

The present study was designed to explore the total flavonoid and taxifolin contents and the radical-scavenging activity of 50% ethanol extracts of Polygonum orientale leaves, stems, and seeds by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The extract with higher total flavonoid content has higher radical scavenging activity. Taxifolin (IC50 = 2.83 μmol/L) has antioxidant activity stronger than that of rutin (IC50 = 3.08 μmol/L). The free radical-scavenging potentials of chloroform, ethyl acetate, water, ethanol, and methanol extracts of Polygonum orientale seeds were also investigated. The free radical-scavenging abilities of various extracts were determined as: methanol > ethanol > water > ethyl acetate > chloroform

Error estimates of mixed finite element methods for quadratic optimal control problems

AbstractIn this paper, we investigate the error estimates for the solutions of optimal control problems by mixed finite element methods. The state and costate are approximated by Raviart–Thomas mixed finite element spaces of order k and the control is approximated by piecewise polynomials of order k. Under the special constraint set, we will show that the control variable can be smooth in the whole domain. We derive error estimates of optimal order both for the state variables and the control variable

Media tourism and COVID-19 : An empirical investigation of the impact of COVID-19 on the Scottish tourism industry

Peer reviewedPublisher PD