Nexus of COVID-19 and carbon prices in the EU emission trading system: evidence from multifractal and the wavelet coherence approaches.

In this paper, we analyzed the role of carbon pricing as a vital tool for achieving the sustainable energy transition and discussed policy implications for reaching this goal in the era of the COVID-19 pandemic. To investigate the connection and cross-correlation between COVID-19 cases and carbon price returns in EU ETS, we applied two novel approaches: the multifractal detrending moving average cross-correlation (MF-X-DMA) and the wavelet coherence techniques. The coverage of data is from 2 March 2020 to 19 March 2021. The results of the MF-X-DMA method show that the cross-correlation is substantial and negatively correlated. Moreover, the results imply the presence of multifractal cross-correlations and that a significant change in the number of COVID-19 cases further impacts carbon price fluctuations. Concerning the wavelet coherence method results, we can also find a strong (negative) relationship between selected variables, and this strong correlation is observed throughout the whole study period. In addition, we observe that in the first wave of the COVID-19 outbreak, the changes in the COVID-19 cases are leading the CO2 price returns (particularly in the 16-32 time scale). The results of this study can have significant implications for policymakers and contributions for environmental experts and investors.

Synthesis of cellulose acetate/chitosan/SWCNT/Fe3O4/TiO2 composite nanofibers for the removal of Cr(VI), As(V), Methylene blue and Congo red from aqueous solutions.

The potential of electrospun cellulose acetate/chitosan/single walled carbon nanotubes/ferrite/titanium dioxide (CA/chitosan/SWCNT/Fe3O4/TiO2) nanofibers was investigated for the removal of Cr(VI), As(V), Methylene blue and Congo red from aqueous solutions via the adsorption and photocatalytic reduction processes. The properties of synthesized SWCNT/Fe3O4/TiO2 and fibers were characterized using TEM, SEM, FTIR, XRD, TGA and BET analysis. In adsorption process, the influence of adsorbent type including SWCNT to Fe3O4 ratio, TiO2 to SWCNT/Fe3O4 ratio and SWCNT/Fe3O4/TiO2 concentration as well as the adsorption parameters including pH, contact time, and initial concentration of adsorbates on the Cr(VI), As(V), Methylene blue and Congo red adsorption in a batch mode was investigated. The reusability of nanofibers was also investigated for five adsorption-desorption cycles. The photocatalytic reduction of Cr(VI), As(V), Methylene blue and Congo red was also investigated using various nanofibrous catalysts. The obtained results indicated that the removal of Cr(VI) and As(V) using CA/chitosan/SWCNT/Fe3O4/TiO2 nanofibrous adsorbent via adsorption process could be preferred for the lower concentrations of metal ions. The photocatalytic reduction was an effective method for the Cr(VI), As(V) removal at higher concentrations and degradation of Methylene blue and Congo red under both lower and higher concentrations of azo dyes.

Repair or replacement of amalgam restorations: decisions at a USA and a UK dental school.

Whereas replacement of failed restorations is the major treatment for adults in dental practice, repair is an important alternative with the potential to save tooth structure and increase the longevity of restorations at a lower cost. This in vitro study recorded the choices of treatment for the same set of teeth with defective Class II amalgam restorations by students and faculty at two dental schools (University of Manchester, UK and University of Florida, USA). Treatment options (monitor, refurbish, repair and replace) and reason(s) for the choice of treatment for 24 marked amalgam restorations were selected. Overall, participants more frequently chose replacement of restorations; whereas, repair was the least favored option. The reasons cited the most to replace restorations were secondary caries including unsightly appearance, partially lost restoration and tooth fracture; for repair, the major reasons included loss of part of the restoration and marginal ditching; and for refurbishment, the major reasons included poor anatomic form and marginal ditching. There was a significant difference between the students and faculties at the two sites in their choice of treatment (p<0.0001; Chi-square test). The treatment decision to "monitor" the restorations was more frequent for the Manchester site than the Florida site. Conversely, the combined treatment decisions to "refurbish, repair and replace" were more frequently chosen in Florida than in Manchester.