Investigation of Petroleum Coke Gasification with CO2/H2O Mixtures and S/N Removal Mechanism via ReaxFF MD Simulation.

The removal of environmentally harmful S/N is crucial for utilization of high-S petroleum coke (petcoke) as fuels. Gasification of petcoke enables enhanced desulfurization and denitrification efficiency. Herein, petcoke gasification with the mixture of two effective gasifiers (CO2 and H2O) was simulated via reactive force field molecular dynamics (ReaxFF MD). The synergistic effect of the mixed agents on gas production was revealed by altering the CO2/H2O ratio. It was determined that the rise in H2O content could boost gas yield and accelerate desulfurization. Gas productivity reached 65.6% when the CO2/H2O ratio was 3:7. During the gasification, pyrolysis occurred first to facilitate the decomposition of petcoke particles and S/N removal. Desulfurization with the CO2/H2O gas mixture could be expressed as thiophene-S → S → COS → CHOS, thiophene-S → S → HS → H2S. The N-containing components experienced complicated mutual reactions before being transferred into CON, H2N, HCN, and NO. Simulating the gasification process on a molecular level is helpful in capturing the detailed S/N conversion path and reaction mechanism.

Characterization of complete mitochondrial genome of the common tiger, Danaus genutia (Lepidoptera: Nymphalidae: Danainae) and phylogenetic implications within the subfamily Danainae.

Nymphalidae is the most diverse butterfly family worldwide, with more than 6000 species, whereas the mitogenomic data of nymphalid species, especially the subfamily Danainae, is still lacking for more comprehensive systematic studies. To this contribution, the complete mitogenome of Danaus genutia (Lepidoptera: Nymphalidae: Danainae) was determined via sequencing and annotating. The mitogenome in total consists of 15,255 base pairs (bp), containing 13 protein-coding genes, 22 transfer RNAs, 2 ribosomal RNAs, and a 440-bp noncoding A+T-rich region. Furthermore, phylogeny of the subfamily Danainae was reconstructed applying maximum likelihood and Bayesian inference on the basis of the mitogenomic data sets. Combined with our analysis and previous studies, the genus-level phylogenetic relationships within the subfamily Danainae are ((Tirumala + Danaus) + ((Idea + Euploea) + (Ideopsis + Parantica))). This study offers molecular information and provides a new perspective for phylogenetic research within the subfamily Danainae.

Bi-Functional Fe3 O4 /Au/CoFe-LDH Sandwich-Structured Electrocatalyst for Asymmetrical Electrolyzer with Low Operation Voltage.

The reduction of the overall electrolysis potential to produce hydrogen is a critical target for fabricating applicable hydrogen evolution cells. Sandwich-structured Fe3 O4 /Au/CoFe-LDH is synthesized via a spontaneous galvanic displacement reaction. A series of structural characterizations indicate the successful synthesis of sandwich-structured Fe3 O4 /Au/CoFe-LDH electrocatalyst. The trace amount of Au laying between Fe3 O4 and CoFe-LDH significantly improves the intrinsic conductivity and catalytic activity of the composite catalyst. In-depth investigations indicate that Fe3 O4 and CoFe-LDH are responsible for the electrocatalytic hydrogen evolution reaction (HER) whereas Au is responsible for the electrocatalytic glucose oxidation (GOR). The electrocatalytic tests indicate Fe3 O4 /Au/CoFe-LDH offers excellent electrocatalytic activity and stability for both HER and GOR, even at high current density (i.e., 1000 mA cm-2 ). Further electrochemistry examinations in a two-compartment cell with a two-electrode configuration show that Fe3 O4 /Au/CoFe-LDH can significantly reduce the overall potential for this asymmetrical cell, with only 0.48 and 0.89 V required to achieve 10 mA cm-2 current density with and without iR-compensation, which is the lowest overall potential requirement ever reported. The design and synthesis of Fe3 O4 /Au/CoFe-LDH pave a new way to electrochemically produce hydrogen and gluconate under extremely low cell voltage, which can readily match with a variety of solar cells.

Electrogenerated chemiluminescence of CdSe quantum dots dispersed in aqueous solution.

Electrogenerated chemiluminescence (ECL) of CdSe quantum dots (QDs) dispersed in aqueous solution was studied with bare electrode. The ECL emission was observed at -1.4 V vs. Ag/AgCl and the ECL spectrum peak is similar to that of the defect photoluminescence (PL) spectrum, indicating the surface defects played a critical role in the emission process. The experiment results suggested that dissolved oxygen had a great effect on the ECL intensity. Other influence factors including the electrochemical parameters and QDs concentration were investigated in detail. As an application of the CdSe QDs ECL, the pyrogallol (1, 2, 3-trihydroxybenzene) was detected in aqueous solution. Under the optimal conditions, a linear relationship between ECL intensity and pyrogallol concentration was obtained in the range from 4.0 x 10(-7) to 2.0 x 10(-5) M with a correlation coefficient of 0.9904 and the limit of detection was 6.6 x 10(-8) M (S/N = 3). A possible mechanism about ECL of QDs was also discussed.