No abstract

The Lewis acidic sites and reducing power of a photocatalyst are critical for its performance in CO2 activation for cycloadditions. In this study, we designed and synthesized a Ti18Bi4O29Bz26 (Bz = benzoate) cluster molecule that contains Lewis acidic sites on the surface and combines Ti18O22 and Bi4O7 cluster counterparts. DFT calculations combined with synchronous illumination X-ray photoelectron spectroscopy reveal that the Ti18O22 and Bi4O7 components form an S-scheme heterojunction, significantly increasing the reducing power of photogenerated electrons and spatial separation of photogenerated charges. While Ti18Bi4O29Bz26 has some catalytic activity in the cycloaddition reaction between CO2 and epoxides at room temperature, light irradiation significantly increases both the conversion rate and the selectivity of the cyclocarbonate product. Mechanistic studies show that both electrons and holes contribute to the improved performance when exposed to light, and that the increased reducing power overcomes the cycloaddition reaction’s limiting stepCO2 reductive activation. This is not only the report on photocatalytic cycloaddition of CO2 using a Lewis acidic titanium-oxide cluster but also the example of the molecular S-scheme heterojunction to the best of our knowledge.

No abstract

No abstract

No abstract

No abstract

We considered the fully overlapping triplets of nucleotide bases and proposed a 2D graphical representation of protein sequences consisting of 20 amino acids and a stop code. Based on this 2D graphical representation, we outlined a new approach to analyze the phylogenetic relationships of coronaviruses by constructing a covariance matrix. The evolutionary distances are obtained through measuring the differences among the two-dimensional curves.

Grazing removal is widely used in grassland management. Plant responses following grazing removal at different organizational levels, however, are not well understood. We examined plant responses at different stocking rates in an Inner Mongolia grassland ecosystem dominated by Leymus chinensis and Stipa grandis. Our results indicated that plant response patterns differed significantly among stocking rates, at different levels of organization, and between wet and dry years. Community aboveground net primary production (ANPP) recovered more quickly at low and moderate stocking rates than those at high stocking rates. Response of aboveground net primary production (R ANPP ) was significantly positively correlated with both individual biomass and density responses of L. chinensis. Overcompensation of L. chinensis after grazing removal contributed greatly to positive R ANPP at the community level. Significant compensatory effects were found between the two dominant species and between dominant species and the remaining non-dominant species. Variation in precipitation significantly affected community ANPP, relationships between community and species responses, and compensatory effects between species. Our study suggests that periodic grazing removal is likely to be a useful method for grassland management and that a combination of species with compensatory effects can be advantageous for reseeding practices in grassland restoration.