Ratoon Rice Cropping Mitigates the Greenhouse Effect by Reducing CH4 Emissions through Reduction of Biomass during the Ratoon Season.

The ratoon rice cropping system (RR) is developing rapidly in China due to its comparable annual yield and lower agricultural and labor inputs than the double rice cropping system (DR). Here, to further compare the greenhouse effects of RR and DR, a two-year field experiment was carried out in Hubei Province, central China. The ratoon season showed significantly lower cumulative CH4 emissions than the main season of RR, the early season and late season of DR. RR led to significantly lower annual cumulative CH4 emissions, but no significant difference in cumulative annual N2O emissions compared with DR. In RR, the main and ratoon seasons had significantly higher and lower grain yields than the early and late seasons of DR, respectively, resulting in comparable annual grain yields between the two systems. In addition, the ratoon season had significantly lower global warming potential (GWP) and greenhouse gas intensity-based grain yield (GHGI) than the main and late seasons. The annual GWP and GHGI of RR were significantly lower than those of DR. In general, the differences in annual CH4 emissions, GWP, and GHGI could be primarily attributed to the differences between the ratoon season and the late season. Moreover, GWP and GHGI exhibited significant positive correlations with cumulative emissions of CH4 rather than N2O. The leaf area index (LAI) and biomass accumulation in the ratoon season were significantly lower than those in the main season and late season, and CH4 emissions, GWP, and GHGI showed significant positive correlations with LAI, biomass accumulation and grain yield in the ratoon and late season. Finally, RR had significantly higher net ecosystem economic benefits (NEEB) than DR. Overall, this study indicates that RR is a green cropping system with lower annual CH4 emissions, GWP, and GHGI as well as higher NEEB.

N-Heterocyclic Nitrenium-Catalyzed Photohomolysis of CF3SO2Cl for Alkene Trifluoromethylation.

N-Heterocyclic nitreniums (NHNs) have been utilized as Lewis acid catalysts to activate substrates with lone pairs. Alternative to their conventional applications, we have discovered that NHNs can also serve as charge transfer complex catalysts. Herein, we present another potential of NHNs by utilizing a weak interaction between NHNs and CF3SO2Cl. The method promotes CF3SO2Cl to undergo photohomolysis, resulting in the CF3 radical. Mechanistic studies suggested that the weak interaction could be due to the π-hole effect of NHNs.

Association Between Perceived Levels of Stress and Self-Reported Food Preferences Among Males and Females: A Stated Preference Approach Based on the China Health and Nutrition Survey.

Objective: Stress is a major public health challenge and is associated with undesirable eating behavior. This cross-sectional study aimed to explore whether there is an association between perceived level of stress and food preference among Chinese adults. Study Design: Perceived level of stress was measured using the Chinese version of the 14-item Perceived Stress Scale, whereas self-reported food preferences were investigated by means of five food classification questions, including questions regarding the consumption of fast food, salty snacks, fruit, vegetables, and soft/sugary drinks. Methods: The data were collected from the 2015 China Health and Nutrition Survey. Information of 8,216 adults (≥18 years) on perceived level of stress, self-reported food preferences, and other important covariates was available and analyzed. Results: Perceived level of stress was negatively associated with a preference for fruit (ß = -0.58, 95% CI: -0.81 to -0.34, p < 0.0001) and vegetables (ß = -1.13, 95% CI: -1.41 to -0.85, p < 0.0001), while it was positively associated with a preference for fast food (ß = 0.36, 95% CI: 0.08-0.64, p = 0.011) and soft/sugary drinks (ß = 0.48, 95% CI: 0.30-0.66, p < 0.0001) after adjusting for potential confounders. No association between a preference for salty snacks and perceived level of stress was found in either men or women. Conclusions: The present population-based study reported strong associations between perceived level of stress and self-reported food preferences among Chinese adults. Sex differences related to this association were also worthy of attention.

Understanding the Chemoselectivity in Palladium-Catalyzed Three-Component Reaction of o-Bromobenzaldehyde, N-Tosylhydrazone, and Methanol.

To understand the ligand-controlled palladium-catalyzed coupling of o-bromobenzaldehyde, N-tosylhydrazone, and methanol to give methyl 2-benzylbenzoic ester or methyl ether, we herein investigated the mechanisms which account for how C-C and C-O bonds are formed and why bidentate dppf/dppb ligands afford ester, whereas P(o-tolyl)3 ligand gives ether. The ester chemoselectivity of the bidentate ligands is attributed to the strong electron-donating effect that disfavors the C,Br-reductive elimination of the coupling intermediate of o-bromobenzaldehyde and N-tosylhydrazone.

Density Functional Theory Mechanistic Study of Ni-Catalyzed Reductive Alkyne-Alkyne Cyclodimerization: Oxidative Cyclization versus Outer-Sphere Proton Transfer.

Density functional theory mechanistic study of the nickel-catalyzed reductive alkyne-alkyne cyclodimerization with CH3OH/BEt3 unveils that, after forming a nickel-alkyne π complex, the reaction prefers outer-sphere proton transfer rather than the common alkyne-alkyne oxidative cyclization. The outperformance of aminophosphine ligand (L1) is attributed to its bidentate coordination that favors the proton transfer, the labile -NH2 and strong electron-donating -PPh2 arms and adequate Ni-P distance that allow the hydrogen transfer of the ethyl group of MeO-BEt3-.

Palladium-Catalyzed Three-Component Coupling Reaction of o-Bromobenzaldehyde, N-Tosylhydrazone, and Methanol.

A ligand-controlled palladium-catalyzed three-component reaction of o-bromobenzaldehyde, N-tosylhydrazone, and methanol is described. This reaction uses readily available compounds as starting materials while displaying a broad substrate scope and good functional group compatibility.