Search

Abstract We investigate the exclusive $$J/\psi $$ J / ψ production at the future Electron-ion collider in China by utilizing the eSTARlight event generator. We model the cross-section and kinematics by fitting to the world data of $$J/\psi $$ J / ψ photoproduction. Projected statistical uncertainties on $$J/\psi $$ J / ψ production are based on the design of a central detector, which consists of a tracker and vertex subsystem. The precision of the pseudo-data allows us to probe the near-threshold mechanism, e.g. the re-scattering effect. The significance of the forward amplitudes is discussed as well. The design and optimization of the detector enhance the potential for exploring the near-threshold region and the realm of high four-momentum transfer squared, which is of particular interest on several physics topics.

Abstract To explore the relationship between physical exercise and smoking behavior among Chinese residents aged 16 years and older. Analysis based on 29,466 validated cases in the 2018 China Family Panel Studies (CFPS 2018). The chi-square test and Mann–Whitney U test were used for comparative analysis between groups. Logistic regression analysis was used to explore the relationship between physical exercise and smoking behavior. Gender and birth cohort differences in the relationship between physical exercise and smoking behavior were explored based on stratified regression analysis using gender and birth cohort as stratified variables, respectively. Robustness testing based on multiple linear regression analysis using a replacement data approach. There were 8735 cases of smokers among the respondents. After controlling for relevant confounders, there was a significant negative association between physical exercise and smoking behavior among residents [OR 0.718, 95% CI (0.673, 0.765), P 0.05]. Physical exercise was more significantly associated with smoking behavior in the pre-1948 (OR 0.748), 1959–1968 (OR 0.748), 1969–1978 (OR 0.812), 1989–1998 (OR 0.576) and post-1999 (OR 0.411) birth cohorts, and the association decreased over time and with social change. The results of the robustness test showed that frequency of exercise was significantly and negatively associated with smoking behavior among residents [OR 0.961, 95% CI (0.951, 0.970), P

Conventional strategies for highly efficient and selective CO2 photoreduction focus on the design of catalysts and cocatalysts. In this study, we discover that hydrogen bond network breakdown in reaction system can suppress H2 evolution, thereby improving CO2 photoreduction performance. Photosensitive poly(ionic liquid)s are designed as photocatalysts owing to their strong hydrogen bonding with solvents. The hydrogen bond strength is tuned by solvent composition, thereby effectively regulating H2 evolution (from 0 to 12.6 mmol g−1 h−1). No H2 is detected after hydrogen bond network breakdown with trichloromethane or tetrachloromethane as additives. CO production rate and selectivity increase to 35.4 mmol g−1 h−1 and 98.9 % with trichloromethane, compared with 0.6 mmol g−1 h−1 and 26.2 %, respectively, without trichloromethane. Raman spectroscopy and theoretical calculations confirm that trichloromethane broke the systemic hydrogen bond network and subsequently suppressed H2 evolution. This hydrogen bond network breakdown strategy may be extended to other catalytic reactions involving H2 evolution. [ABSTRACT FROM AUTHOR]

It is a challenge to characterize the acid properties of microporous materials in either experiments or theory. This study presents the crystal structure, acid site, acid strength, proton siting, and IR spectra of HSAPO-34 from the SCAN + rVV10 method. The results indicate: the crystal structures of various acid sites of HSAPO-34 deviate from the space group of R 3 ¯ ; the acid strength inferred from the DPE value likely decreases with the proton binding sites at O(2), O(4), O(1),and O(3), contrary to the stability order in view of the internal energy; the calculated ensemble-averaged DPE is about 1525 kJ/mol at 673.15 K; and the proton siting and the proton distribution are distinctly influenced by the temperature: at low temperatures, the proton is predominantly located at O(3), while it prefers O(2) at high temperatures, and the proton at O(4) assumedly has the least distribution at 273.15–773.15 K. In line with the neutron diffraction experiment, a correction factor of 0.979 is needed to correct for the calculated hydroxyl stretching vibration (ν(O-H)) of HSAPO-34. It seems that the SCAN meta-GGA method, compensating for some drawbacks of the GGA method, could provide satisfying results regarding the acid properties of HSAPO-34. [ABSTRACT FROM AUTHOR]

Direct conversion of CO2 into pure formic acid (FA) solution in the absence of base additives is of great significance, but is challenging due to thermodynamic limitations. Here, we have synthesized ultrafine Pd nano-catalysts modified with three kinds of amine groups, including a primary amine (PA), secondary amine (SA) and tertiary amine (TA), which realized the efficient hydrogenation of CO2 to pure FA in water at room temperature for the first time. Comprehensive characterizations reveal that all the amine groups are beneficial to the formation of ultrafine and uniform Pd nanoclusters (<2 nm), and that the electron-richness of Pd has a competitive effect with the steric hindrance of the amine groups on the CO2 hydrogenation activity. The SA-modified catalyst Pd/AC-SA, which has a lower binding energy of N and lower steric hindrance, thus shows the best turnover frequency (TOF) of 29.1 h−1 at 298 K and 4.0 MPa, which is even comparable to that of reported heterogeneous catalysts with base additives under harsh conditions. The DFT calculations further revealed the mechanism of CO2 hydrogenation; the first H-atom hydrogenation is the rate-determining step, which is in good agreement with the experiments. This work, as a successful example of the direct generation of pure FA solution at room temperature, exhibits great potential for future large-scale hydrogen storage. [ABSTRACT FROM AUTHOR]