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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 < 0.01]. Physical exercise was more significantly associated with smoking behavior among male residents [OR 0.694, 95% CI (0.649, 0.743), P < 0.01], while it was not significantly associated with smoking behavior among female residents [OR 0.901, 95% CI (0.743, 1.093), 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 < 0.01]. Physical exercise is negatively associated with smoking behavior among Chinese residents aged 16 years and older, especially among male residents. There is a cohort effect between physical exercise and smoking behavior of the population, that is, the relationship between the two decreases with social change. [ABSTRACT FROM AUTHOR]

Motifs of planar metalloborophenes, cage-like metalloborospherenes, and metal-centered double-ring tubular boron species have been reported. Based on extensive first-principles theory calculations, we present herein the possibility of doping the quasi-planar C2v B56 (A-1) with an alkaline-earth metal to produce the penta-ring tubular Ca©B56 (B-1) which is the most stable isomer of the system obtained and can be viewed as the embryo of metal-doped (4,0) boron α-nanotube Ca©BNT(4,0) (C-1). Ca©BNT(4,0) (C-1) can be constructed by rolling up the most stable boron α-sheet and is predicted to be metallic in nature. Detailed bonding analyses show that the highly stable planar C2v B56 (A-1) is the boron analog of circumbiphenyl (C38H16) in π-bonding, while the 3D aromatic C4v Ca©B56 (B-1) possesses a perfect delocalized π system over the σ-skeleton on the tube surface. The IR and Raman spectra of C4v Ca©B56 (B-1) and photoelectron spectrum of its monoanion C4v Ca©B56− are computationally simulated to facilitate their spectroscopic characterizations. [ABSTRACT FROM AUTHOR]

Because of its novel physical properties, two-dimensional materials have attracted great attention. From first-principle calculations and vibration frequencies analysis, we predict a new family of two-dimensional materials based on the idea of octet stability: honeycomb lattices of pnictogens (N, P, As, Sb, Bi). The buckled structures of materials come from the sp3 hybridization. These materials have indirect band gap ranging from 0.43 eV to 3.7 eV. From the analysis of projected density of states, we argue that the s and p orbitals together are sufficient to describe the electronic structure under tight-binding model, and the tight-binding parameters are obtained by fitting the band structures to first-principle results. Surprisingly large on-site spin-orbit coupling is found for all the pnictogen lattices except nitrogen. Investigation on the electronic structures of both zigzag and armchair nanoribbons reveals the possible existence of spin-polarized ferromagnetic edge states in some cases, which are rare in one-dimensional systems. These edge states and magnetism may exist under the condition of high vacuum and low temperature. This new family of materials would have promising applications in electronics, optics, sensors, and solar cells. [ABSTRACT FROM AUTHOR]