High Density Single Fe Atoms on Mesoporous N-Doped Carbons: Noble Metal-Free Electrocatalysts for Oxygen Reduction Reaction in Acidic and Alkaline Media.

It remains a challenge to develop efficient noble metal-free electrocatalysts for the oxygen reduction reaction (ORR) in various renewable energy systems. Single atom catalysts have recently drawn great attention as promising candidates both due to their high activity and their utmost atom utilization for electrocatalytic ORR. Herein, the synthesis of an efficient ORR electrocatalyst that is composed of N-doped mesoporous carbon and a high density (4.05 wt%) of single Fe atoms via pyrolysis Fe-conjugated polymer is reported. Benefiting from the abundant atomic Fe-N4 sites on its conductive, mesoporous carbon structures, this material exhibits an excellent electrocatalytic activity for ORR, with positive onset potentials of 0.93 and 0.98 V in acidic and alkaline media, respectively. Its electrocatalytic performance for ORR is also comparable to that of Pt/C (20 wt%) in both media. Furthermore, it electrocatalyzes the reaction almost fully to H2 O (or barely to H2 O2 ). Additionally, it is durable and tolerates the methanol crossover reaction well. Furthermore, a proton exchange membrane fuel cell and a zinc-air battery assembled using it on their cathode deliver high maximum power densities (320 and 91 mW cm-2 , respectively). Density functional theory calculation reveals that the material's decent electrocatalytic performance for ORR is due to its atomically dispersed Fe-N4 sites.

Structural Diversity of Six Coordination Polymers Based on the Designed X-Shaped Ligand 1,1,1,1-Tetrakis[(3-pyridiniourea)methyl]methane.

In this study, six coordination polymers (CPs), {[Ag2(L)(CF3SO3)]·CF3SO3·2H2O·DMF}n (1), {[Ag(L)]·SbF6·4DMF·H2O}n (2), {[Zn(L)0.5(I)2]·3.75H2O}n (3), {[Cd2(L)(I)4(H2O)(DMF)]·4H2O·3DMF}n (4), {[Hg2(L)(I)4]·H2O·4DMF}n (5) and {[Hg2(L)(Cl)4]·2H2O·3DMF}n (6), were obtained based on the designed X-shaped urea-based ligand. X-ray single crystal diffraction analysis revealed that complex 1 displayed a 3D (3,4)-connected {6·8²}{64·8²}-tcj net. Complex 2 featured a 2D 4-connected {4³·6³} sheet. Complexes 3 and 5 exhibited a 1D polymeric loop chain. Complex 4 displayed a 1D polymeric fishbone chain. Complex 6 showed a 2D 4-connected {44·6²}-sql sheet. Structural comparison revealed that not only the metal ions, but also the anions played crucial roles in the control of final structures.

Drug-coated balloon angioplasty versus drug-eluting stent implantation in ACS patients with different angiographic patterns of in-stent restenosis.

BACKGROUND: Drug-coated balloon (DCB) angioplasty and drug-eluting stents (DES) are two widely used treatments for in-stent restenosis (ISR). Focal and non-focal types of ISR affect the clinical outcomes. The present study aims to compare DES reimplantation versus DCB angioplasty in acute coronary syndrome (ACS) patients with focal ISR and non-focal ISR lesions. METHODS: Patients with ISR lesions underwent percutaneous coronary intervention (PCI) were retrospectively evaluated and divided into DES group and DCB group. The primary endpoint was the incidence of target lesion failure (TLF) at 24 months follow up. Propensity score matching (PSM) was conducted to balance the baseline characteristics. RESULTS: For focal ISR, TLF was comparable in the DES and DCB groups at 24 months of follow-up (Before PSM, hazard ratio [HR]: 0.70; 95% confidence interval [CI]: 0.39-1.27; p = 0.244; After PSM, HR: 0.83; 95% CI: 0.40-1.73; p = 0.625). For non-focal ISR, TLF was significantly decreased in DES compared with DCB group (Before PSM, HR: 0.43; 95% CI: 0.29-0.63; p < 0.001; After PSM, HR: 0.33; 95% CI: 0.19-0.59; p < 0.001), which was mainly attributed to the lower incidence of clinically indicated target lesion revascularization (CD-TLR) (Before PSM, HR: 0.39; 95% CI: 0.26-0.59; p < 0.001; After PSM, HR: 0.28; 95% CI: 0.15-0.54; p < 0.001). CONCLUSIONS: The clinical outcomes for DES and DCB treatment are similar in focal type of ISR lesions. For non-focal ISR, the treatment of DES showed a significant decrease in TLF which was mainly attributed to a lower incidence of CD-TLR.