Observation of robust superlubricity of MoS₂ on Au(111) in ultrahigh vacuum

The structural and superlubric properties of single layer MoS2 on Au(1 1 1) forming moiré superlattice structures have been investigated by means of ultrahigh vacuum atomic force microscope with bimodal and contact modes. We synthesize epitaxial monolayer MoS2 flakes on the Au(1 1 1) surface in ultrahigh vacuum. Using friction force microscopy, atomic friction measurements indicate a superlubric regime between the tip apex and the moiré corrugated MoS2 surface in which the friction force remains at an ultralow value and is independent from normal load. Superlubricity conditions are observed for different loads and velocities which indicates the absence of out-of-plane deformations. We find that the MoS2 layer including the moiré superlattice modulation originating from the natural misfit between MoS2 and the Au(1 1 1) substrate is relatively rigid. We also demonstrate a low friction coefficient of the MoS2 surface crossing a single Au(1 1 1) step. Our results open up a new avenue for minimizing friction in nanoscale electronic devices and other dry rigid contacts used in aerospace lubrication

Immediate and long-term outcomes of percutaneous transcatheter pulmonary valve implantation

Background: Transcutaneous pulmonary valve replacement (TPVR) has become an alternative to heart surgery for patients after previous right ventricular outflow tract (RVOT) or pulmonary artery (PA) surgical interventions. The objective was to present immediate and long-term outcomes of trans¬cutaneous pulmonary valve replacement. Methods: Between 06/2009 and 06/2016, 46 patients underwent TPVR. Initial diagnoses included tetralogy of Fallot, common arterial trunk, transposition of great arteries post Rastelli correction, left ventricle outflow obstruction after Ross operation, pulmonary atresia, and isolated dysplastic pulmonary valve stenosis. Thirty eight (78%) patients had previously implanted conduits in the pulmonary position, the rest had either RVOT patch reconstruction (n = 6; 13%) or biological valve implantation (n = 2; 4%). They presented primarily with pulmonary stenosis (n = 18; 39%) or regurgitation (n = 28; 60%). Results: All procedures were successful — 44 Melody and 2 Edwards-Sapien valves were implanted. Before each procedure exclusion of potential coronary compression and RVOT prestenting was performed. Significant RVOT systolic gradient reduction (from 35.3 ± 19.5 to 13.5 ± 7.1 mm Hg; p < 0.001) and decrease of right to left ventricle systolic pressure ratio from 0.58 ± 0.18 to mean 0.37 ± 0.1 (p < 0.001) was achieved. Also, in every patient PA-RVOT competence was restored, with minor in¬competence in only a few patients. Post procedure follow-up ranged from 2 to 86 (mean 35.2) months. Follow-up fluoroscopy or chest X-ray revealed 6 stent fractures (2 stent defragmentation — with only 1 significant valve stenosis). Conclusions: Transcutaneous pulmonary valve replacement is a safe procedure with encouraging results, it also enables deferring surgical reintervention in the majority of patients

Comparison of reorganized versus unaltered cardiology departments during the COVID-19 era: a subanalysis of the COV-HF-SIRIO 6 study

Background: Since the beginning of the coronavirus disease-2019 (COVID-19) pandemic, numerous cardiology departments were reorganized to provide care for COVID-19 patients. We aimed to compare the impact of the COVID-19 pandemic on hospital admissions and in-hospital mortality in reorganized vs. unaltered cardiology departments. Methods: The present subanalysis is a multicenter retrospective COV-HF-SIRIO 6 study that includes all patients (n = 101,433) hospitalized in 24 cardiology departments in Poland between January 1, 2019 and December 31, 2020, with a focus on patients with acute heart failure (AHF). Results: Reduction of all-cause hospitalizations was 50.6% vs. 21.3% for reorganized vs. unaltered cardiology departments in 2020 vs. 2019, respectively (p &lt; 0.0001). Considering AHF alone respective reductions by 46.5% and 15.2% were registered (p &lt; 0.0001). A higher percentage of patients was brought in by ambulance to reorganized vs. unaltered cardiology departments (51.7% vs. 34.6%; p &lt; 0.0001) alongside with a lower rate of self-referrals (45.7% vs. 58.4%; p &lt; 0.0001). The rate of all-cause in-hospital mortality in AHF patients was higher in reorganized than unaltered cardiology departments (10.9% vs. 6.4%; p &lt; 0.0001). After the exclusion of patients with concomitant COVID-19, the mortality rates did not differ significantly (6.9% vs. 6.4%; p = 0.55). Conclusions: In cardiology departments reorganized to provide care for COVID-19 patients vs. unaltered ones, observed: i) a greater reduction in hospital admissions in 2020 vs. 2019; ii) higher rates of patients brought by ambulance and lower rates of self-referrals; and iii) higher all-cause in-hospital mortality for AHF due to COVID-19 related deaths