26 research outputs found
Effect of the crystallographic c-axis orientation on the tribological properties of the few-layer PtSe2
Two-dimensional (2D) transition metal dichalcogenides are potential
candidates for ultrathin solid-state lubricants in low-dimensional systems
owing to their flatness, high in-plane mechanical strength, and low shear
interlayer strength. Yet, the effects of surface topography and surface
chemistry on the tribological properties of 2D layers are still unclear. In
this work, we performed a comparative investigation of nanoscale tribological
properties of ultra-thin highly-ordered PtSe2 layers deposited on the sapphire
substrates with the in-plane and out-of-plane crystallographic orientation of
the PtSe2 c-axis flakes, and epitaxial PtSe2 layers. PtSe2 c-axis orientation
was found to has an impact on the nanotribological, morphological and
electrical properties of PtSe2, in particular the change in the alignment of
the PtSe2 flakes from vertical (VA) to horizontal (HA) led to the lowering of
the coefficient of friction from 0.21 to 0.16. This observation was accompanied
by an increase in the root-mean-square surface roughness from 1.0 to 1.7 nm for
the HA and VA films, respectively. The epitaxial films showed lower friction
caused by lowering adhesion when compared to other investigated films, whereas
the friction coefficient was similar to films with HA flakes. The observed
trends in nanoscale friction is attributed to a different distribution of PtSe2
structure
Indications, complications, and outcomes of cardiac surgery after heart transplantation: results from the cash study
[Abstract] Background: Allograft pathologies, such as valvular, coronary artery, or aortic disease, may occur early and late after cardiac transplantation. Cardiac surgery after heart transplantation (CASH) may be an option to improve quality of life and allograft function and prolong survival. Experience with CASH, however, has been limited to single-center reports.
Methods: We performed a retrospective, multicenter study of heart transplant recipients with CASH between January 1984 and December 2020. In this study, 60 high-volume cardiac transplant centers were invited to participate.
Results: Data were available from 19 centers in North America (n = 7), South America (n = 1), and Europe (n = 11), with a total of 110 patients. A median of 3 (IQR 2-8.5) operations was reported by each center; five centers included ≥ 10 patients. Indications for CASH were valvular disease (n = 62), coronary artery disease (CAD) (n = 16), constrictive pericarditis (n = 17), aortic pathology (n = 13), and myxoma (n = 2). The median age at CASH was 57.7 (47.8-63.1) years, with a median time from transplant to CASH of 4.4 (1-9.6) years. Reoperation within the first year after transplantation was performed in 24.5%. In-hospital mortality was 9.1% (n = 10). 1-year survival was 86.2% and median follow-up was 8.2 (3.8-14.6) years. The most frequent perioperative complications were acute kidney injury and bleeding revision in 18 and 9.1%, respectively.
Conclusion: Cardiac surgery after heart transplantation has low in-hospital mortality and postoperative complications in carefully selected patients. The incidence and type of CASH vary between international centers. Risk factors for the worse outcome are higher European System for Cardiac Operative Risk Evaluation (EuroSCORE II) and postoperative renal failure
The European Registry for Patients with Mechanical Circulatory Support of the European Association for Cardio-Thoracic Surgery:third report
OBJECTIVES: In the third report of the European Registry for Patients with Mechanical Circulatory Support of the European Association for Cardio-Thoracic Surgery, outcomes of patients receiving mechanical circulatory support are reviewed in relation to implant era. METHODS: Procedures in adult patients (January 2011-June 2020) were included. Patients from centres with 3 months). Risk factors for death were explored using univariable Cox regression with a stepwise time-varying hazard ratio (3 months). RESULTS: In total, 4834 procedures in 4486 individual patients (72 hospitals) were included, with a median follow-up of 1.1 (interquartile range: 0.3-2.6) years. The annual number of implants (range: 346-600) did not significantly change (P = 0.41). Both Interagency Registry for Mechanically Assisted Circulatory Support class (classes 4-7: 23, 25 and 33%; P 3 months: 0.45). Bilirubin and creatinine levels were significant risk factors in the early phase but not in the late phase after the implant. CONCLUSIONS: In its 10 years of existence, EUROMACS has become a point of reference enabling benchmarking and outcome monitoring. Patient characteristics and outcomes changed between implant eras. In addition, both occurrence of outcomes and risk factor weights are time dependent
Bentall operation in a patient with an anomalous left circumflex artery: Case report and review
Anomalous origin of a left circumflex artery from the right coronary sinus represents a technical challenge in patients who require aortic valve/root procedures. This case report describes a patient who presented with bicuspid aortic valve, anomalous origin of the circumflex artery, severe aortic regurgitation, and aneurysm of the ascending aorta as well as aortic root that was safely managed following the Bentall procedure with the combined button technique