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We report on a normal incidence grating spectrometer for angle-resolved inverse photoemission spectroscopy covering a photon energy range from 10 to 40 eV. Following diffraction from a spherical grating with 201.4 mm radius and 3600 lines/mm the photons are recorded by a position sensitive detector. The compact mounting of the grating and detector on a single 150 mm CF flange is established by displacing detector and sample from the Rowland circle. The performance of the spectrometer concerning energy calibration, spectral efficiency, optical resolution, and count rates was experimentally investigated and found to match the design goals well. Operated together with a low energy electron gun using a low temperature BaO cathode a typical total energy resolution of 360 meV at hν=15 eV is obtained in inverse photoemission spectroscopy. It is shown that due to its compactness the spectrometer unit can be effectively combined with other components for surface analysis.

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Objective: Outcomes after surgical aortic root replacement using different valved conduits are rarely reported. The present study shows the experience of a single center with the use of the partially biological LABCOR (LC) conduit and the fully biological BioIntegral (BI) conduit. Special attention was paid to preoperative endocarditis. Methods: All 266 patients who underwent aortic root replacement by an LC conduit (n = 193) or a BI conduit (n = 73) between 01/01/2014 and 31/12/2020 were studied retrospectively. Dependency on an extracorporeal life support system preoperatively and congenital heart disease were exclusion criteria. For patients with (n = 67) and without (n = 199) preoperative endocarditis subanalyses were made. Results: Patients treated with a BI conduit were more likely to have diabetes mellitus (21.9 vs. 6.7%, p < 0.001), previous cardiac surgery (86.3 vs. 16.6%; p < 0.001), permanent pacemaker (21.9 vs. 2.1%; p < 0.001), and had a higher EuroSCORE II (14.9 vs. 4.1%; p < 0.001). The BI conduit was used more frequently for prosthetic endocarditis (75.3 vs. 3.6%; <0.001), and the LC conduit was used predominantly for ascending aortic aneurysms (80.3 vs. 41.1%; <0.001) and Stanford type A aortic dissections (24.9 vs. 9.6%; p = 0.006). The LC conduit was used more often for elective (61.7 vs. 47.9%; p = 0.043) and emergency (27.5 vs. 15.1%; p = 0–035) surgeries, and the BI conduit for urgent surgeries (37.0 vs. 10.9%; p < 0.001). Conduit sizes did not differ significantly, with a median of 25 mm in each case. Surgical times were longer in the BI group. In the LC group, coronary artery bypass grafting and proximal or total replacement of the aortic arch were combined more frequently, whereas in the BI group, partial replacement of the aortic arch were combined. In the BI group, ICU length of stay and duration of ventilation were longer, and rates of tracheostomy and atrioventricular block, pacemaker dependence, dialysis, and 30-day mortality were higher. Atrial fibrillation occurred more frequently in the LC group. Follow-up time was longer and rates of stroke and cardiac death were less frequent in the LC group. Postoperative echocardiographic findings at follow-up were not significantly different between conduits. Survival of LC patients was better than that of BI patients. In the subanalysis of patients with preoperative endocarditis, significant differences between the used conduits were found with respect to previous cardiac surgery, EuroSCORE II, aortic valve and prosthesis endocarditis, elective operation, duration of operation, and proximal aortic arch replacement. For patients without preoperative endocarditis, significant differences were observed concerning previous cardiac surgery, pacemaker implantation history, duration of procedure, and bypass time. The Kaplan–Meier curves for the subanalyses showed no significant differences between the used conduits. Conclusions: Both biological conduits studied here are equally suitable in principle for complete replacement of the aortic root in all aortic root pathologies. The BI conduit is often used in bail-out situations, especially in severe endocarditis, without being able to show a clinical advantage over the LC conduit in this context.