Ytterbia – praseodymia co-stabilized TZP with high toughness and transformation limited strength

Tetragonal zirconia polycrystals (TZP) with high strength and toughness offer the potential to compensate for manufacturing or application related defects. In this study aiming at ultimate toughness a co-stabilized TZP was manufactured by coating of monoclinic zirconia by a wet chemical process with 1.5 mol% ytterbia and 1.5 mol% praseodymia. The powder was hot-pressed at 1300–1400 °C in 25 °C increments for 1 h by 60 MPa axial pressure. The materials exhibit an ultrafine microstructure with grain sizes ranging from 130 to 200 nm. Mechanical properties were measured in a 3-point bending setup, the material shows a combination of moderate strength (600–950 MPa) and high toughness (11–12 MPa√m). Non-linear stress strain curves and occurrence of transformation bands prior to fracture indicate transformation induced failure behaviour. The transformation stress determined from the location of transformation bands in fractured samples increases with rising sintering temperature and is about 100–250 MPa lower than the bending strength

Mechanical properties and low temperature degradation of 1.5Y-1.5Nd-TZP-alumina composites produced by intensive co-milling

In this study toughness of alumina toughened zirconia (ATZ) was improved by co-stabilization by shifting from co-precipitated yttria stabilized zirconia powder to yttria neodymia co-stabilized starting powders in which the stabilizers were introduced by intensive milling. Alumina contents were varied between 0.5 and 20 ​vol.-%. Test samples were consolidated by hot pressing.Microstructure, phase composition, mechanical properties and LTD were studied. The results show that alumina addition leads to an increase in hardness and to a moderate increase in strength. Decreasing toughness with increasing alumina content is coupled with reduction in transformability. Alumina shows no grain growth inhibiting effect, the grain size is dominated by sintering temperature. An increase of sintering temperature causes a decrease of tetragonality of the zirconia matrix despite a rise of cubic phase content. Samples sintered at 1300 ​°C and 1350 ​°C are extremely ageing resistant while samples sintered at 1400 ​°C irrespective of alumina content exhibit poor LTD performance

Validating Discriminative Signatures for Obstructive Sleep Apnea in Exhaled Breath

Rapid and reliable tools for the diagnosis and monitoring of obstructive sleep apnea (OSA) are currently lacking. Prior studies using a chemical analysis of exhaled breath have suggested the existence of an OSA-specific metabolic signature. Here, we validated this diagnostic approach and the proposed marker compounds, as well as their potential to reliably diagnose OSA. In this cross-sectional observational study, exhaled breath was analyzed using secondary electrospray ionization high-resolution mass spectrometry. The study cohort included untreated OSA patients, OSA patients treated with continuous positive airway pressure and healthy subjects. The robustness of previously reported OSA markers was validated based on detectability, significant differences between groups (Mann-Whitney U test) and classification performance. The breath analysis of 118 participants resulted in 42 previously reported markers that could be confirmed in this independent validation cohort. Nine markers were significantly increased in untreated OSA compared to treated OSA, with a subset of them being consistent with a previous validation study. An OSA prediction based on the confirmed OSA signature performed with an AUC of 0.80 (accuracy 77%, sensitivity 73% and specificity 80%). As several breath markers were clearly found to be repeatable and robust in this independent validation study, these results underscore the clinical potential of breath analysis for OSA diagnostics and monitoring.ISSN:2073-440

Effect of a Strategy of Comprehensive Vasodilation vs Usual Care on Mortality and Heart Failure Rehospitalization Among Patients With Acute Heart Failure: The GALACTIC Randomized Clinical Trial

Short-term infusions of single vasodilators, usually given in a fixed dose, have not improved outcomes in patients with acute heart failure (AHF).; To evaluate the effect of a strategy that emphasized early intensive and sustained vasodilation using individualized up-titrated doses of established vasodilators in patients with AHF.; Randomized, open-label blinded-end-point trial enrolling 788 patients hospitalized for AHF with dyspnea, increased plasma concentrations of natriuretic peptides, systolic blood pressure of at least 100 mm Hg, and plan for treatment in a general ward in 10 tertiary and secondary hospitals in Switzerland, Bulgaria, Germany, Brazil, and Spain. Enrollment began in December 2007 and follow-up was completed in February 2019.; Patients were randomized 1:1 to a strategy of early intensive and sustained vasodilation throughout the hospitalization (n = 386) or usual care (n = 402). Early intensive and sustained vasodilation was a comprehensive pragmatic approach of maximal and sustained vasodilation combining individualized doses of sublingual and transdermal nitrates, low-dose oral hydralazine for 48 hours, and rapid up-titration of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, or sacubitril-valsartan.; The primary end point was a composite of all-cause mortality or rehospitalization for AHF at 180 days.; Among 788 patients randomized, 781 (99.1%; median age, 78 years; 36.9% women) completed the trial and were eligible for primary end point analysis. Follow-up at 180 days was completed for 779 patients (99.7%). The primary end point, a composite of all-cause mortality or rehospitalization for AHF at 180 days, occurred in 117 patients (30.6%) in the intervention group (including 55 deaths [14.4%]) and in 111 patients (27.8%) in the usual care group (including 61 deaths [15.3%]) (absolute difference for the primary end point, 2.8% [95% CI, -3.7% to 9.3%]; adjusted hazard ratio, 1.07 [95% CI, 0.83-1.39]; P = .59). The most common clinically significant adverse events with early intensive and sustained vasodilation vs usual care were hypokalemia (23% vs 25%), worsening renal function (21% vs 20%), headache (26% vs 10%), dizziness (15% vs 10%), and hypotension (8% vs 2%).; Among patients with AHF, a strategy of early intensive and sustained vasodilation, compared with usual care, did not significantly improve a composite outcome of all-cause mortality and AHF rehospitalization at 180 days.; ClinicalTrials.gov Identifier: NCT00512759