Kinetic Investigation of Polyurethane Rubber Formation from CO2‐Containing Polyols

A novel CO2 utilization technology allows for the inclusion of CO2 as carbonate units and double bond moieties to give additional functionality in polyether polyols. This study examines the chain‐elongation kinetics of these diols with diisocyanates to polyurethane rubbers by means of thermal analysis. A reaction order of 1 indicates a strong influence of the chains' mobility on the reaction rate. Spectrometry and comparison with non‐double‐bond polyols reveal that the effect cannot be attributed to a substantial occurrence of side reactions but is rather due to the intertwining of lengthy chains.BMBF, 033R350A‐D, Production DreamsTU Berlin, Open-Access-Mittel - 202

Evaluation der hämodynamischen Eigenschaften von Aortenklappenprothesen und Vergleich zwischen Echokardiographie und invasiver Druckmessung in der Beurteilung von Aortenklappenprothesen

Die vorliegende Arbeit gliedert sich in zwei Teile: 1. Intraoperativer und postoperativer Vergleich der hämodynamischen Eigenschaften verschiedener Aortenklappenprothesen, ins besondere der St. Jude MedicalÒ RegentÔ-Prothese; 2. Intraoperativer Vergleich der Methoden der direkten Druckgradientenbestimmung und der Dopplergradientenbestimmung. Intraoperativ Messung des transvalvulären Druckgradienten mittels wassergefüllter Katheter und transösophagealer Echokardiographie, weiterhin Berechnung der Klappenöffnungsfläche nach der Gorlin-Formel und der Kontinuitätsgleichung. Es ergab sich sowohl intra- als auch postoperativ eine tendenzielle Überlegenheit der St. Jude MedicalÒ RegentÔ-Prothese gegen über den anderen untersuchten Modellen. Die Druckgradienten der beiden Methoden zeigten eine gute Übereinstimmung, was für die Klappenöffnungsflächen nicht gezeigt werden konnte. Als Ursache für die Überlegenheit der St. Jude MedicalÒ RegentÔ-Prothese ist vermutlich der größere Innendurchmesser dieses Modells anzusehen. Die schlechte Übereinstimmung der beiden Methoden bei den Klappenöffnungsflächen erklärt sich vermutlich dadurch, dass Klappenprothesen kein homogenes Geschwindigkeitsprofil zeigen, welches als Voraussetzung für die Berechnung der Kontinuitätsgleichung angesehen werden muss

Application of multivariate Tromp functions for evaluating the joint impact of particle size, shape and wettability on the separation of ultrafine particles via flotation

Froth flotation predominantly separates particles according to their differences in wettability. However, other particle properties such as size, shape or density significantly influence the separation outcome as well. Froth flotation is most efficient for particles within a size range of about $20-200\mu m$, but challenges arise for very fine or coarse particles that are accompanied by low recoveries and poor selectivity. While the impact of particle size on the separation behavior in flotation is well-known by now, the effect of particle shape is less studied and varies based on the investigated zone (suspension or froth) and the separation apparatus used. A multidimensional perspective on the separation process, considering multiple particle properties, enhances the understanding of their collective influence. In this paper the two-dimensional case is studied, i.e., a parametric modeling approach is applied to determine bivariate Tromp functions from scanning electron microscopy-based image data of the feed and the separated fractions. With these functions it is possible to characterize the separation behavior of particle systems. Using a model system of ultrafine ($<10\mu m$) particles, consisting of differently shaped glass particles with different wettability states as the floatable and magnetite as the non-floatable fraction, allows for investigating the influence of particle size, shape and wettability, on the separation. In this way, the present paper contributes to a better understanding of the complex interplay between certain property vectors for the case of ultrafine particles. Furthermore, it demonstrates the benefits of using multivariate Tromp functions for evaluating separation processes, and points out the limitations of SEM based image measurements by means of mineral liberation analysis (MLA) for the studied particle size fraction

Investigating the influence of particle size and shape on froth flotation based benefication of lithium-rich minerals in slags

The demand for lithium, as well as other critical resources, needed for electrochemical energy storage is expected to grow significantly in the future. Slags obtained from pyrometallurgical recycling represent a promising resource of valuable materials, among them lithium and rare earth elements found in artificial minerals particulate phases. This study investigates the flotation separation of engineered artificial minerals (EnAMs) in slags, such as lithium aluminate and gehlenite as valuable and gangue phases, respectively. Flotation experiments are carried out in a Partridge-Smith cell using oleic acid (OA) as a benchmark surfactant. Particle characterization is performed using SEM-based Mineral Liberation Analysis (MLA), which provides particle discrete information. From this information, bivariate Tromp functions based on non-parametric kernel density estimation are computed to characterize the separation behavior with respect to particle descriptors. This approach enables investigating the influence of particle size and shape on separation behavior of EnAMs. Furthermore, these results allow for the optimization of flotation experiments for enriching Li-bearing EnAMs

Safety and Efficiency of Rotational Atherectomy in Chronic Total Coronary Occlusion-One-Year Clinical Outcomes of an Observational Registry.

The study sought to assess the procedural success of rotational atherectomy (RA) in coronary chronic total occlusion (CTO) and to investigate the in-hospital and one-year outcomes following RA. From 2015 to 2019, patients undergoing percutaneous coronary intervention for CTO (CTO PCI) were retrospectively included into the hospital database. The primary endpoint was procedural success. Secondary endpoints were in-hospital and one-year major adverse cardiovascular and cerebral event (MACCE) rates. During the study period of 5 years, 2.789 patients underwent CTO PCI. Patients treated with RA (n = 193, 6.92%) had a significantly higher procedural success (93.26% vs. 85.10%, p = 0.0002) compared to those treated without RA (n = 2.596, 93.08%). Despite a significantly higher rate of pericardiocentesis (3.11% vs. 0.50%, p = 0.0013) in the RA group, the in-hospital and one-year MACCE rate was similar in both groups (4.15% vs. 2.77%, p = 0.2612; 18.65% vs. 16.72%, p = 0.485). In conclusion, RA is associated with higher procedural success for CTO PCI, but has higher risks for pericardial tamponade than CTO PCI without the need for RA. Nevertheless, in-hospital and one-year MACCE rates did not differ in-between both groups

A heart team’s perspective on interventional mitral valve repair: Percutaneous clip implantation as an important adjunct to a surgical mitral valve program for treatment of high-risk patients

ObjectiveSurgical mitral valve repair carries an elevated perioperative risk in the presence of severely reduced ventricular function and relevant comorbidities. We sought to assess the feasibility of catheter-based mitral valve repair using a clip-based percutaneous edge-to-edge repair system in selected patients at high surgical risk with mitral regurgitation grade 3 or worse.MethodsBetween 2002 and January 2011, 202 consecutive patients without prior mitral valve surgery (age 75 ± 9 years; 63% were male) with symptomatic functional (65%), degenerative (27%), or mixed (8%) mitral regurgitation were treated with a percutaneous clip system for approximation of the anterior and posterior mitral leaflets. Risk for mitral valve surgery was considered high in terms of a mean logistic European System for Cardiac Operative Risk Evaluation of 44% (range, 21%–54%). Preprocedural left ventricular ejection fraction was 35% or less in 36% of patients. An interdisciplinary heart team of cardiologists and cardiac surgeons discussed all patients.ResultsPercutaneous clip implantation was successful in 186 patients (92%). Patients were treated with 1 clip (n = 125; 62%), 2 clips (n = 64; 32%), or 3 or more clips (n = 7; 3%). Reduction in mitral regurgitation from pre- to postprocedure was significant (P < .0001) and remained stable within the first 12 months in the majority of patients. Thirty-day mortality was 3.5% (7/202 patients). Hospital stay was 12 ± 10 days, and median intensive care unit stay was 1 day (range, 0–45 days). Eleven patients required surgical valve repair/replacement at a median of 38 days (0–468 days) after percutaneous clip implantation.ConclusionsClip-based percutaneous mitral valve repair is a safe, low-risk, and effective therapeutic option in symptomatic patients with a high risk for surgery and does not exclude later surgical repair

Bergbaumonitoring im südlichen Ruhrgebiet

Der verantwortungsbewusste Umgang mit alt- und nachbergbaulichen Strukturen umfasst den Aufbau und die Entwicklung eines integrierten Risikomanagementsystems. Daher ist es wichtig, aktuelle Informationen über die bergbaulichen Elemente, ihren Zustand und mögliche Auswirkungen auf die Tagesoberfläche mittels verschiedener Monitoringmethoden zu ermitteln. Die Überwachung mittels Methoden der satellitengestützten Erdbeobachtung generiert Sensordaten, die mit in-situ Datensätzen zu validieren sind. Im Projekt "Gemeinsames Monitoring im Altbergbau" wurden für die Altgesellschaften des Steinkohlenbergbaus im südlichen Ruhrgebiet in einer ersten Projektphase die Elemente des Alt- und Nachbergbaus, die möglichen Ereignisse und die Parameter zur Detektion und die Möglichkeit der Messung der Ereignisse integriert betrachtet. In der aktuell laufenden zweiten Projektphase werden Radardaten des EU-Copernicus Programmes genutzt, um Bodenbewegungen mittels radarinterferometrischer PSI- und DSI-Methoden zu detektieren. Hierbei kommen innovative Methoden zur frühzeitigen Integration der Oberflächennutzung zur Anwendung, um so eine bessere Klassifizierung und Signifikanzanalyse der Bodenbewegung zu erreichen. Der Auswerteprozess wird zusätzlich mit alt- und nachbergbaulichen in-situ Daten angereichert. Das Projekt "Gemeinsames Monitoring im Altbergbau" bietet somit zukünftig die Möglichkeit alt- und nachbergbauliche Fragestellungen im Rahmen eines integrierten Risikomanagementsystems zu beantworten