Average transmission probability of a random stack

The transmission through a stack of identical slabs that are separated by gaps with random widths is usually treated by calculating the average of the logarithm of the transmission probability. We show how to calculate the average of the transmission probability itself with the aid of a recurrence relation and derive analytical upper and lower bounds. The upper bound, when used as an approximation for the transmission probability, is unreasonably good and we conjecture that it is asymptotically exact.Comment: 10 pages, 6 figure

Für mehr Zirkularität - Flächenbedarfe der Bauschuttaufbereitung als Grundlage zur Kreislaufführung mineralischer Bau- und Abbruchmaterialien

Der Einsatz hochqualitativer, mineralischer Sekundärrohstoffe spielt im sächsischen Bausektor eine untergeordnete Rolle. Fehlende Informationen und Planungen über geeignete Flächen zur Errichtung von Bauschuttaufbereitungsanlagen zur Herstellung von Sekundärmaterialien hemmen den Ausbau der Aufbereitungskapazitäten. Das vorgestellte Flächenbedarfsabschätzungs-Tool soll dem entgegenwirken. Es ermöglicht anhand identifizierter Kriterien die Suche nach geeigneten Flächen sowie das Ranking potenzieller Standorte und damit den Abgleich von Flächenbedarf und -angebot auf Basis frei verfügbarer Geodaten. Erste Ergebnisse der Analysen zeigen, dass die Flächennachfrage größer ist als das Flächenangebot. Perspektivisch muss diese Flächennachfrage im Zuge der strategischen Flächennutzungs- und Regionalplanung berücksichtigt werden, wenn die Kapazitäten der Bauschuttaufbereitung erhöht werden sollen. Das Flächenbedarfsabschätzungs-Tool soll den Planungsträgern zur eigenständigen Nutzung übergeben werden und so Planungsprozesse unterstützen

Cycloaddition Reactions of the Diphosphenyl Complex (η5-C5Me5)(CO)2Fe-P=P-Mes* (Mes* = 2,4,6-tBu3C6H2) with Hexafluoroacetone. X-Ray Structure Analyses of (η5-C5Me5)(CO) Fe P(=PMes*)OC(CF3)2CO and (η5-C5Me5)(CO)2FePP(Mes*)OC(CF3)2

Weber L, Buchwald S, Lentz D, Preugschat D, Stammler H-G, Neumann B. Cycloaddition Reactions of the Diphosphenyl Complex (η5-C5Me5)(CO)2Fe-P=P-Mes* (Mes* = 2,4,6-tBu3C6H2) with Hexafluoroacetone. X-Ray Structure Analyses of (η5-C5Me5)(CO) Fe P(=PMes*)OC(CF3)2CO and (η5-C5Me5)(CO)2FePP(Mes*)OC(CF3)2. Organometallics. 1992;11(7):2351-2353.The diphosphenyl complex (eta-5-C5Me5)-(CO)2Fe-P=P-Mes* (Mes* = 2,4,6-tBu3C6H2) undergoes a [3 + 2] dipolar cycloaddition with hexafluoroacetone to give the metalla heterocycle (eta-5-C5Me5)(CO)-Fe-P(=PMes*)OC(CF3)2C(O) with a remarkably short Fe-P bond (2.084 (4) angstrom) and an exocyclic P=P bond. When stored in solution at -40-degrees-C, this complex partly rearranges to the metalated 1-oxa-2,3-diphosphetane (eta-5-C5Me5)(CO)2Fe-P-P(Mes*)OC(CF3)2. The molecular structures of both isomers were elucidated by single-crystal X-ray analyses

Development of an in-vitro model for extracorporeal blood pumps to study the effects of artificial pulsatility on human blood

IntroductionThe application of extracorporeal circulation (ECC) systems is known to be associated with several implications regarding hemolysis, inflammation, and coagulation. In the last years, systems with pulsatile blood flow are increasingly used with the intention to improve hemodynamics in reperfusion. However, their implications on the aforementioned aspects remain largely unknown. To investigate the effects of pulsatility, this ex-vivo study was initiated.MethodsTest circuits (primed with human whole blood) were set up in accordance with the recommendations of international standards for in-vitro evaluation of new components and systems of ECC. Diagonal pumps were either set up with non-pulsatile (n = 5, NPG) or pulsatile (n = 5, PG) pump settings and evaluated for 6 h. All analyses were conducted with human whole blood. Blood samples were repeatedly drawn from the test circuits and analyzed regarding free hemoglobin, interleukin 8 (IL-8), platelet aggregation and acquired von Willebrand syndrome (AVWS).ResultsAfter 1 h of circulation, a significant coagulation impairment (impaired platelet function and AVWS) was observed in both groups. After 6 h of circulation, increased IL-8 concentrations were measured in both groups (NPG: 0.05 ± 0.03 pg./mL, PG: 0.03 ± 0.01 pg./mL, p = 0.48). Pulsatile pump flow resulted in significantly increased hemolysis after 6 h of circulation (NPG: 37.3 ± 12.4 mg/100 L; PG: 59.6 ± 14.5 mg/100 L; p < 0.05).ConclusionOur results indicate that the coagulative impairment takes place in the early phase of ECC. Pulsatility did not affect the occurrence of AVWS ex-vivo. Prolonged durations of pulsatile pump flow led to increased hemolysis and therefore, its prolonged use should be employed cautiously in clinical practice with appropriate monitoring