Coupled 3D master equation and 1D drift‐diffusion approach for advanced OLED modeling

A novel simulation approach for excitonic organic light‐emitting diodes (OLEDs) is established by combining a continuous one‐dimensional (1D) drift‐diffusion (DD) model for the charge carrier dynamics with a three‐dimensional (3D) master equation (ME) model describing the exciton dynamics in a multilayer OLED stack with an additional coupling to a thin‐film optics solver. This approach effectively combines the computational efficiency of the 1D DD solver with the physical accuracy of a discrete 3D ME model, where excitonic long‐range interactions for energy transfer can be taken into account. The coupling is established through different possible charge recombination types as well as the carrier densities themselves. We show that such a hybrid approach can efficiently and accurately describe steady‐state and transient behavior of optoelectronic devices reported in literature. Such a tool will facilitate the optimization and characterization of multilayer OLEDs and other organic semiconductor devices.     

Regelung und Steuerung von thermoaktiven Bauteilsystemen (TABS)

Thermoaktive Bauteilsysteme (TABS) haben eine zunehmende Bedeutung bei der energieeffizienten Kühlung und Heizung von Gebäuden, doch ihre Regelung/Steuerung führt in der Praxis oft zu Problemen. Mit dem Ziel, diese Probleme in den Griff zu bekommen, wurde vor fünf Jahren das Forschungsprojekt TABS‐Control gestartet, das zu Beginnd des Jahres 2009 abgeschlossen wurde. Es wurden folgende wesentliche Resultate erarbeitet: Modelle und Simulationsprogramme für TABS; Performance‐Bound‐Berechnungen für die Zonenregelung; eine Auswahl von Regel‐/ Steuer‐Strategien für die Zonenregelung, u. a. mit Lösungen für das automatische Umschalten zwischen Heizen und Kühlen, für den Taktbetrieb der Zonenpumpe und für eine Raumtemperaturregelung; Implementierung von Standardlösungen in einem Gebäudeautomationssystem; Labortests; das neue UBB‐Planungsverfahren (Unknown‐But‐Bounded) zur integrierten Planung von TABS und ihrer Regelung/Steuerung; ein Excel‐Planungstool; Richtlinien zur Wahl der Topologie der hydraulischen Schaltung; eine Methode zur Betriebsoptimierung; eine theoretische Grundlage (UBB‐Ansatz) für das neue integrierte Planungsverfahren und die neuen Regel‐/Steuer‐Strategien; eine Patentanmeldung. Regulation and control of thermally activated building systems (TABS). Thermally activated building systems (TABS) are becoming increasingly important in terms of energy efficient cooling and heating of buildings. In practice, however, regulation and control of such systems often causes problems. Started five years ago with the aim of getting to grips with these problems, the TABS Control research project was completed in early 2009. The project yielded the following results: various models and simulation programs for TABS; performance‐bound calculations for regulating zones; a range of zone regulation/control strategies for planners to choose from, including good solutions for automatic switching between heating and cooling, for pulsed operation of the zone pump and for room temperature control; the implementation of a subset of these strategies as standard solutions in a Siemens building automation system; laboratory tests on these strategies; a new procedure for the integrated planning of TABS and their regulation/control (referred to as UBB planning procedure – Unknown But Bounded); an Excel planning tool; guidelines on selecting the hydraulic switching topology; a method for operation optimization; the theoretical basis for the new integrated planning procedure and the new regulation/ control strategies; a patent application.     

Clinical use of high-efficiency hemodialysis treatments: long-term assessment

Significant technological changes in blood flow rate, dialyzer membrane permeability, bicarbonate dialysate, and ultrafiltration-controlled delivery systems permitted the implementation of 3 modifications to conventional hemodialysis as follows: high-efficiency hemodialysis (HEHD), high-flux hemodialysis (HFHD), and double-high-flux hemodiafiltration (HDF). The impact of these techniques on the quantity of the treatment administered and treatment time were assessed. One hundred and eighty-three patients were enrolled over 6 years. Monthly Kt/Vurea and dialysis treatment time were compared among the treatment techniques. In vivo extracorporeal clearances were measured for the dialyzers used. In vivo kinetically derived effective dialyzer clearances were calculated from Kt/V. Patient survival and standardized mortality ratio (SMR) were determined for each treatment modality. Treatment time averaged 192+/-28, 176+/-29, and 159+/-32 min, Kt/Vurea averaged 1.33+/-.34, 1.29+/-.30, 1.41+/-.32, and in vivo delivered urea clearance averaged 222+/-51, 272+/-34, and 333+/-43 mL/min for HEHD, HFHD, and HDF, respectively. These results were achieved even in patients with body weights in excess of 80 kgs. Net ultrafiltration rate during the treatment reached 20-30 mL/min, without clinical untoward effects. Blood flow rate ranged between 450-650 mL/min in all patients. Kaplan-Meier Survival analysis yielded a significant difference when high-efficiency treatments were compared with USRDS outcomes. Standardized mortality ratio analysis showed significance for only HDF vs. USRDS. High-efficiency treatments can provide the same quantity of treatment in a shorter period of time without affecting mortality. The increased spectrum of solutes removal provided by HFHD and HDF may be a further advantage of these treatments.     

Würde der Kreatur versus Menschenwürde?

Das Konzept der Würde der Kreatur fand bekanntlich (Vgl. z. B. Baranzke (2002, Seiten 11 und 15 sowie 2007, Seite 25) und Sitter-Liver (2008, Seiten 161 u.a.) und Odparlik (2007, Seite 73 f.)) am 17. Mai 1992 Eingang in die Bundesverfassung der Schweizerischen Eidgenossenschaft (Der entsprechende Passus aus Art. 24^novies aBV wurde ohne ?nderung in die Totalrevision von 1999 übernommen und figuriert dort neu als Art. 120 Abs. 2 BV: "Der Bund erl?sst Vorschriften über den Umgang mit Keim- und Erbgut von Tieren, Pflanzen und anderen Organismen. Er tr?gt dabei der Würde der Kreatur sowie der Sicherheit von Mensch, Tier und Umwelt Rechnung und schützt die genetische Vielfalt der Tier- und Pflanzenarten"). Es l?ste zun?chst bei Juristen, Theologen und Philosophen eine rege Diskussion aus. Mittlerweile ist es wegen seiner wirtschaftlichen und wissenschaftspolitischen Brisanz auch auf politischer Ebene ein hei?es Thema. Würde der Kreatur wird für die einen zur Gef?hrdung der Menschenwürde, w?hrend die anderen eintreten für die Anerkennung und Wahrung der Würde sowohl der Menschen als auch der nicht-menschlichen Lebewesen, letztlich der natürlichen Entit?ten insgesamt.     

Tuning of electrical and optical properties of organic LEDs using combinatorial device fabrication

The capabilities of combinatorial methods are presented in order to get a detailed understanding of the electrical and optical properties of organic light‐emitting devices (OLEDs), to optimize their performance, and to provide reliable data for device modeling. We show results on multilayer OLEDs ranging from the conventional copper‐phthalocyanine (CuPc)/N,N′di‐(naphtalene‐1‐yl)‐N,N′‐diphenyl‐benzidine (NPB) and tris‐(8‐hydroxy‐quinolinato)aluminum (Alq) tri‐layer device to double‐doped deep‐red‐emitting OLEDs.     

Large fluctuations in the disassembly rate of microtubules revealed by atomic force microscopy

Atomic force microscopy (AFM) in situ has been used to observe the cold disassembly dynamics of microtubules at a previously unrealised spatial resolution. Microtubules either electrostatically or covalently bound to aminosilane surfaces disassembled at room temperature under buffer solutions with no free tubulin present. This process was followed by taking sequential tapping-mode AFM images and measuring the change in the microtubule end position as a function of time, with an spatial accuracy down to +/-20nm and a temporal accuracy of +/-1s. As well as giving average disassembly rates on the order of 1-10 tubulin monomers per second, large fluctuations in the disassembly rate were revealed, indicating that the process is far from smooth and linear under these experimental conditions. The surface bound rates measured here are comparable to the rates for GMPCPP-tubulin microtubules free in solution, suggesting that inhibition of tubulin curvature through steric hindrance controls the average, relatively low disassembly rate. The large fluctuations in this rate are thought to be due to multiple pathways in the kinetics of disassembly with differing rate constants and/or stalling due to defects in the microtubule lattice. Microtubules that were covalently bound to the surface left behind the protofilaments covalently cross-linked to the aminosilane via glutaraldehyde during the disassembly process. Further work is needed to quantitatively assess the effects of surface binding on protofibril disassembly rates, reveal any differences in disassembly rates between the plus and minus ends and to enable assembly as well as disassembly to be imaged in the microscope fluid cell in real-time.     

Assessment of prosthetic aortic valve performance by magnetic resonance velocity imaging

Objectives Magnetic resonance (MRI) velocity mapping was used to evaluate non-invasively the flow profiles of the ascending aorta in normal volunteers and in patients with an aortic (mechanical) valve prosthesis. Background In patients with artificial aortic valves the flow profile in the ascending aorta is severely altered. These changes have been associated with an increased risk of thrombus formation and mechanical hemolysis. Methods Velocity profiles were determined 30 mm distal to the aortic valve in six healthy volunteers and seven patients with aortic valve replacement (replacement within the last 2 years) using ECG triggered phase contrast MRI. Peak flow, mean flow and mean reverse flow were measured in intervals of 25 ms during the entire heart cycle. Systolic reverse flow, end-systolic closing and diastolic leakage volume were calculated for all subjects. Results Peak flow velocity during mid-systole was significantly higher in patients with valvular prosthesis than in normals (mean±SD, 1.9±0.4 m/s vs. 1.2±0.03 m/s,P<0.001) with a double peak and a zone of reversed flow close to the inner (left lateral) wall of the ascending aorta of the patients. Closing volume was significantly larger in patients than in controls (−3.3±1.2 ml/beat vs. −0.9±0.5 ml/beat;P<0.001). There was reverse flow during systole in valvular patients amounting to 15.7±6.7% of total cardiac output compared to 2.3±1.2% in controls (P<0.001). Diastolic mean flow was negative in patients after valve replacement but not in controls (−11.0±15.2 ml/beat vs. 6.8±3.2 ml/beat;P<0.01). Conclusions The following three major quantitative observations have been made in the present study: (1) Mechanical valve prostheses have an increased peak flow velocity with a systolic reverse flow at the inner (left lateral) wall of the ascending aorta. (2) A double peak flow velocity pattern can be observed in patients with bileaflet (mechanical) prosthesis. (3) The blood volume required for leaflet closure and the diastolic leakage blood volume are significantly higher for the examined bileaflet valve than for native heart valves.