Accurate optical simulation of disordered scattering layers for light extraction from organic light emitting diodes

Diese Arbeit handelt von einer Methode zur umfassenden optischen Simulation von organischen Leuchtdioden (OLEDs) mit internen ungeordneten Streuschichten zur Lichtauskopplung. Die Methode ist exakt in dem Sinne, dass sie die L\"osung der Maxwellgleichungen f\"ur Dipolstrahlung in einem planparallelen Schichtsystem mit mehreren Streupartikeln erm\"oglicht. Dies wird durch die Entwicklung des gestreuten elektromagnetischen Feldes in Kugelvektorwellenfunktionen (zur effizienten Handhabung der Streuung an den einzelnen Partikeln) sowie in ebenen Wellen (zur Handhabung der Propagation des Lichtes durchs D\"unnschichtsystem) erreicht. Nach einer Einf\"uhrung zum Thema OLEDs mit einem besonderen Augenmerk auf Lichtauskopplung werden die relevanten Formeln f\"ur die Mehrfachstreuung in einem Formalismus von Anregung und Systemantwort hergeleitet. Auf diese Weise kann das Streuproblem in ein System von linearen Gleichungen \"uberf\"uhrt werden, das auf der Grundlage des T-Matrix Formalismus\u27 die Berechnung der Streukoeffizienten erlaubt. Es werden auch numerische Aspekte einer effizienten Aufstellung und L\"osung dieses Gleichungssystemes er\"ortert und Gleichungen, welche die Berechnung der interessanten Kenngr\"o\ss{}en erm\"oglichen, werden hergeleitet (elektrische Feldverteilung, dissipierte Leistung, Leistungsfluss durch Grenzfl\"achen, Fernfeld-Intensit\"atsverteilungen). Die hier vorgestellte Simulationsmethode wurde auch in einer frei verf\"ugbaren Software (\emph{Smuthi}) implementiert. Die Programmstruktur von Smuthi wird skizziert, und die Korrektheit der Simulationsergebnisse wird durch einen Vergleich mit Finite-Elemente Rechnungen belegt. Abschlie\ss{}end wird die Simulationsmethode an Hand einer praxisrelevanten Fallstudie illustriert. Hierzu wird eine wei\ss{}e OLED, deren Auskoppeleffizienz bereits durch Anpassen der Schichtdicken und der Lage der Emissionszonen optimiert worden ist, mit einer internen Streuschicht versehen und der erwartbare Zugewinn in der Lichtausbeute durch Simulationen berechnet. Au\ss{}er der Lichtauskopplung aus OLEDs kann der hier pr\"asentierte theoretische Formalismus und die Software f\"ur zahlreiche andere Anwendungen genutzt werden, welche die Streuung von Licht an Partikeln in der N\"ahe von ebenen Grenzfl\"achen beinhalten

Presence and Function of Intermediate Filament Protein Synemin in Proliferative Tissues

Synemin intermediate filament (IF) protein is unlike other members of the IF protein family due to its size, structure, and pattern of expression. Synemin polymerizes with Type III IF proteins and is found in a wide variety of tissues, most of which are mesenchymal in origin. However, the presence of synemin in tumors of mesenchymal origin is unknown. Because IF proteins are widely used to identify tumor types as well as to predict the clinical outcomes of tumors, we have evaluated by immunoperoxidase the presence of synemin in fifty-three tumors of mesenchymal origin (sarcomas). The majority (62%) of the sarcomas examined exhibited 1.0% to 10.0% cytoplasmic positivity for synemin. There was also a significant number of cases (21%) with particularly intense (\u3e30.0%) synemin staining, including all five gastrointestinal stromal cell tumors (GIST). The presence of synemin in GIST was further evaluated by immunoperoxidase in fifty-four cases of GIST and was compared to that of CD34, one of the markers currently used to identify GIST tumors. The results show that synemin is a more sensitive marker than CD34 in identifying GIST. Additionally, synemin was found in interstitial cells of Cajal (ICC), the pacemaker cells which regulate peristalsis in the gastrointestinal tract and which give rise to GIST. Early studies have shown that synemin is present in amphibian and avian nucleated red blood cells. This prompted us to examine by immunofluorescence the expression of synemin in erythroblasts, which are the nucleated precursors of red blood cells and are located in the bone marrow. Our results suggest that synemin may be present in a subpopulation of erythroblasts. They also demonstrate that, unexpectedly, synemin is consistently present in platelets and in their precursors, the megakaryocytes, suggesting that synemin may play a role in platelet shedding by megakaryocytes. Finally, synemin is present in neurons of the peripheral nervous system (PNS). Since IF proteins other than synemin have been shown to be key regulators of axonal caliber, we examined the role of synemin in N2a neuroblastoma cells, which are derived from PNS neurons. We used CRISPr/Cas9 to knock down synemin in N2a neuroblastoma cells. Our results demonstrate that synemin is a positive regulator of N2a cell proliferation, but that it does not play a role in the extension of neurites by these cells. However, synemin was involved in determining the size of the cell body of N2a cells.Altogether, our results suggest that synemin is more widely expressed than previously thought, which raises questions as to its role(s) in the different cell types in which it is expressed. Our results with N2a cells also suggest that in tumor cells, the primary role of synemin is that of a positive regulator of cell proliferation

Effect of biochar on microbial biomass and biological nitrogen fixation

Biochar is a product from the pyrolysis of plant derived-biomass and it is intended to be applied to soil given its potential of carbon sequestration and soil fertility improvement. Some studies also suggest that increasing application rate of biochar has a positive feedback on biological nitrogen fixation (BNF) and on soil microbial biomass. However, these effects are not well known for boreal forests. The purpose of this study was to evaluate the effects of different biochar application rates: 0 t ha-1, 5 t ha-1 and 10 t ha-1 on BNF, on microbial biomass carbon and nitrogen (MBC and MBN), and on moss biomass. The field experiment was established in Juupajoki, Southern Finland in young Scots pine stands. The stands were amended with biochar one year before the measurements took place. BNF was determined using acetylene reduction assay (ARA), and microbial biomass was estimated using chloroform fumigation-direct extraction (CFDE). The microbial biomass samples were incubated at the temperatures: 10 °C, 15 °C and 20 °C. Biochar amendment raised soil pH, whereas no differences were verified for BNF, MBC, MBN, nor for moss biomass. There was, however, variation in the response of N fixation to incubation temperature, and variation in the response of MBC and MBN to the time of measurement. Observed changes in pH are often likely to justify variations in the rates of BNF and MB, however in this study they were not shown to be of significance. It is possible, however that biochar will have a positive effect on soil vegetation as it is incorporated into the soil in the long-term. Although this study focuses on BNF and MB, the findings may well have a bearing on the use of biochar as a tool for C sequestration, since amendment with biochar was demonstrated as neither beneficial nor harmful to the soil biota

Reduction of rainfall reaching the ground by deciduous trees on the edge of stands - a study into incremental wet canopy evaporation through storm events

Can deciduous trees be used to reduce hydrograph peaks? This is an intriguing question to scientists, charities, and the public alike and the answer is yes. It is beneficial to understand how hydrological processes are influenced by edge effects and differs from other studies that are 100+m into woodlands, due to the planting of narrow belts for natural flood management. This research quantifies the WCE (Wet Canopy Evaporation) of a mature Chestnut tree through storms between May 2018 and April 2019, combined with manual weekly volumetric data from three Beech and two Oak trees in a narrow woodland on the Lancaster University campus. From the six trees studied, the WCE% during the measurement period was 41.97% of gross-rainfall, while the remainder of the gross-rainfall was partitioned into throughfall (54.39%) and stemflow (3.65%). The WCE% of the tree species (excluding the chestnut tree) are significantly higher than that found in other studies where measurements are taken 100s of metres into woodlands away from edge effects; but this data agrees with Herbst et al.’s (2006) findings relating to WCE of hedges. In part this is due to the greater ventilation of the canopy and stems. Although lower than during the leafed periods, WCE remained high from leafless branches and stems. It was also found that the WCE% decreases as storm size increases. The Frumau horizontal and vertical rain gauges (Frumau et al., 2011. Hydrological Processes 25: 499-509) found that horizontal rainfall caused under-estimation of gross rainfall collected by the tree, which was influenced by wind speed and direction. Negative WCE (i.e. larger throughfall than rainfall) was seen as the tree collected rainfall from a larger area. If corrected rainfall was known the WCE would be larger. The Penman equation showed a poor fit, overestimating evaporation as it shows potential WCE. With little improvement in the utilisation of stores, the Rutter original underestimates evaporation that occurs. The Rutter Sparse model provided the best fit, but was still poor, underestimating evaporation. The Rutter Sparse parameters were altered showing the best fit altering the aerodynamic resistance to 5s/m rather than converting Hazelrigg weather stations wind speed. Alternatively, the canopy capacity was increased and throughfall coefficient decreased to produce a good fit, however these were calculated using the data collected suggesting the best alterations to the model account for the edge effect better by altering the aerodynamic resistance. The research highlights how model parameters representative of conditions at the centre of large woodland blocks should not be used to estimate WCE for narrow belts of trees. Indeed, narrow tree belts could be considered as potential ‘hot spots’ of evaporation requiring more direct measurements to understand their significance as a tool for removing net-rainfall from catchment systems during flood peaks

Electrospun Composite Nanofibers for Functional Applications

This reprint includes research articles on various applications of electrospun nanofibers. Nanofibers have potential to be used in tissue engineering, energy harvesting, sensors, separators, water filtration, air filtration, and other applications as well. This Special Issue has received 11 interesting research articles, which covers such application areas