Chromophors for two-photon absorption

Ziel der Arbeit war die Entwicklung und Synthese von Farbstoffen mit der Befähigung zur Zweiphotonenabsorption. Die maßgeschneiderten Chromophore sollten in der Zweiphotonenlaserrastermikroskopie (TPLSM) einsetzbar sein. Dazu wurden Design-Kriterien aufgestellt und ausgewählte Vetreter von vier Substanzklassen (Pyrazolo[1,2-a]pyrazol-1,7-dione, Benzo[2,1-b:3,4-b´]dithiophene, Dibenzothiophene und Dibenzothiophen-S,S-dioxide) synthetisiert. Ihre linear und nichtlinear optischen Eigenschaften wurden anhand von Absorptions-, Fluoreszenz- und Zweiphotonenanregungsspektren umfassend untersucht. N,N,N´N´-Tetraaryldibenzothiophen-S,S-dioxid-3,7-diamine erwiesen sich für die TPLSM als besonders geeignet. Sie wurden vom Kooperationspartner in TPLSM- und Fluoreszenzlebensdauer (FLIM)-Aufnahmen von Pflanzenzellen und Humanhaut eingesetzt.Target of this work was the developement and synthesis of dyes with the ability to undergo two-photon absorption. The taylor-made chromophores should be used for Two-photon Laser scanning microscopy (TPLSM). Therefore, design criteria were determined and chosen molecules from four different classes (Pyrazolo[1,2-a]pyrazol-1,7-diones, Benzo[2,1-b:3,4-b´]dithiophenes, Dibenzothiophenes and Dibenzothiophen-S,S-dioxides) have been synthesized. Their linear and nonlinear optical properties were investigated intensively by using UV/Vis, fluorescence and two-photon excitation spectroscopy. Especially N,N,N´N´-Tetraaryldibenzothiophene-S,S-dioxide-3,7-diamines have been proved to be suitable for TPLSM. They were used by co-operators for TPLSM- and fluorescence lifetime imaging (FLIM) of plant cells and human skin

On discontinuous Galerkin approach for atmospheric flow in the mesoscale with and without moisture

We present and discuss discontinuous Galerkin (DG) schemes for dry and moist atmospheric flows in the mesoscale. We derive terrain-following coordinates on the sphere in strong-conservation form, which makes it possible to perform the computation on a Cartesian grid and yet conserves the momentum density on an f -plane. A new DG model, i.e. DG-COSMO, is compared to the operational model COSMO of the Deutscher Wetterdienst (DWD). A simplified version of the suggested terrain-following coordinates is implemented in DG-COSMO and is compared against the DG dynamical core implemented within the DUNE framework, which uses unstructured grids to capture orography. Finally, a few idealised test cases, including 3d and moisture, are used for validation. In addition an estimate of efficiency for locally adaptive grids is derived for locally and non-locally occurring phenomena.publishedVersio

LIHYP - Linking Hydrogen Power Potentials in the North Sea Region

Vorstellung des LIHYP-Projektpiloten aus Oldenburg. Es ist geplant zwei E-Lastenräder mit integrierter Brennstoffzelle zu testen (in der Anwendung bei einem Logistikdienstleister aus Oldenburg und im Labor)

Fuel Cell Electrical Vehicles as Mobile Coupled Heat and Power Backup-Plant in Neighbourhoods

Fuel cell electric vehicles (FCEVs) can be used during idle times to convert hydrogen into electricity in a decentralised manner, thus ensuring a completely renewable energy supply. In addition to the electric power, waste heat is generated in the fuel cell stack that can also be used. This paper investigates how the energy demand of a compiled German neighbourhood can be met by FCEVs and identifies potential technical problems. For this purpose, energy scenarios are modelled in the Open Energy System Modelling Framework (oemof). An optimisation simulation finds the most energetically favourable solution for the 10-day period under consideration. Up to 49% of the heat demand for heating and hot water can be covered directly by the waste heat of the FCEVs. As the number of battery electric vehicles (BEVs) to be charged increases, so does this share. 5 of the 252 residents must permanently provide an FCEV to supply the neighbourhood. The amount of hydrogen required was identified as a problem. If the vehicles cannot be supplied with hydrogen in a stationary way, 15 times more vehicles are needed than required in terms of performance due to the energy demand

Exploring the Feasibility of Battery Electric and Fuel Cell Electric Vehicles as Peaker Plant Substitutes at Low Wind and Irradiation Conditions

In this paper a comparison between the use of Battery Electric Vehicles (BEVs) and Fuel Cell Electric Vehicles (FCEVs) to span cold dark doldrums (“Dunkelflaute”) in a future energy system with a high penetration of renewable energy supply is presented. A big problem with the cold dark doldrums is the rareness of the situation. Any power plant built to specifically be used during those special weather conditions will be operated only 0.1 % of the time according to a study on the energy demand in Germany in 2050 Aurora (2021) even though 10 GW are required to meet the demand. A prototype FCEV docking station to measure power transfer efficiencies was built. By this, we investigated supplying a district with energy via FCEVs by simulating a district with varying amounts of BEVs present. It is possible to supply a district with a low number of FCEVs although a stationary hydrogen connection would be beneficial. The efficient transfer of energy from a FCEV to a building requires a careful design of the plate heat exchangers and depends on the temperature level of the supplied building

Review of Hydrogen Production Techniques from Water Using Renewable Energy Sources and Its Storage in Salt Caverns

Hydrogen is becoming an increasingly important energy carrier in sector integration for fuel cell transportation, heat and electricity. Underground salt caverns are one of the most promising ways to store the hydrogen obtained from water electrolysis using power generation from renewable energy sources (RES). At the same time, the production of hydrogen can be used to avoid energy curtailments during times of low electricity demand or low prices. The stored hydrogen can also be used during times of high energy demand for power generation, e.g., with fuel cells, to cover the fluctuations and shortages caused by low RES generation. This article presents an overview of the techniques that were used and proposed for using excess energy from RES for hydrogen production from water and its storage techniques, especially in underground salt caverns, for the aforementioned purpose, and its feasibility. This paper compares and summarizes the competing technologies based on the current state-of-the-art, identifies some of the difficulties in hydrogen production and storage, and discusses which technology is the most promising. The related analysis compares cost and techno-economic feasibility with regard to hydrogen production and storage systems. The paper also identifies the potential, technical challenges and the limitations associated with hydrogen integration into the power grid