Design and Development in the Field of Alkaline Fuel Cell Technology

This thesis is about the research on alkaline fuel cell (AFC) technology to investigate the long term operation with air. The aim was to solve the two main problems arising from long term operation and especially from operation with air: • Dilution of the liquid electrolyte by the water from the reaction • Cell damage due to the formation of carbonate In recent years the development of fuel cells has gained a growing interest again. However the interest in alkaline fuel cells was low as the polymer electrolyte membrane fuel cell (PEMFC) seemed to be the superior system. One reason for this is this is the estimation that the AFC cannot be operated with air because of the reaction of CO2 and the electrolyte potassium hydroxide solution (KOH). This research project shows that it is possible to operate the AFC with air and hydrogen in place of pure oxygen and hydrogen. First of all tests were made with gas diffusion electrodes (GDEs) that are used to build the fuel cell. The electrodes were operated with air in a half cell. Even after thousand of hours in operation with unfiltered air no significant decrease of power was detectable. But testing electrodes in a half cell in only one part. The only way to get reliable results is to test the electrodes under real conditions; Long term operation in the alkaline fuel cell. For this purpose fuel cells were built with O2-electrodes that were manufactured according to the results of the half cell tests. In addition, many changes had to be done to develop the fuel cell and adopt it to the demands of the operation with air. The results are presented and discussed in this thesis. In the end it was possible to operate the AFC for several hundred hours with unfiltered air without damaging the cell. Proposals for future work are also given

Fusion of isolated myoblast plasma membranes

Fusion of plasma membranes isolated from myoblasts grown in culture has been investigated. 1. 1. Membrane fusion was specifically dependent on Ca2+ at physiological concentrations. However, at higher concentrations of cations, fusion could be triggered not only by Ca2+, but by Mg2+ and Sr2+ as well. 2. 2. The amount of fusion was directly proportional to temperature. 3. 3. Fusion was found to depend on the state of maturation of the myoblast membranes. 4. 4. Experiments with chemically and enzymatically modified membranes and with membranes derived from myoblasts grown in the presence of inhibitors of protein biosynthesis suggest the participation of proteinaceous membrane components in the fusion mechanism

Gamma Group-The Pale Horse: A proposal in response to a commercial air transportation study ort study

A conventional remotely piloted vehicle (RPV) was designed to operate in a fictional 'Aeroworld' as a 30 passenger aircraft. The topics addressed include: economic/cost analysis, aerodynamics, weight and structures, propulsion, stability and control, and performance

Ca2+-induced fusion of Golgi-derived secretory vesicles isolated from rat liver

During the transport of plasma proteins from the cytoplasma of hepatocytes to the extracellular fluid srnall vesicles may act as shuttles between the Golgi complex and the plasma membrane. This type of intracellular transfer is weil established for various secretory cells and may be adopted also for the hepatocyte. Recent investigations have shown that secretory vesicles fuse with each other during secretion in mast cells [4] exocrine [5,6] and endocrine pancreatic tissue [7]. The intervesicular fusion provides a tool for studies on membrane fusion, since Golgi-derived vesicles can be isolated from the hepatocyte and their interaction with various agents, suggested to trigger membrane fusion, can be monitored by freeze-cleaving

Kiri J. B. Rentzile, Frankfurt

http://tartu.ester.ee/record=b1880793~S1*es

Chemical informatics uncovers a new role for moexipril as a novel inhibitor of cAMP phosphodiesterase-4 (PDE4)

PDE4 is one of eleven known cyclic nucleotide phosphodiesterase families and plays a pivotal role in mediating hydrolytic degradation of the important cyclic nucleotide second messenger, cyclic 3′5′ adenosine monophosphate (cAMP). PDE4 inhibitors are known to have anti-inflammatory properties, but their use in the clinic has been hampered by mechanism-associated side effects that limit maximally tolerated doses. In an attempt to initiate the development of better-tolerated PDE4 inhibitors we have surveyed existing approved drugs for PDE4-inhibitory activity. With this objective, we utilised a high-throughput computational approach that identified moexipril, a well tolerated and safe angiotensin-converting enzyme (ACE) inhibitor, as a PDE4 inhibitor. Experimentally we showed that moexipril and two structurally related analogues acted in the micro molar range to inhibit PDE4 activity. Employing a FRET-based biosensor constructed from the nucleotide binding domain of the type 1 exchange protein activated by cAMP, EPAC1, we demonstrated that moexipril markedly potentiated the ability of forskolin to increase intracellular cAMP levels. Finally, we demonstrated that the PDE4 inhibitory effect of moexipril is functionally able to induce phosphorylation of the Hsp20 by cAMP dependent protein kinase A. Our data suggest that moexipril is a bona fide PDE4 inhibitor that may provide the starting point for development of novel PDE4 inhibitors with an improved therapeutic window

Fusion of secretory vesicles isolated from rat liver

Secretory vesicles isolated from rat liver were found to fuse after exposure to Ca2+. Vescle fusion is characterized by the occurrence of twinned vesicles with a continuous cleavage plane between two vesicles in freeze-fracture electron microscopy. The number of fused vesicles increases with increasing Ca2+-concentrations and is half maximal around 10–6 m. Other divalent cations (Ba2+, Sr2+, and Mg2+) were ineffective. Mg2+ inhibits Ca2+-induced fusion. Therefore, the fusion of secretory vesiclesin vitro is Ca2+ specific and exhibits properties similar to the exocytotic process of various secretory cells. Various substances affecting secretionin vivo (microtubular inhibitors, local anethetics, ionophores) were tested for their effect on membrane fusion in our system. The fusion of isolated secretory vesicles from liver was found to differ from that of pure phospholipid membranes in its temperature dependence, in its much lower requirement for Ca2+, and in its Ca2+-specificity. Chemical and enzymatic modifications of the vesicle membrane indicate that glycoproteins may account for these differences