Votum der Ethikkommission der Medizinischen Universität zu Lübeck zur Präimplantationsdiagnostik

Ethik in der Medizin -     

Influence of Bubble Evolution on the Effective Kinetics of Heterogeneously Catalyzed Gas/Liquid Reactions. Part I: Reactions with Gaseous Products

For heterogeneously catalyzed multiphase reactions the formation of bubbles may have an influence on mass and heat transfer as well as on the effective reaction rate. This first of two contributions deals with the Ni‐catalyzed decomposition of H₂O₂, which was used as a model system for an (almost) isothermal reaction with a gaseous product. (In part II the strongly exothermic hydrogenation of hexene will be analyzed, where gas/vapor bubbles may be generated by overheating of the catalyst.) The discharge of O₂ bubbles formed by decomposition of H₂O₂ enhances the external mass and heat transfer up to one order of magnitude. This is in analogy to the well‐known phenomena during nucleate boiling. The experiments and theoretical considerations also show that the internal mass transfer depends on the intensity of the reaction and thus on the H₂O₂ concentration, which is in contradiction to the classical Thiele approach. This discrepancy could be explained by a modified model that takes the formation of bubbles into account.     

Brain death: neuropathological findings and forensic implications

'Brain death' is defined pathophysiologically as intracranial circulatory arrest. The morphological features of brain death include cerebral edema, absence of reactive changes, and--after an interval of 15-36 h--the morphological hallmarks of respirator brain: edema, global softening of the brain, dusky discoloration of the gray matter, and often necrotic and sloughing tonsillar herniations. The following implications of brain death for forensic medicine are discussed: discriminating between respirator and autolytic brain, declaration of death, determining the time of brain death versus the time of the traumatic event leading to brain death, and neuropathological control of the clinical diagnosis of brain death. These issues are elucidated and their bearing on forensic practice is illustrated by several real-life situations. Thus, neuropathological examination in the case of clinically diagnosed brain death is--without doubt--necessary in order to answer several questions often or regularly expected.     

Effects of the combinations propofol/alfentanil and midazolam/fentanyl on blood pressure and contact phase system during coronary surgery

Perioperative haemodynamic changes leading to severe circulatory problems during open-heart surgery still represent dreaded complications. The aim of this study was to examine the relationship between the use of applied anaesthetic agents and alterations of the contact phase of the intrinsic blood-clotting system, as changes within the kallikrein-kinin system can lead to a fall in blood pressure. In a randomized study, parameters of the kallikrein-kinin system, coagulation and fibrinolysis were determined for 36 patients with aortocoronary bypass operations. The patients had been given either midazolam/fentanyl or propofol/alfentanil to maintain anaesthesia. Perioperative blood pressure values were registered at seven fixed points. The measured values of the factor XIIa-like activity and the kallikrein-like activity suggested a higher activation of the contact phase, when propofol/alfentanil was given. From the start of the extracorporeal circulation (ECC) to the end of the operation, the kallikrein-like activities in the propofol/alfentanil group were significantly higher than those of the midazolam/fentanyl group. Also, the results of the kallikrein inhibition capacity and the indicators of fibrinolysis (t-PA and D-dimers) indicate a stronger activation of the contact phase--at least at the beginning of recirculation--and as a result of it, a stronger fibrinolysis within the propofol/alfentanil group. In addition, the hypotensive side-effects differed significantly between the two groups. Patients receiving propofol/alfentanil needed the triple amount of antihypotonicum to maintain the mean arterial blood pressure above 75 mmHg. With the results of this study, a correlation between the application of propofol/alfentanil, contact phase activation, with activation of the kallikrein-kinin-bradykinin system and the observed hypotension, can be presumed.     

Die Zündgrenzen des 87-Oktan-Benzins

Ohne Zusammenfassung     

Multiblend JET A-1 in Practice: Results of an R&D Project on Synthetic Paraffinic Kerosenes

The research and demonstration project, DEMO-SPK, a model project under the German Mobility and Fuel Strategy (MFS), investigated the use of renewable kerosene at the Leipzig/Halle airport. Its primary goal was to examine and verify the behavior of blends consisting of several types of renewable kerosene and fossil JET A-1, under the realistic supply conditions of a major airport. The project demonstrated that the supply chain for multiblend JET A-1 was technically feasible and that the fuel could be used without requiring any changes in the normal operating procedures. The project also confirmed that the use of multiblend JET A-1 resulted in a 30–60% reduction in particulate emissions for ground operations and a reduction in CO₂ equivalents, compared with pure fossil JET A-1.     

Axonal injury--a diagnostic tool in forensic neuropathology? A review

Radionuclide tracers of heavy metals (59Fe, 60Co, 65Zn, 75Se, 85Sr, 134Cs and 203Hg) representing potential contamination from nuclear power plants, industry and agriculture were added to separate basins of Lake 226, Experimental Lakes Area, northwestern Ontario. The two basins were part of a eutrophication experiment and differed in their trophic status; the north basin (L226N) was eutrophic whereas the south basin (L226S) was mesotrophic. Our objective was to determine the uptake of the radionuclides by biota and the effect of lake trophic status on their bioaccumulation. The trophic status of the lakes did not appear to have a marked effect on the accumulation of radionuclides by the biota. This may have been because of a mid-summer leakage of nutrients between the basins which enhanced primary production in L226S, because there is a time lag between primary production and the availability of the radionuclides to the fishes or because trophic status does not affect the uptake of at least some of these radionuclides. However, there was a tendency for faster uptake of the radionuclides in L226N by fish than L226S, but the differences were not significant. Concentrations in the biota generally decreased in the order: fathead minnow > pearl dace > tadpoles > slimy sculpin > leeches. Concentrations in biota generally decreased in the order. 65Zn > 203Hg > 75Se > 134Cs > 60Co > 85Sr = 59Fe. Cobalt-60 concentrations in tadpoles were greater than in the other biota. Radionuclide concentrations in the tissues of lake whitefish indicated that uptake was predominantly from food. Radionuclide concentrations were usually higher in the posterior gut, liver and kidney than in other tissues, whereas body burdens were generally high in the muscle for 75Se, 134Cs and 203Hg; kidney and gut for 60Co; and bone for 65Zn and 75Se. Mercury-203 burdens were also high in the bone and gut.