Angiographic findings and clinical implications of persistent primitive hypoglossal artery

BACKGROUND: The primitive hypoglossal artery (PHA) is a rare vascular anomaly, which belongs to the group of carotid-basilar anastomosis that may occur in adults. CASE PRESENTATION: Herein is presented a case of a patient with a PHA, who had undergone a cerebral angiography due to investigation of subarachnoid hemorrhage. Additionally, the diagnostic alternatives for detection and assessment of PHA and the spectrum of diseases related to its presence are discussed. CONCLUSIONS: The presence of a persistent PHA can be recognized as an incidental finding in a cerebral angiography without any other clinical implication or may be associated with certain clinical entities such as aneurysm formation and atherosclerotic disease

Sorptionseigenschaften von nanokristallinen Metallhydriden fuer die Wasserstoffspeicherung

For the utilisation of hydrogen in emission-free automobiles new nanostructured Mg-based metal hydrides were developed. These materials show significantly faster absorption and desorption kinetics, which can be even further enhanced by additions of suitable catalysts. Contrary to conventional magnesium powder, hydrogenation at room temperature is demonstrated for the first time. During dehydrogenation at 250 C a desorption rate of 3 to 8 kW/kg with a capacity of 2.5 kWh/kg is achieved, that fulfills the technical requirements for automobile application. (orig.)Im Hinblick auf den Einsatz von Wasserstoff in emissionsfreien Kraftfahrzeugen wurden neuartige nanostrukturierte Metallhydride auf Basis von Magnesium hergestellt. Diese Materialien zeigen eine deutlich schnellere Absorptions- und Desorptionskinetik, die sich durch den Zusatz von geeigneten Katalysatoren noch weiter steigern laesst. Im Gegensatz zu konventionellem Magnesiumpulver konnte erstmals eine Hydrierung bei Raumtemperatur demonstriert werden. Bei der Dehydrierung bei 250 C wird eine Desorptionsrate von 3 bis 8 kW/kg bei einer Kapazitaet von 2,5 kWh/kg erreicht, die die technischen Leistungsanforderungen von Kraftfahrzeugen erfuellt. (orig.)Available from TIB Hannover: RA 3251(2000/29) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Composition determination of semiconductor alloys towards atomic accuracy by HAADF-STEM

This paper presents a comprehensive investigation of an extended method to determine composition of materials by scanning transmission electron microscopy (STEM) high angle annular darkfield (HAADF) images and using complementary multislice simulations. The main point is to understand the theoretical capabilities of the algorithm and address the intrinsic limitations of using STEM HAADF intensities for composition determination. A special focus is the potential of the method regarding single-atom accuracy. All-important experimental parameters are included into the multislice simulations to ensure the best possible fit between simulation and experiment. To demonstrate the capabilities of the extended method, results for three different technical important semiconductor samples are presented. Overall the method shows a high lateral resolution combined with a high accuracy towards single-atom accuracy

Nanocrystalline Mg-based alloys for hydrogen storage

For the future zero-emission vehicle, hydrogen is of great importance as alternative fuel. For both combustion engines as well as fuel cells, the storage of hydrogen in liquid or gaseous form imposes safety problems. Metal hydrides are a safe alternative for H-storage and, in addition, have a higher volumetric energy density. However, so far light-metal hydrides have not been considered competitive because of their rather sluggish sorption kinetics. In contrary, our investigations on nanocrystalline hydrides prepared by ball milling show very fast absorption and desorption kinetics within few minutes, thus qualifying hydrides for application. In this paper, we will present sorption kinetics and storage capacity of different Mg-based hydrides. (orig.)4 refs.Available from TIB Hannover: RA 3251(98/E/9) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman