42 research outputs found
Probing the shape of atoms in real space
The structure of single atoms in real space is investigated by scanning
tunneling microscopy. Very high resolution is possible by a dramatic reduction
of the tip-sample distance. The instabilities which are normally encountered
when using small tip-sample distances are avoided by oscillating the tip of the
scanning tunneling microscope vertically with respect to the sample. The
surface atoms of Si(111)-(7 x 7) with their well-known electronic configuration
are used to image individual samarium, cobalt, iron and silicon atoms. The
resulting images resemble the charge density corresponding to 4f, 3d and 3p
atomic orbitals.Comment: Submitted to Phys. Rev. B, 17 pages, 7 figure
Stimulation of the Sphenopalatine Ganglion Induces Reperfusion and Blood-Brain Barrier Protection in the Photothrombotic Stroke Model
The treatment of stroke remains a challenge. Animal studies showing that electrical stimulation of the sphenopalatine ganglion (SPG) exerts beneficial effects in the treatment of stroke have led to the initiation of clinical studies. However, the detailed effects of SPG stimulation on the injured brain are not known.The effect of acute SPG stimulation was studied by direct vascular imaging, fluorescent angiography and laser Doppler flowmetry in the sensory motor cortex of the anaesthetized rat. Focal cerebral ischemia was induced by the rose bengal (RB) photothrombosis method. In chronic experiments, SPG stimulation, starting 15 min or 24 h after photothrombosis, was given for 3 h per day on four consecutive days. Structural damage was assessed using histological and immunohistochemical methods. Cortical functions were assessed by quantitative analysis of epidural electro-corticographic (ECoG) activity continuously recorded in behaving animals.Stimulation induced intensity- and duration-dependent vasodilation and increased cerebral blood flow in both healthy and photothrombotic brains. In SPG-stimulated rats both blood brain-barrier (BBB) opening, pathological brain activity and lesion volume were attenuated compared to untreated stroke animals, with no apparent difference in the glial response surrounding the necrotic lesion.SPG-stimulation in rats induces vasodilation of cortical arterioles, partial reperfusion of the ischemic lesion, and normalization of brain functions with reduced BBB dysfunction and stroke volume. These findings support the potential therapeutic effect of SPG stimulation in focal cerebral ischemia even when applied 24 h after stroke onset and thus may extend the therapeutic window of currently administered stroke medications
Abstracts from the 20th International Symposium on Signal Transduction at the Blood-Brain Barriers
https://deepblue.lib.umich.edu/bitstream/2027.42/138963/1/12987_2017_Article_71.pd
Fremdstoffmetabolisierende Enzyme in Tetranychus urticae (Koch)
Available from TIB Hannover: DW 7630 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
Bestimmung des Wirkstoffes Fenoxycarb in Holz mittels HochdruckflĂŒssigchromatographie
International audienceFenoxycarb ist ein insektizider Wirkstoff, der wegen seiner hormonĂ€hnlichen Wirkung in sehr geringen Konzentrationen in Holzschutzmitteln eingesetzt werden kann. Das hat zur Folge, dass aus Extrakten von behandeltem Holz relativ geringe Fenoxycarb-Mengen vor dem Hintergrund ebenfalls extrahierter Holzinhaltsstoffe zu bestimmen sind. In Vergleichsanalysen verschiedener Laboratorien wurde gezeigt, dass Fenoxycarb durch Methanol mit hoher Ausbeute aus Holz extrahierbar ist und in den Extrakten durch HochdruckflĂŒssigchromatographie in Kopplung mit UV-Detektion bestimmt werden kann. Fenoxycarb-Konzentrationen im unteren Bereich der erforderlichen Einbringmengen können mit dem erprobten Verfahren nur nach zusĂ€tzlicher Probenaufarbeitung bestimmt werden. Bedingt durch schwer auswertbare Chromatogramme sind die Abweichungen der Ergebnisse zwischen verschiedenen Laboratorien relativ hoch
Zustandsanalyse und Langzeitveraenderungen des Oekosystems Greifswalder Bodden Abschlussbericht
Available from TIB Hannover: RN 8908(95-003) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Umwelt, Naturschutz und Reaktorsicherheit, Bonn (Germany)DEGerman