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Lattice site location of ion-implanted 8Li in Silicon Carbide (2002)

Virdis, S. ; Vetter, U. ; Ronning, C. ; [et al.]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 91 (2002), S. 1046-1052

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ISSN: 1089-7550

Source: AIP Digital Archive

Topics: Physics

Notes: The lattice sites of ion-implanted Li atoms in 6H-, 4H-, and 3C-SiC were studied. Radioactive 8Li ions (t1/2=0.84 s) were implanted with 60 keV into the crystalline SiC samples, and the channeling and blocking effects of 1.6 MeV alpha particles emitted in the decay were measured to determine the Li lattice sites. The alpha emission channeling spectra measured along different crystallographic directions reveal that Li occupies mainly interstitial sites with tetrahedral symmetry, centered along the c-axis atom rows in the hexagonal lattices. In the cubic 3C-SiC structure, Li is located on tetrahedral interstitial sites as well. For 6H-SiC, the implantation temperature was varied between 200 and 823 K without observing significant changes in the emission channeling spectra. Thus, Li diffusion or Li defect interaction resulting in a lattice site change does not occur in this temperature regime. © 2002 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.1425442

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Increased CNS uptake and enhanced antinociception of morphine-6-glucuronide in rats after inhibition of P-glycoprotein (2002)

Lötsch, Jörn ; Schmidt, Rodolfo ; Vetter, Gregor ; [et al.]

Oxford, UK : Blackwell Science Ltd

Journal of neurochemistry 83 (2002), S. 0

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ISSN: 1471-4159

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Medicine

Notes: Morphine-6-glucuronide (M6G) is a substrate of P-glycoprotein (P-gp), which forms an outward transporter at the blood–brain barrier. Inhibition of P-gp may therefore be expected to cause increased CNS uptake of M6G. We directly assessed the spinal concentrations of M6G and its antinociceptive effects in rats following pharmacological inhibition of P-gp. Spinal cord tissue concentrations of M6G were assessed by microdialysis with probes transversally implanted through the dorsal horns of the spinal cord at level L4. Ten rats received M6G intravenously (0.018 mg/kg loading dose plus 0.00115 mg/kg/min for an 8-h infusion), five of them together with PSC833 to inhibit P-gp (32-h infusion, starting 24 h before the addition of M6G). Antinociceptive effects were explored by means of formalin tests. After having obtained evidence for enhanced CNS uptake and antinociception of M6G in the presence of PSC833, additional behavioural experiments were performed in another 32 rats to assess the dose dependency of the antinociceptive effects of M6G either with or without PSC833 in comparison with both PSC833 alone and placebo. Inhibition of P-gp increased the M6G concentrations in the spinal cord approximately three-fold whereas the plasma concentrations were increased only by a factor of 1.4, which resulted in a more than doubled spinal cord/plasma concentration ratio (from 0.08 ± 0.03 for M6G alone to 0.17 ± 0.08 for M6G plus PSC833). Antinociceptive effects of M6G were significantly enhanced by inhibition of P-gp. Inhibition of P-gp alters the transport of M6G across the blood–brain barrier, resulting in enhanced spinal cord uptake and enhanced antinociception.