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  • 1
    Electronic Resource
    Electronic Resource
    A comparison by means of calorimetry of solid state interdiffusion reactions in Ni/Zr and Ni/Ti composites (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 1910-1913 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated solid state amorphization reactions in mechanically deformed composites in both the Ni-Ti system and the Ni-Zr system. The growth of amorphous material in our Ni/Ti composites is apparently facilitated by the relatively large degree of disorder induced in the metal layers by the mechanical deformation process. The growth of amorphous material is slower in Ni/Ti composites than in Ni/Zr composites, while we found similar kinetic constraints on the formation of equilibrium compounds in both systems. Thus the maximum thickness of amorphous Ni-Ti layers was an order of magnitude less than the 1000-A(ring) layers grown in the Ni-Zr system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346581
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Introducing fluorine-18 fluoromisonidazole positron emission tomography for the localisation and quantification of pig liver hypoxia (1999)
    Springer
    European journal of nuclear medicine 26 (1999), S. 95-109 
    Details
    ISSN: 1619-7089
    Keywords: Key words: Liver cell hypoxia ; Nitroimidazole imaging ; Fluorine-18 fluoromisonidazole ; Positron emission tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Fluorine-18 labelled fluoromisonidazole ([18F]FMISO) has been shown to accumulate in hypoxic tissue in inverse proportion to tissue oxygenation. In order to evaluate the potential of [18F]FMISO as a possible positron emission tomography (PET) tracer for imaging of liver tissue hypoxia, we measured the [18F]FMISO uptake in 13 domestic pigs using dynamic PET scanning. Hypoxia was induced by segmental arterial hepatic occlusion. During the experimental procedure the fractional concentration of inspired oxygen (FiO2) was set to 0.67 in group A (n=6) and to 0.21 in group B (n=7) animals. Before and after arterial occlusion, the partial pressure of O2 in tissue (TPO2) and the arterial blood flow were determined in normal flow and flow-impaired liver segments. Standardised uptake values [SUV=kBq tissue (in g) / body weight (in kg) × injected dose (in kBq)] for [18F]FMISO were calculated from PET images obtained 3 hours after injection of about 10 MBq/kg body weight [18F]FMISO. Immediately before PET scanning, the mean arterial blood flow was significantly decreased in arterially occluded segments [group A: 0.41 (0.32–0.52); group B: 0.24 (0.16–0.33) ml min–1 g–1] compared with normal flow segments [group A: 1.05 (0.76–1.46); group B: 1.14 (0.83–1.57) ml min–1 g–1; geometric mean (95% confidence limits); P〈0.001 for both groups]. After PET scanning, the TPO2 of occluded segments (group A: 5.1 (4.1–6.4); group B: 3.5 (2.6–4.9) mmHg] was significantly decreased compared with normal flow segments [group A: 26.4 (21.2–33.0); group B: 18.2 (13.3–25.1) mmHg; P〈0.001 for both groups]. During the 3-h PET scan, the mean [18F]FMISO SUV determined in occluded segments increased significantly to 3.84 (3.12–4.72) in group A and 5.7 (4.71–6.9) in group B, while the SUV remained unchanged in corresponding normal liver tissue [group A: 1.4 (1.14–1.71); group B: 1.31 (1.09–1.57); P〈0.001 for both groups]. Regardless of ventilation conditions, a significant inverse exponential relationship was found between the TPO2 and the [18F]FMISO SUV (r 2=0.88, P〈0.001). Our results suggest that because tracer delivery to hypoxic tissues was maintained by the portal circulation, the [18F]FMISO accumulation in the liver was found to be directly related to the severity of tissue hypoxia. Thus, [18F]FMISO PET allows in vivo quantification of pig liver hypoxia using simple SUV analysis as long as tracer delivery is not critically reduced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002590050365
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  • 3
    Electronic Resource
    Electronic Resource
    N-[11C]methyl-3,4-methylenedioxyamphetamine (Ecstasy) and 2-methyl-N-[11C]methyl-4,5-methylenedioxyamphetamine: Synthesis and biodistribution studies (1999)
    Springer
    Journal of radioanalytical and nuclear chemistry 240 (1999), S. 535-540 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In order to evaluate the neurobiological mechanism causing the psychogenic effects of methylenedioxy-derivatives of amphetamine, the carbon-11 labeled analogues of 3,4-methylenedioxymethamphetamine (MDMA),2 and 2,N-dimethyl-4,5-methylenedioxyamphetamine (MADAM-6)4 were prepared for application in in-vivo PET studies by methylation of 3,4-methylenedioxyamphetamine (MDA)1 and 2-methyl-4,5-methylenedioxyamphetamine3 with [11C]CH3I. The radiochemical yield was determined in dependence on time, temperature and amount of precursor. The best conditions for a fast labeling reaction with carbon-11 on a preparative scale were found to be a reaction time of 10 min using 1 mg of the corresponding dimethyl-precursors1 or3, thus obtaining radiochemical yields of 60% (based on produced [11C]CH3I). Biodistribution studies were performed in rats, a high brain to blood ratio of 7.5 was observed for [11C]MDMA in contrast to a ratio of 3.7 for [11C]MADAM-6.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02349410
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  • 4
    Electronic Resource
    Electronic Resource
    Preparation of [18F]fluoromisonidazole by nucleophilic substitution on THP-protected precursor: Yield dependence on reaction parameters (1999)
    Springer
    Journal of radioanalytical and nuclear chemistry 240 (1999), S. 925-927 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The dependence of the radiochemical yield of [18F]fluoromisonidazole (1) on different reaction parameters such as reaction time, temperature and amount of precursor was investigated for the nucleophilic substitution of tosylate by [18F]fluoride and subsequent hydrolysis of the protecting group on 1-(2′-nitro-1′-imidazolyl)-2-O-tetrahydropyranyl-3-O-toluenesulfonylpropanediol as the precursor molecule (2). Highest yields (86%±6%) were obtained using 10 mg (2) at 100°C for 10 minutes, whereas both at 80 and 120°C the yields were lower (46%±11% and 29%±14%, respectively). A rapid decrease of the yield was observed when the reaction time exceeded 15 minutes, i.e., at 100°C using 5 mg (2) the radiochemical yield decreased from 61%±8% at 15 minutes to 18%±10% at 60 minutes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02349874
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