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  • 1995-1999  (16)
  • bioactivity  (6)
  • Magnetic resonance imaging  (5)
  • methanol synthesis  (5)
  • 1
    Electronic Resource
    Electronic Resource
    Methanol synthesis by the hydrogenation of CO2 over Zn-deposited Cu(111) and Cu(110) surfaces (1995)
    Springer
    Catalysis letters 35 (1995), S. 297-302 
    Details
    ISSN: 1572-879X
    Keywords: methanol synthesis ; Cu(111) ; Cu(110) ; Zn deposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The hydrogenation of CO2 over Zn-deposited Cu(111) and Cu(110) surfaces was performed at 523 K and 18 atm using a high pressure flow reactor combined with XPS apparatus. It was shown that the ZnO x species formed on Cu(111) during reaction directly promoted the methanol synthesis. However, no such promotional effect of the Zn was observed for methanol formation on Cu(110). Thus, Zn on Cu(111) acts as a promoter, while Zn on Cu(110) acts as a poison. The activation energy and the turnover frequency are in fairly good agreement with those obtained for Cu/ZnO powder catalysts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00807186
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  • 2
    Electronic Resource
    Electronic Resource
    Methanol synthesis over a Zn-deposited copper model catalyst (1995)
    Springer
    Catalysis letters 31 (1995), S. 325-331 
    Details
    ISSN: 1572-879X
    Keywords: methanol synthesis ; copper catalyst ; role of ZnO ; XPS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Methanol synthesis by the hydrogenation of CO2 over Zn-deposited polycrystalline Cu was studied using surface science techniques. The Zn sub-monolayer was oxidized by the reaction mixture during the reaction at 523 K, leading to the formation of ZnO species. The kinetic results definitely showed that the ZnO species on the Cu surface promoted the catalytic activity of methanol formation, where the activity of Cu increased by a factor of 6 at the Zn coverage of 0.17. A volcano-shaped curve was obtained for the correlation between the Zn coverage and the catalytic activity, which was very similar to the correlation curve between the oxygen coverage and the specific activity for methanol formation previously obtained for the Cu powder catalysts. The role of ZnO in Cu/ZnO based catalysts was ascribed to the stabilization of Cu+ species by the ZnO moieties on the Cu surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00808596
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The synergy between Cu and ZnO in methanol synthesis catalysts (1996)
    Springer
    Catalysis letters 38 (1996), S. 157-163 
    Details
    ISSN: 1572-879X
    Keywords: methanol synthesis ; Cu/ZnO catalyst ; effect of reduction temperature ; oxygen coverage ; physical mixture ; Cu-Zn alloy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The hydrogenation of CO2 over physically-mixed Cu/SiO2 and ZnO/SiO2 was carried out to clarify the synergetic effect between Cu and ZnO in Cu/ZnO methanol synthesis catalysts. The activity of the physical mixtures significantly increased with increasing reduction temperature in the range of 573–723 K. TEM-EDX results definitely showed that ZnOx moieties migrated from ZnO/SiO2 particles onto the surface of Cu particles when the physical mixtures were reduced at high temperatures above 573 K. Upon the migration of the ZnOx species, the oxygen coverage on the surface of Cu, measured after the hydrogenation of CO2, increased with the reduction temperature. The results clearly showed that the synergetic effect of ZnO in the physical mixtures can be ascribed to the creation of active sites such as Cu+ which the ZnOx moieties stabilize on the Cu surface. Further, XRD results showed that the migrated ZnOx species partly dissolved into the Cu particles to form a Cu—Zn alloy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00806562
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  • 4
    Electronic Resource
    Electronic Resource
    Creation of the active site for methanol synthesis on a Cu/SiO2 catalyst (1997)
    Springer
    Catalysis letters 49 (1997), S. 175-179 
    Details
    ISSN: 1572-879X
    Keywords: methanol synthesis ; Cu/ZnO catalyst ; hydrogenation of CO2 ; role of Zn ; in situ FT-IR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effect of ZnO/SiO2 in a physical mixture of Cu/SiO2 and ZnO/SiO2 on methanol synthesis from CO2 and H2 was studied to clarify the role of ZnO in Cu/ZnO-based catalysts. An active Cu/SiO2 was prepared by the following procedure: the Cu/SiO2 and ZnO/SiO2 catalysts with a different SiO2 particle size were mixed and reduced with H2 at 523-723 K, and the Cu/SiO2 was then separated from the mixture using a sieve. The methanol synthesis activity of the Cu/SiO2 catalyst increased with the reduction temperature and was in fairly good agreement with that previously obtained for the physical mixture of Cu/SiO2 and ZnO/SiO2. These results indicated that the active site for methanol synthesis was created on the Cu/SiO2 upon reduction of the physical mixture with H2. It was also found that ZnO itself had no promotional effect on the methanol synthesis activity except for the role of ZnO to create the active site. The active site created on the Cu/SiO2 catalyst was found not to promote the formation of formate from CO2 and H2 on the Cu surface based on in situ FT-IR measurements. A special formate species unstable at 523 K with an OCO asymmetric peak at ~1585 cm-1 was considered to be adsorbed on the active site.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019069708459
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  • 5
    Electronic Resource
    Electronic Resource
    The effect of ZnO in methanol synthesis catalysts on Cu dispersion and the specific activity (1998)
    Springer
    Catalysis letters 56 (1998), S. 119-124 
    Details
    ISSN: 1572-879X
    Keywords: methanol synthesis ; Cu/ZnO catalyst ; hydrogenation of CO2 ; role of Zn
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effect of ZnO in Cu/ZnO catalysts prepared by the coprecipitation method has been studied using measurements of the surface area of Cu, the specific activity for the methanol synthesis by hydrogenation of CO2, and XRD. Although the Cu surface area increases with increasing ZnO content (0–50 wt%) as is generally known, the specific activity of the Cu/ZnO catalysts with various weight ratios of Cu:ZnO is greater than that of a ZnO-free Cu catalyst. These facts clearly indicate that the role of ZnO in Cu/ZnO catalysts can be ascribed to both increases in the Cu dispersion and the specific activity. The XRD results indicate the formation of a Cu–Zn alloy in the Cu particles of the Cu/ZnO catalysts, leading to the increase in specific activity. It is thus considered that the Cu–Zn surface alloy or a Cu–Zn site is the active site for methanol synthesis in addition to metallic copper atoms that catalyze several hydrogenation steps during the methanol synthesis. Furthermore, the advantage of the coprecipitation method through a precursor of aurichalcite is ascribed to both improvements in the Cu surface area and the specific activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019000927366
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  • 6
    Electronic Resource
    Electronic Resource
    MR arthrography of elbow: evaluation of the ulnar collateral ligament of elbow (1996)
    Springer
    Skeletal radiology 25 (1996), S. 629-634 
    Details
    ISSN: 1432-2161
    Keywords: Key words Elbow ; Ulnar collateral ligament ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Objective. The purpose of this study was to evaluate ulnar collateral ligament (UCL) injury of the elbow in throwing athletes by MRI and MR arthrography. Design. Ten elbows of throwing athletes were examined on both plain MRI and MR saline arthrography and the injuries subsequently surgically proven. Spin-echo (SE) T1-weighted and fast SE T2-weighted coronal images were obtained. Results. The UCL was unclear in all ten cases on T1-weighted MRI. In five cases an avulsion fracture was also found on T1-weighted MRI. On T2-weighted MRI, abnormal high-intensity areas were identified in or around the UCL. On T2-weighted MR arthrography images, extracapsular high-intensity areas, which represent extracapsular leakage, were found in four of five cases with avulsion fracture. At surgery, all these four cases showed avulsion fractures with instability; the other case had a fracture but it was stable and adherent to the humerus. On T2-weighted MR arthrography images, an extracapsular high-intensity area was found in one of the five cases without avulsion fracture. At surgery this patient had a complete tear of the UCL itself. Conclusion. MR arthrography provided additional information for evaluating the degree of UCL injury.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002560050149
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  • 7
    Electronic Resource
    Electronic Resource
    Serial changes on MRI in lumbar disc herniations treated conservatively (1995)
    Springer
    Neuroradiology 37 (1995), S. 378-383 
    Details
    ISSN: 1432-1920
    Keywords: Lumbar disc herniation ; Conservative treatment ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Using serial MRI, we studied 32 patients with herniated lumbar discs, treated conservatively, to clarify the natural history of this condition. MRI was performed in the acute stage, then 6 months and 1 year later. On axial images, the proportion of the cross-sectional area of the spinal canal occupied by the herniated disc was 31.9% on the average on the initial scan, 28.7% 6 months and 25.3% 1 year later. The size of the herniation decreased by more than 20% in 11 patients (34%), by 10–20 % in 8 (28%) and was unchaged in 12 (38%). The height of the disc slightly decreased with time, but there was no significant change in the angle of lordosis in the affected segment. The initial MRI revealed degeneration of all affected discs, and progressive degeneration was observed in 9 patients. The more degenerate the disc and the larger the initial herniation the more the size of the herniated fragment decreased.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00588017
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  • 8
    Electronic Resource
    Electronic Resource
    Spinocerebellar ataxia type 6: MRI of three Japanese patients (1998)
    Springer
    Neuroradiology 40 (1998), S. 222-227 
    Details
    ISSN: 1432-1920
    Keywords: Key words Spinocerebellar ataxia type 6 ; Cerebellar cortical atrophy ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We describe the MRI findings in three Japanese patients with spinocerebellar ataxia type 6 (SCA6) in which a polymorphic CAG repeat was identified in the gene encoding the α1A voltage-dependent P/Q-type Ca2+ channel subunit (CACNL1A4). All showed slowly progressive cerebellar ataxia and mild pyramidal signs. Neuroradiologically, they had moderate cerebellar atrophy, most prominently in the superior vermis, whereas the brain stem appeared to be spared. No abnormal signal intensity was identified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340050571
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  • 9
    Electronic Resource
    Electronic Resource
    Magnetic resonance signal intensity and volume changes after endovascular treatment of intracranial aneurysms causing mass effect (1998)
    Springer
    Neuroradiology 40 (1998), S. 184-188 
    Details
    ISSN: 1432-1920
    Keywords: Key words Aneurysm intracranial ; Magnetic resonance imaging ; Embolisation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To determine when and how intracranial aneurysms causing mass effect change following endovascular treatment, we used MRI to assess patients for 2–3 years after the interventional procedure. Nine patients who had aneurysms compressing the surrounding structures underwent endovascular treatment. Proximal occlusion of the parent artery was performed in seven cases, and in two the aneurysm was embolised with microcoils. After embolisation, signal intensity within aneurysms tended to be high on both T1- and T2-weighted images. When there was rapid reduction in size high-signal zones within aneurysms became isointense or gave low signal on T1-weighted images. On T2-weighted images, isointense or low-signal foci appeared within high-signal areas in the aneurysm, giving mixed intensity. In typical cases, the mean volume of the aneurysm fell to approximately 30 % of its initial value 2–12 months after treatment. After this, no additional reduction was observed. The aneurysms which showed little signal intensity change tended to shrink more slowly and to a lesser degree than the more typical cases. Aneurysms which gave high signal on both T1- and T2-weighted images early following embolisation shrank more quickly than those showing little signal change.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340050565
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  • 10
    Electronic Resource
    Electronic Resource
    Estimation of absorbed dose for 2-[F-18]fluoro-2-deoxy-d- glucose using whole-body positron emission tomography and magnetic resonance imaging (1998)
    Springer
    European journal of nuclear medicine 25 (1998), S. 565-574 
    Details
    ISSN: 1619-7089
    Keywords: Key words: Absorbed Dose ; S-value ; MIRD phantom ; Whole-body positron emission tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The purpose of this study was to measure the cumulated activity and absorbed dose in organs after intravenous administration of 2-[F-18]fluoro-2-deoxy-d-glucose (18F-FDG) using whole-body positron emission tomography (PET) and magnetic resonance imaging (MRI). Whole-body dynamic emission scans for 18F-FDG were performed in six normal volunteers after transmission scans. The total activity of a source organ was obtained from the activity concentration of the organ measured by whole-body PET and the volume of that organ measured by whole-body T1-weighted MRI. The cumulated activity of each source organ was calculated from the time-activity curve. Absorbed doses to the individuals were estimated by the MIRD (medical internal radiation dosimetry) method using S-values adjusted to the individuals. Another calculation of cumulated activities and absorbed doses was performed using the organ volumes from the MIRD phantom and the ”Japanese reference man” to investigate the discrepancy of actual individual results against the phantom results. The cumulated activities of 18 source organs were calculated, and absorbed doses of 27 target organs estimated. Among the target organs, bladder wall, brain and kidney received the highest doses for the above three sets of organ volumes. Using measured individual organ volumes, the average absorbed doses for those organs were found to be 3.1×10–1, 3.7×10–2 and 2.8×10–2 mGy/MBq, respectively. The mean effective doses in this study for individuals of average body weight (64.5 kg) and the MIRD phantom of 70 kg were the same, i.e. 2.9×10–2 mSv/MBq, while for the Japanese reference man of 60 kg the effective dose was 2.1×10–2 mSv/MBq. The results for measured organ volumes derived from MRI were comparable to those obtained for organ volumes from the MIRD phantom. Although this study considered 18F-FDG, combined use of whole-body PET and MRI might be quite effective for improving the accuracy of estimations of the cumulated activity and absorbed dose of positron-labelled radiopharmaceuticals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002590050257
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    Paper (German National Licenses)
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