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  • 1
    Electronic Resource
    Electronic Resource
    Transport characteristics of paraquat across rat intestinal brush-border membrane (1993)
    Springer
    Archives of toxicology 67 (1993), S. 262-267 
    Details
    ISSN: 1432-0738
    Keywords: Paraquat ; Absorption ; Brush-border membrane ; Specialized transport system ; Rat intestine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The mechanism of absorption of paraquat, which is a type of quaternary ammonium compound (QAC), was studied using rat intestinal loops and brushborder membrane vesicles. Approximately 47% and 37% of radioactively labeled paraquat injected into jejunal and ileal loops disappeared, respectively, after 60 min. Since only a small amount of radioactivity was detected in the mucosal fraction, most of the paraquat that disappeared from the intestinal lumen was considered to have been carried away by the bloodstream, indicating that paraquat absorption was greater than expected. In spite of its low lipid solubility, the uptake of paraquat by brush-border membrane vesicles reflected smooth penetration into the intravesicular space rather than binding to the membrane. According to the increase in extravesicular paraquat concentration, paraquat uptake in the early stage was saturable. Moreover, early paraquat uptake was significantly inhibited by structurally-related QACs such as tetramethylammonium and choline, but not by an endogenous dicationic amine (putrescine). On the other hand, inside-negative membrane potential had no significant effect on the time course of paraquat uptake. From these results, it is suggested that paraquat is absorbed through a specialized mechanism associated with the carrier-mediated transport system for choline on the brush-border membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01974345
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  • 2
    Electronic Resource
    Electronic Resource
    Seed-set and pollen–stigma compatibility in Leymus chinensis (2004)
    Oxford, UK : Blackwell Science Ltd
    Grass and forage science 59 (2004), S. 0 
    Details
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Chinese leymus [Leymus chinensis (Trin.) Tzvel.] is an important forage distributed in East Asia. The seed-set rates and the pollen–stigma compatibility in six populations were investigated in 2001. Proportionately seed-set ranged from 0·065 to 0·567 under open pollination and 0·0056 to 0·0426 under self-pollination. The former is significantly higher than the latter in each population. Microscopic observations showed that proportionately only 0·0551 to 0·1167 of self-pollinated pollen grains were compatible but most cross-pollinated pollen grains were compatible. The tubes of most incompatible pollen grains aborted upon entering into the stigmas. Among the six populations, there was a significant correlation between seed-set under open pollination and the compatible pollen rates under cross-pollination. These results suggest that Chinese leymus is a self-incompatible species, and the compatibility of pollen and stigma might be one of the factors influencing seed-set in natural conditions. This information will be useful for future breeding efforts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.2004.00419.x
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  • 3
    Electronic Resource
    Electronic Resource
    On the interface states generated under different stress conditions (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 3092-3094 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: After dry oxidation and when annealing in a hydrogen environment is carefully avoided, the energy distribution of interface states has two peaks, one in the lower and one in the upper half of the silicon band gap. Following hydrogen passivation, however, the interface states created by irradiation or electron injection typically have only one peak in the upper half of the gap. This letter investigates how to generate a double peak distribution by electrical stress and we attempt to link the distribution with the generation mechanism. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1416168
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  • 4
    Electronic Resource
    Electronic Resource
    Preparation and characterization of rare earth orthovanadates for propane oxidative dehydrogenation (1996)
    Springer
    Catalysis letters 37 (1996), S. 241-246 
    Details
    ISSN: 1572-879X
    Keywords: rare earth orthovanadates ; citrate method ; propane oxidative dehydrogenation ; redox property
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract High purity rare earth orthovanadates (REVO4), YVO4, LaVO4, CeVO4, NdVO4, SmVO4 and EuVO4, were prepared by the citrate method. XRD, FT-IR, LRS and TPR techniques were employed to characterize these orthovanadates. The catalytic performance of SmVO4, LaVO4 and YVO4 in the oxidative dehydrogenation of propane can compete with that of Mg3V2O8. The selectivity of propene over CeVO4, NdVO4 and EuVO4 was relatively lower. The correlation between the reducibility and the selectivity of the catalysts implied that the V4+/V3+ couple might be involved in the dehydrogenation process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00807761
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  • 5
    Electronic Resource
    Electronic Resource
    The oxidative coupling of methane and the activation of molecular O2 on CeO2/BaF2 (1994)
    Springer
    Catalysis letters 29 (1994), S. 177-188 
    Details
    ISSN: 1572-879X
    Keywords: OCM ; metal oxide-fluoride ; electron-enriched lattice oxygen ; quasi-free electrons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract CeO2/BaF2 was used as the catalyst for the oxidative coupling of methane (OCM). At 800°C and CH4∶O2=2.7∶1,CH4 conversion of 34% with C2 hydrocarbon selectivity of 54.3% was obtained. XRD measurement showed that partial anion (O2−,F−) and/or cation (Ce4+,Ba2+) exchange between CeO2 and BaF2 lattices occurred. ESR study showed that O− species existed on degassed catalyst. XPS study revealed that, when BaF2 was added to CeO2, the binding energy of Be 3d5/2 was 2.2 eV lower than that in CeO2, and the “electron-enriched lattice oxygen” species was detected. XPS, ESR and Raman study showed that, under O2 adsorbing conditions, O 2 2− and O − 2 species were detected on CeO2/BaF2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00814264
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    Paper (German National Licenses)
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