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411.
412.
No fumarase activity could be found in whole cells or in cell-free crude extracts from Leuconostoc mesenteroides or Lactobacillus curvatus. The degradation of l-malate-4-14C by these organisms yielded more than 95% of the label as 14CO2. It is therefore recommended that these organisms, rather than Lactobacillus plantarum, should be used in the determination of isotope distribution in l-malate-14C, since L. plantarum exhibits a significant fumarase activity and thus randomizes malate prior to the decarboxylation of this substance by the malolactic enzyme. 相似文献
413.
Hong Yu Wenwen Zi Shi Lan Shucai Gan Haifeng Zou Xuechun Xu Guangyan Hong 《Luminescence》2013,28(5):679-684
Sr3MgSi2O8:Ce3+, Dy3+ phosphors were prepared by a solid‐state reaction technique and the photoluminescence properties were investigated. The emission spectra show not only a band due to Ce3+ ions (403 nm) but also as a band due to Dy3+ ions (480, 575 nm) (UV light excitation). The photoluminescence properties reveal that effective energy transfer occurs in Ce3+/Dy3+ co‐doped Sr3MgSi2O8 phosphors, and the co‐doping of Ce3+ could enhance the emission intensity of Dy3+ to a certain extent by transferring its energy to Dy3+. The Ce3+/Dy3+ energy transfer was investigated by emission/excitation spectra, and photoluminescence decay behaviors. In Sr2.94MgSi2O8:0.01Ce3+, 0.05Dy3+ phosphors, the fluorescence lifetime of Dy3+ (from 3.35 to 27.59 ns) is increased whereas that of Ce3+ is greatly decreased (from 43.59 to 13.55 ns), and this provides indirect evidence of the Ce3+ to Dy3+ energy transfer. The varied emitted color of Sr3MgSi2O8:Ce3+, Dy3+ phosphors from blue to white were achieved by altering the concentration ratio of Ce3+ and Dy3+. These results indicate Sr3MgSi2O8:Ce3+, Dy3+ may be as a candidate phosphor for white light‐emitting diodes. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
414.
Urinary iodide and iodine in drinking water were determined in 318 healthy children aged 0 to 18 yr living in Izmir and environmental
rural and urban areas in the western part of Turkey. The method is based on substochiometric isotope dilution analysis. Iodide
was precipitated by substoichiometric amounts of AgNO3. Iodide-131 was used as a tracer. Electrophoresis was performed to separate Ag131I from excess131I-. The Ag131I zone was cut off the electrophoresis paper and counted with a Nal(Tl) scintillation counter. Count rates were plotted versus
added KI concentrations. The unknown iodide amount was found by using these linear plots. Iodide concentration ranges were
within 1.8 –100.45 Μg/L in the analyzed drinking water samples. The mean value was 44.14 ±17.33 Μg/L and the median was 58.08
Μg/L. Urinary iodide concentration ranges were 0.22 –142.22 Μg/L. The median of the distribution was 37.71 Μg/L and the mean
was 40.30 ±24.05 Μg/L. The results show that the examined area suffers moderate iodine deficiency. 相似文献