By substituting Na+ with smaller Li+ ions within NaYF4 lattice, we expected to induce distortions in order to prevent the concentration quenching process, which is responsible for decrease of the luminescence intensity. The results indicated that the substitution of sodium ions by Li+ did not enhance Tm3+ up-conversion emission significantly in alpha-NaYF4:Yb3+/Tm3+. However, the influence of lithium ions on luminescence was not entirely the same in the case of 2% Tm3+ and 0.1%

Tm3+ doped samples. The slight up-conversion intensity enhancement in the case of samples doped with 2% Tm3+ could result from the increase in the crystallites size and changes in the surface to volume ratio. The observed increase in lattice parameter and thus the increased distance between

buy PF-6463922 thulium ions in the lattice might also result in breaking apart of pairs responsible for cross-relaxation processes. Interestingly, in the 0.1% Tm3+ co-doped www.selleckchem.com/products/BI-2536.html samples, initial luminescence intensity decrease followed by increase correlated with Li+ substitution was observed. Due to the existence of two different sites for incorporation of lithium ions into the host lattice, the changes in lattice parameters and resulting optical properties are not straightforward functions of variable amount of Li+. (C) 2013 Elsevier B.V. All rights reserved.”
“Three variants of the composite transposon Tn10 were extracted from transferable plasmids of fish farm bacteria. These variants were identical in insertions with IS10, but differed in another class I transposon insertion and a region

find more of homologous recombination downstream of tetB.”
“Epidemics of dengue have occurred in Greece in 1881, 1889, 1895-1897 and 1910, but the outbreak which has affected this country in 1927-1928 has been of a peculiar severity and geographic extension. More than one million inhabitants were sick and about 1500 died The outbreak extended to the whole Greek territory and evolved in two epidemics waves. The first one occurred during the second half of 1927, was not very extensive and relatively benign. The second wave, explosive, started on July 1928, reached its summit in August and then declined until November During this second part of the outbreak severe clinical events were identified, such as hemorrhagic, neurological or renal disorders, along with infections during pregnancy The mosquito Aedes aegypti was the alone vector of the disease and dengue type I virus was the main etiological agent both in 1927 and 1928. The eventual activity of the dengue type 2 virus and its possible role in the pathogenesis of severe clinical forms of dengue, during 1928, remains unclear Relatively speaking, it is possible to parallel this – historical – outbreak with the recent epidemic episode which appeared in 2007 in the Ravenne’s area in northern Italy.