Articles you may be interested inDistinguishing triplet energy transfer and trap-assisted recombination in multi-color organic light-emitting diode with an ultrathin phosphorescent emissive layer Determination of traps in poly(p-phenylene vinylene) light emitting diodes by charge-based deep level transient spectroscopyWe investigated electroluminescent ͑EL͒ characteristics of single-layer organic light emitting diodes ͑SOLEDs͒. Our SOLED devices are composed of an inert polymer as a binder, in which hole transport molecules, emissive electron transport molecules ͑ETMs͒, and highly fluorescent dopants as luminescent centers are dispersed. We examined two typical dopants: rubrene and coumarin 6. These exhibited different charge carrier recombination and emission mechanisms. The dopant concentration dependence of the current density-voltage-luminance relationships clearly showed the importance of carrier trapping by dopant molecules for obtaining high luminance. When the dopant was rubrene, we observed that charge carriers were well trapped by the dopant molecule. This means that direct recombination of holes and electrons occurred on the dopant molecules and trapping significantly enhanced the external EL quantum efficiency ⌽ EL . For coumarin 6, on the other hand, we observed that charge carriers primarily recombined at the emissive ETMs and that the energy transfer from the host to the guest coumarin 6 molecule dominated the EL process. A comparison of these distinct processes revealed that carrier trapping by dopant molecules was necessary to enhance ⌽ EL in SOLED devices. In our best SOLED device with rubrene as a dopant, we measured luminance of 2800 cd/m 2 at Jϭ100 mA/cm 2 , which corresponds to ⌽ EL ϭ0.85%.

In 10 years after H. pylori eradication, atrophy at all sites and IM in the lesser curvature of the corpus gradually and significantly decreased. These results suggest that the improvement of gastric atrophy and IM might have association with the reduction of gastric cancer occurrence.

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Magnetic susceptibility and the magnetization process have been measured in Ba 3 Mn 2 O 8 polycrystal. In this compound the magnetic manganese ion exists as Mn 5+ in a tetrahedral environment, and thus the magnetic interaction can be described by an S = 1 Heisenberg model. The ground state was found to be a spin singlet with an excitation gap Δ/k B = 11.2 K . Magnetization plateaus were observed at zero and at half of the saturation magnetization. These results indicate that the present system can be represented by a coupled antiferromagnetic dimer model. 2) The space group of this compound is trigonal R3m. The lattice constants are a = 5.71Å and c = 21.44Å. Mn 5+ ions are located at the center of tetrahedra of O 2− ions. All of the Mn 5+ sites are equivalent. The Mn 5+ ions form double-layered triangular lattices in the basal plane, which are stacked along the c-axis with a periodicity of three, as shown in Fig. 1. If the exchange interactions J 1 and J 2 are antiferromagnetic, they can produce spin frustration. Therefore, Ba 3 Mn 2 O 8 is an interesting system from both chemical and physical points of view.The precise magnetic measurements of Ba 3 Mn 2 O 8 have not been reported so far. In this paper, we present the results of magnetic susceptibility and high-field magnetization measurements for purified Ba 3 Mn 2 O 8 polycrystal. As shown later, a gapped ground state is intrinsic to the present system. §2. Experimental Procedures Ba 3 Mn 2 O 8 polycrystal was prepared according to the chemical reactionIn this reaction, Mn 4+ is oxidized to Mn 5+ . Reagentgrade BaCO 3 and MnO 2 were mixed in stoichiometric quantities, and calcined at 900• C for 30 hours in air. A * E-mail: uchida@lee.phys.titech.ac.jp. greenish material obtained was examined by X-ray powder diffraction, and the findings were compared with reported data.3) Although the diffraction pattern obtained has the features peculiar to Ba 3 Mn 2 O 8 , many unsystematic peaks due to impurities were observed. Magnetic susceptibility measurements of this material revealed the existence of a small ferromagnetic impurity phase with a transition temperature T c = 43 K, which seems to be 1790 maintain attribution to the author(s) and the title of the article, journal citation, and DOI.

Background and Aim:Helicobacter pylori has been shown to cause atrophic gastritis and intestinal metaplasia (IM), both of which are precancerous lesions. To clarify the mechanism by which H. pylori eradication prevents gastric cancer, we monitored atrophy and IM improvement in gastric mucosa over a long period after H. pylori eradication. Methods: We monitored 118 patients (72 males, 46 females; mean age 61.3 ± 5.1 years) for a mean of 8.6 years (range 5–13) after successful H. pylori eradication. Biopsy specimens were taken from the greater curvatures of the antrum (A2) and the corpus (B2). Results: Atrophy was significantly decreased in patients with successful H. pylori eradication, both at A2 (from 1.60 ± 0.09 to 1.02 ± 0.08; p < 0.001) and B2 (from 0.71 ± 0.10 to 0.02 ± 0.02; p < 0.001), and IM score was significantly decreased at B2 (from 0.17 ± 0.12 to 0.00 ± 0.00; p < 0.05), but not at A2 (from 0.60 ± 0.11 to 0.43 ± 0.09; p = NS). In patients without successful eradication, however, there were no differences in scores over time. Before eradication, IM score was significantly higher in males than in females, both at A2 (0.81 ± 0.12 vs. 0.25 ± 0.10; p < 0.05) and B2 (0.32 ± 0.08 vs. 0.07 ± 0.04; p < 0.05). Conclusion: We were able to monitor the gastric mucosa for a mean of 8.6 years after H. pylori eradication, the longest period reported to date. Significant improvements in gastric atrophy and IM after H. pylori eradication may decrease the risk of gastric cancer.