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Recent epidemiological and intervention studies have suggested that polyphenol-rich plant food consumption reduced the risk of cognitive decline. However, the findings were tentative and by no means definitive. In the present study, we examined the impact of short-term oral administration of cinnamtannin A2 (A2), an (−)-epicatechin tetramer, on adult hippocampal neurogenesis and cognitive function in mice. Mice received supplementation with vehicle (20% glycerol) or 100 μg/kg A2 for 10 days. Then, we conducted the open field test, the object location test, and the novel object test. In the open field test, the A2-treated group tended to spend more time in the center of the arena, compared to the vehicle-treated group. The A2-treated group spent significantly more time exploring objects placed in different locations, compared to the vehicle-treated group. There were no significant differences between groups in the object preference index or in the novel object test. In addition, A2 administration significantly increased the number of hippocampal bromodeoxyuridine-labeled cells in the dentate gyrus, but not in the CA1 or CA3 regions. These results suggested that short-term administration of A2 may impact spatial memory by enhancing neurogenesis in the dentate gyrus of adult mice.

PurposeThe purpose of this paper is to investigate the distribution of in‐plane eddy currents in stator core packets of turbine generators, and to reveal the loss reduction effect by the slits in the stator teeth.Design/methodology/approachThe in‐plane eddy currents are calculated by a 3D finite element method that considers lamination of electrical steel sheets. First, this method is applied to a simple model that simulates the stator core of the turbine generators. The calculated losses are compared with the measured losses in order to confirm the validity. Next, the same method is applied to a 250 MVA class turbine generator.FindingsThe validity of the calculation method is confirmed by the measurement of the simple model. By applying this method to the turbine generator, it is clarified that the considerable in‐plane eddy currents are generated not only at the end stator packets, but also at the top of the teeth of the interior packets due to the duct space. It is also clarified that the in‐plane eddy‐current loss decreases as nearly half by the slits of the stator teeth.Originality/valueA reliable calculation method for the in‐plane eddy‐current loss in the turbine generators is developed. The results obtained by this method are valuable for the design of the generator from the viewpoint of heat conduction.

This paper describes analyses of in-plane eddy currents, which are generated by the perpendicular flux at both of end and interior stator core packets of turbine generators. The 3-D finite element method considering lamination of the electrical steel sheets is applied to the calculation. The validity of the analysis is examined by a simple apparatus that simulates the stator core of the turbine generator. It is clarified that the in-plane eddy currents are generated not only at the end stator packets, but also at the interior packet due to the duct space. It is also clarified that the in-plane eddy current loss decreases as nearly half by the slits of the stator teeth.