Numerical calculations are carried out for natural convection induced by a temperature difference between a cold outer square enclosure and a hot inner circular cylinder. A two-dimensional solution for unsteady natural convection is obtained, using the immersed boundary method (IBM) to model an inner circular cylinder based on the finite volume method for different Rayleigh numbers varying over the range of 10 3-10 6. The study goes further to investigate the effect of the inner cylinder location on the heat transfer and fluid flow. The location of the inner circular cylinder is changed vertically along the center-line of square enclosure. The number, size and formation of the cell strongly depend on the Rayleigh number and the position of the inner circular cylinder. The changes in heat transfer quantities have also been presented.

The antihyperglycemic effect of a water extract (WE) and an alkali extract (AE) of the Fomitopsis pinicola fruit body was studied in streptozotocin (STZ)-induced diabetic rats. The STZ-induced diabetes mellitus (DM) control group lost a significant amount of body weight, whereas the normal control group (NC) gained weight; however, the DM-AE group gained a significant amount of weight, with weight gain approaching normal. Feed intake by the DM-AE group was also similar to the NC group. The liver and kidney weights per body weight increased with the STZ treatment; however, the weights were lower in the F. pinicola-treated groups and nearly normalized in the DM-AE group. The weights of the heart, lungs, and spleen were not influenced by the STZ treatment. Blood glucose levels of F. pinicola-treated DM groups were significantly lower than that of the DM group. In particular, STZ-induced hyperglycemia was remarkably inhibited by the AE-supplemented diet. Serum insulin levels were decreased with STZ injection; however, the decreased levels were almost restored to the NC level with F. pinicola supplementation. The increased serum fructosamine levels associated with hyperglycemia were decreased with the F. pinicola treatment. Cells of the pericentral regions were found to have significant swelling, and some necrotic cells were observed in the pancreas of DM animals; however, pancreatic tissue damage by STZ in the F. pinicola-supplemented diet groups was ameliorated. In this study, the AE from F. pinicola showed the highest antidiabetic effect among the treatments. These results indicate that constituents of F. pinicola may regulate hyperglycemia via either increased insulin secretion during recovery or the prevention of STZ-induced pancreatic damage. This is the first report of antihyperglycemic effects of F. pinicola in STZ-induced DM rats.

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