Background: In order to keep up the optimal iron status in chronic hemodialysis patients, it is important to know how much iron is lost due to hemodialysis. Residual blood associated with the hemodialysis procedure together with blood sampling inevitably causes the loss of iron in chronic hemodialysis patients. Recent advances in hemodialysis techniques might have reduced this complication. In this cross-sectional study, we directly measured total iron loss by hemodialysis. Methods: Two hundred thirty-nine patients who received chronic hemodialysis at Otowa Memorial Hospital were enrolled; 65.7% of patients were men, and mean age was 67 ± 6.4 years (mean ± SD) and 43.2% were diabetic. Residual blood in blood tubing set and dialyzer after rinse back with saline was collected and homogenized. The iron content including free, protein-bound and heme iron was measured using an atomic absorption spectrometry. Results: The mean iron content in residual blood was 1,247.3 ± 796.2 µg (mean ± SD) and the median was 1,002 µg (95% CI 377.6-3,461.6 µg), indicating 160.8 mg (95% CI 58.9-540.0 mg) iron loss annually when hemodialysis was performed 156 times a year. Fifty milliliter whole blood for monthly blood test and another 2 ml of whole blood lost by paracentesis at every dialysis session contains 228.6 and 118.9 mg iron at 11 g/dl hemoglobin, respectively. Therefore, an annual total iron loss due to hemodialysis comes to 508.3 mg (95% CI 406.4-887.5 mg). Conclusions: Five hundred milligram of annual iron supplementation might be sufficient to maintain iron status in hemodialysis patients, which is less than the dose recommended as 1,000-2,000 mg a year. Further study will be required to verify this iron supplementation dosage with recent hemodialysis procedure.

By carrying out the hydraulic experiments in a one-dimensional open channel and two-dimensional basin, we clarified the process of how a landslide on a uniform slope causes the generation of a tsunami. The effect of the interactive force that occurs between the debris flow layer and the tsunami is significant in the generation of a tsunami. The continuous flow of the debris into the water makes the wave period of the tsunami short. The present experiments apply numerical simulation using the two-layer model with shear stress models on the bottom and interface, and the results are compared. The simulated debris flow shows good agreement with the measured results and ensures the rushing process into the water. We propose that the model use a Manning coefficient of 0.01 for the smooth slope and 0.015 for the rough slope, and a horizontal viscosity of 0.01 m 2 /s for the landslide; an interactive force of 0.2 for each layer is recommended. The dispersion effect should be included in the numerical model for the propagation from the shore.

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