RESUMEN
A series of model tests were conducted to investigate the bearing capacity and reinforced mechanism of a horizontal-vertical (H-V) geogrid-reinforced foundation. The bearing capacities of the unreinforced foundation, the conventional geogrid, and the H-V geogrid-reinforced foundation were compared. The parameters, including the length of the H-V geogrid, the vertical geogrid height, the depth of the top layer, and the number of H-V geogrid layers, are discussed. Through experiments, it was found that the optimal length of H-V geogrid is around 4B, the optimal vertical geogrid height is approximately 0.6B, and the optimal depth of the top H-V geogrid layer is between 0.33B and 1B. The optimal number of H-V geogrid layers is 2. The result also indicates that the bearing capacity of H-V geogrid is almost 1.7 times greater than that of conventional geogrid. Additionally, the maximum top subsidence of H-V geogrid-reinforced foundation decreased by 13.63% compared to that of conventional geogrid-reinforced foundation. Under the same settlement, the bearing capacity ratio of two H-V geogrid-reinforced foundation layers is 75.28% higher than that of one layer. The results also demonstrate that the vertical elements of H-V geogrid interlock the sand from being displaced under the applied load and redistribute the surcharge over a wider area, thereby increasing the shear strength and improving the bearing capacity of an H-V geogrid-reinforced foundation.
RESUMEN
Our previous studies showed that pretreatment with corticosteroids, which inhibits release of arachidonic acid (precursor of prostaglandins and leukotrienes), partially prevented salicylate-induced hearing loss in vivo. The purpose of this study was to determine the effect of pretreatment with corticosteroid (dexamethasone sodium phosphate) on isolated cochlear outer hair cells (OHCs) exposed to salicylate in vitro. Isolated OHCs from the chinchilla cochlea were exposed to salicylate with or without pretreatment with dexamethasone. Images were stored and analyzed on the Image program. The OHCs exposed to salicylate demonstrated a significant shortening in cell length. The OHCs exposed to salicylate after pretreatment with dexamethasone exhibited no significant change in cell length. We conclude that corticosteroid treatment of isolated OHCs is effective in blocking the morphological changes induced by salicylate. This study gives additional evidence that salicylate ototoxicity is mediated by alteration in the levels of arachidonic acid metabolites.