background: the well documented source for adult multipotent stem cells is spermatogonial stem cells (sscs). they are the foundation of spermatogenesis in the testis throughout adult life by balancing self-renewal and differentiation. the aim of this study was to assess the effect of percoll density gradient and differential plating on enrichment of undifferentiated type a spermatogonia in diss...

a small salt gradient solar pond with an average surface area of 1.8 m2 and depth of 0.8m has been tested. the depths of storage, gradient and surface zones are 0.3, 0.27 and 0.07m, respectively. the temperature of the storage zone for the summer days reaches its maximum of 65˚ c after about 8 days. daily variation of the storage zone temperature was about 8˚c which is due to small volume of th...

Functionally graded materials (FGM) in the form of layered structure consisting of yttria stabilized zirconia (8 mol% Y2O3) and nickel were fabricated by spark plasma sintering procedure. The relative density, linear shrinkage and Vickers hardness of each layer of graded materials were measured. The microstructure and the composition of these components were studied. The results obtained show t...

For optimal hydrocarbon recovery from fractured reservoirs, a critical issue is to gain an accurate understanding of the natural fracture system. Currently, fracture characterization using amplitude based technologies is routinely performed relying on amplitude versus angle/offset (AVA/AVO) and azimuth (AVAZ) to exploit anisotropic gradient behavior, which is today commonly used in the industry...