Reconstruction of proliferative activity of hair follicle cells based on the geometric parameters of the hair shaft
Proliferative activity and differentiation rate of hair follicle cells determine the shape of the hair and parameters of hair growth. The hair growth rate and changes of geometric parameters of the hair shaft during its elongation (in time) are analyzed to reconstruct the proliferation dynamics of follicle matrix cells. The reconstruction demonstrated that the number of cells of hair follicle matrix increases in a typical manner, including the phase of exponential growth and the stationary phase.
An analysis of the growth of the retinal cell population in embryonic chicks yielding proliferative ratios, numbers of proliferative and non‐proliferative cells and cell‐cycle times for successive generations of cell cycles
Growth curves of the retinal cell population of embryonic chicks were fitted by a branching‐process model of cell population growth, thereby estimating the proliferative ratios and mean cell‐cycle times of the generations of cell cycles that underlie retinal growth. The proliferative ratio determines the proportion of cells that divides in the next generation, so the numbers of proliferative and non‐proliferative cells in each generation of cell cycles were obtained. The mean cell‐cycle times determine the times over which the generations are extant. Assuming growth starts from one cell in generation 0, the proliferative cells reach 3.6 × 106 and the non‐proliferative cells reach 1.1 × 106 by generation 23. The next four generations increase the proliferative cell numbers to 13.9 × 106 and produce 20.1 × 106 non‐proliferative cells. In the next five generations in the end phase of growth, non‐proliferative cells are produced in large numbers at an average of 13.9 × 106 cells per generation as the retinal lineages are completed. The retinal cell population reaches a maximum estimated here at 98.2 × 106 cells. The mean cell‐cycle time estimates range between 6.8 and 10.1 h in generations before the end phase of growth and between 10.6 and 17.2 h in generations in the end phase. The retinal cell population growth is limited by the depletion of the proliferative cell population that the production of non‐proliferative cells entails. The proliferative ratios and the cell‐cycle‐time distribution parameters are the likely determinants of retinal growth rates. The results are discussed in relation to other results of spatial and temporal patterns of the cessation of cell cycling in the embryonic chick retina.
Heat Transfer Characteristic for a New Plate Metal Hydride Reactor
The property of major metal hydride reactors in the world was analyzed and a new plate metal hydride reactor was designed.An experimental facility to test the metal hydride reactor was also designed correspondingly.The effective thermal conductivity of the plate metal hydride reactor was measured by varying the initial metal hydride packing fraction,the kind of filled gas and the pressure of the filled gas,cycle numbers.The test results show that the effective thermal conductivity of the reactor,has exceeded(7.5) W/(m·K) before activation,which is increased greatly.After alloy activation,the effective thermal conductivity of the reactor has a linear change trend with the hydrogen pressure during the interval 0.1~3.5 MPa.The effective thermal conductivity of the reactor just only decreases quickly at the beginning,but becomes stable after several cycles.