Parallel pore and surface diffusion of levulinic acid in basic polymeric adsorbents.

The equilibrium and kinetics of levulinic acid (LA) adsorption on two basic polymeric adsorbents, 335 (highly porous gel) and D315 (macroreticular), were investigated. Experimental adsorption rates in batch stirred vessels under a variety of operating conditions were described successfully by the parallel pore and surface diffusion model taking into account external mass transfer and nonlinear Toth isotherm. The film-pore diffusion model was matched with the rate data and the resulting apparent pore diffusivities were strongly concentration-dependent and approached to a constant value for 335 adsorbent. Thus, the constant value was taken as the accurate pore diffusivity, while the pore diffusivity in D315 was estimated from the particle porosity. The surface diffusivities decreased with increasing initial bulk concentration for both adsorbents. The inverse concentration dependence was correlated reasonably well to the change of isosteric heat of adsorption as amount adsorbed.

[Miniaturized metacarpus steel plate for treatment of epiphysis injury].

OBJECTIVE: To observe the clinical effects of miniaturized metacarpus steel plate for the treatment of child epiphysis injury, and to analyse its clinical advantages in the child epiphysis injury. METHODS: From June 2004 to May 2009, 85 children with epiphysis injury treated with miniaturized metacarpus steel plate included 52 boys and 33 girls with an average age of 6.6 years old ranging from 1 to 14 years. All the children suffered from just one part injury. There were 68 cases of upper limb injury, 19 of which were humerus epicondyle injury, 16 humerus head injury, 12 olecranon injury, 14 distal radius injury and 7 head of radius injury. The other 17 cases were lower limb injury, 12 of which were femur epicondyle injury and 5 tibia epicondyle injury. RESULTS: All children obtained good intention,and no postoperative complications occurrenced. Eighty-one children were followed up for 6 months to 5 years (averaged 2.6 years). The results were evaluated at 4 weeks after the operation and showed that there were excellent in 44 cases, good in 21 cases, fair in 11 cases and poor in 9 cases. CONCLUSION: Treatment of child epiphysis injury with miniaturized metacarpus steel plate can achieve perfect anatomical reduction in the early stage, protect the biological environment of the recovery. This treatment makes the postoperative joint functions and movements recovery nice, barely cause any bone malformation, and worth further clinical applications.