Transverse alignment of fibers in a periodically sheared suspension: an absorbing phase transition with a slowly varying control parameter

Shearing solutions of fibers or polymers tends to align fiber or polymers in the flow direction. Here, non-Brownian rods subjected to oscillatory shear align perpendicular to the flow while the system undergoes a nonequilibrium absorbing phase transition. The slow alignment of the fibers can drive the system through the critical point and thus promote the transition to an absorbing state. This picture is confirmed by a universal scaling relation that collapses the data with critical exponents that are consistent with conserved directed percolation.     

Preparation,characterization and in vitro assessment of ibuprofen loaded calcium phosphate/gypsum bone cements

In the present study, pure and mixed calcium phosphate/gypsum cements were prepared and characterized. Chara‐cterizations were performed using X‐ray diffraction FTIR spectroscopy, thermogravimetric analysis, and Scanning Electron Microscopy. Furthermore, the mechanical proper‐ties of the materials were studied and it was found that they depend with the gypsum content. Bioactivity tests after incubation in 2xSBF solution revealed dense apatite structure on the samples containing α‐tricalcium phosphate while the pure gypsum specimens showed sparse distributed tiny apatite crystals. Finally, 1% and 2% wt of the anti‐inflammatory drug ibuprofen incorporated into the cement paste and the release behaviour of the drug was stu‐died for 18 days in PBS solution. The results showed marked differences in the release profiles of ibuprofen for the different formulations. Complete release of the drug was noticed in the case of pure calcium phosphate cements within 18 days whereas ca. 35–40% of the drug was released from its congeners containing gypsum at the same timescale.