Initiator-free injectable hydrogels are very interesting for drug and/or cell delivery applications, since they can be administered in a minimally invasive way, and avoid the use of potentially harmful chemical initiators. In the current work, oxidized dextran crosslinked with adipic acid dihydrazide hydrogels were further characterized and tuned to produce formulations, with the aim of producing an injectable formulation for the possible treatment of posterior eye diseases. The gelation rate and the hydrogel dissolution profile were shown to be dependent on the balance between the degree of dextran oxidation, and the concentration of both components. For the in vitro studies, rabbit corneal endothelial cells were seeded on the hydrogels to assess cytotoxicity. Hydrogels prepared with low oxidized dextrans were able to promote cell adhesion and proliferation to confluence in just 24h, while more highly oxidized samples promoted cell adhesion and proliferation, but without achieving confluence. Cell viability studies were performed using MTS assays to verify the non-cytotoxicity of hydrogels and their degradation byproducts, rendering these formulations attractive for further in vivo studies.

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Pulp fiber suspensions are complex systems because the components present singular and complex interactions between them. A mechanistic model for the turbulent flow regime of industrial pulp suspensions was developed on the basis of a CFD code, using the chemical engineering module of COMSOL Multiphysics software. The standard k-ε turbulence model, chosen to simulate turbulence, was tested and validated using four different industrial pulp suspensions previously characterized experimentally. The modeled pressure drop profiles agree very well with the experimental results obtained in a pilot rig. Therefore, the k-ε turbulence model for the simulation of pulp fiber suspension flows, associated with experimental rheological data, proved to be a prompt strategy to attain good prediction of pressure drop for fiber suspension flows. Moreover, the adjustment of the turbulence parameters confirmed previous studies, where it was concluded that the existence of particles, such as fibers, in a fluid flow induces a turbulence damping.

The transport between different equipment and unit operations plays an important role in pulp and paper mills because fiber suspensions differ from all other solid-liquid systems, due to the complex interactions between the different pulp and paper components. Poor understanding of the suspensions’ flow dynamics means the industrial equipment design is usually conservative and frequently oversized, thus contributing to excessive energy consumption in the plants. Our study aim was to obtain additional knowledge about the dynamic behavior of industrial pulp suspensions in order to evaluate the relative importance of the factors that influence pressure drop. To obtain mathematical correlations to quantify pressure drop for the transport of pulp suspensions, we studied four different industrial pulp suspensions (recycled pulp, eucalypt bleached kraft pulp, pine unbleached kraft pulp, and eucalypt [90%] + pine [10%] bleached kraft pulp) in a pilot rig specially designed and built for the effect.