Supercritical phase inversion of starch-poly(e-caprolactone) for tissue engineering applications

In this work, a starch-based polymer, namely a blend of starch-poly(ε-caprolactone) was processed by supercritical assisted phase inversion process. This processing technique has been proposed for the development of 3D structures with potential applications in tissue engineering applications, as scaffolds. The use of carbon dioxide as non-solvent in the phase inversion process leads to the formation of a porous and interconnected structure, dry and free of any residual solvent. Different processing conditions such as pressure (from 80 up to 150 bar) and temperature (45 and 55°C) were studied and the effect on the morphological features of the scaffolds was evaluated by scanning electron microscopy and micro-computed tomography. The mechanical properties of the SPCL scaffolds prepared were also studied. Additionally, in this work, the in vitro biological performance of the scaffolds was studied. Cell adhesion and morphology, viability and proliferation was assessed and the results suggest that the materials prepared are allow cell attachment and promote cell proliferation having thus potential to be used in some for biomedical applications.Ana Rita C. Duarte is grateful for financial support from Fundacao para a Ciencia e Tecnologia through the grant SFRH/BPD/34994/2007

Modeling Water Saturation Points in Natural Gas Streams Containing CO₂and H₂S-Comparisons with Different Equations of State

Since the discovery of the Pre-Salt layer in Brazilian waters, production of high gas–oil ratio (GOR) has increased considerably. This gas has a high content of water, CO₂, and sometimes H₂S. A study in different conditions was conducted using several equations of state (EoS) such as Peng–Robinson, GERG-modified Peng–Robinson (PR-ISO-04), Soave–Redlich–Kwong, and Cubic Plus Association (CPA). Petrobras’ Process Simulator has been used to perform the phase equilibrium calculations. All the EoS except for CPA used parameters from the literature. A new parameter estimation procedure for CPA has been proposed using a particle swarm optimization algorithm followed by the SIMPLEX method presenting themselves together as an optimal approach. The results show that PR-ISO-04 can be considered to be an improvement compared to the original Peng–Robinson but CPA appears to be the most promising approach to be used for predicting dew points for water-containing mixtures, especially at high pressures