Double-layer model predictive control integrated with zone control.

This paper proposed a double-layer model predictive control (DLMPC) strategy integrated with zone control. In the steady-state target calculation (SSTC) layer, the controlled output variables are pretreated based on the analysis of process principle and production data. Subsequently, the optimal input-output targets and corresponding zone parameters are obtained by solving the steady-state optimization problem and transmitted to the dynamic control layer for tracking. Meanwhile, the weighted and priority soft constraints relaxation methods are discussed when the SSTC problem is infeasible. Compared with conventional DLMPC and zone model predictive control (ZMPC), the proposed algorithm can not only achieve smooth control, but also have better robustness and economic performance. Finally, a simulation example is taken to show the effectiveness of the proposed method.

A novel therapy strategy for bile duct repair using tissue engineering technique: PCL/PLGA bilayered scaffold with hMSCs.

The current clinical treatments for complications caused by hepatobiliary surgery still have some inevitable weakness. The aim of the study was to fabricate a tissue-engineered bile duct that utilized a novel bilayered polymer scaffold combined with human bone marrow-derived mesenchymal stem cells (hMSCs) for new treatment of biliary disease. The biocompatibility of polycaprolactone (PCL) (PCL)/poly(lactide-co-glycolide) (PLGA) scaffold with hMSCs was first examined, and the hMSC-PCL/PLGA constructs (MPPCs) prepared. The MPPCs and blank scaffolds were then transplanted into 18 pigs for evaluation its efficacy on bile duct repairing, respectively. In vitro, the PCL/PLGA scaffold was verified to support the adhesion, proliferation and matrix deposition of hMSCs. There was no sign of bile duct narrowing and cholestasis in all experimental animals. At 6 months, the MPPCs had a superior repairing effect on the bile duct injury, compared with the blank PCL/PLGA scaffolds. Therefore, the implanted scaffolds could not only support the biliary tract and allow free bile flow but also had direct or indirect positive effects on repair of injured bile duct. Copyright © 2015 John Wiley & Sons, Ltd.

Preparation of polycaprolactone microspheres-aggregated scaffold with ultra big pores and fuzzy sphere surface by a one-step phase separation method.

A microspheres-aggregated scaffold with ultra big pores (over 300 µm) and fuzzy microspheres is fabricated by incubating polycaprolactone (PCL)/tetrahydrofuran (THF) solution in a -20°C refrigerator, following by freeze-drying. Formation of the scaffold is mainly governed by the crystallization of the PCL polymer at appropriate conditions. All the 10-20% PCL/THF solutions yield the microspheres-aggregated scaffolds when the initial solution temperature is higher than 37°C, whereas the 10-15% solutions form dense membranes when the initial solution temperature is below 25°C. The size of the microspheres and pores is as large as 70-150 µm and 170-816 µm, respectively. The PCL microspheres-aggregated scaffold can better support the adhesion and proliferation of bone marrow mesenchymal stem cells (BMSCs) compared to the traditional porous scaffold obtained by a porogen leaching method. The tendencies of chondrogenesis and osteogenesis differentiation of BMSCs are observed on the microspheres-aggregated scaffold and the ordinary porous scaffold, respectively.