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Poly(L-lactic acid) (PLLA) tissue engineering scaffolds with porous inner structures of individual fibers and controllable architectures were successfully fabricated from the homogeneous polymer-solvent-nonsolvent system (PLLA, CH(2)Cl(2) and DMF) by a single capillary electrospinning with certain conductive patterned templates as fiber collectors. PLLA was dissolved in dimethylformamide (DMF) and methylene chloride (CH(2)Cl(2)) mixed solvent with different ratios. Semi-hollow fiber with porous inner structure and compact shell wall was formed by controlling the content of DMF in the mixed solvents. It is believed that the phase separation should be the key origin for the formation of this microstructure. In order to mimic the natural extracellular matrix (ECM) with a specific structure, conductive patterned collectors were designed and employed to manufacture PLLA ultrafine fibrous scaffolds with three-dimensional architectures. We believe these kinds of multi-scale biodegradable fibrous scaffolds with specific microstructure and macro-architectures could make the electrospun fibrous scaffold better mimic the natural extracellular matrix to satisfy tissue engineering.

Chemical-looping with oxygen uncoupling (CLOU) is an innovative method to oxidize fuels with inherent CO2 sequestration, which utilizes a solid oxygen-carrier material to provide O2 for fuel combustion. In this study, a range of CuO-based oxygen-carrier particles have been manufactured and examined. Out of 24 samples prepared, 10 were examined in a batch fluidized-bed reactor, of which three were selected for further examination by continuous operation in a small circulating fluidized-bed reactor system. Composite particles consisting of CuO as active phase and support material such as ZrO2, YSZ, CeO2, and MgAl2O4 were capable of providing full conversion of CH4 at 900 and 925 °C, and were also found to release gas phase O2 into inert atmosphere when fluidized with N2. Particles using semiactive support such as Fe2O3, Mn2O3, and Al2O3 formed combined spinel phases with CuO. Such materials were still capable of releasing gas phase O2 but at different concentrations as compared to particles with inert support. Materials with semiactive support had less good reactivity with CH4. No formation of unexpected phases could be detected by X-ray diffractometry, and all chemical reactions were completely reversible. The three materials that were examined in continuous operation were readily capable of providing more or less full conversion of natural gas under the chosen conditions. However, they also suffered from quick attrition and turned into a flour-like substance after a few hours of continuous operation with fuel. Crushing strength analysis showed that particles used in continuous operation were physically much weaker than fresh. In total, 23 h of continuous operation with fuel addition was recorded.

Perovskite structure oxygen carriers with the general formula CaMn x Mg 1-x O 3-were spray-dried and examined in a batch fluidized bed reactor. The CLOU behavior, reactivity towards methane, and syngas were investigated at temperature 900 ∘ C to 1050 ∘ C. All particles showed CLOU behavior at these temperatures. For experiments with methane, a bed mass corresponding to 57 kg/MW was used in the reactor, and the average CH 4 to CO 2 conversion was above 97% for most materials. Full syngas conversion was achieved for all materials utilizing a bed mass corresponding to 178 kg/MW. SEM/EDX and XRD confirmed the presence of MgO in the fresh and used samples, indicating that the Mg cation is not incorporated into the perovskite structure and the active compound is likely pure CaMnO 3-. The very high reactivity with fuel gases, comparable to that of baseline oxygen carriers of NiO, makes these perovskite particles highly interesting for commercial CLC application. Contrary to NiO, oxygen carriers based on CaMnO 3-have no thermodynamic limitations for methane oxidation to CO 2 and H 2 O, not to mention that the materials are environmentally friendly and can utilize much cheaper raw materials for production. The physical properties, crystalline phases, and morphology information were also determined in this work.