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Chemical looping combustion (CLC) of coal was conducted with 12 CuO-based oxygen carriers supported on SiO2, Al2O3, TiO2, and ZrO2 prepared by mechanical mixing. The influence of an inert support and the effect of particle size on the reactivity of CuO-based oxygen carrier particles were studied. Five mixed oxide oxygen carriers composed of different amounts of CuO and Fe2O3 on TiO2 were prepared to study the synergistic effect between two active metallic oxides. It was found that CuO-based oxygen carriers showed high reactivity in redox reactions. The onset temperature of the reduction reaction decreased when TiO2 was added as an inert support. The particles of CuXTi950 showed the highest reactivity to convert the coal. Although the smaller particle size of the oxygen carrier can enhance the coal conversion, it also makes it more difficult in the separation of the oxygen carrier from fly ash and unburned carbon. For mixed oxygen carriers, the synergistic effect between different active oxides was observed. From a reactivity and an energy-balance perspective, particles of CuO–Fe2O3/TiO2 mixed oxide oxygen carriers are suitable for use in CLC of coal. The X-ray diffractometer (XRD) and scanning electron microscope (SEM) were used for the characterization of the fresh and used oxygen carriers. Results support that direct CLC of coal is promising when CuO-based oxygen carriers are used at low temperatures.

The present study aimed to construct a novel recombinant adenovirus expression vector Ad-BMP2-IRES-HIF1αmu that expresses human bone morphogenetic protein (BMP2) and mutant hypoxia-inducible factor 1α, and investigated its effects in promoting neogenesis of bone and angiogenesis. The recombinant adenovirus BMP2, HIF1αmu and pIRES2-EGFP expression vectors were constructed and transfected into HEK293A cells. The groups were divided into group A, transfection with Ad-BMP2-IRES-HIF1αmu; group B, transfection with Ad-HIF1αmu-IRES-hrGFP-1; group C, transfection with Ad-BMP2-IRES-hrGFP-1; group D, transfection with Ad-IRES-hrGFP-1; group E, not transfected. Adenovirus liquid was transferred into rabbit mesenchymal stem cells (MSCs) pretreated with dexamethasone at the best multiplicity of infection (MOI). The mRNA and protein expression of BMP2 and HIF1α were detected by RT-PCR and western blot analysis. Adenovirus was successfully packaged. The expression level of HIF1α mRNA in group A and B was markedly higher than that in groups C, D and E, showing a significant difference (P<0.01). There was a significant difference in the expression level of BMP2 mRNA between group A and C (P<0.05) and this was markedly higher than that in groups B, D and E (P<0.01). The protein expression level of HIF1α in group A and B was markedly higher than that in groups C, D and E (P<0.01). The protein expression level of BMP2 in group A and C was markedly higher than that in groups B, D and E (P<0.01). The human BMP2-IRES-HIF1αmu adenovirus expression vector was successfully constructed and the experimental groups formed bone and blood vessels prior to the positive and negative control groups.

To investigate the functions of triple point-mutants of hypoxia-inducible factor 1α (HIF1α) in angiogenesis in bone defect regions under normoxic conditions. 1. Triple point-mutations (in amino acids 402, 564, and 803) in the HIF1α coding sequence (CDS) were induced by polymerase chain reaction. The triple mutant HIF1α (402/564/803) was inserted into the adenovirus pAdEasy-1 system for complete viral packaging and titer measurements. 2. For the in vitro experiment, rabbit bone marrow mesenchymal stem cells (MSCs) were divided into four experimental groups. The efficiency of infection was observed by the expression of human renilla reniformis green fluorescent protein (hrGFP). The HIF1α mRNA, protein and VEGF protein expression levels in infected cells in each experimental group were measured. 3. As in the in vivo experiment, the MSCs were divided into four groups and infected with the viral solutions from each complementary in vitro group and cultured under normoxic conditions. The MSCs were used as seed cells and transplanted into an apatite-wollastonite magnetic bioactive glass-ceramic (AW MGC) vector to construct artificial tissue-engineering scaffolds that were then implanted into the in vivo rabbit radial bone defect model. The animals from each group were killed 8 weeks after the surgery, and the tissues from the implantation region were harvested for the evaluation of the angiogenesis. 1. The 402,564, and 803 amino acids in CDS area were point mutated into alanine; three types of recombinant adenovirus were successfully constructed, packaged, and characterized. 2. The expression levels of HIF1α mRNA in A and B groups were significantly higher than those in the C and D groups (P < 0.05). The HIF1α and VEGF protein expression levels in A group were significantly higher than those in the other three groups (P < 0.05). 3. There was prominent angiogenesis in bone defect regions in group A animals. 1. Triple point-mutants of HIF1α efficiently expressed functional proteins under normoxic conditions. 2. Triple point-mutants HIF1α effectively promoted in vivo angiogenesis in bone defect regions.