Conservation of the weathered historic calcareous stones by apatite was studied. By mimicking the growth of bone, calcium and phosphorus were introduced into the weathered stone and then mineralized at room temperature. The conservation efficiency was investigated by SEM, EDX, XRD, ''Scotch Tape Test'' (STT), compressive strength test, capillary water uptake test, water vapor permeability test and weather resistance test. The results of SEM, EDX and XRD showed that the produced bone-like hydroxyapatite could bind the introduced calcium carbonate and the weathered stone blocks together. The test results also indicated that this conservation method could improve the surface strength, compressive strength and weather resistance of the treated samples significantly. Besides, due to the porous nature of the bone-like apatite, the water vapor permeability of the treated stone was not affected and its ''breathe function'' was retained. Therefore, the proposed method will be a good candidate for the in situ conservation of historic calcareous stones.
Experimental
MaterialsCalcium chloride (CaCl 2 ), sodium hydroxide (NaOH), Vaseline, 2-propanol and ammonium phosphate ((NH 4 ) 3 PO 4 ),
Embryonic stem (ES) cells are of significant interest either as an in vitro model recapitulating early embryonic development or as a renewable source of therapeutically useful cells. ES cells aggregation is important for embryoid bodies (EBs) formation and the subsequent generation of ES cell derivatives. This study was conducted to describe scalable production of EBs by the rotary cell culture system (RCCS, STLV type) and estimate the feasibility of constructing engineered cardiac tissue (ECT). In comparison with suspension culture in a Petri dish, the efficiency of the dynamic process was analyzed with respect to the yield of EB formation and their cardiomyocyte differentiation. Cardiomyocyte differentiation was evaluated by immunohistochemical analysis. After the elementary enrichment by gradient percoll, ES cell-derived cardiomyocytes were applied to construct ECT. Cell gross morphology, spatial distribution, and ultrastructure were evaluated by using histological analysis, confocal laser scanning microscopy, and transmission electron microscopy. Results showed that EB efficiencies in STLV were nearly 1.5-2.0 times higher than that of liquid suspension cultures, and cardiomyocyte differentiation of EBs progressed in a normal course after the dynamic cultivation in STLV. Additionally, the differentiated cultures could be enriched elementarily by gradient percoll. Once cast into the collagen strand, cells grew well and became more matured in Petri dishes. Synchronous contraction of the cell cluster was observed on the surface of the ECT, and cell connection was also established. It was the first report to have beating ES-derived cardiomyocytes on a 3-D collagen scaffold, which might provide a promising model for physiological and pharmacological studies and tissue replacement therapy.
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