3D Printing of Well Dispersed Electrospun PLGA Fiber Toughened Calcium Phosphate Scaffolds for Osteoanagenesis

Although the toughening of Calcium phosphate(CaP)scaffold by the addition of fiber has been well recognized,integrated mechanical,structural and functional considerations have been neglected in the design and fabrication of CaP scaffold implant.The emerging 3D printing provides a promising technique to construct CaP scaffold with precise size and elaborate microstructure.However,the most challenge is to extrude smoothly the CaP paste containing fibers for frequently-used extrusion-based 3D printing.In this study,frozen section and chemical dispersant(Pluronic F127,F127)were employed jointly to prepare non-aggregated polylactic-co-glycolic acid(PLGA)fibers.The injectability of CaP pastes with well dispersed PLGA fibers was more than 90%when the content of PLGA fibers was no more than 3 wt%.Meanwhile rheological property of CAP pastes with well dispersed fibers showed shear thinning,which were both beneficial to extrude CaP paste with well dispersed fibers for 3D printing.Moreover,these CaP scaffolds showed ductile fracture behavior due to the pullout and bridging effect of PLGA fibers.The cell proliferation and alkaline phosphatase(ALP)activity indicated that 3D printed CAP scaffold containing PLGA fibers possesses excellent biocompatibility and facilitate osteogenic differentiation ability.Thus,it was feasible to print CaP pastes with well dispersed PLGA fibers to construct toughening CaP scaffolds with the higher shape fidelity and complex structures,which had significant clinical potentials in osteoanagenesis due to their higher toughness and excellent biocompatibility.

Enhancement and mapping of tolerance to salt stress and 5-fluorocytosine in synthetic yeast strains via SCRaMbLE

Varied environmental stress can affect cell growth and activity of the cellular catalyst.Traditional path of adaptive evolution generally takes a long time to achieve a tolerance phenotype,meanwhile,it is a challenge to dissect the underlying genetic mechanism.Here,using SCRaMbLE,a genome scale tool to generate random structural variations,a total of 222 evolved yeast strains with enhanced environmental tolerances were obtained in haploid or diploid yeasts containing six synthetic chromosomes.Whole genome sequencing of the evolved strains revealed that these strains generated different structural variants.Notably,by phenotypic-genotypic analysis of the SCRaMbLEd strains,we find that a deletion of gene YFR009W(GCN20)can improve salt tolerance of Saccharomyces cerevisiae,and a deletion of gene YER056C can improve 5-flucytosine tolerance of Saccharomyces cerevisiae.This study shows applications of SCRaMbLE to accelerate phenotypic evolution for varied environmental stress and to explore relationships between structural variations and evolved phenotypes.

Research and application of the virtual simulation system teaching method in copper pyrometallurgy

Copper pyrometallurgy has been holding a special place in the copper smelting industry.However,it is hard to explore the effect of parameters on production effectively due to the inoperable practice in the factory.The physical and chemical changes during the metallurgical process of copper smelting are also too complex to be observed.Therefore,we designed and built a virtual factory for copper pyrometallurgy,copper pyrometallurgy virtual simulation system(CPVSS),to simulate the copper smelting plant.The entire technical routes,system function,the main productive principle,technological process,and conditional tests were fully simulated in the CPVSS.It also provided a solution for the observation of internal phenomena in this paper.Moreover,sample computations were provided in this paper to illustrate the parameter simulation of the smelting process.A novel interactive experimental model was also constructed with virtual simulation technology and network multimedia technology,which provides powerful support for copper pyrometallurgy learning.