Transference Kinetics of Radionuclide ⁹⁵Nb in the Aquatic Ecosystem

The dynamics of transportation, accumulation, diminishment and distribution of 95Nb in a simulated aquatic ecosystem was studied using the isotope-tracer technique, and a fitting equation was established by application of a closed, five-compartment model. The results showed that when 95Nb was introduced into an aquatic system, it was transported and transformed via deposition in combination with other ions, and adsorption and absorption by aquatic organisms, resulting in redistribution and accumulation in different parts of the organisms. Following addition, the spe- cific activity of 95Nb in water decreased sharply within a short time, and then after reaching a certain value, it decreased more slowly. Sediment accumulated large amounts of 95Nb through the exchange of ions. Hyacinth (Eichhornia crassipes) also adsorbed a large amount of 95Nb in a short period of time. Snails (Bellamya purificata) and fish (Carassius auratus) were found to have a poor adsorption capacity of 95Nb. The amount of 95Nb found in the snail flesh was greater than that in the shell, and the 95Nb found in the fish was mainly distributed in the viscera. The amount of 95Nb in each individual component of the experimental system was affected over time.

Rhodium catalyzed regioselective arene homologation of aryl urea via double C–H bond activation and migratory insertion of alkyne

A convenient rhodium catalyzed oxidative arene homologation of aniline derivatives with symmetrical or unsymmetrical alkynes using Cu（OAc）2 as oxidant is described. Urea group is shown to be effective as a directing group for initial ortho C–H activation. Two migratory insertion events of alkyne into Rh–C bond occur successively, both with complete regioselectivity. This method is particularly useful for synthesis of polyarenes with different substituents, which has not been reported with conventional protocol. A mechanism has been proposed to explain the observed data.

3D bioprinting of conductive hydrogel for enhanced myogenic differentiation

Recently,hydrogels have gained enormous interest in three-dimensional(3D)bioprinting toward developing functional substitutes for tissue remolding.However,it is highly challenging to transmit electrical signals to cells due to the limited electrical conductivity of the bioprinted hydrogels.Herein,we demonstrate the 3D bioprinting-assisted fabrication of a conductive hydrogel scaffold based on poly-3,4-ethylene dioxythiophene(PEDOT)nanoparticles(NPs)deposited in gelatin methacryloyl(GelMA)for enhanced myogenic differentiation of mouse myoblasts(C2C12 cells).Initially,PEDOT NPs are dispersed in the hydrogel uniformly to enhance the conductive property of the hydrogel scaffold.Notably,the incorporated PEDOT NPs showed minimal influence on the printing ability of GelMA.Then,C2C12 cells are successfully encapsulated within GelMA/PEDOT conductive hydrogels using 3D extrusion bioprinting.Furthermore,the proliferation,migration and differentiation efficacies of C2C12 cells in the highly conductive GelMA/PEDOT composite scaffolds are demonstrated using various in vitro investigations of live/dead staining,F-actin staining,desmin and myogenin immunofluorescence staining.Finally,the effects of electrical signals on the stimulation of the scaffolds are investigated toward the myogenic differentiation of C2C12 cells and the formation of myotubes in vitro.Collectively,our findings demonstrate that the fabrication of the conductive hydrogels provides a feasible approach for the encapsulation of cells and the regeneration of the muscle tissue.