Experimental Study of the Influence of Moisture Content on the Pore Structure and Permeability of Anthracite Treated by Liquid Nitrogen Freeze-Thaw.

The liquid nitrogen freeze-thaw (LN2-FT) method has been widely used to improve the coal permeability in the coalbed methane (CBM) production. However, the influence of moisture content on the permeability of coal treated by LN2-FT remains unclear, limiting the broad application of this technique. A novel seepage system was proposed to analyze the permeability evolution of anthracite coal samples treated by LN2-FT. Moreover, variations of the pore structure were analyzed using scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), and low-field NMR. The results showed that pores and fractures appeared on the coal surface after the LN2-FT treatment. As the moisture content of the coal increased, more pores and fractures tended to be formed during the LN2-FT treatment. The total pore volume, porosity, and average pore diameter of the anthracite coal after the treatment were 1.77, 2.44, and 5.58 times higher, respectively, than that of the raw coal. The change in the specific surface area exhibited three trends as the moisture content of the coal samples increased: a slow descent, a steady increase, and a rapid descent. Moreover, it was found that the LN2-FT treatment increased the connections between pores and fractures, improving gas migration in the coal. Furthermore, the LN2-FT treatment significantly increased the permeability of the anthracite coal samples. The higher the coal moisture, the higher the permeability of the coal samples after the LN2-FT treatment. Hence, the LN2-FT technique can substantially improve the permeability of coal reservoirs, providing essential information for the efficient utilization of CBM.

[Study on the recombinant adeno-associated virus vector carrying LacZ gene expression in the skeletal muscle].

OBJECTIVE: To look for a gene delivery route to the treatment of Duchenne muscular dystrophy(DMD). METHODS: The recombinant adeno-associated virus vector(rAAV) carrying a LacZ reporter gene was constructed. rAAVLacZ was delivered into the skeletal muscle tissue of C57/BL6 mice by intramuscular injection. Then an intraarterial delivery route was taken to reveal whether rAAVLacZ could transduce muscle tissue. RESULTS: (1) The LacZ gene was efficiently transduced and expressed persisting for 5 months after intramuscular injection. (2) The membrane of muscle and smooth muscle of vessel was widely transduced by intra-arterial delivery rAAVLacZ. CONCLUSION: These data provide the evidence that rAAVLacZ can efficiently transduce muscle for a long period. Improving intraarterial gene delivery will be promising means for rAAV-mediated gene therapy for generalized skeletal muscle of DMD.