RESUMO
Molecular dynamic simulation of a high explosive, RDX, mixed with AlH3 nanoparticles was performed by a newly parameterized ReaxFF force field. Testing of the ReaxFF shows that the mean absolute errors of the densities and bond lengths between calculated and experimental values are less than 7% and 3%, respectively. Using the ReaxFF, effects of AlH3 nanoparticles with different radii on the thermal decomposition of RDX were revealed. A new mechanism of the generation and the consumption of H2 was discovered in the explosion. The H2 is released by AlH3 firstly and then it reacts with NO2 and CO2 from the decomposition of RDX, leading to an increase of H2O, NO and CO. Meanwhile, the size effect of AlH3 upon the reaction was also revealed. As a result, the number of produced H2O and CO2 molecules increases by 10.38% and 56.85%, respectively, when the radius of AlH3 nanoparticles decreases from 1.10 to 0.68 nm. This showed that RDX decomposes more completely with smaller AlH3 nanoparticles, which was further demonstrated by the analysis of reaction residues and diffusion coefficients.
RESUMO
OBJECTIVE: To investigate the effects of T lymphoma invasion and metastasis inducing factor 1 antisense oligodeoxynucleotides (Tiam 1 ASODN) transfection on the morphology and invasive migration potential of gastric cancer cells. METHODS: The higher invasive and migratory subgroup (M(H)) were separated from human gastric cancer cell line MKN-45 (M(0)) by laminin adhesion method in vitro. Tiam 1 ASODN was transfected into M(H) cells with liposome, and the expression of Tiam 1 mRNA and protein was determined by RT-PCR and flowcytometry respectively. The changes in morphology, the invasive and migratory potential between Tima 1 ASODN transfected M(H) cells and no transfected M(H) cells were observed by HE stain, cytoskeletal protein stain, scanning electronic microscope (SEM) and Boyden chamber test. RESULTS: Compared with the control, the expression of Tiam 1 mRNA and protein in M(H) cells was significantly decreased after transfected with 0.43 micromol/L ASODN(P< 0.01). The invasive and migratory potential of M(H) cells in vitro was also much more decreased than that of no transfected cells (P< 0.05 or P< 0.01). At the same time, transfected M(H) cells had less membrane surface projections, fewer or shorter pseudopodia, less irregular cytoskeletal network and less spotted-like actin bodys than no transfected M(H) cells did. CONCLUSION: Tiam 1 ASODN transfection can effectively suppress the expression of Tiam 1 in gastric cancer cells and impair its invasive and migratory potential in vitro, which may be fulfilled through modulating the reconstruction of cytoskeleton and decreasing the deforming and migratory potential of gastric cancer cells.
