Effects of pressure on structural, electronic, optical, and mechanical properties of nitrogen-rich energetic material: 6-azido-8-nitrotetrazolo[1,5-b]pyridazine-7-amine (3at).

CONTEXT AND RESULTS: 6-Azido-8-nitrotetrazolo[1,5-b]pyridazine-7-amine (3at) is a promising green energetic material, which meets the development requirements of environment-friendly explosives. By discussing the relationship between lattice parameters and pressure, it is found that the compression ratio indicates anisotropy of compressibility. And bond lengths get shorter under pressure, resulting in stronger intermolecular bonds. The N3 group rotates under pressure. And then, the optical properties basically change regularly with the change of pressure. As the pressure increases, the absorption range widens. In the low energy interval, it shows transparency, and then with the increase of energy and pressure, it shows better optical activity. With the increase of pressure and energy, the absorption coefficient increases, representing that the optical activity becomes high. Finally, according to the analysis of mechanical properties, 3at exhibited brittle behavior at 0 GPa and 100 GPa, while at 10 to 90 GPa, the values of ν and B/G are malleable. COMPUTATIONAL AND THEORETICAL TECHNIQUES: Based on density functional theory, the crystal parameters, electronic properties, optical properties, and elastic and mechanical properties of 3at under different pressures were studied theoretically. The GGA-PW91+OBS method was used to calculate the physical parameters under pressure, such as lattice parameters, energy band structures, dielectric function, refractive index, absorption coefficient, and elastic constants. Physical properties under (3at) pressure are predicted.

HMX/NMP cocrystal explosive: first-principles calculations.

The band structure, total density of states, and atomic orbit projected density of states analysis were performed to investigate HMX/NMP cocrystal by using the first-principles calculations. Results show that the HMX/NMP cocrystal is equipped with a direct band gap and the interactions between HMX and NMP molecules are rather weak. The O orbits hybridize with H orbits, and the parts of charge transform from H to O atoms by analyzing the DOS. The HMX/NMP cocrystal possesses three types of intermolecular interactions between HMX and NMP; these interactions and the arrangement of two molecules in the structure are the main reasons for the low sensitivity of the cocrystal. The C-H…O type hydrogen bond is the key role in forming the structure, and the strength of the hydrogen bond interaction for C-H…O-N is higher than that of C-H…O-C.

First-principles calculations of effects of pressure on paramagnetic, ferromagnetic, and antiferromagnetic spin-web Cu3TeO6.

The structure, electronic, and magnetic properties have been investigated by the first-principles calculations for paramagnetic, ferromagnetic, and antiferromagnetic Cu3TeO6 under pressure from 0 to 100 GPa. The calculated lattice parameters at 0 GPa are in excellent agreement with the available calculated and experimental values. With increasing pressure, the lattice parameters and volume decrease, but Cu3TeO6 keeps a stable cubic structure. The electronic calculations show that paramagnetic and ferromagnetic Cu3TeO6 are metallic, and antiferromagnetic Cu3TeO6 is non-metallic with a direct band gap which decreases with the increasing pressure. Under the pressure, their non-locality of density of states enhances and the electrons become more active. Moreover, for antiferromagnetic Cu3TeO6, the spin moments of Cu atoms are affected obviously by pressures, and Te atoms show nonmagnetic performance. The total magnetic moment, which is mainly contributed by Cu, reaches the maximum at 20 GPa, and decreases with the increasing pressure. The knowledge of these properties will provide reference and guidance for the subsequent study of Cu3TeO6.

The recruitment of exogenous endothelial progenitor cells in lung tumor model of nude mice.

BACKGROUND AND OBJECTIVE: Endothelial progenitor cells (EPCs) play an important role in hypoxia-triggered tumor vasculogenesis. However, the homing of exogenous EPCs in tumors is still unclear. In this study, we investigated the recruitment of exogenous EPCs in human lung adenocarcinoma model of nude mice. METHODS: EPCs labeled with green fluorescence protein (GFP) were transplanted into nude mice bearing human lung adenocarcinoma. The growth of tumor was observed. After the mice were killed, GFP-EPCs in different tissues were examined by fluorescence. The tumor tissues were stained for CD133, hypoxia-inducible factor-1alpha (HIF-1α), stromal cell-derived factor-1α (SDF-1α), and vascular endothelial growth factor receptor (KDR). Real-time polymerase chain reaction of CD133, HIF-1α, SDF-1α, and VEGF-1 were also performed. RESULTS: The growth of tumor in EPC group was significantly faster than that in saline solution group (P <0.05). Under fluorescence microscope, GFP-EPCs were strongly expressed in both tumor and bone marrow. EPCs were recruited to the tumor periphery to participate in tumor vasculogenesis. The expression of CD133, HIF-1α, and SDF-1 mRNA in tumor and bone marrow were significantly higher than that in the liver, spleen, and skin (P<0.05). CONCLUSIONS: Exogenous EPCs can be recruited to tumor and accelerate tumor growth. Except tumor, bone marrow can also recruit EPCs.

[Treatment of Hirschsprung disease by botulinum toxin A through anorectal injection].

OBJECTIVE: To investigate the feasibility and short- term effect of injecting botulinum toxin A through anorectum to treat Hirschsprung disease. METHODS: Eight cases with Hirschsprung disease were proven pathologically or diagnosed by barium enema. At the clock point of 3,6,9 under supine posture,a total dose of 1.5 U/ kg of botulinum toxin A was injected into the internal anal sphincter and the submucosa of rectum. The pressure of anus- rectum was measured before operation and 1 month,1 year after operation,respectively. Barium enema examination was carried out within 3-6 months after operation,then once a year during followed- up. RESULTS: All of the patients recovered well without operative or postoperative complications. In the first year,all patients could defecate spontaneously without constipation and abdominal distention. Three cases had constipation again and slight abdominal distention 1 year after operation,but the symptoms were relieved after anus dilatation. The resting pressure of anus- rectum was lower 1 month after operation than that before operation (P< 0.01) in 8 cases,and still lower 1 year after operation (P< 0.05)in 6 cases. Barium enema examination within 3-6 months after operation revealed that the dilated colon shrank. CONCLUSION: Botulinum toxin A injection is a new,feasible and safe method for Hirschsprung disease,but the long- term efficacy needs to be further studied.