Image1_The ionic salts with super oxidizing ions O2+ and N5+: Potential candidates for high-energy oxidants.TIF

As an important component of energetic materials, high-energy oxidant is one of the key materials to improve their energy. The oxidizability of oxidant directly determines the intensity of combustion or explosion reaction. It is generally believed that when the nature of reductant is certain, the stronger the oxidizability, the more intense the reaction. Dioxygenyl cation (O2+) and pentazenium cation (N5+) are two kinds of super oxidizing ions, which oxidizability are comparable to that of fluorine. A series of high energetic ionic salts with O2+, N5+ and various anions as active components are designed, and the results show that: 1) Most ionic salts have appropriate thermodynamic stability, high density (up to 2.201 g/cm3), high enthalpy of formation (up to 1863.234 kJ/mol) and excellent detonation properties (up to 10.83 km/s, 45.9 GPa); 2) The detonation velocity value of O2 (nitrotetrazole-N-oxides) and O2B(N3)4 exceed 10.0 km/s, and the detonation pressure exceed 45.0 GPa because of the O2+ salts have higher crystal density (g/cm3) and oxygen balance than that of N5+salts; 3) With a higher nitrogen content than O2+, the N5+ salts have higher enthalpy of formation, which exceed 330 kJ/mol than that of O2+ salts; 4) The linear spatial structure of N5+ leads the salts to reduce their density. Encouragingly, this study proves that these super oxidizing ions have the potential to become high-energy oxidants, which could be a theoretical reference for the design of new high energetic materials.</p

Can Catenated Nitrogen Compounds with Amine-like Structures Become Candidates for High-Energy-Density Compounds?

The worthwhile idea of whether amine-like catenated nitrogen compounds are stable enough to be used as high-energy materials was proposed and answered. Abstracting the NH3 structure into NR3 (R is the substituent) yields a new class of amine-like catenated nitrogen compounds. Most of the azole ring structures have a high nitrogen content and stability. Inspired by this idea, a series of new amine-like catenated nitrogen compounds (A1 to H5) were designed, and their basic energetic properties were calculated. The results showed that (1) amine-like molecular structures are often characterized by low density; however, the density of these compounds increases as the number of nitrogens in the azole ring increases; (2) these catenated nitrogen compounds generally have extremely high enthalpies of formation (882.91–2652.03 kJ/mol), and the detonation velocity of some compounds exceeds 9254.00 m/s; (3) the detonation performance of amine-like catenated nitrogen compounds designed based on imidazole and pyrazole rings is poor due to their low nitrogen content; and (4) the bond dissociation enthalpy of trigger bonds of most compounds is higher than 84 kJ/mol, indicating that these compounds have a certain thermodynamic stability. In summary, amine-like catenated nitrogen compounds have the potential to become energetic compounds with excellent detonation properties and should be considered to be synthesized by experimental chemists

MOESM1 of Thermogravimetric analysis, kinetic study, and pyrolysis–GC/MS analysis of 1,1ʹ-azobis-1,2,3-triazole and 4,4ʹ-azobis-1,2,4-triazole

Additional file 1. The purity of the title compounds

Ultrastructure of the glomerular basement membranes of the immunized animals after the <i>Y. pestis</i> challenge.

<p>The control animals infected with <i>Y. pestis</i> were observed under a transmission electron microscope. Transmission electron micrograph of the glomerular basement membrane (GBM) of the control animal that that were only immunized with aluminum hydroxide adjuvant and then infected with virulent <i>Y. pestis</i> strain 141 (a), the animal immunized with EV76 (b), the animal immunized with subunit vaccine SV1 (c), and the animal immunized with subunit vaccine SV2 (d).</p

Giemsa staining was done to visualize the bacteria in tissues.

<p>The bacteria were clearly visible within the tissues from the lungs, livers, kidneys, lymph nodes, brains, spleens, and blood from heart of the control animals that were only immunized with aluminum hydroxide adjuvant before they were infected with virulent <i>Y. pestis</i> strain 141. The lungs showed several large clumps of bacteria in the alveolar septum (a, arrows). Bacteria were also found inside blood vessels in the lungs (b, arrows) and blood from heart (d, arrows). Several large clumps of bacteria were shown in the hepatic sinus (c, arrows). Medullary cords of the lymph nodes were damaged and occupied by a large number of bacteria (e, arrows). The spleen show many large clumps of bacteria (f, arrows). Smaller clumps of bacteria are shown within the glomcrulus (g, arrows) and blood vessels in brain tissue (h, arrows).</p

Histopathology of the organs from the immunized animals, the control animals, and the naïve control animal.

<p>Tissue sections were stained with hematoxylin and eosin for pathological examination after infection with <i>Y. pestis</i>. (a) Tissue sections from the naïve control animal that was neither immunized with plague vaccines or aluminum hydroxide adjuvant nor infected with <i>Y. pestis</i>. (b) Tissue sections from the control animal that only received aluminum hydroxide adjuvant before it was infected by virulent <i>Y. pestis</i> strain 141. (c) Tissue sections from the animals immunized with SV1 and then infected with virulent <i>Y. pestis</i> strain 141. (d) Tissue sections from the animals immunized with SV2 and then infected with virulent <i>Y. pestis</i> strain 141. (e) Tissue sections from the animals immunized with EV76 and then infected with virulent <i>Y. pestis</i> strain 141.</p

The F1 antigen of <i>Y. pestis</i> was identified by Immunohistochemitry staining.

<p>The F1 antigen of <i>Y. pestis</i> was identified by Immunohistochemitry staining in formalin-fixed paraffin-embedded tissues from the control animals that were only immunized with aluminum hydroxide adjuvant and then infected with virulent <i>Y. pestis</i> strain 141. The sections were incubated for 12 h with the purified rabbit anti-F1 antigen of <i>Y. pestis</i> polyclonal antibody at 4°C, and incubated for 10–20 min with the polyperoxidase-anti-rabbit IgG at 37°C. The slides were stained with 3, 3′-diaminobenzidine tetrahydrochloride (DAB). Finally, the sections were rinsed, counterstained, dehydrated, cleaned, mounted and examined by light microscopy. Bacteria were visualized as those expressing F1 antigen (brown and yellow stain). Numerous bacteria were observed in the tissues of the lymph node (a), spleen (b), liver (c), kidneys (d) or lungs (e). No bacterium was found in the control spleen (f).</p

Transmission electron micrographs of the organs of the control animals.

<p>Transmission electron micrographs of the lymph nodes, spleen, liver, and lungs of the control animals that were only immunized with aluminum hydroxide adjuvant and then infected with virulent <i>Y. pestis</i> strain 141. The tissues were fixed in 3.1% glutaraldehyde solution and then postfixed in 1% osmium tetroxide. Afterwards, the tissue samples were dehydrated with a serial alcohol gradient, and then embedded in Epon812. Ultrathin sections were stained with uranyl acetate and lead citrate and examined under a Philips Tecnai 10 transmission electron microscope. Ultrastructural examination shows that lymph node tissue structures were destroyed and a large number of bacteria are found in the interstitium (a). The Splenic pulp shows a large number of bacteria and its structure was destroyed (b). A large number of bacteria are found around Kupffer's cells (c). Three <i>Y. pestis</i> were observed in blood vessel of lungs (d).</p