Energetic [1,2,5]oxadiazolo [2,3-a]pyrimidin-8-ium Perchlorates: Synthesis and Characterization.

A convenient method to access the above perchlorates has been developed, based on the cyclocondensation of 3-aminofurazans with 1,3-diketones in the presence of HClO4. All compounds were fully characterized by multinuclear NMR spectroscopy and X-ray crystal structure determinations. Initial safety testing (impact and friction sensitivity) and thermal stability measurements (DSC/DTA) were also carried out. Energetic performance was calculated by using the PILEM code based on calculated enthalpies of formation and experimental densities at r.t. These salts exhibit excellent burn rates and combustion behavior and are promising ingredients for energetic materials.

Solvate of 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-Hexaazaisowurtzitane (CL-20) with both N2 O4 and Stable NO2 Free Radical.

A new solvate of a powerful explosive 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and liquid oxidizer N2 O4 has been synthesized. When stored at room temperature, the white crystals turn yellowish brown, which indicates partial dissociation of N2 O4 with the formation of a stable NO2 free radical, which is confirmed by ESR spectroscopy. The resulting solvate was analyzed by powder X-ray diffraction, IR-spectroscopy, differential scanning calorimetry and thermogravimetric analysis. The vapor pressure of NO2 above the solvate crystals is similar to the pressure above common hydrates. The presence of the NO2 radical does not affect the thermal stability of CL-20. However, under closed conditions, NO2 increases the rate of the autocatalytic decomposition reaction. The kinetics of this reaction at the surface temperature determine the burning rate of the solvate. The novel solvate has a high density (1.98 g cm-3 ), a high predicted detonation velocity and pressure, and sensitivity to impact slightly higher to that of ϵ-CL-20.

Septoplasty retards midfacial growth in a rabbit model.

OBJECTIVES/HYPOTHESIS: Septoplasty in the prepubertal age group is a controversial operation because of concerns regarding retardation of subsequent midfacial growth. This study uses a validated rabbit snout model to determine if septoplasty results in midfacial growth retardation, and if the retardation can be averted by replacing resected cartilage with a porous polyethylene implant. STUDY DESIGN: Prospective controlled animal study. METHODS: Sixteen 9-week-old New Zealand white rabbits were divided into four groups: two control and two experimental. The experimental groups both underwent conservative submucoperichondrial surgical excision of a portion of their septum, leaving a generous dorsal and caudal septal strut for nasal support similar to what would be done clinically in humans. One of the experimental groups had replacement of the resected area by a rigid porous polyethylene graft, and in the other experimental group the resected area was left empty. Cephalometric measurements were performed on radiographs taken at the time of implantation, and at sacrifice when the rabbits were mature at 24 weeks of age. RESULTS: There were significant disturbances in snout growth between experimental and control groups, and no significant differences between the two experimental groups or between the two control groups. CONCLUSIONS: These data demonstrate midfacial growth retardation after conservative septoplasty in young rabbits, and that this retardation could not be averted by replacing the resected cartilage with a porous polyethylene graft. These data are in agreement with human studies.