An updated technique to obtain explosive kinetics data on microsecond timescales.

There are few techniques available for chemists to obtain time-to-explosion data with known temperature inputs at the early stages of the design and synthesis of new explosives. In the 1960s, a technique was developed to rapidly heat milligram-quantities of confined explosives to ∼1000 K on microsecond timescales. Wenograd [Trans. Faraday Soc. 57, 1612 (1961)] loaded explosives inside stainless steel hypodermic needles, connected them to a fireset and rapidly discharged a capacitor through the steel. He obtained the temperature by measuring the needle resistance in a Wheatstone bridge arrangement and the time to explosion from a needle rupture. However, owing to the narrow-gauge needles used in the original research, the experiment was only possible with melt-castable explosives; it was never replicated, and modern diagnostics are now available with advances beyond the 1960s. Here, we report the development of the High Explosives Initiation Time (HEIT) test, which utilizes a 250 J pulsed power system to heat the needles. This work extends the Wenograd approach by using optical diagnostics, computational modeling, and advanced techniques to measure needle resistance and needle rupture. Preliminary rate information for pentaerythritol tetranitrate (PETN) will be presented.

Large-Scale Analysis on Accelerated Aging of Pentaerythritol Tetranitrate (PETN) Powders in Detonators.

Pentaerythritol tetranitrate (PETN) has been used extensively in commercial detonators and other explosive applications for many decades. Here, we show the results of a comprehensive 1.5 year aging study of PETN in commercial detonators, addressing batch-to-batch variations, surface area changes, and comparisons of aged loose powders side-by-side with identically aged detonators. Function time analysis of the aged detonators has also been provided and discussed in the context of powder aging. This large-scale, statistically relevant study addresses long-standing questions on PETN aging without the complications from making comparisons between multiple batches of material. We have evaluated the aging time required to reach the maximum measured amount of PETN coarsening and estimated an activation barrier of ∼123 kJ mol-1, which is higher than literature values reported by Gee et al. It is possible that this discrepancy is due to the fact that that this study cannot quantify the relative contributions of surface diffusion versus sublimation processes. At the lower temperatures of 50 and 60 °C, we assume that surface diffusion dominates over sublimation processes, even at longer aging times. At the higher temperature of 75 °C, we assume that both surface diffusion and sublimation contribute at the early time points, which are included in the Arrhenius analysis for coarsening.

Complicaciones en el post-operatorio de la cirugía de la escoliosis y los cuidados de enfermería aplicados / Postoperative complication of the scoliosis surgery and applied nursing care

Se presenta un plan de atención de cuidados de enfermería elaborado en base a las complicaciones más frecuentes que se pueden presentar en el período post-operatorio de la cirugía de columna, especificamente de la escoliosis y se emplean los diagnósticos y estándares de enfermería según los problemas, reales o potenciales, del paciente. Los problemas se clasifican en pulmonares, hemodinámicos, neurológicos, urinarios, gastrointestinales, alergícos, e infecciosos