The lack of fundamental understanding of the intricate interplay between large amounts of chemical energy stored in energetic molecular materials and their sensitivity to detonation initiation represents a stubborn ou...
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The lack of fundamental understanding of the intricate interplay between large amounts of chemical energy stored in energetic molecular materials and their sensitivity to detonation initiation represents a stubborn outstanding challenge. This study sheds much needed light on the atomic decomposition mechanisms of nitroesters with an example of pentaerythritol tetranitrate (C5H8N4O12, also known as PETN), used as an explosive and a medication. The performed study is based on density functional theory combined with variational transition-state theory and large-scale massively parallel periodic supercell calculations and presents a detailed analysis of thermal initiation of chemical reactions and their kinetics in the gas-phase PETN molecules, the ideal bulk crystals, and on two low energy surfaces, (101) and (110). The obtained activation barriers, reaction energies, and reaction rates of simulated bond dissociation mechanisms reveal that the overall decomposition of condensed nitroesters is defined by the interplay of two major reactions, the fast endothermic O-NO2 homolysis and the slow exothermic HONO elimination. While the O-N cleavage has a low activation barrier and essentially initiates the degradation of the material, the HONO elimination pathway serves to accelerate the global process by generating heat to support the reaction. This trend is suggested to be general for a large class of traditional and novel nitroesters.
A simple analog locking circuit was shown to stabilize the beat signal between a 2.408 THz quantum cascade laser and a CH2DOH THz CO2 optically pumped molecular laser to 3-4 kHz (FWHM). This is approximately a tenth o...
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A simple analog locking circuit was shown to stabilize the beat signal between a 2.408 THz quantum cascade laser and a CH2DOH THz CO2 optically pumped molecular laser to 3-4 kHz (FWHM). This is approximately a tenth of the observed long-term (t similar to sec) linewidth of the optically pumped laser showing that the feedback loop corrects for much of the mechanical and acoustic-induced frequency jitter of the gas laser. The achieved stability should be sufficient to enable the use of THz quantum cascade lasers as transmitters in short-range coherent transceivers. (c) 2009 Optical Society of America
作者：
SOMER, EHAIFA UNIV
RD WOLFE CTR STUDY PSYCHOL STRESS MT CARMEL IL-31999 HAIFA ISRAEL
This paper presents a case involving a rape victim and her emotionally affected spouse. Although the assault occurred before the couple met, the husband was too upset to concentrate when the victim wanted to share her...
This paper presents a case involving a rape victim and her emotionally affected spouse. Although the assault occurred before the couple met, the husband was too upset to concentrate when the victim wanted to share her rape-related feelings, nor could he provide the much needed empathy and support. This, apparently, was due to his difficulties in handling his own rage. Simultaneous couple hypnotherapy was used to allow the victim to share her experience under conditions safe for both her and her spouse. As he imagined in trance the rape account described by his age-regressed wife, he learned to identify his emotions and experience them in a controlled manner. During subsequent sessions, the husband was encouraged to include himself in his wife''s abreaction and reshape the traumatic scene for both of them. The husbands'' rescuing behavior and the expressions of violent anger towards the perpetrator had several consequences. Not only did they change the abandonment component of the victim''s traumatic memory, but they also helped the husband deal in better ways with his own feelings of anger. It also provided the couple with a helpflul coping mechanism they later effectively applied under different circumstances.
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