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The enthalpy of formation and combustion is calculated for 15 aliphatic amines by various methods. These characteristics depend on the number of carbon atoms and the number of amino groups in the amine molecule. The combustion parameters are calculated when P = 1 atm and V = const, for mixtures of aliphatic amines with air. The adiabatic combustion temperature of mixtures of limiting composition is practically independent of the amine structure. The calculated values of the maximum pressure exceed 1000 kPa. 相似文献
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Strashilov Vesseline L. Alexieva Gergana E. Velichkov Velitchko N. Avramov Ivan D. Evans Stephen D. 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2009,56(5):1018-1023
A 1 GHz surface transverse wave resonator on 36° Y-cut quartz plate coated with organothiol-functionalized gold nanoparticle film has been studied as a chemical gas sensor. Considerable sensitivity of the resonant frequency to vapors of ethanol, methanol, chloroform, and acetic acid has been found. Owing to the high short-term stability of the oscillator built, the detection limit is in the low ppm range. The results qualitatively confirm previous results on the same film type obtained by conductivity measurements. In the present case, the conductivity effect resulting from variable separation of nanoparticles is accompanied with surface-attached mass of the absorbed gas. The film matrix exhibits considerable capacity to absorb large amounts of molecules at high gas concentrations. 相似文献
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Gergana I. Drandova Troy C. Messina Jae-Hyuk Choi Javier F. Hernandez John T. Markert 《Journal of Low Temperature Physics》2003,131(3-4):305-309
We report NMR lineshape, spin-lattice relaxation time T
1, and spin-spin relaxation time T
2 data at 17 MHz (8.07 T) for 89Y in the copper-oxide spin-chain compound Ca2+x
Y2–x
Cu5O10. For x=0, a broad, asymmetric line with width 90 kHz is observed for T=250–300 K. The spectra exhibit an appreciable average shift (H/H+0.7%) and sharpen at lower temperature, possibly due to increasing intrachain ferromagnetic correlations. T
1 and T
2 decrease with decreasing temperature. The Tl data imply a short correlation-time limit, with e=3–5×10–11 s. The T
2 data apparently include a contribution from dipolar interactions with copper nuclei. Relaxation time data for a doped (x=0.5) compound surprisingly show more rapid relaxation. 相似文献
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The kinetics and mechanism of chemical reactions in detonation waves propagating in mixtures of nitric acid with nitroglycol, ethylene glycol dinitrate, and acetic anhydride were studied within the framework of the Dremin—Trofimov theory of the detonation failure diameter. The state parameters in shock and detonation waves were calculated using the SGKR software package. It was shown that the decomposition of mixtures of nitric acid with organic substances in a detonation wave is a complex reaction which includes several stages. Various kinetic models are considered; effective values of the kinetic parameters are calculated for each model and for the entire process. 相似文献
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Katya Georgieva Gergana Mihailova Beatriz Fernndez-Marín Gianpaolo Bertazza Annalisa Govoni Miren Irati Arzac Jos Manuel Laza Jos Luis Vilas Jos Ignacio García-Plazaola Francesca Rapparini 《International journal of molecular sciences》2022,23(23)
Resurrection plants are able to deal with complete dehydration of their leaves and then recover normal metabolic activity after rehydration. Only a few resurrection species are exposed to freezing temperatures in their natural environments, making them interesting models to study the key metabolic adjustments of freezing tolerances. Here, we investigate the effect of cold and freezing temperatures on physiological and biochemical changes in the leaves of Haberlea rhodopensis under natural and controlled environmental conditions. Our data shows that leaf water content affects its thermodynamical properties during vitrification under low temperatures. The changes in membrane lipid composition, accumulation of sugars, and synthesis of stress-induced proteins were significantly activated during the adaptation of H. rhodopensis to both cold and freezing temperatures. In particular, the freezing tolerance of H. rhodopensis relies on a sucrose/hexoses ratio in favor of hexoses during cold acclimation, while there is a shift in favor of sucrose upon exposure to freezing temperatures, especially evident when leaf desiccation is relevant. This pattern was paralleled by an elevated ratio of unsaturated/saturated fatty acids and significant quantitative and compositional changes in stress-induced proteins, namely dehydrins and early light-induced proteins (ELIPs). Taken together, our data indicate that common responses of H. rhodopensis plants to low temperature and desiccation involve the accumulation of sugars and upregulation of dehydrins/ELIP protein expression. Further studies on the molecular mechanisms underlying freezing tolerance (genes and genetic regulatory mechanisms) may help breeders to improve the resistance of crop plants. 相似文献
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The detonation failure diameter was determined for mixtures of dinitrotoluene in concentrated nitric acid with zero and negative
oxygen balance in flat glass dishes. For mixtures with negative oxygen balance, detonation was detected in layers 0.10 and
0.12 mm thick, and detonation failure took place in layers 0.08 mm thick. The data obtained gives complete form to the dependence
of the detonation failure diameter on composition for dinitrotoluene solutions in HNO3.
Translated fromFizika Goreniya i Vzryva, Vol. 35, No. 5, pp. 113–115, September–October 1999. 相似文献
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