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Abstract  

In order to predict extraction equilibria for uranyl nitrate and nitric acid between aqueous and tributyl phosphate (TBP)-hydrocarbon diluent solutions, activity coefficient equations for the three components in the system HNO3-UO2(NO3)2-H2O were derived and the general equation for excess Gibbs energy, proposed by Clegg and Pitzer, simplified. The activity coefficient equations comprise a Debye-Hückel term and a Margules expansion carried out to the four suffix level, where the higher order electrostatic contribution was neglected. The binary parameter was determined from the thermodynamic properties of the two relevant aqueous solutions. The three mixing parameters were obtained by correlating data for the partial pressure of nitric acid over HNO3-UO2(NO3)2-H2O solutions at 298.15 K. By using the mixing parameters, the activity coefficients of the ternary system can be calculated with good accuracy, and the solubility of uranyl nitrate in aqueous nitric acid with concentration up to 14 mol/kg can be satisfactorily predicted.

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Abstract  

In order to obtain the exact information of atomic number density in the ternary system of HNO3−UO2(NO3)2−H2O, the densities were measured with an Anton-Paar DMA60/602 digital density meter thermostated at 298.15±0.01 K. The apparent molal volumes for the systems were calculated from the experimental data. The present measured apparent molar volumes have been fitted to the Pitzer ion-interaction model, which provides an adequate representation of the experimental data for mixed aqueous electrolyte solutions up to 6.2 mol/kg ionic strength. This fit yields θV, and ψV, which are the first derivatives with respect to pressure of the mixing interaction parameters for the excess free energy. With the mixing parameters θV, and ψV, the densities and apparent molar volumes of the ternary system studied in this work can be calculated with good accuracy, as shown by the standard deviations.

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Abstract

This paper investigates the historical development during the past three centuries of the English suffix -en, used to create denominal adjectives (e.g. golden, silken), focusing on words that have remained in the language until the present day. We specify a way of calculating the rate of loss of the suffix and apply this to different lexical items involved in this process. Finally, we explore the roles of word frequency and collocations, in order to shed some light on how these factors relate to the loss of a linguistic form.

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Journal of Thermal Analysis and Calorimetry
Authors: Liang Xue, Feng-Qi Zhao, Xiao-Ling Xing, Zhi-Ming Zhou, Kai Wang, Hong-Xu Gao, Jian-Hua Yi, and Rong-Zu Hu

Abstract

The thermal decomposition behavior of 3,4,5-triamino-1,2,4-triazole dinitramide was measured using a C-500 type Calvet microcalorimeter at four different temperatures under atmospheric pressure. The apparent activation energy and pre-exponential factor of the exothermic decomposition reaction are 165.57 kJ mol−1 and 1018.04s−1, respectively. The critical temperature of thermal explosion is 431.71 K. The entropy of activation (ΔS ), enthalpy of activation (ΔH ), and free energy of activation (ΔG ) are 97.19 J mol−1K−1, 161.90 kJ mol−1, and 118.98 kJ mol−1, respectively. The self-accelerating decomposition temperature (T SADT) is 422.28 K. The specific heat capacity of 3,4,5-triamino-1,2,4-triazole dinitramide was determined with a micro-DSC method and a theoretical calculation method. Specific heat capacity (J g−1K−1) equation is C p = 0.252 + 3.131 × 10−3 T (283.1 K < T < 353.2 K). The molar heat capacity of 3,4,5-triamino-1,2,4-triazole dinitramide is 264.52 J mol−1 K−1 at 298.15 K. The adiabatic time-to-explosion of 3,4,5-triamino-1,2,4-triazole dinitramide is calculated to be a certain value between 123.36 and 128.56 s.

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Journal of Thermal Analysis and Calorimetry
Authors: Liang Xue, Feng-Qi Zhao, Xiao-Ling Xing, Zhi-Ming Zhou, Kai Wang, Hong-Xu Gao, Jian-Hua Yi, Si-Yu Xu, and Rong-Zu Hu

Abstract

The thermal decomposition behaviors of 1,2,3-triazole nitrate were studied using a Calvet Microcalorimeter at four different heating rates. Its apparent activation energy and pre-exponential factor of exothermic decomposition reaction are 133.77 kJ mol−1 and 1014.58 s−1, respectively. The critical temperature of thermal explosion is 374.97 K. The entropy of activation (ΔS ), the enthalpy of activation (ΔH ), and the free energy of activation (ΔG ) of the decomposition reaction are 23.88 J mol−1 K−1, 130.62 kJ mol−1, and 121.55 kJ mol−1, respectively. The self-accelerating decomposition temperature (T SADT) is 368.65 K. The specific heat capacity was determined by a Micro-DSC method and a theoretical calculation method. Specific heat capacity equation is (283.1 K < T < 353.2 K). The adiabatic time-to-explosion is calculated to be a certain value between 98.82 and 100.00 s. The critical temperature of hot-spot initiation is 637.14 K, and the characteristic drop height of impact sensitivity (H 50) is 9.16 cm.

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