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Abstract  

The synthesis of superheavy elements is now a hot topic in nuclear physics. Alpha-decay and spontaneous fission are two main decay modes in heavy and superheavy regions. Theoretical studies on alpha radioactivity and spontaneous fission can provide useful information for experiments. We investigate the alpha-decay and spontaneous fission of heavy and superheavy nuclei with different models. This includes the alpha-decay energies, alpha decay half-lives, and half-lives of spontaneous fission. The theoretical alpha-decay half-lives are in good agreement with experimental ones. The calculated half-lives of spontaneous fission are in reasonable agreement with present data. The properties of unknown nuclei are predicted.

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ensemble averaging of properties. Its most common use is in the parametrization of total energy and derivatives thereof, although there have been extensions to other properties such as ground state properties. The cluster expansion of total energy has been

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Abstract  

The properties of the solid-state of drug substances are critical factors that determine the choice of an appropriate salt form for the development of the pharmaceutical formulation. The most relevant properties may affect the therapeutic efficacy, toxicity, bioavailability, pharmaceutical processing and stability. The salt form must fulfil the needs of the targeted formulation, be suitable for full-scale production and its solid-state properties maintained batchwise as well as over time. Comparison of the solid-state properties of different salt candidates may be quite complicated if each salt candidate exist as different solid phases: polymorphs, solvates or amorphous forms. Thermal analysis, microcalorimetry and combined techniques, X-ray diffraction, solubility, intrinsic dissolution, sorption-desorption and stability studies are basic techniques for the characterisation of the salt candidates. Some examples show the role of the salt form as well as the polymorphic form in the characteristics of the solid-state. Thermal analysis and combined techniques are efficient for the detection of unexpected phase transitions and for the comparison of the suitability of the salt candidates prepared for salt selection.

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Abstract

The phase transition of TiN from the NaCl structure to the CsCl structure is investigated by the first-principles plane wave pseudopotential density functional theory method, and the thermodynamic properties of the NaCl structures are obtained through the quasi-harmonic Debye model. It is found that the pressures for transition from the NaCl structure to the CsCl structure are 364.1 GPa (for GGA) and 322.2 (for LDA) from equal enthalpies. The calculated ground state properties such as equilibrium lattice constant, bulk modulus, and its pressure derivative are in good agreement with experimental and theoretical data of others. Moreover, the dependences of the relative volume V/V 0 on the pressure P, the Debye temperature ΘD, and heat capacity C V on the pressure P and temperature T, as well as the variation of the thermal expansion α with temperature and pressure are also successfully obtained.

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Abstract

A comprehensive first principle study of thermodynamic properties of MgN is reported within the density functional theory scheme. The ground state properties such as lattice constant, Bulk modulus etc. of MgN in rock-salt (RS) phase have been determined. The thermodynamical properties have been analyzed in the light of phonon density of states of MgN and its constituent atoms. The variation of lattice-specific heat with temperature obeys the classical Dulong–Petit’s law at high temperature while at low temperature it obeys Debye T 3 law. The phonon spectrum shows the presence of all positive phonons and zero phonon density of states at zero energy confirming a dynamically stabilized structure of MgN in RS phase.

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Abstract

We report ab initio calculations of the thermal properties for transition metal nitrides, hafnium and zirconium nitride at ambient and high pressures. The assessment of thermodynamical properties like lattice specific heat, vibrational energy, internal energy and entropy for two nitrides has been carried out. The basic calculations of ingredient phonon density of states for the determination of thermal properties have been done using density functional perturbation theory including external perturbations like strains and electric fields in periodic systems. The ground state properties such as equilibrium lattice constants and bulk modulus obtained for two nitrides are in good agreement with the available experimental value. The calculated pressure variation of the phonon density of states shows trend similar to the experimental pressure dependent Raman spectra. The lattice specific heat, internal energy, entropy and Helmholtz energy increases with pressure.

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Journal of Thermal Analysis and Calorimetry
Authors: Dhruthiman R. Mantheni, M. P. K. Maheswaram, Hany F. Sobhi, Naullage Indika Perera, Alan T. Riga, M. Ellen Matthews, and K. Alexander

versus temperature curve in °C revealed new electrical signatures of each drug. A very complete review was performed by Hilfiker et al. [ 2 ] on the relevance of solid state properties for pharmaceutical products but they did not include dielectric

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also has been used to assess the success of the crystallisation control approach in producing certain polymorphs [ 3 , 4 ] and certain crystal properties [ 5 – 7 ]. In addition, the obtained knowledge on the solid state properties of the API could

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Journal of Thermal Analysis and Calorimetry
Authors: Agna Hélia de Oliveira, Elisana Afonso de Moura, Márcia Ferraz Pinto, José Valdilânio Virgulino Procópio, Valmir Gomes de Souza, Fábio Santos de Souza, and Rui Oliveira Macêdo

Chemical structure of pentoxifylline The successful formulation of a stable and effective solid dosage form depends on the careful selection of the excipients [ 3 – 6 ] and on the characterization of solid-state

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]. Quite apart from this, research on charge trapping in polymers has opened up new approaches to the investigation of solid-state properties of materials. This was aided by the development of number of new methods, including thermally stimulated discharge

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