Derived thermodynamic properties of [o-xylene or p-xylene + (acetic acid or tetrahydro-furan)] at different temperatures and pressures

Thermal expansion coefficients α, their excess values , isothermal coefficient of pressure excess molar enthalpy , partial molar volumes and excess partial molar volumes , were calculated from experimental densities. The isothermal coefficients of pressure excess molar enthalpy for binary mixtures {o-xylene or p-xylene + acetic acid} at temperatures 313.15-473.15 K and pressure 0.2-2 MPa are negative and for binary mixtures {o-xylene or p-xylene + tetrahydrofuran (THF)} at temperatures 278. 15 K to 318.15 K and pressure 81.5 kPa are negative and with increasing temperature become more negative. The excess thermal expansions coefficient , for binary mixtures {o-xylene or p-xylene + acetic acid} at temperatures 313.15-473.15 K and pressure 0.2 MPa and 2 MPa are positive. The excess thermal expansions coefficient for binary mixtures {o-xylene or p-xylene + tetrahydrofuran (THF)} at temperatures 278.15-318.15 K and pressure 81.5 kPa are positive and with increasing temperature become more positive. The excess molar volumes were correlated with a Redlich–Kister type equation.KEY WORDS: Thermal expansion coefficients, Isothermal coefficient, Excess partial molar volumes Bull. Chem. Soc. Ethiop. 2011, 25(2), 273-286.

Multi-Module G2P Converter for Persian Focusing on Relations between Words

In this paper, we investigate the application of end-to-end and multi-module frameworks for G2P conversion for the Persian language. The results demonstrate that our proposed multi-module G2P system outperforms our end-to-end systems in terms of accuracy and speed. The system consists of a pronunciation dictionary as our look-up table, along with separate models to handle homographs, OOVs and ezafe in Persian created using GRU and Transformer architectures. The system is sequence-level rather than word-level, which allows it to effectively capture the unwritten relations between words (cross-word information) necessary for homograph disambiguation and ezafe recognition without the need for any pre-processing. After evaluation, our system achieved a 94.48% word-level accuracy, outperforming the previous G2P systems for Persian.Comment: 10 pages, 4 figure

Theoretical studies of 31P NMR spectral properties of phosphanes and related compounds in solution

Selected theoretical methods, basis sets and solvation models have been tested in their ability to predict 31P NMR chemical shifts of large phosphorous-containing molecular systems in solution. The most efficient strategy was found to involve NMR shift calculations at the GIAO-MPW1K/6-311++G(2d,2p)//MPW1K/6-31G(d) level in combination with a dual solvation model including the explicit consideration of single solvent molecules and a continuum (PCM) solvation model. For larger systems it has also been established that reliable 31P shift predictions require Boltzmann averaging over all accessible conformations in solution

17O NMR parameters of some substituted benzyl ethers components: Ab initio study

The 17O NMR chemical shielding tensors and chemical shift for a set of substituted benzyl ethers derivatives containing (methyl, ethyl, isopropyl, t-butyl, brome and lithium) have been calculated. The molecular structures were fully optimized using B3LYP/6-31G(d,p). The calculation of the 17O shielding tensors employed the GAUSSIAN 98 implementation of the gauge-including atomic orbital (GIAO) and continuous set of gauge transformations (CSGT) by using 6-31G (d,p), 6-31++G(d,p) and 6-311++G(d,p) basis set methods at density functional levels of theories (DFT). The values determined using the GIAO and CSGT were found to give a good agreement with the experimental chemical shielding

Investigation of the interaction of 5-fluorouracil anticancer drug connected to the pristine, titanium doped boron phosphide nanocage (B12P12) with adenine nucleobases: by density functional theory

The aims of this work, is to investigate the adsorption of 5-Fluorouracil drug connected to the pristine, Titanium doped boron phosphide nanocage (B12P12) with adenine nucleobases by using density functional theory (DFT). For this means at the first step, we considered different configurations for adsorbing (5-FU) on the surface of nanocluster and adenine, and then all considered models are optimized at the WB97XD/Lanl2DZ level of theory by Gaussian (09) software. From optimized structures, geometrical parameters involve bond length and bond angle, thermodynamic, atom in molecule (AIM), reduced density gradient (RDG), Uv-visible spectrum, HOMO-LUMO orbitals, density of states (DOS), and quantum parameters are calculated and all results are analyzed. The calculated results reveal that in the Ti doped B12P12 nano cage, the gap energy and global hardness of system decrease significantly, and so the conductivity and reactivity of system increase from original state. This property is favorable for making sensitive sensor for this drug. The adsorption energy and enthalpy values for all studied models are negative, which indicate that the absorption process and their thermodynamic stability are favorable. The RDG and AIM results confirm that the adsorption of 5-FU drug connected to the nanocage with adenine is non-covalent type. The computational results demonstrate that the pristine and Ti–doped B12P12 can be used as a suitable candidate for fabricating detector and absorber for 5-FU drug

Excess thermodynamic parameters for binary and ternary mixtures of {1-butanol (1) + cyclohexylamine (2) + n-heptane (3)} at different temperatures: A theoretical study

In this work, we used the experimental data of Kijevcanin et al. for determining the excess thermodynamic parameters such as excess thermal expansion coefficients αE, isothermal coefficient of pressure excess molar enthalpy (∂HmE/∂P)T and excess partial molar volumes V¯m,iE for the binary and ternary mixtures formed by {1-butanol + cyclohexylamine + n-heptanes} at (288.15–323.15) K. The αE values, for 1-butanol + cyclohexylamine are S-shaped and for 1-butanol + n-heptane are positive and for cyclohexylamine + n-heptane are negative over the mole fraction range. The (∂HmE/∂P)T values, for 1-butanol + cyclohexylamine are S-shaped and for binary mixture of 1-butanol + n-heptane are negative and for binary mixture of cyclohexylamine + n-heptane are positive over the mole fraction. The values of αE and (∂HmE/∂P)T are calculated by using the Flory theory, the results show a good agreement with experimental data. The values of αE and (∂HmE/∂P)T for ternary mixture {1-butanol + cyclohexylamine + n-heptanes} are determined and the experimental data are correlated as a function of the mole fraction by using the equations of Cibulka, Jasinski and Malanowski, Singe et al., Pintos et al., Calvo et al., Kohler, and Jacob–Fitzner. The results show that the Calvo et al. equation is better than others

The effects of Isoniazid drug adsorption on the structural and electrical properties of pristine and Ni doped (6, 0) zigzag gallium nitride nanotube: By DFT method

The aims of this project are to investigate the effects of Isoniazid drug adsorption on the geometrical and electrical structure of pristine and Ni-doped Gallium nitride nanotube (GaNNTs). For this purpose, 24  different configuration models are considered  for adsorbing Isoniazid on the surface of nanotube and then all considered structures are optimized by using density function theory (DFT) at the Cam-B3LYP/6-31G (d) level of theory. By using optimized structures ,the structural parameters involve bond length and bond angle, HOMO and LUMO orbital, Density of state (DOS) plots, Quantum parameters, Natural bonding orbital (NBO), Atom in molecule (AIM), and Molecular electrostatic potential (MEP)  are calculated by above level of theory and all results are analyzed. The results reveal that doping Ni atom and adsorbing Isoniazid molecule decrease the energy gap and global hardness of nanotube and thereby the electrical properties of system increase, this property is suitable to making nano sensors. At all adsorption models the values of adsorption energy is negative and show that the adsorption process is exothermic and stable in thermodynamic approach. On the other hand, the adsorption of Isoniazid on the surface of nanotube is physical adsorption. Comparison the thermodynamic properties demonstrate that the Ni-doped decrease the Isoniazid adsorption on the surface of nanotube therefor the adsorption of Isoniazid on the surface of the Ni-doped models is not favorable than pristine models. In addition, the adsorption of Isoniazid on the surface of nanotube is physical adsorption.  &nbsp

<b>Derived thermodynamic properties of [<i>o</i>-xylene or <i>p</i>-xylene + (acetic acid or tetrahydro-furan)] at different temperatures and pressures</b>

Thermal expansion coefficients , their excess values , isothermal coefficient of pressure excess molar enthalpy , partial molar volumes and excess partial molar volumes , were calculated from experimental densities. The isothermal coefficients of pressure excess molar enthalpy for binary mixtures {o-xylene or p-xylene + acetic acid} at temperatures 313.15-473.15 K and pressure 0.2-2 MPa are negative and for binary mixtures {o-xylene or p-xylene + tetrahydrofuran (THF)} at temperatures 278. 15 K to 318.15 K and pressure 81.5 kPa are negative and with increasing temperature become more negative. The excess thermal expansions coefficient , for binary mixtures {o-xylene or p-xylene + acetic acid} at temperatures 313.15-473.15 K and pressure 0.2 MPa and 2 MPa are positive. The excess thermal expansions coefficient for binary mixtures {o-xylene or p-xylene + tetrahydrofuran (THF)} at temperatures 278.15-318.15 K and pressure 81.5 kPa are positive and with increasing temperature become more positive. The excess molar volumes were correlated with a Redlich–Kister type equation