scholarly journals GREEN CHEMICAL SYNTHESIS AND PROPERTIES OF SOLID DISPERSIONS OF BENZIMIDAZOLE –Β. NAPHTHOL BINARY DRUG SYSTEM

2018 ◽  
Vol 4 (2) ◽  
pp. 01-09
Author(s):  
H. Shekhar ◽  
Manoj Kumar
Keyword(s):  
Excess Entropy ◽  
Solid Dispersions ◽  
Boundary Energy ◽  
Roughness Parameter ◽  
Thermodynamic Quantities ◽  
Entropy Of Fusion ◽  
Chemical Technique ◽  
Binary Eutectic ◽  
Free Energy Of Mixing ◽  
Solid Liquid

With view to synthesize and characterize the enhanced pharmaceutical properties of the solid-liquid dispersions of binary drug system through green chemical technique the present communication have been undertaken for detailed investigation of thermodynamic and interfacial properties of benzimidazole (BI) and β. naphthol (βN) binary eutectic and non-eutectic drug dispersions. Eutectic solid dispersion was observed at 0.657 mole fraction of β. naphthol (βN) and at melting temperature 90°C. Thermodynamic quantities; Partial and Integral  excess Gibbs energy (gE), excess enthalpy (hE), excess entropy (sE) of eutectic and non-eutectic dispersions were determined with the help of activity coefficient data. The negative deviation from ideal behaviorhas been seen in the system which refers stronger association between unlike molecules during formation of binary mix. The negative value of Gibbs free energy of mixing (DGM) refers the mixing for all eutectic and non-eutectic dispersions is spontaneous. The solid-liquid interfacial characteristics i.e., entropy of fusion per unit volume (DSV), solid-liquid interfacial energy (s), roughness parameter (α), grain boundary energy and roughness parameter (α) of eutectic and non-eutectic solid dispersions have been reported. The size of critical nucleus at different undercoolings has been found in nanoscale, which may be a big significance in pharmaceutical world. The value of roughness parameter, α > 2 was observed which manifests the faceted and irregular growth leads in the system.

scholarly journals Solid–liquid equilibria, physicochemical and microstructural studies of binary organic eutectic alloy: urea + 2-aminobenzothiazole system

2012 ◽  
Vol 10 (10) ◽  
pp. 91-94 ◽  
Author(s):  
Krishna Prasad Sharma ◽  
Pawan Raj Shakya ◽  
Ramananda Rai
Keyword(s):  
Eutectic Alloy ◽  
Thermodynamic Functions ◽  
Roughness Parameter ◽  
Heat Of Mixing ◽  
Organic System ◽  
Thin Glass ◽  
Entropy Of Fusion ◽  
Characteristic Features ◽  
Solid Liquid Interface ◽  
Solid Liquid

Phase diagram of binary organic system of urea (U) with 2-aminobenzothiazole (ABT) shows the formation of a eutectic at 0.350 mole fraction of urea. Growth kinetics of the eutectic and pure components studied by measuring the rate of movement of solid-liquid interface in a thin glass U-tube at different undercoolings (ÄT) suggests the applicability of HilligTurnbull’s equation:  v = u (ÄT) n. The thermodynamic functions such as heat of mixing, entropy of fusion, roughness parameter, interfacial energy and excess thermodynamic functions were calculated from the enthalpy of fusion values, obtained from DSC data. The optical microphotographs of pure and eutectic alloy show their characteristic features. Scientific World, Vol. 10, No. 10, July 2012 p91-94 DOI: http://dx.doi.org/10.3126/sw.v10i10.6871

Higher Order Conditional Probabilities and Thermodynamics of Binary Molten Alloys

1997 ◽  
Vol 11 (02n03) ◽  
pp. 93-106 ◽  
Author(s):  
O. Akinlade
Keyword(s):  
Free Energy ◽  
Experimental Evidence ◽  
Cluster Model ◽  
Excess Free Energy ◽  
Higher Order ◽  
Thermodynamic Quantities ◽  
Equiatomic Composition ◽  
Conditional Probabilities ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing

The recently introduced four atom cluster model is used to obtain higher order conditional probabilities that describe the atomic correlations in some molten binary alloys. Although the excess free energy of mixing for all the systems studied are almost symmetrical about the equiatomic composition, most other thermodynamic quantities are not and thus, the study enables us to explain the subtle differences in their physical characteristics required to describe the mechanism of the observed strong heterocoordination in Au–Zn or homocoordination in Cu–Ni within the same framework. More importantly, we obtain all calculated quantities for the whole concentration range thus complimenting experimental evidence.

The rubidium chloride – sodium chloride phase diagram

1970 ◽  
Vol 48 (22) ◽  
pp. 3483-3486 ◽  
Author(s):  
A. D. Pelton ◽  
S. N. Flengas
Keyword(s):  
Phase Diagram ◽  
Free Energy ◽  
Sodium Chloride ◽  
Excess Entropy ◽  
Excess Free Energy ◽  
Thermochemical Data ◽  
Cooling Curves ◽  
Molar Excess ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing

The phase diagram of the RbCl–NaCl system has been measured by the method of cooling curves. By combining these data with available thermochemical data for the system, the integral molar excess free energy of mixing at 800 °C has been calculated as ΔGE = −632XRbClXNaCl cal/mole; and the integral molar excess entropy of mixing has been calculated as ΔSE = −0.208XRbClXNaCl cal/°K mole. Estimated precisions are ±50 cal for ΔGE and ±0.05 cal/°K mole for ΔSE at XRbCl = XNaCl = 0.5.

scholarly journals Thermodynamic study of binary mixture of citric acid and tartaric acid

2012 ◽  
Vol 10 (5) ◽  
pp. 1584-1589 ◽  
Author(s):  
Viorica Meltzer ◽  
Elena Pincu
Keyword(s):  
Phase Diagram ◽  
Differential Scanning Calorimetry ◽  
Citric Acid ◽  
Binary Mixture ◽  
Tartaric Acid ◽  
Heat Of Mixing ◽  
Scanning Calorimetry ◽  
Entropy Of Fusion ◽  
Excess Thermodynamic Functions ◽  
Solid Liquid

AbstractThe solid — liquid phase equilibria for binary mixture of citric acid with tartaric acid were measured using differential scanning calorimetry. The phase diagram showed the existence a simple eutectic behavior. The thermal properties of this system as heat of mixing, entropy of fusion and excess thermodynamic functions were computed using enthalpy of fusion values. The composition of eutectic was determined using a Tammann diagram.

Effect of High Rotating Magnetic Field on the Solidified Structure of Al–7wt.%Si–1wt.%Fe Alloy

2013 ◽  
Vol 752 ◽  
pp. 57-65 ◽  
Author(s):  
András Roósz ◽  
Jenő Kovács ◽  
Arnold Rónaföldi ◽  
Árpád Kovács
Keyword(s):  
Magnetic Field ◽  
Interface Velocity ◽  
Longitudinal Section ◽  
Rotating Magnetic Field ◽  
Christmas Tree ◽  
Binary Eutectic ◽  
Si Content ◽  
The One ◽  
Solid Liquid Interface ◽  
Solid Liquid

Al–7wt.-% Si–1wt.-% Fe alloy was solidified unidirectionally in the Crystallizer with High Rotating Magnetic Field (CHRMF). The diameter of sample was 8 mm and its length was 120 mm. The parameters of solidification were as follows: solid/liquid interface velocity ~0.082 mm/s, temperature gradient 7+/-1 K/mm, magnetic induction 0 and 150 mT, frequency of magnetic field 0 and 50 Hz. The structure solidified without rotating magnetic field (RMF) showed a homogeneous, columnar dendritic one. The structure solidified by using magnetic stirring showed a dual periodicity. On the one hand, the branches of the “Christmas tree”-like structure known from the earlier experiments contained Al+Si binary eutectic. On the other hand, bands with higher Fe- and Si-content formed in the sample, which were at a larger distance from each other than the branches of the “Christmas tree” structure. The developed microstructure was analyzed by SEM with EDS. The average Si- and Fe-concentrations were measured on the longitudinal section at given places along the length of sample. Furthermore the Si- and the Fe-concentrations close to the bands and among the bands as well as the composition of the compound phases were determined.

scholarly journals Lamellar Spacings Determined by Solid-Liquid Interfacial Morphology of Unidirectionally Solidified Al-Base Binary Eutectic Alloys

1993 ◽  
Vol 57 (9) ◽  
pp. 1054-1063
Author(s):  
Kazumitsu Shinohara ◽  
Toshihiro Seo ◽  
Takashi Naohara ◽  
Noriaki Sugamoto ◽  
Yuji Tadokoro
Keyword(s):  
Eutectic Alloys ◽  
Interfacial Morphology ◽  
Binary Eutectic ◽  
Solid Liquid

scholarly journals Theoretical assessment on hetero-coordination of Alloys Silver-Antimony at Molten State

2020 ◽  
pp. 68-73
Author(s):  
Narayan Panthi ◽  
Indra Bahadur Bhandari ◽  
Ishwar Koirala
Keyword(s):  
Reasonable Agreement ◽  
Chemical Activity ◽  
Heat Of Mixing ◽  
Thermodynamic Quantities ◽  
Molten State ◽  
Energy Of Mixing ◽  
Interchange Energy ◽  
Free Energy Of Mixing ◽  
Experimental Values ◽  
Theoretical Assessment

The thermodynamic and structural properties of binary alloy Ag- Sb at temperature 1250K have been reported theoretically using quasi lattice model. The interchange energy has been considered a function of a temperature and thus various thermodynamic quantities are calculated at elevated temperature. The theoretical values of free energy of mixing, heat of mixing, entropy of mixing and chemical activity are reasonable agreement with experimental values in all concentrations of antimony from 0.1 to 0.9. The theoretical analysis tells that the alloy shows both ordering nature in Ag rich end and segregating nature in Sb rich end .The study reveals that the properties of alloy are asymmetric around equi-atomic composition. The Ag_3 Sn complexes are most likely to exist in the liquid state and are moderately interacting.

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