𝔖 Bobbio Scriptorium
✦   LIBER   ✦

Retardation of setting of plaster of Paris by organic acids: Understanding the mechanism through molecular modeling

✍ Scribed by Jörg-Rüdiger Hill; Johann Plank

Publisher
John Wiley and Sons
Year
2004
Tongue
English
Weight
231 KB
Volume
25
Category
Article
ISSN
0192-8651

No coin nor oath required. For personal study only.

✦ Synopsis

Abstract

To develop an understanding of the action of specific formulations, the growth of gypsum crystals under the influence of retardation agents (tartaric and citric acid) has been studied using molecular modeling. Surface energies of gypsum and plaster crystal faces were calculated using established protocols. The crystal morphology predicted for gypsum crystals in the absence of retardation agents is in excellent agreement with experiment. The simulations show that only in an alkaline environment is the crystal morphology of gypsum changed by retardation agents. The simulations provide a detailed description of retardation, for example, the specific mechanisms by which tartaric and citric acid retard setting of gypsum and how they differ. At high pH meso, D(−), and L(+) tartaric acid inhibit both the growth of gypsum and the dissolution of plaster while at low pH tartaric acid and citric acid will principally inhibit the growth of gypsum. The simulations provide a molecular rationalization for a range of experimental observations and a basis for the selection of alternate retardation agents. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 1438–1448, 2004

📜 SIMILAR VOLUMES

Toward understanding the inactivation me
Toward understanding the inactivation mechanism of monooxygenase P450 BM-3 by organic cosolvents: A molecular dynamics simulation study
✍ Danilo Roccatano; Tuck Seng Wong; Ulrich Schwaneberg; Martin Zacharias 📂 Article 📅 2006 🏛 Wiley (John Wiley & Sons) 🌐 English ⚖ 1000 KB

## Abstract Cytochrome P450 BM‐3 from __Bacillus megaterium__ is an extensively studied enzyme for industrial applications. A major focus of current protein engineering research is directed to improving the catalytic performance of P450 BM‐3 toward nonnatural substrates of industrial importance in

Towards an understanding of the molecula
Towards an understanding of the molecular mechanism of solvation of drug molecules: A thermodynamic approach by crystal lattice energy, sublimation, and solubility exemplified by hydroxybenzoic acids
✍ German L. Perlovich; Tatyana V. Volkova; Annette Bauer-Brandl 📂 Article 📅 2006 🏛 John Wiley and Sons 🌐 English ⚖ 241 KB

Temperature dependencies of saturated vapor pressure and heat capacities for the 2-, 3-, and 4-hydroxybenzoic acids were measured and thermodynamic functions of sublimation calculated (2-hydroxybenzoic acid: DeltaG(sub) (298) = 38.5 kJ/mol; DeltaH(sub) (298) = 96.6 +/- 0.8 kJ/mol; DeltaS(sub) (298)

Molecular mechanical models for organic
Molecular mechanical models for organic and biological systems going beyond the atom centered two body additive approximation: aqueous solution free energies of methanol and N-methyl acetamide, nucleic acid base, and amide hydrogen bonding and chloroform/water partition coefficients of the nucleic acid bases
✍ Piotr Cieplak; James Caldwell; Peter Kollman 📂 Article 📅 2001 🏛 John Wiley and Sons 🌐 English ⚖ 145 KB

## Abstract We have developed a methodology to derive RESP charges for molecular mechanical models that include “lone pairs” on lone‐pair donor sites and atom‐centered polarizabilities. This approach uses a very high level __ab initio__ cc‐pVTZ basis set,1 where the multipole moments of the molecul