Sparkle model

This model can be improved by taking into account polarization effects in the ligand sphere. For this end the metal ion is considered as a point charge equal to its oxidation degree or formal charge, which is the sparkle model [446]. 

SMLC/AMl Sparkle Model for the Calculation of Lanthanide Complexes/... 

A sp basis is employed for these elements. Using the sparkle model. Only parameters for Mo are published and recommended for general use parameters for other TM elements are preliminary. Only parameters for Zn, Cd, and Hg are recommended for general use parameters for other TM elements are preliminary. ... 

A so-called sparkle model for europium(III) in the semiempirical Austin Model 1 (AMI) (Dewar et al. 1985) scheme was recently proposed (Andrade et al. 1994, 1995). Essentially the lanthanide ion is treated as a positive point charge together with a suitable repulsive potential to model core-valence interaction. 

Within models of the sparkle family the effect of the external Coulomb field does not reduce to the renormalization of the orbital energies as it is within the RLMO model (see above). By contrast, the electron distribution also changes when the ligand molecules are put into the field. We model this by classical polarizability. Accordingly the difference between effective charge on atom A in the complex (polarized) and that in the free ligand (non-polarized) is ... 

Another extensive group of works, described in the literature, focus on different physico-chemical aspects of the effervescence in sparkling wines to try to explain bubble formation (nucleation) and survival, both in the interior of the liquid and also at its surface. Some of these works even propose models constructed with fibers to simulate bubble formation and behaviour (Casey 1987, 1995, 2000 Jordan and Napper 1994 Liger-Belairetal. 1999, 2001, 2002, 2006 Liger-Belair 2005 Peron et al. 2000, 2001, 2004 Senee et al. 1999 Uzel et al. 2006 Tufaile et al. 2007 Voisin et al. 2005). 

Martinez-Rodriguez, A.J., Polo, M.C., and Carrascosa, A.V. (2001b). Stractural and ultrastractural changes in yeast cells during autolysis in a model wine system and in sparkling wines. Int. J. Food Microbiol, 71, 45-51. 

Souz et al. synthesized and structurally characterized a tetramer complex [Eu4(ETA)9(OH)3 (H20)3l (see Figure 2.42 [76], where ETA = ethyl 4,4,4-trifluoroacetoacetate. From these structural data, they calculated the ground-state geometry of the tetramer by using the Sparkle/AMl model. The emission spectrum shows that the Dq Fq transitions in the emission spectrum are consistent with the Eu + ion occupying four different sites in chemical environments of low symmetries. 

Apricot was used as a model for studies of fruit puree clarification. Various puree concentrations were treated for 30 min at 50° C with 0.4 cc/L, each, of commercial cellulase and pectinase enzyme and clarified by filtration through a 0.45(im pore size ceramic microfilter. Sparkling clear apricot juice was produced at flux rates from 90-190 L/m2h. Above 13° starting Brix. juice flux showed little increase with increasing starting Brix. Dissolved solids flux increased substantially with increasing starting Brix. Permeate remained clear and retained most of its flavor and aroma when concentrated by vacuum evaporation to 58° Brix. There appears to be some retention of enzymes by the filter. Retained enzymes were successfully utilized in a 4 h trial in which untreated puree was continuously added to retentate. in amounts equal to permeate removed, after startup on enzyme-treated puree. 

Fig. 1.12. Repetitive bubble formation on a microcavity in a tartrate microcrystal in a sparkling wine. Heterogeneous induced nucleation, according to the Casey model (1988)...

The RMl method (Recife Model 1, so named because it was developed at the Federal University of Pernambuco in Recife, Brazil) has exactly the same structure as AMI, but all 191 parameters for the atoms C, H, 0, N, S, P, F, Cl, Br, I were reevaluated using data from 1736 molecules (as compared with about 200 molecules used for AMI) [G. B. Rocha et al., J. Comput. Chem., 27, 1101 (2006) www.rml.sparkle.pro.br]. Since parameters are available for only 10 elements, RMl is less widely applicable than AMI or PM3. 

Freire, R. O., Rocha, G. B., Simas, A. M. (2006). Modeling rare earth complexes Sparkle/ PM3 parameters for thulium (III). Chem Phys Lett 425, 138-141. 

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