Instability index

If DSC data have been obtained for a pure material or a reaction mixture, several thermal stability indicators (ASTM E 1231-96) may be estimated from the data. These are adiabatic temperature rise, explosion potential, instantaneous power density, time to maximum rate, and NFPA instability index (Leggett 2002). 

A second and complimentary measure of lattice strain is the global instability index (GII) defined by Salinas-Sanchez et al. (1992) using eqn (12.2) ... 

Fig. 13.3. The phase diagram of Ao.33A o.67Mn03 (A = divalent cation, A = rare earth) as a function of temperature and the global instability index of the idealized perovskite structure. The points show the observed transition temperatures in various compounds. FMM = ferromagnetic metal, PMI = paramagnetic insulator, FMI = ferromagnetic insulator (from Rao et al. 1998).

Given the following amino acid sequence, estimate (ProtParam of ExPASy) its amino acid composition, numbers of charged residues, extinction coefficient, estimated half-life, and instability index of the protein. Elaborate briefly how extinction coefficient, half-life and instability index are estimated. 

PTFE Resin Reduction Ratio Range Specific Gravity Average Particle Size, pm Thermal Instability Index Extrusion Pressure, MPa Reduction Ratio Bulk Density... 

Figure 3 The variation in the Global Instability Index of Ln2BaCu05 as a function of the ionic radius of Ln. The line is a fitted second order equation. Nd adopts a different structure. (Figure 12.3 from The Chemical Bond in Inorganic Chemistry by Brown, David (2001)). (Ref. 3. Reproduced by permission of Oxford University Press)...

Many attempts have been made to characterize the stability of the colloidal state of asphalt at ordinary temperature on the basis of chemical analysis in generic groups. For example, a colloidal instability index has been defined as the ratio of the sum of the amounts in asphaltenes and flocculants (saturated oils) to the sum of the amounts in peptizers (resins) and solvents (aromatic oils) (66) ... 

For characterization of the overall structure stability of perovskites, the Global Instability Index (GII), has been proposed (Salinas-Sanchez et al., 1992 Lufaso and Woodward, 2001). GII is defined as ... 

There are no standard tests for measuring the onset of asphaltenes precipitation. Among the techniques and analytical methods frequently used to measure sediment and asphaltenes onset for the adjustment of different process parameters in the refineries are spot test (ASTM-D-4740-95) total sediment (ASTM-4870-96) solubility parameters, optical microscope light scattering (PORLA) peptization value (P-value) ° colloidal instability index (CII) coking index. ... 

From DISTACT distillation Colloidal Instability Index =... 

The standardised volatilities of the major metals between 1950 and the late 1980s has been estimated to be as follows copper (61.5), lead (65.6), zinc (86.1), tin (92.7), silver (108.8) and gold (116.9). Narrowing the period under consideration to the 1980s, however, reverses the positions of copper and lead. See, AME, op at p 148. This conclusion is supported by the price instability index calculated by UNCTAD (1992) this indicates lead prices as the least unstable of all LME prices in the 1986-91 period. 

Colloidal instability index (CII). This index expresses the stability of asphaltenes in terms of SARA (Saturates, Aromatics, Resins, Asphaltenes) fractions and is defined as the mass ratio between the sum of asphaltenes and unfavorable components of its stability in the oil, i.e., its flocculants (Saturates) and the sum of peptizing agents (aromatics and resins), which are components favorable to the stability of asphaltenes present in a specific oil (Asomaning, 2003) ... 

Structure Analysis and Prediction 11.1 The Global Instability Index... 

In the aristotype ABX3 perovskite stmcture, with Pm3m space group symmetry, there is a single free parameter, the cubic lattice parameter, a. A simple method to model the crystal stmcture is to determine the stmcture parameter(s), a in this case, that minimize(s) the Global Instability Index, G (Eq. (21) in [8]). 

Fig. 2 Bond valence sums of the ions and global instability index versus lattice parameter for the cubic perovskite SrTiOs...

The bond valence parameters, calculations of bond valences, and global instability index are more fully described in [8, sections 3, 8 and 11]. 

Fig. 4 SPuDS predicted (filled symbols) and observed (open symbols) global instability index for untilted cubic perovskites. Squares represent ABF3 and circles represent ABO3 perovskites...

The observed and predicted global instability index versus tolerance factor for untilted cubic ABX3 perovskites is shown in Fig. 4. As expected the G is smallest for compounds with a tolerance factor near 1. For unstrained structures the normal maximum value of G is 0.2 v.u., but here we see a number of compounds where G > 0.2. This can be explained in part by realizing that when t is significantly different than 1 the compounds can be classified as strained. The largest G observed (G = 0.47) is for KTa03 t = 1.08) which has shown on multiple occasions to be a cubic perovskite [13, 30, 31]. These studies used samples prepared with several synthetic techniques and both polycrystalline powders and single crystals have been examined, which support the accuracy of the crystal structure. 

Fig. 8 Global instability index for ordered cubic perovskites with SPuDS predicted with G optimized diamonds) and observed (open squares) structure...

F. 14 Contour plot of the SPuDS calculated global instability index with the lattice parameter a and fractional coordinate x for the La2Su207 pyrochlore. The white diamond with green outline represents the SPuDS predicted lattice parameter and Ifactiraial coradinate, respectively. The yellow square with red outline represents the observed lattice parameter and fractiraial coordinate, respectively [71], Contour lines are at 0.29, 0.5, 0.75, and 1 valence units... 

Fig. 17 SPuDS predicted blue diamonds) and observed open red squares) global instability index for A2 B2" 07 pyrochlores...

The predicted structures obtained by optimizing the bond valences of the ions have BVSs close to their formal valences. The degrees of freedom in the spinel structure enable the simultaneous optimization of the BVS for each of the A-, B-, and X-site ions. Within calculation limitations, a zero global instability index (G) is fotmd for each of the predicted structures. The experimentally determined structures have a larger G, ranging from about 0.04 to 0.27 v.u. with an average of 0.15 v.u. for the examined structures. Unlike the cubic perovskite and pyrochlore structure, the spinel is not a strained structure. Regardless of the sizes of the A and B... 

Fig. 10 Influence of b averaging on the global instability index G fm 128 compounds that contain both a chalcogenide and a halide anion. The solid line marks the ratio 1 1, the broken line a fourth order polynomial over all data...

---