Residual impression parameter

Let us analyse the above data on the basis of Lawn and Howes analysis 29). Based on the mechanics of hardness identation - assuming the loading cycle to be elastic-plastic and unloading to be elastic — these authors have recently derived an interesting expression of the residual impression parameter (relative depth recovery) as function of the ratio MH/E. Accordingly ... 

Impression depth after unloading divided by the unrecovered depth L is called the residual impression parameter, and this parameter squared is related to hardness and Young s modulus from equations (6.10), (6.11),... 

It is not always possible to measure the indent depth directly by focussing on indent bottom and surface, respectively, at the depths required to produce uncracked indentation, but when it is done equation (6.12) is found to be obeyed with respect to a linear dependence between Hy/E and residual impression parameter squared until low values of Hy/E are encountered. 

Yield and absolute hardness, 72 Y-sialon glass density, 229 Knoop hardness, 229 Modulus, 229 Young s modulus of AljOj, 241, 259-261 anisotropy in /3-AI2O3, 281 of B4C, 228, 241 and bond type, 172 and crack depth, 155 and cracking, 147 of CrjCj, 302 of germanium, 252 of glass, 238 and hardness, 72 hardness ratio, 179 from Knoop indents, 180 mismatch stress, 273 of MgO, 241, 269 and penetration depth, 47, 240 and plasticity parameter, 241 and residual impression parameter, 240... 

Fig. 5a,b Schematic representation of a the tip-sample contact upon high loading b the according compliance curve. In the case of perfectly plastic response the unloading curve is identical to the vertical line intersecting with the abscissa at hmax. In general, some viscoelastic recovery occurs and the residual impression depth hy is smaller than hmax. The difference hc—hy represents the extent of viscoelastic recovery. Ap and Ae denote the dissipated and the recovered work, respectively. Ap=0 for perfect elastic behaviour, whereas Ae=0 for perfect plastic behaviour. The viscoelastic-plastic properties of the material may be described by the parameter Ap(Ap+Ae) l. The contact strain increases with the attack angle 6. Adapted from [138]... 

Using these equations with the known indenter parameters ( , v, and i ,) and measured radius of residual impression R, the elastic modulus of the material E can be determined. The hardness H can also be quantified by... 

The sensitivity achieved (LOD) is not normally presented. It is recognized that different laboratories determine dissimilar values for this parameter and even within a laboratory the repeatability of the LOD is low. Most often, the lowest validated concentration gives an impression about the lowest levels that can be analyzed generally with acceptable results. A measure of selectivity is the intensity of blank results. This intensity is discussed by the participants of inter-laboratory validation studies. However, results are not reported and limits are not defined by CEN TC 275. The results of method validations of the several multi-residue/multi-matrix methods are not reported in the same way, but newer methods with limited scope generate analogous tables with validation results (as an example, see Table 7). 

While this example of the Robinson annulation is clearly not enantioselec-tive, the same antibody converts the mero-ketone [120] into the Wieland-Miescher (WM) decalenedione product kcM = 0.086 min-1 and Km = 2.34 mM at 25°C, parameters that give an impressive ER of 3.6 x 106. Good evidence suggests that the mechanism of the reaction involves the formation of a ketimine with the e-amino group of a buried lysine residue in the antibody, as shown in Fig. 39. Most significantly, the reaction delivers the ( )-(+)-WM product in 96% ee (by polarimetry) and in 95% ee by nmr and hplc analysis for a 100 mg scale reaction. A recent report tells that this antibody is to be made commercially available at a cost of 100 for 10 mg. The realization of that objective would mark the start of a new era of application of abzymes to organic stereoselective synthesis. 

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