Discrimination factor

It is important to consider the discrimination factor. People with dark skin may fail the urine test due to the false positive melanin. Drugs are detected easier in dark haired people when the hair test is used [Berns]. 

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Comar, C.L., Wasserman, R.H. and Nold, M.M. 1956 Strontium-calcium discrimination factors in the rat. Proceedings of the Society for Experimental Biology 92 859-863. 

Discrimination factors on different trophic levels in relation to the trace element content... 

The constant s, characteristic of the substrate complex, reflects its sensitivity to variation in nucleophilicity as assessed by the Ptpy2Cl2 reaction. It is called the nucleophilic discrimination factor (ndf). The intercept log k turns out to be related to the value of the k term in the rate law for the solvent in question. Some representative ligands involved in attack on Pt(II) complexes may be listed in order of decreasing as follows ... 

In the transport across a phospholipid bilayer by passive diffusion, the permeability of the neutral form of a molecule is 10X times greater than that of the charged form. For the epithelium, the discrimination factor is 105. The basement membrane (Fig. 2.5) allows passage of uncharged molecules more readily than charged species by a factor of 10 [76]. 

El Fallah, M.Z., Martin, M. (1987). Influence of the peak height distribution on separation performances discrimination factor and effective peak capacity. Chromatographia 24, 115. 

It is clear that above 15 kcal/mol, a region of saturation of the first-order electrostatic effect is entered, and a second-order effect can be discerned becoming the discriminating factor of hydrogen bond strength. 

The relevant AGB values, calculated by using Te = 970 are listed in Table 8. According to the reported values, the heterochiral Trp/Pro and Phe/Ala complexes are more stable than the homochiral ones. The reverse is true for the Phe/ Pro and PheA al complexes. By the same token, the chiral discrimination factor, AR measured by ESl-MS for 19 amino acids was found to vary between 0.3 and 3. ° The stereochemistry associated to the CID of diastereomeric peptides has been investigated using a similar approach. The results suggest that the secondary structure of protonated peptides may play an important role in their gas-phase behavior. ... 

It is also clear (e.g. from the inactive 4 position in quinoline) that there is in general no more justification for using 7Tr, by itself than for using g, it is only for alternant hydrocarbons that the self-polarizability is the discriminating factor, and in all other cases tt,, should be considered only to the extent that it modifies conclusions based on the leading term g Sa,. in (18). Moreover, the relative importance of the two terms depends on the value of 8[Pg.87]

On the basis of this equation, an index of nucleophilicity pt can be assigned to each nucleophile Y (see Table 4.13). It is found, moreover, that a plot against pt of logfcy, for reaction of Y with another Pt(II) neutral substrate, is also often linear. Thus, Eq. (2.168) applies, and 5 is termed the nucleophilic discrimination factor (Sec. 4.7.1). Some of the departures from linearity of plots of Ary vs p, which have been observed, disappear if the Pt reference substrate chosen is of the same charge as the Pt reactants. The value of p, for a bulky nucleophile has also to be modified to allow for steric hindrance features. 

All the kinetic features expected for a D mechanism and rate law (4.9) i. e. marked effects of L and Lj on the rate constants, are shown in the comprehensive studies in nonaqueous solution of substitution in low-spin Fe(II) complexes of the type FeN4XY where N4 are planar porphyrins, phthalocyanins and macrocycles and X and Y are neutral ligands, CO, R3P, pyridines etc. Small discrimination factors (Ar, /kj) suggest that the five-coordinated intermediate in these systems is very reactive.There have been problems in the confirmation of curvature in the plots of A o,j/[L ] for classical reactions of a number of aquapent-ammine complexes. ... 

The term s is the nucleophile discrimination factor. The values of pt, the nucleophilic reactivity constant, is useful for correlating kinetic data for other Pt(II) complexes. 

Panic Disorder. Panic attacks are commonly experienced by patients with PTSD. In addition, the avoidant symptoms of PTSD resemble agoraphobia, and the hyperarousal symptoms of PTSD bear some semblance to certain panic symptoms. The key discriminating factor is that patients with panic disorder will, at some point in the course of the illness, experience spontaneous panic attacks arising in the absence of any traumatic reminder or other precipitating stressor. 

However, with compounds such as nitroveratrole, where the lifetime is excluded as a discriminating factor between the meta- and pora-position, the results indeed indicate a higher reactivity at the meta-position (Stratenus, 1966). These systems at the same time furnish nice examples of a complementarity between the reactions in the ground state (ortAo-para-activation) and in the excited state (meta-activation with respect to the nitro-group). The conception of... 

This approach discriminates factors to a large extent in order to distinguish between the single adjustments and to separate best estimates from uncertainty. It should be noted that the ECETOC approach does not mention the establishment of an overall factor and although they mention that all discriminated aspects introduce uncertainties, they do not give guidance on how to account for this. It could also be questioned here whether a nonscientific factor should be discussed in a scientific risk assessment. 

In the acid hydrolysis of the pentamminecobalt complexes where you have a leaving group, such as nitrato or bromo, H. Taube and A. Haim came out with some very interesting work, with which I am sure you are all familiar. They suggested that the five-coordinated pentamminecobalt species was formed which then discriminated between various nucleophilic reagents, sometimes reacting with water, sometimes with- thiocyanate ion. In fact, they were able to measure these nucleophilic discrimination factors in a number of cases, and they were able to correlate different types of reactions in which the pentamminecobalt would be generated in different ways. 

The structure determination confirmed the importance of the spacing of the two hexamers as a discrimination factor in an impressive maimer. A spacing of only 3 nucleotides between the two hexamers would lead to steric overlap of both receptors a high affinity, cooperative binding would not be possible. With a spacing of more than 4 nucleotides a high affinity complex could also not be formed due to the relative rigidity of the two monomers. 

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