Amplification effects

Conventional ion-selective electrodes have been used as detectors for immunoassays. Antibody binding measurements can be made with hapten-selective electrodes such as the trimethylphenylammonium ion electrode Enzyme immunoassays in which the enzyme label catalyzes the production of a product that is detected by an ion-selective or gas-sensing electrode take advantage of the amplification effect of enzyme catalysis in order to reach lower detection limits. Systems for hepatitis B surface antigen and estradiol use horseradish peroxidase as the enzyme label and... 

By constrast, the methylzinc complexes bearing the sterically more encumbered anisyl fencholates with tert-butyl and trimethylsilyl substituents dimerized preferentially in the heterochiral form, resulting in the more common chiral amplification effects observed for classical dimethylaminoisoborneol systems. 

Acid diffusion. Acid catalyzed resist systems are particarly noteworthy for their high sensitivity toward radiation. However it has been suggested that the amplification effect observed with catalytic resist systems is achieved only at the expense of lost resolution. Some diffusion of catalyst is necessary to achieve sufficient loss of BOC groups in order to impart sufficient difference in polarity for discriminatory film dissolution. Yet unlimited acid diffusion would result in loss of resolution. 

The authors also investigated the mode of activation of these BINOL-derived catalysts. They proposed an oligomeric structure, in which one Ln-BINOL moiety acts as a Brpnsted base, that deprotonates the hydroperoxide and the other moiety acts as Lewis acid, which activates the enone and controls its orientation towards the oxidant . This model explains the observed chiral amplification effect, that is the ee of the epoxide product exceeds the ee of the catalyst. The stereoselective synthesis of cw-epoxyketones from acyclic cw-enones is difficult due to the tendency of the cw-enones to isomerize to the more stable fraw5-derivatives during the oxidation. In 1998, Shibasaki and coworkers reported that the ytterbium-(f )-3-hydroxymethyl-BINOL system also showed catalytic activity for the oxidation of aliphatic (Z)-enones 129 to cw-epoxides 130 with good yields... 

For a large number of materials, the stability condition, Eq. (8.26), is satisfied. In addition, in most cases, the STM images are taken under attractive-force conditions. The dramatic amplification effect does not occur. However, the effect of force and deformation is still observable. By measuring the apparent barrier height using ac method, based on Eq. (1.13),... 

In this connection, Fig. 2 provides a qualitative illustration for interpreting modulus change of an elastomer upon filler blending 9). A hydrodynamic or strain amplification effect, the existence of filler-elastomer bonds, and the structure of carbon black 10) all play a part in this modulus increase. 

It follows that this strain amplification effect will be more important if a high structure carbon black is used. In this case, indeed, the real volume concentration of the filler will be significantly increased by the amount of occluded rubber trapped in the aggregates. At strains high enough, the occluded rubber, though anchored or... 

Metal-based receptors which are able to form preorganised monolayers on planar electrodes can be expected to do the same on the surface of nanoparticles, leading to a surface sensing amplification effect. The very large surface area of nanoparticles could also allow greater overall sensitivity to anions. 

The presence of N-atoms in the aromatic part of the aldehyde appears essential for chiral amplification. With only one nitrogen, such as in the case of 3-pyridine carbaldehyde, autocatalytic kinetics but no chiral amplification effect has been observed [24,25]. In the case of 3-quinoline carbaldehyde, i.e., in the presence of two nucleophilic centers, autocatalysis as well as moderate chiral amplification were reported [26,27]. Highest amplification capacity is observed in the presence of two N-atoms in the aromatic part of the aldehyde, where for the substituent at the 2-position the amplification capacity increases H < CH3 < f- Bu - C=C -, i.e., with the size and rigidity of this group. So far, detailed studies that could relate the given observations to the possible mechanism of chiral amplification in Soai s reaction are still to be carried out. 

According to Soai and coworkers [31], the strong chiral amplification sometimes observed in their system cannot be explained by so-called NLE alone since amplification effects in these cases remain at a more moderate level. Hence a more complex reaction mechanism than expressed by the reservoir or the ML model is indicated for the Soai reaction. 

Abstract These notes present the physics of gravitational lensing in various cosmological contexts. The equations and approximations that are commonly used to describe the displacement field or the amplification effects are presented. Several observational applications are discussed. They range from micro-lensing effects to cosmic shear detection that is a weak lensing effect induced by the large-scale structure of the Universe. The scientific perspectives of this latter application are presented in some details. 

The detection of gravitational effects due to stars should then be done by another mean the amplification effect. 

The amplification effect for each image is given by the inverse of the determinant of the amplification matrix computed at the apparent position of the image. The amplification factor is usually noted //. 

Sharpless asymmetric epoxidation of allylic alcohols, asymmetric epoxidation of conjugated ketones, asymmetric sulfoxidations catalyzed, or mediated, by chiral titanium complexes, and allylic oxidations are the main classes of oxidation where asymmetric amplification effects have been discovered. The various references are listed in Table 4 with the maximum amplification index observed. 

One further point is worth bearing in mind. The precision in the measurement of translational energies of ions formed in a source is generally much less than that in analogous measurements on metastable ions (Sect. 3.2.3). This is because the amplification effect (Sect. 3.2.3) on moving from centre-of-mass to laboratory framework is insignificant with decompositions in a source because the reactant ions are moving relatively slowly. The laboratory distributions measured for source reactions often span less than leV, whereas those for metastable ions may span tens of electron volts and more. 

MS. The amplification effect is exemplified by the preparation of ATP synthase, in which the spectrum without microchip preparation results in a few unidentifiable peaks around the molecular weight of 850 (see Figure 14, left spectrum). The rest of the spectrum does not show any peaks above the noise level. With microchip preparation we can identify seven peptide masses that corresponds to the successful identity of ATP synthase (see Figure 14, right spectrum). The low level of expression of this protease is also seen from the weak but fully isotope resolved peptides in the spectrum. 

Amplification expressions in general are not as simple as equation (51) for two-phase flows in rocket motors [128]. Equilibrium and frozen sound speeds with respect to droplet behavior may be identified (compare Sections 9.1.4.6 and 4.2.6), and a mass-source term may arise in equation (51) in the development of a conservation equation for the acoustic energy in the gas. From the viewpoint of equation (14), the quantity O must include amplification effects that arise from both energy sources and mass sources. Acoustic theories may be derived from the conservation equations of Chapter 11 for the purpose of analyzing acoustic amplification in spray combustion. 

Because of the square dependence of the relaxation rate on the electric field gradient tensor invariant minor alterations of valence electron symmetry may give rise to sizeable relaxation differentials. Thanks to this amplification effect the binding of ions can be studied at low substrate concentration provided that the resulting complex is kinetically labile. The relaxation rate thus emerges as a complementary experimental observable, at least as informative as the chemical shift. 

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