Molecular specific

The second issue concerns molecular specificity. For a simple measurement of SHG at an arbitrary laser frequency, one caimot expect to extract infomiation of the behaviour of a system with several possible adsorbed species. To make the technique appropriate for such cases, one needs to rely on spectroscopic infomiation. In the simplest iiiiplementation, one chooses a frequency for which the nonlinear response of tlie species of interest is large or dominant. As will... 

Such approximation is valid when the thickness of the polymeric layer is small compared to die thickness of die crystal, and the measured frequency change is small with respect to the resonant frequency of the unloaded crystal. Mass changes up to 0.05% of die crystal mass commonly meet this approximation. In die absence of molecular specificity, EQCM cannot be used for molecular-level characterization of surfaces. Electrochemical quartz crystal microbalance devices also hold promise for the task of affinity-based chemical sensing, as they allow simultaneous measurements of both tile mass and die current. The principles and capabilities of EQCM have been reviewed (67,68). The combination of EQCM widi scanning electrochemical microscopy has also been reported recently for studying die dissolution and etching of various thin films (69). The recent development of a multichannel quartz crystal microbalance (70), based on arrays of resonators, should further enhance die scope and power of EQCM. 

The Volta potential is defined as the difference between the electrostatic outer potentials of two condensed phases in equilibrium. The measurement of this and related quantities is performed using a system of voltaic cells. This technique, which in some applications is called the surface potential method, is one of the oldest but still frequently used experimental methods for studying phenomena at electrified solid and hquid surfaces and interfaces. The difficulty with the method, which in fact is common to most electrochemical methods, is lack of molecular specificity. However, combined with modem surface-sensitive methods such as spectroscopy, it can provide important physicochemical information. Even without such complementary molecular information, the voltaic cell method is still the source of much basic electrochemical data. 

As stressed in the introduction, the main difficulty ofthe voltaic cell method of investigating systems is its lack of molecular specificity. Therefore, complementary information should be obtained by using techniques sensitive to the polar ordering and arrangement of molecules in a surface or interfacial layer, such as optical, spectroscopic, and scanning tunneling microscope methods. " ... 

Element-specific detection Molecular-specific detection... 

Both the identification of a species and the determination of the kinetics of its formation or decay can be achieved with longer pathlength cells, such as that depicted in Figure 2.103. In kinetic experiments, however, there is the proviso that the experiment can be performed before natural convection currents interfere with the measurements i.e. the operator must be certain that the removal of a chromophore from the optical path is due to reaction and not due to convection currents. It should be noted that the strength of UV-visible spectroscopy does not lie primarily in the identification of unknown species as the information it provides is not of a molecularly specific nature. 

Vasudevan N, Ogawa S, Pfaff D (2002) Estrogen and thyroid hormone receptor interactions physiological flexibility by molecular specificity. Physiol Rev 82 923... 

Although the evolutionary trace method applied to GPCRs (175,185) fails to detect any residues responsible for the subtype-specific heterodimerizafion that has recently been demonstrated for opioid (96), somatostatin (106), and chemokine (98) receptors, correlated mutation analysis had already been demonstrated to be able to identify useful details of molecular specificity (184). Thus, the molecular basis of specificity was hypothesized to reside in outward (i.e., lipid) facing residues of TM5 and TM6 that exhibited evolutionarily correlated mutations and differed between receptor subtypes (184) in the case of dimerization. In the case of oligomers, the key interface between different subtypes was suggested to be the 2,3-interface (152) rather than the 5,6-interface. 

Although use of the second harmonic signal from metal surfaces as an indirect probe of chemisorption lacks structural specificity, the utility of the technique is clearly demonstrated by the experiments reported here. The next step in our studies will be to demonstrate how one can directly monitor chemisorption with some degree of molecular specificity via the resonant second harmonic signal from the nonlinear susceptibility of adsorbed species. 

Caprioli, R.M. Analysis of Biochemical Reactions With Molecular Specificity Using FAB-MS. Biochemistry 1988, 27, 513-521. 

NMR is the most fundamental molecular specific probe of diffusion. Polymer motions and the spectroscopic signature of a given nucleus can be unambiguously related to a particular morphological domain. The size and time scale of the experiments are such that the fundamental hopping events of diffusing molecules can be sampled. 

U se of a known low-toxicity scaffold (drug) for building molecular specificity was the most important advance, permitting us to overcome toxicity issues due to the large doses required to treat almost a pound and a half of the in vivo receptor (hemoglobin). When in doubt as to which molecule to forward as a clinical candidate, consider metabolism and toxicity profiles as well as biological activity. 

The metaiioporphyrins form a diverse class of molecules exhibiting complex and varied photochemistries. Until recently time-resolved absorption and fluorescence spectroscopies were the only methods used to study metailoporphyrln excited state relaxation in a submicrosecond regime. In this paper we present the first picosecond time-resolved resonance Raman spectra of excited state metaiioporphyrins outside of a protein matrix. The inherent molecular specificity of resonance Raman scattering provides for a direct probe of bond strengths, geometries, and ligation states of photoexcited metaiioporphyrins. 

Efficient cross-link formation by a small number of wall polymer-bound phenolics requires great precision in the metabolic reactions involved. It is not sufficient to form cross-links the cross-links need to be formed in the proper place within the polymer molecule and within the cell wall. Evidence that cross-links form at all [albeit sometimes as a low percentage of the total wall phenolics] is presented elsewhere (1,2,13,16,30-32). Here we present evidence that sufficient molecular specificity exists to be compatible with useful cross-link formation. 

Steffens, J.C. et al., Molecular specificity of haustorial induction in Agalinis purpurea (L.) Raf. 

Flash and Flame. When Lead Azide was shot in a non-expl atmosphere, an intense luminosity was produced. This light emission was greatest in gas of low molecular specific heat, where the latter does not increase with temperature. The luminosity decreases the greater the specific heat and die temperature coefficient. The following gases were examined and found to have this decreasing order of luminosity ... 

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