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Time parameters techniques

Of course, it is well known that because of the duality of the time and frequency parameters, there is no universal time-frequency technique. Indeed the two parameters cannot be simultaneously known with arbitrarily high resolution. This is expressed by the Heisenberg - Gabor inequality ... [Pg.360]

Knowledge of the dynamics of excited states is of major importance in understanding photophysical, photochemical and photobiological processes. Two time-resolved techniques, pulse fluorometry and phase-modulation fluorometry, are commonly used to recover the lifetimes, or more generally the parameters characterizing the S-pulse response of a fluorescent sample (i.e. the response to an infinitely short pulse of light expressed as the Dirac function S). [Pg.167]

Cell kinetics is defined as the measurement of time parameters m biological systems. Traditionally, this has involved the use of radioactive precursors of DNA, such as tritiated thymidine (3HTdR), and autoradiography to detect their incorporation into DNA. This technique has provided detailed knowledge of cell kinetics in both in vitro and in vivo experimental systems. The technique, however, is time consuming and arduous and is not readily applicable to human tumor research because of ethical problems involved in incorporation of a radioisotope into DNA. [Pg.255]

Several studies directed to the estimation of the relevant parameters that control the kinetics of radical pair combination processes using time-resolved techniques have been reported. Results have been interpreted generally using expressions such as Equations 13.1 or Equation 13.2, as well as more sophisticated theoretical treatments. However, obtaining dependable absolute (or even relative) values of and A (Jab has been a formidable task. [Pg.285]

Finally, there are numerous techniques for signal enhancement such as avidin - biotin - complexes and tyramide signal amplification methods. All of these tertiary procedures obviously add to the time parameter of any test, but can add significant staining intensity that is critical in samples with low numbers of antibody binding sites. Determination of methodology for cell staining must be evaluated on the basis of tissue/cells samples to be examined. [Pg.336]

Unlike the transfer-function-based technique, the time-domain technique does not require the central values of the nominally constant parameters to be determined from a minimization exercise. Nevertheless, we will expect the modeller to use sensible estimates, which may be expressed as a condition similar to inequality (24.52) ... [Pg.321]

Technique Time parameter Usual range of parameter s Time window (s ... [Pg.480]

Figure 8.20. Log-log plot of Xa against time showing technique for estimating values of Avrami parameters n and k,. Figure 8.20. Log-log plot of Xa against time showing technique for estimating values of Avrami parameters n and k,.
Figure 3 Three RF pulse sequences used in combination with MAS. The 90° pulses are black while the 180° pulses are gray (A) SP-MAS (B) PASS (C) the prototype PHORMAT. The various timing parameters are explained in the text. (Reprinted with permission from Hu JZ and Wind RA (2002) The evaluation of different MAS techniques at low spinning rates in aqueous samples and in the presence of magnetic susceptibility gradients. Journal of Magnetic Resonance 159 92-100 Elsevier)... Figure 3 Three RF pulse sequences used in combination with MAS. The 90° pulses are black while the 180° pulses are gray (A) SP-MAS (B) PASS (C) the prototype PHORMAT. The various timing parameters are explained in the text. (Reprinted with permission from Hu JZ and Wind RA (2002) The evaluation of different MAS techniques at low spinning rates in aqueous samples and in the presence of magnetic susceptibility gradients. Journal of Magnetic Resonance 159 92-100 Elsevier)...
In recent times, UPLC technique has routinely been performed for analysis of pharmaceutical formulations natural products foods and herbal medicines in various research institutes laboratories concerned with biochemistry, biotechnology, environmental analysis natural product research and several other research fields. For the analysis of foods, natural products, or medicines, analytical scientist need to extend their understanding to provide evidence-based validation and effectiveness to establish safety parameters for their production. Also, the rapid separation of samples is an analytical stage that requires high efficiency as well as speed due to the complexity of the sample matrix, and hence it is particularly challenging to achieve. UPLC provides high-quality separations and detection capabilities to identify active compounds in highly complex samples that result from natural products and analyzed foods. [Pg.98]

Both linear and nonlinear Raman spectroscopy can be combined with time-resolved detection techniques when pumping with short laser pulses [8.781. Since Raman spectroscopy allows the determination of molecular parameters from measurements of frequencies and populations of vibrational and rotational energy levels, time-resolved techniques give information on energy transfer between vibrational levels or on structural changes of short-lived intermediate species in chemical reactions. One example is the vibrational excitation of molecules in liquids and the collisional energy transfer from the excited vibrational modes into other levels or into translational energy of the collision partners. These processes proceed on picosecond to femtosecond time scales [8.77,8.79]. [Pg.527]

In spite of the steady-state regime during the electrolytic process the adequate time window remains for the estimation of kinetic parameters. Data given in Table 2 indicate that the variation of time parameters is possible in all three techniques involved in this section. [Pg.172]

This section is inspired by the heated debate around the onset of primary crystallization in semiciystalline polymers (30-32,80-85) and the many discussions regarding experimental technique that have taken place because of this debate. Although this example will be used, the underlying idea is that many time-resolved experiments where technique combinations are used are performed to establish the relation between different parameters. This can be the order in which events happen but also differences in the time evolution of the values of parameters. The determination of the simultaneity of two events is typical of combined time-resolved techniques that are becoming more normal in SR experiments. Therefore some details in this specific experiment will be treated in a little more detail as an example of problems that can arise in time-resolved SR experiments. Another experiment where a similar question is addressed can be foimd in the section where spectroscopic techniques (ftir) in combination with saxs are discussed. [Pg.8156]


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See also in sourсe #XX -- [ Pg.552 , Pg.553 ]




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