Cycling experiment

The impact of the diffusion coefficient was also analysed here values of isoprene and oxygen were taken [85], It was found that the RTD of one component in a cycling experiment may be narrow, while the other component is not at optimum. By changing the channel diameter, such a sequence may even be reversed. It is advised [85] to operate in the diffusion-dominated branch rather than in the convection-dominated branch. 

A temperature cycling experiment comprising three cycles of —70/50°C with CD and UV spectra recorded at each temperature for 56 indicated that the transition is reversible, with negative and positive Cotton effects being observed at the low and high temperatures, respectively, as is evident in Figure 4.44. 

Cant, Trimm, and coworkers—influence of H20 on oxidation/reduction rates during cycling with 02 and H2 and evidence for reoxidation by H20. Padeste et al.367 reported on the influence of H20 on the reduction/oxidation of ceria during cycling with 02 and H2, and they utilized TPR, XPS, and cycling experiments to... 

For spin-f nuclei, dipolar interactions may be modulated by intramolecular (DF, reorientation etc.) and/or intermolecular (TD) processes. In general, the intra- and inter-molecular processes can produce quite different Tj frequency dispersion curves. In practice, NMR field cycling experiments are often needed to extend the frequency domain from those employed in conventional spectrometers to a lower frequency range (i.e., the kHz regime) for unambiguous separation (and identification) of different relaxation mechanisms. The proton spin relaxation by anisotropic TD in various mesophases has been considered by Zumer and Vilfan.131 133,159 In the nematic phase, Zumer and Vilfan found the following expression for T ... 

Fig. 2. The different stages of a field-cycling experiment. Spins are pre-polarized in a relatively high static magnetic field (Bq). The relevant magnetization then decays to its equilibrium value in the field Bq according to the longitudinal relaxation time of interest (at a frequency equal to yBQl2n). For sensitivity reasons, magnetization is read again in the Bq field (a n/2 pulse yielding an fid Acq).

A field-cycling experiment requires that the sample be subject at different times, and for variable durations, to different values of the magnetic field B. From the instrumental point of view, there are basically just two ways to achieve this goal. 

The origin of the deep localized states in the mobility gap that control the dark decay has been attributed to structural native thermodynamic defects [12]. Thermal cycling experiments show that the response of the depletion time to temperature steps is retarded, as would be expected when the structure relaxes toward its metastable liquid-like equilibrium state. As the structure relaxes toward the equilibrium state, t(j decreases further until the structure has reached equilibrium. The only possible inference is that must be controlled by structure-related thermodynamic defects. The generation of such defects is, therefore, thermally activated. We should note that because the depletion discharge mechanism involves the thermal emission of carriers... 

Pusz J., Smirnova A., Mohammadi A. and Sammes N.M., 2007. Fracture strength of microtubular solid oxide fuel cell anode in redox cycling experiments. Journal of Power Sources 163(2), 900-906. 

N diffuses into the structural pores of clinoptilolite 10 to 10 times faster than does CH4. Thus internal surfaces are kinetically selective for adsorption. Some clino samples are more effective at N2/CH4 separation than others and this property was correlated with the zeolite surface cation population. An incompletely exchanged clino containing doubly charged cations appears to be the most selective for N2. Using a computer-controlled pressure swing adsorption apparatus, several process variables were studied in multiple cycle experiments. These included feed composition and rates, and adsorber temperature, pressure and regeneration conditions. N2 diffusive flux reverses after about 60 seconds, but CH4 adsorption continues. This causes a decay in the observed N2/CH4 separation. Therefore, optimum process conditions include rapid adsorber pressurization and short adsorption/desorp-tion/regeneration cycles. 

The recommended dosage of clomiphene citrate at the beginning of therapy is 50 mg/d for 5 days. If ovulation occurs, this same course may be repeated until pregnancy is achieved. If ovulation does not occur, the dosage is doubled to 100 mg/d for 5 days. If ovulation and menses occur, the next course can be started on the fifth day of the cycle. Experience to date suggests that patients who do not ovulate after three courses of 100 mg/d of clomiphene are not likely to respond to continued therapy. However, larger doses are effective in some individuals. Clomiphene is sometimes used in combination with gonadotropins, ie, a combination of LH and FSH. 

Forced Composition Cycling Experiments in a Fixed-Bed Ammonia Synthesis Reactor... 

This pathway is permitted in the phase cycled experiment, but the data from this pathway is lost in the gradient version. In this sense, gradients are sometimes too selective because they generally allow only one coherence level even when two or more pathways are equivalent in terms of the signal we want to see. 

Because methanol is not actually a solvent for PVA, some interesting sorption/desorption cycling experiments can be conveniently run on PVA films without disrupting the film integrity. As noted above, methanol produces a slow increase of shear stiffness (Adh) when layered on PVA. The time scale and curve shape are suggestive of a diffusion process (liquid into polymer). By removing the liquid layer, we should permit methanol to evaporate from the film and thus reverse the effect. The... 

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