Soaking phase

The overall process can be divided into three phases, the heating and cracking phase, the reaction phase, and the soaking phase. 

The soaking phase takes place in the rest of the reactor where the gas is at high temperatures. A portion of the carbon disappears by reactions with CO2 and steam. Some carbon, about 1—3 wt % of the oil feed, is present in the product gas. Natural gas feedstock produces only about 0.02 wt % of carbon. 

C. Soaking Phase. The soaking phase takes place in the rest of the reactor, where the gas is at high temperature. Minor changes in gas composition occur due to secondary reactions of methane and carbon. As the reaction rates are relatively low, the methane content is higher than would be expected from equilibrium. During the soaking phase, a portion of the carbon also disappears by reactions with CO2 and steam. However, some carbon is always present in the product gas from the reactor in a quantity equivalent to about 1-3% wt of the oil feed. Natural gas feedstock produces only a very small amount of residual carbon i.e., about 0.02% wt of the gas feedstock. 

Well-bore scale is not a problem in cyclic COj EOR treatments, except in situations where the soak phase becomes extended enough to allow the COj to equilibrate with minerals in the reservoir. 

Leather industry uses proteolytic and lipolytic enzymes in leather processing. The use of these enzymes is associated with the structure of animal skin as a raw material. Enzymes are used to remove unwanted parts. Alkaline proteases are added in the soaking phase. This improves water uptake by the dry skins, removal and degradation of protein, dirt, and fats and reduces the processing time. In some cases, pancreatic trypsin is also used in this phase. 

Eig. 2. Cychc steam stimulation of an oil well (a) steam, injected into a well over a period of days or weeks in a heavy oil reservoir, introduces heat (huff) that, coupled with (b), alternate soak periods lasting a few days to allow (c) a production phase of weeks or months (puff), thins the oil. This process may... 

In the case of thin-layer chromatography there is frequently no wait to establish complete equilibrium in the chamber before starting the development. The chamber is usually lined with a U-shaped piece of filter paper and tipped to each side after adding the mobile phase so that the filter paper is soaked with mobile phase and adheres to the wall of the chamber. As time goes on the mobile phase evaporates from the paper and would eventually saturate the inside of the chamber. 

Together with this solvent effect, another effect, called phase soaking, occurs in the retention gap technique if a large volume of solvent vapour has saturated the carrier gas, the properties of the stationary phase can be altered by swelling (thicker apparent film), a change in the viscosity or changed polarity. The consequence is that the column shows an increased retention power, which can be used to better retain the most volatile components. 

The same concepts apply to column chromatography, where the stationary phase is normally small particles of silica, Si02, or alumina, A1,0 . These substances are not very reactive and have specially prepared surfaces to increase their adsorption ability. The column is saturated with solvent, and a small volume of solution containing the solutes is poured onto the top. As soon as it has soaked in, more solvent is added. The solutes travel slowly down the column and are eluted (removed as fractions) at the bottom (Fig. 2). If the mobile phase is less polar than the stationary phase, the less polar solutes will be eluted first and the more polar ones last. 

Multiple isomorphous replacement allows the ab initio determination of the phases for a new protein structure. Diffraction data are collected for crystals soaked with different heavy atoms. The scattering from these atoms dominates the diffraction pattern, and a direct calculation of the relative position of the heavy atoms is possible by a direct method known as the Patterson synthesis. If a number of heavy atom derivatives are available, and... 

Platinum was added to Nation before Incorporating CdS In order to avoid the reduction of CdS during the platlnlzatlon process. Nation (DuPont 117, 0.018 cm thick) films were soaked In Pt(NH2)2l2 (0.1 mM) solution for 4 hr. The amount of the Pt complex Incorporated was determined by measuring the optical absorption change In the liquid phase. The films were subsequently reduced with NaBH (0.1 M) solution for one day to produce Pt metal dispersed throughout the polymer film. The amount of Pt was found to be about 0.02 mg cm 2. 

Chamber saturation is recommended for better reproducibility of the separation — especially if multicomponent mobile phase mixtures are composed of solvents differing in volatility or polarity to a great extent. Moreover, chamber saturation can improve resolution of two components or reduce the formation of secondary fronts. For chamber saturation, the large tank sides are lined with a sheet of filter paper 20 X 20 cm each. Dnring the filling of the mobile phase into the chamber, it is poured onto the filter, which is then completely wetted and soaked by the mobile phase. Note that the wet filter paper is dipped into the mobile phase at the trough bottom. The prepared closed tank will become satnrated within 15 to 30 min depending on the volatihty of the solvent components (withont wetted filter paper it needs more... 

Once a suitable crystal is obtained and the X-ray diffraction data are collected, the calculation of the electron density map from the data has to overcome a hurdle inherent to X-ray analysis. The X-rays scattered by the electrons in the protein crystal are defined by their amplitudes and phases, but only the amplitude can be calculated from the intensity of the diffraction spot. Different methods have been developed in order to obtain the phase information. Two approaches, commonly applied in protein crystallography, should be mentioned here. In case the structure of a homologous protein or of a major component in a protein complex is already known, the phases can be obtained by molecular replacement. The other possibility requires further experimentation, since crystals and diffraction data of heavy atom derivatives of the native crystals are also needed. Heavy atoms may be introduced by covalent attachment to cystein residues of the protein prior to crystallization, by soaking of heavy metal salts into the crystal, or by incorporation of heavy atoms in amino acids (e.g., Se-methionine) prior to bacterial synthesis of the recombinant protein. Determination of the phases corresponding to the strongly scattering heavy atoms allows successive determination of all phases. This method is called isomorphous replacement. 

Fig. 16. Effect of soaking TS-1 with water on the XANES (a) and UV-Raman (b) spectra dried TS-1 (solid line) soaked TS-1 (dotted line). The inset in part (a) reports the U-weighted, phase-uncorrected Fourier transforms of the corresponding EXAFS spectrum [Reprinted from Ricchiardi et al. (41) with permission. Copyright (2001) American Chemical Society].

When the LB film-deposited QCM was lowered and raised through the air-water interface at 20 °C, the frequency of the QCM was observed to increase (the mass decrease) compared with that before soaking into the water phase. This is due to the detachment of LB films from the QCM substrate during dipping processes. Figure 17 shows the typical frequency increase (mass decrease) of the QCM deposited with cadmium octadecanoate LB films (10 layers on each side of the QCM, 1130 5 ng), when the QCM substrate was lowered and raised repeatedly through the interface at a rate of 100 mm min. Any increase in surface pressure wasn t observed during the experiments. The frequency of the QCM was... 

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