Transient liquid phase method

Butt DP, Cutler RA, Rynders SW, Carolan MF. Method of joining ion transport membrane materials using partially or fully transient liquid phase. U.S. Patent 7,011,898, 2006. 

Gal-Or and Hoelscher (G5) have recently developed a fast and simple transient-response method for the measurement of concentration and volumetric mass-transfer coefficients in gas-liquid dispersions. The method involves the use of a transient response to a step change in the composition of the feed gas. The resulting change in the composition of the liquid phase of the dispersion is measured by means of a Clark electrode, which permits the rapid and accurate analysis of oxygen or carbon dioxide concentrations in a gas, in blood, or in any liquid mixture. 

Measurements Using Liquid-Phase Reactions. Liquid-phase reactions, and the oxidation of sodium sulfite to sodium sulfate in particular, are sometimes used to determine kiAi. As for the transient method, the system is batch with respect to the liquid phase. Pure oxygen is sparged into the vessel. A pseudo-steady-state results. There is no gas outlet, and the inlet flow rate is adjusted so that the vessel pressure remains constant. Under these circumstances, the inlet flow rate equals the mass transfer rate. Equations (11.5) and (11.12) are combined to give a particularly simple result ... 

A further method of producing amorphous phases is by a strain-driven solid-state reaction (Blatter and von Allmen 1985, 1988, Blatter et al. 1987, Gfeller et al. 1988). It appears that solid solutions of some transition metal-(Ti,Nb) binary systems, which are only stable at high temperatures, can be made amorphous. This is done by first quenching an alloy to retain the high-temperature solid solution. The alloy is then annealed at low temperatures where the amorphous phase appears transiently during the decomposition of the metastable crystalline phase. The effect was explained by the stabilisation of the liquid phase due to the liquid—>glass... 

The development of mass spectrometric ionization methods at atmospheric pressures (API), such as the atmospheric pressure chemical ionization (APCI)99 and the electrospray ionization mass spectrometry (ESI-MS)100 has made it possible to study liquid-phase solutions by mass spectrometry. Electrospray ionization mass spectrometry coupled to a micro-reactor was used to investigate radical cation chain reaction is solution101. The tris (p-bromophenyl)aminium hexachloro antimonate mediated [2 + 2] cycloaddition of trans-anethole to give l,2-bis(4-methoxyphenyl)-3,4-dimethylcyclobutane was investigated and the transient intermediates 9 + and 10 + were detected and characterized directly in the reacting solution. However, steady state conditions are necessary for the detection of reactive intermediates and therefore it is crucial that the reaction must not be complete at the moment of electrospray ionization to be able to detect the intermediates. 

Fig. 4. Energy below the conduction band of levels reported in the literature for GaP. States are arranged from top to bottom chronologically, then by author. At the left is an indication of the method of sample growth or preparation liquid phase epitaxy (LPE), liquid encapsulated Czochralski (LEC), irradiated with 1-MeV electrons (1-MeV e), and vapor phase epitaxy (VPE). Next to this the experimental method is listed photoluminescence (PL), photoluminescence decay time (PLD), junction photocurrent (PCUR), photocapacitance (PCAP), transient capacitance (TCAP), thermally stimulated current (TSC), transient junction dark current (TC), deep level transient spectroscopy (DLTS), photoconductivity (PC), and optical absorption (OA).

The methods for both semi-batch and continuous reactors are generally restricted to the 02-aqueous system because of the limitations of the analytical technique for the direct measurement of liquid-phase concentration. Novel agitated vessels for measurement of transient absorption rates are described by Danckwerts and Kennedy (1954), Oishi et al. (1965) and Govindam and Quinn (1964). 

In a third paper by the Bernard and Holm group, visual studies (in a sand-packed capillary tube, 0.25 mm in diameter) and gas tracer measurements were also used to elucidate flow mechanisms ( ). Bubbles were observed to break into smaller bubbles at the exits of constrictions between sand grains (see Capillary Snap-Off, below), and bubbles tended to coalesce in pore spaces as they entered constrictions (see Coalescence, below). It was concluded that liquid moved through the film network between bubbles, that gas moved by a dynamic process of the breakage and formation of films (lamellae) between bubbles, that there were no continuous gas path, and that flow rates were a function of the number and strength of the aqueous films between the bubbles. As in the previous studies (it is important to note), flow measurements were made at low pressures with a steady-state method. Thus, the dispersions studied were true foams (dispersions of a gaseous phase in a liquid phase), and the experimental technique avoided long-lived transient effects, which are produced by nonsteady-state flow and are extremely difficult to interpret. 

The presence of H2O2 and salt in the liquid phase generally elevates the associated lu values above those obtained by the transient method. A slight modification of this steady-state method allows the authors to use ferric chloride instead of bovine catalase in large-scale experiments. 

Basara et al [3] simulated single- and two-phase turbulent flows in stirred vessels equipped with six- and four blade Rushton-t3q)e turbines using the sliding mesh impeller method. To describe turbulence in the liquid phase a standard k-e model was used for single phase calculations and an extended k-e model was employed for the two-phase simulations. These simulations were performed in transient mode with 1 (ms) time steps. The whole calculation contains 3900 time steps, which means approximately 4s of real time and 17 complete rotations of the impeller. One such simulation took 13 days of CPU time using an Intel single processor with 2.6 GHz). The flow patter predictions were compared with experimental data and fair agreement was obtained. It was stated that the standard k-e model over-predicted the... 

The liquid phase equations determine the droplet temperature T r, t) and also the volumetric fraction 4>- r, t) during the transient droplet heating. Then and are used to solve the gas phase equations. Note that the boundary and initial conditions, (40.19)-(40.22) and also (40.26) show how the liquid-phase equations are coupled with the gas-phase equations, and therefore, an iterative method has to be employed to solve the equations. 

The nonstationary (transient) operation of chemical reactors is traditionally applied in kinetic research in order to reveal reaction mechanisms. Pulses and step changes can be introduced in continuous reactors, and concentration changes at the reactor outlet are monitored by on-line or off-line analysis. The method is applicable to both gas- and liquid-phase systems. Isotope exchange can be commenced wherein H2/D2 (hydrogen/deuterium) experiments can reveal the role of hydrogen in a catalytic process. Some examples of catalytic isomerizations are displayed in Figure 9.22. A reaction network for hydrocarbon isomerization is shown in Figure 9.22. 

Ueno, Y., Kobayashi, Y., Nagasaka, Y. Nagashima, A. (1991). Thermal conductivity of CFC alternatives. Measurements of HCFC-123 and HFC-134a in the liquid phase ly the transient hot-wire method. Trans. Japan Soc. Mech. Eng. (in Japanese), STB, 3169-3175. 

If an ITO layer is used on each substrate, a small voltage (30 V) can be applied across the film during the cooling cycle (after it has been heated to the isotropic liquid by a method such as (1)), so that homeotropic alignment of the transient N phase is electrically aided this then causes alignment of the smectic phase [26]. 

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