Methods of quenching

The purpose of the majority of quenching experiments (particularly, with aqueous silicate and aluminosihcate systems) in capsules is not the solubility measmements, but a determination of phase relations in the multi-component systems at high parameters. Only in some cases, methods of microanalysis make it possible to determine compositions of quenched liquid and fluid phases. Defining a phase boundary on a diagram is usually done by drawing a fine between the points corresponding to various phase associations. The uncertainty of those phase boundaries depends not only on the experimental errors, but also on the density of the points on the diagram. 

A very important feature of capsule techniques in quenching experiments is the possibility of using the buffers. Buffers are flie additional phases placed in a charge capsule or in the second capsule in the experiments with hydrothermal systems to control the activity of some components. Most often it is tiie acidity of aqueous fluid. This approach to the study of natural hydrothermal systems, where the activity of one (or several) of the system s component(s) (for example pH or fugacity of O2, H2, S2, CO2) is under control of special reactions, was developed by Eugster (1957) and is widely used in experimental geochemistry. Details of the buffer technique have been reviewed by Huebner (Ulmer, 1971) and by Eugster et al. (Ulmer and Barnes, 1987). 

The most important change in the traditional design of cold-seal vessels is the possibility of conducting the internal isobaric quenching of samples by displacing the capsules from a hot to a cold region under experimental conditions 

One may note some other technical parts such as an electromagnetic device for shaking the capsule (Zharikov et al., 1985) to accelerate the reaction and to decrease the time for the equilibrium to be established. Detailed description of the device and experimental techniques for cold-seal vessels can be found in reviews by Kerrick (Ulmer, 1971 Ulmer and Barnes, 1987) and in the book (Zharikov et al., 1985). 

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The titration of an acid with a base, or vice versa, and the precipitation of an ion in an insoluble compound are examples of chemical methods of analysis used to determine the concentration of a species in a liquid sample removed from a reactor. Such methods are often suitable for relatively slow reactions. This is because of the length of time that may be required for the analysis the mere collection of a sample does not stop further reaction from taking place, and a method of quenching the reaction may be required. For a BR, there is the associated difficulty of establishing the time t at which the concentration is actually measured. This is not a problem for steady-state operation of a flow reactor (CSTR or PFR). 

In the case of cyclopropyl derivatives, although cyclopropyl methyl ketone gave a mixture of pentan-2-one and pentan-2-ol, cyclopropyl phenyl ketone afforded cyclopropylphenylmethane or cycloprop-ylphenylmethanol depending on the method of quenching (Scheme 2)P... 

We may also consider staged injection of one of the reactants as a method of quenching exothermic reactions cold hydrogen gas quench is used, for example, in hydrocracking of vacuum gas oils. 

Wilfong and Rolando [1993] extruded dry-blended polymer mixtures. To obtain mesopolymeric blends, it is necessary to rapidly cool the extmded product, and the shapes and thicknesses of the extruded materials are limited by the ability to cool them rapidly below 24°C. The methods of quenching included plunging in, or, spraying with a cold liquid, e.g., ice water, or running the extmded material over a cooled dmm or roll or both. 

When some commercial surfactants exhibited a precipitous drop in and efficiency between 0.5 and 5% water content, as did the nonionic surfactants Triton X-100 or Triton N-101, others behaved in a manner similar to our contrived nonionic-anionic surfactant mixtures. It is thus apparent that accurate calculation of the relative radioactivity of emulsified aqueous samples depends on rigorous uniformity of sample preparations. Optimal proportions of surfactants, surfactant content, and water content will depend on the nature and amount of the solute being counted. The usual methods of quench correction in LSC must be examined very carefully, inasmuch as they will usually not be adequate for determining absolute counting efficiency. 

Iwa] Method of quenching the melt in ice water after heating at different temperature over liquidus and investigation of stracture under light microscopy. Tammann carbon resistance furnace, electrolytic Fe and Cu, master alloy with 4.25 mass% C and graphite powder. Isothermal equilibria of two Uquids at 1450 and 1540°C in Fe comer at 0 to 4 mass% C and 0 to 30 mass% Cu... 

The composition of the complexes was established by the method of quenching of luminescence [23]. 

The key point in divalent Pd-catalyzed cyclization of allylic alkynoates is the method of quenching of the carbon-paUadium bond formed after cyclization. In order to develop a divalent Pd-catalyzed reaction, a divalent palladium species must be regenerated in the quenching of the carbon-paUadium bond. Lu and co-workers developed different quenching methods for the carbon-palladium bonds, for example, /3-heteroatom elimination, copper halide mediated oxidative cleavage, and carbonylation and protonolysis of... 

Method Starting Material Method of Quenching the C—Pd Bond Reaction Conditions Product Reference... 

Most methods of experimental physics, however, study equilibrated states of the sample under (preferably) stationaiy temperature conditions (usually chosen as isothermal). Apart from the direct low- and high-temperature investigations, most thermo-physical measurements are carried out at room temperatures, which, however, require a suitable method of quenching so as to preserve the equilibrated (mostly high-temperature) state of the sample down to the laboratory temperature. Such a thermal pretreatment is usually necessary to carry out outside the standard measuring head. 

Fires are classified into four major categories, based upon the substances involved, risks to the firefighter, and methods of quenching. 

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