Thermal trapping

Two examples of path-dependent micromechanical effects are models of Swegle and Grady [13] for thermal trapping in shear bands and Follansbee and Kocks [14] for path-dependent evolution of the mechanical threshold stress in copper. 

So, for given strain rate s and v (a function of the applied shear stress in the shock front), the rate of mixing that occurs is enhanced by the factor djhy due to strain localization and thermal trapping. This effect is in addition to the greater local temperatures achieved in the shear band (Fig. 7.14). Thus we see in a qualitative way how micromechanical defects can enhance solid-state reactivity. 

J.W. Swegle and D.E. Grady, Calculation of Thermal Trapping in Shear Bands, in Metallurgical Applications of Shock-Wave and High-Strain-Rate Phenomena (edited by L.E. Murr, K.P. Staudhammer, and M.A. Meyers), Marcel Dekker, New York, 1986, pp. 705-722. 

D.E. Grady and J.R. Asay, Calculation of Thermal Trapping in Shock-Deformation of Aluminum, J. Appl. Phys. 53, 7350 (1982). 

Mozumder s (1988) conjecture on electron thermalization, trapping and solvation time scales in liquid water is based on combining the following theoretical and experimental information ... 

The application of very low temperatures to detect, to thermally trap, and to characterize intermediates in enzyme-catalyzed reactions. This is made possible by the fact that each individual, elementary step in a reaction pathway has its own activation energy. Lowering the temperature reduces the fraction of molecules that can react in certain steps, thereby permitting otherwise reactive species to accumulate. 

The binding, reaction, or interception of a reactive molecular entity or transitory intermediate in a reaction pathway to convert the substance to a more stable form and/or remove that substance from the system. Trapping may involve binding or reaction with another molecular entity or involve the alteration of some parameter (e.g., thermal trapping) ... 

Thermal trapping is a simple technique because the supercritical fluid is simply depressurized in a cooled recovery container. Unforhmately, this technique is limited to nonvolatile components as high gas flow can lead to the loss of relatively volatile compounds. Even slightly volatile compounds can be led by aerosol formation. 

Chemical (thermal) trapping of this tautomer has been achieved by the combined reaction of py and SnMe2Cl2 to give [ (C5H5N-CH2-Re(0)-0) 2SnMe2Cl2][Re04]2. ... 

For the cyclooctatetraene (COT)-bicyclo[4.2.0]octa-2,4,7-triene system (125)-(126), earlier studies using an indirect method afforded an equilibrium composition at 100 C containing 0.01% of the bicyclic form (126) (AG = 6.8 kcal mol" less stable). The bicyclic form (126) has been prepared, however, by low-temperature dehalogenation of dibromide (127) and found to rearrange to COT at 0 °C ( a = 18.7 kcal mol" ). " Recently, a high-temperature thermal trapping technique has been utilized to assess more completely the transformation between (126) and (125) in a quantitative manner. ... 

The irradiation of cyclohexyl benzoylformate (62) yields the hydroxyphenyl ketene (63) by a Norrish Type II fragmentation process. If the ketene is generated in the presence of imines (64), successful thermal trapping results in the formation of p-lactams (65). 

Figure 7. A configuration coordinate diagram for electron trapping at a positively charged defect. The Coulombic trap depth for the hydrogenlike Is ground state of the shallowly-trapped electron is . (Here Ec is equivalent to Eb in Eq. (3).) a, the energy barrier to deep trapping, is less than Ec for the potential surface with a minimum at q. This condition facilitates relaxation to the deeply trapped state. For the surface with a mimimum at q", a is greater than c so that the shallow trap will thermally ionize rather than relax to the deeper trapped state. , is the thermal trap depth of the relaxed deep state and opI is its optical trap depth.

The energy estimated from the analysis of the emission assuming pair recombination may suffer the same problem but it would be, again, an overestimate. Thus it is concluded that the relaxed, self-trapped hole lies, at most, 400 meV above the valence band. The data from the EPR studies of the decay of the self-trapped holes yielded a thermal trap depth equal to or greater than lOOmeV [164],... 

M. H. Cobble, Irradiation into Transparent Solids and the Thermal Trap Effect, J. Franklin Inst. 278, pp. 383-393,1964. 

Fig. 6. Chemostat for continuous cultivation of Hydrogenomonas. 1 medium reservoir 2 pump 3 constant-level vessel 4 timer 5 valve 6 thermal trap 7 collecting vessel 8 flow meters 9 Waldhof cylinder...

A similar continuous culture system accommodating 41 liquid medium is in use in our laboratory for permanent production of cells needed for different kinds of experiments (Fig. 6). The vessel contains a double-walled Waldhof cylinder, which serves for heat transfer, and a stirrer which can be driven up to 2000 r.p.m. The flow of the incoming medium is controlled by a magnetic valve with timer and passes a thermal-trap heated to 70° C in order to prevent backgrowth of cells into the reservoir vessel. The gas supply is controlled by flow meters. With this system, a constant cell density of 3 g dry weight/1 could be maintained for months. 

The collection device stores the extracted analyte in one of three ways (a) via thermal trapping, (b) by sorbent trapping, or (c) by solvent trapping. 

E thermal trap depth (thermal correction M concentration of hole traps M... 

Figure 25 Selective disassembly of macro-Janus droplet assemblies, (a-e) Trigger 1 pH-induced disassembly at 5 s intervals, (f) Thermally trapped hemisphere at pH 9 and 20 °C. (g-j) Trigger 2 thermally induced disassembly of 1-dodecanol hemisphere on heating at 7 s intervals. Scale bars 1mm. (Reproduced from Ref. 61. Wiley-VCH, 2009.)...

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