Experimental definition

Since quench rates in simulations typically are artificially high, this leads to a special problem for comparison with experiment as well as to the question whether there is a more general way to determine the glass transition temperature from the structure of the system. The experimental definition of viscosity is certainly not apphcable to simulations. 

An acid is classically known as a substance whose aqueous solution (i) turns blue litmus red (ii) neutralizes bases (iii) reacts with active metals with the evolution of hydrogen and (iv) possesses a sour taste. A base is again classically known as a substance which in aqueous solution (i) turns red litmus blue (ii) neutralizes acids (iii) tastes offensive and (iv) gives a soapy feel. These given descriptions of acids and bases may also be regarded as being operational or or experimental definitions. 

It must however be pointed out that a sound experimental definition of a phase diagram can be obtained from the results of a number of concerted investigations such as thermal analysis, thermodynamic analysis, micrographic examination and phase analysis and identification by means of techniques such as X-ray diffraction measurements, microprobe analysis, etc. 

Considering now a few common methods and techniques for the experimental definition of a phase diagram, it may be useful to refer to their usual classification into two groups polythermal and isothermal methods. 

Experimental definition The dose, below which no effects are observed. 

Thus, we have found that the mechanisms of escape from a nonhyperbolic attractor and a quasihyperbolic (Lorenz) attractor are quite different, and that the prehistory of the escape trajectories reflects the different structure of their chaotic attractors. The escape process for the nonhyperbolic attractor is realized via several steps, which include transitions between low-period saddle-cycles coexisting in the system phase space. The escape from the Lorenz attractor consist of two qualitatively different stages the first is defined by the stable and unstable manifolds of the saddle center point, and lies on the attractor the second is the escape itself, crossing the saddle boundary cycle surrounding the stable point attractor. Finally, we should like to point out that our main results were obtained via an experimental definition of optimal paths, confirming our experimental approach as a powerful instrument for investigating noise-induced escape from complex attractors. 

Sherman and Eyring (54, 55), it is only recently that quantum mechanical techniques have become available for the treatment of chemisorption. In addition, lack of precise experimental definition of surfaces has made it difficult to construct proper surface models. It is expected that theoretical models of surfaces will become increasingly useful in the future owing to the active work being performed on these problems. 

To examine the fundamental basis on which experimental definitions depend, consider an adsorption experiment incorporating both volumetric and gravimetric measurements (sec Fig. 1). A measured amount, n, of a specified gas (for simplicity, adsorption of a single gas is considered here), is introduced into the system whose total volume, V, can be varied at con-... 

Detonation limits have been measured for various fuel-oxidizer mixtures. These values and comparison with the deflagration (flammability) limits are given in Table 7. It is interesting that the detonation limits are always narrower than the deflagration limits. But for H2 and the hydrocarbons, one should recall that, because of the product molecular weight, the detonation velocity has its maximum near the rich limit. The deflagration velocity maximum is always very near the stoichiometric value and indeed has its minimum values at the limits. Indeed, the experimental definition of the deflagration limits would require this result. 

For the experimental determination of the 0, it is necessary to quantify the light output of the direct chemiluminescent process. The experimental definition of the direct chemiluminescence quantum yield is given in Eq. 36, that is, the initial rate of photon production (/q ) per initial rate of dioxetane decomposition k )[D]o). Alternatively, the total or integrated light intensity per total dioxetane decomposed can be used. The /t )[Z)]o term is readily assessed by following the kinetics of the chemiluminescence decay, which is usually first order. Thus, from a semilogarithmic plot of the emission intensity vs. time, the dioxetane decomposition rate constant kjj is obtained and the initial dioxetane concentration [Z)]o is known,especially if the dioxetanes have been isolated and purified. In those cases in which the dioxetanes are too labile for isolation and purification, [/)]o is determined by quantitative spectroscopic measurements or iodometric titration. 

The experimental procedure to determine 4>wa is quite analogous to that discussed for The experimental definition is given by Eq. 38, in which all the terms have been already defined. Again the dioxetane decomposition rate constant kj) is determined by following the first-order kinetics of the DPA-enhanced chemiluminescence decay. The initial or total DPA fluorescence intensity is standardized with a suitable light standard, usually with luminol or the scintillation cocktail. The photomultiplier tube should be corrected for wavelength response. ... 

Here the isoelectric point has been taken to be the pH at which the substance has no net charge. The experimental definition is the pH at which the substance has zero mobility in an electrophoresis cell. In fact, these two values of pH differ so slightly, they are frequently used interchangeably, as is done here.)... 

The standard experimental definition of the transit time corresponds to the extrapolated intersection point of the short- and long-time current decays. By solving Eqs. (A 15) and (A 16) for their intersection point, we find... 

The precise experimental definition of a delay depends on the reactor being used and on the properties it is possible to measure. Thus, for a batch reactor, the recording of the pressure increase as a function of time allows the time for which the global rate d(Ap)/dt is at a maximum, to be determined. The intersection of the tangent to the curve Ap(t) at this point with the horizontal Ap = 0 gives the value of the delay. 

It is evident that the aceuracy of the experimental definition of equilibrium eonstants of the investigated proeess is insuffieient. Thus, the summarization of experimental data on solvent effeet on [9.60, 9.61] equilibrium eneounters several diffieulties. 

The extrapolation of scattering intensity to the lower limit of scattering angles gives the Hory-Huggins interaction parameter. The experimental definition of this value is... 

---