A-factor ratios

Reactant Observed ratio Statistical ratio A-factor ratio... 

Activation-energy differences and A factor ratios derived from Arrhenius plots [51] ... 

The A-factor ratios for the reactions involving perfluoro-iso-propyl radicals are no greater than those for other radicals. 

In order to maximize the excitation, precautions have to be taken to avoid cross-talk between excitation and signal. Therefore differential probes are commonly used with a SQUID system Nevertheless, for the discussed defects the SQUID system has a lower excitation field by a factor of about 100 compared with the commereial system This we must keep in mind, when we compare measured signal to noise ratios. There is a potential to improve for small defeets, when eross-talk is managed very well. 

Calculate what the critical supersaturation ratio should be for water if the frequency factor in Eq. IX-10 were indeed too low by a factor of 10 . Alternatively, taking the observed value of the critical supersaturation ratio as 4.2, what value for the surface tension of water would the corrected theory give ... 

The argument is sometimes given that equation (Al.6,29) implies that the ratio of spontaneous to stimulated emission goes as the cube of the emitted photon frequency. This argument must be used with some care recall that for light at thennal equilibrium, goes as BP, and hence the rate of stimulated emission has a factor... 

The pyrolysis of CR NH (<1 mbar) was perfomied at 1.3 atm in Ar, spectroscopically monitoring the concentration of NH2 radicals behind the reflected shock wave as a fiinction of time. The interesting aspect of this experiment was the combination of a shock-tube experiment with the particularly sensitive detection of the NH2 radicals by frequency-modulated, laser-absorption spectroscopy [ ]. Compared with conventional narrow-bandwidth laser-absorption detection the signal-to-noise ratio could be increased by a factor of 20, with correspondingly more accurate values for the rate constant k T). 

Thus, a single extraction improves the separation of the solutes by a factor of 2.5. As shown in Figure 12.1, a second extraction actually leads to a poorer separation. After combining the two portions of the extracting phase, the concentration ratio decreases to... 

The CRR mode involves retarding the electron kinetic energies to a constant ratio of H /H where H is the energy passed by the analyzer. Thus, the energies are retarded by a constant factor. Spectra acquired in this mode ate less easy to quantify, but small peaks at low kinetic energies ate readily detected. This mode of operation results in spectra of constant relative resolution throughout. The relative resolution is improved in this mode by a factor of E. ... 

NTU p is the "exterior apparent" overall gas-phase number of transfer units calculated neglecting axial dispersion simply on the basis of equation 56, whereas NTU stands for the higher real number of transfer units (Nq ) which is actually required under the influence of axial dispersion. The correction factor ratio can be represented as a function of those parameters that are actually known at the outset of the calculation... 

Caustic Soda to Chlorine Balance. In 1988, the ratio of U.S. caustic soda to chlorine consumption was 0.96 1 (see Fig. 39). Since 1968 this ratio has ranged from alow of 0.88 1 (1978 and 1981) to a high of 0.98 1 (1969). No single factor can explain these variations, since caustic soda and chlorine, with few exceptions, have different markets and are therefore not driven by the same economic forces. This ratio is expected to trend upward over the next five years, however, since caustic soda consumption in the United States is forecasted to grow somewhat faster than chlorine consumption. It is expected that this ratio will remain within the range experienced in 1970—1990. Because caustic soda is co-produced with chlorine at a theoretical ratio of 1.1 1, a U.S. consumption ratio below that level results in excess avaHabihty of caustic soda. This material is typically shipped offshore to fill a significant export demand, and in 1988, for example, net U.S. exports of caustic soda amounted to 7.1% of production. 

For most purposes only the Stokes-shifted Raman spectmm, which results from molecules in the ground electronic and vibrational states being excited, is measured and reported. Anti-Stokes spectra arise from molecules in vibrational excited states returning to the ground state. The relative intensities of the Stokes and anti-Stokes bands are proportional to the relative populations of the ground and excited vibrational states. These proportions are temperature-dependent and foUow a Boltzmann distribution. At room temperature, the anti-Stokes Stokes intensity ratio decreases by a factor of 10 with each 480 cm from the exciting frequency. Because of the weakness of the anti-Stokes spectmm (except at low frequency shift), the most important use of this spectmm is for optical temperature measurement (qv) using the Boltzmann distribution function. 

Most chromium-based catalysts are activated in the beginning of a polymerization reaction through exposure to ethylene at high temperature. The activation step can be accelerated with carbon monoxide. Phillips catalysts operate at 85—110°C (38,40), and exhibit very high activity, from 3 to 10 kg HDPE per g of catalyst (300—1000 kg HDPE/g Cr). Molecular weights and MWDs of the resins are controlled primarily by two factors, the reaction temperature and the composition and preparation procedure of the catalyst (38,39). Phillips catalysts produce HDPE with a MJM ratio of about 6—12 and MFR values of 90—120. 

The width of molecular weight distribution (MWD) is usually represented by the ratio of the weight—average and the number—average molecular weights, MJM. In iadustry, MWD is often represented by the value of the melt flow ratio (MER), which is calculated as a ratio of two melt indexes measured at two melt pressures that differ by a factor of 10. Most commodity-grade LLDPE resias have a narrow MWD, with the MJM ratios of 2.5—4.5 and MER values in the 20—35 range. However, LLDPE resias produced with chromium oxide-based catalysts have a broad MWD, with M.Jof 10—35 and MER of 80-200. 

Uranium is subsequendy stripped reductively from the loaded solvent using a bleed stream of the raffinate acid to which ferrous iron has been added to reduce uranium to its nonextractable, quadravalent state. Raffinate is acid from which uranium has already been extracted. By controlling the organic-to-aqueous volume phase ratios in the extraction and stripping circuits, uranium is concentrated by a factor of approximately 70. 

This means that if the price ratio has decreased by a factor of four, then losses should be down by a factor of two. If the old optimum allowed a 2% loss, the new optimum would be closer to 1%. 

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