Lyonium ion catalysis


Equation (2.3) describes a straight line of zero intercept if is plotted versus the velocity gradient. Such a plot is shown in Fig. 2.2. Since the coefficient of viscosity is the slope of this line, this quantity has a single value for Newtonian liquids. Liquids of low molecular weight compounds and their solutions are generally Newtonian, but quite a few different variations from this behavior are also observed. We shall not attempt to catalog all of these variations, but shall only consider the other pattern of behavior shown in Fig. 2.2. This example of non-Newtonian behavior is described as pseudoplastic and is often observed when the material under study is a fluid polymer. Since Eq. (2.3) defines the coefficient of viscosity as the slope of a plot of versus velocity gradient, it is clear from Fig. 2.2 that pseudoplastic substances are not characterized by a single viscosity. The apparent viscosity at a particular velocity gradient is given by the ratio a5/(dv/dy). Inspection of Fig. 2.2 reveals that pseudoplastic materials appear less viscous at high rates of shear than at low rates.  [c.78]

Radioactive tracers account for about 20% of the worldwide market for consumables and reagents for life science research. In 1994 the value was estimated at about 300 million. The principal fuU line manufacturers are Du Pont—NEN Research Products (Boston, Massachusetts) and Amersham International (Amersham, U.K.). These companies share roughly equaHy about 85% of the radiochemicals worldwide market. In addition to an extensive line of catalog products, these suppHers offer custom labeling and custom synthesis services. The rest of the market is shared by producers of a limited range of products or services, such as ICN Biomedicals (Costa Mesa, California) and American Radiolabeled Chemicals (St. Louis, Missouri).  [c.439]

Sizing for the straight-lobe compressor is normally done using catalog data. Rotor lengths range from approximately one to two times the rotor diameter. Individual frame sizes within a given vendor s line may exceed these limits. Maximum tip speeds are in the 125 fps range with some units approaching 140 fps. The following relationship will permit size approximation if no catalog is available. It should be remembered that this is a rough size and that it may not be a standard with any of the vendors. It is helpful, however, to know at least one dimension from the vendor s line to make an estimate more meaningful.  [c.124]

Raman spectra of molecules and crystals are composed of a pattern of relatively sharp lines. The wavenumber scale for most vibrations extends from 50 cm to about 1800 cm with some molecular vibrations extending to 3500 cm Line widths are on the order of 1-5 cm" The Raman spectrum thus has a fairly high density of information and can be used as a fingerprint for the identification of unknown materials by direct comparison of the spectrum of the unknown with spectra in a reference catalog. An example for a series of strontium titanates is shown in Figure 4. This approach is widely used for NMR spectra. X-ray diffraction powder patterns, and infrared spectra as well. As with these other techniques, the success of fingerprinting depends on the availability of a complete, high-quality catalog of reference spectra. Catalogs of reference Raman spectra are much less complete than the corresponding catalogs for IR, ultraviolet, and nuclear magnetic resonance spectra. Users of Raman spectroscopy should compile their own reference spectra.  [c.435]

C. Starting provision. (Although most normal motors now are capable of across-the-line starts, some designs are not check catalog carefully on this point and specify requirement if different.)  [c.658]

Example. A trap on a 150 psi steam line has been found to be blowing live steam on the basis of contact pyrometer measurements taken immediately upstream and downstream of the trap. The catalog rating of the trap is 5,000Ib/hr at saturation temperature (°F sub-cooled) at 150 psi.  [c.341]


See pages that mention the term Lyonium ion catalysis : [c.487]    [c.475]   
Chemical kinetics the study of reaction rates in solution (1990) -- [ c.264 ]