Home About us Contact
|
Home About us Contact | ||
|
|
||
Separate Correlations (separate + correlation)
Selected AbstractsMinimum fluidization velocity and gas holdup in gas,liquid,solid fluidized bed reactorsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2002K Ramesh Abstract Experiments were performed to study the hydrodynamics of a cocurrent three-phase fluidized bed with liquid as continuous phase. Based on the 209 experimental data (with four liquid systems and five different particles) along with 115 literature data from six different sources on minimum fluidization velocity, a unique correlation for the estimation of minimum fluidization velocity in two-phase (ug,=,0) as well as in three-phase systems is developed. A data bank consisting of 1420 experimental measurements for the fractional gas phase holdup data with a wide range of variables is used for developing empirical correlations. Separate correlations are developed for two flow regimes observed in this present work. The proposed correlations are more accurate and simpler to use. © 2002 Society of Chemical Industry [source] Agricultural Growth and Inter-Sectoral Linkages in a Developing EconomyJOURNAL OF AGRICULTURAL ECONOMICS, Issue 3 2000N. Gemmell Does growth in the manufacturing sector of an economy spillover to agriculture, or do sectors share similar growth rates only when they share some common exogenous stimuli? The limited number of investigations of this issue, for cross-sections of countries, have found some evidence in favour of spillovers, though the methodologies used cannot readily separate correlation from causation. Adapting the Feder (1982) model of sectoral externalities to a time-series context, we examine how far agricultural output in Malaysia has been affected by inter-sectoral spillovers. Our results suggest that expansion of manufacturing output, though associated with reduced agricultural output in the short-run, is associated with agricultural expansion over the long-run. Service output growth on the other hand seems to have been inimical to agricultural growth in both the short- and long-runs, while causality testing supports the case for spillovers rather than "common causes". Evidence on sectoral productivity is consistent with neoclassical arguments suggesting that the benefits of higher productivity in manufacturing tend to spill over to agriculture, encouraging productivity convergence. [source] Structural modifications resulting from proton transfer in complexes of phenols with pyridine,JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 8 2005Irena Majerz Abstract The structural consequences of proton transfer in complexes of phenol (1), 2,6-dichlorophenol (2), 4-nitrophenol (3) and 2,6-dichloro-4-nitrophenol (4) with pyridine were analyzed on the basis of results of B3LYP/6,31G** calculations. Three methods of describing the progress of proton transfer are proposed: the O,H [d(OH)] and C,O [d(CO)] bond lengths and the fraction XPT of the proton transfer form, calculated from the values of the dipole moments. The d(OH) parameter reveals behaviour near to XPT and can be used as a universal measure of the degree of proton transfer. The d(CO) parameter gives nearly linear dependences for various structural parameters, but independent estimation of the specific effects of the substituents is necessary, as separate correlations for each complex are found. A role of resonance interaction in systems containing a p -NO2 substituent is demonstrated. Copyright © 2005 John Wiley & Sons, Ltd. [source] Substituent effects in reductions of heteroaromatic cationsJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 10 2002David Heyes Abstract A set of 11 each of 2,4,6-triphenylpyrylium, -thiopyrylium and - N -methylpyridinium tetrafluoroborates carrying a range of substituents in the phenyl rings were prepared. First and second wave reduction potentials were determined. For the thiopyrylium series there are linear correlations between scaled potentials (E°/0.05915) and summed Hammett constants for substituents in the pendant phenyl groups (,,=,2.29 and 3.38 for first and second waves respectively). For the pyrylium series, a good linear relationship (,,=,2.79) is obtained for all substituent patterns for the first wave reduction potentials, but for the second wave there are separate correlations for salts carrying substituents in the 4-phenyl and for those carrying substituents in 2- and 6-phenyls. For the pyridinium series, the first wave potentials show separate correlations for salts carrying substituents in the 4-phenyl and for those carrying substituents in 2-and 6-phenyls, but a single linear relationship for the second wave potentials. These are related to particular structural features in the cations, radicals and anions in each series. Rates and products were determined for reductions of the pyrylium and thiopyrylium cations by sodium cyanoborohydride and of all cations by sodium borohydride in acetonitrile solution. Reactions are first order in reducing agent and cation. Primary kinetic isotope effects were determined for borohydride reduction of the least reactive of each of the series of cations. Plots of logarithms of second-order rate constants against summed Hammett constants for substituents in the pendant phenyl groups are linear for all combinations of reagent and cation with 0.91 < , < 1.50 across all substituent patterns. For parent pyrylium and thiopyryliums, kBH4/kCNBH3,=,8.4,×,104 and 1.5,×,104, respectively, and for reductions by borohydride the reactivities of the pyrylium, thiopyrylium and pyridinium, series decrease in the order 1.4,×,105:8.8,×,103:1. Constant selectivities are not observed. Comparison of the correlations for electrochemical reduction and for hydride addition leads to the conclusion that charge neutralization in the hydride addition transition states runs ahead of bonding changes at the originating B,H bond. Copyright © 2002 John Wiley & Sons, Ltd. [source] | ||||||||||