Mean external length

L length of separation path column or tube length Lkj coefficient in Onsager s equation of reciprocity L mean external length of molecule or colloid m mass... 

Several size parameters can be used to describe the dimensions of polymer molecules radius of gyration, end-to-end distance, mean external length, and so forth. In the case of SEC analysis, it must be considered that the polymer molecular size is influenced by the interactions of chain segments with the solvent. As a consequence, polymer molecules in solution can be represented as equivalent hydrodynamic spheres [1], to which the Einstein equation for viscosity may be applied ... 

In hydrocarbon liquids other than n-hexane, the procedure for obtaining the thermalization distance distribution could conceivably be the same. However, in practice, a detailed theoretical analysis is rarely done. Instead, the free-ion yield extrapolated to zero external field (see Chapter 9) is fitted to a one-parameter distribution function weighted with the Onsager escape probability, and the mean thermalization length (r ) is extracted therefrom (see Mozumder, 1974 ... 

Polymer cable anodes are made of a conducting, stabilized and modified plastic in which graphite is incorporated as the conducting material. A copper cable core serves as the means of current lead. The anode formed by the cable is flexible, mechanically resistant and chemically stable. The cable anodes have an external diameter of 12.7 mm. The cross-section of the internal copper cable is 11.4 mm and its resistance per unit length R is consequently 2 mQ m l The maximum current delivery per meter of cable is about 20 mA for a service life of 10 years. This corresponds to a current density of about 0.7 A m. Using petroleum coke as a backfill material allows a higher current density of up to a factor of four. 

In a shell and lube heat exchanger with horizontal tubes 25 mm external diameter and 22 rnm internal diameter, benzene is condensed on the outside by means of water flowing through the tubes at the rate of 0.03 m Vs. If the water enters at 290 K and leaves at 300 K and the heat transfer coefficient on the water side is 850 W/in2 K, what total length of tubing will be required ... 

Porous alumina tube externally coated with a MgO/PbO dense film (in double pipe configuration), tube thickness 2.5 mm, outer diameter 4 mm, mean pore diameter 50 nm, active film-coated length 30 mm. Feed enters the reactor at shell side, oxygen at tube side. Oxidative methane coupling, PbO/MgO catalyst in thin film form (see previous column). r-750X,Pr ed 1 bar. Conversion of methane <2%. Selectivity to Cj products > 97%. Omata et al. (1989). The methane conversion is not given. Reported results are calculated from permeability data. 

The relaxation rates calculated from Eq. (15) are smaller than the measured ones at low field, while they are larger at high field. OST is thus obviously unable to match the experimental results. However, water protons actually diffuse around ferrihydrite and akaganeite particles and there is no reason to believe that the contribution to the rate from this diffusion would not be quadratic with the external field. This contribution is not observed, probably because the coefficient of the quadratic dependence with the field is smaller than predicted. This could be explained by an erroneous definition of the correlation length in OST, this length is the particle radius, whilst the right definition should be the mean distance between random defects of the crystal. This correlation time would then be significantly reduced, hence the contribution to the relaxation rate. 

Wheeler [16] proposed that the mean radius, r, and length, L, of pores in a catalyst pellet (of, for that matter, a porous solid reactant) are determined in such a way that the sum of the surface areas of all the pores constituting the honeycomb of pores is equal to the BET (Brunauer, Emmett and Teller [17]) surface area and that the sum of the pore volume is equed to the experimental pore volume. If represents the external surface area of the porous particle (e.g. as determined for cracking catalysts be sedimentation [18]) and there are n pores per unit external area, the pore volume contained by nSx cylindrically shaped pores is nSx nr L. The total extent of the experimentally measured pore volume will be equal to the product of the pellet volume, Vp, the pellet density, Pp, and the specific pore volume, v. Equating the experimental pore volume to the pore volume of the model... 

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