Dispersion permissible

Fig. XVII-31. (a) Nitrogen adsorption isotherms expressed as /-plots for various samples of a-FeOOH dispersed on carbon fibers, (h) Micropore size distributions as obtained by the MP method. [Reprinted with permission from K. Kaneko, Langmuir, 3, 357 (1987) (Ref. 231.) Copyright 1987, American Chemical Society.]...

Rosin sizing usually involves the addition of dilute aqueous solutions or dispersions of rosin soap size and alum to a pulp slurry (44—46). Although beater addition of either coreactant is permissable, addition of both before final pulp refining is unwise because subsequently exposed ceUulose surfaces may not be properly sized. The size and alum should be added sufficiendy eady to provide uniform distribution in the slurry, and adequate time for the formation and retention of aluminum resinates, commonly referred to as size precipitate. Free rosin emulsion sizes, however, do not react to a significant degree with alum in the pulp slurry, and addition of a cationic starch or resin is recommended to maximize retention of size to fiber. Subsequent reaction with aluminum occurs principally in the machine drier sections (47). 

FIG. 15-35 Extraction of diethylamine from water into toluene (dispersed) in towers packed with unglazed porcelain Raschig rings, To convert feet to meters, multiply hy 0,3048 to convert inches to centimeters, multiply hy 2,54, [Leihson and Beckman, Chem, Eng, Prog, 49, 405 (1953), with permission.)... 

FIG. 16-27 Constant pattern solutions for R = 0.5. Ordinant is cfor nfexcept for axial dispersion for which individual curves are labeled a, axial dispersion h, external mass transfer c, pore diffusion (spherical particles) d, surface diffusion (spherical particles) e, linear driving force approximation f, reaction kinetics. [from LeVan in Rodrigues et al. (eds.), Adsorption Science and Technology, Kluwer Academic Publishers, Dor drecht, The Nether lands, 1989 r eprinted with permission.]... 

FIG. 26-53 Effect of iuitial acceleratiou andhiioyaucy ou the release of gases. (Adapted from S. R. Hanna and F. J. TDtivas, Giiideliues for Use of Vapor Cloud Dispersion Models, 1987. Used hy permission of the American Institute of Chemical Engineers, Center for Chemical Fr ocess Safety. )... 

FIG. 26-54 Horizontal dispersion coefficient for Pasquill-Gifford plume model, Reprinted ffomD. A. Ct owl and J. F. Louvar, Chemical Process Safety, Fundamentals with Applications, Z.9.90, p. 138. Used hy permission of Ft entice Hall)... 

FIG. 26 57 Vertical dispersion coefficient for Pasqiiill-Gifford puff model. These data are based only on the data points shown and should not he considered rehahle elsewhere. (Reprinted from D. A. Cr owl and J. F. Louvar Chemical Process Safety, Fiiudanieutals with Applications, 1990, p. 140. Used hy permission of Prentice Hall. )... 

Equations (2) and (4) allow the permissible extra-column dispersion to be calculated for a range of capillary and packed columns. To allow comparison, data was included for a GC column, in addition to LC columns. The results are shown in Table 1. 

Table 1. The Permissible Extra-column Dispersion for a Range of Different Types of Column...

The maximum allowable dispersion will include contributions from all the different dispersion sources. Furthermore, the analyst may frequently be required to place a large volume of sample on the column to accommodate the specific nature of the sample. The peak spreading resulting from the use of the maximum possible sample volume is likely to reach the permissible dispersion limit. It follows that the dispersion that takes place in the connecting tubes, sensor volume and other parts of the detector must be reduced to the absolute minimum and, if possible, kept to less than 10% of that permissible (i.c.,1 % of the column variance) to allow large sample volumes to be used when necessary. 

The term three-phase fluidization requires some explanation, as it can be used to describe a variety of rather different operations. The three phases are gas, liquid and particulate solids, although other variations such as two immiscible liquids and particulate solids may exist in special applications. As in the case of a fixed-bed operation, both co-current and counter- current gas-liquid flow are permissible and, for each of these, both bubble flow, in which the liquid is the continuous phase and the gas dispersed, and trickle flow, in which the gas forms a continuous phase and the liquid is more or less dispersed, takes place. A well established device for countercurrent trickle flow, in which low-density solid spheres are fluidized by an upward current of gas and irrigated by a downward flow of liquid, is variously known as the turbulent bed, mobile bed and fluidized packing contactor, or the turbulent contact absorber when it is specifically used for gas absorption and/or dust removal. Still another variation is a three-phase spouted bed contactor. 

Ftgure 11 The electron micrographs of the final products and the variation of the monomer conversion with the polymerization time at different initiator concentrations in the dispersion polymerization of styrene. Initiator concentration (mol%) (a) 0.5, (b) 1.0, (c) 2.0. The original SEM photographs were taken with 2600 x, 2000 x, and 2600 x magnifications for (a), (b), and (c), respectively, and reduced at a proper ratio to place the figure. (From Ref. 93. Reproduced with permission from John Wiley Sons, Inc.)... 

Figure 14 The variation of average size of the polystyrene particles by the average solubility parameter of the homogeneous alcohol-water dispersion medium. (From Ref. 89. Reproduced with the permission of John Wiley Sons, Inc.)...

Figure 4-1. Characteristics of dispersed particies. By permission, Perry, J. H., Ed., Chemical Engineers Handbook, 3rd. Ed., 1950, McGraw-Hill Company, Inc.

Figure 5-5X. Type R-500. Very high shear radial flow impeller for particle size reduction and uniform dispersion in liquids. By permission, Lightnin, (Formerly Mixing Equipment Co.) a unit of General Signal.

Figure 5-24F. Settled solids or layered liquids are quickiy dispersed by the direc-tionalized flow from the draft tube. By permission. Weber, A. R, Chem. Engr., Oct. 1953, p. 183 [23].

Using the minimum permissible water-to-cement ratio for the particular cement class and adding dispersants to increase the fluidity of the slurry. 

Fig. 19.4 Non-dispersive continuous stream infrared analyser. Reproduced by permission of Beckman Instrument Co.

Figure 12.4. Transient effect of an applied negative current (I=-20mA) on the reaction rate r of CyT, oxidation on Pt finely dispersed on Au supported on YSZ (solid curve) and on the catalyst potential Uwr (dashed curve). Conditions catalyst C2, T=42l°C, po2=14.8 kPa, pc2H4=0.l kPa, fiow=411 ml/min, open circuit rate ro=0.037xl0 6 mol/s.7 Reprinted with permission from Academic Press.

Figure 12.5. Ethylene oxidation on Pt finely dispersed on Au supported on YSZ.7 Effect of the current 1 on x 1, where x is the time constant measured during a galvanostatic transient experiment with I as the applied current x is obtained by fitting either r/r0=exp(-t/x) or l-exp(-t/x) to the experimental data depending on the sign of the current and whether the reaction is electrophilic or electrophobic, (a) Positive values of I for electrophilic (squares, T=371°C, pO2=18.0 kPa, Pc2H4=0-6 kPa) and electrophobic behavior (circle, T=421°C, p02=l 4.8 kPa, Pc2H4 CU kPa) (b) negative currents, electrophilic behavior (T=421°C, p02=14.8 kPa, pC2H4=0.1 kPa. Reprints with permission from Academic Press.

FIG. 18 SEM pictures of self-assembled layers of particles Ic prepared from latex dispersions of different pH value (substrate glass support modified with 3-AMDS, dipping time 1 h, latex concentration 3 mg/mL T = 23.5°C). (From Ref. 98, with permission from Elsevier, Amsterdam.)... 

FIG. 20 SEM pictures of particle assemblies after different numbers of alternating dipping steps into dispersions of anionic particles lb and cationic particles 2 beginning with lb. A glass substrate modified with 3-AMDS was used and dipped with sequence (a) lb only, (b) lb-2, (c) lb-2-lb, (d) (lb-2) X 2, (e) (lb-2) X 3, (f) (lb-2) X 5. (From Ref. 93, with permission from Elsevier, Amsterdam.)... 

Fig. 2.3 The development of polarity and asymmetric division in Saccharomyces cerevisiae. The diagram is reproduced in a slightly simplified form from the work of Lew Reed (1995) with the permission of Current Opinion in Genetics and Development, (a) The F-actin cytoskeleton strands = actin cables ( ) cortical actin patches, (b) The polarity of growth is indicated by the direction of the arrows (arrows in many directions signifies isotropic growth), (c) 10-nm filaments which are assembled to form a ring at the neck between mother and bud. (d) Construction of the cap at the pre-bud site. Notice that the proteins of the cap become dispersed at the apical/isotropic switch, first over the whole surface of the bud, then more widely. Finally, secretion becomes refocussed at the neck in time for cytokinesis, (e) The status and distribution of the nucleus and microtubules of the spindle. Notice how the spindle pole body ( ) plays an important part in orientation of the mitotic spindle.

Figure 17.6 (A) Temporal evolution of photoluminescence and UV spectra (B) of CdSe quantum dots dispersed in CHCI3 [29], (C) The evolution curves of the photoluminescence peak intensity of quantum dot films on four kinds of SiOx substrates [34], Reprinted with permission from references [29] (A) and [34] (B) copyright [2003], American Chemical Society and copyright [2006], American Institute of Physics.

Figure 11. X-ray diffraction patterns of PVP-protected metal nanoparticles (a) PVP-protected CuPd (Cu Pd = 2 1) bimetallic nanoparticles (b) PVP-protected Pd nanoparticles (c) PVP-protected Cu dispersion (d) physical mixture of (b) and (c) (Cu Pd = 2 1). (Reprinted from Ref [71], 1993, with permission from The Chemical Society of Japan.)...

Scheme 1. Inclusion of size-controlled PVP-protected Pt nanoparticles in calcined mesoporous SBA-15 silica matrices. Mechanical agitation by low-power sonication affords a high dispersion of nanoparticles ranging in size from 1 to 7nm in the mesopore channels. The method is referred to as capillary inclusion (Cl). The technique is limited by the size of nanoparticles that can fit into the 6-9 nm diameter mesopores [13]. (Reprinted from Ref [13], 2005, with permission from American Chemical Society.)...

Figure 1. TEM image of a titania supported gold catalyst (1.7wt.% Au) prepared by deposition-precipitation (gold particle size = 5.3+ 0.3 nm, dispersion = 36%). (Reprinted from Reference [84], 2000, with permission from American Chemical Society).

Figure 1. Graphical model for the generation of size-controlled metal nanoparticles inside metallated resins, (a) Pd is homogeneously dispersed inside the polymer framework (b) Pd is reduced to Pd (c) Pd atoms start to aggregate in subnanoclusters (d) a single 3 nm nanocluster is formed and blocked inside the largest mesh present in that slice of polymer framework (Reprinted from Ref [5], 2004, with permission from Wiley-VCH.)...

Figure 6. Size dispersion of Pd nanoclusters in Pd /DOMA-VP. (Reprinted from Ref [5], 2004, with permission from Wiley-VCH.)...

FIG. 20 23 Normalized photoluminescence spectra of 3.1-um ( excitation = 320 nm) and4.2-nm (Xexdtation = 340 nm) Ge nanoparticles dispersed in chloroform at 25 C with quantum yields of 6.6 and 4.6 percent, respectively. [Reprinted with permission from Lu et al. Nano Lett, 4(5), 969-974 (2004). Copyright 2004 American Chemical Society. ]... 

FIGURE 6.9 Dependence of viscoelastic parameters on solvent quality. The (A) static force, (B) drag coefficient at 10 kHz, (C) dynamic spring constant, and (D) dispersion parameter are shown as a function of the surface-sphere distance. The results for water, propanol, and a 50/50 water/propanol mixture are given. Reprinted with permission from Benmouna and Johannsmann (2004). 

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