Mixing reproducibility

Fig. 10.6. Linear mode positive-ion MALDI-TOF spectra of ribonuclease B in 80 mM urea, (a) 300 fmol in CHCA, (b) 600 fmol in DHB, and (c) 300 fmol in CHCA/DHB matrix mix. Reproduced from Ref. [71] by permission. Elsevier Science, 2003.

Figure 3.3 Solution process polystyrene reactors as a function of axial and radial mixing. Reproduced with permission from Encyclopedia of Polymer Science and Engineering, Mark (Ed.), John Wiley Sons, NY. Copyright John Wiley Sons...

Figure 5 Calculated fractional crystallization trends for group IIIAB iron meteorites using several different types of models. The simple fractional crystallization models assume a perfectly mixed liquid whereas the other four models assume different types of imperfect mixing (reproduced by permission of the Meteoritical Society from Meteorit.

Figure 10, Freeze-fracture electron micrograph of inhomogeneous gel structure produced by inadequate mixing, (Reproduced with permission from ref, 25, Copyright 1985 American Petroleum Institute,)...

Figure 12. Reproducibility of viscosity data. Two sets of data are superimposed and show excellent reproducibility. Data were taken at ambient temperature in an RSIV rheometer with a Couette geometry and by using impingement mixing. Reproduced with permission from ref. 27. Copyright 1987 American...

Figure 43. Series of X-ray patterns of a commercial nonionic lamellar phase, formed by fast mixing (reproduced from [192]).

Fig. 4 Numerical simulations to calculate the pulse frequency for optimised mixing for the microfluidic synthesis of ZnO nanoparticles (a) 1 Hz pulse mixing, (b) 3 Hz pulse mixing and (c) 5 Hz pulse mixing. Reproduced with permission from ref. 19. Copyright 2014 Royal Society of Chemistry...

Fig. 7. Allergic contact dermatitis to black rubber in a work boot. Note the hyperkeratotic scaling dermatitis most pronounced over the metatarsal area and tips of the toes. This pattern, together with sparing of the interdigital webs, the toe creases and the arch of the foot should suggest the diagnosis. Patch tests were positive to N-isopropyl-N -phenylparaphenylenediamine (IPPD) and black rubber mix. Reproduced with the permission of Donald V. Belsito, M.D., Division of Dermatology, University of Kansas Medical Center, Kansas City, KS...

Pig. 4. (a) Scheme of initial morpholep development, (b) Holes and lace structure observed in ribbons at 1.0 min mixing, (c) Broken lace structure and small spherical particles at 1.0 min mixing, (d) Morphology of the dispersed phase particles at 1.5 min mixing, (e) Morphology of the dispersed phase particles at 7 min. mixing. Reproduced with permission from Reference 64. 

Figure 8-7. F factor for single pass cross-flow exchanger (one fluid mixed). (Reproduced with permission from reference 3. Copyright 1940, American Society of Mechanical...

Figure 3.12 Phase structures observed in PS/PA 80/20 (wt%) blends prepared in an internal mixer after selective dissolution of PS matrix, (a) After 60s of mixing (b) After 90s of mixing. Reproduced with permission from Ref. [61] 1991, Springer.

Figure 8. A plot of 3030 cm" versus 3048 cm peak ratio as a function of temperature for both mixes. (Reproduced with pennission from ref. 7. Copyright 1992 Elsevier Science Publishers B.V.)...

Barnes and co-workers have studied mixed-monolayer systems [278,281,283,284] and found some striking nonidealities. Mixed films of octadecanol and cholesterol, for example, show little evaporation resistance if only 10% cholesterol is present [278] apparently due to an uneven granular microstructure in films with cholesterol [284]. Another study of cellulose decanoate films showed no correlation between holes in the monolayer and permeation rate [285]. Polymerized surfactants make relatively poor water evaporation retarders when compared to octadecanol [286]. There are problems in obtaining reproducible values for r [287] due to impurities in the monolayer material or in the spreading solvent. 

Figure Bl.27.6. A calorimeter for enthalpies of mixing in the absence of a vapour space. (Reproduced with pennission from Larkin J A and McGlashan ML 1961 J. Chem. Soc. 3245.)...

Quantum chemical methods, exemplified by CASSCF and other MCSCF methods, have now evolved to an extent where it is possible to routinely treat accurately the excited electronic states of molecules containing a number of atoms. Mixed nuclear dynamics, such as swarm of trajectory based surface hopping or Ehrenfest dynamics, or the Gaussian wavepacket based multiple spawning method, use an approximate representation of the nuclear wavepacket based on classical trajectories. They are thus able to use the infoiination from quantum chemistry calculations required for the propagation of the nuclei in the form of forces. These methods seem able to reproduce, at least qualitatively, the dynamics of non-adiabatic systems. Test calculations have now been run using duect dynamics, and these show that even a small number of trajectories is able to produce useful mechanistic infomiation about the photochemistry of a system. In some cases it is even possible to extract some quantitative information. 

Pentaerythritol tetranitrate is a high energy explosive that is used as a pressed base charge in blasting caps and detonators, as the core explosive in commercial detonating cord, and as the main explosive ingredient in sheet explosives. It is also mixed in various proportions with TNT to form the less sensitive pentoHtes, eg, PETN 50/TNT 50. PETN is easily initiated, its responses are reproducible, and it is readily available (144—146). 

Of all these, probably P-phenethyl alcohol (2) comes closest to the odor of fresh rose petals however, mixing all these components does not reproduce the total fine character of the natural oil. It has been determined that a number of trace constituents representing less than 1% of the volatiles are critical to the development of the complete rose fragrance (10). These include cis- and trans-i.ose oxide (1), nerol oxide (12), rose furan (13), /)i7n7-menth-l-en-9-al (14), P-ionone (15), P-damascone (16), and P-damascenone (3). 

To obtain reproducible antibiotic production by fermentation, it is necessary to obtain a pure culture of the producing organism. Pure cultures are isolated from mixed soil sample populations by various streaking and isolation techniques on nutrient media. Once a pure culture has been found that produces a new antibiotic typically on a mg/L scale, improvement in antibiotic yield is accompHshed by modification of the fermentation medium or strain selection and mutation of the producing organism. Production of g/L quantities may take years to accomplish. 

There are direct substitutions of possible interest that would not be feasible without drastic changes in the feed system or pressure. Thus if the available substitute for natural gas is, eg, a manufactured gas containing much CO, there would almost always be a mismatch of the WIs unless the fuel could be further modified by mixing with some other gaseous fuel of high volumetric heating value (propane, butane, vaporized fuel oil, etc). Moreover, if there are substantial differences in eg, as a result of the presence of considerable H2 as well as CO in the substitute gas, the variation in dame height and dashback tendency can also make the substitution unsatisfactory for some purposes, even if the WI is reproduced. Refinements and additional criteria are occasionally appHed to measure these and other effects in more complex substitution problems (10,85). 

Close examination of each circular spot revealed a small forest of erosion cones (Fig. 11.35). Erosion was caused by the impingement of high-velocity steam probably mixed with droplets of condensate. The circular, equally spaced erosion sites apparently reproduced corresponding, equally spaced circular openings in the exhaust inlet. Compare Case History 11.3. 

Oxygen concentration is an especially important parameter to metals exposed to aqueous environments. Temperature and temperature gradients should also be reproduced as closely as possible. Concentration gradients in solutions also should be reproduced closely. Careful attention should be given to any movement of the corrosive medium. Mixing conditions should be reproduced as closely as possible. 

SEC is very easy to perform up to the production scale and the results are very reproducible. Because no gradient elution has to be applied, no programmable gradient mixing system is necessary and only comparatively simple equipment is needed for the operation. Additionally, the method can be integrated easily in purification schemes and most of the operational steps can be... 

This equation is based on experience with liquid chromatography of low molecular weight samples displaying single peaks. Its application for the GPC of polymers, however, contains a disadvantage, as it mixes two inseparable properties the retention difference for the separation and the peak width for the contrary effect of band broadening. Such a procedure is acceptable if both effects are accessible for an experimental examination. For the GPC experiment, we do not possess polymer standards, consisting of molecules that are truly monodisperse. Therefore, we cannot determine the real peak width necessary for a reliable and reproducible peak resolution R,. This equation then is not qualified for a sufficient characterization of a GPC column. 

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