Capillary dynamics

Astrology helps to harness subtle forces, which have an influence on our subject matter. That there are physical forces at play has been demonstrated through studies such as crystallization experiments, and capillary dynamics but there is also a subtle, spiritual aspect we seek to capture as well. Our material subject is the magnet which gathers the energy and holds it. 

Examples of chiral CE separations of racemic drugs are the following. (/ )-(-)-ketoprofen has successfully been separated from ketoprofen and detected (Fig. 4).f (5)-(+)-ketoprofen is the active component. Also, simultaneous chiral separation of a basic drug compound, 2(/ )-A-[l-(6-amino-pyridin-2-ylmethyl) pip-eridin-4-yl]-2-[(l/ )-3,3-difluorocyclopentyl]-2-hydroxy-2-phenyl-acetamide, and its chiral acidic intermediate, (/ ,/ ) l-(2,2-difluorocyclopentyl)-phenylacetic acid, has been achieved by CE using a single-isomer CD, octakis (2,3-diacetyl-6-sulfo)-y-CD (ODAS-y-CD).P l Carnitine has been separated using 50 mM DM-p-CD in 20 mM phosphate buffer (pH 4.3) as chiral selector. The separations are done at 30° C in a fused-silica capillary, dynamically coated with triethanolamine present in the background electrolytes. 

PE PA-6, with maleated SEBS, SEBS-MA immiscible capillary/ dynamic Lim White, 1994... 

LDPE Polybutene 1 (PB) immiscible/ viscoelastic capillary/ dynamic Deri Behar, 1992... 

RhEPO is another complex sialoglycoprotein, with three N-linked and one 0-linked glycosylation sites, that has been extensively characterized by CZE and cIEF as described in previous sections. The comparison of rhEPO and uEPO has been reported on uncoated capillaries [40] and on capillaries dynamically coated with ionene [62]. Although increases in resolution and sensitivity are desirable, and the samples of uEPO corresponded to purified standards, these works showed the potential of discriminating between exogenous and endogenous EPO. 

In the second group of CZE separations, many different approaches have been published. The main goal has been to avoid Tf adsorption to the capillary walls. This problem has been overcome by working with covalently coated capillaries, in some cases with hydroxyethylcellulose in the running buffer [79,89,191,202], or silica capillaries dynamically coated with DAB [185,196,200,202], spermine [185], DcBr [55], or diethylentriamine (DETA) [201], In general, the methods performed in uncoated capillaries with dynamic coatings are slower than the ones performed with the commercial buffers. On the other hand, the methods using covalently coated capillaries are as fast (usually in less than 10 min of analysis time) as the methods developed with the commercial buffers. 

Considering capillary dynamics, the pressure drop term is often described by the Laplace equation, AP = 2yH, where y represents liquid surface tension and H represents the mean curvature of the liquid-gas interface associated with aU curves, C, passing through the surface. Furthermore, the character of a sufficiently smooth surface is through the invariant from differential geometry, the principal curvature of each curve, kj. The radii of curvature are the inverse of each principal curvature, A , = 1/r,. Considering the maximum and minimum radii of curvature at a point on a three-dimensional surface, the mean curvature can be calculated explicitly (see Appendix for more thorough derivation of the mean curvature parameter) ... 

Outside of the capillary dynamic approach, scaling arguments and dimensionless analysis can provide valuable insight into fluid physics on the micro-/nanoliter scale. An exhaustive review of these approaches has been conducted for a variety of microfluidic techniques [1]. However, for this article, we will strictly consider scaling metrics and dimensionless numbers pertinent to the surface-directed approach. 

By substituting Eq. 3 into Eq. 2 and subsequently utilizing modified Eqs. 2 and 4 with the general Washburn equation, one finds that capillary dynamics tend to follow Eq. 5 with a general geometry-dependent characteristic length scale, L [1] ... 

Molecular mean-field models of capillary dynamics... 

Rheometry (capillary/dynamic/melt-flow index) Filler dispersion... 

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