Capillary entrapment

The property of dried citrus pulp to be "wet" by oils has been described by Kesterson and Braddock (8). Washed orange pulp solids normally contain 0.5-1.5% ether extractible lipids. Also present is cuticular wax which gives lipophilic character to the pulp solids (9). Both the water holding capacity (WHO) which encompasses sorption and hydration phenomena, and oil holding capacity (OHC) which can be described in terms of adsorption and capillary entrapment of... 

A theoretical model whereby maximum peak capacity could be achieved by the use of 3-D planar chromatographic separation was proposed by Guiochon and coworkers (23-27). Unfortunately, until now, because of technical problems, this idea could not be realized in practice. Very recently, however, a special stationary phase, namely Empore silica TLC sheets, has now become available for realization of 3-D PC. This stationary phase, developed as a new separation medium for planar chromatography, contains silica entrapped in an inert matrix of polytetrafluoroethy-lene (PTFE) microfibrils. It has been established that the separating power is only ca. 60% of that of conventional TLC (28) this has been attributed to the very slow solvent migration velocity resulting from capillary action. 

Several studies have been performed in order to investigate the effect of liposomal size (Hirano and Hunt, 1985), lipid composition (Senior and Gregoriadis, 1982 Hirano et al., 1985), and lipid dose (Ellens et al., 1983, Kim et al., 1987) on the fate of liposomes after intraperitoneal administration. In the size range studied (0.048-0.72 Min), no size-dependent absorption could be expected (Hirano and Hunt, 1985). Particles larger than 22.5 pm are not expected to enter the lymphatic capillaries (Allen, 1956). After intraperitoneal administration of multivesicular liposomes (19 + 7 ym), Kim and Howell (1987a) and Kim et al. (1987) showed that liposomal entrapment of Ara-C prolongs the half-Ufe of the drug in the peritoneal... 

The recoverability of hydrocarbon from the subsurface refers to the amount of mobile hydrocarbon available. Hydrocarbon that is retained in the unsaturated zone is not typically recoverable by conventional means. Additional amounts of hydrocarbon that are unrecoverable by conventional methods include the immobile hydrocarbons associated with the water table capillary zone. Residual hydrocarbon is pellicular or insular, and is retained in the aquifer matrix. With respect to recoverability, residual hydrocarbon entrapment can result in volume estimate discrepancies as well as decreases in recovery efficiency. With increasing water saturation, such as when the water table rises via recharge or product removal, hydrocarbons essentially become occluded by a continuous water phase. This results in a reduction of LNAPL and product thickness as measured in the well at constant volume. When water saturation is decreased by lowering the water table (as during recovery operations), trapped hydrocarbons can remobilize, leading to increased recoverability. 

Fig. 4 Elution profiles for (A) propranolol (a), promethazine (b), and chlorprom-azine (c) applied separately on a 5-mm ILC column containing cytoskeleton-depleted red blood cell membrane vesicles entrapped in dextran-grafted agarose gel beads (1.4 /amol phospholipid, 0.5 mL/min) and (B), from left to right, acetylsalicylic acid, salicylic acid, warfarin, and pindolol on a capillary continuous bed containing liposomes immobilized by use of C4 ligands (1.0 /xmol phospholipid, 10 /xl./min). The elution volumes in the absence of lipid are shown (a0, b0, and c0, and the arrow, respectively). (Part A is reprinted with permission, with slight modification, from Ref. 26. Copyright 1999 Elsevier Science. Part B is reprinted with permission from Ref. 23. Copyright 1996 Elsevier Science.)...

Fig. 3. The gel-entrapped hepatocytes are located in the intra-luminal capillary space of the device. Culture medium is perfused through and over the gel-entrapped hepatocytes. The host animal s blood is circulated in the extracapUlary compartment between the capillary hollow fibers. (Modified from Dixit et al. [29])...

With decreasing packing size in SEC columns, the probability of physical entrapment of macromolecules increases. To estimate the molecular weight limit above which ultrafiltration will occur, we must first calculate an average radius of the interstices formed in a packed bed. This is done by assuming that the packed column consists of a bundle of capillaries in which the capillary radius can be estimated from the bed hydraulic radius ... 

The mercury reservoir and the capillary should be completely filled with mercury. There must be no entrapped air A special vessel useful in filling the HMDE was described by Kemula [24]. This vessel should be equipped with a ground joint corresponding to that of the capillary, and the end of the capillary should extend to within several millimeters of the bottom. 

The distribution of parenterally administered DEHP to soft tissues was studied in marmoset monkeys. Seven days after intravenous and intraperitoneal administration of 100 and 1,000 mg/kg doses in com oil emulsion, respectively, the lungs were the major tissue retaining DEHP label (Rhodes et al. 1986). Following intravenous administration, the concentration of DEHP in the lungs was 4,257 pg/g that in the liver, approximately 17 pg/g the testes, 5 pg/g and the kidney, 4 pg/g. The authors hypothesized that the DEHP in the lungs reflects entrapment of insoluble compound from the intravenous emulsion by alveolar capillaries. After intraperitoneal administration, the concentrations of label in the lung, liver, kidney, and testes were approximately 265, 80, 60, and 15 pg/g, respectively. Seven days after... 

Pressure release after the dwell period should be very slow until the initial expansion and relaxation has taken place. Typically, this is done with a bleeder valve or a capillary. Sudden pressure decay can result in microcracks or visible cracks as the still entrapped air expands. 

Fig. 6.33. Scanning electron micrograph of a capillary column packed with 5 pm ODS silica beads and entrapped in porous poly(methyl methacrylate-co-ethylene dimethacrylate-co-2-acrylamido-2-methyl-l-propanesulfonic acid). (Reprinted with permission from [63]. Copyright 2000 American Chemical Society).

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