Diffusion chamber

Figure 7 is a schematic representation of a section of a cascade. The feed stream to a stage consists of the depleted stream from the stage above and the enriched stream from the stage below. This mixture is first compressed and then cooled so that it enters the diffusion chamber at some predetermined optimum temperature and pressure. In the case of uranium isotope separation the process gas is uranium hexafluoride [7783-81-5] UF. Within the diffusion chamber the gas flows along a porous membrane or diffusion barrier. Approximately one-half of the gas passes through the barrier into a region... 

Typical approaches for measuring diffusivities in immobilised cell systems include bead methods, diffusion chambers and holographic laser interferometry. These methods can be applied to various support materials, but they are time consuming, making it onerous to measure effective dififusivity (Deff) over a wide range of cell fractions. Owing to the mathematical models involved, the deconvolution of diffusivities can be very sensitive to errors in concentration measurements. There are mathematical correlations developed to predict DeS as... 

Sirianni SR, Huang CC. 1980. Comparison of induction of sister chromatid exchange, 8-azaguanine- and ouabain-resistant mutants by cyclophosphamide, ifosfamide and l-(pyridyl-3)-3,3-dimethyltriazene in Chinese hamster cells cultured in diffusion chambers in mice. Carcinogenesis 1 353-355. 

In diffusing aerated confections under heating conditions, if the material can be processed at a high temperature, the bubble structure, after emerging from the diffusion chamber, will contract the air cell upon cooling, and thus become even smaller. 

Figure 5 The Costar Transwell system with a cell monolayer grown on a porous polycarbonate filter that is mounted onto a removable plastic insert forming the apical chamber. Two other systems, (1) the Costar diffusion chamber system, where a filter-grown (Snap-well) cell monolayer is sandwiched between two chambers of equal volume and the bathing solutions are agitated and/or gassed and (2) filter-grown cell monolayers mounted in a two-chamber rotating cylinder device (Imanidis et al., 1996), are not shown.

Using the side-by-side diffusion cell system, Hidalgo et al. (1992) quantified the transflux of testosterone in Caco-2 monolayers at 37°C as a function of the flow rate of the 02/C02 gas mixture (Table 13). They concluded that the kinetics were ABL-controlled and proceeded to calculate the ABL thickness on each side of the diffusion chambers using... 

Katz MA, RC Schaeffer Jr. (1991). Convection of macromolecules is the dominant mode of transport across horizontal 0.4 and 0.3 pm filters in diffusion chambers Significance for biologic monolayer permeability assessment. Microvasc Res 41 149-163. 

A diffusion chamber (Figure 1) originally designed for neutralization rate studies by Chu and Hopke (1985) has been modified to be an... 

This diffusion chamber was modified to provide a uniform flow from two channels at the entrance, one for the filtered room air and the other for the gas from the radon chamber. This modified mobility analyzer is schematically shown in Figure 2. The pressure heads are adjusted so that the gas velocities, v, are the same in both channels. An adjustable vertical electric field, E, is provided through the analyzer so that charged particles are drawn toward the detector located at x cm from the entrance. With the known distance, d, between the radon-laden gas channel and the detector implanted plate, the mobility can then be determined from... 

Keywords Buccal mucosa Permeability barrier Passive diffusion Excised tissue Nonkeratinized epithelium Diffusion chamber... 

Hwang KK, Jiang L, Ren Y, Martin LL, Martin NF (2002) Site-specific absorption of M100240 and MDL 100,173 in rats evaluated using Sweetana-Grass diffusion chamber technology. J Pharmacol Toxicol Methods 48 97-101. 

Either Transwell inserts or side-by-side diffusion chambers can be used for transport studies. Bode et al. have provided an excellent review on this subject [60], Briefly, cells are incubated for 30-60 min with a buffer solution. To initiate the transport study, a transport buffer containing the drug under investigation is added to either the apical or the basal chamber depending on the transport direction of interest. At predetermined time points, the respective receiver chamber is sampled and the withdrawn volume is replaced with the same volume of fresh buffer. The permeability coefficient (Papp) is calculated and the ratio of /apP in the basolateral-to-apical direction versus that in the apical-to-basolateral direction gives the efflux ratio. These sort of transport experiments are well suited to determine if drugs/xenobiotics are substrates of the placental efflux proteins. 

The intention to study transport processes at pulmonary epithelia, however, raised two particular problems (i) the apical side of these epithelia is typically in contact with air rather than with a liquid and (ii) in order to maximize the surface area, the lungs have a complex treelike structure, ending in millions of tiny alveolar bubbles. The total surface area of the human alveolar epithelium is almost half of that of the intestines (100-120 m2), with its macroscopic appearance resembling a sponge, and it is virtually impossible to use such a tissue for transport experiments in a diffusion-chamber setup. 

Keywords stem cell expansion stem cell culture in vitro diffusion chambers... 

The first batch of cells consisted of AC 133+ cells cultivated in the diffusion chambers submerged on top of the feeder (feeder -AC 133 cells /Fl-C). The second batch consisted of human embryonic liver cell suspension directly cocultured with AC133+ cells at equal initial quantities (5x10 ) in the diffusion chambers submerged in the 6-well plates without additional feeder layer (FC-C). Third batch of experiments represented AC133+ cells cultured in the DC surrounded by FL condition media (condition media-AC133+ cells/CM-C). In the control group cells were cultivated in the same condition without any additions and without feeder layers. 

Alternatively the membrane passage of human airway epithehal ceh lines can be studied in vitro. A number of bronchial epithehal ceh hnes is available, such as the 16HBE14o- and Calu-3 cell hnes. These ceh hnes can be installed in diffusion chambers to measure transport rates [34]. A major disadvantage of the currently used cell hnes is that they provide information about bronchial epithehal transport only. Since bronchial epithelium is very different from alveolar epithehum, the information from these in vitro studies is of limited value for the prediction of the bioavahabihty of pulmonary administered proteins. 

Rickard, M.D. and Bell, K.J. (1971 a) Immunity produced against Taenia ovis and T. taeniaeformis infection in lambs and rats following in vivo growth of their larvae in filtration membrane diffusion chambers. Journal of Parasitology 57, 571-575. 

Plasmacytomas. The transplantable plasmacytomas are derived from tumors induced in BALB/C mice. These tumors were induced by intraperitoneal (IP) implantation of plastic materials (Lucite discs or Millipore diffusion chambers) or by the IP injection of mineral oils (light and heavy medicinal mineral oils, Bayol,... 

Numerous surface-active molecules have been studied as GI absorption promoters in a wide variety of testing conditions, including model membranes, everted intestinal sacs, tissue cultures, intestinal epithelia in diffusion chambers, intact animals, and humans. The physical properties of a chemical enhancer may be strongly dependent on the interactions with the endogenous GI components such as bile salts, pH, and bacteria. Thus the in vitro experiments on enhancing GI absorption are not necessarily predictive of the behavior of the promoter in animals or humans, and we will mainly focus on summarizing results from in vivo studies. 

Jan Sehn Institute for Forensic Research, Toxicology Department, Cracow, Poland, under Jan Markiewicz. The Polish Scientist used the micro-diffusion chamber procedure, which does not permit the detection of Iron Blue.502 The detection threshold for other cyanides lies at 10 pg per kg sample material. 

Permeability Experiments. Three sets of in-vitro diffusion experiments were conducted 1) identical ethanol/saline composition in both diffusion chambers, 2) ethanol/saline in the donor chamber and saline in the receiver, and 3) saline in the donor and ethanol/saline in the receiver chamber. Tritium labeled 3-estradiol was added to the donor side and samples were taken from both compartments at predetermined times and read in a scintillation counter (Beckman Inst., San Ramon, CA). Effective permeability coefficients were then calculated after steady state was reached using the following equation ... 

Shono Y., Nishihara H., Matsuda Y., Furukawa S., Okada N., Fujita T., Yamamoto A. (2004) Modulation of intestinal P- glycoprotein function by cremophor EL and other surfactants by an in vitro diffusion chamber method using the isolated rat intestinal membranes. J Pharm Sci, 93 877-885. 

Karlsson J, Artursson P (1992) A new diffusion chamber system for the determination of drug permeability coefficients across the human intestinal epithelium that are independent of the unstirred water layer. Biochim Biophys Acta 1111(2) 204—210... 

Via a flow chamber The eluate stream is eiuiched with an element standard diffusing through the membrane from the diffusion chamber [141]. 

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