Membranes cellophane

The solution was then dialyzed through a cellophane membrane against 4 iiters of water for 10 hours, with stirring. The dialysis was repeated 2 additional times, with fresh amounts of water. To the dialyzed solution there was added 2 mi of 1 N hydrochloric acid, whereupon polyestradiol phosphate was precipitated as a white bulky precipitate. This was centrifuged off and washed repeatedly with 0.1 N hydrochloric acid. Thereafter it was dried in a vacuum desiccator. The yield was 3 g of polyestradiol phosphate. The analysis shows 0.65% of water, 1.35% of pyridine and 9,3% of phosphorus (calculated on a dry sample). 

The intestinal wall is covered by a mucus layer. This mucus layer prevents direct contact of the lumenal contents with the epithelial membrane. Mucus can be attached onto the lipid membrane by the aid of agar and hydrophilic filter scaffold [64, 65]. This allows the simultaneous assessment of dissolution and permeation. Food effects were adequately predicted using this method. Lofts son et al. used a cellophane membrane as a surrogate for the mucus layer [66]. 

In this way Goldman et al.2-5 incorporated papain and phosphatase in collodion membranes, and other authors6-7 have done likewise with several enzymes in cellophane membranes. It is important to note the work of Suzuki8 on collagen membranes as well as the work on enzyme reactors9,10... 

In order to confirm this suggestion, the author sutdied electrodialysis of a dichlorethane solution of the catalyst. A two-chamber dialysis apparatus was used with a cellophane membrane, (Fig. 6) in the left... 

Figure 8. Heat of transfer across a cellophane membrane (140)...

Perhaps the most important medical use of dialysis is in artificial kidney machines, where hemodialysis is used to cleanse the blood of patients whose kidneys have malfunctioned. Blood is diverted from the body and pumped through a cellophane dialysis tube suspended in a solution formulated to contain many of the same components as blood plasma. These substances—glucose, NaCl, NaHC03, and KC1—have the same concentrations in the dialysis solution as they do in blood, so that they have no net passage through the cellophane membrane. 

As can be seen, the sample is diluted with one of the reagents, air is also admitted, and the material, after mixing, is pumped through the dialyzer above the cellophane membrane and then discarded. The po-... 

The solution was then dialyzed through a cellophane membrane against 4 liters of water for 10 hours, with stirring. The dialysis was repeated 2 additional times, with fresh amounts of water. To the dialyzed solution there was added 2 ml of 1 N hydrochloric acid, whereupon polyestradiol phosphate... 

Experimental Determination. Experimentally, we measured the dialysis through a cellophane membrane, and Ficks equation was used in integrated form which involved not only the volumes V and V0 of the inside and outside compartments but also the somewhat uncertain area of the membrane, A, and its effective thickness, Ax, which is very difficult to evaluate. 

Number average molecular weights were determined in toluene using a Mechrolab high speed membrane osmometer with Schleicher and Schuell, type U.O. very dense cellophane membranes. Previous work has established that under these conditions diffusion of this type of polymer through the membrane is not detectable at molecular weights down to about 6000 (18). 

A. 1948 - Hassler studies osmotic properties of cellophane membranes at UCLA... 

The first electrode for urea was prepared by immobilizing urease in a poly-acrylcimide gel on nylon or Dacron nets. The nets were placed onto a Beckman electrode (NH J selective) (59). In a later development, the electrode was improved by covering the enzyme gel layer with a cellophane membrane to prevent leaching of urease into the solution (60). The urease electrode could be used for 21 days with no loss of activity. 

Santi, R, Catellani, R L., Massimo, G., Zanardi, G., and Colombo, R lonto-phoretic transport of verapamil and melatonin. 1. Cellophane membrane as a barrier. Int. J. Pharm. 92 23, 1993. 

A semipermeable membrane is a membrane with very small holes in it, of such a size that molecules of the solvent are able to pass through but molecules of the solute are not. A useful semipermeable membrane for measurement of osmotic pressure is made by precipitating cupric ferrocyanide, Cu2Fe(CN)g, in the pores of an unglazed porcelain cup, which gives the membrane mechanical support to enable it to withstand high pressures. Accurate measurements have been made in this way to over 250 atm. Cellophane membranes may also be used, if the osmotic pressure is not large (Fig. 16-8). 

Cellophane membrane held with rubber band... 

It is important that unbound I be thoroughly removed from the reaction mixture, after labeling, by chromatography with an anion exchange resin, or by dialysis through a cellophane membrane. Otherwise, unlabeled I may adsorb nonspecifically to the solid phase and increase background noise in the assay. 

In 1953 Clark, Wolf, Granger and Taylor [48] found that a shiny platinum cathode covered with a layer of cellophane is suitable for direct measurement of oxygen tension in whole blood. The cellophane membrane prevents the undesirable effects of the red cells on the electrode. However, the great electrical resistance of the membrane and the possibility of contamination of the reference electrode with surface-active biological materials does not allow the use of this electrode for analysis in all media. 

Levene mentioned in 1931 that he had been unable to hydrolyze the polynucleotide to the mononucleotides with this enzyme, and in 1937 Dubos continued the study of the enzyme. Schmidt and Levene came to the conclusion that the phenomenon is one of depolymerization of polytetranucleotides to the tetranucleotide state. They were unable to detect any reaction-product of small enough molecular size to diffuse through cellophane membranes, and found the freezing point of the solution remained unchanged during action of the enzyme. However, a mixture of the four mononucleotides dialyzed rapidly through cellophane and caused a considerable depression of the freezing point. 

Bowers, R.C., and Murray, R.W. 1966. Voltammetric membrane electrode study of the ion-exchange properties of cellophane membranes. Analytical Chemistry 38, 461-465. Breck, D.W. 1974. Zeolite Molecular Sieves Structure, Chemistry, and Use. Wiley-... 

Lowe et al. (1983) utilized the detection of protons produced during glucose oxidation by an optoelectronic sensor. Glucose oxidase was coupled to a transparent cellophane membrane together with the pH sensitive triphenylmethane dye bromocresol green. The membrane was... 

In an analogous approach, GOD immobilized by crosslinking with glutaraldehyde and BSA has been applied to a fluorescence optode for O2, covered with a cellophane membrane (Opitz and Lubbers, 1987). The relative fluorescence intensity as photometrically measured was proportional to glucose concentration up to 7 mmolA. 

---