Collodion membrane

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... 

Simple osmometers have also been developed by Adair particularly for aqueous colloidal solutions. A thimblc-typc collodion membrane is attached to a capillary tube and contains the solution, When equilibrium is established the difference in level inside and outside the capillary is measured, Capillary corrections are made. For organic solvents a dynamic type osmometer may be used. A membrane of large surface area is clamped between two half cells and attached to each half cell is a fine capillary observation tube. With such an apparatus, equilibrium is rapidly established between solution and solvent contained in the half cells, The volume of the half cell may be small (about 20 cubic centimeters), The level of the solvent is usually aiiangecl to be a little below the equilibrium position, and the height of the solvent in the capillary as a function of time is measured, This procedure is repeated with the level of the solvent just above the equilibrium position. A plot is then made of the half sum of these readings. 

As a negative membrane was used a collodion membrane at which... 

Bechhold prepares collodion membranes of graded pore size, measures bubble points and uses the term ultrafilter -1907... 

Attempts to determine the molecular weight of colloidal ferric hydroxide lead to very high values. Thus, a colloidal solution prepared by addition of ammonium carbonate to ferric chloride solution was purified by dialysis, and the freezing-point determined of that portion which would not pass through a collodion membrane. The point was only slightly lower than that of the filtrate, indicative of a molecular weight of 3120 for the colloid.2... 

A Ithough the adsorption of polymers onto solid surfaces has been thor-oughly studied (I), relatively few studies can be found in the literature on the adsorption of proteins onto polymer surfaces. In 1905, Landsteiner and Uhliz (2) discussed the interaction of serum proteins with synthetic surfaces. Blitz and Steiner (3) showed that albumin adsorption onto solid surfaces increased with increasing albumin concentration and that adsorption was nearly irreversible. Hitchcock reported (4) that adsorption of egg albumin onto collodion membranes followed a Langmuir isotherm with maximum adsorption occurring near the isoelectric point. Later, Kemp and Rideal (5) reported that protein adsorption onto solids conforms with Langmuir adsorption. 

Many thermodynamic properties of lactose are known, including its heat of combustion," -" of solution, " and of dilution" its heat capacity," " " entropy," and free energy " its mean energy and entropy of activation through a collodion membrane and the specific heats of lactose solutions. ... 

Table IV. Influence of Casting-solution Water Concentration upon Pore Size and Permeability of Collodion Membranes...

The colorimetric method fails in solutions which are very darkly colored or extremely turbid. Frequently this difficulty may be overcome by the dialysis method, especially when the colored substance is colloidal. The investigated solution is placed in a thimble of pure parchment or in a collodion membrane set in a little pure water. After it has been ascertained that the pH of the external water no longer varies, its acidity is measured colori-metrically. The time required is usually twelve hours or less, and must be determined for each case. The author has obtained good results by this method when used to measure the pH of soil extracts, milk, emulsions, etc. 

The Golay cell uses the distortion of a reflecting Sb-coated collodion membrane, closing one of the ends of a so-called pneumatic chamber. This distortion is caused by the thermal expansion of a gas heated by the radiation incident in the cell, and produces the deflection of a beam of visible light, which is detected by a photocell. The Golay cell was used, fitted with a diamond window, with the first far IR FTS and its responsivity and response time were comparable to those of the radiation thermocouple. For more details on these detectors, see [15]. 

At the turn of the century (1906), Bechhold produced graded pore sizes in collodion membranes and measured the pore size with the "bubble-point" method (to be described later). 

The beginnings of ultrafiltration (UF) are coincident with that of reverse osmosis (RO) around 1960. Despite the fact that the term "ultrafiltration" first appeared in the colloid literature toward the end ofthe last century and Bechhold, in 1906 produced collodion membranes with pore sizes below 0.01 micron, these membranes were little more than laboratory curiosities. The hydraulic permeability was low and the pores were easily plugged. 

Bioactive sorbents represent the simplest form of artificial cells already used in routine clinical applications for humans. Sorbents such as activated charcoal, resins, and immunosorbents could not be used in direct blood perfusion because particulate embolism and blood cells were removed. However, sorbents such as activated charcoal inside artificial cells no longer cause particulate embolism and blood cells removal. This application was developed and used successfully in patients. For example, the hemoperfusion device now used in patients contains 70 g of artificial cells. Each artificial cell is formed by applying an ultrathin coating of collodion membrane or other polymer membranes on each of the 100-p-diameter activated-charcoal microspheres. The mass transfer for this small device is many times higher than that for a standard dialysis machine. 

Bechold [6] reported one of the first careful studies of pressure to drive a membrane separation process. He developed a series of membranes from nitrocellulose with graded porosities and demonstrated how to characterize them through bubble tests [7]. The origin of the word ultrafiltration is attributed to Bechold [8]. Subsequent improvements to Bechold s process led to the first commercially available microporous collodion membranes and the birth of the membrane industry [7]. 

In reviewing the history of the search for the origin of the cellular electrical potential, I discovered the following each of the three models originally chosen for study as models of the cell membranes (oil layer, glass membrane, collodion membrane) eventually was discovered to generate the potential not by virtue of their ionic permeabilities. Rather, they are all surface adsorption potentials. 

We present in this section some interesting results concerning the membrane-electrolyte interface properties in the case of a collodion membrane.The membranes are collodion thick films (sslO m) made from a 4% collodion solution in diethylether these membranes contain fixed negative electrical charges inside. The electrolyte on both sides of the membrane is aqueous NaCl (concentration 2 x 10 -0.1 mol/liter), the active membrane surface is 1.2 cm, and the electrodes are made of platinized platinum. The power spectrum corresponding to the noise emitted by the total system is... 

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