THE method employed by Dale and Evans [1920] of finding the hydrogen ion concentration of blood is to place the blood in a small thin collodion tube and to suspend this in an isotonic saline solution. The whole is allowed to stand for about half-an-hour to allow equilibrium to be attained, and the hydrogen ion concentration of the outside solution is then determined by an indicator method. The hydrogen ion concentration of this solution is then taken as that of the blood. The hydrogen ion concentration determined by this method does not, however, according to Evans [1920] agree with the results obtainedby the use of a hydrogen electrode placed in the blood, the hydrogen electrode giving, in his hands, results which were about 0 2 PH smaller than those obtained by the dialysis method. The diffusion method is supposed to be
The reduction of some aminoacridines has been investigated by controlled potential coulometry. The number of electrons involved in the first reduction stage has been determined by a graphical treatment of the current‐time values obtained using a divided electrolysis cell. With the exception of 5‐aminoacridine the results confirm the values obtained indirectly by Kaye5.
Dried varnish is rich in many ester moieties, which may be broken down into small, soluble compounds
by esterase activity or alkaline hydrolysis. Two methods for varnish removal have been developed, including
the treatment of either lipase or RbOH / PEG-400 crown ether which allow aged oil varnishes or paint
coverings to be removed or thinned. These techniques are designed to proceed in a controlled manner without
damaging lower paint or base layers. Unfortunately, lipase did not react with the aged ester groups of dried
linseed oil varnish. Surprisingly, the varnish came off in the presence of Tris buffer alone which, in addition,
formed reactive metal complexes. A better choice was the use of high Mr alkali ion polyethylene glycol–400
(PEG-400) crown ether type chelates. PEG-400 complexes alkali ions including rubidium and other alkaliions
impeding the diffusion of their basic counter ions into lower varnish or paint layers. Possible migration
of alkali metal ions into the paint layer during alkaline varnish removal was determined by labelling the
cleansing solutions with 86Rb. Fortunately, varnish is degraded on the surface only. Lower paint or varnish
layers are not attacked even if chemically similar to the varnish or over painting to be removed as virtually no
86Rb was detected on the paint surface.
SOME work has been done previously (Taylor(25)) on the possibility of using the Donnan membrane equilibrium as a means of investigating the ions inside the blood corpuscles. The determinations in those cases were done at room temperature and very few precautions taken against loss of CO2, and on the whole the results were of more qualitative than quantitative importance. It was also desirable that the quantity of blood used should be not more than 30 c.c. so that one subject could supply the blood for the whole determinations. This gives the relationship between the pH's on both sides of the membrane. The sign of the potential difference will depend upon whether the indiffusible ion is an anion or a cation. The sign of the potential difference can be shown to be related to the sign of the charge on the protein ion in such a way that the side containing the indiffusible ion is positive when that ion is a cation and negative when it is an anion (Michaelis(20)
synopsisThe molecular structures of a series of chain-extended polycaprolactone diok were studied by nuclear magnetic resonance (NMR) and conventional wet chemical tech-
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