The approaches to the theory of anesthesia have evolved from different ways. Clinicians and biologists have been proved the states of anesthesia, and determined the minimum alveolar anesthetic concentration as a standard anesthetic potency. The correlation between minimum alveolar anesthetic concentration and lipid solubility suggests that the molecular site of anesthetic action is hydrophobic region. Macro-and micro-analysis of anesthetic action on biological tissues and organs have been carried out. On the other hand, physicochemical approaches to the theory of anesthesia have been focused on biological membranes. The mechanism of anesthesia was concentrated on the perturbation of the membrane of the nerve cells. The most likely mechanism of anesthetic action involves synaptic membrane. Anesthetic molecules may block membrane pores by uncertain mechanisms including membrane expansion. Pressure reversal is an important evidence of anesthesia. Critical volume hypothesis is that anesthesia occurs when a hydrophobic region is expanded by a critical volume and high pressure opposes the expansion and reverses anesthesia.
The present paper was briefly reviewed on possible mechanisms of anesthesia in a special reference to the biological membranes.

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The reactor system combined with ultrafiltration (UF) membrane or hollow fiber tube is very useful for the continuous hydrolysis when the enzyme reaction is subjected to high polymer substrate such as protein and cellulose. The continuous bioconversion combined with hydrogenases and polymer-bound NAD (nicotinamide-adenine dinucleotide) was recently carried out by using UF membrane reactor. This type of bioreactor has more sophisticated biochemical function than the hydrolysis and the isomerization. The gel membrane containing microorganism or enzyme such as collagen-enzyme membrane has been applied as a biosensor in the field of analytical chemistry. The fiat gel membrane containing the yeast was recently applied to continuous ethanol production system, in which ethanol was efficiently produced for 5000 hrs by the yeast membrane. Polymerizable monomer combined with NAD, acrylamide and methylene-bisacrylamide was copolymerized in the presence of enzymes, and subsequently NAD and enzymes are entrapped in the gel membrane. The gel membrane is able to catalyze more sophisticated biochemical reactions such as oxygenation-reduction and biosynthesis by using the immobilized cofactors.

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The states of water and salts in synthetic membranes have been discussed with attention to their structural and dynamical aspects.
The states and the mobilities of water under the influence of near-by polar and non-polar groups and ions are reviewed. Hydration of charged poly (amino acid) s as studied by a preferential solvation study is discussed. Diffusion of water and various solutes in synthetic membranes are reviewed from the viewpoint of dual mode diffusion. Change in the hydration of salts in membranes and its influence on their mobilities are discussed by referring to the studies on the permeation of salts in poly (vinyl alcohol) and crown-etherized poly (vinyl alcohol) membranes. A discussion follows on the discrimination of alkaline metal cations by poly (glutamate) in forming the helix conformation.

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Spheroplasts of a Synechococcus sp. thermophilic cyanobacterium showed cyclic photophosphorylation activity of 1200μmolATP/mg Chlh at 45 C with ascorbate-phenazine methosulfate, and non-cyclic activity of 11μmol ATP/mg Chl h with H₂O-methyl viologen. Thylakoid membranes exhibited less than one-tenth of the spheroplasts activities in both types of photophosphorylation. The spheroplasts gave optimal cyclic phosphorylation at 55°C and lost half of the activity at 67°C for 5min. It was suggested that the stability of the photosynthetic membranes to retain proton gradient across the membranes might be closely related to the thermostability of the photophosphorylation.

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Freezing or freeze-drying caused a decrease in the liposome size and an increase in water permeability of large multilamellar liposomes made of phosphatidylcholine and cholesterol (0%, 10%, 33% in mole ratio), but no size reduction with partially-sonicated liposomes. Cold storage at -27°C up to 45 days resulted in no change in water permeability, although the proportion of fragmented liposomes increased. On the other hand, the cold storage caused significant increase in permeabilities of hydrophilic amino acids such as Gly and Pro with phosphatidylcholine multilamellar liposomes. These results indicate that freezing, freeze-drying, and cold storage induce an increase in the structural defect of lipid bilayer as well as increase in mobility (or disorder) of lipid bilayer.

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Amorphous ultrafine paticles were dispersed in cellulose acetyl membrane by facing each side of the membrane with aq. NaOH and aq. Fe(NO₃)₃. Dispersed fine particles layer was formed in proportion to the hydrosis of cellulose acetate. This homsgeneous hybrid membrane looks like a brownish solid solution. The fine particles were directly converted into ferromagnetic Fe₂O₃ by thermal decomposition of the hybrid membrane. Gas permeabilities have been investigated for freeze-dried hybrid membrane.

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Reverse osmotic concentration of aqueous 1, 2 ethanediol solution was carried out using composite membrane PEC-1000 supplied from Toray Co. Ltd. Separation of 1, 2 ethanediol and flux through the membrane were measured under the following conditions : concentration of 1, 2 ethanediol; 2.9, 5.2, 9.8, and 12.8 wt%, operating pressures; 2.9, 3.9, 5.5, and 6.9 MPa. Measured separation were around 95% at lower solute concentration, but less than 85% at higher solute concentration and medium operating pressure.
An analysis of the data with Spiegler-Kedem's transport model shows that the values of reflection co-efficient σ, solute and hydraulic permeabilities ω and Lp were 1.0, 4.6 × 10^-11 and 1.28 × 10^-7 mol./ (m²·Pa·s), respectively.
Energy and membrane area required were calculated to concentrate dilute 1, 2 ethanediol solutions by reverse osmosis. The energy per one kilogram of the concentrated 1, 2 ethanediol is proportional to the operating pressure and slightly depends on final concentration and concentration polarization, and found 0.1 to 0.25 kWh to concentrate upto 13.2 wt% from 1.3 wt%. The membrane area is inversely proportional to the operating pressure and found 0.05, 0.07 and 0.11 m/ (kg 1, 2 ethanediol/day), for 10, 8, 5 MPa at no concentration polarization to concentrate. upto 13.2 wt%. The area is strongly dependent on concentration polarization

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