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At least 127 records · Page 7Linked to original sources
PubMed2006

Giant amplification of interfacially driven transport by hydrodynamic slip: diffusio-osmosis and beyond.

We demonstrate that "moderate" departures from the no-slip hydrodynamic boundary condition (hydrodynamic slip lengths in the nanometer range) can result in a very large enhancement--up to 2 orders of magnitude--of most interfacially driven transport phenomena. We study analytically and numerically the case of neutral solute diffusio-osmosis in a slab geometry to account for nontrivial couplings between interfacial structure and hydrodynamic slip. Possible outcomes are fast transport of particles in externally applied or self-generated gradient, and flow enhancement in nano- or microfluidic geometries.

Journal Article↗
PubMed1984

Evaluation of cleaning strategies for removal of biofilms from reverse-osmosis membranes.

An evaluation was made of the efficiency of five classes of chemical cleaning agents for removing biofilm from spirally wound cellulose acetate reverse-osmosis membranes receiving influent with high or low levels of combined chlorine. Each cleaning regimen utilized one or more of the following types of chemical: (i) surfactants and detergents, (ii) chaotropic agents, (iii) bactericidal agents, (iv) enzymes, and (v) antiprecipitants. Cleaning efficiency was tested in the laboratory on membrane material removed from operations at various intervals (2 to 74 days). Cleaning effectiveness was evaluated against nontreated control membranes and was scored by scanning electron microscopy and enumeration of surviving bacteria after treatment of the membranes. The combinations of classes which were most effective in biofilm removal were the anionic and chaotropic agent combination and combinations involving enzyme-containing preparations. Membranes receiving influent with high levels of combined chlorine were easier to clean but more susceptible to structural damage from prolonged exposure to combined chlorine. No treatment or combination of treatments was completely effective or effective at all stages of biofilm development.

Journal Article↗
PubMed1999

Oedema, Starling and pulse reverse osmosis: towards a possible biochemical marker for oedema.

Several conflicting theories have been proposed to explain the development of oedema. Pulse reverse osmosis (PRO) suggests that oedema occurs when the mean pulse capillary pressure exceeds the osmotic gradient between the plasma and the interstitial fluid. In order to test this concept mean arterial blood pressures and colloid osmotic pressures were taken in a group of healthy volunteers, a group of patients with bilateral ankle oedema and a group of treated hypertensives. Patients with oedema were found to have colloid osmotic pressures (COP's) which were significantly less than those of the healthy volunteers (p <0.001) and the treated hypertensives (p <0.001). The results support the oedema mechanism proposed by PRO and indicate that the relationship between blood pressure and COP may be a useful biochemical marker of oedema and its treatment. Further study is required to numerically quantify this relationship.

Analysis of Variance↗
PubMed1999

[A study on the endotoxin and bacterial contamination in reverse osmosis water and dialysis fluids].

OBJECTIVE: To evaluate the endotoxin (ET) and the bacterial contamination in reverse osmosis (RO) water and dialysis fluids for hemodialysis treatment. METHODS: Specimens of RO water and dialysis fluids were obtained at random from 18 hospitals in Beijing. ET was measured with chromogenic limulus amoeboeyte lysate (LAL) assay. Bacteriologic samples were processed on heterotrophic plate count agar with pour plate technique. The plasma IL-1, IL-6 and TNFalpha were tested with enzyme-linked immunosorbent assay (ELISA). RESULTS: The level of ET in RO water was 0.116 +/- 0.063 EU/ml, and the culture of bacteria had 2 positive results, both counting 100 CFU/ml. The level of ET was much higher in acid concentrate (Protocol B) than in basic concentrate (Protocol A). The culture of bacteria had 11 positive results in Protocol B concentration with 8 samples equal or higher than 2,000 CFU/ml. The culture of bacteria had only 3 positive results in Protocol A concentration, all being lower than 2,000 CFU/ml. Another investigation showed that the level of ET in dialysis inlet was higher than 0.5 EU/ml in 5 cases of a total of 16. Their plasma IL-1 and TNFalpha levels were significantly increased. CONCLUSION: Both ET and bacterial contamination exist in RO water and dialysate. It is essential to examine the level of ET and perform bacterial culture, as well as to disinfect RO and dialysate tank at regular intervals in order to reduce pyrogenic reactions.

Endotoxins↗
PubMed1996

The therapeutic significance of pulse reverse osmosis.

Pulse reverse osmosis (1) is a new theory of fluid balance and exchange which suggests that the mean blood pressure and osmotic gradient control fluid balance and that the pulse controls fluid exchange. In vitro testing has confirmed some of the physico chemical principles underlying the theory (2). The hypothesis suggests a relationship between mean capillary blood pressure and osmotic gradient. Imbalance in this relationship can be related to the development of hypertension, hypotension, oedema and shock. In an attempt to test this concept mean blood pressures and colloid osmotic pressures were measured and compared in a group of 50 healthy human volunteers. The results suggest a curvilinear correlation between the mean blood pressure and the COP.

Blood Pressure↗
PubMed1958

Experimental study of osmosis through a collodion membrane.

Experiments were carried out on a collodion membrane in order to study the factors that determine direction and magnitude of net flow of water across a membrane permeable to the solvent and to some of the solutes present. The solutes used were all non-ionic. When only one solute was present and there was no difference of hydrostatic pressure across the membrane, water flowed toward the side where its vapor pressure was lower, but the rate of transfer depended upon the nature of the solute: for a given difference in osmolality across the membrane, the rate increased with the molecular volume of the solute and reached its maximum with the solute to which the membrane was impermeable. These results led to the experimental demonstration that in the presence of two or more solutes of different molecular volumes, of which one at least can diffuse through the barrier, the net transfer of water can take place against its vapor pressure gradient. Some of the physicochemical and physiological implications of the data are discussed.

Collodion↗