Effect of moisture on and kinetic features of the ultrafiltration rate of dialysis membrane.
The kinetic features of ultrafiltration of cellulose dialysis membrane stored under various humidity and temperature conditions were studied to obtain basic information of shelf-life characteristics of dialyzers. The ultrafiltration rate (UFR) decreased with time and the UFR-time curve suggested that the UFR would approach a certain equilibrium value. This phenomenon could be simulated well by the following equation: UFR = a.b.t/(1 + a.t) + c, where a, b, and c are constants and t is time. The effect of moisture adsorption onto the membrane on the UFR is discussed. A hypothesis is that in the amorphous region of cellulose, adsorbed water molecules would serve as molecular crosslinks through hydrogen bonding, and as this would reduce size of fine pores in the amorphous region, the UFR decreases.
Haemodialysers and Associated Devices
The principle of haemodialysis is simple. Blood and dialysis fluid are circulated on opposite sides of a semipermeable membrane which permits the passage of metabolites elevated as a consequence of renal failure but restricts the transfer of blood proteins and formed elements. The device containing the semi-permeable membrane is the haemodialyser. Removal of water occurs by control of the hydrostatic pressure gradient across the membrane and may be supplemented by increasing the dialysis fluid osmolality by the addition of glucose
Effects of reservoir volume on performance of pulse tube cooler.
A pulse tube cooler has the advantages of long-life and low-vibration over conventional cryocoolers such as G-M and Stirling coolers because of the absence of moving parts at low temperature. On the other hand, the combination of a reservoir and orifice is indispensable to optimize the performance of pulse tube coolers. In order to make the pulse tube cooler compact for practical applications, the volume of reservoir should be minimized. This paper analyzes the effects of the reservoir volume on the thermodynamic performance of various components in a simple orifice and a double-inlet pulse tube cooler by combining a linearized model with a thermodynamic analysis. Expressions of entropy production for those components are presented. The results show that the reservoir volume has a significant influence on the entropy production in the various components when the reservoir to pulse tube volume ratio is smaller than about 5. The ratio is important to determine the minimum reservoir volume for a pulse tube cooler. Optimum settings for a double-inlet pulse tube cooler are also discussed.