Fumitake Yoshida

Rates of absorption of oxygen into blood under turbulent conditions

Abstract Oxygen was absorbed into deoxygenated blood and hemoglobin solutions, and also into blood and hemoglobin solutions in which the hemoglobin was saturated with oxygen or inactivated with carbon monoxide, through an artificial membrane attached to the bottom of an agitated vessel containing the blood or solutions. From a comparison of the rates of physical absorption of oxygen into saturated or inactivated blood and hemoglobin solutions with those into water and sodium chloride solutions in the same vessel, the effective diffusivity of oxygen through the saturated or inactivated blood was obtained as a function of hematocrit. Data on the rates of oxygen absorption into deoxygenated blood and hemoglobin solutions were analyzed on the basis of the turbulent boundary layer model for mass transfer with chemical reaction.

Ultrafiltration of blood: effect of hematocrit on ultrafiltration rate.

Rates of ultrafiltration of bovine blood of various hematocrits were measured in ultrafilters of hollow-fiber type. The results were analyzed by the gel-polarization model. The mass transfer coefficientk for the back-diffusion of protein molecules away from the gel layer, which controls the ultrafiltrate flux, increase with the cube root of the shear rate at the membrane surface. At a given shear rate, it increases and then decreases with increasing hematocrit. A working equation for predictingk is proposed.

Aeration and Mixing in Fermentation

Publisher Summary This chapter discusses aeration and mixing in fermentation. The purpose of aeration in fermentation is to supply oxygen to and, at the same time, to remove carbon dioxide from microbial cells suspended in the culture broth. The rate of aeration often controls the rates of cell growth and product formation. Mixing in the gas and liquid phases affects the aeration characteristics of a fermentor. Various types of aerobic fermentors could be classified into three major types: (1) sparged mechanically stirred fermentor, (2) bubble column fermentor, and (3) loop fermentor. In the sparged stirred fermentor, gas, usually air, is sparged into the broth, which is mechanically agitated. Fermentors of this type are still used most widely for various aerobic fermentations. The bubble column is a cylindrical vessel containing a liquid through which gas is bubbled; this can be operated continuously with either counter- or co-current flows of liquid or gas. In the loop fermentor, liquid is recirculated by the difference of the average densities of the broth between the gassed and ungassed sections or by means of a pump or fluid jet. All of these three major types and combinations thereof have various modifications.

Biochemical Engineering: A Textbook for Engineers, Chemists and Biologists

The central theme of the textbook remains the application of chemical engineering principles to biological processes in general, demonstrating how a chemical engineer would address and solve problems. To create a logical and clear structure, the book is divided into three parts. The first deals with the basic concepts and principles of chemical engineering and can be read by those students with no prior knowledge of chemical engineering. The second part focuses on process aspects, such as heat and mass transfer, bioreactors, and separation methods. Finally, the third section describes practical aspects, including medical device production, downstream operations, and fermenter engineering. More than 40 exemplary solved exercises facilitate understanding of the complex engineering background, while self-study is supported by the inclusion of over 80 exercises at the end of each chapter, which are supplemented by the corresponding solutions.

Carbon dioxide transfer in a membrane blood oxygenator.

Rates of desorption of CO2 from bovine blood, as well as bovine serum, aqueous hemoglobin solutions, and water in a flat-plate-type experimental membrane blood oxygenator using silicone rubber and microporous polypropylene membranes were measured. The experimental data showed good agreement with the rigorous theoretical predictions based on an assumption that the CO2 transfer in the liquid phase is facilitated by simultaneous diffusion of bicarbonate ions produced by the instantaneous hydration of CO2 catalyzed by carbonic anhydrase existing in the red cells. Effects of screen turbulence promoters in the liquid channel were also studied. The overall resistance for CO2 transfer in membrane oxygenators including the blood phase resistance is usually smaller than that for oxygen transfer, unless the liquid phase mass transfer resistance is small relative to the membrane resistance. Thus, a membrane oxygenator designed on the basis of oxygen transfer rates will almost always have a sufficient capacity for CO2 transfer.

Rate of blood oxygenation in a flat plate membrane oxygenator

Abstract Rates of oxygen absorption into deoxygenated blood and hemoglobin solutions as well as into water and serum have been measured in a flat plate membrane oxygenator. The experimental results on the physical absorption of oxygen agree with the calculation using the equation of Grimsrud and Babb, and the data on oxygen absorption into deoxygenated blood and hemoglobin solutions show good agreement with the prediction based on the numerical soution of a differential equation with the assumptions of instantaneous equilibrium of the oxygen—hemoglobin reaction and Newtonian behavior of the blood. The data show fairly good agreement with the approximate calculation method of Lightfoot.

Physical factors affecting microembolus formation in extracorporeal circulation.

Rates of microembolus formation in oxalated and heparinized blood in an agitated vessel, a bubble column, and a rotating disk gas-liquid contactor were studied by measuring the pressure required to filter the blood sample through a screen with a mesh size of 37 μm and the dry weight of microemboli retained on the screen. The rate of microembolus formation increased with the blood-gas contact area and the rate of surface renewal. Although the results are rather qualitative, the contribution of turbulence in blood seems relatively unimportant.

Treatment of artificial kidney dialysate with cycling adsorber-desorbers

A new hemodialyzing system is proposed in which urea and other toxins are removed from the recirculating dialysate by adsorption on activated carbon in two alternately used adsorber-desorber columns. Desorption of urea and other molecules was performed by passing water and then fresh dialysate through the adsorbent bed. Durations of the periods for adsorption and desorption could be varied using a timer and solenoid valves.In vitro experiments showed sufficient decrease in the concentrations of ureaet al. in the body fluid, while their concentrations in the recycling dialysate stayed very low. The adsorbent can be used repeatedly after regeneration. The new system is considerably more economical than the conventional hemodialyzing system with continuous dilution of dialysate in the cost of construction and the amount of dialysate required.