It is examined whether the principle of reflectometry, developed to measure the thickness of a thin layer on a surface, is applicable to detecting quantitatively the amount of fine particles deposited on a substrate. It is found that the relative difference of parallel and perpendicular components of the laser beam reflected on the surface is proportional to the particle coverage if experimental conditions are suitably selected, and that this principle is able to be used to detect with high sensitivity in-situ the amount of particles.
The lateral and axial mixing of dispersed particles in a circulating fluidized bed were measured by using the phosphor tracer technique. The measured residence time distribution was satisfactorily described by a proposed two dimensional plug flow dispersion flow. Compared with that in the cocurrent downflow circulating fluidized bed (CDCFB), the dispersion Peclet numbers for lateral and axial mixing of dispersed particles is about the same value with that in CDCFB (downer). Correlations of the Peclet numbers under the operating conditions are presented.
The extraction equilibrium of samarium (Sm) with diisostearylphosphoric acid (DISPA, HR) was measured at 303 K. The complex, SmR3, was formed, unlike in the case of dialkylphosphoric acids investigated previously. The extraction rate of Sm with DISPA was measured using a stirred transfer cell. The extraction rates were limited by the diffusion process. The permeation of samarium through a supported liquid membrane containing DISPA as a carrier was carried out based on the above results. Under the experimental conditions, the diffusion of samarium in the film of the aqueous feed or the diffusion of the complex in the membrane phase was anticipated to be the rate-determining step.
The initial rates of ATP regeneration catalyzed by acetate kinase (ATP: acetate phosphotransferase; EC 18.104.22.168) from Bacillus stearothermophilus were measured under a wide range of MgADP–, acetyl phosphate, MgATP2– and acetate concentrations. The experimental results showed that the enzyme exhibited positive co-operativity for MgATP2– and no co-operativity for MgADP–, acetyl phosphate and acetate. Furthermore, the initial rates of the forward reaction, in which MgATP2– and acetate were produced from MgADP– and acetyl phosphate, were inhibited by MgATP2– and acetate, and those of the reverse reaction were inhibited by MgADP– and acetyl phosphate. The initial rate data were correlated well by using the rate equation derived based on the assumption that the reaction obeys the general reaction scheme based on the Random Bi Bi mechanism, and on the previous experimental result that the enzyme behaves like a dimeric enzyme, even though it is a tetrameric enzyme.
A continuous-flow fluidized-bed bioreactor system containing porous carrier particles was operated for simultaneous removal of carbonaceous and nitrogenous substances from wastewaster. The bioreactor system consisted of two aerobic reactors in series with recycle-flow. Organic oxidation, ammonification of urea and nitrification took place in both reactors, while denitrification concurrent with those reactions occurred in the reactor where the artificial sewage and recycled fluid were fed. In the steady state, measurement of microbial activities in the reactors confirmed the presence of the respective bacteria participating in the above reactions. These multiple reactions proceeded simultaneously in the bioreactor system were analyzed by a set of simple reaction kinetics, which interpreted the experimental results well.
In order to understand the filtration mechanism in microfiltration, information concerning cake concentration is important because the cake reduces the permeation rate. In this work, an ultrasonic measurement method of local cake concentration on the microriltration membrane was developed by using a special array polymer transducer. This method was applied to microliltration both with suspensions of yeast and polystyrene particles to study the effect of solidity of solute on cake compression. As a result, it was found that the yeast cake was compressible but that of polystyrene particles incompressible.
The transport velocity of a coarse particle in a Multi-Solid Fluidized Bed (MSFB) consisting of particles different in size and density was measured using an acoustic technique. Effects of the solid circulating rate of fine particles on the diameter of coarse particles were studied. The equation for calculating the transport velocity was established considering the collision characteristics between the fine and coarse particles. The transport velocity of coarse particles obtained by solving the related equation demonstrated a good agreement with those obtained from the experimental data. The calculated results for air-fine 50 mm and 100 mm particles coincided with the experimental results within 20% and 34% errors, respectively. Experimental results obtained in a lab-scale MSFB with a diameter of 0.05 m showed that the transport velocity of coarse particles decreased with increasing the solid circulation rate.
The design challange in multipurpose batch plants is optimizing plant configuration and equipment size under the constraints of multiple production plans, and these decision variables are interactive with each other through scheduling. To optimize these decision variables, the evolutionary design method on the basis of scheduling according to cyclic production (cyclic scheduling) is appropriate, and batch composition of a cycle (number of batches and their relative batch sizes per one-cycle) for respective production plans should be specified beforehand. In this study, a method to specify the batch composition that enables optimal design is developed. From the viewpoint of optimizing plant configuration, the common batch sizes for a multiple number of production plans (core batch sizes) are introduced for each product, and specifying the batch composition on the basis of these core batch sizes is converted into assignment problems, from the viewpoint of optimizing equipment sizes. These assignment problems are formulated into IP (Integer Programming) models, and the optimal design satisfying multiple production plans becomes possible. The effectiveness of this method is demonstrated through an example problem.
The deactivation kinetics of yeast alcohol dehydrogenase (YADH) in both aerosol OT/isooctane reverse micelles and aqueous buffer were studied. The YADH entrapped in reverse micelles; could retain activity for above 24 hr although it was less stable than dissolved in aqueous buffer. Both the activity-time curves for the YADH in reverse micelles and in aqueous buffer exhibited a rather rapid exponential decay within the early 2 hr, followed by a slower exponential decay during the remaining period. A series-type enzyme deactivation model involving two first-order steps and one active intermediate was used to describe the deactivation behavior of YADH. The kinetic parameters of the deactivation rate equations were obtained by optimization method. In aqueous buffer, the deactivation rate of YADH exhibited a maximum around a Tris concentration of 0.1 mol·m–1. The deactivation rate of YADH in reverse micelles was strongly dependent on Tris concentration and the molar ratio of water to surfactant (ωo). The residual activity percentage of the active intermediate increased with the increase of ωo and Tris concentration, while both the rate constants for the first and second first-order deactivation steps decreased with the increase of Tris concentration.
The effects of magnesium oxide (MgO), calcium oxide (CaO), and zinc oxide (ZnO) powder slurries on spores of Bacillus subtilis were examined. The CaO and MgO powder slurries were able to kill the spores of B. subtilis in physiological saline. The efficacy of the CaO powder slurry was much higher than that of the MgO powder slurry. It was considered that the efficacy of the CaO powder slurry against the spores depended on effects of Ca2+ and some factors due to contact between spores and the CaO powders. When the spores and nutrients such as growth medium existed together, it was observed that the MgO, CaO and ZnO powder slurries exhibited antibacterial activity against spores of B. subtilis. There was no difference in sensitivity to the ceramic powder slurry between the vegetative cells and the spores of B. subtilis. Further, the supernatant of the ceramic powder slurries promoted the germination of the spores. Therefore, it was suggested that the ceramic powder slurries weakened a high dormancy of spores, and acted on the germinated spores.
In order to provide a quantitative basis to discuss the efficiency of purification of organic mixtures achieved by layer or suspension type melt crystallization operations, experiments of purification by sweating were carried out with naphthalene-benzothiophene solid solution mixtures. The rate and the degree of composition changes were analyzed for crude crystals prepared either as a layer on a cold surface or as a suspension in a supercooled melt. The purification by sweating was conducted at constant temperatures (isothermal sweating) and the rate of composition change was evaluated by the purification rate coefficient kp, which was defined as the ratio of the purification rate to the excess amount of the impurity in the crude crystal phase. The values of the purification rate coefficient for the layer type were found to be always lower than those for the suspension type, while the amount of impurities unable to be removed by sweating from the layer was larger than that for the suspension crystals. Consequently, it is concluded that purification by isothermal sweating in terms of the rate and the attainable purity was higher for the suspension type than the layer one in the present experiments. These results and the significance of the purification rate coefficient were discussed quantitatively.
This study is concerned with enhancing the heat transfer rate in a falling film layer of ethylene glycol on an inclined rectangular tray by applying ultrasonic waves irradiated from the bottom of the tray. The heat transfer coefficient in a falling film layer of ethylene glycol was determined by the measured temperature distributions under various conditions of liquid flow rate, power supplied to an ultrasonic vibrator and frequency of the ultrasonic wave. The evaporation rate of water from a failing film of ethylene glycol/water mixture was also measured. As a result, the enhancing effect of ultrasonic irradiation on the heat transfer coefficient was obtained with increasing liquid flow rate. It was found that ultrasonic irradiation of 23.6 kHz was more effective to enhance the heat transfer rate in a falling film layer than 46.9 kHz ultrasonic waves. The heat transfer coefficient in a falling film layer was increased by ultrasonic irradiation in the order about 30%, which was obtained at a film Reynolds number of 50.0 by using 23.6 kHz ultrasonic waves. It was recognized that ultrasonic waves increased the evaporation rate of water in a falling film of ethylene glycol/water mixture.
A stagewise algorithm is proposed for the solution of multicomponent multistage batch distillation problems. In order to make the algorithm more precise and flexible, a generalized implicit Euler equation is implemented for numerical integration of the process variables on each stage at succeeding time steps. An overall normalized θ method is also employed to accelerate convergence for each time step. The relative performance of the proposed method compared with the Runge-Kutta method is shown using a numerical example; the CPU time can be decreased by up to 1/300. Comparison of the simulation results with the experiment suggests the adequacy of the proposed method.
As a study on the extraction apparatus for separation and purification of proteins and other molecules using reversed micellar systems, the mean drop diameter and drop size distribution of the reversed micellar dispersed phase have been investigated using a rotating disc contactor (RDC) of 38 mm diameter. The Sauter mean diameter was correlated with the Reynolds number, Re, the Weber number, We and the density ratio of the two phases, and the correlation was found to be in good agreement with the experimental data within 15%. The data obtained from the experimental runs and the correlation are compared with those of other authors for liquid-liquid systems without surfactants. The Mugele-Evans distribution function has proved to be the best of the four functions of Mugele-Evans, log-normal, normal and Weibull distribution functions for representing the experimental drop size distribution data. Correlations for the distribution function parameters by means of the Sauter mean diameter obtained in this work can be used to estimate drop size distribution of the reversed micellar systems.
Attachment kinetics of BHK cells in very short contact times (0, 1, 2, 3 and 5 min) under static conditions was investigated on tissue-culture-treated polystyrene (TC-PS) dishes preadsorbed with various proteins. Although cells attached rapidly onto bare TC-PS, they did not attach at all within 1–2 min of contact when the surfaces were preadsorbed with serum albumin (Alb), even at low surface coverage. The specific interaction between adsorbed fibronectin (FN) and cells required a short contact time to accomplish the attachment. Moreover, FN adsorption at low surface coverage retarded the cell attachment up to 2 min as compared to the bare TC-PS. These inhibitory effects of FN were completely overcome by postcoating with polylysine (PL), which did not inhibit the spreading promoting activity of FN. Both Alb and FN adsorption had some contributions in enhancing the surface hydrophobicity, whereas post-treatment of the FN adsorbed surfaces by PL did not change the characteristics at all. Having considered that Alb and FN themselves are negatively charged at physiological pH, cell contact and attachment initiation onto solid surfaces once preadsorbed with proteins were strongly suggested to be predominated by electrostatic interactions simply by evaluating the charge sign of adsorbed proteins.
Bubble columns are frequently used in the chemical industry as absorbers, fermenters and reactors. Recently bubble columns have been used as bio-reactors for non-Newtonian liquids. Thus, experiments were performed to investigate the size of bubbles generated from a perforated plate in a non-Newtonian liquid. The bubble size distribution may follow a logarithmic normal probability distribution despite the plate geometry and physical properties of the liquids. The characteristic correlation for the size of bubbles generated from the perforated plates in non-Newtonian liquids was derived.
Equilibrium and non-equilibrium extraction separations of rare earth metals were carried out in the presence of chelating agent in the aqueous phase. The separation systems of the rare earth metal mixtures used were Y/Dy, Y/Ho, Y/Er and Y/Tm, and the chelating agent and the extractant were diethylenetriaminepentaacetic acid (DTPA) and bis(2,4,4-trimethylpentyl) phosphinic acid (CYANEXR® 272), respectively. For Y/Dy and Y/Ho systems, higher selectivities were obtained in equilibrium separation compared with those in non-equilibrium separation. On the other hand, the selectivities in non-equilibrium separation were higher for Y/Er and Y/Tm systems. In the separation condition suitable to each system, the addition of DTPA to the aqueous phase was found to be very effective for obtaining higher selectivities. The distribution ratios of the rare earth metals and the selectivities in the equilibrium separations obtained experimentally were thoroughly analyzed by considering various equilibria such as the extraction equilibrium and the complex formation equilibrium between rare earth metals and DTPA in the aqueous phase. Moreover, the extraction rates and the selectivities in the non-equilibrium separations were also analyzed by the extraction model considering the dissociation reactions of the rare earth metal-DTPA complexes in the aqueous stagnant layer. Based on these analyses, we presented an index which is useful for selecting the optimum operation mode, that is, for determining whether equilibrium or non-equilibrium separation should be employed. Using this index, we can predict that the selectivities under equilibrium conditions are higher than those under non-equilibrium conditions for Y/Dy and Y/Ho systems, while for Y/Er and Y/Tm systems, higher selectivities are obtained under non-equilibrium conditions. The experimental results were in agreement with predictions by this index. Further, the selectivities in various systems including other chelating agents and extractants were discussed based on this index.