Urea, Creatinine and Phosphate Kinetic Modeling during Dialysis: Application to Pediatric Hemodialysis

1995 ◽  
Vol 18 (3) ◽  
pp. 122-129 ◽  
Author(s):  
M. Maasrani ◽  
M.Y. Jaffrin ◽  
M. Fischbach ◽  
B. Boudailliez
Keyword(s):  
Mass Transfer ◽  
Pediatric Patients ◽  
Large Time ◽  
Phosphate Removal ◽  
Transfer Coefficients ◽  
Pediatric Hemodialysis ◽  
Fluid Shifts ◽  
Pool Model ◽  
Kinetics Of ◽  
Phosphate Influx

The kinetics of urea, creatinine and phosphate removal during dialysis were investigated in pediatric patients using a two-pool model taking into account fluid shifts and mass transfer between the two compartments. It is found that even urea must be described by a two-pool model since it presents a post dialysis rebound due to equilibration between the two compartments. Phosphate plasma concentration drops very sharply during the first hour of dialysis and rises rapidly during the rebound period. This pattern cannot be accounted for by the classical two-pool model with constant generation rate and mass transfer coefficients, but corresponds to a large time-dependent phosphate influx from the intracellular compartment in which phosphate is generated by biochemical reactions or liberated from the bones. This influx was calculated for four patients representing 8 dialysis sessions and was found to reach a plateau after 90 minutes of dialysis, dropping rapidly during the rebound period.

Kinetics of the Heterogeneous Ozonation of Nitrated Phenols

1992 ◽  
Vol 26 (1-2) ◽  
pp. 169-180 ◽  
Author(s):  
J. P. Gould ◽  
G. V. Ulirsch
Keyword(s):  
Mass Transfer ◽  
Rate Constants ◽  
Chemical Structure ◽  
Process Analysis ◽  
Qsar Model ◽  
Zero Order ◽  
Transfer Coefficients ◽  
First Order ◽  
Kinetics Of ◽  
Phenolic Concentration

The kinetics of the heterogeneous ozonation of phenol and 27 nitrophenols representing a wide array of functional groups have been studied. In the systems examined, the process has been found to be zero order with respect to phenolic concentration which indicates mass transfer as the prime control on the process. Analysis of the first order rate constants has permitted computation of overall mass transfer coefficients for all compounds. The coefficients were sixty percent lower than the kLa values measured by others in water and showed very little variation regardless of chemical structure of the phenol. Efforts at development of a QSAR model for the kinetics were fruitless.

Elimination of Aluminum During the Process of Ti-6Al-4V Alloy, Smelting in a Vacuum Induction Furnace / Eliminacja Aluminium W Procesie Wytopu Stopu Ti-6Al-4V W Indukcyjnym Piecu Próżniowym

2012 ◽  
Vol 57 (4) ◽  
pp. 951-956 ◽  
Author(s):  
G. Siwiec
Keyword(s):  
Mass Transfer ◽  
Liquid Alloy ◽  
Pressure Range ◽  
Induction Furnace ◽  
Aluminum Concentration ◽  
Vacuum Induction Furnace ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Kinetics Of

In the paper, results of the study on kinetics of aluminum evaporation from a liquid Ti-6Al-4V alloy during its smelting in a vacuum induction furnace are presented. The experiments were performed with the use of a VIM 20-50 furnace (manufactured by SECO-WARWICK) at 1973 K and 5-1000 Pa. Based on the values of changes in aluminum concentration in a liquid alloy, overall mass transfer coefficients were estimated. Within the analysed pressure range, the coefficient values changed from 0.97·10-5 ms-1 to 1.93·10-5 ms-1 for 1000 Pa and 5 Pa, respectively

scholarly journals Extraction of Clove and Vetiver Oils with Supercritical Carbon Dioxide: Modeling and Simulation

2007 ◽  
Vol 1 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Julian Martínez ◽  
Paulo T.V. Rosa ◽  
M. Angela A. Meireles
Keyword(s):  
Carbon Dioxide ◽  
Mass Transfer ◽  
Large Scale ◽  
Raw Material ◽  
Feed Ratio ◽  
Transfer Model ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Extraction Curve ◽  
Kinetics Of

The kinetics of supercritical fluid extraction (SFE) of clove and vetiver oils using carbon dioxide as solvent was studied, in order to establish an efficient method to predict extraction curves on large scale. The mass transfer model of Sovová was used to adjust the experimental SFE data, which were obtained at 100 bar and 35 °C for clove and 200 bar and 40 °C for vetiver, using extraction columns of different geometry and solvent flow rates. Some other process parameters, such as bed density and porosity, solvent to feed ratio and solvent velocity were kept constant from one experiment to another, in order to verify if the mass transfer coefficients adjusted by the model varied. The results show that the model of Sovová was able to predict an overall extraction curve for clove from data obtained with twenty times less raw material, since the mass transfer coefficients remained the same and the predicted curves were similar to the observed ones. For vetiver, the simulation was not as effective, probably due to the effects of transport properties on the process.

scholarly journals Modelling the Mass Transfer Kinetics of Battered and Breaded Fish Nuggets during Deep-Fat Frying at Different Frying Temperatures

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Wei Zhang ◽  
Jiwang Chen ◽  
Yi Yue ◽  
Zhenzhou Zhu ◽  
E Liao ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Moisture Loss ◽  
Order Kinetic ◽  
Fat Absorption ◽  
Transfer Coefficients ◽  
Frying Temperature ◽  
Mass Transfer Kinetics ◽  
Order Kinetic Model ◽  
Different Temperatures ◽  
Kinetics Of

Battered and breaded fish nuggets (BBFNs) were fried at three different temperatures (160, 170, and 180°C) for 30–180 s to study the mass transfer kinetics of moisture loss and fat absorption. The mass transfer mechanism was investigated through an analysis of microstructure, surface oil (SO), and penetrated surface oil (PSO) contents of fried BBFNs. The results showed that Fick’s second law of diffusion and the first-order kinetic model could well describe the kinetics of moisture loss and fat absorption of the crust, respectively. Transfer coefficients of the two mass transports significantly increased with an increase in the frying temperature ( P < 0.05 ). With the increase in the frying temperature, pore size of the crust increased. The PSO content of the crust also increased with elevated frying temperature. These results suggest that frying temperature affects the moisture loss and fat absorption kinetics of the crust by changing its microstructure.

Modeling mass transfer and substrate utilization in the boundary layer of biofilm systems

1998 ◽  
Vol 37 (4-5) ◽  
pp. 139-147 ◽  
Author(s):  
Harald Horn ◽  
Dietmar C. Hempel
Keyword(s):  
Boundary Layer ◽  
Mass Transfer ◽  
Reynolds Number ◽  
Film Theory ◽  
Substrate Utilization ◽  
The Other ◽  
Concentration Profiles ◽  
Hydrodynamic Conditions ◽  
Time Axis ◽  
Transfer Coefficients

The use of microelectrodes in biofilm research allows a better understanding of intrinsic biofilm processes. Little is known about mass transfer and substrate utilization in the boundary layer of biofilm systems. One possible description of mass transfer can be obtained by mass transfer coefficients, both on the basis of the stagnant film theory or with the Sherwood number. This approach is rather formal and not quite correct when the heterogeneity of the biofilm surface structure is taken into account. It could be shown that substrate loading is a major factor in the description of the development of the density. On the other hand, the time axis is an important factor which has to be considered when concentration profiles in biofilm systems are discussed. Finally, hydrodynamic conditions become important for the development of the biofilm surface when the Reynolds number increases above the range of 3000-4000.

Henry's constants and mass transfer coefficients of halogenated organic pollutants in an air stripping packed column

1998 ◽  
Vol 38 (6) ◽  
pp. 287-294 ◽  
Author(s):  
Pen-C. Chiang ◽  
Chung-H. Hung ◽  
J. C. Mar ◽  
E. E. Chang
Keyword(s):  
Mass Transfer ◽  
Methylene Chloride ◽  
Packed Column ◽  
Transfer Coefficients ◽  
Chlorinated Organic Compounds ◽  
Air Stripping ◽  
Mass Transfer Coefficients ◽  
Equilibrium Partition ◽  
Henry's Constants ◽  
Chlorinated Organic

Both Henry's constants and volumetric mass transfer coefficients (KLa) of eight priority chlorinated organic compounds including 1,1-dichloroethene, methylene chloride, chloroform, carbon tetrachloride, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethylene, and 1,4-dichlorobenzene in an air stripping packed column were investigated in this study. The liquid and gas phase EPICS (Equilibrium Partition in Closed System) and direct calculating methods were applied to determine the Henry's constants of VOCs. The interference of co-solute on Henry's constants was also investigated. Experimental results indicated that decrease in Henry's constants of VOCs was observed in the presence of humic acid but no apparent effect on Henry's constants was detected when there was NaCl and surfactant in solution. Four different configurations of packing media including Intalox Saddle, Super Intalox Saddle, Telleret, and Hedgehog made of polypropylene were respectively packed in the air stripping tower and investigated in the study. The dependence of hydraulic loading, air-water ratio, and configurations of packing media on mass transfer coefficients of VOCs was discussed.

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