• 한국전기화학회:학술대회논문집
• /
• 한국전기화학회 2003년도 추계총회 및 학술발표회
• /
• pp.65-65
• /
• 2003

• 한국전기화학회:학술대회논문집
• /
• 한국전기화학회 2003년도 춘계총회 및 학술발표회
• /
• pp.57-57
• /
• 2003

• Membrane and Water Treatment
• /
• 제7권6호
• /
• pp.521-537
• /
• 2016

Laboratory-scale experiments were carried out to investigate the adsorption equilibrium, the adsorption kinetics and facilitated transport of two cationic dyes (Methylene Blue (MB) and Rhodamine B (RB)) on Polymer Inclusion Membrane (D2EHPA-PIM). Different adsorption isotherms (Freundlich, Langmuir and Temkin models) as well as kinetics models indicated that the adsorption process is spontaneous and exothermic. Under the optimal conditions, the adsorption removal efficiencies reach about 93% and 97% for MB and RB respectively. Different extraction values by D2EHPA-PIM were obtained for the two cationic dyes: MB is weakly extracted at pH 2.0 (E% = 18.7%) whilst E% = 82.4% was observed for RB at the same pH. This difference was exploited in a mixture containg both the 2 cationic dyes for the selective extraction of RB at pH 2. Desorption of both dyes was achieved from the membrane by using acidic aqueous solutions and desorption ratio up to 90% was obtained. The formulas of the extracted complexes by the PIMs were, determined by the method of slopes. The dyes transport was elucidated using mass transfer analysis where in it found relatively high values of the initial flux ($J_0$) as 41.57 and $18.74{\mu}mol.m^2.s^{-1}$ for MB and RB respectively.

• BMB Reports
• /
• 제39권4호
• /
• pp.394-399
• /
• 2006

The transport of putrescine into a moderately salt tolerant cyanobacterium Synechocystis sp. PCC 6803 was characterized by measuring the uptake of radioactively-labeled putrescine. Putrescine transport showed saturation kinetics with an apparent $K_m$ of $92{\pm}10\;{\mu}M$ and $V_{max}$ of $0.33{\pm}0.05\;nmol/min/mg$ protein. The transport of putrescine was pH-dependent with highest activity at pH 7.0. Strong inhibition of putrescine transport was caused by spermine and spermidine whereas only slight inhibition was observed by the addition of various amino acids. These results suggest that the transport system in Synechocystis sp. PCC 6803 is highly specific for polyamines. Putrescine transport is energy-dependent as evidenced by the inhibition by various metabolic inhibitors and ionophores. Slow growth was observed in cells grown under salt stress. Addition of low concentration of putrescine could restore growth almost to the level observed in the absence of salt stress. Upshift of the external osmolality generated by either NaCl or sorbitol caused an increased putrescine transport with an optimum 2-fold increase at 20 mosmol/kg. The stimulation of putrescine transport mediated by osmotic upshift was abolished in chloramphenicol-treated cells, suggesting possible involvement of an inducible transport system.

• Journal of Microbiology and Biotechnology
• /
• 제6권2호
• /
• pp.92-97
• /
• 1996

Portage kinetic constants of peptide transport can be measured by competitive spectrophotometry. The kinetic constants of L-Glu-L-Glu transport in Escherichia coli were ascertained using L-Phe-L-3-thia-Phe (PSP) as a detector. Since the production of thiophenol upon intracellular hydrolysis of PSP was competitively inhibited by L-Glu-L-Glu, it was able to compute the kinetic constants of L-Glu-L-Glu using this method. The resulted data were in agreement with the values obtained by the method of Michaelis-Menten kinetics. The potential of this method was examined against dipeptide transport systems in various microorganisms. These results strongly suggest that the overall properties of individual systems for dipeptide transports can be easily characterized by competitive spectrophotometry.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2000년도 춘계학술발표대회
• /
• pp.426-429
• /
• 2000

Recombinant E. coli JM109(pZH3-5/pMT) harboring manganese transport gene(mntA) and metal sequestering protein, metallothionein(MT), was cultivated to accumulate cadmium in aqueous phase. Bioaccumulation followed Michaelis-Menten type kinetics. Equilibrium isotherm showed Langmuir type isotherm. The optimum pH for $Cd^{2+}$ uptake was 7-7.5.

• 폴리머
• /
• 제39권2호
• /
• pp.268-274
• /
• 2015

In this paper, the isothermal crystallization kinetics of a functional PP (FPP) with different grafting yields (GY)-methacryloxyethyltrimethyl ammonium chloride (DMC) grafted PP were investigated by differential scanning calorimetry (DSC). The results showed that the crystallization rate of FPP (GY=4.83%) was the highest for all of the studied samples. Furthermore, for the FPP with different GY, the value of $t_{1/2}$ became longer with increasing the grafting yield (GY). The possible explanation was that the quaternary ammonium groups introduced affected the crystallization process of the FPP in two opposite directions, i.e. promoting the nucleation and hindering the transport of the chain molecules towards the growing nuclei. Polarized optical micrographs showed that the DMC chains acted as nucleating agents, which accelerated the nucleation. In addition, the results showed the FPP had lower nucleation free energy than the PP. This study would be useful for designing the processing parameters of the grafted samples.

• Computers and Concrete
• /
• 제2권1호
• /
• pp.19-30
• /
• 2005

We study the kinetics of absorption of water in Portland cement concretes added with 60, 70 and 80% of granulated blast furnace slag (GGBS) cured in water and at open air and preheated at 50 and $100^{\circ}C$. A mathematical model is presented that allows describing the process not only in early ages where the capillary sorption is predominant but also for later and long times where the diffusive processes through the finer and gel pores are considered. The fitting of the model by computerized methods enables us to determine the parameters that characterize the process: i.e., the sorptivity coefficient (S) and diffusion coefficient (D). This allows the description of the process for all times and offers the possibility to know the contributions of both, the diffusive and capillary processes. The results show the influence of the curing regime and the preheating temperature on the behavior of GGBS mortars.

• 한국토양비료학회지
• /
• 제44권1호
• /
• pp.84-90
• /
• 2011

It is imperative to study the hydrolysis of urea in high saline-sodic condition of a newly reclaimed tidal land in order to overcome the problems associated with use of urea fertilizer. The methodology adopted in this study tried to get a convenient way of estimating rate for N transformation needed in N fate and transport studies by reviewing pH and salt contents which can affect the microbial activity which is closely related to the rate of urea hydrolysis. The hydrolysis of urea over time follows first-order kinetics and soil urease activity in reclaimed soils will be represented by Michaelis-Menten-type kinetics. However, high pH and less microorganisms may delay the hydrolysis of urea due to decrease in urease activity with increasing pH. Therefore, the rate of urea hydrolysis should adopt $V_{max}$ referring enzyme activity ($E_0$) accounting for urease concentration which is indicative for urea hydrolysis, especially in a high saline and sodic soils.

• 한국물환경학회지
• /
• 제40권4호
• /
• pp.179-194
• /
• 2024

Biophysicochemical processes in water environments and treatment systems have been great concerns of engineers and scientists for controlling the fate and transport of contaminants. These processes are practically formulated as mathematical models written in coupled differential equations. However, because these process-based mathematical models consist of a large number of model parameters, they are complicated in analytical or numerical computation. Users need to perform substantial trials and errors to achieve the best-fit simulation to measurements, relying on arbitrary selection of fitting parameters. Therefore, this study adopted a Bayesian calibration method to estimate best-fit model parameters in a systematic way and evaluated the applicability of the calibration method to biophysicochemical processes of water environments and treatment systems. The Bayesian calibration method was applied to the microbial growth-decay kinetics and flocculation kinetics, of which experimental data were obtained with batch kinetic experiments. The Bayesian calibration method was proven to be a reasonable, effective way for best-fit parameter estimation, demonstrating not only high-quality fitness, but also sensitivity of each parameter and correlation between different parameters. This state-of-the-art method will eventually help scientists and engineers to use complex process-based mathematical models consisting of various biophysicochemical processes.