• Journal of Pharmaceutical Investigation
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• v.23 no.3
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• pp.1-8
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• 1993

A simple and quick method based on the transient diffusion theory for predicting the steady state rate of penetration of a drug after transdermal drug administration was proposed. The amount of drug entering the stratum corneum was determined by 20 strippings with an adhesive tape. From the profile of the amount of drug as a function of the number of strippings, the quantity of drug on the surface of stratum corneum was extrapolated. Based on the amounts of drug entering the stratum corneum during two time intervals $(t_1\;and\;t_2)$ within 1 hour after the application, the diffusion and partition coefficient were determined. Once the diffusion coefficient of the drug in the stratum corneum and the partition coefficient (stratum corneum/vehicle) were determined from the present approach, the steady-state flux of penetration across the stratum corneum was calculated. The steady-state rates of penetration of ascorbic acid and estradiol across hairless mouse skin were evaluated from this approach and compared with those obtained from ill vitro penetration experiment using excised hairless mouse skin. The data confirmed that the proposed method can predict the steady-state rate of penetration of these drugs across the stratum corneum.

• Journal of Environmental Health Sciences
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• v.34 no.3
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• pp.219-225
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• 2008

Many building materials may contain high concentrations of volatile organic compounds (VOCs) and other hazardous pollutants(HAPs). Specifically, VOCs discharged by indoor building material may cause "new house" syndrome, atopic dermatitis etc. The diffusion coefficient and initially contained total VOC quantity were determined using microbalance experiments and small chamber tests. Interactions between volatile organic compounds (VOCs) and vinyl flooring (VF), a relatively homogenous, diffusion-controlled building material, were characterized. Rapid determination of the material/air partition coefficient (K) and the material-phase diffusion coefficient (D) for each VOC was achieved by placing thin VF slabs in a dynamic microbalance and subjecting them to controlled sorption/desorption cycles. K and D are shown to be independent of concentration for all of the VOCs and water vapor. This approach can be applied to other diffusion-controlled materials and should facilitate the prediction of their source/sink behavior using physically-based models.

• Archives of Pharmacal Research
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• v.10 no.2
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• pp.88-93
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• 1987

Chitosan ($\beta$-D-glucosaminan) is chemically prepared from chitin (N-acetyl-$\beta$- D-glucosaminan) which is an unutilized natural resource. We now report on the suitability of the chitosan matrix for use as vehicles for the controlled release of drugs. Salicylic acid and aspirin were used as model drugs in this study. The permeation of salicylic acid in the chitosan membranes was determined in a glass diffusion cell with two compartments of equal volume. Drug release studies on the devices were conducted in a beaker containing 5% sodium hydroxide solution. Partition coefficient (Kd) value for acetate membrane (472) is much greater than that for fluoro-perchlorate chitosan membrane (282). Higher Kd value for acetate chitosan membrane appears to be inconsisstent with the bulk salicylic acid concentration. The permeability constants of fluoro-perchlorate and acetate chisotan membranes for salicylic acid were 3.139 ${\times}10^{-7}cm^2$ min up to 60 min and that of 30% aspirin in the devices was 4.739${\times}10^{-7}cm^2$sec upto 60 min. As the loading dose of aspirin in a chitosan device increased, water up-take of chitosan device increased, but in case of salicylic acid it decreased. The release rate increased with increase in the molecular volume of the drugs. Thses result suggest that the release mechanism may be controlled mainly by diffusion through pores.

• KSBB Journal
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• v.8 no.2
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• pp.178-184
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• 1993

Extractive fermentations with the extract of Jerusalem artichoke in an aqueous-two-phase-system of polyethyleneglycol(PEG) and dextran(Dx) were investigated to obtain the effects of composition of PEG and Dx on both fermentation ,characteristics and partition ratio of alcohol. The specific growth rate of K. Fraglis CBS 1555 increased with a decrease of concentration of PEG and Dx. It augmented along with concentration of initial sugar up to 80g/l but decreased thereafter. The specific production rate of alcohol showed a rising tendency up to 100g/lof initial sugar, whereafter represented a decreasing trend. The partition ratio of alcohol between two phases augmented according to decrease of Dx comic. and increase of PEG cone. regardless of initial sugar concentrations. The ratio, however, decreased with Increment of initial sugar concentration at constant composition of PEG and Dx. The partition coefficient of alcohol had an ascending effect to the increase of PEG cone, but it had little effect on the changes of concentrations of Dx and initial sugar. The present study suggests that the optimum composition of PEG and Dx in the aqueous-two-phase-system by extractive fermentation were around 6.5%(w/v) of PEG and 3%(w/v) of Dx in considerations of emulsion state, sedimentation and separation of two phases, alcohol partition ratio, and specific growth rate.

• Nuclear Engineering and Technology
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• v.54 no.4
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• pp.1495-1507
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• 2022

The improvement of thermal-hydraulic analysis techniques is essential to ensure the safety and reliability of nuclear power plants. The one-dimensional two-fluid model has been adopted in state-of-the-art thermal-hydraulic system codes. Current constitutive equations used in the system codes reach a mature level. Some exceptions are the partition method of wall friction in the momentum equation of the two-fluid model and the interfacial drag force model for a horizontal two-phase flow. This study is focused on deriving the partition method of wall friction in the momentum equation of the two-fluid model and modeling the interfacial drag force model for a horizontal bubbly flow. The one-dimensional momentum equation in the two-fluid model is derived from the local momentum equation. The derived one-dimensional momentum equation demonstrates that total wall friction should be apportioned to gas and liquid phases based on the phasic volume fraction, which is the same as that used in the SPACE code. The constitutive equations for the interfacial drag force are also identified. Based on the assessments, the Rassame-Hibiki correlation, Hibiki-Ishii correlation, Ishii-Zuber correlation, and Rassame-Hibiki correlation are recommended for computing the distribution parameter, interfacial area concentration, drag coefficient, and relative velocity covariance of a horizontal bubbly flow, respectively.

• Journal of Soil and Groundwater Environment
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• v.12 no.2
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• pp.47-54
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• 2007

The partitioning tracer method has been studied as an alternative method for detecting and characterizing the distribution of nonaqueous phase liquids (NAPLs) contaminants in subsurface. The reliability of the partitioning tracer method depends on accurate measurements of partition coefficients of the partitioning tracers between water and NAPLs. In this study, partition coefficients of several alcohol tracers between water and benzene, toluene, ethylbenzene, xylene, and BTEX mixtures are estimated using the modified approach of equivalent alkane carbon number (EACN). Agreements between the measured and estimated partition coefficients were generally observed in experiments. Based on these results, it is confirmed that the partition coefficients of tracers are readily obtained without experiments if the EACN values for the tracers and LNAPLs are known.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.4
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• pp.200-209
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• 2003

Distribution coefficient ($K_d$) is an universal parameter estimating cadmium partition for a soil-water-crop system in agricultural lands. This study was performed to find some factors affecting soil-water partition coefficients for cadmium in some Korean soils. The distribution coefficients ($K_d$) of cadmium for the 15 series of agricultural soils were measured at quasi-steady state in the pH ranges from 2 to 11. The adsorption data of the selected soils showed a linear relationship between log $K_d$ and pH, which was well agreed with theoretically expected results ; $log\;K_d=0.6339pH+0.5532(r^2=0.70^{**})$. Normalization of the partition coefficients were performed in a range of pH 3.5 ~ 8.5 to minimize adverse effects of Al dissolution, cationic competition, and organic matter dissolution. The $K_d$-om, partition coefficients normalized for organic matter, improved this linearity to the pH of soils. The values of $K_d$-om measured from the field samples were significantly correlated with those of $K_d$ predicted from the sorption-edge experimental data ($r^2=0.68^{**}$).

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.7
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• pp.2957-2980
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• 2020

Ensemble clustering commonly integrates multiple basic partitions to obtain a more accurate clustering result than a single partition. Specifically, it exists an inevitable problem that the incomplete transformation from the original space to the integrated space. In this paper, a novel ensemble clustering algorithm using a newly reconstructed mapping coefficient (ECRMC) is proposed. In the algorithm, a newly reconstructed mapping coefficient between objects and micro-clusters is designed based on the principle of increasing information entropy to enhance effective information. This can reduce the information loss in the transformation from micro-clusters to the original space. Then the correlation of the micro-clusters is creatively calculated by the Spearman coefficient. Therefore, the revised co-association graph between objects can be built more accurately because the supplementary information can well ensure the completeness of the whole conversion process. Experiment results demonstrate that the ECRMC clustering algorithm has high performance, effectiveness, and feasibility.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.7 no.4
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• pp.151-158
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• 2014

In this paper, we introduce an inference system using hard scatter partition method and model the nonlinear process. To do this, we use the hard scatter partition method that partition the input space in the scatter form with the value of the membership degree of 0 or 1. The proposed method is implemented by C-Means clustering algorithm. and is used for the initial center values by means of binary split. by applying the LBG algorithm to compensate for shortcomings in the sensitive initial center value. Hard-scatter-partitioned input space forms the rules in the rule-based system modeling. The premise parameters of the rules are determined by membership matrix by means of C-Means clustering algorithm. The consequence part of the rules is expressed in the form of polynomial functions and the coefficient parameters of each rule are determined by the standard least-squares method. The data widely used in nonlinear process is used to model the nonlinear process and evaluate the characteristics of nonlinear process.

• Advances in environmental research
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• v.7 no.2
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• pp.139-159
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• 2018

Green Leaf Volatiles (GLVs) is a class of biogenically emitted oxygenated hydrocarbons that have been identified as a potential source of Secondary Organic Aerosols (SOA) via aqueous oxidation. The physico-chemical properties of GLVs are vital to understanding their fate and transport in the atmosphere via fog processing, but few experimental data are available. We studied the aqueous solubility, 1-octanol/water partition coefficient, and Henry's law constant ($K_H$) of five GLVs at $25^{\circ}C$: methyl jasmonate, methyl salicylate, 2-methyl-3-buten-2-ol, cis-3-hexen-1-ol, and cis-3-hexenyl acetate. Henry's law constant was also measured at temperatures and ionic strengths typical of fog. Experimental values are compared to scarcely-available literature values, as well as estimations using group and bond contribution methods, property-specific correlations and molecular dynamics simulations. From these values, the partition coefficients to the air-water interface were also calculated. The large Henry's law constant of methyl jasmonate ($8091{\pm}1121M{\cdot}atm^{-1}$) made it the most significant GLV for aqueous phase photochemistry. The HENRYWIN program's bond contribution method from the Estimation Programs Interface Suite (EPI Suite) produced the best estimate of the Henry's constant for GLVs. Estimations of 1-octanol/water partition coefficient and solubility are best when correlating an experimental value of one to find the other. Finally, the scavenging efficiency was calculated for each GLV indicating aqueous phase processing will be most important for methyl jasmonate.