• Bulletin of the Korean Chemical Society
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• v.21 no.1
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• pp.105-109
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• 2000

High-performance liquid chromatography is suitable for getting thermodynamic information about solute-solvent interactions. We used a squalane impregnated $C_{18}$ phase as a presumably bulk-like stationary phase to secure a simple partition mechanism for solute retention in reversed phase liquid chromatographic system. We measured retention data of some selected solutes (benzene, toluene, ethylbenzene, propylbenzene, butylbenzene, phenol, benzylalcohol, phenethylalcohol, benzylacetone, acetophenone, benzonitrile, benzylcyanide) at 25, 30, 35, 40, 45, and 50 $^{\circ}C$ in 30/70, 40/60, 50/50, 60/40 and 70/30 (v/v%) acetonitrile/water eluents. The van't Hoff plots were nicely linear, thus we calculated dependable thermodynamic values such as enthalpies and entropies of solute transfer from the mobile phase to the stationary phase based on more than four retention measurements on different days (or weeks). We found that the cavity formation effect was the major factor in solute distribution between the mobile and stationary phases in the system studied here. Our data were com-pared with some relevant literature data.

• Bulletin of the Korean Chemical Society
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• v.15 no.1
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• pp.15-20
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• 1994

The adsorption model in reversed phase liquid chromatography has been critically examined. It has been found that use of the Everett type surface activity coefficient for the solute in the stationary phase is not useful to study the retention characteristics of a nonpolar solute. We suggest a modified model. In this model it is assumed that the displaced modifier molecules from the surface monolayer do not transfer into the bulk mobile phase but stick to the nonpolar solute which has displaced them. In addition, we prefer to use an apparent stationary phase activity coefficient of the soluie instead of the Everett type activity coefficient. This modified adsorption model well explains the mobile and stationary phase effects on the solute retention upon variation of mobile phase composition.

• Bulletin of the Korean Chemical Society
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• v.18 no.6
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• pp.584-588
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• 1997

A new device to accurately deliver small amount of modifier into supercritical carbon dioxide fluid is described. Carbon dioxide, the most widely used mobile phase in supercritical fluid chromatography, is a relatively non-polar fluid, and hence the addition of small amount of polar modifiers could be necessary to migrate polar solutes. In this work, supercritical CO₂and modifier are delivered from the pump to a 100 μL mixing chamber in which a small magnetic bar is rotating. After passing through the mixing chamber, supercritical CO₂is changed to a new mobile phase with different polarity. The amount of modifier added into supercritical CO₂is measured by an amperometric microsensor, which is prepared from a thin film of perfluorosulfonate ionomer.

• Bulletin of the Korean Chemical Society
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• v.13 no.6
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• pp.636-642
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• 1992

Preferential solvation (PS) phenomena of solutes based on solvent polarity, $E_T$ and AN, were studied by UV/vis. and NMR spectra in MeOH binary mixtures. According to the extent of solvent-solvent interaction, different solvation phenomena were found. PS concept was applied to explain the reactivity of tert-butyl halides solvolysis. The findings of solvation phenomena have been related to the rate of solvolysis and PS suggested as a reason for the solvent dependence of the rates of reaction. Moreover, we found that the results of principal components analysis using six parameters are in good accordance with the results of PS phenomena in mixed methanol systems.

• Bulletin of the Korean Chemical Society
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• v.14 no.2
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• pp.250-255
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• 1993

A dual capillary column system is described for the simultaneous analysis of a given sample and measurement of retention index (RI) and area ratio (AR) values of each peak on two capillary columns of different polarity, DB-5 & DB-1701 from a single injection. Both capillary columns were connected to either a splitless injector or an on-column injector via a deactivated fused-silica capillary tubing of 1 m length and a 'Y' splitter. Both injection modes allowed to measure RI and AR values with high reproducibility (<0.01% RSD) and high accuracy (<10% RE), respectively with the exception that the trace and high boiling solutes required the on-column mode for the accurate quantification and AR comparison. When the dual capillary column system in on-column injection mode was applied to the blind samples containing organic acids, each acid was positively indentified by the combined computer RI library search-AR comparison.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.293.1-293.1
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• 2003

Electroosmotic flux during iontophoresis originates due to the net negative charge of the current passing channels (pores) in skin at physiological pH (pH 7.4). Thus, the channels are permselective to cations, and this causes the convective solvent flow from anode to cathodal direction. This solvent flow facilitates the flux of cations (from anode), inhibits that of anions (from cathode), and enables theenhanced transport of neutral, polar solutes. (omitted)

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.233.3-234
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• 2003

Electroosmotic flux during iontophoresis originates due to the net negative charge of the current passing channel (pores) in skin at physiological pH (pH 7.4). Thus, the channel is permselective to cations, and this causes the convective solvent flow, from anode to cathode direction. This solvent flow facilitates the flux of cations (from anode), inhibits that of anions (from cathode), and enables the enhanced transport of neutral, polar solutes. In this work, we have investigated the effect of a series of polyethylene glycols (PEGs) with different molecular weights on the electroosmtic flow to get more detail understanding of this phenomena. (omitted)

• Journal of the Korean Society for Heat Treatment
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• v.35 no.5
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• pp.255-261
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• 2022

In this work, the strain-amplitude independent and strain-amplitude dependent damping capacities of Mg-5%Sn alloy have been investigated as a function of its age-hardening response. The hardness increased with an increase in aging time, reached a peak value after 48 h, and then it gradually decreased. The damping capacities of the Mg-5%Sn alloy exhibited a decreasing tendency in the order of solution-treated, under-aged, peakaged, and over-aged states in the strain-amplitude dependent region, whereas they increased continuously with aging time in the strain-amplitude independent region. The microstructural examination during aging revealed that the lower concentration of Sn solutes in the α-(Mg) matrix and the lower density of the Mg₂Sn precipitate particles may well be the crucial factors for better damping values in the strain-amplitude independent and strain-amplitude dependent regions, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.11
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• pp.649-655
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• 2015

As a novel water treatment membrane, concept of ceramic-based graphene membrane (CbGM) was suggested, and its mass transport behavior was investigated. The selectivity of CbGM was given by graphene material which is consisting of active layer, only transmitting water, but rejecting salts. Filtration-assisted assembly methods was employed as a facile method to fabricate CbGM. Surface morphology and characteristics of CbGM were analyzed by scanning electron microscopy (SEM) and contact angle. In addition, three different kinds of solutes (i.e., NaCl, $MgCl_2$, $Na_2SO_4$) were tested in batch forward osmosis system to confirm the mass transport behavior. Through surface morphology analysis and mass transport behavior, it was revealed that interlocking between graphene layers is very important, rather than thickness of laminated graphene layers, in terms of selectivity to CbGM. All the anions in each solute showed faster transport than those of cations. In addition, solutes which have high ion valence charge ratio of anion to cation ($Z^-/Z^+$) was easier to be passed through CbGM. It indirectly implied that the surface charge of CbGM appear to be positive. In addition, It showed that surface charge of CbGM has a great role on mass transport, in particular, transport of matter having charges, generally ions.

• Journal of Veterinary Clinics
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• v.26 no.1
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• pp.23-28
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• 2009

Peritoneal dialysis (PD) is a clinical technique that therapeutically removes toxic solutes from body fluids and normalizes endogenous solutes whose aberrant concentrations disrupt normal physiology. This study retrospectively evaluated clinical outcomes and complications of PD in 20 dogs with renal failure. Blood works (total count of red blood cells (RBC), packed cell volume (PCV), the serum biochemical, and electrolyte values related to renal insufficiency) and complications associated with peritoneal dialysis, and clinical outcomes were recorded before and after PD. Additionally, creatinine reduction ratio (CRR) and urea nitrogen reduction ratio (URR) were calculated for evaluating the efficacy of PD. PD resulted in a significant (p < 0.05) reduction in blood urea nitrogen (BUN) concentration in 19 dogs, while a significant (p < 0.05) reduction in creatinine concentration in 17 dogs. The complications of PD were hypoalbuminemia (12/20, 60%), anemia (10/20, 50%), subcutaneous dialysate leakage (9/20, 45%), bacterial peritonitis (6/20, 30%), dialysate retention (5/20, 25%) and limb edema (4/20, 20%). This study demonstrated that PD was effective in reducing the magnitude of azotemia in dogs with renal failure especially in acute phase, although the complication rate was high but manageable.