• Membrane Journal
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• v.8 no.3
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• pp.157-169
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• 1998

The effects of solvents (DMAc, NMP, 1,4-dioxane) and nonsolvents ($H_2O$, Methanol, n-hexane) on the morphology of 6FDA-p-TeMPD polyimide membrane, prepared by the wet phase inversion method, were studied. In the polymer/solvent/nonsolvent ternary system, the binodal curve, the coagulation value and the relative light transmission were measured, and the solubility parameter difference was calculated. The onset state and rate of liquid-liquid alemixing were predicted and the morphology of membrane was analyzed. It is found that the finger-like pores are formed within discontinuous polymer nodules when the binoclal curve is close to the polymer-solvent (P-S) axis, the coagulation value is small, the reduction of light transmission is easy to occur and the order of solubility parameter difference ($\Delta \delta_{i-j}$) is $\Delta \delta_{S-NS} > \Delta \delta_{P-NS} > \Delta \delta_{P-S}$. The dense skin with small nodules and the sponge type sublayer with macrovoid are formed in the case that the binodal curve is distant from the P-S axis, the onset time of liquid-liquid demixing is long and the order of $\Delta \delta_{i-j}$ is $\Delta \delta_{P-NS} >(\Delta \delta_{S-NS} < > \Delta \delta_{P-S})$. The thick layer of fine nodule coagulation and loosely grown sublayer of nodules appear when the binodal curve is distant from the P-S axis, the onset time of liquid-liquid demixing is very long and the order of $\Delta \delta_{i-j}$가 $\Delta \delta_{S-NS} > (\Delta \delta_{P-NS}$\lessgtr$ > (\Delta \delta_{P-NS} < >)\Delta \delta_{P-S}$ ).

• Journal of Life Science
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• v.31 no.5
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• pp.502-510
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• 2021

The objective of this study was to develop a novel ticagrelor-loaded self-nanoemulsifying drug delivery system with an enhanced solubility and dissolution rate. Numerous oils and surfactants were screened, then medium chain triglyceride (MCT) oil and the surfactants polyoxyethylene sorbitan monooleate (Tween 80) and Labrafil M1944CS were selected for the preparation of the ticagrelor-loaded self-nanoemulsifying drug delivery system. A pseudo-ternary phase diagram was constructed to detect the nanoemulsion region. Of the various formulations tested, the liquid SNEDDS, composed of MCT (oil), Tween 80 (surfactant), and Labrafil M1944CS (cosurfactant) at a weight ratio of 20/70/10 produced the smallest emulsion droplet size (around 20.56±0.70 nm). Then, particle size, polydispersity, and zeta potential were measured using drugs containing liquid SNEDDS. The selected ticagrelor-loaded liquid SNEDDS was spray-dried to convert it into a ticagrelor-loaded solid SNEDDS with a suitable inert carrier, such as silicon dioxide, calcium silicate, or magnesium aluminometasilicate. The solid SNEDDS was characterized by scanning electron microscopy, transmission electron microscopy, and in vitro dissolution studies. SEM, PXRD, and DSC results suggested that amorphous ticagrelor was present in the solid SNEDDS. Also, the solid SNEDDS significantly increased the dissolution rate of ticagrelor. In particular, the emulsion particle size and the polydispersity index of the solid SNEDDS using silicon dioxide (SS1) as a carrier was the smallest among the evaluated solid SNEDDS, and the flowability and compressibility result of the SS1 was the most suitable for the manufacturing of solid dosage forms. Therefore, solid SNEDDS using silicon dioxide (SS1) could be a potential nano-sized drug delivery system for the poorly water-soluble drug ticagrelor.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.2
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• pp.193-201
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• 2000

Partitioning of hydrophobic organic compounds (HOCs) to a biosurfactant, hydroxypropyl-${\beta}$-cyclodextrin (HPCD), was conducted to evaluate the feasibility of using HPCD to remove HOCs from soil/groundwater. HOC partitioning to HPCD was very fast, with over 95% of the complexation occurring within 10 min. Some influence of solution chemistry and HOC concentration on HOC-HPCD complex formation coefficients was observed. HPCD sorption on soil as quantified by both a fluorescence technique and total organic carbon measurements was negligible, indicating no significant affinity of HPCD for the solid phase. Although the HOC solubilization capability of HPCD was lower than that of synthetic surfactants such as SDS and Tween 80, HPCD can be effective in removing sorbed HOCs from a model subsurface environment, primarily because of its negligible sorption to the solid phase (i.e., all the HPCD added facilitates HOC elution). However, in contrast with conventional surfactants, HPCD becomes relatively less effective for HOC partitioning with increasing HOC size and hydrophobicity. Therefore, comparisons between HPCD and synthetic surfactants for enhanced remediation applications must consider the specific HOC(s) present and the potential for surfactant material losses to the solid phase, as well as other more generally recognized considerations such as material costs and potential toxicological effects.

• Journal of the Mineralogical Society of Korea
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• v.5 no.2
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• pp.72-78
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• 1992

The Earth outer core accomodates moderately considerable amount of lighter elements than pure iron itself. Hydrogen is one of the possible candidates of minor constituents in the outer core. It would be worth while to extend for the pressure effect on the solubility of hydrogen in the metal-hydrides including iron hydride. In view of hydrogen being one of the potential substitutes for petroleum, searching a more efficient way for storing hydrogen in the form of hydrides is of considerable value. For two purposes, $TiH_2$was selected among lot of hydrides for its characteristics under pressure and temperature. There have been two kinds of experiment carried out on $TiH_2$ under different experimental conditions. As one of these attempts, polycrystalline $TiH_2$ was loaded up to 15 GPa stepwise at the constant temperature 500${\circ}$ using a piston-cylinder diamond anvil cell equipped with a miniature furnace of an electric power supply. The X-ra diffraction technique was employed on the quenched samples after the simultaneous high pressure and temperature treatments. During these high pressure-temperature runs, and irreversible phase of $TiH_2$ has been observed at the pressures higher than 11.3 GPa, which would be assigned to the orthorhombic crystal system as one of the new phase(s) of $TiH_2$. Molar volume change on this phase transition is ∼10%.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.40 no.2
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• pp.133-139
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• 2014

Oil-in-water nanoemulsions were prepared in the system of water/Span 80-Tween 80/long-chain paraffin oil via the PIC (phase inversion composition) method. With the increase of preparation temperature from $30^{\circ}C$ to $80^{\circ}C$, the diameter of emulsion droplets decreased from 120 nm to 40 nm, proving the formation of nanoemulsions. By varying the HLB (hydrophilic lipophilic balance) of mixed surfactants, we found that there was an optimum HLB around 12.0 ~ 13.0 corresponding to the minimum droplet size. The viscosity of nanoemulsions clearly increased with droplet volume fraction, f, but the droplet size slightly increased. Significantly, at ${\phi}{\leq}0.3$, the size distribution of nanoemulsions kept constant more than 2 months. These results proved that the viscous paraffin oil can hardly be dispersed by the PIC method at $30^{\circ}C$, but the increase in preparation temperature makes it possible for producing monodisperse nanoemulsions. Once the nanoemulsion is produced, the stability against Ostwald ripening is outstanding due to the extremely low solubility of the liquid paraffin oil in the continuous phase. The highly stable nanoemulsions are of great importance in cosmetic applications.

• The Korean Journal of Food And Nutrition
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• v.10 no.2
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• pp.234-240
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• 1997

Agar has widely been used as medical aids and food ingredients due to its pecular physicochemical and rheological properties. In this paper, the effects of spray drying and extrusion drying on functional properties of agar were investigated to clarify the sol-gel transition mechanism at low temperature and microstructure of agar gel by measuring phase transition by differential scanning calorimetery, structural differences by light microscope and scanning electron microscope observation. The lowest endothermic onset(To), peak(Tp), conclusion(Tc) temperature and enthalpy($\Delta$H) using differential scanning calorimetery were showed in extrusion-dried agar wic were checked in 41.30, 61.72, 80.50 and 0.73cal/g. In cases of unmodified and spray-dried, the values were 81.20, 95.51, 112.14 and 3.22cal/g, and 60.11, 76.45, 89.54 and 1.53cal/g, respectively. When all samples were reheated using differential scanning calorimetery after gelling fully, no significant differences of endothermic To, Tp, Tc and $\Delta$H appeared. The surface structure of unmodified agar powder observed by light microscope and scanning electron microscope appeared a continuous surface without any indication of small pores, gaps or point of discontinuity. In cases of spray-dried agar, the unstable structures with pores was resulted. The microstructures of extrusion-dried agar, however, was solid with large gaps and areas of discontinuity in the surface. From the results above, it was suggested that significant differences in phase transition and surface microstructures were clearly related to the physicochemical changes and rheological properties, solubility and gelling ability of the types of agar gel.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.1
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• pp.57-63
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• 2010

Layer crystallization process was tested for the separation(or concentration) of cesium and strontium fission products in a LiCl waste salt generated from an electrolytic reduction process of a spent oxide fuel. In a crystallization process, impurities (CsCl and $SrCl_2$) are concentrated in a small fraction of the LiCl salt by the solubility difference between the melt phase and the crystal phase. Based on the phase diagram of LiCl-CsCl-$SrCl_2$ system, the separation possibility by using crystallization was determined and the molten salt temperature profile during layer crystallization operation was predicted by using mathematical calculation. In the layer crystallization process, the crystal growth rate strongly affects the crystal structure and therefore the separation efficiency. In the conditions of about 20-25 l/min cooling air flow rate and less than 0.2g/min/$cm^2$ crystal flux, the separation efficiency of both CsCl and $SrCl_2$ showed about 90% by the layer crystallization process, assuming a LiCl salt reuse rate of 90wt%.

• Membrane Journal
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• v.15 no.4
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• pp.272-280
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• 2005

In this study, asymmetric polysulfone membranes were prepared by the phase inversion method and the casting solutions were containing N-methyl-2-pyrrolidone (NMP) as a solvent. Deionized water and various alcohols(methanol, ethanol, and propanol) were used as a coagulation medium in preparing asymmetric polysulfone membranes. This study investigates the effect of alcohol coagulants having different solubility parameters as a pore-former on the construction of porous structures and their pure water permeation properties. Asymmetric polysulfone membranes immersed in the pure alcohol coagulation bath solution showed the typical sponge-like structures and the reduced water permeability as compared with those of polysulfone membranes precipitated in the pure water coagulation bath solution. In the water/alcohol mixtures, asymmetric polysulfone membranes showed the finger-like structures with the sponge-like structures. Therefore, the sponge-like structure of polysulfone membrane was formed under the delayed demixing systems while the porosity of membrane was decreased significantly. The water permeability of polysulfone membrane precipitated in the pure water coagulant showed 164 [$L/m^2hr$] at 14.7 psi. In case of polysulfone membranes prepared in the pure methanol and ethanol coagulant, they showed the water permeability of 56 and 30 [$L/m^2hr$], respectively.

• Applied Chemistry for Engineering
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• v.25 no.3
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• pp.274-280
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• 2014

Polysulfone (PSf) hollow fiber membranes were prepared via the nonsolvent induced phase separation technique. The cosolvent of ${\gamma}$-butyrolactone (GBL) was added to the polymer solution containing a mixture of PSf and N,N-dimethylacetamide (DMAc). Water was utilized as a precipitation nonsolvent. The morphology of prepared membranes was investigated using a field emission scanning electron microscopy. The fabricated membrane showed a typical asymmetric structure such as the dense layer on the porous support layer by the addition of GBL to the polymer solution. As the concentration of GBL increased, the asymmetric porous structure was shown to be more intensified. It was thought that the added GBL played a role of enhancing the liquid-liquid phase separation of the polymer solution, since the cosolvent of GBL might change the thermodynamic solubility parameter of the doping solution. Permeation properties through the prepared hollow fiber membranes were characterized by measuring the pure water flux and the solute rejection using $0.05{\mu}m$ polystyrene latex (PSL) beads. Experimental results revealed that the use of PEG as the internal coagulant enhanced the pure water flux up to 130 times compared to the use of EG while the rejection of the PSL beads decreased only 5%.

• Resources Recycling
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• v.33 no.2
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• pp.54-61
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• 2024

When steel contaminated with Pb, produced by the decay of natural radionuclides, is remelted, Pb distributes among the metal, slag, and gas phases. In this study, 5 wt%Pb was added to Fe and melted with CaO-SiO₂-Al₂O₃-MgO slag to investigate Pb's distribution in the metal/slag/gas. As slag basicity ((wt%CaO)/(wt%SiO₂)) increased, Pb solubility in Fe slightly increased, while Pb in the slag tended to decrease. Consequently, the slag/metal distribution ratio of Pb decreased with increasing basicity. Thermodynamic calculations revealed that the slag/Fe phase distribution ratio of Pb remained very low irrespective of the activity coefficient of PbO in the slag, consistent with the experimental results. The calculated evaporation rate of Pb in Fe-Pb was approximately 22 times that of Fe; hence, most of the Pb evaporated into the gas phase.