• Journal of Pharmaceutical Investigation
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• v.40 no.spc
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• pp.9-17
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• 2010

Polymorphism has been recognized to be a critical issue throughout the drug product development process. Most of solid phase drugs have polymorphism, which has generated a great deal of interest and the field has been evolving rapidly. Preferably, thermodynamically most stable form of a drug substance is selected to obtain consistent bioavailability over its shelf life and various storage conditions. Moreover, it has the lowest potential for conversion from one polymorphic form to another. However, metastable or amorphous forms may be used intentionally to induce faster dissolution rate for rapid drug absorption and higher efficacy. For pharmaceutical industry, polymorphism is one of the key activities in form selection process together with salt selection. This article introduces the main features in the investigation of solid form selection especially polymorphic behavior with thermodynamic backgrounds, physicochemical properties with solubility, dissolution, and mechanical properties, and characterization techniques for proper analysis. The final form can be recommended based on the physicochemical and biopharmaceutical properties and by the processability, scalability and safety considerations. Pharmaceutical scientists especially in charge of formulation need to be well aware of the above issues to assure product quality.

• Bulletin of the Korean Chemical Society
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• v.16 no.10
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• pp.934-938
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• 1995

A series of solid solutions in the Ca2AlxFe2-xO5 (x=0.00, 0.50, 0.66, 1.00 and 1.34) system with brownmillerite structure has been synthesized at 1100 ℃ under an atmospheric air pressure. The solid solutions are analysed by powder x-ray diffraction analysis, Mohr salt titration, thermal analysis, and Mossbauer spectroscopic analysis. The x-ray diffraction analysis assigns the compositions of x=0.00 and 0.50 to the space group Pcmn and those of x=0.66, 1.00, and 1.34 to the Ibm2. Mo&ssbauer spectra have shown the coordination state and disordering of Al3+ and Fe3+ ions. The substituting preference of Al3+ ions for the tetrahedral site decreases with increasing x value. Magnetic susceptibility of the system has been measured in the temperature range of 5 K to 900 K. The solid solutions of the compositions of x=0.00, 0.50 and 0.66 have shown a thermal hysteresis and the thermoremanent magnetization gap decreases with increasing x value in the above systems. However the compositions of x=1.00 and 1.34 do not show the hysteresis. The exchange integral is calculated from Fe3+ ion occupancy ratio. The integral decreases with x value and thus the magnetic transition temperature decreases with the increasing x value.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.4
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• pp.481-486
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• 1995

The salt stress at seedling stage of winter barley was examined in different concentrations of NaCl containing 1/2 Hoagland solution. Fresh weight of seedling at 30 days after seeding was highest at 25mM of NaCl concentration containing 1/2 Hoagland solution but if the NaCl concentration was more than 50mM it began to decrease seriously. Water content in plant was decreased according to increase of NaCl concentration in 1/2 Hoagland solution, so physiological mechanism of NaCl in barley was different from saline plant. Stoma number per cm$^2$ of first leaf was higher than that of control in case of stressed by NaCl but in that case the leaf length was decreased so the number of stoma per first leaf was slightly decreased. Chloroplast shape was not changed by 75mM of high NaCl contained 1/2 Hoagland solution but cell division at root growing point was inhibited by 75mM of NaCl. As the result of salt stress mitochondria was ruined in structure and irregular solid was found to be transfered from the cytoplasm to the cell wall in root growing point.

• Korean Journal of Plant Resources
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• v.24 no.2
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• pp.208-213
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• 2011

This study was carried out to determine the effect of medium solidity, salt strength, sugar and nitrogen sources, and pH levels on in vitro multiplication of pathogen-free yam (Dioscorea opposita Thunb.). Liquid medium was more effective in the growth of plant height, fresh weight, and formation of microbulb than the solid medium. Optimal condition for plant fresh weight, growth, and multiplication axillary bud was in 1MS salt strength with 60 $g{\cdot}L^{-1}$ sucrose and half strength of $KNO_3$. Optimal condition for microbulb formation was $\frac{1}{2}$ MS salt strength supplemented with glucose 60 $g{\cdot}L^{-1}$ and half strength of $KNO_3$. The number of leaves and nodes were sharply increased from 2 to 5 weeks, whereas plant fresh weight was steadily increased from 3 to 11 weeks after inoculation. Microbulbs were formed at 2 weeks after inoculation and continuously increased until 12 weeks.

• Journal of the Korean institute of surface engineering
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• v.51 no.2
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• pp.95-103
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• 2018

Recently, many types of constructional steels have been often exposed to under severe corrosive environments due to acid rain with increasing environmental contamination. In order to inhibit their corrosion in severe corrosive environments, a painting method has been widely applied to numerous constructional steels of land as well as marine. Therefore, development of paint having a good quality of corrosion resistance is considered to be very important. In this study, four types of anti-corrosive paints (AP: Phenol epoxy, AC: Ceramic epoxy, AT: Coal tar epoxy, AH: High solid epoxy) were coated to the specimens, and then, were immerged in various salt solutions (0.1, 0.3, 3, 6, 9 and 15% NaCl solutions) for 11 days. And, the corrosion resistance of these samples by effect of osmotic pressure with salt concentration was investigated with electrochemical methods such as measurement of corrosion potential, impedance and corrosion current density. The corrosion current densities of all samples (AC, AT and AH) submerged in 3% NaCl solution exhibited the smallest values compared to other salt solutions. However, in the case of lower values of salt solutions than 3% NaCl solution, the corrosion current density increased again because it makes easier for water, dissolved oxygen and chloride ion etc. to invade toward inner side of coating film due to increasing of the osmotic pressure than 3% NaCl solution, but in the case of higher values of salt solutions than 3% NaCl solution, the coating film is easily deteriorated due to high concentration of chloride ion rather than the osmotic pressure, which resulted in increasing the corrosion current density. In particular, the AC sample indicated the best corrosion resistance in 6% NaCl solution compared to other samples. Consequently, it is considered that the corrosion mechanism of the coated steel plate is completely different from bare steel plate, and the corrosion resistance of coating film by osmotic pressure and chloride ion depend on various types of epoxy of paint in NaCl solution.

• Journal of Pharmaceutical Investigation
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• v.24 no.2
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• pp.57-65
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• 1994

To increase the dissolution rate of practically insoluble biphenyl dimethyl dicarboxylate (DDB), various solid dispersions were prepared with water soluble carriers, such as povidone (PVP K-30), poloxamer 407, sodium deoxycholate (SDC) and polyethylene glycol (PEG) 6000, at drug to carrier ratios of 1:3, 1:5 and 1:10 (w/w) by solvent or fusion method. Dissolution test was performed by the paddle method. The dissolution rate of DDB tablets (25 mg) on market was found to be very low (11.44, 9.02 and 6.42% at pH 1.2, 4.0 and 6.5 after 120 min, respectively). However, dissolution rates of DDB from various solid dispersions were very fast and reached supersaturation within 10 min. DDB-PEG 6000 solid dispersion appeared to be better in enhancing the in vitro dissolution rate than others. Furthermore, the incorporation of DDB and phosphatidylcholine (PC) into ${\beta}-cyclodextrin$ at ratios of 1:2:20, 1:5:20 and 1:10:20 resulted in a 4.9-, 11.2- and 19.6-fold increase in DDB dissolution after 120 min as compared with the pure drug, respectively. This might be attributed to the formation of lipid vesicles which entrapped a certain concentration of DDB during dissolution. On the other hand, the permeation of DDB through rabbit duodenal mucosa was examined using some enhancers such as SDC, sod. glycocholate (SGC) and glycyrrhizic acid ammonium salt (GAA). Only trace amounts of DDB were found to permeate through deuodenal mucosa in the absence of enhancer. SDC was found to markedly decrease the permeation flux of DDB, however, SGC and GAA (5 mM) enhanced the flux of DDB 1.6 and 2.4 times higher as compared with no additive, respectively.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.6
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• pp.559-572
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• 2018

The aim of this study was to evaluate pretreatment methods for 27 pharmaceuticals and personal care products (PPCPs) in various sewage samples using a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) and online solid-phase extraction with LC-MS/MS. Extraction efficiencies of PPCPs in the solid phase under different experimental conditions were evaluated, showing that the highest recoveries were obtained with the addition of sodium sulfate and ethylenediaminetetraacetic acid disodium salt dehydrate in acidified conditions. The recoveries of target compounds ranged from 91 to 117.2% for liquid samples and from 61.3 to 137.2% for solid samples, with a good precision. The methods under development were applied to sewage samples collected in two sewage treatment plants (STPs) to determine PPCPs in liquid and solid phases. Out of 27 PPCPs, more than 19 compounds were detected in liquid samples (i.e., influent and effluent) of two STPs, with concentration ranges of LOQ-33,152 ng/L in influents and LOQ-4,523 ng/L in effluents, respectively. In addition, some PPCPs such as acetylsalicylic acid, ibuprofen, and ofloxacin were detected at high concentrations in activated sludge as well as in excess sludge. This methodology was successfully applied to sewage samples for the determination of the target compounds in STPs.

• Korean Journal of Food Science and Technology
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• v.29 no.1
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• pp.183-187
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• 1997

The analytical conditions of 1,3-dichloro-2-propanol (DCP) and 3-chloro-1,2-propanediol (MCPD) by solid phase extraction were optimized to improve recovery. Selected-ion monitoring technique which was used for GC-MS analysis of both compounds gave substantially higher sensitivity. The detection limits of DCP and MCPD were 25 and 50 ppb, respectively. The effects of extraction column type, elution solvent and salt concentration on recovery were examined. A normal phase column was better than a reverse phase column in solid phase extraction of DCP and MCPD. It was explained in terms of polarity relationship of solvent-solute-solid phase. A maximum recovery was obtained at the salt concentration of 20% (w/v). Water-immiscible and chloropropanol-soluble solvents such as chloroform, diethyl ether, hexane and ethyl acetate were tested for elution solvent. Hexane and ethyl acetate were the most suitable solvents for the extraction of DCP and MCPD, respectively. High recovery better than 95% was obtained with the selected solvents.

• Journal of the Korean Chemical Society
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• v.9 no.4
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• pp.179-184
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• 1965

Korean acid clays and Japanese acid clay were 1 N KCl solution and then their acidities were determined by measuring pH of the filtrates produced. And on examining the effect of neutral salt solution, such as KCl, NaCl, $BaCl_2,\;Pb(NO_3)_2\;and\;CuSO_4$, on the acidity, it was found that the effect decreased in order mentioned above and this situation proved to be in accord with Lyotrope series, i.e., the order of $K^+>Na^+>Ba^{++}>Pb^{++}>Cu^{++}.$ And after adsorbing cation, $Al_2O_3\;and\;Fe_2O_3$ which dissolved out of acid clay were measured, with the result that the amounts dissolved out were nearly proportional to acidity. This result accords with Kobayashi and Yamamoto's theory that the cause for acidity of clays is due to the fact that HCl which is formed initially by exchange of cation reacts with solid clay, and then chlorides dissolved out bring about hydrolysis, then resulting in the second formation of HCl. On measuring the rate which acid clay adsorbed dye in aqueous solution of basic and acid dyes, it was found that acid dye had no relation to acidity, and though it was not adsorbed by acid clay, the adsorption rate of basic dye was proportional to acidity. After adsorbing basic dye, pH was proportional to both acidity of solid acid and its adsorption rate of dye. Hence, it was concluded that the adsorption of basic dye was in accord with adsorption mechanism of neutral salt. This study led to find the acidic cause of solid acid and its adsorption mechanism of dye in aqueous solution.

• Journal of the Korean Society of Food Science and Nutrition
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• v.17 no.3
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• pp.255-261
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• 1988

For the purpose of fermentation control and edible period extension of lower salted Kimchi, the contents and compositions of pectic substances in Kimchi, by adding 2 percent salt and 0.4 percent sodium malate buffer(SMB), fermented at $20^{\circ}C$ were investigated. Edible period of SMB added chinese cabbage Kimchi was extended 40 hrs compared to that of control (added 2.5% salt) with good flavor, texture and freshness. The contents of alcohol insoluble solid(AIS) and protopectin(PP) of control were more decrensed during fermentation than those of SMB added Kimchi. But, the contents of pectic adid(PA) and water soluble pectin(WSP) of control were more increased during fermentation than those of SMB added Kimchi. Hexose and pentose from hemicellulose in control, PP and PA respectively, were more decreased during fermentation than those in SMB added Kimchi. Lower polarity and higher molecular weight PP was eluted and higher polarity and lower molecular weight PP was decreased considerably in control compared to those in SMB added Kimchi during fermentation.