• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.2
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• pp.342-342
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• 1998

The effect of pH on the dehydration reaction of TiCl₄solution. KOH and HCl were used as a accelerater and retarder in dehydration. Results are follow. Neutralization point is pH 7.4 in the system of $TiCl_4-KOH$ and the production which is produced at acidic side is Ti-gel of poly metatitanic acid. The production which is produced at alkalic side is aligomer and crystalline potasium titanate is not detected.

• Journal of Microbiology
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• v.34 no.4
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• pp.316-319
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• 1996

Mycelia of Streptomyces viridochromogenes grown under different pH were analysed for the fatty acid composition. The low relative proportion of 12-methyltetradecanoic acid and the high relative proportion of palmitic acid were characteristic for the young culture under slight acidic pH that caused delay of the aerial mycelium formation. The addition of L-arginine to the culture medium enabled an arginine auxotroph with bald phenotype to have the fatty acid composition similar to that of the wild type and to develop aerial mycelium. The ratio of 12-methyltetradecanoic acid to palmitic acid might be used as a parameter to explain the optimum grwoth in the respect of membrane fluidity.

• Korean Journal of Human Ecology
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• v.5 no.2
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• pp.119-127
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• 2002

Dyeing properties of the colorants extracted from acorn on wool fabric were investigated. Effects of dyeing temperature, dyeing time, repeating, and pH on dye uptake and colorfastness were explored. Acorn colorants showed very good affinity to wool fiber and produced bright to dark brown color ranged 4.81-8.97YR, 4.46-7.47/1.79-3.35. ,Higher temperature increased dye adsorption, so did longer time and more repeating. Washfastness was fairly good. The Dyed wool fabric had deeper color after irradiation to light. pH had an effect on the development of color, also. Dye uptake and washfastness were higher in acidic and alkaline pH than in neutral pH solution.

• Journal of Environmental Science International
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• v.7 no.2
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• pp.123-132
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• 1998

The experiment was performed to elucidate the effect of simulated acrid rain on growth of the seven crops(caucus carota vu sativa DC. , Fagopyrum esculenkm Moench, Brassica cmpespis subsp. napus var. pekinensis Makino , Raphuus satlws vu. hortensis for. acnMormis Makino, Brassica dbogjabra Bailey, Caphslcum mum L., and Perilla frutescens Britton). The pH levels of simulated acid rain ranged pH 3.1, 3.6, 4.1, 4.6, 5.1 and 5.6. The germination 10 each crop was influenced from stimulated acrid rain except buckwheat and kale. A general decrease of growth in crops was observed with Increasing pH concentrations. The pattern of soluble protein was observed a tendency to decrease from acidic pH eradlents. According to acidity, total DNA contents of each crop was showed a definite reduction. In conclusion, plant growth was stimulated decreasln and the chanties of total Protein Patterns and BNA contents extracted from leaves trended with stimulated acrid rain was showed seriously.

• Korean Chemical Engineering Research
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• v.61 no.4
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• pp.570-575
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• 2023

Targeted anticancer drug delivery systems are needed to enhance therapeutic efficacy by selectively delivering drugs to tumor cells while minimizing off-target effects, improving treatment outcomes and reducing toxicity. In this study, a silica-based nanocarrier capable of targeting drug delivery to cancer cells was developed. First, silica nanoparticles were synthesized by the Stöber method using the surfactant cetyltrimethylammonium bromide (CTAB). Increasing the ratio of EtOH in the solvent produced uniformly spherical silica nanoparticles. Washing the nanoparticles removed unreacted residues, resulting in a non-toxic carrier for drug delivery in cells. Upon surface modification, the pH-responsive polymer, polyethyleneimine (PEI) exhibited slow doxorubicin release at pH 7.4 and accelerated release at pH 5.5. By exploiting this feature, we developed a system capable of targeted drug release in the acidic tumor microenvironment.

• KSBB Journal
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• v.15 no.6
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• pp.548-555
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• 2000

A hydrogel, poly(N-isopropylacrylamide-co-N, N-dimethylaminopropylmethacrylamide), sensitive to both pH and temperature, was synthesized and characterized at $^13∼23{\circ}C$ and pH of 10.3∼12.3. The gel was more transparent and mechanically stronger at lower preparation temperature and pH. Large pores observed in scanning electron microscope seem to be responsible for the lower biomolecular separation efficiency. The lower critical solution temperature (LCST) decreased at a higher polymerization temperature. At $25^{\circ}C$, which is lower than the LCST, the gel was swollen regardless of the solution pH. At $40^{\circ}C$, however, the gel was swollen at neutral and acidic pHs even though the temperature was higher than the LCST. The gel collapse pH, defined as the point at which the gel made its largest volume decrease per unit pH increment, increased as the gel preparation temperature increased.

• Journal of dental hygiene science
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• v.16 no.6
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• pp.464-471
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• 2016

The purpose of this study was to provide information on the labeling of nutritional components on beverages to aid in nutrition education and oral health promotion. The study was conducted to evaluate nutritional effects and risk factors associated with the consumption of different beverages with respect to oral health. A total of 52 products from seven different types of beverages were analyzed for their nutrient content, sugar content, and pH. The sugar content per serving size, based on the nutrition labeling of beverages, was highest for the milk beverages, at 26.6 g, and lowest for the teas, at 13.0 g. According to the recommendation of the World Health Organization (WHO), beverages should contain less than 10% (50 g) total sugars. Our assessment revealed that total sugars in and carbonated beverages were 53.2% and 50.0% of daily value, respectively. Therefore, the milk and carbonated beverages contained more than 50% sugars per serving size, exceeding the recommendation of WHO. The pH of the beverages, from the most acidic to the least acidic were: carbonated beverages, pH 3.0; fruit and vegetable beverages, pH 3.1; mixed beverages, pH 3.6; fruit and vegetable juices, pH 3.7; teas, pH 4.7; coffees, pH 6.6; and milk beverages, pH 6.8. The intake of acidic and sweetened beverages could potentially cause dental caries and erosion. Therefore, the results of this study could be used by oral health care professionals to counsel their patients by providing relevant information on the possibility of oral disease caused by consumption of commercial beverages.

• Membrane Journal
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• v.19 no.3
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• pp.252-260
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• 2009

The effects of the treatment of an acidic solution at pH 2 on polyacrylonitrile ultrafiltration (UF) membranes were investigated using a circular cross-flow filtration bench with a membrane module. A substantial reduction in the membrane permeability was observed after 80 hours' treatment of the acidic solution. In addition, the analyses of the sample solutions by ultraviolet/visible absorption spectroscopy and gas chromatography/mass spectrometry (GC/MS), which were taken from the feed tank as a function of the treatment time, showed that a new organic compound was produced in the course of the treatment. From a thorough search of the mass spectral library we presumed the new compound to be 1,6-dioxacyclododecane-7,12-dione (DCD), one of the well-known additives for polyurethane. Based on further experimental results, including the scanning electron microscope (SEM) images and the solid-state NMR spectra of the membranes used for the treatment of the acidic solution, we suggested that the decrease of the permeate flux resulted not from the deformation of the membranes, but from the fouling by DCD eluted from the polyurethane tubes in the filtration bench during the treatment. Those results imply that the reactivity to an acidic solution of the parts comprising the filtration bench is as important as that of the membranes themselves for effective treatments of acidic solutions, for efficient chemical cleaning by strong acids, and also in determining the pH limit of the solutions that can be treated by the membranes.

• Corrosion Science and Technology
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• v.21 no.4
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• pp.273-281
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• 2022

The effect of addition of Cu on the localized corrosion performance of aged duplex stainless steel in chloride media has yet to be explained in a consistent manner, and there is some controversy in the literature regarding the composition of stainless steel and the experimental conditions (pH, temperature, chloride concentration, etc.) used. In this work, the effect of the addition of Cu on the microstructure, hardness, and corrosion resistance of duplex stainless steel in an acidic chloride or high concentration sulfuric acid solutions was investigated for annealed and aged alloys. The Cu addition of annealed duplex stainless steel strengthened the alloy and reduced the ferrite contents of the alloy, and it also increased the polarization behavior in chloride or sulfuric solutions, except for the case of a high potential in acidic chloride solution. However, the Cu addition of aged duplex stainless steel reduced the formation of harmful phases such as sigma and kai and increased the polarization behavior in acidic chloride or sulfuric solutions up to 0.8 wt% of the Cu content, after which it slightly decreased at 0.8 wt% Cu or more.

• Korean Journal of Environmental Agriculture
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• v.12 no.2
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• pp.169-175
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• 1993

O-Ethyl S-methyl ethylphosphonothioate was studied for chemical and metabolic oxidation using $^{31}P-NMR$ analyses. The chemical shifts of O-ethyl ethylphosphonic acid (2) which is one of major metabolites were changed with the variation of oxidation systems. $^{31}P-NMR$ chemical shifts of 2 were observed at 40.15ppm from oxidaton by MCPBA, 30.98 ppm by MMPP, 29.31 ppm from in vitro rat liver microsomal oxidation, and 29.10 ppm from in vivo metabolism in houseflies. $^{31}P-NMR$ chemical shift of 2 in two different solvents such as deutero-chloroform and deuterium oxide were observed at 30.70 ppm and 40.15 ppm, respectively. And those of the metabolites were also observed at around 30 ppm under the conditions of pH 3, 5.6 and 14 and 47.91 ppm under pH 1 which is a strong acidic condition. It could be explained that the ionized form of 2 should have greater shielding effect on phosphorus atom and hence shows upfield chemical shift in polar solvents and alkaline conditions. On the other hand, a protonated form under organic solvents and the strong acidic condition should have less shielding effect than its ionized form, shifting the peak downfield.