• Preventive Nutrition and Food Science
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• v.21 no.1
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• pp.73-77
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• 2016

Flow and dynamic rheological properties of thickened waters prepared with commercial food thickeners were investigated at different pH levels (3, 4, 5, 6, and 7). The commercial xanthan gum (XG)-based thickener (thickener A) and starch-based thickener (thickener B), which have been commonly used in a domestic hospital and nursing home for patients with swallowing difficulty (dysphagia) in Korea, were selected in this study. Thickened samples with both thickeners at different pH levels showed high shear-thinning flow behaviors (n=0.08~0.22). Thickened samples at pH 3 showed higher n values and lower consistency index (K) values when compared to those at other pH levels. The K values of thickener A increased with an increase in pH level, while the n values decreased, showing that the flow properties greatly depended on pH. There were no noticeable changes in the K values of thickener B between pH 4 and 7. At pH 3, the thickened water with thickener A showed a higher storage modulus (G') value, while that with thickener B showed a lower G'. These rheological parameters exhibited differences in rheological behaviors between XG-based and starch-based thickeners, indicating that the rheological properties of thickened waters appear to be greatly influenced by the acidic condition and the type of food thickener. Appropriately selecting a commercial food thickener seems to be greatly important for the preparation of thickened acidic fluids with desirable rheological properties for safe swallowing.

• Microbiology and Biotechnology Letters
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• v.23 no.4
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• pp.373-377
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• 1995

We investigated the survival, $\beta$-galactosidase activity and cellular permeability of lactic acid bacteria such as Lactobacillus acidophilus ATCC 4356, Lactobacillus casei subsp. casei IFO 3533, Streptococcus thermophilus KCTC 2185, Lactobacillus delbrueckii subsp. lactis ATCC 4797, and Lactobacillus delbrueckii subsp. bulgaricus ATCC 11842 in anaerobic condition of pH 1.5-3.5 range. Numbers of all tested viable cells did not decrease at pH 3.5, but decreased rapidly at pH 1.5 and pH 2.5 during 2 hour incubation at modified EG medium. Immediately after 2 hour incubation, the decrease in population at pH 1.5 and pH 2.5 was about 6-8 and 5-7 log cycles/ml, respectively. Lactobacillus acidophilus ATCC 4356 showed the higest survival of all tested bacteria. The $\beta$-galactosidase activity from Lactobacillus delbrueckii subsp. bulgaricus ATCC 11842 and Streptococcus thermophilus KCTC 2185 decreased rapidly at pH 1.5 and 2.5, but there was a little decrease at pH 3.5. The cellular permeability that was measured by the leakage of intracellular materials increased with decrease of pH. These results suggest that the ingested lactic acid bacteria may be destroyed in contact with low pH of gastric acid.

• Applied Biological Chemistry
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• v.41 no.7
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• pp.505-509
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• 1998

Chitinase, which is one of the pathogenesis-related proteins, was examined from Rehmannia glutinosa. Rehmannia chitinases were classified into basic and acidic groups by chitin affinity column chromatography. According to the chitinase pattern by native PAGE, basic chitinases of low Rf values were extracted more under an acidic condition (pH 2.9) than a basic condition (pH 8.8), while acidic chitinases having high Rf values were mainly detected in basic extracts. There were in total seven chitinase isoforms of three basic and four acidic isoforms in Rehmannia. The range of molecular weight of Rehmannia chitinase was from 28 to 32 kD. It showed the possibility of tissue specific expression of acidic chitinases and basic chitinases were mainly detected in root.

• YAKHAK HOEJI
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• v.26 no.4
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• pp.223-229
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• 1982

Uremia is associated with defective protein binding of weakly acidic drugs, whereas the protein binding of basic drugs tends to be normal. The exact chemical nature of compound(s) and mechanism for these changes as yet is unknown, and has not been defined. Organic solvent extraction of pooled normal human urine following hydrolysis by hydrochloric acid produced an extract, which when added to normal human serum, was capable of inducing binding defects similar to those in uremia. Binding defects were observed with the weakly acidic drugs such as nafcillin, salicylate, sulfamethoxazole and phenytoin while the binding of the basic drugs such as trimethoprim and quinidine were unaffected. The binding defects induced by the hydrolyzed urine extract could readily be corrected by same organic solvent extraction of acidified serum and the defects could be transferred to the normal human serum using the organic solvent layer at the physiologic pH (7.4). Followed by reacidification ind extraction of the binding defects induced serum with the same solvent, separated several fractions were obtained on thin-layer chromatography. One of these fractions could reinduce the binding defects and this factor(s) is apparently weakly acidic compounds and tightly bound to serum at physiologic pH, but extractable at acidic pH, and its molecular weight range is approximately 500 or less similar to those seen in uremia. These findings strongly support the hypothesis that the drug binding defect in uremia is due to the accumulation of endogenous metabolic products which arc normally excreted by the kidneys but accumulate in renal failure.

• Environmental Mutagens and Carcinogens
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• v.17 no.1
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• pp.7-11
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• 1997

Variations in adriamycin uptake and cytotoxicity were studied in tumor cells that were grown in different growth states and microenvironments. RIF-1 tumor cells were maintained in an RPMI 1640 medium, and grown in either a monolayer or multicell spheroids. For exponentially growing cells, adriamycin cytotoxicity increased with increased dosage up to 2.5 $\mu$g/ml, and this cytotoxicity was reduced when the cells were grown in a plateau phase or in an acidic microenvironment (pH 6.6). This reduced cytotoxicity was correlated with the uptake of the drug. For multicell spheroids, the cytotoxicity of the drug was reduced dramatically, and this reduction was also correlated with a reduced uptake of the drug and an acidic pH inside of the spheroids. When the drug cytotoxicity was evaluated at different locations within the spheroids, the cells in the inner regions were least affected by the drug, suggesting that both an acidic microenvironment and noncycling plateau phase cells are contributing factors in decreasing the efficacy of the drug in an organized tissue, such as multicell spheroids.

• Journal of the Korean Home Economics Association
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• v.43 no.7 s.209
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• pp.109-116
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• 2005

Using buffer solutions, consisting of pH 4, 5, 6, 7, and 8, silk fiber fabric specimens, pre-mordanted with one of the mordanting agents, Sn, Al, Cu, Cr, and Fe, were dyed using cochineal dyestuff. The color of the dyed silk fabric specimens was predominantly red(R) for the acidic range of pH 4 and 5, and predominantly purple(RP) for the neutral range of pH 6,7, with 8, with the pH boundary differentiating between the shades being between pH 5 and 6. As a general trend, the chroma value decreased as the pH changed from acid to alkali, and the highest chroma value us attained between pH 4 and 5. Regardless of the mordanting conditions, the trend was that $ {\Delta}E$ showed the highest measured value in the acidic range of pH 4 and 5, and it dropped abruptly after the pH 6.

• The Research Journal of the Costume Culture
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• v.13 no.2 s.55
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• pp.248-254
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• 2005

In this study, wool fabric specimens were pre-mordanted using Sn, Al, Cu, Cr, and Fe, and subsequently dyed using cochineal, maintaining the pH of the dye bath constant using pH buffer solutions of 4, 5, 6, 7, and 8. In the case of wool fabric specimen, regardless of the type of mordanting agents, peak dye-uptake amount was obtained at the acidic region, pH 4, and above pH 6, the dye-uptake amount decreased remarkably. Differing from the cotton fabric case, the dyed wool fabric specimen exhibited red shade even in the case of non-mordanting, at the region of pH values of 4 and 5. It is presumed that in the acidic dye bath the effect of cationic amine group present in the structure of wool fiber molecules took place. The amount of color difference, among the mordanting agents, due to the increase of pH value, was highest for the Fe mordanting case. It seems, therefore, that the Fe mordanting is affected most by the pH value.

• Bulletin of the Korean Chemical Society
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• v.17 no.9
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• pp.820-826
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• 1996

The p2H dependence of the NMR chemical shifts of the proton signals of heme methyl groups and ionizable groups in the vicinity of the heme were investigated. The p2H titration of heme methyl signals in four macroscopic oxidation states by saturation tranfer method was performed in the range between p2H 5.2 and 9.0. While the p2H dependence of the heme methyl resonance in fully oxidized state was small, most resonances in the intermediate oxidation states showed certain shifts. Particularly, methyl resonances of heme 1 (sequential heme numbering) exhibited sharp p2H dependence in acidic range. β-CH2 of the propionate of hemes 1 and 4 were titrated in the range of p2H 4.5-9.0. Only the 6-propionate group of heme 1 was protonated in this p2H range and its titration curve was similar to those of methyl resonances of heme 1 in intermediate oxidation states. Analysis of the microscopic redox potentials showed that they change depending on p2H. The ionizable groups responsible for the p2H dependence of these potentials are 6-propionate of heme 1 in acidic range and His 67 in basic range.

• Journal of the Korean Chemical Society
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• v.66 no.6
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• pp.521-525
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• 2022

• Journal of Korean Society of Water and Wastewater
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• v.21 no.1
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• pp.123-130
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• 2007

The effects of hydrogen peroxide treatment on the reduction of waterworks sludge were investigated in this study. Sludge treated by peroxidation $H_2O_2$ oxidation) was dewatered using a pressure filter at 3atm. It was observed that $H_2O_2$ treatment at the acidic condition significantly reduce both cake water content and specific resistance to filtration (SRF), indicating the enhancement of dewaterability and filterability. The filterability by hydrogen peroxide treatment at pH 3.5 was better than acidic treatment and became comparable with polymer conditioning. The sludge filterability evaluated by SRF was optimal at a dose 2ml $H_2O_2$/sludge($0.02g\;H_2O_2/gTS$) after adjusting of pH to 3.5. The $H_2O_2$ oxidation at pH 3.5 also produced even more dewatered cake when compared with polymer conditioning. The reduction rate of sludge mass at an optimal condition showed 34% compared with untreated sludge. The effects of peroxidation on sludge properties including zeta potential, bound water and particle size were also evaluated. Peroxidation at the acidic condition reduced both bound water and zeta potential. By $H_2O_2$ combined with sulfuric acid leached iron caused Fenton's reaction, which showed a potential to significantly reduce the amount of solids mass and to produce more compact cake with higher filterability.