• Korean Journal of Food Science and Technology
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• v.29 no.6
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• pp.1094-1100
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• 1997

Effects of sodium hypochlorite (NaOCl) concentration, temperature and pH on oxidation mechanism of corn starch were investigated. The rate of oxidation was dependent on the concentration of hypochlorite, pH and temperature of oxidation. The reaction was either first or second order depending on the concentration of NaOCl. At oxidant concentration of $0.75{\sim}3.0%$ active Cl/g starch, the reaction was first-order and it was second-order at $3.75{\sim}4.5%$ active Cl/g starch. The first-order rate constants were increased with increasing oxidant concentration. The rate of oxidation of starch was highest at pH 7 and decreased with increasing acidity or alkalinity of the medium. As the reaction temperature increased, the rate of oxidation was increased.

• Applied Chemistry for Engineering
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• v.34 no.3
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• pp.318-325
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• 2023

The detection of antibiotics in treated wastewater is a global concern as it enters water bodies and causes the development of antibiotic resistance genes in humans and marine life. The study specifically aims to explore the potential of ferrate (VI) in eliminating tetracycline (TCL). The degradation of TCL is optimized with parametric studies, viz., the effect of pH and concentration, which provide insights into TCL elimination. The increase in pH (from 7.0 to 10.0) favors the percentage removal of TCL; however, the increase in TCL concentrations from 0.02 to 0.3 mmol/L caused a decrease in percentage TCL removal from 97.4 to 29.1%, respectively, at pH 10.0. The time-dependent elimination of TCL using ferrate (VI) followed pseudosecond-order rate kinetics, and an apparent rate constant (kapp) was found at 1978.8 L² /mol² /min. Coexisting ions, i.e., NaNO₃, Na₂HPO₄, NaCl, and oxalic acid, negligibly affect the oxidation of TCL by ferrate (VI). However, EDTA and glycine significantly inhibited the elimination of TCL using ferrate (VI). The mineralization of TCL using ferrate (VI) was favored at higher pH, and it increased from 18.57 to 32.52% when the solution pH increased from pH 7.0 to 10.0. Additionally, the real water samples containing a relatively high level of inorganic carbon spiked with TCL revealed that ferrate (VI) performance in the removal of TCL was unaffected, which further inferred the potential of ferrate (VI) in real implications.

• Journal of Life Science
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• v.9 no.2
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• pp.169-175
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• 1999

Salmonella typhimurium can encounter a wide variety of environments during its life cycle. In nature, S. typhimurium can experience and survive dramatic acid stresses that occur in diverse ecological niches ranging from pond water to phagolysosomes. These survival mechanism is aquired by the Acid Tolerance Response(ATR) in Salmonella. The ATR of S. typhimurium is a complex inducible phenomenon in which exposures to slight or moderate low pH will produce a stress response capable of protecting the organism against more severe acid challenges. ATR in Salmonella has two different systems that are called RpoS dependent and independent. We found that ATR in anaerobic was showed RpoS independent because rpoS$\Omega$AP had ATR as S. typhimurium UK1. Using the P22 MudJ(Km, lacZ) operon fusion technique and a lethal selection procedure combining low pH(pH4.5) and sodium acetate(10mM, pH4.5), we isolated LF487 aatA::MudJ which showed acid sensitive in anaerobic condition. aatA locus was determined at 12 min on Salmonella Genetic Map. The survival rate of aatA mutant was showed significantly diminished at pH4.3 than virulent wild type Salmonella in anaerobic condition(5% $CO_2$, 5% H$_2$, 90% $N_2$). Therefore isolated gene was confirmed important gene for anaerobic ATR system.

• Journal of Microbiology and Biotechnology
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• v.28 no.4
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• pp.520-526
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• 2018

Conessine, a steroidal alkaloid, is a potent histamine H3 antagonist with antimalarial activity. We recently reported that conessine treatment interferes with $H_2O_2$-induced cell death by regulating autophagy. However, the cellular signaling pathways involved in conessine treatment are not fully understood. Here, we report that conessine reduces muscle atrophy by interfering with the expression of atrophy-related ubiquitin ligases MuRF-1 and atrogin-1. Promoter reporter assay revealed that conessine treatment inhibits FoxO3a-dependent transcription, $NF-{\kappa}B$-dependent transcription, and p53-dependent transcription. We also showed by quantitative RT-PCR and western blot assays that conessine treatment reduced dexamethasone-induced expression of MuRF1 and atrogin-1. Finally, we demonstrated that conessine treatment reduced dexamethasone-induced muscle atrophy using differentiated C2C12 cells. These results collectively suggest that conessine is potentially useful in the treatment of muscle atrophy.

• Journal of Plant Biology
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• v.38 no.1
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• pp.11-18
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• 1995

Mercury-induced changes in Chl a fluorescence induction kinetics of scratched barley leaf segments were dependent on the presence of light. By the treatment of 50$\mu$M HgCl2 under light condition, Fm and Fp were decreased. However, they were not significantly reduced under dark condition even after 2 h of mercury treatment. Under dark condition the decrease in variable fluorescence (Fv) after P transient was blocked within 20 min of the treatment. The analysis of fast fluorescence rise curve suggests that the inhibitory site of mercury under both light and dark conditions is not at QB binding site and the inhibition does not involve the increase in inactive PSII centers. Under light condition the decrease in Fp was partially recovered by addition of 50 $\mu$M NH2OH. These results suggest that a major inhibitory site of mercury under dark condition is at the reducing side of PSII and the site under light condition is at the oxidizing side of PSII possibly in addition to the one under dark condition. Under both light and dark conditions, energy-dependent quenching(qE) was alomost completely repressed within 20 min of mercury treatment and noticible change in Fo was not observed. The qE repression is probably due to the blockage of transthylakoid ΔpH formation.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.50.2-50.2
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• 2021

There is increasing evidence that the convective mixing length (α) in stellar evolution models depends on metallicity of stars. In order to confirm a more precise metallicity-dependent mixing length trend, we investigate the effective temperature and metallicity of 14 red supergiant stars (RSGs) in the irregular dwarf galaxy IC 1613 using the near-infrared spectra observed with the MMIRS on the MMT telescope. From the synthetic spectral fitting to the observed spectra, we find that the mean metallicity is about [Fe/H]=0.69 with a weak bimodal distribution. We also find that the effective temperature of RSGs in IC 1613 is higher by about 250 K than that of the SMC on average. We compare the RSG position with stellar evolutionary tracks on the HR diagram, finding that models with α = 2.2-2.4 H_p can best reproduce the effective temperatures of the RSGs in IC 1613. It is evident that the mixing length values for IC 1613 is lower than that of the Milky Way. This result supports our previous study on a metallicity-dependent mixing length: mixing length decreases with decreasing metallicity of host galaxies. However, this dependency becomes relatively weak for RSGs having a metallicity equal to or less than the SMC metallicity.

• Journal of Microbiology and Biotechnology
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• v.7 no.6
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• pp.378-385
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• 1997

Cation motive ATPases on cell membranes of Helicobacter pylori were investigated using everted membrane vesicles. Latent ATPases could be ascertained from aggregated vesicle using N, N-dimethylformamide (DMF) and Triton X-100. By contrast, ultrasonication or chloroform treatments caused membranes to be disrupted, resulting in an alteration of sensitivities against azide or vanadate. Considerable amounts of vanadate-sensitive enzymes were identified from vesicle micelles, prepared by the dilution method. These were activated in the presence of either $Ni^{2+}\;or\;NH_4^+$. From studies employing H. pylori intact cell systems, we found that ATPase expression of this bacterium was markedly dependent upon air composition. It was interesting that cellular expression of $Ni^{2+}$- or $NH_4^{+}$-motive ATPases was significantly affected by extracellular pH, suggesting that these unique enzymes may physiologically be involved in cellular $Ni^2$ import and $NH_4^+$ export, respectively.

• Bulletin of the Korean Chemical Society
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• v.8 no.2
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• pp.79-83
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• 1987

The reduction of a series of 1-substituted benzyl-3-cyanoquinolinium ions (p-$cH_3$, H, p-Br, m-F, p-CN) by sodium borohydride has been investigated. In all cases the products from these reactions were found to be 1, 2-dihydroquinolines over 82% yields. Rates of reduction were measured in basic condition and in solvent system consisting of 4 parts of isopropyl alcohol and 1 part of water by volume. Second order rate constants were obtained for these reactions. When the ratio of [$OH^-$] to [$BH_4^-$] becomes large the observed rate constants ($K_{obs}$) decrease by a small factor. Reaction scheme and rate law are discussed. Bronsted ${\alpha}(=\frac{d\;In\;k}{d\;In\;K})$ obtained by using the value of equilibrium constant K, which was obtained previously, was not 0. Instead, a value of 0.36 was obtained which indicated that the reduction by borohydride was structure-dependent according to the Marcus formalism even though the reaction rate was close to the diffusion limit.

• Journal of Soil and Groundwater Environment
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• v.7 no.3
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• pp.95-102
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• 2002

Manganese oxide/ hydrogen peroxide($MnO_2$/${H_2}{O_2}$) reactions were investigated as an alternative to Fenton-like reaction to reduce chlorinated organic compounds in groundwater This system showed high degradation of CT with low ${H_2}{O_2}$concentration($\leq$294mM) at neutral condition, and CT degradation increased with increasing pH values. The rate of CT degradation was not so much dependent on increase in $MnO_2$concentration since increase in production of oxygen during the reaction obstructed reaction of ${H_2}{O_2}$ on the surface of $MnO_2$. These results show that $MnO_2$catalyzed Ponton-like reaction could be a potential alternative method for treating chlorinated organic compounds in groundwater.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.12
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• pp.1262-1267
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• 2008

Reductive discolorization studies were conducted. Azo-dyes usually have biological toxicity and it is known that the dyes are hardly removed by biological treatments. One of the simplest way to remove the color is to break the azo-bond and it is possible to break the bond with zero-valent metals. Three types of azo-dyes (Cibacron Briliant Yellow 3G-P (CBY3G-P), Benzopurpurin 4b (B-4B), Chicago sky blue 6b (CSB6B)) were tested. All tested azo-dyes were highly pH dependent and lower pH was preferred. The reaction mechanism was reductive cleavage and amines were expected as products. The dissolved iron ions from zero-valent iron can also remove the color through coagulation and precipitation and a set of experiments were conducted to evaluate the contribution by the dissolved iron. The results indicated that the contribution were also dependent on the type of dyes. This study showed that the reductive cleavage using zero-valent iron could be an alternative for the azo-dye waste water.