• Bulletin of the Korean Chemical Society
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• v.24 no.6
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• pp.763-770
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• 2003

The $BH_5$ molecule, which is suggested as an intermediate of the acidolysis of $BH_4^-$, contains a weak two-electron-three-center bond and it requires extremely high-level of theories to calculate the energy and structure correctly. The structures and energies of $BH_5$ and the transition state for the hydrogen scrambling have been studied using recently developed multi-coefficient correlated quantum mechanical methods (MCCMs). The dissociation energies and the barrier heights agree very well with the previous results at the CCSD(T)/ TZ(3d1f1g, 2p1d) level. We have also calculated the potential energy curves for the dissociation of $BH_5$ to $BH_3$ and $H_2$. The lower levels of theory were unable to plot correct potential curves, whereas the MCCM methods give very good potential energy curves and requires much less computing resources than the CCSD(T)/ TZ(3d1f1g,2p1d) level. The potential energy of the $BH_5$ scrambling has been obtained by the multiconfiguration molecular mechanics algorithm (MCMM), and the rates are calculated using the variational transition state theory including multidimensional tunneling approximation. The rate constant at 300 K is 2.1 × $10^9s^{-1}$, and tunneling is very important.

• Journal of Korean Society of Forest Science
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• v.89 no.2
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• pp.198-207
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• 2000

The diurnal and seasonal changes of water potential and stomatal diffusive resistance were investigated with the effects of shade treatment to elucidate the water relations of the one year old seedlings of Betula platyphylla var. japonica, Zelkova serrata, Acer mono, and Prunus sargentii subjected to five levels of artificial shade treatments from full sun to nearly full shading of 2-6% relative light transmittance. Stomatal diffusive resistance measured in the four deciduous hardwood species studied changed variously by growing season and by species with the five shade treatments in the ranges of 1.7~25.1s/cm in 9 a.m., 2.3~33.3s/cm in 1 p.m., and 1.1~36.8s/cm in 5 p.m.. The measurements of stomatal diffusive resistance increased with increasing the shading, and were higher in September than in June or July in most of the species studied. The stomatal diffusive resistance measured in Zelkova serrata, Acer mono, and Prunus sargentii seemed to be approximately 3~4 times higher in nearly full shading treatment than in full sun. Water potential also changed variously by growing season and by species with five different shade treatments in the ranges of -0.17~-1.20MPa in 9 a. m., -0.30~-2.03MPa in 1 p. m., and -0.18~-1.34MPa in 5 p.m., respectively. On the reverse of stomatal diffusive resistance, the measurements of water potential were lower in September than in June or July in most of the species studied, and the seasonal differences were especially greater in Zelkova serrata comparing with the other species. The water potential seemed to be higher of approximately 2~3 times in nearly full shading treatment than in full sun in all of the species studied, but the differences among the shading treatments were less in water potential than in stomatal diffusive resistance. The differences of water potential following the gradient of five shading treatment seemed to be less in Betula platyphylla var. japonica than in the other species. In Acer mono and Prunus sargentii being some shade tolerant species, the water potential increased rapidly through about noontime with raising the shading level from full sun to the intermediate shading level of 22-28% relative light transmittance, but slowly with closing to full shading. In Betula platyphylla var. japonica and Zelkova serrata being shade intolerant species, the water potential increased gradually throughout the shading levels and the increment ranges were greater in Zelkova serrata than in Betula platyphylla var. japonica.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.1
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• pp.119-123
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• 2009

In vitro acid- and bile-tolerant lactic acid bacteria isolated and identified from Indonesian traditional fermented milk dadih might be considered as potential probiotic strains after further characterization with animal models, especially for their therapeutic properties. Five dadih lactic bacteria isolates each had moderate survival rate for 2 h at pH 2.0, as well as bile tolerance. The aim of this research was to identify candidate probiotic lactic bacteria among indigenous dadih lactic isolates originated from Bukit Tinggi, West Sumatra, especially their in vivo antimutagenic property. Milk cultured with Enterococcus faecium IS-27526 significantly lowered fecal mutagenicity of rats as compared to the control group, skim milk, and milk cultured with L. plantarum IS-20506. These results suggest that Enterococcus faecium IS-27526 may serve as a potential probiotic strain with its antimutagenicity.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2001.05a
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• pp.236-237
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• 2001

In this study, experiments were carried out to measure the variations in the corrosion potential and current density of polarization curves with amorphous $Fe_{70}Cr_5Si_{10}B_{15}$ and $Co_{70}Cr_5Si_{10}B_{15}$ alloy ribbon. The results were particularly examined to identify the influences of corrosion potential including various conditions such as hydrochloric acid, temperature, salt, pH, and oxygen. The optimum conditions were established with variations including temperature, salt, pH, oxygen, corrosion rate, and resistance of corrosion potential. The mass tranfer coefficient(${\alpha}$) value was determined with the Tafel's slope for the anodic dissolution based on the polarization effect with optimum conditions. The second anodic current density peak and maximum passive current density were designated as the critical corrosion sensitivity($I_{r}/I_{f}$).

• Journal of Microbiology
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• v.45 no.6
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• pp.534-540
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• 2007

The Streptomyces coelicolor A3(2) genome contains six operons (rrnA to F) for ribosomal RNA synthesis. Transcription from rrnD occurs from four promoters (p1 to p4). We found that transcripts from the p1 and p3 promoters were most abundant in vivo in the early exponential phase. However, at later phases of exponential and stationary growth, transcripts from the p1 promoter decreased drastically, with the p3 and p4 transcripts constituting the major forms. Partially purified RNA polymerase supported transcription from the p3 and p4 promoters, whereas pure reconstituted RNA polymerase with core enzyme (E) and the major vegetative sigma factor ${\sigma}^{HrdB}$ ($E{\cdot}{\sigma}^{HrdB}$) did not. In order to assess any potential requirement for additional factor(s) that allow transcription from the p3 and p4 promoters, we fractionated a partially purified RNA polymerase preparation by denaturing gel filtration chromatography. We found that transcription from the p3 and p4 promoters required factor(s) of about 30-35 kDa in addition to RNAP holoenzyme ($E{\cdot}{\sigma}^{HrdB}$). Therefore, transcription from the p3 and p4 promoters, which contain a consensus -10 region but no -35 for ${\sigma}^{HrdB}$ recognition, are likely to be regulated by transcription factor(s) that modulate RNA polymerase holoenzyme activity in S. coelicolor.

• Biomolecules & Therapeutics
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• v.14 no.1
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• pp.25-29
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• 2006

We tested effects of bioactive lysophospholipids including lysophosphatidic acid (LPA), lysophosphatidylcholine (LPC), sphingosylphosphorylcholine (SPC), and sphingosine I-phosphate (S1P) on membrane potential in C6 glioma cells to understand action mechanism of the lysophospholipids. Membrane potential was estimated by measuring fluorescence change of DiBAC-loaded glioma cells. LPA largely increased membrane potential and the increase was gradually diminished. LPC also increased the membrane potential, however, the increase sustained. SPC induced smaller increase of membrane potential than LPC. SIP was not able to change the membrane potential. We tested effects of suramin and pertussis toxin on lysophospholipid-induced membrane potential increase. However, there wasn't any effect. The membrane potential increase was partially diminished in $Na^+$-free media, suggesting $Na^+$ influx as a component of membrane potential changes. Thus, involvement of $Na^+$ influx in the increase of membrane potential by lysophospholipids and independence of suramin-sensitive GPCRs and pertussis toxin-sensitive G proteins are found in this study.

• Elastomers and Composites
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• v.50 no.4
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• pp.304-313
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• 2015

In this study, the anionic emulsified asphalt was prepared by dispersing asphalt particles evenly into water with combination of anionic and nonionic surfactants. Effects of NaOH and $CaCl_2$ on the phase stability of the emulsified asphalt were also investigated through zeta potential value and rheology behavior; the emulsified asphalt added with NaOH and $CaCl_2$ showed higher zeta potential value than that the asphalt with addition of only anionic and nonionic surfactants. In addition, with regard to shear thinning behaviors, it was found that pH of the emulsified anionic asphalt and $Ca^{2+}$, counter ion, affected the phase stability. SBR (styrene-butadiene-rubber) latex, EPD (water dispersed Epoxy), PU (polyurethane) and RI-10S, SBS (styrene-butadiene-styrene)-based property improvement additive, were used and studied to enhance the adhesion properties with the aggregates. RI-10S, however, was found to be only compatible with the anionic emulsified asphalt; the coating rate, adhesion and compression strength were increased with the RI-10S content.

• Biomolecules & Therapeutics
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• v.29 no.4
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• pp.373-383
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• 2021

Atherosclerosis is the deposition of plaque in the main arteries. It is an inflammatory condition involving the accumulation of macrophages and various lipids (low-density lipoprotein [LDL] cholesterol, ceramide, S1P). Moreover, endothelial cells, macrophages, leukocytes, and smooth muscle cells are the major players in the atherogenic process. Sphingolipids are now emerging as important regulators in various pathophysiological processes, including the atherogenic process. Various sphingolipids exist, such as the ceramides, ceramide-1-phosphate, sphingosine, sphinganine, sphingosine-1-phosphate (S1P), sphingomyelin, and hundreds of glycosphingolipids. Among these, ceramides, glycosphingolipids, and S1P play important roles in the atherogenic processes. The atherosclerotic plaque consists of higher amounts of ceramide, glycosphingolipids, and sphingomyelin. The inhibition of the de novo ceramide biosynthesis reduces the development of atherosclerosis. S1P regulates atherogenesis via binding to the S1P receptor (S1PR). Among the five S1PRs (S1PR1-5), S1PR1 and S1PR3 mainly exert anti-atherosclerotic properties. This review mainly focuses on the effects of ceramide and S1P via the S1PR in the development of atherosclerosis. Moreover, it discusses the recent findings and potential therapeutic implications in atherosclerosis.

• Journal of dental hygiene science
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• v.23 no.1
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• pp.51-59
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• 2023

Background: Tea tree oil has antiviral, antimicrobial and antifungal effects and Mastic oil has antifungal and anticancer effects. For synergistic effects of oils, blending oil containing a mixture of two to three oils is recommended. This study aimed to determine the antibacterial effects of Tea tree oil, Mastic oil, and Blending oil containing the two oils in a mixture, to verify and suggest the potential use of these oils as a substance to prevent dental caries. Methods: Tea tree oil, Mastic oil, and Blending oil with a 1:1 blend of the two oils were diluted in liquid medium to 0% (negative control), 0.5%, 1.0%, and 2.0%. Streptococcus mutans was applied to each experimental group of the three diluted oils and after 8 h culture, the optical density (OD) was measured and the growth inhibition rate for S. mutans was estimated. Results: Tea tree oil had significantly low OD values across all concentrations (p<0.05) without significant variation among different concentrations (p>0.05). Mastic oil did not significantly vary in OD compared to the negative control across all concentrations (p>0.05) without significant variation among different concentrations (p>0.05). Blending oil, compared to the negative control, did not significantly vary in OD at 0.5% (p>0.05) but significant variation was found as the concentration increased (p<0.05). Additionally, for Tea tree oil and Mastic oil, the growth inhibition rate showed no significant variation according to concentration (p>0.05), whereas for Blending oil, the growth inhibition rate for S. mutans showed a significant difference at 1.0% (p<0.05) and at higher concentrations. Conclusion: Blending oil containing a Tea tree oil and Mastic oil demonstrated a significant growth inhibition effect on S. mutans from the concentration of 1.0%, which suggested its potential use as an effective antibacterial agent for dental caries.

• Archives of Pharmacal Research
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• v.13 no.1
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• pp.19-23
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• 1990

A series of hexahydro-s-triazine derivative were prepard. Cytotoxic activity testing using mouse leukemia cells (p 388) and antimicrobial testing indicated that the compounds which contain isoxazolyl moiety higher activity than those containing other hetercyclic moieties.