• Korea-Australia Rheology Journal
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• v.20 no.3
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• pp.109-116
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• 2008

The effect of intermolecular aggregation induced by hydrophobic and electrostatic interactions on shear and elongational flow properties of aqueous acrylic thickener solutions is discussed. Complex shear modulus is determined at frequencies up to $10^4$ rad/s employing oscillatory squeeze flow. Extensional flow behavior is characterized using Capillary Break-up Extensional Rheometry. Aqueous solutions of poly(acrylic acid)(PAA)/poly(vinylpyrrolidone-co-vinylimidazole) (PVP-VI) mixtures exhibit unusual rheological properties described here for the first time. Zero-shear viscosity of the mixtures increases with decreasing pH and can exceed that of the pure polymers in solution by more than two orders of magnitude. This is attributed to the formation of complexes induced by electrostatic interactions in the pH range, where both polymers are oppositely charged. PAA/PVP-VI mixtures are compared to the commercial thickener Sterocoll FD (BASF SE), which is a statistical co-polymer including (meth) acrylic acid and ethylacrylate (EA) forming aggregates in solution due to "sticky" contacts among hydrophobic EA-sequences. PAA/PVP-VI complexes are less compact and more deformable than the hydrophobic Sterocoll FD aggregates. Solutions of PAA/PVP-VI exhibit a higher zero-shear viscosity even at lower molecular weight of the aggregates, but are strongly shear-thinning in contrast to the weakly shear-thinning solutions of Sterocoll FD. The higher ratio of characteristic relaxation times in shear and elongation determined for PAA/PVP-VI compared to Sterocoll FD solutions reflects, that the charge-induced complexes provide a much stronger resistance to extensional flow than the aggregates formed by hydrophobic interactions. This is most likely due to a break-up of the latter in extensional flow, while there is no evidence for a break-up of complexes for PAA/PVP-VI mixtures. These flexible aggregates are more suitable for the stabilization of thin filaments in extensional flows.

• Korean Journal of Environmental Agriculture
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• v.37 no.2
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• pp.87-96
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• 2018

BACKGROUND: The vigorous shoot growth in upper part of apple tree canopy leads to poor fruit quality and flower bud formation in lower part of canopy. So, this study was conducted to develop the proper control method about the shoot growth in upper part of apple tree canopy. METHODS AND RESULTS: Trunks of 'Fuji'/M9 apple trees were cut (back pruned) to 2.5 m in tree height on 11 February (dormant) or 12 April (full bloom). Naphthalene acetic acid (NAA) was applied at 2.0% to cut surface when trunk was pruned. Prohexadione-calcium (Pro-Ca) was sprayed at 250 mg/L above 2.0 m in tree height at 23 April (petal fall). The NAA or Pro-Ca application after trunk was pruned at dormant (TR-2 and TR-3) significantly reduced shoot growth in upper part of canopy compared with the control (tree was only pruned at dormant, TR-1), but the percent of shoots showing the secondary growth of TR-3 was higher over 2 times than that of TR-2. The reduction of shoot growth in upper part of canopy by TR-2 and TR-3 increased the fruit red color from the lower part in the treating year and blooming of the lower part in the following year. CONCLUSION: Applying 2.0% NAA to cut surface of pruned apple trunk at dormant was the most effective way for stabilization of the tree vigor in upper part of the canopy in a high density apple orchard.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.23
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• pp.10151-10156
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• 2015

4-Hydroxynonenal (4-HNE) is a stable end product of lipid peroxidation, which has been shown to play an important role in cell signal transduction, while increasing cell growth and differentiation. 4-HNE could inhibit phosphatase and tensin homolog (PTEN) activity in hepatocytes and increased levels have been found in human invasive breast cancer. Here we report that 4-HNE increased the cell growth of breast cancer cells as revealed by colony formation assay. Moreover, vascular endothelial growth factor (VEGF) expression was elevated, while protein levels of hypoxia inducible factor 1 alpha (HIF-$1{\alpha}$) were up-regulated. Sirtuin-3 (SIRT3), a major mitochondria NAD+-dependent deacetylase, is reported to destabilize HIF-$1{\alpha}$. Here, 4-HNE could inhibit the deacetylase activity of SIRT3 by thiol-specific modification. We further demonstrated that the regulation by 4-HNE of levels of HIF-$1{\alpha}$ and VEGF depends on SIRT3. Consistent with this, 4-HNE could not increase the cell growth in SIRT3 knockdown breast cancer cells. Additionally, 4-HNE promoted angiogenesis and invasion of breast cancer cells in a SIRT3-dependent manner. In conclusion, we propose that 4-HNE promotes growth, invasion and angiogenesis of breast cancer cells through the SIRT3-HIF-$1{\alpha}$-VEGF axis.

• YAKHAK HOEJI
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• v.54 no.6
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• pp.529-534
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• 2010

Alzheimer's disease (AD) is characterized pathologically by the presence of intracellular neurofibrillary tangles and deposition of ${\beta}$-amyloid ($A{\beta}$) peptides, which are generated by processing of amyloid precursor protein (APP). It is urgent to develop effective therapies for the treatment of AD, since our society rapidly accelerate aging. $A{\beta}$ peptides have been believed to be neurotoxic and now are also considered to have effects on the mechanism of memory formation. Recently, we investigated that a quinoline compound from natural product reduced the secretion of $A{\beta}$ from the neuroblastoma N2a cells (NL/N cell line) overexpressing APPswe. In this study, 3-phenyl-1-isoquinolinamine, a synthetic isoquinoline compound was analyzed to determine its effects on the metabolism of APP. It inhibited the secretion of $A{\beta}$ peptides from the N2a NL/N cell line. Beta-site APP cleaving enzyme (BACE) fluorescence resonance energy transfer (FRET) assay revealed that it inhibited BACE activity in a dose dependent manner. Immunoblotting study showed that it inhibited APP stabilization and expression and it slightly increased the stablization and the expression of ${\gamma}$-secreatase component from the N2a NL/N cell line. We suggest that 3-phenyl-1-isoquinolinamine inhibits APP metabolism and $A{\beta}$ generation by the means of BACE inhibitory mechanism. This is the first report that 3-phenyl-1-isoquinolinamine inhibits the secretion of $A{\beta}$ peptides from neuroblastoma cells.

• Journal of the Korean Chemical Society
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• v.40 no.3
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• pp.187-195
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• 1996

Ab initio SCF calculations have been carried out for the five conceivable trimers formed between one hydrogen cyanide and two hydrogen fluorides using a basis set of TZ＋P quality. Several ground state properties of these trimeric complexes have been evaluated, and compared with those of isolated monomers and appropriate dimers. Computed equilibrium geometries, stabilization energies, and dipole moments are given in order to suppliment the available experimental data. At this level of approximation, intramolecular bond distances are consistently shorter than experimental ones. However, intermolecular distances upon complex formation, and dipole moments are overestimated compared with experimental ones. HCN$(HF)_2$ trimer appears to be the most favourable among the five kinds of trimer complex, and also more stable than $(HCN)_2HF$. The typical features of the non-additivity of intermolecular interaction are relatively strong in the HCN$(HF)_2$ trimer.

• The Journal of Advanced Prosthodontics
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• v.1 no.1
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• pp.47-55
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• 2009

STATEMENT OF PROBLEM. A few of studies which compared and continuously measured the stability of various surface treated implants in the same individual had been performed. PURPOSE. We aim to find the clinical significance of surface treatments by observing the differences in the stabilization stages of implant stability. MATERIAL AND METHODS. Eight different surface topographies of dental implants were especially designed for the present study. Machined surface implants were used as a control group. 4 nano-treated surface implants(20 nm $TiO_2$ coating surface, heat-treated 80 nm $TiO_2$ coating surface, CaP coating surface, heat treated CaP coating surface) and 3 micro-treated surface implants [resorbable blast media(RBM) surface, sandblast and acid-etched(SAE) surface, anodized RBM surface] were used as experiment groups. All 24 implants were placed in 3 adult dogs. $Periotest^{(R)}$ & ISQ values measured for 8 weeks and all animals were sacrificed at 8 weeks after surgery. Then the histological analyses were done. RESULTS. In PTV, all implants were stabilized except 1 failed implants. In ISQ values, The lowest stability was observed at different times for each individual. The ISQ values were showed increased tendency after 5 weeks in every groups. After 4 to 5 weeks, the values were stabilized. There was no statistical correlation between the ISQ values and PTV. In the histological findings, the bone formation was observed to be adequate in general and no differences among the 8 surface treated implants. CONCLUSIONS. In this study, the difference in the stability of the implants was determined not by the differences in the surface treatment but by the individual specificity.

• Korean Journal of Metals and Materials
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• v.46 no.12
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• pp.771-779
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• 2008

An effective way of increasing the strength and fracture toughness of reactor pressure vessel steels is to change the material specification from that of Mn-Mo-Ni low alloy steel(SA508 Gr.3) to Ni-Mo-Cr low alloy steel(SA508 Gr.4N). In this study, we evaluate the effects of alloying elements on the microstructural characteristics of Ni-Mo-Cr low alloy steel. The changes in the stable phase of the SA508 Gr.4N low alloy steel with alloying elements were evaluated by means of a thermodynamic calculation conducted with the software ThermoCalc. The changes were then compared with the observed microstructural results. The calculation of Ni-Mo-Cr low alloy steels confirms that the ferrite formation temperature decreases as the Ni content increases because of the austenite stabilization effect. Consequently, in the microscopic observation, the lath martensitic structure becomes finer as the Ni content increases. However, Ni does not affect the carbide phases such as $M_{23}C_6 $ and $M_7C_3$. When the Cr content decreases, the carbide phases become unstable and carbide coarsening can be observed. With an increase in the Mo content, the $M_2C$ phase becomes stable instead of the $M_7C_3$ phase. This behavior is also observed in TEM. From the calculation results and the observation results of the microstructure, the thermodynamic calculation can be used to predict the precipitation behavior.

• Applied Chemistry for Engineering
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• v.21 no.1
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• pp.40-45
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• 2010

Entrapment of hydrophobic flavonoid luteolin into ethosome was carried out for improving its stability and making practical application in the field of drug and cosmetics. The formation of liquid crystalline phase and its thermal properties were investigated by polarized optical microscopy and DSC. The phase inversion from W/O to W/O/W was detected by conductivity change with the addition of PBS buffer solution into the ethanol-dissolved lecithin mixture. The particle size change of ethosome with constituent composition was examined, which showed that the incorporation of luteolin into lecithin up to 10% had little effect on the size of ethosome. Enhancement of stability of luteolin by entrapment into ethosome was verified through DPPH test. The stabilization efficacy of ethosome was improved further by the addition of tocopherol.

• Resources Recycling
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• v.18 no.3
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• pp.36-41
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• 2009

The objectives of this study are focusing on the issue with efficiently recycling for EAF slag as construction material such as an aggregate of concrete. This study can be classified mainly into two categories: the first section is the carbonation treatment of Electric Arc Furnace(EAF)-slag for obtaining soundness as using aggregate of concrete. And the second section is the application of carbonated EAF-slag on the mortar test to evaluate the stability and mechanical property, which is compressive strength, according to the replacement of EAF-slag on the mortar. It was known that pH of EAF-Slagle according to carbonation time decreases drastically to 7 within several sec of carbonation, and a calcite is formed on the surface of EAF slag. The formation of calcite during the carbonation process of EAF slag lead to fill at pore in the texture of EAF-Slag surface, and than the porosity of EAF-slag decreases with carbonation process. In the mortar test, compressive strength, according to the replacement of EAF-Slag to sand on the mortar, the compressive strength of mortar increased as the 50% replacement ratio of EAF slag for sand was above 10% higher than that of reference mortar according to 50% replacement of EAF slag.

• Journal of Pharmaceutical Investigation
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• v.25 no.1
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• pp.9-17
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• 1995

To stabilize omeprazole(OMP), ethylenediamine(ED) complex of omeprazole(OMPED) was prepared by reaction between OMP and ED in methanol, and the complex formation was confirmed by the instrumental analysis, i.e., IR, DSC, EA, NMR, MS and XRD. The rates of decomposition of OMP and OMPED in aqueous solution and the shelf lives at standard temperature were measured by accelerated stability analysis. The results are summarized as follows; The mole ratio of OMP and ED in OMPED complex is 1:1, the energy of formation within OMPED might be combined between polar imidazole group of OMP with induced a dipole amine group in the readily polarizable ED molecule. At standard temperature the degradation rate constant of OMP in aqueous solution is $2.540{\times}10^{-2}\;hr^{-1}$ and the shelf life is 4.15 hrs, and in the case of OMPED the degradation rate constant is $7.986{\times}10^{-4}\;hr^{-1}$ and the shelf life is 131.96 hrs. So, the OMPED has about 31 times longer shelf life than OMP. The activation energy of OMP and OMPED are 5.23 and 18.55 kcal $mole^{-1}$ respectively. The stability of OMP is dependent chiefly on pH in the solutions and it decomposes readily in acidic medium by hydrogen ion catalized reaction but becomes stable beyond pH 9.0. In case of the ED-complex, OMPED is stable in neutral as well as in dilute acidic solutions even in pH 6, OMPED is very stable to light(UV), that is, the rate constant and shelf life of OMP are $k=1.0188{\times}10^{-2}\;day^{-1}$, $T_{90%}=4.5 \;days$, on the other hand, the those of OMPED are $k=7.138{\times}10^{-4}\;day^{-1}$, $T_{90%}=64.1\;days$, respectively. From the above results, it is thought that new dosage forms could be developed by using the OMPED as a potential OMP complex.