• KSBB Journal
• /
• v.23 no.5
• /
• pp.419-424
• /
• 2008

In this study, we examined the anti-diabetic activity in vitro by the crude extracts of Tetragonia tetragonioides which has been known to superior plants for the traditional prevention and treatment of stomach-related diseases. $\alpha$-Amylase and $\alpha$-glucosidase, the principal enzymes involved in the metabolism of carbohydrates, and aldose reductase, the key enzyme of the polyol pathway, have been shown to play the important roles in the complications associated with diabetes. A hexane (HX) fraction of T. tetragonioides were shown to inhibit more than 50% of salivary and pancreatin $\alpha$-amylase activity at concentration of 2.882 mg/mL and 2.043 mg/mL, respectively. In addition, the HX and ethylacetate (EA) fraction showed the highest inhibitory activity on yeast $\alpha$-glucosidase at values of $IC_{50}$ of 0.723 mg/mL and 1.356 mg/mL respectively. The HX, dichloromethane (DCM) and EA fraction showed more higher inhibitory activity on yeast $\alpha$-glucosidase than commercial agent such as 1-deoxynorjirimycin and acarbose. Also, the aldose reductase from human muscle cell had been inhibited strongly by the DCM fraction and HX fraction at 51.95% and 47.22% at a concentration of 1 mg/mL, respectively. Our study, for the first time, revealed the anti-diabetic potential of T. tetragonioides and this study could be used to develop medicinal preparations or nutraceutical and functional foods for diabetes and related symptoms.

• Korean Journal of Materials Research
• /
• v.22 no.9
• /
• pp.476-481
• /
• 2012

Among the various roll-to-roll printing technologies such as gravure, gravure-offset, and reverse offset printing, reverse offset printing has the advantage of fine patterning, with less than 5 ${\mu}m$ line width. However, it involves complex processes, consisting of 1) the coating process, 2) the off process, 3) the patterning process, and 4) the set process of the ink. Each process demands various ink properties, including viscosity, surface tension, stickiness, and adhesion with substrate or clich$\acute{e}$; these properties are critical factors for the printing quality of fine patterning. In this study, Ag nano ink was developed for reverse offset printing and the effect of polyvinylpyrrolidone(PVP), used as a capping agent of Ag nano particles, on the printing quality was investigated. Ag nano particles with a diameter of ~60 nm were synthesized using the conventional polyol synthesis process. Ethanol and ethylene glycol monopropyl ether(EGPE) were used together as the main solvent in order to control the drying and absorption of the solvents during the printing process. The rheological behavior, especially ink adhesion and stickiness, was controlled with washing processes that have an effect on the offset process and that played a critical role in the fine patterning. The electrical and thermal behaviors were analyzed according to the content of PVP in the Ag ink. Finally, an Ag mesh pattern with a line width of 10 ${\mu}m$ was printed using reverse offset printing; this printing showed an electrical resistivity of 36 ${\mu}{\Omega}{\cdot}cm$ after sintering at $200^{\circ}C$.

• Polymer(Korea)
• /
• v.29 no.2
• /
• pp.177-182
• /
• 2005

Montmorillonite (MMT) modified with siloxane diamine was reacted with a reactant obtained from 4,4'-diphenyl methane diisocyanate (MDI) and polyester type polyol, $Nippollan4010(\bar{M}_n2000)$. Finally, polyurethane (PU)/MMT composites were prepared by using 1,4-butane diol as a chain extender in $25\;wt\%$ solution of N,N-dimethyl acetamide (DMAc). It was expected that these nanocomposites had superior exfoliation property to that of MMT dispersed polyurethanes produced by simple mixing due to insertion of siloxane main chain to the silicate interlayer of MMT. Extent of reaction and formation of final products were analysed by using FT-IR spectroscopy. Dispersion into the PU and intercalation of MMT were identified by applying X-ray diffraction (XRD) and transmission electron microscopy (TEM). Tensile data were acquired by universal test machine (UTM). Thermal stability and variation of surface energy were characterized by thermal gravimetric analysis (TGA) method and measurement of contact angle on the synthesized composites, respectively. As the results the organo-MMT modified with siloxane diamine in the PU composites has an intercalated structure relatively well-expanded rather than a completely exfoliated structure. The tensile strengths and the moduli for the PU/organo-MMT composites were drastically enhanced in comparison to those of $PU/Na^+-MMT$ composites.

• Korean Journal of Soil Science and Fertilizer
• /
• v.37 no.1
• /
• pp.46-53
• /
• 2004

In this study, we compared the levels of methylotrophic bacterial community diversity in the leaf, stem, grain, root and rhizosphere soil sainples of four rice cultivars collected from three regions of Korea. Thirty five pigmented and five non-pigmented isolates showing characteristic growth on methanul were obtained. When phylotypes were defined by performing numerical analysis of 42 characteristics, four distinct clusters were formed. While two clusters, I and IV diverged on the basis of nitrate and nitrite reduction, other two clusters, comprising only pink pigmented colonies, diverged on the basis of cellulase activity. Out of the two reference strains used in the analysis, Methyhbacterium extorquens AM1 diverged from all the clusters and M. fujisawaense KACC 10744 grouped under cluster III. All the isolates were positive for urease, oxidase, catalase and pectinase activity and negative for indole production, MR and VP test, $H_2S$ production, starch, and casein hydrolysis. No clusters were found to possess thermotolerant isolates, as no growth of the isolates was observed at $45^{\circ}C$. Two strains in cluster I were found to possess gelatin hydrolysis and methane utilizing properties respectively. Most of the isolates in all the four clusters utilized monosaccliarides, disaccharide and polyols as carbon source. Six isolates showed considerable nitrogenase activity ranging from 86.2 to $809.9nmol\;C_2H_4\;h^{-1}\;mg^{-1}$ protein.

• Applied Chemistry for Engineering
• /
• v.16 no.3
• /
• pp.379-384
• /
• 2005

Polyurethane foams (PUFs) were prepared from polymeric 4,4'-diphenylmethane diisocyanate (PMDI), seven polyols with different functionalities and OH values, silicone surfactant, two catalysts, and three blowing agents. Chlorofluorocarbon (CFC-11), hydrochlorofluorocarbon (HCFC-141b) and hydrofluorocarbon (HFC-365mfc) were used as blowing agents. The effect of gelling and blowing catalysts on basic properties and cell structure of PUF with HCFC-141b was investigated. The cell size of the PUF decreased with an increase in the amount of catalyst from 0 to 2 pph (parts per hundred polyol). In the case of gelling type catalyst, the compressive strength increased from 11.9 to $12.66kg_f/cm^2$ with an increase in the amount catalyst from 0 to 2 pph but the density did not change significantly. The gelling time, density, and compressive strength of the PUF with three different blowing agents were measured. There was no detectable change in their properties. However, the cell structure of PUF with HCFC-141b was not uniform as in the other systems.

• Korean Chemical Engineering Research
• /
• v.53 no.6
• /
• pp.808-813
• /
• 2015

Boron is difficult to be removed from seawater by simple RO (reverse osmosis) membrane process, because the size of boric acid ($B(OH)_3$), the major form of aqueous boron, is as small as the nominal pore size of RO membrane. Thus, the complexation of boric acid with polyols was suggested as an alternative way to increase the size of aqueous boron compounds and the complexation behavior was investigated with Raman spectroscopy. As a reference, the Raman peak for symmetric B-O stretching vibrational mode both in boric acid and borate ion (${B(OH)_4}^-$) was selected. A Raman peak shift ($877cm^{-1}{\rightarrow}730cm^{-1}$) was observed to confirm that boric acid in water is converted to borate ion as the pH increases, which is also correctly predicted by frequency calculation. Meanwhile, the Raman peak of borate ion ($730cm^{-1}$) did not appear as the pH increased when polyols were applied into aqueous solution of boric acid, suggesting that the boric acid forms complexing compounds by combining with polyols.

• Elastomers and Composites
• /
• v.46 no.4
• /
• pp.343-351
• /
• 2011

We prepared polyurethane foam/cloisite30B/phosphates composites and characterized their rise time, density, cell morphology, and thermal properties. The composites were synthesized with polyadipatediol-cloisite30B composite (f=2.0), polyether-polyol (f=4.6), polymeric 4,4-diphenyl methane diisocyanate (f=2.5), and D-580 (phenyl polyoxyalkenyl phosphate). As a blowing agent, cyclopentane and distilled water were used at various concentrations of D-580 from 0 to 2.81 wt%. The rise times of PUF/Closite30B/Phosphate composites blown with distilled water were faster than those blown with cyclopentane by 30%. The composites blown with cyclopentane had spherical-shape cells and the cell diameter was decreased with increasing D-580 wt%. While $T_g$ of the composites blown with cyclopentane linearly decreased with increasing the D-580 content, the $T_g$ of the composites blown with distilled water increased with the D-580 content. All PUF/Closite30B/Phosphate composites began to decompose from $250^{\circ}C$. The composites blown with cyclopentane showed the second thermal decomposition at temperatures higher than $500^{\circ}C$. The thermal stability of all composites increased with the D-580 content. The effect of D-580 on the thermal stability of the composites was measured higher at the composites blown with distilled water.

• Polymer(Korea)
• /
• v.38 no.4
• /
• pp.441-448
• /
• 2014

Polyurethane/melamine phosphate composite foam (MP-PUF) was prepared from poly(adipate)diol/melamine phosphate composite (f=2), polyether-polyol (f=4.6), and PMDI (f=2.5). The thermal properties of MP-PUF such as morphology, closed-cell content, thermal conductivity, and thermal stabilities were characterized. Water was used as a blowing agent, and the composition of melamine phosphate (MP) was maintained at $1.43{\pm}0.3wt%$ of MP-PUF. As the content of water increased, the thermal conductivity of pure polyurethane foam (PUF) decreased, whereas the thermal conductivity of MP-PUF increased. The thermal stabilities of the PUF and the MP-PUF were maximized at 5 php $H_2O$, and then decreased at the higher $H_2O$ contents. The thermal stabilities of MP-PUF were greatly enhanced due to the synergetic effect of MP and urea, which was generated during the blowing process. The temperature of 50% residual mass of MP-PUF increased to $370{\sim}450^{\circ}C$ and the temperature of 30% residual mass exceeded over $700^{\circ}C$. Compared to the PUF, the temperature of 50% residual mass and 30% residual mass were higher than 25 and $70^{\circ}C$, respectively.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.10 no.3
• /
• pp.71-81
• /
• 1986

In order to control the formaldehyde release from D.P. finished fabric, cotton fabric was padded in DMDHEU resin bath containing either $Zn(NO_3)_2$ or $MgCl_2$ catalyst and a form-aldehyde scavenger like Glycerol, Sorbitol, Formamide, Polyvinyl alcohol (PVA, n= 2000) or diols, then dried and cured. The results are as follows : 1. When Lewis acid catalyst like $Zn(NO_3)_2$ or $MgCl_2$ was added in pad bath, the fabric finished with $Zn(NO_3)_2$ catalyst released the lower formaldehyde than with $MgCl_2$. 2. When the effect of pad bath pH was examined with varying the kinds of catalyst and the scavenger, it was found that the pad bath pH influenced on the amount of formaldehyde release and the optimum pad bath pH is at 4.3. Especially, in case of finishing at pad bath pH 4.3 with adding Formamide, the amount of formaldehyde release was decreased by about $45\~$35\%$ with $Zn(NO_3)_2$, while by about $20\~$45\%$ with $MgCl_2$ catalyst. In case of varying the concentration of a scavenger (Formamide), $1\%$ concentration of a scavenger was found to be the optimum level ana the higher the curing temperature up to $180^{\circ}C$, the lesser the amount of formaldehyde release were observed. 3. When the diol was used as scavenger, the amount of formaldehyde release was decreased by about $40\~$50\%$, but the longer the intramolecular length between OH groups, the lessor the amount of decrease of formaldehyde release were observed. 4. When the mixture of scavengers (Formamide and Glycerol) was added in the pad bath, .synergistic effect on formaldehyde release between the two scavengers wasn't observed. 5. The tensile strength of the resin finished fabric was reduced with increasing the pad lath pH and was influenced by the kind of scavengers, and the tensile strength was severely reduced when scavengers, especially Formamide, was added. The wrinkle recovery property is generally improved by resin finish on cotton fabric. When Formamide was added, the wrinkle recovery property is slightly decreased compared with that of the fabrics resin finished without a scavenger, and when polyol was added, the wrinkle recovery property showed almost no change.

• Applied Chemistry for Engineering
• /
• v.24 no.3
• /
• pp.305-313
• /
• 2013

In this study, we investigated effects of thermal annealing on the thermal properties and microphase separation behaviors of glycidyl azide-based thermoplastic polyurethane elastomers (ETPE). The GAP-based ETPEs were characterized by attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimeter (DSC), dynamic mechanical analysis (DMA), and gel permeation chromatography (GPC). The effects of annealing temperature conditions ($80{\sim}130^{\circ}C$, 1 h or 24 h) on the properties of the ETPEs were investigated. The intensity of azide group absorption peak of ATR-FTIR spectra and the solubility of ETPE for methylene chloride and dimethylformamide solvent decreased after the annealing at $130^{\circ}C$ for 1 h and at $105^{\circ}C$ for 24 h. With increasing the annealing temperature from $80^{\circ}C$ to $110^{\circ}C$, the high temperature rubbery plateau region of storage modulus curves from DMA thermogram for GAP-based ETPEs was extended to the higher temperature.