• The Journal of Natural Sciences
• /
• v.8 no.2
• /
• pp.169-173
• /
• 1996

This experiment was conducted to investigate the effect of ethylene adsorbent removing ethylene gas produced from apple fruits in poly ethylene film bag storage. The treatment of ethylene adsorbent was not effected the change in soluble solids and organic acid content of fruits. The fruit softening was remarkably delayed by the absorbent treatment, and the more amount of it was the more effective. The ethylene evolution and respiration of fruits reduced or decreased by this treatment during storage. The ethylene adsorbent for 'Fuji' apple fruit was effective more than 30g per 10kg fruits.

• Proceedings of the KOSOMBE Conference
• /
• v.1996 no.11
• /
• pp.327-330
• /
• 1996

Poly(L-leucine)(PLL)/poly(ethylene oxide)(PEO)/poly (L-leucine)(PLL) block copolymers were synthsized by polymerization of L-leucine N-carboxyanhydride with diamine-terminated PEO for possibility of wound dressing which may have several advantages such as 1) increase of solubility, 2) control of biodegradation, 3) absorption of body fluid. 4) non-immunogenic effect than PLL homopolymer wound dressing aleady commercialized. Water content increased with an increase of PEO content in the block copolymer due to the hydrophilicity of PEO. Release of silver sulfadiazine(AgSD) from AgSD loaded wound dressing increased with an increase of PEO content in the block copolymer. It was found that the number of Pseudomonas aeruginosa decrease with an increase of PEO content due to the fast release of antibacterial agents with an increase of PEO content in the block copolymer.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.30 no.3
• /
• pp.236-244
• /
• 1985

To know the varietal differences of ethylene evolution, 55 rice varieties were tested at seedling stage. And, also, 6 rice varieties were tested the biosynthesis of ethylene production. The group of japonica varieties produced higher amount of ethylene than the indica and indica x japonica crossed varieties. The content of ACC in rice seedlings of japonica varieties was higher than in seedlings of indica and indica x japonica varieties. And, also, the conversion rate of mathionine and ACC to ethylene in seedling of japonica varieties was higher than in seedling of indica and indica x japonica varieties.

• Journal of Plant Biology
• /
• v.37 no.4
• /
• pp.445-452
• /
• 1994

Effects of methyl jasmonate (MeJA) on ethylene production in mungbean (Phaseolus radiatus L.) hypocotyl and leaf segments were studied. Ethylene production in mungbean hypocotyl segments was decreased in proportion to MeJA concentrations and $450\;\mu\textrm{M}$ of MeJA showed 50% inhibitory effect. This inhibitory effect appeared after 3 h of incubation period and continued for 24 h. Inhibition of ethylene production by MeJA was due to the decrease in 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase activity. However, MeJA treatment had no effect on ACC content and ACC synthase activity. MeJA also inhibited auxin-induced ethylene production in hypocotyls. To investigate the mechanisms of the inhibitory effect of MeJA on the auxin-induced ethylene production, ACC synthase and ACC oxidase activity were examined after MeJA treatment. MeJA decreased the ACC content and ACC synthase activity as weD as ACC oxidase activity in the auxin-treated tissue. These results suggest that the inhibition of MeJA on auxin-induced ethylene production is not due to the direct inhibitory effect of MeJA on the ACC synthase, but to the inhibition of the ability of IAA to promote the synthesis of ACC synthase. In contrast, ethylene production from the detached mungbean leaves was stimulated by MeJA. The rate of ethylene production increased approximately 65% over the control after 12 h of incubation period by $4.5\;\mu\textrm{M}$ MeJA. When MeJA was applied to detached leaves along with IAA, the effect of MeJA appeared to be additive. In an effort to elucidate mechanisms of MeJA action on auxin-induced ethylene production in the leaf tissue, enzyme activities of ACC synthase and ACC oxidase were examined. MeJA stimulated ACC oxidase activity but did not affect ACC synthase activity in leaf tissue. Together, these results suggest that MeJA plays different roles in the ethylene production in the different mungbean tissues.issues.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1995.05a
• /
• pp.115-119
• /
• 1995

Electrical conduction characteristics of Polyethylene/Ethylene vinyl acetate blends of varing vinyl acetate content(1% and 4%) were investigated at electric fields ranging from 10$\^$6/ to 10.$\^$8/ V/cm over the temperature range of 30 and 85$^{\circ}C$. It was obser-ved that the extent of current density was changed at the blends and the rate of change of current den-sity was slightly suppressed at high field range, but PE and EVA were not shown. The change of con-duction characteristics and a suppression in rate of change of current density were attributed to the VA content in PE.EVA blends.

• Polymer(Korea)
• /
• v.38 no.3
• /
• pp.307-313
• /
• 2014

The physical properties of functionalized graphene sheet (FGS)/poly(ethylene-co-vinyl acetate) (EVA) was examined with various kinds of EVA, having vinyl acetate (VA) contents in the range of 0 to 40 wt%. The compatibility between FGS and EVA was enhanced as the polar VA content of EVA increased. Thus, the dispersion of FGS in EVA became finer, and the decrease of surface resistivity and the increase of tensile modulus by the added FGS became more effective when the VA content of EVA was high. When the VA content was low, the elongation at break was reduced drastically by added FGS due to the poor adhesion of FGS/EVA interface. The crystallization of EVA was generally retarded by the interaction with dispersed FGS. However, when both the VA content of EVA and the added amount of FGS were low, the crystallization of EVA was enhanced, probably due to the predominant nucleating effect by FGS.

• Elastomers and Composites
• /
• v.56 no.2
• /
• pp.92-99
• /
• 2021

Microstructure-dependent changes in the crystalline properties of poly(ethylene-co-vinyl acetate) (EVA) was investigated using various EVAs at different VA contents via X-ray diffraction (XRD). The parameters analyzed herein were percentage crystallinity (X_c), interplanar crystal spacing (d_hkl), crystal stack size (D_hkl), and the number of crystal plane piles (N_hkl). The X_cs of [110] and [200] crystals were 21.0-4.1 and 6.7-1.4%, respectively, and they decreased by approximately 2.3 and 0.7% for every mol% of the VA content, respectively. The X_c ratios of the [110] and [200] crystals were approximately 3. The d₁₁₀s and d₂₀₀s values were 0.41-0.42 and 0.37-0.38 nm, respectively. The D₁₁₀s and D₂₀₀s values were 9.56 -21.92 and 7.00-16.42 nm, respectively. The d_hkls increased with an increase in the VA content, whereas the D_hkls decreased. The N₁₁₀s and N₂₀₀s were 22.7-51.3 and 18.3-43.2, respectively, and they decreased by increasing the VA content. EVA with the same VA content showed different crystalline properties as per the suppliers, and some EVAs deviated from the average trends. This could be explained by the difference in their microstructures such as the sizes and distribution uniformity of the ethylene sequences in EVA chains.

• Membrane Journal
• /
• v.27 no.2
• /
• pp.147-153
• /
• 2017

In this study, we investigated permeation properties of single gas ($N_2$, $O_2$, $CO_2$) through membranes composed of poly(ethylene oxide) (PEO) and poly(ethylene-co-vinyl acetate) (EVA) blend. The prepared membranes showed no new absorbance peaks, which indicate the physical blending of PEO and EVA by FT-IR analysis. SEM observation showed that the crystalline phase of PEO decreased with increasing EVA content in the PEO/EVA mixed matrix. DSC analysis showed that the crystallinity of the PEO/EVA blend membrane decreased with increasing EVA content. Gas permeation experiment was performed with various feed pressure (4~8 bar). The permeability increased in the following order: $N_2$ < $O_2$ < $CO_2$. The permeability of $CO_2$ in PEO/EVA blend membranes were increased with increasing feed pressure, However, the permeability of $N_2$ and $O_2$ were independent of feed pressure. On the other hand, the permeability of all the gases in PEO/EVA blend membranes increased with increasing amorphous EVA content in semi-crystalline PEO. In particular, the blend membrane with 40 wt% EVA showed $CO_2$ permeability of 64 Barrer and $CO_2/N_2$ ideal selectivity of 61.5. The high $CO_2$ permeability and $CO_2/N_2$ ideal selectivity are attributed to strong affinity between the polar ether groups of PEO or the polar ester groups of EVA and polar $CO_2$.

• Korean Journal of Agricultural Science
• /
• v.43 no.3
• /
• pp.340-345
• /
• 2016

The kiwi fruit (Actinidia deliciosa cv. 'Hayward') should be ripened at any step during postharvest handling before consumer consumption. This is essential for freshly harvested kiwi fruit. But, this requires correct temperatures and ethylene concentrations. More testing of a newly developed ethylene generator using charcoal for commercial purposes is needed. This study was conducted to investigate the optimum storage temperatures and the effect of ethylene on the postharvest quality of kiwi fruit. Three different ethylene concentrations of 10, 50, and $100{\mu}L{\cdot}L^{-1}$ were used on fresh kiwi fruit stored at different temperatures of 10, 15, and $20^{\circ}C$. The quality changes of the fruits were assessed by sensory evaluation and by measuring firmness, soluble solids content, titratable acidity, and ethylene production. Higher storage temperatures and ethylene concentrations softened the kiwi fruit quickly and led to the rapid loss of acidity while soluble solid contents of fruit increased to a significant extent during the same storage period. Similarly, the firmness of ethylene-treated fruits stored at 20 and $15^{\circ}C$ dramatically decreased in the experiment while treated fruits stored at $10^{\circ}C$ decreased only slightly. Quality characteristics of kiwi fruits stored at 15 and $20^{\circ}C$ were better than those of fruits at $10^{\circ}C$. With regards to the effect of temperature, fruits stored at lower temperatures took a longer time to ripen and retained their quality longer. The newly developed ethylene generator maintained the ethylene concentration in the 5 kg box at $40-400{\mu}L{\cdot}L^{-1}$. The ethylene generator could also be used to soften persimmons.

• Korean Journal of Materials Research
• /
• v.1 no.3
• /
• pp.151-155
• /
• 1991

The kinetics of isothermal crystallization in blends of poly(ethylene oxide) (PEO) and poly(styrene-co-acrylic acid) (SAA) has been examined as a function of the blend ratio, the copolymer composition, and the crystallization temperature, based on the Avrami eauation. The Avrami exponents were mostly chose to 2, independent of the crystallization temperature. The crystallization rate of PEO in PEO/SAA blends decreased with the increase of SAA content. And also, the higher the acrylic acid content in the SAA copolymer, 7he slower the crystallization rate of PEO in the blends.