• Polymer(Korea)
• /
• v.31 no.2
• /
• pp.168-176
• /
• 2007

The sub-micron particles of poly ($\gamma-glutamic$ acid) (PGA) containing lysozyme have been prepared using supercritical antisolvent (SAS) precipitation process at various experimental conditions such as pressure, temperature, inner diameter of nozzle, and concentration. As overall results of the application of SAS process to this system, the smaller size powder has been produced as (i) increasing pressure, (ii) decreasing temperature, (iii) decreasing the inner diameter of nozzle, and (iv) decreasing the concentration of PGA and lysozyme. It is found by means of FT-IR analysis that during SAS process, the composition has changed from the original composition of PGA : lysozyme=50 : 50 into PGA : lysozyme=33 : 67 at final product powder. It means that PGA has higher solubility for the mixed solvent of carbon dioxide and dimethyl sulfoxide (DMSO). Due to such difference of solubility, this particle forms the core-shell structure of which the core consists mainly of lysozyme. It is also found that the residual DMSO amount of $7.8\times10^{-3}wt%$ exists inside the powder.

• Polymer(Korea)
• /
• v.37 no.6
• /
• pp.694-701
• /
• 2013

A new copolymer named T-TI24T (poly((5,5-(2-butyl-5,6-bisdecyloxy-4,7-di-thiophen-2-yl-isoindole-1,3-dione))- alt-(2,5-thiophene))) based on phthalimide derivative and thiophene is synthesized by the Stille-coupling reaction. The polymer shows relatively high number average molecular weight of 86500 g/mol with good solubility in common organic solvents such as chloroform, 1,2-dichlorobenzene, and toluene and is thermally stable up to $380^{\circ}C$. Besides, it possesses a relatively low highest occupied molecular orbital (HOMO) energy level of -5.33 eV, promising the high open circuit voltage ($V_{oc}$) for photovoltaic applications. Active layer solution of polymer T-TI24T-as a donor and (6)-1-(3-(methoxycarbonyl)- {5}-1-phenyl[5,6]-fullerene (PCBM)-as an acceptor in different weight ratios is applied to fabricate the polymer solar cell devices. The ratio of polymer/PCBM affects the solar cell efficiency and the best performance exhibits in the device with polymer/PCBM = 1:3 (w/w), which shows a power conversion efficiency (PCE) of 0.199% and a $V_{oc}$ of 0.99 V, respectively. Even though the device shows the very low PCE, the $V_{oc}$ is higher than that of well known bulk heterojunction type solar cell based on P3HT:PC61BM (c.a. 0.5 V).

• Journal of the Korean Wood Science and Technology
• /
• v.28 no.2
• /
• pp.32-41
• /
• 2000

Antimicrobial and antioxidative activities on heartwood extractives from Zelkova serrata were investigated to develop a natural fungicide or preservative. The ethanol extract from Z. serrata was fractionated in the order of petroleum ether, diethylether and ethylacetate to determine antimicrobial activity. The highest antimicrobial activity against the tested microorganisms was found in the petroleum ether soluble fraction. An active antimicrobial compound was isolated from petroleum ether soluble fraction, and identified as 7-hydroxy-3-methoxycadalene by $^1H$-, $^{13}C$-NMR and EI-MS spectrometry. This compound showed higher antifungal activity, but lower antibacterial activity than hinokitiol(${\beta}$-thujaplicin), strong antimicrobial compound isolated from Thujopsis dolabrata. Antioxidative activity was also higher than ${\alpha}$-tocopherol and similar to BHT(butylated hydroxytoluene), one of the strongest synthetic antioxidant. As a result, it was concluded that 7-hydroxy-3-methoxycadalene isolated from Z. serrata had strong antifungal and antioxidative activities.

• Korean Journal of Weed Science
• /
• v.15 no.2
• /
• pp.121-130
• /
• 1995

Greenhouse and laboratory studies were conducted to investigate allelopathic potential of some weed species on alfalfa(Medicago sativa L.) germination and seedling growth. In the comparison between top(leaves+stems) and root extracts, top extract exhibited greater allelopathic effects on alfalfa germination than that of root. The various weed species extract differently responded to alfalfa test species, WL-320, in terms of allelopathic effect. Top and root aqueous extracts of lambsquarter(Chenopodium album L.), giant foxtail(Setaria faberii Herrm.), redroot pigweed (Amaranthus retroflexus L.), velvetleaf(Abutilon theophrasti Medic.), crabgrass(Digitaria sanguinalis L.), canada thistle(Cirsium arvense L.) and prostrate knotweed(Polygonium aviculare L.) significantly inhibited germination, seedling length, weight, vigor, and rate of germination of alfalfa. The regression slopes of various top extracts showed that velvetleaf(b=3.69) extracts were the most inhibitory, while large crabgrass(b=2.39) extracts had the least allelopathic effect on alfalfa germination. Germination, seedling length and weight of alfalfa were inversely proportional to the concentration of dried velvetleaf extracts. Also, more of the toxic effects were observed from the dried extracts compared to the fresh extracts. Residue of velvetleaf inhibited significantly alfalfa emergence and survival percentage compared to the control. The emergence and survival percentage of alfalfa were 44%, 57% at 1.0% residue treatment, respectively. When weed residues were mixed with silica sand with incubation time, velvetleaf residue most inhibited alfalfa growth. The degree of inhibition increased as incubation time increased. An incubation for 72h caused the greatest inhibition of alfalfa growth. These results demonstrate the different allelopathic activity of weed species extracts on alfalfa and suggest that weed may affect alfalfa growth and development through the inhibitory effects of allelochemicals present in weed tissue.

• Weed & Turfgrass Science
• /
• v.2 no.2
• /
• pp.111-121
• /
• 2013

Literatures were reviewed to understand the weeds occurring on the lawn and the effective control methods of them. Thirty-seven species of 16 families including three species of Cyperaceae for example Cyperus sanguinolentus, nine species of Poaceae including Digitalis ciliaris, Poa repens, etc., and 25 species of broad-leaved weeds such as Artemisia princeps, Draba nemorosa, Hydrocotyle sibthorpioides were occurred on the lawns. One hundred ninety-six weed species of 53 families were occurred on a tomb graveyard adjacent to the mountain. Therefore, it is possible to be infested by the weeds occurring on the graveyard on the golf course adjacent to the mountains. There are 67 items, 32 kinds of the soil treatment herbicides including dichlobenil GR, methiozolin EC, oxaziclomefone SC, imaxaquin GR et al, and 35 kinds of the foliar treatment herbicides including metamifop EC, bifenox flucetosulfuron WG, flazasulfuron WP, trifloxysulfuron-sodium WG et al. registered at the end of May 2012 for efficient management of the weeds occurring on the lawn. For effective management of the weeds, the herbicide can be generally applied twice a year on March to April and August to September for soil treatment and once a year on June to July for the foliage treatment.

• Korean Journal of Microbiology
• /
• v.42 no.2
• /
• pp.135-141
• /
• 2006

We isolated a bacterium which produces antifungal substances from the Sanktpeterburg soils at Russia. The iso-lated strain was identified as Brevibacillus sp. and shown a strong antifungal activity on plant pathogenic fungi. Brevibacillus sp. KMU-391 produced maximum level of antifungal substances under incubation aerobically at $30^{\circ}C$ for 48 hours in trypticase soybean broth containing 1.0% sucrose and 1.0% polypeptone at 180 rpm and initiated pH adjusted to 7.0. Precipitate of culture broth by $30{\sim}60%$ ammonium sulfate precipitation exhibited strong antifungal activity against Didymella bryoniae by dry cell weight. Butanol extract of cultured broth also shown fungal growth inhibitory activity against Botrytis cinerea KACC 40573, Botrytis fabae KACC 40962, Colletotrichum gloeosporioides KACC 40804, Colletotrichum orbiculare KACC 40808, Didymella bryoniae KACC 40669, Fusarium graminearum KACC 41040, Fusarium oxysporum KACC 40037, Fusarium oxysporum KACC 40052, Fusarium oxysporum f, sp. radicis-Iycopersici KACC 40537, Fusarium oxysporum KACC 40902, Monosporascus cannonballus KACC 40940, Phytophthora camvibora KACC 40160, Rhizoctonia solani AG-1(IA) KACC 40101, Rhizoctonia solani AG-4 KACC 40142, and Scleotinia scleotiorum KACC 41065 by agar diffusion method.

• Research in Plant Disease
• /
• v.12 no.2
• /
• pp.69-74
• /
• 2006

Basal rot of freesia caused by a Sclerotium sp. occurred at Incheon areas. Incidence of the disease reached up to 45% and averaged 17.0% in the fields. Typical symptoms consisted of sheath dry and leaf blight due to rots on basal leaves. The causal fungus was identified as Sclerotium sp. based on following mycological characteristics. The fungus formed sclerotia on cultural media and plant tissues, but did not produce asexual spores. On cultural medium, aerial mycelia of the fungus changed color from white to clay with cultural age and smelled musty odor. Numerous irregular and elliptical black microsclerotia of the fungus were formed on potato dextrose agar (PDA) after 5 days of incubation at $25^{\circ}C$ and sized $115{\sim}200{\times}95{\sim}150 (av. 145{\sim}126.5){\mu}m$. The fungus grew at $10{\sim}32^{\circ}C$ and $pH 4.0{\sim}8.5$. However, the optimal temperature and pH for mycelial growth of the fungus were $24^{\circ}C$ and 5.5 respectively. The isolate showed present pathogenicity to not only freesia but gladiolus in the pathogenicity test, and the symptoms were similar to those observed in the fields. Basal rot of freesia caused by Sclerotium sp. is firstly reported in Korea.

• Applied Chemistry for Engineering
• /
• v.16 no.6
• /
• pp.800-808
• /
• 2005

The compounding resin for biodegradable wrap was developed, and its manufacturing process and physical properties were studied. For these purposes, following factors were optimized: the types and amounts of raw resin material, anti-oxidants, and lubricants used. In this work, the stable compounding resin used to make biodegradable wrap was based on poly(butylene adipate-co-butylenesuccinate) (PBAS) and poly(butyleneadipate-co-butylene succinate-co-butyleneterephthalate) (PBAST). The improved properties of resin with an additive were investigated by melting flow index (MFI). From these results, the physical properties of compounding resin, based on PBAST, were more than those of PBAS. For PBAS, the Irganox 1010, 1076 and Irgafos TNPP as the first and second anti-oxidants, respectively, were good. For PBAST, the good first and second anti-oxidants, respectively, were Irganox 1076 and Mark PEP 36. The good lubricants for feeding PBAS and PBAST were glycerol monostearate and palmityl alcohol, respectively. The stability and tensile strength experiment of wrap were also investigated by the elution of heavy metals and universal testing machine (UTM), respectively. The decomposition ratio of developed wrap was increased proportional to the reclaiming time. The degradation ratio of compounding resin sample was about 60% after 40 days.

• Applied Chemistry for Engineering
• /
• v.25 no.3
• /
• pp.254-261
• /
• 2014

The transformer is a static electrical device that transfers energy by inductive coupling. Then, heat is occurred at coils, inner transformer was filled with insulating oils for cooling and insulation. Although mineral oil as insulating oil has been widely used, it does not meet health and current environmental laws because it is not biodegradable. Therefore, in this study, the diglycerol ester was synthesized with diglycerol and fatty acids (oleic acid and caprylic acid) over various catalysts for insulating oil having biodegradability, high flash points and low pour points. The sulfated zirconia ($SO_4{^{2-}}/ZrO_2$) catalyst prepared at different calcination temperature shows the highest conversion of fatty acids at $600^{\circ}C$ due to crystallinity and high density of acid sites per surface area. When the molar ratio of oleic acid and caprylic acid is 1:3, the diglycerol ester shows superior insulation properties that are the flash point of $306^{\circ}C$ and pour point of $-50^{\circ}C$. The insulation properties of synthesized diglycerol ester shows the pour point of $-50^{\circ}C$ and the flash point of over $300^{\circ}C$. Therefore, diglycerol ester is superior to the vegetable oils in insulation properties.

• Korean Journal of Food Science and Technology
• /
• v.45 no.1
• /
• pp.8-12
• /
• 2013

Photostimulated luminescence (PSL) and thermoluminescence (TL) analyses were conducted for the detection of different irradiated dried fishes. All the non-irradiated samples provided PSL counts of lower than 700 (negative: $T_1$). Clear identification of irradiated sample was only possible for irradiated anchovy with PSL counts >5000; however, the results were unsatisfactory (not positive) for irradiated cod, dried filefish, hairtail, and herring samples. The contaminating silicate minerals were obtained by density separation or acid hydrolysis to perform TL analysis, which resulted in a low intensity of TL glow curve with a maximum peak after $250^{\circ}C$ for the non-irradiated samples that are irrespective of their kinds and methods for the mineral separation. The TL glow curves of high intensity with maximum peak in the temperature range of $150-250^{\circ}C$ were observed for all the irradiated samples. However, better results of TL glow curves and particularly of the TL ratio ($TL_1/TL_2$) were obtained when the minerals were separated by a acid hydrolysis method.