• Composites Research
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• v.30 no.1
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• pp.21-25
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• 2017

The aim of this study is to fabricate composite bone plates consisted of unidirectional biodegradable glass fibers (BGF) and polylactic acid (PLA) and evaluate the performance of the composite bone plates according to the temperature ($50.0^{\circ}C$) of PBS (Phosphate Buffer Saline) solution and exposure time (0~3 weeks). Mechanical characteristics, such as bending stiffness, flexural strength, water uptake and mass loss, were investigated and the results showed that mechanical properties of the plates decreased as soaking duration increased due to loss of composite material.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.7 no.2
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• pp.63-68
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• 1974

The growth of sea weeds is greatly affected by the environmental conditions of ambient water. Especially nutrient salts in sea water function as a major factor to the growth of lavers, so that the content of inorganic substances in lavers could he a criterion for quality evaluation of lavers. In this experiment, the relation between the quality and the content of Zinc and Magnesium which are not only physiologically active and closely related with pigments such as chlorophll and phycobilins but also important in quantify is discussed if such a measurement to be an index for quality evaluation. Sixteen samples of layers were collected from three different culture farms, 7 from Jangrim-Busan, 6 from Wando-Jeon Nam, 3 from Hadong-Gyeong Nam, and classified into 3 quality grades to each farm and to whole samples by organoleptic test. Zinc and Magnesium were analyzed by atomic absorption spectrophotometry. For pigment analysis, chlorphyll was extracted with 85 percent acetone, filtered and the absorbance was measured at 660 nm and the residue was further extracted with phosphoric buffer solution to determine the optical density for phycobilins at 560 nm. The result showed that the total content of Zinc and Magnesium varied between the farms, but kept consistent with quality grades from the same farm. The Zinc content was correlated proportion- ally with the content of phycobilins, and Magnesium content in total ash could roughly represent the content of chlorophll except some examples in which the Magnesium content of chlorophyll-ext ractresiduewasexceptionallyhigher. In conclusion the contents of these metals provide an applicable index for quality judgment of lavers.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.5
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• pp.565-569
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• 1993

Antioxidative activity of browning product(BP) fractionated from fermented soybean sauce(SS) was studied during the oxidation process of linoleic acid mixture system. SSBP was a powder type product prepared from fermented soybean sauce by the fractionation through the Sephadex G-10 column and freeze drying of collected fraction. The aqueous model systems were used for the evaluation of antioxidative activity of SSBP during the oxidative reaction at $50^{\circ}C$ by the determination of peroxider and conjugated dienoic acid compounds. The linoleic acid mixture for the aqueous model systems was consisted of linoleic acid(64.6%), oleic acid(27.4%), and other acids in ethanolic phosphate buffer solution(pH 7.0). SSBP had a considerable antioxidative activity with the inhibition of formation of peroxides and conjugated dienoic acids during the autoxidation of linoleic acid mixtures in aqueous model systems. Antioxidative activity of SSBP was relatively higher than SS, however, lower than ${\alpha}-tocopherol$ and butylated hydroxyanisol. The antioxidative effect of SSBP was increased by the its concentrations from 0.05% to 0.5% in the oxidation reactions of aqueous model systems. Therefore, SSBP was considered as one of the potential natural antioxidants for the use of food products.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.5
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• pp.570-575
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• 1993

Antioxidative characteristics of melanoidin related products(MRPs) fractionated from fermented soybean sauce were studied during the oxidation process of model systems. MRPs were prepared from soybean sauce fermented for 6 months after inoculation Aspergillus oryzae by the fractionation through the Sephadex G-10 column and the freeze drying of collected fractions. MRPs inhibited the formation of peroxides during the oxidation of linoleic acids mixture in ethanolic phosphate buffer solution at $50^{\circ}C$ with the increasing tendency by their concentration in reaction systems. MRPs had hydrogen doner properties during the reaction with ${\alpha},\;{\alpha}'-diphenyl-{\beta}-picrylhydrazyl$ and also MRPs inhibited the iron and lipoxygenase catalytic oxidation. MRPs were found to be fairly stable with no loss of antioxidative effect after storage at $50^{\circ}C$ for 15days.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.1
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• pp.54-62
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• 2018

Objective: Due to the threat of global warming, the livestock industry is increasingly interested in exploring how feed additives may reduce anthropogenic greenhouse gas emissions, especially from ruminants. This study investigated the effect of Rhodophyta supplemented bovine diets on in vitro rumen fermentation and rumen microbial diversity. Methods: Cannulated Holstein cows were used as rumen fluid donors. Rumen fluid:buffer (1:2; 15 mL) solution was incubated for up to 72 h in six treatments: a control (timothy hay only), along with substrates containing 5% extracts from five Rhodophyta species (Grateloupia lanceolata [Okamura] Kawaguchi, Hypnea japonica Tanaka, Pterocladia capillacea [Gmelin] Bornet, Chondria crassicaulis Harvey, or Gelidium amansii [Lam.] Lamouroux). Results: Compared with control, Rhodophyta extracts increased cumulative gas production after 24 and 72 h (p = 0.0297 and p = 0.0047). The extracts reduced methane emission at 12 and 24 h (p<0.05). In particular, real-time polymerase chain reaction analysis indicated that at 24 h, ciliate-associated methanogens, Ruminococcus albus and Ruminococcus flavefaciens decreased at 24 h (p = 0.0002, p<0.0001, and p<0.0001), while Fibrobacter succinogenes (F. succinogenes) increased (p = 0.0004). Additionally, Rhodophyta extracts improved acetate concentration at 12 and 24 h (p = 0.0766 and p = 0.0132), as well as acetate/propionate (A/P) ratio at 6 and 12 h (p = 0.0106 and p = 0.0278). Conclusion: Rhodophyta extracts are a viable additive that can improve ruminant growth performance (higher total gas production, lower A/P ratio) and methane abatement (less ciliateassociated methanogens, Ruminococcus albus and Ruminococcus flavefaciens and more F. succinogenes.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.139-139
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• 2010

Ionic Transition Metal Complex based (iTMC) Light-emitting electrochemical cells (LEECs) have been drawn attention for cheap and easy-to-fabricate light-emitting device. LEEC is one of the promising candidate for next generation display and solid-state lighting applications which can cover the defects of current commercial OLEDs like complicated fabrication process and strong work-function dependent sturucture. We have investigated the performance characteristics of LEECs based on poly (3, 4-ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS)-incorporated transition metal complex, which is tris(2, 2'-bipyridyl)ruthenium(II) hexafluorophosphate in this study. There are advantages using conductive polymer-incorporated luminous layer to prevent light disturbance and absorbance while light-emitting process between light-emitting layer and transparent electrode like ITO. The devices were fabricated as sandwiched structure and light-emitting layer was deposited approximately 40nm thickness by spin coating and aluminum electrode was deposited using thermal evaporation process under the vacuum condition (10-3Pa). Current density and light intensity were measured using optical spectrometer, and surface morphology changes of the luminous layer were observed using XRD and AFM varying contents of PEDOT:PSS in the Ruthenium(II) complex solution. To observe enhanced ionic conductivity of PEDOT:PSS and luminous layer, space-charge-limited-currents model was introduced and it showed that the performances and stability of LEECs were improved. Main discussions are the followings. First, relationship between film thickness and performance characteristics of device was considered. Secondly, light-emitting behavior when PEDOT:PSS layer on the ITO, as a buffer, was introduced to iTMC LEECs. Finally, electrical properties including carrier mobility, current density-voltage, light intensity-voltage, response time and turn-on voltages were investigated.

• Journal of Microbiology and Biotechnology
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• v.23 no.6
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• pp.864-871
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• 2013

The recombinant strain P. pastoris GS115-lccC was used to produce laccase with high activity. Factors influencing laccase expression, such as pH, methanol concentration, copper concentration, peptone concentration, shaker rotate speed, and medium volume were investigated. Under the optimal conditions, laccase activity reached 12,344 U/L on day 15. The recombinant enzyme was purified by precipitating and dialyzing to electrophoretic homogeneity, and was estimated to have a molecular mass of about 58 kDa. When guaiacol was the substrate, the laccase showed the highest activity at pH 5.0 and was stable when the pH was 4.5~6.0. The optimal temperature for the laccase to oxidize guaiacol was $60^{\circ}C$, but it was not stable at high temperature. The enzyme could remain stable at $30^{\circ}C$ for 5 days. The recombinant laccase was used to degrade chlorpyrifos in several laccase/mediator systems. Among three synthetic mediators (ABTS, HBT, VA) and three natural mediators (vanillin, 2,6-DMP, and guaiacol), vanillin showed the most enhancement on degradation of chlorpyrifos. Both laccase and vanillin were responsible for the degradation of chlorpyrifos. A higher dosage of vanillin may promote a higher level of degradation of chlorpyrifos, and the 2-step addition of vanillin led to 98% chlorpyrifos degradation. The degradation of chlorpyrifos was faster in the L/V system ($k_{obs}$ = 0.151) than that in the buffer solution ($k_{obs}$ = 0.028).

• Microbiology and Biotechnology Letters
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• v.9 no.3
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• pp.165-171
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• 1981

The penicillin amidase from Escherichia coli (ATCC 9637) was immobilized by entrappment in gelatin and DEAE-cellulose mixture cross-linked with glutaraldehyde, and the kinetics in a differential column reactor was studied. The optimal operating condition of a differential reactor was reasonably met when the enzyme loading was 1g, and 30 mM substrate solution in 0.1 M phosphate buffer (pH 8.0) was fed at flow rate 4$m\ell$/min and 4$0^{\circ}C$. The optimal pH and temperature were found to be 8.0 and 55$^{\circ}C$, respectively. The Michaelis-Menten constant was 4.8 mM while the maximum velocity was 308 units/g of the immobilized enzyme under the condition of the differential reactor. The effect of substrate inhibition disappeared in the immobilized enzyme preparation. The differential reactor was proved to be good for studying the true kinetics since the pH drop and the external diffusional resistance could be eliminated.

• Applied Chemistry for Engineering
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• v.1 no.2
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• pp.182-189
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• 1990

Various crosslinked poly(4-vinylpyridines) having different degrees of crosslinking were prepared by radical copolymerizations of 4-vinylpyridine with N, N'-2, 6-pyridinebisacrylamide as a crosslinker. The abilities of these crosslinked polymers to bind methyl orange and butyl orange were investigated at various temperatures in a buffer solution of pH 7. The first binding constants were evaluated from the equilibrium binding amounts. The first binding constants against the temperatures showed bell-shaped curves. Also, the first binding constants against the degree of crosslinking showed bell-shaped curves. When the temperature and the degree of crosslinking of maximum binding in the curves of these binding systems were compared with those of previous systems containing crosslinked poly(4-vinylpyridines) prepared by using N, N'-methylenebisacrylamide, N, N'-tetramethy-lenebisacryamide and divinylbenzene as crosslinkers, respectively, they were varied with the crosslinked poly(4-vinyl pyridines) containing different crosslinkers. These results were discussed in terms of the properties of the crosslinkers.

• Korean Journal of Food Science and Technology
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• v.19 no.2
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• pp.146-150
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• 1987

The effects of pH and added salts on the partition coefficients of proteins in a polyethylene glycol)-dextran aqueous two-phase system were investigated. The partition coefficients attained the lowest value at the isoelectric point of proteins in an equal volume aqueous two-phase system containing 5% PEG and 9.5% dextran in 5 mM phosphate buffer solution. The coefficients increased dramatically at pH 11; BSA which had highest effective hydrophobicity marked 50-fold increase, while ${\beta}-lactoglobulin$ and ovalbumin which had low hydrophobicity 10-fold increase, respectively. The effect of added salts varied with the pH. The partition coefficient increased by the addition of salt at pH 3.0 but decreased drastically at pH 7.0. The partition coefficient increased in the order of added Li < Na < K at pH 3.0 and decreased in the order of added Li < Na < K at pH 11.0.