• Journal of Sensor Science and Technology
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• v.25 no.6
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• pp.435-439
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• 2016

We report a novel detection technology for glycated hemoglobin (HbA1c) that is measured primarily to identify the three-month average plasma glucose concentration. In enzymatic measuring of glycated hemoglobin, the generated hydrogen peroxide was then used as a reducing agent of gold (III) for the synthesis of gold (0). Gold nanoparticles obtained from this novel approach were measured by optical and piezoelectric methods. In optical method, we have developed polymer based film-type sensor cartridge filled with all the reagents for glycated hemoglobin analysis and the cartridge worked very well having the detection limit of 0.53% of glycated hemoglobin. On the other hand, quartz crystal microbalance (QCM) sensors also have been developed to determine the abilities of surface modified QCM sensors at various levels of the concentration of glycated hemoglobin to bind gold nanoparticles and limit of detection was 0.90%. Finally, despite of relatively lower sensitivities of QCM sensor and film-type optical sensor than well-plate based optical detection, these two sensors were available to measure the glycated hemoglobin level for diabetes patients and normal person.

• Journal of Microbiology and Biotechnology
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• v.31 no.3
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• pp.429-438
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• 2021

Bacterial cellulose (BC) is widely used in the food industry for products such as nata de coco. The mechanical properties of BC hydrogels, including stiffness and viscoelasticity, are determined by the hydrated fibril network. Generally, Komagataeibacter bacteria produce gluconic acids in a glucose medium, which may affect the pH, structure and mechanical properties of BC. In this work, the effect of pH buffer on the yields of Komagataeibacter hansenii strain ATCC 53582 was studied. The bacterium in a phosphate and phthalate buffer with low ionic strength produced a good BC yield (5.16 and 4.63 g/l respectively), but there was a substantial reduction in pH due to the accumulation of gluconic acid. However, the addition of gluconic acid enhanced the polymer density and mechanical properties of BC hydrogels. The effect was similar to that of the bacteria using glycerol in another carbon metabolism circuit, which provided good pH stability and a higher conversion rate of carbon. This study may broaden the understanding of how carbon sources affect BC biosynthesis.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.1
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• pp.31-36
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• 2013

Acetylated Cellulose Ether (ACE), cellulose-based amphiphilic polymer with hydrophilic and hydrophobic, was synthesized and investigated in terms of its solubility and wettability for organic solvents and water. Acetyl group was substituted to the cellulose ether in a hydrophilic polymer by esterification. As a result of FT-IR, the peak corresponding to the hydroxyl group decreased and carboxyl acid peak increased with increasing reaction time and temperature, which signified the increase in the degree of acetylation of the ACE. There were similar thermal decomposition behaviors before and after esterification reaction until $800^{\circ}C$ so that the reaction occurred without significant structural changes of cellulose backbones. The solubility parameter of the ACE had a range of 18.5~26.4, and its viscosity and turbidity were controlled according to the solubility parameter of organic solvents. The ACE showed the hydrophilicity because the contact angle of the ACE was higher than the cellulose ether. These results confirmed that the ACE had the hydrophobicity and hydrophilicity due to the ether which was glucosidic bonding between the glucose units and un-reacted hydroxyl functional groups in the ACE.

• Polymer(Korea)
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• v.38 no.1
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• pp.31-37
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• 2014

To prepare biomass based nylon 6,5 copolymers, ${\varepsilon}$-caprolactam and 2-piperidone, the monomers of nylon 6,5 copolymers, were synthesized respectively from lysine and 5-aminovaleric acid which were produced from glucose by the fermentation process. The copolymers were then polymerized by the anionic ring opening polymerization of them at $40^{\circ}C$, using potassium tert-butoxide as a catalyst and acetyl-2-caprolactam and carbon dioxide as initiators. The prepared copolymers were characterized with various analytical methods: their viscosity molecular weight ($M_{\eta}$) was as high as 30000 g/mol and polymerization yield was over 50%, and it was found that they were semi-crystalline polymers having melting point at $165^{\circ}C$ which was much lower than its thermal degradation point, $250^{\circ}C$. These polymers were expected to have good thermal processability and application fields.

• Korean Journal of Food Science and Technology
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• v.29 no.4
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• pp.648-656
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• 1997

Thermal treatment of soymilk residue was carried out at 140, 150, and $160^{\circ}C$ for possible use as a raw material for dietary fiber, and some physicochemical properties of the extracts were investigated. Soluble dietary fiber(SDF) content of the extracts prepared under optimal conditions was more than 30% suggesting the conversion of insoluble dietary fiber to SDF. The main sugar components of the extracts were glucose, galactose, and arabinose. Analysis of the moelcular weight distribution by high performance size exclusion chromatography revealed that the proportion of high molecular weight fraction decreased and that of middle-sized polymer increased as the extraction temperature increased. The viscosity of aqueous solution of the extracts decreased with an increase in extraction temperature, but showed no trend as pH changed. The solubility increased with extraction temperature showing the highest at $160^{\circ}C$. The extract at $140^{\circ}C$ had the biggest calcium-binding capacity, which correlated with the changes in viscosity.

• Membrane Journal
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• v.24 no.2
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• pp.113-122
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• 2014

Porous poly(L-lactic acid)(PLLA) scaffold membranes were prepared via. phase separation process. Chloroform, dichloromethane and 1,4-dioxane were used as solvent and, ethyl alcohol was used as non-solvent. Morphologies, mechanical properties and mass transfer characteristics of the scaffold membranes were investigated through SEM, stress-strain test and glucose diffusion test. The scaffold membranes obtained from the casting solutions with chloroform and with dichloromethane showed similar morphologies. They showed sponge-like porous structure with the pore size in the range of $3-10{\mu}m$ and, their porosities were in 50-80% range. Using 1,4-dioxane as solvent, nano-fibrous scaffold membranes with porosities over 80% were fabricated. When the polymer content in the solution with 1,4-dioxane was lowered to 4%, highly porous, macroporous and nano-fibrous scaffold membranes were obtained. The size of the macropore was tens of the microns and the porosity was around 90%. These results indicate that the solvent has significant effect on the scaffold membrane structure and, that scaffold membranes with various structures can be fabricated through phase separation method by choosing solvent and by controlling polymer concentration in the casting solution.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.5
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• pp.524-528
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• 2002

Green layer, Enteromorpha prolifera, is regarded as one of important materials for food processing in Korea. The acidic water-soluble polysaccharide (CPC-PS) isolated from the alga with hot water and cetylpyridium chloride was mainly constituted of rhamnose, xylose, uronic acid and sulfate. To determine the glycosyl-linkages and positions of sulfate by methylation, the CPC-PS was reduced and/or sulfates. A marked increase of glucose content in the reduced polysaccharide indicated that glucuronic acid was a major sugar in the polymer and sulfation was deduced to occur on O-3 of rhamnose and O-2 of xylose. According to the methylation analysis of the native, reduced, desulfated and reduced-desulfated polymers, CPC-PS mainly composed of 1,4- and 1,2,3-linked rhamnose 3-sulfate, 1,4-linked xylose 2-sulfate, 1,4-linked xylose and 1,4-linked glucuronic acid. Minor 1,4-linked rhamnose and 1,4,6-linked galactose residues were also detected.

• Transactions of the Korean hydrogen and new energy society
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• v.19 no.5
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• pp.410-416
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• 2008

합성 및 두부 제조 폐수로부터 혐기 세균 복합체를 이용하여 수소를 생산하였다. 수소생산 혐기 세균 복합체는 하수처리장 농축 소화조에서 발생하는 슬러지를 $90^{\circ}C$에서 20분간 열처리하여 얻었다. 혐기 세균 복합체는 $37^{\circ}C$ 회분식 운전조건에서 1% (w/v) 포도당 함유 PYG (peptone-yeast extract-glucose) 배지로부터 1.15 L-$H_2$/g-균체건조량의 수소를 생산할 수 있었고, 이때 주요 유기산으로 15 mM acetate와 32 mM butyrate가 생성되었다. 같은 발효조건에서 1.4% 전분과 0.07% 환원당을 포함하는 두부 제조 폐수로부터 1.76 L $H_2$/L-두부제조폐수의 수소를 발생하였다. 이와 같은 결과로 부터 포도당과 두부 제조 폐수로부터 혐기세균 복합체에 의한 수소생산 효율은 각각 1.9과 0.9 mol $H_2$/mol 포도당을 나타내었다. 반연속운전(HRT, 12 시간)시 합성폐수를 이용하여 60일 이상 안정적으로 수소를 생산할 수 있었고, 이 때 혐기 세균 복합체는 1.3-2.0 L $H_2$/L-배양액을 발생하였다. PCR-DGGE(polymer chain reaction-denaturing gradient gel electrophoresis) 분석결과, 반응기 내 세균 복합체의 주요 미생물은 Clostridium 종이었다. 본 연구는 적절한 열처리를 통해 혐기 소화조 슬러지로부터 고활성 수소생산 세균 복합체를 얻을 수 있으며, 이들 세균 복합체를 이용하여 합성 및 두부제조 폐수로부터 효율적인 수소생산이 가능하다는 것을 나타내고 있다.

• Journal of Microbiology and Biotechnology
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• v.29 no.5
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• pp.776-784
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• 2019

Polyhydroxybutyrate (PHB), the most well-known polyhydroxyalkanoate, is a bio-based, biodegradable polymer that has the potential to replace petroleum-based plastics. Lignocellulose hydrolysate, a non-edible resource, is a promising substrate for the sustainable, fermentative production of PHB. However, its application is limited by the generation of inhibitors during the pretreatment processes. In this study, we investigated the feasibility of PHB production in E. coli in the presence of inhibitors found in lignocellulose hydrolysates. Our results show that the introduction of PHB synthetic genes (bktB, phaB, and phaC from Ralstonia eutropha H16) improved cell growth in the presence of the inhibitors such as furfural, 4-hydroxybenzaldehyde, and vanillin, suggesting that PHB synthetic genes confer resistance to these inhibitors. In addition, increased PHB production was observed in the presence of furfural as opposed to the absence of furfural, suggesting that this compound could be used to stimulate PHB production. Our findings indicate that PHB production using lignocellulose hydrolysates in recombinant E. coli could be an innovative strategy for cost-effective PHB production, and PHB could be a good target product from lignocellulose hydrolysates, especially glucose.

• Korean Journal of Food Science and Technology
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• v.29 no.1
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• pp.138-144
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• 1997

A new biopolymer YU-122 from Metarrhizium anisopliae (Metschn.) Sorok consisting of glucose and galactose was tested for its physical properties and flow behavior characteristics. Xanthan gum showed slightly higher viscosity than biopolymer YU-122. Viscosity of biopolymer YU-122 at various pHs and temperatures was also tested. The viscosity of biopolymer YU-122 was very stable up to pH 11 and $60^{\circ}C$, indicating that it has a great possibility for the application such as food additives, emulsifier, and drug release agents. Flow behavior index (n) from Power Law equation is 0.173. Biopolymer YU-122 solution was a pseudoplastic non-Newtonian fluid, which indicated that it had one or more side chains. When biopolymer YU-122 was used as a emulsifier, it stabilized the emulsion up to 120 hours, which was much better than xanthan gum. The biopolymer YU-122 could form an excellent but less clear film compared with xanthan and pullulan.