• Title/Summary/Keyword: co-substrate

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Enzymatic Characteristics of Polyphenol Oxidase from Apple (Ralls Janet) (사과(Ralls Janet) Polyphenol Oxidase의 효소학적(酵素學的) 성질(性質))

  • Chung, Ki Taek;Seu, Seung Kyo;Song, Hyung Ik
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.12 no.4
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    • pp.316-322
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    • 1983
  • In order to obtain elementary data of enzymatic browning of apples and apple products and to examine effectively inhibitory method of browning, we extracted polyphenol oxidase (EC 1.10.3.1) from apple (Ralls Janet) and investigated its general properties. The optimum conditions for the enzyme reaction were pH 6.0 and temperature of $30^{\circ}C$. The enzyme was very stable at pH 4.0, and at the range of pH 5.0-9.0 its activity was above 80% compared with pH 4.0. The enzyme was very stable by heating at $40^{\circ}C$ for 1 hour, and almost 50% of enzyme activity was lost by heating at $60^{\circ}C$ for 30 minutes. The polyphenol oxidase activity was enhanced by the addition of $Cu^{2+}$ and $Mn^{2+}$, respectively, meanwhile $Na^+$, $Hg^{2+}$ and $Co^{2+}$ inhibited the enzyme activity. The enzyme activity was greatly decreased in the presence of inhibitors such as cysteine, sodium metabisulfite and ascorbic acid. The polyphenol oxidase greatly catalyzed the oxidation of o-diphenols such as chlorogenic acid and catechol, which suggests that main substrate of polyphenol oxidase is o-diphenol compounds.

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Evaluations of Si based ternary anode materials by using RF/DC magnetron sputtering for lithium ion batteries

  • Hwang, Chang-Muk;Park, Jong-Wan
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.08a
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    • pp.302-303
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    • 2010
  • Generally, the high energy lithium ion batteries depend intimately on the high capacity of electrode materials. For anode materials, the capacity of commercial graphite is unlike to increase much further due to its lower theoretical capacity of 372 mAhg-1. To improve upon graphite-based negative electrode materials for Li-ion rechargeable batteries, alternative anode materials with higher capacity are needed. Therefore, some metal anodes with high theoretic capacity, such as Si, Sn, Ge, Al, and Sb have been studied extensively. This work focuses on ternary Si-M1-M2 composite system, where M1 is Ge that alloys with Li, which has good cyclability and high specific capacity and M2 is Mo that does not alloy with Li. The Si shows the highest gravimetric capacity (up to 4000mAhg-1 for Li21Si5). Although Si is the most promising of the next generation anodes, it undergoes a large volume change during lithium insertion and extraction. It results in pulverization of the Si and loss of electrical contact between the Si and the current collector during the lithiation and delithiation. Thus, its capacity fades rapidly during cycling. Si thin film is more resistant to fracture than bulk Si because the film is firmly attached to the substrate. Thus, Si film could achieve good cycleability as well as high capacity. To improve the cycle performance of Si, Suzuki et al. prepared two components active (Si)-active(Sn, like Ge) elements film by vacuum deposition, where Sn particles dispersed homogeneously in the Si matrix. This film showed excellent rate capability than pure Si thin film. In this work, second element, Ge shows also high capacity (about 2500mAhg-1 for Li21Ge5) and has good cyclability although it undergoes a large volume change likewise Si. But only Ge does not use the anode due to its costs. Therefore, the electrode should be consisted of moderately Ge contents. Third element, Mo is an element that does not alloys with Li such as Co, Cr, Fe, Mn, Ni, V, Zr. In our previous research work, we have fabricated Si-Mo (active-inactive elements) composite negative electrodes by using RF/DC magnetron sputtering method. The electrodes showed excellent cycle characteristics. The Mo-silicide (inert matrix) dispersed homogeneously in the Si matrix and prevents the active material from aggregating. However, the thicker film than $3\;{\mu}m$ with high Mo contents showed poor cycling performance, which was attributed to the internal stress related to thickness. In order to deal with the large volume expansion of Si anode, great efforts were paid on material design. One of the effective ways is to find suitably three-elements (Si-Ge-Mo) contents. In this study, the Si based composites of 45~65 Si at.% and 23~43 Ge at.%, and 12~32 Mo at.% are evaluated the electrochemical characteristics and cycle performances as an anode. Results from six different compositions of Si-Ge-Mo are presented compared to only the Si and Ge negative electrodes.

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Syntheses of 70% Solids Acrylic Resin and Comparative Study in Physical Properties as Acrylic Urethane Resin Coatings (고형분 70% 아크릴수지 합성과 아크릴-우레탄 도료의 도막물성 비교 연구)

  • Kim, Seong-Kil;Park, Hyong-Jin
    • Journal of the Korean Applied Science and Technology
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    • v.38 no.2
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    • pp.476-487
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    • 2021
  • To prepare acrylic resin coatings containing 70% of solids, we used n-butyl methacrylate(BMA), methyl methacrylate(MMA), 2-hydroxyethyl methacrylate(2-HEMA), and acetoacetoxyethyl acrylate(AAEA), caprolactone acrylate(CLA) as raw materials, the glass transition temperature(Tg) of acrylic copolymer was adjusted around 50 ℃. The viscosity and molecular weight of the acrylic resins was increased with increasing OH values. Di-tert-amyl peroxide was found to be the suitable initiator to get high-solids acrylic resins. The optimum reaction conditions found in the study are 5 wt% of initiator, 4 wt% of chain transfer agent, 4 hrs of dropping time, and 140 ℃ of reaction temperature. The structure of the synthesized resins were characterized by FT-IR and 1H-NMR spectroscopy. Number average molecular weight of 1900~2600 and molecular wight distribution of 1.4~2.1 were obtained. Crosslinked acrylic urethane clear coatings were obtained by curing reaction between the synthesized acrylic resins and hexamethylene diisocyanate trimer(Desmodur N-3300), the equivalent ratio of NCO/OH was 1.2/1.0. The physical properties from the following studies were carried out: viscosity(Zahn cup #2), adhesion, drying time, pot-life, pensil hardness, and 60° specular gloss. Various properties of the acrylic urethane clear coatings were also evaluated on the coating specimens. Adhesion property to a substrate, drying time, pot-life, pencil hardness, and 60° specular gloss of prepared paint showed quite good properties. Futhermore, prepared paint containing 10% of CLA showed quite good properties for adhesion, low viscosity and high hardness.

Development of Compact and Lightweight Broadband Power Amplifier with HMIC Technology (HMIC 기술을 적용한 소형화 경량화 광대역 전력증폭기 개발)

  • Byun, Kisik;Choi, Jin-Young;Park, Jae Woo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.11
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    • pp.695-700
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    • 2018
  • This paper presents the development of compact and lightweight broadband power amplifier module using HMIC (Hybrid Microwave Integrated Circuit) technology that could be high-density integration for many non-packaged microwave components into the small area of a high dielectric constant printed circuit board, such as a ceramic substrate, also using the special design and fabrication schemes for the structure of minimized electromagnetic interference to obtain the homogeneous electrical performance at the wideband frequency. The results confirmed that the small signal gain has a gain flatness of ${\pm}1.5dB$ within the range of 32 to 36 dB. In addition, the output power satisfied more than 30 dBm. The noise figure was measured within 7 dB, and OIP3 (Output Third Order Intercept Point) was more than 39 dBm. The fabricated broadband power amplifier satisfied the target specification required to electrically drive the high power amplifiers of jamming generators for electronic warfare, so the actual applicability to the system was verified. Future studies will be aimed at designing other similar microwave power amplifiers in the future.

Exocyclic GpC DNA methyltransferase from Celeribacter marinus IMCC12053 (Celeribacter marinus IMCC12053의 외향고리 GpC DNA 메틸트랜스퍼라아제)

  • Kim, Junghee;Oh, Hyun-Myung
    • Korean Journal of Microbiology
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    • v.55 no.2
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    • pp.103-111
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    • 2019
  • DNA methylation is involved in diverse processes in bacteria, including maintenance of genome integrity and regulation of gene expression. CcrM, the DNA methyltransferase conserved in Alphaproteobacterial species, carries out $N^6$-adenine or $N^4$-cytosine methyltransferase activities using S-adenosyl methionine as a co-substrate. Celeribacter marinus IMCC12053 from the Alphaproteobacterial group was isolated from a marine environment. Single molecule real-time sequencing method (SMRT) was used to detect the methylation patterns of C. marinus IMCC12053. Gibbs motif sampler program was used to observe the conversion of adenosine of 5'-GANTC-3' to $N^6$-methyladenosine and conversion of $N^4$-cytosine of 5'-GpC-3' to $N^4$-methylcytosine. Exocyclic DNA methyltransferase from the genome of strain IMCC12053 was chosen using phylogenetic analysis and $N^4$-cytosine methyltransferase was cloned. IPTG inducer was used to confirm the methylation activity of DNA methylase, and cloned into a pQE30 vector using dam-/dcm- E. coli as the expression host. The genomic DNA and the plasmid carrying methylase-encoding sequences were extracted and cleaved with restriction enzymes that were sensitive to methylation, to confirm the methylation activity. These methylases protected the restriction enzyme site once IPTG-induced methylases methylated the chromosome and plasmid, harboring the DNA methylase. In this study, cloned exocyclic DNA methylases were investigated for potential use as a novel type of GpC methylase for molecular biology and epigenetics.

Fucoidan Stimulates Glucose Uptake via the PI3K/AMPK Pathway and Increases Insulin Sensitivity in 3T3-L1 Adipocytes (후코이단의 3T3-L1 지방세포에서 PI3K/AMPK 경로를 통한 포도당 흡수 촉진 및 인슐린 민감성 증진 효과)

  • Lee, Ji Hee;Park, Jae Eun;Han, Ji Sook
    • Journal of Life Science
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    • v.31 no.1
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    • pp.1-9
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    • 2021
  • Brown seaweeds have been shown to decrease blood glucose levels and improve insulin sensitivity previously. In this study, we investigated the effect of fucoidan, a complex polysaccharide derived from brown seaweeds, on glucose uptake to improve insulin resistance, and examined its mechanism of action in 3T3-L1 adipocytes. We observed that fucoidan significantly increased glucose uptake and it was related to an increased expression of plasma membrane-glucose transporter 4 (PM-GLUT4) in 3T3-L1 adipocytes. Fucoidan treatment increased the activation of phosphatidylinositol-3-kinase (PI3K) and the phosphorylation of insulin receptor substrate 1 (IRS1tyr) compared with that of the control cells. Fucoidan also promoted the phosphorylation of Akt and protein kinase C (PKC)-λ/ζ compared to that of the control cells. Moreover, fucoidan significantly upregulated acetyl-CoA-carboxylase (ACC) and adenosine monophosphate - activated protein kinase (AMPK) phosphorylation. As a result, translocation of GLUT4 was significantly enhanced in 3T3-L1 adipocytes, which significantly promoted glucose uptake via the PI3K/AMPK pathways. The elevation of glucose uptake by fucoidan was blocked by inhibitor of PI3K and inhibitor of AMPK in 3T3-L1 adipocytes. These findings indicate that fucoidan might ameliorate glucose uptake through GLUT4 translocation to the plasma membrane by activating the PI3K/Akt and AMPK pathways in 3T3-L1 adipocytes. Fucoidan is thought to be of high material value to diabetes treatments and functional foods.

Effect of amaranth seed extracts on glycemic control in HepG2 cells (HepG2 세포에서 아마란스 종자 에탄올 추출물이 포도당 흡수 조절에 미치는 효과)

  • Park, So Jin;Park, Jong Kun;Hwang, Eunhee
    • Journal of Nutrition and Health
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    • v.54 no.6
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    • pp.603-617
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    • 2021
  • Purpose: This study was carried out to investigate the effect of amaranth seed extracts on glycemic regulation in HepG2 cells. The 80% ethanol extracts of amaranth seeds were used to evaluate α-amylase and α-glucosidase activities, cell viability, glucose uptake and messenger RNA (mRNA) expression levels of acetyl-CoA carboxylase (ACC), glucose transporter (GLUT)-2, GLUT-4, insulin receptor substrate (IRS)-1 and IRS-2. Methods: The samples were prepared and divided into 4 groups, including germinated black amaranth (GBA), black amaranth (BA), germinated yellow amaranth (GYA) and yellow amaranth (YA). Glucose hydrolytic enzyme, α-amylase and α-glucosidase activities were examined using a proper protocol. In addition, cell viability was measured by MTT assay. Glucose uptake in cells was measured using an assay kit. The mRNA expression levels of ACC, GLUT-2, GLUT-4, IRS-1 and IRS-2 were measured by reverse transcription polymerase chain reaction. Results: The inhibitory activities of α-amylase and α-glucosidase were highly observed in GBA, followed by BA, GYA and YA. Similar results were observed for glucose. The GBA effect was similar compared to the positive control group. The mRNA expression levels of ACC, GLUT-2, GLUT-4, IRS-1, and IRS-2 were significantly increased. The potential hypoglycemic effects of amaranth seed extracts were observed due to the increase in glucose metabolic enzyme activity, and glucose uptake was mediated through the upregulation of ACC, GLUT-2, GLUT-4, IRS-1, and IRS-2 expression levels. Conclusion: Our findings suggest that the amaranth seed is a potential candidate to prevent a diabetes. The present study demonstrated the possibility of using amaranth seeds, especially GBA and BA for glycemic control.

Solid-state synthesis of yttrium oxyfluoride powders and their application to plasma spray coating (옥시불화이트륨 분말의 고상합성 및 플라즈마 스프레이 코팅 적용)

  • Lee, Jung-Il;Kim, Young-Ju;Chae, Hui Ra;Kim, Yun Jeong;Park, Seong Ju;Sin, Gyoung Seon;Ha, Tae Bin;Kim, Ji Hyeon;Jeong, Gu Hun;Ryu, Jeong Ho
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.31 no.6
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    • pp.276-281
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    • 2021
  • In order to manufacture a semiconductor circuit, etching, cleaning, and deposition processes are repeated. During these processes, the inside of the processing chamber is exposed to corrosive plasma. Therefore, the coating of the inner wall of the semiconductor equipment with a plasma-resistant material has been attempted to minimize the etching of the coating and particle contaminant generation. In this study, we synthesized yttrium oxyfluoride (YOF) powder by a solid-state reaction using Y2O3 and YF3 as raw materials. Mixing ratio of the Y2O3 and YF3 was varied from 1.0:1.0 to 1.0:1.6. Effects of the mixing ratio on crystal structure and microstructure of the synthesized YOF powder were investigated using XRD and FE-SEM. The synthesized YOF powder was successfully applied to plasma spray coating process on Al substrate.

Betulinic Acid Stimulates Glucose Uptake through the Activation of PI3K and AMPK in 3T3-L1 Adipocytes (Betulinic acid의 PI3K와 AMPK경로 활성화를 통한 3T3-L1 지방세포에서 포도당 흡수 촉진 효과)

  • Lee, Jung Kyung;Park, Jae Eun;Han, Ji Sook
    • Journal of Life Science
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    • v.32 no.10
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    • pp.762-770
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    • 2022
  • Hyperglycemia in type 2 diabetes can be alleviated by promoting cellular glucose uptake. Betulinic acid (3β,-3-hydroxy-lup-20(29)-en-28-oic acid) is a pentacyclic lupane-type triterpenoid compound. Although there have been studies on the antidiabetic activity of betulinic acid, studies on cellular glucose uptake are lacking. We investigated the effects of betulinic acid on glucose uptake and its mechanism of action in 3T3-L1 adipocytes. Betulinic acid significantly stimulated glucose uptake in 3T3-L1 adipocytes by increasing the phosphorylation of the insulin receptor substrate 1-tyrosine (IRS-1tyr) in the insulin signaling pathway, which in turn stimulated the activation of phosphoinositide 3-kinase (PI3K) and the phosphorylation of protein kinase B (Akt). The activation of PI3K and Akt by betulinic acid translocated glucose transporter 4 to the plasma membrane (PM-GLUT4), thereby increasing the expression of PM-GLUT4 and thus stimulating cellular glucose uptake. Betulinic acid also significantly increased the phosphorylation/activation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase. The activation of PI3K and AMPK by betulinic acid was confirmed using the PI3K inhibitor wortmannin and the AMPK inhibitor compound C. The increase in glucose uptake induced by betulinic acid was significantly decreased by wortmannin and compound C in the 3T3-L1 adipocytes. These results suggest that betulinic acid stimulates glucose uptake by activating PI3K and AMPK in 3T3-L1 adipocytes.

Development of a Silicon Carbide Large-aperture Optical Telescope for a Satellite (SiC를 이용한 대구경 위성용 망원경 제작)

  • Bae, Jong In;Lee, Haeng Bok;Kim, Jeong Won;Lee, Kyung Mook;Kim, Myung-Whun
    • Korean Journal of Optics and Photonics
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    • v.33 no.2
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    • pp.74-83
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    • 2022
  • The entire process, from the raw material to the final system qualification test, has been developed to fabricate a large-diameter, lightweight reflective-telescope system for a satellite observation. The telescope with 3 anastigmatic mirrors has an aperture of 700 mm and a total mass of 66 kg. We baked a silicon carbide substrate body from a carbon preform using a reaction sintering method, and tested the structural and chemical properties, surface conditions, and crystal structure of the body. We developed the polishing and coating methods considering the mechanical and chemical properties of the silicon carbide (SiC) body, and we utilized a chemical-vapor-deposition method to deposit a dense SiC thin film more than 170 ㎛ thick on the mirror's surface, to preserve a highly reflective surface with excellent optical performance. After we made the SiC mirrors, we measured the wave-front error for various optical fields by assembling and aligning three mirrors and support structures. We conducted major space-environment tests for the components and final assembly by temperature-cycling tests and vibration-shock tests, in accordance with the qualifications for the space and launch environment. We confirmed that the final telescope achieves all of the target performance criteria.