• Journal of Microbiology and Biotechnology
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• v.22 no.10
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• pp.1446-1451
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• 2012

Levodopa or L-3,4-dihydroxyphenylalanine (L-DOPA) is the precursor of the neurotransmitter dopamine. L-DOPA is a famous treatment for Parkinson's disease symptoms. In this study, electroenzymatic synthesis of L-DOPA was performed in a three-electrode cell, comprising a Ag/AgCl reference electrode, a platinum wire auxiliary electrode, and a glassy carbon working electrode. L-DOPA had an oxidation peak at 376 mV and a reduction peak at -550 mV. The optimum conditions of pH, temperature, and amount of free tyrosinase enzyme were pH 7, $30^{\circ}C$, and 250 IU, respectively. The kinetic constant of the free tyrosinase enzyme was found for both cresolase and catacholase activity to be 0.25 and 0.4 mM, respectively. A cyclic voltammogram was used to investigate the electron transfer rate constant. The mean heterogeneous electron transfer rate ($k_e$) was $5.8{\times}10^{-4}$ cm/s. The results suggest that the electroenzymatic method could be an alternative way to produce L-DOPA without the use of a reducing agent such as ascorbic acid.

• Molecules and Cells
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• v.46 no.9
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• pp.538-544
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• 2023

The formation of uniform vitreous ice is a crucial step in the preparation of samples for cryogenic electron microscopy (cryo-EM). Despite the rapid technological progress in EM, controlling the thickness of vitreous ice on sample grids with reproducibility remains a major obstacle to obtaining high-quality data in cryo-EM imaging. The commonly employed classical blotting process faces the problem of excess water that cannot be absorbed by the filter paper, resulting in the formation of thick and heterogeneous ice. In this study, we propose a novel approach that combines the recently developed nanowire self-wicking technique with the classical blotting method to effectively control the thickness and homogeneity of vitrified ice. With simple procedures, we generated a copper oxide spike (COS) grid by inducing COSs on commercially available copper grids, which can effectively remove excess water during the blotting procedure without damaging the holey carbon membrane. The ice thickness could be controlled with good reproducibility compared to non-oxidized grids. Incorporated into other EM techniques, our new modification method is an effective option for obtaining high-quality data during cryo-EM imaging.

• The Journal of the Korea Contents Association
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• v.2 no.2
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• pp.42-46
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• 2002

Transfer of much informations or document necessitated between corporation or corporation and customer by fast growth of electronic commerce. So, it is acting by important success urea that make and manage standard of information in electronic commerce. It was work that work that make standard of information electron catalogue system or EDI environment is very difficult before XML comes out and expense costs much. But, it became easy that make standard of information by XML's entrance on the stage that have advantages of SGML and HTML Specially, it is very suitable that electronic commerce inflects XML as field that heterogeneous system exists and standardization is required urgently. That is, XML is big advantage in side that make out side that is and normalized document because store information in standard form that is applied well under heterogeneous system environment because do web environment by basis interface and can be used efficiently to transmit. Treatise that see hereupon could assume beforehand in browser control using XSLT. And using dynamic DLL XML catalogue edit system design and implementation.

• Bulletin of the Korean Chemical Society
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• v.15 no.12
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• pp.1042-1045
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• 1994

A thin film of silver ferricyanide (Ag$_3$Fe(CN)$_6$) on a platinum or gold substrates can be reduced electrochemically to the salt of silver ferrocyanide in potassium nitrate solution. The color of these films are orange and these films are shown to be electrochromic. The voltammogram is shown the asymmetry of the oxidation compared to the reduction wave under various supporting electrolytes. The standard heterogeneous electron-transfer rate for these films and bare Pt electrode were 0.49 ${\times}$ l0$^{-2}$ and 1.30 ${\times}$ l0$^{-2}$ cm/s, respectively, obtained using a rotating disc electrode. Rough D$_0$ values, evaluated from the Levich equation, for Fe(CN)$_6^{3-/4-}$ at both SF thin film and a bare Pt disc electrode were shown as 1.2l ${\times}$ l0-6 and 0.94 ${\times}$ l0$^{-6}$ cm$^2$/s, respectively. The conductivities, as determined from the slops of the i-V curves for a ca. 1 mm sample for dried SF potassium rich and deficient bulk samples pressed between graphite electrodes, were 9.34 ${\times}$ l0$^{-9}$ and 5.80 ${\times}$ l0$^{-9}$ (${\Omega}$${\cdot}$cm)$^{-1}$, respectively.

• Journal of Embryo Transfer
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• v.33 no.4
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• pp.281-286
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• 2018

Zona pellucida (ZP), a primarily representative coat of mammalian egg and embryo, has an extremely heterogeneous morphology during different developmental stages. The objective of the present study was to compare the morphological changes of the ZP surface of immature, in vitro and in vivo matured canine oocytes by using scanning electron microscopy (SEM). Canine ovaries were collected from local veterinary hospitals to recover immature oocytes. The ovaries were sliced and the released cumulus oocyte complexes (COCs) were washed with TL-HEPES. The selected COCs were randomly divided into two groups, first group was processed immediately at immature state and the second group was processed 72 h after in vitro maturation, and compared with in vivo derived oocytes. Oocytes were fixed, critical point dried and examined under SEM. The diameters of oocyte and outer holes of the ZP were measured on a total of 249 oocytes; the results were analyzed using One-way ANOVA. Our results showed that, the diameter of immature oocytes significantly differed (p < 0.05) from that of in vivo matured oocytes ($79.60{\pm}0.77{\mu}m$ vs. $101.46{\pm}1.07{\mu}m$, respectively). Similarly, a significant difference (p < 0.05) in the diameters between those of in vitro and in vivo matured oocytes were found ($79.51{\pm}2.36{\mu}m$ vs. $101.46{\pm}1.07{\mu}m$, respectively). Moreover, the diameters of the outer holes of the ZP were significantly (p < 0.05) larger in in vivo matured ($1.48{\pm}0.42{\mu}m$) than in vitro matured for 72 and immature oocytes ($1.10{\pm}0.16$ and $0.43{\pm}0.12{\mu}m$, respectively). Taken together, these data indicates that the ZP surface is related to oocyte maturity in canine.

• Journal of the Korean Electrochemical Society
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• v.11 no.2
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• pp.105-108
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• 2008

In the recent years, increasing interests are being focused on the rational functionalization of the CNTs by some creative methods. However, the considerable toxicity of CNT is still a controversialissue and limits its biological application. To improve the biocompatibility of CNT, in this work we prepared CNT-$TiO_2$ nanocomposites with CNT and organic titanium precursors. Our observations demonstratethat the modified interface could accelerate the heterogeneous electron transfer rates and thusenhance the relevant detection sensitivity, suggesting its potential application as the new strategy for the development of the biocompatible and multi-signal responsive biosensors for the early diagnosis of cancers.

• Journal of Korea Foresty Energy
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• v.23 no.1
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• pp.45-68
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• 2004

The word of lignin is derived from the Latin word 'ligum' meaning wood. Lignin is complex polymer consisting of coniferyl alcohol, sinapyl alcohol and p-coumaryl alcohol unit and has an amorphous, three dimensional network structure which is hard to be hydrolyzed by acid. Lignin is found in the cell wall of plants lignified. The mode of polymerization of these alcohols in the cell wall lead to a heterogeneous branched and cross-linked polymer in which phenyl propane units are linked by carbon-carbon and carbon-oxygen bonds. This polymerization of precursors, p-coumaryl alcohol, coniferyl alcohol and sinapyl alcohol to lignin is formed by enzymic dehydrolyzation. The reaction is initiated by an electron transfer which results in the formation of resonance-stabilized phenoxy radical. The combination of these radicals produces a variety of dimers, trimers and oligomers and so on. Lignin research has been divided into basic and practical application field. The basic studies contains biosynthesis, chemical structure, distribution in the cell wall and reactivity by reductants, oxidants and organic solvents. The application research will be approached the reaction of lignin in various pulp making involving pulp bleaching and its effect on pulp qualities. Lignin also will be studied for the production of fine chemicals, polymer products and the conservation into an energy source like petroleum oil because the amount of lignin produced in pulp making process is more than 51,000,000 tons per year in the world. Both basic and application research must lay emphasis on the development for the utilization of lignin and the pulping process. But these researches can not be completed without understanding lignin structure containing functional groups. Therefore, this paper was focused on the review of lignin formulation which has been studied since 1948 in chronological order. This review was based on monomers, dimers, trimers and tetramers of phenyl propane unit structures which were isolated and identified by different methods from various wood.ious wood.