• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.1
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• pp.26-31
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• 2006

The saccharogenic liquid (SFW) obtained by the enzymatic saccharification of food wastes was used as a medium for production of bacterial cellulose (BC). The enzymatic saccharification of food wastes was carried out by the cultivation supernatant of Trichoderma harziaum FJ1 culture. Acetobacter xylinum KJ1 was employed for the BC production culture. The physical properties, such as polymerization, crystallinity, Young's modulus, and tensile strength, of BCs produced by three culture methods: the static cultures using HS (Hestrin-Schramm) as a reference medium (A) or the SFW medium (B), the shaking culture (C) or the air circulation culture (D) using the SFW medium, were investigated. The degrees of polymerization of BCs produced under the different culture conditions (A-D) showed 11000, 9500, 8500, and 9200, respectively. Young's modulus was 4.15, 5.0, 4.0, and 4.6 GPa, respectively. Tensile strength was 124, 200, 80, and 184 MPa, respectively. All of the BC had a form of cellulose I representing pure cellulose. In the case of the shaking culture, the degree of crystallinity was 51.2%, the lowest degree. Under the other culturing conditions, the trend should remain in the range of 89.7-84%. Overall, the physical properties of BC produced from SFW were similar to those of BC from HS medium, a commercial complex medium, and BC production by the air circulation culture mode brought more favorable results in terms of the physical properties and its ease of scale-up. Therefore, it is expected that a new BC production method, like air circulation culture using SFW, would contribute greatly to BC-related manufacturing.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.2
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• pp.47-53
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• 2018

Nowadays, additive manufacturing (AM) technology is a promising process to fabricate complex shaped devices applied in medical and dental services. Among the AM processes, a DLP (digital light processing) type 3D printing process has some advantages, such as high precision, relatively low cost, etc. In this work, we propose a simple method to fabricate precise dental models using a DLP 3D printer. After 3D printing, a part is commonly post-cured using secondary UV-curing equipment for complete polymerization. However, some shrinkage occurs during the post-curing process, so we adaptively control the UV-exposure time on each layer for over- or under-curing to change the local shape-size of a part in the DLP process. From the results, the shrinkage amounts in the post-curing process vary due to the UV-dose in 3D printing. We believe that the proposed method can be utilized to fabricate dental models precisely, even with a change of the 3D CAD model.

• Microbiology and Biotechnology Letters
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• v.46 no.1
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• pp.45-50
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• 2018

The chitosanase gene (btbchito) of Bacillus thuringiensis BMB171 was cloned and heterologously expressed in the yeast Pichia pastoris. After purification, about 300 mg of recombinant chitosanase was obtained from the 1-1 culture medium with a specific activity of 240 units/mg. Results determined by the combined use of thin layer chromatography (TLC) and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) showed that the chitooligosaccharides (COSs) obtained by chitosan (N-deacetylated by 70%, 80%, and 90%) hydrolysis by rBTBCHITO were comprised of oligomers, with degrees of polymerization (DP) mainly ranging from trimers to heptamers; high molecular weight chitopentaose, chitohexaose, and chitoheptaose were also produced. Hydrolysis products was also deduced using MS since the COSs (n) are complex oligosaccharides with various acetyl groups from one to two, so the non-acetyl COSs (GlcN)n and COSs with more acetyls (> 2) were not detected. The employment of this method in the production of high molecular weight COSs may be useful for various industrial and biological applications, and the activity of chitosanase has great significance in research and other applications.

• Bulletin of the Korean Chemical Society
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• v.24 no.1
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• pp.27-31
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• 2003

A Polythiophene-quinoline/glassy carbon (PTQ/GC) modified electrode was developed for the determination of trace mercury in industrial waste water, natural water, soil, and other media. The electrode was prepared by the cyclic voltammetric polymerization of thiophene and quinoline on glassy carbon (GC) electrode by the potential application from -0.6 V to +2.0 V (50 mV/sec) in a solution of 0.1 M thiophene, quinoline and tetrabutyl ammonium perchlorate (TBAP) in acetonitrile. Optimum thickness of the polymer membrane on the GC electrode was obtained with 20 repeated potential cyclings. The redox behavior of Cu(Ⅱ) and Hg(Ⅱ) were almost identical on this electrode. The addition of 4-(2-pyridylazo)resorcinol (PAR) to the solution containing Cu(Ⅱ) and Hg(Ⅱ) allowed the separation of the components due to the formation of the Cu(Ⅱ)-PAR complex reduced at -0.8V, which was different from the Hg(Ⅱ) reduced at -0.5 V on a saturated calomel electrode (SCE). The calibration graph of Hg(Ⅱ) shows good linear relationship with the correlation factor of 0.9995 and the concentration gradient of 0.33 ㎂/㎠/ppb down to 0.4 ppb Hg. The method developed was successfully applied to the determination of mercury in samples such as river, waste water, and sea water.

• International Journal of Industrial Entomology and Biomaterials
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• v.48 no.3
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• pp.139-146
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• 2024

For stable silkworm breeding and high-quality sericulture product production, the detection of Pebrine disease in silkworm eggs is critical. Current diagnostic methods can be timeconsuming and complex. This study aimed to develop a simplified and rapid diagnostic method using loop-mediated isothermal amplification (LAMP) technology to detect pebrine infection in silkworm mother moths. Eight primer candidates targeting the ribosomal gene region of microsporidia were designed and evaluated for specificity and detection sensitivity. A simplified nucleic acid extraction method was established, and isothermal amplification was performed using the selected primers. Of these, primers ID30 and ID45 showed no polymerization, while ID5, ID18, and ID76 exhibited nonspecific reactions, making them unsuitable. Primers ID1, ID6, ID45, and ID82 successfully amplified DNA only in the presence of pebrine, with ID82 demonstrating the best reproducibility and sensitivity, detecting as low as 2.5 pg/ul of DNA through electrophoresis and 5 pg/ul via a colorimetric change with phenol red. The entire process, from nucleic acid extraction to detection, was completed within 60 min. The use of the ID82 primer set in LAMP technology offers a promising and efficient approach for the rapid diagnosis of pebrine disease, potentially enhancing quality control in sericulture.

• Analytical Science and Technology
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• v.8 no.1
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• pp.1-7
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• 1995

Spectrophotometric determination of U(VI) and Th(IV) by Flow injection method is described. Chrome Azurol S forms water soluble complexes with U(VI) and Th(IV) in the presence of cethyltrimethylammonium bromide. The maximum adsorption of U(VI) and Th(IV) complexes are at 600nm with molar absorptivity of $2.3{\times}10^5Lmol^{-1}cm^{-1}$ and 611nm with molar absorptivity of $3.8{\times}10^5Lmol^{-1}cm^{-1}$ in acetate buffer medium having pH 5.0 and 5.5. The calibration curves of U(VI) and Th(IV) are linear over the range of 0.1~0.8ppm and the correlation coefficients are ca. 0.9960 and 0.9930 respectively. The detection limits(S/N) are 20ppb for U(VI) and 15ppb for Th(IV). The relative standard deviation are ${\pm}1.8%$ for U(VI) and ${\pm}2.1%$ for Th(IV). The sample throughput was ca. $50hr^{-1}$.