• Journal of Microbiology and Biotechnology
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• v.10 no.2
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• pp.251-257
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• 2000

Chitin synthases are identified as key enzymes of chitin biosynthesis in most of the fungi. Among them, chitin synthase II has been reported to be and essential enzyme in chitin biosynthesis, and exists as a membrane-bound form. To search and screen new antifungal agents from natural resources to inhibit chitin synthase II, the assay conditions were established using the enzyme isolated from Saccharomyces cerevisiae ECY38-38A(pAS6) that overproduces only chitin synthase II. This enzyme was activated only by partial proteolysis with trypsin. Its actibity reached the maximum at $80{\;}\mu\textrm{g}/ml$ of trypsin and was strongly stimulated by 2.0 mM $Co^{2+}$, 1.0 nM UDP-[$^{14}C$]-GicNAc, and 32 mM free-GlcNAc. Under these assay conditions, the highest chitin synthase II activity was observed by incubation at $30^{\circ}C$ for 90 min. However, and extremely narrow range of organic solvents up to as much as 25% of DMSO and 25% of MeOH was useful for determining optimal assay conditions. After a search or potent inhibitors of chitin synthase II from natural resources, prodigiosin was isolated from Serratia marcescens and purified by solvent extration and silica gel column chromatographies. The structure of prodigiosin was determined by UV, IR, Mass spectral, and NMR spectral analyses. Its molecular weight and formula were found to be 323 and $C_{20}H_{25}N_{3}O$, respectively. Prodigiosin ingibited chitin synthase II by 50% at the concentration of $115{\;}\mu\textrm{g}/ml$.

• Microbiology and Biotechnology Letters
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• v.45 no.3
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• pp.200-208
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• 2017

Actinobacteria are prolific producers of a large number of natural products with diverse biological activities. In the present study, an actinobacterium isolated from sunflower rhizosphere soil sample collected from Medak, Andhra Pradesh, South India was identified as Amycolatopsis thermoflava strain SFMA-103. A pigmented secondary metabolite in culture broth was extracted by using methanol and it was further purified by silica gel column chromatography with methanol-chloroform solvent system. Structural elucidation studies based on UV-visible, 1D and 2D-NMR, FT-IR, and mass spectroscopic analyses confirmed the structure as 1-methoxy-3-methyl-8-hydroxy-anthraquinone. It showed significant in vitro anticancer activity against lung cancer and lymphoblastic leukemia cells with $IC_{50}$ values of 10.3 and $16.98{\mu}M$, respectively. In addition, 1-methoxy-3-methyl-8-hydroxy-anthraquinone showed good free radical scavenging activity by DPPH method with an $EC_{50}$ of $18.2{\mu}g/ml$. It also showed other promising superoxide radical scavenging, nitric oxide radical scavenging and inhibition of lipid peroxidation activities. This is a first report of anti-proliferative and antioxidant activities of 1-methoxy-3-methyl-8-hydroxy-anthraquinone isolated from A. thermoflava strain SFMA-103 which may find potential application in biotechnological and pharmaceutical fields.

• Korean Journal of Pharmacognosy
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• v.39 no.3
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• pp.233-236
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• 2008

In order to find the antioxidative components, fractionation of Cyperus amuricus (Cyperaceae) methanol extract was performed by measuring the DPPH (1,1-diphenyl-2-picrylhydrazyl) scavenging effect. Three compounds, 3,4-dimethoxy benzoic acid (1), 4-hydroxybenzoic acid (2), and piceatannol (3) were isolated from the active ethylacetate soluble fraction of C. amuricus through repeated silica gel and Sephadex LH-20 column chromatography. Among them, compound 3 showed the significant antioxidative effect on DPPH free radical scavenging test. These compounds are reported for the first time from this plant.

• Magazine of the Korea Concrete Institute
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• v.6 no.3
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• pp.201-214
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• 1994

The fracture process zone in concrete is a region ahead of a traction-free crack, in which two major mechanisms, microcracking and bridging, play important roles. The toughness due to bridging is dominant compared to toughness induced by microcracking, so that the bridging is dominani: mechanism governing the fracture process of concrete. Fracture mechanics does work for concrete provided that the fracture process zone is being considered, so that the development of model for the fracture process zone is most important to describe fracture phenomena in concrete. In this paper the bridging zone, which is a part of extended rnacrocrack with stresses transmitted by aggregates in concrete, is modelled by a Dugdale-Barenblatt type model with linear tension-softening curve. Two finite element techniques are shown for the analysis of progressive cracking in concrete based on the discrete crack approach: one with crack element, the other without crack element. The advantage of the technique with crack element is that it dees not need to update the mesh topology to follow the progressive cracking. Numerical results by the techniques are demonstrated.

• Journal of the Korean Chemical Society
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• v.35 no.5
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• pp.534-538
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• 1991

A procedure for spectrophotometric determination of traces of boron in high-purity trichlorosilane (TCS) is proposed utilizing an adsorptive separation. NaCl is chosen as an Lewis base adsorbent which forms a complex with boron compounds in TCS, and is well dissolved in sulfuric acid-quinalizarin color-forming agent without causing an interference in colorimetric measurements. The proposed adsorptive separation method is free from the formation of silica gel and gas bubbles during the analysis of TCS. The method reveals that the boron concentration in a semiconductor grade TCS is 6.1 ${\mu}$g/l within the standard deviation of ${\pm}$20%. On the other hand, the boron concentration of the purified TCS which is separated from NaCl-boron compounds complex is reduced to 0.2 ${\mu}$g/l, showing the efficient applicability of NaCl to the adsorptive separation. The effectiveness of NaCl for the removal of boron in TCS purification is also described in comparison with other well-known adsorbents.

• Journal of the Korean Wood Science and Technology
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• v.29 no.3
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• pp.112-122
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• 2001

Laccase enzymes from Cerrena unicolor and Trametes versicolor were immobilized on the activated glass beads (CPG), silica gel (SG) and soil (SL). The heterogeneous matrices were activated by ${\gamma}$-aminopropyltriethoxysilane (APTES) and glutaraldehyde (GA), and their surfaces were coated by keratin (KER) on activated or non-activated CPG, SG and SL. The laccase activities were tested in the aqueous solution for the native and immobilized preparations using different pH and temperature conditions. By keratin coating on supports, in the cases of CPG-KER and SL-KER, the immobilization yield was increased from about 80% to 90%. Moreover, much less protein was immobilized in keratin coated matrices than in inorganic ones alone (e.g. on CPG-KER 57.6%, whereas on CPG alone 80.6%). Laccase immobilization on keratin coated inorganic matrices was generally more effective than that of non-coated matrices. Concerned to pH dependency, the optima pH for immobilized laccases generally shifted towards to higher values, 5.5-5.8 and even 5.9 in the case of keratin for C. unicolor and from 5.3 to 5.7 for T. versicolor, respectively, and decreased less gradually both in acidic and alkaline regions. The immobilized laccase was more stable against thermal denaturation. This seems particularly true at $75^{\circ}C$ in the case of C. unicolor, where the activity of immobilized enzyme is > 50% higher than that of the free enzyme. For T. versicolor the respective values were $65^{\circ}C$, and 50%.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2008.05a
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• pp.1-46
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• 2008

The ability to control filler performance and fines retention is vital in the development of both filled and non filled grades, respectively. This is very important when achieving the desired sheet structure necessary to maximize machine performance and end user demands. A narrow balance exists in attaining the desired retention and formation particularly in systems with heavier ash loads and producing paper and paper board on higher speed high shear equipment. A new generation of both cationic and anionic micropolymer technologies has been developed. These water based chemistries are volatile organic compound (VOC) and alkyphenol ethoxylate (APE) free. When these novel micropolymers are applied with linear poly-acrylamide or in conjunction with inorganic microparticle technologies (such as silica or swellable minerals), substantial increases in drainage, fibre retention and ash retention are observed. These improvements have been observed not only in high filled wood and non wood containing grades such as fine paper and super calendared sheets (SCA), but also in low filled newsprint grades. Of particular note is the drainage improvement seen with the application of the cationic micropolymers in unbleached packaging grades with poly-acrylamide.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.6
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• pp.770-775
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• 2014

The green microalga of the genus Nannochloropsis (class Eustigmatophyceae) is a leading candidate for biofuel production due to its ability to accumulate high oil content (28.7% of cellular ash-free dry weight). We investigated the anti-inflammatory and anticancer activities of sterol-rich fraction from nannochloropsis oculata n-hexane (NOH) extract after saponification of the microalga. Among the fractions with n-hexane, chloroform and ethyl acetate, the n-hexane fraction showed the highest anti-inflammatory activity in LPS-stimulated RAW 264.7 macrophage as well as anticancer activity against human leukemia HL-60 cells without the cytotoxity. And the sterol-rich fraction was obtained from the n-hexane fraction by open silica column under the gradient solvent condition with 100% hexane (1L), hexane : ethyl acetate (20 : 1, 10 : 1, 5 : 1, 1 : 1, v/v). Among the four fractions (NOH-1~4), especially NOH-1 contained the highest content of sterols. NOH1 showed the highest HL-60 (about 85%) and NO inhibitory activities at the concentration of $100{\mu}g/mL$. These results demonstrated that the sterol-rich fraction from N. oculata might be a useful candidate as anti-inflammatory and anticancer agents for anti-inflammatory and anticancer activity.

• Korean Journal of Veterinary Research
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• v.37 no.1
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• pp.195-202
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• 1997

A method for the isolation by matrix solid phase dispersion method and liquid chromatographic determination of enrofloxacin and ciprofloxacin in pork muscle tissue is presented. Blank or enrofloxacin and ciprofloxacin spiked samples(0.5g) containing 0.05g oxalic acid were blended with $C_{18}$(octadecylsilyl derivatized silica) packing material. After homogenization, $C_{18}$/muscle tissue matrix was transferred to glass column made from 10ml glass syringe and filter paper, and compressed to 4~4.5ml volume. A column was washed with 8ml of hexane and dried under vacuum. Interfering materials were removed by ethylacetate 8ml and dried, following which enrofloxacin and ciprofloxacin were eluted with 8ml of methanal under gravity. The eluate containing enrofloxacin and ciprofloxacin wase free from interfering compound when analysed by HPLC with UV detection at 278nm. Enrofloxacin and ciprofloxacin showed linear response with UV detector at the range of $0.05{\sim}1.0{\mu}g/ml$ and eluted within 5ml elution volume of methanol from the matrix. Fortified sample containing 0.05g oxalic acid represented more good recoveries than that of control sample. Average percentages of enrofloxacin and ciprofloxacin were $93.30{\pm}4.56%$ and $91.84{\pm}4.17%$, respectively, for the concentration range(0.05, 0.1, 0.25, 0.5 and $0.75{\mu}g/g$). The interassay variability of enrofloxacin was $6.02{\pm}5.33%$ with an intra-assay variability of 4.89% and $6.75{\pm}2.68%$ with 4.54% for ciprofloxacin. Detection limit of enrofloxacin and ciprofloxacin was $0.030{\mu}g/g$ in the spiked sample.

• Korean Chemical Engineering Research
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• v.45 no.6
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• pp.611-618
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• 2007

We demonstrate the sol-gel coating technique of colloidal clusters for producing hollow micro-particles with complex morphologies. Cross-linked amidine polystyrene (PS) microspheres were synthesized by emulsifier-free emulsion copolymerization of styrene and divinylbenzene. The amidine PS particles were self-organized inside toluene-in-water emulsion droplets to produce large quantities of colloidally stable clusters. These clusters were coated with thin silica shell by sol-gel reaction of tetraethylorthosilicate (TEOS) and ammonia, and the organic polystyrene cores were removed by calcination at high temperature to generate nonspherical hollow micro-particles with complex morphologies. This process can be used to prepare hollow particles with shapes such as doublets, tetrahedra, icosahedra, and others.