• Environmental Engineering Research
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• v.14 no.1
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• pp.63-67
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• 2009

Escherichia coli K-12 (E. coli K-12) is a representative indicator globally used for distinguishing and monitoring dynamic fates of pathogenic microorganisms in the environment. This study investigated how to most critically quantify lacZ ($\beta$-galactosidase) gene in E. coli K-12 by two different real-time polymerase chain reaction (real-time PCR) in association with three different DNA extraction practices. Three DNA extractions, i.e., sodium dodecyl sulfate (SDS)/proteinase K, magnetic beads and guanidium thiocyanate (GTC)/silica matrix were each compared for extracting total genomic DNA from E. coli K-12. Among them, GTC/silica matrix and magnetic beads beating similarly worked out to have the highest (22-23 ng/${\mu}L$) concentration of DNA extracted, but employing SDS/proteinase K had the lowest (10 ng/${\mu}L$) concentration of DNA retrieved. There were no significant differences in the quantification of the copy numbers of lacZ gene between SYBR Green I qPCR and QProbe-qPCR. However, SYBR Green I qPCR obtained somewhat higher copy number as $1{\times}10^8$ copies. It was decided that GTC/silica matrix extraction or magnetic beads beating in combination with SYBR Green I qPCR can be preferably applied for more effectively quantifying specific gene from a pure culture of microorganism.

• Journal of Microbiology and Biotechnology
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• v.11 no.5
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• pp.890-894
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• 2001

The isolation of genomic DNA from mammalian cells is usually performed by cell lysis followed by protein digestion, extraction, and finally, ethanol precipitation of the chromosomal DNA. However, in the case of large sample numbers or when only small amounts of starting materials are available, such conventional methods are not efficient and are cumbersome to be applied. Some alternative methods have been described as well as having commercial DNA isolation kits to be available, nevertheless, there is room left for much improvement. In the present study, a novel method is introduced, where it simplifies conventional protocols by omitting some time-consuming steps such as protease incubation or DNA precipitation and its resuspension. Using paramagnetic silica resins, the genomic DNA was purified over a magnetic field, and the bound DNA was eluted with a low-salt buffer. The fidelity and effectiveness of this novel method was determined by using normal and apoptotic cells as a starting material and then compared to other protocols. The high speed and convenience along with its high efficiency in detecting apoptotic chromosomal DNA will prove this method to be an improved alternative in the isolation of genomic DNA from mammalian cells.

• Journal of the Mineralogical Society of Korea
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• v.22 no.3
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• pp.191-197
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• 2009

It is very important to raise the purity of silica for manufacturing metallurgical-grade silicon because the purification of silicon in the smelting process is very difficult. In present study, the silica sand which is obtained from Vietnam was mineralogically analyzed. Based on the results, a novel process to separate impurities from the silica sand was developed, which consisted of classification, specific gravity and magnetic separation steps. Using the developed process, high-grade silica sand concentrate containing over 99.8 wt% $SiO_2$ was prepared, being suitable for manufacturing the metallurgical-grade silicon.

• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.196-201
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• 2006

Silica(SiO2) nanoparticles are used as additives in plastics and rubbers to improve mechanical, electrical, magnetic properties and optical material. Silica nanoparticles were synthesized by the gas phase thermal oxidation of several kinds of precursors in many types of reactor. Diffusion flame reactor has some advantages compared with other types of reactors. In this study, we investigated the generation of silica nanoparticles on the effect of residence time by tetraethylothosilicate(TEOS) in a turbulent diffusion flame reactor controlled by providing reactant flowrate and reactor geometry affect particle morphology, particle size and particle size distribution. To determine the flame residence time, flame length should be determined which was examined by ICCD image. Particle size, distribution and morphology were performed with TEM.

• Journal of Applied Biological Chemistry
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• v.64 no.4
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• pp.363-368
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• 2021

The fruits of tomato (Lycopersicon esculentum) were extracted with 70% aqueous methanol (MeOH) and the concentrates were partitioned into ethyl acetate (EtOAc), n-butanol (n-BuOH), and water (H₂O) fractions. The repeated silica gel (SiO₂) and octadecyl silica gel column chromatographies for the EtOAc fraction, whose activity was confirmed, led to isolation of one flavone compound. Nuclear magnetic resornance, infrarad spectroscopy, and mass spectroscopy (MS) revealed the chemical structure of the isolated compound, 5,7,3'-trihydroxy-6,4',5'-trimethoxyflavone (1). LC-MS/MS analysis determined the content level of compounds 1 in the MeOH extract to be 4.02±0.12 ㎍/mg and in the TME-10 fraction to be 0.96±0.03 ㎍/mg. Through this study, the antioxidantive capacity was confirmed by demonstrating that the L. esculentum extract and their fractions showing an increase in glutathione mean and a decrease in glutathione heterogeneity uniformly raises the intracellular glutathione level.

• Polymer(Korea)
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• v.36 no.5
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• pp.668-676
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• 2012

In this study, we modified silica nanoparticles with bis[3-(trimethoxysilyl)propyl]amine (BTMA) silane coupling agent to introduce secondary amino groups on the silica surface. After modification of silica, we investigated effects of different types of (meth)acrylate group containing monomers on the Michael addition reaction to introduce reactive (meth)acrylate groups on the BTMA modified silica surface. We used two kinds of (meth)acrylate monomers, trimethylolpropane ethoxylate triacrylate (TMPET) which has three identical acrylate groups, and 3-(acryloyloxy)-2-hydroxypropyl methacrylate (AHM) which has one acrylate and one methacrylate group. We used fourier transform infrared spectroscopy (FTIR), elemental analysis (EA) and solid state cross-polarization magic angle spinning (CP/MAS) nuclear magnetic resonance spectroscopy (NMR) to understand reactions between NH groups on the silica surface with (meth)acrylate groups of TMPET and AHM monomers. We found almost complete Michael addition reaction between all three acrylate groups of TMPET with NH groups on the BTMA modified silica. But, for the AHM treatment of BTMA modified silica, we found Michael addition reaction occurred only between acrylate groups of AHM and NH groups of silica surface, not between methacrylate groups of AHM and NH groups of BTMA modified silica surface.

• Journal of the Korean Magnetics Society
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• v.8 no.1
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• pp.1-5
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• 1998

Acicular Fe-Co alloy particles are one of the candidates for high-density magnetic recording media. We examined the effects of Co additions on the magnetic properties of Fe-Co alloy particles by using M$\'{o}$ssbauer spectroscopy, TEM, and X-ray diffraction. Acicular $Fe_n$Co (n=5, 4, 3, 2) alloy particles coated with silica, were prepared by a chemical coprecipitation method and subsequent H $_2$ reduction. The crystal structure was found to be cubic in all n ranges. The lattice constant $a_0$ decreases with increasing Co contents. Analysis of $^{57}Fe$ M\'{o}$ssbauer effect data in terms of the local configurations of Co atoms has permitted the influence of magnetic hyperfine interactions to be monitored.

• Advances in environmental research
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• v.4 no.2
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• pp.69-81
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• 2015

A new magnetite-silica core/shell nanocomposite ($Fe_3O4@nSiO_2@mSiO_2$) was synthesized and functionalized with trimethylchlorosilane (TMCS). The prepared nanocomposite was used for the removal of diesel oil from aqueous media. The characterization of magnetite-silica nanocomposite was studied by X-ray diffraction (XRD), Fourier transform infrared (FTIR), transmission electron microscopy (TEM), surface area measurement, and vibrating sample magnetization (VSM). Results have shown that the desired structure was obtained and surface modification was successfully carried out. FTIR analysis has confirmed the presence of TMCS on the surface of magnetite silica nanocomposites. The low- angle XRD pattern of nanocomposites indicated the mesoscopic structure of silica shell. Furthermore, TEM results have shown the core/shell structure with porous silica shell. Adsorption kinetic studies indicated that the nanocomposite was able to remove 80% of the oil contaminant during 2 h and fit well with the pseudo-second order model. Equilibrium studies at room temperature showed that the experimental data fitted well with Freundlich isotherm. The magnetic property of nanocomposite facilitated the separation of solid phase from aqueous solution.

• Polymer(Korea)
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• v.36 no.3
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• pp.372-379
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• 2012

In this study, we treated silica nanoparticles with bis[3-(trimethoxysilyl)propyl]amine (BTMA) silane coupling agent to modify their surfaces. We investigated the effects of BTMA hydrolysis time, BTMA concentration and BTMA treatment time on the degree of silanization reaction of silica nanoparticles. We used Fourier transform infrared spectroscopy (FTIR), elemental analysis (EA) and solid state cross-polarization magic angle spinning (CP/MAS) nuclear magnetic resonance spectroscopy (NMR) to obtain quantitative data. We found the decrease of isolated Si-OH peak intensity at 3747 $cm^{-1}$ and the increase of $-CH_2 $stretching and bending peaks with increasing hydrolysis time, concentration and treatment time of BTMA. EA analysis results also supported this trend. We found a strong effect of BTMA concentration on the degree of silanization of the silica particles, but weak effects of the hydrolysis time and the treatment time.

• Applied Chemistry for Engineering
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• v.33 no.1
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• pp.113-118
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• 2022

Multifunctional nanomaterials based on mesoporous silica nanoparticles (MSN) and metal oxide nanocrystals are among the most promising materials for theragnosis because of their ease of modification and high biocompatibility. However, the preparation of multifunctional nanoparticles requires time-consuming multistep processes. Herein, we report a simple one-pot synthesis of multifunctional Mn₃O₄/mesoporous silica core/shell nanoparticles (Mn₃O₄@mSiO₂) involving the temporal separation of core formation and shell growth. This simple procedure greatly reduces the time and effort required to prepare multifunctional nanoparticles. Despite the simplicity of the process, the properties of nanoparticles are not markedly different from those of core/shell nanoparticles synthesized by a previously reported multistep process. The Mn₃O₄@mSiO₂ nanoparticles are biocompatible and have potential for use in optical imaging and magnetic resonance imaging.