• Composites Research
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• 제26권5호
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• pp.322-327
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• 2013

탄소섬유강화 SiC기지상 복합재는 우수한 산화저항성과 우수한 열충격저항성을 가진다. 그리고 이런 특성들은 탄소섬유강화복합재가 고온구조재로서 응용케하였다. 본 연구에서는 $C_f/SiC$ 복합재가 전구체 함침과 액상 함침이 동반된 열분해공정, Cyclohexene을 사용한 화학기상 경화공정을 통해 제조되었다. 최종 제조된 $C_f/SiC$ 복합재는 5회 함침을 통해 $0.43g/cm^3$ 밀도를 갖는 탄소섬유 프리폼에서 $1.76g/cm^3$의 밀도값을 나타내고 있다. 그리고 산화저항성 특성면에서 $C_f/SiC$ 복합재의 무게가 공기중 $1400^{\circ}C$에서 6시간 유지 후에 81%가 남았다. 결과적으로 Cyclohexene을 사용한 화학기상 경화공정은 효과적으로 높은 치밀화와 증가된 산화저항성을 보이고 있다.

• Bulletin of the Korean Chemical Society
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• 제32권7호
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• pp.2178-2182
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• 2011

Recently, the synthesis of ordered macroporous materials has received much attention due to its potential use as photonic band gap materials.$^1$ In this study, we have used the three-dimensional (3D) latex array template impregnated with benzenesulfonic acid (BSA), which is capable of catalyzing the reaction using tetraethyl orthosilicate (TEOS) as a precursor and distilled water. The polystyrene (PS) templates were reacted with TEOS in $scCO_2$ at 40 $^{\circ}C$ and at 80 bar. In the reactor, TEOS was filtrated into the PS particle lattice. After the reaction, porous silica materials were obtained by calcinations of the template. The stability test of the PS template in pure $CO_2$ was conducted before the main experiment. Scanning electron microscopy (SEM) images showed that the reaction in $scCO_2$ takes place only on the particle surface. This new method using $scCO_2$ has advantages over conventional sol-gel processes in its capability to control the fluid properties such as viscosity and interfacial tension. It has been found that the reaction in $scCO_2$ occurs only on the particle surface, making the proposed technique as more rapid and sustainable method of synthesizing inverse opal materials than conventional coating processes in the liquid phase and in the vapor phase.

• 미생물학회지
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• 제48권1호
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• pp.37-41
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• 2012

본 연구에서는 sesquiterpene류의 생물학적 변환을 위한 생촉매로서 목재부후균을 선발하고 생물변환 가능성을 확인하였다. Sesquiterpene류 합성 전구체로 알려진 trans,trans-farnesol을 기질로 하여 총 19종의 목재부후균에 대해여 저항성 실험을 실시하였다. 기질의 농도를 달리하여 저항성 테스트를 실시하여 생물변환 가능성을 갖는 5종의 균주를 선발하였으며 선정된 균주를 이용하여 액체배지 조건에서 trans,trans-farnesol의 생물변환을 시도하였다. GC/MS를 이용하여 분석한 결과 Laetiporus sulphureus var. miniatus (jungh) Imaz, Coriolus versicolor (L. Fr). Prlar, Fomitopsis pinicola, Lampteromyces japonicas 등 4개의 균주에서 각각 nerolidol, eicosane, isoborneol, isocyclocitral 등의 대사산물을 확인할 수 있었다. 이와 같은 결과로 sesquiterpene류의 생물학적 변환을 위한 생촉매로서 목재부후균의 가능성을 확인하였다.

• 분석과학
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• 제30권6호
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• pp.379-389
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• 2017

In this study, we set up an analytical method that can be used for rapid and accurate determination of representative isoquinoline alkaloids in medicinal plants using UPLC-ESI-Q-TOF MS (ultra pressure liquid chromatography-electrospray ionization-quadrupole-time-of-flight mass spectrometry). The compounds were eluted on a C18 column with 0.1 % formic acid and acetonitrile, and separated with good resolution within 13 min. Each of the separated components was characterized by precursor ions (generated by ESI-Q-TOF) and fragment ions (produced by collision-induced dissociation, CID), which were used as a reliable database. We also performed method validation: analytes showed excellent linearity ($R^2$, 0.9971-0.9996), LOD (5-25 ng/mL), LOQ (17-82 ng/mL), accuracy (91.6-97.4 %) as well as intra- and inter-day precisions (RSD, 1.8-3.2 %). In the analysis of Chelidonium majus L., magnoflorine, coptisine, sanguinarine, berberine and palmatine were detected by matching retention times and characteristic fragment ion patterns of reference standards. We also confirmed that, among the quantified components, coptisine was present in the highest quantity. Furthermore, alkaloid profiling was carried out by analyzing the fragment ion patterns corresponding to peaks of unknown components. In this manner, protopine, chelidonine, stylopine, dihydroberberine, canadine, and nitidine were tentatively identified. We also proposed the molecular structure of the fragment ions that appear in the mass spectrum. Therefore, we concluded that our suggested method for the determination of major isoquinoline alkaloids by UPLC-Q-TOF can be useful not only for quality control, but also for rapid and accurate investigation of phytochemical constituents of medicinal plants.

• 한국대기환경학회지
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• 제33권1호
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• pp.54-63
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• 2017

Atmospheric nitrogen containing organic compounds(e.g. amino acids) has attracted considerable attention from the viewpoint of the oceanic biogeochemical cycle of nitrogen as well as the long range transfer. However, only a few measurements of organic nitrogen compounds have been conducted due to analytical difficulties. In this study, total of nine amino acids such as Glutamic acid, Histidine, Arginine, Tyrosine, Cystine, Valine, Methionine, Phenylalanine, Lysine have been analytically determined by Liquid Chromatography - Mass Spectrometry Mass Spectrometry (LC-MSMS). As results, Fragmentor Voltage (FV), Precursor Ion, Collision Energy, Product Ion related to individual amino acid compounds are shown. Based on the operational conditions, Lysine, Glutamine Acid, Tyrosine were analyzed during the China Oriented Smog Period. High concentrations of Lysine, Glutamine Acid, and Tyrosine are discussed with organic carbon (OC), elemental carbon (EC), and water soluble ions. The results can provide to understand the sources with aging process related to amino acids influenced by the long-range transport from the Yellow Sea area.

• The Korean Journal of Physiology and Pharmacology
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• 제18권2호
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• pp.155-161
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• 2014

Overexpression of amyloid precursor protein with the Swedish mutation causes abnormal hyperphosphorylation of the microtubule-associated protein tau. Hyperphosphorylated isoforms of tau are major components of neurofibrillary tangles, which are histopathological hallmarks of Alzheimer's disease. Protein phosphatase 2A (PP2A), a major tau protein phosphatase, consists of a structural A subunit, catalytic C subunit, and a variety of regulatory B subunits. The B subunits have been reported to modulate function of the PP2A holoenzyme by regulating substrate binding, enzyme activity, and subcellular localization. In the current study, we characterized regulatory B subunit-specific regulation of tau protein phosphorylation. We showed that the PP2A B subunit PPP2R2A mediated dephosphorylation of tau protein at Ser-199, Ser-202/Thr-205, Thr-231, Ser-262, and Ser-422. Down-regulation of PPP2R5D expression decreased tau phosphorylation at Ser-202/Thr-205, Thr-231, and Ser-422, which indicates activation of the tau kinase glycogen synthase kinase 3 beta ($GSK3{\beta}$) by PP2A with PPP2R5D subunit. The level of activating phosphorylation of the $GSK3{\beta}$ kinase Akt at Thr-308 and Ser-473 were both increased by PPP2R5D knockdown. We also characterized B subunit-specific phosphorylation sites in tau using mass spectrometric analysis. Liquid chromatography-mass spectrometry revealed that the phosphorylation status of the tau protein may be affected by PP2A, depending on the specific B subunits. These studies further our understanding of the function of various B subunits in mediating site-specific regulation of tau protein phosphorylation.

• Mass Spectrometry Letters
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• 제5권1호
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• pp.16-23
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• 2014

Liquid chromatography based mass spectrometry (LC-MS) is a key technology for analyzing highly complex and dynamic proteome samples. With highly accurate and sensitive LC-MS analysis of complex proteome samples, efficient data processing is another critical issue to obtain more information from LC-MS data. A typical proteomic data processing starts with protein database search engine which assigns peptide sequences to MS/MS spectra and finds proteins. Although several search engines, such as SEQUEST and MASCOT, have been widely used, there is no unique standard way to interpret MS/MS spectra of peptides. Each search engine has pros and cons depending on types of mass spectrometers and physicochemical properties of peptides. In this study, we describe a novel data process pipeline which identifies more peptides and proteins by correcting precursor ion mass numbers and unifying multi search engines results. The pipeline utilizes two open-source software, iPE-MMR for mass number correction, and iProphet to combine several search results. The integrated pipeline identified 25% more proteins in mouse epididymal adipose tissue compared with the conventional method. Also the pipeline was validated using control and colitis induced colon tissue. The results of the present study shows that the integrated pipeline can efficiently identify increased number of proteins compared to the conventional method which can be a breakthrough in identification of a potential biomarker candidate.

• 한국결정학회:학술대회논문집
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• 한국결정학회 2002년도 정기총회 및 추계학술연구발표회
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• pp.19-19
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• 2002

Perovskite-type titanate dielectrics have attracted much attention in memory devices such as DRAMs or FeRAMs due to their high dielectric constants. However, low volatility of the Ba, Sr, Pb or Zr precursors with only thd ligands has limitations in obtaining high quality thin films by liquid source metal organic chemical vapor deposition (LS-MOCVD) processes. To improve the volatility of these precursors, many attempts have been made such as adding polyether ligands to satisfy the coordinative saturation. We report the synthesis of new precursors Ba(thd)₂(tmeea) and Sr(thd)₂(tmeea), where tmeea = tris[2-(2-methoxyethoxy)ethyl]amino, and LS-MOCVD of barium strontium titanate (BSTO) thin films using these precursors. Due to increased basicity of amines compared with ethers, it is expected that the nitrogen-donor ligand will make a strong bond to a metal than an analogous oxygen-donor ligand, consequently improving the volatility and thermal behavior of these precursors. Thin films of BSTO were grown on Pt(111)/SiO₂/Si(100) substrates by LS-MOCVD using a cocktail source consisting of the conventional Ti precursor Ti(thd)₂(O/sup i/Pr), and these new Ba and Sr precursors. As-grown films were characterized by XPS, SEM, XRD, XRF, and C-V and I-V measurements. BSTO films grown at 420℃ were stoichiometric barium strontium titanate with very smooth surface morphology and their dielectric constants were found to be as targe as 450. Dependence of the composition, microstructure and the electrical properties of the BSTO films on the growth temperature, annealing temperature, working pressure, and the composition of the cocktail source will be discussed.

• Bulletin of the Korean Chemical Society
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• 제30권2호
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• pp.348-354
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• 2009

Copper(II) complexes with tetraoxo dithia tetraaza macrocyclic ligands; [18]ane$N_4S_2$: 1,4,10,13-tetraaza-5,9,14,18-tetraoxo-7,16-dithia-cyclooctadecane, [20]ane$N_4S_2$: 1,5,11,15-tetraaza-6,10,16,20-tetraoxo-8,18-dithia-cyclocosane,Bzo2[18]ane$N_4S_2$: dibenzo-1,4,10,13-tetraaza-5,9,14,18-tetraoxo-7,16-dithia-cyclooctadecane, Bzo2[20]ane$N_4S_2$: dibenzo-1,5,11,15-tetraaza-6,10,16,20-tetraoxo-8,18-dithia-cyclocosane; were entrapped in the nanopores of zeolite-Y by a two-step process in the liquid phase: (i) adsorption of [bis(diamine)copper(II)] (diamine = 1,2-diaminoethane, 1,3-diaminopropane, 1,2-diaminobenzene, 1,3-diaminobenzene); $[Cu(N-N)_2]^{2+}$-NaY; in the nanopores of the zeolite, and (ii) in situ template condensation of the copper(II) precursor complex with thiodiglycolic acid. The obtained complexes and new host-guest nanocomposite materials; $[Cu([18]aneN_4S_2)]^{2+}-NaY,\;[Cu([20]aneN_4S_2)]^{2+}-NaY,\;[Cu(Bzo_2[18]aneN_4S_2)]^{2+}-NaY,\;[Cu(Bzo_2[20]aneN_4S_2)]^{2+}$-NaY; have been characterized by elemental analysis FT-IR, DRS and UV-Vis spectroscopic techniques, molar conductance and magnetic moment data, XRD and, as well as nitrogen adsorption. Analysis of data indicates all of the complexes have been encapsulated within nanopore of zeolite Y without affecting the zeolite framework structure.

• Journal of Microbiology and Biotechnology
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• 제22권12호
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• pp.1653-1658
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• 2012

We have reported previously that a recombinant Escherichia coli co-expresses aminolevulinic acid (ALA) synthase, an NADP-dependent malic enzyme, and a dicarboxylate transporter-produced heme, an iron-chelated porphyrin, in a succinate-containing complex medium. To develop an industrially plausible process, a chemically defined medium was formulated based on M9 minimal medium. Heme synthesis was enhanced by adding sodium bicarbonate, which strengthened the C4 metabolism required for the precursor metabolite, although a pH change discouraged cell growth. Increasing the medium pH buffering capacity (100mM phosphate buffer) and adding sodium bicarbonate enabled the recombinant E. coli to produce heme at rates 60% greater than those in M9 minimal medium. Adding growth factors (1 mg/l thiamin, 0.01 mg/l biotin, 5 mg/l nicotinic acid, 1 mg/l pantothenic acid, and 1.4 mg/l cobalamin) also induced positive heme production effects at levels twice of heme production in M9-based medium. Porphyrin derivatives and heme were found in the chemically defined medium, and their presence was confirmed by liquid chromatography/mass spectroscopy (LC/MS). The formulated medium allowed for the production of $0.6{\mu}M$ heme, $29{\mu}M$ ALA, $0.07{\mu}M$ coproporphyrin I, $0.21{\mu}M$ coproporphyrin III, and $0.23{\mu}M$ uroporphyrin in a 3 L pH-controlled culture.