• Title/Summary/Keyword: Synthesis process

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Synthesis of Hydroxyapatite as the Artificial Bone Materials from Phosphate Wastewater Simulating Human Body Fluid (체액 모사 인산폐수로부터 인공뼈 재료로서의 수산아파타이트 합성에 관한 연구)

  • 이진숙;김동수
    • Resources Recycling
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    • v.13 no.3
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    • pp.3-11
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    • 2004
  • Basic studies have been conducted regarding the crystal formation of hydroxyapatite which was produced in the treatment process of phosphate-containing wastewater using calcium ions as the precipitating agent for its employment as the material for artificial bones. The precipitation of hydroxyapatite were conducted in the synthetic solution which simulating human body fluid for its increased applicability. Ca($NO_3$)$_2$$.$$4H_2$O and ($NH_4$)$_2$$HPO_4$ were employed for the precipitation of hydroxyapatite and its composition was analyzed after drying at 80oC. The thermal behavior of precipitate was investigated by examining the change in its crystalline structure according to the sintering temperature. DTA/TG analysis showed that the escape of moisture from the precipitate occurred at ca. $100^{\circ}C$ and the decomposition of ammonia and the evaporation of lattice water were brought about at around $250^{\circ}C$. X-ray diffraction analysis indicated that the thermally treated precipitate consisted mainly of hydroxyapatite. For dried precipitate, the bonds in the component materials which used for the precipitate formation were observed by FT-IR, and after thermal treatment the major bonds in the precipitate were shown to be $OH^{-}$, $PO_4^{3-}$ , and $CO_3^{ 2-}$ , which were main comprising bonds of hydroxyapatite.

Characterization of Embryo-specific Autophagy during Preimplantation (착상전 난자 자식작용의 특성규명)

  • Lee, Jae-Dal
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.8
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    • pp.3541-3546
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    • 2011
  • Autophagy is an evolutionarily conserved lysosomal pathway for degrading cytoplasmic proteins, macromolecules, and organelles in addition to recycling protein and ATP synthesis. Although autophagy is very important during embryogenesis, the mechanism underlying the dynamic development during this process remains largely unknown. In order to obtain insights into autophagy in early embryo development, we analyzed gene expression levels of autophagy-related genes (ATGs) in mouse embryos developing in vitro. Using real time RT-PCR technique, ATGs including Atg2a, Atg3, Atg4b, Atg5, Atg6, Atg7, Atg9a, and Wipi3, as maternal transcripts, were only up-regulated in 1-cell embryo stage before zygotic genomic activation (ZGA), and then expression decreased from 2-cell to blastocyst embryo stage. ATGs including Dram and Atg9b were expressed abundantly in 1-cell embryo state and in blastocyst embryo stage, athough Atg8 and Ulk1 were constantly expressed during preimplantation stage. However, Atg4d were only up-expressed from 4-cell to blastocyst stage. These results suggest that autophagy is related in mouse embryo, which possibly gives an important role for early development.

A Protective Effect of Chlorella Supplementation on Cadmium-induced Nephrotoxicity in the Rats

  • Hwang Yoo-Kyeong;Choi Hyun-Jin;Nan Meng;Yoo Jai-Du;Kim Yong-Ho
    • Biomedical Science Letters
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    • v.12 no.1
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    • pp.29-33
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    • 2006
  • The uptake of cadmium in animals is mainly accumulated in and affected to the liver and kidney by binding with red blood cells and serum albumin. The process accounts for more than 50% of the total accumulated cadmium in the body. The kidneys may be damaged without regarding the pathway uptake of cadmium. In a group of rats on supplements of 1% chlorella and 40 ppm cadmium, the concentration of cadmium in urine greatly decreased by 66% compared to control group, and the total synthesis of metallothionein decreased by 48.6% compared to control group. However, no previous study has assessed the protective effect on kidney damage induced by cadmium uptake through supplementation with chlorella. This study analyzed the biochemical marker for kidney damage in the rats after uptake of 40 ppm $CdCl_2$ and supplementation of the diet of Sprague Dawley (SD) rats with 1%, 5%, and 10% chlorella during 4 weeks. In a group of SD rats on supplementation with 1% chlorella and uptake of 40 ppm $CdCl_2,\;\beta_2$ microglobulin in the urine was found to be $3.1\pm0.6\;{\mu}g/L$, a decrease of 58% compared to a group of Sp rats on uptake of $CdCl_2$ only, in which the $\beta_2$ microglobulin was found to be $4.9\pm0.7\;{\mu}g/L$. According to the results of histopathological observation, the accumulation of mild and localized chronic inflammatory cells in kidney tissues was observed in 50% of the SD rats on uptake of cadmium only. In contrast, only 30% of the SD rats on supplementation with 1% chlorella and uptake of 40ppm $CdCl_2$, representing a histopathological abnormality, and there were no histopathological abnormalities at all in groups of SD rats on supplementation with 5% or 10% chlorella and uptake of 40 ppm $CdCl_2$. In conclusion, protein, calcium, and iron, which account for more than 50% of the total dried chlorella composition, may contribute to the reduction nephrotoxicity by stimulating both inhibited absorption of cadium and increased excretion of accumulated cadmium in kidneys.

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Luminescent Lanthanide Complexes for Advanced Photonics Applications

  • Eom, Yu Kyung;Ryu, Jung Ho;Kim, Hwan Kyu
    • Rapid Communication in Photoscience
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    • v.1 no.1
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    • pp.1-9
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    • 2012
  • Luminescent lanthanide complexes have been overviewed for advanced photonics applications. Lanthanide(III) ions ($Ln^{3+}$) were encapsulated by the luminescent ligands such as metalloporphyrins, naphthalenes, anthracene, push-pull diketone derivatives and boron dipyrromethene(bodipy). The energy levels of the luminescent ligands were tailored to maintain the effective energy transfer process from luminescent ligands to $Ln^{3+}$ ions for getting a higher optical amplification gain. Also, key parameters for emission enhancement and efficient energy transfer pathways for the sensitization of $Ln^{3+}$ ions by luminescent ligands were investigated. Furthermore, to enhance the optophysical properties of novel luminescent $Ln^{3+}$ complexes, aryl ether-functionalized dendrons as photon antennas have been incorporated into luminescent $Ln^{3+}$ complexes, yielding novel $Ln^{3+}$-cored dendrimer complex such as metalloporphyrins, naphthalenes, and anthracenes bearing the Fr$\acute{e}$chet aryl-ether dendrons, namely, ($Er^{3+}-[Gn-Pt-Por]_3$ (terpy), $Er^{3+}-[Gn-Naph]_3$(terpy) and $Er^{3+}-[Gn-An]_3$(terpy)). These complexs showed much stronger near-IR emission bands at 1530 nm, originated from the 4f-4f electronic transition of the first excited state ($^4I_{13/2}$) to the ground state ($^4I_{15/2}$) of the partially filled 4f shell. A significant decrease in the fluorescence of metalloporphyrins, naphthalenes and anthracene ligand were accompanied by a strong increase in the near IR emission of the $Ln^{3+}$ ions. The near IR emission intensities of $Ln^{3+}$ ions in the lanthanide(III)-encapsulated dendrimer complexes were dramatically enhanced with increasing the generation number (n) of dendrons, due to the site-isolation and the light-harvesting(LH) effects. Furthermore, it was first attempted to distinguish between the site-isolation and the light-harvesting effects in the present complexes. In this review, synthesis and photophysical studies of inert and stable luminescent $Ln^{3+}$ complexes will be dealt for the advanced photonics applications. Also, the review will include the exploratory investigation of the key parameters for emission enhancement and the effective energy transfer pathways from luminescent ligands to $Ln^{3+}$ ions with $Ln^{3+}$-chelated prototype complexes.

Cathode Characteristics in the Synthesis of $(La,\;Sr)MnO_{3+{\delta}$ of Precursor ($(La,\;Sr)MnO_{3+{\delta}$ 합성에 있어서 출발물질에 따른 양극특성)

  • Lee, Mi-Jai;Kim, Sei-Ki;Ji, Mi-Jung;Choi, Byung-Hyun;Park, Sang-Sun
    • 한국신재생에너지학회:학술대회논문집
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    • 2006.11a
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    • pp.360-363
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    • 2006
  • We synthesized $(La,\;Sr)MnO_{3+{\delta}$ as a cathode for SOFC by glycine nitrate process(GNP) and knew the different properties of $(La_{1-x}Sr_x)MnO_3$ by using nitrate solution and oxide solution as starting material. In case of using nitrate solution as a starting material, main crystal phase peak of $LaMnO_3$ increased as Sr content added up and a peak of $Sr_2MnO_4\;and\;La_2O_3$ was showed as a secondary phase. We added Mn excess to control a crystal phase. In this case, the electrical conductivity had a high value 210.3S/cm at $700^{\circ}C$ On the other side, when we used oxide solution as a starting material, we found main crystal phase of $LnMnO_3$ to increase as Sr content added up and a peak of $La_2O_3$ as a secondary phase. Similary, we added Mn excess to control a crystal phase in this case. We knew $(La,\;Sr)MnO_3$ powder to sinter well and the electrical conductivity of the sintered body at $1200^{\circ}C$ for 4hrs was 152.7s/cm at $700^{\circ}C$. The sintered $(La,\;Sr)MnO_3$ powder at $1000^{\circ}C$ for 4hrs got the deoxidization peak, depending on the temperature md in case of using nitrate solution as a start ing material the deoxidization peak was showed at $450^{\circ}C$ which is lower than used a oxide solution as a starting material. As a result, when $(La,\;Sr)MnO_3$ powder was synthesized to add Mn excess and to use nitrate solution as a starting material, we found it to have the higher deoxidization property and considered it as a cathode for m properly. And we found it to have different electrical conduct ivity the synthesized $(La,\;Sr)MnO_3$ powder by using different start ing materials like nitrate solution and oxide solution which influence a sintering density and crystal phase.

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Evaluation of the Wound-healing Activity of Rice Cell Extracts in Vitro (In vitro 실험을 통한 벼세포 추출물의 창상 치유 효능 평가)

  • Kim, Z-Hun;Kim, Sun-Mi;Park, Jin Ho;Park, Chan-Mi;Choi, Hong-Yeol;Lee, Hoomin;Park, Jae Kweon;Kwon, Soonjo;Kim, Dong-Il;Chang, Kyu-Ho;Choi, Yong-Soo;Lim, Sang-Min
    • Microbiology and Biotechnology Letters
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    • v.44 no.3
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    • pp.285-292
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    • 2016
  • In the present study, we evaluated the in vitro wound-healing properties of two types of rice cell extracts (RCEs; prepared using ethanol and pressurized hot water extraction methods), using human dermal fibroblasts and keratinocytes. The effects of the RCEs (at 25–100 μg/ml) on cytotoxicity and cell migration were assessed. Both RCEs were not cytotoxic to the two cell types, instead increasing their proliferation by up to 25% in a dose-dependent manner compared with the controls. Furthermore, both RCEs significantly enhanced the migratory ability of the two cell types (fibroblast, 230–450%; keratinocyte, 170–350%). Additionally, we examined the effect of the RCEs on type I collagen synthesis, which is important in the wound reconstruction process. The RCEs significantly increased collagen type I mRNA and protein levels to a degree comparable to that induced by vitamin C. These results suggest the RCEs to be candidate materials for use in promoting wound healing, through their actions of increasing cell migration and accelerating wound re-epithelialization.

The Effect of Reaction Temperature for Synthesis of LiMn2O4 by Calcination Process and the Electrochemical Characteristics (소성법에 의한 LiMn2O4의 제조시 반응 온도의 영향과 전기화학적 특성)

  • Lee, Chul-Tae;Lee, Jin-Sik;Kim, Hyun-Joong
    • Applied Chemistry for Engineering
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    • v.9 no.2
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    • pp.220-225
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    • 1998
  • The spinel structured $LiMn_2O_4$ was prepared from $Li_2CO_3$ and $MnO_2$ by calcination at various temperatures in the range of $750{\sim}900^{\circ}C$. It was found that the most suitable cubic structure of $LiMn_2O_4$ was obtained by heating at $850^{\circ}C$ for 12 hrs. However, in the calcination at $900^{\circ}C$, $Mn^{4+}$ of 0.06M was changed to $Mn^{+3}$ by the oxygen loss, so that it has been shown that the formula has changed to $LiMn_2O_{3.97}$. This phenomena were in agreement with the Jahn-Teller distortion by the increment of $Mn^{+3}$ ion on the octahedral sites of the spinel structured $LiMn_2O_4$. The results showed that after 15 charge/discharge cycles in the voltage range from 3.5V to 4.3V versus Li/$Li^+$ with a current density of $0.25mA/cm^2$, the spinel structured $LiMn_2O_4$ that was prepared at $900^{\circ}C$ showed a lower discharge capacity, 82~50 mAh/g, while the $LiMn_2O_4$, prepared at $850^{\circ}C$, showed the discharge capacity of 102~64 mAh/g.

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The Influence of Oxygen Gas Flow Rate on Growth of Tin Dioxide Nanostructures (이산화주석 나노구조물의 성장에서 산소가스 유량이 미치는 영향)

  • Kim, Jong-Il;Kim, Ki-Chul
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.10
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    • pp.1-7
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    • 2018
  • Tin dioxide, $SnO_2$, is applied as an anode material in Li-ion batteries and a gas sensing materials, which shows changes in resistance in the presence of gas molecules, such as $H_2$, NO, $NO_2$ etc. Considerable research has been done on the synthesis of $SnO_2$ nanostructures. Nanomaterials exhibit a high surface to volume ratio, which means it has an advantage in sensing gas molecules and improving the specific capacity of Li-ion batteries. In this study, $SnO_2$ nanostructures were grown on a Si substrate using a thermal CVD process with the vapor transport method. The carrier gas was mixed with high purity Ar gas and oxygen gas. The crystalline phase of the as-grown tin oxide nanostructures was affected by the oxygen gas flow rate. The crystallographic property of the as-grown tin oxide nanostructures were investigated by Raman spectroscopy and XRD. The morphology of the as-grown tin oxide nanostructures was confirmed by scanning electron microscopy. As a result, the $SnO_2$ nanostructures were grown directly on Si wafers with moderate thickness and a nanodot surface morphology for a carrier gas mixture ratio of Ar gas 1000 SCCM : $O_2$ gas 10 SCCM.

A Study on the high-speed Display of Radar System Positive Afterimage using FPGA and Dual port SRAM (FPGA와 Dual Port SRAM 적용한 Radar System Positive Afterimage 고속 정보 표출에 관한 연구)

  • Shin, Hyun Jong;Yu, Hyeung Keun
    • Journal of Satellite, Information and Communications
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    • v.11 no.4
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    • pp.1-9
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    • 2016
  • This paper was studied in two ways with respect to the information received from the video signal separation technique of PPI Scop radar device. The proposed technique consists in generating an image signal through the video signal separation and synthesis, symbol generation, the residual image signal generation process. This technology can greatly improve the operating convenience with improved ease of discrimination, screen readability for the operator in analyzing radar information. The first proposed method was constructed for high-speed FPGA-based information processing systems for high speed operation stability of the system. The second proposed method was implemented intelligent algorithms and a software algorithm function curve associated resources.This was required to meet the constraints on the radar information, analysis system. Existing radar systems have not the frame data analysis unit image. However, this study was designed to image data stored in the frame-by-frame analysis of radar images with express information MPEG4 video. Key research content is to highlight the key observations expresses the target, the object-specific monitoring information to the positive image processing algorithm and the function curve delays. For high-definition video, high-speed to implement data analysis and expressing a variety of information was applied to the ARM Processor Support in Pro ASIC3.

A Study on Synthesis and Magnetic Properties of Soft Magnetic Materials Sintered at Low Temperature (저온 소결용 연자성 물질의 합성 및 자기적 특성 연구)

  • Koh Jae Gu
    • Resources Recycling
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    • v.12 no.6
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    • pp.13-18
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    • 2003
  • The initial NiCuZn synthetic ferrite were acquired from thermally decomposing the metal nitrates Fe($NO_3$)$_3$$9H_2$O, Zn($NO_3$)$_2$$6H_2$O, Ni($NO_3$3)$_2$$6H_2$O and Cu(NO$_3$)$_2$$3H_2$O at 1$50^{\circ}C$ for 24 hours and was calcined at $500^{\circ}C$. Each of those was pulverized for 3 and 9 hours in a steel ball mill and was sintered between $700^{\circ}C$ and $1,000^{\circ}C$ for 1 hour, and then their microstructures and magnetic properties were examined. We could make the initial specimens chemically bonded in liquid at the temperature as low as $150 ^{\circ}C$, by using the melting points less than $ 200^{\circ}C$ of the metal nitrates instead of the mechanical ball milling, then narrowed a distance between the particles into a molecular level, and thus lowed sintering temperature by at least $200 ^{\circ}C$ to $300^{\circ}C$ Their initial permeability was 50 to 490 and their saturation magnetic induction density and coercive force 2,400G and 0.3 Oe to 1.2 Oe each, which were similar to those of NiCuZn ferrite synthesized in the conventional process.