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Simultaneous Concentration and Determination of Several Trace Elements in Sea Water by Ce(OH)3 Coprecipitation (Ce(OH)3의 공침부선에 의한 해주중 몇 가지 미량원소의 동시 농축 및 정량)

  • Woo-Sik Sung;Hee-Seon Choi;Young-Sang Kim
    • Journal of the Korean Chemical Society
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    • v.37 no.3
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    • pp.327-333
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    • 1993
  • A method was developed for the determination of trace elements in seawater by precipitate flotation preconcentration and subsequent flame atomic absorption detection. In order to quantitatively coprecipitate trace ions such as Cd(II), CuI(II), Fe(III), Mn(II), Pb(II) and Pd(II), 2.0 ml of 1.0M cerium(III) solution was added to 1.0l of seawater and the pH was adjusted to 9.5 with 5.0 M sodium hydroxide solution while stirring with a magnetic stirrer. The precipitate was floated with the aid of surfactant solution (1.0 ml of 0.3% sodium oleate) by bubbling nitrogen gas through a porous (No. 4) fritted glass disk. The floats was collected in a small Erlenmeyer flask by suction. The washed precipitate was dissolved in 8.0 M nitric acid and marked with deionized water in the volumetric flask of 10.0 ml. The analyte was determined by measuring the atomic absorbances in 100-fold concentrated solution. Above all analytes in Kangnung (East Sea) and Kanghwado (West Sea) sea waters were found to be under the detection limit of this method. The recoveries of over 92% for all analytes spiked into seawater samples showed that this method was applicable to the analysis of real seawater.

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Activation of Phospholipase Cγ by Nitric Oxide in Choriocarcinoma Cell Line, BeWo Cells (Choriocarcinoma 세포주 BeWo 세포에서 nitric oxide에 의한 phospholipase Cγ 의 활성)

  • 차문석;곽종영
    • Journal of Life Science
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    • v.13 no.6
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    • pp.849-855
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    • 2003
  • Nitric oxide (NO) plays an important role as a signaling molecule in the proliferation of placenta trophoblasts. In this study, we investigated the effect of NO on the activation of phospholipase C (PLC) in BeWo cells, choriocar-cinoma cell line. Sodium nitroprusside (SNP), an agent to produce NO spontaneously in cells, alone increased 3H thymidine incorporation of BeWo cells, indicating NO stimulates proliferation of the cells. NO-induced proliferation of BeWo cells was blocked by U73122, an inhibitor of PLC, suggesting that NO-induced PLC activation is involved in the cell proliferation. NO also stimulated extracellular signal-regulated kinase (ERK) in BeWo cells, indicated by increased phosphorylation of ERK1/2 in Western blotting using anti-phospho-ERK1/2 antibody. NO-induced phos-phorylation of ERK1/2 was not abrogated by U73122. PLCγ1l but notPLCγ2 was tyrosine phosphorylated by SNP in immunoprecipitation assay using anti-PLCγ1/PLCγ2 antibodies, and SNP-induced phosphorylation of PLCγ1 was abrogated by pre-treatment of cells with genistein and PD98059, indicating that NO induced-phosphorylation of PLCγ1 is mediated by ERK. These results suggest that NO stimulates the proliferation of BeWo cells through ERK and PLCγ1.

Synthesis of Dendritic Polystyrene-block-Linear Poly(t-butyl acrylate) Copolymers by an Amide Coupling (아미드 커플링을 통한 덴드리틱 Polystyrene-Block-Linear Poly(t-butyl acrylate) 공중합체의 합성)

  • Song, Jie;Cho, Byoung-Ki
    • Polymer(Korea)
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    • v.33 no.2
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    • pp.158-163
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    • 2009
  • In this study, we synthesized a series of dendritic polystyrene-b-linear poly (t-butyl acrylate) copolymers with well-defined molecular architectures. The hydroxyl group located at the focal point of the second generation dendron bearing polystyrene (Mn = 1000 g/mol) peripheries was converted into amine group via the following stepwise reactions: 1) tosylatoin, 2) azidation, and 3) reduction. On the other hand, the linear poly (t-butyl acrylate)s were prepared by an atom transfer radical polymerization (ATRP) of t-butyl acrylate where benzyl 2-bromopropanoate and Cu(I)Br/PMDETA were used as initiator and catalyst, respectively. To convert the end group of prepared poly (t-butyl acrylate) s into carboxylic acid, a debenzylation was performed using Pd/C catalyst under H2 atmosphere. In the final step, dendritic-linear block copolymers were obtained through a simple amide coupling reaction mediated by 4-(dimethylamino) pyridine(DMAP) and N,N'-diisopropylcarbodiimide(DIPC). The resulting diblock copolymers were shown to have well-defined molecular weights and narrow molecular weight distributions as supported by 1H-NMR spectroscopy and gel permeation chromatography(GPC).

Light Scattering-enhanced Upconversion Efficiency in Silica Microparticles-embedded Polymeric Thin Film (고분자 박막 내에 담지 된 실리카 마이크로입자의 광산란 효과에 의한 광에너지 상향전환 효율 향상)

  • Choe, Hyun-Seok;Lee, Hak-Lae;Lee, Myung-Soo;Park, Jeong-Min;Kim, Jae-Hyuk
    • Applied Chemistry for Engineering
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    • v.30 no.1
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    • pp.88-94
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    • 2019
  • Triplet-triplet annihilation upconversion (TTA-UC) is a photochemical process wherein two or more low-energy photons are converted to a high-energy photon through a special energy transfer mechanism. Herein, we report a strategy to enhance the efficiency of TTA-UC through the light-scattering effect induced by silica microparticles (SM) embedded in polymeric thin films. By incorporating monodisperse uniform silica microparticles with a uniform size of 950 nm synthesized by St¨ober-based seeded growth method into UC polymeric thin films, the UC intensity in the 430-570 nm range was enhanced by as much as 64% when irradiated by 635 nm laser. Analyzing the lifetime of PdTPBP phosphorescence revealed that the presence of SM in the UC layer does not affect triplet-triplet energy transfer (TTET) between sensitizers and acceptors, supporting the enhancement of TTA-UC originated from the light-scattering effect. On the other hand, the incorporation of SM in UC layer is shown to enhance the triplet-triplet annihilation (TTA) efficiency, which results in a 1.5-fold increase of the ΦUC, by scattering light source and thus increasing the number of excited photons to be utilized in TTA-UC process.

Effect of Various Factors on Early THP-1 Cell Adhesion Induced Phorbol 12-Myristate 13-Acetate (PMA) (Phorbol 12-myristate 13-acetate (PMA) 처리로 유도되는 THP-1 세포의 초기 부착에 관한 다양한 인자의 효과)

  • Jo, Yong-Sam;Shin, Ji-Hyun;Choi, Tae-Saeng
    • Journal of Life Science
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    • v.18 no.7
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    • pp.952-957
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    • 2008
  • We evaluated the effects of various factors (e.g., serum, inhibitors of protein synthesis, and cytoskeleton and protein kinases) on early PMA-induced THP-1 cell adhesion using an adhesion assay with Sulforhodamine B (SRB) staining, which was used to assess the proliferation of the attached cells. THP-1 cell adhesion to a plastic substrate was detected 1 hr after exposure to Phorbol 12-Myristate 13-Acetate (PMA) and peaked after 18 hr. At concentrations > 25 nM PMA, the level of adhesion did not change. Based on our preliminary results, we used 25 nM PMA and 5 hr of culture as standard assay conditions. Early PMA-induced cell adhesion was not affected by the presence of serum or PD 98059 in the culture medium, but was affected by the addition of PKC inhibitors and cycloheximide. In the presence of actin inhibitor with PMA, the cell adhesion increased when comparing with PMA treatment only. Thus, early PMA-induced adhesion of THP-1 cells does not require serum in the culture medium, MAP-kinase activation, or actin polymerization, but does require de novo protein synthesis and PKC activation. Our SRB-based cell adhesion assay may be used to screen other PKC inhibitors.

Production of Ethylbenzene from 4-Vinylcyclohexene (4-비닐시클로헥센을 이용한 에틸벤젠의 제조)

  • Joo, Young J.;Won, Jeong-Im;Kim, Chang-Min;Park, Kwang-Chun;Lee, Sang-Ok;Kim, Hong-Seok
    • Applied Chemistry for Engineering
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    • v.7 no.2
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    • pp.326-333
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    • 1996
  • Dehydrogenation of 4-vinylcyclohexene(4-VCH) to ethylbenzene is elucidated via catalytic transfer hydrogenation with the heterogeneous catalyst of Pd/C. Hydrogen-donor solvent is ethanol or water. Oxidizers of the catalytic dehydrogenation reaction are mono- or dinitro compounds, H2O2, NaClOn (n=1~4), or oxygen at 70110C. The ratio of 4-VCH/Nitro compounds is 1:0.02 to 1:0.5 and 4-VCH vs. H2O2 or NaClOn (n=1~4) is 1:0.1 to 1:3.

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EFFECTS OF ALLOYING ELEMENTS ON VARIOUS PROPERTIES OF DENTAL SILVER-PALLADIUM ALLOYS (치과용(齒科用) 은(銀)-파라디움합금(合金)의 합금원소(合金元素)가 제성질(諸性質)에 미치는 영향(影響)에 관(關)한 연구(硏究))

  • Kim, Chun-Jin;Park, Nam-Soo
    • The Journal of Korean Academy of Prosthodontics
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    • v.22 no.1
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    • pp.95-108
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    • 1984
  • Even though the tarnishing and corrosion problems characteristic with dental silver-palladium alloy are not yet fully solved, it is recently widely used because of its low cost. However the effects of major alloying elements on the various properties of this system are not fully understood. The object of this research is to clarify the effects of In and Zn additives on the corrosion and tarnishing resistances and precipitation hardening behavior of this sytem, using electrodynamic polarization, immersion, and Vicker's microhardness test and X-ray diffraction and electron probe micro analysis methods. The obtained results were as follows: I. As indium content is increased, both the corrosion resistance in Cl-solution and microhardness are also increased while the tarnishing resistance is decreased. 2. As Zinc content is increased, the corrosion resistance is decreased, but tarnishing resistance is increased 3. At 70Ag-25Pd-2.5Zn-2.5In composition, the precipitation harding behavior was mot significant. The optimum aging temperature was 450C and the time was 2 hrs. The resulting specimen of this work carried 180VHN. 4. Under the heat treatment, the changes in the mechanical property are due to the changes in the shape and composition of dendrite matrix, namely, it is because of the precipitation hardening behavior which has been proved by electron probe micro analysis and optical microscopic finding.

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A Study on the Hydrogenation of CO2 Using Cu/ZnO/Cr2O3/Al2O3 Catalysts (Cu/ZnO/Cr2O3/Al2O3 촉매를 이용한 이산화탄소의 수소화 연구)

  • Sim, Kyu-Sung;Han, Sang-Do;Kim, Jong-Won;Kim, Youn-Soon;Myoung, Kwang-Sik;Park, Ki Bae
    • Journal of Hydrogen and New Energy
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    • v.7 no.2
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    • pp.147-155
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    • 1996
  • The aim of this study is the development of technologies of methanol production from carbon dioxide by catalytic hydrogenation. Experiments about carbon dioxide hydrogenation by catalyst mixed with CuO, ZnO, Cr2O3 and Al2O3 were conducted to find optimum catalyst and reaction condition. Reactions were carried out at atmospheric and high pressures between 200 to 350C. High yield of methanol was obtained with Cu/ZnO/Cr2O/Cr2O3/Al2O3 catalyst at 250C and above 30 atmospheric pressure. There was not any increament of hydrogenation reactivity for the catalysts which was made by the addition of Pd to Cu/ZnO/Cr2O/Cr2O3/Al2O3.

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Effect of Nardostachys chinensis on Induction of Differentiation in U937 Monomyelocytic Cells (감송향(甘松香) 물추출물이 U937 백혈병 세포의 분화유도에 미치는 영향)

  • Kim, Jin-Kuk;Ju, Sung-Min;Jeon, Byung-Jae;Yang, Hyun-Mo;Jeon, Byung-Hun
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.25 no.1
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    • pp.29-36
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    • 2011
  • Nardostachyts chinensis (N. chinensis) belonging to the family Valerianaceae has been used to elicit stomachic and sedative effects. The MAPKs are serine/threonine kinases involved in the regulation of various cellular responses, such as cell proliferation, differentiation and apoptosis. The PKC also plays a key role in regulating the response of hematopoietic cells to both physiological and pathological inducers of proliferation and differentiation. This study investigated the signaling pathways on the U937 cell differentiation induced by N. chinensis. N. chinensis induced the differentiation of U937 cells, as shown by increased of differentiation surface antigen CD11b. Activation of ERK increased time-dependently in differentiation of U937 cells induced by N. chinensis, but activations of JNK and p38 were unaffected. Inhibitor of ERK (PD98059) significantly reduced CD11b expression induced by N. chinensis in U937 cells. In addition, N. chinensis increased protein level of PKC βI and PKC βII isoforms, but the protein level of PKC α and PKC γwas constant. PKC inhibitors (GF 109203X and H-7) inhibited U937 cell differentiation and the ERK activation induced by N. chinensis. These results indicated that PKC and ERK may be involved in U937 cell differentiation induced by N. chinensis.

Effect of Extraction Temperature and Time on Saponin Composition of Red Ginseng Extract (추출온도(抽出溫度) 및 시간(時間)이 홍삼(紅蔘)엑기스의 사포닌 조성(組成)에 미치는 영향)

  • Sung, Hyun-Soon;Yang, Cha-Bum;Kim, Woo-Jung
    • Korean Journal of Food Science and Technology
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    • v.17 no.4
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    • pp.265-270
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    • 1985
  • The saponin yield and its compositional changes of red ginseng extract (RG-EXT) was investigated during extraction at various temperature for 5 times of 8 hours. The higher temperature resulted an increase in solids yield while the total saponin recovered was decreased, particularly at 100C. A relatively lower thermal stability was found for protopanaxadiol saponin, one of the saponin fractions, than protopanaxatriol saponin. The compositional ratio of saponin at ginsenoside level was little affected by extraction time. The yields data showed that more than 94% of total saponin was recovered by 34 times of 8 hours extraction. Extraction at 80C for 4 times of 8 hours were suggested for preparation of RG-EXT from the result of this work.

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