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Sample records for temperature direct synthesis

  1. Synthesis and characterization of Cu-MFI catalyst for the direct medium temperature range NO decomposition

    Directory of Open Access Journals (Sweden)

    Valkaj Karolina Maduna

    2016-03-01

    Full Text Available In this study the physico-chemical and catalytic properties of copper bearing MFI zeolites (Cu-MFI with different Si/Al and Si/Cu ratios were investigated. Two different methods for incorporation of metal ions into the zeolite framework were used: the ion exchange from the solution of copper acetate and the direct hydrothermal synthesis. Direct synthesis of a zeolite in the presence of copper-phosphate complexes was expected to generate more active copper species necessary for the desired reaction than the conventional ion exchange method. Direct decomposition of NO was used as a model reaction, because this reaction still offers a very attractive approach to NOX removal. The catalytic properties of zeolite samples were studied using techniques, such as XRD, SEM, EPR and nitrogen adsorption/desorption measurements at 77 K. Results of the kinetic investigation revealed that both methods are applicable for the preparation of the catalysts with active sites capable of catalyzing the NO decomposition. It was found out that Cu-MFI zeolites obtained through direct synthesis are promising catalysts for NO decomposition, especially at lower reaction temperatures. The efficiency of the catalysts prepared by both methods is compared and discussed.

  2. Direct synthesis of large-area continuous ReS2 films on a flexible glass at low temperature

    Science.gov (United States)

    Kim, Youngchan; Kang, Byunggil; Choi, Yongsuk; Cho, Jeong Ho; Lee, Changgu

    2017-06-01

    Rhenium disulfide (ReS2) has been attracting attentions due to the direct bandgap regardless of the thickness and anisotropic electrical, mechanical and optical properties deriving from its unique crystal lattice structure. In order to utilize these properties, some synthesis methods of ReS2 have been studied for electronic applications. However, their results are not suitable for practical applications because of non-uniformity, discontinuity and difficulty of large-area continuous film growth. Here, we report the synthesis method of layer-controlled wafer-scale (7  ×  2 cm2) ReS2 films by chemical vapor deposition with high uniformity and continuity. Especially, we demonstrate successfully a direct synthesis of ReS2 on a transparent flexible glass substrate at low synthesis temperature (450 °C) without the aid of a catalyst or a plasma enhanced system. The field effect transistors with as-grown ReS2 films on the flexible glass exhibit typical n-type behavior with low threshold voltage of 0.75 V, high on-off ratio of ~105, low subthreshold swing of 260 mV/decade and mobility of 0.13 cm2 V-1 S-1. The direct synthesis of ReS2 films on flexible glass will provide the platform to realize large area transfer-free fabrication of high quality transparent flexible electronic devices.

  3. Direct synthesis of chromium perovskite oxyhydride with a high magnetic-transition temperature.

    Science.gov (United States)

    Tassel, Cédric; Goto, Yoshihiro; Kuno, Yoshinori; Hester, James; Green, Mark; Kobayashi, Yoji; Kageyama, Hiroshi

    2014-09-22

    We report a novel oxyhydride SrCrO2H directly synthesized by a high-pressure high-temperature method. Powder neutron and synchrotron X-ray diffraction revealed that this compound adopts the ideal cubic perovskite structure (Pm3̄m) with O(2-)/H(-) disorder. Surprisingly, despite the non-bonding nature between Cr 3d t(2g) orbitals and the H 1s orbital, it exhibits G-type spin ordering at T(N)≈380 K, which is higher than that of RCrO3 (R=rare earth) and any chromium oxides. The enhanced T(N) in SrCrO2H with four Cr-O-Cr bonds in comparison with RCr(3+)O3 with six Cr-O-Cr bonds is reasonably explained by the tolerance factor. The present result offers an effective strategy to tune octahedral tilting in perovskites and to improve physical and chemical properties through mixed anion chemistry. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. A novel method for direct fabrication of ferromolybdenum using molybdenite via self-propagation high temperature synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Golmakani, M.H.; Vahdati khaki, J., E-mail: vahdati@um.ac.ir; Babakhani, A.

    2017-06-15

    Direct production of ferromolybdenum from molybdenite (MoS{sub 2}), in the presence of lime as a desulfurizing reagent using combustion synthesis process is investigated. Thermodynamic calculations and measurement of the adiabatic temperature of the reaction denoted that the process is in agreement with the Merzhanov criterion for self-sustaining processes. The experimental results indicated a relatively complete separation between the molten metal droplets and the co-existing slag. The slag and metal phases were characterized by X-ray diffraction, electron microscopy and wet chemical analysis techniques. It was found that sulfur is mainly distributed into the slag in the form of solid calcium sulfide (CaS). The Lack of calcium oxide in the slag indicated a complete desulfurization reaction between lime and the sulfur in molybdenum sulfide. Characterization of the molted metal revealed that only two phases namely Fe{sub 3}Mo{sub 3}C and Fe{sub 3}Mo exist in the melt. Mass balance calculations showed an Iron-molybdenum recovery greater than 85%. Analyses of the phases indicated that a significant amount of Fe{sub 3}Mo{sub 3}C phase (60–70 wt%) is present in ferromolybdenum molten droplets even though the raw materials were low in carbon. Chemical analysis and microstructural studies of the raw materials and the products showed that carbon is not present in sufficient quantities to produce this amount of Fe{sub 3}Mo{sub 3}C; therefore the structure of this phase should contain a high concentration of carbon vacancies. The deviation of Fe{sub 3}Mo{sub 3}C{sub 1-x} peaks in X-ray diffraction pattern compared to its standard reference peaks and a calculated 0.02% decrease in the lattice parameter of this phase are evidence of the presence of these carbon vacancies. - Highlights: • A new SHS method for direct fabrication of ferromolybdenum from MoS{sub 2} is introduced. • Addition of CaO as an effective desulfurizing agent has been investigated. • Removing the

  5. Direct synthesis of multi-layer graphene film on various substrates by microwave plasma at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hyun Jae [Plasma Technology Research Center, 814-2 Osickdo-dong (SGFEZ), Gunsan, Jeollabuk-do 573-540 (Korea, Republic of); Ahn, Byung Wook; Kim, Tae Yoo; Lee, Jung Woo [School of Advanced Materials Science and Engineering, Advanced Materials and Process Research Center (AMPRC), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Jung, Yong Ho; Choi, Yong Sup [Plasma Technology Research Center, 814-2 Osickdo-dong (SGFEZ), Gunsan, Jeollabuk-do 573-540 (Korea, Republic of); Song, Young Il, E-mail: physein01@skku.edu [School of Advanced Materials Science and Engineering, Advanced Materials and Process Research Center (AMPRC), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Suh, Su Jeong, E-mail: suhsj@skku.edu [School of Advanced Materials Science and Engineering, Advanced Materials and Process Research Center (AMPRC), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2015-07-31

    We introduce a possible route for vertically standing multi-layer graphene films (VMGs) on various substrates at low temperature by electron cyclone resonance microwave plasma. VMG films on various substrates, including copper sheet, glass and silicon oxide wafer, were analyzed by studying their structural, electrical, and optical properties. The density and temperature of plasma were measured using Cylindrical Langmuir probe analysis. The morphologies and microstructures of multi-layer graphene were characterized using field emission scattering electron microscope, high resolution transmission electron microscope, and Raman spectra measurement. The VMGs on different substrates at the same experimental conditions synthesized the wrinkled VMGs with different heights. In addition, the transmittance and electrical resistance were measured using ultra-violet visible near-infrared spectroscopy and 4 probe point surface resistance measurement. The VMGs on glass substrate obtained a transmittance of 68.8% and sheet resistance of 796 Ω/square, whereas the VMGs on SiO{sub 2} wafer substrate showed good sheet resistance of 395 Ω/square and 278 Ω/square. The results presented herein demonstrate a simple method of synthesizing of VMGs on various substrates at low temperature for mass production, in which the VMGs can be used in a wide range of application fields for energy storage, catalysis, and field emission due to their unique orientation. - Highlights: • We present for synthesis method of graphene at low temperature on various substrates. • We grow the graphene films at low temperature under of 432 °C. • Structural information of graphene films were studied upon Raman spectroscopy. • Inter-layer spacing of vertically standing graphene relies on synthesis time. • We measured a transmittance and a resistance for graphene films on difference substrate.

  6. Direct Synthesis of Dimethyl Carbonate from Carbon Dioxide and Methanol at Room Temperature Using Imidazolium Hydrogen Carbonate Ionic Liquid as a Recyclable Catalyst and Dehydrant.

    Science.gov (United States)

    Zhao, Tianxiang; Hu, Xingbang; Wu, Dongsheng; Li, Rui; Yang, Guoqiang; Wu, Youting

    2017-05-09

    The direct synthesis of dimethyl carbonate (DMC) from CO2 and CH3 OH was achieved at room temperature with 74 % CH3 OH conversion in the presence of an imidazolium hydrogen carbonate ionic liquid ([Cn Cm Im][HCO3 ]). Experimental and theoretical results reveal that [Cn Cm Im][HCO3 ] can transform quickly into a CO2 adduct, which serves as an effective catalyst and dehydrant. Its dehydration ability is reversible. The energy barrier of the rate-determining step for the DMC synthesis is only 21.7 kcal mol(-1) . The ionic liquid can be reused easily without a significant loss of its catalytic and dehydrating ability. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Direct Synthesis of Fe3C-Functionalized Graphene by High Temperature Autoclave Pyrolysis for Oxygen Reduction

    DEFF Research Database (Denmark)

    Hu, Yang; Jensen, Jens Oluf; Zhang, Wei

    2014-01-01

    We present a novel approach to direct fabrication of few-layer graphene sheets with encapsulated Fe3C nanoparticles from pyrolysis of volatile non-graphitic precursors without any substrate. This one-step autoclave approach is facile and potentially scalable for production. Tested as an electroca...

  8. Direct synthesis of Fe3 C-functionalized graphene by high temperature autoclave pyrolysis for oxygen reduction.

    Science.gov (United States)

    Hu, Yang; Jensen, Jens Oluf; Zhang, Wei; Huang, Yunjie; Cleemann, Lars N; Xing, Wei; Bjerrum, Niels J; Li, Qingfeng

    2014-08-01

    We present a novel approach to direct fabrication of few-layer graphene sheets with encapsulated Fe3 C nanoparticles from pyrolysis of volatile non-graphitic precursors without any substrate. This one-step autoclave approach is facile and potentially scalable for production. Tested as an electrocatalyst, the graphene-based composite exhibited excellent catalytic activity towards the oxygen reduction reaction in alkaline solution with an onset potential of ca. 1.05 V (vs. the reversible hydrogen electrode) and a half-wave potential of 0.83 V, which is comparable to the commercial Pt/C catalyst. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Direct Synthesis of Fluorinated Heteroarylether Bioisosteres

    Science.gov (United States)

    Zhou, Qianghui; Ruffoni, Alessandro; Gianatassio, Ryan; Fujiwara, Yuta; Sella, Eran; Shabat, Doron

    2013-01-01

    This work delineates a method for the modular synthesis of reagents that are capable of direct incorporation of difluoroalkyl groups onto heterocycles. The scope and generality of this method is exemplified with the difluoroethyl group (along with the introduction of a new reagent for difluoroethylation, DFES-Na) and a proof of principle is shown for a general synthesis of fluorinated heteroarylether bioisosteres. PMID:23460402

  10. Low temperature synthesis of porous silicate ceramics

    Directory of Open Access Journals (Sweden)

    Méndez Enríquez Y.

    2007-01-01

    Full Text Available Impregnation of a polyurethane sponge with kaolin, feldspar, silica, fusible glass slurry followed by temperature treatment in air in the temperature range 800-1000 0 C leads to the formation of aluminosilicate ceramics with a set pore size. The low-temperature synthesis of porous ceramics is based on the stage-by-stage formation of low-temperature eutectics and thermodestruction of polyurethane sponge.

  11. Direct hydrothermal synthesis of metal intercalated hexagonal ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 115; Issue 5-6. Direct hydrothermal synthesis of metal intercalated hexagonal molybdates, M x + Mo 6 − x / 3 O 18 − x (OH) x . y H2O (M = Li, Rb, Cs, NH4). S Upreti A Ramanan. Volume 115 Issue 5-6 October-December 2003 pp 411-417 ...

  12. Ammonia synthesis at low temperatures

    DEFF Research Database (Denmark)

    Rod, Thomas Holm; Logadottir, Ashildur; Nørskov, Jens Kehlet

    2000-01-01

    have been carried out to evaluate its feasibility. The calculations suggest that it might be possible to catalytically produce ammonia from molecular nitrogen at low temperatures and pressures, in particular if energy is fed into the process electrochemically. (C) 2000 American Institute of Physics....

  13. Manufacturing Demonstration Facility: Low Temperature Materials Synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Graham, David E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Moon, Ji-Won [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Armstrong, Beth L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Datskos, Panos G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Duty, Chad E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gresback, Ryan [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ivanov, Ilia N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jacobs, Christopher B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jellison, Gerald Earle [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jang, Gyoung Gug [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Joshi, Pooran C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jung, Hyunsung [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Meyer, III, Harry M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Phelps, Tommy [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-06-30

    The Manufacturing Demonstration Facility (MDF) low temperature materials synthesis project was established to demonstrate a scalable and sustainable process to produce nanoparticles (NPs) for advanced manufacturing. Previous methods to chemically synthesize NPs typically required expensive, high-purity inorganic chemical reagents, organic solvents and high temperatures. These processes were typically applied at small laboratory scales at yields sufficient for NP characterization, but insufficient to support roll-to-roll processing efforts or device fabrication. The new NanoFermentation processes described here operated at a low temperature (~60 C) in low-cost, aqueous media using bacteria that produce extracellular NPs with controlled size and elemental stoichiometry. Up-scaling activities successfully demonstrated high NP yields and quality in a 900-L pilot-scale reactor, establishing this NanoFermentation process as a competitive biomanufacturing strategy to produce NPs for advanced manufacturing of power electronics, solid-state lighting and sensors.

  14. High-pressure direct synthesis of aluminium nitride

    CERN Document Server

    Bockowski, M; Grzegory, I; Krukowski, S; Wróblewski, M; Porowski, S

    2002-01-01

    We report the results of direct synthesis of aluminium nitride (AlN) under high nitrogen pressure up to 1 GPa and temperatures up to 2000 K. At pressure from 10 to 650 MPa we observe the combustion synthesis of AlN. As the result of the combustion process one can obtain the AlN sintered powder or AlN/Al metal matrix composites. For N sub 2 pressure higher than 650 MPa the crystal growth of AlN from the solution of atomic nitrogen in aluminium is possible. Both needle-like and bulk AlN single crystals, up to 1 cm and 1 mm, respectively, have been obtained.

  15. Laser direct synthesis of graphene on quartz

    OpenAIRE

    Wei, Dapeng; Mitchell, James I.; Tansarawiput, Chookiat; Nam, Woongsik; Qi, Minghao; Ye, Peide D.; Xu, Xianfan

    2013-01-01

    We demonstrate a laser-based technique to directly synthesize few layer graphene on quartz substrates without using any metal catalyst. In our approach, a photoresist S-1805 (from Shipley Comp.) film coated on quartz wafers was heated, and then decomposed, by irradiation of a continuous-wave laser. The carbon atoms from the photoresist were dissolved in the molten quartz, and then extracted to form graphene when the temperature of the quartz was decreased. Raman spectroscopy shows the as-prod...

  16. Local Synthesis of Carbon Nanotubes in Silicon Microsystems: The Effect of Temperature Distribution on Growth Structure

    Science.gov (United States)

    Ta, Bao Q.; Haugen, Tormod B.; Hoivik, Nils; Halvorsen, Einar; Aasmundtveit, Knut E.

    2013-01-01

    Local synthesis and direct integration of carbon nanotubes (CNTs) into microsystems is a promising method for producing CNT-based devices in a single step, low-cost, and wafer-level, CMOS/MEMS-compatible process. In this report, the structure of the locally grown CNTs are studied by transmission imaging in scanning electron microscopy—S(T)EM. The characterization is performed directly on the microsystem, without any post-synthesis processing required. The results show an effect of temperature on the structure of CNTs: high temperature favors thin and regular structures, whereas low temperature favors “bamboo-like" structures. PMID:28811428

  17. Local Synthesis of Carbon Nanotubes in Silicon Microsystems: The Effect of Temperature Distribution on Growth Structure

    Directory of Open Access Journals (Sweden)

    Knut E. Aasmundtveit

    2013-07-01

    Full Text Available Local synthesis and direct integration of carbon nanotubes (CNTs into microsystems is a promising method for producing CNT-based devices in a single step, low-cost, and wafer-level, CMOS/MEMS-compatible process. In this report, the structure of the locally grown CNTs are studied by transmission imaging in scanning electron microscopy—S(TEM. The characterization is performed directly on the microsystem, without any post-synthesis processing required. The results show an effect of temperature on the structure of CNTs: high temperature favors thin and regular structures, whereas low temperature favors “bamboo-like” structures.

  18. Oxidative amide synthesis directly from alcohols with amines.

    Science.gov (United States)

    Chen, Cheng; Hong, Soon Hyeok

    2011-01-07

    Transition metal catalyzed oxidative amide synthesis directly from primary alcohols and amines is a highly atom economical transformation that evolves hydrogen gas as the only by-product. Several Ru-, Rh-based homogeneous and Ag-based heterogeneous catalysts have been developed for direct amide synthesis. Most of the developed catalysts showed excellent activity with sterically unhindered alcohols and amines; however, limited activity was observed with sterically hindered alcohols or amines, less basic aryl amines, and secondary amines. This account provides an overview of recent advances and challenges in direct amide synthesis.

  19. Direct Hydrothermal Synthesis of Carbonaceous Silver Nanocables for Electrocatalytic Applications.

    Science.gov (United States)

    Chen, Chuyang; Suryanto, Bryan Harry Rahmat; Zhao, Chuan; Jiang, Xuchuan; Yu, Aibing

    2015-08-05

    This study demonstrates a facile but efficient hydrothermal method for the direct synthesis of both carbonaceous silver (Ag@C core-shell) nanocables and carbonaceous nanotubes under mild conditions (particles into the carbonaceous tubes to form core-shell structures. The formation mechanism of carbonaceous silver nanostructures depending upon temperature is also discussed. Finally, the electrocatalytic performance of the as-prepared Ag@C nanocables is assessed for the oxidation reduction reaction and found to be very active but much less costly than the commonly used platinum catalysts. The findings should be useful for designing and constructing carbonaceous-metal nanostructures with potential applications in conductive materials, catalysts, and biosensors. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. DIRECT SYNTHESIS OF TERTIARY AMINES IN WATER USING MICROWAVES

    Science.gov (United States)

    A direct synthesis of tertiary amines is presented that proceeds expeditiously via N-alkylation of amines using alkyl halides in alkaline aqueous medium. This environmentally benign reaction is accelerated upon exposure to microwave irradiation resulting in shortened reaction tim...

  1. Nickel-catalyzed direct synthesis of dialkoxymethane ethers

    Indian Academy of Sciences (India)

    catalyzed direct synthesis of dialkoxymethane ethers. MURUGAN SUBARAMANIAN ABHIJIT BERA BHAGAVATULA L V PRASAD EKAMBARAM BALARAMAN. RAPID COMMUNICATION Volume 129 Issue 8 August 2017 pp 1153-1159 ...

  2. Direct synthesis of macrodiolides via hafnium(IV) catalysis.

    Science.gov (United States)

    de Léséleuc, Mylène; Collins, Shawn K

    2015-07-04

    Efficient direct synthesis of macrodiolides via catalysis using Hf(OTf)4 is possible in high yields, forming water as the sole by-product. The first protocol for the direct synthesis of macrodiolides from equimolar mixtures of diols and dicarboxylic acids was developed (58-96%). In addition, modification of the reaction concentration allows for the synthesis of head-to-tail macrodiolides from the corresponding seco acids. The catalytic preparation of the macrodiolides using a commercially available catalyst without the need for slow addition or azeotropic condition provides an operationally simple alternative to protocols which employ toxic tin catalysts or stoichiometric activation strategies.

  3. Room temperature synthesis of biodiesel using sulfonated graphitic carbon nitride

    Science.gov (United States)

    Sulfonation of graphitic carbon nitride (g-CN) affords a polar and strongly acidic catalyst, Sg-CN, which displays unprecedented reactivity and selectivity in biodiesel synthesis and esterification reactions at room temperature.

  4. Application of low-temperature plasma for the synthesis of hydrogenated graphene (graphane)

    Science.gov (United States)

    Shavelkina, M. B.; Amirov, R. H.; Katarzhis, V. A.; Kiselev, V. I.

    2017-12-01

    The possibility of a direct synthesis of hydrogenated graphene in decomposition of methane by means of low-temperature plasma was investigated. A DC plasma torch with an expanding channel-anode, a vortex gas supply and a self-setting arc length was used as a generator of low-temperature plasma. Argon was used as the plasma-forming gas. The temperatures of argon plasma and with methane addition to it were determined on the basis of spectral measurements. The synthesis products were characterized by electron microscopy and thermogravimetry. The effect of hydrogenated graphene as a nanomodifier on the properties of the cubic boron nitride based functional ceramics was investigated.

  5. Low-temperature synthesis of silicon carbide powder using shungite

    Energy Technology Data Exchange (ETDEWEB)

    Gubernat, A.; Pichor, W.; Lach, R.; Zientara, D.; Sitarz, M.; Springwald, M.

    2017-07-01

    The paper presents the results of investigation the novel and simple method of synthesis of silicon carbide. As raw material for synthesis was used shungite, natural mineral rich in carbon and silica. The synthesis of SiC is possible in relatively low temperature in range 1500–1600°C. It is worth emphasising that compared to the most popular method of SiC synthesis (Acheson method where the temperature of synthesis is about 2500°C) the proposed method is much more effective. The basic properties of products obtained from different form of shungite and in wide range of synthesis temperature were investigated. The process of silicon carbide formation was proposed and discussed. In the case of synthesis SiC from powder of raw materials the product is also in powder form and not requires any additional process (crushing, milling, etc.). Obtained products are pure and after grain classification may be used as abrasive and polishing powders. (Author)

  6. Low-temperature synthesis of silicon carbide powder using shungite

    Directory of Open Access Journals (Sweden)

    Agnieszka Gubernat

    2017-01-01

    Full Text Available The paper presents the results of investigation the novel and simple method of synthesis of silicon carbide. As raw material for synthesis was used shungite, natural mineral rich in carbon and silica. The synthesis of SiC is possible in relatively low temperature in range 1500–1600 °C. It is worth emphasising that compared to the most popular method of SiC synthesis (Acheson method where the temperature of synthesis is about 2500 °C the proposed method is much more effective. The basic properties of products obtained from different form of shungite and in wide range of synthesis temperature were investigated. The process of silicon carbide formation was proposed and discussed. In the case of synthesis SiC from powder of raw materials the product is also in powder form and not requires any additional process (crushing, milling, etc.. Obtained products are pure and after grain classification may be used as abrasive and polishing powders.

  7. Direct synthesis of Sr{sub 3}Al{sub 2}(OH){sub 12} from solution for preparation of fine-grained Sr{sub 3}Al{sub 2}O{sub 6} phosphors at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Jianquan, E-mail: jianquanqi@mail.tsinghua.edu.cn [School of Nature Resources & Materials Science, Northeastern University at Qinhuangdao, Qinhuangdao, Hebei Province 066004 (China); Zhang, Xinyi [School of Chemistry, Monash University, Clayton, Victoria 3800 (Australia); Han, Xiumei [School of Nature Resources & Materials Science, Northeastern University at Qinhuangdao, Qinhuangdao, Hebei Province 066004 (China); Li, Yuanyuan; Wu, Xueyang [School of Chemistry, Monash University, Clayton, Victoria 3800 (Australia); Zhong, Ruixia; Guo, Rui [School of Nature Resources & Materials Science, Northeastern University at Qinhuangdao, Qinhuangdao, Hebei Province 066004 (China)

    2016-09-05

    The precursors Sr{sub 3}Al{sub 2}(OH){sub 12} can be directly precipitated from solution near room temperature under the normal pressure. The cubic Sr{sub 3}Al{sub 2}O{sub 6} with fine grain size can be synthesized from Sr{sub 3}Al{sub 2}(OH){sub 12} at the temperature as low as 600 °C. Especially, the rare earth element, such as Eu{sup 3+} etc., as luminescent center, has been simultaneously integrated into the lattices of Sr{sub 3}Al{sub 2}O{sub 6}. The luminescent intensities of the samples annealed at a temperature over 800 °C are strong enough for phosphors, and increase with the annealing temperatures, reach a maximum at 1200 °C and then drop down at 1300 °C. The grain sizes of all the samples annealed below 1200 °C are smaller than 1 μm and suitable for mixing with other phosphors in the applications. The photoluminescent spectra of the Sr{sub 3}Al{sub 2}O{sub 6}:Eu{sup 3+} reveal that the intensities of both emission and excitation peaks increase with the dose of Eu{sup 3+}, and reach maxima at the dose level about 1.2%, then decrease due to concentration quenching. A new excitation band at 230 nm has been observed in heavier doped samples due to the complex point defects produced by association. - Graphical abstract: A novel strategy to prepare a stable hydroxide Sr{sub 3}Al{sub 2}(OH){sub 12} is developed. The strontium aluminates phosphors Eu{sup 3+} doped Sr{sub 3}Al{sub 2}O{sub 6} phosphors with controlled composition can been obtained at a low temperature by using Sr{sub 3}Al{sub 2}(OH){sub 12} as a precursor. - Highlights: • Sr{sub 3}Al{sub 2}(OH){sub 12} can be directly deposited from solution. • Sr{sub 3}Al{sub 2}O{sub 6} can be synthesized from Sr{sub 3}Al{sub 2}(OH){sub 12} at the temperature as low as 600 °C. • Luminescent center integrated into the lattices of Sr{sub 3}Al{sub 2}O{sub 6} at low temperature. • The phosphors with fine grain size and the strong luminescent intensities. • A new excitation band at 230 nm has been

  8. Temperature-enhanced synthesis of DMSO-Melanin

    Science.gov (United States)

    Piacenti-Silva, M.; Bronze-Uhle, E. S.; Paulin, J. V.; Graeff, C. F. O.

    2014-01-01

    Melanins are a class of pigmentary conjugated macromolecules found in many biological systems. Functionalization of synthetic melanin provides interesting new properties like the greater solubility of melanin synthesized in dimethyl sulfoxide, D-Melanin. In this work we have studied the influence of temperature on D-Melanin synthesis and its properties. To this end, UV-Vis, Fourier-transform infrared (FTIR) spectroscopy and Nuclear Magnetic Resonance (NMR) techniques have been employed to analyze D-Melanin synthesized within the range of 25-100 °C. Our results reveal that by increasing the synthesis temperature up to 100 °C, the synthesis time can be decreased by a factor of 7 when compared to room temperature. From FTIR and 13C CP/MAS NMR analyses the increase in temperature causes a decrease in the number of carbonyl groups from carboxylic acid and from ionized carboxylic acid. The decarboxylation of D-Melanin monomers at higher temperatures shows that the use of higher synthesis temperatures influences the elimination of carbonyls present in the precursor molecules, thus facilitating the polymerization of D-Melanin.

  9. Control of bacteriophage-induced enzyme synthesis in cells infected with a temperature-sensitive mutant.

    Science.gov (United States)

    Mathews, C K; Kessin, R H

    1967-02-01

    The timing of "early" and "late" protein synthesis in Escherichia coli infected with T-even bacteriophage was studied with a temperature-sensitive phage mutant, T4 tsL13. This strain was completely unable to direct the synthesis of phage deoxyribonucleic acid (DNA) at 44 C because it makes a deoxycytidylate hydroxymethylase which cannot act at that temperature. However, the mutant did multiply normally at 30 C. No detectable formation of the late protein, lysozyme, occurred at 44 C, in agreement with the idea, proposed by several workers, that DNA replication is necessary for activation of late genetic functions. However, the formation of an early enzyme, thymidylate synthetase, was shut off at about 10 min, as in normal infection. This implied that separate mechanisms were responsible for cessation of early functions and activation of late ones. That the infected cell at 44 C retained the capacity for synthesis of early enzymes was shown by the fact that DNA synthesis occurred after a culture was transferred from 44 to 30 C as late as 30 min after infection. This synthesis was inhibited by chloramphenicol, indicating that de novo synthesis of an early enzyme can take place at a late period in development. It is suggested that cells infected under normal conditions maintained an appreciable rate of early enzyme synthesis throughout the course of infection.

  10. Directed synthesis of stable large polyoxomolybdate spheres.

    Science.gov (United States)

    Roy, Soumyajit; Bossers, Lydia C A M; Meeldijk, Hans J D; Kuipers, Bonny W M; Kegel, Willem K

    2008-02-05

    Polyoxometalates or POMs, a class of inorganic transition metal-oxide based clusters, have gained significant interest owing to their catalytic, magnetic, and material science applications. All such applications require high surface area POM based materials. However, chemically synthesized POMs are still at most in the range of a few nanometers, with their size and morphology being difficult to control. Hence, there is an immediate need to develop design principles that allow easy control of POM morphology and size on mesoscopic (50-500 nm) length scales. Here, we report a design strategy to meet this need. Our method reported here avoids a complex chemical labyrinth by using a prefabricated cationic 1,2-dioleol-3-trimethylammonium-propane (DOTAP) vesicle as a scaffold/structure directing agent and gluing simple anionic heptamolybdates by electrostatic interaction and hydrogen bonds to form large POM spheres. By this method, complexity in the resulting structure can be deliberately induced either via the scaffold or via the oxometalate. The high degree of control in the matter of the size and morphology of the resulting POM superstructures renders this method attractive from a synthetic standpoint.

  11. Moderate Temperature Synthesis of Mesoporous Carbon

    KAUST Repository

    Dua, Rubal

    2013-01-03

    Methods and composition for preparation of mesoporous carbon material are provided. For example, in certain aspects methods for carbonization and activation at selected temperature ranges are described. Furthermore, the invention provides products prepared therefrom.

  12. Switching off hydrogen peroxide hydrogenation in the direct synthesis process.

    Science.gov (United States)

    Edwards, Jennifer K; Solsona, Benjamin; N, Edwin Ntainjua; Carley, Albert F; Herzing, Andrew A; Kiely, Christopher J; Hutchings, Graham J

    2009-02-20

    Hydrogen peroxide (H2O2) is an important disinfectant and bleach and is currently manufactured from an indirect process involving sequential hydrogenation/oxidation of anthaquinones. However, a direct process in which H2 and O2 are reacted would be preferable. Unfortunately, catalysts for the direct synthesis of H2O2 are also effective for its subsequent decomposition, and this has limited their development. We show that acid pretreatment of a carbon support for gold-palladium alloy catalysts switches off the decomposition of H2O2. This treatment decreases the size of the alloy nanoparticles, and these smaller nanoparticles presumably decorate and inhibit the sites for the decomposition reaction. Hence, when used in the direct synthesis of H2O2, the acid-pretreated catalysts give high yields of H2O2 with hydrogen selectivities greater than 95%.

  13. Synthesis of Directional Sources Using Wave Field Synthesis, Possibilities, and Limitations

    Directory of Open Access Journals (Sweden)

    Corteel E

    2007-01-01

    Full Text Available The synthesis of directional sources using wave field synthesis is described. The proposed formulation relies on an ensemble of elementary directivity functions based on a subset of spherical harmonics. These can be combined to create and manipulate directivity characteristics of the synthesized virtual sources. The WFS formulation introduces artifacts in the synthesized sound field for both ideal and real loudspeakers. These artifacts can be partly compensated for using dedicated equalization techniques. A multichannel equalization technique is shown to provide accurate results thus enabling for the manipulation of directional sources with limited reconstruction artifacts. Applications of directional sources to the control of the direct sound field and the interaction with the listening room are discussed.

  14. Fabrication of spintronics device by direct synthesis of single-walled carbon nanotubes from ferromagnetic electrodes

    Directory of Open Access Journals (Sweden)

    Mohd Ambri Mohamed, Nobuhito Inami, Eiji Shikoh, Yoshiyuki Yamamoto, Hidenobu Hori and Akihiko Fujiwara

    2008-01-01

    Full Text Available We describe an alternative method for realizing a carbon nanotube spin field-effect transistor device by the direct synthesis of single-walled carbon nanotubes (SWNTs on substrates by alcohol catalytic chemical vapor deposition. We observed hysteretic magnetoresistance (MR at low temperatures due to spin-dependent transport. In these devices, the maximum ratio in resistance variation of MR was found to be 1.8%.

  15. Synthesis of 1-alkyl triazolium triflate room temperature ionic liquids ...

    Indian Academy of Sciences (India)

    Sci. Vol. 127, No. 9, September 2015, pp. 1539–1545. c Indian Academy of Sciences. DOI 10.1007/s12039-015-0919-6. Synthesis of 1-alkyl triazolium triflate room temperature ionic liquids and their catalytic studies in multi-component Biginelli reaction. SANKARANARAYANAN NAGARAJAN, TANVEER M SHAIKH and.

  16. Novel Dodecaarylporphyrins: Synthesis and Variable Temperature NMR Studies

    Energy Technology Data Exchange (ETDEWEB)

    Cancilla, Mark; Lebrilla, Carlito; Ma, Jian-Guo; Medforth, Craig J.; Muzzi, Cinzia M.; Shelnutt, John A.; Smith, Kevin M.; Voss, Lisa

    1999-05-05

    An investigation of the synthesis of novel dodecaarylporphyrins using the Suzuki coupling reaction of arylboronic acids with octabromotetraarylporphyrins is reported. Studies of the dynamic properties of these new porphyrins using variable temperature (VT) 1H NMR spectroscopy and molecular mechanics provide interesting insights into their dynamic properties, including the first determination of {beta} aryl rotation in a porphyrin system.

  17. Microwave-assisted low temperature synthesis of sodium zirconium ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Microwave-assisted procedure for low temperature solid state synthesis of sodium zirconium phosphate (NZP), a material with the potential for immobilization and disposal of high level nuclear waste, was developed. Three selected fission products, namely, Cesium, Strontium and Tellurium were introduced ...

  18. Self-propagating high temperature synthesis and magnetic ...

    Indian Academy of Sciences (India)

    Ni–Zn ferrite powders were synthesized by self-propagating high temperature synthesis (SHS) method. X-ray diffraction, TEM and vibrating sample magnetometry (VSM) were used to characterize the phase composition, microstructure and magnetic properties of the combustion products. The effect of the combustion ...

  19. Microwave-assisted low temperature synthesis of sodium zirconium ...

    Indian Academy of Sciences (India)

    assisted low temperature synthesis of sodium zirconium phosphate (NZP) and the leachability of some selected fission products incorporated in its structure - A case study of leachability of cesium. A H Naik S B Deb A B Chalke M K Saxena K L ...

  20. Combustion and Plasma Synthesis of High-Temperature Materials

    Science.gov (United States)

    Munir, Z. A.; Holt, J. B.

    1997-04-01

    KEYNOTE ADDRESS. Self-Propagating High-Temperature Synthesis: Twenty Years of Search and Findings (A. Merzhanov). SOLID-STATE COMBUSTION SYNTHESIS. Recent Progress in Combustion Synthesis of High-Performance Materials in Japan (M. Koizumi & Y. Miyamoto). Modeling and Numerical Computation of a Nonsteady SHS Process (A. Bayliss & B. Matkowsky). New Models of Quasiperiodic Burning in Combustion Synthesis (S. Margolis, et al.). Modeling of SHS Operations (V. Hlavacek, et al.). Combustion Theory for Sandwiches of Alloyable Materials (R. Armstrong & M. Koszykowski). Observations on the Combustion Reaction Between Thin Foils of Ni and Al (U. Anselmi-Tamburini & Z. Munir). Combustion Synthesis of Intermetallic Compounds (Y. Kaieda, et al.). Combustion Synthesis of Nickel Aluminides (B. Rabin, et al.). Self-Propagating High-Temperature Synthesis of NiTi Intermetallics (H. Yi & J. Moore). Shock-Induced Chemical Synthesis of Intermetallic Compounds (S. Work, et al.). Advanced Ceramics Via SHS (T. DeAngelis & D. Weiss). In-Situ Formation of SiC and SiC-C Blocked Solids by Self-Combustion Synthesis (S. Ikeda, et al.). Powder Purity and Morphology Effects in Combustion-Synthesis Reactions (L. Kecskes, et al.). Simultaneous Synthesis and Densification of Ceramic Components Under Gas Pressure by SHS (Y. Miyamoto & M. Koizumi). The Use of Self-Propagating High-Temperature Synthesis of High-Density Titanium Diboride (P. Zavitsanos, et al.). Metal--Ceramic Composite Pipes Produced by a Centrifugal-Thermit Process (O. Odawara). Simultaneous Combustion Synthesis and Densification of AIN (S. Dunmead, et al.). Fabrication of a Functionally Gradient Material by Using a Self-Propagating Reaction Process (N. Sata, et al.). Combustion Synthesis of Oxide-Carbide Composites (L. Wang, et al.). Heterogeneous Reaction Mechanisms in the Si-C System Under Conditions of Solid Combustion (R. Pampuch, et al.). Experimental Modeling of Particle-Particle Interactions During SHS of TiB2 -Al2O3 (K. Logan

  1. Direct-reading dial for noise temperature and noise resistance

    DEFF Research Database (Denmark)

    Diamond, J.M.

    1967-01-01

    An attenuator arrangement for a noise generator is described. The scheme permits direct reading of both noise resistance and noise temperature¿the latter with a choice of source resistance.......An attenuator arrangement for a noise generator is described. The scheme permits direct reading of both noise resistance and noise temperature¿the latter with a choice of source resistance....

  2. Multi-Temperature Zone, Droplet-based Microreactor for Increased Temperature Control in Nanoparticle Synthesis

    KAUST Repository

    Erdem, E. Yegân

    2013-12-12

    Microreactors are an emerging technology for the controlled synthesis of nanoparticles. The Multi-Temperature zone Microreactor (MTM) described in this work utilizes thermally isolated heated and cooled regions for the purpose of separating nucleation and growth processes as well as to provide a platform for a systematic study on the effect of reaction conditions on nanoparticle synthesis. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. ROOM TEMPERATURE BULK SYNTHESIS OF SILVER NANOCABLES WRAPPED WITH POLYPYRROLE

    Science.gov (United States)

    Wet chemical synthesis of silver cables wrapped with polypyrrole is reported in aqueous media without use of any surfactant/capping agent and/or template. The method employs direct polymerization of pyrrole of an aqueous solution with AgNO3 as an oxidizing agent. The four probe c...

  4. Search Directions for Direct H2O2 Synthesis Catalysts Starting from Au-12 Nanoclusters

    DEFF Research Database (Denmark)

    Grabow, Lars; Larsen, Britt Hvolbæk; Falsig, Hanne

    2012-01-01

    We present density functional theory calculations on the direct synthesis of H2O2 from H-2 and O-2 over an Au-12 corner model of a gold nanoparticle. We first show a simple route for the direct formation of H2O2 over a gold nanocatalyst, by studying the energetics of 20 possible elementary...... that the rate of H2O2 and H2O formation can be determined from a single descriptor, namely, the binding energy of oxygen (E-O). Our model predicts the search direction starting from an Au-12 nanocluster for an optimal catalyst in terms of activity and selectivity for direct H2O2 synthesis. Taking also stability...

  5. Alcohol synthesis in a high-temperature slurry reactor

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, G.W.; Marquez, M.A.; McCutchen, M.S. [North Carolina State Univ., Raleigh, NC (United States)

    1995-12-31

    The overall objective of this contract is to develop improved process and catalyst technology for producing higher alcohols from synthesis gas or its derivatives. Recent research has been focused on developing a slurry reactor that can operate at temperatures up to about 400{degrees}C and on evaluating the so-called {open_quotes}high pressure{close_quotes} methanol synthesis catalyst using this reactor. A laboratory stirred autoclave reactor has been developed that is capable of operating at temperatures up to 400{degrees}C and pressures of at least 170 atm. The overhead system on the reactor is designed so that the temperature of the gas leaving the system can be closely controlled. An external liquid-level detector is installed on the gas/liquid separator and a pump is used to return condensed slurry liquid from the separator to the reactor. In order to ensure that gas/liquid mass transfer does not influence the observed reaction rate, it was necessary to feed the synthesis gas below the level of the agitator. The performance of a commercial {open_quotes}high pressure {close_quotes} methanol synthesis catalyst, the so-called {open_quotes}zinc chromite{close_quotes} catalyst, has been characterized over a range of temperature from 275 to 400{degrees}C, a range of pressure from 70 to 170 atm., a range of H{sub 2}/CO ratios from 0.5 to 2.0 and a range of space velocities from 2500 to 10,000 sL/kg.(catalyst),hr. Towards the lower end of the temperature range, methanol was the only significant product.

  6. Direct Synthesis of 7 nm Thick Zinc(II)-Benzimidazole-Acetate Metal-Organic Framework Nanosheets

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Feng; Kumar, Prashant; Xu, Wenqian; Mkhoyan, K. Andre; Tsapatsis, Michael

    2018-01-09

    Two-dimensional metal-organic frameworks (MOFs) are promising candidates for high performance gas sepa-ration membranes. Currently, MOF nanosheets are mostly fabricated through delamination of layered MOFs, which often re-sults in a low yield of intact free-standing nanosheets. In this work, we present a direct synthesis method for zinc(II)-benzimidazole-acetate (Zn(Bim)OAc) MOF nanosheets. The obtained nanosheets have a lateral dimension of 600 nm when synthesized at room temperature. By adjusting the synthesis temperature, the morphology of obtained nanosheets can be readily tuned from nanosheets to nanobelts. A thickness of 7 nm is determined for Zn(Bim)OAc using high-angle annular dark-field scanning transmission electron microscopy, which makes these nanosheets promising building blocks of gas sepa-ration membranes.

  7. Effect of direction on loudness in individual binaural synthesis

    DEFF Research Database (Denmark)

    Sivonen, Ville Pekka; Minnaar, Pauli; Ellermeier, Wolfgang

    2005-01-01

    The effect of sound incidence angle on loudness is investigated in this study using binaural synthesis. Individual head-related transfer functions (HRTFs) and headphone equalization are used to present narrow-band noises from different directions to listeners. Their task is to match the loudness...... of these stimuli in an adaptive procedure to a reference noise in front of the listeners. The results are compared to an earlier investigation with the same experimental design in a real sound field. Based on the results the role of the individual HRTFs in loudness judgments is inspected, and finally, binaural...

  8. Synthesis of Bottom Hole Temperatures and Heat Flow Data

    Science.gov (United States)

    Gosnold, W. D.; Crowell, A. M.

    2012-12-01

    The development of a National Geothermal Data System (http://www.geothermaldata.org/) promises to provide industry, governmental agencies and researchers with a wealth of data on United States geothermal resources. Two of the larger data sets in the NDGS effort are the bottom-hole temperature data set from oil and gas drilling and the heat flow data set. The BHT data are being compiled by state geological surveys in a Bore Hole Observation Template that can include up to 76 different attributes for each well. The heat flow data are being compiled by a consortium led by the SMU Geothermal Laboratory in a Heat Flow Template that can include up to 63 different atrributes for each heat flow site. The key data for geothermal resource development are temperature, depth and the reservoir properties that control production capacity. The UND geothermal laboratory has assembled the BHT and heat flow data sets for North Dakota, Nebraska and Minnesota and we have compared how accurately the key geothermal data may be independently determined from each data set and by synthesis of both data sets. The BHT data provide temperature at depth, but it is well-documented that BHT data were recorded at non-equilibrium conditions and generally underestimate actual formation temperatures. Heat flow data include a measured temperature gradient, although the gradient may apply to only a short segment of the borehole temperature measurement. Synthesis of these two data sets provides checks that can prevent errors in data interpretation. We compared BHT data from the Denver Basin and Williston Basin to equilibrium temperature vs. depth profiles measured in deep boreholes and developed a thermal stratigraphy approach that permits correction of the BHT data for each basin.

  9. Effect of Temperature and Catalyst Concentration on Polyglycerol during Synthesis

    Directory of Open Access Journals (Sweden)

    Carolina Ardila-Suárez

    2015-01-01

    Full Text Available Morphology, molecular weight, polydispersity, functionality, and thermal properties are important characteristics when using polyglycerol as a building block in the development of materials for industrial applications such as hydrogels, surfactants, asphalts additives, cosmetics, pharmaceutical, biomedical, and drug delivery systems. In this study several experimental techniques are used to understand the effect of process variables during synthesis in the catalyzed etherification of glycerol, a coproduct of biodiesel industry. Biobased polyglycerol is a high-valued product, which is useful as building block material because of its remarkable features, for instance, multiple hydrophilic groups, excellent biocompatibility, and highly flexible aliphatic polyether backbone. A connection between polyglycerol characteristics and process variables during synthesis allows the control of glycerol polymerization through reaction conditions. We show that temperature and catalyst concentration can be tuned with the aim of tailoring fundamental polyglycerol parameters including molecular weight, polydispersity, morphology, and functionality.

  10. Directional transport of droplets on wettability patterns at high temperature

    Science.gov (United States)

    Huang, Shuai; Yin, Shaohui; Chen, Fengjun; Luo, Hu; Tang, Qingchun; Song, Jinlong

    2018-01-01

    Directional transport of liquid has attracted increasing interest owing to its potential of application in lab-on-a-chip, microfluidic devices and thermal management technologies. Although numerous strategies have been developed to achieve directional transport of liquid at low temperature, controlling the directional transport of liquid at high temperature remains to be a challenging issue. In this work, we reported a novel strategy in which different parts of droplet contacted with surface with different wettability patterns, resulting in a discrepant evaporative vapor film to achieve the directional transport of liquid. The experimental results showed that the state of the liquid on wettability patterned surface gradually changed from contact boiling to Leidenfrost state with the increase of substrate temperature Ts, and liquid on superhydrophilic surface was in composite state of contact boiling and Leidenfrost when Ts was higher than 200 °C. Inspired by the different evaporation states of droplet on the wettability boundary, controlling preferential motion of droplets was observed at high temperature. By designing a surface with wettability pattern on which superhydrophobic region and superhydrophilic region are alternately arranged, a controlled directional transport of droplet can be achieved at high temperature.

  11. Direct cooling of polar molecules to sub-millikelvin temperatures

    CERN Document Server

    Prehn, Alexander; Glöckner, Rosa; Rempe, Gerhard; Zeppenfeld, Martin

    2015-01-01

    We demonstrate direct cooling of gaseous formaldehyde (H2CO) to the microkelvin regime. Our approach, optoelectrical Sisyphus cooling, provides a simple dissipative cooling method applicable to electrically trapped dipolar molecules. By reducing the temperature by three orders of magnitude and increasing the phase-space density by a factor of ~$10^4$ we generate an ensemble of $3\\cdot10^5$ molecules with a temperature of about 420\\mu K, populating a single rotational state with more than 80% purity.

  12. Self-propagating high-temperature synthesis of tool steel

    Science.gov (United States)

    Evtushenko, A. T.; Pazare, S.; Torbunov, S. S.

    2007-03-01

    The process of fabrication of a high-hardness alloy with the help of self-propagating high-temperature synthesis due to combustion of thermit from powdered cinder, aluminum, and titanium carbide is studied. The effect of the mass fraction of the titanium carbide powder and of additives of powdered titanium diboride, molybdenum, and alloy cast iron and the effect of the fineness of the blend and the heat treatment mode on the combustion process, the chemical composition, the structure, and the hardness of the alloy obtained are estimated.

  13. Temperature-feedback direct laser reshaping of silicon nanostructures

    Science.gov (United States)

    Aouassa, M.; Mitsai, E.; Syubaev, S.; Pavlov, D.; Zhizhchenko, A.; Jadli, I.; Hassayoun, L.; Zograf, G.; Makarov, S.; Kuchmizhak, A.

    2017-12-01

    Direct laser reshaping of nanostructures is a cost-effective and fast approach to create or tune various designs for nanophotonics. However, the narrow range of required laser parameters along with the lack of in-situ temperature control during the nanostructure reshaping process limits its reproducibility and performance. Here, we present an approach for direct laser nanostructure reshaping with simultaneous temperature control. We employ thermally sensitive Raman spectroscopy during local laser melting of silicon pillar arrays prepared by self-assembly microsphere lithography. Our approach allows establishing the reshaping threshold of an individual nanostructure, resulting in clean laser processing without overheating of the surrounding area.

  14. High Temperature 300°C Directional Drilling System

    Energy Technology Data Exchange (ETDEWEB)

    Chatterjee, Kamalesh [Baker Hughes Oilfield Operations, Houston, TX (United States); Aaron, Dick [Baker Hughes Oilfield Operations, Houston, TX (United States); Macpherson, John [Baker Hughes Oilfield Operations, Houston, TX (United States)

    2015-07-31

    Many countries around the world, including the USA, have untapped geothermal energy potential. Enhanced Geothermal Systems (EGS) technology is needed to economically utilize this resource. Temperatures in some EGS reservoirs can exceed 300°C. To effectively utilize EGS resources, an array of injector and production wells must be accurately placed in the formation fracture network. This requires a high temperature directional drilling system. Most commercial services for directional drilling systems are rated for 175°C while geothermal wells require operation at much higher temperatures. Two U.S. Department of Energy (DOE) Geothermal Technologies Program (GTP) projects have been initiated to develop a 300°C capable directional drilling system, the first developing a drill bit, directional motor, and drilling fluid, and the second adding navigation and telemetry systems. This report is for the first project, “High Temperature 300°C Directional Drilling System, including drill bit, directional motor and drilling fluid, for enhanced geothermal systems,” award number DE-EE0002782. The drilling system consists of a drill bit, a directional motor, and drilling fluid. The DOE deliverables are three prototype drilling systems. We have developed three drilling motors; we have developed four roller-cone and five Kymera® bits; and finally, we have developed a 300°C stable drilling fluid, along with a lubricant additive for the metal-to-metal motor. Metal-to-metal directional motors require coatings to the rotor and stator for wear and corrosion resistance, and this coating research has been a significant part of the project. The drill bits performed well in the drill bit simulator test, and the complete drilling system has been tested drilling granite at Baker Hughes’ Experimental Test Facility in Oklahoma. The metal-to-metal motor was additionally subjected to a flow loop test in Baker Hughes’ Celle Technology Center in Germany, where it ran for more than 100

  15. Synthesis of indium nanoparticles at ambient temperature; simultaneous phase transfer and ripening

    Energy Technology Data Exchange (ETDEWEB)

    Aghazadeh Meshgi, Mohammad; Kriechbaum, Manfred [Graz University of Technology, Institute of Inorganic Chemistry (Austria); Biswas, Subhajit; Holmes, Justin D., E-mail: j.holmes@ucc.ie [University College Cork, Materials Chemistry and Analysis Group, Department of Chemistry and the Tyndall National Institute (Ireland); Marschner, Christoph, E-mail: christoph.marschner@tugraz.at [Graz University of Technology, Institute of Inorganic Chemistry (Austria)

    2016-12-15

    The synthesis of size-monodispersed indium nanoparticles via an innovative simultaneous phase transfer and ripening method is reported. The formation of nanoparticles occurs in a one-step process instead of well-known two-step phase transfer approaches. The synthesis involves the reduction of InCl{sub 3} with LiBH{sub 4} at ambient temperature and although the reduction occurs at room temperature, fine indium nanoparticles, with a mean diameter of 6.4 ± 0.4 nm, were obtained directly in non-polar n-dodecane. The direct synthesis of indium nanoparticles in n-dodecane facilitates their fast formation and enhances their size-monodispersity. In addition, the nanoparticles were highly stable for more than 2 months. The nanoparticles were characterised by dynamic light scattering (DLS), small angle X-ray scattering (SAXS), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared (FT-IR) spectroscopy to determine their morphology, structure and phase purity.

  16. Electron Temperature of the Arc Discharge for Nanomaterial Synthesis

    Science.gov (United States)

    Feurer, Matthew; Vekselman, Vladislav; Startton, Brentley; Raitses, Yevgeny; LaboratoryPlasma Nanosynthesis Team

    2016-10-01

    Since the discovery of different allotropes of carbon in the twentieth century many uses have been found for carbon based nanomaterials such as buckyballs, nanotubes (CNTs), and graphene. An atmospheric pressure arc discharge with graphite electrodes is a promising technique for producing large volumes of these carbon nanostructures. Plasma drives the synthesis providing carbon feedstock by anode ablation and sustaining required composition and temperature of nanomaterial species, as such it is important to characterize the plasma used in this process in order to control the quality and attributes of the resulting carbon nanostructures. In work we present detailed in-situ measurements of spatial distribution of arc plasma parameters obtained with optical emission spectroscopy (OES) diagnostics. The plasma temperature has been determined using Boltzmann diagram method with collisional radiative modeling due to plasma deviation from complete local thermodynamic equilibrium (LTE). Results of these measurements demonstrate a strong correlation between arc plasma and synthesis processes. This work was supported by US Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.

  17. Direct method for calculating temperature-dependent transport properties

    NARCIS (Netherlands)

    Liu, Y.; Yuan, Z.; Wesselink, R.J.H.; Starikov, A.A.; van Schilfgaarde, M.; Kelly, Paul J.

    2015-01-01

    We show how temperature-induced disorder can be combined in a direct way with first-principles scattering theory to study diffusive transport in real materials. Excellent (good) agreement with experiment is found for the resistivity of Cu, Pd, Pt (and Fe) when lattice (and spin) disorder are

  18. A direct method for the synthesis of orthogonally protected furyl- and thienyl- amino acids.

    Science.gov (United States)

    Hudson, Alex S; Caron, Laurent; Colgin, Neil; Cobb, Steven L

    2015-04-01

    The synthesis of unnatural amino acids plays a key part in expanding the potential application of peptide-based drugs and in the total synthesis of peptide natural products. Herein, we report a direct method for the synthesis of orthogonally protected 5-membered heteroaromatic amino acids.

  19. Passive radiative cooling below ambient air temperature under direct sunlight.

    Science.gov (United States)

    Raman, Aaswath P; Anoma, Marc Abou; Zhu, Linxiao; Rephaeli, Eden; Fan, Shanhui

    2014-11-27

    Cooling is a significant end-use of energy globally and a major driver of peak electricity demand. Air conditioning, for example, accounts for nearly fifteen per cent of the primary energy used by buildings in the United States. A passive cooling strategy that cools without any electricity input could therefore have a significant impact on global energy consumption. To achieve cooling one needs to be able to reach and maintain a temperature below that of the ambient air. At night, passive cooling below ambient air temperature has been demonstrated using a technique known as radiative cooling, in which a device exposed to the sky is used to radiate heat to outer space through a transparency window in the atmosphere between 8 and 13 micrometres. Peak cooling demand, however, occurs during the daytime. Daytime radiative cooling to a temperature below ambient of a surface under direct sunlight has not been achieved because sky access during the day results in heating of the radiative cooler by the Sun. Here, we experimentally demonstrate radiative cooling to nearly 5 degrees Celsius below the ambient air temperature under direct sunlight. Using a thermal photonic approach, we introduce an integrated photonic solar reflector and thermal emitter consisting of seven layers of HfO2 and SiO2 that reflects 97 per cent of incident sunlight while emitting strongly and selectively in the atmospheric transparency window. When exposed to direct sunlight exceeding 850 watts per square metre on a rooftop, the photonic radiative cooler cools to 4.9 degrees Celsius below ambient air temperature, and has a cooling power of 40.1 watts per square metre at ambient air temperature. These results demonstrate that a tailored, photonic approach can fundamentally enable new technological possibilities for energy efficiency. Further, the cold darkness of the Universe can be used as a renewable thermodynamic resource, even during the hottest hours of the day.

  20. Block copolymer directed synthesis of mesoporous TiO 2 for dye-sensitized solar cells

    KAUST Repository

    Nedelcu, Mihaela

    2009-01-01

    The morphology of TiO2 plays an important role in the operation of solid-state dye-sensitized solar cells. By using polyisoprene-block- ethyleneoxide (PI-b-PEO) copolymers as structure directing agents for a sol-gel based synthesis of mesoporous TiO2, we demonstrate a strategy for the detailed control of the semiconductor morphology on the 10 nm length scale. The careful adjustment of polymer molecular weight and titania precursor content is used to systematically vary the material structure and its influence upon solar cell performance is investigated. Furthermore, the use of a partially sp 2 hybridized structure directing polymer enables the crystallization of porous TiO2 networks at high temperatures without pore collapse, improving its performance in solid-state dye-sensitized solar cells. © 2009 The Royal Society of Chemistry.

  1. Self propagating high temperature synthesis of ferrites in magnetic fields

    CERN Document Server

    Affleck, L

    2002-01-01

    Self propagating high temperature synthesis (SHS) reactions have been performed on mixtures of BaO sub 2 , Fe and Fe sub 2 O sub 3 to form barium ferrite, BaFe sub 1 sub 2 O sub 1 sub 9. Reactions were conducted in zero field and in an applied magnetic field of 1.1 T with the aim of exploring the influence of the field. The temperature and velocity of the reactions were measured and the products, both post-SHS and post-annealing, were characterised by techniques including X-ray diffraction, Moessbauer spectroscopy, vibrating sample magnetometry and electron microprobe analysis. The applied magnetic field was found to lead to hotter and faster reactions, a greater degree of conversion of the reactants, a needle-like microstructure in the post-SHS product, and a reduced coercive field (approx 20-30 %) in the annealed product, compared to zero field. Sodium perchlorate was used as an internal oxidising agent, and found to produce similar effects. Correlations were observed between the temperature reached in the ...

  2. Direct recovery of boiler residue by combustion synthesis.

    Science.gov (United States)

    Nourbaghaee, Homan; Ghaderi Hamidi, Ahmad; Pourabdoli, Mahdi

    2018-01-08

    Boiler residue (BR) of thermal power plants is one of the important secondary sources for vanadium production. In this research, the aluminothermic self-propagating high-temperature synthesis (SHS) was used for recovering the transition metals of BR for the first time. The effects of extra aluminum as reducing agent and flux to aluminum ratio (CaO/Al) were studied and the efficiency of recovery and presence of impurities were measured. Aluminothermic reduction of vanadium and other metals was carried out successfully by SHS without any foreign heat source. Vanadium, iron, and nickel principally were reduced and gone into metallic master alloy as SHS product. High levels of efficiency (>80%) were achieved and the results showed that SHS has a great potential to be an industrial process for BR recovery. SHS produced two useful products. Metallic master alloy and fused glass slag that is applicable for ceramic industries. SHS can also neutralize the environmental threats of BR by a one step process. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Temperature measurement methods during direct heat arterial tissue fusion.

    Science.gov (United States)

    Cezo, James D; Kramer, Eric; Taylor, Kenneth D; Ferguson, Virginia; Rentschler, Mark E

    2013-09-01

    Fusion of biological tissues through direct and indirect heating is a growing area of medical research, yet there are still major gaps in understanding this procedure. Several companies have developed devices which fuse blood vessels, but little is known about the tissue's response to the stimuli. The need for accurate measurements of tissue behavior during tissue fusion is essential for the continued development and improvement of energy delivery devices. An experimental study was performed to measure the temperatures experienced during tissue fusion and the resulting burst pressure of the fused arteries. An array of thermocouples was placed in the lumen of a porcine splenic artery segment and sealed using a ConMed Altrus thermal fusion device. The temperatures within the tissue, in the device, and at the tissue-device interface were recorded. These measurements were then analyzed to calculate the temperature profile in the lumen of the artery. The temperature in the artery at the site of tissue fusion was measured to range from 142 to 163 °C using the ConMed Altrus. The corresponding burst pressure for arteries fused at this temperature was measured as 416 ± 79 mmHg. This study represents the first known experimental measurement of temperature at the site of vessel sealing found in the literature.

  4. Directed transport of Brownian particles in a changing temperature field

    Energy Technology Data Exchange (ETDEWEB)

    Grillo, A [DMFCI, Facolta di Ingegneria, Universita di Catania. Viale Andrea Doria 6, 95125 Catania (Italy); Jinha, A [HPL-Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, Alberta, T2N 1N4 (Canada); Federico, S [HPL-Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, Alberta, T2N 1N4 (Canada); Ait-Haddou, R [HPL-Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, Alberta, T2N 1N4 (Canada); Herzog, W [HPL-Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, Alberta, T2N 1N4 (Canada); Giaquinta, G [DMFCI, Facolta di Ingegneria, Universita di Catania. Viale Andrea Doria 6, 95125 Catania (Italy)

    2008-01-11

    We study the interaction of Brownian particles with a changing temperature field in the presence of a one-dimensional periodic adiabatic potential. We show the existence of directed transport through the determination of the overall current of Brownian particles crossing the boundary of the system. With respect to the case of Brownian particles in a thermal bath, we determine a current which exhibits a contribution explicitly related to the presence of a thermal gradient. Beyond the self-consistent calculation of the temperature and probability density distribution of Brownian particles, we evaluate the energy consumption for directed transport to take place. Our description is based on Streater's model, and solutions are obtained by perturbing the system from its initial thermodynamic equilibrium state.

  5. Controlled synthesis of pentagonal gold nanotubes at room temperature

    Science.gov (United States)

    Bi, Yingpu; Lu, Gongxuan

    2008-07-01

    Large quantities of pentagonal gold nanotubes have been synthesized by reducing chloroauric acid with silver nanowires in an aqueous solution of hexadecyltrimethylammonium bromide (CTAB) at room temperature. These gold nanotubes possess perfect structures, smooth surfaces, highly crystalline walls, and similar cross-sections to that of the silver template. In this process, the CTAB participation was found to be crucial for shape-controlled synthesis of pentagonal gold nanotubes. In the absence of CTAB, loose and hollow gold structures were routinely generated, while bundled gold nanotubes with rough surfaces were obtained by replacing the CTAB with poly(vinyl pyrrolidone) (PVP). The possible formation mechanism of pentagonal gold nanotubes has also been discussed on the basis of various growth stages studied by field-emission scanning electron microscopy (FE-SEM) images. In addition, the catalytic properties of these hollow nanostructures for hydrogen generation reaction from HCHO solution have also been investigated. They showed higher activity than that of spherical gold nanoparticles.

  6. Flow-directed synthesis of spatially variant arrays of branched zinc oxide mesostructures.

    Science.gov (United States)

    Konda, Abhiteja; Morin, Stephen A

    2017-06-22

    The use of fluid flow to control crystal morphology during the liquid-phase synthesis of inorganic nanomaterials is a relatively under explored approach. Synthetic strategies that take advantage of flow effects present the opportunity to tune several parameters (e.g., flow velocity and direction) in addition to conventional growth parameters (e.g., time, temperature, chemistry, and concentration), and thus enable additional levels of control in the bottom-up synthesis of nanomaterials. The current work reports the application of microfluidics to the rational synthesis of spatially variant arrays of branched zinc oxide (ZnO) nanorods with predictable morphological and compositional characteristics. Specifically, the dislocation driven growth rates of branches within ZnO nanorod arrays was rationally controlled using dynamic, high-velocity precursor flow, yielding ZnO mesostructures with morphology that depended on the location within the arrays. This approach compliments current synthetic strategies and is generally applicable to a range of materials with a diverse set of functional properties (e.g., optical, magnetic, electronic) and applications.

  7. Direct dimethyl ether high temperature polymer electrolyte membrane fuel cells

    DEFF Research Database (Denmark)

    Vassiliev, Anton; Jensen, Jens Oluf; Li, Qingfeng

    A high temperature polybenzimidazole (PBI) polymer fuel cell was fed with dimethyl ether (DME) and water vapour mixture on the anode at ambient pressure with air as oxidant. A peak power density of 79 mW/cm2 was achieved at 200°C. A conventional polymer based direct DME fuel cell is liquid fed an......V higher than that of methanol, indicating less fuel crossover.......A high temperature polybenzimidazole (PBI) polymer fuel cell was fed with dimethyl ether (DME) and water vapour mixture on the anode at ambient pressure with air as oxidant. A peak power density of 79 mW/cm2 was achieved at 200°C. A conventional polymer based direct DME fuel cell is liquid fed...... and suffers from low DME solubility in water. When the DME - water mixture is fed as vapour miscibility is no longer a problem. The increased temperature is more beneficial for the kinetics of the direct oxidation of DME than of methanol. The Open Circuit Voltage (OCV) with DME operation was 50 to 100 m...

  8. Room temperature synthesis and high temperature frictional study of silver vanadate nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Singh, D P; Aouadi, S M [Department of Physics, Southern Illinois University, Carbondale-62901 (United States); Polychronopoulou, K [Department of Chemistry, University of Cyprus, Nicosia, 1678 (Cyprus); Rebholz, C, E-mail: dineshpsingh@gmail.com, E-mail: saouadi@physics.siu.edu [Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, 1678 (Cyprus)

    2010-08-13

    We report the room temperature (RT) synthesis of silver vanadate nanorods (consisting of mainly {beta}-AgV O{sub 3}) by a simple wet chemical route and their frictional study at high temperatures (HT). The sudden mixing of ammonium vanadate with silver nitrate solution under constant magnetic stirring resulted in a pale yellow coloured precipitate. Structural/microstructural characterization of the precipitate through x-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed the high yield and homogeneous formation of silver vanadate nanorods. The length of the nanorods was 20-40 {mu}m and the thickness 100-600 nm. The pH variation with respect to time was thoroughly studied to understand the formation mechanism of the silver vanadate nanorods. This synthesis process neither demands HT, surfactants nor long reaction time. The silver vanadate nanomaterial showed good lubrication behaviour at HT (700 deg. C) and the friction coefficient was between 0.2 and 0.3. HT-XRD revealed that AgV O{sub 3} completely transformed into silver vanadium oxide (Ag{sub 2}V{sub 4}O{sub 11}) and silver with an increase in temperature from RT to 700 deg. C.

  9. The Nonstructural Proteins Directing Coronavirus RNA Synthesis and Processing.

    Science.gov (United States)

    Snijder, E J; Decroly, E; Ziebuhr, J

    2016-01-01

    Coronaviruses are animal and human pathogens that can cause lethal zoonotic infections like SARS and MERS. They have polycistronic plus-stranded RNA genomes and belong to the order Nidovirales, a diverse group of viruses for which common ancestry was inferred from the common principles underlying their genome organization and expression, and from the conservation of an array of core replicase domains, including key RNA-synthesizing enzymes. Coronavirus genomes (~26-32 kilobases) are the largest RNA genomes known to date and their expansion was likely enabled by acquiring enzyme functions that counter the commonly high error frequency of viral RNA polymerases. The primary functions that direct coronavirus RNA synthesis and processing reside in nonstructural protein (nsp) 7 to nsp16, which are cleavage products of two large replicase polyproteins translated from the coronavirus genome. Significant progress has now been made regarding their structural and functional characterization, stimulated by technical advances like improved methods for bioinformatics and structural biology, in vitro enzyme characterization, and site-directed mutagenesis of coronavirus genomes. Coronavirus replicase functions include more or less universal activities of plus-stranded RNA viruses, like an RNA polymerase (nsp12) and helicase (nsp13), but also a number of rare or even unique domains involved in mRNA capping (nsp14, nsp16) and fidelity control (nsp14). Several smaller subunits (nsp7-nsp10) act as crucial cofactors of these enzymes and contribute to the emerging "nsp interactome." Understanding the structure, function, and interactions of the RNA-synthesizing machinery of coronaviruses will be key to rationalizing their evolutionary success and the development of improved control strategies. © 2016 Elsevier Inc. All rights reserved.

  10. Low temperature direct propane polymer electrolyte membranes fuel cell (DPFC)

    Energy Technology Data Exchange (ETDEWEB)

    Savadogo, O.; Varela, F. J. R. [Ecole Polytechnique, Laboratoire d' electrochimie et de materiaux energetiques, Montreal, PQ (Canada)

    2001-04-01

    A low-temperature direct propane polymer electrolyte membrane fuel cell (DPFC) is demonstrated. The propane is fed into the fuel cell directly, eliminating the need for reforming. The key elements of the DPFC system are an appropriate catalyst for the anodes, an appropriate membrane and a propane humidifier. Overall, the system consists of a propane container, an oxygen container, a propane humidifier, and oxygen humidifier, a proton exchange membrane fuel cell (PEMFC), and a fuel cell station monitored by a computer. The membranes are Nafion 117, doped with heteropolyacids (HPAs) or polybenzimidazole (PBI). The fuel cell was built of graphite blocks in which flow fields were engraved, one for humidified propane, the other for oxygen. The anode was based on platinum, platinum-ruthenium, or platinum-chromium oxide electrocatalysts; the cathode was based on a platinum electrocatalyst. Results showed that polymer electrolyte membranes can be directly fed by propane gas to make direct propane fuel cell (DPFC). This has many advantages compared to methanol, such as lower cost, greater operating temperature range, easy handling, simpler infrastructure requirements, and higher energy than those of methanol. However, like methanol, DPFC also has the disadvantage that its reaction product is carbon dioxide. 22 refs., 2 tabs., 5 figs.

  11. Direct dry-grinding synthesis of monodisperse lipophilic CuS nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yajuan; Scott, Julie; Chen, Yi-Tzai; Guo, Liangran; Zhao, Mingyang; Wang, Xiaodong [Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, The University of Rhode Island, Kingston, RI 02881 (United States); Lu, Wei, E-mail: weilu@uri.edu [Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, The University of Rhode Island, Kingston, RI 02881 (United States); School of Pharmacy, Fudan University, Shanghai 201203 (China)

    2015-07-15

    Copper sulfide nanoparticles, effective absorbers of near-infrared light, are recently attracting broad interest as a photothermal coupling agent for cancer therapy. Lipophilic copper sulfide nanoparticles are preferred for high performance biomedical applications due to high tissue affinity. Synthesis of lipophilic copper sulfide nanoparticles requires complicated multi-step processes under severe conditions. Here, we describe a new synthetic process, developed by direct dry-grinding of copper(II) acetylacetonate with sulfur under ambient environment at low temperature. The formed CuS nanoparticles are of uniform size, ∼10 nm in diameter, and are monodispersed in chloroform. Each covellite CuS nanocrystal surface is modified with oleylamine through hydrogen bonding between sulfur atoms and amine groups of oleylamine. The nanoparticles demonstrate near-infrared light absorption for photothermal applications. The synthetic methodology described here is more convenient and less extreme than previous methods, and should thus greatly facilitate the preparation of photothermal lipophilic copper sulfide nanomaterials for cancer therapy. - Highlights: • We make lipophilic CuS nanoparticles by mechanical grinding method in large scale. • The reaction condition is studied to obtain high yield and uniform size. • The synthesis does not need nitrogen protection or high temperature. • Lipophilic CuS nanoparticles show significant near-infrared absorbance.

  12. Low Temperature Synthesis of Carbon Nanotubes by Direct Microwave Irradiation

    Science.gov (United States)

    2007-08-09

    Fig. 4(b)). Co9S8, has a spinel structure and it is a microwave absorber. CNTs were successfully synthesized with the cobalt sulfide catalysts...made here is the change of the substrate. We deposited a thin layer of chromium on Teflon substrates, then deposit catalysts. The chromium layer was...Reflected (0W). Chromium adhesion layer was 500 nm. Fig 18. SWNTs synthesized on polymer substrates. (a) and (b) : 5 sec, (c) and (d) : 3 sec

  13. Structure-directing effects of ionic liquids in the ionothermal synthesis of metal–organic frameworks

    Directory of Open Access Journals (Sweden)

    Thomas P. Vaid

    2017-07-01

    Full Text Available Traditional synthesis of metal–organic frameworks (MOFs involves the reaction of a metal-containing precursor with an organic linker in an organic solvent at an elevated temperature, in what is termed a `solvothermal' reaction. More recently, many examples have been reported of MOF synthesis in ionic liquids (ILs, rather than an organic solvent, in `ionothermal' reactions. The high concentration of both cations and anions in an ionic liquid allows for the formation of new MOF structures in which the IL cation or anion or both are incorporated into the MOF. Most commonly, the IL cation is included in the open cavities of the MOF, countering the anionic charge of the MOF framework itself and acting as a template around which the MOF structure forms. Ionic liquids can also serve other structure-directing roles, for example, when an IL containing a single enantiomer of a chiral anion leads to a homochiral MOF, even though the IL anion is not itself incorporated into the MOF. A comprehensive review of ionothermal syntheses of MOFs, and the structure-directing effects of the ILs, is given.

  14. Durability of direct immunofluorescence (DIF) slides stored at room temperature.

    Science.gov (United States)

    Elbendary, Amira; Zhou, Cheng; Truong, Jonathan; Elston, Dirk M

    2015-12-01

    Prior studies suggested that direct immunofluorescence (DIF) slides can be stored at room temperature. We sought to determine the durability of DIF slides stored at room temperature for 5 years. This was a retrospective study of 83 DIF slides archived at room temperature during 2010. The pattern of immunoreactants was compared with those noted in the original report. Loss of reactivity was limited to cases with weak fluorescence at original diagnosis. Loss of IgG was noted in 12.5% of cases, IgA in 12%, C3 in 10%, and IgM in 9.75%. Fibrin showed no loss of reactivity. Preservation of immunofluorescence was not related to site of deposition. Overall, a reliable diagnosis could be made in 75 of 79 archived cases (94.9%). Cases had been archived for periods varying from 4.5 to 5 years. Variations in processing and fluorochromes could affect durability. We have no way of knowing how long slides had been exposed to ultraviolet light at the time of initial examination. DIF showed excellent durability in slides kept at room temperature for 5 years. Copyright © 2015 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.

  15. Directional resolution of head-related transfer functions required in binaural synthesis

    DEFF Research Database (Denmark)

    Minnaar, Pauli; Plogsties, Jan; Christensen, Flemming

    2005-01-01

    In binaural synthesis a virtual sound source is implemented by convolving an anechoic signal with a pair of head-related transfer functions (HRTFs). In order to represent all possible directions of the sound source with respect to the listener a discrete number of HRTFs are measured...... and moving sound sources. A criterion was found that predicts the experimental results. This criterion was used to estimate the directional resolution required in binaural synthesis for all directions on the sphere around the head....

  16. Template-Framework Interactions in Tetraethylammonium-Directed Zeolite Synthesis

    NARCIS (Netherlands)

    Schmidt, Joel E.; Fu, Donglong; Deem, Michael W.; Weckhuysen, Bert M.

    2016-01-01

    Zeolites, having widespread applications in chemical industries, are often synthesized using organic templates. These can be cost-prohibitive, motivating investigations into their role in promoting crystallization. Herein, the relationship between framework structure, chemical composition, synthesis

  17. Investigation of Fundamental Properties of Catalysts for Direct and Indirect Synthesis of DME

    OpenAIRE

    Risa, Kamilla Opheim

    2014-01-01

    Dimethyl ether (DME) has potential as an environmentally friendly fuel. The main advantage of DME as a fuel lies in its clean combustion; the emissions of soot and particulate matter, as well as NOx and SOx are significantly reduced compared to emissions from diesel combustion. DME is produced in a two-step process today, where methanol synthesis is followed by methanol dehydration. The production of DME directly from synthesis gas represents a more thermodynamically favorable synthesis route...

  18. Direct chemical vapour deposited grapheme synthesis on silicon oxide by controlled copper dewettting

    NARCIS (Netherlands)

    van den Beld, Wesley Theodorus Eduardus; van den Berg, Albert; Eijkel, Jan C.T.

    2015-01-01

    In this paper we present a novel method for direct uniform graphene synthesis onto silicon oxide in a controlled manner. On a grooved silicon oxide wafer is copper deposited under a slight angle and subsequently the substrate is treated by a typical graphene synthesis process. During this process

  19. The use of plasma processing for catalyst and membrane synthesis and direct production of hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Brault, P.; Thomann, A.L.; Cormier, J.M.; Lefaucheux, Ph. [Orleans Univ., Groupe de Recheches sur l' Energetique des Milieux Ionises, UMR 6606, 45 (France)

    2000-07-01

    Plasma technologies are introduced in the field of hydrogen synthesis related to fuel cells. Two ways are described: plasma synthesis of catalysts and membranes for the production and separation of hydrogen and direct production of hydrogen based on atmospheric plasma assisted methane steam reforming.

  20. Differential chromosomal and mitochondrial DNA synthesis in temperature-sensitive mutants of Ustilago maydis

    Energy Technology Data Exchange (ETDEWEB)

    Unrau, P.

    1977-01-01

    The amount and type of residual DNA synthesis was determined in eight temperature-sensitive mutants of the smut fungus Ustilago maydis after incubation at the restrictive temperature (32/sup 0/C) for eight hours. Mutants ts-220, ts-207, ts-432 and ts-346 were found to have an overall reduction in the synthesis of both nuclear and mitochondrial DNA in comparison to the wild-type. In mutants ts-20, tsd 1-1, ts-84 and pol 1-1 nuclear DNA synthesis was depressed relative to mitochondrial synthesis. The DNA-polymerase mutant pol 1-1 had persistent nuclear synthesis at about 50% of the rate of synthesis of mitochondrial DNA and similar behavior was observed in a diploid homozygous strain. Mutant ts-84 had an initial burst of DNA synthesis which was reduced for nuclear but not mitochondrial synthesis after three hours preincubation at 32/sup 0/C. tsd 1-1 and ts-20 had nuclear residual synthesis amounting to about 25% of the relative rate of mitochondrial synthesis which correlates to increasing UV sensitivity of these strains on incubation at 32/sup 0/C. A pol 1-1 ts-84 double mutant had an additive loss of nuclear DNA synthesis which indicates that the steps of replication involved may be sequential.

  1. Direct Energy Supply to the Reaction Mixture during Microwave-Assisted Hydrothermal and Combustion Synthesis of Inorganic Materials

    Directory of Open Access Journals (Sweden)

    Roberto Rosa

    2014-05-01

    Full Text Available The use of microwaves to perform inorganic synthesis allows the direct transfer of electromagnetic energy inside the reaction mixture, independently of the temperature manifested therein. The conversion of microwave (MW radiation into heat is useful in overcoming the activation energy barriers associated with chemical transformations, but the use of microwaves can be further extended to higher temperatures, thus creating unusual high-energy environments. In devising synthetic methodologies to engineered nanomaterials, hydrothermal synthesis and solution combustion synthesis can be used as reference systems to illustrate effects related to microwave irradiation. In the first case, energy is transferred to the entire reaction volume, causing a homogeneous temperature rise within a closed vessel in a few minutes, hence assuring uniform crystal growth at the nanometer scale. In the second case, strong exothermic combustion syntheses can benefit from the application of microwaves to convey energy to the reaction not only during the ignition step, but also while it is occurring and even after its completion. In both approaches, however, the direct interaction of microwaves with the reaction mixture can lead to practically gradient-less heating profiles, on the basis of which the main observed characteristics and properties of the aforementioned reactions and products can be explained.

  2. Scalable Self-Propagating High-Temperature Synthesis of Graphene for Supercapacitors with Superior Power Density and Cyclic Stability.

    Science.gov (United States)

    Li, Chen; Zhang, Xiong; Wang, Kai; Sun, Xianzhong; Liu, Guanghua; Li, Jiangtao; Tian, Huanfang; Li, Jianqi; Ma, Yanwei

    2017-02-01

    An ultrafast self-propagating high-temperature synthesis technique offers scalable routes for the fabrication of mesoporous graphene directly from CO2 . Due to the excellent electrical conductivity and high ion-accessible surface area, supercapacitor electrodes based on the obtained graphene exhibit superior energy and power performance. The capacitance retention is higher than 90% after one million charge/discharge cycles. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Self-propagating high-temperature synthesis (SHS) and microwave-assisted combustion synthesis (MACS) of the thallium superconducting phases

    Science.gov (United States)

    Bayya, S. S.; Snyder, R. L.

    1994-05-01

    This paper explores the speed of reaction as a parameter to minimizing thallium loss. Self-propagating high-temperature synthesis (SHS) and microwave-assisted combustion synthesis (MACS) were developed for the synthesis of Tl-2212 and Tl-2223 superconductors using Cu metal powder as a fuel. A kitchen microwave oven was used to carry out MACS reactions. The samples were reacted for few seconds and led to the formation of the superconducting phases. Further explorations and modifications in the processing could lead to the formation of single phases by MACS.

  4. Silver-palladium catalysts for the direct synthesis of hydrogen peroxide

    Science.gov (United States)

    Khan, Zainab; Dummer, Nicholas F.; Edwards, Jennifer K.

    2017-11-01

    A series of bimetallic silver-palladium catalysts supported on titania were prepared by wet impregnation and assessed for the direct synthesis of hydrogen peroxide, and its subsequent side reactions. The addition of silver to a palladium catalyst was found to significantly decrease hydrogen peroxide productivity and hydrogenation, but crucially increase the rate of decomposition. The decomposition product, which is predominantly hydroxyl radicals, can be used to decrease bacterial colonies. The interaction between silver and palladium was characterized using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (TPR). The results of the TPR and XPS indicated the formation of a silver-palladium alloy. The optimal 1% Ag-4% Pd/TiO2 bimetallic catalyst was able to produce approximately 200 ppm of H2O2 in 30 min. The findings demonstrate that AgPd/TiO2 catalysts are active for the synthesis of hydrogen peroxide and its subsequent decomposition to reactive oxygen species. The catalysts are promising for use in wastewater treatment as they combine the disinfectant properties of silver, hydrogen peroxide production and subsequent decomposition. This article is part of a discussion meeting issue 'Providing sustainable catalytic solutions for a rapidly changing world'.

  5. Rapid and direct synthesis of complex perovskite oxides through a highly energetic planetary milling

    Science.gov (United States)

    Lee, Gyoung-Ja; Park, Eun-Kwang; Yang, Sun-A.; Park, Jin-Ju; Bu, Sang-Don; Lee, Min-Ku

    2017-04-01

    The search for a new and facile synthetic route that is simple, economical and environmentally safe is one of the most challenging issues related to the synthesis of functional complex oxides. Herein, we report the expeditious synthesis of single-phase perovskite oxides by a high-rate mechanochemical reaction, which is generally difficult through conventional milling methods. With the help of a highly energetic planetary ball mill, lead-free piezoelectric perovskite oxides of (Bi, Na)TiO3, (K, Na)NbO3 and their modified complex compositions were directly synthesized with low contamination. The reaction time necessary to fully convert the micron-sized reactant powder mixture into a single-phase perovskite structure was markedly short at only 30-40 min regardless of the chemical composition. The cumulative kinetic energy required to overtake the activation period necessary for predominant formation of perovskite products was ca. 387 kJ/g for (Bi, Na)TiO3 and ca. 580 kJ/g for (K, Na)NbO3. The mechanochemically derived powders, when sintered, showed piezoelectric performance capabilities comparable to those of powders obtained by conventional solid-state reaction processes. The observed mechanochemical synthetic route may lead to the realization of a rapid, one-step preparation method by which to create other promising functional oxides without time-consuming homogenization and high-temperature calcination powder procedures.

  6. Direct Synthesis of Fe-Pt Nanoparticles in Ordered Face Centered (fct) LIo Phase by Microwave Assisted Route

    Science.gov (United States)

    Acharya, S. A.; Khule, S. M.; Singh, K.; Bhoga, S. S.

    2011-07-01

    In the present work, microwave-assisted chemical reduction route has been explored for the direct synthesis of fct LIo-phase of Fe-Pt nanoparticles. Effects of microwave power and irradiation time on the growth process were investigated. Using this facile and high yield technique we could tune particle size from 7 to 17 nm. The as-prepared FePt were found to be sensitive to the microwave irradiation power, while influence of exposure time was insignificant. The hysteresis measurements were performed at room temperature (300 K) to study magnetic properties of as-synthesized Fe-Pt as a function of crystallize size. The coercivity and saturation magnetization was observed to be decrease with diminishing for direct synthesis of metal alloys.

  7. Direct and Versatile Synthesis of Red-Shifted Azobenzenes

    NARCIS (Netherlands)

    Hansen, Mickel J.; Lerch, Michael M.; Szymanski, Wiktor; Feringa, Ben L.

    2016-01-01

    A straightforward synthesis of azobenzenes with bathochromically-shifted absorption bands is presented. It employs an ortho-lithiation of aromatic substrates, followed by a coupling reaction with aryldiazonium salts. The products are obtained with good to excellent yields after simple purification.

  8. Direct synthesis of metal nanoparticles with tunable porosity

    NARCIS (Netherlands)

    Detsi, Eric; Punzhin, Sergey; Onck, Patrick R.; De Hosson, Jeff Th. M.

    2012-01-01

    Herein, we report a facile one-step synthesis route of porous bimetallic Au-Ag nanoparticles involving two parallel processes: alloying during nanocrystal growth and dealloying via galvanic replacement reaction. Further, we show that porosity in these nanoparticles can be tuned via their alloy

  9. Nickel-catalyzed direct synthesis of dialkoxymethane ethers

    Indian Academy of Sciences (India)

    MURUGAN SUBARAMANIAN

    and the inhibitor of HIV-1 Integrase (IN), etc.10,11. The use of dialkoxymethane as reagents for the N- alkoxymethylation of secondary amides in the pres- ence of Lewis acids12 and Brønsted acids13 has also been reported. Given their importance, the develop- ment of efficient, benign strategies for the synthesis of.

  10. Nuclear transport factor directs localization of protein synthesis during mitosis

    NARCIS (Netherlands)

    Bogaart, Geert van den; Meinema, Anne C.; Krasnikov, Viktor; Veenhoff, Liesbeth M.; Poolman, Bert

    Export of messenger RNA from the transcription site in the nucleus and mRNA targeting to the translation site in the cytoplasm are key regulatory processes in protein synthesis. In yeast, the mRNA-binding proteins Nab2p and Nab4p/Hrp1p accompany transcripts to their translation site, where the

  11. Self-sustained high-temperature reactions : Initiation, propagation and synthesis

    NARCIS (Netherlands)

    Martinez Pacheco, M.

    2007-01-01

    Self-Propagating High-Temperature Synthesis (SHS), also called combustion synthesis is an exothermic and self-sustained reaction between the constituents, which has assumed significance for the production of ceramics and ceramic-metallic materials (cermets), because it is a very rapid processing

  12. Low temperature solution synthesis of zinc antimonide, manganese antimonide, and strontium ruthenate compounds

    Science.gov (United States)

    Noblitt, Jennifer Lenkner

    2011-12-01

    Increasing energy demands are fueling research in the area of renewable energy and energy storage. In particular, Li-ion batteries and superconducting wires are attractive choices for energy storage. Improving safety, simplifying manufacturing processes, and advancing technology to increase energy storage capacity is necessary to compete with current marketed energy storage devices. These advancements are accomplished through the study of new materials and new morphologies. Increasing dependence on and rising demand for portable electronic devices has continued to drive research in the area of Li-ion batteries. In order to compete with existing batteries and be applicable to future energy needs such as powering hybrid vehicles, the drawbacks of Li-ion batteries must be addressed including (i) low power density, (ii) safety, and (iii) high manufacturing costs. These drawbacks can be addressed through new materials and morphologies for the anode, cathode, and electrolyte. New intermetallic anode materials such as ZnSb, MnSb, and Mn2Sb are attractive candidates to replace graphite, the current industry standard anode material, because they are safer while maintaining comparable theoretical capacity. Electrodeposition is an inexpensive method that could be used for the synthesis of these electrode materials. Direct electrodeposition allows for excellent electrical contact to the current collector without the use of a binder. To successfully electrodeposit zinc and manganese antimonides, metal precursors with excellent solubility in water were needed. To promote solubility, particularly for the antimony precursor, coordinating ligands were added to the deposition bath solutions. This work shows that the choice of coordinating ligand and metal-ligand speciation can alter both the electrochemistry and the film composition. This work focuses on the search for appropriate coordinating ligands, solution pH, and bath temperatures so that high quality films of ZnSb, MnSb, and

  13. Direct Synthesis of ESBO Derivatives-18O Labelled with Dioxirane

    Directory of Open Access Journals (Sweden)

    Stefano La Tegola

    2013-01-01

    Full Text Available This work addresses a new approach developed in our laboratory, consisting in the application of isolated dimethyldioxirane (DDO, 1a labelled with 18O for synthesis of epoxidized glyceryl linoleate (Gly-LLL, 2. We expect that this work could contribute in improving analytical methods for the determination of epoxidized soybean oil (ESBO in complex food matrices by adopting an 18O-labelled-epoxidized triacylglycerol as an internal standard.

  14. Template directed synthesis of highly organized functional biomimetic silica nanostructures

    OpenAIRE

    Kind, Lucy

    2009-01-01

    Silica is an important mineral in technological and biological applications. Many protocols have been developed for the synthesis of complex silica architectures. Most prominent is the silicification approach, where polymers build up the templates for the revealed polymer/silica structures. The current thesis demonstrates that star-shaped polymers and block copolymers are efficient templates for the fabrication of silica particles with spherical or raspberry-like morphology....

  15. ɛ-Iron carbide as a low-temperature Fischer-Tropsch synthesis catalyst

    Science.gov (United States)

    Xu, Ke; Sun, Bo; Lin, Jun; Wen, Wen; Pei, Yan; Yan, Shirun; Qiao, Minghua; Zhang, Xiaoxin; Zong, Baoning

    2014-12-01

    ɛ-Iron carbide has been predicted to be promising for low-temperature Fischer-Tropsch synthesis (LTFTS) targeting liquid fuel production. However, directional carbidation of metallic iron to ɛ-iron carbide is challenging due to kinetic hindrance. Here we show how rapidly quenched skeletal iron featuring nanocrystalline dimensions, low coordination number and an expanded lattice may solve this problem. We find that the carbidation of rapidly quenched skeletal iron occurs readily in situ during LTFTS at 423-473 K, giving an ɛ-iron carbide-dominant catalyst that exhibits superior activity to literature iron and cobalt catalysts, and comparable to more expensive noble ruthenium catalyst, coupled with high selectivity to liquid fuels and robustness without the aid of electronic or structural promoters. This finding may permit the development of an advanced energy-efficient and clean fuel-oriented FTS process on the basis of a cost-effective iron catalyst.

  16. ε-Iron carbide as a low-temperature Fischer-Tropsch synthesis catalyst.

    Science.gov (United States)

    Xu, Ke; Sun, Bo; Lin, Jun; Wen, Wen; Pei, Yan; Yan, Shirun; Qiao, Minghua; Zhang, Xiaoxin; Zong, Baoning

    2014-12-12

    ε-Iron carbide has been predicted to be promising for low-temperature Fischer-Tropsch synthesis (LTFTS) targeting liquid fuel production. However, directional carbidation of metallic iron to ε-iron carbide is challenging due to kinetic hindrance. Here we show how rapidly quenched skeletal iron featuring nanocrystalline dimensions, low coordination number and an expanded lattice may solve this problem. We find that the carbidation of rapidly quenched skeletal iron occurs readily in situ during LTFTS at 423-473 K, giving an ε-iron carbide-dominant catalyst that exhibits superior activity to literature iron and cobalt catalysts, and comparable to more expensive noble ruthenium catalyst, coupled with high selectivity to liquid fuels and robustness without the aid of electronic or structural promoters. This finding may permit the development of an advanced energy-efficient and clean fuel-oriented FTS process on the basis of a cost-effective iron catalyst.

  17. Multiplexed Sensor for Synthesis Gas Compsition and Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Steven Buckley; Reza Gharavi; Marco Leon

    2007-10-01

    The overall goal of this project has been to develop a highly sensitive, multiplexed TDL-based sensor for CO{sub 2}, CO, H{sub 2}O (and temperature), CH{sub 4}, H{sub 2}S, and NH{sub 3}. Such a sensor was designed with so-called 'plug-and-play' characteristics to accommodate additional sensors, and provided in situ path-integrated measurements indicative of average concentrations at speeds suitable for direct gasifier control. The project developed the sensor and culminated in a real-world test of the underlying technology behind the sensor. During the project, new underlying measurements of spectroscopic constants for all of the gases of interest performed, in custom cells built for the project. The envisioned instrument was built from scratch from component lasers, fiber optics, amplifier blocks, detectors, etc. The sensor was tested for nearly a week in an operational power plant. The products of this research are expected to have a direct impact on gasifier technology and the production of high-quality syngas, with substantial broader application to coal and other energy systems. This report is the final technical report on project DE-FG26-04NT42172. During the project we completed all of the milestones planned in the project, with a modification of milestone (7) required due to lack of funding and personnel.

  18. Self-propagating high temperature synthesis and magnetic ...

    Indian Academy of Sciences (India)

    Unknown

    , microstructure and magnetic properties of the combustion products. The effect of ... productivity, low external energy consumption, short synthesis time, simple facility and high quality of the products. Although there have been many attempts to.

  19. Hydrothermal synthesis of zeolite T from kaolin using two different structure-directing agents

    Science.gov (United States)

    E Arshad, Sazmal; Lutfor Rahman, M.; Sarkar, Shaheen M.; Yusslee, Eddy F.; Patuwan, Siti Z.

    2018-01-01

    Zeolite T was synthesized from the molar chemical composition of 1SiO2:0.04Al2O3:0.26Na2O:0.09K2O:14H2O in the form of a homogenous milky solution in the presence of the two different structure-directing agents TMAOH and TEAOH respectively. Modification of the composition of silica was undertaken using metakaolin from calcined kaolin at 750 °C for 4 h, while the molar composition of each different SDA was variated from 0.05, 0.10, 0.15, 0.20 and 0.25. The homogenous mixture was left at room temperature for 24 h before undergoing hydrothermal synthesis at 100 °C for 168 h. The synthesized samples were filtered and aged at 120 °C for 2 h and each sample was calcined at high temperatures (545 °C for TMAOH and 520 °C for TEAOH) for template removal before characterization using XRD and SEM. Crystallization of the zeolite T in its major form only took place at a molar ratio of 0.10 of TMAOH, while TEAOH showed the species evolution of zeolite T into zeolite L and W for other molar ratios.

  20. Scale study of direct synthesis of dimethyl ether from biomass synthesis gas.

    Science.gov (United States)

    Lv, Yongxing; Wang, Tiejun; Wu, Chuangzhi; Ma, Longlong; Zhou, Yi

    2009-01-01

    We investigated the synthesis of dimethyl ether (DME) from biomass synthesis gas using a kind of hybrid catalyst consisting of methanol and HZSM-5 zeolite in a fixed-bed reactor in a 100 ton/year pilot plant. The biomass synthesis gas was produced by oxygen-rich gasification of corn core in a two-stage fixed bed. The results showed that CO conversions reached 82.00% and 73.55%, the selectivities for DME were 73.95% and 69.73%, and the space-time yields were 124.28 kg m(-3) h(-1) and 203.80 kg m(-3) h(-1) when gas hourly space velocities were 650 h(-1) and 1200 h(-1), respectively. Deoxidation and tar removal from biomass synthesis gas was critical to the stable operation of the DME synthesis system. Using single-pass synthesis, the H(2)/CO ratio improved from 0.98-1.17 to 2.12-2.22. The yield of DME would be increased greatly if the exhaust was reused after removal of the CO(2).

  1. Direct and Versatile Synthesis of Red-Shifted Azobenzenes.

    Science.gov (United States)

    Hansen, Mickel J; Lerch, Michael M; Szymanski, Wiktor; Feringa, Ben L

    2016-10-17

    A straightforward synthesis of azobenzenes with bathochromically-shifted absorption bands is presented. It employs an ortho-lithiation of aromatic substrates, followed by a coupling reaction with aryldiazonium salts. The products are obtained with good to excellent yields after simple purification. Moreover, with the presented methodology, a structurally diverse panel of different azobenzenes, including unsymmetric tetra-ortho-substituted ones, can be readily obtained, which paves the way for future development of red-light-addressable azobenzene derivatives for in vivo application. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. 21 CFR 882.1570 - Powered direct-contact temperature measurement device.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Powered direct-contact temperature measurement....1570 Powered direct-contact temperature measurement device. (a) Identification. A powered direct-contact temperature measurement device is a device which contains a power source and is used to measure...

  3. Ferrous sulfate based low temperature synthesis and magnetic properties of nickel ferrite nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Tejabhiram, Y., E-mail: tejabhiram@gmail.com [Nanotechnology Research Center, SRM University, SRM Nagar, Kattankulathur, Kancheepuram District, TN 603203 (India); Pradeep, R. [Department of Physics and Nanotechnology, SRM University, SRM Nagar, Kattankulathur, Kancheepuram District, TN 603203 (India); Helen, A.T.; Gopalakrishnan, C. [Nanotechnology Research Center, SRM University, SRM Nagar, Kattankulathur, Kancheepuram District, TN 603203 (India); Ramasamy, C. [Department of Pharmacy Practice, SRM University, SRM Nagar, Kattankulathur, Kancheepuram District, TN 603203 (India)

    2014-12-15

    Highlights: • Novel low temperature synthesis of nickel ferrite nanoparticles. • Comparison with two conventional synthesis techniques including hydrothermal method. • XRD results confirm the formation of crystalline nickel ferrites at 110 °C. • Superparamagnetic particles with applications in drug delivery and hyperthermia. • Magnetic properties superior to conventional methods found in new process. - Abstract: We report a simple, low temperature and surfactant free co-precipitation method for the preparation of nickel ferrite nanostructures using ferrous sulfate as the iron precursor. The products obtained from this method were compared for their physical properties with nickel ferrites produced through conventional co-precipitation and hydrothermal methods which used ferric nitrate as the iron precursor. X-ray diffraction analysis confirmed the synthesis of single phase inverse spinel nanocrystalline nickel ferrites at temperature as low as 110 °C in the low temperature method. Electron microscopy analysis on the samples revealed the formation of nearly spherical nanostructures in the size range of 20–30 nm which are comparable to other conventional methods. Vibrating sample magnetometer measurements showed the formation of superparamagnetic particles with high magnetic saturation 41.3 emu/g which corresponds well with conventional synthesis methods. The spontaneous synthesis of the nickel ferrite nanoparticles by the low temperature synthesis method was attributed to the presence of 0.808 kJ mol{sup −1} of excess Gibbs free energy due to ferrous sulfate precursor.

  4. Concise enantioselective synthesis of duloxetine via direct catalytic asymmetric aldol reaction of thioamide.

    Science.gov (United States)

    Suzuki, Yuta; Iwata, Mitsutaka; Yazaki, Ryo; Kumagai, Naoya; Shibasaki, Masakatsu

    2012-05-04

    Direct catalytic asymmetric aldol reaction of thioamide offers a new entry to the concise enantioselective synthesis of duloxetine. The direct aldol protocol was scalable (>20 g) to afford the aldol product in 92% ee after LiAlH(4) reduction, and 84% of the chiral ligand was recovered after recrystallization. The following four steps of transformation delivered duloxetine.

  5. Modified ambient template-directed synthesis, characterization and applications of one-dimensional nanomaterials

    Science.gov (United States)

    Zhang, Fen

    2009-12-01

    Nanomaterials have attracted considerable attention due to their unique physical properties and potential applications as building blocks in nanoscale devices. In particular, the intrinsic anisotropy inherent in one-dimensional (1D) nanomaterials renders them the smallest dimension structures that can be utilized for the efficient transport of electron and optical excitation. The template-directed synthesis technique represents the most straightforward and versatile route for achieving 1D growth. However, there are still challenges including (1) the development of an environmentally-friendly synthetic method, (2) a deep understanding of the relationship between size, composition, and physical properties in 1D nanostructures, (3) the design of 1D nanomaterials with novel properties, and (4) the application of 1D nanostructures in various fields, such as energy, catalysis, and biotechnology. Hence, the synthesis and characterization of 1D nanostructures, as well as the complementary study of the novel properties and potential applications of the resulting nanomaterials have been the focal points of my graduate study. Specifically, a modified template-directed technique has been developed, using a double-diffusion setup via a biomimetic crystallization process, which has enabled the successful preparation of various single-crystalline 1D nanostructures, including fluorides, tungstates, sulfides, and phosphates, under ambient, room-temperature conditions, without using either very harmful precursors or solvents, and without generating particularly toxic byproducts. The family of alkaline-earth metal binary and perovskite ternary fluoride nanowires, doped with rare-earth ions, has displayed unique luminescence properties, with applications in optical devices. In addition, the generation of tungstate solid solution 1D nanostructures provides for a fundamental understanding of composition-modulated luminescence properties, leading to key structure-property correlations. A

  6. Direct synthesis of nanocrystalline oxide powders by wet-chemical techniques

    Directory of Open Access Journals (Sweden)

    Vladimir V. Srdić

    2010-09-01

    Full Text Available In a recent period there is a great need for increasing the knowledge of tailoring the innovative procedures for the synthesis of electroceramic nanopowders and materials with improved quality for specific application. In order to produce electroceramics with desirable microstructure and properties, synthesis of stoichiometric, ultra-fine and agglomerate free powders with narrow size distributions is one of the most important steps. Within this scope, in the present paper we summarize our recent results on direct synthesis of some important perovskites and ferrites nanopowders by wet-chemical techniques.

  7. Low temperature synthesis of nanocrystalline scandia-stabilized ...

    Indian Academy of Sciences (India)

    Zirconia stabilized with 11 mol% scandia (11ScSZ) has been successfully synthesized by novel alanine-assisted soft chemical aqueous combustion method. The reaction kinetics during combustion synthesis has been studied in detail by analysing thermal behaviour of different metal–alanine complexes. A single phase ...

  8. Behavioral Synthesis of Asynchronous Circuits Using Syntax Directed Translation as Backend

    DEFF Research Database (Denmark)

    Nielsen, Sune Fallgaard; Sparsø, Jens; Madsen, Jan

    2009-01-01

    The current state-of-the art in high-level synthesis of asynchronous circuits is syntax directed translation, which performs a one-to-one mapping of a HDL-description into a corresponding circuit. This paper presents a method for behavioral synthesis of asynchronous circuits which builds on top...... of syntax directed translation, and which allows the designer to perform automatic design space exploration guided by area or speed constraints. The paper presents an asynchronous implementation template consisting of a data-path and a control unit and its implementation using the asynchronous hardware...

  9. A decade of adaptive governance scholarship: synthesis and future directions

    Directory of Open Access Journals (Sweden)

    Brian C. Chaffin

    2014-09-01

    Full Text Available Adaptive governance is an emergent form of environmental governance that is increasingly called upon by scholars and practitioners to coordinate resource management regimes in the face of the complexity and uncertainty associated with rapid environmental change. Although the term "adaptive governance" is not exclusively applied to the governance of social-ecological systems, related research represents a significant outgrowth of literature on resilience, social-ecological systems, and environmental governance. We present a chronology of major scholarship on adaptive governance, synthesizing efforts to define the concept and identifying the array of governance concepts associated with transformation toward adaptive governance. Based on this synthesis, we define adaptive governance as a range of interactions between actors, networks, organizations, and institutions emerging in pursuit of a desired state for social-ecological systems. In addition, we identify and discuss ambiguities in adaptive governance scholarship such as the roles of adaptive management, crisis, and a desired state for governance of social-ecological systems. Finally, we outline a research agenda to examine whether an adaptive governance approach can become institutionalized under current legal frameworks and political contexts. We suggest a further investigation of the relationship between adaptive governance and the principles of good governance; the roles of power and politics in the emergence of adaptive governance; and potential interventions such as legal reform that may catalyze or enhance governance adaptations or transformation toward adaptive governance.

  10. Numerical investigation of high temperature synthesis gas premixed combustion via ANSYS Fluent

    OpenAIRE

    Pashchenko Dmitry

    2018-01-01

    A numerical model of the synthesis gas pre-mixed combustion is developed. The research was carried out via ANSYS Fluent software. Verification of the numerical results was carried out using experimental data. A visual comparison of the flame contours that obtained by the synthesis gas combustion for Re = 600; 800; 1000 was performed. A comparison of the wall temperature of the combustion chamber, obtained with the help of the developed model, with the results of a physical experiment was also...

  11. The electrolyte challenge for a direct methanol-air polymer electrolyte fuel cell operating at temperatures up to 200 C

    Science.gov (United States)

    Savinell, Robert; Yeager, Ernest; Tryk, Donald; Landau, Uziel; Wainright, Jesse; Gervasio, Dominic; Cahan, Boris; Litt, Morton; Rogers, Charles; Scherson, Daniel

    1993-01-01

    Novel polymer electrolytes are being evaluated for use in a direct methanol-air fuel cell operating at temperatures in excess of 100 C. The evaluation includes tests of thermal stability, ionic conductivity, and vapor transport characteristics. The preliminary results obtained to date indicate that a high temperature polymer electrolyte fuel cell is feasible. For example, Nafion 117 when equilibrated with phosphoric acid has a conductivity of at least 0.4 Omega(exp -1)cm(exp -1) at temperatures up to 200 C in the presence of 400 torr of water vapor and methanol vapor cross over equivalent to 1 mA/cm(exp 2) under a one atmosphere methanol pressure differential at 135 C. Novel polymers are also showing similar encouraging results. The flexibility to modify and optimize the properties by custom synthesis of these novel polymers presents an exciting opportunity to develop an efficient and compact methanol fuel cell.

  12. Selective anaerobic oxidation of methane enables direct synthesis of methanol.

    Science.gov (United States)

    Sushkevich, Vitaly L; Palagin, Dennis; Ranocchiari, Marco; van Bokhoven, Jeroen A

    2017-05-05

    Direct functionalization of methane in natural gas remains a key challenge. We present a direct stepwise method for converting methane into methanol with high selectivity (~97%) over a copper-containing zeolite, based on partial oxidation with water. The activation in helium at 673 kelvin (K), followed by consecutive catalyst exposures to 7 bars of methane and then water at 473 K, consistently produced 0.204 mole of CH 3 OH per mole of copper in zeolite. Isotopic labeling confirmed water as the source of oxygen to regenerate the zeolite active centers and renders methanol desorption energetically favorable. On the basis of in situ x-ray absorption spectroscopy, infrared spectroscopy, and density functional theory calculations, we propose a mechanism involving methane oxidation at Cu II oxide active centers, followed by Cu I reoxidation by water with concurrent formation of hydrogen. Copyright © 2017, American Association for the Advancement of Science.

  13. Phenotypical temperature adaptation of protein synthesis in wheat seedlings: time curves for readaptation.

    Science.gov (United States)

    Weidner, M; Combrink, G

    1979-07-01

    Optimum temperature and temperature coefficient of protein synthesis in young wheat plants exhibit phenotypical temperature adaptation. In plants grown for 2 days at either chilling (4 C), medium (20 C), or high (36 C) temperature the respective values are: 27 C and 14.2 kilocalories per mole, 31 C and 18.2 kilocalories per mole, 35 C and 23.6 kilocalories per mole, based on in vivo [(14)C]leucine incorporation into total protein. The validity of the [(14)C]leucine incubation method has been confirmed by double-labeling experiments. Readaptation time curves are complex: the optimum temperature parameter readjusts within approximately 4 hours to an altered temperature regime, whereas the temperature coefficient needs between 4 and 96 hours for complete readaptation-depending on the temperature conditions prior to the temperature shift. Heat-preadapted plants need a recovery period at medium temperature to regain their cold adaptability with respect to optimum temperature. Cycloheximide (30 micrograms per milliliter) reduces [(14)C]leucine incorporation into protein by 85%, thus indicating that predominantly the cytoplasmic 80S system of protein synthesis is involved in temperature adaptation.

  14. Modelling of flame temperature of solution combustion synthesis of ...

    Indian Academy of Sciences (India)

    A regression model has also been developed to correlate the input parameters, viz. batch size, diluents, fuel to oxidizer ratio and initial furnace temperature, with flame temperature of the solution combustion reaction. The adequacy of the developed model has been checked using analysis of variance technique.

  15. Synthesis and characterization of Al-TON zeolite using a dialkylimizadolium as structure-directing agent

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, Christian Wittee; Pergher, Sibele Berenice Castella, E-mail: chriswittee@gmail.com [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil); Villarroel-Rocha, Jhonny [Laboratorio de Solidos Porosos, Instituto de Fisica Aplicada, Universidad Nacional de San Luis, Chacabuco, San Luis (Argentina); Silva, Bernardo Araldi Da; Mignoni, Marcelo Luis [Universidade Regional Integrada, Erechim, RS (Brazil)

    2016-11-15

    In this work, the synthesis of zeolites using 1-butyl-3-methylimidazolium chloride [C{sub 4}MI]Cl as a structure-directing agent was investigated. The organic cation shows effectiveness and selectivity for the syntheses of TON zeolites under different reaction conditions compared to the traditional structure directing agent, 1,8-diaminooctane. The 1-butyl-3-methylimidazolium cation lead to highly crystalline materials and its role as OSDA in our synthesis conditions has been confirmed by characterization techniques. ICP-OES confirms the presence of Al in the samples and {sup 27}Al MAS NMR analysis indicated that aluminum atoms were incorporated in tetrahedral coordination. Scanning electron microscopy indicated that changing the crystallization condition (static or stirring), zeolites with different crystal size were obtained, which consequently affects the textural properties of the zeolites. Moreover, varying some synthesis parameters MFI zeolite can also be obtained. (author)

  16. Direct Synthesis of Telechelic Polyethylene by Selective Insertion Polymerization

    KAUST Repository

    Jian, Zhongbao

    2016-10-14

    A single-step route to telechelic polyethylene (PE) is enabled by selective insertion polymerization. PdII-catalyzed copolymerization of ethylene and 2-vinylfuran (VF) generates α,ω-di-furan telechelic polyethylene. Orthogonally reactive exclusively in-chain anhydride groups are formed by terpolymerization with carbic anhydride. Combined experimental and theoretical DFT studies reveal the key for this direct approach to telechelics to be a match of the comonomers’ different electronics and bulk. Identified essential features of the comonomer are that it is an electron-rich olefin that forms an insertion product stabilized by an additional interaction, namely a π–η3 interaction for the case of VF.

  17. Synthesis of a specified, silica molecular sieve by using computationally predicted organic structure-directing agents.

    Science.gov (United States)

    Schmidt, Joel E; Deem, Michael W; Davis, Mark E

    2014-08-04

    Crystalline molecular sieves are used in numerous applications, where the properties exploited for each technology are the direct consequence of structural features. New materials are typically discovered by trial and error, and in many cases, organic structure-directing agents (OSDAs) are used to direct their formation. Here, we report the first successful synthesis of a specified molecular sieve through the use of an OSDA that was predicted from a recently developed computational method that constructs chemically synthesizable OSDAs. Pentamethylimidazolium is computationally predicted to have the largest stabilization energy in the STW framework, and is experimentally shown to strongly direct the synthesis of pure-silica STW. Other OSDAs with lower stabilization energies did not form STW. The general method demonstrated here to create STW may lead to new, simpler OSDAs for existing frameworks and provide a way to predict OSDAs for desired, theoretical frameworks. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. The synthesis of aluminophosphate and germanosilicate LTA using a triquaternary structure directing agent

    OpenAIRE

    Schmidt, Joel E.; Zones, Stacey I.; Xie, Dan; Davis, Mark E.

    2014-01-01

    The use of triquaternary organic structure directing agents (OSDAs) for the synthesis of microporous materials is relatively unexplored. Here a triquaternary OSDA prepared by reacting 1,2-dimethylimidazole with 1,3,5-tris(bromomethyl)benzene promotes the formation of LTA in the aluminophosphate or germanosilicate reaction chemistries.

  19. Direct synthesis of dimethyl carbonate from CO 2 and methanol over ...

    Indian Academy of Sciences (India)

    The direct synthesis of dimethyl carbonate (DMC) from carbon dioxide CO2 and methanol is an attractive approach towards conversion of the greenhouse gas - CO2 into value-added chemicals and fuels.Ceria CeO2 catalyzes this reaction. But the conversion efficiency of CeO2 is enhanced when the byproductwater in the ...

  20. The synthesis of sterically hindered amines by a direct reductive amination of ketones.

    Science.gov (United States)

    Yagafarov, Niyaz Z; Kolesnikov, Pavel N; Usanov, Dmitry L; Novikov, Valentin V; Nelyubina, Yulia V; Chusov, Denis

    2016-01-25

    An atom-economical methodology for the synthesis of sterically hindered tertiary amines was developed, which is based on complementary Rh- and Ru-catalyzed direct reductive amination of ketones with primary and secondary amines using carbon monoxide as a deoxygenating agent.

  1. Depression of leukocyte protein synthesis, immune function and growth performance induced by high environmental temperature in broiler chickens

    Science.gov (United States)

    Kamel, Nancy N.; Ahmed, Ayman M. H.; Mehaisen, Gamal M. K.; Mashaly, Magdi M.; Abass, Ahmed O.

    2017-09-01

    In tropical and semitropical regions, raising broiler chickens out of their thermal comfort zone can cause an added economic loss in the poultry industry. The cause for the deleterious effects on immunity and growth performance of broilers under high environmental temperatures is still poorly understood. Therefore, the aim of the current investigation was to evaluate the effect of heat stress on leukocytes protein synthesis and immune function as a possible direct cause of low performance in broiler chickens under such condition. In this study, 300 one-day-old male broiler chicks (Cobb500™) were randomly assigned into 2 groups with 5 replicates of 30 chicks each. From 21 to 42 days of age, one group was exposed to non-stressed condition at 24 °C and 50% relative humidity (control group), while the other group was exposed to heat stress at 35 °C and 50% relative humidity (HS group). At 42 days of age, blood samples were collected from each group to evaluate stress indicators, immune function, and leukocytes protein synthesis. Production performance was also recorded. Noteworthy, protein synthesis in leukocytes was significantly ( P leukocyte protein synthesis through increasing the level of eEF2 Thr56 phosphorylation may play a key role in the observed decrease in immune function and growth performance with the high mortality rate encountered in broiler chickens under heat stress environment.

  2. Direct (Hetero)arylation Polymerization: Simplicity for Conjugated Polymer Synthesis.

    Science.gov (United States)

    Pouliot, Jean-Rémi; Grenier, François; Blaskovits, J Terence; Beaupré, Serge; Leclerc, Mario

    2016-11-23

    Direct (hetero)arylation polymerization (DHAP) has recently been established as an environmentally benign method for the preparation of conjugated polymers. This synthetic tool features the formation of C-C bonds between halogenated (hetero)arenes and simple (hetero)arenes with active C-H bonds, thereby circumventing the preparation of organometallic derivatives and decreasing the overall production cost of conjugated polymers. Since its inception, selectivity and reactivity of DHAP procedures have been improved tremendously through the careful scrutinity of polymerization outcomes and the fine-tuning of reaction conditions. A broad range of monomers, from simple arenes to complex functionalized heteroarenes, can now be readily polymerized. The successful application of DHAP now leads to nearly defect-free conjugated polymers possessing comparable, if not slightly better, characteristics than their counterparts prepared using classical cross-coupling methods. This comprehensive review describes the mechanisms involved in this process from experimental and theoretical standpoints, presents an up-to-date compendium of materials obtained by this means, and exposes its current limitations and challenges.

  3. Advances in nanoscale alloys and intermetallics: low temperature solution chemistry synthesis and application in catalysis.

    Science.gov (United States)

    Jana, Subhra

    2015-11-21

    Based on the bottom-up chemistry techniques, the size, shape, and composition controlled synthesis of nanoparticles can now be achieved uniformly, which is of great importance to the nanoscience community as well as in modern catalysis research. The low-temperature solution-phase synthesis approach represents one of the most attractive strategies and has been utilized to synthesize nanoscale metals, alloys and intermetallics, including a number of new metastable phases. This perspective will highlight the solution-based nanoparticle synthesis techniques, a low-temperature platform, for the synthesis of size and shape-tunable nanoscale transition metals, alloys, and intermetallics from the literature, keeping a focus on the utility of these nanomaterials in understanding the catalysis. For each solution-based nanoparticle synthesis technique, a comprehensive overview has been given for the reported nanoscale metals, alloys, and intermetallics, followed by critical comments. Finally, their enhanced catalytic activity and durability as novel catalysts have been discussed towards several hydrogenation/dehydrogenation reactions and also for different inorganic to organic reactions. Hence, the captivating advantages of this controllable low-temperature solution chemistry approach have several important implications and together with them this approach provides a promising route to the development of next-generation nanostructured metals, alloys, and intermetallics since they possess fascinating properties as well as outstanding catalytic activity.

  4. Room-temperature Electrochemical Synthesis of Carbide-derived Carbons and Related Materials

    Energy Technology Data Exchange (ETDEWEB)

    Gogotsi, Yury [Drexel Univ., Philadelphia, PA (United States). Nanomaterials Group. Materials Science and Engineering Dept.

    2015-02-28

    This project addresses room-temperature electrochemical etching as an energy-efficient route to synthesis of 3D nanoporous carbon networks and layered 2D carbons and related structures, as well as provides fundamental understanding of structure and properties of materials produced by this method. Carbide-derived-carbons (CDCs) are a growing class of nanostructured carbon materials with properties that are desirable for many applications, such as electrical energy and gas storage. The structure of these functional materials is tunable by the choice of the starting carbide precursor, synthesis method, and process parameters. Moving from high-temperature synthesis of CDCs through vacuum decomposition above 1400°C and chlorination above 400°C, our studies under the previous DOE BES support led to identification of precursor materials and processing conditions for CDC synthesis at temperatures as low as 200°C, resulting in amorphous and highly reactive porous carbons. We also investigated synthesis of monolithic CDC films from carbide films at 250-1200°C. The results of our early studies provided new insights into CDC formation, led to development of materials for capacitive energy storage, and enabled fundamental understanding of the electrolyte ions confinement in nanoporous carbons.

  5. Process assessment of small scale low temperature methanol synthesis

    Science.gov (United States)

    Hendriyana, Susanto, Herri; Subagjo

    2015-12-01

    Biomass is a renewable energy resource and has the potential to make a significant impact on domestic fuel supplies. Biomass can be converted to fuel like methanol via several step process. The process can be split into following main steps: biomass preparation, gasification, gas cooling and cleaning, gas shift and methanol synthesis. Untill now these configuration still has a problem like high production cost, catalyst deactivation, economy of scale and a huge energy requirements. These problems become the leading inhibition for biomass conversion to methanol, which should be resolved to move towards the economical. To address these issues, we developed various process and new configurations for methanol synthesis via methyl formate. This configuration combining two reactors: the one reactor for the carbonylation of methanol and CO to form methyl formate, and the second for the hydrogenolysis of methyl formate and H2 to form two molecule of methanol. Four plant process configurations were compared with the biomass basis is 300 ton/day. The first configuration (A) is equipped with a steam reforming process for converting methane to CO and H2 for increasing H2/CO ratio. CO2 removal is necessary to avoid poisoning the catalyst. COSORB process used for the purpose of increasing the partial pressure of CO in the feed gas. The steam reforming process in B configuration is not used with the aim of reducing the number of process equipment, so expect lower investment costs. For C configuration, the steam reforming process and COSORB are not used with the aim of reducing the number of process equipment, so expect lower investment costs. D configuration is almost similar to the configuration A. This configuration difference is in the synthesis of methanol which was held in a single reactor. Carbonylation and hydrogenolysis reactions carried out in the same reactor one. These processes were analyzed in term of technical process, material and energy balance and economic

  6. Self propagating high temperature synthesis of metal oxides. Reactions in external magnetic fields

    CERN Document Server

    Aguas, M D

    2001-01-01

    The preparation of metal oxides by Self-Propagating High-Temperature Synthesis is reported. The reactions are started with a point source of ignition; typically a hot wire. A synthesis wave is observed moving out from the point source and reactions terminate in seconds. Products obtained can be classified into ferrites (magnetic applications) and stannates (gas sensing applications). Ferrites were synthesised under variable external magnetic fields. The synthesis wave is hotter in the presence of an external magnetic field for hard ferrite synthesis. For spinel ferrites the opposite was observed. Materials synthesised in the field show differences in their bulk magnetic properties (coercivity and saturation magnetisation), structures and microstructures. Combustion reactions in large fields revealed changes in unit cell volume (shrinkage was observed for hard ferrites while expansion was observed for spinel ferrites). SHS synthesised hard ferrites show two distinct components; one has large grain structure co...

  7. Peak Temperature Reduction by Physical Information Driven Behavioral Synthesis with Resource Usage Allocation

    Science.gov (United States)

    Yu, Junbo; Zhou, Qiang; Qu, Gang; Bian, Jinian

    High temperature adversely impacts on circuit's reliability, performance, and leakage power. During behavioral synthesis, both resource usage allocation and resource binding influence thermal profile. Current thermal-aware behavioral syntheses do not utilize location information of resources from floorplan and in addition only focus on binding, ignoring allocation. This paper proposes thermal-aware behavioral synthesis with resource usage allocation. Based on a hybrid metric of physical location information and temperature, we rebind operations and reallocate the number of resources under area constraint. Our approach effectively controls peak temperature and creates even power densities among resources of different types and within resources of the same type. Experimental results show an average of 8.6°C drop in peak temperature and 5.3% saving of total power consumption with little latency overhead.

  8. A Direct DME High Temperature PEM Fuel Cell

    DEFF Research Database (Denmark)

    Vassiliev, Anton; Jensen, Jens Oluf; Li, Qingfeng

    2012-01-01

    Dimethyl ether (DME) has been identified as an alternative to methanol for use in direct fuel cells. It combines the advantages of hydrogen in terms of pumpless fuel delivery and high energy density like methanol, but without the toxicity of the latter. The performance of a direct dimethyl ether...... fuel cell suffers greatly from the very low DME-water miscibility. To cope with the problem polybenzimidazole (PBI) based membrane electrode assemblies (MEAs) have been made and tested in a vapor fed system. PtRu on carbon has been used as anode catalyst and air at ambient pressure was used as oxidant...

  9. Amine-catalyzed direct aldol reactions of hydroxy- and dihydroxyacetone: biomimetic synthesis of carbohydrates.

    Science.gov (United States)

    Popik, Oskar; Pasternak-Suder, Monika; Leśniak, Katarzyna; Jawiczuk, Magdalena; Górecki, Marcin; Frelek, Jadwiga; Mlynarski, Jacek

    2014-06-20

    This article presents comprehensive studies on the application of primary, secondary, and tertiary amines as efficient organocatalysts for the de novo synthesis of ketoses and deoxyketoses. Mimicking the actions of aldolase enzymes, the synthesis of selected carbohydrates was accomplished in aqueous media by using proline- and serine-based organocatalysts. The presented methodology also provides direct access to unnatural L-carbohydrates from the (S)-glyceraldehyde precursor. Determination of the absolute configuration of all obtained sugars was feasible using a methodology consisting of concerted ECD and VCD spectroscopy.

  10. The Use of Original Structure-Directing Agents for the Synthesis of EMC-1 Zeolite

    Directory of Open Access Journals (Sweden)

    Daou T.J.

    2015-03-01

    Full Text Available By using a steric approach, it is possible to design templates matching closely with an inorganic framework. Herein, the design, synthesis and successful application of several di(azacrown ether templates to direct the formation of EMC-1 zeolite (FAU-type are reported. Following a high throughput experiment design, the synthesis gel composition was optimized to obtain well-crystallized materials. Taking into account their respective crystallization rates, their textural and morphological properties were comparable to their counterparts, typically structured by 15-crown-5 ether.

  11. Room and low temperature synthesis of carbon nanofibres

    CERN Document Server

    Boskovic, B O

    2002-01-01

    Carbon nanotubes and nanofibres have attracted attention in recent years as new materials with a number of very promising potential applications. Carbon nanotubes are potential candidates for field emitters in flat panel displays. Carbon nanofibres could also be used as a hydrogen storage material and as a filling material in polymer composites. Carbon nanotubes are already used as tips in scanning probe microscopy due to their remarkable mechanical and electrical properties, and could be soon used as nanotweezers. Use of carbon nanotubes in nanoelectronics will open further miniaturisation prospects. Temperatures ranging from 450 to 1000 deg C have been a required for catalytic growth of carbon nanotubes and nanofibres. Researchers have been trying to reduce the growth temperatures for decades. Low temperature growth conditions will allow the growth of carbon nanotubes on different substrates, such glass (below 650 deg C) and as plastics (below 150 deg C) over relatively large areas, which is especially suit...

  12. Herbivory in global climate change research: direct effects of rising temperature on insect herbivores

    NARCIS (Netherlands)

    Bale, J.S.; Masters, G.J.; Hodkinson, I.D.; Awmack, C.; Bezemer, T.M.; Brown, V.K.; Butterfield, J.; Buse, A.; Coulson, J.C.; Farrar, J.; Good, J.E.G.; Harrington, R.; Hartley, S.; Jones, T.H.; Lindroth, R.L.; Press, M.C.; Symrnioudis, I.; Watt, A.D.; Whittaker, J.B.

    2002-01-01

    This review examines the direct effects of climate change on insect herbivores. Temperature is identified as the dominant abiotic factor directly affecting herbivorous insects. There is little evidence of any direct effects Of CO2 or UVB. Direct impacts of precipitation have been largely neglected

  13. Structural changes in high-temperature synthesis of luminescent alumina ceramics

    Science.gov (United States)

    Zvonarev, S. V.; Kortov, V. S.; Ryabinina, M. V.; Kiryakov, A. N.

    2016-08-01

    Scanning electron microscopy was used to study structural changes in luminescent alumina ceramics which was synthesized from nanopowder at high temperatures in reducing environment. An effect of synthesis parameters on size-distribution of grains, their shape and a number of pores in the samples under study was determined. It was found that in a certain temperature range grains are the same ones in the precursor nanopowder, which is associated with the emergence of nanoparticles of lower aluminum oxides.

  14. Temperature Effects on the Wind Direction Measurement of 2D Solid Thermal Wind Sensors

    Science.gov (United States)

    Chen, Bei; Zhu, Yan-Qing; Yi, Zhenxiang; Qin, Ming; Huang, Qing-An

    2015-01-01

    For a two-dimensional solid silicon thermal wind sensor with symmetrical structure, the wind speed and direction information can be derived from the output voltages in two orthogonal directions, i.e., the north-south and east-west. However, the output voltages in these two directions will vary linearly with the ambient temperature. Therefore, in this paper, a temperature model to study the temperature effect on the wind direction measurement has been developed. A theoretical analysis has been presented first, and then Finite Element Method (FEM) simulations have been performed. It is found that due to symmetrical structure of the thermal wind sensor, the temperature effects on the output signals in the north-south and east-west directions are highly similar. As a result, the wind direction measurement of the thermal wind sensor is approximately independent of the ambient temperature. The experimental results fit the theoretical analysis and simulation results very well. PMID:26633398

  15. The synthesis of [2-13C]2-nitropropane at room temperature and at atmospheric pressure

    NARCIS (Netherlands)

    Jacquemijns M; Zomer G

    1990-01-01

    In this report the synthesis of [2-13C]2-nitropropane at room temperature is described. [2-13C]Acetone was converted into the oxime with hydroxy hydrochloridelamine and sodium carbonate. Treatment with hypobromic acid resulted in 2-13C]2-bromo-2-nitropropane. Hydrogenation with sodium borohydride

  16. Disordered Manganese Oxide Nano-powder Prepared by Low-temperature Synthesis Followed by Acid Treatment

    OpenAIRE

    Koyanaka, Hideki; Hata, Toshihiro; IMAMURA, Yuji

    2005-01-01

    Disordered manganese oxide, prepared by low-temperature synthesis followed by acid treatment is introduced. Aggregated nano-powder of disordered manganese oxide was obtained in this method. The disordered manganese oxide is suitable starting material for the preparation of efficient adsorbents for the removal of harmful metals from the environment.

  17. Synthesis, structure and low temperature study of electric transport ...

    Indian Academy of Sciences (India)

    1. Introduction. Layered perovskite oxides are a promising group of mixed- conducting materials with potential applications for oxygen- separation membranes, gas sensor devices and electrodes of intermediate-temperature solid oxide fuel cells (Moseley and. Williams 1989; Meixner and Lampe 1996; Skinner and Kil-.

  18. Synthesis graphene layer at different waste cooking palm oil temperatures

    Science.gov (United States)

    Robaiah, M.; Rusop, M.; Abdullah, S.; khusaimi, Z.; Azhan, H.; Asli, N. A.

    2017-09-01

    Graphene is one of the most recent carbon nanomaterials that has attracted attention because of its superior properties. The formation of the graphene on the Ni surface appears due to segregation and precipitation of a high amount of carbon from the source material during the cooling process. The growth of graphene at different waste cooking palm oil (WCPO) temperatures using double thermal chemical vapour deposition method (DTCVD) was investigated. The samples were prepared at various vaporization temperatures of WCPO is range from 250 °C to 450 °C by increment 50 °C and the temperature of Ni substrate constant at 900 °C. The structural of the graphene were characterized by using field emission scanning electron microscopy (FESEM), Energy Dispersive X-Ray (EDX) Spectroscopy, UV-Visible and Raman's spectroscopy. FESEM images at optimum temperature (350 °C) display hexagonal shapes since the graphene layers were formed after precipitation of the carbon. It the meantime, UV-Visible spectra shows the sharp peak at 250 nm whereupon the highest of reflectivity value. This peak is an indication the presence of the graphene layers on Ni substrate. The position and half width 2D peak of the Raman spectra were subjected to detail analyses in order to determine the quantity and quality of the graphene layer. At the temperature 350°C, the Raman's spectroscopy result shown the multilayer of the graphene based on I2D/IG ratio is approximately constant (equal to˜0.43).

  19. Low temperature synthesis, structure and magnetic properties of Mn2[VO4]F

    Directory of Open Access Journals (Sweden)

    Daisuke Mori

    2017-12-01

    Full Text Available The compound Mn2[VO4]F was synthesized using a hydrothermal synthesis route at low temperature and its crystal structure was determined from single crystal X-ray diffraction data. Mn2[VO4]F was characterized by magnetic susceptibility and specific heat capacity measurements. Mn2[VO4]F crystallizes with the triplite-type structure, space group C2/c, a = 13.451(3 Å, b = 6.6953(16 Å, c = 10.126(3 Å, β = 116.587(4°, V = 815.6(3 Å3 and Z = 8. The structure consists of a 3D-framework built up of VO4 tetrahedra, and manganese (II polyhedra which form chains running along the [101] and [010] directions. The coordination of the manganese cations and the connectivity between the manganese polyhedra are not defined clearly due to the disorder of the fluoride anions which form zigzag chains along [001]. The magnetic susceptibility follows a Curie–Weiss behavior above 50 K with Θ = −88 K indicating that predominant magnetic interactions are antiferromagnetic. The specific heat capacity and magnetization measurements show that Mn2[VO4]F undergoes a three-dimensional magnetic ordering at TN = 30 K and a canted weak ferromagnetism due to mixed-anion effect.

  20. Learning from directed evolution: Thermus aquaticus DNA polymerase mutants with translesion synthesis activity.

    Science.gov (United States)

    Obeid, Samra; Schnur, Andreas; Gloeckner, Christian; Blatter, Nina; Welte, Wolfram; Diederichs, Kay; Marx, Andreas

    2011-07-04

    DNA is being constantly damaged by endo- and exogenous agents such as reactive oxygen species, chemicals, radioactivity, and ultraviolet radiation. Additionally, DNA is inherently labile, and this can result in, for example, the spontaneous hydrolysis of the glycosidic bond that connects the sugar and the nucleobase moieties in DNA; this results in abasic sites. It has long been obscure how cells achieve DNA synthesis past these lesions, and only recently has it been discovered that several specialized DNA polymerases are involved in translesion synthesis. The underlying mechanisms that render one DNA polymerase competent in translesion synthesis while another DNA polymerase fails are still indistinct. Recently two variants of Taq DNA polymerase that exhibited higher lesion bypass ability than the wild-type enzyme were identified by directed-evolution approaches. Strikingly, in both approaches it was independently found that substitution of a single nonpolar amino acid side chain by a cationic side chain increases the capability of translesion synthesis. Here, we combined both mutations in a single enzyme. We found that the KlenTaq DNA polymerase that bore both mutations superseded the wild-type as well as the respective single mutants in translesion-bypass proficiency. Further insights in the molecular basis of the detected gain of translesion-synthesis function were obtained by structural studies of DNA polymerase variants caught in processing canonical and damaged substrates. We found that increased positive charge of the surface potential in the area proximal to the negatively charged substrates promotes translesion synthesis by KlenTaq DNA polymerase, an enzyme that has very limited naturally evolved capability to perform translesion synthesis. Since expanded positively charged surface potential areas are also found in naturally evolved translesion DNA polymerases, our results underscore the impact of charge on the proficiency of naturally evolved translesion

  1. Synthesis of cadmium chalcogenide nanotubes at room temperature

    KAUST Repository

    Pan, Jun

    2012-10-01

    Cadmium chalcogenide (CdE, E=S, Se, Te) polycrystalline nanotubes have been synthesized from precursor of CdS/cadmium thiolate complex at room temperature. The precursor was hydrothermally synthesized at 180 °C using thioglycolic acid (TGA) and cadmium acetate as starting materials. The transformation from the rod-like precursor of CdS/cadmium thiolate complex to CdS, CdSe and CdTe nanotubes were performed under constant stirring at room temperature in aqueous solution containing S 2-, Se 2- and Te 2-, respectively. The nanotube diameter can be controlled from 150 to 400 nm related to the dimension of templates. The XRD patterns show the cadmium chalcogenide nanotubes all corresponding to face-centered cubic structure. © 2012 Elsevier B.V. All rights reserved.

  2. Nanocarbon synthesis by high-temperature oxidation of nanoparticles

    Science.gov (United States)

    Nomura, Ken-Ichi; Kalia, Rajiv K.; Li, Ying; Nakano, Aiichiro; Rajak, Pankaj; Sheng, Chunyang; Shimamura, Kohei; Shimojo, Fuyuki; Vashishta, Priya

    2016-04-01

    High-temperature oxidation of silicon-carbide nanoparticles (nSiC) underlies a wide range of technologies from high-power electronic switches for efficient electrical grid and thermal protection of space vehicles to self-healing ceramic nanocomposites. Here, multimillion-atom reactive molecular dynamics simulations validated by ab initio quantum molecular dynamics simulations predict unexpected condensation of large graphene flakes during high-temperature oxidation of nSiC. Initial oxidation produces a molten silica shell that acts as an autocatalytic ‘nanoreactor’ by actively transporting oxygen reactants while protecting the nanocarbon product from harsh oxidizing environment. Percolation transition produces porous nanocarbon with fractal geometry, which consists of mostly sp2 carbons with pentagonal and heptagonal defects. This work suggests a simple synthetic pathway to high surface-area, low-density nanocarbon with numerous energy, biomedical and mechanical-metamaterial applications, including the reinforcement of self-healing composites.

  3. Product engineering by high-temperature flame synthesis

    DEFF Research Database (Denmark)

    Johannessen, Tue; Johansen, Johnny; Mosleh, Majid

    also - coalescence of aggregated metal oxide nano-particles. As an example, it is possible produce well-defined spinel structures, e.g. zinc-aluminate (ZnAl2O4), with high specific surface area because the desired phase is formed directly without any need for post calcination. The production of other...

  4. Temperature oscillations near natural nuclear reactor cores and the potential for prebiotic oligomer synthesis

    Science.gov (United States)

    Adam, Zachary R.

    2016-06-01

    Geologic settings capable of driving prebiotic oligomer synthesis reactions remain a relatively unexplored aspect of origins of life research. Natural nuclear reactors are an example of Precambrian energy sources that produced unique temperature fluctuations. Heat transfer models indicate that water-moderated, convectively-cooled natural fission reactors in porous host rocks create temperature oscillations that resemble those employed in polymerase chain reaction (PCR) devices to artificially amplify oligonucleotides. This temperature profile is characterized by short-duration pulses up to 70-100 °C, followed by a sustained period of temperatures in the range of 30-70 °C, and finally a period of relaxation to ambient temperatures until the cycle is restarted by a fresh influx of pore water. For a given reactor configuration, temperature maxima and the time required to relax to ambient temperatures depend most strongly on the aggregate effect of host rock permeability in decreasing the thermal expansion and increasing the viscosity and evaporation temperature of the pore fluids. Once formed, fission-fueled reactors can sustain multi-kilowatt-level power production for 105-106 years, ensuring microenvironmental longevity and chemical output. The model outputs indicate that organic synthesis on young planetary bodies with a sizeable reservoir of fissile material can involve more sophisticated energy dissipation pathways than modern terrestrial analog settings alone would suggest.

  5. Temperature oscillations near natural nuclear reactor cores and the potential for prebiotic oligomer synthesis.

    Science.gov (United States)

    Adam, Zachary R

    2016-06-01

    Geologic settings capable of driving prebiotic oligomer synthesis reactions remain a relatively unexplored aspect of origins of life research. Natural nuclear reactors are an example of Precambrian energy sources that produced unique temperature fluctuations. Heat transfer models indicate that water-moderated, convectively-cooled natural fission reactors in porous host rocks create temperature oscillations that resemble those employed in polymerase chain reaction (PCR) devices to artificially amplify oligonucleotides. This temperature profile is characterized by short-duration pulses up to 70-100 °C, followed by a sustained period of temperatures in the range of 30-70 °C, and finally a period of relaxation to ambient temperatures until the cycle is restarted by a fresh influx of pore water. For a given reactor configuration, temperature maxima and the time required to relax to ambient temperatures depend most strongly on the aggregate effect of host rock permeability in decreasing the thermal expansion and increasing the viscosity and evaporation temperature of the pore fluids. Once formed, fission-fueled reactors can sustain multi-kilowatt-level power production for 10(5)-10(6) years, ensuring microenvironmental longevity and chemical output. The model outputs indicate that organic synthesis on young planetary bodies with a sizeable reservoir of fissile material can involve more sophisticated energy dissipation pathways than modern terrestrial analog settings alone would suggest.

  6. Direct integration of polycrystalline graphene into light emitting diodes by plasma-assisted metal-catalyst-free synthesis.

    Science.gov (United States)

    Kim, Yong Seung; Joo, Kisu; Jerng, Sahng-Kyoon; Lee, Jae Hong; Moon, Daeyoung; Kim, Jonghak; Yoon, Euijoon; Chun, Seung-Hyun

    2014-03-25

    The integration of graphene into devices is a challenging task because the preparation of a graphene-based device usually includes graphene growth on a metal surface at elevated temperatures (∼1000 °C) and a complicated postgrowth transfer process of graphene from the metal catalyst. Here we report a direct integration approach for incorporating polycrystalline graphene into light emitting diodes (LEDs) at low temperature by plasma-assisted metal-catalyst-free synthesis. Thermal degradation of the active layer in LEDs is negligible at our growth temperature, and LEDs could be fabricated without a transfer process. Moreover, in situ ohmic contact formation is observed between DG and p-GaN resulting from carbon diffusion into the p-GaN surface during the growth process. As a result, the contact resistance is reduced and the electrical properties of directly integrated LEDs outperform those of LEDs with transferred graphene electrodes. This relatively simple method of graphene integration will be easily adoptable in the industrialization of graphene-based devices.

  7. Synthesis of MIL-100(Fe at Low Temperature and Atmospheric Pressure

    Directory of Open Access Journals (Sweden)

    Jing Shi

    2013-01-01

    Full Text Available MIL-100(Fe, a mesoporous metal-organic framework (MOF, has a large BET specific surface area and pore volume with the presence of a significant amount of accessible Lewis acid metal sites upon dehydration. The structural characteristics of MIL-100(Fe make it a good candidate for potential applications in gas storage, separation, and heterogeneous catalysis. Mainly, this MOF is obtained by the hydrothermal synthesis in a Teflon-lined autoclave at high temperature (>150°C under static conditions. However, this method has several disadvantages such as high temperature, high (autogenous pressure, long time, and comparable low MOF yield. Therefore, development of a facile method for synthesis of MIL-100(Fe is vitally important for fundamental understanding and practical application. Herein, MIL-100(Fe is synthesized by a facile low-temperature (90% still could be achieved, suggesting that this simple and energy saving method has the potential to be used practically.

  8. Numerical investigation of high temperature synthesis gas premixed combustion via ANSYS Fluent

    Directory of Open Access Journals (Sweden)

    Pashchenko Dmitry

    2018-01-01

    Full Text Available A numerical model of the synthesis gas pre-mixed combustion is developed. The research was carried out via ANSYS Fluent software. Verification of the numerical results was carried out using experimental data. A visual comparison of the flame contours that obtained by the synthesis gas combustion for Re = 600; 800; 1000 was performed. A comparison of the wall temperature of the combustion chamber, obtained with the help of the developed model, with the results of a physical experiment was also presented. For all cases, good convergence of the results is observed. It is established that a change in the temperature of the syngas/air mixture at the inlet to the combustion chamber does not significantly affect the temperature of the combustion products due to the dissipation of the H2O and CO2 molecules. The obtained results are of practical importance for the design of heat engineering plants with thermochemical heat recovery.

  9. Low temperature decomposition of metal borohydride drives autogenous synthesis of MgB2

    Science.gov (United States)

    Mackinnon, I. D. R.; Shahbazi, M.; Alarco, J. A.; Talbot, P. C.

    2017-05-01

    We describe a low temperature, autogenous pressure method to synthesise mm-scale MgB2 aggregates with highly connected grains. The decomposition of metal borohydrides such as NaBH4 and KBH4 at low temperature (i.e. 30 min then a ramp to 450 °C Magnetic measurements of MgB2 aggregates show a grain connectivity comparable to powders produced at higher temperature (> 800 °C) and suggests that this synthesis approach may be effective for ex situ wire production.

  10. Synthesis of zinc oxide microrods and nano-fibers with dominant exciton emission at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ramos-Brito, F., E-mail: fro_brito@yahoo.com.m [Laboratorio de Materiales Optoelectronicos del Centro de Ciencias de Sinaloa, Ave. de las Americas 2771 Col. Villa Universidad 80010, Culiacan, Sinaloa (Mexico); Alejo-Armenta, C. [Laboratorio de Materiales Optoelectronicos del Centro de Ciencias de Sinaloa, Ave. de las Americas 2771 Col. Villa Universidad 80010, Culiacan, Sinaloa (Mexico); Garcia-Hipolito, M. [Departamento de Materiales Metalicos y Ceramicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, AP 70-360, Coyoacan 04510, DF (Mexico); Camarillo, E.; Hernandez A, J. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, AP 20-364, Alvaro Obregon 01000, DF (Mexico); Falcony, C. [Departamento de Fisica, CINVESTAV-IPN, AP 14-740, 07000, DF (Mexico); Murrieta S, H. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, AP 20-364, Alvaro Obregon 01000, DF (Mexico)

    2011-05-15

    Employing a simple chemical synthesis method, hexagonal-shaped zinc oxide microrods and zinc oxide nano-fibers were deposited on pyrex-glass and aluminum substrates, respectively. Both kinds of deposits showed zincite crystalline phase with lattice parameters: a=3.2498 A and c=5.2066 A. Microrods showed very uniform wide and large sizes of around 1 and 10 {mu}m, respectively. Both deposits were homogeneous over all substrate surfaces. Microrods and nano-fibers resulted with good optical quality and with preferential crystalline growth in [1 0 1 0]and [0 0 0 1]directions. The principal optical characteristics for both microrods and nano-fibers were: a) room-temperature photo and cathodo-luminescent spectra with strong exciton emission centered around 390 nm and with FWHMs around 125 and 160 meV, respectively, b) poor photo and cathode-luminescent emissions in the visible region of the electromagnetic spectrum, c) energy band gap of 3.32 eV, d) good emission efficiency supported by the not-required high energy densities to obtain strong exciton emission and e) good ZnO stoichiometry endorsed by photoluminescent results. These characteristics make of these microrods and nano-fibers good for potential photonic applications. - Research highlights: {yields} Microrods and nano-fibers resulted with good optical quality and with preferential crystalline growth in [1 0 1 0]and [0 0 0 1]directions. {yields} Microrods and nano-fibers resulted with good emission efficiency supported by the not-required high energy densities to obtain strong exciton emission. {yields} The wet chemical method is appropriated for deposition of microrods and nano-fibers with the desired optical properties for its possible application in photonics.

  11. Porous Diatomite-Immobilized Cu–Ni Bimetallic Nanocatalysts for Direct Synthesis of Dimethyl Carbonate

    Directory of Open Access Journals (Sweden)

    Yong Chen

    2012-01-01

    Full Text Available A series of diatomite-immobilized Cu–Ni bimetallic nanocatalysts was prepared under ultrasonication and evaluated for the direct synthesis of dimethyl carbonate under various conditions. Upon being fully characterized by TPR, TPD, BET, SEM, XRD, and XPS methodologies, it is found that the bimetallic composite is effectively alloyed and well immobilized inside or outside the pore of diatomite. Under the optimal conditions of 1.2 MPa and 120∘C, the prepared catalyst with loading of 15% exhibited the highest methanol conversion of 6.50% with DMC selectivity of 91.2% as well as more than 10-hour lifetime. The possible reaction mechanism was proposed and discussed in detail. To our knowledge, this is the first report to use diatomite as a catalyst support for direct DMC synthesis from methanol and CO2.

  12. Protecting-group-free one-pot synthesis of glycoconjugates directly from reducing sugars.

    Science.gov (United States)

    Lim, David; Brimble, Margaret A; Kowalczyk, Renata; Watson, Andrew J A; Fairbanks, Antony John

    2014-10-27

    The conversion of sugars into glycomimetics typically involves multiple protecting-group manipulations. The development of methodology allowing the direct aqueous conversion of free sugars into glycosides, and mimics of oligosaccharides and glycoconjugates in a high-yielding and stereoselective process is highly desirable. The combined use of 2-azido-1,3-dimethylimidazolinium hexafluorophosphate and the Cu-catalyzed Huisgen cycloaddition allowed the synthesis of a range of glycoconjugates in a one-step reaction directly from reducing sugars under aqueous conditions. The reaction, which is completely stereoselective, may be applied to the convergent synthesis of triazole-linked glycosides, oligosaccharides, and glycopeptides. The procedure provides a method for the one-pot aqueous ligation of oligosaccharides and peptides bearing alkyne side chains. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Direct Utilization of Coal Syngas in High Temperature Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Celik, Ismail B. [West Virginia University, Morgantown, WV (United States)

    2014-10-30

    This EPSCoR project had two primary goals: (i) to build infrastructure and work force at WVU to support long-term research in the area of fuel cells and related sciences; (ii) study effects of various impurities found in coal-syngas on performance of Solid Oxide Fuel Cells (SOFC). As detailed in this report the WVU research team has made significant accomplishments in both of these areas. What follows is a brief summary of these accomplishments: State-of-the-art test facilities and diagnostic tools have been built and put into use. These include cell manufacturing, half-cell and full-cell test benches, XPS, XRD, TEM, Raman, EDAX, SEM, EIS, and ESEM equipment, unique in-situ measurement techniques and test benches (Environmental EM, Transient Mass-Spectrometer-MS, and IR Optical Temperature measurements). In addition, computational capabilities have been developed culminating in a multi-scale multi-physics fuel cell simulation code, DREAM-SOFC, as well as a Beowulf cluster with 64 CPU units. We have trained 16 graduate students, 10 postdoctoral fellows, and recruited 4 new young faculty members who have actively participated in the EPSCoR project. All four of these faculty members have already been promoted to the tenured associate professor level. With the help of these faculty and students, we were able to secure 14 research awards/contracts amounting to a total of circa $5.0 Million external funding in closely related areas of research. Using the facilities mentioned above, the effects of PH3, HCl, Cl2, and H2S on cell performance have been studied in detail, mechanisms have been identified, and also remedies have been proposed and demonstrated in the laboratory. For example, it has been determined that PH3 reacts rapidly with Ni to from secondary compounds which may become softer or even melt at high temperature and then induce Ni migration to the surface of the cell changing the material and micro-structural properties of the cell drastically. It is found that

  14. Direct synthesis of hydrogen peroxide using in-situ selective layer

    Science.gov (United States)

    Makertihartha, I. G. B. N.; Dharmawijaya, P. T.; Zunita, M.; Wenten, I. G.

    2017-05-01

    Hydrogen peroxide is used in broad range of application such as oxidation, bleaching, and wastewater treatment. Conventionally, hydrogen peroxide is synthesized using reduction oxidation cycle of anthraquinones from hydrogen and oxygen. This process is rather complex and requires considerable amount of energy. Direct synthesis of hydrogen peroxide is one attractive approach to said problems. However, activity and selectivity is the main problem of direct synthesis since the reactants form explosive mixture. Dilution of gasses is commonly used to solve said problem but limit the amount of reactants in the liquid solvent. Membrane reactor can separate pure reactant gases and also constantly feed them over the length of reaction channel. Pd-Ag alloy membrane can be used both as a catalyst and hydrogen dosage. There are some studies that investigate the use of Pd based membrane reactor but still no commercial application. This paper will bring basic concept of Pd based membrane reactor for direct synthesis of hydrogen peroxide. Special attention will be given to current hurdles and their possible solutions that lead to facile production of hydrogen peroxide. Furthermore, recent trends towards utilization of micro reactor will also be discussed.

  15. Depression of leukocyte protein synthesis, immune function and growth performance induced by high environmental temperature in broiler chickens.

    Science.gov (United States)

    Kamel, Nancy N; Ahmed, Ayman M H; Mehaisen, Gamal M K; Mashaly, Magdi M; Abass, Ahmed O

    2017-04-28

    In tropical and semitropical regions, raising broiler chickens out of their thermal comfort zone can cause an added economic loss in the poultry industry. The cause for the deleterious effects on immunity and growth performance of broilers under high environmental temperatures is still poorly understood. Therefore, the aim of the current investigation was to evaluate the effect of heat stress on leukocytes protein synthesis and immune function as a possible direct cause of low performance in broiler chickens under such condition. In this study, 300 one-day-old male broiler chicks (Cobb500™) were randomly assigned into 2 groups with 5 replicates of 30 chicks each. From 21 to 42 days of age, one group was exposed to non-stressed condition at 24 °C and 50% relative humidity (control group), while the other group was exposed to heat stress at 35 °C and 50% relative humidity (HS group). At 42 days of age, blood samples were collected from each group to evaluate stress indicators, immune function, and leukocytes protein synthesis. Production performance was also recorded. Noteworthy, protein synthesis in leukocytes was significantly (P broiler performance indicate that HS birds had a significant (P growth performance with the high mortality rate encountered in broiler chickens under heat stress environment.

  16. The direct oxidative diene cyclization and related reactions in natural product synthesis

    Directory of Open Access Journals (Sweden)

    Juliane Adrian

    2016-09-01

    Full Text Available The direct oxidative cyclization of 1,5-dienes is a valuable synthetic method for the (diastereoselective preparation of substituted tetrahydrofurans. Closely related reactions start from 5,6-dihydroxy or 5-hydroxyalkenes to generate similar products in a mechanistically analogous manner. After a brief overview on the history of this group of transformations and a survey on mechanistic and stereochemical aspects, this review article provides a summary on applications in natural product synthesis. Moreover, current limitations and future directions in this area of chemistry are discussed.

  17. Polymer-directed synthesis of metal oxide-containing nanomaterials for electrochemical energy storage.

    Science.gov (United States)

    Mai, Yiyong; Zhang, Fan; Feng, Xinliang

    2014-01-07

    Metal oxide-containing nanomaterials (MOCNMs) of controllable structures at the nano-scale have attracted considerable interest because of their great potential applications in electrochemical energy storage devices, such as lithium-ion batteries (LIBs) and supercapacitors. Among many structure-directing agents, polymers and macromolecules, including block copolymers (BCPs) and graphene, exhibit distinct advantages in the template-assisted synthesis of MOCNMs. In this feature article, we introduce the controlled preparation of MOCNMs employing BCPs and graphene as structure-directing agents. Typical synthetic strategies are presented for the control of structures and sizes as well as the improvement of physical properties and electrochemical performance of MOCNMs in LIBs and supercapacitors.

  18. Polycrystalline methane hydrate: Synthesis from superheated ice, and low-temperature mechanical properties

    Science.gov (United States)

    Stern, L.A.; Kirby, S.H.; Durham, W.B.

    1998-01-01

    We describe a new and efficient technique to grow aggregates of pure methane hydrate in quantities suitable for physical and material properties testing. Test specimens were grown under static conditions by combining cold, pressurized CH4 gas with granulated H2O ice, and then warming the reactants to promote the reaction CH4(g) + 6H2O(s???1) ??? CH4??6H2O (methane hydrate). Hydrate formation evidently occurs at the nascent ice/liquid water interface on ice grain surfaces, and complete reaction was achieved by warming the system above the ice melting point and up to 290 K, at 25-30 MPa, for approximately 8 h. The resulting material is pure, cohesive, polycrystalline methane hydrate with controlled grain size and random orientation. Synthesis conditions placed the H2O ice well above its melting temperature while reaction progressed, yet samples and run records showed no evidence for bulk melting of the unreacted portions of ice grains. Control experiments using Ne, a non-hydrate-forming gas, showed that under otherwise identical conditions, the pressure reduction and latent heat associated with ice melting are easily detectable in our fabrication apparatus. These results suggest that under hydrate-forming conditions, H2O ice can persist metastably to temperatures well above its ordinary melting point while reacting to form hydrate. Direct observations of the hydrate growth process in a small, high-pressure optical cell verified these conclusions and revealed additional details of the hydrate growth process. Methane hydrate samples were then tested in constant-strain-rate deformation experiments at T = 140-200 K, Pc = 50-100 MPa, and ?? = 10-4 10-6 s-1. Measurements in both the brittle and ductile fields showed that methane hydrate has measurably different strength than H2O ice, and work hardens to an unusually high degree compared to other ices as well as to most metals and ceramics at high homologous temperatures. This work hardening may be related to a changing

  19. Influence of Plasma Jet Temperature Profiles in Arc Discharge Methods of Carbon Nanotubes Synthesis.

    Science.gov (United States)

    Raniszewski, Grzegorz; Wiak, Slawomir; Pietrzak, Lukasz; Szymanski, Lukasz; Kolacinski, Zbigniew

    2017-02-23

    One of the most common methods of carbon nanotubes (CNTs) synthesis is application of an electric-arc plasma. However, the final product in the form of cathode deposit is composed of carbon nanotubes and a variety of carbon impurities. An assay of carbon nanotubes produced in arc discharge systems available on the market shows that commercial cathode deposits contain about 10% CNTs. Given that the quality of the final product depends on carbon-plasma jet parameters, it is possible to increase the yield of the synthesis by plasma jet control. Most of the carbon nanotubes are multiwall carbon nanotubes (MWCNTs). It was observed that the addition of catalysts significantly changes the plasma composition, effective ionization potential, the arc channel conductance, and in effect temperature of the arc and carbon elements flux. This paper focuses on the influence of metal components on plasma-jet forming containing carbon nanotubes cathode deposit. The plasma jet temperature control system is presented.

  20. Influence of Plasma Jet Temperature Profiles in Arc Discharge Methods of Carbon Nanotubes Synthesis

    Directory of Open Access Journals (Sweden)

    Grzegorz Raniszewski

    2017-02-01

    Full Text Available One of the most common methods of carbon nanotubes (CNTs synthesis is application of an electric-arc plasma. However, the final product in the form of cathode deposit is composed of carbon nanotubes and a variety of carbon impurities. An assay of carbon nanotubes produced in arc discharge systems available on the market shows that commercial cathode deposits contain about 10% CNTs. Given that the quality of the final product depends on carbon–plasma jet parameters, it is possible to increase the yield of the synthesis by plasma jet control. Most of the carbon nanotubes are multiwall carbon nanotubes (MWCNTs. It was observed that the addition of catalysts significantly changes the plasma composition, effective ionization potential, the arc channel conductance, and in effect temperature of the arc and carbon elements flux. This paper focuses on the influence of metal components on plasma-jet forming containing carbon nanotubes cathode deposit. The plasma jet temperature control system is presented.

  1. The effect of temperature in flux-assisted synthesis of SnNb2O6

    KAUST Repository

    Noureldine, Dalal

    2014-10-03

    A flux-assisted method was used to synthesize SnNb2O6 as a visible-light-responsive metal oxide photocatalyst. The role of synthesis temperature was investigated in detail using different reaction temperatures (300, 500, 600, 800, 1000 °C). The obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller method (BET). The synthesis with SnCl2 as a flux led to tin niobate particles in the platelet morphology with smooth surfaces. The synthesized crystal showed 2D anisotropic growth along the (600) plane as the flux ratio increased. The particles synthesized with a high reactant to flux ratio (1:10 or higher) exhibited improved photocatalytic activity for hydrogen evolution from an aqueous methanol solution under visible radiation (λ > 420 nm). © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  2. Ambient-temperature synthesis of nanocrystalline ZnO and its application in the generation of hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Perales-Perez, O.J.; Singh, S.P. [University of Puerto Rico, Mayagueez, PR 00681 (United States); Tomar, M.S.; Watanabe, A.; Arai, T.; Kasuya, A.; Tohji, K. [Tohoku University, Aramaki-Aza, Aoba-ku, Sendai 980-8579 (Japan)

    2004-03-01

    The conditions leading to the direct formation of nanocrystalline ZnO particles from aqueous solutions at 25 C are presented. The synthesis of ZnO was made possible by the suitable selection of the solution chemistry and the control of the alkaline conditions established during the formation and conversion of the precursor solid. XRD and FT-IR analyses revealed that the progressive removal of molecular and coordinated water from the precursor basic zinc sulphate and the diminution of sulphate contents took place at a temperature as low as 25 C, making unnecessary any further thermal treatment of the as-synthesized powders. SEM observations evidenced the formation of sub-micron aggregates of ZnO (sizes below 100 nm). Depending on synthesis and precipitation conditions, it was possible to decrease the crystallite size from 25 down to 11 nm. The ambient-temperature ZnO nanocrystals were used in the photo-catalytic generation of hydrogen from alkaline Na{sub 2}S aqueous solutions. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Formulation and synthesis of hydrogels having lower critical solution temperature near body temperature

    Science.gov (United States)

    Abidin, A. Z.; Graha, H. P. R.; Trirahayu, D. A.

    2017-07-01

    Copolymerization between bacterial cellulose nanocrystal (CN) and methyl cellulose (MC) was carried out using UV light to produce a biocompatible hydrogel at body temperature and liquid at room temperature. Viscosity and salt effect of the MC and copolymer solution at room temperature and its Lower Critical Solution Temperature (LCST) were evaluated. The analysis showed that the higher concentration of methyl cellulose and salt content in the solution produced lower LCST and higher solution viscosity. All samples of polymer solution with MC concentrations of 1 and 2% have a viscosity less than 5000 cP at room temperature. The solutions with MC concentration of 1, 2, and 3% have respectively LCST of 59, 58, and 57°C, while its copolymer solutions with CN concentration of 0.1, 0.3, and 0.5% have respectively LCST of 55, 51, and 41°C. The salt addition to the solution of MC-CN copolymer with concentrations of 1x and 1.5x Phosphat Buffered Saline (PBS) produces respectively LCST of 47 and 38°C. The results suggest that the copolymer solution of MC-CN could produce a lower LCST and the addition of salt could amplify the effect of LCST decrease that can be used to produce a biocompatible hydrogel with LCST as close as body temperature.

  4. The synthesis of [2-13C]2-nitropropane at room temperature and at atmospheric pressure

    OpenAIRE

    Jacquemijns M; Zomer G

    1990-01-01

    In this report the synthesis of [2-13C]2-nitropropane at room temperature is described. [2-13C]Acetone was converted into the oxime with hydroxy hydrochloridelamine and sodium carbonate. Treatment with hypobromic acid resulted in 2-13C]2-bromo-2-nitropropane. Hydrogenation with sodium borohydride gave [2-13C]2-nitropropane in 14,3% overall yield.

  5. Sol-gel synthesis of carbon based materials reinforced ultra high temperature ceramic composites

    OpenAIRE

    Wang, Xiaojing

    2017-01-01

    This Ph.D. research is based on the development of novel sol-gel techniques for synthesis of nanostructured ultra high temperature ceramics (UHTCs) and subsequent spark plasma sintering (SPS) for densifying the UHTC composites. The liquid nature of the sol-gel process offers advantages such as high purity and ability for mixing and infiltration, and thus it can overcome some shortcomings of the conventional power processing of ceramics. SPS delivers microstructures with good density and fine ...

  6. Effects of synthesis temperature on the microstructures and basic dyes adsorption of titanate nanotubes.

    Science.gov (United States)

    Lee, Chung-Kung; Lin, Kuen-Song; Wu, Chian-Fu; Lyu, Meng-Du; Lo, Chao-Chun

    2008-02-11

    The adsorption of two basic dyes (Basic Green 5 (BG5) and Basic Violet 10 (BV10)) onto titanate nanotubes (TNT) that were prepared via a hydrothermal method with different synthesis temperatures was studied to examine the potential of TNT for the removal of basic dyes from aqueous solution. Effects of synthesis temperature on the microstructures of TNT were characterized with transmission electron microscopy (TEM), X-ray diffraction (XRD), and nitrogen adsorption-desorption isotherms. For synthesis temperature greater than 160 degrees C, the microstructure of titanate might transform from nanotube into nanorod accompanying with the sharp decrease in the titanate interlayer spacing, BET surface area, and pore volume. Effects of the pore structure variation on the basic dyes adsorption of TNT were discussed. Moreover, the adsorption mechanisms of basic dyes from aqueous solution onto TNT were examined with the aid of model analyses of the adsorption equilibrium and kinetic data of BG5 and BV10. The regeneration of TNT was also briefly discussed.

  7. Direct Synthesis of Polymer Nanotubes via Aqueous Dispersion Polymerization of Cyclodextrin/Styrene Complex.

    Science.gov (United States)

    Chen, Xi; Liu, Lei; Huo, Meng; Zeng, Min; Peng, Liao; Feng, Anchao; Wang, Xiaosong; Yuan, Jinying

    2017-10-17

    We report a one-step synthesis of nanotubes by RAFT dispersion polymerization of cyclodextrin/styrene (CD/St) complexes directly in water. The resulted amphiphilic PEG-b-PS diblock copolymers self-assemble in situ into nanoparticles with various morphologies. Spheres, worms, lamellae, and nanotubes were controllably obtained. Because of the complexation, the swelling degree of polystyrene (PS) blocks by free St is limited, resulting limited mobility of PS chains. Consequently, kinetically trapped lamellae and nanotubes were obtained instead of spherical vesicles. During the formation of nanotubes, small vesicles firstly formed at the ends of the tape-like lamellae, then grew and fused into nanotubes with limited chain rearrangement. The introduction of host-guest interaction based on CDs enables the aqueous dispersion polymerization of water-immiscible monomers, and produces kinetically trapped nanostructures, which could be a powerful technique for nanomaterials synthesis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Directionally Solidified NiAl-Based Alloys Studied for Improved Elevated-Temperature Strength and Room-Temperature Fracture Toughness

    Science.gov (United States)

    Whittenberger, J. Daniel; Raj, Sai V.; Locci, Ivan E.; Salem, Jonathan A.

    2000-01-01

    Efforts are underway to replace superalloys used in the hot sections of gas turbine engines with materials possessing better mechanical and physical properties. Alloys based on the intermetallic NiAl have demonstrated potential; however, they generally suffer from low fracture resistance (toughness) at room temperature and from poor strength at elevated temperatures. Directional solidification of NiAl alloyed with both Cr and Mo has yielded materials with useful toughness and elevated-temperature strength values. The intermetallic alloy NiAl has been proposed as an advanced material to extend the maximum operational temperature of gas turbine engines by several hundred degrees centigrade. This intermetallic alloy displays a lower density (approximately 30-percent less) and a higher thermal conductivity (4 to 8 times greater) than conventional superalloys as well as good high-temperature oxidation resistance. Unfortunately, unalloyed NiAl has poor elevated temperature strength (approximately 50 MPa at 1027 C) and low room-temperature fracture toughness (about 5 MPa). Directionally solidified NiAl eutectic alloys are known to possess a combination of high elevated-temperature strength and good room-temperature fracture toughness. Research has demonstrated that a NiAl matrix containing a uniform distribution of very thin Cr plates alloyed with Mo possessed both increased fracture toughness and elevated-temperature creep strength. Although attractive properties were obtained, these alloys were formed at low growth rates (greater than 19 mm/hr), which are considered to be economically unviable. Hence, an investigation was warranted of the strength and toughness behavior of NiAl-(Cr,Mo) directionally solidified at faster growth rates. If the mechanical properties did not deteriorate with increased growth rates, directional solidification could offer an economical means to produce NiAl-based alloys commercially for gas turbine engines. An investigation at the NASA Glenn

  9. Exploration of the role of anions in the synthesis of Cr containing mesoporous materials at room temperature

    NARCIS (Netherlands)

    Mahony, L; Wu, C.M.; Kibombo, H.S.; Thiruppathi, E.; Baltrusaitis, Jonas; Rasalingam, S; Koodali, R.T.

    2013-01-01

    Chromium containing mesoporous silica materials were synthesized via a modified Stöber synthesis at room temperature. The chromium ion loading and the effect of counter ion in the synthesis were studied in detail. The mesoporous materials were extensively characterized by powder X-ray diffraction

  10. A direct digital control of the temperature for the VENUS vertex chamber at TRISTAN

    Energy Technology Data Exchange (ETDEWEB)

    Ohama, T. (National Laboratory for High Energy Physics, KEK, Tsukuba, Ibaraki 305 (Japan)); Ishihara, N. (National Laboratory for High Energy Physics, KEK, Tsukuba, Ibaraki 305 (Japan)); Utsumi, M. (National Laboratory for High Energy Physics, KEK, Tsukuba, Ibaraki 305 (Japan)); Yamada, Y. (National Laboratory for High Energy Physics, KEK, Tsukuba, Ibaraki 305 (Japan))

    1994-12-01

    A trial to introduce a DDC (direct digital control) system has been carried out in order to stabilize the temperature of the VENUS vertex chamber so as to obtain a spatial resolution of better than 50 [mu]m. The temperature is controlled to within 0.1 C in the gas near to the chamber endplates. ((orig.))

  11. Physiological responses to temperature and haeme synthesis modifiers in earthworm Lumbricus terrestris (Annelida: Oligochaeta).

    Science.gov (United States)

    Khan, M A Q; Khan, Munawwar Ali; Hurlock, Peter; Ahmed, S A

    2012-01-01

    Earthworms (Lumbricus terrestris) acclimated at 2° and 6°C above their average habitat temperature (10°C) had respectively 15 and 40% higher rate of respiration than those at habitat temperature. At 14°C, the rate of respiration and blood hemoglobin (Hb) concentration both increased by ∼60 and 50%, respectively, of the values at habitat temperature. At higher temperatures the rate of respiration and Hb synthesis started decreasing. At 20-23°C, the respiration and Hb concentration decreased respectively by about 85% and 35% of that at 14°C. Decrease in blood Hb concentration at higher temperatures appeared to be due to the lowering of the activity of blood enzyme δ-aminolaevulinic acid dehydratase (ALAD). Exposure of 20-23°C-acclimated pale worms to ALAD inhibitor (lead), lowered the already compromised rate of respiration and blood Hb concentration; while exposure to hexachlorobenzene (HCB, inducer of haeme synthesis) and ferric chloride (enhancer of haeme synthesis) did not overcome the inhibitory effect of high temperature on Hb synthesis. At 20-23°C the affinity of Hb for oxygen also decreased as indicated by the lowering of oxy-Hb (HbO) concentration in blood. The lowering of concentration of blood Hb and its affinity for oxygen may lower the amount of oxygen delivered to cells, which may limit the level of aerobic metabolism (glycolysis, oxidative phosphorylation), as indicated by an increase in blood glucose concentration and a decrease in in vitro activities of mitochondrial electron transport system components (ETS) namely NADH-cytochrome c reductase, succinate dehydrogenase, cytochrome c oxidase, and ATPases. Although the oxygen concentration in air, at sea level, does not decrease significantly from 6° to 20-23°C (lack of hypoxia), lowering of both Hb and HbO concentrations by high temperature may cause significant hypoxemia. The latter may lead to inhibition of the activity of muscle mitochondrial respiratory enzymes (ETS). The resulting

  12. Synthesis of barium titanate powders by low-temperature aqueous synthesis using a new segmented flow tubular reactor

    Energy Technology Data Exchange (ETDEWEB)

    Bowen, P.; Donnet, M. [Swiss Federal Inst. of Technology, Lausanne (Switzerland). Materials Science and Eng. Dept.; Testino, A.; Viviani, M.; Buscaglia, M.T.; Buscaglia, V. [National Research Council, Genoa (Italy). Inst. for Physical Chemistry of Materials; Nanni, P. [Chemical and Process Engineering Dept. - Univ. of Genoa (Italy)

    2002-07-01

    Barium titanate powders have been synthesised using a low temperature aqueous synthesis (LTAS) method in both batch and Segmented Flow Tubular Reactors. For similar stoichiometries the SFTR powder shows a much lower degree of aggregation with 80% particles <100 nm for the SFTR and only 57% <100 nm for the batch case. Specific surface areas for the SFTR powder are also higher at around 50 m{sup 2}/g compared to 38 m{sup 2}/g for the batch powders indicative of primary particle sizes of 24 nm (SFTR) and 31 nm (batch). After freeze drying, redispersion and slip casting the SFTR powder gives improved sintered densities (95.5 from 93.25%) the sintered microstructures are very similar. (orig.)

  13. In situ synthesis of nanocomposite membranes: comprehensive improvement strategy for direct methanol fuel cells.

    Science.gov (United States)

    Rao, Siyuan; Xiu, Ruijie; Si, Jiangju; Lu, Shanfu; Yang, Meng; Xiang, Yan

    2014-03-01

    In situ synthesis is a powerful approach to control nanoparticle formation and consequently confers extraordinary properties upon composite membranes relative to conventional doping methods. Herein, uniform nanoparticles of cesium hydrogen salts of phosphotungstic acid (CsPW) are controllably synthesized in situ in Nafion to form CsPW–Nafion nanocomposite membranes with both improved proton conductivity and methanol-crossover suppression. A 101.3% increase of maximum power density has been achieved relative to pristine Nafion in a direct methanol fuel cell (DMFC), indicating a potential pathway for large-scale fabrication of DMFC alternative membranes.

  14. Recent progress in the direct synthesis of hierarchical zeolites: synthetic strategies and characterization methods

    KAUST Repository

    Liu, Zhaohui

    2017-06-16

    Hierarchically structured zeolites combine the merits of microporous zeolites and mesoporous materials to offer enhanced molecular diffusion and mass transfer without compromising the inherent catalytic activities and selectivity of zeolites. This short review gives an introduction to the synthesis strategies for hierarchically structured zeolites with emphasis on the latest progress in the route of ‘direct synthesis’ using various templates. Several characterization methods that allow us to evaluate the ‘quality’ of complex porous structures are also introduced. At the end of this review, an outlook is given to discuss some critical issues and challenges regarding the development of novel hierarchically structured zeolites as well as their applications.

  15. Directing factors affecting the synthesis of a MFI-type zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Vinaches, P.; Pergher, S.B.C. [Universidade Federal de Rio Grande do Norte (UFRN), RN (Brazil); Lopes, C.W. [Institute of Chemical Technology, Mumbai (India); Gomez-Hortiguela, L. [Instituto de Catalisis y Petroleoquimica, Madrid (Spain); Finger, P.H.; Silva, B.A. da; Dallago, R.M.; Mignoni, M.L. [Universidade Regional Integrada do Alto Uruguai e das Missoes (URI), Erechim, RS (Brazil)

    2016-07-01

    Full text: Zeolites are crystalline tectosilicates constituted by (TO4) tetrahedra connected through the oxygens of their vertices. The importance of these materials is that their properties differ, due to their variable compositions and structures, leading to the possibility of applying them into different industries, for example, as catalyst in petroleum industry or sensors in quality control. One of the big questions in this area is about the understanding of the chemistry that directs to one or another type of zeolite. Another important question is the search of new zeolitic structures for new applications. One approach to answer both is the study of the structure-directing agents, which are inorganic or organic molecules used in the synthesis of zeolites. New and already-used molecules have been studied within different synthesis conditions and different techniques, as characterization or computational studies. And several attempts of rationalization were and, still, will be performed. In this research, an imidazolium-based compound was studied in hydrothermal zeolite synthesis as organic structure-directing agent (OSDA). The products were obtained with Si/Al or Si/(Al+Zn) compositions, proved by ICP data. X-ray diffractograms showed two different zeolitic types: MFI and TON. It was observed that when Zn was present in the synthesis gel, pure MFI phases were able to appear. But in his absence, the products were all mixtures of MFI and TON zeolites. It was also possible to distinguish both phases by SEM micrographs, as MFI had brick-like shape and TON appeared as needles. The obtained zeolites were stable until 900°C minimum, as tested by a TG/DTG/DSC experiment. To prove that the chosen OSDA directed these structures, a CHN analysis was performed, resulting in integrity of the molecules inside the zeolitic pores and cavities. Finally, a rationale about the location and conformation of the OSDA was needed to understand these experimental results. So, it was

  16. Direct modulation of T-box riboswitch-controlled transcription by protein synthesis inhibitors.

    Science.gov (United States)

    Stamatopoulou, Vassiliki; Apostolidi, Maria; Li, Shuang; Lamprinou, Katerina; Papakyriakou, Athanasios; Zhang, Jinwei; Stathopoulos, Constantinos

    2017-09-29

    Recently, it was discovered that exposure to mainstream antibiotics activate numerous bacterial riboregulators that control antibiotic resistance genes including metabolite-binding riboswitches and other transcription attenuators. However, the effects of commonly used antibiotics, many of which exhibit RNA-binding properties, on the widespread T-box riboswitches, remain unknown. In Staphylococcus aureus, a species-specific glyS T-box controls the supply of glycine for both ribosomal translation and cell wall synthesis, making it a promising target for next-generation antimicrobials. Here, we report that specific protein synthesis inhibitors could either significantly increase T-box-mediated transcription antitermination, while other compounds could suppress it, both in vitro and in vivo. In-line probing of the full-length T-box combined with molecular modelling and docking analyses suggest that the antibiotics that promote transcription antitermination stabilize the T-box:tRNA complex through binding specific positions on stem I and the Staphylococcal-specific stem Sa. By contrast, the antibiotics that attenuate T-box transcription bind to other positions on stem I and do not interact with stem Sa. Taken together, our results reveal that the transcription of essential genes controlled by T-box riboswitches can be directly modulated by commonly used protein synthesis inhibitors. These findings accentuate the regulatory complexities of bacterial response to antimicrobials that involve multiple riboregulators. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  17. Ethylene glycol assisted low-temperature synthesis of boron carbide powder from borate citrate precursors

    Directory of Open Access Journals (Sweden)

    Rafi-ud-din

    2014-09-01

    Full Text Available B4C powders were synthesized by carbothermal reduction of ethylene glycol (EG added borate citrate precursors, and effects of EG additions (0–50 mol% based on citric acid on the morphologies and yields of synthesized B4C powders were investigated. The conditions most suitable for the preparation of precursor were optimized and optimum temperature for precursor formation was 650 °C. EG additions facilitated low-temperature synthesis of B4C at 1350 °C, which was around 100–300 °C lower temperature compared to that without EG additions. The lowering of synthesis temperature was ascribed to the enlargement of interfacial area caused by superior homogeneity and dispersibility of precursors enabling the diffusion of reacting species facile. The 20% EG addition was optimal with free residual carbon lowered to 4%. For smaller EG additions, the polyhedral and rod-like particles of synthesized product co-existed. With higher EG additions, the morphology of synthesized product was transformed into needle and blade-like structure.

  18. Synthesis of a macromonomer library from high-temperature acrylate polymerization.

    Science.gov (United States)

    Zorn, Anna-Marie; Junkers, Thomas; Barner-Kowollik, Christopher

    2009-12-01

    The auto-initiated high temperature acrylate polymerization represents a versatile route for the synthesis of macromonomer building blocks. Various macromonomers were synthesized via this route based on methyl, ethyl, n-butyl, t-butyl, 2-ethylhexyl, isobornyl and 2-[[(butylamino)carbonyl]oxy]ethyl acrylate. The synthesis requires a temperature of 140 °C and is carried out in a 5 wt.-% solution of hexyl acetate. The macromonomer library is fully characterized via electrospray ionization mass spectrometry (ESI-MS). The amount of macromonomers containing the geminal double bond lies in between 82 and 95%, depending on the monomer type. The achievable molecular weight of the macromonomers is located between 800 and 2 000 g·mol(-1) with a polydispersity of close to 1.6. In addition, it is demonstrated that radical initiators are useful add-ons (to circumvent the inhibition time observed during initiator-free synthesis) without interfering in the actual polymerization as no initiator-fragment containing products are identified via high resolution mass spectrometry. Copyright © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Low temperature synthesis of lamellar transition metal oxides containing surfactant ions

    Energy Technology Data Exchange (ETDEWEB)

    Janauer, G.G.; Chen, R.; Dobley, A.D.; Zavalij, P.Y.; Whittingham, M.S. [State Univ. of New York, Binghamton, NY (United States)

    1997-09-01

    Recently there has been much interest in reacting vanadium oxides hydrothermally with cationic surfactants to form novel layered compounds. A series of new transition metal oxides, however, has also been formed at or near room temperature in open containers. Synthesis, characterization, and proposed mechanisms of formation are the focus of this work. Low temperature reactions of vanadium pentoxide and ammonium (DTA) transition metal oxides with long chain amine surfactants, such as dodecyltrimethylammonium bromide yielded interesting new products many of which are layered phases. DTA{sub 4}H{sub 2}V{sub 10}O{sub 28}{center_dot}8H{sub 2}O, a layered highly crystalline phase, is the first such phase for which a single crystal X-ray structure has been determined. The unit cell for this material was found to be triclinic with space group P {bar 1} and dimensions a = 9.895(1){angstrom}, b = 11.596(1){angstrom}, c = 21.924(1){angstrom}, {alpha} = 95.153(2){degree}, {beta} = 93.778(1){degree}, and {gamma} = 101.360(1){degree}. Additionally, the authors synthesized a dichromate phase and a manganese chloride layered phase, with interlayer spacings of 26.8{angstrom}, and 28.7{angstrom} respectively. The structure, composition, and synthesis of the vanadium compound are described, as well as the synthesis and preliminary characterization of the new chromium and manganese materials.

  20. Facial Sketch Synthesis Using 2D Direct Combined Model-Based Face-Specific Markov Network.

    Science.gov (United States)

    Tu, Ching-Ting; Chan, Yu-Hsien; Chen, Yi-Chung

    2016-08-01

    A facial sketch synthesis system is proposed, featuring a 2D direct combined model (2DDCM)-based face-specific Markov network. In contrast to the existing facial sketch synthesis systems, the proposed scheme aims to synthesize sketches, which reproduce the unique drawing style of a particular artist, where this drawing style is learned from a data set consisting of a large number of image/sketch pairwise training samples. The synthesis system comprises three modules, namely, a global module, a local module, and an enhancement module. The global module applies a 2DDCM approach to synthesize the global facial geometry and texture of the input image. The detailed texture is then added to the synthesized sketch in a local patch-based manner using a parametric 2DDCM model and a non-parametric Markov random field (MRF) network. Notably, the MRF approach gives the synthesized results an appearance more consistent with the drawing style of the training samples, while the 2DDCM approach enables the synthesis of outcomes with a more derivative style. As a result, the similarity between the synthesized sketches and the input images is greatly improved. Finally, a post-processing operation is performed to enhance the shadowed regions of the synthesized image by adding strong lines or curves to emphasize the lighting conditions. The experimental results confirm that the synthesized facial images are in good qualitative and quantitative agreement with the input images as well as the ground-truth sketches provided by the same artist. The representing power of the proposed framework is demonstrated by synthesizing facial sketches from input images with a wide variety of facial poses, lighting conditions, and races even when such images are not included in the training data set. Moreover, the practical applicability of the proposed framework is demonstrated by means of automatic facial recognition tests.

  1. Production of advanced materials by methods of self-propagating high-temperature synthesis

    CERN Document Server

    Tavadze, Giorgi F

    2013-01-01

    This translation from the original Russian book outlines the production of a variety of materials by methods of self-propagating high-temperature synthesis (SHS). The types of materials discussed include: hard, refractory, corrosion and wear-resistant materials, as well as other advanced and speciality materials. The authors address the issue of optimal parameters for SHS reactions occurring during processes involving a preliminary metallothermic reduction stage, and they calculate this using thermodynamic approaches. In order to confirm the effectiveness of this approach, the authors describe experiments focussing on the synthesis of elemental crysalline boron, boron carbides and nitrides. Other parts of this brief include theoretical and experimental results on single-stage production of hard alloys on the basis of titanium and zirconium borides, as well as macrokinetics of degassing and compaciton of SHS-products.This brief is suitable for academics, as well as those working in industrial manufacturing com...

  2. Synthesis of Dense BC3 Phases under High-Pressure and High-Temperature

    Science.gov (United States)

    Zinin, P.; Ming, L.; Acosta, T.; Jia, R.; Hellebrand, E.; Ishii, H.

    2010-12-01

    The finding of the new diamond-like B-C phases is of fundamental importance. These phases are potential high-temperature superconductors and their development is important for understanding the nature of high-temperature superconductivity (Moussa, Cohen, Phys. Rev. B, 77, 064518 2008). They will shed light on the nature of the bonding of the boron atoms in a diamond-like structure. Recently, theoretical simulations of pressure- and temperature-induced phase transition in the B-C system demonstrated that the incorporation of B atoms into a diamond structure should not lead to a drastic distortion of the cubic cell of a diamond (Lowther, J. Phys. Condense Matter. 17, 3221, 2005). In this report we present data on the synthesis of new dense phases cubic BC3 (c-BC3) phase from graphitic BC3 phase (g-BC3) phase under high pressure and high temperature. Two graphitic polycrystalline BCx samples were compressed in a diamond-anvil cell to about 24 GPa and 45 GPa, respectively, and then were laser-heated to ~2000 K. After quenching, each sample was decompressed gradually stepwise to the atmospheric pressure. Synchrotron-based X-ray diffraction patterns were taken before and after the laser-heating, and also at each pressure step-down. The experimental data showed that two new phases were synthesized: (a) an orthorhombic phase with a0 = 3.74 Å, b0 = 3.24 Å, c0=4.25 Å; and (b) a cubic phase with a0 = 3.587Å recovered from 24 GPa and 44 GPa, respectively. The zero-pressure lattice parameter of the cubic phase obtained in this study is larger than that of diamond (i.e., a0=3.5667 Å, ASTM # 6-0675), which is consistent with theoretical prediction The micro-Raman measurements were directly performed on the new phases. The Raman spectra excited by a green (Nd-YAG, 532-nm) laser were taken with a confocal Raman system (WiTec alpha300). The Raman spectrum of the c-BC3 phase is similar to that of diamond-like BC3 phase (Zinin et al., J. Raman Spectrosc., 38, 1362, 2007) with a

  3. Direct observation of temperature-driven magnetic symmetry transitions by vectorial resolved MOKE magnetometry

    Science.gov (United States)

    Cuñado, Jose Luis F.; Pedrosa, Javier; Ajejas, Fernando; Perna, Paolo; Miranda, Rodolfo; Camarero, Julio

    2017-10-01

    Angle- and temperature-dependent vectorial magnetometry measurements are necessary to disentangle the effective magnetic symmetry in magnetic nanostructures. Here we present a detailed study on an Fe(1 0 0) thin film system with competing collinear biaxial (four-fold symmetry) and uniaxial (two-fold) magnetic anisotropies, carried out with our recently developed full angular/broad temperature range/vectorial-resolved magneto-optical Kerr effect magnetometer, named TRISTAN. The data give direct views on the angular and temperature dependence of the magnetization reversal pathways, from which characteristic axes, remanences, critical fields, domain wall types, and effective magnetic symmetry are obtained. In particular, although the remanence shows four-fold angular symmetry for all investigated temperatures (15 K-400 K), the critical fields show strong temperature and angular dependencies and the reversal mechanism changes for specific angles at a given (angle-dependent) critical temperature, showing signatures of an additional collinear two-fold symmetry. This symmetry-breaking is more relevant as temperature increases to room temperature. It originates from the competition between two anisotropy contributions with different symmetry and temperature evolution. The results highlight the importance of combining temperature and angular studies, and the need to look at different magnetic parameters to unravel the underlying magnetic symmetries and temperature evolutions of the symmetry-breaking effects in magnetic nanostructures.

  4. DISY. The direct synthesis of hydrogen peroxide, a bridge for innovative applications

    Energy Technology Data Exchange (ETDEWEB)

    Buzzoni, R.; Perego, C. [Eni S.p.A., Novara (Italy). Research Center for Non-Conventional Energies

    2011-07-01

    Hydrogen peroxide is largely recognized as the green oxidant of choice for future sustainable processes. The current industrial production still goes through the old anthraquinone process, a complex, two-step process suffering from a low specific productivity. Following the development of TS-1/H{sub 2}O{sub 2} based selective oxidation processes e.g. propylene epoxidation, cyclohexanone ammoximation and the new benzene direct oxidation to phenol, there has been an incentive for the development of a new technology, simpler and with better economics. DISY process, based on direct synthesis of hydrogen peroxide from hydrogen and oxygen, is highly suitable to the design of integrated selective oxidation processes as well as for production of commercial-grade high concentration aqueous hydrogen peroxide solutions. Catalyst and process development up to pilot scale are described. (orig.)

  5. Synthesis of gold hexagonal bipyramids directed by planar-twinned silver triangular nanoprisms.

    Science.gov (United States)

    Personick, Michelle L; Langille, Mark R; Wu, Jinsong; Mirkin, Chad A

    2013-03-13

    The direct growth of planar-twinned Au nanoparticles (NPs) in high yield remains a challenge in shape-controlled NP synthesis largely because suitable planar-twinned seeds for Au NP growth have not been identified to date. Herein we describe the use of planar-twinned Ag triangular nanoprisms as a means to dictate Au NP twin structure. In a one-pot process, the Ag triangular nanoprisms first undergo oxidative Au replacement, forming Ag-Au alloy nanoframes and concomitantly releasing Ag(+) into solution, which then directs subsequent Au NP growth through an underpotential deposition process. The planar-twinned structure of the initial Ag nanoprism is maintained throughout particle growth. Using this method, we have successfully synthesized Au hexagonal bipyramids in high yield for the first time.

  6. Palladium-tin catalysts for the direct synthesis of H₂O₂ with high selectivity.

    Science.gov (United States)

    Freakley, Simon J; He, Qian; Harrhy, Jonathan H; Lu, Li; Crole, David A; Morgan, David J; Ntainjua, Edwin N; Edwards, Jennifer K; Carley, Albert F; Borisevich, Albina Y; Kiely, Christopher J; Hutchings, Graham J

    2016-02-26

    The direct synthesis of hydrogen peroxide (H2O2) from H2 and O2 represents a potentially atom-efficient alternative to the current industrial indirect process. We show that the addition of tin to palladium catalysts coupled with an appropriate heat treatment cycle switches off the sequential hydrogenation and decomposition reactions, enabling selectivities of >95% toward H2O2. This effect arises from a tin oxide surface layer that encapsulates small Pd-rich particles while leaving larger Pd-Sn alloy particles exposed. We show that this effect is a general feature for oxide-supported Pd catalysts containing an appropriate second metal oxide component, and we set out the design principles for producing high-selectivity Pd-based catalysts for direct H2O2 production that do not contain gold. Copyright © 2016, American Association for the Advancement of Science.

  7. Supramolecular self-assembled molecules as organic directing agent for synthesis of zeolites.

    Science.gov (United States)

    Corma, Avelino; Rey, Fernando; Rius, Jordi; Sabater, Maria J; Valencia, Susana

    2004-09-16

    Solid materials with uniform micropores, such as zeolites, can act as selective catalysts and adsorbents for molecular mixtures by separating those molecules small enough to enter their pores while leaving the larger molecules behind. Zeolite A is a microporous material with a high void volume. Despite its widespread industrial use in, for example, molecular separations and in detergency, its capability as a petroleum-refining material is limited owing to its poor acid-catalytic activity and hydrothermal stability, and its low hydrophobicity. These characteristics are ultimately a consequence of the low framework Si/Al ratio (normally around one) and the resulting high cationic fraction within the pores and cavities. Researchers have modified the properties of type-A zeolites by increasing the Si/Al compositions up to a ratio of three. Here we describe the synthesis of zeolite A structures exhibiting high Si/Al ratios up to infinity (pure silica). We synthesize these materials, named ITQ-29, using a supramolecular organic structure-directing agent obtained by the self-assembly, through pi-pi type interactions, of two identical organic cationic moieties. The highly hydrophobic pure-silica zeolite A can be used for hydrocarbon separations that avoid oligomerization reactions, whereas materials with high Si/Al ratios give excellent shape-selective cracking additives for increasing propylene yield in fluid catalytic cracking operations. We have also extended the use of our supramolecular structure-directing agents to the synthesis of a range of other zeolites.

  8. Spatial height directed microfluidic synthesis of transparent inorganic upconversion nano film

    Science.gov (United States)

    Liu, Xiaoxia; Zhu, Cheng; Liao, Wei; Jin, Junyang; Ni, Yaru; Lu, Chunhua; Xu, Zhongzi

    2017-11-01

    A microfluidic-based synthesis of an inorganic upconversion nano film has been developed with a large area of dense-distributed NaYF4 crystal grains in a silica glass micro-reactor and the film exhibits high transparence, strong upconversion luminescence and robust adhesion with the substrate. The spatial heights of micro-reactors are tuned between 31 and 227 mm, which can regulate flow regimes. The synergistic effect of spatial height and fluid regime is put forward, which influences diffusion paths and assembly ways of different precursor molecules and consequently directs final distributions and morphologies of crystal grains, as well as optical properties due to diversity of surface and thickness of films. The spatial height of 110 mm is advantageous for high transmittance of upconversion film due to the flat surface and appropriate film thickness of 67 nm. The height of 150 mm is in favor of uniform distribution of upconversion fluorescence and achieving the strongest fluorescence due to minimized optical loss. Such a transparent upconversion film with a large area of uniform distribution is promising to promote the application of upconversion materials and spatial height directed microfluidic regime have a certain significance on many microfluidic synthesis.

  9. Room temperature synthesis of high temperature stable lanthanum phosphate–yttria nano composite

    Energy Technology Data Exchange (ETDEWEB)

    Sankar, Sasidharan; Raj, Athira N.; Jyothi, C.K. [Material Sciences and Technology Division, National Institute for Interdisciplinary Science and Technology, Council of Scientific and Industrial Research, Thiruvananthapuram 695019 (India); Warrier, K.G.K., E-mail: wwarrierkgk@yahoo.co.in [Material Sciences and Technology Division, National Institute for Interdisciplinary Science and Technology, Council of Scientific and Industrial Research, Thiruvananthapuram 695019 (India); Padmanabhan, P.V.A. [Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2012-07-15

    Graphical abstract: A facile aqueous sol–gel route involving precipitation–peptization mechanism followed by electrostatic stabilization is used for synthesizing nanocrystalline composite containing lanthanum phosphate and yttria. Highlights: ► A novel lanthanum phosphate–Y{sub 2}O{sub 3} nano composite is synthesized for the first time using a modified facile sol gel process. ► The composite becomes crystalline at 600 °C and X-ray diffraction pattern is indexed for monoclinic LaPO{sub 4} and cubic yttria. ► The composite synthesized was tested up to 1300 °C and no reaction between the phases of the constituents is observed with the morphologies of the phases being retained. -- Abstract: A facile aqueous sol–gel route involving precipitation–peptization mechanism followed by electrostatic stabilization is used for synthesizing nanocrystalline composite containing lanthanum phosphate and yttria. Lanthanum phosphate (80 wt%)–yttria (20 wt%) nano composite (LaPO{sub 4}–20%Y{sub 2}O{sub 3}), has an average particle size of ∼70 nm after heat treatment of precursor at 600 °C. TG–DTA analysis reveals that stable phase of the composite is formed on heating the precursor at 600 °C. The TEM images of the composite show rod shape morphology of LaPO{sub 4} in which yttria is acquiring near spherical shape. Phase identification of the composite as well as the phase stability up to 1300 °C was carried out using X-ray diffraction technique. With the phases being stable at higher temperatures, the composite synthesized should be a potential material for high temperature applications like thermal barrier coatings and metal melting applications.

  10. Effect of seasonal and experimental temperature on de novo synthesis of fatty acids in C. crangon.

    Science.gov (United States)

    Mika, Adriana; Skorkowski, Edward; Stepnowski, Piotr

    2014-01-01

    The intensity of in vivo lipogensis was measured and in this purpose, the radioactivity of incorporation of tritium into fatty acids (FAs) in tissues of C. crangon was determined. De novo synthesis of FAs was five times higher in hepatopancreas than in muscle in summer period but not much higher in autumn. The higher FAs synthesis was recorded at 25 °C, both for hepatopancreas and muscle, and the summer was higher than the autumn in the hepatopancreas and in the muscles of the opposite situation was observed. The higher amounts of SFAs in hepatopancreas from autumn, when in experimental conditions the ambient temperature C. crangon changed from 6 °C to the experimental higher temperature. When content of PUFAn-3 declined dramatically (Autumn 1 h, 25 °C). In contrast, at a lower temperature, the amount of polyunsaturated FAs is much higher than at 25 °C (Autumn 1 h 6 °C).

  11. Control of nanoparticle agglomeration through variation of the time-temperature profile in chemical vapor synthesis

    Science.gov (United States)

    Djenadic, Ruzica; Winterer, Markus

    2017-02-01

    The influence of the time-temperature history on the characteristics of nanoparticles such as size, degree of agglomeration, or crystallinity is investigated for chemical vapor synthesis (CVS). A simple reaction-coagulation-sintering model is used to describe the CVS process, and the results of the model are compared to experimental data. Nanocrystalline titania is used as model material. Titania nanoparticles are generated from titanium-tetraisopropoxide (TTIP) in a hot-wall reactor. Pure anatase particles and mixtures of anatase, rutile (up to 11 vol.%), and brookite (up to 29 vol.%) with primary particle sizes from 1.7 nm to 10.5 nm and agglomerate particle sizes from 24.3 nm to 55.6 nm are formed depending on the particle time-temperature history. An inductively heated furnace with variable inductor geometry is used as a novel system to control the time-temperature profile in the reactor externally covering a large wall temperature range from 873 K to 2023 K. An appropriate choice of inductor geometry, i.e. time-temperature profile, can significantly reduce the degree of agglomeration. Other particle characteristics such as crystallinity are also substantially influenced by the time-temperature profile.

  12. Control of nanoparticle agglomeration through variation of the time-temperature profile in chemical vapor synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Djenadic, Ruzica; Winterer, Markus, E-mail: markus.winterer@uni-due.de [Universität Duisburg-Essen, Nanoparticle Process Technology, Faculty of Engineering and CENIDE (Germany)

    2017-02-15

    The influence of the time-temperature history on the characteristics of nanoparticles such as size, degree of agglomeration, or crystallinity is investigated for chemical vapor synthesis (CVS). A simple reaction-coagulation-sintering model is used to describe the CVS process, and the results of the model are compared to experimental data. Nanocrystalline titania is used as model material. Titania nanoparticles are generated from titanium-tetraisopropoxide (TTIP) in a hot-wall reactor. Pure anatase particles and mixtures of anatase, rutile (up to 11 vol.%), and brookite (up to 29 vol.%) with primary particle sizes from 1.7 nm to 10.5 nm and agglomerate particle sizes from 24.3 nm to 55.6 nm are formed depending on the particle time-temperature history. An inductively heated furnace with variable inductor geometry is used as a novel system to control the time-temperature profile in the reactor externally covering a large wall temperature range from 873 K to 2023 K. An appropriate choice of inductor geometry, i.e. time-temperature profile, can significantly reduce the degree of agglomeration. Other particle characteristics such as crystallinity are also substantially influenced by the time-temperature profile.

  13. Determination of Charge Component Composition in Self-Propagating High-Temperature Synthesis of Intermetallic Compounds

    Science.gov (United States)

    Evtushenko, A. T.; Lebedeva, O. A.; Torbunov, S. S.

    2005-05-01

    A method for determining the component composition of the charge for the self-propagating high-temperature synthesis of intermetallic compounds from the maximum value of the emitted heat in the combustion of thermit, which is required for melting the alloying components, is suggested. The mass composition of the alloying components is determined by solving a closed system of algebraic equations represented by regression equations derived from the results of physical experiment for obtaining specific properties of the intermetallic compound. Theoretical computations are partially confirmed by experimental results.

  14. Liquid phase low temperature method for production of methanol from synthesis gas and catalyst formulations therefor

    Science.gov (United States)

    Mahajan, Devinder

    2005-07-26

    The invention provides a homogenous catalyst for the production of methanol from purified synthesis gas at low temperature and low pressure which includes a transition metal capable of forming transition metal complexes with coordinating ligands and an alkoxide, the catalyst dissolved in a methanol solvent system, provided the transition metal complex is not transition metal carbonyl. The coordinating ligands can be selected from the group consisting of N-donor ligands, P-donor ligands, O-donor ligands, C-donor ligands, halogens and mixtures thereof.

  15. Low-Temperature Synthesis of Actinide Tetraborides by Solid-State Metathesis Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Lupinetti, Anthony J.; Garcia, Eduardo; Abney, Kent D.

    2004-12-14

    The synthesis of actinide tetraborides including uranium tetraboride (UB,), plutonium tetraboride (PUB,) and thorium tetraboride (ThB{sub 4}) by a solid-state metathesis reaction are demonstrated. The present method significantly lowers the temperature required to {approx_equal}850 C. As an example, when UCl{sub 4}, is reacted with an excess of MgB{sub 2}, at 850 C, crystalline UB, is formed. Powder X-ray diffraction and ICP-AES data support the reduction of UCl{sub 3}, as the initial step in the reaction. The UB, product is purified by washing water and drying.

  16. Room temperature synthesis of wurtzite phase nanostructured ZnS and accompanied enhancement in dielectric constant

    Science.gov (United States)

    Virpal, Kumar, J.; Singh, G.; Singh, M.; Sharma, S.; Singh, R. C.

    2017-04-01

    We report the room temperature synthesis of ZnS in the wurtzite phase by using ethylenediamine, which acts as a template as well as a capping agent. With the addition of ethylenediamine, structural transformation in ZnS from cubic to wurtzite phase is observed. This is accompanied by an increase in the real permittivity by an order of 2, and reduction in dielectric loss by a factor of 6 as compared to a sample without ethylenediamine. Thus, suggesting that ethylenediamine capped wurtzite ZnS is more suitable for miniaturied capactive devices.

  17. Temperature and Species Measurements of Combustion Produced by a 9-Point Lean Direct Injector

    Science.gov (United States)

    Tedder, Sarah A.; Hicks, Yolanda R.; Locke, Randy J.

    2013-01-01

    This paper presents measurements of temperature and relative species concentrations in the combustion flowfield of a 9-point swirl venturi lean direct injector fueled with JP-8. The temperature and relative species concentrations of the flame produced by the injector were measured using spontaneous Raman scattering (SRS). Results of measurements taken at four flame conditions are presented. The species concentrations reported are measured relative to nitrogen and include oxygen, carbon dioxide, and water.

  18. A flexible synthesis of 2,3-disubstituted indoles from aminobenzyl phosphonium salts. A direct synthesis of rutaecarpine.

    Science.gov (United States)

    Kraus, George A; Guo, Haitao

    2009-08-07

    The reaction of substituted (2-aminobenzyl)triphenylphosphonium bromides with aromatic aldehydes or alpha,beta-unsaturated aldehydes constitutes a new synthesis of 2,3-disubstitued indoles in high yields. The adduct from 4-oxo-3,4-dihydroquinazoline-2-carbaldehyde was an advanced intermediate in the synthesis of several rutaecarpines.

  19. Direct synthesis of vertically aligned ZnO nanowires on FTO substrates using a CVD method and the improvement of photovoltaic performance

    Science.gov (United States)

    2012-01-01

    In this work, we report a direct synthesis of vertically aligned ZnO nanowires on fluorine-doped tin oxide-coated substrates using the chemical vapor deposition (CVD) method. ZnO nanowires with a length of more than 30 μm were synthesized, and dye-sensitized solar cells (DSSCs) based on the as-grown nanowires were fabricated, which showed improvement of the device performance compared to those fabricated using transferred ZnO nanowires. Dependence of the cell performance on nanowire length and annealing temperature was also examined. This synthesis method provided a straightforward, one-step CVD process to grow relatively long ZnO nanowires and avoided subsequent nanowire transfer process, which simplified DSSC fabrication and improved cell performance. PMID:22673046

  20. Effect of reducing agents on low-temperature synthesis of nanostructured LiFePO4

    Science.gov (United States)

    Kulka, Andrzej; Walczak, Katarzyna; Zając, Wojciech; Molenda, Janina

    2017-09-01

    Simple co-precipitation synthesis procedure yielding nanometric LiFePO4 with enhanced electrochemical properties without any post-synthesis heat treatment is presented. XRD, SEM and TEM analysis of the obtained powders revealed platelet crystallites and well crystalized bulk structure. Effective way of decreasing amount of Fe3+ containing phases by addition of reducing agents (KI, (NH4)2S2O3, glucose and the atmosphere of 5%H2-95%Ar) during low-temperature (107 °C) synthesis is described. The traditional analytical chemistry methods or the Mӧssbauer spectroscopy methods revealed that utilization of selected reducing agents diminished Fe3+ concentration from 25 to 12 at%. The constructed cells with optimized LiFePO4 as a cathode material showed superior electrochemical performances, including high reversible capacity up to 162 mAh/g at C/10 current discharge rate, flat voltage plateau with a value close to 3.45 V vs. Li0/+.

  1. Instant synthesis of gold nanoparticles at room temperature and SERS applications

    Energy Technology Data Exchange (ETDEWEB)

    Britto Hurtado, R. [Departamento de Investigación en Física, Universidad de Sonora, Apdo. Postal 5-88, 83190, Hermosillo, Sonora (Mexico); Cortez-Valadez, M., E-mail: jose.cortez@unison.mx [CONACYT-Departamento de Investigación en Física, Universidad de Sonora, Apdo. Postal 5-88, 83190, Hermosillo, Sonora (Mexico); Ramírez-Rodríguez, L.P. [Departamento de Física, Universidad de Sonora, Apdo. Postal 5-88, 83190, Hermosillo, Sonora (Mexico); Larios-Rodriguez, Eduardo [Departamento de Ingeniería Química y Metalurgia, Universidad de Sonora, Rosales y Luis Encinas S/N, Hermosillo, Sonora (Mexico); Alvarez, Ramón A.B.; Rocha-Rocha, O.; Delgado-Beleño, Y.; Martinez-Nuñez, C.E.; Arizpe-Chávez, H. [Departamento de Investigación en Física, Universidad de Sonora, Apdo. Postal 5-88, 83190, Hermosillo, Sonora (Mexico); Hernández-Martínez, A.R. [Centro de Física Aplicada y Tecnología Avanzada (CFATA), Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro C.P. 76130 (Mexico); Flores-Acosta, M. [Departamento de Investigación en Física, Universidad de Sonora, Apdo. Postal 5-88, 83190, Hermosillo, Sonora (Mexico)

    2016-08-06

    Nowadays, gold nanoparticles (AuNps) can be used in a variety of applications, thus efficient methods to produce them are necessary. Several methods have been proposed in this area, but NPs production time is one limitation of these approaches. In this study, we propose a high competitive method to synthesize gold colloidal nanoparticles, instantaneously, using no-toxic reducing agents. These substances allow the instantaneous synthesis at room temperature, even without magnetic stirrers, ovens or ultrasonic baths. Optic analysis showed two absorption bands, associated with surface Plasmon as function of HAuCl{sub 4} concentration. The nanoparticles synthesized have a 10–20 nm size, seen by the transmission electron microscopy (TEM). Therefore, it was possible to obtain several geometric patterns of AuNps, and the synthesis was performed reducing significantly processing time. Additionally, Mie and Fuchs theories were used to predict the location of the absorption bands linked to the plasmon surface in gold nanoparticles. The Surface Enhanced Raman Spectroscopy (SERS) effect was analyzed considering natural zeolite (Chabazite) as analyte, in order to determinate its possible application in soil analysis. - Highlights: • Cubic and spherical morphologies in AuNp. • Surface plasmon prediction in cubic and spherical AuNp. • Instant synthesis of AuNp. • SERS applications in soil analysis.

  2. Temperature dependence of direct current conductivity in Ag-ED20 nanocomposite films

    Science.gov (United States)

    Novikov, G. F.; Rabenok, E. V.; Bogdanova, L. M.; Irzhak, V. I.

    2017-10-01

    The effect of silver nanoparticles (NPs) in the concentration range of ≤0.8 wt % have on direct current conductivity σdc of Ag-ED20 nanocomposite is studied by method of broadband dielectric spectroscopy (10-2-105 Hz) method of broadband dielectric spectroscopy. It is found that temperature dependence σdc consists of two sections: above the glass transition temperature ( T g), the dependence corresponds to the empirical Vogel-Fulcher-Tammann law (Vogel temperature T 0 does not depend on the NP concentration); below T g, the dependence is Arrhenius with activation energy E a ≈ 1.2 eV. In the region where T > T g, the σdc value grows along with NP concentration. It is concluded that the observed broken form of the temperature dependence is apparently due to a change in the conduction mechanism after the freezing of ion mobility at temperatures below T g.

  3. Numerical Analysis on the Effects of Initial Temperature of the PCM in Transient Direct Contact Melting

    Science.gov (United States)

    Saito, Akio; Kumano, Hiroyuki; Okawa, Seiji; Ohta, Shinro

    The effects of the initial temperature of the solid PCM on a transient direct contact melting were invesigated, analytically. Four types of boundary conditions, that is, the constant temperature at the top, the constant heat flux at the top, the constant heat flux at the bottom, and the constant heat transfer coefficient and the constant temperature of the medium at the bottom of the heating plate, respectively, were examined. The effects of the initial temperature for each boundary condition were investigated through the transient process of the direct contact melting, where the heat transfer phenomena within the liquid film formed between the solid and the heating plate was unsteady, for the case of initial temperature lower than the melting point. It was found, as the results, that the time required until to approach the quasi-steady state and the melting speed at the time depended seriously on the initial temperature. It was understood, at the same time, that the heat flux flowing into the solid was not negligible, even in the quasi-steady state. Then, effects of the non-dimensional parameters, appearing in relation to the initial temperature variation of the solid, were examined, qualitatively.

  4. Microreactor with integrated temperature control for the synthesis of CdSe nanocrystals.

    Science.gov (United States)

    Gómez-de Pedro, Sara; Martínez-Cisneros, Cynthia S; Puyol, Mar; Alonso-Chamarro, Julián

    2012-05-08

    The recent needs in the nanosciences field have promoted the interest towards the development of miniaturized and highly integrated devices able to improve and automate the current processes associated with efficient nanomaterials production. Herein, a green tape based microfluidic system to perform high temperature controlled synthetic reactions of nanocrystals is presented. The device, which integrates both the microfluidics and a thermally controlled platform, was applied to the automated and continuous synthesis of CdSe quantum dots. Since temperature can be accurately regulated as required, size-controlled and reproducible quantum dots could be obtained by regulating this parameter and the molar ratio of precursors. The obtained nanocrystals were characterized by UV-vis and fluorescence spectrophotometry. The band width of the emission peaks obtained indicates a narrow size distribution of the nanocrystals, which confirms the uniform temperature profile applied for each synthetic process, being the optimum temperature at 270 °C (full width at half maximum = 40 nm). This approach allows a temperature controlled, easy, low cost and automated method to produce quantum dots in organic media, enhancing its application from laboratory-scale to pilot-line scale processes.

  5. Remarkable lowering in the synthesis temperature of LiMn2O4via citrate solution-gel synthesis facilitated by ethanol.

    Science.gov (United States)

    Maino, G; Carleer, R; Marchal, W; Bonneux, G; Hardy, A; Van Bael, M K

    2017-11-07

    LiMn2O4 (LMO) is interesting from the viewpoint of its energy storage applications as it is a cathode in lithium ion batteries (LIB), which contains no rare, toxic or expansive elements, while it provides a high theoretical capacity (148 mA h g-1) at a reasonable voltage (4 V region) and a higher thermal stability compared to cobalt based cathodes and has a good rechargeability and cycling stability due to its spinel structure. Low temperature synthesis routes for cathode materials are currently gaining attention, in order to decrease the ecological footprint of the final LIB. Here, the crystallization temperature of LMO by a citrate based solution-gel synthesis was significantly lowered, to as low as 250 °C by the addition of ethanol to the precursor. The role of ethanol in this synthesis process was explored. It was found to lead to a considerable increase in the oxidation rate of the redox couple Mn2+/Mn3+, a lowering of the precursor decomposition temperature by 200 °C, besides a drastic decrease in the crystallization temperature (reaching 250 °C). Moreover, the main cause was identified to be an esterification reaction of ethanol with the carboxylic acid in the precursor complexes, taking place before the oxide formation. The insights obtained strengthen the knowledge regarding citrato-Mn2+/Mn3+ complexes present in aqueous solution-gel synthesis routes and are relevant for the preparation of various manganese containing oxides. Moreover, the precursor developed opens up a new possibility for the low temperature synthesis of LMO powders and thin films for application in LIB. In the case of thin film batteries, the low temperature processing provides compatibility with other materials in the thin film battery stack, avoiding undesired oxidations or interfacial reactions.

  6. Low Temperature Salt Flux Synthesis of Multiple Phases of Monometallic and Bimetallic Carbide Nanomaterials for Catalysis

    Science.gov (United States)

    Schmuecker, Samantha M.

    Nanostructured metal carbides are of particular interest because of their potential as high surface area, low cost catalysts specifically for hydrogen evolution reaction (HER). By taking advantage of a salt flux synthesis method, multiple carbide compounds have been synthesized at low temperatures providing a pathway to nano-sized materials. To better understand the reaction mechanism, vanadium carbide (V8C7) synthesis was monitored by quenching samples at 100 °C intervals and analyzed by multiple spectroscopic methods (Chapter 2). The synthesis method was further extended to form several single metal carbide compounds including some systems that form multiple phases with different compositions and crystal structures that are not as well studied due to their limited synthetic approaches and instability. As an example, Chromium carbide forms five different crystal structures including three common phases, Cr3C2, Cr7C3, and Cr 23C6, and two less studied phases, Cr2C and CrC (Chapter 3). Bimetallic carbides are even more challenging to synthesize both as bulk and nano-sized materials and thus are rarely studied as alternative catalysts. The major synthetic challenges for bimetallic carbides are phase separation of monometallic species and limited composition control over the bimetallic compounds. The low temperature nature of this reaction method allows access to greater composition control and single phase products. As an example of the synthesis process and combining multiple metals, several bimetallic systems were investigated using this method including Ta-Nb-C, Nb-Cr-C, and Ta-Cr-C. Ta-Nb-C readily forms a solid solution because both TaC and NbC form a rock salt crystal structure while Nb-Cr-C and Ta-Cr-C both have very limited Cr solubility due to the presence of different crystal structures formed by Cr-C (Chapter 4). Cr-Fe-C and Cr-Mn-C form different crystal structure carbides. Cr-C, Mn-C, and Fe-C all make M7C3 and M23C 6 structures. M7C3 is an orthorhombic

  7. Catalytic enantioselective synthesis of atropisomeric biaryls by a cation-directed O-alkylation

    Science.gov (United States)

    Jolliffe, John D.; Armstrong, Roly J.; Smith, Martin D.

    2017-06-01

    Axially chiral biaryls, as exemplified by 1,1‧-bi-2-naphthol (BINOL), are key components of catalysts, natural products and medicines. These materials are synthesized conventionally in enantioenriched form through metal-mediated cross coupling, de novo construction of an aromatic ring, point-to-axial chirality transfer or an atropselective transformation of an existing biaryl. Here, we report a highly enantioselective organocatalytic method for the synthesis of atropisomeric biaryls by a cation-directed O-alkylation. Treatment of racemic 1-aryl-2-tetralones with a chiral quinidine-derived ammonium salt under basic conditions in the presence of an alkylating agent leads to atropselective O-alkylation with e.r. up to 98:2. Oxidation with DDQ gives access to C2-symmetric and non-symmetric BINOL derivatives without compromising e.r. We propose that the chiral ammonium counterion differentiates between rapidly equilibrating atropisomeric enolates, leading to highly atropselective O-alkylation. This dynamic kinetic resolution process offers a general approach to the synthesis of enantioenriched atropisomeric materials.

  8. Direct Synthesis of Large-Area 2D Mo2C on In Situ Grown Graphene.

    Science.gov (United States)

    Geng, Dechao; Zhao, Xiaoxu; Chen, Zhongxin; Sun, Weiwei; Fu, Wei; Chen, Jianyi; Liu, Wei; Zhou, Wu; Loh, Kian Ping

    2017-09-01

    As a new member of the MXene group, 2D Mo 2 C has attracted considerable interest due to its potential application as electrodes for energy storage and catalysis. The large-area synthesis of Mo 2 C film is needed for such applications. Here, the one-step direct synthesis of 2D Mo 2 C-on-graphene film by molten copper-catalyzed chemical vapor deposition (CVD) is reported. High-quality and uniform Mo 2 C film in the centimeter range can be grown on graphene using a Mo-Cu alloy catalyst. Within the vertical heterostructure, graphene acts as a diffusion barrier to the phase-segregated Mo and allows nanometer-thin Mo 2 C to be grown. Graphene-templated growth of Mo 2 C produces well-faceted, large-sized single crystals with low defect density, as confirmed by scanning transmission electron microscopy (STEM) measurements. Due to its more efficient graphene-mediated charge-transfer kinetics, the as-grown Mo 2 C-on-graphene heterostructure shows a much lower onset voltage for hydrogen evolution reactions as compared to Mo 2 C-only electrodes. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Platinum-modulated cobalt nanocatalysts for low-temperature aqueous-phase Fischer-Tropsch synthesis.

    Science.gov (United States)

    Wang, Hang; Zhou, Wu; Liu, Jin-Xun; Si, Rui; Sun, Geng; Zhong, Meng-Qi; Su, Hai-Yan; Zhao, Hua-Bo; Rodriguez, Jose A; Pennycook, Stephen J; Idrobo, Juan-Carlos; Li, Wei-Xue; Kou, Yuan; Ma, Ding

    2013-03-13

    Fischer-Tropsch synthesis (FTS) is an important catalytic process for liquid fuel generation, which converts coal/shale gas/biomass-derived syngas (a mixture of CO and H2) to oil. While FTS is thermodynamically favored at low temperature, it is desirable to develop a new catalytic system that could allow working at a relatively low reaction temperature. In this article, we present a one-step hydrogenation-reduction route for the synthesis of Pt-Co nanoparticles (NPs) which were found to be excellent catalysts for aqueous-phase FTS at 433 K. Coupling with atomic-resolution scanning transmission electron microscopy (STEM) and theoretical calculations, the outstanding activity is rationalized by the formation of Co overlayer structures on Pt NPs or Pt-Co alloy NPs. The improved energetics and kinetics from the change of the transition states imposed by the lattice mismatch between the two metals are concluded to be the key factors responsible for the dramatically improved FTS performance.

  10. Synthesis and characterization of Ni–Cu alloy nanoparticles with a tunable Curie temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ferk, Gregor [Faculty of Chemistry and Chemical Engineering, University of Maribor (Slovenia); Stergar, Janja [Faculty of Medicine, University of Maribor (Slovenia); Makovec, Darko [Department for Materials Synthesis, Jožef Stefan Institute, Ljubljana (Slovenia); Hamler, Anton [Faculty of Electrical Engineering and Computer Science, University of Maribor (Slovenia); Jagličić, Zvonko [Institute of Mathematics, Physics and Mechanics and Faculty of Civil and Geodetic Engineering, University of Ljubljana (Slovenia); Drofenik, Miha [Faculty of Chemistry and Chemical Engineering, University of Maribor (Slovenia); Department for Materials Synthesis, Jožef Stefan Institute, Ljubljana (Slovenia); Ban, Irena [Faculty of Chemistry and Chemical Engineering, University of Maribor (Slovenia); Center of Excellence NAMASTE, Ljubljana (Slovenia)

    2015-11-05

    A series of nickel–copper alloy magnetic nanoparticles with a range of Curie points from 51 °C to 63 °C were prepared by the reduction of intimately mixed nickel and copper oxides in a silica matrix using the sol–gel method. The silica matrix was subsequently removed with an etching solution, assisted by sonication. The alloy nanoparticles were characterized using X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA/SDTA), thermomagnetic analysis (TMA), transmission electron microscopy (TEM), magnetic measurements (SQUID, vibrating-sample magnetometer) and specific absorption rate measurements (SAR). The synthesized nanoparticles show a size in the range 15–20 nm, exhibited superparamagnetic behavior with a blocking temperature (T{sub B}) of approximately 135 K and a room-temperature magnetization of 3–9 emu/g, depending on the composition. The nanoparticles showed a relatively high effective anisotropy constant (K{sub eff}) and a significant heating ability in an alternating magnetic field. The synthesis method is straightforward and allows the preparation of homogeneous Ni–Cu alloy nanoparticles with a relatively narrow particle size distribution. - Highlights: • Straightforward so-gel synthesis of homogeneous Ni–Cu alloy nanoparticles. • Narrow particle size distribution and controlled Curie point. • Applications in “self-regulating magnetic fluid hyperthermia”. • Heating efficiency of nanoparticles as a function of composition and size.

  11. Simple mass production of zinc oxide nanostructures via low-temperature hydrothermal synthesis

    Science.gov (United States)

    Ghasaban, Samaneh; Atai, Mohammad; Imani, Mohammad

    2017-03-01

    The specific properties of zinc oxide (ZnO) nanoparticles have attracted much attention within the scientific community as a useful material for biomedical applications. Hydrothermal synthesis is known as a useful method to produce nanostructures with certain particle size and morphology however, scaling up the reaction is still a challenging task. In this research, large scale hydrothermal synthesis of ZnO nanostructures (60 g) was performed in a 5 l stainless steel autoclave by reaction between anionic (ammonia or sodium hydroxide) and cationic (zinc acetate dehydrate) precursors in low temperature. Hydrothermal reaction temperature and time were decreased to 115 °C and 2 or 6 h. In batch repetitions, the same morphologies (plate- and needle-like) with reproducible particle size were obtained. The nanostructures formed were analyzed by powder x-ray diffraction, Fourier-transform infrared spectroscopy, energy dispersive x-ray analysis, scanning electron microscopy and BET analysis. The nanostructures formed were antibacterially active against Staphylococcus aureus.

  12. Tuning of PID controllers for integrating systems using direct synthesis method.

    Science.gov (United States)

    Anil, Ch; Padma Sree, R

    2015-07-01

    A PID controller is designed for various forms of integrating systems with time delay using direct synthesis method. The method is based on comparing the characteristic equation of the integrating system and PID controller with a filter with the desired characteristic equation. The desired characteristic equation comprises of multiple poles which are placed at the same desired location. The tuning parameter is adjusted so as to achieve the desired robustness. Tuning rules in terms of process parameters are given for various forms of integrating systems. The tuning parameter can be selected for the desired robustness by specifying Ms value. The proposed controller design method is applied to various transfer function models and to the nonlinear model equations of jacketed CSTR to show its effectiveness and applicability. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

  13. Mergers and acquisitions: A synthesis of theories and directions for future research

    Directory of Open Access Journals (Sweden)

    Wissal Ben Letaifa

    2017-02-01

    Full Text Available The purpose of this paper is to review a synthesis of theories and empirical studies dealing with the mergers and acquisitions in the recent decay in an attempt to provide directions for future research. The review focuses on four main streams including: first, the motives for mergers-acquisitions; which are the strategic profits, the overconfidence of managers and the desire to create a big empire resulting from merger. From second, corporate characteristics of firms that did merger or acquisition; third, the economic consequences of the operation of merger and acquisition and finally; fourth, the implication on the market with the impact of merger on the value of the firm. We think that this article can give another idea about the information disclosed by any company choosing to merge and can be analyzed by practitioners by giving them the theoretical background of the merger and acquisition problem.

  14. Direct synthesis of linear trinuclear M2IIMn complexes with acetate and NN donor ligands

    Science.gov (United States)

    Nahorna, Oksana V.; Makhankova, Valeria G.; Kokozay, Vladimir N.; Omelchenko, Iryna V.; Dyakonenko, Viktoriya V.; Shishkin, Oleg V.; Jezierska, Julia

    2013-04-01

    Two novel heterometallic complexes with general formula [M2Mn(OAc)6L2], where M = Cd (1), Cu (2) and L = 2,2'-bipyridyl (bpy) for (1), 1,10-phenanthroline (phen) for (2), were obtained using "direct synthesis" approach. Trinuclear molecular structure of the complexes was determined by single crystal X-ray analysis. EPR studies of 2 indicate that the coordination environment in Cu(II) equatorial plane remains unchanged in solution as compared to the initial compound. Due to low volatility of phen the products of its decomposition probably remain on the surface of metal oxides and, therefore, in contrary to previously studied bpy-containing complexes, the compounds with phen are not suitable precursors for binary oxides preparation.

  15. An effective low-temperature solution synthesis of Co-doped [0001]-oriented ZnO nanorods

    OpenAIRE

    Alnoor, Hatim; Savoyant, Adrien; Liu, Xianjie; Pozina, Galia; Willander, Magnus; Nur, Omer

    2017-01-01

    We demonstrate an efficient possibility to synthesize vertically aligned pure zinc oxide (ZnO) and Co-doped ZnO nanorods (NRs) using the low-temperature aqueous chemical synthesis (90 degrees C). Two different mixing methods of the synthesis solutions were investigated for the Co-doped samples. The synthesized samples were compared to pure ZnO NRs regarding the Co incorporation and crystal quality. Electron paramagnetic resonance (EPR) measurements confirmed the substitution of Co2+ inside th...

  16. Synthesis and crystal structures of gold nanowires with Gemini surfactants as directing agents.

    Science.gov (United States)

    Xu, Feng; Hou, Hao; Gao, Zhinong

    2014-12-15

    The preparation of crystalline gold nanowires (NWs) by using gemini surfactants as directing agents through a three-step seed-mediated method is reported. Unlike the nanorods with relatively low aspect ratios (typically below 20) obtained by using cetyltrimethylammonium bromide as a directing agent, the NWs obtained in this investigation can reach up to 4.4 μm, and the largest aspect ratio is calculated to be 210. For this, each of seven different gemini surfactants are utilized as directing agents, and the length and/or aspect ratio of the NWs can be tuned by varying the hydrocarbon chain lengths of the gemini surfactants. Both single and twinned crystalline structures are elucidated by selected-area electron diffraction and high-resolution transmission electron microscopy studies. The use of gemini surfactants not only advances the synthesis of gold nanostructures, but improves the understanding of the growth mechanism for seed-mediated growth. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Direct Observation of Field and Temperature Induced Domain Replication in Dipolar Coupled Perpendicular Anisotropy Films

    Energy Technology Data Exchange (ETDEWEB)

    Hauet, T.; Gunther, C.M.; Pfau, B.; Eisebitt, S.; Fischer, P.; Rick, R. L.; Thiele, J.-U.; Hellwig, O.; Schabes, M.E.

    2007-07-01

    Dipolar interactions in a soft/Pd/hard [CoNi/Pd]{sub 30}/Pd/[Co/Pd]{sub 20} multilayer system, where a thick Pd layer between two ferromagnetic units prevents direct exchange coupling, are directly revealed by combining magnetometry and state-of-the-art layer resolving soft x-ray imaging techniques with sub-100-nm spatial resolution. The domains forming in the soft layer during external magnetic field reversal are found to match the domains previously trapped in the hard layer. The low Curie temperature of the soft layer allows varying its intrinsic parameters via temperature and thus studying the competition with dipolar fields due to the domains in the hard layer. Micromagnetic simulations elucidate the role of [CoNi/Pd] magnetization, exchange, and anisotropy in the duplication process. Finally, thermally driven domain replication in remanence during temperature cycling is demonstrated.

  18. Facile Synthesis of Catalytic AuPd Nanoparticles within Capillary Microreactors Using Polyelectrolyte Multilayers for the Direct Synthesis of H2O2.

    Science.gov (United States)

    Kanungo, Shamayita; Paunovic, Violeta; Schouten, Jaap C; Neira D'Angelo, M Fernanda

    2017-10-11

    Microreactors present innovative solutions for problems pertaining to conventional reactors and therefore have seen successful application in several industrial processes. Yet, its application in heterogeneously catalyzed gas-liquid reactions has been challenging, mainly due to the lack of an easy and flexible methodology for catalyst incorporation inside these reactors. Herein, we report a facile technique for obtaining small (synthesis condition gives easy control over metal loading, without compromising on particle size. Both monometallic (Au and Pd) and bimetallic (AuPd) nanoparticles were successfully obtained using this technique. Finally, these catalytic microreactors were found to exhibit exceptional activity for the direct synthesis of hydrogen peroxide from H2 and O2.

  19. Large scale synthesis and formation mechanism of silver nanoparticles in solid-state reactions at ambient temperature

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Aiqin, E-mail: zhangaiqin@zzuli.edu.cn [State Laboratory of Surface and Interface Science and Technology, Henan Collaborative Innovation Center of Environmental Pollution Control and Ecological Restoration, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Tian, Yakun; Xiao, Yuanhua; Sun, Yuan [State Laboratory of Surface and Interface Science and Technology, Henan Collaborative Innovation Center of Environmental Pollution Control and Ecological Restoration, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Li, Feng [State Laboratory of Surface and Interface Science and Technology, Henan Collaborative Innovation Center of Environmental Pollution Control and Ecological Restoration, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); American Advanced Nanotechnology, Houston, TX 77459 (United States)

    2015-07-15

    Highlights: • AgNPs were prepared by solid state reaction at ambient temperature. • Only silver nitrate and ascorbic acid were needed in this reaction. • The size of the AgNPs can be tuned conveniently. • Formation mechanism of the AgNPs was investigated. - Abstract: A one-step strategy for preparing Ag nanoparticles (AgNPs) on large scale is demonstrated successfully, based on solid-state reactions at ambient temperature. The environmentally friendly synthesis can be achieved by simply grinding AgNO{sub 3} and ascorbic acid (AA) for about 30 min without adding any solvent and organic protectors. The size of AgNPs can be readily controlled by adjusting the reaction parameters such as AgNO{sub 3}/AA molar ratio and reaction time. The nanostructures of AgNPs and their formation mechanism have been also investigated with XRD, FTIR, FESEM, HRTEM and HPLC–MS. It was found that AA can reduce Ag{sup +} into Ag{sup 0} to form AgNPs directly in accompanying with its first oxidation into 2,3-diketogulonic acid (2,3-DKG) and then a series of fragmentary species of 2,3-DKG.

  20. UV-B light contributes directly to the synthesis of chiloglottone floral volatiles

    Science.gov (United States)

    Amarasinghe, Ranamalie; Poldy, Jacqueline; Matsuba, Yuki; Barrow, Russell A.; Hemmi, Jan M.; Pichersky, Eran; Peakall, Rod

    2015-01-01

    Background and Aims Australian sexually deceptive Chiloglottis orchids attract their specific male wasp pollinators by means of 2,5-dialkylcyclohexane-1,3-diones or ‘chiloglottones’, representing a newly discovered class of volatiles with unique structures. This study investigated the hypothesis that UV-B light at low intensities is directly required for chiloglottone biosynthesis in Chiloglottis trapeziformis. Methods Chiloglottone production occurs only in specific tissue (the callus) of the labellum. Cut buds and flowers, and whole plants with buds and flowers, sourced from the field, were kept in a growth chamber and interactions between growth stage of the flowers and duration and intensity of UV-B exposure on chiloglottone production were studied. The effects of the protein synthesis inhibitor cycloheximide were also examined. Key Results Chiloglottone was not present in buds, but was detected in buds that were manually opened and then exposed to sunlight, or artificial UV-B light for ≥5 min. Spectrophotometry revealed that the sepals and petals blocked UV-B light from reaching the labellum inside the bud. Rates of chiloglottone production increased with developmental stage, increasing exposure time and increasing UV-B irradiance intensity. Cycloheximide did not inhibit the initial production of chiloglottone within 5 min of UV-B exposure. However, inhibition of chiloglottone production by cycloheximide occurred over 2 h of UV-B exposure, indicating a requirement for de novo protein synthesis to sustain chiloglottone production under UV-B. Conclusions The sepals and petals of Chiloglottis orchids strongly block UV-B wavelengths of light, preventing chiloglottone production inside the bud. While initiation of chiloglottone biosynthesis requires only UV-B light, sustained chiloglottone biosynthesis requires both UV-B and de novo protein biosynthesis. The internal amounts of chiloglottone in a flower reflect the interplay between developmental stage

  1. A working hypothesis for broadening framework types of zeolites in seed-assisted synthesis without organic structure-directing agent.

    Science.gov (United States)

    Itabashi, Keiji; Kamimura, Yoshihiro; Iyoki, Kenta; Shimojima, Atsushi; Okubo, Tatsuya

    2012-07-18

    Recent research has demonstrated a new synthesis route to useful zeolites such as beta, RUB-13, and ZSM-12 via seed-assisted, organic structure-directing agent (OSDA)-free synthesis, although it had been believed that these zeolites could be essentially synthesized with OSDAs. These zeolites are obtained by adding seeds to the gels that otherwise yield other zeolites; however, the underlying crystallization mechanism has not been fully understood yet. Without any strategy, it is unavoidable to employ a trial-and-error procedure for broadening zeolite types by using this synthesis method. In this study, the effect of zeolite seeds with different framework structures is investigated to understand the crystallization mechanism of zeolites obtained by the seed-assisted, OSDA-free synthesis method. It has been found that the key factor in the successful synthesis of zeolites in the absence of OSDA is the common composite building unit contained both in the seeds and in the zeolite obtained from the gel after heating without seeds. A new working hypothesis for broadening zeolite types by the seed-assisted synthesis without OSDA is proposed on the basis of the findings of the common composite building units in zeolites. This hypothesis enables us to design the synthesis condition of target zeolites. The validity of the hypothesis is experimentally tested and verified by synthesizing several zeolites including ECR-18 in K-aluminosilicate system.

  2. Influence of the temperature in the electrochemical synthesis of cobalt ferrites nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Mazario, E. [Departamento de Quimica Fisica Aplicada, Facultad de Ciencias, Universidad Autonoma de Madrid, UAM, C/Francisco Tomas y Valiente 7, 28049 Cantoblanco, Madrid (Spain); Morales, M.P. [Instituto de Ciencia de Materiales de Madrid, CSIC, C/Sor Juana Ines de la Cruz 3, 28049 Cantoblanco, Madrid (Spain); Galindo, R. [Departamento de Quimica Fisica Aplicada, Facultad de Ciencias, Universidad Autonoma de Madrid, UAM, C/Francisco Tomas y Valiente 7, 28049 Cantoblanco, Madrid (Spain); Herrasti, P., E-mail: pilar.herrasti@uam.es [Departamento de Quimica Fisica Aplicada, Facultad de Ciencias, Universidad Autonoma de Madrid, UAM, C/Francisco Tomas y Valiente 7, 28049 Cantoblanco, Madrid (Spain); Menendez, N. [Departamento de Quimica Fisica Aplicada, Facultad de Ciencias, Universidad Autonoma de Madrid, UAM, C/Francisco Tomas y Valiente 7, 28049 Cantoblanco, Madrid (Spain)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Cobalt ferrite nanoparticles were synthesized by new electrochemical method. Black-Right-Pointing-Pointer Temperature affects to percentage of inclusion of Co and diameter of the synthesized nanoparticles. Black-Right-Pointing-Pointer At 80 Degree-Sign C and current densities of 50/25 mA cm{sup -2} applied to Fe and Co, respectively, a stoichiometric CoFe{sub 2}O{sub 4} nanoparticles with 40 nm of diameter were obtained. - Abstract: A new electrochemical method to synthesize cobalt ferrite nanoparticles has been developed. Magnetic measurement, Moessbauer spectroscopy, X-ray diffraction, inductive coupled plasma spectroscopy, and transmission electron microscopy were carried out to characterize the cobalt ferrites synthesized at different temperatures between 25 Degree-Sign C and 80 Degree-Sign C. These techniques confirm the efficiency of the electrochemical method. At room temperature a mixture of different compounds was obtained with a particle diameter around 20 nm, while at 80 Degree-Sign C the synthesis of cobalt ferrite leads to a stoichiometric spinel, with a crystallite size of 40 nm measured by Scherrer equation. The temperature was defined as an important parameter to obtain stoichiometric ferrites and different diameters.

  3. A MEMS-Based Flow Rate and Flow Direction Sensing Platform with Integrated Temperature Compensation Scheme

    Directory of Open Access Journals (Sweden)

    Chia-Yen Lee

    2009-07-01

    Full Text Available This study develops a MEMS-based low-cost sensing platform for sensing gas flow rate and flow direction comprising four silicon nitride cantilever beams arranged in a cross-form configuration, a circular hot-wire flow meter suspended on a silicon nitride membrane, and an integrated resistive temperature detector (RTD. In the proposed device, the flow rate is inversely derived from the change in the resistance signal of the flow meter when exposed to the sensed air stream. To compensate for the effects of the ambient temperature on the accuracy of the flow rate measurements, the output signal from the flow meter is compensated using the resistance signal generated by the RTD. As air travels over the surface of the cross-form cantilever structure, the upstream cantilevers are deflected in the downward direction, while the downstream cantilevers are deflected in the upward direction. The deflection of the cantilever beams causes a corresponding change in the resistive signals of the piezoresistors patterned on their upper surfaces. The amount by which each beam deflects depends on both the flow rate and the orientation of the beam relative to the direction of the gas flow. Thus, following an appropriate compensation by the temperature-corrected flow rate, the gas flow direction can be determined through a suitable manipulation of the output signals of the four piezoresistors. The experimental results have confirmed that the resulting variation in the output signals of the integrated sensors can be used to determine not only the ambient temperature and the velocity of the air flow, but also its direction relative to the sensor with an accuracy of ± 7.5o error.

  4. Effect of water electrolysis temperature of hydrogen production system using direct coupling photovoltaic and water electrolyzer

    Directory of Open Access Journals (Sweden)

    Tetsuhiko Maeda

    2016-01-01

    Full Text Available We propose control methods of a photovoltaic (PV-water electrolyzer (ELY system that generates hydrogen by controlling the number of ELY cells. The advantage of this direct coupling between PV and ELY is that the power loss of DC/DC converter is avoided. In this study, a total of 15 ELY cells are used. In the previous researches, the electrolyzer temperature was constantly controlled with a thermostat. Actually, the electrolyzer temperature is decided by the balance of the electrolysis loss and the heat loss to the outside. Here, the method to control the number of ELY cells was investigated. Maximum Power Point Tracking efficiency of more than 96% was achieved without ELY temperature control. Furthermore we construct a numerical model taking into account of ELY temperature. Using this model, we performed a numerical simulation of 1-year. Experimental data and the simulation results shows the validity of the proposed control method.

  5. RNAthermsw: direct temperature simulations for predicting the location of RNA thermometers.

    Directory of Open Access Journals (Sweden)

    Alexander Churkin

    Full Text Available The mechanism of RNA thermometers is a subject of growing interest. Also known as RNA thermosensors, these temperature-sensitive segments of the mRNA regulate gene expression by changing their secondary structure in response to temperature fluctuations. The detection of RNA thermometers in various genes of interest is valuable as it could lead to the discovery of new thermometers participating in fundamental processes such as preferential translation during heat-shock. RNAthermsw is a user-friendly webserver for predicting the location of RNA thermometers using direct temperature simulations. It operates by analyzing dotted figures generated as a result of a moving window that performs successive energy minimization folding predictions. Inputs include the RNA sequence, window size, and desired temperature change. RNAthermsw can be freely accessed at http://www.cs.bgu.ac.il/~rnathemsw/RNAthemsw/ (with the slash sign at the end. The website contains a help page with explanations regarding the exact usage.

  6. Colloidal Synthesis of Te-Doped Bi Nanoparticles: Low-Temperature Charge Transport and Thermoelectric Properties.

    Science.gov (United States)

    Gu, Da Hwi; Jo, Seungki; Jeong, Hyewon; Ban, Hyeong Woo; Park, Sung Hoon; Heo, Seung Hwae; Kim, Fredrick; Jang, Jeong In; Lee, Ji Eun; Son, Jae Sung

    2017-06-07

    Electronically doped nanoparticles formed by incorporation of impurities have been of great interest because of their controllable electrical properties. However, the development of a strategy for n-type or p-type doping on sub-10 nm-sized nanoparticles under the quantum confinement regime is very challenging using conventional processes, owing to the difficulty in synthesis. Herein, we report the colloidal chemical synthesis of sub-10 nm-sized tellurium (Te)-doped Bismuth (Bi) nanoparticles with precisely controlled Te content from 0 to 5% and systematically investigate their low-temperature charge transport and thermoelectric properties. Microstructural characterization of nanoparticles demonstrates that Te ions are successfully incorporated into Bi nanoparticles rather than remaining on the nanoparticle surfaces. Low-temperature Hall measurement results of the hot-pressed Te-doped Bi-nanostructured materials, with grain sizes ranging from 30 to 60 nm, show that the charge transport properties are governed by the doping content and the related impurity and nanoscale grain boundary scatterings. Furthermore, the low-temperature thermoelectric properties reveal that the electrical conductivity and Seebeck coefficient expectedly change with the Te content, whereas the thermal conductivity is significantly reduced by Te doping because of phonon scattering at the sites arising from impurities and nanoscale grain boundaries. Accordingly, the 1% Te-doped Bi sample exhibits a higher figure-of-merit ZT by ∼10% than that of the undoped sample. The synthetic strategy demonstrated in this study offers the possibility of electronic doping of various quantum-confined nanoparticles for diverse applications.

  7. Controlled synthesis of Pt/CS/PW{sub 12}-GNs composite as an anodic electrocatalyst for direct methanol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhongshui; Lei, Fengling; Ye, Lingting; Zhang, Xiaofeng; Lin, Shen, E-mail: shenlin@fjnu.edu.cn [Fujian Normal University, College of Chemistry & Chemical Engineering (China)

    2015-04-15

    Controlled assembly in aqueous solution was used to synthesize the well-organized Pt/CS/PW{sub 12}-GNs composite. By the aid of linear cationic polysaccharide chitosan, 2-D distribution worm-like Pt nanoparticles with their length and width of 15–20 and 3–4 nm, respectively, were formed on the surface of CS/PW{sub 12}-GNs using HCOOH as a reducing agent at room temperature. The introduction of CS leads to well dispersion of worm-like Pt nanoparticles, the electroactivity of H{sub 3}PW{sub 12}O{sub 40} (PW{sub 12}) alleviates CO poisoning toward Pt particles, and graphene nanosheets (GNs) ensure excellent electrical conductivity of the composites. The combined action among different components results in significantly enhanced catalytic activity of Pt/CS/PW{sub 12}-GNs toward methanol oxidation and better tolerance of CO. The as-synthesized Pt/CS/PW{sub 12}-GNs exhibit the forward peak current density of 445 mA mg{sup −1}, which is much higher than that (220 mA mg{sup −1}) for Pt/C-JM (the commercially available Johnson Matthey Hispec4000 catalyst, simplified as Pt/C-JM) and some recently reported Pt/graphene-based nanomaterials. The construction of 2-D distribution worm-like Pt nanoparticles and facile wet chemical synthesis strategy provide a promising way to develop superior performance electrocatalysts for direct methanol fuel cells applications.

  8. Optimized temperature control system integrated into a micro direct methanol fuel cell for extreme environments

    Science.gov (United States)

    Zhang, Qian; Wang, Xiaohong; Zhu, Yiming; Zhou, Yan'an; Qiu, Xinping; Liu, Litian

    This paper reports a micro direct methanol fuel cell (μDMFC) integrated with a heater and a temperature sensor to realize temperature control. A thermal model for the μDMFC is set up based on heat transfer and emission mechanisms. Several patterns of the heater are designed and simulated to produce a more uniform temperature profile. The μDMFC with optimized temperature control system, which has better temperature distribution, is fabricated by using MEMS technologies, assembled with polydimethylsiloxane (PDMS) material and polymethylmethacrylate (PMMA) holders, and characterized in two methods, one with different currents applied and another with different methanol velocities. A μDMFC integrated with the heater of different pattern and another one with aluminum holders, are assembled and tested also to verify the heating effect and temperature maintaining of packaging material. This work would make it possible for a μDMFC to enhance the performance by adjusting to an optimal temperature and employ in extreme environments, such as severe winter, polar region, outer space, desert and deep sea area.

  9. Timing matters: the underappreciated role of temperature ramp rate for shape control and reproducibility of quantum dot synthesis

    KAUST Repository

    Baumgardner, William J.

    2012-01-01

    Understanding the coupled kinetic and thermodynamics factors governing colloidal nanocrystals nucleation and growth are critical factors in the predictable and reproducible synthesis of advanced nanomaterials. We show that the temporal temperature profile is decisive in tuning the particle shape from pseudo-spherical to monodisperse cubes. The shape of the nanocrystals was characterized by transmission electron microscopy and X-ray diffraction. We introduce a mechanism for the shape controlled synthesis in the context of temperature-dependent nucleation and growth and provide experimental evidence to support it. © 2013 The Royal Society of Chemistry.

  10. Hydroxide Self-Feeding High-Temperature Alkaline Direct Formate Fuel Cells.

    Science.gov (United States)

    Li, Yinshi; Sun, Xianda; Feng, Ying

    2017-05-22

    Conventionally, both the thermal degradation of the anion-exchange membrane and the requirement of additional hydroxide for fuel oxidation reaction hinder the development of the high-temperature alkaline direct liquid fuel cells. The present work addresses these two issues by reporting a polybenzimidazole-membrane-based direct formate fuel cell (DFFC). Theoretically, the cell voltage of the high-temperature alkaline DFFC can be as high as 1.45 V at 90 °C. It has been demonstrated that a proof-of-concept alkaline DFFC without adding additional hydroxide yields a peak power density of 20.9 mW cm -2 , an order of magnitude higher than both alkaline direct ethanol fuel cells and alkaline direct methanol fuel cells, mainly because the hydrolysis of formate provides enough OH - ions for formate oxidation reaction. It was also found that this hydroxide self-feeding high-temperature alkaline DFFC shows a stable 100 min constant-current discharge at 90 °C, proving the conceptual feasibility. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Nanofluid Types, Their Synthesis, Properties and Incorporation in Direct Solar Thermal Collectors: A Review

    Science.gov (United States)

    Chamsa-ard, Wisut; Brundavanam, Sridevi; Fung, Chun Che; Fawcett, Derek; Poinern, Gerrard

    2017-01-01

    The global demand for energy is increasing and the detrimental consequences of rising greenhouse gas emissions, global warming and environmental degradation present major challenges. Solar energy offers a clean and viable renewable energy source with the potential to alleviate the detrimental consequences normally associated with fossil fuel-based energy generation. However, there are two inherent problems associated with conventional solar thermal energy conversion systems. The first involves low thermal conductivity values of heat transfer fluids, and the second involves the poor optical properties of many absorbers and their coating. Hence, there is an imperative need to improve both thermal and optical properties of current solar conversion systems. Direct solar thermal absorption collectors incorporating a nanofluid offers the opportunity to achieve significant improvements in both optical and thermal performance. Since nanofluids offer much greater heat absorbing and heat transfer properties compared to traditional working fluids. The review summarizes current research in this innovative field. It discusses direct solar absorber collectors and methods for improving their performance. This is followed by a discussion of the various types of nanofluids available and the synthesis techniques used to manufacture them. In closing, a brief discussion of nanofluid property modelling is also presented. PMID:28561802

  12. Nanofluid Types, Their Synthesis, Properties and Incorporation in Direct Solar Thermal Collectors: A Review.

    Science.gov (United States)

    Chamsa-Ard, Wisut; Brundavanam, Sridevi; Fung, Chun Che; Fawcett, Derek; Poinern, Gerrard

    2017-05-31

    The global demand for energy is increasing and the detrimental consequences of rising greenhouse gas emissions, global warming and environmental degradation present major challenges. Solar energy offers a clean and viable renewable energy source with the potential to alleviate the detrimental consequences normally associated with fossil fuel-based energy generation. However, there are two inherent problems associated with conventional solar thermal energy conversion systems. The first involves low thermal conductivity values of heat transfer fluids, and the second involves the poor optical properties of many absorbers and their coating. Hence, there is an imperative need to improve both thermal and optical properties of current solar conversion systems. Direct solar thermal absorption collectors incorporating a nanofluid offers the opportunity to achieve significant improvements in both optical and thermal performance. Since nanofluids offer much greater heat absorbing and heat transfer properties compared to traditional working fluids. The review summarizes current research in this innovative field. It discusses direct solar absorber collectors and methods for improving their performance. This is followed by a discussion of the various types of nanofluids available and the synthesis techniques used to manufacture them. In closing, a brief discussion of nanofluid property modelling is also presented.

  13. Nanofluid Types, Their Synthesis, Properties and Incorporation in Direct Solar Thermal Collectors: A Review

    Directory of Open Access Journals (Sweden)

    Wisut Chamsa-ard

    2017-05-01

    Full Text Available The global demand for energy is increasing and the detrimental consequences of rising greenhouse gas emissions, global warming and environmental degradation present major challenges. Solar energy offers a clean and viable renewable energy source with the potential to alleviate the detrimental consequences normally associated with fossil fuel-based energy generation. However, there are two inherent problems associated with conventional solar thermal energy conversion systems. The first involves low thermal conductivity values of heat transfer fluids, and the second involves the poor optical properties of many absorbers and their coating. Hence, there is an imperative need to improve both thermal and optical properties of current solar conversion systems. Direct solar thermal absorption collectors incorporating a nanofluid offers the opportunity to achieve significant improvements in both optical and thermal performance. Since nanofluids offer much greater heat absorbing and heat transfer properties compared to traditional working fluids. The review summarizes current research in this innovative field. It discusses direct solar absorber collectors and methods for improving their performance. This is followed by a discussion of the various types of nanofluids available and the synthesis techniques used to manufacture them. In closing, a brief discussion of nanofluid property modelling is also presented.

  14. Template-directed synthesis of linear porphyrin oligomers: classical, Vernier and mutual Vernier.

    Science.gov (United States)

    Kamonsutthipaijit, Nuntaporn; Anderson, Harry L

    2017-04-01

    Three different types of template-directed syntheses of linear porphyrin oligomers are presented. In the classical approach the product has the same number of binding sites as the template, whereas in Vernier reactions the product has the lowest common multiple of the numbers of binding sites in the template and the building block. Mutual Vernier templating is like Vernier templating except that both strands of the Vernier complex undergo coupling simultaneously, so that it becomes impossible to say which is the 'template' and which is the 'building block'. The template-directed synthesis of monodisperse linear oligomers is more difficult than that of cyclic oligomers, because the products of linear templating have reactive ends. All three types of templating are demonstrated here, and used to prepare a nickel(ii) porphyrin dodecamer with 4-pyridyl substituents on all twelve porphyrin units. The stabilities and cooperativities of the double-strand complexes involved in these reactions were investigated by UV-vis-NIR titration. The four-rung ladder duplex has a stability constant of about 2 × 1018 M-1 in dichloromethane at 298 K.

  15. Applying Tiab’s direct synthesis technique to dilatant non-Newtonian/Newtonian fluids

    Directory of Open Access Journals (Sweden)

    Javier Andrés Martínez

    2011-08-01

    Full Text Available Non-Newtonian fluids, such as polymer solutions, have been used by the oil industry for many years as fracturing agents and drilling mud. These solutions, which normally include thickened water and jelled fluids, are injected into the formation to enhanced oil recovery by improving sweep efficiency. It is worth noting that some heavy oils behave non-Newtonianly. Non-Newtonian fluids do not have direct proportionality between applied shear stress and shear rate and viscosity varies with shear rate depending on whether the fluid is either pseudoplastic or dilatant. Viscosity decreases as shear rate increases for the former whilst the reverse takes place for dilatants. Mathematical models of conventional fluids thus fail when applied to non-Newtonian fluids. The pressure derivative curve is introduced in this descriptive work for a dilatant fluid and its pattern was observed. Tiab’s direct synthesis (TDS methodology was used as a tool for interpreting pressure transient data to estimate effective permeability, skin factors and non-Newtonian bank radius. The methodology was successfully verified by its application to synthetic examples. Also, comparing it to pseudoplastic behavior, it was found that the radial flow regime in the Newtonian zone of dilatant fluids took longer to form regarding both the flow behavior index and consistency factor.

  16. Combustion synthesized TiO{sub 2} for enhanced photocatalytic activity under the direct sunlight-optimization of titanylnitrate synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Daya Mani, A. [Department of Chemistry, IIT Hyderabad, Yeddumailaram 502 205 (India); Laporte, V. [Ecole Polytechnique Federale de Lausanne (EPFL), Interdisciplinary Centre for Electron Microscopy – Surface Analysis Facility, CH-Lausanne (Switzerland); Ghosal, P. [Defence Metallurgical Research Laboratory (DMRL), Kanchanbagh, Hyderabad 500 058 (India); Subrahmanyam, Ch., E-mail: csubbu@iith.ac.in [Department of Chemistry, IIT Hyderabad, Yeddumailaram 502 205 (India)

    2012-09-15

    Graphical abstract: Effect of oxidant on the combustion synthesis of TiO{sub 2} has been studied by preparing titanylnitrate in four different ways from Ti(IV) iso-propoxide. It is observed that oxidant preparation method has a significant effect on physico-chemical as well as photocatalytic properties of TiO{sub 2}. All the catalysts showed excellent photocatalytic activity than Degussa P-25 under direct sunlight for the degradation of a textile dye (methylene blue), without the need of external light sources, oxygen supply and reactor systems. Highlights: ► Optimized synthesis of titanylnitrate. ► Influence of titanylnitrate synthesis on the physico-chemical properties of TiO{sub 2} prepared by combustion synthesis. ► Development of highly efficient TiO{sub 2} photocatalysts those are active under the direct sunlight in open atmosphere. ► Degradation of the textile dye (methylene blue) under direct sunlight. -- Abstract: Optimized synthesis of Ti-precursor ‘titanylnitrate’ for one step combustion synthesis of N- and C-doped TiO{sub 2} catalysts were reported and characterized by using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), diffused reflectance UV–vis spectroscopy, N{sub 2} adsorption and X-ray photoelectron spectroscopy (XPS). XRD confirmed the formation of TiO{sub 2} anatase and nano-crystallite size which was further confirmed by TEM. UV-DRS confirmed the decrease in the band gap to less than 3.0 eV, which was assigned due to the presence of C and N in the framework of TiO{sub 2} as confirmed by X-ray photoelectron spectroscopy. Degradation of methylene blue in aqueous solution under the direct sunlight was carried out and typical results indicated the better performance of the synthesized catalysts than Degussa P-25.

  17. Synthesis of high saturation magnetic iron oxide nanomaterials via low temperature hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Bhavani, P.; Rajababu, C.H. [Department of Materials Science & Nanotechnology, Yogivemana University, Vemanapuram 516003, Kadapa (India); Arif, M.D. [Environmental Magnetism Laboratory, Indian Institute of Geomagnetism (IIG), Navi Mumbai 410218, Mumbai (India); Reddy, I. Venkata Subba [Department of Physics, Gitam University, Hyderabad Campus, Rudraram, Medak 502329 (India); Reddy, N. Ramamanohar, E-mail: manoharphd@gmail.com [Department of Materials Science & Nanotechnology, Yogivemana University, Vemanapuram 516003, Kadapa (India)

    2017-03-15

    Iron oxide nanoparticles (IONPs) were synthesized through a simple low temperature hydrothermal approach to obtain with high saturation magnetization properties. Two series of iron precursors (sulfates and chlorides) were used in synthesis process by varying the reaction temperature at a constant pH. The X-ray diffraction pattern indicates the inverse spinel structure of the synthesized IONPs. The Field emission scanning electron microscopy and high resolution transmission electron microscopy studies revealed that the particles prepared using iron sulfate were consisting a mixer of spherical (16–40 nm) and rod (diameter ~20–25 nm, length <100 nm) morphologies that synthesized at 130 °C, while the IONPs synthesized by iron chlorides are found to be well distributed spherical shapes with size range 5–20 nm. On other hand, the IONPs synthesized at reaction temperature of 190 °C has spherical (16–46 nm) morphology in both series. The band gap values of IONPs were calculated from the obtained optical absorption spectra of the samples. The IONPs synthesized using iron sulfate at temperature of 130 °C exhibited high saturation magnetization (M{sub S}) of 103.017 emu/g and low remanant magnetization (M{sub r}) of 0.22 emu/g with coercivity (H{sub c}) of 70.9 Oe{sub ,} which may be attributed to the smaller magnetic domains (d{sub m}) and dead magnetic layer thickness (t). - Highlights: • Comparison of iron oxide materials prepared with Fe{sup +2}/Fe{sup +3} sulfates and chlorides at different temperatures. • We prepared super-paramagnetic and soft ferromagnetic magnetite nanoparticles. • We report higher saturation magnetization with lower coercivity.

  18. Low temperature synthesis and field emission characteristics of single to few layered graphene grown using PECVD

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Avshish; Khan, Sunny; Zulfequar, M.; Harsh; Husain, Mushahid, E-mail: mush_reslab@rediffmail.com

    2017-04-30

    Highlights: • Graphene was synthesized by PECVD system at a low temperature of 600 °C. • From different characterization techniques, the presence of single and few layered graphene was confirmed. • X-ray diffraction pattern of the graphene showed single crystalline nature of the film. • The as-grown graphene films were observed extremely good field emitters with long term emission current stability. - Abstract: In this work, high-quality graphene has successfully been synthesized on copper (Cu) coated Silicon (Si) substrate at very large-area by plasma enhanced chemical vapor deposition system. This method is low cost and highly effective for synthesizing graphene relatively at low temperature of 600 °C. Electron microscopy images have shown that surface morphology of the grown samples is quite uniform consisting of single layered graphene (SLG) to few layered graphene (FLG). Raman spectra reveal that graphene has been grown with high-quality having negligible defects and the observation of G and G' peaks is also an indicative of stokes phonon energy shift caused due to laser excitation. Scanning probe microscopy image also depicts the synthesis of single to few layered graphene. The field emission characteristics of as-grown graphene samples were studied in a planar diode configuration at room temperature. The graphene samples were observed to be a good field emitter having low turn-on field, higher field amplification factor and long term emission current stability.

  19. Silver nanoparticles: Influence of the temperature synthesis on the particles’ morphology

    Science.gov (United States)

    Piñero, S.; Camero, S.; Blanco, S.

    2017-01-01

    Silver nanoparticles have a wide range of applications in the medical field, textile and food industries. These and other applications can be found due to the relation between its size and morphology. In this study the influence of bath temperature on the morphology and size of silver nanoparticles are evaluated, which are obtained by chemical reduction of AgNO3 using three reducing agents: sodium borohydride, ascorbic acid and sodium citrate. The evaluation carried out by the traditional UV-vis Spectrophotometric analysis and with High Resolution Transmission Electron Microscopy. The UV-vis spectrum of the silver colloids obtained by chemical reduction using three different reducing agents shows the effect of the temperature change on the growing and aggregative process. The final effect on the morphology, size and aggregation of the particles was confirmed by TEM. The result suggests a change in the growing mechanism, conducted by aggregation of atoms at 5 and 20°C degrees and aggregation of clusters at higher temperatures. Moreover in this work the main synthesis methods of nanomaterials are described.

  20. Low Temperature Solid-State Synthesis and Characterization of LaBO3

    Directory of Open Access Journals (Sweden)

    Azmi Seyhun KIPÇAK

    2016-11-01

    Full Text Available Rare earth (lanthanide series borates, possess high vacuum ultraviolet (VUV transparency, large electronic band gaps, chemical and environmental stability and exceptionally large optical damage thresholds and used in the development of plasma display panels (PDPs. In this study the synthesis of lanthanum borates via solid-state method is studied. For this purpose, lanthanum oxide (La2O3 and boric acid (H3BO3 are used for as lanthanum and boron sources, respectively. Different elemental molar ratios of La to B (between 3:1 to 1:6 as La2O3:H3BO3 were reacted by solid-state method at the reaction temperatures between 500°C - 700°C with the constant reaction time of 4 h. Following the synthesis, characterizations of the synthesized products are conducted by X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FT-IR, Raman spectroscopy and scanning electron microscope (SEM. From the results of the experiments, three types of lanthanum borates of; La3BO6, LaBO3 and La(BO23 were observed at different reaction parameters. Among these three types of lanthanum borates LaBO3 phase were obtained as a major phase.

  1. Carbon Isotope Systematics in Mineral-Catalyzed Hydrothermal Organic Synthesis Processes at High Temperature and Pressures

    Science.gov (United States)

    Fu, Qi; Socki, R. A.; Niles, Paul B.

    2011-01-01

    Observation of methane in the Martian atmosphere has been reported by different detection techniques. Reduction of CO2 and/or CO during serpentization by mineral surface catalyzed Fischer-Tropsch Type (FTT) synthesis may be one possible process responsible for methane generation on Mars. With the evidence a recent study has discovered for serpentinization in deeply buried carbon rich sediments, and more showing extensive water-rock interaction in Martian history, it seems likely that abiotic methane generation via serpentinization reactions may have been common on Mars. Experiments involving mineral-catalyzed hydrothermal organic synthesis processes were conducted at 750 C and 5.5 Kbars. Alkanes, alcohols and carboxylic acids were identified as organic compounds. No "isotopic reversal" of delta C-13 values was observed for alkanes or carboxylic acids, suggesting a different reaction pathway than polymerization. Alcohols were proposed as intermediaries formed on mineral surfaces at experimental conditions. Carbon isotope data were used in this study to unravel the reaction pathways of abiotic formation of organic compounds in hydrothermal systems at high temperatures and pressures. They are instrumental in constraining the origin and evolution history of organic compounds on Mars and other planets.

  2. Cuprous Oxide Scale up: Gram Production via Bulk Synthesis using Classic Solvents at Low Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Hall, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Han, T. Y. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-05-07

    Cuprous oxide is a p-type semiconducting material that has been highly researched for its interesting properties. Many small-scale syntheses have exhibited excellent control over size and morphology. As the demand for cuprous oxide grows, the synthesis method need to evolve to facilitate large-scale production. This paper supplies a facile bulk synthesis method for Cu₂O on average, 1-liter reaction volume can produce 1 gram of particles. In order to study the shape and size control mechanisms on such a scale, the reaction volume was diminished to 250 mL producing on average 0.3 grams of nanoparticles per batch. Well-shaped nanoparticles have been synthesized using an aqueous solution of CuCl₂, NaOH, SDS surfactant, and NH₂OH-HCl at mild temperatures. The time allotted between the addition of NaOH and NH₂OH-HCl was determined to be critical for Cu(OH)2 production, an important precursor to the final produce The effects of stirring rates on a large scale was also analyzed during reagent addition and post reagent addition. A morphological change from rhombic dodecahedra to spheres occurred as the stirring speed was increased. The effects of NH₂OH-HCl concentration were also studied to control the etching effects of the final product.

  3. Low temperature synthesis and sintering behaviour of Gd-doped ceria nanosized powders: comparison between two synthesis procedures

    Directory of Open Access Journals (Sweden)

    Tartaj, J.

    2009-04-01

    Full Text Available Two different routes of synthesis of Ce0.9Gd0.1O1.95 (CGO nanopowders are presented; the ethylene glycol-metal nitrate polymerized complex solution method and the precipitation technique using ammonia as the precipitant agent. The powders characteristics were examined by X-ray diffraction (XRD, transmission electron microscopy (TEM, Brunauer-Emmett-Teller (BET surface area and simultaneous thermogravimetric and differential thermal analysis (TG/DTA. Scanning electron microscopy (SEM observations were used to determine the agglomeration degree of the powders, and the uniformity of the green compacts. The Hg-porosimetry results were used to investigate the pore size. The densification process was studied by constant heating rate dilatometry and isothermal sintering at different temperatures. Microstructural development of each sample at different sintering temperatures and times was followed by SEM.

    Se presentan dos diferentes rutas de síntesis de nanopolvos de Ce0.9Gd0.1O1.95 (CGO: precipitación de hidróxidos, a partir de soluciones de nitratos utilizando amonia como agente precipitante y formación de complejos polimerizados etilene-glicol nitratos metálicos. Las características de los polvos se determinaron por DRX, microscopía de transmisión (TEM, superficie específica por Brunauer-Emmett-Teller (BET, y ensayos de ATD/ATG. El grado de aglomeración de los nanopolvos y la uniformidad de los compactos en verde se ha observado por Microscopía electrónica de barrido, (SEM. El tamaño de poro de los compactos en verde se ha medido mediante porosimetría de Hg. El comportamiento a la sinterización se ha evaluado por dilatometría a velocidad de calentamiento constante y por sinterización isoterma a diferentes temperaturas. La evolución microestructural se ha seguido por SEM.

  4. Mesoporous Structure Control of Silica in Room-Temperature Synthesis under Basic Conditions

    Directory of Open Access Journals (Sweden)

    Jeong Wook Seo

    2015-01-01

    Full Text Available Various types of mesoporous silica, such as continuous cubic-phase MCM-48, hexagonal-phase MCM-41, and layer-phase spherical silica particles, have been synthesized at room temperature using cetyltrimethylammonium bromide as a surfactant, ethanol as a cosurfactant, tetraethyl orthosilicate as a silica precursor, and ammonia as a condensation agent. Special care must be taken both in the filtering of the resultant solid products and in the drying process. In the drying process, further condensation of the silica after filtering was induced. As the surfactant and cosurfactant concentrations in the reaction mixture increased and the NH3 concentration decreased, under given conditions, continuous cubic MCM-48 and layered silica became the dominant phases. A cooperative synthesis mechanism, in which both the surfactant and silica were involved in the formation of mesoporous structures, provided a good explanation of the experimental results.

  5. Synthesis of Trimethylolpropane Esters of Calophyllum Methyl Esters : Effect of Temperature and Molar Ratio

    Directory of Open Access Journals (Sweden)

    Yeti Widyawati

    2014-12-01

    Full Text Available Trimethylolpropane esters were synthesized by transesterification of calophyllum methyl esters and trimethylolpropane using a calcium oxide as the catalyst. The results showed that the optimal reaction conditions (temperature: 130 0C, reaction time: 5 h, reactant molar ratio: 3.9:1, catalyst amount 3%w/w, and formed  trimethylolpropane ester of 79.0% were obtained. The basic physicochemical properties of the trimethylolpropane esters were the following : kinematic viscosities of 56.40 cSt and 8.8 cSt at 40 0C and 100 0C,  viscosity index 193, flash point 218 0C and pour point -3 0C. So Methyl esters of fatty acids of would callophylum  methyl ester is good raw material for the synthesis of lubricating oils.

  6. A liquid metal reaction environment for the room-temperature synthesis of atomically thin metal oxides

    Science.gov (United States)

    Zavabeti, Ali; Ou, Jian Zhen; Carey, Benjamin J.; Syed, Nitu; Orrell-Trigg, Rebecca; Mayes, Edwin L. H.; Xu, Chenglong; Kavehei, Omid; O’Mullane, Anthony P.; Kaner, Richard B.; Kalantar-zadeh, Kourosh; Daeneke, Torben

    2017-10-01

    Two-dimensional (2D) oxides have a wide variety of applications in electronics and other technologies. However, many oxides are not easy to synthesize as 2D materials through conventional methods. We used nontoxic eutectic gallium-based alloys as a reaction solvent and co-alloyed desired metals into the melt. On the basis of thermodynamic considerations, we predicted the composition of the self-limiting interfacial oxide. We isolated the surface oxide as a 2D layer, either on substrates or in suspension. This enabled us to produce extremely thin subnanometer layers of HfO2, Al2O3, and Gd2O3. The liquid metal–based reaction route can be used to create 2D materials that were previously inaccessible with preexisting methods. The work introduces room-temperature liquid metals as a reaction environment for the synthesis of oxide nanomaterials with low dimensionality.

  7. Low-temperature synthesis of zeolite from perlite waste — Part II: characteristics of the products

    Science.gov (United States)

    Król, Magdalena; Morawska, Justyna; Mozgawa, Włodzimierz; Pichór, Waldemar

    2014-12-01

    The paper investigates the properties of sodium zeolites synthesized using the hydrothermal method under autogenous pressure at low temperature with NaOH solutions of varying concentrations. During this modification, zeolites X, Na-P1 and hydroxysodalite were synthesized. The synthesis parameters, and thus, phase composition of resulting samples, significantly affected the specific surface area (SSA) and cation exchange capacity (CEC). SSA increased from 2.9 m2/g to a maximum of 501.2 m2/g, while CEC rose from 16 meq/100 g to a maximum of 500 meq/100 g. The best properties for use as a sorbent were obtained for perlite waste modified with 4.0 M NaOH at 70 °C or 80 °C.

  8. Rapid, room-temperature synthesis of amorphous selenium/protein composites using Capsicum annuum L extract

    Science.gov (United States)

    Li, Shikuo; Shen, Yuhua; Xie, Anjian; Yu, Xuerong; Zhang, Xiuzhen; Yang, Liangbao; Li, Chuanhao

    2007-10-01

    We describe the formation of amorphous selenium (α-Se)/protein composites using Capsicum annuum L extract to reduce selenium ions (SeO32-) at room temperature. The reaction occurs rapidly and the process is simple and easy to handle. A protein with a molecular weight of 30 kDa extracted from Capsicum annuum L not only reduces the SeO32- ions to Se0, but also controls the nucleation and growth of Se0, and even participates in the formation of α-Se/protein composites. The size and shell thickness of the α-Se/protein composites increases with high Capsicum annuum L extract concentration, and decreases with low reaction solution pH. The results suggest that this eco-friendly, biogenic synthesis strategy could be widely used for preparing inorganic/organic biocomposites. In addition, we also discuss the possible mechanism of the reduction of SeO32- ions by Capsicum annuum L extract.

  9. Catalytic CVD Synthesis of Carbon Nanotubes: Towards High Yield and Low Temperature Growth

    Science.gov (United States)

    Magrez, Arnaud; Seo, Jin Won; Smajda, Rita; Mionić, Marijana; Forró, László

    2010-01-01

    The catalytic chemical vapor deposition (CCVD) is currently the most flexible and economically attractive method for the growth of carbon nanotubes. Although its principle is simple, the precisely controlled growth of carbon nanotubes remains very complex because many different parameters influence the growth process. In this article, we review our recent results obtained on the synthesis of carbon nanotubes via CCVD. We discuss the role of the catalyst and the catalyst support. Our recent results obtained from the water assisted growth and the equimolar C2H2-CO2 reaction are also discussed. Both procedures lead to significantly enhanced carbon nanotube growth. In particular, the latter allows growing carbon nanotubes on diverse substrate materials at low temperatures. PMID:28883358

  10. The formation of pentagonal Ni nanowires: dependence on the stretching direction and the temperature

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Mochales, P. [Departamento de Fisica de la Materia Condensada, Facultad de Ciencias, Universidad Autonoma de Madrid, c/Francisco Tomas y Valiente 7, Cantoblanco, 28049 Madrid (Spain); Paredes, R. [Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas, Apto. 20632, Caracas 1020A (Venezuela); Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, c/Sor Juana Ines de la Cruz 3, Cantoblanco, 28049 Madrid (Spain); Pelaez, S.; Serena, P.A. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, c/Sor Juana Ines de la Cruz 3, Cantoblanco, 28049 Madrid (Spain)

    2008-06-15

    We have constructed computational minimum cross-section histograms that statistically unveil the presence of preferred configuration during the breakage of Ni nanowires. The computed histograms showed strong dependence on the nanowire stretching direction. For the[100] and[110] stretching directions we have observed a very large peak associated to a minimum cross-section of 5 atoms. We have confirmed that the configurations that contribute to this peak are staggered pentagonal nanowires. We have found that the formation of these nanowires is enhanced by increasing the temperature up to 550 K. At higher temperatures, the formation of pentagonal nanowires declines due to the competence against the nanowire melting processes. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Strain rate and temperature effects on crack initiation of direct aged 718 Alloy

    OpenAIRE

    Perrais Maxime; Burteau Anthony; Seror Alexandre; Poquillon Dominique; Andrieu Eric

    2014-01-01

    During mechanical tests at high temperature in an oxidizing atmosphere, the effects of strain rate on crack initiation are noticeable. This effect is due to a coupling between local mechanical loading and oxidation. Samples were machined in a turbine disk made of direct aged alloy 718. Tests were performed to understand the effect of these couplings on crack initiation and to ensure lifetime is optimized. This study compared the cracking resistance of two different specimen geometries at a gi...

  12. Temperature tuning from direct to inverted bistable electroluminescence in resonant tunneling diodes

    Science.gov (United States)

    Hartmann, F.; Pfenning, A.; Rebello Sousa Dias, M.; Langer, F.; Höfling, S.; Kamp, M.; Worschech, L.; Castelano, L. K.; Marques, G. E.; Lopez-Richard, V.

    2017-10-01

    We study the electroluminescence (EL) emission of purely n-doped resonant tunneling diodes in a wide temperature range. The paper demonstrates that the EL originates from impact ionization and radiative recombination in the extended collector region of the tunneling device. Bistable current-voltage response and EL are detected and their respective high and low states are tuned under varying temperature. The bistability of the EL intensity can be switched from direct to inverted with respect to the tunneling current and the optical on/off ratio can be enhanced with increasing temperature. One order of magnitude amplification of the optical on/off ratio can be attained compared to the electrical one. Our observation can be explained by an interplay of moderate peak-to-valley current ratios, large resonance voltages, and electron energy loss mechanisms, and thus, could be applied as an alternative route towards optoelectronic applications of tunneling devices.

  13. A Novel Approach in Cinnamic Acid Synthesis: Direct Synthesis of Cinnamic Acids from Aromatic Aldehydes and Aliphatic Carboxylic Acids in the Presence of Boron Tribromide

    Directory of Open Access Journals (Sweden)

    M. Onciu

    2005-02-01

    Full Text Available Cinnamic acids have been prepared in moderate to high yields by a new direct synthesis using aromatic aldehydes and aliphatic carboxylic acids, in the presence of boron tribromide as reagent, 4-dimethylaminopyridine (4-DMAP and pyridine (Py as bases and N-methyl-2-pyrolidinone (NMP as solvent, at reflux (180-190°C for 8-12 hours.

  14. Direct dimethyl ether fueling of a high temperature polymer fuel cell

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Vassiliev, Anton; Olsen, M.I.

    2012-01-01

    Direct dimethyl ether (DME) fuel cells suffer from poor DME–water miscibility and so far peak powers of only 20–40 mW cm−2 have been reported. Based on available literature on solubility of dimethyl ether (DME) in water at ambient pressure it was estimated that the maximum concentration of DME...... at 80 °C will be 300–600 times lower than the ratio 1 to 3 which is the stoichiometric ratio for full conversion to CO2. To overcome this dilution problem a high temperature polymer fuel cell was operated on DME–water vapor at ambient pressure and with air as oxidant. A peak power density of 67 mW cm−2...... was measured at 200 °C. A series of performance curves at temperatures ranging from 150 to 250 °C showed a pronounced temperature effect on the performance. Comparison was made between performances as direct DME and direct methanol cells and the difference was not as large as normally seen with conventional...

  15. Synthesis of large uniform gold and core-shell gold-silver nanoparticles: Effect of temperature control

    Science.gov (United States)

    Tiunov, I. A.; Gorbachevskyy, M. V.; Kopitsyn, D. S.; Kotelev, M. S.; Ivanov, E. V.; Vinokurov, V. A.; Novikov, A. A.

    2016-01-01

    The temperatures of nucleation and growth for gold and silver nanoparticles are quite close to each other in citrate-based seeded-growth synthesis. Hence, thorough temperature control during the synthesis of gold and gold-silver core-shell nanoparticles is expected to improve the yield of uniform non-aggregated nanoparticles suitable for selective contrasting of surface defects. Gold and gold-silver core-shell nanoparticles of size ranging from 20 to 160 nm were synthesized using various means of temperature control. The synthesized nanoparticles were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS) and UV-Vis spectroscopy. Model nanocracks were milled on pipeline steel specimen by focused ion beam (FIB). It was found that to produce large uniform core-shell nanoparticles, thorough temperature control is required during formation of the gold seeds and the silver shell. Moreover, the synthesized nanoparticles were used for selective contrasting of defects on metal surface.

  16. Fibers innovative burning and reuse by Self-propagating High temperature Synthesis (SHS)

    Science.gov (United States)

    Caratto, Valentina; Belfortini, Claudio; Musi, Luigi; Gaggero, Laura; Ferretti, Maurizio

    2016-04-01

    The treatment of asbestos containing waste deriving from civil building and industrial applications is a social alert and an environmental problem. The project LIFE12 ENV/IT 000295 FIBERS "Fibers innovative burning and reuse by Self-propagating High temperature Synthesis (SHS)" has developed an innovative technique alternative to conventional high T processes. The University of Genoa has developed an apparatus and a technique for triggering the breakdown reaction of chrysotile by means of an alumino-thermic reaction in a process of combustion synthesis well known as Self-propagating High temperature Synthesis or SHS. This approach yielded interesting results and allowed the development of an efficient method for inerting natural asbestos fibers and man-made products carrying fibers at the scale of some grams [1]. The experiments were based on the couples Fe2O3/Mg by implementation of two prototype plants. The varying parameters were: 1) different Asbestos-Containing Waste (ACW) massive (Eternit, linoleum) and friable asbestos; 2) ACW abundance; 3) size of the pellet 4) under two triggering systems (induction by a W coil and oxyacetylene torch). The reactions were carried in two configurations: a) discontinuous, allowed us to obtain data for the development and fine-tuning of the reaction, b) continuous, was indispensable for the development and fine-tuning of the process parameters towards industrial scale up. After the combustive reaction all samples were characterized by SEM-EDS and XRPD analysis. All experiments demonstrated effective in destructing the fibrous habit of chrysotile, turning its composition to stubby olivine grains. We optimized the parameters to achieve complete conversion of the asbestos to mineral grains in all the cases. The efficiency of the SHS reaction in the discontinuous and continuous configurations was highlighted by the characterization of the post-combustion material under SEM-EDS and XRPD that verified the absence of fibers within

  17. Phage-Directed Synthesis of Photoluminescent Zinc Oxide Nanoparticles under Benign Conditions.

    Science.gov (United States)

    Żelechowska, Kamila; Karczewska-Golec, Joanna; Karczewski, Jakub; Łoś, Marcin; Kłonkowski, Andrzej M; Węgrzyn, Grzegorz; Golec, Piotr

    2016-09-21

    Biological systems, especially bacteriophages and peptides, are an attractive green alternative to other known methods of nanoparticle synthesis. In this work, for the first time, bacteriophages were employed to synthesize a specific peptide, capable of producing nanoparticles (NPs). Derivatives of M13 bacteriophage exposing a ZnO-binding peptide (TMGANLGLKWPV) on either pIII or pVIII phage coat protein were constructed and used as a biotemplate. The exposition of the ZnO-binding peptide, synthesized by phages during their propagation in bacteria, on M13 virions provided a groundwork for growing ZnO nanostructures. Depending on the recombinant phage type used (M13-pIII-ZnO or M13-pVIII-ZnO), well separated ZnO NPs or complex 3D structures of ZnO NPs of ca. 20-40 nm were synthesized at room temperature. The synthesized ZnO nanoparticles served as a luminescent material that emitted light near the short wavelength end of the visible region (at ca. 400 nm). The next very low intensity emission band at 530 nm demonstrated that the ZnO material obtained is characterized by a low concentration of surface defects.

  18. Methylcellulose-Directed Synthesis of Nanocrystalline Zeolite NaA with High CO2 Uptake

    Directory of Open Access Journals (Sweden)

    Dilshod Shakarova

    2014-07-01

    Full Text Available Zeolite NaA nanocrystals with a narrow particle size distribution were prepared by template-free hydrothermal synthesis in thermo-reversible methylcellulose gels. The effects of the amount of methylcellulose, crystallization time and hydrothermal treatment temperature on the crystallinity and particle size distribution of the zeolite NaA nanocrystals were investigated. We found that the thermogelation of methylcellulose in the alkaline Na2O-SiO2-Al2O3-H2O system played an important role in controlling the particle size. The synthesized zeolite nanocrystals are highly crystalline, as demonstrated by X-ray diffraction (XRD, and scanning electron microscopy (SEM shows that the nanocrystals can also display a well-defined facetted morphology. Gas adsorption studies on the synthesized nanocrystalline zeolite NaA showed that nanocrystals with a size of 100 nm displayed a high CO2 uptake capacity (4.9 mmol/g at 293 K at 100 kPa and a relatively rapid uptake rate compared to commercially available, micron-sized particles. Low-cost nanosized zeolite adsorbents with a high and rapid uptake are important for large scale gas separation processes, e.g., carbon capture from flue gas.

  19. BF3.SiO2: an efficient catalyst for the synthesis of azo dyes at room temperature

    Directory of Open Access Journals (Sweden)

    Bi Bi Fatemeh Mirjalili

    2012-07-01

    Full Text Available A rapid one-pot method has been developed for the synthesis of azo dyes via ‎sequential diazotization–diazo coupling of aromatic amines with coupling agents at room ‎temperature in the presence of BF3.SiO2 as acidic catalyst. The obtained aryl diazonium salts bearing silica supported boron tri-flouride counter ion‎ was sufficiently stable to be kept at room ‎temperature in the dry state.‎

  20. Self-Propagating High-Temperature Synthesis of Titanium Carbosilicide and Electrically Conductive Composite Coatings on its Basis

    Science.gov (United States)

    Shulpekov, A. M.; Lepakova, O. K.; Golobokov, N. N.; Dyukarev, M. A.

    2017-09-01

    Titanium carbosilicide is obtained by the method of self-propagating high-temperature synthesis with titanium and ferrosilicon (with silicon content of 80 mass %) used as initial products. Addition of TiSi2 to the endproduct with the subsequent heat treatment allows the content of titanium silicide to be increased. The materials based on titanium carbosilicide provide electroconductivity of polymer composite coatings at temperatures exceeding 350°C.

  1. Development of High Efficiency and Low Emission Low Temperature Combustion Diesel Engine with Direct EGR Injection

    Science.gov (United States)

    Ho, R. J.; Kumaran, P.; Yusoff, M. Z.

    2016-03-01

    Focus on energy and environmental sustainability policy has put automotive research & development directed to developing high efficiency and low pollutant power train. Diffused flame controlled diesel combustion has reach its limitation and has driven R&D to explore other modes of combustions. Known effective mode of combustion to reduce emission are Low temperature combustion (LTC) and homogeneous charge combustion ignition by suppressing Nitrogen Oxide(NOx) and Particulate Matter (PM) formation. The key control to meet this requirement are chemical composition and distribution of fuel and gas during a combustion process. Most research to accomplish this goal is done by manipulating injected mass flow rate and varying indirect EGR through intake manifold. This research paper shows viable alternative direct combustion control via co-axial direct EGR injection with fuel injection process. A simulation study with OpenFOAM is conducted by varying EGR injection velocity and direct EGR injector diameter performed with under two conditions with non-combustion and combustion. n-heptane (C7H16) is used as surrogate fuel together with 57 species 290 semi-detailed chemical kinetic model developed by Chalmers University is used for combustion simulation. Simulation result indicates viability of co-axial EGR injection as a method for low temperature combustion control.

  2. Effect of elevated temperature on extended enzyme synthesis induced by bacteriophage T4 amber mutants unable to synthesize deoxyribonucleic acid.

    Science.gov (United States)

    Goz, B

    1971-03-01

    The extended synthesis of early enzymes by the deoxyribonucleic acid-negative amber mutants of bacteriophage T4 after infection of the nonpermissive host Escherichia coli B was prevented by incubating the infected cells at 44 C. This effect did not occur if the incubation temperature was 43 C or less or if the cells were grown and infected in broth rather than minimal medium (C medium). Once early enzyme synthesis had ceased at 44 C, lowering the incubation temperature to 37 C did not occasion resumption of synthesis. Experiments with chloramphenicol at 44 C indicated that increased degradation of early enzymes is an unlikely explanation for the effect. Examination of pulse-labeled ribonucleic acid and polysomes made at 37 and 44 C in infected cells revealed some differences, but at present there is no obvious way in which these differences may be related to the effect on enzyme formation. There was no discernible difference between the ribosomal ribonucleic acid and ribosomes at the two temperatures, nor was there a difference in the cell-free amino acid-incorporating systems isolated from cells infected at the two temperatures as judged by polyuridylic stimulation of phenylalanine incorporation. Incubation of cells infected with T4amN82 at 44 C with protein synthesis blocked by 5-methyltryptophan for 15 min did not prevent the typical pattern of enzyme synthesis at 44 C when the block was reversed by excess l-tryptophan. The relation of this and other observations relative to the effect at 44 C on the synthesis of early enzymes is discussed.

  3. Ambient temperature aqueous synthesis of ultrasmall copper doped ceria nanocrystals for the water gas shift and carbon monoxide oxidation reactions

    Energy Technology Data Exchange (ETDEWEB)

    Curran, Christopher D. [Department of Chemical and Biomolecular Engineering; Lehigh University; Bethlehem; USA; Lu, Li [Department of Materials Science and Engineering; Lehigh University; Bethlehem; USA; Kiely, Christopher J. [Department of Chemical and Biomolecular Engineering; Lehigh University; Bethlehem; USA; Department of Materials Science and Engineering; McIntosh, Steven [Department of Chemical and Biomolecular Engineering; Lehigh University; Bethlehem; USA

    2018-01-01

    Ultra-small CuxCe1-xO2-δnanocrystals were prepared through a room temperature, aqueous synthesis method, achieving high copper doping and low water gas shift activation energy.

  4. Room Temperature InP DFB Laser Array Directly Grown on (001) Silicon

    CERN Document Server

    Wang, Zhechao; Pantouvaki, Marianna; Guo, Weiming; Absil, Philippe; Van Campenhout, Joris; Merckling, Clement; Van Thourhout, Dries

    2015-01-01

    Fully exploiting the silicon photonics platform requires a fundamentally new approach to realize high-performance laser sources that can be integrated directly using wafer-scale fabrication methods. Direct band gap III-V semiconductors allow efficient light generation but the large mismatch in lattice constant, thermal expansion and crystal polarity makes their epitaxial growth directly on silicon extremely complex. Here, using a selective area growth technique in confined regions, we surpass this fundamental limit and demonstrate an optically pumped InP-based distributed feedback (DFB) laser array grown on (001)-Silicon operating at room temperature and suitable for wavelength-division-multiplexing applications. The novel epitaxial technology suppresses threading dislocations and anti-phase boundaries to a less than 20nm thick layer not affecting the device performance. Using an in-plane laser cavity defined by standard top-down lithographic patterning together with a high yield and high uniformity provides ...

  5. Simulation of the temperature increase in porcine cadaver iris during direct illumination by femtosecond laser pulses

    Science.gov (United States)

    Sun, Hui; Kurtz, Ronald M.; Juhasz, Tibor

    2012-03-01

    As a model for laser exposure of the iris during femtosecond corneal surgery, we simulated the temperature rise in porcine cadaver iris during direct illumination by the femtosecond laser. The temperature increase induced by a 60 kHz iFS Advanced Femtosecond Laser (AMO Inc., Santa Ana, CA) in porcine cadaver iris was simulated using COMSOL (Comsol Inc., Burlington, MA) finite element software. Temperature increases up to 2.45 °C (corresponding to 2 μJ laser pulse energy and 24 second illumination) were observed in the porcine cadaver iris from the simulation with little variation in temperature profiles compared with specimens for the same laser energy illumination in experiment. : The commercial iFS Advanced Femtosecond Laser operating with pulse energies at approximately the lower limit of the range evaluated in this study would be expected to result in a 1.23 °C temperature increase and, therefore, does not present a safety hazard to the iris.

  6. Evidence that Tropical Forest Photosynthesis is Not Directly Limited by High Temperatures

    Science.gov (United States)

    Smith, M.; Taylor, T.; Van Haren, J. L. M.; Rosolem, R.; Restrepo-Coupe, N.; Wu, J.; Oliveira Junior, R. C.; Silva, R. D.; De Araujo, A. C.; Camargo, P. B. D.; Huxman, T. E.; Saleska, S. R.

    2016-12-01

    Loss of tropical forest biomass under rising temperatures could result in significant feedbacks to global climate. The vulnerability of tropical trees to climate warming depends on the specific physiological mechanisms controlling photosynthetic decline at temperatures above the thermal optimum. High temperatures may negatively impact photosynthetic metabolism (direct effects) (Doughty and Goulden 2008), or leaves may respond to the concomitant increase in vapor pressure deficit (VPD) by closing stomata (indirect effects) (Lloyd and Farquhar 2008). The difference is important because the former reveals a vulnerability of photosynthetic infrastructure to higher temperatures, while the latter is an expected physiological response of healthy leaves. We investigated these contrasting hypotheses in a climate controlled, 0.2 ha artificial tropical forest (the Biosphere 2 tropical forest biome, B2-TF). Typically coupled in nature, VPD and temperature can be varied independently in the controlled environment of the B2-TF, and their effects on photosynthesis distinguished. We found that in the B2-TF, gross ecosystem productivity (GEP) was strongly reduced by increasing VPD, but responded little to temperature. Whereas eddy flux-derived GEP of three natural tropical forest sites in the Amazon of Brazil declined at temperatures above 27°C, GEP in the B2-TF remained stable up to 33°C under both low and high VPD regimes. While either mechanism results in reduced photosynthesis, the impact of VPD is short-lived and may be mitigated by enhanced water use efficiency under elevated atmospheric CO2 concentrations, allowing tropical forests to be more resilient to climate warming.

  7. Direct synthesis of ultrathin SOI structure by extremely low-energy oxygen implantation

    Energy Technology Data Exchange (ETDEWEB)

    Hoshino, Yasushi, E-mail: yhoshino@kanagawa-u.ac.jp; Yachida, Gosuke; Inoue, Kodai; Toyohara, Taiga; Nakata, Jyoji [Department of mathematics and physics, Kanagawa University, 2946, Tsuchiya, Hiratsuka, Kanagawa 259-1293 (Japan)

    2016-06-15

    We performed extremely low-energy {sup 16}O{sup +} implantation at 10 keV (R{sub p} ∼ 25 nm) followed by annealing aiming at directly synthesizing an ultrathin Si layer separated by a buried SiO{sub 2} layer in Si(001) substrates, and then investigated feasible condition of recrystallization and stabilization of the superficial Si and the buried oxide layer by significantly low temperature annealing. The elemental compositions were analyzed by Rutherford backscattering (RBS) and secondary ion mass spectroscopy (SIMS). The crystallinity of the superficial Si layer was quantitatively confirmed by ananlyzing RBS-channeling spectra. Cross-sectional morphologies and atomic configurations were observed by transmission electron microscope (TEM). As a result, we succeeded in directly synthesizing an ultrathin single-crystalline silicon layer with ≤20 nm thick separated by a thin buried stoichiometric SiO{sub 2} layer with ≤20 nm thick formed by extremely low-energy {sup 16}O{sup +} implantation followed by surprisingly low temperature annealing at 1050{sup ∘} C.

  8. Direct Synthesis of Two Inorganic Catalysts on Carbon Fibres for the Electrocatalytic Oxidation of Water.

    Science.gov (United States)

    Svengren, Henrik; Jansson, Kjell; Grins, Jekabs; Wan, Wei; Torapava, Natallia; Johnsson, Mats

    2017-01-12

    Two electrodes for anodic water oxidation made by direct synthesis of inorganic catalysts onto conductive carbon fibre sheets are evaluated. As catalysts two Co- and Sb-containing phases were tested, that is, Co3 Sb4 O6 F6 and the new compound CoSbO4 . The compounds express large differences in their morphology: CoSbO4 grows as thin needles whereas Co3 Sb4 O6 F6 grows as larger facetted crystals. Despite the smaller surface area the latter compound shows a better catalytic performance. When the compound Co3 Sb4 O6 F6 was used it gave a low increase of +0.028 mV h-1 at an overpotential of η=472 mV after 10 h and a stability of +0.48 mV h-1 at an overpotential of η=488 mV after 60 h. The leakages of Co and Sb were negligible and only <0.001 at % Co and approximately 0.02 at % Sb were detected in the electrolyte. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Microwave synthesis of polymer-embedded Pt-Ru catalyst for direct methanol fuel cell.

    Science.gov (United States)

    Bensebaa, Farid; Farah, Abdiaziz A; Wang, Dashan; Bock, Christina; Du, Xiaomei; Kung, Judy; Le Page, Yvon

    2005-08-18

    Platinum-ruthenium nanoparticles stabilized within a conductive polymer matrix are prepared using microwave heating. Polypyrrole di(2-ethylhexyl) sulfosuccinate, or PPyDEHS, has been chosen for its known electrical conductivity, thermal stability, and solubility in polar organic solvents. A scalable and quick two-step process is proposed to fabricate alloyed nanoparticles dispersed in PPyDEHS. First a mixture of PPyDEHS and metallic precursors is heated in a microwave under reflux conditions. Then the nanoparticles are extracted by centrifugation. Physical characterization by TEM shows that crystalline and monodisperse alloyed nanoparticles with an average size of 2.8 nm are obtained. Diffraction data show that crystallite size is around 2.0 nm. Methanol electro-oxidation data allow us to propose these novel materials as potential candidates for direct methanol fuel cells (DMFC) application. The observed decrease in sulfur content in the polymer upon incorporation of PtRu nanoparticles may have adversely affected the measured catalytic activity by decreasing the conductivity of PPyDEHS. Higher concentration of polymer leads to lower catalyst activity. Design and synthesis of novel conductive polymers is needed at this point to enhance the catalytic properties of these hybrid materials.

  10. Direct Silver Micro Circuit Patterning on Transparent Polyethylene Terephthalate Film Using Laser-Induced Photothermochemical Synthesis

    Directory of Open Access Journals (Sweden)

    Chen-Jui Lan

    2017-02-01

    Full Text Available This study presents a new and improved approach to the rapid and green fabrication of highly conductive microscale silver structures on low-cost transparent polyethylene terephthalate (PET flexible substrate. In this new laser direct synthesis and pattering (LDSP process, silver microstructures are simultaneously synthesized and laid down in a predetermined pattern using a low power continuous wave (CW laser. The silver ion processing solution, which is transparent and reactive, contains a red azo dye as the absorbing material. The silver pattern is formed by photothermochemical reduction of the silver ions induced by the focused CW laser beam. In this improved LDSP process, the non-toxic additive in the transparent ionic solution absorbs energy from a low cost CW visible laser without the need for the introduction of any hazardous chemical process. Tests were carried out to determine the durability of the conductive patterns, and numerical analyses of the thermal and fluid transport were performed to investigate the morphology of the deposited patterns. This technology is an advanced method for preparing micro-scale circuitry on an inexpensive, flexible, and transparent polymer substrate that is fast, environmentally benign, and shows potential for Roll-to-Roll manufacture.

  11. Direct chemical synthesis of MnO2 nanowhiskers on MXene surfaces for supercapacitor applications

    KAUST Repository

    Rakhi, Raghavan Baby

    2016-07-05

    Transition metal carbides (MXenes) are an emerging class of two dimensional (2D) materials with promising electrochemical energy storage performance. Herein, for the first time, by direct chemical synthesis, nanocrystalline ε-MnO2 whiskers were formed on MXene nanosheet surfaces (ε-MnO2/Ti2CTx and ε-MnO2/Ti3C2Tx) to make nanocomposite electrodes for aqueous pseudocapacitors. The ε-MnO2 nanowhiskers increase the surface area of the composite electrode and enhance the specific capacitance by nearly three orders of magnitude compared to pure MXene based symmetric supercapacitors. Combined with enhanced pseudocapacitance, the fabricated ε-MnO2/MXene supercapacitors exhibited excellent cycling stability with ~88% of the initial specific capacitance retained after 10000 cycles which is much higher than pure ε-MnO2 based supercapacitors (~74%). The proposed electrode structure capitalizes on the high specific capacitance of MnO2 and the ability of MXenes to improve conductivity and cycling stability.

  12. The Synthesis of Nanostructured WC-Based Hardmetals Using Mechanical Alloying and Their Direct Consolidation

    Directory of Open Access Journals (Sweden)

    N. Al-Aqeeli

    2014-01-01

    Full Text Available Tungsten carbide- (WC- based hardmetals or cemented carbides represent an important class of materials used in a wide range of industrial applications which primarily include cutting/drilling tools and wear resistant components. The introduction and processing of nanostructured WC-based cemented carbides and their subsequent consolidation to produce dense components have been the subject of several investigations. One of the attractive means of producing this class of materials is by mechanical alloying technique. However, one of the challenging issues in obtaining the right end-product is the possible loss of the nanocrystallite sizes due to the undesirable grain growth during powder sintering step. Many research groups have engaged in multiple projects aiming at exploring the right path of consolidating the nanostructured WC-based powders without substantially loosing the attained nanostructure. The present paper highlights some key issues related to powder synthesis and sintering of WC-based nanostructured materials using mechanical alloying. The path of directly consolidating the powders using nonconventional consolidation techniques will be addressed and some light will be shed on the advantageous use of such techniques. Cobalt-bonded hardmetals will be principally covered in this work along with an additional exposure of the use of other binders in the WC-based hardmetals.

  13. Directional solidification of C8-BTBT films induced by temperature gradients and its application for transistors

    Science.gov (United States)

    Fujieda, Ichiro; Iizuka, Naoki; Onishi, Yosuke

    2015-03-01

    Because charge transport in a single crystal is anisotropic in nature, directional growth of single crystals would enhance device performance and reduce its variation among devices. For an organic thin film, a method based on a temperature gradient would offer advantages in throughput and cleanliness. In experiments, a temperature gradient was established in a spin-coated film of 2,7-dioctyl [1]benzothieno[3,2-b]benzothiophene (C8-BTBT) by two methods. First, a sample was placed on a metal plate bridging two heat stages. When one of the heat stages was cooled, the material started to solidify from the colder region. The melt-solid interface proceeded along the temperature gradient. Cracks were formed perpendicular to the solidification direction. Second, a line-shaped region on the film was continuously exposed to the light from a halogen lamp. After the heat stage was cooled, cracks similar to the first experiment were observed, indicating that the melt-solid interface moved laterally. We fabricated top-contact, bottom-gate transistors with these films. Despite the cracks, field-effect mobility of the transistors fabricated with these films was close to 6 cm2 /Vs and 4 cm2 /Vs in the first and second experiment, respectively. Elimination of cracks would improve charge transport and reduce performance variation among devices. It should be noted that the intense light from the halogen lamp did not damage the C8-BTBT films. The vast knowledge on laser annealing is now available for directional growth of this type of materials. The associated cost would be much smaller because an organic thin film melts at a low temperature.

  14. Monodisperse colloidal gallium nanoparticles: synthesis, low temperature crystallization, surface plasmon resonance and Li-ion storage.

    Science.gov (United States)

    Yarema, Maksym; Wörle, Michael; Rossell, Marta D; Erni, Rolf; Caputo, Riccarda; Protesescu, Loredana; Kravchyk, Kostiantyn V; Dirin, Dmitry N; Lienau, Karla; von Rohr, Fabian; Schilling, Andreas; Nachtegaal, Maarten; Kovalenko, Maksym V

    2014-09-03

    We report a facile colloidal synthesis of gallium (Ga) nanoparticles with the mean size tunable in the range of 12-46 nm and with excellent size distribution as small as 7-8%. When stored under ambient conditions, Ga nanoparticles remain stable for months due to the formation of native and passivating Ga-oxide layer (2-3 nm). The mechanism of Ga nanoparticles formation is elucidated using nuclear magnetic resonance spectroscopy and with molecular dynamics simulations. Size-dependent crystallization and melting of Ga nanoparticles in the temperature range of 98-298 K are studied with X-ray powder diffraction, specific heat measurements, transmission electron microscopy, and X-ray absorption spectroscopy. The results point to delta (δ)-Ga polymorph as a single low-temperature phase, while phase transition is characterized by the large hysteresis and by the large undercooling of crystallization and melting points down to 140-145 and 240-250 K, respectively. We have observed size-tunable plasmon resonance in the ultraviolet and visible spectral regions. We also report stable operation of Ga nanoparticles as anode material for Li-ion batteries with storage capacities of 600 mAh g(-1), 50% higher than those achieved for bulk Ga under identical testing conditions.

  15. Low-temperature solvothermal synthesis of EuS hollow microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Yong; Wang, Hong; Li, Peng; Fu, Yao, E-mail: fuyaozn@126.com; Xing, Mingming; Jiang, Tao; Luo, Xixian, E-mail: luoxixiandl@126.com

    2014-09-15

    Graphical abstract: Synthesis of EuS hollow microspheres at low-temperature via solvothermal method for the first time. - Highlights: • We adopt an improved method to synthesise the (Phen)Eu(Et{sub 2}CNS{sub 2}){sub 3} in deionized water. • We have successfully synthesised the EuS hollow microsphere at 230 °C in acetonitrile. • The price of acetonitrile is more inexpensive, so the price of preparation was reduced. - Abstract: EuS crystals are synthesized by low-temperature solvothermal decomposition of the single source precursor complex (Phen)Eu(Et{sub 2}CNS{sub 2}){sub 3} in acetonitrile. X-ray powder diffraction, scanning electron microscopy, granulocyte diameter statistical analysis, surface energy-dispersive X-ray spectroscopy analysis, and UV–vis absorption spectroscopy are used to characterize the structure and properties of the obtained EuS crystals. The results show that the formed EuS crystals are uniform hollow microspheres with a typical cubic phase structure of rock salt and the average particle size of 2.01 μm. The mechanisms for the thermal decomposition of the precursor complex and the formation of the EuS hollow microspheres are postulated based on the experimental observations and previous reports.

  16. Metabolic adaptation of Escherichia coli during temperature-induced recombinant protein production: 1. Readjustment of metabolic enzyme synthesis.

    Science.gov (United States)

    Hoffmann, Frank; Weber, Jan; Rinas, Ursula

    2002-11-05

    The metabolic burden and the stress load resulting from temperature-induced production of human basic fibroblast growth factor is connected to an increase in the respiratory activity of recombinant Escherichia coli, thereby reducing the biomass yield. To study the underlying changes in metabolic enzyme synthesis rates, the radiolabeled proteom was subjected to two-dimen- sional gel electrophoresis. After temperature-induction, the cAMP-CRP controlled dehydrogenases of the pyruvate dehydrogenase complex and the tricarboxylic acid cycle (LpdA and SdhA) were induced four times, reaching a maximum 1 h after the temperature upshift. The more abundant tricarboxylic acid cycle dehydrogenases (Icd and Mdh) were initially produced at reduced rates but regained preshift rates within 30 min. The adenylate energy charge dropped immediately after the temperature upshift but recovered within 1 h. Similar profiles in dehydrogenase synthesis rates and adenylate energy charge were found in a control cultivation of a strain carrying the "empty" parental expression vector. Although both strains exhibited significant differences in growth pattern and respiration rates after the temperature upshift, the adaptation of the energetic state of the cells and the synthesis of enzymes from the energy-generating catabolic pathway did not seem to be affected by the strong overproduction of the recombinant growth factor. In contrast, the synthesis rates of enzymes belonging to the biosynthetic machinery, e.g., translational elongation factors, decreased more strongly in the culture synthesizing the recombinant protein. In control and producing culture, synthesis rates of elongation factors paralleled the respective growth rate profiles. Thus, cells seem to readjust their metabolic activities according to their energetic requirements and, if necessary, at the cost of their biosynthetic capabilities. Copyright 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 80: 313-319, 2002.

  17. Wireless Capacitive Pressure Sensor With Directional RF Chip Antenna for High Temperature Environments

    Science.gov (United States)

    Scardelletti, M. C.; Jordan, J. L.; Ponchak, G. E.; Zorman, C. A.

    2015-01-01

    This paper presents the design, fabrication and characterization of a wireless capacitive pressure sensor with directional RF chip antenna that is envisioned for the health monitoring of aircraft engines operating in harsh environments. The sensing system is characterized from room temperature (25 C) to 300 C for a pressure range from 0 to 100 psi. The wireless pressure system consists of a Clapp-type oscillator design with a capacitive MEMS pressure sensor located in the LC-tank circuit of the oscillator. Therefore, as the pressure of the aircraft engine changes, so does the output resonant frequency of the sensing system. A chip antenna is integrated to transmit the system output to a receive antenna 10 m away.The design frequency of the wireless pressure sensor is 127 MHz and a 2 increase in resonant frequency over the temperature range of 25 to 300 C from 0 to 100 psi is observed. The phase noise is less than minus 30 dBcHz at the 1 kHz offset and decreases to less than minus 80 dBcHz at 10 kHz over the entire temperature range. The RF radiation patterns for two cuts of the wireless system have been measured and show that the system is highly directional and the MEMS pressure sensor is extremely linear from 0 to 100 psi.

  18. The Effects of Light and Temperature on Biotin Synthesis in Pea Sprouts.

    Science.gov (United States)

    Kamiyama, Shin; Ohnuki, Risa; Moriki, Aoi; Abe, Megumi; Ishiguro, Mariko; Sone, Hideyuki

    2016-01-01

    Biotin is an essential micronutrient, and is a cofactor for several carboxylases that are involved in the metabolism of glucose, fatty acids, and amino acids. Because plant cells can synthesize their own biotin, a wide variety of plant-based foods contains significant amounts of biotin; however, the influence of environmental conditions on the biotin content in plants remains largely unclear. In the present study, we investigated the effects of different cultivation conditions on the biotin content and biotin synthesis in pea sprouts (Pisum sativum). In the experiment, the pea sprouts were removed from their cotyledons and cultivated by hydroponics under five different lighting and temperature conditions (control [25ºC, 12-h light/12-h dark cycle], low light [25ºC, 4-h light/20-h dark cycle], dark [25ºC, 24 h dark], low temperature [12ºC, 12-h light/12-h dark cycle], and cold [6ºC, 12-h light/12-h dark cycle]) for 10 d. Compared to the biotin content of pea sprouts under the control conditions, the biotin contents of pea sprouts under the low-light, dark, and cold conditions had significantly decreased. The dark group showed the lowest biotin content among the groups. Expression of the biotin synthase gene (bio2) was also significantly decreased under the dark and cold conditions compared to the control condition, in a manner similar to that observed for the biotin content. No significant differences in the adenosine triphosphate content were observed among the groups. These results indicate that environmental conditions such as light and temperature modulate the biotin content of pea plant tissues by regulating the expression of biotin synthase.

  19. Direct-Imaging-Based Quantification of Bacillus cereus ATCC 14579 Population Heterogeneity at a Low Incubation Temperature

    NARCIS (Netherlands)

    Besten, den H.M.W.; Garcia, D.; Moezelaar, R.; Zwietering, M.H.; Abee, T.

    2010-01-01

    Bacillus cereus ATCC 14579 was cultured in microcolonies on Anopore strips near its minimum growth temperature to directly image and quantify its population heterogeneity at an abusive refrigeration temperature. Eleven percent of the microcolonies failed to grow during low-temperature incubation,

  20. ACBC to Balcite: Bioinspired Synthesis of a Highly Substituted High-Temperature Phase from an Amorphous Precursor.

    Science.gov (United States)

    Whittaker, Michael L; Joester, Derk

    2017-07-01

    Energy-efficient synthesis of materials locked in compositional and structural states far from equilibrium remains a challenging goal, yet biomineralizing organisms routinely assemble such materials with sophisticated designs and advanced functional properties, often using amorphous precursors. However, incorporation of organics limits the useful temperature range of these materials. Herein, the bioinspired synthesis of a highly supersaturated calcite (Ca0.5 Ba0.5 CO3 ) called balcite is reported, at mild conditions and using an amorphous calcium-barium carbonate (ACBC) (Ca1-x Ba x CO3 ·1.2H2 O) precursor. Balcite not only contains 50 times more barium than the solubility limit in calcite but also displays the rotational disorder on carbonate sites that is typical for high-temperature calcite. It is significantly harder (30%) and less stiff than calcite, and retains these properties after heating to elevated temperatures. Analysis of balcite local order suggests that it may require the formation of the ACBC precursor and could therefore be an example of nonclassical nucleation. These findings demonstrate that amorphous precursor pathways are powerfully enabling and provide unprecedented access to materials far from equilibrium, including high-temperature modifications by room-temperature synthesis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. ACBC to Balcite: Bioinspired Synthesis of a Highly Substituted High-Temperature Phase from an Amorphous Precursor

    Energy Technology Data Exchange (ETDEWEB)

    Whittaker, Michael L.; Joester, Derk (NWU)

    2017-04-28

    Energy-efficient synthesis of materials locked in compositional and structural states far from equilibrium remains a challenging goal, yet biomineralizing organisms routinely assemble such materials with sophisticated designs and advanced functional properties, often using amorphous precursors. However, incorporation of organics limits the useful temperature range of these materials. Herein, the bioinspired synthesis of a highly supersaturated calcite (Ca0.5Ba0.5CO3) called balcite is reported, at mild conditions and using an amorphous calcium–barium carbonate (ACBC) (Ca1- x Ba x CO3·1.2H2O) precursor. Balcite not only contains 50 times more barium than the solubility limit in calcite but also displays the rotational disorder on carbonate sites that is typical for high-temperature calcite. It is significantly harder (30%) and less stiff than calcite, and retains these properties after heating to elevated temperatures. Analysis of balcite local order suggests that it may require the formation of the ACBC precursor and could therefore be an example of nonclassical nucleation. These findings demonstrate that amorphous precursor pathways are powerfully enabling and provide unprecedented access to materials far from equilibrium, including high-temperature modifications by room-temperature synthesis.

  2. In situ probing of temperature in radio frequency thermal plasma using Yttrium ion emission lines during synthesis of yttria nanoparticles

    Science.gov (United States)

    Dhamale, G. D.; Tiwari, N.; Mathe, V. L.; Bhoraskar, S. V.; Ghorui, S.

    2017-07-01

    Particle feeding is used in the most important applications of radio frequency (r.f.) thermal plasmas like synthesis of nanoparticles and particle spheroidization. The study reports an in-situ investigation of radial distribution of temperature in such devices using yttrium ion emission lines under different rates of particle loading during synthesis of yttria nanoparticles. A number of interesting facts about the response of r.f. plasma to the rate of particle loading, hitherto unknown, are revealed. Observed phenomena are supported with experimental data from fast photographic experiments and actual synthesis results. The use of the Abel inversion technique together with simultaneous multi-track acquisition of emission spectra from different spatial locations using a CCD based spectrometer allowed us to extract accurate distribution of temperature inside the plasma in the presence of inherent instabilities. The temperature profiles of this type of plasma have been measured possibly for the first time while particles are being fed into the plasma. Observed changes in the temperature profiles as the particle feed rate increases are very significant. Reaction forces resulting from particle evaporation, and increased skin depth owing to the decrease in electrical conductivity in the edge region are proposed as the two different mechanisms to account for the observed changes in the temperature profile as the powder feed rate is increased. Quantitative analyses supporting the proposed mechanisms are presented.

  3. Low-temperature hydrothermal synthesis of the three-layered sodium cobaltite P3-Na{sub x}CoO{sub 2} (x ∼ 0.60)

    Energy Technology Data Exchange (ETDEWEB)

    Miclau, M., E-mail: marinela.miclau@gmail.com [National Institute for Research and Development in Electrochemistry and Condensed Matter, Timisoara, 1 Plautius Andronescu, 300224, Timisoara (Romania); Bokinala, K. [National Institute for Research and Development in Electrochemistry and Condensed Matter, Timisoara, 1 Plautius Andronescu, 300224, Timisoara (Romania); CNRS, Université de Bordeaux, ICMCB, 87 avenue du Dr. A. Schweitzer, Pessac, F-33608 (France); Politehnica University of Timisoara, Pta Victoriei No. 2, 300006, Timisoara (Romania); Miclau, N. [Politehnica University of Timisoara, Pta Victoriei No. 2, 300006, Timisoara (Romania)

    2014-06-01

    Highlights: • We report direct synthesis of the high temperature stable phase, P3-Na{sub 0.6}CoO{sub 2}. • The hydrothermal synthesis of P3-Na{sub 0.6}CoO{sub 2} involves one step and low temperature. • The yield diagram for Na–Co–H{sub 2}O system has been builded up to 250 °C. • We propose a formation mechanism of P3-Na{sub 0.6}CoO{sub 2} phase using the unit cell theory. • The thermal stability of P3-Na{sub 0.6}CoO{sub 2} has been investigated by means of HT-XRD. - Abstract: In order to obtain the layered sodium cobalt oxide materials by hydrothermal synthesis, the yield diagram for Na–Co–H{sub 2}O system has been built and studied. In the same time, the well-known data of Co–H{sub 2}O system have been extended at 250 °C in basic solution. We had first synthesized directly the high temperature stable phase, P3-Na{sub 0.6}CoO{sub 2} by a one-step low-temperature hydrothermal method. The rhombohedral structure of P3-Na{sub 0.6}CoO{sub 2} has been determined by X-ray diffraction (XRD) and the purity of phases has been confirmed by XPS. The thermal stability of P3-Na{sub 0.6}CoO{sub 2} has been investigated by means of high temperature X-ray diffraction in 298–873 K range and when the temperature has reached 723 K, the completely transformation of P3-Na{sub 0.6}CoO{sub 2} in the rhombohedral stable phase α-NaCoO{sub 2} (space group R-3m) was observed. Also, a formation mechanism of P3-Na{sub 0.6}CoO{sub 2} phase using the unit cell theory in the hydrothermal process was proposed.

  4. The effect of temperature on the output characteristics of micro direct methanol fuel cell

    Science.gov (United States)

    Yuan, Zhenyu; Yang, Jie

    2015-07-01

    In this paper, the effects of operating temperature on mass transport and micro direct methanol fuel cell (μDMFC) performance are presented. Furthermore, a whole two-dimensional model coupled with mass/momentum transports and temperature characteristic is established. Simulation results show that the temperature has significant effects on methanol concentration/CO2 distributions, crossover current density, and the polarization curve. The metal-based μDMFC with the effective area of 0.64 cm2 is fabricated using micro-stamping technology, and the detailed experimental validation is conducted. The results reveal that when the cell is supplied with a relatively low aqueous methanol flow rate, the peak power density exhibits a trend of initially going up, reaching the peak value of 85.3 mW cm-2 at 60 °C, and then dropping off. At the higher flow rate, however, a proportional relationship between the power density and temperature is obtained. The experimental results are in good agreement with the simulation.

  5. Effect of reactor temperature on direct growth of carbon nanomaterials on stainless steel

    Science.gov (United States)

    Edzatty, A. N.; Syazwan, S. M.; Norzilah, A. H.; Jamaludin, S. B.

    2016-07-01

    Currently, carbon nanomaterials (CNMs) are widely used for various applications due to their extraordinary electrical, thermal and mechanical properties. In this work, CNMs were directly grown on the stainless steel (SS316) via chemical vapor deposition (CVD). Acetone was used as a carbon source and argon was used as carrier gas, to transport the acetone vapor into the reactor when the reaction occurred. Different reactor temperature such as 700, 750, 800, 850 and 900 °C were used to study their effect on CNMs growth. The growth time and argon flow rate were fixed at 30 minutes and 200 ml/min, respectively. Characterization of the morphology of the SS316 surface after CNMs growth using Scanning Electron Microscopy (SEM) showed that the diameter of grown-CNMs increased with the reactor temperature. Energy Dispersive X-ray (EDX) was used to analyze the chemical composition of the SS316 before and after CNMs growth, where the results showed that reduction of catalyst elements such as iron (Fe) and nickel (Ni) at high temperature (700 - 900 °C). Atomic Force Microscopy (AFM) analysis showed that the nano-sized hills were in the range from 21 to 80 nm. The best reactor temperature to produce CNMs was at 800 °C.

  6. Size-selective synthesis of ultrasmall hydrophilic CdSe nanoparticles in aqueous solution at room temperature.

    Science.gov (United States)

    Park, Yeon-Su; Okamoto, Yukihiro; Kaji, Noritada; Tokeshi, Manabu; Baba, Yoshinobu

    2012-01-01

    Hydrophilic semiconductor nanoparticles are very attractive for various biological applications, such as in optical sensing, tracing, and imaging of biological molecules-of-interest, because of their broad excitation wavelength, tunable emission wavelength, strong photoluminescence, and relatively high stability against photobleaching and chemicals. Compared to organic phase synthesis and subsequent surface modification, aqueous phase synthesis approaches provide multiple advantages for obtaining hydrophilic semiconductor nanoparticles. Here, we describe methods for the size-selective growth and stabilization of ultrasmall hydrophilic CdSe nanoparticles in aqueous solution at room temperature by using amino acid cysteine or one of its derivatives as a surface capping agent.

  7. NiO/CeO2-ZnO nano-catalysts for direct synthesis of dimethyl carbonate from methanol and carbon dioxide.

    Science.gov (United States)

    Kang, Ki Hyuk; Lee, Chang Hoon; Kim, Dong Baek; Jang, Boknam; Song, In Kyu

    2014-11-01

    XNiO/CeO2(0.7)-ZnO(0.3) (X = 0, 1, 5, 10, and 15) nano-catalysts were prepared by a wet impregnation method with a variation of NiO content (X, wt%). The prepared catalysts were then applied to the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Successful formation of XNiO/CeO2(0.7)-ZnO(0.3) nano-catalysts was confirmed by XRD and ICP-AES analyses. Acidity and basicity of XNiO/CeO2-ZnO were measured by NH3-TPD (temperature-programmed desorption) and CO2-TPD experiments, respectively, with an aim of elucidating the effect of acidity and basicity of the catalysts on the catalytic performance in the reaction. It was revealed that the catalytic activity of XNiO/CeO2(0.7)-ZnO(0.3) was closely related to both acidity and basicity of the catalysts. The amount of dimethyl carbonate produced over XNiO/CeO2(0.7)-ZnO(0.3) increased with increasing acidity and basicity of the catalysts. Thus, both acidity and basicity of the catalysts played important roles in determining the catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide.

  8. Kinetically controlled synthesis of large-scale morphology-tailored silver nanostructures at low temperature

    Science.gov (United States)

    Zhang, Ling; Zhao, Yuda; Lin, Ziyuan; Gu, Fangyuan; Lau, Shu Ping; Li, Li; Chai, Yang

    2015-08-01

    Ag nanostructures are widely used in catalysis, energy conversion and chemical sensing. Morphology-tailored synthesis of Ag nanostructures is critical to tune physical and chemical properties. In this study, we develop a method for synthesizing the morphology-tailored Ag nanostructures in aqueous solution at a low temperature (45 °C). With the use of AgCl nanoparticles as the precursor, the growth kinetics of Ag nanostructures can be tuned with the pH value of solution and the concentration of Pd cubes which catalyze the reaction. Ascorbic acid and cetylpyridinium chloride are used as the mild reducing agent and capping agent in aqueous solution, respectively. High-yield Ag nanocubes, nanowires, right triangular bipyramids/cubes with twinned boundaries, and decahedra are successfully produced. Our method opens up a new environmentally-friendly and economical route to synthesize large-scale and morphology-tailored Ag nanostructures, which is significant to the controllable fabrication of Ag nanostructures and fundamental understanding of the growth kinetics.Ag nanostructures are widely used in catalysis, energy conversion and chemical sensing. Morphology-tailored synthesis of Ag nanostructures is critical to tune physical and chemical properties. In this study, we develop a method for synthesizing the morphology-tailored Ag nanostructures in aqueous solution at a low temperature (45 °C). With the use of AgCl nanoparticles as the precursor, the growth kinetics of Ag nanostructures can be tuned with the pH value of solution and the concentration of Pd cubes which catalyze the reaction. Ascorbic acid and cetylpyridinium chloride are used as the mild reducing agent and capping agent in aqueous solution, respectively. High-yield Ag nanocubes, nanowires, right triangular bipyramids/cubes with twinned boundaries, and decahedra are successfully produced. Our method opens up a new environmentally-friendly and economical route to synthesize large-scale and morphology

  9. Direct-contact high-temperature thermal energy storage heat exchanger

    Science.gov (United States)

    Alario, J. P.; Brown, R.

    1983-09-01

    A 10 kWh scale model high temperature direct contact latent heat exchange thermal energy storage system was fabricated. A research program was structured in three separate phases: (1) the inspection and evaluation of the original hardware, which suffered extensive corrosion and damage in a previous experimental program; (2) redesign and fabrication of a modified system, and (3) detailed test evaluation. In phase 1, the design was modified to eliminate previous deficiencies. Phase 2 entailed component procurement and fabrication, system assembly, and instrumentation. The results for the design and fabrication phases of the program are presented.

  10. Modeling directional effects in land surface temperature derived from geostationary satellite data

    DEFF Research Database (Denmark)

    Rasmussen, Mads Olander

    This PhD-thesis investigates the directional effects in land surface temperature (LST) estimates from the SEVIRI sensor onboard the Meteosat Second Generation (MSG) satellites. The directional effects are caused by the land surface structure (i.e. tree size and shape) interacting with the changing...... in terms of timing than the uncertainties in data from polar orbiting sensors, which will cause discrepancies between measurements from the two types of sensors. An assessment of the performance of current LST algorithms from MSG SEVIRI for semi-arid West Africa was carried out, using data from two field...... sites in Senegal and Mali. The agreement between the satellite and ground data for the rainy season was generally discouraging with biases exceeding 5 K, while there were indications that performance is much better during the dry season. The large discrepancies are thought to be caused by insufficient...

  11. Direct Selective Laser Sintering/Melting of High Density Alumina Powder Layers at Elevated Temperatures

    Science.gov (United States)

    Deckers, J.; Meyers, S.; Kruth, J. P.; Vleugels, J.

    Direct selective laser sintering (SLS) or selective laser melting (SLM) are additive manufacturing techniques that can be used to produce three-dimensional ceramic parts directly, without the need for a sacrificial binder. In this paper, a low laser energy density is applied to SLS/SLM high density powder layers of sub-micrometer alumina at elevated temperatures (up to 800̊C). In order to achieve this, a furnace was designed and built into a commercial SLS machine. This furnace was able to produce a homogeneously heated cylindrical zone with a height of 60 mm and a diameter of 32 mm. After optimizing the layer deposition and laser scanning parameters, two ceramic parts with a density up to 85% and grain sizes as low as 5 μm were successfully produced.

  12. The Influence of Synthesis Temperature on Manufacturing and Properties of SrSi2O2N2:Eu2+ Powders

    Directory of Open Access Journals (Sweden)

    Pawlik T.

    2017-06-01

    Full Text Available This paper presents the results of the synthesis temperature on the properties of the ceramic powders of SrSi2O2N2:Eu2+ obtained by the solid-phase reaction. Synthesis was carried out in the temperature range of 1250-1650°C for 2 hours in nitrogen flow in the reducing atmosphere of the graphite furnace. The phases present in the resultant powders were identified by X-ray structural analysis (XRD. Scanning electron microscopy (SEM was used to examine the changes in the powder morphology as a result of the synthesis. The excitation and emission spectra measurements let to study phosphor photoluminescence properties. The results show the strong influence of temperature synthesis on the formation and purity of expected phases. The synthesis temperature also affects the luminescent properties of SrSi2O2N2:Eu2+ ceramic powders.

  13. Synthesis of Non-molecular Nitrogen Phases at Mbar Pressures by Direct Laser-heating

    Energy Technology Data Exchange (ETDEWEB)

    Lipp, M J; Klepeis, J P; Baer, B J; Cynn, H; Evans, W J; Iota, V; Yoo, C

    2007-03-26

    Direct laser heating of molecular N2 to above 1400 K at 120-130 GPa results in the formation of a reddish amorphous phase and a transparent crystalline solid above 2000 K. Raman and x-ray data confirm that the transparent phase is cubic-gauche nitrogen (cg-N), while the reddish color of the amorphous phase might indicate the presence of N=N dish bonds. The quenched amorphous phase is stable down to at least 70GPa, analogous to cg-N, and could be a new non-molecular phase or an extension of the already known {eta}-phase. A chemo-physical phase diagram is presented which emphasizes the difference between pressure- and temperature-induced transitions from molecular to non-molecular solids, as found in other low Z systems.

  14. Direct writing of flexible electronics through room temperature liquid metal ink.

    Science.gov (United States)

    Gao, Yunxia; Li, Haiyan; Liu, Jing

    2012-01-01

    Conventional approaches of making a flexible circuit are generally complex, environment unfriendly, time and energy consuming, and thus expensive. Here, we describe for the first time the method of using high-performance GaIn(10)-based electrical ink, a significantly neglected room temperature liquid metal, as both electrical conductors and interconnects, for directly writing flexible electronics via a rather easy going and cost effective way. The new generation electric ink was made and its wettability with various materials was modified to be easily written on a group of either soft or rigid substrates such as epoxy resin board, glass, plastic, silica gel, paper, cotton, textiles, cloth and fiber etc. Conceptual experiments were performed to demonstrate and evaluate the capability of directly writing the electrical circuits via the invented metal ink. Mechanisms involved were interpreted through a series of fundamental measurements. The electrical resistivity of the fluid like GaIn(10)-based material was measured as 34.5 µΩ·cm at 297 K by four point probe method and increased with addition of the oxygen quantity, which indicates it as an excellent metal ink. The conductive line can be written with features that are approximately 10 µm thick. Several functional devices such as a light emitting diode (LED) array showing designed lighting patterns and electrical fan were made to work by directly writing the liquid metal on the specific flexible substrates. And satisfactory performances were obtained. The present method opens the way to directly and quickly writing flexible electronics which can be as simple as signing a name or drawing a picture on the paper. The unique merit of the GaIn(10)-based liquid metal ink lies in its low melting temperature, well controlled wettability, high electrical conductivity and good biocompability. The new electronics writing strategy and basic principle has generalized purpose and can be extended to more industrial areas, even

  15. Direct Writing of Flexible Electronics through Room Temperature Liquid Metal Ink

    Science.gov (United States)

    Gao, Yunxia; Li, Haiyan; Liu, Jing

    2012-01-01

    Background Conventional approaches of making a flexible circuit are generally complex, environment unfriendly, time and energy consuming, and thus expensive. Here, we describe for the first time the method of using high-performance GaIn10-based electrical ink, a significantly neglected room temperature liquid metal, as both electrical conductors and interconnects, for directly writing flexible electronics via a rather easy going and cost effective way. Methods The new generation electric ink was made and its wettability with various materials was modified to be easily written on a group of either soft or rigid substrates such as epoxy resin board, glass, plastic, silica gel, paper, cotton, textiles, cloth and fiber etc. Conceptual experiments were performed to demonstrate and evaluate the capability of directly writing the electrical circuits via the invented metal ink. Mechanisms involved were interpreted through a series of fundamental measurements. Results The electrical resistivity of the fluid like GaIn10-based material was measured as 34.5 µΩ·cm at 297 K by four point probe method and increased with addition of the oxygen quantity, which indicates it as an excellent metal ink. The conductive line can be written with features that are approximately 10 µm thick. Several functional devices such as a light emitting diode (LED) array showing designed lighting patterns and electrical fan were made to work by directly writing the liquid metal on the specific flexible substrates. And satisfactory performances were obtained. Conclusions The present method opens the way to directly and quickly writing flexible electronics which can be as simple as signing a name or drawing a picture on the paper. The unique merit of the GaIn10-based liquid metal ink lies in its low melting temperature, well controlled wettability, high electrical conductivity and good biocompability. The new electronics writing strategy and basic principle has generalized purpose and can be

  16. Direct writing of flexible electronics through room temperature liquid metal ink.

    Directory of Open Access Journals (Sweden)

    Yunxia Gao

    Full Text Available BACKGROUND: Conventional approaches of making a flexible circuit are generally complex, environment unfriendly, time and energy consuming, and thus expensive. Here, we describe for the first time the method of using high-performance GaIn(10-based electrical ink, a significantly neglected room temperature liquid metal, as both electrical conductors and interconnects, for directly writing flexible electronics via a rather easy going and cost effective way. METHODS: The new generation electric ink was made and its wettability with various materials was modified to be easily written on a group of either soft or rigid substrates such as epoxy resin board, glass, plastic, silica gel, paper, cotton, textiles, cloth and fiber etc. Conceptual experiments were performed to demonstrate and evaluate the capability of directly writing the electrical circuits via the invented metal ink. Mechanisms involved were interpreted through a series of fundamental measurements. RESULTS: The electrical resistivity of the fluid like GaIn(10-based material was measured as 34.5 µΩ·cm at 297 K by four point probe method and increased with addition of the oxygen quantity, which indicates it as an excellent metal ink. The conductive line can be written with features that are approximately 10 µm thick. Several functional devices such as a light emitting diode (LED array showing designed lighting patterns and electrical fan were made to work by directly writing the liquid metal on the specific flexible substrates. And satisfactory performances were obtained. CONCLUSIONS: The present method opens the way to directly and quickly writing flexible electronics which can be as simple as signing a name or drawing a picture on the paper. The unique merit of the GaIn(10-based liquid metal ink lies in its low melting temperature, well controlled wettability, high electrical conductivity and good biocompability. The new electronics writing strategy and basic principle has generalized

  17. Experimental determination and modeling of the phase behavior for the direct synthesis of dimethyl carbonate from methanol and carbon dioxide

    DEFF Research Database (Denmark)

    Tsivintzelis, Ioannis; Musko, Nikolai E.; Baiker, Alfons

    2013-01-01

    This study focuses on the investigation of the phase behavior of mixtures relevant to the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. The bubble points of corresponding quaternary mixtures of varying composition were experimentally determined. The Cubic-Plus-Associati......This study focuses on the investigation of the phase behavior of mixtures relevant to the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. The bubble points of corresponding quaternary mixtures of varying composition were experimentally determined. The Cubic....... The results reveal P–T regions where the system can exist in one single phase and where it is multiphase, which can be used for further optimization not only of the chemical reaction itself but also subsequent product separation processes....

  18. Low Temperature Synthesis of Li2SiO3: Effect on Its Morphological and Textural Properties

    Directory of Open Access Journals (Sweden)

    Georgina Mondragón-Gutiérrez

    2008-01-01

    Full Text Available Synthesis, at low temperature, of Li2SiO3 was investigated using different Li : Si molar ratios and urea, which was used as template. This new synthesis was performed in order to look for different textural and morphological properties than those obtained usually by conventional methods in this kind of ceramics. XRD and SEM analyses showed that Li2SiO3 was obtained pure and with ceramic particle morphology of hollow spheres of 2–6 μm. TEM analysis showed that those spheres were composed by needle-like particles crosslinked among them. This morphology provided a high surface area, probed by N2 adsorption. Therefore, this method of synthesis may be used to obtain other similar ceramics and test them in different applications.

  19. One-step room temperature synthesis of very small γ-Fe{sub 2}O{sub 3} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Moscoso-Londoño, O. [Laboratorio de Sólidos Amorfos, INTECIN, Facultad de Ingeniería, Universidad de Buenos Aires, C1063ACV, Buenos Aires (Argentina); Carrião, M.S. [Laboratorio de Sólidos Amorfos, INTECIN, Facultad de Ingeniería, Universidad de Buenos Aires, C1063ACV, Buenos Aires (Argentina); Instituto de Física, Campus II, Universidade Federal de Goiás, CEP: 74001-970 Goiânia (GO) (Brazil); Cosio-Castañeda, C. [Laboratorio de Sólidos Amorfos, INTECIN, Facultad de Ingeniería, Universidad de Buenos Aires, C1063ACV, Buenos Aires (Argentina); Departamento de Física y Química Teórica, Facultad de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, D.F. 04510 (Mexico); Bilovol, V. [Laboratorio de Sólidos Amorfos, INTECIN, Facultad de Ingeniería, Universidad de Buenos Aires, C1063ACV, Buenos Aires (Argentina); Sánchez, R. Martínez [Instituto de Materiales y Reactivos, Universidad de La Habana, CP10400, Ciudad Habana (Cuba); Lede, E.J.; Socolovsky, L.M. [Laboratorio de Sólidos Amorfos, INTECIN, Facultad de Ingeniería, Universidad de Buenos Aires, C1063ACV, Buenos Aires (Argentina); Martínez-García, R., E-mail: rmartinez@fi.uba.ar [Laboratorio de Sólidos Amorfos, INTECIN, Facultad de Ingeniería, Universidad de Buenos Aires, C1063ACV, Buenos Aires (Argentina)

    2013-09-01

    Graphical abstract: - Highlights: • One-step synthesis of 3 nm maghemite nanoparticles is reported. • Maghemite nanoparticles can be synthesized from a ferric solution. • γ-Fe{sub 2}O{sub 3} NPs can be obtained if the precursor has Fe(III) in tetrahedral interstices. • HR-TEM, Mössbauer, XAFS and magnetometry analysis proved the maghemite existence - Abstract: Very small maghemite nanoparticles (∼3 nm) are obtained through a one-step synthesis at room temperature. The fast neutralization reaction of a ferric solution in a basic medium produces an intermediate phase, presumably two-line ferrihydrite, which in oxidizing conditions is transformed to maghemite nanoparticles. The synthesis of maghemite, as final product of the reaction, was characterized by High-Resolution Transmission Electron Microscopy (HR-TEM), X-ray Absorption Fine Structure (XAFS), Mössbauer spectroscopy, and magnetometry. The XAFS technique allowed the analysis of the crystallographic variations into maghemite nanoparticles as a result of modification in its surface/volume ratio. Mössbauer spectroscopy at low temperature (4.2 K) confirms the presence of Fe(III) in tetrahedral and octahedral interstices, in the stoichiometry corresponding to maghemite. The specific magnetization, M vs H (3 K and 300 K, up to 7 T) and temperature dependence of the magnetization (50 Oe by ZFC mode, 2 K ≤ T ≤ 300 K) indicate that maghemite nanoparticles of 3 nm are in superparamagnetic state with a blocking temperature close to 36 K.

  20. Black carbon semi-direct effects on cloud cover: review and synthesis

    Directory of Open Access Journals (Sweden)

    D. Koch

    2010-08-01

    Full Text Available Absorbing aerosols (AAs such as black carbon (BC or dust absorb incoming solar radiation, perturb the temperature structure of the atmosphere, and influence cloud cover. Previous studies have described conditions under which AAs either increase or decrease cloud cover. The effect depends on several factors, including the altitude of the AA relative to the cloud and the cloud type. We attempt to categorize the effects into several likely regimes. Cloud cover is decreased if the AAs are embedded in the cloud layer. AAs below cloud may enhance convection and cloud cover. AAs above cloud top stabilize the underlying layer and tend to enhance stratocumulus clouds but may reduce cumulus clouds. AAs can also promote cloud cover in convergent regions as they enhance deep convection and low level convergence as it draws in moisture from ocean to land regions. Most global model studies indicate a regional variation in the cloud response but generally increased cloud cover over oceans and some land regions, with net increased low-level and/or reduced upper level cloud cover. The result is a net negative semi-direct effect feedback from the cloud response to AAs. In some of these climate model studies, the cooling effect of BC due to cloud changes is strong enough to essentially cancel the warming direct effects.

  1. Collapsed polymer-directed synthesis of multicomponent coaxial-like nanostructures

    KAUST Repository

    Huang, Zhiqi

    2016-07-19

    Multicomponent colloidal nanostructures (MCNs) exhibit intriguing topologically dependent chemical and physical properties. However, there remain significant challenges in the synthesis of MCNs with high-order complexity. Here we show the development of a general yet scalable approach for the rational design and synthesis of MCNs with unique coaxial-like construction. The site-preferential growth in this synthesis relies on the selective protection of seed nanoparticle surfaces with locally defined domains of collapsed polymers. By using this approach, we produce a gallery of coaxial-like MCNs comprising a shaped Au core surrounded by a tubular metal or metal oxide shell. This synthesis is robust and not prone to variations in kinetic factors of the synthetic process. The essential role of collapsed polymers in achieving anisotropic growth makes our approach fundamentally distinct from others. We further demonstrate that this coaxial-like construction can lead to excellent photocatalytic performance over conventional core–shell-type MCNs.

  2. Synthesis of new Diamond-like B-C Phases under High Pressure and Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Ming, L. C. [University of Hawaii; Zinin, P. V. [University of Hawaii; Sharma, S. K. [University of Hawaii

    2014-04-22

    A cubic BC3 (c-BC3) phase was synthesized by direct transformation from graphitic phases at a pressure of 39 GPa and temperature of 2200 K in a laser-heated diamond anvil cell (DAC). A combination of x-ray diffraction (XRD), electron diffraction (ED), transmission electron microscopy (TEM) imaging, and electron energy loss spectroscopy (EELS) measurements lead us to conclude that the obtained phase is hetero-nano-diamond, c-BC3. The EELS measurements show that the atoms inside the cubic structure are bonded by sp3 bonds.

  3. Self-propagating high-temperature synthesis brazing for emergency repair

    Science.gov (United States)

    Bai, Yang; Luo, Zhen; Fan, Naifeng; Ao, Sansan

    2011-05-01

    It is of great significance to fast weld and repair damaged parts in electroless and gasless field. So, based on Selfpropagating High-temperature Synthesis (SHS), this paper investigates the SHS brazing of thermit reaction. It is found that the heat obtained by SHS thermit reaction can not melt the base metal, however the silver solder with the melting temperature of 595°C to 605°C can all just melt in the middle of the base metal to achieve SHS brazing. In the experiment, as the surface tension, the molten solder is more likely to wet the slag which is with a larger surface tension, resulting in the poor wettability between solder and base metal. By adding a certain amount of silver brazing flux into the powder can solve the problem of base metal wetting. When the silver brazing flux and the powder are in a ratio of 10:1, solder melt completely, and can be separated with slag, there is a good weld surface. With the increase of silver brazing flux, the slag is more loose and easy to removal. The solder and base metal coating is better. However, with further increase in silver brazing flux, the heat from the reaction reduces, solder can not melt. And with the increase of the powder, the slag and the solder can not be separated. SHS brazing combines the thermit reaction heat with the brazing technology to achieve the low carbon steel welding. Using the heat of thermit reaction to melt the solder then weld the steel can overcome the defects of poor quality of traditional welding which use the reaction products. And the operation is simple. SHS brazing achieve the emergency equipment welding under the condition of no electricity, no gas and equipment.

  4. Effect of Temperature and Mole Ratio on the Synthesis Yield of Rhenium-Tetrofosmin

    Directory of Open Access Journals (Sweden)

    Widyastuti

    2015-08-01

    Full Text Available Technetium-99m (99mTc tetrofosmin is widely used in nuclear medicine as a diagnostic agent for myocardial perfusion and as a tumor imaging agent. As a parenteral preparation it requires an evaluation of its pharmacokinetics and stability in-vivo. Since 99mTc has a short half-life and is only available in very low concentrations, it is impossible to characterize its chemical properties and presence in the body. Due to this reason, only technetium-99 (T1/2 = 5 × 105 years, which is available in macro quantities, or natural rhenium can be used for this purpose. In this study rhenium-188 (188Re tetrofosmin will be synthesized and applied, because non-radioactive Re can be easily obtained. Synthesis and radiochemical purity analysis of carrier-added 188Re-tetrofosmin were carried out as a model to study the in-vivo stability of technetium-99m tetrofosmin. Rhenium-188 was used as a tracer to identify the formation of rhenium tetrofosmin. Rhenium gluconate was synthesized first prior to the formation of rhenium tetrofosmin. The quality of labeling for both rhenium gluconate and rhenium tetrofosmin was analyzed using paper- and thin-layer chromatography, respectively. Rhenium gluconate can be synthesized with high labeling yield within 1 hour, whereas rhenium tetrofosmin was synthesized both in room temperature and in an elevated temperature with various tetrofosmin-to-rhenium mole ratios.The results showed that heating at 95oC led to a higher yield of more than 90% within 30 minutes. Rhenium tetrofosmin could be produced in high radiochemical purity using an excess of tetrofosmin with mole ratio of 2000. It is concluded that rhenium tetrofosmin could be synthesized through the formation of rhenium gluconate, and a higher yield could be obtained in a shorter time by heating process.

  5. Synthesis of thermally evaporated ZnSe thin film at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Taj Muhammad, E-mail: tajakashne@gmail.com [National Institute of Laser and Optronics (NILOP), P.O. Nilore-45650, Islamabad (Pakistan); Mehmood, Muhammad Farhan [Department of Applied Physics, Federal Urdu University of Arts, Science and Technology, Islamabad (Pakistan); Mahmood, Arshad; Shah, A.; Raza, Q.; Iqbal, Amjid; Aziz, U. [National Institute of Laser and Optronics (NILOP), P.O. Nilore-45650, Islamabad (Pakistan)

    2011-07-01

    Zinc selenide (ZnSe) thin film on glass substrates were prepared by thermal evaporation under high vacuum using the quasi-closed volume technique at room temperature (300 {+-} 2 K). The deposited ZnSe properties were assessed via X-ray diffraction, atomic force microscope (AFM), UV-Vis specrophotometry, Raman spectroscopy, photo-luminescence, Fourier transform infrared spectroscopy (FT-IR) and spectroscopic ellipsometry. The X-ray diffraction patterns of the film exhibited reflection corresponding to the cubic (111) phase (2{theta} = 27.20 deg.). This analysis indicated that the sample is polycrystalline and have cubic (Zinc blende) structure. The crystallites were preferentially oriented with the (111) planes parallel to the substrates. The AFM images showed that the ZnSe films have smooth morphology with roughness 6.74 nm. The transmittance spectrum revealed a high transmission of 89% in the infrared region ({>=} 600 nm) and a low transmission of 40% at 450 nm. The maximum transmission of 89.6% was observed at 640 nm. Optical band-gap was calculated from the transmission data of specrophotometry, photo-luminescence and ellipsometry and was 2.76, 2.74 and 2.82 eV respectively. Raman spectroscopic studies revealed two longitudinal optical phonon modes at 252 cm{sup -1} and 500 cm{sup -1}. In photoluminescence study, the luminescence peaks was observed at 452 nm corresponding to band to band emission. FT-IR study illustrated the existence of Zn-Se bonding in ZnSe thin film. The optical constants were calculated using spectroscopic ellipsometry and were determined from the best fit ellipsometric data in the wavelength regime of interest from 370-1000 nm. These results manifested excellent room temperature ZnSe synthesis and characteristics for opto-electronics technologies.

  6. Microwave-assisted synthesis of poly(3-hexylthiophene) via direct oxidation with FeCl{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Nicho, M.E., E-mail: menicho@uaem.mx [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Universidad Autonoma del Estado de Morelos (UAEM), Av. Universidad 1001, Col. Chamilpa, C.P. 62210 Cuernavaca, Morelos (Mexico); Garcia-Escobar, C.H.; Hernandez-Martinez, D. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Universidad Autonoma del Estado de Morelos (UAEM), Av. Universidad 1001, Col. Chamilpa, C.P. 62210 Cuernavaca, Morelos (Mexico); Linzaga-Elizalde, I. [Centro de Investigaciones Quimicas (CIQ) de la UAEM (Mexico); Cadenas-Pliego, G. [Centro de Investigacion en Quimica Aplicada, Saltillo, Coahuila (Mexico)

    2012-09-20

    In this work, CoolMate microwave synthesis system was employed to synthesize soluble poly(3-hexylthiophene) by direct oxidation of 3-hexylthiophene monomer with FeCl{sub 3} as oxidant. P3HT was synthesized varying reaction time by 2 h, 1 h and 0.5 h. According to the results optimal microwave radiation time for synthesis was 1 h. On the other hand, P3HT was synthesized in two different solvents: chloroform (CHCl{sub 3}) and dichloromethane (CH{sub 2}Cl{sub 2}). The obtained yields depend on the solvent and the reaction time used in the synthesis, microwave-assisted synthesis leads to outstanding increase in yield (with dichloromethane solvent). Homogeneous thin films were prepared by spin-coating technique from toluene. Physicochemical characterization of P3HT polymers was carried out: changes in weight molecular distribution and polydispersity were obtained by HPLC (high-performance liquid chromatography); dyads and triads percent were analyzed by NMR (nuclear magnetic resonance). Surface topographical changes were obtained by atomic force microscopy (AFM). AFM images revealed that the surface morphology depends on synthesis method, reaction time and solvent used. Finally the samples were characterized by thermogravimetric analysis (TGA) and ultraviolet-visible analysis (UV-vis). Compared with the traditional method (without microwave), this method provided considerable decrease in the reaction time, both lower polydispersity and molecular weight, less volume of solvents for the synthesis, as well as more alternatives for solvent choice. The results confirmed the versatility of the procedure by microwave, which yields polymeric materials in 1 h and has no adverse effects on the polymers quality.

  7. 2D temperature field measurement in a direct-injection engine using LIF technology

    Science.gov (United States)

    Liu, Yongfeng; Tian, Hongsen; Yang, Jianwei; Sun, Jianmin; Zhu, Aihua

    2011-12-01

    A new multi-spectral detection strategy for temperature laser- induced- fluorescence (LIF) 2-D imaging measurements is reported for high pressure flames in high-speed diesel engine. Schematic of the experimental set-up is outlined and the experimental data on the diesel engine is summarized. Experiment injection system is a third generation Bosch high-pressure common rail featuring a maximum pressure of 160MPa. The injector is equipped with a six-hole nozzle, where each hole has a diameter of 0.124 mm. and slightly offset to the center of the cylinder axis to allow a better cooling of the narrow bridge between the exhaust valves. The measurement system includes a blower, which supplied the intake flow rate, and a prototype single-valve direct injection diesel engine head modified to lay down the swirled-type injector. 14-bit digital CCD cameras are employed to achieve a greater level of accuracy in comparison to the results of previous measurements. The temperature field spatial distributions in the cylinder for different crank angle degrees are carried out in a single direct-injection diesel engine.

  8. Low-Temperature Synthesis of Hierarchical Amorphous Basic Nickel Carbonate Particles for Water Oxidation Catalysis.

    Science.gov (United States)

    Yang, Yisu; Liang, Fengli; Li, Mengran; Rufford, Thomas E; Zhou, Wei; Zhu, Zhonghua

    2015-07-08

    Amorphous nickel carbonate particles are catalysts for the oxygen evolution reaction (OER), which plays a critical role in the electrochemical splitting of water. The amorphous nickel carbonate particles can be prepared at a temperature as low as 60 °C by an evaporation-induced precipitation (EIP) method. The products feature hierarchical pore structures. The mass-normalized activity of the catalysts, measured at an overpotential of 0.35 V, was 55.1 A g(-1) , with a Tafel slope of only 60 mV dec(-1) . This catalytic activity is superior to the performance of crystalline NiOx particles and β-Ni(OH)2 particles, and compares favorably to state-of-the-art RuO2 catalysts. The activity of the amorphous nickel carbonate is remarkably stable during a 10 000 s chronoamperometry test. Further optimization of synthesis parameters reveals that the amorphous structure can be tuned by adjusting the H2 O/Ni ratio in the precursor mixture. These results suggest the potential application of easily prepared hierarchical basic nickel carbonate particles as cheap and robust OER catalysts with high activity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Rapid, room-temperature synthesis of amorphous selenium/protein composites using Capsicum annuum L extract

    Energy Technology Data Exchange (ETDEWEB)

    Li Shikuo; Shen Yuhua; Xie Anjian; Yu Xuerong; Zhang Xiuzhen; Yang Liangbao; Li Chuanhao [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230039 (China)

    2007-10-10

    We describe the formation of amorphous selenium ({alpha}-Se)/protein composites using Capsicum annuum L extract to reduce selenium ions (SeO{sub 3}{sup 2-}) at room temperature. The reaction occurs rapidly and the process is simple and easy to handle. A protein with a molecular weight of 30 kDa extracted from Capsicum annuum L not only reduces the SeO{sub 3}{sup 2-} ions to Se{sup 0}, but also controls the nucleation and growth of Se{sup 0}, and even participates in the formation of {alpha}-Se/protein composites. The size and shell thickness of the {alpha}-Se/protein composites increases with high Capsicum annuum L extract concentration, and decreases with low reaction solution pH. The results suggest that this eco-friendly, biogenic synthesis strategy could be widely used for preparing inorganic/organic biocomposites. In addition, we also discuss the possible mechanism of the reduction of SeO{sub 3}{sup 2-} ions by Capsicum annuum L extract.

  10. Heat Flux and Wall Temperature Estimates for the NASA Langley HIFiRE Direct Connect Rig

    Science.gov (United States)

    Cuda, Vincent, Jr.; Hass, Neal E.

    2010-01-01

    An objective of the Hypersonic International Flight Research Experimentation (HIFiRE) Program Flight 2 is to provide validation data for high enthalpy scramjet prediction tools through a single flight test and accompanying ground tests of the HIFiRE Direct Connect Rig (HDCR) tested in the NASA LaRC Arc Heated Scramjet Test Facility (AHSTF). The HDCR is a full-scale, copper heat sink structure designed to simulate the isolator entrance conditions and isolator, pilot, and combustor section of the HIFiRE flight test experiment flowpath and is fully instrumented to assess combustion performance over a range of operating conditions simulating flight from Mach 5.5 to 8.5 and for various fueling schemes. As part of the instrumentation package, temperature and heat flux sensors were provided along the flowpath surface and also imbedded in the structure. The purpose of this paper is to demonstrate that the surface heat flux and wall temperature of the Zirconia coated copper wall can be obtained with a water-cooled heat flux gage and a sub-surface temperature measurement. An algorithm was developed which used these two measurements to reconstruct the surface conditions along the flowpath. Determinations of the surface conditions of the Zirconia coating were conducted for a variety of conditions.

  11. Rice responses to rising temperatures--challenges, perspectives and future directions.

    Science.gov (United States)

    Jagadish, S V K; Murty, M V R; Quick, W P

    2015-09-01

    Phenotypic plasticity in overcoming heat stress-induced damage across hot tropical rice-growing regions is predominantly governed by relative humidity. Expression of transpiration cooling, an effective heat-avoiding mechanism, will diminish with the transition from fully flooded paddies to water-saving technologies, such as direct-seeded and aerobic rice cultivation, thus further aggravating stress damage. This change can potentially introduce greater sensitivity to previously unaffected developmental stages such as floral meristem (panicle) initiation and spikelet differentiation, and further intensify vulnerability at the known sensitive gametogenesis and flowering stages. More than the mean temperature rise, increased variability and a more rapid increase in nighttime temperature compared with the daytime maximum present a greater challenge. This review addresses (1) the importance of vapour pressure deficit under fully flooded paddies and increased vulnerability of rice production to heat stress or intermittent occurrence of combined heat and drought stress under emerging water-saving rice technologies; (2) the major disconnect with high night temperature response between field and controlled environments in terms of spikelet sterility; (3) highlights the most important mechanisms that affect key grain quality parameters, such as chalk formation under heat stress; and finally (4), we model and estimate heat stress-induced spikelet sterility taking South Asia as a case study. © 2014 John Wiley & Sons Ltd.

  12. High-temperature diode laser pumps for directed energy fiber lasers (Conference Presentation)

    Science.gov (United States)

    Kanskar, Manoj; Bao, Ling; Chen, Zhigang; DeVito, Mark; Dong, Weimin; Grimshaw, Mike P.; Guan, Xinguo; Hemenway, David M.; Martinsen, Robert; Zhang, Jim; Zhang, Shiguo

    2017-05-01

    Kilowatt-class fiber lasers and amplifiers are becoming increasingly important building blocks for power-scaling laser systems in various different architectures for directed energy applications. Currently, state-of-the-art Yb-doped fiber lasers operating near 1060 nm operate with optical-to-optical power-conversion efficiency of about 66%. State-of-the-art fiber-coupled pump diodes near 975 nm operate with about 50% electrical-to-fiber-coupled optical power conversion efficiency at 25C heatsink temperature. Therefore, the total system electrical-to-optical power conversion efficiency is about 33%. As a result, a 50-kW fiber laser will generate 75 kW of heat at the pump module and 25 kW at the fiber laser module with a total waste heat of 100 kW. It is evident that three times as much waste heat is generated at the pump module. While improving the efficiency of the diodes primarily reduces the input power requirement, increasing the operating temperature primarily reduces the size and weight for thermal management systems. We will discuss improvement in diode laser design, thermal resistance of the package as well as improvement in fiber-coupled optical-to-optical efficiency to achieve high efficiency at higher operating temperature. All of these factors have a far-reaching implication in terms of significantly improving the overall SWAP requirements thus enabling DEW-class fiber lasers on airborne and other platforms.

  13. Facile and one-pot synthesis of uniform PtRu nanoparticles on polydopamine-modified multiwalled carbon nanotubes for direct methanol fuel cell application.

    Science.gov (United States)

    Chen, Fengxia; Ren, Junkai; He, Qian; Liu, Jun; Song, Rui

    2017-07-01

    A facile, environment-friendly and one-pot synthesis method for the preparation of high performance PtRu electrocatalysts on the multiwalled carbon nanotubes (MWCNTs) is reported. Herein, bimetallic PtRu electrocatalysts are deposited onto polydopamine (Pdop) - functionalized MWCNTs by mildly stirring at room temperature. Without the use of expensive chemicals or corrosive acids, this noncovalent functionalization of MWCNTs by Pdop is simple, facile and eco-friendly, and thus preserving the integrity and electronic structure of MWCNTs. Due to the well improved dispersion and the decreased size of alloy nanoparticles, the PtRu electrocatalysts on Pdop-functionalized MWCNTs show much better dispersion, higher electrochemically active surface area, and higher electrocatalytic activity for the electrooxidation of methanol in direct methanol fuel cells, compared with the conventional acid-treated MWCNTs. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Novel Integration Approach for In situ Monitoring of Temperature in Micro-direct Methanol Fuel Cell

    Science.gov (United States)

    Lee, Chi-Yuan; Huang, Ren-De; Chuang, Chih-Wei

    2007-10-01

    In this work, a porous silicon layer is fabricated as the gas diffusion layer (GDL) of a micro-direct methanol fuel cell (μDMFC) using micro-electro-mechanical-systems (MEMS) technology. Platinum is deposited on surface of the porous silicon layer to improve the electrical conductivity of the μDMFC. Physical vapor deposition (PVD) was utilized to deposit Pt metal and wet etching was adopted to form the conductive layer and micro-thermal sensors. The Pt acted both as a current collector and a micro-thermal sensor. We fabricated a resistance temperature detector (RTD) sensor for integration with the gas diffusion layer on the bipolar plate to measure the temperature inside the μDMFC. GDLs with pores of various sizes (10, 30, and 50 μm) were considered to test the performance of the μDMFC. A silicon wafer (500 μm) was etched using KOH wet etching to yield fuel channels with a depth of 450 μm and a width of 200 μm. Then, a porous silicon layer was formed by deep reactive ion etching (DRIE) to act as the GDL of the μDMFC. The experimental results obtained at various fuel flow rates, pore sizes and other operating conditions demonstrate that the maximum power density of the μDMFC is 1.784 mW/cm2, which was reached at 203 mV with 50-μm-diameter holes. The microsensor temperature was determined to be in the range from 20 to 46 °C and the resistance of the microsensor was in the range from 7.524 to 7.677 kΩ. Experimental results demonstrate that temperature is almost linearly related to resistance and that accuracy and sensitivity are 0.3 °C and 7.82× 10-4/°C, respectively.

  15. Synthesis of high quality monolayer graphene at reduced temperature on hydrogen-enriched evaporated copper (111) films.

    Science.gov (United States)

    Tao, Li; Lee, Jongho; Chou, Harry; Holt, Milo; Ruoff, Rodney S; Akinwande, Deji

    2012-03-27

    We report new findings on the chemical vapor deposition (CVD) of monolayer graphene with negligible defects (≥95% negligible defect-peak over 200 μm × 200 μm areas) on evaporated copper films. Compared to copper foils used in the CVD of graphene, several new unexpected results have been observed including high-quality monolayer synthesis at temperatures graphene grains on underlying copper grains. These thermal, chemical, and physical growth characteristics of graphene on copper films can be attributed to the distinct differences in the dominant crystal orientation of copper films (111) versus foils (100), and consequent dissimilar interplay with the precursor gas. This study suggests that reduced temperature, hydrogen-free synthesis of defect-negligible monolayer graphene is feasible, with the potential to shape and scale graphene grains by controlling the size and crystal orientation of the underlying copper grains. © 2012 American Chemical Society

  16. Room temperature synthesis of Ni-based alloy nanoparticles by radiolysis.

    Energy Technology Data Exchange (ETDEWEB)

    Nenoff, Tina Maria; Berry, Donald T.; Lu, Ping; Leung, Kevin; Provencio, Paula Polyak; Stumpf, Roland Rudolph; Huang, Jian Yu; Zhang, Zhenyuan

    2009-09-01

    Room temperature radiolysis, density functional theory, and various nanoscale characterization methods were used to synthesize and fully describe Ni-based alloy nanoparticles (NPs) that were synthesized at room temperature. These complementary methods provide a strong basis in understanding and describing metastable phase regimes of alloy NPs whose reaction formation is determined by kinetic rather than thermodynamic reaction processes. Four series of NPs, (Ag-Ni, Pd-Ni, Co-Ni, and W-Ni) were analyzed and characterized by a variety of methods, including UV-vis, TEM/HRTEM, HAADF-STEM and EFTEM mapping. In the first focus of research, AgNi and PdNi were studied. Different ratios of Ag{sub x}- Ni{sub 1-x} alloy NPs and Pd{sub 0.5}- Ni{sub 0.5} alloy NP were prepared using a high dose rate from gamma irradiation. Images from high-angle annular dark-field (HAADF) show that the Ag-Ni NPs are not core-shell structure but are homogeneous alloys in composition. Energy filtered transmission electron microscopy (EFTEM) maps show the homogeneity of the metals in each alloy NP. Of particular interest are the normally immiscible Ag-Ni NPs. All evidence confirmed that homogeneous Ag-Ni and Pd-Ni alloy NPs presented here were successfully synthesized by high dose rate radiolytic methodology. A mechanism is provided to explain the homogeneous formation of the alloy NPs. Furthermore, studies of Pd-Ni NPs by in situ TEM (with heated stage) shows the ability to sinter these NPs at temperatures below 800 C. In the second set of work, CoNi and WNi superalloy NPs were attempted at 50/50 concentration ratios using high dose rates from gamma irradiation. Preliminary results on synthesis and characterization have been completed and are presented. As with the earlier alloy NPs, no evidence of core-shell NP formation occurs. Microscopy results seem to indicate alloying occurred with the CoNi alloys. However, there appears to be incomplete reduction of the Na{sub 2}WO{sub 4} to form the W

  17. Molten salt-directed synthesis method for LiMn2O4 nanorods as a cathode material for a lithium-ion battery with superior cyclability

    CSIR Research Space (South Africa)

    Kebede, Mesfin A

    2017-02-01

    Full Text Available A molten salt synthesis technique has been used to prepare nanorods of Mn2O3 and single-crystal LiMn2O4 nanorods cathode material with superior capacity retention. The molten salt-directed synthesis involved the use of NaCl as the eutectic melt...

  18. Effects of vernal equinox solar eclipse on temperature and wind direction in Switzerland

    Science.gov (United States)

    Eugster, Werner; Emmel, Carmen; Wolf, Sebastian; Buchmann, Nina; McFadden, Joseph P.; Whiteman, Charles David

    2017-12-01

    The vernal equinox total solar eclipse of 20 March 2015 produced a maximum occultation of 65.8-70.1 % over Switzerland during the morning hours (09:22 to 11:48 CET). Skies were generally clear over the Swiss Alps due to a persistent high-pressure band between the UK and Russia associated with a rather weak pressure gradient over the continent. To assess the effects of penumbral shading on near-surface meteorology across Switzerland, air temperature data measured at 10 min intervals at 184 MeteoSwiss weather stations were used. Wind speed and direction data were available from 165 of these stations. Additionally, six Swiss FluxNet eddy covariance flux (ECF) sites provided turbulent measurements at 20 Hz resolution. During maximum occultation, the temperature drop was up to 5.8 K at a mountain site where cold air can pool in a topographic depression. The bootstrapped average of the maximum temperature drops of all 184 MeteoSwiss sites during the solar eclipse was 1.51 ± 0.02 K (mean ± SE). A detailed comparison with literature values since 1834 showed a temperature decrease of 2.6 ± 1.7 K (average of all reports), with extreme values up to 11 K. On fair weather days under weak larger-scale pressure gradients, local thermo-topographic wind systems develop that are driven by small-scale pressure and temperature gradients. At one ECF site, the penumbral shading delayed the morning transition from down-valley to up-valley wind conditions. At another site, it prevented this transition from occurring at all. Data from the 165 MeteoSwiss sites measuring wind direction did not show a consistent pattern of wind direction response to the passing of the penumbral shadow. These results suggest that the local topographic setting had an important influence on the temperature drop and the wind flow patterns during the eclipse. A significant cyclonic effect of the passing penumbral shadow was found in the elevation range ≈ 1700-2700 m a. s. l., but not at lower

  19. Effects of vernal equinox solar eclipse on temperature and wind direction in Switzerland

    Directory of Open Access Journals (Sweden)

    W. Eugster

    2017-12-01

    Full Text Available The vernal equinox total solar eclipse of 20 March 2015 produced a maximum occultation of 65.8–70.1 % over Switzerland during the morning hours (09:22 to 11:48 CET. Skies were generally clear over the Swiss Alps due to a persistent high-pressure band between the UK and Russia associated with a rather weak pressure gradient over the continent. To assess the effects of penumbral shading on near-surface meteorology across Switzerland, air temperature data measured at 10 min intervals at 184 MeteoSwiss weather stations were used. Wind speed and direction data were available from 165 of these stations. Additionally, six Swiss FluxNet eddy covariance flux (ECF sites provided turbulent measurements at 20 Hz resolution. During maximum occultation, the temperature drop was up to 5.8 K at a mountain site where cold air can pool in a topographic depression. The bootstrapped average of the maximum temperature drops of all 184 MeteoSwiss sites during the solar eclipse was 1.51 ± 0.02 K (mean ± SE. A detailed comparison with literature values since 1834 showed a temperature decrease of 2.6 ± 1.7 K (average of all reports, with extreme values up to 11 K. On fair weather days under weak larger-scale pressure gradients, local thermo-topographic wind systems develop that are driven by small-scale pressure and temperature gradients. At one ECF site, the penumbral shading delayed the morning transition from down-valley to up-valley wind conditions. At another site, it prevented this transition from occurring at all. Data from the 165 MeteoSwiss sites measuring wind direction did not show a consistent pattern of wind direction response to the passing of the penumbral shadow. These results suggest that the local topographic setting had an important influence on the temperature drop and the wind flow patterns during the eclipse. A significant cyclonic effect of the passing penumbral shadow was found in the elevation range

  20. Low temperature synthesis of layered NaxCoO2 and KxCoO2 from ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. We report a low temperature synthesis of layered Na0⋅20CoO2 and. K0⋅44CoO2 phases from NaOH and KOH fluxes at 400°C. These layered oxides are employed to prepare hexagonal HCoO2, LixCoO2 and Delafossite AgCoO2 phases by ion exchange method. The resulting oxides were characterised by ...

  1. Low temperature synthesis of layered NaxCoO2 and KxCoO2 from ...

    Indian Academy of Sciences (India)

    We report a low temperature synthesis of layered Na0.20CoO2 and K0.44CoO2 phases from NaOH and KOH fluxes at 400°C. These layered oxides are employed to prepare hexagonal HCoO2, LiCoO2 and Delafossite AgCoO2 phases by ion exchange method. The resulting oxides were characterised by powder X-ray ...

  2. Quick high-temperature hydrothermal synthesis of mesoporous materials with 3D cubic structure for the adsorption of lysozyme.

    Science.gov (United States)

    Lawrence, Geoffrey; Baskar, Arun V; El-Newehy, Mohammed H; Cha, Wang Soo; Al-Deyab, Salem S; Vinu, Ajayan

    2015-04-01

    Three-dimensional cage-like mesoporous FDU-12 materials with large tuneable pore sizes ranging from 9.9 to 15.6 nm were prepared by varying the synthesis temperature from 100 to 200 °C for the aging time of just 2 h using a tri-block copolymer F-127(EO106PO70EO106) as the surfactant and 1,3,5-trimethyl benzene as the swelling agent in an acidic condition. The mesoporous structure and textural features of FDU-12-HX (where H denotes the hydrothermal method and X denotes the synthesis temperature) samples were elucidated and probed using x-ray diffraction, N2 adsorption, (29)Si magic angle spinning nuclear magnetic resonance, scanning electron microscopy and transmission electron microscopy. It has been demonstrated that the aging time can be significantly reduced from 72 to 2 h without affecting the structural order of the FDU-12 materials with a simple adjustment of the synthesis temperature from 100 to 200 °C. Among the materials prepared, the samples prepared at 200 °C had the highest pore volume and the largest pore diameter. Lysozyme adsorption experiments were conducted over FDU-12 samples prepared at different temperatures in order to understand their biomolecule adsorption capacity, where the FDU-12-HX samples displayed high adsorption performance of 29 μmol g(-1) in spite of shortening the actual synthesis time from 72 to 2 h. Further, the influence of surface area, pore volume and pore diameter on the adsorption capacity of FDU-12-HX samples has been investigated and results are discussed in correlation with the textural parameters of the FDU-12-HX and other mesoporous adsorbents including SBA-15, MCM-41, KIT-5, KIT-6 and CMK-3.

  3. Direct Synthesis of Carbon Nanotubes at Low Temperature by the Reaction of CCl4 and Ferrocene

    Science.gov (United States)

    Luo, Wei; Tang, Yan; He, Mingsheng; Ouyang, Degang; Ding, Cuijiao; Han, Bin; Zhu, Shanhe; Li, Minghui

    Islands-like amorphous carbon nanotubes (a-CNTs) and multi-wall carbon nanotubes (MWCNTs) have been synthesized by the reaction of CCl4 and ferrocene without or with Co/N alloy as growth catalyst at 160 and 350 ºC, respectively. The as-obtained products are characterized by FESEM, TEM, HRTEM, Raman spectroscopy, and nitrogen adsorption-desorption analysis. The results show that a-CNTs have an outer diameter around 450 nm and a length of up to 5 μm, whereas MWCNTs are 20 nm in diameter and 1.5 μm in length. The specific surface area of a-CNTs and MWCNTs are determined to be 1092 and 364 m2×g-1, respectively. Dichlorocarbene and cyclopentadienyl groups are proved to be the reaction intermediates by GC-MS measurements. A possible growth mechanism of the a-CNTs and MWCNTs has been proposed.

  4. Kinetic effects in the photomediated synthesis of silver nanodecahedra and nanoprisms: combined effect of wavelength and temperature.

    Science.gov (United States)

    Wang, Haitao; Cui, Xiaoqiang; Guan, Weiming; Zheng, Xianliang; Zhao, Hetong; Wang, Zhao; Wang, Qiyu; Xue, Tianyu; Liu, Chang; Singh, David J; Zheng, Weitao

    2014-07-07

    Photomediated synthesis is a reliable, high yield method for the production of a variety of morphologies of silver nanoparticles. Here, we report synthesis of silver nanoprisms and nanodecahedra with tunable sizes via control of the reaction temperature and the irradiation wavelength. The results show that shorter excitation wavelengths and lower reaction temperatures result in high yields of nanodecahedra, while longer excitation wavelengths and higher reaction temperatures result in the formation of nanoprisms. The mechanism for the growth condition dependent evolution in the morphology of the silver particles is discussed as a kinetically controlled process. This is based on analysis of the reaction kinetics at various excitation wavelengths and temperatures. The energy barrier for the transformation from seeds to nanodecahedra is relatively high and requires a shorter wavelength. Thus longer wavelength illumination leads to the formation of nanoprisms. Thermodynamically stable five-fold twinning structures are shown to evolve from twin plane structures. The fast reaction rate at higher temperature favors the growth of nanoprisms by preferential Ag deposition on planar structures in a kinetics-controlled mode, while slower rates yield thermodynamically favored nanodecahedra.

  5. Synthesis of zeolite from Italian coal fly ash: differences in crystallization temperature using seawater instead of distilled water.

    Science.gov (United States)

    Belviso, Claudia; Cavalcante, Francesco; Fiore, Saverio

    2010-05-01

    In this study Italian coal fly ash was converted into several types of zeolite in laboratory experiments with temperatures of crystallization ranging from 35 up to 90 degrees C. Distilled and seawater were used during the hydrothermal synthesis process in separate experiments, after a pre-treatment fusion with NaOH. The results indicate that zeolites could be formed from different kind of Italian coal fly ash at low temperature of crystallization using both distilled and seawater. SEM data and the powder patterns of X-ray diffraction analysis show that faujasite, zeolite ZK-5 and sodalite were synthesized when using both distilled and seawater; zeolite A crystallized only using distilled water. In particular the experiments indicate that the synthesis of zeolite X and zeolite ZK-5 takes place at lower temperatures when using seawater (35 and 45 degrees C, respectively). The formation of sodalite is always competitive with zeolite X which shows a metastable behaviour at higher temperatures (70-90 degrees C). The chemical composition of the fly ash source could be responsible of the differences on the starting time of synthesized zeolite with distilled water, in any case our data show that the formation of specific zeolites takes place always at lower temperatures when using seawater. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  6. Directional gravity wave momentum fluxes in the stratosphere derived from high-resolution AIRS temperature data

    Science.gov (United States)

    Ern, M.; Hoffmann, L.; Preusse, P.

    2017-01-01

    In order to reduce uncertainties in modeling the stratospheric circulation, global observations of gravity wave momentum flux (GWMF) vectors are required for comparison with distributions of resolved and parametrized GWMF in global models. For the first time, we derive GWMF vectors globally from data of a nadir-viewing satellite instrument: we apply a 3-D method to an Atmospheric Infrared Sounder (AIRS) temperature data set that was optimized for gravity wave (GW) analysis. For January 2009, the resulting distributions of GW amplitudes and of net GWMF highlight the importance of GWs in the polar vortex and the summertime subtropics. Net GWMF is preferentially directed opposite to the background wind, and, interestingly, it is dominated by large-amplitude GWs of relatively long horizontal wavelength. For convective GW sources, these large horizontal scales are in contradiction with traditional thoughts. However, the observational filter effect needs to be kept in mind when interpreting the results.

  7. Correction: An unsymmetrical non-fullerene acceptor: synthesis via direct heteroarylation, self-assembly, and utility as a low energy absorber in organic photovoltaic cells.

    Science.gov (United States)

    Payne, Abby-Jo; Li, Shi; Dayneko, Sergey V; Risko, Chad; Welch, Gregory C

    2017-09-21

    Correction for 'An unsymmetrical non-fullerene acceptor: synthesis via direct heteroarylation, self-assembly, and utility as a low energy absorber in organic photovoltaic cells' by Abby-Jo Payne et al., Chem. Commun., 2017, 53, 10168-10171.

  8. Influence of Synthesis Temperature on the Growth and Surface Morphology of Co3O4 Nanocubes for Supercapacitor Applications

    Science.gov (United States)

    Samal, Rashmirekha; Dash, Barsha; Sarangi, Chinmaya Kumar; Subbaiah, Tondepu; Senanayake, Gamini; Minakshi, Manickam

    2017-01-01

    A facile hydrothermal route to control the crystal growth on the synthesis of Co3O4 nanostructures with cube-like morphologies has been reported and tested its suitability for supercapacitor applications. The chemical composition and morphologies of the as-prepared Co3O4 nanoparticles were extensively characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Varying the temperature caused considerable changes in the morphology, the electrochemical performance increased with rising temperature, and the redox reactions become more reversible. The results showed that the Co3O4 synthesized at a higher temperature (180 °C) demonstrated a high specific capacitance of 833 F/g. This is attributed to the optimal temperature and the controlled growth of nanocubes. PMID:29088061

  9. Synthesis of thick diamond films by direct current hot-cathode plasma chemical vapour deposition

    CERN Document Server

    Jin Zeng Sun; Bai Yi Zhen; Lu Xian Yi

    2002-01-01

    The method of direct current hot-cathode plasma chemical vapour deposition has been established. A long-time stable glow discharge at large discharge current and high gas pressure has been achieved by using a hot cathode in the temperature range from 1100 degree C to 1500 degree C and non-symmetrical configuration of the poles, in which the diameter of the cathode is larger than that of anode. High-quality thick diamond films, with a diameter of 40-50 mm and thickness of 0.5-4.2 mm, have been synthesized by this method. Transparent thick diamond films were grown over a range of growth rates between 5-10 mu m/h. Most of the thick diamond films have thermal conductivities of 10-12 W/K centre dot cm. The thick diamond films with high thermal conductivity can be used as a heat sink of semiconducting laser diode array and as a heat spreading and isolation substrate of multichip modules. The performance can be obviously improved

  10. Direct synthesis of magnetite nanoparticles from iron(II) carboxymethylcellulose and their performance as NMR contrast agents

    Energy Technology Data Exchange (ETDEWEB)

    Gomes da Silva, Delmarcio; Hiroshi Toma, Sergio; Menegatti de Melo, Fernando [Instituto de Química, Universidade de São Paulo, São Paulo, SP (Brazil); Carvalho, Larissa Vieira C.; Magalhães, Alvicler; Sabadini, Edvaldo [Instituto de Química, Universidade Estadual de Campinas – UNICAMP, Campinas, SP (Brazil); Domingues dos Santos, Antônio [Instituto de Física, Universidade de São Paulo, São Paulo, SP (Brazil); Araki, Koiti [Instituto de Química, Universidade de São Paulo, São Paulo, SP (Brazil); Toma, Henrique E., E-mail: henetoma@iq.usp.br [Instituto de Química, Universidade de São Paulo, São Paulo, SP (Brazil)

    2016-01-01

    Iron(II) carboxymethylcellulose (CMC) has been successfully employed in the synthesis of hydrophylic magnetite nanoparticles stabilized with a biopolymer coating, aiming applications in NMR imaging. The new method encompasses a convenient one-step synthetic procedure, allowing a good size control and yielding particles of about 10 nm (core size). In addition to the biocompatibility, the nanoparticles have promoted a drastic reduction in the transverse relaxation time (T{sub 2}) of the water protons. The relaxivity rates have been investigated as a function of the nanoparticles concentration, showing a better performance in relation to the common NMR contrast agents available in the market. - Highlights: • Stable, hydrophylic magnetic nanoparticles have been obtained. • Direct use of iron(II) carboxymethylcellulose improves the synthesis. • The magnetic nanoparticles exhibit high spin–spin relaxivity. • The particles promote dark contrast by decreasing the T{sub 2} relaxation time.

  11. Combustion synthesis of molybdenum silicides and borosilicides for ultrahigh-temperature structural applications

    Science.gov (United States)

    Alam, Mohammad Shafiul

    Molybdenum silicides and borosilicides are promising structural materials for gas-turbine power plants. A major challenge, however, is to simultaneously achieve high oxidation resistance and acceptable mechanical properties at high temperatures. For example, molybdenum disilicide (MoSi2) has excellent oxidation resistance and poor mechanical properties, while Mo-rich silicides such as Mo5Si3 (called T 1) have much better mechanical properties but poor oxidation resistance. One approach is based on the fabrication of MoSi2-T 1 composites that combine high oxidation resistance of MoSi2 and good mechanical properties of T1. Another approach involves the addition of boron to Mo-rich silicides for improving their oxidation resistance through the formation of a borosilicate surface layer. In particular, Mo 5SiB2 (called T2) phase is considered as an attractive material. In the thesis, MoSi2-T1 composites and materials based on T2 phase are obtained by mechanically activated SHS. Use of SHS compaction (quasi-isostatic pressing) significantly improves oxidation resistance of the obtained MoSi2-T1 composites. Combustion of Mo-Si-B mixtures for the formation of T2 phase becomes possible if the composition is designed for the addition of more exothermic reactions leading to the formation of molybdenum boride. These mixtures exhibit spin combustion, the characteristics of which are in good agreement with the spin combustion theory. Oxidation resistance of the obtained Mo-Si-B materials is independent on the concentration of Mo phase in the products so that the materials with a higher Mo content are preferable because of better mechanical properties. Also, T2 phase has been obtained by the chemical oven combustion synthesis technique.

  12. Explosive Evaporating Phenomena of Cryogenic Fluids by Direct Contacting Normal Temperature Fluids

    Directory of Open Access Journals (Sweden)

    T Watanabe

    2016-09-01

    Full Text Available Cryogenic fluids have characteristics such as thermal stratification and flashing by pressure release in storage vessel. The mixture of the extreme low temperature fluid and the normal temperature fluid becomes the cause which causes pressure vessel and piping system crush due to explosive boiling and rapid freezing. In recent years in Japan, the demand of cryogenic fluids like a LH2, LNG is increasing because of the advance of fuel cell device technology, hydrogen of engine, and stream of consciousness for environmental agreement. These fuel liquids are cryogenic fluids. On the other hand, as for fisheries as well, the use of a source of energy that environment load is small has been being a pressing need. And, the need of the ice is high, as before, for keeping freshness of marine products in fisheries. Therefore, we carried out the experiments related to promotion of evaporating cryogenic fluids and generation of ice, in the contact directly of the water and liquid nitrogen. From the results of visualization, phenomena of explosive evaporating and ice forming were observed by using video camera.

  13. Direct temperature mass spectrometric study on the depth-dependent compositional gradients of aged triterpenoid varnishes

    Science.gov (United States)

    Theodorakopoulos, Charis; Boon, Jaap J.; Zafiropulos, Vassilis

    2009-07-01

    The depth profiles of aged dammar and mastic films, which were uncovered by optimized KrF excimer laser ablation (248 nm, 25 ns), were examined by direct temperature-resolved mass spectrometry (DTMS). The results establish the generation of depth-dependent compositional gradients in triterpenoid resins as a consequence of aging, for the first time on the molecular level. Electron ionization DTMS total ion currents show that the required temperature to volatilize the polar compounds and the relative amount of pyrolysis products of the high molecular weight condensed fraction is reduced when the upper layer of varying thickness of the films had been removed by the laser. The relative abundance of characteristic ion fragments of known oxidized triterpenoid compounds gradually decreased with depth. In contrast, the ion fragments of original resin molecules became more abundant with depth. The mass spectra of the bulk of the films resembled that of the control samples, which were not subjected to aging. Multivariant factor discriminant analysis quantified the oxidative gradients and showed that a depth of 15 [mu]m from the surface of the aged films is the threshold between highly and much less deteriorated material.

  14. Effect of Temperature Gradient Direction in the Catalyst Nanoparticle on CNTs Growth Mode

    Directory of Open Access Journals (Sweden)

    Liu Shang-Bin

    2010-01-01

    Full Text Available Abstract To improve the understanding on CNT growth modes, the various processes, including thermal CVD, MP-CVD and ECR-CVD, have been used to deposit CNTs on nanoporous SBA-15 and Si wafer substrates with C2H2 and H2 as reaction gases. The experiments to vary process parameter of ΔT, defined as the vector quantities of temperature at catalyst top minus it at catalyst bottom, were carried out to demonstrate its effect on the CNT growth mode. The TEM and TGA analyses were used to characterize their growth modes and carbon yields of the processes. The results show that ΔT can be used to monitor the temperature gradient direction across the catalyst nanoparticle during the growth stage of CNTs. The results also indicate that the tip-growth CNTs, base-growth CNTs and onion-like carbon are generally fabricated under conditions of ΔT > 0, <0 and ~0, respectively. Our proposed growth mechanisms can be successfully adopted to explain why the base- and tip-growth CNTs are common in thermal CVD and plasma-enhanced CVD processes, respectively. Furthermore, our experiments have also successfully demonstrated the possibility to vary ΔT to obtain the desired growth mode of CNTs by thermal or plasma-enhanced CVD systems for different applications.

  15. Direct determination of the enthalpy of formation of MoB in synthesis from simple substances in an SHS system

    Science.gov (United States)

    Lavut, E. G.; Chelovskaya, N. V.; Kashireninov, O. E.

    1993-10-01

    In a calorimetric bomb equipped with an electric microfurnace for heating a sample, self-propagating high-temperature synthesis (SHS) of molybdenum boride is realized in accordance with the reaction Mo (c) +B (amorph.)=MoB (c); the enthalpy of this reaction is measured, and the standard enthalpy of formation of molybdenum boride from metal molybdenum and crystaline boron is calculated: Δf H 0 (MoB,c,δ,β)=103.9α1.2kJ/mole.

  16. Methods for the synthesis of polyhydroxylated piperidines by diastereoselective dihydroxylation: Exploitation in the two-directional synthesis of aza-C-linked disaccharide derivatives

    Directory of Open Access Journals (Sweden)

    Nelson Adam

    2005-08-01

    Full Text Available Abstract Background: Many polyhydroxylated piperidines are inhibitors of the oligosaccharide processing enzymes, glycosidases and glycosyltransferases. Aza-C-linked disaccharide mimetics are compounds in which saturated polyhydroxylated nitrogen and oxygen heterocycles are linked by an all-carbon tether. The saturated oxygen heterocycle has the potential to mimic the departing sugar in a glycosidase-catalysed reaction and aza-C-linked disaccharide mimetics may, therefore, be more potent inhibitors of these enzymes. Results: The scope, limitations and diastereoselectivity of the dihydroxylation of stereoisomeric 2-butyl-1-(toluene-4-sulfonyl-1,2,3,6-tetrahydro-pyridin-3-ols is discussed. In the absence of a 6-substituent on the piperidine ring, the Upjohn (cat. OsO4, NMO, acetone-water and Donohoe (OsO4, TMEDA, CH2Cl2 conditions allow complementary diastereoselective functionalisation of the alkene of the (2R*,3R* diastereoisomer. However, in the presence of a 6-substituent, the reaction is largely controlled by steric effects with both reagents. The most synthetically useful protocols were exploited in the two-directional synthesis of aza-C-linked disaccharide analogues. A two-directional oxidative ring expansion was used to prepare bis-enones such as (2R,6S,2'S-6-methoxy-2-(6-methoxy-3-oxo-3,6-dihydro-2H-pyran-2-ylmethyl-1-(toluene-4-sulfonyl-1,6-dihydro-2H-pyridin-3-one from the corresponding difuran. Selective substitution of its N,O acetal was possible. The stereochemical outcome of a two-directional Luche reduction step was different in the two heterocyclic rings, and depended on the conformation of the ring. Finally, two-directional diastereoselective dihydroxylation yielded seven different aza-C-linked disaccharide analogues. Conclusion: A two-directional approach may be exploited in the synthesis of aza-C-linked disaccharide mimetics. Unlike previous approaches to similar molecules, neither of the heterocyclic rings is directly derived

  17. Differences in Rate and Direction of Shifts between Phytoplankton Size Structure and Sea Surface Temperature

    Directory of Open Access Journals (Sweden)

    Hisatomo Waga

    2017-03-01

    Full Text Available Species distributions are changing with various rates and directions in response to recent global warming. The velocity of sea surface temperature (SST has been used to predict species migration and persistence as an expectation of how species track their thermal niches; however, several studies have found that evidence for species shifts has deviated from the velocity of SST. This study investigated whether estimation of the velocity of shifts in phytoplankton size structure using remote sensing data could contribute to better prediction of species shifts. A chlorophyll-a (Chla size distribution (CSD model was developed by quantifying the relationships between the size structure of the phytoplankton community and the spectral features of the phytoplankton absorption coefficient (aph(λ, based on the principal component analysis approach. Model validation demonstrated that the exponent of CSD (hereafter, CSD slope, which can describe the synoptic size structure of a phytoplankton community, was derived successfully with a relative root mean square error of 18.5%. The median velocity of CSD slope across the ocean was 485.2 km·decade−1, broadly similar to Chla (531.5 km·decade−1. These values were twice the velocity of SST, and the directions of shifts in CSD slope and Chla were quite different from that of SST. Because Chla is generally covariant with the size structure of a phytoplankton community, we believe that spatiotemporal changes in Chla can explain the variations of phytoplankton size structure. Obvious differences in both rate and direction of shifts were found between the phytoplankton size structure and SST, implying that shifts of phytoplankton size structure could be a powerful tool for assessing the distributional shifts of marine species. Our results will contribute to generate global and regional maps of expected species shifts in response to environmental forcing.

  18. Retrieval of canopy component temperatures through Bayesian inversion of directional thermal measurements

    NARCIS (Netherlands)

    Timmermans, J.; Verhoef, W.; Tol, van der C.; Su, Z.

    2009-01-01

    Evapotranspiration is usually estimated in remote sensing from single temperature value representing both soil and vegetation. This surface temperature is an aggregate over multiple canopy components. The temperature of the individual components can differ significantly, introducing errors in the

  19. High temperature high velocity direct power extraction using an open-cycle oxy-combustion system

    Energy Technology Data Exchange (ETDEWEB)

    Love, Norman [Univ. of Texas, El Paso, TX (United States)

    2017-09-29

    The implementation of oxy-fuel technology in fossil-fuel power plants may contribute to increased system efficiencies and a reduction of pollutant emissions. One technology that has potential to utilize the temperature of undiluted oxy-combustion flames is open-cycle magnetohydrodynamic (MHD) power generators. These systems can be configured as a topping cycle and provide high enthalpy, electrically conductive flows for direct conversion of electricity. This report presents the design and modeling strategies of a MHD combustor operating at temperatures exceeding 3000 K. Throughout the study, computational fluid dynamics (CFD) models were extensively used as a design and optimization tool. A lab-scale 60 kWth model was designed, manufactured and tested as part of this project. A fully-coupled numerical method was developed in ANSYS FLUENT to characterize the heat transfer in the system. This study revealed that nozzle heat transfer may be predicted through a 40% reduction of the semi-empirical Bartz correlation. Experimental results showed good agreement with the numerical evaluation, with the combustor exhibiting a favorable performance when tested during extended time periods. A transient numerical method was employed to analyze fuel injector geometries for the 60-kW combustor. The ANSYS FLUENT study revealed that counter-swirl inlets achieve a uniform pressure and velocity ratio when the ports of the injector length to diameter ratio (L/D) is 4. An angle of 115 degrees was found to increase distribution efficiency. The findings show that this oxy-combustion concept is capable of providing a high-enthalpy environment for seeding, in order to render the flow to be conductive. Based on previous findings, temperatures in the range of 2800-3000 K may enable magnetohydrodynamic power extraction. The heat loss fraction in this oxy-combustion system, based on CFD and analytical calculations, at optimal operating conditions, was estimated to be less than 10 percent

  20. Efficient Conversion of Lignin to Electricity Using a Novel Direct Biomass Fuel Cell Mediated by Polyoxomethalates at Low Temperatures

    Science.gov (United States)

    Xuebing Zhao; Junyong Zhu

    2016-01-01

    A novel polyoxometalates (POMs) mediated direct biomass fuelcelI (DBFC) was used in this study to directly convert lignin to electricity at low temperatures with high power output and Faradaic efficiency. When phosphomolybdic acid H3PMo12O40 (PMo12) was used as the electron and...

  1. Highly Efficient One-Pot Synthesis of 2,4-Disubstituted Thiazoles Using Au(I Catalyzed Oxidation System at Room Temperature

    Directory of Open Access Journals (Sweden)

    Gongde Wu

    2016-08-01

    Full Text Available In the present work, gold complex catalysts with Mor-DalPhos ligands were successfully prepared using mesylates as counter ions. Seven ammonium sulfonates were synthesized to promote the production of intermediate sulfonyloxymethyl ketone. It was found that low-acidity N,N-dimethylbenzenaminium methanesulfonate showed excellent activity in the reaction. Furthermore, the catalysts effectively avoided the loss of activity due to the low acidity. Various thioamides were directly added to the resulting reaction mixture without the separation of intermediate product. Then, twenty kinds of 2,4-disubstituted thiazoles were efficiently synthesized at room temperature with the highest yield of 91%. This work provides an efficiency and mild gold-catalyzed oxidation system for the one-pot synthesis of thiazole and its derivatives.

  2. Direct control of the temperature rise in parallel transmission by means of temperature virtual observation points: Simulations at 10.5 Tesla.

    Science.gov (United States)

    Boulant, Nicolas; Wu, Xiaoping; Adriany, Gregor; Schmitter, Sebastian; Uğurbil, Kamil; Van de Moortele, Pierre-François

    2016-01-01

    A method using parallel transmission to mitigate B1+ inhomogeneity while explicitly constraining the temperature rise is reported and compared with a more traditional SAR-constrained pulse design. Finite difference time domain simulations are performed on a numerical human head model and for a 16-channel coil at 10.5 Tesla. Based on a set of presimulations, a virtual observation point compression model for the temperature rise is derived. This compact representation is then used in a nonlinear programming algorithm for pulse design under explicit temperature rise constraints. In the example of a time-of-flight sequence, radiofrequency pulse performance in some cases is increased by a factor of two compared with SAR-constrained pulses, while temperature rise is directly and efficiently controlled. Pulse performance can be gained by relaxing the SAR constraints, but at the expense of a loss of direct control on temperature. Given the importance of accurate safety control at ultrahigh field and the lack of direct correspondence between SAR and temperature, this work motivates the need for thorough thermal studies in normal in vivo conditions. The tools presented here will possibly contribute to safer and more efficient MR exams. © 2015 Wiley Periodicals, Inc.

  3. MAP6-F is a temperature sensor that directly binds to and protects microtubules from cold-induced depolymerization.

    Science.gov (United States)

    Delphin, Christian; Bouvier, Denis; Seggio, Maxime; Couriol, Emilie; Saoudi, Yasmina; Denarier, Eric; Bosc, Christophe; Valiron, Odile; Bisbal, Mariano; Arnal, Isabelle; Andrieux, Annie

    2012-10-12

    Microtubules are dynamic structures that present the peculiar characteristic to be ice-cold labile in vitro. In vivo, microtubules are protected from ice-cold induced depolymerization by the widely expressed MAP6/STOP family of proteins. However, the mechanism by which MAP6 stabilizes microtubules at 4 °C has not been identified. Moreover, the microtubule cold sensitivity and therefore the needs for microtubule stabilization in the wide range of temperatures between 4 and 37 °C are unknown. This is of importance as body temperatures of animals can drop during hibernation or torpor covering a large range of temperatures. Here, we show that in the absence of MAP6, microtubules in cells below 20 °C rapidly depolymerize in a temperature-dependent manner whereas they are stabilized in the presence of MAP6. We further show that in cells, MAP6-F binding to and stabilization of microtubules is temperature- dependent and very dynamic, suggesting a direct effect of the temperature on the formation of microtubule/MAP6 complex. We also demonstrate using purified proteins that MAP6-F binds directly to microtubules through its Mc domain. This binding is temperature-dependent and coincides with progressive conformational changes of the Mc domain as revealed by circular dichroism. Thus, MAP6 might serve as a temperature sensor adapting its conformation according to the temperature to maintain the cellular microtubule network in organisms exposed to temperature decrease.

  4. Effect of temperature on the synthesis of silver nanoparticles with polyethylene glycol: new insights into the reduction mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Fleitas-Salazar, Noralvis; Silva-Campa, Erika; Pedroso-Santana, Seidy; Tanori, Judith; Pedroza-Montero, Martín R.; Riera, Raúl, E-mail: rriera@cifus.uson.mx [Universidad de Sonora (Mexico)

    2017-03-15

    Polyethylene glycol (PEG) molecules act as a reducing and stabilizing agent in the formation of silver nanoparticles. PEG undergoes thermal oxidative degradation at temperatures over 70 °C in the presence of oxygen. Here, we studied how the temperature and an oxidizing atmosphere could affect the synthesis of silver nanoparticles with PEG. We tested different AgNO{sub 3} concentrations for nanoparticles syntheses using PEG of low molecular weight, at 60 and 100 °C. At the higher temperature, the reducing action of PEG increased and the effect of PEG/Ag{sup +} ratio on nanoparticles aggregation changed. These results suggest that different synthesis mechanisms operate at 60 and 100 °C. Thus, at 60 °C the reduction of silver ions can occur through the oxidation of the hydroxyl groups of PEG, as has been previously reported. We propose that the thermal oxidative degradation of PEG at 100 °C increases the number of both, functional groups and molecules that can reduce silver ions and stabilize silver nanoparticles. This degradation process could explain the enhancement of PEG reducing action observed by other authors when they increase the reaction temperature or use a PEG of higher molecular weight.

  5. First synthesis of Cr{sub 3}C{sub 2} nanowhiskers by low-temperature vaccum carburization from precursor

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Yongzhong, E-mail: jyzcd@163.com [Department of Materials Science and Engineering, Sichuan University of Science and Engineering, Zigong City, 643000 (China); Zhang, Zhengquan [Department of Materials Science and Engineering, Sichuan University of Science and Engineering, Zigong City, 643000 (China); Ye, Faming [Department of Materials Science and Engineering, Sichuan University of Science and Engineering, Zigong City, 643000 (China); Deyang Haohua Qingping Linkuang Co. Ltd., Deyang City, 618000 (China); Liu, Dongliang; Chen, Jian; Yang, Ruisong [Department of Materials Science and Engineering, Sichuan University of Science and Engineering, Zigong City, 643000 (China)

    2016-08-15

    To assist a widespread application of chromium carbide (Cr{sub 3}C{sub 2}), it is important to synthesize Cr{sub 3}C{sub 2} nanowhiskers and but there are almost no related reports. In this letter, we first reported a low-lost synthesis of Cr{sub 3}C{sub 2} nanowhiskers at 800 °C by vacuum carburization process using precursor powders as raw materials without Fe/Co/Ni catalysts. X-ray diffraction (XRD) data confirm that Cr{sub 3}C{sub 2} nanowhiskers have a single-phase orthorhombic structure. A homogeneous chemical composition can be obtained in the calcining product from precursor, which reduces significantly the synthesis temperature. Morphological studies using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) show Cr{sub 3}C{sub 2} nanowhiskers have a clean and smooth surface with a diameter size of ∼50 nm. - Highlights: • Cr{sub 3}C{sub 2} nanowhiskers were first synthesized at 800 °C by a novel LVCP method. • A homogeneous chemical composition from precursor reduces synthesis temperature. • Cr{sub 3}C{sub 2} nanowhiskers have a single-phase structure and a diameter size of ∼50 nm.

  6. Direct synthesis of mesoporous carbon from the carbonization of hydroxypropyl- β-cyclodextrin/silica composite and its catalytic performance

    Science.gov (United States)

    Wang, Hui Chun; Li, Bao Lin; Li, Jiang Tao; Lin, Pei; Bian, Xiao Bing; Li, Jiang; Zhang, Bo; Wan, Zhuan Xin

    2011-02-01

    A simple and efficient route is reported for the synthesis of mesoporous carbon materials by directly carbonizing hydroxypropyl-β-cyclodextrin-silica composites. The resulting carbon materials, with uniform wormlike mesoporous structure and certain degree graphitic phase characteristics in porous wall, possess narrow pore size distribution, high surface area (>1000 m2 g-1) and pore volume (>1.2 cm3 g-1). It is worth mentioning that the carbon materials have high catalytic activity for the reduction of p-nitrotoluene using hydrazine hydrate as the reducing agent; moreover, the catalytic activity is not reduced notably after being reused for six times.

  7. Efficient synthesis and first regioselective C-3 direct arylation of imidazo[1,2-b]pyrazoles.

    Science.gov (United States)

    Grosse, Sandrine; Pillard, Christelle; Massip, Stéphane; Léger, Jean Michel; Jarry, Christian; Bourg, Stéphane; Bernard, Philippe; Guillaumet, Gérald

    2012-11-19

    Highly regioselective: An efficient synthesis of the imidazo[1,2-b]pyrazole core has been developed, and the first regioselective palladium-catalyzed direct arylation of the C-3 position is described (see scheme). Good to excellent yields were obtained for a wide range of aryl partners with electron-rich and electron-poor substituents. This methodology allows rapid access to a large variety of imidazo[1,2-b]pyrazole products and could open the way to the design of new biologically active compounds. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Combining two-directional synthesis and tandem reactions, part 11: second generation syntheses of (+/-)-hippodamine and (+/-)-epi-hippodamine.

    Science.gov (United States)

    Newton, Annabella F; Rejzek, Martin; Alcaraz, Marie-Lyne; Stockman, Robert A

    2008-01-17

    Hippodamine is a volatile defence alkaloid isolated from ladybird beetles which holds potential as an agrochemical agent and was the subject of a synthesis by our group in 2005. Two enhancements to our previous syntheses of (+/-)-hippodamine and (+/-)-epi-hippodamine are presented which are able to shorten the syntheses by up to two steps. Key advances include a two-directional homologation by cross metathesis and a new tandem reductive amination/double intramolecular Michael addition which generates 6 new bonds, 2 stereogenic centres and two rings, giving a single diastereomer in 74% yield.

  9. Merging Photoredox and Nickel Catalysis: The Direct Synthesis of Ketones by the Decarboxylative Arylation of α-Oxo Acids.

    Science.gov (United States)

    Chu, Lingling; Lipshultz, Jeffrey M; MacMillan, David W C

    2015-06-26

    The direct decarboxylative arylation of α-oxo acids has been achieved by synergistic visible-light-mediated photoredox and nickel catalysis. This method offers rapid entry to aryl and alkyl ketone architectures from simple α-oxo acid precursors via an acyl radical intermediate. Significant substrate scope is observed with respect to both the oxo acid and arene coupling partners. This mild decarboxylative arylation can also be utilized to efficiently access medicinal agents, as demonstrated by the rapid synthesis of fenofibrate. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Strain rate and temperature effects on crack initiation of direct aged 718 Alloy

    Directory of Open Access Journals (Sweden)

    Perrais Maxime

    2014-01-01

    Full Text Available During mechanical tests at high temperature in an oxidizing atmosphere, the effects of strain rate on crack initiation are noticeable. This effect is due to a coupling between local mechanical loading and oxidation. Samples were machined in a turbine disk made of direct aged alloy 718. Tests were performed to understand the effect of these couplings on crack initiation and to ensure lifetime is optimized. This study compared the cracking resistance of two different specimen geometries at a given plastic strain and performed quantitative measurement of the mechanical loading conditions inducing crack initiation between 600 ∘C and 650 ∘C. Sample geometries consisted in tensile flat specimens and V-shaped samples. This specific geometry was used to localize strain and damage in the apex of the V and to reach strain rates lower than those possible on standard specimens. Digital image correlation technique was used to provide strain measurements. For each temperature and strain rate, finite element calculations using the identified constitutive law were performed to get a refined level of strain in different areas at the V apex. Tests were stopped after an imposed displacement corresponding to a given plastic strain distribution. SEM observations of the surface of the flat tensile samples revealed no crack initiation. On the contrary, SEM observations at the apex of V specimens for which the level of cumulative strain was close to the level of cumulative strain of flat samples reveal the presence of intergranular damage when the strain rate used was below a given level.

  11. Can Aerosol Direct Radiative Effects Account for Analysis Increments of Temperature in the Tropical Atlantic?

    Science.gov (United States)

    da Silva, Arlindo M.; Alpert, Pinhas

    2016-01-01

    In the late 1990's, prior to the launch of the Terra satellite, atmospheric general circulation models (GCMs) did not include aerosol processes because aerosols were not properly monitored on a global scale and their spatial distributions were not known well enough for their incorporation in operational GCMs. At the time of the first GEOS Reanalysis (Schubert et al. 1993), long time series of analysis increments (the corrections to the atmospheric state by all available meteorological observations) became readily available, enabling detailed analysis of the GEOS-1 errors on a global scale. Such analysis revealed that temperature biases were particularly pronounced in the Tropical Atlantic region, with patterns depicting a remarkable similarity to dust plumes emanating from the African continent as evidenced by TOMS aerosol index maps. Yoram Kaufman was instrumental encouraging us to pursue this issue further, resulting in the study reported in Alpert et al. (1998) where we attempted to assess aerosol forcing by studying the errors of a the GEOS-1 GCM without aerosol physics within a data assimilation system. Based on this analysis, Alpert et al. (1998) put forward that dust aerosols are an important source of inaccuracies in numerical weather-prediction models in the Tropical Atlantic region, although a direct verification of this hypothesis was not possible back then. Nearly 20 years later, numerical prediction models have increased in resolution and complexity of physical parameterizations, including the representation of aerosols and their interactions with the circulation. Moreover, with the advent of NASA's EOS program and subsequent satellites, atmospheric aerosols are now monitored globally on a routine basis, and their assimilation in global models are becoming well established. In this talk we will reexamine the Alpert et al. (1998) hypothesis using the most recent version of the GEOS-5 Data Assimilation System with assimilation of aerosols. We will

  12. Template-directed synthesis of nets based upon octahemioctahedral cages that encapsulate catalytically active metalloporphyrins

    KAUST Repository

    Zhang, ZhenJie

    2012-01-18

    meso-Tetra(N-methyl-4-pyridyl)porphine tetratosylate (TMPyP) templates the synthesis of six new metal-organic materials by the reaction of benzene-1,3,5-tricarboxylate with transition metals, five of which exhibit HKUST-1 or tbo topology (M = Fe, Mn, Co, Ni, Mg). The resulting materials, porph@MOMs, selectively encapsulate the corresponding metalloporphyrins in octahemioctahedral cages and can serve as size-selective heterogeneous catalysts for oxidation of olefins. © 2011 American Chemical Society.

  13. Self-assembled peptide template directed synthesis of one-dimensional inorganic nanostructures and their applications

    OpenAIRE

    Acar, Handan

    2012-01-01

    Ankara : The Materials Science and Nanotechnology Program of the Graduate School of Engineering and Sciences of Bilkent University, 2012. Thesis (Ph. D.) -- Bilkent University, 2012. Includes bibliographical references. Engineering at the nano scale has been an active area of science and technology over the last decade. Inspired by nature, synthesis of functional inorganic materials using synthetic organic templates constitutes the theme of this thesis. Developing organic te...

  14. Direct Emissivity Measurements of Painted Metals for Improved Temperature Estimation During Laser Damage Testing

    Science.gov (United States)

    2014-03-27

    authors.) . . . . . . . . . . . . . . . . . . 19 4.1 Temperature-dependent spectral emissivity for black painted Al2024 -T3 alloy as temperature is...increased from room temperature to 500◦ C. . . . . . . . . . 23 4.2 Detail of the spectral emissivity profiles for black painted Al2024 -T3 alloy in the...profiles for light gray camouflage painted Al2024 -T3 alloy as temperature is increased from room temperature to 500◦ C. . . . . . . . . . 25 4.6

  15. Effect of Synthesis Temperature on the Growth Iron-Filled Carbon Nanotubes as Evidenced by Structural, Micro-Raman, and Thermogravimetric Analyses

    Directory of Open Access Journals (Sweden)

    M. S. Shamsudin

    2012-01-01

    Full Text Available Tubular structure and well dense of aligned carbon nanotubes (CNTs were formulated using two-stage catalytic chemical vapor deposition apparatus. In this experiment, aligned CNT was synthesized in the range of 700–900°C temperatures with increment rate of 50°C per sample. The aligned CNT properties were investigated via field emission scanning electron microscope, micro-Raman spectrometer and thermogravimetric analyzer. The experimental results showed that aligned CNT properties were highly dependent on synthesis temperature changes. The optimum temperature of higher crystallinity was observed at 800°C synthesis temperature. However, the highest yield of nanotubes (~99.99% was obtained at 900°C synthesis temperature. Aligned CNT orientation was in a parallel form and packed together in orderly manner. The behaviors of aligned CNT will be discussed in detail in this paper.

  16. Facial Sketch Synthesis Using Two-dimensional Direct Combined Model-based Face-Specific Markov Network.

    Science.gov (United States)

    Tu, Ching-Ting; Chan, Yu-Hsien; Chen, Yi-Chung

    2016-05-20

    A facial sketch synthesis system is proposed featuring a two-dimensional direct combined model (2DDCM)-based facespecific Markov network. In contrast to existing facial sketch synthesis systems, the proposed scheme aims to synthesize sketches which reproduce the unique drawing style of a particular artist, where this drawing style is learned from a dataset consisting of a large number of image/sketch pairwise training samples. The synthesis system comprises three modules, namely a global module, a local module, and an enhancement module. The global module applies a 2DDCM approach to synthesize the global facial geometry and texture of the input image. The detailed texture is then added to the synthesized sketch in a local patch-based manner using a parametric 2DDCM model and a non-parametric Markov random field (MRF) network. Notably, the MRF approach gives the synthesized results an appearance more consistent with the drawing style of the training samples, while the 2DDCM approach enables the synthesis of outcomes with a more derivative style. As a result, the similarity between the synthesized sketches and the input images is greatly improved. Finally, a post-processing operation is performed to enhance the shadowed regions of the synthesized image by adding strong lines or curves to emphasize the lighting conditions. The experimental results confirm that the synthesized facial images are in good qualitative and quantitative agreement with the input images as well as the ground-truth sketches provided by the same artist. The representing power of the proposed framework is demonstrated by synthesizing facial sketches from input images with a wide variety of facial poses, lighting conditions, and races even when such images are not included in the training dataset. Moreover, the practical applicability of the proposed framework is demonstrated by means of automatic facial recognition tests.

  17. Direct benefits and indirect costs of warm temperatures for high-elevation populations of a solitary bee.

    Science.gov (United States)

    Forrest, Jessica R K; Chisholm, Sarah P M

    2017-02-01

    Warm temperatures are required for insect flight. Consequently, warming could benefit many high-latitude and high-altitude insects by increasing opportunities for foraging or oviposition. However, warming can also alter species interactions, including interactions with natural enemies, making the net effect of rising temperatures on population growth rate difficult to predict. We investigated the temperature-dependence of nesting activity and lifetime reproductive output over 3 yr in subalpine populations of a pollen-specialist bee, Osmia iridis. Rates of nest provisioning increased with ambient temperatures and with availability of floral resources, as expected. However, warmer conditions did not increase lifetime reproductive output. Lifetime offspring production was best explained by rates of brood parasitism (by the wasp Sapyga), which increased with temperature. Direct observations of bee and parasite activity suggest that although activity of both species is favored by warmer temperatures, bees can be active at lower ambient temperatures, while wasps are active only at higher temperatures. Thus, direct benefits to the bees of warmer temperatures were nullified by indirect costs associated with increased parasite activity. To date, most studies of climate-change effects on pollinators have focused on changing interactions between pollinators and their floral host-plants (i.e., bottom-up processes). Our results suggest that natural enemies (i.e., top-down forces) can play a key role in pollinator population regulation and should not be overlooked in forecasts of pollinator responses to climate change. © 2016 by the Ecological Society of America.

  18. Self-organized Ruthenium-Barium Core-Shell Nanoparticles on a Mesoporous Calcium Amide Matrix for Efficient Low-Temperature Ammonia Synthesis.

    Science.gov (United States)

    Kitano, Masaaki; Inoue, Yasunori; Sasase, Masato; Kishida, Kazuhisa; Kobayashi, Yasukazu; Nishiyama, Kohei; Tada, Tomofumi; Kawamura, Shigeki; Yokoyama, Toshiharu; Hara, Michikazu; Hosono, Hideo

    2018-01-22

    A low-temperature ammonia synthesis process is required for on-site synthesis. Here, we report that barium-doped calcium amide (Ba-Ca(NH2)2) significantly enhances the ammonia synthesis activities of Ru and Co by two-orders of magnitude more than that of a conventional Ru catalyst below 300ºC. Furthermore, the present catalysts are superior to that of the wüstite-based Fe catalyst known as a highly active industrial catalyst at low temperatures and pressures. Nanosized Ru-Ba core-shell structures are self-organized on the support during hydrogen pretreatment, and the support material is simultaneously converted into a mesoporous structure with a high surface area (>100 m2 g-1). These unique self-organized nanostructures account for the high catalytic performance in low-temperature ammonia synthesis. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Design of a low-temperature plasma (LTP) probe with adjustable output temperature and variable beam diameter for the direct detection of organic molecules.

    Science.gov (United States)

    Martínez-Jarquín, Sandra; Winkler, Robert

    2013-03-15

    The direct detection of organic molecules by mass spectrometry requires ionization methods which are compatible with ambient conditions. A relatively new strategy is the use of a free low-temperature plasma beam for ionization. The objective is to design a safe and adjustable plasma beam to enable optimal ionization and desorption parameters for specific molecules. A plasma probe based on a dielectric barrier discharge was designed, where the plasma is guided through an internal second tube. This setup permits different beam diameter settings and the control of the plasma temperature. The ionization and desorption of pure organic compounds, as well as their direct detection from roasted coffee beans, were tested. The presented plasma probe provides improved safety with respect to arcing, ozone generation and electric shock, compared with conventional designs. The functionality of previously reported devices is expanded. A defined plasma diameter can be set by choosing the appropriate insert, while the input voltage controls the plasma temperature. The variation of measurement parameters enables the optimized direct detection of target compounds from roasted coffee beans, such as caffeine, guaiacol and vanillin. The presented low-temperature plasma probe allows the fine-tuning of ionization and desorption parameters, according to the target molecules. Possible applications include: (1) The ambient ionization and desorption of organic compounds with different volatility and (2) The direct analysis of food products such as roasted coffee beans. Copyright © 2013 John Wiley & Sons, Ltd.

  20. Automated synthesis of [(18)F]DCFPyL via direct radiofluorination and validation in preclinical prostate cancer models.

    Science.gov (United States)

    Bouvet, Vincent; Wuest, Melinda; Jans, Hans-Soenke; Janzen, Nancy; Genady, Afaf R; Valliant, John F; Benard, Francois; Wuest, Frank

    2016-12-01

    Prostate-specific membrane antigen (PSMA) is frequently overexpressed and upregulated in prostate cancer. To date, various (18)F- and (68)Ga-labeled urea-based radiotracers for PET imaging of PSMA have been developed and entered clinical trials. Here, we describe an automated synthesis of [(18)F]DCFPyL via direct radiofluorination and validation in preclinical models of prostate cancer. [(18)F]DCFPyL was synthesized via direct nucleophilic heteroaromatic substitution reaction in a single reactor TRACERlab FXFN automated synthesis unit. Radiopharmacological evaluation of [(18)F]DCFPyL involved internalization experiments, dynamic PET imaging in LNCaP (PSMA+) and PC3 (PSMA-) tumor-bearing BALB/c nude mice, biodistribution studies, and metabolic profiling. In addition, reversible two-tissue compartmental model analysis was used to quantify pharmacokinetics of [(18)F]DCFPyL in LNCaP and PC3 tumor models. Automated radiosynthesis afforded radiotracer [(18)F]DCFPyL in decay-corrected radiochemical yields of 23 ± 5 % (n = 10) within 55 min, including HPLC purification. Dynamic PET analysis revealed rapid and high uptake of radioactivity (SUV5min 0.95) in LNCaP tumors which increased over time (SUV60min 1.1). Radioactivity uptake in LNCaP tumors was blocked in the presence of nonradioactive DCFPyL (SUV60min 0.22). The muscle as reference tissue showed rapid and continuous clearance over time (SUV60min 0.06). Fast blood clearance of radioactivity resulted in tumor-blood ratios of 1.0 after 10 min and 8.3 after 60 min. PC3 tumors also showed continuous clearance of radioactivity over time (SUV60min 0.11). Kinetic analysis of PET data revealed the two-tissue compartmental model as best fit with K 1 = 0.12, k 2 = 0.18, k 3 = 0.08, and k 4 = 0.004 min(-1), confirming molecular trapping of [(18)F]DCFPyL in PSMA+ LNCaP cells. [(18)F]DCFPyL can be prepared for clinical applications simply and in good radiochemical yields via a direct radiofluorination

  1. Melt-Pool Temperature and Size Measurement During Direct Laser Sintering

    Energy Technology Data Exchange (ETDEWEB)

    List, III, Frederick Alyious [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dinwiddie, Ralph Barton [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Carver, Keith [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gockel, Joy E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-08-01

    Additive manufacturing has demonstrated the ability to fabricate complex geometries and components not possible with conventional casting and machining. In many cases, industry has demonstrated the ability to fabricate complex geometries with improved efficiency and performance. However, qualification and certification of processes is challenging, leaving companies to focus on certification of material though design allowable based approaches. This significantly reduces the business case for additive manufacturing. Therefore, real time monitoring of the melt pool can be used to detect the development of flaws, such as porosity or un-sintered powder and aid in the certification process. Characteristics of the melt pool in the Direct Laser Sintering (DLS) process is also of great interest to modelers who are developing simulation models needed to improve and perfect the DLS process. Such models could provide a means to rapidly develop the optimum processing parameters for new alloy powders and optimize processing parameters for specific part geometries. Stratonics’ ThermaViz system will be integrated with the Renishaw DLS system in order to demonstrate its ability to measure melt pool size, shape and temperature. These results will be compared with data from an existing IR camera to determine the best approach for the determination of these critical parameters.

  2. Direct-contact high-temperature thermal energy storage heat exchanger. Final subcontract report

    Energy Technology Data Exchange (ETDEWEB)

    Alario, J.; Brown, R.

    1983-09-01

    A 10-kWh scale model high-temperature direct-contact latent-heat-exchange thermal energy storage system was designed and fabricated. A research program was structured in three separate phases to permit: Phase I - the inspection and evaluation of the origin al hardware, which suffered extensive corrosion and damage in a previous experimental program; Phase II - redesign and fabrication of a modified system; and Phase III - detailed test evaluation. On the basis of the findings in Phase I, the design was modified to eliminate previous deficiencies. A test plan was also prepared that contained detailed information concerning instrumentation (type and location), measured parameters, and equipment operating procedures. Phase II entailed component procurement and fabrication, system assembly, and instrumentation. At the end of Phase II, the system was in a ready-for-test condition but the program was terminated before the start of the Phase III test evaluation. Since testing was never implemented, this report presents only the results for the design and fabrication phases of the program.

  3. Non-syngas direct steam reforming of methanol to hydrogen and carbon dioxide at low temperature.

    Science.gov (United States)

    Yu, Kai Man Kerry; Tong, Weiyi; West, Adam; Cheung, Kevin; Li, Tong; Smith, George; Guo, Yanglong; Tsang, Shik Chi Edman

    2012-01-01

    A non-syngas direct steam reforming route is investigated for the conversion of methanol to hydrogen and carbon dioxide over a CuZnGaO(x) catalyst at 150-200 °C. This route is in marked contrast with the conventional complex route involving steam reformation to syngas (CO/H2) at high temperature, followed by water gas shift and CO cleanup stages for hydrogen production. Here we report that high quality hydrogen and carbon dioxide can be produced in a single-step reaction over the catalyst, with no detectable CO (below detection limit of 1 ppm). This can be used to supply proton exchange membrane fuel cells for mobile applications without invoking any CO shift and cleanup stages. The working catalyst contains, on average, 3-4 nm copper particles, alongside extremely small size of copper clusters stabilized on a defective ZnGa2O4 spinel oxide surface, providing hydrogen productivity of 393.6 ml g(-1)-cat h(-1) at 150 °C.

  4. Direct measurements of the effect of biomass burning over the Amazon on the atmospheric temperature profile

    Directory of Open Access Journals (Sweden)

    L. Remer

    2009-11-01

    Full Text Available Aerosols suspended in the atmosphere interact with solar radiation and clouds, thus change the radiation energy fluxes in the atmospheric column. In this paper we measure changes in the atmospheric temperature profile as a function of the smoke loading and the cloudiness, over the Amazon basin, during the dry seasons (August and September of 2005–2008. We show that as the aerosol optical depth (AOD increases from 0.02 to a value of ~0.6, there is a decrease of ~4°C at 1000 hPa, and an increase of ~1.5°C at 850 hPa. The warming of the aerosol layer at 850 hPa is likely due to aerosol absorption when the particles are exposed to direct illumination by the sun. The large values of cooling in the lower layers could be explained by a combination of aerosol extinction of the solar flux in the layers aloft together with an aerosol-induced increase of cloud cover which shade the lower atmosphere. We estimate that the increase in cloud fraction due to aerosol contributes about half of the observed cooling in the lower layers.

  5. Synthesis of an extra-large molecular sieve using proton sponges as organic structure-directing agents.

    Science.gov (United States)

    Martínez-Franco, Raquel; Moliner, Manuel; Yun, Yifeng; Sun, Junliang; Wan, Wei; Zou, Xiaodong; Corma, Avelino

    2013-03-05

    The synthesis of crystalline microporous materials containing large pores is in high demand by industry, especially for the use of these materials as catalysts in chemical processes involving bulky molecules. An extra-large-pore silicoaluminophosphate with 16-ring openings, ITQ-51, has been synthesized by the use of bulky aromatic proton sponges as organic structure-directing agents. Proton sponges show exceptional properties for directing extra-large zeolites because of their unusually high basicity combined with their large size and rigidity. This extra-large-pore material is stable after calcination, being one of the very few examples of hydrothermally stable molecular sieves containing extra-large pores. The structure of ITQ-51 was solved from submicrometer-sized crystals using the rotation electron diffraction method. Finally, several hypothetical zeolites related to ITQ-51 have been proposed.

  6. Biomass-directed synthesis of 20 g high-quality boron nitride nanosheets for thermoconductive polymeric composites.

    Science.gov (United States)

    Wang, Xue-Bin; Weng, Qunhong; Wang, Xi; Li, Xia; Zhang, Jun; Liu, Fei; Jiang, Xiang-Fen; Guo, Hongxuan; Xu, Ningsheng; Golberg, Dmitri; Bando, Yoshio

    2014-09-23

    Electrically insulating boron nitride (BN) nanosheets possess thermal conductivity similar to and thermal and chemical stabilities superior to those of electrically conductive graphenes. Currently the production and application of BN nanosheets are rather limited due to the complexity of the BN binary compound growth, as opposed to massive graphene production. Here we have developed the original strategy "biomass-directed on-site synthesis" toward mass production of high-crystal-quality BN nanosheets. The strikingly effective, reliable, and high-throughput (dozens of grams) synthesis is directed by diverse biomass sources through the carbothermal reduction of gaseous boron oxide species. The produced BN nanosheets are single crystalline, laterally large, and atomically thin. Additionally, they assemble themselves into the same macroscopic shapes peculiar to original biomasses. The nanosheets are further utilized for making thermoconductive and electrically insulating epoxy/BN composites with a 14-fold increase in thermal conductivity, which are envisaged to be particularly valuable for future high-performance electronic packaging materials.

  7. Understanding fluxes as media for directed synthesis: in situ local structure of molten potassium polysulfides.

    Science.gov (United States)

    Shoemaker, Daniel P; Chung, Duck Young; Mitchell, J F; Bray, Travis H; Soderholm, L; Chupas, Peter J; Kanatzidis, Mercouri G

    2012-06-06

    Rational exploratory synthesis of new materials requires routes to discover novel phases and systematic methods to tailor their structures and properties. Synthetic reactions in molten fluxes have proven to be an excellent route to new inorganic materials because they promote diffusion and can serve as an additional reactant, but little is known about the mechanisms of compound formation, crystal precipitation, or behavior of fluxes themselves at conditions relevant to synthesis. In this study we examine the properties of a salt flux system that has proven extremely fertile for growth of new materials: the potassium polysulfides spanning K(2)S(3) and K(2)S(5), which melt between 302 and 206 °C. We present in situ Raman spectroscopy of melts between K(2)S(3) and K(2)S(5) and find strong coupling between n in K(2)S(n) and the molten local structure, implying that the S(n)(2-) chains in the crystalline state are mirrored in the melt. In any reactive flux system, K(2)S(n) included, a signature of changing species in the melt implies that their evolution during a reaction can be characterized and eventually controlled for selective formation of compounds. We use in situ X-ray total scattering to obtain the pair distribution function of molten K(2)S(5) and model the length of S(n)(2-) chains in the melt using reverse Monte Carlo simulations. Combining in situ Raman and total scattering provides a path to understanding the behavior of reactive media and should be broadly applied for more informed, targeted synthesis of compounds in a wide variety of inorganic fluxes.

  8. A C78 fullerene precursor: toward the direct synthesis of higher fullerenes.

    Science.gov (United States)

    Amsharov, Konstantin Yu; Jansen, Martin

    2008-04-04

    A C78 fullerene related structure (of C78:1 and C78:4, the last undiscovered C78 IPR isomer) has been synthesized and investigated as a pyrolytic precursor. The pyrolysis of precursor containing all 78 carbon atoms in the required positions and 93 of the 117 C-C bonds, needed for fullerene formation, showed selectivity for C78 fullerene formation. In independent experiments it has been shown that the flash pyrolysis of C78 fullerene is not affected by Stone-Wales rearrangement and loss of C2 fragments and, thus, is very promising for the synthesis of individual isomers of higher fullerenes.

  9. Direct Synthesis of Lithium-Intercalated Graphene for Electrochemical Energy Storage Application

    Science.gov (United States)

    2011-01-01

    walled carbon nanotubes (SWNT/MWNT) dispersed in Li/NH3 form “nanotube salts” that react with alkyl or aryl halides to generate free radicals that add...nanotubes.25 In this paper , we describe a new synthesis method for the preparation of lithium-ion-interca- lated graphene sheets and their suitability as...Preparation and Characterization of Graphene Oxide Paper . Nature 2007, 448, 457–460. 6. Stankovich, S.; Dikin, D. A.; Dommett, G. H. B.; Kohlhaas, K. M

  10. An atom economical method for the direct synthesis of quinoline derivatives from substituted o-nitrotoluenes.

    Science.gov (United States)

    Liu, Guiyan; Yi, Maocong; Liu, Lu; Wang, Jingjing; Wang, Jianhui

    2015-02-18

    A highly efficient one-pot procedure for the preparation of substituted quinolines from substituted o-nitrotoluenes with electron-withdrawing groups and olefins (acrylic esters and acrylonitriles) using a cesium catalyst has been developed. A plausible [2+4] cycloaddition mechanism is proposed. This method uses nitroaromatic compounds as the starting materials to give quinoline derivatives in good to high yields under mild conditions with no transition metal catalysis. It provides an atom economical pathway for the synthesis of quinoline derivatives which could be used in industrial processes.

  11. Synthesis and Characterisation of Poly(L-Lysine) for Directed Transfection of siRNA

    OpenAIRE

    McCarthy, Sarah

    2010-01-01

    This work focuses primarily on the synthesis of the cell penetrating peptide poly(L-lysine). This 30mer peptide (K³º) has been shown to be extremely useful in delivery of genetic material to the cell for gene therapy. So far it has shown transgene expression of up to twelve weeks, using DNA, which was delivered to the brain.[l] Lung cells have also been success full transfected by ths method.[2,3] In this research we aim to use a polymer conjugate of K³º for the delivery of small interferi...

  12. Direct and Stereospecific [3+2] Synthesis of Pyrrolidines from Simple Unactivated Alkenes.

    Science.gov (United States)

    Otero-Fraga, Jorge; Suárez-Pantiga, Samuel; Montesinos-Magraner, Marc; Rhein, Dennis; Mendoza, Abraham

    2017-10-09

    Pyrrolidines are important heterocyclic compounds with endless applications in organic synthesis, metal catalysis, and organocatalysis. Their potential as ligands for first-row transition-metal catalysts inspired a new method to access complex poly-heterocyclic pyrrolidines in one step from available materials. This fundamental step forward is based on the discovery of an essential organoaluminum promoter that engages unactivated and electron-rich olefins in intermolecular [3+2] cycloadditions. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Low-temperature CVD synthesis of patterned core-shell VO2@ZnO nanotetrapods and enhanced temperature-dependent field-emission properties

    Science.gov (United States)

    Yin, Haihong; Yu, Ke; Song, Changqing; Wang, Zhiliang; Zhu, Ziqiang

    2014-09-01

    VO2 nanostructures are attractive materials because of their reversible metal-insulator transition (MIT) and wide applications in devices. When they are used as field emitters, a new type of temperature-controlled field emission device can be fabricated. Vapor transport methods used to synthesize traditional VO2 nanostructures are energy-intensive, low yield, and produce simple morphology (quasi-1D) that exhibits substrate clamping; thus they are not suitable for field emission applications. To overcome these limitations, ZnO nanotetrapods were used as templates, and patterned core-shell VO2@ZnO nanotetrapods were successfully grown on an ITO/glass substrate via a low-temperature CVD synthesis. SEM, TEM, EDX, XPS analyses and X-ray diffraction revealed that the cores and shells of these nanotetrapods were single crystal wurtzite-type ZnO and polycrystalline VO2, respectively. The VO2@ZnO nanotetrapods show strongly MIT-related FE properties, the emission current density at low temperature is significantly enhanced in comparison with pure VO2 nanostructures, and the emission current density increased by about 20 times as the ambient temperature increased from 25 to 105 °C at a fixed field of 5 V μm-1. Although the VO2@ZnO nanotetrapods show a worse FE performance at low temperatures compared with pure ZnO nanotetrapods, the FE performance was substantially improved at high temperatures, which was attributed to the MIT-related band bending near the interface and the abrupt resistance change across the MIT.

  14. Synthesis of imogolite fibers from decimolar concentration at low temperature and ambient pressure: a promising route for inexpensive nanotubes.

    Science.gov (United States)

    Levard, Clément; Masion, Armand; Rose, Jérôme; Doelsch, Emmanuel; Borschneck, Daniel; Dominici, Christian; Ziarelli, Fabio; Bottero, Jean-Yves

    2009-12-02

    To date, the successful low-temperature synthesis of the aluminosilicate imogolite nanotubes always involved initial concentrations of the reagents in the millimolar range, higher concentrations being reported to lead to the formation of the less well characterized allophane phase. The present work shows that reaction kinetics and not initial concentration control the formation of the nanotubes: substantial amounts of well formed imogolite were obtained from a decimolar initial concentration, i.e. 100 times higher than the "standard" protocol. The allophane-like spheroids expected from the high reagent concentration were not observed in this work, and proto-imogolite was obtained instead.

  15. Low-temperature plasma synthesis of carbon nanotubes and graphene based materials and their fuel cell applications.

    Science.gov (United States)

    Wang, Qi; Wang, Xiangke; Chai, Zhifang; Hu, Wenping

    2013-12-07

    Carbon nanotubes (CNTs) and graphene, and materials based on these, are largely used in multidisciplinary fields. Many techniques have been put forward to synthesize them. Among all kinds of approaches, the low-temperature plasma approach is widely used due to its numerous advantages, such as highly distributed active species, reduced energy requirements, enhanced catalyst activation, shortened operation time and decreased environmental pollution. This tutorial review focuses on the recent development of plasma synthesis of CNTs and graphene based materials and their electrochemical application in fuel cells.

  16. An Efficient Protocol for the Synthesis of Quinoxaline Derivatives at Room Temperature Using Recyclable Alumina-Supported Heteropolyoxometalates

    Directory of Open Access Journals (Sweden)

    Diego M. Ruiz

    2012-01-01

    Full Text Available We report a suitable quinoxaline synthesis using molybdophosphovanadates supported on commercial alumina cylinders as catalysts. These catalysts were prepared by incipient wetness impregnation. The catalytic test was performed under different reaction conditions in order to know the performance of the synthesized catalysts. The method shows high yields of quinoxaline derivatives under heterogeneous conditions. Quinoxaline formation was obtained using benzyl, o-phenylenediamine, and toluene as reaction solvent at room temperature. The CuH2PMo11VO40 supported on alumina showed higher activity in the tested reaction. Finally, various quinoxalines were prepared under mild conditions and with excellent yields.

  17. Synthesis of Fused Pyrimidinone and Quinolone Derivatives in an Automated High-Temperature and High-Pressure Flow Reactor.

    Science.gov (United States)

    Tsoung, Jennifer; Bogdan, Andrew R; Kantor, Stanislaw; Wang, Ying; Charaschanya, Manwika; Djuric, Stevan W

    2017-01-20

    Fused pyrimidinone and quinolone derivatives that are of potential interest to pharmaceutical research were synthesized within minutes in up to 96% yield in an automated Phoenix high-temperature and high-pressure continuous flow reactor. Heterocyclic scaffolds that are either hard to synthesize or require multisteps are readily accessible using a common set of reaction conditions. The use of low-boiling solvents along with the high conversions of these reactions allowed for facile workup and isolation. The methods reported herein are highly amenable for fast and efficient heterocycle synthesis as well as compound scale-ups.

  18. Low-temperature synthesis of carbon nanotubes on indium tin oxide electrodes for organic solar cells.

    Science.gov (United States)

    Capasso, Andrea; Salamandra, Luigi; Di Carlo, Aldo; Bell, John Marcus; Motta, Nunzio

    2012-01-01

    The electrical performance of indium tin oxide (ITO) coated glass was improved by including a controlled layer of carbon nanotubes directly on top of the ITO film. Multiwall carbon nanotubes (MWCNTs) were synthesized by chemical vapor deposition, using ultrathin Fe layers as catalyst. The process parameters (temperature, gas flow and duration) were carefully refined to obtain the appropriate size and density of MWCNTs with a minimum decrease of the light harvesting in the cell. When used as anodes for organic solar cells based on poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM), the MWCNT-enhanced electrodes are found to improve the charge-carrier extraction from the photoactive blend, thanks to the additional percolation paths provided by the CNTs. The work function of as-modified ITO surfaces was measured by the Kelvin probe method to be 4.95 eV, resulting in an improved matching to the highest occupied molecular orbital level of the P3HT. This is in turn expected to increase the hole transport and collection at the anode, contributing to the significant increase of current density and open-circuit voltage observed in test cells created with such MWCNT-enhanced electrodes.

  19. Low-temperature synthesis of carbon nanotubes on indium tin oxide electrodes for organic solar cells

    Directory of Open Access Journals (Sweden)

    Andrea Capasso

    2012-07-01

    Full Text Available The electrical performance of indium tin oxide (ITO coated glass was improved by including a controlled layer of carbon nanotubes directly on top of the ITO film. Multiwall carbon nanotubes (MWCNTs were synthesized by chemical vapor deposition, using ultrathin Fe layers as catalyst. The process parameters (temperature, gas flow and duration were carefully refined to obtain the appropriate size and density of MWCNTs with a minimum decrease of the light harvesting in the cell. When used as anodes for organic solar cells based on poly(3-hexylthiophene (P3HT and phenyl-C61-butyric acid methyl ester (PCBM, the MWCNT-enhanced electrodes are found to improve the charge-carrier extraction from the photoactive blend, thanks to the additional percolation paths provided by the CNTs. The work function of as-modified ITO surfaces was measured by the Kelvin probe method to be 4.95 eV, resulting in an improved matching to the highest occupied molecular orbital level of the P3HT. This is in turn expected to increase the hole transport and collection at the anode, contributing to the significant increase of current density and open-circuit voltage observed in test cells created with such MWCNT-enhanced electrodes.

  20. Low temperature synthesis of seed mediated CuO bundle of nanowires, their structural characterisation and cholesterol detection

    Energy Technology Data Exchange (ETDEWEB)

    Ibupoto, Z.H., E-mail: zafar.hussin.ibupoto@liu.se [Department of Science and Technology, Linköping University, Campus Norrköping, SE-60174 Norrköping (Sweden); Khun, K. [Department of Science and Technology, Linköping University, Campus Norrköping, SE-60174 Norrköping (Sweden); Liu, X. [Department of Physics, Chemistry, and Biology (IFM), Linköping University, 58183 Linköping Sweden (Sweden); Willander, M. [Department of Science and Technology, Linköping University, Campus Norrköping, SE-60174 Norrköping (Sweden)

    2013-10-15

    In this study, we have successfully synthesised CuO bundle of nanowires using simple, cheap and low temperature hydrothermal growth method. The growth parameters such as precursor concentration and time for duration of growth were optimised. The field emission scanning electron microscopy (FESEM) has demonstrated that the CuO bundles of nanowires are highly dense, uniform and perpendicularly oriented to the substrate. The high resolution transmission electron microscopy (HRTEM) has demonstrated that the CuO nanostructures consist of bundle of nanowires and their growth pattern is along the [010] direction. The X-ray diffraction (XRD) technique described that CuO bundle of nanowires possess the monoclinic crystal phase. The surface and chemical composition analyses were carried out with X-ray photoelectron spectroscopy (XPS) technique and the obtained results suggested the pure crystal state of CuO nanostructures. In addition, the CuO nanowires were used for the cholesterol sensing application by immobilising the cholesterol oxidase through electrostatic attraction. The infrared reflection absorption spectroscopy study has also revealed that CuO nanostructures are consisting of only Cu-O bonding and has also shown the possible interaction of cholesterol oxidase with the sharp edge surface of CuO bundle of nanowires. The proposed cholesterol sensor has demonstrated the wide range of detection of cholesterol with good sensitivity of 33.88 ± 0.96 mV/decade. Moreover, the CuO bundle of nanowires based sensor electrode has revealed good repeatability, reproducibility, stability, selectivity and a fast response time of less than 10 s. The cholesterol sensor based on the immobilised cholesterol oxidase has good potential applicability for the determination of cholesterol from the human serum and other biological samples. - Highlights: • This study describes the synthesis of bundle of CuO nanowires by hydrothermal method. • CuO nanostructures exhibit good alignment and

  1. A new synthesis of carbon encapsulated Fe5C2 nanoparticles for high-temperature Fischer-Tropsch synthesis

    Science.gov (United States)

    Hong, Seok Yong; Chun, Dong Hyun; Yang, Jung-Il; Jung, Heon; Lee, Ho-Tae; Hong, Sungjun; Jang, Sanha; Lim, Jung Tae; Kim, Chul Sung; Park, Ji Chan

    2015-10-01

    Using a simple thermal treatment under a CO flow, uniform micrometer-sized iron oxalate dihydrate cubes prepared by hydrothermal reaction were transformed into Fe5C2@C nanoparticles to form a mesoporous framework; the final structure was successfully applied to the high-temperature Fischer-Tropsch reaction and it showed high activity (CO conversion = 96%, FTY = 1.5 × 10-4 molCO gFe-1 s-1) and stability.Using a simple thermal treatment under a CO flow, uniform micrometer-sized iron oxalate dihydrate cubes prepared by hydrothermal reaction were transformed into Fe5C2@C nanoparticles to form a mesoporous framework; the final structure was successfully applied to the high-temperature Fischer-Tropsch reaction and it showed high activity (CO conversion = 96%, FTY = 1.5 × 10-4 molCO gFe-1 s-1) and stability. Electronic supplementary information (ESI) available: Details of experimental procedures, SEM images of FeNi and FeCo oxalate hydrate particles, particle size and pore size distributions, FT activity and selectivity, hydrocarbon product distribution, ASF plot, and Mössbauer parameters of the Fe5C2@C catalyst. See DOI: 10.1039/c5nr05787f

  2. Direct synthesis of inverse hexagonally ordered diblock copolymer/polyoxometalate nanocomposite films

    NARCIS (Netherlands)

    Lunkenbein, T.; Kamperman, M.M.G.; Li, Z.; Bojer, C.; Drechsler, M.; Forster, S.; Wiesner, U.; Muller, A.; Breu, J.

    2012-01-01

    Nanostructured inverse hexagonal polyoxometalate composite films were cast directly from solution using poly(butadiene-block-2-(dimethylamino)ethyl methacrylate) (PB-b-PDMAEMA) diblock copolymers as structure directing agents for phosphomolybdic acid (H(3)[PMo(12)O(40)], H(3)PMo). H(3)PMo units are

  3. Palladium(II)-Catalyzed C-H Bond Activation/C-C and C-O Bond Formation Reaction Cascade: Direct Synthesis of Coumestans.

    Science.gov (United States)

    Neog, Kashmiri; Borah, Ashwini; Gogoi, Pranjal

    2016-12-02

    A palladium catalyzed cascade reaction of 4-hydroxycoumarins and in situ generated arynes has been developed for the direct synthesis of coumestans. This cascade strategy proceeds via C-H bond activation/C-O and C-C bond formations in a single reaction vessel. This methodology affords moderate to good yields of coumestans and is tolerant of a variety of functional groups including halide. The methodology was applied to the synthesis of natural product flemichapparin C.

  4. The effects of cannabinoids on body temperature and brain catecholamine synthesis.

    Science.gov (United States)

    Bloom, A S; Johnson, K M; Dewey, W L

    1978-04-01

    delta9-Tetrahydrocannabinol, 11-OH-delta9-tetrahydrocannabinol and 9-nor-9beta-OH-hexahydrocannabinol produced hypothermia and increased catecholamine synthesis in mouse brain. The potencies of the effects of these compounds were correlated. Cannabinol and cannabidiol were inactive in both tests.

  5. Green synthesis of Au nanostructures at room temperature using biodegradable plant surfactants

    Science.gov (United States)

    One-step green synthesis of gold (Au) nanostructures is described using naturally occurring biodegradable plant surfactants such as VeruSOL-3™ (mixture of d-limonene and plant-based surfactants), VeruSOL-10™, VeruSOL-11™ and VeruSOL-12™ (individual plant-based surfactants deri...

  6. Dual direction blower system powered by solar energy to reduce car cabin temperature in open parking condition

    Science.gov (United States)

    Hamdan, N. S.; Radzi, M. F. M.; Damanhuri, A. A. M.; Mokhtar, S. N.

    2017-10-01

    El-nino phenomenon that strikes Malaysia with temperature recorded more than 35°C can lead to extreme temperature rise in car cabin up to 80°C. Various problems will arise due to this extreme rising of temperature such as the occupant are vulnerable to heat stroke, emission of benzene gas that can cause cancer due to reaction of high temperature with interior compartments, and damage of compartments in the car. The current solution available to reduce car cabin temperature including tinted of window and portable heat rejection device that are available in the market. As an alternative to reduce car cabin temperature, this project modifies the car’s air conditioning blower motor into dual direction powered by solar energy and identifies its influence to temperature inside the car, parked under scorching sun. By reducing the car cabin temperature up to 10°C which equal to 14% of reduction in the car cabin temperature, this simple proposed system aims to provide comfort to users due to its capability in improving the quality of air and moisture in the car cabin.

  7. A study on the stability and green synthesis of silver nanoparticles using Ziziphora tenuior (Zt) extract at room temperature.

    Science.gov (United States)

    Sadeghi, Babak; Gholamhoseinpoor, F

    2015-01-05

    Biomolecules present in plant extracts can be used to reduce metal ions to nanoparticles in a single-step green synthesis process. This biogenic reduction of metal ion to base metal is quite rapid, readily conducted at room temperature and pressure, and easily scaled up. Mediated Synthesis by plant extracts is environmentally benign. The involved reducing agents include the various water soluble plant metabolites (e.g. alkaloids, phenolic compounds, terpenoids) and co-enzymes. Silver (Ag) nanoparticles have the particular focus of plant-based syntheses. Extracts of a diverse range of Ziziphora tenuior (Zt) have been successfully used in making nanoparticles. The aim of this study was to investigate the antioxidant properties of this plant and its ability to synthesize silver nanoparticles. Z.tenuior leaves were used to prepare the aqueous extract for this study. Silver nanoparticles were characterized with different techniques such as UV-vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), Scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Transmission electron microscopy experiments showed that these nanoparticles are spherical and uniformly distributed and its size is from 8 to 40 nm. FT-IR spectroscopy revealed that silver nanoparticles were functionalized with biomolecules that have primary amine group (NH₂), carbonyl group, -OH groups and other stabilizing functional groups. X-ray diffraction pattern showed high purity and face centered cubic structure of silver nanoparticles with size of 38 nm. In addition to plant extracts, live plants can be used for the synthesis. Here were view the methods of making nanoparticles using plant extracts. The scanning electron microscopy (SEM) implies the right of forming silver nanoparticles. The results of TEM, SEM, FT-IR, UV-VIS and XRD confirm that the leaves extract of Zt can synthesis silver nanoparticles. Copyright © 2014 Elsevier B.V. All rights

  8. Direct gas-phase synthesis of single-phase {beta}-FeSi{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Bywalez, Robert, E-mail: robert.bywalez@uni-due.de; Orthner, Hans; Mehmedovic, Ervin [University of Duisburg-Essen, IVG, Institute for Combustion and Gas Dynamics - Reactive Fluids (Germany); Imlau, Robert; Kovacs, Andras; Luysberg, Martina [Forschungszentrum Juelich, Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Gruenberg Institute 5 (Germany); Wiggers, Hartmut [University of Duisburg-Essen, IVG, Institute for Combustion and Gas Dynamics - Reactive Fluids (Germany)

    2013-09-15

    For the first time, phase-pure {beta}-FeSi{sub 2} nanoparticles were successfully produced by gas-phase synthesis. We present a method to fabricate larger quantities of semiconducting {beta}-FeSi{sub 2} nanoparticles, with crystallite sizes between 10 and 30 nm, for solar and thermoelectric applications utilizing a hot-wall reactor. A general outline for the production of those particles by thermal decomposition of silane and iron pentacarbonyl is provided based on kinetic data. The synthesized particles are investigated by X-ray diffraction and transmission electron microscopy, providing evidence that the as-prepared materials are indeed {beta}-FeSi{sub 2}, while revealing morphological characteristics inherent to the nanoparticles created.

  9. Direct synthesis of esters and amides from unprotected hydroxyaromatic and -aliphatic carboxylic acids.

    Science.gov (United States)

    Katritzky, Alan R; Singh, Sanjay K; Cai, Chunming; Bobrov, Sergey

    2006-04-28

    A facile method for the activation of hydroxy-substituted carboxylic acids using benzotriazole chemistry without prior protection of the hydroxy substituents is presented. The N-acylbenzotriazole intermediates 2a-g, 6a-d, and 9a-c have been used for high-yielding synthesis of both aliphatic (3a-l) and aromatic (7a-h, 10a-f) hydroxy carboxamides. High yields of aromatic hydroxy esters 12a-h and 13a-i were obtained using either neat alcohols in neutral microwave conditions or nucleophilic alkoxides and the intermediate N-(arylacyl)benzotriazoles. Moderate yields were obtained in the case of aliphatic hydroxy esters 11a,b and thiolesters 11e-g from the intermediates 2a-c.

  10. An effective low-temperature solution synthesis of Co-doped [0001]-oriented ZnO nanorods

    Science.gov (United States)

    Alnoor, Hatim; Savoyant, Adrien; Liu, Xianjie; Pozina, Galia; Willander, Magnus; Nur, Omer

    2017-06-01

    We demonstrate an efficient possibility to synthesize vertically aligned pure zinc oxide (ZnO) and Co-doped ZnO nanorods (NRs) using the low-temperature aqueous chemical synthesis (90 °C). Two different mixing methods of the synthesis solutions were investigated for the Co-doped samples. The synthesized samples were compared to pure ZnO NRs regarding the Co incorporation and crystal quality. Electron paramagnetic resonance (EPR) measurements confirmed the substitution of Co2+ inside the ZnO NRs, giving a highly anisotropic magnetic Co2+ signal. The substitution of Zn2+ by Co2+ was observed to be combined with a drastic reduction in the core-defect (CD) signal (g ˜ 1.956) which is seen in pure ZnO NRs. As revealed by the cathodoluminescence (CL), the incorporation of Co causes a slight red-shift of the UV peak position combined with an enhancement in the intensity of the defect-related yellow-orange emission compared to pure ZnO NRs. Furthermore, the EPR and the CL measurements allow a possible model of the defect configuration in the samples. It is proposed that the as-synthesized pure ZnO NRs likely contain Zn interstitial (Zni+) as CDs and oxygen vacancy (VO) or oxygen interstitial (Oi) as surface defects. As a result, Co was found to likely occupy the Zni+, leading to the observed CDs reduction and hence enhancing the crystal quality. These results open the possibility of synthesis of highly crystalline quality ZnO NRs-based diluted magnetic semiconductors using the low-temperature aqueous chemical method.

  11. Mixed phase Pt-Ru catalyst for direct methanol fuel cell anode by flame aerosol synthesis

    DEFF Research Database (Denmark)

    Chakraborty, Debasish; Bischoff, H.; Chorkendorff, Ib

    2005-01-01

    A spray-flame aerosol catalyzation technique was studied for producing Pt-Ru anode electrodes for the direct methanol fuel cell. Catalysts were produced as aerosol nanoparticles in a spray-flame reactor and deposited directly as a thin layer on the gas diffusion layer. The as-prepared catalyst......Ru1/Vulcan carbon. The kinetics of methanol oxidation on the mixed phase catalyst was also explored by electrochemical impedance spectroscopy. (c) 2005 The Electrochemical Society....

  12. Influence of calcination temperature on the morphology and energy storage properties of cobalt oxide nanostructures directly grown over carbon cloth substrates

    KAUST Repository

    Baby, Rakhi Raghavan

    2013-09-23

    Nanostructured and mesoporous cobalt oxide (Co3O4) nanowire in flower-like arrangements have been directly grown over flexible carbon cloth collectors using solvothermal synthesis for supercapacitor applications. Changes in the morphology and porosity of the nanowire assemblies have been induced by manipulating the calcination temperature (200–300 °C) of the one-dimensional (1-D) structures, resulting in significant impact on their surface area and pseudocapacitive properties. As the calcination temperature increases from 200 to 250 °C, the flower morphology gradually modifies to the point where the electrolyte could access almost all the nanowires over the entire sample volume, resulting in an increase in specific capacitance from 334 to 605 Fg−1, depending on the nanowire electrode morphology. The 300 °C calcination results in the breakdown of the mesoporous morphology and decreases the efficiency of electrolyte diffusion, resulting in a drop in pseudocapacitance after 300 °C. A peak energy density of 44 Wh kg−1 has been obtained at a power density of 20 kW kg−1 for the 250 °C calcined sample.

  13. Effects of hydrothermal temperature and time on hydrothermal synthesis of colloidal hydroxyapatite nanorods in the presence of sodium citrate.

    Science.gov (United States)

    Jin, Xiaoying; Chen, Xiaohu; Cheng, Yute; Wang, Longshen; Hu, Bing; Tan, Junjun

    2015-07-15

    In this paper, colloidal hydrophilic hydroxyapatite nanorods were synthesized in the presence of sodium citrate via thermal-decomplexing method. The influences of hydrothermal temperature and time on the synthesis of HA nanorods were characterized in terms of structure, size, morphology, and colloidal stability through TEM, XRD, zeta potential, DLS and long-term standing test. Results show that increasing hydrothermal temperature and prolonging hydrothermal time would evidently improve crystallinity and enlarge size of HA nanorods but decrease the colloidal stability of nanorods. It is worth noting that the effect of raising the hydrothermal temperature and time on diameter increase is far greater than that on length increase; meanwhile, the colloidal stability would be seriously deteriorated when the hydrothermal temperature is over 180 °C for 24 h or when the hydrothermal temperature is 150 °C for over 48 h, in these cases, dispersion of HA nanorods would apparently settle within 2 months. The origin responding to the results is that although the charge density of HA nanorods is not obviously affected, the dynamic diameters of HA particles increase greatly, which reduces colloidal stability of the dispersion. This work provides new insights into the role of hydrothermal temperature and time on tailoring morphology, crystallinity and colloidal stability of HA nanorods. Moreover, it would be helpful to optimize the experimental procedure both on scientific and industrial applications related to HA. For example, on the premise of satisfying the necessary requirements including crystallinity, size, morphology and colloid stability, it is feasible to compress the consumption of experimental time through raising the hydrothermal temperature, or vice versa. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Synthesis of Hafnium-Based Ceramic Materials for Ultra-High Temperature Aerospace Applications

    Science.gov (United States)

    Johnson, Sylvia; Feldman, Jay

    2004-01-01

    This project involved the synthesis of hafnium (Hf)-based ceramic powders and Hf-based precursor solutions that were suitable for preparation of Hf-based ceramics. The Hf-based ceramic materials of interest in this project were hafnium carbide (with nominal composition HE) and hafnium dioxide (HfO2). The materials were prepared at Georgia Institute of Technology and then supplied to research collaborators Dr. Sylvia Johnson and Dr. Jay Feldman) at NASA Ames Research Center.

  15. Feasibility of using ammonia-water mixture in high temperature concentrated solar power plants with direct vapour generation

    DEFF Research Database (Denmark)

    Modi, Anish; Knudsen, Thomas; Haglind, Fredrik

    2014-01-01

    is to use direct vapour generation with water/steam as both the heat transfer fluid in the solar receivers and the cycle working fluid. This enables to operate the plant with higher turbine inlet temperatures. Available literature suggests that it is feasible to use ammonia-water mixture at high...... temperatures without corroding the equipment by using suitable additives with the mixture. This paper assesses the thermodynamic feasibility of using ammonia-water mixture in high temperature (450 °C) and high pressure (over 100 bar) concentrated solar power plants with direct vapour generation. The following......Concentrated solar power plants have attracted an increasing interest in the past few years – both with respect to the design of various plant components, and extending the operation hours by employing different types of storage systems. One approach to improve the overall plant performance...

  16. Direct screening of tetracyclines in water and bovine milk using room temperature phosphorescence detection

    Energy Technology Data Exchange (ETDEWEB)

    Traviesa-Alvarez, J.M. [Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, c/Julian Claveria 8, 33006 Oviedo (Spain); Costa-Fernandez, J.M. [Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, c/Julian Claveria 8, 33006 Oviedo (Spain); Pereiro, R. [Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, c/Julian Claveria 8, 33006 Oviedo (Spain); Sanz-Medel, A. [Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, c/Julian Claveria 8, 33006 Oviedo (Spain)]. E-mail: asm@uniovi.es

    2007-04-18

    A fast and simple flow-through optosensor was designed and characterized for the direct screening of four tetracycline (TCC) antibiotics (tetracycline, oxytetracycline, chlortetracycline and doxycycline) in water and bovine milk samples. The proposed optosensor provides rapid binary yes/no overall responses, being appropriate for the screening of this family of antibiotics above or below a pre-set concentration threshold. The experimental set-up is based on a flow-injection manifold coupled on-line to a phosphorescence detector. Aliquots of the samples are pretreated with Eu(III) to form room temperature phosphorescent metal chelates and injected in the flow manifold. Those chelates are then on-line retained on a conventional flow-cell (packed with polymeric Amberlite XAD-4 particles) which is placed inside the cell holder of the phosphorimeter. After the emission is registered, the antibiotic-metal complexes are eluted from the packed resin with 1 M HCl (for milk samples a second regeneration step, using methanol, should be performed). A sample throughput of about 20 samples per hour was obtained. Optimum experimental conditions include a pH 9, a Eu(III) concentration of 2 x 10{sup -4} M and 8 mM sodium sulphite as chemical deoxygenant. The phosphorescence emitted by the europium-TCC complexes was measured at 394 and 617 nm for excitation and emission wavelengths, respectively. The unreliability region, given by the probability of false positives and false negatives, respectively (set at 5% in both cases) was in the range between 0.2 and 11.6 nM for detection of tetracyclines in water samples (at a cut-off level of 4 nM) and in the range between 165 and 238 nM for detection of tetracyclines in milk (cut-off level fixed at the normative EU level of 200 nM). Finally, the applicability of the proposed screening optosensor was tested for the reliable control of tetracyclines in contaminated and uncontaminated water and milk samples.

  17. Temperature Dependence in Heterogeneous Nucleation with Application to the Direct Determination of Cluster Energy on Nearly Molecular Scale.

    Science.gov (United States)

    McGraw, Robert L; Winkler, Paul M; Wagner, Paul E

    2017-12-04

    A re-examination of measurements of heterogeneous nucleation of water vapor on silver nanoparticles is presented here using a model-free framework that derives the energy of critical cluster formation directly from measurements of nucleation probability. Temperature dependence is correlated with cluster stabilization by the nanoparticle seed and previously found cases of unusual increasing nucleation onset saturation ratio with increasing temperature are explained. A necessary condition for the unusual positive temperature dependence is identified, namely that the critical cluster be more stable, on a per molecule basis, than the bulk liquid to exhibit the effect. Temperature dependence is next examined in the classical Fletcher model, modified here to make the energy of cluster formation explicit in the model.  The contact angle used in the Fletcher model is identified as the microscopic contact angle, which can be directly obtained from heterogeneous nucleation experimental data by a recently developed analysis method. Here an equivalent condition, increasing contact angle with temperature, is found necessary for occurrence of unusual temperature dependence. Our findings have immediate applications to atmospheric particle formation and nanoparticle detection in condensation particle counters (CPCs).

  18. Improved PID controller design for unstable time delay processes based on direct synthesis method and maximum sensitivity

    Science.gov (United States)

    Vanavil, B.; Krishna Chaitanya, K.; Seshagiri Rao, A.

    2015-06-01

    In this paper, a proportional-integral-derivative controller in series with a lead-lag filter is designed for control of the open-loop unstable processes with time delay based on direct synthesis method. Study of the performance of the designed controllers has been carried out on various unstable processes. Set-point weighting is considered to reduce the undesirable overshoot. The proposed scheme consists of only one tuning parameter, and systematic guidelines are provided for selection of the tuning parameter based on the peak value of the sensitivity function (Ms). Robustness analysis has been carried out based on sensitivity and complementary sensitivity functions. Nominal and robust control performances are achieved with the proposed method and improved closed-loop performances are obtained when compared to the recently reported methods in the literature.

  19. Enhancement of carbon nanotube FET performance via direct synthesis of poly (sodium 4-styrenesulfonate) in the transistor channel

    Science.gov (United States)

    Toader, M.; Schubel, R.; Hartmann, M.; Scharfenberg, L.; Jordan, R.; Mertig, M.; Schulz, S. E.; Gessner, T.; Hermann, S.

    2016-09-01

    Direct synthesis of poly (sodium 4-styrenesulfonate) (P(NaSS)) inside the channel of single-walled carbon nanotube (SWCNT) field-effect transistors (FETs), is shown to be highly beneficial in improving the device parameters. Starting with monomeric compounds, the FET-channel was in-situ polymerized, using the self-initiated photografting and photopolymerization process. Upon formation of the P(NaSS) polymer matrix, we report improved device-to-device consistency, lower variability in the threshold voltage, higher drain currents and higher on/off ratios. Annealing in vacuum was shown to further improve the device performance and induce an ambipolar behavior. Moreover, those FET devices showed a long-term stability even under ambient environment.

  20. Palladium-catalyzed direct arylation of azine and azole N-oxides: reaction development, scope and applications in synthesis.

    Science.gov (United States)

    Campeau, Louis-Charles; Stuart, David R; Leclerc, Jean-Philippe; Bertrand-Laperle, Mégan; Villemure, Elisia; Sun, Ho-Yan; Lasserre, Sandrine; Guimond, Nicolas; Lecavallier, Melanie; Fagnou, Keith

    2009-03-11

    Palladium-catalyzed direct arylation reactions are described with a broad range of azine and azole N-oxides. In addition to aspects of functional group compatibility, issues of regioselectivity have been explored when nonsymmetrical azine N-oxides are used. In these cases, both the choice of ligand and the nature of the azine substituents play important roles in determining the regioisomeric distribution. When azole N-oxides are employed, preferential reaction is observed for arylation at C2 which occurs under very mild conditions. Subsequent reactions are observed to occur at C5 followed by arylation at C4. The potential utility of this methodology is illustrated by its use in the synthesis of a potent sodium channel inhibitor 1 and a Tie2 Tyrosine Kinase inhibitor 2.

  1. Zirconocene and Si-tethered diynes: a happy match directed toward organometallic chemistry and organic synthesis.

    Science.gov (United States)

    Zhang, Wen-Xiong; Zhang, Shaoguang; Xi, Zhenfeng

    2011-07-19

    Characterizing reactive organometallic intermediates is critical for understanding the mechanistic aspects of metal-mediated organic reactions. Moreover, the isolation of reactive organometallic intermediates can often result in the ability to design new synthetic methods. In this Account, we outline synthetic methods that we developed for a variety of diverse Zr/Si organo-bimetallic compounds and Si/N heteroatom-organic compounds through the detailed study of zirconacyclobutene-silacyclobutene fused compounds. Two basic components are involved in this chemistry. The first is the Si-tethered diyne, which owes its rich reactive palette to the combination of the Si-C bond and the C≡C triple bond. The second is the low-valent zirconocene species Cp(2)Zr(II), which has proven very useful in organic synthesis. The reaction of these two components affords the zirconacyclobutene-silacyclobutene fused compound, which is the key reactive Zr/Si organo-bimetallic intermediate discussed here. We discuss the three types of reactions that have been developed for the zirconacyclobutene-silacyclobutene fused intermediate. The reaction with nitriles (the C≡N triple bond) is introduced in the first section. In this one-pot reaction, up to four different components can be combined: the Si-tethered diyne can be reacted with three identical nitriles, with differing nitriles, or with a nitrile and other unsaturated organic substrates such as formamides, isocyanides, acid chlorides, aldehydes, carbodiimides, and azides. Several unexpected multiring, fused Zr/Si organo-bimetallic intermediates were isolated and characterized. A wide variety of N-heterocycles, such as 5-azaindole, pyrrole, and pyrroloazepine derivatives, were obtained. We then discuss the reaction with alkynes (the C≡C triple bond). A consecutive skeletal rearrangement, differing from that observed in the reactions with nitriles, takes place in this reaction. Finally, we discuss the reaction with the C═X substrates

  2. Ionothermal Synthesis of MnAPO-SOD Molecular Sieve without the Aid of Organic Structure-Directing Agents.

    Science.gov (United States)

    Liu, Hao; Tian, Zhijian; Wang, Lei; Wang, Yasong; Li, Dawei; Ma, Huaijun; Xu, Renshun

    2016-02-15

    An SOD-type metalloaluminophosphate molecular sieve (denoted as SOD-Mn) was ionothermally synthesized by introducing manganese(II) cations into the reaction mixture via MnO-acid or MnO2-reductant reactions. Composition and structure analyses results show that two kinds of manganese(II) cations exist in the SOD-Mn structure. Part of the manganese(II) cations isomorphously substitute the framework aluminum(III) with a substitution degree of ∼30%. The rest of the manganese(II) cations occupy a fraction of the sod cages in their hydrated forms. A comprehensive investigation of the synthesis parameters, crystal sizes, and crystallization kinetics indicates that the in situ released hydrated manganese(II) cations direct the formation of SOD-Mn. Such structure-directing effect may be inhibited by both the fluorination of manganese(II) cations and the water accumulation during crystallization. In the fluoride anion-containing reaction mixture with a low ionic liquid content, the crystallization process is strongly suppressed, and large SOD-Mn single crystals of over 200 μm in size are yielded. SOD-Mn is free from organics and shows improved thermal stability compared with metalloaluminophosphates synthesized by using organic structure-directing agents.

  3. Direct synthesis of graphene nanosheets support Pd nanodendrites for electrocatalytic formic acid oxidation

    Science.gov (United States)

    Yang, Su-Dong; Chen, Lin

    2015-11-01

    We report a solvothermal method preparation of dendritic Pd nanoparticles (DPNs) and spherical Pd nanoparticles (SPNs) supported on reduced graphene oxide (RGO). Drastically different morphologies of Pd NPs with nanodendritic structures or spherical structures were observed on graphene by controlling the reduction degree of graphene oxide (GO) under mild conditions. In addition to being a commonplace substrate, GO plays a more important role that relies on its surface groups, which serves as a shape-directing agent to direct the dendritic growth. As a result, the obtained DPNs/RGO catalyst exhibits a significantly enhanced electro-catalytic behavior for the oxidation of formic acid compared to the SPNs/RGO catalyst.

  4. Observation of directional exitance and retrieval of soil and foliage component temperatures: case studies with bi-angular ATSR radiometric data

    NARCIS (Netherlands)

    Jia, L.; Menenti, M.; Su, Z.; Li, Z.L.

    2002-01-01

    A mixture of foliage and soil is thermally heterogeneous, so the radiometric temperature of the mixture depends on view direction. A simple linear mixture model was applied to estimate the component surface temperatures of foliage and soil temperatures. The potential of directional observations in

  5. Template directed synthesis of plasmonic gold nanotubes with tunable IR absorbance.

    Science.gov (United States)

    Bridges, Colin R; Schon, Tyler B; DiCarmine, Paul M; Seferos, Dwight S

    2013-04-01

    A nearly parallel array of pores can be produced by anodizing aluminum foils in acidic environments. Applications of anodic aluminum oxide (AAO) membranes have been under development since the 1990's and have become a common method to template the synthesis of high aspect ratio nanostructures, mostly by electrochemical growth or pore-wetting. Recently, these membranes have become commercially available in a wide range of pore sizes and densities, leading to an extensive library of functional nanostructures being synthesized from AAO membranes. These include composite nanorods, nanowires and nanotubes made of metals, inorganic materials or polymers. Nanoporous membranes have been used to synthesize nanoparticle and nanotube arrays that perform well as refractive index sensors, plasmonic biosensors, or surface enhanced Raman spectroscopy (SERS) substrates, as well as a wide range of other fields such as photo-thermal heating, permselective transport, catalysis, microfluidics, and electrochemical sensing. Here, we report a novel procedure to prepare gold nanotubes in AAO membranes. Hollow nanostructures have potential application in plasmonic and SERS sensing, and we anticipate these gold nanotubes will allow for high sensitivity and strong plasmon signals, arising from decreased material dampening.

  6. Direct synthesis of antimicrobial coatings based on tailored bi-elemental nanoparticles

    Directory of Open Access Journals (Sweden)

    Giulio Benetti

    2017-03-01

    Full Text Available Ultrathin coatings based on bi-elemental nanoparticles (NPs are very promising to limit the surface-related spread of bacterial pathogens, particularly in nosocomial environments. However, tailoring the synthesis, composition, adhesion to substrate, and antimicrobial spectrum of the coating is an open challenge. Herein, we report on a radically new nanostructured coating, obtained by a one-step gas-phase deposition technique, and composed of bi-elemental Janus type Ag/Ti NPs. The NPs are characterized by a cluster-in-cluster mixing phase with metallic Ag nano-crystals embedded in amorphous TiO2 and present a promising antimicrobial activity including also multidrug resistant strains. We demonstrate the flexibility of the method to tune the embedded Ag nano-crystals dimension, the total relative composition of the coating, and the substrate type, opening the possibility of tailoring the dimension, composition, antimicrobial spectrum, and other physical/chemical properties of such multi-elemental systems. This work is expected to significantly spread the range of applications of NPs coatings, not only as an effective tool in the prevention of healthcare-associated infections but also in other technologically relevant fields like sensors or nano-/micro joining.

  7. Direct synthesis of antimicrobial coatings based on tailored bi-elemental nanoparticles

    Science.gov (United States)

    Benetti, Giulio; Cavaliere, Emanuele; Canteri, Adalberto; Landini, Giulia; Rossolini, Gian Maria; Pallecchi, Lucia; Chiodi, Mirco; Van Bael, Margriet J.; Winckelmans, Naomi; Bals, Sara; Gavioli, Luca

    2017-03-01

    Ultrathin coatings based on bi-elemental nanoparticles (NPs) are very promising to limit the surface-related spread of bacterial pathogens, particularly in nosocomial environments. However, tailoring the synthesis, composition, adhesion to substrate, and antimicrobial spectrum of the coating is an open challenge. Herein, we report on a radically new nanostructured coating, obtained by a one-step gas-phase deposition technique, and composed of bi-elemental Janus type Ag/Ti NPs. The NPs are characterized by a cluster-in-cluster mixing phase with metallic Ag nano-crystals embedded in amorphous TiO2 and present a promising antimicrobial activity including also multidrug resistant strains. We demonstrate the flexibility of the method to tune the embedded Ag nano-crystals dimension, the total relative composition of the coating, and the substrate type, opening the possibility of tailoring the dimension, composition, antimicrobial spectrum, and other physical/chemical properties of such multi-elemental systems. This work is expected to significantly spread the range of applications of NPs coatings, not only as an effective tool in the prevention of healthcare-associated infections but also in other technologically relevant fields like sensors or nano-/micro joining.

  8. Nonlocal control of electron temperature in short direct current glow discharge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Demidov, V. I. [Department of Optics and Spectroscopy, St. Petersburg State University, St. Petersburg 199034 (Russian Federation); International Laboratory “Nonlocal Plasma in Nanotechnology and Medicine”, ITMO University, Kronverkskiy pr. 49, St. Petersburg 197101 (Russian Federation); Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506 (United States); Kudryavtsev, A. A.; Stepanova, O. M. [Department of Optics and Spectroscopy, St. Petersburg State University, St. Petersburg 199034 (Russian Federation); Kurlyandskaya, I. P. [International Laboratory “Nonlocal Plasma in Nanotechnology and Medicine”, ITMO University, Kronverkskiy pr. 49, St. Petersburg 197101 (Russian Federation); St. Petersburg University of State Fire Service of EMERCOM RF, Murmansk Branch, Murmansk 183040 (Russian Federation)

    2014-09-15

    To demonstrate controlling the electron temperature in nonlocal plasma, experiments have been performed on a short (without positive column) dc glow discharge with a cold cathode by applying different voltages to the conducting discharge wall. The experiments have been performed for low-pressure noble gas discharges. The applied voltage can modify trapping the energetic electrons emitted from the cathode sheath and arising from the atomic and molecular processes in the plasma within the device volume. This phenomenon results in the energetic electrons heating the slow plasma electrons, which consequently modifies the electron temperature. Furthermore, a numerical model of the discharge has demonstrated the electron temperature modification for the above case.

  9. Towards behavioral synthesis of asynchronous circuits - an implementation template targeting syntax directed compilation

    DEFF Research Database (Denmark)

    Nielsen, Sune Fallgaard; Sparsø, Jens; Madsen, Jan

    2004-01-01

    domain by introducing a computation model, which resembles the synchronous datapath and control architecture, but which is completely asynchronous. The datapath and control architecture is then expressed in the Balsa-language, and using syntax directed compilation a corresponding handshake circuit...

  10. Direct synthesis of graphitic mesoporous carbon from green phenolic resins exposed to subsequent UV and IR laser irradiations

    Science.gov (United States)

    Sopronyi, Mihai; Sima, Felix; Vaulot, Cyril; Delmotte, Luc; Bahouka, Armel; Matei Ghimbeu, Camelia

    2016-12-01

    The design of mesoporous carbon materials with controlled textural and structural features by rapid, cost-effective and eco-friendly means is highly demanded for many fields of applications. We report herein on the fast and tailored synthesis of mesoporous carbon by UV and IR laser assisted irradiations of a solution consisting of green phenolic resins and surfactant agent. By tailoring the UV laser parameters such as energy, pulse repetition rate or exposure time carbon materials with different pore size, architecture and wall thickness were obtained. By increasing irradiation dose, the mesopore size diminishes in the favor of wall thickness while the morphology shifts from worm-like to an ordered hexagonal one. This was related to the intensification of phenolic resin cross-linking which induces the reduction of H-bonding with the template as highlighted by 13C and 1H NMR. In addition, mesoporous carbon with graphitic structure was obtained by IR laser irradiation at room temperature and in very short time periods compared to the classical long thermal treatment at very high temperatures. Therefore, the carbon texture and structure can be tuned only by playing with laser parameters, without extra chemicals, as usually required.

  11. Lipase-catalyzed Synthesis of Oleoyl-lysophosphatidylcholine by Direct Esterification in Solvent-free Medium without Water Removal.

    Science.gov (United States)

    Mnasri, Taha; Ergan, Françoise; Herault, Josiane; Pencreac'h, Gaëlle

    2017-09-01

    In this work, the synthesis of oleoyl-lysophosphatidylcholine by lipase-catalyzed esterification of glycerophosphocholine (GPC) and free oleic acid in a reaction medium without solvent is presented. The complete solubilisation of GPC, which is a crucial issue in non-polar liquids such as melted free fatty acids, was reached by heating the GPC/oleic acid mixture at high temperature during a short time. The immobilized lipase from Rhizomucor miehei (Lipozyme RM-IM) was shown to catalyze the reaction more efficiently than the immobilized lipases from Thermomyces lanuginosus (Lipozyme TL-IM) and Candida antarctica (Novozym 435). The condition reactions leading to the highest yield were as follows: substrate ratio: 1/20 (GPC/oleic acid); amount of catalyst: 10% (w/w of substrates); temperature: 50°C. Under these conditions, a yield of 75% of oleoyl-lysophosphatidylcholine was achieved in 24 h under stirring and almost no dioleoyl-lysophosphatidylcholine was produced. Unlike other studies dealing with the esterification of GPC with free fatty acids, the removal of the water produced while the reaction proceeds was not necessary to reach high yields.

  12. Direct synthesis of graphitic mesoporous carbon from green phenolic resins exposed to subsequent UV and IR laser irradiations.

    Science.gov (United States)

    Sopronyi, Mihai; Sima, Felix; Vaulot, Cyril; Delmotte, Luc; Bahouka, Armel; Matei Ghimbeu, Camelia

    2016-12-21

    The design of mesoporous carbon materials with controlled textural and structural features by rapid, cost-effective and eco-friendly means is highly demanded for many fields of applications. We report herein on the fast and tailored synthesis of mesoporous carbon by UV and IR laser assisted irradiations of a solution consisting of green phenolic resins and surfactant agent. By tailoring the UV laser parameters such as energy, pulse repetition rate or exposure time carbon materials with different pore size, architecture and wall thickness were obtained. By increasing irradiation dose, the mesopore size diminishes in the favor of wall thickness while the morphology shifts from worm-like to an ordered hexagonal one. This was related to the intensification of phenolic resin cross-linking which induces the reduction of H-bonding with the template as highlighted by (13)C and (1)H NMR. In addition, mesoporous carbon with graphitic structure was obtained by IR laser irradiation at room temperature and in very short time periods compared to the classical long thermal treatment at very high temperatures. Therefore, the carbon texture and structure can be tuned only by playing with laser parameters, without extra chemicals, as usually required.

  13. Synthesis and electrochemical properties of Co3O4 nanoparticles by hydrothermal method at different temperatures

    Science.gov (United States)

    Duan, Qiuyan; Chen, Haiyan

    2017-06-01

    In this work, Co3O4 nanoparticles were synthesized by hydrothermal method at different temperatures. The synthesized Co3O4 nanoparticles were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectrometer (XPS) and nitrogen adsorption-desorption. The Co3O4 nanoparticles prepared at the hydrothermal temperature of 140 °C and at the annealing temperature of 350 °C have a shorter crystal spacing distance associated to the (220) crystal planes, larger BET surface area and more bivalent cobalt on the surface than these of Co3O4 nanoparticles prepared at higher hydrothermal temperature or higher annealing temperature. The supercapacitor performances of synthesized Co3O4 nanoparticles were analysed by cyclic voltammograms (CVs), Galvano static charge/discharge (GCD) and the electrochemical impedance spectroscopy (EIS) in 6 M KOH aqueous electrolyte solution. The Co3O4 nanoparticles produced at lower temperatures exhibit good pseudo capacitance behaviour. Also, owning to the low hydrothermal temperature and the annealing temperature of Co3O4 nanoparticles, they can be relatively low cost in favour of a promising candidate for electrochemical supercapacitors.

  14. Low Temperature Synthesis and Properties of Gadolinium-Doped Cerium Oxide Nanoparticles

    DEFF Research Database (Denmark)

    Machado, M. F. S.; Moraes, L. P. R.; Monteiro, N. K.

    2017-01-01

    Gadolinium-doped cerium oxide (GDC) is an attractive ceramic material for solid oxide fuel cells (SOFCs) both as the electrolyte and in composite electrodes operating at low and intermediate temperatures. GDC exhibits high oxygen ion conductivity at a wide range of temperatures and displays a hig...

  15. Thermal infrared remote sensing for riverscape analysis of water temperature heterogeneity: current research and future directions

    Science.gov (United States)

    Dugdale, S.; Hannah, D. M.; Malcolm, I.; Bergeron, N.; St-Hilaire, A.

    2016-12-01

    Climate change will increase summer water temperatures in northern latitude rivers. It is likely that this will have a negative impact on fish species such as salmonids, which are sensitive to elevated temperatures. Salmonids currently avoid heat stress by opportunistically using cool water zones that arise from the spatio-temporal mosaic of thermal habitats present within rivers. However, there is a general lack of information about the processes driving this thermal habitat heterogeneity or how these spatio-temporal patterns might vary under climate change. In this paper, we document how thermal infrared imaging has previously been used to better understand the processes driving river temperature patterns. We then identify key knowledge gaps that this technology can help to address in the future. First, we demonstrate how repeat thermal imagery has revealed the role of short-term hydrometeorological variability in influencing longitudinal river temperature patterns, showing that precipitation depth is strongly correlated with the degree of longitudinal temperature heterogeneity. Second, we document how thermal infrared imagery of a large watershed in Eastern Canada has shed new light on the landscape processes driving the spatial distribution of cool water patches, revealing that the distribution of cool patches is strongly linked to channel confinement, channel curvature and the proximity of dry tributary valleys. Finally, we detail gaps in current understanding of spatio-temporal patterns of river temperature heterogeneity. We explain how advances in unmanned aerial vehicle technology and deterministic temperature modelling will be combined to address these current limitations, shedding new light on the landscape processes driving geographical variability in patterns of river temperature heterogeneity. We then detail how such advances will help to identify rivers that will be resilient to future climatic warming, improving current and future strategies for

  16. Science for a wilder Anthropocene: Synthesis and future directions for trophic rewilding research.

    Science.gov (United States)

    Svenning, Jens-Christian; Pedersen, Pil B M; Donlan, C Josh; Ejrnæs, Rasmus; Faurby, Søren; Galetti, Mauro; Hansen, Dennis M; Sandel, Brody; Sandom, Christopher J; Terborgh, John W; Vera, Frans W M

    2016-01-26

    Trophic rewilding is an ecological restoration strategy that uses species introductions to restore top-down trophic interactions and associated trophic cascades to promote self-regulating biodiverse ecosystems. Given the importance of large animals in trophic cascades and their widespread losses and resulting trophic downgrading, it often focuses on restoring functional megafaunas. Trophic rewilding is increasingly being implemented for conservation, but remains controversial. Here, we provide a synthesis of its current scientific basis, highlighting trophic cascades as the key conceptual framework, discussing the main lessons learned from ongoing rewilding projects, systematically reviewing the current literature, and highlighting unintentional rewilding and spontaneous wildlife comebacks as underused sources of information. Together, these lines of evidence show that trophic cascades may be restored via species reintroductions and ecological replacements. It is clear, however, that megafauna effects may be affected by poorly understood trophic complexity effects and interactions with landscape settings, human activities, and other factors. Unfortunately, empirical research on trophic rewilding is still rare, fragmented, and geographically biased, with the literature dominated by essays and opinion pieces. We highlight the need for applied programs to include hypothesis testing and science-based monitoring, and outline priorities for future research, notably assessing the role of trophic complexity, interplay with landscape settings, land use, and climate change, as well as developing the global scope for rewilding and tools to optimize benefits and reduce human-wildlife conflicts. Finally, we recommend developing a decision framework for species selection, building on functional and phylogenetic information and with attention to the potential contribution from synthetic biology.

  17. Application of mental illness stigma theory to Chinese societies: synthesis and new directions.

    Science.gov (United States)

    Yang, L H

    2007-11-01

    The rapidly-evolving literature concerning stigma towards psychiatric illnesses among Chinese groups has demonstrated pervasive negative attitudes and discriminatory treatment towards people with mental illness. However, a systematic integration of current stigma theories and empirical findings to examine how stigma processes may occur among Chinese ethnic groups has yet to be undertaken. This paper first introduces several major stigma models, and specifies how these models provide a theoretical basis as to how stigma broadly acts on individuals with schizophrenia through three main mechanisms: direct individual discrimination, internalisation of negative stereotypes, and structural discrimination. In Chinese societies, the particular manifestations of stigma associated with schizophrenia are shaped by cultural meanings embedded within Confucianism, the centrality of "face", and pejorative aetiological beliefs of mental illnesses. These cultural meanings are reflected in severe and culturally-specific expressions of stigma in Chinese societies. Implications and directions to advance stigma research within Chinese cultural settings are provided.

  18. Synthesis of quinoxaline 1,4-di-n-oxide derivatives on solid support using room temperature and microwave-assisted solvent-free procedures

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Caro, Lilia C.; Sanchez-Sanchez, Mario; Bocanegra-Garcia, Virgilio; Rivera, Gildardo [Universidad Autonoma de Tamaulipas, Reynosa (Mexico). Dept. de Farmacia y Quimica Medicinal; Monge, Antonio [Universidad de Navarra, Pamplona (Spain). Centro de Investigacion en Farmacobiologia Aplicada. Unidad de Investigacion y Desarrollo de Medicamentos

    2011-07-01

    We describe the synthesis of 12 new ethyl and methyl quinoxaline-7-carboxylate 1,4-di-N-oxide derivatives on solid supports with room temperature and microwave-assisted solvent-free procedures. Results show that solid supports have good catalytic activity in the formation of quinoxaline 1,4-di-N-oxide derivatives. We found that florisil and montmorillonite KSF and K10 could be used as new, easily available, inexpensive alternatives of catalysts. Additionally, room temperature and microwave-irradiation solvent-free synthesis was more efficient than a conventional procedure (Beirut reaction), reducing reaction time and increasing yield. (author)

  19. A practical one-pot synthesis of azides directly from alcohols

    Indian Academy of Sciences (India)

    azides, direct methods for the said transformation are only a few. The most familiar and versatile one is the. Mitsunobu displacement,4 where hydrazoic acid is used as ..... Lim J-O, Choi H-K, Suh Y-G, Park H-G, Oh U, Kim. H-D, Park Y-H, Ha H-J, Kin Y-H, Toth A, Wang Y, Tran. R, Pearce L V, Lundberg D J and Blumberg P M ...

  20. Highly integrated CO2 capture and conversion: Direct synthesis of cyclic carbonates from industrial flue gas

    KAUST Repository

    Barthel, Alexander

    2016-02-08

    Robust and selective catalytic systems based on early transition metal halides (Y, Sc, Zr) and organic nucleophiles were found able to quantitatively capture CO2 from diluted streams via formation of hemicarbonate species and to convert it to cyclic organic carbonates under ambient conditions. This observation was exploited in the direct and selective chemical fixation of flue gas CO2 collected from an industrial exhaust, affording high degrees of CO2 capture and conversion.

  1. Synthesis and characterisation of alkaline anionic-exchange membranes for direct alcohol fuel cells

    CSIR Research Space (South Africa)

    Nonjola, P

    2007-12-01

    Full Text Available of alkaline anionic-exchange membranes for direct alcohol fuel cells P. Nonjola*, M. Mathe, S. Hietkamp Materials Science and Manufacturing, Council for Scientific and Industrial Research, P.O. Box 395, Pretoria 0001, South Africa *snonjola... exchange membranes from poly(arylene ether), by the conventional aromatic nucleophilic displacement route via chloromethylation and quaternary amination. The primary objective was to acquire basic information on structure-property relationships to permit...

  2. In Situ Synthesis of Uranium Carbide and its High Temperature Cubic Phase

    Energy Technology Data Exchange (ETDEWEB)

    Reiche, Helmut Matthias [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Vogel, Sven C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-03-25

    New in situ data for the U-C system are presented, with the goal of improving knowledge of the phase diagram to enable production of new ceramic fuels. The none quenchable, cubic, δ-phase, which in turn is fundamental to computational methods, was identified. Rich datasets of the formation synthesis of uranium carbide yield kinetics data which allow the benchmarking of modeling, thermodynamic parameters etc. The order-disorder transition (carbon sublattice melting) was observed due to equal sensitivity of neutrons to both elements. This dynamic has not been accurately described in some recent simulation-based publications.

  3. Polyethylenimine-assisted synthesis of transparent ZnO nanowhiskers at ambient temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Xiulan, E-mail: whoxiulan@163.com [College of Materials Science and Engineering, Nanjing Tech University, Xin-mo-fan Road No.5, Nanjing 210009 (China); Shen, Xiaodong; Li, Hongtao [College of Materials Science and Engineering, Nanjing Tech University, Xin-mo-fan Road No.5, Nanjing 210009 (China); Masuda, Yoshitake; Ohji, Tatsuki; Kato, Kazumi [National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560 (Japan)

    2014-05-02

    Transparent ZnO nanowhiskers were synthesized at ambient temperature (5–30 °C) assisted with pH buffer of polyethylenimine from an aqueous solution of sodium hydroxide and zinc acetate. X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy revealed their crystalline phase, morphology and formation mechanism. The ZnO nuclei were formed at the initial stage in a wide low temperature range by in-situ forced hydrolysis of anhydrous zinc acetate template layer. Subsequently ZnO nanowhiskers were formed on the F-doped SnO{sub 2}-coated glass substrate by heterogeneous nucleation and growth. Lower temperature was found to favor the hydrolysis, whereas higher temperature was found to promote the growth of ZnO. Such synthesized ZnO possessed good crystalline structure. The length, diameter, and density (number of whiskers per unit area) of ZnO nanowhiskers are controllable by simply varying the deposition time and/or solution temperature. - Highlights: • ZnO nanowhisker film was synthesized at ambient temperature (5–30 °C). • Polyethylenimine improved forced hydrolysis of template layer and ZnO film growth. • The parameters of ZnO films are function of reaction time and temperature. • This approach features with low cost and a more substrate materials choice.

  4. One-step synthesis of multi-emission carbon nanodots for ratiometric temperature sensing

    Science.gov (United States)

    Nguyen, Vanthan; Yan, Lihe; Xu, Huanhuan; Yue, Mengmeng

    2018-01-01

    Measuring temperature with greater precision at localized small length scales or in a nonperturbative manner is a necessity in widespread applications, such as integrated photonic devices, micro/nano electronics, biology, and medical diagnostics. To this context, use of nanoscale fluorescent temperature probes is regarded as the most promising method for temperature sensing because they are noninvasive, accurate, and enable remote micro/nanoscale imaging. Here, we propose a novel ratiometric fluorescent sensor for nanothermometry using carbon nanodots (C-dots). The C-dots were synthesized by one-step method using femtosecond laser ablation and exhibit unique multi-emission property due to emissions from abundant functional groups on its surface. The as-prepared C-dots demonstrate excellent ratiometric temperature sensing under single wavelength excitation that achieves high temperature sensitivity with a 1.48% change per °C ratiometric response over wide-ranging temperature (5-85 °C) in aqueous buffer. The ratiometric sensor shows excellent reversibility and stability, holding great promise for the accurate measurement of temperature in many practical applications.

  5. Direct asymmetry measurement of temperature and density spatial distributions in inertial confinement fusion plasmas from pinhole space-resolved spectra

    CERN Document Server

    Nagayama, T; Florido, R; Mayes, D; Tommasini, R; Koch, J A; Delettrez, J A; Regan, S P; Smalyuk, V A

    2014-01-01

    Two-dimensional space-resolved temperature and density images of an inertial confinement fusion (ICF) implosion core have been diagnosed for the first time. Argon-doped, direct-drive ICF experiments were performed at the Omega Laser Facility and a collection of two-dimensional space-resolved spectra were obtained from an array of gated, spectrally resolved pinhole images recorded by a multi-monochromatic x-ray imager. Detailed spectral analysis revealed asymmetries of the core not just in shape and size but in the temperature and density spatial distributions, thus characterizing the core with an unprecedented level of detail.

  6. Current direction, wind direction, temperature, and salinity data from moored current meter casts in the Gulf of Mexico during the Brine Disposal project, 01 February 1981 - 01 February 1981 (NODC Accession 8100516)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, temperature, wind direction, and salinity data were collected using moored current meter casts in the Gulf of Mexico from February 1, 1981 to...

  7. Current direction, benthic organisms, temperature, and wind direction data from moored current meter casts in the Gulf of Mexico during the Brine Disposal project, 22 September 1977 - 30 November 1978 (NODC Accession 7900110)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, benthic organisms, temperature, and wind direction data were collected using moored current meter casts in the Gulf of Mexico from September 22,...

  8. Direct Microscale Measurement of Mouse Oocyte Membrane Permeability to Water and Ethylene Glycol at Subzero Temperatures Using Cryomicroscopy.

    Science.gov (United States)

    Han, X

      BACKGROUND: Investigation of cell osmotic behavior at subzero temperatures is of critical importance to the optimization of cooling procedures for cryopreservation. Based on established thermodynamic models, plasma membrane permeability coefficients for water and cryoprotectant agent (CPA) (Lcpa, Pp) and their activation energies (EaLp, EaPcpa) are essential to predict the change of cell volume and composition of intracellular solutions corresponding to different cooling procedures. However, currently available methods to measure Lp at subzero temperatures suffer from technical difficulties due to ice formation and there are no generalized methods to measure Pcpa at subzero temperatures. The present study aims to investigate cell osmotic behavior at subzero temperatures without ice formation. In the study cells were directly injected into super-cooled CPA solutions mounted on a cryomicroscope, and the corresponding osmotic properties were measured. Using ethylene glycol (EG), the value of PEG for mouse (CD-1) metaphase II oocytes at 0, -5, -10 degree C was determined to be 8.451.20, 7.430.91, 6.401.10, x10-6 cm/min, respectively, and EaPEG was calculated to be 3.9 kCal/mol. Lp in the presence of EG (LpEG) at 0, -5, -10 , -15 degree C was determined to be 7.0 1.15, 4.90 1.20, 2.44 0.31, 1.200.24, x 10-2 µm/min/atm, respectively, and EaLp was calculated to be 15.5 kCal/mol. Comparing these values with those previously measured at superzero temperatures, we concluded that for mouse oocytes, the Arrhenius relationship for LpEG is consistent at superzero and subzero temperatures, but the values of PEG at subzero temperatures are much lower than the extrapolated values from the Arrhenius relationship at superzero temperatures, possibly caused by membrane phase transition at low temperatures.

  9. Low temperature synthesis of nanocrystalline magnesium aluminate with high surface area by surfactant assisted precipitation method: Effect of preparation conditions

    Energy Technology Data Exchange (ETDEWEB)

    Mosayebi, Zeinab [Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan (Iran, Islamic Republic of); Rezaei, Mehran, E-mail: rezaei@kashanu.ac.ir [Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan (Iran, Islamic Republic of); Catalyst and Advanced Materials Research Laboratory, Chemical Engineering Department, Faculty of Engineering, University of Kashan, Kashan (Iran, Islamic Republic of); Hadian, Narges [Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan (Iran, Islamic Republic of); Kordshuli, Fazlollah Zareie [Shiraz Petrochemical Co., Shiraz (Iran, Islamic Republic of); Meshkani, Fereshteh [Catalyst and Advanced Materials Research Laboratory, Chemical Engineering Department, Faculty of Engineering, University of Kashan, Kashan (Iran, Islamic Republic of)

    2012-09-15

    Highlights: ► MgAl{sub 2}O{sub 4} showed a high surface area and nanocrystalline structure. ► Addition of polymeric surfactant affected the structural properties of MgAl{sub 2}O{sub 4}. ► MgAl{sub 2}O{sub 4} prepared with surfactant showed a hollow cylindrical shape. -- Abstract: A surfactant assisted co-precipitation method was employed for the low temperature synthesis of magnesium aluminate spinel with nanocrystalline size and high specific surface area. Pluronic P123 triblock copolymer and ammonia solution were used as surfactant and precipitation agent, respectively. The prepared samples were characterized by thermal gravimetric and differential thermal gravimetric analyses (TG/DTG), X-ray diffraction (XRD), N{sub 2} adsorption (BET) and transmission electron microscopy (TEM) techniques. The effects of several process parameters such as refluxing temperature, refluxing time, pH, P123 to metals mole ratio (P123/metals) and calcination temperature on the structural properties of the samples were investigated. The obtained results showed that, among the process parameters pH and refluxing temperature have a significant effect on the structural properties of samples. The results revealed that increase in pH from 9.5 to 11 and refluxing temperature from 40 °C to 80 °C increased the specific surface area of prepared samples in the range of 157–188 m{sup 2} g{sup −1} and 162–184 m{sup 2} g{sup −1}, respectively. The XRD analysis showed the single-phase MgAl{sub 2}O{sub 4} was formed at 700 °C.

  10. Enhancement of structural and magnetic properties of M-type hexaferrite permanent magnet based on synthesis temperature

    Science.gov (United States)

    Anjum, Safia; Sehar, Fatima; Mustafa, Zeeshan; Awan, M. S.

    2018-01-01

    The main purpose of this research work is to develop the single domain magnetic particles of M-type barium hexaferrite (BaFe12O19) using oxide precursors employing conventional powder metallurgy technique. The phase formation and magnetic performance of the powders and magnets will be optimized by adjusting calcination and sintering temperatures. The synthesis of M-type barium hexaferrite was carried out in two sections. A series of four samples have been prepared by initial wet mixed powders calcined at different temperatures, i.e., 750, 850, 950 and 1050 °C. On the basis of structural analysis, the sample calcined at 950 °C has been selected and further divided into four parts to sintered them at 1100, 1150, 1200 and 1250 °C. The structural measurements depict the confirmation of M-type barium hexaferrite structure. SEM micrographs show the hexagonal-shaped grains. The abrupt decrease in coercivity for the sample sintered at 1250 °C has been seen which may be due to high sintering temperature, at which the particles have multi-domain properties.

  11. Low temperature formation of naphthalene and its role in the synthesis of PAHs (Polycyclic Aromatic Hydrocarbons) in the interstellar medium

    Science.gov (United States)

    Zhang, Fangtong; Kim, Y. Seol; Kaiser, Ralf I.; Landera, Alexander; Kislov, Vadim V.; Mebel, Alexander M.; Tielens, A. G. G. M.

    2012-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are regarded as key molecules in the astrochemical evolution of the interstellar medium, but the formation mechanism of even their simplest prototype—naphthalene (C10H8)—has remained an open question. Here, we show in a combined crossed beam and theoretical study that naphthalene can be formed in the gas phase via a barrierless and exoergic reaction between the phenyl radical (C6H5) and vinylacetylene (CH2 = CH-C ≡ CH) involving a van-der-Waals complex and submerged barrier in the entrance channel. Our finding challenges conventional wisdom that PAH-formation only occurs at high temperatures such as in combustion systems and implies that low temperature chemistry can initiate the synthesis of the very first PAH in the interstellar medium. In cold molecular clouds, barrierless phenyl-type radical reactions could propagate the vinylacetylene-mediated formation of PAHs leading to more complex structures like phenanthrene and anthracene at temperatures down to 10 K. PMID:22198769

  12. How PEO-PPO-PEO triblock polymer micelles control the synthesis of gold nanoparticles: temperature and hydrophobic effects.

    Science.gov (United States)

    Khullar, Poonam; Mahal, Aabroo; Singh, Vijender; Banipal, Tarlok Singh; Kaur, Gurinder; Bakshi, Mandeep Singh

    2010-07-06

    Aqueous micellar solutions of F68 (PEO(78)-PPO(30)-PEO(78)) and P103 (PEO(17)-PPO(60)-PEO(17)) triblock polymers were used to synthesize gold (Au) nanoparticles (NPs) at different temperatures. All reactions were monitored with respect to reaction time and temperature by using UV-visible studies to understand the growth kinetics of NPs and the influence of different micellar states on the synthesis of NPs. The shape, size, and locations of NPs in the micellar assemblies were determined with the help of TEM, SEM, and EDS analyses. The results explained that all reactions were carried out with the PEO-PPO-PEO micellar surface cavities present at the micelle-solution interface and were precisely controlled by the micellar assemblies. Marked differences were detected when predominantly hydrophilic F68 and hydrophobic P103 micelles were employed to conduct the reactions. The UV-visible results demonstrated that the reduction of gold ions into nucleating centers was channeled through the ligand-metal charge-transfer complex (LMCT) and carried out by the surface cavities. Excessive hydration of the surface cavities in the case of F68 micelles produced a few small NPs, but their yield and size increased as the micelles were dehydrated under the effect of increasing temperature. The results concluded that the presence of well-defined predominantly hydrophobic micelles with a compact micelle-solution interfacial arrangement of surface cavities ultimately controlled the reaction.

  13. Selective recovery of silver from waste low-temperature co-fired ceramic and valorization through silver nanoparticle synthesis.

    Science.gov (United States)

    Swain, Basudev; Shin, Dongyoon; Joo, So Yeong; Ahn, Nak Kyoon; Lee, Chan Gi; Yoon, Jin-Ho

    2017-11-01

    Considering the value of silver metal and silver nanoparticles, the waste generated during manufacturing of low temperature co-fired ceramic (LTCC) were recycled through the simple yet cost effective process by chemical-metallurgy. Followed by leaching optimization, silver was selectively recovered through precipitation. The precipitated silver chloride was valorized though silver nanoparticle synthesis by a simple one-pot greener synthesis route. Through leaching-precipitation optimization, quantitative selective recovery of silver chloride was achieved, followed by homogeneous pure silver nanoparticle about 100nm size were synthesized. The reported recycling process is a simple process, versatile, easy to implement, requires minimum facilities and no specialty chemicals, through which semiconductor manufacturing industry can treat the waste generated during manufacturing of LTCC and reutilize the valorized silver nanoparticles in manufacturing in a close loop process. Our reported process can address issues like; (i) waste disposal, as well as value-added silver recovery, (ii) brings back the material to production stream and address the circular economy, and (iii) can be part of lower the futuristic carbon economy and cradle-to-cradle technology management, simultaneously. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Bio-synthesis of triangular and hexagonal gold nanoparticles using palm oil fronds’ extracts at room temperature

    Science.gov (United States)

    Usman, Adamu Ibrahim; Aziz, Azlan Abdul; Abu Noqta, Osama

    2018-01-01

    Development of bio-reduction techniques for nanoparticles (NPs) synthesis in medical application remains a challenge to numerous researchers. This work reports a novel technique for the synthesis of triangular and hexagonal gold nanoparticles (AuNP) using palm oil fronds’ (POFs) extracts. The functional groups in the POFs’ extracts operate as a persuasive capping and reducing agent to growth AuNPs. The prepared AuNPs were characterized using UV–vis spectrophotometry, Fourier-transform infrared (FTIR) spectroscopy, dynamic light scattering, energy filtered transmission electron microscopy (EFTEM), and x-ray diffraction (XRD). The analysis of FTIR validates the coating of alkynes and phenolic composites on the AuNPs. This shows a feasible function of biomolecules for efficient stabilization of the AuNPs. EFTEM clearly show the triangular and hexagonal shapes of the prepared AuNPs. The XRD patterns display the peaks of fcc crystal structures at (111), (200), (220), (311) and (222), with average particle sizes of 66.7 and 79.02 nm for 1% and 5% POFs extracts concentrations respectively at room temperature. While at 120 °C the average particles size recorded for 1% and 5% of POFs extract concentrations were 32.17 nm and 45.66 nm respectively, and the reaction completed in less than 2 min. The prepared NPs could be potentially applied in biomedical application, due to their excellent stability and refine morphology without agglomeration.

  15. Facile Synthesis of BiOI Nanoparticles at Room Temperature and Evaluation of their Photoactivity under Sunlight Irradiation.

    Science.gov (United States)

    Mahmoodi, Vahid; Ahmadpour, Ali; Rohani Bastami, Tahereh; Hamed Mousavian, Mohammad Taghi

    2017-08-21

    In this study, highly photoactive BiOI nanoparticles (NPs) under sunlight irradiation were synthesized by a facile precipitation method using polyvinylpyrrolidone (PVP) at room temperature. The as-prepared catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transition electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR) and UV-vis diffuse reflectance spectra (UV-vis DRS). The results of XRD showed that PVP did not have any significant effect on tetragonal crystalline structure of BiOI. Also, using different amounts of PVP in the synthesis led to different morphologies and sizes of BiOI particles. It was found that using 0.2 g of PVP in the synthesis method changed morphology from 1-μm platelets to NPs with size under 10 nm. In addition, the photocatalytic performance of prepared photocatalysts was evaluated in the photodegradation of reactive blue 19 (RB19) dye under sunlight irradiation. The BiOI synthesized using 0.2 g PVP (BiOI0.2) showed higher degradation efficiency compared to BiOI prepared without any additive. Excellent visible light photocatalytic properties of nano-scaled BiOI0.2 samples compared to BiOI platelets could be attributed to higher surface-to-volume ratio and narrow band-gap energy of as-prepared BiOI0.2 NPs. © 2017 The American Society of Photobiology.

  16. High temperature creep properties of directionally solidified CM-247LC Ni-based superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Chiou, Mau-Sheng [Department of Materials Science and Engineering, I-Shou University, Kaohsiung 840, Taiwan (China); Jian, Sheng-Rui, E-mail: srjian@gmail.com [Department of Materials Science and Engineering, I-Shou University, Kaohsiung 840, Taiwan (China); Yeh, An-Chou [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Kuo, Chen-Ming [Department of Mechanical and Automation Engineering, I-Shou University, Kaohsiung 840, Taiwan (China); Juang, Jenh-Yih [Department of Electrophysics, National Chiao Tung University, Hsinchu 300, Taiwan (China)

    2016-02-08

    This study explores the effects of cooling rate after solution heat treatment on the high temperature/low stress (982 °C/200 MPa) creep properties of CM-247LC Nickel base superalloy. Cooling rate was controlled by blowing argon gas, air cooling, and furnace cooling, which, in turn, gave rise to corresponding cooling rates (from 1260 °C to 800 °C) of 18.7, 7.4, and 0.19 °C/s, respectively. The results indicated that higher cooling rate from the solution heat treatment temperature led to finer γ′ precipitates and much improved tertiary creep as well as rupture life time in high-temperature creep test. The microstructural analyses using both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that finer γ′ precipitates and narrower γ channel width could result in denser rafting structure which might have hindered the climb of dislocations across the precipitates rafts.

  17. Methyl Chloride from Direct Methane Partial Oxidation: A High-Temperature Shilov-Like Catalytic System

    Energy Technology Data Exchange (ETDEWEB)

    Yongchun Tang; John (Qisheng) Ma

    2012-03-23

    The intention of this study is to demonstrate and evaluate the scientific and economic feasibility of using special solvents to improve the thermal stability of Pt-catalyst in the Shilov system, such that a high reaction temperature could be achieved. The higher conversion rate (near 100%) of methyl chloride from partial oxidation of methane under the high temperature ({approx} 200 C) without significant Pt0 precipitation has been achieved. High concentration of the Cl- ion has been identified as the key for the stabilization of the Pt-catalysts. H/D exchange measurements indicated that the over oxidation will occur at the elevated temperature, developments of the effective product separation processes will be necessary in order to rationalize the industry-visible CH4 to CH3Cl conversion.

  18. Template-directed synthesis of flexible porphyrin nanocage and nanorings via one-step olefin metathesis.

    Science.gov (United States)

    Zhu, Bin; Chen, Huanxin; Lin, Wei; Ye, Yang; Wu, Jing; Li, Shijun

    2014-10-29

    We describe the fabrication of a suite of flexible porphyrin cages and nanorings from a simple tetraalkene-derived zinc porphyrin monomer via a highly efficient template-directed strategy. The zinc porphyrin monomers were preorganized together by coordination with N atoms of multidentate ligands. Subsequent one-step olefin metathesis furnished a bisporphyrin cage, a triporphyrin nanoring, and a hexaporphyrin nanoring. In the case of the hexaporphyrin nanoring, 24 terminal olefins from six porphyrin monomers reacted with each other to form 12 new double bonds, delivering the final product. The triporphyrin and hexaporphyrin nanorings were further employed as hosts to encapsulate C60 and C70.

  19. Inherently chiral calix[4]arenes via oxazoline directed ortholithiation: synthesis and probe of chiral space.

    Science.gov (United States)

    Herbert, Simon A; van Laeren, Laura J; Castell, Dominic C; Arnott, Gareth E

    2014-01-01

    The diastereoselective oxazoline-directed lithiation of calix[4]arenes is reported with diastereoselective ratios of greater than 100:1 in some instances. Notably, it has been found that the opposite diastereomer can be accessed via this approach merely through the choice of an alkyllithium reagent. The inherently chiral oxazoline calix[4]arenes have also been preliminarily examined as ligands in the palladium-catalyzed Tsuji-Trost allylation reaction, returning results comparable to their planar chiral ferrocene counterparts pointing towards future application of these types of compounds.

  20. Green synthesis of silver nanoparticles using Terminalia cuneata and its catalytic action in reduction of direct yellow-12 dye

    Science.gov (United States)

    Edison, Thomas Nesakumar Jebakumar Immanuel; Lee, Yong Rok; Sethuraman, Mathur Gopalakrishnan

    2016-05-01

    Facile green synthesis of silver nanoparticles (AgNPs) using aqueous bark extract of Terminalia cuneata has been reported in this article. The effects of concentration of the extract, reaction time and pH were studied by UV-Vis spectroscopy. Appearance of yellow color with λmax around ~ 420 nm suggested the formation of AgNPs. The stable AgNPs were further characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), dynamic light scattering (DLS) with zeta potential and high resolution transmission electron microscopy (HR-TEM) with energy dispersive X-ray spectroscopy (EDS) analysis. The synthesized AgNPs were in the size range of 25-50 nm with a distorted spherical shape identified from HR-TEM analysis. The catalytic activity of AgNPs on the reduction of direct yellow-12 using NaBH4 was analyzed using a UV-Vis spectrophotometer. This study showed the efficacy of biogenic AgNPs in catalyzing the reduction of direct yellow-12.

  1. Mutant Hoxd13 induces extra digits in a mouse model of synpolydactyly directly and by decreasing retinoic acid synthesis

    Science.gov (United States)

    Kuss, Pia; Villavicencio-Lorini, Pablo; Witte, Florian; Klose, Joachim; Albrecht, Andrea N.; Seemann, Petra; Hecht, Jochen; Mundlos, Stefan

    2008-01-01

    Individuals with the birth defect synpolydactyly (SPD) have 1 or more digit duplicated and 2 or more digits fused together. One form of SPD is caused by polyalanine expansions in homeobox d13 (Hoxd13). Here we have used the naturally occurring mouse mutant that has the same mutation, the SPD homolog (Spdh) allele, and a similar phenotype, to investigate the molecular pathogenesis of SPD. A transgenic approach and crossing experiments showed that the Spdh allele is a combination of loss and gain of function. Here we identify retinaldehyde dehydrogenase 2 (Raldh2), the rate-limiting enzyme for retinoic acid (RA) synthesis in the limb, as a direct Hoxd13 target and show decreased RA production in limbs from Spdh/Spdh mice. Intrauterine treatment with RA restored pentadactyly in Spdh/Spdh mice. We further show that RA and WT Hoxd13 suppress chondrogenesis in mesenchymal progenitor cells, whereas Hoxd13 encoded by Spdh promotes cartilage formation in primary cells isolated from Spdh/Spdh limbs, and that this was associated with increased expression of Sox6/9. Increased Sox9 expression and ectopic cartilage formation in the interdigital mesenchyme of limbs from Spdh/Spdh mice suggest uncontrolled differentiation of these cells into the chondrocytic lineage. Thus, we propose that mutated Hoxd13 causes polydactyly in SPD by inducing extraneous interdigital chondrogenesis, both directly and indirectly, via a reduction in RA levels. PMID:19075394

  2. The Use of Low Temperature Detectors for Direct Measurements of the Mass of the Electron Neutrino

    Directory of Open Access Journals (Sweden)

    A. Nucciotti

    2016-01-01

    Full Text Available Recent years have witnessed many exciting breakthroughs in neutrino physics. The detection of neutrino oscillations has proved that neutrinos are massive particles, but the assessment of their absolute mass scale is still an outstanding challenge in today particle physics and cosmology. Since low temperature detectors were first proposed for neutrino physics experiments in 1984, there has been tremendous technical progress: today this technique offers the high energy resolution and scalability required to perform competitive experiments challenging the lowest electron neutrino masses. This paper reviews the thirty-year effort aimed at realizing calorimetric measurements with sub-eV neutrino mass sensitivity using low temperature detectors.

  3. Nanoparticles of Sr(OH)2: synthesis in homogeneous phase at low temperature and application for cultural heritage artefacts

    Science.gov (United States)

    Ciliberto, E.; Condorelli, G. G.; La Delfa, S.; Viscuso, E.

    2008-07-01

    This paper concerns the synthesis and the characterization of nanometer particles of Sr(OH)2, a moderately high water soluble hydroxide (Ksp= 3.2×10-4 at 25 °C). The reported process yields strontium hydroxide nanoparticles starting from low cost raw materials in aqueous medium (homogeneous phase) at low temperature (below 100 °C) by chemical precipitation from salt solutions, involving very simple operational steps and avoiding the use of organic solvents. Observations by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron dispersive X-Ray (EDX) and Fourier transform infrared spectroscopy (FTIR) indicate that the particles are well-crystallized and have nanometer dimensions (˜ 30 nm in diameter). Moreover, experimental evidence shows the potential use of this material for the protection and the consolidation of wall paintings (frescoes), paper, stone, wood and other artistic artefacts.

  4. Effect of pretreatment temperature on catalytic performance of the catalysts derived from cobalt carbonyl cluster in Fischer-Tropsch Synthesis

    Directory of Open Access Journals (Sweden)

    Byambasuren O

    2017-02-01

    Full Text Available The monometallic cobalt-based catalysts were prepared by pretreating the catalysts derived from carbonyl cluster precursor (CO6Co2CC(COOH2 supported on γ-Al2O3 with hydrogen at 180, 220, and 260°C respectively. The temperature effect of the pretreatments on the structure evolution of cluster precursors and the catalytic performance of the Fischer-Tropsch (F-T synthesis was investigated. The pretreated catalyst at 220°C with unique phase structure exhibited best catalytic activity and selectivity among three pretreated catalysts. Moreover, the catalysts exhibited high dispersion due to the formation of hydrogen bonds between the cluster precursor and γ-Al2O3 support.

  5. Effect of Synthesis Temperature, Nucleation Time, and Postsynthesis Heat Treatment of ZnO Nanoparticles and Its Sensing Properties

    Directory of Open Access Journals (Sweden)

    Umair Manzoor

    2015-01-01

    Full Text Available Control in size, crystallinity, and optical properties of ZnO nanoparticles (NPs synthesized via coprecipitate method were investigated. A systematic change in particle size, crystallinity, and optical properties was observed by increasing synthesis temperature from 65°C to 75°C. A detailed study also suggested that smaller nucleation time is better to control the size distribution but the crystallinity will be compromised accordingly. Postannealing of ZnO NPs at 400°C also improves the crystal quality. Ultraviolet (UV sensors were successfully synthesized and the results suggested that as-synthesized ZnO NPs can be used as active material for sensor applications.

  6. The Effect of the Rolling Direction, Temperature, and Etching Time on the Photochemical Machining of Monel 400 Microchannels

    Directory of Open Access Journals (Sweden)

    Deepakkumar H. Patil

    2016-01-01

    Full Text Available The present paper describes the effect of the rolling direction on the quality of microchannels manufactured using photochemical machining (PCM of Monel 400. Experiments were carried out to fabricate microchannels along and across the rolling direction to investigate the effect of the grain orientation on microchannel etching. The input parameters considered were channel width and rolling direction, whereas the depth of etch was the response parameters. Different channels of widths of 60, 100, 150, 200, and 250 μm were etched. The effects of the etching time and temperature of the etchant solution on the undercut and depth of the microchannels were studied. For good quality microchannels, the effects of spinning time, spinning speed, exposure time, and photoresist film strength were also taken into consideration. Optimized values of the above were used for the experimentation. The results show that the depth of etch of the microchannel increases more along the rolling direction than across the rolling direction. The channel width and depth are significantly affected by the etching time and temperature. The proposed study reports an improvement in the quality of microchannels produced using PCM.

  7. Synthesis, characterization and analysis of platinum-based multiphase catalysts for direct ethanol fuel cells

    Science.gov (United States)

    Mann, Jonathan R.

    Platinum-based particles are synthesized via the polyol process in an effort to include various metal oxides in a multi-phase catalyst for the direct ethanol fuel cell anode. Among Eu, In, La and Nb, no single metal oxide with platinum yields open circuit potentials or maximum current densities as high as tin oxide with platinum. For this reason, particles with platinum, tin oxide and the oxide of a third metal were developed. Platinum tin/indium oxide slightly outperforms platinum tin oxide. The particles are characterized by TEM, EDX, XRD and ICP. The metal oxides and the platinum are located together in one particle, uniformly 5.3 nm in diameter. ICP analysis indicates that the catalysts are 20% platinum on carbon and the metals of the oxides are on the order of 1-2% by mass. The catalytic abilities of the particles were evaluated in a single cell direct ethanol fuel cell where polarization curves were taken up to 130°C, and oxidation products were analyzed by gas chromatography. Open circuit voltages of as high as 0.82 V were obtained for platinum tin/indium oxide catalysts and current densities as high as 0.4 A cm-2 were seen. The cells produced large amounts of acetaldehyde and acetic acid, as well as small amounts of methanol and carbon dioxide. A spillover mechanism is proposed for the oxidation of ethanol to CO2 on these platinum/metal oxide catalysts.

  8. Ionic liquid-assisted direct synthesis of PdO nanoparticles immobilized on boehmite nanoparticles.

    Science.gov (United States)

    Cho, Sung Dae; Park, HoSeok

    2011-05-01

    We demonstrated a simple route to simultaneously synthesize PdO and boehmite nanoparticles, and to directly immobilize the former on the latter using an ionic liquid (IL)-assisted one-pot solution method. PdO nanoparticles were directly immobilized on boehmite nanoparticles, and their amount and distribution were controlled by the stoichiometry of the mixture. In particular, γ-alumina nanofibers, which were topochemically transformed from boehmites, exhibited lengths of ca. 40-70 nm and diameters of ca. 1.5-3 nm, while PdO nanoparticles had diameters of ca. 2-4 nm. The nanocrystalline structures of the PdO nanoparticles immobilized on the boehmite nanoparticles were characterized by high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), and (27)Al nuclear magnetic resonance (NMR). The one-step synthetic method described herein allows for the design and fabrication of host-guest systems of inorganic or metallic nanomaterials with hetero-nanostructures. Copyright © 2011 Elsevier Inc. All rights reserved.

  9. Direct ethanol production from cellulosic materials at high temperature using the thermotolerant yeast Kluyveromyces marxianus displaying cellulolytic enzymes

    Energy Technology Data Exchange (ETDEWEB)

    Yanase, Shuhei; Yamada, Ryosuke; Ogino, Chiaki; Kondo, Akihiko [Kobe Univ. (Japan). Dept. of Chemical Science and Engineering; Hasunuma, Tomohisa; Tanaka, Tsutomu; Fukuda, Hideki [Kobe Univ. (Japan). Organization of Advanced Science and Technology

    2010-09-15

    To exploit cellulosic materials for fuel ethanol production, a microorganism capable of high temperature and simultaneous saccharification-fermentation has been required. However, a major drawback is the optimum temperature for the saccharification and fermentation. Most ethanol-fermenting microbes have an optimum temperature for ethanol fermentation ranging between 28 C and 37 C, while the activity of cellulolytic enzymes is highest at around 50 C and significantly decreases with a decrease in temperature. Therefore, in the present study, a thermotolerant yeast, Kluyveromyces marxianus, which has high growth and fermentation at elevated temperatures, was used as a producer of ethanol from cellulose. The strain was genetically engineered to display Trichoderma reesei endoglucanase and Aspergillus aculeatus {beta}-glucosidase on the cell surface, which successfully converts a cellulosic {beta}-glucan to ethanol directly at 48 C with a yield of 4.24 g/l from 10 g/l within 12 h. The yield (in grams of ethanol produced per gram of {beta}-glucan consumed) was 0.47 g/g, which corresponds to 92.2% of the theoretical yield. This indicates that high-temperature cellulose fermentation to ethanol can be efficiently accomplished using a recombinant K. marxianus strain displaying thermostable cellulolytic enzymes on the cell surface. (orig.)

  10. Effect of Growth Rate on Elevated Temperature Plastic Flow and Room Temperature Fracture Toughness of Directionally Solidified NiAl-31Cr-3Mo

    Science.gov (United States)

    Whittenberger, J. Daniel; Raj, S. V.; Locci, I. E.; Salem, J. A.

    1999-01-01

    The eutectic system Ni-33Al-31Cr-3Mo was directionally solidified at rates ranging from 7.6 to 508 mm/h. Samples were examined for microstructure and alloy chemistry, compression tested at 1200 and 1300 K, and subjected to room temperature fracture toughness measurements. Lamellar eutectic grains were formed at 12.7 mm/h; however cellular structures with a radial eutectic pattern developed at faster growth rates. Elevated temperature compression testing between 10(exp -4) to 10(exp -7)/s did not reveal an optimum growth condition, nor did any single growth condition result in a significant fracture toughness advantage. The mechanical behavior, taken together, suggests that Ni-33Al-31Cr-3Mo grown at rates from 25.4 to 254 mm/h will have nominally equivalent properties.

  11. Reactive temperature and growth time effects on the morphology of PMN–PT nanorods by hydrothermal synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Luo, W.B., E-mail: luowb@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); He, K. [School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Xu, D., E-mail: frank@shu.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Li, C.; Bai, X.Y. [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Shuai, Y.; Wu, C.G.; Zhang, W.L. [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Collaboration Innovation Center of Electronic Materials and Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2016-06-25

    Single crystalline nanorod (Nr) is considered to be a promising candidate in many nano-electric devices due to its excellent electric properties. Here we report a method to fabricate 0.65(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}–0.35PbTiO{sub 3} (PMN–PT) single crystalline Nr by controlling the hydrothermal synthesis temperature and reactive time. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) have been employed to investigate the morphology and crystal characteristics of the PMN–PT Nrs. It was confirmed that single crystalline PMN–PT Nrs have been fabricated under optimal synthesis condition. Finally, the ferroelectric properties of PMN–PT Nrs were measured, and the coercive field, remnant polarization and spontaneous polarization of the nanorods are 2.78 kV/mm, 17.08 μC/cm{sup 2} and 31.25 μC/cm{sup 2} respectively. - Highlights: • 0.65(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}–0.35PbTiO{sub 3} (PMN–PT) nanorods were prepared by the hydrothermal method. • The hydrothermal temperature and reaction time have importance influence on the morphology of PMN–PT Nanorods. • The coercive field, remnant polarization and spontaneous polarization of PMN–PT Nrs are: 2.78 kV/mm, 17.08 μc/cm{sup 2} and 31.25 μc/cm{sup 2}.

  12. Synthesis of long alkyl chain ethers through direct etherification of biomass-based alcohols with 1-octene over heterogeneous acid catalysts

    NARCIS (Netherlands)

    Ruppert, A.M.; Parvulescu, A.N.; Arias, M.J.; Bruijnincx, P.C.A.; Klein Gebbink, R.J.M.; Weckhuysen, B.M.

    2009-01-01

    Heterogeneous etherification of various biomass-based alcohols with 1-octene was investigated as a direct route for the synthesis of long alkyl chain ethers. Several acid catalyst materials including Amberlyst resins and various zeolites were screened as etherification catalysts in a solventless

  13. Total synthesis of cis-Hydroazulene sesquiterpenes : base-induced and -directed elimination and rearrangement reactions of perhydronaphthalene-1,4-diol monosulfonate esters

    NARCIS (Netherlands)

    Jenniskens, L.H.D.

    1992-01-01

    The total synthesis of a number of cis-fused hydroazulene sesquiterpenes is described in this thesis. In this synthetic study, ample attention is paid to the mechanistic aspects of the base- induced and -directed rearrangement and elimination reactions of perhydronaphthalene-1,4-diol

  14. Body temperature predicts the direction of internal desynchronization in humans isolated from time cues

    NARCIS (Netherlands)

    Daan, Serge; Honma, Sato; Honma, Ken-ichi

    2013-01-01

    This publication presents a new analysis of experiments that were carried out in human subjects in isolation from time cues, under supervision of Jurgen Aschoff and Rutger Wever at the Max Planck Institute for Behavioural Physiology (Erling-Andechs, Germany, 1964-1974). Mean rectal temperatures

  15. The theory, direction, and magnitude of ecosystem fire probability as constrained by precipitation and temperature.

    Science.gov (United States)

    Guyette, Richard; Stambaugh, Michael C; Dey, Daniel; Muzika, Rose Marie

    2017-01-01

    The effects of climate on wildland fire confronts society across a range of different ecosystems. Water and temperature affect the combustion dynamics, irrespective of whether those are associated with carbon fueled motors or ecosystems, but through different chemical, physical, and biological processes. We use an ecosystem combustion equation developed with the physical chemistry of atmospheric variables to estimate and simulate fire probability and mean fire interval (MFI). The calibration of ecosystem fire probability with basic combustion chemistry and physics offers a quantitative method to address wildland fire in addition to the well-studied forcing factors such as topography, ignition, and vegetation. We develop a graphic analysis tool for estimating climate forced fire probability with temperature and precipitation based on an empirical assessment of combustion theory and fire prediction in ecosystems. Climate-affected fire probability for any period, past or future, is estimated with given temperature and precipitation. A graphic analyses of wildland fire dynamics driven by climate supports a dialectic in hydrologic processes that affect ecosystem combustion: 1) the water needed by plants to produce carbon bonds (fuel) and 2) the inhibition of successful reactant collisions by water molecules (humidity and fuel moisture). These two postulates enable a classification scheme for ecosystems into three or more climate categories using their position relative to change points defined by precipitation in combustion dynamics equations. Three classifications of combustion dynamics in ecosystems fire probability include: 1) precipitation insensitive, 2) precipitation unstable, and 3) precipitation sensitive. All three classifications interact in different ways with variable levels of temperature.

  16. Enrichment of denitrifying methanotrophic bacteria for application after direct low-temperature anaerobic sewage treatment

    NARCIS (Netherlands)

    Kampman, C.; Hendrickx, T.L.G.; Luesken, F.; Alen, T.A.; Jetten, M.S.M.; Camp, op den H.J.M.; Zeeman, G.; Buisman, C.J.N.; Temmink, B.G.

    2012-01-01

    Despite many advantages of anaerobic sewage treatment over conventional activated sludge treatment, it has not yet been applied in temperate zones. This is especially because effluent from low-temperature anaerobic treatment contains nitrogen and dissolved methane. The presence of nitrogen and

  17. Measuring Air Temperature in Glazed Ventilated Facades in the Presence of Direct Solar Radiation

    DEFF Research Database (Denmark)

    Kalyanova, Olena; Zanghirella, Fabio; Heiselberg, Per

    2007-01-01

    A distinctive element of buildings with a double glazed façade is naturally or mechanically driven flow in a ventilated cavity. Accurate air temperature measurements in the cavity are crucial to evaluate the dynamic performance of the façade, to predict and control its behavior as a significant p...

  18. The theory, direction, and magnitude of ecosystem fire probability as constrained by precipitation and temperature

    Science.gov (United States)

    Richard Guyette; Michael C. Stambaugh; Daniel Dey; Rose Marie Muzika; Ben Bond-Lamberty

    2017-01-01

    The effects of climate on wildland fire confronts society across a range of different ecosystems. Water and temperature affect the combustion dynamics, irrespective of whether those are associated with carbon fueled motors or ecosystems, but through different chemical, physical, and biological processes. We use an ecosystem combustion equation developed with the...

  19. Direct Evidence for Solid-like Hydrogen in a Nanoporous Carbon Hydrogen Storage Material at Supercritical Temperatures.

    Science.gov (United States)

    Ting, Valeska P; Ramirez-Cuesta, Anibal J; Bimbo, Nuno; Sharpe, Jessica E; Noguera-Diaz, Antonio; Presser, Volker; Rudic, Svemir; Mays, Timothy J

    2015-08-25

    Here we report direct physical evidence that confinement of molecular hydrogen (H2) in an optimized nanoporous carbon results in accumulation of hydrogen with characteristics commensurate with solid H2 at temperatures up to 67 K above the liquid-vapor critical temperature of bulk H2. This extreme densification is attributed to confinement of H2 molecules in the optimally sized micropores, and occurs at pressures as low as 0.02 MPa. The quantities of contained, solid-like H2 increased with pressure and were directly evaluated using in situ inelastic neutron scattering and confirmed by analysis of gas sorption isotherms. The demonstration of the existence of solid-like H2 challenges the existing assumption that supercritical hydrogen confined in nanopores has an upper limit of liquid H2 density. Thus, this insight offers opportunities for the development of more accurate models for the evaluation and design of nanoporous materials for high capacity adsorptive hydrogen storage.

  20. Open-cycle magnetohydrodynamic power plant based upon direct-contact closed-loop high-temperature heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Berry, Gregory F. (Naperville, IL); Minkov, Vladimir (Skokie, IL); Petrick, Michael (Joliet, IL)

    1988-01-01

    A magnetohydrodynamic (MHD) power generating system in which ionized combustion gases with slag and seed are discharged from an MHD combustor and pressurized high temperature inlet air is introduced into the combustor for supporting fuel combustion at high temperatures necessary to ionize the combustion gases, and including a heat exchanger in the form of a continuous loop with a circulating heat transfer liquid such as copper oxide. The heat exchanger has an upper horizontal channel for providing direct contact between the heat transfer liquid and the combustion gases to cool the gases and condense the slag which thereupon floats on the heat transfer liquid and can be removed from the channel, and a lower horizontal channel for providing direct contact between the heat transfer liquid and pressurized air for preheating the inlet air. The system further includes a seed separator downstream of the heat exchanger.

  1. Open-cycle magnetohydrodynamic power plant based upon direct-contact closed-loop high-temperature heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Berry, Gregory F.; Minkov, Vladimir; Petrick, Michael

    1988-01-05

    A magnetohydrodynamic (MHD) power generating system in which ionized combustion gases with slag and seed are discharged from an MHD combustor and pressurized high temperature inlet air is introduced into the combustor for supporting fuel combustion at high temperatures necessary to ionize the combustion gases, and including a heat exchanger in the form of a continuous loop with a circulating heat transfer liquid such as copper oxide. The heat exchanger has an upper horizontal channel for providing direct contact between the heat transfer liquid and the combustion gases to cool the gases and condense the slag which thereupon floats on the heat transfer liquid and can be removed from the channel, and a lower horizontal channel for providing direct contact between the heat transfer liquid and pressurized air for preheating the inlet air. The system further includes a seed separator downstream of the heat exchanger.

  2. Direct synthesis of RGO/Cu{sub 2}O composite films on Cu foil for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Xiangmao; Wang, Kun [Key Laboratory for Ultrafine Materials of the Ministry of Education, Shanghai Key Laboratory of Advanced Polymeric Materials, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Zhao, Chongjun, E-mail: chongjunzhao@ecust.edu.cn [Key Laboratory for Ultrafine Materials of the Ministry of Education, Shanghai Key Laboratory of Advanced Polymeric Materials, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong 2500 (Australia); Qian, Xiuzhen [Key Laboratory for Ultrafine Materials of the Ministry of Education, Shanghai Key Laboratory of Advanced Polymeric Materials, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Chen, Shi [School of Information Engineering, Wuhan University of Technology, Wuhan 430070 (China); Li, Zhen, E-mail: zhenl@uow.edu.au [Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong 2500 (Australia); Liu, Huakun; Dou, Shixue [Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong 2500 (Australia)

    2014-02-15

    Graphical abstract: RGO/Cu{sub 2}O/Cu composites were synthesized by simple hydrothermal treatment of copper foils with graphene oxide, in which the reduction of graphene oxide and the formation of Cu{sub 2}O nanoparticles simultaneously happened in one-pot reaction. These composites can be directly used as electrodes of supercapacitors with the highest specific capacitance of 98.5 F/g at 1 A g{sup −1}, which is much better than that of CuO or Cu{sub 2}O electrodes. -- Highlights: • The RGO/Cu{sub 2}O/Cu composites were obtained by a friendly method in one step. • Improved capacitance performance is realized by the hydrothermal treatment of graphene oxides with Cu foils. • RGO/Cu{sub 2}O/Cu-200 composites exhibit the largest specific capacitance of 98.5 F g{sup −1} at 1 A g{sup −1}. -- Abstract: Reduced graphene oxide/cuprous oxide (RGO/Cu{sub 2}O) composite films were directly synthesized on the surface of copper foil substrates through a straight redox reaction between GO and Cu foil via a hydrothermal approach. Characterization of the resultant composites with X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and field emission scanning electron microscope (FESEM) confirms the formation of Cu{sub 2}O and reduction of GO, in which Cu{sub 2}O nanoparticles were well covered by RGO. The resultant composites (referred to as RGO/Cu{sub 2}O/Cu) were directly used as electrodes for supercapacitors, and their electrochemical performance was assessed by cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectrometry (EIS) in 1 M KOH aqueous solution. A specific capacitance of 98.5 F g{sup −1} at 1 A g{sup −1} was obtained, which is much higher than that of pure Cu{sub 2}O prepared under the same conditions, due to the presence of RGO.

  3. Direct and indirect inhibition of single leaf respiration by elevated CO[sub 2] concentrations; Interaction with temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ziska, L.H.; Bunce, J.A. (Climate Stress Laboratory, USDA-ARS, Beltsville Agricultural Research Center, Beltsville, MD (United States))

    1994-01-01

    Two herbaceous perennials, alfalfa (Medicago sativa L. cv. Arc) and orchard grass (Dactylus glomerata L. cv. Potomac), were grown at ambient (367 [mu]mol mol[sup -1]) and elevated (729 [mu]mol mol[sup -1]). CO[sub 2] concentrations at constant temperatures of 15, 20, 25 and 30 dg. C in order to examine direct and indirect changes in nighttime CO[sub 2] efflux rate (respiration) of single leaves. Direct (biochemical) effects of CO[sub 2] on nighttime respiration were determined for each growth condition by brief (<30 min) exposure to each CO[sub 2] concentration. If no direct inhibition of respiration was observed, then long-term reductions in CO-2 efflux between CO[sub 2] treatments were presumed to be due to indirect inhibition, probably related to long-term changes in leaf composition. By this criterion, indirect effects of CO[sub 2] on leaf respiration were observed at 15 and 20 deg. C for M. sativa on a weight basis, but not on a leaf area or protein basis. Direct effects however, were observed at 15, 20 and 25 deg. C in D. glomerata; therefore the observed reductions in respiration for leaves grown and measured at elevated relative to ambient CO[sub 2] concentrations could not be distinguished as indirect inhibition. No inhibition of respiration at elevated CO[sub 2] was observed at the highest growth temperature (30 deg. C) in either species. CO[sub 2] efflux increased with measurement and growth temperature for M. sativa at both CO[sub 2] concentrations; however, CO[sub 2] efflux in D. glomerata showed complete acclimation to growth temperature. Stimulation of leaf area and weight by elevated CO[sub 2] levels declined with growth temperature in both species. Data from the present study suggest that both direct and indirect inhibition of respiration are possible with future increases in atmospheric CO[sub 2], and that the degree of each type of respiratory inhibition is a function of growth temperature. (au) (25 refs.)

  4. Zeolites synthesis using 1,6-diaminohexane as a structure directing agent

    Science.gov (United States)

    Dari, Djamal; Djafri, Fatiha; Bengueddach, Abdelkader

    2017-09-01

    Mordenite (MOR structure), ZSM-5 and silicalite-1(MFI structure) zeolites have been synthetized by hydrothermal method using 1,6-diaminohexane (DAH) as a structure directing agent. From the characterization of the synthesized materials, it could be deduced that the organic compound acts as a pore-filling in the crystallization of ZSM-5 and Silicalite-1, however the amount of 1,6-diaminohexane incorporated in the mordenite zeolite is low. The effect of alkaline cation shows that sodium and potasium are essential factors governing the crystallization of MOR and MFI zeolites. Pure silicalite-1 zeolite can be obtained in the presence of sodium as well as in the presence of potasium, whereas, mordenite and pure ZSM-5 zeolites can not be synthesized in the absence of sodium.

  5. Starch-directed green synthesis, characterization and morphology of silver nanoparticles.

    Science.gov (United States)

    Khan, Zaheer; Singh, Taruna; Hussain, Javed Ijaz; Obaid, Abdullah Yousif; Al-Thabaiti, Shaeel Ahmed; El-Mossalamy, E H

    2013-02-01

    Silver nanoparticles were prepared by a simple chemical reduction method using ascorbic acid and starch as reducing and stabilizing agents, respectively. The effect of starch, silver ions and ascorbic acid was studied on the morphology of the silver nano-particles using UV-visible spectrophotometry. The initial reaction time min and amount of starch were important parameters for the growth of Ag-nanoparticles. The morphology was evaluated from transmission electron microscopy (TEM). The truncated triangle nano-plates (from 17 to 30 nm), polyhedron, spherical with some irregular shaped Ag-nanoparticles were formed in presence of starch. Particles are aggregated in an irregular manner, leads to the formation of butterfly-like structures of silver. Starch acts as a stabilizing, shape-directing and capping agent during the growth processes. Silver nanoparticles adsorbed electrostatically on the outer OH groups of amylose left-handed helical conformation in solution. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. Formation of alloys in Ti-V system in hydride cycle and synthesis of their hydrides in self-propagating high-temperature synthesis regime

    Energy Technology Data Exchange (ETDEWEB)

    Aleksanyan, A.G., E-mail: a.g.aleks_yan@mail.ru [A.B. Nalbandyan Institute of Chemical Physics of Armenian NAS, 5/2 P.Sevak Str., Yerevan 0014 (Armenia); Dolukhanyan, S.K. [A.B. Nalbandyan Institute of Chemical Physics of Armenian NAS, 5/2 P.Sevak Str., Yerevan 0014 (Armenia); Shekhtman, V.Sh. [Institute of Solid State Physics, RAS, Chernogolovka, Moscow District 142432 (Russian Federation); Huot, J., E-mail: jacques_huot@uqtr.ca [Institut de recherche sur l' hydrogene, Universite du Quebec a Trois-Rivieres (Canada); Ter-Galstyan, O.P.; Mnatsakanyan, N.L. [A.B. Nalbandyan Institute of Chemical Physics of Armenian NAS, 5/2 P.Sevak Str., Yerevan 0014 (Armenia)

    2011-09-15

    Research highlights: > We synthesize Ti-V alloys by new 'hydride cycle' method. Structural characteristics of formed alloys we investigate by X-ray diffraction. > We show that the alloys contain mainly BCC crystal structure. > We investigate the interaction of the synthesized alloys with hydrogen in combustion regime. > We study the properties of hydrides by X-ray, DTA and DSC analyses. - Abstract: In the present work, the possibility of formation of titanium and vanadium based alloys of BCC structure using hydride cycle was investigated. The mechanism of formation of alloys in Ti-V system from the powders of hydrides TiH{sub 2} and VH{sub 0.9} (or of V) by compaction followed by dehydrogenation was studied. Then, the interaction of the synthesized alloys with hydrogen in combustion regime (self-propagating high-temperature synthesis, SHS) resulting in hydrides of these alloys was investigated. DTA and DSC analyses of some alloys and their hydrides were performed and their thermal characteristics were measured.

  7. Impacts of interactive dust and its direct radiative forcing on interannual variations of temperature and precipitation in winter over East Asia: Impacts of Dust on IAVs of Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Lou, Sijia [Scripps Institution of Oceanography, University of California, San Diego, La Jolla California USA; Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA; Russell, Lynn M. [Scripps Institution of Oceanography, University of California, San Diego, La Jolla California USA; Yang, Yang [Scripps Institution of Oceanography, University of California, San Diego, La Jolla California USA; Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA; Liu, Ying [Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA; Singh, Balwinder [Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA; Ghan, Steven J. [Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA

    2017-08-24

    We used 150-year pre-industrial simulations of the Community Earth System Model (CESM) to quantify the impacts of interactively-modeled dust emissions on the interannual variations of temperature and precipitation over East Asia during the East Asian Winter Monsoon (EAWM) season. The simulated December-January-February dust column burden and dust optical depth are lower over northern China in the strongest EAWM years than those of the weakest years, with regional mean values lower by 38.3% and 37.2%, respectively. The decrease in dust over the dust source regions (the Taklamakan and Gobi Deserts) and the downwind region (such as the North China Plain) leads to an increase in direct radiative forcing (RF) both at the surface and top of atmosphere by up to 1.5 and 0.75 W m-2, respectively. The effects of EAWM-related variations in surface winds, precipitation and their effects on dust emissions and wet removal contribute about 67% to the total dust-induced variations of direct RF at the surface and partly offset the cooling that occurs with the EAWM strengthening by heating the surface. The variations of surface air temperature induced by the changes in wind and dust emissions increase by 0.4-0.6 K over eastern coastal China, northeastern China, and Japan, which weakens the impact of EAWM on surface air temperature by 3–18% in these regions. The warming results from the combined effects of changes in direct RF and easterly wind anomalies that bring warm air from the ocean to these regions. Moreover, the feedback of the changes in wind on dust emissions weakens the variations of the sea level pressure gradient on the Siberian High while enhancing the Maritime Continent Low. Therefore, cold air is prevented from being transported from Siberia, Kazakhstan, western and central China to the western Pacific Ocean and decreases surface air temperature by 0.6 K and 2 K over central China and the Tibetan Plateau, respectively. Over eastern coastal China, the variations of

  8. Origin of low temperature deactivation of Ni5Ga3 nanoparticles as catalyst for methanol synthesis

    DEFF Research Database (Denmark)

    Gardini, Diego; Sharafutdinov, Irek; Damsgaard, Christian Danvad

    In an effort to find alternative energy sources capable to compete with fossil fuels, methanol synthesis could represent a realistic solution to store “green” hydrogen produced from electrolysis or photo-induced water splitting. Recently, density functional theory (DFT) calculations [1] proposed Ni......-Ga alloys as active catalysts for methanol production from syngas mixtures and Ni-Ga nanoparticles supported on highly porous silica have been prepared using an incipient wetness impregnation technique from a solution of nickel and gallium nitrates [2]. Tests conducted in a fixed-bed reactor showed...... that the highest methanol yield is obtained with a Ni5Ga3 alloy exposed to a 25% CO2 – 75% H2 reaction mixture at 210 °C [2]. Under these experimental conditions, the catalyst is found to lose 35% of its activity after 20 hours of continuous testing at both 1 and 5 Bars. Although in situ XRD and EXAFS studies [3...

  9. Low-temperature synthesis of CuO-interlaced nanodiscs for lithium ion battery electrodes

    Directory of Open Access Journals (Sweden)

    Seo Seung-Deok

    2011-01-01

    Full Text Available Abstract In this study, we report the high-yield synthesis of 2-dimensional cupric oxide (CuO nanodiscs through dehydrogenation of 1-dimensional Cu(OH2 nanowires at 60°C. Most of the nanodiscs had a diameter of approximately 500 nm and a thickness of approximately 50 nm. After further prolonged reaction times, secondary irregular nanodiscs gradually grew vertically into regular nanodiscs. These CuO nanostructures were characterized using X-ray diffraction, transmission electron microscopy, and Brunauer-Emmett-Teller measurements. The possible growth mechanism of the interlaced disc CuO nanostructures is systematically discussed. The electrochemical performances of the CuO nanodisc electrodes were evaluated in detail using cyclic voltammetry and galvanostatic cycling. Furthermore, we demonstrate that the incorporation of multiwalled carbon nanotubes enables the enhanced reversible capacities and capacity retention of CuO nanodisc electrodes on cycling by offering more efficient electron transport paths.

  10. Temperature Distribution and Thermal Deformation of the Crystallization Roller Based on the Direct Thermal-Structural Coupling Method

    Science.gov (United States)

    Pan, Liping; He, Zhu; Li, Baokuan; Zhou, Kun; Sun, Ke

    2017-03-01

    The temperature distribution and the thermal deformation of the crystallization roller have a significant effect on the forming process of the thin steel strip. Finite element analysis has been used to simulate the temperature distribution and the thermal deformation in a crystallization roller through the direct thermal-structural coupling analysis method. Various parameters, such as different rotational velocities, diverse locations of cooling water pipes, and typical velocities of cooling water have been systematically investigated. It is found that the temperature and the equivalent stress of the outer surface reach the steady state after 30 s of rotations, and they are influenced remarkably by the factors of rotational velocity and cooling water pipe depth. Meanwhile, the radial displacement approaches the steady state after 300 s of revolutions and is significantly affected by the cooling water velocity.

  11. Spectroscopic investigation on the chemical forms of Cu during the synthesis of zeolite X at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Terzano, Roberto [Dipartimento di Biologia e Chimica Agro-forestale ed Ambientale, Universita degli Studi di Bari, Via Amendola 165/A, I-70126 Bari (Italy)]. E-mail: r.terzano@agr.uniba.it; Spagnuolo, Matteo [Dipartimento di Biologia e Chimica Agro-forestale ed Ambientale, Universita degli Studi di Bari, Via Amendola 165/A, I-70126 Bari (Italy); Medici, Luca [Istituto di Metodologie per l' Analisi Ambientale (I.M.A.A.), C.N.R, Contrada S. Loja, I-85050 Tito Scalo, Potenza (Italy); Tateo, Fabio [Istituto di Geoscienze e Georisorse (I.G.G.), C.N.R., Sezione di Padova, c/o Dipartimento di Geologia, Paleontologia e Geofisica, Universita degli Studi di Padova, Via Giotto 1, I-35137 Padova (Italy); Vekemans, Bart [Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610, Wilrijk (Belgium); Janssens, Koen [Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610, Wilrijk (Belgium); Ruggiero, Pacifico [Dipartimento di Biologia e Chimica Agro-forestale ed Ambientale, Universita degli Studi di Bari, Via Amendola 165/A, I-70126 Bari (Italy)

    2006-06-15

    The direct synthesis of zeolites in polluted soils has proved to be a promising process for the stabilization of metals inside these minerals. Nevertheless, more detailed information about this process is still needed in order to better foresee the fate of metals in treated soils. In this work, zeolite X has been synthesized under alkaline conditions in an aqueous solution containing 2500 mg kg{sup -1} of Cu, starting from Na silicate and Al hydroxide at 60 deg. C. Aluminium, Si and Cu concentrations in the aqueous phase, during zeolite synthesis, were measured over a period of 160 h. The solid products have been characterized over time by XRD, SEM-EDX, ESR, FT-IR, and synchrotron radiation X-ray microbeam absorption near edge structure ({mu}-XANES) and extended X-ray absorption fine structure ({mu}-EXAFS) spectroscopy. It appears that the marked reduction of Cu concentration in solution is not only due to a simple precipitation effect, but also to processes connected with the formation of zeolite X which could entrap, inside its porous structure, nano- or micro-occlusions of precipitated Cu hydroxides and/or oxides. In addition, EXAFS observations strengthen the hypothesis of the presence of different Cu phases even at a short-range molecular level and suggest that some of these occlusions could be even bound to the zeolite framework. The results suggest that zeolite formation could be used to reduce the availability of metals in polluted soils.

  12. Large-Scale Synthesis of Silver Nanoparticles by Aqueous Reduction for Low-Temperature Sintering Bonding

    Directory of Open Access Journals (Sweden)

    Qiu Xiliang

    2014-01-01

    Full Text Available Silver nanoparticles with average diameter of 22.4 nm were prepared by aqueous reduction method for low-temperature sintering bonding application. The reaction temperature and PVP concentration, which are the influential factors of nanoparticle characteristics, were investigated during reduction process. In our research, monodispersity of nanoparticles was remarkably improved while unfavorable agglomeration was avoided with the AgNO3/PVP mass ratio of 1 : 4 at the reaction temperature 30°C. Besides, copper pads were successfully bonded using sintering paste employing fresh silver nanoparticles with diameter of 20~35 nm at 200°C. In addition, after morphology of the bonding joint was analysed by scanning electron microscope (SEM, the porous sintering characteristics were confirmed.

  13. Temperature dependence of the direct piezoelectric effect in relaxor-ferroelectric single crystals: Intrinsic and extrinsic contributions

    Science.gov (United States)

    Davis, Matthew; Damjanovic, Dragan; Setter, Nava

    2006-10-01

    The direct piezoelectric response d33 of [001]C-poled 0.955Pb(Zn1/3Nb2/3)O3-0.045PbTiO3 [PZN-4.5PT] and 0.98Pb(Zn1/3Nb2/3)O3-0.08PbTiO3 [PZN-8PT] has been investigated as a function of temperature upon heating above 40°C to the paraelectric phase. Using a Rayleigh-law based analysis, it is shown that both the reversible/intrinsic and irreversible (extrinsic) contributions to the response increase in both compositions as the phase transition to a tetragonal phase is approached. The latter is likely due to an increased domain wall mobility close to the first order transition temperature, which also gives rise to an increased frequency dispersion. Large reversible direct piezoelectric responses d33>1600pm/V are observed for both compositions, which increase dramatically close to the transition temperature. Most importantly, the reversible contribution is always much larger than the irreversible part in the low temperature, domain-engineered phase, the latter accounting for around 20% of the response in PZN-8PT, at 40°C, and 5% in PZN-4.5PT. The importance of this result to the validity of the adaptive phase model is discussed.

  14. Low Temperature Synthesis, Chemical and Electrochemical Characterization of LiNi(x)Co(1-x)O2 (0 less than x less than 1)

    Science.gov (United States)

    Nanjundaswamy, K. S.; Standlee, D.; Kelly, C. O.; Whiteley, R. V., Jr.

    1997-01-01

    A new method of synthesis for the solid solution cathode materials LiNi(x)Co(1-x)O2 (0 less than x less than 1) involving enhanced reactions at temperatures less than or equal to 700 deg. C, between metal oxy-hydroxide precursors MOOH (M = Ni, Co) and Li-salts (Li2CO3, LiOH, and LiNO3) has been investigated. The effects of synthesis conditions and sources of Li, on phase purity, microstructure, and theoretical electrochemical capacity (total M(3+) content) are characterized by powder X-ray diffraction analysis, scanning electron microscopy, chemical analysis and room temperature magnetic susceptibility. An attempt has been made to correlate the electrochemical properties with the synthesis conditions and microstructure.

  15. Inversely-designed printed microwave ablation antenna for controlled temperature profile synthesis

    Science.gov (United States)

    Sharma, Shashwat; Sarris, Costas D.

    2017-02-01

    Microwave ablation (MWA) is based on localized heating of biological tissues, enabled by an electric field. Antennas for ablation are commonly designed in a forward approach to generate a temperature profile specific to the design. The concept of an inversely-designed MWA antenna, consisting of printed dipoles, is presented herein. This design can be configured to synthesize a desired target temperature profile by controlling and optimizing its current distribution, as demonstrated by simulations. This concept provides the functionality of a phased array on the tip of an interstitial device.

  16. An introduction of CO₂ conversion by dry reforming with methane and new route of low-temperature methanol synthesis.

    Science.gov (United States)

    Shi, Lei; Yang, Guohui; Tao, Kai; Yoneyama, Yoshiharu; Tan, Yisheng; Tsubaki, Noritatsu

    2013-08-20

    converted in situ via one of two main routes. The first is to use Fischer-Tropsch synthesis (FTS), a process that catalytically converts syngas to hydrocarbons of varying molecular weights. The second is methanol synthesis. The latter has better atomic economy, since the oxygen atom in CO is included in the product and CO₂ can be blended into syngas as a reactant. However, production of methanol is very inefficient in this reaction: only 10-15% one-pass conversion typically at 5.0-10.0 MPa and 523-573 K, due to the severe thermodynamic limitations of this exothermal reaction (CO + 2H₂ = CH₃OH). In this Account, we propose and develop a new route of low-temperature methanol synthesis from CO₂-containing syngas only by adding alcohols, including methanol itself. These alcohols act as homogeneous cocatalysts and the solvent, realizing 70-100% one-pass conversion at only 5.0 MPa and 443 K. The key step is the reaction of the adsorbed formate species with alcohols to yield ester species at low temperatures, followed by the hydrogenation of ester by hydrogen atoms on metallic Cu. This changes the normal reaction path of conventional, high-temperature methanol synthesis from formate via methoxy to methanol.

  17. Electrode Design for Low Temperature Direct-Hydrocarbon Solid Oxide Fuel Cells

    Science.gov (United States)

    Chen, Fanglin (Inventor); Zhao, Fei (Inventor); Liu, Qiang (Inventor)

    2015-01-01

    In certain embodiments of the present disclosure, a solid oxide fuel cell is described. The solid oxide fuel cell includes a hierarchically porous cathode support having an impregnated cobaltite cathode deposited thereon, an electrolyte, and an anode support. The anode support includes hydrocarbon oxidation catalyst deposited thereon, wherein the cathode support, electrolyte, and anode support are joined together and wherein the solid oxide fuel cell operates a temperature of 600.degree. C. or less.

  18. The theory, direction, and magnitude of ecosystem fire probability as constrained by precipitation and temperature

    Science.gov (United States)

    Guyette, Richard; Stambaugh, Michael C.; Dey, Daniel

    2017-01-01

    The effects of climate on wildland fire confronts society across a range of different ecosystems. Water and temperature affect the combustion dynamics, irrespective of whether those are associated with carbon fueled motors or ecosystems, but through different chemical, physical, and biological processes. We use an ecosystem combustion equation developed with the physical chemistry of atmospheric variables to estimate and simulate fire probability and mean fire interval (MFI). The calibration of ecosystem fire probability with basic combustion chemistry and physics offers a quantitative method to address wildland fire in addition to the well-studied forcing factors such as topography, ignition, and vegetation. We develop a graphic analysis tool for estimating climate forced fire probability with temperature and precipitation based on an empirical assessment of combustion theory and fire prediction in ecosystems. Climate-affected fire probability for any period, past or future, is estimated with given temperature and precipitation. A graphic analyses of wildland fire dynamics driven by climate supports a dialectic in hydrologic processes that affect ecosystem combustion: 1) the water needed by plants to produce carbon bonds (fuel) and 2) the inhibition of successful reactant collisions by water molecules (humidity and fuel moisture). These two postulates enable a classification scheme for ecosystems into three or more climate categories using their position relative to change points defined by precipitation in combustion dynamics equations. Three classifications of combustion dynamics in ecosystems fire probability include: 1) precipitation insensitive, 2) precipitation unstable, and 3) precipitation sensitive. All three classifications interact in different ways with variable levels of temperature. PMID:28704457

  19. Synthesis of Fluorescent Gelators and Direct Observation of Gelation with a Fluorescence Microscope.

    Science.gov (United States)

    Hanabusa, Kenji; Ueda, Takuya; Takata, Shingo; Suzuki, Masahiro

    2016-11-14

    Fluorescein-, benzothiazole-, quinoline-, stilbene-, and carbazole-containing fluorescent gelators have been synthesized by connecting gelation-driving segments, including l-isoleucine, l-valine, l-phenylalanine, l-leucine residue, cyclo(l-asparaginyl-l-phenylalanyl), and trans-(1R,2R)-diaminocyclohexane. The emission behaviors of the gelators were investigated, and their gelation abilities studied against 15 solvents. The minimum gel concentration, variable-temperature spectroscopy, transmission electron microscopy, scanning electron microscopy, fluorescence microscopy (FM), and confocal laser scanning microscopy (CLSM) were used to characterize gelation. The intermolecular hydrogen bonding between the N-H and C=O of amide, van der Waals interactions and π-π stacking play important roles in gelation. The colors of emission are related to the fluorescence structures of gelators. Fibrous aggregates characterized by the color of their emission were observed by FM. 3D images are produced by the superposition of images captured by CLSM every 0.1 μm to a settled depth. The 3D images show that the large micrometer-sized aggregates spread out three dimensionally. FM observations of mixed gelators are studied. In the case of gelation, two structurally related gelators with the same gelation-driving segment lead to the gelators build up of the same aggregates through similar hydrogen-bonding patterns. When two gelators with structurally different gelation-driving segments induce gelation, the gelators build up each aggregate through individual hydrogen-bonding patterns. A fluorescent reagent that was incorporated into the aggregates of gels through van der Waals interactions was developed. The addition of this fluorescent reagent enables the successful observation of nonfluorescent gelators' aggregates by FM. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Direct Synthesis of MnO2 Nanorods on Carbon Cloth as Flexible Supercapacitor Electrode

    Directory of Open Access Journals (Sweden)

    Shuang Xi

    2017-01-01

    Full Text Available MnO2 nanorod/carbon cloth (MnO2/CC composites were prepared through in situ redox deposition as freestanding electrodes for flexible supercapacitors. The CC substrates possessing porous and interconnecting structures enable the uniform decoration of MnO2 nanorods on each fiber, thus forming conformal coaxial micro/nanocomposites. Three-dimensional CC can provide considerable specific surface area for high mass loading of MnO2, and the direct deposition process without using polymeric binders enables reliable electrical connection of MnO2 with CC. The effect of MnO2 decoration on the electrochemical performances was further investigated, indicating that the electrode prepared with 40 min deposition time shows high specific capacitance (220 F/g at a scan rate of 5 mV/s and good cycling property (90% of the initial specific capacitance was maintained after 2500 cycles in 1 M Na2SO4 aqueous solution. This enhanced electrochemical performance is ascribed to the synergistic effect of good conductivity of carbon substrates as well as outstanding pseudocapacitance of MnO2 nanorods. The obtained MnO2/CC compositing electrode with the advantages of low cost and easy fabrication is promising in applications of flexible supercapacitors.

  1. Synthesis of Findings, Current Investigations, and Future Directions: Operation Brain Trauma Therapy.

    Science.gov (United States)

    Kochanek, Patrick M; Bramlett, Helen M; Shear, Deborah A; Dixon, C Edward; Mondello, Stefania; Dietrich, W Dalton; Hayes, Ronald L; Wang, Kevin K W; Poloyac, Samuel M; Empey, Philip E; Povlishock, John T; Mountney, Andrea; Browning, Megan; Deng-Bryant, Ying; Yan, Hong Q; Jackson, Travis C; Catania, Michael; Glushakova, Olena; Richieri, Steven P; Tortella, Frank C

    2016-03-15

    Operation Brain Trauma Therapy (OBTT) is a fully operational, rigorous, and productive multicenter, pre-clinical drug and circulating biomarker screening consortium for the field of traumatic brain injury (TBI). In this article, we synthesize the findings from the first five therapies tested by OBTT and discuss both the current work that is ongoing and potential future directions. Based on the results generated from the first five therapies tested within the exacting approach used by OBTT, four (nicotinamide, erythropoietin, cyclosporine A, and simvastatin) performed below or well below what was expected based on the published literature. OBTT has identified, however, the early post-TBI administration of levetiracetam as a promising agent and has advanced it to a gyrencephalic large animal model--fluid percussion injury in micropigs. The sixth and seventh therapies have just completed testing (glibenclamide and Kollidon VA 64), and an eighth drug (AER 271) is in testing. Incorporation of circulating brain injury biomarker assessments into these pre-clinical studies suggests considerable potential for diagnostic and theranostic utility of glial fibrillary acidic protein in pre-clinical studies. Given the failures in clinical translation of therapies in TBI, rigorous multicenter, pre-clinical approaches to therapeutic screening such as OBTT may be important for the ultimate translation of therapies to the human condition.

  2. Shape-directing role of cetyltrimethylammonium bromide on the morphology of extracellular synthesis of silver nanoparticles

    Directory of Open Access Journals (Sweden)

    Shaeel Ahmed Al-Thabaiti

    2015-07-01

    Full Text Available Oriental plane leaf extracts were used as a reducing-, stabilizing- and capping-agent for the preparation of silver nanoparticles (AgNPs for the first time. The size, shape, size distribution and optical properties strongly depend on the experimental conditions, absence, and presence of shape-directing cetyltrimethylammonium bromide (CTAB. UV–vis spectroscopy, transmission electron microscopy and selected electron diffraction ring patterns were used to determine the morphology of resulting AgNPs at different time intervals. The spectra showed a surface Plasmon resonance (SPR peak at 450 nm which is the characteristic of spherical AgNPs (diameter ranging from 10 to 30 nm. The peak shifted to shorter wavelength (blue shift from 450 to 425 nm and sharpness of the peak also decreases in the presence of CTAB which might be due to the capping action of CTAB. A layer of ca. 3 nm around a group of the AgNPs in which the inner layer is bound to the AgNPs surface via the active groups of the extract has been observed.

  3. Radiolytic Synthesis of Vinyl Polymer-Clay Nanocomposite Membranes for Direct Methanol Fuel Cell

    Directory of Open Access Journals (Sweden)

    Yoon-Seob Kim

    2014-01-01

    Full Text Available The three-type vinyl polymer-clay nanocomposite membranes with sulfonate (–SO3Na are prepared by the solvent casting method after radiation-induced copolymerization for application of the direct methanol fuel cell (DMFC membrane. The three-type vinyl polymers in polymer-clay nanocomposite membranes are included in poly(styrene-co-sodium styrene sulfonate, poly(St-co-NaSS, poly(2-hydroxyethyl methacrylate-co-NaSS, poly(HEMA-co-NaSS, and poly(acrylic acid-co-NaSS, and poly(AAc-co-NaSS. The proton conductivity (S/cm, water uptake (%, and ion-exchange capacity (meq/g of the poly(St-co-NaSS-clay nanocomposite membrane are 0.0779, 32.4, 3.63, respectively. The MeOH permeability of the poly(St-co-NaSS-clay nanocomposite membrane is exhibited as 7.7×10−9 mmol·cm−2·s−1. DMFC performance for poly(St-co-NaSS-clay nanocomposite membrane is also measured in cell voltage and power density verses current density. As results, the poly(St-co-NaSS-clay nanocomposite membrane can be used as a DMFC membrane on behalf of the commercial Nafion membrane.

  4. Low-temperature synthesis of zeolite from perlite waste — Part I: review of methods and phase compositions of resulting products

    Science.gov (United States)

    Król, Magdalena; Morawska, Justyna; Mozgawa, Włodzimierz; Pichór, Waldemar

    2014-09-01

    In this paper a review of the recent studies on the synthesis of zeolites from expanded perlite under hydrothermal conditions is presented. Attention is paid to possible outcomes of synthesis from low cost glass material, such as perlite. The study also investigates the phase composition of zeolitic materials obtained by modification of by-product derived from an expanded perlite production process. The synthesis was made using the hydrothermal method with sodium hydroxide under autogenous pressure at a temperature below 100 °C for 1 to 72 h. It was possible to obtain a zeolitic material at a temperature as low as 60 °C using 4.0 M NaOH. The X-ray diffraction pattern showed the biggest peak intensity of zeolite X with 4.0 M NaOH at the temperature of 70 °C. During synthesis at higher temperature zeolite Na-P1 (with 3.0 M NaOH at 90 °C) and hydroxysodalite (with 5.0 M NaOH at 90 °C) were obtained.

  5. Temperature-controlled synthesis of substituted pyridine derivatives via the [5C + 1N] annulation of 1,1-bisalkylthio-1,4-pentanedienes and ammonium acetate.

    Science.gov (United States)

    Hu, Jianglei; Zhang, Qian; Yuan, Hongjuan; Liu, Qun

    2008-03-21

    A novel temperature-controlled one-pot synthesis of substituted pyridine derivatives via [5C + 1N] annulation of 1,1-bisalkylthio-1,4-pentanedienes and ammonium acetate is developed, and possible mechanisms leading to the divergent formation of the two types of pyridines are discussed.

  6. GREEN SYNTHESIS OF SILVER AND PALLADIUM NANOPARTICLES AT ROOM TEMPERATURE USING COFFEE AND TEA EXTRACT

    Science.gov (United States)

    An extremely simple green approach that generates bulk quantities of nanocrystals of noble metals such as silver (Ag) and palladium (Pd) using coffee and tea extract at room temperature is described. The single-pot method uses no surfactant, capping agent, and/or template. The ob...

  7. Global synthesis of the temperature sensitivity of leaf litter breakdown in streams and rivers

    Science.gov (United States)

    Jennifer J. Follstad Shah; John S. Kominoski; Marcelo Ardón; Walter K. Dodds; Mark O. Gessner; Natalie A. Griffiths; Charles P. Hawkins; Sherri L. Johnson; Antoine Lecerf; Carri J. LeRoy; David W. P. Manning; Amy D. Rosemond; Robert L. Sinsabaugh; Christopher M. Swan; Jackson R. Webster; Lydia H. Zeglin

    2017-01-01

    Streams and rivers are important conduits of terrestrially derived carbon (C) to atmospheric and marine reservoirs. Leaf litter breakdown rates are expected to increase as water temperatures rise in response to climate change. The magnitude of increase in breakdown rates is uncertain, given differences in litter quality and microbial and detritivore community...

  8. Temperature and soil organic matter decomposition rates - synthesis of current knowledge and a way forward

    Science.gov (United States)

    Richard T. Conant; Michael Ryan; Goran I. Agren; Hannah E. Birge; Eric A. Davidson; Peter E. Eliasson; Sarah E. Evans; Serita D. Frey; Christian P. Giardina; Francesca M. Hopkins; Riitta Hyvonen; Miko U. F . Kirschbaum; Jocelyn M. Lavallee; Jens Leifeld; William J. Parton; Jessica Megan Steinweg; Matthew D. Wallenstein; J . A. Martin Wetterstedt; Mark A. Bradford

    2011-01-01

    The response of soil organic matter (OM) decomposition to increasing temperature is a critical aspect of ecosystem responses to global change. The impacts of climate warming on decomposition dynamics have not been resolved due to apparently contradictory results from field and lab experiments, most of which has focused on labile carbon with short turnover times. But...

  9. Low temperature synthesis of nanosized Mn1–xZnxFe2O4 ferrites ...

    Indian Academy of Sciences (India)

    There is a systematic decrease in the particle size, Curie temperature and magnetization with the increase in the Zn2+ ion doping, measured using magneto thermal gravimetric analysis (MTGA) and vibrating sample magnetometer (VSM), respectively. The lattice constant is found to be constantly decreasing till = 0.6 and ...

  10. Self-exothermic reaction prompted synthesis of single-layered graphene quantum dots at room temperature.

    Science.gov (United States)

    Chen, Bin Bin; Li, Rong Sheng; Liu, Meng Li; Zhang, Hong Zhi; Huang, Cheng Zhi

    2017-05-02

    The easy fabrication of single-layered graphene quantum dots (s-GQDs) still faces challenge. Herein, we report an efficient route to fabricate s-GQDs within 5 min at room temperature by introducing a simple self-exothermic reaction. The as-prepared s-GQDs can specifically bind with aluminium ions to produce an aggregation-induced emission enhancement effect.

  11. Aqueous synthesis of porous platinum nanotubes at room temperature and their intrinsic peroxidase-like activity.

    Science.gov (United States)

    Cai, Kai; Lv, Zhicheng; Chen, Kun; Huang, Liang; Wang, Jing; Shao, Feng; Wang, Yanjun; Han, Heyou

    2013-07-11

    Platinum nanotubes (PtNTs) exhibiting high porosity were constructed by sacrificing the exterior of tellurium nanowires (TeNWs) and disintegrating the inner part spontaneously in aqueous solution at room temperature, in which the Kirkendall effect may play an important role. The present PtNTs exhibited intrinsic peroxidase-like activity in the presence of H2O2.

  12. Global synthesis of the temperature sensitivity of leaf litter breakdown in streams and rivers.

    Science.gov (United States)

    Follstad Shah, Jennifer J; Kominoski, John S; Ardón, Marcelo; Dodds, Walter K; Gessner, Mark O; Griffiths, Natalie A; Hawkins, Charles P; Johnson, Sherri L; Lecerf, Antoine; LeRoy, Carri J; Manning, David W P; Rosemond, Amy D; Sinsabaugh, Robert L; Swan, Christopher M; Webster, Jackson R; Zeglin, Lydia H

    2017-08-01

    Streams and rivers are important conduits of terrestrially derived carbon (C) to atmospheric and marine reservoirs. Leaf litter breakdown rates are expected to increase as water temperatures rise in response to climate change. The magnitude of increase in breakdown rates is uncertain, given differences in litter quality and microbial and detritivore community responses to temperature, factors that can influence the apparent temperature sensitivity of breakdown and the relative proportion of C lost to the atmosphere vs. stored or transported downstream. Here, we synthesized 1025 records of litter breakdown in streams and rivers to quantify its temperature sensitivity, as measured by the activation energy (Ea , in eV). Temperature sensitivity of litter breakdown varied among twelve plant genera for which Ea could be calculated. Higher values of Ea were correlated with lower-quality litter, but these correlations were influenced by a single, N-fixing genus (Alnus). Ea values converged when genera were classified into three breakdown rate categories, potentially due to continual water availability in streams and rivers modulating the influence of leaf chemistry on breakdown. Across all data representing 85 plant genera, the Ea was 0.34 ± 0.04 eV, or approximately half the value (0.65 eV) predicted by metabolic theory. Our results indicate that average breakdown rates may increase by 5-21% with a 1-4 °C rise in water temperature, rather than a 10-45% increase expected, according to metabolic theory. Differential warming of tropical and temperate biomes could result in a similar proportional increase in breakdown rates, despite variation in Ea values for these regions (0.75 ± 0.13 eV and 0.27 ± 0.05 eV, respectively). The relative proportions of gaseous C loss and organic matter transport downstream should not change with rising temperature given that Ea values for breakdown mediated by microbes alone and microbes plus detritivores were similar at the global

  13. "In-gel" purified ditags direct synthesis of highly efficient SAGE Libraries

    Directory of Open Access Journals (Sweden)

    Sloan Andrew E

    2002-08-01

    Full Text Available Abstract Background SAGE (serial analysis of gene expression is a recently developed technique for systematic analysis of eukaryotic transcriptomes. The most critical step in the SAGE method is large scale amplification of ditags which are then are concatemerized for the construction of representative SAGE libraries. Here, we report a protocol for purifying these ditags via an 'in situ' PAGE purification method. This generates ditags free of linker contaminations, making library construction simpler and more efficient. Results Ditags used to generate SAGE libraries were demarcated 'in situ' on preparative polyacrylamide gels using XC and BPB dyes, which precisely straddle the ditag band when a 16% PAGE gel (19:1 acrylamide:bis, 5% cross linker is used to resolve the DNA bands. Here, the ditag DNA was directly excised from gel without visualization via EtBr or fluorescent dye staining, resulting in highly purified ditag DNA free of contaminating linkers. These ditags could be rapidly self ligated even at 4°C to generate concatemers in a controlled manner, which in turn enabled us to generate highly efficient SAGE libraries. This reduced the labor and time necessary, as well as the cost. Conclusions This approach greatly simplified the ditag purification procedure for constructing SAGE libraries. Since the traditional post-run staining with EtBr or fluorescent dyes routinely results in cross contamination of a DNA band of interest by other DNA in the gel, the dry gel DNA excision method described here may also be amenable to other molecular biology techniques in which DNA purity is critically important.

  14. Enteric methane mitigation technologies for ruminant livestock: a synthesis of current research and future directions.

    Science.gov (United States)

    Patra, Amlan Kumar

    2012-04-01

    Enteric methane (CH(4)) emission in ruminants, which is produced via fermentation of feeds in the rumen and lower digestive tract by methanogenic archaea, represents a loss of 2% to 12% of gross energy of feeds and contributes to global greenhouse effects. Globally, about 80 million tonnes of CH(4) is produced annually from enteric fermentation mainly from ruminants. Therefore, CH(4) mitigation strategies in ruminants have focused to obtain economic as well as environmental benefits. Some mitigation options such as chemical inhibitors, defaunation, and ionophores inhibit methanogenesis directly or indirectly in the rumen, but they have not confirmed consistent effects for practical use. A variety of nutritional amendments such as increasing the amount of grains, inclusion of some leguminous forages containing condensed tannins and ionophore compounds in diets, supplementation of low-quality roughages with protein and readily fermentable carbohydrates, and addition of fats show promise for CH(4) mitigation. These nutritional amendments also increase the efficiency of feed utilization and, therefore, are most likely to be adopted by farmers. Several new potential technologies such as use of plant secondary metabolites, probiotics and propionate enhancers, stimulation of acetogens, immunization, CH(4) oxidation by methylotrophs, and genetic selection of low CH(4)-producing animals have emerged to decrease CH(4) production, but these require extensive research before they can be recommended to livestock producers. The use of bacteriocins, bacteriophages, and development of recombinant vaccines targeting archaeal-specific genes and cell surface proteins may be areas worthy of investigation for CH(4) mitigation as well. A combination of different CH(4) mitigation strategies should be adopted in farm levels to substantially decrease methane emission from ruminants. Evidently, comprehensive research is needed to explore proven and reliable CH(4) mitigation technologies

  15. Synthesis of periodic mesoporous organosilicas functionalized with different amine-organoalkoxysilanes via direct co-condensation

    Energy Technology Data Exchange (ETDEWEB)

    Suriyanon, Nakorn [International Postgraduate Programs in Environmental Management, Graduate School, Chulalongkorn University, Pathumwan, Bangkok 10330 (Thailand); Center of Excellence for Environmental and Hazardous Waste Management (EHWM), Pathumwan, Bangkok 10330 (Thailand); Punyapalakul, Patiparn [Center of Excellence for Environmental and Hazardous Waste Management (EHWM), Pathumwan, Bangkok 10330 (Thailand); Department of Environmental Engineering, Faculty of Engineering, Chulalongkorn University, Pathumwan, Bangkok 10330 (Thailand); Ngamcharussrivichai, Chawalit, E-mail: Chawalit.Ng@Chula.ac.th [Fuels Research Center, Department of Chemical Technology, Faculty of Science, Chulalongkorn University, Pathumwan, Bangkok 10330 (Thailand); Center of Excellence on Petrochemical and Materials Technology (PETROMAT), Chulalongkorn University, Pathumwan, Bangkok 10330 (Thailand)

    2015-01-15

    A series of amine-functionalized periodic mesoporous organosilicas (PMOs) were synthesized from bis(triethoxysilyl)ethane via surfactant-templating using supramolecular assemblies of hexadecyltrimethylammonium chloride under basic conditions. Functionalization of the PMO materials was performed via direct co-condensation in the presence of mono-, di- or tri-amine-organoalkoxysilanes. The effect of the type and concentration of the added organosilanes on the physicochemical properties of the functionalized PMOs were investigated. Thermogravimetric/differential thermal analysis (TG/DTA) and Fourier transform infrared spectroscopy (FTIR) confirmed the presence of the inorganic–organic hybrid framework functionalized with the amine groups. The total nitrogen content of the functionalized PMOs ranged from 0.26 to 1.27 mmol/g. The materials possessed a hexagonal lattice with the highly ordered mesostructure being preserved after the amine-functionalization as evidenced by X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM). The N{sub 2} adsorption–desorption measurement revealed that the materials had high specific surface areas (963–1252 m{sup 2}/g) and a relatively high total pore volume (0.52–0.85 cm{sup 3}/g). The mesopore size and wall thickness of these materials varied in relation with the molecular size and the loading of the organosilanes. Moreover, the morphology of the PMO materials was increasingly transformed from irregular shaped particles to spheres with increasing amounts of amine-functional groups or with organo-functional groups with several amine units. - Highlights: • Periodic mesoporous organosilicas (PMOs) were functionalized via co-condensation. • Long-chain organosilane with three amine units was employed a precursor. • Hexagonal mesostructure of PMO was preserved at a 40 mol% loading level. • Amine-functionalized PMOs had a high surface area and total pore volume. • Their morphology depended on the

  16. Highly stable layered double hydroxide colloids: a direct aqueous synthesis route from hybrid polyion complex micelles.

    Science.gov (United States)

    Layrac, Géraldine; Destarac, Mathias; Gérardin, Corine; Tichit, Didier

    2014-08-19

    Aqueous suspensions of highly stable Mg/Al layered double hydroxide (LDH) nanoparticles were obtained via a direct and fully colloidal route using asymmetric poly(acrylic acid)-b-poly(acrylamide) (PAA-b-PAM) double hydrophilic block copolymers (DHBCs) as growth and stabilizing agents. We showed that hybrid polyion complex (HPIC) micelles constituted of almost only Al(3+) were first formed when mixing solutions of Mg(2+) and Al(3+) cations and PAA3000-b-PAM10000 due to the preferential complexation of the trivalent cations. Then mineralization performed by progressive hydroxylation with NaOH transformed the simple DHBC/Al(3+) HPIC micelles into DHBC/aluminum hydroxide colloids, in which Mg(2+) ions were progressively introduced upon further hydroxylation leading to the Mg-Al LDH phase. The whole process of LDH formation occurred then within the confined environment of the aqueous complex colloids. The hydrodynamic diameter of the DHBC/LDH colloids could be controlled: it decreased from 530 nm down to 60 nm when the metal complexing ratio R (R = AA/(Mg + Al)) increased from 0.27 to 1. This was accompanied by a decrease of the average size of individual LDH particles as R increased (for example from 35 nm at R = 0.27 down to 17 nm at R = 0.33), together with a progressive favored intercalation of polyacrylate rather than chloride ions in the interlayer space of the LDH phase. The DHBC/LDH colloids have interesting properties for biomedical applications, that is, high colloidal stability as a function of time, stability in phosphate buffered saline solution, as well as the required size distribution for sterilization by filtration. Therefore, they could be used as colloidal drug delivery systems, especially for hydrosoluble negatively charged drugs.

  17. Direct separation of arsenic and antimony oxides by high-temperature filtration with porous FeAl intermetallic.

    Science.gov (United States)

    Zhang, Huibin; Liu, Xinli; Jiang, Yao; Gao, Lin; Yu, Linping; Lin, Nan; He, Yuehui; Liu, C T

    2017-09-15

    A temperature-controlled selective filtration technology for synchronous removal of arsenic and recovery of antimony from the fume produced from reduction smelting process of lead anode slimes was proposed. The chromium (Cr) alloyed FeAl intermetallic with an asymmetric pore structure was developed as the high-temperature filter material after evaluating its corrosive resistance, structural stability and mechanical properties. The results showed that porous FeAl alloyed with 20wt.% Cr had a long term stability in a high-temperature sulfide-bearing environment. The separation of arsenic and antimony trioxides was realized principally based on their disparate saturated vapor pressures at specific temperature ranges and the asymmetric membrane of FeAl filter elements with a mean pore size of 1.8μm. Pilot-scale filtration tests showed that the direct separation of arsenic and antimony can be achieved by a one-step or two-step filtration process. A higher removal percentage of arsenic can reach 92.24% at the expense of 6∼7% loss of antimony in the two-step filtration process at 500∼550°C and 300∼400°C. The FeAl filters had still good permeable and mechanical properties with 1041h of uninterrupted service, which indicates the feasibility of this high-temperature filtration technology. Copyright © 2017. Published by Elsevier B.V.

  18. Energy Storage and Generation for Extreme Temperature and Pressure and Directional Measurement While Drilling Applications

    Energy Technology Data Exchange (ETDEWEB)

    Signorelli, Riccardo [FastCAP Systems Corporation, Boston, MA (United States); Cooley, John [FastCAP Systems Corporation, Boston, MA (United States)

    2015-10-14

    FastCAP Systems Corporation has successfully completed all milestones defined by the award DE-EE0005503. Under this program, FastCAP developed three critical subassemblies to TRL3 demonstrating proof of concept of a geothermal MWD power source. This power source includes an energy harvester, electronics and a novel high temperature ultracapacitor (“ultracap”) rechargeable energy storage device suitable for geothermal exploration applications. FastCAP’s ruggedized ultracapacitor (ultracap) technology has been proven and commercialized in oil and gas exploration operating to rated temperatures of 150°C. Characteristics of this technology are that it is rechargeable and relatively high power. This technology was the basis for the advancements in rechargeable energy storage under this project. The ultracap performs reliably at 250°C and beyond and operates over a wide operating temperature range: -5°C to 250°C. The ultracap has significantly higher power density than lithium thionyl chloride batteries, a non-rechargeable incumbent used in oil and gas drilling today. Several hermetically sealed, prototype devices were tested in our laboratories at constant temperatures of 250°C showing no significant degradation over 2000 hours of operation. Other prototypes were tested at Sandia National Lab in the month of April, 2015 for a third party performance validation. These devices showed outstanding performance over 1000 hours of operation at three rated temperatures, 200°C, 225°C and 250°C, with negligible capacitance degradation and minimal equivalent series resistance (ESR) increase. Similarly, FastCAP’s ruggedized electronics have been proven and commercialized in oil and gas exploration operating to rated temperatures of 150°C. This technology was the basis for the advancements in downhole electronics under this project. Principal contributions here focused on design for manufacture innovations that have reduced the prototype build cycle time by a factor

  19. Synthesis and characterization of CuGeO3 photocatalyst using Green Chemistry and its application for the degradation of direct black dye

    Directory of Open Access Journals (Sweden)

    Ashok. V. Borhade

    2013-03-01

    Full Text Available In this paper, we report synthesis of CuGeO3 photocatalyst by mechanochemical, solid state synthesis, method with green chemistry approach. The product obtained was characterized by various investigative techniques like UV-Diffuse Reflectance Spectroscopy, Fourier Transform Infrared Spectroscopy, X-ray Diffraction, Scanning Electron Microscopy, with Energy Dispersive X-ray Spectroscopy, and BET Surface area. The study confirm orthorhombic pervoskite crystal structure of photocatalyst with band gap 3.7 eV. The photocatalytic activity of the catalysts CuGeO3 was evaluated by photochemical bleaching of Direct black dye, under sun light.

  20. Synthesis, Characterization, and Low Temperature Sintering of Nanostructured BaWO4 for Optical and LTCC Applications

    Directory of Open Access Journals (Sweden)

    S. Vidya

    2013-01-01

    Full Text Available Synthesis of nano-BaWO4 by a modified combustion technique and its suitability for various applications are reported. The structure and phase purity of the sample analyzed by X-ray diffraction, Fourier transform Raman, and infrared spectroscopy show that the sample is phase pure with tetragonal structure. The particle size from the transmission electron microscopy is 22 nm. The basic optical properties and optical constants of the nano BaWO4 are studied using UV-visible absorption spectroscopy which showed that the material is a wide band gap semiconductor with band gap of 4.1 eV. The sample shows poor transmittance in ultraviolet region while maximum in visible-near infrared regions. The photoluminescence spectra show intense emission in blue region. The sample is sintered at low temperature of 810°C, without any sintering aid. Surface morphology of the sample is analyzed by scanning electron microscopy. The dielectric constant and loss factor measured at 5 MHz are 9 and 1.56×10-3. The temperature coefficient of dielectric constant is −22 ppm/°C. The experimental results obtained in the present work claim the potential use of nano BaWO4 as UV filters, transparent films for window layers on solar cells, antireflection coatings, scintillators, detectors, and for LTCC applications.