WorldWideScience

Sample records for borohydrides

  1. Manganese borohydride; synthesis and characterization

    OpenAIRE

    Richter, Bo; Ravnsbæk, Dorthe B.; Tumanov, Nikolay; Filinchuk, Yaroslav; Jensen, Torben R.

    2015-01-01

    Solvent-based synthesis and characterization of α-Mn(BH4)2 and a new nanoporous polymorph of manganese borohydride, γ-Mn(BH4)2, via a new solvate precursor, Mn(BH4)2·1/2S(CH3)2, is presented. Manganese chloride is reacted with lithium borohydride in a toluene/dimethylsulfide mixture at room temperature, which yields halide and solvent-free manganese borohydride after extraction with dimethylsulfide (DMS) and subsequent removal of residual solvent. This work constitutes the first example of es...

  2. A stable monomeric nickel borohydride.

    Science.gov (United States)

    Desrochers, Patrick J; LeLievre, Stacey; Johnson, Rosemary J; Lamb, Brian T; Phelps, Andrea L; Cordes, A W; Gu, Weiwei; Cramer, Stephen P

    2003-12-01

    A stable discrete nickel borohydride complex (Tp*NiBH(4) or Tp*NiBD(4)) was prepared using the nitrogen-donor ligand hydrotris(3,5-dimethylpyrazolyl)borate (Tp*-). This complex represents one of the best characterized nickel(II) borohydrides to date. Tp*NiBH(4) and Tp*NiBD(4) are stable toward air, boiling water, and high temperatures (mp > 230 degrees C dec). X-ray crystallographic measurements for Tp*NiBH(4) showed a six-coordinate geometry for the complex, with the nickel(II) center facially coordinated by three bridging hydrogen atoms from borohydride and a tridentate Tp(-) ligand. For Tp*NiBH(4), the empirical formula is C(15)H(26)B(2)N(6)Ni, a = 13.469(9) A, b = 7.740(1) A, c = 18.851(2) A, beta = 107.605(9) degrees, the space group is monoclinic P2(1)/c, and Z = 4. Infrared measurements confirmed the presence of bridging hydrogen atoms; both nu(B[bond]H)(terminal) and nu(B[bond]H)(bridging) are assignable and shifted relative to nu(B-D) of Tp*NiBD(4) by amounts in agreement with theory. Despite their hydrolytic stability, Tp*NiBH(4) and Tp*NiBD(4) readily reduce halocarbon substrates, leading to the complete series of Tp*NiX complexes (X = Cl, Br, I). These reactions showed a pronounced hydrogen/deuterium rate dependence (k(H)/k(D) approximately 3) and sharp isosbestic points in progressive electronic spectra. Nickel K-edge X-ray absorption spectroscopy (XAS) measurements of a hydride-rich nickel center were obtained for Tp*NiBH(4), Tp*NiBD(4), and Tp*NiCl. X-ray absorption near-edge spectroscopy results confirmed the similar six-coordinate geometries for Tp*NiBH(4) and Tp*NiBD(4). These contrasted with XAS results for the crystallographically characterized pseudotetrahedral Tp*NiCl complex. The stability of Tp*Ni-coordinated borohydride is significant given this ion's accelerated decomposition and hydrolysis in the presence of transition metals and simple metal salts. PMID:14632512

  3. Catalytic Hydrolysis of Borohydride for Fuel Cells

    Institute of Scientific and Technical Information of China (English)

    WANG Lianbang; ZHAN Xingyue; YANG Zhenzhen; MA Chun'an

    2011-01-01

    Borohydrides present interesting options for the electrochemical power generation acting either as hydrogen source or anodic fuel for direct borohydride fuel cells(DBFC).In this work,Mg-Ni composite synthesized by mechanically alloying method,used as the catalyst for the hydrolysis of borohydride,has been investigated.Co-doping treatment has been carried out for the purpose of improving the hydrolysis rate further.The as-prepared and Co-doped Mg-Ni composites with low cost showed high catalytic activity to the hydrolysis of borohydride for hydrogen generation.After Co-doping,the hydrogen generation rate was around 280 ml·g-1·min-1.Borohydride would be a promising hydrogen source for fuel cells.

  4. Modified borohydrides for reversible hydrogen storage

    Energy Technology Data Exchange (ETDEWEB)

    Au, Ming

    2005-08-29

    In attempt to develop lithium borohydrides as the reversible hydrogen storage materials with the high capacity, the feasibility to reduce dehydrogenation temperature of the lithium borohydride and moderate rehydrogenation condition has been explored. The commercial available lithium borohydride has been modified by ball milling with metal oxides and metal chlorides as the additives. The modified lithium borohydrides release 9 wt% hydrogen starting from 473K. The dehydrided modified lithium borohydrides absorb 7-9 wt% hydrogen at 873K and 7 MPa. The additive modification reduces dehydriding temperature from 673K to 473K and moderates rehydrogenation conditions to 923K and 15 MPa. XRD and SEM analysis discovered the formation of the intermediate compound TiB{sub 2} that may plays the key role in change the reaction path resulting the lower dehydriding temperature and reversibility. The reversible hydrogen storage capacity of the oxide modified lithium borohydrides decreases gradually during hydriding-dehydriding cycling due to the lost of the boron during dehydrogenation. But, it can be prevented by selecting the suitable additive, forming intermediate boron compounds and changing the reaction path. The additives reduce dehydriding temperature and improve the reversibility, it also reduces the hydrogen storage capacity. The best compromise can be reached by optimization of the additive loading and introducing new process other than ball milling.

  5. Ballmilling of metal borohydrides for hydrogen storage

    DEFF Research Database (Denmark)

    Sommer, Sanna

    2014-01-01

    . Specifically, the research undertaken targets CaB6 whose boron is in a octahedral network, or AlB2 whose boron is layered. These compounds were then reactive ball milled with alkali and alkaline earth metal under hydrogen pressure, with the intention of forming metal borohydrides. For CaB6, no clear sign...... is to hydrogenate simple compounds such as metalborides and hydrides with the intention of forming a new and more hydrogen rich borohydride. In contrast to mainstream research, the method of synthesis has been based on reactants that are expected to be found in the metal borohydride’s dehydrogenated state...

  6. Chitosan-supported Borohydride Reducing Agent

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A new chitosan-supported borohydride reducing reagent (CBER) was prepared by treatment of KBH4 with the resin of chitosan derivative, which was first synthesized fiom the reaction of cross-linked chitosan microsphere with glycidyl trimethylammonium chloride. CBER could reduce aromatic carbonyl compound to corresponding alcohol.

  7. Experimental investigation on lithium borohydride hydrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Goudon, J.P. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Universite de Bourgogne, 9 avenue Alain Savary, BP 47870, 21078 Dijon Cedex (France); SNPE Materiaux Energetiques, Centre de Recherches du Bouchet, Laboratoire BCFB, 9 rue Lavoisier, 91710 Vert-le-Petit (France); Bernard, F. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Universite de Bourgogne, 9 avenue Alain Savary, BP 47870, 21078 Dijon Cedex (France); Renouard, J.; Yvart, P. [SNPE Materiaux Energetiques, Centre de Recherches du Bouchet, Laboratoire BCFB, 9 rue Lavoisier, 91710 Vert-le-Petit (France)

    2010-10-15

    Lithium borohydride, one of the highest energy density chemical energy carriers, is considered as an attractive potential hydrogen storage material due to its high gravimetric hydrogen density (19.6%). Belonging to borohydride compounds, it presents a real issue to overcome aims fixed by the U.S. Department of Energy in the field of energy, and so crystallizes currently attention and effort to use this material for large scale civil and military applications. However, due to its important hygroscopicity, lithium borohydride is a hazardous material which requires specific handling conditions for industrial aspects. In order to understand much more the reaction mechanism involved between LiBH{sub 4} and the water vapor which leads to the native material dehydrogenation, several experimental techniques such as X-ray Photoelectrons Spectroscopy (XPS), Raman spectroscopy, X-Ray Diffraction (XRD) or thermal analysis (TGA/DTA) were investigated. Indeed, depending on water stoichiometric coefficient, several reactions are suggested in literature but the lithium borohydride hydrolysis way reaction scheme is still uncertain. Investigations exhibited interesting results and, highlighted the formation of lithium metaborate dihydrate LiBO{sub 2},2H{sub 2}O as hydrolysis product via such a solid-gas reaction. (author)

  8. BIMETALLIC LITHIUM BOROHYDRIDES TOWARD REVERSIBLE HYDROGEN STORAGE

    Energy Technology Data Exchange (ETDEWEB)

    Au, M.

    2010-10-21

    Borohydrides such as LiBH{sub 4} have been studied as candidates for hydrogen storage because of their high hydrogen contents (18.4 wt% for LiBH{sub 4}). Limited success has been made in reducing the dehydrogenation temperature by adding reactants such as metals, metal oxides and metal halides. However, full rehydrogenation has not been realized because of multi-step decomposition processes and the stable intermediate species produced. It is suggested that adding second cation in LiBH{sub 4} may reduce the binding energy of B-H. The second cation may also provide the pathway for full rehydrogenation. In this work, several bimetallic borohydrides were synthesized using wet chemistry, high pressure reactive ball milling and sintering processes. The investigation found that the thermodynamic stability was reduced, but the full rehydrogenation is still a challenge. Although our experiments show the partial reversibility of the bimetallic borohydrides, it was not sustainable during dehydriding-rehydriding cycles because of the accumulation of hydrogen inert species.

  9. Catalytic polymeric electrodes for direct borohydride fuel cells

    Science.gov (United States)

    Bayatsarmadi, Bita; Peters, Alice; Talemi, Pejman

    2016-08-01

    The direct borohydride fuel cell (DBFC) is a new class of fuel cells that produces non-toxic by-products and has a potential for a high voltage and high energy density. A major challenge in developing efficient DBFCs is the development of an efficient, stable, and economic catalyst for the oxidation of borohydride. In this paper, we report the use of conducting polymer Poly(3,4-ethylenedioxythiophene) (PEDOT) as electrocatalysts in DBFC. PEDOT electrodes prepared by vacuum phase polymerization exhibited electrocatalytic behavior towards oxidation of borohydride and reduction of hydrogen peroxide. Spectroscopic analysis of samples showed that PEDOT can act as an interface for electron transfer from borohydride ions. Comparing the polarization curves of DBFCs with PEDOT coated on graphite electrodes and cells with bare graphite electrodes, demonstrated higher voltage, maximum power density, and stability.

  10. Borohydride electro-oxidation on Pt single crystal electrodes

    OpenAIRE

    Briega-Martos, Valentín; Herrero, Enrique; Juan M Feliu

    2015-01-01

    The borohydride oxidation reaction on platinum single-crystal electrodes has been studied in sodium hydroxide solution using static and rotating conditions. The results show that borohydride electro-oxidation is a structure sensitive process on Pt surfaces. Significant changes in the measured currents are observed at low potentials. In this region, the Pt(111) electrode exhibits the lowest activity, whereas the highest currents are measured for the Pt(110) electrode. The behavior of the diffe...

  11. Oscillatory instabilities in the electrooxidation of borohydride on platinum

    Energy Technology Data Exchange (ETDEWEB)

    Machado, Eduardo G.; Varela, Hamilton, E-mail: varela@iqsc.usp.br [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Instituto de Quimica

    2014-03-15

    The borohydride ion has been pointed as a promising alternative fuel. Most of the investigation on its electrochemistry is devoted to the electrocatalytic aspects of its electrooxidation on platinum and gold surfaces. Besides the known kinetic limitations and intricate mechanism, our Group has recently found the occurrence of two regions of bi-stability and autocatalysis in the electrode potential during the open circuit interaction of borohydride and oxidized platinum surfaces. Following this previous contribution, the occurrence of more complicated phenomena is here presented: namely the presence of electrochemical oscillations during the electrooxidation of borohydride on platinum in alkaline media. Current oscillations were found to be associated to two distinct instability windows and characterized in the resistance-potential parameter plane. The dynamic features of such oscillations suggest the existence of distinct mechanisms according to the potential region. Previously published results obtained under non-oscillatory regime were used to give some hints on the surface chemistry behind the observed dynamics. (author)

  12. Methods to Stabilize and Destabilize Ammonium Borohydride

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, Thomas K.; Karkamkar, Abhijeet J.; Bowden, Mark E.; Besenbacher, Fleming; Jensen, Torben R.; Autrey, Thomas

    2013-01-21

    Ammonium borohydride, NH4BH4, has a high hydrogen content of ρm = 24.5 wt% H2 and releases 18 wt% H2 below T = 160 °C. However, the half-life of bulk NH4BH4 at ambient temperatures, ~6 h, is insufficient for practical applications. The decomposition of NH4BH4 (ABH2) was studied at variable hydrogen and argon back pressures to investigate possible pressure mediated stabilization effects. The hydrogen release rate from solid ABH2 at ambient temperatures is reduced by ~16 % upon increasing the hydrogen back pressure from 5 to 54 bar. Similar results were obtained using argon pressure and the observed stabilization may be explained by a positive volume of activation in the transition state leading to hydrogen release. Nanoconfinement in mesoporous silica, MCM-41, was investigated as alternative means to stabilize NH4BH4. However, other factors appear to significantly destabilize NH4BH4 and it rapidly decomposes at ambient temperatures into [(NH3)2BH2][BH4] (DADB) in accordance with the bulk reaction scheme. The hydrogen desorption kinetics from nanoconfined [(NH3)2BH2][BH4] is moderately enhanced as evidenced by a reduction in the DSC decomposition peak temperature of ΔT = -13 °C as compared to the bulk material. Finally, we note a surprising result, storage of DADB at temperature < -30 °C transformed, reversibly, the [(NH3)2BH2][BH4] into a new low temperature polymorph as revealed by both XRD and solid state MAS 11B MAS NMR. TA & AK are thankful for support from the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. A portion of the research was performed using EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle.

  13. A composite of borohydride and super absorbent polymer for hydrogen generation

    Science.gov (United States)

    Li, Z. P.; Liu, B. H.; Liu, F. F.; Xu, D.

    To develop a hydrogen source for underwater applications, a composite of sodium borohydride and super absorbent polymer (SAP) is prepared by ball milling sodium borohydride powder with SAP powder, and by dehydrating an alkaline borohydride gel. When sodium polyacrylate (NaPAA) is used as the SAP, the resulting composite exhibits a high rate of borohydride hydrolysis for hydrogen generation. A mechanism of hydrogen evolution from the NaBH 4-NaPAA composite is suggested based on structure analysis by X-ray diffraction and scanning electron microscopy. The effects of water and NiCl 2 content in the precursor solution on the hydrogen evolution behavior are investigated and discussed.

  14. Effect of sodium borohydride synthesis on NaBH4-H2 system economics

    International Nuclear Information System (INIS)

    The hazards and negative impacts of fossil fuel usage on environment and the prospect of fossil fuel depletion in near future have urged scientists to search for and use clean energy sources and alternative fuels. Hydrogen is the best fuel among others, which can minimize the effects of global warming. Although it is currently more expensive than other fuels, it will be cheaper following further developments in hydrogen technologies from production till end-use. Hydrogen storage is a critical issue in terms of safety and economics of hydrogen energy system. Chemical hydrides are an attractive hydrogen storage method due to their potential of achieving high volumetric and gravimetric storage densities. Among chemical hydrides, sodium borohydride (NaBH4) is given a big attention, due to its 10.8% theoretical hydrogen storage capacity. Hydrogen, which can be released by sodium borohydride hydrolysis reaction on-site, can be used in a proton exchange membrane fuel cell (PEMFC) at anode. on the other hand, sodium borohydride solution can be used directly in a borohydride fuel cell (DBFC) at anode. Like the other chemical hydrides, sodium borohydride has been an expensive material up to now, constituting a major obstacle to commercialization of sodium borohydride as a hydrogen storage method. This paper aims to give an approximate estimation process cost of the NaBH4-H2 system by taking into account both the energy and raw material costs, starting with sodium borohydride production till recycling of it. Two different methods to synthesize sodium borohydride are analyzed and their effects on total cost are compared. It was found that the usage of Bayer process to synthesize sodium borohydride makes the overall sodium borohydride - hydrogen system cost higher than the total cost of the alternative process which starts with the production of sodium borohydride from borax decahydrate. (authors)

  15. Borohydride electro-oxidation by Ag-doped lanthanum chromites

    Indian Academy of Sciences (India)

    S Suresh Balaji; A Usha; V V Giridhar

    2014-05-01

    The electrocatalytic activity of Ag-doped lanthanum chromites electrode materials viz., LaCr0.4Ag0.6O3 and LaCr0.7Ag0.3O3 prepared by decomposing the precursor complex is studied. Pure LaCrO3 is synthesized by combustion route using oxalic acid as a fuel. The decomposition behaviour of the assynthesized powder obtained in the latter method is characterized by TGA-DTA and XRD. Both the precursor complex and the as-synthesized powder are calcined at 900°C for 7 and 10 h, respectively. XRD of the final product after calcinations indicated the formation of perovskite phase with minor amounts of impurity phases of component oxides in the Ag-doped lanthanum chromites and pure perovskite phase in the undoped one. The surface morphology of the perovskites is studied by SEM. The electrocatalytic activity of the perovskite powders for borohydride oxidation is studied by using cyclic voltammetry (CV) at a catalyst loading of 0.7 mgcm−2 for both Ag-doped and undoped LaCrO3 coated on glassy carbon substrate. Calibration plots are obtained by plotting the anodic peak current versus concentration of borohydride in the range of 20-100 mM. The sensitivities of the three perovskites towards borohydride oxidation indicated that LaCr0.4Ag0.6O3 is the best among all the perovskites studied giving a value of 1.395 A/mM.

  16. Sodium borohydride reduction of aromatic carboxylic acids via methyl esters

    Indian Academy of Sciences (India)

    Aamer Saeed; Zaman Ashraf

    2006-09-01

    A number of important aromatic carboxylic acids precursors, or intermediates in the syntheses of natural products, are converted into methyl esters and reduced to the corresponding primary alcohols using a sodium borohydride-THF-methanol system. The alcohols are obtained in 70-92% yields in 2-5 hours, in a pure state. This two-step procedure not only provides a better alternative to aluminum hydride reduction of acids but also allows the selective reduction of esters in presence of acids, amides, nitriles or nitro functions which are not affected under these conditions.

  17. The direct borohydride fuel cell for UUV propulsion power

    Science.gov (United States)

    Lakeman, J. Barry; Rose, Abigail; Pointon, Kevin D.; Browning, Darren J.; Lovell, Keith V.; Waring, Susan C.; Horsfall, Jackie A.

    The development of proton exchange membrane and direct methanol fuel cell stacks is now well advanced for many applications. However, the significant performance advantages that these have over the battery for small to moderate scale applications will not be realised until a credible fuel source has been developed. The deficiencies of the PEMFC and DMFC can be eliminated by cation or anion-conducting membranes incorporated into a direct sodium borohydride fuel cell (DSBFC). The characterisation of membranes for the DSBFC is discussed. Novel membranes have been prepared which have resistance of an equal magnitude to the commercially available Nafion ® membrane.

  18. Metal Borohydrides synthesized from metal borides and metal hydrides

    DEFF Research Database (Denmark)

    Sommer, Sanna

    2014-01-01

    Aarhus C, Denmark email: gallafogh@hotmail.com / sanna-sommer@hotmail.com Magnesium boride, MgB2, ball milled with MH (M = Li, Na, Ca) followed by hydrogenation under high hydrogen pressure, readily forms the corresponding metal borohydrides, M(BH4)x (M = Li, Na, Ca) and MgH2 according to reaction scheme...... (1) [1]. MgB2 + MH → MBH4 + MgH2 (M = Li, Na, Ca) (1) Furthermore, formation of CaB6 during decomposition of Ca(BH4)2 is very important for the reaction to be reversible.[2] High gas pressure ball milling have been performed on the systems MgB2 – NaH and CaB6 – CaH2 – TiCl3 with formation of NaBH4...... and Ca(BH4)2, respectively [3,4]. An attempt to synthesize alkali and alkaline earth metal borohydrides from various borides by ball milling under high hydrogen pressure is presented here. MgB2, AlB2 and CaB6 have been milled with MHx (M = Li, Na, Mg, Ca) at p(H2) = 110 bar for 24 hours. All samples were...

  19. Synthesis of Borohydride and Catalytic Dehydrogenation by Hydrogel Based Catalyst

    Science.gov (United States)

    Boynuegri, Tugba Akkas; Karabulut, Ahmet F.; Guru, Metin

    2016-08-01

    This paper deals with the synthesis of calcium borohydride (Ca(BH4)2) as hydrogen storage material. Calcium chloride salt (CaCl2), magnesium hydride (MgH2), and boron oxide (B2O3) were used as reactants in the mechanochemical synthesis of Ca(BH4)2. The mechanochemical reaction was carried out by means of Spex type ball milling without applying high pressure and temperature. Parametric studies have been established at different reaction times and for different amounts of reactants at a constant ball to powder ratio (BPR) 4:1. The best combination was determined by Fourier Transform Infrared (FT-IR) analysis. According to the FT-IR analysis, reaction time, the first reaction parameter, was found as 1600 min. After the reaction time was fixed at 1600 min, the difference of the B-H peak areas was dependent on the amount of reactant MgH2 that was investigated. The amount of the reactant (MgH2), the second reaction parameter, was measured to be 2.85 times more than the stoichiometric amount of MgH2. According to our previous studies, BPR was selected as 4:1 for all experiments. Samples were prepared in a glove box under argon atmosphere but the time that elapsed for FT-IR analysis highly affected B-H bonds. B-H peak areas clearly decreased with time because of negative effect of ambient atmosphere. A catalyst was prepared by absorbing cobalt fluoride (CoF2) in poly (acrylamide-co-acrylic acid) hydrogel matrices type and its catalytic dehydrogenation performance that has been characterized by the catalytic reaction of sodium borohydride's known hydrogen capacity in an alkaline medium. The metal amount of hydrogel catalyst was determined as 135.82 mg Co by Atomic Absorption Spectroscopy (AAS). The specific dehydrogenation capacity of the Co active compound in the catalyst thanks to catalytic dehydrogenation of commercial sodium borohydride was measured as 1.66 mL H2/mg Co.

  20. Recent progress in metal borohydrides for hydrogen storage

    Energy Technology Data Exchange (ETDEWEB)

    Li, H.-W.; Yan, Y.; Orimo, S.-I. [Tohoku University, Institute for Materials Research (IMR), Sendai (Japan); Zuettel, A. [Department of the Environment, Energy and Mobility (EMPA), Abt. 138 ' Hydrogen and Energy' , Duebendorf (Switzerland); Jensen, C. M. [University of Hawaii, Department of Chemistry, Honolulu, HI (United States)

    2011-07-01

    The prerequisite for widespread use of hydrogen as an energy carrier is the development of new materials that can safely store it at high gravimetric and volumetric densities. Metal borohydrides M(BH{sub 4}){sub n} (n is the valence of metal M), in particular, have high hydrogen density, and are therefore regarded as one such potential hydrogen storage material. For fuel cell vehicles, the goal for on-board storage systems is to achieve reversible store at high density but moderate temperature and hydrogen pressure. To this end, a large amount of effort has been devoted to improvements in their thermodynamic and kinetic aspects. This review provides an overview of recent research activity on various M(BH{sub 4}){sub n}, with a focus on the fundamental dehydrogenation and rehydrogenation properties and on providing guidance for material design in terms of tailoring thermodynamics and promoting kinetics for hydrogen storage. (authors)

  1. Complex metal borohydrides: multifunctional materials for energy storage and conversion.

    Science.gov (United States)

    Mohtadi, Rana; Remhof, Arndt; Jena, Puru

    2016-09-01

    With the limited supply of fossil fuels and their adverse effect on the climate and the environment, it has become a global priority to seek alternate sources of energy that are clean, abundant, and sustainable. While sources such as solar, wind, and hydrogen can meet the world's energy demand, considerable challenges remain to find materials that can store and/or convert energy efficiently. This topical review focuses on one such class of materials, namely, multi-functional complex metal borohydrides that not only have the ability to store sufficient amount of hydrogen to meet the needs of the transportation industry, but also can be used for a new generation of metal ion batteries and solar cells. We discuss the material challenges in all these areas and review the progress that has been made to address them, the issues that still need to be resolved and the outlook for the future. PMID:27384871

  2. Complex metal borohydrides: multifunctional materials for energy storage and conversion

    Science.gov (United States)

    Mohtadi, Rana; Remhof, Arndt; Jena, Puru

    2016-09-01

    With the limited supply of fossil fuels and their adverse effect on the climate and the environment, it has become a global priority to seek alternate sources of energy that are clean, abundant, and sustainable. While sources such as solar, wind, and hydrogen can meet the world’s energy demand, considerable challenges remain to find materials that can store and/or convert energy efficiently. This topical review focuses on one such class of materials, namely, multi-functional complex metal borohydrides that not only have the ability to store sufficient amount of hydrogen to meet the needs of the transportation industry, but also can be used for a new generation of metal ion batteries and solar cells. We discuss the material challenges in all these areas and review the progress that has been made to address them, the issues that still need to be resolved and the outlook for the future.

  3. Reduction of Aldehydes and Ketones with Potassium Borohydride as Reductant

    Institute of Scientific and Technical Information of China (English)

    罗慧谋; 李毅群

    2005-01-01

    A series of aldehydes and ketones were reduced by potassium borohydride in an ionic liquid/water ([bmim]PF6/H2O) biphasic system to afford corresponding alcohol with high purity in excellent yields. The ionic liquid/water biphasic system could promote the chemoselectivity and the substituents such as nitro group and chlorine remained intact. Aromatic ketones were not as active as aromatic aldhydes and cyclic ketones owing to their higher steric hindrance. The ionic liquid could be recycled and reused. This protocol has notable advantages of no need of phase transfer catalyst and organic solvents, mild conditions, simple operation, short reaction time, ease work-up, high yields and recycling of the ionic liquid.

  4. PALLADIUM COATED STEEL ELECTRODE - PREPARATION, CHARACTERIZATION AND THEIR USE OF BOROHYDRIDE DETERMINATION

    OpenAIRE

    Karaboduk, Kuddusi; Hasdemir, Erdoğan; Aksu, Mehmet Levent

    2015-01-01

    The purpose of this study is the fabrication of a cost effective palladium coated steel electrode (pd-S) for the direct analysis of the sodium borohydride (BH4-). The electrode was prepared by the cyclic voltammetry. The electrode was observed to have a high catalytic effect on the oxidation of BH4-. The Pd-S surface was characterized with profilometri, scanning electron microscope, ferrocene test and electrochemical impedance spectroscopic technique. The effects of  borohydride concentration...

  5. Three-dimensional nanostructured Ni-Cu foams for borohydride oxidation

    Science.gov (United States)

    Santos, D. M. F.; Eugénio, S.; Cardoso, D. S. P.; Šljukić, B.; Montemor, M. F.

    2015-12-01

    Three-dimensional (3D) nanostructured nickel-copper (Ni-Cu) foams have been prepared by electrodeposition using a dynamic hydrogen template. These 3D materials were tested as electrodes for the borohydride oxidation reaction (BOR) in alkaline media for possible application as anodes of direct borohydride fuel cells. Their activity in BOR was studied using cyclic voltammetry, chronoamperometry, and chronopotentiometry and main reaction parameters and electrodes' stability were evaluated.

  6. The crystal chemistry of inorganic metal borohydrides and their relation to metal oxides.

    Science.gov (United States)

    Černý, Radovan; Schouwink, Pascal

    2015-12-01

    The crystal structures of inorganic homoleptic metal borohydrides are analysed with respect to their structural prototypes found amongst metal oxides in the inorganic databases such as Pearson's Crystal Data [Villars & Cenzual (2015). Pearson's Crystal Data. Crystal Structure Database for Inorganic Compounds, Release 2014/2015, ASM International, Materials Park, Ohio, USA]. The coordination polyhedra around the cations and the borohydride anion are determined, and constitute the basis of the structural systematics underlying metal borohydride chemistry in various frameworks and variants of ionic packing, including complex anions and the packing of neutral molecules in the crystal. Underlying nets are determined by topology analysis using the program TOPOS [Blatov (2006). IUCr CompComm. Newsl. 7, 4-38]. It is found that the Pauling rules for ionic crystals apply to all non-molecular borohydride crystal structures, and that the latter can often be derived by simple deformation of the close-packed anionic lattices c.c.p. and h.c.p., by partially removing anions and filling tetrahedral or octahedral sites. The deviation from an ideal close packing is facilitated in metal borohydrides with respect to the oxide due to geometrical and electronic considerations of the BH4(-) anion (tetrahedral shape, polarizability). This review on crystal chemistry of borohydrides and their similarity to oxides is a contribution which should serve materials engineers as a roadmap to design new materials, synthetic chemists in their search for promising compounds to be prepared, and materials scientists in understanding the properties of novel materials.

  7. Sodium borohydride removes aldehyde inhibitors for enhancing biohydrogen fermentation.

    Science.gov (United States)

    Lin, Richen; Cheng, Jun; Ding, Lingkan; Song, Wenlu; Zhou, Junhu; Cen, Kefa

    2015-12-01

    To enhance biohydrogen production from glucose and xylose in the presence of aldehyde inhibitors, reducing agent (i.e., sodium borohydride) was in situ added for effective detoxification. The detoxification efficiencies of furfural (96.7%) and 5-hydroxymethylfurfural (5-HMF, 91.7%) with 30mM NaBH4 were much higher than those of vanillin (77.3%) and syringaldehyde (69.3%). Biohydrogen fermentation was completely inhibited without detoxification, probably because of the consumption of nicotinamide adenine dinucleotide (NADH) by inhibitors reduction (R-CHO+2NADH→R-CH2OH+2NAD(+)). Addition of 30mM NaBH4 provided the reducing power necessary for inhibitors reduction (4R-CHO+NaBH4+2H2O→4R-CH2OH+NaBO2). The recovered reducing power in fermentation resulted in 99.3% recovery of the hydrogen yield and 64.6% recovery of peak production rate. Metabolite production and carbon conversion after detoxification significantly increased to 63.7mM and 81.9%, respectively. PMID:26342346

  8. Sodium borohydride removes aldehyde inhibitors for enhancing biohydrogen fermentation.

    Science.gov (United States)

    Lin, Richen; Cheng, Jun; Ding, Lingkan; Song, Wenlu; Zhou, Junhu; Cen, Kefa

    2015-12-01

    To enhance biohydrogen production from glucose and xylose in the presence of aldehyde inhibitors, reducing agent (i.e., sodium borohydride) was in situ added for effective detoxification. The detoxification efficiencies of furfural (96.7%) and 5-hydroxymethylfurfural (5-HMF, 91.7%) with 30mM NaBH4 were much higher than those of vanillin (77.3%) and syringaldehyde (69.3%). Biohydrogen fermentation was completely inhibited without detoxification, probably because of the consumption of nicotinamide adenine dinucleotide (NADH) by inhibitors reduction (R-CHO+2NADH→R-CH2OH+2NAD(+)). Addition of 30mM NaBH4 provided the reducing power necessary for inhibitors reduction (4R-CHO+NaBH4+2H2O→4R-CH2OH+NaBO2). The recovered reducing power in fermentation resulted in 99.3% recovery of the hydrogen yield and 64.6% recovery of peak production rate. Metabolite production and carbon conversion after detoxification significantly increased to 63.7mM and 81.9%, respectively.

  9. Understanding oscillatory phenomena in molecular hydrogen generation via sodium borohydride hydrolysis.

    Science.gov (United States)

    Budroni, M A; Biosa, E; Garroni, S; Mulas, G R C; Marchettini, N; Culeddu, N; Rustici, M

    2013-11-14

    The hydrolysis of borohydride salts represents one of the most promising processes for the generation of high purity molecular hydrogen under mild conditions. In this work we show that the sodium borohydride hydrolysis exhibits a fingerprinting periodic oscillatory transient in the hydrogen flow over a wide range of experimental conditions. We disproved the possibility that flow oscillations are driven by supersaturation phenomena of gaseous bubbles in the reactive mixture or by a nonlinear thermal feedback according to a thermokinetic model. Our experimental results indicate that the NaBH4 hydrolysis is a spontaneous inorganic oscillator, in which the hydrogen flow oscillations are coupled to an "oscillophor" in the reactive solution. The discovery of this original oscillator paves the way for a new class of chemical oscillators, with fundamental implications not only for testing the general theory on oscillations, but also with a view to chemical control of borohydride systems used as a source of hydrogen based green fuel. PMID:24084866

  10. Removal of molecular adsorbates on gold nanoparticles using sodium borohydride in water.

    Science.gov (United States)

    Ansar, Siyam M; Ameer, Fathima S; Hu, Wenfang; Zou, Shengli; Pittman, Charles U; Zhang, Dongmao

    2013-03-13

    The mechanism of sodium borohydride removal of organothiols from gold nanoparticles (AuNPs) was studied using an experimental investigation and computational modeling. Organothiols and other AuNP surface adsorbates such as thiophene, adenine, rhodamine, small anions (Br(-) and I(-)), and a polymer (PVP, poly(N-vinylpyrrolidone)) can all be rapidly and completely removed from the AuNP surfaces. A computational study showed that hydride derived from sodium borohydride has a higher binding affinity to AuNPs than organothiols. Thus, it can displace organothiols and all the other adsorbates tested from AuNPs. Sodium borohydride may be used as a hazard-free, general-purpose detergent that should find utility in a variety of AuNP applications including catalysis, biosensing, surface enhanced Raman spectroscopy, and AuNP recycle and reuse.

  11. Hydrogen rotational and translational diffusion in calcium borohydride from quasielastic neutron scattering and DFT

    DEFF Research Database (Denmark)

    Blanchard, Didier; Riktor, M.D.; Maronsson, Jon Bergmann;

    2010-01-01

    Hydrogen dynamics in crystalline calcium borohydride can be initiated by long-range diffusion or localized motion such as rotations, librations, and vibrations. Herein, the rotational and translational diffusion were studied by quasielastic neutron scattering (QENS) by using two instruments with ...

  12. Self-Printing on Graphitic Nanosheets with Metal Borohydride Nanodots for Hydrogen Storage

    Science.gov (United States)

    Li, Yongtao; Ding, Xiaoli; Zhang, Qingan

    2016-01-01

    Although the synthesis of borohydride nanostructures is sufficiently established for advancement of hydrogen storage, obtaining ultrasmall (sub-10 nm) metal borohydride nanocrystals with excellent dispersibility is extremely challenging because of their high surface energy, exceedingly strong reducibility/hydrophilicity and complicated composition. Here, we demonstrate a mechanical-force-driven self-printing process that enables monodispersed (~6 nm) NaBH4 nanodots to uniformly anchor onto freshly-exfoliated graphitic nanosheets (GNs). Both mechanical-forces and borohydride interaction with GNs stimulate NaBH4 clusters intercalation/absorption into the graphite interlayers acting as a ‘pen’ for writing, which is accomplished by exfoliating GNs with the ‘printed’ borohydrides. These nano-NaBH4@GNs exhibit favorable thermodynamics (decrease in ∆H of ~45%), rapid kinetics (a greater than six-fold increase) and stable de-/re-hydrogenation that retains a high capacity (up to ~5 wt% for NaBH4) compared with those of micro-NaBH4. Our results are helpful in the scalable fabrication of zero-dimensional complex hydrides on two-dimensional supports with enhanced hydrogen storage for potential applications. PMID:27484735

  13. Exploiting hydrophobic borohydride-rich ionic liquids as faster-igniting rocket fuels.

    Science.gov (United States)

    Liu, Tianlin; Qi, Xiujuan; Huang, Shi; Jiang, Linhai; Li, Jianling; Tang, Chenglong; Zhang, Qinghua

    2016-02-01

    A family of hydrophobic borohydride-rich ionic liquids was developed, which exhibited the shortest ignition delay times of 1.7 milliseconds and the lowest viscosity (10 mPa s) of hypergolic ionic fluids, demonstrating their great potential as faster-igniting rocket fuels to replace toxic hydrazine derivatives in liquid bipropellant formulations.

  14. Self-Printing on Graphitic Nanosheets with Metal Borohydride Nanodots for Hydrogen Storage.

    Science.gov (United States)

    Li, Yongtao; Ding, Xiaoli; Zhang, Qingan

    2016-01-01

    Although the synthesis of borohydride nanostructures is sufficiently established for advancement of hydrogen storage, obtaining ultrasmall (sub-10 nm) metal borohydride nanocrystals with excellent dispersibility is extremely challenging because of their high surface energy, exceedingly strong reducibility/hydrophilicity and complicated composition. Here, we demonstrate a mechanical-force-driven self-printing process that enables monodispersed (~6 nm) NaBH4 nanodots to uniformly anchor onto freshly-exfoliated graphitic nanosheets (GNs). Both mechanical-forces and borohydride interaction with GNs stimulate NaBH4 clusters intercalation/absorption into the graphite interlayers acting as a 'pen' for writing, which is accomplished by exfoliating GNs with the 'printed' borohydrides. These nano-NaBH4@GNs exhibit favorable thermodynamics (decrease in ∆H of ~45%), rapid kinetics (a greater than six-fold increase) and stable de-/re-hydrogenation that retains a high capacity (up to ~5 wt% for NaBH4) compared with those of micro-NaBH4. Our results are helpful in the scalable fabrication of zero-dimensional complex hydrides on two-dimensional supports with enhanced hydrogen storage for potential applications. PMID:27484735

  15. A Guided-Inquiry Approach to the Sodium Borohydride Reduction and Grignard Reaction of Carbonyl Compounds

    Science.gov (United States)

    Rosenberg, Robert E.

    2007-01-01

    The guided-inquiry approach is applied to the reactions of sodium borohydride and phenyl magnesium bromide with benzaldehyde, benzophenone, benzoic anhydride, and ethyl benzoate. Each team of four students receives four unknowns. Students identify the unknowns and their reaction products by using the physical state of the unknown, an…

  16. Platinum-rare earth cathodes for direct borohydride-peroxide fuel cells

    Science.gov (United States)

    Cardoso, D. S. P.; Santos, D. M. F.; Šljukić, B.; Sequeira, C. A. C.; Macciò, D.; Saccone, A.

    2016-03-01

    Hydrogen peroxide (H2O2) is being actively investigated as an oxidant for direct borohydride fuel cells. Herein, platinum-rare earth (RE = Sm, Dy, Ho) alloys are prepared by arc melting and their activity for hydrogen peroxide reduction reaction (HPRR) is studied in alkaline media. Cyclic voltammetry and chronoamperometry measurements show that Pt-Sm electrode displays the highest catalytic activity for HPRR with the lowest activation energy, followed by Pt-Ho, while Pt-Dy alloys show practically no activity. Laboratory direct borohydride-peroxide fuel cells (DBPFCs) are assembled using these alloys. The DBPFC with Pt-Sm cathode gives the highest peak power density of 85 mW cm-2, which is more than double of that obtained in a DBPFC with Pt electrodes.

  17. Structure and spectroscopy of CuH prepared via borohydride reduction.

    Science.gov (United States)

    Bennett, Elliot L; Wilson, Thomas; Murphy, Patrick J; Refson, Keith; Hannon, Alex C; Imberti, Silvia; Callear, Samantha K; Chass, Gregory A; Parker, Stewart F

    2015-12-01

    Copper(I) hydride (cuprous hydride, CuH) was the first binary metal hydride to be discovered (in 1844) and is singular in that it is synthesized in solution, at ambient temperature. There are several synthetic paths to CuH, one of which involves reduction of an aqueous solution of CuSO4·5H2O by borohydride ions. The product from this procedure has not been extensively characterized. Using a combination of diffraction methods (X-ray and neutron) and inelastic neutron scattering spectroscopy, we show that the CuH from the borohydride route has the same bulk structure as CuH produced by other routes. Our work shows that the product consists of a core of CuH with a shell of water and that this may be largely replaced by ethanol. This offers the possibility of modifying the properties of CuH produced by aqueous routes. PMID:26634717

  18. Evaluation of anode (electro)catalytic materials for the direct borohydride fuel cell: Methods and benchmarks

    Science.gov (United States)

    Olu, Pierre-Yves; Job, Nathalie; Chatenet, Marian

    2016-09-01

    In this paper, different methods are discussed for the evaluation of the potential of a given catalyst, in view of an application as a direct borohydride fuel cell DBFC anode material. Characterizations results in DBFC configuration are notably analyzed at the light of important experimental variables which influence the performances of the DBFC. However, in many practical DBFC-oriented studies, these various experimental variables prevent one to isolate the influence of the anode catalyst on the cell performances. Thus, the electrochemical three-electrode cell is a widely-employed and useful tool to isolate the DBFC anode catalyst and to investigate its electrocatalytic activity towards the borohydride oxidation reaction (BOR) in the absence of other limitations. This article reviews selected results for different types of catalysts in electrochemical cell containing a sodium borohydride alkaline electrolyte. In particular, propositions of common experimental conditions and benchmarks are given for practical evaluation of the electrocatalytic activity towards the BOR in three-electrode cell configuration. The major issue of gaseous hydrogen generation and escape upon DBFC operation is also addressed through a comprehensive review of various results depending on the anode composition. At last, preliminary concerns are raised about the stability of potential anode catalysts upon DBFC operation.

  19. Batch sodium borohydride hydrolysis systems: Effect of sudden valve opening on hydrogen generation rate

    OpenAIRE

    M. J. F. Ferreira; Coelho, F; Rangel, C. M.; Pinto, A. M. F. R.

    2012-01-01

    A study was undertaken in order to investigate the potential of hydrogen (H 2) generation by hydrolysis of sodium borohydride solution (10 wt% NaBH 4 and 7 wt% NaOH), in batch reactors, operating at moderate pressures (up to #8764;1.2 MPa), in the presence of a powdered nickel-ruthenium based catalyst, reused between 311 and 316 times, to feed on-demand a proton exchange membrane fuel cell. A different approach to the testing of the performance of the batch NaBH 4 hydrolysis system is explore...

  20. Borohydride-reducible components in soluble collagen irradiated with gamma rays in solution

    International Nuclear Information System (INIS)

    Irradiation with 100 krad of gamma rays of neutral-soluble rat skin collagen decreased the content of aldol cross-links by a factor of three, whereas it did not affect the content of allysine. On reduction with tritiated sodium borohydride, five new components were detected showing different stability towards acid and alkali. (author) tetracycline. The results of kinetic and autoradiographic studies and microscopical analysis of bone preparations suggest that stable strontium inhibits the mineralization of newly formed bone tissue without affecting the physicochemical processes related to ion exchange. (author)

  1. Innovative reactor prototype for Hydrogen production in a stationary application using sodium borohydride

    OpenAIRE

    Barbosa, Rui; Ferreira, V.; Silva, D; Condes, J.; Ramos, S.; Amaral, V.; Pinto, A. M. F. R.; Figueiredo, A; Rangel, C. M.

    2011-01-01

    Hydrogen storage has proved to be the greatest obstacle preventing hydrogen from replacing fossil fuels. Hence, a safe, efficient and economical method of storing hydrogen must be available to turn viable a hydrogen economy based on renewable resources [1]. Hydrogen can be stored in chemical hydrides such as sodium borohydride (NaBH4), with large theoretical H2 content of 10,9 wt%. With the aid of catalysts, and at room temperatures, the alkaline hydrolysis of NaBH4 can be enhanced [2]. In th...

  2. Alkali metal – yttrium borohydrides: The link between coordination of small and large rare-earth

    International Nuclear Information System (INIS)

    The system Li–A–Y–BH4 (A=K, Rb, Cs) is found to contain five new compounds and four further ones known from previous work on the homoleptic borohydrides. Crystal structures have been solved and refined from synchrotron X-ray powder diffraction, thermal stability of new compounds have been investigated and ionic conductivity measured for selected samples. Significant coordination flexibility for Y3+ is revealed, which allows the formation of both octahedral frameworks and tetrahedral complex anions with the tetrahydroborate anion BH4 both as a linker and terminal ligand. Bi- and trimetallic cubic double-perovskites c-A3Y(BH4)6 or c-A2LiY(BH4)6 (A=Rb, Cs) form in all the investigated systems, with the exception of the Li–K–Y system. The compounds with the stoichiometry AY(BH4)4 crystallize in all investigated systems with a great variety of structure types which find their analog amongst metal oxides. In-situ formation of a new borohydride – closo-borane is observed during decomposition of all double perovskites. - Graphical abstract: The system Li–A–Y–BH4 (A=K, Rb, Cs) is found to contain five novel compounds and four further ones previously reported. Significant coordination flexibility of Y3+ is revealed, which can be employed to form both octahedral frameworks and tetrahedral complex anions, very different structural topologies. Versatility is also manifested in three different simultaneously occurring coordination modes of borohydrides for one metal cation, as proposed by DFT optimization of the monoclinic KY(BH4)4 structural model observed by powder diffraction. - Highlights: • The system Li-A-Y-BH4 (A=K, Rb, Cs) contains nine compounds in total. • Y3+ forms octahedral frameworks and tetrahedral complex anions. • Bi- and trimetallic double-perovskites crystallize in most systems. • Various AY(BH4)4 crystallize with structure types analogous to metal oxides. • Double-perovskites decompose and form a novel borohydride-closo-borane

  3. A new family of metal borohydride guanidinate complexes: Synthesis, structures and hydrogen-storage properties

    Science.gov (United States)

    Wu, Hui; Zhou, Xiuquan; Rodriguez, Efrain E.; Zhou, Wei; Udovic, Terrence J.; Yildirim, Taner; Rush, John J.

    2016-10-01

    We report on a new class of complex hydrides: borohydride guanidinate complexes (MBH4·nCN3H5, M=Li, Mg, and Ca). They can be prepared via facile solid-state synthesis routes. Their crystal structures were successfully determined using a combination of X-ray diffraction, first-principles calculations and neutron vibrational spectroscopy. Among these compounds, Mg(BH4)2·6CN3H5 is composed of large complex Mg[CN3H5]62+ cations and surrounding BH4- ions, while Ca(BH4)2·2CN3H5 possesses layers of corner-sharing Ca[BH4]4(CN3H5)2 octahedra. Our dehydrogenation results show that ≈10 wt% hydrogen can be released from MBH4·nCN3H5 (M=Li, Mg, and Ca) at moderate temperatures with minimal ammonia and diborane contamination thanks to the synergistic effect of C-N bonds from guanidine and hydridic H from borohydrides leading to a weakening of the N-H bonds, thus impeding ammonia gas liberation. Further tuning the dehydrogenation with different cation species indicates that Mg(BH4)2·nCN3H5 can exhibit the optimum properties with nearly thermally neutral dehydrogenation and very high purity hydrogen release.

  4. Poly (vinyl alcohol) hydrogel membrane as electrolyte for direct borohydride fuel cells

    Indian Academy of Sciences (India)

    N A Choudhury; S K Prashant; S Pitchumani; P Sridhar; A K Shukla

    2009-09-01

    A direct borohydride fuel cell (DBFC) employing a poly (vinyl alcohol) hydrogel membrane electrolyte (PHME) is reported. The DBFC employs an AB5 Misch metal alloy as anode and a goldplated stainless steel mesh as cathode in conjunction with aqueous alkaline solution of sodium borohydride as fuel and aqueous acidified solution of hydrogen peroxide as oxidant. Room temperature performances of the PHME-based DBFC in respect of peak power outputs; ex-situ cross-over of oxidant, fuel, anolyte and catholyte across the membrane electrolytes; utilization efficiencies of fuel and oxidant, as also cell performance durability are compared with a similar DBFC employing a Nafion®-117 membrane electrolyte (NME). Peak power densities of ∼30 and ∼40 mW cm-2 are observed for the DBFCs with PHME and NME, respectively. The crossover of NaBH4 across both the membranes has been found to be very low. The utilization efficiencies of NaBH4 and H2O2 are found to be ∼24 and ∼59%, respectively for the PHME-based DBFC; ∼18 and ∼62%, respectively for the NME-based DBFC. The PHME and NME-based DBFCs exhibit operational cell potentials of ∼ 1.2 and ∼ 1.4 V, respectively at a load current density of 10 mA cm-2 for ∼100 h.

  5. Solid-state Asymmetric Reduction of (S)-1, l'-Bi-2-naphtholAcetylferrocene Molecular Compound with Sodium Borohydride

    Institute of Scientific and Technical Information of China (English)

    MENG, Ji-Ben; DU, Hai-Feng; DING, Kui-Ling

    2001-01-01

    A novel molecular crystal formed between enanteopure 1,l'bi-2-naphthoi and acetylferrocene has been prepared andcharacterized in this communication. The examination on itsreducton with soditma borohydride showed that the asymnetric inducton was observed in the solid state but not in the solution phase. The asymmetric induction in the solid-state reaction may be attributed to the chiral microenviromnent ofmolecular crystal.

  6. Density functional theory based screening of ternary alkali-transition metal borohydrides: A computational material design project

    DEFF Research Database (Denmark)

    Hummelshøj, Jens Strabo; Landis, David; Voss, Johannes;

    2009-01-01

    We present a computational screening study of ternary metal borohydrides for reversible hydrogen storage based on density functional theory. We investigate the stability and decomposition of alloys containing 1 alkali metal atom, Li, Na, or K (M1); and 1 alkali, alkaline earth or 3d/4d transition...

  7. Rare earth metal oxides as BH4-tolerance cathode electrocatalysts for direct borohydride fuel cells

    Institute of Scientific and Technical Information of China (English)

    NI Xuemin; WANG Yadong; GUO Feng; YAO Pei; PAN Mu

    2012-01-01

    Rare earth metal oxides (REMO) as cathode electrocatalysts in direct borohydride fuel cell (DBFC) were investigated.The REMO electrocatalysts tested showed favorable activity to the oxygen electro-reduction reaction and strong tolerance to the attack of BH4- in alkaline electrolytes.The simple membraneless DBFCs using REMO as cathode electrocatalyst and using hydrogen storage alloy as anodic electrocatalyst exhibited an open circuit of about 1 V and peak power of above 60 mW/cm2.The DBFC using Sm2O3 as cathode electrocatalyst showed a relatively better performance.The maximal power density of 76.2 mW/cm2 was obtained at the cell voltage of 0.52 V.

  8. Durability and reutilization capabilities of a Ni-Ru catalyst for the hydrolysis of sodium borohydride in batch reactors

    OpenAIRE

    Pinto, A.M.F.R.; M.J.F. Ferreira; Fernandes, V. R.; Rangel, C. M.

    2011-01-01

    The study of catalyst durability and reutilization on catalyzed hydrolysis of sodium borohydride is essential from an application point of view. Few works on this topic are available in the literature. In the present work, a powder nickel-ruthenium based catalyst, unsupported, used in two different schemes of NaBH 4 hydrolysis (alkaline and alkali free hydrolysis), performed in batch reactors with different volumes and bottom geometries (flat and conical), was investigated in terms of durabil...

  9. Nuclear magnetic resonance studies of atomic motion in borohydride-based materials: Fast anion reorientations and cation diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Skripov, A.V., E-mail: skripov@imp.uran.ru; Soloninin, A.V.; Babanova, O.A.; Skoryunov, R.V.

    2015-10-05

    Highlights: • Solid solutions LiBH{sub 4}–LiI: extremely fast BH{sub 4} reorientations down to low T. • LiLa(BH{sub 4}){sub 3}Cl: Li-ion diffusive jumps and BH{sub 4} reorientations at the same frequency scale. • Dramatic acceleration of B{sub 12}H{sub 12} reorientations in the disordered phase of Na{sub 2}B{sub 12}H{sub 12}. • Fast Na-ion diffusion in the disordered phase of Na{sub 2}B{sub 12}H{sub 12}. - Abstract: Two basic types of thermally activated atomic jump motion are known to exist in solid borohydrides and the related systems: the reorientations of complex anions ([BH{sub 4}]{sup −}, [B{sub 12}H{sub 12}]{sup 2−}) and the translational diffusion of metal cations or complex anions. This paper reviews recent progress in nuclear magnetic resonance (NMR) studies of these jump processes in complex hydrides, such as solid solutions of halide anions in borohydrides, bimetallic borohydrides and borohydride–chlorides, borohydride–amides, and B{sub 12}H{sub 12}-based compounds. The emphasis is put on the systems showing fast-ion conductivity. For these systems, we discuss a possible relation between the reorientational motion of complex anions and the translational motion of metal cations.

  10. Probing molecular dynamics of metal borohydrides on the surface of mesoporous scaffolds by multinuclear high resolution solid state NMR

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Son-Jong, E-mail: Sonjong@cheme.caltech.edu [Division of Chemistry and Chemical Eng., California Institute of Technology, Pasadena, CA 91125 (United States); Lee, Hyun-Sook [High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); To, Magnus [Division of Chemistry and Chemical Eng., California Institute of Technology, Pasadena, CA 91125 (United States); Lee, Young-Su; Cho, Young Whan [High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Choi, Hyungkeun; Kim, Chul [Department of Chemistry, Hannam University, Daejeon 305-811 (Korea, Republic of)

    2015-10-05

    Graphical abstract: In situ variable temperature multinuclear solid state NMR allows to probe surface wetting, diffusivity, and confinement of metal borohydrides into nanopores. - Abstract: Understanding of surface interactions between borohydride molecules and the surfaces of porous supports have gained growing attention for successful development of nano-confinement engineering. By use of in situ variable temperature (VT) magic angle spinning (MAS) NMR, molecular mobility changes of LiBH{sub 4} crystalline solid has been investigated in the presence of silica based and carbonaceous surfaces. Spin–spin J-coupling of {sup 1}H–{sup 11}B in LiBH{sub 4} was monitored in series of VT NMR spectra to probe translational mobility of LiBH{sub 4} that appeared to be greatly enhanced upon surface contact. Such enhanced diffusivity was found to be effective in the formation of solid solution and co-confinement with other metal borohydrides. Co-confinement of LiBH{sub 4}–Ca(BH{sub 4}){sub 2} mixture was demonstrated at temperature as low as 100 °C, much lower than the reported bulk eutectic melting temperature. The discovery adds a novel property of LiBH{sub 4} that has been proven to be highly versatile in many energy related applications.

  11. Reductive reactivity of borohydride- and dithionite-synthesized iron-based nanoparticles: A comparative study.

    Science.gov (United States)

    Ma, Xiaoming; He, Di; Jones, Adele M; Collins, Richard N; Waite, T David

    2016-02-13

    In this study sodium dithionite (NaS2O4) and sodium borohydride (NaBH4) were employed as reducing agents for the synthesis of nanosized iron-based particles. The particles formed using NaBH4 (denoted nFe(BH4)) principally contained (as expected) Fe(0) according to XAS and XRD analyses while the particles synthesized using NaS2O4, (denoted nFe(S2O4)) were dominated by the mixed Fe(II)/Fe(III) mineral magnetite (Fe3O4) though with possible presence of Fe(0). The ability of both particles to reduce trichloroethylene (TCE) under analogous conditions demonstrated remarkable differences with nFe(BH4) resulting in complete reduction of 1.5mM of TCE in 2h while nFe(S2O4) were unable to effect complete reduction of TCE in 120 h. Moreover, acetylene was the major reaction product formed in the presence of nFe(S2O4) while the major reaction product formed following reaction with nFe(BH4) was ethylene, which was further reduced to ethane as the reaction proceeded. Considering that effective Pd reduction to Pd(0) requires the presence of Fe(0), this is consistent with our finding that Fe(0) is not the dominant phase formed when employing dithionite as a reducing agent under the conditions employed in this study. PMID:26513569

  12. Hydrogen generation from methanolysis of sodium borohydride over Co/Al2O3 catalyst

    Institute of Scientific and Technical Information of China (English)

    Dongyan Xu; Lin Zhao; Ping Dai; Shengfu Ji

    2012-01-01

    Co/Al2O3 catalyst is prepared with an impregnation-chemical reduction method and used to catalyze the methanolysis of sodium borohydride (NaBH4) for hydrogen generation.At solution temperature of 0℃,the methanolysis reaction can be effectively accelerated using Co/Al2O3 catalyst and provide a desirable hydrogen generation rate,which makes it suitable for apphcations under the circumstance of low environmental temperature.The byproduct of methanolysis reaction is analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR).The characterization results indicate that methanol can be easily recovered after methanolysis reaction by hydrolysis of the methanolysis byproduct,NaB(OCH3)4.The catalytic activity of Co/Al2O3 towards NaBH4 methanolysis can be further improved by appropriate calcination treatment.The catalytic methanolysis kinetics and catalyst reusability are also studied over the Co/Al2O3 catalyst calcined at the optimized temperature.

  13. Formation of borohydride-reduced nickel-boron coatings on various steel substrates

    Science.gov (United States)

    Vitry, V.; Delaunois, F.

    2015-12-01

    Electroless nickel-boron coatings are widely used in industrial on various substrates: ferrous and non-ferrous alloys mainly but also in some cases non-metallic materials. However, their growth process is still not fully understood and the influence of the nature of the substrate on this process is completely unknown. The formation of electroless nickel-boron was observed on five ferrous alloys: a mild steel, a high carbon unalloyed steel, a cryogenic steel (that contains 9 wt.% nickel), an austenitic stainless steel and an austeno-ferritic (duplex) stainless steel. Nickel-boron films were prepared by electroless deposition, using sodium borohydride as a reducing agent. Samples were immersed in a plating bath for times ranging from 5 s to 60 min. The influence of the nature of the substrate on the initial deposition of the coatings was investigated in detail: the initiation mechanism was identified for all substrates and it was found to be related to catalytic oxidation of the reducing agent rather than to a displacement process. The delay before initiation was influenced by the nickel content of the coating and by a high number of grain boundaries. In all cases, the plating rate varied with plating time, with a slower period during the first 10 min that corresponds to morphological modification of the coating.

  14. Structure determination of ultra dense magnesium borohydride: A first-principles study

    Science.gov (United States)

    Fan, Jing; Duan, Defang; Jin, Xilian; Bao, Kuo; Liu, Bingbing; Cui, Tian

    2013-06-01

    Magnesium borohydride (Mg(BH4)2) is one of the potential hydrogen storage materials. Recently, two experiments [Y. Filinchuk, B. Richter, T. R. Jensen, V. Dmitriev, D. Chernyshov, and H. Hagemann, Angew. Chem., Int. Ed. 50, 11162 (2011);, 10.1002/anie.201100675 L. George, V. Drozd, and S. K. Saxena, J. Phys. Chem. C 113, 486 (2009), 10.1021/jp807842t] found that α-Mg(BH4)2 can irreversibly be transformed to an ultra dense δ-Mg(BH4)2 under high pressure. Its volumetric hydrogen content at ambient pressure (147 g/cm3) exceeds twice of DOE's (U.S. Department of Energy) target (70 g/cm3) and that of α-Mg(BH4)2 (117 g/cm3) by 20%. In this study, the experimentally proposed P42nm structure of δ-phase has been found to be dynamically unstable. A new Fddd structure has been reported as a good candidate of δ-phase instead. Its enthalpy from 0 to 12 GPa is much lower than P42nm structure and the simulated X-ray diffraction spectrum is in satisfied agreement with previous experiments. In addition, the previously proposed P-3m1 structure, which is denser than Fddd, is found to be a candidate of ɛ-phase due to the agreement of Raman shifts.

  15. An extremely rapid, convenient and mild coal desulfurization new process: Sodium borohydride reduction

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhiling; Sun, Tonghua; Jia, Jinping [School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)

    2010-09-15

    The present work describes the desulfurization of coal using mildly reductive method. Both a Yanzhou and a Yanshan coal (referred to as YZ and YS coal, respectively), were treated in an aqueous media employing sodium borohydride (NaBH{sub 4}) as reducing agent, which is a well known hydrogen storage. Reaction variables investigated include concentration of reductant, time, pH of initial media, temperature, stirring rate and particle size. The calorific values and ignition temperatures of the coal samples before and after treatment were determined. Results show that the total sulfur removal improved with the increase in the concentration of NaBH{sub 4}, shaking rate and temperature and with the decrease in the particle size. Meanwhile, decreasing the particle size from - 250 to - 109 {mu}m increased the organic sulfur removal by more than six times for either of the coal samples. Considering economic rationality and operational convenience, the desulfurization conditions determined were 1.6 mM of NaBH{sub 4} concentration, - 109 {mu}m of particle size, neutral pH of initial media, 1 min of treated time, 100 rpm of shaking rate, 30 C of temperature. This led to 23.8% and 59.0% reduction in the pyritic, 70.4% and 100% reduction in the sulfate, and 11.0% and 15.0% reduction in the organic sulfur, giving 31.3% and 40.8% reduction in the total sulfur for the YZ coal and the YS coal, respectively. Moreover, this resulted in the increase in the calorific values by 3.4-6.9% and the decrease in the ignition temperatures by 2-21 C for the coal samples. The desulfurization method described here is extremely rapid, convenient, inexpensive and mild, and therefore, has considerable technological interest. (author)

  16. Alkali free hydrolysis of sodium borohydride for hydrogen generation under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, M.J.F.; Pinto, A.M.F.R. [Centro de Estudos de Fenomenos de Transporte, Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias s/n, 4200-465 Porto (Portugal); Gales, L. [Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto and Instituto de Ciencias Biomedicas Abel Salazar, Largo Prof. Abel Salazar 2, 4099-003 Porto (Portugal); Fernandes, V.R.; Rangel, C.M. [Laboratorio Nacional de Energia e Geologia - LNEG, Fuel Cells and Hydrogen Unit Estrada do Paco do Lumiar 22, 1649-038 Lisboa (Portugal)

    2010-09-15

    The present study is related with the production of hydrogen gas (H{sub 2}), at elevated pressures and with high gravimetric storage density, to supply a PEM fuel cell on-demand. To achieve this goal, solid sodium borohydride (NaBH{sub 4}) was mixed with a proper amount of a powder reused nickel-ruthenium based catalyst (Ni-Ru based/NaBH{sub 4}: 0.2 and 0.4 g/g; {approx}150 times reused) inside the bottom of a batch reactor. Then, a stoichiometric amount of pure liquid water (H{sub 2}O/NaBH{sub 4}: 2-8 mol/mol) was added and the catalyzed NaBH{sub 4} hydrolysis evolved, in the absence of an alkali inhibitor. In this way, this research work is designated alkali free hydrolysis of NaBH{sub 4} for H{sub 2} generation. This type of hydrolysis is excellent from an environmental point of view because it does not involve strongly caustic solutions. Experiments were performed in three batch reactors with internal volumes 646, 369 and 229 cm{sup 3}, and having different bottom geometries (flat and conical shapes). The H{sub 2} generated was a function of the added water and completion was achieved with H{sub 2}O/NaBH{sub 4} = 8 mol/mol. The results show that hydrogen yields and rates increase remarkably increasing both system temperature and pressure. Reactor bottom shape influences deeply H{sub 2} generation: the conical bottom shape greatly enhances the rate and practically eliminates the reaction induction time. Our system of compressed hydrogen generation up to 1.26 MPa shows 6.3 wt% and 70 kg m{sup -3}, respectively, for gravimetric and volumetric hydrogen storage capacities (materials-only basis) and therefore is a viable hydrogen storage candidate for portable applications. (author)

  17. AB5-type Hydrogen Storage Alloy Modified with Ti/Zr Used as Anodic Materials in Borohydride Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    Lianbang WANG; Chunan MA; Xinbiao MAO; Yuanming SUN; Seijiro SUDA

    2005-01-01

    Fuel cell using borohydride as the fuel has received much attention. AB5-type hydrogen storage alloy used as the anodic material instead of noble metals has been investigated. In order to restrain the generation of hydrogen and enhance the utilization of borohydride, Ti/Zr metal powders has been added into the parent LmNi4.78Mn0.22 (where Lm is La-richened mischmetal) alloy (LNM) by ball milling and heat treatment methods. It is found that the addition of Ti/Zr metal powders lowers the electrochemical catalytic activity of the electrodes, at the same time, restrains the generation of hydrogen and enhances the utilization of the fuel. All the results show that the hydrogen generation rate or the utilization of the fuel is directly relative to the electrochemical catalytic activity or the discharge capability of the electrodes. The utilization of the fuel increases with discharge current density. It is very important to find a balance between the discharge capability and the utilization of the fuel.

  18. Improving SERS Detection of Bacillus thuringiensis Using Silver Nanoparticles Reduced with Hydroxylamine and with Citrate Capped Borohydride

    International Nuclear Information System (INIS)

    The development of techniques that could be useful in fields other than biological warfare agents countermeasures such as medical diagnostics, industrial microbiology, and environmental applications have become a very important subject of research. Raman spectroscopy can be used in near field or at long distances from the sample to obtain fingerprinting information of chemical composition of microorganisms. In this research, biochemical components of the cell wall and endospores of Bacillus thuringiensis (Bt) were identified by surface-enhanced Raman scattering (SERS) spectroscopy using silver (Ag) nanoparticles (NPs) reduced by hydroxylamine and borohydride capped with sodium citrate. Activation of hot spots, aggregation and surface charge modification of the NPs, was studied and optimized to obtain signal enhancements from Bt by SERS. Slight aggregation of the NPs as well as surface charge modification to a more acidic ambient was induced using small-size borohydride-reduced NPs in the form of metallic suspensions aimed at increasing the Ag NP-Bt interactions. Hydroxylamine-reduced NPs required slight aggregation and no pH modifications in order to obtain high spectral quality results in bringing out SERS signatures of Bt.

  19. Carbon-supported Pt0.75M0.25 (M = Ni or Co) electrocatalysts for borohydride oxidation

    International Nuclear Information System (INIS)

    Highlights: • BH4− electrooxidation at carbon supported Pt-alloys (Pt0.75M0.25/C, M = Ni or Co). • Influence of BH4− concentration and temperature on BH4− electrooxidation. • Evaluation of charge transfer coefficients and number of electrons exchanged. • Assessment of heterogeneous rate constants and activation energies. • Higher catalytic activity of Pt0.75M0.25/C than Pt/C for BH4− electrooxidation. -- Abstract: Electrochemical oxidation of sodium borohydride (NaBH4) at carbon-supported platinum (Pt/C) and carbon-supported bimetallic platinum alloys (Pt0.75M0.25/C, with M = Ni or Co) is studied in alkaline media using cyclic voltammetry and linear scan voltammetry with rotating disc electrode. Main kinetic parameters (e.g., charge transfer coefficients, number of electrons exchanged, standard heterogeneous rate constants and activation energies) for NaBH4 oxidation on these electrocatalysts are determined. Results indicate the highest catalytic activity of Pt0.75Ni0.25/C alloy electrocatalyst, followed by Pt0.75Co0.25/C, while the lowest activity is observed for Pt/C electrocatalyst. The influence of electrolyte composition and temperature on NaBH4 electrooxidation at the three materials is also explored. The good performance of these bimetallic alloys makes them a lower cost alternative to single Pt as electrocatalysts for the direct borohydride fuel cell anode

  20. Study of the ultrafast polarization dynamics in lithium borohydride by means of femtosecond X-ray diffraction

    International Nuclear Information System (INIS)

    In this thesis the ultrafast electronic polarisation in the crystalline material lithium borohydride (LiBH4) is examined. The material is excited by a femtosecond long optical pulse and scanned by a likewise short X-ray pulse. Using X-ray scattering the optically induced spatial rearrangement of electronic charge can be directly mapped with atomic spatial resolution. Copper K-alpha X-rays for the experiment are produced in a laboratory table-top laserplasma source with 1 kHz repetition rate. This radiation is then focused on a powdered sample. Debye-Scherrer rings produced from powder diffraction are collected on a large area detector and processed to yield intensity profiles. Using pump-probe technique the change in diffracted intensity, triggered by excitation with a femtosecond optical pulse is examined. The temporal resolution is given by the delay between pump and probe pulse. This way insight is gained into the dynamic electronic evolution of the system. Intensity changes can be correlated to changes in charge density in the relevant material to elucidate structural dynamics on the femtosecond time scale. Lithium borohydride was chosen since it displays necessary characteristics for the exploration of ultrafast electronic polarisation. Up to date there has been no spatially resolved research in the femtosecond regime elucidating this electronic phenomenon. This work presents the ultrafast resonse in Lithiumborhydrid (LiBH4) to strong electronic fields with optical frequencies, which leads to charge relocation accompanied by electronic polarisation.

  1. Zeolite-confined ruthenium(0) nanoclusters catalyst: record catalytic activity, reusability, and lifetime in hydrogen generation from the hydrolysis of sodium borohydride.

    Science.gov (United States)

    Zahmakiran, Mehmet; Ozkar, Saim

    2009-03-01

    Sodium borohydride, NaBH4, has been considered the most attractive hydrogen-storage material for portable fuel cell applications, as it provides a safe and practical means of producing hydrogen. In a recent communication (Zahmakiran, M.; Ozkar, S. Langmuir 2008, 24, 7065), we have reported a record total turnover number (TTON) of 103 200 mol H2/mol Ru and turnover frequency (TOF) up to 33 000 mol H2/mol Ru x h obtained by using intrazeolite ruthenium(0) nanoclusters in the hydrolysis of sodium borohydride. Here we report full details of the kinetic studies on the intrazeolite ruthenium(0) nanoclusters catalyzed hydrolysis of sodium borohydride in both aqueous and basic solutions. Expectedly, the intrazeolite ruthenium(0) nanoclusters show unprecedented catalytic lifetime, TTON = 27 200 mol H2/mol Ru, and TOF up to 4000 mol H2/mol Ru x h in the hydrolysis of sodium borohydride in basic solution (5% wt NaOH) as well. More importantly, the intrazeolite ruthenium(0) nanoclusters are isolable, bottleable, redispersible, and yet catalytically active. They retain 76% or 61% of their initial catalytic activity at the fifth run with a complete release of hydrogen in aqueous and basic medium, respectively. The intrazeolite ruthenium(0) nanoclusters were isolated as black powder and characterized by using a combination of advanced analytical techniques including XRD, HRTEM, TEM-EDX, SEM, XPS, ICP-OES, and N2 adsorption. PMID:19437749

  2. Temperature-mediated phase transformation, pore geometry and pore hysteresis transformation of borohydride derived in-born porous zirconium hydroxide nanopowders

    Science.gov (United States)

    Nayak, Nadiya B.; Nayak, Bibhuti B.

    2016-05-01

    Development of in-born porous nature of zirconium hydroxide nanopowders through a facile hydrogen (H2) gas-bubbles assisted borohydride synthesis route using sodium borohydride (NaBH4) and novel information on the temperature-mediated phase transformation, pore geometry as well as pore hysteresis transformation of in-born porous zirconium hydroxide nanopowders with the help of X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) isotherm and Transmission Electron Microscopy (TEM) images are the main theme of this research work. Without any surfactants or pore forming agents, the borohydride derived amorphous nature of porous powders was stable up to 500 °C and then the seed crystals start to develop within the loose amorphous matrix and trapping the inter-particulate voids, which led to develop the porous nature of tetragonal zirconium oxide at 600 °C and further sustain this porous nature as well as tetragonal phase of zirconium oxide up to 800 °C. The novel hydrogen (H2) gas-bubbles assisted borohydride synthesis route led to develop thermally stable porous zirconium hydroxide/oxide nanopowders with an adequate pore size, pore volume, and surface area and thus these porous materials are further suggested for promising use in different areas of applications.

  3. Organic derivatives of Mg(BH4)2 as precursors towards MgB2 and novel inorganic mixed-cation borohydrides.

    Science.gov (United States)

    Wegner, W; Jaroń, T; Dobrowolski, M A; Dobrzycki, Ł; Cyrański, M K; Grochala, W

    2016-09-28

    A series of organic derivatives of magnesium borohydride, including Mg(BH4)2·1.5DME (DME = 1,2-dimethoxyethane) and Mg(BH4)2·3THF (THF = tetrahydrofuran) solvates and three mixed-cation borohydrides, [Cat]2[Mg(BH4)4], [Cat] = [Me4N], [nBu4N], [Ph4P], have been characterized. The phosphonium derivative has been tested as a precursor for synthesis of inorganic mixed-metal borohydrides of magnesium, Mx[Mg(BH4)2+x], M = Li-Cs, via a metathetic method. The synthetic procedure has yielded two new derivatives of heavier alkali metals M3Mg(BH4)5 (M = Rb, Cs) mixed with amorphous Mg(BH4)2. Thermal decomposition has been studied for both the organic and inorganic magnesium borohydride derivatives. Amorphous MgB2 has been detected among the products of the thermal decomposition of the solvates studied, together with organic and inorganic impurities.

  4. Electronic structure of nickel(II) and zinc(II) borohydrides from spectroscopic measurements and computational modeling.

    Science.gov (United States)

    Desrochers, Patrick J; Sutton, Christopher A; Abrams, Micah L; Ye, Shengfa; Neese, Frank; Telser, Joshua; Ozarowski, Andrew; Krzystek, J

    2012-03-01

    The previously reported Ni(II) complex, Tp*Ni(κ(3)-BH(4)) (Tp* = hydrotris(3,5-dimethylpyrazolyl)borate anion), which has an S = 1 spin ground state, was studied by high-frequency and -field electron paramagnetic resonance (HFEPR) spectroscopy as a solid powder at low temperature, by UV-vis-NIR spectroscopy in the solid state and in solution at room temperature, and by paramagnetic (11)B NMR. HFEPR provided its spin Hamiltonian parameters: D = 1.91(1) cm(-1), E = 0.285(8) cm(-1), g = [2.170(4), 2.161(3), 2.133(3)]. Similar, but not identical parameters were obtained for its borodeuteride analogue. The previously unreported complex, Tp*Zn(κ(2)-BH(4)), was prepared, and IR and NMR spectroscopy allowed its comparison with analogous closed shell borohydride complexes. Ligand-field theory was used to model the electronic transitions in the Ni(II) complex successfully, although it was less successful at reproducing the zero-field splitting (zfs) parameters. Advanced computational methods, both density functional theory (DFT) and ab initio wave function based approaches, were applied to these Tp*MBH(4) complexes to better understand the interaction between these metals and borohydride ion. DFT successfully reproduced bonding geometries and vibrational behavior of the complexes, although it was less successful for the spin Hamiltonian parameters of the open shell Ni(II) complex. These were instead best described using ab initio methods. The origin of the zfs in Tp*Ni(κ(3)-BH(4)) is described and shows that the relatively small magnitude of D results from several spin-orbit coupling (SOC) interactions of large magnitude, but with opposite sign. Spin-spin coupling (SSC) is also shown to be significant, a point that is not always appreciated in transition metal complexes. Overall, a picture of bonding and electronic structure in open and closed shell late transition metal borohydrides is provided, which has implications for the use of these complexes in catalysis and

  5. Carbon supported Cu-Pd nanoparticles as anode catalyst for direct borohydride-hydrogen peroxide fuel cells

    International Nuclear Information System (INIS)

    Carbon supported Cu-Pd bimetallic nanoparticles were prepared by a successive reduction method in aqueous solution and used as anode electrocatalyst for direct borohydride-hydrogen peroxide fuel cell (DBHFC). The physical and electrochemical properties of the as-prepared electrocatalysts are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), cyclic voltammetry (CV), chronopotentiometry (CP), linear sweep voltammetry (LSV) and fuel cell test. The results show that the size of the crystallite is around 12.5 nm, the Cu1Pd1/C catalyst presents the highest catalytic activity among all the resultant catalysts, and the DBHFC using Cu1Pd1/C as anode catalyst and Pt mesh (1 cm × 1 cm) as cathode electrode obtains the maximum power density as high as 39.8 mW cm-2 at a discharge current density of 80.1 mA cm-2 at 20 °C

  6. Alkaline sodium borohydride gel as a hydrogen source for PEMFC or an energy carrier for NaBH 4-air battery

    Science.gov (United States)

    Liu, B. H.; Li, Z. P.; Chen, L. L.

    In this preliminary study, we tried to use sodium polyacrylate as the super absorbent polymer to form alkaline NaBH 4 gel and explored its possibilities for borohydride hydrolysis and borohydride electro-oxidation. It was found that the absorption capacity of sodium polyacrylate decreased with increasing NaBH 4 concentration. The formed gel was rather stable in the sealed vessel but tended to slowly decompose in open air. Hydrogen generation from the gel was carried out using CoCl 2 catalyst precursor solutions. Hydrogen generation rate from the alkaline NaBH 4 gel was found to be higher and impurities in hydrogen were less than that from the alkaline NaBH 4 solution. The NaBH 4 gel also successfully powered a NaBH 4-air battery.

  7. Alkaline sodium borohydride gel as a hydrogen source for PEMFC or an energy carrier for NaBH{sub 4}-air battery

    Energy Technology Data Exchange (ETDEWEB)

    Liu, B.H. [Department of Materials and Engineering, Zhejiang University (China); Li, Z.P.; Chen, L.L. [Department of Chemical and Biochemical Engineering, Zhejiang University, Hangzhou 310027 (China)

    2008-05-15

    In this preliminary study, we tried to use sodium polyacrylate as the super absorbent polymer to form alkaline NaBH{sub 4} gel and explored its possibilities for borohydride hydrolysis and borohydride electro-oxidation. It was found that the absorption capacity of sodium polyacrylate decreased with increasing NaBH{sub 4} concentration. The formed gel was rather stable in the sealed vessel but tended to slowly decompose in open air. Hydrogen generation from the gel was carried out using CoCl{sub 2} catalyst precursor solutions. Hydrogen generation rate from the alkaline NaBH{sub 4} gel was found to be higher and impurities in hydrogen were less than that from the alkaline NaBH{sub 4} solution. The NaBH{sub 4} gel also successfully powered a NaBH{sub 4}-air battery. (author)

  8. Hydrogen generation from catalytic hydrolysis of sodium borohydride solution using Cobalt-Copper-Boride (Co-Cu-B) catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Xin-Long; Yuan, Xianxia; Jia, Chao; Ma, Zi-Feng [Department of Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2010-10-15

    Co-Cu-B, as a catalyst toward hydrolysis of sodium borohydride solution, has been prepared through chemical reduction of metal salts, CoCl{sub 2}.6H{sub 2}O and CuCl{sub 2}, by an alkaline solution composed of 7.5wt% NaBH{sub 4} and 7.5wt% NaOH. The effects of Co/Cu molar ratio, calcination temperature, NaOH and NaBH{sub 4} concentration and reaction temperature on catalytic activity of Co-Cu-B for hydrogen generation from alkaline NaBH{sub 4} solution have been studied. X-ray diffraction (XRD), scanning electron microscope (SEM) and Nitrogen adsorption-desorption isotherm have been employed to understand the results. The Co-Cu-B catalyst with a Co/Cu molar ratio of 3:1 and calcinated at 400 C showed the best catalytic activity at ambient temperature. The activation energy of this catalytic reaction is calculated to be 49.6 kJ mol{sup -1}. (author)

  9. Combined X-ray and Raman Studies on the Effect of Cobalt Additives on the Decomposition of Magnesium Borohydride

    Directory of Open Access Journals (Sweden)

    Olena Zavorotynska

    2015-08-01

    Full Text Available Magnesium borohydride (Mg(BH42 is one of the most promising hydrogen storage materials. Its kinetics of hydrogen desorption, reversibility, and complex reaction pathways during decomposition and rehydrogenation, however, present a challenge, which has been often addressed by using transition metal compounds as additives. In this work the decomposition of Mg(BH42 ball-milled with CoCl2 and CoF2 additives, was studied by means of a combination of several in-situ techniques. Synchrotron X-ray diffraction and Raman spectroscopy were used to follow the phase transitions and decomposition of Mg(BH42. By comparison with pure milled Mg(BH42, the temperature for the γ → ε phase transition in the samples with CoF2 or CoCl2 additives was reduced by 10–45 °C. In-situ Raman measurements showed the formation of a decomposition phase with vibrations at 2513, 2411 and 766 cm−1 in the sample with CoF2. Simultaneous X-ray absorption measurements at the Co K-edge revealed that the additives chemically transformed to other species. CoF2 slowly reacted upon heating till ~290 °C, whereas CoCl2 transformed drastically at ~180 °C.

  10. Cold-starting portable microenergy system. Autonomous fuel cell system using sodium borohydride as an energy source; Kaltstartfaehiges portables Mikroenergiesystem. Autarkes BZ-System mit Natriumborhydrid als Energietraeger

    Energy Technology Data Exchange (ETDEWEB)

    Groos, Ulf; Koch, Wolfgang [Fraunhofer-Institut fuer Solare Energiesysteme (ISE), Freiburg im Breisgau (Germany)

    2012-10-15

    A project consortium led by Fraunhofer-Institut fuer Solare Energiesysteme ISE developed an autonomous micro energy system (AMES) with an output of 100 W{sub el} as a charging station for applications in emergency medicine. The system is designed for a wide temperature range of -15 to +50 degC during startup, operation, and shutoff. The cold starting fuel cell system is in accordance with current standards and is suited for serial production. It can be operated with common hydrogen stores, e.g. gas flasks or metal hydrides, or else with a specially developed hydrogen generator based on sodium borohydride. (orig.)

  11. First One-step Enantioselective Reduction of á-Haloacetophenones into Styrene Oxides using Sodium Borohydride in Water

    Institute of Scientific and Technical Information of China (English)

    LI Jing-wei; XU Li-wen; XIA Chun-gu

    2004-01-01

    The synthesis of enantiomerically enriched epoxides especially styrene oxides is an interesting challenge1,2 since they are often valuable building blocks for various fine chemical products and pharmaceuticals such as (a)2-, (a)3-, and á1-adrenergic receptor agonists3, 4. In recent years,there has been a flood of papers describing the synthetical methods of the chiral non-racemic epoxides5,6. Here we firstly developed a green, simple and potential epoxidation system by enantioselective reduction of a-haloacetophenones using NaBH4 in water.The procedure of the unexpected epoxidation was firstly found accidentally in the study of L-proline-catalyzed asymmetric reduction of aldehydes, ketones in water. In that time, we observed not only reductive product a-bromophenethyl alcohol but also a small quantity of styrene oxide after three hour reduction of a-bromoacephenone in water. It is impossible to produce the epoxide in the reduction when THF acts as solvent. Then we optimized the reaction conditions and extended reaction time to 5 hr until we obtained the epoxide as a major product.Encouraged by the front results, we tried a-CD as a chiral inducement and catalyst. Cyclodextrins (CDs), a cyclic oligosaccharide composed of several D-glucose units with an a-1, 4 linkage (6, 7, 8for á-, (a)-, (a)-CD, respectively), have been recognized as versatile enzyme mimics since every one molecule of them possesses a hydrophilic outside, which can dissolve in water, and a hydrophobic cavity, which provides an apolar matrix, described as "micro heterogeneous enwronment"7. All the experiments were carried out in water under room temperature. The procedure is a green, simple and potential, although the optically active styrene oxides are obtained in only moderate ees. and yields.When á-bromoacephenone and Sodium Borohydride (1.2 equiv, to ketone) reacts in water using 150mol% (a)-CD as catalyst, a 41% chemical yield and 45% optical yield of the corresponding epoxide were obtained

  12. RING-OPENING POLYMERIZAION OF 2,2-DIMETHYLTRIMETHYLENE CARBONATE INITIATED BY IN SITU GENERATED, TETRAHYDROSALEN STABLIZED YTTRIUM BOROHYDRIDE COMPLEX AND RANDOM COPOLYMERIZATION WITH ε-CAPROLACTONE

    Institute of Scientific and Technical Information of China (English)

    Jing Huang; Jian-fang Yu; Han-jian Yu; Wei-lin Sun; Zhi-quan Shen

    2011-01-01

    The poly(2,2-dimethyltrimethylene carbonate) (PDTC) with one hydroxyl and one formate tenninal fimctions was synthesized by in situ generated, tetrahydrosalen stabilized yttrium borohydride complex. The influences of monomer/initiator molar ratio, temperature and reaction time on polymerization of DTC were investigated. Under the condition: [DTC]/[I] = 500, 55℃, toluene: 0.5 mL, DTC: 0.6 g, PDTC with Mn = 15600 and PDI = 2.15 was obtained.Through 1H-NMR and 13C-NMR analyses, the structure of PDTC was characterized and a coordination-insertion mechanism was proposed. In addition, the random copolymerization of DTC and caprolactone (CL) initiated by rare-earth borohydride compound was studied. The microstructure of PDTC-co-PCL includes four diads: DTC-CL, CL-CL, DTC-DTC and CLDTC, which were determined by the specific signals in 1H-NMR spectra. Based on the typical signals of the formate (δ=8.08) and hydroxyl (δ = 3.34) end groups of PDTC-co-PCL, a mechanism involving DTC monomer inserts before CL during the initiation process was presumed. Furthermore, the thermal properties of amorphous copolymer were characterized by differential scanning calorimetry (DSC). The results support the random structure of PDTC-co-PCL.

  13. The mechanism of unexpected reduction of dimethyl pyridine-2,3-dicarboxylate to 1,2,3,4-tetrahydrofuro[3,4-b]-pyridin-5(7H)-one with sodium borohydride

    Institute of Scientific and Technical Information of China (English)

    Yan Bo Tang; Qing Jian Zhang; De Quan Yu

    2012-01-01

    An unexpected reduction of dimethyl pyridine-2,3-dicarboxylate to 1,2,3,4-tetrahydrofuro[3,4-b]pyridin-5(7H)-one with sodium borohydride in ethanol and tetrahydrofuran,respectively,is described,a hypothetic mechanism for the unusual reductive product is proposed.

  14. Synthesis, structure and gas-phase reactivity of the mixed silver hydride borohydride nanocluster [Ag3(μ3-H)(μ3-BH4)L(Ph)3]BF4 (L(Ph) = bis(diphenylphosphino)methane).

    Science.gov (United States)

    Zavras, Athanasios; Ariafard, Alireza; Khairallah, George N; White, Jonathan M; Mulder, Roger J; Canty, Allan J; O'Hair, Richard A J

    2015-11-21

    Borohydrides react with silver salts to give products that span multiple scales ranging from discrete mononuclear compounds through to silver nanoparticles and colloids. The cluster cations [Ag3(H)(BH4)L3](+) are observed upon electrospray ionization mass spectrometry of solutions containing sodium borohydride, silver(I) tetrafluoroborate and bis(dimethylphosphino)methane (L(Me)) or bis(diphenylphosphino)methane (L(Ph)). By adding NaBH4 to an acetonitrile solution of AgBF4 and L(Ph), cooled to ca. -10 °C, we have been able to isolate the first mixed silver hydride borohydride nanocluster, [Ag3(μ3-H)(μ3-BH4)L(Ph)3]BF4, and structurally characterise it via X-ray crystallography. Combined gas-phase experiments (L(Me) and L(Ph)) and DFT calculations (L(Me)) reveal how loss of a ligand from the cationic complexes [Ag3(H)(BH4)L3](+) provides a change in geometry that facilitates subsequent loss of BH3 to produce the dihydride clusters, [Ag3(H)2Ln](+) (n = 1 and 2). Together with the results of previous studies (Girod et al., Chem. - Eur. J., 2014, 20, 16626), this provides a direct link between mixed silver hydride/borohydride nanoclusters, silver hydride nanoclusters, and silver nanoclusters.

  15. Structural analysis of some bis-(8-isopropyl-isoquinolinium) derivatives reveals a preferential folded conformation leading to a stereoselective attack by sodium borohydride

    Science.gov (United States)

    Dilly, Sébastien; Badarau, Eduard; Dufour, Fabien; Nistor, Iolanda; Hubert, Philippe; Seutin, Vincent; Wouters, Johan; Liégeois, Jean-François

    2014-09-01

    Reduction of symmetrical bis-isoquinolinium derivatives with sodium borohydride generates normally a mixture of three 1,2,3,4-tetrahydroisoquinoline stereoisomers. In a series of 8-isopropyl analogues, chiral resolution failed for the analogues with propyl and m-xylyl linkers since two and one peaks respectively were detected by HPLC. Further analysis by MS and CD of both peaks of the propyl analogue revealed that each peak corresponds to an enantiomer. Conformational analysis and X-ray cristallography showed a folded conformation of the propyl and m-xylyl analogues responsible for the observed stereoselectivity following the reduction step. Additional 1H NMR investigations confirm structural features detected by theoretical analysis.

  16. Surface-enhanced Raman scattering study of riboflavin on borohydride-reduced silver colloids: Dependence of concentration, halide anions and pH values

    Science.gov (United States)

    Liu, Fangfang; Gu, Huaimin; Lin, Yue; Qi, Yajing; Dong, Xiao; Gao, Junxiang; Cai, Tiantian

    2012-01-01

    The influences of concentration, halide anions and pH on the surface-enhanced Raman scattering (SERS) of riboflavin adsorbed on borohydride-reduced silver colloids were studied. The optimum concentration for the SERS of riboflavin is 10 -6 mol/L while the SERS enhancement varies for different modes. The addition of 0.2 mol/L halide (NaCl, NaBr, and NaI) aqueous solutions, leads to a general decrease of the SERS intensity and a change of spectral profile of riboflavin excited at 514.5 nm. Riboflavin interacts with the silver surface possibly through the C dbnd O and N-H modes of the uracil ring. The SERS spectra of riboflavin were recorded in the 3.4-11.6 pH range. By analyzing several SERS marker bands, the protonated, deprotonated or the coexistence of both molecular species adsorbed on the colloidal silver particles was proved.

  17. Electrochemical Characteristics of LaNi4.5Al0.5 Alloy Used as Anodic Catalyst in a Direct Borohydride Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    Lianbang Wang; Guobin Wu; Zhenzhen Yang; Yunfang Gao; Xinbiao Mao; Chun'an Ma

    2011-01-01

    Fuel cells using borohydride as the fuel have received much attention because of high energy density and theoretical working potential. In this work, LaNi4.5Al0.5 hydrogen storage alloy used as the anodic material has been investigated. It was found that the increasing; operation temperature was helpful to the open-circuit potential, the discharge potential and the power density, but showed a negative effect on the utilization of the fuel due to the accelerated hydrogen evolution. The high KOH concentration was favorable for high-rate discharge capability. The adsorption and transformation of hydrogen on LaNi4.5Al0.5 alloy electrode has been observed, but its contribution to the discharge capability during a high-rate discharge was small.

  18. Research and development of foreign submarine sodium borohydride hydrolysis hydrogen generation%国外潜艇硼氢化钠水解制氢的研究与进展

    Institute of Scientific and Technical Information of China (English)

    李宏伟; 李大鹏; 张晓东

    2012-01-01

    叙述了国外潜艇AIP装置硼氢化钠水解制氢的研究与进展,介绍了硼氢化钠溶液水解制氢方法、水解反应催化剂,描述了潜艇硼氢化钠水解制氢系统、管式和一体式硼氢化钠水解制氢反应器的组成与工作,分析了制氢器反应区内的两相流动现象、反应区体积和换热-冷凝器传热面积要求,以及制氢器内液滴的分离、固体颗粒的沉淀和悬浮物的过滤、制氢器的动态特性等问题.%Research and development of foreign submarine AIP sodium borohydride hydrolysis hydrogen generation is stated in this paper. Method and catalyzer of sodium borohydride hydrolysis hydrogen generation are introduced. Submarine system of sodium borohydride hydrolysis hydrogen generation, constitution and working of tubular and integrative reactors of sodium borohydride hydrolysis hydrogen generation are described. Two-phase flow phenomena, requirements of reactor volume and heat-transfer surface of heat-exchanger-condenser, separation of liquid dribbles, precipitin of solid grains and filtration of suspending particles in the hydrogen generator, as well as dynamic characteristic of hydrogen generator are analyzed.

  19. Preparation and characterization of PtRu/C, PtBi/C, PtRuBi/C electrocatalysts for direct electro-oxidation of ethanol in PEM fuels cells using the method of reduction by sodium borohydride

    International Nuclear Information System (INIS)

    Pt/C, PtBi/C, PtRu/C and PtRuBi/C electrocatalysts were prepared by a borohydride reduction methodology and tested for ethanol oxidation. This methodology consists in mix a solution with sodium hydroxide and sodium borohydride to a mixture containing water/isopropyl alcohol, metallic precursors and the Vulcan XC 72 carbon support. It was studied the addition method of borohydride (drop by drop addition or rapid addition). The obtained electrocatalysts were characterized by energy dispersive X ray spectroscopy (EDX), thermogravimetric analysis (TGA), X ray diffraction (XRD), transmission electron microscope (TEM) and cyclic voltammetry. The ethanol electro-oxidation was studied by cyclic voltammetry and chronoamperometry using the thin porous coating technique. The electrocatalysts were tested in real conditions of operation by unit cell tests. The stability of PtRuBi/C electrocatalysts was evaluated by cyclic voltammetry, chronoamperometry using the ultra-thin porous coating technique and ring-disk electrode. The PtRuBi/C electro catalyst apparently presented a good performance for ethanol electro-oxidation but experimental evidences showed accentuated bismuth dissolution. (author)

  20. 活化硼氢化钠在有机合成中的应用%The Applications of the Activated Sodium Borohydride in Organic Synthesis

    Institute of Scientific and Technical Information of China (English)

    戴利

    2012-01-01

    介绍了有机合成反应中NaBH4与添加剂共同作用的反应,其中包括烯烃和炔烃的还原,羧酸的还原,氨基酸及其衍生物的还原,羧酸酯的还原,酰胺的还原,腈基的还原,酰氯的还原,硝基化合物的还原,醛酮的还原等。与LiAIH4的还原相比较,其反应条件更温和,反应过程更安全、易操控、易放大。%Introduced the applications of the activated sodium borohydride . It concluded reduction of alkene, alkyne, carboxylic acid, carboxylic acid ester, amide, nitrile group, acyl chloride, nitro group, aldehydes, ketones, amino acids as well as their derivatives. Comparing to the reduction of lithium aluminum hydride, it had milder reaction conditions, more secure reaction process and it was more easily controlled and amplified.

  1. Experimental study on the formation and growth of electroless nickel-boron coatings from borohydride-reduced bath on mild steel

    Energy Technology Data Exchange (ETDEWEB)

    Vitry, Veronique, E-mail: veronique.vitry@umons.ac.be [Service de Metallurgie, Universite de Mons, Rue de l' Epargne 56, 7000 Mons (Belgium); Sens, Adeline [Service de Metallurgie, Universite de Mons, Rue de l' Epargne 56, 7000 Mons (Belgium); Kanta, Abdoul-Fatah [Service de Sciences des Materiaux, Universite de Mons, Rue de l' Epargne 56, 7000 Mons (Belgium); Delaunois, Fabienne [Service de Metallurgie, Universite de Mons, Rue de l' Epargne 56, 7000 Mons (Belgium)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Initiation mechanism of electroless Ni-B on St-37 steel has been identified. Black-Right-Pointing-Pointer Different phases of the plating process were observed and identified. Black-Right-Pointing-Pointer Influence of chemical heterogeneity on coating morphology was revealed. Black-Right-Pointing-Pointer Batch replenishment of the plating bath induces new germination phase. - Abstract: Quality and homogeneity of electroless nickel-boron coatings are very important for applications in corrosion and electronics and are completely dependent on the formation of the deposit. The growth and formation process of electroless nickel-boron was investigated by immersing mild steel (St-37) samples in an un-replenished bath for various periods of time (from 5 s to 1 h). The coatings obtained at the different stages of the process were then characterized: thickness was measured by SEM, morphology was observed, weight gain was recorded and top composition of the coatings was obtained from XPS. Three main phases were identified during the coating formation and links between plating time, instantaneous deposition rate, chemistry of last formed deposit and morphology were established. The mechanism for initial deposition on steel substrate for borohydride-reduced electroless nickel bath was also observed. Those results were confronted with chemistry evolution in the unreplenished plating bath during the process. This allowed getting insight about phenomena occurring in the plating bath and their influence on coating formation.

  2. Sodium Borohydride Reduction of Aqueous Silver-Iron-Nickel Solutions: a Chemical Route to Synthesis of Low Thermal Expansion-High Conductivity Ag-Invar Alloys

    Science.gov (United States)

    Sterling, E. A.; Stolk, J.; Hafford, L.; Gross, M.

    2009-07-01

    Thermal management is a critical concern in the design and performance of electronics systems. If heat extraction and thermal expansion are not properly addressed, the thermal mismatch among dissimilar materials may give rise to high thermal stresses or interfacial shear strains, and ultimately to premature system failure. In this article, we present a chemical synthesis process that yields Ag-Invar (64Fe-36Ni) alloys with a range of attractive properties for thermal management applications. Sodium borohydride reduction of an aqueous Ag-Fe-Ni metal salt solution produces nanocrystalline powders, and conventional powder processing converts this powder to fine-grained alloys. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy, thermomechanical analysis, and electrical conductivity measurements; thermal conductivity is estimated using the Wiedemann-Franz law. Sintering of Ag-Fe-Ni powders leads to the formation of two-phase silver-Invar alloys with low coefficients of thermal expansion (CTEs) and relatively high electrical conductivities. A sample of 50Ag-50Invar exhibits a CTE of 8.76 μm/(m· °C) and an estimated thermal conductivity of 236 W/(m·K). The Ag-Invar alloys offer thermodynamic stability and tailorable properties, and they may help address the need for improved packaging materials.

  3. HYDROGEN GENERATION FROM SOLID SODIUM BOROHYDRIDE WITH FERRIC CATALYTS%基于铁盐催化的固态硼氢化钠制氢研究

    Institute of Scientific and Technical Information of China (English)

    方朝君; 闫常峰; 郭常青

    2012-01-01

    Sodium borohydride' s properties such as environmental friendly, reliability, efficiency etc. , make it a good source of hydrogen. Its hydrolysis reaction with the assistance of catalysts to liberate hydrogen gas is easily controllable. Tests were conducted to evaluate effects of ferric sulfate concentration, initial reaction temperature and solution feeding flow rate on hydrogen generation using non-noble ferric sulfate as catalyst. Ferric sulfate' s catalytic activity is evidently higher than ferric nitrate and ferric chloride. Maximum H2 flow was obtained under the condition of ferric sulfate in 1. 5mol/L. The conversion increases slowly with the increasing of reaction temperature in the range of 20-48℃. And the conversion could finally reach over 90% .%以非贵金属铁盐为催化剂,考察不同浓度的Fe2(SO4)3溶液、初始反应温度和不同进液速率下的固态NaBH4水解产氢性能.实验表明:相同浓度下,Fe2(SO4)3的催化产氢性能高于Fe(NO3)2和FeCl3.在Fe2(SO4)3溶液浓度为1.5mol/L时产氢速率出现最大值,提高Fe2(SO4)3浓度,可提高平均产氢速率;在20 ~48℃范围内,随反应温度的升高,产氢转化率略有上升,最终均能达到90%以上.

  4. XPS, TEM and SAD investigations of nanosized Co{sub x}B{sub y}H{sub z} particles obtained by two different borohydride methods

    Energy Technology Data Exchange (ETDEWEB)

    Krastev, V. [Bulgarian Acad. of Sci., Sofia (Bulgaria). Inst. of General and Inorg. Chem.; Stoycheva, M. [Central Laboratory of Electrochemical Power Sources, Bulgarian Academy of Sciences, Sofia 1113 (Bulgaria); Lefterova, E. [Central Laboratory of Electrochemical Power Sources, Bulgarian Academy of Sciences, Sofia 1113 (Bulgaria); Dragieva, I. [Central Laboratory of Electrochemical Power Sources, Bulgarian Academy of Sciences, Sofia 1113 (Bulgaria); Stoynov, Z. [Central Laboratory of Electrochemical Power Sources, Bulgarian Academy of Sciences, Sofia 1113 (Bulgaria)

    1996-07-01

    The nanosized Co{sub x}B{sub y}H{sub z} particles synthesised by the ``tea`` and ``antigravity`` methods using a borohydride reduction process have been subjected to structure and composition studies by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and selected area diffraction (SAD). The amounts of the elements Co, B, O{sub 2}, H{sub 2} and C as mean volume values, and surface values for the as-prepared particles, as well as after Ar{sup +} etching to a depth of about 15 nm and 30 nm from the initial particle surface, are determined. About 1.5 atoms of cobalt per atom of boron correspond to samples obtained by the ``antigravity`` method. The binding energy (BE) of 1s electrons of boron atoms has only one value. These particles are angular and are in the typical nanocrystalline state. In the case of samples prepared by the ``tea`` method, two atoms of cobalt per atom of boron are found. The presence of two kinds of BE (B{sup I} and B{sup II}) of 1s electrons of boron atoms in the particles obtained by the ``tea`` method is observed and almost equal amounts of these two states are established in the spectrum. The particles` shape and structure are typical of the amorphous state. The fact that there is one peak when the ``antigravity`` method is applied, in contrast to the two peaks with the ``tea`` method indicates the presence of a metal amorphous state in the latter case. (orig.)

  5. NaBH4 (sodium borohydride) hydrogen generator with a volume-exchange fuel tank for small unmanned aerial vehicles powered by a PEM (proton exchange membrane) fuel cell

    International Nuclear Information System (INIS)

    A proton exchange membrane fuel cell system integrated with a NaBH4 (sodium borohydride) hydrogen generator was developed for small UAVs (unmanned aerial vehicles). The hydrogen generator was composed of a catalytic reactor, liquid pump and volume-exchange fuel tank, where the fuel and spent fuel exchange the volume within a single fuel tank. Co–B catalyst supported on a porous ceramic material was used to generate hydrogen from the NaBH4 solution. Considering the power consumption according to the mission profile of a UAV, the power output of the fuel cell and auxiliary battery was distributed passively as an electrical load. A blended wing-body was selected considering the fuel efficiency and carrying capability of fuel cell components. First, the fuel cell stack and hydrogen generator were evaluated under the operating conditions, and integrated into the airframe. The ground test of the complete fuel cell UAV was performed under a range of load conditions. Finally, the fuel cell powered flight test was made for 1 h. The volume-exchange fuel tank minimized the fuel sloshing and the change in center of gravity due to fuel consumption during the flight, so that much stable operation of the fuel cell system was validated at different flight modes. - Highlights: • PEMFC system with a NaBH4 hydrogen source was developed for small UAVs. • Volume-exchange fuel tank was used to reduce the size of the fuel cell system. • Passive power management was used for a stable power output during the flight. • BWB UAV was selected by taking the fuel cell integration into consideration. • Stable operation of the fuel cell system was verified from the flight test

  6. Immobilization of CoCl2 (cobalt chloride) on PAN (polyacrylonitrile) composite nanofiber mesh filled with carbon nanotubes for hydrogen production from hydrolysis of NaBH4 (sodium borohydride)

    International Nuclear Information System (INIS)

    Composite nanofiber sheets containing multiwalled carbon nanotubes and cobalt chloride dispersed in PAN (polyacrylonitrile) were produced by an electrospinning technique. The synthesized PAN/CoCl2/CNTs composite nanofiber was used as the catalyst for hydrogen production from the hydrolysis of sodium borohydride. FT-IR characterization showed that the pretreated CNTs possess different organic functional groups which help improve the compatibility between CNTs and PAN organic polymer. SEM (scanning electron microscopy), TEM (transmission electron microscopy) and EDX (energy-dispersive X-ray technique) were used to characterize the composite nanofiber and it was found that CNTs can be coaxially dispersed into the PAN nanofiber. During the hydrolysis of NaBH4, this PAN/CoCl2/CNTs composite nanofiber exhibited higher catalytic activity compared to the composite without CNTs doping. Kinetic analysis of NaBH4 hydrolysis shows that the reaction of NaBH4 hydrolysis based on this catalyst can be ascribed to the first-order reaction and the activation energy of the catalyst was approximately 52.857 kJ/mol. Meanwhile, the composite nanofiber catalyst shows excellent stability and reusability in the recycling experiment. - Highlights: • Composite nanofiber sheets were prepared via electrospinning. • PAN (polyacrylonitrile)/CoCl2 (cobalt chloride)/CNTs (carbon nanotubes) nanofiber was used as the catalyst for hydrogen production. • CNTs can be coaxially dispersed into the PAN nanofiber. • PAN/CoCl2/CNTs composite nanofiber exhibited higher catalytic activity. • The composite nanofiber catalyst shows excellent stability and reusability

  7. 硼氢化钠制氢技术在质子交换膜燃料电池中的研究进展%Recent advances in the study of sodium borohydride hydrolysis for pure hydrogen supply to PEM fuel cell

    Institute of Scientific and Technical Information of China (English)

    王玉晓

    2009-01-01

    硼氢化钠储氢量高达10.6%,安全、无爆炸危险,携带和运输方便;供氢系统设备简单,启动速度快,产氢速度可调,因此是一个非常良好的氢载体,是为质子交换膜燃料电池供氢的理想储氢介质.硼氢化钠供氢系统也已逐步应用于质子交换膜燃料电池电源中.介绍了这种制氢方式的几项关键技术:硼氢化钠水解制氢催化剂、硼氢化钠制氢反应器、氢气净化系统等在质子交换膜燃料电池中的研究进展,并指出了今后的研究发展方向.%Sodium borohydride contains hydrogen as high as 10.6%, and it is safe, no fire and explosion danger, and portable. This hydrogen supply system has the features of simple structure, fast starting, and adjustable hydrogen production speed. Therefore, sodium borohydride is a very promising hydrogen carrier and a perfect medium for pure hydrogen supply to proton exchange membrane fuel cell (PEMFC). In fact, the hydrolysis of sodium borohydride for hydrogen supply to PEMFC is in the way to real application. This review summarizes the recent advances in this hydrogen generation system including catalysts, reactors and purification methods, and the direction for sequent research is also discussed.

  8. Preparation and characterization of PtRu/C, PtBi/C, PtRuBi/C electrocatalysts for direct electro-oxidation of ethanol in PEM fuels cells using the method of reduction by sodium borohydride; Preparacao e caracterizacao de eletrocatalisadores PtRu/C, PtBi/C, PtRuBi/C para eletro-oxidacao direta de etanol em celulas a combustivel tipo PEM utilizando a metodologia da reducao via borohidreto de sodio

    Energy Technology Data Exchange (ETDEWEB)

    Brandalise, Michele

    2010-07-01

    Pt/C, PtBi/C, PtRu/C and PtRuBi/C electrocatalysts were prepared by a borohydride reduction methodology and tested for ethanol oxidation. This methodology consists in mix a solution with sodium hydroxide and sodium borohydride to a mixture containing water/isopropyl alcohol, metallic precursors and the Vulcan XC 72 carbon support. It was studied the addition method of borohydride (drop by drop addition or rapid addition). The obtained electrocatalysts were characterized by energy dispersive X ray spectroscopy (EDX), thermogravimetric analysis (TGA), X ray diffraction (XRD), transmission electron microscope (TEM) and cyclic voltammetry. The ethanol electro-oxidation was studied by cyclic voltammetry and chronoamperometry using the thin porous coating technique. The electrocatalysts were tested in real conditions of operation by unit cell tests. The stability of PtRuBi/C electrocatalysts was evaluated by cyclic voltammetry, chronoamperometry using the ultra-thin porous coating technique and ring-disk electrode. The PtRuBi/C electro catalyst apparently presented a good performance for ethanol electro-oxidation but experimental evidences showed accentuated bismuth dissolution. (author)

  9. Nanoconfined Alkali-metal borohydrides for Reversible Hydrogen Storage

    NARCIS (Netherlands)

    Ngene, P.

    2012-01-01

    Hydrogen has been identified as a promising energy carrier. Its combustion is not associated with pollution when generated from renewable energy sources like solar and wind. The large-scale use of hydrogen for intermittent energy storage and as a fuel for cars can contribute to the realization of a

  10. Structural phase transitions and adduct release in calcium borohydride

    Energy Technology Data Exchange (ETDEWEB)

    Paolone, A.; Palumbo, O.; Rispoli, P.; Miriametro, A.; Cantelli, R.; Luedtke, A.; Rönnebro, E.; Chandra, D.

    2011-09-01

    Ca(BH4)2 compounds were investigated above room temperature by anelastic spectroscopy (AS) and concomitant measurements of thermogravimetry and mass spectrometry (TGA/MS). Both AS and TGA/MS indicate that even after a thermal treatment at 125 °C for 20 h, a non-negligible residual of THF adduct is still present in the sample, which can be removed on a subsequent thermal treatment at temperatures lower than 250 °C. Above 250 °C dehydrogenation takes place. Moreover, AS sensitively detects the occurrence of the α → α’ structural phase transition around 180 °C, and the α’ → β transformation, which is completed around 330 °C. Finally, we also show that both transitions are irreversible and are not accompanied by a latent heat.

  11. Destabilized and catalyzed borohydride for reversible hydrogen storage

    Science.gov (United States)

    Mohtadi, Rana F.; Nakamura, Kenji; Au, Ming; Zidan, Ragaiy

    2012-01-31

    A process of forming a hydrogen storage material, including the steps of: providing a first material of the formula M(BH.sub.4).sub.X, where M is an alkali metal or an alkali earth metal, providing a second material selected from M(AlH.sub.4).sub.x, a mixture of M(AlH.sub.4).sub.x and MCl.sub.x, a mixture of MCl.sub.x and Al, a mixture of MCl.sub.x and AlH.sub.3, a mixture of MH.sub.x and Al, Al, and AlH.sub.3. The first and second materials are combined at an elevated temperature and at an elevated hydrogen pressure for a time period forming a third material having a lower hydrogen release temperature than the first material and a higher hydrogen gravimetric density than the second material.

  12. First-principles determination of the structure of magnesium borohydride.

    Science.gov (United States)

    Zhou, Xiang-Feng; Oganov, Artem R; Qian, Guang-Rui; Zhu, Qiang

    2012-12-14

    The energy landscape of Mg(BH(4))(2) under pressure is explored by ab initio evolutionary calculations. Two new tetragonal structures, with space groups P4 and I4(1)/acd, are predicted to be lower in enthalpy by 15.4 and 21.2 kJ/mol, respectively, than the earlier proposed P4(2)nm phase. We have simulated x-ray diffraction spectra, lattice dynamics, and equations of state of these phases. The density, volume contraction, bulk modulus, and simulated x-ray diffraction patterns of I4(1)/acd and P4 structures are in excellent agreement with the experimental results.

  13. Borohydride electro-oxidation in a molten alkali hydroxide eutectic mixture and a novel borohydride-periodate battery

    Science.gov (United States)

    Wang, Andrew; Gyenge, Előd L.

    2015-05-01

    The electrochemical oxidation of BH4- in a molten NaOH-KOH eutectic mixture (0.515:0.485 mole fractions), is investigated for the first time by cyclic voltammetry and electrochemical impedance spectroscopy. Anodically oxidized Ni is electrocatalytically more active than Pt for BH4- oxidation in the molten alkali electrolyte as shown by the more than three times higher exchange current density (i.e. 15.8 mA cm-2 vs. 4.6 mA cm-2 at 185 °C). Next the proof-of-concept for a novel BH4-/IO4- molten alkali electrolyte battery is presented. Using oxidized Ni mesh anode and Pt mesh cathode a maximum power density of 63 mW cm-2 is achieved at 185 °C.

  14. Crystal Structure of a Lightweight Borohydride from Submicrometer Crystallites by Precession Electron Diffraction

    OpenAIRE

    Hadermann, Joke; Abakumov, Artem; Rompaey, van, R.S.A.R.; Perkisas, Tyche; Filinchuk, Yaroslav; Tendeloo, van, G.

    2012-01-01

    Abstract: We demonstrate that precession electron diffraction at low-dose conditions can be successfully applied for structure analysis of extremely electron-beam-sensitive materials. Using LiBH4 as a test material, complete structural information, including the location of the H atoms, was obtained from submicrometer-sized crystallites. This demonstrates for the first time that, where conventional transmission electron microscopy techniques fail, quantitative precession electron diffraction ...

  15. Synthesis of rock-salt type lithium borohydride and its peculiar Li+ ion conduction properties

    Directory of Open Access Journals (Sweden)

    R. Miyazaki

    2014-05-01

    Full Text Available The high energy density and excellent cycle performance of lithium ion batteries makes them superior to all other secondary batteries and explains why they are widely used in portable devices. However, because organic liquid electrolytes have a higher operating voltage than aqueous solution, they are used in lithium ion batteries. This comes with the risk of fire due to their flammability. Solid electrolytes are being investigated to find an alternative to organic liquid. However, the nature of the solid-solid point contact at the interface between the electrolyte and electrode or between the electrolyte grains is such that high power density has proven difficult to attain. We develop a new method for the fabrication of a solid electrolyte using LiBH4, known for its super Li+ ion conduction without any grain boundary contribution. The modifications to the conduction pathway achieved by stabilizing the high pressure form of this material provided a new structure with some LiBH4, more suitable to the high rate condition. We synthesized the H.P. form of LiBH4 under ambient pressure by doping LiBH4 with the KI lattice by sintering. The formation of a KI - LiBH4 solid solution was confirmed both macroscopically and microscopically. The obtained sample was shown to be a pure Li+ conductor despite its small Li+ content. This conduction mechanism, where the light doping cation played a major role in ion conduction, was termed the “Parasitic Conduction Mechanism.” This mechanism made it possible to synthesize a new ion conductor and is expected to have enormous potential in the search for new battery materials.

  16. Dehydrogenation in lithium borohydride/conventional metal hydride composite based on a mutual catalysis

    DEFF Research Database (Denmark)

    Yu, X.B.; Shi, Qing; Vegge, Tejs;

    2009-01-01

    The dehydrogenation of LiBH4 ball-milled with hydrogenated 40Ti–15Mn–15Cr–30V alloy was investigated. It was found that there is a mutual catalysis between the two hydrides, lowering the temperature of hydrogen release from both hydrides. In the case of 1h milled LiBH4/40Ti–15Mn–15Cr–30V with a...

  17. Recent Advances in the Use of Sodium Borohydride as a Solid State Hydrogen Store

    Directory of Open Access Journals (Sweden)

    Jianfeng Mao

    2015-01-01

    Full Text Available The development of new practical hydrogen storage materials with high volumetric and gravimetric hydrogen densities is necessary to implement fuel cell technology for both mobile and stationary applications. NaBH4, owing to its low cost and high hydrogen density (10.6 wt%, has received extensive attention as a promising hydrogen storage medium. However, its practical use is hampered by its high thermodynamic stability and slow hydrogen exchange kinetics. Recent developments have been made in promoting H2 release and tuning the thermodynamics of the thermal decomposition of solid NaBH4. These conceptual advances offer a positive outlook for using NaBH4-based materials as viable hydrogen storage carriers for mobile applications. This review summarizes contemporary progress in this field with a focus on the fundamental dehydrogenation and rehydrogenation pathways and properties and on material design strategies towards improved kinetics and thermodynamics such as catalytic doping, nano-engineering, additive destabilization and chemical modification.

  18. High volumetric hydrogen density phases of magnesium borohydride at high-pressure: A first-principles study

    Institute of Scientific and Technical Information of China (English)

    Fan Jing; Bao Kuo; Duan De-Fang; Wang Lian-Cheng; Liu Bing-Bing; Cui Tian

    2012-01-01

    The previously proposed theoretical and experimental structures,bond characterization,and compressibility of Mg(BH4)2 in a pressure range from 0 to 10 GPa are studied by ab initio density-functional calculations.It is found that the ambient pressure phases of meta-stable I41/amd and unstable P-3ml proposed recently are extra stable and cannot decompose under high pressure.Enthalpy calculation indicates that the ground state of F222 structure proposed by Zhou et al.[2009 Phys.Rev.B 79 212102]will transfer to I41/amd at 0.7 GPa,and then to a P-3m1 structure at 6.3 GPa.The experimental P6122 structure (α-phase) transfers to I41/amd at 1.2 GPa.Furthermore,both I41/amd and P-3m1 can exist as high volumetric hydrogen density phases at low pressure.Their theoretical volumetric hydrogen densities reach 146.351 g H2/L and 134.028 g H2/L at ambient pressure,respectively.The calculated phonon dispersion curve shows that the I41/amd phase is dynamically stable in a pressure range from 0 to 4 GPa and the P-3ml phase is stable at pressures higher than 1 GPa.So the I41/amd phase may be synthesized under high pressure and retained to ambient pressure.Energy band structures show that they are both always ionic crystalline and insulating with a band-gap of about 5 eV in this pressure range.In addition,they each have an anisotropic compressibility.The c axis of these structures is easy to compress.Especially,the c axis and volume of P-3m1 phase are extraordinarily compressible,showing that compression along the c axis can increase the volumetric hydrogen content for both I41/amd and P-3m1 structures.

  19. Quasielastic neutron scattering study of tetrahydroborate anion dynamical perturbations in sodium borohydride due to partial halide anion substitution

    Energy Technology Data Exchange (ETDEWEB)

    Verdal, Nina [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102 (United States); Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742-2115 (United States); Udovic, Terrence J. [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102 (United States); Rush, John J. [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102 (United States); Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742-2115 (United States); Skripov, Alexander V. [Institute of Metal Physics, Ural Branch of the Russian Academy of Sciences, Ekaterinburg 620990 (Russian Federation)

    2015-10-05

    Highlights: • NaBH{sub 4}–NaX (X = Cl, I) solutions were made by ball-milling/annealing pure compounds. • BH{sub 4}{sup −} reorientational motions were studied by quasielastic neutron scattering. • Mobility increased from X = Cl to NaBH{sub 4} to X = I, consistent with expanding lattices. • Near 400 K, BH{sub 4}{sup −} favored cubic tumbling for X = Cl and tetrahedral tumbling for X = I. • Activation energies were in the range of 11–12 kJ mol{sup −1} for both compounds. - Abstract: Equimolar NaBH{sub 4}–NaX (X = Cl and I) solid solutions were synthesized to study, via quasielastic neutron scattering, the effect of partial halide anion substitution on the reorientational dynamics of tetrahydroborate (BH{sub 4}{sup −}) anions in NaBH{sub 4}. The BH{sub 4}{sup −} reorientational mobility increased in the order of NaBH{sub 4}–NaCl, NaBH{sub 4}, and NaBH{sub 4}–NaI, which corresponded with expanding face-centered-cubic lattices accommodating the respective increasing sizes of the Cl{sup −}, BH{sub 4}{sup −}, and I{sup −} anions. The BH{sub 4}{sup −} anions in NaBH{sub 4}–NaCl were found (at least above 400 K) to undergo ‘cubic’ tumbling motions with the four H atoms per anion visiting all eight corners of a cube, similar to what was previously observed for NaBH{sub 4}. In contrast, the BH{sub 4}{sup −} anions in NaBH{sub 4}–NaI were found to undergo something more akin to ‘tetrahedral’ tumbling motions, where the H atoms visit all four corners of a tetrahedron. Despite a noticeable softening of the BH{sub 4}{sup −} torsional energies with increasing lattice constant amongst NaBH{sub 4} and the two solid solutions, all three compounds exhibited similar activation energies for reorientation of about 11–12 kJ mol{sup −1}.

  20. Cobalt,a reactive metal in releasing hydrogen from sodium borohydride by hydrolysis:A short review and a research perspective

    Institute of Scientific and Technical Information of China (English)

    DEMIRCI; Umit; B; AKDIM; Ouardia; HANNAUER; Julien; CHAMOUN; Rita; MIELE; Philippe

    2010-01-01

    Cobalt is commonly admitted as being a promising catalyst in accelerating NaBH4 hydrolysis,being as reactive as noble metals and much more cost-effective.This is the topic of the present paper.Herein,we survey(i) the NaBH4-devoted literature while especially focusing on the Co catalysts and(ii) our work on the same topic.Finally,we report(iii) reactivity results of newly developed Co-based catalysts.From both surveys,it mainly stands out that Co has been investigated as catalysts in various forms:namely,as chlorides,reduced nanoparticles(metal Co,Co boride,Co-B alloy),supported over supports and shaped.In doing so the reactivity can be easily varied achieving H2 generation rates from few to >1000 L(H2)/min·g(metal).Nevertheless,our work can be distinguished from the NaBH4 literature.Indeed,we are working on strategies that focus on making alternative Co-based catalysts.One of these strategies is illustrated here as we report new reactivity data of Co-based bimetallic supported catalysts.For example,we show that 20 wt% Co90Y10/γAl2O3-20 wt% Co95Hf5/γAl2O3 > 20 wt% Co99Zr1/γAl2O3 > 20 wt% Co/γAl2O3,the best catalysts showing HGRs of about 245 mL(H2)/min or 123 L(H2) /min·g(metals).

  1. Theoretical and experimental study on Mg(BH{sub 4}){sub 2}–Zn(BH{sub 4}){sub 2} mixed borohydrides

    Energy Technology Data Exchange (ETDEWEB)

    Albanese, E. [Dipartimento di Chimica and NIS, Università di Torino, Via P. Giuria 7-9, I-10125 Torino (Italy); Kalantzopoulos, G.N. [Institute for Energy Technology, Department of Physics, P.O. Box 40, NO-2027 Kjeller (Norway); Vitillo, J.G.; Pinatel, E.; Civalleri, B. [Dipartimento di Chimica and NIS, Università di Torino, Via P. Giuria 7-9, I-10125 Torino (Italy); Deledda, S. [Institute for Energy Technology, Department of Physics, P.O. Box 40, NO-2027 Kjeller (Norway); Bordiga, S. [Dipartimento di Chimica and NIS, Università di Torino, Via P. Giuria 7-9, I-10125 Torino (Italy); Hauback, B.C. [Institute for Energy Technology, Department of Physics, P.O. Box 40, NO-2027 Kjeller (Norway); Baricco, M., E-mail: marcello.baricco@unito.it [Dipartimento di Chimica and NIS, Università di Torino, Via P. Giuria 7-9, I-10125 Torino (Italy)

    2013-12-15

    Highlights: •An ideal mixing behavior was predicted for Mg{sub (1−x)}Zn{sub x}(BH{sub 4}){sub 2} solid solutions. •A value of 30kJmol{sub H2}{sup -1} for the enthalpy of decomposition has been calculated for x = 0.2. •Samples have been synthesized ball milling Mg(BH{sub 4}){sub 2} and ZnCl{sub 2} in a molar ratio 1:0.7. •B{sub 2}H{sub 6} is released preventing the reversibility of hydrogen sorption. •Thermodynamic calculations supported experimental data. -- Abstract: After a screening of possible systems prone to give an enthalpy of decomposition close to 30kJmol{sub H2}{sup -1}, i.e. suitable for a dehydrogenation process close to room temperature and pressure, the Zn dissolution into Mg(BH{sub 4}){sub 2} has been investigated. The total energy of pure compounds and solid solutions has been computed by DFT calculations using the CRYSTAL09 code. To generate the Mg{sub (1−x)}Zn{sub x}(BH{sub 4}){sub 2} solid solution, α-phase of Mg(BH{sub 4}){sub 2} (space group P6{sub 1}22) has been considered, with a replacement of Mg{sup 2+} with Zn{sup 2+} ions, without lowering the symmetry of the crystalline structure. On the basis of DFT results, the enthalpy of decomposition has been estimated, considering MgH{sub 2}, Zn, α-B and H{sub 2} as products, and a value of 30kJmol{sub H2}{sup -1} has been calculated for x = 0.2. In order to verify the results of calculations, mixtures of Mg(BH{sub 4}){sub 2} and ZnCl{sub 2} with 1.0:0.7 ratio have been ball milled, both at room temperature and in cryo-conditions. Samples have been analyzed with a combination of experimental techniques (XRD, DSC, IR–ATR, TGA, TPD, PCI). The phase mixture obtained after the synthesis strongly depends on the milling conditions. For prolonged times, the formation of Zn and MgCl{sub 2} has been observed, suggesting the delivering of B-containing species during the milling. After heating, a hydrogen release, coupled with diborane delivering, has been observed for temperatures close to 100 °C, suggesting a significant decrease of the decomposition temperature with respect to pure Mg(BH{sub 4}){sub 2}. Theoretical and experimental results have been discussed on the basis of the possible reaction paths, as estimated from available thermodynamic databases.

  2. Halide Free M(BH4)2 (M = Sr, Ba, and Eu) Synthesis, Structure, and Decomposition.

    Science.gov (United States)

    Sharma, Manish; Didelot, Emilie; Spyratou, Alexandra; Lawson Daku, Latévi Max; Černý, Radovan; Hagemann, Hans

    2016-07-18

    Borohydrides have attained high interest in the past few years due to their high volumetric and gravimetric hydrogen content. Synthesis of di/trimetallic borohydride is a way to alter the thermodynamics of hydrogen release from borohydrides. Previously reported preparations of M(BH4)2 involved chloride containing species such as SrCl2. The presence of residual chloride (or other halide) ions in borohydrides may change their thermodynamic behavior and their decomposition pathway. Pure monometallic borohydrides are needed to study decomposition products without interference from halide impurities. They can also be used as precursors for synthesizing di/trimetallic borohydrides. In this paper we present a way to synthesize halide free alkaline earth metal (Sr, Ba) and europium borohydrides starting with the respective hydrides as precursors. Two novel high temperature polymorphs of Sr and Eu borohydrides and four polymorphs of Ba borohydride have been characterized by synchrotron X-ray powder diffraction, thermal analysis, and Raman and infrared spectroscopy and supported by periodic DFT calculations. The decomposition routes of these borohydrides have also been investigated. In the case of the decomposition of strontium and europium borohydrides, the metal borohydride hydride (M(BH4)H3, M = Sr, Eu) is observed and characterized. Periodic DFT calculations performed on room temperature Ba(BH4)2 revealed the presence of bidentate and tridentate borohydrides. PMID:27351948

  3. Effect of Reduction by Sodium Borohydride on the Structural Characteristics of Brown-Rotted Lignin%硼氢化钠还原对褐腐木质素结构特征的影响

    Institute of Scientific and Technical Information of China (English)

    李改云; 孙其宁; 秦特夫; 黄洛华

    2010-01-01

    采用FTLR、UV-Visible、NMR和GPC分析手段研究了褐腐木质素被.NaBH4还原前后的化学结构变化.FTIR表明褐腐木质素还原后1677 cm-1处与苯环共轭的羰基峰消失,1715 cm-1处非共轭羰基峰强度减弱,1509和1603 cm-1处苯环骨架振动吸收峰强度变化很小;UV表明褐腐木质素还原后位于288 nm的最强吸收峰和300~400nm区域的吸收强度降低;1H NMR表明褐腐木质素还原后甲氧基和酚羟基数量减少,醇羟基数量增加,褐腐木质素芳香环和结构单元联接键上的氢质子数增加;GPC表明褐腐木质素还原后分子量分布向高分子区域扩展,数均和重均分子量增大,分子量分布明显变宽.NaBH4在碱性环境中可以将褐腐木质素中的共轭羰基完全还原为羟基,非共轭羰基部分还原为羟基,其侧链结构部分被改变,苯环结构稳定,褐腐木质素在还原过程中发生了缩合反应.

  4. Development of binary anodic catalysts for direct oxidation of borohydride%硼氢化物直接氧化的二元催化剂研究进展

    Institute of Scientific and Technical Information of China (English)

    余丹梅; 申燕; 李小艳; 张代雄; 王洁

    2011-01-01

    直接硼氢燃料电池(DBFC)是一种以NaBH4/KBH4碱性溶液为阳极燃料的新型燃料电池.催化剂的种类严重影响着硼氢化物的直接氧化.综述了近年来直接硼氢燃料电池(DBFC)阳极用NiPt、Ni-Pd、Ag-Ni、Au-Co、Au-Pt等二元催化剂的研究现状.

  5. The use of superporous p(AAc (acrylic acid)) cryogels as support for Co and Ni nanoparticle preparation and as reactor in H2 production from sodium borohydride hydrolysis

    International Nuclear Information System (INIS)

    Here, we report for the first time the use of p(AAc (p(acrylic acid)) cryogel for in situ metal nanoparticle preparation, and their use as a superporous reactor for H2 generation from hydrolysis of NaBH4. Superporous p(AAc) cryogels and conventional hydrogels were prepared via free radical polymerization technique at low (−18 °C) and moderate (40 °C) temperatures, respectively. They were characterized by employing various methods such as swelling experiments, optical imaging, and SEM (Scanning Electron Microscopy) analysis. By reducing Co2+ and Ni2+ ions within p(AAc) cryogel and hydrogel matrices, the obtained Co and Ni metal nanoparticles were employed for H2 generation from NaBH4 hydrolysis. Various factors such as porosity, metal type, temperature, and the amount of sodium hydroxide were investigated to determine their effects on hydrogen generation from NaBH4 hydrolysis. Activation energy (Ea), enthalpy (ΔH#) and entropy (ΔS#) for NaBH4 hydrolysis by superporous p(AAc)-Co metal composites were 29.35 kJ mol−1,=36.85 kJ mol−1, and –157.88 J mol−1K−1, respectively. Cryogels showed better catalytic activity than conventional hydrogels in the hydrolysis reaction, and have a higher TOF (turnover frequency) value of 4.10 mol H2 (mol catalyst min)−1 compared to conventional hydrogels, due to its highly porous nature, short diffusion distances and fast response times. - Highlights: • Superporous cryogel supports for in situ metal nanoparticle preparation. • Fast H2 production from chemical hydride hydrolysis by cryogel-M composites. • Soft, superporous cryogel reactors for energy applications

  6. Process for synthesis of ammonia borane for bulk hydrogen storage

    Science.gov (United States)

    Autrey, S Thomas [West Richland, WA; Heldebrant, David J [Richland, WA; Linehan, John C [Richland, WA; Karkamkar, Abhijeet J [Richland, WA; Zheng, Feng [Richland, WA

    2011-03-01

    The present invention discloses new methods for synthesizing ammonia borane (NH.sub.3BH.sub.3, or AB). Ammonium borohydride (NH.sub.4BH.sub.4) is formed from the reaction of borohydride salts and ammonium salts in liquid ammonia. Ammonium borohydride is decomposed in an ether-based solvent that yields AB at a near quantitative yield. The AB product shows promise as a chemical hydrogen storage material for fuel cell powered applications.

  7. A novel synthesis of ethanolamine-2-14C

    International Nuclear Information System (INIS)

    Ethanolamine-2-14C was prepared by the reduction of benzyloxycarbonyl-glycine-1-14C methyl ester. The reduction was carried out with calcium borohydride and the protecting group was removed by hydrogenolysis. (author)

  8. Ambient Ionic Liquids Used in the Reduction ofAldehydes and Ketones

    Institute of Scientific and Technical Information of China (English)

    Dan Qian XU; Shu Ping LUO; Bao You LIU; Zhen Yuan XU; Yin Chu SHEN

    2004-01-01

    The sodium borohydride reduction of aldehydes and ketones to corresponding alcohols has been accomplished via the use of ionic liquids. The alcohols are easily obtained with excellent yields and the ionic liquid BMImBF4 could be reused.

  9. Effect of certain structural features of coal on Its tendency towards reduction

    Energy Technology Data Exchange (ETDEWEB)

    Grigor' yeva, Ye. A.; Bakirova, Ye.V.; Dzhalyabova, L.V.; Larina, N.K.; Lesnikova, Ye.B.; Zharova, M.N.,

    1981-01-01

    A study is made of the effect of easily destroyed ether groupings and organic-mineral bonds in coal structure on the tendency towards reduction with the help of hydrolytic destruction of coals and subsequent selective reduction by sodium borohydride.

  10. Innovative Materials and Systems for Solid State Hydrogen Storage

    OpenAIRE

    Capurso, Giovanni

    2013-01-01

    The research presented in this doctoral thesis concerns with the development of novel materials and systems for solid state hydrogen storage. The first group of works presented is on alkaline and alkaline-earth borohydrides. The possibility to enhance their properties with the help of nanosupports has been widely explored. An attempt to improve the dehydrogenation kinetics of lithium borohydride has been made dispersing this material on the surface of modified nanotubes and gra...

  11. Solid-state rechargeable magnesium battery

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Yuyan; Liu, Jun; Liu, Tianbiao; Li, Guosheng

    2016-09-06

    Embodiments of a solid-state electrolyte comprising magnesium borohydride, polyethylene oxide, and optionally a Group IIA or transition metal oxide are disclosed. The solid-state electrolyte may be a thin film comprising a dispersion of magnesium borohydride and magnesium oxide nanoparticles in polyethylene oxide. Rechargeable magnesium batteries including the disclosed solid-state electrolyte may have a coulombic efficiency .gtoreq.95% and exhibit cycling stability for at least 50 cycles.

  12. Synthesis and characterization of silver colloidal nanoparticles with different coatings for SERS application

    Energy Technology Data Exchange (ETDEWEB)

    Mikac, L.; Ivanda, M., E-mail: ivanda@irb.hr [Ruđer Bošković Institute, Laboratory for Molecular Physics (Croatia); Gotić, M. [Ruđer Bošković Institute, Laboratory for Synthesis of New Materials (Croatia); Mihelj, T. [Ruđer Bošković Institute, Laboratory for Synthesis and Processes of Self-assembling of Organic Molecules (Croatia); Horvat, L. [Ruđer Bošković Institute, Laboratory for Electron Microscopy (Croatia)

    2014-12-15

    Silver colloids were produced by chemical reduction of silver salt (silver nitrate, AgNO{sub 3}) solution. As reducing agents, trisodium citrate, sodium borohydride, ascorbic acid, polyvinylpyrrolidone, and glucose were used. The colloids were characterized by UV–Vis, DLS, zeta potential measurements, and SEM. The colloids were stabilized with negative groups or large molecules attached to their surface. The surface-enhanced Raman scattering (SERS) effect of stabilized nanoparticles was measured by using pyridine and rhodamine 6G molecules as analytes and NaNO{sub 3}, KCl, and KBr at different concentrations as aggregating agents. The best Raman signal enhancement was achieved using silver nanoparticles of 40 nm size reduced and stabilized with citrate. The SERS signal of analyte molecules was further enhanced with the addition of sodium borohydride as an alternative aggregating agent. The borohydride had the strongest impact on the SERS effect of the colloid consistent of large (0.5 µm) silver nanoparticles stabilized with aminodextran. The mixture colloid-borohydride-pyridine was stable for hours. The mechanism of borohydride in the colloids is discussed.

  13. [Ca(BH4)2] n clusters as hydrogen storage material: A DFT study

    Science.gov (United States)

    Han, Cuiling; Dong, Yanyun; Wang, Bingqiang; Zhang, Caiyun

    2016-10-01

    Calcium borohydride is widely studied as a hydrogen storage material. However, investigations on calcium borohydride from a cluster perspective are seldom found. The geometric structures and binding energies of [Ca(BH4)2] n ( n = 1-4) clusters are determined using density function theory (DFT). For the most stable structures, vibration frequency, natural bond orbital (NBO) are calculated and discussed. The charge transfer from (BH4) to Ca was observed. Meanwhile, we also study the LUMO-HOMO gap ( E g) and the B-H bond dissociation energies (BDEs). [Ca(BH4)2]3 owns higher E g, revealing that trimer is more stable than the other forms. Structures don't change during optimization after hydrogen radical removal, showing that calcium borohydride could possibly be used as a reversible hydrogen storage material. [Ca(BH4)2]4 has the smallest dissociation energy suggesting it releases hydrogen more easily than others.

  14. Amorphous TM1−xBx alloy particles prepared by chemical reduction (invited)

    DEFF Research Database (Denmark)

    Linderoth, Søren; Mørup, Steen

    1991-01-01

    Amorphous transition-metal boron (TM-B) alloy particles can be prepared by chemical reduction of TM ions by borohydride in aqueous solutions. ln the last few years systematic studies of the parameters which control the composition, and, in turn, many of the properties of the alloy particles, have...... been performed and are reviewed in the present paper. The most important preparation parameters which influence the composition are the concentration of the borohydride solution and the pH of the TM salt solution. By controlling these parameters it is possible to prepare amorphous alloy samples...

  15. Properties of amorphous FeCoB alloy particles (abstract)

    DEFF Research Database (Denmark)

    Charles, S. W.; Wells, S.; Meagher, A.;

    1988-01-01

    Amorphous and crystalline alloy particles (0.05–0.5 nm) of FexCoyBz in which the ratio x:y ranges from 0 to 1 have been prepared by the borohydride reduction of iron and cobalt salts in aqueous solution. The structure of the particles has been studied using Mössbauer spectroscopy and x....... 1). It has been shown that the fraction of boron in the alloys (10–35 at. %) is dependent upon the rate of addition of salts to borohydride and the concentration of cobalt present; this in turn influences the crystallinity and magnetic properties . Journal of Applied Physics is copyrighted...

  16. Investigation of nanostructured platinum-nickel supported on the titanium surface as electrocatalysts for alkaline fuel cells

    Science.gov (United States)

    Tamašauskaitė-Tamašiūnaitė, L.; Balčiūnaitė, A.; Vaiciukevičienė, A.; Selskis, A.; Pakštas, V.

    2012-06-01

    This study involves the formation of nanostructured platinum-nickel supported on the titanium surface catalysts using the galvanic displacement technique and investigation of their electrocatalytic activity toward the oxidation of borohydride, methanol and ethanol in an alkaline media by cyclic voltammetry and chronoamperometry. Scanning electron microscopy, Energy Dispersive X-ray Spectroscopy and X-ray diffraction were used to characterize the surface structure, composition and morphology. The nanoPt(Ni)/Ti and nanoPt/Ti catalysts exhibited a higher catalytic efficiency to the oxidation of borohydride, ethanol and methanol as compared with that of pure Pt.

  17. Synthesis and Stabilization of Fe-Nd-B Nanoparticles for Biomedical Applications

    Energy Technology Data Exchange (ETDEWEB)

    Haik, Yousef, E-mail: haik@eng.fsu.edu, E-mail: yhaik@uaeu.ac.ae; Chatterjee, Jhunu; Ching, Jen Chen [Florida State University, Center for Nanomagnetics and Biotechnology (United States)

    2005-12-15

    Stable composition of Iron Neodymium Boron nanoparticles are formed by a chemical method. Conventional borohydride reduction method was used. The particles are in the size range of 30-100 nm. Silica coating was applied to stabilize and prepare the particles for in vitro applications such as cell separation and diagnostics. Morphology of particles has been studied along with the structure and magnetic properties.

  18. Primary structure determination of five sialylated oligosaccharides derived from bronchial- mucus glycoproteins of patients suffering from cystic fibrosis. The occurrence of the NeuAcα(2→3)Galα(1→4)[Fucα(1→3)]GlcNAcα(1→.) structural element revealed by 500-MHz 1H NMR spectroscopy

    NARCIS (Netherlands)

    Vliegenthart, J.F.G.; Lamblin, G.; Boersma, A.; Klein, A.; Roussel, P.; Halbeek, H. van

    1984-01-01

    The structure of sialylated carbohydrate units of bronchial mucins obtained from cystic fibrosis patients was investigated by 500-MHz 1H NMR spectroscopy in conjunction with sugar analysis. After subjecting the mucins to alkaline borohydride degradation, sialylated oligosaccharide-alditols were isol

  19. Structure of three acidic O-linked carbohydrate chains of porcine zona pellucida glycoproteins

    NARCIS (Netherlands)

    Vliegenthart, J.F.G.; Hokke, C.H.; Damm, J.B.L.; Kamerling, J.P.

    1993-01-01

    Structural analysis by ID and 2D 1H NMR spectroscopy of three acidic O-linked oligosaccharide alditols, released from porcine zona pellucida glycoproteins by alkaline borohydride treatment, afforded the following structures: Gal beta l-4(6SO4-)GlcNAc beta l-3Gal beta l-4GlcNAc beta 1-3Gal beta 1-3Ga

  20. The reduction ring-opening reaction of imidazoline

    Institute of Scientific and Technical Information of China (English)

    史真; 李诤; 白银娟

    2000-01-01

    A new reduction ring-opening reaction of 2-imidazoline with sodium borohydride is reported, and the effect of reaction condition on the yield, reaction mechanism and the use of the new reaction in synthesis of ethylenediamine derivatives are discussed. A new method for the preparation of unsymmetrical substituted ethylenediamine via the reduction ring-opening reaction of imidazoline is provided.

  1. Reversibility of Al/Ti Modified LiBH4

    DEFF Research Database (Denmark)

    Blanchard, Didier; Shi, Qing; Boothroyd, Chris;

    2009-01-01

    Lithium borohydride has a high reversible hydrogen storage capacity. For its practical use as an on-board hydrogen storage medium in mobile applications, the temperature and pressure conditions along with the kinetics of the hydrogenation/dehydrogenation cycles have to be improved. Lithium borohy...

  2. Isolation and structural characterization of the smaller-size oligosaccharides from desialylated human κ-casein. Establishment of a novel type of core for a mucin-type carbohydrate chain

    NARCIS (Netherlands)

    Vliegenthart, J.F.G.; Halbeek, H. van; Fiat, A.-M.; Jollès, P.

    1985-01-01

    Alkaline borohydride reductive cleavage (beta-elimination) of desialylated human kappa-caseinoglycopeptide resulted in the release of a series of oligosaccharides. The smaller-size compounds among them were purified to virtual homogeneity by gel filtration followed by high-performance liquid chromat

  3. Structure determination of oligosaccharides isolated from Cad erythrocyte membranes by permethylation analysis and 500-MHz 1H-NMR spectroscopy

    NARCIS (Netherlands)

    Vliegenthart, J.F.G.; Herkt, F.; Paz Parente, J.; Leroy, Y.; Fournet, B.; Blanchard, D.; Cartron, J.-P.; Halbeek, H. van

    1985-01-01

    Alkaline borohydride reductive cleavage (beta-elimination) of glycophorin A isolated from one individual of the rare blood group Cad, resulted in the release of six acidic oligosaccharide-alditols which were separated by high-performance liquid chromatography (HPLC) on an alkyl amine silicagel colum

  4. Direct reduction of some benzoic acids to alcohols via NaBH4-Br2

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Direct reduction of seven benzoic acids to alcohols via sodium borohydride-bromine (NaBH4-Br2) reagent was developed. The isolated yields for the seven acids to reduce reached 60.6-90.1 %. This new synthesis route has the advantages of simple of application, low cost, mild nature, and satisfactory yields.

  5. Measurement of the Isotopic Ratio of [to the tenth power]B/[to the eleventh power]B in NaBH[subscript 4] by [to the first power]H NMR

    Science.gov (United States)

    Zanger, Murray; Moyna, Guillermo

    2005-01-01

    A study uses nuclear magnetic resonance (NMR) spectroscopy in a novel way to determine the isotopic ration between [to the tenth power]B and [to the eleventh power]B in sodium borohydride (NaBH4). The experiment provides an unusual and relatively simple means for undergraduate chemistry students to accurately measure the distribution of the two…

  6. 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

  7. Easy access to 6-membered iminoalditols - important glycosidase inhibitors

    DEFF Research Database (Denmark)

    Lundt, Inge

    of 6-membered iminoalditols were observed. The use of triethylamine in methanol thus gave methylesters of 6-membered iminouronic acids. Reduction of the ester group with sodium borohydride gave the target compounds. The mechanisms of the reactions will be discussed as well as specific results obtained...

  8. Practical reduction of imines by NaB H4/alumina under solvent-free conditions:An efficient route to secondary amine

    Institute of Scientific and Technical Information of China (English)

    Foad Kazemi; Ali Reza Kiasat; Ebrahim Sarvestani

    2008-01-01

    Sodium borohydride supported on alumina reduces imines to the corresponding secondary amines in high to excellent isolated yields under solvent-free conditions.Noteworthy is that highly chemoselective reactions were achieved in the presence of other functional groups such as halogen,nitro,and cyano groups.

  9. The fabrication and option characteristics of polyethylene glycol-coated gold nanoparticles with different size

    International Nuclear Information System (INIS)

    Objective: To synthesize gold nanoparticles (GNPs) and polyethylene glycol-coated GNPs (PEG-GNPs)modified by sulfhydryl-polyethylene glycol (SH-PEG), chloroauric acid and different reductant agent,such as trisodium citrate and sodium borohydride were used. Methods: Chloroauric acid solution was brought to a boil,and then different volume of trisodium citrate solution or sodium borohydride solution was added to the boiling solution. Then the mixture was boiled for a further 30 minutes. Subsequently some SH-PEG was mixed with the GNPs and stirred for 1 hour to fabricate the PEG-GNPs. The optical characteristic and size of GNPs and PEG-GNPs were observed by UV-Vis spectrophotometer and transmission electron microscopic respectively. Results: 10, 25, and 45 nm GNPs were fabricated using 1% trisodium citrate,while the 5 nm GNPs were synthesized using 0.11% sodium borohydride. Meanwhile, SH-PEG was added to the GNPs and obtained the PEG-GNPs. Furthermore, when compared with the GNPs with different size,it can be found that the surface plasmon resonance (SPR) of GNPs have shift to long wavelength region with increasing particles size. The same phenomenon also can be found in the PEG-GNPs with different size. Conclusions: The size of GNPs can be modulated by controlling the ratio between chloroauric acid and trisodium citrate or sodium borohydride. Meanwhile, the larger the size of GNPs is, the more significant of the shifting to the long wavelength of SPR is. (authors)

  10. Development of Hydrogen Storage Tank Systems Based on Complex Metal Hydrides

    Directory of Open Access Journals (Sweden)

    Morten B. Ley

    2015-09-01

    Full Text Available This review describes recent research in the development of tank systems based on complex metal hydrides for thermolysis and hydrolysis. Commercial applications using complex metal hydrides are limited, especially for thermolysis-based systems where so far only demonstration projects have been performed. Hydrolysis-based systems find their way in space, naval, military and defense applications due to their compatibility with proton exchange membrane (PEM fuel cells. Tank design, modeling, and development for thermolysis and hydrolysis systems as well as commercial applications of hydrolysis systems are described in more detail in this review. For thermolysis, mostly sodium aluminum hydride containing tanks were developed, and only a few examples with nitrides, ammonia borane and alane. For hydrolysis, sodium borohydride was the preferred material whereas ammonia borane found less popularity. Recycling of the sodium borohydride spent fuel remains an important part for their commercial viability.

  11. Studies on the preparation of labelled compounds for γ-scintigraphy use

    International Nuclear Information System (INIS)

    To develop 99mTc instant labelling kit of d,1-HMPAO and 131I labelled IMP for the regional cerebral blood flow scintigraphic use, d,1-HMPAO and IMP were synthesized. The former was prepared from 2,3-butadione monoxim and 2,2-dimethyl-1,3-propanediamine in the presence of cation exchange resin, and then selective reduction of imine bond with sodium borohydride followed by fractional crystallization of diastereometric mixture of HMPAO. The latter was prepared by condensation of p-iodophenylpropanone with isopropylamine, and then reduction of double bond with sodium borohydride. For the preparation of 99mTc labelled HSA, experiments on incorporation of bifunctional chelating agent of DTPA to HSA, establishment of optimal conditions of 99mTc labelling, determination of labelling yield and radiochemical purity, and examination of stability were carried out. (Author)

  12. Tailoring Thermodynamics and Kinetics for Hydrogen Storage in Complex Hydrides towards Applications.

    Science.gov (United States)

    Liu, Yongfeng; Yang, Yaxiong; Gao, Mingxia; Pan, Hongge

    2016-02-01

    Solid-state hydrogen storage using various materials is expected to provide the ultimate solution for safe and efficient on-board storage. Complex hydrides have attracted increasing attention over the past two decades due to their high gravimetric and volumetric hydrogen densities. In this account, we review studies from our lab on tailoring the thermodynamics and kinetics for hydrogen storage in complex hydrides, including metal alanates, borohydrides and amides. By changing the material composition and structure, developing feasible preparation methods, doping high-performance catalysts, optimizing multifunctional additives, creating nanostructures and understanding the interaction mechanisms with hydrogen, the operating temperatures for hydrogen storage in metal amides, alanates and borohydrides are remarkably reduced. This temperature reduction is associated with enhanced reaction kinetics and improved reversibility. The examples discussed in this review are expected to provide new inspiration for the development of complex hydrides with high hydrogen capacity and appropriate thermodynamics and kinetics for hydrogen storage. PMID:26638824

  13. Synthesis and characterization of poly(pyrazolyl)borate tantalum amide complexes and their reactivities toward oxygen

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Reaction of TaCl(NMe2)4 (1) with KTp* [Tp* = tris(3,5-dimethylpyrazolyl)borohydride] yields two products: Tp*Ta(NMe2)4 (2), in which one N atom of the Tp* ligand binds to Ta, and [Tp*Ta(NMe2)4]· 2KTp* (3) where three N atoms of the Tp* ligand in [Tp*Ta(NMe2)4] (2a) bind to Ta. Addition of excess 1 to 3 did not exclude KTp*. Further reaction of 2 with oxygen affords Tp*BH(NMe2) (4). TpTa(NMe2)4 (5) has been synthesized by a similar procedure through the reaction of 1 with TpK [Tp=tris(pyrazolyl)borohydride]. Reactions of 3 and 5 with oxygen were also studied. 2, 4, and 5 were characterized by NMR, EA, and single-crystal X-ray diffraction.

  14. Platinum- and membrane-free swiss-roll mixed-reactant alkaline fuel cell.

    Science.gov (United States)

    Aziznia, Amin; Oloman, Colin W; Gyenge, Előd L

    2013-05-01

    Eliminating the expensive and failure-prone proton exchange membrane (PEM) together with the platinum-based anode and cathode catalysts would significantly reduce the high capital and operating costs of low-temperature (monolithic carbon fiber materials (referred to as an osmium 3D anode). The borohydride-oxygen SR-MRFC operates at 323 K and near atmospheric pressure, generating a peak power density of 1880 W m(-2) in a single-cell configuration by using an osmium-based anode (with an osmium loading of 0.32 mg cm(-2)) and a manganese dioxide gas-diffusion cathode. To the best of our knowledge, 1880 W m(-2) is the highest power density ever reported for a mixed-reactant fuel cell operating under similar conditions. Furthermore, the performance matches the highest reported power densities for conventional dual chamber PEM direct borohydride fuel cells. PMID:23589385

  15. Role of Ti doping and Al and B vacancies in the dehydrogenation of Al(BH₄)₃

    Indian Academy of Sciences (India)

    INDRANI CHOUDHURI; ARUP MAHATA; KUBER SINGH RAWAT; BISWARUP PATHAK

    2016-10-01

    Metal borohydrides such as Al(BH₄)₃ is thermodynamically very stable but has weak dehydrogenation property. In contrast, Ti(BH₄)₃ has less stability (25◦C) but excellent dehydrogenation property. Hence, we have studied Ti-doped aluminium borohydride systems in order to improve the dehydrogenation property. Our density functional studies (DOS and pDOS) show that Ti interacts more strongly with the BH₄ unit and such strong interaction weakens the B-H bond and improves the dehydrogenation property. Ti-doped Al(BH₄)₃ system improves the overall stability due to the formation of a stronger Ti-B bond. Our study on defects in Al(BH₄)₃ suggests that B-defect system has the best dehydrogenation property compared to the pure and Ti-doped Al(BH₄)₃ systems.

  16. Uranium isotope separation in the solid state. Final report for period ending September 30, 1978

    International Nuclear Information System (INIS)

    The final results of an investigation on the isotope separation of uranium in the solid state are presented in this report. The feasibility of separating uranium isotopes using the proposed system based on uranium borohydride (borodeuteride) in a low temperature mixed crystal has been determined. The first section of the report summarizes the background material relating to this work which includes: a calculation of isotope shifts (borodeuteride), details on the two-step, two-photon spectroscopic isotope separation technique, and a brief overview of the method and equipment used for separating uranium isotopes in the solid state. The second section concerns the experimental details of the present work performed in the laboratory. Representative spectroscopic data obtained in this investigation are presented and discussed in the third section. Finally, the report is concluded with recommendations for further investigations on the uranium borohydride (borodeuteride) system for isotope separation

  17. Synthesis and Thermal Behavior of Metallic Cobalt Micro and Nanostructures

    Institute of Scientific and Technical Information of China (English)

    Marlene Gonzalez Montiel; P Santiago-Jacinto; J A I Daz Gongora; E Reguera; Geonel Rodrguez-Gattorno

    2011-01-01

    In this contribution, a comparative study of metallic cobalt micro and nanoparticles obtained in solution by four different chemical routes is reported. Classic routes such as borohydride reduction in aqueous media and the so-called polyol methodology were used to obtain the cobalt nanostructures to be studied. Using CTAB as surfactant, cobalt hollow nanostructures were obtained. The use of strong reducing agents, like sodium borohydride, favors the formation of quasi-monodispersed nanoparticles of about 2 nm size but accompanied with impurities; for hydrazine (a mild reducer), nanoparticles of larger size are obtained which organize in spherical microagglomerates. Valuable information on the particles thermal stability and on nature of the species anchored at their surface was obtained from thermogravimetric curves. The samples to be studied were characterized from UV-vis, IR, X-ray diffraction, and electron microscopy images (scanning and transmission).

  18. Camphor-mediated synthesis of carbon nanoparticles, graphitic shell encapsulated carbon nanocubes and carbon dots for bioimaging

    OpenAIRE

    Goldie Oza; Ravichandran, M.; Victor-Ishrayelu Merupo; Sachin Shinde; Ashmi Mewada; Jose Tapia Ramirez; Velumani, S.; Madhuri Sharon; Maheshwar Sharon

    2016-01-01

    A green method for an efficient synthesis of water-soluble carbon nanoparticles (CNPs), graphitic shell encapsulated carbon nanocubes (CNCs), Carbon dots (CDs) using Camphor (Cinnamomum camphora) is demonstrated. Here, we describe a competent molecular fusion and fission route for step-wise synthesis of CDs. Camphor on acidification and carbonization forms CNPs, which on alkaline hydrolysis form CNCs that are encapsulated by thick graphitic layers and on further reduction by sodium borohydrid...

  19. Efficient synthesis of 1,3,5-oxygenated synthons from dimethyl 3-oxoglutarate: first use of borane-dimethyl sulfide complex as a regioselective reducing agent of 3-oxygenated glutarate derivatives

    International Nuclear Information System (INIS)

    The selective reduction of dimethyl 3-oxoglutarate was accomplished in different levels. A high yielding sodium borohydride reduction of the keto group is fully described leading to dimethyl 3-hydroxyglutarate. When borane-dimethyl sulfide (BMS) complex was used, a diol or a triol compound can be obtained by selective or total reduction of 3-hydroxy- or 3-oxoglutarate, respectively, allowing an efficient and practical route to 1,3,5-oxygenated compounds. (author)

  20. One Pot Reduction of Imines Generated in-situ from Aldehydes and Amines by the NaBH4-InCl3 System

    Institute of Scientific and Technical Information of China (English)

    RAVI Varala; RAMU Enugala; VIJAY KUMAR Ponnamaneni; SRINIVAS RAO Adapa

    2006-01-01

    A combination of sodium borohydride and a catalytic amount of indium(Ⅲ) chloride in acetonitrile reduces imines formed in-situ from aldehydes and amines to the corresponding functionalised secondary and tertiary amines in moderate to good yields. Noteworthy is that highly chemoselective reactions were achieved in the presence of other functional groups such as halogens, carbon-carbon double bonds and hydroxyl groups.

  1. A Study of Groundwater Matrix Effects for the Destruction of Trichloroethylene Using Fe/Pd Nanoaggregates

    Energy Technology Data Exchange (ETDEWEB)

    meyer, D E [Univ of KY, dept of chemical and materials engineering; Hampson, Steve [Univ of KY Center for Applied Energy Research - Ky Research Consortium of Energy and Environment; ormsbee, Lindelle [Univ of KY Center for Applied Energy Research - Ky Research Consortium of Energy and Environment; Bhattacharyya, Dibakar [univ of KY, Dept of Chemical and Materials Engineering

    2008-06-01

    Fe nanoaggregates have been prepared using the sodium borohydride reduction method and post-coated with Pd using aqueous phase electro-depostition. The Fe/Pd particles have been used to examine dechlorination of TCE with regard to matrix effects using materials representative of examine dechlorination of TCE with regard to matrix effects using materials representative of a potential zero-valent metal remediation site surrounding the Paducah Gaseous Diffusion Plant in Paducah, KY.

  2. Synthesis of radiolabelled clenbuterol analogues

    Energy Technology Data Exchange (ETDEWEB)

    Pegg, G.C.; Sleeman, M.J. (University College of Central Queensland, Rockhampton, M.C. (Australia). Dept. of Chemistry); Sillence, M.N.; Lindsay, D.B. (Commonwealth Scientific and Industrial Research Organization, North Rockhampton, Queensland (Australia). Tropical Cattle Research Ccentre)

    1991-12-01

    Oxidation of clenbuterol with pyridinium chlorochromate yielded 4-amino-3,5-dichloro-{alpha}-tert.-butylaminoacetophenone 5. Tritiated clenbuterol was produced by reduction of 5 with sodium ({sup 3}H)borohydride. Radioiodination of the clenbuterol precursor (2-tert.-butylamino-1-(4-aminophenyl)-ethanol) yielded (2-tert.-butylamino-1-(4-amino-3-({sup 125}I) iodophenyl)-ethanol). (author).

  3. Effect of experimentally induced reducing conditions on the mobility of arsenic from a mining soil

    Energy Technology Data Exchange (ETDEWEB)

    Chatain, Vincent [Laboratoire d' Analyse Environnementale des Procedes et des Systemes Industriels, Institut National des Sciences Appliquees de Lyon, 20 Avenue Albert Einstein, 69621 Villeurbanne Cedex (France); Sanchez, Florence [Department of Civil and Environmental Engineering, Vanderbilt University, Station B-35 1831, Nashville, TN 37235 (United States)]. E-mail: Florence.sanchez@Vanderbilt.edu; Bayard, Remy [Laboratoire d' Analyse Environnementale des Procedes et des Systemes Industriels, Institut National des Sciences Appliquees de Lyon, 20 Avenue Albert Einstein, 69621 Villeurbanne Cedex (France); Moszkowicz, Pierre [Laboratoire d' Analyse Environnementale des Procedes et des Systemes Industriels, Institut National des Sciences Appliquees de Lyon, 20 Avenue Albert Einstein, 69621 Villeurbanne Cedex (France); Gourdon, Remy [Laboratoire d' Analyse Environnementale des Procedes et des Systemes Industriels, Institut National des Sciences Appliquees de Lyon, 20 Avenue Albert Einstein, 69621 Villeurbanne Cedex (France)

    2005-06-30

    A method for estimating the release of contaminants from contaminated sites under reducing conditions is proposed. The ability of two chemical reducing agents, sodium ascorbate and sodium borohydride, to produce different redox environments in a gold mining soil contaminated with arsenic was investigated. Liquid-solid partitioning experiments were carried out in the presence of each of the reducing agents at different pH conditions. Both the effect of varying concentrations of the reducing agent and the effect of varying pH in the presence of a constant concentration of the reducing agent were studied. Concentrations of sodium ascorbate ranging from 0.0075 to 0.046 mol L{sup -1} and concentrations of sodium borohydride ranging from 0.0075 to 0.075 mol L{sup -1} were examined. The addition of varying concentrations of sodium borohydride provided greater reducing conditions (ranging from -500 to +140 mV versus NHE) than that obtained using sodium ascorbate (ranging from -7 to +345 mV versus NHE). The solubilization of arsenic and iron was significantly increased by the addition of sodium ascorbate for all concentrations examined and pH tested, compared to that obtained under oxidizing conditions (as much as three orders of magnitude and four orders of magnitude, respectively, for the addition of 0.046 mol L{sup -1} of sodium ascorbate). In contrast, the alkaline and highly reduced soil conditions obtained with sodium borohydride lead to a lower effect on arsenic solubilization (as much as one order of magnitude for pH values between ca. 7 and 10 and no effect for pH values between ca. 10 and 12) and no effect on iron solubilization for all concentrations examined and pH tested. At similar ORP-pH conditions the results of extraction for arsenic and iron were different for the two reagents used.

  4. Green Synthesis of Ag and Pd Nanospheres, Nanowires, and Nanorods Using Vitamin B2: Catalytic Polymerisation of Aniline and Pyrrole

    OpenAIRE

    Mallikarjuna N. Nadagouda; Varma, Rajender S.

    2008-01-01

    For the first time, we report green chemistry approach using vitamin B2 in the synthesis of silver (Ag) and palladium (Pd), nanospheres, nanowires, and nanorods at room temperature without using any harmful reducing agents, such as sodium borohydride (NaBH4) or hydroxylamine hydrochloride and any special capping or dispersing agent. Vitamin B2 was used as reducing agent as well as capping agent due to its high-water solubility, biodegradability, and low-toxicity compared with other reducing a...

  5. Alkaline phosphatase for immunocytochemical labelling: problems with endogenous enzyme activity.

    OpenAIRE

    Bulman, A. S.; Heyderman, E

    1981-01-01

    Alkaline phosphatase may be used as a label for immunocytochemistry and can be demonstrated in tissue sections using the single step naphthol phosphate method. Endogenous enzyme activity may not be destroyed by fixation in formalin, formol alcohol, Carnoy's or Baker's solutions and should be inhibited before results are assessed. Either Bouin's solution or periodic acid followed by potassium borohydride are satisfactory inhibitor and do not adversely affect immunocytochemical results.

  6. $sup 3$H-metyrapol as a tool for studies of interactions of deoxycorticosterone with adrenal cortex mitochondria

    Energy Technology Data Exchange (ETDEWEB)

    Satre, M.; Lunardi, J.; Vignais, P.V.

    1972-05-01

    From international conference on mechanism in bioenergetica; Bari, Italy (1 May 1972). /sup 3/H-metyrapol was prepared by reduction of metyrapone with tritiated sodium borohydride. Metyrapol behaves like metyrapone as an inhibitor of the 11 BETA -hydroxylation of deoxycorticosterone in adrenal cortex mitochondria and competes with metyrapone in binding tests. These results, and the ease of preparation of highly labeled /sup 3/H-metyrapol, recommend /sup 3/ Hmetyrapol as a probe of deoxycorticosterone interactions with adrenal cortex mitochondria. (auth)

  7. Technetium-99m labeling of tityustoxin and venom from the scorpion Tityus serrulatus

    International Nuclear Information System (INIS)

    The tityustoxin, the most toxic fraction from scorpion Tityus serrulatus venom, has been used as a tool in several neurochemical and neuropharmacological studies. Biological activities of labeled and unlabeled tityustoxin and venom were compared. The samples were labeled in the presence of stannous chloride and sodium borohydride with a yield of 60-70% for the venom and 75-85% for tityustoxin and then chromatographed in Sephadex G-10. Biological activities of tityustoxin and venom were preserved after labeling

  8. The heating effect of iron-cobalt magnetic nanofluids in an alternating magnetic field: application in magnetic hyperthermia treatment

    OpenAIRE

    Shokuhfar, Ali; Seyyed Afghahi, Seyyed Salman

    2013-01-01

    In this research, FeCo alloy magnetic nanofluids were prepared by reducing iron(III) chloride hexahydrate and cobalt(II) sulfate heptahydrate with sodium borohydride in a water/CTAB/hexanol reverse micelle system for application in magnetic hyperthermia treatment. X-ray diffraction, electron microscopy, selected area electron diffraction, and energy-dispersive analysis indicate the formation of bcc-structured iron-cobalt alloy. Magnetic property assessment of nanoparticles reveals that some s...

  9. Structural Characterization and Mechanical Properties of As-plated and Heat Treated Electroless Ni-B-P Alloy Coatings

    Directory of Open Access Journals (Sweden)

    P. G. Venkatakrishnan

    2014-05-01

    Full Text Available The Ni-B-P alloy coatings were made autocatalytically (electroless using an alkaline plating bath with nickel chloride hexahydrate (NiCl2.6H2O as the source of nickel ions, sodium borohydride (NaBH4 and sodium hypophosphite (NaH2PO2 as reducing agents and source of boron and phosphorous ions, respectively. The effects of bath concentrations on the plating rate, composition of coating, surface morphology, structural features and microhardness have been studied by varying NaBH4 concentration in the plating bath from 0.2 to 0.8 g/l while keeping NaH2PO2 concentration constant (12 g/l. The plating rate and boron content of the electroless Ni-B-P ternary alloy coatings increased with increasing NaBH4 concentration in the plating bath. The scanning electron microscopic images revealed that the morphology of the coating changed from corn cob structure to coarse cauliflower structure with increasing borohydride concentration in the plating bath. Broadening of X-ray diffraction peak is observed, as the borohydride concentration is increased in the plating bath, which is attributed to the large reduction in the crystallite size of the Ni-B-P alloy coatings. The microhardness values of the coating increased with increasing borohydride concentration in the plating bath. The as-plated Ni-B-P alloy coating containing higher boron content (3.2 wt% shows higher hardness of 700 HV compared to other Ni-B-P alloy coatings. The XRD patterns of heat treated Ni-B-P alloy coatings (500 °C show Ni3B intermetallic peaks along with Ni peaks. The presence of Ni3B intermetallic compound significantly increases the microhardness values of the heat treated Ni-B-P alloy coatings.

  10. Influence of the Synthesis Method for Pt Catalysts Supported on Highly Mesoporous Carbon Xerogel and Vulcan Carbon Black on the Electro-Oxidation of Methanol

    OpenAIRE

    Cinthia Alegre; María Elena Gálvez; Rafael Moliner; María Jesús Lázaro

    2015-01-01

    Platinum catalysts supported on carbon xerogel and carbon black (Vulcan) were synthesized with the aim of investigating the influence of the characteristics of the support on the electrochemical performance of the catalysts. Three synthesis methods were compared: an impregnation method with two different reducing agents, sodium borohydride and formic acid, and a microemulsion method, in order to study the effect of the synthesis method on the physico-chemical properties of the catalysts. X-ra...

  11. Efficient synthesis of 1,3,5-oxygenated synthons from dimethyl 3-oxoglutarate: first use of borane-dimethyl sulfide complex as a regioselective reducing agent of 3-oxygenated glutarate derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Riatto, Valeria B.; Carneiro, Maria N.M.; Victor, Mauricio M., E-mail: mmvictor@ufba.b [Universidade Federal da Bahia (IQ/UFBA), Salvador, BA (Brazil). Inst. de Quimica. Dept. de Quimica Organica; Carvalho, Venilia B. [Centro Universitario FIB, Salvador, BA (Brazil). Inst. de Ciencias da Saude

    2011-07-01

    The selective reduction of dimethyl 3-oxoglutarate was accomplished in different levels. A high yielding sodium borohydride reduction of the keto group is fully described leading to dimethyl 3-hydroxyglutarate. When borane-dimethyl sulfide (BMS) complex was used, a diol or a triol compound can be obtained by selective or total reduction of 3-hydroxy- or 3-oxoglutarate, respectively, allowing an efficient and practical route to 1,3,5-oxygenated compounds. (author)

  12. Silver/poly (lactic acid) nanocomposites: preparation, characterization, and antibacterial activity

    OpenAIRE

    Shameli, Kamyar; Ahmad, Mansor Bin; Yunus, Wan Md Zin Wan; Ibrahim, Nor Azowa; Rahman, Russly Abdul; Jokar, Maryam; Darroudi, Majid

    2010-01-01

    In this study, antibacterial characteristic of silver/poly (lactic acid) nanocomposite (Ag/PLA-NC) films was investigated, while silver nanoparticles (Ag-NPs) were synthesized into biodegradable PLA via chemical reduction method in diphase solvent. Silver nitrate and sodium borohydride were respectively used as a silver precursor and reducing agent in the PLA, which acted as a polymeric matrix and stabilizer. Meanwhile, the properties of Ag/PLA-NCs were studied as a function of the Ag-NP weig...

  13. 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.

  14. Etude de l'anode pour la pile à combustible directe aux borohydrures

    OpenAIRE

    Olu, Pierre-Yves

    2015-01-01

    The present work focuses on direct borohydride fuel cell (DBFC) anodes. A first approach to develop a suitable anode design for the DBFC consists in the study of the anode within the real DBFC system. In that frame, carbon-supported platinum and palladium nanoparticles are characterized and compared as anode electrocatalyst in DBFC configuration. Other variables such as the morphology of the anode and the stability of the catalyst nanoparticles are considered.The ideal DBFC anode catalyst sho...

  15. Synthesis of Ca(BH4)2 from Synthetic Colemanite Used in Hydrogen Storage by Mechanochemical Reaction

    Science.gov (United States)

    Karabulut, Ahmet F.; Guru, Metin; Boynueğri, Tuğba A.; Aydin, Mustafa Yasir

    2016-08-01

    In this study, synthesis of Ca(BH4)2 has been carried out with a solid phase reaction in which synthetic colemanite has been used as a raw material. Three dimensional high energy spex collider was selected for this mechanochemical reaction. Calcium borohydride is one of the most valuable metal borohydrides. In order to produce calcium borohydride economically, anhydrous colemanite mineral has been used as reactant. Calcium borohydride has been directly manufactured from anhydrous colemanite in spex-type ball milling without the need for any intermediate product. Thus, the advantages of this method over wet chemical procedure (such as having no intermediate product, no azeotropic limitations and no need of regaining product from solution after production by using evaporation, crystallization and drying processes) have made it possible to achieve the desired economical gains. Parametric experiments were conducted to determine the best conditions for the highest yield of solid phase reaction in the spex-type ball milling. Best results have been determined by using areas of related peaks in spectra of Fourier transform infrared spectroscopy (FT-IR). In order to use peaks area for determining Ca(BH4)2 concentration, a calibration graph of FT-IR absorbance peak areas has been created by using samples with known different concentrations of commercial Ca(BH4)2. Optimum amounts of calcium hydride and synthesis reaction time were found to be 2.1 times the stoichiometric ratio and 2500 min, respectively. As a result of these optimizations, the maximum yield of the solid phase reaction carried out by the spex-type ball milling has been determined as 93%.

  16. Preparation of 2-deoxyaldoses from aldose phenylhydrazones

    DEFF Research Database (Denmark)

    Jørgensen, Christel Thea; Pedersen, Christian

    1997-01-01

    Acetylation of D-mannose phenylhydrazone gives acetylated D-arabino-1-phenyl-azo-1-(E)-hexene. Subsequent reduction with sodium borohydride produces 2-deoxy-D-arabino-hexose phenylhydrazone which, on hydrolysis, gives 2-deoxy-D-arabino-hexose. By a similar procedure 2-deoxy-D-lyxo-hexose, 2,6-did......,6-dideoxy-L-arabino-hexose, and 2-deoxy-D-erythropentose can be prepared from D-galactose, L-rhamnose, and D-arabinose, respectively....

  17. Increasing Hydrogen Density with the Cation-Anion Pair BH4−-NH4+ in Perovskite-Type NH4Ca(BH43

    Directory of Open Access Journals (Sweden)

    Pascal Schouwink

    2015-08-01

    Full Text Available A novel metal borohydride ammonia-borane complex Ca(BH42·NH3BH3 is characterized as the decomposition product of the recently reported perovskite-type metal borohydride NH4Ca(BH43, suggesting that ammonium-based metal borohydrides release hydrogen gas via ammonia-borane-complexes. For the first time the concept of proton-hydride interactions to promote hydrogen release is applied to a cation-anion pair in a complex metal hydride. NH4Ca(BH43 is prepared mechanochemically from Ca(BH42 and NH4Cl as well as NH4BH4 following two different protocols, where the synthesis procedures are modified in the latter to solvent-based ball-milling using diethyl ether to maximize the phase yield in chlorine-free samples. During decomposition of NH4Ca(BH43 pure H2 is released, prior to the decomposition of the complex to its constituents. As opposed to a previously reported adduct between Ca(BH42 and NH3BH3, the present complex is described as NH3BH3-stuffed α-Ca(BH42.

  18. Boron-Based Hydrogen Storage: Ternary Borides and Beyond

    Energy Technology Data Exchange (ETDEWEB)

    Vajo, John

    2016-09-22

    DOE continues to seek reversible solid-state hydrogen materials with hydrogen densities of ³11 wt% and ³80 g/L that can deliver hydrogen and be recharged at moderate temperatures (£100 °C) and pressures (£100 bar) enabling incorporation into hydrogen storage systems suitable for transportation applications. Boron-based hydrogen storage materials have the potential to meet the density requirements given boron’s low atomic weight, high chemical valance, and versatile chemistry. However, the rates of hydrogen exchange in boron based compounds are thus far much too slow for practical applications. Although contributing to the high hydrogen densities, the high valance of boron also leads to slow rates of hydrogen exchange due to extensive boron-boron atom rearrangements during hydrogen cycling. This rearrangement often leads to multiple solid phases occurring over hydrogen release and recharge cycles. These phases must nucleate and react with each other across solid-solid phase boundaries leading to energy barriers that slow the rates of hydrogen exchange. This project sought to overcome the slow rates of hydrogen exchange in boron-based hydrogen storage materials by minimizing the number of solid phases and the boron atom rearrangement over a hydrogen release and recharge cycle. Two novel approaches were explored: 1) developing matched pairs of ternary borides and mixed-metal borohydrides that could exchange hydrogen with only one hydrogenated phase (the mixed-metal borohydride) and only one dehydrogenated phase (the ternary boride); and 2) developing boranes that could release hydrogen by being lithiated using lithium hydride with no boron-boron atom rearrangement. For the first approach, possible pairs of ternary borides and mixed-metal borohydrides based on Mg with various first row transition metals were investigated both experimentally and theoretically. In particular, the Mg/Mn ternary boride and mixed-metal borohydride were found to be a suitable pair and

  19. 基于聚丙烯腈碳毡电极的偏硼酸钠电解行为研究%Study on Electrolytic Behavior of Sodium Metaborate Based on Polyacrylonitrile Felt Electrode

    Institute of Scientific and Technical Information of China (English)

    戴玺; 郭瓦力; 张弢; 李磊; 王晓冰; 朱虹; 邓信忠

    2013-01-01

    The feasibility of using polyacrylonitrile carbon felt electrode for sodium borohydride preparation from sodium metaborate electrolysis was studied by means of cyclic voltammetry. Effects of the felt electrode on electrolysis reaction were investigated under constant current or pulsed conditions,in which the actual production of sodium borohydride was taken as an experiment indicator. Considering the physical properties of carbon felt electrode,the effects of electrolysis reaction according to the age of polyacrylonitrile felt electrode and the sodium borohydride concentration difference between the electrolytes both in electrode pore and in electrolytic cell were also discussed. The results show that the unique physical structure of carbon felt electrode can be used to solve the problem of BO2-exclusion on cathode well, which plays an important role in promoting BO2-cathode restore to generate sodium borohydride. Because of the electrode repulsion and carbon fiber felt adsorption force acting on the BO2-reduction on the cathode,there is a maximum value of sodium borohydride production to some extent of current intensity.Compared with the electrolyte in electrolytic cell, the content of sodium borohydride in the pores of the carbon felt can be 22.7 times as much as the content in the electrolyzer.%  通过循环伏安法研究了聚丙烯腈碳毡电极用于电解法硼氢化钠制备的可行性,以硼氢化钠实际生成量为指标,研究了在恒流,脉冲条件下碳毡电极对电解反应生成量的影响,针对碳毡电极本身的物理特性考察了碳毡的新旧程度对电解反应的影响,考察了电极孔隙电解液和电解槽中电解液中硼氢化钠生成量的差别。研究结果表明:碳毡电极独特的物理结构改善了阴极对BO2-排斥,对BO2-在阴极上发生还原生成硼氢化钠有很好的促进作用;电极排斥力与碳毡吸附力共同作用于阴极上的BO2-还原,因此一定电流强度

  20. Snythesis of 3-methy-1-lamino phenyl alcohol by microwave radiation%3-甲胺基-1-苯基丙醇的微波合成

    Institute of Scientific and Technical Information of China (English)

    吴海燕

    2012-01-01

    The synthesis method of 3- methylamino -1-phenyl acetone ( 1 )is acetophenone and methylamine hydrochloride, paraformaldehyde by microwave; The preparation 3- methylamino-1- phenylpropanol(2) is(l) reduction by sodium borohydride in methanol.%苯乙酮与甲胺盐酸盐、多聚甲醛用微波法合成3-甲胺基-1-苯基丙酮(1);(1)在甲醇中用硼氢化钠还原制备3-甲胺基-1-苯基丙醇(2).

  1. Complex hydrides for hydrogen storage – new perspectives

    Directory of Open Access Journals (Sweden)

    Morten B. Ley

    2014-04-01

    Full Text Available Since the 1970s, hydrogen has been considered as a possible energy carrier for the storage of renewable energy. The main focus has been on addressing the ultimate challenge: developing an environmentally friendly successor for gasoline. This very ambitious goal has not yet been fully reached, as discussed in this review, but a range of new lightweight hydrogen-containing materials has been discovered with fascinating properties. State-of-the-art and future perspectives for hydrogen-containing solids will be discussed, with a focus on metal borohydrides, which reveal significant structural flexibility and may have a range of new interesting properties combined with very high hydrogen densities.

  2. Excimer laser photofragmentation of metallic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Badr, Y. [National Institute of Laser Enhanced Science, Cairo University, Cairo (Egypt); Mahmoud, M.A. [Chemistry Department, Faculty of Science, Zagazig University, Zagazig (Egypt)], E-mail: mahmoudchem@yahoo.com

    2007-10-15

    Copper nanoparticles (Cu NPs) were prepared by different chemical methods possessing different sizes. While, silver nanoparticles (Ag NPs) were prepared by borohydride reduction method. The influences the changes in sizes of Ag NPs and Cu NPs were demonstrated by the absorption spectra. When Ag NPs and Cu NPs irradiated with 193 and 308 nm excimer laser, respectively; the maximum absorption decreased as the number of pulses increased up to 10 thousands pulse; due to the size reduction. The TEM photography gives good criteria about the size reduction process. Moreover, the mechanism of photofragmentation was described.

  3. Nanoconfined LiBH4 as a Fast Lithium Ion Conductor

    DEFF Research Database (Denmark)

    Blanchard, Didier; Nale, Angeloclaudio; Sveinbjörnsson, Dadi Þorsteinn;

    2015-01-01

    Designing new functional materials is crucial for the development of efficient energy storage and conversion devices such as all solid-state batteries. LiBH 4 is a promising solid electrolyte for Li-ion batteries. It displays high lithium mobility, although only above 110 °C at which a transition...... is associated with a fraction of the confined borohydride that shows no phase transition, and most likely located close to the interface with the SiO2 pore walls. These results point to a new strategy to design low-temperature ion conducting solids for application in all solid-state lithium ion batteries, which...

  4. Directed magnetic field induced assembly of high magnetic moment cobalt nanowires

    DEFF Research Database (Denmark)

    Srivastava, Akhilesh Kumar; Madhavi, S.; Ramanujan, R.V.

    2010-01-01

    A directed magnetic field induced assembly technique was employed to align two phase (h.c.p. + f.c.c.) cobalt nanoparticles in a mechanically robust long wire morphology. Co nanoparticles with an average size of 4.3 nm and saturation magnetization comparable to bulk cobalt were synthesized...... by borohydride reduction followed by size selection and magnetic field induced assembly. The coercivity of these nanowires was higher than their nanoparticle counterpart due to shape anisotropy. The experimental coercivity values of the nanowires were lower than the predictions of the coherent rotation, fanning...

  5. Quantum size effects in the volume plasmon excitation of bismuth nanoparticles investigated by electron energy loss spectroscopy

    Science.gov (United States)

    Wang, Y. W.; Kim, J. S.; Kim, G. H.; Kim, Kwang S.

    2006-04-01

    Quantum size effects in volume plasmon excitation of bismuth nanoparticles with diameters ranging from 5to500nm have been studied by electron energy loss spectroscopy. The Bi nanoparticles were prepared by reducing Bi3+ with sodium borohydride in the presence of poly(vinylpyrroldone). The volume plasmon energy and its peak width increase with decreasing nanoparticle diameter, due to the quantum size effect. For the particles with diameter less than 40nm, the increase of the volume plasmon energy is proportional to the inverse square of the nanoparticle diameter, confirming the semimetal to semiconductor transition in Bi nanoparticles.

  6. 低分子量壳聚糖及其衍生物与金属离子配合物研究%Coordination Compounds of Metal Ions with Low-molecular Weight Chitosan and Their Derivative

    Institute of Scientific and Technical Information of China (English)

    丁德润

    2005-01-01

    Chitosan(CTS) of molecular weight 3 × 106 was degraded by oxidation with H2O2. The molecular weight of degraded chitosan (CTS′) was between 5 500-6 000. Through the reaction of degraded chitosan with glyoxylic acid and sodium borohydride, the modified derivative of N-Carboxymethyl degraded chitosan (NCTS′) was obtained. The metal ions of Fe(Ⅱ), Ni(Ⅱ), Cu(Ⅱ) and Cr(Ⅲ) were coordinated at different conditions by degraded chitosan(CTS′→ M(Ⅱ)) and its derivative (NCTS′→ M(Ⅱ))). These coordination compounds were characterized with UV and IR spectroscopy.

  7. Chemically Synthesised Pt Particles on Surface Oxidized Carbon Nanotubes as an Effective Catalyst for Direct Methanol Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    Mohammad; yari; Sajjad; Sadaghat; Sharehjini

    2007-01-01

    1 Results The synthesis, physical characterization and electrochemical analysis of Pt particles prepared using the surface oxidized carbon nanotubes prepared by chemically anchoring Pt onto the surface of the CNTs with 2.0 mol/L HNO3 by refluxing for 10 h to introduce surface functional groups.The particles of Pt are synthesized by reduction with sodium borohydride of H2PtCl6. The electro-oxidation of liquid methanol of this catalyst as a thin layer on glassy carbon electrode is investigated at room te...

  8. Green coconut ( Cocos nucifera Linn) shell extract mediated size controlled green synthesis of polyshaped gold nanoparticles and its application in catalysis

    Science.gov (United States)

    Paul, Koushik; Bag, Braja Gopal; Samanta, Kousik

    2014-08-01

    The shell extract of green coconut ( Cocos nucifera Linn) has been utilized for the synthesis of gold nanoparticles at room temperature under very mild condition without any extra stabilizing or capping agents. The size of the synthesized gold nanoparticles could be controlled by varying the concentration of the shell extract. The stabilized gold nanoparticles were analyzed by surface plasmon resonance spectroscopy, HRTEM, Energy dispersive X-ray spectroscopy and X-ray diffraction studies. The catalytic activity of the freshly synthesized gold nanoparticles was studied for the sodium borohydride reduction of 4-nitrophenol and the kinetics of the reduction reaction were studied spectrophotometrically.

  9. Size control in the synthesis of 1-6 nm gold nanoparticles using folic acid-chitosan conjugate as a stabilizer

    Science.gov (United States)

    Liu, Lili; Zhang, Xianwen; Chaudhuri, Jharna

    2014-09-01

    We report a simple and practical method for the preparation of folic acid (FA)-chitosan functionalized gold nanoparticles (AuNPs) with a very small size (1-6 nm). Sodium borohydride was used as a reducing agent. The size of the AuNPs was controlled by adjusting the mass fraction of FA-chitosan conjugate to Au. The AuNPs were characterized using UV-vis spectroscopy and transmission electron microscopy (TEM). The results indicated that the size distribution of AuNPs decreased ranging from 6 nm to 1 nm with increasing the fraction of FA-chitosan conjugate in the reaction systems.

  10. Feasibility study of the determination of selenium in mineral water by ICPOES using NOVA-2 dual-flow ultrasonic nebulizer and direct hydride generation

    International Nuclear Information System (INIS)

    Full text: A new hydride generator has been explored for the introduction of the sample into ICPOES with radial viewing. The acidic sample and the borohydride solution are delivered by the dual-flow system of a commercial NOVA-2 ultrasonic nebulizer and mixed in the spray chamber. The analytical figures of merit for the determination of As, Sb and Se were evaluated. Results showed that the analytical performance of the new system was superior to that of conventional nebulization systems, including the susceptibility to non-spectroscopic interferences produced by transition metals. The utility of the system was demonstrated in the determination of Se in mineral water. (author)

  11. Ultra-Thin Films of Poly(acrylic acid)/Silver Nanocomposite Coatings for Antimicrobial Applications

    OpenAIRE

    Alaa Fahmy; Eisa, Wael H.; Mohamed Yosef; Ali Hassan

    2016-01-01

    In this work not only colloids of poly(acrylic acid) (PAA) embedded with silver nanoparticles (Ag-NPs) but thin films (10 nm) also were deposited using electrospray deposition technique (ESD). A mixture of sodium borohydride (NaBH4) and ascorbic acid (AA) were utilized to reduce the silver ions to generate Ag-NPs in the PAA matrix. Moreover, sodium tricitrate was used to stabilize the prepared colloids. The obtained colloids and films were characterized using UV-visible, transmission electron...

  12. Destruction of TCE Using Oxidative and Reductive Pathways as Potential In-Situ Treatments for the Contaminated Paducah Groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, S; Li, Y; Xu, J; Tee, Y; Lynch, Andrew

    2007-05-01

    When considering reductive technologies for ground water remediation, it is important to understand the underlying principles that govern kinetics of zero-valent metal dechlorination. Studies involving the use of nanoscale metals (characteristic length <100nm) for chloro-organic degradation have increased reaction rates by 1-2 orders of magnitude with minimal intermediate formation. Typically, these metals are synthesized using modifications of the aqueous phase reduction of metal ions using sodium borohydride presented by Glavee and coworkers. The use of a bimetallic system increases the reactivity of the particle surface by incorporating a second metal that can typically act as a hydrogenation promotor.

  13. Solid hydrides as hydrogen storage reservoirs; Hidruros solidos como acumuladores de hidrogeno

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, A.; Sanchez, C.; Friedrichs, O.; Ares, J. R.; Leardini, F.; Bodega, J.; Fernandez, J. F.

    2010-07-01

    Metal hydrides as hydrogen storage materials are briefly reviewed in this paper. Fundamental properties of metal-hydrogen (gas) system such as Pressure-Composition-Temperature (P-C-T) characteristics are discussed on the light of the metal-hydride thermodynamics. Attention is specially paid to light metal hydrides which might have application in the car and transport sector. The pros and cons of MgH{sub 2} as a light material are outlined. Researches in course oriented to improve the behaviour of MgH{sub 2} are presented. Finally, other very promising alternative materials such as Al compounds (alanates) or borohydrides as light hydrogen accumulators are also considered. (Author)

  14. Structural Characterization and Mechanical Properties of As-plated and Heat Treated Electroless Ni-B-P Alloy Coatings

    OpenAIRE

    P. G. Venkatakrishnan; S. S. Mohamed Nazirudeen; T.S.N. Sankara Narayanan

    2014-01-01

    The Ni-B-P alloy coatings were made autocatalytically (electroless) using an alkaline plating bath with nickel chloride hexahydrate (NiCl2.6H2O) as the source of nickel ions, sodium borohydride (NaBH4) and sodium hypophosphite (NaH2PO2) as reducing agents and source of boron and phosphorous ions, respectively. The effects of bath concentrations on the plating rate, composition of coating, surface morphology, structural features and microhardness have been studied by varying NaBH4 concentra...

  15. Electroless Ni-B-W coatings for improving hardness, wear and corrosion resistance: Nanašanje Ni-B-W s cementacijskim galvaniziranjem za izboljšavo trdote, obrabe in odpornosti proti koroziji:

    OpenAIRE

    Aydeniz, Ali Imre; Calli, Cagdas; Dil, Gökce; Göksenli, Ali; MUHAFFEL, Faiz; Yüksel, Behiye

    2013-01-01

    In this study the formation of a Ni-B-W coating on steel using an electroless plating process and evaluation of the hardness, wear and corrosion resistance was analyzed. The Ni-B-W coating was prepared using an alkaline borohydride-reduced electroless nickel bath. Scanning electron microscopy (SEM) of the cross-sectional view of the Ni-B-W coating was analyzed and the layer characteristics were investigated. The Ni-B-W coating was characterized using XRD. The study reveals that the Ni-B-W coa...

  16. Determination of Trace Germanium in Marine Sediments by Hydride Generation-Atomic Fluorescence Spectrometry (HG-AFS)

    Institute of Scientific and Technical Information of China (English)

    LI Jing; ZHAO Shilan; ZHANG Zhaohui; ZENG Xianjie

    2004-01-01

    A method for the analysis of trace germanium in marine sediments by HG-AFS has been investigated. The experimental conditions such as the acidity of reduction reaction, the amount of sodium boro-hydride, the carrier gas flow rate, etc., were tested and optimized by using a kind of orthogonal design. The detection limit of the presented method is 0.95 μg L-1 for germanium. The calibration curve shows a satisfactory line in the concentration range 0-320 μg L-1 Ge with a variation coefficient of ±2.1%.

  17. Cob(I)alamin Reacts with Sucralose to Afford an Alkylcobalamin : Relevance to In Vivo Cobalamin and Sucralose Interaction

    OpenAIRE

    Motwani V, Hitesh; Qiu, Shiran; Golding, Bernard T.; Kylin, Henrik; Törnqvist, Margareta

    2011-01-01

    Vitamin B12, viz., cyano- or hydroxo-cobalamin, can be chemically or enzymatically converted into the derivatives methyl- and adenosyl-cobalamin, which are complex organometallic cofactors associated with several cobalamin-dependent enzymes. The reduced form of vitamin B12, cob(I)alamin {Cbl(I)}, obtained by reduction of hydroxocobalamin (OH-Cbl) with e.g. sodium borohydride, is one of the most powerful nucleophiles known. Cbl(I) was shown to react readily with the synthetic sweetener sucralo...

  18. Synthesis and Characterization of Nanostructured Fe-Ni Alloy Whisker

    Institute of Scientific and Technical Information of China (English)

    DONG Guo-jun; WANG Gui-xiang; ZHANG Mi-lin; LI Ru-Min; WANG Jun

    2002-01-01

    The nanocrystalline γ-(Fe,Ni) alloy whiskers have been prepared by chemical reduction of Fe2+ and Ni2+ ions with potassium borohydride under the function of a dispersant agent PE followed by heat treatment at 600℃ under the protection of nitrogen.Conditions, such as quantity of NaOH, concentration of salts, and species of surfactants, of preparation of Fe-Ni alloy have been discussed. X-ray diffraction(XRD), transmission electron microscopy(TEM) and vibrating sample magnetometer(VSM) characterized the synthesized Fe-Ni alloy. Character, capability and use of the materials have been summarized.

  19. Synthesis of a sucrose dimer with enone tether; a study on its functionalization

    Directory of Open Access Journals (Sweden)

    Zbigniew Pakulski

    2014-05-01

    Full Text Available The reaction of appropriately functionalized sucrose phosphonate with sucrose aldehyde afforded a dimer composed of two sucrose units connected via their C6-positions (‘the glucose ends’. The carbonyl group in this product (enone was stereoselectively reduced with zinc borohydride and the double bond (after protection of the allylic alcohol formed after reduction was oxidized with osmium tetroxide to a diol. Absolute configurations of the allylic alcohol as well as the diol were determined by circular dichroism (CD spectroscopy using the in situ dimolybdenum methodology.

  20. On the chemistry of Ingenol. Pt. 5. Preparation of tritium-labeled 3-O-tetradecanoylingenol ([2O-[sup 3]H]-3-TI)

    Energy Technology Data Exchange (ETDEWEB)

    Roeser, H.; Sorg, B.; Hecker, E. (Inst. of Biochemistry, Deutsches Krebsforschungszentrum, Heidelberg (Germany))

    1992-07-01

    Tritium-labeling of the ingenol monoester 3-O-tetradecanoylingenol (3-TI), the prototype tumor promoter of the ingenane type diterpene esters, is described. The preparation starts with oxidation of 3-TI by manganese dioxide to yield 3-TI-20-aldehyde which is reduced by [[sup 3]H]-sodium borohydride in the presence of equimolar amounts of cerium trichloride hexahydrate to give [20-[sup 3]H]-3-TI. The labeled promoter is obtained in 42% overall yield with a specific radioactivity of 15.8 Ci/mmol. (orig.).

  1. New Synthesis of Pt-Ru Nanoparticles on Surface Modified Carbon Vulcane XC-72 as an Effective Catalyst for Direct Methanol Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    Ahmad; Nozad; Golikand; Sajjad; Sadaghat; Sharehjini; Mohammad; Yari

    2007-01-01

    1 Results Pt-Ru nanoparticles are synthesised on the surface oxidized carbon Vulcane XC-72 as catalyst support by chemically anchoring Pt and Ru onto the surface of modified carbon vulcane XC-72 (by refluxing in 70% HNO3 at 120 ℃ for 12 h to introduce surface functional groups) .The nanoparticles of Pt and Ru are synthesized by reduction of H2PtCl6 and K4Ru(CN)6 with sodium borohydride in a 5.5 buffer solution of sodium citrate,the complexation of citrate with metal ions is beneficial to the formati...

  2. Platinium Nanoparticles Deposited on Oxygen-Containing Functional Groups at Carbon Vulcane XC-72 as a Cathode Catalyst for Direct Methanol Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    Sajjad; Sadaghat; Sharehjini; Ahmad; Nozad; Golikand; Mohammad; Yari

    2007-01-01

    1 Results Surface oxidized carbon vulcane XC-72 as catalyst support, prepared by chemically anchoring Pt onto the surface modified carbon vulcane XC-72. The nanoparticles of Pt are synthesized by reduction of H2PtCl6 with sodium borohydride in a 5.5 buffer solution of sodium citrate, the complexation of citrate with metal ions is beneficial to the formation of nanoparticles. For comparison, an electrode is prepared by E-Tek Pt/C 20 Wt% with a typical Pt loading of 50 μg·cm-2, that shows higher specifi...

  3. Highly dispersed Pd nanoparticles on chemically modified graphene with aminophenyl groups for formic acid oxidation

    Institute of Scientific and Technical Information of China (English)

    Yang Su-Dong; Shen Cheng-Min; Tong Hao; He Wei; Zhang Xiao-Gang; Gao Hong-Jun

    2011-01-01

    A novel electrode material based on chemically modified graphene (CMG) with aminophenyl groups is covalently functionalized by a nucleophilic ring-opening reaction between the epoxy groups of graphene oxide and the aminophenyl groups of p-phenylenediamine.Palladium nanoparticles with an average diameter of 4.2 nm are deposited on the CMG by a liquid-phase borohydride reduction.The electrocatalytic activity and stability of the Pd/CMG composite towards formic acid oxidation are found to be higher than those of reduced graphene oxide and commercial carbon materials such as Vulcan XC-72 supported Pd electrocatalysts.

  4. Effects of the addition of an organic polymer on the hydrolysis of sodium tetrahydroborate in batch reactors

    OpenAIRE

    M. J. F. Ferreira; Fernandes, V. R.; Gales, L.; Rangel, C. M.; Pinto, A. M. F. R.

    2010-01-01

    An experimental study is presented both on the generation and storage of molecular hydrogen (H2) by small additions of an organic polymer - carboxymethyl cellulose (CMC) - to sodium borohydride (NaBH4) through the alkaline hydrolysis, in the presence of a powdered nickel-ruthenium based catalyst reused from 274 to 282 times. The experiments were performed at 45 °C in two batch reactors with internal volumes of 0.229 L and 0.369 L, made of stainless-steel with bottom conical shape, positioned ...

  5. Development of novel catalytically active polymer-metal-nanocomposites based on activated foams and textile fibers

    Science.gov (United States)

    Domènech, Berta; Ziegler, Kharla K.; Carrillo, Fernando; Muñoz, Maria; Muraviev, Dimitri N.; Macanás, Jorge

    2013-05-01

    In this paper, we report the intermatrix synthesis of Ag nanoparticles in different polymeric matrices such as polyurethane foams and polyacrylonitrile or polyamide fibers. To apply this technique, the polymer must bear functional groups able to bind and retain the nanoparticle ion precursors while ions should diffuse through the matrix. Taking into account the nature of some of the chosen matrices, it was essential to try to activate the support material to obtain an acceptable value of ion exchange capacity. To evaluate the catalytic activity of the developed nanocomposites, a model catalytic reaction was carried out in batch experiments: the reduction of p-nitrophenol by sodium borohydride.

  6. MAGNETIC POLYMER MICROSPHERE STABILIZED GOLD NANOCOLLOIDS AS A FACILELY RECOVERABLE CATALYST

    Institute of Scientific and Technical Information of China (English)

    Han Zhang; Xin-lin Yang

    2011-01-01

    Magnetically responsive hierarchical magnetite/silica/poly(ethyleneglycol dimethacrylate-co-4-vinylpyridine) (Fe3O4/SiO2/P(EGDMA-co-VPy)) tri-layer microspheres were used as stabilizers for gold metallic nanocolloids as a facilely recoverable catalyst with the reduction of 4-nitrophenol to 4-aminophenol as a model reaction. The magnetic microsphere stabilized gold metallic nanocolloids were prepared by in situ reduction of gold chloride trihydrate with borohydride as reductant via the stabilization effect of the pyridyl groups to gold nanoparticles on the surface of the outer shell-layer of the inorganic/polymer fri-layer microspheres.

  7. Study of Lewis Acid Promoting KBH_4 Reduce Carboxylic Acid Ester%Lewis酸促进KBH_4还原某些羧酸酯的研究

    Institute of Scientific and Technical Information of China (English)

    汪一波; 金召磊; 唐守万; 孙佰申; 潘富友; 高建荣

    2011-01-01

    Potassium borohydride reduction of some carboxylic esters into the corresponding alcohols by the Lewis acid was introduced.The structures were confirmed by 1HNMR,MS and IR,consistent with its structure and the target,and the yield of 37.5~68.5.%在Lewis酸的作用下,研究硼氢化钾将某些羧酸酯还原成相应的醇。其产物经1HNMR、MS和IR表征,其结构与目标物一致,收率在37.5~68.5之间。

  8. Facile synthesis and regeneration of Mg(BH4)2 by high energy reactive ball milling of MgB2.

    Science.gov (United States)

    Gupta, Shalabh; Hlova, Ihor Z; Kobayashi, Takeshi; Denys, Roman V; Chen, Fu; Zavaliy, Ihor Y; Pruski, Marek; Pecharsky, Vitalij K

    2013-01-28

    We report direct hydrogenation of MgB(2) in a planetary ball mill. Magnesium borohydride, Mg(BH(4))(2), and various polyhedral borane anion salts have been synthesized at pressures between 50 and 350 bar H(2) without the need for subsequent isothermal hydrogenation at elevated temperature and pressure. The obtained products release ∼4 wt% H(2) below 390 °C, and a major portion of Mg(BH(4))(2) transforms back to MgB(2) at around 300 °C, demonstrating the possibility of reversible hydrogen storage in an Mg(BH(4))(2)-MgB(2) system.

  9. Morphology Analysis of Nickel-boron/ diamond Electroless Deposition

    Institute of Scientific and Technical Information of China (English)

    WANG Lin; ZHU Xuanmin; ZHOU Jian; OUYANG Shixi

    2008-01-01

    The influences of mass concentration of nickel chloride hexahydrate, sodium borohydride,ethylenediamine, pH value, bath temperature on deposition rate were studied with orthogonal experiments by a series of pre-treatments on micro-diamond particle, and the optimized parameters were obtained. Both the morphology and the composition of original diamond and the diamond with Ni-B coating were analyzed by SEM and XRD respectively. The SEM image shows that the spherical Ni-B particle is coated upon diamond.XRD pattern shows that the coating compositions are Ni and Ni2B.

  10. Preparation of Silver Nanostructures from Bicontinuous Microemulsions

    OpenAIRE

    Pedroza-Toscano, M. A.; Rabelero-Velasco, M.; Díaz de León, R.; H. Saade; R. G. López; E. Mendizábal; Puig, J. E.

    2012-01-01

    Precipitation of silver nanoparticles at 70°C was carried out by dosing a 1.3 M sodium borohydride aqueous solution over bicontinuous microemulsions formed with a mixture of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) and sodium dodecylsulfate (SDS) as surfactants, a 0.5 M silver nitrate aqueous solution, and toluene. Weight ratios of 2.5/1 and 3/1 AOT/SDS were used in the precipitation reactions. Silver nanoparticles were characterized by transmission electronic microscopy, X-ray diffracti...

  11. Visual and colorimetric detection of mercury(II) ion using gold nanoparticles stabilized with a dithia-diaza ligand

    International Nuclear Information System (INIS)

    We have developed a simple method for the highly selective colorimetric detection of dissolved mercury(II) ions via direct formation of gold nanoparticles (AuNPs). The dithia-diaza ligand 2-[3-(2-amino-ethylsulfanyl)-propylsulfanyl]-ethylamine (AEPE) was used as a stabilizer to protect AuNPs from aggregation and to impart highly selective recognition of Hg(II) ion over other metal ions. A solution of Au(III) ion is directly reduced by sodium borohydride in the presence of AEPE and the detergent Triton X-100. This results in the formation of AEPE-AuNPs and a red coloration of the solution. On the other hand, in the presence of Hg(II), the solution turns blue within a few seconds after the addition of borohydride. This can be detected spectrophotometrically or even visually. The method was successfully applied to quantify Hg(II) levels in water sample, with a minimum detectable concentration as low as 35 nM. (author)

  12. Study on Hydrogen Storage Materials

    Science.gov (United States)

    Sugiyama, Jun

    2016-09-01

    Complex hydrides have been heavily investigated as a hydrogen storage material, particularly for future vehicular applications. The present major problem of such complex hydrides is their relatively high hydrogen desorption temperature (Td). In order to find a predominant parameter for determining Td, we have investigated internal nuclear magnetic fields in several complex hydrides, such as, lithium and sodium alanates, borohydrides, and magnesium hydrides, with a muon spin rotation and relaxation (μ+SR) technique. At low temperatures, the μ+SR spectrum obtained in a zero external field (ZF) exhibits a clear oscillation due to the formation of a three spin 1/2 system, HμH, besides Mg(BH4)2 and Sc(BH4)2. Such oscillatory signal becomes weaker and weaker with increasing temperature, and finally disappears above around room temperature. However, the volume fraction of the HμH signal to the whole asymmetry at 5 K is found to be a good indicator for Td in borohydrides. At high temperatures, on the contrary, the ZF-spectrum for MgH2 shows a Kubo-Toyabe like relaxation due to a random nuclear magnetic field of 1H. Such nuclear magnetic field becomes dynamic well below Td in the milled MgH2, indicating a significant role on H-diffusion in solids for determining Td.

  13. Enhanced photoproduction of hydrogen peroxide by humic substances in the presence of phenol electron donors.

    Science.gov (United States)

    Zhang, Yi; Simon, Kelli A; Andrew, Andrea A; Del Vecchio, Rossana; Blough, Neil V

    2014-11-01

    Addition of a series of phenol electron donors to solutions of humic substances (HS) enhanced substantially the initial rates of hydrogen peroxide (H2O2) photoproduction (RH2O2), with enhancement factors (EF) ranging from a low of ∼3 for 2,4,6-trimethylphenol (TMP) to a high of ∼15 for 3,4-dimethoxyphenol (DMOP). The substantial inhibition of the enhanced RH2O2 following borohydride reduction of the HS, as well as the dependence of RH2O2 on phenol and dioxygen concentrations are consistent with a mechanism in which the phenols react with the triplet excited states of (aromatic) ketones within the HS to form initially a phenoxy and ketyl radical. The ketyl radical then reacts rapidly with dioxygen to regenerate the ketone and form superoxide (O2-), which subsequently dismutates to H2O2. However, as was previously noted for the photosensitized loss of TMP, the incomplete inhibition of the enhanced RH2O2 following borohydride reduction suggests that there may remain another pool of oxidizing triplets. The results demonstrate that H2O2 can be generated through an additional pathway in the presence of sufficiently high concentrations of appropriate electron donors through reaction with the excited triplet states of aromatic ketones and possibly of other species such as quinones. However, in some cases, the much lower ratio of H2O2 produced to phenol consumed suggests that secondary reactions could alter this ratio significantly.

  14. Synthesis of N-(4-pyridyl[14C]carbonylamino)-1,2,[3H]3,6-tetrahydropyridine and the mono-labelled [14C]- and [3H]-analogues

    International Nuclear Information System (INIS)

    Reaction of isonicotinic [14C] acid hydrazide with the Zinke salt afforded N-(4-pyridyl [14C] carbonylimino)pyridinium yield (A) in 81% chemical yield. Sodium borohydride reduction of (A) gave N-(4-pyridyl [14C] carbonylamino)-1,2,3,6-tetrahydropyridine in 60% chemical yield with a specific activity of 6.17 mCi mM-1. Alternatively reduction of N-(4-pyridylcarbonylimino) pyridinium yield using absolute ethanol and [3H]-water as solvent yielded N-(4-pyridylcarbonylamino)-1,2,[3H]3,6-tetrahydropyridine in 52.6% chemical yield with a specific activity of 1.14 mCi mM-1. N-(4-Pyridyl[14C]carbonylamino-1,2,[3H]3,6-tetrahydropyridine was similarly prepared by sodium borohydride reduction of (A) using absolute ethanol and [3H]-water as solvent in 46% chemical yield with specific activities of 1.31 and 5.66 mCi mM-1 respectively for [3H] and [14C]. (author)

  15. Neomycin fixation followed by ethanol pretreatment leads to reduced buckling and inhibition of calcification in bioprosthetic valves.

    Science.gov (United States)

    Raghavan, Devanathan; Shah, Sagar R; Vyavahare, Naren R

    2010-01-01

    Glutaraldehyde crosslinked bioprosthetic heart valves (BHVs) have two modalities of failure: degeneration (cuspal tear due to matrix failure) and calcification. They can occur independently as well as one can lead to the other causing co-existence. Calcific failure has been extensively studied before and several anti-calcification treatments have been developed; however, little research is directed to understand mechanisms of valvular degeneration. One of the shortcomings of glutaraldehyde fixation is its inability to stabilize all extracellular matrix components in the tissue. Previous studies from our lab have demonstrated that neomycin could be used as a fixative to stabilize glycosaminoglycans (GAGs) present in the valve to improve matrix properties. But neomycin fixation did not prevent cuspal calcification. In the present study, we wanted to enhance the anti-calcification potential of neomycin fixed valves by pre-treating with ethanol or removing the free aldehydes by sodium borohydride treatment. Ethanol treatment has been previously used and found to have excellent anti-calcification properties for valve cusps. Results demonstrated in this study suggest that neomycin followed by ethanol treatment effectively preserves GAGs both in vitro as well as in vivo after subdermal implantation in rats. In vivo calcification was inhibited in neomycin fixed cusps pretreated with ethanol compared to glutaraldehyde (GLUT) control. Sodium borohydride treatment by itself did not inhibit calcification nor stabilized GAGs against enzymatic degradation. Neomycin fixation followed by ethanol treatment of BHVs could prevent both modalities of failure, thereby increasing the effective durability and lifetime of these bioprostheses several fold.

  16. Scalable synthesis of Cu-based ultrathin nanowire networks and their electrocatalytic properties

    Science.gov (United States)

    Hong, Wei; Wang, Jin; Wang, Erkang

    2016-02-01

    In this research, we developed an easy way to generate CuM (M = Pd, Pt and PdPt) ultrathin nanowire networks by simply injecting the metallic precursors into an aqueous solution which contained sodium borohydride under vigorous stirring. The reaction can be finished quickly without needing any other reagents, thus leaving the products with a clean surface. The prepared materials show an ultrathin diameter of less than 5 nanometers. The reaction can be easily amplified, resulting in scalable products. These properties combined with the superior catalytic performance of the prepared CuM nanowire networks underpin their potential use in glycerol electrooxidation reaction.In this research, we developed an easy way to generate CuM (M = Pd, Pt and PdPt) ultrathin nanowire networks by simply injecting the metallic precursors into an aqueous solution which contained sodium borohydride under vigorous stirring. The reaction can be finished quickly without needing any other reagents, thus leaving the products with a clean surface. The prepared materials show an ultrathin diameter of less than 5 nanometers. The reaction can be easily amplified, resulting in scalable products. These properties combined with the superior catalytic performance of the prepared CuM nanowire networks underpin their potential use in glycerol electrooxidation reaction. Electronic supplementary information (ESI) available: Experimental details, additional TEM, XPS and electrochemical characterizations. See DOI: 10.1039/c5nr07516e

  17. Topo-optical reactions for the identification of O-acyl sugars in amyloid deposits.

    Science.gov (United States)

    Richter, Susann; Makovitzky, Josef

    2009-01-01

    The aldehyde bisulfite toluidine blue (ABT) reaction with former saponification (KOH-ABT) and periodic acid-borohydride reduction-saponification (PB-KOH-ABT) were applied to sections of human amyloid deposits in the respiratory tract. The saponification-induced increase in ABT-reactivity was confined to the presence of O-acyl sugars associated with the amyloid fibrils. The anisotropic and metachromatic effect in the ABT and KOH-ABT reaction was reduced in the corresponding PB-KOH-ABT reaction, a difference attributed to the removal of staining due to neutral carbohydrate residues. Since the periodic acid-borohydride reduction abolishes all pre-existing ABT-reactivity of neutral sugar vicinal diols, the isolated KOH-effect could be shown using the PB-KOH-ABT reaction. By application of this sequence, the problem identifying small quantities of O-acyl sugars was solved. It is suggested that the KOH-effect depends upon the removal of O-acyl substituents located on the polyhydroxy side chain (C7, C8, C9) of sialic acid residues. An advantage of such topo-optical reactions over biochemical techniques is the exact localization of O-acyl sugars in tissue sites. By means of the KOH-ABT and PB-KOH-ABT reactions we have demonstrated, for the first time, that O-acyl sugars occur within amyloid deposits.

  18. FUNDAMENTAL ENVIRONMENTAL REACTIVITY TESTING AND ANALYSIS OF THE HYDROGEN STORAGE MATERIAL 2LIBH4 MGH2

    Energy Technology Data Exchange (ETDEWEB)

    James, C.; Anton, D.; Cortes-Concepcion, J.; Brinkman, K.; Gray, J.

    2012-01-10

    While the storage of hydrogen for portable and stationary applications is regarded as critical in bringing PEM fuel cells to commercial acceptance, little is known of the environmental exposure risks posed in utilizing condensed phase chemical storage options as in complex hydrides. It is thus important to understand the effect of environmental exposure of metal hydrides in the case of accident scenarios. Simulated tests were performed following the United Nations standards to test for flammability and water reactivity in air for a destabilized lithium borohydride and magnesium hydride system in a 2 to 1 molar ratio respectively. It was determined that the mixture acted similarly to the parent, lithium borohydride, but at slower rate of reaction seen in magnesium hydride. To quantify environmental exposure kinetics, isothermal calorimetry was utilized to measure the enthalpy of reaction as a function of exposure time to dry and humid air, and liquid water. The reaction with liquid water was found to increase the heat flow significantly during exposure compared to exposure in dry or humid air environments. Calorimetric results showed the maximum normalized heat flow the fully charged material was 6 mW/mg under liquid phase hydrolysis; and 14 mW/mg for the fully discharged material also occurring under liquid phase hydrolysis conditions.

  19. Electrochemical hydrogen Storage Systems

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Digby Macdonald

    2010-08-09

    As the global need for energy increases, scientists and engineers have found a possible solution by using hydrogen to power our world. Although hydrogen can be combusted as a fuel, it is considered an energy carrier for use in fuel cells wherein it is consumed (oxidized) without the production of greenhouse gases and produces electrical energy with high efficiency. Chemical storage of hydrogen involves release of hydrogen in a controlled manner from materials in which the hydrogen is covalently bound. Sodium borohydride and aminoborane are two materials given consideration as chemical hydrogen storage materials by the US Department of Energy. A very significant barrier to adoption of these materials as hydrogen carriers is their regeneration from 'spent fuel,' i.e., the material remaining after discharge of hydrogen. The U.S. Department of Energy (DOE) formed a Center of Excellence for Chemical Hydrogen Storage, and this work stems from that project. The DOE has identified boron hydrides as being the main compounds of interest as hydrogen storage materials. The various boron hydrides are then oxidized to release their hydrogen, thereby forming a 'spent fuel' in the form of a lower boron hydride or even a boron oxide. The ultimate goal of this project is to take the oxidized boron hydrides as the spent fuel and hydrogenate them back to their original form so they can be used again as a fuel. Thus this research is essentially a boron hydride recycling project. In this report, research directed at regeneration of sodium borohydride and aminoborane is described. For sodium borohydride, electrochemical reduction of boric acid and sodium metaborate (representing spent fuel) in alkaline, aqueous solution has been investigated. Similarly to literature reports (primarily patents), a variety of cathode materials were tried in these experiments. Additionally, approaches directed at overcoming electrostatic repulsion of borate anion from the cathode, not

  20. The removal of uranium onto carbon-supported nanoscale zero-valent iron particles

    Energy Technology Data Exchange (ETDEWEB)

    Crane, Richard A., E-mail: richardandrewcrane@gmail.com; Scott, Thomas [University of Bristol, School of Physics, Interface Analysis Centre (United Kingdom)

    2014-12-15

    In the current work carbon-supported nanoscale zero-valent iron particles (CS nZVI), synthesised by the vacuum heat treatment of ferric citrate trihydrate absorbed onto carbon black, have been tested for the removal of uranium (U) from natural and synthetic waters. Two types of CS nZVI were tested, one vacuum annealed at 600 °C for 4 h and the other vacuum annealed at 700 °C for 4 h, with their U removal behaviour compared to nZVI synthesised via the reduction of ferrous iron using sodium borohydride. The batch systems were analysed over a 28-day reaction period during which the liquid and nanoparticulate solids were periodically analysed to determine chemical evolution of the solutions and particulates. Results demonstrate a well-defined difference between the two types of CS nZVI, with greater U removal exhibited by the nanomaterial synthesised at 700 °C. The mechanism has been attributed to the CS nZVI synthesised at 700 °C exhibiting (i) a greater proportion of surface oxide Fe{sup 2+} to Fe{sup 3+} (0.34 compared to 0.28); (ii) a greater conversion of ferric citrate trihydrate [2Fe(C{sub 6}H{sub 5}O{sub 7})·H{sub 2}O] to Fe{sup 0}; and (iii) a larger surface area (108.67 compared to 88.61 m{sup 2} g{sup −1}). Lower maximum U uptake was recorded for both types of CS nZVI in comparison with the borohydride-reduced nZVI. A lower decrease in solution Eh and DO was also recorded, indicating that less chemical reduction of U was achieved by the CS nZVI. Despite this, lower U desorption in the latter stages of the experiment (>7 days) was recorded for the CS nZVI synthesised at 700 °C, indicating that carbon black in the CS nZVI is likely to have contributed towards U sorption and retention. Overall, it can be stated that the borohydride-reduced nZVI were significantly more effective than CS nZVI for U removal over relatively short timescales (e.g. <48 h), however, they were more susceptible to U desorption over extended time periods.

  1. Camphor-mediated synthesis of carbon nanoparticles, graphitic shell encapsulated carbon nanocubes and carbon dots for bioimaging.

    Science.gov (United States)

    Oza, Goldie; Ravichandran, M; Merupo, Victor-Ishrayelu; Shinde, Sachin; Mewada, Ashmi; Ramirez, Jose Tapia; Velumani, S; Sharon, Madhuri; Sharon, Maheshwar

    2016-01-01

    A green method for an efficient synthesis of water-soluble carbon nanoparticles (CNPs), graphitic shell encapsulated carbon nanocubes (CNCs), Carbon dots (CDs) using Camphor (Cinnamomum camphora) is demonstrated. Here, we describe a competent molecular fusion and fission route for step-wise synthesis of CDs. Camphor on acidification and carbonization forms CNPs, which on alkaline hydrolysis form CNCs that are encapsulated by thick graphitic layers and on further reduction by sodium borohydride yielded CDs. Though excitation wavelength dependent photoluminescence is observed in all the three carbon nanostructures, CDs possess enhanced photoluminescent properties due to more defective carbonaceous structures. The surface hydroxyl and carboxyl functional groups make them water soluble in nature. They possess excellent photostability, higher quantum yield, increased absorption, decreased cytotoxicity and hence can be utilized as a proficient bio imaging agent. PMID:26905737

  2. Reductive amination of aldehydes and ketones mediated by sodium malonyloxyborohydride%丙二酰氧基硼氢化钠介入的醛、酮还原胺化反应

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    叙述了在原位生成的丙二酰氧基硼氢化钠存在下的醛、酮还原胺化反应。讨论了还原胺化的反应条件和立体位阻效应,发现丙二酰氧基硼氢化钠是一个高选择性还原剂,在给定条件下不发生自身还原反应。%The reductive amination of aldehydes and ketones with amines in the presence of sodium malonyloxyborohydride 1 prepared in situ from malonic acid and sodium borohydride in anhydrous THF is described. The reaction conditions and the steric hindrance effect for the reducrive amination are also discussed. It was found that self-reduction of 1 did not occur onder the experimental conditions.

  3. Synthesis, characterization and vibrational spectroscopic studies of different particle size of gold nanoparticle capped with polyvinylpyrrolidone

    Energy Technology Data Exchange (ETDEWEB)

    Seoudi, R., E-mail: rsmawed@yahoo.co [Spectroscopy Department, Physics Division, National Research Center, Dokki, Cairo 12622 (Egypt); Fouda, A.A. [Spectroscopy Department, Physics Division, National Research Center, Dokki, Cairo 12622 (Egypt); Elmenshawy, D.A. [Physics Department, Faculty of Women, Ain Shams University, Cairo (Egypt)

    2010-02-01

    Different sizes of gold nanoparticle (AuNPs) were prepared by UV irradiation technique. Polyvinylpyrrolidone (PVP) used as a stabilizing agent, and reducing agent was sodium borohydride. The main particle size was calculated from TEM images and the particle size was depending on the wavelength and time of UV irradiation. The FTIR data obtained that the band position of C=O and C-N of pyrrolidone ring was shifted as a result of donor-acceptor interactions between these groups with AuNPs surface. The origin of the surface plasmon resonance (SPR) was explored from UV-VIS spectroscopy. The surface plasmon resonance (SPR) band position was explained in terms of the size of AuNPs. The results were confirmed that SP resonance was depending on the particle sizes that depend on the wavelength and time of UV irradiation.

  4. Synthesis, characterization, biodistribution and scintigraphy of 99mTc-paclitaxel. A potential tracer of paclitaxel

    International Nuclear Information System (INIS)

    99mTc-paclitaxel was synthesized by using sodium borohydride as a reducing agent. Greater than 95 % labelling efficiency was achieved. Radiochemical purity of the synthesized 99mTc-paclitaxel was validated by thin layer chromatography (TLC) scanner and high performance liquid chromatography (HPLC). 99mTc-paclitaxel passed in vitro stability tests. Biodistribution and scintigraphy studies were performed in Sprague-Dawley rats. The biodistribution study results of 99mTc-paclitaxel were related mainly to the metabolism and excretion routes followed by the parental drug, paclitaxel. Apart from that, biodistribution of 99mTc-paclitaxel was altered after pre-treatment with cold paclitaxel. Hence, 99mTc-paclitaxel may be used as a tracer for paclitaxel. (author)

  5. EFFECT OF PRETREATMENT ON PT-CO/C CATHODE CATALYSTS FOR THE OXYGEN-REDUCTION REACTION

    Energy Technology Data Exchange (ETDEWEB)

    Fox, E.; Colon-Mercado, H.

    2010-01-19

    Carbon supported Pt and Pt-Co electrocatalysts for the oxygen reduction reaction in low temperature fuel cells were prepared by the reduction of the metal salts with sodium borohydride and sodium formate. The effect of surface treatment with nitric acid on the carbon surface and Co on the surface of carbon prior to the deposition of Pt was studied. The catalysts where Pt was deposited on treated carbon the ORR reaction preceded more through the two electron pathway and favored peroxide production, while the fresh carbon catalysts proceeded more through the four electron pathway to complete the oxygen reduction reaction. NaCOOH reduced Pt/C catalysts showed higher activity that NaBH{sub 4} reduced Pt/C catalysts. It was determined that the Co addition has a higher impact on catalyst activity and active surface area when used with NaBH{sub 4} as reducing agent as compared to NaCOOH.

  6. Method for synthesizing metal bis(borano) hypophosphite complexes

    Science.gov (United States)

    Cordaro, Joseph G.

    2013-06-18

    The present invention describes the synthesis of a family of metal bis(borano) hypophosphite complexes. One procedure described in detail is the syntheses of complexes beginning from phosphorus trichloride and sodium borohydride. Temperature, solvent, concentration, and atmosphere are all critical to ensure product formation. In the case of sodium bis(borano) hypophosphite, hydrogen gas was evolved upon heating at temperatures above 150.degree. C. Included in this family of materials are the salts of the alkali metals Li, Na and K, and those of the alkaline earth metals Mg and Ca. Hydrogen storage materials are possible. In particular the lithium salt, Li[PH.sub.2(BH.sub.3).sub.2], theoretically would contain nearly 12 wt % hydrogen. Analytical data for product characterization and thermal properties are given.

  7. Lantana camara Linn leaf extract mediated green synthesis of gold nanoparticles and study of its catalytic activity

    Science.gov (United States)

    Dash, Shib Shankar; Bag, Braja Gopal; Hota, Poulami

    2015-03-01

    A facile one-step green synthesis of stable gold nanoparticles (AuNPs) has been described using chloroauric acid (HAuCl4) and the leaf extract of Lantana camara Linn (Verbenaceae family) at room temperature. The leaf extract enriched in various types of plant secondary metabolites is highly efficient for the reduction of chloroaurate ions into metallic gold and stabilizes the synthesized AuNPs without any additional stabilizing or capping agents. Detailed characterizations of the synthesized gold nanoparticles were carried out by surface plasmon resonance spectroscopy, transmission electron microscopy, dynamic light scattering, Zeta potential, X-ray diffraction and Fourier transform-infrared spectroscopy studies. The synthesized AuNPs have been utilized as a catalyst for the sodium borohydride reduction of 4-nitrophenol to 4-aminophenol in water at room temperature under mild reaction condition. The kinetics of the reduction reaction has been studied spectrophotometrically.

  8. Synthesis of copper nanocolloids using a continuous flow based microreactor

    Science.gov (United States)

    Xu, Lei; Peng, Jinhui; Srinivasakannan, C.; Chen, Guo; Shen, Amy Q.

    2015-11-01

    The copper (Cu) nanocolloids were prepared by sodium borohydride (NaBH4) reduction of metal salt solutions in a T-shaped microreactor at room temperature. The influence of NaBH4 molar concentrations on copper particle's diameter, morphology, size distribution, and elemental compositions has been investigated by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The ultraviolet-visible spectroscopy (UV-vis) was used to verify the chemical compounds of nanocolloids and estimate the average size of copper nanocolloids. The synthesized copper nanocolloids were uniform in size and non-oxidized. A decrease in the mean diameter of copper nanocolloids was observed with increasing NaBH4 molar concentrations. The maximum mean diameter (4.25 nm) occurred at the CuSO4/NaBH4 molar concentration ratio of 1:2.

  9. A Sensitive Surface-enhanced Raman Scattering Method for Determination of Melamine with Aptamer-modified Nanosilver Probe

    Institute of Scientific and Technical Information of China (English)

    温桂清; 周莲平; 李廷盛; 梁爱惠; 蒋治良

    2012-01-01

    The small nanosilver was prepared by the sodium borohydride procedure. The aptamer was used to modify nanosilver to obtain a nanosilver-aptamer (AgssDNA) SERS probe for the determination of melamine. In pH 6.6 phosphate buffer solution and in the presence of NaCI, the AgssDNA probe specifically combined with melamine to release nanosilver particles that were aggregated to nanosilver clusters, which exhibited SERS effect at 240 cm-1. When melamine concentration increased, the nanosilver clusters increased, and the SERS intensity at 240 cm-1 in- creased. The increased SERS intensity AI240cm, is linear to melamine concentration in the range of 6.3--403.6 μg.L 1, with a detection limit of 1.2 μg L 1. This assay was applied to determination of melamine in milk, with sat- isfactory results. Keywords melamine, apatmer-modified nanosilver, aggregation, surface-enhanced Raman scattering

  10. Thermally Activated Palm Kernel Based Carbon as a Support for Edible Oil Hydrogenation Catalyst

    Directory of Open Access Journals (Sweden)

    Abdulmajid Alshaibani

    2013-01-01

    Full Text Available Activated carbon has distinctive properties as a support for hydrogenation catalysts. Thermally activated carbon has been prepared from palm kernel shell at 1073 K and placed under nitrogen flow for 2 h. It was impregnated by palladium using toluene solution of Pd (acac2. The Pd/C was reduced using a water solution of potassium borohydride (KBH4. The Pd-B/C was characterized by the Brunauer-Emmett-Teller surface area analysis (BET, scanning electron microscopy (SEM, transmission electron microscopy (TEM and inductively-coupled plasma mass spectrometry (ICP-MS. Pd-B/C was applied for sunflower oil hydrogenation at a temperature of 373 K, hydrogen pressure of 413.5 kPa and agitation of 1400 rpm for 1 h. Pd-B/C noticeably exhibited a higher overall catalyst activity in comparison to some recently published palladium catalysts.

  11. Green synthesis of silver and gold nanoparticles employing levan, a biopolymer from Acetobacter xylinum NCIM 2526, as a reducing agent and capping agent.

    Science.gov (United States)

    Ahmed, Khan Behlol Ayaz; Kalla, Divya; Uppuluri, Kiran Babu; Anbazhagan, Veerappan

    2014-11-01

    With a vision of finding greener materials to synthesize nanoparticles, we report the production and isolation of levan, a polysaccharide with repeating units of fructose, from Acetobacter xylinum NCIM2526. The isolated levan were characterized using potassium ferricyanide reducing power assay, Fourier transform infra-red (FTIR) spectroscopy and (1)H nuclear magnetic resonance spectroscopy ((1)H NMR). To exploit levan in nanotechnology, we present a simple and greener method to synthesize silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) using biopolymer, levan as both reducing and stabilizing agents. The morphology and stability of the AgNPs and AuNPs were examined by transmission electron microscopy (TEM) and UV-vis absorption (UV-vis) spectroscopy. The possible capping mechanism of the nanoparticles was postulated using FTIR studies. As synthesized biogenic nanoparticles showed excellent catalytic activity as evidenced from sodium borohydride mediated reduction of 4-nitro phenol and methylene blue. PMID:25129779

  12. Ultrasound assisted green synthesis of poly(vinyl alcohol) capped silver nanoparticles for the study of its antifilarial efficacy

    Science.gov (United States)

    Saha, Swadhin Kr.; Chowdhury, Pranesh; Saini, Prasanta; Babu, Santi P. Sinha

    2014-01-01

    Poly(vinyl alcohol) (PVA) capped stable silver nanoparticles (AgNP) have been synthesized sonochemically with the help of catalytic amount of a biomolecule (tyrosine). An attempt has been made to reduce the harmfull chemical additives (like sodium borohydride, hydrazine, dimethyl formamide, etc.) used in conventional methods. Tyrosine shows excellent reducing activity in presence of PVA stabilizer. Ultra-sound increased the reaction rate and yield, and improved the quality of the AgNP in terms of regular size distribution. The synthetic route follows the principles of green chemistry. Bioactivity has been tested in the light of antifilarial efficacy through induction of apoptosis. The biocompatible polymer (PVA) capped AgNPs are suitable for the treatment of filarial nematode.

  13. Gold Incorporated Mesoporous Silica Thin Film Model Surface as a Robust SERS and Catalytically Active Substrate

    Directory of Open Access Journals (Sweden)

    Anandakumari Chandrasekharan Sunil Sekhar

    2016-05-01

    Full Text Available Ultra-small gold nanoparticles incorporated in mesoporous silica thin films with accessible pore channels perpendicular to the substrate are prepared by a modified sol-gel method. The simple and easy spin coating technique is applied here to make homogeneous thin films. The surface characterization using FESEM shows crack-free films with a perpendicular pore arrangement. The applicability of these thin films as catalysts as well as a robust SERS active substrate for model catalysis study is tested. Compared to bare silica film our gold incorporated silica, GSM-23F gave an enhancement factor of 103 for RhB with a laser source 633 nm. The reduction reaction of p-nitrophenol with sodium borohydride from our thin films shows a decrease in peak intensity corresponding to –NO2 group as time proceeds, confirming the catalytic activity. Such model surfaces can potentially bridge the material gap between a real catalytic system and surface science studies.

  14. Silver nanoparticles prepared by chemical reduction-protection method, and their application in electrically conductive silver nanopaste

    Energy Technology Data Exchange (ETDEWEB)

    Liu Jianguo, E-mail: ljg712@yahoo.com.c [Wuhan National Laboratory for Optoelectronics, College of Optoelectronics Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Li Xiangyou; Zeng Xiaoyan [Wuhan National Laboratory for Optoelectronics, College of Optoelectronics Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

    2010-04-02

    Ag nanoparticles were prepared in a water-phase system with a mixture of silver-ammonia complex, sodium borohydride, and lauric acid according to molar feed ratio of approximately 6:3:1. The mechanism of preparation and separation by chemical reduction-protection method was explored. The as-synthesized Ag nanoparticles were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-vis spectroscopy, respectively. It was found that the size of high purity Ag particles was ranging from 30 to 50 nm with slight agglomeration. In addition, the as-synthesized wet Ag nanoparticles were dispersed stably in organic vehicle to formulate electrically conductive nanopaste. Upon direct-written and sintered, the array pattern of the nanopaste with the resolution of about 30 {mu}m was achieved with the electrical resistivity in the order of magnitude of 10{sup -5} {Omega} cm.

  15. Preparation of nickel nanoparticles in emulsion

    Institute of Scientific and Technical Information of China (English)

    ZHANG You-xian; FU Wen-jie; AN Xue-qin

    2008-01-01

    The nickel nanoparticles with different sizes and spherical shape were prepared by the reduction of nickel sulfate with sodium borohydride in the water-in-oil emulsions of water/SDBS(sodium dodecylbenzene sulfonate)/n-pentanol/n-heptane. The effects of aging time, molar ratio of water to SDBS(R) and the concentration of nickel sulfate on the size of particles were studied. The samples were characterized by transmission electron microscopy(TEM) and inductively coupled plasma spectrometry(ICP). The results show that the average particle size changes from 20 to 40 nm by adjusting aging time (15-30 min) and R (9-11.5). The concentration of nickel sulfate of 1.0 mol/L is the favorite condition.

  16. Fabrication And Properties Of Silver Based Multiwall Carbon Nanotube Composite Prepared By Spark Plasma Sintering Method

    Directory of Open Access Journals (Sweden)

    Lis M.

    2015-06-01

    Full Text Available The paper presents results of investigations of the obtained nanocomposite materials based on silver with addition of multiwall carbon nanotubes. The powder of carbon nanotubes content from 0.1 to 3 wt. % was produced by application of powder metallurgy methods, through mixing and high-energetic milling, and also chemical methods. Modification of carbon nanotubes included electroless deposition of silver particles on the carbon nanotube active surfaces and chemical reduction with strong reducing agent – sodium borohydride (NaBH4. The obtained powder mixtures were consolidated by SPS – Spark Plasma Sintering method. The formed composites were subjected to tests of relative density, electrical conductivity and electro-erosion properties. Detailed examinations of the structure with application of X-ray microanalysis, with consideration of carbon nanotubes distribution, were also carried out. The effect of manufacturing methods on properties of the obtained composites was observed.

  17. Thermoregulated Coacervation, Metal-Encapsulation and Nanoparticle Synthesis in Novel Triazine Dendrimers.

    Science.gov (United States)

    Ramírez-Crescencio, Fermín; Enciso, Alan E; Hasan, Mirza; da Costa, Viviana C P; Annunziata, Onofrio; Redón, Rocío; Coffer, Jeffery L; Simanek, Eric E

    2016-01-01

    The synthesis and solubility behaviors of four generation five (G5) triazine dendrimers are studied. While the underivatized cationic dendrimer is soluble in water, the acetylated and propanoylated derivatives undergo coacervation in water upon increasing temperature. Occurring around room temperature, this behavior is related to a liquid-liquid phase transition with a lower critical solution temperature (LCST) and is explained by differences in composition, notably, the hydrophobic nature of the terminal groups. Interestingly, the water solubility of the acetylated dendrimer is affected by the addition of selected metal ions. Titrating solutions of acetylated dendrimer at temperatures below the LCST with gold or palladium ions promoted precipitation, but platinum, iridium, and copper did not. Gold nanoparticles having diameters of 2.5 ± 0.8 nm can be obtained from solutions of the acetylated dendrimer at concentrations of gold less than that required to induce precipitation by treating the solution with sodium borohydride. PMID:27187331

  18. Preparation of silver nanoparticles at low temperature

    Science.gov (United States)

    Mishra, Mini; Chauhan, Pratima

    2016-04-01

    Silver from ancient time is used as antimicrobial agent in the bulk form but now with the advancement in nanotechnology silver in the form of nanoparticles shown potential effect against microbes which make us easy to fight with many diseases plants and animals. In this work silver nanoparticles were synthesized by chemical routes using sodium borohydride as reducing agent at low temperature. The particles were characterized through UV-Visible spectroscopy as well as X-Ray Diffraction. The UV-visible spectra of silver nanoparticles exhibited absorption at 425 cm; the crystallite size of the particles is between 19nm to 39nm. EDAX graph shows two peaks of silver and oxygen. Water absorbed by silver nanoparticles was removed by the calcinations.

  19. 碱熔、氢化物原子荧光光谱法测定土壤中微量锗%FLUORESCENCE SPECTROMETRY

    Institute of Scientific and Technical Information of China (English)

    陈锡海; 王国成

    2011-01-01

    Acidize sample that has been subjected to alkali fusion.Determine the content of germanium in phosphate medium with potassium borohydride as reducing agent,by using atomic fluorescence spectrometry.The detection limit of the method is 0.1μg/g.It was used to test 6 national level 1 soil samples and gave results consistent to recommended values.Respective test of 12 times gave RSD all below 10%.%将碱熔后的样品酸化,在磷酸介质中,以硼氢化钾为还原剂,用原子荧光光谱法测定锗的含量。该法的检出限为0.1μg/g,,测定的六个国家一级土样与推荐值相符,并且各自测定12次的RSD均小于10%。

  20. Active targeting of cancer cells using folic acid-conjugated platinum nanoparticles

    Science.gov (United States)

    Teow, Yiwei; Valiyaveettil, Suresh

    2010-12-01

    Interaction of nanoparticles with human cells is an interesting topic for understanding toxicity and developing potential drug candidates. Water soluble platinum nanoparticles were synthesized viareduction of hexachloroplatinic acid using sodium borohydride in the presence of capping agents. The bioactivity of folic acid and poly(vinyl pyrrolidone) capped platinum nanoparticles (Pt-nps) has been investigated using commercially available cell lines. In the cell viability experiments, PVP-capped nanoparticles were found to be less toxic (>80% viability), whereas, folic acid-capped platinum nanoparticles showed a reduced viability down to 24% after 72 h of exposure at a concentration of 100 μg ml-1 for MCF7 breast cancer cells. Such toxicity, combined with the possibility to incorporate functional organic molecules as capping agents, can be used for developing new drug candidates.

  1. Lignin Sulfonation - A different Approach

    DEFF Research Database (Denmark)

    Bjørkmann, Anders

    2001-01-01

    The research on sulfite pulping has been characterized by the attempts to explain its chemistry. The. different approach presented is incited by perceptions about the (still) unsolved problem of the ultrastructural features of lignin in wood. A simple kinetic model has been chosen to describe the...... reaction order of lignin as "concentration" (weight) in the dissolution kinetics, the cooking liquor being used in substantial excess. Three states of lignin were used: in wood as sawdust (W), in milled. wood (MW) and as milled wood lignin (MWL). Cooks were performed at pH 1.5, and 6. (measured at room...... temperature). The lignin was also modified chemically in two ways: alkaline borohydride reduction and diazomethane methylation. The reaction order (with the kinetics used) was found to be about 2/3, which is the value to be expected for particles of equal size reacting, at the particle surface. The cooks were...

  2. Preparation, characterization, and antibacterial activity studies of silver-loaded poly(styrene-co-acrylic acid) nanocomposites.

    Science.gov (United States)

    Song, Cunfeng; Chang, Ying; Cheng, Ling; Xu, Yiting; Chen, Xiaoling; Zhang, Long; Zhong, Lina; Dai, Lizong

    2014-03-01

    A simple method for preparing a new type of stable antibacterial agent was presented. Monodisperse poly(styrene-co-acrylic acid) (PSA) nanospheres, serving as matrices, were synthesized via soap-free emulsion polymerization. Field-emission scanning electron microscopy micrographs indicated that PSA nanospheres have interesting surface microstructures and well-controlled particle size distributions. Silver-loaded poly(styrene-co-acrylic acid) (PSA/Ag-NPs) nanocomposites were prepared in situ through interfacial reduction of silver nitrate with sodium borohydride, and further characterized by transmission electron microscopy and X-ray diffraction. Their effects on antibacterial activity including inhibition zone, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and bactericidal kinetics were evaluated. In the tests, PSA/Ag-NPs nanocomposites showed excellent antibacterial activity against both gram-positive Staphylococcus aureus and gram-negative Escherichia coli. These nanocomposites are considered to have potential application in antibacterial coatings on biomedical devices to reduce nosocomial infection rates. PMID:24433897

  3. Facilely Tuning Porous NiCo2 O4 Nanosheets with Metal Valence-State Alteration and Abundant Oxygen Vacancies as Robust Electrocatalysts Towards Water Splitting.

    Science.gov (United States)

    Zhu, Chengzhou; Fu, Shaofang; Du, Dan; Lin, Yuehe

    2016-03-14

    Great efforts in developing clean electrochemical water splitting technology leads to the rational design and synthesis of highly efficient oxygen evolution reaction (OER) catalysts with low overpotential and fast reaction kinetics. Herein, we focus on the role that morphology and composition play in the OER performance to rationally design freestanding 3D porous NiCo2O4 nanosheets with metal valence states alteration and abundant oxygen vacancies as robust electrocatalysts towards water splitting. Besides metal valence-state alteration, surface modification regarding the evolution of oxygen vacancies is facilely realized upon the sodium borohydride treatment, which is beneficial for the enhanced OER performance. Taking advantage of the porous nanostructures and abundant surface activity sites with high reactivity, the resultant nanostructures exhibit excellent OER activity and stability in alkaline electrolytes that outperform that of pristine NiCo2O4 and commercial RuO2, thus holding great potential for the water splitting. PMID:26845062

  4. Nonenzymatic sensing of glucose at neutral pH values and low working potential using a glassy carbon electrode modified with platinum-iron alloy nanoparticles on a carbon support

    International Nuclear Information System (INIS)

    Alloy nanoparticles of the type PtxFe (where x is 1, 2 or 3) were synthesized by coreduction with sodium borohydride in the presence of carbon acting as a chemical support. The resulting nanocomposites were characterized by scanning electron microscopy and X-ray diffraction. The nanocomposite was placed on a glassy carbon electrode, and electrochemical measurements indicated an excellent catalytic activity for the oxidation of glucose even a near-neutral pH values and at a working voltage as low as 50 mV (vs. SCE). Under optimized conditions, the sensor responds to glucose in the 10.0 μM to 18.9 mM concentration range and with a 3.0 μM detection limit (at an S/N ratio of 3). Interferences by ascorbic acid, uric acid, fructose, acetamidophenol and chloride ions are negligible. (author)

  5. Development of 3-methoxy-4-benzyloxybenzyl alcohol (MBBA) resin as polymer-supported synthesis support: Preparation and benzyl ether cleavage by DDQ oxidation

    Indian Academy of Sciences (India)

    Qiang Huang; Bao-Zhong Zheng; Quan Long

    2010-03-01

    3-Methoxy-4-benzyloxybenzyl alcohol (MBBA) resin was synthesized by a two-step sequence under microwave irradiation involving the reaction of commercially available Merrifield resin with vanillin, followed by reduction with sodium borohydride. MBBA resin was treated with bromides in the presence of sodium hydride to afford the corresponding resin-bound benzyl ethers. Cleavage of the resin-bound benzyl ethers from the MBBA resin was carried out using 2,3-dichloro-5,6-dicyanobenzoqunone (DDQ) to give the corresponding alcohols in good yields. Moreover, the recovery, regeneration, and reuse of this polymer support could be achieved easily. MBBA resin can be developed as a kind of solid-phase synthesis bead of alcohols.

  6. Thermoregulated Coacervation, Metal-Encapsulation and Nanoparticle Synthesis in Novel Triazine Dendrimers

    Directory of Open Access Journals (Sweden)

    Fermín Ramírez-Crescencio

    2016-05-01

    Full Text Available The synthesis and solubility behaviors of four generation five (G5 triazine dendrimers are studied. While the underivatized cationic dendrimer is soluble in water, the acetylated and propanoylated derivatives undergo coacervation in water upon increasing temperature. Occurring around room temperature, this behavior is related to a liquid-liquid phase transition with a lower critical solution temperature (LCST and is explained by differences in composition, notably, the hydrophobic nature of the terminal groups. Interestingly, the water solubility of the acetylated dendrimer is affected by the addition of selected metal ions. Titrating solutions of acetylated dendrimer at temperatures below the LCST with gold or palladium ions promoted precipitation, but platinum, iridium, and copper did not. Gold nanoparticles having diameters of 2.5 ± 0.8 nm can be obtained from solutions of the acetylated dendrimer at concentrations of gold less than that required to induce precipitation by treating the solution with sodium borohydride.

  7. Experimental Study of Interfacial Friction in NaBH{sub 4} Solution in Microchannel Dehydrogenation Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Seok Hyun; Hwang, Sueng Sik; Lee, Hee Joon [Kookmin Univ., Seoul (Korea, Republic of)

    2014-02-15

    Sodium borohydride (NaBH{sub 4}) is considered as a secure metal hydride for hydrogen storage and supply. In this study, the interfacial friction of two-phase flow in the dehydrogenation of aqueous NaBH{sub 4} solution in a microchannel with a hydraulic diameter of 461 μm is investigated for designing a dehydrogenation chemical reactor flow passage. Because hydrogen gas is generated by the hydrolysis of NaBH{sub 4} in the presence of a ruthenium catalyst, two different flow phases (aqueous NaBH{sub 4} solution and hydrogen gas) exist in the channel. For experimental studies, a microchannel was fabricated on a silicon wafer substrate, and 100-nm ruthenium catalyst was deposited on three sides of the channel surface. A bubbly flow pattern was observed. The experimental results indicate that the two-phase multiplier increases linearly with the void fraction, which depends on the initial concentration, reaction rate, and flow residence time.

  8. Synthesis of camptothecin-loaded gold nanomaterials

    International Nuclear Information System (INIS)

    Camptothecin-loaded gold nanomaterials have been synthesized by the sodium borohydride reduction method under a strong basic condition. The obtained gold nanomaterials have been characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM) and UV-vis absorption spectroscopy. The camptothecin-loaded gold colloidal solution was very stable and can be stored for more than two months at room temperature without obvious changes. The color of the colloidal solution can change from wine red to purple and blue during the acidifying process. It was revealed that the release of camptothecin and the aggregation of gold nanoparticles can be controlled by tuning the solution pH. The present study implied that the gold nanomaterials can be used as the potential carrier for CPT delivery.

  9. A New Method of Preparing Alkanethiol-Protected Gold Nanoparticals

    Institute of Scientific and Technical Information of China (English)

    HU Xiao-ya; XU Qin; GUO Rong

    2003-01-01

    In a new two-phase system ( tetrahydrofuran/ saturated NaCl aqueous solution ) monolayer protected clusters ( MPCs ) were prepared. The AuCl-4 anion in saturated electrolyte aqueous solution was transferred into the organic phase of tetrahydrofuran by tetra-n-butylammoniun bromide ( ( C4 H9 )4 NBr )and was reduced quickly by sodium borohydride in the presence of alkanethiol. The functionalized MPCs were characterized by solubility , transmission electron microscopy (TEM), Fourier transform infrared spectroscopy ( FTIR ), energy-dispersive X-ray (EDX) analysis and UV-vis spectroscopy. Electrochemical measurements of MPCs in CH2 Cl2 exhibited 7 pairs of reversible voltammetric waves within the potential range of - 1.0 to 1.0 V ( vs Ag/ AgCl ), which was ascribed to the quantized capacitance charging of nanoparticle double layers. All the results show that the new preparing method is feasible.

  10. Structure determination of the neutral exopolysaccharide produced by Lactobacillus delbrueckii subsp. bulgaricus OLL1073R-1.

    Science.gov (United States)

    Van Calsteren, Marie-Rose; Gagnon, Fleur; Nishimura, Junko; Makino, Seiya

    2015-09-01

    The neutral exopolysaccharide (NPS) of Lactobacillus delbrueckii subsp. bulgaricus strain OLL1073R-1 was purified and characterized. The molecular mass was 5.0×10(6) g/mol. Sugar and absolute configuration analyses gave the following composition: d-Glc, 1; d-Gal, 1.5. The NPS was also submitted to periodate oxidation followed by borohydride reduction and Smith degradation. Sugar and methylation analyses, (1)H and (13)C nuclear magnetic resonance, and mass spectrometry of the NPS or of its specifically modified products allowed determining the repeating unit sequence: {2)Glc(α1-3)Glc(β1-3)[Gal(β1-4)]Gal(β1-4)Gal(α1-}n. The structure is compared to that of exopolysaccharides produced by other Lactobacillus bulgaricus strains.

  11. Reversible hydrogen storage materials

    Science.gov (United States)

    Ritter, James A.; Wang, Tao; Ebner, Armin D.; Holland, Charles E.

    2012-04-10

    In accordance with the present disclosure, a process for synthesis of a complex hydride material for hydrogen storage is provided. The process includes mixing a borohydride with at least one additive agent and at least one catalyst and heating the mixture at a temperature of less than about 600.degree. C. and a pressure of H.sub.2 gas to form a complex hydride material. The complex hydride material comprises MAl.sub.xB.sub.yH.sub.z, wherein M is an alkali metal or group IIA metal, Al is the element aluminum, x is any number from 0 to 1, B is the element boron, y is a number from 0 to 13, and z is a number from 4 to 57 with the additive agent and catalyst still being present. The complex hydride material is capable of cyclic dehydrogenation and rehydrogenation and has a hydrogen capacity of at least about 4 weight percent.

  12. A novel Ag catalyzation process using swelling impregnation method for electroless Ni deposition on Kevlar® fiber

    Science.gov (United States)

    Pang, Hongwei; Bai, Ruicheng; Shao, Qinsi; Gao, Yufang; Li, Aijun; Tang, Zhiyong

    2015-12-01

    A novel Ag catalyzation process using swelling impregnation pretreatment method was developed for electroless nickel (EN) deposition on Kevlar fiber. Firstly, the fiber was immersed into an aqueous dimethylsulfoxide (DMSO) solution of silver nitrate to impart silver nitrate into the inner part of the fiber near the surface. Subsequently silver nitrate was reduced to metal silver nanoparticles on the fiber surface by treatment with aqueous solution of sodium borohydride. After electroless plating, a dense and homogeneous nickel coating was obtained on the fiber surface. The silver nanoparticles formed at the fiber surface functioned as a catalyst for electroless deposition as well as an anchor for the plated layer. The study also revealed that the incorporation of surfactant sodium dodecyl sulfate (SDS) in electroless nickel plating bath can enhance the adhesion strength of EN layer with the fiber surface and minimize the surface roughness of the EN coating. The Ni plated Kevlar fiber possessed excellent corrosion resistance and high tensile strength.

  13. Room-temperature synthesis and electrocatalysis of carbon nanotubes supported palladium–iron alloy nanoparticles

    International Nuclear Information System (INIS)

    Carbon nanotubes (CNTs) supported palladium–iron bimetallic nanoparticles (Pd–Fe/CNTs) catalyst is synthesized using palladium hexacyanoferrate (PdHCF) as reaction precursor. In this method, the negatively charged PdHCF nanoparticles self-assemble on the positively charged polydiallyldimethylammonium chloride (PDDA) functionalized CNTs through electrostatic interaction, and then are reduced to Pd–Fe alloy nanoparticles by sodium borohydride. The physicochemical properties of Pd–Fe/CNTs are investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). These structural analyses reveal that the Pd–Fe/CNTs catalyst possesses the high alloying degree and the small particle size. Electrochemical measurements show that the eletrocatalytic activity of the Pd–Fe/MWCNTs catalyst for the methanol oxidation is better than that of the Pd/CNTs catalyst, which originates from the synergistic effect between Pd atom and Fe atom

  14. Collagen cross-linking of skin in patients with amyotrophic lateral sclerosis

    Science.gov (United States)

    Ono, S.; Yamauchi, M.

    1992-01-01

    Collagen cross-links of skin tissue (left upper arm) from 11 patients with amyotrophic lateral sclerosis (ALS) and 9 age-matched control subjects were quantified. It was found that patients with ALS had a significant reduction in the content of an age-related, stable cross-link, histidinohydroxylysinonorleucine, that was negatively correlated with the duration of illness. The contents of sodium borohydride-reducible labile cross-links, dehydro-hydroxylysinonorleucine and dehydro-histidinohydroxymerodesmosine, were significantly increased and were positively associated with the duration of illness (r = 0.703, p less than 0.05 and r = 0.684, p less than 0.05, respectively). The results clearly indicate that during the course of ALS, the cross-linking pathway of skin collagen runs counter to its normal aging, resulting in a "rejuvenation" phenomenon of skin collagen. Thus, cross-linking of skin collagen is affected in ALS.

  15. Technetium-99m radiolabeling of a recombinant dermonecrotic protein (recLiD1) from the Loxosceles venom for biodistribution study

    Energy Technology Data Exchange (ETDEWEB)

    Valadares, D.; Felicori, L.; Olortegui, C.C. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Bioquimica e Imunologia; Simal, C. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Faculdade de Medicina; Gouvea dos Santos, R. [Centro de Desenvolvimento da Tecnologia Nuclear CDTN/CNEN-MG, Belo Horizonte, MG (Brazil). Lab. de Radiobiologia]. E-mail: santosr@cdtn.br

    2007-07-01

    In the present study the recombinant form (recLiD1) of a dermonecrotic protein present in the Brazilian brown spider Loxosceles intermedia venom was labeled with technetium-99m using stannous chloride and sodium borohydride as reducing agents. 99mTc-recLiD 1 kept its biological activity evoking dermonecrotic activity in rabbits. In vivo biodistribution in mice with the radiolabeled recLiD 1 showed high kidney uptake followed by stomach and liver uptakes. Also, we can see that 20% of toxin remaining in the skin after 120 min and once absorbed, 99mTc-recLiD 1 is rapidly cleared from the blood with long-lasting. We also observed one displacement of 99mTc-recLiD 1 by one monoclonal antibody raised against L. intermedia venom that indicates specific interaction with kidney tissue. (author)

  16. Development of carborane synthons: Synthesis and chemistry of (aminoalkyl)carboranes

    International Nuclear Information System (INIS)

    A number of (aminoalkyl)-1,2-closo-dodecaboranes have been synthesized to provide carboranes with a functional group for covalent incorporation into structures of potential use in the treatment of cancer by boron neutron capture therapy (BNCT). (Phthalimidoalkyl)acetylenes reacted with decaborane to give the corresponding carboranes; removal of the phthalimido group under mild conditions using sodium borohydride in 2-propanol furnished the (aminoalkyl)carboranes which were isolated as their hydrochloride salts. An alternative approach involved the conversion of an (iodoalkyl)- or a ((tosyloxy)alkyl)carborane to the azido derivative which gave the amine on hydrogenation. An effective way of attaching a carborane moiety to thiouracil, which is selectively taken up in melanoma cells, is illustrated by the acylation of two of these amines with thiouracil-5-carboxylic acid

  17. Comparison of polypeptides from cultured human fibroblasts and sarcoma cells.

    Science.gov (United States)

    Vartio, T; Kaelin, H; Vaheri, A

    1978-10-23

    The proteins in cell layers of cultured normal diploid human skin (ES, ER) and lung (WI-38) fibroblasts were compared to those of SV40-transformed human fibroblasts (WI-38/VA-13), human rhabdomyosarcoma (RD) and fibrosarcoma (HT-1080) cells using metabolic amino acid and sugar labeling and surface labeling with tritiated sodium borohydride after oxidation with galactose oxidase. The labeled proteins were analysed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and autoradiography (fluorography). A transformation-associated decrease in the pericellular glycoprotein fibronectin (subunit molecular weight, 220 000) and in the synthesis of a set of polypeptides in the 130 000--180 000 dalton region was seen. Synthesis of a glycosylated 160 000 dalton polypeptide was markedly reduced. In transformed cells distinct increases of several specific polypeptides was detected in both [35S]methionine and [3H] mannose incorporation experiments but not using the surface labeling method.

  18. Water- and organo-dispersible gold nanoparticles supported by using ammonium salts of hyperbranched polystyrene: preparation and catalysis.

    Science.gov (United States)

    Gao, Lei; Nishikata, Takashi; Kojima, Keisuke; Chikama, Katsumi; Nagashima, Hideo

    2013-12-01

    Gold nanoparticles (1 nm in size) stabilized by ammonium salts of hyperbranched polystyrene are prepared. Selection of the R groups provides access to both water- and organo-dispersible gold nanoparticles. The resulting gold nanoparticles are subjected to studies on catalysis in solution, which include reduction of 4-nitrophenol with sodium borohydride, aerobic oxidation of alcohols, and homocoupling of phenylboronic acid. In the reduction of 4-nitrophenol, the catalytic activity is clearly dependent on the size of the gold nanoparticles. For the aerobic oxidation of alcohols, two types of biphasic oxidation are achieved: one is the catalyst dispersing in the aqueous phase, whereas the other is in the organic phase. The catalysts are reusable more than four times without loss of the catalytic activity. Selective synthesis of biphenyl is achieved by the homocoupling of phenylboronic acid catalyzed by organo-dispersible gold nanoparticles.

  19. 龙脑烯基环己醇型檀香化合物的合成研究%Study on the synthesis of campholenyl cyclohexanol type sandalwood compounds

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Campholenyl cyclohexanol type compounds, having precious sandalwoods-like aroma,were prepared from camphorenal,piperidine,MVK,PTSH catalyst,etc. via intermediate of enamine,additive reaction of Michael, cyclization in the molecule,and reduction by sodium borohydride, The reaction conditions and mechanisms were discussed,the product structures and odor were identified also.%由龙脑烯醛、哌啶、甲基乙烯基酮、PTSH催化剂等原料,经烯胺中间体、Michael加成、分子内环化、硼氢化钠还原等反应,合成出了具有珍贵檀香香气的龙脑烯基环已醇型化合物。对合成条件及反应历程作了探讨,对产物的结构及香气怍了鉴定。

  20. Carbon Nanotubes Supported Pt-Ru-Ni as Methanol Electro-Oxidation Catalyst for Direct Methanol Fuel Cells

    Institute of Scientific and Technical Information of China (English)

    Fei Ye; Shengzhou Chen; Xinfa Dong; Weiming Lin

    2007-01-01

    Carbon nanotubes (CNTs) supported Pt-Ru and Pt-Ru-Ni catalysts were prepared by chemical reduction of metal precursors with sodium borohydride at room temperature. The crystallographic properties and composition of the catalysts were characterized by X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis, and the catalytic activity and stability for methanol electro-oxidation were measured by electrochemical impedance spectroscopy (EIS), linear sweep voltammetries (LSV), and chronoamperometry (CA). The results show that the catalysts exhibit face-centered cubic (fcc) structure.The particle size of Pt-Ru-Ni/CNTs catalyst is about 4.8 nm. The catalytic activity and stability of the Pt-Ru-Ni/CNTs catalyst are higher than those of Pt-Ru/CNTs catalyst.

  1. Dielectric relaxation and hopping conduction in reduced graphite oxide

    Science.gov (United States)

    Wei, Guidan; Yu, Ji; Gu, Min; Tang, Tong B.

    2016-06-01

    Graphite oxide reduced by sodium borohydride was characterised and its electrical conduction investigated with impedance spectroscopy. Thermal dependence of electrical modulus (instead of permittivity, its inverse) was calculated from complex impedance spectra, an approach that prevents any peak in dielectric loss (imaginary component) from being swarmed by large dc conductivity. Two loss peaks appeared at each tested frequency, in a sample of either degree of reduction. The set of weaker peak should arise from the relaxation of some polar bonds, as proposed earlier by us. The stronger loss peaks may correspond to the hopping of conduction electrons; variable range hopping is also consistent with the observed thermal dependence of conductivity. However, nearer ambient temperature there is a change in mechanism, to band transport, with an activation energy of fairly similar values as derived from both loss peaks and conductivity.

  2. Synthesis and characterization of stable aqueous dispersions of graphene

    Indian Academy of Sciences (India)

    Ujjal Kumar Sur; Abhijit Saha; Aparna Datta; Balaprasad Ankamwar; Farah Surti; Sannak Dutta Roy; Debasish Roy

    2016-02-01

    A stable aqueous dispersion (5 mg ml$^{−1}$) of graphene was synthesized by a simple protocol based on three-step reduction of graphene oxide (GO) dispersion synthesized using the modified version of Hummers and Offeman method. Reduction of GO was carried out using sodium borohydride, hydrazine hydrate and dimethyl hydrazine as reducing agents. The chemically synthesized graphene was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–visible absorption spectroscopy, Fourier transform infrared (FTIR) and Raman spectroscopy, thermogravimetric analysis (TGA), optical microscopy. The stability of aqueous dispersions of graphene was confirmed through zeta potential measurements and the negative zeta potentials of 55–60 mV were obtained indicating the high stability of aqueous graphene dispersions.

  3. A NEW POLYMER-BOUND 1,2-DIOL AS A PROTECTING AGENT FOR SYMMETRICAL DIALDEHYDE

    Institute of Scientific and Technical Information of China (English)

    REN Qisheng; HUANG Wenqiang; ZHAO Fengzhi; Ho Binglin

    1989-01-01

    A novel polymer- bound 1,2 - diol, 3 - polystyrylsulfonyl- 1,2 - propanediol (6) had ben prepared by the reaction of sodium polystyrylsulfinate with allyl bromide, followed by oxidation and. hydrolysis or directly with 3 - chloro - 1,2 - propanediol in the presence of a phase transfer catalyst ,n - tetrabutylammonium iodide. The capacity of resin 6 for terephthaldehyde reached 1.43 mmol/g. The aldehydic groups attached to polymer 6 reacted with hydroxylamine hydrochloride or reduced by sodium borohydride giving p-formylbenzaldoxime (yield:89%)and p-formyl -benzalcohol (yield:73 A % ), respectively. The high yields of these polymer-supported reactions showed that the polymer 6 possessed the effective isolation of its reactive sites.

  4. Stabilized rhodium(0) nanoparticles: a reusable hydrogenation catalyst for arene derivatives in a biphasic water-liquid system.

    Science.gov (United States)

    Schulz, J; Roucoux, A; Patin, H

    2000-02-18

    A colloidal system based on an aqueous suspension of rhodium(o) nanoparticles proved to be an efficient catalyst for the hydrogenation of arene derivatives under biphasic conditions. The rhodium nanoparticles (2-2.5 nm) were synthesized by the reduction of RhCl3 x 3H2O with sodium borohydride and were stabilized by highly water-soluble N-alkyl-N-(2-hydroxyethyl)ammonium salts (HEA-Cn). These surfactant molecules were characterized by measurements of the surface tension and the aqueous dispersions with rhodium were observed by transmission electron cryomicroscopy. The catalytic system is efficient under ultramild conditions, namely room temperature and 1 atm H2 pressure. The aqueous phase which contains the protected rhodium(0) colloids can be reused without significant loss of activity. The microheterogeneous behavior of this catalytic system was confirmed on a mercury poisoning experiment.

  5. Microstructure and magnetic properties of MFe2O4 (M = Co, Ni, and Mn) ferrite nanocrystals prepared using colloid mill and hydrothermal method

    International Nuclear Information System (INIS)

    Three kinds of spinel ferrite nanocrystals, MFe2O4 (M = Co, Ni, and Mn), are synthesized using colloid mill and hydrothermal method. During the synthesis process, a rapid mixing and reduction of cations with sodium borohydride (NaBH4) take place in a colloid mill then through a hydrothermal reaction, a slow oxidation and structural transformation of the spinel ferrite nanocrystals occur. The phase purity and crystal lattice parameters are estimated by X-ray diffraction studies. Scanning electron microscopy and transmission electron microscopy images show the morphology and particle size of the as-synthesized ferrite nanocrystals. Raman spectrum reveals active phonon modes at room temperature, and a shifting of the modes implies cation redistribution in the tetrahedral and octahedral sites. Magnetic measurements show that all the obtained samples exhibit higher saturation magnetization (Ms). Meanwhile, experiments demonstrate that the hydrothermal reaction time has significant effects on microstructure, morphologies, and magnetic properties of the as-synthesized ferrite nanocrystals

  6. Investigation of catalytic activity towards oxygen reduction reaction of Pt dispersed on boron doped graphene in acid medium.

    Science.gov (United States)

    Pullamsetty, Ashok; Sundara, Ramaprabhu

    2016-10-01

    Boron doped graphene was prepared by a facile method and platinum (Pt) decoration over boron doped graphene was done in various chemical reduction methods such as sodium borohydride (NaBH4), polyol and modified polyol. X-ray diffraction analysis indicates that the synthesized catalyst particles are present in a nanocrystalline structure and transmission and scanning electron microscopy were employed to investigate the morphology and particle distribution. The electrochemical properties were investigated with the help of the rotating disk electrode (RDE) technique and cyclic voltammetry. The results show that the oxygen reduction reaction (ORR) takes place by a four-electron process. The kinetics of the ORR was evaluated using K-L and Tafel plots. The electrocatalyst obtained in modified polyol reduction method has shown the better catalytic activity compared to other two electrocatalysts. PMID:27393888

  7. Silver-enhanced block copolymer membranes with biocidal activity

    KAUST Repository

    Madhavan, Poornima

    2014-11-12

    Silver nanoparticles were deposited on the surface and pore walls of block copolymer membranes with highly ordered pore structure. Pyridine blocks constitute the pore surfaces, complexing silver ions and promoting a homogeneous distribution. Nanoparticles were then formed by reduction with sodium borohydride. The morphology varied with the preparation conditions (pH and silver ion concentration), as confirmed by field emission scanning and transmission electron microscopy. Silver has a strong biocide activity, which for membranes can bring the advantage of minimizing the growth of bacteria and formation of biofilm. The membranes with nanoparticles prepared under different pH values and ion concentrations were incubated with Pseudomonas aeruginosa and compared with the control. The strongest biocidal activity was achieved with membranes containing membranes prepared under pH 9. Under these conditions, the best distribution with small particle size was observed by microscopy.

  8. Theoretical Studies on Dehydrogenation Reactions in Mg2(BH4)2(NH2)2 Compounds

    Institute of Scientific and Technical Information of China (English)

    Zheng Chen; Zhe-ning Chen; An-an Wu; Guo-tao Wu; Zhi-tao Xiong; Ping Chen; Xin Xu

    2012-01-01

    Borohydrides have been recently hightlighted as prospective new materials due to their high gravimetric capacities for hydrogen storage.It is,therefore,important to understand the underlying dehydrogenation mechanisms for further development of these materials.We present a systematic theoretical investigation on the dehydrogenation mechanisms of the Mg2(BH4)2(NH2)2 compounds.We found that dehydrogenation takes place most likely via the intermolecular process,which is favorable both kinetically and thermodynamically in comparison with that of the intramolecular process.The dehydrogenation of Mg2(BH4)2(NH2)2 initially takes place via the direct combination of the hydridic H in BH4-and the protic H in NH2-,followed by the formation of Mg-H and subsequent ionic recombination of Mg-Hδ-… Hδ+-N.

  9. Experimental Study of Interfacial Friction in NaBH4 Solution in Microchannel Dehydrogenation Reactor

    International Nuclear Information System (INIS)

    Sodium borohydride (NaBH4) is considered as a secure metal hydride for hydrogen storage and supply. In this study, the interfacial friction of two-phase flow in the dehydrogenation of aqueous NaBH4 solution in a microchannel with a hydraulic diameter of 461 μm is investigated for designing a dehydrogenation chemical reactor flow passage. Because hydrogen gas is generated by the hydrolysis of NaBH4 in the presence of a ruthenium catalyst, two different flow phases (aqueous NaBH4 solution and hydrogen gas) exist in the channel. For experimental studies, a microchannel was fabricated on a silicon wafer substrate, and 100-nm ruthenium catalyst was deposited on three sides of the channel surface. A bubbly flow pattern was observed. The experimental results indicate that the two-phase multiplier increases linearly with the void fraction, which depends on the initial concentration, reaction rate, and flow residence time

  10. Preparation of β-Artemether%β-蒿甲醚的制备

    Institute of Scientific and Technical Information of China (English)

    罗春; 黄建军; 杨柳; 谢小灵; 柳楚英

    2012-01-01

    β-Artemether was synthesized from artemisinin by reduction with potassium borohydride to give dihydroartemisinin, which was subjected to etherification with methanol in the presence of aluminum perchlorate nonahydrate followed by recrystallization with 50% methanol in 69% overall yield and 98.5% purity.%青蒿素经硼氢化钾还原制得双氢青蒿素,再在高氯酸铝作用下与甲醇成醚,用50%甲醇重结晶后可得到高纯度的β-蒿甲醚(1),总收率约69%,纯度可达98.5%.

  11. Study of Leishmania major-infected macrophages by use of lipophosphoglycan-specific monoclonal antibodies.

    Science.gov (United States)

    Handman, E

    1990-07-01

    Leishmania major infection of macrophages is followed by a time-dependent appearance of lipophosphoglycan (LPG) that can be detected on the surface of infected cells by monoclonal antibodies. The origin of these LPG epitopes is probably the intracellular amastigote. LPG epitopes could be detected on the amastigote and the infected macrophage by a number of monoclonal antibodies directed to several distinct determinants on the phosphoglycan moiety. The macrophage-expressed LPG may be modified because, unlike the parasite LPG as expressed on promastigotes or amastigotes, it could not be radiolabeled by galactose oxidase or periodate treatment of infected cells followed by reduction with 3H-labeled sodium borohydride. Some LPG epitopes displayed on the macrophage may be anchored with glycosylphosphatidylinositol, and some may be in the water-soluble phosphoglycan form bound to macrophage integrins involved in its specific recognition. The water-soluble population could be released from the infected macrophage by gentle protease treatment. PMID:1694823

  12. Studies on the effects of zerovalent iron nanoparticles on bacteria from the mangrove ecosystem.

    Science.gov (United States)

    Kharangate-Lad, Amrita; Pereira, Flancy; Fernandes, Julio; Bhosle, Saroj

    2016-01-01

    Zerovalent iron (ZVI) nanoparticles are gaining popularity in bioremediation of contaminated ground water and antimicrobial studies. In this study, ZVI nanoparticles were synthesized by borohydride method. The effect of these nanoparticles to alter the cell surface hydrophobicity of mangrove bacteria was studied by bacterial adhesion to hydrocarbon assay. The effect of these nanoparticles on the growth and extracellular polymeric substances (EPS) of a novel bacterial strain Halobacillus trueperi MXM-16 from mangroves was evaluated by growing the culture in the presence of ZVI nanoparticles and SEM. The change in the emulsifying ability of the cell-free supernatant of Halobacillus trueperi MXM-16 when grown in media amended with ZVI nanoparticles was also investigated by spectrophotometric analysis.

  13. Carbon supported trimetallic nickel-palladium-gold hollow nanoparticles with superior catalytic activity for methanol electrooxidation

    Science.gov (United States)

    Shang, Changshuai; Hong, Wei; Wang, Jin; Wang, Erkang

    2015-07-01

    In this paper, Ni nanoparticles (NPs) are prepared in an aqueous solution by using sodium borohydride as reducing agent. With Ni NPs as the sacrificial template, hollow NiPdAu NPs are successfully prepared via partly galvanic displacement reaction between suitable metal precursors and Ni NPs. The as-synthesized hollow NiPdAu NPs can well dispersed on the carbon substrate. Transmission electron microscopy, X-ray diffraction and inductively coupled plasma mass spectrometry are taken to analyze the morphology, structure and composition of the as-synthesized catalysts. The prepared catalysts show superior catalytic activity and stability for methanol electrooxidation in alkaline media compared with commercial Pd/C and Pt/C. Catalysts prepared in this work show great potential to be anode catalysts in direct methanol fuel cells.

  14. Two-dimensional self-organi-zation of 1-nonanethiol-capped gold nanoparticles

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A two-dimensional (2D) ordered hexagonal close-packed structure, formed by 1-nonanethiol-capped gold nanoparticles, is reported. The structure was constructed only by dipping the gold nanoparticle colloidal solution on flat substrate. The gold nanoparticles were synthesized as follows: First, AuCl4-1 was transferred from aqueous solution to toluene by the phase-transfer reagent of tetraoctylammo-nium bromide. Then it was reduced with aqueous sodium borohydride in the presence of a given amount of 1-nonanethiol molecules which was used to control the nuclea-tion and growth of the gold nanoparticles for the desired size. The experimental techniques, such as UV-Vis, FT-IR, and X-ray photoelectron spectroscopy (XPS), were employed to characterize the obtained product. Transmission electron microscopy (TEM) measurement demonstrated the size of the gold nanoparticle and the formation of two-dimensional ordered hexagonal close-packed gold nanoparticle structure.

  15. One-step growth of gold nanorods using a {beta}-diketone reducing agent

    Energy Technology Data Exchange (ETDEWEB)

    Tollan, Christopher M., E-mail: ctollan@cidetec.e [CIDETEC-Centre for Electrochemical Technologies, Parque Tecnologico de San Sebastian, New Materials Department (Spain); Echeberria, Jon [CEIT, Centro de Investigaciones Tecnicas de Guipuzcoa (Spain); Marcilla, Rebeca; Pomposo, Jose A.; Mecerreyes, David, E-mail: dmecerreyes@cidetec.e [CIDETEC-Centre for Electrochemical Technologies, Parque Tecnologico de San Sebastian, New Materials Department (Spain)

    2009-07-15

    The synthesis and characterisation of gold nanorods have been carried out by reduction of the gold salt HAuCl{sub 4}. This has been done using a single reducing agent, acetylacetone, rather than the two reducing agents, sodium borohydride and ascorbic acid, normally required by standard wet chemistry methods of gold nanorod formation. Using this novel method, the nanorods were synthesised at several different pH values which were found to greatly affect both the rate at which the nanorods form and their physical dimensions. The concentrations of acetylacetone and silver nitrate used relative to the gold salt were found to alter the aspect ratio of the nanorods formed. Rods with an average length of 42 nm and an aspect ratio of 4.6 can be easily and reproducibly formed at pH 10 using this method. Nanorods formed under optimum conditions were investigated using TEM.

  16. A twist on facial selectivity of hydride reductions of cyclic ketones: twist-boat conformers in cyclohexanone, piperidone, and tropinone reactions.

    Science.gov (United States)

    Neufeldt, Sharon R; Jiménez-Osés, Gonzalo; Comins, Daniel L; Houk, K N

    2014-12-01

    The role of twist-boat conformers of cyclohexanones in hydride reductions was explored. The hydride reductions of a cis-2,6-disubstituted N-acylpiperidone, an N-acyltropinone, and tert-butylcyclohexanone by lithium aluminum hydride and by a bulky borohydride reagent were investigated computationally and compared to experiment. Our results indicate that in certain cases, factors such as substrate conformation, nucleophile bulkiness, and remote steric features can affect stereoselectivity in ways that are difficult to predict by the general Felkin-Anh model. In particular, we have calculated that a twist-boat conformation is relevant to the reactivity and facial selectivity of hydride reduction of cis-2,6-disubstituted N-acylpiperidones with a small hydride reagent (LiAlH4) but not with a bulky hydride (lithium triisopropylborohydride).

  17. An easy and effective method for radiolabelling of solid lipid nanoparticles

    International Nuclear Information System (INIS)

    Nanoparticle biodistribution study is of great importance in bringing nanomedicine to patients. In this article, solid lipid nanoparticle (SLN) with dimension less than 100 nm was successfully radiolabelled with 99mTc by using sodium borohydride as a reducing agent (instead of stannous salts). Paclitaxel (PTX) was used as a model anticancer drug for the preparation of drug loaded SLN (PSLN). PSLN was characterized by standard methods. Encapsulation efficiency for PTX in PSLN was estimated by HPLC. PTX (Taxol formulation) and PSLN were radiolabelled separately and subsequent characterizations of these complexes were performed. Greater than 95 % radiolabelling efficiency was achieved and the labelling efficiency was calculated to be more than 90 % up to 24 h. Both the above-mentioned complexes passed the in vitro stability tests. PSLN achieved more brain concentration than Taxol as determined by biodistribution studies. This type of radiolabelling technique can be useful in preclinical evaluation of drug loaded SLN. (author)

  18. Camphor-mediated synthesis of carbon nanoparticles, graphitic shell encapsulated carbon nanocubes and carbon dots for bioimaging

    Science.gov (United States)

    Oza, Goldie; Ravichandran, M.; Merupo, Victor-Ishrayelu; Shinde, Sachin; Mewada, Ashmi; Ramirez, Jose Tapia; Velumani, S.; Sharon, Madhuri; Sharon, Maheshwar

    2016-02-01

    A green method for an efficient synthesis of water-soluble carbon nanoparticles (CNPs), graphitic shell encapsulated carbon nanocubes (CNCs), Carbon dots (CDs) using Camphor (Cinnamomum camphora) is demonstrated. Here, we describe a competent molecular fusion and fission route for step-wise synthesis of CDs. Camphor on acidification and carbonization forms CNPs, which on alkaline hydrolysis form CNCs that are encapsulated by thick graphitic layers and on further reduction by sodium borohydride yielded CDs. Though excitation wavelength dependent photoluminescence is observed in all the three carbon nanostructures, CDs possess enhanced photoluminescent properties due to more defective carbonaceous structures. The surface hydroxyl and carboxyl functional groups make them water soluble in nature. They possess excellent photostability, higher quantum yield, increased absorption, decreased cytotoxicity and hence can be utilized as a proficient bio imaging agent.

  19. Spectroscopic Studies of the Interaction of Silver Nanoparticles with Methylene Blue

    Institute of Scientific and Technical Information of China (English)

    Chuan DONG; Jun ZHANG; Dai-zi ZHOU

    2010-01-01

    The interaction between silver nanoparticles and Methylene Blue(MB)is studied by UV-Vis spectroscopy and fluorescence spectrometry.The UN-Vis absorption of the silver nanoparticles dramatically with the addition of MB.However,no obvious changes of absorption spectra of MB are observed when silver colloids ate added into the MB solution.In the presence of surfactant SDS,the catalysis of the silver nanoparticles in the reducton of MB by sodium borohydride is exhibited by UV-Vis and fluorescence spectroscopy of MB displaying faster response compared with the absence of the silver nanoparticles.The results show that the activity of surfactant SDS modified silver nanoparticles is great and a strong physical adsorption to MB exists.

  20. Self-assembled gold nanoparticles on functionalized gold(111) studied by scanning tunneling microscopy

    Institute of Scientific and Technical Information of China (English)

    PENG, Zhang-Quan; WANG, Er-Kang

    2000-01-01

    Nanogold colloidal solutions are prepared by the reduction of HAuClO4 with sodium citrate and sodium borohydride. 4- Aminothiophenol (ATP) self-assembled monolayers (SAMs) are formed on gold(111) surface, on which gold nanoparticles are immobilized and a sub-monolayer of the particles appears. This sub-monolayer of gold nanoparticles is characterized with scanning tunneling microscopy (STM), and a dual energy barrier tunneling model is proposed to explain the imgeability of the gold nanoparticles by STM. This model can also be used to construct multiple energy barrier structure on solid/ liquid interface and to evaluate the electron transport ability of some organic monolayers with the aid of electrochemical method.

  1. The synthesis of iron nickel alloy nanoparticles using a reverse micelle technique

    Science.gov (United States)

    Ban, Irena; Drofenik, Miha; Makovec, Darko

    2006-12-01

    Nanosized Fe 0.2Ni 0.8 particles were prepared by reducing their salts with sodium borohydride (NaBH 4) in cationic water-in-oil (w/o) microemulsions of water/cetyl-trimethyl-amonium bromide (CTAB) and n-butanol/isooctane at 25 °C. According to the TEM and X-ray diffraction analyses, the synthesized particles were around 4-12 nm in size. Due to their nanodimensions, the particles had a primitive cubic (pc) structure rather than the body-centered cubic (BCC) structure of the bulk material. An examination of the synthesis from the reverse micelle reveals that the morphology of the iron-nickel alloy nanoparticles depends mainly on the microemulsion's composition. The magnetization of the nanoparticles was much lower than that of the bulk material, reflecting the influence of the nanodimensions on the particles' magnetizations.

  2. Green synthesis of silver nanoparticles, decorated on graphene oxide nanosheets and their catalytic activity

    Science.gov (United States)

    Sreekanth, T. V. M.; Jung, Min-Ji; Eom, In-Yong

    2016-01-01

    In this study, we develop an inexpensive and green route for the synthesis of silver nanoparticles (AgNPs) using Picrasma quassioides bark aqueous extract as reducing and capping agent and also eco-friendly decorate graphene oxide (GO) nanosheets with AgNPs (GO-AgNPs). Green synthesized AgNPs and GO-AgNPs composites were characterized by UV-Visible spectroscopy, SEM-EDX, and TEM-SAED techniques. The resulting GO-AgNPs contained about 41.35% of Ag and the AgNPs size ranges 17.5-66.5 nm, and GO-AgNPs size ranges 10-49.5 nm. Moreover, the GO-AgNPs exhibited excellent catalytic activity towards the methylene blue (MB) in the presence of sodium borohydride (NaBH4) at room temperature. This catalytic reaction completed within 15 min.

  3. Green synthesis, characterization and catalytic activity of palladium nanoparticles by xanthan gum

    Science.gov (United States)

    Santoshi kumari, Amrutham; Venkatesham, Maragoni; Ayodhya, Dasari; Veerabhadram, Guttena

    2015-03-01

    Here, we report the synthesis, characterization and catalytic evaluation of palladium nanoparticles (PdNPs) using xanthan gum, acting as both reducing and stabilizing agent without using any synthetic reagent. The uniqueness of our method lies in its fast synthesis rates using hydrothermal method in autoclave at a pressure of 15 psi and at 120 °C temperature by 10 min time. The formation and size of the PdNPs were characterized by UV-visible spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy and transmission electron microscopy. The catalytic activity of PdNPs was evaluated on the reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride using spectrophotometry.

  4. Graphene sheets/cobalt nanocomposites as low-cost/high-performance catalysts for hydrogen generation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fei; Hou, Chengyi; Zhang, Qinghong [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); Wang, Hongzhi, E-mail: wanghz@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); Li, Yaogang, E-mail: yaogang_li@dhu.edu.cn [College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China)

    2012-08-15

    The production of clean and renewable hydrogen through the hydrolysis of sodium borohydride has received much attention owing to increasing global energy demands. Graphene sheets/cobalt (GRs/Co) nanocomposites, which are highly efficient catalysts, have been prepared using a one-step solvothermal method in ethylene glycol. Co{sup 2+} salts were converted to Co nanoparticles, which were simultaneously inserted into the graphene layers with the reduction of graphite oxide sheets to GRs. The as-synthesized samples were characterized by X-ray diffraction, Fourier transform infrared spectra, Raman spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy and vibrating sample magnetometer. The maximum saturation magnetization value reached 80.8 emu g{sup -1}, meaning they are more suitable for magnet-controlled generation of H{sub 2} than noble metal catalysts. The catalytic activity of the composite was investigated by the hydrolysis of sodium borohydride in aqueous solution both with and without a GRs support. It was found that the high electronic conductive GRs support increased the hydrogen generation rate (about two times) compared with pure cobalt. The improved hydrogen generation rate, low cost and uncomplicated recycling makes the GRs/Co nanocomposites promising candidates as catalysts for hydrogen generation. Highlights: Black-Right-Pointing-Pointer Graphene sheets/cobalt nanocomposites were prepared by a one-step solvothermal method. Black-Right-Pointing-Pointer The maximum saturation magnetization value of the composites reached 80.8 emu g{sup -1}. Black-Right-Pointing-Pointer The graphene support greatly increased the catalytic activity of cobalt. Black-Right-Pointing-Pointer An easily removed, recycled and controlled functional filter was obtained.

  5. 二氢苯骈[c]菲啶类生物碱的制备及其抗乙肝病毒的活性%Preparation of dihydrobenzo[c] phenanthridine alkaloids and evaluation of their anti-hepatitis B virus activity

    Institute of Scientific and Technical Information of China (English)

    吴颖瑞; 方宏; 牙始康; 何瑞杰

    2012-01-01

    二氢苯骈[c]菲啶类生物碱是自然界中一类重要的生物活性成分,但含量很低.利用硼氢化还原方法,对博落回粗提物中的血根碱和白屈菜红碱混合物进行还原、分离,得到了二氢血根碱和二氢白屈菜红碱;并初步评价了其抗乙肝病毒活性.结果表明,利用硼氢化还原方法制备二氢苯骈[c]菲啶类生物碱的产率较高,还原产物具有一定的抗乙肝病毒活性.%Dihydro-benzo[c]phenanthridine alkaloids are a kind of bioactive constituents, but their contents are very low in natural plants. Thus the mixture of sanguinarine and cheleryth-rine primarily extracted from Macleaya cordata (Willd) R B were reduced by sodium boro-hydride and separated into dihydrosanguinarine and dihydrochelerythrine. The anti-hepatitis B virus (HBV) activity of as-obtained dihydrosanguinarine and dihydrochelerythrine was evaluated. It has been found that phenonthridine alkaloids can be obtained in a high yield via the reduction of sanguinarine and chelerythrine by borohydride. As-obtained dihydrosanguinarine and dihydrochelerythrine products have some inhibitory effect against HBV (HBsAg secretions in Hep G2. 2.15 cell line).

  6. Preparation and characterization of electrocatalysts based on palladium for electro-oxidation of alcohols in alkaline medium

    International Nuclear Information System (INIS)

    In this study Pd/C, Au/C, PdAu/C, PdAuPt/C, PdAuBi/C and PdAuIr/C electrocatalysts were prepared by the sodium borohydride reduction method for the electrochemical oxidation of methanol, ethanol and ethylene glycol. This methodology consists in mix an alkaline solution of sodium borohydride to a mixture containing water/isopropyl alcohol, metallic precursors and the Vulcan XC 72 carbon support. The electrocatalysts were characterized by energy dispersive X-ray (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and cyclic voltammetry. The electrochemical oxidation of the alcohols was studied by chronoamperometry using a thin porous coating technique. The mechanism of ethanol electro-oxidation was studied by Fourier Transformed Infrared (FTIR) in situ. The most effective electrocatalysts were tested in alkaline single cells directly fed with methanol, ethanol or ethylene glycol. Preliminary studies showed that the most suitable atomic composition for preparing the ternary catalysts is 50:45:05. Electrochemical data in alkaline medium show that the electrocatalysts PdAuPt/C (50:45:05) showed the better activity for methanol electro oxidation, while PdAuIr/C was the most active for ethanol oxidation and PdAuBi/C (50:45:05) was the most effective for ethylene glycol oxidation in alkaline medium. These results show that the addition of gold in the composition of electrocatalysts increases their catalytic activities. The spectroelectrochemical FTIR in situ data permitted to conclude that C-C bond is not broken and the acetate is formed. (author)

  7. Boron-Based Hydrogen Storage: Ternary Borides and Beyond

    Energy Technology Data Exchange (ETDEWEB)

    Vajo, John J. [HRL Laboratories, LLC, Malibu, CA (United States)

    2016-04-28

    DOE continues to seek reversible solid-state hydrogen materials with hydrogen densities of ≥11 wt% and ≥80 g/L that can deliver hydrogen and be recharged at moderate temperatures (≤100 °C) and pressures (≤100 bar) enabling incorporation into hydrogen storage systems suitable for transportation applications. Boron-based hydrogen storage materials have the potential to meet the density requirements given boron’s low atomic weight, high chemical valance, and versatile chemistry. However, the rates of hydrogen exchange in boron-based compounds are thus far much too slow for practical applications. Although contributing to the high hydrogen densities, the high valance of boron also leads to slow rates of hydrogen exchange due to extensive boron-boron atom rearrangements during hydrogen cycling. This rearrangement often leads to multiple solid phases occurring over hydrogen release and recharge cycles. These phases must nucleate and react with each other across solid-solid phase boundaries leading to energy barriers that slow the rates of hydrogen exchange. This project sought to overcome the slow rates of hydrogen exchange in boron-based hydrogen storage materials by minimizing the number of solid phases and the boron atom rearrangement over a hydrogen release and recharge cycle. Two novel approaches were explored: 1) developing matched pairs of ternary borides and mixed-metal borohydrides that could exchange hydrogen with only one hydrogenated phase (the mixed-metal borohydride) and only one dehydrogenated phase (the ternary boride); and 2) developing boranes that could release hydrogen by being lithiated using lithium hydride with no boron-boron atom rearrangement.

  8. Anion- or Cation-Exchange Membranes for NaBH4/H2O2 Fuel Cells?

    Directory of Open Access Journals (Sweden)

    César A. C. Sequeira

    2012-07-01

    Full Text Available Direct borohydride fuel cells (DBFC, which operate on sodium borohydride (NaBH4 as the fuel, and hydrogen peroxide (H2O2 as the oxidant, are receiving increasing attention. This is due to their promising use as power sources for space and underwater applications, where air is not available and gas storage poses obvious problems. One key factor to improve the performance of DBFCs concerns the type of separator used. Both anion- and cation-exchange membranes may be considered as potential separators for DBFC. In the present paper, the effect of the membrane type on the performance of laboratory NaBH4/H2O2 fuel cells using Pt electrodes is studied at room temperature. Two commercial ion-exchange membranes from Membranes International Inc., an anion-exchange membrane (AMI-7001S and a cation-exchange membrane (CMI-7000S, are tested as ionic separators for the DBFC. The membranes are compared directly by the observation and analysis of the corresponding DBFC’s performance. Cell polarization, power density, stability, and durability tests are used in the membranes’ evaluation. Energy densities and specific capacities are estimated. Most tests conducted, clearly indicate a superior performance of the cation-exchange membranes over the anion-exchange membrane. The two membranes are also compared with several other previously tested commercial membranes. For long term cell operation, these membranes seem to outperform the stability of the benchmark Nafion membranes but further studies are still required to improve their instantaneous power load.

  9. Thermodynamic modelling of Mg(BH{sub 4}){sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Pinatel, E.R.; Albanese, E.; Civalleri, B.; Baricco, M.

    2015-10-05

    Highlights: • DFT calculations providing missing thermodynamic data for Mg(BH{sub 4}){sub 2}were performed. • A Calphad assessment of Mg(BH{sub 4}){sub 2} was performed, considering all the available data. • Stable and metastable phase diagrams have been calculated for Mg(BH{sub 4}){sub 2}. • Several dehydrogenation paths of Mg(BH{sub 4}){sub 2} have been analysed and discussed. - Abstract: Application of the Calphad method to the description of thermodynamic properties in complex borohydride-based systems may allow a faster development of hydrogen storage materials. It is, however, limited by the low number of available thermodynamic description for borohydrides in thermodynamic databases. In the present work, a Calphad assessment of Mg(BH{sub 4}){sub 2} has been performed, considering available thermodynamic data. DFT calculations have been performed in order to provide missing thermodynamic data and to calculate the relative stability of the α, β and γ polymorphs. Experimental results have been compared detecting inconsistencies between them. The database obtained has been used to estimate driving forces for several dehydrogenation reactions. The dehydrogenation reaction leading to the formation of MgB{sub 2} and gaseous hydrogen is the most favoured thermodynamically, even if at low temperatures the formation of MgB{sub 12}H{sub 12} is competitive. On the contrary, positive driving forces have been calculated for the decomposition into B{sub 2}H{sub 6} and Mg(B{sub 3}H{sub 8}){sub 2}.

  10. Synthesize Triangular Silver Nanoparticle by Photo-induced Reaction%光诱导合成三角板银纳米粒子的研究

    Institute of Scientific and Technical Information of China (English)

    杜虹; 赵淑贤; 董磊

    2011-01-01

    采用钠灯作为光诱导反应的光源,利用柠檬酸钠为稳定剂和结构导向剂,以硼氢化钠为还原剂,在水相中光诱导合成三角板银纳米粒子.考察了柠檬酸钠、硼氢化钠比例对粒子形貌的影响,确定最佳比例为[AgNO3]:[Na3C6H5O7]:[NaBH4]=1:25:0.4(物质的量比).采用透射电镜(TEM)、紫外可见吸收光谱(UV-Vis)、X-射线粉末衍射仪(XRD)对实验样品的形貌、光学性质及晶体结构进行表征.%Triangular silver naoplates were synthesized by irradiating the growth solution, which contained silver cations and citrate anions. The sodium lamp was chosen as the light source. The citrate anions in the system acted as stabilizers,and sodium borohydride acted as reducing agents. The spectral evolution of the growth process was monitored by the UV-vis spectrometer,and the corresponding shape,size and crystallo-graphic structure of nanoparticles in details were investigated by transmission electron microscope(TEM) and X-ray diffraction (XRD). We also estimated the influences of the molar ration between citrate anions and sodium borohydride on the final products.

  11. Preparation and characterization of electrocatalysts based on palladium for electro-oxidation of alcohols in alkaline medium; Preparacao e caracterizacao de eletrocatalisadores a base de paladio para oxidacao eletroquimica de alcoois em meio alcalino

    Energy Technology Data Exchange (ETDEWEB)

    Brandalise, Michele

    2012-07-01

    In this study Pd/C, Au/C, PdAu/C, PdAuPt/C, PdAuBi/C and PdAuIr/C electrocatalysts were prepared by the sodium borohydride reduction method for the electrochemical oxidation of methanol, ethanol and ethylene glycol. This methodology consists in mix an alkaline solution of sodium borohydride to a mixture containing water/isopropyl alcohol, metallic precursors and the Vulcan XC 72 carbon support. The electrocatalysts were characterized by energy dispersive X-ray (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and cyclic voltammetry. The electrochemical oxidation of the alcohols was studied by chronoamperometry using a thin porous coating technique. The mechanism of ethanol electro-oxidation was studied by Fourier Transformed Infrared (FTIR) in situ. The most effective electrocatalysts were tested in alkaline single cells directly fed with methanol, ethanol or ethylene glycol. Preliminary studies showed that the most suitable atomic composition for preparing the ternary catalysts is 50:45:05. Electrochemical data in alkaline medium show that the electrocatalysts PdAuPt/C (50:45:05) showed the better activity for methanol electro oxidation, while PdAuIr/C was the most active for ethanol oxidation and PdAuBi/C (50:45:05) was the most effective for ethylene glycol oxidation in alkaline medium. These results show that the addition of gold in the composition of electrocatalysts increases their catalytic activities. The spectroelectrochemical FTIR in situ data permitted to conclude that C-C bond is not broken and the acetate is formed. (author)

  12. Electrochemical hydrogen Storage Systems

    International Nuclear Information System (INIS)

    As the global need for energy increases, scientists and engineers have found a possible solution by using hydrogen to power our world. Although hydrogen can be combusted as a fuel, it is considered an energy carrier for use in fuel cells wherein it is consumed (oxidized) without the production of greenhouse gases and produces electrical energy with high efficiency. Chemical storage of hydrogen involves release of hydrogen in a controlled manner from materials in which the hydrogen is covalently bound. Sodium borohydride and aminoborane are two materials given consideration as chemical hydrogen storage materials by the US Department of Energy. A very significant barrier to adoption of these materials as hydrogen carriers is their regeneration from 'spent fuel,' i.e., the material remaining after discharge of hydrogen. The U.S. Department of Energy (DOE) formed a Center of Excellence for Chemical Hydrogen Storage, and this work stems from that project. The DOE has identified boron hydrides as being the main compounds of interest as hydrogen storage materials. The various boron hydrides are then oxidized to release their hydrogen, thereby forming a 'spent fuel' in the form of a lower boron hydride or even a boron oxide. The ultimate goal of this project is to take the oxidized boron hydrides as the spent fuel and hydrogenate them back to their original form so they can be used again as a fuel. Thus this research is essentially a boron hydride recycling project. In this report, research directed at regeneration of sodium borohydride and aminoborane is described. For sodium borohydride, electrochemical reduction of boric acid and sodium metaborate (representing spent fuel) in alkaline, aqueous solution has been investigated. Similarly to literature reports (primarily patents), a variety of cathode materials were tried in these experiments. Additionally, approaches directed at overcoming electrostatic repulsion of borate anion from the cathode, not described in the

  13. Electrochemical hydrogen Storage Systems

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Digby Macdonald

    2010-08-09

    As the global need for energy increases, scientists and engineers have found a possible solution by using hydrogen to power our world. Although hydrogen can be combusted as a fuel, it is considered an energy carrier for use in fuel cells wherein it is consumed (oxidized) without the production of greenhouse gases and produces electrical energy with high efficiency. Chemical storage of hydrogen involves release of hydrogen in a controlled manner from materials in which the hydrogen is covalently bound. Sodium borohydride and aminoborane are two materials given consideration as chemical hydrogen storage materials by the US Department of Energy. A very significant barrier to adoption of these materials as hydrogen carriers is their regeneration from 'spent fuel,' i.e., the material remaining after discharge of hydrogen. The U.S. Department of Energy (DOE) formed a Center of Excellence for Chemical Hydrogen Storage, and this work stems from that project. The DOE has identified boron hydrides as being the main compounds of interest as hydrogen storage materials. The various boron hydrides are then oxidized to release their hydrogen, thereby forming a 'spent fuel' in the form of a lower boron hydride or even a boron oxide. The ultimate goal of this project is to take the oxidized boron hydrides as the spent fuel and hydrogenate them back to their original form so they can be used again as a fuel. Thus this research is essentially a boron hydride recycling project. In this report, research directed at regeneration of sodium borohydride and aminoborane is described. For sodium borohydride, electrochemical reduction of boric acid and sodium metaborate (representing spent fuel) in alkaline, aqueous solution has been investigated. Similarly to literature reports (primarily patents), a variety of cathode materials were tried in these experiments. Additionally, approaches directed at overcoming electrostatic repulsion of borate anion from the cathode, not

  14. Synthesis of whisky lactone%威士忌内酯的合成研究

    Institute of Scientific and Technical Information of China (English)

    郭春生; 祖萌萌; 祁林; 王政; 张峻松

    2012-01-01

    With benzoyl peroxide and boric acid as catalyst,3 -methyl - 4 - oxooctanoic acid was synthesized by free radical addition reaction of valeraldehyde and crotonic acid as starting materials. Then it was reduced by sodium borohydride, and whisky lactone with cis and trans isomeric structure was obtained by intramolecular dehydration under the action of dilute sulfuric acid. The cis - trans isomers were separated by column chromatography,with eluent composed of V(petroleum ether): V(ethyl acetate) =5:1. Structure of the two targeted products were confirmed by IR,1HNMR and MS. Effect of factors on the yield such as kind of solvent, solvent amount, reaction time, dosage of sodium borohydride and dilute sulfuric acid were investigated. Optimum conditions for the reaction were found as follows:ethanol as solvent,m(ethanol): m(3 - methyl -4 -oxooctanoic acid) =3:1,reaction time 2 h at room temperature,m(sodium borohydride): m(3 -methyl -4 -oxooctanoic acid) = l:4;m(12% sulfuric acid): m(3 -methyl -4 - oxooctanoic acid) = 10: 1. Overall yield of the complete synthesis process achieves 61. 9%.%以过氧化苯甲酰和硼酸为催化剂,以戊醛和巴豆酸为起始原料经自由基加成反应合成了3-甲基-4-氧代辛酸,以硼氢化钠为还原剂和稀硫酸为脱水剂进行分子内脱水合成了顺反异构的威士忌内酯.以V(石油醚):V(乙酸乙酯)=5∶1的混合溶剂为洗脱剂,用柱层析法实现了威士忌内酯顺反异构体的分离.通过IR,1HNMR及MS确认了2种目标产物的结构.考察了溶剂、溶剂用量、反应时间、硼氢化钠用量和稀硫酸用量对目标产物收率的影响.最终的优化实验条件为:无水乙醇为溶剂,m(无水乙醇)∶m(3 -甲基-4-氧代辛酸)=3∶1,室温下反应2h,m(硼氢化钠)∶m(3-甲基-4-氧代辛酸)=1∶4,m(12%硫酸)∶m(3 -甲基-4-氧代辛酸)=10∶1,全合成的总收率为61.9%.

  15. Final Report: DE- FC36-05GO15063, Fundamental Studies of Advanced High-Capacity, Reversible Metal Hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Craig [Univ. of Hawaii, Honolulu, HI (United States); McGrady, Sean [Univ. of New Brunswick, Fredericton NB (Canada); Severa, Godwin [Univ. of Hawaii, Honolulu, HI (United States); Eliseo, Jennifer [Univ. of Hawaii, Honolulu, HI (United States); Chong, Marina [Univ. of Hawaii, Honolulu, HI (United States)

    2013-05-31

    The project was component of the US DOE, Metal Hydride Center of Excellence (MHCoE). The Sandia National Laboratory led center was established to conduct highly collaborative and multi-disciplinary applied R&D to develop new reversible hydrogen storage materials that meet or exceed DOE/FreedomCAR 2010 and 2015 system targets for hydrogen storage materials. Our approach entailed a wide variety of activities ranging from synthesis, characterization, and evaluation of new candidate hydrogen storage materials; screening of catalysts for high capacity materials requiring kinetics enhancement; development of low temperature methods for nano-confinement of hydrides and determining its effects on the kinetics and thermodynamics of hydrides; and development of novel processes for the direct re-hydrogenation of materials. These efforts have resulted in several advancements the development of hydrogen storage materials. We have greatly extended the fundamental knowledge about the highly promising hydrogen storage carrier, alane (AlH3), by carrying out the first crystal structure determinations and the first determination of the heats of dehydrogenation of β–AlH3 and γ-AlD3. A low-temperature homogenous organometallic approach to incorporation of Al and Mg based hydrides into carbon aerogels has been developed that that allows high loadings without degradation of the nano-porous scaffold. Nano-confinement was found to significantly improve the dehydrogenation kinetics but not effect the enthalpy of dehydrogenation. We conceived, characterized, and synthesized a novel class of potential hydrogen storage materials, bimetallic borohydrides. These novel compounds were found to have many favorable properties including release of significant amounts of hydrogen at moderate temperatures (75-190 º C). However, in situ IR studies in tandem with thermal gravimetric analysis have shown that about 0.5 equivalents of diborane are released during the

  16. Final Report: DE- FC36-05GO15063, Fundamental Studies of Advanced High-Capacity, Reversible Metal Hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Craig [University of Hawaii; McGrady, Sean [University of New Brunswick; Severa, Godwin [University of Hawaii; Eliseo, Jennifer [University of Hawaii; Chong, Marina [University of Hawaii

    2015-02-08

    The project was component of the US DOE, Metal Hydride Center of Excellence (MHCoE). The Sandia National Laboratory led center was established to conduct highly collaborative and multi-disciplinary applied R&D to develop new reversible hydrogen storage materials that meet or exceed DOE/FreedomCAR 2010 and 2015 system targets for hydrogen storage materials. Our approach entailed a wide variety of activities ranging from synthesis, characterization, and evaluation of new candidate hydrogen storage materials; screening of catalysts for high capacity materials requiring kinetics enhancement; development of low temperature methods for nano-confinement of hydrides and determining its effects on the kinetics and thermodynamics of hydrides; and development of novel processes for the direct re-hydrogenation of materials. These efforts have resulted in several advancements the development of hydrogen storage materials. We have greatly extended the fundamental knowledge about the highly promising hydrogen storage carrier, alane (AlH₃), by carrying out the first crystal structure determinations and the first determination of the heats of dehydrogenation of β–AlH₃ and γ-AlD₃. A low-temperature homogenous organometallic approach to incorporation of Al and Mg based hydrides into carbon aerogels has been developed that that allows high loadings without degradation of the nano-porous scaffold. Nano-confinement was found to significantly improve the dehydrogenation kinetics but not effect the enthalpy of dehydrogenation. We conceived, characterized, and synthesized a novel class of potential hydrogen storage materials, bimetallic borohydrides. These novel compounds were found to have many favorable properties including release of significant amounts of hydrogen at moderate temperatures (75-190ºC). However, in situ IR studies in tandem with thermal gravimetric analysis have shown that about 0.5 equivalents of diborane are released during the dehydrogenation making re

  17. Chemical Hydrogen Storage Using Polyhedral Borane Anions and Aluminum-Ammonia-Borane Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Hawthorne, M. Frederick; Jalisatgi, Satish S.; Safronov, Alexander V.; Lee, Han Beak; Wu, Jianguo

    2010-10-01

    Phase 1. Hydrolysis of borohydride compounds offer the potential for significant hydrogen storage capacity, but most work to date has focused on one particular anion, BH4-, which requires high pH for stability. Other borohydride compounds, in particular polyhedral borane anions offer comparable hydrogen storage capacity without requiring high pH media and their long term thermal and hydrolytic stability coupled with non-toxic nature make them a very attractive alternative to NaBH4. The University of Missouri project provided the overall program focal point for the investigation of catalytic hydrolysis of polyhedral borane anions for hydrogen release. Due to their inherent stability, a transition metal catalyst was necessary for the hydrolysis of polyhedral borane anions. Transition metal ions such as cobalt, nickel, palladium and rhodium were investigated for their catalytic activity in the hydrolysis of nido-KB11H14, closo-K2B10H10, and closo-K2B12H12. The rate of hydrolysis follows first-order kinetics with respect to the concentration of the polyhedral borane anion and surface area of the rhodium catalyst. The rate of hydrolysis depends upon a) choice of polyhedral borane anion, c) concentration of polyhedral borane anion, d) surface area of the rhodium catalyst and e) temperature of the reaction. In all cases the yield of hydrogen was 100% which corresponds to ~7 wt% of hydrogen (based on material wt%). Phase 2. The phase 2 of program at the University of Missouri was focused upon developing aluminum ammonia-boranes (Al-AB) as chemical hydrogen storage materials, specifically their synthesis and studies of their dehydrogenation. The ammonia borane molecule (AB) is a demonstrated source of chemically stored hydrogen (19.6 wt%) which meets DOE performance parameters except for its regeneration from spent AB and elemental hydrogen. The presence of an aluminum center bonded to multiple AB residues might combine the efficiency of AB dehydrogenation with an aluminum

  18. Metal interferences and their removal prior to the determination of As(T) and As(III) in acid mine waters by hydride generation atomic absorption spectrometry

    Science.gov (United States)

    McCleskey, R. Blaine; Nordstrom, D. Kirk; Ball, James W.

    2003-01-01

    Hydride generation atomic absorption spectrometry (HGAAS) is a sensitive and selective method for the determination of total arsenic (arsenic(III) plus arsenic(V)) and arsenic(III); however, it is subject to metal interferences for acid mine waters. Sodium borohydride is used to produce arsine gas, but high metal concentrations can suppress arsine production. This report investigates interferences of sixteen metal species including aluminum, antimony(III), antimony(V), cadmium, chromium(III), chromium(IV), cobalt, copper(II), iron(III), iron(II), lead, manganese, nickel, selenium(IV), selenium(VI), and zinc ranging in concentration from 0 to 1,000 milligrams per liter and offers a method for removing interfering metal cations with cation exchange resin. The degree of interference for each metal without cation-exchange on the determination of total arsenic and arsenic(III) was evaluated by spiking synthetic samples containing arsenic(III) and arsenic(V) with the potential interfering metal. Total arsenic recoveries ranged from 92 to 102 percent for all metals tested except antimony(III) and antimony(V) which suppressed arsine formation when the antimony(III)/total arsenic molar ratio exceeded 4 or the antimony(V)/total arsenic molar ratio exceeded 2. Arsenic(III) recoveries for samples spiked with aluminum, chromium(III), cobalt, iron(II), lead, manganese, nickel, selenium(VI), and zinc ranged from 84 to 107 percent over the entire concentration range tested. Low arsenic(III) recoveries occurred when the molar ratios of metals to arsenic(III) were copper greater than 120, iron(III) greater than 70, chromium(VI) greater than 2, cadmium greater than 800, antimony(III) greater than 3, antimony(V) greater than 12, or selenium(IV) greater than 1. Low recoveries result when interfering metals compete for available sodium borohydride, causing incomplete arsine production, or when the interfering metal oxidizes arsenic(III). Separation of interfering metal cations using

  19. 响应面分析优化菊粉的十二烯基琥珀酸酐改性工艺研究%Study on dodecenly succinic anhydride-modified inulin

    Institute of Scientific and Technical Information of China (English)

    李丹丹; 曹威; 周杰; 李静鹏

    2013-01-01

    为了研究菊糖的十二烯基琥珀酸酐改性工艺条件,以菊糖、硼氢化钠及十二烯基琥珀酸酐用量、反应时间、反应pH以及反应温度为影响因素,以十二烯基琥珀酸酐的取代度为考察指标,运用Plackett-Burman设计筛选出3个对菊糖的十二烯基琥珀酸酐取代度影响显著因素,即十二烯基琥珀酸酐用量、反应pH和反应时间.用响应面分析实验优化十二烯基琥珀酸菊糖酯改性工艺.十二烯基琥珀酸菊糖酯改性最优工艺:菊糖4g,硼氢化钠0.015g,十二烯基琥珀酸酐0.94g,反应时间为6.8h,反应pH8.5,反应温度35℃,菊糖的十二烯基琥珀酸酐取代度为0.0140±3.33E-05.%In order to study optimum conditions for dodecenly succinic anhydride-modified inulin,effects of the amount of inulin,the dosage of sodium borohydride and dodecenly succinic anhydride (DDSA),pH,time and temperature used on the degree of substitution of dodecenly succinic anhydride-modified inulin were investigated.Plackett-Burman was adopted to screen out the important factors,which were the dosage of dodecenly succinic anhydride,pH and time used.The optimum reaction conditions were obtained by response surface analysis..inulin 4g,sodium borohydride 0.015g,dodecenly succinic anhydride 0.94g,time 6.8h,pH8.5,temperature 35℃,and the degree of substitution of dodecenly succinic anhydride-modified inulin is 0.0140± 3.33E-05.

  20. Synthetic wastewaters treatment by electrocoagulation to remove silver nanoparticles produced by different routes.

    Science.gov (United States)

    Matias, M S; Melegari, S P; Vicentini, D S; Matias, W G; Ricordel, C; Hauchard, D

    2015-08-15

    Nanoscience is a field that has stood out in recent years. The accurate long-term health and environmental risks associated with these emerging materials are unknown. Therefore, this work investigated how to eliminate silver nanoparticles (AgNPs) from synthetic effluents by electrocoagulation (EC) due to the widespread use of this type of nanoparticle (NP) in industry and its potential inhibition power over microorganisms responsible for biological treatment in effluent treatment plants. Synthesized AgNPs were studied via four different routes by chemical reduction in aqueous solutions to simulate the chemical variations of a hypothetical industrial effluent, and efficiency conditions of the EC treatment were determined. All routes used silver nitrate as the source of silver ions, and two synthesis routes were studied with sodium citrate as a stabilizer. In route I, sodium citrate functioned simultaneously as the reducing agent and stabilizing agent, whereas route II used sodium borohydride as a reducing agent. Route III used D-glucose as the reducing agent and sodium pyrophosphate as the stabilizer; route IV used sodium pyrophosphate as the stabilizing agent and sodium borohydride as the reducing agent. The efficiency of the EC process of the different synthesized solutions was studied. For route I, after 85 min of treatment, a significant decrease in the plasmon resonance peak of the sample was observed, which reflects the efficiency in the mass reduction of AgNPs in the solution by 98.6%. In route II, after 12 min of EC, the absorbance results reached the detection limit of the measurement instrument, which indicates a minimum reduction of 99.9% of AgNPs in the solution. During the 4 min of treatment in route III, the absorbance intensities again reached the detection limit, which indicates a minimum reduction of 99.8%. In route IV, after 10 min of treatment, a minimum AgNP reduction of 99.9% was observed. Based on these results, it was possible to verify that

  1. A new method to radiolabel fulvic acids with tritium for the purpose of tracing organic matter transport at low concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Tinnacher, R.M.; Honeyman, B.D. [Environmental Science and Engineering Division, Colorado School of Mines, Golden, CO 80401, (United States); Leenheer, J.A. [U.S. Geological Survey, Denver Federal Center, Denver, CO 80225 (United States)

    2005-07-01

    Full text of publication follows: It is increasingly evident that reactive transport models for radionuclides need to include the effects of natural organic ligands, such as bacterial exudates and humic and fulvic acids. Understanding the role of such ligands in radionuclide transport requires an ability to track ligand concentrations in time and space with an analytical resolution similar to that of the target radionuclide. Unfortunately, for many systems of interest for radioactive waste disposal and performance assessment, organic ligand concentrations are quite low (e.g., mg C/ L or less). Radiolabeling organic ligands can provide a means of tracing such species at low levels and for relatively low cost. Currently-used labeling methods, however, show some limitations with respect to the chemical stability of the radiolabel, the ability to produce high label specific activities and method reproducibility. In the procedure that we will describe, fulvic acid is radiolabeled with tritium by its reduction with tritiated sodium borohydride (NaBH{sub 4}) at alkaline pH and slightly elevated temperatures. The reactant selectively reduces the carbonyl groups of aromatic and aliphatic ketones as well as quinones. This results in the formation of tritium-labeled secondary alcohols. After completion of the labeling reaction, aerobically unstable reduction products of quinones and aromatic ketones are re-oxidized under controlled experimental conditions during an aeration step. Labeling efficiency in terms of reduced reactive fulvic acid groups is in the range of 100 percent with equal weights of fulvic acid and NaBH{sub 4} in the reaction solution. This yields specific activities on the order of 50 to 100 {mu}Ci / mg fulvic acid. A quasi-chemical model of the labeling process allows the accurate prediction of the labeling efficiency based on a simplified mass action expression for the labeling reaction and the mass balance equations for fulvic acid and sodium borohydride

  2. GC-MS法测定水体中甲基汞和乙基汞%Determination of Methyl Mercury and Ethyl Mercury in Water Sample by GC-MS Method

    Institute of Scientific and Technical Information of China (English)

    刘平年; 王珍

    2013-01-01

    用巯基棉富集,四乙基硼化钠衍生,气相色谱-质谱联用法测定水体中的甲基汞和乙基汞,线性范围为10~150 ng/L,线性范围内的重复性相对标准偏差(n=10)甲基汞为4.63%,乙基汞为5.52%,方法回收率甲基汞为99.00%~103.01%,乙基汞为85.49%~97.59%。通过四乙基硼化钠衍生把甲基汞和乙基汞化转化成全烷基化合物,降低了甲基汞和乙基汞的活性,减少甲基汞和乙基汞在色谱柱上的吸附和峰拖尾的现象。方法适合实验室大批量样品的测定。%It was set up for determination of methyl mercury and ethyl mercury in water by gas chromatography-mass spectrometer with preconcentration by sulfhydryl cotton and derivation by tetraethyl sodium borohydride. The test range was 10-150 ng/L, the repeatability in linearity(n=10)was 4.63%for methyl mercury and 5.52%for ethyl mercury. The spike recovery was 99.00%-103.01%for methyl mercury and 85.49%-97.59%for ethyl mercury. The methyl mercury and ethyl mercury were transferred to full alkyl compounds by tetraethyl sodium borohydride in the method, which could reduce the absorption of methyl mercury and ethyl mercury and peak tailing in chromatograph column. The method was fit for determining samples in large number.

  3. U.S. Department of Energy Hydrogen Storage Cost Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Law, Karen; Rosenfeld, Jeffrey; Han, Vickie; Chan, Michael; Chiang, Helena; Leonard, Jon

    2013-03-11

    The overall objective of this project is to conduct cost analyses and estimate costs for on- and off-board hydrogen storage technologies under development by the U.S. Department of Energy (DOE) on a consistent, independent basis. This can help guide DOE and stakeholders toward the most-promising research, development and commercialization pathways for hydrogen-fueled vehicles. A specific focus of the project is to estimate hydrogen storage system cost in high-volume production scenarios relative to the DOE target that was in place when this cost analysis was initiated. This report and its results reflect work conducted by TIAX between 2004 and 2012, including recent refinements and updates. The report provides a system-level evaluation of costs and performance for four broad categories of on-board hydrogen storage: (1) reversible on-board metal hydrides (e.g., magnesium hydride, sodium alanate); (2) regenerable off-board chemical hydrogen storage materials(e.g., hydrolysis of sodium borohydride, ammonia borane); (3) high surface area sorbents (e.g., carbon-based materials); and 4) advanced physical storage (e.g., 700-bar compressed, cryo-compressed and liquid hydrogen). Additionally, the off-board efficiency and processing costs of several hydrogen storage systems were evaluated and reported, including: (1) liquid carrier, (2) sodium borohydride, (3) ammonia borane, and (4) magnesium hydride. TIAX applied a bottom-up costing methodology customized to analyze and quantify the processes used in the manufacture of hydrogen storage systems. This methodology, used in conjunction with ® software and other tools, developed costs for all major tank components, balance-of-tank, tank assembly, and system assembly. Based on this methodology, the figure below shows the projected on-board high-volume factory costs of the various analyzed hydrogen storage systems, as designed. Reductions in the key cost drivers may bring hydrogen storage system costs closer to this DOE target

  4. Synthesis of tert-Butyl-4-Methyl-3-Oxopiperidine-1-Carboxylate%1-叔丁羰基-4-甲基-3-哌啶酮的合成研究

    Institute of Scientific and Technical Information of China (English)

    郝宝玉; 张维汉; 耿秀丽; 赵倩; 陈新志

    2011-01-01

    1-叔丁羰基-4-甲基-3-哌啶酮是合成新型蛋白酪氨酸激酶Jak3抑制剂CP-690550的重要中间体,今以廉价易得的3-羟基-4-甲基吡啶和氯苄为原料,经过SN2取代反应,再经硼氢化还原生成N-苄基-3-羟基-4-甲基哌啶.过程中考察了溶剂对实验的影响,确定最佳溶剂为3.0 mol·L-1 NaOH水溶液,后经Jones氧化,Pd/C催化脱苄及酰基化反应,得到目标产物1-叔丁羰基-4-甲基-3-哌啶酮,总收率达80.2%.该工艺较现有工艺具有反应原料易得,工艺简单,收率高,较易工业化等优点.%tert-Butyl 4-methyl-3-oxopiperidine-l-carboxylate is an important intermediate in the synthesis of the novel protein tyrosine kinase Jak3 inhibitor-CP-690550. In this article, an efficient approach to the synthesis of this interesting compound was proposed. The proposed synthesis process consists of a series of steps: starting from the easy available reagent 4-methylpyridinium, going through the SN2 substitution with benzyl chloride to offer l-benzyl-3-hydroxy-4-methylpyridium chloride with high yield, and then defining the suitable solvent species and its reasonable concentration for the borohydride reduction with sodium borohydride to provide N-benzyl-3-hydroxy- 4- methylpiperidine, consequently, oxidation by Jones reagent under mild temperature to give N-benzyl-3-oxo-4-methylpiperdine, and at last, debenzylation with Pd/C catalyst and acylation to obtain the target product /erf-butyl 4-methyl-3-oxopiperidine-l-carboxylate. The total yield can reach 80.2% by using the proposed method. Compared with the existing process, the proposed method has the advantages of easily obtained raw materials, simple in operation and suitable for industrial scale-up.

  5. Microstructure and magnetic properties of MFe{sub 2}O{sub 4} (M = Co, Ni, and Mn) ferrite nanocrystals prepared using colloid mill and hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wei, E-mail: wangwei@mail.buct.edu.cn; Ding, Zui; Zhao, Xiruo [State Key Laboratory of Chemical Resource Engineering and School of Science, Beijing University of Chemical Technology, Beijing 100029 (China); Beijing Key Laboratory of Environmentally Harmful Chemical Analysis, Beijing University of Chemical Technology, Beijing 100029 (China); Wu, Sizhu [State Key Laboratory of Organic–Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China); Li, Feng [State Key Laboratory of Chemical Resource Engineering and School of Science, Beijing University of Chemical Technology, Beijing 100029 (China); Yue, Ming [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100022 (China); Liu, J. Ping [Department of Physics, University of Texas at Arlington, Arlington, Texas 76019 (United States)

    2015-05-07

    Three kinds of spinel ferrite nanocrystals, MFe{sub 2}O{sub 4} (M = Co, Ni, and Mn), are synthesized using colloid mill and hydrothermal method. During the synthesis process, a rapid mixing and reduction of cations with sodium borohydride (NaBH{sub 4}) take place in a colloid mill then through a hydrothermal reaction, a slow oxidation and structural transformation of the spinel ferrite nanocrystals occur. The phase purity and crystal lattice parameters are estimated by X-ray diffraction studies. Scanning electron microscopy and transmission electron microscopy images show the morphology and particle size of the as-synthesized ferrite nanocrystals. Raman spectrum reveals active phonon modes at room temperature, and a shifting of the modes implies cation redistribution in the tetrahedral and octahedral sites. Magnetic measurements show that all the obtained samples exhibit higher saturation magnetization (M{sub s}). Meanwhile, experiments demonstrate that the hydrothermal reaction time has significant effects on microstructure, morphologies, and magnetic properties of the as-synthesized ferrite nanocrystals.

  6. Synthesis, characterization and fabrication of copper nanoparticles in N-isopropylacrylamide based co-polymer microgels for degradation of p-nitrophenol

    Directory of Open Access Journals (Sweden)

    Farooqi Zahoor H.

    2015-03-01

    Full Text Available Poly(N-isopropylacrylamide-co-acrylic acid [P(NIPAM-co-AAc] microgels were synthesized by precipitation polymerization. Copper nanoparticles were successfully fabricated inside the microgels by in-situ reduction of copper ions in an aqueous medium. The microgels were characterized by Fourier Transform Infrared Spectroscopy (FT-IR and Dynamic Light Scattering (DLS. Hydrodynamic radius of P(NIPAM-co-AAc microgel particles increased with an increase in pH in aqueous medium at 25 °C. Copper-poly(N-isopropylacrylamide-co-acrylic acid [Cu-P(NIPAM-co-AAc] hybrid microgels were used as a catalyst for the reduction of 4-nitrophenol (4-NP. Effect of temperature, concentration of sodium borohydride (NaBH4 and catalyst dosage on the value of apparent rate constant (kapp for catalytic reduction of 4-NP in the presence of Cu-P(NIPAM-co-AAc hybrid microgels were investigated by UV-Vis spectrophotometry. It was found that the value of kapp for catalytic reduction of 4-NP in the presence of Cu-P(NIPAM-co-AAc hybrid microgel catalyst increased with an increase in catalyst dosage, temperature and concentration of NaBH4 in aqueous medium. The results were discussed in terms of diffusion of reactants towards catalyst surface and swelling-deswelling of hybrid microgels.

  7. Synthesis, characterization, optical and antimicrobial studies of polyvinyl alcohol-silver nanocomposites

    Science.gov (United States)

    Mahmoud, K. H.

    2015-03-01

    Silver nanoparticles (Ag NPs) were synthesized by chemical reduction of silver salt (AgNO3) through sodium borohydride. The characteristic surface plasmon resonance band located at around 400 nm in the UV-Visible absorption spectrum confirmed the formation of Ag nanoparticles. Polyvinyl alcohol-silver (PVA-Ag) nanocomposite films were prepared by the casting technique. The morphology and interaction of PVA with Ag NPs were examined by transmission electron microscopy and FTIR spectroscopy. Optical studies show that PVA exhibited indirect allowed optical transition with optical energy gap of 4.8 eV, which reduced to 4.45 eV under addition of Ag NPs. Optical parameters such as refractive index, complex dielectric constant and their dispersions have been analyzed using Wemple and DiDomenco model. Color properties of the nanocomposites are discussed in the framework of CIE L∗u∗v∗ color space. The antimicrobial activity of the nanocomposite samples was tested against Gram positive bacteria (Staphylococcus aureus NCTC 7447 &Bacillus subtillis NCIB 3610), Gram negative bacteria (Escherichia coli, NTC10416 &Pseudomonas aeruginosa NCIB 9016) and fungi (Aspergillus niger Ferm - BAM C-21) using the agar diffusion technique. The antimicrobial study showed that PVA has moderate antibacterial activity against B. subtillis and the 0.04 wt% Ag NPs composite sample effect was strong against S. aureus.

  8. 稳定分散的纳米银溶胶的制备及其表征%Preparation and Characterization of Stable Dispersive Colloidal Silver Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    王悦辉; 周济; 王婷

    2007-01-01

    Stable aqueous dispersive colloidal Ag nanoparticles were prepared by reducing silver nitrate with sodium borohydride in the presence of 3-mercaptopropionic acid. The formation process of the Ag nanoparticles was investigated by UV-Visible spectroscopy and transmission electron microscopy. The results show that the spherical and rodlike particles and aggregates are formed in the initial stage of the reaction, then the rodlike particles and aggregates are gradually decomposed into small Spherical particles, and the final obtained Ag nanoparticles with an average size of 8 nm are in uniform shapes and narrow size distribution, and the colloid remains stable for more than one month, which makes it convenient for use in practice. The presence of capping agent plays an extra role over nanoparticles stabilization and morphology.The presence of capping agent on the surface of Ag nanoparticle is confirmed by the X-ray photoelectron spectroscopy. It is found that Ag nanoparticles are negatively charged in alkaline condition, whereas they are positively charged in acid condition. Electrosteric effect is responsible for their long-term stability.

  9. Micro space power system using MEMS fuel cell for nano-satellites

    Science.gov (United States)

    Lee, Jongkwang; Kim, Taegyu

    2014-08-01

    A micro space power system using micro fuel cell was developed for nano-satellites. The power system was fabricated using microelectromechanical system (MEMS) fabrication technologies. Polymer electrolyte membrane (PEM) fuel cell was selected in consideration of space environment. Sodium borohydride (NaBH4) was selected as a hydrogen source while hydrogen peroxide (H2O2) was selected as an oxygen source. The power system consists of a micro fuel cell, micro-reactor, micro-pump, and fuel cartridges. The micro fuel cell was fabricated on a light-weight and corrosion-resistant glass plates. The micro-reactor was used to generate hydrogen from NaBH4 alkaline solution via a catalytic hydrolysis reaction. All components such as micro-pump, fuel cartridges, and auxiliary battery were integrated for a complete power system. The storability of NaBH4 solution was evaluated at -25 °C and the performance of the micro power system was measured at various operating conditions. The power output of micro power system reasonably followed up the given electric load conditions.

  10. Preparation and Characterization of Chitosan-Humic Acid-Zerovalent Iron Nanocomposite for Nitrate Reduction in Water

    Directory of Open Access Journals (Sweden)

    Caroline Avosuahi Akinremi

    2016-01-01

    Full Text Available A new zerovalent iron chitosan-humic acid nanocomposite was prepared and tested for nitrate ion reduction in water. Humic acid was used for intramolecular cross-linking of the chitosan linear chains to increase the active sites on the chitosan biopolymer and then further used as a stabilizer to synthesize zerovalent iron nanoparticles by the reduction of iron (II chloride with sodium borohydride. Characterization of the products was carried out using infrared spectroscopy, scanning electron microscope, energy dispersive X-ray, and X-ray diffractometer. Batch experiments were conducted for the reduction of nitrate in water using different concentrations of the products in different concentrations of nitrate ion and at different contact time. The adsorption equilibrium data for the nitrate solution gave a favorable adsorption according to the Langmuir equation. Varying the nanocomposite-to-nitrate ion ratio generally led to faster nitrate reduction, with the pseudofirst-order rate constant for the adsorption increasing with increase in nanocomposite-to-nitrate ion ratio. Nitrate removal efficiency of zerovalent iron chitosan-humic acid nanocomposite was further confirmed using real water samples obtained from drainage waste and river with an initial nitrate concentration of 18.00±0.01 and 12.00±0.12 ppm, respectively. The reduction of nitrate in water using the nanocomposite was concluded to be highly effective.

  11. The hydrogenation of benzene ring catalyzed by supported ruthenium complex using 2-viny1 pyridine copolymer beads as ligands%共聚物配体钌配合物的苯环催化加氢性能研究

    Institute of Scientific and Technical Information of China (English)

    石秀丽

    2006-01-01

    采用XPS等分析手段证实了2-乙烯基吡啶和甲基丙烯酸乙二醇双醋的交联共聚物小球可作为配体与钌形成配合物,该配合经硼氢化钠还原后生成加氢催化剂PVMRu*,其对苯环(苯、苯酚)催化剂加氢的性能良好,所生成产物的选择性高.实验结果表明:温度、压力及搅拌速度的提高均有利于提高反应的活性.%The hydrogenation of benzene to cyclohexane over 2-vinyl pyridine and 1,2-(methacrylate) glycol cross-linked copolymer beads were used as ligands to form the corresponding ruthenium complex, the subsequent reduction of which with sodium borohydride displayed good catalytic properties in hydrogenation of benzene ring . The experimental results showed that the catalytic activity can be enhanced with the increase in temperature , pressure and stirring rate of the reaction system.

  12. Impact of reaction parameters on the chemical profile of 3,4-methylenedioxymethamphetamine synthesized via reductive amination: target analysis based on GC-qMS compared to non-targeted analysis based on GC×GC-TOF-MS.

    Science.gov (United States)

    Schäffer, M; Dieckmann, S; Pütz, M; Kohles, T; Pyell, U; Zimmermann, R

    2013-12-10

    The most common clandestine manufacturing procedure for the ecstasy derivative 3,4-methylenedioxymethamphetamine (MDMA), is the reductive amination of piperonylmethylketone (PMK) via platinum(IV) oxide/hydrogen. Deviations of the reaction conditions during the synthesis may result in different chemical profiles of the products. The chemical analysis of these profiles is an important objective for forensic drug intelligence. In this work we studied the impact of a systematic variation of the hydrogenation time, the reaction temperature and the precursor batch on the resulting organic chemical profiles of the MDMA bases and MDMA hydrochlorides. Target analysis was based on a gas chromatography mass spectrometry (GC-MS) method which was harmonized during the European project CHAMP.(2) In addition, samples were analyzed by comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOFMS) and subjected to non-targeted data analysis for a comprehensive analysis of the complete profiles. The reaction temperature, followed by the used precursor batch, revealed the highest impact on the chemical profile. The effect on individual impurity compounds is discussed in detail. With respect to the interpretation of the data, the profiles were compared to the profiles of MDMA samples obtained by reductive amination using sodium borohydride ("cold method") and aluminium/mercury amalgam as alternative reducing agents. Non-targeted analysis revealed that the discrimination according to the synthetic route and the batch of precursor used for the synthesis strongly depends on the selected target compounds. PMID:24314521

  13. Fast and facile preparation of CTAB based gels and their applications in Au and Ag nanoparticles synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Upadhyay, Ravi Kant, E-mail: rkupadhyay85@gmail.com [Department of Chemistry, School of Natural Sciences, Shiv Nadar University, Gautam Budh Nagar, 201314 Uttar Pradesh (India); Soin, Navneet, E-mail: n.soin@bolton.ac.uk [Knowledge Centre for Materials Chemistry (KCMC), Institute for Materials Research and Innovation (IMRI), University of Bolton, Deane Road, Bolton BL3 5AB (United Kingdom); Saha, Susmita, E-mail: ssaha@bose.res.in [Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098 (India); Barman, Anjan, E-mail: abarman@bose.res.in [Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098 (India); Sinha Roy, Susanta, E-mail: susanta.roy@snu.edu.in [Department of Physics, School of Natural Sciences, Shiv Nadar University, Gautam Budh Nagar, 201314 Uttar Pradesh (India)

    2015-04-15

    We have demonstrated that the gel-like mesophase of Cetyltrimethylammonium bromide (CTAB) can be synthesized by judicial adjustment of water to surfactant molar ratio (W{sub 0}), without using any additional salts, gelating agents or co-surfactants. Gel formation was found to be highly dependent on the water to surfactant molar ratio (W{sub 0}), with the lowest value of W{sub 0} (41.5) resulting in rapid gel formation. Environmental scanning electron microscope (ESEM) analysis revealed that the gel was comprised of interconnected cylindrical structures. The presence of hydrogen bonding in the gel-like mesophase was confirmed by Fourier Transform Infrared spectroscopy (FTIR) analysis. Rheology measurements revealed that all the gel samples were highly viscoelastic in nature. Furthermore, Au and Ag containing CTAB gels were explored as precursors for the preparation of spherical Gold (Au) and Silver (Ag) nanoparticles using Sodium borohydride (NaBH{sub 4}) as reducing agent. The effects of NaBH{sub 4} concentration on the particle size and morphology of the Au and Ag nanoparticles have also been studied. - Highlights: • A facile synthesis of CTAB based gel-like mesophase is reported. • CTAB gels were obtained by adjusting water to surfactant molar ratio (W{sub 0}). • FTIR analysis revealed that hydrogen bonding plays a key role in gel formation. • Au, Ag nanoparticles were synthesized by using CTAB gel and NaBH{sub 4}.

  14. Preparation of Silver Nanostructures from Bicontinuous Microemulsions

    Directory of Open Access Journals (Sweden)

    M. A. Pedroza-Toscano

    2012-01-01

    Full Text Available Precipitation of silver nanoparticles at 70°C was carried out by dosing a 1.3 M sodium borohydride aqueous solution over bicontinuous microemulsions formed with a mixture of sodium bis(2-ethylhexyl sulfosuccinate (AOT and sodium dodecylsulfate (SDS as surfactants, a 0.5 M silver nitrate aqueous solution, and toluene. Weight ratios of 2.5/1 and 3/1 AOT/SDS were used in the precipitation reactions. Silver nanoparticles were characterized by transmission electronic microscopy, X-ray diffraction, and atomic absorption spectroscopy. A mixture of isolated spheroidal nanoparticles (≈15 wt.% with an average diameter around 10 nm and wormlike structures (≈85 wt.% with an average length close to 480 nm and an average diameter ca. 40 nm was obtained, regardless of the AOT/SDS ratio. Higher yields were obtained compared with those reported when reverse microemulsions were employed. Formation of wormlike structures was ascribed to one-dimensional aggregation of crystal and particles within the channels of bicontinuous microemulsions, which performed as templates.

  15. Colorimetric humidity sensor based on liquid composite materials for the monitoring of food and pharmaceuticals.

    Science.gov (United States)

    Bridgeman, Devon; Corral, Javier; Quach, Ashley; Xian, Xiaojun; Forzani, Erica

    2014-09-01

    Using supported ionic-liquid membrane (SILM)-inspired methodologies, we have synthesized, characterized, and developed a humidity sensor by coating a liquid composite material onto a hygroscopic, porous substrate. Similar to pH paper, the sensor responds to the environment's relative humidity and changes color accordingly. The humidity indicator is prepared by casting a few microliters of low-toxicity reagents on a nontoxic substrate. The sensing material is a newly synthesized liquid composite that comprises a hygroscopic medium for environmental humidity capture and a color indicator that translates the humidity level into a distinct color change. Sodium borohydride was used to form a liquid composite medium, and DenimBlu30 dye was used as a redox indicator. The liquid composite medium provides a hygroscopic response to the relative humidity, and DenimBlu30 translates the chemical changes into a visual change from yellow to blue. The borate-redox dye-based humidity sensor was prepared, and then Fourier transform infrared spectroscopy, differential scanning calorimetry, and image analysis methods were used to characterize the chemical composition, optimize synthesis, and gain insight into the sensor reactivity. Test results indicated that this new sensing material can detect relative humidity in the range of 5-100% in an irreversible manner with good reproducibility and high accuracy. The sensor is a low-cost, highly sensitive, easy-to-use humidity indicator. More importantly, it can be easily packaged with products to monitor humidity levels in pharmaceutical and food packaging. PMID:25141132

  16. Synthesis and characterization of silver/talc nanocomposites using the wet chemical reduction method.

    Science.gov (United States)

    Shameli, Kamyar; Ahmad, Mansor Bin; Yunus, Wan Zin Wan; Ibrahim, Nor Azowa; Darroudi, Majid

    2010-10-05

    In this study, silver nanoparticles (Ag-NPs) were synthesized using the wet chemical reduction method on the external surface layer of talc mineral as a solid support. Silver nitrate and sodium borohydride were used as the silver precursor and reducing agent in talc. The talc was suspended in aqueous AgNO(3) solution. After the absorption of Ag(+) on the surface, the ions were reduced with NaBH(4). The interlamellar space limits were without many changes (d(s) = 9.34-9.19 A(º)); therefore, Ag-NPs formed on the exterior surface of talc, with d(ave) = 7.60-13.11 nm in diameter. The properties of Ag/talc nanocomposites (Ag/talc-NCs) and the diameters of the Ag-NPs prepared in this way depended on the primary AgNO(3) concentration. The prepared Ag-NPs were characterized by ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Fourier transform infrared. These Ag/talc-NCs may have potential applications in the chemical and biological industries.

  17. Synthesis and characterization of silver/talc nanocomposites using the wet chemical reduction method

    Directory of Open Access Journals (Sweden)

    Kamyar Shameli

    2010-09-01

    Full Text Available Kamyar Shameli1, Mansor Bin Ahmad1, Wan Zin Wan Yunus1, Nor Azowa Ibrahim1, Majid Darroudi21Department of Chemistry, Faculty of Science, 2Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, Selangor, MalaysiaAbstract: In this study, silver nanoparticles (Ag-NPs were synthesized using the wet chemical reduction method on the external surface layer of talc mineral as a solid support. Silver nitrate and sodium borohydride were used as the silver precursor and reducing agent in talc. The talc was suspended in aqueous AgNO3 solution. After the absorption of Ag+ on the surface, the ions were reduced with NaBH4. The interlamellar space limits were without many changes (ds = 9.34–9.19 Aº; therefore, Ag-NPs formed on the exterior surface of talc, with dave = 7.60–13.11 nm in diameter. The properties of Ag/talc nanocomposites (Ag/talc-NCs and the diameters of the Ag-NPs prepared in this way depended on the primary AgNO3 concentration. The prepared Ag-NPs were characterized by ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Fourier transform infrared. These Ag/talc-NCs may have potential applications in the chemical and biological industries.Keywords: nanocomposites, silver nanoparticles, talc, powder X-ray diffraction, scanning electron microscopy

  18. Size control of semimetal bismuth nanoparticles and the UV-visible and IR absorption spectra.

    Science.gov (United States)

    Wang, Y W; Hong, Byung Hee; Kim, Kwang S

    2005-04-21

    We introduced a simple chemical method to synthesize semimetal bismuth nanoparticles in N,N-dimethylformamide (DMF) by reducing Bi(3+) with sodium borohydride (NaBH(4)) in the presence of poly(vinylpyrroldone) (PVP) at room temperature. The size and dispersibility of Bi nanoparticles can be easily controlled by changing the synthetic conditions such as the molar ratio of PVP to BiCl(3) and the concentration of BiCl(3). The UV-visible absorption spectra of Bi nanoparticles of different diameters are systematically studied. The surface plasmon peaks broaden with the increasing molar ratio of PVP to BiCl(3) as the size of bismuth nanoparticles decreases. Infrared (IR) spectra of the complexes with different molar ratios of PVP/BiCl(3) show a strong interaction between the carboxyl oxygen (C=O) of PVP and Bi(3+) ion and a weak interaction between the carboxyl oxygen (C=O) of PVP and the Bi atom in nanoparticles. This indicates that PVP serves as an effective capping ligand, which prevents the nanoparticles from aggregation.

  19. 3,3,5-Trimethylcyclohexanols and derived esters: green synthetic procedures, odour evaluation and in vitro skin cytotoxicity assays.

    Science.gov (United States)

    Gambaro, R; Villa, C; Baldassari, S; Mariani, E; Parodi, A; Bassi, A M

    2006-12-01

    The alcohols 3,3,5-trimethylcyclohexanols (cis, trans epimers, cosmetic fragrance) and some derived esters, potential and well-known actives in the cosmetic field, such as Homosalate, were synthesized using fast solvent-free methodologies with the aim of renewing and simplifying the conventional procedures. The alcohols were prepared by reduction of 3,3,5-trimethylcyclohexanone (dihydroisophorone) with sodium borohydride/alumina in solid state. The esters from propanoic, butanoic, octanoic, 10-undecenoic, cyclopropanecarboxylic, mandelic and salicylic acids were synthesized with microwave-mediated solvent-free procedures under acidic and basic catalysis. Several experiments were carried out to study advantages and limits of the selected methodologies and the results are reported. Microwave irradiation was carried out using a scientific monomode reactor. In order to evaluate the cosmetic interest of the studied compounds, the sweet-scented substances were submitted to an odour evaluation test; the most promising fragrances and the ester from 10-undecenoic acid, as an example of lipophilic derivatives, were tested to assess their in vitro skin toxicity. Résumé PMID:18489288

  20. DDT degradation efficiency and ecotoxicological effects of two types of nano-sized zero-valent iron (nZVI) in water and soil.

    Science.gov (United States)

    El-Temsah, Yehia S; Sevcu, Alena; Bobcikova, Katerina; Cernik, Miroslav; Joner, Erik J

    2016-02-01

    Nano-scale zero-valent iron (nZVI) has been conceived for cost-efficient degradation of chlorinated pollutants in soil as an alternative to e.g permeable reactive barriers or excavation. Little is however known about its efficiency in degradation of the ubiquitous environmental pollutant DDT and its secondary effects on organisms. Here, two types of nZVI (type B made using precipitation with borohydride, and type T produced by gas phase reduction of iron oxides under H2) were compared for efficiency in degradation of DDT in water and in a historically (>45 years) contaminated soil (24 mg kg(-1) DDT). Further, the ecotoxicity of soil and water was tested on plants (barley and flax), earthworms (Eisenia fetida), ostracods (Heterocypris incongruens), and bacteria (Escherichia coli). Both types of nZVI effectively degraded DDT in water, but showed lower degradation of aged DDT in soil. Both types of nZVI had negative impact on the tested organisms, with nZVI-T giving least adverse effects. Negative effects were mostly due to oxidation of nZVI, resulting in O2 consumption and excess Fe(II) in water and soil. PMID:26598990

  1. Electrical and Thermal Behavior of Copper-Epoxy Nanocomposites Prepared via Aqueous to Organic Phase Transfer Technique

    Directory of Open Access Journals (Sweden)

    N. H. Mohd Hirmizi

    2012-01-01

    Full Text Available The preparation, electrical, and thermal behaviors of copper-epoxy nanocomposites are described. Cetyltrimethylammonium bromide- (CTAB- stabilized copper (Cu particles were synthesized via phase transfer technique. Isopropanol (IPA, sodium borohydride (NaBH4, and toluene solution of diglycidyl ether of bisphenol A (DGEBA were used as transferring, reducing agent, and the organic phase, respectively. The UV-Vis absorbance spectra of all the sols prepared indicate that the presence of Cu particles with the particles transfer efficiency is ≥97%. The amount, size, and size distribution of particles in the organosol were dependent on the content of organic solute in the organosol. The composites were obtained upon drying the organosols and these were then subjected to further studies on the curing, thermal, and electrical characteristic. The presence of Cu fillers does not significantly affect the completeness of the composite curing process and only slightly reduce the thermal stability of the composites that is >300°C. The highest conductivity value of the composites obtained is 3.06×10-2 S cm-1.

  2. Preparation of Chitosan/Polystyrene Sulfonate Multilayered Composite Metal Nanoparticles and Its Application.

    Science.gov (United States)

    Xiong, Fangxin; Chen, Chunxiao; Liu, Shantang

    2016-06-01

    Metal-Chitosan (CTS) composite was first synthesized through the metal composition of chitosan (CTS) and metal ions. The formed composite was alternately deposited on the base with sodium polystyrene sulfonate (PSS) through a layer-by-layer self-assembling technique, followed by an in situ reduction by sodium borohydride to produce a polyelectrolyte nanocomposite thin film containing metal nanoparticles. Assembly, surface morphology and electrochemical properties of the composite membrane were analyzed by UV-visible absorption spectroscopy (UV-vis), atomic force microscopy (AFM) and cyclic voltammetry (CV). The UV-Vis results indicated that the absorbance of the multilayer film at the characteristic absorption peak increased as the membrane bilayers increased, in a good linear relationship, which demonstrated that the multilayer film was uniformly assembled on the base. AFM images showed that the surface of the multilayer thin-film composite had some degree of roughness and metal nanoparticles of 10-20 nm in size were generated on the membrane. The CV results indicated that the metal nanocomposite film had excellent electrocatalytic activity to glucose and had a potential for applications in electrochemical sensors.

  3. Controllable Synthesis and Tunable Photocatalytic Properties of Ti(3+)-doped TiO2.

    Science.gov (United States)

    Ren, Ren; Wen, Zhenhai; Cui, Shumao; Hou, Yang; Guo, Xiaoru; Chen, Junhong

    2015-01-01

    Photocatalysts show great potential in environmental remediation and water splitting using either artificial or natural light. Titanium dioxide (TiO2)-based photocatalysts are studied most frequently because they are stable, non-toxic, readily available, and highly efficient. However, the relatively wide band gap of TiO2 significantly limits its use under visible light or solar light. We herein report a facile route for controllable synthesis of Ti(3+)-doped TiO2 with tunable photocatalytic properties using a hydrothermal method with varying amounts of reductant, i.e., sodium borohydride (NaBH4). The resulting TiO2 showed color changes from light yellow, light grey, to dark grey with the increasing amount of NaBH4. The present method can controllably and effectively reduce Ti(4+) on the surface of TiO2 and induce partial transformation of anatase TiO2 to rutile TiO2, with the evolution of nanoparticles into hierarchical structures attributable to a high pressure and strong alkali environment in the synthesis atmosphere; in this way, the photocatalytic activity of Ti(3+)-doped TiO2 under visible-light can be tuned. The as-developed strategy may open up a new avenue for designing and functionalizing TiO2 materials for enhancing visible light absorption, narrowing band gap, and improving photocatalytic activity. PMID:26044406

  4. Controllable Synthesis and Tunable Photocatalytic Properties of Ti3+-doped TiO2

    Science.gov (United States)

    Ren, Ren; Wen, Zhenhai; Cui, Shumao; Hou, Yang; Guo, Xiaoru; Chen, Junhong

    2015-01-01

    Photocatalysts show great potential in environmental remediation and water splitting using either artificial or natural light. Titanium dioxide (TiO2)-based photocatalysts are studied most frequently because they are stable, non-toxic, readily available, and highly efficient. However, the relatively wide band gap of TiO2 significantly limits its use under visible light or solar light. We herein report a facile route for controllable synthesis of Ti3+-doped TiO2 with tunable photocatalytic properties using a hydrothermal method with varying amounts of reductant, i.e., sodium borohydride (NaBH4). The resulting TiO2 showed color changes from light yellow, light grey, to dark grey with the increasing amount of NaBH4. The present method can controllably and effectively reduce Ti4+ on the surface of TiO2 and induce partial transformation of anatase TiO2 to rutile TiO2, with the evolution of nanoparticles into hierarchical structures attributable to a high pressure and strong alkali environment in the synthesis atmosphere; in this way, the photocatalytic activity of Ti3+-doped TiO2 under visible-light can be tuned. The as-developed strategy may open up a new avenue for designing and functionalizing TiO2 materials for enhancing visible light absorption, narrowing band gap, and improving photocatalytic activity. PMID:26044406

  5. Colorimetric kinetic determination of potassium ions based on the use of a specific aptamer and catalytically active gold nanoparticles

    International Nuclear Information System (INIS)

    We describe a simple, highly sensitive, and selective colorimetric kinetic assay for the determination of potassium(I) by exploiting the specific recognition capability of an appropriate aptamer and catalytic signal amplification by gold nanoparticles (AuNPs). Amplification is based on the reduction of 4-nitrophenol by borohydride which is catalyzed by AuNPs. This leads to a color change of the solution from yellow to colorless, and the color change can be recognized with bare eyes or via photometry. The K(I)-selective aptamer is placed on the AuNPs and forms a tightly bound G-quadruplex with K(I) which partially masks the surface of the AuNPs and prevents 4-nitrophenol to be reduced at the catalytically active surface of the AuNPs. Hence, the rate of decoloration is retarded. The assay displays high selectivity for K(I) over other cations, has a linear response in the 0.1 nM to 10 μM concentration range, and a detection limit as low as 0.06 nM. In addition, these findings pave the way to novel analytical methods based on the use of gold nanoparticle-catalyzed chemical reactions. (author)

  6. Catalytic reductive dechlorination of p-chlorophenol in water using Ni/Fe nanoscale particles

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei-hua; QUAN Xie; ZHANG Zhuo-yong

    2007-01-01

    Nanoscale bimetallic Ni/Fe particles were synthesized from the reaction of sodium borohydride (NaBH4)with reduction of Ni2+and Fe2+ in aqueous solution.The obtained Ni/Fe particles were characterized by TEM(transmission electron microscope),XRD(X-ray diffractometer),and N2-BET The dechlorination activity of the Ni/Fe was investigated using P-chlorophenol (p-CP)as a pmbe agent.Results demonstrated that the nanoscale Ni/Fe could effectively dechlorinate P-CP at relatively low metal to solution ratio of 0.4 g/L (Ni 5 wt%).The target with initial concentration of P-CP O.625 mmol/L was dechlorinted completely in 60 min under ambient temperature and pressure.Factors affecting dechlorination efficiency,including reaction temperature,pH,Ni loading percentage over Fe,and metal to solution ratio.were investigated.The possible mechanism of dechlorination of P-CP was proposed and discussed.The pseudo-first-order reaction took place on the surface of the Ni/Fe bimetallic particles,and the activation energy of the dechlorination reaction was determined to be 21.2 kJ/mol at the temperature rang of 287-313 K.

  7. A Comparative Study of the Adsorption of Methylene Blue onto Synthesized Nanoscale Zero-Valent Iron-Bamboo and Manganese-Bamboo Composites

    Directory of Open Access Journals (Sweden)

    Solomon E. Shaibu

    2014-06-01

    Full Text Available In this study, bamboo impregnated with nanoscale zero-valent iron (nZVI and nanoscale manganese (nMn were prepared by the aqueous phase borohydride reduction method and characterized using scanning electron microscopy (SEM, Fourier transform infrared spectroscopy (FTIR and PIXE analysis. The synthesized nMn-bamboo and nZVI-bamboo composites were subsequently applied to the sorption of methylene blue (MB dye from aqueous solution. The adsorption of MB dye was investigated under various experimental conditions such as pH, contact time, initial concentration of MB dye and adsorbent dosage. The results showed that the synthesized nZVI-bamboo composite was more effective than nMn-bamboo composite in terms of higher MB dye adsorption capacity of 322.5 mg/g compared to 263.5 mg/g of nMn-bamboo composite. At a concentration of 140 mg/L MB dye, 0.02 g of nZVI-bamboo and nMn-bamboo composites resulted in 79.6% and 78.3% removal, respectively, at 165 rpm, contact time of 120 min and at a solution pH of 7.6. The equilibrium data was best represented by Freundlich isotherm model and the pseudo-second order kinetic model better explained the kinetic data for both nZVI-bamboo and nMn-bamboo composites.

  8. Synthesis and Crystal Structure of(3S,4R,Z)-3,6-dimethyl-2-(3-methylbut-2-enylidene)-2,3,3a,4,7,7a-hexahydrobenzofuran-3,4-diol

    Institute of Scientific and Technical Information of China (English)

    CHEN Lei; FANG Hu-Biao; HUANG Nian-Yu; WANG Jun-Zhi; ZOU Kun

    2011-01-01

    The title compound of(3S,4R,Z)-3,6-dimethyl-2-(3-methylbut-2-enylidene)-2,3,3a,4,7,7a-hexahydrobenzofuran-3,4-diol,C15H22O3,as a potential gastric cytoprotective agent has been synthesized by the reduction of bisabolangelone in methanol with sodium borohydride.The title compound was characterized by IR and NMR spectra.Meanwhile,the crystal was obtained and determined by X-ray single-crystal diffraction.Crystal data:monoclinic system,space group P21 with a = 6.0692(12),b = 8.9954(18),c = 13.182(3) ,β = 92.59(3)°,V = 718.9(2) 3,Z = 2,F(000) = 272,Dc = 1.156 g/cm3,μ = 0.633 mm-1,R = 0.0362 and wR = 0.1051 for 9490 independent reflections(Rint = 0.0172) and 2461 observed reflections(I 2σ(I)).Intermolecular O-H…O interactions link the molecules into one-dimensional infinite chains running along the b axis,which contributes to the stability of the crystal structure.

  9. Micro reactor integrated μ-PEM fuel cell system: a feed connector and flow field free approach

    International Nuclear Information System (INIS)

    A system level microreactor concept for hydrogen generation with Sodium Borohydride (NaBH4) is demonstrated. The uniqueness of the system is the transport and distribution feature of fuel (hydrogen) to the anode of the fuel cell without any external feed connectors and flow fields. The approach here is to use palladium film instead of feed connectors and the flow fields; palladium's property to adsorb and desorb the hydrogen at ambient and elevated condition. The proof of concept is demonstrated with a polymethyl methacrylate (PMMA) based complete system integration which includes microreactor, palladium transport layer and the self-breathing polymer electrolyte membrane (PEM) fuel cell. The hydrolysis of NaBH4 was carried out in the presence of platinum supported by nickel (NiPt). The prototype functionality is tested with NaBH4 chemical hydride. The characterization of the integrated palladium layer and fuel cell is tested with constant and switching load. The presented integrated fuel cell is observed to have a maximum power output and current of 60 mW and 280 mA respectively

  10. Growth of fluorescence gold clusters using photo-chemically activated ligands

    Science.gov (United States)

    Mishra, Dinesh; Aldeek, Fadi; Michael, Serge; Palui, Goutam; Mattoussi, Hedi

    2016-03-01

    Ligands made of lipoic acid (LA) appended with a polyethylene glycol (PEG) chain have been used in the aqueous phase growth of luminescent gold clusters with distinct emission from yellow to near-IR, using two different routes. In the first route, the gold-ligand complex was chemically reduced using sodium borohydride in alkaline medium, which gave near- IR luminescent gold clusters with maximum emission around 745 nm. In the second method, LA-PEG ligand was photochemically modified to a mixture of thiols, oligomers and oxygenated species under UV-irradiation, which was then used as both reducing agent and stabilizing ligand. By adjusting the pH, temperature, and time of the reaction, we were able to obtain clusters with two distinct emission properties. Refluxing the gold-ligand complex in alkaline medium in the presence of excess ligand gave yellow emission within the first two hours and the emission shifted to red after overnight reaction. Mass spectrometry and chemical assay were used to understand the photo-chemical transformation of Lipoic Acid (LA). Mass spectroscopic studies showed the photo-irradiated product contains thiols, oligomers (dimers, trimers and tetramers) as well as oxygenated species. The amount of thiol formed under different conditions of irradiation was estimated using Ellman's assay.

  11. Autonomously Propelled Motors for Value-Added Product Synthesis and Purification.

    Science.gov (United States)

    Srivastava, Sarvesh K; Schmidt, Oliver G

    2016-06-27

    A proof-of-concept design for autonomous, self-propelling motors towards value-added product synthesis and separation is presented. The hybrid motor design consists of two distinct functional blocks. The first, a sodium borohydride (NaBH4 ) granule, serves both as a reaction prerequisite for the reduction of vanillin and also as a localized solid-state fuel in the reaction mixture. The second capping functional block consisting of a graphene-polymer composite serves as a hydrophobic matrix to attract the reaction product vanillyl alcohol (VA), resulting in facile separation of this edible value-added product. These autonomously propelled motors were fabricated at a length scale down to 400 μm, and once introduced in the reaction environment showed rapid bubble-propulsion followed by high-purity separation of the reaction product (VA) by the virtue of the graphene-polymer cap acting as a mesoporous sponge. The concept has excellent potential towards the synthesis/isolation of industrially important compounds, affinity-based product separation, pollutant remediation (such as heavy metal chelation/adsorption), as well as localized fuel-gradients as an alternative to external fuel dependency. PMID:27123788

  12. Atomic layer deposited cobalt oxide: An efficient catalyst for NaBH{sub 4} hydrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Nandi, Dip K.; Manna, Joydev; Dhara, Arpan; Sharma, Pratibha; Sarkar, Shaibal K., E-mail: shaibal.sarkar@iitb.ac.in [Department of Energy Science and Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India)

    2016-01-15

    Thin films of cobalt oxide are deposited by atomic layer deposition using dicobalt octacarbonyl [Co{sub 2}(CO){sub 8}] and ozone (O{sub 3}) at 50 °C on microscope glass substrates and polished Si(111) wafers. Self-saturated growth mechanism is verified by x-ray reflectivity measurements. As-deposited films consist of both the crystalline phases; CoO and Co{sub 3}O{sub 4} that gets converted to pure cubic-Co{sub 3}O{sub 4} phase upon annealing at 500 °C under ambient condition. Elemental composition and uniformity of the films is examined by x-ray photoelectron spectroscopy and secondary ion-mass spectroscopy. Both as-deposited and the annealed films have been successfully tested as a catalyst for hydrogen evolution from sodium borohydride hydrolysis. The activation energy of the hydrolysis reaction in the presence of the as-grown catalyst is found to be ca. 38 kJ mol{sup −1}. Further implementation of multiwalled carbon nanotube, as a scaffold layer, improves the hydrogen generation rate by providing higher surface area of the deposited catalyst.

  13. First-principles predicted low-energy structures of NaSc(BH4)4

    Science.gov (United States)

    Tran, Huan Doan; Amsler, Maximilian; Botti, Silvana; Marques, Miguel A. L.; Goedecker, Stefan

    2014-03-01

    According to previous interpretations of experimental data, sodium-scandium double-cation borohydride NaSc(BH4)4 crystallizes in the crystallographic space group Cmcm where each sodium (scandium) atom is surrounded by six scandium (sodium) atoms. A careful investigation of this phase based on ab initio calculations indicates that the structure is dynamically unstable and gives rise to an energetically and dynamically more favorable phase with C2221 symmetry and nearly identical x-ray diffraction pattern. By additionally performing extensive structural searches with the minima-hopping method we discover a class of new low-energy structures exhibiting a novel structural motif in which each sodium (scandium) atom is surrounded by four scandium (sodium) atoms arranged at the corners of either a rectangle with nearly equal sides or a tetrahedron. These new phases are all predicted to be insulators with band gaps of 7.9-8.2 eV. Finally, we estimate the influence of these structures on the hydrogen-storage performance of NaSc(BH4)4.

  14. Graphene Dendrimer-stabilized silver nanoparticles for detection of methimazole using Surface-enhanced Raman scattering with computational assignment

    Science.gov (United States)

    Saleh, Tawfik A.; Al-Shalalfeh, Mutasem M.; Al-Saadi, Abdulaziz A.

    2016-01-01

    Graphene functionalized with polyamidoamine dendrimer, decorated with silver nanoparticles (G-D-Ag), was synthesized and evaluated as a substrate with surface-enhanced Raman scattering (SERS) for methimazole (MTZ) detection. Sodium borohydride was used as a reducing agent to cultivate silver nanoparticles on the dendrimer. The obtained G-D-Ag was characterized by using UV-vis spectroscopy, scanning electron microscope (SEM), high-resolution transmission electron microscope (TEM), Fourier-transformed infrared (FT-IR) and Raman spectroscopy. The SEM image indicated the successful formation of the G-D-Ag. The behavior of MTZ on the G-D-Ag as a reliable and robust substrate was investigated by SERS, which indicated mostly a chemical interaction between G-D-Ag and MTZ. The bands of the MTZ normal spectra at 1538, 1463, 1342, 1278, 1156, 1092, 1016, 600, 525 and 410 cm−1 were enhanced due to the SERS effect. Correlations between the logarithmical scale of MTZ concentrations and SERS signal intensities were established, and a low detection limit of 1.43 × 10−12 M was successfully obtained. The density functional theory (DFT) approach was utilized to provide reliable assignment of the key Raman bands. PMID:27572919

  15. The impact of kappa number composition on eucalyptus kraft pulp bleachability

    Directory of Open Access Journals (Sweden)

    M. M. Costa

    2007-03-01

    Full Text Available Consumption of chemicals during ECF bleaching of kraft pulp correlates reasonably well with kappa number, which measures with KMnO4 the total amount of oxidizable material in the pulp. However, the method does not distinguish between the oxidizable material in residual lignin and other structures susceptible to oxidation, such as hexenuronic acids (HexAs, extractives and carbonyl groups in the pulp. In this study an attempt is made to separate the main contributors to the kappa number in oxygen - delignified eucalyptus Kraft pulps and evaluate how these fractions behave during ECF bleaching using chlorine dioxide as the sole oxidant (DEDD sequence. Residual lignin and HexAs proved to be the main fractions contributing to the kappa number and chlorine dioxide consumption in ECF bleaching. Pulp bleachability with chlorine dioxide increases with increasing HexAs content of the pulp but chlorine dioxide per se does not react with HexAs. Reduction of pulp with sodium borohydride under conditions for removing carbonyl groups has no impact on bleachability. No correlation was found between the pulp of the extractive content and pulp bleachability. The removal of HexAs prior to ECF bleaching significantly decreases the formation of chlorinated organics in the pulp (OX and filtrates (AOX as well as of oxalic acids in the filtrates.

  16. Investigation of oxygen reduction and methanol oxidation reaction activity of PtAu nano-alloy on surface modified porous hybrid nanocarbon supports

    Science.gov (United States)

    Parambath Vinayan, Bhaghavathi; Nagar, Rupali; Ramaprabhu, Sundara

    2016-09-01

    We investigate the electrocatalytic activity of PtAu alloy nanoparticles supported on various chemically modified carbon morphologies towards oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR). The surface-modification of graphene nanosheets (f-G), multi-walled carbon nanotubes (f-MWNTs) and (graphene nanosheets-carbon nanotubes) hybrid support (f-G-MWNTs) were carried out by soft functionalization method using a cationic polyelectrolyte poly-(diallyldimethyl ammonium chloride). The Pt and PtAu alloy nanoparticles were dispersed over chemically modified carbon supports by sodium-borohydride assisted modified polyol reduction method. The electrochemical performance of all electrocatalysts were studied by half- and full-cell proton exchange membrane fuel cell (PEMFC) measurements and PtAu/f-G-MWNTs catalyst comparatively yielded the best catalytic performance. PEMFC full cell measurements of PtAu/f-G-MWNTs cathode electrocatalyst yield a maximum power density of 319 mW cm-2 at 60 °C without any back pressure,which is 2.1 times higher than that of cathode electrocatalyst Pt on graphene support. The high ORR and MOR activity of PtAu/f-G-MWNTs electrocatalyst is due to the alloying effect and inherent beneficial properties of porous hybrid nanocarbon support.

  17. Isolation of Human Genomic DNA Sequences with Expanded Nucleobase Selectivity.

    Science.gov (United States)

    Rathi, Preeti; Maurer, Sara; Kubik, Grzegorz; Summerer, Daniel

    2016-08-10

    We report the direct isolation of user-defined DNA sequences from the human genome with programmable selectivity for both canonical and epigenetic nucleobases. This is enabled by the use of engineered transcription-activator-like effectors (TALEs) as DNA major groove-binding probes in affinity enrichment. The approach provides the direct quantification of 5-methylcytosine (5mC) levels at single genomic nucleotide positions in a strand-specific manner. We demonstrate the simple, multiplexed typing of a variety of epigenetic cancer biomarker 5mC with custom TALE mixes. Compared to antibodies as the most widely used affinity probes for 5mC analysis, i.e., employed in the methylated DNA immunoprecipitation (MeDIP) protocol, TALEs provide superior sensitivity, resolution and technical ease. We engineer a range of size-reduced TALE repeats and establish full selectivity profiles for their binding to all five human cytosine nucleobases. These provide insights into their nucleobase recognition mechanisms and reveal the ability of TALEs to isolate genomic target sequences with selectivity for single 5-hydroxymethylcytosine and, in combination with sodium borohydride reduction, single 5-formylcytosine nucleobases. PMID:27429302

  18. One-step preparation of Fe3O4/Pd@polypyrrole composites with enhanced catalytic activity and stability.

    Science.gov (United States)

    Zhang, Hui; Liu, Yang; Wu, Jie; Xin, Baifu

    2016-08-15

    Core/shell Fe3O4/Pd@polypyrrole (PPy) composites with a Fe3O4 core and a PPy shell embedding Pd nanoparticles were prepared in one-step. The diameter of highly dispersed Pd nanoparticles was as small as 2.9nm owing to coordination interaction generated between Pd(2+) ions and amino groups on PPy chains. The outer PPy shell was only 6.8nm: on one hand, the coverage was beneficial to improving the stability of resulting composites; on the other hand, the shell was thin enough to permit free contact between embedding Pd nanoparticles and reactants. Additionally, the as-prepared Fe3O4/Pd@PPy composites displayed good magnetic separation property due to incorporation of Fe3O4 nanospheres. Based on above merits, they served as suitable catalyst candidates. Their catalytic performance and reusability were evaluated by reduction of 4-nitrophenol with sodium borohydride as reducing agent. Compared with traditional Fe3O4/Pd composites, Fe3O4/Pd@PPy composites not only showed superior catalytic activity; but also exhibited much better stability in successive cycling tests.

  19. Histochemical and structural analysis of mucous glycoprotein secreted by the gill of Mytilus edulis

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Hae-Young.

    1988-01-01

    Studies were carried out to characterized various mucous cells in the gill filament, to ascertain structural characteristics of the secreted mucous glycoproteins, and to determine the ability of the gill epithelium to incorporate ({sup 14}C)glucosamine as a precursor in the biosynthesis and secretion of mucous glycoproteins. Using histochemical staining techniques, mucous cells containing neutral and acidic mucins were found in the lateral region, whereas mucous cells containing primarily neutral or sulfated mucins were found in the postlateral region. Serotonin, but not dopamine, stimulated the mucous secretion. In tissues pretreated with ({sup 14}C)glucosamine, the secreted glycoproteins contain incorporated radiolabel. Analysis by column chromatography using Bio-Gel P-2 and P-6 shows that the secretion contains two glycoprotein populations. Glycoprotein II has a molecular weight of 2.3 {times} 10{sup 4} daltons. Upon alkaline reductive borohydride cleavage of the O-glycosidic linkages of glycoprotein I, about 70% of the radiolabel was removed from the protein. Gas chromatographic analysis of the carbohydrate composition shows that the glycoproteins contains N-acetylglucosamine (GluNAc), N-acetylgalactosamine (GalNAc), and galactose, fucose and mannose. Amino acid analysis shows that the glycoproteins are rich in serine, threonine and proline.

  20. Biosynthesis of ascites sialoglycoprotein-1, the major O-linked glycoprotein of 13762 rat mammary adenocarcinoma ascites cells

    Energy Technology Data Exchange (ETDEWEB)

    Spielman, J.

    1987-01-01

    The present studies were undertaken to determine the timing of the major events in biosynthesis, and to characterize the contributions of chain initiation and elongation in maturation of the glycoprotein. Initiation of the earliest O-linked chains was detected by analysis of conversion of {sup 3}H-thr to {sup 3}H 2-aminobutyrate following mild alkaline borohydride elimination of O-linked sugars from peanut lectin-precipitated ASGP-1. Initiation was detected within 5 min of translation; amino sugar analysis of GlcNH{sub 2}-labeled, trypsinized cells also showed that GalNAc was added as late as 5 min prior to arrival of ASGP-1 at the cell surface. Thus initiation occurs throughout biosynthesis. Maturation of the glycoprotein from a lightly-glycosylated immature form to the heavily-glycosylated mature from involved both continued initiation of new chains and chain elongation, and occurred with a half-time of about 30 min. Analysis of labeled ASGP-1 released from the cell surface by trypsinization showed that although some newly-synthesized ASGP-1 reached the cell surface within 70-80 min of protein synthesis, the half-time for appearance of mature glycoprotein was in excess of 4 hr, indicating that most molecules reside in an intracellular compartment(s) for a considerable time.

  1. S-3-奎宁醇的合成研究%Study on the Synthesis of S-3-Quinine Alcohol

    Institute of Scientific and Technical Information of China (English)

    任彦荣

    2012-01-01

    A new method is reported for synthesizingS-3-quininealcohoL Based on a configuration transformation strategy, the raw material 3-quinineketoneis, in turn, reduced,esterified, and finally hydrolyzed into S-3-quinine alcohol by potassium borohydride, acetyl chloride, and sodium hydroxide, respectively- Subsequently, 1H NMRcharacterization is employed to confirm the S -3 -quinine alcohol and HPLC also reveals that theoverall yield of the desired product isabout 88-96%-The proposedsynthesis method appears to be convenient,high-yielding, and applicable for industrial purpose.%探讨S-3-奎宁醇的合成新工艺.通过构型转化的方法,以3-奎宁酮为原料,经硼氢化钾还原、与乙酰氯成酯、水解得S-3-奎宁醇.其结构经1H NMR等表征证实,总收率可达到88.96%.该合成路线操作步骤简单、收率高,具有工业应用价值.

  2. Fullerene-ionic-liquid conjugates: a new class of hybrid materials with unprecedented properties.

    Science.gov (United States)

    Campisciano, Vincenzo; La Parola, Valeria; Liotta, Leonarda F; Giacalone, Francesco; Gruttadauria, Michelangelo

    2015-02-16

    A modular approach has been followed for the synthesis of a series of fullerene-ionic-liquid (IL) hybrids in which the number of IL moieties (two or twelve), anion, and cation have been varied. The combination of C60 and IL give rise to new unique properties in the conjugates such as solubility in water, which was higher than 800 mg mL(-1) in several cases. In addition, one of the C60 -IL hybrids has been employed for the immobilization of palladium nanoparticles through ion exchange followed by reduction with sodium borohydride. Surprisingly, during the reduction several carbon nanostructures were formed that comprised nano-onions and nanocages with few-layer graphene sidewalls, which have been characterized by means of thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy/energy-dispersive X-ray analysis (SEM-EDAX), and high-resolution transmission electron microscopy (HRTEM). Finally, the material thus obtained was successfully applied as catalyst in Suzuki and Mizoroki-Heck reactions in a concentration of just 0.2 mol %. In the former process it was recyclable for five runs with no loss in activity. PMID:25589382

  3. Graphene Dendrimer-stabilized silver nanoparticles for detection of methimazole using Surface-enhanced Raman scattering with computational assignment.

    Science.gov (United States)

    Saleh, Tawfik A; Al-Shalalfeh, Mutasem M; Al-Saadi, Abdulaziz A

    2016-01-01

    Graphene functionalized with polyamidoamine dendrimer, decorated with silver nanoparticles (G-D-Ag), was synthesized and evaluated as a substrate with surface-enhanced Raman scattering (SERS) for methimazole (MTZ) detection. Sodium borohydride was used as a reducing agent to cultivate silver nanoparticles on the dendrimer. The obtained G-D-Ag was characterized by using UV-vis spectroscopy, scanning electron microscope (SEM), high-resolution transmission electron microscope (TEM), Fourier-transformed infrared (FT-IR) and Raman spectroscopy. The SEM image indicated the successful formation of the G-D-Ag. The behavior of MTZ on the G-D-Ag as a reliable and robust substrate was investigated by SERS, which indicated mostly a chemical interaction between G-D-Ag and MTZ. The bands of the MTZ normal spectra at 1538, 1463, 1342, 1278, 1156, 1092, 1016, 600, 525 and 410 cm(-1) were enhanced due to the SERS effect. Correlations between the logarithmical scale of MTZ concentrations and SERS signal intensities were established, and a low detection limit of 1.43 × 10(-12) M was successfully obtained. The density functional theory (DFT) approach was utilized to provide reliable assignment of the key Raman bands. PMID:27572919

  4. One-step preparation of Fe3O4/Pd@polypyrrole composites with enhanced catalytic activity and stability.

    Science.gov (United States)

    Zhang, Hui; Liu, Yang; Wu, Jie; Xin, Baifu

    2016-08-15

    Core/shell Fe3O4/Pd@polypyrrole (PPy) composites with a Fe3O4 core and a PPy shell embedding Pd nanoparticles were prepared in one-step. The diameter of highly dispersed Pd nanoparticles was as small as 2.9nm owing to coordination interaction generated between Pd(2+) ions and amino groups on PPy chains. The outer PPy shell was only 6.8nm: on one hand, the coverage was beneficial to improving the stability of resulting composites; on the other hand, the shell was thin enough to permit free contact between embedding Pd nanoparticles and reactants. Additionally, the as-prepared Fe3O4/Pd@PPy composites displayed good magnetic separation property due to incorporation of Fe3O4 nanospheres. Based on above merits, they served as suitable catalyst candidates. Their catalytic performance and reusability were evaluated by reduction of 4-nitrophenol with sodium borohydride as reducing agent. Compared with traditional Fe3O4/Pd composites, Fe3O4/Pd@PPy composites not only showed superior catalytic activity; but also exhibited much better stability in successive cycling tests. PMID:27232537

  5. Characterization and electrocatalytic properties of sonochemical synthesized PdAg nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Godinez-Garcia, Andres, E-mail: agodinez@qro.cinvestav.mx [Depto. Materiales, Centro de Investigacion y de Estudios Avanzados del IPN, Libramiento norponiente 2000, Fracc. Real de Juriquilla, C.P. 76230 Santiago de Queretaro, Qro. (Mexico); Perez-Robles, Juan Francisco [Depto. Materiales, Centro de Investigacion y de Estudios Avanzados del IPN, Libramiento norponiente 2000, Fracc. Real de Juriquilla, C.P. 76230 Santiago de Queretaro, Qro. (Mexico); Martinez-Tejada, Hader Vladimir [Grupo de Energia y Termodinamica, Universidad Pontificia Bolivariana, Medellin, Antioquia C.P. 050031 (Colombia); Solorza-Feria, Omar [Depto. Quimica, CINVESTAV-IPN, Av. IPN 2508, A. P. 14-740, 07360 D.F. Mexico (Mexico)

    2012-06-15

    High intensity ultrasound was used in the synthesis of PdAg nanoparticles. PdAg nanoparticles were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), energy dispersive spectroscopy (EDS), scanning transmission electron microscopy (STEM) and high-resolution transmission electron microscopy (HRTEM). Catalytic properties for oxygen reduction reaction (ORR) were determined by electrochemical techniques of cyclic voltammetry (CV) and thin-film rotating disk electrode (TF-RDE). Finally the electrocatalyst was tested as a cathode in a single polymer electrolyte membrane fuel cell (PEMFC). Sonochemical synthesis (SS) decreased the overpotential required for the ORR and increased the double-layer capacitance (DLC) respect to the sodium borohydride reduction method due to a better distribution on vulcan carbon support. The electrocatalytic activity of the nanometric bimetallic electrocatalyst for the ORR in acid media showed a favorable multielectron charge transfer process (n = 4e{sup -}) to water formation. The performance of the membrane electrode assembly (MEA) prepared with dispersed PdAg/C as a cathode catalyst in a single PEMFC is lower in comparison to platinum. - Highlights: Black-Right-Pointing-Pointer Sonochemical synthesized PdAg nanoparticles supported on carbon were produced. Black-Right-Pointing-Pointer The material showed catalytic properties for the oxygen reduction reaction (ORR). Black-Right-Pointing-Pointer The ORR favored the pathway to water formation.

  6. Structure/toxicity relationships and fate of low molecular weight peptide toxins from cyanobacteria

    International Nuclear Information System (INIS)

    Hepatic glutathione (GSH) was depleted to assess the influence of GSH on the toxicity of MCYST-LR in vivo. The GSH conjugate of MCYST-LR was also formed synthetically. There was an approximately four-fold decrease in the toxicity of the GSH derivative, as compared to the parent toxin; but the GSH conjugate remained hepatotoxic and hepatospecific in its effects. Tritium-labeled sodium borohydride was used to produced tritium-labeled 2H-MCYST-LR. The labeled toxin was administered intraperitoneally to male mice in lethal or sublethal doses, and the organ distributions measured over a 60 min observation period. Sublethal doses were also administered to a second group of mice and the excretion of radioactivity in urine and feces was measured at 12 hr intervals for 72 hr, along with tissue distribution at the end of the observation period. Accumulation of labeled toxin in the livers of treated animals was rapid with 94.7 ± 3.3% (mean ± S.D.) of the sublethal dose present in the liver after 1 hr, and 57.8 ± 5.2% of the administered dose present 72 hr after administration. The small intestine also accumulated radioactivity in both treatment groups. Excretion of the toxin in sublethally dosed animals occurred primarily via the feces

  7. Micromotor-based energy generation.

    Science.gov (United States)

    Singh, Virendra V; Soto, Fernando; Kaufmann, Kevin; Wang, Joseph

    2015-06-01

    A micromotor-based strategy for energy generation, utilizing the conversion of liquid-phase hydrogen to usable hydrogen gas (H2), is described. The new motion-based H2-generation concept relies on the movement of Pt-black/Ti Janus microparticle motors in a solution of sodium borohydride (NaBH4) fuel. This is the first report of using NaBH4 for powering micromotors. The autonomous motion of these catalytic micromotors, as well as their bubble generation, leads to enhanced mixing and transport of NaBH4 towards the Pt-black catalytic surface (compared to static microparticles or films), and hence to a substantially faster rate of H2 production. The practical utility of these micromotors is illustrated by powering a hydrogen-oxygen fuel cell car by an on-board motion-based hydrogen and oxygen generation. The new micromotor approach paves the way for the development of efficient on-site energy generation for powering external devices or meeting growing demands on the energy grid.

  8. Influence of Sn on the magnetic ordering of Ni-Sn alloy synthesized using chemical reduction method

    Science.gov (United States)

    Dhanapal, K.; Narayanan, V.; Stephen, A.

    2016-05-01

    The Ni-Sn alloy was synthesized using borohydride assisted chemical reduction method. The composition of the synthesized alloy was determined using atomic absorption spectroscopy which revealed that the observed composition of Sn is high when compared to the initial composition. The ultrafine particles are clearly observed from field emission scanning electron microscope for all the sample. The X-ray diffraction measurement confirmed that the as-synthesized samples are of amorphous like nature while the samples annealed at 773 K showed crystalline nature. The Fourier transform infrared spectroscopy confirmed metallic bond stretching in the alloy samples. The crystallization and phase transition temperature was observed from differential scanning calorimetry. The shift in the crystallization temperature of Ni with increasing percentage of Sn was observed. The vibrating sample magnetometer was employed to understand the magnetic behavior of the Ni-Sn alloy. As-synthesized alloy samples showed paramagnetic nature while the annealed ones exhibit the soft ferromagnetic, antiferromagnetic and paramagnetic nature. The saturation magnetization value and magnetic ordering in the Ni-Sn alloys depend on the percentage of Sn present in the alloy.

  9. Fabrication of Bi-Fe3O4@RGO hybrids and their catalytic performance for the reduction of 4-nitrophenol

    International Nuclear Information System (INIS)

    Nanocatalysts are frequently connected to magnetic nanoparticles. These composites are easy to be retrieved from the reaction system under a magnetic field because of their magnetic properties. Magnetic separation is particularly promising in industry since it can solve many issues present in filtration, centrifugation, or gravitation separation. Herein, a facile method to prepare bismuth and Fe3O4 nanoparticles loaded on reduced graphene oxide magnetic hybrids (Bi-Fe3O4@RGO) using soluble starch as a dispersant is demonstrated. The magnetic Fe3O4 nanoparticles were synthesized by the co-precipitation of Fe2+ and Fe3+ ions, and Bi nanoparticles were fabricated by the redox reactions between sodium borohydride and ammonium bismuth citrate in the presence of soluble starch. Transmission electron microscopy images demonstrate that the average diameter of the Fe3O4 nanoparticles is about 5 nm and the diameters of Bi nanoparticles range from 10 to 20 nm. The magnetic Bi-Fe3O4@RGO hybrids exhibit high catalytic activity in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by NaBH4 with a first-order rate constant (K) of 0.00808 s−1 and is magnetically recyclable for at least five cycles. This strategy provides an efficient and recyclable catalyst for the use in environmental protection applications

  10. Topological disposition of the sequences -QRKIVE- and -KETYY in native (Na+ + K+)-ATPase

    International Nuclear Information System (INIS)

    The dispositions with respect to the plane of the membrane of lysine-905 in the internal sequence -EQRKIVE- and of lysine-1012 in the carboxy-terminal sequence -RRPGGWVEKETYY of the α-polypeptide of sodium and potassium ion activated adenosinetriphosphatase have been determined. These lysines are found in peptides released from the intact α-polypeptide by the extracellular protease from Staphylococcus aureus strain V8 and by trypsin, respectively. Synthetic peptides containing terminal sequences of these were used to prepare polyclonal antibodies, which were then used to prepare immunoadsorbents directed against the respective peptides. Sealed, right-side-out membrane vesicles containing native (Na+ + K+)-ATPase were labeled with pyridoxal phosphate and sodium [3H]borohydride in the absence or presence of saponin. The labeled α-polypeptide was isolated from these vesicles and digested with appropriate proteases. The incorporation of radioactivity into the peptides binding to the immunoadsorbent directed against the sequence pyrERXIVE increased 3-fold int the presence of saponin as a result of the increased accessibility of this portion of the protein to the reagent when the vesicles were breached by saponin; hence, this sequence is located on the cytoplasmic face of the membrane. It was inferred that the carboxy-terminal sequence -KETYY is on the extracytoplasmic face since the incorporation of radioactivity into peptides binding to the immunoadsorbent directed against the sequence -ETYY did not change when the vesicles were breached with saponin

  11. Synthesis of diphenylalanine/cobalt oxide hybrid nanowires and their application to energy storage.

    Science.gov (United States)

    Ryu, Jungki; Kim, Sung-Wook; Kang, Kisuk; Park, Chan Beum

    2010-01-26

    We report the synthesis of novel diphenylalanine/cobalt(II,III) oxide (Co(3)O(4)) composite nanowires by peptide self-assembly. Peptide nanowires were prepared by treating amorphous diphenylalanine film with aniline vapor at an elevated temperature. They were hybridized with Co(3)O(4) nanocrystals through the reduction of cobalt ions in an aqueous solution using sodium borohydride (NaBH(4)) without any complex processes such as heat treatment. The formation of peptide/Co(3)O(4) composite nanowires was characterized using multiple tools, such as electron microscopies and elemental analysis, and their potential application as a negative electrode for Li-ion batteries was explored by constructing Swagelok-type cells with hybrid nanowires as a working electrode and examining their charge/discharge behavior. The present study provides a useful approach for the synthesis of functional metal oxide nanomaterials by demonstrating the feasibility of peptide/Co(3)O(4) hybrid nanowires as an energy storage material. PMID:20000841

  12. INFLUENCE OF MOLECULAR WEIGHT AND PERIODATE-MODIFICATION OF β-D-GLUCANS FROM PORIA COCOS SCLEROTIUM ON ANTITUMOR ACTIVITIES

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    In this work, influence of molecular weight and periodate modification of β-D-glucans isolated from Poria cocos sclerotium on the antitumor activities against Sarcoma 180 and Ehrlich ascites carcinoma (EAC) tumor was studied. The results show that two glucans PC3 (linear β-(1 → 3)-D-glucan) and PC4 [β-(1 → 3)-D-glucan with a few of branches and glucuronic acid] are devoid of antitumor activity. However, when the glucans were modified by periodate oxidation, borohydride reduction and mild hydrolysis or partially hydrolysis, the derivatives have obvious antitumor activities. The decrease in molecular weight of glucans after periodate modification hardly affects their antitumor actions, but on the other hand, the decrease of molecular weight without periodate modification could lead to an enhancement of the antitumor activities. Moreover, the glucans and these derivatives have much higher enhancement ratios of body weight of mice than that of 5-Fluorouracil (5-Fu), suggesting that they are less toxic than 5-Fu.

  13. A high performance cobalt sulfide counter electrode for dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Highlights: • CoS electrode is prepared by repetitive electrophoretic and ion exchange depositions. • The CoS has honeycomb-like structure, good catalytic activity and lower resistances. • DSSC with CoS-4AB obtains a PCE of 7.72%, higher than the cell with Pt electrode. - Abstract: A cobalt sulfide (CoS) thin film is deposited on fluorine doped SnO2 (FTO) glass by repetitive electrophoretic deposition (EPD) and ion exchange deposition (IED), then the thin film is treated with sodium borohydride or/and sulfuric acid solution. The film is used as the counter electrode of dye-sensitized solar cells (DSSCs), and is characterized by field emission scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy and Tafel measurements. The results show that the CoS counter electrode has a honeycomb-like morphology with large specific surface area, good catalytic activity for reduction of I3−, lower charge-transfer and series resistances, which result in the better electrochemical property of CoS counter electrodes. Under a simulated solar light irradiation of 100 mW cm−2, the DSSC based on the CoS counter electrode achieves a power conversion efficiency of 7.72%, thus, synthesized CoS can serve as an efficient Pt-free counter electrode material for DSSCs

  14. Template-Assisted Synthesis and Characterization of Passivated Nickel Nanoparticles

    Science.gov (United States)

    Veena Gopalan, E.; Malini, K. A.; Santhoshkumar, G.; Narayanan, T. N.; Joy, P. A.; Al-Omari, I. A.; Sakthi Kumar, D.; Yoshida, Yasuhiko; Anantharaman, M. R.

    2010-05-01

    Potential applications of nickel nanoparticles demand the synthesis of self-protected nickel nanoparticles by different synthesis techniques. A novel and simple technique for the synthesis of self-protected nickel nanoparticles is realized by the inter-matrix synthesis of nickel nanoparticles by cation exchange reduction in two types of resins. Two different polymer templates namely strongly acidic cation exchange resins and weakly acidic cation exchange resins provided with cation exchange sites which can anchor metal cations by the ion exchange process are used. The nickel ions which are held at the cation exchange sites by ion fixation can be subsequently reduced to metal nanoparticles by using sodium borohydride as the reducing agent. The composites are cycled repeating the loading reduction cycle involved in the synthesis procedure. X-Ray Diffraction, Scanning Electron Microscopy, Transmission Electron microscopy, Energy Dispersive Spectrum, and Inductively Coupled Plasma Analysis are effectively utilized to investigate the different structural characteristics of the nanocomposites. The hysteresis loop parameters namely saturation magnetization and coercivity are measured using Vibrating Sample Magnetometer. The thermomagnetization study is also conducted to evaluate the Curie temperature values of the composites. The effect of cycling on the structural and magnetic characteristics of the two composites are dealt in detail. A comparison between the different characteristics of the two nanocomposites is also provided.

  15. Template-Assisted Synthesis and Characterization of Passivated Nickel Nanoparticles

    Directory of Open Access Journals (Sweden)

    Al-Omari IA

    2010-01-01

    Full Text Available Abstract Potential applications of nickel nanoparticles demand the synthesis of self-protected nickel nanoparticles by different synthesis techniques. A novel and simple technique for the synthesis of self-protected nickel nanoparticles is realized by the inter-matrix synthesis of nickel nanoparticles by cation exchange reduction in two types of resins. Two different polymer templates namely strongly acidic cation exchange resins and weakly acidic cation exchange resins provided with cation exchange sites which can anchor metal cations by the ion exchange process are used. The nickel ions which are held at the cation exchange sites by ion fixation can be subsequently reduced to metal nanoparticles by using sodium borohydride as the reducing agent. The composites are cycled repeating the loading reduction cycle involved in the synthesis procedure. X-Ray Diffraction, Scanning Electron Microscopy, Transmission Electron microscopy, Energy Dispersive Spectrum, and Inductively Coupled Plasma Analysis are effectively utilized to investigate the different structural characteristics of the nanocomposites. The hysteresis loop parameters namely saturation magnetization and coercivity are measured using Vibrating Sample Magnetometer. The thermomagnetization study is also conducted to evaluate the Curie temperature values of the composites. The effect of cycling on the structural and magnetic characteristics of the two composites are dealt in detail. A comparison between the different characteristics of the two nanocomposites is also provided.

  16. Antimicrobial chitosan-PVA hydrogel as a nanoreactor and immobilizing matrix for silver nanoparticles

    Science.gov (United States)

    Agnihotri, Shekhar; Mukherji, Soumyo; Mukherji, Suparna

    2012-09-01

    Hydrogels are water-insoluble crosslinked hydrophilic networks capable of retaining a large amount of water. The present work aimed to develop a novel chitosan-PVA-based hydrogel which could behave both as a nanoreactor and an immobilizing matrix for silver nanoparticles (AgNPs) with promising antibacterial applications. The hydrogel containing AgNPs were prepared by repeated freeze-thaw treatment using varying amounts of the crosslinker, followed by in situ reduction with sodium borohydride as a reducing agent. Characterization studies established that the hydrogel provides a controlled and uniform distribution of nanoparticles within the polymeric network without addition of any further stabilizer. The average particle size was found to be 13 nm with size distribution from 8 to 21 nm as per HR-TEM studies. Swelling studies confirmed that higher amount of crosslinker and silver incorporation inside the gel matrices significantly enhanced the porosity and chain entanglement of the polymeric species of the hydrogel, respectively. The AgNP-hydrogel exhibited good antibacterial activity and was found to cause significant reduction in microbial growth ( Escherichia coli) in 12 h while such activity was not observed for the hydrogel without AgNPs.

  17. Mechanism for formation of NaBH4 proposed as low-pressure process for storing hydrogen in borosilicate glass–sodium solid system: a hydrogen storage material

    Indian Academy of Sciences (India)

    Aysel Kantürk Figen; Sabriye Pişkin

    2012-04-01

    The mechanism for the formation of sodium borohydride (NaBH4) was investigated for its ability to store hydrogen in the borosilicate glass–sodium (BSG–Na) solid system under low hydrogen pressure. BSG, which was prepared by melting borax with silica, was used as the starting material in the BSG–Na system that would be prepared to store hydrogen. It was observed that the mechanism for storing hydrogen in the BSG–Na solid system consisted of six steps and when the BSG–Na system was heated under a pressure of 4 atm, which was created through the use of hydrogen atmosphere, the storage of hydrogen occurred at nearly 480°C for approximate duration of 200 min, with the excellent yield (97%). In addition, the hydrogen storage capacity of the NaBH4 sample was measured using the Au–PS structure, which was designed as a mini-hydrogen cell. It was determined that the minimum amount of NaBH4 to generate the maximum volume of hydrogen gas was 12 mg/ml at 270 mV.

  18. Green synthesis of iron nanoparticles by various tea extracts: Comparative study of the reactivity

    Science.gov (United States)

    Huang, Lanlan; Weng, Xiulan; Chen, Zuliang; Megharaj, Mallavarapu; Naidu, Ravendra

    2014-09-01

    Iron nanoparticles (Fe NPs) are often synthesized using sodium borohydride with aggregation, which is a high cost process and environmentally toxic. To address these issues, Fe NPs were synthesized using green methods based on tea extracts, including green, oolong and black teas. The best method for degrading malachite green (MG) was Fe NPs synthesized by green tea extracts because it contains a high concentration of caffeine/polyphenols which act as both reducing and capping agents in the synthesis of Fe NPs. These characteristics were confirmed by a scanning electron microscope (SEM), UV-visible (UV-vis) and specific surface area (BET). To understand the formation of Fe NPs using various tea extracts, the synthesized Fe NPs were characterized by SEM, X-ray energy-dispersive spectrometer (EDS), and X-ray diffraction (XRD). What emerged were different sizes and concentrations of Fe NPs being synthesized by tea extracts, leading to various degradations of MG. Furthermore, kinetics for the degradation of MG using these Fe NPs fitted well to the pseudo first-order reaction kinetics model with more than 20 kJ/mol activation energy, suggesting a chemically diffusion-controlled reaction. The degradation mechanism using these Fe NPs included adsorption of MG to Fe NPs, oxidation of iron, and cleaving the bond that was connected to the benzene ring.

  19. Oxygen reduction reaction catalyzed by platinum nanonetwork prepared by template free one step synthesis for polymer electrolyte membrane fuel cells

    International Nuclear Information System (INIS)

    Highlights: • Supportless Pt nanonetwork (Pt NN) synthesized by novel template free one step method as per our earlier reported procedure. • Electrocatalytic activity of Pt NN studied taking oxygen reduction reaction in acid medium. • Kinetic and thermodynamic parameters were deduced under hydrodynamic conditions. • ORR mechanistic pathway was proposed based on kinetic rate constants. • ADT analysis found enhanced stability (5000 cycles) for Pt NN than Pt NN/VC and reported Pt/C. - Abstract: The reduction reaction of molecular oxygen (ORR) was investigated using supportless Pt nanonetwork (Pt NN) electrocatalyst in sulfuric acid medium. Pt NN was prepared by template free borohydride reduction. The transmission electron microscope images revealed a network like nano-architecture having an average cluster size of 30 nm. The electrochemical characterization of supportless and Vulcan carbon supported Pt NN (Pt NN/VC) was carried out using rotating disc and ring disc electrodes at various temperatures. Kinetic and thermodynamic parameters were estimated under hydrodynamic conditions and compared with Pt NN/VC and reported Pt/C catalysts. The accelerated durability test revealed that supportless Pt NN is quite stable for 5000 potential cycles with 22% reduction in electrochemical surface area (ECSA). While the initial limiting current density has in fact increased by 11.6%, whereas Pt NN/VC suffered nearly 55% loss in ECSA and 13% loss in limiting current density confirming an enhanced stability of supportless Pt NN morphology for ORR compared to conventional Pt/C ORR catalysts in acid medium

  20. Catalytic Reductive Degradation of Methyl Orange Using Air Resilient Copper Nanostructures

    Directory of Open Access Journals (Sweden)

    Razium Ali Soomro

    2015-01-01

    Full Text Available The study describes the application of oxidation resistant copper nanostructures as an efficient heterogeneous catalyst for the treatment of organic dye containing waste waters. Copper nanostructures were synthesized in an aqueous environment using modified surfactant assisted chemical reduction route. The synthesized nanostructures have been characterized by UV-Vis, Fourier transform infrared spectroscopy FTIR spectroscopy, Atomic force microscopy (AFM, Scanning Electron Microscopy (SEM, and X-ray diffractometry (XRD. These surfactant capped Cu nanostructures have been used as a heterogeneous catalyst for the comparative reductive degradation of methyl orange (MO in the presence of sodium borohydride (NaBH4 used as a potential reductant. Copper nanoparticles (Cu NPs were found to be more efficient compared to copper nanorods (Cu NRds with the degradation reaction obeying pseudofirst order reaction kinetics. Shape dependent catalytic efficiency was further evaluated from activation energy (EA of reductive degradation reaction. The more efficient Cu NPs were further employed for reductive degradation of real waste water samples containing dyes collected from the drain of different local textile industries situated in Hyderabad region, Pakistan.

  1. Reviewing the Tannic Acid Mediated Synthesis of Metal Nanoparticles

    Directory of Open Access Journals (Sweden)

    Tufail Ahmad

    2014-01-01

    Full Text Available Metal nanoparticles harbour numerous exceptional physiochemical properties absolutely different from those of bulk metal as a function of their extremely small size and large superficial area to volume. Naked metal nanoparticles are synthesized by various physical and chemical methods. Chemical methods involving metal salt reduction in solution enjoy an extra edge over other protocols owing to their relative facileness and capability of controlling particle size along with the attribute of surface tailoring. Although chemical methods are the easiest, they are marred by the use of hazardous chemicals such as borohydrides. This has led to inclination of scientific community towards eco-friendly agents for the reduction of metal salts to form nanoparticles. Tannic acid, a plant derived polyphenolic compound, is one such agent which embodies characteristics of being harmless and environmentally friendly combined with being a good reducing and stabilizing agent. In this review, first various methods used to prepare metal nanoparticles are highlighted and further tannic acid mediated synthesis of metal nanoparticles is emphasized. This review brings forth the most recent findings on this issue.

  2. Synthesis of the d,I-HM-PAO and formulation of nucleo-equipment for the obtention of {sup 99m} Tc-(d,I)-HM-PAO; Sintesis del d,I-HM-PAO y formulacion de nucleo-equipos para la obtencion de {sup 99m} Tc-(d,I)-HM-PAO

    Energy Technology Data Exchange (ETDEWEB)

    Lezama C, J.; Ferro F, G.; Alcazar A, P

    1991-09-15

    Most brain imaging radiopharmaceuticals are conventional hydrophilic compounds that are excluded from entering the normal brain by an intact blood-brain barrier (BBB). Under pathologic conditions, the barrier is disrupted and radiotracer concentrates in the leisure for positive identification. {sup 99m} Tc- hexa methyl propylene amine oxime ({sup 99} {sup m} Tc-HM-PAO) is a newer-type lipophilic agent that enter the normal brain through an intact BBB. Studies with this agent offer the promise of measuring cerebral perfusion in the normal and diseased brain. In this paper we present the synthesis and Tc-99m labelling of d,I-HM-PAO. The synthesis of the ligand was carried out by condensation of two molecular equivalents of butanedione monoxime with one molecular equivalent of 1,3 propanediamine provided a bis imine intermediate, which was reduced with sodium borohydride to get the meso and d,I diastereoisomers of HM-PAO. Separation of these was achieved by fractional crystallization. {sup 99m} Tc-(d,I)HM-PAO was obtained by stannous ion reduction of Mo-99/Tc-99m generator eluate in the presence of the ligand. Complex radiochemical purity was determined by instant thin layer chromatography and paper chromatography. Finally, we obtained {sup 99m} Tc-(d,I)HM-PAO with a high radiochemical yield, in excess of 90%. However, for subsequent clinical studies the preparation has to be done a few minutes before application because our product has a low stability. (Author)

  3. Theoretical study of C{sub 60} as catalyst for dehydrogenation in LiBH{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Scheicher, Ralph H; Araujo, C Moyses; Blomqvist, Andreas; Ahuja, Rajeev [Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Li, Sa; Jena, Puru, E-mail: ralph.scheicher@physics.uu.se [Physics Department, Virginia Commonwealth University, Richmond, VA 23284 (United States)

    2011-08-19

    Complex light metal hydrides possess many properties which make them attractive as a storage medium for hydrogen, but typically catalysts are required to lower the hydrogen desorption temperature and to facilitate hydrogen uptake in the form of a reversible reaction. The overwhelming focus in the search for catalysing agents has been on compounds containing titanium, but the precise mechanism of their actions remains somewhat obscure. A recent experiment has now shown that fullerenes (C{sub 60}) can also act as catalysts for both hydrogen uptake and release in lithium borohydride (LiBH{sub 4}). In an effort to understand the involved mechanism, we have employed density functional theory to carry out a detailed study of the interaction between this complex metal hydride and the carbon nanomaterial. Considering a stepwise reduction of the hydrogen content in LiBH{sub 4}, we find that the presence of C{sub 60} can lead to a substantial reduction of the involved H-removal energies. This effect is explained as a consequence of the interaction between the BH{sub x}{sup -} complex and the C{sub 60} entity.

  4. Facile synthesis of near-monodisperse Ag-Ni core-shell nanoparticles and their application for catalytic generation of hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Guo Huizhang; Chen Yuanzhi; Chen Xiaozhen; Wen Ruitao; Yue Guanghui; Peng Dongliang, E-mail: yuanzhi@xmu.edu.cn, E-mail: dlpeng@xmu.edu.cn [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China)

    2011-05-13

    Magnetically recyclable Ag-Ni core-shell nanoparticles have been fabricated via a simple one-pot synthetic route using oleylamine both as solvent and reducing agent and triphenylphosphine as a surfactant. As characterized by transmission electron microscopy (TEM), the as-synthesized Ag-Ni core-shell nanoparticles exhibit a very narrow size distribution with a typical size of 14.9 {+-} 1.2 nm and a tunable shell thickness. UV-vis absorption spectroscopy study shows that the formation of a Ni shell on Ag core can damp the surface plasmon resonance (SPR) of the Ag core and lead to a red-shifted SPR absorption peak. Magnetic measurement indicates that all the as-synthesized Ag-Ni core-shell nanoparticles are superparamagnetic at room temperature, and their blocking temperatures can be controlled by modulating the shell thickness. The as-synthesized Ag-Ni core-shell nanoparticles exhibit excellent catalytic properties for the generation of H{sub 2} from dehydrogenation of sodium borohydride in aqueous solutions. The hydrogen generation rate of Ag-Ni core-shell nanoparticles is found to be much higher than that of Ag and Ni nanoparticles of a similar size, and the calculated activation energy for hydrogen generation is lower than that of many bimetallic catalysts. The strategy employed here can also be extended to other noble-magnetic metal systems.

  5. Biogenic robust synthesis of silver nanoparticles using Punica granatum peel and its application as a green catalyst for the reduction of an anthropogenic pollutant 4-nitrophenol

    Science.gov (United States)

    Edison, T. Jebakumar Immanuel; Sethuraman, M. G.

    2013-03-01

    A robust synthesis of silver nanoparticles (AgNPs) using the peel extract of Punica granatum is reported in this article. The formation of AgNPs was confirmed by the appearance of brownish yellow color and the Surface Plasmon Resonance (SPR) peak at 432 nm. The biogenic AgNPs were found to have the size approximately 30 nm with distorted spherical shape. The high negative zeta potential values of AgNPs revealed their high stability which could be attributed to the capping of AgNPs by the phytoconstituents of the Punica granatum peel. The biogenic AgNPs were also found to function as an effective green catalyst in the reduction of anthropogenic pollutant viz., 4-nitrophenol (4-NP) by solid sodium borohydride, which was evident from the instantaneous color change of bright yellow (400 nm) to colorless (294 nm) solution, after the addition of AgNPs. The catalytic action of biogenic AgNPs in the reduction of 4-NP could be explained on the basis of Langmuir-Hinshelwood model.

  6. 2',3'-cyclic nucleotide-3'-phosphodiesterase in the central nervous system is fatty-acylated by thioester linkage.

    Science.gov (United States)

    Agrawal, H C; Sprinkle, T J; Agrawal, D

    1990-07-15

    2',3'-Cyclic nucleotide-3'-phosphodiesterase (CNP1 and CNP2 with Mr of 46,000 and 48,000, respectively) is the major enzyme of central nervous system myelin. It is associated with oligodendroglial plasma membrane and uncompacted myelin (myelin-like fraction), which are in contact with glial cytoplasm. Proteins of the myelin-like fraction were labeled with [3H]palmitic acid in brain slices from 17-day-old rats and immunoprecipitated with anti-CNP antiserum. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography of immunoprecipitated material revealed intense acylation of CNP1 and CNP2, and radioactivity was released by hydroxylamine. Palmitic acid was covalently bound to CNP because radioactivity was not removed by extraction of immunoprecipitated CNP with organic solvent or by boiling in sodium dodecyl sulfate and dithiothreitol. However, treatment of immunoprecipitated CNP with (a) hydroxylamine-released palmitohydroxamate and palmitic acid, (b) sodium borohydride-released hexadecanol, and (c) methanolic-KOH-released methyl palmitate. Synthesis, acylation, or transport of CNP was not affected by monensin or colchicine. However, acylation of CNP was inhibited 24-32% by cycloheximide. These results provide conclusive evidence that CNP1 and CNP2 are fatty acid acylated with palmitate through a thioester linkage and is posttranslationally modified sometime after synthesis. PMID:2164018

  7. Ag recovery from copper anode slime by acid leaching at atmospheric pressure to synthesize silver nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Atefeh Khaleghi; Sattar Ghader; Dariush Afzali

    2014-01-01

    In this paper, recovery of silver from anode slime of Sarcheshmeh copper complex in Iran and subsequent synthesis of silver nanoparticles from leaching solution is investigated. Sarcheshmeh anode slime is mainly consisted of Cu, Ag, Pb and Se. Amount of Ag in the considered anode slime was 5.4%(by weight). The goal was to recover as much as possible Ag from anode slime at atmospheric pressure to synthesize Ag nanoparticles. Therefore, acid leaching was used for this purpose. The anode slime was leached with sulfuric and nitric acid from room to 90 ?C at different acid concentrations and the run which yielded the most recovery of Ag was selected for Ag nanoparticles synthesis. At this condition, Cu, Pb and Se are lea-ched as well as Ag. To separate Ag from leach solution HCl was added and silver was precipitated as AgCl which were then dissolved by ammonia solution. The Ag nanoparticles are synthesized from this solution by chemical reduction method by aid of sodium borohydride in the presence of PVP and PEG as stabiliz-ers. The synthesized Ag nanoparticles showed a peak of 394 nm in UV-vis spectrum and TEM images showed a rather uniform Ag nanoparticles of 12 nm.

  8. Versatile synthesis of PHMB-stabilized silver nanoparticles and their significant stimulating effect on fodder beet (Beta vulgaris L.).

    Science.gov (United States)

    Gusev, Alexander А; Kudrinsky, Alexey A; Zakharova, Olga V; Klimov, Alexey I; Zherebin, Pavel M; Lisichkin, George V; Vasyukova, Inna A; Denisov, Albert N; Krutyakov, Yurii A

    2016-05-01

    Silver nanoparticles (AgNPs) are well-known bactericidal agents. However, information about the influence of AgNPs on the morphometric parameters and biochemical status of most important agricultural crops is limited. The present study reports the influence of AgNPs stabilized with cationic polymer polyhexamethylene biguanide hydrochloride (PHMB) on growth, development, and biochemical status of fodder beet Beta vulgaris L. under laboratory and greenhouse conditions. PHMB-stabilized AgNPs were obtained via sodium borohydride reduction of silver nitrate in an aqueous solution. The average diameter of thus prepared AgNPs was 10 nm. It appears that the results of experiments with laboratory-grown beets in the nanosilver-containing medium, where germination of seeds and growth of roots were suppressed, do not correlate with the results of greenhouse experiments. The observed growth-stimulating action of PHMB-stabilized AgNPs can be explained by the change of activity of oxidases and, consequently, by the change of auxins amount in plant tissues. In beets grown in the presence of PHMB-stabilized AgNPs no negative deviations of biological parameters from normal values were registered. Furthermore, the SEM/EDS examination revealed no presence of silver in the tissues of the studied plants. PMID:26952409

  9. Ag@Au core-shell dendrites: a stable, reusable and sensitive surface enhanced Raman scattering substrate

    Science.gov (United States)

    Jun Yin, Hong; Yang Chen, Zhao; Mei Zhao, Yong; Yang Lv, Ming; An Shi, Chun; Long Wu, Zheng; Zhang, Xin; Liu, Luo; Li Wang, Ming; Jun Xu, Hai

    2015-09-01

    Surface enhanced Raman scattering (SERS) substrate based on fabricated Ag@Au core-shell dendrite was achieved. Ag dendrites were grown on Si wafer by the hydrothermal corrosion method and Au nanofilm on the surface of Ag dendritic nanostructure was then fabricated by chemical reduction. With the help of sodium borohydride in water, Au surface absorbates such as thiophene, adenine, rhodamine, small anions (Br- and I-), and a polymer (PVP, poly(N-vinylpyrrolidone)) can be completely and rapidly removed. After four repeatable experiments, the substrate SERS function did not decrease at all, indicating that the Ag@Au dendrite should be of great significance to SERS application because it can save much resource. Six-month-duration stability tests showed that the Ag@Au core-shell dendrite substrate is much more stable than the Ag dendrite substrates. We have also experimented on fast detection of Cd2+ at 10-8  M concentration by decorating single-stranded DNA containing adenine and guanine bases on the surface of this Ag@Au dendrite. Finite-difference time-domain simulations were carried out to investigate the influence of Au nanolayer on Ag dendrites, which showed that the local electric fields and enhancement factor are hardly affected when a 4 nm Au nanolayer is coated on Ag dendrite surface.

  10. Histochemical and structural analysis of mucous glycoprotein secreted by the gill of Mytilus edulis

    International Nuclear Information System (INIS)

    Studies were carried out to characterized various mucous cells in the gill filament, to ascertain structural characteristics of the secreted mucous glycoproteins, and to determine the ability of the gill epithelium to incorporate [14C]glucosamine as a precursor in the biosynthesis and secretion of mucous glycoproteins. Using histochemical staining techniques, mucous cells containing neutral and acidic mucins were found in the lateral region, whereas mucous cells containing primarily neutral or sulfated mucins were found in the postlateral region. Serotonin, but not dopamine, stimulated the mucous secretion. In tissues pretreated with [14C]glucosamine, the secreted glycoproteins contain incorporated radiolabel. Analysis by column chromatography using Bio-Gel P-2 and P-6 shows that the secretion contains two glycoprotein populations. Glycoprotein II has a molecular weight of 2.3 x 104 daltons. Upon alkaline reductive borohydride cleavage of the O-glycosidic linkages of glycoprotein I, about 70% of the radiolabel was removed from the protein. Gas chromatographic analysis of the carbohydrate composition shows that the glycoproteins contains N-acetylglucosamine (GluNAc), N-acetylgalactosamine (GalNAc), and galactose, fucose and mannose. Amino acid analysis shows that the glycoproteins are rich in serine, threonine and proline

  11. Determination of copper, molybdenum and selenium in biological reference materials by inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    In a contribution to the elemental characterization of 10 new reference materials, Bovine Muscle Powder (136), Corn Starch (162), Hard Red Spring Wheat Flour (165), Soft Winter Wheat Flour (166), Whole Milk Powder (183), Wheat Gluten (184), Corn Bran (186). Durum Wheat Flour (187), Whole Egg Powder (188) and Microcrystalline Cellulose (189), the total concentrations of Cu, Mo and Se were determined by the application of an analytical method based on isotope dilution inductively coupled plasma mass spectrometry. Cu and Mo contents were quantified by measurement of 65Cu/63Cu and 97Mo/100Mo isotopic ratios following spiking with 65Cu and 97Mo and digestion with nitric acid. Selenium was separated as hydrogen selenide from the matrix using sodium borohydride after spiking with 82Se and acid digestion-dry ashing and quantified by measurement of the 82Se/78Se isotopic ratio. Comparison of these results with those from a variety of other methods and assessment of the procedures using certified reference materials indicated that the determinations of Cu, Mo and Se were performed without analytical bias. (orig.)

  12. Ground and excited state behavior of 1,4-dimethoxy-3-methyl-anthracene-9,10-dione in silver nanoparticles: Spectral and computational investigations

    Energy Technology Data Exchange (ETDEWEB)

    Umadevi, M., E-mail: ums10@yahoo.com [Department of Physics, Mother Teresa Women' s University, Kodaikanal 624101, Tamil Nadu (India); Kavitha, S.R. [Department of Physics, Mother Teresa Women' s University, Kodaikanal 624101, Tamil Nadu (India); Vanelle, P.; Terme, T.; Khoumeri, O. [Laboratoire de Pharmaco-Chimie Radicalaire, Faculté de Pharmacie, Aix-Marseille Univ, CNRS, Institut de Chimie Radicalaire ICR, UMR 7273, 27 Boulevard Jean Moulin, 13385 Marseille Cedex 05 (France)

    2013-10-15

    Silver nanoparticles (Ag NPs) of various sizes have been successfully synthesized by the simple and convenient Creighton method using sodium borohydride as the reducing agent under microwave irradiation. Optical absorption and fluorescence emission spectroscopic techniques were employed to investigate the effect of silver nanoparticles on the ground and excited state of 1,4-dimethoxy-3-methylanthracene-9,10-dione (DMMAD). The surface plasmon resonance (SPR) peak of the prepared silver colloidal solution was observed at 400 nm. Fluorescence quenching of DMMAD by silver nanoparticles has been found to increase with increase in the size of Ag. The fluorescence quenching has been explained by Forster Resonance Energy Transfer (FRET) theory between DMMAD and silver nanoparticles. The Stern–Volmer quenching constant and Benesi–Hildebrand association constant for the above system were calculated. DFT calculations were also performed to study the charge distribution of DMMAD in Ag both in ground and excited states. -- Highlights: • Silver nanoparticles (Ag NPs) have been synthesized using the Creighton method. • Effect of Ag NPs on the ground state of DMMAD was studied. • Influence of Ag NPs on the excited state of DMMAD was investigated. • Fluorescence quenching has been explained by Forster Resonance Energy Transfer. • Quenching and binding constants were also calculated.

  13. RAPID DEGRADATION OF AZO DYES USING NANO-SCALE ZERO VALENT IRON

    Directory of Open Access Journals (Sweden)

    Nabila Rahman

    2014-01-01

    Full Text Available In the present study, nano-scale Zero Valent Iron (NZVI was synthesized in ethanol medium by the method of ferric iron reduction using sodium borohydride as a reducing agent under atmospheric conditions. The obtained iron nanoparticles are mainly in zero valent oxidation state and remain without significant oxidation for hours. A systematic characterization of NZVI was performed using XRD, SEM and TEM studies. The obtained iron nanoparticles consist of a zero valent core surrounding a rest oxide shell. The diameter of iron nanoparticles was predominantly within the range 20-110 nm. Refractory azo-dye compounds used in the textile industry are commonly detected in many industrial waste water. In this study the removal efficiency of three azo dyes, namely, methyl orange, sunset yellow and acid blue a, with laboratory synthesized NZVI particles in relation to the NZVI dosage, dye concentration and pH was determined. Increasing the dose of NZVI particles enhanced the decolonization of the dyes. The degradation decreased with increasing solution pH and concentration of dyes. These findings demonstrated the fast removal of azo dye compounds with NZVI and the advantage of the synthesized NZVI particles to treat azo dye contaminated wastewater.

  14. High-Efficiency Palladium Nanoparticles Supported on Hydroxypropyl-β-Cyclodextrin Modified Fullerene [60] for Ethanol Oxidation

    International Nuclear Information System (INIS)

    Highlights: • C60 support provides new ways to develop catalyst materials for its distorted structure. • Pd nanoparticles with uniform size and high dispersion have been successfully assembled on HP-β-CD-C60 in aqueous solution. • Pd/HP-β-CD-C60 shows very promising catalytic activity for ethanol oxidation. - Abstract: In this paper, Palladium nanoparticles with uniform size and high dispersion have been successfully assembled on hydroxypropyl-β-Cyclodextrin (HP-β-CD) modified C60 (abbreviated as HP-β-CD-C60) via a sodium borohydride reduction process. According to the transmission electron microscopy (TEM) measurements, the average particle size of the as-prepared Pd nanoparticles dispersed on HP-β-CD modified C60 is 2.7 nm. Electrochemical studies reveal that the Pd/HP-β-CD-C60 modified electrode shows a significantly high electrocatalytic activity, much more negative onset potentials and better stability than electrodes modified by other electrocatalysts for ethanol oxidation, which indicates that it is a better potential candidate for application in a direct ethanol fuel cell (DEFC)

  15. Biomimetic synthesis of silver nanoparticles using the fish scales of Labeo rohita and their application as catalysts for the reduction of aromatic nitro compounds.

    Science.gov (United States)

    Sinha, Tanur; Ahmaruzzaman, M; Sil, A K; Bhattacharjee, Archita

    2014-10-15

    In this article, a cleaner, greener, cheaper and environment friendly method for the generation of self assembled silver nanoparticles (Ag NPs) applying a simple irradiation technique using the aqueous extract of the fish scales (which is considered as a waste material) of Labeo rohita is described. Gelatin is considered as the major ingredient responsible for the reduction as well as stabilisation of the self assembled Ag NPs. The size and morphology of the individual Ag NPs can be tuned by controlling the various reaction parameters, such as temperature, concentration, and pH. Studies showed that on increasing concentration and pH Ag NPs size decreases, while on increasing temperature, Ag NPs size increases. The present process does not need any external reducing agent, like sodium borohydride or hydrazine or others and gelatin itself can play a dual role: a 'reducing agent' and 'stabilisation agent' for the formation of gelatin-Ag NPs colloidal dispersion. The synthesized Ag NPs were characterised by Ultraviolet-Visible spectroscopy (UV-Vis), Transmission electron microscopy (TEM) and Selected area electron diffraction (SAED) analyses. The synthesized Ag NPs was used to study the catalytic reduction of various aromatic nitro compounds in aqueous and three different micellar media. The hydrophobic and electrostatic interaction between the micelle and the substrate is responsible for the catalytic activity of the nanoparticles in micelle.

  16. Preparation, characterization, and antibacterial activity studies of silver-loaded poly(styrene-co-acrylic acid) nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Song, Cunfeng [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Chang, Ying; Cheng, Ling; Xu, Yiting [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Chen, Xiaoling, E-mail: tinachen0628@163.com [Department of Endodontics, Xiamen Stomatology Hospital, Teaching Hospital of Fujian Medical University, Xiamen 361003 (China); Zhang, Long; Zhong, Lina [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Dai, Lizong, E-mail: lzdai@xmu.edu.cn [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China)

    2014-03-01

    A simple method for preparing a new type of stable antibacterial agent was presented. Monodisperse poly(styrene-co-acrylic acid) (PSA) nanospheres, serving as matrices, were synthesized via soap-free emulsion polymerization. Field-emission scanning electron microscopy micrographs indicated that PSA nanospheres have interesting surface microstructures and well-controlled particle size distributions. Silver-loaded poly(styrene-co-acrylic acid) (PSA/Ag-NPs) nanocomposites were prepared in situ through interfacial reduction of silver nitrate with sodium borohydride, and further characterized by transmission electron microscopy and X-ray diffraction. Their effects on antibacterial activity including inhibition zone, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and bactericidal kinetics were evaluated. In the tests, PSA/Ag-NPs nanocomposites showed excellent antibacterial activity against both gram-positive Staphylococcus aureus and gram-negative Escherichia coli. These nanocomposites are considered to have potential application in antibacterial coatings on biomedical devices to reduce nosocomial infection rates. - Highlights: • A new type of antibacterial agent (PSA/Ag-NPs nanocomposites) was synthesized. • The antibacterial activity against S. aureus and E. coli was studied. • Inhibition zone, MIC, MBC, and bactericidal kinetics were evaluated. • PSA/Ag-NPs nanocomposites showed excellent antibacterial activity.

  17. FACILE GREEN SYNTHESIS OF GOLD NANOPARTICLES WITH GREAT CATALYTIC ACTIVITY USING ULVA FASCIATA

    Directory of Open Access Journals (Sweden)

    V. Sugantha Kumari

    2014-03-01

    Full Text Available We report a facile, green, and high yielding approache for the synthesis and stabilization of monodisperse gold nanoparticles (AuNPs using green seaweed Ulva fasciata extract. Characterization of the obtained AuNPs was performed using UV-visible, Fourier transform infrared (FTIR, X-ray diffraction (XRD and transmission electron microscopy (TEM. UV-visible absorption spectroscopy was used to determine the yield of the gold nanoparticles. The UV-visible absorption spectrum showed a characteristic optical peak of AuNPs at 541 nm. The X-ray diffraction pattern suggested the formation and crystallinity of AuNPs. Spherical AuNPs synthesized with an average particle size of 10 ± 3 nm were confirmed by TEM. FTIR analysis supported the role of phytochemicals of Ulva fasciata extract for bioreduction and stabilization of AuNPs. Moreover, the synthesized AuNPs exhibit remarkable catalytic efficiency by using the reduction of 4-nitroaniline by potassium borohydride in aqueous solution using UV-visible absorption spectroscopy. Catalytic reduction followed pseudo-first-order kinetics with respect to 4-Nitrophenol.

  18. Study of Methylene Blue Degradation by Gold Nanoparticles Synthesized within Natural Zeolites

    Directory of Open Access Journals (Sweden)

    Ericka Rodríguez León

    2016-01-01

    Full Text Available We carried out the in situ synthesis of gold nanoparticles inside a natural clinoptilolite-type zeolite matrix, using ascorbic acid as reducing agent. The microstructure of both zeolite and zeolite-gold nanocomposite was characterized by X-ray diffraction (XRD, Scanning Electron Microscopy (SEM, Scanning Transmission Electron Microscopy (STEM, and Energy-Dispersive X-ray Spectroscopy (EDS techniques. Size distribution as assessed by STEM indicated that 60% of gold nanoparticles measured less than 2.5 nm. Determination of the surface area by the BET method revealed a specific value of 27.35 m2/g. The catalytic activity of zeolite-gold regarding methylene blue degradation under different light-exposing conditions was evaluated by UV-Vis spectroscopy. The results indicated that 50% degradation was achieved in only 11 min in presence of sunlight. This reaction was faster in comparison with those obtained using a white LED light. A notable aspect of this study is that catalysis was carried out without the addition of any strong reducing agents, such as sodium borohydride (NaBH4.

  19. Characterization of natural zeolite clinoptilolite for sorption of contaminants

    Science.gov (United States)

    Xingu-Contreras, E.; García-Rosales, G.; García-Sosa, I.; Cabral-Prieto, A.; Solache-Ríos, M.

    2015-06-01

    The nanoparticles technology has received considerable attention for its potential applications in groundwater treatment for the removal of various pollutants as Cadmium. In this work, iron boride nanoparticles were synthesized in pure form and in presence of homo-ionized zeolite clinoptilolite, as support material. These materials were used for removing Cd (II) from aqueous solutions containing 10, 50, 100, 150, 200, 250, 300 and 400 mg/L. The characterization of these materials was made by using X-ray Diffraction, Scanning Electron Microscopy and Mössbauer Spectroscopy. Pure iron boride particles show a broad X-ray diffraction peak centered at 45∘ (2 𝜃), inferring the presence of nanocrystals of Fe2B as identified from Mössbauer Spectroscopy. The size of these Fe2B particles was within the range of 50 and 120 nm. The maximum sorption capacities for Cd (II) of iron boride particles and supported iron boride particles in homo-ionized zeolitic material were nearly 100 %. For homo-ionized zeolite and homo-ionized zeolite plus sodium borohydride was ≥ 95 %.

  20. Characterization of natural zeolite clinoptilolite for sorption of contaminants

    International Nuclear Information System (INIS)

    The nanoparticles technology has received considerable attention for its potential applications in groundwater treatment for the removal of various pollutants as Cadmium. In this work, iron boride nanoparticles were synthesized in pure form and in presence of homo-ionized zeolite clinoptilolite, as support material. These materials were used for removing Cd (II) from aqueous solutions containing 10, 50, 100, 150, 200, 250, 300 and 400 mg/L. The characterization of these materials was made by using X-ray Diffraction, Scanning Electron Microscopy and Mössbauer Spectroscopy. Pure iron boride particles show a broad X-ray diffraction peak centered at 45∘ (2θ), inferring the presence of nanocrystals of Fe2B as identified from Mössbauer Spectroscopy. The size of these Fe2B particles was within the range of 50 and 120 nm. The maximum sorption capacities for Cd (II) of iron boride particles and supported iron boride particles in homo-ionized zeolitic material were nearly 100 %. For homo-ionized zeolite and homo-ionized zeolite plus sodium borohydride was ≥ 95 %

  1. Three-dimensional cellulose sponge: Fabrication, characterization, biomimetic mineralization, and in vitro cell infiltration.

    Science.gov (United States)

    Joshi, Mahesh Kumar; Pant, Hem Raj; Tiwari, Arjun Prasad; Maharjan, Bikendra; Liao, Nina; Kim, Han Joo; Park, Chan Hee; Kim, Cheol Sang

    2016-01-20

    In this study, cellulose based scaffolds were produced by electrospinning of cellulose acetate (CA) solution followed by its saponification with NaOH/ethanol system for 24h. The resulting nonwoven cellulose mat was treated with sodium borohydride (SB) solution. In situ hydrolysis of SB solution into the pores of the membrane produced hydrogen gas resulting a three-dimensional (3D) cellulose sponge. SEM images demonstrated an open porous and loosely packed fibrous mesh compared to the tightly packed single-layered structure of the conventional electrospun membrane. 3D cellulose sponge showed admirable ability to nucleate bioactive calcium phosphate (Ca-P) crystals in simulated body fluid (SBF) solution. SEM-EDX and X-ray diffraction studies revealed that the minerals deposited on the nanofibers have the nonstoichiometric composition similar to that of hydroxyapatite, the mineralized component of the bone. 3D cellulose sponge exhibited the better cell infiltration, spreading and proliferation compared to 2D cellulose mat. Therefore, a facile fabrication of 3D cellulose sponge with improved mineralization represents an innovative strategy for the bone tissue engineering applications.

  2. Electrochemistry of magnesium electrolytes in ionic liquids for secondary batteries.

    Science.gov (United States)

    Vardar, Gulin; Sleightholme, Alice E S; Naruse, Junichi; Hiramatsu, Hidehiko; Siegel, Donald J; Monroe, Charles W

    2014-10-22

    The electrochemistry of Mg salts in room-temperature ionic liquids (ILs) was studied using plating/stripping voltammetry to assess the viability of IL solvents for applications in secondary Mg batteries. Borohydride (BH4(-)), trifluoromethanesulfonate (TfO(-)), and bis(trifluoromethanesulfonyl)imide (Tf2N(-)) salts of Mg were investigated. Three ILs were considered: l-n-butyl-3-methylimidazolium (BMIM)-Tf2N, N-methyl-N-propylpiperidinium (PP13)-Tf2N, and N,N-diethyl-N-methyl(2-methoxyethyl)ammonium (DEME(+)) tetrafluoroborate (BF4(-)). Salts and ILs were combined to produce binary solutions in which the anions were structurally similar or identical, if possible. Contrary to some prior reports, no salt/IL combination appeared to facilitate reversible Mg plating. In solutions containing BMIM(+), oxidative activity near 0.8 V vs Mg/Mg(2+) is likely associated with the BMIM cation, rather than Mg stripping. The absence of voltammetric signatures of Mg plating from ILs with Tf2N(-) and BF4(-) suggests that strong Mg/anion Coulombic attraction inhibits electrodeposition. Cosolvent additions to Mg(Tf2N)2/PP13-Tf2N were explored but did not result in enhanced plating/stripping activity. The results highlight the need for IL solvents or cosolvent systems that promote Mg(2+) dissociation. PMID:25248147

  3. Design of Cobalt Nanoparticles with Tailored Structural and Morphological Properties via O/W and W/O Microemulsions and Their Deposition onto Silica

    Directory of Open Access Journals (Sweden)

    Gabriella Di Carlo

    2015-03-01

    Full Text Available Cobalt nanostructures with different size and morphology, i.e., spherical nanoparticles, nanorods, and particles arranged into elongated structures, were prepared using micelles and microemulsions as confined reaction media. The syntheses were carried out using three types of systems: aqueous surfactant solutions, oil-in water (O/W, and water-in-oil (W/O microemulsions. The influence of the surfactant and the precipitating agent used for synthesis was also investigated. For this purpose, cobalt nanostructures were prepared using different non-ionic surfactants, namely Synperonic® 10/6, Pluronic® P123 and a mixture of SPAN 20–TWEEN 80. Three different precipitating agents were used: sodium borohydride, sodium hydroxide, and oxalic acid. Our findings revealed that by changing the type of reaction media as well as the precipitating agent it is possible to modify the shape and size of the cobalt nanostructures. Moreover, the use of O/W microemulsion generates better results in terms of colloidal stability and uniformity of particle size with respect to W/O microemulsion. The different cobalt nanostructures were supported on commercial and mesoporous silica; transmission electron microscopy (TEM images showed that after deposition the Co nanocrystals remain well dispersed on the silica supports. This behavior suggests their great potential in catalytic applications.

  4. An analytical method for determination of mercury by cold vapor atomic absorption spectroscopy; Determinazione di mercurio. Metodo per spettrometria di assorbimento atomico a vapori freddi (CV-AAS)

    Energy Technology Data Exchange (ETDEWEB)

    Campanella, L. [Rome Univ. La Sapienza, Rome (Italy); Mastroianni, D.; Capri, S.; Pettine, M. [CNR, Rome (Italy). Ist. di Ricerca sulle Acque; Spezia, S.; Bettinelli, M. [ENEL, Unified Modelling Language, Piacenza (Italy)

    1999-09-01

    An analytical procedure for the determination of total mercury in wastewaters and natural waters is described. Aqueous samples are fast digested with nitric acid by using the microwave-oven technique; the analysis of mercury is then performed by cold vapor atomic absorption spectrometry (CV-AAS) using two possible instrumental apparatus (batch system or flow injection). Sodium borohydride is used as the reducing agent for mercury in solution (Method A). The use of amalgamation traps on gold for the preconcentration of mercury lowers the detection limit of the analyte (Method B). [Italian] Viene descritta una procedura analitica per la determinazione del mercurio totale in acque di scarico e naturali. Il campione acquoso viene sottoposto a mineralizzazione con acido nitrico in forno a microonde e analizzato mediante spettroscopia di assorbimento atomico a vapori freddi (CV-AAS) in due possibili configurazioni strumentali (sistema batch oppure flow injection), utilizzando sodio boro idruro come agente riducente del mercurio (metodo A). L'impiego della trappola di oro per la preconcentrazione del mercurio mediante amalgama consente di determinare l'analita a livelli di pochi ng/L (metodo B).

  5. Tin Content Determination in Canned Fruits and Vegetables by Hydride Generation Inductively Coupled Plasma Optical Emission Spectrometry

    Directory of Open Access Journals (Sweden)

    Sanda Rončević

    2012-01-01

    Full Text Available Tin content in samples of canned fruits and vegetables was determined by hydride generation inductively coupled plasma atomic emission spectrometry (HG-ICP-OES, and it was compared with results obtained by standard method of flame atomic absorption spectrometry (AAS. Selected tin emission lines intensity was measured in prepared samples after addition of tartaric acid and followed by hydride generation with sodium borohydride solution. The most favorable line at 189.991 nm showed the best detection limit (1.9 μg L−1 and limit of quantification (6.4 μg kg−1. Good linearity and sensitivity were established from time resolved analysis and calibration tests. Analytical accuracy of 98–102% was obtained by recovery study of spiked samples. Method of standard addition was applied for tin determination in samples from fully protected tinplate. Tin presence at low-concentration range was successfully determined. It was shown that tenth times less concentrations of Sn were present in protected cans than in nonprotected or partially protected tinplate.

  6. Poly(N-isopropylacrylamide-co-methacrylic acid microgel stabilized copper nanoparticles for catalytic reduction of nitrobenzene

    Directory of Open Access Journals (Sweden)

    Farooqi Zahoor H.

    2015-09-01

    Full Text Available Poly(N-isopropylacrylamide-co-methacrylic acid microgels [p(NIPAM-co-MAAc] were synthesized by precipitation polymerization of N-isopropylacrylamide and methacrylic acid in aqueous medium. These microgels were characterized by dynamic light scattering and Fourier transform infrared spectroscopy. These microgels were used as micro-reactors for in situ synthesis of copper nanoparticles using sodium borohydride (NaBH4 as reducing agent. The hybrid microgels were used as catalysts for the reduction of nitrobenzene in aqueous media. The reaction was performed with different concentrations of cat­alyst and reducing agent. A linear relationship was found between apparent rate constant (kapp and amount of catalyst. When the amount of catalyst was increased from 0.13 to 0.76 mg/mL then kapp was increased from 0.03 to 0.14 min-1. Activation parameters were also determined by performing reaction at two different temperatures. The catalytic process has been discussed in terms of energy of activation, enthalpy of activation and entropy of activation. The synthesized particles were found to be stable even after 14 weeks and showed catalytic activity for the reduction of nitrobenzene.

  7. Characterization of natural zeolite clinoptilolite for sorption of contaminants

    Energy Technology Data Exchange (ETDEWEB)

    Xingu-Contreras, E., E-mail: nyleve-18@hotmail.com; García-Rosales, G., E-mail: gegaromx@yahoo.com.mx [Instituto Tecnológico de Toluca (Mexico); García-Sosa, I., E-mail: irma.garcia@inin.gob.mx; Cabral-Prieto, A., E-mail: agustin.cabral@inin.gob.mx; Solache-Ríos, M., E-mail: marcos.solache@inin.gob.mx [Instituto Nacional de Investigaciones Nucleares, Departamento de Química (Mexico)

    2015-06-15

    The nanoparticles technology has received considerable attention for its potential applications in groundwater treatment for the removal of various pollutants as Cadmium. In this work, iron boride nanoparticles were synthesized in pure form and in presence of homo-ionized zeolite clinoptilolite, as support material. These materials were used for removing Cd (II) from aqueous solutions containing 10, 50, 100, 150, 200, 250, 300 and 400 mg/L. The characterization of these materials was made by using X-ray Diffraction, Scanning Electron Microscopy and Mössbauer Spectroscopy. Pure iron boride particles show a broad X-ray diffraction peak centered at 45{sup ∘} (2θ), inferring the presence of nanocrystals of Fe{sub 2}B as identified from Mössbauer Spectroscopy. The size of these Fe{sub 2}B particles was within the range of 50 and 120 nm. The maximum sorption capacities for Cd (II) of iron boride particles and supported iron boride particles in homo-ionized zeolitic material were nearly 100 %. For homo-ionized zeolite and homo-ionized zeolite plus sodium borohydride was ≥ 95 %.

  8. Importance of the terminal α-amino group of bradykinin and some kynins on capillary permeability increase

    International Nuclear Information System (INIS)

    A simple and reliable method is described for the quantitative evaluation of vascular permeability increase induced by vasoactive drugs with Evans blue labelled with iodine-125 or 131. By using this method the importance of α-amino group of bradykinin (Bk), kallidin (Kd) and methionyl-kallidin (Met-Kd) on the biological activity were studied after reacting the kinins with pyridoxal 5'-phosphate followed by reduction with sodium borohydride. Phosphopyridoxyl-kinins were formed leaving free the guanidino groups. Aminoacid analysis of phosphopyridoxyl-kinin showed that the efficiency of the reaction was extremely good in the blockage of α-amino groups [phosphopyridoxyl-bradikinin (PP-Bk) = 98,8%, phosphopyridoxyl-kallidin (PP-Kd) = 95,2%, phosphopyridoxyl-methionyl-kallidin (PP-Met-Kd) = 98,0%. Log dose-response curves were obtained for Bk, Kd, Met-Kd, acetyl-bradykinin (Ac-Bk), PP-Bk, PP-Kd and PP-Met-Kd and the relative potencies calculated through the Lineweaver-Burk plots. The relative potencies were: PP-Bk about 16% the activity of Bk, Ac-Bk about 31% the activity of Bk, PP-Kd about 17% the activity of Kd, PP-Met-Kd about 12% the activity of Met-Kd. The results show that the terminal α-amino group of kinins is important in the mechanisms of biological activity. (Author)

  9. Solvent effects on Pt-Ru/C catalyst for methanol electro-oxidation

    Institute of Scientific and Technical Information of China (English)

    Jinwei Chen; Chunping Jiang; Hui Lu; Lan Feng; Xin Yang; Liangqiong Li; Ruilin Wang

    2009-01-01

    Alloying degree,particle size and the level of dispersion are the key structural parameters of Pt-Ru/C catalyst in fuel cells. Solvent(s) used in the preparation process can affect the particle size and alloying degree of the object substance,which lead to a great positive impact on its properties. In this work,three types of solvents and their mixtures were used in preparation of the Pt-Ru/C catalysts by chemical reduction of metal precursors with sodium borohydride at room temperature. The structure of the catalysts was characterized by X-ray diffraction (XRD) and Transmission electron microscopy (TEM). The catalytic activity and stability for methanol electro-oxidation were studied by Cyclic Voltammetry (CV) and Chronoamperometry (CA). Pt-Ru/C catalyst prepared in H_2O or binary solvents of H_2O and isopropanol had large particle size and low alloying degree leading to low catalytic activity and less stability in methanol electro-oxidation. When tetrahydrofuran was added to the above solvent systems,Pt-Ru/C catalyst prepared had smaller particle size and higher alloying degree which resulted in better catalytic activity,lower onset and peak potentials,compared with the above catalysts. Moreover,the catalyst prepared in ternary solvents of isopropanol,water and tetrahydrofuran had the smallest particle size,and the high alloying degree and the dispersion kept unchanged. Therefore,this kind of catalyst showed the highest catalytic activity and good stability for methanol electro-oxidation.

  10. Cob(I)alamin reacts with sucralose to afford an alkylcobalamin: relevance to in vivo cobalamin and sucralose interaction.

    Science.gov (United States)

    Motwani, Hitesh V; Qiu, Shiran; Golding, Bernard T; Kylin, Henrik; Törnqvist, Margareta

    2011-04-01

    Vitamin B(12), viz., cyano- or hydroxo-cobalamin, can be chemically or enzymatically converted into the derivatives methyl- and adenosyl-cobalamin, which are complex organometallic cofactors associated with several cobalamin-dependent enzymes. The reduced form of vitamin B(12), cob(I)alamin {Cbl(I)}, obtained by reduction of hydroxocobalamin (OH-Cbl) with e.g. sodium borohydride, is one of the most powerful nucleophiles known. Cbl(I) was shown to react readily with the synthetic sweetener sucralose (1,6-dichloro-1,6-dideoxy-β-D-fructofuranosyl-4-chloro-4-deoxy-α-D-galactopyranoside) in an aqueous system to form an alkylcobalamin (Suc-Cbl). This occurred by replacement of one of the three chlorine atoms of sucralose with a cobalamin moiety. The efficiency of trapping sucralose in presence of excess Cbl(I) was estimated to be >90%. Furthermore, in an in vitro study using human liver S9 with NADPH regeneration, in presence of OH-Cbl and sucralose, Suc-Cbl was shown to be formed. The Suc-Cbl was characterized primarily by LC-ESI(+)-MS/MS. Given the human consumption of sucralose from food and beverages, such a reaction between the sweetener and reduced vitamin B(12) could occur in vivo. PMID:21130828

  11. Facile synthesis of pentacle gold-copper alloy nanocrystals and their plasmonic and catalytic properties

    Science.gov (United States)

    He, Rong; Wang, You-Cheng; Wang, Xiaoyong; Wang, Zhantong; Liu, Gang; Zhou, Wei; Wen, Longping; Li, Qunxiang; Wang, Xiaoping; Chen, Xiaoyuan; Zeng, Jie; Hou, J. G.

    2014-07-01

    The combination of gold and copper is a good way to pull down the cost of gold and ameliorate the instability of copper. Through shape control, the synergy of these two metals can be better exploited. Here, we report an aqueous phase route to the synthesis of pentacle gold-copper alloy nanocrystals with fivefold twinning, the size of which can be tuned in the range from 45 to 200 nm. The growth is found to start from a decahedral core, followed by protrusion of branches along twinning planes. Pentacle products display strong localized surface plasmon resonance peaks in the near-infrared region. Under irradiation by an 808-nm laser, 70-nm pentacle nanocrystals exhibit a notable photothermal effect to kill 4T1 murine breast tumours established on BALB/c mice. In addition, 70-nm pentacle nanocrystals show better catalytic activity than conventional citrate-coated 5-nm Au nanoparticles towards the reduction of p-nitrophenol to p-aminophenol by sodium borohydride.

  12. Improved process for the synthesis of [2,2]-paracyclophane

    Science.gov (United States)

    Zhang, Long; Wang, Juan; Gao, Leng; Xu, Yulun; Gao, Weimin

    2006-01-01

    An improved method for the preparation of [2,2]-paracyclophane, which is the monomer of poly-p-xylene widely used as high quality electrical coating material, by Hoffmann elimination employing p-methyl-benzyl chloride and trimethyl amine as main raw materials was developed. Influence of solvent, reaction time, reaction temperature etal on the yield of paracyclophane was investigated experimentally. Suitable reaction parameters were obtained as follows: n(Alkali) : n(Quaternary ammonium) is 5:1; catalyst: 0.2% cupric salt; with 1,4-dioxane as solvent and 0.2% sodium borohydride as reducer, and N II as protection gas; reaction temperature 110°C, reaction time is 30 hr, at the condition, the yield of [2,2]-paracyclophane is 78.6%, its purity is over 99.5%, with melting point 284-285°C. Analysis results by IR and melting temperature measurement etal identify the substance synthesized is [2,2]-paracyclophane. And the materials used is industrially available and better yield was obtained comparing with the values present in the patent literatures.

  13. 苯叉丙酮缩胺化合物及其配合物的合成与表征%Synthesis and Characterization Study of Benzylidene Acetone Condensation Amine and Coordination Complexes

    Institute of Scientific and Technical Information of China (English)

    李章; 李淼; 李洪东; 戚峰; 滕云霞; 周徐亮; 王寿武

    2014-01-01

    利用乙二胺和亚苄基丙酮反应合成了不饱和化合物(Ph2Me2[14]dieneN4),再用硼氢化钾与不饱和化合物还原生成饱和的十四元大环化合物(Ph2Me2[14]H2dieneN4),并用盐酸和氢氧化钠对饱和十四元大环进行提纯,得到纯的十四元大环希夫碱并与乙酸酮反应生成配合物,通过红外光谱进行了表征。%The unsaturated Ph2Me2[14]dieneN4( Ⅱ ) compound was formed by ethylene diamine and benzylidene ketones reaction, then the unsaturated Ph2Me2[14]dieneN4( Ⅱ ) was reduced to the saturated fourteen macrocyclic compound Ph2Me2[14] H2dienenN4( Ⅲ ) by potassium borohydride. The saturated fourteen macrocyclic compound was purified with hydrochloric acid and sodium hydroxide. The copper complex was synthesized by this fourteen macrocyclic compound and copper acetate. The title complex was characterized by infrared spectroscopy.

  14. Preparation and electrochemical characterization of polyaniline functionalized copper bridges carbon nanotube for supercapacitor applications.

    Science.gov (United States)

    Giri, Soumen; Das, Chapal Kumar

    2014-08-01

    Supercapacitor is an alternative power source due to its high energy density, fast charge/discharge time, low level of heating, safety, long-term operation stability. MWCNTs are used for supercapacitor applications due to their unique properties, structure, high surface area. In the present work nanocomposites were prepared from Cu modified MWCNTs (binary) from which ternary composite also prepared with HCI doped polyaniline (PANI). Cu modified MWCNTs were prepared by the reduction of copper sulphate with sodium borohydride in basic medium. The uniform coating of polymer, upon the Cu modified MWCNTs, was evidenced from the field emission scanning electron microscopic (FESEM) and high resolution transmission electron microscopic (HRTEM) images. The modification of MWCNTs with Cu, was confirmed from the X-ray Diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. Cyclic voltammetry (CV) measurement and charge discharge test shows higher capacitance for the ternary composites (264 F/g) compared to the binary system (125 F/g). The cyclic stability and retention of specific capacitance also shows the better result for ternary system. PMID:25936120

  15. Gold and graphific carbon nitride hybrid plasmonic nanocomposites for photocatalytic reduction of 4-nitrophenol and 4-nitrobenzenethiol

    Science.gov (United States)

    Yan, Jiao; Xiao, Yuli; Liang, Xiu; Yang, Nan; Zhao, Dongyu; Yin, Penggang

    2016-09-01

    Gold nanoparticles (GNPs) were deposited on the surface of graphitic carbon nitride (g-C3N4) via an in situ reduction method using either sodium borohydride or trisodium citrate as the reducing agent. The corresponding hybrid Au/C3N4 nanocatalysts, viz., Au@CN-B or Au@CN-C, exhibited high light-driven catalytic activities toward reduction of 4-nitrophenol (4-NP) under either visible-light or ultra violet (UV) irradiation. The photocatalytic efficiency of Au@CN-B was only slightly higher than that of Au@CN-C, most likely owing to the average grain size difference between the both. However, as for plasmon-driven catalytic reactions monitored by surface-enhanced Raman scattering (SERS) technique, an immediate and almost-complete reduction of 4-nitrobenzenethiol (4-NBT) to p,p‧-dimercaptoazobenzene (DMAB) occurred when Au@CN-B was utilized as both the nanocatalyst and SERS substrate, whereas distinct characteristic peaks of 4-NBT still existed for the case of Au@CN-C.

  16. Preparation of spherical and cubic Fe{sub 55}Co{sub 45} microstructures for studying the role of particle morphology in magnetorheological suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Arief, Injamamul; Mukhopadhyay, P.K., E-mail: pkm@bose.res.in

    2014-06-01

    Cubic and spherical Fe{sub 55}Co{sub 45} alloyed microstructures were synthesized by borohydride reduction from aqueous solutions of metallic precursors, using stabilizers and polymer. Monosodium citrate, sodium acetate and PEG 6000 were utilized as electrostatic stabilizers and polymeric surface modifier. Suitable reaction conditions were maintained for synthesis of predominantly larger particles (0.7 µm to 1.2 µm), that facilitates use in magnetorheological fluids. Surface morphological studies by scanning electron microscopy revealed well shaped cubic and spherical geometry for the citrate and polymer-stabilized Fe{sub 55}Co{sub 45} alloys, while the alloy compositions remained nearly the same for both. X-ray diffractions of the as-prepared and annealed samples under various temperatures showed high degree of crystallinity with increasing temperatures. Studies of D.C. magnetization of the systems reveal that the particles have a core–shell structure, with inner magnetic core having a diameter around 30 nm with a log-normal distribution. Magnetorheological studies were performed with 8 vol% suspensions of as-synthesized particles dispersed in silicone oil (viscosity 30 mPa s at 25 °C) under different magnetic fields. Detailed studies of the magnetorheological properties were studied on these systems for practical use.

  17. Phytotoxicity of Ag nanoparticles prepared by biogenic and chemical methods

    Science.gov (United States)

    Choudhury, Rupasree; Majumder, Manna; Roy, Dijendra Nath; Basumallick, Srijita; Misra, Tarun Kumar

    2016-06-01

    Silver nanoparticles (Ag NPs) are now widely used as antibacterial and antifungal materials in different consumer products. We report here the preparation of Ag NPs by neem leaves extract ( Azadirachta) reduction and trisodium citrate-sodium borohydride reduction methods, and study of their phytotoxicity. The nanoparticles were characterized by UV-Vis spectroscopy, FTIR, and atomic force microscopy (AFM) techniques. Both neem-coated and citrate-coated Ag NPs exhibit surface plasmon around 400 nm, and their average sizes measured by AFM are about 100 and 20 nm, respectively. Antibacterial and antifungal activities of these nanomaterials have been studied by simple pea seed germination and disk diffusion methods. It has been observed from the growth of root and shoot, citrate-coated Ag NPs significantly affect seedling growth, but neem-coated Ag NPs exhibit somehow mild toxicity toward germination process due to the nutrient supplements from neem. On the other hand, antifungal activity of neem-coated Ag NPs has been found much higher than that of citrate-coated Ag NPs due to the combined effects of antifungal activity of neem and Ag NPs. Present research primarily indicates a possible application of neem-coated Ag NPs as a potential fungicide.

  18. Eco-friendly synthesis of silver and gold nanoparticles with enhanced bactericidal activity and study of silver catalyzed reduction of 4-nitrophenol

    Science.gov (United States)

    Naraginti, Saraschandra; Sivakumar, A.

    2014-07-01

    The present study reports a simple and robust method for synthesis of silver and gold nanoparticles using Coleus forskohlii root extract as reducing and stabilizing agent. Stable silver nanoparticles (AgNPs) and gold nanopoarticles (AuNPs) were formed on treatment of an aqueous silver nitrate (AgNO3) and chloroauric acid (HAuCl4) solutions with the root extract. The nanoparticles obtained were characterized by UV-Visible spectroscopy, Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). UV-Vis and TEM analysis indicate that with higher quantities of root extract, the interaction is enhanced leading to size reduction of spherical metal nanoparticles. XRD confirms face-centered cubic phase and the diffraction peaks can be attributed to (1 1 1), (2 0 0), (2 2 2) and (3 1 1) planes for these nanoparticles. These synthesized Ag and Au nanoparticles were found to exhibit excellent bactericidal activity against clinically isolated selected pathogens such as Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus). The synthesized AgNPs were also found to function as an efficient green catalyst in the reduction of anthropogenic pollutant 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by sodium borohydride, which was apparent from the periodical color change from bright yellow to colorless, after the addition of AgNPs.

  19. Attachment of noble metal nanoparticles to conducting polymers containing sulphur - preparation conditions for enhanced electrocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, V.C. [CQB, Departamento de Quimica e Bioquimica, Faculdade de Ciencias da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa (Portugal); CIQ-UP, Linha 4, Departamento de Quimica, Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Melato, A.I. [CQB, Departamento de Quimica e Bioquimica, Faculdade de Ciencias da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa (Portugal); Silva, A.F. [CIQ-UP, Linha 4, Departamento de Quimica, Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Abrantes, L.M., E-mail: luisa.abrantes@fc.ul.p [CQB, Departamento de Quimica e Bioquimica, Faculdade de Ciencias da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa (Portugal)

    2011-04-01

    Taking advantage of the spontaneous deposition of noble metals on polymers containing sulphur, the inclusion of gold and platinum in poly(3-methylthiophene) and poly(3,4-ehylenedioxythiophene) (PEDOTh) layers, achieved by immersion of the polymer into the metal nanoparticles suspension, is reported in the present work. Platinum and gold nanoparticles (NPs), with diameters between 3 and 17 nm, have been prepared from colloidal methods (citrate or borohydride reduction in the presence of citrate capping agent) and characterized by transmission electron microscopy, ultraviolet-visible spectrophotometry and X-ray diffraction (XRD). The electropolymerization was carried out under potentiostatic and potentiodynamic conditions, imparting distinct morphologies, as revealed by atomic force microscopy. After polymer films immersion in the colloidal solutions, evidence of the NPs confinement and distribution was provided by XRD analysis and scanning electron microscopy. For thin layers, the quantity of attached metal NPs could be estimated from quartz crystal microbalance data collected throughout the films immersion.The influence of the polymer type and morphology, NPs nature, size and incorporated amount on the electrocatalytic activity of the so-prepared modified electrodes towards the hydrazine oxidation, in phosphate buffer solution, has been investigated by cyclic voltammetry. The results clearly show the superior properties of potentiodynamically prepared PEDOTh films attaching very small (3 nm) freshly prepared Pt-NPs.

  20. Electrochemical characterization of platinum-ruthenium nanoparticles prepared by water-in-oil microemulsion

    Energy Technology Data Exchange (ETDEWEB)

    Solla-Gullon, J.; Vidal-Iglesias, F.J.; Montiel, V.; Aldaz, A. [Universidad de Alicante (Spain). Instituto Universitario de Electroquimica, Departamento de Quimica-Fisica

    2004-11-01

    The synthesis, physical characterization, decontamination and some electrocatalytic properties of PtRu nanoparticles prepared using the microemulsion method are reported. The nanoparticles are synthesized by reduction with sodium borohydride of H{sub 2}PtCl{sub 6} and RuCl{sub 3} in a water-in-oil microemulsion of water/polyethylenglycol-dodecylether (BRIJ(Registered Trademark) 30)/n-heptane. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and energy dispersive analysis by X-rays (EDAX) experiments were carried out to characterize the single and bimetallic nanoparticles obtained. Cyclic voltammograms (CV) of clean nanoparticles were obtained after a controlled decontamination procedure of their surfaces. CO adsorption-oxidation and methanol electrooxidation were tested as test reactions to check the electrocatalytic behaviour of the bimetallic nanoparticles. Pt{sub 80}Ru{sub 20} (nominal atomic composition) nanoparticles are the best electrocatalyst for both CO{sub ad} and methanol oxidation. All these results show that the microemulsion method can be used to produce bimetallic nanoparticles in a very easy way. The method can be very easily scaled-up for industrial use. (author)

  1. The Enhanced Catalytic Activities of Asymmetric Au-Ni Nanoparticle Decorated Halloysite-Based Nanocomposite for the Degradation of Organic Dyes.

    Science.gov (United States)

    Jia, Lei; Zhou, Tao; Xu, Jun; Li, Xiaohui; Dong, Kun; Huang, Jiancui; Xu, Zhouqing

    2016-12-01

    Janus particles (JPs) are unique among the nano-/microobjects because they provide asymmetry and can thus impart drastically different chemical or physical properties. In this work, we have fabricated the magnetic halloysite nanotube (HNT)-based HNTs@Fe3O4 nanocomposite (NCs) and then anchored the Janus Au-Ni or isotropic Au nanoparticles (NPs) to the surface of external wall of sulfydryl modified magnetic nanotubes. The characterization by physical methods authenticates the successful fabrication of two different magnetic HNTs@Fe3O4@Au and HNTs@Fe3O4@Au-Ni NCs. The catalytic activity and recyclability of the two NCs have been evaluated considering the degradation of Congo red (CR) and 4-nitrophenol (4-NP) using sodium borohydride as a model reaction. The results reveal that the symmetric Au NPs participated NCs display low activity in the degradation of the above organic dyes. However, a detailed kinetic study demonstrates that the employ of bimetallic Janus Au-Ni NPs in the NCs indicates enhanced catalytic activity, owing to the structurally specific nature. Furthermore, the magnetic functional NCs reported here can be used as recyclable catalyst which can be recovered simply by magnet. PMID:26852228

  2. Novel Method for Indirect Determination of Iodine in Marine Products by Atomic Fluorescence Spectrometry

    Institute of Scientific and Technical Information of China (English)

    LU Jian-ping; TAN Fang-wei; TANG Qiong; JIANG Tian-cheng

    2013-01-01

    A method for the determination of iodine based upon compound H2HgI4,formed between I-and Hg2+ in nitric acid and extracted in methyl isobutyl ketone(MIBK),was developed via atomic fluorescence spectrometry(AFS).After the compound is reduced with potassium borohydrid(KBH4),the resultant mercury vapor was injected into the instrument and iodine was,therefore,indirectly determined.Experimental parameters such as the conditions of extraction reagents,aqueous phase acidity,elemental mercury diffusion temperature in a vial and other factors were investigated and optimized.Under the optimum experimental conditions,this method shows a detection limit of 0.038 μg/L iodine and a linear relationship between 0.04-20 μg/L.The method was applied to determining the iodine content in marine duck eggs,kelps,laver and Ganoderma lucidum spirulina,showing a relative standard deviation(RSD) of 2.15% and the recoveries in the range of 98.1%-102.5%.

  3. Generation of an ordered layer of silver nanoparticles in mesostructured dielectric films

    Energy Technology Data Exchange (ETDEWEB)

    Battie, Yann; Destouches, Nathalie, E-mail: destoucn@univ-st-etienne.f [Universite de Lyon (France); Bois, Laurence; Chassagneux, Fernand [Universite De Lyon, Laboratoire Multimateriaux et Interfaces UMR 5615 CNRS Universite Claude Bernard Lyon 1 (France); Moncoffre, Nathalie; Toulhoat, Nelly [Universite Lyon, IPNL, Universite de Lyon 1, CNRS/IN2P3 (France); Jamon, Damien [Universite de Lyon, Laboratoire DIOM EA 3526, Universite Jean Monnet (France); Ouerdane, Youcef [Universite de Lyon (France); Parola, Stephane [Universite De Lyon, Laboratoire Multimateriaux et Interfaces UMR 5615 CNRS Universite Claude Bernard Lyon 1 (France); Boukenter, Aziz [Universite de Lyon (France)

    2010-03-15

    Mesostructured organic-inorganic silica films containing AgNO{sub 3} are used as template to form ordered and dense layers of silver nanoparticles embedded in a dielectric matrix. The hybrid silica films are mesostructured by a triblock copolymer polyethylene oxide-polypropylene oxide-polyethylene oxide ((PEO){sub 106}(PPO){sub 70}(PEO){sub 106}, F127) and contain the silver precursor (AgNO{sub 3}) which is dissolved directly in the silica sol prior to deposition. The films are reacted with a sodium borohydride solution (NaBH{sub 4}), which leads to the formation of a plane ordered network of silver oblate nanoparticles with a narrow size distribution located just below the film surface, and observed by Transmission Electron Microscopy (TEM). The minor and major axis lengths are equal to 5.3 {+-} 0.5 and 7.2 {+-} 0.6 nm, respectively. The characterization of the mesostructured film before and after the reductive treatment evidences that silver particles grow in place of copolymer micelles in the upper layer of the mesostructured thin film. Rutherford Backscattering Spectrometry (RBS) measurements support the hypothesis that silver ions initially dispersed in the film volume migrate toward the film surface to form the monolayer of silver nanoparticles, organized and stabilized by the copolymer micelles in the film. IR and ellipsometric measurements are used to characterize the changes in the hybrid copolymer-silica matrix.

  4. Generation of an ordered layer of silver nanoparticles in mesostructured dielectric films

    International Nuclear Information System (INIS)

    Mesostructured organic-inorganic silica films containing AgNO3 are used as template to form ordered and dense layers of silver nanoparticles embedded in a dielectric matrix. The hybrid silica films are mesostructured by a triblock copolymer polyethylene oxide-polypropylene oxide-polyethylene oxide ((PEO)106(PPO)70(PEO)106, F127) and contain the silver precursor (AgNO3) which is dissolved directly in the silica sol prior to deposition. The films are reacted with a sodium borohydride solution (NaBH4), which leads to the formation of a plane ordered network of silver oblate nanoparticles with a narrow size distribution located just below the film surface, and observed by Transmission Electron Microscopy (TEM). The minor and major axis lengths are equal to 5.3 ± 0.5 and 7.2 ± 0.6 nm, respectively. The characterization of the mesostructured film before and after the reductive treatment evidences that silver particles grow in place of copolymer micelles in the upper layer of the mesostructured thin film. Rutherford Backscattering Spectrometry (RBS) measurements support the hypothesis that silver ions initially dispersed in the film volume migrate toward the film surface to form the monolayer of silver nanoparticles, organized and stabilized by the copolymer micelles in the film. IR and ellipsometric measurements are used to characterize the changes in the hybrid copolymer-silica matrix.

  5. Graphene Dendrimer-stabilized silver nanoparticles for detection of methimazole using Surface-enhanced Raman scattering with computational assignment

    Science.gov (United States)

    Saleh, Tawfik A.; Al-Shalalfeh, Mutasem M.; Al-Saadi, Abdulaziz A.

    2016-08-01

    Graphene functionalized with polyamidoamine dendrimer, decorated with silver nanoparticles (G-D-Ag), was synthesized and evaluated as a substrate with surface-enhanced Raman scattering (SERS) for methimazole (MTZ) detection. Sodium borohydride was used as a reducing agent to cultivate silver nanoparticles on the dendrimer. The obtained G-D-Ag was characterized by using UV-vis spectroscopy, scanning electron microscope (SEM), high-resolution transmission electron microscope (TEM), Fourier-transformed infrared (FT-IR) and Raman spectroscopy. The SEM image indicated the successful formation of the G-D-Ag. The behavior of MTZ on the G-D-Ag as a reliable and robust substrate was investigated by SERS, which indicated mostly a chemical interaction between G-D-Ag and MTZ. The bands of the MTZ normal spectra at 1538, 1463, 1342, 1278, 1156, 1092, 1016, 600, 525 and 410 cm‑1 were enhanced due to the SERS effect. Correlations between the logarithmical scale of MTZ concentrations and SERS signal intensities were established, and a low detection limit of 1.43 × 10‑12 M was successfully obtained. The density functional theory (DFT) approach was utilized to provide reliable assignment of the key Raman bands.

  6. Study of the antifungal potential of novel cellulose/copper composites as absorbent materials for fruit juices.

    Science.gov (United States)

    Llorens, Amparo; Lloret, Elsa; Picouet, Pierre; Fernandez, Avelina

    2012-08-17

    Cellulose/copper composites with antifungal properties have been synthesized by physical/chemical methods. Physical treatments by heat or by a combination of heat and UV radiation provided composites with metallic copper and excellent interfacial adhesion; in contrast, chemical reduction with borohydride generated small although partially aggregated copper oxide nanoparticles. Copper micro/nano-particles and copper ions (Cu(2+)) were released from the cellulose matrix at an adequate rate to achieve a strong antimicrobial activity against Saccharomyces cerevisiae in in vitro experiments. Moreover, the copper oxide composites showed an excellent antifungal activity in pineapple and melon juice, reducing about 4 log cycles the loads of spoilage-related yeasts and moulds. The metallic copper composites reduced in 4 log cycles the load of yeasts and moulds in pineapple juice, although their antifungal activity was weaker in contact with melon juice. Copper loaded absorbent materials could be selectively implemented during the shelf-life of minimally processed fruits to reduce the number of spoilage-related microorganisms in the drip.

  7. Fabrication of CdTe/Si heterojunction solar cell

    Science.gov (United States)

    Bera, Swades Ranjan; Saha, Satyajit

    2016-01-01

    A simple cost effective method is preferred to grow nanoparticles of CdTe. Nanoparticles of CdTe are grown by simple chemical reduction route using EDA as capping agent and Sodium Borohydride as reducing agent. The grown nanoparticles are characterized using transmission electron microscopy (TEM), X-ray diffraction, optical absorption, and photoluminescence study. From optical absorption study, the band-gap was found to be 2.46 eV. From TEM study, the average particle size was found to be within 8-12 nm which confirms the formation of CdTe nanoparticles. Pl spectra indicate the luminescence from surface states at 2.01 eV, which is less compared to the increased band-gap of 2.46 eV. The grown nanoparticles are used to fabricate a heterojunction of CdTe on P-Si by a spin coating technique for solar cell fabrication in a cost effective way. I-V characteristics of the grown heterojunction in dark as well as under light are measured. Efficiency and fill-factor of the device are estimated.

  8. Microwave combustion and sintering without isostatic pressure

    Energy Technology Data Exchange (ETDEWEB)

    Ebadian, M.A.

    1998-01-01

    In recent years interest has grown rapidly in the application of microwave energy to the processing of ceramics, composites, polymers, and other materials. Advances in the understanding of microwave/materials interactions will facilitate the production of new ceramic materials with superior mechanical properties. One application of particular interest is the use of microwave energy for the mobilization of uranium for subsequent redeposition. Phase III (FY98) will focus on the microwave assisted chemical vapor infiltration tests for mobilization and redeposition of radioactive species in the mixed sludge waste. Uranium hexachloride and uranium (IV) borohydride are volatile compounds for which the chemical vapor infiltration procedure might be developed for the separation of uranium. Microwave heating characterized by an inverse temperature profile within a preformed ceramic matrix will be utilized for CVI using a carrier gas. Matrix deposition is expected to commence from the inside of the sample where the highest temperature is present. The preform matrix materials, which include aluminosilicate based ceramics and silicon carbide based ceramics, are all amenable to extreme volume reduction, densification, and vitrification. Important parameters of microwave sintering such as frequency, power requirement, soaking temperature, and holding time will be investigated to optimize process conditions for the volatilization of uranyl species using a reactive carrier gas in a microwave chamber.

  9. Polyacrylonitrile Fibers Anchored Cobalt/Graphene Sheet Nanocomposite: A Low-Cost, High-Performance and Reusable Catalyst for Hydrogen Generation.

    Science.gov (United States)

    Zhang, Fei; Huang, Guoji; Hou, Chengyi; Wang, Hongzhi; Zhang, Qinghong; Li, Yaogang

    2016-06-01

    Cobalt and its composites are known to be active and inexpensive catalysts in sodium borohydride (NaBH4) hydrolysis to generate clean and renewable hydrogen energy. A novel fiber catalyst, cobalt/graphene sheet nanocomposite anchored on polyacrylonitrile fibers (Co/GRs-PANFs), which can be easily recycled and used in any reactor with different shapes, were synthesized by anchoring cobalt/graphene (Co/GRs) on polyacrylonitrile fibers coated with graphene (GRs-PANFs) at low temperature. The unique structure design effectively prevents the inter-sheet restacking of Co/GRs and fully exploits the large surface area of novel hybrid material for generate hydrogen. And the extra electron transfer path supplied by GRs on the surface of GRs-PANFs can also enhance their catalysis performances. The catalytic activity of the catalyst was investigated by the hydrolysis of NaBH4 in aqueous solution with GRs-PANFs. GRs powders and Co powders were used as control groups. It was found that both GRs and fiber contributed to the hydrogen generation rate of Co/GRs-PANFs (3222 mL x min(-1) x g(-1)), which is much higher than that of cobalt powders (915 mL x min(-1) x g(-1)) and Co/GRs (995 mL x min(-1) x g(-1)). The improved hydrogen generation rate, low cost and uncomplicated recycling make the Co/GRs-PANFs promising candidate as catalysts for hydrogen generation. PMID:27427607

  10. Ku80 interaction with apurinic/apyrimidinic sites depends on the structure of DNA ends

    Directory of Open Access Journals (Sweden)

    Kosova A. A.

    2014-01-01

    Full Text Available Aim. The identification of a protein from human cell extract which specifically interacts with the apurinic/apyrimidinic (AP site in the partial DNA duplex containing 5'and 3'-dangling ends (DDE-AP DNA and mimicking clustered DNA damage. Methods. The Schiff base-dependent cross-linking of a protein to AP DNA (borohydride trapping, MALDI-TOF-MS, chromatography, and gel electrophoresis. Results. A human cell extract protein which forms a major covalent adduct with the AP DNA duplex with dangling ends was identified as the Ku80 subunit of Ku antigen by peptide mass mapping based on MALDI-TOF-MS data. The Ku antigen purified from the HeLa cell extract was shown to form the covalent adducts with the same mobility as observed in cell extracts. Conclusions. The Ku80 subunit of Ku antigen can specifically interact with AP DNA forming the Schiff base-mediated adducts which electrophoretic mobility depends on the structure of DNA ends. The difference in electrophoretic mobility can be caused by the cross-linking of AP DNA to distinct target amino acids that appears to reflect unequal positioning of AP DNAs in the complex with Ku antigen.

  11. Thematic outlook: the technical outlook for the fuel cell research network (PACO). September 23, 2003 update no. 16; Veille thematique. La veille technique pour le reseau PACO. Actualisation du 23 septembre 2003, no. 16

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-07-01

    Summaries of several recent articles and patents are gathered here. They deal with fuel cells and hydrogen production and storage. Their different titles are given below: 1)the behaviour of the electrode potential in direct hydrazine fuels 2)a device of desalination fed with a fuel cell 3)experiment in the field of residential fuel cell systems at ECN (Energy Research Center) 4)'design of a divided feeding' for SOFC with an internal reforming system 5)water management and thermal management in a fuel cell vehicle fed with hydrogen extracted from sodium borohydride (NaBH{sub 4}) 6)a mathematical model of propulsion systems by PEMFC for mobile applications 7)assessment of the feasibility of a DMFC containing an alkaline membrane 8)semi-empirical assessment model of the performance of a DMFC, first part: development of the model and validation 9)PEMFC and the challenge of CO 10)materials for SOFC 11)natural gas and LPG desulfurization for fuel cells reformers 12)heat exchangers for reforming techniques 13)desulfurization of a fuel for fuel cell system 14)hydrogen production from solar thermal reactor 15)hydrogen physico-chemical storage: nano-structured storage materials having modified covalent bonds sp2. The references of these articles and patents are detailed. (O.M.)

  12. Natural polymers supported copper nanoparticles for pollutants degradation

    Science.gov (United States)

    Haider, Sajjad; Kamal, Tahseen; Khan, Sher Bahadar; Omer, Muhammad; Haider, Adnan; Khan, Farman Ullah; Asiri, Abdullah M.

    2016-11-01

    In this report, chitosan (CS) was adhered on cellulose microfiber mat (CMM) to prepare CS-CMM. This was used as host for copper (Cu) nanoparticles preparation. After adsorption of Cu2+ ions from an aqueous solution of CuSO4, the metal ions entrapped in CS coating layer was treated with sodium borohydride (NaBH4) to prepare Cu nanoparticles loaded CS-CMM (Cu/CS-CMM). Fourier transform infrared spectroscopy, and X-ray diffraction confirmed the formation of Cu/CS-CMM hybrid. Scanning electron microscopy analysis was performed to reveal the morphology of the prepared catalyst. The prepared Cu/CS-CMM was employed as a catalyst for the degradation of nitro-aromatic compounds of 2-nitrophenol (2NP) and 4-nitrophenol (4NP) as well as an organic cresyl blue (CB) dye. Remarkably, the turnover frequency in the case of 2NP and 4NP using Cu/CS-CMM reaches 103.3 and 88.6 h-1, outperforming previously reported Cu nanoparticles immobilized in hydrogel-based catalytic systems. The rate constants for 2NP, 4NP and CB were 1.2 × 10-3 s-1, 2.1 × 10-3 s-1 and, 1.3 × 10-3 s-1, respectively. Besides, we discussed the separation of the catalyst from the reaction mixture and its re-usability.

  13. Enhanced Methanol Tolerance of Highly Pd rich Pd-Pt Cathode Electrocatalysts in Direct Methanol Fuel Cells

    International Nuclear Information System (INIS)

    Methanol crossover critically restricts the practical application of direct methanol fuel cells (DMFCs). To resolve this crucial difficulty from the standpoint of electrocatalysis, an electrode material having high activity for the oxygen reduction reaction and low activity for the methanol oxidation reaction compared to widely used Pt-based electrodes is needed for DMFC cathodes. In this research carbon-supported Pd-rich Pd–Pt bimetallic nanoparticle electrocatalysts with 60 wt.% metal content were prepared for this purpose by sodium borohydride reduction of metal chlorides. The physical features of the prepared nanoparticles were investigated by transmission electron microscopy, energy dispersive X-ray spectroscopy, atomic absorption spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and X-ray absorption near edge spectroscopy. Methanol tolerance was tested by means of rotating disk electrode (RDE) voltammetry using oxygen-saturated methanol-containing electrolyte solutions as the anode fuel for DMFC unit cell performance tests. In the RDE measurements, Pd-rich electrocatalysts (carbon-supported Pd19Pt1 nanoparticles) showed excellent methanol tolerance compared with Pd-free Pt electrocatalyst. When Pd19Pt1 nanoparticles were used as a DMFC cathode catalyst, unit cell performance tests showed that the i-V curves of the Pd19Pt1 electrocatalyst decreased slightly with increasing methanol concentration, while that of the Pt electrocatalyst decreased rapidly. The results in a liquid-feed DMFC unit cell test were in good agreement with the methanol tolerant characteristics identified in the RDE measurements

  14. Performance evaluation of direct borohydride–hydrogen peroxide fuel cells with electrocatalysts supported on multiwalled carbon nanotubes

    International Nuclear Information System (INIS)

    The performance of direct borohydride–hydrogen peroxide fuel cells with electrocatalysts supported on multiwalled carbon nanotubes is evaluated under various conditions. Electrocatalysts are reduced on multiwalled carbon nanotubes by NaH2PO2 and electrodes are investigated using scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and fuel cell testing. The maximum power density decreases with increasing NaBH4 concentration, likely owing to increases in NaBH4 decomposition and crossover rates and to production of increasing amounts of NaBO2. In contrast, the maximum power density increases with increasing H2O2 concentration, likely owing to increases in reactant concentrations. Moreover, increased operating temperatures improve decomposition and electrochemical reaction rates. A thin membrane increases fuel crossover, whereas a thick membrane decreases the maximum power density; consequently, the Nafion 212 membrane is the optimal thickness for use in fuel cells such as those studied here. Under selected conditions, the maximum power density is 101.9 mW/cm2. As operation time increases, fuel cell performance is degraded by oxidation and Na deposition. - Highlights: • Maximum power density decreases as NaBH4 (sodium borohydride) concentration increases. • Maximum power density increases as H2O2 (hydrogen peroxide) concentration increases. • High operating temperatures cause fast electrochemical and decomposition reactions. • Nafion 212 is the most suitable membrane owing to its thickness. • Fuel cell performance decreases owing to oxidation and Na deposition

  15. Effect of cationic plastoquinone SkQ1 on electron transfer reactions in chloroplasts and mitochondria from pea seedlings.

    Science.gov (United States)

    Samuilov, V D; Kiselevsky, D B

    2015-04-01

    Plastoquinone bound with decyltriphenylphosphonium cation (SkQ1) penetrating through the membrane in nanomolar concentrations inhibited H2O2 generation in cells of epidermis of pea seedling leaves that was detected by the fluorescence of 2',7'-dichlorofluorescein. Photosynthetic electron transfer in chloroplasts isolated from pea leaves is suppressed by SkQ1 at micromolar concentrations: the electron transfer in chloroplasts under the action of photosystem II or I (with silicomolybdate or methyl viologen as electron acceptors, respectively) is more sensitive to SkQ1 than under the action of photosystem II + I (with ferricyanide or p-benzoquinone as electron acceptors). SkQ1 reduced by borohydride is oxidized by ferricyanide, p-benzoquinone, and, to a lesser extent, by silicomolybdate, but not by methyl viologen. SkQ1 is not effective as an electron acceptor supporting O2 evolution from water in illuminated chloroplasts. The data on suppression of photosynthetic O2 evolution or consumption show that SkQ1, similarly to phenazine methosulfate, causes conversion of the chloroplast redox-chain from non-cyclic electron transfer mode to the cyclic mode without O2 evolution. Oxidation of NADH or succinate in mitochondria isolated from pea roots is stimulated by SkQ1.

  16. Polyelectrolyte induced formation of silver nanoparticles in copolymer hydrogel and their application as catalyst

    Energy Technology Data Exchange (ETDEWEB)

    He, Yongqiang [Department of Applied Chemistry, Yuncheng University, Yuncheng 044000 (China); Huang, Guanbo, E-mail: gbhuang2007@hotmail.com [Department of Chemistry, School of Science, Tianjin University, Tianjin 300072 (China); Pan, Zeng; Liu, Yue [Department of Chemistry, School of Science, Tianjin University, Tianjin 300072 (China); Gong, Qiaojuan; Yao, Chenzhong [Department of Applied Chemistry, Yuncheng University, Yuncheng 044000 (China); Gao, Jianping, E-mail: jianpingg@eyou.com [Department of Chemistry, School of Science, Tianjin University, Tianjin 300072 (China)

    2015-10-15

    Highlights: • A simple route for the in situ preparation of Ag nanoparticles has been developed. • The Ag loaded hydrogel showed catalytic activity for reduction of 4-nitrophenol. • The catalyst can be recovered by simple separation and showed good recyclability. - Abstract: A simple route for the in situ preparation of catalytically active Ag nanoparticles (NPs) in hydrogel networks has been developed. The electronegativity of the amide and carboxyl groups on the poly(acrylamide-co-acryl acid) chains caused strong binding of the Ag{sup +} ions which made the ions distribute uniformly inside the hydrogels. When the Ag{sup +} loaded hydrogels were immersed in NaBH{sub 4} solution, the Ag{sup +} ions on the polymer networks were reduced to Ag NPs. The resultant hydrogel showed good catalytic activity for the reduction of a common organic pollutant, 4-nitrophenol, with sodium borohydride. A kinetic study of the catalytic reaction was carried out and a possible reason for the decline of the catalytic performance with reuse is proposed.

  17. Atomic absorption determination, in metal sulphide concentrates, of the elements that form gaseous hydrides

    International Nuclear Information System (INIS)

    An account is given of the investigational work on the determination of trace amounts of arsenic, antimony, bismuth, germanium, selenium, and tellurium by the technique using hydride generation and atomic-absorption spectrophotometry. The gaseous hydride is generated by reduction with sodium borohydride, and is subsequently swept by a flow of nitrogen into an air-entrained hydrogen-nitrogen flame. The generation equipment used is simple and inexpensive, and can be readily assembled in most laboratories. The optimum parameters were determined for each element. The effects of 31 probable interfering elements were investigated, and it was found that, although the majority did not interfere, severe interference was encountered when copper, nickel, and the noble metals were present. Methods for the elimination of copper and nickel were developed to allow the determination of arsenic, antimony, bismuth, selenium, and tellurium at the lower parts-per-million level in metal sulphide concentrates with an acceptable accuracy and precision. The determination of microgram amounts of germanium was found to be unsatisfactory

  18. Assembly fabrication of linkers on glass surface and their effect on DNA synthesis and hybridization

    Institute of Scientific and Technical Information of China (English)

    ShenJiayao; XiaoPengfeng; HouPeng; JiMeiju; SunXiao; HeNongyue

    2003-01-01

    Linkers were assembled on a glass surface based on the hydrolysis and condensation of 3-glycidoxy-propyltrimethoxysilane (GPS). After the assembly of GPS, four approaches were tried to open the ending epoxide group of GPS or to further elongate the linkers. The effect of these approaches on DNA in situ synthesis and hybridization was investigated. For the spacing of the synthesis initiation sites, the wettability of the support and the length of the linking group that attaches the initiation site to the surface have direct influences on the yield of coupling reactions and the subsequent hybridization events. X-ray photoelectron spectroscopy (XPS) and mean contact angles of deionized water of the above slides were measured to assess the linker's characteristics in each procedure. It was proved that the glass slides were successfully modified and became excellent supports for the oligonucleotides synthesis. In addition, it proved best for the in situ oligonueleotides synthesis that a glass slide was in turn treated with ethylenediamine, glutaradehyde, ethanolamine and sodium borohydride solution at ambient temperature after silanized with GPS.

  19. A solid control strategy for preparation of silver nanoparticles in aqueous medium

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Daechul [Soonchunhyang University, Asan (Korea, Republic of); Kwon, Sung-Hyun [Gyeongsang National University, Tongyong (Korea, Republic of)

    2015-12-15

    Uniformly distributed, spherically shaped, mild concentrated silver nanoparticles with single-digit to hundreds nm size have been prepared by reducing silver nitrate with popular reducers like sodium borohydride or hydrazine in the presence of ordinary stabilizers such as SDS, PVP, Polysorbates and ultrasonication. Uv-visble spectroscopic analysis, particle size analysis, and particle-imaging through transmission electron microscopy (TEM) were used for nanoparticle characterization. Higher temperature accelerated the reduction rates, which follows the typical autocatalytic kinetics. Particularly, ultrasonication helped to facilitate the crucial stage of reduction phase to result in excellent quality of nanosolution, such as narrow distribution of particles and size uniformity. We found that initial location or arrangement of silver ions in clouds of stabilizers and 'effectve mixing' in the stage of reduction were vital for successful preparation of silver nanosolution. Also, reagent/stabilizer ratio, reducer input, solution environment such as pH, temperature, and stabilizer properties were optimized and discussed in detail. Proper selection of stabilizer and molar ratio to reagent and effective 'mixing' for preventing grain growth needs to be investigated more in the future work.

  20. Recovery of high purity precious metals from printed circuit boards

    International Nuclear Information System (INIS)

    Waste printed circuit boards (WPCB) have an inherent value because of the precious metal content. For an effective recycling of WPCB, it is essential to recover the precious metals. This paper reports a promising method to recover the precious metals. Aqua regia was used as a leachant and the ratio between metals and leachant was fixed at 1/20 (g/ml). Silver is relatively stable so the amount of about 98 wt.% of the input was recovered without an additional treatment. Palladium formed a red precipitate during dissolution, which were consisted of Pd(NH4)2Cl6. The amount precipitated was 93 wt.% of the input palladium. A liquid-liquid extraction with toluene was used to extract gold selectively. Also, dodecanethiol and sodium borohydride solution were added to make gold nanoparticles. Gold of about 97 wt.% of the input was recovered as nanoparticles which was identified with a high-resolution transmission electron microscopy through selected area electron diffraction and nearest-neighbor lattice spacing.

  1. A comprehensive study on the effect of Ru addition to Pt electrodes for direct ethanol fuel cell

    Indian Academy of Sciences (India)

    J Datta; S Singh; S Das; N R Bandyopadhyay

    2009-12-01

    The electro-oxidation of ethanol was studied over nanosized Pt and different compositions of PtRu catalysts synthesized by the borohydride reduction method. Physicochemical characterizations of the catalyst material were made by X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with EDX analysis and transmission electron microscopy (TEM). XRD patterns showed that Ru induces a contraction of the Pt lattice. EDX provided the composition of binary catalysts while TEM images indicated uniform distribution of discrete nanoparticle of the catalysts with narrow range. The electro-catalytic activities of the materials towards ethanol oxidation were investigated through electrochemical techniques, viz. cyclic voltammetry (CV), potentiodynamic polarization, chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) at room temperature. The onset potential of ethanol electro-oxidation is lowered on bimetallic PtRu catalysts compared to that on Pt alone. Of the investigated catalyst compositions the one with the highest electrocatalytic activity was found to be Pt82Ru18. This enhancement towards ethanol oxidation is explained on the basis of a structural effect and modified bi-functional mechanism.

  2. Silver nanoparticles of variable morphology synthesized in aqueous foams as novel templates

    Indian Academy of Sciences (India)

    Saikat Mandal; Sujatha K Arumugam; Renu Pasricha; Murali Sastry

    2005-08-01

    In this paper, we describe the synthesis of silver nanocrystals within aqueous foams as a template. More specifically, we show that aqueous Ag+ ions may be electrostatically complexed with the anionic surfactants aerosol OT (sodium bis-2-ethylhexyl-sulfosuccinate, (AOT) and sodium dodecyl sulphate (SDS)) in a highly stable liquid foam. After drainage of the foam, the silver ions are reduced in situ by introducing sodium borohydride into the foam by capillary flow. This leads to the formation of silver nanoparticles of spherical, tape- and sheet-like morphology in the foam. The structure of the foam is extremely complex and presents reaction sites of different spatial extent. The differences in foam reaction–site geometry are believed to be responsible for the morphology variation in the silver nanoparticles observed. The silver nanoparticles are observed to be extremely stable in solution suggesting that the AOT or SDS molecules stabilize them. This approach appears promising for application in large-scale synthesis of nanoparticles and may be readily extended to other chemical compositions.

  3. Production of Platinum Atom Nanoclusters at One End of Helical Plant Viruses

    Directory of Open Access Journals (Sweden)

    Yuri Drygin

    2013-01-01

    Full Text Available Platinum atom clusters (Pt nanoparticles, Pt-NPs were produced selectively at one end of helical plant viruses, tobacco mosaic virus (TMV and potato virus X (PVX, when platinum coordinate compounds were reduced chemically by borohydrides. Size of the platinum NPs depends on conditions of the electroless deposition of platinum atoms on the virus. Results suggest that the Pt-NPs are bound concurrently to the terminal protein subunits and the 5′ end of encapsidated TMV RNA. Thus, a special structure of tobacco mosaic virus and potato X virus particles with nanoparticles of platinum, which looks like a push-pin with platinum head and virus needle, was obtained. Similar results were obtained with ultrasonically fragmented TMV particles. By contrast, the Pt-NPs fully filled the central axial hole of in vitro assembled RNA-free TMV-like particles. We believe that the results presented here will be valuable in the fundamental understanding of interaction of viral platforms with ionic metals and in a mechanism of nanoparticles formation.

  4. Microwave combustion and sintering without isostatic pressure

    International Nuclear Information System (INIS)

    In recent years interest has grown rapidly in the application of microwave energy to the processing of ceramics, composites, polymers, and other materials. Advances in the understanding of microwave/materials interactions will facilitate the production of new ceramic materials with superior mechanical properties. One application of particular interest is the use of microwave energy for the mobilization of uranium for subsequent redeposition. Phase III (FY98) will focus on the microwave assisted chemical vapor infiltration tests for mobilization and redeposition of radioactive species in the mixed sludge waste. Uranium hexachloride and uranium (IV) borohydride are volatile compounds for which the chemical vapor infiltration procedure might be developed for the separation of uranium. Microwave heating characterized by an inverse temperature profile within a preformed ceramic matrix will be utilized for CVI using a carrier gas. Matrix deposition is expected to commence from the inside of the sample where the highest temperature is present. The preform matrix materials, which include aluminosilicate based ceramics and silicon carbide based ceramics, are all amenable to extreme volume reduction, densification, and vitrification. Important parameters of microwave sintering such as frequency, power requirement, soaking temperature, and holding time will be investigated to optimize process conditions for the volatilization of uranyl species using a reactive carrier gas in a microwave chamber

  5. Oxygen reduction reaction catalyzed by platinum nanonetwork prepared by template free one step synthesis for polymer electrolyte membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Narayanamoorthy, B. [Department of Chemistry, Faculty of Science, Sri Chandrasekharendra Saraswathi Viswa Mahavidyalaya (SCSVMV University), Enathur, Kanchipuram 631 561 (India); Kumar, B.V.V.S. Pavan; Eswaramoorthy, M. [Nanomaterials and Catalysis Lab, Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore 560 064 (India); Balaji, S., E-mail: prof.balaji13@gmail.com [Department of Chemistry, Faculty of Science, Sri Chandrasekharendra Saraswathi Viswa Mahavidyalaya (SCSVMV University), Enathur, Kanchipuram 631 561 (India)

    2014-07-01

    Highlights: • Supportless Pt nanonetwork (Pt NN) synthesized by novel template free one step method as per our earlier reported procedure. • Electrocatalytic activity of Pt NN studied taking oxygen reduction reaction in acid medium. • Kinetic and thermodynamic parameters were deduced under hydrodynamic conditions. • ORR mechanistic pathway was proposed based on kinetic rate constants. • ADT analysis found enhanced stability (5000 cycles) for Pt NN than Pt NN/VC and reported Pt/C. - Abstract: The reduction reaction of molecular oxygen (ORR) was investigated using supportless Pt nanonetwork (Pt NN) electrocatalyst in sulfuric acid medium. Pt NN was prepared by template free borohydride reduction. The transmission electron microscope images revealed a network like nano-architecture having an average cluster size of 30 nm. The electrochemical characterization of supportless and Vulcan carbon supported Pt NN (Pt NN/VC) was carried out using rotating disc and ring disc electrodes at various temperatures. Kinetic and thermodynamic parameters were estimated under hydrodynamic conditions and compared with Pt NN/VC and reported Pt/C catalysts. The accelerated durability test revealed that supportless Pt NN is quite stable for 5000 potential cycles with 22% reduction in electrochemical surface area (ECSA). While the initial limiting current density has in fact increased by 11.6%, whereas Pt NN/VC suffered nearly 55% loss in ECSA and 13% loss in limiting current density confirming an enhanced stability of supportless Pt NN morphology for ORR compared to conventional Pt/C ORR catalysts in acid medium.

  6. Development of novel protein-Ag nanocomposite for drug delivery and inactivation of bacterial applications.

    Science.gov (United States)

    Vimala, Kanikireddy; Varaprasad, Kokkarachedu; Sadiku, Rotimi; Ramam, Koduri; Kanny, Krishnan

    2014-02-01

    The potential applications, in the biomedical fields, of curcumin loaded silver nanocomposite were studied by using bovine serum albumin (protein) and acrylamide. The design and development of silver nanoparticles with small size and adequate stability are very important, in addition to their applicability, particularly in bio-medicine. In this study, silver nanoparticles were prepared by chemical reduction method, employing sodium borohydride as the reducing agent for silver nanoparticles. The properties of the protein hydrogels formed were characterized via Fourier transform infrared spectroscopy and X-ray diffraction analyses. The size and its distribution, and formation of metal nanoparticles were confirmed by transmission electron microscopy indicating the diameter of the silver nanoparticles in the range of 3-8 nm. The thermal study of curcumin-silver nanocomposite hydrogels was determined by thermo-gravimetric analysis. In order to increase the antibacterial activity of theses inorganic nanomaterials, natural biological curcumin was incorporated into the protein hydrogel. The main emphasis in this investigation is to increase the antibacterial activity of the hydrogels by loading curcumin, for advanced medical application and as a model drug.

  7. Quantification of glycated N-terminal peptide of hemoglobin using derivatization for multiple functional groups of amino acids followed by liquid chromatography/tandem mass spectrometry.

    Science.gov (United States)

    Sakaguchi, Yohei; Kinumi, Tomoya; Yamazaki, Taichi; Takatsu, Akiko

    2016-02-01

    A novel method of amino acid analysis using derivatization of multiple functional groups (amino, carboxyl, and phenolic hydroxyl groups) was applied to measure glycated amino acids in order to quantify glycated peptides and evaluate the degree of glycation of peptide. Amino and carboxyl groups of amino acids were derivatized with 1-bromobutane so that the hydrophobicities and basicities of the amino acids, including glycated amino acids, were improved. These derivatized amino acids could be detected with high sensitivity using LC-MS/MS. In this study, 1-deoxyfructosyl-VHLTPE and VHLTPE, which are N-terminal peptides of the β-chains of hemoglobin, were selected as target compounds. After reducing the peptide sample solution with sodium borohydride, the obtained peptides were hydrolyzed with hydrochloric acid. The released amino acids were then derivatized with 1-bromobutane and analyzed with LC-MS/MS. The derivatized amino acids, including glycated amino acids, could be separated using an octadecyl silylated silica column and good sharp peaks were detected. We show a confirmatory experiment that the proposed method can be applied to evaluate the degree of glycation of peptides, using mixtures of glycated and non-glycated peptide.

  8. Shape tailored green synthesis and catalytic properties of gold nanocrystals

    Science.gov (United States)

    Rajan, Anish; MeenaKumari, M.; Philip, Daizy

    2014-01-01

    The use of environmentally benign procedures is highly desirable for the synthesis of nanoparticles. Here we report a simple, versatile, economic, ecofriendly and reproducible green method for the size-tunable synthesis of stable and crystalline gold nanoparticles of varied shape using aqueous extract of Garcinia Combogia fruit. The predominant anisotropic nature in the morphology of synthesized particles at lower quantities of extract gradually shifted to spherical particles with larger quantity of extract and increase of temperature. The onset of reduction, the time-evolution of the Surface Plasmon Resonance (SPR) and the catalytic activity are studied using UV-Visible spectroscopy. The Selected Area Diffraction (SAED) pattern, the lattice fringes in the High Resolution Transmission Electron Microscopic (HRTEM) image and the X-ray Diffraction (XRD) pattern clearly show the pure crystalline nature of the synthesized gold nanoparticles. The role of carboxyl group present in Garcinia Combogia fruit extract in the reduction of chloroaurate ions is established using Fourier Transform Infrared (FTIR) spectra. The size dependent catalytic activity of the green synthesized gold nanoparticles on the reduction of 4-Nitrophenol to 4-Aminophenol using sodium borohydride is studied and reported for the first time. The first order kinetics is fitted and rate constants are calculated. Catalytically active green synthesized gold nanoparticles with controllable size and shape presents an advanced step in future biomedical and chemical applications.

  9. Chitosan based polymer matrix with silver nanoparticles decorated multiwalled carbon nanotubes for catalytic reduction of 4-nitrophenol.

    Science.gov (United States)

    Alshehri, Saad M; Almuqati, Turki; Almuqati, Naif; Al-Farraj, Eida; Alhokbany, Norah; Ahamad, Tansir

    2016-10-20

    A novel catalyst for the reduction of 4-nitrophenol (4-NP) was prepared using carboxyl group-functionalized multiwalled carbon nanotubes (MWCNTs), polymer matrix, and silver nanoparticles (AgNPs). The AgNPs were prepared by the reduction of silver nitrate by trisodium citrate in the MWCNTs-polymer nanocomposite; the size of the synthesized AgNPs was found to be 3nm (average diameter). The synthesized nanocomposites were characterized using several analytical techniques. Ag@MWCNTs-polymer composite in the presence of sodium borohydride (NaBH4) in aqueous solution is an effective catalyst for the reduction of 4-NP. The apparent kinetics of reduction has a pseudo-first-order kinetics, and the rate constant and catalytic activity parameter were found to be respectively 7.88×10(-3)s(-1)and 11.64s(-1)g(-1). The MWCNTs-polymer nanocomposite renders stability to AgNPs against the environment and the reaction medium, which means that the Ag@MWCNTs-polymer composite can be re-used for many catalytic cycles. PMID:27474552

  10. Fast and facile preparation of CTAB based gels and their applications in Au and Ag nanoparticles synthesis

    International Nuclear Information System (INIS)

    We have demonstrated that the gel-like mesophase of Cetyltrimethylammonium bromide (CTAB) can be synthesized by judicial adjustment of water to surfactant molar ratio (W0), without using any additional salts, gelating agents or co-surfactants. Gel formation was found to be highly dependent on the water to surfactant molar ratio (W0), with the lowest value of W0 (41.5) resulting in rapid gel formation. Environmental scanning electron microscope (ESEM) analysis revealed that the gel was comprised of interconnected cylindrical structures. The presence of hydrogen bonding in the gel-like mesophase was confirmed by Fourier Transform Infrared spectroscopy (FTIR) analysis. Rheology measurements revealed that all the gel samples were highly viscoelastic in nature. Furthermore, Au and Ag containing CTAB gels were explored as precursors for the preparation of spherical Gold (Au) and Silver (Ag) nanoparticles using Sodium borohydride (NaBH4) as reducing agent. The effects of NaBH4 concentration on the particle size and morphology of the Au and Ag nanoparticles have also been studied. - Highlights: • A facile synthesis of CTAB based gel-like mesophase is reported. • CTAB gels were obtained by adjusting water to surfactant molar ratio (W0). • FTIR analysis revealed that hydrogen bonding plays a key role in gel formation. • Au, Ag nanoparticles were synthesized by using CTAB gel and NaBH4

  11. Preparation of spherical and cubic Fe55Co45 microstructures for studying the role of particle morphology in magnetorheological suspensions

    Science.gov (United States)

    Arief, Injamamul; Mukhopadhyay, P. K.

    2014-06-01

    Cubic and spherical Fe55Co45 alloyed microstructures were synthesized by borohydride reduction from aqueous solutions of metallic precursors, using stabilizers and polymer. Monosodium citrate, sodium acetate and PEG 6000 were utilized as electrostatic stabilizers and polymeric surface modifier. Suitable reaction conditions were maintained for synthesis of predominantly larger particles (0.7 µm to 1.2 µm), that facilitates use in magnetorheological fluids. Surface morphological studies by scanning electron microscopy revealed well shaped cubic and spherical geometry for the citrate and polymer-stabilized Fe55Co45 alloys, while the alloy compositions remained nearly the same for both. X-ray diffractions of the as-prepared and annealed samples under various temperatures showed high degree of crystallinity with increasing temperatures. Studies of D.C. magnetization of the systems reveal that the particles have a core-shell structure, with inner magnetic core having a diameter around 30 nm with a log-normal distribution. Magnetorheological studies were performed with 8 vol% suspensions of as-synthesized particles dispersed in silicone oil (viscosity 30 mPa s at 25 °C) under different magnetic fields. Detailed studies of the magnetorheological properties were studied on these systems for practical use.

  12. Facile solvothermal synthesis of highly active and robust Pd1.87Cu0.11Sn electrocatalyst towards direct ethanol fuel cell applications

    Science.gov (United States)

    Jana, Rajkumar; Dhiman, Shikha; Peter, Sebastian C.

    2016-08-01

    Ordered intermetallic Pd1.87Cu0.11Sn ternary electrocatalyst has been synthesized by sodium borohydride reduction of precursor salts Pd(acac)2, CuCl2.2H2O and SnCl2 using one-pot solvothermal synthesis method at 220 °C with a reaction time of 24 h. To the best of our knowledge, here for the first time we report surfactant free synthesis of a novel ordered intermetallic ternary Pd1.87Cu0.11Sn nanoparticles. The ordered structure of the catalyst has been confirmed by powder x-ray diffraction, transmission electron microscopy (TEM). Composition and morphology of the nanoparticles have been confirmed through field emission scanning electron microscopy, energy-dispersive spectrometry and TEM. The electrocatalytic activity and stability of the ternary electrocatalyst towards ethanol oxidation in alkaline medium was investigated by cyclic voltammetry and chronoamperometry techniques. The catalyst is proved to be highly efficient and stable upto 500th cycle and even better than commercially available Pd/C (20 wt%) electrocatalysts. The specific and mass activity of the as synthesized ternary catalyst are found to be ∼4.76 and ∼2.9 times better than that of commercial Pd/C. The enhanced activity and stability of the ordered ternary Pd1.87Cu0.11Sn catalyst can make it as a promising candidate for the alkaline direct ethanol fuel cell application.

  13. Synthesis of self-assembly plasmonic silver nanoparticles with tunable luminescence color

    Energy Technology Data Exchange (ETDEWEB)

    Al-Ghamdi, Haifa S.; Mahmoud, Waleed E., E-mail: w_e_mahmoud@yahoo.com

    2014-01-15

    Assembly is an elegant and effective bottom-up approach to prepare arrays of nanoparticles from nobel metals. Noble metal nanoparticles are perfect building blocks because they can be prepared with an adequate functionalization to allow their assembly and with controlled sizes. Herein, we report a novel recipe for the synthesis of self-assembled silver nanoparticles with tunable optical properties and sizes. The synthetic route followed here based on the covalent binding among silver nanoparticles by means of poly vinyl alcohol for the first time. The size of silver nanoparticle is governed by varying the amount of sodium borohydride. The as-synthesized nanoparticles were characterized by transmission electron microscopy, x-ray diffraction, energy dispersive x-ray spectroscopy, selected area electron diffraction and UV–vis spectroscopy. Results depicted that self-assembly of mono-dispersed silver nanoparticles with different sizes have been achieved. The silver nanostructure has a single crystalline faced centered cubic structure with growth orientation along (1 1 1) facet. These nanoparticles exhibited localized surface plasmon resonance at 403 nm. The luminescence peaks were red-sifted from violet to green due to the increase of the particle sizes. -- Highlights: • Self-assembled silver nanoparticles based PVA were synthesized. • NaBH{sub 4} amount was found particle size dependent. • Silver nanoparticles strongly affected the surface plasmon resonance. • Highly symmetric luminescence emission band narrow width is obtained. • Dark field image showed a tunable color change from violet to green.

  14. Dynamic Light Scattering Study of Reverse Micellar Systems for the Synthesis of Iron-Based Nanofluids

    Science.gov (United States)

    Graeve, Olivia A.; Sinha, Kaustav

    Iron nanoparticles dispersed in hydraulic oil were prepared by mixing two microemulsions containing iron (II) sulfate and sodium borohydride at a temperature of 60°C. Six values of ω0 = [water]/[surfactant] were used, namely 5, 10, 15, 20, 25, and 30. Dynamic light scattering measurements of the hydrodynamic radius of the reverse micelles showed that the average size, surfactant shell thickness and water core radius, increased with ω0. The micelle size distribution for ω0 values of 5, 10, and 15, was in the nanometer regime, while for ω0 values of 20, 25, and 30 it was in the micrometer regime. Scanning electron microscopy showed that the nanoparticle diameters were around 30 nm for the powders prepared using an ω0 = 10. In addition, a comparison between the particle size distribution of the iron nanoparticles dispersed in isopropyl alcohol and the iron nanoparticles in the reverse micellar solution was made. It was shown that once the particles are cleaned and separated from the micellar solution, they agglomerate into particles that are about 1 μm in size.

  15. Graphene Dendrimer-stabilized silver nanoparticles for detection of methimazole using Surface-enhanced Raman scattering with computational assignment

    Science.gov (United States)

    Saleh, Tawfik A.; Al-Shalalfeh, Mutasem M.; Al-Saadi, Abdulaziz A.

    2016-08-01

    Graphene functionalized with polyamidoamine dendrimer, decorated with silver nanoparticles (G-D-Ag), was synthesized and evaluated as a substrate with surface-enhanced Raman scattering (SERS) for methimazole (MTZ) detection. Sodium borohydride was used as a reducing agent to cultivate silver nanoparticles on the dendrimer. The obtained G-D-Ag was characterized by using UV-vis spectroscopy, scanning electron microscope (SEM), high-resolution transmission electron microscope (TEM), Fourier-transformed infrared (FT-IR) and Raman spectroscopy. The SEM image indicated the successful formation of the G-D-Ag. The behavior of MTZ on the G-D-Ag as a reliable and robust substrate was investigated by SERS, which indicated mostly a chemical interaction between G-D-Ag and MTZ. The bands of the MTZ normal spectra at 1538, 1463, 1342, 1278, 1156, 1092, 1016, 600, 525 and 410 cm-1 were enhanced due to the SERS effect. Correlations between the logarithmical scale of MTZ concentrations and SERS signal intensities were established, and a low detection limit of 1.43 × 10-12 M was successfully obtained. The density functional theory (DFT) approach was utilized to provide reliable assignment of the key Raman bands.

  16. Synthesis of gold nanorods with a longitudinal surface plasmon resonance peak of around 1250 nm

    Science.gov (United States)

    Nguyen, Thi Nhat Hang; Le Trinh Nguyen, Thi; Thanh Tuyen Luong, Thi; Thang Nguyen, Canh Minh; Nguyen, Thi Phuong Phong

    2016-03-01

    We prepared gold nanorods and joined them to chemicals such as tetrachloauric (III) acid trihydrate, silver nitrate, hydroquinone, hexadecyltrimethylammonium bromide, sodium hydroxide and sodium borohydride using the seed-mediated method. The combination of hydroquinone, with or without salicylic acid, influences the size of the gold nanorods, and this is demonstrated by the results of TEM images, UV-vis spectra and the value of the longitudinal surface plasmon resonance peak with respect to the UV-vis spectra. By changing the Ag+ ion and hydroquinone concentration and the combination of hydroquinone and salicylic acid, the size of the gold nanorods can be controlled and this is manifested by longitudinal surface plasmon resonance peaks forming between 875 and 1278 nm. In particular, sample E2 achieved a longitudinal surface plasmon peak at 1273 nm and an aspect ratio of more than 10 by modifying the hydroquinone to 2.5 mM and salicylic acid to 0.5 mM concentration in the growth solution.

  17. CHEMICAL MODIFICATION OF LIGNIN IN POPLAR APMP PULPS TO PREVENT LIGHT INDUCED YELLOWING%木质素化学改性抑制杨木碱性过氧化氢机械浆返色的研究

    Institute of Scientific and Technical Information of China (English)

    房桂干; Alain,C

    2000-01-01

    中试系统制备了杨木碱性过氧化氢机械浆.分别在水相/有机溶剂相/气相等条件下,使用乙酐处理杨木化机浆(原浆及硼氢化钠还原后纸浆),分别抄造成60g/m 2纸片,测定了不同时间紫外线照射后试样白度.运用返色值(PC no.)和白度稳定效果(BSE) 等指标评价处理后浆料的光学稳定性.研究结果表明,有机溶剂相和气相乙酰化后的纸浆 ,光学稳定性的提高程度取决于乙酐用量和反应时间即乙酰化程度.通过乙酰化,可以获取光学完全稳定的杨木化机浆.紫外漫射反射光谱表明,杨木APMP机械浆光诱导返色的主要原因是纸浆木质素中羰基和酚羟基团吸收紫外光后变化形成发色结构所致.还原配合纸浆乙酰化处理, 可能成为防止高得率纸浆返色的工业应用方法.%Different brightness level s of poplar APMP pulps were prepared in a pilot scale system by alkaline peroxide mechanical pulping process, Un-treated and reduced pulps(borohydride reduction)were modified by acetic anhydride under different conditions, such as in aqueous, organic solvents and gaseous phases.The brightness of pulps before and after UV-light exposure for different periods were measured on handsheets, post-colour number and BSE (brightness stabilizing effect)were used to evaluate the photo -stability of the treated pulps. The results show that, both gaseous and organic phase acetylations improve pulps brightness stability more or less depending on am ount of acetic anhydride applied and reaction time I. E. Degree of acetylation. Co mpletely stabilized pulps were obtained by thorough acetylation.Form UV diffuse reflectance spectra, it seems that carbonyl and phenolic groups mainly contribute to the light-induced yellowing of poplar APMP. Sodium borohydride/so dium bisulfite mixture treatment of pulps followed by gaseous phase acetylation on paper sheet was proposed to be one of the practical process for yellowing inhibition of

  18. The induction phenomenon and catalytic deactivation of thiolate-stabilized raspberry-like polymer composites coated with gold nanoparticles

    Science.gov (United States)

    Li, Maolin; Chen, Guofang; Bhuyain, Shiper

    2015-01-01

    Alkylthiolate ligands play dual roles in metal nanoparticles-coated polymer composite catalysts: stabilizer and deactivator. Herein, individual raspberry-like polymer composite spheres coated with gold nanoparticles were separated from each other in the presence of 6-mercaptohexanoic acid or 3-mercaptopropionic acid ligands. Effects of thiolate ligands on the induction time and the catalytic activity of such non-aggregated polymer composites were investigated experimentally and theoretically in the 4-nitrophenol/NaBH4 model reaction from the following aspects: ligand surface coverage, chain order and chain length. With the increase in alkylthiolate surface coverage and chain order on composite particles, the induction time increases first and then decreases, which can be explained based on spontaneous dynamic surface restructuring and electron injection from borohydride ions to the gold nanoparticle surface. The catalytic activity is compromised with the existence of thiolate ligands, but is enhanced with increasing alkylthiolate ligand coverage, which can be ascribed to sulfur-induced electronic charge depletion of the gold nanoparticles. The increment of CH2 in alkylthiolate chains results in the increase of induction time and the decrease of the catalytic activity, which can be attributed to the steric hindrance effect. The reactant addition sequence was also found to affect the induction time and the catalytic activity, which can be partially credited to NaBH4 reductant-induced desorption of thiolate ligands.Alkylthiolate ligands play dual roles in metal nanoparticles-coated polymer composite catalysts: stabilizer and deactivator. Herein, individual raspberry-like polymer composite spheres coated with gold nanoparticles were separated from each other in the presence of 6-mercaptohexanoic acid or 3-mercaptopropionic acid ligands. Effects of thiolate ligands on the induction time and the catalytic activity of such non-aggregated polymer composites were

  19. Brevenal, a brevetoxin antagonist from Karenia brevis, binds to a previously unreported site on mammalian sodium channels.

    Science.gov (United States)

    Gold, Elena P; Jacocks, Henry M; Bourdelais, Andrea J; Baden, Daniel G

    2013-06-01

    Brevetoxins are a family of ladder-frame polyether toxins produced by the marine dinoflagellate Karenia brevis. During blooms of K. brevis, inhalation of brevetoxins aerosolized by wind and wave action can lead to asthma-like symptoms in persons at the beach. Consumption of either shellfish or finfish contaminated by K. brevis blooms can lead to the development of neurotoxic shellfish poisoning. The toxic effects of brevetoxins are due to binding at a defined site on, and subsequent activation of, voltage-sensitive sodium channels (VSSCs) in cell membranes (site 5). In addition to brevetoxins, K. brevis produces several other ladder-frame compounds. One of these compounds, brevenal, has been shown to antagonize the effects of brevetoxin. In an effort to further characterize to effects of brevenal, a radioactive analog ([(3)H]-brevenol) was produced by reducing the side-chain terminal aldehyde moiety of brevenal to an alcohol using tritiated sodium borohydride. A KD of 67 nM and Bmax of 7.1 pmol/mg protein were obtained for [(3)H]-brevenol in rat brain synaptosomes, suggesting a 1:1 matching with VSSCs. Brevenal and brevenol competed for [(3)H]-brevenol binding with Ki values of 75 nM and 56 nM, respectively. However, although both brevenal and brevenol can inhibit brevetoxin binding, brevetoxin was completely ineffective at competition for [(3)H]-brevenol binding. After examining other site-specific compounds, it was determined that [(3)H]-brevenol binds to a site that is distinct from the other known sites including the brevetoxin site (site 5) although some interaction with site 5 is apparent. PMID:23789024

  20. Mo对石墨烯负载PtRu催化剂甲醇电氧化促进作用%Promoting effect of Mo in graphene supported PtRuMo catalyst for methanol electro-oxidation

    Institute of Scientific and Technical Information of China (English)

    曹小荣; 叶飞; 余林; 陈胜洲; 林维明

    2013-01-01

    Graphene supported PtRuMo catalyst (PtRuMo/G) was prepared by chemical reduction of graphite oxide (GO) and metal precursors with sodium borohydride at room temperature. The crystallographic properties and composition of the catalysts were characterized by X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis, and the catalytic activity and stability for methanol electro-oxidation were measured by electrochemical impedance spectroscopy (EIS), linear sweep voltammetries (LSV) and chronoamperometry (CA). The results show that the particle size of PtRuMo/G catalyst is about 4.7 nm, and the catalytic activity and stability of the PtRuMo /G catalyst are higher than those of PtRu/G catalyst.%采用Hummers液相氧化法合成氯化石墨,进而在室温下采用浸渍还原法制得石墨烯(G)负载的PtRu/G和PtRuMo/G催化剂.采用X射线衍射(XRD)、能量散射X射线谱(EDX)及扫描电镜(SEM)对氧化石墨和催化剂进行了表征,并使用交流阻抗法(EIS)、线性扫描伏安法(LSV)和计时安培法(CA)测试了催化剂催化甲醇电氧化的性能.结果表明:PtRuMo/G和PtRu/G催化剂的粒径分别为4.7、6.4 nm,PtRuMo/G催化剂催化甲醇电氧化的活性和稳定性都高于PtRu/G催化剂,Mo对PtRu/G催化剂的掺杂改性具有良好的促进作用.

  1. Primary structure determination of five sialylated oligosaccharides derived from bronchial mucus glycoproteins of patients suffering from cystic fibrosis. The occurrence of the NeuAc alpha(2----3)Gal beta(1----4)[Fuc alpha(1----3)] GlcNAc beta(1----.) structural element revealed by 500-MHz 1H NMR spectroscopy.

    Science.gov (United States)

    Lamblin, G; Boersma, A; Klein, A; Roussel, P; van Halbeek, H; Vliegenthart, J F

    1984-07-25

    The structure of sialylated carbohydrate units of bronchial mucins obtained from cystic fibrosis patients was investigated by 500-MHz 1H NMR spectroscopy in conjunction with sugar analysis. After subjecting the mucins to alkaline borohydride degradation, sialylated oligosaccharide-alditols were isolated by anion-exchange chromatography and fractionated by high performance liquid chromatography. Five compounds could be obtained in a rather pure state; their structures were established as the following: A-1, NeuAc alpha(2----3)Gal beta(1----4) [Fuc alpha(1----3)]GlcNAc beta(1----3)Gal-NAc-ol; A-2, NeuAc alpha(2----3)Gal beta(1----4)GlcNAc beta(1----6)-[GlcNAc beta (1----3)]GalNAc-o1; A-3, NeuAc alpha(2----3)Gal beta-(1----4)[Fuc alpha(1----3)]GlcNAc beta(1----3)Gal beta(1----3) GalNAc-o1; A-4, NeuAc alpha(2----3)Gal beta(1----4)[Fuc alpha(1----3)]Glc-NAc NAc beta(1----6)[GlcNAc beta(1----3)]GalNAc-o1; A-6,NeuAc alpha-(2----3) Gal beta(1----4)[Fuc alpha(1----3)]GlcNAc beta(1----6)[Gal beta-(1----4) GlcNAc beta(1----3)]GalNAc-o1. The simultaneous presence of sialic acid in alpha(2----3)-linkage to Gal and fucose in alpha(1----3)-linkage to GlcNAc of the same N-acetyllactosamine unit could be adequately proved by high resolution 1H NMR spectroscopy. This sequence constitutes a novel structural element for mucins.

  2. Facile and Scalable Preparation of Solid Silver Nanoparticles (<10 nm) for Flexible Electronics

    KAUST Repository

    Tai, Yan Long

    2015-07-02

    Metal conductive ink for flexible electroncs has exhibited a promising future recently. Here, an innovative strategy was reported to synthesize silver nanocolloid (2.5 ± 0.5 nm) and separate solid silver nanoparticles (<10 nm) effectively. Specifically, silver nitrate (AgNO3) was used as silver precursor, sodium borohydride (NaBH4) as reducing agent, fatty acid (CnH2n+1COOH) as dispersant agent, ammonia (NH3•H2O) and hydrochloride (HCl) as pH regulator and complexing agent in aqueous. The main mechanism is the solubility changes of fatty acid salts (CnH2n+1 COO-NH4+) and fatty acid (CnH2n+1 COOH) coated on the synthesized silver nanoparticles (NPs) in aqueous. This change determinates the suspension and precipitation of silver NPs directly. The results show that when n in dispersant is 12, and molar ratio (C12H24O2/AgNO3) is 1.0, the separation yield of silver NPs is up to 94.8 %. After sintered at 125 ℃ for 20 minutes, the as-prepared conductive silver nanoink (20 wt. %) presents a satisfactory resistivity (as low as 6.6 μΩ.cm on polyester-PET substrate), about 4 times the bulk silver. In addition, the efficacy of the as-prepared conductive ink was verified with the construction of radio frequency antenna by inkjet printing and conductive character pattern (Fudan-Fudan) by direct wiring, showing with excellent electrical performance.

  3. KDN-containing glycoprotein from loach skin mucus.

    Science.gov (United States)

    Nakagawa, H; Hama, Y; Sumi, T; Li, S C; Li, Y T

    2001-01-01

    It has been widely recognized that the mucus coat of fish plays a variety of important physical, chemical, and physiological functions. One of the major constituents of the mucus coat is mucus glycoprotein. We found that sialic acids in the skin mucus of the loach, Misgurnus anguillicaudatus, consisted predominantly of KDN. Subsequently, we isolated KDN-containing glycoprotein from loach skin mucus and characterized its chemical nature and structure. Loach mucus glycoprotein was purified from the Tris-HCl buffer extract of loach skin mucus by DEAE-cellulose chromatography, Nuclease P1 treatment, and Sepharose CL-6B gel filtration. The purified mucus glycoprotein was found to contain 38.5 KDN, 0.5% NeuAc, 25.0% GalNAc, 3.5% Gal, 0.5% GlcNAc and 28% amino acids. Exhaustive Actinase digestion of the glycoprotein yielded a glycopeptide with a higher sugar content and higher Thr and Ser contents. The molecular size of this glycopeptide was approximately 1/12 of the intact glycoprotein. These results suggest that approximately 11 highly glycosylated polypeptide units are linked in tandem through nonglycosylated peptides to form the glycoporotein molecule. The oligosaccharide alditols liberated from the loach mucus glycoprotein by alkaline borohydride treatment were separated by Sephadex G-25 gel filtration and HPLC. The purified sugar chains were analyzed b --> 6GalNAc-ol, KDNalpha2 --> 3(GalNAcbeta1 --> 14)GalNAc-ol, KDNalpha2 --> 6(GalNAcalpha1 --> 3)GalNAc-ol, KDNalpha2 --> 6(Gal3alpha1--> 3)GalNAc-ol, and NeuAcalpha2 --> 6Gal NAc-ol. It is estimated that one loach mucus glycoprotein molecule contains more than 500 KDN-containing sugar chains that are linked to Thr and Ser residues of the protein core through GalNAc.

  4. Phytochemical profiles and antioxidant activities in six species of ramie leaves.

    Directory of Open Access Journals (Sweden)

    Yongsheng Chen

    Full Text Available Increased consumption of vegetables or plant food has been associated with decreased risk of developing major chronic diseases, such as cancers, diabetes, cardiovascular diseases, and age-related functional decline. Ramie leaves are rich in phenolics and flavonoids, which have been suggested for human health benefits. Phenolic contents, flavonoid contents, phenolic compounds, and anti-cancer properties in six species of ramie leaves were analyzed by Folin-reagent method, sodium borohydride/chloranil-based assay (SBC, HPLC method and antiproliferation, cytoxicity, respectively. Antioxidant activities were measured through peroxyl radical scavenging capacity (PSC method, oxygen radical absorbance capacity (ORAC method, and cellular antioxidant activity (CAA. Research indicated that Boehmeria penduliflora contained the highest total phenolic content (2313.7±27.28 mg GAE/100 g FW, and flavonoid content (1682.4±27.70 mg CAE/100 g FW. Boehmeria tricuspis showed the highest PSC value (9574.8±117.63 µM vit. C equiv./100 g FW, while Boehmeria penduliflora indicated the highest ORAC value (330.44±16.88 µmol Trolox equiv./g FW. The antioxidant activities were correlated with phenolic contents and flavonoid contents. Boehmeria tricuspis had the highest antiproliferative capacity with the lowest EC₅₀ (4.11±0.19 mg/mL. The results for the analyzed ramie for CAA were significantly different from each other (p<0.05, Boehmeria tricuspis had the highest CAA value (133.63±7.10 µmol QE/100 g. Benzoic acid, 4-coumaric acid, caffeic acid, and ferulic acid were the dominant phenolic ingredients in the ramie leaves according to HPLC analysis. Our research is the first report to study the phytochemical profiles and antioxidant activities in different species of ramie leaves for their health benefit.

  5. Green method for ultrasensitive determination of Hg in natural waters by electrothermal-atomic absorption spectrometry following sono-induced cold vapor generation and 'in-atomizer trapping'

    International Nuclear Information System (INIS)

    Sono-induced cold vapor generation (SI-CVG) has been used for the first time in combination with a graphite furnace atomizer for determination of Hg in natural waters by electrothermal-atomic absorption spectrometry after in situ trapping onto a noble metal-pretreated platform (Pd, Pt or Rh) inserted into a graphite tube. The system allows 'in-atomizer trapping' of Hg without the use of conventional reduction reactions based on sodium borohydride or tin chloride in acid medium for cold vapor generation. The sono-induced reaction is accomplished by applying ultrasound irradiation to the sample solution containing Hg(II) in the presence of an organic compound such as formic acid. As this organic acid is partly degraded upon ultrasound irradiation to yield CO, CO2, H2 and H2O, the amount of lab wastes is minimized and a green methodology is achieved. For this purpose, experimental variables influencing the generation/trapping process are fully investigated. The limit of detection for a 10 min trapping time and 10 mL sample volume was 0.03 μg L-1 (Integrated absorbance) and the repeatability expressed as relative standard deviation was about 3%. Carbonates and chlorides at 100 mg L-1 level caused a signal depression by 20-30%. The enhanced trapping efficiency observed with the sono-induced cold vapor generation as compared with 'in-atomizer trapping' methods employing chemical vapor generation is discussed. A reaction pathway for SI-CVG is proposed on the basis of the current knowledge for synthesis of noble metal nanoparticles by ultrasound

  6. A glassy carbon electrode modified with bismuth nanotubes in a silsesquioxane framework for sensing of trace lead and cadmium by stripping voltammetry

    International Nuclear Information System (INIS)

    Single-walled bismuth nanotubes (sw-BiNTs) were self-assembled with octa(3-aminopropyl) silsesquioxane as a framework and to govern morphology. Deposited on a glassy carbon electrode (GCE), the sw-BiNTs were used for the simultaneous analysis of Pb(II) and Cd(II) by square wave stripping voltammetry. The sw-BiNTs were prepared by (a) coordination interaction between the amino groups of the silsesquioxane and the Bi(III) ions, and by (b) reduction with sodium borohydride. Transmission electron microscopy images revealed single-walled tubular structures with diameters of ∼4–6 nm, and with lengths of several hundreds nanometers. GCEs modified with such sw-BiNTs perform much better than bare GCEs in stripping analysis of Pb(II) and Cd(II). The effects of adsorption quantity of sw-BiNTs, solution pH, pulse amplitude, and pulse width were optimized. The modified electrode was then used for the analysis of Pb(II) and Cd(II) in a linear response range from 0.4 to 6 μM with a sensitivity of 4.692 μA μM−1 and 3.835 μA μM−1, and detection limits of 1 nM and 5 nM, respectively. The method was successfully applied to the analysis of Pb(II) and Cd(II) in toy leachates, and the results were in good agreement with those obtained with atomic absorption spectrometry. Sensitivity and detection limits were compared with other voltammetric methods, and the sw-BiNTs are deemed to be an attractive alternative for practical applications. Other features of the electrode include low costs, a well reproducible nanostructure, and ease of scale-up of the fabrication process. (author)

  7. Covalent attachment of cell-adhesive peptide Gly-Arg-Gly-Asp (GRGD) to poly(etheretherketone) surface by tailored silanization layers technique

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Yanyan [Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Xiong, Chengdong [Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041 (China); Li, Xiaoyu [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Zhang, Lifang, E-mail: zhanglfcioc@163.com [Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041 (China)

    2014-11-30

    Highlights: • The carbonyl groups on PEEK surface were effectively reduced to hydroxyl groups using sodium borohydride. • Silanization layers technique was employed to immobilize the cell-adhesive peptide Gly-Arg-Gly-Asp (GRGD) on hydroxylation-pretreated PEEK sheet surface by covalent chemical attachment. • XPS, surface profiler and water contact angle measurements proved the presence of GRGD on PEEK surface. • Osteoblast-like cells (MC3T3-E1) attachment and proliferation were improved effectively on GRGD-modified PEEK surface. - Abstract: Poly(etheretherketone) (PEEK) is a rigid semicrystalline polymer that combines excellent mechanical properties, broad chemical resistance and bone-like stiffness and is widely used in biomedical fields. However, PEEK is naturally bioinert, leading to limited biomedical applications, especially when a direct bone-implant osteointegration is desired. In this study, a three-step reaction procedure was employed to immobilize the cell-adhesive peptide Gly-Arg-Gly-Asp (GRGD) on the surface of PEEK sheet by covalent chemical attachment to favor cell adhesion and proliferation. First, hydroxylation-pretreated PEEK surfaces were silanized with 7-Oct-1-enyltrichlorosilane (OETS) in dry cyclohexane, resulting in a silanization layer with terminal ethenyl. Second, the terminal ethylenic double bonds of the silanization layer on PEEK surface were converted to carboxyl groups through acidic potassium manganate oxidation. Finally, GRGD was covalently attached by carbodiimide mediated condensation between the carboxyl on PEEK surface and amine presents in GRGD. X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, surface profiler and water contact angle measurements were applied to characterize the modified surfaces. The effect of cells attachment and proliferation on each specimen was investigated. Pre-osteoblast cells (MC3T3-E1) attachment, spreading and proliferation

  8. Selection and applicability of quenching agents for the analysis of polar iodinated disinfection byproducts.

    Science.gov (United States)

    Gong, Tingting; Tao, Yuxian; Xian, Qiming

    2016-11-01

    Iodide is widely present in drinking water sources as well as wastewater effluents. Chlorination and chloramination are the most commonly used disinfection methods. During chlorination or chloramination of drinking water/wastewater effluents, iodide may be oxidized to hypoiodous acid, which may further react with organic matter to form iodinated disinfection byproducts (DBPs). Recently, several new polar iodinated DBPs have been identified in drinking water as well as chlorinated wastewater effluents, and they have drawn increasing concerns due to their high toxicity. In DBPs studies, the selection of an appropriate quenching agent is critical to prevent further formation or any decomposition of DBPs during the holding time between sample collection and analysis. A previous study reported the applicability of different quenching agents for the analysis of various categories of chlorinated and brominated DBPs. But the applicability of quenching agents for the analysis of polar iodinated DBPs has not been reported. In this study, four different quenching agents (sodium sulfite, sodium thiosulfate, ascorbic acid and sodium borohydride) were tested for their suitability for the analysis of polar iodinated DBPs, and ascorbic acid was selected as the suitable quenching agent. Furthermore, it was found that ascorbic acid was applicable for the analysis of polar iodinated DBPs under the quenching agent doses of 0-0.42 mmol/L (stoichiometric amounts equivalent to 0-30 mg/L Cl2), contact times within 24 h, and pHs in the range of 6-8. Therefore, ascorbic acid was a widely applicable quenching agent for the analysis of polar iodinated DBPs under various conditions. PMID:27557432

  9. Nanostructured, complex hydride systems for hydrogen generation

    Directory of Open Access Journals (Sweden)

    Robert A. Varin

    2015-02-01

    Full Text Available Complex hydride systems for hydrogen (H2 generation for supplying fuel cells are being reviewed. In the first group, the hydride systems that are capable of generating H2 through a mechanical dehydrogenation phenomenon at the ambient temperature are discussed. There are few quite diverse systems in this group such as lithium alanate (LiAlH4 with the following additives: nanoiron (n-Fe, lithium amide (LiNH2 (a hydride/hydride system and manganese chloride MnCl2 (a hydride/halide system. Another hydride/hydride system consists of lithium amide (LiNH2 and magnesium hydride (MgH2, and finally, there is a LiBH4-FeCl2 (hydride/halide system. These hydride systems are capable of releasing from ~4 to 7 wt.% H2 at the ambient temperature during a reasonably short duration of ball milling. The second group encompasses systems that generate H2 at slightly elevated temperature (up to 100 °C. In this group lithium alanate (LiAlH4 ball milled with the nano-Fe and nano-TiN/TiC/ZrC additives is a prominent system that can relatively quickly generate up to 7 wt.% H2 at 100 °C. The other hydride is manganese borohydride (Mn(BH42 obtained by mechano-chemical activation synthesis (MCAS. In a ball milled (2LiBH4 + MnCl2 nanocomposite, Mn(BH42 co-existing with LiCl can desorb ~4.5 wt.% H2 at 100 °C within a reasonable duration of dehydrogenation. Practical application aspects of hydride systems for H2 generation/storage are also briefly discussed.

  10. Determination of arsenic metabolic complex excreted in human urine after administration of sodium 2,3-dimercapto-1-propane sulfonate.

    Science.gov (United States)

    Gong, Zhilong; Jiang, Guifeng; Cullen, William R; Aposhian, H Vasken; Le, X Chris

    2002-10-01

    Sodium 2,3-dimercapto-1-propane sulfonate (DMPS) has been used to treat acute arsenic poisoning. Presumably DMPS functions by chelating some arsenic species to increase the excretion of arsenic from the body. However, the excreted complex of DMPS with arsenic has not been detected. Here we describe a DMPS complex with monomethylarsonous acid (MMA(III)), a key trivalent arsenic in the arsenic methylation process, and show the presence of the DMPS-MMA(III) complex in human urine after the administration of DMPS. The DMPS-MMA(III) complex was characterized using electrospray tandem mass spectrometry and determined by using HPLC separation with hydride generation atomic fluorescence detection (HGAFD). The DMPS-MMA(III) complex did not form a volatile hydride with borohydride treatment. On-line digestion with 0.1 M sodium hydroxide following HPLC separation decomposed the DMPS-MMA(III) complex and allowed for the subsequent quantification by hydride generation atomic fluorescence. Arsenite (As(III)), arsenate (As(V)), monomethylarsonic acid (MMA(V)), dimethylarsinic acid (DMA(V)), MMA(III), and DMPS-MMA(III) complex were analyzed in urine samples from human subjects collected after the ingestion of 300 mg of DMPS. The administration of DMPS resulted in a decrease of the DMA(V) concentration and an increase of the MMA(V) concentration excreted in the urine, confirming the previous results. The finding of the DMPS-MMA(III) complex in human urine after DMPS treatment provides an explanation for the inhibition of arsenic methylation by DMPS. Because MMA(III) is the substrate for the biomethylation of arsenic from MMA(V) to DMA(V), the formation of DMPS-MMA(III) complex would reduce the availability of MMA(III) for the subsequent biomethylation. PMID:12387631

  11. 3-甲氧基-4-苄氧基苯乙胺盐酸盐的合成%Synthesis of 3-Methoxy-4-benzyloxyphenethylamine Hydrochloride

    Institute of Scientific and Technical Information of China (English)

    惠帅; 姜奇; 许佑君

    2012-01-01

    Vanillin was first treated with benzyl bromide for the benzylation, then the aldehyde was condensed with nitromethane. The product of the condensation was then reduced by sodium borohydride in the presence of boron trifluoride etherate to give 3-methoxy-4-benzyloxyphenethylamine which was lastly treated with hydrochloric ethyl acetate to give the final compound. The effects of reagent mole ratio, reaction temperature and reaction time on the yield of the condensation were studied, and also the effects of reducing agent proportion and reaction time on the yield of the reduction were studied. The total yield could reach up to 79.4% in four steps, and the structure of the target compound was confirmed by means of ESI-MS and 1 HNMR.%以香草醛为原料,先与溴苄合成苄醚,再与硝基甲烷缩合,经NaBH4/BF3· Et2O还原得相应的芳基乙胺,最后与氯化氢的乙酸乙酯溶液成盐,合成了目标产物3-甲氧基-4-苄氧基苯乙胺盐酸盐.考察了缩合反应的投料比、反应温度和反应时间,还原反应的还原剂用量和反应时间对反应收率的影响.优化后4步反应的总收率为79.4%,产品经ESI-MS和1HNMR确证了结构.

  12. Determination of trace mercury in surface water by atomic fluorescence spectrometry%原子荧光光度法测定地表水中的痕量汞

    Institute of Scientific and Technical Information of China (English)

    潘腊青; 章维维; 池怡; 周姗

    2013-01-01

    以硫酸-高锰酸钾加热消解水样,低浓度硼氢化钾作为还原剂,运用 A FS -9230双道原子荧光光度计,采用顺序注射-冷蒸气发生-原子荧光光谱法,测定地表水中的痕量汞。检出限为0.012μg/L ,回收率为90%~110%,RSD小于10.0%,该法具有灵敏度高,精密度好,干扰少和操作简单方便等优点,同时对方法的质量控制进行了探讨。%Heating and digestion of water samples by sulfuric acid and potassium permanganate ,low concentration potassium borohydride as the reducing agent ,using AFS-9230 double-channel atomic fluo-rescence spectrometry ,determination of trace mercury in surface water with sequential injection-cold vapor generation-atomic fluorescence spectrometry was carried out. The detection limit is 0.012μg/L ,the rate of recovery is 90%-110% ,RSD<10.0%. The advantages of the method are of high sensitivity ,good preci-sion ,less interference ,simple and convenient operation. At the same time ,the aspect of quality control w as discussed.

  13. Dinuclear Zinc(II) Macrocyclic Complex as Receptor for Selective Fluorescence Sensing of Pyrophosphate.

    Science.gov (United States)

    Mesquita, Lígia M; André, Vânia; Esteves, Catarina V; Palmeira, Tiago; Berberan-Santos, Mário N; Mateus, Pedro; Delgado, Rita

    2016-03-01

    A new diethylenetriamine-derived macrocycle known as L, bearing 2-methylquinoline arms and containing m-xylyl spacers, was prepared in good yield by a one-pot [2 + 2] Schiff base condensation procedure, followed by reduction with sodium borohydride. Up to now this is the first hexaazamacrocycle with appended fluorophore units. Single-crystal X-ray diffraction determination of the dinuclear zinc(II) complex of L showed that metal centers are located at about 7.20(2) Å from one another. This complex exhibits only weak fluorescence in aqueous solution, but the addition of 1 equiv of pyrophosphate (PPi) caused a 21-fold enhancement of the fluorescence intensity. The sensor response is linear up to a value of 10 μM HPPi(3-) and has a detection limit of 300 nM. The receptor behaves as a highly selective sensor for pyrophosphate as other anions, including phosphate, phenylphosphate (PhP), adenosine monophosphate (AMP), adenosine diphosphate (ADP), and adenosine triphosphate (ATP), failed to induce any fluorescence change and practically do not affect the fluorescence intensity of the sensor in the presence of HPPi(3-). Competition titrations carried out in aqueous solution at pH 7.4 [in 20 mM 3-(N-morpholino)propanesulfonic acid (MOPS) buffer] by spectrofluorometry revealed a high association constant value of 6.22 log units for binding of PPi by the dinuclear zinc(II) receptor, one of the highest reported values for colorimetric/fluorometric sensors able to work under real aqueous physiological conditions, while association constant values for binding of the other phosphorylated substrates are in the 5.51-4.03 log unit range. PMID:26871612

  14. Research on Synthesis of Ethylenebisstearamide%乙撑双硬脂酸酰胺的合成

    Institute of Scientific and Technical Information of China (English)

    胡丹; 荀育军; 刘清泉

    2013-01-01

    Ethylenebisstearamide (EBS) was prepared by condensation of stearic acid and ethylenediamine at high temperature.The influencing factors on the reaction were investigated and optimized as following:n (stearic acid 1840)∶n(ethylenediamine)=2∶1.15,mixture of phosphoric acid and phosphorous acid as the catalyst (0.92% mass of stearic acid),m (phosphoric acid)∶m (phosphorous acid)=3∶10,sodium borohydride as the antioxidant (0.21% mass of stearic acid),salting temperature 100~110℃,salting time 2 h,dehydration temperature 190~200 ℃,dehydration time 5~6 h.The white product was obtained with melting point of 143~150℃.%以硬脂酸和乙二胺为原料在高温下脱水得到乙撑双硬酸脂酰胺产品.研究了硬脂酸种类、反应物料比、催化剂、抗氧剂、反应温度和反应时间对产品的影响.适宜的工艺条件为:n(硬脂酸1840)∶n(乙二胺)=2∶1.15,磷酸与亚磷酸为复配催化剂(硬脂酸质量的0.92%),m(磷酸)∶m(亚磷酸)=3∶10,硼氢化钠做抗氧剂(硬脂酸质量的0.21%),成盐温度100~110℃,成盐时间2h,脱水温度190~200℃,脱水时间5~6h,此工艺条件下得到白色产品,m.p.143~150℃.

  15. Graphene oxide/α-Bi(2)O(3) composites for visible-light photocatalysis, chemical catalysis, and solar energy conversion.

    Science.gov (United States)

    Som, Tirtha; Troppenz, Gerald V; Wendt, R Robert; Wollgarten, Markus; Rappich, Jörg; Emmerling, Franziska; Rademann, Klaus

    2014-03-01

    The growing challenges of environmental purification by solar photocatalysis, precious-metal-free catalysis, and photocurrent generation in photovoltaic cells receive the utmost global attention. Here we demonstrate a one-pot, green chemical synthesis of a new stable heterostructured, ecofriendly, multifunctional microcomposite that consists of α-Bi2 O3 microneedles intercalated with anchored graphene oxide (GO) microsheets (1.0 wt %) for the above-mentioned applications on a large economical scale. The bare α-Bi2 O3 microneedles display two times better photocatalytic activities than commercial TiO2 (Degussa-P25), whereas the GO-hybridized composite exhibits approximately four to six times enhanced photocatalytic activities than the neat TiO2 photocatalyst in the degradation of colored aromatic organic dyes (crystal violet and rhodamine 6G) under visible-light irradiation (300 W tungsten lamp). The highly efficient activity is associated with the strong surface adsorption ability of GO for aromatic dye molecules, the high carrier acceptability, and the efficient electron-hole pair separation in Bi2 O3 by individual adjoining GO sheets. The introduction of Ag nanoparticles (2.0 wt %) further enhances the photocatalytic performance of the composite over eightfold because of a plasmon-induced electron-transfer process from Ag nanoparticles through the GO sheets into the conduction band of Bi2 O3 . The new composites are also catalytically active and catalyze the reduction of 4-nitrophenol to 4-aminophenol in the presence of borohydride ions. Photoanodes assembled from GO/α-Bi2 O3 and Ag/GO/α-Bi2 O3 composites display an improved photocurrent response (power conversion efficiency ∼20 % higher) over those prepared without GO in dye-sensitized solar cells. PMID:24578169

  16. Estudo cinético da redução da massa molar do poli(3-hidroxibutirato-co-3-hidroxivalerato (PHBHV Kinetic study of the molecular weight reduction of poly (3-hydroxybutirate-co-3-hydroxyvalerate (PHBHV

    Directory of Open Access Journals (Sweden)

    Sérgio R. Montoro

    2010-01-01

    Full Text Available Neste trabalho foi realizado um estudo cinético da redução da massa molar do poli(3-hidroxibutirato-co-3-hidroxivalerato (PHBHV em três diferentes metodologias: hidrólise ácida com ácido clorídrico, transesterificação com hexilenoglicol ou etilenoglicol e redução na presença do borohidreto de sódio (NaBH4. Foram investigados os parâmetros de processo: tempo, temperatura, tipo e concentração de catalisadores. Os resultados de redução de massa molar foram analisados pelo modelo cinético de ordem n. A redução com NaBH4 foi mais eficiente do ponto de vista cinético, tendo em vista os parâmetros: constante de reação k e energia de ativação (Ea, uma vez que os valores observados foram significativamente maiores em comparação com os calculados para os demais métodos.In this work a kinetic study was carried out of the molecular weight reduction of poly(3-hydroxybutirate-co-3-hydroxyvalerate (PHBHV in three different methodologies: acid hydrolysis using hydrochloric acid, transesterification with ethylene glycol or hexylene glycol and reduction in the presence of sodium borohydride (NaBH4. The following process parameters were investigated: time, temperature, type and concentration of catalysts. The results of molecular weight reduction were fitted with a n-order kinetic model. The kinetics analysis has shown that the NaBH4 reduction was the most efficient in terms of reaction rate in comparison with the other methods.

  17. Development of solvent-free ambient mass spectrometry for green chemistry applications.

    Science.gov (United States)

    Liu, Pengyuan; Forni, Amanda; Chen, Hao

    2014-04-15

    Green chemistry minimizes chemical process hazards in many ways, including eliminating traditional solvents or using alternative recyclable solvents such as ionic liquids. This concept is now adopted in this study for monitoring solvent-free reactions and analysis of ionic liquids, solids, and catalysts by mass spectrometry (MS), without using any solvent. In our approach, probe electrospray ionization (PESI), an ambient ionization method, was employed for this purpose. Neat viscous room-temperature ionic liquids (RTILs) in trace amounts (e.g., 25 nL) could be directly analyzed without sample carryover effect, thereby enabling high-throughput analysis. With the probe being heated, it can also ionize ionic solid compounds such as organometallic complexes as well as a variety of neat neutral solid chemicals (e.g., amines). More importantly, moisture-sensitive samples (e.g., [bmim][AlCl4]) can be successfully ionized. Furthermore, detection of organometallic catalysts (including air-sensitive [Rh-MeDuPHOS][OTf]) in ionic liquids, a traditionally challenging task due to strong ion suppression effect from ionic liquids, can be enabled using PESI. In addition, PESI can be an ideal approach for monitoring solvent-free reactions. Using PESI-MS, we successfully examined the alkylation of amines by alcohols, the conversion of pyrylium into pyridinium, and the condensation of aldehydes with indoles as well as air- and moisture-sensitive reactions such as the oxidation of ferrocene and the condensation of pyrazoles with borohydride. Interestingly, besides the expected reaction products, the reaction intermediates such as the monopyrazolylborate ion were also observed, providing insightful information for reaction mechanisms. We believe that the presented solvent-free PESI-MS method would impact the green chemistry field.

  18. Isolation of a very high molecular weight polylactosamine from an ovarian cyst mucin of blood group

    Energy Technology Data Exchange (ETDEWEB)

    Wu, A.S.S.; Bush, C.A.

    1986-05-01

    Treatment of a blood group A active ovarian cyst mucin glycoprotein with alkaline borohydride under conditions expected to cleave-O-glycosidically linked carbohydrate chains releases a polysaccharide of average molecular weight 25,000 daltons. It contains no peptide or mannose at the 1% level and carbohydrate analysis gives fuc:galNAc:gal:glcNAc in the ratio of 1:1:2.5:2.5. The /sup 13/C and /sup 1/H NMR spectra show that the polysaccharide has non-reducing terminal side chains of the structure galNAc(..cap alpha..-1 ..-->.. 3)(fuc(..cap alpha..-1 ..-->.. 2)) gal(..beta..-1 ..-->.. 3) glcNAc (i.e. a type 1 chain). Periodate oxidation removes all the fucose and galNAc from the non-reducing terminal but leaves intact the backbone composed of ..beta..-linked gal and glcNAc as would be expected for a polylactosamine. They conclude that this is a high molecular weight polylactosamine which is related to the asparagine linked polylactosamine chains of cell surface glycoproteins which have been implicated in cell differentiation. However, the blood group A polysaccharide from the ovarian cyst mucin is unique in several respects. It has a much larger molecular weight than even the erythroglycan of the red cell membrane protein, band 3, and is linked to the protein by an -O-glycosidic bond rather than the -N-asparagine linkage of the previously known polylactosamines which have a trimannosyl core. Its blood group A side chains are on a type one core rather than type 2 which is found on other polylactosamines.

  19. Impact of ZnO and Ag Nanoparticles on Bacterial Growth and Viability

    Science.gov (United States)

    Olson, M. S.; Digiovanni, K. A.

    2007-12-01

    Hundreds of consumer products containing nanomaterials are currently available in the U.S., including computers, clothing, cosmetics, sports equipment, medical devices and product packaging. Metallic nanoparticles can be embedded in or coated on product surfaces to provide antimicrobial, deodorizing, and stain- resistant properties. Although these products have the potential to provide significant benefit to the user, the impact of these products on the environment remains largely unknown. The purpose of this project is to study the effect of metallic nanoparticles released to the environment on bacterial growth and viability. Inhibition of bacterial growth was tested by adding doses of suspended ZnO and Ag nanoparticles into luria broth prior to inoculation of Escherichia coli cells. ZnO particles (approximately 40 nm) were obtained commercially and Ag particles (12-14 nm) were fabricated by reduction of silver nitrate with sodium borohydride. Toxicity assays were performed to test the viability of E. coli cells exposed to both ZnO and Ag nanoparticles using the LIVE/DEAD BacLight bacterial viability kit (Invitrogen). Live cells stain green whereas cells with compromised membranes that are considered dead or dying stain red. Cells were first grown, stained, and exposed to varying doses of metallic nanoparticles, and then bacterial viability was measured hourly using fluorescence microscopy. Results indicate that both ZnO and Ag nanoparticles inhibit the growth of E. coli in liquid media. Preliminary results from toxicity assays confirm the toxic effect of ZnO and Ag nanoparticles on active cell cultures. Calculated death rates resulting from analyses of toxicity studies will be presented.

  20. Sensitive determination of As (III) and As (V) by magnetic solid phase extraction with Fe@polyethyleneimine in combination with hydride generation atomic fluorescence spectrometry.

    Science.gov (United States)

    Zhou, Qingxiang; Zheng, Zhenwen; Xiao, Junping; Fan, Huili

    2016-08-15

    The magnetic nanomaterial Fe@polyethyleneimine (Fe@PEI) was successfully synthesized and used as an effective adsorbent material for magnetic solid phase extraction(MSPE) of As(III) and As(V) from water samples. Fe@SiO2 nanoparticles were prepared by one pot synthetic method using a borohydride reduction method, then modified with (3-chloropropyl)trimethoxysilane to obtain Fe@SiO2-Cl by chloropropylation, which was reacted with PEI to achieve Fe@polyethyleneimine (Fe@PEI). The microstructure and morphology of Fe@PEI were characterized by transmission electron microscoscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). The experimental results showed that Fe@PEI demonstrated excellent adsorption for As(III) and As(V). Based on this fact, the determination method for these two arsenic species earned good limits of detection (LODs) of 0.002μgL(-1) and wide calibration curves in the concentration range from 0.008 to 0.2μgL(-1). The precisions of As (III) and As (V)were 1.95% and 2.55% (RSD, n=6), respectively. The proposed method was validated with real samples and the spiked recoveries were in the range of 82.7-98.3% and the accuracies were in the range of 2-13.3%. The results demonstrated that the developed MSPE method had good advantages such as simplicity, rapid separation, low cost, easy to reuse and high-quality analytical performances, which made it attractive for rapid and efficient extraction of inorganic arsenic species in the environmental water samples. PMID:27260453

  1. Topological dispositions of lysine α380 and lysine γ486 in the acetylcholine receptor from Torpedo californica

    International Nuclear Information System (INIS)

    The locations have been determined, with respect to the plasma membrane, of lysine α380 and lysine γ486 in the α subunit and the γ subunit, respectively, of the nicotinic acetylcholine receptor from Torpedo californica. Immunoadsorbents were constructed that recognize the carboxy terminus of the peptide GVKYIAE released by proteolytic digestion from positions 378-384 in the amino acid sequence of the α subunit of the acetylcholine receptor and the carboxy terminus of the peptide KYVP released by proteolytic digestion from positions 486-489 in the amino acid sequence of the γ subunit. They were used to isolate these peptides from proteolytic digests of polypeptides from the acetylcholine receptor. Sealed vesicles containing the native acetylcholine receptor were labeled with pyridoxal phosphate and sodium [3H]-borohydride. The effect of saponin on the incorporation of pyridoxamine phosphate into lysine α380 and lysine γ486 from the acetylcholine receptor in these vesicles was assessed with the immunoadsorbents. The conclusions that follow from these results are that lysine α380 is on the inside surface of a vesicle and lysine γ486 is on the outside surface. Because a majority (85%) of the total binding sites for α-bungarotoxin bind the toxin in the absence of saponin, the majority of the vesicles are right side out with the inside of the vesicle corresponding to the cytoplasmic surface and the outside of the vesicle corresponding to the extracytoplasmic, synaptic surface. Because lysine α380 and lysine γ486 lie on opposite sides of the membrane, a membrane-spanning segment must be located between the two positions occupied by these two amino acids in the common sequence of a polypeptide of the acetylcholine receptor

  2. Topological dispositions of lysine. alpha. 380 and lysine. gamma. 486 in the acetylcholine receptor from Torpedo californica

    Energy Technology Data Exchange (ETDEWEB)

    Dwyer, B.P. (Univ. of California, San Diego, La Jolla (USA))

    1991-04-23

    The locations have been determined, with respect to the plasma membrane, of lysine {alpha}380 and lysine {gamma}486 in the {alpha} subunit and the {gamma} subunit, respectively, of the nicotinic acetylcholine receptor from Torpedo californica. Immunoadsorbents were constructed that recognize the carboxy terminus of the peptide GVKYIAE released by proteolytic digestion from positions 378-384 in the amino acid sequence of the {alpha} subunit of the acetylcholine receptor and the carboxy terminus of the peptide KYVP released by proteolytic digestion from positions 486-489 in the amino acid sequence of the {gamma} subunit. They were used to isolate these peptides from proteolytic digests of polypeptides from the acetylcholine receptor. Sealed vesicles containing the native acetylcholine receptor were labeled with pyridoxal phosphate and sodium ({sup 3}H)-borohydride. The effect of saponin on the incorporation of pyridoxamine phosphate into lysine {alpha}380 and lysine {gamma}486 from the acetylcholine receptor in these vesicles was assessed with the immunoadsorbents. The conclusions that follow from these results are that lysine {alpha}380 is on the inside surface of a vesicle and lysine {gamma}486 is on the outside surface. Because a majority (85%) of the total binding sites for {alpha}-bungarotoxin bind the toxin in the absence of saponin, the majority of the vesicles are right side out with the inside of the vesicle corresponding to the cytoplasmic surface and the outside of the vesicle corresponding to the extracytoplasmic, synaptic surface. Because lysine {alpha}380 and lysine {gamma}486 lie on opposite sides of the membrane, a membrane-spanning segment must be located between the two positions occupied by these two amino acids in the common sequence of a polypeptide of the acetylcholine receptor.

  3. Antifungal activity of gold nanoparticles prepared by solvothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Tokeer, E-mail: tahmad3@jmi.ac.in [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Wani, Irshad A.; Lone, Irfan H.; Ganguly, Aparna [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Manzoor, Nikhat; Ahmad, Aijaz [Department of Biosciences, Jamia Millia Islamia, New Delhi 110025 (India); Ahmed, Jahangeer [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Al-Shihri, Ayed S. [Department of Chemistry, Faculty of Science, King Khalid University, Abha 61413, P.O. Box 9004 (Saudi Arabia)

    2013-01-15

    Graphical abstract: Gold nanoparticles (7 and 15 nm) of very high surface area (329 and 269 m{sup 2}/g) have been successfully synthesized through solvothermal method by using tin chloride and sodium borohydride as reducing agents. As-prepared gold nanoparticles shows very excellent antifungal activity against Candida isolates and activity increases with decrease in the particle size. Display Omitted Highlights: ► Effect of reducing agents on the morphology of gold nanoparticles. ► Highly uniform and monodisperse gold nanoparticles (7 nm). ► Highest surface area of gold nanoparticles (329 m{sup 2/}g). ► Excellent antifungal activity of gold nanoparticles against Candida strains. -- Abstract: Gold nanoparticles have been successfully synthesized by solvothermal method using SnCl{sub 2} and NaBH{sub 4} as reducing agents. X-ray diffraction studies show highly crystalline and monophasic nature of the gold nanoparticles with face centred cubic structure. The transmission electron microscopic studies show the formation of nearly spherical gold nanoparticles of average size of 15 nm using SnCl{sub 2}, however, NaBH{sub 4} produced highly uniform, monodispersed and spherical gold nanoparticles of average grain size of 7 nm. A high surface area of 329 m{sup 2}/g for 7 nm and 269 m{sup 2}/g for 15 nm gold nanoparticles was observed. UV–vis studies assert the excitations over the visible region due to transverse and longitudinal surface plasmon modes. The gold nanoparticles exhibit excellent size dependant antifungal activity and greater biocidal action against Candida isolates for 7 nm sized gold nanoparticles restricting the transmembrane H{sup +} efflux of the Candida species than 15 nm sized gold nanoparticles.

  4. Identifying the nature of interaction between LiBH{sub 4} and two-dimensional substrates: DFT study with van der Waals correction

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Sung Hoon; Lee, Young-Su; Cho, Young Whan, E-mail: oze@kist.re.kr

    2014-02-25

    Highlights: • The interaction between LiBH{sub 4} and 2-dimensional substrates was examined using DFT. • Monomer LiBH{sub 4}–2D interface interaction is governed by the dipole of LiBH{sub 4} monomer. • Bulk LiBH{sub 4}–2D interface interaction is dominated by the dispersion forces. • Binding energy of bulk LiBH{sub 4}–2D interface is comparable to LiBH{sub 4} surface energy. -- Abstract: Addressing the nature of interaction at the LiBH{sub 4}−carbon interface is the key to unveiling mechanism for the carbon-facilitated desorption of lithium borohydride (LiBH{sub 4}). Density functional theory calculations, taking into account the long range dispersion forces, have been performed to explore the interaction between LiBH{sub 4}, in the form of either a monomer unit or a crystalline bulk, and two-dimensional (2D) substrate, represented by graphene and hexagonal boron nitride. At the monomer−2D contact, the permanent dipole of LiBH{sub 4} induces polarization of the π electrons of the 2D, and the resultant permanent dipole–induced dipole attraction becomes the main source of binding. At the bulk−2D interface, van der Waals attraction dominates the interfacial binding rather than the dipole–dipole attraction. The absolute values of the calculated interface energy match closely with the surface energy of pristine (0 0 1) LiBH{sub 4}, hinting that the energy released by the formation of the interface has enough magnitude to overcome the surface energy of LiBH{sub 4}.

  5. Are extracted materials truly representative of original samples? Impact of C18 extraction on CDOM optical and chemical properties

    Directory of Open Access Journals (Sweden)

    Andrea A Andrew

    2016-02-01

    Full Text Available Some properties of dissolved organic matter (DOM and chromophoric dissolved organic matter (CDOM can be easily measured directly on whole waters, while others require sample concentration and removal of natural salts. To increase CDOM content and eliminate salts, solid phase extraction is often employed. Biases following extraction and elution are inevitable, thus raising the question of how truly representative the extracted material is of the original. In this context, we investigated the wavelength dependence of extraction efficiency for C18 cartridges with respect to CDOM optical properties using samples obtained from the Middle Atlantic Bight (MAB and the Equatorial Atlantic Ocean (EAO. Further, we compared the optical changes of C18 extracts and the corresponding whole water following chemical reduction with sodium borohydride (NaBH4.C18 cartridges preferentially extracted long-wavelength absorbing/emitting material for samples impacted by riverine input. Extraction efficiency overall decreased with offshore distance away from riverine input. Spectral slopes of C18-OM samples were also almost always lower than those of their corresponding CDOM samples supporting the preferential extraction of higher molecular weight absorbing material. The wavelength dependence of the optical properties (absorption, fluorescence emission and quantum yield of the original water samples and their corresponding extracted material were very similar. C18 extracts and corresponding water samples further exhibited comparable optical changes following NaBH4 reduction, thus suggesting a similarity in nature (structure of the optically active extracted material, independent of geographical locale. Altogether, these data suggested a strong similarity between C18 extracts and corresponding whole waters, thus indicating that extracts are representative of the CDOM content of original waters.

  6. Candidate PET radioligands for cannabinoid CB{sub 1} receptors: [{sup 18}F]AM5144 and related pyrazole compounds

    Energy Technology Data Exchange (ETDEWEB)

    Li Zizhong [Center for Translational Neuroimaging, Brookhaven National Laboratory, Upton, NY 11973 (United States); Gifford, Andrew [Center for Translational Neuroimaging, Brookhaven National Laboratory, Upton, NY 11973 (United States); Liu Qian [Center for Drug Discovery, Northeastern University, Boston, MA 02115 (United States); Thotapally, Rajesh [Center for Drug Discovery, Northeastern University, Boston, MA 02115 (United States); Ding Yushin [Center for Translational Neuroimaging, Brookhaven National Laboratory, Upton, NY 11973 (United States); Makriyannis, Alexandros [Center for Drug Discovery, Northeastern University, Boston, MA 02115 (United States); Gatley, S. John [Center for Translational Neuroimaging, Brookhaven National Laboratory, Upton, NY 11973 (United States) and Center for Drug Discovery, Northeastern University, Boston, MA 02115 (United States)]. E-mail: s.gatley@neu.edu

    2005-05-01

    Introduction: The mammalian brain contains abundant G protein-coupled cannabinoid CB{sub 1} receptors that respond to {delta}{sup 9}-tetrahydrocannabinol, the active ingredient of cannabis. The availability of a positron emission tomography (PET) radioligand would facilitate studies of the addictive and medicinal properties of compounds that bind to this receptor. Among the known classes of ligands for CB{sub 1} receptors, the pyrazoles are attractive targets for radiopharmaceutical development because they are antagonists and are generally less lipophilic than the other classes. Methods: A convenient high-yield synthesis of N-(4-[{sup 18}F]fluorophenyl)-5-(4-bromophenyl)-1-(2,4-dichlorophenyl)- 1H-pyrazole-3-carboxamide (AM5144) was devised by coupling the appropriate pyrazole-3-carboxyl chloride compound with 4-[{sup 18}F]fluoroaniline. The labeled precursor was synthesized from 1-[{sup 18}F]fluoro-4-nitrobenzene in 60% radiochemical yield for 10 min using an improved procedure involving sodium borohydride reduction with cobalt chloride catalysis. The product was purified by HPLC to give a specific activity >400 mCi/{mu}mol and a radiochemical purity >95%, and a PET study was conducted in a baboon. Results: Although the regional uptake of AM5144 in baboon brain was consistent with binding to cannabinoid CB{sub 1} receptors, absolute uptake at <0.003% injected radioactivity per cubic centimeter was lower than the previously reported uptake of the radioiodinated pyrazole AM281. Conclusions: The relatively poor brain uptake of AM5144 and other pyrazole CB{sub 1} receptor ligands is not surprising because of their high lipophilicity as compared with most brain PET radiotracers. However, for nine pyrazole compounds for which rodent data are available, brain uptake and calculated logP values are not correlated. Thus, high logP values should not preclude evaluation of radiotracers for targets such as the CB{sub 1} receptor that may require very lipophilic ligands.

  7. Surface modification and characterization of polycarbonate microdevices for capture of circulating biomarkers, both in vitro and in vivo.

    Science.gov (United States)

    Yeow, Bernard; Coffey, Jacob W; Muller, David A; Grøndahl, Lisbeth; Kendall, Mark A F; Corrie, Simon R

    2013-11-01

    Herein, we report the fabrication, characterization, and testing of a polymer microprojection array, for the direct and selective capture of circulating biomarkers from the skin of live mice. First, we modified polycarbonate wafers using an electrophilic aromatic substitution reaction with nitric acid to insert aromatic nitro-groups into the benzene rings, followed by treatment with sodium borohydride to reduce the nitro-groups to primary amines. Initial characterization by ultraviolet-visible (UV-vis) spectroscopy suggested that increasing acid concentration led to increased depth of material modification and that this was associated with decreased surface hardness and slight changes in surface roughness. Chemical analysis with X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance fourier transform infrared (ATR-FT-IR) spectroscopy showed nitrogen species present at the surface for all acid concentrations used, but subsurface nitrogen species were only observed at acid concentrations >35%. The nitrogen species were identified as a mixture of nitro, imine, and amine groups, and following reduction, there was sufficient amounts of primary amine groups for covalent attachment of a polyethylene glycol antifouling layer and protein capture probes, as determined by colorimetric and radiometric assays. Finally, the modification scheme was applied to polycarbonate microprojection arrays, and we show that these devices achieve flank skin penetration depths and biomarker yields comparable with our previously reported gold-coated silicon arrays, with very low nonspecific binding even in 10% mouse serum (in vitro) or directly in mouse skin (in vivo). This study is the first demonstration showing the potential utility of polymer microprojections in immunodiagnostics applications. PMID:24083844

  8. Hydrogen peroxide is a second messenger in phase 2 enzyme induction by cancer chemopreventive dithiolethiones.

    Science.gov (United States)

    Holland, Ryan; Navamal, Mettachit; Velayutham, Murugesan; Zweier, Jay L; Kensler, Thomas W; Fishbein, James C

    2009-08-01

    The ability of three dithiolethione cancer chemopreventives, oltipraz 1, anetholedithione (ADT) 2, 1,2-dithiole-3-thione (D3T) 3, and the major metabolite, 4, of 1, to induce the cytoprotective enzyme NQO1 in Hepa 1c1c7 cells and the inhibition of this induction by catalase are demonstrated. The ability of 1, 3, and 4 to form O(2)(*) has been reported, and it is here demonstrated that 2 decomposes in the presence of GSH to form, upon addition of the nitrone spin trap DMPO, the DMPO-OH adduct that is detectable by EPR. Decomposition of 2 in the presence of GSH elicits, upon the addition of hydroethidine and excitation at 510 nm, fluorescence at 580 nm that is diminished by the addition of superoxide dismutase. The compound 4, is a product of the reduction of 1, and it is demonstrated that 2 and 3 decompose in the presence of reductants such as thiolates and NaBH(4), followed by addition of CH(3)I, to form the dimethylated products of reductive cleavage of the S(1)-S(2) bond. The same products are isolated subsequent to lysis in buffer containing CH(3)I of Hepa 1c1c7 cells treated with 2 or 3. Reductive cleavage of 2 and 3 in aqueous ethanol by NaBH(4) in an argon atmosphere, followed by acidic destruction of remaining borohydride and neutralization and introduction of O(2) results in the reformation of 2 and 3 to the extent of 80 and 33%, respectively. The data in toto are consistent with a model in which dithiolethiones, generally, undergo reductive cleavage in Hepa 1c1c7 cells, thereby resulting in the generation of O(2)(*) that dismutates to H(2)O(2), that subsequently, by direct or indirect means, effects the nuclear translocation of transcription factor Nrf2, that upregulates phase 2 enzyme expression.

  9. Development of solvent-free ambient mass spectrometry for green chemistry applications.

    Science.gov (United States)

    Liu, Pengyuan; Forni, Amanda; Chen, Hao

    2014-04-15

    Green chemistry minimizes chemical process hazards in many ways, including eliminating traditional solvents or using alternative recyclable solvents such as ionic liquids. This concept is now adopted in this study for monitoring solvent-free reactions and analysis of ionic liquids, solids, and catalysts by mass spectrometry (MS), without using any solvent. In our approach, probe electrospray ionization (PESI), an ambient ionization method, was employed for this purpose. Neat viscous room-temperature ionic liquids (RTILs) in trace amounts (e.g., 25 nL) could be directly analyzed without sample carryover effect, thereby enabling high-throughput analysis. With the probe being heated, it can also ionize ionic solid compounds such as organometallic complexes as well as a variety of neat neutral solid chemicals (e.g., amines). More importantly, moisture-sensitive samples (e.g., [bmim][AlCl4]) can be successfully ionized. Furthermore, detection of organometallic catalysts (including air-sensitive [Rh-MeDuPHOS][OTf]) in ionic liquids, a traditionally challenging task due to strong ion suppression effect from ionic liquids, can be enabled using PESI. In addition, PESI can be an ideal approach for monitoring solvent-free reactions. Using PESI-MS, we successfully examined the alkylation of amines by alcohols, the conversion of pyrylium into pyridinium, and the condensation of aldehydes with indoles as well as air- and moisture-sensitive reactions such as the oxidation of ferrocene and the condensation of pyrazoles with borohydride. Interestingly, besides the expected reaction products, the reaction intermediates such as the monopyrazolylborate ion were also observed, providing insightful information for reaction mechanisms. We believe that the presented solvent-free PESI-MS method would impact the green chemistry field. PMID:24670064

  10. Utilizing metal tolerance potential of soil fungus for efficient synthesis of gold nanoparticles with superior catalytic activity for degradation of rhodamine B.

    Science.gov (United States)

    Bhargava, Arpit; Jain, Navin; Khan, Mohd Azeem; Pareek, Vikram; Dilip, R Venkataramana; Panwar, Jitendra

    2016-12-01

    In recent years, the surging demand of nanomaterials has boosted unprecedented expansion of research for the development of high yielding and sustainable synthesis methods which can deliver nanomaterials with desired characteristics. Unlike the well-established physico-chemical methods which have various limitations, biological methods inspired by mimicking natural biomineralization processes have great potential for nanoparticle synthesis. An eco-friendly and sustainable biological method that deliver particles with well-defined shape, size and compositions can be developed by selecting a proficient organism followed by fine tuning of various process parameter. The present study revealed high metal tolerance ability of a soil fungus Cladosporium oxysporum AJP03 and its potential for extracellular synthesis of gold nanoparticles. The morphology, composition and crystallinity of nanoparticles were confirmed using standard techniques. The synthesized particles were quasi-spherical in shape with fcc packing and an average particle size of 72.32 ± 21.80 nm. A series of experiments were conducted to study the effect of different process parameters on particle size and yield. Biomass: water ratio of 1:5 and 1 mM precursor salt concentration at physiological pH (7.0) favoured the synthesis of well-defined gold nanoparticles with maximum yield. The as-synthesized nanoparticles showed excellent catalytic efficiency towards sodium borohydride mediated reduction of rhodamine B (2.5 × 10(-5) M) within 7 min of reaction time under experimental conditions. Presence of proteins as capping material on the nanoparticle surface was found to be responsible for this remarkable catalytic efficiency. The present approach can be extrapolated to develop controlled and up-scalable process for mycosynthesis of nanoparticles for diverse applications. PMID:27567934

  11. Characterization of the synthesis of N,N-dimethyltryptamine by reductive amination using gas chromatography ion trap mass spectrometry.

    Science.gov (United States)

    Brandt, Simon D; Moore, Sharon A; Freeman, Sally; Kanu, Abu B

    2010-07-01

    The present study established an impurity profile of a synthetic route to the hallucinogenic N,N-dimethyltryptamine (DMT). The synthesis was carried out under reductive amination conditions between tryptamine and aqueous formaldehyde in the presence of acetic acid followed by reduction with sodium cyanoborohydride. Analytical characterization of this synthetic route was carried out by gas chromatography ion trap mass spectrometry using electron- and chemical-ionization modes. Methanol was employed as a liquid CI reagent and the impact of stoichiometric modifications on side-products formation was also investigated. Tryptamine 1, DMT 2, 2-methyltetrahydro-β-carboline (2-Me-THBC, 3), N-methyl-N-cyanomethyltryptamine (MCMT, 4), N-methyltryptamine (NMT, 5), 2-cyanomethyl-tetrahydro-β-carboline (2-CM-THBC, 6) and tetrahydro-β-carboline (THBC, 7) have been detected under a variety of conditions. Replacement of formaldehyde solution with paraformaldehyde resulted in incomplete conversion of the starting material whereas a similar replacement of sodium cyanoborohydride with sodium borohydride almost exclusively produced THBC instead of the expected DMT. Compounds 1 to 7 were quantified and the limits of detection were 28.4, 87.7, 21.5, 23.4, 41.1, 36.6, and 34.9 ng mL(-1), respectively. The limits of quantification for compounds 1 to 7 were 32.4, 88.3, 25.4, 24.6, 41.4, 39.9, and 37.0 µg mL(-1), respectively. Linearity was observed in the range of 20.8-980 µg mL(-1) with correlation coefficients > 0.99. The application holds great promise in the area of forensic chemistry where development of reliable analytical methods for the detection, identification, and quantification of DMT are crucial and also in pharmaceutical analysis where DMT might be prepared for use in human clinical studies. PMID:20648523

  12. Isolation of a very high molecular weight polylactosamine from an ovarian cyst mucin of blood group

    International Nuclear Information System (INIS)

    Treatment of a blood group A active ovarian cyst mucin glycoprotein with alkaline borohydride under conditions expected to cleave-O-glycosidically linked carbohydrate chains releases a polysaccharide of average molecular weight 25,000 daltons. It contains no peptide or mannose at the 1% level and carbohydrate analysis gives fuc:galNAc:gal:glcNAc in the ratio of 1:1:2.5:2.5. The 13C and 1H NMR spectra show that the polysaccharide has non-reducing terminal side chains of the structure galNAc(α-1 → 3)[fuc(α-1 → 2)] gal(β-1 → 3) glcNAc (i.e. a type 1 chain). Periodate oxidation removes all the fucose and galNAc from the non-reducing terminal but leaves intact the backbone composed of β-linked gal and glcNAc as would be expected for a polylactosamine. They conclude that this is a high molecular weight polylactosamine which is related to the asparagine linked polylactosamine chains of cell surface glycoproteins which have been implicated in cell differentiation. However, the blood group A polysaccharide from the ovarian cyst mucin is unique in several respects. It has a much larger molecular weight than even the erythroglycan of the red cell membrane protein, band 3, and is linked to the protein by an -O-glycosidic bond rather than the -N-asparagine linkage of the previously known polylactosamines which have a trimannosyl core. Its blood group A side chains are on a type one core rather than type 2 which is found on other polylactosamines

  13. Structural and metabolic studies of O-linked fucose-containing proteins of normal and virally-transformed rat fibroblasts

    International Nuclear Information System (INIS)

    Previous studies in this laboratory have demonstrated that cultured human and rodent cells contain a series of low molecular weight glycosylated amino acids of unusual structure, designated amino acid fucosides. The incorporation of radiolabelled-fucose into one of these components, designated FL4a (glucosylfucosylthreonine), is markedly-reduced in transformed epithelial and fibroblastic cells. The authors have examined fucose-labelled normal and virally-transformed rat fibroblast cell lines for glycoproteins which might be precursors to amino acid fucosides. Using milk alkaline/borohydride treatment (the beta-elimination reaction) to release O-linked oligosaccharides from proteins, they have isolated and partially characterized two low M/sub r/ reaction products (designated DS-ol and TS-ol) released from macromolecular cell material. The identity of one of these components (DS-ol, glucosylfucitol) suggested the existence in these cells of a direct protein precursor to FL4a. They examined fucose-labelled macromolecular cell material for proteins which release DS-ol (DS-proteins.). Using gel filtration chromatography and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) with subsequent autoradiography, they have observed DS-proteins which appear to exhibit a broad molecular weight size range, and are also present in culture medium from normal and transformed cells. The findings suggest that mammalian cells contain DS-proteins and TS-proteins with a novel carbohydrate-peptide linkage wherein L-fucose is O-linked to a polypeptide backbone. Metabolic studies were undertaken to examine both the relationship between DS-protein and FL4a and the biochemical basis for the decreased level of FL4a and the biochemical basis for the decreased level of FL4a observed in transformed cells

  14. Radiochemical synthesis of {sup 105g}Ag-labelled silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ichedef, C., E-mail: cigdem_ch@yahoo.com; Simonelli, F.; Holzwarth, U. [Institute for Health and Consumer Protection, European Commission, Joint Research Centre (Italy); Bagaria, J. Piella; Puntes, V. F. [Institut Català de Nanotecnologia (ICN2) (Spain); Cotogno, G.; Gilliland, D.; Gibson, N. [Institute for Health and Consumer Protection, European Commission, Joint Research Centre (Italy)

    2013-11-15

    A method for synthesis of radiolabelled silver nanoparticles is reported. The method is based on proton activation of silver metal powder, enriched in {sup 107}Ag, with a 30.7 MeV proton beam. At this proton energy {sup 105g}Ag is efficiently created, mainly via the {sup 107}Ag(p,3n){sup 105}Cd → {sup 105g}Ag reaction. {sup 105g}Ag has a half-life of 41.29 days and emits easily detectable gamma radiation on decay to {sup 105}Pd. This makes it very useful as a tracing radionuclide for experiments over several weeks or months. Following activation and a period to allow short-lived radionuclides to decay, the powder was dissolved in concentrated nitric acid in order to form silver nitrate (AgNO{sub 3}), which was used to synthesise radiolabelled silver nanoparticles via the process of sodium borohydride reduction. For comparison, non-radioactive silver nanoparticles were synthesised using commercially supplied AgNO{sub 3} in order to check if the use of irradiated Ag powder as a starting material would alter in any way the final nanoparticle characteristics. Both nanoparticle types were characterised using dynamic light scattering, zeta-potential and X-ray diffraction measurements, while additionally the non-radioactive samples were analysed by transmission electron microscopy and UV–Vis spectrometry. A hydrodynamic diameter of about 16 nm was determined for both radiolabelled and non-radioactive nanoparticles, while the electron microscopy on the non-radioactive samples indicated that the physical size of the metal NPs was (7.3 ± 1.4) nm.

  15. 微波消解-双道原子荧光光度计测定沙棘汁、沙棘果粉中的铅、砷、汞%Microwave Digestion-Double Line AFS Determination of Trace Lead, Arsenic and Mercury in Sea-buckthorn Juice and Sea-buckthorn-fruit-powder

    Institute of Scientific and Technical Information of China (English)

    汪正花; 段金凤; 师存杰

    2013-01-01

    Trace lead, arsenic and mercury in sea-buckthorn juice and sea-buckthorn-fruit-powder were determined by using microwave digestion-double lines AFS. The working conditions of instrument were discussed as well as influential factors including the sample digestion condition, potassium borohydride dosage, concentration and kinds of acids. The results show that detection limit of the method for each element is 0.000 1, 0.000 2, 0.000 02 mg/kg, respectively;The RSD is in the range of 1.20%~4.83%and the recoveries are in the range of 92%~105%.%采用微波消解技术-双道原子荧光法测定了沙棘汁、沙棘果粉中的痕量元素铅、砷、汞。对仪器的工作条件作了详述,还就各种对测定有影响的因素,包括样品消解条件,硼氢化钾的浓度、介质的种类及浓度等也作了研究并予以优化选择。方法对这3种元素的检出限为0.0001,0.0002,0.00002 mg/kg,相对标准偏差为1.2%~4.83%,用加标回收率评价方法的准确性,回收率为92%~105%。

  16. Morpholino spin-labeling for base-pair sequencing of a 3'-terminal RNA stem by proton homonuclear Overhauser enhancements: yeast ribosomal 5S RNA

    International Nuclear Information System (INIS)

    Base-pair sequences for 5S and 5.8S RNAs are not readily extracted from proton homonuclear nuclear Overhauser enhancement (NOE) connectivity experiments alone, due to extensive peak overlap in the downfield (11-15 ppm) proton NMR spectrum. In this paper, we introduce a new method for base-pair proton peak assignment for ribosomal RNAs, based upon the distance-dependent broadening of the resonances of base-pair protons spatially proximal to a paramagnetic group. Introduction of a nitroxide spin-label covalently attached to the 3'-terminal ribose provides an unequivocal starting point for base-pair hydrogen-bond proton NMR assignment. Subsequent NOE connectivities then establish the base-pair sequence for the terminal stem of a 5S RNA. Periodate oxidation of yeast 5S RNA, followed by reaction with 4-amino-2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO-NH2) and sodium borohydride reduction, produces yeast 5S RNA specifically labeled with a paramagnetic nitroxide group at the 3'-terminal ribose. Comparison of the 500-MHz 1H NMR spectra of native and 3'-terminal spin-labeled yeast 5S RNA serves to identify the terminal base pair (G1 . C120) and its adjacent base pair (G2 . U119) on the basis of their proximity to the 3'-terminal spin-label. From that starting point, we have then identified (G . C, A . U, or G . U) and sequenced eight of the nine base pairs in the terminal helix via primary and secondary NOE's

  17. Synthesis and characterization of NiFe{sub 2}O{sub 4}–Pd magnetically recyclable catalyst for hydrogenation reaction

    Energy Technology Data Exchange (ETDEWEB)

    Karaoğlu, E., E-mail: ekaraoglu@fatih.edu.tr [Department of Chemistry, Faculty of Arts and Sciences, Fatih University, 34500 B. Cekmece, Istanbul (Turkey); Özel, U.; Caner, C.; Baykal, A.; Summak, M.M. [Department of Chemistry, Faculty of Arts and Sciences, Fatih University, 34500 B. Cekmece, Istanbul (Turkey); Sözeri, H. [TUBITAK-UME, National Metrology Institute, PO Box 54, 41470 Gebze-Kocaeli (Turkey)

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► Novel superparamagnetic NiFe{sub 2}O{sub 4}–Pd magnetically recyclable catalyst was fabricated through co-precipitation. ► It could be reused several times without significant loss in catalytic activity for hydrogenation reaction. ► No further modification of the NiFe{sub 2}O{sub 4}–Pd magnetically recyclable catalyst is necessary for utilization as catalyst. -- Abstract: Herein we report the fabrication and characterization magnetically recyclable catalysts of NiFe{sub 2}O{sub 4}–Pd nanocomposite as highly effective catalysts for reduction reactions in liquid phase. The reduction Pd{sup 2+} was accomplished with polyethylene glycol 400 (PEG-400) instead of sodium borohydride (NaBH{sub 4}) and NiFe{sub 2}O{sub 4} nanoparticles was prepared by sonochemically using FeCI{sub 3}·6H{sub 2}O and NiCl{sub 2}. The chemical characterization of the product was done with X-ray diffractometry, Infrared spectroscopy, transmission electron microscopy, UV–Vis spectroscopy, thermal gravimetry and inductively coupled plasma. Thus formed NiFe{sub 2}O{sub 4}–Pd MRCs showed a very high activity in reduction reactions of 4-nitro aniline and 1,3-dinitrobenzene in liquid phase. It was found out that the catalytic activity of NiFe{sub 2}O{sub 4}–Pd MRCs on the reduction of 4-nitro aniline and 1,3-dinitrobenzene in liquid phase are between 99–93% and 98–93%, respectively. Magnetic character of this system allowed recovery and multiple use without significant loss of its catalytic activity. It is found that NiFe{sub 2}O{sub 4}–Pd MRCs showed very efficient catalytic activity and multiple usability.

  18. Design and fabrication of miniaturized PEM fuel cell combined microreactor with self-regulated hydrogen mechanism

    Science.gov (United States)

    Balakrishnan, A.; Frei, M.; Kerzenmacher, S.; Reinecke, H.; Mueller, C.

    2015-12-01

    In this work we present the design and fabrication of the miniaturized PEM fuel cell combined microreactor system with hydrogen regulation mechanism and testing of prototype microreactor. The system consists of two components (i) fuel cell component and (ii) microreactor component. The fuel cell component represents the miniaturized PEM fuel cell system (combination of screen printed fuel cell assembly and an on-board hydrogen storage medium). Hydrogen production based on catalytic hydrolysis of chemical hydride takes place in the microreactor component. The self-regulated hydrogen mechanism based on the gaseous hydrogen produced from the catalytic hydrolysis of sodium borohydride (NaBH4) gets accumulated as bubbles at the vicinity of the hydrophobic coated hydrogen exhaust holes. When the built up hydrogen bubbles pressure exceeds the burst pressure at the hydrogen exhaust holes the bubble collapses. This collapse causes a surge of fresh NaBH4 solution onto the catalyst surface leading to the removal of the reaction by-products formed at the active sites of the catalyst. The catalyst used in the system is platinum deposited on a base substrate. Nickel foam, carbon porous medium (CPM) and ceramic plate were selected as candidates for base substrate for developing a robust catalyst surface. For the first time the platinum layer fabricated by pulsed electrodeposition and dealloying (EPDD) technique is used for hydrolysis of NaBH4. The major advantages of such platinum catalyst layers are its high surface area and their mechanical stability. Prototype microreactor system with self-regulated hydrogen mechanism is demonstrated.

  19. Trans-α-xylosidase, a widespread enzyme activity in plants, introduces (1→4)-α-d-xylobiose side-chains into xyloglucan structures.

    Science.gov (United States)

    Franková, Lenka; Fry, Stephen C

    2012-06-01

    Angiosperms possess a retaining trans-α-xylosidase activity that catalyses the inter-molecular transfer of xylose residues between xyloglucan structures. To identify the linkage of the newly transferred α-xylose residue, we used [Xyl-(3)H]XXXG (xyloglucan heptasaccharide) as donor substrate and reductively-aminated xyloglucan oligosaccharides (XGO-NH(2)) as acceptor. Asparagus officinalis enzyme extracts generated cationic radioactive products ([(3)H]Xyl·XGO-NH(2)) that were Driselase-digestible to a neutral trisaccharide containing an α-[(3)H]xylose residue. After borohydride reduction, the trimer exhibited high molybdate-affinity, indicating xylobiosyl-(1→6)-glucitol rather than a di-xylosylated glucitol. Thus the trans-α-xylosidase had grafted an additional α-[(3)H]xylose residue onto the xylose of an isoprimeverose unit. The trisaccharide was rapidly acetolysed to an α-[(3)H]xylobiose, confirming the presence of an acetolysis-labile (1→6)-bond. The α-[(3)H]xylobiitol formed by reduction of this α-[(3)H]xylobiose had low molybdate-affinity, indicating a (1→2) or (1→4) linkage. In NaOH, the α-[(3)H]xylobiose underwent alkaline peeling at the moderate rate characteristic of a (1→4)-disaccharide. Finally, we synthesised eight non-radioactive xylobioses [α and β; (1↔1), (1→2), (1→3) and (1→4)] and found that the [(3)H]xylobiose co-chromatographed only with (1→4)-α-xylobiose. We conclude that Asparagus trans-α-xylosidase activity generates a novel xyloglucan building block, α-d-Xylp-(1→4)-α-d-Xylp-(1→6)-d-Glc (abbreviation: 'V'). Modifying xyloglucan structures in this way may alter oligosaccharin activities, or change their suitability as acceptor substrates for xyloglucan endotransglucosylase (XET) activity. PMID:22425285

  20. Tissue structure-specific distribution of glycosaminoglycans in the human penis.

    Science.gov (United States)

    Goulas, A; Papakonstantinou, E; Karakiulakis, G; Mirtsou-Fidani, V; Kalinderis, A; Hatzichristou, D G

    2000-09-01

    The aim of this work was to isolate and characterise the glycosaminoglycans present in the different tissue structures of the human penis in view of their potentially significant role in the physiology of erection. Penile tissue samples were obtained from patients who underwent penectomy and were subsequently dissected into individual tissue structures. Total glycosaminoglycans were isolated and purified from tunica albuginea, corpora cavernosa and corpus spongiosum, following tissue mincing, ultrasonication, lipid extraction, extensive digestion with pronase and DNase, treatment with alkali-borohydride and ethanol precipitation. Isolated glycosaminoglycans were separated by cellulose acetate electrophoresis and fractionated by anion exchange chromatography on DEAE Sephacel columns. Different glycosaminoglycan fractions were identified using glycosaminoglycan-degrading enzymes of known specificity. Gradient polyacrylamide gel electrophoresis was used to determine the average molecular mass of the glycosaminoglycans. The corpus cavernosum and the corpus spongiosum extracts contained almost twice the amount of glycosaminoglycan-associated uronic acids as compared to the tunical extracts (1.47+/-0.09, and 1.49+/-0.15 as opposed to 0.75+/-0.15 microg/mg dry defatted tissue, respectively; S.E.M., n=5). With the exception of hyaluronic acid, the relative amount of individual glycosaminoglycan types varied significantly among extracts of different origin. Heparan sulphate was more abundant in cavernosal, dermatan sulphate in tunical, and chondroitin-6-sulphate in corpus spongiosum extracts. No structure-specific differences were detected with respect to the molecular mass distribution of each glycosaminoglycan type. Our study shows that the different structures of the human penis produce distinct profiles of glycosaminoglycans, which are well suited to the individual functional characteristics of these structures. PMID:11084377

  1. Gum arabic modified Fe3O4 nanoparticles cross linked with collagen for isolation of bacteria

    Directory of Open Access Journals (Sweden)

    Chittor Raghuraman

    2010-12-01

    Full Text Available Abstract Background Multifunctional magnetic nanoparticles are important class of materials in the field of nanobiotechnology, as it is an emerging area of research for material science and molecular biology researchers. One of the various methods to obtain multifunctional nanomaterials, molecular functionalization by attaching organic functional groups to nanomagnetic materials is an important technique. Recently, functionalized magnetic nanoparticles have been demonstrated to be useful in isolation/detection of dangerous pathogens (bacteria/viruses for human life. Iron (Fe based material especially FePt is used in the isolation of ultralow concentrations (2 cfu/ml of bacteria in less time and it has been demonstrated that van-FePt may be used as an alternative fast detection technique with respect to conventional polymerase chain reaction (PCR method. However, still further improved demonstrations are necessary with interest to biocompatibility and green chemistry. Herein, we report the synthesis of Fe3O4 nanoparticles by template medication and its application for the detection/isolation of S. aureus bacteria. Results The reduction of anhydrous Iron chloride (FeCl3 in presence of sodium borohydride and water soluble polyelectrolyte (polydiallyldimethyl ammonium chloride, PDADMAC produces black precipitates. The X-ray diffraction (XRD, XPS and TEM analysis of the precipitates dried at 373 K demonstrated the formation of nanocrystalline Fe3O4. Moreover, scanning electron microscopy (SEM showed isolated staphylococcous aureus (S. aureus bacteria at ultralow concentrations using collagen coated gum arabic modified iron oxide nanoparticles (CCGAMION. Conclusion We are able to synthesize nanocrystalline Fe3O4 and CCGAMION was able to isolate S. aureus bacteria at 8-10 cfu (colony forming units/ml within ~3 minutes.

  2. Thematic outlook: the technical survey for the fuel cell research network PACO. April 16, 2004 update no. 23; Veille thematique. La veille technique pour le reseau PACO. Actualisation du 16 avril 2004, no. 23

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    Summaries of several recent articles are gathered here. They deal with fuel cells, means of transport, hydrogen production and storage. Their different titles are given below: 1)the importance of the fuel choice in the efficiency of the SOFC 2)assessment model of a centralized electric power system: SOFC/gas turbine 3)a direct borohydride fuel cell 4)thermodynamic optimization of the internal structure of a fuel cell 5)a SOFC/gas turbine cogeneration system 6)micro-fuel cells for portable applications 7)comparison of performances of direct alcohol fuel cells using different anode catalysts 8)materials and designs for SOFC used in stationary and mobile applications 9)development of measurement techniques for two-phase hydrogen weight flow 10)semi-conductors potentiometric probe for the hydrogen detection in air 11)integration of a fuel cell in an electric system, using a regulator based on the theory of regulation by disturbances accommodation 12)'greening London's black cabs': a study of the use potential of fuel cells cabs in London 13)gasification of leather residues - part 1 - experimental study in a pilot gasifier with a descending current 14)use of composite conducting membranes to produce hydrogen by water dissociation 15)molybdenum carbide based catalyst for the water gas reaction used in fuel cells vehicles applications 16)hydrogen production process from methane hydrates with carbon dioxide hydrates sequestration 17)comparative study between the hydrogen adsorption on super activated carbon and on carbon nano-tubes. The references of these articles are detailed. (O.M.)

  3. Characterization of electrochemically deposited films from aqueous and ionic liquid cobalt precursors toward hydrogen evolution reactions

    Science.gov (United States)

    Dushatinski, Thomas; Huff, Clay; Abdel-Fattah, Tarek M.

    2016-11-01

    Electrodepositions of cobalt films were achieved using an aqueous or an ethylene glycol based non-aqueous solution containing choline chloride (vitamin B4) with cobalt chloride hexahydrate precursor toward hydrogen evolution reactions from sodium borohydride (NaBH4) as solid hydrogen feedstock (SHF). The resulting cobalt films had reflectivity at 550 nm of 2.2% for aqueously deposited films (ACoF) and 1.3% for non-aqueously deposited films (NCoF). Surface morphology studied by scanning electron microscopy showed a positive correlation between particle size and thickness. The film thicknesses were tunable between >100 μm and <300 μm for each film. The roughness (Ra) value measurements by Dektak surface profiling showed that the NCoF (Ra = 165 nm) was smoother than the ACoF (Ra = 418 nm). The NCoFs and ACoFs contained only α phase (FCC) crystallites. The NCoFs were crystalline while the ACoFs were largely amorphous from X-ray diffraction analysis. The NCoF had an average Vickers hardness value of 84 MPa as compared to 176 MPa for ACoF. The aqueous precursor has a single absorption maximum at 510 nm and the non-aqueous precursor had three absorption maxima at 630, 670, and 695 nm. The hydrogen evolution reactions over a 1 cm2 catalytic surface with aqueous NaBH4 solutions generated rate constants (K) = equal to 4.9 × 10-3 min-1, 4.6 × 10-3 min-1, and 3.3 × 10-3 min-1 for ACoF, NCoF, and copper substrate respectively.

  4. Evaluating the performance of modified adsorbent of zero valent iron nanoparticles – Chitosan composite for arsenate removal from aqueous solutions

    Directory of Open Access Journals (Sweden)

    K Yaghmaeian

    2016-03-01

    Full Text Available Background and Objective: Arsenic is one of the most toxic pollutants in groundwater and surface water. Arsenic could have lots of adverse impacts on human health. Therefore, access to new technologies is required to achieve the arsenic standard. Materials and Methods: The present study was conducted at laboratory scale in non-continuous batches. The adsorbent of zero-valent iron nanoparticles -Chitosan was produced through reducing ferric iron by sodium borohydride (NaBH4 in the presence of chitosan as a stabilizer. At first, the effect of various parameters such as contact time (5-120 min, pH (3-10, adsorbent dose (0.3-3.5 g/L and initial concentration of arsenate (2-10 mg/L were investigated on process efficiency. Then optimum conditions in terms of contact time, pH, adsorbent dose and initial concentration of arsenate were determined by RSM method. Freundlich and Langmuir isotherm model equilibrium constant, pseudo-first and second order kinetic constants were calculated. The residual arsenate was measured y using ICP-AES. Results: The optimum values based on RSM for pH, absorbent dose, contact time, and initial concentration of arsenate were 7.16, 3.04 g/L, 91.48 min, and 9.71 mg/L respectively. Langmuir isotherm with R2= 0.9904 for Arsenate was the best graph for the experimental data. According to Langmuir isotherm model, the maximum amount of arsenate adsorption was 135.14mg/g. . The investigation of arsenate adsorption kinetics showed that arsenate adsorption follows the pseudo-second kinetics model. Conclusion: This research showed that the adsorption process is depended on pH. With increasing pH, the ability of amine groups in chitosan are decreased to protonation, caused to decrease the efficiency of arsenate removal at high pH.

  5. Fabrication of Bi-Fe{sub 3}O{sub 4}@RGO hybrids and their catalytic performance for the reduction of 4-nitrophenol

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xuefang; Xia, Fengling; Li, Xichuan; Xu, Xiaoyang; Wang, Huan; Yang, Nian; Gao, Jianping, E-mail: jianpinggaols@126.com [Tianjin University, School of Science (China)

    2015-11-15

    Nanocatalysts are frequently connected to magnetic nanoparticles. These composites are easy to be retrieved from the reaction system under a magnetic field because of their magnetic properties. Magnetic separation is particularly promising in industry since it can solve many issues present in filtration, centrifugation, or gravitation separation. Herein, a facile method to prepare bismuth and Fe{sub 3}O{sub 4} nanoparticles loaded on reduced graphene oxide magnetic hybrids (Bi-Fe{sub 3}O{sub 4}@RGO) using soluble starch as a dispersant is demonstrated. The magnetic Fe{sub 3}O{sub 4} nanoparticles were synthesized by the co-precipitation of Fe{sup 2+} and Fe{sup 3+} ions, and Bi nanoparticles were fabricated by the redox reactions between sodium borohydride and ammonium bismuth citrate in the presence of soluble starch. Transmission electron microscopy images demonstrate that the average diameter of the Fe{sub 3}O{sub 4} nanoparticles is about 5 nm and the diameters of Bi nanoparticles range from 10 to 20 nm. The magnetic Bi-Fe{sub 3}O{sub 4}@RGO hybrids exhibit high catalytic activity in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by NaBH{sub 4} with a first-order rate constant (K) of 0.00808 s{sup −1} and is magnetically recyclable for at least five cycles. This strategy provides an efficient and recyclable catalyst for the use in environmental protection applications.

  6. Sites in the diyne-ene bicyclic core of neocarzinostatin chromophore responsible for hydrogen abstraction from DNA

    International Nuclear Information System (INIS)

    The antitumor antibiotic neocarzinostatin exhibits its main drug action by abstracting hydrogen from DNA deoxyribose with consequent strand breakage or related lesions. All biological activities of the drug derive solely from a nonprotein chromophoric substance (NCS-chrom) consisting of a novel epoxy-bicyclo-diyne-ene system. Thiol or sodium borohydride activates NCS-chrom into a labile, reactive species that induces DNA damage but causes inactivation of the drug in the absence of the target DNA. Since three deuterium atoms can be incorporated into the drug by treatment with sodium borodeuteride without DNA, adding an unlabeled DNA under parallel conditions permitted the ready identification of the activated NCS-chrom product that abstracted hydrogen from the DNA. Not only does the activated NCS-chrom product have the same structure as the inactivated drug without DNA, but two of the incorporated deuterium atoms have been substituted by hydrogen. With the aid of NMR spectrometry, the two replaced hydrogen atoms are found to be incorporated into the C-2 and C-6 positions of the bicyclo-diyne-ene ring of NCS-chrom and are derived neither from borodeuteride nor from the hydroxyl functions of the solvents. In accord with current proposals, the two hydrogens incorporated into the drug may come from closely opposed sites on the complementary strands of the DNA at which the drug is bound. These findings are consistent with a diradical mechanism in which carbon-centered radicals at C-2 and C-6 of the activated drug result in abstraction of hydrogen atoms either from the deoxyribose moiety of DNA or, in the absence of DNA, from some other source, but not from the hydrogen attached to the sulfur of thiols under the conditions described

  7. 不同还原程度氧化石墨烯-水性聚氨酯共混膜的性能研究%The performances of the blended membranes of graphene oxide with different reduction degrees and water-based polyurethane

    Institute of Scientific and Technical Information of China (English)

    王闪闪; 王全杰; 曲家乐

    2013-01-01

    采用超声得到氧化石墨烯分散液,利用柠檬酸钠、抗坏血酸、L-半胱氨酸及硼氢化钠4种还原剂对氧化石墨烯进行还原,并与水性聚氨酯共混改性,通过实验探究还原后氧化石墨烯/水性聚氨酯复合材料的力学性能、介电性能.结果表明,还原后共混膜的力学性能、介电性等较未还原共混膜都有不同程度的改善,对导电性影响尤为显著,最好的共混膜提高了近1150倍,充分体现了石墨烯良好的导电性.%Graphene oxide was prepared by ultrasonic dissection and reduced with four reductants,including sodium citrate,ascorbic acid,L-cysteine and sodium borohydride,then modified with the water-borne polyurethane.The mechanical property,electrical conductivity of GO/WPU composite materials obtained through the experiment were studied.The results showed that both the mechani cal property and electrical conductivity of reduced materials significantly improved in different degrees,especially the conductivity particularly was raised 1150 times,which reflected the good electrical conductivity of graphene fully from this test.

  8. Kinetic and Thermodynamics of Methylene Blue Adsorption onto Zero Valent Iron Supported on Mesoporous Silica

    Directory of Open Access Journals (Sweden)

    Atyaf Khalid Hameed

    2016-08-01

    Full Text Available Zero valent iron supported on mesoporous silicanano particles (NZVI/MSNs was prepared by the aqueous phase borohydride reduction methods. Prior to the reduction, mesoporous silica nanoparticles (MSNs were prepared through the activation of fumed silica with concentrated HCl by refluxing at 90 °C. FTIR, XRD, FESEM, EDX and BET were used to characterize theadsorbents prepared. BET surface areas of MSNs, NZVI, and NZVI/MSNs were 126, 41, and 72 m2/g for, respectively. The performance of NZVI/MSNs as adsorbent was examined by adsorption of methylene blue (MB, performed in series of batch experiments. In the kinetic studies, pseudo first order and pseudo second order kinetic models were examined. The pseudo second order equation provided the best fit with the experimental data. Thermodynamic studies indicated that the adsorption process is endothermic with ΔH° was 90.53 kJ/mol. Positive ΔS° (300 J/mol and negative ΔG° (-6.42 kJ/mol was recorded, indicating the spontaneous of the adsorption process and naturally favorable. Copyright © 2016 BCREC GROUP. All rights reserved Received: 5th March 2016; Revised: 18th March 2016; Accepted: 18th March 2016 How to Cite: Hameed, A.K., Dewayanto, N., Dongyun, D., Nordin, M.R., Mohd Hasbi Ab. Rahim, M.H.A. (2016. Kinetic and Thermodynamics of Methylene Blue Adsorption onto Zero Valent Iron Supported on Mesoporous Silica. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (2: 250-261 (doi:10.9767/bcrec.11.2.443.250-261 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.2.443.250-261

  9. Antifungal activity of gold nanoparticles prepared by solvothermal method

    International Nuclear Information System (INIS)

    Graphical abstract: Gold nanoparticles (7 and 15 nm) of very high surface area (329 and 269 m2/g) have been successfully synthesized through solvothermal method by using tin chloride and sodium borohydride as reducing agents. As-prepared gold nanoparticles shows very excellent antifungal activity against Candida isolates and activity increases with decrease in the particle size. Display Omitted Highlights: ► Effect of reducing agents on the morphology of gold nanoparticles. ► Highly uniform and monodisperse gold nanoparticles (7 nm). ► Highest surface area of gold nanoparticles (329 m2/g). ► Excellent antifungal activity of gold nanoparticles against Candida strains. -- Abstract: Gold nanoparticles have been successfully synthesized by solvothermal method using SnCl2 and NaBH4 as reducing agents. X-ray diffraction studies show highly crystalline and monophasic nature of the gold nanoparticles with face centred cubic structure. The transmission electron microscopic studies show the formation of nearly spherical gold nanoparticles of average size of 15 nm using SnCl2, however, NaBH4 produced highly uniform, monodispersed and spherical gold nanoparticles of average grain size of 7 nm. A high surface area of 329 m2/g for 7 nm and 269 m2/g for 15 nm gold nanoparticles was observed. UV–vis studies assert the excitations over the visible region due to transverse and longitudinal surface plasmon modes. The gold nanoparticles exhibit excellent size dependant antifungal activity and greater biocidal action against Candida isolates for 7 nm sized gold nanoparticles restricting the transmembrane H+ efflux of the Candida species than 15 nm sized gold nanoparticles.

  10. 磁性纳米粒子Fe3O4@Au和Fe3O4@Ag的制备及表征%Synthesis and Characterization of Magnetic Fe3O4@Au and Fe3O4 @Ag Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    庄严; 周群; 周全法

    2011-01-01

    利用化学共沉淀法将铁盐和亚铁盐溶液按一定比例混合制备磁性纳米Fe3O4,再用3-巯基丙基三甲氧基硅烷修饰磁性粒子,连接金、银纳米粒子制备了核壳结构的功能性微粒.通过X-射线粉末衍射(XRD)、透射电子显微镜(TEM)及紫外-可见光吸收光谱仪(UV - Vis)对粒子的结构与性质进行表征.结果表明:磁性Fe3O4纳米粒子属立方晶型,Fe3O4@Au和Fe3O4@Ag粒子包裹完全,形状趋近于球形,兼有磁性和金、银纳米粒子的特性,对硝基化合物具有良好的催化性能.%Magnetic nanoparticles of Fe3O4 were prepared by co - deposition. Fe3O4 and gold/silver nano-particles were conjoined with (3 - mercapto - propyl) trimethoxysilane, and then core - shell functional Fe3O4@ Au and Fe3O4@ Ag nanoparticles were prepared by multi - step reduction with sodiumcitrate. These particles were characterized by TEM, XRD, UV - Vis. The analysis results showed that the prepared Fe3O4 nanoparticles are cubic structure. Spherical Fe3O4@ Au and Fe3O4@ Ag nanoparticles have excellent catalytic activity for the reduction of nitrocompounds by borohydride.

  11. A facile synthetic route toward air-stable magnetic nanoalloys with Fe–Ni/Fe–Co core and iron oxide shell

    International Nuclear Information System (INIS)

    Air-stable bimetallic spherically shaped Fe–Ni and Fe–Co magnetic nanoparticles (MNPs), having an average size of 15 nm and core–shell structure, were synthesized by a simple wet chemical method under ambient conditions. For the first time, sodium borohydride reduction method, commonly applied for the syntheses of metal nanoparticles, was used for the preparation of well-defined Fe–Ni and Fe–Co nanoalloys, avoiding exploitation of any organic solvent. This approach allows a large scale production of nanoparticles specifically stabilized by an iron oxyhydroxide shell without a need of secondary functionalization. Transmission electron microscopy, X-ray powder diffraction, X-ray fluorescence, magnetization, and Mössbauer data demonstrate a core–shell nature of the as-synthesized nanoparticles. The nanoparticle core is of metallic origin and is inhomogeneous at the atomic level, consisting of iron-rich and iron-poor alloy phases. The composition of the shell is close to the ferrihydrite and its role lies in prevention of oxidation-induced degradation of nanoparticle properties. The core is ferromagnetic at and below room temperature, experiencing superparamagnetic relaxation effects due to a reduced size of nanoparticles, whereas the shell is completely superparamagnetic at 300 K and magnetically orders below ∼25 K. Both developed types of magnetic nanoalloys exhibit a strong magnetic response under applied magnetic fields with a high magnetization values achievable at relatively low applied magnetic fields. Beside this, the highly biocompatible chemical composition of the nanoparticle shell and ability of its chemical modification by substitution or addition of other ions or molecules further empower the application potential of these MNPs, especially in the field of biomedicine.

  12. Synthesis and melting behaviour of Bi, Sn and Sn–Bi nanostructured alloy

    Energy Technology Data Exchange (ETDEWEB)

    Frongia, F.; Pilloni, M.; Scano, A.; Ardu, A.; Cannas, C.; Musinu, A. [Università di Cagliari, Dipartimento di Scienze Chimiche e Geologiche and Cagliari Research Unit of the National Consortium of Materials Science and Technology (INSTM), Cittadella Universitaria di Monserrato, 09042 Monserrato, CA (Italy); Borzone, G.; Delsante, S. [Department of Chemistry and Industrial Chemistry, Genoa University and Genoa Research Unit of the National Consortium of Materials Science and Technology (INSTM), Via Dodecaneso 31, I-16146 Genoa (Italy); Novakovic, R. [National Research Council (CNR), Institute for Energetics and Interphases (IENI), Via De Marini 6, 16149 Genoa (Italy); Ennas, G., E-mail: ennas@unica.it [Università di Cagliari, Dipartimento di Scienze Chimiche e Geologiche and Cagliari Research Unit of the National Consortium of Materials Science and Technology (INSTM), Cittadella Universitaria di Monserrato, 09042 Monserrato, CA (Italy)

    2015-02-25

    Highlights: • Aqueous solution route is used to produce Bi, Sn and Bi–Sn nanoparticles. • HRTEM revealed core–shell and Janus type structures of Bi–Sn nanoparticles. • Melting temperature depression of Bi and Bi–Sn nanoparticles were measured by DSC. • DSC data on Bi melting temperature depression agrees with theoretical values. - Abstract: Lead-free solders based on Bi–Sn bimetallic nanoclusters with eutectic composition (Bi{sub 43}Sn{sub 57}) were synthesized at low temperature by simultaneous reduction reaction from aqueous solution containing bismuth and tin chlorides, using potassium borohydride as a reducing agent. By the same processing route, pure bismuth and tin nanoparticles have also been prepared. Microstructure, morphology and composition of the samples were characterized by X-ray powder diffraction (XRD), transmission (TEM) and scanning electron microscopy (SEM). TEM images of Bi–Sn nanoparticles show average size ranging from 30 to 100 nm. Thermal behaviour of Bi–Sn nanopowders was studied by DSC (differential scanning calorimetry) and a melting temperature (135 °C) lower than that of the corresponding microcrystalline sample (139 °C) was observed. SEM micrographs of the thermally treated sample up to 400 °C show fine spherical grains in the micrometer range with finer powder particles on the surface. XRD powder diffraction analysis indicates the formation of bismuth and tin nanophases with an average particle size of 85 and 126 nm, respectively. The oxidation behaviour of the samples was also investigated. The results obtained have been analyzed in view of theoretical models describing the melting temperature depression of nanoparticles.

  13. Enhanced dechlorination of m-DCB using iron@graphite/palladium (Fe@C/Pd) nanoparticles produced by pulsed laser ablation in liquid.

    Science.gov (United States)

    Yu, Yiseul; Jung, Hyeon Jin; Je, Mingyu; Choi, Hyun Chul; Choi, Myong Yong

    2016-07-01

    In this work, the zero valent Fe (ZVI) and graphite-encapsulated Fe (Fe@C) nanoparticles (NPs) were easily and selectively prepared by a pulsed laser ablation (PLA) method in an aqueous sodium borohydride solution and ascorbic acid dissolved in methanol, respectively. Here, the Fe@C NPs were uniquely synthesized by PLA in methanol, where the solvent is used as both a carbon source for the graphitic layers and solvent, which is very unique. Furthermore, Pd NPs were loaded onto the surface of the Fe@C NPs to prepare bimetallic (Fe@C/Pd) NPs for the enhancement of the degradation efficiency of m-dichlorobenzene (m-DCB). The morphology, crystallinity, and surface composition of the prepared NPs were carefully characterized by high-resolution transmission electron microscopy (HRTEM), energy dispersive x-ray spectrometer (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The degradation rate of m-DCB using single (Fe and Pd) or bimetallic (Fe/Pd and Fe@C/Pd) NPs were compared by using gas chromatography. Among these NPs produced in this work, the Fe@C/Pd NPs with 1.71 wt % of Pd showed an excellent dechlorination efficiency for m-DCB with 100% degradation within 75 min. The graphitic layer on the Fe NPs played as not only an oxidation resistant for the Fe NPs to surroundings, but also a supporter of the Pd NPs for the enhanced degradation efficiency of m-DCB. PMID:27129061

  14. Silver/poly (lactic acid nanocomposites: preparation, characterization, and antibacterial activity

    Directory of Open Access Journals (Sweden)

    Kamyar Shameli

    2010-08-01

    Full Text Available Kamyar Shameli1, Mansor Bin Ahmad1, Wan Md Zin Wan Yunus1, Nor Azowa Ibrahim1, Russly Abdul Rahman2, Maryam Jokar2,3, Majid Darroudi41Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, Selangor, Malaysia; 2Department of Food Technology, Faculty of Food Science and Technology, Universiti Putra Malaysia, Selangor, Malaysia; 3Department of Food Technology, Islamic Azad University, Damghan Branch, Damghan, Iran; 4Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology (ITMA, Universiti Putra Malaysia, Selangor, MalaysiaAbstract: In this study, antibacterial characteristic of silver/poly (lactic acid nanocomposite (Ag/PLA-NC films was investigated, while silver nanoparticles (Ag-NPs were synthesized into biodegradable PLA via chemical reduction method in diphase solvent. Silver nitrate and sodium borohydride were respectively used as a silver precursor and reducing agent in the PLA, which acted as a polymeric matrix and stabilizer. Meanwhile, the properties of Ag/PLA-NCs were studied as a function of the Ag-NP weight percentages (8, 16, and 32 wt% respectively, in relation to the use of PLA. The morphology of the Ag/PLA-NC films and the distribution of the Ag-NPs were also characterized. The silver ions released from the Ag/PLA-NC films and their antibacterial activities were scrutinized. The antibacterial activities of the Ag/PLA-NC films were examined against Gram-negative bacteria (Escherichia coli and Vibrio parahaemolyticus and Gram-positive bacteria (Staphylococcus aureus by diffusion method using Muller–Hinton agar. The results indicated that Ag/PLA-NC films possessed a strong antibacterial activity with the increase in the percentage of Ag-NPs in the PLA. Thus, Ag/PLA-NC films can be used as an antibacterial scaffold for tissue engineering and medical application.Keywords: antibacterial activity, silver nanoparticles, biodegradable, poly (lactic acid, Muller–Hinton agar.

  15. Highly stable, protein capped gold nanoparticles as effective drug delivery vehicles for amino-glycosidic antibiotics

    International Nuclear Information System (INIS)

    A method for the production of highly stable gold nanoparticles (Au NP) was optimized using sodium borohydride as reducing agent and bovine serum albumin as capping agent. The synthesized nanoparticles were characterized using UV–visible spectroscopy, transmission electron microscopy, X‐ray diffraction (XRD) and dynamic light scattering techniques. The formation of gold nanoparticles was confirmed from the appearance of pink colour and an absorption maximum at 532 nm. These protein capped nanoparticles exhibited excellent stability towards pH modification and electrolyte addition. The produced nanoparticles were found to be spherical in shape, nearly monodispersed and with an average particle size of 7.8 ± 1.7 nm. Crystalline nature of the nanoparticles in face centered cubic structure is confirmed from the selected‐area electron diffraction and XRD patterns. The nanoparticles were functionalized with various amino-glycosidic antibiotics for utilizing them as drug delivery vehicles. Using Fourier transform infrared spectroscopy, the possible functional groups of antibiotics bound to the nanoparticle surface have been examined. These drug loaded nanoparticle solutions were tested for their antibacterial activity against Gram-negative and Gram-positive bacterial strains, by well diffusion assay. The antibiotic conjugated Au NP exhibited enhanced antibacterial activity, compared to pure antibiotic at the same concentration. Being protein capped and highly stable, these gold nanoparticles can act as effective carriers for drugs and might have considerable applications in the field of infection prevention and therapeutics. - Highlights: ► Method for NaBH4 reduced and BSA capped gold nanoparticle was standardized. ► Nanoparticles were spherical and nearly monodispersed with a size of 7.8 nm. ► Nanoparticles are extremely stable towards pH modification and electrolyte addition. ► Antibiotic conjugated nanoparticles exhibited enhanced antibacterial activity

  16. Determination of arsenic by pervaporation-flow injection hydride generation and permanganate spectrophotometric detection

    Energy Technology Data Exchange (ETDEWEB)

    Rupasinghe, Thusitha; Cardwell, Terence J.; Cattrall, Robert W.; Potter, Ian D.; Kolev, Spas D

    2004-05-17

    A novel pervaporation-flow injection (PFI) system for the determination of As(III) in aqueous samples at {mu}g l{sup -1} level is described. The analytical procedure involved stopping the acceptor stream and injecting acidified As(III) samples into a 0.3 M HCl stream which was mixed with a 0.14 M sodium borohydride in 0.025 M NaOH stream. The arsine generated was transported in the pervaporation unit across a semi-permeable membrane (1.5 mm thickness) into the static acceptor solution containing 1.0x10{sup -4} M KMnO{sub 4} in 0.1 M H{sub 2}SO{sub 4} where it was oxidised. The acceptor stream was restarted after 6.5 min, and the decrease in permanganate absorbance at 528 nm was monitored to determine the initial concentration of As(III) in the samples. The method is characterised by a linear calibration range from 0.25 to 2000 {mu}g l{sup -1}, a detection limit of 0.18 {mu}g l{sup -1} and a sampling frequency of 7 h{sup -1}. Samples containing As(V) were pre-treated with KI and HCl prior to injection to reduce As(V) to As(III). The effects of common anionic and cationic interferences, and the elimination of some metallic interferences using L-cysteine are discussed. The method was applied to the analysis of environmental waters and the results were in good agreement with hydride generation atomic absorption spectrometric data.

  17. Synthesis and formation mechanism of Ag-Ni alloy nanoparticles at room temperature

    Science.gov (United States)

    Yan, Shi; Sun, Dongbai; Tan, Yuanyuan; Xing, Xueqing; Yu, Hongying; Wu, Zhonghua

    2016-11-01

    Ag-Ni nanoparticles were prepared with a chemical reduction method in the presence of polyvinylpyrrolidone (PVP) used as a stabilizing agent. During the synthesis of Ag-Ni nanoparticles, silver nitrate was used as the Ag+ source while nickel sulfate hexahydrate was used as Ni2+ source. Mixed solutions of Ag+ source and Ni2+ source were used as the precursors and sodium borohydride was used as the reducing agent. Five ratios of Ag+/Ni2+ (9:1, 3:1, 1:1, 1:3, and 1:9) suspensions were prepared in the corresponding precursors. Ag-Ni alloy nanoparticles were obtained with this method at room temperature. Scanning electronic microscope (SEM), energy dispersive spectrum (EDS), high resolution transmission electron microscope (HRTEM) were used to characterize the morphology, composition and crystal structure of the nanoparticles. The crystal structure was also investigated with X-ray diffraction (XRD). In all five Ag/Ni ratios, two kinds of particle structures were observed that are single crystal structure and five-fold twinned structure respectively. Free energy of nanoparticles with different crystal structures were calculated at each Ag/Ni ratio. Calculated results revealed that, with identical volume, free energy of single crystal particle is lower than multi-twinned particle and the difference becomes smaller with the increase of particle size; increase of Ni content will lead the increase of free energy for both structures. Formation of different crystal structures are decided by the structure of the original nuclei at the very early stage of the reduction process.

  18. Primary structure determination of five sialylated oligosaccharides derived from bronchial mucus glycoproteins of patients suffering from cystic fibrosis. The occurrence of the NeuAc alpha(2----3)Gal beta(1----4)[Fuc alpha(1----3)] GlcNAc beta(1----.) structural element revealed by 500-MHz 1H NMR spectroscopy.

    Science.gov (United States)

    Lamblin, G; Boersma, A; Klein, A; Roussel, P; van Halbeek, H; Vliegenthart, J F

    1984-07-25

    The structure of sialylated carbohydrate units of bronchial mucins obtained from cystic fibrosis patients was investigated by 500-MHz 1H NMR spectroscopy in conjunction with sugar analysis. After subjecting the mucins to alkaline borohydride degradation, sialylated oligosaccharide-alditols were isolated by anion-exchange chromatography and fractionated by high performance liquid chromatography. Five compounds could be obtained in a rather pure state; their structures were established as the following: A-1, NeuAc alpha(2----3)Gal beta(1----4) [Fuc alpha(1----3)]GlcNAc beta(1----3)Gal-NAc-ol; A-2, NeuAc alpha(2----3)Gal beta(1----4)GlcNAc beta(1----6)-[GlcNAc beta (1----3)]GalNAc-o1; A-3, NeuAc alpha(2----3)Gal beta-(1----4)[Fuc alpha(1----3)]GlcNAc beta(1----3)Gal beta(1----3) GalNAc-o1; A-4, NeuAc alpha(2----3)Gal beta(1----4)[Fuc alpha(1----3)]Glc-NAc NAc beta(1----6)[GlcNAc beta(1----3)]GalNAc-o1; A-6,NeuAc alpha-(2----3) Gal beta(1----4)[Fuc alpha(1----3)]GlcNAc beta(1----6)[Gal beta-(1----4) GlcNAc beta(1----3)]GalNAc-o1. The simultaneous presence of sialic acid in alpha(2----3)-linkage to Gal and fucose in alpha(1----3)-linkage to GlcNAc of the same N-acetyllactosamine unit could be adequately proved by high resolution 1H NMR spectroscopy. This sequence constitutes a novel structural element for mucins. PMID:6746638

  19. KDN-containing glycoprotein from loach skin mucus.

    Science.gov (United States)

    Nakagawa, H; Hama, Y; Sumi, T; Li, S C; Li, Y T

    2001-01-01

    It has been widely recognized that the mucus coat of fish plays a variety of important physical, chemical, and physiological functions. One of the major constituents of the mucus coat is mucus glycoprotein. We found that sialic acids in the skin mucus of the loach, Misgurnus anguillicaudatus, consisted predominantly of KDN. Subsequently, we isolated KDN-containing glycoprotein from loach skin mucus and characterized its chemical nature and structure. Loach mucus glycoprotein was purified from the Tris-HCl buffer extract of loach skin mucus by DEAE-cellulose chromatography, Nuclease P1 treatment, and Sepharose CL-6B gel filtration. The purified mucus glycoprotein was found to contain 38.5 KDN, 0.5% NeuAc, 25.0% GalNAc, 3.5% Gal, 0.5% GlcNAc and 28% amino acids. Exhaustive Actinase digestion of the glycoprotein yielded a glycopeptide with a higher sugar content and higher Thr and Ser contents. The molecular size of this glycopeptide was approximately 1/12 of the intact glycoprotein. These results suggest that approximately 11 highly glycosylated polypeptide units are linked in tandem through nonglycosylated peptides to form the glycoporotein molecule. The oligosaccharide alditols liberated from the loach mucus glycoprotein by alkaline borohydride treatment were separated by Sephadex G-25 gel filtration and HPLC. The purified sugar chains were analyzed b --> 6GalNAc-ol, KDNalpha2 --> 3(GalNAcbeta1 --> 14)GalNAc-ol, KDNalpha2 --> 6(GalNAcalpha1 --> 3)GalNAc-ol, KDNalpha2 --> 6(Gal3alpha1--> 3)GalNAc-ol, and NeuAcalpha2 --> 6Gal NAc-ol. It is estimated that one loach mucus glycoprotein molecule contains more than 500 KDN-containing sugar chains that are linked to Thr and Ser residues of the protein core through GalNAc. PMID:14533798

  20. A copper(I) homocubane collapses to a tetracapped tetrahedron upon hydride insertion.

    Science.gov (United States)

    Liao, Ping-Kuei; Liu, Kuan-Guan; Fang, Ching-Shiang; Liu, C W; Fackler, John P; Wu, Ying-Yann

    2011-09-01

    The hydrido copper(I) and silver(I) clusters incorporating 1,1-dicyanoethylene-2,2-dithiolate (i-MNT) ligands are presented in this paper. Reactions of M(I) (M = Cu, Ag) salts, [Bu(4)N](2)[S(2)CC(CN)(2)], with the anion sources ([Bu(4)N][BH(4)] for H(-), [Bu(4)N][BD(4)] for D(-)) in an 8:6:1 molar ratio in THF produce octanuclear penta-anionic Cu(I)/Ag(I) clusters, [Bu(4)N](5)[M(8)(X){S(2)CC(CN)(2)}(6)] (M = Cu, X = H, 1(H); X = D, 1(D); M = Ag, X = H, 2(H); X = D, 2(D)). They can also be produced from the stoichiometric reaction of M(8)(i-MNT)(6)(4-) with the ammonium borohydride. All four compounds have been fully characterized spectroscopically ((1)H and (13)C NMR, IR, UV-vis) and by elemental analyses. The deuteride-encapsulated Cu(8)/Ag(8) clusters of 1(D) and 2(D) are also characterized by (2)H NMR. X-ray crystal structures of 1(H) and 2(H) reveal a hydride-centered tetracapped tetrahedral Cu(8)/Ag(8) core, which is inscribed within an S(12) icosahedron formed by six i-MNT ligands, each in a tetrametallic-tetraconnective (μ(2), μ(2)) bonding mode. The encapsulated hydride in 2(H) is unequivocally characterized by both (1)H and (109)Ag NMR spectroscopies, and the results strongly suggest that the hydride is coupled to eight magnetically equivalent silver nuclei on the NMR time scale. Therefore, a fast interchange between the vertex and capping silver atoms in solution gives a plausible explanation for the perceived structural differences between the Ag(8) geometry deduced from the X-ray structure and the NMR spectra.

  1. Chemically stable and reusable nano zero-valent iron/graphite-like carbon nitride nanohybrid for efficient photocatalytic treatment of Cr(VI) and rhodamine B under visible light

    Science.gov (United States)

    Liang, Zhiyu; Wen, Qingjuan; Wang, Xiu; Zhang, Fuwei; Yu, Yan

    2016-11-01

    Graphite-like carbon nitride (g-C3N4) displays strong potential applications in visible-light photocatalytic for water treatment, but its applications are greatly restricted by high recombination probability of photo-generated electron-hole pairs, as well as a weak reduction ability toward the heavy metals. In this work, we reported the synthesis of nZVI-g-C3N4 nano-hybrid with highly efficiency toward the photodegradation of RhB and Cr(VI) under the visible light irradiation. The nZVI nanoparticles can well be immobilized and dispersed on the surface of g-C3N4 nanosheets by a facile borohydride-reduction method. As-synthesized nZVI-g-C3N4 has an improved photocatalytic activity much better than that of the pure g-C3N4, wherein over 92.9% of Cr(VI) and 99.9% of RhB can be removed by using nZVI-g-C3N4. The nZVI particles not only contributes to the reduction and immobilization of Cr(VI), but also accelerates the photocatalytic degradation efficiency of RhB due to a lower recombination rate of photoexcited holes and electrons. Moreover, nZVI-g-C3N4 preserves superior photodegradation efficiency after five experimental cycles. It can be attributed that nZVI-g-C3N4 photocatalyst is chemically stable, and part of nZVI can be recovered by g-C3N4. We believe that, the composite of nZVI-g-C3N4 reported here could provide guidance for the design of efficient and reusable materials to remove both the organic compounds and heavy metal ions from waste waters.

  2. Synthesis, characterization and catalytic activity of CoFe{sub 2}O{sub 4}-APTES-Pd magnetic recyclable catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Demirelli, M. [Department of Chemistry, Faculty of Arts and Sciences, Yıldız Teknik University Davutpaşa Campus, Esenler, İstanbul (Turkey); Department of Chemistry, Faculty of Arts and Sciences, Fatih University, B. Cekmece, İstanbul 34500 (Turkey); Karaoğlu, E., E-mail: ebubekirkaraoglu@gmail.com [Department of Chemistry, Faculty of Arts and Sciences, Fatih University, B. Cekmece, İstanbul 34500 (Turkey); Department of Medical Biochemistry, Faculty of Medicine, Sakarya University, Korucuk, Sakarya (Turkey); Baykal, A. [Department of Chemistry, Faculty of Arts and Sciences, Fatih University, B. Cekmece, İstanbul 34500 (Turkey); Sözeri, H.; Uysal, E. [TUBITAK-UME, National Metrology Institute, PO Box 54, 41470 Gebze, Kocaeli (Turkey)

    2014-01-05

    Highlights: • CoFe{sub 2}O{sub 4}-APTES-Pd (0) nanocomposite, as effective catalysts for reduction reactions. • It could be reused several times without significant loss in hydrogenation reaction. • So far, CoFe{sub 2}O{sub 4}-APTES-Pd (0) nanocomposite have not been synthesized. • CoFe{sub 2}O{sub 4}-APTES-Pd (0) nanocomposite was confirmed by XRD, FT-IR. • Pd containing nanoparticles embedded in organic surfactant observed by TEM. -- Abstract: A new magnetically recyclable catalyst, CoFe{sub 2}O{sub 4}-APTES-Pd(0) nanocomposite, as highly effective catalysts for reduction reactions in liquid phase was fabricated and characterized. The reduction of Pd{sup 2+} was accomplished with sodium borohydride (NaBH{sub 4}). The chemical characterization of the product was done with X-ray diffractometry, infrared spectroscopy, transmission electron microscopy, UV–Vis spectroscopy and inductively coupled plasma. It was found that the combination of CoFe{sub 2}O{sub 4} and 3-aminopropyltriethoxysilane (APTES) could give rise to structurally stable catalytic sites. Furthermore, the high magnetization CoFe{sub 2}O{sub 4}-APTES-Pd(0) catalyst can be recovered by magnet and reused for ten runs for hydrogenation reaction of 4-nitro aniline, 1,3 dinitro and cyclohexanone. The catalyst was easily isolated from the reaction mixture by a magnetic bar and reused at least 10 times without significant degradation in the activity which shows the indicative of a potential applications of these catalysts in industry.

  3. In situ synthesized gold nanoparticles in hydrogels for catalytic reduction of nitroaromatic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Xiao-Qiong; Wu, Xing-Wen; Huang, Qing [Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Shen, Jiang-Shan, E-mail: jsshen@iue.ac.cn [Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Ningbo Urban Environment Observation and Research Station, Chinese Academy of Sciences, Ningbo 315800 (China); Zhang, Hong-Wu, E-mail: hwzhang@iue.ac.cn [Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China)

    2015-03-15

    Graphical abstract: - Highlights: • In situ preparing Au nanoparticles by photoreduction in chitosan hydrogels was firstly achieved. • In situ photoreduction for creating Au nanoparticles is environmentally friendly and the operation procedure is very simple. • The as-prepared Au nanoparticles have good catalytic performance. • Affording an effective strategy for converting some high explosive compounds such as 2,4,6-tNT to nonexplosive. - Abstract: Developing hydrogel systems featured by catalytic active is of importance to construct highly effective platforms for removing environmental pollutants/hazardous substances or for bio-/chemosensing. Reported herein are our recent finding that Au nanoparticles could be in situ prepared in chitosan-Au{sup III} hydrogel system via photoreduction, and the as-prepared Au nanoparticles could be employed for the catalytic reduction of a series of nitroaromatic compounds by sodium borohydride (NaBH{sub 4}). Experimental conditions of synthesizing Au nanoparticles, including pH, concentration of Au{sup III}, and light irradiation time were systematically investigated. The as-prepared Au nanoparticles were characterized by UV–vis absorption spectroscopy, X-ray diffraction (XRD), transmission and field emission scanning electron microscopy (TEM and FESEM). This is the first example for in situ formed metal nanoparticles in chitosan hydrogel systems via photoreduction. The effectiveness of the as-prepared Au nanoparticles as nanocatalysts was evaluated by employing the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by NaBH{sub 4} as a model reaction. The catalytic reduction reaction was found to be very efficient and to follow a pseudo-first-order kinetics. The as-prepared Au nanoparticles demonstrated good reusability and stability. The reduction of a series of other nitroaromatic compounds including highly explosives 2,4,6-trinitrophenol (2,4,6-tNP) and 2,4,6-trinitrotoluene (2,4,6-tNT) was achieved by means

  4. Novel observations of dynamic crystallography in the solid-state LiBH4/MgH2 hydrogen absorption reaction

    International Nuclear Information System (INIS)

    The Lithium hydride/magnesium di-boride system has been the subject of much investigation due to its potential in solving the mobile hydrogen storage problem. While its weight (11.4 wt%) and volume densities of hydrogen are favourable, it has been found to react at unfavourable temperatures. Performance improvements have been made since through the use of additives and micro-/nano-structuring. In order to make neutron diffraction viable, magnesium di-boride was synthesised using 11 B enriched boron. This was then used as a constituent in the samples, which consisted primarily of a 2:1 molar ratio LiH to MgB2, some an additives 5 at% (VCI3). In-situ time-of-flight neutron diffraction was undertaken (Polaris, ISIS, United Kingdom) for both the forward and back reaction: 2LiH + MgB2 + 4H2 ↔ 2LiBH4 + MgH2. The absorption was performed at the temperature of 250°C so as to have the products of the reaction remain solid, and thus measurable using diffraction. The reaction was observed to progress, although not to completion due to time restrictions. A crystallographic change was observed in the formed lithium borohydride; a lattice parameter shifting as a function of hydrogen content within the sample. Attenuation correction was performed, applying the model that Gray et al proposed for masked TOF cells. For the actual application this model, assumptions and approximations were necessary in this instance.

  5. Polysialylated N-Glycans Identified in Human Serum Through Combined Developments in Sample Preparation, Separations and Electrospray ionization-mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Kronewitter, Scott R.; Marginean, Ioan; Cox, Jonathan T.; Zhao, Rui; Hagler, Clay D.; Shukla, Anil K.; Carlson, Timothy S.; Adkins, Joshua N.; Camp, David G.; Moore, Ronald J.; Rodland, Karin D.; Smith, Richard D.

    2014-09-02

    The N-glycan diversity of human serum glycoproteins, i.e. the human blood serum N-glycome, is complex due to the range of glycan structures potentially synthesizable by human glycosylation enzymes. The reported glycome, however, is limited by methods of sample preparation, available analytical platforms, e.g., based upon electrospray ionization-mass spectrometry (ESI-MS), and software tools for data analysis. In this report, several improvements have been implemented in sample preparation and analysis to extend ESI-MS glycan characterization and to provide an improved view of glycan diversity. Sample preparation improvements include acidified, microwave-accelerated, PNGase F N-glycan release, and sodium borohydride reduction were optimized to improve quantitative yields and conserve the number of glycoforms detected. Two-stage desalting (during solid phase extraction and on the analytical column) increased the sensitivity by reducing analyte signal division between multiple reducing-end-forms or cation adducts. On-line separations were improved by using extended length graphitized carbon columns and adding TFA as an acid modifier to a formic acid/reversed phase gradient which provides additional resolving power and significantly improved desorption of both large and heavily sialylated glycans. To improve MS sensitivity and provide gentler ionization conditions at the source-MS interface, subambient pressure ionization with nanoelectrospray (SPIN) has been utilized. When method improvements are combined together with the Glycomics Quintavariate Informed Quantification (GlyQ-IQ) recently described1 these technologies demonstrate the ability to significantly extend glycan detection sensitivity and provide expanded glycan coverage. We demonstrate application of these advances in the context of the human serum glycome, and for which our initial observations include detection of a new class of heavily sialylated N-glycans, including polysialylated N-glycans.

  6. Fine structure characterization of zero-valent iron nanoparticles for decontamination of nitrites and nitrates in wastewater and groundwater

    Directory of Open Access Journals (Sweden)

    Kuen-Song Lin et al

    2008-01-01

    Full Text Available The main objectives of the present study were to investigate the chemical reduction of nitrate or nitrite species by zero-valent iron nanoparticle (ZVIN in aqueous solution and related reaction kinetics or mechanisms using fine structure characterization. This work also exemplifies the utilization of field emission-scanning electron microscope (FE–SEM, transmission electron microscopy (TEM, and x-ray diffraction (XRD to reveal the speciation and possible reaction pathway in a very complex adsorption and redox reaction process. Experimentally, ZVIN of this study was prepared by sodium borohydride reduction method at room temperature and ambient pressure. The morphology of as-synthesized ZVIN shows that the nearly ball and ultrafine particles ranged of 20–50 nm were observed with FE–SEM or TEM analysis. The kinetic model of nitrites or nitrates reductive reaction by ZVIN is proposed as a pseudo first-order kinetic equation. The nitrite and nitrate removal efficiencies using ZVIN were found 65–83% and 51–68%, respectively, based on three different initial concentrations. Based on the XRD pattern analyses, it is found that the quantitative relationship between nitrite and Fe(III or Fe(II is similar to the one between nitrate and Fe(III in the ZVIN study. The possible reason is due to the faster nitrite reduction by ZVIN. In fact, the occurrence of the relative faster nitrite reductive reaction suggested that the passivation of the ZVIN have a significant contribution to iron corrosion. The extended x-ray absorption fine structure (EXAFS or x-ray absorption near edge structure (XANES spectra show that the nitrites or nitrates reduce to N2 or NH3 while oxidizing the ZVIN to Fe2O3 or Fe3O4 electrochemically. It is also very clear that decontamination of nitrate or nitrite species in groundwater via the in-situ remediation with a ZVIN permeable reactive barrier would be environmentally attractive.

  7. Electrochemical impedance study and performance of PdNi nanoparticles as cathode catalyst in a polymer electrolyte membrane fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Ramos-Sanchez, G.; Santana-Salinas, A.; Vazquez-Huerta, G.; Solorza-Feria, O. [Inst. Politenico Nacional, Centro de Investigacion y de Estudios Avanzados, Mexico City (Mexico). Dept. de Quimica

    2010-07-15

    Polymer electrolyte membrane fuel cells (PEMFC) convert the energy stored in hydrogen and oxygen molecules directly into electricity. However, technical and economic challenges must be overcome to address cost, performance and stability issues associated with membrane electrode assemblies (MEA). The oxygen reduction reaction (ORR) which takes place in the cathode is the limiting reaction due to the slow kinetics of ORR on metals, including platinum (Pt). For that reason, much research has gone into finding catalyst materials with a similar or greater performance than Pt. Bimetallic palladium (Pd) based catalysts have been considered as alternative materials for ORR. In this study, a carbon-dispersed bimetallic PdNi was prepared by borohydride reduction using PdCl{sub 2} and NiCl{sub 2} as precursors in a tetrahydrofuran (THF) solution. The PdNi loading and weight percentage were optimized using the Simplex method. The MEA performance was evaluated at optimum conditions using the PdNi electrocatalyst as the cathode and a Pt-Etek carbon cloth as the anode. The maximum power density of 122 mW per cm{sup 2} was reached with 45 percent of PdNi wt percent at 30 psi and 80 degrees C. The catalytic activity and the mechanism of the ORR on PdNi, in 0.5M H{sub 2}SO{sub 4} was investigated using electrochemical impedance spectroscopy. The Tafel slope and the charge transfer coefficient were obtained from the impedance spectra at optimum condition of PdNi loading and PdNi wt percent. 24 refs., 2 tabs., 5 figs.

  8. 聚乙烯亚胺包埋无色纳米银抗菌剂制备及协同抗菌效果研究∗%Preparation of colorless polyethyleneimine-silver nanoparticles antibacterial agent and their synergistic antibacterial effect

    Institute of Scientific and Technical Information of China (English)

    汤建新; 董林利; 苏伟; 王霜霜; 许利剑

    2015-01-01

    In this study,polyethyleneimine (PEI)-capped silver nanoparticles (PEI-AgNPs)antibacterial agent were synthesized in the presence of sodium borohydride (NaBH4 )and PEI by chemical reduction method.Ultra-violet spectrophotometer and SEM were used to study the influence of temperature and molar radio of PEI and Ag+ on synthesis of antibacterial agent.Moreover,in order to get the best preparation technology of PEI-Ag-NPs antimicrobial agent with good antimicrobial activity and excellent colloidal stability,activity of silver nano-particles and PEI was also carried out using inhibition zones test method.The results indicated that the PEI-Ag-NPs antibacterial agent which had core shell structure,good antimicrobial activity and excellent colloidal stabili-ty because of PEI.The silver nanoparticles biocides with good property could be synthesized when the molar ra-dio of PEI and Ag+ was 2∶1-0.6∶1 at 45 ℃.Meanwhile,the synergistic antibacterial effect of PEI on silver antibacterial was also revealed.%以高枝化聚乙烯亚胺(PEI)为稳定剂,硼氢化钠为还原剂,利用化学还原法制备了纳米银抗菌剂。探讨了温度、PEI与 Ag+的摩尔比对纳米银抗菌剂合成的影响,利用紫外分光光度法及扫描电镜对合成纳米银抗菌剂进行了表征,利用抑菌圈实验分别对纳米银及PEI进行了抑菌性能测试,筛选出稳定性好抑菌性强的纳米银抗菌剂制备工艺。实验结果表明,在45℃,PEI与Ag+的摩尔配比在2∶1~0.6∶1条件下能制备无色透明且抑菌性强的具有核壳结构的纳米银抗菌剂,PEI对纳米银抗菌剂具有协同作用。

  9. Ruthenium(0) nanoclusters stabilized by a Nanozeolite framework: isolable, reusable, and green catalyst for the hydrogenation of neat aromatics under mild conditions with the unprecedented catalytic activity and lifetime.

    Science.gov (United States)

    Zahmakiran, Mehmet; Tonbul, Yalçin; Ozkar, Saim

    2010-05-12

    The hydrogenation of aromatics is a ubiquitous chemical transformation used in both the petrochemical and specialty industry and is important for the generation of clean diesel fuels. Reported herein is the discovery of a superior heterogeneous catalyst, superior in terms of catalytic activity, selectivity, and lifetime in the hydrogenation of aromatics in the solvent-free system under mild conditions (at 25 degrees C and 42 +/- 1 psig initial H(2) pressure). Ruthenium(0) nanoclusters stabilized by a nanozeolite framework as a new catalytic material is reproducibly prepared from the borohydride reduction of a colloidal solution of ruthenium(III)-exchanged nanozeolites at room temperature and characterized by using ICP-OES, XRD, XPS, DLS, TEM, HRTEM, TEM/EDX, mid-IR, far-IR, and Raman spectroscopy. The resultant ruthenium(0) nanoclusters hydrogenate neat benzene to cyclohexane with 100% conversion under mild conditions (at 25 degrees C and 42 +/- 1 psig initial H(2) pressure) with record catalytic activity (initial TOF = 5430 h(-1)) and lifetime (TTO = 177 200). They provide exceptional catalytic activity not only in the hydrogenation of neat benzene but also in the solvent-free hydrogenation of methyl substituted aromatics such as toluene, o-xylene, and mesitylene under otherwise identical conditions. Moreover, they are an isolable, bottleable, and reusable catalyst in the hydrogenation of neat aromatics. When the isolated ruthenium(0) nanoclusters are reused, they retain 92% of their initial catalytic activity even for the third run in the hydrogenation of neat benzene under the same conditions as those of the first run. The work reported here also includes (i) far-infrared spectroscopic investigation of nanozeolite, ruthenium(III)-exchanged-nanozeolite, and ruthenium(0) nanoclusters stabilized by a nanozeolite framework, indicating that the host framework remains intact after the formation of a nanozeolite framework stabilized ruthenium(0) nanoclusters; (ii) the

  10. Preparation of PtSnCu/C and PtSn/C electrocatalysts and activation by dealloying processes for ethanol electrooxidation

    International Nuclear Information System (INIS)

    PtSnCu/C (with different Pt:Sn:Cu atomic ratios) and PtSn/C (50:50) electrocatalysts were prepared by borohydride (BR) and alcohol-reduction (AR) processes using H2PtCl6.6H2O, SnCl2.2H2O and CuCl2.2H2O as metal sources, NaBH4 and ethylene glycol as reducing agents, 2-propanol and ethylene glycol/water as solvents and carbon black as support. In a further step, these electrocatalysts were activated by chemical (CD) and electrochemical (ED) dealloying processes through acid treatment and thin porous coating technique, respectively. These materials were characterized by energy dispersive X-ray, Xray diffraction, transmission electron microscopy, line scan energy dispersive Xray and cyclic voltammetry. Electrochemical studies for ethanol electro-oxidation were performed by cyclic voltammetry, chronoamperometry and in single Direct Ethanol Fuel Cell using Membrane Electrode Assembly (MEA). The anodic effluents were analysed by gas chromatography. The X-ray diffractograms of the as-synthesized electrocatalysts showed the typical face-centered cubic structure (FCC) of platinum and its alloys. After dealloying, the X-ray diffractograms showed that the Pt FCC structure was preserved. The crystallite sizes of the assynthesized electrocatalysts were in the range of PtSnCu/C (50:40:10) AR/ED > PtSnCu/C (50:10:40) BR/CD. PtSn/C (50:50) BR/CD, PtSnCu/C (50:10:40) BR/CD, PtSnCu/C (50:40:10) AR/CD electrocatalysts and Pt/C BASF, PtSn/C (75:25) BASF commercial electrocatalysts were tested in single Direct Ethanol Fuel Cell. The results showed the following performance for ethanol electro-oxidation: PtSn/C (50:50) BR/CD > PtSnCu/C (50:40:10) AR/CD > PtSnCu/C > PtSn/C (75:25) BASF > PtSnCu/C (50:10:40) BR/CD > Pt/C BASF. (author)

  11. Subnanometer Control of Mean Core Size during Mesofluidic Synthesis of Small (D(core) < 10 nm) Water-Soluble, Ligand-Stabilized Gold Nanoparticles.

    Science.gov (United States)

    Elliott, Edward W; Haben, Patrick M; Hutchison, James E

    2015-11-01

    A convenient, single-step synthesis is reported that produces ligand-stabilized, water-soluble gold nanoparticles (AuNPs) with subnanometer-level precision of the mean core diameter over a range of 2-9 nm for a series of desired surface chemistries. The synthesis involves the reduction of a Au(III) species with sodium borohydride in the presence of a functionalized alkyl thiosulfate (Bunte salt) to yield thiolate-protected AuNPs. A key advantage of this synthesis is that simply adjusting the pH of the gold salt solution leads to control over the AuNP core size. The speciation of Au(III), and therefore the kinetics for its reduction and the core size produced, depends upon pH. The use of pH as the sole variable to control core size is a more reliable and convenient method than traditional approaches that rely on adjusting the concentrations and ratios of ligand, metal salt, and reducing agent. The average core size increased as the pH was raised for each ligand studied. Because the influence of pH was different for each of the ligands, working curves were plotted for each ligand to identify conditions to synthesize particles with specific, targeted core diameters. Using this approach, reaction conditions can be rapidly optimized using a combination of a mesofluidic reactor and small-angle X-ray scattering (SAXS) size analysis. The use of the mesofluidic reactor was needed to ensure fast mixing given the rapid kinetics for core formation. Using the reactor, it is possible to obtain reproducible sizes across multiple syntheses (<1-2% core size variation) and subnanometer control of the mean core dimensions. The synthetic method demonstrated here provides an attractive alternative to two-step syntheses involving ligand exchange because it is more efficient and eliminates the possibility of nanoparticle core size changes during exchange steps. This approach enables the development of "size ladders" of particles with the same surface chemistry for investigations of

  12. Effects of the addition of an organic polymer on the hydrolysis of sodium tetrahydroborate in batch reactors

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, M.J.F.; Pinto, A.M.F.R. [Centro de Estudos de Fenomenos de Transporte, Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias s/n, 4200-465 Porto (Portugal); Fernandes, V.R.; Rangel, C.M. [Laboratorio Nacional de Energia e Geologia - LNEG, Fuel Cells and Hydrogen Unit, Estrada do Paco do Lumiar 22, 1649-038 Lisboa (Portugal); Gales, L. [Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto and Instituto de Ciencias Biomedicas Abel Salazar, Largo Prof. Abel Salazar 2, 4099-003 Porto (Portugal)

    2010-10-15

    An experimental study is presented both on the generation and storage of molecular hydrogen (H{sub 2}) by small additions of an organic polymer -carboxymethyl cellulose (CMC) - to sodium borohydride (NaBH{sub 4}) through the alkaline hydrolysis, in the presence of a powdered nickel-ruthenium based catalyst reused from 274 to 282 times. The experiments were performed at 45 C in two batch reactors with internal volumes of 0.229 L and 0.369 L, made of stainless-steel with bottom conical shape, positioned vertically. The results showed that working at moderate pressures, up to 2.7 MPa, increases slightly the H{sub 2} dissolution in the liquid phase, enhanced by the changing of the polarity of the remained solution inside the reactor: a value of 0.182 for dimensionless H{sub 2} solubility in the liquid phase with 0.25 wt% CMC was found, at 45 C, based on Henry's law. As a consequence, sodium tetrahydroxoborate, NaB(OH){sub 4} by-product was produced in the presence of CMC additive, showing the absence of crystalline water in its crystal structure (NaB(OH){sub 4} presents structural water, with boron atoms linked to four hydroxyl groups). This new finding never reported to form at < 50 C, has a positive impact in recyclability costs of NaBO{sub 2} back to NaBH{sub 4} due to the elimination of two energy consuming steps in the metaborate dehydration kinetics. In fact our system of compressed hydrogen, shows that both H{sub 2} generation rates and yields and hydrogen storage capacities can be augmented, the latter to reach {approx} 6 wt%, by adding small amounts of an organic polymer (CMC) to the classic NaBH{sub 4} hydrolysis, performed with stoichiometric amount of water. The eventual success of this new route will depend upon developing a advantageous method of converting borates into tetrahydroborate and also finding materials (chemicals) which enhance the solubility of H{sub 2

  13. Nb-TiO{sub 2} supported platinum nanocatalyst for oxygen reduction reaction in alkaline solutions

    Energy Technology Data Exchange (ETDEWEB)

    Elezovic, N.R., E-mail: nelezovic@tmf.bg.ac.rs [Institute for Multidisciplinary Research, University of Belgrade, Kneza Viseslava 1, Belgrade (Serbia); Babic, B.M. [Vinca Institute of Nuclear Sciences, Belgrade (Serbia); Radmilovic, V.R. [National Center for Electron Microscopy, LBNL University of California, Berkely (United States); Vracar, Lj.M.; Krstajic, N.V. [Faculty of Technology and Metallurgy, University of Belgrade, Belgrade (Serbia)

    2011-10-30

    Highlights: > Nb doped TiO{sub 2} catalyst support was successfully synthesized. > Synthesized support surface area was much higher comparing with sub-stoichiometric titanium oxides as supporting material. > The Nb-TiO{sub 2} supported Pt catalyst was successfully prepared and characterized by TEM technique. > Nb doped TiO{sub 2} support seems to be more suitable than carbon based support. > The change in the rate-determining step was proposed for reaction mechanism explanation. - Abstract: Platinum based nanocatalyst at home made Nb-TiO{sub 2} support was synthesized and characterized as the catalyst for oxygen reduction reaction in 0.1 mol dm{sup -3} NaOH, at 25 deg. C. Nb doped TiO{sub 2} catalyst support, containing 5% of Nb, has been synthesized by modified acid-catalyzed sol-gel procedure in non-aqueous medium. BET and X-ray diffraction (XRD) techniques were applied for characterization of synthesized supporting material. XRD analysis revealed only presence of anatase TiO{sub 2} phase in synthesized support powder. Existence of any peaks belonging to Nb compounds has not been observed, indicating Nb incorporated into the lattice. Nb-TiO{sub 2} supported Pt nanocatalyst synthesized, using borohydride reduction method, was characterized by TEM and HRTEM techniques. Platinum nanoparticles distribution, over Nb doped TiO{sub 2} support, was quite homogenous. Mean particle size of about 4 nm was found with no pronounced particle agglomeration. Electrochemical techniques: cyclic voltammetry and linear sweep voltammetry at rotating disc electrode were applied in order to study kinetics and estimate catalytic activity of this new catalyst for the oxygen reduction reaction in alkaline solution. Two different Tafel slopes were found: one close to -90 mV dec{sup -1} in low current density region and other approximately -200 mV dec{sup -1} in high current density region, which is in good accordance with literature results for oxygen reduction at Pt single crystals, as

  14. The Stereoselective Reduction of Acyl Protected 4-Amino-3,4-dihydro-1 (2H)-naphthalenone%酰基保护的4-氨基-3,4-二氢1(2H)-萘酮的立体选择性还原反应

    Institute of Scientific and Technical Information of China (English)

    王超; 黄焰根; 孟卫东

    2013-01-01

    1,2,3,4-四氢-1-萘胺及其衍生物是一类重要的药物合成中间体.从光学纯的(R)-和(S)-1,2,3,4-四氢-1-萘胺出发,首先经乙酰化、苯甲酰化和邻苯二甲酰化反应制备相应酰胺,然后在高锰酸钾作用下氧化生成了氨基萘酮衍生物,收率为65%~85 %.这些不同酰基保护的氨基萘酮衍生物经硼氢化钠(NaBH4)和二异丁基氢化铝(DIBAL-H)还原后得到两种构型的氨基萘醇混合产物,经二维核磁共振氢谱的核磁欧沃豪斯效应(NOE)推断,此还原反应的主产物是顺式构型的氨基萘醇,当(R)-或(S)-邻苯二甲酰化的氨基萘酮经DIBAL-H还原后主产物为顺式的氨基萘醇4ca和7ba,其非对映异构体过量(de)百分比分别为92.6%和98.2%.%1,2,3,4-Tetrahydronaphthalen-1-amine and its derivative were a series of important synthetic intermediates for bioactive compounds. Acylation of optically pure (R)-and (S)-1, 2, 3, 4-tetrahydronaphthalen-1-amine with acetic anhydride, benzoyl chloride and phthalic anhydride followed by oxidation with potassium permanganate to give acylated aminonaphthyl ketones in yields of 65% ~ 85%. These aminonaphthyl ketones were reduced stereoselectively by sodium borohydride(NaBH4) or diisobutylaluminium hydride(DIBAL-H) to afford the aminonaphthyl alcohols mainly in cis-form, which was confirmed by nuclear Overhauser effect (NOE) obtained by 2D 1H NMR. When (R)-and (S)-phthalic protected aminonaphthyl ketone was reduced with DIBAL-H, cis-aminonaphthyl alcohols 4ca and 7ba were obtained as major product in diastereomeric excesses'(de) percentages of 92.6% and 98.2%, respectively.

  15. 遇水放出易燃气体类危险品检测仪的开发和应用%Development and application of tester for dangerous chemicals emitting flammable gases in contact with water

    Institute of Scientific and Technical Information of China (English)

    于晓; 车礼东; 冯真真

    2013-01-01

    Objective:According to the classification and properties of dangerous goods in "Recommendation on the Transport of Dangerous Goods (RTDG)" issued by United Nations,to develop a tester for dangerous goods emitting flammable gases in contact with water.Methods:The tester was made up of sample reaction system,pressure monitoring and control system,data collection and processing system.The volume and emitting rate of gas released from reaction could be acquired by monitoring the quality of gas drainage.Results:By classification test of local export dangerous goods such as sodium hydride and potassium borohydride,the test results were found in accordance with classifications in dangerous goods list of RTDG and related literatures.Conclusion:The tester was proven to conform to theoretical classification procedure and resuhs evaluation of RTDG,with safe operation and precision.The test results could also be traced easily.%目的:根据联合国《关于危险货物运输的建议书》中第4.3类遇水放出易燃气体类危险品的危险特性,研制了遇水放出易燃气体类危险品检测仪.方法:检测仪主要由样品反应系统、压力监测控制系统、数据采集处理系统组成.通过监测试验产生气体所排出水的质量换算出气体体积和释放速率.结果:对山东省出口较多的氢化钠、硼氢化钾等危险品的实际分类检测,发现试验结果与《建议书》中“危险货物一览表”和相关文献的分类结果一致.结论:该检测仪符合《建议书》提出的理论分类试验步骤和结果评估方案,且操作安全、检测准确率高,具有可溯源性.

  16. Reactivity patterns of transition metal hydrides and alkyls

    Energy Technology Data Exchange (ETDEWEB)

    Jones, W.D. II

    1979-05-01

    The complex PPN/sup +/ CpV(CO)/sub 3/H/sup -/ (Cp=eta/sup 5/-C/sub 5/H/sub 5/ and PPN = (Ph/sub 3/P)/sub 2/) was prepared in 70% yield and its physical properties and chemical reactions investigated. PPN/sup +/ CpV(CO)/sub 3/H/sup -/ reacts with a wide range of organic halides. The organometallic products of these reactions are the vanadium halides PPN/sup +/(CpV(C)/sub 3/X)/sup -/ and in some cases the binuclear bridging hydride PPN/sup +/ (CpV(CO)/sub 3/)/sub 2/H/sup -/. The borohydride salt PPN/sup +/(CpV(CO)/sub 3/BH/sub 4/)/sup -/ has also been prepared. The reaction between CpV(CO)/sub 3/H/sup -/ and organic halides was investigated and compared with halide reductions carried out using tri-n-butyltin hydride. Results demonstrate that in almost all cases, the reduction reaction proceeds via free radical intermediates which are generated in a chain process, and are trapped by hydrogen transfer from CpV(CO)/sub 3/H/sup -/. Sodium amalgam reduction of CpRh(CO)/sub 2/ or a mixture of CpRh(CO)/sub 2/ and CpCo(CO)/sub 2/ affords two new anions, PPN/sup +/ (Cp/sub 2/Rh/sub 3/(CO)/sub 4/)/sup -/ and PPN/sup +/(Cp/sub 2/RhCo(CO)/sub 2/)/sup -/. CpMo(CO)/sub 3/H reacts with CpMo(CO)/sub 3/R (R=CH/sub 3/,C/sub 2/H/sub 5/, CH/sub 2/C/sub 6/H/sub 5/) at 25 to 50/sup 0/C to produce aldehyde RCHO and the dimers (CpMo(CO)/sub 3/)/sub 2/ and (CpMo(CO)/sub 2/)/sub 2/. In general, CpV(CO)/sub 3/H/sup -/ appears to transfer a hydrogen atom to the metal radical anion formed in an electron transfer process, whereas CpMo(CO)/sub 3/H transfers hydride in a 2-electron process to a vacant coordination site. The chemical consequences are that CpV(CO)/sub 3/H/sup -/ generally reacts with metal alkyls to give alkanes via intermediate alkyl hydride species whereas CpMo(CO)/sub 3/H reacts with metal alkyls to produce aldehyde, via an intermediate acyl hydride species.

  17. Reactivity patterns of transition metal hydrides and alkyls

    International Nuclear Information System (INIS)

    The complex PPN+ CpV(CO)3H- (Cp=eta5-C5H5 and PPN = (Ph3P)2) was prepared in 70% yield and its physical properties and chemical reactions investigated. PPN+ CpV(CO)3H- reacts with a wide range of organic halides. The organometallic products of these reactions are the vanadium halides PPN+[CpV(C)3X]- and in some cases the binuclear bridging hydride PPN+ [CpV(CO)3]2H-. The borohydride salt PPN+[CpV(CO)3BH4]- has also been prepared. The reaction between CpV(CO)3H- and organic halides was investigated and compared with halide reductions carried out using tri-n-butyltin hydride. Results demonstrate that in almost all cases, the reduction reaction proceeds via free radical intermediates which are generated in a chain process, and are trapped by hydrogen transfer from CpV(CO)3H-. Sodium amalgam reduction of CpRh(CO)2 or a mixture of CpRh(CO)2 and CpCo(CO)2 affords two new anions, PPN+ [Cp2Rh3(CO)4]- and PPN+[Cp2RhCo(CO)2]-. CpMo(CO)3H reacts with CpMo(CO)3R (R=CH3,C2H5, CH2C6H5) at 25 to 500C to produce aldehyde RCHO and the dimers [CpMo(CO)3]2 and [CpMo(CO)2]2. In general, CpV(CO)3H- appears to transfer a hydrogen atom to the metal radical anion formed in an electron transfer process, whereas CpMo(CO)3H transfers hydride in a 2-electron process to a vacant coordination site. The chemical consequences are that CpV(CO)3H- generally reacts with metal alkyls to give alkanes via intermediate alkyl hydride species whereas CpMo(CO)3H reacts with metal alkyls to produce aldehyde, via an intermediate acyl hydride species

  18. Preparation, characterization, and biodistribution study of technetium-99m labelled crotalus venom

    International Nuclear Information System (INIS)

    Technetium-99m (99mTc) is a radionuclide widely used for nuclear medical examination. Called the workhorse of nuclear medicine, 99mTc is the favoured choice because it has the appropriate physical and chemical characteristics for imaging. The gamma radiation emitted by 99mTc has the appropriate energy (140 keV) to provide high efficiency detection with the advantage of reduced radiation burden for the patient and environmental (half-life of 6 h). Crotalus venom (CV) has been tested in a very few human cases and it has been shown to reduce tumours. Our group has shown that CV has antitumoural effects against some brain tumours in vitro. Pharmacokinetics and tissue distribution studies are very important for clinical use. The aim of the present study was to obtain an analogue of CV labelled with 99mTc which preserves its biological activity for use in biodistribution and binding studies. A direct method for 99mTc-labelling venom has been evaluated according to Pauwels, et al. The method employs stannous chloride and sodium borohydride as reducing agents. By altering the reaction conditions high yield of labelled venom was achieved. Labeling yield was estimated using chromatographic systems. Biological activity was assessed by haemolytic activity study. Comparing haemolytic activities of labelled and unlabeled venom we observed that neither 99mTc-CV nor CV caused direct lysis on washed erythrocytes. However, both of them caused indirect hemolysis provided that the incubation medium contained an exogenous source of lecithin. So, the biological activity of CV was preserved after labeling. Biodistribution of 99mTc-CV was evaluated in mice. Male swiss mice were injected i.p. with 99mTc-CV, vital organs were isolated and their respective radioactivities were measured. High radioactivity was found in the kidneys suggesting renal excretion. On the other hand, this radioactivity was displaced in animals pre-treated with excess of non labelled CV (not shown). These data show

  19. Structure of pestalotan, a highly branched (1----3)-beta-D-glucan elaborated by Pestalotia sp. 815, and the enhancement of its antitumor activity by polyol modification of the side chains.

    Science.gov (United States)

    Misaki, A; Kawaguchi, K; Miyaji, H; Nagae, H; Hokkoku, S; Kakuta, M; Sasaki, T

    1984-07-01

    Pestalotia sp. 815, a newly isolated fungus, produces extracellularly a highly (1----6)-branched (1----3)-beta-D-glucan in high yield when grown in a D-glucose-containing medium. This extracellular glucan, designated "Pestalotan", has [alpha]25D-0.1 degree (c 0.5, M NaOH) and a molecular weight greater than 2 X 10(6). Chemical and enzymic studies indicated that pestalotan has a very highly branched structure containing a back-bone chain of beta-D-(1----3)-linked D-glucosyl residues, and three out of five D-glucosyl residues are substituted at O-6, mostly with single D-glucosyl groups, and a very few with short beta-(1----6)-linked oligosaccharide units. This D-glucan becomes water-insoluble after isolation from the culture filtrate followed by dehydration, and shows moderate growth-inhibitory activities against mouse-implanted tumors. However, when the D-glucosyl groups of the side chains were modified by periodate oxidation and borohydride reduction, the resulting, still water-insoluble, D-glucan polyol exhibited potent antitumor activities, confirming that the attachment of many polyhydroxy groups to the beta-D-(1----3)-linked D-glucan back-bone gives a remarkable enhancement effect on the antitumor activity of the branched D-glucan. Prolonged treatment of the D-glucan polyol by ultrasonic irradiation afforded a low-molecular-weight D-glucan polyol (SD-pestalotan polyol), without alteration of its chemical structure. The water-soluble, SD-pestalotan polyol, having a molecular weight of 4.7 X 10(5), exhibited remarkable antitumor activities against both allogeneic and syngeneic, mouse-implanted tumors, at small dosages (1-5 mg/kg for 10 days) by intraperitoneal administration. A comparison of values of the molecular weight of SD-pestalotan polyol, estimated by 3-MPa l.c. for the aqueous solution and the dimethyl sulfoxide solution, strongly suggested that the D-glucan polyol must form a triple-chain conformation in aqueous solution. PMID:6547877

  20. Inorganic Nanoparticle Nucleation on Polymer Matrices

    Science.gov (United States)

    Kosteleski, Adrian John

    The introduction of inorganic nanoparticles into organic materials enhances both the mechanical and chemical properties of the material. Metallic nanoparticles, like silver and gold, have been introduced into polymers for use as antimicrobial coatings or dielectric materials, respectively. The challenge in creating these materials currently is the difficulty to homogeneously disperse the particles throughout the polymer matrix. The uneven dispersion of nanoparticles can lead to less than optimal quality and undesired properties. By creating a polymer nanocomposite material with well-controlled size inorganic materials that are evenly dispersed throughout the polymer matrix; we can improve the materials performance and properties. The objective for this research is to use polymer networks for the in situ mineralization of silver and other metallic materials to create intricate inorganic structures. The work performed here studied the ability to nucleate silver nanoparticles using poly (acrylic acid) (PAA) as the templating agent. Ionic silver was chemically reduced by sodium borohydride (NaBH4) in the presence of PAA. The effect of varying reactant concentrations of silver, NaBH 4, and PAA on particle size was studied. Reaction conditions in terms of varying temperature and pH levels of the reaction solution were monitored to observe the effect of silver nanoparticle size, shape, and concentration. By monitoring the UV spectra over time the reaction mechanism of the silver reduction process was determined to be an autocatalytic process: a period of slow, continuous nucleation followed by rapid, autocatalytic growth. The reaction kinetics for this autocatalytic process is also reported. PAA was crosslinked both chemically and physically to 3 biopolymers; ELP, an elastin like peptide, cotton fabrics, and calcium alginate hydrogels. Various compositions of PAA were physically crosslinked with calcium alginate gels to design an antimicrobial hydrogel for use in wound