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Sample records for metal alkoxides templates

  1. Metal alkoxides and methods of making same

    DOEpatents

    Hentges, Patrick J.; Greene, Laura H.; Pafford, Margaret Mary; Westwood, Glenn; Klemperer, Walter G.

    2005-01-04

    A method of making a superconducting structure includes depositing a metal alkoxide on a surface of a metal and hydrolyzing the metal alkoxide on the surface to form a pinhole-free film. The metal is a superconductor. The metal alkoxide may be a compound of formula (I): where M is zirconium or hafnium, and the purity of the compound is at least 97% as measured by NMR spectroscopy.

  2. All-alkoxide synthesis of strontium-containing metal oxides

    DOEpatents

    Boyle, Timothy J.

    2001-01-01

    A method for making strontium-containing metal-oxide ceramic thin films from a precursor liquid by mixing a strontium neo-pentoxide dissolved in an amine solvent and at least one metal alkoxide dissolved in a solvent, said at least one metal alkoxide selected from the group consisting of alkoxides of calcium, barium, bismuth, cadmium, lead, titanium, tantalum, hafnium, tungsten, niobium, zirconium, yttrium, lanthanum, antimony, chromium and thallium, depositing a thin film of the precursor liquid on a substrate, and heating the thin film in the presence of oxygen at between 550 and 700.degree. C.

  3. Virus templated metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Aljabali, Alaa A. A.; Barclay, J. Elaine; Lomonossoff, George P.; Evans, David J.

    2010-12-01

    Plant viruses are considered as nanobuilding blocks that can be used as synthons or templates for novel materials. Cowpea mosaic virus (CPMV) particles have been shown to template the fabrication of metallic nanoparticles by an electroless deposition metallization process. Palladium ions were electrostatically bound to the virus capsid and, when reduced, acted as nucleation sites for the subsequent metal deposition from solution. The method, although simple, produced highly monodisperse metallic nanoparticles with a diameter of ca. <=35 nm. CPMV-templated particles were prepared with cobalt, nickel, iron, platinum, cobalt-platinum and nickel-iron.Plant viruses are considered as nanobuilding blocks that can be used as synthons or templates for novel materials. Cowpea mosaic virus (CPMV) particles have been shown to template the fabrication of metallic nanoparticles by an electroless deposition metallization process. Palladium ions were electrostatically bound to the virus capsid and, when reduced, acted as nucleation sites for the subsequent metal deposition from solution. The method, although simple, produced highly monodisperse metallic nanoparticles with a diameter of ca. <=35 nm. CPMV-templated particles were prepared with cobalt, nickel, iron, platinum, cobalt-platinum and nickel-iron. Electronic supplementary information (ESI) available: Additional experimental detail, agarose gel electrophoresis results, energy dispersive X-ray spectra, ζ-potential measurements, dynamic light scattering data, nanoparticle tracking analysis and an atomic force microscopy image of Ni-CPMV. See DOI: 10.1039/c0nr00525h

  4. Preparation of oxide glasses from metal alkoxides by sol-gel method

    NASA Technical Reports Server (NTRS)

    Kamiya, K.; Yoko, T.; Sakka, S.

    1987-01-01

    An investigation is carried out on the types of siloxane polymers produced in the course of the hydrolysis of silicon tetraethoxide, as well as the preparation of oxide glasses from metal alkoxides by the sol-gel method.

  5. Impact of metal-alkoxide functionalized linkers on H2 binding: A density functional study

    NASA Astrophysics Data System (ADS)

    Banu, Tahamida; Ghosh, Avik; Das, Abhijit K.

    2016-08-01

    The effect of metal-alkoxide functionalization of different organic linkers on the H2 binding is investigated employing DFT approach. While analyzing the H2 binding interaction of magnesium-alkoxide modified benzene, naphthalene, anthracene and pyrene linkers, we find their comparable affinity toward H2 molecules. Six-member alkoxide ring containing naphthalene and pyrene systems interact with the H2 molecules in a comparatively better way than their five-member analogues. AIM, NBO and LMO-EDA analyses have been performed to comprehend the bonding nature between Mg center and the H2 molecules. Polarization along with the charge transfer interactions play significant role in stabilizing the systems.

  6. Metal nanodisks using bicellar templates

    SciTech Connect

    Song, Yujiang; Shelnutt, John A

    2013-12-03

    Metallic nanodisks and a method of making them. The metallic nanodisks are wheel-shaped structures that that provide large surface areas for catalytic applications. The metallic nanodisks are grown within bicelles (disk-like micelles) that template the growth of the metal in the form of approximately circular dendritic sheets. The zero-valent metal forming the nanodisks is formed by reduction of a metal ion using a suitable electron donor species.

  7. Photoinduced manipulation of the molecular assembly in heteroleptic titanium metal alkoxides for use in optical devices

    NASA Astrophysics Data System (ADS)

    Schneider, Zachary Vernon

    The manipulation of molecular structures is an important enabling technology for future advances in nanotechnology. The ability to control the synthesis of nanostructured materials, such as the bond formation and geometry of a molecule is of great significance to nanoscience as nanosystems are constructed from these smaller units. Influencing the assembly of molecular structures at the early stages of material formation can modify the ensuing molecular aggregate structure with the potential for impact in a broad range of optical, chemical, and biological applications. Heteroleptic titanium metal alkoxides (OPy)2Ti(4MP)2 and (OPy)2Ti(TAP)2, where OPy = OC6H 6N, 4MP = OC6H4(SH)-4, and TAP = OC6H 2(CH2N(CH3)2)3-2,4,6 were investigated as precursors for thin film and solution-based synthesis of oxide materials via the photoactivation of intermolecular reactions (e.g. hydrolysis/condensation) at selected ligand sites about the metal center. Manipulation of the molecular structure of these photosensitive metal alkoxides was achieved through the use of optical irradiation parameters, such as the tuning of the excitation wavelength, total optical fluence, and pulse energy intensity. Irradiating these metal alkoxides with UV-light was seen to cause photodisruption in the ligand groups leading to the formation of Ti-O-Ti linking via hydrolysis and condensation reactions. In spin-coated (OPy)2Ti(TAP)2 films, these photoinduced bridge bond formations resulted in an increase in refractive index and film densification as well as produced an insoluble film when rinsed in pyridine. By making use of these photoinduced film properties, the formation of physical relief structures from spin-coated (OPy)2Ti(TAP) 2 films was demonstrated along with the ability to photopattern sub-micron and nanometer features. In addition, the micro- and nanostructure of thin films were optically manipulated through several deposition methods; a novel dip-coated in-situ photodeposition technique was

  8. Low temperature synthesis of monolithic transparent Ta2O5 gels from hydrolysis of metal alkoxide

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.

    1993-01-01

    Tantalum oxide gels in the form of transparent monoliths and powder were prepared from hydrolysis of tantalum pentaethoxide under controlled conditions using different mole ratios of Ta(OC2H5)5:C2H50H:H20:HCl. Alcohol acts as the mutual solvent and HCl as the deflocculating agent. For a fixed alkoxide:water:HCl ratio, time of gel formation increased with the alcohol to alkoxide mole ratio. Thermal evolution of the physical and structural changes in the gel was monitored by differential thermal analysis, thermogravimetric analysis, x-ray diffraction, and infrared spectroscopy. On heating to approximately 400 C, the amorphous gel crystallized into the low temperature orthorhombic phase Beta-Ta2O5, which transformed into the high temperature tetragonal phase Alpha-Ta2O5 when further heated to approximately 1450 C. The volume fraction of the crystalline phase increased with the firing temperature. The Alpha-Ta205 converted back into the low temperature phase, Beta-Ta2O5, on slow cooling through the transformation temperature of 1360 C indicating a slow but reversible transformation.

  9. Alkali metal yttrium neo-pentoxide double alkoxide precursors to alkali metal yttrium oxide nanomaterials

    DOE PAGES

    Boyle, Timothy J.; Neville, Michael L.; Sears, Jeremiah Matthew; Cramer, Roger

    2016-03-15

    In this study, a series of alkali metal yttrium neo-pentoxide ([AY(ONep)4]) compounds were developed as precursors to alkali yttrium oxide (AYO2) nanomaterials. The reaction of yttrium amide ([Y(NR2)3] where R=Si(CH3)3) with four equivalents of H-ONep followed by addition of [A(NR2)] (A=Li, Na, K) or Ao (Ao=Rb, Cs) led to the formation of a complex series of AnY(ONep)3+n species, crystallographically identified as [Y2Li3(μ3-ONep)(μ3-HONep)(μ-ONep)5(ONep)3(HONep)2] (1), [YNa2(μ3-ONep)4(ONep)]2 (2), {[Y2K3(μ3-ONep)3(μ-ONep)4(ONep)2(ηξ-tol)2][Y4K2(μ4-O)(μ3-ONep)8(ONep)4]•ηx-tol]} (3), [Y4K2(μ4-O)(μ3-ONep)8(ONep)4] (3a), [Y2Rb3(μ4-ONep)3(μ-ONep)6] (4), and [Y2Cs4(μ6-O)(μ3-ONep)6(μ3-HONep)2(ONep)2(ηx-tol)4]•tol (5). Compounds 1–5 were investigated as single source precursors to AYOx nanomaterials following solvothermal routes (pyridine, 185 °C for 24h). The final products after thermal processing weremore » found by powder X-ray diffraction experiments to be Y2O3 with variable sized particles based on transmission electron diffraction. Energy dispersive X-ray spectroscopy studies indicated that the heavier alkali metal species were present in the isolated nanomaterials.« less

  10. Mixed-metal templated phosphate phases

    SciTech Connect

    Nenoff, T.M.; Jackson, N.B.; Thoma, S.G.; Kohler, S.D.; Harrison, W.T.A.

    1997-08-01

    In an effort to direct the structure formation and subsequently the catalytic properties of novel materials, both organic molecules and transition metals have been systematically incorporated into zinc phosphate materials, and various transition metals in zirconium phosphate materials. The resultant phases in the Zn/P experiments are determined not by the organic template, but by the type and stoichiometric amount of metal incorporated and by the organic template`s anion. Furthermore, only one of the phases, a Ni/Zn/P, shows any acidic catalytic behavior. Similarly, the transition metals incorporated in stoichiometric amounts into the catalytically active novel zirconium phosphate are highly structure directing. Their presence inhibits the formation of the phosphate phase, instead promoting the formation of tetragonal ZrO{sub 2}. The catalytic activity of the products are greatly diminished from the baseline material. The synthesis and characterization methods for each phase will be presented. Characterization techniques employed include single-crystal and powder X-ray diffraction, magnetic susceptibility, thermal analysis, DCP and FTIR.

  11. Surfactant-Templated Mesoporous Metal Oxide Nanowires

    DOE PAGES

    Luo, Hongmei; Lin, Qianglu; Baber, Stacy; Naalla, Mahesh

    2010-01-01

    We demore » monstrate two approaches to prepare mesoporous metal oxide nanowires by surfactant assembly and nanoconfinement via sol-gel or electrochemical deposition. For example, mesoporous Ta 2 O 5 and zeolite nanowires are prepared by block copolymer Pluronic 123-templated sol-gel method, and mesoporous ZnO nanowires are prepared by electrodeposition in presence of anionic surfactant sodium dodecyl sulfate (SDS) surfactant, in porous membranes. The morphologies of porous nanowires are studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses.« less

  12. Cycloaddition of phosphaalkynes to high-oxidation-state metal alkylidenes: Synthesis and characterization of a unique phosphametallacyclobutene via an alkoxide ligand shift

    SciTech Connect

    Jamison, G.M.; Saunders, R.S.; Wheeler, D.R.; McClain, M.D.; Loy, D.A.; Ziller, J.W.

    1996-01-09

    The phosphametallacycle 3, [ArN][RO]Mo=C(t-Bu)P(OR)C(H)(t-Bu) (Ar = 2, 6-(i-Pr){sub 2}-C{sub 6}H{sub 3}, R = CMe(CF{sub 3}){sub 2}), is formed from the cycloaddition of tert-butylphosphaacetylene to the high-oxidation-state molybdenum alkylidene [ArN][RO]{sub 2} Mo=C(H)(t-Bu), accompanied by an alkoxide metal-to-ligand shift. The 1-phospha-3-molybdacyclobut-2-ene has been characterized by multinuclear NMR spectroscopy and its molecular structure determined by X-ray crystallographic analysis. 20 refs., 2 figs.

  13. Preparation and Basic Properties of BaTiO3-BaPbO3 Multilayer Thin Films by Metal-Alkoxides Method

    NASA Astrophysics Data System (ADS)

    Azuma, Takahiro; Takahashi, Sheiji; Kuwabara, Makoto

    1993-09-01

    Preferentially oriented barium titanate (BTO)-barium metaplumbate (BPO) multilayer thin films were prepared by the metal-alkoxides method on MgO single crystals. The BPO layer is an electrode for the BTO layer. Thin films were deposited on cleaved MgO (100) substrates by spin coating. A BTO film of 0.4 μm thickness on the BPO layer shows a dielectric constant of about 400 at room temperature. No formation of reaction phases between BTO and BPO, fired at 800°C to yield a well-crystallized BTO film, was detected in X-ray diffraction analysis.

  14. Silver nanowires-templated metal oxide for broadband Schottky photodetector

    NASA Astrophysics Data System (ADS)

    Patel, Malkeshkumar; Kim, Hong-Sik; Park, Hyeong-Ho; Kim, Joondong

    2016-04-01

    Silver nanowires (AgNWs)-templated transparent metal oxide layer was applied for Si Schottky junction device, which remarked the record fastest photoresponse of 3.4 μs. Self-operating AgNWs-templated Schottky photodetector showed broad wavelength photodetection with high responsivity (42.4 A W-1) and detectivity (2.75 × 1015 Jones). AgNWs-templated indium-tin-oxide (ITO) showed band-to-band excitation due to the internal photoemission, resulting in significant carrier collection performances. Functional metal oxide layer was formed by AgNWs-templated from ITO structure. The grown ITO above AgNWs has a cylindrical shape and acts as a thermal protector of AgNWs for high temperature environment without any deformation. We developed thermal stable AgNWs-templated transparent oxide devices and demonstrated the working mechanism of AgNWs-templated Schottky devices. We may propose the high potential of hybrid transparent layer design for various photoelectric applications, including solar cells.

  15. Precursor directed synthesis - ``molecular'' mechanisms in the Soft Chemistry approaches and their use for template-free synthesis of metal, metal oxide and metal chalcogenide nanoparticles and nanostructures

    NASA Astrophysics Data System (ADS)

    Seisenbaeva, Gulaim A.; Kessler, Vadim G.

    2014-05-01

    This review provides an insight into the common reaction mechanisms in Soft Chemistry processes involved in nucleation, growth and aggregation of metal, metal oxide and chalcogenide nanoparticles starting from metal-organic precursors such as metal alkoxides, beta-diketonates, carboxylates and their chalcogene analogues and demonstrates how mastering the precursor chemistry permits us to control the chemical and phase composition, crystallinity, morphology, porosity and surface characteristics of produced nanomaterials.This review provides an insight into the common reaction mechanisms in Soft Chemistry processes involved in nucleation, growth and aggregation of metal, metal oxide and chalcogenide nanoparticles starting from metal-organic precursors such as metal alkoxides, beta-diketonates, carboxylates and their chalcogene analogues and demonstrates how mastering the precursor chemistry permits us to control the chemical and phase composition, crystallinity, morphology, porosity and surface characteristics of produced nanomaterials. To Professor David Avnir on his 65th birthday.

  16. Synthesis, characterization and formation process of transition metal oxide nanotubes using carbon nanofibers as templates

    SciTech Connect

    Ogihara, Hitoshi; Masahiro, Sadakane; Nodasaka, Yoshinobu; Ueda, Wataru

    2009-06-15

    Mono and binary transition metal oxide nanotubes could be synthesized by the immersion of carbon nanofiber templates into metal nitrate solutions and removal of the templates by heat treatment in air. The transition metal oxide nanotubes were composed of nano-crystallites of metal oxides. The functional groups on the carbon nanofiber templates were essential for the coating of these templates: they acted as adsorption sites for the metal nitrates, ensuring a uniform metal oxide coating. During the removal of the carbon nanofiber templates by calcination in air, the metal oxide coatings promoted the combustion reaction between the carbon nanofibers and oxygen. - Graphical abstract: Mono and binary transition metal-oxide nanotubes could be synthesized by the immersion of carbon nanofiber templates into metal nitrate solutions and removal of the templates by heat treatment in air.

  17. Alkoxide routes to Inorganic Materials

    SciTech Connect

    Thomas, George H

    2007-12-01

    An all alkoxide solution chemistry utilizing metal 2-methoxyethoxide complexes in 2-methoxyethanol was used to deposit thin-films of metal oxides on single-crystal metal oxide substrates and on biaxially textured metal substrates. This same chemistry was used to synthesize complex metal oxide nanoparticles. Nuclear Magnetic Resonance spectroscopy was used to study precursor solutions of the alkaline niobates and tantalates. Film crystallization temperatures were determined from x-ray diffraction patterns of powders derived from the metal oxide precursor solutions. Film structure was determined via x-ray diffraction. Film morphology was studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Epitaxial thin-films of strontium bismuth tantalate (SrBi{sub 2}Ta{sub 2}O{sub 9}, SBT) and strontium bismuth niobate (SrBi{sub 2}Nb{sub 2}O{sub 9}, SBN) were deposited on single crystal [1 0 0] magnesium oxide (MgO) buffered with lanthanum manganate (LaMnO{sub 3}, LMO). Epitaxial thin films of LMO were deposited on single crystal [100] MgO via Rf-magnetron sputtering and on single crysal [100] lanthanum aluminate (LaAlO{sub 3}) via the chemical solution deposition technique. Epitaxial thin-films of sodium potassium tantalate (na{sub 0.5}K{sub 0.5}TaO{sub 3}, NKT), sodium potassium niobate (Na{sub 0.5}K{sub 0.5}NbO{sub 3}, NKN) and sodium potassium tantalum niobate (Na{sub 0.5}K{sub 0.5}Ta{sub 0.5}O{sub 3}, NKTN) were deposited on single crystal [1 0 0] lanthanum aluminate and [1 0 0] MgO substrates (NKT and NKN) and biaxially textured metal substrates via the chemical solution deposition technique. Epitaxial growth of thin-films of NKT, NKN and NKTN was observed on LAO and Ni-5% W. Epitaxial growth of thin-films of NKN and the growth of c-axis aligned thin-films of NKT was observed on MgO. Nanoparticles of SBT, SBN, NKT and NKN were synthesized in reverse micelles from alkoxide precursor solutions. X-ray diffraction and transmission electron

  18. Template Synthesis of Nanostructured Metals using Cellulose Nanocrystal

    SciTech Connect

    Shin, Yongsoon; Exarhos, Gregory J.

    2009-11-01

    In this chapter, cellulose nanocrystal (CNXL) has been used as a template and reducing agent for synthesizing nanoscale inorganic solids such as metal oxide, metal carbide, and nanocrystalline metals. CNXL selectively nucleates metal or metal oxide phases in ordered arrangements commensurate with the attendant structure and chemistry of the fiber. The reaction has an analogy to the well-known Tollen’s reagent where addition of an aldehyde or glucose analyte to a glass vessel containing a soluble ammoniacal silver complex causes reduction of the silver to form a mirror on the vessel surface. For the synthesis of TiO2, CNXL produced mesoporous anatase with 5-10 nm particle sizes and 170-200 m2/g surface area after air-calcination. Silica-infiltrated CNXL produced very homogeneous SiC nanowires with 70 nm in diameter at 1400 oC in Ar. For the syntheses of metal nanoparticles, upon addition of aqueous metal ion containing solutions (Cu(II), Ni(II), Ag(I), Au(III), Pd(II), Pt(IV), or even selenite, Se(IV)) into the CNXL suspension, reduction to the metal occurs under hydrothermal conditions to form ordered metal nanostructures. Ni (II) and Cu(II) ions required high temperature (300-400 oC) to be reduced due to their low reduction potentials. However, metal ions including Ag(I), Au(III), Pt(IV), Pd(II), Se(IV) needed lower temperatures (160-200 oC) to be reduced. Enhanced catalytic activity on these templated surfaces has been demonstrated for a methylene-blue dye photo-induced decomposition (Se nanocrystals resident on crystalline cellulose).

  19. Titanium alkoxide compound

    SciTech Connect

    Boyle, Timothy J.

    2007-08-14

    A titanium alkoxide composition is provided, as represented by the chemical formula (OC.sub.6H.sub.5N).sub.2Ti(OC.sub.6H.sub.5NH.sub.2).sub.2. As prepared, the compound is a crystalline substance with a hexavalent titanium atom bonded to two OC.sub.6H.sub.5NH.sub.2 groups and two OC.sub.6H.sub.5N groups with a theoretical molecular weight of 480.38, comprising 60.01% C, 5.04% H and 11.66% N.

  20. Mechanistic and synthetic studies aimed at the development of single-site metal alkoxide catalysts for the generation of polyesters and polycarbonates

    SciTech Connect

    Chisholm, Malcolm

    2010-06-30

    The work proposed herein focuses on the chemistry of metal-oxygen bonds with respect to insertion/enchainment reactions involving epoxides, cyclic esters and carbonates, acid anhydrides and carbon dioxide leading to the formation of polyethers, polyesters and polycarbonates from renewable resources. Particular emphasis is placed on the use of the biologically benign metals magnesium and calcium and the M(3+) ions of aluminum, chromium and cobalt that have a similar ionic radii but different coordination properties arising from their respective d0, d3 and d6 valence shell configurations. The work emphasizes the design and use of single-site metal catalysis involving LMOR initiating and propagating species. For M = Mg and Ca, L is a pyrazolyl borate ligand specifically tailored to the coordination properties of the metal. In addition the ligand is inert with respect to reactions of the substrates under consideration. For the M(3+) ions, L is a substituted porphyrin, namely 5,10,15,20-tetraphenylporphyrin, TPP, 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin, TFPP or 2,3,7,8,12,13,17,18-octaethylporphyrin, which together with Lewis base co-catalysts will allow the elucidation of factors leading to polyethers, polycarbonates and cyclic carbonates in reactions involving epoxides and CO2. Specific attention is given to reactions involving propylene oxide and styrene oxide which commonly show competitive formation of products. Electronic structure calculations employing Density Functional Theory will be carried out to elucidate the ring opening of the epoxide by alkylcarbonate and alkoxide ligands and the chain growth mechanism. Polymerization of lactide will be investigated using inexpensive solid supports and catalytic routes to cyclic esters are proposed wherein complexation to metal ions may allow chemical amplification of specific rings. With an understanding of mechanisms involving the reactions of M-OR bonds the development of single-site catalysis for the

  1. The metal site as a template for the metalloprotein structure formation.

    PubMed

    Liu, Changlin; Xu, Huibi

    2002-01-01

    Achieving a thorough explanation of the behavior of metal sites in the formation of native metalloprotein structures is an exciting challenge in the biochemistry of metallobiomacromolecules. This study presents a personal insight into the subject. It is proposed that a metal center and its exogenous ligand compose a template. A template may impose a clear stereochemical preference on the loose peptide chains, and organize them into natural stereospecificity via the metal-ligand interaction, a long-range and strong interaction. Therefore, the stable peptide conformation induced by the template effect surrounding a template polyhedron could be called a template-mediated structural motif (TMSM).

  2. Synthesis and characterization of a series of rubidium alkoxides and rubidium-titanium double alkoxides.

    PubMed

    Bunge, Scott D; Boyle, Timothy J; Pratt III, Harry D; Alam, Todd M; Rodriguez, Mark A

    2004-09-20

    This report investigates the structural aspects of the products isolated from the reactions of a series of titanium alkoxides [[Ti(OR)4]n n = 2, OR = OCH2C(CH3)3 (ONep) (1); n = 1, OC6H3(CH3)2-2,6 (DMP) (2)] with rubidium alkoxides [[Rb(OR)]infinity where OR = (ONep) (3), (DMP) (4), and OC6H3(CH(CH3)2)2-2,6 (DIP) (5)]. The resultant double alkoxides were determined by single crystal X-ray diffraction to be [Rb(mu-ONep)4(py)Ti(ONep)]2 (6), [Rb(mu-DMP)Ti(DMP)4]infinity (7), and [Rb(mu-DMP)2(mu-ONep)2Ti(ONep)]infinity (8). Compound 1 is the previously reported dinculear species with trigonal bipyramidal Ti metal centers whereas compound 2 is a monomer with a tetrahedral Ti center. Suitable X-ray quality crystals of 3 were not isolated. Compounds 4 and 5 demonstrate extended polymeric networks with Rb coordination ranging from two to five utilizing terminal mu- and mu3-OR ligands and pi-interactions of neighboring OAr ligands. The double alkoxide 6 revealed a simple tetranuclear structure with mu-ONep acting as the bridge, terminal ONep ligands on the Ti, and one terminal py on the Rb. For 7 and 8, the pi-interaction facilitated the formation of extended polymeric systems. All complexes were further characterized by FT-IR and multinuclear NMR spectroscopy.

  3. Mechanistic studies aimed at the development of single site metal alkoxide catalysts for the production of polyoxygenates from renewable resources.

    SciTech Connect

    Chisholm, Malcolm H.

    2015-12-15

    The work proposed herein follows on directly from the existing 3 year grant and the request for funding is for 12 months to allow completion of this work and graduation of current students supported by DOE. The three primary projects are as follows. 1.) A comparative study of the reactivity of LMg(OR) (solvent), where L= a β-diiminate or pyrromethene ligand, in the ring-opening of cyclic esters. 2.) The homopolymerization of expoxides, particularly propylene oxide and styrene oxide, and their copolymerizations with carbon dioxide or organic anhydrides to yield polycarbonates or polyesters, respectively. 3.) The development of well-defined bismuth (III) complexes for ring-opening polymerizations that are tolerant of both air and water. In each of these topics special emphasis is placed on developing a detailed mechanistic understanding of the ring-opening event and how this is modified by the employment of specific metal and ligand combinations. This document also provides a report on findings of the past grant period that are not yet in the public domain/published and shows how the proposed work will bring the original project to conclusion.

  4. Template-directed synthesis of oligoguanylic acids - Metal ion catalysis

    NASA Technical Reports Server (NTRS)

    Bridson, P. K.; Fakhrai, H.; Lohrmann, R.; Orgel, L. E.; Van Roode, M.

    1981-01-01

    The effects of Zn(2+), Pb(2+) and other metal ions on the efficiency and stereo-selectivity of the template-directed oligomerization of guanosine 5'-phosphorimidazolide are investigated. Reactions were run in the presence of a polyC template in a 2,6-lutidine buffer, and products analyzed by high-performance liquid chromatography on an RPC-5 column. The presence of the Pb(2+) ion is found to lead to the formation of 2'-5' linked oligomers up to the 40-mer, while Zn(2+) favors the formation of predominantly 3'-5' linked oligomers up to the 35-mer. When amounts of uracil, cytidine or adenosine 5'-phosphorimidazole equal to those of the guanosine derivative are included in the reaction mixture, the incorrect base is incorporated into the oligomer about 10% of the time with a Pb(2+) catalyst, but less than 0.5% of the time with Zn(2+). The Sn(2+), Sb(3+) and Bi(3+) ions are also found to promote the formation of 2'-5' oligomers, although not as effectively as Pb(2+), while no metal ions other than Zn(2+) promote the formation of the 3'-5' oligomers. The results may be important for the understanding of the evolution of nucleic acid replication in the absence of enzymes.

  5. Structure of fluorescent metal clusters on a DNA template.

    NASA Astrophysics Data System (ADS)

    Vdovichev, A. A.; Sych, T. S.; Reveguk, Z. V.; Smirnova, A. A.; Maksimov, D. A.; Ramazanov, R. R.; Kononov, A. I.

    2016-08-01

    Luminescent metal clusters are a subject of growing interest in recent years due to their bright emission from visible to near infrared range. Detailed structure of the fluorescent complexes of Ag and other metal clusters with ligands still remains a challenging task. In this joint experimental and theoretical study we synthesized Ag-DNA complexes on a DNA oligonucleotide emitting in violet- green spectral range. The structure of DNA template was determined by means of various spectral measurements (CD, MS, XPS). Comparison of the experimental fluorescent excitation spectra and calculated absorption spectra for different QM/MM optimized structures allowed us to determine the detailed structure of the green cluster containing three silver atoms in the stem of the DNA hairpin structure stabilized by cytosine-Ag+-cytosine bonds.

  6. Fabrication and characterization of metal-semiconductor-metal nanorod using template synthesis

    SciTech Connect

    Kim, Kyohyeok; Kwon, Namyong; Hong, Junki; Chung, Ilsub

    2009-07-15

    The authors attempted to fabricate and characterize one dimensional metal-semiconductor-metal (MSM) nanorod using a template. Cadmium selenide (CdSe) and polypyrrole (Ppy) were chosen as n-type and p-type semiconductor materials, respectively, whereas Au was chosen as a metal electrode. The fabrication of the nanorod was achieved by ''template synthesis'' method using polycarbonate membrane. The structure of the fabricated nanorod was analyzed using scanning electron microscopy and energy dispersive spectroscopy. In addition, the electrical properties of MSM nanorods were characterized using scanning probe microscopy (Seiko Instruments, SPA 300 HV) by probing with a conductive cantilever. I-V characteristics as a function of the temperature give the activation energy, as well as the barrier height of a metal-semiconductor contact, which is useful to understand the conduction mechanism of MSM nanorods.

  7. Metal-organic framework templated inorganic sorbents for rapid and efficient extraction of heavy metals.

    PubMed

    Abney, C W; Gilhula, J C; Lu, K; Lin, W

    2014-12-17

    An innovative wet-treatment with Na2 S transforms two indium metal-organic frameworks (MOFs) into a series of porous inorganic sorbents. These MOF-templated materials display remarkable affinity for heavy metals with saturation occurring in less than 1 h. The saturation capacity for Hg(II) exceeds 2 g g(-1) , more than doubling the best thiol-functionalized sorbents in the literature.

  8. Silica needle template fabrication of metal hollow microneedle arrays

    NASA Astrophysics Data System (ADS)

    Zhu, M. W.; Li, H. W.; Chen, X. L.; Tang, Y. F.; Lu, M. H.; Chen, Y. F.

    2009-11-01

    Drug delivery through hollow microneedle (HMN) arrays has now been recognized as one of the most promising techniques because it minimizes the shortcomings of the traditional drug delivery methods and has many exciting advantages—pain free and tunable release rates, for example. However, this drug delivery method has been hindered greatly from mass clinical application because of the high fabrication cost of HMN arrays. Hence, we developed a simple and cost-effective procedure using silica needles as templates to massively fabricate HMN arrays by using popular materials and industrially applicable processes of micro- imprint, hot embossing, electroplating and polishing. Metal HMN arrays with high quality are prepared with great flexibility with tunable parameters of area, length of needle, size of hollow and array dimension. This efficient and cost-effective fabrication method can also be applied to other applications after minor alterations, such as preparation of optic, acoustic and solar harvesting materials and devices.

  9. Tridentate ligated heteronuclear tin(II) alkoxides for use as base catalysts

    DOEpatents

    Boyle, Timothy J.

    2001-01-01

    Tin alkoxide compounds are provided with accessible electrons. The tin alkoxide compound have the general formula (THME).sub.2 Sn.sub.3 (M(L).sub.x).sub.y, where THME is (O--CH.sub.2).sub.3 C(CH.sub.3), M is a metal atom selected from Sn and Ti, L is an organic/inorganic ligand selected from an alkoxide, a phenoxide or an amide, x is selected from 2 and 4 and y is selected from 0 and 1. These compounds have applicability as base catalysts in reactions and in metal-organic chemical vapor depositions processes.

  10. Preparation of Mesoporous Silica Templated Metal Nanowire Films on Foamed Nickel Substrates

    SciTech Connect

    Campbell, Roger; Kenik, Edward A; Bakker, Martin; Havrilla, George; Montoya, Velma; Shamsuzzoha, Mohammed

    2006-01-01

    A method has been developed for the formation of high surface area nanowire films on planar and three-dimensional metal electrodes. These nanowire films are formed via electrodeposition into a mesoporous silica film. The mesoporous silica films are formed by a sol-gel process using Pluronic tri-block copolymers to template mesopore formation on both planar and three-dimensional metal electrodes. Surface area increases of up to 120-fold have been observed in electrodes containing a templated film when compared to the same types of electrodes without the templated film.

  11. Nanofabrication of highly ordered, tunable metallic mesostructures via quasi-hard-templating of lyotropic liquid crystals

    PubMed Central

    Zhang, Xinyi; Lu, Wei; Dai, Jiyan; Bourgeois, Laure; Yao, Jianfeng; Wang, Huanting; Friend, James R.; Zhao, Dongyuan; MacFarlane, Douglas R.

    2014-01-01

    The synthesis of metal frameworks perforated with nanotunnels is a challenge because metals have high surface energies that favor low surface area structures; traditional liquid-crystal templating techniques cannot achieve the synthetic control required. We report a synthetic strategy to fabricate metal nanomaterials with highly ordered, tunable mesostructures in confined systems based on a new quasi-hard-templating liquid-crystals mechanism. The resulting platinum nanowires exhibit long range two-dimensional hexagonally ordered mesopore structures. In addition, single crystalline hexagonal mesoporous platinum nanowires with dominant {110} facets have been synthesized. Finally, we demonstrate that the mesostructures of metal nanomaterials can be tuned from hexagonal to lamellar mesostructures. PMID:25502015

  12. Rational Design of Biomolecular Templates for Synthesizing Multifunctional Noble Metal Nanoclusters toward Personalized Theranostic Applications.

    PubMed

    Yu, Yong; Mok, Beverly Y L; Loh, Xian Jun; Tan, Yen Nee

    2016-08-01

    Biomolecule-templated or biotemplated metal nanoclusters (NCs) are ultrasmall (<2 nm) metal (Au, Ag) particles stabilized by a certain type of biomolecular template (e.g., peptides, proteins, and DNA). Due to their unique physiochemical properties, biotemplated metal NCs have been widely used in sensing, imaging, delivery and therapy. The overwhelming applications in these individual areas imply the great promise of harnessing biotemplated metal NCs in more advanced biomedical aspects such as theranostics. Although applications of biotemplated metal NCs as theranostic agents are trending, the rational design of biomolecular templates suitable for the synthesis of multifunctional metal NCs for theranostics is comparatively underexplored. This progress report first identifies the essential attributes of biotemplated metal NCs for theranostics by reviewing the state-of-art applications in each of the four modalities of theranostics, namely sensing, imaging, delivery and therapy. To achieve high efficacy in these modalities, we elucidate the design principles underlying the use of biomolecules (proteins, peptides and nucleic acids) to control the NC size, emission color and surface chemistries for post-functionalization of therapeutic moieties. We then propose a unified strategy to engineer biomolecular templates that combine all these modalities to produce multifunctional biotemplated metal NCs that can serve as the next-generation personalized theranostic agents. PMID:27377035

  13. Rational Design of Biomolecular Templates for Synthesizing Multifunctional Noble Metal Nanoclusters toward Personalized Theranostic Applications.

    PubMed

    Yu, Yong; Mok, Beverly Y L; Loh, Xian Jun; Tan, Yen Nee

    2016-08-01

    Biomolecule-templated or biotemplated metal nanoclusters (NCs) are ultrasmall (<2 nm) metal (Au, Ag) particles stabilized by a certain type of biomolecular template (e.g., peptides, proteins, and DNA). Due to their unique physiochemical properties, biotemplated metal NCs have been widely used in sensing, imaging, delivery and therapy. The overwhelming applications in these individual areas imply the great promise of harnessing biotemplated metal NCs in more advanced biomedical aspects such as theranostics. Although applications of biotemplated metal NCs as theranostic agents are trending, the rational design of biomolecular templates suitable for the synthesis of multifunctional metal NCs for theranostics is comparatively underexplored. This progress report first identifies the essential attributes of biotemplated metal NCs for theranostics by reviewing the state-of-art applications in each of the four modalities of theranostics, namely sensing, imaging, delivery and therapy. To achieve high efficacy in these modalities, we elucidate the design principles underlying the use of biomolecules (proteins, peptides and nucleic acids) to control the NC size, emission color and surface chemistries for post-functionalization of therapeutic moieties. We then propose a unified strategy to engineer biomolecular templates that combine all these modalities to produce multifunctional biotemplated metal NCs that can serve as the next-generation personalized theranostic agents.

  14. Fabrication of Smooth Patterned Structures of Refractory Metals, Semiconductors, and Oxides via Template Stripping

    PubMed Central

    2013-01-01

    The template-stripping method can yield smooth patterned films without surface contamination. However, the process is typically limited to coinage metals such as silver and gold because other materials cannot be readily stripped from silicon templates due to strong adhesion. Herein, we report a more general template-stripping method that is applicable to a larger variety of materials, including refractory metals, semiconductors, and oxides. To address the adhesion issue, we introduce a thin gold layer between the template and the deposited materials. After peeling off the combined film from the template, the gold layer can be selectively removed via wet etching to reveal a smooth patterned structure of the desired material. Further, we demonstrate template-stripped multilayer structures that have potential applications for photovoltaics and solar absorbers. An entire patterned device, which can include a transparent conductor, semiconductor absorber, and back contact, can be fabricated. Since our approach can also produce many copies of the patterned structure with high fidelity by reusing the template, a low-cost and high-throughput process in micro- and nanofabrication is provided that is useful for electronics, plasmonics, and nanophotonics. PMID:24001174

  15. Fabrication of smooth patterned structures of refractory metals, semiconductors, and oxides via template stripping.

    PubMed

    Park, Jong Hyuk; Nagpal, Prashant; McPeak, Kevin M; Lindquist, Nathan C; Oh, Sang-Hyun; Norris, David J

    2013-10-01

    The template-stripping method can yield smooth patterned films without surface contamination. However, the process is typically limited to coinage metals such as silver and gold because other materials cannot be readily stripped from silicon templates due to strong adhesion. Herein, we report a more general template-stripping method that is applicable to a larger variety of materials, including refractory metals, semiconductors, and oxides. To address the adhesion issue, we introduce a thin gold layer between the template and the deposited materials. After peeling off the combined film from the template, the gold layer can be selectively removed via wet etching to reveal a smooth patterned structure of the desired material. Further, we demonstrate template-stripped multilayer structures that have potential applications for photovoltaics and solar absorbers. An entire patterned device, which can include a transparent conductor, semiconductor absorber, and back contact, can be fabricated. Since our approach can also produce many copies of the patterned structure with high fidelity by reusing the template, a low-cost and high-throughput process in micro- and nanofabrication is provided that is useful for electronics, plasmonics, and nanophotonics.

  16. Determination of rare earth elements in seawater by inductively coupled plasma mass spectrometry with on-line column pre-concentration using 8-quinolinole-immobilized fluorinated metal alkoxide glass

    NASA Astrophysics Data System (ADS)

    Kajiya, Tasuku; Aihara, Masato; Hirata, Shizuko

    2004-04-01

    The on-line column pre-concentration technique with inductively coupled plasma mass spectrometry (ICP-MS) has been developed using micro-column of 8-quinolinole-immobilized fluorinated metal alkoxide glass (MAF-8HQ). The aim of method was to determine rare earth elements (REEs) (Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) in seawater. A 6.4 ml of seawater sample was passed through the column for 2 min, after washing the column with ultrapure water, the adsorbed REEs were subsequently eluted into the plasma with 1.4 M nitric acid. Sample pH, sampling and eluting flow rates and acidity of eluent were optimized. Detection limits (3 σ) based on three times standard deviations of water by 8 replicates were in the range from 0.11 pg ml -1 for Y to 0.30 pg ml -1 for Tb, and the precisions by a 10 pg ml -1 REEs standard solution ( n=8) were in the range from 4.7% for Tm to 8.7% for Tb and Yb. Analysis of one sample could be processed in 7 min. The proposed method was verified by determination of REEs in the two certified reference materials (CRMs) of seawater, CASS-4 and NASS-5, and the method was also applied to determine REEs in the costal seawater of Hiroshima Bay, the Seto Inland Sea, Japan.

  17. Two-Dimensional Porous Micro/Nano Metal Oxides Templated by Graphene Oxide.

    PubMed

    Cao, Hailiang; Zhou, Xufeng; Zheng, Chao; Liu, Zhaoping

    2015-06-10

    Novel two-dimensional (2D) porous metal oxides with micro-/nanoarchitecture have been successfully fabricated using graphene oxide (GO) as a typical sacrificial template. GO as a 2D template ensures that the growth and fusion of metal oxides nanoparticles is restricted in the 2D plane. A series of metal oxides (NiO, Fe2O3, Co3O4, Mn2O3, and NiFe2O4) with similar nanostructure were investigated using this simple method. Some of these special nanostructured materials, such as NiO, when being used as anode for lithium-ion batteries, can exhibit high specific capacity, good rate performance, and cycling stability. Importantly, this strategy of creating a 2D porous micro/nano architecture can be easily extended to controllably synthesize other binary/polynary metal oxides nanostructures for lithium-ion batteries or other applications.

  18. Formation of 3D graphene foams on soft templated metal monoliths.

    PubMed

    Tynan, Michael K; Johnson, David W; Dobson, Ben P; Coleman, Karl S

    2016-07-21

    Graphene foams are leading contenders as frameworks for polymer thermosets, filtration/pollution control and for use as an electrode material in energy storage devices, taking advantage of graphene's high electrical conductivity and the porous structure of the foam. Here we demonstrate a simple synthesis of a macroporous 3D graphene material templated from a dextran/metal salt gel, where the metal was cobalt, nickel, copper, and iron. The gel was annealed to form a metal oxide foam prior to a methane chemical vapour deposition (CVD). Cobalt metal gels were shown to afford the highest quality material as determined by electron microscopy (SEM and TEM) and Raman spectroscopy.

  19. Templated fabrication of periodic arrays of metallic and silicon nanorings with complex nanostructures

    NASA Astrophysics Data System (ADS)

    Liu, Xuefeng; Gozubenli, Numan; Choi, Baeck; Jiang, Peng; Meagher, Timothy; Jiang, Bin

    2015-02-01

    Here we report a scalable colloidal templating approach for fabricating periodic arrays of metallic and silicon nanorings with complex nanostructures. Non-close-packed monolayer silica colloidal crystal prepared by a simple spin-coating technology is first used as template for making periodic arrays of mushroom-like composite nanostructures consisting of silica spherical caps and polymer stems. Subsequent metal sputtering and reactive ion etching lead to the formation of ordered asymmetric nickel nanorings which can be further utilized as etching masks for patterning periodic arrays of symmetric silicon nanorings. Moreover, periodic arrays of metallic and silicon concentric double nanorings can be fabricated by using the asymmetric nickel nanorings as templates. We have also demonstrated that gold concentric double nanorings show strong surface-enhanced Raman scattering (SERS) with a SERS enhancement factor of ˜9.5 × 107 from adsorbed benzenethiol molecules. The SERS enhancement and the electric field amplitude distribution surrounding gold concentric double nanorings have been calculated by using finite element electromagnetic modeling. This new colloidal templating technique is compatible with standard microfabrication and enables wafer-scale production of a variety of periodic nanorings with hierarchical structures that could find important technological applications in plasmonic and magnetic devices.

  20. Electrical property measurements of metallized flagella-templated silica nanotube networks

    NASA Astrophysics Data System (ADS)

    Jo, Wonjin; Darmawan, Marten; Kim, Jihoon; Ahn, Chi Won; Byun, Doyoung; Baik, Seung Hyun; Kim, Min Jun

    2013-04-01

    We present an improvement in the electrical properties of silica nanotubes by coating metal nanoparticles on their surfaces. The silica nanotubes are formed from bacterial flagella bio-templates having a tubular structure. Successive depositions of metal nanoparticles on the silica nanotubes are performed through easily functionalized silica surfaces. The results show uniform metal nanoparticle sizes and a high surface area coverage. By incorporating gold, palladium and iron oxide nanoparticles, the metallized silica nanotubes gain electrical properties with the potential to create unique nanoelectronic materials. In this study, the metallized silica nanotubes with network structures are aligned and their electrical behaviors are investigated in both dry and wet conditions. The metallized silica nanotubes are found to be electrically conductive along the network structures. The current-voltage characteristics show remarkably improved electrical conductivities depending on the type of metal nanoparticle loading and nanotube network concentration.

  1. Electrical property measurements of metallized flagella-templated silica nanotube networks.

    PubMed

    Jo, Wonjin; Darmawan, Marten; Kim, Jihoon; Ahn, Chi Won; Byun, Doyoung; Baik, Seung Hyun; Kim, Min Jun

    2013-04-01

    We present an improvement in the electrical properties of silica nanotubes by coating metal nanoparticles on their surfaces. The silica nanotubes are formed from bacterial flagella bio-templates having a tubular structure. Successive depositions of metal nanoparticles on the silica nanotubes are performed through easily functionalized silica surfaces. The results show uniform metal nanoparticle sizes and a high surface area coverage. By incorporating gold, palladium and iron oxide nanoparticles, the metallized silica nanotubes gain electrical properties with the potential to create unique nanoelectronic materials. In this study, the metallized silica nanotubes with network structures are aligned and their electrical behaviors are investigated in both dry and wet conditions. The metallized silica nanotubes are found to be electrically conductive along the network structures. The current-voltage characteristics show remarkably improved electrical conductivities depending on the type of metal nanoparticle loading and nanotube network concentration.

  2. Peptide template effects on the synthesis and reactivity of metal nanoparticle networks

    NASA Astrophysics Data System (ADS)

    Bhandari, Rohit

    A bio-templated approach for the synthesis of multiple inorganic materials has been presented that correlates with the role of a 3-dimensional peptide template in controlling the overall reactivity of the fabricated materials for a variety of chemical reactions. The role of self-assembling R5 peptide for the formation of metallic nanoparticles including Pd, Au and Pt has been described. The materials were fully characterized using UV-vis spectroscopy, dynamic light scattering analysis, transmission electron microscopy and powder-X ray diffraction analysis. Also, the materials were employed as efficient catalysts for the Stille coupling reaction, 4-nitrophenol reduction as well as olefin hydrogenation reactions. These results are important as these template-based materials could potentially serve as candidates for a variety of applications ranging from bio- sensing tocatalysis to energy production.

  3. Formation of 3D graphene foams on soft templated metal monoliths

    NASA Astrophysics Data System (ADS)

    Tynan, Michael K.; Johnson, David W.; Dobson, Ben P.; Coleman, Karl S.

    2016-07-01

    Graphene foams are leading contenders as frameworks for polymer thermosets, filtration/pollution control and for use as an electrode material in energy storage devices, taking advantage of graphene's high electrical conductivity and the porous structure of the foam. Here we demonstrate a simple synthesis of a macroporous 3D graphene material templated from a dextran/metal salt gel, where the metal was cobalt, nickel, copper, and iron. The gel was annealed to form a metal oxide foam prior to a methane chemical vapour deposition (CVD). Cobalt metal gels were shown to afford the highest quality material as determined by electron microscopy (SEM and TEM) and Raman spectroscopy.Graphene foams are leading contenders as frameworks for polymer thermosets, filtration/pollution control and for use as an electrode material in energy storage devices, taking advantage of graphene's high electrical conductivity and the porous structure of the foam. Here we demonstrate a simple synthesis of a macroporous 3D graphene material templated from a dextran/metal salt gel, where the metal was cobalt, nickel, copper, and iron. The gel was annealed to form a metal oxide foam prior to a methane chemical vapour deposition (CVD). Cobalt metal gels were shown to afford the highest quality material as determined by electron microscopy (SEM and TEM) and Raman spectroscopy. Electronic supplementary information (ESI) available: Raman, EDX, PXRD, TGA, electrical conductivity data and SEM. See DOI: 10.1039/c6nr02455f

  4. Apoferritin Templated Synthesis of Metal Phosphate Nanoparticle Labels for Electrochemical Immunoassay

    SciTech Connect

    Liu, Guodong; Wu, Hong; Wang, Jun; Lin, Yuehe

    2006-08-29

    W have introduced template-synthesized metal phosphate nanoparticle labels for electrochemical immunoassay. Such use of an apoferritin template offers a simple and convenient route to prepare metallic nanoparticle labels for electrochemical immunoassays and avoid the complicated and time-consuming nanoparticle synthesis process (QD synthesis). Releasing metal ions from metal phosphate in an acetate buffer (pH 4.6) eliminates the harsh condition in the traditional metallic nanoparticle dissolution (e.g., strong acid dissolution of QDs and gold nanoparticles). This method is ultrasensitive and its DL is low to 77fM. The simultaneous detection of multiple protein targets is easily performed by using different metal phosphate nanoparticle labels (cadmium phosphate and lead phosphate). This approach can be extended to prepare multiple metal (such as zinc, lead, cadmium, copper, indium, gold, silver) phosphate nanoparticle labels or hybrid metal (bimetallic or trimetallic with predetermined ratios) phosphate nanoparticle labels for a multiplex electrochemical immunoassay. The new nanoparticle labels could be applicable to other electrochemical bioassays, such as DNA, and is thus expected to lead to wide applications for protein diagnostics and for bioanalysis in general.

  5. Use of carbonaceous polysaccharide microspheres as templates for fabricating metal oxide hollow spheres.

    PubMed

    Sun, Xiaoming; Liu, Junfeng; Li, Yadong

    2006-02-20

    A general method for the synthesis of metal oxide hollow spheres has been developed by using carbonaceous polysaccharide microspheres prepared from saccharide solution as templates. Hollow spheres of a series of metal oxides (SnO2, Al2O3, Ga2O3, CoO, NiO, Mn3O4, Cr2O3, La2O3, Y2O3, Lu2O3, CeO2, TiO2, and ZrO2) have been prepared in this way. The method involves the initial absorption of metal ions from solution into the functional surface layer of carbonaceous saccharide microspheres; these are then densified and cross-linked in a subsequent calcination and oxidation procedure to form metal oxide hollow spheres. Metal salts are used as starting materials, which widens the accessible field of metal oxide hollow spheres. The carbonaceous colloids used as templates have integral and uniform surface functional layers, which makes surface modification unnecessary and ensures homogeneity of the shell. Macroporous films or cheese-like nanostructures of oxides can also be prepared by slightly modified procedures. XRD, TEM, HRTEM, and SAED have been used to characterize the structures. In a preliminary study on the gas sensitivity of SnO2 hollow spheres, considerably reduced "recovery times" were noted, exemplifying the distinct properties imparted by the hollow structure. These hollow or porous nanostructures have the potential for diverse applications, such as in gas sensitivity or catalysis, or as advanced ceramic materials.

  6. Use of carbonaceous polysaccharide microspheres as templates for fabricating metal oxide hollow spheres.

    PubMed

    Sun, Xiaoming; Liu, Junfeng; Li, Yadong

    2006-02-20

    A general method for the synthesis of metal oxide hollow spheres has been developed by using carbonaceous polysaccharide microspheres prepared from saccharide solution as templates. Hollow spheres of a series of metal oxides (SnO2, Al2O3, Ga2O3, CoO, NiO, Mn3O4, Cr2O3, La2O3, Y2O3, Lu2O3, CeO2, TiO2, and ZrO2) have been prepared in this way. The method involves the initial absorption of metal ions from solution into the functional surface layer of carbonaceous saccharide microspheres; these are then densified and cross-linked in a subsequent calcination and oxidation procedure to form metal oxide hollow spheres. Metal salts are used as starting materials, which widens the accessible field of metal oxide hollow spheres. The carbonaceous colloids used as templates have integral and uniform surface functional layers, which makes surface modification unnecessary and ensures homogeneity of the shell. Macroporous films or cheese-like nanostructures of oxides can also be prepared by slightly modified procedures. XRD, TEM, HRTEM, and SAED have been used to characterize the structures. In a preliminary study on the gas sensitivity of SnO2 hollow spheres, considerably reduced "recovery times" were noted, exemplifying the distinct properties imparted by the hollow structure. These hollow or porous nanostructures have the potential for diverse applications, such as in gas sensitivity or catalysis, or as advanced ceramic materials. PMID:16374888

  7. Template-directed assembly of metal-chalcogenide nanocrystals into ordered mesoporous networks.

    SciTech Connect

    Vamvasakis, Ioannis; Subrahmanyam, Kota S.; Kanatzidis, Mercouri G.; Armatas, Gerasimos S.

    2015-04-01

    Although great progress in the synthesis of porous networks of metal and metal oxide nanoparticles with highly accessible pore surface and ordered mesoscale pores has been achieved, synthesis of assembled 3D mesostructures of metal-chalcogenide nanocrystals is still challenging. In this work we demonstrate that ordered mesoporous networks, which comprise well-defined interconnected metal sulfide nanocrystals, can be prepared through a polymer-templated oxidative polymerization process. The resulting self-assembled mesostructures that were obtained after solvent extraction of the polymer template impart the unique combination of light-emitting metal chalcogenide nanocrystals, three-dimensional open-pore structure, high surface area, and uniform pores. We show that the pore surface of these materials is active and accessible to incoming molecules, exhibiting high photocatalytic activity and stability, for instance, in oxidation of 1-phenylethanol into acetophenone. We demonstrate through appropriate selection of the synthetic components that this method is general to prepare ordered mesoporous materials from metal chalcogenide nanocrystals with various sizes and compositions.

  8. High aspect ratio 10-nm-scale nanoaperture arrays with template-guided metal dewetting

    PubMed Central

    Wang, Ying Min; Lu, Liangxing; Srinivasan, Bharathi Madurai; Asbahi, Mohamed; Zhang, Yong Wei; Yang, Joel K. W.

    2015-01-01

    We introduce an approach to fabricate ordered arrays of 10-nm-scale silica-filled apertures in a metal film without etching or liftoff. Using low temperature (<400°C) thermal dewetting of metal films guided by nano-patterned templates, apertures with aspect ratios up to 5:1 are demonstrated. Apertures form spontaneously during the thermal process without need for further processing. Although the phenomenon of dewetting has been well studied, this is the first demonstration of its use in the fabrication of nanoapertures in a spatially controllable manner. In particular, the achievement of 10-nm length-scale patterning at high aspect ratio with thermal dewetting is unprecedented. By varying the nanotemplate design, we show its strong influence over the positions and sizes of the nanoapertures. In addition, we construct a three-dimensional phase field model of metal dewetting on nano-patterned substrates. The simulation data obtained closely corroborates our experimental results and reveals new insights to template dewetting at the nanoscale. Taken together, this fabrication method and simulation model form a complete toolbox for 10-nm-scale patterning using template-guided dewetting that could be extended to a wide range of material systems and geometries. PMID:25858792

  9. Self-aligned grating couplers on template-stripped metal pyramids via nanostencil lithography

    NASA Astrophysics Data System (ADS)

    Klemme, Daniel J.; Johnson, Timothy W.; Mohr, Daniel A.; Oh, Sang-Hyun

    2016-05-01

    We combine nanostencil lithography and template stripping to create self-aligned patterns about the apex of ultrasmooth metal pyramids with high throughput. Three-dimensional patterns such as spiral and asymmetric linear gratings, which can couple incident light into a hot spot at the tip, are presented as examples of this fabrication method. Computer simulations demonstrate that spiral and linear diffraction grating patterns are both effective at coupling light to the tip. The self-aligned stencil lithography technique can be useful for integrating plasmonic couplers with sharp metallic tips for applications such as near-field optical spectroscopy, tip-based optical trapping, plasmonic sensing, and heat-assisted magnetic recording.

  10. Alkoxide and Aryloxide Derivatives of a (Triamidoamine)uranium Complex.

    PubMed

    Roussel, Paul; Hitchcock, Peter B.; Tinker, Nigel D.; Scott, Peter

    1997-12-01

    The (triamidoamine)uranium chloride complex [{U(NN(3))(&mgr;-Cl)}(2)] [NN(3) = N(CH(2)CH(2)NSiMe(3))(3)] reacts with alkali metal alkoxides and aryloxides to give a range of complexes [U(NN(3))(OR)] (R = Bu(t), t-C(4)F(9), Ph, 2,6-Bu(t)(2)-4-MeC(6)H(2)). Crystallographic investigations (including the molecular structure of the perfluoro-tert-butoxido derivative [U(NN(3))(O-t-C(4)F(9))]), molecular weight determinations, and NMR spectroscopic data are consistent with these molecules being monomeric with a 3-fold symmetric arrangement of the triamidoamine fragment. The three turquoise ate complexes [U(NN(3))(OR)(OR')Li(THF)(n)()] (R, R' = Bu(t) or Ph), are prepared by reaction of the corresponding uranium alkoxides with lithium phenoxide or tert-butoxide. The complex with R = Ph, R' = Bu(t), n = 1 is shown by X-ray crystallography to have a capped trigonal bipyramidal structure. A lithium atom is incorporated into the ligand sphere by coordination to an amido nitrogen and a tert-butoxido oxygen. The mixed alkoxide ate complex [U(NN(3))(OBu(t))(OPh)Li(THF)] gives only [U(NN(3))(OBu(t))] on heating in vacuo. The one-electron oxidation of these ate complexes to the three neutral pentavalent compounds [U(NN(3))(OR)(OR')] (R, R' = Bu(t) or Ph) has been characterized by cyclic voltammetric studies and performed on the chemical scale by reaction with [FeCp(2)][PF(6)].

  11. Size-Reduction Template Stripping of Smooth Curved Metallic Tips for Adiabatic Nanofocusing of Surface Plasmons.

    PubMed

    Johnson, Timothy W; Klemme, Daniel J; Oh, Sang-Hyun

    2016-06-01

    We present a new technique to engineer metallic interfaces to produce sharp tips with smooth curved surfaces and variable tip angles, as well as ridges with arbitrary contour shapes, all of which can be integrated with grating couplers for applications in plasmonics and nanophotonics. We combine template stripping, a nanofabrication scheme, with atomic layer deposition (ALD) to produce the ultrasharp nanoscale tips and wedges using only conventional photolithography. Conformal ALD coating of insulators over silicon trench molds of various shapes reduces their widths to make nanoscale features without high-resolution lithography. Along with a metal deposition and template stripping, this size-reduction scheme can mass-produce narrow and ultrasharp (<10 nm radius of curvature) metallic wedges and tips over an entire 4 in. wafer. This size-reduction scheme can create metallic tips out of arbitrary trench patterns that have smooth curved surfaces to facilitate efficient adiabatic nanofocusing which will benefit applications in near-field optical spectroscopy, plasmonic waveguides, particle trapping, hot-electron plasmonics, and nonlinear optics. PMID:27156522

  12. Alcohol-free alkoxide process for containing nuclear waste

    DOEpatents

    Pope, James M.; Lahoda, Edward J.

    1984-01-01

    Disclosed is a method of containing nuclear waste. A composition is first prepared of about 25 to about 80%, calculated as SiO.sub.2, of a partially hydrolyzed silicon compound, up to about 30%, calculated as metal oxide, of a partially hydrolyzed aluminum or calcium compound, about 5 to about 20%, calculated as metal oxide, of a partially hydrolyzed boron or calcium compound, about 3 to about 25%, calculated as metal oxide, of a partially hydrolyzed sodium, potassium or lithium compound, an alcohol in a weight ratio to hydrolyzed alkoxide of about 1.5 to about 3% and sufficient water to remove at least 99% of the alcohol as an azeotrope. The azeotrope is boiled off and up to about 40%, based on solids in the product, of the nuclear waste, is mixed into the composition. The mixture is evaporated to about 25 to about 45% solids and is melted and cooled.

  13. Fabrication of transition metal-containing nanostructures via polymer templates for a multitude of applications

    NASA Astrophysics Data System (ADS)

    Lu, Jennifer Qing

    Nanostructures such as carbon nanotubes and semiconducting nanowires offer great technological promise due to their remarkable properties. The lack of a rational synthesis method prevents fabricating these nanostructures with desirable and consistent properties at predefined locations for device applications. In this thesis, employing polymer templates, a variety of highly ordered catalytically active transition metal nanostructures, ranging from single metallic nanoparticles of Fe, Co, Ni, Au and bimetallic nanoparticles of Ni/Fe and Co/Mo to Fe-rich silicon oxide nanodomains with uniform and tunable size and spacing have been successfully synthesized. These nanostructures have been demonstrated to be excellent catalyst systems for the synthesis of carbon nanotube and silicon nanowire. High quality, small diameter carbon nanotubes and nanowires with narrow size distribution have been successfully attained. Because these catalytically active nanostructures are uniformly distributed and do not agglomerate at the growth temperatures, uniform, high density and high quality carbon nanotube mats have been obtained. Since this polymer template approach is fully compatible with conventional top-down photolithography, lithographically selective growth of carbon nanotubes on a surface or suspended carbon nanotubes across trenches have been produced by using existing semiconductor processing. We have also shown the feasibility of producing carbon nanotubes and silicon nanowires at predefined locations on a wafer format and established a wafer-level carbon nanotube based device fabrication process. The ability of the polymer template approach to control catalyst systems at the nano-, micro- and macro-scales paves a pathway for commercialization of these 1D nanostructure-enabled devices. Beside producing well-defined, highly ordered discrete catalytically active metal-containing nanostructures by the polymer template approach, Au and Ag nanotextured surfaces have also been

  14. Self-ordering of small-diameter metal nanoparticles by dewetting on hexagonal mesh templates

    NASA Astrophysics Data System (ADS)

    Meshot, Eric R.; Zhao, Zhouzhou; Lu, Wei; Hart, A. John

    2014-08-01

    Arrays of small-diameter nanoparticles with high spatial order are useful for chemical and biological sensors, data storage, synthesis of nanowires and nanotubes, and many other applications. We show that self-ordered metal nanoparticle arrays can be formed by dewetting of thin films on hexagonal mesh substrates made of anodic aluminum oxide (AAO). Upon heating, the metal (Fe) film dewets onto the interstitial sites (i.e., the node points) between pores on the top surface of the AAO. We investigated the particle morphology and dynamics of dewetting using a combination of atomic force microscopy (AFM), grazing-incidence small-angle X-ray scattering (GISAXS), and numerical simulations. Templated metal particles are more monodisperse and have higher local order than those formed by the same dewetting process on flat, nonporous alumina. The degree of order depends on the initial film thickness, and for the optimal thickness tested (nominally 2 nm), we achieved uniform coverage and high order of the particles, comparable to that of the AAO template itself. Computational modeling of dewetting on templates with various pore order and size shows that the order of AAO pores is primarily influential in determining particle position and spacing, while the variance in pore size is less impactful. Potential uses of these ordered nanoparticle arrays on porous materials include plasmonic sensors and spatially controlled catalysts.Arrays of small-diameter nanoparticles with high spatial order are useful for chemical and biological sensors, data storage, synthesis of nanowires and nanotubes, and many other applications. We show that self-ordered metal nanoparticle arrays can be formed by dewetting of thin films on hexagonal mesh substrates made of anodic aluminum oxide (AAO). Upon heating, the metal (Fe) film dewets onto the interstitial sites (i.e., the node points) between pores on the top surface of the AAO. We investigated the particle morphology and dynamics of dewetting using

  15. Fabrication of Porous Matrix Membrane (PMM) Using Metal-Organic Framework as Green Template for Water Treatment

    PubMed Central

    Lee, Jian-Yuan; Tang, Chuyang Y.; Huo, Fengwei

    2014-01-01

    Pressure-driven membranes with high porosity can potentially be fabricated by removing template, such as low water stability metal-organic frameworks (MOFs) or other nanoparticles, in polymeric matrix. We report on the use of benign MOFs as green template to enhance porosity and interconnectivity of the water treatment membranes. Significantly enhanced separation performance was observed which might be attributed to the mass transfer coefficient of the substrate layer increased in ultrafiltration (UF) application. PMID:24435326

  16. Spirulina-templated metal microcoils with controlled helical structures for THz electromagnetic responses.

    PubMed

    Kamata, Kaori; Piao, Zhenzi; Suzuki, Soichiro; Fujimori, Takahiro; Tajiri, Wataru; Nagai, Keiji; Iyoda, Tomokazu; Yamada, Atsushi; Hayakawa, Toshiaki; Ishiwara, Mitsuteru; Horaguchi, Satoshi; Belay, Amha; Tanaka, Takuo; Takano, Keisuke; Hangyo, Masanori

    2014-05-12

    Microstructures in nature are ultrafine and ordered in biological roles, which have attracted material scientists. Spirulina forms three-dimensional helical microstructure, one of remarkable features in nature beyond our current processing technology such as lithography in terms of mass-productivity and structural multiplicity. Spirulina varies its diameter, helical pitch, and/or length against growing environment. This unique helix is suggestive of a tiny electromagnetic coil, if composed of electro-conductive metal, which brought us main concept of this work. Here, we describe the biotemplating process onto Spirulina surface to fabricate metal microcoils. Structural parameters of the microcoil can be controlled by the cultivation conditions of Spirulina template and also purely one-handed microcoil can be fabricated. A microcoil dispersion sheet exhibited optically active response attributed to structural resonance in terahertz-wave region.

  17. Spirulina-Templated Metal Microcoils with Controlled Helical Structures for THz Electromagnetic Responses

    PubMed Central

    Kamata, Kaori; Piao, Zhenzi; Suzuki, Soichiro; Fujimori, Takahiro; Tajiri, Wataru; Nagai, Keiji; Iyoda, Tomokazu; Yamada, Atsushi; Hayakawa, Toshiaki; Ishiwara, Mitsuteru; Horaguchi, Satoshi; Belay, Amha; Tanaka, Takuo; Takano, Keisuke; Hangyo, Masanori

    2014-01-01

    Microstructures in nature are ultrafine and ordered in biological roles, which have attracted material scientists. Spirulina forms three-dimensional helical microstructure, one of remarkable features in nature beyond our current processing technology such as lithography in terms of mass-productivity and structural multiplicity. Spirulina varies its diameter, helical pitch, and/or length against growing environment. This unique helix is suggestive of a tiny electromagnetic coil, if composed of electro-conductive metal, which brought us main concept of this work. Here, we describe the biotemplating process onto Spirulina surface to fabricate metal microcoils. Structural parameters of the microcoil can be controlled by the cultivation conditions of Spirulina template and also purely one-handed microcoil can be fabricated. A microcoil dispersion sheet exhibited optically active response attributed to structural resonance in terahertz-wave region. PMID:24815190

  18. FtsZ Cytoskeletal Filaments as a Template for Metallic Nanowire Fabrication.

    PubMed

    Ostrov, Nili; Fichman, Galit; Adler-Abramovich, Lihi; Gazit, Ehud

    2015-01-01

    Supramolecular protein assemblies can serve as templates for the fabrication of inorganic nanowires due to their morphological reproducibility and innate proclivity to form well-ordered structures. Amongst the variety of naturally occurring nano-scale assemblies, cytoskeletal fibers from diverse biological sources represent a unique family of scaffolds for biomimetics as they efficiently self-assemble in vitro in a controllable manner to form stable filaments. Here, we harness the bacterial FtsZ filament system as a scaffold for protein-based metal nanowires, and further demonstrate the control of wire alignment with the use of an external magnetic field. Due to the ease at which the bacterial FtsZ is overexpressed and purified, as well as the extensive studies of its ultrastructural properties and physiological significance, FtsZ filaments are an ideal substrate for large-scale production and chemical manipulation. Using a biologically compatible electroless metal deposition technique initiated by adsorption of platinum as a surface catalyst, we demonstrate the coating of assembled FtsZ filaments with iron, nickel, gold, and copper to fabricate continuous nanowires with diameters ranging from 10-50 nm. Organic-inorganic hybrid wires were analyzed using high-resolution field-emission-gun transmission and scanning electron microscopy, and confirmed by energy-dispersive elemental analysis. We also achieved alignment of ferrofluid-coated FtsZ filaments using an external magnetic field. Overall, we provide evidence for the robustness of the FtsZ filament system as a molecular scaffold, and offer an efficient, biocompatible procedure for facile bottom-up assembly of metallic wires on biological templates. We believe that bottom-up fabrication methods as reported herein significantly contribute to the expanding toolkit available for the incorporation of biological materials in nano-scale devices for electronic and electromechanical applications.

  19. FtsZ Cytoskeletal Filaments as a Template for Metallic Nanowire Fabrication.

    PubMed

    Ostrov, Nili; Fichman, Galit; Adler-Abramovich, Lihi; Gazit, Ehud

    2015-01-01

    Supramolecular protein assemblies can serve as templates for the fabrication of inorganic nanowires due to their morphological reproducibility and innate proclivity to form well-ordered structures. Amongst the variety of naturally occurring nano-scale assemblies, cytoskeletal fibers from diverse biological sources represent a unique family of scaffolds for biomimetics as they efficiently self-assemble in vitro in a controllable manner to form stable filaments. Here, we harness the bacterial FtsZ filament system as a scaffold for protein-based metal nanowires, and further demonstrate the control of wire alignment with the use of an external magnetic field. Due to the ease at which the bacterial FtsZ is overexpressed and purified, as well as the extensive studies of its ultrastructural properties and physiological significance, FtsZ filaments are an ideal substrate for large-scale production and chemical manipulation. Using a biologically compatible electroless metal deposition technique initiated by adsorption of platinum as a surface catalyst, we demonstrate the coating of assembled FtsZ filaments with iron, nickel, gold, and copper to fabricate continuous nanowires with diameters ranging from 10-50 nm. Organic-inorganic hybrid wires were analyzed using high-resolution field-emission-gun transmission and scanning electron microscopy, and confirmed by energy-dispersive elemental analysis. We also achieved alignment of ferrofluid-coated FtsZ filaments using an external magnetic field. Overall, we provide evidence for the robustness of the FtsZ filament system as a molecular scaffold, and offer an efficient, biocompatible procedure for facile bottom-up assembly of metallic wires on biological templates. We believe that bottom-up fabrication methods as reported herein significantly contribute to the expanding toolkit available for the incorporation of biological materials in nano-scale devices for electronic and electromechanical applications. PMID:26328401

  20. Synthesis, structure and characterization of five new organically templated metal sulfates with 2-aminopyridinium.

    PubMed

    Bednarchuk, Tamara J; Kinzhybalo, Vasyl; Pietraszko, Adam

    2016-05-01

    The chemistry of organically templated metal sulfates has attracted interest from the materials science community and the development of synthetic strategies for the preparation of organic-inorganic hybrid materials with novel structures and special properties is of current interest. Sulfur-oxygen-metal linkages provide the possibility of using sulfate tetrahedra as building units to form new solid-state materials. A series of novel organically templated metal sulfates of 2-aminopyridinium (2ap) with aluminium(III), cobalt(II), magnesium(II), nickel(II) and zinc(II) were obtained from the respective aqueous solutions and studied by single-crystal X-ray diffraction. The compounds crystallize in centrosymmetric triclinic unit cells in three structure types: type 1 for 2-aminopyridinium hexaaquaaluminium(III) bis(sulfate) tetrahydrate, (C5H7N2)[Al(H2O)6](SO4)2·4H2O, (I); type 2 for bis(2-aminopyridinium) tris[hexaaquacobalt(II)] tetrakis(sulfate) dihydrate, (C5H7N2)2[Co(H2O)6]3(SO4)4·2H2O, (II), and bis(2-aminopyridinium) tris[hexaaquamagnesium(II)] tetrakis(sulfate) dihydrate, (C5H7N2)2[Mg(H2O)6]3(SO4)4·2H2O, (III); and type 3 for bis(2-aminopyridinium) hexaaquanickel(II) bis(sulfate), (C5H7N2)2[Ni(H2O)6](SO4)2, (IV), and bis(2-aminopyridinium) hexaaquazinc(II) bis(sulfate), (C5H7N2)2[Zn(H2O)6](SO4)2, (V). The templating role of the 2ap cation in all of the reported crystalline substances is governed by the formation of characteristic charge-assisted hydrogen-bonded pairs with sulfate anions and the presence of π-π interactions between the cations. Additionally, both coordinated and uncoordinated water molecules are involved in hydrogen-bond formation. As a consequence, extensive three-dimensional hydrogen-bonding patterns are formed in the reported crystal structures. PMID:27146574

  1. Metallic Nanostructures Based on Self-Assembling DNA Templates for Studying Optical Phenomena

    NASA Astrophysics Data System (ADS)

    Pilo-Pais, Mauricio

    DNA origami is a novel self-assembly technique that can be used to form various 2D and 3D objects, and to position matter with nanometer accuracy. It has been used to coordinate the placement of nanoscale objects, both organic and inorganic, to make molecular motor and walkers; and to create optically active nanostructures. In this dissertation, DNA origami templates are used to assemble plasmonic structures. Specifically, engineered Surface Enhanced Raman Scattering (SERS) substrates were fabricated. Gold nanoparticles were selectively placed on the corners of rectangular origami and subsequently enlarged via solution-based metal deposition. The resulting assemblies exhibited "hot spots" of enhanced electromagnetic field between the nanoparticles. These hot spots significantly enhanced the Raman signal from Raman molecules covalently attached to the assemblies. Control samples with only one nanoparticle per DNA template, which therefore lacked inter-particle hot spots, did not exhibit strong enhancement. Furthermore, Raman molecules were used to map out the hot spots' distribution, as the molecules are photo-damaged when experiencing a threshold electric field. This method opens up the prospect of using DNA origami to rationally engineer and assemble plasmonic structures for molecular spectroscopy.

  2. Solution-Processed Self-Assembled Nanodielectrics on Template-Stripped Metal Substrates.

    PubMed

    McMorrow, Julian J; Walker, Amanda R; Sangwan, Vinod K; Jariwala, Deep; Hoffman, Emily; Everaerts, Ken; Facchetti, Antonio; Hersam, Mark C; Marks, Tobin J

    2015-12-01

    The coupling of hybrid organic-inorganic gate dielectrics with emergent unconventional semiconductors has yielded transistor devices exhibiting record-setting transport properties. However, extensive electronic transport measurements on these high-capacitance systems are often convoluted with the electronic response of the semiconducting silicon substrate. In this report, we demonstrate the growth of solution-processed zirconia self-assembled nanodielectrics (Zr-SAND) on template-stripped aluminum substrates. The resulting Zr-SAND on Al structures leverage the ultrasmooth (r.m.s. roughness <0.4 nm), chemically uniform nature of template-stripped metal substrates to demonstrate the same exceptional electronic uniformity (capacitance ∼700 nF cm(-2), leakage current <1 μA cm(-2) at -2 MV cm(-1)) and multilayer growth of Zr-SAND on Si, while exhibiting superior temperature and voltage capacitance responses. These results are important to conduct detailed transport measurements in emergent transistor technologies featuring SAND as well as for future applications in integrated circuits or flexible electronics.

  3. Double-level "orthogonal" dynamic combinatorial libraries on transition metal template.

    PubMed

    Goral, V; Nelen, M I; Eliseev, A V; Lehn, J M

    2001-02-13

    Dynamic combinatorial libraries are mixtures of compounds that exist in a dynamic equilibrium and can be driven to compositional self adaptation via selective binding of a specific assembly of certain components to a molecular target. We present here an extension of this initial concept to dynamic libraries that consists of two levels, the first formed by the coordination of terpyridine-based ligands to the transition metal template, and the second, by the imine formation with the aldehyde substituents on the terpyridine moieties. Dialdehyde 7 has been synthesized, converted into a variety of ligands, oxime ethers L(11)-L(33) and acyl hydrazones L(44)-L(77), and subsequently into corresponding cobalt complexes. A typical complex, Co(L(22))(2)(2+) is shown to engage in rapid exchange with a competing ligand L(11) and with another complex, Co(L(22))(2)(2+) in 30% acetonitrile/water at pH 7.0 and 25 degrees C. The exchange in the corresponding Co(III) complexes is shown to be much slower. Imine exchange in the acyl hydrazone complexes (L(44)-L(77)) is strongly controlled by pH and temperature. The two types of exchange, ligand and imine, can thus be used as independent equilibrium processes controlled by different types of external intervention, i.e., via oxidation/reduction of the metal template and/or change in the pH/temperature of the medium. The resulting double-level dynamic libraries are therefore named orthogonal, in similarity with the orthogonal protecting groups in organic synthesis. Sample libraries of this type have been synthesized and showed the complete expected set of components in electrospray ionization MS.

  4. A mixed iron(III)/lithium alkoxide.

    PubMed

    Barley, Helen R L; Kennedy, Alan R; Mulvey, Robert E

    2005-07-01

    The heterometallic alkoxide catena-poly[[tetra-mu2-tert-butoxo-1:2kappa4O:O;1:3kappa4O:O-bis(tetrahydrofuran)-2kappaO,3kappaO-iron(III)dilithium(I)]-mu-bromo], [FeLi2Br(C4H9O)4(C4H8O)2]n, forms a one-dimensional chain through an a-glide. This conformation is achieved through the formation of Fe(III)/O/Li/O rings and Li-Br-Li bridges. PMID:15997061

  5. Water-soluble titanium alkoxide material

    SciTech Connect

    Boyle, Timothy J.

    2010-06-22

    A water soluble, water stable, titanium alkoxide composition represented by the chemical formula (OC.sub.6H.sub.6N).sub.2Ti(OC.sub.6H.sub.2(CH.sub.2N(CH.sub.3).sub.2).sub- .3-2,4,6).sub.2 with a theoretical molecular weight of 792.8 and an elemental composition of 63.6% C, 8.1% H, 14.1% N, 8.1% O and 6.0% Ti.

  6. Bicontinuous ceramics with high surface area from block copolymer templates.

    PubMed

    Hsueh, Han-Yu; Ho, Rong-Ming

    2012-06-01

    Mesoporous polymers with gyroid nanochannels can be fabricated from the self-assembly of degradable block copolymer, polystyrene-b-poly(L-lactide) (PS-PLLA), followed by hydrolysis of PLLA block. Well-defined polymer/ceramic nanohybrid materials with inorganic gyroid nanostructures in a PS matrix can be obtained by using the mesoporous PS as a template for sol-gel reaction. Titanium tetraisopropoxide (TTIP) is used as a precursor to give a model system for the fabrication of metal oxide nanostructures from reactive transition metal alkoxides. By controlling the rates of capillary-driven pore filling and sol-gel reaction, the templated synthesis can be well-developed. Also, by taking advantage of calcination, bicontinuous TiO(2) with controlled crystalline phase (i.e., anatase phase) can be fabricated after removal of the PS template and crystallization of TiO(2) by calcination leading to high photocatalytic efficiency. This new approach provides an easy way to fabricate high-surface-area and high-porosity ceramics with self-supporting structure and controlled crystalline phase for practical applications. As a result, a platform technology to fabricate precisely controlled polymer/ceramic nanohybrids and mesoporous ceramic materials can be established. PMID:22530553

  7. Graphene-Templated Synthesis of Magnetic Metal Organic Framework Nanocomposites for Selective Enrichment of Biomolecules.

    PubMed

    Cheng, Gong; Wang, Zhi-Gang; Denagamage, Sachira; Zheng, Si-Yang

    2016-04-27

    Successful control of homogeneous and complete coating of graphene or graphene-based composites with well-defined metal organic framework (MOF) layers is a great challenge. Herein, novel magnetic graphene MOF composites were constructed via a simple strategy for self-assembly of well-distributed, dense, and highly porous MOFs on both sides of graphene nanosheets. Graphene functionalized with magnetic nanoparticles and carboxylic groups on both sides was explored as the backbone and template to direct the controllable self-assembly of MOFs. The prepared composite materials have a relatively high specific surface area (345.4 m(2) g(-1)), and their average pore size is measured to be 3.2 nm. Their relatively high saturation magnetization (23.8 emu g(-1)) indicates their strong magnetism at room temperature. Moreover, the multifunctional composite was demonstrated to be a highly effective affinity material in selective extraction and separation of low-concentration biomolecules from biological samples, in virtue of the size-selection property of the unique porous structure and the excellent affinity of the composite materials. Besides providing a solution for the construction of well-defined functional graphene-based MOFs, this work could also contribute to selective extraction of biomolecules, in virtue of the universal affinity between immobilized metal ions and biomolecules. PMID:27046460

  8. Scalable salt-templated synthesis of two-dimensional transition metal oxides

    PubMed Central

    Xiao, Xu; Song, Huaibing; Lin, Shizhe; Zhou, Ying; Zhan, Xiaojun; Hu, Zhimi; Zhang, Qi; Sun, Jiyu; Yang, Bo; Li, Tianqi; Jiao, Liying; Zhou, Jun; Tang, Jiang; Gogotsi, Yury

    2016-01-01

    Two-dimensional atomic crystals, such as two-dimensional oxides, have attracted much attention in energy storage because nearly all of the atoms can be exposed to the electrolyte and involved in redox reactions. However, current strategies are largely limited to intrinsically layered compounds. Here we report a general strategy that uses the surfaces of water-soluble salt crystals as growth templates and is applicable to not only layered compounds but also various transition metal oxides, such as hexagonal-MoO3, MoO2, MnO and hexagonal-WO3. The planar growth is hypothesized to occur via a match between the crystal lattices of the salt and the growing oxide. Restacked two-dimensional hexagonal-MoO3 exhibits high pseudocapacitive performances (for example, 300 F cm−3 in an Al2(SO4)3 electrolyte). The synthesis of various two-dimensional transition metal oxides and the demonstration of high capacitance are expected to enable fundamental studies of dimensionality effects on their properties and facilitate their use in energy storage and other applications. PMID:27103200

  9. Scalable salt-templated synthesis of two-dimensional transition metal oxides

    NASA Astrophysics Data System (ADS)

    Xiao, Xu; Song, Huaibing; Lin, Shizhe; Zhou, Ying; Zhan, Xiaojun; Hu, Zhimi; Zhang, Qi; Sun, Jiyu; Yang, Bo; Li, Tianqi; Jiao, Liying; Zhou, Jun; Tang, Jiang; Gogotsi, Yury

    2016-04-01

    Two-dimensional atomic crystals, such as two-dimensional oxides, have attracted much attention in energy storage because nearly all of the atoms can be exposed to the electrolyte and involved in redox reactions. However, current strategies are largely limited to intrinsically layered compounds. Here we report a general strategy that uses the surfaces of water-soluble salt crystals as growth templates and is applicable to not only layered compounds but also various transition metal oxides, such as hexagonal-MoO3, MoO2, MnO and hexagonal-WO3. The planar growth is hypothesized to occur via a match between the crystal lattices of the salt and the growing oxide. Restacked two-dimensional hexagonal-MoO3 exhibits high pseudocapacitive performances (for example, 300 F cm-3 in an Al2(SO4)3 electrolyte). The synthesis of various two-dimensional transition metal oxides and the demonstration of high capacitance are expected to enable fundamental studies of dimensionality effects on their properties and facilitate their use in energy storage and other applications.

  10. The Obtaining of Nano Oxide Systems SiO2-REE with Alkoxide Technology

    NASA Astrophysics Data System (ADS)

    Amelina, Anna; Grinberg, Evgenii

    A lot of oxides systems with REE as dopants are used in catalytic processes in organic synthesis. They are very perspectives as thermostable coating in aerospace technics. These systems are usually based on silicon or aluminium oxides and doped with rare-earth elements. This systems can be produced by different methods. One of the most perspective of them is “sol-gel”-method with silicium, aluminium and rare-earth alkoxides as a precursor of doped silica and alumina, or their derivatives. Thus the obtaining of composite SiO _{2} - REE oxide materials by the hydrolysis doped with rare-earth elements was suggested. Some of alcoholate derivatives such as El(OR)n were used in this processes. The SiO _{2}- REE oxides were precipitated during the sol-gel process, where tetraethoxysilane (TEOS) as used as SiO _{2} sources. Also it is known that alkoxides of alkali metals, including lithium alkoxides, are widely used in industry and synthetic chemistry, as well as a source of lithium in various mixed oxide compositions, such as lithium niobate, lithium tantalate or lithium silicate. Therefore, we attempted to obtain the lithium silicate, which is also doped with rare-earth elements. Lithium silicate was obtained by alkaline hydrolysis of tetraethoxysilane with lithium alkoxide. Lithium alkoxide were synthesized by dissolving at metal in the corresponding alcohol are examined. The dependence of the rate of dissolving of the metal on the method of mixing of the reaction mixture and the degree of metal dispersion was investigated. The mathematical model of the process was composed and also optimization of process was carried out. Some oxide SiO _{2}, Al _{2}O _{3} and rare-earth nanostructured systems were obtained by sol-gel-method. The size of particle was determined by electron and X-ray spectroscopy and was in the range of 5 - 15 nm. Purity of this oxide examples for contaminating of heavy metals consists n.(1E-4...1E-5) wt%. Sols obtained by this method may be used

  11. Controlled fabrication of DNA molecular templates for the deposition and electrical measurement of 1D metal nanowires

    NASA Astrophysics Data System (ADS)

    Barreda, Jorge; Hu, Longqian; Yu, Liuqi; Wang, Zhibin; Xia, Junfei; Guan, Jingjiao; Xiong, Peng; Guan's Group Team; Xiong's Group Team

    Stretched DNA nanowires (NWs) offer a convenient substrate for the fabrication and measurement of 1D metal NWs of width down to nm.So far the fabrication of the DNA templates has replied on somewhat random self-assembly processes. Here we demonstrate a process with high degree of control over the length, spacing, diameter , and orientation of the metal NWs: A one-step dewetting of a DNA solution on a PDMS stamp with an array of micropillars with well-defined pitch yields DNA NWs suspended across the micropillars along a chosen direction. The DNA NWs are then transferred via micro-contact printing onto a Si/SiO2/SiNx substrate with a lithographically fabricated trench defined by an opening in the SiNx layer and undercut in the SiO2 layer. The template with DNA NWs stretched across the trench is placed in a high-vacuum evaporator for metal deposition, resulting in a metal NW of width defined by the diameter of the DNA template (<10 nm) and length determined by the width of the trench. Quasi-four terminal I-V measurements are performed in situ with incremental metal deposition. Concomitant with a transition from strongly nonlinear IV to Ohmic behavior with increasing thickness, the NW resistance is observed to decrease exponentially.

  12. Correlation of photobleaching, oxidation and metal induced fluorescence quenching of DNA-templated silver nanoclusters

    NASA Astrophysics Data System (ADS)

    Morishita, Kiyoshi; Maclean, James L.; Liu, Biwu; Jiang, Hui; Liu, Juewen

    2013-03-01

    Few-atom noble metal nanoclusters have attracted a lot of interest due to their potential applications in biosensor development, imaging and catalysis. DNA-templated silver nanoclusters (AgNCs) are of particular interest as different emission colors can be obtained by changing the DNA sequence. A popular analytical application is fluorescence quenching by Hg2+, where d10-d10 metallophilic interaction has often been proposed for associating Hg2+ with nanoclusters. However, it cannot explain the lack of response to other d10 ions such as Zn2+ and Cd2+. In our effort to elucidate the quenching mechanism, we studied a total of eight AgNCs prepared by different hairpin DNA sequences; they showed different sensitivity to Hg2+, and DNA with a larger cytosine loop size produced more sensitive AgNCs. In all the cases, samples strongly quenched by Hg2+ were also more easily photobleached. Light of shorter wavelengths bleached AgNCs more potently, and photobleached samples can be recovered by NaBH4. Strong fluorescence quenching was also observed with high redox potential metal ions such as Ag+, Au3+, Cu2+ and Hg2+, but not with low redox potential ions. Such metal induced quenching cannot be recovered by NaBH4. Electronic absorption and mass spectrometry studies offered further insights into the oxidation reaction. Our results correlate many important experimental observations and will fuel the further growth of this field.Few-atom noble metal nanoclusters have attracted a lot of interest due to their potential applications in biosensor development, imaging and catalysis. DNA-templated silver nanoclusters (AgNCs) are of particular interest as different emission colors can be obtained by changing the DNA sequence. A popular analytical application is fluorescence quenching by Hg2+, where d10-d10 metallophilic interaction has often been proposed for associating Hg2+ with nanoclusters. However, it cannot explain the lack of response to other d10 ions such as Zn2+ and Cd2+. In

  13. Directing Colloidal Assembly and a Metal-Insulator Transition Using a Quench-Disordered Porous Rod Template

    NASA Astrophysics Data System (ADS)

    Jadrich, Ryan B.; Schweizer, Kenneth S.

    2014-11-01

    Replica and effective-medium theory methods are employed to elucidate how to massively reconfigure a colloidal assembly to achieve globally homogeneous, strongly clustered, and percolated equilibrium states of high electrical conductivity at low physical volume fractions. A key idea is to employ a quench-disordered, large-mesh rigid-rod network as a templating internal field. By exploiting bulk phase separation frustration and the tunable competing processes of colloid adsorption on the low-dimensional network and fluctuation-driven colloid clustering in the pore spaces, two distinct spatial organizations of greatly enhanced particle contacts can be achieved. As a result, a continuous, but very abrupt, transition from an insulating to metallic-like state can be realized via a small change of either the colloid-template or colloid-colloid attraction strength. The approach is generalizable to more complicated template or colloidal architectures.

  14. Preparation of silica stabilized biological templates for the production of metal and layered nanoparticles

    DOEpatents

    Culver, James N; Royston, Elizabeth; Brown, Adam; Harris, Michael

    2013-02-26

    The present invention relates to a system and method providing for increased silica growth on a bio-template, wherein the bio-template is pretreated with aniline to produce a uniform silica attractive surface and yielding a significant silica layers of at least 10 nm, and more preferably at least 20 nm in thickness, thereby providing for a high degree of stability to the bio-template.

  15. Metal-organic framework nanocrystals as sacrificial templates for hollow and exceptionally porous titania and composite materials.

    PubMed

    Yang, Hui; Kruger, Paul E; Telfer, Shane G

    2015-10-01

    We report a strategy that employs metal-organic framework (MOF) crystals in two roles for the fabrication of hollow nanomaterials. In the first role the MOF crystals provide a template on which a shell of material can be deposited. Etching of the MOF produces a hollow structure with a predetermined size and morphology. In combination with this strategy, the MOF crystals, including guest molecules in their pores, can provide the components of a secondary material that is deposited inside the initially formed shell. We used this approach to develop a straightforward and reproducible method for constructing well-defined, nonspherical hollow and exceptionally porous titania and titania-based composite nanomaterials. Uniform hollow nanostructures of amorphous titania, which assume the cubic or polyhedral shape of the original template, are delivered using nano- and microsized ZIF-8 and ZIF-67 crystal templates. These materials exhibit outstanding textural properties including hierarchical pore structures and BET surface areas of up to 800 m(2)/g. As a proof of principle, we further demonstrate that metal nanoparticles such as Pt nanoparticles, can be encapsulated into the TiO2 shell during the digestion process and used for subsequent heterogeneous catalysis. In addition, we show that the core components of the ZIF nanocrystals, along with their adsorbed guests, can be used as precursors for the formation of secondary materials, following their thermal decomposition, to produce hollow and porous metal sulfide/titania or metal oxide/titania composite nanostructures.

  16. Self-assembled bifunctional surface mimics an enzymatic and templating protein for the synthesis of a metal oxide semiconductor

    PubMed Central

    Kisailus, David; Truong, Quyen; Amemiya, Yosuke; Weaver, James C.; Morse, Daniel E.

    2006-01-01

    The recent discovery and characterization of silicatein, a mineral-synthesizing enzyme that assembles to form the filamentous organic core of the glassy skeletal elements (spicules) of a marine sponge, has led to the development of new low-temperature synthetic routes to metastable semiconducting metal oxides. These protein filaments were shown in vitro to catalyze the hydrolysis and structurally direct the polycondensation of metal oxides at neutral pH and low temperature. Based on the confirmation of the catalytic mechanism and the essential participation of specific serine and histidine residues (presenting a nucleophilic hydroxyl and a nucleophilicity-enhancing hydrogen-bonding imidazole nitrogen) in silicatein’s catalytic active site, we therefore sought to develop a synthetic mimic that provides both catalysis and the surface determinants necessary to template and structurally direct heterogeneous nucleation through condensation. Using lithographically patterned poly(dimethylsiloxane) stamps, bifunctional self-assembled monolayer surfaces containing the essential catalytic and templating elements were fabricated by using alkane thiols microcontact-printed on gold substrates. The interface between chemically distinct self-assembled monolayer domains provided the necessary juxtaposition of nucleophilic (hydroxyl) and hydrogen-bonding (imidazole) agents to catalyze the hydrolysis of a gallium oxide precursor and template the condensed product to form gallium oxohydroxide (GaOOH) and the defect spinel, gamma-gallium oxide (γ-Ga2O3). Using this approach, the production of patterned substrates for catalytic synthesis and templating of semiconductors for device applications can be envisioned. PMID:16585518

  17. (110) Orientation growth of magnetic metal nanowires with face-centered cubic structure using template synthesis technique

    SciTech Connect

    Wang Xuewei; Yuan Zhihao; Li Jushan

    2011-06-15

    A template-assisted assembly technique has been used to synthesize magnetic metal nanowire arrays. Fe, Co, Ni nanowires are fabricated using direct-current electrodeposition in the pores of anodic alumina membranes. The morphology and the crystal structure of the samples are characterized by field-emission scanning electron microscopy, transmission electron microscopy, and X-ray diffractometer. The results indicate that Fe, Co, and Ni nanowires all have face-centered cubic (FCC) structure and a preferred orientation along the [110] direction. The ability to prepare well-defined orientation growth of magnetic metal nanowires with FCC structure opens up new opportunities for both fundamental studies and nanodevice applications. - Research Highlights: {yields} Fe, Co, and Ni nanowires are fabricated in the AAM templates by electrodeposition. {yields} Well-defined orientation growth of the nanowires with FCC structure were investigated. {yields} The electrodeposition parameters affect the crystal structure and growth orientation.

  18. Hotspot-engineered quasi-3D metallic network for surface-enhanced Raman scattering based on colloid monolayer templating

    NASA Astrophysics Data System (ADS)

    Du, Wei; Liu, Long; Gu, Ping; Hu, Jingguo; Zhan, Peng; Liu, Fanxin; Wang, Zhenlin

    2016-09-01

    A hotspot-engineered quasi-3D metallic network with controllable nanogaps is purposed as a high-quality surface-enhanced Raman scattering (SERS) substrate, which is prepared by a combination of non-close-packed colloid monolayer templating and metal physical deposition. The significant SERS effect arises from a strongly enhanced local electric field originating from the ultra-small-gaps between neighboring metal-caps and tiny interstices and between the metal-caps and the metal-bumps on the base, which is recognized by the numerical simulation. A remarkable average SERS enhancement factor of up to 1.5 × 108 and a SERS intensity relative standard deviation (RSD) of 10.5% are achieved by optimizing the nanogap size to sub-10 nm scale, leading to an excellent capability for Raman detection, which is represented by the clearly identified SERS signal of the Rhodamine 6G solution with a fairly low concentration of 1 nM.

  19. An in situ self-assembly template strategy for the preparation of hierarchical-pore metal-organic frameworks

    PubMed Central

    Huang, Hongliang; Li, Jian-Rong; Wang, Keke; Han, Tongtong; Tong, Minman; Li, Liangsha; Xie, Yabo; Yang, Qingyuan; Liu, Dahuan; Zhong, Chongli

    2015-01-01

    Metal-organic frameworks (MOFs) have recently emerged as a new type of nanoporous materials with tailorable structures and functions. Usually, MOFs have uniform pores smaller than 2 nm in size, limiting their practical applications in some cases. Although a few approaches have been adopted to prepare MOFs with larger pores, it is still challenging to synthesize hierarchical-pore MOFs (H-MOFs) with high structural controllability and good stability. Here we demonstrate a facile and versatile method, an in situ self-assembly template strategy for fabricating stable H-MOFs, in which multi-scale soluble and/or acid-sensitive metal-organic assembly (MOA) fragments form during the reactions between metal ions and organic ligands (to construct MOFs), and act as removable dynamic chemical templates. This general strategy was successfully used to prepare various H-MOFs that show rich porous properties and potential applications, such as in large molecule adsorption. Notably, the mesopore sizes of the H-MOFs can be tuned by varying the amount of templates. PMID:26548441

  20. A new route toward ultrasensitive, flexible chemical sensors: metal nanotubes by wet-chemical synthesis along sacrificial nanowire templates.

    PubMed

    Lim, Mi Ae; Kim, Dong Hwan; Park, Chong-Ook; Lee, Young Wook; Han, Sang Woo; Li, Zhiyong; Williams, R Stan; Park, Inkyu

    2012-01-24

    We developed a novel low-temperature, wet-chemical process for the facile synthesis of metal nanotube arrays through the reduction of metal precursors along sacrificial metal oxide nanowire templates and demonstrated its applications to the ultrasensitive, low-power, mechanically robust, and flexible chemical sensors. The in situ dissolution of ZnO nanowire templates, which were hydrothermally grown on electrode surfaces, during the reaction allows the direct formation of tubular Pd nanostructures on the sensor devices without the need of complex processes for device integration or template removal. Moreover, this simple synthesis was carried out at low-temperature with mild chemical conditions; therefore we could make Pd nanotube devices not only on silicon substrates but also on flexible polymer substrates. The H(2) sensing of such Pd nanotube devices was investigated under various mechanical loading and showed excellent reliability and robustness. The sensitivity of our devices was found to be at least 2 orders of magnitude higher than literature values for H(2) sensors, which can be attributed to the high surface area and the well-formed interconnect of Pd tubular nanostructures in our devices.

  1. Soft-Templating Synthesis and Properties of Mesoporous Alumina-Titania

    SciTech Connect

    Morris, Stacy M; Horton, Jr, Joe A; Jaroniec, Mietek

    2010-01-01

    Mesoporous alumina-titania materials, having various molar compositions of aluminum and titanium, were synthesized via cooperative self-assembly of the corresponding metal alkoxides and Pluronic P123 triblock copolymer (soft template) in ethanolic solution under acidic conditions. The resulting mixed metal oxides possess ordered mesopores at low to equal molar compositions of titanium in relation to aluminum (up to 50%) and worm-like mesostructures at higher molar compositions of titanium (50-75%). In addition, these mesoporous oxides exhibit high BET surface areas (up to 438 m2/g), large pore widths (from 7.37 to 18.55 nm) and pore volumes (from 0.16 to 0.64 cm3/g), narrow pore size distributions, crystalline pore walls and high thermal stability.

  2. Synthesis of metal nanowires using nanocracks and DNA-templates and their characterization

    NASA Astrophysics Data System (ADS)

    Mani, Sathyanarayanan

    A major challenge in the field of nanotechnology is the synthesis and testing of nanostructures, such as nanowires, in a cost effective manner. Currently, there are two general approaches for fabricating nanowires, namely top-down and bottom-up. While the top-down approach that uses nano-lithography is controlled but expensive, the bottom-up approach that uses self-assembly is inexpensive but uncontrolled. This research, describes the mechanism behind an innovative and inexpensive method that combines both the top-down and bottom-up approaches to produce metal nanowires. The method uses cracks in PECVD silicon dioxide thin films on silicon substrate as molds to produce electroless deposited nickel nanowires. The cracks are initiated from voids formed due to nonconformal deposition of oxide on RIE etched trenches in silicon substrate. A model was developed to characterize void formation and the stress response of these oxide films during a thermal ramp, and identify the operating conditions such as film deposit thickness, trench dimensions and annealing temperature for controlled crack pattern formation. The nickel nanowires (50-250 nm wide) are polycrystalline with grain size ranging between 10 to 50 nm. Electrical characterization revealed that the resistivity of these wires decreased 10 times on sintering. However, this resistivity was still twice that of their bulk counterpart. This higher resistivity can be explained by the enhanced scattering of conductive electrons by grain boundaries and phosphorous impurities. An alternate nanowire fabrication technique that simplifies their testing by enabling their direct integration with MEMS test-beds has also been presented. In this approach, commercially available lambda DNA's (16.1 microns long and 2 nm wide) are used as templates to form nanowires of various metals through sputter deposition or evaporation. The test-bed is compatible with commercially available TEM stages for conducting in situ nanostructural

  3. Template-induced diverse metal-organic materials as catalysts for the tandem acylation-Nazarov cyclization.

    PubMed

    Huang, Chao; Ding, Ran; Song, Chuanjun; Lu, Jingjing; Liu, Lu; Han, Xiao; Wu, Jie; Hou, Hongwei; Fan, Yaoting

    2014-12-01

    In our continuing quest to develop a metal-organic framework (MOF)-catalyzed tandem pyrrole acylation-Nazarov cyclization reaction with α,β-unsaturated carboxylic acids for the synthesis of cyclopentenone[b]pyrroles, which are key intermediates in the synthesis of natural product (±)-roseophilin, a series of template-induced Zn-based (1-3) metal-organic frameworks (MOFs) have been solvothermally synthesized and characterized. Structural conversions from non-porous MOF 1 to porous MOF 2, and back to non-porous MOF 3 arising from the different concentrations of template guest have been observed. The anion-π interactions between the template guests and ligands could affect the configuration of ligands and further tailor the frameworks of 1-3. Futhermore, MOFs 1-3 have shown to be effective heterogeneous catalysts for the tandem acylation-Nazarov cyclization reaction. In particular, the unique structural features of 2, including accessible catalytic sites and suitable channel size and shape, endow 2 with all of the desired features for the MOF-catalyzed tandem acylation-Nazarov cyclization reaction, including heterogeneous catalyst, high catalytic activity, robustness, and excellent selectivity. A plausible mechanism for the catalytic reaction has been proposed and the structure-reactivity relationship has been further clarified. Making use of 2 as a heterogeneous catalyst for the reaction could greatly increase the yield of total synthesis of (±)-roseophilin. PMID:25303356

  4. Micelle-Template Synthesis of Nitrogen-Doped Mesoporous Graphene as an Efficient Metal-Free Electrocatalyst for Hydrogen Production

    PubMed Central

    Huang, Xiaodan; Zhao, Yufei; Ao, Zhimin; Wang, Guoxiu

    2014-01-01

    Synthesis of mesoporous graphene materials by soft-template methods remains a great challenge, owing to the poor self-assembly capability of precursors and the severe agglomeration of graphene nanosheets. Herein, a micelle-template strategy to prepare porous graphene materials with controllable mesopores, high specific surface areas and large pore volumes is reported. By fine-tuning the synthesis parameters, the pore sizes of mesoporous graphene can be rationally controlled. Nitrogen heteroatom doping is found to remarkably render electrocatalytic properties towards hydrogen evolution reactions as a highly efficient metal-free catalyst. The synthesis strategy and the demonstration of highly efficient catalytic effect provide benchmarks for preparing well-defined mesoporous graphene materials for energy production applications. PMID:25523276

  5. Crackle template based metallic mesh with highly homogeneous light transmission for high-performance transparent EMI shielding

    NASA Astrophysics Data System (ADS)

    Han, Yu; Lin, Jie; Liu, Yuxuan; Fu, Hao; Ma, Yuan; Jin, Peng; Tan, Jiubin

    2016-05-01

    Our daily electromagnetic environment is becoming increasingly complex with the rapid development of consumer electronics and wireless communication technologies, which in turn necessitates the development of electromagnetic interference (EMI) shielding, especially for transparent components. We engineered a transparent EMI shielding film with crack-template based metallic mesh (CT-MM) that shows highly homogeneous light transmission and strong microwave shielding efficacy. The CT-MM film is fabricated using a cost-effective lift-off method based on a crackle template. It achieves a shielding effectiveness of ~26 dB, optical transmittance of ~91% and negligible impact on optical imaging performance. Moreover, high–quality CT-MM film is demonstrated on a large–calibre spherical surface. These excellent properties of CT-MM film, together with its advantages of facile large-area fabrication and scalability in processing on multi-shaped substrates, make CT-MM a powerful technology for transparent EMI shielding in practical applications.

  6. Poly(cyclohexylethylene)-block-poly(ethylene oxide) block polymers for metal oxide templating

    SciTech Connect

    Schulze, Morgan W.; Sinturel, Christophe

    2015-09-01

    A series of poly(cyclohexylethylene)-block-poly(ethylene oxide) (CEO) diblock copolymers were synthesized through tandem anionic polymerizations and heterogeneous catalytic hydrogenation. Solvent-annealed CEO diblock films were used to template dense arrays of inorganic oxide nanodots via simple spin coating of an inorganic precursor solution atop the ordered film. The substantial chemical dissimilarity of the two blocks enables (i) selective inclusion of the inorganic precursor within the PEO domain and (ii) the formation of exceptionally small feature sizes due to a relatively large interaction parameter estimated from mean-field analysis of the order–disorder transition temperatures of compositionally symmetric samples. UV/ozone treatment following incorporation produces an ordered arrangement of oxide nanodots and simultaneously removes the block polymer template. However, we report the smallest particles (6 ± 1 nm) templated from a selective precursor insertion method to date using a block polymer scaffold.

  7. A meta-analysis of the mechanical properties of ice-templated ceramics and metals

    NASA Astrophysics Data System (ADS)

    Deville, Sylvain; Meille, Sylvain; Seuba, Jordi

    2015-08-01

    Ice templating, also known as freeze casting, is a popular shaping route for macroporous materials. Over the past 15 years, it has been widely applied to various classes of materials, and in particular ceramics. Many formulation and process parameters, often interdependent, affect the outcome. It is thus difficult to understand the various relationships between these parameters from isolated studies where only a few of these parameters have been investigated. We report here the results of a meta analysis of the structural and mechanical properties of ice templated materials from an exhaustive collection of records. We use these results to identify which parameters are the most critical to control the structure and properties, and to derive guidelines for optimizing the mechanical response of ice templated materials. We hope these results will be a helpful guide to anyone interested in such materials.

  8. Poly(cyclohexylethylene)-block-poly(ethylene oxide) block polymers for metal oxide templating

    DOE PAGES

    Schulze, Morgan W.; Sinturel, Christophe; Hillmyer, Marc A.

    2015-09-01

    A series of poly(cyclohexylethylene)-block-poly(ethylene oxide) (CEO) diblock copolymers were synthesized through tandem anionic polymerizations and heterogeneous catalytic hydrogenation. Solvent-annealed CEO diblock films were used to template dense arrays of inorganic oxide nanodots via simple spin coating of an inorganic precursor solution atop the ordered film. The substantial chemical dissimilarity of the two blocks enables (i) selective inclusion of the inorganic precursor within the PEO domain and (ii) the formation of exceptionally small feature sizes due to a relatively large interaction parameter estimated from mean-field analysis of the order–disorder transition temperatures of compositionally symmetric samples. UV/ozone treatment following incorporation produces anmore » ordered arrangement of oxide nanodots and simultaneously removes the block polymer template. However, we report the smallest particles (6 ± 1 nm) templated from a selective precursor insertion method to date using a block polymer scaffold.« less

  9. DEXTROSE-TEMPLATED MICROWAVE-ASSISTED COMBUSTION SYNTHESIS OF SPONGY METAL OXIDES

    EPA Science Inventory

    Microwave-assisted combustion synthesis of porous nanocrystalline titania and carbon coated titania is reported using dextrose as template and the product was compared with the one obtained using conventional heating furnace. Out of three compositions viz., 1:1, 1:3, and 1:5 (met...

  10. Influence of lead(II) lone pairs on the serpentine structures for heterometallic alkoxides

    SciTech Connect

    Teff, D.J.; Huffman, J.C.; Caulton, K.G.

    1995-05-10

    Heterometallic alkoxides, M{sub a}M{sub b}{prime}(OR){sub m}, most often adopts closed polyhedral structures, in part to give suitably high coordination numbers to all metals. In general, the ratio m/(a + b) is typically low (because one or more of M and M{prime} are low valent) so that {mu}{sub 2}- and {mu}{sub 3}-OR functionalities are required, and a closed polyhedron best accommodates such demands. Thus the metals of KZr{sub 2}(O{sup i}Pr){sub 9}{sup 2} and [BaZr{sub 2}(O{sup i}Pr){sub 10}]{sub 2}{sup 3} form triangles, those of K{sub 2}Zr{sub 2}(O{sup t}Bu){sub 10}{sup 4} form a diamond, and those of K{sub 4}Zr{sub 2}O(O{sup i}Pr){sub 10}{sup 2} form an octahedron. The authors report here the very different outcome of combining Zr(IV) with the soft divalent metal Pb(II). These results demonstrate that rational synthetic control of two different stoichiometries can be effected in heterometallic alkoxide chemistry.

  11. General Self-Template Synthesis of Transition-Metal Oxide and Chalcogenide Mesoporous Nanotubes with Enhanced Electrochemical Performances.

    PubMed

    Wang, Huan; Zhuo, Sifei; Liang, Yu; Han, Xiling; Zhang, Bin

    2016-07-25

    The development of a general strategy for synthesizing hierarchical porous transition-metal oxide and chalcogenide mesoporous nanotubes, is still highly challenging. Herein we present a facile self-template strategy to synthesize Co3 O4 mesoporous nanotubes with outstanding performances in both the electrocatalytic oxygen-evolution reaction (OER) and Li-ion battery via the thermal-oxidation-induced transformation of cheap and easily-prepared Co-Asp(cobalt-aspartic acid) nanowires. The initially formed thin layers on the precursor surfaces, oxygen-induced outward diffusion of interior precursors, the gas release of organic oxidation, and subsequent Kirkendall effect are important for the appearance of the mesoporous nanotubes. This self-template strategy of low-cost precursors is found to be a versatile method to prepare other functional mesoporous nanotubes of transition-metal oxides and chalcogenides, such as NiO, NiCo2 O4 , Mn5 O8 , CoS2 and CoSe2 . PMID:27239778

  12. Oxidation effect on templating of metal oxide nanoparticles within block copolymers

    SciTech Connect

    Akcora, Pinar; Briber, Robert M.; Kofinas, Peter

    2009-06-30

    Amphiphilic norbornene-b-(norbornene dicarboxylic acid) diblock copolymers with different block ratios were prepared as templates for the incorporation of iron ions using an ion exchange protocol. The disordered arrangement of iron oxide particles within these copolymers was attributed to the oxidation of the iron ions and the strong interactions between iron oxide nanoparticles, particularly at high iron ion concentrations, which was found to affect the self-assembly of the block copolymer morphologies.

  13. Synthesis and characterisation of new titanium amino-alkoxides: precursors for the formation of TiO2 materials.

    PubMed

    Hollingsworth, Nathan; Kanna, Miki; Kociok-Köhn, Gabriele; Molloy, Kieran C; Wongnawa, Sumpun

    2008-02-01

    Reaction of the amino-alkoxides HOCH(CH(2)NMe(2))(2) (Hbdmap) and HOC(CH(2)NMe(2))(3) (Htdmap) with [Ti(OR)(4)] yields a series of heteroleptic titanium alkoxides [Ti(OR)(4-n)(L)(n)] (L = bdmap, tdmap). Substitution of the monodentate alkoxide with the chelating alkoxides becomes progressively more difficult, with homogeneous products being obtained only for n = 1, 2. The structure of [Ti(OEt)(3)(bdmap)](2), a mu-OEt bridged dimer, has been determined. Hydrolysis of [Ti(OR)(2)(L)(2)], by adventitious moisture affords the dimeric oxo-alkoxides [Ti(O)(L)(2)](2), both of which have been characterised crystallographically. These two compounds have also been prepared by reaction of [Ti(NMe(2))(2)(L)(2)] with the hydrated metal salts [Zn(acac)(2).2H(2)O] and [Zn(OAc)(2).2H(2)O] using the intrinsic water molecules in these salts to react with the labile amido groups, though the former also produces Me(Me(2)N)C=C(H)C(O)Me from reaction of liberated HNMe(2) with the coordinated acac ligand, while the latter also affords the ligand exchange product [Zn(OAc)(bdmap)]. In neither case does the free dimethylamino group of [Ti(O)(L)(2)](2) coordinate a second metal. The dimeric structure of [Zn(OAc)(bdmap)](2) has been established, and the structure of the tetrameric oxo-alkoxide [Ti(O)(OPr(i))(OCH(2)CH(2)NMe(2))](4) is reported for comparison with others in this study. [Ti(OEt)(3)(bdmap)](2) has been used as a precursor in AACVD (Aerosol-Assisted Chemical Vapour Deposition) to generate amorphous TiO(2) films on glass at 440 degrees C, and TiO(2)@C nanoparticles of approximate diameter 350 nm with a carbon coating of width ca. 75 nm on heating in a sealed container at 700 degrees C. PMID:18217119

  14. Crackle template based metallic mesh with highly homogeneous light transmission for high-performance transparent EMI shielding

    PubMed Central

    Han, Yu; Lin, Jie; Liu, Yuxuan; Fu, Hao; Ma, Yuan; Jin, Peng; Tan, Jiubin

    2016-01-01

    Our daily electromagnetic environment is becoming increasingly complex with the rapid development of consumer electronics and wireless communication technologies, which in turn necessitates the development of electromagnetic interference (EMI) shielding, especially for transparent components. We engineered a transparent EMI shielding film with crack-template based metallic mesh (CT-MM) that shows highly homogeneous light transmission and strong microwave shielding efficacy. The CT-MM film is fabricated using a cost-effective lift-off method based on a crackle template. It achieves a shielding effectiveness of ~26 dB, optical transmittance of ~91% and negligible impact on optical imaging performance. Moreover, high–quality CT-MM film is demonstrated on a large–calibre spherical surface. These excellent properties of CT-MM film, together with its advantages of facile large-area fabrication and scalability in processing on multi-shaped substrates, make CT-MM a powerful technology for transparent EMI shielding in practical applications. PMID:27151578

  15. Template-directed covalent conjugation of DNA to native antibodies, transferrin and other metal-binding proteins

    NASA Astrophysics Data System (ADS)

    Rosen, Christian B.; Kodal, Anne L. B.; Nielsen, Jesper S.; Schaffert, David H.; Scavenius, Carsten; Okholm, Anders H.; Voigt, Niels V.; Enghild, Jan J.; Kjems, Jørgen; Tørring, Thomas; Gothelf, Kurt V.

    2014-09-01

    DNA-protein conjugates are important in bioanalytical chemistry, molecular diagnostics and bionanotechnology, as the DNA provides a unique handle to identify, functionalize or otherwise manipulate proteins. To maintain protein activity, conjugation of a single DNA handle to a specific location on the protein is often needed. However, preparing such high-quality site-specific conjugates often requires genetically engineered proteins, which is a laborious and technically challenging approach. Here we demonstrate a simpler method to create site-selective DNA-protein conjugates. Using a guiding DNA strand modified with a metal-binding functionality, we directed a second DNA strand to the vicinity of a metal-binding site of His6-tagged or wild-type metal-binding proteins, such as serotransferrin, where it subsequently reacted with lysine residues at that site. This method, DNA-templated protein conjugation, facilitates the production of site-selective protein conjugates, and also conjugation to IgG1 antibodies via a histidine cluster in the constant domain.

  16. Surprisingly facile CO2 insertion into cobalt alkoxide bonds: A theoretical investigation

    PubMed Central

    Offermans, Willem K; Bizzarri, Claudia; Leitner, Walter

    2015-01-01

    Summary Exploiting carbon dioxide as co-monomer with epoxides in the production of polycarbonates is economically highly attractive. More effective catalysts for this reaction are intensively being sought. To promote better understanding of the catalytic pathways, this study uses density functional theory calculations to elucidate the reaction step of CO2 insertion into cobalt(III)–alkoxide bonds, which is also the central step of metal catalysed carboxylation reactions. It was found that CO2 insertion into the cobalt(III)–alkoxide bond of [(2-hydroxyethoxy)CoIII(salen)(L)] complexes (salen = N,N”-bis(salicyliden-1,6-diaminophenyl)) is exothermic, whereby the exothermicity depends on the trans-ligand L. The more electron-donating this ligand is, the more exothermic the insertion step is. Interestingly, we found that the activation barrier decreases with increasing exothermicity of the CO2 insertion. Hereby, a linear Brønsted–Evans–Polanyi relationship was found between the activation energy and the reaction energy. PMID:26425188

  17. Explosives: Metal-Organic Framework Templated Synthesis of Copper Azide as the Primary Explosive with Low Electrostatic Sensitivity and Excellent Initiation Ability (Adv. Mater. 28/2016).

    PubMed

    Wang, Qianyou; Feng, Xiao; Wang, Shan; Song, Naimeng; Chen, Yifa; Tong, Wenchao; Han, Yuzhen; Yang, Li; Wang, Bo

    2016-07-01

    On page 5837, L. Yang, B. Wang, and co-workers describe a metal-organic framework (MOF) templating method to synthesize copper azide uniformly anchored in a 3D interconnected carbon matrix and evenly spaced by the electron-conductive joints. This strategy sheds light on the preparation of powerful yet safe primary explosives and fulfills the need for controllable explosive systems.

  18. Regio- and enantiospecific rhodium-catalyzed allylic etherification reactions using copper(I) alkoxides: influence of the copper halide salt on selectivity.

    PubMed

    Evans, P Andrew; Leahy, David K

    2002-07-10

    The transition metal-catalyzed allylic etherification represents a fundamentally important cross-coupling reaction for the construction of allylic ethers. We have developed a new regio- and enantiospecific rhodium-catalyzed allylic etherification of acyclic unsymmetrical allylic alcohol derivatives using copper(I) alkoxides derived from primary, secondary and tertiary alcohols. This study demonstrates that the choice of copper(I) halide salt is crucial for obtaining excellent regio- and enantiospecificity, providing another example of the effect of halide ions in asymmetric transition metal-catalyzed reactions. Finally, the ability to alter the reactivity of the alkali metal alkoxides in this manner may provide a useful method for related metal-catalyzed cross-coupling reactions involving heteroatoms.

  19. Fast and reversible insertion of carbon dioxide into zirconocene-alkoxide bonds. A mechanistic study.

    PubMed

    Brink, Alice; Truedsson, Ida; Fleckhaus, André; Johnson, Magnus T; Norrby, Per Ola; Roodt, Andreas; Wendt, Ola F

    2014-06-21

    In two consecutive equilibria the compound (Cp*)2Zr(OMe)2 undergoes insertion of CO2 to form the mono- and bis-hemicarbonates. Both equilibria are exothermic but entropically disfavoured. Magnetisation transfer experiments gave kinetic data for the first equilibrium showing that the rate of insertion is overall second order with a rate constant of 3.20 ± 0.12 M(-1) s(-1), which is substantially higher than those reported for other early transition metal alkoxides, which are currently the best homogeneous catalysts for dimethyl carbonate formation from methanol and CO2. Activation parameters for the insertion reaction point to a highly ordered transition state and we interpret that as there being a substantial interaction between the CO2 and the metal during the C-O bond formation. This is supported by DFT calculations showing the lateral attack by CO2 to have the lowest energy transition state. PMID:24796283

  20. Synthesis and characterization of cerium and yttrium alkoxide complexes supported by ferrocene-based chelating ligands.

    PubMed

    Broderick, Erin M; Thuy-Boun, Peter S; Guo, Neng; Vogel, Carola S; Sutter, Jörg; Miller, Jeffrey T; Meyer, Karsten; Diaconescu, Paula L

    2011-04-01

    Two series of Schiff base metal complexes were investigated, where each series was supported by an ancillary ligand incorporating a ferrocene backbone and different N=X functionalities. One ligand is based on an imine, while the other is based on an iminophosphorane group. Cerium(IV), cerium(III), and yttrium(III) alkoxide complexes supported by the two ligands were synthesized. All metal complexes were characterized by cyclic voltammetry. Additionally, NMR, Mössbauer, X-ray absorption near-edge structure (XANES), and absorption spectroscopies were used. The experimental data indicate that iron remains in the +2 oxidation state and that cerium(IV) does not engage in a redox behavior with the ancillary ligand.

  1. Ammonium-crown ether supramolecular cation-templated assembly of an unprecedented heterobicluster-metal coordination polymer with enhanced NLO properties.

    PubMed

    Zhang, Jinfang; Jia, Ding; Humphrey, Mark G; Meng, Suci; Zaworotko, Michael J; Cifuentes, Marie P; Zhang, Chi

    2016-03-01

    An ammonium-crown ether host-guest supramolecular cation-templated synthetic methodology has been developed to construct a structurally unprecedented heterobicluster-metal coordination polymer (HCM-CP 1) based on tetranuclear clusters [WS4Cu3](+) with different connection environments, pentanuclear clusters [WS4Cu4](2+), and Cu(+) building metal ions. HCM-CP 1 exhibits enhanced NLO properties, which may be ascribed to the incorporation of diverse building cluster components.

  2. Ammonium-crown ether supramolecular cation-templated assembly of an unprecedented heterobicluster-metal coordination polymer with enhanced NLO properties.

    PubMed

    Zhang, Jinfang; Jia, Ding; Humphrey, Mark G; Meng, Suci; Zaworotko, Michael J; Cifuentes, Marie P; Zhang, Chi

    2016-03-01

    An ammonium-crown ether host-guest supramolecular cation-templated synthetic methodology has been developed to construct a structurally unprecedented heterobicluster-metal coordination polymer (HCM-CP 1) based on tetranuclear clusters [WS4Cu3](+) with different connection environments, pentanuclear clusters [WS4Cu4](2+), and Cu(+) building metal ions. HCM-CP 1 exhibits enhanced NLO properties, which may be ascribed to the incorporation of diverse building cluster components. PMID:26864604

  3. Polymer grafting surface as templates for the site-selective metallization

    NASA Astrophysics Data System (ADS)

    Yang, Fang; Li, Peiyuan; Li, Xiangcheng; Huo, Lini; Chen, Jinhao; Chen, Rui; Na, Wei; Tang, Wanning; Liang, Lifang; Su, Wei

    2013-06-01

    We report a simple, low-cost and universal method for the fabrication of copper circuit patterns on a wide range of flexible polymeric substrates. This method relies on procedures to modify the polymeric substrates with grafted polymer template to form surface-bound N-containing groups, which can bind palladium catalysts that subsequently initiate the site-selective deposition of copper granular layer patterns. The fabrications of patterned copper films were demonstrated on three kinds of flexible polymeric films including poly(imide) (PI), poly(ethylene naphthalate) (PEN) and poly(ethylene terephthalate) (PET) with minimum feature sizes of 200 μm. The films were characterized by ATR FT-IR, contact angle, XPS, XRD, TEM, SEM. Furthermore, the copper layered structure shows good adhesion with polymeric film. This method, which provides a promising strategy for the fabrication of copper circuit patterns on flexible polymeric substrates, has the potential in manufacturing conductive features adopted in various fields including modern electronics, opto-electronics and photovoltaic applications.

  4. Metal-organic gel templated synthesis of magnetic porous carbon for highly efficient removal of organic dyes.

    PubMed

    Wang, Luhuan; Ke, Fei; Zhu, Junfa

    2016-03-21

    Magnetic porous carbon composites are promising materials in various applications, such as adsorbents, supercapacitors and catalyst supports, due to their high surface area, thermal and chemical stability, and easy separation. However, despite the increasing number of reports of magnetic porous carbon composites, the preparation of these materials with environmentally friendly procedures still remains a great challenge. Herein, we report a facile method to prepare a magnetic porous carbon composite with high surface area from a Fe-based metal-organic gel (MOG) template, an extended structure of a metal-organic framework (MOF). The obtained magnetic porous carbon composite was applied to remove organic dyes from an aqueous solution by selecting methyl orange (MO) as a model molecule. It exhibits excellent adsorption capacity (182.82 mg g(-1)), fast adsorption kinetics (8.13 × 10(-3) g mg(-1) min(-1)), and a perfect magnetic separation performance for the MO removal. This study demonstrates a new way to achieve clean synthesis of magnetic porous carbon materials, and opens a new door for the application of MOGs in organic dye removal.

  5. Metallotropic liquid crystals formed by surfactant templating of molten metal halides.

    PubMed

    Martin, James D; Keary, Cristin L; Thornton, Todd A; Novotnak, Mark P; Knutson, Jeremey W; Folmer, Jacob C W

    2006-04-01

    Liquid crystals consist of anisotropic molecular units, and most are organic molecules. Materials incorporating metals into anisotropic molecules, described as metallomesogens, have been prepared. Anisotropic structures such as one-dimensional chains and two-dimensional layers are frequently observed in solid-state inorganic materials, however, little is understood about structural organization in melts of such materials. Achieving liquid-crystalline behaviour in inorganic fluids should be possible if the anisotropic structure can be retained or designed into the molten phase. We demonstrated the ability to engineer zeolite-type structures into metal halide glasses and liquids. In this work we have engineered lamellar, cubic and hexagonal liquid-crystalline structure in metal-halide melts by controlling the volume fraction and nature of the inorganic block (up to 80 mol%) with respect to alkylammonium surfactants. The high metal content of these liquid-crystalline systems significantly advances the field of metallomesogens, which seeks to combine magnetic, electronic, optical, redox and catalytic properties common to inorganic materials with the fluid properties of liquid crystals. PMID:16547520

  6. Mixed protein-templated luminescent metal clusters (Au and Pt) for H2O2 sensing

    PubMed Central

    2013-01-01

    A simple and cost-effective method to synthesize the luminescent noble metal clusters (Au and Pt) in chicken egg white aqueous solution at room temperature is reported. The red-emitting Au cluster is used as fluorescent probe for sensitive detection of H2O2. PMID:23601828

  7. General one-pot template-free hydrothermal method to metal oxide hollow spheres and their photocatalytic activities and lithium storage properties.

    PubMed

    Li, Di; Qin, Qing; Duan, Xiaochuan; Yang, Jiaqin; Guo, Wei; Zheng, Wenjun

    2013-09-25

    A general and facile one-pot template-free hydrothermal strategy has been developed to synthesize various metal oxide (TiO2, SnO2 and α-Fe2O3) hollow spheres with unified morphologies. The formation of hollow structure involves a trifluoroacetic acid (TFA)-assisted Ostwald ripening process. Photocatalytic activities of the as-prepared TiO2 product are evaluated by the photodegradation of Rhodamine B (RhB), which the TiO2 hollow spheres obtained from 450 °C thermal treatment exhibit higher photocatalytic activity than Degussa P25. In addition, electrochemical measurements demonstrate that all of the as-prepared metal oxides hollow spheres have the potential applications in lithium-ion battery. We have a great expectation that this synthesis strategy can afford a new universal route for functional metal oxide hollow materials preparation without using template.

  8. Heterolysis of Dihydrogen by Silver Alkoxides and Fluorides.

    PubMed

    Tate, Brandon K; Nguyen, Jenna T; Bacsa, John; Sadighi, Joseph P

    2015-07-01

    Alkoxide-bridged disilver cations react with dihydrogen to form hydride-bridged cations, releasing free alcohol. Hydrogenolysis of neutral silver fluorides affords hydride-bridged disilver cations as their bifluoride salts. These reactions proceed most efficiently when the supporting ligands are expanded N-heterocyclic carbenes (NHCs) derived from 6- and 7-membered cyclic amidinium salts. Kinetics studies show that silver fluoride hydrogenolysis is first-order in both silver and dihydrogen.

  9. Highly Soluble Alkoxide Magnesium Salts for Rechargeable Magnesium Batteries

    SciTech Connect

    Liao, Chen; Guo, Bingkun; Jiang, Deen; Custelcean, Radu; Mahurin, Shannon Mark; Sun, Xiao-Guang; Dai, Sheng

    2014-01-01

    A unique class of air-stable and non-pyrophoric magnesium electrolytes has been developed based on alkoxide magnesium compounds. The crystals obtained from this class of electrolytes exhibit a unique structure of tri-magnesium cluster, [Mg3Cl3(OR)2(THF)6]+ [(THF)MgCl3] . High reversible capacities and good rate capabilities were obtained in Mg-Mo6S8 batteries using these new electrolytes at both 20 and 50 oC.

  10. Photochemical Fabrication of Transition Metal Nanoparticles Using CdS Template and Their Co-Catalysis Effects for TiO2 Photocatalysis

    NASA Astrophysics Data System (ADS)

    Badhwar, Nidhi; Gupta, Nidhi; Pal, Bonamali

    2013-06-01

    Transition metal nanoparticles were prepared by chemical dissolution of CdS template from metal photodeposited CdS nanorod (length = 70-85 nm and width = 5-6 nm) heterocomposites. Size (9-10 nm) of metal nanoparticles obtained after CdS removal was larger than the size (4-6 nm) of metal nanodeposits over CdS template. The obtained Au nanoparticles displayed a broad red shifted absorption band at 660 nm, whereas Pt, Pd and Rh nanoparticles exhibit featureless absorption spectra. Elemental analysis confirms the complete removal of CdS template from Au-CdS (Au — 2.65 at.%) and Ag-CdS (Ag — 2.06 at.%) composites showing no Cd peak. These metal nanoparticles imparted dissimilar co-catalytic activity of TiO2 for photocatalytic degradation of salicylic acid in the order Au > Pt > Pd > Ag > Rh as a function of their nature, electronegativity, redox potential and work function.

  11. Site-selective metallization of polymeric substrates by the hyperbranched polymer templates

    NASA Astrophysics Data System (ADS)

    Li, Peiyuan; Yang, Fang; Li, Xiangcheng; He, Chunling; Su, Wei; Chen, Jinhao; Huo, Lini; Chen, Rui; Lu, Chensheng; Liang, Lifang

    2013-09-01

    We demonstrate a simple, cost-effective and universal technique for the fabrication of copper circuit pattern on flexible polymeric substrate. This method relies on a ternary polyethylenimine-poly(acrylic acid)-substrate film incorporating palladium catalysts, which are used as adhesive interlayers for the copper metallization of flexible polymeric substrates. We demonstrated the fabrication of patterned copper films on a variety of flexible polymers with minimum feature sizes of 200 μm. And the resulting copper circuit showed strong adhesion with underlying flexible polymeric substrates. The films were characterized by ATR FT-IR, contact angle, XPS, XRD, TEM and SEM. The direct patterning of metallic circuit on flexible polymeric substrate indicates great potential for the use in electronics industry.

  12. OPAA template-directed synthesis and optical properties of metal nanocrystals

    PubMed Central

    2013-01-01

    Ag and Cu nanocrystals (NCs) were assembled into ordered porous anodic alumina (OPAA) by a single-potential-step chronoamperometry technique. The composition, morphology, microstructure, and optical property were analyzed by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, and optical absorption spectroscopy. The results indicate that metallic NCs/OPAA composite possesses a significant surface plasmon resonance absorption. For continuous electrodeposition, metallic nanowires are smooth and uniform with face-centered cubic (fcc) single-crystalline structure; however, for interval electrodeposition, the nanowires are bamboo-like or pearl-chain-like with fcc polycrystalline structure. The length of the nanoparticle nanowires or the single-crystalline nanowires can be controlled well by adjusting the experimental cycle times or the continuous depositing time. The transverse dipole resonance of metallic NCs enhances and displays a blue shift with increasing electrodeposition time or experimental cycle times, which is consistent with Zong's results but contradictory to Duan's results. The formation mechanisms of the nanoparticle nanowires and the single-crystalline nanowires were discussed in detail. PMID:23866967

  13. Fabrication and characterization of poly(methyl methacrylate) microchannels by in situ polymerization with a novel metal template.

    PubMed

    Chen, Zhifeng; Gao, Yunhua; Su, Rongguo; Li, Chengwu; Lin, Jinming

    2003-09-01

    A stainless steel template for the fabrication of plastic microfluidic devices has been developed by photolithography and chemical etching technique. The preparation process of the template is simple, rapid, and low-cost. The cross sectional profiles of raised microchannels on the template are trapezoidal. The surface roughness of the templates was controlled down to 190 nm. The template can be used repeatedly to generate devices reproducibly. The microfluidic devices of poly(methyl methacrylate) (PMMA) were fabricated by in situ polymerization using the templates. The reproducibility of the fabricated microchannel is high and the relative standard deviation is 0.7% by the in situ polymerization approach. Some physical properties of the polymerized microchannels were characterized including the transparency, the thermal deformation temperature, and the dimensional information. Current monitoring was used to evaluate the electroosmotic flow within the microchannels under the electric field strength of 300 V/cm. PMID:14518052

  14. Nanoparticle-based immunosensor with apoferritin templated metallic phosphate label for quantification of phosphorylated acetylcholinesterase

    SciTech Connect

    Du, Dan; Chen, Aiqiong; Xie, Yunying; Zhang, Aidong; Lin, Yuehe

    2011-05-15

    A new sandwich-like electrochemical immunosensor has been developed for quantification of organophosphorylated acetylcholinesterase (OP-AChE), an exposure biomarker of organophosphate pesticides and nerve agents. Zirconia nanoparticles (ZrO2 NPs) were anchored on a screen printed electrode (SPE) to preferably capture OP-AChE adducts by metal chelation with phospho-moieties, which was selectively recognized by lead phosphate-apoferritin labeled anti-AChE antibody (LPA-anti-AChE). The sandwich-like immunoreactions were performed among ZrO2 NPs, OP-AChE and LPA-anti-AChE to form ZrO2/OP-AChE/LPA-anti-AChE complex and the released lead ions were detected on a disposable SPE. The binding affinity was investigated by both square wave voltammetry (SWV) and quartz crystal microbalance (QCM) measurements. The proposed immunosensor yielded a linear response current over a broad OP-AChE concentrations range from 0.05 nM to 10 nM, with detection limit of 0.02 nM, which has enough sensitivity for monitoring of low-dose exposure to OPs. This method avoids the drawback of unavailability of commercial OP-specific antibody as well as amplifies detection signal by using apoferritin encoded metallic phosphate nanoparticle tags. This nanoparticle-based immunosensor offers a new method for rapid, sensitive, selective and inexpensive quantification of phosphorylated adducts for monitoring of OP pesticides and nerve agents exposures.

  15. Efficient removal of heavy metal ions with biopolymer template synthesized mesoporous titania beads of hundreds of micrometers size.

    PubMed

    Wu, Na; Wei, Huanhuan; Zhang, Lizhi

    2012-01-01

    We demonstrated that mesoporous titania beads of uniform size (about 450 μm) and high surface area could be synthesized via an alginate biopolymer template method. These mesoporous titania beads could efficiently remove Cr(VI), Cd(II), Cr(III), Cu(II), and Co(II) ions from simulated wastewater with a facile subsequent solid-liquid separation because of their large sizes. We chose Cr(VI) removal as the case study and found that each gram of these titania beads could remove 6.7 mg of Cr(VI) from simulated wastewater containing 8.0 mg·L(-1) of Cr(VI) at pH = 2.0. The Cr(VI) removal process was found to obey the Langmuir adsorption model and its kinetics followed pseudo-second-order rate equation. The Cr(VI) removal mechanism of titania beads might be attributed to the electrostatic adsorption of Cr(VI) ions in the form of negatively charged HCrO(4)(-) by positively charged TiO(2) beads, accompanying partial reduction of Cr(VI) to Cr(III) by the reductive surface hydroxyl groups on the titania beads. The used titania beads could be recovered with 0.1 mol·L(-1) of NaOH solution. This study provides a promising micro/nanostructured adsorbent with easy solid-liquid separation property for heavy metal ions removal. PMID:22129207

  16. Efficient removal of heavy metal ions with biopolymer template synthesized mesoporous titania beads of hundreds of micrometers size.

    PubMed

    Wu, Na; Wei, Huanhuan; Zhang, Lizhi

    2012-01-01

    We demonstrated that mesoporous titania beads of uniform size (about 450 μm) and high surface area could be synthesized via an alginate biopolymer template method. These mesoporous titania beads could efficiently remove Cr(VI), Cd(II), Cr(III), Cu(II), and Co(II) ions from simulated wastewater with a facile subsequent solid-liquid separation because of their large sizes. We chose Cr(VI) removal as the case study and found that each gram of these titania beads could remove 6.7 mg of Cr(VI) from simulated wastewater containing 8.0 mg·L(-1) of Cr(VI) at pH = 2.0. The Cr(VI) removal process was found to obey the Langmuir adsorption model and its kinetics followed pseudo-second-order rate equation. The Cr(VI) removal mechanism of titania beads might be attributed to the electrostatic adsorption of Cr(VI) ions in the form of negatively charged HCrO(4)(-) by positively charged TiO(2) beads, accompanying partial reduction of Cr(VI) to Cr(III) by the reductive surface hydroxyl groups on the titania beads. The used titania beads could be recovered with 0.1 mol·L(-1) of NaOH solution. This study provides a promising micro/nanostructured adsorbent with easy solid-liquid separation property for heavy metal ions removal.

  17. Explosives: Metal-Organic Framework Templated Synthesis of Copper Azide as the Primary Explosive with Low Electrostatic Sensitivity and Excellent Initiation Ability (Adv. Mater. 28/2016).

    PubMed

    Wang, Qianyou; Feng, Xiao; Wang, Shan; Song, Naimeng; Chen, Yifa; Tong, Wenchao; Han, Yuzhen; Yang, Li; Wang, Bo

    2016-07-01

    On page 5837, L. Yang, B. Wang, and co-workers describe a metal-organic framework (MOF) templating method to synthesize copper azide uniformly anchored in a 3D interconnected carbon matrix and evenly spaced by the electron-conductive joints. This strategy sheds light on the preparation of powerful yet safe primary explosives and fulfills the need for controllable explosive systems. PMID:27442967

  18. Cadmium amido alkoxide and alkoxide precursors for the synthesis of nanocrystalline CdE (E=S,Se, Te).

    SciTech Connect

    Boyle, Timothy J.; Avilucea, Gabriel; Bunge, Scott D.; Alam, Todd Michael; Headley, Thomas Jeffrey; Holland, Gregory P.

    2004-12-01

    The synthesis and characterization of a family of alternative precursors for the production of CdE nanoparticles (E = S, Se, and Te) is reported. The reaction of Cd(NR{sub 2}){sub 2} where NR{sub 2} = N(SiMe{sub 3}){sub 2} with n HOR led to the isolation of the following: n = 1 [Cd({mu}-OCH{sub 2}CMe{sub 3})(NR{sub 2})(py)]{sub 2} (1, py = pyridine), Cd[({mu}-OC{sub 6}H{sub 3}(Me){sub 2}-2,6){sub 2}Cd(NR{sub 2})(py)]{sub 2} (2), [Cd({mu}-OC{sub 6}H{sub 3}(CHMe{sub 2}){sub 2}-2,6)(NR{sub 2})(py)]{sub 2} (3), [Cd({mu}-OC{sub 6}H{sub 3}(CMe{sub 3}){sub 2}-2,6)(NR{sub 2})(py)]{sub 2} (4), [Cd({mu}-OC{sub 6}H{sub 2}(NH{sub 2}){sub 3}-2,4,6)(NR{sub 2})(py)]{sub 2} (5), and n = 2 [Cd({mu}-OC{sub 6}H{sub 3}(Me){sub 2}-2,6)(OC{sub 6}H{sub 3}(Me){sub 2}-2,6)(py){sub 2}]{sub 2} (6), and [Cd({mu}-OC{sub 6}H{sub 3}(CMe{sub 3}){sub 2}-2,6)(OC{sub 6}H{sub 3}(CMe{sub 3}){sub 2}-2,6)(THF)]{sub 2} (7). For all but 2, the X-ray crystal structures were solved as discrete dinuclear units bridged by alkoxide ligands and either terminal -NR{sub 2} or -OR ligands depending on the stoichiometry of the initial reaction. For 2, a trinuclear species was isolated using four {mu}-OR and two terminal -NR{sub 2} ligands. The coordination of the Cd metal center varied from 3 to 5 where the higher coordination numbers were achieved by binding Lewis basic solvents for the less sterically demanding ligands. These complexes were further characterized in solution by {sup 1}H, {sup 13}C, and {sup 113}Cd NMR along with solid-state {sup 113}Cd NMR spectroscopy. The utility of these complexes as 'alternative precursors' for the controlled preparation of nanocrystalline CdS, CdSe, and CdTe was explored. To synthesize CdE nanocrystals, select species from this family of compounds were individually heated in a coordinating solvent (trioctylphosphine oxide) and then injected with the appropriate chalcogenide stock solution. Transmission electron spectroscopy and UV-vis spectroscopy were used to characterize

  19. Synthesis, structural characterization, IR- and Raman spectroscopy, magnetic properties of new organically templated metal sulfates with 4-aminopyridinium

    NASA Astrophysics Data System (ADS)

    Bednarchuk, Tamara J.; Kinzhybalo, Vasyl; Bednarchuk, Oleksandr; Pietraszko, Adam

    2016-09-01

    Crystal structures of the series of twelve 4-aminopyridinium templated metal sulfates: (C5H7N2)2[MeII(H2O)6](SO4)2 (MeII = Cu (1), Co (2), Mg (3), Zn (4), Fe (5), Mn (6a)), (C5H7N2)2[MeII(H2O)4(SO4)2]·4H2O (MeII = Mn (6b), Cd (7a)), (C5H7N2)2[MnII(H2O)4(SO4)2] (6c), (C5H7N2)2[Cd(H2O)4(SO4)2] (7b), (C5H7N2)[Al(H2O)6](SO4)2·4H2O (low (8lt) and room temperature (8rt) phases) and (C5H7N2)[FeIII(H2O)4(SO4)2] (9) were determined by single-crystal X-ray diffraction. Compounds 1-6a are isostructural, crystal structure consists of [Me(H2O)6]2+ octahedra, 4-aminopyridinium cations (4ap) and sulfate anions. Crystal packing in 1-6a series is characterized by alternating 4ap and inorganic layers. In the structure of 1 Cu2+ coordination environment is axially deformed due to Jahn-Teller effect to tetragonal bipyramidal. Compounds 6 (a, b) and 7a at ambient conditions dehydrate to produce isostructural complexes 6c and 7b, respectively. In structures of 6c, 7b and 9 sulfate anions are involved in slightly distorted octahedral metal coordination composed of six O atoms from four water molecules and two sulfate anions. Room temperature phase of 8 is characterized by disorder of 4ap around center of inversion. Continuous phase transition at ≈185 K leads to the cell doubling and ordering of 4ap. All of the structures are governed by an extensive three-dimensional hydrogen bond networks, as well as π-π interactions visualized by Hirshfeld surface analysis. Moreover, selected compounds were characterized by the IR and Raman spectroscopy and magnetic measurement studies.

  20. Accelerated subcritical drying of large alkoxide silica gels

    NASA Astrophysics Data System (ADS)

    Wang, Shiho; Kirkbir, Fikret; Chaudhuri, S. R.; Sarkar, Arnab

    1992-12-01

    Fracture during drying has been the key hurdle in fabrication of large monolithic silica glass from alkoxide gels. Although existing literature suggests pore enlargement, aging, chemical additives, supercritical drying and freeze drying as helpful in avoiding fracture during drying, successful accelerated sub-critical drying of large silica monoliths from alkoxide gels has not yet been reported. In the present approach, acid catalyzed sols of TEOS, ethanol and water (pH equals 2) were cast as cylindrical rods in plastic molds of 8.0 and 10.0 cm diameter with volumes of 2000 cc and 3000 cc respectively. The resultant gels were aged for about 7 days and dried in a specially designed chamber under sub-critical conditions of the pore field. We have obtained monolithic dry gels in drying times of 3 - 7 days for sizes of 2000 - 3000 cc. The dry gels have narrow unimodal pore size distributions, with average pore radius of about 20 angstroms as measured by BET. Although capillary stress during drying increases with reduction of pore size, it was found that in this approach it is easier to dry gels of smaller pore size.

  1. Reactivity of divalent germanium alkoxide complexes is in sharp contrast to the heavier tin and lead analogues.

    PubMed

    Ferro, Lorenzo; Hitchcock, Peter B; Coles, Martyn P; Fulton, J Robin

    2012-02-01

    The chemistry of β-diketiminate germanium alkoxide complexes has been examined and shown to be in sharp contrast to its heavier congeners. For instance, (BDI)GeOR (BDI = [{N(2,6-(i)Pr(2)C(6)H(3))C(Me)}(2)CH], R = (i)Pr, (s)Bu, (t)Bu) does not react with carbon dioxide to form a metal carbonate complex. Addition of aliphatic electrophiles, such as methyl iodide or methyl triflate, results in the net oxidative addition to the germanium, giving cationic tetravalent germanium complexes, [(BDI)Ge(Me)OR][X] (X = I, OTf). An examination of the contrasting reactivities of the alkoxide ligand and the germanium loan pair with Lewis acids yielded the unusual germanium(II)-copper(I) adduct, {μ(2)-Cu(2)I(2)}[(BDI)GeO(t)Bu](2). This complex not only displays a rare example of a divalent Ge-Cu bond, but is the first example in which a planar Cu(2)I(2) diamond core possesses a three-coordinate copper bound to another metal center. PMID:22242862

  2. Nanowire-directed templating synthesis of metal-organic framework nanofibers and their derived porous doped carbon nanofibers for enhanced electrocatalysis.

    PubMed

    Zhang, Wang; Wu, Zhen-Yu; Jiang, Hai-Long; Yu, Shu-Hong

    2014-10-15

    A nanowire-directed templating synthesis of metal-organic framework (MOF) nanofibers has been demonstrated, where ultrathin tellurium nanowires (TeNWs) with excellent dispersivity can act as templates for directed growth and assembly of ZIF-8 nanocrystals (one typical MOF), resulting in the formation of uniform ZIF-8 nanofibers. The as-obtained ZIF-8 nanofibers can be conveniently converted into highly porous doped carbon nanofibers by calcination. Compared with bulk porous carbon by direct carbonization of MOF crystals, these doped carbon nanofibers exhibit complex network structure, hierarchical pores, and high surface area. Further doped by phosphorus species, the co-doped carbon nanofibers exhibit excellent electrocatalytic performance for oxygen reduction reaction, even better than the benchmark Pt/C catalyst.

  3. Amine-templated one-dimensional metal sulfates including a mixed-valent Fe compound with a half-kagome structure.

    PubMed

    Behera, J N; Rao, C N R

    2006-11-20

    Organically templated metal sulfates are relatively new. Six amine-templated transition-metal sulfates with different types of chain structures, including a novel iron sulfate with a chain structure corresponding to one half of the kagome structure, were synthesized by hydro/solvothermal methods. Amongst the one-dimensional metal sulfates, [C10N2H10][Zn(SO4)Cl2] (1) is the simplest, being formed by corner-linked ZnO2Cl2 and SO4 tetrahedra. [C6N2H18][Mn(SO4)2(H2O)2] (2) and [C2N2H10][Ni(SO4)2(H2O)2] (3) have ladder structures comprising four-membered rings formed by SO4 tetrahedra and metal-oxygen octahedra, just as in the mineral kröhnkite. [C4N2H12][V(III)(OH)(SO4)2]H2O (4) and [C4N2H12][VF3(SO4)] (5) exhibit chain topologies of the minerals tancoite and butlerite, respectively. The structure of [C4N2H12][H3O][Fe(III)Fe(II) F6(SO4)] (6) is noteworthy in that it corresponds to half of the hexagonal kagome structure. It exhibits ferrimagnetic properties at low temperatures and the absence of frustration, unlike the mixed-valent iron sulfate with the full kagome structure.

  4. A Qualitative Analysis of a "Bora-Brook Rearrangement": The Ambident Reactivity of Boryl-Substituted Alkoxide Including the Carbon-to-Oxygen Migration of a Boryl Group.

    PubMed

    Kisu, Haruki; Sakaino, Hirotoshi; Ito, Fumihiro; Yamashita, Makoto; Nozaki, Kyoko

    2016-03-16

    A bora-Brook rearrangement, i.e., the migration of boryl group from a carbon to an oxygen atom in an isolated α-boryl-substituted alkoxide, was examined, and decisive factors for the acceleration of this reaction are disclosed. In this rearrangement, the boryl-substituted alkoxide exhibited ambiphilic reactivity toward electrophiles to afford two types of products, which are electrophiles bound either at the oxygen or at the carbon atom. Using polar solvents, a saturated backbone of the boron-containing heterocycle, or larger alkali metal cations resulted in a significantly increased reaction rate of base-catalyzed isomerization of α-borylbenzyl alcohol including the bora-Brook rearrangement. PMID:26907676

  5. Covalent heterogenization of discrete bis(8-quinolinolato)dioxomolybdenum(VI) and dioxotungsten(VI) complexes by a metal-template/metal-exchange method: Cyclooctene epoxidation catalysts with enhanced performances

    SciTech Connect

    Yang, Ying; Chattopadhyay, Soma; Shibata, Tomohiro; Ren, Yang; Lee, Sungsik; Kan, Qiubin

    2014-10-01

    A metal-template/metal-exchange method was used to imprint covalently attached bis(8- quinolinolato)dioxomolybdenum(VI) and dioxotungsten(VI) complexes onto large surface-area, mesoporous SBA-15 silica to obtain discrete MoO2 VIT and WO2 VIT catalysts bearing different metal loadings, respectively. Homogeneous counterparts, MoO2 VIN and WO2 VIN, as well as randomly ligandgrafted heterogeneous analogues, MoO2 VIG and WO2 VIG, were also prepared for comparison. X-ray absorption fine structure (XAFS), pair distribution function (PDF) and UV–vis data demonstrate that MoO2 VIT and WO2 VIT adopt a more solution-like bis(8-quinolinol) coordination environment than MoO2 VIG and WO2 VIG, respectively. Correspondingly, the templated MoVI and WVI catalysts show superior performances to their randomly grafted counterparts and neat analogues in the epoxidation of cyclooctene. It is found that the representative MoO2 VIT-10% catalyst can be recycled up to five times without significant loss of reactivity, and heterogeneity test confirms the high stability of MoO2 VIT-10% catalyst against leaching of active species into solution. The homogeneity of the discrete bis(8-quinolinol) metal spheres templated on SBA-15 should be responsible for the superior performances.

  6. Structural and optical characterization of metal tungstates (MWO4; M=Ni, Ba, Bi) synthesized by a sucrose-templated method

    PubMed Central

    2013-01-01

    Background Metal tungstates have attracted much attention due to their interesting structural and photoluminescence properties. Depending on the size of the bivalent cation present, the metal tungstates will adopt structures with different phases. In this work, three different phases of metal tungstates MWO4 (M= Ba, Ni and Bi) were synthesized via the sucrose templated method. Results The powders of BaWO4 (tetragonal), NiWO4 (monoclinic) and Bi2WO6 (orthorhombic) formed after calcination temperatures of 750, 650 and 600°C for 4 h respectively are found to be crystalline and exist in their pure phase. Based on Scherrer estimation, their crystallite size are of nanosized. BET results showed NiWO4 has the highest surface area. BaWO4 exhibited less Raman vibrations than the NiWO4 because of the increased lattice symmetry but Bi2WO6 showed almost the same Raman vibrations as BaWO4. From the UV-vis spectra, the band gap transition of the metal tungstates are of the order of BaWO4 > Bi2WO6 > NiWO4. Broad blue-green emission peaks were detected in photoluminescence spectra and the results showed the great dependence on morphology, crystallinity and size of the metal tungstates. Conclusion Three different phases of metal tungstates of BaWO4 (scheelite), NiWO4 (wolframite) and Bi2WO6 (perovskite layer) in their pure phase were successfully prepared by the simple and economical sucrose-templated method. The highest surface area is exhibited by NiWO4 while largest band gap is shown by BaWO4. These materials showed promising optical properties. PMID:23634962

  7. Cubic nitride templates

    DOEpatents

    Burrell, Anthony K; McCleskey, Thomas Mark; Jia, Quanxi; Mueller, Alexander H; Luo, Hongmei

    2013-04-30

    A polymer-assisted deposition process for deposition of epitaxial cubic metal nitride films and the like is presented. The process includes solutions of one or more metal precursor and soluble polymers having binding properties for the one or more metal precursor. After a coating operation, the resultant coating is heated at high temperatures under a suitable atmosphere to yield metal nitride films and the like. Such films can be used as templates for the development of high quality cubic GaN based electronic devices.

  8. Electron Microscopy of Modified Aluminum Alkoxide Microstructures on Freeze-Drying

    PubMed

    Srivastava; Menon; Bellare

    1997-07-15

    Direct imaging of microstructures in chelated aluminum alkoxide systems subjected to freeze-drying and freeze-thaw-drying is reported using cryo-scanning electron microscopy (SEM) and SEM techniques. Aluminum sec-butoxide was chelated with a beta-diketoester in different molar ratios. This system was gelled by hydrolysis under intense sonication. The sonogels formed were subjected to cryo-SEM. Samples for cryo-SEM were made by freezing the chelated alkoxide samples in liquid nitrogen and freeze-fracturing them inside the cryo-SEM and monitoring the apparent morphological changes on exposure to the cryo-SEM environment including intentional sample heating. Microstructures of unchelated, 1:1 chelated and 1:2 chelated (alkoxide:chelate) sonogels after freezing, thawing, and drying were also imaged by SEM techniques. Heterogeneity introduced by chelation of alkoxide is proposed as the cause for the formation of flakes in freeze-thaw-dried chelated alkoxide gels. Microstructures of 1:1 chelated freeze dried alkoxide were compared with the freeze-thaw-dried gels. The absence of flakes in the chelated samples when subjected to in situ freeze-drying indicated reversible nature of the gels. PMID:9268538

  9. The first organically templated open-framework metal-sulfites with layered and three-dimensional diamondoid structures.

    PubMed

    Tiwari, Ranjay K; Kumar, Jitendra; Behera, J N

    2016-01-21

    The crystallographic signatures and characterization data of two novel organically templated open-framework zinc-sulfites (NH3CH2CH2NH3)[Zn3(SO3)4], 1, and (CN3H6)2[Zn(SO3)2], 2, are reported for the first time, synthesized under hydrothermal conditions using different amines, namely, ethylenediamine and guanidine, to generate 2D (for 1) and 3D (for 2) assemblies with 4-, 6-, 8- and 12-membered rings.

  10. Reactivity of boranes with a titanium(IV) amine tris(phenolate) alkoxide complex; formation of a Ti(IV) tetrahydroborate complex, a Ti(III) dimer and a Ti(IV) hydroxide Lewis acid adduct.

    PubMed

    Johnson, Andrew L; Davidson, Matthew G; Mahon, Mary F

    2007-12-14

    Treatment of the titanium(IV) alkoxide complex [Ti(Oi Pr)(OC6Me2H(2)CH2)3N] (2) with BH3.THF, as part of a study into the utility and reactivity of (2) in the metal mediated borane reduction of acetophenone, results in alkoxide-hydride exchange and formation of the structurally characterised titanium(iv) tetrahydroborate complex [Ti{BH4}(OC6Me2H2CH2)3N] (3). Complex (3) readily undergoes reduction to form the isolable titanium(III) species [Ti(OC6Me2H2CH2)3N]2 (4). Reaction of (2) with B(C6F5)3 results in formation of the Lewis acid adduct [Ti(OC6Me2H2CH2)3N][HO.B(C6F5)3] (5). In comparison, treatment of the less sterically encumbered alkoxide Ti(Oi Pr)4 with B(C6F5)3 results in alkoxide-aryl exchange and formation of the organometallic titanium complex [Ti(Oi Pr)3(C6F5)]2 (6). The molecular structures of 3, 4, 5 and 6 have been determined by X-ray diffraction.

  11. Synthesis and thermolytic behavior of mixed-valence homo- and heterometallic group 14 alkoxides

    SciTech Connect

    Teff, D.J.; Minear, C.D.; Baxter, D.V.; Caulton, K.G.

    1998-05-18

    The mixed-valence molecule Sn{sup II}Sn{sup IV} (OPr){sub 6} is conveniently synthesized and is shown to exchange bridging and terminal alkoxides in solution in its Sn({micro}-OPr){sub 3}Sn(OPr){sub 3} structure. Pb{sub 3}SnO(POr){sub 8} is synthesized and shown to undergo an intramolecular fluxional process in solution. Both molecules are sufficiently volatile for CVD study, and comparison of CVD behaviors of these and of M(OPr){sub 2} (M = Sn, Pb), Sn(POr){sub 4}, SnZr(OPr){sub 6}, and Pb{sub 3}-ZrO(OPr){sub 8} shows the reducing capacity of the isopropoxide moiety dominates the thermolytic behavior of all these species, giving metallic Sn or Pb in all cases. Only Zr, when it is present, forms ZrO{sub 2}. The oxide in Pb{sub 3}SnO(POr){sub 8}yields PbO (and 2 Pb{sup 0} and 1 Sn{sup 0}), in contrast to the relative electropositivity of Sn and Pb, a fact attributed to kinetic control of CVD behavior.

  12. Study of bismuth alkoxides as possible precursors for ALD.

    PubMed

    Hatanpää, Timo; Vehkamäki, Marko; Ritala, Mikko; Leskelä, Markku

    2010-04-01

    While searching for bismuth precursors for thin film preparation by atomic layer deposition (ALD) three bismuth alkoxides Bi(O(t)Bu)(3) (1), Bi(OCMe(2)(i)Pr)(3) (2), Bi(OC(i)Pr(3))(3) (3), bismuth beta-diketonate, Bi(thd)(3) (4), and bismuth carboxylate, Bi(O(2)C(t)Bu)(3) (5), were synthesized and evaluated. The compounds were characterized by CHN, NMR, MS, and TGA/SDTA. Earlier unknown crystal structures of compounds 1 and 3 were solved. Compound 1 forms dimeric and loose polymeric structures in the solid state while 3 is strictly monomeric. For compound 2 crystals suitable for complete structure solution could not be grown. Crystallization trials of 2 from hexane and toluene resulted in oxygen bridged tetramer [Bi(2)O(OCMe(2)(i)Pr)(4)](2) (6). Compound 4 has dimeric structure and compound 5 forms loose tetramers as reported earlier. The structure of toluene solvated crystal [Bi(O(2)C(t)Bu)(3)](4).2MeC(6)H(5) (7) was solved. All compounds studied showed relatively good volatility and thermal stability. They were all tested in ALD deposition experiments, in which compound 2 was found to be the most suitable for ALD growth of Bi(2)O(3). It exhibited a clear improvement over Bi precursors studied earlier.

  13. Small angle x-ray scattering: Instrument development and studies of protein aggregation, cellulose hydrolysis, and the production of nanoporous metals using surfactact templates

    NASA Astrophysics Data System (ADS)

    Banuelos, Jose Leobardo

    explored using surfactant-templated metal systems. In this, as with many materials for possible energy storage applications, chemically stable systems with good mechanical strength, high temperature resistance, and high surface areas are desirable. Time- dependent SAXS measurements were used to study the templating of Pt and Pd metals onto a surfactant structure. The reduction of these metals was carried out using two methods, reduction with ascorbate and using hydrogen-nitrogen gas mixtures.

  14. Syntheses of rare-earth metal oxide nanotubes by the sol-gel method assisted with porous anodic aluminum oxide templates

    SciTech Connect

    Kuang Qin; Lin Zhiwei; Lian Wei; Jiang Zhiyuan; Xie Zhaoxiong Huang Rongbin; Zheng Lansun

    2007-04-15

    In this paper, we report a versatile synthetic method of ordered rare-earth metal (RE) oxide nanotubes. RE (RE=Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) oxide nanotubes were successfully prepared from corresponding RE nitrate solution via the sol-gel method assisted with porous anodic aluminum oxide (AAO) templates. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM, and X-ray diffraction (XRD) have been employed to characterize the morphology and composition of the as-prepared nanotubes. It is found that as-prepared RE oxides evolve into bamboo-like nanotubes and entirely hollow nanotubes. A new possible formation mechanism of RE oxide nanotubes in the AAO channels is proposed. These high-quantity RE oxide nanotubes are expected to have promising applications in many areas such as luminescent materials, catalysts, magnets, etc. - Graphical abstract: A versatile synthetic method for the preparation of ordered rare-earth (RE) oxide nanotubes is reported, by which RE (RE=Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) oxide nanotubes were successfully prepared from corresponding RE nitrate solution via the sol-gel method assisted with porous anodic aluminum oxide (AAO) templates.

  15. Template-Free 3D Microprinting of Metals Using a Force-Controlled Nanopipette for Layer-by-Layer Electrodeposition.

    PubMed

    Hirt, Luca; Ihle, Stephan; Pan, Zhijian; Dorwling-Carter, Livie; Reiser, Alain; Wheeler, Jeffrey M; Spolenak, Ralph; Vörös, János; Zambelli, Tomaso

    2016-03-23

    A novel 3D printing method for voxel-by-voxel metal printing is presented. Hollow atomic force microscopy (AFM) cantilevers are used to locally supply metal ions in an electrochemical cell, enabling a localized electroplating reaction. By exploiting the deflection feedback of these probes, electrochemical 3D metal printing is, for the first time, demonstrated in a layer-by-layer fashion, enabling the fabrication of arbitrary-shaped geometries.

  16. Template-Free 3D Microprinting of Metals Using a Force-Controlled Nanopipette for Layer-by-Layer Electrodeposition.

    PubMed

    Hirt, Luca; Ihle, Stephan; Pan, Zhijian; Dorwling-Carter, Livie; Reiser, Alain; Wheeler, Jeffrey M; Spolenak, Ralph; Vörös, János; Zambelli, Tomaso

    2016-03-23

    A novel 3D printing method for voxel-by-voxel metal printing is presented. Hollow atomic force microscopy (AFM) cantilevers are used to locally supply metal ions in an electrochemical cell, enabling a localized electroplating reaction. By exploiting the deflection feedback of these probes, electrochemical 3D metal printing is, for the first time, demonstrated in a layer-by-layer fashion, enabling the fabrication of arbitrary-shaped geometries. PMID:26783090

  17. Self-formation of highly aligned metallic, semiconducting and single chiral single-walled carbon nanotubes assemblies via a crystal template method

    SciTech Connect

    Kawai, Hideki; Hasegawa, Kai; Yanagi, Kazuhiro; Oyane, Ayako; Naitoh, Yasuhisa

    2014-09-01

    The fabrication of an aligned array of single-walled carbon nanotubes (SWCNTs) with a single chiral state has been a significant challenge for SWCNT applications as well as for basic science research. Here, we developed a simple, unique technique to produce assemblies in which metallic, semiconducting, and single chiral state SWCNTs were densely and highly aligned. We utilized a crystal of surfactant as a template on which mono-dispersed SWCNTs in solution self-assembled. Micro-Raman measurements and scanning electron microscopy measurements clearly showed that the SWCNTs were highly and densely aligned parallel to the crystal axis, indicating that approximately 70% of the SWCNTs were within 7° of being parallel. Moreover, the assemblies exhibited good field effect transistor characteristics with an on/off ratio of 1.3 × 10{sup 5}.

  18. Carbonaceous spheres—an unusual template for solid metal oxide mesoscale spheres: Application to ZnO spheres

    SciTech Connect

    Patrinoiu, Greta; Calderón-Moreno, Jose Maria; Culita, Daniela C.; Birjega, Ruxandra; Ene, Ramona; Carp, Oana

    2013-06-15

    A green template route for the synthesis of mesoscale solid ZnO spheres was ascertained. The protocol involves a double coating of the carbonaceous spheres with successive layers of zinc-containing species by alternating a non-ultrasound and ultrasound-assisted deposition, followed by calcination treatments. The composites were characterized by FTIR spectroscopy, thermal analysis, scanning electron microscopy while the obtained ZnO spheres by X-ray diffraction, Raman spectroscopy, scanning and transmission electron microscopy, N{sub 2} adsorption–desorption isotherms and photoluminescence investigations. A growth mechanism of the solid spheres is advanced based on these results. While the spheres' diameters and the mean size values of ZnO are independent on deposition order, the surface area and the external porosity are fairly dependent. The photoluminescence measurements showed interesting emission features, with emission bands in the violet to orange region. The spheres present high photocatalytical activity towards the degradation of phenol under UV irradiation, the main reaction being its mineralization. - Graphical abstract: A novel and eco-friendly methodology for the synthesis of mesoscale solid ZnO spheres was developed. The protocol involves a double coating of the starch-derived carbonaceous spheres with successive layers of zinc-containing species by alternating a non-ultrasound and ultrasound-assisted deposition, followed by calcination treatments. - Highlights: • ZnO solid spheres are obtained via a template route using carbonaceous spheres. • Two-step coatings of interchangeable order are used as deposition procedure. • The coating procedure influences the porosity and surface area. • ZnO spheres exhibited interesting visible photoluminescence properties. • Solid spheres showed photocatalytical activity in degradation of phenol.

  19. Tin(II) alkoxide hydrolysis products for use as base catalysts

    DOEpatents

    Boyle, Timothy J.

    2002-01-01

    Tin alkoxide compounds are provided with accessible electrons. The compounds are a polymeric tin alkoxide, [Sn(OCH.sub.2 C(CH.sub.3).sub.3).sub.2 ].sub.n, and the hydrolysis products Sn.sub.6 O.sub.4 (OCH.sub.2 C(CH.sub.3).sub.3).sub.4 and Sn.sub.5 O.sub.2 (OCH.sub.2 C(CH.sub.3).sub.3).sub.6. The hydrolysis products are formed by hydrolyzing the [Sn(OCH.sub.2 C(CH.sub.3).sub.3).sub.2 ].sub.n in a solvent with controlled amounts of water, between 0.1 and 2 moles of water per mole of the polymeric tin alkoxide.

  20. In Situ Observation of Directed Nanoparticle Aggregation During the Synthesis of Ordered Nanoporous Metal in Soft Templates

    SciTech Connect

    Parent, Lucas R.; Robinson, David B.; Cappillino, Patrick J.; Hartnett, Ryan J.; Abellan Baeza, Patricia; Evans, James E.; Browning, Nigel D.; Arslan, Ilke

    2014-02-11

    The prevalent approach to developing new nanomaterials is a trial and error process of iteratively altering synthesis procedures and then characterizing the resulting nanostructures. This is fundamentally limited in that the growth processes that occur during synthesis can only be inferred from the final synthetic structure. Directly observing real-time nanomaterial growth provides unprecedented insight into the relationship between synthesis conditions and product evolution, and facilitates a mechanistic approach to nanomaterial development. Here we use in situ liquid stage scanning transmission electron microscopy to observe the growth of mesoporous palladium in a solvated block copolymer (BCP) template under various synthesis conditions, and ultimately determine a refined synthesis procedure that yields ordered pores. We find that at low organic solvent (tetrahydrofuran, THF) content, the BCP assembles into a rigid, cylindrical micelle array with a high degree of short-range order, but poor long-range order. Upon slowing the THF evaporation rate using a solvent-vapor anneal step, the long-range order is greatly improved. The electron beam induces nucleation of small particles in the aqueous phase around the micelles. The small particles then flocculate and grow into denser structures that surround the micelles, forming an ordered mesoporous structure. The microscope observations revealed that template disorder can be addressed prior to reaction, and is not invariably induced by the growth process itself, allowing us to more quickly optimize the synthetic method. This work was conducted in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. The Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy under contract DE-AC05-76RL01830. This research

  1. Giant increase in the metal-enhanced fluorescence of organic molecules in nanoporous alumina templates and large molecule-specific red/blue-shift of the fluorescence peak.

    PubMed

    Sarkar, S; Kanchibotla, B; Nelson, J D; Edwards, J D; Anderson, J; Tepper, G C; Bandyopadhyay, S

    2014-10-01

    The fluorescence of organic fluorophore molecules is enhanced when they are placed in contact with certain metals (Al, Ag, Cu, Au, etc.) whose surface plasmon waves couple into the radiative modes of the molecules and increase the radiative efficiency. Here, we report a hitherto unknown size dependence of this metal-enhanced fluorescence (MEF) effect in the nanoscale. When the molecules are deposited in nanoporous anodic alumina films with exposed aluminum at the bottom of the pores, they form organic nanowires standing on aluminum nanoparticles whose plasmon waves have much larger amplitudes. This increases the MEF strongly, resulting in several orders of magnitude increase in the fluorescence intensity of the organic fluorophores. The increase in intensity shows an inverse superlinear dependence on nanowire diameter because the nanowires also act as plasmonic "waveguides" that concentrate the plasmons and increase the coupling of the plasmons with the radiative modes of the molecules. Furthermore, if the nanoporous template housing the nanowires has built-in electric fields due to space charges, a strong molecule-specific red- or blue-shift is induced in the fluorescence peak owing to a renormalization of the dipole moment of the molecule. This can be exploited to detect minute amounts of target molecules in a mixture using their optical signature (fluorescence) despite the presence of confounding background signals. It can result in a unique new technology for biosensing and chemical sensing.

  2. Laser-ignited frontal polymerization of shape-controllable poly(VI-co-AM) hydrogels based on 3D templates toward adsorption of heavy metal ions

    NASA Astrophysics Data System (ADS)

    Fan, Suzhen; Liu, Sisi; Wang, Xiao-Qiao; Wang, Cai-Feng; Chen, Su

    2016-06-01

    Given the increasing heavy metal pollution issue, fast preparation of polymeric hydrogels with excellent adsorption property toward heavy metal ions is very attractive. In this work, a series of poly( N-vinylimidazole-co-acrylamide) (poly(VI-co-AM)) hydrogels were synthesized via laser-ignited frontal polymerization (LIFP) for the first time. The dependence of frontal velocity and temperature on two factors monomer ratios and initiator concentrations was systematically investigated. Poly(VI-co-AM) hydrogels with any self-supporting shapes can be synthesized by a one-step LIFP in seconds through the application of 3D templates. These shape-persistent hydrogels are pH-responsive and exhibit excellent adsorption/desorption characteristics toward Mn(II), Zn(II), Cd(II), Ni(II), Cu(II) and Co(II) ions, and the adsorption conformed to the pseudo-second-order kinetic model. The reusability of the hydrogels toward mental ions adsorption was further researched, which suggested that the hydrogels can be reused without serious decrease in adsorption capacity. This work might open a promising strategy to facilely prepare shape-controllable hydrogels and expand the application of LIFP.

  3. Metal-assisted exfoliation (MAE): green process for transferring graphene to flexible substrates and templating of sub-nanometer plasmonic gaps (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Zaretski, Aliaksandr V.; Marin, Brandon C.; Moetazedi, Herad; Dill, Tyler J.; Jibril, Liban; Kong, Casey; Tao, Andrea R.; Lipomi, Darren J.

    2015-09-01

    This paper describes a new technique, termed "metal-assisted exfoliation," for the scalable transfer of graphene from catalytic copper foils to flexible polymeric supports. The process is amenable to roll-to-roll manufacturing, and the copper substrate can be recycled. We then demonstrate the use of single-layer graphene as a template for the formation of sub-nanometer plasmonic gaps using a scalable fabrication process called "nanoskiving." These gaps are formed between parallel gold nanowires in a process that first produces three-layer thin films with the architecture gold/single-layer graphene/gold, and then sections the composite films with an ultramicrotome. The structures produced can be treated as two gold nanowires separated along their entire lengths by an atomically thin graphene nanoribbon. Oxygen plasma etches the sandwiched graphene to a finite depth; this action produces a sub-nanometer gap near the top surface of the junction between the wires that is capable of supporting highly confined optical fields. The confinement of light is confirmed by surface-enhanced Raman spectroscopy measurements, which indicate that the enhancement of the electric field arises from the junction between the gold nanowires. These experiments demonstrate nanoskiving as a unique and easy-to-implement fabrication technique that is capable of forming sub-nanometer plasmonic gaps between parallel metallic nanostructures over long, macroscopic distances. These structures could be valuable for fundamental investigations as well as applications in plasmonics and molecular electronics.

  4. Mono- and Bis-Terpyridine-Based Dimer and Metallo-Organic Polymers as Ionic Templates for Preparation of Multi-Metallic Au Nanocluster and Nanowires.

    PubMed

    Liu, Die; Cao, Hongda; Jiang, Zhilong; Wu, Tun; Sun, Xiaoyi; Wang, Pingshan; Moorefield, Charles N; Dai, Liming; Newkome, George R

    2016-03-01

    The preparation of multi-metallic Au nanocluster and nanowires has been achieved using terpyridine-based metallo-organic polymers as multi-ionic templates through a straightforward counterion exchange with aqueous NaAuCl4 followed by a mild reduction in-situ with sodium citrate. The mild reduction of the [TpyFeTpy]2+ x 2[AuCl4]- complex, derived from [TpyFeTpy]2+ x 2Cl- 1 (tpy = 2,2':6',2"-terpyridine), led to the formation of Au nanoclusters (Au NC) with diameters ranging from 7.5-88 nm. Each Au NC alone contained multiple nanoparticles, with diameters ranging from 2.5-4.5 nm. 1,4-bis-terpyridine based metallo-oraganic polymer [-TpyFeTpy-TpyFeTpy-]n(2n+) x [Cl]2n- 2 was found to generate a multi-ionic metallo-polymer with AuCl4- as the counterion, after mild reduction with sodium citrate, resulting in irregular zigzag shaped Au nanowires (Au NW). The prepared Au NW from the di-metallic complex 3 should find applications within electronic devices. Both Au NC and NW were also found to possess excellent catalytic properties.

  5. Mono- and Bis-Terpyridine-Based Dimer and Metallo-Organic Polymers as Ionic Templates for Preparation of Multi-Metallic Au Nanocluster and Nanowires.

    PubMed

    Liu, Die; Cao, Hongda; Jiang, Zhilong; Wu, Tun; Sun, Xiaoyi; Wang, Pingshan; Moorefield, Charles N; Dai, Liming; Newkome, George R

    2016-03-01

    The preparation of multi-metallic Au nanocluster and nanowires has been achieved using terpyridine-based metallo-organic polymers as multi-ionic templates through a straightforward counterion exchange with aqueous NaAuCl4 followed by a mild reduction in-situ with sodium citrate. The mild reduction of the [TpyFeTpy]2+ x 2[AuCl4]- complex, derived from [TpyFeTpy]2+ x 2Cl- 1 (tpy = 2,2':6',2"-terpyridine), led to the formation of Au nanoclusters (Au NC) with diameters ranging from 7.5-88 nm. Each Au NC alone contained multiple nanoparticles, with diameters ranging from 2.5-4.5 nm. 1,4-bis-terpyridine based metallo-oraganic polymer [-TpyFeTpy-TpyFeTpy-]n(2n+) x [Cl]2n- 2 was found to generate a multi-ionic metallo-polymer with AuCl4- as the counterion, after mild reduction with sodium citrate, resulting in irregular zigzag shaped Au nanowires (Au NW). The prepared Au NW from the di-metallic complex 3 should find applications within electronic devices. Both Au NC and NW were also found to possess excellent catalytic properties. PMID:27455678

  6. Template Catalysis by Metal-Ligand Cooperation. C-C Bond Formation via Conjugate Addition of Non-activated Nitriles under Mild, Base-free Conditions Catalyzed by a Manganese Pincer Complex.

    PubMed

    Nerush, Alexander; Vogt, Matthias; Gellrich, Urs; Leitus, Gregory; Ben-David, Yehoshoa; Milstein, David

    2016-06-01

    The first example of a catalytic Michael addition reaction of non-activated aliphatic nitriles to α,β-unsaturated carbonyl compounds under mild, neutral conditions is reported. A new de-aromatized pyridine-based PNP pincer complex of the Earth-abundant, first-row transition metal manganese serves as the catalyst. The reaction tolerates a variety of nitriles and Michael acceptors with different steric features and acceptor strengths. Mechanistic investigations including temperature-dependent NMR spectroscopy and DFT calculations reveal that the cooperative activation of alkyl nitriles, which leads to the generation of metalated nitrile nucleophile species (α-cyano carbanion analogues), is a key step of the mechanism. The metal center is not directly involved in the catalytic bond formation but rather serves, cooperatively with the ligand, as a template for the substrate activation. This approach of "template catalysis" expands the scope of potential donors for conjugate addition reactions. PMID:27164437

  7. Synthesis and Structural Investigation of a New Bimetallic Alkoxide with the Composition Mg 2Sb 4(OC 2H 5) 16

    NASA Astrophysics Data System (ADS)

    Bemm, U.; Lashgari, K.; Norrestam, R.; Nygren, M.; Westin, G.

    1993-04-01

    The new bimetallic antimony alkoxide Mg 2Sb 4(μ 3-OEt) 2(μ-OEt) 8(OEt) 6 has been prepared by reacting Mg(OEt) 2 with an excess of Sb(OE1) 3 in a toluene-ethanol solution, and its molecular structure has been established by single crystal X-ray diffraction techniques. The compound crystallizes with the triclinic space group symmetry P1¯ . The unit cell, which contains one formula unit, has the dimensions a = 9.128(4), b = 12.168(4), c = 12.640(6) Å, α = 64.06(2)°, β = 79.96(2)°, and γ = 87.29(2)°. The derived structural model has been refined against the 3235 most significant observed X-ray reflections, collected at 170(2) K, to an R-value of 0.030. The molecular structure has a major fragment similar to that found in tetrameric alkoxides or bimetallic alkoxides with the compositions M4( OR) m and M2M'2 ( OR) n, respectively. The metal-oxygen skeleton of the fragment forms a rather rigid unit, as judged by an analysis of the determined thermal displacement parameters. The Mg 2+ ions are octahedrally coordinated by the ethoxy oxygen atoms and the Sb 3+ ions can be considered to have a trigonal bipyramidal coordination when the four ethoxy oxygen atoms and the lone pair are taken into account. Extended Hückel calculations verify that the Mg-O bonds are rather ionic, while the shorter Sb-O bond are more covalent.

  8. Vertical Carbon Nanotube Device in Nanoporous Templates

    NASA Technical Reports Server (NTRS)

    Maschmann, Matthew Ralph (Inventor); Fisher, Timothy Scott (Inventor); Sands, Timothy (Inventor); Bashir, Rashid (Inventor)

    2014-01-01

    A modified porous anodic alumina template (PAA) containing a thin CNT catalyst layer directly embedded into the pore walls. CNT synthesis using the template selectively catalyzes SWNTs and DWNTs from the embedded catalyst layer to the top PAA surface, creating a vertical CNT channel within the pores. Subsequent processing allows for easy contact metallization and adaptable functionalization of the CNTs and template for a myriad of applications.

  9. Template-assisted synthesis of III-nitride and metal-oxide nano-heterostructures using low-temperature atomic layer deposition for energy, sensing, and catalysis applications (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Biyikli, Necmi; Ozgit-Akgun, Cagla; Eren, Hamit; Haider, Ali; Uyar, Tamer; Kayaci, Fatma; Guler, Mustafa Ozgur; Garifullin, Ruslan; Okyay, Ali K.; Ulusoy, Gamze M.; Goldenberg, Eda

    2015-08-01

    Recent experimental research efforts on developing functional nanostructured III-nitride and metal-oxide materials via low-temperature atomic layer deposition (ALD) will be reviewed. Ultimate conformality, a unique propoerty of ALD process, is utilized to fabricate core-shell and hollow tubular nanostructures on various nano-templates including electrospun nanofibrous polymers, self-assembled peptide nanofibers, metallic nanowires, and multi-wall carbon nanotubes (MWCNTs). III-nitride and metal-oxide coatings were deposited on these nano-templates via thermal and plasma-enhanced ALD processes with thickness values ranging from a few mono-layers to 40 nm. Metal-oxide materials studied include ZnO, TiO2, HfO2, ZrO2, and Al2O3. Standard ALD growth recipes were modified so that precursor molecules have enough time to diffuse and penetrate within the layers/pores of the nano-template material. As a result, uniform and conformal coatings on high-surface area nano-templates were demonstrated. Substrate temperatures were kept below 200C and within the self-limiting ALD window, so that temperature-sensitive template materials preserved their integrity III-nitride coatings were applied to similar nano-templates via plasma-enhanced ALD (PEALD) technique. AlN, GaN, and InN thin-film coating recipes were optimized to achieve self-limiting growth with deposition temperatures as low as 100C. BN growth took place only for >350C, in which precursor decomposition occured and therefore growth proceeded in CVD regime. III-nitride core-shell and hollow tubular single and multi-layered nanostructures were fabricated. The resulting metal-oxide and III-nitride core-shell and hollow nano-tubular structures were used for photocatalysis, dye sensitized solar cell (DSSC), energy storage and chemical sensing applications. Significantly enhanced catalysis, solar efficiency, charge capacity and sensitivity performance are reported. Moreover, core-shell metal-oxide and III-nitride materials

  10. Porphyrins as Templates for Site-Selective Atomic Layer Deposition: Vapor Metalation and in Situ Monitoring of Island Growth.

    PubMed

    Avila, Jason R; Emery, Jonathan D; Pellin, Michael J; Martinson, Alex B F; Farha, Omar K; Hupp, Joseph T

    2016-08-10

    Examinations of enzymatic catalysts suggest one key to efficient catalytic activity is discrete size metallo clusters. Mimicking enzymatic cluster systems is synthetically challenging because conventional solution methods are prone to aggregation or require capping of the cluster, thereby limiting its catalytic activity. We introduce site-selective atomic layer deposition (ALD) on porphyrins as an alternative approach to grow isolated metal oxide islands that are spatially separated. Surface-bound tetra-acid free base porphyrins (H2TCPP) may be metalated with Mn using conventional ALD precursor exposure to induce homogeneous hydroxide synthetic handles which acts as a nucleation point for subsequent ALD MnO island growth. Analytical fitting of in situ QCM mass uptake reveals island growth to be hemispherical with a convergence radius of 1.74 nm. This growth mode is confirmed with synchrotron grazing-incidence small-angle X-ray scattering (GISAXS) measurements. Finally, we extend this approach to other ALD chemistries to demonstrate the generality of this route to discrete metallo island materials.

  11. Noble metal alloy clusters in the gas phase derived from protein templates: unusual recognition of palladium by gold.

    PubMed

    Baksi, Ananya; Pradeep, T

    2013-12-21

    Matrix assisted laser desorption ionization of a mixture of gold and palladium adducts of the protein lysozyme (Lyz) produces naked alloy clusters of the type Au24Pd(+) in the gas phase. While a lysozyme-Au adduct forms Au18(+), Au25(+), Au38(+) and Au102(+) ions in the gas phase, lysozyme-Pd alone does not form any analogous cluster. Addition of various transition metal ions (Ag(+), Pt(2+), Pd(2+), Cu(2+), Fe(2+), Ni(2+) and Cr(3+)) in the adducts contributes to drastic changes in the mass spectrum, but only palladium forms alloys in the gas phase. Besides alloy formation, palladium enhances the formation of specific single component clusters such as Au38(+). While other metal ions like Cu(2+) help forming Au25(+) selectively, Fe(2+) catalyzes the formation of Au25(+) over all other clusters. Gas phase cluster formation occurs from protein adducts where Au is in the 1+ state while Pd is in the 2+ state. The creation of alloys in the gas phase is not affected whether a physical mixture of Au and Pd adducts or a Au and Pd co-adduct is used as the precursor. The formation of Au cores and AuPd alloy cores of the kind comparable to monolayer protected clusters implies that naked clusters themselves may be nucleated in solution. PMID:24146135

  12. Noble metal alloy clusters in the gas phase derived from protein templates: unusual recognition of palladium by gold.

    PubMed

    Baksi, Ananya; Pradeep, T

    2013-12-21

    Matrix assisted laser desorption ionization of a mixture of gold and palladium adducts of the protein lysozyme (Lyz) produces naked alloy clusters of the type Au24Pd(+) in the gas phase. While a lysozyme-Au adduct forms Au18(+), Au25(+), Au38(+) and Au102(+) ions in the gas phase, lysozyme-Pd alone does not form any analogous cluster. Addition of various transition metal ions (Ag(+), Pt(2+), Pd(2+), Cu(2+), Fe(2+), Ni(2+) and Cr(3+)) in the adducts contributes to drastic changes in the mass spectrum, but only palladium forms alloys in the gas phase. Besides alloy formation, palladium enhances the formation of specific single component clusters such as Au38(+). While other metal ions like Cu(2+) help forming Au25(+) selectively, Fe(2+) catalyzes the formation of Au25(+) over all other clusters. Gas phase cluster formation occurs from protein adducts where Au is in the 1+ state while Pd is in the 2+ state. The creation of alloys in the gas phase is not affected whether a physical mixture of Au and Pd adducts or a Au and Pd co-adduct is used as the precursor. The formation of Au cores and AuPd alloy cores of the kind comparable to monolayer protected clusters implies that naked clusters themselves may be nucleated in solution.

  13. Spontaneous, Solvent-Free, Polymer-Templated, Solid-Solid Transformation of Thin Metal Films into Nanoparticles.

    PubMed

    Hernández-Cruz, Olivia; Avila-Gutierrez, Lizeth; Zolotukhin, Mikhail G; Gonzalez, Gonzalo; Monroy, B Marel; Montiel, Raúl; Vera-Graziano, Ricardo; Romero-Ibarra, Josue E; Novelo-Peralta, Omar; Massó Rojas, Felipe Alonso

    2016-09-14

    Metal nanoparticles have unusual optical, electronic, sensing, recognition, catalytic, and therapeutic properties. They are expected to form the basis of many of the technological and biological innovations of this century. A prerequisite for future applications using nanoparticles as functional entities is control of the shape, size, and homogeneity of these nanoparticles and of their interparticle spacing and arrangement on surfaces, between electrodes, or in devices. Here, we demonstrate that thin films of gold, silver, and copper sputter-deposited onto the surface of an organic polymer poly[[1,1':4',1″-terphenyl]-4,4″-diyl(2-bromo-1-carboxyethylidene)] (PTBC) undergo spontaneous solid-solid transformation into nanoparticles. Furthermore, we show that, by varying the thickness of the films, the volume-to-surface ratio of the polymer substrate, and the amount of plasticizer, it is possible to control the rate of transformation and the morphology of the nanoparticles formed. PTBC containing Au nanoparticles was found to enhance the cell adhesion and proliferation. To the best of our knowledge, our findings constitute the first experimental evidence of spontaneous, room-temperature, solid-solid transformation of metal films sputtered onto the surface of an organic polymeric substrate into nanoparticles (crystals).

  14. Porphyrins as Templates for Site-Selective Atomic Layer Deposition: Vapor Metalation and in Situ Monitoring of Island Growth.

    PubMed

    Avila, Jason R; Emery, Jonathan D; Pellin, Michael J; Martinson, Alex B F; Farha, Omar K; Hupp, Joseph T

    2016-08-10

    Examinations of enzymatic catalysts suggest one key to efficient catalytic activity is discrete size metallo clusters. Mimicking enzymatic cluster systems is synthetically challenging because conventional solution methods are prone to aggregation or require capping of the cluster, thereby limiting its catalytic activity. We introduce site-selective atomic layer deposition (ALD) on porphyrins as an alternative approach to grow isolated metal oxide islands that are spatially separated. Surface-bound tetra-acid free base porphyrins (H2TCPP) may be metalated with Mn using conventional ALD precursor exposure to induce homogeneous hydroxide synthetic handles which acts as a nucleation point for subsequent ALD MnO island growth. Analytical fitting of in situ QCM mass uptake reveals island growth to be hemispherical with a convergence radius of 1.74 nm. This growth mode is confirmed with synchrotron grazing-incidence small-angle X-ray scattering (GISAXS) measurements. Finally, we extend this approach to other ALD chemistries to demonstrate the generality of this route to discrete metallo island materials. PMID:27454741

  15. A template and catalyst-free metal-etching-oxidation method to synthesize aligned oxide nanowire arrays: NiO as an example.

    PubMed

    Wei, Zhi Peng; Arredondo, Miryam; Peng, Hai Yang; Zhang, Zhou; Guo, Dong Lai; Xing, Guo Zhong; Li, Yong Feng; Wong, Lai Mun; Wang, Shi Jie; Valanoor, Nagarajan; Wu, Tom

    2010-08-24

    Although NiO is one of the canonical functional binary oxides, there has been no report so far on the effective fabrication of aligned single crystalline NiO nanowire arrays. Here we report a novel vapor-based metal-etching-oxidation method to synthesize high-quality NiO nanowire arrays with good vertical alignment and morphology control. In this method, Ni foils are used as both the substrates and the nickel source; NiCl(2) powder serves as the additional Ni source and provides Cl(2) to initiate mild etching. No template is deliberately employed; instead a nanograined NiO scale formed on the NiO foil guides the vapor infiltration and assists the self-assembled growth of NiO nanowires via a novel process comprising simultaneous Cl(2) etching and gentle oxidation. Furthermore, using CoO nanowires and Co-doped NiO as examples, we show that this general method can be employed to produce nanowires of other oxides as well as the doped counterparts. PMID:20614899

  16. Metal-catalyzed coupling reactions on an olefin template: the total synthesis of (13E,15E,18Z,20Z)-1-hydroxypentacosa- 13,15,18,20-tetraen-11-yn-4-one 1-acetate.

    PubMed

    Organ, Michael G; Ghasemi, Haleh

    2004-02-01

    The naturally occurring ant venom (13E,15E,18Z,20Z)-1-hydroxypentacosa-13,15,18,20-tetraen-11-yn-4-one 1-acetate was synthesized stereospecifically using a series of metal-mediated cross-coupling reactions. The use of the difunctional olefin template (E)-1-chloro-2-iodoethylene as the central, pseudosymmetrical building block facilitated a fully convergent and, thus, efficient strategy to prepare this polyunsaturated natural product.

  17. Rapid enrichment of rare-earth metals by carboxymethyl cellulose-based open-cellular hydrogel adsorbent from HIPEs template.

    PubMed

    Zhu, Yongfeng; Wang, Wenbo; Zheng, Yian; Wang, Feng; Wang, Aiqin

    2016-04-20

    A series of monolithic open-cellular hydrogel adsorbents based on carboxymethylcellulose (CMC) were prepared through high internal phase emulsions (HIPEs) and used to enrich the rare-earth metals La(3+) and Ce(3+). The changes of pore structure, and the effects of pH, contact time, initial concentration on the adsorption performance were systematically studied. The results show that the as-prepared monolithic hydrogel adsorbents possess good open-cellular framework structure and have fast adsorption kinetics and high adsorption capacity for La(3+) and Ce(3+). The involved adsorption system can reach equilibrium within 30min and the maximal adsorption capacity is determined to be 384.62mg/g for La(3+) and 333.33mg/g for Ce(3+). Moreover, these porous hydrogel adsorbents show an excellent adsorptive reusability for La(3+) and Ce(3+) through five adsorption-desorption cycles. Such a pore hierarchy structure makes this monolithic open-cellular hydrogel adsorbent be an effective adsorbent for effective enrichment of La(3+) and Ce(3+) from aqueous solution. PMID:26876827

  18. Metal-organic framework-templated synthesis of magnetic nanoporous carbon as an efficient absorbent for enrichment of phenylurea herbicides.

    PubMed

    Liu, Xingli; Wang, Chun; Wu, Qiuhua; Wang, Zhi

    2015-04-22

    Nanoporous carbon with a high specific surface area and unique porous structure represents an attractive material as an adsorbent in analytical chemistry. In this study, a magnetic nanoporous carbon (MNC) was fabricated by direct carbonization of Co-based metal-organic framework in nitrogen atmosphere without using any additional carbon precursors. The MNC was used as an effective magnetic adsorbent for the extraction and enrichment of some phenylurea herbicides (monuron, isoproturon, diuron and buturon) in grape and bitter gourd samples prior to their determination by high performance liquid chromatography with ultraviolet detection. Several important experimental parameters that could influence the extraction efficiency were investigated and optimized. Under the optimum conditions, a good linearity was achieved in the concentration range of 1.0-100.0 ng g(-1) for monuron, diuron and buturon and 1.5-100.0 ng g(-1) for isoproturon with the correlation coefficients (r) larger than 0.9964. The limits of detection (S/N=3) of the method were in the range from 0.17 to 0.46 ng g(-1). The results indicated that the MNC material was stable and efficient adsorbent for the magnetic solid-phase extraction of phenylurea herbicides and would have a great application potential for the extraction and preconcentration of more organic pollutants from real samples. PMID:25819788

  19. Rapid enrichment of rare-earth metals by carboxymethyl cellulose-based open-cellular hydrogel adsorbent from HIPEs template.

    PubMed

    Zhu, Yongfeng; Wang, Wenbo; Zheng, Yian; Wang, Feng; Wang, Aiqin

    2016-04-20

    A series of monolithic open-cellular hydrogel adsorbents based on carboxymethylcellulose (CMC) were prepared through high internal phase emulsions (HIPEs) and used to enrich the rare-earth metals La(3+) and Ce(3+). The changes of pore structure, and the effects of pH, contact time, initial concentration on the adsorption performance were systematically studied. The results show that the as-prepared monolithic hydrogel adsorbents possess good open-cellular framework structure and have fast adsorption kinetics and high adsorption capacity for La(3+) and Ce(3+). The involved adsorption system can reach equilibrium within 30min and the maximal adsorption capacity is determined to be 384.62mg/g for La(3+) and 333.33mg/g for Ce(3+). Moreover, these porous hydrogel adsorbents show an excellent adsorptive reusability for La(3+) and Ce(3+) through five adsorption-desorption cycles. Such a pore hierarchy structure makes this monolithic open-cellular hydrogel adsorbent be an effective adsorbent for effective enrichment of La(3+) and Ce(3+) from aqueous solution.

  20. Identifying the Atomic-Level Effects of Metal Composition on the Structure and Catalytic Activity of Peptide-Templated Materials.

    PubMed

    Merrill, Nicholas A; McKee, Erik M; Merino, Kyle C; Drummy, Lawrence F; Lee, Sungsik; Reinhart, Benjamin; Ren, Yang; Frenkel, Anatoly I; Naik, Rajesh R; Bedford, Nicholas M; Knecht, Marc R

    2015-12-22

    Bioinspired approaches for the formation of metallic nanomaterials have been extensively employed for a diverse range of applications including diagnostics and catalysis. These materials can often be used under sustainable conditions; however, it is challenging to control the material size, morphology, and composition simultaneously. Here we have employed the R5 peptide, which forms a 3D scaffold to direct the size and linear shape of bimetallic PdAu nanomaterials for catalysis. The materials were prepared at varying Pd:Au ratios to probe optimal compositions to achieve maximal catalytic efficiency. These materials were extensively characterized at the atomic level using transmission electron microscopy, extended X-ray absorption fine structure spectroscopy, and atomic pair distribution function analysis derived from high-energy X-ray diffraction patterns to provide highly resolved structural information. The results confirmed PdAu alloy formation, but also demonstrated that significant surface structural disorder was present. The catalytic activity of the materials was studied for olefin hydrogenation, which demonstrated enhanced reactivity from the bimetallic structures. These results present a pathway to the bioinspired production of multimetallic materials with enhanced properties, which can be assessed via a suite of characterization methods to fully ascertain structure/function relationships.

  1. Metal-organic framework-templated synthesis of magnetic nanoporous carbon as an efficient absorbent for enrichment of phenylurea herbicides.

    PubMed

    Liu, Xingli; Wang, Chun; Wu, Qiuhua; Wang, Zhi

    2015-04-22

    Nanoporous carbon with a high specific surface area and unique porous structure represents an attractive material as an adsorbent in analytical chemistry. In this study, a magnetic nanoporous carbon (MNC) was fabricated by direct carbonization of Co-based metal-organic framework in nitrogen atmosphere without using any additional carbon precursors. The MNC was used as an effective magnetic adsorbent for the extraction and enrichment of some phenylurea herbicides (monuron, isoproturon, diuron and buturon) in grape and bitter gourd samples prior to their determination by high performance liquid chromatography with ultraviolet detection. Several important experimental parameters that could influence the extraction efficiency were investigated and optimized. Under the optimum conditions, a good linearity was achieved in the concentration range of 1.0-100.0 ng g(-1) for monuron, diuron and buturon and 1.5-100.0 ng g(-1) for isoproturon with the correlation coefficients (r) larger than 0.9964. The limits of detection (S/N=3) of the method were in the range from 0.17 to 0.46 ng g(-1). The results indicated that the MNC material was stable and efficient adsorbent for the magnetic solid-phase extraction of phenylurea herbicides and would have a great application potential for the extraction and preconcentration of more organic pollutants from real samples.

  2. Method for extracting metals from aqueous waste streams for long term storage

    DOEpatents

    Chaiko, D.J.

    1993-01-01

    A liquid-liquid extraction method for removing metals and hydrous metal colloids from waste streams is provided wherein said waste streams are contacted with a solvent system containing a water-in-oil microemulsion wherein the inverted micelles contain the extracted metal. A silicon alkoxide, either alone or in combination with other metal alkoxide compounds is added to the water-in-oil microemulsion, thereby allowing encapsulation of the extracted metal within a silicon oxide network. Lastly, the now-encapsulated metal is precipitated from the water-in-oil microemulsion phase to yield aggregates of metal-silicate particles having average. individual particle sizes of approximately 40 manometers.

  3. Method for extracting metals from aqueous waste streams for long term storage

    DOEpatents

    Chaiko, D.J.

    1995-03-07

    A liquid-liquid extraction method for removing metals and hydrous metal colloids from waste streams is provided wherein said waste streams are contacted with a solvent system containing a water-in-oil microemulsion wherein the inverted micelles contain the extracted metal. A silicon alkoxide, either alone or in combination with other metal alkoxide compounds is added to the water-in-oil microemulsion, thereby allowing encapsulation of the extracted metal within a silicon oxide network. Lastly, the now-encapsulated metal is precipitated from the water-in-oil microemulsion phase to yield aggregates of metal-silicate particles having average individual particle sizes of approximately 40 nanometers. 2 figs.

  4. Method for extracting metals from aqueous waste streams for long term storage

    DOEpatents

    Chaiko, David J.

    1995-01-01

    A liquid--liquid extraction method for removing metals and hydrous metal colloids from waste streams is provided wherein said waste streams are contacted with a solvent system containing a water-in-oil microemulsion wherein the inverted micelles contain the extracted metal. A silicon alkoxide, either alone or in combination with other metal alkoxide compounds is added to the water-in-oil microemulsion, thereby allowing encapsulation of the extracted metal within a silicon oxide network. Lastly, the now-encapsulated metal is precipitated from the water-in-oil microemulsion phase to yield aggregates of metal-silicate particles having average individual particle sizes of approximately 40 nanometers.

  5. Aldehyde insertion into a platinum hydride and subsequent nucleophilic attack of the alkoxide at phosphorus: Platinum-alkoxide/phosphorus-aryl metathesis

    SciTech Connect

    van Leeuwen, P.W.N.M.; Roobeek, C.F. ); Orpen, A.G. )

    1990-08-01

    Pt(Ph{sub 2}PO)(Ph{sub 2}POH){sub 2}H (1) was treated with o-(diphenylphosphino)benzaldehyde to give a cyclic platinum alkoxide (2). The latter rearranges to the new product 3 (Scheme I), containing 1-phenyl-3H-2,1-benzoxaphosphole and a phenyl group coordinated to platinum, via a nucleophilic attack at the coordinated phosphorus center by the alkoxy group, followed by a shift of a phenyl group from phosphorus to platinum. The crystal structure of 3 has been determined.

  6. From clusters to ionic complexes: structurally characterized thallium titanium double alkoxides.

    PubMed

    Boyle, Timothy J; Zechmann, Cecilia A; Alam, Todd M; Rodriguez, Mark A; Hijar, Cybele A; Scott, Brian L

    2002-02-25

    A series of sterically varied titanium alkoxides [[Ti(OR)(4)](n)(), n = 4, OR = OCH(2)CH(3) (OEt); n = 1, OCH(CH(3))(2) (OPr(i)); n = 2, OCH(2)C(CH(3))(3) (ONep); n = 1, OC(6)H(3)(CH(3))(2)-2,6 (DMP)] were reacted with a series of thallium alkoxides [[Tl(OR)](x) (x = 4, OR = OEt, ONep; n = infinity, DMP)]. The resultant products of the [Tl(mu(3)-OEt)](4)-modified [Ti(OR)(4)](n)() (OR = OEt, OPr(i), ONep) were found by X-ray analysis to be Tl(4)Ti(2)(mu-O)(mu(3)-OEt)(8)(OEt)(2) (1), Tl(4)Ti(2)(mu-O)(mu(3)-OPr(i))(5)(mu(3)-OEt)(3)(OEt)(2) (2), and TlTi(2)(mu(3)-OEt)(2)(mu-OEt)(mu-ONep)(2)(ONep)(4) (3), respectively. The reaction of [Tl(mu(3)-OEt)](4), 12HOEt, and 4[Ti(mu-ONep)ONep)(3)](2) to generate 3 in a higher yield resulted in the isolation of TlTi(2)(mu(3)-OEt)(mu(3)-ONep)(mu-OEt)(mu-ONep)(2)(ONep)(4) (4). Compounds 1 and 2 possess an octahedral (Oh) arrangement of two Ti and four Tl metal atoms around a mu-O central oxide atom (the Tl-O distance is too long to be considered a bond). For both compounds, each Ti atom adopts a distorted Oh geometry with one terminal OEt ligand. The Tl atoms are formally 4-coordinated, adopting a distorted pyramidal geometry using four mu(3)-OR (OR = OEt or OPr(i)) ligands to complete their coordination sphere. The Tl atoms reside approximately 1.4 A below the basal plane of oxygens. In contrast to these structures, both 3 and 4 utilize ONep ligands and display reduced oligomerization yielding trinuclear complexes without oxo formation. The two Ti cations are Oh, and the single Tl cation is in a formal distorted pyramidal (PYD) arrangement. If the lone pair of the Tl cations are considered in the geometry, each Tl adopts a square base pyramidal geometry. Two terminal ONep ligands are bound to each Ti with the remainder of the molecule consisting of mu(3)- and mu-ONep ligands. The reaction of [Tl(mu(3)-ONep)](4) with two equivalents of [Ti(mu-ONep)(ONep)(3)](2) also led to the isolation of the homoleptic trinuclear complex TlTi(2

  7. Redox-controlled polymerization of lactide catalyzed by bis(imino)pyridine iron bis(alkoxide) complexes.

    PubMed

    Biernesser, Ashley B; Li, Bo; Byers, Jeffery A

    2013-11-01

    Bis(imino)pyridine iron bis(alkoxide) complexes have been synthesized and utilized in the polymerization of (rac)-lactide. The activities of the catalysts were particularly sensitive to the identity of the initiating alkoxide with more electron-donating alkoxides resulting in faster polymerization rates. The reaction displayed characteristics of a living polymerization with production of polymers that exhibited low molecular weight distributions, linear relationships between molecular weight and conversion, and polymer growth observed for up to fifteen sequential additions of lactide monomer to the polymerization reaction. Mechanistic experiments revealed that iron bis(aryloxide) catalysts initiate polymerization with one alkoxide ligand, while iron bis(alkylalkoxide) catalysts initiate polymerization with both alkoxide ligands. Oxidation of an iron(II) catalyst precursor lead to a cationic iron(III) bis-alkoxide complex that was completely inactive toward lactide polymerization. When redox reactions were carried out during lactide polymerization, catalysis could be switched off and turned back on upon oxidation and reduction of the iron catalyst, respectively.

  8. Photoinduced Formation of Colloidal Silver in Nitrocellulose Solutions Containing Titanium Alkoxides

    NASA Astrophysics Data System (ADS)

    Kulak, A. I.; Branitsky, G. A.

    2016-07-01

    The study shows the possibility of photo-induced reduction of silver nitrate and formation of stable colloidal silver particles in an isopropanol-N,N-dimethylacetamide solution of titanium alkoxide (polybutyl titanate) stabilized by nitrocellulose. It is established that titanium alkoxide and the products of its partial hydrolysis in the liquid composition play the role of a photocatalyst for the reduction of silver ions; the introduction of nitric or acetic acid additives to the composition significantly increases its photosensitivity. The films deposited from the liquid composition, previously irradiated with visible or UV light, consist of hydrated titanium dioxide and nitrocellulose with incorporated colloidal silver. Thermal treatment of the films at 150-245°C leads to the decomposition of nitrocellulose and an increase in the absorption by silver particles.

  9. Fabrication of a new generation of track-etched templates and their use for the synthesis of metallic and organic nanostructures

    NASA Astrophysics Data System (ADS)

    Dauginet-De Pra, Laurence; Ferain, Etienne; Legras, Roger; Demoustier-Champagne, Sophie

    2002-11-01

    This paper reports on the realisation of nanoporous supported templates by the track-etching method. Spin-coated polycarbonate films have been irradiated by energetic heavy ions (Ar 9+, 220 MeV), UV irradiated and chemically etched in aqueous NaOH (2 N, 70 °C). The thickness of the supported templates has been varied between 200 nm and a few microns and the pore size between 15 and 100 nm. Dynamics of pore formation in these supported templates has been compared to dynamics of pore formation in classical self-supported track-etched membranes. This new generation of templates has been successfully used to electrochemically synthesise polypyrrole nanotubes and copper (Cu) nanowires. The pore size and the nanostructure morphology, providing information on the pore shape, have been studied by high resolution electron microscopy.

  10. Negative Hyperconjugation versus Electronegativity: Vibrational Spectra of Free Fluorinated Alkoxide Ions in the Gas Phase.

    PubMed

    Oomens, Jos; Berden, Giel; Morton, Thomas Hellman

    2015-06-22

    CO stretching frequencies of free, gaseous, fluorinated alkoxide ions shift substantially to the blue, relative to those of corresponding alcohols complexed with ammonia. Free α-fluorinated ions, pentafluoroethoxide and heptafluoroisopropoxide anions, display further blue shifts relative to cases with only β-fluorination, providing experimental evidence for fluorine negative hyperconjugation. DFT analysis with the atoms in molecules (AIM) method confirms an increase in CO bond order for the α-fluorinated ions, demonstrating an increase in carbonyl character for the free ions.

  11. Meerwein-Ponndorf-Verley alkynylation of aldehydes: essential modification of aluminium alkoxides for rate acceleration and asymmetric synthesis.

    PubMed

    Ooi, Takashi; Miura, Tomoya; Ohmatsu, Kohsuke; Saito, Akira; Maruoka, Keiji

    2004-11-21

    A novel carbonyl alkynylation has been accomplished based on utilization of the Meerwein-Ponndorf-Verley (MPV) reaction system. The success of the MPV alkynylation crucially depends on the discovery of the remarkable ligand acceleration effect of 2,2'-biphenol. For example, the alkynylation of chloral (2c) with the aluminium alkoxide 6(R = Ph), prepared in situ from Me(3)Al, 2,2'-biphenol and 2-methyl-4-phenyl-3-butyn-2-ol (1a) as an alkynyl source, proceeded smoothly in CH(2)Cl(2) at room temperature to give the desired propargyl alcohol 3ca in almost quantitative yield after 5 h stirring. The characteristic feature of this new transformation involving no metal alkynides can be visualized by the fact that the alkynyl group bearing keto carbonyl was transferred successfully to aldehyde carbonyl without any side reactions on keto carbonyl. Although the use of (S)-1,1[prime or minute]-bi-2-naphthol and its simple analogues was found to be unsuitable for inducing asymmetry in this reaction, design of new chiral biphenols bearing a certain flexibility of the biphenyl axis led to satisfactory results in terms of enantioselectivity as well as reactivity. PMID:15534709

  12. Templating Influence of Molecular Precursors on Pr(OH)3 Nanostructures.

    PubMed

    Hemmer, Eva; Cavelius, Christian; Huch, Volker; Mathur, Sanjay

    2015-07-01

    Four new praseodymium alkoxo and amido compounds ([Pr3(μ3-OtBu)2(μ2-OtBu)3(OtBu)4(HOtBu)2] (1), [Pr{OC(tBu)3}3(THF)] (2), [PrCl{N(SiMe3)2}2(THF)]2 (3), and [PrCl{OC(tBu)3}2(THF)]2 (4)) were synthesized and structurally characterized by single-crystal X-ray diffraction analysis. Application of these compounds in solvothermal synthesis of praseodymium oxide/hydroxide nanostructures showed their templating influence on the morphology and phase composition of the resulting solid-state materials. Differential reactivity of the chosen alkoxide ligands toward water and the different arrangements of metal-oxygen units in the studied precursor compounds strongly influenced the kinetics of hydrolysis and cross-condensation reactions as manifested in the morphological changes and phase composition of the final products. Thermal decomposition studies of 1-4 confirmed their conversion into the corresponding oxide phases. Activation of compounds 1, 2, and 4 by either a base or a stoichiometric amount of water showed the distinct influence of their chemical configuration on the obtained nanopowders: whereas 1 solely produced nanorods of Pr(OH)3, 2 predominantly formed a mixture of rod-shaped and spherical particles. The solvothermal decomposition of 4 resulted in Pr(OH)2Cl or PrOCl due to the presence of Cl ligands in the molecular precursor. The resultant materials were thoroughly characterized to demonstrate the relationship between precursor chemistry and the processing parameters that are clearly manifested in the morphology and phase of the final ceramics. PMID:26068779

  13. A silica sol-gel design strategy for nanostructured metallic materials.

    PubMed

    Warren, Scott C; Perkins, Matthew R; Adams, Ashley M; Kamperman, Marleen; Burns, Andrew A; Arora, Hitesh; Herz, Erik; Suteewong, Teeraporn; Sai, Hiroaki; Li, Zihui; Werner, Jörg; Song, Juho; Werner-Zwanziger, Ulrike; Zwanziger, Josef W; Grätzel, Michael; DiSalvo, Francis J; Wiesner, Ulrich

    2012-03-18

    Batteries, fuel cells and solar cells, among many other high-current-density devices, could benefit from the precise meso- to macroscopic structure control afforded by the silica sol-gel process. The porous materials made by silica sol-gel chemistry are typically insulators, however, which has restricted their application. Here we present a simple, yet highly versatile silica sol-gel process built around a multifunctional sol-gel precursor that is derived from the following: amino acids, hydroxy acids or peptides; a silicon alkoxide; and a metal acetate. This approach allows a wide range of biological functionalities and metals--including noble metals--to be combined into a library of sol-gel materials with a high degree of control over composition and structure. We demonstrate that the sol-gel process based on these precursors is compatible with block-copolymer self-assembly, colloidal crystal templating and the Stöber process. As a result of the exceptionally high metal content, these materials can be thermally processed to make porous nanocomposites with metallic percolation networks that have an electrical conductivity of over 1,000 S cm(-1). This improves the electrical conductivity of porous silica sol-gel nanocomposites by three orders of magnitude over existing approaches, opening applications to high-current-density devices.

  14. A metal-assisted templating route (S⁰M⁺I⁻) for fabricating thin-layer CoO covered on the channel of nanospherical-HMS with improved catalytic properties.

    PubMed

    Yang, Fu; Zhou, Shijian; Wang, Haiqing; Long, Saifu; Liu, Xianfeng; Kong, Yan

    2016-04-21

    Nanospherical hexagonal mesoporous silica (HMS) with a functional mesochannel covered with thin-layer-dispersed cobalt oxide species was directly fabricated via a novel metal-assisted templating method (S(0)M(+)I(-)). In this special method, cobalt ions would be enriched on the surface of the pore wall by physicochemical interactions among the surfactant, cobalt ions and silica. Typically, a metallomicelle template (S(0)M(+)) formed from the coordinative assembly of metal cations (Co(2+), M(+)) with neutral surfactant dodecyl amine (DDA, S(0)) would match with negatively charged silicate oligomers (I(-)) by counter-ion interactions to assemble into the Co-modified HMS nanosphere. The metallization of DDA micelles and the role of cobalt ions in the assembly process can be demonstrated. Interestingly, the addition of amounts of cobalt apparently affects the size of the HMS nanosphere. Additionally, the coverage of CoO species on the mesochannel is increased with cobalt ions coordinated on the micelles. Finally, the functional Co-HMS with dispersed catalytic active phase and improved structure exhibits a special catalytic activity (yield of ca. 65%) for direct oxidation of phenol to p-benzoquinone with the assistance of a sulfate radical stimulated from cobalt in the presence of peroxymonosulfate.

  15. Allylic and Allenic Halide Synthesis via NbCl5- and NbBr5-Mediated Alkoxide Rearrangements

    PubMed Central

    Ravikumar, P. C.; Yao, Lihua; Fleming, Fraser F.

    2009-01-01

    Addition of NbCl5, or NbBr5, to a series of magnesium, lithium, or potassium allylic or propargylic alkoxides directly provides allylic or allenic halides. Halogenation formally occurs through a metalla-halo-[3,3] rearrangement although concerted, ionic, and direct displacement mechanisms appear to operate competitively. Transposition of the olefin is equally effective for allylic alkoxides prepared by nucleophilic addition, deprotonation, or reduction. Experimentally, the niobium pentahalide halogenations are rapid, afford essentially pure E-allylic or allenic halides after extraction, and are applicable to a range of aliphatic and aromatic alcohols, aldehydes, and ketones. PMID:19739606

  16. Allylic and allenic halide synthesis via NbCl(5)- and NbBr(5)-mediated alkoxide rearrangements.

    PubMed

    Ravikumar, P C; Yao, Lihua; Fleming, Fraser F

    2009-10-01

    Addition of NbCl(5) or NbBr(5) to a series of magnesium, lithium, or potassium allylic or propargylic alkoxides directly provides allylic or allenic halides. Halogenation formally occurs through a metalla-halo-[3,3] rearrangement, although concerted, ionic, and direct displacement mechanisms appear to operate competitively. Transposition of the olefin is equally effective for allylic alkoxides prepared by nucleophilic addition, deprotonation, or reduction. Experimentally, the niobium pentahalide halogenations are rapid, afford essentially pure (E)-allylic or -allenic halides after extraction, and are applicable to a range of aliphatic and aromatic alcohols, aldehydes, and ketones. PMID:19739606

  17. Elemental Metals or Oxides Distributed on a Carbon Substrate or Self-Supported and the Manufacturing Process Using Graphite Oxide as Template

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh (Inventor)

    1999-01-01

    A process for providing elemental metals or metal oxides distributed on a carbon substrate or self-supported utilizing graphite oxide as a precursor. The graphite oxide is exposed to one or more metal chlorides to form an intermediary product comprising carbon, metal, chloride, and oxygen. This intermediary product can be further processed by direct exposure to carbonate-solutions to form a second intermediary product comprising carbon, metal carbonate, and oxygen. Either intermediary product may be further processed: a) in air to produce metal oxide; b) in an inert environment to produce metal oxide on carbon substrate; c) in a reducing environment to produce elemental metal distributed on carbon substrate. The product generally takes the shape of the carbon precursor.

  18. Programmable imprint lithography template

    DOEpatents

    Cardinale, Gregory F.; Talin, Albert A.

    2006-10-31

    A template for imprint lithography (IL) that reduces significantly template production costs by allowing the same template to be re-used for several technology generations. The template is composed of an array of spaced-apart moveable and individually addressable rods or plungers. Thus, the template can be configured to provide a desired pattern by programming the array of plungers such that certain of the plungers are in an "up" or actuated configuration. This arrangement of "up" and "down" plungers forms a pattern composed of protruding and recessed features which can then be impressed onto a polymer film coated substrate by applying a pressure to the template impressing the programmed configuration into the polymer film. The pattern impressed into the polymer film will be reproduced on the substrate by subsequent processing.

  19. Method for making monolithic metal oxide aerogels

    DOEpatents

    Droege, M.W.; Coronado, P.R.; Hair, L.M.

    1995-03-07

    Transparent, monolithic metal oxide aerogels of varying densities are produced using a method in which a metal alkoxide solution and a catalyst solution are prepared separately and reacted. The resulting hydrolyzed-condensed colloidal solution is gelled, and the wet gel is contained within a sealed, but gas permeable, containment vessel during supercritical extraction of the solvent. The present invention is especially advantageous for making metal oxides other than silica that are prone to forming opaque, cracked aerogels. 6 figs.

  20. Method for making monolithic metal oxide aerogels

    DOEpatents

    Droege, Michael W.; Coronado, Paul R.; Hair, Lucy M.

    1995-01-01

    Transparent, monolithic metal oxide aerogels of varying densities are produced using a method in which a metal alkoxide solution and a catalyst solution are prepared separately and reacted. The resulting hydrolyzed-condensed colloidal solution is gelled, and the wet gel is contained within a sealed, but gas permeable, containment vessel during supercritical extraction of the solvent. The present invention is especially advantageous for making metal oxides other than silica that are prone to forming opaque, cracked aerogels.

  1. Selective Kumada biaryl cross-coupling reaction enabled by an iron(III) alkoxide-N-heterocyclic carbene catalyst system.

    PubMed

    Chua, Yi-Yuan; Duong, Hung A

    2014-08-01

    A catalyst system comprising Fe2(O(t)Bu)6 and an N-heterocyclic carbene ligand enables efficient syntheses of (hetero)biaryls from the reactions of aryl Grignard reagents with a diverse spectrum of (hetero)aryl chlorides. Amongst the alkoxide and amide counterions investigated, tert-butoxide was the most effective in inhibiting the homocoupling of arylmagnesiums. PMID:24947849

  2. Kinetics and Mechanism of Calcium Hydroxide Conversion into Calcium Alkoxides: Implications in Heritage Conservation Using Nanolimes.

    PubMed

    Rodriguez-Navarro, Carlos; Vettori, Irene; Ruiz-Agudo, Encarnacion

    2016-05-24

    Nanolimes are alcohol dispersions of Ca(OH)2 nanoparticles used in the conservation of cultural heritage. Although it was believed that Ca(OH)2 particles were inert when dispersed in short-chain alcohols, it has been recently shown that they can undergo transformation into calcium alkoxides. Little is known, however, about the mechanism and kinetics of such a phase transformation as well as its effect on the performance of nanolimes. Here we show that Ca(OH)2 particles formed after lime slaking react with ethanol and isopropanol and partially transform (fractional conversion, α up to 0.08) into calcium ethoxide and isopropoxide, respectively. The transformation shows Arrhenius behavior, with apparent activation energy Ea of 29 ± 4 and 37 ± 6 kJ mol(-1) for Ca-ethoxide and Ca-isopropoxide conversion, respectively. High resolution transmission electron microscopy analyses of reactant and product phases show that the alkoxides replace the crystalline structure of Ca(OH)2 along specific [hkl] directions, preserving the external hexagonal (platelike) morphology of the parent phase. Textural and kinetic results reveal that this pseudomorphic replacement involves a 3D diffusion-controlled deceleratory advancement of the reaction front. The results are consistent with an interface-coupled dissolution-precipitation replacement mechanism. Analysis of the carbonation of Ca(OH)2 particles with different degree of conversion into Ca-ethoxide (α up to 0.08) and Ca-isopropoxide (α up to 0.04) exposed to air (20 °C, 80% relative humidity) reveals that Ca-alkoxides significantly reduce the rate of transformation into cementing CaCO3 and induce the formation of metastable vaterite, as opposed to stable calcite which forms in untransformed Ca(OH)2 samples. Similar effects are obtained when a commercial nanolime partially transformed into Ca-ethoxide is subjected to carbonation. Such effects may hamper/delay the strengthening or consolidation effects of nanolimes, thus having

  3. Kinetics and Mechanism of Calcium Hydroxide Conversion into Calcium Alkoxides: Implications in Heritage Conservation Using Nanolimes.

    PubMed

    Rodriguez-Navarro, Carlos; Vettori, Irene; Ruiz-Agudo, Encarnacion

    2016-05-24

    Nanolimes are alcohol dispersions of Ca(OH)2 nanoparticles used in the conservation of cultural heritage. Although it was believed that Ca(OH)2 particles were inert when dispersed in short-chain alcohols, it has been recently shown that they can undergo transformation into calcium alkoxides. Little is known, however, about the mechanism and kinetics of such a phase transformation as well as its effect on the performance of nanolimes. Here we show that Ca(OH)2 particles formed after lime slaking react with ethanol and isopropanol and partially transform (fractional conversion, α up to 0.08) into calcium ethoxide and isopropoxide, respectively. The transformation shows Arrhenius behavior, with apparent activation energy Ea of 29 ± 4 and 37 ± 6 kJ mol(-1) for Ca-ethoxide and Ca-isopropoxide conversion, respectively. High resolution transmission electron microscopy analyses of reactant and product phases show that the alkoxides replace the crystalline structure of Ca(OH)2 along specific [hkl] directions, preserving the external hexagonal (platelike) morphology of the parent phase. Textural and kinetic results reveal that this pseudomorphic replacement involves a 3D diffusion-controlled deceleratory advancement of the reaction front. The results are consistent with an interface-coupled dissolution-precipitation replacement mechanism. Analysis of the carbonation of Ca(OH)2 particles with different degree of conversion into Ca-ethoxide (α up to 0.08) and Ca-isopropoxide (α up to 0.04) exposed to air (20 °C, 80% relative humidity) reveals that Ca-alkoxides significantly reduce the rate of transformation into cementing CaCO3 and induce the formation of metastable vaterite, as opposed to stable calcite which forms in untransformed Ca(OH)2 samples. Similar effects are obtained when a commercial nanolime partially transformed into Ca-ethoxide is subjected to carbonation. Such effects may hamper/delay the strengthening or consolidation effects of nanolimes, thus having

  4. Templates, Numbers & Watercolors.

    ERIC Educational Resources Information Center

    Clemesha, David J.

    1990-01-01

    Describes how a second-grade class used large templates to draw and paint five-digit numbers. The lesson integrated artistic knowledge and vocabulary with their mathematics lesson in place value. Students learned how draftspeople use templates, and they studied number paintings by Charles Demuth and Jasper Johns. (KM)

  5. Synthesis of Industrially Relevant Carbamates towards Isocyanates using Carbon Dioxide and Organotin(IV) Alkoxides.

    PubMed

    Germain, Nicolas; Müller, Imke; Hanauer, Matthias; Paciello, Rocco A; Baumann, Robert; Trapp, Oliver; Schaub, Thomas

    2016-07-01

    A straightforward phosgene-free synthesis of aromatic isocyanates and diisocyanates is disclosed. Theoretical investigations suggested that the insertion of carbon dioxide (CO2 ) by dialkyltin(IV) dialkoxides could be used to convert aromatic amines into aromatic mono- and dicarbamates. Here we show, that methyl phenylcarbamate (MPC) from aniline using organotin(IV) dimethoxide and CO2 can be formed in high yield of up to 92 %, experimentally corroborating the predictions of density functional theory (DFT) calculations. MPC was then separated from the tin oxide residues and converted into phenyl isocyanate. Furthermore, organotin(IV) alkoxides could be regenerated from the tin oxide residues and reused, paving the way for a continuous industrial process. Extension of the scope to the synthesis of diurethanes from toluene 2,4-diamine and 4,4'-methylenedianiline could potentially allow the efficient production of industrially relevant diisocyanates. PMID:27319978

  6. Synthesis of Industrially Relevant Carbamates towards Isocyanates using Carbon Dioxide and Organotin(IV) Alkoxides.

    PubMed

    Germain, Nicolas; Müller, Imke; Hanauer, Matthias; Paciello, Rocco A; Baumann, Robert; Trapp, Oliver; Schaub, Thomas

    2016-07-01

    A straightforward phosgene-free synthesis of aromatic isocyanates and diisocyanates is disclosed. Theoretical investigations suggested that the insertion of carbon dioxide (CO2 ) by dialkyltin(IV) dialkoxides could be used to convert aromatic amines into aromatic mono- and dicarbamates. Here we show, that methyl phenylcarbamate (MPC) from aniline using organotin(IV) dimethoxide and CO2 can be formed in high yield of up to 92 %, experimentally corroborating the predictions of density functional theory (DFT) calculations. MPC was then separated from the tin oxide residues and converted into phenyl isocyanate. Furthermore, organotin(IV) alkoxides could be regenerated from the tin oxide residues and reused, paving the way for a continuous industrial process. Extension of the scope to the synthesis of diurethanes from toluene 2,4-diamine and 4,4'-methylenedianiline could potentially allow the efficient production of industrially relevant diisocyanates.

  7. Heterobimetallic dinuclear lanthanide alkoxide complexes as acid-base difunctional catalysts for transesterification.

    PubMed

    Zeng, Ruijie; Sheng, Hongting; Zhang, Yongcang; Feng, Yan; Chen, Zhi; Wang, Junfeng; Chen, Man; Zhu, Manzhou; Guo, Qingxiang

    2014-10-01

    A practical lanthanide(III)-catalyzed transesterification of carboxylic esters, weakly reactive carbonates, and much less-reactive ethyl silicate with primary and secondary alcohols was developed. Heterobimetallic dinuclear lanthanide alkoxide complexes [Ln2Na8{(OCH2CH2NMe2)}12(OH)2] (Ln = Nd (I), Sm (II), and Yb (III)) were used as highly active catalysts for this reaction. The mild reaction conditions enabled the transesterification of various substrates to proceed in good to high yield. Efficient activation of transesterification may be endowed by the above complexes as cooperative acid-base difunctional catalysts, which is proposed to be responsible for the higher reactivity in comparison with simple acid/base catalysts.

  8. Role of tetraalkyl(benzyl)ammonium alkoxides in the catalysis of the alkaline dehydrochlorination reaction

    SciTech Connect

    Shavanov, S.S.; Tolstikov, G.A.; Shutenkova, T.V.; Viktorov, G.A.

    1988-01-10

    The reaction was conducted by the action of aqueous NaOH taken as a 50% solution at a molar ratio to dichloroethane of 2:1 at 50-55 C in the 1% of catalyst on the dichloroethane. The results of the experiments indicated the rising activity of the tetra-alkyl(benzyl) ammonium alkoxides as the lipophilicity of the anion increased, which proceeds in the organic phase. Reaction was effected through a complex formed by the association of quaternary ammonium salts with a hydroxyl-containing compound, the solvation of the associated species with the organochlorine substrate, and coordination with NaOH. The reaction goes in the organic phase and on the interphase surface.

  9. Templates for Deposition of Microscopic Pointed Structures

    NASA Technical Reports Server (NTRS)

    Pugel, Diane E.

    2008-01-01

    Templates for fabricating sharply pointed microscopic peaks arranged in nearly regular planar arrays can be fabricated by a relatively inexpensive technique that has recently been demonstrated. Depending on the intended application, a semiconducting, insulating, or metallic film could be deposited on such a template by sputtering, thermal evaporation, pulsed laser deposition, or any other suitable conventional deposition technique. Pointed structures fabricated by use of these techniques may prove useful as photocathodes or field emitters in plasma television screens. Selected peaks could be removed from such structures and used individually as scanning tips in atomic force microscopy or mechanical surface profiling.

  10. Plug and drill template

    NASA Technical Reports Server (NTRS)

    Orella, S.

    1979-01-01

    Device installs plugs and then drills them after sandwich face sheets are in place. Template guides drill bit into center of each concealed plug thereby saving considerable time and fostering weight reduction with usage of smaller plugs.

  11. STAR Grantee 101 template

    EPA Science Inventory

    The presentation covers the standard Terms and Conditions, from reporting, to Human Subject research, to publication disclaimers, and offers some resources to find helpful information. Some slides are intended as a template, where project officers can enter specific information (...

  12. Tailoring silver nanoparticle construction using dendrimer templated silica networks

    NASA Astrophysics Data System (ADS)

    Liu, Xiaojun; Kakkar, Ashok

    2008-06-01

    We have examined the role of the internal environment of dendrimer templated silica networks in tailoring the construction of silver nanoparticle assemblies. Silica networks from which 3,5-dihydroxybenzyl alcohol based dendrimer templates have been completely removed, slowly wet with an aqueous solution of silver acetate. The latter then reacts with internal silica silanol groups, leading to chemisorption of silver ions, followed by the growth of silver oxide nanoparticles. Silica network constructed using generation 4 dendrimer contains residual dendrimer template, and mixes with aqueous silver acetate solution easily. Upon chemisorption, silver ions get photolytically reduced to silver metal under a stabilizing dendrimer environment, leading to the formation of silver metal nanoparticles.

  13. Ice-templated synthesis of multifunctional three dimensional graphene/noble metal nanocomposites and their mechanical, electrical, catalytic, and electromagnetic shielding properties

    PubMed Central

    Sahoo, P. K.; Aepuru, Radhamanohar; Panda, Himanshu Sekhar; Bahadur, D.

    2015-01-01

    In-situ homogeneous dispersion of noble metals in three-dimensional graphene sheets is a key tactic for producing macroscopic architecture, which is desirable for practical applications, such as electromagnetic interference shielding and catalyst. We report a one-step greener approach for developing porous architecture of 3D-graphene/noble metal (Pt and Ag) nanocomposite monoliths. The resulting graphene/noble metal nanocomposites exhibit a combination of ultralow density, excellent elasticity, and good electrical conductivity. Moreover, in order to illuminate the advantages of the 3D-graphene/noble metal nanocomposites, their electromagnetic interference (EMI) shielding and electrocatalytic performance are further investigated. The as-synthesized 3D-graphene/noble metal nanocomposites exhibit excellent EMI shielding effectiveness when compared to bare graphene; the effectiveness has an average of 28 dB in the 8.2–12.4 GHz X-band range. In the electro-oxidation of methanol, the 3D-graphene/Pt nanocomposite also exhibits significantly enhanced electrocatalytic performance and stability than compared to reduced graphene oxide/Pt and commercial Pt/C. PMID:26638827

  14. Ice-templated synthesis of multifunctional three dimensional graphene/noble metal nanocomposites and their mechanical, electrical, catalytic, and electromagnetic shielding properties

    NASA Astrophysics Data System (ADS)

    Sahoo, P. K.; Aepuru, Radhamanohar; Panda, Himanshu Sekhar; Bahadur, D.

    2015-12-01

    In-situ homogeneous dispersion of noble metals in three-dimensional graphene sheets is a key tactic for producing macroscopic architecture, which is desirable for practical applications, such as electromagnetic interference shielding and catalyst. We report a one-step greener approach for developing porous architecture of 3D-graphene/noble metal (Pt and Ag) nanocomposite monoliths. The resulting graphene/noble metal nanocomposites exhibit a combination of ultralow density, excellent elasticity, and good electrical conductivity. Moreover, in order to illuminate the advantages of the 3D-graphene/noble metal nanocomposites, their electromagnetic interference (EMI) shielding and electrocatalytic performance are further investigated. The as-synthesized 3D-graphene/noble metal nanocomposites exhibit excellent EMI shielding effectiveness when compared to bare graphene; the effectiveness has an average of 28 dB in the 8.2-12.4 GHz X-band range. In the electro-oxidation of methanol, the 3D-graphene/Pt nanocomposite also exhibits significantly enhanced electrocatalytic performance and stability than compared to reduced graphene oxide/Pt and commercial Pt/C.

  15. Molecular Level Coating for Metal Oxide Particles

    NASA Technical Reports Server (NTRS)

    McDaniel, Patricia R. (Inventor); Saint Clair, Terry L. (Inventor)

    2000-01-01

    Polymer encapsulated metal oxide particles are prepared by combining a polyamide acid in a polar aprotic solvent with a metal alkoxide solution. The polymer was imidized and the metal oxide formed simultaneously in a refluxing organic solvent. The resulting polymer-metal oxide is an intimately mixed commingled blend, possessing synergistic properties of both the polymer and preceramic metal oxide. The encapsulated metal oxide particles have multiple uses including, being useful in the production of skin lubricating creams, weather resistant paints, as a filler for paper, making ultraviolet light stable filled printing ink, being extruded into fibers or ribbons, and coatings for fibers used in the production of composite structural panels.

  16. Controlled hydrolysis synthesis and luminescence properties of uniform TiO2 spheres with different titanium alkoxides.

    PubMed

    Zhang, Cuimiao; Huo, Shuying; Shen, Shigang; Jia, Guang; Sun, Jing

    2013-06-01

    A series of uniform and well-dispersed TiO2 spheres have been successfully synthesized through a controlled hydrolysis route by using different titanium alkoxides as reactants. The types of titanium alkoxides and stirring time have an effect on the uniformity and dispersion of the TiO2 spherical particles. The addition of a small amount of salt also plays a crucial role for the formation of the monodisperse TiO2 spheres. Under ultraviolet excitation, the as-obtained Eu(3+)-doped TiO2 spheres exhibit red emission corresponding to the electric-dipole allowed 5D0-7F2 transition of Eu3+ ions, which is induced by the lack of inversion symmetry at the Eu3+ ions site. The Eu(3+)-doped TiO2 phosphors might find potential applications in the fields such as optical displays, photoelectric devices, and light-emitting diodes (LEDs).

  17. Metal-Organic Framework Templated Synthesis of Copper Azide as the Primary Explosive with Low Electrostatic Sensitivity and Excellent Initiation Ability.

    PubMed

    Wang, Qianyou; Feng, Xiao; Wang, Shan; Song, Naimeng; Chen, Yifa; Tong, Wenchao; Han, Yuzhen; Yang, Li; Wang, Bo

    2016-07-01

    A powerful yet safe primary explosive, embedded in a conductive carbon scaffold, is prepared by using a metal-organic framework as precursor. It simultaneously possesses low electrostatic sensitivity, good flame sensitivity, and excellent initiation ability. This method is simple, scalable, and provides a new platform for the development of energetic materials especially those employed in miniaturized explosive systems.

  18. Strong influence of polymer architecture on the microstructural evolution of hafnium-alkoxide-modified silazanes upon ceramization.

    PubMed

    Papendorf, Benjamin; Nonnenmacher, Katharina; Ionescu, Emanuel; Kleebe, Hans-Joachim; Riedel, Ralf

    2011-04-01

    The present study focuses on the synthesis and ceramization of novel hafnium-alkoxide-modified silazanes as well as on their microstructure evolution at high temperatures. The synthesis of hafnia-modified polymer-derived SiCN ceramic nanocomposites is performed via chemical modification of a polysilazane and of a cyclotrisilazane, followed by cross-linking and pyrolysis in argon atmosphere. Spectroscopic investigation (i.e., NMR, FTIR, and Raman) shows that the hafnium alkoxide reacts with the N-H groups of the cyclotrisilazane; in the case of polysilazane, reactions of N-H as well as Si-H groups with the alkoxide are observed. Consequently, scanning and transmission electron microscopy studies reveal that the ceramic nanocomposites obtained from cyclotrisilazane and polysilazane exhibited markedly different microstructures, which is a result of the different reaction pathways of the hafnium alkoxide with cyclotrisilazane and with polysilazane. Furthermore, the two prepared ceramic nanocomposites are unexpectedly found to exhibit extremely different high-temperature behavior with respect to decomposition and crystallization; this essential difference is found to be related to the different distribution of hafnium throughout the ceramic network in the two samples. Thus, the homogeneous distribution of hafnium observed in the polysilazane-derived ceramic leads to an enhanced thermal stability with respect to decomposition, whereas the local enrichment of hafnium within the matrix of the cyclotrisilazane-based sample induces a pronounced decomposition upon annealing at high temperatures. The results indicate that the chemistry and architecture of the precursor has a crucial effect on the microstructure of the resulting ceramic material and consequently on its high-temperature behavior.

  19. New inorganic (an)ion exchangers based on Mg-Al hydrous oxides: (alkoxide-free) sol-gel synthesis and characterisation.

    PubMed

    Chubar, Natalia

    2011-05-01

    New inorganic ion exchangers based on double Mg-Al hydrous oxides were generated via the new non-traditional sol-gel synthesis method which avoids using metal alkoxides as raw materials. Surface chemical and adsorptive properties of the final products were controlled by several ways of hydrogels and xerogels treatments which produced the materials of the layered structure, mixed hydrous oxides or amorphous adsorbents. The final adsorptive materials obtained via thermal treatment of xerogels were the layered mesoporous materials with carbonate in the interlayer space, surface abundance with hydroxylic groups and maximum adsorptive capacity to arsenate. Higher affinity of Mg-Al hydrous oxides towards H(2)AsO(4)(-) is confirmed by steep adsorption isotherms having plateau (removal capacity) at 220 mg[As]g(dw)(-1) for the best sample at pH=7, fast adsorption kinetics and little pH effect. Adsorption of arsenite, fluoride, bromate, bromide, selenate, borate by Mg-Al hydrous oxides was few times high either competitive (depending on the anion) as compare with the conventional inorganic ion exchange adsorbents. PMID:21345442

  20. Bridged bis(amidinate) ytterbium alkoxide and phenoxide: syntheses, structures, and their high activity for controlled polymerization of L-lactide and epsilon-caprolactone.

    PubMed

    Wang, Junfeng; Yao, Yingming; Zhang, Yong; Shen, Qi

    2009-01-19

    Bridged bis(amidinate) ytterbium alkoxide and phenoxide with diverse molecular structures were synthesized in high yields and confirmed by X-ray crystal structural analysis. The reaction of LYbCl(THF)(2) (L = Me(3)SiNC(Ph)N(CH(2))(3)NC(Ph)NSiMe(3)) with 1 equiv of NaOAr (ArO = 2,6-diisopropylphenoxo) afforded the mononuclear complex LYb(OAr)DME 1 with a seven-coordinated ytterbium atom surrounded by one chelating bis(amidinate) ligand, one phenoxo group, and one DME (dimethoxyethane) molecule. The same reaction with 1 equiv of NaO(i)Pr yielded the binuclear complex Yb(mu(2)-L)(2)(mu(2)-O(i)Pr)(2)Yb, 2, with two equivalent six-coordinate metal centers connected by two linked bis(amidinate)s and two O(i)Pr bridges formed via a ligand redistribution reaction that occurred during the metathesis reaction. Both 1 and 2 initiated the ring-opening polymerization of L-lactide, as well as epsilon-caprolactone (epsilon-CL), in a controlled manner with high reactivity, as indicated by a linear relationship between M(n) and conversion and by narrow molecular weight distributions (PDI = 1.15-1.25) up to 100% conversion. The differences in catalytic performance between complexes 1 and 2 are discussed.

  1. Geometries, thermodynamic properties and reactions of methylzinc alkoxide clusters studied by density functional theory calculations.

    PubMed

    Steudel, Ralf; Steudel, Yana

    2006-07-20

    Methylzinc alkoxide complexes are precursors for the preparation of nanosized zinc oxide particles, which in turn are catalysts or reagents in important industrial processes such as methanol synthesis and rubber vulcanization. We report for the first time the structures, energies, atomic charges, dipole moments, and vibrational spectra of more than 20 species of the type [(MeZnOR')n] with R' = H, Me, tBu and n = 1-6, calculated by density functional theory methods, mostly at the B3LYP/6-31+G* level of theory. For R' = Me, the global minimum structure of the tetramer (n = 4) is a highly symmetrical heterocubane but a ladder-type isomer is by only 70.9 kJ mol(-1) less stable. The corresponding trimer is most stable as a rooflike structure; a planar six-membered ring of relative energy 13.5 kJ mol(-1) corresponds to a saddle point connecting two equivalent rooflike trimer structures. All dimers form planar four-membered Zn2O2 rings whereas the monomer has a planar CZnOC backbone. A hexameric drumlike structure represents the global minimum on the potential energy hypersurface of [(MeZnOMe)6]. The enthalpies and Gibbs energies of the related dissociation reactions hexamer --> tetramer --> trimer --> dimer --> monomer as well as of a number of isomerization reactions have been calculated. The complexes [(MeZnOMe)n] (n = 1-3) form adducts with Lewis bases such as tetrahydrofuran (thf) and pyridine (py). The binding energy of py to the zinc atoms is about 65% larger than that of thf but is not large enough to break up the larger clusters. The bimolecular disproportionation of [(MeZnOMe)4] with formation of the dicubane [Zn{(MeZn)3(OMe)4}2] and Me2Zn is less endothermic than any isomerization or dissociation reaction of the heterocubane, but for steric reasons this reaction is not possible if R' = tBu. A novel reaction mechanism for the reported interconversion, disproportionation and ligand exchange reactions of zinc alkoxide complexes is proposed. PMID:16836455

  2. Double Emulsion Templated Celloidosomes

    NASA Astrophysics Data System (ADS)

    Arriaga, Laura R.; Marquez, Samantha M.; Kim, Shin-Hyun; Chang, Connie; Wilking, Jim; Monroy, Francisco; Marquez, Manuel; Weitz, David A.

    2012-02-01

    We present a novel approach for fabricating celloidosomes, which represent a hollow and spherical three-dimensional self-assembly of living cells encapsulating an aqueous core. Glass- capillary microfluidics is used to generate monodisperse water-in-oil-in-water double emulsion templates using lipids as stabilizers. Such templates allow for obtaining single but also double concentric celloidosomes. In addition, after a solvent removal step the double emulsion templates turn into monodisperse lipid vesicles, whose membrane spontaneously phase separates when choosing the adequate lipid composition, providing the adequate scaffold for fabricating Janus-celloidosomes. These structures may find applications in the development of bioreactors in which the synergistic effects of two different types of cells selectively adsorbed on one of the vesicle hemispheres may be exploited.

  3. Synthesis and thermal evolution of structure in alkoxide-derived niobium pentoxide gels

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.

    1993-01-01

    Niobium pentoxide gels in the form of transparent monoliths and powder have been synthesized from the controlled hydrolysis and polycondensation of niobium pentaethoxide under different experimental conditions using various mole ratios of Nb(OC2H5)5:H2O:C2H5OH:HCl. Alcohol acted as the mutual solvent and HCl as the deflocculating agent. In the absence of HCl, precipitation of colloidal particles was encountered on the addition of any water to the alkoxide. The gels were subjected to various thermal treatments and characterized by differential thermal analysis, thermogravimetric analysis, x-ray diffraction, and infrared spectroscopy. After drying at 400 C, the gels were amorphous to x-rays. The amorphous powder crystallized into the low-temperature orthorhombic form of Nb2O5 at approximately 500 C, which transformed irreversibly into the high-temperature monoclinic alpha-Nb2O5 between 900 to 1000 C. The kinetics of crystallization of the amorphous niobium pentoxide have been investigated by non-isothermal differential scanning calorimetry. The crystallization activation energy was determined to be 399 kJ/mol.

  4. Dual-template synthesis of N-doped macro/mesoporous carbon with an open-pore structure as a metal-free catalyst for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Li, Longjun; Wang, Chih-Liang; Liao, Jin-Yun; Manthiram, Arumugam

    2015-12-01

    Dye-sensitized solar cells (DSSCs) have attracted world-wide attention due to their low cost, high conversion efficiency, and environmental friendliness. Pt catalyst is usually used as the catalyst in the counter electrode of DSSCs due to its high electrochemical catalytic activity toward tri-iodide reduction. However, the high cost and scarcity of Pt prevent its large-scale application in DSSCs. It is highly desirable to replace Pt with low-cost catalysts made from earth-abundant elements. Here, we report a dual-template synthesis of N-doped macro/mesoporous carbon (macro/meso-NC) with an open-pore structure as the catalyst in the counter electrode of DSSCs. The catalytic activity of macro/meso-NC toward tri-iodide reduction has been tested by cyclic voltammetry (CV) and photocurrent-voltage (J-V) curves. It is found that the macro/meso-NC possesses excellent electrochemical catalytic activity with higher open-circuit voltage and cell efficiency than Pt. A high energy conversion efficiency of 7.27% has been achieved based on the metal-free macro/meso-NC, demonstrating as a promising catalyst for low-cost DSSCs.

  5. Large Area Nano-transfer Printing of Sub-50-nm Metal Nanostructures Using Low-cost Semi-flexible Hybrid Templates

    NASA Astrophysics Data System (ADS)

    Nagel, Robin D.; Haeberle, Tobias; Schmidt, Morten; Lugli, Paolo; Scarpa, Giuseppe

    2016-03-01

    In this work, we present a method for printing metal micro- and nanopatterns down to sub-50-nm feature sizes using replicated, defect-tolerant stamps made out of OrmoStamp®; material. The relevant parameters for a successful transfer over large areas were investigated and yields above 99 % have been achieved. Comparing our results to conventional nano-transfer printing using PDMS stamps, we find that the more rigid hybrid polymer used here prevents unintended transfer from interspaces between structures of large distance due to roof collapse and deformation of nano-sized structures due to lateral collapse. Yet, our stamps are flexible enough to ensure intimate contact with the underlying substrate over large areas even in the presence of defect particles. Additionally, the presented patterning technique is resist-, solvent-, and chemical-free and is therefore ideally suited for applications in organic nanoelectronics where standard nanostructuring methods can harm or destroy the organic material.

  6. Large Area Nano-transfer Printing of Sub-50-nm Metal Nanostructures Using Low-cost Semi-flexible Hybrid Templates.

    PubMed

    Nagel, Robin D; Haeberle, Tobias; Schmidt, Morten; Lugli, Paolo; Scarpa, Giuseppe

    2016-12-01

    In this work, we present a method for printing metal micro- and nanopatterns down to sub-50-nm feature sizes using replicated, defect-tolerant stamps made out of OrmoStamp®; material. The relevant parameters for a successful transfer over large areas were investigated and yields above 99 % have been achieved. Comparing our results to conventional nano-transfer printing using PDMS stamps, we find that the more rigid hybrid polymer used here prevents unintended transfer from interspaces between structures of large distance due to roof collapse and deformation of nano-sized structures due to lateral collapse. Yet, our stamps are flexible enough to ensure intimate contact with the underlying substrate over large areas even in the presence of defect particles. Additionally, the presented patterning technique is resist-, solvent-, and chemical-free and is therefore ideally suited for applications in organic nanoelectronics where standard nanostructuring methods can harm or destroy the organic material. PMID:26976429

  7. Large Area Nano-transfer Printing of Sub-50-nm Metal Nanostructures Using Low-cost Semi-flexible Hybrid Templates.

    PubMed

    Nagel, Robin D; Haeberle, Tobias; Schmidt, Morten; Lugli, Paolo; Scarpa, Giuseppe

    2016-12-01

    In this work, we present a method for printing metal micro- and nanopatterns down to sub-50-nm feature sizes using replicated, defect-tolerant stamps made out of OrmoStamp®; material. The relevant parameters for a successful transfer over large areas were investigated and yields above 99 % have been achieved. Comparing our results to conventional nano-transfer printing using PDMS stamps, we find that the more rigid hybrid polymer used here prevents unintended transfer from interspaces between structures of large distance due to roof collapse and deformation of nano-sized structures due to lateral collapse. Yet, our stamps are flexible enough to ensure intimate contact with the underlying substrate over large areas even in the presence of defect particles. Additionally, the presented patterning technique is resist-, solvent-, and chemical-free and is therefore ideally suited for applications in organic nanoelectronics where standard nanostructuring methods can harm or destroy the organic material.

  8. Biometric template revocation

    NASA Astrophysics Data System (ADS)

    Arndt, Craig M.

    2004-08-01

    Biometric are a powerful technology for identifying humans both locally and at a distance. In order to perform identification or verification biometric systems capture an image of some biometric of a user or subject. The image is then converted mathematical to representation of the person call a template. Since we know that every human in the world is different each human will have different biometric images (different fingerprints, or faces, etc.). This is what makes biometrics useful for identification. However unlike a credit card number or a password to can be given to a person and later revoked if it is compromised and biometric is with the person for life. The problem then is to develop biometric templates witch can be easily revoked and reissued which are also unique to the user and can be easily used for identification and verification. In this paper we develop and present a method to generate a set of templates which are fully unique to the individual and also revocable. By using bases set compression algorithms in an n-dimensional orthogonal space we can represent a give biometric image in an infinite number of equally valued and unique ways. The verification and biometric matching system would be presented with a given template and revocation code. The code will then representing where in the sequence of n-dimensional vectors to start the recognition.

  9. Template engaged synthesis of hollow ceria-based composites.

    PubMed

    Chen, Guozhu; Rosei, Federico; Ma, Dongling

    2015-03-19

    Hollow ceria-based composites, which consist of noble metal nanoparticles or metal oxides as a secondary component, are being studied extensively for potential applications in heterogeneous catalysis. This is due to their unique features, which exhibit the advantages of a hollow structure (e.g. high surface area and low weight), and also integrate the properties of ceria and noble metals/metal oxides. More importantly, the synergistic effect between constituents in hollow ceria-based composites has been demonstrated in various catalytic reactions. In this feature article, we summarize the state-of-the-art in the synthesis of hollow ceria-based composites, including traditional hard-templates and more recently, sacrificial-template engaged strategies, highlighting the key role of selected templates in the formation of hollow composites. In addition, the catalytic applications of hollow ceria-based composites are briefly surveyed. Finally, challenges and perspectives on future advances of hollow ceria-based composites are outlined.

  10. Environmental Learning Centers: A Template.

    ERIC Educational Resources Information Center

    Vozick, Eric

    1999-01-01

    Provides a working model, or template, for community-based environmental learning centers (ELCs). The template presents a philosophy as well as a plan for staff and administration operations, educational programming, and financial support. The template also addresses "green" construction and maintenance of buildings and grounds and includes a…

  11. Forward and reverse (retro) iron(III) or gallium(III) desferrioxamine E and ring-expanded analogues prepared using metal-templated synthesis from endo-hydroxamic acid monomers.

    PubMed

    Lifa, Tulip; Tieu, William; Hocking, Rosalie K; Codd, Rachel

    2015-04-01

    A metal-templated synthesis (MTS) approach was used to preorganize the forward endo-hydroxamic acid monomer 4-[(5-aminopentyl)(hydroxy)amino]-4-oxobutanoic acid (for-PBH) about iron(III) in a 1:3 metal/ligand ratio to furnish the iron(III) siderophore for-[Fe(DFOE)] (ferrioxamine E) following peptide coupling. Substitution of for-PBH with the reverse (retro) hydroxamic acid analogue 3-(6-amino-N-hydroxyhexanamido)propanoic acid (ret-PBH) furnished ret-[Fe(DFOE)] (ret-ferrioxamine E). As isomers, for-[Fe(DFOE)] and ret-[Fe(DFOE)] gave identical mass spectrometry signals ([M + H(+)](+), m/zcalc 654.3, m/zobs 654.3), yet for-[Fe(DFOE)] eluted in a more polar window (tR = 23.44 min) than ret-[Fe(DFOE)] (tR = 28.13 min) on a C18 reverse-phase high-performance liquid chromatography (RP-HPLC) column. for-[Ga(DFOE)] (tR = 22.99 min) and ret-[Ga(DFOE)] (tR = 28.11 min) were prepared using gallium(III) as the metal-ion template and showed the same trend for the retention time. Ring-expanded analogues of for-[Fe(DFOE)] and ret-[Fe(DFOE)] were prepared from endo-hydroxamic acid monomers with one additional methylene unit in the amine-containing region, 4-[(6-aminohexyl)(hydroxy)amino]-4-oxobutanoic acid (for-HBH) or 3-(7-amino-N-hydroxyheptanamido)propanoic acid (ret-HBH), to give the corresponding tris(homoferrioxamine E) macrocycles, for-[Fe(HHDFOE)] or ret-[Fe(HHDFOE)] ([M + H(+)](+), m/zcalc 696.3, m/zobs 696.4). The MTS reaction using a constitutional isomer of for-HBH that transposed the methylene unit to the carboxylic acid containing region, 5-[(5-aminopentyl)(hydroxy)amino]-5-oxopentanoic acid (for-PPH), gave the macrocycle for-[Fe(HPDFOE)] in a yield significantly less than that for for-[Fe(HHDFOE)], with the gallium(III) analogue for-[Ga(HPDFOE)] unable to be detected. The work demonstrates the utility and limits of MTS for the assembly of macrocyclic siderophores from endo-hydroxamic acid monomers. Indirect measures (RP-HPLC order of elution, c log P values

  12. Synthesis of High Surface Area Alumina Aerogels without the Use of Alkoxide Precursors

    SciTech Connect

    Baumann, T F; Gash, A E; Chinn, S C; Sawvel, A M; Maxwell, R S; Satcher Jr., J H

    2004-06-25

    Alumina aerogels were prepared through the addition of propylene oxide to aqueous or ethanolic solutions of hydrated aluminum salts, AlCl{sub 3} {center_dot} 6H{sub 2}O or Al(NO{sub 3}){sub 3} {center_dot} 9H{sub 2}O, followed by drying with supercritical CO{sub 2}. This technique affords low-density (60-130 kg/m{sup 3}), high surface area (600-700 m{sup 2}/g) alumina aerogel monoliths without the use of alkoxide precursors. The dried alumina aerogels were characterized using elemental analysis, high-resolution transmission electron microscopy, powder X-ray diffraction, solid state NMR, acoustic measurements and nitrogen adsorption/desorption analysis. Powder X-ray diffraction and TEM analysis indicated that the aerogel prepared from hydrated AlCl{sub 3} in water or ethanol possessed microstructures containing highly reticulated networks of pseudoboehmite fibers, 2-5 nm in diameter and of varying lengths, while the aerogels prepared from hydrated Al(NO{sub 3}){sub 3} in ethanol were amorphous with microstructures comprised of interconnected spherical particles with diameters in the 5-15 nm range. The difference in microstructure resulted in each type of aerogel displaying distinct physical and mechanical properties. In particular, the alumina aerogels with the weblike microstructure were far more mechanically robust than those with the colloidal network, based on acoustic measurements. Both types of alumina aerogels can be transformed to {gamma}-Al{sub 2}O{sub 3} through calcination at 800 C without a significant loss in surface area or monolithicity.

  13. Heterometallic alkoxides of zirconium with tin(II) or lead(II)

    SciTech Connect

    Teff, D.J.; Huffman, J.C.; Caulton, K.G.

    1996-05-08

    Syntheses of SnZr(OR){sub 6} (R = {sup i}Pr, {sup t}Bu) and PbZr(O{sup t}Bu){sub 6} are described. With Pb and the smaller ligand O{sup i}Pr, no 1:1 compound forms, but instead Pb{sub 4}Zr{sub 2}(O{sup i}Pr){sub 16} and Pb{sub 2}Zr{sub 4}(O{sup i}Pr){sub 20} are isolated. The latter two compounds are shown to have serpentine (not closo) structures with six-coordinate Zr and three- and four-coordinate Pb. Spectroscopic studies show fluxionality (including Pb site exchange) and retention of structure in aromatic solvents. Synthetic interconversions are effected with addition of the appropriate alkoxide (Pb(O{sup i}Pr){sub 2} or Zr(O{sup i}Pr){sub 4}) with the correct stoichiometry. Titanium forms no analogous compounds. Crystallographic data (both P2{sub 1}/c at {minus}174{degrees}C) for Pb{sub 4}Zr{sub 2}(O{sup i}Pr){sub 16}, a = 12.190(6) {angstrom}, b = 14.701(7) {angstrom}, c = 19.978(13) {angstrom}, and {beta} = 105.57(3){degrees} with Z = 2; for Pb{sub 2}Zr{sub 4}(O{sup i}Pr){sub 20}, {alpha} = 16.996(6) {angstrom}, b = 10.014(3) {angstrom}, c = 24.924(9) {angstrom}, and {beta} = 105.86(1){degrees} with Z = 2.

  14. Characterization of amorphous yttria layers deposited by aqueous solutions of Y-chelate alkoxides complex

    NASA Astrophysics Data System (ADS)

    Kim, Young-Soon; Lee, Yu-Ri; Kim, Byeong-Joo; Lee, Jae-Hun; Moon, Seung-Hyun; Lee, Hunju

    2015-01-01

    Crack-free amorphous yttria layers were deposited by dip coating in solutions of different Y-chelate alkoxides complex. Three Y-chelate solutions of different concentrations were prepared using yttrium acetate tetrahydrate, yttrium stearic acid as Y source materials. PEG, diethanolamine were used as chelating agents, while ethanol, methanol and tetradecane were used as solvent. Three different combinations of chelating and solvents were used to prepare solutions for Y2O3 dip coating on SUS, electropolished and non-electropolished Hastelloy C-276 substrates. The thickness of the films was varied by changing the number of dipping cycles. At an optimized condition, the substrate surface roughness (rms) value was reduced from ∼50 nm to ∼1 nm over a 10 × 10 μm2 area. After Y2O3 deposition, MgO was deposited using ion-beam assisted deposition (IBAD), then LaMnO3 (LMO) was deposited using sputtering and GdBCO was deposited using reactive co-evaporation by deposition and reaction (RCE-DR). Detailed X-ray study indicates that LMO/MgO/Y2O3 and GdBCO/LMO/MgO/Y2O3 stack films have good out-of-plane and in-plane textures with strong c-axis alignment. The critical current (Ic) of GdBCO/LMO/MgO/Y2O3 multilayer structure varied from 190 to 420 A/cm with different solutions, when measured at 77 K. These results demonstrated that amorphous yttria can be easily deposited by dip coating using Y-chelates complex as a diffusion barrier and nucleation layer.

  15. Synthesis, Radical Reactivity, and Thermochemistry of Monomeric Cu(II) Alkoxide Complexes Relevant to Cu/Radical Alcohol Oxidation Catalysis.

    PubMed

    Porter, Thomas R; Capitao, Dany; Kaminsky, Werner; Qian, Zhaoshen; Mayer, James M

    2016-06-01

    Two new monomeric Cu(II) alkoxide complexes were prepared and fully characterized as models for intermediates in copper/radical mediated alcohol oxidation catalysis: Tp(tBuR)Cu(II)OCH2CF3 with Tp(tBu) = hydro-tris(3-tert-butyl-pyrazol-1-yl)borate 1 or Tp(tBuMe) = hydro-tris(3-tert-butyl-5-methyl-pyrazol-1-yl)borate 2. These complexes were made as models for potential intermediates in enzymatic and synthetic catalytic cycles for alcohol oxidation. However, the alkoxide ligands are not readily oxidized by loss of H; instead, these complexes were found to be hydrogen atom acceptors. They oxidize the hydroxylamine TEMPOH, 2,4,6-tri-t-butylphenol, and 1,4-cyclohexadiene to the nitroxyl radical, phenoxyl radical, and benzene, with formation of HOCH2CF3 (TFE) and the Cu(I) complexes Tp(tBuR)Cu(I)-MeCN in dichloromethane/1% MeCN or 1/2 [Tp(tBuR)Cu(I)]2 in toluene. On the basis of thermodynamics and kinetics arguments, these reactions likely proceed through concerted proton-electron transfer mechanisms. Thermochemical analyses give lower limits for the "effective bond dissociation free energies (BDFE)" of the O-H bonds in 1/2[Tp(tBuR)Cu(I)]2 + TFE and upper limits for the free energies associated with alkoxide oxidations via hydrogen atom transfer (effective alkoxide α-C-H BDFEs). These values are summations of the free energies of multiple chemical steps, which include the energetically favorable formation of 1/2[Tp(tBuR)Cu(I)]2. The effective alkoxide α-C-H bonds are very weak, BDFE ≤ 38 ± 4 kcal mol(-1) for 1 and ≤44 ± 5 kcal mol(-1) for 2 (gas-phase estimates), because C-H homolysis is thermodynamically coupled to one electron transfer to Cu(II) as well as the favorable formation of the 1/2[Tp(tBuR)Cu(I)]2 dimer. Treating 1 with the H atom acceptor (t)Bu3ArO(•) did not result in the expected alkoxide oxidation to an aldehyde, but rather net 2,2,2-trifluoroethoxyl radical transfer occurred to generate an unusual 2-substituted dienone-ether product. Treating 2

  16. Mesostructured Metal Germanium Sulfide and Selenide Materials Based on the Tetrahedral [Ge 4S 10] 4- and [Ge 4Se 10] 4- Units: Surfactant Templated Three-Dimensional Disordered Frameworks Perforated with Worm Holes

    NASA Astrophysics Data System (ADS)

    Wachhold, Michael; Kasthuri Rangan, K.; Lei, Ming; Thorpe, M. F.; Billinge, Simon J. L.; Petkov, Valeri; Heising, Joy; Kanatzidis, Mercouri G.

    2000-06-01

    The polymerization of [Ge4S10]4- and [Ge4Se10]4- unit clusters with the divalent metal ions Zn2+, Cd2+, Hg2+, Ni2+, and Co2+ in the presence of various surfactant cations leads to novel mesostructured phases. The surfactants are the quaternary ammonium salts C12H25NMe3Br, C14H29NMe3Br, C16H33NMe3Br, and C18H37NMe3Br, which play the role of templates, helping to assemble a three-dimensional mesostructured metal-germanium chalcogenide framework. These materials are stoichiometric in nature and have the formula of (R-NMe3)2[MGe4Q10] (Q=S, Se). The local atomic structure was probed by X-ray diffuse scattering and pair distribution function analysis methods and indicates that the adamantane clusters stay intact while the linking metal atoms possess a tetrahedral coordination environment. A model can be derived, from the comparison of measured and simulated X-ray powder diffraction patterns, describing the structure as an amorphous three-dimensional framework consisting of adamantane [Ge4Q10]4- units that are bridged by tetrahedral coordinated M2+ cations. The network structures used in the simulations were derived from corresponding disordered structures developed for amorphous silicon. The frameworks in (R-NMe3)2[MGe4Q10] are perforated with worm hole-like tunnels, occupied by the surfactant cations, which show no long-range order. This motif is supported by transmission electron microscopy images of these materials. The pore sizes of these channels were estimated to lie in the range of 20-30 Å, depending on the appointed surfactant cation length. The framework wall thickness of ca. 10 Å is thereby independent from the surfactant molecules used. Up to 80% of the surfactant molecules can be removed by thermal degradation under vacuum without loss of mesostructural integrity. Physical, chemical, and spectroscopic properties of these materials are discussed.

  17. Bis(phosphinic)diamido yttrium amide, alkoxide, and aryloxide complexes: an evaluation of lactide ring-opening polymerization initiator efficiency.

    PubMed

    Platel, Rachel H; White, Andrew J P; Williams, Charlotte K

    2011-08-15

    The synthesis and characterization of a series of bis(phosphinic)diamido yttrium alkoxide, amide, and aryloxide initiators are reported. The new complexes are characterized using multinuclear nuclear magnetic resonance (NMR) spectroscopy, elemental analysis, and, in some cases, X-ray crystallography. The alkoxide complexes are all dimeric in both the solid state and in solution, as are the amide complexes substituted with iso-propyl or phenyl groups on the phosphorus atoms. On the other hand, increasing the steric hindrance of the phosphorus substituents (tert-butyl), enables isolation of mononuclear yttrium amide complexes with either 2,2-dimethylpropylene or ethylene diamido ligand backbones. The complex of 2,6-di-tert-butyl-4-methylphenoxide is also mononuclear. All the new complexes are efficient initiators for rac-lactide ring-opening polymerization. The polymerization kinetics are compared and pseudo first order rate constants, k(obs), determined. The polymerization control is also discussed, by monitoring the number-averaged molecular weight, M(n), and polydispersity index, PDI, obtained using gel permeation chromatography (GPC). The alkoxide complexes are the most efficient initiators, showing very high rates and good polymerization control, behavior consistent with rapid rates of initiation. The phenoxide and amide complexes are less efficient as manifest by nonlinear regions in the kinetic plots, lower values for k(obs), and reduced polymerization control. One of the mononuclear yttrium amide complexes shows heteroselectivity in the polymerization of rac-lactide; however, this effect is reduced on changing the initiating group to phenoxide or on changing the ancillary ligand diamido backbone group.

  18. Organic or organometallic template mediated clay synthesis

    DOEpatents

    Gregar, Kathleen C.; Winans, Randall E.; Botto, Robert E.

    1994-01-01

    A method for incorporating diverse Varieties of intercalants or templates directly during hydrothermal synthesis of clays such as hectorite or montmorillonite-type layer-silicate clays. For a hectorite layer-silicate clay, refluxing a gel of silica sol, magnesium hydroxide sol and lithium fluoride for two days in the presence of an organic or organometallic intercalant or template results in crystalline products containing either (a) organic dye molecules such as ethyl violet and methyl green, (b) dye molecules such as alcian blue that are based on a Cu(II)-phthalocyannine complex, or (c) transition metal complexes such as Ru(II)phenanthroline and Co(III)sepulchrate or (d) water-soluble porphyrins and metalloporphyrins. Montmorillonite-type clays are made by the method taught by U.S. Pat. No. 3,887,454 issued to Hickson, Jun. 13, 1975; however, a variety of intercalants or templates may be introduced. The intercalants or templates should have (i) water-solubility, (ii) positive charge, and (iii) thermal stability under moderately basic (pH 9-10) aqueous reflux conditions or hydrothermal pressurized conditions for the montmorillonite-type clays.

  19. Organic or organometallic template mediated clay synthesis

    DOEpatents

    Gregar, K.C.; Winans, R.E.; Botto, R.E.

    1994-05-03

    A method is described for incorporating diverse varieties of intercalates or templates directly during hydrothermal synthesis of clays such as hectorite or montmorillonite-type layer-silicate clays. For a hectorite layer-silicate clay, refluxing a gel of silica sol, magnesium hydroxide sol and lithium fluoride for two days in the presence of an organic or organometallic intercalate or template results in crystalline products containing either (a) organic dye molecules such as ethyl violet and methyl green, (b) dye molecules such as alcian blue that are based on a Cu(II)-phthalocyannine complex, or (c) transition metal complexes such as Ru(II)phenanthroline and Co(III)sepulchrate or (d) water-soluble porphyrins and metalloporphyrins. Montmorillonite-type clays are made by the method taught by U.S. Pat. No. 3,887,454 issued to Hickson, Jun. 13, 1975; however, a variety of intercalates or templates may be introduced. The intercalates or templates should have (i) water-solubility, (ii) positive charge, and (iii) thermal stability under moderately basic (pH 9-10) aqueous reflux conditions or hydrothermal pressurized conditions for the montmorillonite-type clays. 22 figures.

  20. Organic or organometallic template mediated clay synthesis

    SciTech Connect

    Gregar, K.C.; Winans, R.E.; Botto, R.E.

    1992-12-31

    A method is given for incorporating diverse varieties of intercalants or templates directly during hydrothermal synthesis of clays such as hectorite or montmorillonite-type layer-silicate clays. For a hectorite layer-silicate clay, refluxing a gel of silica sol, magnesium hydroxide sol and LiF for 2 days with an organic or organometallic intercalant or template results in crystalline products containing either (a) organic dye molecules such as ethyl violet and methyl green, (b) dye molecules such as alcian blue based on a Cu(II)-phthalocyannine complex, or (c) transition metal complexes such as Ru(II)phenanthroline and Co(III)sepulchrate or (d) water-soluble porphyrins and metalloporphyrins. Montmorillonite-type clays are made by the method taught by US patent No. 3,887,454 issued to Hickson, June 13, 1975; however, a variety of intercalants or templates may be introduced. The intercalants or templates should have water-solubility, positive charge, and thermal stability under moderately basic (pH 9-10) aqueous reflux conditions or hydrothermal pressurized conditions for the montmorillonite-type clays.

  1. Regioselective, Transition Metal-Free C-O Coupling Reactions Involving Aryne Intermediates.

    PubMed

    Dong, Yuyang; Lipschutz, Michael I; Tilley, T Don

    2016-04-01

    A new transition-metal-free synthetic method for C-O coupling between various aryl halides and alkoxides is described. This type of transformation is typically accomplished using palladium catalysts containing a specialized phosphine ligand. The reactions reported here can be performed under mild, ambient conditions using certain potassium alkoxides and a range of aryl halides, with iodide and bromide derivatives giving the best results. A likely mechanistic pathway involves the in situ generation of an aryne intermediate, and directing groups on the aryl ring inductively control regioselectivity.

  2. Template-Stripped Tunable Plasmonic Devices on Stretchable and Rollable Substrates.

    PubMed

    Yoo, Daehan; Johnson, Timothy W; Cherukulappurath, Sudhir; Norris, David J; Oh, Sang-Hyun

    2015-11-24

    We use template stripping to integrate metallic nanostructures onto flexible, stretchable, and rollable substrates. Using this approach, high-quality patterned metals that are replicated from reusable silicon templates can be directly transferred to polydimethylsiloxane (PDMS) substrates. First we produce stretchable gold nanohole arrays and show that their optical transmission spectra can be modulated by mechanical stretching. Next we fabricate stretchable arrays of gold pyramids and demonstrate a modulation of the wavelength of light resonantly scattered from the tip of the pyramid by stretching the underlying PDMS film. The use of a flexible transfer layer also enables template stripping using a cylindrical roller as a substrate. As an example, we demonstrate roller template stripping of metallic nanoholes, nanodisks, wires, and pyramids onto the cylindrical surface of a glass rod lens. These nonplanar metallic structures produced via template stripping with flexible and stretchable films can facilitate many applications in sensing, display, plasmonics, metasurfaces, and roll-to-roll fabrication.

  3. Template-Stripped Tunable Plasmonic Devices on Stretchable and Rollable Substrates.

    PubMed

    Yoo, Daehan; Johnson, Timothy W; Cherukulappurath, Sudhir; Norris, David J; Oh, Sang-Hyun

    2015-11-24

    We use template stripping to integrate metallic nanostructures onto flexible, stretchable, and rollable substrates. Using this approach, high-quality patterned metals that are replicated from reusable silicon templates can be directly transferred to polydimethylsiloxane (PDMS) substrates. First we produce stretchable gold nanohole arrays and show that their optical transmission spectra can be modulated by mechanical stretching. Next we fabricate stretchable arrays of gold pyramids and demonstrate a modulation of the wavelength of light resonantly scattered from the tip of the pyramid by stretching the underlying PDMS film. The use of a flexible transfer layer also enables template stripping using a cylindrical roller as a substrate. As an example, we demonstrate roller template stripping of metallic nanoholes, nanodisks, wires, and pyramids onto the cylindrical surface of a glass rod lens. These nonplanar metallic structures produced via template stripping with flexible and stretchable films can facilitate many applications in sensing, display, plasmonics, metasurfaces, and roll-to-roll fabrication. PMID:26402066

  4. Template-Stripped Tunable Plasmonic Devices on Stretchable and Rollable Substrates

    PubMed Central

    2015-01-01

    We use template stripping to integrate metallic nanostructures onto flexible, stretchable, and rollable substrates. Using this approach, high-quality patterned metals that are replicated from reusable silicon templates can be directly transferred to polydimethylsiloxane (PDMS) substrates. First we produce stretchable gold nanohole arrays and show that their optical transmission spectra can be modulated by mechanical stretching. Next we fabricate stretchable arrays of gold pyramids and demonstrate a modulation of the wavelength of light resonantly scattered from the tip of the pyramid by stretching the underlying PDMS film. The use of a flexible transfer layer also enables template stripping using a cylindrical roller as a substrate. As an example, we demonstrate roller template stripping of metallic nanoholes, nanodisks, wires, and pyramids onto the cylindrical surface of a glass rod lens. These nonplanar metallic structures produced via template stripping with flexible and stretchable films can facilitate many applications in sensing, display, plasmonics, metasurfaces, and roll-to-roll fabrication. PMID:26402066

  5. Biologically Inspired Flagella-Templated Silica Nanotubes

    NASA Astrophysics Data System (ADS)

    Jo, Wonjin

    The desire and need for various types of nanostructures have been met with challenges of feasibility, reproducibility, and long fabrication time. To work towards improved bottom-up methods of nanofabrication, bacterial flagella are particularly attractive bio-templates for nanotubes due to their tubular structures and small inner and outer diameters. In this work, flagella isolated from Salmonella typhimurium are used as bio-templates to fabricate silica mineralized nanotubes. The process involves as well-controlled hydrolysis and condensation reaction with aminopropyltriethoxysilane (APTES), followed by the addition of tetraethoxysilane (TEOS). By controlling the concentration of TEOS and the reaction time, a simple and precise method is developed for creating silica-mineralized flagella nanotubes (SMFNs) with various thicknesses of the silica layer. In addition, the SMFNs are further modified to multifunctional nanotubes by coating metal nanoparticles (NPs) or metal oxide NPs such as gold, palladium, and iron oxide. The metallized SMFNs are achieved through reactions including reductive metallization or oxidative hydrolysis. The results from these studies provide evidence for the complete coating of SMFNs with uniform metal NP sizes and high surface area coverage. The metallized SMFNs are found to be electrically conductive along their network structures. The current-voltage characteristics show remarkably improved electrical conductivities depending on the types of metal NPs loading and SMFN networks concentration. The biologically inspired SMFNs with metal loading will allow have controlled electrical properties that can lead to the potential of creating unique and precise nanoelectronic materials. Lastly, the randomly entangled SMFNs are characterized to demonstrate their capabilities for hydrophilic and hydrophobic surface applications.

  6. Carbon-bridged bis(phenolato)lanthanide alkoxides: syntheses, structures, and their application in the controlled polymerization of epsilon-caprolactone.

    PubMed

    Yao, Yingming; Xu, Xiaoping; Liu, Bao; Zhang, Yong; Shen, Qi; Wong, Wing-Tak

    2005-07-11

    A convenient method for the synthesis of lanthanide alkoxo complexes supported by a carbon-bridged bis(phenolate) ligand 2,2'-methylenebis(6-tert-butyl-4-methylphenoxo) (MBMP2-) is described. The reaction of (C5H5)3Nd with MBMPH2 in a 1:1 molar ratio in THF gave the bis(phenolato)lanthanide complex (C5H5)Nd(MBMP)(THF)2 (1) in a nearly quantitative yield. Complex 1 further reacted with 1 equiv of 2-propanol in THF to yield the bis(phenolato)lanthanide isopropoxide [(MBMP)2Nd(mu-OPr(i))(THF)2]2 (2) in high yield. Complex 2 can also be synthesized by the direct reaction of (C5H5)3Nd with MBMPH2 in a 1:1 molar ratio and then with 1 equiv of 2-propanol in situ in THF. Thus, the analogue bis(phenolato)lanthanide alkoxides [(MBMP)2Ln(mu-OR)(THF)2]2 [R = Pr(i), Ln = Yb (3); R = Me, Ln = Nd (4), Yb (5); R = CH2Ph, Ln = Nd (6), Yb (7)] were obtained by the reactions of (C5H5)3Ln (Ln = Nd, Yb) with MBMPH2 and then with 2-propanol, methanol, or benzyl alcohol, respectively. The ytterbium complex {[(MBMP)2Yb(THF)2]2(mu-OCH2Ph)(mu-OH)} (8) was also isolated as a byproduct. The single-crystal structural analyses of complexes 1-3 and 8 revealed that the coordination geometry around lanthanide metal can be best described as a distorted tetrahedron in complex 1 and as a distorted octahedron in complexes 2, 3, and 8. A O-H...Yb agostic interaction was observed in complex 8. Complexes 2-7 were shown to be efficient catalysts for the controlled polymerization of epsilon-caprolactone. PMID:15998042

  7. Carbon-bridged bis(phenolato)lanthanide alkoxides: syntheses, structures, and their application in the controlled polymerization of epsilon-caprolactone.

    PubMed

    Yao, Yingming; Xu, Xiaoping; Liu, Bao; Zhang, Yong; Shen, Qi; Wong, Wing-Tak

    2005-07-11

    A convenient method for the synthesis of lanthanide alkoxo complexes supported by a carbon-bridged bis(phenolate) ligand 2,2'-methylenebis(6-tert-butyl-4-methylphenoxo) (MBMP2-) is described. The reaction of (C5H5)3Nd with MBMPH2 in a 1:1 molar ratio in THF gave the bis(phenolato)lanthanide complex (C5H5)Nd(MBMP)(THF)2 (1) in a nearly quantitative yield. Complex 1 further reacted with 1 equiv of 2-propanol in THF to yield the bis(phenolato)lanthanide isopropoxide [(MBMP)2Nd(mu-OPr(i))(THF)2]2 (2) in high yield. Complex 2 can also be synthesized by the direct reaction of (C5H5)3Nd with MBMPH2 in a 1:1 molar ratio and then with 1 equiv of 2-propanol in situ in THF. Thus, the analogue bis(phenolato)lanthanide alkoxides [(MBMP)2Ln(mu-OR)(THF)2]2 [R = Pr(i), Ln = Yb (3); R = Me, Ln = Nd (4), Yb (5); R = CH2Ph, Ln = Nd (6), Yb (7)] were obtained by the reactions of (C5H5)3Ln (Ln = Nd, Yb) with MBMPH2 and then with 2-propanol, methanol, or benzyl alcohol, respectively. The ytterbium complex {[(MBMP)2Yb(THF)2]2(mu-OCH2Ph)(mu-OH)} (8) was also isolated as a byproduct. The single-crystal structural analyses of complexes 1-3 and 8 revealed that the coordination geometry around lanthanide metal can be best described as a distorted tetrahedron in complex 1 and as a distorted octahedron in complexes 2, 3, and 8. A O-H...Yb agostic interaction was observed in complex 8. Complexes 2-7 were shown to be efficient catalysts for the controlled polymerization of epsilon-caprolactone.

  8. Atomic vapour deposition (AVD) of SrBi 2Ta 2O 9 using an all alkoxide precursor

    NASA Astrophysics Data System (ADS)

    Chalker, Paul R.; Potter, Richard J.; Roberts, John L.; Jones, Anthony C.; Smith, Lesley M.; Schumacher, Marcus

    2004-12-01

    A "single-source" Sr-Ta heterometal alkoxide precursor, Sr[Ta(OEt) 5(dmae)] 2 (dmae=OCH 2CH 2NMe 2), has been used for atomic vapour deposition (AVD) of SrBi 2Ta 2O 9 (SBT). This single-source precursor is designed to alleviate the mismatch between conventional Sr and Ta sources. Strontium tantalate thin films were deposited on silicon using the Sr[Ta(OEt) 5(dmae)] 2, and the optimum temperatures for deposition of strontium tantalate with a Sr:Ta ratio of 0.5 was found to be ˜510 °C. Deposition of Bi-oxide films using Bi(mmp) 3 (mmp=OCMe 2CH 2OMe) indicates similar decomposition behaviour to the Sr-Ta alkoxide precursor, demonstrating its suitability as a complementary source of Bi for SBT. The co-incorporation of Bi and Sr within the SBT films is promoted through the deposition of bismuth oxide/strontium tantalate super lattices. After post-growth annealing the super lattices are converted to strontium bismuth tantalate thin films.

  9. Gallium hydride complexes stabilised by multidentate alkoxide ligands: precursors to thin films of Ga2O3 at low temperatures.

    PubMed

    Pugh, David; Bloor, Leanne G; Parkin, Ivan P; Carmalt, Claire J

    2012-05-01

    The donor-functionalised alkoxides {Me(3-x)N(CH(2)CH(2)O)(x)} (L(x); x = 1, 2) have been used to form gallium hydride complexes [{GaH(2)(L(1))}(2)] and [{GaH(L(2))}(2)] that are stable and isolable at room temperature. Along with a heteroleptic gallium tris(alkoxide) complex [Ga(L(1))(3)] and the dimeric complex [{GaMe(L(2))}(2)], these compounds have been used as single-source precursors for the deposition of Ga(2)O(3) by aerosol-assisted chemical vapour deposition (AACVD) with toluene as solvent. The resulting films were mostly transparent, indicating low levels of carbon contamination, and they were also mainly amorphous. However, [Ga(L(1))(3)] did contain visibly crystalline material deposited at a substrate temperature of 450 °C, by far the lowest ever observed for the CVD of gallium oxide. PMID:22461280

  10. The nature of the alkoxide group, solvent, catalyst, and concentration on the gelation and porosity of hexylene-bridged polysilsesquioxanes

    SciTech Connect

    Loy, D. A.; Small, J. H.

    2004-01-01

    Hexylene-bridged polysilsesquioxanes are hybrid organic-inorganic materials prepared by the sol-gel polymerization of 1,6-bis(trialkoxysilyl)hexane monomers: (1) R = Methyl; (2) R = Ethyl; and (3) R = n-Propyl. Previous studies showed that high surface area xerogels could be prepared from 2 with base catalyzed polymerizations while non-porous xerogels could be prepared with acidic catalysts. The object of this study was to ascertain the influences of monomer alkoxide group, solvent, catalyst, and monomer concentration on gelation time, and the properties of the resulting xerogels.This study has provided some insight into the chemical parameters that affect the ultimate structure in bridged polysilsesquioxanes. First, gelation times do not necessarily directly reflect the hydrolysis and condensation rates expected for different alkoxide groups. The collapse of porosity during the drying of hexylene-bridged polysilsesquioxanes occurs in nearly all acid-catalyzed samples, save those that form quickly due to concentration or from the methoxide monomer 1 in methanolic solution. This suggests that there may be a kinetic contribution to creating porosity in addition to the network compliance model. It would also appear that syneresis of gels during aging may be the symptom of changes resulting in increased porosity. Whatever these changes may be due to, they do not appear to significantly alter the structural composition. Experiments are underway to provide more information and test some of these hypotheses.

  11. Molecular layer deposition of aluminum alkoxide polymer films using trimethylaluminum and glycidol.

    PubMed

    Lee, Younghee; Yoon, Byunghoon; Cavanagh, Andrew S; George, Steven M

    2011-12-20

    Molecular layer deposition (MLD) of aluminum alkoxide polymer films was examined using trimethlyaluminum (TMA) and glycidol (GLY) as the reactants. Glycidol is a high vapor pressure heterobifunctional reactant with both hydroxyl and epoxy chemical functionalites. These two different functionalities help avoid "double reactions" that are common with homobifuctional reactants. A variety of techniques, including in situ Fourier transform infrared (FTIR) spectroscopy and quartz crystal microbalance (QCM) measurements, were employed to study the film growth. FTIR measurements at 100 and 125 °C observed the selective reaction of the GLY hydroxyl group with the AlCH(3) surface species during GLY exposure. Epoxy ring-opening and methyl transfer from TMA to the surface epoxy species were then monitored during TMA exposure. This epoxy ring-opening reaction is dependent on strong Lewis acid-base interactions between aluminum and oxygen. The QCM experiments observed linear growth with self-limiting surface reactions at 100-175 °C under certain growth conditions. With a sufficient purge time of 20 s after TMA and GLY exposures at 125 °C, the mass gain per cycle (MGPC) was 19.8 ng/cm(2)-cycle. The individual mass gains after the TMA and GLY exposures were also consistent with a TMA/GLY stoichiometry of 4:3 in the MLD film. This TMA/GLY stoichiometry suggests the presence of Al(2)O(2) dimeric core species. The MLD films resulting from these TMA and GLY exposures also evolved with annealing temperature to form thinner conformal porous films with increased density. Non-self-limiting growth was a problem at shorter purge times and lower temperatures. With shorter purge times of 10 s at 125 °C, the MPGC increased dramatically to 134 ng/cm(2)-cycle. The individual mass gains after the TMA and GLY exposures in the CVD regime were consistent with a TMA/GLY stoichiometry of 1:1. The MGPC decreased progressively versus purge time. This behavior was attributed to the removal of

  12. Synthesis of oligoguanylates on oligocytidylate templates. [on primitive earth

    NASA Technical Reports Server (NTRS)

    Fakhrai, H.; Van Roode, J. H. G.; Orgel, L. E.

    1981-01-01

    The influence of template length in the self-condensation of guanosine 5'-phosphorimidazole in the presence of oligocytidylate templates is investigated. Reactions were carried out with cyclic cytidine 2',3'-phosphate, oligo- or polyC, and radioactively labeled guanosine 5'-phosphorimidazolide in the presence of Zn(+2) or Pb(+2) catalyst; product yields were determined by paper chromatography, thin-layer chromatography, and high-performance liquid chromatography. In the absence of a catalytic metal or in the presence of Pb(+2), a significant template effect is observed starting with the cytidine dimer and increasing in yield up to the hexamer template. Oligomers longer than the template are observed, and are predominantly 2'-5' linked in the presence of Pb(+2) and of mixed linkages in the uncatalyzed reaction. With the zinc ion as the catalyst, the template effect is first observed with the pentamer and is maximal with the heptamer. Products are predominantly 3'-5', and only a small proportion of them are longer than the template. The importance of the demonstrated formation of molecules with up to 10 guanosine units from oligocytidines as short as the dimer on the primitive earth is noted.

  13. Templated biomimetic multifunctional coatings

    NASA Astrophysics Data System (ADS)

    Sun, Chih-Hung; Gonzalez, Adriel; Linn, Nicholas C.; Jiang, Peng; Jiang, Bin

    2008-02-01

    We report a bioinspired templating technique for fabricating multifunctional optical coatings that mimic both unique functionalities of antireflective moth eyes and superhydrophobic cicada wings. Subwavelength-structured fluoropolymer nipple arrays are created by a soft-lithography-like process. The utilization of fluoropolymers simultaneously enhances the antireflective performance and the hydrophobicity of the replicated films. The specular reflectivity matches the optical simulation using a thin-film multilayer model. The dependence of the size and the crystalline ordering of the replicated nipples on the resulting antireflective properties have also been investigated by experiment and modeling. These biomimetic materials may find important technological application in self-cleaning antireflection coatings.

  14. Dynamic template-matching-based processing for handheld landmine detector

    NASA Astrophysics Data System (ADS)

    Ho, K. C.; Gader, Paul D.

    2003-09-01

    This paper investigates the use of landmine templates in the GPR data to improve the detection accuracy for a hand-held mine detection unit. The proposed algorithm applies to the discrimination operating mode after the initial detection from the search mode. The proposed template matching-based algorithm extracts the mine templates from the data acquired during the first few sweeps, and correlates the templates from the data at subsequent sweeps to enhance the detection of landmine. The proposed technique does not have a time lag in producing detection values and a detection value is generated at each sample location. Experimental results show that the proposed template matching-based detector is able to increase the detection especially for low-metal anti-personnel mines. Based on the experiment performed over the data set collected at a test site, at 95% Pd, the proposed algorithm reduces the probability of false alarms by 66% for the low-metal anti-personnel mines and 30% for the low-metal anti-tank mines.

  15. Highly active and stereoselective zirconium and hafnium alkoxide initiators for solvent-free ring-opening polymerization of rac-lactide.

    PubMed

    Chmura, Amanda J; Davidson, Matthew G; Frankis, Catherine J; Jones, Matthew D; Lunn, Matthew D

    2008-03-21

    Under solvent-free conditions (at 130 degrees C), zirconium and hafnium amine tris(phenolate) alkoxides are extremely active, well-controlled, single-site initiators for the ring-opening polymerization of rac-lactide, yielding highly heterotactic polylactide.

  16. Inverse regioselectivity in the silylstannylation of alkynes and allenes: copper-catalyzed three-component coupling with a silylborane and a tin alkoxide.

    PubMed

    Yoshida, H; Hayashi, Y; Ito, Y; Takaki, K

    2015-06-11

    Silylstannylation of alkynes and allenes has been found to proceed by three-component coupling using a silylborane and a tin alkoxide in the presence of a Cu(I) catalyst. The regioselectivities are completely inverse to those of the conventional silylstannylation under palladium catalysis. PMID:25891313

  17. Probing the Effects of Templating on the UV and Visible Light Photocatalytic Activity of Porous Nitrogen-Modified Titania Monoliths for Dye Removal.

    PubMed

    Nursam, Natalita M; Wang, Xingdong; Tan, Jeannie Z Y; Caruso, Rachel A

    2016-07-13

    Porous nitrogen-modified titania (N-titania) monoliths with tailored morphologies were prepared using phase separation and agarose gel templating techniques. The doping and templating process were simultaneously carried out in a one-pot step using alcohol amine-assisted sol-gel chemistry. The amount of polymer used in the monoliths that were prepared using phase separation was shown to affect both the physical and optical properties: higher poly(ethylene glycol) content increased the specific surface area, porosity, and visible light absorption of the final materials. For the agarose-templated monoliths, the infiltration conditions affected the monolith morphology. A porous monolith with high surface area and the least shrinkage was obtained when the N containing alkoxide precursor was infiltrated into the agarose scaffolds at 60 °C. The effect of the diverse porous morphologies on the photocatalytic activity of N-titania was studied for the decomposition of methylene blue (MB) under visible and UV light irradiation. The highest visible light activity was achieved by the agarose-templated N-titania monolith, in part due to higher N incorporation. This sample also showed better UV activity, partly because of the higher specific surface area (up to 112 m(2) g(-1)) compared to the phase separation-induced monoliths (up to 103 m(2) g(-1)). Overall, agarose-templated, porous N-titania monoliths provided better features for effectively removing the MB contaminant. PMID:27347742

  18. Templated Synthesis of Uniform Perovskite Nanowire Arrays.

    PubMed

    Ashley, Michael J; O'Brien, Matthew N; Hedderick, Konrad R; Mason, Jarad A; Ross, Michael B; Mirkin, Chad A

    2016-08-17

    While the chemical composition of semiconducting metal halide perovskites can be precisely controlled in thin films for photovoltaic devices, the synthesis of perovskite nanostructures with tunable dimensions and composition has not been realized. Here, we describe the templated synthesis of uniform perovskite nanowires with controlled diameter (50-200 nm). Importantly, by providing three examples (CH3NH3PbI3, CH3NH3PbBr3, and Cs2SnI6), we show that this process is composition general and results in oriented nanowire arrays on transparent conductive substrates. PMID:27501464

  19. Silicon template preparation for the fabrication of thin patterned gold films via template stripping

    NASA Astrophysics Data System (ADS)

    Schmidl, G.; Dellith, J.; Dellith, A.; Teller, N.; Zopf, D.; Li, G.; Dathe, A.; Mayer, G.; Hübner, U.; Zeisberger, M.; Stranik, O.; Fritzsche, W.

    2015-12-01

    Metallic nanostructures play an important role in the vast field of modern nanophotonics, which ranges from the life sciences to biomedicine and beyond. Gold is a commonly-used and attractive material for plasmonics in the visible wavelength range, most importantly due to its chemical stability. In the present work, we focused on the different methods of plasmonic nanostructure fabrication that possess the greatest potential for cost-efficient fabrication. Initially, reusable (1 0 0) silicon templates were prepared. For this purpose, three different lithography methods (i.e. e-beam, optical, and nanoparticle lithography) were used that correspond to the desired structural scales. The application of a subsequent anisotropic crystal orientation-dependent wet etching process produced well-defined pyramidal structures in a wide variety of sizes, ranging from several microns to less than 100 nm. Finally, a 200 nm-thick gold layer was deposited by means of confocal sputtering on the silicon templates and stripped in order to obtain gold films that feature a surface replica of the initial template structure. The surface roughness that was achieved on the stripped films corresponds well with the roughness of the template used. This makes it possible to prepare cost-efficient high-quality structured films in large quantities with little effort. The gold films produced were thoroughly characterized, particularly with respect to their plasmonic response.

  20. Understanding the nucleophilic character and stability of the carbanions and alkoxides of 1-(9-anthryl)ethanol and derivatives.

    PubMed

    Ramírez, Ramsés E; García-Martínez, Cirilo; Méndez, Francisco

    2013-08-22

    The nucleophilic character and stability of the carbanions vs. alkoxides derived from 2,2,2-trifluoro-1-(9-anthryl)ethanol and 1-(9-anthryl)ethanol containing X electron-releasing and X electron-acceptor substituents attached to C-10, have been studied at the B3LYP/6-31+G(d,p) level of theory. Results analyzed in terms of the absolute gas-phase acidity, Fukui function, the local hard and soft acids and bases principle, and the molecular electrostatic potential, show that the central ring of the 9-anthryl group confers an ambident nucleophilic character and stabilizes the conjugated carbanion by electron-acceptor delocalization.

  1. Template synthesis of nanoscale materials using the membrane porosity

    NASA Astrophysics Data System (ADS)

    Piraux, L.; Dubois, S.; Demoustier-Champagne, S.

    1997-08-01

    The template strategy combined with electrodeposition techniques have been successfully used to produce nanoscale objects in the cylindrical pores of track-etched polycarbonate membranes. Using this method, nanometer-size metallic wires, conductive polymer nanotubules, superconducting nanowires and quasi-one-dimensional magnetic multilayers have been fabricated. These nanoscale materials exhibit physical properties different from those found in the bulk.

  2. Zinc oxide nano- and microfabrication from coordination-polymer templates.

    PubMed

    Liu, Xiaogang

    2009-01-01

    Hex nut: An emerging synthetic approach based on metal-organic coordination-polymer templates has been used to fabricate micro- and nanoscale crystals. By using a diverse range of molecular building blocks coupled with conventional synthetic techniques, it is possible to synthesize ZnO crystals with tailored sizes, shapes (such as hexagonal rings; see figure), and surface properties.

  3. Processing of Nanosensors Using a Sacrificial Template Approach

    NASA Technical Reports Server (NTRS)

    Biaggi-Labiosa, Azlin M.; Hunter, Gary W.

    2012-01-01

    A new microsensor fabrication approach has been demonstrated based upon the use of nanostructures as templates. The fundamental idea is that existing nanostructures, such as carbon nano tubes or biological structures, have a material structure that can be used advantageously in order to provide new sensor systems but lack the advantages of some materials to, for example, operate at high temperatures. The approach is to start with a template using nanostructures such as a carbon nanotube. This template can then be coated by an oxide material with higher temperature capabilities. Upon heating in air, the carbon nanotube template is burned off, leaving only the metal oxide nanostructure. The resulting structure has a combination of the crystal structure and surface morphology of the carbon nanotube, combined with the material durability and hightemperature- sensing properties of the metal oxide. Further, since the metal oxide nanocrystals are deposited on the carbon nanotube, after burn-off what is left is a metal oxide porous nanostructure. This makes both the interior and the exterior of this nano structured sensor available for gas species detection. This, in effect, increases the surface area available for sensing, which has been shown in the past to significantly increase sensor performance.

  4. Cloning nanocrystal morphology with soft templates

    NASA Astrophysics Data System (ADS)

    Thapa, Dev Kumar; Pandey, Anshu

    2016-08-01

    In most template directed preparative methods, while the template decides the nanostructure morphology, the structure of the template itself is a non-general outcome of its peculiar chemistry. Here we demonstrate a template mediated synthesis that overcomes this deficiency. This synthesis involves overgrowth of silica template onto a sacrificial nanocrystal. Such templates are used to copy the morphologies of gold nanorods. After template overgrowth, gold is removed and silver is regrown in the template cavity to produce a single crystal silver nanorod. This technique allows for duplicating existing nanocrystals, while also providing a quantifiable breakdown of the structure - shape interdependence.

  5. DNA-templated nanowires as sacrificial materials for creating nanocapillaries

    NASA Astrophysics Data System (ADS)

    Stewart, Jacob T.; Becerril, Hector A.; Yang, Weichun; Larsen, Megan G.; Woolley, Adam T.

    2008-08-01

    DNA has shown great promise as a template for the controlled localization of various materials and the construction of wires with nanometer-dimension cross sections. We have recently developed a strategy for fabrication of nanocapillaries, using DNA-templated nanowires as a sacrificial material. We first form metal nanowires through the selective electrochemical deposition of nickel atop a surface-aligned DNA molecule. We then deposit a thin layer of silicon dioxide on top of the DNA nanostructures. Next, we photolithographically pattern openings over the ends of the wires and etch through the silicon dioxide layer to expose the metal nanowires. Finally, we etch out the DNA-templated nickel nanowires. This process results in the formation of nanocapillaries having the same dimensions as the originally formed DNA-templated nanowires. We have characterized these DNA-templated nanocapillaries using atomic force microscopy, optical microscopy and scanning electron microscopy. These constructs have potential for application in nanofluidics, power generation, sample preconcentration, and chemical sensing.

  6. Brain templates and atlases.

    PubMed

    Evans, Alan C; Janke, Andrew L; Collins, D Louis; Baillet, Sylvain

    2012-08-15

    The core concept within the field of brain mapping is the use of a standardized, or "stereotaxic", 3D coordinate frame for data analysis and reporting of findings from neuroimaging experiments. This simple construct allows brain researchers to combine data from many subjects such that group-averaged signals, be they structural or functional, can be detected above the background noise that would swamp subtle signals from any single subject. Where the signal is robust enough to be detected in individuals, it allows for the exploration of inter-individual variance in the location of that signal. From a larger perspective, it provides a powerful medium for comparison and/or combination of brain mapping findings from different imaging modalities and laboratories around the world. Finally, it provides a framework for the creation of large-scale neuroimaging databases or "atlases" that capture the population mean and variance in anatomical or physiological metrics as a function of age or disease. However, while the above benefits are not in question at first order, there are a number of conceptual and practical challenges that introduce second-order incompatibilities among experimental data. Stereotaxic mapping requires two basic components: (i) the specification of the 3D stereotaxic coordinate space, and (ii) a mapping function that transforms a 3D brain image from "native" space, i.e. the coordinate frame of the scanner at data acquisition, to that stereotaxic space. The first component is usually expressed by the choice of a representative 3D MR image that serves as target "template" or atlas. The native image is re-sampled from native to stereotaxic space under the mapping function that may have few or many degrees of freedom, depending upon the experimental design. The optimal choice of atlas template and mapping function depend upon considerations of age, gender, hemispheric asymmetry, anatomical correspondence, spatial normalization methodology and disease

  7. Brain templates and atlases.

    PubMed

    Evans, Alan C; Janke, Andrew L; Collins, D Louis; Baillet, Sylvain

    2012-08-15

    The core concept within the field of brain mapping is the use of a standardized, or "stereotaxic", 3D coordinate frame for data analysis and reporting of findings from neuroimaging experiments. This simple construct allows brain researchers to combine data from many subjects such that group-averaged signals, be they structural or functional, can be detected above the background noise that would swamp subtle signals from any single subject. Where the signal is robust enough to be detected in individuals, it allows for the exploration of inter-individual variance in the location of that signal. From a larger perspective, it provides a powerful medium for comparison and/or combination of brain mapping findings from different imaging modalities and laboratories around the world. Finally, it provides a framework for the creation of large-scale neuroimaging databases or "atlases" that capture the population mean and variance in anatomical or physiological metrics as a function of age or disease. However, while the above benefits are not in question at first order, there are a number of conceptual and practical challenges that introduce second-order incompatibilities among experimental data. Stereotaxic mapping requires two basic components: (i) the specification of the 3D stereotaxic coordinate space, and (ii) a mapping function that transforms a 3D brain image from "native" space, i.e. the coordinate frame of the scanner at data acquisition, to that stereotaxic space. The first component is usually expressed by the choice of a representative 3D MR image that serves as target "template" or atlas. The native image is re-sampled from native to stereotaxic space under the mapping function that may have few or many degrees of freedom, depending upon the experimental design. The optimal choice of atlas template and mapping function depend upon considerations of age, gender, hemispheric asymmetry, anatomical correspondence, spatial normalization methodology and disease

  8. Growth of chalcogenide semiconductors within a nanoporous aluminum oxide template

    NASA Astrophysics Data System (ADS)

    Zelenski, Catherine Mary

    This dissertation reports investigations on the synthesis of metal chalcogenide semiconductor nanoparticles grown within the pores of a nanoporous aluminum oxide template. The template used to restrict the growth of the materials contained cylindrical pores, yielding nanoparticles with non-spherical shapes. Two classes of metal chalcogenides were studied: those with three dimensional structures and those with layered structures. Three different methods were developed and investigated for the growth of MQ compounds (M = Cd, Zn, Cu, Hg; Q = S, Te): (1) a dipping method, (2) a U-tube method, and (3) a sublimation. The dipping method produced material on the template's outer surface and within the pores only within ˜2 mum of their ends. Within the limits of the template pore size, particle size and shape could not be controlled. The U-tube method deposited multiple oval shaped particles within each pore of the template. The oval particles were polycrystalline, had sizes ranging from ˜5-120 nm, and were concentrated in only one location in the pores. Reasons for the uneven distribution of particles throughout the pores were investigated. The sublimation method only deposited material on the outer surfaces of the template, and the conditions used for the sublimation altered the morphology of the template. Layered MSsb2 compounds (M = Mo, W, Re, Ti) were prepared by the thermal decomposition of selected precursor molecules within the pores of the template. The fibers produced had the same dimensions as the pores of the template. When MoSsb2 was prepared by this method, tubules of oriented crystals were formed with multiple plugs in each tubule. When WSsb2 was prepared, more solid fibers were formed. The preparation of ReSsb2 and TiSsb2 resulted in fibers that were similar in morphology to the MoSsb2 fibers. The effect of template loading method, precursor concentration, precursor type, solvent, presence of a surfactant, and annealing temperature on morphology and

  9. Controlling Pore Geometries and Interpore Distances of Anodic Aluminum Oxide Templates via Three-Step Anodization.

    PubMed

    Lim, Jin-Hee; Wiley, John B

    2015-01-01

    Porous alumina membranes have attracted much attention because they are very useful templates for the fabrication of various nanostructures important to nanotechnology. However, there are challenges in controlling pore geometries and interpore distances in alumina templates while maintaining highly ordered hexagonal pore structures. Herein, a three-step anodization method is utilized to prepare anodic alumina templates with various pore morphologies (e.g., arched-shape, tree-like, branched-shape) and tunable interpore distances. Such structures are not found within the more traditional alumina templates fabricated by a two-step anodization of aluminum films. The range of interpore distances and pore diameters within the modified templates increases with increasing voltages. In contrast, under decreasing voltages, hexagonally ordered pores can also branch into several pores with smaller sizes and reduced interpore distances. Electrochemical growth of metal nanowires in the modified templates helps to highlight details of the pore structures and which pore channels are active.

  10. Nanowire-templated lateral epitaxial growth of non-polar group III nitrides

    DOEpatents

    Wang, George T.; Li, Qiming; Creighton, J. Randall

    2010-03-02

    A method for growing high quality, nonpolar Group III nitrides using lateral growth from Group III nitride nanowires. The method of nanowire-templated lateral epitaxial growth (NTLEG) employs crystallographically aligned, substantially vertical Group III nitride nanowire arrays grown by metal-catalyzed metal-organic chemical vapor deposition (MOCVD) as templates for the lateral growth and coalescence of virtually crack-free Group III nitride films. This method requires no patterning or separate nitride growth step.

  11. Templated Growth of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Siochik Emilie J. (Inventor)

    2007-01-01

    A method of growing carbon nanotubes uses a synthesized mesoporous si lica template with approximately cylindrical pores being formed there in. The surfaces of the pores are coated with a carbon nanotube precu rsor, and the template with the surfaces of the pores so-coated is th en heated until the carbon nanotube precursor in each pore is convert ed to a carbon nanotube.

  12. Template-directed deposition of amyloid

    NASA Astrophysics Data System (ADS)

    Ha, Chanki

    The formation of amyloid plaques in tissue is a pathological feature of many neurodegenerative diseases. Amyloid deposition, the process of amyloid plaque growth by the association of individual soluble amyloid molecules with a pre-existing amyloid template (i.e. plaque), is known to be critical for amyloid formation in vivo. In order to characterize amyloid deposition, we developed novel, synthetic amyloid templates like amyloid plaques in the human Alzheimer's brain by attaching amyloid seeds covalently onto an N-hydroxysuccinimide-activated surface. Amyloid plaques with a characteristic beta-sheet structure formed through a conformational rearrangement of soluble insulin or Abeta monomers upon interaction with the template. The amyloid deposition rate followed saturation kinetics with respect to insulin concentration in the solution. According to visualization of temporal evolution of Abeta plaque deposition on a template, it was found that mature amyloid plaques serve as a sink of soluble Abeta in a solution as well as a reservoir of small aggregates such as oligomers and protofibrils. Quantitative analysis of seeding efficiencies of three different Abeta species revealed that oligomeric forms of Abeta act more efficiently as seeds than monomers or fibrils do. Furthermore, studies on the interaction between Abeta40 and 42 showed an important role of Abeta42 in amyloid deposition. A slightly acidic condition was found to be unfavorable for amyloid plaque formation. Effects of metal ions on amyloid deposition indicated that Fe3+, but not Cu3 and Zn2+, is important for the deposition of amyloid plaques. The binding of Fe3+ to Abeta42 peptide was confirmed by using SIMS analysis. Zn2+ induced nonfibrillar amorphous aggregates, but the release of Zn2+ from Abeta42 deposits by Fe3+ triggered the formation of amyloid fibers. Effects or metal ion chelators such as ethylenediamine tetraacetic acid, deferoxamine, and clioquinol on amyloid deposition were tested to

  13. Aluminum alkoxide, amide and halide complexes supported by a bulky dipyrromethene ligand: synthesis, characterization, and preliminary ε-caprolactone polymerization activity.

    PubMed

    Gianopoulos, Christopher G; Kumar, Nishant; Zhao, Yihong; Jia, Li; Kirschbaum, Kristin; Mason, Mark R

    2016-09-21

    Aluminum halide, alkoxide and amide complexes 2-6 of the form (N,N)AlX2-nYn (n = 0, 1 and (N,N) = 1,9-dimesityl-5-phenyldipyrromethene (1)) were synthesized and characterized by NMR spectroscopy and X-ray crystallography. The in situ generated lithium salt of dipyrromethene 1 was reacted with AlX3 to afford aluminum halide complexes (N,N)AlX2 (X = Cl (2), I (3)) which were isolated as dichroic crystals. Salt metathesis reactions were employed to produce alkoxide complexes (N,N)Al(Cl)(O(t)Bu) (4) and (N,N)Al(O(t)Bu)2 (5) from compound 2. The dimethylamide complex (N,N)Al(NMe2)2 (6) was prepared by reaction of dipyrromethene 1 with [Al(NMe2)3]2. Crystallographic data revealed that the dipyrromethene is non-planar when bulky coligands are present as in compounds 3-6, while in the dichloride complex 2 the dipyrromethene is planar. Halide complexes 2 and 3 reacted with adventitious moisture in toluene to afford crystalline acid-base adducts (N,N)H·HX, (X = Cl (7), I (8)), which adopted structures reminiscent of anion receptors. Alkoxide and dimethylamide complexes 5 and 6 were also applied as precatalysts for the ring-opening polymerization of ε-caprolactone and preliminary results are reported. PMID:27484717

  14. Fabrication of DNA-templated Te and Bi2Te3 nanowires by galvanic displacement.

    PubMed

    Liu, Jianfei; Uprety, Bibek; Gyawali, Shailendra; Woolley, Adam T; Myung, Nosang V; Harb, John N

    2013-09-01

    This paper demonstrates the use of galvanic displacement to form continuous tellurium-based nanowires on DNA templates, enabling the conversion of metals, which can be deposited site-specifically, into other materials needed for device fabrication. Specifically, galvanic displacement reaction of copper and nickel nanowires is used to fabricate tellurium and bismuth telluride nanowires on λ-DNA templates. The method is simple, rapid, highly selective, and applicable to a number of different materials. In this study, continuous Ni and Cu nanowires are formed on DNA templates by seeding with Ag followed by electroless plating of the desired metal. These wires are then displaced by a galvanic displacement reaction where either Te or Bi2Te3 is deposited from an acidic solution containing HTeO2(+) ions or a combination of HTeO2(+) and Bi(3+) ions, and the metal wire is simultaneously dissolved due to oxidation. Both tellurium and bismuth telluride wires can be formed from nickel templates. In contrast, copper templates only form tellurium nanowires under the conditions considered. Therefore, the composition of the metal being displaced can be used to influence the chemistry of the resulting nanowire. Galvanic displacement of metals deposited on DNA templates has the potential to enable site-specific fabrication of a variety of materials and, thereby, make an important contribution to the advancement of useful devices via self-assembled nanotemplates.

  15. e-Stars Template Builder

    NASA Technical Reports Server (NTRS)

    Cox, Brian

    2003-01-01

    e-Stars Template Builder is a computer program that implements a concept of enabling users to rapidly gain access to information on projects of NASA's Jet Propulsion Laboratory. The information about a given project is not stored in a data base, but rather, in a network that follows the project as it develops. e-Stars Template Builder resides on a server computer, using Practical Extraction and Reporting Language (PERL) scripts to create what are called "e-STARS node templates," which are software constructs that allow for project-specific configurations. The software resides on the server and does not require specific software on the user machine except for an Internet browser. A user's computer need not be equipped with special software (other than an Internet-browser program). e-Stars Template Builder is compatible with Windows, Macintosh, and UNIX operating systems. A user invokes e-Stars Template Builder from a browser window. Operations that can be performed by the user include the creation of child processes and the addition of links and descriptions of documentation to existing pages or nodes. By means of this addition of "child processes" of nodes, a network that reflects the development of a project is generated.

  16. Biometric template transformation: a security analysis

    NASA Astrophysics Data System (ADS)

    Nagar, Abhishek; Nandakumar, Karthik; Jain, Anil K.

    2010-01-01

    One of the critical steps in designing a secure biometric system is protecting the templates of the users that are stored either in a central database or on smart cards. If a biometric template is compromised, it leads to serious security and privacy threats because unlike passwords, it is not possible for a legitimate user to revoke his biometric identifiers and switch to another set of uncompromised identifiers. One methodology for biometric template protection is the template transformation approach, where the template, consisting of the features extracted from the biometric trait, is transformed using parameters derived from a user specific password or key. Only the transformed template is stored and matching is performed directly in the transformed domain. In this paper, we formally investigate the security strength of template transformation techniques and define six metrics that facilitate a holistic security evaluation. Furthermore, we analyze the security of two wellknown template transformation techniques, namely, Biohashing and cancelable fingerprint templates based on the proposed metrics. Our analysis indicates that both these schemes are vulnerable to intrusion and linkage attacks because it is relatively easy to obtain either a close approximation of the original template (Biohashing) or a pre-image of the transformed template (cancelable fingerprints). We argue that the security strength of template transformation techniques must consider also consider the computational complexity of obtaining a complete pre-image of the transformed template in addition to the complexity of recovering the original biometric template.

  17. Quantifying the Sigma and Pi interactions between U(V) f orbitals and halide, alkyl, alkoxide, amide and ketimide ligands

    SciTech Connect

    University of California, Berkeley; Lukens, Wayne W.; Edelstein, Norman M.; Magnani, Nicola; Hayton, Trevor W.; Fortier, Skye; Seaman, Lani A.

    2013-06-20

    f Orbital bonding in actinide and lanthanide complexes is critical to their behavior in a variety of areas from separations to magnetic properties. Octahedral f1 hexahalide complexes have been extensively used to study f orbital bonding due to their simple electronic structure and extensive spectroscopic characterization. The recent expansion of this family to include alkyl, alkoxide, amide, and ketimide ligands presents the opportunity to extend this study to a wider variety of ligands. To better understand f orbital bonding in these complexes, the existing molecular orbital (MO) model was refined to include the effect of covalency on spin orbit coupling in addition to its effect on orbital angular momentum (orbital reduction). The new MO model as well as the existing MO model and the crystal field (CF) model were applied to the octahedral f1 complexes to determine the covalency and strengths of the ? and ? bonds formed by the f orbitals. When covalency is significant, MO models more precisely determined the strengths of the bonds derived from the f orbitals; however, when covalency was small, the CF model was better than either MO model. The covalency determined using the new MO model is in better agreement with both experiment and theory than that predicted by the existing MO model. The results emphasize the role played by the orbital energy in determining the strength and covalency of bonds formed by the f orbitals.

  18. Effect of Ligand Field Tuning on the SMM Behavior for Three Related Alkoxide-Bridged Dysprosium Dimers.

    PubMed

    Peng, Yan; Mereacre, Valeriu; Baniodeh, Amer; Lan, Yanhua; Schlageter, Martin; Kostakis, George E; Powell, Annie K

    2016-01-01

    The synthesis and characterization of three Dy2 compounds, [Dy2(HL1)2(NO3)4] (1), [Dy2(L2)2(NO3)4] (2), and [Dy2(HL3)2(NO3)4] (3), formed using related tripodal ligands with a central tertiary amine bearing picolyl and alkoxy arms, 2-[(2-hydroxy-ethyl)-pyridin-2-ylmethylamino]-ethanol (H2L1), 2-(bis-pyridin-2-ylmethylamino)-ethanol (HL2), and 2-(bis-pyridin-2-ylmethylamino)-propane-1,3-diol (H2L3), are reported. The compounds are rare examples of alkoxide-bridged {Dy2} complexes and display capped square antiprism coordination geometry around each Dy(III) ion. Changes in the ligand field environment around the Dy(III) ions brought about through variations in the ligand donors can be gauged from the magnetic properties, with compounds 1 and 2 showing antiparallel coupling between the Dy(III) ions and 3 showing parallel coupling. Furthermore, slow relaxation of the magnetization typical of SMM behavior could be observed for compounds 2 and 3, suggesting that small variations in the ligand field can have a significant influence on the slow relaxation processes responsible for SMM behavior of Dy(III)-based systems. PMID:26652937

  19. The effect of refluxing on the alkoxide-based sodium potassium niobate sol-gel system: Thermal and spectroscopic studies

    SciTech Connect

    Chowdhury, Anirban; Bould, Jonathan; Londesborough, Michael G.S.; Milne, Steven J.

    2011-02-15

    A study on the effects of prolonged heating under reflux conditions of up to 70 h on alkoxides of sodium, potassium and niobium dissolved in 2-methoxyethanol for the synthesis of sols of composition Na{sub 0.5}K{sub 0.5}NbO{sub 3} (NKN) has been carried out using combined thermogravimetric-Fourier transform infrared spectroscopic analyses. Extended refluxing increases the homogeneity of the Na{sub 0.5}K{sub 0.5}NbO{sub 3} (NKN) system. Spectroscopic analyses on the non-refluxed and 70 h refluxed NKN gels reveal the existence of inorganic hydrated carbonates and bicarbonates, which we propose arise from the hydration and carbonation of the samples on standing in air. The X-ray diffraction patterns of these two types of gels show orthorhombic NKN phase evolutions at higher temperatures. -- Graphical abstract: Total organic evolution plots over time for NKN dried gels obtained under different refluxing times show different thermochemical behaviours and these were investigated by thermal and spectroscopic analysis tools to find a correlation between the extent of -M-O-M- chain link formation and the amount of solvent vapour (methoxyethanol) evolution. Display Omitted Research highlights: > Prolonged refluxing of sol-gel NKN precursor solutions improves final properties of an NKN system. > An NKN process thermo-chemistry with thermal and spectroscopic analysis tools was explored. > An FTIR of NKN gels reveals tendency of NKN systems for rehydration and recarbonation on standing.

  20. Cooperation of catalysts and templates

    NASA Technical Reports Server (NTRS)

    White, D. H.; Kanavarioti, A.; Nibley, C. W.; Macklin, J. W.

    1986-01-01

    In order to understand how self-reproducing molecules could have originated on the primitive Earth or extraterrestrial bodies, it would be useful to find laboratory models of simple molecules which are able to carry out processes of catalysis and templating. Furthermore, it may be anticipated that systems in which several components are acting cooperatively to catalyze each other's synthesis will have different behavior with respect to natural selection than those of purely replicating systems. As the major focus of this work, laboratory models are devised to study the influence of short peptide catalysts on template reactions which produce oligonucleotides or additional peptides. Such catalysts could have been the earliest protoenzymes of selective advantage produced by replicating oligonucleotides. Since this is a complex problem, simpler systems are also studied which embody only one aspect at a time, such as peptide formation with and without a template, peptide catalysis of nontemplated peptide synthesis, and model reactions for replication of the type pioneered by Orgel.

  1. Salt-free synthesis of samarium-aluminum mixed-metal alkoxides: X-ray crystal structures of [[(i-Pr-O)(i-Bu)Al(mu-O-i-Pr)(2)Sm(O-i-Pr)(HO-i-Pr)](mu-O-i-Pr)](2), [(THF)(2)Sm(O-t-Bu)(2)(mu-O-t-Bu)(2)Al(i-Bu)(2)], Sm(OAr)(3)(THF)(3) (Ar = 2,4,6-Me(3)C(6)H(2)), [Nd(mu-OAr)(OAr)(2)(py)(2)](2) (Ar = 2,4,6-Me(3)C(6)H(2)), and (ArO)(3)Sm[(mu-O-t-Bu)(2)Al(2)(O-t-Bu)(4)] (Ar = 2,6-i-Pr(2)C(6)H(3)).

    PubMed

    Giesbrecht, Garth R; Gordon, John C; Clark, David L; Scott, Brian L; Watkin, John G; Young, Kenneth J

    2002-12-01

    Reaction of equimolar quantities of Sm[N(SiMe(3))(2)](3) and Al(i-Bu)(3) with 6 equiv of iso-propyl alcohol in toluene leads to the formation of the mixed-metal alkoxide complex [[(i-Pr-O)(i-Bu)Al(mu-O-i-Pr)(2)Sm(O-i-Pr)(HO-i-Pr)](mu-O-i-Pr)](2) (1). An analogous reaction between 1:1 Sm[N(SiMe(3))(2)](3)/Al(i-Bu)(3) and 6 equiv of tert-butyl alcohol, followed by addition of THF, produces the THF adduct [(THF)(2)Sm(O-t-Bu)(2)(mu-O-t-Bu)(2)Al(i-Bu)(2)] (2). Compound 1 crystallizes in the space group P1 while 2 crystallizes in space group Cmcm. Cell parameters for 1: a = 11.028(2) A, b = 12.168(2) A, c = 12.879(2) A, alpha = 82.84(1) degrees, beta = 64.88(1) degrees, gamma = 70.80(1) degrees, Z = 1. Cell parameters for 2: a = 11.304(2) A, b = 22.429(4) A, c = 15.768(2) A, Z = 4. Attempts to prepare the bulkier derivatives result in the formation of lanthanide aryloxide species only; reaction between equimolar amounts of Ln[N(SiMe(3))(2)](3) (Ln = Sm, Nd) and Al(i-Bu)(3) with 6 equiv of HO-2,4,6-Me(3)C(6)H(2), followed by the addition of THF or pyridine, yields the Lewis base adducts Sm(OAr)(3)(THF)(3) (3) and [Nd(mu-OAr)(OAr)(2)(py)(2)](2) (4). Compound 3 crystallizes in the space group Pbca while 4 crystallizes in space group P2(1)/c. Cell parameters for 3: a = 16.5822(9) A, b = 15.5668(9) A, c = 29.902(2) A, Z = 8. Cell parameters for 4: a = 13.4496(8) A, b = 20.034(1) A, c = 16.206(1) A, beta = 113.782(1) degrees, Z = 2. Reaction of Al(2)(O-t-Bu)(6) with [Sm(OAr)(3)](2) (Ar = 2,6-i-Pr(2)C(6)H(3)) yields the adduct (ArO)(3)Sm[(mu-O-t-Bu)(2)Al(2)(O-t-Bu)(4)] (5), which crystallizes in the space group P2(1)/n. Cell parameters for 5: a = 14.0960(7) A, b = 27.3037(15) A, c = 16.7893(9) A, beta = 92.216(1) degrees, Z = 4. PMID:12444780

  2. Wide band gap semiconductor templates

    DOEpatents

    Arendt, Paul N.; Stan, Liliana; Jia, Quanxi; DePaula, Raymond F.; Usov, Igor O.

    2010-12-14

    The present invention relates to a thin film structure based on an epitaxial (111)-oriented rare earth-Group IVB oxide on the cubic (001) MgO terminated surface and the ion-beam-assisted deposition ("IBAD") techniques that are amendable to be over coated by semiconductors with hexagonal crystal structures. The IBAD magnesium oxide ("MgO") technology, in conjunction with certain template materials, is used to fabricate the desired thin film array. Similarly, IBAD MgO with appropriate template layers can be used for semiconductors with cubic type crystal structures.

  3. Virus Assemblies as Templates for Nanocircuits

    SciTech Connect

    James N Culver; Michael T Harris

    2011-08-31

    The goals of this project were directed at the identification and characterization of bio-mineralization processes and patterning methods for the development of nano scale materials and structures with novel energy and conductive traits. This project utilized a simple plant virus as a model template to investigate methods to attach and coat metals and other inorganic compounds onto biologically based nanotemplates. Accomplishments include: the development of robust biological nanotemplates with enhanced inorganic coating activities; novel coating strategies that allow for the deposition of a continuous inorganic layer onto a bio-nanotemplate even in the absence of a reducing agent; three-dimensional patterning methods for the assemble of nano-featured high aspect ratio surfaces and the demonstrated use of these surfaces in enhancing battery and energy storage applications. Combined results from this project have significantly advanced our understanding and ability to utilize the unique self-assembly properties of biologically based molecules to produce novel materials at the nanoscale level.

  4. Conductive Nanowires Templated by Molecular Brushes.

    PubMed

    Raguzin, Ivan; Stamm, Manfred; Ionov, Leonid

    2015-10-21

    In this paper, we report the fabrication of conductive nanowires using polymer bottle brushes as templates. In our approach, we synthesized poly(2-dimethylamino)ethyl methacrylate methyl iodide quaternary salt brushes by two-step atom transfer radical polymerization, loaded them with palladium salt, and reduced them in order to form metallic nanowires with average lengths and widths of 300 and 20 nm, respectively. The obtained nanowires were deposited between conductive gold pads and were connected to them by sputtering of additional pads to form an electric circuit. We connected the nanowires in an electric circuit and demonstrated that the conductivity of these nanowires is around 100 S·m(-1). PMID:26418290

  5. Metal-oxide-based energetic materials and synthesis thereof

    DOEpatents

    Tillotson, Thomas M. , Simpson; Randall L.; Hrubesh, Lawrence W.

    2006-01-17

    A method of preparing energetic metal-oxide-based energetic materials using sol-gel chemistry has been invented. The wet chemical sol-gel processing provides an improvement in both safety and performance. Essentially, a metal-oxide oxidizer skeletal structure is prepared from hydrolyzable metals (metal salts or metal alkoxides) with fuel added to the sol prior to gelation or synthesized within the porosity metal-oxide gel matrix. With metal salt precursors a proton scavenger is used to destabilize the sol and induce gelation. With metal alkoxide precursors standard well-known sol-gel hydrolysis and condensation reactions are used. Drying is done by standard sol-gel practices, either by a slow evaporation of the liquid residing within the pores to produce a high density solid nanocomposite, or by supercritical extraction to produce a lower density, high porous nanocomposite. Other ingredients may be added to this basic nanostructure to change physical and chemical properties, which include organic constituents for binders or gas generators during reactions, burn rate modifiers, or spectral emitters.

  6. Supply-Chain Optimization Template

    NASA Technical Reports Server (NTRS)

    Quiett, William F.; Sealing, Scott L.

    2009-01-01

    The Supply-Chain Optimization Template (SCOT) is an instructional guide for identifying, evaluating, and optimizing (including re-engineering) aerospace- oriented supply chains. The SCOT was derived from the Supply Chain Council s Supply-Chain Operations Reference (SCC SCOR) Model, which is more generic and more oriented toward achieving a competitive advantage in business.

  7. Viral-templated Palladium Nanocatalysts

    NASA Astrophysics Data System (ADS)

    Yang, Cuixian

    Despite recent progress on nanocatalysis, there exist several critical challenges in simple and readily controllable nanocatalyst synthesis including the unpredictable particle growth, deactivation of catalytic activity, cumbersome catalyst recovery and lack of in-situ reaction monitoring. In this dissertation, two novel approaches are presented for the fabrication of viral-templated palladium (Pd) nanocatalysts, and their catalytic activities for dichromate reduction reaction and Suzuki Coupling reaction were thoroughly studied. In the first approach, viral template based bottom-up assembly is employed for the Pd nanocatalyst synthesis in a chip-based format. Specifically, genetically displayed cysteine residues on each coat protein of Tobacco Mosaic Virus (TMV) templates provide precisely spaced thiol functionalities for readily controllable surface assembly and enhanced formation of catalytically active Pd nanoparticles. Catalysts with the chip-based format allow for simple separation and in-situ monitoring of the reaction extent. Thorough examination of synthesis-structure-activity relationship of Pd nanoparticles formed on surface-assembled viral templates shows that Pd nanoparticle size, catalyst loading density and catalytic activity of viral-templated Pd nanocatalysts can be readily controlled simply by tuning the synthesis conditions. The viral-templated Pd nanocatalysts with optimized synthesis conditions are shown to have higher catalytic activity per unit Pd mass than the commercial Pd/C catalysts. Furthermore, tunable and selective surface assembly of TMV biotemplates is exploited to control the loading density and location of Pd nanocatalysts on solid substrates via preferential electroless deposition. In addition, the catalytic activities of surface-assembled TMV-templated Pd nanocatalysts were also investigated for the ligand-free Suzuki Coupling reaction under mild reaction conditions. The chip-based format enables simple catalyst separation and

  8. Spreadsheet Templates for Chemical Equilibrium Calculations.

    ERIC Educational Resources Information Center

    Joshi, Bhairav D.

    1993-01-01

    Describes two general spreadsheet templates to carry out all types of one-equation chemical equilibrium calculations encountered by students in undergraduate chemistry courses. Algorithms, templates, macros, and representative examples are presented to illustrate the approach. (PR)

  9. Controlled synthesis of highly dispersed TiO2 nanoparticles using SBA-15 as hard template.

    PubMed

    Zhao, Li; Yu, Jiaguo

    2006-12-01

    Highly dispersed TiO2 nanoparticles were successfully synthesized by a wet impregnation method using SBA-15 as hard template for confining the growth of TiO2 nanocrystals, and then calcined at 550 degrees C in muffle furnace for 2 h. The as-synthesized samples were characterized with Fourier transform infrared spectra (FTIR), Raman spectroscopy, diffuse reflectance UV-visible spectroscopy (UV-vis), powder X-ray diffraction (XRD), small-angle X-ray diffraction (SAXRD), nitrogen adsorption, transmission electron microscopy (TEM) and photoluminescence spectra (PL). It was found that SBA-15 contained abundant silanol groups after removal of triblock copolymers by ethanol extraction and could easily adsorb a great number of titanium alkoxide via chemisorption. After subsequent hydrolysis of the anchored Ti complexes and calcination of the amorphous TiO2, anatase TiO2 nanocrystals with spherical shape and uniform particle diameter of about 6 nm were formed. A blue shift was observed in UV-vis absorption spectra due to the quantum size effect of TiO2 nanoparticles. Moreover, the as-prepared TiO2 nanoparticles showed a high PL intensity due to an increase in the recombination rate of photogenerated electrons and holes under UV light irradiation. PMID:16989852

  10. Assembly of a bacteriophage-based template for the organization of materials into nanoporous networks

    PubMed Central

    Courchesne, Noémie-Manuelle Dorval; Klug, Matthew T.; Chen, Po-Yen; Kooi, Steven E.; Yun, Dong Soo; Hong, Nina; Fang, Nicholas X.

    2014-01-01

    M13 bacteriophages are assembled via a covalent layer-by-layer process to form a highly nanoporous network capable of organizing nanoparticles and acting as a scaffold for templating metal-oxides. The morphological and optical properties of the film itself are presented as well as its ability to organize and disperse metal nanoparticles. PMID:24648015

  11. AN EXPRESSION TEMPLATE AWARE LAMBDA FUNCTION

    SciTech Connect

    S. A. SMITH; J. STRIEGNITZ

    2000-09-19

    The authors show how the paradigms of lambda functions and expression templates fit together in order to provide a means to increase the expressiveness of existing STL algorithms. They demonstrate how the expression templates approach could be extended in order to work with built-in types. To be portable, their solution is based on the Portable Expression Template Engine (PETE), which is a framework that enables the development of expression template aware classes.

  12. Inexpensive casing-supported drilling templates

    SciTech Connect

    Harrington, J.P.; Williams, L.M.

    1986-06-01

    Three types of inexpensive casing-supported templates have been designed and developed for use as spacer templates for tieback operations or for simple subsea completions. Two of the template concepts have been used in three areas of the southern North Sea. The design principles and running procedures are described, and the design of ancillary equipment used in the diverless installation of these templates is also illustrated.

  13. Metallic nanoshells on porphyrin-stabilized emulsions

    DOEpatents

    Wang, Haorong; Song, Yujiang; Shelnutt, John A; Medforth, Craig J

    2013-10-29

    Metal nanostructures formed by photocatalytic interfacial synthesis using a porphyrin-stabilized emulsion template and the method for making the nanostructures. Catalyst-seeded emulsion droplets are employed as templates for hollow-nanoshell growth. The hollow metal nanospheres may be formed with or without inclusions of other materials.

  14. Templated electrodeposition of silver nanowires in a nanoporous polycarbonate membrane from a nonaqueous ionic liquid electrolyte

    NASA Astrophysics Data System (ADS)

    Kazeminezhad, I.; Barnes, A. C.; Holbrey, J. D.; Seddon, K. R.; Schwarzacher, W.

    2007-03-01

    Template electrodeposition has been used to prepare a wide range of nanostructures but has generally been restricted to aqueous electrolytes. We report the deposition of silver nanowires in a commercial nuclear track-etched polycarbonate template from the nonaqueous ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) using silver electrochemically dissolved from the anode. Transmission electron microscopy (TEM) shows that the nanowires have a very high aspect ratio with an average diameter of 80 nm and length of 5 μm. Ionic liquid electrolytes should greatly extend the range of metals that can be electrodeposited as nanowires using templates.

  15. Template-assisted three-dimensional nanolithography via geometrically irreversible processing.

    PubMed

    Yu, Xindi; Zhang, Huigang; Oliverio, John K; Braun, Paul V

    2009-12-01

    An innovative and versatile nanofabrication technique based on template assisted three-dimensional (3D) nanolithography is presented that takes advantage of the irreversibility of conformal growth and conformal etching at locations with negative surface curvatures in 3D templates. Using colloidal crystals as templates, nanoring particles are generated with quantity much higher than conventional methods. Relying on the same principle, metallodielectric photonic crystals with discrete metal elements are fabricated that show strong absorption in the near-IR and transmission at longer wavelengths.

  16. Template-Assisted Direct Growth of 1 Td/in(2) Bit Patterned Media.

    PubMed

    Yang, En; Liu, Zuwei; Arora, Hitesh; Wu, Tsai-Wei; Ayanoor-Vitikkate, Vipin; Spoddig, Detlef; Bedau, Daniel; Grobis, Michael; Gurney, Bruce A; Albrecht, Thomas R; Terris, Bruce

    2016-07-13

    We present a method for growing bit patterned magnetic recording media using directed growth of sputtered granular perpendicular magnetic recording media. The grain nucleation is templated using an epitaxial seed layer, which contains Pt pillars separated by amorphous metal oxide. The scheme enables the creation of both templated data and servo regions suitable for high density hard disk drive operation. We illustrate the importance of using a process that is both topographically and chemically driven to achieve high quality media. PMID:27295317

  17. Template-Assisted Direct Growth of 1 Td/in(2) Bit Patterned Media.

    PubMed

    Yang, En; Liu, Zuwei; Arora, Hitesh; Wu, Tsai-Wei; Ayanoor-Vitikkate, Vipin; Spoddig, Detlef; Bedau, Daniel; Grobis, Michael; Gurney, Bruce A; Albrecht, Thomas R; Terris, Bruce

    2016-07-13

    We present a method for growing bit patterned magnetic recording media using directed growth of sputtered granular perpendicular magnetic recording media. The grain nucleation is templated using an epitaxial seed layer, which contains Pt pillars separated by amorphous metal oxide. The scheme enables the creation of both templated data and servo regions suitable for high density hard disk drive operation. We illustrate the importance of using a process that is both topographically and chemically driven to achieve high quality media.

  18. Electronic Structure of a CuII-Alkoxide Complex Modeling Intermediates in Copper-Catalyzed Alcohol Oxidations

    PubMed Central

    Hayes, Ellen C.; Porter, Thomas R.; Barrows, Charles J.; Kaminsky, Werner; Mayer, James M.; Stoll, Stefan

    2016-01-01

    In the copper-catalyzed oxidation of alcohols to aldehydes, a CuII-alkoxide (CuII-OR) intermediate is believed to modulate the αC-H bond strength of the deprotonated substrate to facilitate the oxidation. As a structural model for these intermediates, we characterized the electronic structure of the stable compound TptBuCuII(OCH2CF3) (TptBu = (hydro-tris (3-tert-butyl-pyrazolyl) borate) and investigated the influence of the trifluoroethoxide ligand on the electronic structure of the complex. The compound exhibits an electron paramagnetic resonance (EPR) spectrum with an unusually large gzz value of 2.44 and a small copper hyperfine coupling Azz of 40·10−4 cm−1 (120 MHz). Single-crystal electron nuclear double resonance (ENDOR) spectra show that the unpaired spin population is highly localized on the copper ion (≈ 68 %), with no more than 15 % on the ethoxide oxygen. Electronic absorption and magnetic circular dichroism (MCD) spectra show weak ligand-field transitions between 5000 and 12000 cm−1 and an intense ethoxide-to-copper charge transfer (LMCT) transition at 24000 cm−1, resulting in the red color of this complex. Resonance Raman (rR) spectroscopy reveals a Cu-O stretch mode at 592 cm−1. Quantum chemical calculations support the interpretation and assignment of the experimental data. Compared to known CuII-thiolate and CuII-alkylperoxo complexes from the literature, we found an increased σ interaction in the CuII-OR bond that results in the spectroscopic features. These insights lay the basis for further elucidating the mechanism of copper-catalyzed alcohol oxidations. PMID:26907976

  19. Electronic Structure of a Cu(II)-Alkoxide Complex Modeling Intermediates in Copper-Catalyzed Alcohol Oxidations.

    PubMed

    Hayes, Ellen C; Porter, Thomas R; Barrows, Charles J; Kaminsky, Werner; Mayer, James M; Stoll, Stefan

    2016-03-30

    In the copper-catalyzed oxidation of alcohols to aldehydes, a Cu(II)-alkoxide (Cu(II)-OR) intermediate is believed to modulate the αC-H bond strength of the deprotonated substrate to facilitate the oxidation. As a structural model for these intermediates, we characterized the electronic structure of the stable compound Tp(tBu)Cu(II)(OCH2CF3) (Tp(tBu) = hydro-tris(3-tert-butyl-pyrazolyl)borate) and investigated the influence of the trifluoroethoxide ligand on the electronic structure of the complex. The compound exhibits an electron paramagnetic resonance (EPR) spectrum with an unusually large gzz value of 2.44 and a small copper hyperfine coupling Azz of 40 × 10(-4) cm(-1) (120 MHz). Single-crystal electron nuclear double resonance (ENDOR) spectra show that the unpaired spin population is highly localized on the copper ion (≈68%), with no more than 15% on the ethoxide oxygen. Electronic absorption and magnetic circular dichroism (MCD) spectra show weak ligand-field transitions between 5000 and 12,000 cm(-1) and an intense ethoxide-to-copper charge transfer (LMCT) transition at 24,000 cm(-1), resulting in the red color of this complex. Resonance Raman (rR) spectroscopy reveals a Cu-O stretch mode at 592 cm(-1). Quantum chemical calculations support the interpretation and assignment of the experimental data. Compared to known Cu(II)-thiolate and Cu(II)-alkylperoxo complexes from the literature, we found an increased σ interaction in the Cu(II)-OR bond that results in the spectroscopic features. These insights lay the basis for further elucidating the mechanism of copper-catalyzed alcohol oxidations. PMID:26907976

  20. Characteristics of tetrahydrofuran-based electrolytes with magnesium alkoxide additives for rechargeable magnesium batteries

    NASA Astrophysics Data System (ADS)

    Kim, In-Tae; Yamabuki, Kazuhiro; Sumimoto, Michinori; Tsutsumi, Hiromori; Morita, Masayuki; Yoshimoto, Nobuko

    2016-08-01

    The electrochemical behavior of magnesium (Mg) metal was investigated in tetrahydrofuran (THF)-based solutions containing magnesium bromide (MgBr2) and/or magnesium ethoxide (Mg(OEt)2). THF solutions containing a single solute, MgBr2 or Mg(OEt)2, show no visible faradaic current based on Mg deposition and/or dissolution. However, the electrolyte system containing both solutes, MgBr2 + Mg(OEt)2/THF, gives a reversible current response of Mg deposition and dissolution. The ionic structure of the electrolyte system containing the binary solute was examined by infrared (IR) spectroscopy and density functional theory (DFT) calculations. It was confirmed that MgBr2 and Mg(OEt)2 are coordinated (solvated) with THF molecules to form an EtOsbnd Mgsbnd Br·4THF complex. The DFT calculations also suggest the possible formation of μ-complexes for the MgBr2/Mg(OEt)2 binary system in THF. The voltammetric responses at the Pt electrode indicate low overpotential and high coulombic efficiency for Mg deposition and dissolution in THF-based solutions containing suitable molar ratios of MgBr2 and Mg(OEt)2. The constant-current charge-discharge cycling of Mg in MgBr2 + Mg(OEt)2/THF electrolyte also shows low overpotential and good cyclability over 300 cycles.

  1. Fabrication of metal nanoshells

    NASA Technical Reports Server (NTRS)

    Kim, Jae-Woo (Inventor); Choi, Sang H. (Inventor); Lillehei, Peter T. (Inventor); Chu, Sang-Hyon (Inventor); Park, Yeonjoon (Inventor); King, Glen C. (Inventor); Elliott, Jr., James R. (Inventor)

    2012-01-01

    Metal nanoshells are fabricated by admixing an aqueous solution of metal ions with an aqueous solution of apoferritin protein molecules, followed by admixing an aqueous solution containing an excess of an oxidizing agent for the metal ions. The apoferritin molecules serve as bio-templates for the formation of metal nanoshells, which form on and are bonded to the inside walls of the hollow cores of the individual apoferritin molecules. Control of the number of metal atoms which enter the hollow core of each individual apoferritin molecule provides a hollow metal nonparticle, or nanoshell, instead of a solid spherical metal nanoparticle.

  2. Three-Dimensional Bicontinuous Graphene Monolith from Polymer Templates.

    PubMed

    Liu, Kewei; Chen, Yu-Ming; Policastro, Gina M; Becker, Matthew L; Zhu, Yu

    2015-06-23

    The two-dimensional single-layer and few-layered graphene exhibit many attractive properties such as large specific surface area and high charge carrier mobility. However, graphene sheets tend to stack together and form aggregates, which do not possess the desirable properties associated with graphene. Herein, we report a method to fabricate three-dimensional (3D), bicontinuous graphene monolith through a versatile hollow nickel (Ni) template derived from polymer blends. The poly(styrene)/poly(ethylene oxide) were used to fabricate a bicontinuous gyroid template using controlled phase separation. The Ni template was formed by electroless metal depositing on the polymer followed by removing the polymer phase. The resulting hollow Ni structure was highly porous (95.2%). Graphene was then synthesized from this hollow Ni template using chemical vapor deposition and the free-standing bicontinuous graphene monolith was obtained in high-throughput process. Finally, the bicontinuous graphene monolith was used directly as binder-free electrode in supercapacitor applications. The supercapacitor devices exhibited excellent stability.

  3. Mechanism of formation of supramolecular DNA-templated polymer nanowires.

    PubMed

    Watson, Scott M D; Galindo, Miguel A; Horrocks, Benjamin R; Houlton, Andrew

    2014-05-01

    Details of the mechanism of formation of supramolecular polymer nanowires by templating on DNA are revealed for the first time using AFM. Overall these data reveal that the smooth, regular, structures produced are rendered by highly dynamic supramolecular transformations occurring over the micrometre scale. In the initial stages of the process a low density of conducting polymer (CP) binds to the DNA as, essentially, spherical particles. Further reaction time produces DNA strands which are more densely packed with particles giving a beads-on-a-string appearance. The particles subsequently undergo dynamic reconfiguration so as to elongate along the template axis and merge to yield the highly regular, smooth morphology of the final nanowire. MD simulations illustrate the early stages of the process showing the binding of globular CP to duplex DNA, while the latter stages can be modeled effectively by a linear thermodynamic description based on the balance between the line energy, which accounts for adhesion of the material to the template, and its surface tension. This model accounts for the phenomena observed in the AFM studies: the relative success of DNA templating of polymers compared to metals; the slow approach to equilibrium; and the observed thinning and 'necking' phenomena as the structures transform from beads-on-a-string to smooth nanowire. PMID:24712548

  4. Ordered nanoparticle arrays formed on engineered chaperonin protein templates

    NASA Technical Reports Server (NTRS)

    McMillan, R. Andrew; Paavola, Chad D.; Howard, Jeanie; Chan, Suzanne L.; Zaluzec, Nestor J.; Trent, Jonathan D.

    2002-01-01

    Traditional methods for fabricating nanoscale arrays are usually based on lithographic techniques. Alternative new approaches rely on the use of nanoscale templates made of synthetic or biological materials. Some proteins, for example, have been used to form ordered two-dimensional arrays. Here, we fabricated nanoscale ordered arrays of metal and semiconductor quantum dots by binding preformed nanoparticles onto crystalline protein templates made from genetically engineered hollow double-ring structures called chaperonins. Using structural information as a guide, a thermostable recombinant chaperonin subunit was modified to assemble into chaperonins with either 3 nm or 9 nm apical pores surrounded by chemically reactive thiols. These engineered chaperonins were crystallized into two-dimensional templates up to 20 microm in diameter. The periodic solvent-exposed thiols within these crystalline templates were used to size-selectively bind and organize either gold (1.4, 5 or 10nm) or CdSe-ZnS semiconductor (4.5 nm) quantum dots into arrays. The order within the arrays was defined by the lattice of the underlying protein crystal. By combining the self-assembling properties of chaperonins with mutations guided by structural modelling, we demonstrate that quantum dots can be manipulated using modified chaperonins and organized into arrays for use in next-generation electronic and photonic devices.

  5. Ordered nanoparticle arrays formed on engineered chaperonin protein templates.

    SciTech Connect

    McMillan, R. A.; Paavola, C. D.; Howard, J.; Chan, S. L.; Zaluzec, N. J.; Trent, J. D.; Materials Science Division; NASA Ames Research Center; SETI Inst.

    2002-12-01

    Traditional methods for fabricating nanoscale arrays are usually based on lithographic techniques. Alternative new approaches rely on the use of nanoscale templates made of synthetic or biological materials. Some proteins, for example, have been used to form ordered two-dimensional arrays. Here, we fabricated nanoscale ordered arrays of metal and semiconductor quantum dots by binding preformed nanoparticles onto crystalline protein templates made from genetically engineered hollow double-ring structures called chaperonins. Using structural information as a guide, a thermostable recombinant chaperonin subunit was modified to assemble into chaperonins with either 3 nm or 9 nm apical pores surrounded by chemically reactive thiols. These engineered chaperonins were crystallized into two-dimensional templates up to 20 m in diameter. The periodic solvent-exposed thiols within these crystalline templates were used to size-selectively bind and organize either gold (1.4, 5 or 10nm) or CdSe-ZnS semiconductor (4.5 nm) quantum dots into arrays. The order within the arrays was defined by the lattice of the underlying protein crystal. By combining the self-assembling properties of chaperonins with mutations guided by structural modelling, we demonstrate that quantum dots can be manipulated using modified chaperonins and organized into arrays for use in next-generation electronic and photonic devices.

  6. Determination of Rhodium-Alkoxide Bond Strengths in Tp'Rh(PMe3)(OR)H.

    PubMed

    Yuwen, Jing; Jiao, Yunzhe; Brennessel, William W; Jones, William D

    2016-09-19

    The active fragment [Tp'Rh(PMe3)], generated from a thermal precursor Tp'Rh(PMe3)(CH3)H, underwent oxidative addition of water and alcohols to give O-H adducts of the type Tp'Rh(PMe3)(OR)H (R = H, Me, Et, (n)Pr, (n)Bu, CH2Ph, (i)Pr, c-pentyl, CH2CF3, CH2CH2OH) at ambient temperature. These activation products eliminate water or alcohols in benzene, which allows determination of the relative metal-oxygen bond energies by using previously established kinetics techniques. Analysis of the relationship between the relative M-O bond strengths and O-H bond strengths showed a linear correlation with RM-O/O-H of 0.97 (3) for aliphatic alcohols. The two extraordinary substrates (R = CH2CF3, CH2CH2OH) both have stronger M-O bonds than would be predicted from this trend, suggesting the stabilization of the M-O bond when an electron-withdrawing substituent is present as previously seen in M-C bond strengths. In addition, the O-H activation products of aliphatic alcohols are thermally unstable at 80 °C, as rearrangement to form Tp'Rh(PMe3)H2 from β-elimination is observed after 1 or 2 d. Benzyl alcohol and 2,2,2-trifluoroethanol activation products were stable. For benzyl alcohol, although the O-H activation product was kinetically favored, the C-H activation products of the benzene ring were thermodynamically preferred. PMID:27602591

  7. Metallic nanowire networks

    DOEpatents

    Song, Yujiang; Shelnutt, John A.

    2012-11-06

    A metallic nanowire network synthesized using chemical reduction of a metal ion source by a reducing agent in the presence of a soft template comprising a tubular inverse micellar network. The network of interconnected polycrystalline nanowires has a very high surface-area/volume ratio, which makes it highly suitable for use in catalytic applications.

  8. Testing sensory evidence against mnemonic templates.

    PubMed

    Myers, Nicholas E; Rohenkohl, Gustavo; Wyart, Valentin; Woolrich, Mark W; Nobre, Anna C; Stokes, Mark G

    2015-01-01

    Most perceptual decisions require comparisons between current input and an internal template. Classic studies propose that templates are encoded in sustained activity of sensory neurons. However, stimulus encoding is itself dynamic, tracing a complex trajectory through activity space. Which part of this trajectory is pre-activated to reflect the template? Here we recorded magneto- and electroencephalography during a visual target-detection task, and used pattern analyses to decode template, stimulus, and decision-variable representation. Our findings ran counter to the dominant model of sustained pre-activation. Instead, template information emerged transiently around stimulus onset and quickly subsided. Cross-generalization between stimulus and template coding, indicating a shared neural representation, occurred only briefly. Our results are compatible with the proposal that template representation relies on a matched filter, transforming input into task-appropriate output. This proposal was consistent with a signed difference response at the perceptual decision stage, which can be explained by a simple neural model.

  9. Distorted colloidal arrays as designed template

    NASA Astrophysics Data System (ADS)

    Yu, Ye; Zhou, Ziwei; Möhwald, Helmuth; Ai, Bin; Zhao, Zhiyuan; Ye, Shunsheng; Zhang, Gang

    2015-01-01

    In this paper, a novel type of colloidal template with broken symmetry was generated using commercial, inductively coupled plasma reactive ion etching (ICP-RIE). With proper but simple treatment, the traditional symmetric non-close-packed colloidal template evolves into an elliptical profile with high uniformity. This unique feature can add flexibility to colloidal lithography and/or other lithography techniques using colloidal particles as building blocks to fabricate nano-/micro-structures with broken symmetry. Beyond that the novel colloidal template we developed possesses on-site tunability, i.e. the transformability from a symmetric into an asymmetric template. Sandwich-type particles with eccentric features were fabricated utilizing this tunable template. This distinguishing feature will provide the possibility to fabricate structures with unique asymmetric features using one set of colloidal template, providing flexibility and broad tunability to enable nano-/micro-structure fabrication with colloidal templates.

  10. Oxide formation upon thermolysis of a Pb(II)/Zr(IV) alkoxide

    SciTech Connect

    Teff, D.J.; Huffman, J.C.; Caulton, K.G.

    1996-05-01

    While Pb({mu}-O{sup t}Bu){sub 3}Zr(O{sup t}Bu){sub 3} is stable for days in refluxing toluene, addition of stoichiometric [Pb(O{sup t}Bu){sub 2}]{sub 3} prior to reflux yields {sup t}BuOH, H{sub 2}C=CMe{sub 2}, and Pb{sub 3}ZrO(O{sup t}Bu){sub 8}, which was characterized by multinuclear NMR and X-ray diffraction. Highly pure [Pb(O{sup t}Bu){sub 2}]{sub 3} itself is unchanged in refluxing toluene, although it is slowly converted to Pb{sub 4}O(O{sup t}Bu){sub 6} by catalytic quantities of {sup t}BuOH, LiNme{sub 2}, or HN(SiMe{sub 3}){sub 2}, but not by Pb metal. Stoichiometric water converts [Pb(O{sup t}Bu){sub 2}]{sub 3} completely to Pb{sub 4}O(O{sup t}Bu){sub 6}, which reacts at 25{degree}C with Zr(O{sup t}Bu){sub 4} to give Pb{sub 3}ZrO(O{sup t}Bu){sub 8}. The mechanism of the formation of Pb{sub 3}ZrO(O{sup t}Bu){sub 8} is suggested to involve O/C heterolysis and C-H bond scission as the rate determining step during thermolysis. Convenient syntheses of Pb{sub 4}O(O{sup t}Bu){sub 6} and Pb{sub 6}O{sub 4}(O{sup t}Bu){sub 4} are described, and {sup 207}Pb and {sup 17}O NMR spectra of all species are described. Crystallographic data for Pb{sub 3}ZrO(O{sup t}Bu){sub 8} (at -174{degree}C) include a = 16.663(2) A, b = 12.608(1), c = 21.117(2), and Z = 4 in space group Pbc2{sub 1}. 27 refs., 2 figs., 2 tabs.

  11. FUZZY SUPERNOVA TEMPLATES. I. CLASSIFICATION

    SciTech Connect

    Rodney, Steven A.; Tonry, John L. E-mail: jt@ifa.hawaii.ed

    2009-12-20

    Modern supernova (SN) surveys are now uncovering stellar explosions at rates that far surpass what the world's spectroscopic resources can handle. In order to make full use of these SN data sets, it is necessary to use analysis methods that depend only on the survey photometry. This paper presents two methods for utilizing a set of SN light-curve templates to classify SN objects. In the first case, we present an updated version of the Bayesian Adaptive Template Matching program (BATM). To address some shortcomings of that strictly Bayesian approach, we introduce a method for Supernova Ontology with Fuzzy Templates (SOFT), which utilizes fuzzy set theory for the definition and combination of SN light-curve models. For well-sampled light curves with a modest signal-to-noise ratio (S/N >10), the SOFT method can correctly separate thermonuclear (Type Ia) SNe from core collapse SNe with >=98% accuracy. In addition, the SOFT method has the potential to classify SNe into sub-types, providing photometric identification of very rare or peculiar explosions. The accuracy and precision of the SOFT method are verified using Monte Carlo simulations as well as real SN light curves from the Sloan Digital Sky Survey and the SuperNova Legacy Survey. In a subsequent paper, the SOFT method is extended to address the problem of parameter estimation, providing estimates of redshift, distance, and host galaxy extinction without any spectroscopy.

  12. Titanium template for scaphoid reconstruction.

    PubMed

    Haefeli, M; Schaefer, D J; Schumacher, R; Müller-Gerbl, M; Honigmann, P

    2015-06-01

    Reconstruction of a non-united scaphoid with a humpback deformity involves resection of the non-union followed by bone grafting and fixation of the fragments. Intraoperative control of the reconstruction is difficult owing to the complex three-dimensional shape of the scaphoid and the other carpal bones overlying the scaphoid on lateral radiographs. We developed a titanium template that fits exactly to the surfaces of the proximal and distal scaphoid poles to define their position relative to each other after resection of the non-union. The templates were designed on three-dimensional computed tomography reconstructions and manufactured using selective laser melting technology. Ten conserved human wrists were used to simulate the reconstruction. The achieved precision measured as the deviation of the surface of the reconstructed scaphoid from its virtual counterpart was good in five cases (maximal difference 1.5 mm), moderate in one case (maximal difference 3 mm) and inadequate in four cases (difference more than 3 mm). The main problems were attributed to the template design and can be avoided by improved pre-operative planning, as shown in a clinical case. PMID:25167978

  13. Template synthesis of nanophase mesocarbon.

    PubMed

    Yang, Nancy Y; Jian, Kengqing; Külaots, Indrek; Crawford, Gregory P; Hurt, Robert H

    2003-10-01

    Templating techniques are used increasingly to create carbon materials with precisely engineered pore systems. This article presents a new templating technique that achieves simultaneous control of pore structure and molecular (crystal) structure in a single synthesis step. With the use of discotic liquid crystalline precursors, unique carbon structures can be engineered by selecting the size and geometry of the confining spaces and selecting the template material to induce edge-on or face-on orientation of the discotic precursor. Here mesophase pitch is infiltrated by capillary forces into a nanoporous glass followed by slow carbonization and NaOH etching. The resulting porous carbon material exhibits interconnected solid grains about 100 nm in size, a monodisperse pore size of 60 nm, 42% total porosity, and an abundance of edge-plane inner surfaces that reflect the favored edge-on anchoring of the mesophase precursor on glass. This new carbon form is potentially interesting for a number of important applications in which uniform large pores, active-site-rich surfaces, and easy access to interlayer spaces in nanometric grains are advantageous.

  14. Influence of the nature of titanium alkoxide and of the acid of hydrolysis in the preparation of titanium-pillared montmorillonites

    NASA Astrophysics Data System (ADS)

    Del Castillo, H. L.; Gil, A.; Grange, P.

    1997-07-01

    Titanium-pillared montmorillonites using Ti(OC2H5)4, Ti(O-nC3H7)4, Ti(O-iC3H7)4 and Ti(O-nC4H,)4 as sources of titanium, and HCl, HClO4, HNO3, H2SO4, CH3CO2H and H3PO4 as acids for hydrolysis, have been prepared. The preparation of titanium-pillared clays (Ti-PILCS) is mainly affected by the acid/alkoxide mole ratio. The nature of the alkoxide influences both the basal spacing and the specific surface area. The use of Ti(OC2H5)4 as a source of titanium yielded the best textural and thermal stability results. The differences observed in the titanium-pillared clays as a function of the acid used for the hydrolysis seem to be mainly related to the pH of the solution of intercalation.

  15. Alkoxide coordination of iron(III) protoporphyrin IX by antimalarial quinoline methanols: a key interaction observed in the solid-state and solution.

    PubMed

    Gildenhuys, Johandie; Sammy, Chandre J; Müller, Ronel; Streltsov, Victor A; le Roex, Tanya; Kuter, David; de Villiers, Katherine A

    2015-10-14

    The quinoline methanol antimalarial drug mefloquine is a structural analogue of the Cinchona alkaloids, quinine and quinidine. We have elucidated the single crystal X-ray diffraction structure of the complexes formed between racemic erythro mefloquine and ferriprotoporphyrin IX (Fe(iii)PPIX) and show that alkoxide coordination is a key interaction in the solid-state. Mass spectrometry confirms the existence of coordination complexes of quinine, quinidine and mefloquine to Fe(iii)PPIX in acetonitrile. The length of the iron(iii)-O bond in the quinine and quinidine complexes as determined by Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy unequivocally confirms that coordination of the quinoline methanol compounds to Fe(iii)PPIX occurs in non-aqueous aprotic solution via their benzylic alkoxide functional group. UV-visible spectrophotometric titrations of the low-spin bis-pyridyl-Fe(iii)PPIX complex with each of the quinoline methanol compounds results in the displacement of a single pyridine molecule and subsequent formation of a six-coordinate pyridine-Fe(iii)PPIX-drug complex. We propose that formation of the drug-Fe(iii)PPIX coordination complexes is favoured in a non-aqueous environment, such as that found in lipid bodies or membranes in the malaria parasite, and that their existence may contribute to the mechanism of haemozoin inhibition or other toxicity effects that lead ultimately to parasite death. In either case, coordination is a key interaction to be considered in the design of novel antimalarial drug candidates.

  16. Radial growth of plasmon coupled gold nanowires on colloidal templates.

    PubMed

    Farrokhtakin, Elmira; Rodríguez-Fernández, Denis; Mattoli, Virgilio; Solís, Diego M; Taboada, José M; Obelleiro, Fernando; Grzelczak, Marek; Liz-Marzán, Luis M

    2015-07-01

    The library of plasmonic nanosystems keeps expanding with novel structures with the potential to provide new solutions to old problems in science and technology. We report the synthesis of a novel plasmonic system based on the growth of gold nanowires radially branching from the surface of silica particles. The nanowires length could be controlled by tuning the molar ratio between metal salt and surface-grafted seeds. Electron microscopy characterization revealed that the obtained one-dimensional nanoparticles are polycrystalline but uniformly distributed on the spherical template. The length of the nanowires in turn determines the optical response of the metallodielectric particles, so that longer wires display red-shifted longitudinal plasmon bands. Accurate theoretical modeling of these complex objects revealed that the densely organized nanowires display intrinsically coupled plasmon modes that can be selectively decoupled upon detachment of the nanowires from the surface of the colloidal silica template. PMID:25554084

  17. Radial growth of plasmon coupled gold nanowires on colloidal templates.

    PubMed

    Farrokhtakin, Elmira; Rodríguez-Fernández, Denis; Mattoli, Virgilio; Solís, Diego M; Taboada, José M; Obelleiro, Fernando; Grzelczak, Marek; Liz-Marzán, Luis M

    2015-07-01

    The library of plasmonic nanosystems keeps expanding with novel structures with the potential to provide new solutions to old problems in science and technology. We report the synthesis of a novel plasmonic system based on the growth of gold nanowires radially branching from the surface of silica particles. The nanowires length could be controlled by tuning the molar ratio between metal salt and surface-grafted seeds. Electron microscopy characterization revealed that the obtained one-dimensional nanoparticles are polycrystalline but uniformly distributed on the spherical template. The length of the nanowires in turn determines the optical response of the metallodielectric particles, so that longer wires display red-shifted longitudinal plasmon bands. Accurate theoretical modeling of these complex objects revealed that the densely organized nanowires display intrinsically coupled plasmon modes that can be selectively decoupled upon detachment of the nanowires from the surface of the colloidal silica template.

  18. Amine templated zinc phosphates phases for membrane separations

    SciTech Connect

    Nenoff, T.M.; Chavez, A.V.; Thoma, S.G.; Provencio, P.; Harrison, W.T.A.; Phillips, M.L.F.

    1998-08-01

    This research is focused on developing inorganic molecular sieve membranes for light gas separations such as hydrogen recovery and natural gas purification, and organic molecular separations, such as chiral enantiomers. The authors focus on zinc phosphates because of the ease in crystallization of new phases and the wide range of pore sizes and shapes obtained. With hybrid systems of zinc phosphate crystalline phases templated by amine molecules, the authors are interested in better understanding the association of the template molecules to the inorganic phase, and how the organic transfers its size, shape, and (in some cases) chirality to the bulk. Furthermore, the new porous phases can also be synthesized as thin films on metal oxide substrates. These films allow one to make membranes from organic/inorganic hybrid systems, suitable for diffusion experiments. Characterization techniques for both the bulk phases and the thin films include powder X-ray diffraction, TGA, Scanning Electron Micrograph (SEM) and Electron Dispersive Spectrometry (EDS).

  19. Stereolithographic Surgical Template: A Review

    PubMed Central

    Dandekeri, Shilpa Sudesh; Sowmya, M.K.; Bhandary, Shruthi

    2013-01-01

    Implant placement has become a routine modality of dental care.Improvements in surgical reconstructive methods as well as increased prosthetic demands,require a highly accurate diagnosis, planning and placement. Recently,computer-aided design and manufacturing have made it possible to use data from computerised tomography to not only plan implant rehabilitation,but also transfer this information to the surgery.A review on one of this technique called Stereolithography is presented in this article.It permits graphic and complex 3D implant placement and fabrication of stereolithographic surgical templates. Also offers many significant benefits over traditional procedures. PMID:24179955

  20. Learning templates for artistic portrait lighting analysis.

    PubMed

    Chen, Xiaowu; Jin, Xin; Wu, Hongyu; Zhao, Qinping

    2015-02-01

    Lighting is a key factor in creating impressive artistic portraits. In this paper, we propose to analyze portrait lighting by learning templates of lighting styles. Inspired by the experience of artists, we first define several novel features that describe the local contrasts in various face regions. The most informative features are then selected with a stepwise feature pursuit algorithm to derive the templates of various lighting styles. After that, the matching scores that measure the similarity between a testing portrait and those templates are calculated for lighting style classification. Furthermore, we train a regression model by the subjective scores and the feature responses of a template to predict the score of a portrait lighting quality. Based on the templates, a novel face illumination descriptor is defined to measure the difference between two portrait lightings. Experimental results show that the learned templates can well describe the lighting styles, whereas the proposed approach can assess the lighting quality of artistic portraits as human being does.

  1. An on-line template improvement algorithm

    NASA Astrophysics Data System (ADS)

    Yin, Yilong; Zhao, Bo; Yang, Xiukun

    2005-03-01

    In automatic fingerprint identification system, incomplete or rigid template may lead to false rejection and false matching. So, how to improve quality of the template, which is called template improvement, is important to automatic fingerprint identify system. In this paper, we propose a template improve algorithm. Based on the case-based method of machine learning and probability theory, we improve the template by deleting pseudo minutia, restoring lost genuine minutia and updating the information of minutia such as positions and directions. And special fingerprint image database is built for this work. Experimental results on this database indicate that our method is effective and quality of fingerprint template is improved evidently. Accordingly, performance of fingerprint matching is also improved stably along with the increase of using time.

  2. Cryogenic Gellant and Fuel Formulation for Metallized Gelled Propellants: Hydrocarbons and Hydrogen with Aluminum

    NASA Technical Reports Server (NTRS)

    Wong, Wing; Starkovich, John; Adams, Scott; Palaszewski, Bryan; Davison, William; Burt, William; Thridandam, Hareesh; Hu-Peng, Hsiao; Santy, Myrrl J.

    1994-01-01

    An experimental program to determine the viability of nanoparticulate gellant materials for gelled hydrocarbons and gelled liquid hydrogen was conducted. The gellants included alkoxides (BTMSE and BTMSH) and silica-based materials. Hexane, ethane, propane and hydrogen were gelled with the newly-formulated materials and their rheological properties were determined: shear stress versus shear rate and their attendant viscosities. Metallized hexane with aluminum particles was also rheologically characterized. The propellant and gellant formulations were selected for the very high surface area and relatively-high energy content of the gellants. These new gellants can therefore improve rocket engine specific impulse over that obtained with traditional cryogenic-fuel gellant materials silicon dioxide, frozen methane, or frozen ethane particles. Significant reductions in the total mass of the gellant were enabled in the fuels. In gelled liquid hydrogen, the total mass of gellant was reduced from 10-40 wt percent of frozen hydrocarbon particles to less that 8 wt percent with the alkoxide.

  3. Influence of template fill in graphoepitaxy DSA

    NASA Astrophysics Data System (ADS)

    Doise, Jan; Bekaert, Joost; Chan, Boon Teik; Hong, SungEun; Lin, Guanyang; Gronheid, Roel

    2016-03-01

    Directed self-assembly (DSA) of block copolymers (BCP) is considered a promising patterning approach for the 7 nm node and beyond. Specifically, a grapho-epitaxy process using a cylindrical phase BCP may offer an efficient solution for patterning randomly distributed contact holes with sub-resolution pitches, such as found in via and cut mask levels. In any grapho-epitaxy process, the pattern density impacts the template fill (local BCP thickness inside the template) and may cause defects due to respectively over- or underfilling of the template. In order to tackle this issue thoroughly, the parameters that determine template fill and the influence of template fill on the resulting pattern should be investigated. In this work, using three process flow variations (with different template surface energy), template fill is experimentally characterized as a function of pattern density and film thickness. The impact of these parameters on template fill is highly dependent on the process flow, and thus pre-pattern surface energy. Template fill has a considerable effect on the pattern transfer of the DSA contact holes into the underlying layer. Higher fill levels give rise to smaller contact holes and worse critical dimension uniformity. These results are important towards DSA-aware design and show that fill is a crucial parameter in grapho-epitaxy DSA.

  4. Method of installing sub-sea templates

    SciTech Connect

    Hampton, J.E.

    1984-03-06

    A subsea template is installed by a method which includes the steps of securing the template in a position beneath the deck of a semi-submersible drilling vessel, moving the semi-submersible drilling vessel to an appropriate offshore site and subsequently lowering the template from the semi-submersible to the sea bed. In addition, at least three anchorage templates may be loaded onto one or both of the pontoons of the semi-submersible drilling vessel at its original position and are subsequently lowered from the pontoons to their respective locations on the sea bed after the semi-submersible has moved to the offshore site.

  5. Method for producing metal oxide aerogels

    DOEpatents

    Tillotson, T.M.; Poco, J.F.; Hrubesh, L.W.; Thomas, I.M.

    1995-04-25

    A two-step hydrolysis-condensation method was developed to form metal oxide aerogels of any density, including densities of less than 0.003g/cm{sup 3} and greater than 0.27g/cm{sup 3}. High purity metal alkoxide is reacted with water, alcohol solvent, and an additive to form a partially condensed metal intermediate. All solvent and reaction-generated alcohol is removed, and the intermediate is diluted with a nonalcoholic solvent. The intermediate can be stored for future use to make aerogels of any density. The aerogels are formed by reacting the intermediate with water, nonalcoholic solvent, and a catalyst, and extracting the nonalcoholic solvent directly. The resulting monolithic aerogels are hydrophobic and stable under atmospheric conditions, and exhibit good optical transparency, high clarity, and homogeneity. The aerogels have high thermal insulation capacity, high porosity, mechanical strength and stability, and require shorter gelation times than aerogels formed by conventional methods. 8 figs.

  6. Method for producing metal oxide aerogels

    DOEpatents

    Tillotson, Thomas M.; Poco, John F.; Hrubesh, Lawrence W.; Thomas, Ian M.

    1995-01-01

    A two-step hydrolysis-condensation method was developed to form metal oxide aerogels of any density, including densities of less than 0.003g/cm.sup.3 and greater than 0.27g/cm.sup.3. High purity metal alkoxide is reacted with water, alcohol solvent, and an additive to form a partially condensed metal intermediate. All solvent and reaction-generated alcohol is removed, and the intermediate is diluted with a nonalcoholic solvent. The intermediate can be stored for future use to make aerogels of any density. The aerogels are formed by reacting the intermediate with water, nonalcoholic solvent, and a catalyst, and extracting the nonalcoholic solvent directly. The resulting monolithic aerogels are hydrophobic and stable under atmospheric conditions, and exhibit good optical transparency, high clarity, and homogeneity. The aerogels have high thermal insulation capacity, high porosity, mechanical strength and stability, and require shorter gelation times than aerogels formed by conventional methods.

  7. Colloidal assembly by ice templating.

    PubMed

    Kumaraswamy, Guruswamy; Biswas, Bipul; Choudhury, Chandan Kumar

    2016-01-01

    We investigate ice templating of aqueous dispersions of polymer coated colloids and crosslinkers, at particle concentrations far below that required to form percolated monoliths. Freezing the aqueous dispersions forces the particles into close proximity to form clusters, that are held together as the polymer chains coating the particles are crosslinked. We observe that, with an increase in the particle concentration from about 10(6) to 10(8) particles per ml, there is a transition from isolated single particles to increasingly larger clusters. In this concentration range, most of the colloidal clusters formed are linear or sheet like particle aggregates. Remarkably, the cluster size distribution for clusters smaller than about 30 particles, as well as the size distribution of linear clusters, is only weakly dependent on the dispersion concentration in the range that we investigate. We demonstrate that the main features of cluster formation are captured by kinetic simulations that do not consider hydrodynamics or instabilities at the growing ice front due to particle concentration gradients. Thus, clustering of colloidal particles by ice templating dilute dispersions appears to be governed only by particle exclusion by the growing ice crystals that leads to their accumulation at ice crystal boundaries.

  8. Glycothermal synthesis of metal oxides

    NASA Astrophysics Data System (ADS)

    Inoue, Masashi

    2004-04-01

    The author has been exploring the synthesis of inorganic materials in organic solvents at temperatures (200-300 °C) higher than their boiling points (solvothermal reaction), and has developed various reaction methods for the synthesis of ultrafine particles of metal oxides. In this paper, the reactions of aluminium compounds (aluminium hydroxide (Al(OH)3; gibbsite), aluminium alkoxides, and aluminium salts) in various organic solvents (alcohols, glycols, aminoalcohols, and inert organic solvents) are first reviewed, and reaction mechanisms and effects of the starting materials and solvents on the products are discussed. Then, the specificity of the use of glycols, especially 1,4-butanediol (glycothermal reaction), is clarified, and glycothermal synthesis of crystalline mixed oxides such as yttrium aluminium garnet is described. Finally, the use of the solvothermally prepared products as the catalyst materials is described.

  9. Design of block copolymer templated solid state batteries

    NASA Astrophysics Data System (ADS)

    Bullock, Steven Edward

    The advent of portable electronics has placed a great demand on the power requirements of battery systems. High power batteries for small devices, such as cell phones, laptop computers, and personal data assistants (PDA's) have focused primarily on lithium ion batteries. With the introduction of large flexible panel displays, the need for a flexible battery system is apparent. Ring Opening Metathesis Polymerization (ROMP) is a facile method for synthesizing block copolymers with polar functional groups. These functional groups allow the formation of metal oxide clusters via a template of the microphase separated block copolymer domains. In this thesis, the synthesis of a flexible polymer battery system is described. Diblock copolymers of an ionically conductive unsaturated polyethylene oxide block with a carboxylic acid functionalized block were synthesized and characterized with NMR, IR and Gel Permeation Chromatography (GPC). Characterization of polymer templated LiMn2O 4 clusters and nanocomposites synthesized for the study have a distributed cluster morphology within the polymer matrix. The nanocomposites were analyzed with transmission electron microscopy to determine the morphology of the nanocomposites. Battery performance was characterized with cyclic voltammetry and galvanostatic charge/discharge cycling for power capacity. The ionic conductivity was measured with impedance spectroscopy. The novel room temperature templating strategy used for the synthesis of these ionically conductive nanocomposites requires no thermal cycling steps. This makes it attractive for processing of sheet structures to power flexible displays.

  10. Visual Templates in Pattern Generalization Activity

    ERIC Educational Resources Information Center

    Rivera, F. D.

    2010-01-01

    In this research article, I present evidence of the existence of visual templates in pattern generalization activity. Such templates initially emerged from a 3-week design-driven classroom teaching experiment on pattern generalization involving linear figural patterns and were assessed for existence in a clinical interview that was conducted four…

  11. Indexing Images: Testing an Image Description Template.

    ERIC Educational Resources Information Center

    Jorgensen, Corinne

    1996-01-01

    A template for pictorial image description to be used by novice image searchers in recording their descriptions of images was tested; image attribute classes derived in previous research were used to model the template. Results indicated that users may need training and/or more guidance to correctly assign descriptors to higher-level classes.…

  12. Air Sampling System Evaluation Template

    2000-05-09

    The ASSET1.0 software provides a template with which a user can evaluate an Air Sampling System against the latest version of ANSI N13.1 "Sampling and Monitoring Releases of Airborne Radioactive Substances from the Stacks and Ducts of Nuclear Facilities". The software uses the ANSI N13.1 PIC levels to establish basic design criteria for the existing or proposed sampling system. The software looks at such criteria as PIC level, type of radionuclide emissions, physical state ofmore » the radionuclide, nozzle entrance effects, particulate transmission effects, system and component accuracy and precision evaluations, and basic system operations to provide a detailed look at the subsystems of a monitoring and sampling system/program. A GAP evaluation can then be completed which leads to identification of design and operational flaws in the proposed systems. Corrective measures can then be limited to the GAPs.« less

  13. Solvable model for template coexistence in protocells

    NASA Astrophysics Data System (ADS)

    Fontanari, J. F.; Serva, M.

    2013-02-01

    Compartmentalization of self-replicating molecules (templates) in protocells is a necessary step towards the evolution of modern cells. However, coexistence between distinct template types inside a protocell can be achieved only if there is a selective pressure favoring protocells with a mixed template composition. Here we study analytically a group selection model for the coexistence between two template types using the diffusion approximation of population genetics. The model combines competition at the template and protocell levels as well as genetic drift inside protocells. At the steady state, we find a continuous phase transition separating the coexistence and segregation regimes, with the order parameter vanishing linearly with the distance to the critical point. In addition, we derive explicit analytical expressions for the critical steady-state probability density of protocell compositions.

  14. Nanoimprint lithography using disposable biomass template

    NASA Astrophysics Data System (ADS)

    Hanabata, Makoto; Takei, Satoshi; Sugahara, Kigen; Nakajima, Shinya; Sugino, Naoto; Kameda, Takao; Fukushima, Jiro; Matsumoto, Yoko; Sekiguchi, Atsushi

    2016-04-01

    A novel nanoimprint lithography process using disposable biomass template having gas permeability was investigated. It was found that a disposable biomass template derived from cellulose materials shows an excellent gas permeability and decreases transcriptional defects in conventional templates such as quartz, PMDS, DLC that have no gas permeability. We believe that outgasses from imprinted materials are easily removed through the template. The approach to use a cellulose for template material is suitable as the next generation of clean separation technology. It is expected to be one of the defect-less thermal nanoimprint lithographic technologies. It is also expected that volatile materials and solvent including materials become available that often create defects and peelings in conventional temples that have no gas permeability.

  15. Fluorinated Alkoxide-Based Magnesium-Ion Battery Electrolytes that Demonstrate Li-Ion-Battery-Like High Anodic Stability and Solution Conductivity.

    PubMed

    Crowe, Adam J; Stringham, Kyle K; Bartlett, Bart M

    2016-09-01

    Based on DFT predictions, a series of highly soluble fluorinated alkoxide-based electrolytes were prepared, examined electrochemically, and reversibly cycled. The alcohols react with ethylmagnesium chloride to generate a fluoroalkoxy-magnesium chloride intermediate, which subsequently reacts with aluminum chloride to generate the electrolyte. Solutions starting from a 1,1,1,3,3,3-hexafluoro-2-methylpropan-2-ol precursor exhibit high anodic stability, 3.2 V vs Mg(2+/0), and a record 3.5 mS/cm solution conductivity. Excellent galvanostatic cycling and capacity retention (94%) is observed with more than 300 h of cycle time while employing the standard Chevrel phase-Mo6S8 cathode material.

  16. The preparation of concentric-tubular composite microstructures and nanorod sols using template synthesis

    NASA Astrophysics Data System (ADS)

    Cepak, Veronica Marie

    1998-12-01

    Membrane-based template synthesis has been employed in the fabrication of concentric-tubular composite microstructures and nanorod organosols of two materials, metals and semiconductors. This type of template synthesis is unique because the cylindrical pores of filtration membranes were used as templates to prepare these materials. Insulating polymer nanofibrils and microtubules were prepared by template-assisted deposition. This method entailed filtering a polymer solution through a filtration membrane. Insulating microtubules that were obtained were further used to prepare concentric-tubular composite microstructure arrays consisting of an outer tubule of polystyrene surrounding an inner fibril of the conductive polymer, polypyrrole. The preparation and characterization of insulating polymer structures along with this microcomposite array was discussed. In addition, template synthesis has also been used to prepare a variety of other types of concentric-tubular microcomposite structures. Examples prepared consisted of Au/poly(phenylene oxide)/polypyrrole, Au/TiO2, and Au/ZnO to demonstrate the versatility of this method. These examples used the following chemistries: the electroless deposition of Au, electrochemical deposition of conductive and insulating polymers, electrodeposition of semiconductors, and sol-gel methods. Membrane-based template synthesis has also been used to prepare metal and semiconductor nanorod sols in organic solvents. Nanorods were prepared in the polycarbonate membrane's pores by electrochemical deposition of metals or semiconductors. The nanorod organosols were then prepared by immersing a nanorod/membrane composite into either CHCl3 or hexafluoroisopropanol. These organic solvents dissolved the template membrane and simultaneously dispersed the nanorods to form a sol. Ag, Au, CdS, and ZnO nanorod sols were prepared in this fashion. The metal nanorod sols were investigated by visible absorption spectroscopy. The position of the plasmon

  17. Attributes and templates from active measurements with {sup 252}Cf

    SciTech Connect

    Mihalczo, J.T.; Mattingly, J.K.

    2000-02-01

    Active neutron interrogation is useful for the detection of shielded HEU and could also be used for Pu. In an active technique, fissile material is stimulated by an external neutron source to produce fission with the emanation of neutrons and gamma rays. The time distribution of particles leaving the fissile material is measured with respect to the source emission in a variety of ways. A variety of accelerator and radioactive sources can be used. Active interrogation of nuclear weapons/components can be used in two ways: template matching or attribute estimation. Template matching compares radiation signatures with known reference signatures and for treaty applications has the problem of authentication of the reference signatures along with storage and retrieval of templates. Attribute estimation determines, for example, the fissile mass from various features of the radiation signatures and does not require storage of radiation signatures but does require calibration, which can be repeated as necessary. A nuclear materials identification system (NMIS) has been in use at the Oak Ridge Y-12 Plant for verification of weapons components being received and in storage by template matching and has been used with calibrations for attribute (fissile mass) estimation for HEU metal. NMIS employs a {sup 252}Cf source of low intensity (< 2 x 10{sup 6} n/sec) such that the dose at 1 m is approximately twice that on a commercial airline at altitude. The use of such a source presents no significant safety concerns either for personnel or nuclear explosive safety, and has been approved for use at the Pantex Plant on fully assembled weapons systems.

  18. Synthesis of metallic nanoshells on porphyrin-stabilized emulsions

    DOEpatents

    Wang, Haorong; Song, Yujiang; Shelnutt, John A.; Medforth, Craig J.

    2011-12-13

    Metal nanostructures formed by photocatalytic interfacial synthesis using a porphyrin-stabilized emulsion template and the method for making the nanostructures. Catalyst-seeded emulsion droplets are employed as templates for hollow-nanoshell growth. The hollow metal nanospheres may be formed with or without inclusions of other materials.

  19. First Synthesis of Continuous Mesoporous Copper Films with Uniformly Sized Pores by Electrochemical Soft Templating.

    PubMed

    Li, Cuiling; Jiang, Bo; Wang, Zhongli; Li, Yunqi; Hossain, Md Shahriar A; Kim, Jung Ho; Takei, Toshiaki; Henzie, Joel; Dag, Ömer; Bando, Yoshio; Yamauchi, Yusuke

    2016-10-01

    Although mesoporous metals have been synthesized by electrochemical methods, the possible compositions have been limited to noble metals (e.g., palladium, platinum, gold) and their alloys. Herein we describe the first fabrication of continuously mesoporous Cu films using polymeric micelles as soft templates to control the growth of Cu under sophisticated electrochemical conditions. Uniformly sized mesopores are evenly distributed over the entire film, and the pore walls are composed of highly crystalized Cu. PMID:27554196

  20. Testing sensory evidence against mnemonic templates

    PubMed Central

    Myers, Nicholas E; Rohenkohl, Gustavo; Wyart, Valentin; Woolrich, Mark W; Nobre, Anna C; Stokes, Mark G

    2015-01-01

    Most perceptual decisions require comparisons between current input and an internal template. Classic studies propose that templates are encoded in sustained activity of sensory neurons. However, stimulus encoding is itself dynamic, tracing a complex trajectory through activity space. Which part of this trajectory is pre-activated to reflect the template? Here we recorded magneto- and electroencephalography during a visual target-detection task, and used pattern analyses to decode template, stimulus, and decision-variable representation. Our findings ran counter to the dominant model of sustained pre-activation. Instead, template information emerged transiently around stimulus onset and quickly subsided. Cross-generalization between stimulus and template coding, indicating a shared neural representation, occurred only briefly. Our results are compatible with the proposal that template representation relies on a matched filter, transforming input into task-appropriate output. This proposal was consistent with a signed difference response at the perceptual decision stage, which can be explained by a simple neural model. DOI: http://dx.doi.org/10.7554/eLife.09000.001 PMID:26653854

  1. Template optimization and transfer in perceptual learning.

    PubMed

    Kurki, Ilmari; Hyvärinen, Aapo; Saarinen, Jussi

    2016-08-01

    We studied how learning changes the processing of a low-level Gabor stimulus, using a classification-image method (psychophysical reverse correlation) and a task where observers discriminated between slight differences in the phase (relative alignment) of a target Gabor in visual noise. The method estimates the internal "template" that describes how the visual system weights the input information for decisions. One popular idea has been that learning makes the template more like an ideal Bayesian weighting; however, the evidence has been indirect. We used a new regression technique to directly estimate the template weight change and to test whether the direction of reweighting is significantly different from an optimal learning strategy. The subjects trained the task for six daily sessions, and we tested the transfer of training to a target in an orthogonal orientation. Strong learning and partial transfer were observed. We tested whether task precision (difficulty) had an effect on template change and transfer: Observers trained in either a high-precision (small, 60° phase difference) or a low-precision task (180°). Task precision did not have an effect on the amount of template change or transfer, suggesting that task precision per se does not determine whether learning generalizes. Classification images show that training made observers use more task-relevant features and unlearn some irrelevant features. The transfer templates resembled partially optimized versions of templates in training sessions. The template change direction resembles ideal learning significantly but not completely. The amount of template change was highly correlated with the amount of learning. PMID:27559720

  2. Templated Growth of Magnetic Recording Media

    NASA Astrophysics Data System (ADS)

    Sundar, Vignesh

    Current and potential next-generation magnetic recording technologies are based on the writing and reading of bits on a magnetic thin film with a granular microstructure, with grains of the magnetic material surrounded by an amorphous segregant. In order to realize the highest achievable data storage capabilities, there is a need for better control of the magnetic media microstructure, particularly in terms of minimizing grain size and grain boundary thickness distributions. In this work, a guided magnetic media growth is attempted by creating a pre-fabricated template with a specific material and morphology. The template is designed in such a way that, when magnetic media consisting of the magnetic alloy and segregant are sputtered, the sites on the template result in a controlled two-phase growth of magnetic media. The template is fabricated using self-assembling block copolymers, which can be used to fabricate nanostructures with a regular hexagonal lattice of spheres of one block in the other's matrix. These are then used as etch-masks to fabricate the template. In this thesis, we describe the approach used to fabricate these templates and demonstrate the two-phase growth of magnetic recording media. In such an approach, the magnetic grain size is defined by the uniform pitch of the block copolymer pattern, resulting in a uniform microstructure with much better grain size distribution than can be obtained with conventional un-templated media growth. The templated growth technique is also a suitable additive technique for the fabrication of Bit Patterned Media, another potential next-generation technology wherein the magnetic bits are isolated patterned islands. Combining nanoimprint lithography with templated growth, we can generate a long range spatially ordered array of magnetic islands with no etching of the magnetic material.

  3. Self-assembly of hybrid structures on nano templates

    NASA Astrophysics Data System (ADS)

    Wang, Ruomiao

    This dissertation describes the investigation on the synthesis of hybrid structures on nano-templates. Fabrication of molecular nano-patterns of organic amphiphiles (e.g. fatty acids) by self-assembly has been discussed here, and their application as templates for two-dimensional in situ synthesis of metal soap molecular pattern has been demonstrated. The synthesis of nanoparticle---nanorod hybrid structure represents another effort to achieve hybrid materials. Therefore, methods to create complex inorganic---organic nano---hybrid are provided by this work. AFM disclosed the pattern structures of the self-assembled monolayers as designed nanoscaled patterns. It is observed two pattern periodicities reflecting the head-to-head and head-to-tail molecular assembly tendencies of the fatty acids and their dependence on the molecular structure and chain length, which exhibits a linear increase in the periodicity with an increasing molecular chain length. The investigation on molecular patterns of self-assembled monolayers of metal arachidates on graphite by AFM and FTIR is described. Metal arachidate self-assemblies show similar stripe pattern and periodicities as those of arachidic acid. The monolayer structure is mainly dictated by graphite, while the type of metal ions mainly affects the domain size, shape and regularity. The results of AFM and FTIR are correlated to the Irving-Williams Series, which predicts bond strength of the metal ions to ligands. The spin coated films from binary solutions of nanoparticles and fatty acids with different chain lengths (Even number of carbon, C18--C26), have been used to study the effect of nanoparticles on self-assemble pattern of fatty acids. C18--C22 acids formed uniform nanorods attached and induced by nanoparticles, while the self-assembled stripe patterns of C24 and C26 were unaffected by the presence of nanoparticles. The nanoparticles were aligned on C26 monolayer. The seeded nucleation mechanism has been studied by AFM

  4. Templated Native Silk Smectic Gels

    NASA Technical Reports Server (NTRS)

    Jin, Hyoung-Joon (Inventor); Park, Jae-Hyung (Inventor); Valluzzi, Regina (Inventor)

    2016-01-01

    One aspect of the present invention relates to a method of preparing a fibrous protein smectic hydrogel by way of a solvent templating process, comprising the steps of pouring an aqueous fibrous protein solution into a container comprising a solvent that is not miscible with water; sealing the container and allowing it to age at about room temperature; and collecting the resulting fibrous protein smectic hydrogel and allowing it to dry. Another aspect of the present invention relates to a method of obtaining predominantly one enantiomer from a racemic mixture, comprising the steps of pouring an aqueous fibrous protein solution into a container comprising a solvent that is not miscible with water; sealing the container and allowing it to age at about room temperature; allowing the enantiomers of racemic mixture to diffuse selectively into the smectic hydrogel in solution; removing the smectic hydrogel from the solution; rinsing predominantly one enantiomer from the surface of the smectic hydrogel; and extracting predominantly one enantiomer from the interior of the smectic hydrogel. The present invention also relates to a smectic hydrogel prepared according to an aforementioned method.

  5. Templated native silk smectic gels

    NASA Technical Reports Server (NTRS)

    Jin, Hyoung-Joon (Inventor); Park, Jae-Hyung (Inventor); Valluzzi, Regina (Inventor)

    2009-01-01

    One aspect of the present invention relates to a method of preparing a fibrous protein smectic hydrogel by way of a solvent templating process, comprising the steps of pouring an aqueous fibrous protein solution into a container comprising a solvent that is not miscible with water; sealing the container and allowing it to age at about room temperature; and collecting the resulting fibrous protein smectic hydrogel and allowing it to dry. Another aspect of the present invention relates to a method of obtaining predominantly one enantiomer from a racemic mixture, comprising the steps of pouring an aqueous fibrous protein solution into a container comprising a solvent that is not miscible with water; sealing the container and allowing it to age at about room temperature; allowing the enantiomers of racemic mixture to diffuse selectively into the smectic hydrogel in solution; removing the smectic hydrogel from the solution; rinsing predominantly one enantiomer from the surface of the smectic hydrogel; and extracting predominantly one enantiomer from the interior of the smectic hydrogel. The present invention also relates to a smectic hydrogel prepared according to an aforementioned method.

  6. Templated Native Silk Smectic Gels

    NASA Technical Reports Server (NTRS)

    Jin, Hyoung-Joon (Inventor); Park, Jae-Hyung (Inventor); Valluzzi, Regina (Inventor)

    2013-01-01

    One aspect of the present invention relates to a method of preparing a fibrous protein smectic hydrogel by way of a solvent templating process, comprising the steps of pouring an aqueous fibrous protein solution into a container comprising a solvent that is not miscible with water; sealing the container and allowing it to age at about room temperature; and collecting the resulting fibrous protein smectic hydrogel and allowing it to dry. Another aspect of the present invention relates to a method of obtaining predominantly one enantiomer from a racemic mixture, comprising the steps of pouring an aqueous fibrous protein solution into a container comprising a solvent that is not miscible with water; sealing the container and allowing it to age at about room temperature; allowing the enantiomers of racemic mixture to diffuse selectively into the smectic hydrogel in solution; removing the smectic hydrogel from the solution; rinsing predominantly one enantiomer from the surface of the smectic hydrogel; and extracting predominantly one enantiomer from the interior of the smectic hydrogel. The present invention also relates to a smectic hydrogel prepared according to an aforementioned method.

  7. Biomineralization Guided by Paper Templates

    PubMed Central

    Camci-Unal, Gulden; Laromaine, Anna; Hong, Estrella; Derda, Ratmir; Whitesides, George M.

    2016-01-01

    This work demonstrates the fabrication of partially mineralized scaffolds fabricated in 3D shapes using paper by folding, and by supporting deposition of calcium phosphate by osteoblasts cultured in these scaffolds. This process generates centimeter-scale free-standing structures composed of paper supporting regions of calcium phosphate deposited by osteoblasts. This work is the first demonstration that paper can be used as a scaffold to induce template-guided mineralization by osteoblasts. Because paper has a porous structure, it allows transport of O2 and nutrients across its entire thickness. Paper supports a uniform distribution of cells upon seeding in hydrogel matrices, and allows growth, remodelling, and proliferation of cells. Scaffolds made of paper make it possible to construct 3D tissue models easily by tuning material properties such as thickness, porosity, and density of chemical functional groups. Paper offers a new approach to study mechanisms of biomineralization, and perhaps ultimately new techniques to guide or accelerate the repair of bone. PMID:27277575

  8. Template synthesis and characterization of nanostructured lithium insertion electrodes and nanogold/porous aluminum oxide composite membranes

    NASA Astrophysics Data System (ADS)

    Patrissi, Charles John

    A membrane-based template synthesis method was used to prepare nanostructured Li-ion battery electrodes and nanogold/porous aluminum oxide composite membranes. Membrane-based template synthesis is a general method for the preparation of nanomaterials which entails deposition of the material of interest, or a suitable precursor, within the nanometer-diameter pores in a porous template membrane. This method allows for control of nanoparticle size and shape and is compatible with many methods of synthesis for bulk materials. The template membranes used in this work were commercially available porous polycarbonate filtration membranes and nanoporous aluminum oxide membranes that were prepared in-house. Nanostructured electrodes of orthorhombic V2O5, prepared using membrane-based template synthesis, were used to investigate the effects of Li-ion diffusion distance and V2O5 surface area on electrode rate capability. Nanowires of V2O5 were prepared by depositing a precursor in the pores of microporous polycarbonate filtration membranes. The result was an ensemble of 115 nm diameter, 2 mum long nanowires of V2O5 which protruded from a V 2O5 surface layer like the bristles of a brush. The Li + storage capacity of the nanostructured electrode was compared to a thin film control electrode at high discharge rates. Results show that the nanostructured electrode delivered three to four times the capacity of the thin film electrode at discharge rates above 500 C. A membrane based template synthesis method was also used to prepare crystalline V2O5 electrodes which have high volumetric charge capacities, at high discharge rates, compared to a thin-film control electrode. In order to obtain high volumetric rate capability, the as-received polycarbonate template membranes were chemically etched to increase membrane porosity. Nanofibrous electrodes of crystalline V2O5 were then prepared by depositing an alkoxide precursor in the pores of the etched membranes. Electrode volumetric

  9. Recycling nanowire templates for multiplex templating synthesis: a green and sustainable strategy.

    PubMed

    Wang, Jin-Long; Liu, Jian-Wei; Lu, Bing-Zhang; Lu, Yi-Ruo; Ge, Jin; Wu, Zhen-Yu; Wang, Zhi-Hua; Arshad, Muhammad Nadeem; Yu, Shu-Hong

    2015-03-23

    Template-directed synthesis of nanostructures has been emerging as one of the most important synthetic methodologies. A pristine nanotemplate is usually chemically transformed into other compounds and sacrificed after templating or only acts as an inert physical template to support the new components. If a nanotemplate is costly or toxic as waste, to recycle such a nanotemplate becomes highly desirable. Recently, ultrathin tellurium nanowires (TeNWs) have been demonstrated as versatile chemical or physical templates for the synthesis of a diverse family of uniform 1D nanostructures. However, ultrathin TeNWs as template are usually costly and are discarded as toxic waste in ionic species after chemical reactions or erosion. To solve the above problem, we conceptually demonstrate that such a nanotemplate can be economically recycled from waste solutions and repeatedly used as template.

  10. Preparation of Aluminum Nanomesh Thin Films from an Anodic Aluminum Oxide Template as Transparent Conductive Electrodes.

    PubMed

    Li, Yiwen; Chen, Yulong; Qiu, Mingxia; Yu, Hongyu; Zhang, Xinhai; Sun, Xiao Wei; Chen, Rui

    2016-01-01

    We have employed anodic aluminum oxide as a template to prepare ultrathin, transparent, and conducting Al films with a unique nanomesh structure for transparent conductive electrodes. The anodic aluminum oxide template is obtained through direct anodization of a sputtered Al layer on a glass substrate, and subsequent wet etching creates the nanomesh metallic film. The optical and conductive properties are greatly influenced by experimental conditions. By tuning the anodizing time, transparent electrodes with appropriate optical transmittance and sheet resistance have been obtained. The results demonstrate that our proposed strategy can serve as a potential method to fabricate low-cost TCEs to replace conventional indium tin oxide materials. PMID:26831759

  11. Preparation of Aluminum Nanomesh Thin Films from an Anodic Aluminum Oxide Template as Transparent Conductive Electrodes

    PubMed Central

    Li, Yiwen; Chen, Yulong; Qiu, Mingxia; Yu, Hongyu; Zhang, Xinhai; Sun, Xiao Wei; Chen, Rui

    2016-01-01

    We have employed anodic aluminum oxide as a template to prepare ultrathin, transparent, and conducting Al films with a unique nanomesh structure for transparent conductive electrodes. The anodic aluminum oxide template is obtained through direct anodization of a sputtered Al layer on a glass substrate, and subsequent wet etching creates the nanomesh metallic film. The optical and conductive properties are greatly influenced by experimental conditions. By tuning the anodizing time, transparent electrodes with appropriate optical transmittance and sheet resistance have been obtained. The results demonstrate that our proposed strategy can serve as a potential method to fabricate low-cost TCEs to replace conventional indium tin oxide materials. PMID:26831759

  12. Amesos2 Templated Direct Sparse Solver Package

    2011-05-24

    Amesos2 is a templated direct sparse solver package. Amesos2 provides interfaces to direct sparse solvers, rather than providing native solver capabilities. Amesos2 is a derivative work of the Trilinos package Amesos.

  13. Template-based prediction of protein function.

    PubMed

    Petrey, Donald; Chen, T Scott; Deng, Lei; Garzon, Jose Ignacio; Hwang, Howook; Lasso, Gorka; Lee, Hunjoong; Silkov, Antonina; Honig, Barry

    2015-06-01

    We discuss recent approaches for structure-based protein function annotation. We focus on template-based methods where the function of a query protein is deduced from that of a template for which both the structure and function are known. We describe the different ways of identifying a template. These are typically based on sequence analysis but new methods based on purely structural similarity are also being developed that allow function annotation based on structural relationships that cannot be recognized by sequence. The growing number of available structures of known function, improved homology modeling techniques and new developments in the use of structure allow template-based methods to be applied on a proteome-wide scale and in many different biological contexts. This progress significantly expands the range of applicability of structural information in function annotation to a level that previously was only achievable by sequence comparison.

  14. The Template: A Way To Control

    ERIC Educational Resources Information Center

    Schueneman, Margot

    1977-01-01

    When beginning students first attempt coil pots, there is a tendency to rely on the design of the coil to cover up any irregularities in form. One of the ways to help students see whether or not a form is getting away from then is to use a template. Explains and demonstrates how the contour of the template helps to guide the placement of the…

  15. Lipid bilayers on nano-templates

    DOEpatents

    Noy, Aleksandr; Artyukhin, Alexander B.; Bakajin, Olgica; Stoeve, Pieter

    2009-08-04

    A lipid bilayer on a nano-template comprising a nanotube or nanowire and a lipid bilayer around the nanotube or nanowire. One embodiment provides a method of fabricating a lipid bilayer on a nano-template comprising the steps of providing a nanotube or nanowire and forming a lipid bilayer around the polymer cushion. One embodiment provides a protein pore in the lipid bilayer. In one embodiment the protein pore is sensitive to specific agents

  16. Template Matching Using a Fluid Flow Model

    NASA Astrophysics Data System (ADS)

    Newman, William Curtis

    Template matching is successfully used in machine recognition of isolated spoken words. In these systems a word is broken into frames (20 millisecond time slices) and the spectral characteristics of each frame are found. Thus, each word is represented as a 2-dimensional (2-D) function of spectral characteristic and frame number. An unknown word is recognized by matching its 2-D representation to previously stored example words, or templates, also in this 2-D form. A new model for this matching step will be introduced. The 2-D representations of the template and unknown are used to determine the shape of a volume of viscous fluid. This volume is broken up into many small elements. The unknown is changed into the template by allowing flows between the element boundaries. Finally the match between the template and unknown is determined by calculating a weighted squared sum of the flow values. The model also allows the relative flow resistance between the element boundaries to be changed. This is useful for characterizing the important features of a given template. The flow resistances are changed according to the gradient of a simple performance function. This performance function is evaluated using a set of training samples provided by the user. The model is applied to isolated word and single character recognition tasks. Results indicate the applications where this model works best.

  17. Structural templates for comparative protein docking

    PubMed Central

    Anishchenko, Ivan; Kundrotas, Petras J.; Tuzikov, Alexander V.; Vakser, Ilya A.

    2014-01-01

    Structural characterization of protein-protein interactions is important for understanding life processes. Because of the inherent limitations of experimental techniques, such characterization requires computational approaches. Along with the traditional protein-protein docking (free search for a match between two proteins), comparative (template-based) modeling of protein-protein complexes has been gaining popularity. Its development puts an emphasis on full and partial structural similarity between the target protein monomers and the protein-protein complexes previously determined by experimental techniques (templates). The template-based docking relies on the quality and diversity of the template set. We present a carefully curated, non-redundant library of templates containing 4,950 full structures of binary complexes and 5,936 protein-protein interfaces extracted from the full structures at 12Å distance cut-off. Redundancy in the libraries was removed by clustering the PDB structures based on structural similarity. The value of the clustering threshold was determined from the analysis of the clusters and the docking performance on a benchmark set. High structural quality of the interfaces in the template and validation sets was achieved by automated procedures and manual curation. The library is included in the Dockground resource for molecular recognition studies at http://dockground.bioinformatics.ku.edu. PMID:25488330

  18. Structural templates for comparative protein docking.

    PubMed

    Anishchenko, Ivan; Kundrotas, Petras J; Tuzikov, Alexander V; Vakser, Ilya A

    2015-09-01

    Structural characterization of protein-protein interactions is important for understanding life processes. Because of the inherent limitations of experimental techniques, such characterization requires computational approaches. Along with the traditional protein-protein docking (free search for a match between two proteins), comparative (template-based) modeling of protein-protein complexes has been gaining popularity. Its development puts an emphasis on full and partial structural similarity between the target protein monomers and the protein-protein complexes previously determined by experimental techniques (templates). The template-based docking relies on the quality and diversity of the template set. We present a carefully curated, nonredundant library of templates containing 4950 full structures of binary complexes and 5936 protein-protein interfaces extracted from the full structures at 12 Å distance cut-off. Redundancy in the libraries was removed by clustering the PDB structures based on structural similarity. The value of the clustering threshold was determined from the analysis of the clusters and the docking performance on a benchmark set. High structural quality of the interfaces in the template and validation sets was achieved by automated procedures and manual curation. The library is included in the Dockground resource for molecular recognition studies at http://dockground.bioinformatics.ku.edu.

  19. Role of Amphiphilic Block Copolymer Composition on Pore Characteristics of Micelle-Templated Mesoporous Cobalt Oxide Films.

    PubMed

    Wang, Siyang; Tangvijitsakul, Pattarasai; Qiang, Zhe; Bhaway, Sarang M; Lin, Kehua; Cavicchi, Kevin A; Soucek, Mark D; Vogt, Bryan D

    2016-04-26

    Block copolymer templating is a versatile approach for the generation of well-defined porosity in a wide variety of framework chemistries. Here, we systematically investigate how the composition of a poly(methoxy poly[ethylene glycol] methacrylate)-block-poly(butyl acrylate) (PMPEG-PBA) template impacts the pore characteristics of mesoporous cobalt oxide films. Three templates with a constant PMPEG segment length and different hydrophilic block volume fractions of 17%, 51%, and 68% for the PMPEG-PBA are cooperatively assembled with cobalt nitrate hexahydrate and citric acid. Irrespective of template composition, a spherical nanostructure is templated and elliptical mesostructures are obtained on calcination due to uniaxial contraction of the film. The average pore size increases from 11.4 ± 2.8 to 48.5 ± 4.3 nm as the length of the PBA segment increases as determined from AFM. For all three templates examined, a maximum in porosity (∼35% in all cases) and surface area is obtained when the precursor solids contain 35-45 wt % PMPEG-PBA. This invariance suggests that the total polymer content drives the structure through interfacial assembly. The composition for maximizing porosity and surface area with the micelle-templating approach results from a general decrease in porosity with increasing cobalt nitrate hexahydrate content and the increasing mechanical integrity of the framework to resist collapse during template removal/crystallization as the cobalt nitrate hexahydrate content increases. Unlike typical evaporation induced self-assembly with sol-gel chemistry, the hydrophilic/hydrophobic composition of the block copolymer template is not a critical component to the mesostructure developed with micelle-templating using metal nitrate-citric acid as the precursor. PMID:27040316

  20. Mechanisms of Polymer-Templated Nanoparticle Synthesis: Contrasting ZnS and Au.

    PubMed

    Podhorska, Lucia; Delcassian, Derfogail; Goode, Angela E; Agyei, Michael; McComb, David W; Ryan, Mary P; Dunlop, Iain E

    2016-09-13

    We combine solution small-angle X-ray scattering (SAXS) and high-resolution analytical transmission electron microscopy (ATEM) to gain a full mechanistic understanding of substructure formation in nanoparticles templated by block copolymer reverse micelles, specifically poly(styrene)-block-poly(2-vinylpyridine). We report a novel substructure for micelle-templated ZnS nanoparticles, in which small crystallites (∼4 nm) exist within a larger (∼20 nm) amorphous organic-inorganic hybrid matrix. The formation of this complex structure is explained via SAXS measurements that characterize in situ for the first time the intermediate state of the metal-loaded micelle core: Zn(2+) ions are distributed throughout the micelle core, which solidifies as a unit on sulfidation. The nanoparticle size is thus determined by the radius of the metal-loaded core, rather than the quantity of available metal ions. This mechanism leads to particle size counterintuitively decreasing with increasing metal content, based on the modified interactions of the metal-complexed monomers in direct contrast to gold nanoparticles templated by the same polymer. PMID:27547996

  1. Synthesis of a mononuclear, non-square-planar chromium(ii) bis(alkoxide) complex and its reactivity toward organic carbonyls and CO2.

    PubMed

    Yousif, Maryam; Cabelof, Alyssa C; Martin, Philip D; Lord, Richard L; Groysman, Stanislav

    2016-06-14

    In this paper, we report the synthesis and reactivity of a rare mononuclear chromium(ii) bis(alkoxide) complex, Cr(OR')2(THF)2, that is supported by a new bulky alkoxide ligand (OR' = di-t-butyl-(3,5-diphenylphenyl)methoxide). The complex is prepared by protonolysis of square-planar Cr(N(SiMe3)2)2(THF)2 with HOR'. X-ray structure determination disclosed that Cr(OR')2(THF)2 features a distorted seesaw geometry, in contrast to nearly all other tetra-coordinate Cr(ii) complexes, which are square-planar. The reactivity of Cr(OR')2(THF)2 with aldehydes, ketones, and carbon dioxide was investigated. Treatment of Cr(OR')2(THF)2 with two equivalents of aromatic aldehydes ArCHO (ArCHO = benzaldehyde, 4-anisaldehyde, 4-trifluorbenzaldehyde, and 2,4,6-trimethylbenzaldehyde) leads cleanly to the formation of Cr(iv) diolate complexes Cr(OR')2(O2C2H2Ar2) that were characterized by UV-vis and IR spectroscopies and elemental analysis; the representative complex Cr(OR')2(O2C2H2Ph2) was characterized by X-ray crystallography. In contrast, no reductive coupling was observed for ketones: treatment of Cr(OR')2(THF)2 with one or two equivalents of benzophenone forms invariably a single ketone adduct Cr(OR')2(OCPh2) which does not react further. QM/MM calculations suggest the steric demands prevent ketone coupling, and demonstrate that a mononuclear Cr(iii) bis-aldehyde complex with partially reduced aldehydes is sufficient for C-C bond formation. The reaction of Cr(OR')2(THF)2 with CO2 leads to the insertion of CO2 into a Cr-OR' bond, followed by complex rearrangement to form a diamagnetic dinuclear paddlewheel complex Cr2(O2COR')4(THF)2, that was characterized by NMR, UV-vis, and IR spectroscopy, and X-ray crystallography. PMID:27073074

  2. Integration of molecular-layer-deposited aluminum alkoxide interlayers into inorganic nanolaminate barriers for encapsulation of organic electronics with improved stress resistance

    SciTech Connect

    Hossbach, Christoph Fischer, Dustin; Albert, Matthias; Bartha, Johann W.; Nehm, Frederik Klumbies, Hannes; Müller-Meskamp, Lars; Leo, Karl; Singh, Aarti; Richter, Claudia; Schroeder, Uwe; Mikolajick, Thomas

    2015-01-15

    Diffusion barrier stacks for the encapsulation of organic electronics made from inorganic nanolaminates of Al{sub 2}O{sub 3} and TiO{sub 2} with aluminum alkoxide interlayers have been deposited by atomic layer deposition (ALD) and molecular layer deposition (MLD). As a part of the MLD process development, the deposition of aluminum alkoxide with low a density of about 1.7 g/cm{sup 3} was verified. The ALD/MLD diffusion barrier stack is meant to be deposited either on a polymer film, creating a flexible barrier substrate, or on top of a device on glass, creating a thin-film encapsulation. In order to measure the water vapor transmission rate (WVTR) through the barrier, the device is replaced by a calcium layer acting as a water sensor in an electrical calcium test. For the barrier stack applied as thin-film encapsulation on glass substrates, high resolution scanning electron microscopy investigations indicate that the inorganic nanolaminates without MLD interlayers are brittle as they crack easily upon the stress induced by the corroding calcium below. The introduction of up to three MLD interlayers of 12 nm each into the 48 nm barrier film laminate successfully mitigates stress issues and prevents the barrier from cracking. Using the three MLD interlayer configurations on glass, WVTRs of as low as 10{sup −5} g/m{sup 2}/d are measured at 38 °C and 32% relative humidity. On polymer barrier substrates, the calcium is evaporated onto the barrier stack and encapsulated with a cavity glass. In this configuration, the corroding calcium has space for expansion and gas release without affecting the underlying barrier film. In consequence, a WVTR of about 3 × 10{sup −3} g/m{sup 2}/d is measured for all samples independently of the number of MLD interlayers. In conclusion, a stabilization and preservation of the ALD barrier film against mechanical stress is achieved by the introduction of MLD interlayers into the inorganic nanolaminate.

  3. Synthesis of a mononuclear, non-square-planar chromium(ii) bis(alkoxide) complex and its reactivity toward organic carbonyls and CO2.

    PubMed

    Yousif, Maryam; Cabelof, Alyssa C; Martin, Philip D; Lord, Richard L; Groysman, Stanislav

    2016-06-14

    In this paper, we report the synthesis and reactivity of a rare mononuclear chromium(ii) bis(alkoxide) complex, Cr(OR')2(THF)2, that is supported by a new bulky alkoxide ligand (OR' = di-t-butyl-(3,5-diphenylphenyl)methoxide). The complex is prepared by protonolysis of square-planar Cr(N(SiMe3)2)2(THF)2 with HOR'. X-ray structure determination disclosed that Cr(OR')2(THF)2 features a distorted seesaw geometry, in contrast to nearly all other tetra-coordinate Cr(ii) complexes, which are square-planar. The reactivity of Cr(OR')2(THF)2 with aldehydes, ketones, and carbon dioxide was investigated. Treatment of Cr(OR')2(THF)2 with two equivalents of aromatic aldehydes ArCHO (ArCHO = benzaldehyde, 4-anisaldehyde, 4-trifluorbenzaldehyde, and 2,4,6-trimethylbenzaldehyde) leads cleanly to the formation of Cr(iv) diolate complexes Cr(OR')2(O2C2H2Ar2) that were characterized by UV-vis and IR spectroscopies and elemental analysis; the representative complex Cr(OR')2(O2C2H2Ph2) was characterized by X-ray crystallography. In contrast, no reductive coupling was observed for ketones: treatment of Cr(OR')2(THF)2 with one or two equivalents of benzophenone forms invariably a single ketone adduct Cr(OR')2(OCPh2) which does not react further. QM/MM calculations suggest the steric demands prevent ketone coupling, and demonstrate that a mononuclear Cr(iii) bis-aldehyde complex with partially reduced aldehydes is sufficient for C-C bond formation. The reaction of Cr(OR')2(THF)2 with CO2 leads to the insertion of CO2 into a Cr-OR' bond, followed by complex rearrangement to form a diamagnetic dinuclear paddlewheel complex Cr2(O2COR')4(THF)2, that was characterized by NMR, UV-vis, and IR spectroscopy, and X-ray crystallography.

  4. Templated Synthesis of Silver(I) and Copper(II) Nanostructures: Solid State Reactions and Applications

    NASA Astrophysics Data System (ADS)

    Bourret, Gilles R.

    2011-12-01

    This Thesis presents the synthesis of novel 1D, 2D, and 3D Ag(I) and Cu(II) nanostructures and their use as sacrificial templates to make functional nanomaterials. New soft template methods were developed for the synthesis of AgCN and Cu(OH)2 nanostructures. Polymeric organic nanotubes were successfully used to synthesize AgCN nanowires, while the precipitation of Cu(OH)2 nanofibers was templated in water microdroplets. Both methods benefit from the versatility of soft templates and allows for a control of both the size and the morphology of the nanostructures produced. The conversion of these precursors into metallic and semi-conductive nanomaterials was achieved via chemical and electrochemical reduction, and thermolysis. Chemical reduction of the AgCN nanowires leads to the fabrication of conductive arrays on nylon filter substrates, while the thermolysis of the Cu(OH)2 spherical assemblies yields photoresponsive semi-conductive porous CuO spheres. The electrochemical reduction of the native Ag(I) and Cu(II) one-dimensional nanostructures was investigated in aqueous solution at gold/glass/gold junctions. The solid-solid conversion involved in the electrochemical reduction process was studied via cyclic voltammetry, chronoamperometry, and electronic microscopy. The strong influence of the reduction potential on the nanomaterials produced allowed for the fabrication of a range of Ag(0) nanostructures, including nanoparticles, nanoprisms, nanofibers and porous networks. Electrochemical reduction of Au/M2+/Au junctions leads to the formation of an excellent electrical contact between the two gold electrodes. This technique was expanded to include ionically-conductive Ag2S nanowires which form metallic/ionic-conductor heterojunctions. Keywords: nanostructure, nanowire, template, emulsion, electrochemistry, silver, cyanide, copper, oxide, heterojunction, sacrificial template.

  5. Conversion of Radiology Reporting Templates to the MRRT Standard.

    PubMed

    Kahn, Charles E; Genereaux, Brad; Langlotz, Curtis P

    2015-10-01

    In 2013, the Integrating the Healthcare Enterprise (IHE) Radiology workgroup developed the Management of Radiology Report Templates (MRRT) profile, which defines both the format of radiology reporting templates using an extension of Hypertext Markup Language version 5 (HTML5), and the transportation mechanism to query, retrieve, and store these templates. Of 200 English-language report templates published by the Radiological Society of North America (RSNA), initially encoded as text and in an XML schema language, 168 have been converted successfully into MRRT using a combination of automated processes and manual editing; conversion of the remaining 32 templates is in progress. The automated conversion process applied Extensible Stylesheet Language Transformation (XSLT) scripts, an XML parsing engine, and a Java servlet. The templates were validated for proper HTML5 and MRRT syntax using web-based services. The MRRT templates allow radiologists to share best-practice templates across organizations and have been uploaded to the template library to supersede the prior XML-format templates. By using MRRT transactions and MRRT-format templates, radiologists will be able to directly import and apply templates from the RSNA Report Template Library in their own MRRT-compatible vendor systems. The availability of MRRT-format reporting templates will stimulate adoption of the MRRT standard and is expected to advance the sharing and use of templates to improve the quality of radiology reports. PMID:25776768

  6. Conversion of Radiology Reporting Templates to the MRRT Standard.

    PubMed

    Kahn, Charles E; Genereaux, Brad; Langlotz, Curtis P

    2015-10-01

    In 2013, the Integrating the Healthcare Enterprise (IHE) Radiology workgroup developed the Management of Radiology Report Templates (MRRT) profile, which defines both the format of radiology reporting templates using an extension of Hypertext Markup Language version 5 (HTML5), and the transportation mechanism to query, retrieve, and store these templates. Of 200 English-language report templates published by the Radiological Society of North America (RSNA), initially encoded as text and in an XML schema language, 168 have been converted successfully into MRRT using a combination of automated processes and manual editing; conversion of the remaining 32 templates is in progress. The automated conversion process applied Extensible Stylesheet Language Transformation (XSLT) scripts, an XML parsing engine, and a Java servlet. The templates were validated for proper HTML5 and MRRT syntax using web-based services. The MRRT templates allow radiologists to share best-practice templates across organizations and have been uploaded to the template library to supersede the prior XML-format templates. By using MRRT transactions and MRRT-format templates, radiologists will be able to directly import and apply templates from the RSNA Report Template Library in their own MRRT-compatible vendor systems. The availability of MRRT-format reporting templates will stimulate adoption of the MRRT standard and is expected to advance the sharing and use of templates to improve the quality of radiology reports.

  7. Direct laser write (DLW) as a versatile tool in manufacturing templates for imprint lithography on flexible substrates

    NASA Astrophysics Data System (ADS)

    Ivan, Marius G.; Vaney, Jean-Baptiste; Verhaart, Dick; Meinders, Erwin

    2009-03-01

    A computer-controlled laser beam recorder with a wavelength of 405 nm has been employed for patterning the deposited resist with feature sizes varying from a few hundreds of nanometers to tens of micrometers. Four inch silicon templates for hot embossing source/ drain electrodes and metallic circuit for a disposable biosensor were obtained. SEM and optical microscopy reveal accurate transfer of developed photoresist structures into the underlying silicon wafer after plasma dry etching. Etch depths between 100 - 600 nm were obtained on the templates, and were further transferred into the imprinted plastic substrate and the metallic layer.

  8. Ion exchange properties of novel hydrous metal oxide materials

    SciTech Connect

    Gardner, T.J.; McLaughlin, L.I.

    1996-12-31

    Hydrous metal oxide (HMO) materials are inorganic ion exchangers which have many desirable characteristics for catalyst support applications, including high cation exchange capacity, anion exchange capability, high surface area, ease of adjustment of acidity and basicity, bulk or thin film preparation, and similar chemistry for preparation of various transition metal oxides. Cation exchange capacity is engineered into these materials through the uniform incorporation of alkali cations via manipulation of alkoxide chemistry. Specific examples of the effects of Na stoichiometry and the addition of SiO{sub 2} to hydrous titanium oxide (HTO) on ion exchange behavior will be given. Acid titration and cationic metal precursor complex exchange will be used to characterize the ion exchange behavior of these novel materials.

  9. Metallized Gelled Propellants Combustion Experiments in a Pulse Detonation Engine

    NASA Technical Reports Server (NTRS)

    Palaszewski, Bryan; Jurns, John; Breisacher, Kevin; Kearns, Kim

    2006-01-01

    A series of combustion tests were performed with metallized gelled JP 8/aluminum fuels in a Pulse Detonation Engine (PDE). Nanoparticles of aluminum were used in the 60 to 100 nanometer diameter. Gellants were also of a nanoparticulate type composed of hydrocarbon alkoxide materials. Using simulated air (a nitrogen-oxygen mixture), the ignition potential of metallized gelled fuels with nanoparticle aluminum was investigated. Ignition of the JP 8/aluminum was possible with less than or equal to a 23-wt% oxygen loading in the simulated air. JP 8 fuel alone was unable to ignite with less than 30 percent oxygen loaded simulated air. The tests were single shot tests of the metallized gelled fuel to demonstrate the capability of the fuel to improve fuel detonability. The tests were conducted at ambient temperatures and with maximal detonation pressures of 1340 psia.

  10. Synthesis of RNA oligomers on heterogeneous templates

    NASA Technical Reports Server (NTRS)

    Ertem, G.; Ferris, J. P.

    1996-01-01

    The concept of an RNA world in the chemical origin of life is appealing, as nucleic acids are capable of both information storage and acting as templates that catalyse the synthesis of complementary molecules. Template-directed synthesis has been demonstrated for homogeneous oligonucleotides that, like natural nucleic acids, have 3',5' linkages between the nucleotide monomers. But it seems likely that prebiotic routes to RNA-like molecules would have produced heterogeneous molecules with various kinds of phosphodiester linkages and both linear and cyclic nucleotide chains. Here we show that such heterogeneity need be no obstacle to the templating of complementary molecules. Specifically, we show that heterogeneous oligocytidylates, formed by the montmorillonite clay-catalysed condensation of actuated monomers, can serve as templates for the synthesis of oligoguanylates. Furthermore, we show that oligocytidylates that are exclusively 2',5'-linked can also direct synthesis of oligoguanylates. Such heterogeneous templating reactions could have increased the diversity of the pool of protonucleic acids from which life ultimately emerged.

  11. Automated Template Quantification for DNA Sequencing Facilities

    PubMed Central

    Ivanetich, Kathryn M.; Yan, Wilson; Wunderlich, Kathleen M.; Weston, Jennifer; Walkup, Ward G.; Simeon, Christian

    2005-01-01

    The quantification of plasmid DNA by the PicoGreen dye binding assay has been automated, and the effect of quantification of user-submitted templates on DNA sequence quality in a core laboratory has been assessed. The protocol pipets, mixes and reads standards, blanks and up to 88 unknowns, generates a standard curve, and calculates template concentrations. For pUC19 replicates at five concentrations, coefficients of variance were 0.1, and percent errors were from 1% to 7% (n = 198). Standard curves with pUC19 DNA were nonlinear over the 1 to 1733 ng/μL concentration range required to assay the majority (98.7%) of user-submitted templates. Over 35,000 templates have been quantified using the protocol. For 1350 user-submitted plasmids, 87% deviated by ≥ 20% from the requested concentration (500 ng/μL). Based on data from 418 sequencing reactions, quantification of user-submitted templates was shown to significantly improve DNA sequence quality. The protocol is applicable to all types of double-stranded DNA, is unaffected by primer (1 pmol/μL), and is user modifiable. The protocol takes 30 min, saves 1 h of technical time, and costs approximately $0.20 per unknown. PMID:16461949

  12. Variation of the shape and morphological properties of silica and metal oxide powders by electro homogeneous precipitation

    DOEpatents

    Harris, Michael T.; Basaran, Osman A.; Sisson, Warren G.; Brunson, Ronald R.

    1997-01-01

    The present invention provides a method for preparing irreversible linear aggregates (fibrils) of metal oxide powders by utilizing static or pulsed DC electrical fields across a relatively non-conducting liquid solvent in which organometal compounds or silicon alkoxides have been dissolved. The electric field is applied to the relatively non-conducting solution throughout the particle formation and growth process promoting the formation of either linear aggregates (fibrils) or spherical shaped particles as desired. Thus the present invention provides a physical method for altering the size, shape and porosity of precursor hydrous metal oxide or hydrous silicon oxide powders for the development of advanced ceramics with improved strength and insulating capacity.

  13. Chiral capillary electrophoresis applied to the determination of phenylglycidol enantiomers obtained from cinnamyl alcohol by asymmetric epoxidation using new titanium(IV) alkoxide compounds as catalysts.

    PubMed

    Morante-Zarcero, Sonia; Crego, Antonio L; Sierra, Isabel; Fajardo, Mariano; Marina, M Luisa

    2004-08-01

    A capillary electrophoresis method for the simultaneous determination of phenylglycidol enantiomers in the presence of an excess of cinnamyl alcohol was developed. The effects of the nature, pH and concentration of the buffer, the nature and concentration of chiral selector, the addition of methanol or acetonitrile, and the capillary temperature on the chiral resolution of phenylglycidol enantiomers were studied. Separations were achieved using 20 mM succinylated beta-cyclodextrin dissolved in a 10 mM borate buffer (pH 10.0). Chiral resolution for the phenylglycidol enantiomers in the optimized electrophoretic conditions was higher than 2.0 with an analysis time less than 7 min. The method developed was validated in terms of selectivity, linearity, precision (instrumental repeatability, method repeatability, intermediate precision), the limits of detection and quantitation, and accuracy. Limits of detection of 6.5 mg/L and 8.3 mg/L for (2S,3S)-(-)-3-phenylglycidol ((S,S)-PG) and (2R,3R)-(+)-3-phenylglycidol ((R,R)-PG), respectively, were obtained. The method was applied to study the asymmetric epoxidation of cinnamyl alcohol with titanium(IV) alkoxide compounds as catalysts in order to evaluate their catalytic activity and stereoselectivity of the epoxidation processes.

  14. Templated Control of Au nanospheres in Silica Nanowires

    SciTech Connect

    Tringe, J W; Vanamu, G; Zaidi, S H

    2007-03-15

    The formation of regularly-spaced metal nanostructures in selectively-placed insulating nanowires is an important step toward realization of a wide range of nano-scale electronic and opto-electronic devices. Here we report templated synthesis of Au nanospheres embedded in silica nanowires, with nanospheres consistently spaced with a period equal to three times their diameter. Under appropriate conditions, nanowires form exclusively on Si nanostructures because of enhanced local oxidation and reduced melting temperatures relative to templates with larger dimensions. We explain the spacing of the nanospheres with a general model based on a vapor-liquid-solid mechanism, in which an Au/Si alloy dendrite remains liquid in the nanotube until a critical Si concentration is achieved locally by silicon oxide-generated nanowire growth. Additional Si oxidation then locally reduces the surface energy of the Au-rich alloy by creating a new surface with minimum area inside of the nanotube. The isolated liquid domain subsequently evolves to become an Au nanosphere, and the process is repeated.

  15. Templated control of Au nanospheres in silica nanowires

    SciTech Connect

    Tringe, Joseph W.; Vanamu, Ganesh; Zaidi, Saleem H.

    2008-11-01

    The formation of regularly spaced metal nanostructures in selectively placed insulating nanowires is an important step toward realization of a wide range of nanoscale electronic and optoelectronic devices. Here we report templated synthesis of Au nanospheres embedded in silica nanowires, with nanospheres consistently spaced with a period equal to three times their diameter. Under appropriate conditions, nanowires form exclusively on Si nanostructures because of enhanced local oxidation and reduced melting temperatures relative to templates with larger dimensions. We explain the spacing of the nanospheres with a general model based on a vapor-liquid-solid mechanism, in which an Au/Si alloy dendrite remains liquid in the nanotube until a critical Si concentration is achieved locally by silicon oxide-generated nanowire growth. Additional Si oxidation then locally reduces the surface energy of the Au-rich alloy by creating a new surface with smaller area inside of the nanotube. The isolated liquid domain subsequently evolves to become an Au nanosphere, and the process is repeated.

  16. Fully Tunable Silicon Nanowire Arrays Fabricated by Soft Nanoparticle Templating.

    PubMed

    Rey, By Marcel; Elnathan, Roey; Ditcovski, Ran; Geisel, Karen; Zanini, Michele; Fernandez-Rodriguez, Miguel-Angel; Naik, Vikrant V; Frutiger, Andreas; Richtering, Walter; Ellenbogen, Tal; Voelcker, Nicolas H; Isa, Lucio

    2016-01-13

    We demonstrate a fabrication breakthrough to produce large-area arrays of vertically aligned silicon nanowires (VA-SiNWs) with full tunability of the geometry of the single nanowires and of the whole array, paving the way toward advanced programmable designs of nanowire platforms. At the core of our fabrication route, termed "Soft Nanoparticle Templating", is the conversion of gradually compressed self-assembled monolayers of soft nanoparticles (microgels) at a water-oil interface into customized lithographical masks to create VA-SiNW arrays by means of metal-assisted chemical etching (MACE). This combination of bottom-up and top-down techniques affords excellent control of nanowire etching site locations, enabling independent control of nanowire spacing, diameter and height in a single fabrication route. We demonstrate the fabrication of centimeter-scale two-dimensional gradient photonic crystals exhibiting continuously varying structural colors across the entire visible spectrum on a single silicon substrate, and the formation of tunable optical cavities supported by the VA-SiNWs, as unambiguously demonstrated through numerical simulations. Finally, Soft Nanoparticle Templating is combined with optical lithography to create hierarchical and programmable VA-SiNW patterns.

  17. UV Spectral Templates for High-Redshift Galaxies

    NASA Technical Reports Server (NTRS)

    Heap, Sara; Lindler, Don; Lanz, Thierry

    2003-01-01

    New instrumentation such as DEIMOS on Keck-II now enable deep spectral surveys, and thereby samples of galaxies at younger ages. At a redshift, z = 1, all galaxies are less than 6 Gyr old and hence, have not yet formed horizontal-branch stars. Also, at z = 1, the restframe-UV comes into view, and with it, a new set of spectral diagnostics. UV spectral features are especially important because most of the UV flux comes from stars at the main-sequence turnoff (MSTO). Hence, UV spectral diagnostics enable the ages of z = 1 galaxies to be estimated directly from MSTO stars. In preparation for these high-redshift spectral surveys, we are developing UV spectral templates for stellar populations younger than 6 Gyr using UV-optical spectra of stars observed by HST/STIS. We are also planning to supplement these observations with theoretical spectral grids of stars of various metallicities. In this paper, we present a progress report on the observation-based spectral templates and spectral diagnostics.

  18. Template-Stripped Smooth Ag Nanohole Arrays with Silica Shells for Surface Plasmon Resonance Biosensing

    PubMed Central

    Im, Hyungsoon; Lee, Si Hoon; Wittenberg, Nathan J.; Johnson, Timothy W.; Lindquist, Nathan C.; Nagpal, Prashant; Norris, David J.; Oh, Sang-Hyun

    2011-01-01

    Inexpensive, reproducible and high-throughput fabrication of nanometric apertures in metallic films can benefit many applications in plasmonics, sensing, spectroscopy, lithography and imaging. Here we use template stripping to pattern periodic nanohole arrays in optically thick, smooth Ag films with a silicon template made via nanoimprint lithography. Ag is a low-cost material with good optical properties, but it suffers from poor chemical stability and biocompatibility. However, a thin silica shell encapsulating our template-stripped Ag nanoholes facilitates biosensing applications by protecting the Ag from oxidation as well as providing a robust surface that can be readily modified with a variety of biomolecules using well-established silane chemistry. The thickness of the conformal silica shell can be precisely tuned by atomic layer deposition, and a 15-nm-thick silica shell can effectively prevent fluorophore quenching. The Ag nanohole arrays with silica shells can also be bonded to polydimethylsiloxane (PDMS) microfluidic channels for fluorescence imaging, formation of supported lipid bilayers, and real-time, label-free SPR sensing. Additionally, the smooth surfaces of the template-stripped Ag films enhance refractive index sensitivity compared with as-deposited, rough Ag films. Because nearly centimeter-sized nanohole arrays can be produced inexpensively without using any additional lithography, etching or lift-off, this method can facilitate widespread applications of metallic nanohole arrays for plasmonics and biosensing. PMID:21770414

  19. A multiple-template approach to protein threading.

    PubMed

    Peng, Jian; Xu, Jinbo

    2011-06-01

    Most threading methods predict the structure of a protein using only a single template. Due to the increasing number of solved structures, a protein without solved structure is very likely to have more than one similar template structures. Therefore, a natural question to ask is if we can improve modeling accuracy using multiple templates. This article describes a new multiple-template threading method to answer this question. At the heart of this multiple-template threading method is a novel probabilistic-consistency algorithm that can accurately align a single protein sequence simultaneously to multiple templates. Experimental results indicate that our multiple-template method can improve pairwise sequence-template alignment accuracy and generate models with better quality than single-template models even if they are built from the best single templates (P-value <10(-6)) while many popular multiple sequence/structure alignment tools fail to do so. The underlying reason is that our probabilistic-consistency algorithm can generate accurate multiple sequence/template alignments. In another word, without an accurate multiple sequence/template alignment, the modeling accuracy cannot be improved by simply using multiple templates to increase alignment coverage. Blindly tested on the CASP9 targets with more than one good template structures, our method outperforms all other CASP9 servers except two (Zhang-Server and QUARK of the same group). Our probabilistic-consistency algorithm can possibly be extended to align multiple protein/RNA sequences and structures.

  20. Transcriptional template activity of covalently modified DNA.

    PubMed

    Tolwińska-Stańczyk, Z; Wilmańska, D; Studzian, K; Gniazdowski, M

    1997-03-01

    The transcriptional template activity of covalent modified DNA is compared. 8-Methoxypsoralen (MOP), 3,4'dimethyl-8-methoxypsoralen (DMMOP) and benzopsoralen (BP) forming with DNA covalent complexes upon UV irradiation and exhibiting preference to pyrimidines, mostly thymines, differ in their cross-linking potency. MOP and DMMOP form both monoadducts and diadducts while no cross-links are formed by BP. Nitracrine (NC) forms covalent complexes with DNA upon reductive activation with dithiothreitol exhibiting a preference to purines and low cross-linking potency. Semilogarithmic plots of the relative template activity against the number of the drugs molecules covalently bound per 10(3) DNA nucleotides fit to regression lines corresponding to one-hit inactivation characteristics. The number of drug molecules decreasing RNA synthesis to 37% differ from 0.25 to 1.26 depending on the template used and the base preference but no dependence on the cross-linking potency was found. PMID:9067423

  1. Polyaniline nanowire synthesis templated by DNA

    NASA Astrophysics Data System (ADS)

    Nickels, Patrick; Dittmer, Wendy U.; Beyer, Stefan; Kotthaus, Jörg P.; Simmel, Friedrich C.

    2004-11-01

    DNA-templated polyaniline nanowires and networks are synthesized using three different methods. The resulting DNA/polyaniline hybrids are fully characterized using atomic force microscopy, UV-vis spectroscopy and current-voltage measurements. Oxidative polymerization of polyaniline at moderate pH values is accomplished using ammonium persulfate as an oxidant, or alternatively in an enzymatic oxidation by hydrogen peroxide using horseradish peroxidase, or by photo-oxidation using a ruthenium complex as photo-oxidant. Atomic force microscopy shows that all three methods lead to the preferential growth of polyaniline along DNA templates. With ammonium persulfate, polyaniline can be grown on DNA templates already immobilized on a surface. Current-voltage measurements are successfully conducted on DNA/polyaniline networks synthesized by the enzymatic method and the photo-oxidation method. The conductance is found to be consistent with values measured for undoped polyaniline films.

  2. Patterning and templating for nanoelectronics.

    PubMed

    Galatsis, Kosmas; Wang, Kang L; Ozkan, Mihri; Ozkan, Cengiz S; Huang, Yu; Chang, Jane P; Monbouquette, Harold G; Chen, Yong; Nealey, Paul; Botros, Youssry

    2010-02-01

    The semiconductor industry will soon be launching 32 nm complementary metal oxide semiconductor (CMOS) technology node using 193 nm lithography patterning technology to fabricate microprocessors with more than 2 billion transistors. To ensure the survival of Moore's law, alternative patterning techniques that offer advantages beyond conventional top-down patterning are aggressively being explored. It is evident that most alternative patterning techniques may not offer compelling advantages to succeed conventional top-down lithography for silicon integrated circuits, but alternative approaches may well indeed offer functional advantages in realising next-generation information processing nanoarchitectures such as those based on cellular, bioinsipired, magnetic dot logic, and crossbar schemes. This paper highlights and evaluates some patterning methods from the Center on Functional Engineered Nano Architectonics in Los Angeles and discusses key benchmarking criteria with respect to CMOS scaling.

  3. Biological doses with template distribution patterns

    SciTech Connect

    Harrop, R.; Haymond, H.R.; Nisar, A.; Syed, A.N.M.; Feder, B.H.; Neblett, D.L.

    1981-02-01

    Consideration of radiation dose rate effects emphasizes advantages of the template method for lateral distribution of multiple sources in treatment of laterally infiltrating gynecologic cancer, when compared to a conventional technique with colpostats. Biological doses in time dose fractionation (TDF), ret and reu units are calculated for the two treatment methods. With the template method the lateral dose (point B) is raised without significantly increasing the doses to the rectum and bladder, that is, relatively, the calculated biological doses at point A and B are more nearly equivalent and the doses to the rectum and bladder are significantly lower than the dose to point B.

  4. Affordance Templates for Shared Robot Control

    NASA Technical Reports Server (NTRS)

    Hart, Stephen; Dinh, Paul; Hambuchen, Kim

    2014-01-01

    This paper introduces the Affordance Template framework used to supervise task behaviors on the NASA-JSC Valkyrie robot at the 2013 DARPA Robotics Challenge (DRC) Trials. This framework provides graphical interfaces to human supervisors that are adjustable based on the run-time environmental context (e.g., size, location, and shape of objects that the robot must interact with, etc.). Additional improvements, described below, inject degrees of autonomy into instantiations of affordance templates at run-time in order to enable efficient human supervision of the robot for accomplishing tasks.

  5. Preparation of porous lanthanum phosphate with templates

    SciTech Connect

    Onoda, Hiroaki; Ishima, Yuya; Takenaka, Atsushi; Tanaka, Isao

    2009-08-05

    Malonic acid, propionic acid, glycine, n-butylamine, and urea were added to the preparation of lanthanum phosphate from lanthanum nitrate and phosphoric acid solutions. All additives were taken into lanthanum phosphate particles. The additives that have a basic site were easy to contain in precipitates. The addition of templates improved the specific surface area of lanthanum phosphate. The amount of pore, with radius smaller than 4 nm, increased with the addition of templates. The remained additives had influence on the acidic properties of lanthanum phosphate.

  6. Stochastic template placement algorithm for gravitational wave data analysis

    SciTech Connect

    Harry, I. W.; Sathyaprakash, B. S.; Allen, B.

    2009-11-15

    This paper presents an algorithm for constructing matched-filter template banks in an arbitrary parameter space. The method places templates at random, then removes those which are 'too close' together. The properties and optimality of stochastic template banks generated in this manner are investigated for some simple models. The effectiveness of these template banks for gravitational wave searches for binary inspiral waveforms is also examined. The properties of a stochastic template bank are then compared to the deterministically placed template banks that are currently used in gravitational wave data analysis.

  7. Core-shell-corona polymeric micelles as a versatile template for synthesis of inorganic hollow nanospheres.

    PubMed

    Sasidharan, Manickam; Nakashima, Kenichi

    2014-01-21

    shell structures-that allow fabrication of a variety of hollow nanoparticles. Importantly, we synthesized all of these particles in water, avoiding use of hazardous organic solvents. We have designed the precursor of the inorganic material to be selectively sorbed into the shell domain, leaving the corona free from the inorganic precursors that would destabilize the micelle. The core, meanwhile, is the template for the formation of the hollow void. By rationally tailoring experimental parameters, we readily and selectively obtained a variety of hollow nanoparticles including silica, hybrid silicas, metal-oxides, metal-carbonates, metal-sulfates, metal-borates, and metal-phosphates. Finally, we highlight the state-of-the-art techniques we used to characterize these nanoparticles, and describe experiments that demonstrate the potential of these hollow particles in drug delivery, and as anode and cathode materials for lithium-ion batteries.

  8. Template synthesis and characterization of carbon nanomaterials from ferrocene crystals

    NASA Astrophysics Data System (ADS)

    Cherkasov, Nikolay; Savilov, Serguei V.; Ivanov, Anton S.; Egorov, Alex V.; Lunin, Valery V.; Ibhadon, Alex O.

    2014-07-01

    Filamentous ribbon-like structures of highly disordered carbon of thickness 10-100 nm built from merged individual carbon nanofibers were synthesised by chemical vapour deposition from saturated ferrocene-benzene solution at 950 K. The materials obtained were characterized by electron microscopy, x-ray and electron diffraction, Raman spectroscopy and a possible growth mechanism for their formation was proposed and discussed. The synthesis demonstrates the possibility of a template growth of carbon nanomaterials and supports the vapour-solid-solid growth model of carbon materials because the catalysing metal particles are solid under the experimental conditions. Due to the large number of structural defects, filamentous structure, submicrometer thickness and low intraparticle diffusion of the nanomaterials, they can find application in catalysis as catalyst supports and sorbents.

  9. Shaping and patterning gold nanoparticles via micelle templated photochemistry.

    PubMed

    Kundrat, F; Baffou, G; Polleux, J

    2015-10-14

    Shaping and positioning noble metal nanostructures are essential processes that still require laborious and sophisticated techniques to fabricate functional plasmonic interfaces. The present study reports a simple photochemical approach compatible with micellar nanolithography and photolithography that enables the growth, arrangement and shaping of gold nanoparticles with tuneable plasmonic resonances on glass substrates. Ultraviolet illumination of surfaces coated with gold-loaded micelles leads to the formation of gold nanoparticles with micro/nanometric spatial resolution without requiring any photosensitizers or photoresists. Depending on the extra-micellar chemical environment and the illumination wavelength, block copolymer micelles act as reactive and light-responsive templates, which enable to grow gold deformed nanoparticles (potatoids) and nanorings. Optical characterization reveals that arrays of individual potatoids and rings feature a localized plasmon resonance around 600 and 800 nm, respectively, enhanced photothermal properties and high temperature sustainability, making them ideal platforms for future developments in nanochemistry and biomolecular manipulation controlled by near-infrared-induced heat.

  10. The biogeochemical cycle of the adsorbed template. II - Selective adsorption of mononucleotides on adsorbed polynucleotide templates

    NASA Technical Reports Server (NTRS)

    Lazard, Daniel; Lahav, Noam; Orenberg, James B.

    1988-01-01

    Experimental results are presented for the verification of the specific interaction step of the 'adsorbed template' biogeochemical cycle, a simple model for a primitive prebiotic replication system. The experimental system consisted of gypsum as the mineral to which an oligonucleotide template attaches (Poly-C or Poly-U) and (5-prime)-AMP, (5-prime)-GMP, (5-prime)-CMP and (5-prime)-UMP as the interacting biomonomers. When Poly-C or Poly-U were used as adsorbed templates, (5-prime)-GMP and (5-prime)-AMP, respectively, were observed to be the most strongly adsorbed species.

  11. Structural interconnections and the role of heptagonal rings in endohedral trimetallic nitride template fullerenes.

    PubMed

    Gan, Li-Hua; Lei, Dan; Fowler, Patrick W

    2016-07-01

    Recent experiments indicate that fullerene isomers outside the classical definition can also encapsulate metallic atoms or clusters to form endohedral metallofullerenes. Our systematic study using DFT calculations, suggests that many heptagon-including nonclassical trimetallic nitride template fullerenes are similar in stability to their classical counterparts, and that conversion between low-energy nonclassical and classical parent cages via Endo-Kroto insertion/extrusion of C2 units and Stone-Wales isomerization may facilitate the formation of endohedral trimetallic nitride fullerenes. Close structural connections are found between favored isomers of trimetallic nitride template fullerenes from C78 to C82 . It appears that the lower symmetry and local deformations associated with introduction of a heptagonal ring favor encapsulation of intrinsically less symmetrical mixed metal nitride clusters. © 2016 Wiley Periodicals, Inc. PMID:27282122

  12. Hollow ZIF-8 Nanoworms from Block Copolymer Templates.

    PubMed

    Yu, Haizhou; Qiu, Xiaoyan; Neelakanda, Pradeep; Deng, Lin; Khashab, Niveen M; Nunes, Suzana P; Peinemann, Klaus-Viktor

    2015-01-01

    Recently two quite different types of "nano-containers" have been recognized as attractive potential drug carriers; these are wormlike filamenteous micelles ("filomicelles") on the one hand and metal organic frameworks on the other hand. In this work we combine these two concepts. We report for the first time the manufacturing of metal organic framework nanotubes with a hollow core. These worm-like tubes are about 200 nm thick and several μm long. The preparation is simple: we first produce long and flexible filament-shaped micelles by block copolymer self-assembly. These filomicelles serve as templates to grow a very thin layer of interconnected ZIF-8 crystals on their surface. Finally the block copolymer is removed by solvent extraction and the hollow ZIF-8 nanotubes remain. These ZIF-NTs are surprisingly stable and withstand purification by centrifugation. The synthesis method is straightforward and can easily be applied for other metal organic framework materials. The ZIF-8 NTs exhibit high loading capacity for the model anti cancer drug doxorubicin (DOX) with a pH-triggered release. Hence, a prolonged circulation in the blood stream and a targeted drug release behavior can be expected.

  13. Hollow ZIF-8 Nanoworms from Block Copolymer Templates

    PubMed Central

    Yu, Haizhou; Qiu, Xiaoyan; Neelakanda, Pradeep; Deng, Lin; Khashab, Niveen M.; Nunes, Suzana P.; Peinemann, Klaus-Viktor

    2015-01-01

    Recently two quite different types of “nano-containers” have been recognized as attractive potential drug carriers; these are wormlike filamenteous micelles (“filomicelles”) on the one hand and metal organic frameworks on the other hand. In this work we combine these two concepts. We report for the first time the manufacturing of metal organic framework nanotubes with a hollow core. These worm-like tubes are about 200 nm thick and several μm long. The preparation is simple: we first produce long and flexible filament-shaped micelles by block copolymer self-assembly. These filomicelles serve as templates to grow a very thin layer of interconnected ZIF-8 crystals on their surface. Finally the block copolymer is removed by solvent extraction and the hollow ZIF-8 nanotubes remain. These ZIF-NTs are surprisingly stable and withstand purification by centrifugation. The synthesis method is straightforward and can easily be applied for other metal organic framework materials. The ZIF-8 NTs exhibit high loading capacity for the model anti cancer drug doxorubicin (DOX) with a pH-triggered release. Hence, a prolonged circulation in the blood stream and a targeted drug release behavior can be expected. PMID:26471862

  14. Catalytic Ester–Amide Exchange Using Group (IV) Metal Alkoxide–Activator Complexes

    PubMed Central

    Han, Chong; Lee, Jonathan P.; Lobkovsky, Emil; Porco, John A.

    2005-01-01

    A process for preparation of amides from unactivated esters and amines has been developed using a catalytic system comprised of group (IV) metal alkoxides in conjunction with additives including 1-hydroxy-7-azabenzotriazole (HOAt). In general, ester–amide exchange proceeds using a variety of structurally diverse esters and amines without azeotropic reflux to remove the alcohol byproduct. Initial mechanistic studies on the Zr(Ot-Bu)4–HOAt system revealed that the active catalyst is a novel, dimeric zirconium complex as determined by X-ray crystallography. PMID:16011366

  15. A lightweight approach for biometric template protection

    NASA Astrophysics Data System (ADS)

    Al-Assam, Hisham; Sellahewa, Harin; Jassim, Sabah

    2009-05-01

    Privacy and security are vital concerns for practical biometric systems. The concept of cancelable or revocable biometrics has been proposed as a solution for biometric template security. Revocable biometric means that biometric templates are no longer fixed over time and could be revoked in the same way as lost or stolen credit cards are. In this paper, we describe a novel and an efficient approach to biometric template protection that meets the revocability property. This scheme can be incorporated into any biometric verification scheme while maintaining, if not improving, the accuracy of the original biometric system. However, we shall demonstrate the result of applying such transforms on face biometric templates and compare the efficiency of our approach with that of the well-known random projection techniques. We shall also present the results of experimental work on recognition accuracy before and after applying the proposed transform on feature vectors that are generated by wavelet transforms. These results are based on experiments conducted on a number of well-known face image databases, e.g. Yale and ORL databases.

  16. Electrochemical synthesis on single cells as templates.

    PubMed

    Tam, Jasper; Salgado, Shehan; Miltenburg, Mark; Maheshwari, Vivek

    2013-10-01

    The cell surface is made electrochemically active by interfacing with graphene sheets. The electrical and thermal properties of graphene allow the control of cell surface potential for electrochemical synthesis. Using this approach radially projecting ZnO nanorods are templated on the surface of single cells. This reported single cell photosensor has superior performance than similar devices made on planar surfaces.

  17. Photon signature analysis using template matching

    NASA Astrophysics Data System (ADS)

    Bradley, D. A.; Hashim, S.; Saripan, M. I.; Wells, K.; Dunn, W. L.

    2011-10-01

    We describe an approach to detect improvised explosive devices (IEDs) by using a template matching procedure. This approach relies on the signature due to backstreaming γ photons from various targets. In this work we have simulated cylindrical targets of aluminum, iron, copper, water and ammonium nitrate (nitrogen-rich fertilizer). We simulate 3.5 MeV source photons distributed on a plane inside a shielded area using Monte Carlo N-Particle (MCNP TM) code version 5 (V5). The 3.5 MeV source gamma rays yield 511 keV peaks due to pair production and scattered gamma rays. In this work, we simulate capture of those photons that backstream, after impinging on the target element, toward a NaI detector. The captured backstreamed photons are expected to produce a unique spectrum that will become part of a simple signal processing recognition system based on the template matching method. Different elements were simulated using different sets of random numbers in the Monte Carlo simulation. To date, the sum of absolute differences (SAD) method has been used to match the template. In the examples investigated, template matching was found to detect all elements correctly.

  18. Stacked subsea templates accelerate deepwater development

    SciTech Connect

    Ramsey, J.F.; Blincow, R.M.; Pickard, R.D. )

    1991-10-21

    This paper reports on a deepwater project that can be brought on-line more quickly because of stackable drilling and production templates. Historically, one of the primary barriers to the economic development of deepwater reserves has been the long lead time from discovery to first production. Typically, production facilities must be built and often installed before development wells are drilled. The use of three-slot drilling templates allows development drilling to proceed while the production templates, Christmas trees, flow lines, and production platform are constructed. Thus, the time from initial investment to first revenue reduced. Enserch Exploration Inc., along with partners Petrofina Delaware Inc. and AGIP Petroleum, is using a piggy-back or transportable stacked template system to develop deepwater gas reserves in Mississippi Canyon Block 441, approximately 50 miles south of Grand Isle, La. The discovery is located in 1,410-1,520 ft of water. The Louisiana Offshore Oil Port (LOOP) safety fairway running north to south covers the eastern three fourths of Mississippi Canyon Block 441 and rules out surface production facilities over the well locations.

  19. Engineering topochemical polymerizations using block copolymer templates.

    PubMed

    Zhu, Liangliang; Tran, Helen; Beyer, Frederick L; Walck, Scott D; Li, Xin; Agren, Hans; Killops, Kato L; Campos, Luis M

    2014-09-24

    With the aim to achieve rapid and efficient topochemical polymerizations in the solid state, via solution-based processing of thin films, we report the integration of a diphenyldiacetylene monomer and a poly(styrene-b-acrylic acid) block copolymer template for the generation of supramolecular architectural photopolymerizable materials. This strategy takes advantage of non-covalent interactions to template a topochemical photopolymerization that yields a polydiphenyldiacetylene (PDPDA) derivative. In thin films, it was found that hierarchical self-assembly of the diacetylene monomers by microphase segregation of the block copolymer template enhances the topochemical photopolymerization, which is complete within a 20 s exposure to UV light. Moreover, UV-active cross-linkable groups were incorporated within the block copolymer template to create micropatterns of PDPDA by photolithography, in the same step as the polymerization reaction. The materials design and processing may find potential uses in the microfabrication of sensors and other important areas that benefit from solution-based processing of flexible conjugated materials. PMID:25208609

  20. Visual cluster analysis and pattern recognition template and methods

    SciTech Connect

    Osbourn, G.C.; Martinez, R.F.

    1993-12-31

    This invention is comprised of a method of clustering using a novel template to define a region of influence. Using neighboring approximation methods, computation times can be significantly reduced. The template and method are applicable and improve pattern recognition techniques.

  1. Computational templates for introductory nuclear science using mathcad

    NASA Astrophysics Data System (ADS)

    Sarantites, D. G.; Sobotka, L. G.

    2013-01-01

    Computational templates used to teach an introductory course in nuclear chemistry and physics at Washington University in St. Louis are presented in brief. The templates cover both basic and applied topics.

  2. Visual cluster analysis and pattern recognition template and methods

    DOEpatents

    Osbourn, Gordon Cecil; Martinez, Rubel Francisco

    1999-01-01

    A method of clustering using a novel template to define a region of influence. Using neighboring approximation methods, computation times can be significantly reduced. The template and method are applicable and improve pattern recognition techniques.

  3. Visual cluster analysis and pattern recognition template and methods

    DOEpatents

    Osbourn, G.C.; Martinez, R.F.

    1999-05-04

    A method of clustering using a novel template to define a region of influence is disclosed. Using neighboring approximation methods, computation times can be significantly reduced. The template and method are applicable and improve pattern recognition techniques. 30 figs.

  4. Templated Self Assemble of Nano-Structures

    SciTech Connect

    Suo, Zhigang

    2013-04-29

    This project will identify and model mechanisms that template the self-assembly of nanostructures. We focus on a class of systems involving a two-phase monolayer of molecules adsorbed on a solid surface. At a suitably elevated temperature, the molecules diffuse on the surface to reduce the combined free energy of mixing, phase boundary, elastic field, and electrostatic field. With no template, the phases may form a pattern of stripes or disks. The feature size is on the order of 1-100 nm, selected to compromise the phase boundary energy and the long-range elastic or electrostatic interaction. Both experimental observations and our theoretical simulations have shown that the pattern resembles a periodic lattice, but has abundant imperfections. To form a perfect periodic pattern, or a designed aperiodic pattern, one must introduce a template to guide the assembly. For example, a coarse-scale pattern, lithographically defined on the substrate, will guide the assembly of the nanoscale pattern. As another example, if the molecules on the substrate surface carry strong electric dipoles, a charged object, placed in the space above the monolayer, will guide the assembly of the molecular dipoles. In particular, the charged object can be a mask with a designed nanoscale topographic pattern. A serial process (e.g., e-beam lithography) is necessary to make the mask, but the pattern transfer to the molecules on the substrate is a parallel process. The technique is potentially a high throughput, low cost process to pattern a monolayer. The monolayer pattern itself may serve as a template to fabricate a functional structure. This project will model fundamental aspects of these processes, including thermodynamics and kinetics of self-assembly, templated self-assembly, and self-assembly on unconventional substrates. It is envisioned that the theory will not only explain the available experimental observations, but also motivate new experiments.

  5. Damage free integration of ultralow-k dielectrics by template replacement approach

    SciTech Connect

    Zhang, L.; De Gendt, S.; Marneffe, J.-F. de; Heylen, N.; Murdoch, G.; Tokei, Z.; Boemmels, J.; Baklanov, M. R.

    2015-08-31

    Cu/low-k integration by conventional damascene approach is becoming increasingly difficult as critical dimensions scale down. An alternative integration scheme is studied based on the replacement of a sacrificial template by ultralow-k dielectric. A metal structure is first formed by patterning a template material. After template removal, a k = 2.31 spin-on type of porous low-k dielectric is deposited onto the patterned metal lines. The chemical and electrical properties of spin-on dielectrics are studied on blanket wafers, indicating that during hard bake, most porogen is removed within few minutes, but 120 min are required to achieve the lowest k-value. The effective dielectric constant of the gap-fill low-k is investigated on a 45 nm ½ pitch Meander-Fork structure, leading to k{sub eff} below 2.4. The proposed approach solves the two major challenges in conventional Cu/low-k damascene integration approach: low-k plasma damage and metal penetration during barrier deposition on porous materials.

  6. Damage free integration of ultralow-k dielectrics by template replacement approach

    NASA Astrophysics Data System (ADS)

    Zhang, L.; de Marneffe, J.-F.; Heylen, N.; Murdoch, G.; Tokei, Z.; Boemmels, J.; De Gendt, S.; Baklanov, M. R.

    2015-08-01

    Cu/low-k integration by conventional damascene approach is becoming increasingly difficult as critical dimensions scale down. An alternative integration scheme is studied based on the replacement of a sacrificial template by ultralow-k dielectric. A metal structure is first formed by patterning a template material. After template removal, a k = 2.31 spin-on type of porous low-k dielectric is deposited onto the patterned metal lines. The chemical and electrical properties of spin-on dielectrics are studied on blanket wafers, indicating that during hard bake, most porogen is removed within few minutes, but 120 min are required to achieve the lowest k-value. The effective dielectric constant of the gap-fill low-k is investigated on a 45 nm ½ pitch Meander-Fork structure, leading to keff below 2.4. The proposed approach solves the two major challenges in conventional Cu/low-k damascene integration approach: low-k plasma damage and metal penetration during barrier deposition on porous materials.

  7. Graded porous inorganic materials derived from self-assembled block copolymer templates

    NASA Astrophysics Data System (ADS)

    Gu, Yibei; Werner, Jörg G.; Dorin, Rachel M.; Robbins, Spencer W.; Wiesner, Ulrich

    2015-03-01

    Graded porous inorganic materials directed by macromolecular self-assembly are expected to offer unique structural platforms relative to conventional porous inorganic materials. Their preparation to date remains a challenge, however, based on the sparsity of viable synthetic self-assembly pathways to control structural asymmetry. Here we demonstrate the fabrication of graded porous carbon, metal, and metal oxide film structures from self-assembled block copolymer templates by using various backfilling techniques in combination with thermal treatments for template removal and chemical transformations. The asymmetric inorganic structures display mesopores in the film top layers and a gradual pore size increase along the film normal in the macroporous sponge-like support structure. Substructure walls between macropores are themselves mesoporous, constituting a structural hierarchy in addition to the pore gradation. Final graded structures can be tailored by tuning casting conditions of self-assembled templates as well as the backfilling processes. We expect that these graded porous inorganic materials may find use in applications including separation, catalysis, biomedical implants, and energy conversion and storage.Graded porous inorganic materials directed by macromolecular self-assembly are expected to offer unique structural platforms relative to conventional porous inorganic materials. Their preparation to date remains a challenge, however, based on the sparsity of viable synthetic self-assembly pathways to control structural asymmetry. Here we demonstrate the fabrication of graded porous carbon, metal, and metal oxide film structures from self-assembled block copolymer templates by using various backfilling techniques in combination with thermal treatments for template removal and chemical transformations. The asymmetric inorganic structures display mesopores in the film top layers and a gradual pore size increase along the film normal in the macroporous sponge

  8. Reactive landing of gas-phase ions as a tool for the fabrication of metal oxide surfaces for in situ phosphopeptide enrichment.

    PubMed

    Blacken, Grady R; Volný, Michael; Diener, Matthew; Jackson, Karl E; Ranjitkar, Pratistha; Maly, Dustin J; Turecek, Frantisek

    2009-06-01

    Zirconium, titanium, and hafnium oxide-coated stainless steel surfaces are fabricated by reactive landing of gas-phase ions produced by electrospray ionization of group IVB metal alkoxides. The surfaces are used for in situ enrichment of phosphopeptides before analysis by matrix-assisted laser desorption ionization (MALDI) mass spectrometry. To evaluate this method we characterized ZrO(2) (zirconia) surfaces by (1) comparison with the other group IVB metal oxides of TiO(2) (titania) and HfO(2) (hafnia), (2) morphological characterization by SEM image analysis, and (3) dependence of phosphopeptide enrichment on the metal oxide layer thickness. Furthermore, we evaluated the necessity of the reactive landing process for the construction of useful metal oxide surfaces by preparing surfaces by electrospray deposition of Zr, Ti, and Hf alkoxides directly onto polished metal surfaces at atmospheric pressure. Although all three metal oxide surfaces evaluated were capable of phosphopeptide enrichment from complex peptide mixtures, zirconia performed better than hafnia or titania as a result of morphological characteristics illustrated by the SEM analysis. Metal oxide coatings that were fabricated by atmospheric pressure deposition were still capable of in situ phosphopeptide enrichment, although with inferior efficiency and surface durability. We show that zirconia surfaces prepared by reactive landing of gas-phase ions can be a useful tool for high throughput screening of novel phosphorylation sites and quantitation of phosphorylation kinetics.

  9. Direct shape control of photoreduced nanostructures on proton exchanged ferroelectric templates

    NASA Astrophysics Data System (ADS)

    Balobaid, Laila; Craig Carville, N.; Manzo, Michele; Gallo, Katia; Rodriguez, Brian J.

    2013-01-01

    Photoreduction on a periodically proton exchanged ferroelectric crystal leads to the formation of periodic metallic nanostructures on the surface. By varying the depth of the proton exchange (PE) from 0.59 to 3.10 μm in congruent lithium niobate crystals, the width of the lateral diffusion region formed by protons diffusing under the mask layer can be controlled. The resulting deposition occurs in the PE region with the shallowest PE depth and preferentially in the lateral diffusion region for greater PE depths. PE depth-control provides a route for the fabrication of complex metallic nanostructures with controlled dimensions on chemically patterned ferroelectric templates.

  10. Incorporation of Cobalt‐Cyclen Complexes into Templated Nanogels Results in Enhanced Activity

    PubMed Central

    Jorge, Ana Rita; Chernobryva, Mariya; Rigby, Stephen E. J.

    2015-01-01

    Abstract Recent advances in nanomaterials have identified nanogels as an excellent matrix for novel biomimetic catalysts using the molecular imprinting approach. Polymerisable Co‐cyclen complexes with phosphonate and carbonate templates have been prepared, fully characterised and used to obtain nanogels that show high activity and turnover with low catalytic load, compared to the free complex, in the hydrolysis of 4‐nitrophenyl phosphate, a nerve agent simulant. This work demonstrates that the chemical structure of the template has an impact on the coordination geometry and oxidation state of the metal centre in the polymerisable complex resulting in very significant changes in the catalytic properties of the polymeric matrix. Both pseudo‐octahedral cobalt(III) and trigonal‐bipyramidal cobalt(II) structures have been used for the synthesis of imprinted nanogels, and the catalytic data demonstrate that: i) the imprinted nanogels can be used in 15 % load and show turnover; ii) the structural differences in the polymeric matrices resulting from the imprinting approach with different templates are responsible for the molecular recognition capabilities and the catalytic activity. Nanogel P1, imprinted with the carbonate template, shows >50 % higher catalytic activity than P2 imprinted with the phosphonate. PMID:26661923

  11. A TSR Visual Servoing System Based on a Novel Dynamic Template Matching Method.

    PubMed

    Cai, Jia; Huang, Panfeng; Zhang, Bin; Wang, Dongke

    2015-01-01

    The so-called Tethered Space Robot (TSR) is a novel active space debris removal system. To solve its problem of non-cooperative target recognition during short-distance rendezvous events, this paper presents a framework for a real-time visual servoing system using non-calibrated monocular-CMOS (Complementary Metal Oxide Semiconductor). When a small template is used for matching with a large scene, it always leads to mismatches, so a novel template matching algorithm to solve the problem is presented. Firstly, the novel matching algorithm uses a hollow annulus structure according to a FAST (Features from Accelerated Segment) algorithm and makes the method be rotation-invariant. Furthermore, the accumulative deviation can be decreased by the hollow structure. The matching function is composed of grey and gradient differences between template and object image, which help it reduce the effects of illumination and noises. Then, a dynamic template update strategy is designed to avoid tracking failures brought about by wrong matching or occlusion. Finally, the system synthesizes the least square integrated predictor, realizing tracking online in complex circumstances. The results of ground experiments show that the proposed algorithm can decrease the need for sophisticated computation and improves matching accuracy. PMID:26703609

  12. A TSR Visual Servoing System Based on a Novel Dynamic Template Matching Method †

    PubMed Central

    Cai, Jia; Huang, Panfeng; Zhang, Bin; Wang, Dongke

    2015-01-01

    The so-called Tethered Space Robot (TSR) is a novel active space debris removal system. To solve its problem of non-cooperative target recognition during short-distance rendezvous events, this paper presents a framework for a real-time visual servoing system using non-calibrated monocular-CMOS (Complementary Metal Oxide Semiconductor). When a small template is used for matching with a large scene, it always leads to mismatches, so a novel template matching algorithm to solve the problem is presented. Firstly, the novel matching algorithm uses a hollow annulus structure according to a FAST (Features from Accelerated Segment) algorithm and makes the method be rotation-invariant. Furthermore, the accumulative deviation can be decreased by the hollow structure. The matching function is composed of grey and gradient differences between template and object image, which help it reduce the effects of illumination and noises. Then, a dynamic template update strategy is designed to avoid tracking failures brought about by wrong matching or occlusion. Finally, the system synthesizes the least square integrated predictor, realizing tracking online in complex circumstances. The results of ground experiments show that the proposed algorithm can decrease the need for sophisticated computation and improves matching accuracy. PMID:26703609

  13. Original GaN-based LED structure on ZnO template by MOCVD

    NASA Astrophysics Data System (ADS)

    Lin, Ray-Ming; Yu, Sheng-Fu; Chen, Miin-Jang; Hsu, Wen-Ching

    2010-03-01

    In this study, we have successfully grown blue LED structure on ZnO template (deposited on sapphire substrate by atomic layer deposition, ALD) by atmospheric pressure metal-organic chemical vapor deposition (AP-MOCVD). Although GaN semiconductor material is very similar to ZnO in many ways, i.e. relatively small lattice mismatch ~1.8 % compared with traditional sapphire substrate~16 %, it still has a big challenge when GaN-based LEDs grow on ZnO template at usually growth temperature near 1100°C. With too high a temperature and a long deposited time, it would cause reaction at GaN/ZnO interface which is a vital reason that degrades the GaN crystalline quality. In view of this, we introduced an optimized thin AlN cover layer on ZnO template protecting the underneath ZnO layer and then obtained a real work LED structure. Meanwhile, the TEM measurement characterized the epilayer crystalline structure. The optical properties also were carried out by photoluminescence and electroluminescence analysis. Finally, with a suitable fabrication of LED processing, the ZnO template may has the potential as a sacrificial layer by chemical etching technical instead of conventional laser lifted-off.

  14. A TSR Visual Servoing System Based on a Novel Dynamic Template Matching Method.

    PubMed

    Cai, Jia; Huang, Panfeng; Zhang, Bin; Wang, Dongke

    2015-12-21

    The so-called Tethered Space Robot (TSR) is a novel active space debris removal system. To solve its problem of non-cooperative target recognition during short-distance rendezvous events, this paper presents a framework for a real-time visual servoing system using non-calibrated monocular-CMOS (Complementary Metal Oxide Semiconductor). When a small template is used for matching with a large scene, it always leads to mismatches, so a novel template matching algorithm to solve the problem is presented. Firstly, the novel matching algorithm uses a hollow annulus structure according to a FAST (Features from Accelerated Segment) algorithm and makes the method be rotation-invariant. Furthermore, the accumulative deviation can be decreased by the hollow structure. The matching function is composed of grey and gradient differences between template and object image, which help it reduce the effects of illumination and noises. Then, a dynamic template update strategy is designed to avoid tracking failures brought about by wrong matching or occlusion. Finally, the system synthesizes the least square integrated predictor, realizing tracking online in complex circumstances. The results of ground experiments show that the proposed algorithm can decrease the need for sophisticated computation and improves matching accuracy.

  15. Self-assembled DNA nanostructures and DNA-templated silver nanowires

    NASA Astrophysics Data System (ADS)

    Park, Sung Ha

    DNA-based nanotechnology has been attractive as a novel assembly method for fabricating nanostructures for the last two decades. Artificially designed, self-assembled DNA nanostructures have been reported with various geometrical structures and functionalities: one- and two-dimensional periodically patterned structures, three-dimensional polyhedra, nanomechanical devices, molecular computers, and organization of other functionalized molecules. This thesis describes self-assembled DNA nanostructures and DNA-templated metallic nanowires. One- and two-dimensional periodically patterned superstructures, such as filaments, lattices, nanoribbons, nanotracks, and nanogrids, utilizing newly conceived two distinct DNA motifs---three helix bundles, and the cross-tiles as well as synthetic double-stranded DNA molecules---will be discussed with unique design schemes and characteristics. DNA complexes have been visualized by high-resolution tapping mode atomic force microscopy under buffer. Their dimensions are shown to be in excellent agreement with designed structures. We have also presented fabrication of size-controllable, fully addressable, and precisely programmable DNA-based nanomatrices, consisting of two different cross-tiles using a novel stepwise assembly technique. Especially in design and construction of functionalized electronic nanodevices, properly fabricated DNA lattices can serve as a precisely controllable and programmable scaffold for organizing functionalized nanomaterials. DNA-templated metallic nanowires are an example demonstration of DNA molecules' scaffold capability and have been considered an interesting research subject for the last decade. Until recently, mostly native lambda-DNA molecules have been used as template for fabricating various metallic nanowires, such as silver, gold, palladium, platinum, and copper. In this thesis, we also present fabrication of metallic silver nanowires templated on artificially designed one-dimensional DNA

  16. Process for the preparation of metal-containing nanostructured films

    NASA Technical Reports Server (NTRS)

    Lu, Yunfeng (Inventor); Wang, Donghai (Inventor)

    2006-01-01

    Metal-containing nanostructured films are prepared by electrodepositing a metal-containing composition within the pores of a mesoporous silica template to form a metal-containing silica nanocomposite. The nanocomposite is annealed to strengthen the deposited metal-containing composition. The silica is then removed from the nanocomposite, e.g., by dissolving the silica in an etching solution to provide a self-supporting metal-containing nanostructured film. The nanostructured films have a nanowire or nanomesh architecture depending on the pore structure of the mesoporous silica template used to prepare the films.

  17. Physical synthesis of quantum circuits using templates

    NASA Astrophysics Data System (ADS)

    Mirkhani, Zahra; Mohammadzadeh, Naser

    2016-06-01

    Similar to traditional CMOS circuits, quantum circuit design flow is divided into two main processes: logic synthesis and physical design. Addressing the limitations imposed on optimization of the quantum circuit metrics because of no information sharing between logic synthesis and physical design processes, the concept of "physical synthesis" was introduced for quantum circuit flow, and a few techniques were proposed for it. Following that concept, in this paper a new approach for physical synthesis inspired by template matching idea in quantum logic synthesis is proposed to improve the latency of quantum circuits. Experiments show that by using template matching as a physical synthesis approach, the latency of quantum circuits can be improved by more than 23.55 % on average.

  18. Macroporous polymer foams by hydrocarbon templating

    PubMed Central

    Shastri, Venkatram Prasad; Martin, Ivan; Langer, Robert

    2000-01-01

    Porous polymeric media (polymer foams) are utilized in a wide range of applications, such as thermal and mechanical insulators, solid supports for catalysis, and medical devices. A process for the production of polymer foams has been developed. This process, which is applicable to a wide range of polymers, uses a hydrocarbon particulate phase as a template for the precipitation of the polymer phase and subsequent pore formation. The use of a hydrocarbon template allows for enhanced control over pore structure, porosity, and other structural and bulk characteristics of the polymer foam. Polymer foams with densities as low as 120 mg/cc, porosity as high as 87%, and high surface areas (20 m2/g) have been produced. Foams of poly(l-lactic acid), a biodegradable polymer, produced by this process have been used to engineer a variety of different structures, including tissues with complex geometries such as in the likeness of a human nose. PMID:10696111

  19. Physical synthesis of quantum circuits using templates

    NASA Astrophysics Data System (ADS)

    Mirkhani, Zahra; Mohammadzadeh, Naser

    2016-10-01

    Similar to traditional CMOS circuits, quantum circuit design flow is divided into two main processes: logic synthesis and physical design. Addressing the limitations imposed on optimization of the quantum circuit metrics because of no information sharing between logic synthesis and physical design processes, the concept of " physical synthesis" was introduced for quantum circuit flow, and a few techniques were proposed for it. Following that concept, in this paper a new approach for physical synthesis inspired by template matching idea in quantum logic synthesis is proposed to improve the latency of quantum circuits. Experiments show that by using template matching as a physical synthesis approach, the latency of quantum circuits can be improved by more than 23.55 % on average.

  20. A template for integrated community sustainability planning.

    PubMed

    Ling, Christopher; Hanna, Kevin; Dale, Ann

    2009-08-01

    This article describes a template for implementing an integrated community sustainability plan. The template emphasizes community engagement and outlines the components of a basic framework for integrating ecological, social and economic dynamics into a community plan. The framework is a series of steps that support a sustainable community development process. While it reflects the Canadian experience, the tools and techniques have applied value for a range of environmental planning contexts around the world. The research is case study based and draws from a diverse range of communities representing many types of infrastructure, demographics and ecological and geographical contexts. A critical path for moving local governments to sustainable community development is the creation and implementation of integrated planning approaches. To be effective and to be implemented, a requisite shift to sustainability requires active community engagement processes, political will, and a commitment to political and administrative accountability, and measurement. PMID:19495860

  1. Template analysis of a Faraday disk dynamo

    NASA Astrophysics Data System (ADS)

    Moroz, I. M.

    2008-12-01

    In a recent paper Moroz [1] returned to a nonlinear three-dimensional model of dynamo action for a self-exciting Faraday disk dynamo introduced by Hide et al. [2]. Since only two examples of chaotic behaviour were shown in [2], Moroz [1] performed a more extensive analysis of the dynamo model, producing a selection of bifurcation transition diagrams, including those encompassing the two examples of chaotic behaviour in [2]. Unstable periodic orbits were extracted and presented in [1], but no attempt was made to identify the underlying chaotic attractor. We rectify that here. Illustrating the procedure with one of the cases considered in [1], we use some of the unstable periodic orbits to identify a possible template for the chaotic attractor, using ideas from topology [3]. In particular, we investigate how the template is affected by changes in bifurcation parameter.

  2. Template-based synthesis of nickel oxide

    NASA Astrophysics Data System (ADS)

    Mironova-Ulmane, N.; Kuzmin, A.; Sildos, I.

    2015-03-01

    Nanocrystalline NiO has been produced using a facile template-based synthesis from nickel nitrate solutions using cellulose as a template. Thus obtained oxides were studied by scanning electron microscopy, x-ray diffraction, Raman scattering spectroscopy, photoluminescence spectroscopy and confocal spectromicroscopy. The filamentary/coral morphology of the samples has been evidenced and is built up of agglomerated nanocrystallites with a size in the range of about 26-36 nm. The presence of two-magnon contribution in Raman scattering spectra suggests the existence of antiferromagnetic ordering at room temperature. Finally, the observed near-infrared photoluminescence band at 850 nm has been tentatively attributed to the defect-perturbed Ni2+ states at the surface.

  3. Template-assisted synthesis and characterization of passivated nickel nanoparticles.

    PubMed

    Veena Gopalan, E; Malini, Ka; Santhoshkumar, G; Narayanan, Tn; Joy, Pa; Al-Omari, Ia; Sakthi Kumar, D; Yoshida, Yasuhiko; Anantharaman, Mr

    2010-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Nanoscale chemical templating of Si nanowires seeded with Al

    NASA Astrophysics Data System (ADS)

    Khayyat, Maha M.; Wacaser, Brent A.; Reuter, Mark C.; Ross, Frances M.; Sadana, Devendra K.; Chen, Tze-Chiang

    2013-06-01

    We describe a new approach for achieving controlled spatial placement of VLS-grown nanowires that uses an oxygen-reactive seed material and an oxygen-containing mask. Oxygen-reactive seed materials are of great interest for electronic applications, yet they cannot be patterned using the approaches developed for noble metal seed materials such as Au. This new process, nanoscale chemical templating, takes advantage of the reactivity of the blanket seed layer by depositing it over a patterned oxide that reacts with the seed material to prevent nanowire growth in undesired locations. Here we demonstrate this technique using Al as the seed material and SiO2 as the mask, and we propose that this methodology will be applicable to other reactive metals that are of interest for nanowire growth. The method has other advantages over conventional patterning approaches for certain applications including reducing patterning steps, flexibility in lithographic techniques, and high growth yields. We demonstrate its application with standard and microsphere lithography. We show a high growth yield and fidelity, with no NWs between openings and a majority of openings occupied by a single vertical nanowire, and discuss the dependence of yield on parameters.

  6. Patterning microsphere surfaces by templating colloidal crystals.

    PubMed

    Zhang, Gang; Wang, Dayang; Möhwald, Helmuth

    2005-01-01

    By using the upper single or double layers in colloidal crystals as masks during Au vapor deposition, various Au patterns have been successfully constructed on the surfaces of the lower spheres. The dimension and geometry of the Au patterns obtained are dependent on the orientation of the colloidal crystal templates. Our patterning procedure is independent of the curvature and chemical composition of the surfaces, which definitely pave a promising way to pattern highly curved surfaces.

  7. Deep Human Parsing with Active Template Regression.

    PubMed

    Liang, Xiaodan; Liu, Si; Shen, Xiaohui; Yang, Jianchao; Liu, Luoqi; Dong, Jian; Lin, Liang; Yan, Shuicheng

    2015-12-01

    In this work, the human parsing task, namely decomposing a human image into semantic fashion/body regions, is formulated as an active template regression (ATR) problem, where the normalized mask of each fashion/body item is expressed as the linear combination of the learned mask templates, and then morphed to a more precise mask with the active shape parameters, including position, scale and visibility of each semantic region. The mask template coefficients and the active shape parameters together can generate the human parsing results, and are thus called the structure outputs for human parsing. The deep Convolutional Neural Network (CNN) is utilized to build the end-to-end relation between the input human image and the structure outputs for human parsing. More specifically, the structure outputs are predicted by two separate networks. The first CNN network is with max-pooling, and designed to predict the template coefficients for each label mask, while the second CNN network is without max-pooling to preserve sensitivity to label mask position and accurately predict the active shape parameters. For a new image, the structure outputs of the two networks are fused to generate the probability of each label for each pixel, and super-pixel smoothing is finally used to refine the human parsing result. Comprehensive evaluations on a large dataset well demonstrate the significant superiority of the ATR framework over other state-of-the-arts for human parsing. In particular, the F1-score reaches 64.38 percent by our ATR framework, significantly higher than 44.76 percent based on the state-of-the-art algorithm [28]. PMID:26539846

  8. Deep Human Parsing with Active Template Regression.

    PubMed

    Liang, Xiaodan; Liu, Si; Shen, Xiaohui; Yang, Jianchao; Liu, Luoqi; Dong, Jian; Lin, Liang; Yan, Shuicheng

    2015-12-01

    In this work, the human parsing task, namely decomposing a human image into semantic fashion/body regions, is formulated as an active template regression (ATR) problem, where the normalized mask of each fashion/body item is expressed as the linear combination of the learned mask templates, and then morphed to a more precise mask with the active shape parameters, including position, scale and visibility of each semantic region. The mask template coefficients and the active shape parameters together can generate the human parsing results, and are thus called the structure outputs for human parsing. The deep Convolutional Neural Network (CNN) is utilized to build the end-to-end relation between the input human image and the structure outputs for human parsing. More specifically, the structure outputs are predicted by two separate networks. The first CNN network is with max-pooling, and designed to predict the template coefficients for each label mask, while the second CNN network is without max-pooling to preserve sensitivity to label mask position and accurately predict the active shape parameters. For a new image, the structure outputs of the two networks are fused to generate the probability of each label for each pixel, and super-pixel smoothing is finally used to refine the human parsing result. Comprehensive evaluations on a large dataset well demonstrate the significant superiority of the ATR framework over other state-of-the-arts for human parsing. In particular, the F1-score reaches 64.38 percent by our ATR framework, significantly higher than 44.76 percent based on the state-of-the-art algorithm [28].

  9. CLIPS template system for program understanding

    NASA Technical Reports Server (NTRS)

    Finkbine, Ronald B.

    1994-01-01

    Program understanding is a subfield of software reengineering and attempts to recognize the run-time behavior of source code. To this point, success in this area has been limited to very small code segments. An expert system, HLAR (High-Level Algorithm Recognizer), has been written in CLIPS and recognizes three sorting algorithms, selection sort, quicksort, and heapsort. This paper describes the HLAR system in general and, in depth, the CLIPS templates used for program representation and understanding.

  10. Human action recognition using motion energy template

    NASA Astrophysics Data System (ADS)

    Shao, Yanhua; Guo, Yongcai; Gao, Chao

    2015-06-01

    Human action recognition is an active and interesting research topic in computer vision and pattern recognition field that is widely used in the real world. We proposed an approach for human activity analysis based on motion energy template (MET), a new high-level representation of video. The main idea for the MET model is that human actions could be expressed as the composition of motion energy acquired in a three-dimensional (3-D) space-time volume by using a filter bank. The motion energies were directly computed from raw video sequences, thus some problems, such as object location and segmentation, etc., are definitely avoided. Another important competitive merit of this MET method is its insensitivity to gender, hair, and clothing. We extract MET features by using the Bhattacharyya coefficient to measure the motion energy similarity between the action template video and the tested video, and then the 3-D max-pooling. Using these features as input to the support vector machine, extensive experiments on two benchmark datasets, Weizmann and KTH, were carried out. Compared with other state-of-the-art approaches, such as variation energy image, dynamic templates and local motion pattern descriptors, the experimental results demonstrate that our MET model is competitive and promising.

  11. PROTEIN TEMPLATES IN HARD TISSUE ENGINEERING

    PubMed Central

    George, Anne; Ravindran, Sriram

    2010-01-01

    Biomineralization processes such as formation of bones and teeth require controlled mineral deposition and self-assembly into hierarchical biocomposites with unique mechanical properties. Ideal biomaterials for regeneration and repair of hard tissues must be biocompatible, possess micro and macroporosity for vascular invasion, provide surface chemistry and texture that facilitate cell attachment, proliferation, differentiation of lineage specific progenitor cells, and induce deposition of calcium phosphate mineral. To expect in-vivo like cellular response several investigators have used extracellular matrix proteins as templates to recreate in-vivo microenvironment for regeneration of hard tissues. Recently, several novel methods of designing tissue repair and restoration materials using bioinspired strategies are currently being formulated. Nanoscale structured materials can be fabricated via the spontaneous organization of self-assembling proteins to construct hierarchically organized nanomaterials. The advantage of such a method is that polypeptides can be specifically designed as building blocks incorporated with molecular recognition features and spatially distributed bioactive ligands that would provide a physiological environment for cells in-vitro and in-vivo. This is a rapidly evolving area and provides a promising platform for future development of nanostructured templates for hard tissue engineering. In this review we try to highlight the importance of proteins as templates for regeneration and repair of hard tissues as well as the potential of peptide based nanomaterials for regenerative therapies. PMID:20802848

  12. Sacrificial template method of fabricating a nanotube

    DOEpatents

    Yang, Peidong; He, Rongrui; Goldberger, Joshua; Fan, Rong; Wu, Yi-Ying; Li, Deyu; Majumdar, Arun

    2007-05-01

    Methods of fabricating uniform nanotubes are described in which nanotubes were synthesized as sheaths over nanowire templates, such as using a chemical vapor deposition process. For example, single-crystalline zinc oxide (ZnO) nanowires are utilized as templates over which gallium nitride (GaN) is epitaxially grown. The ZnO templates are then removed, such as by thermal reduction and evaporation. The completed single-crystalline GaN nanotubes preferably have inner diameters ranging from 30 nm to 200 nm, and wall thicknesses between 5 and 50 nm. Transmission electron microscopy studies show that the resultant nanotubes are single-crystalline with a wurtzite structure, and are oriented along the <001> direction. The present invention exemplifies single-crystalline nanotubes of materials with a non-layered crystal structure. Similar "epitaxial-casting" approaches could be used to produce arrays and single-crystalline nanotubes of other solid materials and semiconductors. Furthermore, the fabrication of multi-sheath nanotubes are described as well as nanotubes having multiple longitudinal segments.

  13. DNA-templated gold nanoparticles formation.

    PubMed

    Sun, Lanlan; Song, Yonghai; Wang, Li; Sun, Yujing; Guo, Cunlan; Liu, Zhelin; Li, Zhuang

    2008-09-01

    The interaction between HAuCl4 and DNA has enabled creation of DNA-templated gold nanoparticles without formation of large nanoparticles. It was found that spheral DNA-HAuCl4 hybrid of 8.7 nm in diameter, flower-like DNA-HAuCl4 hybrid, nanoparticles chains and nanoparticles network of DNA-HAuCl4 hybrid could be obtained by varying the reaction conditions, including DNA concentration and reaction temperature. The intermediate product was investigated by shortening the reaction time of DNA and HAuCl4, and the obtained nanoparticles preserved a small DNA segment, which indicated that the reaction between DNA and HAuCl4 had a process. The addition of reduction reagent resulted in DNA-templated gold nanoparticles and nanoflowers, respectively. UV-vis absorption spectra were used to characterize the DNA-HAuCl4 hybrid and the gold nanostructures templated on DNA, and XPS spectra were used to compare the composition of DNA-Au(III) complex and gold nanoparticles. AFM and TEM results revealed that the spheral gold nanoparticles of about 11 nm in size and flower-like gold nanoparticles were formed after the addition of NaBH4.

  14. Epitaxial growth a-plane ZnO films on a-GaN/r-Al2O3 templates

    NASA Astrophysics Data System (ADS)

    Liu, Cheng; Dai, Jiangnan; Wu, Zhihao; Han, Xiangyun; He, Qinghua; Yu, Chenhui; Zhang, Lei; Gao, Yihua; Chen, Changqing

    2008-12-01

    In this work, we have grown a-plane ZnO films on a-plane GaN/r-sapphire templates by pulsed laser deposition. The aplane GaN of the templates is aimed to mitigate the large lattice mismatch between ZnO and sapphire, and was grown by metal organic chemical vapor deposition. The grown a-plane ZnO films have been analyzed by various techniques such as high resolution X-ray diffraction, photoluminescence. It shows that high quality a-plane ZnO films have been achieved by our growth method.

  15. A Robust and Engineerable Self-Assembling Protein Template for the Synthesis and Patterning of Ordered Nanoparticle Arrays

    NASA Technical Reports Server (NTRS)

    McMillan, R. Andrew; Howard, Jeanie; Zaluzec, Nestor J.; Kagawa, Hiromi K.; Li, Yi-Fen; Paavola, Chad D.; Trent, Jonathan D.

    2004-01-01

    Self-assembling biomolecules that form highly ordered structures have attracted interest as potential alternatives to conventional lithographic processes for patterning materials. Here we introduce a general technique for patterning materials on the nanoscale using genetically modified protein cage structures called chaperonins that self-assemble into crystalline templates. Constrained chemical synthesis of transition metal nanoparticles is specific to templates genetically functionalized with poly-Histidine sequences. These arrays of materials are ordered by the nanoscale structure of the crystallized protein. This system may be easily adapted to pattern a variety of materials given the rapidly growing list of peptide sequences selected by screening for specificity for inorganic materials.

  16. Development of Total Knee Replacement Digital Templating Software

    NASA Astrophysics Data System (ADS)

    Yusof, Siti Fairuz; Sulaiman, Riza; Thian Seng, Lee; Mohd. Kassim, Abdul Yazid; Abdullah, Suhail; Yusof, Shahril; Omar, Masbah; Abdul Hamid, Hamzaini

    In this study, by taking full advantage of digital X-ray and computer technology, we have developed a semi-automated procedure to template knee implants, by making use of digital templating method. Using this approach, a software system called OrthoKneeTMhas been designed and developed. The system is to be utilities as a study in the Department of Orthopaedic and Traumatology in medical faculty, UKM (FPUKM). OrthoKneeTMtemplating process employs uses a technique similar to those used by many surgeons, using acetate templates over X-ray films. Using template technique makes it easy to template various implant from every Implant manufacturers who have with a comprehensive database of templates. The templating functionality includes, template (knee) and manufactures templates (Smith & Nephew; and Zimmer). From an image of patient x-ray OrthoKneeTMtemplates help in quickly and easily reads to the approximate template size needed. The visual templating features then allow us quickly review multiple template sizes against the X-ray and thus obtain the nearly precise view of the implant size required. The system can assist by templating on one patient image and will generate reports that can accompany patient notes. The software system was implemented in Visual basic 6.0 Pro using the object-oriented techniques to manage the graphics and objects. The approaches for image scaling will be discussed. Several of measurement in orthopedic diagnosis process have been studied and added in this software as measurement tools features using mathematic theorem and equations. The study compared the results of the semi-automated (using digital templating) method to the conventional method to demonstrate the accuracy of the system.

  17. Anisotropic metal growth on phospholipid nanodiscs via lipid bilayer expansion

    NASA Astrophysics Data System (ADS)

    Oertel, Jana; Keller, Adrian; Prinz, Julia; Schreiber, Benjamin; Hübner, René; Kerbusch, Jochen; Bald, Ilko; Fahmy, Karim

    2016-05-01

    Self-assembling biomolecules provide attractive templates for the preparation of metallic nanostructures. However, the intuitive transfer of the “outer shape” of the assembled macromolecules to the final metallic particle depends on the intermolecular forces among the biomolecules which compete with interactions between template molecules and the metal during metallization. The shape of the bio-template may thus be more dynamic than generally assumed. Here, we have studied the metallization of phospholipid nanodiscs which are discoidal particles of ~10 nm diameter containing a lipid bilayer ~5 nm thick. Using negatively charged lipids, electrostatic adsorption of amine-coated Au nanoparticles was achieved and followed by electroless gold deposition. Whereas Au nanoparticle adsorption preserves the shape of the bio-template, metallization proceeds via invasion of Au into the hydrophobic core of the nanodisc. Thereby, the lipidic phase induces a lateral growth that increases the diameter but not the original thickness of the template. Infrared spectroscopy reveals lipid expansion and suggests the existence of internal gaps in the metallized nanodiscs, which is confirmed by surface-enhanced Raman scattering from the encapsulated lipids. Interference of metallic growth with non-covalent interactions can thus become itself a shape-determining factor in the metallization of particularly soft and structurally anisotropic biomaterials.

  18. Anisotropic metal growth on phospholipid nanodiscs via lipid bilayer expansion

    PubMed Central

    Oertel, Jana; Keller, Adrian; Prinz, Julia; Schreiber, Benjamin; Hübner, René; Kerbusch, Jochen; Bald, Ilko; Fahmy, Karim

    2016-01-01

    Self-assembling biomolecules provide attractive templates for the preparation of metallic nanostructures. However, the intuitive transfer of the “outer shape” of the assembled macromolecules to the final metallic particle depends on the intermolecular forces among the biomolecules which compete with interactions between template molecules and the metal during metallization. The shape of the bio-template may thus be more dynamic than generally assumed. Here, we have studied the metallization of phospholipid nanodiscs which are discoidal particles of ~10 nm diameter containing a lipid bilayer ~5 nm thick. Using negatively charged lipids, electrostatic adsorption of amine-coated Au nanoparticles was achieved and followed by electroless gold deposition. Whereas Au nanoparticle adsorption preserves the shape of the bio-template, metallization proceeds via invasion of Au into the hydrophobic core of the nanodisc. Thereby, the lipidic phase induces a lateral growth that increases the diameter but not the original thickness of the template. Infrared spectroscopy reveals lipid expansion and suggests the existence of internal gaps in the metallized nanodiscs, which is confirmed by surface-enhanced Raman scattering from the encapsulated lipids. Interference of metallic growth with non-covalent interactions can thus become itself a shape-determining factor in the metallization of particularly soft and structurally anisotropic biomaterials. PMID:27216789

  19. Anisotropic metal growth on phospholipid nanodiscs via lipid bilayer expansion.

    PubMed

    Oertel, Jana; Keller, Adrian; Prinz, Julia; Schreiber, Benjamin; Hübner, René; Kerbusch, Jochen; Bald, Ilko; Fahmy, Karim

    2016-01-01

    Self-assembling biomolecules provide attractive templates for the preparation of metallic nanostructures. However, the intuitive transfer of the "outer shape" of the assembled macromolecules to the final metallic particle depends on the intermolecular forces among the biomolecules which compete with interactions between template molecules and the metal during metallization. The shape of the bio-template may thus be more dynamic than generally assumed. Here, we have studied the metallization of phospholipid nanodiscs which are discoidal particles of ~10 nm diameter containing a lipid bilayer ~5 nm thick. Using negatively charged lipids, electrostatic adsorption of amine-coated Au nanoparticles was achieved and followed by electroless gold deposition. Whereas Au nanoparticle adsorption preserves the shape of the bio-template, metallization proceeds via invasion of Au into the hydrophobic core of the nanodisc. Thereby, the lipidic phase induces a lateral growth that increases the diameter but not the original thickness of the template. Infrared spectroscopy reveals lipid expansion and suggests the existence of internal gaps in the metallized nanodiscs, which is confirmed by surface-enhanced Raman scattering from the encapsulated lipids. Interference of metallic growth with non-covalent interactions can thus become itself a shape-determining factor in the metallization of particularly soft and structurally anisotropic biomaterials. PMID:27216789

  20. Shape-Controlled Metal-Metal and Metal-Polymer Janus Structures by Thermoplastic Embossing.

    PubMed

    Hasan, Molla; Kahler, Niloofar; Kumar, Golden

    2016-05-01

    We report the fabrication of metal-metal and metal-polymer Janus structures by embossing of thermoplastic metallic glasses and polymers. Hybrid structures with controllable shapes and interfaces are synthesized by template-assisted embossing. Different manufacturing strategies such as co-embossing and additive embossing are demonstrated for joining the materials with diverse compositions and functionalities. Structures with distinct combinations of properties such as hydrophobic-hydrophilic, opaque-transparent, insulator-conductor, and nonmagnetic-ferromagnetic are produced using this approach. These anisotropic properties are further utilized for selective functionalization of Janus structures.

  1. Fabrication of submicron metallic grids with interference and phase-mask holography

    SciTech Connect

    Park, Joong-Mok; Kim, Tae-Geun; Constant, Kristen; Ho, Kai-Ming

    2011-01-25

    Complex, submicron Cu metallic mesh nanostructures are made by electrochemical deposition using polymer templates made from photoresist. The polymer templates are fabricated with photoresist using two-beam interference holography and phase mask holography with three diffracted beams. Freestanding metallic mesh structures are made in two separate electrodepositions with perpendicular photoresist grating templates. Cu mesh square nanostructures having large (52.6%) open areas are also made by single electrodeposition with a photoresist template made with a phase mask. These structures have potential as electrodes in photonic devices.

  2. Self-assembled SnO2 micro- and nanosphere-based gas sensor thick films from an alkoxide-derived high purity aqueous colloid precursor.

    PubMed

    Kelp, G; Tätte, T; Pikker, S; Mändar, H; Rozhin, A G; Rauwel, P; Vanetsev, A S; Gerst, A; Merisalu, M; Mäeorg, U; Natali, M; Persson, I; Kessler, V G

    2016-04-01

    Tin oxide is considered to be one of the most promising semiconductor oxide materials for use as a gas sensor. However, a simple route for the controllable build-up of nanostructured, sufficiently pure and hierarchical SnO2 structures for gas sensor applications is still a challenge. In the current work, an aqueous SnO2 nanoparticulate precursor sol, which is free of organic contaminants and sorbed ions and is fully stable over time, was prepared in a highly reproducible manner from an alkoxide Sn(OR)4 just by mixing it with a large excess of pure neutral water. The precursor is formed as a separate liquid phase. The structure and purity of the precursor is revealed using XRD, SAXS, EXAFS, HRTEM imaging, FTIR, and XRF analysis. An unconventional approach for the estimation of the particle size based on the quantification of the Sn-Sn contacts in the structure was developed using EXAFS spectroscopy and verified using HRTEM. To construct sensors with a hierarchical 3D structure, we employed an unusual emulsification technique not involving any additives or surfactants, using simply the extraction of the liquid phase, water, with the help of dry butanol under ambient conditions. The originally generated crystalline but yet highly reactive nanoparticles form relatively uniform spheres through self-assembly and solidify instantly. The spheres floating in butanol were left to deposit on the surface of quartz plates bearing sputtered gold electrodes, producing ready-for-use gas sensors in the form of ca. 50 μm thick sphere-based-films. The films were dried for 24 h and calcined at 300 °C in air before use. The gas sensitivity of the structures was tested in the temperature range of 150-400 °C. The materials showed a very quickly emerging and reversible (20-30 times) increase in electrical conductivity as a response to exposure to air containing 100 ppm of H2 or CO and short (10 s) recovery times when the gas flow was stopped. PMID:26960813

  3. DNA repair by RNA: Templated, or not templated, that is the question.

    PubMed

    Meers, Chance; Keskin, Havva; Storici, Francesca

    2016-08-01

    Cells are continuously exposed to both endogenous and exogenous sources of genomic stress. To maintain chromosome stability, a variety of mechanisms have evolved to cope with the multitude of genetic abnormalities that can arise over the life of a cell. Still, failures to repair these lesions are the driving force of cancers and other degenerative disorders. DNA double-strand breaks (DSBs) are among the most toxic genetic lesions, inhibiting cell ability to replicate, and are sites of mutations and chromosomal rearrangements. DSB repair is known to proceed via two major mechanisms: homologous recombination (HR) and non-homologous end joining (NHEJ). HR reliance on the exchange of genetic information between two identical or nearly identical DNA molecules offers increased accuracy. While the preferred substrate for HR in mitotic cells is the sister chromatid, this is limited to the S and G2 phases of the cell cycle. However, abundant amounts of homologous genetic substrate may exist throughout the cell cycle in the form of RNA. Considered an uncommon occurrence, the direct transfer of information from RNA to DNA is thought to be limited to special circumstances. Studies have shown that RNA molecules reverse transcribed into cDNA can be incorporated into DNA at DSB sites via a non-templated mechanism by NHEJ or a templated mechanism by HR. In addition, synthetic RNA molecules can directly template the repair of DSBs in yeast and human cells via an HR mechanism. New work suggests that even endogenous transcript RNA can serve as a homologous template to repair a DSB in chromosomal DNA. In this perspective, we will review and discuss the recent advancements in DSB repair by RNA via non-templated and templated mechanisms. We will provide current findings, models and future challenges investigating RNA and its role in DSB repair. PMID:27237587

  4. Fabrication of high fidelity, high index three-dimensional photonic crystals using a templating approach

    NASA Astrophysics Data System (ADS)

    Xu, Yongan

    , a highly thermal and mechanical stable template is desired for PC fabrication. We fabricate the 3D POSS structures by MBIL, which can be converted to crack-free silica-like templates over the entire sample area (˜5 mm in diameter) by either thermal treatment in Ar at 500°C or O2 plasma, and the porosity can be conveniently controlled by O2 plasma power and time. Since POSS derivatives are soluble in HF aqueous solutions, we successfully replicate the 3D porous structures into polymers, such as PGMA and poly(dimethyl siloxane) (PDMS). We note that all the fabrication processes are conducted at room temperature, including template fabrication, infiltration and removal. Further, using 3D POSS structures as templates, here, we demonstrate the synthesis of 3D photonic crystals from silicon carbide and boron carbide, respectively, which are thermally stable above 1100°C in Ar. These non-oxide ceramic photonic crystals are potentially useful as ultrahigh temperature thermal barrier coatings that provide thermal protection for metallic components.

  5. Tuning the composition and nanostructure of Pt/Ir films via anodized aluminum oxide templated atomic layer deposition.

    SciTech Connect

    Comstock, D. J.; Christensen, S. T.; Elam, J. W.; Pellin, M. J.; Hersam, M. C.; Northwestern Univ.

    2010-09-23

    Nanostructured metal films have been widely studied for their roles in sensing, catalysis, and energy storage. In this work, the synthesis of compositionally controlled and nanostructured Pt/Ir films by atomic layer deposition (ALD) into porous anodized aluminum oxide templates is demonstrated. Templated ALD provides advantages over alternative synthesis techniques, including improved film uniformity and conformality as well as atomic-scale control over morphology and composition. Nanostructured Pt ALD films are demonstrated with morphological control provided by the Pt precursor exposure time and the number of ALD cycles. With these approaches, Pt films with enhanced surface areas, as characterized by roughness factors as large as 310, are reproducibly synthesized. Additionally, nanostructured Ptlr alloy films of controlled composition and morphology are demonstrated by templated ALD, with compositions varying systematically from pure Pt to pure Ir. Lastly, the application of nanostructured Pt films to electrochemical sensing applications is demonstrated by the non-enzymatic sensing of glucose.

  6. Electrical and structural properties of ZnO synthesized via infiltration of lithographically defined polymer templates

    SciTech Connect

    Nam, Chang-Yong Stein, Aaron; Kisslinger, Kim; Black, Charles T.

    2015-11-16

    We investigate the electrical and structural properties of infiltration-synthesized ZnO. In-plane ZnO nanowire arrays with prescribed positional registrations are generated by infiltrating diethlyzinc and water vapor into lithographically defined SU-8 polymer templates and removing organic matrix by oxygen plasma ashing. Transmission electron microscopy reveals that homogeneously amorphous as-infiltrated polymer templates transform into highly nanocrystalline ZnO upon removal of organic matrix. Field-effect transistor device measurements show that the synthesized ZnO after thermal annealing displays a typical n-type behavior, ∼10{sup 19 }cm{sup −3} carrier density, and ∼0.1 cm{sup 2} V{sup −1} s{sup −1} electron mobility, reflecting highly nanocrystalline internal structure. The results demonstrate the potential application of infiltration synthesis in fabricating metal oxide electronic devices.

  7. Unidirectional Lasing from Template-Stripped Two-Dimensional Plasmonic Crystals.

    PubMed

    Yang, Ankun; Li, Zhongyang; Knudson, Michael P; Hryn, Alexander J; Wang, Weijia; Aydin, Koray; Odom, Teri W

    2015-12-22

    Plasmon lasers support cavity structures with sizes below that of the diffraction limit. However, most plasmon-based lasers show bidirectional lasing emission or emission with limited far-field directionality and large radiative losses. Here, we report unidirectional lasing from ultrasmooth, template-stripped two-dimensional (2D) plasmonic crystals. Optically pumped 2D plasmonic crystals (Au or Ag) surrounded by dye molecules exhibited lasing in a single emission direction and their lasing wavelength could be tuned by modulating the dielectric environment. We found that 2D plasmonic crystals were an ideal architecture to screen how nanocavity unit-cell structure, metal material, and gain media affected the lasing response. We discovered that template-stripped strong plasmonic materials with cylindrical posts were an optimal cavity design for a unidirectional laser operating at room temperature. PMID:26456299

  8. Electrical and structural properties of ZnO synthesized via infiltration of lithographically defined polymer templates

    DOE PAGES

    Chang-Yong Nam; Stein, Aaron; Kisslinger, Kim; Black, Charles T.

    2015-11-17

    We investigate the electrical and structural properties of infiltration-synthesized ZnO. In-plane ZnO nanowire arrays with prescribed positional registrations are generated by infiltrating diethlyzinc and water vapor into lithographically defined SU-8 polymer templates and removing organic matrix by oxygen plasma ashing. Transmission electron microscopy reveals that homogeneously amorphous as-infiltrated polymer templates transform into highly nanocrystalline ZnO upon removal of organic matrix. Field-effect transistor device measurements show that the synthesized ZnO after thermal annealing displays a typical n-type behavior, ~1019 cm-3 carrier density, and ~0.1 cm2 V-1 s-1 electron mobility, reflecting highly nanocrystalline internal structure. The results demonstrate the potential application ofmore » infiltration synthesis in fabricating metal oxide electronic devices.« less

  9. Electrical and structural properties of ZnO synthesized via infiltration of lithographically defined polymer templates

    SciTech Connect

    Chang-Yong Nam; Stein, Aaron; Kisslinger, Kim; Black, Charles T.

    2015-11-17

    We investigate the electrical and structural properties of infiltration-synthesized ZnO. In-plane ZnO nanowire arrays with prescribed positional registrations are generated by infiltrating diethlyzinc and water vapor into lithographically defined SU-8 polymer templates and removing organic matrix by oxygen plasma ashing. Transmission electron microscopy reveals that homogeneously amorphous as-infiltrated polymer templates transform into highly nanocrystalline ZnO upon removal of organic matrix. Field-effect transistor device measurements show that the synthesized ZnO after thermal annealing displays a typical n-type behavior, ~1019 cm-3 carrier density, and ~0.1 cm2 V-1 s-1 electron mobility, reflecting highly nanocrystalline internal structure. The results demonstrate the potential application of infiltration synthesis in fabricating metal oxide electronic devices.

  10. Pulsed electrodeposition into AAO templates for CVD growth of carbon nanotube arrays

    NASA Astrophysics Data System (ADS)

    Sklar, G. P.; Paramguru, K.; Misra, M.; La Combe, J. C.

    2005-08-01

    Anodic aluminium oxide (AAO) templates for multi-walled carbon nanotube (MWCNT) growth were produced by anodization of aluminium followed by pulse-reverse electrodeposition of cobalt inside the AAO pores. Cobalt functioned as the catalyst for H2/C2H2 chemical vapour deposition (CVD) growth of fairly well graphitized MWCNTs initiating inside the majority of the AAO pores and quickly growing beyond the pore confines. A technique is introduced for the production of AAO templates that fill evenly during pulsed electrodeposition. The electrodeposition produced an active metallic catalyst in the pore bottoms, with minimal over-filling. This process also eliminates the reduction step necessary when alternating current (AC) electrodeposition is used for filling AAO pores.

  11. Template-directed fabrication of porous gas diffusion layer for magnesium air batteries

    NASA Astrophysics Data System (ADS)

    Xue, Yejian; Miao, He; Sun, Shanshan; Wang, Qin; Li, Shihua; Liu, Zhaoping

    2015-11-01

    The uniform micropore distribution in the gas diffusion layers (GDLs) of the air-breathing cathode is very important for the metal air batteries. In this work, the super-hydrophobic GDL with the interconnected regular pores is prepared by a facile silica template method, and then the electrochemical properties of the Mg air batteries containing these GDLs are investigated. The results indicate that the interconnected and uniform pore structure, the available water-breakout pressure and the high gas permeability coefficient of the GDL can be obtained by the application of 30% silica template. The maximum power density of the Mg air battery containing the GDL with 30% regular pores reaches 88.9 mW cm-2 which is about 1.2 times that containing the pristine GDL. Furthermore, the GDL with 30% regular pores exhibits the improved the long term hydrophobic stability.

  12. Unidirectional Lasing from Template-Stripped Two-Dimensional Plasmonic Crystals.

    PubMed

    Yang, Ankun; Li, Zhongyang; Knudson, Michael P; Hryn, Alexander J; Wang, Weijia; Aydin, Koray; Odom, Teri W

    2015-12-22

    Plasmon lasers support cavity structures with sizes below that of the diffraction limit. However, most plasmon-based lasers show bidirectional lasing emission or emission with limited far-field directionality and large radiative losses. Here, we report unidirectional lasing from ultrasmooth, template-stripped two-dimensional (2D) plasmonic crystals. Optically pumped 2D plasmonic crystals (Au or Ag) surrounded by dye molecules exhibited lasing in a single emission direction and their lasing wavelength could be tuned by modulating the dielectric environment. We found that 2D plasmonic crystals were an ideal architecture to screen how nanocavity unit-cell structure, metal material, and gain media affected the lasing response. We discovered that template-stripped strong plasmonic materials with cylindrical posts were an optimal cavity design for a unidirectional laser operating at room temperature.

  13. Template polymerization synthesis of hydrogel and silica composite for sorption of some rare earth elements.

    PubMed

    Borai, E H; Hamed, M G; El-kamash, A M; Siyam, T; El-Sayed, G O

    2015-10-15

    New sorbents containing 2-acrylamido 2-methyl propane sulphonic acid monomer onto poly(vinyl pyrilidone) P(VP-AMPS) hydrogel and P(VP-AMPS-SiO2) composite have been synthesized by radiation template polymerization. The effect of absorbed dose rate (kGy), crosslinker concentration and polymer/monomer ratio on the degree of template polymerization of P(VP-AMPS) hydrogel was studied. The degree of polymerization was evaluated by the calculated percent conversion and swelling degree. The maximum capacity of P(VP-AMPS) hydrogel toward Cu(+2) metal ion found to be 91 mg/gm. The polymeric composite P(VP-AMPS-SiO2) has been successfully synthesized. The structure of the prepared hydrogel and composite were confirmed by FTIR, thermal analysis (TGA and DTA) and SEM micrograph. Batch adsorption studies for La(3+), Ce(3+), Nd(3+), Eu(3+) and Pb(+2) metal ions on the prepared hydrogel and composite were investigated as a function of shaking time, pH and metal ion concentration. The sorption efficiency of the prepared hydrogel and composite toward light rare earth elements (LREEs) are arranged in the order La(3+)>Ce(3+)>Nd(3+)>Eu(3+). The obtained results demonstrated the superior adsorption capacity of the composite over the polymeric hydrogel. The maximum capacity of the polymeric composite was found to be 116, 103, 92, 76, 74 mg/gm for La(3+), Ce(3+), Nd(3+), Eu(3+) and Pb(2+) metal ions respectively.

  14. Engineering DNA self-assemblies as templates for functional nanostructures.

    PubMed

    Wang, Zhen-Gang; Ding, Baoquan

    2014-06-17

    CONSPECTUS: DNA is a well-known natural molecule that carries genetic information. In recent decades, DNA has been used beyond its genetic role as a building block for the construction of engineering materials. Many strategies, such as tile assembly, scaffolded origami and DNA bricks, have been developed to design and produce 1D, 2D, and 3D architectures with sophisticated morphologies. Moreover, the spatial addressability of DNA nanostructures and sequence-dependent recognition enable functional elements to be precisely positioned and allow for the control of chemical and biochemical processes. The spatial arrangement of heterogeneous components using DNA nanostructures as the templates will aid in the fabrication of functional materials that are difficult to produce using other methods and can address scientific and technical challenges in interdisciplinary research. For example, plasmonic nanoparticles can be assembled into well-defined configurations with high resolution limit while exhibiting desirable collective behaviors, such as near-field enhancement. Conducting metallic or polymer patterns can be synthesized site-specifically on DNA nanostructures to form various controllable geometries, which could be used for electronic nanodevices. Biomolecules can be arranged into organized networks to perform programmable biological functionalities, such as distance-dependent enzyme-cascade activities. DNA nanostructures can carry multiple cytoactive molecules and cell-targeting groups simultaneously to address medical issues such as targeted therapy and combined administration. In this Account, we describe recent advances in the functionalization of DNA nanostructures in different fashions based on our research efforts in nanophotonics, nanoelectronics, and nanomedicine. We show that DNA origami nanostructures can guide the assembly of achiral, spherical, metallic nanoparticles into nature-mimicking chiral geometries through hybridization between complementary DNA

  15. Shaping and patterning gold nanoparticles via micelle templated photochemistry

    NASA Astrophysics Data System (ADS)

    Kundrat, F.; Baffou, G.; Polleux, J.

    2015-09-01

    Shaping and positioning noble metal nanostructures are essential processes that still require laborious and sophisticated techniques to fabricate functional plasmonic interfaces. The present study reports a simple photochemical approach compatible with micellar nanolithography and photolithography that enables the growth, arrangement and shaping of gold nanoparticles with tuneable plasmonic resonances on glass substrates. Ultraviolet illumination of surfaces coated with gold-loaded micelles leads to the formation of gold nanoparticles with micro/nanometric spatial resolution without requiring any photosensitizers or photoresists. Depending on the extra-micellar chemical environment and the illumination wavelength, block copolymer micelles act as reactive and light-responsive templates, which enable to grow gold deformed nanoparticles (potatoids) and nanorings. Optical characterization reveals that arrays of individual potatoids and rings feature a localized plasmon resonance around 600 and 800 nm, respectively, enhanced photothermal properties and high temperature sustainability, making them ideal platforms for future developments in nanochemistry and biomolecular manipulation controlled by near-infrared-induced heat.Shaping and positioning noble metal nanostructures are essential processes that still require laborious and sophisticated techniques to fabricate functional plasmonic interfaces. The present study reports a simple photochemical approach compatible with micellar nanolithography and photolithography that enables the growth, arrangement and shaping of gold nanoparticles with tuneable plasmonic resonances on glass substrates. Ultraviolet illumination of surfaces coated with gold-loaded micelles leads to the formation of gold nanoparticles with micro/nanometric spatial resolution without requiring any photosensitizers or photoresists. Depending on the extra-micellar chemical environment and the illumination wavelength, block copolymer micelles act as

  16. Synthesis of Mesostructured Copper Sulfide by Cation Exchange and Liquid Crystal Templating

    SciTech Connect

    Lubeck, C R; Doyle, F M; Gash, A E; Satcher, J H; Han, T Y

    2005-08-01

    The development of synthetic pathways to yield advanced functional materials is an important aspect of materials science. In particular, the ability to control and manipulate the chemical composition and structure of inorganic nanomaterials is highly desirable. Two synthetic approaches which show great promise for producing the next generation of functional inorganic nanomaterials are (1) templating of supramolecular assemblies and (2) ion exchange within nanostructured inorganic solids to manipulate chemical composition. Templating of supramolecular assemblies of surfactants and amphiphilic polymers has already proven to be a powerful technique in synthesizing various inorganic structures. Namely, numerous examples of mesostructured metal oxides (SiO{sub 2}, TiO{sub 2}, WO{sub 3}, etc.) have been synthesized by templating the liquid crystalline phases of amphiphilic polymers and surfactants (i.e. vesicles, 2D and 3D hexagonal and cubic phases, etc.) with inorganic precursors, resulting in the formation of highly ordered inorganic-organic hybrid materials. Although the templating of supramolecular assemblies has been successful in generating highly ordered mesostructured metal oxides, there are only a few examples of non-oxidic mesostructured inorganic materials. The recent developments of ion exchange within nanoparticles offer a promising approach to generating novel nanostructured inorganic materials with unique chemical compositions. Konenkamp et al. and Alivisatos et al. have successfully utilized the ion exchange methods to fully transform the chemical composition of simple nanostructured inorganic materials while retaining their shapes. Although the exact mechanism by which the ions exchange while retaining the overall structure is still unclear, this approach combined with templating of supramolecular assemblies can provide a potent technique for obtaining highly ordered inorganic materials with unique structures and chemical compositions. Herein, we

  17. Metal Preferences and Metallation*

    PubMed Central

    Foster, Andrew W.; Osman, Deenah; Robinson, Nigel J.

    2014-01-01

    The metal binding preferences of most metalloproteins do not match their metal requirements. Thus, metallation of an estimated 30% of metalloenzymes is aided by metal delivery systems, with ∼25% acquiring preassembled metal cofactors. The remaining ∼70% are presumed to compete for metals from buffered metal pools. Metallation is further aided by maintaining the relative concentrations of these pools as an inverse function of the stabilities of the respective metal complexes. For example, magnesium enzymes always prefer to bind zinc, and these metals dominate the metalloenzymes without metal delivery systems. Therefore, the buffered concentration of zinc is held at least a million-fold below magnesium inside most cells. PMID:25160626

  18. Self-assembled SnO2 micro- and nanosphere-based gas sensor thick films from an alkoxide-derived high purity aqueous colloid precursor

    NASA Astrophysics Data System (ADS)

    Kelp, G.; Tätte, T.; Pikker, S.; Mändar, H.; Rozhin, A. G.; Rauwel, P.; Vanetsev, A. S.; Gerst, A.; Merisalu, M.; Mäeorg, U.; Natali, M.; Persson, I.; Kessler, V. G.

    2016-03-01

    Tin oxide is considered to be one of the most promising semiconductor oxide materials for use as a gas sensor. However, a simple route for the controllable build-up of nanostructured, sufficiently pure and hierarchical SnO2 structures for gas sensor applications is still a challenge. In the current work, an aqueous SnO2 nanoparticulate precursor sol, which is free of organic contaminants and sorbed ions and is fully stable over time, was prepared in a highly reproducible manner from an alkoxide Sn(OR)4 just by mixing it with a large excess of pure neutral water. The precursor is formed as a separate liquid phase. The structure and purity of the precursor is revealed using XRD, SAXS, EXAFS, HRTEM imaging, FTIR, and XRF analysis. An unconventional approach for the estimation of the particle size based on the quantification of the Sn-Sn contacts in the structure was developed using EXAFS spectroscopy and verified using HRTEM. To construct sensors with a hierarchical 3D structure, we employed an unusual emulsification technique not involving any additives or surfactants, using simply the extraction of the liquid phase, water, with the help of dry butanol under ambient conditions. The originally generated crystalline but yet highly reactive nanoparticles form relatively uniform spheres through self-assembly and solidify instantly. The spheres floating in butanol were left to deposit on the surface of quartz plates bearing sputtered gold electrodes, producing ready-for-use gas sensors in the form of ca. 50 μm thick sphere-based-films. The films were dried for 24 h and calcined at 300 °C in air before use. The gas sensitivity of the structures was tested in the temperature range of 150-400 °C. The materials showed a very quickly emerging and reversible (20-30 times) increase in electrical conductivity as a response to exposure to air containing 100 ppm of H2 or CO and short (10 s) recovery times when the gas flow was stopped.Tin oxide is considered to be one of the

  19. Fluorescent DNA-templated silver nanoclusters

    NASA Astrophysics Data System (ADS)

    Lin, Ruoqian

    Because of the ultra-small size and biocompatibility of silver nanoclusters, they have attracted much research interest for their applications in biolabeling. Among the many ways of synthesizing silver nanoclusters, DNA templated method is particularly attractive---the high tunability of DNA sequences provides another degree of freedom for controlling the chemical and photophysical properties. However, systematic studies about how DNA sequences and concentrations are controlling the photophysical properties are still lacking. The aim of this thesis is to investigate the binding mechanisms of silver clusters binding and single stranded DNAs. Here in this thesis, we report synthesis and characterization of DNA-templated silver nanoclusters and provide a systematic interrogation of the effects of DNA concentrations and sequences, including lengths and secondary structures. We performed a series of syntheses utilizing five different sequences to explore the optimal synthesis condition. By characterizing samples with UV-vis and fluorescence spectroscopy, we achieved the most proper reactants ratio and synthesis conditions. Two of them were chosen for further concentration dependence studies and sequence dependence studies. We found that cytosine-rich sequences are more likely to produce silver nanoclusters with stronger fluorescence signals; however, sequences with hairpin secondary structures are more capable in stabilizing silver nanoclusters. In addition, the fluorescence peak emission intensities and wavelengths of the DNA templated silver clusters have sequence dependent fingerprints. This potentially can be applied to sequence sensing in the future. However all the current conclusions are not warranted; there is still difficulty in formulating general rules in DNA strand design and silver nanocluster production. Further investigation of more sequences could solve these questions in the future.

  20. Protein-templated biomimetic silica nanoparticles.

    PubMed

    Jackson, Erienne; Ferrari, Mariana; Cuestas-Ayllon, Carlos; Fernández-Pacheco, Rodrigo; Perez-Carvajal, Javier; de la Fuente, Jesús M; Grazú, Valeria; Betancor, Lorena

    2015-03-31

    Biomimetic silica particles can be synthesized as a nanosized material within minutes in a process mimicked from living organisms such as diatoms and sponges. In this work, we have studied the effect of bovine serum albumin (BSA) as a template to direct the synthesis of silica nanoparticles (NPs) with the potential to associate proteins on its surface. Our approach enables the formation of spheres with different physicochemical properties. Particles using BSA as a protein template were smaller (∼250-380 nm) and were more monodisperse than those lacking the proteic core (∼700-1000 nm) as seen by dynamic light scattering (DLS), scanning electron microscopy (SEM), and environmental scanning electron microscopy (ESEM) analysis. The absence of BSA during synthesis produced silica nanoparticles without any porosity that was detectable by nitrogen adsorption, whereas particles containing BSA developed porosity in the range of 4 to 5 nm which collapsed on the removal of BSA, thus producing smaller pores. These results were in accordance with the pore size calculated by high-resolution transmission electron microscopy (HTEM). The reproducibility of the BSA-templated nanoparticle properties was determined by analyzing four batches of independent synthesizing experiments that maintained their properties. The high positive superficial charge of the nanoparticles facilitated adsorption under mild conditions of a range of proteins from an E. coli extract and a commercial preparation of laccase from Trametes versicolor. All of the proteins were quantitatively desorbed. Experiments conducted showed the reusability of the particles as supports for the ionic adsorption of the biomolecules. The protein loading capacity of the BSA-based biomimetic particles was determined using laccase as 98.7 ± 6.6 mg·g(-1) of particles.

  1. New organically templated photoluminescence iodocuprates(I)

    SciTech Connect

    Hou Qin; Zhao Jinjing; Zhao Tianqi; Jin Juan; Yu Jiehui; Xu Jiqing

    2011-07-15

    Two types of organic cyclic aliphatic diamine molecules piperazine (pip) and 1,3-bis(4-piperidyl)propane (bpp) were used, respectively, to react with an inorganic mixture of CuI and KI in the acidic CH{sub 3}OH solutions under the solvothermal conditions, generating finally three new organically templated iodocuprates as 2-D layered [(Hpip)Cu{sub 3}I{sub 4}] 1, 1-D chained [tmpip][Cu{sub 2}I{sub 4}] 2 (tmpip=N,N,N',N'-tetramethylpiperazinium) and dinuclear [H{sub 2}bpp]{sub 2}[Cu{sub 2}I{sub 5}] I.2H{sub 2}O 3. Note that the templating agent tmpip{sup 2+} in compound 2 originated from the in situ N-alkylation reaction between the pip molecule and the methanol solvent. The photoluminescence analysis indicates that the title compounds emit the different lights: yellow for 1, blue for 2 and yellow-green for 3, respectively. - Graphical abstract: The solvothermal self-assemblies of CuI, KI and pip/bpp in acidic CH{sub 3}OH solutions created three iodocuprates 2-D layered [(Hpip)Cu{sub 3}I{sub 4}] 1, 1-D chained [tmpip][Cu{sub 2}I{sub 4}] 2 and dinuclear [H{sub 2}bpp]{sub 2}[Cu{sub 2}I{sub 5}] I.2H{sub 2}O 3. Highlights: > A new layered iodocuprate(I) with 20-membered rings was hydrothermally prepared. > A simple approach to prepare the new organic templating agent was reported. > Photoluminescence analysis indicates the emission for iodocuprate(I) is associated with the Cu...Cu interactions.

  2. Template for Systems Engineering Tools Trade Study

    NASA Technical Reports Server (NTRS)

    Bailey, Michelle D.

    2005-01-01

    A discussion of Systems Engineering tools brings out numerous preferences and reactions regarding tools of choice as well as the functions those tools are to perform. A recent study of Systems Engineering Tools for a new Program illustrated the need for a generic template for use by new Programs or Projects to determine the toolset appropriate for their use. This paper will provide the guidelines new initiatives can follow and tailor to their specific needs, to enable them to make their choice of tools in an efficient and informed manner. Clearly, those who perform purely technical functions will need different tools than those who perform purely systems engineering functions. And, everyone has tools they are comfortable with. That degree of comfort is frequently the deciding factor in tools choice rather than an objective study of all criteria and weighting factors. This paper strives to produce a comprehensive list of criteria for selection with suggestions for weighting factors based on a number of assumptions regarding the given Program or Project. In addition, any given Program will begin with assumptions for its toolset based on Program size, tool cost, user base and technical needs. In providing a template for tool selection, this paper will guide the reader through assumptions based on Program need; decision criteria; potential weighting factors; the need for a compilation of available tools; the importance of tool demonstrations; and finally a down selection of tools. While specific vendors cannot be mentioned in this work, it is expected that this template could serve other Programs in the formulation phase by alleviating the trade study process of some of its subjectivity.

  3. Generating Test Templates via Automated Theorem Proving

    NASA Technical Reports Server (NTRS)

    Kancherla, Mani Prasad

    1997-01-01

    Testing can be used during the software development process to maintain fidelity between evolving specifications, program designs, and code implementations. We use a form of specification-based testing that employs the use of an automated theorem prover to generate test templates. A similar approach was developed using a model checker on state-intensive systems. This method applies to systems with functional rather than state-based behaviors. This approach allows for the use of incomplete specifications to aid in generation of tests for potential failure cases. We illustrate the technique on the cannonical triangle testing problem and discuss its use on analysis of a spacecraft scheduling system.

  4. Template-directed porous electrodes in electroanalysis.

    PubMed

    Walcarius, Alain

    2010-01-01

    Nano- and/or macrostructuring of electrode surfaces has recently emerged as a powerful method of improving the performances of electrochemical devices by enhancing both molecular accessibility and rapid mass transport via diffusion, by increasing the electroactive surface area in comparison to the geometric one, and/or by providing confinement platforms for hosting suitable reagents. This brief overview highlights how template technology offers advantages in terms of designing new types of porous electrodes-mostly based on thin films, and functionalized or not-and discusses their use in analytical chemistry via some recent examples from the literature on electrochemical sensors and biosensors.

  5. Automatic target detection using binary template matching

    NASA Astrophysics Data System (ADS)

    Jun, Dong-San; Sun, Sun-Gu; Park, HyunWook

    2005-03-01

    This paper presents a new automatic target detection (ATD) algorithm to detect targets such as battle tanks and armored personal carriers in ground-to-ground scenarios. Whereas most ATD algorithms were developed for forward-looking infrared (FLIR) images, we have developed an ATD algorithm for charge-coupled device (CCD) images, which have superior quality to FLIR images in daylight. The proposed algorithm uses fast binary template matching with an adaptive binarization, which is robust to various light conditions in CCD images and saves computation time. Experimental results show that the proposed method has good detection performance.

  6. The breakage of nanopore in AAO template

    NASA Astrophysics Data System (ADS)

    Jia, X. R.; Wang, H.; Zhen, Y.

    2016-07-01

    In the present work, AAO template is fabricated in oxalic acid solution under a constant voltage by several steps. By the Bernoulli principle, the pressure on the wall of hole increases which lead to the breakage of nanopore as a result of the reducing effective migration rate of Al3+. The quantity of the breakage of nanopore rises with the increase of the concentration of Al3+. Further, nanopore is closed by oxide due to the decrease of effective migration rate of Al3+. Finally, a “nanoflower-like” shape can be observed in experiments.

  7. The Contextualization of Archetypes: Clinical Template Governance.

    PubMed

    Pedersen, Rune; Ulriksen, Gro-Hilde; Ellingsen, Gunnar

    2015-01-01

    This paper is a status report from a large-scale openEHR-based EPR project from the North Norway Regional Health Authority. It concerns the standardization of a regional ICT portfolio and the ongoing development of a new process oriented EPR systems encouraged by the unfolding of a national repository for openEHR archetypes. Subject of interest; the contextualization of clinical templates is governed over multiple national boundaries which is complex due to the dependency of clinical resources. From the outset of this, we are interested in how local, regional, and national organizers maneuver to standardize while applying OpenEHR technology. PMID:26262546

  8. Hierarchically structured porous cadmium selenide polycrystals using polystyrene bilayer templates.

    PubMed

    Park, Jin Young; Hendricks, Nicholas R; Carter, Kenneth R

    2012-09-18

    In this study, a novel approach is demonstrated to fabricate hierarchically structured cadmium selenide (CdSe) layers with size-tunable nano/microporous morphologies achieved using polystyrene (PS) bilayered templates (top layer: colloidal template) via potentiostatic electrochemical deposition. The PS bilayer template is made in two steps. First, various PS patterns (stripes, ellipsoids, and circles) are prepared as the bottom layers through imprint lithography. In a second step, a top template is deposited that consists of a self-assembled layer of colloidal 2D packed PS particles. Electrochemical growth of CdSe crystals in the voids and selective removal of the PS bilayered templates give rise to hierarchically patterned 2D hexagonal porous CdSe structures. This simple and facile technique provides various unconventional porous CdSe films, arising from the effect of the PS bottom templates.

  9. Assessing usage patterns of electronic clinical documentation templates.

    PubMed

    Vawdrey, David K

    2008-11-06

    Many vendors of electronic medical records support structured and free-text entry of clinical documents using configurable templates. At a healthcare institution comprising two large academic medical centers, a documentation management data mart and a custom, Web-accessible business intelligence application were developed to track the availability and usage of electronic documentation templates. For each medical center, template availability and usage trends were measured from November 2007 through February 2008. By February 2008, approximately 65,000 electronic notes were authored per week on the two campuses. One site had 934 available templates, with 313 being used to author at least one note. The other site had 765 templates, of which 480 were used. The most commonly used template at both campuses was a free text note called "Miscellaneous Nursing Note," which accounted for 33.3% of total documents generated at one campus and 15.2% at the other.

  10. Human identification using temporal information preserving gait template.

    PubMed

    Wang, Chen; Zhang, Junping; Wang, Liang; Pu, Jian; Yuan, Xiaoru

    2012-11-01

    Gait Energy Image (GEI) is an efficient template for human identification by gait. However, such a template loses temporal information in a gait sequence, which is critical to the performance of gait recognition. To address this issue, we develop a novel temporal template, named Chrono-Gait Image (CGI), in this paper. The proposed CGI template first extracts the contour in each gait frame, followed by encoding each of the gait contour images in the same gait sequence with a multichannel mapping function and compositing them to a single CGI. To make the templates robust to a complex surrounding environment, we also propose CGI-based real and synthetic temporal information preserving templates by using different gait periods and contour distortion techniques. Extensive experiments on three benchmark gait databases indicate that, compared with the recently published gait recognition approaches, our CGI-based temporal information preserving approach achieves competitive performance in gait recognition with robustness and efficiency. PMID:22201053

  11. Assessing usage patterns of electronic clinical documentation templates.

    PubMed

    Vawdrey, David K

    2008-01-01

    Many vendors of electronic medical records support structured and free-text entry of clinical documents using configurable templates. At a healthcare institution comprising two large academic medical centers, a documentation management data mart and a custom, Web-accessible business intelligence application were developed to track the availability and usage of electronic documentation templates. For each medical center, template availability and usage trends were measured from November 2007 through February 2008. By February 2008, approximately 65,000 electronic notes were authored per week on the two campuses. One site had 934 available templates, with 313 being used to author at least one note. The other site had 765 templates, of which 480 were used. The most commonly used template at both campuses was a free text note called "Miscellaneous Nursing Note," which accounted for 33.3% of total documents generated at one campus and 15.2% at the other. PMID:18998863

  12. Molecular engineering of porous silica using aryl templates

    DOEpatents

    Loy, D.A.; Shea, K.J.

    1994-06-14

    A process is described for manipulating the porosity of silica using a series of organic template groups covalently incorporated into the silicate matrix. The templates in the bridged polysilsesquioxanes are selectively removed from the material by oxidation with oxygen plasma or other means, leaving engineered voids or pores. The size of these pores is dependent upon the length or size of the template or spacer. The size of the templates is measured in terms of Si-Si distances which range from about 0.67 nm to 1.08 nm. Changes introduced by the loss of the templates result in a narrow range of micropores (i.e. <2 nm). Both aryl and alkyl template groups are used as spacers. Novel microporous silica materials useful as molecular sieves, desiccants, and catalyst supports are produced. 3 figs.

  13. Molecular engineering of porous silica using aryl templates

    DOEpatents

    Loy, Douglas A.; Shea, Kenneth J.

    1994-01-01

    A process for manipulating the porosity of silica using a series of organic template groups covalently incorporated into the silicate matrix. The templates in the bridged polysilsesquioxanes are selectively removed from the material by oxidation with oxygen plasma or other means, leaving engineered voids or pores. The size of these pores is dependent upon the length or size of the template or spacer. The size of the templates is measured in terms of Si-Si distances which range from about 0.67 nm to 1.08 nm. Changes introduced by the loss of the templates result in a narrow range of micropores (i.e. <2 nm). Both aryl and alkyl template groups are used as spacers. Novel microporous silica materials useful as molecular seives, dessicants, and catalyst supports are produced.

  14. Facile fabrication of high-quality Ag/PS coaxial nanocables based on the mixed mode of soft/hard templates

    PubMed Central

    Wan, Mimi; Zhao, Wenbo; Peng, Fang; Wang, Qi; Xu, Ping; Mao, Chun; Shen, Jian

    2016-01-01

    A new kind of high-quality Ag/PS coaxial nanocables can be facilely synthesized by using soft/hard templates method. In order to effectively introduce Ag sources into porous polystyrene (PS) nanotubes which were trapped in porous anodic aluminum oxide (AAO) hard template, Pluronic F127 (F127) was used as guiding agent, soft template and reductant. Meanwhile, ethylene glycol solution was also used as solvent and co-reducing agent to assist in the formation of silver nanowires. The influences of concentration of F127 and reducing reaction time on the formation of Ag/PS coaxial nanocables were discussed. Results indicated that the high-quality Ag/PS coaxial nanocables can be obtained by the mixed mode of soft/hard templates under optimized conditions. This strategy is expected to be extended to design more metal/polymer coaxial nanocables for the benefit of creation of complex and functional nanoarchitectures and components. PMID:27477888

  15. Facile fabrication of high-quality Ag/PS coaxial nanocables based on the mixed mode of soft/hard templates

    NASA Astrophysics Data System (ADS)

    Wan, Mimi; Zhao, Wenbo; Peng, Fang; Wang, Qi; Xu, Ping; Mao, Chun; Shen, Jian

    2016-08-01

    A new kind of high-quality Ag/PS coaxial nanocables can be facilely synthesized by using soft/hard templates method. In order to effectively introduce Ag sources into porous polystyrene (PS) nanotubes which were trapped in porous anodic aluminum oxide (AAO) hard template, Pluronic F127 (F127) was used as guiding agent, soft template and reductant. Meanwhile, ethylene glycol solution was also used as solvent and co-reducing agent to assist in the formation of silver nanowires. The influences of concentration of F127 and reducing reaction time on the formation of Ag/PS coaxial nanocables were discussed. Results indicated that the high-quality Ag/PS coaxial nanocables can be obtained by the mixed mode of soft/hard templates under optimized conditions. This strategy is expected to be extended to design more metal/polymer coaxial nanocables for the benefit of creation of complex and functional nanoarchitectures and components.

  16. Novel encoding methods for DNA-templated chemical libraries.

    PubMed

    Li, Gang; Zheng, Wenlu; Liu, Ying; Li, Xiaoyu

    2015-06-01

    Among various types of DNA-encoded chemical libraries, DNA-templated library takes advantage of the sequence-specificity of DNA hybridization, enabling not only highly effective DNA-templated chemical reactions, but also high fidelity in library encoding. This brief review summarizes recent advances that have been made on the encoding strategies for DNA-templated libraries, and it also highlights their respective advantages and limitations for the preparation of DNA-encoded libraries.

  17. Macrocycle Synthesis by Chloride-Templated Amide Bond Formation.

    PubMed

    Martí-Centelles, Vicente; Burguete, M Isabel; Luis, Santiago V

    2016-03-01

    A new family of pseudopeptidic macrocyclic compounds has been prepared involving an anion-templated amide bond formation reaction at the macrocyclization step. Chloride anion was found to be the most efficient template in the macrocyclization process, producing improved macrocyclization yields with regard to the nontemplated reaction. The data suggest a kinetic effect of the chloride template, providing an appropriate folded conformation of the open-chain precursor and reducing the energy barrier for the formation of the macrocyclic product. PMID:26820908

  18. Research of Search Template Based on Distributed Computing

    NASA Astrophysics Data System (ADS)

    Xiao, Yao; Huang, Long-Jun; Zuo, Yi

    Aiming at the problem of requirement identification in the field of search engine, we proposed a scheme that makes use of nature language template. In the help of map-reduce analyze of the user searching log, high frequency template can be obtained. Besides, based on tire tree we designed a algorithm that can make the search engine distinguish user requirements using the template. In that case, the search engine can offer different service according to the user requirements.

  19. Modifiable templates facilitate customization of physician order entry.

    PubMed

    Franklin, M J; Sittig, D F; Schmiz, J L; Spurr, C D; Thomas, D; O'Connell, E M; Teich, J M

    1998-01-01

    Physician order entry is a key factor in improving the quality of healthcare, while simultaneously reducing its cost. This paper describes an editor, a database, and a run-time system for creating and executing highly customized, user modifiable, order entry templates. The system allows non-programmers to create new order entry templates rapidly. Over the past 18 months, the templates have been used on over 2500 patients to enter over 40,000 separate orders.

  20. A nanocluster beacon based on the template transformation of DNA-templated silver nanoclusters.

    PubMed

    Teng, Ye; Jia, Xiaofang; Zhang, Shan; Zhu, Jinbo; Wang, Erkang

    2016-01-28

    In this work, we developed a novel light-up nanocluster beacon (NCB) based on shuttling dark silver nanoclusters (NCs) to a bright scaffold through hybridization. The fluorescence enhancement was as high as 70-fold when the two templates were on the opposite sides of the duplexes, enabling sensitive and selective detection of DNA.

  1. Two methods to generate templates for template-based partial volume effect correction: SPECT phantom experiments.

    PubMed

    Shcherbinin, S; Grimes, J; Celler, A

    2013-02-21

    In this paper, we explore the applicability of template-based compensation for the partial volume effect (PVE) for situations where (i) the image has multiple uptake sites (tumors and organs) but only one of them is treated as a region of interest (ROI) with the boundaries available from a high-resolution modality and (ii) no information regarding activities inside or outside this ROI is a priori available. We modeled this situation by performing SPECT acquisitions of phantoms containing 21 containers, which had different shapes and sizes and were filled with different levels of activity. In our analysis, each of these containers was treated as an individual ROI. We compared the performance of two methods of template construction. In method 1, the ROI template value was obtained from a conventionally reconstructed (without PVEC) image. In method 2, the ROI template value was directly (bypassing the PVE-affected conventional image) calculated from projections using region-based reconstruction. Our processing shows that method 1 resulted in consistent (activities for all 21 ROIs were improved) but relatively weak PVE compensation (errors of recovered total activities were equal to or lower than 10% for 5 ROIs only). Application of method 2 resulted in a selective (activities for 19 ROIs were improved) but considerably better compensation when compared to method 1 (errors of recovered total activities were equal to or lower than 10% for 10 ROIs).

  2. Self-templated formation of uniform NiCo2O4 hollow spheres with complex interior structures for lithium-ion batteries and supercapacitors.

    PubMed

    Shen, Laifa; Yu, Le; Yu, Xin-Yao; Zhang, Xiaogang; Lou, Xiong Wen David

    2015-02-01

    Despite the significant advancement in preparing metal oxide hollow structures, most approaches rely on template-based multistep procedures for tailoring the interior structure. In this work, we develop a new generally applicable strategy toward the synthesis of mixed-metal-oxide complex hollow spheres. Starting with metal glycerate solid spheres, we show that subsequent thermal annealing in air leads to the formation of complex hollow spheres of the resulting metal oxide. We demonstrate the concept by synthesizing highly uniform NiCo2O4 hollow spheres with a complex interior structure. With the small primary building nanoparticles, high structural integrity, complex interior architectures, and enlarged surface area, these unique NiCo2O4 hollow spheres exhibit superior electrochemical performances as advanced electrode materials for both lithium-ion batteries and supercapacitors. This approach can be an efficient self-templated strategy for the preparation of mixed-metal-oxide hollow spheres with complex interior structures and functionalities.

  3. Light Weight Biomorphous Cellular Ceramics from Cellulose Templates

    NASA Technical Reports Server (NTRS)

    Singh, Mrityunjay; Yee, Bo-Moon; Gray, Hugh R. (Technical Monitor)

    2003-01-01

    Bimorphous ceramics are a new class of materials that can be fabricated from the cellulose templates derived from natural biopolymers. These biopolymers are abundantly available in nature and are produced by the photosynthesis process. The wood cellulose derived carbon templates have three- dimensional interconnectivity. A wide variety of non-oxide and oxide based ceramics have been fabricated by template conversion using infiltration and reaction-based processes. The cellular anatomy of the cellulose templates plays a key role in determining the processing parameters (pyrolysis, infiltration conditions, etc.) and resulting ceramic materials. The processing approach, microstructure, and mechanical properties of the biomorphous cellular ceramics (silicon carbide and oxide based) have been discussed.

  4. Directed self-assembly graphoepitaxy template generation with immersion lithography

    NASA Astrophysics Data System (ADS)

    Ma, Yuansheng; Lei, Junjiang; Andres Torres, J.; Hong, Le; Word, James; Fenger, Germain; Tritchkov, Alexander; Lippincott, George; Gupta, Rachit; Lafferty, Neal; He, Yuan; Bekaert, Joost; Vanderberghe, Geert

    2015-07-01

    We present an optimization methodology for the template designs of subresolution contacts using directed self-assembly (DSA) with graphoepitaxy and immersion lithography. We demonstrate the flow using a 60-nm-pitch contact design in doublet with Monte Carlo simulations for DSA. We introduce the notion of template error enhancement factor (TEEF) to gauge the sensitivity of DSA printing infidelity to template printing infidelity and evaluate optimized template designs with TEEF metrics. Our data show that source mask optimization and inverse lithography technology are critical to achieve sub-80 nm non-L0 pitches for DSA patterns using 193i.

  5. Piled tool will level subsea well template for Heidrun TLP

    SciTech Connect

    Not Available

    1992-01-13

    This paper reports on piled leveling tools that were contracted for use during the installation of the subsea well template for Conoco Norway Inc.'s Heidrun tension leg platform (TLP) in the Norwegian sector of the North Sea. The leveling tools are employed after a template has been positioned on the seafloor and anchor pilings have been driven through the template sleeves. One or more tools are lowered and landed on anchor pilings at the low side of the template. No diver support or guidelines are required.

  6. Bias in template-to-product ratios in multitemplate PCR.

    PubMed

    Polz, M F; Cavanaugh, C M

    1998-10-01

    Bias introduced by the simultaneous amplification of specific genes from complex mixtures of templates remains poorly understood. To explore potential causes and the extent of bias in PCR amplification of 16S ribosomal DNAs (rDNAs), genomic DNAs of two closely and one distantly related bacterial species were mixed and amplified with universal, degenerate primers. Quantification and comparison of template and product ratios showed that there was considerable and reproducible overamplification of specific templates. Variability between replicates also contributed to the observed bias but in a comparatively minor way. Based on these initial observations, template dosage and differences in binding energies of permutations of the degenerate, universal primers were tested as two likely causes of this template-specific bias by using 16S rDNA templates modified by site-directed mutagenesis. When mixtures of mutagenized templates containing AT- and GC-rich priming sites were used, templates containing the GC-rich permutation amplified with higher efficiency, indicating that different primer binding energies may to a large extent be responsible for overamplification. In contrast, gene copy number was found to be an unlikely cause of the observed bias. Similarly, amplification from DNA extracted from a natural community to which different amounts of genomic DNA of a single bacterial species were added did not affect relative product ratios. Bias was reduced considerably by using high template concentrations, by performing fewer cycles, and by mixing replicate reaction preparations.

  7. Microporous silica prepared by organic templating: Relationship between the molecular template and pore structure

    SciTech Connect

    Lu, Y.; Brinker, C.J. |; Cao, G.; Kale, R.P.; Prabakar, S.; Lopez, G.P.

    1999-05-01

    Microporous silica materials with a controlled pore size and a narrow pore size distribution have been prepared by sol-gel processing using an organic-templating approach. Microporous networks were formed by pyrolytic removal of organic ligands (methacryloxypropyl groups) from organic/inorganic hybrid materials synthesized by copolymerization of 3-methacryloxypropylsilane (MPS) and tetraethoxysilane (TEOS). Molecular simulations and experimental measurements were conducted to examine the relationship between the microstructural characteristics of the porous silica (e.g., pore size, total pore volume, and pore connectivity) and the size and amount of organic template ligands added. Adsorption measurements suggest that the final porosity of the microporous silica is due to both primary pores (those present in the hybrid material prior to pyrolysis) and secondary pores (those created by pyrolytic removal of organic templates). Primary pores were inaccessible to N{sub 2} at 77 K but accessible to CO{sub 2} at 195 K; secondary pores were accessible to both N{sub 2} (at 77 K) and CO{sub 2} (at 195 K) in adsorption measurements. Primary porosity decreases with the amount of organic ligands added because of the enhanced densification of MPS/TEOS hybrid materials as the mole fraction of trifunctional MPS moieties increases. Pore volumes measured by nitrogen adsorption experiments at 77 K suggest that the secondary (template-derived) porosity exhibits a percolation behavior as the template concentration is increased. Gas permeation experiments indicate that the secondary pores are approximately 5 {angstrom} in diameter, consistent with predictions based on molecular simulations.

  8. Adaptive, template moderated, spatially varying statistical classification.

    PubMed

    Warfield, S K; Kaus, M; Jolesz, F A; Kikinis, R

    2000-03-01

    A novel image segmentation algorithm was developed to allow the automatic segmentation of both normal and abnormal anatomy from medical images. The new algorithm is a form of spatially varying statistical classification, in which an explicit anatomical template is used to moderate the segmentation obtained by statistical classification. The algorithm consists of an iterated sequence of spatially varying classification and nonlinear registration, which forms an adaptive, template moderated (ATM), spatially varying statistical classification (SVC). Classification methods and nonlinear registration methods are often complementary, both in the tasks where they succeed and in the tasks where they fail. By integrating these approaches the new algorithm avoids many of the disadvantages of each approach alone while exploiting the combination. The ATM SVC algorithm was applied to several segmentation problems, involving different image contrast mechanisms and different locations in the body. Segmentation and validation experiments were carried out for problems involving the quantification of normal anatomy (MRI of brains of neonates) and pathology of various types (MRI of patients with multiple sclerosis, MRI of patients with brain tumors, MRI of patients with damaged knee cartilage). In each case, the ATM SVC algorithm provided a better segmentation than statistical classification or elastic matching alone. PMID:10972320

  9. Physical and Morphological Characterization of Templated Thermosets

    NASA Astrophysics Data System (ADS)

    Hermel-Davidock, Theresa J.

    2005-03-01

    It has been found that by the addition of low concentrations of an amphiphilic block copolymer to an epoxy resin, novel disordered morphologies can be formed and preserved through cure. It has also been found that the addition of small amounts of block copolymer can improve the fracture resistance significantly without sacrificing the high modulus and glass transition temperature of these thermoset materials. This report will focus on characterizing the influence of the block copolymer and casting solvent on the morphology achieved in the thermoset sample and the resulting physical properties. Templated thermoset samples exhibiting two different diblock copolymer morphologies, worm-like micelles and spherical micelles were investigated. The micro-deformation mechanisms of these templated thermosets were studied via an in-situ tensile deformation technique performed in a transmission electron microscope (TEM). The micro-deformation behaviors of these samples were found to correlate well with the macroscopic mechanical properties. The toughening effect obtained in the epoxy resin was attributed to the well-dispersed worm-like morphology and the weak interfacial adhesion between the micelles and the matrix.

  10. Kinetic theory of amyloid fibril templating.

    PubMed

    Schmit, Jeremy D

    2013-05-14

    The growth of amyloid fibrils requires a disordered or partially unfolded protein to bind to the fibril and adapt the same conformation and alignment established by the fibril template. Since the H-bonds stabilizing the fibril are interchangeable, it is inevitable that H-bonds form between incorrect pairs of amino acids which are either incorporated into the fibril as defects or must be broken before the correct alignment can be found. This process is modeled by mapping the formation and breakage of H-bonds to a one-dimensional random walk. The resulting microscopic model of fibril growth is governed by two timescales: the diffusion time of the monomeric proteins, and the time required for incorrectly bound proteins to unbind from the fibril. The theory predicts that the Arrhenius behavior observed in experiments is due to off-pathway states rather than an on-pathway transition state. The predicted growth rates are in qualitative agreement with experiments on insulin fibril growth rates as a function of protein concentration, denaturant concentration, and temperature. These results suggest a templating mechanism where steric clashes due to a single mis-aligned molecule prevent the binding of additional molecules.

  11. A Facile Strategy for In Situ Core-Template-Functionalizing Siliceous Hollow Nanospheres for Guest Species Entrapment

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Gao, Xin; Yang, Xianyan; Gan, Yilai; Weng, Wenjian; Gou, Zhongru

    2009-10-01

    The shell wall-functionalized siliceous hollow nanospheres (SHNs) with functional molecules represent an important class of nanocarriers for a rich range of potential applications. Herein, a self-templated approach has been developed for the synthesis of in situ functionalized SHNs, in which the biocompatible long-chain polycarboxylates (i.e., polyacrylate, polyaspartate, gelatin) provide the framework for silica precursor deposition by simply controlling chain conformation with divalent metal ions (i.e., Ca2+, Sr2+), without the intervention of any external templates. Metal ions play crucial roles in the formation of organic vesicle templates by modulating the long chains of polymers and preventing them from separation by washing process. We also show that, by in situ functionalizing the shell wall of SHNs, it is capable of entrapping nearly an eightfold quantity of vitamin Bc in comparison to the bare bulk silica nanospheres. These results confirm the feasibility of guest species entrapment in the functionalized shell wall, and SHNs are effective carriers of guest (bio-)molecules potentially for a variety of biomedical applications. By rationally choosing the functional (self-templating) molecules, this concept may represent a general strategy for the production of functionalized silica hollow structures.

  12. Two dimensional template matching method for buried object discrimination in GPR data

    NASA Astrophysics Data System (ADS)

    Sezgin, Mehmet

    2009-05-01

    In this study discrimination of two different metallic object classes were studied, utilizing Ground Penetrating Radar (GPR). Feature sets of both classes have almost the same information for both Metal Detector (MD) and GPR data. There were no evident features those are easily discriminate classes. Background removal has been applied to original B-Scan data and then a normalization process was performed. Image thresholding was applied to segment B-Scan GPR images. So, main hyperbolic shape of buried object reflection was extracted and then a morphological process was performed optionally. Templates of each class representatives have been obtained and they were searched whether they match with true class or not. Two data sets were examined experimentally. Actually they were obtained in different time and burial for the same objects. Considerably high discrimination performance was obtained which was not possible by using individual Metal Detector data.

  13. Vacuum template synthesis of multifunctional nanotubes with tailored nanostructured walls

    PubMed Central

    Filippin, A. Nicolas; Macias-Montero, Manuel; Saghi, Zineb; Idígoras, Jesús; Burdet, Pierre; Barranco, Angel; Midgley, Paul; Anta, Juan A.; Borras, Ana

    2016-01-01

    A three-step vacuum procedure for the fabrication of vertical TiO2 and ZnO nanotubes with three dimensional walls is presented. The method combines physical vapor deposition of small-molecules, plasma enhanced chemical vapor deposition of inorganic functional thin films and layers and a post-annealing process in vacuum in order to remove the organic template. As a result, an ample variety of inorganic nanotubes are made with tunable length, hole dimensions and shapes and tailored wall composition, microstructure, porosity and structure. The fabrication of multishell nanotubes combining different semiconducting oxides and metal nanoparticles is as well explored. This method provides a feasible and reproducible route for the fabrication of high density arrays of vertically alligned nanotubes on processable substrates. The emptying mechanism and microstructure of the nanotubes have been elucidated through SEM, STEM, HAADF-STEM tomography and energy dispersive X-ray spectroscopy. In this article, as a proof of concept, it is presented the straightforward integration of ZnO nanotubes as photoanode in a photovoltaic cell and as a photonic oxygen gas sensor. PMID:26860367

  14. Vacuum template synthesis of multifunctional nanotubes with tailored nanostructured walls.

    PubMed

    Filippin, A Nicolas; Macias-Montero, Manuel; Saghi, Zineb; Idígoras, Jesús; Burdet, Pierre; Barranco, Angel; Midgley, Paul; Anta, Juan A; Borras, Ana

    2016-02-10

    A three-step vacuum procedure for the fabrication of vertical TiO2 and ZnO nanotubes with three dimensional walls is presented. The method combines physical vapor deposition of small-molecules, plasma enhanced chemical vapor deposition of inorganic functional thin films and layers and a post-annealing process in vacuum in order to remove the organic template. As a result, an ample variety of inorganic nanotubes are made with tunable length, hole dimensions and shapes and tailored wall composition, microstructure, porosity and structure. The fabrication of multishell nanotubes combining different semiconducting oxides and metal nanoparticles is as well explored. This method provides a feasible and reproducible route for the fabrication of high density arrays of vertically alligned nanotubes on processable substrates. The emptying mechanism and microstructure of the nanotubes have been elucidated through SEM, STEM, HAADF-STEM tomography and energy dispersive X-ray spectroscopy. In this article, as a proof of concept, it is presented the straightforward integration of ZnO nanotubes as photoanode in a photovoltaic cell and as a photonic oxygen gas sensor.

  15. Vacuum template synthesis of multifunctional nanotubes with tailored nanostructured walls

    NASA Astrophysics Data System (ADS)

    Filippin, A. Nicolas; Macias-Montero, Manuel; Saghi, Zineb; Idígoras, Jesús; Burdet, Pierre; Barranco, Angel; Midgley, Paul; Anta, Juan A.; Borras, Ana

    2016-02-01

    A three-step vacuum procedure for the fabrication of vertical TiO2 and ZnO nanotubes with three dimensional walls is presented. The method combines physical vapor deposition of small-molecules, plasma enhanced chemical vapor deposition of inorganic functional thin films and layers and a post-annealing process in vacuum in order to remove the organic template. As a result, an ample variety of inorganic nanotubes are made with tunable length, hole dimensions and shapes and tailored wall composition, microstructure, porosity and structure. The fabrication of multishell nanotubes combining different semiconducting oxides and metal nanoparticles is as well explored. This method provides a feasible and reproducible route for the fabrication of high density arrays of vertically alligned nanotubes on processable substrates. The emptying mechanism and microstructure of the nanotubes have been elucidated through SEM, STEM, HAADF-STEM tomography and energy dispersive X-ray spectroscopy. In this article, as a proof of concept, it is presented the straightforward integration of ZnO nanotubes as photoanode in a photovoltaic cell and as a photonic oxygen gas sensor.

  16. Crystal chemistry of three new monodimensional fluorometalates templated with ethylenediamine

    NASA Astrophysics Data System (ADS)

    Lhoste, J.; Gervier, R.; Maisonneuve, V.; Leblanc, M.; Adil, K.

    2009-09-01

    Three new monodimensional hybrid metal (Ti, In, Al) fluorides are synthesized with ethylenediamine ( en) as a templating agent in solvothermal conditions assisted by microwave heating. All structures involve inorganic chains built up from TiO 2F 4 octahedra connected by two opposite O 2- vertices in [H 2en]·(TiOF 4) ( I), from InF 6(H 2O) pentagonal bipyramids linked by F-F edges in [H 2en]·(InF 4(H 2O)) 2·H 2O ( II) and from (Al 7F 30) 9- polyanions sharing two opposite AlF 6 octahedra in [H 2en] 3·(Al 6F 24) ( III). I is tetragonal, P4/ ncc, a = 12.761(3) Å, c = 8.041(3) Å; II is orthorhombic, F2 dd, a = 6.904(5) Å, b = 16.559(5) Å, c = 19.777(4) Å and III is monoclinic, P2 1/n, a = 9.387(2) Å, b = 6.710(2) Å, c = 21.513(6) Å, β = 97.18(3)°.

  17. Vacuum template synthesis of multifunctional nanotubes with tailored nanostructured walls.

    PubMed

    Filippin, A Nicolas; Macias-Montero, Manuel; Saghi, Zineb; Idígoras, Jesús; Burdet, Pierre; Barranco, Angel; Midgley, Paul; Anta, Juan A; Borras, Ana

    2016-01-01

    A three-step vacuum procedure for the fabrication of vertical TiO2 and ZnO nanotubes with three dimensional walls is presented. The method combines physical vapor deposition of small-molecules, plasma enhanced chemical vapor deposition of inorganic functional thin films and layers and a post-annealing process in vacuum in order to remove the organic template. As a result, an ample variety of inorganic nanotubes are made with tunable length, hole dimensions and shapes and tailored wall composition, microstructure, porosity and structure. The fabrication of multishell nanotubes combining different semiconducting oxides and metal nanoparticles is as well explored. This method provides a feasible and reproducible route for the fabrication of high density arrays of vertically alligned nanotubes on processable substrates. The emptying mechanism and microstructure of the nanotubes have been elucidated through SEM, STEM, HAADF-STEM tomography and energy dispersive X-ray spectroscopy. In this article, as a proof of concept, it is presented the straightforward integration of ZnO nanotubes as photoanode in a photovoltaic cell and as a photonic oxygen gas sensor. PMID:26860367

  18. Non-templated ambient nanoperforation of graphene: a novel scalable process and its exploitation for energy and environmental applications

    NASA Astrophysics Data System (ADS)

    Jhajharia, Suman Kumari; Selvaraj, Kaliaperumal

    2015-11-01

    Nano-perforation of 2D graphene sheets is a recent and strategically significant means to exploit such materials in modern applications such as energy production and storage. However, current options for the synthesis of holey graphene (hG) through nano-perforation of graphene involve industrially undesirable steps viz., usage of expensive/noble metal or silica nanoparticle templates and/or hazardous chemicals. This severely hampers its scope for large scale production and further exploitation. Herein, we report for the first time a scalable non-templated route to produce hG at ambient conditions. Nano-perforation is achieved with tunable pore size via the simple few layer co-assembly of silicate-surfactant admicelles along the surface of graphene oxide. A gentle alkali treatment and a reduction at optimized conditions readily yielded holey graphene with a remarkable capacitance (~250 F g-1) and interesting adsorption abilities for pollutants. Density functional theory based computational studies reveal interesting insights on the template free nano-perforation at a molecular level. This simple rapid process not only excludes the need for expensive templates and harmful chemicals to yield hG at attractively ambient, chemically placid and industrially safer conditions, but also creates no hurdles in terms of scaling up.Nano-perforation of 2D graphene sheets is a recent and strategically significant means to exploit such materials in modern applications such as energy production and storage. However, current options for the synthesis of holey graphene (hG) through nano-perforation of graphene involve industrially undesirable steps viz., usage of expensive/noble metal or silica nanoparticle templates and/or hazardous chemicals. This severely hampers its scope for large scale production and further exploitation. Herein, we report for the first time a scalable non-templated route to produce hG at ambient conditions. Nano-perforation is achieved with tunable pore size

  19. Surfactant-Templated Synthesis of Polypyrrole Nanocages as Redox Mediators for Efficient Energy Storage

    NASA Astrophysics Data System (ADS)

    Ahn, Ki-Jin; Lee, Younghee; Choi, Hojin; Kim, Min-Sik; Im, Kyungun; Noh, Seonmyeong; Yoon, Hyeonseok

    2015-09-01

    Preparation of conducting-polymer hollow nanoparticles with different diameters was accomplished by surfactant templating. An anionic surfactant, namely sodium dodecylbenzenesulfonate, formed vesicles to template with the pyrrole monomer. Subsequent chemical oxidative polymerization of the monomer yielded spherical polypyrrole (PPy) nanoparticles with hollow interiors. The diameter of the hollow nanoparticles was easily controlled by adjusting the concentration of the surfactant. Subsequently, the size-dependent electrochemical properties of the nanoparticles, including redox properties and charge/discharge behavior, were examined. By virtue of the structural advantages, the specific capacitance (max. 326 F g-1) of PPy hollow nanoparticles was approximately twice as large as that of solid PPy nanospheres. The hollow PPy nanostructure can easily be used as a conductive substrate for the preparation of metal/polymer nanohybrids through chemical and electrochemical deposition. Two different pseudocapacitive metal-oxide clusters were readily deposited on the inner and outer surfaces of the hollow nanoparticles, which resulted in an increase in the specific capacitance to 390 F g-1. In addition, the hollow nanoparticles acted as a nanocage to prevent metal ion leaching during charge/discharge, thus allowing an excellent capacitance retention of ca. 86%, even following 10,000 cycles.

  20. Surfactant-Templated Synthesis of Polypyrrole Nanocages as Redox Mediators for Efficient Energy Storage

    PubMed Central

    Ahn, Ki-Jin; Lee, Younghee; Choi, Hojin; Kim, Min-Sik; Im, Kyungun; Noh, Seonmyeong; Yoon, Hyeonseok

    2015-01-01

    Preparation of conducting-polymer hollow nanoparticles with different diameters was accomplished by surfactant templating. An anionic surfactant, namely sodium dodecylbenzenesulfonate, formed vesicles to template with the pyrrole monomer. Subsequent chemical oxidative polymerization of the monomer yielded spherical polypyrrole (PPy) nanoparticles with hollow interiors. The diameter of the hollow nanoparticles was easily controlled by adjusting the concentration of the surfactant. Subsequently, the size-dependent electrochemical properties of the nanoparticles, including redox properties and charge/discharge behavior, were examined. By virtue of the structural advantages, the specific capacitance (max. 326 F g−1) of PPy hollow nanoparticles was approximately twice as large as that of solid PPy nanospheres. The hollow PPy nanostructure can easily be used as a conductive substrate for the preparation of metal/polymer nanohybrids through chemical and electrochemical deposition. Two different pseudocapacitive metal-oxide clusters were readily deposited on the inner and outer surfaces of the hollow nanoparticles, which resulted in an increase in the specific capacitance to 390 F g−1. In addition, the hollow nanoparticles acted as a nanocage to prevent metal ion leaching during charge/discharge, thus allowing an excellent capacitance retention of ca. 86%, even following 10,000 cycles. PMID:26373685

  1. Image Hashes as Templates for Verification

    SciTech Connect

    Janik, Tadeusz; Jarman, Kenneth D.; Robinson, Sean M.; Seifert, Allen; McDonald, Benjamin S.; White, Timothy A.

    2012-07-17

    Imaging systems can provide measurements that confidently assess characteristics of nuclear weapons and dismantled weapon components, and such assessment will be needed in future verification for arms control. Yet imaging is often viewed as too intrusive, raising concern about the ability to protect sensitive information. In particular, the prospect of using image-based templates for verifying the presence or absence of a warhead, or of the declared configuration of fissile material in storage, may be rejected out-of-hand as being too vulnerable to violation of information barrier (IB) principles. Development of a rigorous approach for generating and comparing reduced-information templates from images, and assessing the security, sensitivity, and robustness of verification using such templates, are needed to address these concerns. We discuss our efforts to develop such a rigorous approach based on a combination of image-feature extraction and encryption-utilizing hash functions to confirm proffered declarations, providing strong classified data security while maintaining high confidence for verification. The proposed work is focused on developing secure, robust, tamper-sensitive and automatic techniques that may enable the comparison of non-sensitive hashed image data outside an IB. It is rooted in research on so-called perceptual hash functions for image comparison, at the interface of signal/image processing, pattern recognition, cryptography, and information theory. Such perceptual or robust image hashing—which, strictly speaking, is not truly cryptographic hashing—has extensive application in content authentication and information retrieval, database search, and security assurance. Applying and extending the principles of perceptual hashing to imaging for arms control, we propose techniques that are sensitive to altering, forging and tampering of the imaged object yet robust and tolerant to content-preserving image distortions and noise. Ensuring that the

  2. Can Ionic Liquids Be Used As Templating Agents For Controlled Design of Uranium-Containing Nanomaterials?

    SciTech Connect

    Visser, A.; Bridges, N.; Tosten, M.

    2013-04-09

    Nanostructured uranium oxides have been prepared in ionic liquids as templating agents. Using the ionic liquids as reaction media for inorganic nanomaterials takes advantage of the pre-organized structure of the ionic liquids which in turn controls the morphology of the inorganic nanomaterials. Variation of ionic liquid cation structure was investigated to determine the impact on the uranium oxide morphologies. For two ionic liquid cations, increasing the alkyl chain length increases the aspect ratio of the resulting nanostructured oxides. Understanding the resulting metal oxide morphologies could enhance fuel stability and design.

  3. Aligned platinum nanowire networks from surface-oriented lipid cubic phase templates

    NASA Astrophysics Data System (ADS)

    Richardson, S. J.; Burton, M. R.; Staniec, P. A.; Nandhakumar, I. S.; Terrill, N. J.; Elliott, J. M.; Squires, A. M.

    2016-01-01

    Mesoporous metal structures featuring a bicontinuous cubic morphology have a wide range of potential applications and novel opto-electronic properties, often orientation-dependent. We describe the production of nanostructured metal films 1-2 microns thick featuring 3D-periodic `single diamond' morphology that show high out-of-plane alignment, with the (111) plane oriented parallel to the substrate. These are produced by electrodeposition of platinum through a lipid cubic phase (QII) template. Further investigation into the mechanism for the orientation revealed the surprising result that the QII template, which is tens of microns thick, is polydomain with no overall orientation. When thicker platinum films are grown, they also show increased orientational disorder. These results suggest that polydomain QII samples display a region of uniaxial orientation at the lipid/substrate interface up to approximately 2.8 +/- 0.3 μm away from the solid surface. Our approach gives previously unavailable information on the arrangement of cubic phases at solid interfaces, which is important for many applications of QII phases. Most significantly, we have produced a previously unreported class of oriented nanomaterial, with potential applications including metamaterials and lithographic masks.Mesoporous metal structures featuring a bicontinuous cubic morphology have a wide range of potential applications and novel opto-electronic properties, often orientation-dependent. We describe the production of nanostructured metal films 1-2 microns thick featuring 3D-periodic `single diamond' morphology that show high out-of-plane alignment, with the (111) plane oriented parallel to the substrate. These are produced by electrodeposition of platinum through a lipid cubic phase (QII) template. Further investigation into the mechanism for the orientation revealed the surprising result that the QII template, which is tens of microns thick, is polydomain with no overall orientation. When thicker

  4. Parallel Synthesis of Poly(amino ether)-Templated Plasmonic Nanoparticles for Transgene Delivery

    PubMed Central

    2015-01-01

    Plasmonic nanoparticles have been increasingly investigated for numerous applications in medicine, sensing, and catalysis. In particular, gold nanoparticles have been investigated for separations, sensing, drug/nucleic acid delivery, and bioimaging. In addition, silver nanoparticles demonstrate antibacterial activity, resulting in potential application in treatments against microbial infections, burns, diabetic skin ulcers, and medical devices. Here, we describe the facile, parallel synthesis of both gold and silver nanoparticles using a small set of poly(amino ethers), or PAEs, derived from linear polyamines, under ambient conditions and in absence of additional reagents. The kinetics of nanoparticle formation were dependent on PAE concentration and chemical composition. In addition, yields were significantly greater in case of PAEs when compared to 25 kDa poly(ethylene imine), which was used as a standard catonic polymer. Ultraviolet radiation enhanced the kinetics and the yield of both gold and silver nanoparticles, likely by means of a coreduction effect. PAE-templated gold nanoparticles demonstrated the ability to deliver plasmid DNA, resulting in transgene expression, in 22Rv1 human prostate cancer and MB49 murine bladder cancer cell lines. Taken together, our results indicate that chemically diverse poly(amino ethers) can be employed for rapidly templating the formation of metal nanoparticles under ambient conditions. The simplicity of synthesis and chemical diversity make PAE-templated nanoparticles useful tools for several applications in biotechnology, including nucleic acid delivery. PMID:25084138

  5. Cooperative Reorganization of Mineral and Template during Directed Nucleation of Calcium Carbonate

    SciTech Connect

    Lee, Jonathan R.; Han, Yong J.; Willey, Trevor M.; Nielsen, Michael H.; Klivansky, Liana M.; Liu, Yi; Chung, Sungwook; Terminello, Louis J.; Van Buuren, Tony W.; De Yoreo, James J.

    2013-04-16

    Self-assembled monolayers (SAMs) prepared from organic thiol molecules on metal substrates are known to exert substantial influence over mineralization and, as such, provide model systems for investigating the mechanisms of templated crystallization by organic matrices. Characterizing the structural evolution at the organic/inorganic interface in SAM/crystal systems is of paramount importance in understanding these mechanisms. In this study, X-ray absorption spectroscopy is used to characterize the structural evolution of SAMs prepared from purpose-synthesized organic thiols, with similar yet subtly different structures and compositions, during the course of mineralization at their surfaces. The studies reveal that the structure of the thiol molecules strongly affects their ability to reorient within the SAM. Complementary scanning electron microscopy measurements demonstrate that the feature of the SAMs is strongly correlated with the capability of the monolayers to induce preferential ordering among the organic crystals. Consistent with recent modeling studies of SAM/crystal systems, these findings provide experimental evidence that structural flexibility within the SAMs is crucial for achieving templated crystallization and that templating is inherently a cooperative process that selects the most favorable combination of SAM and crystal orientations.

  6. 3D template fabrication process for the dual damascene NIL approach

    NASA Astrophysics Data System (ADS)

    Butschke, Joerg; Irmscher, Mathias; Resnick, Douglas; Sailer, Holger; Thompson, Ecron

    2007-05-01

    NIL technique enables an easy replication of three dimensional patterns. Combined with a UV printable low-k material the NIL lithography can dramatically simplify the dual damascene process. Goal of this work was to develop a template process scheme which enables the generation of high resolution pillars on top of corresponding lines for direct printing of later vias and metal lines. The process flow is based on conventional 6025 photomask blanks. Exposure was done on a variable shaped e-beam writer Vistec SB350 using a sample of an advanced negative tone CAR and Fujifilm pCAR FEP171 for the first and the second layer, respectively. Chrome and quartz etching was accomplished in an Oerlikon mask etcher Gen III and Gen IV. Assessment of the developed template process was done in terms of overlay accuracy, feature profile and resolution capability depending on aspect ratio and line duty cycle. Finally the printability of 3D templates fabricated according the developed process scheme was proved.

  7. Condensation of activated diguanylates on a Poly/C/ template. [prebiotic polynucleotide replication mechanism

    NASA Technical Reports Server (NTRS)

    Lohrmann, R.; Bridson, P. K.; Orgel, L. E.

    1981-01-01

    The metal-ion catalysis of the oligomerization of activated diguanylate isomers on a polycytidylic acid template is studied in an investigation of possible early prebiotic polynucleotide replication mechanisms. The 5'-imidazolides of diguanylates linked 2' to 5' or 3' to 5' were reacted with polyC in a 1-methylimidazole or a 2,6-lutidine buffer in the presence of a Zn(+2) or a Pb(+2) catalyst, and reaction products were determined by paper chromatography, paper electrophoresis and liquid chromatography. In the lutidine buffer, the presence of both the Zn(+2) catalyst and the polyC template is found to result in the production of 3'-5' linked oligomers with up to 10 diguanylate units, and from diguanylates in the presence of the monomer. In the reactions conducted in the 1-methylimidazole buffer, the addition of Pb(+2) is found to lead to less marked increases in oligomerization in the presence of template, with approximately equal proportions of 2'-5' and 3'-5' oligomers formed from the 2'-5' substrate and mainly 3'-5' bonds from the 3'-5' linked dimer.

  8. Template-stripped, ultraflat gold surfaces with coplanar, embedded titanium micropatterns.

    PubMed

    Venkataraman, Nagaiyanallur V; Pei, Jia; Cremmel, Clément V M; Rossi, Antonella; Spencer, Nicholas D

    2013-08-01

    Ultraflat gold surfaces with coplanar, embedded titanium micropatterns, exhibiting extremely low roughness over the entire surface, have been obtained by a modified template-stripping procedure. Titanium is deposited onto photolithographically predefined regions of a silicon template. Following photoresist lift-off, the entire surface is backfilled with gold, template stripping is conducted, and an ultraflat micropatterned surface is revealed. Atomic force microscopy confirms a roughness of <0.5 nm RMS on both Ti and Au regions, with a topographically indistinguishable gold-titanium interface. Detailed surface-chemical maps of the patterned surfaces have been obtained by means of imaging X-ray photoelectron spectroscopy (i-XPS) as well as time-of-flight secondary-ion mass spectrometry (ToF-SIMS). They confirm the presence of well-separated Ti and Au regions, with a chemical contrast that is sharp (as determined by ToF-SIMS) and complete (as determined by i-XPS) across the Ti-Au interface. Thus, a surface has been fabricated that is physically homogeneous down to the nanoscale incorporating chemically distinct micropatterns consisting of two different metals, with totally contrasting surface chemistries.

  9. DEXTRON TEMPLATED MICROWAVE-ASSISTED SYNTHESIS OF POROUS TITANIUM DIOXIDE

    EPA Science Inventory

    An alternative route to the preparation and formation of porous titania powders and carbon coated titania using microwave radiation is described. Inexpensive dextrose was chosen as capping agent or template in view of its high water solubility when compared to other sugar templat...

  10. Template-based syntheses for shape controlled nanostructures.

    PubMed

    Pérez-Page, María; Yu, Erick; Li, Jun; Rahman, Masoud; Dryden, Daniel M; Vidu, Ruxandra; Stroeve, Pieter

    2016-08-01

    A variety of nanostructured materials are produced through template-based synthesis methods, including zero-dimensional, one-dimensional, and two-dimensional structures. These span different forms such as nanoparticles, nanowires, nanotubes, nanoflakes, and nanosheets. Many physical characteristics of these materials such as the shape and size can be finely controlled through template selection and as a result, their properties as well. Reviewed here are several examples of these nanomaterials, with emphasis specifically on the templates and synthesis routes used to produce the final nanostructures. In the first section, the templates have been discussed while in the second section, their corresponding synthesis methods have been briefly reviewed, and lastly in the third section, applications of the materials themselves are highlighted. Some examples of the templates frequently encountered are organic structure directing agents, surfactants, polymers, carbon frameworks, colloidal sol-gels, inorganic frameworks, and nanoporous membranes. Synthesis methods that adopt these templates include emulsion-based routes and template-filling approaches, such as self-assembly, electrodeposition, electroless deposition, vapor deposition, and other methods including layer-by-layer and lithography. Template-based synthesized nanomaterials are frequently encountered in select fields such as solar energy, thermoelectric materials, catalysis, biomedical applications, and magnetowetting of surfaces. PMID:27154387

  11. Graphene Emerges as a Versatile Template for Materials Preparation.

    PubMed

    Li, Zhengjie; Wu, Sida; Lv, Wei; Shao, Jiao-Jing; Kang, Feiyu; Yang, Quan-Hong

    2016-05-01

    Graphene and its derivatives are emerging as a class of novel but versatile templates for the controlled preparation and functionalization of materials. In this paper a conceptual review on graphene-based templates is given, highlighting their versatile roles in materials preparation. Graphene is capable of acting as a low-dimensional hard template, where its two-dimensional morphology directs the formation of novel nanostructures. Graphene oxide and other functionalized graphenes are amphiphilic and may be seen as soft templates for formatting the growth or inducing the controlled assembly of nanostructures. In addition, nanospaces in restacked graphene can be used for confining the growth of sheet-like nanostructures, and assemblies of interlinked graphenes can behave either as skeletons for the formation of composite materials or as sacrificial templates for novel materials with a controlled network structure. In summary, flexible graphene and its derivatives together with an increasing number of assembled structures show great potentials as templates for materials production. Many challenges remain, for example precise structural control of such novel templates and the removal of the non-functional remaining templates.

  12. Transdisciplinary Pedagogical Templates and Their Potential for Adaptive Reuse

    ERIC Educational Resources Information Center

    Dobozy, Eva; Dalziel, James

    2016-01-01

    This article explores the use and usefulness of carefully designed transdisciplinary pedagogical templates (TPTs) aligned to different learning theories. The TPTs are based on the Learning Design Framework outlined in the Larnaca Declaration (Dalziel et al. in this collection). The generation of pedagogical plans or templates is not new. However,…

  13. Electrochemical fabrication of graphene nanomesh via colloidal templating.

    PubMed

    Mangadlao, J D; de Leon, A C C; Felipe, M J L; Advincula, R C

    2015-05-01

    A simple electrochemical fabrication of graphene nanomesh (GNM) via colloidal templating is reported for the first time. The process involves the arraying of polystyrene (PS) spheres onto a CVD-deposited graphene, electro-deposition of carbazole units, removal of the PS template and electrochemical oxidative etching. The GNM was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and Raman spectroscopy.

  14. Genetics in Practice: A Template for Interactive Case Studies.

    ERIC Educational Resources Information Center

    Edwards, Erin; Walker, Andy; Bergeson, Kathleen; Louviere, John; Robinson, Kris; Higgins, Joseph; Harris, Charles

    2001-01-01

    Describes the development of a template for interactive case studies that was used for an online continuing medical education course on genetics for health care providers. Discusses goals of the template system, including the production of additional case studies with no additional programming costs and easy updating capabilities. (LRW)

  15. The Applicability of Interactive Item Templates in Varied Knowledge Types

    ERIC Educational Resources Information Center

    Koong, Chorng-Shiuh; Wu, Chi-Ying

    2011-01-01

    A well-edited assessment can enhance student's learning motives. Applicability of items, which includes item content and template, plays a crucial role in authoring a good assessment. Templates in discussion contain not only conventional true & false, multiple choice, completion item and short answer but also of those interactive ones. Methods…

  16. 48 CFR 302.7100 - HHS standard templates and formats.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 4 2013-10-01 2013-10-01 false HHS standard templates and formats. 302.7100 Section 302.7100 Federal Acquisition Regulations System HEALTH AND HUMAN SERVICES GENERAL DEFINITIONS OF WORDS AND TERMS HHS Standard Templates and Formats 302.7100 HHS standard...

  17. 48 CFR 302.7100 - HHS standard templates and formats.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 4 2012-10-01 2012-10-01 false HHS standard templates and formats. 302.7100 Section 302.7100 Federal Acquisition Regulations System HEALTH AND HUMAN SERVICES GENERAL DEFINITIONS OF WORDS AND TERMS HHS Standard Templates and Formats 302.7100 HHS standard...

  18. 48 CFR 302.7100 - HHS standard templates and formats.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 4 2014-10-01 2014-10-01 false HHS standard templates and formats. 302.7100 Section 302.7100 Federal Acquisition Regulations System HEALTH AND HUMAN SERVICES GENERAL DEFINITIONS OF WORDS AND TERMS HHS Standard Templates and Formats 302.7100 HHS standard...

  19. The role of the template in prosthetically guided implantology.

    PubMed

    Annibali, Susanna; La Monaca, Gerardo; Tantardini, Marco; Cristalli, Maria Paola

    2009-02-01

    In prosthetically guided implantology, where ideal placement of implants is determined by the definitive restoration, the use of a radiographic/surgical template plays an essential role. This article describes how to fabricate a radiographic/surgical template to be used for radiographic diagnosis of the selected implant sites and as a guide during surgery for the insertion of the implant with correct angulation.

  20. Component design bases - A template approach

    SciTech Connect

    Pabst, L.F. ); Strickland, K.M. )

    1991-01-01

    A well-documented nuclear plant design basis can enhance plant safety and availability. Older plants, however, often lack historical evidence of the original design intent, particularly for individual components. Most plant documentation describes the actual design (what is) rather than the bounding limits of the design. Without knowledge of these design limits, information from system descriptions and equipment specifications is often interpreted as inviolate design requirements. Such interpretations may lead to unnecessary design conservatism in plant modifications and unnecessary restrictions on plant operation. In 1986, Florida Power and Light Company's (FP and L's) Turkey Point plant embarked on one of the first design basis reconstitution programs in the United States to catalog the true design requirements. As the program developed, design basis users expressed a need for additional information at the component level. This paper outlines a structured (template) approach to develop useful component design basis information (including the WHYs behind the design).