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Sample records for metal alkoxides templates

  1. Metal alkoxides: templates for organometallic chemistry and catalysis. Final technical report on DE FG 02-86ER13570

    SciTech Connect

    Chisholm, Malcolm H.

    2002-11-01

    The physical properties and chemical reactivities of a series of alkoxide, fluoroalkoxide and thiolate compounds of molybdenum and tungsten having M{triple_bond}M or M{triple_bond}N bonds have been examined which reveal the influence of the pi-donor properties of the ligands: RO > R{sub f}O{approx}RS. Single-site metal alkoxide catalysts for the ring-opening polymerization of lactides have been prepared for the metals magnesium, zinc, and aluminum.

  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. 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.

  4. 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

  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. Basic character of rare earth metal alkoxides. Utilization in catalytic C-C bond-forming reactions and catalytic asymmetric nitroaldol reactions

    SciTech Connect

    Sasai, H.; Suzuki, T.; Arai, S.

    1992-05-20

    In a recent paper, the authors reported that Zr(O-t-Bu){sub 4} was an efficient and convenient basic reagent in organic synthesis. However, all reactions examined were performed with stoichiometric quantities of the reagent. The authors envisioned that rare earth metal alkoxides would be stronger bases than group 4 metal alkoxides due to the lower ionization potential (ca. 5.4-6.4 eV) and the lower electronegativity (1.1-1.3) of rare earth elements; thus, the catalytic use of rare earth metal alkoxides in organic synthesis was expected. Although a variety of rare earth metal alkoxides have been prepared for the last three decades, to the authors knowledge, there have been few reports concerning the basicity of rare earth metal alkoxides. Herein, the authors report several carbon-carbon bond-forming reactions catalyzed by rare earth metal alkoxides and their application to a catalytic asymmetric nitroaldol reaction.

  7. 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.

  8. Synthesis of inorganic-organic hybrids from metal alkoxides and silanol-terminated polydimethylsiloxane

    SciTech Connect

    Katayama, Shingo; Yoshinaga, Ikuko; Yamada, Noriko

    1996-12-31

    Inorganic-organic hybrids have been synthesized by reaction of Ti(OC{sub 2}H{sub 5}){sub 4} and Ta(OC{sub 2}H{sub 5}){sub 5} with silanol-terminated polydimethylsiloxane (PDMS). The chemical modification of the metal alkoxides with ethyl acetoacetate (EAcAc) was carried out in order to obtain a transparent and uniform hybrid. The hydrolysis behavior of Ti(OC{sub 2}H{sub 5}){sub 4} modified with EAcAc in the presence of PDMS and the formation of the Ti-O-Si bond in a Ti-O-PDMS hybrid were revealed by FT-IR experiments. Dynamic mechanical measurements showed that a Ta-O-PDMS hybrid was harder than a Ti-O-PDMS hybrid, indicating the effect of metal on the storage modulus of hybrids.

  9. Alkoxide-based precursors for direct drawing of metal oxide micro- and nanofibres

    PubMed Central

    Tätte, Tanel; Hussainov, Medhat; Paalo, Madis; Part, Marko; Talviste, Rasmus; Kiisk, Valter; Mändar, Hugo; Põhako, Kaija; Pehk, Tõnis; Reivelt, Kaido; Natali, Marco; Gurauskis, Jonas; Lõhmus, Ants; Mäeorg, Uno

    2011-01-01

    The invention of electrospinning has solved the problem of producing micro- and nanoscaled metal oxide fibres in bulk quantities. However, until now no methods have been available for preparing a single nanofibre of a metal oxide. In this work, the direct drawing method was successfully applied to produce metal oxide (SnO2, TiO2, ZrO2, HfO2 and CeO2) fibres with a high aspect ratio (up to 10 000) and a diameter as small as 200 nm. The sol–gel processing includes consumption of precursors obtained from alkoxides by aqueous or non-aqueous polymerization. Shear thinning of the precursors enables pulling a material into a fibre. This rheological behaviour can be explained by sliding of particles owing to external forces. Transmission (propagation) of light along microscaled fibres and their excellent surface morphology suggest that metal oxide nanofibres can be directly drawn from sol precursors for use in integrated photonic systems. PMID:27877403

  10. Alkoxide-based precursors for direct drawing of metal oxide micro- and nanofibres

    NASA Astrophysics Data System (ADS)

    Tätte, Tanel; Hussainov, Medhat; Paalo, Madis; Part, Marko; Talviste, Rasmus; Kiisk, Valter; Mändar, Hugo; Põhako, Kaija; Pehk, Tõnis; Reivelt, Kaido; Natali, Marco; Gurauskis, Jonas; Lõhmus, Ants; Mäeorg, Uno

    2011-06-01

    The invention of electrospinning has solved the problem of producing micro- and nanoscaled metal oxide fibres in bulk quantities. However, until now no methods have been available for preparing a single nanofibre of a metal oxide. In this work, the direct drawing method was successfully applied to produce metal oxide (SnO2, TiO2, ZrO2, HfO2 and CeO2) fibres with a high aspect ratio (up to 10 000) and a diameter as small as 200 nm. The sol-gel processing includes consumption of precursors obtained from alkoxides by aqueous or non-aqueous polymerization. Shear thinning of the precursors enables pulling a material into a fibre. This rheological behaviour can be explained by sliding of particles owing to external forces. Transmission (propagation) of light along microscaled fibres and their excellent surface morphology suggest that metal oxide nanofibres can be directly drawn from sol precursors for use in integrated photonic systems.

  11. Hard template synthesis of metal nanowires

    PubMed Central

    Kawamura, Go; Muto, Hiroyuki; Matsuda, Atsunori

    2014-01-01

    Metal nanowires (NWs) have attracted much attention because of their high electron conductivity, optical transmittance, and tunable magnetic properties. Metal NWs have been synthesized using soft templates such as surface stabilizing molecules and polymers, and hard templates such as anodic aluminum oxide, mesoporous oxide, carbon nanotubes. NWs prepared from hard templates are composites of metals and the oxide/carbon matrix. Thus, selecting appropriate elements can simplify the production of composite devices. The resulting NWs are immobilized and spatially arranged, as dictated by the ordered porous structure of the template. This avoids the NWs from aggregating, which is common for NWs prepared with soft templates in solution. Herein, the hard template synthesis of metal NWs is reviewed, and the resulting structures, properties and potential applications are discussed. PMID:25453031

  12. Growth of highly oriented LiNbO 3 thin films through structure controlled metal alkoxide precursor solution

    NASA Astrophysics Data System (ADS)

    Hirano, Shin-ichi; Takeichi, Yoshikuni; Sakamoto, Wataru; Yogo, Toshinobu

    2002-04-01

    Highly oriented LiNbO 3 thin films have been successfully synthesized by chemical solution deposition through a structure controlled metal-organic precursor. The homogeneous LiNbO 3 precursor solution was prepared by controlling the reaction of metal alkoxides and selecting the ligand for modification. LiNbO 3 thin films with c-axis preferred orientation were directly crystallized on sapphire C substrates from chemical solutions synthesized in this study. The epitaxial relation of LiNbO 3 film to sapphire substrate was found to depend strongly upon the precursor structure modified with β-diketone. 1-Phenyl-1,3-butanedione (PBD) was found to be superior to acetylacetone (acacH) and dibenzoylmethane (DBM) for the crystallization of epitaxial LiNbO 3 films. The results suggested that the existence of a benzene ring in the ligand strongly influenced the degree of orientation of synthesized films.

  13. 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.

  14. 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; ...

    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

  15. Metal templated design of protein interfaces.

    PubMed

    Salgado, Eric N; Ambroggio, Xavier I; Brodin, Jeffrey D; Lewis, Richard A; Kuhlman, Brian; Tezcan, F Akif

    2010-02-02

    Metal coordination is a key structural and functional component of a large fraction of proteins. Given this dual role we considered the possibility that metal coordination may have played a templating role in the early evolution of protein folds and complexes. We describe here a rational design approach, Metal Templated Interface Redesign (MeTIR), that mimics the time course of a hypothetical evolutionary pathway for the formation of stable protein assemblies through an initial metal coordination event. Using a folded monomeric protein, cytochrome cb(562), as a building block we show that its non-self-associating surface can be made self-associating through a minimal number of mutations that enable Zn coordination. The protein interfaces in the resulting Zn-directed, D(2)-symmetrical tetramer are subsequently redesigned, yielding unique protein architectures that self-assemble in the presence or absence of metals. Aside from its evolutionary implications, MeTIR provides a route to engineer de novo protein interfaces and metal coordination environments that can be tuned through the extensive noncovalent bonding interactions in these interfaces.

  16. Recent advances in tailoring the aggregation of heavier alkaline earth metal halides, alkoxides and aryloxides from non-aqueous solvents.

    PubMed

    Fromm, Katharina M

    2006-11-21

    This overview on one of the subjects treated in our group deals with the synthesis and study of low-dimensional polymer and molecular solid state structures formed with alkaline earth metal ions in non-aqueous solvents. We have chosen several synthetic approaches in order to obtain such compounds. The first concept deals with the "cutting out" of structural fragments from a solid state structure of a binary compound, which will be explained with reference to BaI2. Depending on the size and concentration of oxygen donor ligands, used as chemical scissors on BaI2, three-, two-, one- and zero-dimensional derived adducts of BaI2 are obtained, comparable to a structural genealogy tree for BaI2. A second part deals with the supramolecular approach for the synthesis of low dimensional polymeric compounds based on alkaline earth metal iodides, obtained by the combination of metal ion coordination with hydrogen bonding between the cationic complexes and their anions. Certain circumstances allow rules to be established for the prediction of the dimensionality of a given compound, contributing to the fundamental problem of structure prediction in crystal engineering. A third section describes a synthetic approach for generating pure alkaline earth metal cage compounds as well as alkali and alkaline earth mixed metal clusters. A first step deals with different molecular solvated alkaline earth metal iodides which are investigated as a function of the ligand size in non-aqueous solvents. These are then reacted with some alkali metal compound in order to partially or totally eliminate alkali iodide and to form the targeted clusters. These unique structures of ligand stabilized metal halide, hydroxide and/or alkoxide and aryloxide aggregates are of interest as potential precursors for oxide materials and as catalysts. Approaches to two synthetic methods of the latter, sol-gel and (MO)CVD (metal-organic chemical vapour deposition), are investigated with some of our compounds. (D

  17. Surfactant-Templated Mesoporous Metal Oxide Nanowires

    DOE PAGES

    Luo, Hongmei; Lin, Qianglu; Baber, Stacy; ...

    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

  18. 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.

  19. Templated Dry Printing of Conductive Metal Nanoparticles

    NASA Astrophysics Data System (ADS)

    Rolfe, David Alexander

    Printed electronics can lower the cost and increase the ubiquity of electrical components such as batteries, sensors, and telemetry systems. Unfortunately, the advance of printed electronics has been held back by the limited minimum resolution, aspect ratio, and feature fidelity of present printing techniques such as gravure, screen printing and inkjet printing. Templated dry printing offers a solution to these problems by patterning nanoparticle inks into templates before drying. This dissertation shows advancements in two varieties of templated dry nanoprinting. The first, advective micromolding in vapor-permeable templates (AMPT) is a microfluidic approach that uses evaporation-driven mold filling to create submicron features with a 1:1 aspect ratio. We will discuss submicron surface acoustic wave (SAW) resonators made through this process, and the refinement process in the template manufacturing process necessary to make these devices. We also present modeling techniques that can be applied to future AMPT templates. We conclude with a modified templated dry printing that improves throughput and isolated feature patterning by transferring dry-templated features with laser ablation. This method utilizes surface energy-defined templates to pattern features via doctor blade coating. Patterned and dried features can be transferred to a polymer substrate with an Nd:YAG MOPA fiber laser, and printed features can be smaller than the laser beam width.

  20. Investigation of metal hydride nanoparticles templated in metal organic frameworks.

    SciTech Connect

    Jacobs, Benjamin W.; Herberg, Julie L.; Highley, Aaron M.; Grossman, Jeffrey; Wagner, Lucas; Bhakta, Raghu; Peaslee, D.; Allendorf, Mark D.; Liu, X.; Behrens, Richard, Jr.; Majzoub, Eric H.

    2010-11-01

    Hydrogen is proposed as an ideal carrier for storage, transport, and conversion of energy. However, its storage is a key problem in the development of hydrogen economy. Metal hydrides hold promise in effectively storing hydrogen. For this reason, metal hydrides have been the focus of intensive research. The chemical bonds in light metal hydrides are predominantly covalent, polar covalent or ionic. These bonds are often strong, resulting in high thermodynamic stability and low equilibrium hydrogen pressures. In addition, the directionality of the covalent/ionic bonds in these systems leads to large activation barriers for atomic motion, resulting in slow hydrogen sorption kinetics and limited reversibility. One method for enhancing reaction kinetics is to reduce the size of the metal hydrides to nano scale. This method exploits the short diffusion distances and constrained environment that exist in nanoscale hydride materials. In order to reduce the particle size of metal hydrides, mechanical ball milling is widely used. However, microscopic mechanisms responsible for the changes in kinetics resulting from ball milling are still being investigated. The objective of this work is to use metal organic frameworks (MOFs) as templates for the synthesis of nano-scale NaAlH4 particles, to measure the H2 desorption kinetics and thermodynamics, and to determine quantitative differences from corresponding bulk properties. Metal-organic frameworks (MOFs) offer an attractive alternative to traditional scaffolds because their ordered crystalline lattice provides a highly controlled and understandable environment. The present work demonstrates that MOFs are stable hosts for metal hydrides and their reactive precursors and that they can be used as templates to form metal hydride nanoclusters on the scale of their pores (1-2 nm). We find that using the MOF HKUST-1 as template, NaAlH4 nanoclusters as small as 8 formula units can be synthesized inside the pores. A detailed picture of

  1. Templated synthesis of metal nanorods in silica nanotubes.

    PubMed

    Gao, Chuanbo; Zhang, Qiao; Lu, Zhenda; Yin, Yadong

    2011-12-14

    We report a general method for the synthesis of noble metal nanorods, including Au, Ag, Pt, and Pd, based on their seeded growth in silica nanotube templates. The controlled growth of the metals occurs exclusively on the seeds inside the silica nanotubes, which act as hard templates to confine the one-dimensional growth of the metal nanorods and define their aspect ratios. This method affords large quantities of noble metal nanorods with well-controlled aspect ratios and high yield, which may find wide use in the fields of nanophotonics, catalysis, sensing, imaging, and biomedicine.

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

    SciTech Connect

    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 [Y2Li33-ONep)(μ3-HONep)(μ-ONep)5(ONep)3(HONep)2] (1), [YNa23-ONep)4(ONep)]2 (2), {[Y2K33-ONep)3(μ-ONep)4(ONep)2(ηξ-tol)2][Y4K24-O)(μ3-ONep)8(ONep)4]•ηx-tol]} (3), [Y4K24-O)(μ3-ONep)8(ONep)4] (3a), [Y2Rb34-ONep)3(μ-ONep)6] (4), and [Y2Cs46-O)(μ3-ONep)63-HONep)2(ONep)2x-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 were 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.

  3. 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.

  4. 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

  5. Titanium alkoxide compound

    DOEpatents

    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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Template-stripped asymmetric metallic pyramids for tunable plasmonic nanofocusing.

    PubMed

    Cherukulappurath, Sudhir; Johnson, Timothy W; Lindquist, Nathan C; Oh, Sang-Hyun

    2013-01-01

    We demonstrate a novel scheme for plasmonic nanofocusing with internally illuminated asymmetric metallic pyramidal tips using linearly polarized light. A wafer-scale array of sharp metallic pyramids is fabricated via template stripping with films of different thicknesses on opposing pyramid facets. This structural asymmetry is achieved through a one-step angled metal deposition that does not require any additional lithography processing and when internally illuminated enables the generation of plasmons using a Kretschmann-like coupling method on only one side of the pyramids. Plasmons traveling toward the tip on one side will converge at the apex, forming a nanoscale "hotspot." The asymmetry is necessary for these focusing effects since symmetric pyramids display destructive plasmon interference at the tip. Computer simulations confirm that internal illumination with linearly polarized light at normal incidence on these asymmetric pyramids will focus optical energy into nanoscale volumes. Far-field optical experiments demonstrate large field enhancements as well as angle-dependent spectral tuning of the reradiated light. Because of the low background light levels, wafer-scale fabrication, and a straightforward excitation scheme, these asymmetric pyramidal tips will find applications in near-field optical microscopy and array-based optical trapping.

  12. Metal-organic framework templated synthesis of ultrathin, well-aligned metallic nanowires.

    PubMed

    Volosskiy, Boris; Niwa, Kenta; Chen, Yu; Zhao, Zipeng; Weiss, Nathan O; Zhong, Xing; Ding, Mengning; Lee, Chain; Huang, Yu; Duan, Xiangfeng

    2015-03-24

    With well-defined porous structures and dimensions, metal-organic frameworks (MOFs) can function as versatile templates for the growth of metallic nanostructures with precisely controlled shapes and sizes. Using MOFs as templates, metallic nanostructures can be grown without the need of bulky surfactants and thus preserve their intrinsic surface. Additionally, the high surface area of MOFs can also ensure that the surface of the template metallic nanostructures is readily accessible, which is critical for the proper function of catalysts or sensors. The hybrid metal@MOF structures have been demonstrated to exhibit useful properties not found in either component separately. Here we report the growth of ultrafine metallic nanowires inside one-dimensional MOF pores with well-controlled shape and size. Our study shows that solvent selection plays an important role in controlling precursor loading and the reduction rate inside the MOF pores for the formation of the nanowires. The growth of the well-aligned, ultrathin nanowires was monitored and characterized by transmission electron microscopy, X-ray diffraction, UV-vis spectroscopy, fluorescence studies, and Brunauer-Emmet-Teller surface area analysis.

  13. Preparation of silica stabilized Tobacco mosaic virus templates for the production of metal and layered nanoparticles.

    PubMed

    Royston, Elizabeth S; Brown, Adam D; Harris, Michael T; Culver, James N

    2009-04-15

    The use of biological molecules as templates for the production of metal nanoparticles and wires is often limited by the stability of the bio-template and its affinity for nucleating metal deposition. In this study, Tobacco mosaic virus (TMV) was used as a model bio-template to investigate the use of silica coatings as a means to both enhance template stability and increase its affinity for metal ions. Results indicate that the unmodified TMV particle can function as a template for the growth of thin (<1 nm) silica layers. However, this thin silica shell did not enhance the stability of the template during metal deposition. To increase silica growth on the TMV template, a pretreatment with aniline was used to produce a uniform silica attractive surface. Aniline pretreated templates yielded significant silica layers of >20 nm in thickness. These silica shells conferred a high degree of stability to the TMV particle and promoted the deposition of various metal nanoparticles through conventional silica mineralization chemistries. This process provides a simple and robust method for the layering of inorganics onto a biological template.

  14. 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.

  15. Templated synthesis for highly ordered metal/support nanocomposite materials with catalytic applications

    NASA Astrophysics Data System (ADS)

    Sarkar, Jayashri

    Template synthesis is a powerful method of synthesizing materials with tunable properties. Tailorability of the templates makes it a viable method for high performance material synthesis. Surfactant, polymers and semiconductors have been used as templating tools for a long time. In the present work, we demonstrate the ability to synthesize hexagonally organized porous titania, zirconia and zirconia/titania mixed oxide supports and their respective nanocomposites of Pt from their alkoxide precursors using a highly viscous mixed surfactant template, separating nanoscopic bicontinuous channels of water and isooctane. Oil soluble precursor that eventually forms the support, precipitates at the oil-water interface mimicking the microstructure of the template. Subsequent reduction of Pt precursor in the aqueous nanochannels decorates the surface of the macropore walls with well-separated platinum (Pt) nanoparticles. This technique enables us to synthesize two components in a single template system by utilizing both oil and water phases. The composite formed possess a bimodal pore size distribution with one mean pore size ˜3.5nm (nanopores) and the other in the larger mean pore diameter regions ˜100nm-2mum (macropores), depending on the oxide support. Because of the decreased mass transfer resistance provided by the ordered and interconnected macropores in the support, the Pt/TiO2 nanocomposite exhibits a significantly higher carbon monoxide oxidation efficiency than that obtained with a commercial support that has a 4-fold larger specific surface area (at equivalent Pt loadings). We further demonstrate that simple changes in the post-synthesis processing can improve the properties of the material. Altering the drying technique and calcination temperature result in a substantial improvement in the specific surface area of the support material making them better than or comparable to the commercial support materials. We are able to synthesize materials with very low Pt

  16. 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.

  17. Mechanisms of metal mineralization on virus templates for nanorod synthesis

    NASA Astrophysics Data System (ADS)

    Adigun, Oluwamayowa O.

    Solution synthesis of nanorods is currently an important area of study due to the precision required to engender advantages in a wide range of fields. Viruses provide a template for synthesis in order to form uniform metal nanorods at mild operating conditions, without the use of expensive technology. In recent years, many materials involving the Tobacco mosaic virus (TMV) and its variants have been synthesized in attempts to produce high quality nanomaterials. However, the underlying processes involved in virion mineralization have not been sufficiently studied to allow for directed synthesis. The fundamental study of the hydrothermal synthesis of palladium on biotemplates, which produces uniform, controllable, monodisperse palladium nanorods, is of interest in this thesis. Three different experimental studies are outlined in this thesis. In situ X-ray absorption spectroscopy (XAS) was employed in order to characterize the reduction and growth mechanisms of palladium (Pd) on the surface of genetically engineered TMV. XAS, via XANES and EXAFS analysis was combined with TEM to confirm an autocatalytic reduction, mediated by the TMV1Cys surface. This reduction interestingly proceeds via two first order regimes, which result in two linear growth regimes as spherical palladium nanoparticles are formed. Results in this project served as an entryway into fundamentally understanding virus-mediated reduction and the relationship between the underlying reduction and growth processes governing mineralization. Pd biomineralization was further elucidated by reframing it within commonly known molecular processes. These included the individual adsorption, reduction, and nanocrystal growth processes, which simultaneously occur during the hydrothermal synthesis on TMV. The adsorption of precursor and reduction of palladium were decoupled through UV-Vis Spectroscopy and in situ XAS studies. The role of additional cysteine (Cys) residues, ionic strength, and coating density on the

  18. Template-Directed Approach Towards the Realization of Ordered Heterogeneity in Bimetallic Metal-Organic Frameworks.

    PubMed

    Kim, Daeok; Coskun, Ali

    2017-03-29

    Controlling the arrangement of different metal ions to achieve ordered heterogeneity in metal-organic frameworks (MOFs) has been a great challenge. Herein, we introduce a template-directed approach, in which a 1D metal-organic polymer incorporating well-defined binding pockets for the secondary metal ions used as a structural template and starting material for the preparation of well-ordered bimetallic MOF-74s under heterogeneous-phase hydrothermal reaction conditions in the presence of secondary metal ions such as Ni(2+) and Mg(2+) in 3 h. The resulting bimetallic MOF-74s were found to possess a nearly 1:1 metal ratio regardless of their initial stoichiometry in the reaction mixture, thus demonstrating the possibility of controlling the arrangement of metal ions within the secondary building blocks in MOFs to tune their intrinsic properties such as gas affinity.

  19. 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

    2013-10-09

    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.

  20. 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

  1. Single crystalline hollow metal-organic frameworks: a metal-organic polyhedron single crystal as a sacrificial template.

    PubMed

    Kim, Hyehyun; Oh, Minhak; Kim, Dongwook; Park, Jeongin; Seong, Junmo; Kwak, Sang Kyu; Lah, Myoung Soo

    2015-02-28

    Single crystalline hollow metal-organic frameworks (MOFs) with cavity dimensions on the order of several micrometers and hundreds of micrometers were prepared using a metal-organic polyhedron single crystal as a sacrificial hard template. The hollow nature of the MOF crystal was confirmed by scanning electron microscopy of the crystal sliced using a focused ion beam.

  2. Replicative generation of metal microstructures by template-directed electrometallization

    SciTech Connect

    Thom, I.; Haehner, G.; Buck, M.

    2005-07-11

    Copper structures were produced by electrochemical deposition onto patterned self-assembled monolayers (SAMS) of thiols adsorbed on polycrystalline gold substrates and subsequent transfer to an insulating substrate. Selective metal deposition was achieved by use of thiols which differ in their electrochemical blocking properties, namely hexadecane thiol [CH{sub 3}(CH{sub 2}){sub 15}SH] and {omega}-(4{sup '}-methyl-biphenyl-4-yl)-methanethiol (CH{sub 3}-C{sub 6}H{sub 4}-C{sub 6}H{sub 4}-CH{sub 2}-SH). Besides control of the blocking properties, the SAM served to minimize adhesion between the metal deposit and the substrate, thus, allowing the transfer of the metal pattern. Since the process is replicative, it represents a very simple and fast route to generating metal patterns.

  3. Replicative generation of metal microstructures by template-directed electrometallization

    NASA Astrophysics Data System (ADS)

    Thom, I.; Hähner, G.; Buck, M.

    2005-07-01

    Copper structures were produced by electrochemical deposition onto patterned self-assembled monolayers (SAMS) of thiols adsorbed on polycrystalline gold substrates and subsequent transfer to an insulating substrate. Selective metal deposition was achieved by use of thiols which differ in their electrochemical blocking properties, namely hexadecane thiol [CH3(CH2)15SH] and ω-(4'-methyl-biphenyl-4-yl)-methanethiol (CH3-C6H4-C6H4-CH2-SH). Besides control of the blocking properties, the SAM served to minimize adhesion between the metal deposit and the substrate, thus, allowing the transfer of the metal pattern. Since the process is replicative, it represents a very simple and fast route to generating metal patterns.

  4. Enantiopure anion templated synthesis of a zeolitic metal-organic framework.

    PubMed

    Xu, Zhong-Xuan; Ma, Yu-Lu; Zhang, Jian

    2016-01-31

    Utilizing (R)-H3CIA as a chiral template, an unprecedented homochiral metal-organic framework (MOF) with zeotype GIS topology is obtained from achiral 1.4-DIB ligands and Zn(II) ions, which opens up a feasible approach to create zeolitic MOFs with homochirality.

  5. Oxidation sharpening, template stripping, and passivation of ultra-sharp metallic pyramids and wedges.

    PubMed

    Im, Hyungsoon; Oh, Sang-Hyun

    2014-02-26

    Ultra-sharp metallic pyramids and wedges with tunable tip angles and 5-nm tip radii are replicated from oxidation-sharpened silicon templates with high throughput (80 million pyramids per wafer). Atomic layer deposition of Al2 O3 shells can protect these sharp pyramidal tips for subsequent usage in near-field imaging.

  6. Metal-organic framework templated synthesis of porous inorganic materials as novel sorbents

    DOEpatents

    Taylor-Pashow, Kathryn M. L.; Lin, Wenbin; Abney, Carter W.

    2017-03-21

    A novel metal-organic framework (MOF) templated process for the synthesis of highly porous inorganic sorbents for removing radionuclides, actinides, and heavy metals is disclosed. The highly porous nature of the MOFs leads to highly porous inorganic sorbents (such as oxides, phosphates, sulfides, etc) with accessible surface binding sites that are suitable for removing radionuclides from high level nuclear wastes, extracting uranium from acid mine drainage and seawater, and sequestering heavy metals from waste streams. In some cases, MOFs can be directly used for removing these metal ions as MOFs are converted to highly porous inorganic sorbents in situ.

  7. Metal-silicate catalysts: Single site, mesoporous systems without templates

    SciTech Connect

    Barnes, Craig E.; Sharp, Katherine; Albert, Austin A; Abbott, Joshua; Peretich, Michael E; Fulvio, Pasquale; Ciesielski, Peter N.; Donohoe, Bryon S.

    2015-06-01

    The textural properties of a family of silicate and mixed metal-silicate materials prepared by a nonaqueous sol-gel reaction involving the cubic silicate Si8O20(SnMe3)8 and metal chlorides MCl4 (M = Si, Ti, Zr) cross-linking reagents are described. Nitrogen adsorption isotherm data is presented and surface area and pore size distribution analyses for several examples of these materials are developed and correlated with the ratio of cross-linking reagent and the cubic silicate building block at the time of synthesis. Significant surface area and pore size distributions that shift to higher pore diameters are observed as the ratio of cross-linking reagent-to-cubic building block increases. A simple strategy for simultaneously controlling the porosity of these matrices while homogeneously dispersing identical metal centers on their surfaces for next generation catalysts is described.

  8. Engineering Hybrid Metallic Nanostructures Using a Single Domain of Block Copolymer Templates.

    PubMed

    Liu, Zhicheng; Chang, Tongxin; Huang, Haiying; He, Tianbai

    2015-11-25

    Building complex nanostructures using a simple patterned template is challenging in material science and nanotechnology. In the present work, three different strategies have been exploited for the successful fabrication of hybrid dots-on-wire metallic nanostructures through combining an in-situ method with an ex-situ method. Basically, plasma etching was applied to generate a metallic wire-like nanostructure, and preformed nanoparticles could be placed through multiple means before or after the formation of the wire-like nanostructure. Various monometallic and bimetallic nanostructures have been obtained by utilizing only one functional domain of block copolymer templates. In these cases, full utilization of the functional domain or introduction of the molecular linker is critical to engineering hybrid metallic nanostructures. Other complex and multifunctional hybrid nanostructures can be developed via these strategies similarly, and these nanostructures are promising for useful applications such as optics and surface-enhanced Raman spectroscopy (SERS).

  9. 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

  10. 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.

  11. Synthesis of ternary metal nitride nanoparticles using mesoporous carbon nitride as reactive template.

    PubMed

    Fischer, Anna; Müller, Jens Oliver; Antonietti, Markus; Thomas, Arne

    2008-12-23

    Mesoporous graphitic carbon nitride was used as both a nanoreactor and a reactant for the synthesis of ternary metal nitride nanoparticles. By infiltration of a mixture of two metal precursors into mesoporous carbon nitride, the pores act first as a nanoconfinement, generating amorphous mixed oxide nanoparticles. During heating and decomposition, the carbon nitride second acts as reactant or, more precisely, as a nitrogen source, which converts the preformed mixed oxide nanoparticles into the corresponding nitride (reactive templating). Using this approach, ternary metal nitride particles with diameters smaller 10 nm composed of aluminum gallium nitride (Al-Ga-N) and titanium vanadium nitride (Ti-V-N) were synthesized. Due to the confinement effect of the carbon nitride matrix, the composition of the resulting metal nitride can be easily adjusted by changing the concentration of the preceding precursor solution. Thus, ternary metal nitride nanoparticles with continuously adjustable metal composition can be produced.

  12. Structure of reverse microemulsion-templated metal hexacyanoferrate nanoparticles

    PubMed Central

    2012-01-01

    The droplet phase of a reverse microemulsion formed by the surfactant cetyltrimethylammonium ferrocyanide was used as a matrix to synthesize nanoparticles of nickel hexacyanoferrate by adding just a solution of NiCl2 to the microemulsion media. Dynamic light scattering and small-angle neutron scattering measurements show that the reverse microemulsion droplets employed have a globular structure, with sizes that depend on water content. Transmission electron microscopy and electron diffraction are used to obtain information about the structure of the synthesized nanoparticles. The results show that the size and shape of the coordination compound nanoparticles correspond with the size and shape of the droplets, suggesting that the presented system constitutes an alternative method of the synthesis of metal hexacyanoferrate nanoparticles. PMID:22264404

  13. Plate, wire, mesh, microsphere, and microtube composed of sodium titanate nanotubes on a titanium metal template.

    PubMed

    Yada, Mitsunori; Inoue, Yuko; Uota, Masafumi; Torikai, Toshio; Watari, Takanori; Noda, Iwao; Hotokebuchi, Takao

    2007-02-27

    Sodium titanate nanotube/titanium metal composites were synthesized by hydrothermal treatment of titanium metals with various morphologies such as plate, wire, mesh, microsphere, and microtube at 160 degrees C in aqueous NaOH solution and by the subsequent fixation treatment by calcination at 300 degrees C. The surface of the composite was covered with sodium titanate nanotubes with a diameter of approximately 7 nm, and the core part of the composite was titanium metal phase. The raw titanium metal acts as a template or a morphology-directing agent of micrometer size or more to arrange the nanotubes as well as a titanium source for the formation of nanotubes. The concentration of titanium species increases in the reaction solution as the dissolution of titanium metal is accelerated by the reaction between titanium and OH-. Furthermore, with an increase in concentration of titanium species in the reaction solution, the titanium species are re-precipitated as sodium titanate nanotubes onto the titanium metal. Titanium metal with a large surface area and volume can form sodium titanate nanotubes on the surface of the titanium metal, though titanium metal with a small volume and surface area tends to dissolve with the hydrothermal treatment. Even in the synthesis using titanium metal with a small volume and surface area, sodium titanate nanotubes are formed and cover the surface of the titanium metal by adding another titanium metal as a source of titanium species in the reaction solution.

  14. 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.

  15. Template Synthesis of Noble Metal Nanocrystals with Unusual Crystal Structures and Their Catalytic Applications.

    PubMed

    Fan, Zhanxi; Zhang, Hua

    2016-12-20

    Noble metal nanocrystals own high chemical stability, unique plasmonic and distinctive catalytic properties, making them outstanding in many applications. However, their practical applications are limited by their high cost and scarcity on the earth. One promising strategy to solve these problems is to boost their catalytic performance in order to reduce their usage amount. To realize this target, great research efforts have been devoted to the size-, composition-, shape- and/or architecture-controlled syntheses of noble metal nanocrystals during the past two decades. Impressively, recent experimental studies have revealed that the crystal structure of noble metal nanocrystals can also significantly affect their physicochemical properties, such as optical, magnetic, catalytic, mechanical, electrical and electronic properties. Therefore, besides the well-established size, composition, shape, and architecture control, the rise of crystal structure-controlled synthesis of noble metal nanocrystals will open up new opportunities to further improve their functional properties, and thus promote their potential applications in energy conversion, catalysis, biosensing, information storage, surface enhanced Raman scattering, waveguide, near-infrared photothermal therapy, controlled release, bioimaging, biomedicine, and so on. In this Account, we review the recent research progress on the crystal structure control of noble metal nanocrystals with a template synthetic approach and their crystal structure-dependent catalytic properties. We first describe the template synthetic methods, such as epitaxial growth and galvanic replacement reaction methods, in which a presynthesized noble metal nanocrystal with either new or common crystal structure is used as the template to direct the growth of unusual crystal structures of other noble metals. Significantly, the template synthetic strategy described here provides an efficient, simple and straightforward way to synthesize unusual

  16. 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.

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

    PubMed

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

    2016-05-23

    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.

  18. AlGaN Metal-Semiconductor-Metal Photodetectors on Planar and Epitaxial Laterally Overgrown AlN/Sapphire Templates for the Ultraviolet C Spectral Region

    NASA Astrophysics Data System (ADS)

    Knigge, Andrea; Brendel, Moritz; Brunner, Frank; Einfeldt, Sven; Knauer, Arne; Kueller, Viola; Zeimer, Ute; Weyers, Markus

    2013-08-01

    Schottky type metal-semiconductor-metal (MSM) Al0.4Ga0.6N photodetectors (PDs) for the ultraviolet C spectral region on conventional planar AlN templates are compared with epitaxial laterally overgrown (ELO) AlN templates. On planar templates solar blind MSM PDs with state-of-the-art dark current in the pA range and a power independent responsivity are obtained. PDs on ELO templates with fingers parallel to the etched stripes have properties similar to those on planar templates. PDs on ELO templates with contact fingers oriented perpendicular to the etched stripe pattern exhibit photoconductive gain leading to external quantum efficiencies of up to 77 at 30 V applied bias surpassing that of the planar grown PDs by a factor of 100. In spite of the high gain these PDs also show low dark currents, short switching times and two operating regimes with power independent responsivity.

  19. Preparation of metallic pivot-based imprinted monolith for polar template.

    PubMed

    Zhong, Dan-Dan; Huang, Yan-Ping; Xin, Xue-Lei; Liu, Zhao-Sheng; Aisa, Haji Akber

    2013-09-01

    One of the main challenges in MIPs preparation is the proper MIP monolith design for water-soluble compounds due to the difficulty in satisfying the demands of both good column permeability and affinity to polar template. A new strategy of metallic pivot in a ternary porogenic system of dimethyl sulfoxide (DMSO)-dimethylformamide (DMF)-1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4) was suggested to solve this problem. An imprinted monolithic column with high porosity and good permeability was synthesized using a mixture of methyl gallate (template), 4-vinylpyridine, ethylene glycol dimethacrylate, and cobalt acetate. Some polymerization factors, such as template-monomer molar ratio and the composition of the ionic liquid, on the imprinting effect of the resulting MIPs monoliths were systematically investigated. In a mobile phase of acetonitrile-buffer, the greatest imprinting factor of 10.9 was obtained on the MIPs monolith with the optimized polymerization parameters. Thermodynamic analysis for separation demonstrated that the separation between the template and its analogs on the ion-mediated MIPs monolith is an enthalpy-controlled process.

  20. 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.

  1. Spectrophotometric titration of bimetallic metal cation binding in polyamido(amine) dendrimer templates.

    PubMed

    Marvin, Katherine A; Johnson, Justin A; Rodenbusch, Stacia E; Gong, Lucy; Vanden Bout, David A; Stevenson, Keith J

    2012-06-05

    Spectrophotometric titration and a binding isotherm were used to accurately assess the loading capacity of generation four polyamido(amine) (PAMAM) dendrimer templates with terminal alcohol groups (G4-OH). Preparation of bimetallic G4-OH dendrimer-encapsulated metal nanoclusters (DENs) necessitates knowledge of the precise metal-ion binding capacity. The binding of metal ions such as Pt(2+) and Pd(2+) has proven difficult to assess via UV-vis spectroscopy because the absorbance shifts associated with metal-ion binding within the dendrimer template are masked by the absorbance of the PAMAM dendrimer itself. In contrast, the binding of Cu(2+) to G4-OH PAMAM dendrimer results in a strong, distinct absorption band at 300 nm, making UV-vis spectrophotometric titration with copper straightforward. Here we use copper binding as a means to assess the number of binding sites remaining within the PAMAM G4-OH dendrimer after the complexation of a specified molar excess of Pd(2+) or Pt(2+). In addition, we use a binding isotherm to mathematically estimate the loading capacity of the dendrimer in each case. The loading capacities for M(2+) in the G4-OH dendrimer were found to be ∼16 for copper alone, ∼21 for copper combined with palladium, and ∼25 for copper combined with platinum.

  2. Mesoporous mixed metal oxides derived from P123-templated Mg-Al layered double hydroxides

    SciTech Connect

    Wang Jun; Zhou Jideng; Li Zhanshuang; He Yang; Lin Shuangshuang; Liu Qi; Zhang Milin; Jiang Zhaohua

    2010-11-15

    We report the preparation of mesoporous mixed metal oxides (MMOs) through a soft template method. Different amounts of P123 were used as structure directing agent to synthesize P123-templated Mg-Al layered double hydroxides (LDHs). After calcination of as-synthesized LDHs at 500 {sup o}C, the ordered mesopores were obtained by removal of P123. The mesoporous Mg-Al MMOs fabricated by using 2 wt% P123 exhibited a high specific surface area of 108.1 m{sup 2}/g, and wide distribution of pore size (2-18 nm). An investigation of the 'memory effect' of the mesoporous MMOs revealed that they were successfully reconstructed to ibuprofen intercalated LDHs having different gallery heights, which indicated different intercalation capacities. Due to their mesoporosity these unique MMOs have particular potential as drug or catalyst carriers. - Graphical abstract: Ordered mesoporous Mg-Al MMOs can be obtained through the calcination of P123-templated Mg-Al-CO{sub 3} LDHs. The pore diameter is 2.2 nm. At the presence of ibuprofen, the Mg-Al MMOs can recover to Mg-Al-IBU LDHs, based on its 'remember effect'. Display Omitted

  3. Effects of Metal Composition and Ratio on Peptide-Templated Multimetallic PdPt Nanomaterials.

    PubMed

    Merrill, Nicholas A; Nitka, Tadeusz T; McKee, Erik M; Merino, Kyle C; Drummy, Lawrence F; Lee, Sungsik; Reinhart, Benjamin; Ren, Yang; Munro, Catherine J; Pylypenko, Svitlana; Frenkel, Anatoly I; Bedford, Nicholas M; Knecht, Marc R

    2017-03-08

    It can be difficult to simultaneously control the size, composition, and morphology of metal nanomaterials under benign aqueous conditions. For this, bioinspired approaches have become increasingly popular due to their ability to stabilize a wide array of metal catalysts under ambient conditions. In this regard, we used the R5 peptide as a three-dimensional template for formation of PdPt bimetallic nanomaterials. Monometallic Pd and Pt nanomaterials have been shown to be highly reactive toward a variety of catalytic processes, but by forming bimetallic species, increased catalytic activity may be realized. The optimal metal-to-metal ratio was determined by varying the Pd:Pt ratio to obtain the largest increase in catalytic activity. To better understand the morphology and the local atomic structure of the materials, the bimetallic PdPt nanomaterials were extensively studied by transmission electron microscopy, extended X-ray absorption fine structure spectroscopy, X-ray photoelectron spectroscopy, and pair distribution function analysis. The resulting PdPt materials were determined to form multicomponent nanostructures where the Pt component demonstrated varying degrees of oxidation based upon the Pd:Pt ratio. To test the catalytic reactivity of the materials, olefin hydrogenation was conducted, which indicated a slight catalytic enhancement for the multicomponent materials. These results suggest a strong correlation between the metal ratio and the stabilizing biotemplate in controlling the final materials morphology, composition, and the interactions between the two metal species.

  4. A cracked polymer templated metal network as a transparent conducting electrode for ITO-free organic solar cells.

    PubMed

    Rao, K D M; Hunger, Christoph; Gupta, Ritu; Kulkarni, Giridhar U; Thelakkat, Mukundan

    2014-08-07

    We report a highly transparent, low resistance Ag metal network templated by a cracked polymer thin film and its incorporation in an organic solar cell. The performance of this scalable metallic network is comparable to that of conventional ITO electrodes. This is a general approach to replace ITO in diverse thin film devices.

  5. 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

  6. Alkoxide activation of aminoboranes towards selective amination.

    PubMed

    Solé, Cristina; Fernández, Elena

    2013-10-18

    Piece of the (inter)action: The interaction of alkoxides with the sp(2) Bpin (pin=pinacol) moiety in aminoboranes forms the in situ Lewis acid-base adduct [RO(-) →B(OR)2 N(R')2 ] which enables the amino moiety to react as a strong nucleophile with several electrophiles, thus providing amino alcohols, β-enamino esters, and β-hydroxy amides in a direct and remarkably selective way.

  7. 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

  8. 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.

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

    NASA Astrophysics Data System (ADS)

    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

    2014-05-01

    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.

  10. Five discrete multinuclear metal-organic assemblies from one ligand: deciphering the effects of different templates.

    PubMed

    Riddell, Imogen A; Hristova, Yana R; Clegg, Jack K; Wood, Christopher S; Breiner, Boris; Nitschke, Jonathan R

    2013-02-20

    A rigid organic ligand, formed through the subcomponent self-assembly of p-toluidine and 6,6'-diformyl-3,3'-bipyridine, was employed in a systematic investigation into the synergistic and competing effects of metal and anion templation. A range of discrete and polymeric metal-organic complexes were formed, many of which represent structure types that have not previously been observed and whose formation would not be predicted on taking into account solely geometric considerations. These complex structures, capable of binding multiple guests within individual binding pockets, were characterized by NMR, ESI-MS, and single-crystal X-ray diffraction. The factors that stabilize individual complexes and lead to the formation of one over another are discussed.

  11. Formation of Periodic 2D Metallic Nanostructures by Template-Assisted Electrodeposition

    NASA Astrophysics Data System (ADS)

    Wang, Mu; Zhang, Bo; Weng, Yuyan; Peng, Ruwen; Ming, Naiben

    2008-03-01

    Two-dimensional ordered metallic nanostructures on solid surface with specific patterns may have potential applications in photonics and optoelectronics. Yet it remains a challenge to produce regular nanostructures over a large area with low cost and with a simple method. Here we report a novel method to fabricate well-aligned copper nanowire array on silicon surface by template-assisted electrodeposition. The template is introduced onto silicon surface by nanoimprinting. With our previously reported unique electrodeposition system [1-2], we find that the array of straight copper wires with their width varying from 400 nm to 20 nm can be fabricated. The wire width can be tuned by the control parameters in electrodeposition. It is shown that this method is not limited to straight wires only. It can be used to form more complicated patterns. The physical properties of the metallic nanostructures are also discussed. [1] M. Zhang, S. Lenhert, M. Wang, L. Chi, et al., Adv. Mater. 16, 409 (2004) [2] M. Wang, S. Zhong, X. Yin, J. Zhu, et al., Phys. Rev. Lett., 86, 3827 (2001)

  12. Metal-Organic Frameworks As Templates for Nanoscale NaAlH 4

    SciTech Connect

    Bhakta, Raghunandan K.; Herberg, Julie L.; Jacobs, Benjamin; Highley, Aaron; Behrens, Richard; Ockwig, Nathan W.; Greathouse, Jeffery A.; Allendorf, Mark D.

    2009-09-01

    Metal-organic frameworks (MOFs) offer an attractive alternative to traditional hard and soft templates for nanocluster synthesis because their ordered crystalline lattice provides a highly controlled and inherently understandable environment. We demonstrate that MOFs are stable hosts for metal hydrides proposed for hydrogen storage and their reactive precursors, providing platform to test recent theoretical predictions that some of these materials can be destabilized with respect to hydrogen desorption by reducing their critical dimension to the nanoscale. With the MOF HKUST-1 as template, we show that NaAlH4 nanoclusters as small as eight formula units can be synthesized. The confinement of these clusters within the MOF pores dramatically accelerates the desorption kinetics, causing decomposition to occur at ~100 °C lower than bulk NaAlH4. However, using simultaneous thermogravimetric modulated beam mass spectrometry, we also show that the thermal decomposition mechanism of NaAlH4 is complex and may involve processes such as nucleation and growth in addition to the normally assumed two-step chemical decomposition reactions.

  13. Controlled DNA-templated metal deposition: towards ultra-thin nanowires.

    PubMed

    Berti, Lorenzo; Alessandrini, Andrea; Menozzi, Claudia; Facci, Paolo

    2006-08-01

    In this paper, we report the metallization of a dsDNA template using a novel photography-derived two-step strategy in which dsDNA is first complexed with Ag(I) ions and then irradiated with UV light at 254 nm. The nucleobases act as light harvesters and sensitizers, triggering the photoreduction of the complexed silver ions. This process yields a silver nanoparticles blueprint along the DNA strand. The silver latent image is then developed by depositing metallic nickel through an electroless plating process. This photography-derived procedure generates very homogeneous and evenly distributed strings of silver-core/nickel-shell nanoparticles. Although still discontinuous, we believe that such chains can serve as the base for obtaining continuous metal nanowires. Furthermore, this process can most likely be extended to other plating metals, resulting in a broadly general procedure for metallizing DNA with a variety of different materials. Because of the intrinsic simplicity in using light as the key step, this methodology might be amenable to large-scale development, eventually leading to a very efficient molecular-photolithography process.

  14. Manufacturing carbon nanofiber electrodes with embedded metallic nanoparticles using block copolymers templates

    NASA Astrophysics Data System (ADS)

    Ghazinejad, Maziar; Holmberg, Sunshine; Madou, Marc

    2016-09-01

    Owing to its superb thermal and electrical attributes, as well as electrochemical stability, carbon is emerging as an attractive material for fabrication of many bioelectrochemical devices such as biosensors and biofuel cells. However, carbon's inert nature makes it difficult to functionalize with biocatalysts; often requiring harsh chemical treatment, such as nitric acid oxidation, to attach reactive amines and carboxylic acids to its surface. Recent studies, however, points toward a self-assembly approach for fabricating well organized layers of carbon loaded with arrays of metallic nanoparticles patterned by block-copolymers (BCP) templates. Herein, we demonstrate an effective method for developing carbon nanofibers meshes embedded with metal nanoparticles, by incorporating a BCP self-assembly approach into our C-MEMS fabrication technique. The main phase of this hybrid method includes electrospinning metal salt-loaded BCP into nanofiber meshes, and subsequently reducing the metal salts into metal nanoparticles prior to pyrolysis. This cost-effective process will pave the way for fabricating scalable advanced 3-D carbon electrodes that can be applied to biosensors and biofuel cells devices.

  15. 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.

  16. Water-soluble titanium alkoxide material

    DOEpatents

    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.

  17. Metal-organic framework templated synthesis of Fe2O3/TiO2 nanocomposite for hydrogen production.

    PubMed

    deKrafft, Kathryn E; Wang, Cheng; Lin, Wenbin

    2012-04-17

    A new metal-organic framework (MOF)-templated method has been developed for the synthesis of a metal oxide nanocomposite with interesting photophysical properties. Fe-containing nanoscale MOFs are coated with amorphous titania, then calcined to produce crystalline Fe(2)O(3)/TiO(2) composite nanoparticles. This material enables photocatalytic hydrogen production from water using visible light, which cannot be achieved by either Fe(2)O(3) or TiO(2) alone or a mixture of the two.

  18. 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

  19. 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

  20. 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.

  1. Simultaneous immunoassay of phosphorylated proteins based on apoferritin templated metallic phosphates as voltammetrically distinguishable signal reporters.

    PubMed

    Ge, Xiaoxiao; Zhang, Aidong; Lin, Yuehe; Du, Dan

    2016-06-15

    A novel electrochemical immunosensor has been developed to detect phosphorylated proteins, phospho-p53(15) and phospho-p53(392), simultaneously. Different apoferritin templated metal phosphates were used as distinguishable signal reporters (apoferritin templated cadmium phosphates (ATCP) and apoferritin templated lead phosphates (ATLP)) to enhance the detection sensitivity. Here, magnetic Fe3O4 nanoparticles functionalized phospho-p53(15) capture antibody (MP-p53(15)c-Ab) and phospho-p53(392) capture antibody (MP-p53(392)c-Ab), respectively, were used to specifically capture phospho-p53(15) and phospho-p53(392) antigens, followed by immunorecognition with p53(15) detection antibody (p53(15)d-Ab) and p53(392) detection antibody (p53(392)d-Ab) to form sandwich-like immunocomplexes. SiO2@Au nanocomposites served as nanocarriers for co-immobilization of both d-Ab and signal reporters (ATCP/SiO2@Au/p53(15)d-Ab, ATLP/SiO2@Au/p53(392)d-Ab), which greatly amplified the detection signal. The distinguished current responses were achieved by electrochemical detection of cadmium ions and lead ions with square wave voltammetry (SWV) after dissolution with acid. The proposed immunoassay exhibited high sensitivity and selectivity for the detection of phospho-p53(15) and phospho-p53(392) simultaneously. The linear relationships between electrochemical responses and the concentrations of phospho-p53(15) and phospho-p53(392) were obtained in the range of 0.1-20 ng/mL and 0.05-20 ng/mL, respectively. The detection limits were 0.05 and 0.02 ng/mL (S/N=3), respectively. This strategy provides a new platform for simultaneous immunoassay of multiple protein biomarkers.

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

    PubMed

    Hsueh, Han-Yu; Ho, Rong-Ming

    2012-06-05

    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.

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

    SciTech Connect

    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.

  4. 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

    2015-10-05

    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.

  5. 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

  6. 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.

  7. Syntheses and crystal structures of three new borates templated by transition-metal complexes in situ

    NASA Astrophysics Data System (ADS)

    Wang, Guo-Ming; Sun, Yan-Qiong; Yang, Guo-Yu

    2006-05-01

    Three new cobalt borate compounds, [Co(DIEN) 2][B 5O 6(OH) 4] 2 (DIEN=diethylenetriamine) ( 1), [B 5O 7(OH) 3Co(TREN)] (TREN= tris(2-aminoethyl)amine) ( 2), and [Co 2(TETA) 3][B 5O 6(OH) 4] 4 (TETA=triethylenetetramine) ( 3) have been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction, IR, elemental analysis and thermogravimetry. The structures exhibit interesting 3D supramolecular hydrogen-bonded architectures, involving the similar borate polyanion [B 5O 6+n(OH) 4-n] ( n+1)- ( n=0 for 1 and 3, and n=1 for 2) and the templating transition metal complexes which are generated in situ under mild solvothermal conditions. Crystal data: 1, monoclinic, space group C2/ m (No. 12), a=15.2372(3) Å, b=11.5987(2) Å, c=8.4163(3) Å, β=93.601(4)°, V=1484.49(7) Å3, Z=2; 2, monoclinic, P2 1/ c (No. 14), a=8.9881(3) Å, b=20.7648(5) Å, c=9.3681(2) Å, β=99.926(4)°, V=1722.25(8) Å3, Z=4; 3, triclinic, space group P-1 (No. 2), a=12.3717(4) Å, b=12.9653(8) Å, c=19.0925(3) Å, α=77.009(5)°, β=80.095(2)°, γ=82.334(3)°, V=2925.3(2) Å3, Z=2.

  8. Zirconium alkoxide interfaces for adhesion enhancement and electrocatalysis

    NASA Astrophysics Data System (ADS)

    Vanderkam, Susan Killian

    Tetra(tert-butoxy)zirconium was chemisorbed onto the native oxide layers of aluminum, iron, copper, and porous silicon, forming surface bound di- or tri-alkoxy zirconium species. Poly(ethylene- co-acrylic acid) was subsequently reacted with the surface forming chemically bound copolymer through carboxyzirconium linkages. Copolymer bound through the zirconium complex adhered to the metal oxide surfaces better than without the zirconium alkoxide intermediate, as determined by FTIR spectroscopy. Copper substrates were subjected to a variety of stability tests, including exposure to ambient conditions, base washing, and chronocoulometry. The copper-zirconium-copolymer ensemble was shown to be very stable in all of these tests. Indium tin oxide (ITO) powder was titrated to determine surface hydroxyl content per unit area. ITO-coated glass slides were reacted with tetra( tert-butoxy)zirconium, and subsequently with both carboxylic acid and phenol derivatives. Ferrocene-carboxyzirconium-coated ITO was characterized electrochemically, and the surface loading of ferrocene was found to be approximately one monolayer. Phenoxyzirconium-coated ITO was also characterized electrochemically and tested for electrocatalytic properties for the oxidation of several compounds in solution. Phenoxyzirconium-coated ITO was found to improve the oxidation kinetics for ferrocene and tetramethylphenylenediamine in acetonitrile.

  9. 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.

  10. 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.

  11. 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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

  13. Lithium bromide-induced structural changes in a nickel bis-alkoxide complex.

    PubMed

    Ichiokai, Hiromi; Vicic, David A

    2013-01-01

    The bis-alkoxide [(DEAMP)2Ni] (1, DEAMP = 1-(diethylamino)-2-methylpropan-2-olate) was found to react with trace amounts of lithium bromide to afford the bis-LiBr adduct 2, in which the oxygens of the DEAMP ligand coordinate to lithium to form a chiral-at-metal complex. This new complex is five-coordinate at nickel, and contains nickel and oxygen atoms which are all chiral. One diastereomer precipitates from pentane solution. The two lithium ions rigidify the new structure in the solid state by coordinating to the oxygen and bromide atoms.

  14. Catalytic reactions of titanium alkoxides with Grignard reagents and imines: a mechanistic study.

    PubMed

    Kumar, Akshai; Samuelson, Ashoka G

    2010-08-02

    The reactivity of Grignard reagents towards imines in the presence of catalytic and stoichiometric amounts of titanium alkoxides is reported. Alkylation, reduction, and coupling of imines take place. Whereas reductive coupling is the major reaction in stoichiometric reactions, alkylation is favored in catalytic reactions. Mechanistic studies clearly indicate that intermediates involved in the two reactions are different. Catalytic reactions involve a metal-alkyl complex. This has been confirmed by reactions of deuterium-labeled substrates and different alkylating agents. Under the stoichiometric conditions, however, titanium olefin complexes are formed through reductive elimination, probably through a multinuclear intermediate.

  15. 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.

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

    PubMed Central

    Deville, Sylvain; Meille, Sylvain; Seuba, Jordi

    2015-01-01

    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. PMID:27877817

  17. 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

  18. A sodalite-type porous metal-organic framework with polyoxometalate templates: adsorption and decomposition of dimethyl methylphosphonate.

    PubMed

    Ma, Feng-Ji; Liu, Shu-Xia; Sun, Chun-Yan; Liang, Da-Dong; Ren, Guo-Jian; Wei, Feng; Chen, Ya-Guang; Su, Zhong-Min

    2011-03-30

    A sodalite-type porous metal-organic framework with polyoxometalate templates, H(3)[(Cu(4)Cl)(3)(BTC)(8)](2)[PW(12)O(40)]·(C(4)H(12)N)(6)·3H(2)O (NENU-11; BTC = 1,3,5-benzenetricarboxylate), was obtained by a hydrothermal reaction. As a reasonable candidate for eliminating nerve gas, NENU-11 displays good adsorption behavior for dimethyl methylphosphonate (15.5 molecules per formula unit). In virtue of the catalytic activity of polyoxometalate guests, this nerve gas mimic could be facilely decomposed by a hydrolysis reaction.

  19. 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.

  20. 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...

  1. Rapid (<3 min) microwave synthesis of block copolymer templated ordered mesoporous metal oxide and carbonate films using nitrate-citric acid systems.

    PubMed

    Zhang, Yuanzhong; Bhaway, Sarang M; Wang, Yi; Cavicchi, Kevin A; Becker, Matthew L; Vogt, Bryan D

    2015-03-25

    Rapid chemical transformation from micelle templated precursors (metal nitrate and citric acid) to ordered mesoporous metal carbonates and oxides is demonstrated using microwave heating for cobalt, copper, manganese and zinc. Without aging requirements, <3 min of microwave processing yields highly ordered mesoporous films.

  2. Template copolymerization to control site structure around metal ions: Applications towards sensing and gas storage and release

    NASA Astrophysics Data System (ADS)

    Mitchell-Koch, Jeremy T.

    The development of functional materials for sensing and gas storage and release is useful in a number of chemical and biological applications. Investigating function of molecularly imprinted polymers (MIP), often used for these purposes, has relied on circumstantial evidence because direct examination of immobilized sites is not possible. Described in this dissertation is the design, synthesis, characterization and function studies of materials synthesized by template copolymerization methods. Metal ions exhibit unique spectroscopic properties and their utilization makes site examination more feasible. Ligand binding modulates these properties such that the event can be measured by spectroscopy. The metal ion's secondary coordination environment can also be tuned to increase or decrease function of the material. In Chapter Two the utilization of template copolymerization to immobilize a europium-containing compound for the detection of volatile organic compounds is described. Luminescence of the immobilized complex is quenched in the presence of volatile organic compounds (VOC). The quenching effect is dependent on concentration of VOC and the nature of polymeric host. Chapters Three and Four describe the development of materials for the photolytic release of nitric oxide (NO). In Chapter Three, a novel manipulation of the immobilized complex is employed to produce binding sites that contain ligands covalently embedded into the host in a position to bind the metal ion upon NO release in order to block rebinding. Incompatible binding affinities of the iron-containing templates made it impossible to study NO photo-release from this material. Second-row transition metals are more compatible with NO binding, and Chapter Four describes a ruthenium salen-containing polymer that releases NO in response to light. Additionally, transfer of NO to a metalloporphyrin and myoglobin has been achieved. This is the first report of photolytic heterogeneous NO transfer by a material

  3. Preparation and characterization of two-dimensional metallic nanoparticle and void films derived from a colloidal template layer.

    PubMed

    Sepsi, Örs; Pothorszky, Szilárd; Nguyen, Tuan Máté; Zámbó, Dániel; Ujhelyi, Ferenc; Lenk, Sándor; Koppa, Pál; Deák, András

    2016-01-25

    A novel and simple bottom-up fabrication method for the realization of metallic nanovoid and metallic film on nanoparticle (dome) array is presented and their optical performance assessed based on experimental and theoretical investigations. The structures are created by a simple, annealing induced replica formation of a template monolayer, which is composed of submicron particles deposited on top of a thin polymer film. Angle and wavelength dependent reflection measurements indicate the possibility to excite Bragg plasmons at the prepared structures. We found an excellent agreement between the measured and simulated reflection curves, but only when the simulated reflection was averaged over several possible azimuthal lattice orientations of the hexagonal unit cell with respect to the plane of incidence.

  4. Low-temperature oriented growth of vanadium dioxide films on CoCrTa metal template on Si and vertical metal-insulator transition

    SciTech Connect

    Okimura, Kunio; Mian, Md.Suruz

    2012-09-15

    The authors achieved oriented growth of vanadium dioxide (VO{sub 2}) films on CoCrTa metal template grown on an Si substrate. Low-temperature ({approx}250 Degree-Sign C) deposition of VO{sub 2} films using inductively coupled-plasma-assisted sputtering technique realized an abrupt interface between VO{sub 2} and CoCrTa layers, suppressing the oxidation and diffusion of metal components. The films revealed a metal-insulator transition with resistance change of over 2 orders of magnitude. The CoCrTa film, in which Co hexagonal crystalline grains with c-axis orientation were surrounded by segregated Cr and Ta, serves for the oriented growth of VO{sub 2} crystalline film, enabling higher orders of transition in resistance and low voltage switching, even for the vertical (out-of-plane) direction.

  5. Control of Partial Coalescence of Self-Assembled Metal Nano-Particles across Lyotropic Liquid Crystals Templates towards Long Range Meso-Porous Metal Frameworks Design

    PubMed Central

    Dumée, Ludovic F.; Lemoine, Jean-Baptiste; Ancel, Alice; Hameed, Nishar; He, Li; Kong, Lingxue

    2015-01-01

    The formation of purely metallic meso-porous metal thin films by partial interface coalescence of self-assembled metal nano-particles across aqueous solutions of Pluronics triblock lyotropic liquid crystals is demonstrated for the first time. Small angle X-ray scattering was used to study the influence of the thin film composition and processing conditions on the ordered structures. The structural characteristics of the meso-structures formed demonstrated to primarily rely on the lyotropic liquid crystal properties while the nature of the metal nano-particles used as well as the their diameters were found to affect the ordered structure formation. The impact of the annealing temperature on the nano-particle coalescence and efficiency at removing the templating lyotropic liquid crystals was also analysed. It is demonstrated that the lyotropic liquid crystal is rendered slightly less thermally stable, upon mixing with metal nano-particles and that low annealing temperatures are sufficient to form purely metallic frameworks with average pore size distributions smaller than 500 nm and porosity around 45% with potential application in sensing, catalysis, nanoscale heat exchange, and molecular separation. PMID:28347094

  6. 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

  7. "Dual-template" synthesis of one-dimensional conductive nanoparticle superstructures from coordination metal-peptide polymer crystals.

    PubMed

    Rubio-Martínez, Marta; Puigmartí-Luis, Josep; Imaz, Inhar; Dittrich, Petra S; Maspoch, Daniel

    2013-12-20

    Bottom-up fabrication of self-assembled structures made of nanoparticles may lead to new materials, arrays and devices with great promise for myriad applications. Here a new class of metal-peptide scaffolds is reported: coordination polymer Ag(I)-DLL belt-like crystals, which enable the dual-template synthesis of more sophisticated nanoparticle superstructures. In these biorelated scaffolds, the self-assembly and recognition capacities of peptides and the selective reduction of Ag(I) ions to Ag are simultaneously exploited to control the growth and assembly of inorganic nanoparticles: first on their surfaces, and then inside the structures themselves. The templated internal Ag nanoparticles are well confined and closely packed, conditions that favour electrical conductivity in the superstructures. It is anticipated that these Ag(I)-DLL belts could be applied to create long (>100 μm) conductive Ag@Ag nanoparticle superstructures and polymetallic, multifunctional Fe3 O4 @Ag nanoparticle composites that marry the magnetic and conductive properties of the two nanoparticle types.

  8. 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

  9. Templated assembly of Co-Pt nanoparticles via thermal and laser-induced dewetting of bilayer metal films.

    PubMed

    Oh, Yong-Jun; Kim, Jung-Hwan; Thompson, Carl V; Ross, Caroline A

    2013-01-07

    Templated dewetting of a Co/Pt metal bilayer film on a topographic substrate was used to assemble arrays of Co-Pt alloy nanoparticles, with highly uniform particle size, shape and notably composition compared to nanoparticles formed on an untemplated substrate. Solid-state and liquid-state dewetting processes, using furnace annealing and laser irradiation respectively, were compared. Liquid state dewetting produced more uniform, conformal nanoparticles but they had a polycrystalline disordered fcc structure and relatively low magnetic coercivity. In contrast, solid state dewetting enabled formation of magnetically hard, ordered L1(0) Co-Pt single-crystal particles with coercivity >12 kOe. Furnace annealing converted the nanoparticles formed by liquid state dewetting into the L1(0) phase.

  10. 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.

  11. 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

    2011-04-04

    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.

  12. 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.

  13. Fabrication of Meso-Porous Sintered Metal Thin Films by Selective Etching of Silica Based Sacrificial Template

    PubMed Central

    Dumée, Ludovic F.; She, Fenghua; Duke, Mikel; Gray, Stephen; Hodgson, Peter; Kong, Lingxue

    2014-01-01

    Meso-porous metal materials have enhanced surface energies offering unique surface properties with potential applications in chemical catalysis, molecular sensing and selective separation. In this paper, commercial 20 nm diameter metal nano-particles, including silver and copper were blended with 7 nm silica nano-particles by shear mixing. The resulted powders were cold-sintered to form dense, hybrid thin films. The sacrificial silica template was then removed by selective etching in 12 wt% hydrofluoric acid solutions for 15 min to reveal a purely metallic meso-porous thin film material. The impact of the initial silica nano-particle diameter (7–20 nm) as well as the sintering pressure (5–20 ton·m−2) and etching conditions on the morphology and properties of the final nano-porous thin films were investigated by porometry, pyknometery, gas and liquid permeation and electron microscopy. Furthermore, the morphology of the pores and particle aggregation during shear mixing were assessed through cross-sectioning by focus ion beam milling. It is demonstrated that meso-pores ranging between 50 and 320 nm in average diameter and porosities up to 47% can be successfully formed for the range of materials tested.

  14. A metal-organic framework-templated synthesis of γ-Fe2O3 nanoparticles encapsulated in porous carbon for efficient and chemoselective hydrogenation of nitro compounds.

    PubMed

    Li, Yang; Zhou, Yu-Xiao; Ma, Xiao; Jiang, Hai-Long

    2016-03-18

    The γ-Fe2O3 nanoparticles well dispersed in porous carbon were fabricated via a Fe-based metal-organic framework-templated pyrolysis. The resultant product exhibits excellent catalytic activity, chemoselectivity and magnetic recyclability for the hydrogenation of diverse nitro compounds under mild conditions.

  15. 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.

  16. Alkoxide-based precursors for direct electrospinning of alumina fibers

    NASA Astrophysics Data System (ADS)

    Maneeratana, Vasana

    The vision for space exploration in 2004 reinvigorated excitement that was engendered during the 1960's space race. Looking to assist NASA's agency wide mission to develop new technologies to enhance space travel, it is the ultimate goal of this work to support future missions with a hand-held electrospinning apparatus to instantaneously repair existing crucial ceramic fiber structures, such as spacesuits, insulative foams, and tiles. In this research, a new type of precursor is designed based from aluminum alkoxide-based precursors, since alumina serves as a base material for a majority of high-temperature applications. The structure-processing behavior of these precursors is subsequently studied. New precursors of aluminum alkoxides were prepared by modifying solutions; as a result various types of structures were produced, ranging from continuous hollow fibers, continuous solid fibers, or hollow particles. Direct electrospinning with these alkoxide-based precursors yielded an average of 1.9 g/hr of Al2O3, compared to literature with the highest theoretical yield calculated to be 0.68 g/hr. Further exploration of electrospinning parameters found that flow rate directly related to exposure times; therefore fibers were produced in the atmosphere through hydrolysis/condensation with simultaneous solvent evaporation. Furthermore other processing parameters, including the effect of the microstructure due to processing in an electric field were studied. It was found that electrospinning promotes the reaction of the alkoxide, which thereby reduces trapped solvents. As a result of firing schedules, the fibers' hollow features were preserved, and precursors with volatile species resulted in near net shaped fibers. At low firing temperatures, specific surface areas in the range of 330-345 m 2/g were found electrospun fibers. Additionally modified precursors lowered alpha transitions of fibers down to ˜900°C.

  17. 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.

  18. 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.

  19. Salt-Templated Synthesis of 2D Metallic MoN and Other Nitrides.

    PubMed

    Xiao, Xu; Yu, Huimin; Jin, Huanyu; Wu, Menghao; Fang, Yunsheng; Sun, Jiyu; Hu, Zhimi; Li, Tianqi; Wu, Jiabin; Huang, Liang; Gogotsi, Yury; Zhou, Jun

    2017-02-28

    Two-dimensional (2D) transition-metal nitrides just recently entered the research arena, but already offer a potential for high-rate energy storage, which is needed for portable/wearable electronics and many other applications. However, a lack of efficient and high-yield synthesis methods for 2D metal nitrides has been a major bottleneck for the manufacturing of those potentially very important materials, and only MoN, Ti4N3, and GaN have been reported so far. Here we report a scalable method that uses reduction of 2D hexagonal oxides in ammonia to produce 2D nitrides, such as MoN. MoN nanosheets with subnanometer thickness have been studied in depth. Both theoretical calculation and experiments demonstrate the metallic nature of 2D MoN. The hydrophilic restacked 2D MoN film exhibits a very high volumetric capacitance of 928 F cm(-3) in sulfuric acid electrolyte with an excellent rate performance. We expect that the synthesis of metallic 2D MoN and two other nitrides (W2N and V2N) demonstrated here will provide an efficient way to expand the family of 2D materials and add many members with attractive properties.

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

    NASA Astrophysics Data System (ADS)

    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.

  1. Metal complexes of chiral pentaazacrowns as conformational templates for β-turn recognition

    NASA Astrophysics Data System (ADS)

    Reaka, Andrea J. H.; Ho, Chris M. W.; Marshall, Garland R.

    2002-08-01

    Examples of reverse turns as recognition motifs in biological systems can be found in high-resolution crystal structures of antibody-peptide complexes. Development of peptidomimetics is often based on replacing the amide backbone of peptides by sugar rings, steroids, benzodiazepines, or other hetero- and carbocycles. In this approach, the chemical scaffold of the peptide backbone can be replaced while retaining activity as long as the pharmacophoric groups of the peptide side chains stay in relatively the same place; in other words, similar functional groups must overlap in space for interaction with critical receptor sites. This study evaluates the potential of metal complexes of chiral pentaazacrowns (PAC) derived by reduction of cyclic pentapeptides as β-turn mimetics. Due to the limited flexibility of the pendant chiral side groups in these metal complexes, one can potentially elicit information about the receptor-bound conformation from their binding affinities. 11 PAC crystal structures with different substitution patterns complexed with 3 different metals (Mn, Fe, Cd) as a prototypical database of potential side-chain orientations. Complexation with different metals induces subtle differences in the conformations of a particular azacrown scaffold. The lack of parameterization of transition metals for force field calculations precludes a thorough theoretical study. Thus, this study utilizes a simple geometrical comparison between the experimental data for crystalline PAC complexes and the side-chain orientations seen in classic β-turns. The FOUNDATION program was used to overlap the Cα-Cβ vectors of the corresponding ideal β-turn side-chains to all possible leaving groups of the PAC complexes. When comparing the relative orientations of the chiral side chains, a strong overlap of the bonds (between about 0.1 Å to about 0.5 Å RMS for 3 residues and up to about 1 Å RMS for 4 residues) was observed for many of the molecules. Such metal complexes may lack

  2. 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

    2013-09-01

    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.

  3. Graphene as a flexible template for controlling magnetic interactions between metal atoms.

    PubMed

    Lee, Sungwoo; Kim, Dongwook; Robertson, Alex W; Yoon, Euijoon; Hong, Suklyun; Ihm, Jisoon; Yu, Jaejun; Warner, Jamie H; Lee, Gun-Do

    2017-03-01

    Metal-doped graphene produces magnetic moments that have potential application in spintronics. Here we use density function theory computational methods to show how the magnetic interaction between metal atoms doped in graphene can be controlled by the degree of flexure in a graphene membrane. Bending graphene by flexing causes the distance between two substitutional Fe atoms covalently bonded in graphene to gradually increase and these results in the magnetic moment disappearing at a critical strain value. At the critical strain, a carbon atom can enter between the two Fe atoms and blocks the interaction between relevant orbitals of Fe atoms to quench the magnetic moment. The control of interactions between doped atoms by exploiting the mechanical flexibility of graphene is a unique approach to manipulating the magnetic properties and opens up new opportunities for mechanical-magnetic 2D device systems.

  4. Graphene as a flexible template for controlling magnetic interactions between metal atoms

    NASA Astrophysics Data System (ADS)

    Lee, Sungwoo; Kim, Dongwook; Robertson, Alex W.; Yoon, Euijoon; Hong, Suklyun; Ihm, Jisoon; Yu, Jaejun; Warner, Jamie H.; Lee, Gun-Do

    2017-03-01

    Metal-doped graphene produces magnetic moments that have potential application in spintronics. Here we use density function theory computational methods to show how the magnetic interaction between metal atoms doped in graphene can be controlled by the degree of flexure in a graphene membrane. Bending graphene by flexing causes the distance between two substitutional Fe atoms covalently bonded in graphene to gradually increase and these results in the magnetic moment disappearing at a critical strain value. At the critical strain, a carbon atom can enter between the two Fe atoms and blocks the interaction between relevant orbitals of Fe atoms to quench the magnetic moment. The control of interactions between doped atoms by exploiting the mechanical flexibility of graphene is a unique approach to manipulating the magnetic properties and opens up new opportunities for mechanical-magnetic 2D device systems.

  5. Conformal sol-gel coatings on three-dimensional nanostructured templates

    NASA Astrophysics Data System (ADS)

    Weatherspoon, Michael R.

    Sol-gel processing techniques, such as spin coating and dip coating, have successfully been utilized over the past several decades to apply conformal coatings on planar substrates; however, controlled film growth on three-dimensional (3-D) nanostructured templates using the sol-gel process remains a significant challenge. Obstacles such as, uncontrolled hydrolyzation and condensation of metal alkoxide precursors on nanostructured surfaces are a few of the obstacles which lead to coatings with undesirable thicknesses and excess inorganic particles. A little over a decade ago, a surface sol-gel process was developed which utilizes stepwise film growth of anhydrous metal alkoxide precursors with hydroxylated surfaces. The surface sol-gel process provides control over the applied coating thickness and is viewed as a wet chemical analog to atomic layer deposition (ALD). The work presented in this dissertation has focused on applying conformal sol-gel derived coatings with controlled thicknesses on 3-D nanostructured templates. The templates utilized in this work were derived from biological species, such as diatoms and butterflies, as well as a synthetic photoresist polymer (SU-8). Coatings were applied on the templates using a conventional reflux/evaporation deposition process and a custom-built computer controlled surface sol-gel pumping system. The coatings applied using the reflux/evaporation process yielded conformal coatings with uncontrolled film thicknesses whereas the coatings applied using the surface sol-gel process yielded conformal coatings with controlled thicknesses. Barium titanate and europium-doped barium titanate coatings were applied on diatom frustules using the reflux/evaporation deposition process. The silica-based diatom frustules had to first be converted into magnesia/silicon composite replicas using a gas/solid displacement reaction to render the template chemically compatible with the barium titanate-based coating. Conformal titanate

  6. Method to synthesize metal chalcogenide monolayer nanomaterials

    SciTech Connect

    Hernandez-Sanchez, Bernadette A.; Boyle, Timothy J.

    2016-12-13

    Metal chalcogenide monolayer nanomaterials can be synthesized from metal alkoxide precursors by solution precipitation or solvothermal processing. The synthesis routes are more scalable, less complex and easier to implement than other synthesis routes.

  7. 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.

  8. Anodized Aluminum Oxide Templated Synthesis of Metal-Organic Frameworks Used as Membrane Reactors.

    PubMed

    Yu, Yifu; Wu, Xue-Jun; Zhao, Meiting; Ma, Qinglang; Chen, Junze; Chen, Bo; Sindoro, Melinda; Yang, Jian; Han, Shikui; Lu, Qipeng; Zhang, Hua

    2017-01-09

    The incorporation of metal-organic frameworks (MOFs) into membrane-shaped architectures is of great importance for practical applications. The currently synthesized MOF-based membranes show many disadvantages, such as poor compatibility, low dispersity, and instability, which severely limit their utility. Herein, we present a general, facile, and robust approach for the synthesis of MOF-based composite membranes through the in situ growth of MOF plates in the channels of anodized aluminum oxide (AAO) membranes. After being used as catalysis reactors, they exhibit high catalytic performance and stability in the Knoevenagel condensation reaction. The high catalytic performance might be attributed to the intrinsic structure of MOF-based composite membranes, which can remove the products from the reaction zone quickly, and prevent the aggregation and loss of catalysts during reaction and recycling process.

  9. The new metal complex templated polyoxoborate(s) (POB(s)) structures. Synthesis, structural characterization, and hydrogen storage capacities

    NASA Astrophysics Data System (ADS)

    Ali Köse, Dursun; Yurdakul, Ömer; Şahin, Onur; Öztürk, Zeynel

    2017-04-01

    The polyoxoborate(s) (POB(s)) structures, including a neutral ligand-metal complex compound as a template, were synthesized and the structural characterizations were performed via single crystal X-ray diffraction, FTIR, 11B-NMR, solid state UV-Vis spectroscopy, SEM and elemental analysis methods. Moreover, the stabilization features were determined via TGA/DTA method. In addition, nitrogen and hydrogen adsorption measurements provided the realization to determine the pore size distribution, BET surface area, and hydrogen storage capacities. The molecular formulas of compounds were estimated as [Cu(C12H8N2)2(C2H3O2)][B5O6(OH)4]·2H3BO3·H2O (I) and [Ni(C12H8N2)2(H2O)2]·(B7O9(OH)5)·5H2O (II) and the existence of two different POB(s) structures as pentaborate (B5O6(OH)4) and heptaborate (B7O9(OH)5) within the compounds were observed. At last, it was found that the both structures have micro and mesoporosity with 0.407 and 1.480 m2/g BET surface areas, for the compound I and II, respectively. Moreover, within the same conditions, compound II could uptake 0.19 wt% hydrogen at 77 K and at the relative pressure of 1 while compound II uptakes 0.035 wt% hydrogen.

  10. Thermal stability of gold nanoparticles embedded within metal oxide frameworks fabricated by hybrid modifications onto sacrificial textile templates.

    PubMed

    Padbury, Richard P; Halbur, Jonathan C; Krommenhoek, Peter J; Tracy, Joseph B; Jur, Jesse S

    2015-01-27

    The stability and spatial separation of nanoparticles (NP's) is essential for employing their advantageous nanoscale properties. This work demonstrates the entrapment of gold NP's embedded in a porous inorganic matrix. Initially, gold NP's are decorated on fibrous nylon-6, which is used as an inexpensive sacrificial template. This is followed by inorganic modification using a novel single exposure cycle vapor phase technique resulting in distributed NP's embedded within a hybrid organic-inorganic matrix. The processing is extended to the synthesis of porous nanoflakes after calcination of the modified nylon-6 yielding a porous metal oxide framework surrounding the disconnected NP's with a surface area of 250 m(2)/g. A unique feature of this work is the use of a transmission electron microscope (TEM) equipped with an in situ annealing sample holder. The apparatus affords the opportunity to explore the underlying nanoscopic stability of NP's embedded in these frameworks in a single step. TEM analysis indicates thermal stability up to 670 °C and agglomeration characteristics thereafter. The vapor phase processes developed in this work will facilitate new complex NP/oxide materials useful for catalytic platforms.

  11. 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

    2012-01-03

    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.

  12. The rhodium catalyzed three-component reaction of diazoacetates, titanium(IV) alkoxides and aldehydes.

    PubMed

    Lu, Chong-Dao; Liu, Hui; Chen, Zhi-Yong; Hu, Wen-Hao; Mi, Ai-Qiao

    2005-05-28

    The rhodium(II)-catalyzed three-component reaction of diazoacetates, titanium alkoxides and aldehydes is shown to give alpha-alkoxyl-beta-hydroxyl acid derivatives; the novel C-C bond formation reaction is proposed to occur through oxonium ylides derived from diazo compounds and titanium alkoxides, and followed by intermolecular trapping by aldehydes.

  13. 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.

  14. Method for making monolithic metal oxide aerogels

    DOEpatents

    Coronado, Paul R.

    1999-01-01

    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 containment vessel is enclosed within an aqueous atmosphere that is above the supercritical temperature and pressure of the solvent of the metal alkoxide solution.

  15. 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.

  16. Epimerization of secondary alcohols by new homogeneous, low oxidation state metal catalysts: Carbon-hydrogen bond activation in rhenium alkoxide complexes ({eta}{sup 5}-C{sub 5}R{sub 5})Re(NO)(PPh{sub 3})(OCHRR{prime})

    SciTech Connect

    Saura-Llamas, I.; Gladysz, J.A.

    1992-03-11

    Diastereomerically pure secondary alcohols epimerize to mixtures of diasteromers in C{sub 6}H{sub 5}R at 65-90 {degrees}C in the presence of 10 mol% ({eta}{sup 5}C{sub 5}R{sub 5})Re(NO)(PPh{sub 3})(OCH{sub 3}) (1; R = H, Me). The methoxide ligand of 1 first exchanges with the alcohol substrate to give alkoxide complexes {eta}{sup 5}-C{sub 5}R{sub 5})Re(NO)(PPh{sub 3})(OCHR{prime}R{double_prime} is derived from (+)- and (-)-, exo- and endo-borneol. NMR data show that epimerization occurs first at rhenium (ca. 35 {degrees}C) and then at carbon (ca. 65 {degrees}C). Substitution reactions and rate experiments show that PPh{sub 3} initially dissociates from 2 with anchimeric assistance by alkoxide oxygen lone pairs. An intermediate with a trigonal-planar rhenium which can either return to 2 (with epimerization at rhenium) or undergo {beta}-hydride elimination to a ketone hydride complex (leading to epimerization at carbon), is proposed. Accordingly, rates of epimerization at carbon (but not rhenium) are strongly inhibited by added PPh{sub 3}, and show a significant k{sub H}/k{sub D}. 38 refs., 7 figs., 3 tabs.

  17. Assembly of a Metal-Organic Framework into 3 D Hierarchical Porous Monoliths Using a Pickering High Internal Phase Emulsion Template.

    PubMed

    Zhu, He; Zhang, Qi; Zhu, Shiping

    2016-06-20

    3D Hierarchical porous metal-organic framework (MOF) monoliths are prepared by using Pickering high internal phase emulsion (HIPE) template. Pickering HIPEs were stabilized solely by UiO-66 MOF particles with internal phase up to 90 % of the volume. The effects of internal phase type and volume, as well as MOF particle concentration on the stability of resulting Pickering HIPEs were investigated. Furthermore, by adding small amount of polyvinyl alcohol (PVA) as binder or polymerization in the continuous aqueous phase, followed by freeze-drying, two types of MOF-based 3D hierarchical porous monoliths with ultralow density (as low as 12 mg cm(-3) ) were successfully prepared. This Pickering HIPE template approach provides a facile and practical way for assembling of MOFs into complex structures.

  18. 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.

  19. A general salt-templating method to fabricate vertically aligned graphitic carbon nanosheets and their metal carbide hybrids for superior lithium ion batteries and water splitting.

    PubMed

    Zhu, Jixin; Sakaushi, Ken; Clavel, Guylhaine; Shalom, Menny; Antonietti, Markus; Fellinger, Tim-Patrick

    2015-04-29

    The synthesis of vertically aligned functional graphitic carbon nanosheets (CNS) is challenging. Herein, we demonstrate a general approach for the fabrication of vertically aligned CNS and metal carbide@CNS composites via a facile salt templating induced self-assembly. The resulting vertically aligned CNS and metal carbide@CNS structures possess ultrathin walls, good electrical conductivity, strong adhesion, excellent structural robustness, and small particle size. In electrochemical energy conversion and storage such unique features are favorable for providing efficient mass transport as well as a large and accessible electroactive surface. The materials were tested as electrodes in a lithium ion battery and in electrochemical water splitting. The vertically aligned nanosheets exhibit remarkable lithium ion storage properties and, concurrently, excellent properties as electrocatalysts for hydrogen evolution.

  20. Simultaneous electrochemical immunoassay using graphene-Au grafted recombinant apoferritin-encoded metallic labels as signal tags and dual-template magnetic molecular imprinted polymer as capture probes.

    PubMed

    Wang, De; Gan, Ning; Zhang, Huairong; Li, Tianhua; Qiao, Li; Cao, Yuting; Su, Xiurong; Jiang, Shan

    2015-03-15

    A novel electrochemical multiplexed immunoassay was designed for simultaneous determination of alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA) using recombinant apoferritin-encoded metallic nanoparticles (rApo-M) as labels and dual-template magnetic molecularly imprinted polymers (MMIPs) as capture probes. The labels were prepared by loading recombinant apoferritin (r-Apo) and separately immobilize primary antibodies (anti-AFP and anti-CEA) via Au nanoparticles of in site growth on graphene (G). The capture probes were synthesized by self-polymerization of dopamine (DA) on the Fe3O4 nanoparticles (Fe3O4 NPs) and using AFP and CEA as the template proteins, which were used to enrich the targets simultaneously. After a sandwich-type immunoreaction, the labels were captured to the surface of MMIPs. The subsequent electrochemical stripping analysis of the metal components from the immunocomplex provide a means for quantification of targets based on the peak currents of Cd and Pb. Experimental results showed the immunoassay enabled the simultaneous determination of AFP and CEA in a single run with wide dynamic ranges of 0.001-5ngmL(-1). And the detection limits of AFP and CEA were 0.3 and 0.35pgmL(-1) (S/N=3), respectively. These results suggested that the proposed multiplexed immunoassay would be applied for clinical screening of other biomarkers.

  1. Formation of Gold(III) Alkyls from Gold Alkoxide Complexes

    PubMed Central

    2017-01-01

    The gold(III) methoxide complex (C∧N∧C)AuOMe (1) reacts with tris(p-tolyl)phosphine in benzene at room temperature under O abstraction to give the methylgold product (C∧N∧C)AuMe (2) together with O=P(p-tol)3 ((C∧N∧C) = [2,6-(C6H3tBu-4)2pyridine]2–). Calculations show that this reaction is energetically favorable (ΔG = −32.3 kcal mol–1). The side products in this reaction, the Au(II) complex [Au(C∧N∧C)]2 (3) and the phosphorane (p-tol)3P(OMe)2, suggest that at least two reaction pathways may operate, including one involving (C∧N∧C)Au• radicals. Attempts to model the reaction by DFT methods showed that PPh3 can approach 1 to give a near-linear Au–O–P arrangement, without phosphine coordination to gold. The analogous reaction of (C∧N∧C)AuOEt, on the other hand, gives exclusively a mixture of 3 and (p-tol)3P(OEt)2. Whereas the reaction of (C∧N∧C)AuOR (R = But, p-C6H4F) with P(p-tol)3 proceeds over a period of hours, compounds with R = CH2CF3, CH(CF3)2 react almost instantaneously, to give 3 and O=P(p-tol)3. In chlorinated solvents, treatment of the alkoxides (C∧N∧C)AuOR with phosphines generates [(C∧N∧C)Au(PR3)]Cl, via Cl abstraction from the solvent. Attempts to extend the synthesis of gold(III) alkoxides to allyl alcohols were unsuccessful; the reaction of (C∧N∧C)AuOH with an excess of CH2=CHCH2OH in toluene led instead to allyl alcohol isomerization to give a mixture of gold alkyls, (C∧N∧C)AuR′ (R′ = −CH2CH2CHO (10), −CH2CH(CH2OH)OCH2CH=CH2 (11)), while 2-methallyl alcohol affords R′ = CH2CH(Me)CHO (12). The crystal structure of 11 was determined. The formation of Au–C instead of the expected Au–O products is in line with the trend in metal–ligand bond dissociation energies for Au(III): M–H > M–C > M–O.

  2. 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.

  3. 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.

  4. 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.

  5. Metal-Metal Bonds and Metal Carbon Bonds in the Chemistry of Molybdenum and Tungsten Alkoxides.

    DTIC Science & Technology

    1983-02-07

    diketones , 0-keto- esters, 0-ketoamines and Schiff bases. Insertion reactions also occur with unsaturated molecules such as CO CS and ArNCO. 02P 2 The...isopropoxy and neopentoxy compounds are oligomers [MoO 2(OR)21 n of, as yet, unknown struc- 2_no, syt unkow stuc 34 tures. A clean synthesis of the latter...to green solutions containing the triangulo Mo 30(OR)to compounds (see Figure 5). A clean, direct synthesis of these compounds is by the addition of

  6. 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.

  7. 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}.

  8. Dioximate- and Bis(salicylaldiminate)-Bridged Titanium and Zirconium Alkoxides: Structure Elucidation by Mass Spectrometry

    PubMed Central

    Maurer, Christian; Pittenauer, Ernst; Puchberger, Michael; Allmaier, Günter; Schubert, Ulrich

    2013-01-01

    The treatment of titanium alkoxides with 1,5-pentanedioxime or 2,5-hexanedioxime resulted in the formation of complexes [{TiL(OR)2}2] in which the dioximate ligands (L) bridge a dimeric Ti2(μ2-OR)2 unit. The structures of the complexes were determined by single-crystal structure analysis, ESI mass spectrometry, and 1D and 2D solution NMR spectroscopy. In contrast, the treatment of titanium alkoxides with dioximes bearing cyclic linkers, such as cyclohexyl or aryl groups, resulted in insoluble polymeric compounds. The treatment of various bis(salicylaldiminates) with titanium and zirconium alkoxides resulted in compounds with the same composition [{TiL(OR)2}2], in which, however, two monomeric Ti(OR)2 units are bridged by the ligands L. The two structural possibilities can be distinguished by low-energy collision-induced dissociation owing to their different fragmentation patterns. PMID:23795338

  9. 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.

  10. Dinuclear uranium alkoxides. Preparation and structures of KU/sub 2/(OCMe/sub 3/)/sub 9/, U/sub 2/(OCMe/sub 3/)/sub 9/, and U/sub 2/(OCHMe/sub 2/)/sub 10/, containing (U(IV),U(IV)), (U(IV),U(V)), and (U(V), U(V)), respectively

    SciTech Connect

    Cotton, F.A.; Marler, D.O.; Schwotzer, W.

    1984-12-05

    The structural results by x-ray crystallography are reported for three uranium alkoxides, two of which are new compounds. All three are dinuclear in the solid state, and they contain the following combinations of oxidation states; (U(IV), U(VI)), (U(V), U(IV)), and (U(V), U(V)). The crystal parameters and U...U bond distances are given for all three compounds. The terminal alkoxide groups in all three compounds display nearly linear U-O-C arrangements, with U-O-C bond angles between 160 and 176/sup 0/. This appears to be a general feature of uranium alkoxides and suggests a high degree of O..pi.. ..-->.. U contributions to the metal-oxygen bonds.

  11. 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

  12. Electrochemistry at nanoscale electrodes: individual single-walled carbon nanotubes (SWNTs) and SWNT-templated metal nanowires.

    PubMed

    Dudin, Petr V; Snowden, Michael E; Macpherson, Julie V; Unwin, Patrick R

    2011-12-27

    Individual nanowires (NWs) and native single-walled carbon nanotubes (SWNTs) can be readily used as well-defined nanoscale electrodes (NSEs) for voltammetric analysis. Here, the simple photolithography-free fabrication of submillimeter long Au, Pt, and Pd NWs, with sub-100 nm heights, by templated electrodeposition onto ultralong flow-aligned SWNTs is demonstrated. Both individual Au NWs and SWNTs are employed as NSEs for electron-transfer (ET) kinetic quantification, using cyclic voltammetry (CV), in conjunction with a microcapillary-based electrochemical method. A small capillary with internal diameter in the range 30-70 μm, filled with solution containing a redox-active mediator (FcTMA(+) ((trimethylammonium)methylferrocene), Fe(CN)(6)(4-), or hydrazine) is positioned above the NSE, so that the solution meniscus completes an electrochemical cell. A 3D finite-element model, faithfully reproducing the experimental geometry, is used to both analyze the experimental CVs and derive the rate of heterogeneous ET, using Butler-Volmer kinetics. For a 70 nm height Au NW, intrinsic rate constants, k(0), up to ca. 1 cm s(-1) can be resolved. Using the same experimental configuration the electrochemistry of individual SWNTs can also be accessed. For FcTMA(+/2+) electrolysis the simulated ET kinetic parameters yield very fast ET kinetics (k(0) > 2 ± 1 cm s(-1)). Some deviation between the experimental voltammetry and the idealized model is noted, suggesting that double-layer effects may influence ET at the nanoscale.

  13. 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.

  14. 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.

  15. Metal-Organic Framework Templated Synthesis of Ultrasmall Catalyst Loaded ZnO/ZnCo2O4 Hollow Spheres for Enhanced Gas Sensing Properties

    PubMed Central

    Koo, Won-Tae; Choi, Seon-Jin; Jang, Ji-Soo; Kim, Il-Doo

    2017-01-01

    To achieve the rational design of nanostructures for superior gas sensors, the ultrasmall nanoparticles (NPs) loaded on ternary metal oxide (TMO) hollow spheres (HS) were synthesized by using the polystyrene (PS) sphere template and bimetallic metal-organic framework (BM-MOFs) mold. The zinc and cobalt based zeolite imidazole frameworks (BM-ZIFs) encapsulating ultrasmall Pd NPs (2–3 nm) were assembled on PS spheres at room temperature. After calcination at 450 °C, these nanoscale Pd particles were effectively infiltrated on the surface of ZnO/ZnCo2O4 HSs. In addition, the heterojunctions of Pd-ZnO, Pd-ZnCo2O4, and ZnO-ZnCo2O4 were formed on each phase. The synthesized Pd-ZnO/ZnCo2O4 HSs exhibited extremely high selectivity toward acetone gas with notable sensitivity (S = 69% to 5 ppm at 250 °C). The results demonstrate that MOF driven ultrasmall catalyst loaded TMO HSs were highly effective platform for high performance chemical gas sensors. PMID:28327599

  16. Non-noble metal Bi deposition by utilizing Bi2WO6 as the self-sacrificing template for enhancing visible light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Yu, Shixin; Zhang, Yihe; Li, Min; Du, Xin; Huang, Hongwei

    2017-01-01

    Bi metal deposited on Bi2WO6 composite photocatalysts have been successfully synthesized via a simple in-situ reduction method at room temperature with using Bi2WO6 as self-sacrificing template and NaBH4 as reducing agent. The reduction extent can be easily modulated by controlling the concentration of NaBH4 solution. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FTIR) spectra, N2 adsorption-desorption isotherms, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution TEM (HRTEM), diffuse reflection spectroscopy (DRS) and photoelectrochemical measurements were carried out to analyze the phase, morphology, optical property and photoelectrochemical property of the as-prepared samples. The photocatalytic activity is surveyed by degradation of phenol under visible light (λ > 420 nm), which showed that the BWO-0.2 photocatalyst exhibited the highest efficiency, which was over 3 times as high as pure Bi2WO6. The enhanced photocatalytic activity should be attributed to strengthened photoabsorption and charge separation efficiency derived from the surface plasmon resonance (SPR) of Bi metal.

  17. 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

    2014-10-08

    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.

  18. 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.

  19. Metal-Organic Framework Templated Synthesis of Ultrasmall Catalyst Loaded ZnO/ZnCo2O4 Hollow Spheres for Enhanced Gas Sensing Properties

    NASA Astrophysics Data System (ADS)

    Koo, Won-Tae; Choi, Seon-Jin; Jang, Ji-Soo; Kim, Il-Doo

    2017-03-01

    To achieve the rational design of nanostructures for superior gas sensors, the ultrasmall nanoparticles (NPs) loaded on ternary metal oxide (TMO) hollow spheres (HS) were synthesized by using the polystyrene (PS) sphere template and bimetallic metal-organic framework (BM-MOFs) mold. The zinc and cobalt based zeolite imidazole frameworks (BM-ZIFs) encapsulating ultrasmall Pd NPs (2–3 nm) were assembled on PS spheres at room temperature. After calcination at 450 °C, these nanoscale Pd particles were effectively infiltrated on the surface of ZnO/ZnCo2O4 HSs. In addition, the heterojunctions of Pd-ZnO, Pd-ZnCo2O4, and ZnO-ZnCo2O4 were formed on each phase. The synthesized Pd-ZnO/ZnCo2O4 HSs exhibited extremely high selectivity toward acetone gas with notable sensitivity (S = 69% to 5 ppm at 250 °C). The results demonstrate that MOF driven ultrasmall catalyst loaded TMO HSs were highly effective platform for high performance chemical gas sensors.

  20. Hydroxyapatite Nanowires@Metal-Organic Framework Core/Shell Nanofibers: Templated Synthesis, Peroxidase-Like Activity, and Derived Flexible Recyclable Test Paper.

    PubMed

    Chen, Fei-Fei; Zhu, Ying-Jie; Xiong, Zhi-Chao; Sun, Tuan-Wei

    2017-03-08

    The templated synthesis of hydroxyapatite (HAP) nanowires@metal-organic framework (MOF) core/shell nanofibers (named HAP@MIL-100(Fe) nanofibers) is demonstrated. The ultralong hydroxyapatite nanowires are adopted as a hard template for the nucleation and growth of MIL-100(Fe) (a typical MOF) through the layer-by-layer method. The Coulombic and chelation interactions between Ca(2+) ions on the surface of the HAP nanowires and the COO(-) organic linkers of MIL-100(Fe) play key roles in the formation process. The as-prepared, water-stable HAP@MIL-100(Fe) nanofibers exhibit peroxidase-like activity toward the oxidation of different peroxidase substrates in the presence of H2 O2 , accompanied by a clear color change of the solution. Furthermore, a flexible, recyclable HAP@MIL-100(Fe) test paper is prepared successfully by using HAP@MIL-100(Fe) nanofibers as building blocks. A simple, low-cost, and sensitive colorimetric method for the detection of H2 O2 and glucose is established based on the as-prepared, flexible, recyclable HAP@MIL-100(Fe) test paper. More importantly, the HAP@MIL-100(Fe) test paper can be recovered easily for reuse by simply dipping in absolute ethanol for just 30 min, thus showing excellent recyclability. With its combination of advantages such as easy transportation, easy storage and use, rapid recyclability, light weight, and high flexibility, this HAP@MIL-100(Fe) test paper is promising for wide applications in various fields.

  1. 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.

  2. 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

  3. 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).

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

    NASA Astrophysics Data System (ADS)

    Baksi, Ananya; Pradeep, T.

    2013-11-01

    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+, Pt2+, Pd2+, Cu2+, Fe2+, Ni2+ and Cr3+) 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 Cu2+ help forming Au25+ selectively, Fe2+ 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.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+, Pt2+, Pd2+, Cu2+, Fe2+, Ni2+ and Cr3+) 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 Cu2+ help forming Au25+ selectively, Fe2+ catalyzes the formation of Au25+ over all other clusters. Gas phase cluster

  5. Nitrogen-doped graphene quantum dots-labeled epitope imprinted polymer with double templates via the metal chelation for specific recognition of cytochrome c.

    PubMed

    Yan, Yun-Jing; He, Xi-Wen; Li, Wen-You; Zhang, Yu-Kui

    2017-05-15

    A novel fluorescent sensor nitrogen-doped graphene quantum dots (N-GQDs)/SiO2/molecular imprinting polymer(N-GQDs/SiO2/MIP)was fabricated by surface imprinting and epitope imprinting to recognize and detect the target protein cytochrome c (Cyt C) with fluorescence quenching. In the polymerization process, the C- and N-terminal nonapeptides of Cyt C were selected as the double templates which were fixed by functional monomer (zinc acrylate) through metal chelation and steady six-membered ring. The linear range of fluorescence quenching for this receptor towards Cyt C was 0.20-60μM, and the detection limit was 0.11μM. The precision for six times replicate determination of Cyt C at 30μM was 1.20%, and the imprinting factor (IF) was 3.06. The recoveries of the material to Cyt C in urine were 99.3-114.0%. In brief, this work proposed a strategy to prepare a new type fluorescent imprinting polymer based on N-GQDs and provided an attractive perspective for the detection of protein by using the combination of N-GQDs and molecular imprinting technique.

  6. Gum Arabic Microgels As Template for In Situ Metal-Sulfide Based Quantum Dots Preparation and Their Thermal, Spectroscopic, Optical, and Magnetic Characterization

    NASA Astrophysics Data System (ADS)

    Farooq, Muhammad; Sagbas, Selin; Yildiz, Mustafa; Meral, Kadem; Siddiq, Mohammad; Aktas, Nahit; Sahiner, Nurettin

    2017-03-01

    Here, gum arabic (GA) microgel in 5-50 μm size range was used as a template for in situ quantum dot (QD) preparation. The in situ synthesis of metal sulfide quantum dots (QDs) such as CdS, PbS, CuS, ZnS, CoS, and MnS was accomplished by the absorption of the corresponding metal ions from aqueous solutions and then in situ precipitation with S2- treatments within GA microgels. Transmission electron microscopy (TEM) confirmed the existence of the evenly distributed QDs within GA microgel matrices for each of the prepared QDs. All the fabricated GA-QD composites have shown excellent semiconducting behaviors with relatively larger band gap values of 4.87 eV, 4.60 eV, 6.71 eV, 4.81 eV, 3.68 eV, 5.2 eV, and 4.0 eV for CdS, PbS, ZnS, CuS, CoS, MoS, and MnS, respectively. The results revealed that CdS and ZnS are found to be the most efficient florescence materials amongst the all QDs with 630 and 70 cd/cm2 fluorescence intensities, respectively. Moreover, the magnetic susceptibility study suggests that Mn(IV), Co(III), and Mo(IV), have mononuclear octahedral geometries whereas Zn(II), Cd(II), and Pb(II) show binuclear geometries.

  7. 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.

  8. 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.

  9. 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.

  10. Crystal Structure of the Isopropylzinc Alkoxide of Pyrimidyl Alkanol: Mechanistic Insights for Asymmetric Autocatalysis with Amplification of Enantiomeric Excess.

    PubMed

    Matsumoto, Arimasa; Abe, Takaaki; Hara, Atsushi; Tobita, Takayuki; Sasagawa, Taisuke; Kawasaki, Tsuneomi; Soai, Kenso

    2015-12-07

    Asymmetric amplification during self-replication is a key feature that is used to explain the origin of homochirality. Asymmetric autocatalysis of pyrimidyl alkanol in the asymmetric addition of diisopropylzinc to pyrimidine-5-carbaldehyde is a unique example of this phenomenon. Crystallization of zinc alkoxides of this 5-pyrimidyl alkanol and single-crystal X-ray diffraction analysis of the alkoxide crystals reveal the existence of tetramer or higher oligomer structures in this asymmetric autocatalytic system.

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

    PubMed

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

    2013-11-06

    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.

  12. 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.

  13. Steric vs electronic effects in binary uranyl alkoxides: A spectroscopic perspective

    NASA Astrophysics Data System (ADS)

    Morris, David E.; Wilkerson, Marianne P.; Burns, Carol J.; Scott, Brian L.; Wilkerson, Marianne P.; Paine, Robert T.

    2000-07-01

    Recent advances in the non-aqueous alkoxide chemistry of UO22+ have provided the wherewithal to prepare and isolate a broad range of discrete molecular uranyl entities both as solids and in aprotic solvents in which it is possible to tune the ligand basicity and steric encumbrance. Uranyl complexes have been isolated as monomers, dimers, and higher order oligomers. These complexes afford an opportunity to examine in some detail the relative importance of ligand basicity and steric demand in directing structural preferences (monomer vs. dimer, cis vs. trans isomers) and in determining electronic structural properties and relative bond strengths in the "yl" and equatorial bonds. In the present report the electronic and vibrational spectroscopic data for a series of uranyl alkoxides are correlated with molecular structural data to examine trends in electronic structure and bonding and compare these results with existing models based on the more classical uranyl coordination compounds.

  14. 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.

  15. 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.

  16. 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.

  17. Templated and template-free fabrication strategies for zero-dimensional hollow MOF superstructures.

    PubMed

    Kim, Hyehyun; Lah, Myoung Soo

    2017-03-23

    Various fabrication strategies for hollow metal-organic framework (MOF) superstructures are reviewed and classified using various types of external templates and their properties. Hollow MOF superstructures have also been prepared without external templates, wherein unstable intermediates obtained during reactions convert to the final hollow MOF superstructures. Many hollow MOF superstructures have been fabricated using hard templates. After the core-shell core@MOF structure was prepared using a hard template, the core was selectively etched to generate a hollow MOF superstructure. Another approach for generating hollow superstructures is to use a solid reactant as a sacrificial template; this method requires no additional etching process. Soft templates such as discontinuous liquid/emulsion droplets and gas bubbles in a continuous soft phase have also been employed to prepare hollow MOF superstructures.

  18. Synthesis and characterization of amine-bridged bis(phenolate)lanthanide alkoxides and their application in the controlled polymerization of rac-lactide and rac-β-butyrolactone.

    PubMed

    Nie, Kun; Fang, Lei; Yao, Yingming; Zhang, Yong; Shen, Qi; Wang, Yaorong

    2012-10-15

    A series of neutral lanthanide alkoxides supported by an amine-bridged bis(phenolate) ligand were synthesized, and their catalytic behaviors for the polymerization of rac-lactide (LA) and rac-β-butyrolactone (BBL) were explored. The reactions of (C(5)H(5))(3)Ln(THF) with amine-bridged bis(phenol) LH(2) [L = Me(2)NCH(2)CH(2)N{CH(2)-(2-OC(6)H(2)Bu(t)(2)-3,5)}(2)] in a 1:1 molar ratio in THF for 1 h and then with 1 equiv each of 2,2,2-trifluoroethanol, benzyl alcohol, and 2-propanol gave the neutral lanthanide alkoxides LLn(OCH(2)CF(3))(THF) [Ln = Y (1), Yb (2), Er (3), Sm (4)], LY(OCH(2)Ph)(THF) (5), and LY(OPr(i))(THF) (6), respectively. These lanthanide alkoxides are sensitive to moisture, and the yttrium complex [(LY)(2)(μ-OPr(i))(μ-OH)] (7) was also isolated as a byproduct during the synthesis of complex 6. Complexes 1-6 were well characterized by elemental analyses and IR and NMR spectroscopy in the cases of complexes 1 and 4-6. The definitive molecular structures of all of these complexes were determined by single-crystal X-ray analysis. It was found that complexes 1-6 can initiate efficiently the ring-opening polymerization of rac-LA and rac-BBL in a controlled manner. For rac-LA, polymerization gave polymers with very narrow molecular weight distributions (PDI ≤ 1.12) and very high heterotacticity (P(r) up to 0.99). The observed activity-increasing order is in agreement with the order of the ionic radii, whereas the order for stereoselectivity is in the reverse order. For rac-BBL polymerization, the resultant polymers have narrow molecular distributions (PDI ≤ 1.26) and high syndiotacticity (P(r) up to 0.83). It is worth noting that the activity-decreasing order Yb > Er > Y > Sm is observed for rac-BBL polymerization, which is opposite to the order of ionic radii and to the order of activity for rac-LA polymerization. The ionic radii of lanthanide metals have no obvious effect on the stereoselectivity for rac-BBL polymerization, which is quite

  19. 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.

  20. Spin crossover behavior in a series of iron(III) alkoxide complexes.

    PubMed

    Ortega-Villar, Norma; Guerrero-Estrada, Areli Yesareth; Piñeiro-López, Lucía; Muñoz, M Carmen; Flores-Álamo, Marcos; Moreno-Esparza, Rafael; Real, José A; Ugalde-Saldívar, Víctor M

    2015-04-06

    The synthesis, crystal structures, magnetic behavior, and electron paramagnetic resonance studies of five new Fe(III) spin crossover (SCO) complexes are reported. The [Fe(III)N5O] coordination core is constituted of the pentadentate ligand bztpen (N5) and a series of alkoxide anions (ethoxide, propoxide, n-butoxide, isobutoxide, and ethylene glycoxide). The methoxide derivative previously reported by us is also reinvestigated. The six complexes crystallize in the orthorhombic Pbca space group and show similar molecular structures and crystal packing. The coordination octahedron is strongly distorted in both the high- and low-temperature structures. The structural changes upon spin conversion are consistent with those previously observed for [Fe(III)N4O2] SCO complexes of the Schiff base type, except for the Fe-O(alkoxide) bond distance, which shortens significantly in the high-spin state. Application of the Slichter-Drickamer thermodynamic model to the experimental SCO curves afforded reasonably good simulations with typical enthalpy and entropy variations ranging in the intervals ΔH = 6-13 kJ mol(-1) and ΔS = 40-50 J mol(-1) K(-1), respectively. The estimated values of the cooperativity parameter Γ, found in the interval 0-2.2 kJ mol(-1), were consistent with the nature of the SCO. Electron paramagnetic resonance spectroscopy confirmed the transformation between the high-spin and low-spin states, characterized by signals at g ≈ 4.47 and 2.10, respectively. Electrochemical analysis demonstrated the instability of the Fe(II) alkoxide derivatives in solution.

  1. Synthesis and characterization of 2-hydroxy-pyridine modified Group 4 alkoxides

    DOE PAGES

    Boyle, Timothy J.; Sivonxay, Eric

    2016-05-19

    Here, the reaction of Group 4 metal alkoxides ([M(OR)4]) with the potentially bidentate ligand, 2-hydroxy-pyridine (2-HO-(NC5H4) or H-PyO), led to the isolation of a family of compounds. The products isolated from the reaction of [M(OR)4] [where M = Ti, Zr, or Hf; OR = OPri (OCH(CH3)2), OBut (OC(CH3)3), or ONep (OCH2C(CH3)3] under a variety of stoichiometries with H-PyO were identified by single crystal X-ray diffraction as [(OPri)2(PyO-κ2(O,N))Ti(μ-OPri)]2, [(ONep)2Ti(μ(O)-PyO-κ2(O,N))2(μ-ONep)Ti(ONep)3], [(ONep)2Ti(μ(O)-PyO-κ2(O,N))(η1(N),μ(O)-PyO)(μ-O)Ti(ONep)2]2, [H][(PyO-κ2(O,N))(η1(O)-PyO)Ti(ONep)3], [(OR)2Zr(μ(O)-PyO-κ2(O,N))2(μ-OR)Zr(OR)3] (OR = OBut, ONep), [(OR)2Zr(μ(O,N)-PyO-κ2(O,N))2(μ(O,N)-PyO)Zr(OR)3] (OR = OBut, ONep), [[(OBut)2Zr(μ(O)-PyO-(κ2(N,O))(μ(O,N)-PyO)2Zr(OBut)](μ3-O)]2, [[(ONep)(PyO-κ2(N,O))Zr(μ(O,N)-PyO-κ2(N,O))2(μ(O)-PyO-κ2(N,O))Zr(ONep)](μ3-O)]2, [(OBut)(PyO-κ2(O,N))Zr(μ(O)-PyO-κ2(O,N))2((μ(O,N)-PyO)Zr(OBut)3], [(OBut)2Hf(μ(O)-PyO-κ2(N,O))2(μ-OBut)Hf(OBut)3], [(OR)2 M(μ(O)-PyO-κ2(N,O))2(μ(O,N)-PyO)M(OR)3] (OR = OBut, ONep), and [(ONep)3Hf(μ-ONep)(η1(N),μ(O)-PyO)]2Hf(ONep)2·tol. The structural diversity of the binding modes ofmore » the PyO led to a number of novel structure types in comparison to other pyridine alkoxy derivatives. The majority of compounds adopt a dinuclear arrangement but oxo-based tetra-, tri-, and monomers were observed as well. Compounds 1–12 were further characterized using a variety of analytical techniques including Fourier Transform Infrared Spectroscopy, elemental analysis, and multinuclear NMR spectroscopy.« less

  2. Synthesis and characterization of 2-hydroxy-pyridine modified Group 4 alkoxides

    SciTech Connect

    Boyle, Timothy J.; Sivonxay, Eric

    2016-05-19

    Here, the reaction of Group 4 metal alkoxides ([M(OR)4]) with the potentially bidentate ligand, 2-hydroxy-pyridine (2-HO-(NC5H4) or H-PyO), led to the isolation of a family of compounds. The products isolated from the reaction of [M(OR)4] [where M = Ti, Zr, or Hf; OR = OPri (OCH(CH3)2), OBut (OC(CH3)3), or ONep (OCH2C(CH3)3] under a variety of stoichiometries with H-PyO were identified by single crystal X-ray diffraction as [(OPri)2(PyO-κ2(O,N))Ti(μ-OPri)]2, [(ONep)2Ti(μ(O)-PyO-κ2(O,N))2(μ-ONep)Ti(ONep)3], [(ONep)2Ti(μ(O)-PyO-κ2(O,N))(η1(N),μ(O)-PyO)(μ-O)Ti(ONep)2]2, [H][(PyO-κ2(O,N))(η1(O)-PyO)Ti(ONep)3], [(OR)2Zr(μ(O)-PyO-κ2(O,N))2(μ-OR)Zr(OR)3] (OR = OBut, ONep), [(OR)2Zr(μ(O,N)-PyO-κ2(O,N))2(μ(O,N)-PyO)Zr(OR)3] (OR = OBut, ONep), [[(OBut)2Zr(μ(O)-PyO-(κ2(N,O))(μ(O,N)-PyO)2Zr(OBut)](μ3-O)]2, [[(ONep)(PyO-κ2(N,O))Zr(μ(O,N)-PyO-κ2(N,O))2(μ(O)-PyO-κ2(N,O))Zr(ONep)](μ3-O)]2, [(OBut)(PyO-κ2(O,N))Zr(μ(O)-PyO-κ2(O,N))2((μ(O,N)-PyO)Zr(OBut)3], [(OBut)2Hf(μ(O)-PyO-κ2(N,O))2(μ-OBut)Hf(OBut)3], [(OR)2 M(μ(O)-PyO-κ2(N,O))2(μ(O,N)-PyO)M(OR)3] (OR = OBut, ONep), and [(ONep)3Hf(μ-ONep)(η1(N),μ(O)-PyO)]2Hf(ONep)2·tol. The structural diversity of the binding modes of the PyO led to a number of novel structure types in comparison to other pyridine alkoxy derivatives. The majority of

  3. Fast and selective ring-opening polymerizations by alkoxides and thioureas

    NASA Astrophysics Data System (ADS)

    Zhang, Xiangyi; Jones, Gavin O.; Hedrick, James L.; Waymouth, Robert M.

    2016-11-01

    Ring-opening polymerization of lactones is a versatile approach to generate well-defined functional polyesters. Typical ring-opening catalysts are subject to a trade-off between rate and selectivity. Here we describe an effective catalytic system combining alkoxides with thioureas that catalyses rapid and selective ring-opening polymerizations. Deprotonation of thioureas by sodium, potassium or imidazolium alkoxides generates a hydrogen-bonded alcohol adduct of the thiourea anion (thioimidate). The ring-opening polymerization of L-lactide mediated by these alcohol-bonded thioimidates yields highly isotactic polylactide with fast kinetics and living polymerization behaviour, as evidenced by narrow molecular weight distributions (Mw/Mn < 1.1), chain extension experiments and minimal transesterifications. Computational studies indicate a bifunctional catalytic mechanism whereby the thioimidate activates the carbonyl of the monomer and the alcohol initiator/chain end to effect the selective ring-opening of lactones and carbonates. The high selectivity of the catalyst towards monomer propagation over transesterification is attributed to a selective activation of monomer over polymer chains.

  4. 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.

  5. 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-Chen (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 percursor. 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.

  6. 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.

  7. Mesoporous Silica Films with Long-Range Order Prepared from Strongly Segregated Block Copolymer/Homopolymer Blend Templates

    SciTech Connect

    Tirumala, Vijay R.; Pai, Rajaram A.; Agarwal, Sumit; Testa, Jason J.; Bhatnagar, Gaurav; Romang, Alvin H.; Chandler, Curran; Gorman, Brian P.; Jones, Ronald L.; Lin, Eric K.; Watkins, James J.

    2008-06-30

    Well-ordered mesoporous silica films were prepared by infusion and selective condensation of Si alkoxides within preorganized block copolymer/homopolymer blend templates using supercritical CO{sub 2} as the delivery medium. The morphologies of the mesoporous silica films reflect significant improvements in the strength of segregation and long-range order of template blends of poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) triblock copolymers with selectively associating homopolymers such as poly(acrylic acid) or poly(4-hydroxystyrene) prior as compared to templates comprised of the neat copolymer. Control over film porosity, pore ordering, and morphology of the films is achieved through simple variations in the homopolymer concentration. The films were characterized using X-ray reflectivity, small-angle X-ray scattering, and transmission electron microscopy.

  8. 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

  9. 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.

  10. 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.

  11. 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

    2016-07-07

    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.

  12. 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

    2014-10-03

    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.

  13. Living polymerization of (o-(trimethylsilyl)phenyl)acetylene using `small alkoxide` molybdenum(VI) initiators

    SciTech Connect

    Schrock, R.R.; Luo, S.; Zanetti, N.C.; Fox, H.H.

    1994-09-01

    (o-(Trimethylsily)phenyl)acetylene (o-TM-SPA) is polymerized in a living manner by the new `small alkoxide` initiators Mo(CHCMe{sub 2}Ph)(N-1-adamantyl) [OCH(CF{sub 3}){sub 2}]{sub 2}(2,4-lutidine) (1b) and Mo(CHCMe{sub 2}-Ph)(NAr{prime})(OC{sub 6}F{sub 5}){sub 2}(quinulidine) (2; Ar{prime} = 2,6-C{sub 6}H{sub 3}Me{sub 2}) to give low-polydispersity polyenes containing up to 100 equiv of o-TMSPA. The thermodynamically most stable form of poly(o-TMSPA) that contains <25 double bonds is air-sensitive and has a significantly red-shifted {lambda}{sub max}. 29 refs., 1 fig., 1 tab.

  14. Radiophase development in hot-pressed alkoxide-derived titanate ceramics for nuclear waste stabilization

    SciTech Connect

    Dickson, F.J. ); Mitamura, H. ); White, T.J. )

    1989-06-01

    This paper reports phase development as a function of hot-pressing temperature studied in alkoxide-derived titanate-based ceramics doped with a 10 wt% loading of a sodium-rich (NAR) and a sodium-poor (NAP) simulated high-level waste. Pyrochlore was found to be the most abundant phase in both calcine powders. A pseudobrookite phase existed metastably at hot-pressing temperatures between 890{degrees} and 920{degrees} C. After hot-pressing at 1100{degrees} C, the final phase assemblage for the NAP material consisted of zirconolite, hollandite-type, perovskite, alloy, and reduced rutile (Magneli phases). In addition, NAR samples contained hibonite, freudenbergite, and loveringite. Phase development was driven to completion over a very narrow temperature range ({le}50{degrees} C), beginning at 870{degrees} and 850{degrees} C for NAP and NAR, respectively, although full densification was not achieved below 1100{degrees} C. Both waste forms exhibited comparable microstructure and aqueous durability.

  15. 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.

  16. 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)

  17. Three dimensional mesoporous silica strucutres with templated macropores

    NASA Astrophysics Data System (ADS)

    Kothari, Rohit; Hendricks, Nicholas R.; Watkins, James J.

    2013-03-01

    A novel approach to fabricate three dimensional macroporous structures comprised of mesoporous silica is demonstrated. Well-ordered mesoporous silica structures with macroporosity were obtained by using humidified supercritical carbon dioxide as a carrier medium to infuse and domain selectively condense silica alkoxide precursor in a microphase separated block copolymer/small molecule additive blend solution casted on macroporous supports such as cellulose filter paper and sponge. Subsequent calcination was used to remove both the block copolymer template and the macroporous support. Transition electron microscopy (TEM) and small angle x-ray diffraction (SAXD) confirmed the presence of well-ordered mesopores. Scanning electron microscopy confirmed faithful replication of the features of the macroporous supports. Physisorption showed BET surface areas as high as 400m2/g and the BJH pore size distributions obtained are in close agreement with the TEM and SAXD results. This dual scale porosity within the silica template will enhance overall transport and diffusion, which is appropriate for many applications including catalysis and sensing.

  18. Using bacterial cell growth to template catalytic asymmetry.

    PubMed

    Kaehr, Bryan; Brinker, C Jeffrey

    2010-08-07

    We report an approach to position gold nanoparticle catalysts for metal reduction asymmetrically on a biological template (E. coli) by exploiting the polarity of the bacterial cell envelope undergoing growth and division.

  19. E3 Charter Template

    EPA Pesticide Factsheets

    This is a charter template which includes decisions made during the project planning phase, as well as local project goals, a communication strategy, an outreach strategy, distribution of responsibilities and a schedule.

  20. 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

  1. 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.

  2. DNA-templated nickel nanostructures and protein assemblies.

    PubMed

    Becerril, Hector A; Ludtke, Paul; Willardson, Barry M; Woolley, Adam T

    2006-11-21

    We report a straightforward method for the fabrication of DNA-templated nickel nanostructures on surfaces. These nickel nanomaterials have potential to be applied as nanowires, as templated catalyst lines, as nanoscale magnetic domains, or in directed protein localization. Indeed, we show here that histidine-tagged phosducin-like protein (His-PhLP) binds with high selectivity to both Ni2+-treated surface DNA and DNA-templated nickel metal to create linear protein assemblies on surfaces. The association of His-PhLP with DNA-templated nickel ions or metal is reversible under appropriate rinsing conditions. Nanoscale DNA-templated protein assemblies might be useful in the construction of high-density protein lines for proteomic analysis, for example. Importantly, these nanofabrication procedures are not limited to linear DNA and can be applied readily to other self-assembled DNA topologies.

  3. Different mechanisms at different temperatures for the ring-opening polymerization of lactide catalyzed by binuclear magnesium and zinc alkoxides.

    PubMed

    Sun, Yangyang; Cui, Yaqin; Xiong, Jiao; Dai, Zhongran; Tang, Ning; Wu, Jincai

    2015-10-07

    Two binuclear magnesium and zinc alkoxides supported by a bis-salalen type dinucleating heptadentate Schiff base ligand were synthesized and fully characterized. The two complexes are efficient initiators for the ring-opening polymerization (ROP) of L-lactide, affording polymers with narrow polydispersities and desirable molecular weights. Interestingly, the mechanisms for the ROP of lactide are different at different temperatures. At a high temperature of 130 °C, a coordination-insertion mechanism is reasonable for the bulk melt polymerization of lactide. At a low temperature, the alkoxide cannot initiate the ROP reaction; however, upon the addition of external benzyl alcohol into the system, the ROP of lactide can smoothly proceed via an "activated monomer" mechanism. In addition, these complexes display slight stereo-selectivity for the ring-opening polymerization of rac-lactide, affording partially isotactic polylactide in toluene with a Pm value of 0.59.

  4. Optimizing ultrathin Ag films for high performance oxide-metal-oxide flexible transparent electrodes through surface energy modulation and template-stripping procedures

    NASA Astrophysics Data System (ADS)

    Yang, Xi; Gao, Pingqi; Yang, Zhenhai; Zhu, Juye; Huang, Feng; Ye, Jichun

    2017-03-01

    Among new flexible transparent conductive electrode (TCE) candidates, ultrathin Ag film (UTAF) is attractive for its extremely low resistance and relatively high transparency. However, the performances of UTAF based TCEs critically depend on the threshold thickness for growth of continuous Ag films and the film morphologies. Here, we demonstrate that these two parameters could be strongly altered through the modulation of substrate surface energy. By minimizing the surface energy difference between the Ag film and substrate, a 9 nm UTAF with a sheet resistance down to 6.9 Ω sq‑1 can be obtained using an electron-beam evaporation process. The resultant UTAF is completely continuous and exhibits smoother morphologies and smaller optical absorbances in comparison to the counterpart of granular-type Ag film at the same thickness without surface modulation. Template-stripping procedure is further developed to transfer the UTAFs to flexible polymer matrixes and construct Al2O3/Ag/MoOx (AAM) electrodes with excellent surface morphology as well as optical and electronic characteristics, including a root-mean-square roughness below 0.21 nm, a transparency up to 93.85% at 550 nm and a sheet resistance as low as 7.39 Ω sq‑1. These AAM based electrodes also show superiority in mechanical robustness, thermal oxidation stability and shape memory property.

  5. Optimizing ultrathin Ag films for high performance oxide-metal-oxide flexible transparent electrodes through surface energy modulation and template-stripping procedures

    PubMed Central

    Yang, Xi; Gao, Pingqi; Yang, Zhenhai; Zhu, Juye; Huang, Feng; Ye, Jichun

    2017-01-01

    Among new flexible transparent conductive electrode (TCE) candidates, ultrathin Ag film (UTAF) is attractive for its extremely low resistance and relatively high transparency. However, the performances of UTAF based TCEs critically depend on the threshold thickness for growth of continuous Ag films and the film morphologies. Here, we demonstrate that these two parameters could be strongly altered through the modulation of substrate surface energy. By minimizing the surface energy difference between the Ag film and substrate, a 9 nm UTAF with a sheet resistance down to 6.9 Ω sq−1 can be obtained using an electron-beam evaporation process. The resultant UTAF is completely continuous and exhibits smoother morphologies and smaller optical absorbances in comparison to the counterpart of granular-type Ag film at the same thickness without surface modulation. Template-stripping procedure is further developed to transfer the UTAFs to flexible polymer matrixes and construct Al2O3/Ag/MoOx (AAM) electrodes with excellent surface morphology as well as optical and electronic characteristics, including a root-mean-square roughness below 0.21 nm, a transparency up to 93.85% at 550 nm and a sheet resistance as low as 7.39 Ω sq−1. These AAM based electrodes also show superiority in mechanical robustness, thermal oxidation stability and shape memory property. PMID:28291229

  6. Optimizing ultrathin Ag films for high performance oxide-metal-oxide flexible transparent electrodes through surface energy modulation and template-stripping procedures.

    PubMed

    Yang, Xi; Gao, Pingqi; Yang, Zhenhai; Zhu, Juye; Huang, Feng; Ye, Jichun

    2017-03-14

    Among new flexible transparent conductive electrode (TCE) candidates, ultrathin Ag film (UTAF) is attractive for its extremely low resistance and relatively high transparency. However, the performances of UTAF based TCEs critically depend on the threshold thickness for growth of continuous Ag films and the film morphologies. Here, we demonstrate that these two parameters could be strongly altered through the modulation of substrate surface energy. By minimizing the surface energy difference between the Ag film and substrate, a 9 nm UTAF with a sheet resistance down to 6.9 Ω sq(-1) can be obtained using an electron-beam evaporation process. The resultant UTAF is completely continuous and exhibits smoother morphologies and smaller optical absorbances in comparison to the counterpart of granular-type Ag film at the same thickness without surface modulation. Template-stripping procedure is further developed to transfer the UTAFs to flexible polymer matrixes and construct Al2O3/Ag/MoOx (AAM) electrodes with excellent surface morphology as well as optical and electronic characteristics, including a root-mean-square roughness below 0.21 nm, a transparency up to 93.85% at 550 nm and a sheet resistance as low as 7.39 Ω sq(-1). These AAM based electrodes also show superiority in mechanical robustness, thermal oxidation stability and shape memory property.

  7. Synthesis of metal oxide nanoparticles (CuO and ZnO NPs) via biological template and their optical sensor applications

    NASA Astrophysics Data System (ADS)

    Maruthupandy, Muthuchamy; Zuo, Yong; Chen, Jing-Shuai; Song, Ji-Ming; Niu, He-Lin; Mao, Chang-Jie; Zhang, Sheng-Yi; Shen, Yu-Hua

    2017-03-01

    The present study is focused on employing Camellia japonica leaf extract as inductive and stabilizing agent to synthesis CuO and ZnO nanoparticles (NPs). The chemicals, such as (Cu(NO3)2·3H2O) and (Zn(NO3)2·6H2O) were converted into copper and zinc ions, respectively because of the different natural products present in the C. japonica leaf extract. The UV-vis spectra of CuO and ZnO NPs showed absorption peak at 290 nm and 301 nm, respectively. The XRD result revealed crystalline nature of the metal oxide NPs and the TEM images indicated that average sizes of the synthesized CuO and ZnO NPs were ∼17 nm and ∼20 nm, respectively. The FTIR spectra of C. japonica leaf extract showed the presence of organic groups, such as, sbnd OH, sbnd Csbnd N, and N-H, which would be responsible for forming CuO and ZnO NPs. The synthesized CuO and ZnO NPs were tested for the optical sensing of metal ions, viz. Li+ and Ag+ that illustrated excellent outcome and hence this method offers a novel lane for the synthesis of metal oxide NPs, which can be used as optical sensor for the detection of metal ions.

  8. 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.

  9. 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.

  10. Molecular Level Coating of Metal Oxide Particles

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

    Polymer encapsulated metal oxide particles are prepared by combining a polyamide acid in a polar osmotic 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.

  11. A Pyridine Alkoxide Chelate Ligand That Promotes Both Unusually High Oxidation States and Water-Oxidation Catalysis.

    PubMed

    Michaelos, Thoe K; Shopov, Dimitar Y; Sinha, Shashi Bhushan; Sharninghausen, Liam S; Fisher, Katherine J; Lant, Hannah M C; Crabtree, Robert H; Brudvig, Gary W

    2017-03-08

    Water-oxidation catalysis is a critical bottleneck in the direct generation of solar fuels by artificial photosynthesis. Catalytic oxidation of difficult substrates such as water requires harsh conditions, so the ligand must be designed both to stabilize high oxidation states of the metal center and to strenuously resist ligand degradation. Typical ligand choices either lack sufficient electron donor power or fail to stand up to the oxidizing conditions. Our research on Ir-based water-oxidation catalysts (WOCs) has led us to identify a ligand, 2-(2'-pyridyl)-2-propanoate or "pyalk", that fulfills these requirements. Work with a family of Cp*Ir(chelate)Cl complexes had indicated that the pyalk-containing precursor gave the most robust WOC, which was still molecular in nature but lost the Cp* fragment by oxidative degradation. In trying to characterize the resulting active "blue solution" WOC, we were able to identify a diiridium(IV)-mono-μ-oxo core but were stymied by the extensive geometrical isomerism and coordinative variability. By moving to a family of monomeric complexes [Ir(III/IV)(pyalk)3] and [Ir(III/IV)(pyalk)2Cl2], we were able to better understand the original WOC and identify the special properties of the ligand. In this Account, we cover some results using the pyalk ligand and indicate the main features that make it particularly suitable as a ligand for oxidation catalysis. The alkoxide group of pyalk allows for proton-coupled electron transfer (PCET) and its strong σ- and π-donor power strongly favors attainment of exceptionally high oxidation states. The aromatic pyridine ring with its methyl-protected benzylic position provides strong binding and degradation resistance during catalytic turnover. Furthermore, the ligand has two additional benefits: broad solubility in aqueous and nonaqueous solvents and an anisotropic ligand field that enhances the geometry-dependent redox properties of its complexes. After discussion of the general properties, we

  12. 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.

  13. The Investigation of Intermediate Stage of Template Etching with Metal Droplets by Wetting Angle Analysis on (001) GaAs Surface.

    PubMed

    Lyamkina, A A; Dmitriev, D V; Galitsyn, Yu G; Kesler, V G; Moshchenko, S P; Toropov, A I

    2011-12-01

    In this work, we study metal droplets on a semiconductor surface that are the initial stage for both droplet epitaxy and local droplet etching. The distributions of droplet geometrical parameters such as height, radius and volume help to understand the droplet formation that strongly influences subsequent nanohole etching. To investigate the etching and intermixing processes, we offer a new method of wetting angle analysis. The aspect ratio that is defined as the ratio of the height to radius was used as an estimation of wetting angle which depends on the droplet material. The investigation of the wetting angle and the estimation of indium content revealed significant materials intermixing during the deposition time. AFM measurements reveal the presence of two droplet groups that is in agreement with nanohole investigations. To explain this observation, we consider arsenic evaporation and consequent change in the initial substrate. On the basis of our analysis, we suggest the model of droplet evolution and the formation of two droplet groups.

  14. 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.

  15. 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.

  16. 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.

  17. Template engaged synthesis of hollow ceria-based composites

    NASA Astrophysics Data System (ADS)

    Chen, Guozhu; Rosei, Federico; Ma, Dongling

    2015-03-01

    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.

  18. 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.

  19. 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

    2016-06-06

    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

  20. 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.

  1. 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

    2015-04-06

    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

  2. Effects of alkoxide addition on the electrochemical deposition and dissolution in triglyme-based solution dissolving magnesium bis(trifluoromethanesulfonyl)amide

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    Electrochemical deposition and dissolution of magnesium (Mg) has been examined in triethylene glycol dimethyl ether (triglyme, G3) dissolving magnesium bis(triflouromethanesulfonyl)amide, Mg(TFSA)2. The voltammetric current responses at platinum (Pt) electrode in the G3-based electrolytes revealed that the Mg deposition/dissolution process depends on the Mg species in the solution phase. The addition of alkoxides, Mg(OCnH2n+1)2, was effective on the reversibility of the process in Mg(TFSA)2/G3. Higher anodic current corresponding to the electrochemical dissolution was observed in the electrolyte solution containing Mg(OC2H5)2 as the additive. The morphology of the Mg deposition at the Pt substrate also depended on the additive Mg-alkoxides. The resulting Mg(TFSA)2/G3 solutions containing Mg-alkoxides were found to be a possible electrolyte system for rechargeable Mg battery operating at ambient temperature.

  3. 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.

  4. Templated Electrodeposition of Highly Porous Nanostructured Materials

    NASA Astrophysics Data System (ADS)

    Yang, Han-Chang; Lim, Stephanie; Liu, Jiabin; Wu, Qian; Cheng, X. M.

    2011-03-01

    The fabrication of nanoporous materials has been of great interest for applications such as biosensors, photonic materials and energy storage. Compared to many other methods, the templated electrodeposition method is low cost, fast, and compatible with large-scale production. In this work, we developed a templated electrochemical deposition technique for fabricating highly ordered and highly porous nanostructured materials. The fabrication involves the following steps: self-assembly of monodispersed polystyrene spheres, electrochemical deposition of the desired materials, and sphere removal by a dissolution process. Deposition of Au and Ni layered metallic nanoporous structures were studied using different electrolytes at appropriate potentials. The pore size of the materials was tuned by using different sizes of template polystyrene spheres ranging from 50nm to 1000nm. Scanning electron microscopy images confirmed the highly ordered 3-dimensional hexagonal closed pack (hcp) structures in the samples. The templated electrochemical deposition technique provides a promising alternative approach to preparing highly porous anode materials for battery applications. Work supported by Bryn Mawr K/G fund for faculty research.

  5. 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.

  6. 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.

  7. 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.

  8. Fabrication and characterization of Sb-doped Sn02 thin films derived from methacrylic acid modified tin(IV)alkoxides

    NASA Astrophysics Data System (ADS)

    Kololuoma, Terho K.; Tolonen, Ari; Johansson, Leena-Sisko; Campbell, Joseph M.; Karkkainen, Ari H. O.; Hiltunen, Marianne; Haatainen, Tomi; Rantala, Juha T.

    2002-10-01

    We report on the fabrication of transparent, conductive and directly photopatternable, pure and Sb-doped tin dioxide thin films. Precursors used were antimony(III)isopropoxide and a photo-reactive tin alkoxide synthesized from tin(IV)isopropoxide and methacrylic acid. The synthesis of methacrylic acid modified tin alkoxide was monitored in-situ using IR- and ESI-TOF mass spectroscopic techniques. Sb-doped organo-tin films were deposited via single layer spin coating. After deposition the films were patterned via photopolymerization, using a mercury I-line UV-lamp. All investigated materials could be patterned with 3 μm features. After development in isopropanol, the films were annealed in air, in order to obtain crystalline and conductive films. The electrical conductivities of the annealed thin films with, and without, UV-irradiation were determined using a linear four-point method. The direct photopatterning process was found to increase the film conductivity for all the Sb-doping levels tested. The mechanisms for the increased conductivity were characterized using AFM, XPS and XRD techniques.

  9. Effect of CaTiO(3)-CaCO(3) prepared by alkoxide method on cell response.

    PubMed

    Rodriguez, Andrea P; Inoue, Miho; Tanaka, Toshiyuki; Miyake, Michihiro; Sfer, Ana M; Kishimoto, Etsuo; Tsujigiwa, Hidetsugu; Rivera, Rosario S; Nagatsuka, Hitoshi

    2010-04-01

    In recent years, calcium titanate (CaTiO(3)) and carbon-containing materials have gained much attention in a number of biomedical material researches. To maximize the advantages of both materials, we developed a novel alkoxide method to get "calcium titanate with calcium carbonate" (CaTiO(3)-CaCO(3)). The objective was to evaluate the crystallinity and elemental composition of CaTiO(3)-CaCO(3) prepared by alkoxide method, CaTiO(3)-aC elaborated by modified thermal decomposition method, commercially-prepared CaTiO(3), and the effect of these materials on the bone marrow stromal cell. Hydroxyapatite was used as positive control material. We examined the cellular proliferation, osteoblastic differentiation, and mineralization of KUSA/A1 cells cultured with the materials. The results showed that CaTiO(3)-CaCO(3) and CaTiO(3)-aC contained evidence of calcium carbonate enhancing cell proliferation, osteoblastic differentiation, and mineralization. On the contrary, the commercially-prepared CaTiO(3) revealed absence of calcium carbonate with lower cell response than the other groups. The results indicated that calcium carbonate could play a key role in the cell response of CaTiO(3) material. In conclusion, our findings suggest that CaTiO(3)-CaCO(3) could be considered an important candidate as a biomaterial for medical and dental applications.

  10. Organically modified silicas on metal nanowires.

    PubMed

    Dean, Stacey L; Stapleton, Joshua J; Keating, Christine D

    2010-09-21

    Organically modified silica coatings were prepared on metal nanowires using a variety of silicon alkoxides with different functional groups (i.e., carboxyl groups, polyethylene oxide, cyano, dihydroimidazole, and hexyl linkers). Organically modified silicas were deposited onto the surface of 6-μm-long, ∼300-nm-wide, cylindrical metal nanowires in suspension by the hydrolysis and polycondensation of silicon alkoxides. Syntheses were performed at several ratios of tetraethoxysilane to an organically modified silicon alkoxide to incorporate desired functional groups into thin organosilica shells on the nanowires. These coatings were characterized using transmission electron microscopy, X-ray photoelectron spectroscopy, and infrared spectroscopy. All of the organically modified silicas prepared here were sufficiently porous to allow the removal of the metal nanowire cores by acid etching to form organically modified silica nanotubes. Additional functionality provided to the modified silicas as compared to unmodified silica prepared using only tetraethoxysilane precursors was demonstrated by chromate adsorption on imidazole-containing silicas and resistance to protein adsorption on polyethyleneoxide-containing silicas. Organically modified silica coatings on nanowires and other nano- and microparticles have potential application in fields such as biosensing or nanoscale therapeutics due to the enhanced properties of the silica coatings, for example, the prevention of biofouling.

  11. 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

  12. 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.

  13. Homoepitaxial growth of MOD-YBCO thick films on evaporated and MOD templates

    NASA Astrophysics Data System (ADS)

    Tanabe, D.; Yamaguchi, I.; Sohma, M.; Tsukada, K.; Matsui, M.; Kumagai, T.; Manabe, T.

    2011-11-01

    We have prepared metal organic deposition (MOD)-YBCO thick films by repeating the coating-pyrolysis-crystallization procedure onto ∼100-nm-thick evaporated and MOD templates. Surface morphology of the template was found to strongly affect the homoepitaxial growth of MOD-YBCO layers on the template; namely, the epitaxial growth of MOD-YBCO on the evaporated template was much easier than that on the MOD template. A 220-nm-thick epitaxial MOD-YBCO film was successfully prepared on the 100-nm-thick evaporated-YBCO template to obtain a 320-nm-thick YBCO film, which exhibited Jc = 2.44 MA/cm2 and Ic = 78 A/cm. The Ic value has significantly increased from 37 A/cm for the evaporated-template.

  14. Ordered Nanomaterials Thin Films via Supported Anodized Alumina Templates

    NASA Astrophysics Data System (ADS)

    Es-Souni, Mohammed; Habouti, Salah

    2014-10-01

    Supported anodized alumina template films with highly ordered porosity are best suited for fabricating large area ordered nanostructures with tunable dimensions and aspect ratios. In this paper we first discuss important issues for the generation of such templates, including required properties of the Al/Ti/Au/Ti thin film heterostructure on a substrate for high quality templates. We then show examples of anisotropic nanostructure films consisting of noble metals using these templates, discuss briefly their optical properties and their applications to molecular detection using surface enhanced Raman spectroscopy. Finally we briefly address the possibility to make nanocomposite films, exemplary shown on a plasmonic-thermochromic nanocomposite of VO2-capped Au-nanorods.

  15. DNA-templated nanofabrication.

    PubMed

    Becerril, Héctor A; Woolley, Adam T

    2009-02-01

    Nanofabrication, or the organizational control over matter at the nanometre scale, is an intriguing scientific challenge requiring multidisciplinary tools for its solution. DNA is a biomolecule that can be combined with other nanometre-scale entities through chemical self-assembly to form a broad variety of nanomaterials. In this tutorial review we present the principles that allow DNA to interact with other chemical species, and describe the challenges and potential applications of DNA as a template for making both biological and inorganic features with nanometre resolution. As such, this report should be of interest to chemists, surface and materials scientists, biologists, and nanotechnologists, as well as others who seek to use DNA in nanofabrication.

  16. Templated quasicrystalline molecular layers

    NASA Astrophysics Data System (ADS)

    Smerdon, Joe; Young, Kirsty; Lowe, Michael; Hars, Sanger; Yadav, Thakur; Hesp, David; Dhanak, Vinod; Tsai, An-Pang; Sharma, Hem Raj; McGrath, Ronan

    2014-03-01

    Quasicrystals are materials with long range ordering but no periodicity. We report scanning tunneling microscopy (STM) observations of quasicrystalline molecular layers on five-fold quasicrystal surfaces. The molecules adopt positions and orientations on the surface consistent with the quasicrystalline ordering of the substrate. Carbon-60 adsorbs atop sufficiently-separated Fe atoms on icosahedral Al-Cu-Fe to form a unique quasicrystalline lattice whereas further C60 molecules decorate remaining surface Fe atoms in a quasi-degenerate fashion. Pentacene (Pn) adsorbs at tenfold-symmetric points around surface-bisected rhombic triacontahedral clusters in icosahedral Ag-In-Yb. These systems constitute the first demonstrations of quasicrystalline molecular ordering on a template. EPSRC EP/D05253X/1, EP/D071828/1, UK BIS.

  17. 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).

  18. A Template for Insect Cryopreservation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This article is intended to update the reader on the progress made on insect embryo cryopreservation in the past 20 years and gives information for developing a protocol for cryopreserving insects by using a 2001 study as a template. The study used for the template is the cryopreservation of the Old...

  19. Silver nanowires--unique templates for functional nanostructures.

    PubMed

    Sun, Yugang

    2010-09-01

    This feature article reviews the synthesis and application of silver nanowires with the focus on a polyol process that is capable of producing high quality silver nanowires with high yield. The as-synthesized silver nanowires can be used as both physical templates for the synthesis of metal/dielectric core/shell nanowires and chemical templates for the synthesis of metal nanotubes as well as semiconductor nanowires. Typical examples including Ag/SiO(2) coaxial nanocables, single- and multiple-walled nanotubes made of Au-Ag alloy, AgCl nanowires and AgCl/Au core/shell nanowires are discussed in detail to illustrate the versatility of nanostructures derived from silver nanowire templates. Novel properties associated with these one-dimensional nanostructures are also briefly discussed to shed the light on their potential applications in electronics, photonics, optoelectronics, catalysis, and medicine.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  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. Metal oxide porous ceramic membranes with small pore sizes

    DOEpatents

    Anderson, Marc A.; Xu, Qunyin

    1991-01-01

    A method is disclosed for the production of metal oxide ceramic membranes of very small pore size. The process is particularly useful in the creation of titanium and other transition metal oxide membranes. The method utilizes a sol-gel process in which the rate of particle formation is controlled by substituting a relatively large alcohol in the metal alkoxide and by limiting the available water. Stable, transparent metal oxide ceramic membranes are created having a narrow distribution of pore size, with the pore diameter being manipulable in the range of 5 to 40 Angstroms.

  7. Metal oxide porous ceramic membranes with small pore sizes

    DOEpatents

    Anderson, Marc A.; Xu, Qunyin

    1992-01-01

    A method is disclosed for the production of metal oxide ceramic membranes of very small pore size. The process is particularly useful in the creation of titanium and other transition metal oxide membranes. The method utilizes a sol-gel process in which the rate of particle formation is controlled by substituting a relatively large alcohol in the metal alkoxide and by limiting the available water. Stable, transparent metal oxide ceramic membranes are created having a narrow distribution of pore size, with the pore diameter being manipulable in the range of 5 to 40 Angstroms.

  8. 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.

  9. 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.

  10. Template Synthesis of Carbon Nanotubules

    NASA Astrophysics Data System (ADS)

    Tee, J. C.; Sanip, S. M.; Aziz, M.; Ismail, A. F.

    2010-03-01

    The template synthesis of carbon nanostructures formed in porous anodic aluminium oxide (AAO) template with a pore size of 200 nm by a liquid phase impregnation of the template with a polymer, polyfurfuryl alcohol, followed by carbonization is studied. The temperatures of exposure to furfuryl alcohol vapour were varied between 50 and 70° C. The resultant carbon nanotubules formed were hollow with open ends having diameter ranging from 220-300 nm which is in agreement with the pore size of the template used. The BET surface area was found to increase from 11.64 m2/g before pyrolysis to 90.19 m2/g after pyrolysis as a result of the formation of carbon nanotubules.

  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. Magnetic and conductive magnetite nanowires by DNA-templating.

    PubMed

    Mohamed, Hasan Daw A; Watson, Scott M D; Horrocks, Benjamin R; Houlton, Andrew

    2012-09-28

    The synthesis of nanowires made of magnetite (Fe(3)O(4)) phase iron oxide was achieved using DNA as a template to direct formation of the metal oxide and confine its growth in two dimensions. This simple solution-based approach involves initial association of Fe(2+) and Fe(3+) to the DNA "template" molecules, and subsequent co-precipitation of the Fe(3)O(4) material, upon increasing the solution pH, to give the final metal oxide nanowires. Analysis of the DNA-templated material, using a combination of FTIR, XRD, XPS, and Raman spectroscopy, confirmed the iron oxide formed to be the Fe(3)O(4) crystal phase. Investigation of the structural character of the nanowires, carried out by AFM, revealed the metal oxide to form regular coatings of nanometre-scale thickness around the DNA templates. Statistical analysis showed the size distribution of the nanowires to follow a trimodal model, with the modal diameter values identified as 5-6 nm, 14-15 nm, and 23-24 nm. Additional scanning probe microscopy techniques (SCM, MFM) were also used to verify that the nanowire structures are electrically conducting and exhibit magnetic behaviour. Such properties, coupled with the small dimensions of these materials, make them potentially good candidates for application in a host of future nanoscale device technologies.

  13. An alkoxide cluster with 18 Li+ ions encapsulating two borate anions, [((t)BuO)12Li18(BO3)2].

    PubMed

    Tombul, Mustafa; Errington, R John; Coxall, Robert A; Clegg, William

    2003-06-01

    The title compound, bis(borato)dodeca(tert-butoxo)octadecalithium, [Li(18)(BO(3))(2)(C(4)H(9)O)(12)], is formulated conveniently as [(((t)BuOLi)(3)(Li(3)BO(3)))(2)((t)BuOLi)(6)]. A central 12-membered ring and two outer six-membered rings are formed by alternating Li(+) cations and alkoxide O atoms. Sandwiched between the central ring and each of the outer rings is a planar array of three further Li(+) cations surrounding a [BO(3)](3-) anion. Thus, the molecule consists of a cationic [Li(18)(O(t)Bu)(12)](6+) cage encapsulating two borate anions. This compound is the first example of a structurally characterized polynuclear lithium borate, and a rare case of a lithium alkoxide cage with nuclearity greater than eight. All the alkoxide ligands are triply bridging, and the lithium ions have trigonal-planar, trigonal-pyramidal and fourfold coordination, all with major distortions from regular coordination geometry.

  14. 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.

  15. Influence of water/alkoxide ratio in the synthesis of nanosized sol-gel titania on the release of phenytoin.

    PubMed

    López, T; Espinoza, K A; Kozina, A; Castillo, P; Silvestre-Albero, A; Rodriguez-Reinoso, F; Alexander-Katz, R

    2011-04-05

    The sol-gel method was used to synthesize inorganic reservoirs with encapsulated antiepileptic drug phenytoin. The drug release profile was shown to depend on the morphology and surface properties of the matrix. A parameter of the synthesis such as water/alkoxide ratio r(w) was varied in order to investigate its influence on the matrix properties and as a result on the drug release profile. It was found that the specific surface area and crystallization degree decrease with an increase of r(w), whereas the hydroxyl group coverage increases with an increase of r(w). Drug release kinetics studies revealed that the initial release rate increases with an increase of water content in the reaction, whereas the long time release rate first slightly increases with an increase of water content from 4 to 8 and then decreases for r(w) = 16. The interplay of different parameters of the matrix is shown to be responsible for such a dependence and is discussed in the Article.

  16. 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

    2016-01-04

    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.

  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. 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

    2013-09-03

    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.

  19. Large-scale ultraflat nanopatterned surfaces without template residues.

    PubMed

    Jung, Bongsu; Frey, Wolfgang

    2008-04-09

    Ultraflat surfaces are required for many studies of single molecules, and the need for both a wide choice of surface materials and the ability to pattern these surfaces has led to the development of different template-stripping approaches. The fabrication of nanopatterned ultraflat surfaces is particularly challenging, because more than one material is present in the surface. We demonstrate a new template-stripping strategy that allows us to fabricate large-area nanopatterned surfaces, solving the problem of incomplete template removal by introducing a sacrificial carbon layer and a sandwich structure for the template. The thin residual carbon film transferred from the template is removed from the nanopatterned surface by dry etching, as demonstrated by x-ray photoelectron spectroscopy and, for metal nanoparticles embedded in a glass surface, by a shift in the absorption of the localized surface plasmon resonance. We show that gold nanoparticles in a glass surface can be selectively functionalized with thiols yielding about 2 nm height increase. Atomic force microscopy and localized surface plasmon resonance spectroscopy both indicate that the nanoparticle shape is preserved well.

  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. 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.

  2. Template polymerization of nucleotide analogues

    NASA Technical Reports Server (NTRS)

    Orgel, L. E.

    1991-01-01

    Recent work on the template-directed reactions of the natural D-nucleotides has made it clear that l-nucleotides and nucleotide-like derivatives of other sugars would strongly inhibit the formation of long oligonucleotides. Consequently, attention is focusing on molecules simpler than nucleotides that might have acted as monomers of an information transfer system. We have begun a general exploration of the template directed reactions of diverse peptide analogues. I will present work by Dr. Taifeng Wu on oxidative oligomerization of phosphorothioates and of Dr. Mary Tohidi on the cyclic polymerization of nucleoside and related cyclic pyrophosphates.

  3. 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.

  4. 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.

  5. 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.

  6. Progress of NIL template making

    NASA Astrophysics Data System (ADS)

    Yusa, Satoshi; Hiraka, Takaaki; Kobiki, Ayumi; Sasaki, Shiho; Itoh, Kimio; Toyama, Nobuhito; Kurihara, Masaaki; Mohri, Hiroshi; Hayashi, Naoya

    2007-05-01

    Nano-imprint lithography (NIL) has been counted as one of the lithography solutions for hp32nm node and beyond. Recently, the small line edge roughness (LER) as well as the potentially high resolution that will ensure no-OPC mask feature is attracting many researchers. The template making is one of the most critical issues for the realization of NIL. Especially when we think of a practical template fabrication process on a 65mm square format that is going to be the industry standard, the resolution of the template making process showed a limitation. We have achieved for the first time an hp22nm resolution on the 65nm template format. Both line and space patterns and hole patterns were well resolved. Regarding dot patterns, we still need improvement, but we have achieved resolution down to hp28nm. Although so far we cannot achieve these resolution limits of various pattern category at the same time on one substrate, an intermediate process condition showed sufficient uniformity both in lateral CD and in vertical depth. Global pattern image placement also showed sufficient numbers at this stage of lithography development. A 20nm feature (with a pitch of 80nm) showed sufficient imprint result.

  7. Cyclic polyvanadates incorporating template transition metal cationic species: synthesis and structures of hexavanadate [PdV6O18]4-, octavanadate [Cu2V8O24]4-, and decavanadate [Ni4V10O30(OH)2(H2O)6]4-.

    PubMed

    Kurata, Taisei; Uehara, Akira; Hayashi, Yoshihito; Isobe, Kiyoshi

    2005-04-04

    Three types of heteropolyvanadates, [(C2H5)4N]4[PdV6O18] (1), [(C2H5)4N]4[Cu2V8O24] (2), and [(C6H5)4P]4[Ni4V10O30(OH)2(H2O)6] (3), were synthesized through the reaction between the [VO3]- anion and metal template cations of Pd(II), Cu(II), and Ni(II). The X-ray crystal structures of 1 (a = 29.952(4) A, b = 12.911(2) A, and c = 13.678(2) A, orthorhombic, space group Pca2(1) with Z = 4), 2 (a = 13.740(1) A, b = 22.488(2) A, c = 18.505(2) A, and beta= 94.058(2) degrees , monoclinic, space group P2(1)/n with Z = 4), and 3 (a = 12.333(2) A, b = 16.208(4) A, c = 16.516(3) A, alpha = 112.438(3) degrees , beta = 94.735(3) degrees , and gamma = 104.749(3) degrees , triclinic, space group P with Z = 1) demonstrate that the metal cationic species induced cyclic [VO3](n-)n (n = 6, 8, 10) ring formation and the cations are incorporated in the rings themselves. In the metal inclusion products, the cyclic vanadates act as macrocyclic ligands, in which the metal cationic species act as the templates. The cyclic vanadate is composed of tetrahedral VO4 units that share corners and incorporates a metal cationic species in the center of the molecules. The bowl-shaped complex 1 includes a Pd2+ cation that is coordinated by the oxygen donors of a boatlike hexavanadate ring. The diamagnetic complex 1 was characterized via 51V and 17O NMR spectroscopy. Complex 2 involves an octavanadate ring and two Cu2+, which are located on both sides of the mean plane as defined by the eight oxygen atoms that bridge the vanadium atoms. In the case of complex 3, the di-mu-hydroxo-bridged Ni2+ dimer with capped Ni2+ aqua ions is formed by hydrolysis to form the decavanadate ring, in which two of the tetrahedral vanadate units are not bonded to the Ni2+ core but supported by hydrogen bonds through the aqua-ligand in the capped Ni2+ cation. Complexes 1-3 in solution were clearly identified by their characteristic isotope patterns using ESI-MS studies.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. Fumigant Management Plan - Phase 1 Templates

    EPA Pesticide Factsheets

    FMPs are required by pesticide labels, so EPA provides chemical-specific soil fumigant templates and samples in PDF and Word formats. Choose the appropriate template for products containing chloropicrin, dazomet, metam sodium/potassium, or methyl bromide.

  13. Transforming surgery through biomaterial template technology.

    PubMed

    Hodde, Jason; Hiles, Michael

    2016-03-01

    Templates inserted into surgical wounds strongly influence the healing responses in humans. The science of these templates, in the form of extracellular matrix biomaterials, is rapidly evolving and improving as the natural interactions with the body become better understood.

  14. Preparation, structural, and calorimetric characterization of bicomponent metallic photonic crystals

    NASA Astrophysics Data System (ADS)

    Kozlov, M. E.; Murthy, N. S.; Udod, I.; Khayrullin, I. I.; Baughman, R. H.; Zakhidov, A. A.

    2007-03-01

    We report preparation and characterization of novel bicomponent metal-based photonic crystals having submicron three-dimensional (3D) periodicity. Fabricated photonic crystals include SiO2 sphere lattices infiltrated interstitially with metals, carbon inverse lattices filled with metal or metal alloy spheres, Sb inverse lattices, and Sb inverse lattices filled with Bi spheres. Starting from a face centered SiO2 lattice template, these materials were obtained by sequences of either templating and template extraction or templating, template extraction, and retemplating. Surprising high fidelity was obtained for all templating and template extraction steps. Scanning electron microscopy (SEM), small angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC) were used to characterize the structure and the effects of the structure on calorimetric properties. To the best of our knowledge, SAXS data on metallic photonic crystals were collected for first time.

  15. Plasmonic nanodot array optimization on organic thin film solar cells using anodic aluminum oxide templates

    NASA Astrophysics Data System (ADS)

    Bae, Kyuyoung; Kim, Kyoungsik

    2013-09-01

    The fabrication method of plasmonic nanodots on ITO or nc-ZnO substrate has been developed to improve the efficiency of organic thin film solar cells. Nanoscale metallic nanodots arrays are fabricated by anodic aluminum oxide (AAO) template mask which can have different structural parameters by varying anodization conditions. In this paper, the structural parameters of metallic nanodots, which can be controlled by the diverse structures of AAO template mask, are investigated to enhance the optical properties of organic thin film solar cells. It is found that optical properties of the organic thin film solar cells are improved by finding optimization values of the structural parameters of the metallic nanodot array.

  16. Nanorings of self-assembled fullerene C(70) as templating nanoreactors.

    PubMed

    Iyer, K Swaminathan; Saunders, Martin; Becker, Thomas; Evans, Cameron W; Raston, Colin L

    2009-11-18

    Micelles, polyelectrolytes, peptides, and plasmid DNA with well-defined growth cavities can function as templates for the synthesis of metal nanocrystals. In a similar way, carbon-based toroidal 'nanoreactors' composed of clustered fullerenes could be used to synthesize nanohybrids by forming metal nanocrystals within the confines of the ring.

  17. Rigid templating of high surface-area, mesoporous, nanocrystalline rutile using a polyether block amide copolymer template.

    PubMed

    Jiang, Xingmao; Brinker, C Jeffrey

    2010-09-07

    Highly crystalline rutile with a specific surface area as high as 280 m(2) g(-1) and well-connected uniform mesoporosity has been synthesized by rigid templating using commercial, low-cost polyether block amide. This general, simple synthesis route for high surface-area mesoporous nanocrystalline oxides and nanocomposite membranes is important for catalysis, sensors, energy storage, solar cells, heavy metal removal and separations.

  18. (Ligand intermediates in metal-catalyzed reactions)

    SciTech Connect

    Not Available

    1992-01-01

    This report consists of sections on sigma bond complexes of alkenes, a new carbon-hydrogen bond activation reaction of alkene complexes, carbon-hydrogen bond migrations in alkylidene complexes, carbon- hydrogen bond migrations in alkyne complexes, synthesis, structure and reactivity of C{sub x} complexes, synthesis and reactivity of alcohol and ether complexes, new catalysts for the epimerization of secondary alcohols; carbon-hydrogen bond activation in alkoxide complexes, pi/sigma equilibria in metal/O=CXX' complexes, and other hydrocarbon ligands; miscellaneous.(WET)

  19. Large Area Nanolithographic Templates by Selective Etching of Chemically Stained Block Copolymer Thin Films

    NASA Astrophysics Data System (ADS)

    Olayo-Valles, Roberto; Lund, Michael S.; Leighton, C.; Hillmyer, Marc A.

    2004-03-01

    Block copolymer thin films have been employed as effective template precursors for the preparation of inorganic nanostructure arrays. We have prepared nanoscopic templates from polystyrene-polylactide (PS-PLA) diblock copolymer thin films where the minor PLA component forms cylinders in a matrix of PS. Controlled thickness, large area PS-PLA films were spin coated on a variety of substrates (MgO, Al_2O_3, GaAs, Al, Cu, SiO_2). In all cases, annealing the films above the glass transition temperature of both blocks induced spontaneous perpendicular orientation of the cylinders. Selectively staining the PS phase with RuO4 followed by oxygen reactive ion etching produced a corresponding nanoporous template. Metal nanodot arrays were then prepared by deposition of a metal layer on the template followed by liftoff of the polymer mask. The generic nature of this methodology allows for the growth of magnetic nanostructures on single crystal substrates.

  20. 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.

  1. DNA-templated three-branched nanostructures for nanoelectronic devices.

    PubMed

    Becerril, Héctor A; Stoltenberg, Randall M; Wheeler, Dean R; Davis, Robert C; Harb, John N; Woolley, Adam T

    2005-03-09

    Three-branched DNA molecules have been designed and assembled from oligonucleotide components. These nucleic acid constructs contain double- and single-stranded regions that control the hybridization behavior of the assembly. Specific localization of a single streptavidin molecule at the center of the DNA complex has been investigated as a model system for the directed placement of nanostructures. Highly selective silver and copper metallization of the DNA template has also been characterized. Specific hybridization of these DNA complexes to oligonucleotide-coupled nanostructures followed by metallization should provide a bottom-up self-assembly route for the fabrication and characterization of discrete three-terminal nanodevices.

  2. Method of making metal oxide ceramic membranes with small pore sizes

    DOEpatents

    Anderson, Marc A.; Xu, Qunyin

    1992-01-01

    A method for the production of metal oxide ceramic membranes is composed of very small pore size. The process is particularly useful in the creation of titanium and other transition metal oxide membranes. The method utilizes a sol-gel process in which the rate of particle formation is controlled by substituting a relatively large alcohol in the metal alkoxide and by limiting the available water. Stable, transparent metal oxide ceramic membranes are created having a narrow distribution of pore size, with the pore diameter being manipulable in the range of 5 to 40 Angstroms.

  3. 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.

  4. Template boundary definition in mammalian telomerase.

    PubMed

    Chen, Jiunn-Liang; Greider, Carol W

    2003-11-15

    Telomerase uses a short template sequence in its intrinsic RNA component to synthesize telomere repeats. Disruption of the helix P1b in human telomerase RNA or alteration of its distance from the template resulted in telomerase copying residues past the normal template boundary both in vivo and in vitro. Therefore, helix P1b is important for template boundary definition in human telomerase. Mouse telomerase RNA lacks helix P1b, and the boundary is established at 2 nt downstream of the 5'-end. The divergent structure of boundary definition elements in mammals, yeast, and ciliates suggests diverse mechanisms for template boundary definition in telomerase.

  5. DNA-templated nanowires: morphology and electrical conductivity

    NASA Astrophysics Data System (ADS)

    Watson, Scott M. D.; Pike, Andrew R.; Pate, Jonathan; Houlton, Andrew; Horrocks, Benjamin R.

    2014-03-01

    DNA-templating has been used to create nanowires from metals, compound semiconductors and conductive polymers. The mechanism of growth involves nucleation at binding sites on the DNA followed by growth of spherical particles and then, under favourable conditions, a slow transformation to a smooth nanowire. The final transformation is favoured by restricting the amount of templated material per unit length of template and occurs most readily for materials of low surface tension. Electrical measurements on DNA-templated nanowires can be facilitated using three techniques: (i) standard current-voltage measurements with contact electrodes embedded in a dielectric so that there is a minimal step height at the dielectric/electrode boundary across which nanowires may be aligned by molecular combing, (ii) the use of a dried droplet technique and conductive AFM to determine contact resistance by moving the tip along the length of an individual nanowire and (iii) non-contact assessment of conductivity by scanned conductance microscopy on Si/SiO2 substrates.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. LTL - The Little Template Library

    NASA Astrophysics Data System (ADS)

    Gössl, C. A.; Drory, N.; Snigula, J.

    2004-07-01

    The Little Template Library is an expression templates based C++ library for array processing, image processing, FITS and ASCII I/O, and linear algebra. It is released under the GNU Public License (GPL). Although the library is developed with application to astronomical image and data processing in mind, it is by no means restricted to these fields of application. In fact, it qualifies as a fully general array processing package. Focus is laid on a high abstraction level regarding the handling of expressions involving arrays or parts thereof and linear algebra related operations without the usually involved negative impact on performance. The price to pay is dependence on a compiler implementing enough of the current ANSI C++ specification, as well as significantly higher demand on resources at compile time. The LTL provides dynamic arrays of up to 5 dimensions, sub-arrays and slicing, support for fixed size vectors and matrices including basic linear algebra operations, expression templates based evaluation, and I/O facilities for columnar ASCII and FITS format files. In addition it supplies utility classes for statistics, linear and non-linear least squares fitting, and command line and configuration file parsing. YODA (Drory 2002) and all elements of the WeCAPP reduction pipeline (Riffeser et al. 2001, Gössl & Riffeser 2002, 2003) were implemented using the LTL.

  11. 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.

  12. 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.

  13. Functional Programming with C++ Template Metaprograms

    NASA Astrophysics Data System (ADS)

    Porkoláb, Zoltán

    Template metaprogramming is an emerging new direction of generative programming. With the clever definitions of templates we can force the C++ compiler to execute algorithms at compilation time. Among the application areas of template metaprograms are the expression templates, static interface checking, code optimization with adaption, language embedding and active libraries. However, as template metaprogramming was not an original design goal, the C++ language is not capable of elegant expression of metaprograms. The complicated syntax leads to the creation of code that is hard to write, understand and maintain. Although template metaprogramming has a strong relationship with functional programming, this is not reflected in the language syntax and existing libraries. In this paper we give a short and incomplete introduction to C++ templates and the basics of template metaprogramming. We will enlight the role of template metaprograms, and some important and widely used idioms. We give an overview of the possible application areas as well as debugging and profiling techniques. We suggest a pure functional style programming interface for C++ template metaprograms in the form of embedded Haskell code which is transformed to standard compliant C++ source.

  14. 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.

  15. 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.

  16. DNA-templated gold nanowires

    NASA Astrophysics Data System (ADS)

    Mohammadzadegan, Reza; Mohabatkar, Hassan; Sheikhi, Mohammad Hossein; Safavi, Afsaneh; Khajouee, Mahmood Barati

    2008-10-01

    We have developed simple methods of reproducibly creating deoxyribonucleic acid (DNA)-templated gold nanowires on silicon. First DNA nanowires were aligned on silicon surfaces. Briefly, modified silicon wafer was soaked in the DNA solution, and then the solution was removed using micropipettes; the surface tension at the moving air-solution interface is sufficient to align the DNA nanowires on the silicon wafer. In another attempt, an aqueous dispersion of sodium azide-stabilized gold nanoparticles was prepared. The nanoparticles aligned double-stranded λ-DNA to form a linear nanoparticle array. Continuous gold nanowires were obtained. The above nanowires were structurally characterized using scanning electron microscopy. The results of the characterizations show the wires to be 57-323 nm wide, to be continuous with a length of 2.8-9.5 μm. The use of DNA as a template for the self-assembly of conducting nanowires represents a potentially important approach in the fabrication of nanoscale interconnects.

  17. 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.

  18. 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.

  19. A hybrid approach for face template protection

    NASA Astrophysics Data System (ADS)

    Feng, Y. C.; Yuen, Pong C.; Jain, Anil K.

    2008-03-01

    Biometric template protection is one of the important issues in deploying a practical biometric system. To tackle this problem, many algorithms have been reported in recent years, most of them being applicable to fingerprint biometric. Since the content and representation of fingerprint template is different from templates of other modalities such as face, the fingerprint template protection algorithms cannot be directly applied to face template. Moreover, we believe that no single template protection method is capable of satisfying the diversity, revocability, security and performance requirements. We propose a three-step cancelable framework which is a hybrid approach for face template protection. This hybrid algorithm is based on the random projection, class distribution preserving transform and hash function. Two publicly available face databases, namely FERET and CMU-PIE, are used for evaluating the template protection scheme. Experimental results show that the proposed method maintains good template discriminability, resulting in good recognition performance. A comparison with the recently developed random multispace quantization (RMQ) biohashing algorithm shows that our method outperforms the RMQ algorithm.

  20. Nanoporous carbon supported metal particles: their synthesis and characterisation

    NASA Astrophysics Data System (ADS)

    Yang, Yunxia; Tang, Liangguang; Burke, Nick; Chiang, Ken

    2012-08-01

    In the current work, a simplified hard templating approach is used to synthesise metal (Ag, Rh, Ir and Pt) containing structured carbon. The target metals are first introduced into the NaY zeolite template by wetness impregnation. The metals are carried in the super cages of the zeolite and subsequently embedded in the final structures after the steps of carbonisation and the template removal. Scanning electron microscopy images have confirmed that the carbon structures produced by this method retain the morphology of the original template. Transmission electron microscopy reveals the presence of dispersed metal particles in all the carbon structures produced. The metal loadings in these templated structures can reach 35 wt% without significant losses of surface areas and pore volumes. Selected carbon supported metals are tested for their catalytic activity for the methanation of carbon monoxide. The finding suggested that this method is effective in preparing metal nanoparticles for use as catalysts.

  1. Ferroelectric nanotubes fabricated using nanowires as positive templates

    SciTech Connect

    Alexe, M.; Hesse, D.; Schmidt, V.; Senz, S.; Fan, H. J.; Zacharias, M.; Goesele, U.

    2006-10-23

    The authors report on fabrication and electrical characterization of ferroelectric nanotubes and metal-ferroelectric-metal composite nanotubes using silicon and ZnO nanowires as positive templates. Nanotubes of high aspect ratio with a minimum inner diameter of about 100 nm and a length ranging from 0.5 {mu}m to a few microns have been obtained by magnetron sputtering and/or pulsed laser deposition. Metal-ferroelectric one-dimensional structures were characterized by piezoelectric scanning probe microscopy, showing piezoelectric hysteresis loops and ferroelectric switching. The presented fabrication approach can be used to fabricate three-dimensional capacitors for ferroelectric nonvolatile memories as well as nanosize piezoelectric scanners and actuators.

  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. Ordered macroporous materials by emulsion templating

    NASA Astrophysics Data System (ADS)

    Imhof, A.; Pine, D. J.

    1997-10-01

    Ordered macroporous materials with pore diameters comparable to optical wavelengths are predicted to have unique and highly useful optical properties such as photonic bandgaps and optical stop-bands. Tight control over the pore size distribution might also lead to improved macroporous materials (those with pores greater than approximately 50nm) for application as catalytic surfaces and supports, adsorbents, chromatographic materials, filters, light-weight structural materials, and thermal, acoustic and electrical insulators. Although methods exist for producing ordered porous materials with pore diameters less than 10nm (refs 10, 11), there is no general method for producing such materials with uniform pore sizes at larger length scales. Here we report a new method for producing highly monodisperse macroporous materials with pore sizes ranging from 50nm to several micrometres. Starting with an emulsion of equally sized droplets (produced through a repeated fractionation procedure), we form macroporous materials of titania, silica and zirconia by using the emulsion droplets as templates around which material is deposited through a sol-gel process. Subsequent drying and heat treatment yields solid materials with spherical pores left behind by the emulsion droplets. These pores are highly ordered, reflecting the self-assembly of the original monodisperse emulsion droplets into a nearly crystalline array. We show that the pore size can be accurately controlled, and that the technique should be applicable to a wide variety of metal oxides and even organic polymer gels.

  4. 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.

  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. Anisotropic Electroless Deposition on DNA Origami Templates To Form Small Diameter Conductive Nanowires.

    PubMed

    Uprety, Bibek; Westover, Tyler; Stoddard, Michael; Brinkerhoff, Kamron; Jensen, John; Davis, Robert C; Woolley, Adam T; Harb, John N

    2017-01-24

    An improved method for the metallization of DNA origami is examined in this work. DNA origami, a simple and robust method for creating a wide variety of nanostructured shapes and patterns, provides an enabling template for bottom-up fabrication of next-generation nanodevices. Selective metallization of these DNA templates is needed to make nanoelectronic devices. Here, we demonstrate a metallization process that uses gold nanorod seeds followed by anisotropic plating to provide improved morphology and greater control of the final metallized width of the structure. In our approach, gold nanorods are attached to an origami template to create a seed layer. Electroless gold deposition is then used to fill the gaps between seeds in order to create continuous, conductive nanowires. Importantly, growth during electroless deposition occurs preferentially in the length direction at a rate that is approximately 4 times the growth rate in the width direction, which enables fabrication of narrow, continuous wires. The electrical properties of 49 nanowires with widths ranging from 13 to 29 nm were characterized, and resistivity values as low as 8.9 × 10(-7) Ω·m were measured. The anisotropic metallization process presented here represents important progress toward the creation of nanoelectronic devices by molecularly directed placement of functional components onto self-assembled biological templates.

  7. 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

    2016-09-07

    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.

  8. Air Sampling System Evaluation Template

    SciTech Connect

    Blunt, Brent

    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 of 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.

  9. Zinc finger proteins as templates for metal ion exchange: Substitution effects on the C-finger of HIV nucleocapsid NCp7 using M(chelate) species (M=Pt, Pd, Au).

    PubMed

    de Paula, Queite A; Mangrum, John B; Farrell, Nicholas P

    2009-10-01

    The interactions of monofunctional [MCl(chelate)] compounds (M=Pt(II), Pd(II) or Au(III) and chelate=diethylenetriamine, dien or 2,2',2''-terpyridine, terpy) with the C-terminal finger of the HIV nucleocapsid NCp7 zinc finger (ZF) were studied by mass spectrometry and circular dichroism spectroscopy. In the case of [M(dien)] species, Pt(II) and Pd(II) behaved in a similar fashion with evidence of adducts caused by displacement of Pt-Cl or Pd-Cl by zinc-bound thiolate. Labilization, presumably under the influence of the strong trans influence of thiolate, resulted in loss of ligand (dien) as well as zinc ejection and formation of species with only Pd(II) or Pt(II) bound to the finger. For both Au(III) compounds the reactions were very fast and only "gold fingers" with no ancillary ligands were observed. For all terpyridine compounds ligand scrambling and metal exchange occurred with formation of [Zn(terpy)](2+). The results conform well to those proposed from the study of model Zn compounds such as N,N'-bis(2-mercapto-ethyl)-1,4-diazacycloheptanezinc(II), [Zn(bme-dach)](2). The possible structures of the adducts formed are discussed and, for Pt(II) and Pd(II), the evidence for possible expansion of the zinc coordination sphere from four- to five-coordinate is discussed. This observation reinforces the possibility of change in geometry for zinc in biology, even in common "structural" sites in metalloenzymes. The results further show that the extent and rate of zinc displacement by inorganic compounds can be modulated by the nature (metal, ligands) of the reacting compound.

  10. Template synthesis of ordered macroporous hydroxyapatite bioceramics.

    PubMed

    Ji, Lijun; Jell, Gavin; Dong, Yixiang; Jones, Julian R; Stevens, Molly M

    2011-08-28

    Hydroxyapatite has found wide application in bone tissue engineering. Here we use a macroporous carbon template to generate highly ordered macroporous hydroxyapatite bioceramics composed of close-packed hollow spherical pores with interconnected channels. The template has advantages for the preparation of ordered materials.

  11. 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…

  12. 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.

  13. Facile synthetic route to nanosized ferrites by using mesoporous silica as a hard template

    NASA Astrophysics Data System (ADS)

    Valdés-Solís, T.; Tartaj, P.; Marbán, G.; Fuertes, A. B.

    2007-04-01

    Spinel ferrite nanoparticles (AFe2O4; A = Mn, Ni, Cu, Co) of around 10-20 nm have been successfully synthesized via a simple nanocasting route using metal nitrates as precursors and mesoporous silica gel as a hard template. Spinel nanoparticles were formed under a nitrogen atmosphere by the high-temperature decomposition of a mixture of metal nitrates that fill the silica pores. The decomposition reactions occurred in the confined space provided by the mesopores of the silica template. Under these conditions, the silica walls restricted the growth of the oxide particles formed and so nanosized particles were obtained. The incorporation of different cations into the spinel ferrite enabled us to easily modulate the magnetic properties of the nanomaterials prepared by the template method. Depending on the chemical composition and temperature, we were able to obtain samples that display reversible magnetic behaviour (zero coercivity field) and samples with coercivity values as high as 1.3 T (13 000 Oe).

  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. Self-Templated Formation of Hollow Structures for Electrochemical Energy Applications.

    PubMed

    Yu, Le; Wu, Hao Bin; Lou, Xiong Wen David

    2017-02-21

    in virtue of their exceptional composition-/structure-induced merits. As electrode materials for lithium-ion batteries, hybrid or multishelled metal oxides exhibit high cyclability because of their capability to well accommodate the lithium insertion strain. Also the rate capability is effectively improved by the fast lithium insertion/deinsertion in multishelled or hierarchical hollow structures. These exceptional structural merits also significantly enhance the reaction kinetics and prolong the cycling lifetime of metal-sulfides-based electrodes, which enables the assembly of hybrid supercapacitors with high energy and power densities. On the other hand, multicompositional hollow structures with large exposed surface area and rich open pore channels offer abundant robust active sites and fast charge/mass transport for electrocatalytic reactions. These studies demonstrate that the versatility and superiority of self-templated methods for hollow structured functional materials have greatly promoted their applications for electrochemical energy storage and conversion. With continued research efforts, we are expecting greater and broader impacts brought by the rapidly growing family of hollow structures formed by self-templated methods.

  16. Self-Templated Synthesis of Co- and N-Doped Carbon Microtubes Composed of Hollow Nanospheres and Nanotubes for Efficient Oxygen Reduction Reaction.

    PubMed

    Ahn, Sung Hoon; Manthiram, Arumugam

    2017-03-01

    A facile, self-templated strategy for the synthesis of Co- and N-doped carbon microtubular structures composed of nanoscale hollow spheres and nanotubes is proposed. Cobalt oxalate microtubes serve simultaneously as the solid cobalt precursor for the in situ conversion reaction to metal-organic framework and self-templates for the 1D tubular structure.

  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. Poly(ethylene imine)-based granular sorbents by a new process of templated gel-filling. High capacity and selectivity of copper sorption in acidic and alkaline media

    SciTech Connect

    Chanda, M.; Rempel, G.L.

    1995-08-01

    A new process has been developed for making granular gel-type sorbents from chelating resins using metal ion as template. Named as templated gel-filling, the process uses the chosen metal as templating host ion on high-surface-area silica to build a templated gel layer from a solution of the chelating resin in a suitable solvent in which the resin is soluble but its metal complex is insoluble. After cross-linking the templated gel layer, the silica support is removed by alkali to produce a hollow shell of the templated gel. The shells are then soaked in a concentrated aqueous solution of the same metal ion and suspended in the same resin solution to afford gel-filling. The shells thus filled with metal-templated gel are treated with cross-linking agent, followed by acid to remove the template ion and activate the resin for metal sorption. Poly(ethyleneimine) and its partially ethylated derivative have been used to produce granular gel-type sorbents by this process, with Cu(II) as the template ion. These sorbents are found to offer high capacity and selectivity for copper over nickel, cobalt, and zinc in both acidic and alkaline media. Containing a relatively high fraction of imbibed water, the sorbents exhibit markedly enhanced rate behavior, in both sorption and stripping.

  19. A Finger Vein Identification Method Based on Template Matching

    NASA Astrophysics Data System (ADS)

    Zou, Hui; Zhang, Bing; Tao, Zhigang; Wang, Xiaoping

    2016-01-01

    New methods for extracting vein features from finger vein image and generating templates for matching are proposed. In the algorithm for generating templates, we proposed a parameter-templates quality factor (TQF) - to measure the quality of generated templates. So that we can use fewer finger vein samples to generate templates that meet the quality requirement of identification. The recognition accuracy of using proposed methods of finger vein feature extraction and template generation strategy for identification is 97.14%.

  20. Synthesis of nanostructured/macroscopic low-density copper foams based on metal-coated polymer core–shell particles [Templated synthesis of nanowalled low-density copper foams

    SciTech Connect

    Kim, Sung Ho; Bazin, Nick; Shaw, Jessica I.; Yoo, Jae -Hyuck; Worsley, Marcus A.; Satcher, Jr., Joe H.; Sain, John D.; Kuntz, Joshua D.; Kucheyev, Sergei O.; Baumann, Theodore F.; Hamza, Alex V.

    2016-12-06

    A robust, millimeter-sized low-density Cu foam with ~90% (v/v) porosity, ~30 nm thick walls, and ~1 μm diameter spherical pores is prepared by the slip-casting of metal-coated polymer core–shell particles followed by a thermal removal of the polymer. In this paper, we report our key findings that enable the development of the low-density Cu foams. First, we need to synthesize polystyrene (PS) particles coated with a very thin Cu layer (in the range of tens of nanometers). A simple reduction in the amount of Cu deposited onto the PS was not sufficient to form such a low-density Cu foams due to issues related to foam collapse and densification upon the subsequent polymer removal step. Precise control over the morphology of the Cu coating on the particles is essential for the synthesis of a lower density of foams. Second, improving the dispersion of PS–Cu particles in a suspension used for the casting as well as careful optimization of a baking condition minimize the formation of irregular large voids, leading to Cu foams with a more uniform packing and a better connectivity of neighboring Cu hollow shells. Finally, we analyzed mechanical properties of the Cu foams with a depth-sensing indentation test. The uniform Cu foams show a significant improvement in mechanical properties (~1.5× modulus and ~3× hardness) compared to those of uncontrolled foam samples with a similar foam density but irregular large voids. As a result, higher surface areas and a good electric conductivity of the Cu foams present a great potential to future applications.

  1. Synthesis of nanostructured/macroscopic low-density copper foams based on metal-coated polymer core–shell particles [Templated synthesis of nanowalled low-density copper foams

    DOE PAGES

    Kim, Sung Ho; Bazin, Nick; Shaw, Jessica I.; ...

    2016-12-06

    A robust, millimeter-sized low-density Cu foam with ~90% (v/v) porosity, ~30 nm thick walls, and ~1 μm diameter spherical pores is prepared by the slip-casting of metal-coated polymer core–shell particles followed by a thermal removal of the polymer. In this paper, we report our key findings that enable the development of the low-density Cu foams. First, we need to synthesize polystyrene (PS) particles coated with a very thin Cu layer (in the range of tens of nanometers). A simple reduction in the amount of Cu deposited onto the PS was not sufficient to form such a low-density Cu foams duemore » to issues related to foam collapse and densification upon the subsequent polymer removal step. Precise control over the morphology of the Cu coating on the particles is essential for the synthesis of a lower density of foams. Second, improving the dispersion of PS–Cu particles in a suspension used for the casting as well as careful optimization of a baking condition minimize the formation of irregular large voids, leading to Cu foams with a more uniform packing and a better connectivity of neighboring Cu hollow shells. Finally, we analyzed mechanical properties of the Cu foams with a depth-sensing indentation test. The uniform Cu foams show a significant improvement in mechanical properties (~1.5× modulus and ~3× hardness) compared to those of uncontrolled foam samples with a similar foam density but irregular large voids. As a result, higher surface areas and a good electric conductivity of the Cu foams present a great potential to future applications.« less

  2. 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

    2016-10-04

    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.

  3. [Covalent immobilization of urease on polysiloxane templates containing 3-aminopropyl and 3-mercaptopropyl groups].

    PubMed

    Pogorilyĭ, R P; Goncharik, V P; Kozhara, L I; Zub, Iu L

    2008-01-01

    A technique of covalent immobilization of urease on polysiloxane templates, involving the sol-gel method, based on the use of crosslinking reagents (such as glutaraldehyde and Ellman's reagent) has been proposed. Urease, covalently grafted onto the surface of a poly(3-mercaptopropyl)siloxane template, was shown to retain its activity (67-84%) and stability (a decrease of 10% was observed over a period of 300 days). Urease adsorbed onto the poly(3-mercaptopropyl)siloxane template exhibited a higher activity than the native enzyme. The 3-mercaptopropyl groups of the polysiloxane template could be brought into the vicinity of the active metal center of the adsorbed urease and start acting as proton donors, thereby increasing the rate of the reaction catalyzed by the enzyme. Covalent immobilization of urease onto a 3-aminopropyl-containing polysiloxane template was shown to be less efficient, because it resulted in considerable losses of the activity of the enzyme. Conversely, urease adsorbed onto this template exhibited a high activity (60-86%).

  4. 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.

  5. Dislocations limited electronic transport in hydride vapour phase epitaxy grown GaN templates: A word of caution for the epitaxial growers

    SciTech Connect

    Chatterjee, Abhishek Khamari, Shailesh K.; Kumar, R.; Dixit, V. K.; Oak, S. M.; Sharma, T. K.

    2015-01-12

    GaN templates grown by hydride vapour phase epitaxy (HVPE) and metal organic vapour phase epitaxy (MOVPE) techniques are compared through electronic transport measurements. Carrier concentration measured by Hall technique is about two orders larger than the values estimated by capacitance voltage method for HVPE templates. It is learnt that there exists a critical thickness of HVPE templates below which the transport properties of epitaxial layers grown on top of them are going to be severely limited by the density of charged dislocations lying at layer-substrate interface. On the contrary MOVPE grown templates are found to be free from such limitations.

  6. Tunable hierarchical macro/mesoporous gold microwires fabricated by dual-templating and dealloying processes.

    PubMed

    Sattayasamitsathit, Sirilak; Gu, Yonge; Kaufmann, Kevin; Minteer, Shelley; Polsky, Ronen; Wang, Joseph

    2013-09-07

    Tailor-made highly ordered macro/mesoporous hierarchical metal architectures have been created by combining sphere lithography, membrane template electrodeposition and alloy-etching processes. The new double-template preparation route involves the electrodeposition of Au/Ag alloy within the interstitial (void) spaces of polystyrene (PS) microspheres which are closely packed within the micropores of a polycarbonate membrane (PC), followed by dealloying of the Ag component and dissolution of the microsphere and membrane templates. The net results of combining such sphere lithography and silver etching is the creation of highly regular three-dimensional macro/mesoporous gold architecture with well-controlled sizes and shapes. The morphology and porosity of the new hierarchical porous structures can be tailored by controlling the preparation conditions, such as the composition of the metal mixture plating solution, the size of the microspheres template, or the dealloying time. Such tunable macro/mesoporous hierarchical structures offer control of the electrochemical reactivity and of the fuel mass transport, as illustrated for the enhanced oxygen reduction reaction (ORR) and hydrogen-peroxide detection. The new double templated electrodeposition method provides an attractive route for preparing highly controllable multiscale porous materials and diverse morphologies based on different materials and hence holds considerable promise for designing electrocatalytic or bioelectrocatalytic surfaces for a variety sensing and energy applications.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. Template boundary definition in Tetrahymena telomerase.

    PubMed

    Lai, Cary K; Miller, Michael C; Collins, Kathleen

    2002-02-15

    Telomerase elongates chromosome ends by addition of telomeric DNA repeats. The telomerase ribonucleoprotein can copy only a short template sequence within the telomerase RNA subunit. Here, we identify a region of telomerase RNA that is necessary for both correct 5' template boundary definition and high affinity telomerase reverse transcriptase (TERT) interaction. We also demonstrate that TERT mutants in the RNA binding domain compromise both 5' boundary definition and RNA binding. Our results indicate that sequence-specific interaction of a telomerase RNA element with the TERT RNA binding domain, not the active site motifs, defines the template boundary.

  12. Templating irreversible covalent macrocyclization by using anions.

    PubMed

    Kataev, Evgeny A; Kolesnikov, Grigory V; Arnold, Rene; Lavrov, Herman V; Khrustalev, Victor N

    2013-03-11

    Inorganic anions were used as templates in the reaction between a diamine and an activated diacid to form macrocyclic amides. The reaction conditions were found to perform the macrocyclization sufficiently slow to observe a template effect. A number of analytical methods were used to clarify the reaction mechanisms and to show that the structure of the intermediate plays a decisive role in determining the product distribution. For the macrocyclization under kinetic control, it was shown that the amount of a template, the conformational rigidity of building blocks, and the anion affinities of reaction components and intermediates are important parameters that one should take into consideration to achieve high yields.

  13. 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.

  14. Lanthanide Template Synthesis of Trefoil Knots of Single Handedness.

    PubMed

    Zhang, Gen; Gil-Ramírez, Guzmán; Markevicius, Augustinas; Browne, Colm; Vitorica-Yrezabal, Iñigo J; Leigh, David A

    2015-08-19

    We report on the assembly of 2,6-pyridinedicarboxamide ligands (1) with point chirality about lanthanide metal ion (Ln(3+)) templates, in which the helical chirality of the resulting entwined 3:1 ligand:metal complexes is covalently captured by ring-closing olefin metathesis to form topologically chiral molecular trefoil knots of single handedness. The ligands do not self-sort (racemic ligands form a near-statistical mixture of homoleptic and heteroleptic lanthanide complexes), but the use of only (R,R)-1 leads solely to a trefoil knot of Λ-handedness, whereas (S,S)-1 forms the Δ-trefoil knot with complete stereoselectivity. The knots and their isomeric unknot macrocycles were characterized by NMR spectroscopy, mass spectrometry, and X-ray crystallography and the expression of the chirality that results from the topology of the knots studied by circular dichroism.

  15. Condensation of activated diguanylates on a poly(C) template.

    PubMed

    Lohrmann, R; Bridson, P K; Orgel, L E

    1981-01-01

    We have studied the metal-ion catalysis of a number of reactions of the isomers of ImpGpG on a poly(C) template. In the absence of a catalytic metal ion, oligomers at least up to (pG)20 are obtained from the ImpGpG isomers in a 1-methylimidazole buffer. The Pb2+ ion improves the yield of longer oligomers and changes substantially the distribution of linkage isomers. The Pb2+ ion greatly improves the yield of longer oligomers obtained from G and ImpGpG on a poly(C) template. The self-condensation of ImpGpG in a 2, 6-lutidine buffer is much less efficient than in a 1-methylimidazole buffer. The Zn2+ greatly increases the yield of products from the [3'-5']-linked dimer, but fails to catalyze the formation of long oligomers from the [2'-5']-linked dimer. The bonds formed in the Zn2+-catalyzed self-condensation of ImpG3pG on poly(C) are mainly [3'-5']-linked.

  16. Universal soft matter template: from photonic to metamaterial applications

    NASA Astrophysics Data System (ADS)

    Umeton, Cesare; De Sio, Luciano; Caputo, Roberto; Ferjani, Sameh; Strangi, Giuseppe; Bartolino, Roberto

    2011-10-01

    We report on the realization and characterization of a polymeric template sculptured in photosensitive material, on a chemical inert surface. The structure is devoted to micro/nanoconfinement and stabilization of a wide range of organic and nano-particle components with selfarrangement properties at the nanoscale [1]. High quality morphology of a polymeric, micropatterned, array is obtained by combining a, nano-precision level, optical holographic setup and a multi-step chemico-physical process. The "universal" template represents the basic platform to be filled with different organic materials, which can also include metallic nano-particles. The long range self-organization is induced without making use of any kind of surface chemistry. Due to their capability of exhibiting self organization, light responsive Liquid Crystals (LC) [2] and short pitch Cholesterics LC [3] have been exploited, and experimental studies have been carried out in order to investigate the photo-optical and elecro-optical response of obtained composite structures for the realization of photonic devices. Finally, the possibility of including metallic nano-particles has been also investigated, with the aim of inducing a "metamaterial" behavior of the realized structure.

  17. Nanoparticle Array Assembly Using Chemical Templates

    NASA Astrophysics Data System (ADS)

    Adams, Sarah Marie

    This dissertation demonstrates chemically-driven self-assembly techniques to produce assemblies of closely-spaced metal nanoparticles from colloidal nanoparticle solution in order to engineer enhanced optical fields. Planar nanoparticle assemblies provide a platform for a multitude of applications and material architectures. With nanoscale inter-particle spacing, metallic nanoparticles enable increased efficiency of photovoltaic devices due to light focusing and enhancement of electromagnetic fields useful for optical sensing of molecules due to coupling of the plasmon resonance in nanoparticle gaps. For molecular sensors, development of self-assembled two-dimensional assemblies of closely-spaced nanoparticles is useful for producing surface plasmon resonance sensors and surface-enhanced Raman spectroscopy (SERS) based sensing. Using chemical self-assembly, monodisperse, colloidal gold nanoparticles were attached on self-organized polymer templates in order to pattern assemblies of nanoparticle clusters with sub-10 nanometer inter-particle spacing. First citrate-stabilized Au nanoparticles were functionalized with thioctic acid ligands in solution. Then poly(methyl methacrylate) domains in phase-separated poly(styrene-block-methyl methacrylate) (PS-b-PMMA) thin films were chemically modified with surface amine functional groups. Au nanoparticles were preferentially attached to the functionalized PMMA surface domains using cross-linking chemistry. This method allows for versatility of size, shape, and composition. In this dissertation, we demonstrated attachment of 5, 10, and 20 nm Au and 20 nm Ag nanoparticles. PS-b-PMMA thin films also exhibit versatility of domain size and morphology by varying polymer molecular weights. The nanoparticle diameter to PMMA domain size ratio influenced the cluster size. As the ratio decreased, larger clusters were observed on PMMA domains with increased frequency. SERS measurement of nanoparticle assemblies showed uniform signal

  18. Dazomet Fumigant Management Plan Phase 2 Templates

    EPA Pesticide Factsheets

    These templates provide a framework for reporting application block information, buffer zones, emergency response plan, tarp plan, soil conditions, air monitoring, and more for pesticide products containing the active ingredient dazomet, such as Basamid G.

  19. Water Quality Exchange Web Template User Guide

    EPA Pesticide Factsheets

    This is a step by step guide to using the WQX Web Monitoring Data Entry Template for Physical/Chemical data to prepare your data for import into the WQX Web tool, and subsequent transfer to the STORET Data Warehouse.

  20. Using wavelets to learn pattern templates

    NASA Astrophysics Data System (ADS)

    Scott, Clayton D.; Nowak, Robert D.

    2002-07-01

    Despite the success of wavelet decompositions in other areas of statistical signal and image processing, current wavelet-based image models are inadequate for modeling patterns in images, due to the presence of unknown transformations (e.g., translation, rotation, location of lighting source) inherent in most pattern observations. In this paper we introduce a hierarchical wavelet-based framework for modeling patterns in digital images. This framework takes advantage of the efficient image representations afforded by wavelets, while accounting for unknown translation and rotation. Given a trained model, we can use this framework to synthesize pattern observations. If the model parameters are unknown, we can infer them from labeled training data using TEMPLAR (Template Learning from Atomic Representations), a novel template learning algorithm with linear complexity. TEMPLAR employs minimum description length (MDL) complexity regularization to learn a template with a sparse representation in the wavelet domain. We discuss several applications, including template learning, pattern classification, and image registration.

  1. 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…

  2. 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

  3. 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

    2016-02-02

    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.

  4. 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

  5. One-dimensional Si-in-Si(001) template for single-atom wire growth

    NASA Astrophysics Data System (ADS)

    Owen, J. H. G.; Bianco, F.; Köster, S. A.; Mazur, D.; Bowler, D. R.; Renner, Ch.

    2010-08-01

    Single atom metallic wires of arbitrary length are of immense technological and scientific interest. We present atomic-resolution scanning tunneling microscope data of a silicon-only template, which modeling predicts to enable the self-organized growth of isolated micrometer long surface and subsurface single-atom chains. It consists of a one-dimensional, defect-free Si reconstruction four dimers wide—the Haiku core—formed by hydrogenation of self-assembled Bi-nanolines on Si(001) terraces, independent of any step edges. We discuss the potential of this Si-in-Si template as an appealing alternative to vicinal surfaces for nanoscale patterning.

  6. 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

  7. 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.

  8. Pre-operative templating for trauma hemiarthroplasty (Thompson's)

    PubMed Central

    Green, Robert Nicholas; Rushton, Paul R.P.; Kramer, Derek; Inman, Dominic; Partington, Paul F.

    2015-01-01

    Introduction Surgical complications may be avoided by preoperative templating in trauma hemiarthroplasty. Materials and methods Digital templates for the Stryker™ range of Thompson's prostheses were created and fifty trauma patients that had undergone cemented hemiarthroplasty were retrospectively templated by 2 blinded surgeons. Results Templating for prosthesis size was highly accurate with excellent Inter and intra-observer reproducibility. Sensitivity for identifying femoral canals too narrow for a Thompsons was 100%. Conclusions Templating is a valuable tool and should be standard practice in trauma. We have demonstrated that it is possible to generate custom templates to allow accurate templating. PMID:26566327

  9. Assembly of two novel Lindqvist polyoxoanion-templated coordination polymers with standard honeycomb cavities

    NASA Astrophysics Data System (ADS)

    Sha, Jingquan; Huang, Lin; Peng, Jun; Pang, Haijun; Tian, Aixiang; Zhang, Pengpeng; Chen, Yuan; Zhu, Min

    2009-02-01

    Two novel polyoxometalate(POM)-templated coordination polymers: [Cu 2(phnz) 3][M 6O 19] (M = Mo for 1, W for 2; phnz = phenazine), have been hydrothermally synthesized and characterized by routine physical methods and single crystal X-ray diffraction. In the compounds, Lindqvist POMs as templates induce the [Cu 2(phnz) 3] complexes to 2D hexagonal metal-organic framework (MOF), which represents 6 3 topologies of dimensions ca. 13.515 × 13.515 × 13.515 Å. Furthermore, the 2D sheets are held together by Lindqvist POMs into 3D supramolecular networks with 1D channel, and Lindqvist POMs site in the channels. The successful syntheses and isolation of two compounds provide a novel example of the utility of POM clusters as templates for self-assembly extended framework with cavities.

  10. Hyperbranched polymers and dendrimers as templates for organic/inorganic hybrid nanomaterials.

    PubMed

    Huang, Xinhua; Zheng, Sudan; Kim, Il

    2014-02-01

    This paper reviews the recent research and development of hyperbranched polymers (HPs) and dendrimers, and their use as templates for organic-inorganic hybrid nanomaterials. Hyperbranched polymers (HPs) are highly branched macromolecules with three-dimensional globular structures featuring unique properties such as low viscosity, high solubility, and a large number of terminal functional groups compared to their linear analogs. They are easily prepared by (1) condensation polymerization, (2) self-condensing vinyl copolymerization (SCVCP), and (3) ring-opening multibranch polymerization methods. Organic-inorganic hybrid nanomaterials are synthesized by a template approach using HPs/dendrimers. Monometallic, bimetallic (alloy and core/shell), semiconductor, and metal oxide nanoparticles have been prepared by this route. The dendrimer component of these composites serves not only as a template for preparing the nanoparticles but also as a stabilizer for the nanoparticles.

  11. Template based synthesis of gold nanotubes using biologically synthesized gold nanoparticles.

    PubMed

    Ballabh, R; Nara, S

    2015-12-01

    Reliable experimental protocols using green technologies to synthesize metallic nanostructures widen their applications, both biological as well as biomedical. Here, we describe a method for synthesizing gold nanotubes using biologically synthesized gold nanoparticles in a template based approach. E. coli DH5α was used as bionanofactory to synthesize gold nanoparticles. These nanoparticles were then deposited on sodium sulfate (Na2SO4) nanowires which were employed as sacrificial template for gold nanotube (Au-NT) formation. The gold nanoparticles, sodium sulphate nanowires and gold nanotubes were appropriately characterized using transmission electron microscopy. The TEM results showed that the average diameter of gold nanotubes was 72 nm and length up to 4-7 μm. The method discussed herein is better than other reported conventional chemical synthesis approaches as it uses biologically synthesized gold nanoparticles, and does not employ any harsh conditions/solvents for template removal which makes it a clean and ecofriendly method.

  12. Development of semipolar (11-22) LEDs on GaN templates

    NASA Astrophysics Data System (ADS)

    Corbett, B.; Quan, Z.; Dinh, D. V.; Kozlowski, G.; O'Mahony, D.; Akhter, M.; Schulz, S.; Parbrook, P.; Maaskant, P.; Caliebe, M.; Hocker, M.; Thonke, K.; Scholz, F.; Pristovsek, M.; Han, Y.; Humphreys, C. J.; Brunner, F.; Weyers, M.; Meyer, T. M.; Lymperakis, L.

    2016-03-01

    We report on blue and green light-emitting-diodes (LEDs) grown on (11-22)-GaN templates. The templates were created by overgrowth on structured r-plane sapphire substrates. Low defect density, 100 mm diameter GaN templates were obtained by metal organic vapour phase epitaxy (VPE) and hydride VPE techniques. Chemical-mechanical polishing was used to obtain smooth surfaces for the subsequent growth of LED structures. Ohmic contacts to the p-type GaN were obtained despite the lower activated acceptor levels. The LEDs show excellent output power and fast carrier dynamics. Freestanding LEDs have been obtained by use of laser-lift-off. The work is the result of collaboration under the European Union funded ALIGHT project.

  13. 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.

  14. Reactions of aromatic nitro-compounds. LV. Anionic sigma-complexes of sym-trinitrobenzene with the alkoxides of dihydric alcohols

    SciTech Connect

    Mel'nikov, A.I.; Gitis, S.S.; Kaminskii, A.Ya.

    1986-12-20

    The reactions of alkoxides of dihydric alcohols with 2,4,6-trinitroanisole and picryl chloride have been studied. The reaction between 2,4,6-trinitroanisole and sodium 2-hydroxyethoxide, 3-hydroxypropoxide, 4-hydroxybutoxide, and 2-methoxyethoxide gives the unsymmetrical 1-methoxy-1-hydroxyalkoxy-2,4,6-trinitrocyclohexa-2,5-dienate sigma-complexes, which are converted on heating into the 1,1-dihydroxyalkoxy-2,4-6-trinitrocyclohexa-2,5-dienate sigma-complexes. In the case of sodium 1-methoxy-1-(..beta..-hydroxyethoxy)-2,4,6-trinitrocyclohexa-2,5-dienate, heating results in intramolecular spirocyclization of the ..beta..-hydroxyethoxy grouping to give sodium 6,8,10-trinitro-1,4-dioxaspiro(4,5)deca-6,9-dienate. The reaction of sodium 3-hydroxy-propoxide, 4-hydroxybutoxide, 2-methoxyethoxide, and diethyleneglycolate with picryl chloride gives the symmetrical 1,1-dihyroxyalkoxy sigma-complexes, while sodium 2-hydroxyethoxide forms a sigma-complex with a 1,3-dioxolane spiro-ring. The composition and structures of the sigma-complexes, isolated as their sodium salts, were established by their elemental analyses and PMR and IR spectroscopy.

  15. Templated synthesis of magnetic nanowires by electrochemical deposition

    NASA Astrophysics Data System (ADS)

    Tan, Liwen

    There has been much interest in magnetic nanowire because of its perpendicular magnetic anisotropy, enhanced coercivity and large giant magnetoresistance (GMR). So, it is supposed that magnetic nanowires have potential applications to ultra-high-density magnetic recording and high sensitive sensors. Many kinds of methods have been used for the growth of nanowires with diameter ranging from 10nm to few hundred nanometers, however, template assisted electrochemical deposition exhibits many advantages on the growth of metal nanowires. In this work, two-step anodic alumina templates were fabricated for the growth of magnetic nanowires. These templates provided platforms for achieving uniform nanowires. Moreover, nano-imprinting was introduced for the formation of nanopore arrays with long-range order. A new Si3N4 thin film nano-stamp was developed, which is much simpler and more cost-effective. Also, nanopore patterning alignment was successfully achieved without using e-beam lithography. This would provide the opportunity to electrically address each single nanostructure in arrays with high density. The growth of magnetic nanowires was done by eletrodeposition, which included single element Co and Co/Cu multilayered nanowires. Their structures, magnetic and transport properties have been investigated, and were tailored by optimizing the fabrication process. It was shown that the composition of magnetic nanowires was a function of deposition potential. And the structure of electrodeposited Co was affected by the pH of electrolyte and growth rate. GMR and spin transfer torque have been performed on the Co/Cu nanowires. A GMR of 22% was achieved in Co/Cu nanowires. Different magnetoresistance behaviors were observed, which were related to the magnetic anisotropy of the nanowires. It was the first time to detect spin transfer torque in the nanowires with hundreds of Co/Cu bilayers. The switching current density was about 107A/cm2. This process demonstrated the fabrication

  16. 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.

  17. 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.

  18. 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.

  19. Identification on Membrane and Characterization of Phosphoproteins Using an Alkoxide-Bridged Dinuclear Metal Complex as a Phosphate-Binding Tag Molecule

    PubMed Central

    Nakanishi, Tsuyoshi; Ando, Eiji; Furuta, Masaru; Kinoshita, Eiji; Kinoshita-Kikuta, Emiko; Koike, Tohru; Tsunasawa, Susumu; Nishimura, Osamu

    2007-01-01

    We have developed a method for on-membrane direct identification of phosphoproteins, which are detected by a phosphate-binding tag (Phos-tag) that has an affinity to phosphate groups with a chelated Zn2+ ion. This rapid profiling approach for phosphoproteins combines chemical inkjet technology for microdispensing of reagents onto a tiny region of target proteins with mass spectrometry for on-membrane digested peptides. Using this method, we analyzed human epidermoid carcinoma cell lysates of A-431 cells stimulated with epidermal growth factor, and identified six proteins with intense signals upon affinity staining with the phosphate-binding tag. It was already known that these proteins are phosphorylated, and our new approach proved to be effective at rapid profiling of phosphoproteins. Furthermore, we tried to determine their phosphorylation sites by MS/MS analysis after in-gel digestion of the corresponding spots on the 2DE gel to the rapid on-membrane identifications. As one example of use of information gained from the rapid-profiling approach, we successfully characterized a phosphorylation site at Ser-113 on prostaglandin E synthase 3. PMID:18166671

  20. A pyridine alkoxide chelate ligand that promotes both unusually high oxidation states and water-oxidation catalysis

    DOE PAGES

    Michaelos, Thoe K.; Shopov, Dimitar Y.; Sinha, Shashi Bhushan; ...

    2017-03-08

    Here, water-oxidation catalysis is a critical bottleneck in the direct generation of solar fuels by artificial photosynthesis. Catalytic oxidation of difficult substrates such as water requires harsh conditions, so that the ligand must be designed both to stabilize high oxidation states of the metal center and to strenuously resist ligand degradation. Typical ligand choices either lack sufficient electron donor power or fail to stand up to the oxidizing conditions. Our research on Ir-based water-oxidation catalysts (WOCs) has led us to identify a ligand, 2-(2'-pyridyl)-2-propanoate or “pyalk” that fulfills these requirements.

  1. 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

    2010-02-09

    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.

  2. 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.

  3. 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.

  4. A Hybrid Approach to Protect Palmprint Templates

    PubMed Central

    Sun, Dongmei; Xiong, Ke; Qiu, Zhengding

    2014-01-01

    Biometric template protection is indispensable to protect personal privacy in large-scale deployment of biometric systems. Accuracy, changeability, and security are three critical requirements for template protection algorithms. However, existing template protection algorithms cannot satisfy all these requirements well. In this paper, we propose a hybrid approach that combines random projection and fuzzy vault to improve the performances at these three points. Heterogeneous space is designed for combining random projection and fuzzy vault properly in the hybrid scheme. New chaff point generation method is also proposed to enhance the security of the heterogeneous vault. Theoretical analyses of proposed hybrid approach in terms of accuracy, changeability, and security are given in this paper. Palmprint database based experimental results well support the theoretical analyses and demonstrate the effectiveness of proposed hybrid approach. PMID:24982977

  5. 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.

  6. Implementation of the template model of vision.

    PubMed

    Sobey, P J; Horridge, G A

    1990-06-22

    Adopting principles learnt from insect vision we have constructed model of a general-purpose front-end visual system for motion detection that is designed to operate in parallel along each photoreceptor axis with only local connections. The model is also designed to assist electrophysiological analysis of visual processing because it puts the response to a moving scene into sets of template responses similar to the distribution of activity among different neurons. An earlier template model divided the visual image into the fields of adjacent receptors, measured as intensity or receptor modulation at small increments of time. As soon as we used this model with natural scenes, however, we found that we had to look at changes in intensity, not intensity itself. Running the new model also generated new insights into the effects of very fast motion, of blurring the image, and the value of lateral inhibition. We also experimented with ways of measuring the angular velocity of the image moving across the eye. The camera eye is moved at a known speed and the range to objects is calculated from the angular velocity of contrasts moving across the receptor array. The original template model is modified so that contrast is saturated in a new representation of the original image data. This reduces the 8-bit grey-scale image to a log, 3 = 1.6-bit image, which becomes the input to a look-up table of templates. The output consists of groups of responding templates in specific ratios that define the input features, and these ratios lead into types of invariance at a higher level of further logic. At any stage, there can be persistent parallel inputs from all earlier stages. This design would enable groups of templates to be tuned to different expected situations, such as different velocities, different directions and different types of edges.

  7. 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

  8. How useful is templating for total knee replacement component sizing?

    PubMed

    Peek, A C; Bloch, B; Auld, J

    2012-08-01

    This study aims to assess the accuracy of digital templating at our institution, by comparing the templated component sizes with those implanted, and to determine whether templating the preoperative films had any measurable difference on the radiographic outcome, and if, where there was a mismatch between the implanted and templated sizes, the templated size would have been preferable. While a number of studies have evaluated the accuracy of both acetate and digital templating, none has to our knowledge looked back at post-operative radiographs and reviewed these in light of the templated and implanted sizes. Data was collected from 90 PFC Sigma (DePuy, UK) total knee replacements done sequentially, 45 of whom were templated digitally using a calibrating ball and Agfa Orthopaedic Tools software. Postoperative radiographs were graded independently for correct sizing. All templates were within one size of the implanted prosthesis. The femoral component appeared to be more often oversized on the postoperative radiographs in the non-templated group. In addition, most tibial trays that were found be too small had been templated to a larger size. There was a trend towards tibial trays templated too large to have been templated to a smaller size. We conclude that digital templating with a calibrating device is a useful part of preoperative planning for total knee arthroplasty.

  9. 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.

  10. 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.

  11. Vertex finding with deformable templates at LHC

    NASA Astrophysics Data System (ADS)

    Stepanov, Nikita; Khanov, Alexandre

    1997-02-01

    We present a novel vertex finding technique. The task is formulated as a discrete-continuous optimisation problem in a way similar to the deformable templates approach for the track finding. Unlike the track finding problem, "elastic hedgehogs" rather than elastic arms are used as deformable templates. They are initialised by a set of procedures which provide zero level approximation for vertex positions and track parameters at the vertex point. The algorithm was evaluated using the simulated events for the LHC CMS detector and demonstrated good performance.

  12. Crystal structures of a novel NNN pincer ligand and its dinuclear titanium(IV) alkoxide pincer complex

    PubMed Central

    Pedziwiatr, Jakub; Ghiviriga, Ion; Veige, Adam S.

    2017-01-01

    This report describes a synthetic protocols and the crystal structures involving a novel pincer-type H3[NNN] ligand, namely di-μ-bromido-μ-{2-(2,2-di­methylpropanimido­yl)-N-[2-(2,2-di­methyl­propanimido­yl)-4-methyl­phen­yl]-4-methylaniline}-bis­[(diethyl ether)lithium], [Li2Br2(C24H33N3)(C4H10O)2] (1) and a dinuclear metal complex, namely di-μ-bromido-2:3κ4 Br:Br-bis­{2-(2,2-di­methylpropanimido­yl)-N-[2-(2,2-di­methyl­propanimido­yl)-4-methyl­phen­yl]-4-methylaniline}-1κ3 N,N′,N′′;4κ3 N,N′,N′′-tetra-μ-iso­propano­lato-1:2κ4 O:O;3:4κ4 O:O-diiso­propano­lato-1κO,4κO-2,3-dilithium-1,4-dititanium, [Li2Ti2Br2(C24H32N3)2(C3H7O)6] or {[NHNNH]Ti(OiPr)3(LiBr)2}2 (2). Complex 1, which sits on a twofold rotation axis, is a rare example of a pincer-type ligand which bears ketimine side arms. A unique feature of complex 1 is that the ketimine N atoms have an LiBr(Et2O) fragment bonded to them, with the Li atom adopting a distorted tetra­hedral geometry. This particular fragment creates an LiBr bridge between the two ketimine sidearms, which leads to a cage-type appearance of the ligand. Complex 2 consists of the previously described ligand and a TiIV metal atom in an octa­hedral environment, and is located on an inversion center. Complex 2 crystallizes as a dinuclear species with the metal atoms being bridged by an LiBr entity [the Br atoms are disordered and refined in two positions with their site occupation factors refining to 0.674 (12)/0.372 (12)], and the Li cation being bonded to the isopropoxide O atoms (Li having a tetra­hedral coordination as in 1). The organic ligand of compound 2 exhibits disorder in its periphery groups; isopropyl and tert-butyl groups (occupation factors fixed at 0.6/0.4). The novel [NNN]H3 pincer-type ligand was characterized by multinuclear and multidimensional NMR, HRMS and X-ray crystallography. The dinuclear metal complex 2 was characterized by X-ray crystallography. Although each structure

  13. Crystal structures of a novel NNN pincer ligand and its dinuclear titanium(IV) alkoxide pincer complex.

    PubMed

    Pedziwiatr, Jakub; Ghiviriga, Ion; Abboud, Khalil A; Veige, Adam S

    2017-02-01

    This report describes a synthetic protocols and the crystal structures involving a novel pincer-type H3[NNN] ligand, namely di-μ-bromido-μ-{2-(2,2-di-methylpropanimido-yl)-N-[2-(2,2-di-methyl-propanimido-yl)-4-methyl-phen-yl]-4-methylaniline}-bis-[(diethyl ether)lithium], [Li2Br2(C24H33N3)(C4H10O)2] (1) and a dinuclear metal complex, namely di-μ-bromido-2:3κ(4)Br:Br-bis-{2-(2,2-di-methylpropanimido-yl)-N-[2-(2,2-di-methyl-propanimido-yl)-4-methyl-phen-yl]-4-methylaniline}-1κ(3)N,N',N'';4κ(3)N,N',N''-tetra-μ-iso-propano-lato-1:2κ(4)O:O;3:4κ(4)O:O-diiso-propano-lato-1κO,4κO-2,3-dilithium-1,4-dititanium, [Li2Ti2Br2(C24H32N3)2(C3H7O)6] or {[NHNNH]Ti(O (i) Pr)3(LiBr)2}2 (2). Complex 1, which sits on a twofold rotation axis, is a rare example of a pincer-type ligand which bears ketimine side arms. A unique feature of complex 1 is that the ketimine N atoms have an LiBr(Et2O) fragment bonded to them, with the Li atom adopting a distorted tetra-hedral geometry. This particular fragment creates an LiBr bridge between the two ketimine sidearms, which leads to a cage-type appearance of the ligand. Complex 2 consists of the previously described ligand and a Ti(IV) metal atom in an octa-hedral environment, and is located on an inversion center. Complex 2 crystallizes as a dinuclear species with the metal atoms being bridged by an LiBr entity [the Br atoms are disordered and refined in two positions with their site occupation factors refining to 0.674 (12)/0.372 (12)], and the Li cation being bonded to the isopropoxide O atoms (Li having a tetra-hedral coordination as in 1). The organic ligand of compound 2 exhibits disorder in its periphery groups; isopropyl and tert-butyl groups (occupation factors fixed at 0.6/0.4). The novel [NNN]H3 pincer-type ligand was characterized by multinuclear and multidimensional NMR, HRMS and X-ray crystallography. The dinuclear metal complex 2 was characterized by X-ray crystallography. Although each structure exhibits donor N

  14. 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.

  15. 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

  16. Hollow ZIF-8 Nanoworms from Block Copolymer Templates

    NASA Astrophysics Data System (ADS)

    Yu, Haizhou; Qiu, Xiaoyan; Neelakanda, Pradeep; Deng, Lin; Khashab, Niveen M.; Nunes, Suzana P.; Peinemann, Klaus-Viktor

    2015-10-01

    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.

  17. As flat as it gets: ultrasmooth surfaces from template-stripping procedures.

    PubMed

    Vogel, Nicolas; Zieleniecki, Julius; Köper, Ingo

    2012-07-07

    In an experimentally simple replica process, the natural flatness of mica or polished silicon wafers can be transferred to metal films, resulting in metal surfaces with topographic features in Angstrom dimensions over large areas. Two decades after its invention, the template-stripping process continues to appeal to scientists from diverse research backgrounds primarily due to its simplicity, cost-effectiveness and ability to yield high quality substrates and structures. This article introduces the basic construction process for template-stripped substrates, and reports on a variety of extensions of the process, including the generation of materials contrasts and the design of tailored topographies. It also highlights the use of such substrates in a variety of research fields in nanoscience and technology ranging from surface force measurement and high definition imaging to the self-assembly of model membranes and plasmonics.

  18. As flat as it gets: ultrasmooth surfaces from template-stripping procedures

    NASA Astrophysics Data System (ADS)

    Vogel, Nicolas; Zieleniecki, Julius; Köper, Ingo

    2012-06-01

    In an experimentally simple replica process, the natural flatness of mica or polished silicon wafers can be transferred to metal films, resulting in metal surfaces with topographic features in Angstrom dimensions over large areas. Two decades after its invention, the template-stripping process continues to appeal to scientists from diverse research backgrounds primarily due to its simplicity, cost-effectiveness and ability to yield high quality substrates and structures. This article introduces the basic construction process for template-stripped substrates, and reports on a variety of extensions of the process, including the generation of materials contrasts and the design of tailored topographies. It also highlights the use of such substrates in a variety of research fields in nanoscience and technology ranging from surface force measurement and high definition imaging to the self-assembly of model membranes and plasmonics.

  19. Ion channel mimetic membranes and silica nanotubes prepared from porous aluminum oxide templates

    NASA Astrophysics Data System (ADS)

    Mitchell, David Tanner

    Chapter 1 provides background information on the template synthesis of nanomaterials. The template synthesis method is examined with special attention to the use of membranes containing monodisperse cylindrical pores as templates. Several examples of the utility of template-synthesized nanomaterials are given. The production of one type of template membrane, nanopore alumina, is reviewed. Reviews of sol-gel and silane chemistry are also provided. In Chapter 2, a sol-gel template synthesis process is used to produce silica nanotubes within the pores of alumina templates. The nanotubes can be modified using a variety of chemistries, typically via a silanization process. Because the nanotubes are formed in a template, the interior and exterior surface can be modified independently. Modified nanotubes can be used for drug detoxification or as extractants for the removal of metal ions. The nanotube surface can also be biotinylated, which causes binding to avidinated surfaces. Composite microtubes of silica and various polymers are also prepared. Additionally, Au nanowires are shown to assemble with colloidal Au particles using dithiols as linkers. Chapter 3 describes the attachment of proteins onto template-synthesized silica nanotubes. The proteins are covalently linked via an aldehyde silane bridge that binds to pendant primary amino moieties on the protein. Protein-modified nanotubes function as highly specific extractants. Avidin-modified nanotubes extract biotin-coated Au nanoparticles from solution with high extraction efficiency. Immunoprotein-modified nanotubes extract the corresponding antibody from solution with high specificity. Antibody-modified nanotubes extract one enantiomer from a racemic mix. Enzymes, including drug detoxification enzymes, were also attached to the nanotubes and were shown to retain their catalytic activity. Immunoproteins on the outside of nanotubes can be used to direct nanotube binding, creating specific labeling agents. Chapter 4

  20. How Langmuir-Blodgett trilayers act as templates for directed self-assembly of nanoparticles

    NASA Astrophysics Data System (ADS)

    Mukherjee, Smita; Datta, Alokmay; Biswas, Nupur; Giglia, Angelo; Nannarone, Stefano

    2014-04-01

    Atomic force microscopy (AFM) shows that Langmuir-Blodgett (LB) deposition of dissimilar metal stearates (MSt, M = Co, Zn, Cd) on templates of Co-stearate (Co-T) and Cd-stearate (Cd-T) results in self-assembly of MSts into nanocrystalline grains having clear and consistent morphological habits. The grains are better formed and well separated on Cd-T than on Co-T. Fourier transform infrared spectroscopy (FTIR) results show that the headgroup coordination of the overlayer is tuned by the coordination of the Cd-T template and remains unaffected by that of the Co-T template. They also indicate co-existence of a different kind of headgroup structure that is close to the undissociated fatty acid headgroup but differing more in the two types of carbon-oxygen bonds, suggesting an inter-headgroup bonding such as hydrogen bond that may exist on a nanocrystal surface. Results of synchrotron x-ray diffraction at C K-edge, of ZnSt on Cd-T (ZnSt/Cd-T) and Co-T (ZnSt/Co-T), point to a non-closed packed structure for ZnSt/Cd-T and a closed-packed structure for ZnSt/Co-T, with significant superlattice order in the former. The presence of crystalline phases of ZnSt in the nanometer scale, on LB templates, in contrast to the the presence of lamellar phase in bulk ZnSt, is attributed to the the presence of unidentate metal-carboxylate coordination in the former and absence of it in the latter, creating different gradients of dipolar forces at template overlayer interface. Relative strength of this long-range force over short-range intermolecular forces in the templates qualitatively explains better crystallinity and higher ordering in ZnSt/Cd-T compared to ZnSt/Co-T. We propose that the role of dipole moment gradient between template and overlayer in tuning of these metal-organic nanoparticles may be somewhat similar to structural and optical tunability of semiconductor nanocrystals by thermal and self-equilibrium strain.

  1. Templates Aid Removal Of Defects From Castings

    NASA Technical Reports Server (NTRS)

    Hendrickson, Robert G.

    1992-01-01

    Templates used to correlate defects in castings with local wall thicknesses. Placed on part to be inspected after coated with penetrant dye. Positions of colored spots (indicative of defects) noted. Ultrasonic inspector measures thickness of wall at unacceptable defects only - overall inspection not necessary.

  2. Public Notification - RTCR Treatment Technique Violation Template

    EPA Pesticide Factsheets

    When a PWS receives a Treatment Technique Violation following an RTCR Level 1 or Level 2 assessment, it must issue a public notice to inform consumers of that violation. This template can be used as a guide to prepare that public notice.

  3. 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.

  4. Performance Templates and the Regulation of Learning

    ERIC Educational Resources Information Center

    Lyons, Paul

    2009-01-01

    Purpose: The purpose of this paper is to provide a detailed, theoretical underpinning for the training and performance improvement method: performance template (P-T). The efficacy of P-T, with limitations, has been demonstrated in this journal and in others. However, the theoretical bases of the P-T approach had not been well-developed. The other…

  5. 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.

  6. ARA testbed template based UHE neutrino search

    NASA Astrophysics Data System (ADS)

    Prohira, Steven

    2014-03-01

    The Askaryan Radio Array (ARA) is an in-ice Antarctic neutrino detector deployed near the South Pole. ARA is designed to detect ultra high energy (UHE) neutrinos in the range of 0.1-10 EeV. Data from the ARA testbed, deployed in the 2010-2011 season, is used for a template based neutrino search. Askaryan Radio Array.

  7. Tin(II) amide/alkoxide coordination compounds for production of Sn-based nanowires for lithium ion battery anode materials.

    PubMed

    Boyle, Timothy J; Doan, Thu Q; Steele, Leigh Anna M; Apblett, Christopher; Hoppe, Sarah M; Hawthorne, Krista; Kalinich, Robin M; Sigmund, Wolfgang M

    2012-08-21

    A series of tin(II) amide alkoxides ([(OR)Sn(NMe(2))](n)) and tin(II) alkoxides ([Sn(OR)(2)](n)) were investigated as precursors for the production of tin oxide (SnO(x)) nanowires. The precursors were synthesized from the metathesis of tin dimethylamide ([Sn(NMe(2))(2)](2)) and a series of aryl alcohols {H-OAr = H-OC(6)H(4)(R)-2: R = CH(3) (H-oMP), CH(CH(3))(2) (H-oPP), C(CH(3))(3) (H-oBP)] or [H-OC(6)H(3)(R)(2)-2,6: R = CH(3) (H-DMP), CH(CH(3))(2) (H-DIP), C(CH(3))(3) (H-DBP)]}. The 1:1 products were all identified as the dinuclear species [(OAr)Sn(μ-NMe(2))](2) where OAr = oMP (1), oPP (2), oBP (3), DMP (4), DIP (5), DBP (6). The 1:2 products were identified as either a polymer ([Sn(μ-OAr)(2)](∞) (where OAr = oMP (7), oPP (8)), dinuclear [(OAr)Sn(μ-OAr)](2) (where OAr = oBP (9), DMP (10) or DIP/HNMe(2) (11)), or mononuclear [Sn(DBP)(2)] (12) complexes. These novel families of compounds (heteroleptic 1-6, and homoleptic 7-12) were evaluated for the production of SnO(x) nanowires using solution precipitation (SPPT; oleylamine/octadecene solvent system) or electrospinning (ES; THF solvent) processing conditions. The SPPT route that employed the heteroleptic precursors yielded mixed phases of Sn(o):romarchite [1 (100:0); 2 (80:20); 3 (68:32); 4 (86:14); 5 (66:35); 6 (88:12)], with a variety of spherical sized particles [1 (350-900 nm); 2 (150-1200 nm); 3 (250-950 nm); 4 (20-180 nm); 5 (80-400 nm); 6 (40-200 nm)]. For the homoleptic precursors, similar phased [7 (80:20); 8 (23:77); 9 (15:85); 10 (34:66); 11 (77:23); 12 (77:23)] spherical nanodots were isolated [7 (50-300 nm); 8: (irregular); 10 (200-800 nm); 11 (50-150 nm); 12 (50-450 nm)], except for 9 which formed polycrystalline rods [Sn(o):romarchite (15:85)] with aspect ratios >100. From ES routes, the heteroleptic species were found to form 'tadpole-shaped' materials whereas the homoleptic species formed electrosprayed nanodots. The one exception noted was for 7, where, without use of a polymer matrix

  8. The facile preparation of weakly coordinating anions: structure and characterisation of silverpolyfluoroalkoxyaluminates AgAl(ORF)4, calculation of the alkoxide ion affinity.

    PubMed

    Krossing, I

    2001-01-19

    Purified LiAlH4 reacts with fluorinated alcohols HORF to give LiAl(ORF)4 (RF=-CH(CF3)2, 2a; -C(CH3)(CF3)2, 2b; -C(CF3)3, 2c) in 77 to 90% yield. The crude lithium aluminates LiAl(ORF)4 react metathetically with AgF to give the silver aluminates AgAl(ORF)4 (RF=-CH(CF3)2, 3a; -C(CH3)(CF3)2, 3b; -C(CF3)3, 3c) in almost quantitative yield. The solid-state structures of solvated 3a-c showed that the silver cation is only weakly coordinated (CN(Ag)=6-10; CN = coordination number) by the solvent and/or weak cation - anion contacts Ag-X (X=O, F, Cl, C). The strength of the Ag-X contacts of 3a-c was analysed by Brown's bond-valence method and then compared with other silver salts of weakly coordinating anions (WCAs), for example [CB11H6Cl6]- and [M(OTeF5)n]- (M=B, Sb, n=4, 6). Based on this quantitative picture we showed that the Al[OC(CF3)3]4 anion is one of the most weakly coordinating anions known. Moreover, the AgAl(ORF)4 species are certainly the easiest WCAs to access preparatively (20 g in two days), additionally at low cost. The Al-O bond length of Al(ORF)4- is shortest in the sterically congested Al[OC(CF3)3]4- anion-which is stable in H2O and aqueous HNO3 (35 weight%)--and indicates a strong and highly polar Al-O bond that is resistant towards heterolytic alkoxide ion abstraction. This observation was supported by a series of HF-DFT calculations of OR-, Al(OR)3 and Al(OR)4- at the MPW1PW91 and B3LYP levels (R= CH3, CF3, C(CF3)3). The alkoxide ion affinity (AIA) is highest for R=CF3 (AlA=384 +/- 9 kJ x mol(-1)) and R= C(CF3)3 (AIA=390 +/- 3 kJ x mol(-1)), but lowest for R=CH3 (AIA=363 +/- 7 kJ X mol(-1)). The gaseous AL(ORF)4-anions are stable against the action of the strong Lewis acid ALF3(g) by 88.5 +/- 2.5 (RF=CF3) and 63 +/- 12 kJ X mol(-1) (RF=C(CF3)3), while AL(OCH3)4- decomposes with -91 +/- 2 kJ X mol(-1). Therefore the presented fluorinated aluminates AL(ORF)4- appear to be ideal candidates when large and resistant WCAs are needed, for example, in

  9. Self-assembled plasmonic templates produced by microwave annealing: applications to surface-enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Panagiotopoulos, N. T.; Kalfagiannis, N.; Vasilopoulos, K. C.; Pliatsikas, N.; Kassavetis, S.; Vourlias, G.; Karakassides, M. A.; Patsalas, P.

    2015-05-01

    Perhaps the simplest method for creating metal nanoparticles on a substrate is by driving their self-assembly with the thermal annealing of a thin metal film. By properly tuning the annealing parameters one hopes to discover a recipe that allows the pre-determined design of the NP arrangement. However, thermal treatment is known for detrimental effects and is not really the manufacturer’s route of choice when it comes to large-scale applications. An alternative method is the use of microwave annealing, a method that has never been applied for metal processing, due to the high reflectance of microwave radiation at the surface of a metal. However, in this work we challenge the widely used nanostructuring methods by proving the microwave’s annealing ability to produce plasmonic templates, out of extremely thin metal films, by simply using a domestic microwave oven apparatus. We show that this process is generic and independent of the deposition method used for the metal and we further quantify the suitability of these plasmonic templates for use in surface-enhanced Raman scattering applications.

  10. 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.

  11. Metallization of branched DNA origami for nanoelectronic circuit fabrication.

    PubMed

    Liu, Jianfei; Geng, Yanli; Pound, Elisabeth; Gyawali, Shailendra; Ashton, Jeffrey R; Hickey, John; Woolley, Adam T; Harb, John N

    2011-03-22

    This work examines the metallization of folded DNA, known as DNA origami, as an enabling step toward the use of such DNA as templates for nanoelectronic circuits. DNA origami, a simple and robust method for creating a wide variety of shapes and patterns, makes possible the increased complexity and flexibility needed for both the design and assembly of useful circuit templates. In addition, selective metallization of the DNA template is essential for circuit fabrication. Metallization of DNA origami presents several challenges over and above those associated with the metallization of other DNA templates such as λ-DNA. These challenges include (1) the stability of the origami in the processes used for metallization, (2) the enhanced selectivity required to metallize small origami structures, (3) the increased difficulty of adhering small structures to the surface so that they will not be removed when subject to multiple metallization steps, and (4) the influence of excess staple strands present with the origami. This paper describes our efforts to understand and address these challenges. Specifically, the influence of experimental conditions on template stability and on the selectivity of metal deposition was investigated for small DNA origami templates. These templates were seeded with Ag and then plated with Au via an electroless deposition process. Both staple strand concentration and the concentration of ions in solution were found to have a significant impact. Selective continuous metal deposition was achieved, with an average metallized height as small as 32 nm. The shape of branched origami was also retained after metallization. These results represent important progress toward the realization of DNA-templated nanocircuits.

  12. [Ligand intermediates in metal-catalyzed reactions]. Progress report, July 1, 1989--June 30, 1992

    SciTech Connect

    Not Available

    1992-08-01

    This report consists of sections on sigma bond complexes of alkenes, a new carbon-hydrogen bond activation reaction of alkene complexes, carbon-hydrogen bond migrations in alkylidene complexes, carbon- hydrogen bond migrations in alkyne complexes, synthesis, structure and reactivity of C{sub x} complexes, synthesis and reactivity of alcohol and ether complexes, new catalysts for the epimerization of secondary alcohols; carbon-hydrogen bond activation in alkoxide complexes, pi/sigma equilibria in metal/O=CXX` complexes, and other hydrocarbon ligands; miscellaneous.(WET)

  13. 48 CFR 302.7100 - HHS standard templates and formats.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... GENERAL DEFINITIONS OF WORDS AND TERMS HHS Standard Templates and Formats 302.7100 HHS standard templates..., may be accessed on the ASFR/OGAPA/DA Internet Web site. A complete listing of the standard...

  14. 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.

  15. 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.

  16. 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.

  17. Emergency department documentation templates: variability in template selection and association with physical examination and test ordering in dizziness presentations

    PubMed Central

    2011-01-01

    Background Clinical documentation systems, such as templates, have been associated with process utilization. The T-System emergency department (ED) templates are widely used but lacking are analyses of the templates association with processes. This system is also unique because of the many different template options available, and thus the selection of the template may also be important. We aimed to describe the selection of templates in ED dizziness presentations and to investigate the association between items on templates and process utilization. Methods Dizziness visits were captured from a population-based study of EDs that use documentation templates. Two relevant process outcomes were assessed: head computerized tomography (CT) scan and nystagmus examination. Multivariable logistic regression was used to estimate the probability of each outcome for patients who did or did not receive a relevant-item template. Propensity scores were also used to adjust for selection effects. Results The final cohort was 1,485 visits. Thirty-one different templates were used. Use of a template with a head CT item was associated with an increase in the adjusted probability of head CT utilization from 12.2% (95% CI, 8.9%-16.6%) to 29.3% (95% CI, 26.0%-32.9%). The adjusted probability of documentation of a nystagmus assessment increased from 12.0% (95%CI, 8.8%-16.2%) when a nystagmus-item template was not used to 95.0% (95% CI, 92.8%-96.6%) when a nystagmus-item template was used. The associations remained significant after propensity score adjustments. Conclusions Providers use many different templates in dizziness presentations. Important differences exist in the various templates and the template that is used likely impacts process utilization, even though selection may be arbitrary. The optimal design and selection of templates may offer a feasible and effective opportunity to improve care delivery. PMID:21435250

  18. 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.

  19. 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.

  20. 21 CFR 888.4800 - Template for clinical use.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Template for clinical use. 888.4800 Section 888...) MEDICAL DEVICES ORTHOPEDIC DEVICES Surgical Devices § 888.4800 Template for clinical use. (a) Identification. A template for clinical use is a device that consists of a pattern or guide intended for...

  1. Pore development in carbonized hemoglobin by concurrently generated MgO template for activity enhancement as fuel cell cathode catalyst.

    PubMed

    Maruyama, Jun; Hasegawa, Takahiro; Amano, Taiji; Muramatsu, Yasuji; Gullikson, Eric M; Orikasa, Yuki; Uchimoto, Yoshiharu

    2011-12-01

    Various carbon materials with a characteristic morphology and pore structure have been produced using template methods in which a carbon-template composite is once formed and the characteristic features derived from the template are generated after the template removal. In this study, hemoglobin, which is a natural compound that could be abundantly and inexpensively obtained, was used as the carbon material source to produce a carbonaceous noble-metal-free fuel cell cathode catalyst. Magnesium oxide was used as the template concurrently generated with the hemoglobin carbonization from magnesium acetate mixed with hemoglobin as the starting material mixture to enable pore development for improving the activity of the carbonized hemoglobin for the cathodic oxygen reduction. After removal of the MgO template, the substantially developed pores were generated in the carbonized hemoglobin with an amorphous structure observed by total-electron-yield X-ray absorption. The extended X-ray absorption fine structure at the Fe-K edge indicated that Fe was coordinated with four nitrogen atoms (Fe-N(4) moiety) in the carbonized hemoglobin. The oxygen reduction activity of the carbonized hemoglobin evaluated using rotating disk electrodes was dependent on the pore structure. The highly developed pores led to an improved activity.

  2. 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.

  3. A multi-template combination algorithm for protein comparative modeling

    PubMed Central

    Cheng, Jianlin

    2008-01-01

    Background Multiple protein templates are commonly used in manual protein structure prediction. However, few automated algorithms of selecting and combining multiple templates are available. Results Here we develop an effective multi-template combination algorithm for protein comparative modeling. The algorithm selects templates according to the similarity significance of the alignments between template and target proteins. It combines the whole template-target alignments whose similarity significance score is close to that of the top template-target alignment within a threshold, whereas it only takes alignment fragments from a less similar template-target alignment that align with a sizable uncovered region of the target. We compare the algorithm with the traditional method of using a single top template on the 45 comparative modeling targets (i.e. easy template-based modeling targets) used in the seventh edition of Critical Assessment of Techniques for Protein Structure Prediction (CASP7). The multi-template combination algorithm improves the GDT-TS scores of predicted models by 6.8% on average. The statistical analysis shows that the improvement is significant (p-value < 10-4). Compared with the ideal approach that always uses the best template, the multi-template approach yields only slightly better performance. During the CASP7 experiment, the preliminary implementation of the multi-template combination algorithm (FOLDpro) was ranked second among 67 servers in the category of high-accuracy structure prediction in terms of GDT-TS measure. Conclusion We have developed a novel multi-template algorithm to improve protein comparative modeling. PMID:18366648

  4. Carbon Nanotube Templated Asembly of Protein

    SciTech Connect

    Liu, Guodong; Lin, Yuehe

    2006-04-01

    This paper describes a novel general strategy for fabricating protein-polyion multilayers by electrostatic layer-by-layer (LBL) self-assembly on a carbon nanotube (CNT) template. Such a noncovalent functionalization method is important for preserving the activity of biomolecules and the mechanical and electrical properties of CNTs. Glucose oxidase and poly (diallydimethylammonium) chloride polymer were used as a model to investigate the LBL process on a CNT template. High-resolution transmission electron microscopy and electrochemical characterization confirm the formation of LBL nanostructures on carboxyl functionalized CNTs. We have also demonstrated the applications of these nanoshell bioreactors to the direct electrochemistry of proteins and biosensing. This strategy can be applied to assemble other biological molecules, such as antibodies, antigens, and DNA, for wide bioassay applications.

  5. Macroporous polymer foams by hydrocarbon templating.

    PubMed

    Shastri, V P; Martin, I; Langer, R

    2000-02-29

    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 m(2)/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.

  6. 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

  7. Assessing particle kinematics via template matching algorithms.

    PubMed

    Weber, M; Fink, M; Fortov, V; Lipaev, A; Molotkov, V; Morfill, G; Petrov, O; Pustylnik, M; Thoma, M; Thomas, H; Usachev, A; Raeth, C

    2016-04-18

    Template matching algorithms represent a viable tool to locate particles in optical images. A crucial factor of the performance of these methods is the choice of the similarity measure. Recently, it was shown in [Gao and Helgeson, Opt. Express 22 (2014)] that the correlation coefficient (CC) leads to good results. Here, we introduce the mutual information (MI) as a nonlinear similarity measure and compare the performance of the MI and the CC for different noise scenarios. It turns out that the mutual information leads to superior results in the case of signal dependent noise. We propose a novel approach to estimate the velocity of particles which is applicable in imaging scenarios where the particles appear elongated due to their movement. By designing a bank of anisotropic templates supposed to fit the elongation of the particles we are able to reliably estimate their velocity and direction of motion out of a single image.

  8. Preparation, characterization and scanned conductance microscopy studies of DNA-templated one-dimensional copper nanostructures.

    PubMed

    Watson, Scott M D; Wright, Nicholas G; Horrocks, Benjamin R; Houlton, Andrew

    2010-02-02

    The synthesis of one-dimensional metal nanostructures can be achieved through the use of DNA molecules as templates to control and direct metal deposition. Copper nanostructures have been fabricated using this strategy, through association of Cu(2+) ions to DNA templates and reduced with ascorbic acid. Due to the possibility that the reduction of the Cu(2+) can result in the preferential formation of Cu(2)O over metallic Cu(0), X-ray photoelectron spectroscopy and X-ray diffraction have been carried out to establish the chemical identity of the nanostructures. Conclusive evidence is found that reduction of the Cu(2+) ions does result in the formation of the desired metallic Cu(0) structures. The morphology of the nanostructured Cu(0) material has also been observed by atomic force microscopy, showing the structures to have a "beads-on-a-string" appearance and being 3.0-5.5 nm in height. The electrical properties of the structures have been investigated by scanned conductance microscopy, showing the Cu(0) structures exhibit much larger electrical resistance than expected for a metallic nanowire. This is thought to be a consequence of their "beads-on-a-string" morphology and small lateral dimensions (sub-10 nm); both these factors would be expected to increase the electron scattering rate, and, further, there are likely to be significant tunneling barriers at the Cu(0) particle-particle junctions.

  9. 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].

  10. Template synthesis and characterizations of nickel nanorods

    SciTech Connect

    Ghosh, T.; Satpati, B.

    2012-06-05

    Template assisted Ni nanorods were grown using electro-deposition process and investigated using an Analytical Transmission Electron Microscope. Transmission Electron Microscopy (TEM) images and diffraction patterns reveal the polycrystalline nature of grown Ni nanorods and the composition of these nanorods were verified using energy dispersive X-ray (EDX) spectroscopy. The morphology of the grown nanorods was also characterized using Scanning Electron Microscope (SEM).

  11. 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.

  12. 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

  13. Highly thymine-dependent formation of fluorescent copper nanoparticles templated by ss-DNA

    NASA Astrophysics Data System (ADS)

    Liu, Guiying; Shao, Yong; Peng, Jian; Dai, Wei; Liu, Lingling; Xu, Shujuan; Wu, Fei; Wu, Xiaohua

    2013-08-01

    Double-stranded DNAs (ds-DNAs) have been identified as efficient templates favoring the formation of fluorescent copper nanoparticles (Cu NPs). Herein, we have tried to synthesize fluorescent Cu NPs using single-stranded DNAs (ss-DNAs) as templates and to identify the critical DNA sequences. By comparing the results using homopolymer DNAs, hairpin DNAs, and pristine ss-DNAs as templates, we found that DNA thymine base plays a dominant role in producing red-emissive fluorescent Cu NPs on ss-DNA templates. The thymine-dependent growth of the fluorescent Cu NPs is confirmed by Hg2+ mediated T-T base pair in comparison with the other non-specific metal ions, which could be developed into a practical sensor for turn-on fluorescence detection of Hg2+ with a high selectivity. The mechanism is briefly discussed according the DNA sequence-dependent formation of fluorescent Cu NPs. This work demonstrates the sequence role in producing fluorescent Cu NPs that could serve as promising fluorescent nanoprobes in biosensing and DNA-hosted Cu nanomaterials.

  14. Sensitive surface plasmon resonance enabled by templated periodic arrays of gold nanodonuts

    NASA Astrophysics Data System (ADS)

    Dou, Xuan; Lin, Yuh-Chieh; Choi, Baeck; Wu, Kedi; Jiang, Peng

    2016-05-01

    Here we report a simple and scalable colloidal lithography technology for fabricating periodic arrays of gold nanodonuts for sensitive surface plasmon resonance (SPR) analysis. This new bottom-up approach leverages a unique polymer wetting layer between a self-assembled, non-close-packed monolayer silica colloidal crystal and a silicon substrate to template ordered gold nanodonuts with tunable geometries over wafer-sized areas. The processes involved in this templating nanofabrication approach, including spin coating, oxygen plasma etching, and metal sputtering, are all compatible with standard microfabrication technologies. Specular reflection measurements reveal that the efficient electromagnetic coupling of the incident light with the tunable SPR modes of the templated gold nanodonut arrays enables good spectral tunability. Bulk refractive index sensing experiments show that a high SPR sensitivity of ∼758 nm per refractive index unit, which outperforms many plasmonic nanostructures fabricated by both top-down and bottom-up approaches, can be achieved using the templated gold nanodonut arrays. Numerical finite-difference time-domain simulations have also been performed to complement the optical characterization and the theoretical results match well with the experimental measurements.

  15. 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.

  16. Advances in Nanostructured Materials via Templated Sol-Gel Structure Control and Self-Assembly

    NASA Astrophysics Data System (ADS)

    Rudisill, Stephen G.

    This dissertation describes a body of work focused on understanding and improving morphology control of nanoporous structures via their aqueous chemistry. Synthesis of materials was carried out primarily using the Pechini process with metal nitrates and colloidal crystal templates. CeO2 and CeO 2-derived compounds were used for a substantial portion of the dissertation as they are useful for thermochemical cycling experiments. Templated CeO 2 shows a tenfold improvement over an untemplated material as well as a nanoparticle powder under lab-scale thermochemical cycling experiments. The Pechini process itself was then investigated as a means to obtain greater structural control over colloidal crystal templated materials. The process was demonstrated to involve phase separation, which allowed for the production of microspheres and bicontinuous networks of templated CeO 2-based solids. Microspheres produced were between 1--3 microm in size, with polydispersity less than 15%. Further experimentation demonstrated that this phase separation methodology was generalizable to Fe2O 3 and Mn3O4, though higher polydispersities were obtained for these materials. The final research project accomplished in this dissertation involves a method to produce ordered collagen fibrils through the incorporation of nanocrystalline cellulose during fibrillogenesis. Results were verified via scanning electron microscopy and a mechanism was proposed based on infrared spectroscopy results indicating a decrease in collagen-collagen hydrogen bonding.

  17. 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

  18. 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

  19. Template learning in morphological neural nets

    NASA Astrophysics Data System (ADS)

    Davidson, Jennifer L.; Sun, K.

    1991-07-01

    This paper presents an application of morphology neural networks to a template learning problem. Morphology neural networks are a nonlinear version of the familiar artificial neural networks. Typically, an artificial neural net is used to solve pattern classification problems One useful characterization of many neural network algorithms is the ability to 'learn' to respond correctly to new data based only on a selection of known data responses. For example, in the multilayer perceptron model, the 'learning' is a procedure whereby parameters are fed back from output to input neurons and the weights changed to give a better response. The morphological neural net in this paper solves a different type of image processing problem. Specifically, given an input image and an output image which corresponds to a dilated version of the input, one would like to determine what template produced the output. The problem corresponds to teaching the network to solve for the weights in a morphological net, as the weights are the template's values. A reasonable method has been investigated for the boolean case; in this paper results are presented for gray scale images. Image algebra has been shown to provide a succinct expression of neural networks algorithms and also to allow a generalization of neural networks, and thus the authors describe the algorithm in image algebra. The remainder of the paper gives a brief discussion of image algebra, the relationship of image algebra and neural networks, a recap of the dilation morphology neural network boolean for boolean images, and the generalization to grayscale data.

  20. 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.

  1. 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.

  2. UV NIL template making and imprint evaluation

    NASA Astrophysics Data System (ADS)

    Sasaki, Shiho; Hiraka, Takaaki; Mizuochi, Jun; Fujii, Akiko; Sakai, Yuko; Sutou, Takanori; Yusa, Satoshi; Kuriyama, Koki; Sakaki, Masashi; Morikawa, Yasutaka; Mohri, Hiroshi; Hayashi, Naoya

    2008-10-01

    UV NIL shows excellent resolution capability with remarkable low line edge roughness, and has been attracting pioneers in the industry who were searching for the finest patterns. We have been focused on the resolution improvement in NIL template making with a 100keV acceleration voltage spot beam EB writer process, and have established a template making process to meet the requirements of the pioneers. Usually such templates needed just a small field (several hundred microns square or so). Now, for several semiconductor devices, the UV NIL is considered not only as a patterning solution for R&D purpose but eventually as a potential candidate for production, and instead of a small field, a full chip field mask is required. Although the 100kV EB writers have excellent resolution capability, they are adopting spot beams (SB) to generate the pattern and have a fatally low throughput if we need full chip writing. In this paper, we are focusing on the 50keV variable shaped beam (VSB) EB writers, which are used in current 4X photomask manufacturing. The 50keV VSB writers can generate full chip pattern in a reasonable time, and by choosing the right patterning material and process, we achieved resolution down to 28nm.

  3. UV NIL template making and imprint evaluation

    NASA Astrophysics Data System (ADS)

    Sasaki, Shiho; Hiraka, Takaaki; Mizuochi, Jun; Sakai, Yuko; Yusa, Satoshi; Morikawa, Yasutaka; Mohri, Hiroshi; Hayashi, Naoya

    2009-01-01

    UV NIL shows excellent resolution capability with remarkable low line edge roughness, and has been attracting pioneers in the industry who were searching for the finest patterns. We have been focused on the resolution improvement in NIL template making with a 100keV acceleration voltage spot beam EB writer process, and have established a template making process to meet the requirements of the pioneers. Usually such templates needed just a small field (several hundred microns square or so) Now, for several semiconductor devices, the UV NIL is considered not only as a patterning solution for R&D purpose but eventually as a potential candidate for production, and instead of a small field, a full chip field mask is required. Although the 100kV EB writers have excellent resolution capability, they are adopting spot beams (SB) to generate the pattern and have a fatally low throughput if we need full chip writing. In this paper, we are focusing on the 50keV variable shaped beam (VSB) EB writers, which are used in current 4X photomask manufacturing. The 50keV VSB writers can generate full chip pattern in a reasonable time, and by choosing the right patterning material and process, we achieved resolution down to hp28nm, and initial promising results of hp22nm (partial resolution) for line and spaces, and hp26nm for dense holes were observed..

  4. Converting Basic D3 Charts into Reusable Style Templates.

    PubMed

    Harper, Jonathan; Agrawala, Maneesh

    2017-02-07

    We present a technique for converting a basic D3 chart into a reusable style template. Then, given a new data source we can apply the style template to generate a chart that depicts the new data, but in the style of the template. To construct the style template we first deconstruct the input D3 chart to recover its underlying structure: the data, the marks and the mappings that describe how the marks encode the data. We then rank the perceptual effectiveness of the deconstructed mappings. To apply the resulting style template to a new data source we first obtain importance ranks for each new data field. We then adjust the template mappings to depict the source data by matching the most important data fields to the most perceptually effective mappings. We show how the style templates can be applied to source data in the form of either a data table or another D3 chart. While our implementation focuses on generating templates for basic chart types (e.g. variants of bar charts, line charts, dot plots, scatterplots, etc.), these are the most commonly used chart types today. Users can easily find such basic D3 charts on the Web, turn them into templates, and immediately see how their own data would look in the visual style (e.g. colors, shapes, fonts, etc.) of the templates. We demonstrate the effectiveness of our approach by applying a diverse set of style templates to a variety of source datasets.

  5. 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

    2016-04-07

    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.

  6. 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.

  7. A Neonatal Bimodal MR-CT Head Template

    PubMed Central

    Mohtasebi, Mehrana; Abrishami Moghaddam, Hamid; Grebe, Reinhard; Gity, Masoumeh; Wallois, Fabrice

    2017-01-01

    Neonatal MR templates are appropriate for brain structural analysis and spatial normalization. However, they do not provide the essential accurate details of cranial bones and fontanels-sutures. Distinctly, CT images provide the best contrast for bone definition and fontanels-sutures. In this paper, we present, for the first time, an approach to create a fully registered bimodal MR-CT head template for neonates with a gestational age of 39 to 42 weeks. Such a template is essential for structural and functional brain studies, which require precise geometry of the head including cranial bones and fontanels-sutures. Due to the special characteristics of the problem (which requires inter-subject inter-modality registration), a two-step intensity-based registration method is proposed to globally and locally align CT images with an available MR template. By applying groupwise registration, the new neonatal CT template is then created in full alignment with the MR template to build a bimodal MR-CT template. The mutual information value between the CT and the MR template is 1.17 which shows their perfect correspondence in the bimodal template. Moreover, the average mutual information value between normalized images and the CT template proposed in this study is 1.24±0.07. Comparing this value with the one reported in a previously published approach (0.63±0.07) demonstrates the better generalization properties of the new created template and the superiority of the proposed method for the creation of CT template in the standard space provided by MR neonatal head template. The neonatal bimodal MR-CT head template is freely downloadable from https://www.u-picardie.fr/labo/GRAMFC. PMID:28129340

  8. 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.

  9. High-throughput drawing and testing of metallic glass nanostructures.

    PubMed

    Hasan, Molla; Kumar, Golden

    2017-03-02

    Thermoplastic embossing of metallic glasses promises direct imprinting of metal nanostructures using templates. However, embossing high-aspect-ratio nanostructures faces unworkable flow resistance due to friction and non-wetting conditions at the template interface. Herein, we show that these inherent challenges of embossing can be reversed by thermoplastic drawing using templates. The flow resistance not only remains independent of wetting but also decreases with increasing feature aspect-ratio. Arrays of assembled nanotips, nanowires, and nanotubes with aspect-ratios exceeding 1000 can be produced through controlled elongation and fracture of metallic glass structures. In contrast to embossing, the drawing approach generates two sets of nanostructures upon final fracture; one set remains anchored to the metallic glass substrate while the second set is assembled on the template. This method can be readily adapted for high-throughput fabrication and testing of nanoscale tensile specimens, enabling rapid screening of size-effects in mechanical behavior.

  10. Solvothermal removal of the organic template from L 3 ("sponge") templated silica monoliths

    NASA Astrophysics Data System (ADS)

    Dabbs, Daniel M.; Mulders, Norbert; Aksay, Ilhan A.

    2006-10-01

    We compare the methods of continuous solvent (Soxhlet) and supercritical solvent extractions for the removal of the organic template from nanostructured silica monoliths. Our monoliths are formed by templating the L 3 liquid crystal phase of cetylpyridinium chloride in aqueous solutions with tetramethoxy silane. The monoliths that result from both Soxhlet and supercritical extraction methods are mechanically robust, optically clear, and free of cracks. The Soxhlet method compares favorably with supercritical solvent extraction in that equivalent L 3-templated silica can be synthesized without the use of specialized reactor hardware or higher temperatures and high pressures, while avoiding noxious byproducts. The comparative effectiveness of various solvents in the Soxhlet process is related to the Hildebrand solubility parameter, determined by the effective surface area of the extracted silica.

  11. High-throughput templated multisegment synthesis of gold nanowires and nanorods.

    PubMed

    Burdick, Jared; Alonas, Eric; Huang, Huang-Chiao; Rege, Kaushal; Wang, Joseph

    2009-02-11

    A cost-effective, high-throughput method for generating gold nanowires and/or nanorods based on a multisegment template electrodeposition approach is described. Using this method, multiple nanowires/nanorods can be generated from a single pore of alumina template membranes by alternately depositing segments of desirable (e.g., gold) and non-desirable metals (e.g., silver), followed by dissolution of the template and the non-desirable metal. Critical cost analysis indicates substantial savings in material requirements, processing times, and processing costs compared to the commonly used single-segment method. In addition to solid gold nanowires/nanorods, high yields of porous gold nanowires/nanorods are obtained by depositing alternate segments of gold-silver alloy and silver from the same gold-silver plating solution followed by selective dissolution of the silver from both segments. It is anticipated that this high-throughput method for synthesizing solid and porous gold nanowires and nanorods will accelerate their use in sensing, electronic, and biomedical applications.

  12. 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.

  13. Shape-Controlled Metal-Metal and Metal-Polymer Janus Structures by Thermoplastic Embossing.

    PubMed

    Hasan, Molla; Kahler, Niloofar; Kumar, Golden

    2016-05-04

    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.

  14. 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

  15. 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

  16. 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.

  17. Remote site-selective C–H activation directed by a catalytic bifunctional template

    NASA Astrophysics Data System (ADS)

    Zhang, Zhipeng; Tanaka, Keita; Yu, Jin-Quan

    2017-03-01

    In chemical syntheses, the activation of carbon–hydrogen (C–H) bonds converts them directly into carbon–carbon or carbon–heteroatom bonds without requiring any prior functionalization. C–H activation can thus substantially reduce the number of steps involved in a synthesis. A single specific C–H bond in a substrate can be activated by using a ‘directing’ (usually a functional) group to obtain the desired product selectively. The applicability of such a C–H activation reaction can be severely curtailed by the distance of the C–H bond in question from the directing group, and by the shape of the substrate, but several approaches have been developed to overcome these limitations. In one such approach, an understanding of the distal and geometric relationships between the functional groups and C–H bonds of a substrate has been exploited to achieve meta-selective C–H activation by using a covalently attached, U-shaped template. However, stoichiometric installation of this template has not been feasible in the absence of an appropriate functional group on which to attach it. Here we report the design of a catalytic, bifunctional nitrile template that binds a heterocyclic substrate via a reversible coordination instead of a covalent linkage. The two metal centres coordinated to this template have different roles: one reversibly anchors substrates near the catalyst, and the other cleaves remote C–H bonds. Using this strategy, we demonstrate remote, site-selective C–H olefination of heterocyclic substrates that do not have the necessary functional groups for covalently attaching templates.

  18. 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

  19. 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

  20. 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.

  1. Electrical and structural properties of ZnO synthesized via infiltration of lithographically defined polymer templates

    DOE PAGES

    Chang-Yong Nam; Stein, Aaron; Kisslinger, Kim; ...

    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

  2. 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.

  3. Supercooling of Hydrogen on Template Materials to Deterministically Seed Ignition-Quality Solid Fuel Layers

    SciTech Connect

    Shin, S. J.; Zepeda-Ruiz, L. A.; Lee, J. R. I.; Baxamusa, S. H.

    2016-09-01

    In this study, we explored templating effects of various materials for hydrogen (H2 and D2) solidification by measuring the degree of supercooling required for liquid hydrogen to solidify below each triple point. The results show high supercooling (>100 mK) for most metallic, covalent, and ionic solids, and low supercooling (<100 mK) for van der Waals (vdW) solids. We attribute the low supercooling of vdW solids to the weak interaction of the substrate and hydrogen. Highly ordered pyrolytic graphite showed the lowest supercooling among materials that are solid at room temperature, but did not exhibit a templating effect within a fill-tube and capsule assembly.

  4. Supercooling of Hydrogen on Template Materials to Deterministically Seed Ignition-Quality Solid Fuel Layers

    DOE PAGES

    Shin, S. J.; Zepeda-Ruiz, L. A.; Lee, J. R. I.; ...

    2016-09-01

    In this study, we explored templating effects of various materials for hydrogen (H2 and D2) solidification by measuring the degree of supercooling required for liquid hydrogen to solidify below each triple point. The results show high supercooling (>100 mK) for most metallic, covalent, and ionic solids, and low supercooling (<100 mK) for van der Waals (vdW) solids. We attribute the low supercooling of vdW solids to the weak interaction of the substrate and hydrogen. Highly ordered pyrolytic graphite showed the lowest supercooling among materials that are solid at room temperature, but did not exhibit a templating effect within a fill-tubemore » and capsule assembly.« less

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Spontaneous emission intensity and anisotropy of quantum dot films in proximity to nanoscale photonic-plasmonic templates

    NASA Astrophysics Data System (ADS)

    Indukuri, Chaitanya; Basu, J. K.

    2016-07-01

    We discuss results on spontaneous emission intensity and lifetime anisotropy of cadmium selenide quantum dot monolayer films placed in close proximity to a porous block copolymer based photonic-plasmonic two dimensional array. The porous block copolymer cylinders can be filled with metal nanoparticles and the concentration of these nanoparticles is varied to control both the photoluminescence intensity and lifetime of a layer of quantum dots placed above the template. Significant emission enhancement is achieved even for the quantum dot layer whose core lies about 1 nm above the template surface. Interestingly, polarised decay lifetime analysis indicates considerable emission anisotropy, as well for these quantum dots. Our results thus demonstrates how such hybrid optical materials can be created with controlled optical properties and suggests extension of this method to other novel two dimensional materials in combination with the photonic-plasmonic template.

  10. 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.

  11. 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.

  12. Progress of UV-NIL template making

    NASA Astrophysics Data System (ADS)

    Hiraka, Takaaki; Mizuochi, Jun; Nakanishi, Yuko; Yusa, Satoshi; Sasaki, Shiho; Morikawa, Yasutaka; Mohri, Hiroshi; Hayashi, Naoya

    2009-04-01

    Nano-imprint lithography (NIL) has been counted as one of the lithography candidates for hp32nm node and beyond and has showed excellent resolution capability with remarkable low line edge roughness that is attracting many researchers in the industry who were searching for the finest patterning technology. Therefore, recently we have been focusing on the resolution improvement on the NIL templates with the 100keV acceleration voltage spot beam (SB) EB writer and the 50keV acceleration voltage variable shaped beam (VSB) EB writer. The 100keV SB writers have high resolution capability, but they show fatally low throughput if we need full chip writing. Usually templates for resolution pioneers needed just a small field (several hundred microns square or so), but recently requirements for full chip templates are increasing. For full chip writing, we have also started the resolution improvement with the 50keV VSB writers used in current 4X photomask manufacturing. The 50keV VSB writers could generate full chip pattern in a reasonable time though resolution limits are inferior to that with the 100keV SB writers. In this paper, we will show latest results with both the 100keV SB and the 50keV VSB EB writers. With the 100keV SB EB writer, we have achieved down to hp15nm resolution for line and space pattern, but found that to achieve further improvement, an innovation in pattern generation method or material would be inevitable. With the 50keV VSB EB writer, we have achieved down to hp22nm resolution for line and space pattern. Though NIL has excellent resolution capability, solutions for defect inspection and repair are not clearly shown yet. In this paper, we will show preliminary inspection results with an EB inspection tool. We tested an EB inspection tool by Hermes Microvision, Inc. (HMI), which was originally developed for and are currently used as a wafer inspection tool, and now have been started to seek the application for mask use, using a programmed defect

  13. 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.

  14. Scale estimation of objects using template matching

    NASA Astrophysics Data System (ADS)

    Gaxiola, Leopoldo N.; Diaz-Ramirez, Victor H.; Tapia, Juan J.

    2016-09-01

    Scale estimation of objects is a challenging problem in image processing. This work presents a novel method to detect and estimate the scaling factor of a target in an observed scene corrupted with additive noise and clutter. Given a set of available views of the target the proposed method is able to detect the target and estimate its scaling factor using a template matched filters and a scale pyramidal representation. The performance of the proposed method is evaluated in synthetic and real-life scenes in different pattern recognition applications. The obtained results are characterized in terms of objective metrics.

  15. 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.

  16. 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.

  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. 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.

  19. 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.

  20. Assessing Usage Patterns of Electronic Clinical Documentation Templates

    PubMed Central

    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 campus, 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

  1. 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.

  2. Macrocycle Synthesis by Chloride-Templated Amide Bond Formation.

    PubMed

    Martí-Centelles, Vicente; Burguete, M Isabel; Luis, Santiago V

    2016-03-04

    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.

  3. 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.

  4. 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.

  5. Random template placement and prior information

    NASA Astrophysics Data System (ADS)

    Röver, Christian

    2010-05-01

    In signal detection problems, one is usually faced with the task of searching a parameter space for peaks in the likelihood function which indicate the presence of a signal. Random searches have proven to be very efficient as well as easy to implement, compared e.g. to searches along regular grids in parameter space. Knowledge of the parameterised shape of the signal searched for adds structure to the parameter space, i.e., there are usually regions requiring to be densely searched while in other regions a coarser search is sufficient. On the other hand, prior information identifies the regions in which a search will actually be promising or may likely be in vain. Defining specific figures of merit allows one to combine both template metric and prior distribution and devise optimal sampling schemes over the parameter space. We show an example related to the gravitational wave signal from a binary inspiral event. Here the template metric and prior information are particularly contradictory, since signals from low-mass systems tolerate the least mismatch in parameter space while high-mass systems are far more likely, as they imply a greater signal-to-noise ratio (SNR) and hence are detectable to greater distances. The derived sampling strategy is implemented in a Markov chain Monte Carlo (MCMC) algorithm where it improves convergence.

  6. 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.

  7. Fluorogenic Templated Reaction Cascades for RNA Detection.

    PubMed

    Velema, Willem A; Kool, Eric T

    2017-03-27

    Nucleic acids detection is essential to the study of biological processes and to diagnosis of pathological states. Although PCR is highly effective in vitro, methods that can function without prior sample preparation, thermal cycling, or enzymes are of interest due to their simplicity. Most current non-PCR detection methods rely on linear signal amplification, which hinders the detection of small amounts of genetic material. To address this limitation, we tested a new strategy for attaining higher-order signal amplification, in which a target sequence templates a chemical ligation and the product of this reaction is in turn detected with a second templated reaction. The method is nonenzymatic, isothermal and fluorogenic, allowing the direct detection of nucleic acids in complex matrices. Using this approach, as little as 500 attomoles (10 pM) could be detected with single nucleotide resolution. In a test of selectivity, single nucleotide substitutions and deletions could successfully be detected, including a deletion that is associated with tetracycline resistance in Helicobacter pylori. Compatibility with biological matrices was demonstrated by the direct detection of rRNA in bacterial lysate. Imaging and detection of target sequences on a solid support further illustrates the potential of the new approach for high-throughput analysis.

  8. Fluid discrimination based on rock physics templates

    NASA Astrophysics Data System (ADS)

    Liu, Qian; Yin, Xingyao; Li, Chao

    2015-10-01

    Reservoir fluid discrimination is an indispensable part of seismic exploration. Reliable fluid discrimination helps to decrease the risk of exploration and to increase the success ratio of drilling. There are many kinds of fluid indicators that are used in fluid discriminations, most of which are single indicators. But single indicators do not always work well under complicated reservoir conditions. Therefore, combined fluid indicators are needed to increase accuracies of discriminations. In this paper, we have proposed an alternative strategy for the combination of fluid indicators. An alternative fluid indicator, the rock physics template-based indicator (RPTI) has been derived to combine the advantages of two single indicators. The RPTI is more sensitive to the contents of fluid than traditional indicators. The combination is implemented based on the characteristic of the fluid trend in the rock physics template, which means few subjective factors are involved. We also propose an inversion method to assure the accuracy of the RPTI input data. The RPTI profile is an intuitionistic interpretation of fluid content. Real data tests demonstrate the applicability and validity.

  9. Influence of template fill in graphoepitaxy directed self-assembly

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    Directed self-assembly (DSA) of block copolymers (BCP) is considered a promising patterning approach for the 7-nm node and beyond. Specifically, a graphoepitaxy process using a cylindrical phase BCP may offer an efficient solution for patterning randomly distributed contact holes with subresolution pitches, such as found in via and cut mask levels. In any graphoepitaxy process, the pattern density impacts the template fill (local BCP thickness inside the template) and may cause defects due to 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. 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 prepattern 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 for DSA-aware design and show that fill is a crucial parameter in graphoepitaxy DSA.

  10. 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.

  11. 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.

  12. 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

    2015-02-02

    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.

  13. Multiplex templating process in one-dimensional nanoscale: controllable synthesis, macroscopic assemblies, and applications.

    PubMed

    Liang, Hai-Wei; Liu, Jian-Wei; Qian, Hai-Sheng; Yu, Shu-Hong

    2013-07-16

    nanoscale building blocks. In this Account, we describe on our recent developments in the multiplex templating synthesis of 1D nanostructures, their macroscopic assemblies, and applications. We first introduce ultrathin TeNWs and their advantages as a templating material. Through the multiplex templating process, we can prepare a family of 1D nanostructures that covers a wide range of materials, including noble metals, metal oxides, semiconductors, carbon, polymers, and their binary and multiple hybrids. We emphasize the reactivity of templating materials and the versatility of templating processes in this Account. On the basis of the templated 1D products, we then describe a series of macroscopic assemblies of 1D nanostructures, including free-standing membranes, films, hydrogels, and aerogels. These exhibit enormous potential for attractive applications, such as liquid filtration and separation, continuous-flow catalysis, electrocatalysis, polymer-based nanocomposites, and superadsorbents, and elastomeric conductors. We believe that the great versatility of templating synthesis, a scalable assembling process, and large-scale synthesis can significantly enhance the application reliability of the 1D nanostructures.

  14. Facile fabrication of high-quality Ag/PS coaxial nanocables based on the mixed mode of soft/hard templates.

    PubMed

    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.

  15. Fabrication of nano-imprint templates for dual-Damascene applications using a high resolution variable shape E-beam writer

    NASA Astrophysics Data System (ADS)

    Pritschow, Marcus; Butschke, Joerg; Irmscher, Mathias; Sailer, Holger; Resnick, Douglas; Thompson, Ecron

    2007-10-01

    A 3D template fabrication process has been developed, which enables the generation of high resolution, high aspect pillars on top of lines. These templates will be used to print both vias and metal lines at once for the dual damascene technology. Due to the complexity of state of the art CMOS designs only a variable shape e-beam (VSB) writer combined with chemically amplified resists (CAR) can be considered for the patterning process. We focused our work especially on the generation of high aspect pillars with a diameter below 50nm and the development of suitable overlay strategies for getting a precise alignment between the two template tiers. In this context we investigated the influence of exposure strategies on the overlay result across the entire imprint area of 25mm × 25mm. Finally, we realized templates according to the MII standard with different test designs and confirmed printability of one of them on a MII tool.

  16. 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

  17. 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.

  18. Chiral nematic stained glass: controlling the optical properties of nanocrystalline cellulose-templated materials.

    PubMed

    Kelly, Joel A; Shopsowitz, Kevin E; Ahn, Jun Myun; Hamad, Wadood Y; MacLachlan, Mark J

    2012-12-18

    Chiral nematic mesoporous materials decorated with metal nanoparticles have been prepared using the templated self-assembly of nanocrystalline cellulose (NCC). By adding small quantities of ionic compounds to aqueous dispersions of NCC and tetramethoxysilane (TMOS), the helical pitch of the chiral nematic structure could be manipulated in a manner complementary to the ratio of NCC/TMOS previously demonstrated by our group. We have studied the transformation of these ion-loaded composites into high surface area mesoporous silica and carbon films decorated with metal nanoparticles through calcination and carbonization, respectively. This general and straightforward approach to prepare chiral nematic metal nanoparticle assemblies may be useful in a variety of applications, particularly for their chiral optical properties.

  19. 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.

  20. 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

  1. Hollow Colloidal Rods formed on a Viral Template

    NASA Astrophysics Data System (ADS)

    Landon, Preston B.; Baughman, Ray; Zakhidov, Anvar; Draper, Rockford; Glosser, R.; Synowczynski, Jennifer; Hirsch, Samuel G.

    2002-10-01

    The Tobacco Mosaic Virus (TMV) is a plant virus that infects tobacco, tomato and over a 100 know other plants. TMV is harmless to humans and is present in nearly every commercial tobacco product. Like most viruses TMV is a monodisperse colloidal particle. TMV is an 18 nanometer wide, 300 nanometer long, hollow cylinder with a 4nm wide hole passing through the center of the cylinder along it length. This cigarette shaped virus is extremely efficient at having it's host replicate identical copies of TMV particles. Tomato plants infected with TMV can be identified by the presence of strange colors visible on the tomato surface. These colors arise from thousands of TMV particles self assembling as ridged rods into ordered structures. Recently, there has been an effort to synthetically grow metal, titanium dioxide and uniform colloidal rod shaped particles of various materials. We have coated TMV with a thin layer of gold by a chemical method in aqueous solutions. These and other uniform virus particles have promise as natural templates to create hollow monodisperse colloidal particles. Hollow colloidal particles have potential application as building blocks for photonic band gap materials and for cell specific drug carriers.

  2. The Oxygen Reduction Electrocatalytic Activity of Cobalt and Nitrogen Co-doped Carbon Nanocatalyst Synthesized by a Flat Template

    NASA Astrophysics Data System (ADS)

    Guo, Chaozhong; Wu, Youcheng; Li, Zhongbin; Liao, Wenli; Sun, Lingtao; Wang, Chao; Wen, Bixia; Li, Yanrong; Chen, Changguo

    2017-02-01

    The design of noble-metal-free catalysts for oxygen reduction reaction (ORR) is very important to the commercialization of fuel cells. Here, we use a Co-modified montmorillonite (Co-MMT) as a flat template to prepare Co- and N-doped nanocarbon ORR catalysts derived from carbonization of polyaniline at controlled temperatures. The use of flat template can hinder the agglomeration of polyaniline during pyrolysis process and optimize the N-rich active site density on the surface. The addition of transition metal Co in the flat MMT template can largely promote the formation of Co-N sites in prepared catalyst, facilitating the effective improvement of catalytic activity towards the ORR with a direct four-electron transfer pathway. The excellent ORR activity may be mainly attributed to high contents of graphitic N, pyridinic-N, and Co-N configurations. This study opens a new way to rationally design cheap and active ORR catalysts by using simple flat compound as a direct template.

  3. Nanocrystal conversion chemistry: A unified and materials-general strategy for the template-based synthesis of nanocrystalline solids

    SciTech Connect

    Vasquez, Yolanda; Henkes, Amanda E.; Chris Bauer, J.; Schaak, Raymond E.

    2008-07-15

    The concept of nanocrystal conversion chemistry, which involves the use of pre-formed nanoparticles as templates for chemical transformation into derivative solids, has emerged as a powerful approach for designing the synthesis of complex nanocrystalline solids. The general strategy exploits established synthetic capabilities in simple nanocrystal systems and uses these nanocrystals as templates that help to define the composition, crystal structure, and morphology of product nanocrystals. This article highlights key examples of 'conversion chemistry' approaches to the synthesis of nanocrystalline solids using a variety of techniques, including galvanic replacement, diffusion, oxidation, and ion exchange. The discussion is organized according to classes of solids, highlighting the diverse target systems that are accessible using similar chemical concepts: metals, oxides, chalcogenides, phosphides, alloys, intermetallic compounds, sulfides, and nitrides. - Graphical abstract: Nanocrystal conversion chemistry uses pre-formed nanoparticles as templates for chemical transformation into derivative solids, helping to define the composition, crystal structure, and morphology of product nanocrystals that have more complex features than their precursor templates. This article highlights the application of this concept to diverse classes of solids, including metals, oxides, chalcogenides, phosphides, alloys, intermetallics, sulfides, and nitrides.

  4. 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

  5. Template-Directed Synthesis of Nanoparticles

    NASA Astrophysics Data System (ADS)

    You, Eun-Ah

    The physical and optical properties of the particles can be tuned by the rational design of nanoparticles (NPs)---the ability to select, in advance, desired particle geometry. In particular, template-directed synthesis can define the geometry of NPs with precise control over the size and shape of individual particles over a wide range of dimensions. This dissertation describes different approaches to create geometry-controlled particles. First, we generated multiscale Au NPs spanning multiple length scales (e.g. >100 nm dimensions, >10 nm thin shells/components, and >1 nm sharp features) with different aspect ratios ranging from 1.0 to 7.7 using Si templates. Three dimensional (3D) multiscale Au particles showed that increasing the length of the particles resulted in excitation of a longitudinal mode and two different transverse modes having different multipolar orders. The multipolar orders increased for both longitudinal and transverse modes as the aspect ratio increased. Finite-difference time-domain calculations revealed that the structural asymmetry of the 3D anisotropic particles resulted in two distinct transverse plasmon resonances. When the 3D structural change occurred at the ends of the multiscale particle, however, the optical response showed two resonances in the longitudinal direction and only a single resonance in the transverse direction. Second, we created arsenic trioxide (ATO) nanoparticles using nanowell templates. The different sizes of ATO nanocrystals were generated by controlling the concentration of the precursor materials while keeping the well volume the same. Selected area electron diffraction showed that the nanoparticles are single crystalline. Furthermore, the biological activity of ATO nanocrystals as anticancer drug was tested by investigating their cytotoxicity. We found that ATO nanocrystals have a modestly attenuated activity compared to free ATO. Finally, we synthesized Au nanospheres with size control and functionalized the

  6. 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

  7. Business planning: a template for success.

    PubMed

    Dye, Judy

    2002-01-01

    Because managing a laboratory, or any health-care entity, is as much a business as a service, it is important for you to have a good grasp on how you can take opportunities from idea conception to implementation to assessment/revision. Regardless of the size of your proposed project, you need to consider a number of factors, among them: your history and what opportunities you can seize from your strengths and weaknesses; the overall business climate; anticipated costs; staff involvement; how you will market your project; and what measures to use to determine your success. Above all else, you need to set goals, both ultimate and intermediate, to instill focus, incentive, and a sense of achievement. The next time someone on your staff says, "Why don't we try that?," refer to this Template Topic. It can serve as a tool to help you determine whether you should try "that" and be the compass that helps guide your efforts.

  8. Using archetypes for defining CDA templates.

    PubMed

    Moner, David; Moreno, Alberto; Maldonado, José A; Robles, Montserrat; Parra, Carlos

    2012-01-01

    While HL7 CDA is a widely adopted standard for the documentation of clinical information, the archetype approach proposed by CEN/ISO 13606 and openEHR is gaining recognition as a means of describing domain models and medical knowledge. This paper describes our efforts in combining both standards. Using archetypes as an alternative for defining CDA templates permit new possibilities all based on the formal nature of archetypes and their ability to merge into the same artifact medical knowledge and technical requirements for semantic interoperability of electronic health records. We describe the process followed for the normalization of existing legacy data in a hospital environment, from the importation of the HL7 CDA model into an archetype editor, the definition of CDA archetypes and the application of those archetypes to obtain normalized CDA data instances.

  9. Controlling template erosion with advanced cleaning methods

    NASA Astrophysics Data System (ADS)

    Singh, SherJang; Yu, Zhaoning; Wähler, Tobias; Kurataka, Nobuo; Gauzner, Gene; Wang, Hongying; Yang, Henry; Hsu, Yautzong; Lee, Kim; Kuo, David; Dress, Peter

    2012-03-01

    We studied the erosion and feature stability of fused silica patterns under different template cleaning conditions. The conventional SPM cleaning is compared with an advanced non-acid process. Spectroscopic ellipsometry optical critical dimension (SE-OCD) measurements were used to characterize the changes in pattern profile with good sensitivity. This study confirmed the erosion of the silica patterns in the traditional acid-based SPM cleaning mixture (H2SO4+H2O2) at a rate of ~0.1nm per cleaning cycle. The advanced non-acid clean process however only showed CD shift of ~0.01nm per clean. Contamination removal & pattern integrity of sensitive 20nm features under MegaSonic assisted cleaning is also demonstrated.

  10. Nanoporous alumina as templates for multifunctional applications

    NASA Astrophysics Data System (ADS)

    Sousa, C. T.; Leitao, D. C.; Proenca, M. P.; Ventura, J.; Pereira, A. M.; Araujo, J. P.

    2014-09-01

    Due to its manufacturing and size tailoring ease, porous anodic alumina (PAA) templates are an elegant physical-chemical nanopatterning approach and an emergent alternative to more sophisticated and expensive methods currently used in nanofabrication. In this review, we will describe the ground work on the fabrication methods of PAA membranes and PAA-based nanostructures. We will present the specificities of the electrochemical growth processes of multifunctional nanomaterials with diversified shapes (e.g., nanowires and nanotubes), and the fabrication techniques used to grow ordered nanohole arrays. We will then focus on the fabrication, properties and applications of magnetic nanostructures grown on PAA and illustrate their dependence on internal (diameter, interpore distance, length, composition) and external (temperature and applied magnetic field intensity and direction) parameters. Finally, the most outstanding experimental findings on PAA-grown nanostructures and their trends for technological applications (sensors, energy harvesting, metamaterials, and biotechnology) will be addressed.

  11. 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

  12. Facile synthesis of porous TiO2 photocatalysts using waste sludge as the template

    NASA Astrophysics Data System (ADS)

    Wang, Xiaopeng; Huang, Shouqiang; Zhu, Nanwen; Lou, Ziyang; Yuan, Haiping

    2015-12-01

    A resource utilization method of waste sludge is present by the synthesis of waste sludge templated TiO2 photocatalysts. The organic materials in waste sludge are used as the pore-forming agents, and the transition metals included in the remaining waste sludge through calcination (WSC) can serve as the dopants for the WSC-TiO2 (WSCT) photocatalyst. The visible and UV-visible light driven photocatalytic activities of WSCT are much better compared to those of pure TiO2 and WSC, and it is originated from the higher light absorption property and the efficient electron-hole pair separation provided by waste sludge.

  13. 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.

  14. 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.

  15. 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,…

  16. 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...

  17. Non-enzymatic template-directed synthesis on RNA random copolymers - Poly(C, U) templates

    NASA Technical Reports Server (NTRS)

    Joyce, G. F.; Inoue, T.; Orgel, L. E.

    1984-01-01

    Random copolymer templates containing cytosine and uracil in ratios of 3:1 and 1:1 are used to explore the optimum conditions for efficient synthesis of guanine and adenine-containing oligonucleotides. The experimental procedure is described, including the preparation of mononucleoside 5'-phospho-2-methylimidazolides and random copolymers, the template-directed oligomerization, the removal and reintroduction of mononucleotides in interrupted reactions, the determination of oligomerization efficiency, the alkaline and enzymatic hydrolysis of reaction products, and the column chromatography. Results are presented and discussed for the dependence of adenine incorporation on the formation of short oligo(G)s, optimization of incorporation efficiencies by adjusting monomer concentrations, the characterization of oligomeric product distribution, and the regiospecificity of adenine incorporation. The prebiotic significance of the results is assessed.

  18. 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.

  19. Properties of ordered titanium templates covered with Au thin films for SERS applications

    NASA Astrophysics Data System (ADS)

    Grochowska, Katarzyna; Siuzdak, Katarzyna; Sokołowski, Michał; Karczewski, Jakub; Szkoda, Mariusz; Śliwiński, Gerard

    2016-12-01

    Currently, roughened metal nanostructures are widely studied as highly sensitive Raman scattering substrates that show application potential in biochemistry, food safety or medical diagnostic. In this work the structural properties and the enhancement effect due to surface enhanced Raman scattering (SERS) of highly ordered nano-patterned titanium templates covered with thin (5-20 nm) gold films are reported. The templates are formed by preparation of a dense structure of TiO2 nanotubes on a flat Ti surface (2 × 2 cm2) and their subsequent etching down to the substrate. SEM images reveal the formation of honeycomb nanostructures with the cavity diameter of 80 nm. Due to the strongly inhomogeneous distribution of the electromagnetic field in the vicinity of the Au film discontinuities the measured average enhancement factor (107-108) is markedly higher than observed for bare Ti templates. The enhancement factor and Raman signal intensity can be optimized by adjusting the process conditions and thickness of the deposited Au layer. Results confirm that the obtained structures can be used in surface enhanced sensing.

  20. 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