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Sample records for bacterial nanowires produced

  1. Electrical conductivity measurements of bacterial nanowires from Pseudomonas aeruginosa

    Science.gov (United States)

    Maruthupandy, Muthusamy; Anand, Muthusamy; Maduraiveeran, Govindhan; Sait Hameedha Beevi, Akbar; Jeeva Priya, Radhakrishnan

    2015-12-01

    The extracellular appendages of bacteria (flagella) that transfer electrons to electrodes are called bacterial nanowires. This study focuses on the isolation and separation of nanowires that are attached via Pseudomonas aeruginosa bacterial culture. The size and roughness of separated nanowires were measured using transmission electron microscopy (TEM) and atomic force microscopy (AFM), respectively. The obtained bacterial nanowires indicated a clear image of bacterial nanowires measuring 16 nm in diameter. The formation of bacterial nanowires was confirmed by microscopic studies (AFM and TEM) and the conductivity nature of bacterial nanowire was investigated by electrochemical techniques. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), which are nondestructive voltammetry techniques, suggest that bacterial nanowires could be the source of electrons—which may be used in various applications, for example, microbial fuel cells, biosensors, organic solar cells, and bioelectronic devices. Routine analysis of electron transfer between bacterial nanowires and the electrode was performed, providing insight into the extracellular electron transfer (EET) to the electrode. CV revealed the catalytic electron transferability of bacterial nanowires and electrodes and showed excellent redox activities. CV and EIS studies showed that bacterial nanowires can charge the surface by producing and storing sufficient electrons, behave as a capacitor, and have features consistent with EET. Finally, electrochemical studies confirmed the development of bacterial nanowires with EET. This study suggests that bacterial nanowires can be used to fabricate biomolecular sensors and nanoelectronic devices.

  2. Bacterial Nanowires: Is the Subsurface Hardwired?

    Science.gov (United States)

    Gorby, Y. A.; Davis, C. A.; Atekwana, E.

    2006-05-01

    Bacteria, ranging from oxygenic photosynthetic cyanobacteria to heterotrophic sulfate reducing bacteria, produce electrically-conductive appendages referred to as bacterial nanowires. Dissimilatory metal reducing bacteria, including Shewanella oneidensis and Geobacter sulfurreducens, produce electrically conductive nanowires in direct response to electron acceptor limitation and facilitate electron transfer to solid phase iron oxides. Nanowires produced by S. oneidensis strain MR-1, which served as our primary model organism, are functionalized by decaheme cytochromes MtrC and OmcA that are distributed along the length of the nanowires. Mutants deficient in MtrC and OmcA produce nanowires that were poorly conductive. These mutants also differ from wild type cells in their ability to reduce solid phase iron oxides, to produce electrical current in a mediator less microbial fuel cell, and to form complex biofilms at air liquid interfaces. Recent results obtained using direct cell counts and low frequency electrical measurements demonstrate that microbial growth correlated with real and imaginary electrical conductivity response in uncoated silica sand columns. Direct observation of packing material with environmental scanning electron microscopy (ESEM) revealed a fine network of extracellular structures that were morphologically similar to nanowires observed in metal reducing bacteria. No such structures were observed in control columns. We hypothesize that microbial nanowires may in part be responsible for the electrical response observed in the biostimulated columns.

  3. New Applications of Electrochemically Produced Porous Semiconductors and Nanowire Arrays

    Directory of Open Access Journals (Sweden)

    Leisner Malte

    2010-01-01

    Full Text Available Abstract The growing demand for electro mobility together with advancing concepts for renewable energy as primary power sources requires sophisticated methods of energy storage. In this work, we present a Li ion battery based on Si nanowires, which can be produced reliable and cheaply and which shows superior properties, such as a largely increased capacity and cycle stability. Sophisticated methods based on electrochemical pore etching allow to produce optimized regular arrays of nanowires, which can be stabilized by intrinsic cross-links, which serve to avoid unwanted stiction effects and allow easy processing.

  4. Structure of the Type IVa Major Pilin from the Electrically Conductive Bacterial Nanowires of Geobacter sulfurreducens

    Energy Technology Data Exchange (ETDEWEB)

    Reardon, Patrick N.; Mueller, Karl T.

    2013-10-11

    Several species of bacteria are capable of reducing insoluble metal oxides as well as other extracellular electron acceptors. These bacteria play a critical role in the cycling of minerals in subsurface environments, sediments, and groundwater. In some species of bacteria, such as Geobacter sulfurreducens, the transport of electrons is facilitated by filamentous fibers that are referred to as bacterial nanowires. These nanowires belong to the type IVa family of pilin proteins and are mainly comprised of one subunit protein, PilA. Here, we report the high resolution solution nuclear magnetic resonance (NMR) structure of the PilA protein from G. sulfurreducens determined in detergent micelles. The protein is over 85% α-helical and exhibits similar architecture to the N-terminal regions of other non-conductive type IVa pilins. The detergent micelle interacts with the first 21 amino acids of the protein, indicating that this region likely associates with the bacterial inner membrane prior to fiber formation. A model of the G. sulfurreducens pilus fiber is proposed based on docking of this structure into the fiber model of the type IVa pilin from Neisseria gonorrhoeae. This model provides insight into the organization of aromatic amino acids that are important for electrical conduction.

  5. Preparation and dielectric properties of SiC nanowires self-sacrificially templated by carbonated bacterial cellulose

    International Nuclear Information System (INIS)

    Graphical abstract: Display Omitted Highlights: ► A new material – CBC is introduced as a template to prepare SiC nanowires. ► SiC nanowires are synthesized by the infiltration process of reactive vapor Si. ► The highest ε″ of β-SiC nanowires is obtained at 1400 °C. -- Abstract: SiC nanowires were synthesized by the infiltration process of reactive vapor Si in Ar atmosphere at 1350–1450 °C, using carbonated bacterial cellulose (CBC) as carbon template and a reactant. Scanning electron microscopy (SEM), powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and vector network analyzer were employed to characterize the samples. The diameter of the resulting β-SiC nanowires changes with calcination temperatures, specifically, 35–60 nm for 1350 °C, 40–80 nm for 1400 °C, and 30–60 nm for 1450 °C. The β-SiC nanowires obtained at 1400 °C possess the highest ε″ of complex permittivity.

  6. Preparation and dielectric properties of SiC nanowires self-sacrificially templated by carbonated bacterial cellulose

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Lixia; Ma, Yongjun; Dai, Bo [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Zhou, Yong [Eco-materials and Renewable Energy Research Center (ERERC), School of Physics, National Lab of Solid State Microstructure, ERERC, Nanjing University, Nanjing 210093 (China); Liu, Jinsong [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Pei, Chonghua, E-mail: peichonghua@swust.edu.cn [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China)

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► A new material – CBC is introduced as a template to prepare SiC nanowires. ► SiC nanowires are synthesized by the infiltration process of reactive vapor Si. ► The highest ε″ of β-SiC nanowires is obtained at 1400 °C. -- Abstract: SiC nanowires were synthesized by the infiltration process of reactive vapor Si in Ar atmosphere at 1350–1450 °C, using carbonated bacterial cellulose (CBC) as carbon template and a reactant. Scanning electron microscopy (SEM), powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and vector network analyzer were employed to characterize the samples. The diameter of the resulting β-SiC nanowires changes with calcination temperatures, specifically, 35–60 nm for 1350 °C, 40–80 nm for 1400 °C, and 30–60 nm for 1450 °C. The β-SiC nanowires obtained at 1400 °C possess the highest ε″ of complex permittivity.

  7. A laser-assisted process to produce patterned growth of vertically aligned nanowire arrays for monolithic microwave integrated devices

    Science.gov (United States)

    Van Kerckhoven, Vivien; Piraux, Luc; Huynen, Isabelle

    2016-06-01

    An experimental process for the fabrication of microwave devices made of nanowire arrays embedded in a dielectric template is presented. A pulse laser process is used to produce a patterned surface mask on alumina templates, defining precisely the wire growing areas during electroplating. This technique makes it possible to finely position multiple nanowire arrays in the template, as well as produce large areas and complex structures, combining transmission line sections with various nanowire heights. The efficiency of this process is demonstrated through the realisation of a microstrip electromagnetic band-gap filter and a substrate-integrated waveguide.

  8. A laser-assisted process to produce patterned growth of vertically aligned nanowire arrays for monolithic microwave integrated devices.

    Science.gov (United States)

    Kerckhoven, Vivien Van; Piraux, Luc; Huynen, Isabelle

    2016-06-10

    An experimental process for the fabrication of microwave devices made of nanowire arrays embedded in a dielectric template is presented. A pulse laser process is used to produce a patterned surface mask on alumina templates, defining precisely the wire growing areas during electroplating. This technique makes it possible to finely position multiple nanowire arrays in the template, as well as produce large areas and complex structures, combining transmission line sections with various nanowire heights. The efficiency of this process is demonstrated through the realisation of a microstrip electromagnetic band-gap filter and a substrate-integrated waveguide. PMID:27138863

  9. Membrane fatty acids as markers of bacterial antibiotic-producers

    Czech Academy of Sciences Publication Activity Database

    Elhottová, Dana; Petrásek, Jiří; Krištůfek, Václav; Jágr, Michal; Chroňáková, Alica; Petříček, Miroslav

    Cairns : International Society for Microbial Ecology, 2008. [International Symposium on Microbial Ecology ISME 12. Microbial Diversity - Sustaining the Blue Planet /12./. 17.08.2008-22.08.2008, Cairns] R&D Projects: GA AV ČR IAA600660607; GA MŠk 2B06154 Institutional research plan: CEZ:AV0Z60660521; CEZ:AV0Z50200510 Keywords : membrane fatty acids * bacterial antibiotic -producers * microorganisms Subject RIV: EH - Ecology, Behaviour

  10. Controlled size, structure, and morphology of nanowires produced by single particle nano-fabrication technique (SPNT)

    International Nuclear Information System (INIS)

    Cross-linking reaction of the polymers was firstly promoted by charged particle irradiation to the thin films in the present study. Non-homogeneous cross-linking reaction in the polymers gives clear nanowires whose size, length, and number density are fairly controlled by selecting particles, molecular weights, etc. Electronic conductive nanowires were produced by the present technique, as well as achieving the formation of SiC ceramic nanowires by the combined processes of SPNT and subsequent sintering at ultra-high temperature. It is also demonstrated that the morphology of the final nanostructure is customized by appropriate selection of the ion fluence, combination of polymers, and the solvent employed for development. Octopus-like nanostructures consisting of a tangled hydrophilic polymer core and splayed hydrophobic polymer segments are successfully produced as an example of the process. The present technique provides universal feasibility for the formation of nanostructures based on 'any' polymer materials in which radiations induce crosslinking reactions. (author)

  11. Produced water exposure alters bacterial response to biocides.

    Science.gov (United States)

    Vikram, Amit; Lipus, Daniel; Bibby, Kyle

    2014-11-01

    Microbial activity during the holding and reuse of wastewater from hydraulic fracturing operations, termed produced water, may lead to issues with corrosion, sulfide release, and fouling. Biocides are applied to control biological activity, often with limited efficacy, which is typically attributed to chemical interactions with the produced water. However, it is unknown whether there is a biologically driven mechanism to biocide tolerance in produced water. Here, we demonstrate that produced water exposure results in an enhanced tolerance against the typically used biocide glutaraldehyde and increased susceptibility to the oxidative biocide hypochlorite in a native and a model bacteria and that this altered resistance is due to the salinity of the produced water. In addition, we elucidate the genetic response of the model organism Pseudomonas fluorescens to produced water exposure to provide a mechanistic interpretation of the altered biocide resistance. The RNA-seq data demonstrated the induction of genes involved in osmotic stress, energy production and conversion, membrane integrity, and protein transport following produced water exposure, which facilitates bacterial survival and alters biocide tolerance. Efforts to fundamentally understand biocide resistance mechanisms, which enable the optimization of biocide application, hold significant implications for greening of the fracturing process through encouraging produced water recycling. Specifically, these results suggest the necessity of optimizing biocide application at the level of individual shale plays, rather than historical experience, based upon produced water characteristics and salinity. PMID:25279933

  12. Frequency of Bacterial Frequency of Bacterial Contamination in Traditional Ice Cream Produced in Arak, Iran (2011)

    OpenAIRE

    M. Rezaei; Ghasemi khah , R. (PhD); M. Parviz; Zarei, D. (MSc

    2014-01-01

    Background and Objective: Ice cream is a suitable environment for microbial growth due to its chemical structure, ingredients, and its increased supply and demand. In the absence of hygienic considerations, it can cause poisoning. This study aimed to determine bacterial contamination in traditional ice cream produced in Arak city in 2011. Material and Methods: The samples (n= 30) were randomly obtained from different parts of Arak in, 2011. The Samples were shipped in cold conditions and tota...

  13. Frequency of Bacterial Frequency of Bacterial Contamination in Traditional Ice Cream Produced in Arak, Iran (2011

    Directory of Open Access Journals (Sweden)

    Rezaei, M. (MSc

    2014-05-01

    Full Text Available Background and Objective: Ice cream is a suitable environment for microbial growth due to its chemical structure, ingredients, and its increased supply and demand. In the absence of hygienic considerations, it can cause poisoning. This study aimed to determine bacterial contamination in traditional ice cream produced in Arak city in 2011. Material and Methods: The samples (n= 30 were randomly obtained from different parts of Arak in, 2011. The Samples were shipped in cold conditions and total count of microorganisms test was performed according to Iranian national standards. Results: In 16.66%, the microbial contamination was below the limit of microbial load (5×104, and in 83.3% the contamination was more than allowed level. Conclusion: This study highlights the dire situation for bacterial contamination of traditional ice cream in Arak city. Keywords: Arak, Ice Cream, Microbial Contamination

  14. Semiconductor nanowire thermoelectric materials and devices, and processes for producing same

    Science.gov (United States)

    Lagally, Max G.; Evans, Paul G.; Ritz, Clark S.

    2011-02-15

    The present invention provides nanowires and nanoribbons that are well suited for use in thermoelectric applications. The nanowires and nanoribbons are characterized by a periodic longitudinal modulation, which may be a compositional modulation or a strain-induced modulation. The nanowires are constructed using lithographic techniques from thin semiconductor membranes, or "nanomembranes."

  15. Semiconductor nanowire thermoelectric materials and devices, and processes for producing same

    Energy Technology Data Exchange (ETDEWEB)

    Lagally, Max G.; Evans, Paul G.; Ritz, Clark S.

    2015-11-17

    The present invention provides nanowires and nanoribbons that are well suited for use in thermoelectric applications. The nanowires and nanoribbons are characterized by a periodic compositional longitudinal modulation. The nanowires are constructed using lithographic techniques from thin semiconductor membranes, or "nanomembranes."

  16. Silica coating of polymer nanowires produced via nanoimprint lithography from femtosecond laser machined templates

    Science.gov (United States)

    Rajput, Deepak; Costa, Lino; Terekhov, Alexander; Lansford, Kathleen; Hofmeister, William

    2012-03-01

    In this paper we report on the fabrication of regular arrays of silica nanoneedles by deposition of a thin layer of silica on patterned arrays of polymer nanowires (or polymer nanohair). An array of high-aspect-ratio nanoscale diameter holes of depths greater than 10 µm was produced at the surface of a fused silica wafer by an amplified femtosecond laser system operated in single-pulse mode. Cellulose acetate (CA) film was imprinted into the nanoholes and peeled off to form a patterned array of standing CA nanowires, a negative replica of the laser machined nanoholes. The cellulose acetate replica was then coated with silica in a chemical vapor deposition process using silicon tetrachloride vapor at 65 °C. Field emission scanning electron microscopy, focused ion beam sectioning, energy dispersive x-ray analysis and Fourier-transform infrared spectroscopy were used to characterize the silica nanoneedles. Precisely patterned, functionalized arrays of standing silica nanoneedles are useful for a number of applications.

  17. Overgrowth of GaN on GaN nanowires produced by mask-less etching

    Science.gov (United States)

    Frajtag, P.; Hosalli, A. M.; Samberg, J. P.; Colter, P. C.; Paskova, T.; El-Masry, N. A.; Bedair, S. M.

    2012-08-01

    We report on the generation of GaN nanowires (NWs) using mask-less reactive ion etching (RIE). The NWs are believed to be the result of a high etching rate in regions where a high dislocation density is present in the GaN films grown on sapphire substrates. We have studied the effect of defect densities in the original GaN films and its relation to the generation of these NWs. We show that defect reduction in the overgrown GaN is related to the presence of a network of embedded voids generated between these nanowires during the regrowth on the etched nanowires. We show that further reduction in dislocation density can be achieved by repeating the process of nanowire generation and overgrowth. Also we report on the residual strain and curvature in GaN after the first and second embedded voids approach (EVA).

  18. 利用市售不锈钢箔制备氮化硼纳米线%Boron Nitride Nanowires Produced on Commercial Stainless Steel foil

    Institute of Scientific and Technical Information of China (English)

    陈拥军; 童张法; 骆丽杰

    2008-01-01

    Chemical vapor deposition growth of one-dimensional nanomaterials usually demands substrates that have been coated with a layer of catalyst film. In this study, a green process to synthesize boron nitride (BN) nanowires directly on commercial stainless steel foils was proposed by heating boron and zinc oxide powders under a mixture gas flow of N2 and 15% H2 at 1100℃, and a large quantities of pure h-BN nanowires have been produced directly on commercial stainless steel foil. The stainless steel foils not only acted as the substrate but also the catalyst for the nanowire growth. The synthesized BN nanowires were characterized by X-ray diffraction, scanning and transmission electron microscopes, X-ray energy dispersive spectrometer and photoluminescence spectroscopy. The nanowires also possess strong PL emission bands at 515, 535, and 728nm.

  19. Influence of anerobic fungi of biogas producing bacterial community

    Czech Academy of Sciences Publication Activity Database

    Mrázek, Jakub; Štrosová, Lenka; Fliegerová, Kateřina

    Aberdeen : Rowett Institute -INRA, 2010. s. 1-1. [7th joint symposium of Rowett - INRA. 23.06. - 25.06.2010, Aberdeen] R&D Projects: GA ČR GPP503/10/P394; GA ČR GD525/08/H060 Institutional research plan: CEZ:AV0Z50450515 Keywords : anaerobic fungi * biogas * bacterial community Subject RIV: EE - Microbiology, Virology

  20. Nano-biosensor development for bacterial detection during human kidney infection: use of glycoconjugate-specific antibody-bound gold NanoWire arrays (GNWA).

    Science.gov (United States)

    Basu, Manju; Seggerson, Sara; Henshaw, Joshua; Jiang, Juan; del A Cordona, Rocio; Lefave, Clare; Boyle, Patrick J; Miller, Albert; Pugia, Michael; Basu, Subhash

    2004-01-01

    Infectious disease, commonly caused by bacterial pathogens, is now the world's leading cause of premature death and third overall cause behind cardiovascular disease and cancer. Urinary Tract Infection (UTI), caused by E. coli bacteria, is a very common bacterial infection, a majority in women (85%) and may result in severe kidney failure if not detected quickly. Among hundreds of strains the bacteria, E. coli 0157:H7, is emerging as the most aggressive one because of its capability to produce a toxin causing hemolytic uremic syndrome (HUS) resulting in death, especially in children. In the present study, a project has been undertaken for developing a rapid method for UTI detection in very low bacteria concentration, applying current knowledge of nano-technology. Experiments have been designed for the development of biosensors using nano-fabricated structures coated with elements such as gold that have affinity for biomolecules. A biosensor is a device in which a biological sensing element is either intimately connected to or integrated within a transducer. The basic principle for the detection procedure of the infection is partly based on the enzyme-linked immunosorbent assay system. Anti-E. coli antibody-bound Gold Nanowire Arrays (GNWA) prepared on anodized porous alumina template is used for the primary step followed by binding of the bacteria containing specimen. An alkaline phosphatase-conjugated second antibody is then added to the system and the resultant binding determined by both electrochemical and optical measurements. Various kinds of GNWA templates were used in order to determine the one with the best affinity for antibody binding. In addition, an efficient method for enhanced antibody binding has been developed with the covalent immobilization of an organic linker Dithiobissuccinimidylundecanoate (DSU) on the GNWA surface. Studies have also been conducted to optimize the antibody-binding conditions to the linker-attached GNWA surfaces for their

  1. Methods of producing protoporphyrin IX and bacterial mutants therefor

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Jizhong; Qiu, Dongru; He, Zhili; Xie, Ming

    2016-03-01

    The presently disclosed inventive concepts are directed in certain embodiments to a method of producing protoporphyrin IX by (1) cultivating a strain of Shewanella bacteria in a culture medium under conditions suitable for growth thereof, and (2) recovering the protoporphyrin IX from the culture medium. The strain of Shewanella bacteria comprises at least one mutant hemH gene which is incapable of normal expression, thereby causing an accumulation of protoporphyrin IX. In certain embodiments of the method, the strain of Shewanella bacteria is a strain of S. loihica, and more specifically may be S. loihica PV-4. In certain embodiments, the mutant hemH gene of the strain of Shewanella bacteria may be a mutant of shew_2229 and/or of shew_1140. In other embodiments, the presently disclosed inventive concepts are directed to mutant strains of Shewanella bacteria having at least one mutant hemH gene which is incapable of normal expression, thereby causing an accumulation of protoporphyrin IX during cultivation of the bacteria. In certain embodiments the strain of Shewanella bacteria is a strain of S. loihica, and more specifically may be S. loihica PV-4. In certain embodiments, the mutant hemH gene of the strain of Shewanella bacteria may be a mutant of shew_2229 and/or shew_1140.

  2. Biodegradable films produced from the bacterial polysaccharide FucoPol.

    Science.gov (United States)

    Ferreira, Ana R V; Torres, Cristiana A V; Freitas, Filomena; Reis, Maria A M; Alves, Vítor D; Coelhoso, Isabel M

    2014-11-01

    FucoPol, an exopolysaccharide produced by Enterobacter A47, grown in bioreactor with glycerol as carbon source, was used with citric acid to obtain biodegradable films by casting. The films were characterized in terms of optical, hygroscopic, mechanical and barrier properties. These films have shown to be transparent, but with a brown tone, imparting small colour changes when applied over coloured surfaces. They were hydrophilic, with high permeability to water vapour (1.01×10(-11)mol/msPa), but presented good barrier properties to oxygen and carbon dioxide (0.7×10(-16)molm/m(2)sPa and 42.7×10(-16)molm/m(2)sPa, respectively). Furthermore, films have shown mechanical properties under tensile tests characteristic of ductile films with high elongation at break, low tension at break and low elastic modulus. Although the obtained results are promising, films properties can be improved, namely by testing alternative plasticizers, crosslinking agents and blends with other biopolymers. Taking into account the observed ductile mechanical properties, good barrier properties to gases when low water content is used and their hydrophilic character, it is foreseen a good potential for FucoPol films to be incorporated as inner layer of a multilayer packaging material. PMID:24769364

  3. Ultrasharp Si nanowires produced by plasma-enhanced chemical vapor deposition

    Czech Academy of Sciences Publication Activity Database

    Červenka, Jiří; Ledinský, Martin; Stuchlíková, The-Ha; Stuchlík, Jiří; Výborný, Zdeněk; Holovský, Jakub; Hruška, Karel; Fejfar, Antonín; Kočka, Jan

    2010-01-01

    Roč. 4, 1-2 (2010), s. 37-39. ISSN 1862-6254 R&D Projects: GA MŠk(CZ) LC06040; GA AV ČR KAN400100701; GA MŠk LC510 Institutional research plan: CEZ:AV0Z10100521 Keywords : nanowires * silicon * scanning electron microscopy * hemical vapor deposition * Raman spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.660, year: 2010 http://www3.interscience.wiley.com/cgi-bin/fulltext/123213957/HTMLSTART

  4. Bacterial Growth on Photochemically Transformed Leachates from Aquatic and Terrestrial Primary Producers

    DEFF Research Database (Denmark)

    Anesio, A.M.; Nielsen, Jon Theil; Granéli, W.

    2000-01-01

    We measured bacterial growth on phototransformed dissolved organic matter (DOM) leached from eight different primary producers. Leachates (10 mg C liter-1) were exposed to artificial UVA + UVB radiation, or kept in darkness, for 20 h. DOM solutions were subsequently inoculated with lake water...... leachate and type of bacterial growth criterion. Bacterial carbon utilization (biomass production plus respiration) over the entire incubation period (120 h) was enhanced by UV radiation of leachate from the terrestrial leaves, relative to carbon utilization in non-irradiated leachates. Conversely, carbon...... utilization was reduced by radiation of the leachates from aquatic macrophytes. In a separate experiment, the stable C and N isotope composition of bacteria grown on irradiated and non-irradiated DOM was estimated. Bacterial growth on UV-irradiated DOM was enriched in 13C relative to the bacteria in the non...

  5. Bacterial Canker (Clavibacter michiganensis subsp. michiganensis) of tomato in commercial seed produced in Indonesia

    NARCIS (Netherlands)

    Anwar, A.; Zouwen, van der P.S.; Ilyas, S.; Wolf, van der J.M.

    2004-01-01

    In 2002, Clavibacter michiganensis subsp. michiganensis (Smith) Davis, the causal organism of bacterial canker of tomato (Lycopersicon esculentum), was isolated from two of six commercial asymptomatic tomato seed lots produced on Java in Indonesia. C. michiganensis subsp. michiganensis has not been

  6. 3D plasmonic transducer based on gold nanoparticles produced by laser ablation on silica nanowires

    Science.gov (United States)

    Gontad, F.; Caricato, A. P.; Manera, M. G.; Colombelli, A.; Resta, V.; Taurino, A.; Cesaria, M.; Leo, C.; Convertino, A.; Klini, A.; Perrone, A.; Rella, R.; Martino, M.

    2016-05-01

    Silica two-dimensional substrates and nanowires (NWs) forests have been successfully decorated with Au nanoparticles (NPs) through laser ablation by using a pulsed ArF excimer laser, for sensor applications. A uniform coverage of both substrate surfaces with NPs has been achieved controlling the number of laser pulses. The annealing of the as-deposited particles resulted in a uniform well-defined distribution of spherical NPs with an increased average diameter up to 25 nm. The deposited samples on silica NWs forest present a very good plasmonic resonance which resulted to be very sensitive to the changes of the environment (ethanol/water solutions with increasing concentration of ethanol) allowing the detection of changes on the second decimal digit of the refractive index, demonstrating its potentiality for further biosensing functionalities.

  7. Nanowire Growth for Photovoltaics

    DEFF Research Database (Denmark)

    Holm, Jeppe Vilstrup

    Solar cells commercial success is based on an efficiency/cost calculation. Nanowire solar cells is one of the foremost candidates to implement third generation photo voltaics, which are both very efficient and cheap to produce. This thesis is about our progress towards commercial nanowire solar...... cells. Resonance effects between the light and nanowire causes an inherent concentration of the sunlight into the nanowires, and means that a sparse array of nanowires (less than 5% of the area) can absorb all the incoming light. The resonance effects, as well as a graded index of refraction, also traps...... the light. The concentration and light trapping means that single junction nanowire solar cells have a higher theoretical maximum efficiency than equivalent planar solar cells. We have demonstrated the built-in light concentration of nanowires, by growing, contacting and characterizing a solar cell...

  8. Antibacterial synergy of curcumin with antibiotics against biofilm producing clinical bacterial isolates

    Science.gov (United States)

    Kali, Arunava; Bhuvaneshwar, Devaraj; Charles, Pravin M. V.; Seetha, Kunigal Srinivasaiah

    2016-01-01

    Introduction: The role of natural bioactive substances in treating infections has been rediscovered as bacterial resistance become common to most of the antibiotics. Curcumin is a bioactive substance from turmeric. Owing to antimicrobial properties, its prospect as an antibacterial agent is currently under focus. Materials and Methods: We have evaluated the in vitro synergy of curcumin with antibiotics against sixty biofilm producing bacterial isolates. Congo red agar method was used to identify the biofilm producing isolates. Curcumin minimum inhibitory concentration (MIC) was determined by agar dilution method. Its antibiotic synergy was identified by the increase in disc diffusion zone size on Mueller-Hinton agar with 32 mg/L curcumin. Results: The mean MICs of curcumin against Gram-positive and Gram-negative isolates were 126.9 mg/L and 117.4 mg/L, respectively. Maximum synergy was observed with ciprofloxacin among Gram-positive and amikacin, gentamicin, and cefepime among Gram-negative isolates. Conclusions: Curcumin per se as well as in combination with other antibiotics has a demonstrable antibacterial action against biofilm producing bacterial isolates. It may have a beneficial role in supplementing antibiotic therapy. PMID:27330262

  9. No role for bacterially produced salicylic Acid in rhizobacterial induction of systemic resistance in Arabidopsis.

    Science.gov (United States)

    Ran, L X; van Loon, L C; Bakker, P A H M

    2005-11-01

    ABSTRACT The role of bacterially produced salicylic acid (SA) in the induction of systemic resistance in plants by rhizobacteria is far from clear. The strong SA producer Pseudomonas fluorescens WCS374r induces resistance in radish but not in Arabidopsis thaliana, whereas application of SA leads to induction of resistance in both plant species. In this study, we compared P. fluorescens WCS374r with three other SA-producing fluorescent Pseudomonas strains, P. fluorescens WCS417r and CHA0r, and P. aeruginosa 7NSK2 for their abilities to produce SA under different growth conditions and to induce systemic resistance in A. thaliana against bacterial speck, caused by P. syringae pv. tomato. All strains produced SA in vitro, varying from 5 fg cell(-1) for WCS417r to >25 fg cell(-1) for WCS374r. Addition of 200 muM FeCl(3) to standard succinate medium abolished SA production in all strains. Whereas the incubation temperature did not affect SA production by WCS417r and 7NSK2, strains WCS374r and CHA0r produced more SA when grown at 33 instead of 28 degrees C. WCS417r, CHA0r, and 7NSK2 induced systemic resistance apparently associated with their ability to produce SA, but WCS374r did not. Conversely, a mutant of 7NSK2 unable to produce SA still triggered induced systemic resistance (ISR). The possible involvement of SA in the induction of resistance was evaluated using SA-nonaccumulating transgenic NahG plants. Strains WCS417r, CHA0r, and 7NSK2 induced resistance in NahG Arabidopsis. Also, WCS374r, when grown at 33 or 36 degrees C, triggered ISR in these plants, but not in ethylene-insensitive ein2 or in non-plant pathogenesis- related protein-expressing npr1 mutant plants, irrespective of the growth temperature of the bacteria. These results demonstrate that, whereas WCS374r can be manipulated to trigger ISR in Arabidopsis, SA is not the primary determinant for the induction of systemic resistance against bacterial speck disease by this bacterium. Also, for the other

  10. Phonon processes in vertically aligned silicon nanowire arrays produced by low-cost all-solution galvanic displacement method

    Science.gov (United States)

    Banerjee, Debika; Trudeau, Charles; Gerlein, Luis Felipe; Cloutier, Sylvain G.

    2016-03-01

    The nanoscale engineering of silicon can significantly change its bulk optoelectronic properties to make it more favorable for device integration. Phonon process engineering is one way to enhance inter-band transitions in silicon's indirect band structure alignment. This paper demonstrates phonon localization at the tip of silicon nanowires fabricated by galvanic displacement using wet electroless chemical etching of a bulk silicon wafer. High-resolution Raman micro-spectroscopy reveals that such arrayed structures of silicon nanowires display phonon localization behaviors, which could help their integration into the future generations of nano-engineered silicon nanowire-based devices such as photodetectors and solar cells.

  11. Primordial soup was edible: abiotically produced Miller-Urey mixture supports bacterial growth.

    Science.gov (United States)

    Xie, Xueshu; Backman, Daniel; Lebedev, Albert T; Artaev, Viatcheslav B; Jiang, Liying; Ilag, Leopold L; Zubarev, Roman A

    2015-01-01

    Sixty years after the seminal Miller-Urey experiment that abiotically produced a mixture of racemized amino acids, we provide a definite proof that this primordial soup, when properly cooked, was edible for primitive organisms. Direct admixture of even small amounts of Miller-Urey mixture strongly inhibits E. coli bacteria growth due to the toxicity of abundant components, such as cyanides. However, these toxic compounds are both volatile and extremely reactive, while bacteria are highly capable of adaptation. Consequently, after bacterial adaptation to a mixture of the two most abundant abiotic amino acids, glycine and racemized alanine, dried and reconstituted MU soup was found to support bacterial growth and even accelerate it compared to a simple mixture of the two amino acids. Therefore, primordial Miller-Urey soup was perfectly suitable as a growth media for early life forms. PMID:26412575

  12. Engineering control of bacterial cellulose production using a genetic toolkit and a new cellulose-producing strain

    OpenAIRE

    Florea, Michael; Hagemann, Henrik; Santosa, Gabriella; Abbott, James; Micklem, Chris N.; Spencer-Milnes, Xenia; de Arroyo Garcia, Laura; Paschou, Despoina; Lazenbatt, Christopher; Kong, Deze; Chughtai, Haroon; Jensen, Kirsten; Freemont, Paul S.; Kitney, Richard; Reeve, Benjamin

    2016-01-01

    Bacterial cellulose is a remarkable material that is malleable, biocompatible, and over 10-times stronger than plant-based cellulose. It is currently used to create materials for tissue engineering, medicine, defense, electronics, acoustics, and fabrics. We describe here a bacterial strain that is readily amenable to genetic engineering and produces high quantities of bacterial cellulose in low-cost media. To reprogram this organism for biotechnology applications, we created a set of genetic ...

  13. Genome sequence and plasmid transformation of the model high-yield bacterial cellulose producer Gluconacetobacter hansenii ATCC 53582

    OpenAIRE

    Michael Florea; Benjamin Reeve; James Abbott; Freemont, Paul S.; Tom Ellis

    2016-01-01

    Bacterial cellulose is a strong, highly pure form of cellulose that is used in a range of applications in industry, consumer goods and medicine. Gluconacetobacter hansenii ATCC 53582 is one of the highest reported bacterial cellulose producing strains and has been used as a model organism in numerous studies of bacterial cellulose production and studies aiming to increased cellulose productivity. Here we present a high-quality draft genome sequence for G. hansenii ATCC 53582 and find that in ...

  14. A new route to produce efficient surface-enhanced Raman spectroscopy substrates: Gold-decorated CdSe nanowires

    KAUST Repository

    Das, Gobind

    2013-04-13

    Surface-enhanced Raman spectroscopy is a popular tool for the detection of extremely small quantities of target molecules. Au nanoparticles have been very successful in this respect due to local enhancement of the light intensity caused by their plasmon resonance. Furthermore, Au nanoparticles are biocompatible, and target substances can be easily attached to their surface. Here, we demonstrate that Au-decorated CdSe nanowires when employed as SERS substrates lead to an enhancement as large as 105 with respect to the flat Au surfaces. In the case of hybrid metal-CdSe nanowires, the Au nucleates preferably on lattice defects at the lateral facets of the nanowires, which leads to a homogeneous distribution of Au nanoparticles on the nanowire, and to an efficient quenching of the nanowire luminescence. Moreover, the size of the Au nanoparticles can be well controlled via the AuCl3 concentration in the fabrication process. We demonstrate the effectiveness of our SERS substrates with two target substances, namely, cresyl-violet and rhodamine-6G. Au-decorated nanowires can be easily fabricated in large quantities at low cost by wet-chemical synthesis. Furthermore, their deposition onto various substrates, as well as the functionalization of these wires with the target substances, is as straightforward as with the traditional markers. © 2013 Springer Science+Business Media Dordrecht.

  15. Effect of Organic Acids on Bacterial Cellulose Produced by Acetobacter xylinum

    Directory of Open Access Journals (Sweden)

    Hongmei Lu

    2016-03-01

    Full Text Available Based on the difference of bacterial cellulose production from rice saccharificate medium and chemical medium under static cultivation, effect of organic acids in the process of bacterial cellulose produced by A. xylinum was studied. The results showed that the kinds and contents of organic acids were different in both culture medium, in which accumulated oxalic acid and tartaric acid inhibited A. xylinum producing BC in chemical medium, while pyruvic acid, malic acid, lactic acid, acetic acid, citric acid and succinic acid, as ethanol, promoted A. xylinum to produce BC. Compared to the blank BC production 1.48 g/L, the optimum addition concentrations of pyruvic acid, malic acid, lactic acid, acetic acid, citric acid, succinic acid, and ethanol in chemical medium were 0.15%, 0.1%, 0.3%, 0.4%, 0.1%, 0.2% , 4% and the BC productions were 2.49 g/L, 2.83 g/L, 2.12 g/L, 2.54 g/L, 2.27 g/L, 1.88 g/L , 2.63 g/L, respectively. The co-existence of above organic acids and ethanol increased BC production even further.

  16. Partial Characteristics of Hydrogen Production by Fermentative Hydrogen-producing Bacterial Strain B49

    Institute of Scientific and Technical Information of China (English)

    Wang Xiangjing(王相晶); Ren Nanqi; Xiang Wensheng; Lin Ming; Guo Wanqian

    2003-01-01

    To investigate the characteristics of hydrogen production by a novel fermentative hydrogen-producing bacterial strain B49 (AF481148 in EMBL), batch experiments are conducted under different conditions. Hydrogen production has a correlation with cell growth and the consumption of glucose and soluble protein. The optimum pH for cell growth is 4.5±0.15. At acidic pH 4.0±0.15, the bacteria has the maximum accumulated hydrogen volume of 2382 ml/L culture and the maximum hydrogen evolution rate of 339.9 ml/L culture*h with 1% glucose. The optimum temperature for cell growth and hydrogen production is 35℃. In addition, fermentative hydrogen-producing bacterial strain B49 can generate hydrogen from the decomposition of other organic substrates such as wheat, soybean, corn, and potato. Moreover, it can also produce hydrogen from molasses wastewater and brewage wastewater, and hydrogen yields are 137.9 ml H2/g COD and 49.9 ml H2/g COD, respectively.

  17. Nutritional and fermentation parameters of Xaraés grass silage produced with bacterial additive

    Directory of Open Access Journals (Sweden)

    Erickson Tiago Pinheiro da Silva

    2014-07-01

    Full Text Available The use of bacterial additives in forage silages with low content of dry matter prevents undesirable fermentation and reduces losses by gases (PG and effluents (PE during the ensiling process. This study aimed to evaluate the fermentation parameters, chemical composition and in vitro digestibility of silage of Urochloa brizantha cv. Xaraés produced with bacterial additive. The inoculant contained the following strains: Propionibacterium acidipropionici + Lactobacillus plantarum; Lactobacillus buchnari; Propionibacterium acipropionici + commercial enzymes and Lactobacillus plantarum and Pediococcus pentosaccus, at 0, 25, 50, 75, 100, and 125% of the recommended level for sugarcane (2 g ton-1. The experiment was a completely randomized design with four replications, and six levels of inoculant (0, 25, 50, 75, 100, and 125%. There was a quadratic relationship between the inoculant addition and the levels of pH, PE, DMIVD, NDF, ADF and LIG of the silage. PG and MM increased linearly with the addition of inoculant. The N-NH3, DM, CP, CEL, HEM and EE were not affected by the inoculant. Bacterial additive at 50% provided increased DMIVD. Appropriate values were found for pH and NH3.

  18. Effects of bacterial action on waste rock producing acid drainage in the Brazilian first uranium mine

    International Nuclear Information System (INIS)

    This work is an evolution of the methodology showed in the paper 'Study of waste of waste rock piles producing acid drainage in the Brazilian first uranium mine', also submitted for INAC2009. Therefore, the present work also related to the determination of chemical species leaching from waste rock pile 4 (WRP4) of the Uranium Mine and Milling Facility located in the Pocos de Caldas Plateau, as well as the generation of acid waters. With the previous experimental setup, it has been observed that not only water and available oxygen are significant to pyrite oxidation reaction, but bacterial activity as well. As a first approach, the present work addresses the same experiment, but now testing without the influence of bacterial action. Therefore, the new methodology and experimental setup is now capable of determining the acidity of water in contact with material from the WRP4 and the concentration of chemical species dissolved as function of time. Such would also show the extent of bacterial action interference on the pyrite oxidation reaction. Results are based on mass balances comparing concentrations of chemical species in the waste rock before the experiment and in the waste rock plus the remaining water after the experiment. In addition, the evolution of the pH and EMF (electromotive force) values along with chemical species quantified through the experiment are presented through graphics. That is followed by discussions on the significance of such results in terms of concentration of the involved chemical species. The present work has also shown the need of improving the injection of air into the system. A more sophisticated experimental setup should be assembled in the near future, which would allow the quantification of differences between experimental tests with and without bacterial action. (author)

  19. Surface modification of polyester to produce a bacterial cellulose-based vascular prosthetic device

    Science.gov (United States)

    Charpentier, Paul A.; Maguire, Anne; Wan, Wan-kei

    2006-07-01

    The surface of medical grade polyesters was modified to impart hydrophilic character for attachment to bacterial synthesized cellulose to produce a vascular prosthetic device. The polyesters were treated with UV/ozone, air plasma, and nitrogen plasma for various lengths of time. The unmodified and modified surfaces were analyzed by X-ray photoelectron spectroscopy (XPS) and advancing contact angle measurements. The surfaces were then coated with bacterial produced cellulose to study adhesion properties through tensile testing (peel testing). UV/ozone and plasma treatment XPS results indicated an increase in the oxygen concentration in the form of C sbnd O(H) on the treated polyester surfaces. The treatment time to reach steady state in the case of air and nitrogen plasmas took the order of seconds, while 7 min and longer were required for UV/ozone treatment. Peel strength tests to measure adhesion of modified polyester to cellulose reached their maximum values when the C sbnd O(H) concentrations were at the highest level. It was also at this level that the contact angle measurements showed no further decrease.

  20. Bacterially produced recombinant influenza vaccines based on virus-like particles.

    Directory of Open Access Journals (Sweden)

    Andrea Jegerlehner

    Full Text Available Although current influenza vaccines are effective in general, there is an urgent need for the development of new technologies to improve vaccine production timelines, capacities and immunogenicity. Herein, we describe the development of an influenza vaccine technology which enables recombinant production of highly efficient influenza vaccines in bacterial expression systems. The globular head domain of influenza hemagglutinin, comprising most of the protein's neutralizing epitopes, was expressed in E. coli and covalently conjugated to bacteriophage-derived virus-like particles produced independently in E.coli. Conjugate influenza vaccines produced this way were used to immunize mice and found to elicit immune sera with high antibody titers specific for the native influenza hemagglutinin protein and high hemagglutination-inhibition titers. Moreover vaccination with these vaccines induced full protection against lethal challenges with homologous and highly drifted influenza strains.

  1. Isolation and identification of bacterial endophytes from pharmaceutical agarwood-producing Aquilaria species

    Directory of Open Access Journals (Sweden)

    Subhash J Bhore

    2013-01-01

    Full Text Available Background: Resins and gums are used in traditional medicine and do have potential applications in pharmacy and medicine. Agarwood is the fragrant resinous wood, which is an important commodity from Aquilaria species and has been used as a sedative, analgesic, and digestive in traditional medicine. Endophytic bacteria are potentially important in producing pharmaceutical compounds found in the plants. Hence, it was important to understand which types of endophytic bacteria are associated with pharmaceutical agarwood-producing Aquilaria species. Objective: This study was undertaken to isolate and identify endophytic bacteria associated with agarwood-producing seven (7 Aquilaria species from Malaysia. Materials and Methods: Botanical samples of seven Aquilaria species were collected, and endophytic bacteria were isolated from surface-sterilized-tissue samples. The 16S rRNA gene fragments were amplified using PCR method, and endophytic bacterial isolates (EBIs were identified based on 16S rRNA gene sequence similarity based method. Results: Culturable, 77 EBIs were analyzed, and results of 16S rRNA gene sequences analysis suggest that 18 different types of endophytic bacteria are associated with (seven Aquilaria species. From 77 EBIs, majority (36.4% of the isolates were of Bacillus pumilus. Conclusion: These findings indicate that agarwood-producing Aquilaria species are harboring 18 different types of culturable endophytic bacteria.

  2. Ability of sea-water bacterial consortium to produce electricity and denitrify water

    Science.gov (United States)

    Maruvada, Nagasamrat V. V.; Tommasi, Tonia; Kaza, Kesava Rao; Ruggeri, Bernardo

    Sea is a store house for varied types of microbes with an ability to reduce and oxidize substances like iron, sulphur, carbon dioxide, etc. Most of these processes happen in the sea water environment, but can be applied for purification of wastewater. In the present paper, we discuss the use of a consortium of seawater bacteria in a fuel cell to produce electricity by oxidizing organic matter and reducing nitrates. We also discuss how the growth of the bacterial consortium can lead to an increased electricity production and decreased diffusional resistance in the cell. The analysis was done using electrochemical impedance spectroscopy (EIS), and linear sweep voltammetry (LSV). Here, we use bicarbonate buffered solution, which is the natural buffering agent found in sea. We show that the seawater bacterial consortium can be used in both the anode and cathode parts of the cell. The results confirm the adaptability of the seawater bacteria to different environments and can be used for various applications. Heritage, Erasmus Mundus Programme, European Commission.

  3. Decreased Bacterial Attachment and Protein Adsorption to Coatings Produced by Low Enegy Plasma Polymerization

    DEFF Research Database (Denmark)

    Andersen, T.E.; Kingshott, Peter; Benter, M.;

    Introduction Silicone rubber is among the most biocompatible materials available, exhibiting low levels of extractables, absence of plasticizers and additives and fairly low activation of blood thrombogenesis components. However untreated silicone rubber does not efficiently resist protein...... with a surface less prone to the adsorption of biological matter. In the current study two different hydrophilic nanoscale coatings were produced by low energy plasma polymerization [3] and investigated· f()rl()w ... pr()tein adsorption and bacterial attachment properties. Methods were setup to enable...... the measurement of both initial adhesion of clinically isolated bacteria on silicone and subsequent biofilm formation during prolonged growth under liquid flow. The extend of adsorption of relevant proteins to the surfaces was also investigated using quartz crystal microbalance with dissipation (QCM...

  4. Screening of bacterial strains for pectinolytic activity: characterization of the polygalacturonase produced by Bacillus sp

    Directory of Open Access Journals (Sweden)

    Soares Márcia M.C.N.

    1999-01-01

    Full Text Available One hundred sixty eight bacterial strains, isolated from soil and samples of vegetable in decomposition, were screened for the use of citrus pectin as the sole carbon source. 102 were positive for pectinase depolymerization in assay plates as evidenced by clear hydrolization halos. Among them, 30% presented considerable pectinolytic activity. The cultivation of these strains by submerged and semi-solid fermentation for polygalacturonase production indicated that five strains of Bacillus sp produced high quantities of the enzyme. The physico-chemical characteristics, such as optimum pH of 6.0 - 7.0, optimum temperatures between 45oC and 55oC, stability at temperatures above 40oC and in neutral and alkaline pH, were determined.

  5. Characterization of Bacterial Mannanase for Hydrolyzing Palm Kernel Cake to Produce Manno-oligosaccharides Prebiotics

    Directory of Open Access Journals (Sweden)

    W. Utami

    2013-12-01

    Full Text Available Palm kernel cake (PKC is a promising source of prebiotics, since it contains high amount of β-mannan which can be further hydrolyzed to manno-oligasaccharides (MOS, a prebiotic. Therefore, this research was carried out to analyze the capability of a bacterial isolate (A2 isolates previously isolated from soils sample from around IPB campus to hydrolyze PKC. Based on 16S-DNA analysis, isolate A2 was identified as Brevibacillus borstelensis. Mannanase of A2 isolate had an optimum condition at 90 oC and pH 7. Mannanase activity of crude extracts using Locust Bean Gum (LBG and PKC as substrates were 0.37U/mL and 0.032U/mL, respectively. However, the most favorable production of oligosaccharides based on the degree of polymerization was obtained after 72-h of incubation with the ratio of substrate:enzyme, 1.2:1, on 1.5% PKC as substrate. The manno-oligosaccharides prebio-tic obtained was found to interfere the growth of both lactic acid bacteria (Lactobacillus casei and pathogenic microflora (Escherichia coli. E. coli apparently could not use this prebiotic as the carbon sources, in contrast to L. casei. Substitution of carbon source in medium with prebiotics reduced the capability of L. casei to produce organic acids. It is concluded that local A2 isolate (B. borstelensis produces mannanase which can be used to produce prebiotics from PKC.

  6. Magnesium improves hydrogen production by a novel fermentative hydrogen-producing bacterial strain B49

    Institute of Scientific and Technical Information of China (English)

    WANG Xiang-jing; REN Nan-qi; XIANG Wen-sheng

    2005-01-01

    Batch experiments were conducted to investigate the effects of magnesium on glucose metabolism, including growth and hydrogen-producing capacity of fermentative hydrogen-producing bacterial strain B49. These abilities were enhanced with an increase in magnesium concentration. At the end of fermentation from 10 g/L ratio of ethanol amount (mg/L) to acetate amount (mg/L) was 1.1, and the accumulated hydrogen volume hydrogen volume was increased to 2 360. 5 mL H2/L culture, the ratio of ethanol amount (mg/L) to acetate amount (mg/L) was increased to 1.3 and polysaccharide was decreased to 2. 5 mg/L. Moreover, the magnesium solution addition to the medium at different fermentation times affected hydrogen-producing ability. However,the later the addition time was postponed, the less the effect was on hydrogen evolution. Further experiments confirmed the enhancement was dependent on magnesium ions and not on the other inorganic ions such as SO42- or Cl-, which constituted the magnesium salts.

  7. Bacterial endophyte Sphingomonas sp. LK11 produces gibberellins and IAA and promotes tomato plant growth.

    Science.gov (United States)

    Khan, Abdul Latif; Waqas, Muhammad; Kang, Sang-Mo; Al-Harrasi, Ahmed; Hussain, Javid; Al-Rawahi, Ahmed; Al-Khiziri, Salima; Ullah, Ihsan; Ali, Liaqat; Jung, Hee-Young; Lee, In-Jung

    2014-08-01

    Plant growth promoting endophytic bacteria have been identified as potential growth regulators of crops. Endophytic bacterium, Sphingomonas sp. LK11, was isolated from the leaves of Tephrosia apollinea. The pure culture of Sphingomonas sp. LK11 was subjected to advance chromatographic and spectroscopic techniques to extract and isolate gibberellins (GAs). Deuterated standards of [17, 17-(2)H2]-GA4, [17, 17-(2)H2]-GA9 and [17, 17-(2)H2]-GA20 were used to quantify the bacterial GAs. The analysis of the culture broth of Sphingomonas sp. LK11 revealed the existence of physiologically active gibberellins (GA4: 2.97 ± 0.11 ng/ml) and inactive GA9 (0.98 ± 0.15 ng/ml) and GA20 (2.41 ± 0.23). The endophyte also produced indole acetic acid (11.23 ± 0.93 μM/ml). Tomato plants inoculated with endophytic Sphingomonas sp. LK11 showed significantly increased growth attributes (shoot length, chlorophyll contents, shoot, and root dry weights) compared to the control. This indicated that such phyto-hormones-producing strains could help in increasing crop growth. PMID:24994010

  8. Textile Dye Removal from Wastewater Effluents Using Bioflocculants Produced by Indigenous Bacterial Isolates

    Directory of Open Access Journals (Sweden)

    Balakrishna Pillay

    2012-11-01

    Full Text Available Bioflocculant-producing bacteria were isolated from activated sludge of a wastewater treatment plant located in Durban, South Africa, and identified using standard biochemical tests as well as the analysis of their 16S rRNA gene sequences. The bioflocculants produced by these organisms were ethanol precipitated, purified using 2% (w/v cetylpyridinium chloride solution and evaluated for removal of wastewater dyes under different pH, temperature and nutritional conditions. Bioflocculants from these indigenous bacteria were very effective for decolourizing the different dyes tested in this study, with a removal rate of up to 97.04%. The decolourization efficiency was largely influenced by the type of dye, pH, temperature, and flocculant concentration. A pH of 7 was found to be optimum for the removal of both whale and mediblue dyes, while the optimum pH for fawn and mixed dye removal was found to be between 9 and 10. Optimum temperature for whale and mediblue dye removal was 35 °C, and that for fawn and mixed dye varied between 40–45 °C and 35–40 °C, respectively. These bacterial bioflocculants may provide an economical and cleaner alternative to replace or supplement present treatment processes for the removal of dyes from wastewater effluents, since they are biodegradable and easily sustainable.

  9. Antimicrobial Activity of Monoramnholipids Produced by Bacterial Strains Isolated from the Ross Sea (Antarctica).

    Science.gov (United States)

    Tedesco, Pietro; Maida, Isabel; Palma Esposito, Fortunato; Tortorella, Emiliana; Subko, Karolina; Ezeofor, Chidinma Christiana; Zhang, Ying; Tabudravu, Jioji; Jaspars, Marcel; Fani, Renato; de Pascale, Donatella

    2016-05-01

    Microorganisms living in extreme environments represent a huge reservoir of novel antimicrobial compounds and possibly of novel chemical families. Antarctica is one of the most extraordinary places on Earth and exhibits many distinctive features. Antarctic microorganisms are well known producers of valuable secondary metabolites. Specifically, several Antarctic strains have been reported to inhibit opportunistic human pathogens strains belonging to Burkholderia cepacia complex (Bcc). Herein, we applied a biodiscovery pipeline for the identification of anti-Bcc compounds. Antarctic sub-sea sediments were collected from the Ross Sea, and used to isolate 25 microorganisms, which were phylogenetically affiliated to three bacterial genera (Psychrobacter, Arthrobacter, and Pseudomonas) via sequencing and analysis of 16S rRNA genes. They were then subjected to a primary cell-based screening to determine their bioactivity against Bcc strains. Positive isolates were used to produce crude extracts from microbial spent culture media, to perform the secondary screening. Strain Pseudomonas BNT1 was then selected for bioassay-guided purification employing SPE and HPLC. Finally, LC-MS and NMR structurally resolved the purified bioactive compounds. With this strategy, we achieved the isolation of three rhamnolipids, two of which were new, endowed with high (MIC < 1 μg/mL) and unreported antimicrobial activity against Bcc strains. PMID:27128927

  10. Antimicrobial Activity of Monoramnholipids Produced by Bacterial Strains Isolated from the Ross Sea (Antarctica) †

    Science.gov (United States)

    Tedesco, Pietro; Maida, Isabel; Palma Esposito, Fortunato; Tortorella, Emiliana; Subko, Karolina; Ezeofor, Chidinma Christiana; Zhang, Ying; Tabudravu, Jioji; Jaspars, Marcel; Fani, Renato; de Pascale, Donatella

    2016-01-01

    Microorganisms living in extreme environments represent a huge reservoir of novel antimicrobial compounds and possibly of novel chemical families. Antarctica is one of the most extraordinary places on Earth and exhibits many distinctive features. Antarctic microorganisms are well known producers of valuable secondary metabolites. Specifically, several Antarctic strains have been reported to inhibit opportunistic human pathogens strains belonging to Burkholderia cepacia complex (Bcc). Herein, we applied a biodiscovery pipeline for the identification of anti-Bcc compounds. Antarctic sub-sea sediments were collected from the Ross Sea, and used to isolate 25 microorganisms, which were phylogenetically affiliated to three bacterial genera (Psychrobacter, Arthrobacter, and Pseudomonas) via sequencing and analysis of 16S rRNA genes. They were then subjected to a primary cell-based screening to determine their bioactivity against Bcc strains. Positive isolates were used to produce crude extracts from microbial spent culture media, to perform the secondary screening. Strain Pseudomonas BNT1 was then selected for bioassay-guided purification employing SPE and HPLC. Finally, LC-MS and NMR structurally resolved the purified bioactive compounds. With this strategy, we achieved the isolation of three rhamnolipids, two of which were new, endowed with high (MIC < 1 μg/mL) and unreported antimicrobial activity against Bcc strains. PMID:27128927

  11. H2-producing bacterial communities from a heat-treated soil inoculum.

    Science.gov (United States)

    Iyer, Prabha; Bruns, Mary Ann; Zhang, Husen; Van Ginkel, Steve; Logan, Bruce E

    2004-12-01

    Hydrogen gas (approximately 60% H(2)) was produced in a continuous flow bioreactor inoculated with heat-treated soil, and fed synthetic wastewater containing glucose (9.5 g l(-1)). The pH in the bioreactor was maintained at 5.5 to inhibit consumption of H(2) by methanogens. The objective of this study was to characterize bacterial communities in the reactor operated under two different hydraulic retention times (HRTs of 30-h and 10-h) and temperatures (30 degrees C and 37 degrees C). At 30-h HRT, the H(2) production rate was 80 ml h(-1) and yield was 0.91 mol H(2)/mol glucose. At 10-h HRT, the H(2) production rate was more than 5 times higher at 436 ml h(-1), and yield was 1.61 mol H(2)/mol glucose. Samples were removed from the reactor under steady-state conditions for PCR-based detection of bacterial populations by ribosomal intergenic spacer analysis (RISA). Populations detected at 30-h HRT were more diverse than at 10-h HRT and included representatives of Bacillaceae, Clostridiaceae, and Enterobacteriaceae. At 10-h HRT, only Clostridiaceae were detected. When the temperature of the 10-h HRT reactor was increased from 30 degrees C to 37 degrees C, the steady-state H(2) production rate increased slightly to 463 ml h(-1) and yield was 1.8 mol H(2)/mol glucose. Compared to 30 degrees C, RISA fingerprints at 37 degrees C from the 10-h HRT bioreactor exhibited a clear shift from populations related to Clostridium acidisoli (subcluster Ic) to populations related to Clostridium acetobutylicum (subcluster Ib). PMID:15558274

  12. Bacterial diversity and composition in major fresh produce growing soils affected by physiochemical properties and geographic locations.

    Science.gov (United States)

    Ma, Jincai; Ibekwe, A Mark; Yang, Ching-Hong; Crowley, David E

    2016-09-01

    Microbial diversity of agricultural soils has been well documented, but information on leafy green producing soils is limited. In this study, we investigated microbial diversity and community structures in 32 (16 organic, 16 conventionally managed soils) from California (CA) and Arizona (AZ) using pyrosequencing, and identified factors affecting bacterial composition. Results of detrended correspondence analysis (DCA) and dissimilarity analysis showed that bacterial community structures of conventionally managed soils were similar to that of organically managed soils; while the bacterial community structures in soils from Salinas, California were different (Psoils from Yuma, Arizona and Imperial Valley, California. Canonical correspondence analysis (CCA) and artificial neural network (ANN) analysis of bacterial community structures and soil variables showed that electrical conductivity (EC), clay content, water-holding capacity (WHC), pH, total nitrogen (TN), and organic carbon (OC) significantly (Psoil physical properties (clay, EC, and WHC), soil chemical variables (pH, TN, and OC) and sampling location explained 16.3%, 12.5%, and 50.9%, respectively, of total variations in bacterial community structure, leaving 13% of the total variation unexplained. Our current study showed that bacterial community composition and diversity in major fresh produce growing soils from California and Arizona is a function of soil physiochemical characteristics and geographic distances of sampling sites. PMID:27135583

  13. Complete Genome Sequence of Gluconacetobacter hansenii Strain NQ5 (ATCC 53582), an Efficient Producer of Bacterial Cellulose.

    Science.gov (United States)

    Pfeffer, Sarah; Mehta, Kalpa; Brown, R Malcolm

    2016-01-01

    This study reports the release of the complete nucleotide sequence of Gluconacetobacter hansenii strain NQ5 (ATCC 53582). This strain was isolated by R. Malcolm Brown, Jr. in a sugar mill in North Queensland, Australia, and is an efficient producer of bacterial cellulose. The elucidation of the genome will contribute to the study of the molecular mechanisms necessary for cellulose biosynthesis. PMID:27516505

  14. Electrically conductive bacterial cellulose composite membranes produced by the incorporation of graphite nanoplatelets in pristine bacterial cellulose membranes

    Directory of Open Access Journals (Sweden)

    T. Zhou

    2013-09-01

    Full Text Available Graphite nanoplatelets (GNPs were utilized to improve the electrical conductivity of pristine bacterial cellulose (BC membranes. By physical and chemical methods, flake-shaped GNPs, weaving through the surface layer of web-like cellulose nanofibrils, were indeed fixed or trapped by the adjacent nanofibrils in the BC surface network, for comparison, rod-shaped multi-walled carbon nanotubes (MWCNTs were homogeneously inserted into BC membrane through the pore structures and tunnels within the BC membrane. Strong physical and chemical interaction exists between the BC nanofibrils and the particles of GNP or MWCNT even after 15 h sonication. BC membrane with 8.7 wt% incorporated GNPs reached the maximum electrical conductivity of 4.5 S/cm, while 13.9 wt% MWCNT/BC composite membrane achieved the maximum electrical conductivity of 1.2 S/cm. Compared with one dimensional (1-D MWCNTs, as long as GNPs inserted into BC membranes, the 2-D reinforcement of GNPs was proven to be more effective in improving the electrical conductivity of BC membranes thus not only break the bottleneck of further improvement of the electrical conductivity of BC-based composite membranes but also broaden the applications of BC and GNPs.

  15. Bacterial Inhibition and Antioxidant Activity of Kefir Produced from Thai Jasmine Rice Milk

    OpenAIRE

    Deeseenthum Sirirat; Pejovic Jelena

    2010-01-01

    The aim of this study was to investigate the bacterial inhibition and antioxidant activity of 24 and 48 h of rice milk-kefir and cow milk-kefir. Bacterial inhibition activity of kefir was investigated against Staphylococcus aureus, Bacillus subtillis, Escherichia coli and Pseudomonas fluorescens by using the disk diffusion method. Kefir showed some activity against all organisms tested. Antioxidant activity of kefir was measured using three different methods: DPPH radical scavenging activity ...

  16. Engineering control of bacterial cellulose production using a genetic toolkit and a new cellulose-producing strain

    Science.gov (United States)

    Florea, Michael; Hagemann, Henrik; Santosa, Gabriella; Micklem, Chris N.; Spencer-Milnes, Xenia; de Arroyo Garcia, Laura; Paschou, Despoina; Lazenbatt, Christopher; Kong, Deze; Chughtai, Haroon; Jensen, Kirsten; Freemont, Paul S.; Kitney, Richard; Reeve, Benjamin; Ellis, Tom

    2016-01-01

    Bacterial cellulose is a strong and ultrapure form of cellulose produced naturally by several species of the Acetobacteraceae. Its high strength, purity, and biocompatibility make it of great interest to materials science; however, precise control of its biosynthesis has remained a challenge for biotechnology. Here we isolate a strain of Komagataeibacter rhaeticus (K. rhaeticus iGEM) that can produce cellulose at high yields, grow in low-nitrogen conditions, and is highly resistant to toxic chemicals. We achieved external control over its bacterial cellulose production through development of a modular genetic toolkit that enables rational reprogramming of the cell. To further its use as an organism for biotechnology, we sequenced its genome and demonstrate genetic circuits that enable functionalization and patterning of heterologous gene expression within the cellulose matrix. This work lays the foundations for using genetic engineering to produce cellulose-based materials, with numerous applications in basic science, materials engineering, and biotechnology. PMID:27247386

  17. Engineering control of bacterial cellulose production using a genetic toolkit and a new cellulose-producing strain.

    Science.gov (United States)

    Florea, Michael; Hagemann, Henrik; Santosa, Gabriella; Abbott, James; Micklem, Chris N; Spencer-Milnes, Xenia; de Arroyo Garcia, Laura; Paschou, Despoina; Lazenbatt, Christopher; Kong, Deze; Chughtai, Haroon; Jensen, Kirsten; Freemont, Paul S; Kitney, Richard; Reeve, Benjamin; Ellis, Tom

    2016-06-14

    Bacterial cellulose is a strong and ultrapure form of cellulose produced naturally by several species of the Acetobacteraceae Its high strength, purity, and biocompatibility make it of great interest to materials science; however, precise control of its biosynthesis has remained a challenge for biotechnology. Here we isolate a strain of Komagataeibacter rhaeticus (K. rhaeticus iGEM) that can produce cellulose at high yields, grow in low-nitrogen conditions, and is highly resistant to toxic chemicals. We achieved external control over its bacterial cellulose production through development of a modular genetic toolkit that enables rational reprogramming of the cell. To further its use as an organism for biotechnology, we sequenced its genome and demonstrate genetic circuits that enable functionalization and patterning of heterologous gene expression within the cellulose matrix. This work lays the foundations for using genetic engineering to produce cellulose-based materials, with numerous applications in basic science, materials engineering, and biotechnology. PMID:27247386

  18. Genome sequence and plasmid transformation of the model high-yield bacterial cellulose producer Gluconacetobacter hansenii ATCC 53582

    Science.gov (United States)

    Florea, Michael; Reeve, Benjamin; Abbott, James; Freemont, Paul S.; Ellis, Tom

    2016-03-01

    Bacterial cellulose is a strong, highly pure form of cellulose that is used in a range of applications in industry, consumer goods and medicine. Gluconacetobacter hansenii ATCC 53582 is one of the highest reported bacterial cellulose producing strains and has been used as a model organism in numerous studies of bacterial cellulose production and studies aiming to increased cellulose productivity. Here we present a high-quality draft genome sequence for G. hansenii ATCC 53582 and find that in addition to the previously described cellulose synthase operon, ATCC 53582 contains two additional cellulose synthase operons and several previously undescribed genes associated with cellulose production. In parallel, we also develop optimized protocols and identify plasmid backbones suitable for transformation of ATCC 53582, albeit with low efficiencies. Together, these results provide important information for further studies into cellulose synthesis and for future studies aiming to genetically engineer G. hansenii ATCC 53582 for increased cellulose productivity.

  19. Organic Nanowires

    DEFF Research Database (Denmark)

    Balzer, Frank; Schiek, Manuela; Al-Shamery, Katharina;

    Single crystalline nanowires from fluorescing organic molecules like para-phenylenes or thiophenes are supposed to become key elements in future integrated optoelectronic devices [1]. For a sophisticated design of devices based on nanowires the basic principles of the nanowire formation have to be...

  20. TRPA1 channels mediate acute neurogenic inflammation and pain produced by bacterial endotoxins

    Science.gov (United States)

    Meseguer, Victor; Alpizar, Yeranddy A.; Luis, Enoch; Tajada, Sendoa; Denlinger, Bristol; Fajardo, Otto; Manenschijn, Jan-Albert; Fernández-Peña, Carlos; Talavera, Arturo; Kichko, Tatiana; Navia, Belén; Sánchez, Alicia; Señarís, Rosa; Reeh, Peter; Pérez-García, María Teresa; López-López, José Ramón; Voets, Thomas; Belmonte, Carlos; Talavera, Karel; Viana, Félix

    2014-01-01

    Gram-negative bacterial infections are accompanied by inflammation and somatic or visceral pain. These symptoms are generally attributed to sensitization of nociceptors by inflammatory mediators released by immune cells. Nociceptor sensitization during inflammation occurs through activation of the Toll-like receptor 4 (TLR4) signalling pathway by lipopolysaccharide (LPS), a toxic by-product of bacterial lysis. Here we show that LPS exerts fast, membrane delimited, excitatory actions via TRPA1, a transient receptor potential cation channel that is critical for transducing environmental irritant stimuli into nociceptor activity. Moreover, we find that pain and acute vascular reactions, including neurogenic inflammation (CGRP release) caused by LPS are primarily dependent on TRPA1 channel activation in nociceptive sensory neurons, and develop independently of TLR4 activation. The identification of TRPA1 as a molecular determinant of direct LPS effects on nociceptors offers new insights into the pathogenesis of pain and neurovascular responses during bacterial infections and opens novel avenues for their treatment.

  1. The Population Structure of Antibiotic-Producing Bacterial Symbionts of Apterostigma dentigerum Ants: Impacts of Coevolution and Multipartite Symbiosis

    OpenAIRE

    Caldera, Eric J.; Currie, Cameron R

    2012-01-01

    Fungus-growing ants (Attini) are part of a complex symbiosis with Basidiomycetous fungi, which the ants cultivate for food, Ascomycetous fungal pathogens (Escovopsis), which parasitize cultivars, and Actinobacteria, which produce antibiotic compounds that suppress pathogen growth. Earlier studies that have characterized the association between attine ants and their bacterial symbionts have employed broad phylogenetic approaches, with conclusions ranging from a diffuse coevolved mutualism to n...

  2. Characterization of Geographically Distinct Bacterial Communities Associated with Coral Mucus Produced by Acropora spp. and Porites spp.

    OpenAIRE

    McKew, B.A.; Dumbrell, A.J.; Daud, S. D.; Hepburn, L; Thorpe, E.; Mogensen, L.; Whitby, C.

    2012-01-01

    Acropora and Porites corals are important reef builders in the Indo-Pacific and Caribbean. Bacteria associated with mucus produced by Porites spp. and Acropora spp. from Caribbean (Punta Maroma, Mexico) and Indo-Pacific (Hoga and Sampela, Indonesia) reefs were determined. Analysis of pyrosequencing libraries showed that bacterial communities from Caribbean corals were significantly more diverse (H′, 3.18 to 4.25) than their Indonesian counterparts (H′, 2.54 to 3.25). Dominant taxa were Gammap...

  3. Exploration and conservation of bacterial genetic resources as bacteriocin producing inhibitory microorganisms to pathogen bacteria in livestock

    OpenAIRE

    2013-01-01

    Exploration and conservation of microorganisms producing bacteriocin was done as the primary study towards the collection of potential bacteria and its application in improving livestock health condition and inhibit food borne pathogens. Diferent kinds of samples such as beef cattle rectal swab, rumen fluids, cow’s milk, chicken gut content, goat’s milk were collected at Bogor cattle slaughter houses, poultry slaughter houses, dairy cattle and goat farms. A total of 452 bacterial isolates con...

  4. Effects of Interactions of Auxin-Producing Bacteria and Bacterial-Feeding Nematodes on Regulation of Peanut Growths

    OpenAIRE

    Li Xu; Wensi Xu; Ying Jiang; Feng Hu; Huixin Li

    2015-01-01

    The influences of an IAA (indole-3-acetic acid)-producing bacterium (Bacillus megaterium) and two bacterial-feeding nematodes (Cephalobus sp. or Mesorhabditis sp.) on the growth of peanut (Arachis hypogaea L. cv. Haihua 1) after various durations of time were investigated in natural soils. The addition of bacteria and nematodes and incubation time all significantly affected plant growth, plant root growth, plant nutrient concentrations, soil nutrient concentrations, soil microorganisms and so...

  5. Identification of a New Marine Bacterial Strain SD8 and Optimization of Its Culture Conditions for Producing Alkaline Protease

    OpenAIRE

    Hongxia Cui; Muyang Yang; Liping Wang; Xian, Cory J.

    2015-01-01

    While much attention has been given to marine microorganisms for production of enzymes, which in general are relatively more stable and active compared to those from plants and animals, studies on alkaline protease production from marine microorganisms have been very limited. In the present study, the alkaline protease producing marine bacterial strain SD8 isolated from sea muds in the Geziwo Qinhuangdao sea area of China was characterized and its optimal culture conditions were investigated....

  6. Alkylpyrazines produced by bacterial spoilage of heat-treated and gamma-irradiated coconut

    International Nuclear Information System (INIS)

    This paper reports the sterilisation of coconut by autoclaving or gamma irradiation, followed by storage in water at 250 C for 8 weeks. Bacillus subtilis developed after storage in water. The volatile compounds formed as a result of bacterial activity were extracted and identified. (U.K.)

  7. Effects of Iron on Hydrogen-producing Capacity,Hydrogenase and NADH-fd Reductase Activities of a Fermentative Hydrogen-producing Bacterial Strain B49

    Institute of Scientific and Technical Information of China (English)

    Wang Xiangjing(王相晶); Ren Nanqi; Xiang Wensheng

    2004-01-01

    Iron plays an important role in hydrogen production, cell growth, hydrogenase and NADH-fd reductase activities of hydrogen-producing bacterial strain B49 (AF481148 in EMBL). At the end of fermentation from 10 g/L glucose, for the culture containing 10 mg/L FeSO4*7H2O the cell growth in terms of optical density (OD) at 600nm was 1.13, the ratio of ethanol amount (mg/L) to acetate amount (mg/L) was 1.55, and the accumulated hydrogen volume was 1816.3 ml H2/L culture; whereas for the culture of 80 mg/L FeSO4*7H2O OD600nm was increased to 1.34, the accumulated hydrogen volume was increased to 2360.5 ml H2/L culture, and the ratio of ethanol amount (mg/L) to acetate amount (mg/L) decreased to 1.31. Moreover, the iron addition to the medium at different fermentation time could affect hydrogen-producing ability. However, the later the addition time of FeSO4*7H2O was postponed, the less the effect on hydrogen evolution was. In the course of fermentation, the specific activities of hydrogenase and NADH-fd reductase of hydrogen-producing bacterial strain B49 decreased with the consumption of iron.

  8. No evidence for a culturable bacterial tetrodotoxin producer in Pleurobranchaea maculata (Gastropoda: Pleurobranchidae) and Stylochoplana sp. (Platyhelminthes: Polycladida).

    Science.gov (United States)

    Salvitti, Lauren R; Wood, Susanna A; McNabb, Paul; Cary, Stephen Craig

    2015-02-01

    Tetrodotoxin (TTX) is a potent neurotoxin found in the tissues of many taxonomically diverse organisms. Its origin has been the topic of much debate, with suggestions including endogenous production, acquisition through diet, and symbiotic bacterial synthesis. Bacterial production of TTX has been reported in isolates from marine biota, but at lower than expected concentrations. In this study, 102 strains were isolated from Pleurobranchaea maculata (Opisthobranchia) and Stylochoplana sp. (Platyhelminthes). Tetrodotoxin production was tested utilizing a recently developed sensitive method to detect the C9 base of TTX via liquid chromatography-mass spectrometry. Bacterial strains were characterized by sequencing a region of the 16S ribosomal RNA gene. To account for the possibility that TTX is produced by a consortium of bacteria, a series of experiments using marine broth spiked with various P. maculata tissues were undertaken. Sixteen unique strains from P. maculata and one from Stylochoplana sp. were isolated, representing eight different genera; Pseudomonadales, Actinomycetales, Oceanospirillales, Thiotrichales, Rhodobacterales, Sphingomonadales, Bacillales, and Vibrionales. Molecular fingerprinting of bacterial communities from broth experiments showed little change over the first four days. No C9 base or TTX was detected in isolates or broth experiments (past day 0), suggesting a culturable microbial source of TTX in P. maculata and Stylochoplana sp. is unlikely. PMID:25635464

  9. No Evidence for a Culturable Bacterial Tetrodotoxin Producer in Pleurobranchaea maculata (Gastropoda: Pleurobranchidae and Stylochoplana sp. (Platyhelminthes: Polycladida

    Directory of Open Access Journals (Sweden)

    Lauren R. Salvitti

    2015-01-01

    Full Text Available Tetrodotoxin (TTX is a potent neurotoxin found in the tissues of many taxonomically diverse organisms. Its origin has been the topic of much debate, with suggestions including endogenous production, acquisition through diet, and symbiotic bacterial synthesis. Bacterial production of TTX has been reported in isolates from marine biota, but at lower than expected concentrations. In this study, 102 strains were isolated from Pleurobranchaea maculata (Opisthobranchia and Stylochoplana sp. (Platyhelminthes. Tetrodotoxin production was tested utilizing a recently developed sensitive method to detect the C9 base of TTX via liquid chromatography—mass spectrometry. Bacterial strains were characterized by sequencing a region of the 16S ribosomal RNA gene. To account for the possibility that TTX is produced by a consortium of bacteria, a series of experiments using marine broth spiked with various P. maculata tissues were undertaken. Sixteen unique strains from P. maculata and one from Stylochoplana sp. were isolated, representing eight different genera; Pseudomonadales, Actinomycetales, Oceanospirillales, Thiotrichales, Rhodobacterales, Sphingomonadales, Bacillales, and Vibrionales. Molecular fingerprinting of bacterial communities from broth experiments showed little change over the first four days. No C9 base or TTX was detected in isolates or broth experiments (past day 0, suggesting a culturable microbial source of TTX in P. maculata and Stylochoplana sp. is unlikely.

  10. Biodegradation of Leonardite by an alkali-producing bacterial community and characterization of the degraded products.

    Science.gov (United States)

    Gao, Tong-Guo; Jiang, Feng; Yang, Jin-Shui; Li, Bao-Zhen; Yuan, Hong-Li

    2012-03-01

    In this study, three bacterial communities were obtained from 12 Leonardite samples with the aim of identifying a clean, effective, and economic technique for the dissolution of Leonardite, a type of low-grade coal, in the production of humic acid (HA). The biodegradation ability and characteristics of the degraded products of the most effective bacterial community (MCSL-2), which degraded 50% of the Leonardite within 21 days, were further investigated. Analyses of elemental composition, (13)C NMR, and Fourier transform infrared revealed that the contents of C, O, and aliphatic carbon were similar in biodegraded humic acid (bHA) and chemically (alkali) extracted humic acid (cHA). However, the N and carboxyl carbon contents of bHA was higher than that of cHA. Furthermore, a positive correlation was identified between the degradation efficiency and the increasing pH of the culture medium, while increases of manganese peroxidase and esterase activities were also observed. These data demonstrated that both alkali production and enzyme reactions were involved in Leonardite solubilization by MCSL-2, although the former mechanism predominated. No fungus was observed by microscopy. Only four bacterial phylotypes were recognized, and Bacillus licheniformis-related bacteria were identified as the main group in MCSL-2 by analysis of amplified 16S rRNA genes, thus demonstrating that Leonardite degradation ability has a limited distribution in bacteria. Hormone-like bioactivities of bHA were also detected. In this study, a bacterial community capable of Leonardite degradation was identified and the products characterized. These data implicate the use of such bacteria for the exploitation of Leonardite as a biofertilizer. PMID:22075634

  11. Resistance to ketolide antibiotics by coordinated expression of rRNA methyltransferases in a bacterial producer of natural ketolides

    DEFF Research Database (Denmark)

    Almutairi, Mashal M; Park, Sung Ryeol; Rose, Simon;

    2015-01-01

    Ketolides are promising new antimicrobials effective against a broad range of Gram-positive pathogens, in part because of the low propensity of these drugs to trigger the expression of resistance genes. A natural ketolide pikromycin and a related compound methymycin are produced by Streptomyces...... activation by ketolide antibiotics. The resistance genes and the induction mechanism remain fully functional when transferred to heterologous bacterial hosts. The anticipated wide use of ketolide antibiotics could promote horizontal transfer of these highly efficient resistance genes to pathogens. Taken...... together, these findings emphasized the need for surveillance of pikR1/pikR2-based bacterial resistance and the preemptive development of drugs that can remain effective against the ketolide-specific resistance mechanism....

  12. Methods for synthesizing metal oxide nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Sunkara, Mahendra Kumar; Kumar, Vivekanand; Kim, Jeong H.; Clark, Ezra Lee

    2016-08-09

    A method of synthesizing a metal oxide nanowire includes the steps of: combining an amount of a transition metal or a transition metal oxide with an amount of an alkali metal compound to produce a mixture; activating a plasma discharge reactor to create a plasma discharge; exposing the mixture to the plasma discharge for a first predetermined time period such that transition metal oxide nanowires are formed; contacting the transition metal oxide nanowires with an acid solution such that an alkali metal ion is exchanged for a hydrogen ion on each of the transition metal oxide nanowires; and exposing the transition metal oxide nanowires to the plasma discharge for a second predetermined time period to thermally anneal the transition metal oxide nanowires. Transition metal oxide nanowires produced using the synthesis methods described herein are also provided.

  13. Zoosporic plant pathogens produce bacterial autoinducer-2 that affects Vibrio harveyi quorum sensing

    Science.gov (United States)

    Kong, Ping; Lee, Bobby W.K.; Zhou, Zhaohui Sunny; Hong, Chuanxue

    2009-01-01

    The frequent co-isolation of bacteria with Phytophthora and Pythium species suggests possible interspecies communication. Zoospore free fluids (ZFF) from bacteria-free and nutrient-depleted zoospore suspensions were examined to investigate production of autoinducer-2 (AI-2), a bacterial interspecies signal molecule, by zoosporic oomycetes. ZFF from P. nicotianae, P. sojae and Py. aphanidermatum triggered luminescence of Vibrio harveyi AI-2 reporter, indicating the presence of AI-2 in zoospore extracellular products and the potential of cross-kingdom communication between oomycetes and bacteria. Production of AI-2 by zoospores was confirmed by chemical assays. These results provide new insight into the physiology and ecology of oomycetes. PMID:20002192

  14. Preclinical test: bacterial reverse mutation test for {sup 18}F-fluorocholine produced in CDTN

    Energy Technology Data Exchange (ETDEWEB)

    Mendes, Bruno M.; Bispo, Ana Carolina A.; Campos, Danielle C.; Silva, Juliana B., E-mail: bmm@cdtn.br, E-mail: acab@cdtn.br, E-mail: dcc@cdtn.br, E-mail: silvajb@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2013-07-01

    The choline labeled with fluorine-18 (18FCH) is being considered as a great importance radiopharmaceutical due to its effective detection of many type of malignant neoplasm. The research related to {sup 18}F-fluorocholine synthesis in CDTN was initiated in 2010. In order to obtain clinical research approval, as well as to register {sup 18}FCH for marketing, safety and efficacy preclinical testing are required. The present work evaluated the {sup 18}FCH genotoxic potential through the bacterial reverse mutation test (Ames test) using Salmonella typhimurium TA-98, TA-100, TA-1535 and TA-1537 strains and Escherichia coli WP2 uvrA strain. The reverse mutation test in bacteria for fluorcolina was conducted in two stages. Initially the method was applied to 'cold' fluorocholine molecule (19FCH). Subsequently, the decayed product of {sup 18}FCH synthesis was evaluated. The first step was performed in order to examine the FCH molecule mutagenicity. The second was carried out to determine the mutagenic potential of final product. All strains were tested in triplicate for each exposure concentration, in the presence and absence of metabolic activation (S-9 mix - 10%). There were no statistically significant increases in revertant colonies rate for any strains tested after their exposure to decayed {sup 18}FCH or {sup 19}FCH. The number of revertant colonies in positive controls was significantly higher than that observed in significant increases in revertant colonies rate for any strains tested after their exposure to decayed {sup 18}FCH or {sup 19}FCH. The number of revertant colonies in positive controls was significantly higher than that observed in negative controls. Based on results of this assay, {sup 18}FCH and {sup 19}FCH, at tested doses, were found to be non-mutagenic in bacterial reverse mutation test. (author)

  15. Preclinical test: bacterial reverse mutation test for 18F-fluorocholine produced in CDTN

    International Nuclear Information System (INIS)

    The choline labeled with fluorine-18 (18FCH) is being considered as a great importance radiopharmaceutical due to its effective detection of many type of malignant neoplasm. The research related to 18F-fluorocholine synthesis in CDTN was initiated in 2010. In order to obtain clinical research approval, as well as to register 18FCH for marketing, safety and efficacy preclinical testing are required. The present work evaluated the 18FCH genotoxic potential through the bacterial reverse mutation test (Ames test) using Salmonella typhimurium TA-98, TA-100, TA-1535 and TA-1537 strains and Escherichia coli WP2 uvrA strain. The reverse mutation test in bacteria for fluorcolina was conducted in two stages. Initially the method was applied to 'cold' fluorocholine molecule (19FCH). Subsequently, the decayed product of 18FCH synthesis was evaluated. The first step was performed in order to examine the FCH molecule mutagenicity. The second was carried out to determine the mutagenic potential of final product. All strains were tested in triplicate for each exposure concentration, in the presence and absence of metabolic activation (S-9 mix - 10%). There were no statistically significant increases in revertant colonies rate for any strains tested after their exposure to decayed 18FCH or 19FCH. The number of revertant colonies in positive controls was significantly higher than that observed in significant increases in revertant colonies rate for any strains tested after their exposure to decayed 18FCH or 19FCH. The number of revertant colonies in positive controls was significantly higher than that observed in negative controls. Based on results of this assay, 18FCH and 19FCH, at tested doses, were found to be non-mutagenic in bacterial reverse mutation test. (author)

  16. Textile Dye Removal from Wastewater Effluents Using Bioflocculants Produced by Indigenous Bacterial Isolates

    OpenAIRE

    Balakrishna Pillay; Ademola O Olaniran; Simphiwe P. Buthelezi

    2012-01-01

    Bioflocculant-producing bacteria were isolated from activated sludge of a wastewater treatment plant located in Durban, South Africa, and identified using standard biochemical tests as well as the analysis of their 16S rRNA gene sequences. The bioflocculants produced by these organisms were ethanol precipitated, purified using 2% (w/v) cetylpyridinium chloride solution and evaluated for removal of wastewater dyes under different pH, temperature and nutritional conditions. Bioflocculants from ...

  17. Isolation and characterization of rhamnolipid-producing bacterial strains from a biodiesel facility.

    Science.gov (United States)

    Rooney, Alejandro P; Price, Neil P J; Ray, Karen J; Kuo, Tsung-Min

    2009-06-01

    Novel strains of rhamnolipid-producing bacteria were isolated from soils at a biodiesel facility on the basis of their ability to grow on glycerol as a sole carbon source. Strains were identified as Acinetobacter calcoaceticus, Enterobacter asburiae, Enterobacter hormaechei, Pantoea stewartii, and Pseudomonas aeruginosa. The strains of the former five species were found to produce rhamnolipids in quantities the same as, or similar to, coisolated strains of P. aeruginosa. Measurements of surface tension revealed that that emulsifying properties of these strains were similar to levels displayed by rhamnolipids produced by P. aeruginosa. Results of matrix-assisted laser desorption/ionization time-of-flight MS analyses revealed that the predominant compounds made by all strains were C10-C10 mono- and dirhamnolipids. Notably, E. hormaechei and one strain of A. calcoaceticus produced rhamnolipids in amounts similar to the pseudomonads. As all strains examined were from the same taxonomic class of Proteobacteria, further examination of this group may reveal many additional species not previously known to produce rhamnolipids in addition to novel strains of species currently known to produce rhamnolipids. PMID:19473254

  18. Establishing a role for bacterial cellulose in environmental interactions: lessons learned from diverse biofilm-producing Proteobacteria

    Directory of Open Access Journals (Sweden)

    Richard Vincent Augimeri

    2015-11-01

    Full Text Available Bacterial cellulose (BC serves as a molecular glue to facilitate intra- and inter-domain interactions in nature. Biosynthesis of BC-containing biofilms occurs in a variety of Proteobacteria that inhabit diverse ecological niches. The enzymatic and regulatory systems responsible for the polymerization, exportation and regulation of BC are equally as diverse. Though the magnitude and environmental consequences of BC production are species-specific, the common role of BC containing biofilms is to establish close contact with a preferred host to facilitate efficient host-bacteria interactions. Universally, BC aids in attachment, adherence, and subsequent colonization of a substrate. Bi-directional interactions influence host physiology, bacterial physiology and regulation of BC biosynthesis, primarily through modulation of intracellular bis-(3’→5’-cyclic diguanylate (c-di-GMP levels. Depending on the circumstance, BC producers exhibit a pathogenic or symbiotic relationship with plant, animal or fungal hosts. Rhizobiaceae species colonize plant roots, Pseudomonadaceae inhabit the phyllosphere, Acetobacteriaceae associate with sugar-loving insects and inhabit the carposphere, Enterobacteriaceae use fresh produce as vehicles to infect animal hosts, and Vibrionaceae, particularly Aliivibrio fischeri, colonize the light organ of squid. This review will highlight the diversity of the biosynthesis and regulation of BC in nature by discussing various examples of Proteobacteria that use BC-containing biofilms to facilitate host-bacteria interactions. Through discussion of current data we will establish new directions for the elucidation of BC biosynthesis, regulation and ecophysiological roles.

  19. Establishing a Role for Bacterial Cellulose in Environmental Interactions: Lessons Learned from Diverse Biofilm-Producing Proteobacteria

    Science.gov (United States)

    Augimeri, Richard V.; Varley, Andrew J.; Strap, Janice L.

    2015-01-01

    Bacterial cellulose (BC) serves as a molecular glue to facilitate intra- and inter-domain interactions in nature. Biosynthesis of BC-containing biofilms occurs in a variety of Proteobacteria that inhabit diverse ecological niches. The enzymatic and regulatory systems responsible for the polymerization, exportation, and regulation of BC are equally as diverse. Though the magnitude and environmental consequences of BC production are species-specific, the common role of BC-containing biofilms is to establish close contact with a preferred host to facilitate efficient host–bacteria interactions. Universally, BC aids in attachment, adherence, and subsequent colonization of a substrate. Bi-directional interactions influence host physiology, bacterial physiology, and regulation of BC biosynthesis, primarily through modulation of intracellular bis-(3′→5′)-cyclic diguanylate (c-di-GMP) levels. Depending on the circumstance, BC producers exhibit a pathogenic or symbiotic relationship with plant, animal, or fungal hosts. Rhizobiaceae species colonize plant roots, Pseudomonadaceae inhabit the phyllosphere, Acetobacteriaceae associate with sugar-loving insects and inhabit the carposphere, Enterobacteriaceae use fresh produce as vehicles to infect animal hosts, and Vibrionaceae, particularly Aliivibrio fischeri, colonize the light organ of squid. This review will highlight the diversity of the biosynthesis and regulation of BC in nature by discussing various examples of Proteobacteria that use BC-containing biofilms to facilitate host–bacteria interactions. Through discussion of current data we will establish new directions for the elucidation of BC biosynthesis, its regulation and its ecophysiological roles. PMID:26635751

  20. Development of a Selective Medium for the Fungal Pathogen Fusarium graminearum Using Toxoflavin Produced by the Bacterial Pathogen Burkholderia glumae

    Directory of Open Access Journals (Sweden)

    Boknam Jung

    2013-12-01

    Full Text Available The ascomycete fungus Fusarium graminearum is a major causal agent for Fusarium head blight in cereals and produces mycotoxins such as trichothecenes and zearalenone. Isolation of the fungal strains from air or cereals can be hampered by various other airborne fungal pathogens and saprophytic fungi. In this study, we developed a selective medium specific to F. graminearum using toxoflavin produced by the bacterial pathogen Burkholderia glumae. F. graminearum was resistant to toxoflavin, while other fungi were sensitive to this toxin. Supplementing toxoflavin into medium enhanced the isolation of F. graminearum from rice grains by suppressing the growth of saprophytic fungal species. In addition, a medium with or without toxoflavin exposed to wheat fields for 1 h had 84% or 25%, respectively, of colonies identified as F. graminearum. This selection medium provides an efficient tool for isolating F. graminearum, and can be adopted by research groups working on genetics and disease forecasting.

  1. Secreted and immunogenic proteins produced by the honeybee bacterial pathogen, Paenibacillus larvae.

    Science.gov (United States)

    Antúnez, Karina; Anido, Matilde; Evans, Jay D; Zunino, Pablo

    2010-03-24

    American Foulbrood is a severe disease affecting larvae of honeybee Apis mellifera, causing significant decrease in the honeybee population, beekeeping industries and agricultural production. In spite of its importance, little is known about the virulence factors secreted by Paenibacillus larvae during larval infection. The aim of the present work was to perform a first approach to the identification and characterization of P. larvae secretome. P. larvae secreted proteins were analyzed by SDS-PAGE and identified by MALDI-TOF. Protein toxicity was evaluated using an experimental model based on feeding of A. mellifera larvae and immunogenicity was evaluated by Western blot, using an antiserum raised against cells and spores of P. larvae. Ten different proteins were identified among P. larvae secreted proteins, including proteins involved in transcription, metabolism, translation, cell envelope, transport, protein folding, degradation of polysaccharides and motility. Although most of these proteins are cytosolic, many of them have been previously detected in the extracellular medium of different Bacillus spp. cultures and have been related to virulence. The secreted proteins resulted highly toxic and immunogenic when larvae were exposed using an experimental model. This is the first description of proteins secreted by the honeybee pathogen P. larvae. This information may be relevant for the elucidation of bacterial pathogenesis mechanisms. PMID:19781868

  2. Caenorhabditis elegans bacterial pathogen resistant bus-4 mutants produce altered mucins.

    Directory of Open Access Journals (Sweden)

    Lisa M Parsons

    Full Text Available Caenorabditis elegans bus-4 glycosyltransferase mutants are resistant to infection by Microbacterium nematophilum, Yersinia pestis and Yersinia pseudotuberculosis and have altered susceptibility to two Leucobacter species Verde1 and Verde2. Our objective in this study was to define the glycosylation changes leading to this phenotype to better understand how these changes lead to pathogen resistance. We performed MALDI-TOF MS, tandem MS and GC/MS experiments to reveal fine structural detail for the bus-4 N- and O-glycan pools. We observed dramatic changes in O-glycans and moderate ones in N-glycan pools compared to the parent strain. Ce core-I glycans, the nematode's mucin glycan equivalent, were doubled in abundance, halved in charge and bore shifts in terminal substitutions. The fucosyl O-glycans, Ce core-II and neutral fucosyl forms, were also increased in abundance as were fucosyl N-glycans. Quantitative expression analysis revealed that two mucins, let-653 and osm-8, were upregulated nearly 40 fold and also revealed was a dramatic increase in GDP-Man 4,6 dehydratease expression. We performed detailed lectin binding studies that showed changes in glycoconjugates in the surface coat, cuticle surface and intestine. The combined changes in cell surface glycoconjugate distribution, increased abundance and altered properties of mucin provide an environment where likely the above pathogens are not exposed to normal glycoconjugate dependent cues leading to barriers to these bacterial infections.

  3. Lactobacillus rhamnosus GG-supplemented formula expands butyrate-producing bacterial strains in food allergic infants.

    Science.gov (United States)

    Berni Canani, Roberto; Sangwan, Naseer; Stefka, Andrew T; Nocerino, Rita; Paparo, Lorella; Aitoro, Rosita; Calignano, Antonio; Khan, Aly A; Gilbert, Jack A; Nagler, Cathryn R

    2016-03-01

    Dietary intervention with extensively hydrolyzed casein formula supplemented with Lactobacillus rhamnosus GG (EHCF+LGG) accelerates tolerance acquisition in infants with cow's milk allergy (CMA). We examined whether this effect is attributable, at least in part, to an influence on the gut microbiota. Fecal samples from healthy controls (n=20) and from CMA infants (n=19) before and after treatment with EHCF with (n=12) and without (n=7) supplementation with LGG were compared by 16S rRNA-based operational taxonomic unit clustering and oligotyping. Differential feature selection and generalized linear model fitting revealed that the CMA infants have a diverse gut microbial community structure dominated by Lachnospiraceae (20.5±9.7%) and Ruminococcaceae (16.2±9.1%). Blautia, Roseburia and Coprococcus were significantly enriched following treatment with EHCF and LGG, but only one genus, Oscillospira, was significantly different between infants that became tolerant and those that remained allergic. However, most tolerant infants showed a significant increase in fecal butyrate levels, and those taxa that were significantly enriched in these samples, Blautia and Roseburia, exhibited specific strain-level demarcations between tolerant and allergic infants. Our data suggest that EHCF+LGG promotes tolerance in infants with CMA, in part, by influencing the strain-level bacterial community structure of the infant gut. PMID:26394008

  4. Preparation of SiC Nanowires Self-sacrificially Templated by Carbonated Bacterial Cellulose%以碳化细菌纤维素为模板制备碳化硅纳米线

    Institute of Scientific and Technical Information of China (English)

    温丽霞; 马拥军

    2012-01-01

    以碳化细菌纤维素为模板和碳源,通过气相渗硅法制备碳化硅纳米线。x射线衍射和扫描电镜(SEM)研究了碳化硅样品的结构与形貌,结果表明所得碳化硅都是纯立方相结构,并且粒度随温度的升高而增大。碳化硅纳米线表面光滑,长度达到微米级。%SiC nanowires were synthesized by the infiltration process of reactive vapor Si, using carbona- ted bacterial cellulose as carbon template and a reactant. XRD and SEM were used to study the phase and morphology of the silicon carbide. The results show that silicon carbide is pure cubic phase and the parti- cle sizes are increasing with the temperature increasing. The surface of SiC nanowires is smooth and the length reaches a micron level.

  5. Oriented single crystalline titanium dioxide nanowires

    International Nuclear Information System (INIS)

    We report the synthesis of oriented single crystalline titanium dioxide (TiO2) nanowire arrays on titanium foil. The synthesis method relies on the ability to grow single crystal sodium titanate (Na2Ti2O5·H2O) nanowires on titanium foil through a novel alkali hydrothermal growth process. Following growth, the Na2Ti2O5·H2O nanowires are converted to protonated bititanate (H2Ti2O5·H2O) nanowires through an ion-exchange reaction without changing their morphology or crystal structure. Finally, the protonated bititanate nanowires are converted to single crystalline anatase TiO2 nanowires through a topotactic transformation by calcination. These three sequential steps yield a carpet of 2-50 μm long single crystalline nanowires oriented in the [100] direction and primarily normal to the titanium foil. Even longer nanowires can be grown. The single crystal TiO2 nanowire arrays on flexible titanium substrate may be used in photocatalytic and photovoltaic devices such as dye-sensitized solar cells and may enhance their performance by providing fast electron transport. The nanowires can also be used as templates for producing hierarchical nanostructures such as nanowires decorated with nanoparticles on their periphery or nanotubes with walls made of nanoparticles.

  6. [Construction and evaluation of an engineered bacterial strain for producing lipopeptide under anoxic conditions].

    Science.gov (United States)

    Liang, Xiao-long; Zhao, Feng; Shi, Rong-jiu; Ban, Yun-he; Zhou, Ji-dong; Han, Si-qin; Zhang, Ying

    2015-08-01

    Biosurfactant-facilitated oil recovery is one of the most important aspects of microbial enhanced oil recovery (MEOR). However, the biosurfactant production by biosurfactant-producing microorganisms, most of which are aerobes, is severely suppressed due to the in-situ anoxic conditions within oil reservoirs. In this research, we successfully engineered a strain JD-3, which could grow rapidly and produce lipopeptide under anoxic conditions, by protoplast confusion using a Bacillus amyloliquefaciens strain BQ-2 which produces biosurfactant aerobically, and a facultative anaerobic Pseudomonas stutzeri strain DQ-1 as parent strains. The alignment of 16S rDNA sequence (99% similarity) and comparisons of cell colony morphology showed that fusant JD-3 was closer to the parental strain B. amyloliquefaciens BQ-2. The surface tension of culture broth of fusant JD-3, after 36-hour cultivation under anaerobic conditions, decreased from initially 63.0 to 32.5 mN · m(-1). The results of thin layer chromatography and infrared spectrum analysis demonstrated that the biosurfactant produced by JD-3 was lipopeptide. The surface-active lipopeptide had a low critical micelle concentration (CMC) of 90 mg · L(-1) and presented a good ability to emulsify various hydrocarbons such as crude oil, liquid paraffin, and kerosene. Strain JD-3 could utilize peptone as nitrogen source and sucrose, glucose, glycerin or other common organics as carbon sources for anaerobic lipopeptide synthesis. The subculture of fusant JD-3 showed a stable lipopeptide-producing ability even after ten serial passages. All these results indicated that fusant JD-3 holds a great potential to microbially enhance oil recovery under anoxic conditions. PMID:26685621

  7. Genome sequencing and systems biology analysis of a lipase-producing bacterial strain.

    Science.gov (United States)

    Li, N; Li, D D; Zhang, Y Z; Yuan, Y Z; Geng, H; Xiong, L; Liu, D L

    2016-01-01

    Lipase-producing bacteria are naturally-occurring, industrially-relevant microorganisms that produce lipases, which can be used to synthesize biodiesel from waste oils. The efficiency of lipase expression varies between various microbial strains. Therefore, strains that can produce lipases with high efficiency must be screened, and the conditions of lipase metabolism and optimization of the production process in a given environment must be thoroughly studied. A high efficiency lipase-producing strain was isolated from the sediments of Jinsha River, identified by 16S rRNA sequence analysis as Serratia marcescens, and designated as HS-L5. A schematic diagram of the genome sequence was constructed by high-throughput genome sequencing. A series of genes related to lipid degradation were identified by functional gene annotation through sequence homology analysis. A genome-scale metabolic model of HS-ML5 was constructed using systems biology techniques. The model consisted of 1722 genes and 1567 metabolic reactions. The topological graph of the genome-scale metabolic model was compared to that of conventional metabolic pathways using a visualization software and KEGG database. The basic components and boundaries of the tributyrin degradation subnetwork were determined, and its flux balance analyzed using Matlab and COBRA Toolbox to simulate the effects of different conditions on the catalytic efficiency of lipases produced by HS-ML5. We proved that the catalytic activity of microbial lipases was closely related to the carbon metabolic pathway. As production and catalytic efficiency of lipases varied greatly with the environment, the catalytic efficiency and environmental adaptability of microbial lipases can be improved by proper control of the production conditions. PMID:27050954

  8. Primordial soup was edible: abiotically produced Miller-Urey mixture supports bacterial growth

    OpenAIRE

    Xueshu Xie; Daniel Backman; Albert T. Lebedev; Viatcheslav B. Artaev; Liying Jiang; Ilag, Leopold L.; Zubarev, Roman A.

    2015-01-01

    Sixty years after the seminal Miller-Urey experiment that abiotically produced a mixture of racemized amino acids, we provide a definite proof that this primordial soup, when properly cooked, was edible for primitive organisms. Direct admixture of even small amounts of Miller-Urey mixture strongly inhibits E. coli bacteria growth due to the toxicity of abundant components, such as cyanides. However, these toxic compounds are both volatile and extremely reactive, while bacteria are highly capa...

  9. Nanowire photonics

    Directory of Open Access Journals (Sweden)

    Peter J. Pauzauskie

    2006-10-01

    Full Text Available The development of integrated electronic circuitry ranks among the most disruptive and transformative technologies of the 20th century. Even though integrated circuits are ubiquitous in modern life, both fundamental and technical constraints will eventually test the limits of Moore's law. Nanowire photonic circuitry constructed from myriad one-dimensional building blocks offers numerous opportunities for the development of next-generation optical information processors and spectroscopy. However, several challenges remain before the potential of nanowire building blocks is fully realized. We cover recent advances in nanowire synthesis, characterization, lasing, integration, and the eventual application to relevant technical and scientific questions.

  10. Rosmarinic acid is a homoserine lactone mimic produced by plants that activates a bacterial quorum-sensing regulator.

    Science.gov (United States)

    Corral-Lugo, Andrés; Daddaoua, Abdelali; Ortega, Alvaro; Espinosa-Urgel, Manuel; Krell, Tino

    2016-01-01

    Quorum sensing is a bacterial communication mechanism that controls genes, enabling bacteria to live as communities, such as biofilms. Homoserine lactone (HSL) molecules function as quorum-sensing signals for Gram-negative bacteria. Plants also produce previously unidentified compounds that affect quorum sensing. We identified rosmarinic acid as a plant-derived compound that functioned as an HSL mimic. In vitro assays showed that rosmarinic acid bound to the quorum-sensing regulator RhlR of Pseudomonas aeruginosa PAO1 and competed with the bacterial ligand N-butanoyl-homoserine lactone (C4-HSL). Furthermore, rosmarinic acid stimulated a greater increase in RhlR-mediated transcription in vitro than that of C4-HSL. In P. aeruginosa, rosmarinic acid induced quorum sensing-dependent gene expression and increased biofilm formation and the production of the virulence factors pyocyanin and elastase. Because P. aeruginosa PAO1 infection induces rosmarinic acid secretion from plant roots, our results indicate that rosmarinic acid secretion is a plant defense mechanism to stimulate a premature quorum-sensing response. P. aeruginosa is a ubiquitous pathogen that infects plants and animals; therefore, identification of rosmarinic acid as an inducer of premature quorum-sensing responses may be useful in agriculture and inform human therapeutic strategies. PMID:26732761

  11. Effect of PGR producing bacterial strains isolated from vermisources on germination and growth of Vigna unguiculata (L. Walp.

    Directory of Open Access Journals (Sweden)

    Anandharaj Marimuthu

    2014-12-01

    Full Text Available Nineteen bacterial strains were isolated from vermisources andscreened for Indole-3-acetic acid (IAA production among themonly nine strains produce IAA and they were identified asStreptococcus spp., Micrococcus spp., Klebsiella spp., Bacillus spp., Enterobacter spp., Escherichia spp., Alcaligenes spp., Erwinia spp., and Pseudomonas spp. Among all other strains Bacillus sp. showed the higher IAA production hence selected for further molecular analysis and confirmed as Bacillus cereus. The B. cereus was grown in nutrient broth supplemented with different concentrations (1, 2, 3, 4 and 5mg/ml of tryptophan for seven days at pH 7 and at 37ºC. Crude IAA was used for in vitro phytostimulatory studies using Vigna unguiculata (L. Walp. The plant growth parameters were analyzed at different day intervals (5, 10 and 15 days. Supplementation of 5 ml crude IAA (2mg/ml of tryptophan dynamically enhances the plant growth parameters after 15 days.

  12. Optimization of biohydrogen yield produced by bacterial consortia using residual glycerin from biodiesel production.

    Science.gov (United States)

    Faber, Mariana de Oliveira; Ferreira-Leitão, Viridiana Santana

    2016-11-01

    The aims of this study were to simplify the fermentation medium and to optimize the conditions of dark fermentation of residual glycerin to produce biohydrogen. It was possible to remove all micronutrients of fermentation medium and improve biohydrogen production by applying residual glycerin as feedstock. After statistical analysis of the following parameters pH, glycerin concentration and volatile suspended solids, the values of 5.5; 0.5g.L(-1) and 8.7g.L(-1), respectively, were defined as optimum condition for this process. It generated 2.44molH2/molglycerin, an expressive result when compared to previous results reported in literature and considering that theoretical yield of H2 from glycerol in dark fermentation process is 3molH2/molglycerol. This study allowed the improvement of yield and productivity by 68% and 67%, respectively. PMID:27501033

  13. Study on Screening and Cultivation Conditions of Xylanase-Producing Alkalophilic Bacterial

    Institute of Scientific and Technical Information of China (English)

    Han Xiao-fang; Zheng Lian-shuang; Xie Yi-min

    2004-01-01

    An xylanase producting alkalophilic Bacillus NT-9 was obtaind by the screening method of transparent zone on the selective medium, and the effects of carbon source and nitrogen source on xylanase production were studied. The medium composed of xylose 1.5%, (NH4)2SO4 0.25%, K2HPO4 0.1%, MgSO4·7H2O 0.02%, with the initial pH of 10, was suggested to be optimal for the enzyme production in this study. When cultivatied at 37 ℃ for 72 h, the enzyme activity elaborated by the strain may reach as high as 10.5 U/mL. The xylanase produced by Bacillus NT-9 was a constituent enzyme.

  14. Characterization of novel extracellular protease produced by marine bacterial isolate from the Indian Ocean

    Directory of Open Access Journals (Sweden)

    Rachana Fulzele

    2011-12-01

    Full Text Available Out of the vast pool of enzymes, proteolytic enzymes from microorganisms are the most widely used in different industries such as detergent, food, peptide production etc. Several marine microorganisms are known to produce proteases with commercially desirable characteristics. We have isolated nine different cultures from marine samples of the Indian Ocean. All of them were i motile ii rod shaped iii non spore forming iv catalase and amylase positive v able to grow in presence of 10 % NaCl. They produced acid from glucose, fructose and maltose and grew optimally at 30 0C temperature and pH 7.0-8.0. None of them could grow above 45 0C and below 15 0C. Only one of them (MBRI 7 exhibited extracellular protease activity on skim milk agar plates. Based on 16S rDNA sequencing, it belonged to the genus Marinobacter (98% sequence similarity, 1201 bp. The cell free extract was used to study effects of temperature and pH on protease activity. The optimum temperature and pH for activity were found to be 40 0C and 7.0 respectively. The crude enzyme was stable at temperature range of 30-80 0C and pH 5.0-9.0. It retained 60 % activity at 80 0C after 4 h and more than 70 % activity at 70 0C after 1 h. D value was found to be 342 minutes and 78 minutes for 40 0C and 80 0C respectively. Interestingly the enzyme remained 50 % active at pH 9.0 after 1 h. Comparison with other proteases from different microbial sources indicated that the neutral protease from the halotolerant marine isolate MBRI 7 is a novel enzyme with high thermostability.

  15. Nanowire Lasers

    Science.gov (United States)

    Couteau, C.; Larrue, A.; Wilhelm, C.; Soci, C.

    2015-05-01

    We review principles and trends in the use of semiconductor nanowires as gain media for stimulated emission and lasing. Semiconductor nanowires have recently been widely studied for use in integrated optoelectronic devices, such as light-emitting diodes (LEDs), solar cells, and transistors. Intensive research has also been conducted in the use of nanowires for subwavelength laser systems that take advantage of their quasione- dimensional (1D) nature, flexibility in material choice and combination, and intrinsic optoelectronic properties. First, we provide an overview on using quasi-1D nanowire systems to realize subwavelength lasers with efficient, directional, and low-threshold emission. We then describe the state of the art for nanowire lasers in terms of materials, geometry, andwavelength tunability.Next,we present the basics of lasing in semiconductor nanowires, define the key parameters for stimulated emission, and introduce the properties of nanowires. We then review advanced nanowire laser designs from the literature. Finally, we present interesting perspectives for low-threshold nanoscale light sources and optical interconnects. We intend to illustrate the potential of nanolasers inmany applications, such as nanophotonic devices that integrate electronics and photonics for next-generation optoelectronic devices. For instance, these building blocks for nanoscale photonics can be used for data storage and biomedical applications when coupled to on-chip characterization tools. These nanoscale monochromatic laser light sources promise breakthroughs in nanophotonics, as they can operate at room temperature, can potentially be electrically driven, and can yield a better understanding of intrinsic nanomaterial properties and surface-state effects in lowdimensional semiconductor systems.

  16. Anti-bacterial selenium nanoparticles produced by UV/VIS/NIR pulsed nanosecond laser ablation in liquids

    International Nuclear Information System (INIS)

    The ability to produce nanoparticles free of any surface contamination is very challenging especially for bio-medical applications. Using a pulsed nanosecond Nd-YAG laser, pure selenium nanoparticles have been synthesized by irradiating selenium powder (99.999%) immerged in de-ionized water and ethanol. The wavelength of the laser beam has been varied from the UV to NIR (355, 532 and 1064 nm) and its effect on the particle size distribution has been studied by dynamic light scattering (DLS) and transmission electronic microscopy (TEM), revealing then the production of selenium quantum dots (size < 4 nm) by photo-fragmentation. It has been found that the crystallinity of the nanoparticles depends on their size. The zeta-potential measurement reveals that the colloidal solutions produced in de-ionized water were stable while the ones synthesized in ethanol agglomerate. The concentration of selenium has been measured using inductively coupled plasma mass spectrometry (ICP-MS). The anti-bacterial effect of selenium nanostructures has been analyzed on E. Coli bacteria. Finally, selenium quantum dots produced by this method can also be useful for quantum dot solar cells. (letter)

  17. Pestalone, a new antibiotic produced by a marine fungus in response to bacterial challenge.

    Science.gov (United States)

    Cueto, M; Jensen, P R; Kauffman, C; Fenical, W; Lobkovsky, E; Clardy, J

    2001-11-01

    The isolation and structure determination of a new chlorinated benzophenone antibiotic, pestalone (1), is described. The new compound was produced by a cultured marine fungus only when a unicellular marine bacterium, strain CNJ-328, was co-cultured in the fungal fermentation. The fungus, isolated from the surface of the brown alga Rosenvingea sp. collected in the Bahamas Islands, was identified as an undescribed member of the genus Pestalotia. The structure of 1, initially assigned with only modest confidence by combined spectral and chemical data, was confirmed by single-crystal X-ray analysis. Pestalone (1) exhibits moderate in vitro cytotoxicity in the National Cancer Institute's 60 human tumor cell line screen (mean GI(50) = 6.0 microM). More importantly, pestalone shows potent antibiotic activity against methicillin-resistant Staphylococcus aureus (MIC = 37 ng/mL) and vancomycin-resistant Enterococcus faecium (MIC = 78 ng/mL), indicating that pestalone should be evaluated in advanced models of infectious disease. PMID:11720529

  18. Lithographically patterned nanowire electrodeposition

    Science.gov (United States)

    Xiang, Chengxiang

    Lithographically patterned nanowire electrodeposition (LPNE) is a new method for fabricating polycrystalline metal nanowires using electrodeposition. In LPNE, a sacrificial metal (M1 = silver or nickel) layer, 5 - 100 nm in thickness, is first vapor deposited onto a glass, oxidized silicon, or Kapton polymer film. A photoresist (PR) layer is then deposited, photopatterned, and the exposed Ag or Ni is removed by wet etching. The etching duration is adjusted to produce an undercut ≈300 nm in width at the edges of the exposed PR. This undercut produces a horizontal trench with a precisely defined height equal to the thickness of theM1 layer. Within this trench, a nanowire of metal M2 is electrodeposited (M2 = gold, platinum, palladium, or bismuth). Finally the PR layer and M1 layer are removed. The nanowire height and width can be independently controlled down to minimum dimensions of 5 nm (h) and 11 nm (w), for example, in the case of platinum. These nanowires can be 1 cm in total length. We measure the temperature-dependent resistance of 100 um sections of Au and Pd wires in order to estimate an electrical grain size for comparison with measurements by X-ray diffraction and transmission electron microscopy. Nanowire arrays can be postpatterned to produce two-dimensional arrays of nanorods. Nanowire patterns can also be overlaid one on top of another by repeating the LPNE process twice in succession to produce, for example, arrays of low-impedance, nanowirenanowire junctions. The resistance, R, of single gold nanowires was measured in situ during electrooxidation in aqueous 0.10 M sulfuric acid. Electrooxidation caused the formation of a gold oxide that is approximately 0.8 monolayers (ML) in thickness at +1.1 V vs saturated mercurous sulfate reference electrode (MSE) based upon coulometry and ex situ X-ray photoelectron spectroscopic analysis. As the gold nanowires were electrooxidized, R increased by an amount that depended on the wire thickness, ranging from

  19. Exploration and conservation of bacterial genetic resources as bacteriocin producing inhibitory microorganisms to pathogen bacteria in livestock

    Directory of Open Access Journals (Sweden)

    Chotiah S

    2013-06-01

    Full Text Available Exploration and conservation of microorganisms producing bacteriocin was done as the primary study towards the collection of potential bacteria and its application in improving livestock health condition and inhibit food borne pathogens. Diferent kinds of samples such as beef cattle rectal swab, rumen fluids, cow’s milk, chicken gut content, goat’s milk were collected at Bogor cattle slaughter houses, poultry slaughter houses, dairy cattle and goat farms. A total of 452 bacterial isolates consisted of 73 Gram negative bacteria and 379 Gram positive bacteria were isolated from samples collected and screened for bacteriocin activity. Determination of bacteriocin activity with bioassay using agar spot tests were carried out on liquid and semisolid medium assessing 8 kins of indicators of pathogenic bacteria and food borne pathogens. A total of 51 bacteriocin producing strains were collected and some of the strains had high inhibitory zone such as Lactobacillus casei SS14C (26 mm, Enterobacter cloacae SRUT (24mm, Enterococcus faecalis SK39 (21mm and Bifidobacterium dentium SS14T (20mm respectively, to Salmonella typhimurium BCC B0046/ATCC 13311, E. coli O157 hemolytic BCC B2717, Listeria monocytogenes BCC B2767/ATCC 7764 and Escherichia coli VTEC O157 BCC B2687. Evaluation after conservation ex situ to all bacterocin producing strain at 5oC for 1 year in freeze drying ampoules in vacuum and dry condition revealed the decreasing viability starting from log 0.8 CFU/ml for Lactococcus and Leuconostoc to log 2.2. CFU/ml for Streptococcus. Result of the study showed that the bacteriocin producing strains obtained were offered a potential resource for preventing disease of livestock and food borne diseases.

  20. Effects of bacterially produced precipitates on the metabolism of sulfate reducing bacteria during the bio-treatment process of copper-containing wastewater

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A large volume of bacterially produced precipitates are generated during the bio-treatment of heavy metal wastewater.The composition of the bacterially produced precipitates and its effects on sulfate reducing bacteria (SRB) in copper-containing waste stream were evaluated in this study.The elemental composition of the microbial precipitate was studied using electrodispersive X-ray spectroscopy (EDX),and it was found that the ratio of S:Cu was 1.12.Combining with the results of copper distribution in the SRB metabolism culture,which was analyzed by the sequential extraction procedure,copper in the precipitates was determined as covellite (CuS).The bacterially produced precipitates caused a decrease of the sulfate reduction rate,and the more precipitates were generated,the lower the sulfate reduction rate was.The particle sizes of bacterially generated covellite were ranging from 0.03 to 2 m by particles size distribution (PSD) analysis,which was smaller than that of the SRB cells.Transmission electron microscopy (TEM) analysis showed that the microbial covellite was deposited on the surface of the cell.The effects of the microbial precipitate on SRB metabolism were found to be weakened by increasing the precipitation time and adding microbial polymeric substances in later experiments.These results provided direct evidence that the SRB activity was inhibited by the bacterially produced covellite,which enveloped the bacterium and thus affected the metabolism of SRB on mass transfer.

  1. Strong ionisation in carbon nanowires

    Science.gov (United States)

    Kaymak, V.; Pukhov, A.; Shlyaptsev, V. N.; Rocca, J. J.

    2016-04-01

    Surfaces covered with nanostructures, such as nanowire arrays, are shown to facilitate a significantly higher absorption of laser energy as compared to flat surfaces. Due to the efficient coupling of the laser energy, highly energetic electrons are produced, which in turn can emit intense ultrafast X-ray pulses. Full three dimensional PIC simulations are used to analyse the behaviour of arrays of carbon nanowires 400 nm in diameter, irradiated by a 400-nm laser pulse of 60-fs duration at FWHM and a vector potential of α0 = 18. We analyse the ionisation dynamics of the nanowires. The difference of the ionisation strength and structure between linearly and circularly polarised laser beam is investigated. The nanowires are found to be fully ionised after about 30 laser cycles. Circularly polarised light reveals a slightly stronger ionisation effect.

  2. Strong Ionization in carbon Nanowires

    CERN Document Server

    Kaymak, Vural; Shlyaptsev, Vyacheslav N; Rocca, Jorge J

    2015-01-01

    Surfaces covered with nanostructures, such as nanowire arrays, have shown to facilitate a significantly higher absorption of laser energy as compared to flat surfaces. Due to the efficient coupling of the laser energy, highly energetic electrons are produced, which in turn can emit intense ultrafast X-ray pulses. In the present work we use full three dimensional PIC simulations to analyze the behavior of arrays of carbon nanowires $400 nm$ in diameter, irradiated by a $\\lambda_0 = 400 nm$ laser pulse of $60 fs$ duration at FWHM and a vector potential of $a_0 = 18$. We analyze the ionization dynamics of the nanowires. We investigate the difference of the ionization strength and structure between linearly and circularly polarized laser beam. The nanowires are found to be fully ionized after about 30 laser cycles. Circularly polarized light reveals a slightly stronger ionization effect.

  3. Hemolysin, Protease, and EPS Producing Pathogenic Aeromonas hydrophila Strain An4 Shows Antibacterial Activity against Marine Bacterial Fish Pathogens

    Directory of Open Access Journals (Sweden)

    Anju Pandey

    2010-01-01

    Full Text Available A pathogenic Aeromonas hydrophila strain An4 was isolated from marine catfish and characterized with reference to its proteolytic and hemolytic activity along with SDS-PAGE profile (sodium dodecyl sulphate-Polyacrylamide gel electrophoresis of ECPs (extracellular proteins showing hemolysin (approximately 50 kDa. Agar well diffusion assay using crude cell extract of the bacterial isolate clearly demonstrated antibacterial activity against indicator pathogenic bacteria, Staphylococcus arlettae strain An1, Acinetobacter sp. strain An2, Vibrio parahaemolyticus strain An3, and Alteromonas aurentia SE3 showing inhibitory zone >10 mm well comparable to common antibiotics. Further GC-MS analysis of crude cell extract revealed several metabolites, namely, phenolics, pyrrolo-pyrazines, pyrrolo-pyridine, and butylated hydroxytoluene (well-known antimicrobials. Characterization of EPS using FTIR indicated presence of several protein-related amine and amide groups along with peaks corresponding to carboxylic and phenyl rings which may be attributed to its virulent and antibacterial properties, respectively. Besides hemolysin, EPS, and protease, Aeromonas hydrophila strain An4 also produced several antibacterial metabolites.

  4. Characterization of geographically distinct bacterial communities associated with coral mucus produced by Acropora spp. and Porites spp.

    Science.gov (United States)

    McKew, B A; Dumbrell, A J; Daud, S D; Hepburn, L; Thorpe, E; Mogensen, L; Whitby, C

    2012-08-01

    Acropora and Porites corals are important reef builders in the Indo-Pacific and Caribbean. Bacteria associated with mucus produced by Porites spp. and Acropora spp. from Caribbean (Punta Maroma, Mexico) and Indo-Pacific (Hoga and Sampela, Indonesia) reefs were determined. Analysis of pyrosequencing libraries showed that bacterial communities from Caribbean corals were significantly more diverse (H', 3.18 to 4.25) than their Indonesian counterparts (H', 2.54 to 3.25). Dominant taxa were Gammaproteobacteria, Alphaproteobacteria, Firmicutes, and Cyanobacteria, which varied in relative abundance between coral genera and region. Distinct coral host-specific communities were also found; for example, Clostridiales were dominant on Acropora spp. (at Hoga and the Mexican Caribbean) compared to Porites spp. and seawater. Within the Gammproteobacteria, Halomonas spp. dominated sequence libraries from Porites spp. (49%) and Acropora spp. (5.6%) from the Mexican Caribbean, compared to the corresponding Indonesian coral libraries (coral mucus. In addition, the predominance of Clostridiales associated with Acropora spp. provided additional evidence for coral host-specific microorganisms. PMID:22636010

  5. Effects of interactions of auxin-producing bacteria and bacterial-feeding nematodes on regulation of peanut growths.

    Science.gov (United States)

    Xu, Li; Xu, Wensi; Jiang, Ying; Hu, Feng; Li, Huixin

    2015-01-01

    The influences of an IAA (indole-3-acetic acid)-producing bacterium (Bacillus megaterium) and two bacterial-feeding nematodes (Cephalobus sp. or Mesorhabditis sp.) on the growth of peanut (Arachis hypogaea L. cv. Haihua 1) after various durations of time were investigated in natural soils. The addition of bacteria and nematodes and incubation time all significantly affected plant growth, plant root growth, plant nutrient concentrations, soil nutrient concentrations, soil microorganisms and soil auxin concentration. The addition of nematodes caused greater increases in these indices than those of bacteria, while the addition of the combination of bacteria and nematodes caused further increases. After 42-day growth, the increases in soil respiration differed between the additions of two kinds of nematodes because of differences in their life strategies. The effects of the bacteria and nematodes on the nutrient and hormone concentrations were responsible for the increases in plant growth. These results indicate the potential for promoting plant growth via the addition of nematodes and bacteria to soil. PMID:25867954

  6. Effects of interactions of auxin-producing bacteria and bacterial-feeding nematodes on regulation of peanut growths.

    Directory of Open Access Journals (Sweden)

    Li Xu

    Full Text Available The influences of an IAA (indole-3-acetic acid-producing bacterium (Bacillus megaterium and two bacterial-feeding nematodes (Cephalobus sp. or Mesorhabditis sp. on the growth of peanut (Arachis hypogaea L. cv. Haihua 1 after various durations of time were investigated in natural soils. The addition of bacteria and nematodes and incubation time all significantly affected plant growth, plant root growth, plant nutrient concentrations, soil nutrient concentrations, soil microorganisms and soil auxin concentration. The addition of nematodes caused greater increases in these indices than those of bacteria, while the addition of the combination of bacteria and nematodes caused further increases. After 42-day growth, the increases in soil respiration differed between the additions of two kinds of nematodes because of differences in their life strategies. The effects of the bacteria and nematodes on the nutrient and hormone concentrations were responsible for the increases in plant growth. These results indicate the potential for promoting plant growth via the addition of nematodes and bacteria to soil.

  7. Identification of a New Marine Bacterial Strain SD8 and Optimization of Its Culture Conditions for Producing Alkaline Protease.

    Directory of Open Access Journals (Sweden)

    Hongxia Cui

    Full Text Available While much attention has been given to marine microorganisms for production of enzymes, which in general are relatively more stable and active compared to those from plants and animals, studies on alkaline protease production from marine microorganisms have been very limited. In the present study, the alkaline protease producing marine bacterial strain SD8 isolated from sea muds in the Geziwo Qinhuangdao sea area of China was characterized and its optimal culture conditions were investigated. Strain SD8 was initially classified to belong to genus Pseudomonas by morphological, physiological and biochemical characterizations, and then through 16S rDNA sequence it was identified to be likely Pseudomonas hibiscicola. In addition, the culture mediums, carbon sources and culture conditions of strain SD8 were optimized for maximum production of alkaline protease. Optimum enzyme production (236U/mL when cultured bacteria being at 0.75 mg dry weight/mL fermentation broth was obtained when the isolate at a 3% inoculum size was grown in LB medium at 20 mL medium/100mL Erlenmeyer flask for 48h culture at 30°C with an initial of pH 7.5. This was the first report of strain Pseudomonas hibiscicola secreting alkaline protease, and the data for its optimal cultural conditions for alkaline protease production has laid a foundation for future exploration for the potential use of SD8 strain for alkaline protease production.

  8. Identification of a New Marine Bacterial Strain SD8 and Optimization of Its Culture Conditions for Producing Alkaline Protease.

    Science.gov (United States)

    Cui, Hongxia; Yang, Muyang; Wang, Liping; Xian, Cory J

    2015-01-01

    While much attention has been given to marine microorganisms for production of enzymes, which in general are relatively more stable and active compared to those from plants and animals, studies on alkaline protease production from marine microorganisms have been very limited. In the present study, the alkaline protease producing marine bacterial strain SD8 isolated from sea muds in the Geziwo Qinhuangdao sea area of China was characterized and its optimal culture conditions were investigated. Strain SD8 was initially classified to belong to genus Pseudomonas by morphological, physiological and biochemical characterizations, and then through 16S rDNA sequence it was identified to be likely Pseudomonas hibiscicola. In addition, the culture mediums, carbon sources and culture conditions of strain SD8 were optimized for maximum production of alkaline protease. Optimum enzyme production (236U/mL when cultured bacteria being at 0.75 mg dry weight/mL fermentation broth) was obtained when the isolate at a 3% inoculum size was grown in LB medium at 20 mL medium/100mL Erlenmeyer flask for 48h culture at 30°C with an initial of pH 7.5. This was the first report of strain Pseudomonas hibiscicola secreting alkaline protease, and the data for its optimal cultural conditions for alkaline protease production has laid a foundation for future exploration for the potential use of SD8 strain for alkaline protease production. PMID:26716833

  9. Crystalline bacterial biofilm formation on urinary catheters by urease-producing urinary tract pathogens: a simple method of control.

    Science.gov (United States)

    Broomfield, Robert J; Morgan, Sheridan D; Khan, Azhar; Stickler, David J

    2009-10-01

    The problem of catheter encrustation stems from infection by urease-producing bacteria. These organisms generate ammonia from urea, elevate the pH of urine and cause crystals of calcium and magnesium phosphates to form in the urine and the biofilm that develops on the catheter. In this study, a laboratory model was used to compare the ability of 12 urease-positive species of urinary tract pathogens to encrust and block catheters. Proteus mirabilis, Proteus vulgaris and Providencia rettgeri were able to raise the urinary pH above 8.3 and produce catheter-blocking crystalline biofilms within 40 h. Morganella morganii and Staphylococcus aureus elevated the pH of urine to 7.4 and 6.9, respectively, and caused some crystal deposition in the biofilms but did not block catheters in the 96 h experimental period. Isolates of Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter cloacae, Serratia marcescens, Pseudomonas aeruginosa and Providencia stuartii were only capable of raising the pH of urine to a maximum of 6.4 and failed to cause crystal deposition in the biofilm. The most effective way to prevent catheter encrustation was shown to be diluting urine and increasing its citrate concentration. This strategy raises the nucleation pH (pH(n)) at which calcium and magnesium phosphates crystallize from urine. Increasing the fluid intake of a healthy volunteer with citrated drinks resulted in urine with a pH(n) of >8.0 in which catheter encrustation was inhibited. It is suggested that this dietary strategy will be an effective means of controlling catheter encrustation, whichever bacterial species is causing the problem. PMID:19556373

  10. Quantitative polymerase chain reaction (PCR) assays for a bacterial thiaminase I gene and the thiaminase-producing bacterium Paenibacillus thiaminolyticus.

    Science.gov (United States)

    Richter, C.A.; Wright-Osment, Maureen K.; Zajicek, J.L.; Honeyfield, D.C.; Tillitt, D.E.

    2009-01-01

    The thiaminase I enzyme produced by the gram-positive bacterium Paenibacillus thiaminolyticus isolated from the viscera of Lake Michigan alewives Alosa pseudoharengus is currently the only defined source of the thiaminase activity linked to thiamine (vitamin B1) deficiency in early mortality syndrome (EMS) in the larvae of Great Lakes salmonines. Diets of alewife or isolated strains of P. thiaminolyticus mixed in a semipurified diet and fed to lake trout Salvelinus namaycush have been shown to produce EMS in fry. We utilized quantitative polymerase chain reaction (Q-PCR) to aid in studies of the sources of P. thiaminolyticus and thiaminase I. Quantitative PCR assays were established to detect the thiaminase I gene of P. thiaminolyticus, the 16S rRNA gene from most species of bacteria, and the 16S rRNA gene specifically from P. thiaminolyticus and a few closely related taxa. The Q-PCR assays are linear over at least six orders of magnitude and can detect the thiaminase I gene of P. thiaminolyticus from as few as 1,000 P. thiaminolyticus cells/g of sample or the Paenibacillus 16S rRNA gene from as few as 100 P. thiaminolyticus cells/g of sample. The initial results from alewife viscera samples with high thiaminase activity yielded unexpectedly low densities of P. thiaminolyticus cells; Paenibacillus thiaminolyticus was detectable in 2 of 6 alewife viscera tested at densities on the order of 100 cells/g out of 100,000,000 total bacterial cells/g. The low numbers of P. thiaminolyticus detected suggest that alewives contain additional non-P. thiaminolyticus sources of thiaminase activity.

  11. Mechanism of Excretion of a Bacterial Proteinase: Demonstration of Two Proteolytic Enzymes Produced by a Sarcina Strain (Coccus P)

    Energy Technology Data Exchange (ETDEWEB)

    SARNER, NITZA Z; BISSELL, MINA J; GIROLAMO, MARIO Di; GORINI, LUIGI

    1970-06-29

    A Sarcina strain (Coccus P) produces two proteolytic enzymes. One is found only extracellularly, is far more prevalent, and is actively excreted during exponential growth. It is the enzyme responsible for the known strong proteolytic activity of the cultures of this strain. A second protease is, however, produced which remains associated with the intact cells but is released by the protoplasts. The two enzymes appear unrelated in their derivation. Calcium ions play an essential role in preventing autodigestion of the excreted enzyme. Bacterial proteins are found outside the cell boundary as a consequence either of passive processes such as leakage or lysis or of active excretion. Under conditions in which leakage and lysis do not occur, as during exponential growth, the cell boundary is a barrier causing a complete separation of the bulk of the intracellular proteins from the one or very few extracellular proteins, with no trace of either type being detectable on the wrong side of the boundary. Since in bacteria there is no evidence of protein being produced other than internally, the separation into intraand extracellular proteins should occur after peptide chain formation. The question arises as to whether the structure of the cell boundary or that of the excreted proteins themselves determines this separation. Coccus P, a Sarcina closely related to Micrococcus lysodeikticus (3), produces an extracellular proteinase during the exponential phase of growth so that the process appears to be active excretion. The organism grows exponentially in a defined synthetic medium (12) to relatively high cell density (10{sup 9} cells/ml); therefore the mechanism of excretion can be studied over an extended period of time without the difficulties of changing growth rates. Coagulation of reconstituted skim milk provides a simple and sensitive assay for enzyme activity (I 1). The extracellular proteinase has also been purified and partially characterized (6-8). It has been shown

  12. Raman spectroscopy of WO3 nano-wires and thermo-chromism study of VO2 belts produced by ultrasonic spray and laser pyrolysis techniques

    International Nuclear Information System (INIS)

    Novel optical and electrical properties of newly synthesized nano-wires of monoclinic WO3 and nano-belts of rutile VO2 have been investigated by Raman spectroscopy and thermo-chromism studies respectively. Phonon confinement is observed in the WO3 nano-wires and the previously modified Richter equation is fitted to the experimental Raman spectroscopy data to obtain the optical phonon dispersion relations for the 713 cm-1 branch and the 808 cm-1 branch of WO3 phonon spectra for the first time. Electrical measurements on the VO2 nano-belts at varying temperature reveal an enhanced hysteresis width of about 83 C surpassing previously reported values on the thermo-chromism studies on VO2. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Mixed biofilm formation by Shiga toxin-producing Escherichia coli and Salmonella enterica serovar typhimurium enhanced bacterial resistance to sanitization due to extracellular polymeric substances

    Science.gov (United States)

    Shiga toxin–producing Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium are important foodborne pathogens capable of forming single-species biofilms or coexisting in multispecies biofilm communities. Bacterial biofilm cells are usually more resistant to sanitization than their pla...

  14. Isolation and Identification of a New Tetrodotoxin-Producing Bacterial Species, Raoultella terrigena, from Hong Kong Marine Puffer Fish Takifugu niphobles

    Directory of Open Access Journals (Sweden)

    Fred Wang-Fat Lee

    2011-11-01

    Full Text Available Puffer fish, Takifugu niphobles, collected from the Hong Kong coastal waters were screened for tetrodotoxin-producing bacteria. A Gram-negative, non-acid-fast, non-sporing and rod shaped bacterial strain (designated as gutB01 was isolated from the intestine of the puffer fish and was shown to produce tetrodotoxin (TTX. Based on the Microbial Identification (MIDI and 16S-23S rDNA internal transcribed spacer (ITS phylogenetic analysis, the strain was identified as Raoultella terrigena. The TTX production ability of the strain was confirmed by mouse bioassay, ELISA and mass spectrometry (MALDI-TOF. Our results reiterate that the TTX found in puffer fish was likely produced by the associated bacteria and TTX are widely produced amongst a diversity of bacterial species.

  15. The population structure of antibiotic-producing bacterial symbionts of Apterostigma dentigerum ants: impacts of coevolution and multipartite symbiosis.

    Science.gov (United States)

    Caldera, Eric J; Currie, Cameron R

    2012-11-01

    Fungus-growing ants (Attini) are part of a complex symbiosis with Basidiomycetous fungi, which the ants cultivate for food, Ascomycetous fungal pathogens (Escovopsis), which parasitize cultivars, and Actinobacteria, which produce antibiotic compounds that suppress pathogen growth. Earlier studies that have characterized the association between attine ants and their bacterial symbionts have employed broad phylogenetic approaches, with conclusions ranging from a diffuse coevolved mutualism to no specificity being reported. However, the geographic mosaic theory of coevolution proposes that coevolved interactions likely occur at a level above local populations but within species. Moreover, the scale of population subdivision is likely to impact coevolutionary dynamics. Here, we describe the population structure of bacteria associated with the attine Apterostigma dentigerum across Central America using multilocus sequence typing (MLST) of six housekeeping genes. The majority (90%) of bacteria that were isolated grouped into a single clade within the genus Pseudonocardia. In contrast to studies that have suggested that Pseudonocardia dispersal is high and therefore unconstrained by ant associations, we found highly structured ([Formula: see text]) and dispersal-limited (i.e., significant isolation by distance; [Formula: see text], [Formula: see text]) populations over even a relatively small scale (e.g., within the Panama Canal Zone). Estimates of recombination versus mutation were uncharacteristically low compared with estimates for free-living Actinobacteria (e.g., [Formula: see text] in La Selva, Costa Rica), which suggests that recombination is constrained by association with ant hosts. Furthermore, Pseudonocardia population structure was correlated with that of Escovopsis species ([Formula: see text], [Formula: see text]), supporting the bacteria's role in disease suppression. Overall, the population dynamics of symbiotic Pseudonocardia are more consistent with a

  16. Feasibility of EPS-producing bacterial inoculation to speed up the sand aggregation in the Gurbantunggut Desert, Northwestern China.

    Science.gov (United States)

    Wu, Nan; Pan, Hui-Xia; Qiu, Dong; Zhang, Yuan-Ming

    2014-12-01

    Exopolymers are known to be useful in improving sand aggregation and the development of biological soil crusts (BSCs). A facultative bacterium KLBB0001 was isolated from BSCs in the Gurbantunggut Desert in northwestern China. With the strong effective production of extracellular polymeric substances (EPS), this strain exhibits a multifunctional role for sand stabilization and maintenance of water under laboratory conditions. Practical testing of the feasibility of its inoculation to speed up BSC recovery in the field was also conducted in this experiment. This strain stimulated the heterotrophic community assembly in the topsoil layer (0-2 cm) before the commencement of autotrophic cyanobacteria, while also significantly increasing the number of bacteria, actinomycetes, and content of total phosphorus, available nitrogen, and available phosphorus. However, the low nitrogenase activity (NA) (0.57 µmol/h) that was observed caused us to doubt the previous identification as Azotobacter Beijerinck that was based on physiological and biochemical properties. A phylogenetic analysis based on 16S rRNA gene sequences revealed that this strain was a member of the genus Paenibacillus. It exhibited the closest phylogenetic affinity and highest sequence similarity to the strain Paenibacillus mucilaginosus VKPM B-7519 (sequence similarity 99.698%), which is well known as a typical silicate-weathering bacteria that releases lots of nutritional ions from minerals and the soil. Because P. mucilaginosus can excrete carbonic anhydrase (CA) to capture atmospheric CO2 through hydration of CO2 , it is possible that KLBB0001 might use a similar strategy for heterotrophs in the BSCs to sequester CO2 from the air. Because of its potential role in the reestablishment of the BSC ecosystem due to its ability to improve water relations, sand stabilization, and chemical erosion, EPS-producing bacterial inoculation was concluded to be a suitable and effective treatment for BSC recovery

  17. Nanowire photonics

    OpenAIRE

    Peter J. Pauzauskie; Peidong Yang

    2006-01-01

    The development of integrated electronic circuitry ranks among the most disruptive and transformative technologies of the 20th century. Even though integrated circuits are ubiquitous in modern life, both fundamental and technical constraints will eventually test the limits of Moore's law. Nanowire photonic circuitry constructed from myriad one-dimensional building blocks offers numerous opportunities for the development of next-generation optical information processors and spectroscopy. Howev...

  18. Nanowire Optoelectronics

    Science.gov (United States)

    Wang, Zhihuan; Nabet, Bahram

    2015-12-01

    Semiconductor nanowires have been used in a variety of passive and active optoelectronic devices including waveguides, photodetectors, solar cells, light-emitting diodes (LEDs), lasers, sensors, and optical antennas. We review the optical properties of these nanowires in terms of absorption, guiding, and radiation of light, which may be termed light management. Analysis of the interaction of light with long cylindrical/hexagonal structures with subwavelength diameters identifies radial resonant modes, such as Leaky Mode Resonances, or Whispering Gallery modes. The two-dimensional treatment should incorporate axial variations in "volumetric modes,"which have so far been presented in terms of Fabry-Perot (FP), and helical resonance modes. We report on finite-difference timedomain (FDTD) simulations with the aim of identifying the dependence of these modes on geometry (length, width), tapering, shape (cylindrical, hexagonal), core-shell versus core-only, and dielectric cores with semiconductor shells. This demonstrates how nanowires (NWs) form excellent optical cavities without the need for top and bottommirrors. However, optically equivalent structures such as hexagonal and cylindrical wires can have very different optoelectronic properties meaning that light management alone does not sufficiently describe the observed enhancement in upward (absorption) and downward transitions (emission) of light inNWs; rather, the electronic transition rates should be considered. We discuss this "rate management" scheme showing its strong dimensional dependence, making a case for photonic integrated circuits (PICs) that can take advantage of the confluence of the desirable optical and electronic properties of these nanostructures.

  19. Selected lactic acid-producing bacterial isolates with the capacity to reduce Salmonella translocation and virulence gene expression in chickens.

    Directory of Open Access Journals (Sweden)

    Xiaojian Yang

    Full Text Available BACKGROUND: Probiotics have been used to control Salmonella colonization/infection in chickens. Yet the mechanisms of probiotic effects are not fully understood. This study has characterized our previously-selected lactic acid-producing bacterial (LAB isolates for controlling Salmonella infection in chickens, particularly the mechanism underlying the control. METHODOLOGY/PRINCIPAL FINDINGS: In vitro studies were conducted to characterize 14 LAB isolates for their tolerance to low pH (2.0 and high bile salt (0.3-1.5% and susceptibility to antibiotics. Three chicken infection trials were subsequently carried out to evaluate four of the isolates for reducing the burden of Salmonella enterica serovar Typhimurium in the broiler cecum. Chicks were gavaged with LAB cultures (10(6-7 CFU/chick or phosphate-buffered saline (PBS at 1 day of age followed by Salmonella challenge (10(4 CFU/chick next day. Samples of cecal digesta, spleen, and liver were examined for Salmonella counts on days 1, 3, or 4 post-challenge. Salmonella in the cecum from Trial 3 was also assessed for the expression of ten virulence genes located in its pathogenicity island-1 (SPI-1. These genes play a role in Salmonella intestinal invasion. Tested LAB isolates (individuals or mixed cultures were unable to lower Salmonella burden in the chicken cecum, but able to attenuate Salmonella infection in the spleen and liver. The LAB treatments also reduced almost all SPI-1 virulence gene expression (9 out of 10 in the chicken cecum, particularly at the low dose. In vitro treatment with the extracellular culture fluid from a LAB culture also down-regulated most SPI-1 virulence gene expression. CONCLUSIONS/SIGNIFICANCE: The possible correlation between attenuation of Salmonella infection in the chicken spleen and liver and reduction of Salmonella SPI-1 virulence gene expression in the chicken cecum by LAB isolates is a new observation. Suppression of Salmonella virulence gene expression in

  20. How do marine bacteria produce light, why are they luminescent, and can we employ bacterial bioluminescence in aquatic biotechnology?

    Directory of Open Access Journals (Sweden)

    Grzegorz Wêgrzyn

    2002-09-01

    Full Text Available Bioluminescence, the phenomenon of light production by living organisms, occurs in forms of life as various as bacteria, fungi and animals. Nevertheless, light-emitting bacteria are the most abundant and widespread of luminescent organisms. Interestingly, most species of such bacteria live in marine environments. In this article, the biochemical mechanism of bacterial luminescence and its genetic regulation are summarized. Although the biochemistry and genetics of light emission by cells have been investigated in detail, the biological role of bacterial luminescence has remained obscure. Here, we discuss recent discoveries that shed new light on this problem. Finally, we provide examples of how bacterial luminescence can be employed in marine biotechnology, especially in the detection of toxic and mutagenic pollution in aquatic environments.

  1. Formation of chiral branched nanowires by the Eshelby Twist.

    Science.gov (United States)

    Zhu, Jia; Peng, Hailin; Marshall, A F; Barnett, D M; Nix, W D; Cui, Yi

    2008-08-01

    Manipulating the morphology of inorganic nanostructures, such as their chirality and branching structure, has been actively pursued as a means of controlling their electrical, optical and mechanical properties. Notable examples of chiral inorganic nanostructures include carbon nanotubes, gold multishell nanowires, mesoporous nanowires and helical nanowires. Branched nanostructures have also been studied and been shown to have interesting properties for energy harvesting and nanoelectronics. Combining both chiral and branching motifs into nanostructures might provide new materials properties. Here we show a chiral branched PbSe nanowire structure, which is formed by a vapour-liquid-solid branching from a central nanowire with an axial screw dislocation. The chirality is caused by the elastic strain of the axial screw dislocation, which produces a corresponding Eshelby Twist in the nanowires. In addition to opening up new opportunities for tailoring the properties of nanomaterials, these chiral branched nanowires also provide a direct visualization of the Eshelby Twist. PMID:18685634

  2. Laser direct synthesis of silicon nanowire field effect transistors

    International Nuclear Information System (INIS)

    We demonstrate a single-step, laser-based technique to fabricate silicon nanowire field effect transistors. Boron-doped silicon nanowires are synthesized using a laser-direct-write chemical vapor deposition process, which can produce nanowires as small as 60 nm, far below the diffraction limit of the laser wavelength of 395 nm. In addition, the method has the advantages of in situ doping, catalyst-free growth, and precise control of nanowire position, orientation, and length. Silicon nanowires are directly fabricated on an insulating surface and ready for subsequent device fabrication without the need for transfer and alignment, thus greatly simplifying device fabrication processes. Schottky barrier nanowire field effect transistors with a back-gate configuration are fabricated from the laser-direct-written Si nanowires and electrically characterized. (paper)

  3. Photoelectrochemistry of Semiconductor Nanowire Arrays

    Energy Technology Data Exchange (ETDEWEB)

    Mallouk, Thomas E; Redwing, Joan M

    2009-11-10

    This project supported research on the growth and photoelectrochemical characterization of semiconductor nanowire arrays, and on the development of catalytic materials for visible light water splitting to produce hydrogen and oxygen. Silicon nanowires were grown in the pores of anodic aluminum oxide films by the vapor-liquid-solid technique and were characterized electrochemically. Because adventitious doping from the membrane led to high dark currents, silicon nanowire arrays were then grown on silicon substrates. The dependence of the dark current and photovoltage on preparation techniques, wire diameter, and defect density was studied for both p-silicon and p-indium phosphide nanowire arrays. The open circuit photovoltage of liquid junction cells increased with increasing wire diameter, reaching 350 mV for micron-diameter silicon wires. Liquid junction and radial p-n junction solar cells were fabricated from silicon nano- and microwire arrays and tested. Iridium oxide cluster catalysts stabilized by bidentate malonate and succinate ligands were also made and studied for the water oxidation reaction. Highlights of this project included the first papers on silicon and indium phosphide nanowire solar cells, and a new procedure for making ligand-stabilized water oxidation catalysts that can be covalently linked to molecular photosensitizers or electrode surfaces.

  4. How Copper Nanowires Grow and How To Control Their Properties.

    Science.gov (United States)

    Ye, Shengrong; Stewart, Ian E; Chen, Zuofeng; Li, Bo; Rathmell, Aaron R; Wiley, Benjamin J

    2016-03-15

    Scalable, solution-phase nanostructure synthesis has the promise to produce a wide variety of nanomaterials with novel properties at a cost that is low enough for these materials to be used to solve problems. For example, solution-synthesized metal nanowires are now being used to make low cost, flexible transparent electrodes in touch screens, organic light-emitting diodes (OLEDs), and solar cells. There has been a tremendous increase in the number of solution-phase syntheses that enable control over the assembly of atoms into nanowires in the last 15 years, but proposed mechanisms for nanowire formation are usually qualitative, and for many syntheses there is little consensus as to how nanowires form. It is often not clear what species is adding to a nanowire growing in solution or what mechanistic step limits its rate of growth. A deeper understanding of nanowire growth is important for efficiently directing the development of nanowire synthesis toward producing a wide variety of nanostructure morphologies for structure-property studies or producing precisely defined nanostructures for a specific application. This Account reviews our progress over the last five years toward understanding how copper nanowires form in solution, how to direct their growth into nanowires with dimensions ideally suited for use in transparent conducting films, and how to use copper nanowires as a template to grow core-shell nanowires. The key advance enabling a better understanding of copper nanowire growth is the first real-time visualization of nanowire growth in solution, enabling the acquisition of nanowire growth kinetics. By measuring the growth rate of individual nanowires as a function of concentration of the reactants and temperature, we show that a growing copper nanowire can be thought of as a microelectrode that is charged with electrons by hydrazine and grows through the diffusion-limited addition of Cu(OH)2(-). This deeper mechanistic understanding, coupled to an

  5. Metabolism of DMSP, DMS and DMSO by the cultivable bacterial community associated with the DMSP-producing dinoflagellate Scrippsiella trochoidea

    Digital Repository Service at National Institute of Oceanography (India)

    Hatton, A.D.; Shenoy, D.M.; Hart, M.C.; Mogg, A.; Green, D.H.

    Howard EC, Henriksen JR, Buchan A, Reisch CR, Burgmann H, Welsh R, Ye W, Gonzalez JM, Mace K, Joye SB, Kiene RP, Whitman WB, Moran MA (2006) Bacterial taxa that limit sulfur flux from the ocean. Science 314(5799): 649–652 Howard EC, Sun S, Biers EJ...

  6. Isolation and Identification of a New Tetrodotoxin-Producing Bacterial Species, Raoultella terrigena, from Hong Kong Marine Puffer Fish Takifugu niphobles

    OpenAIRE

    Fred Wang-Fat Lee; Peter Hoi-Fu Yu; Vincent Chung-Him Yu; Kin-Chung Ho

    2011-01-01

    Puffer fish, Takifugu niphobles, collected from the Hong Kong coastal waters were screened for tetrodotoxin-producing bacteria. A Gram-negative, non-acid-fast, non-sporing and rod shaped bacterial strain (designated as gutB01) was isolated from the intestine of the puffer fish and was shown to produce tetrodotoxin (TTX). Based on the Microbial Identification (MIDI) and 16S-23S rDNA internal transcribed spacer (ITS) phylogenetic analysis, the strain was identified as Raoultella terrigena. The ...

  7. Nanowire Optoelectronics

    Directory of Open Access Journals (Sweden)

    Wang Zhihuan

    2015-12-01

    Full Text Available Semiconductor nanowires have been used in a variety of passive and active optoelectronic devices including waveguides, photodetectors, solar cells, light-emitting diodes (LEDs, lasers, sensors, and optical antennas. We review the optical properties of these nanowires in terms of absorption, guiding, and radiation of light, which may be termed light management. Analysis of the interaction of light with long cylindrical/hexagonal structures with subwavelength diameters identifies radial resonant modes, such as Leaky Mode Resonances, or Whispering Gallery modes. The two-dimensional treatment should incorporate axial variations in “volumetric modes,”which have so far been presented in terms of Fabry–Perot (FP, and helical resonance modes. We report on finite-difference timedomain (FDTD simulations with the aim of identifying the dependence of these modes on geometry (length, width, tapering, shape (cylindrical, hexagonal, core–shell versus core-only, and dielectric cores with semiconductor shells. This demonstrates how nanowires (NWs form excellent optical cavities without the need for top and bottommirrors. However, optically equivalent structures such as hexagonal and cylindrical wires can have very different optoelectronic properties meaning that light management alone does not sufficiently describe the observed enhancement in upward (absorption and downward transitions (emission of light inNWs; rather, the electronic transition rates should be considered. We discuss this “rate management” scheme showing its strong dimensional dependence, making a case for photonic integrated circuits (PICs that can take advantage of the confluence of the desirable optical and electronic properties of these nanostructures.

  8. Perspectives of single cast nanowires technology

    International Nuclear Information System (INIS)

    The paper is dedicated to production potential of glass-coated cast nanowire with metal-, semimetal- and semiconductor-based cores by means of Taylor-Ulitovsky method. Criteria of melted core-formative material penetration into a drawing capillary were analyzed. Theoretical preconditions of the reduction of cast microwire diameter up to nano-dimensions of core are reviewed and an improved method of cast nanowire manufacturing is proposed. Correctness of conclusions was experimentally proved and laboratory samples of micro- and nano-wires with core diameter of about 200-300 nanometers were produced, even in case of materials with poor adhesion.

  9. Increasing the efficiency of polymer solar cells by silicon nanowires

    International Nuclear Information System (INIS)

    Silicon nanowires have been introduced into P3HT:[60]PCBM solar cells, resulting in hybrid organic/inorganic solar cells. A cell efficiency of 4.2% has been achieved, which is a relative improvement of 10% compared to a reference cell produced without nanowires. This increase in cell performance is possibly due to an enhancement of the electron transport properties imposed by the silicon nanowires. In this paper, we present a novel approach for introducing the nanowires by mixing them into the polymer blend and subsequently coating the polymer/nanowire blend onto a substrate. This new onset may represent a viable pathway to producing nanowire-enhanced polymer solar cells in a reel to reel process.

  10. Electrical properties of single CdTe nanowires

    OpenAIRE

    Elena Matei; Camelia Florica; Andreea Costas; María Eugenia Toimil-Molares; Ionut Enculescu

    2015-01-01

    Ion track, nanoporous membranes were employed as templates for the preparation of CdTe nanowires. For this purpose, electrochemical deposition from a bath containing Cd and Te ions was employed. This process leads to high aspect ratio CdTe nanowires, which were harvested and placed on a substrate with lithographically patterned, interdigitated electrodes. Focused ion beam-induced metallization was used to produce individual nanowires with electrical contacts and electrical measurements were p...

  11. Vertical nanowire architectures

    DEFF Research Database (Denmark)

    Vlad, A.; Mátéfl-Tempfli, M.; Piraux, L.;

    2010-01-01

    Nanowires and statistics: A statistical process for reading ultradense arrays of nanostructured materials is presented (see image). The experimental realization is achieved through selective nanowire growth using porous alumina templates. The statistical patterning approach is found to provide ri...

  12. Magnetic and superconducting nanowires

    DEFF Research Database (Denmark)

    Piraux, L.; Encinas, A.; Vila, L.;

    2005-01-01

    magnetic and superconducting nanowires. Using different approaches entailing measurements on both single wires and arrays, numerous interesting physical properties have been identified in relation to the nanoscopic dimensions of these materials. Finally, various novel applications of the nanowires are also...

  13. Inquisition of Microcystis aeruginosa and Synechocystis nanowires: characterization and modelling.

    Science.gov (United States)

    Sure, Sandeep; Torriero, Angel A J; Gaur, Aditya; Li, Lu Hua; Chen, Ying; Tripathi, Chandrakant; Adholeya, Alok; Ackland, M Leigh; Kochar, Mandira

    2015-11-01

    Identification of extracellular conductive pilus-like structures (PLS) i.e. microbial nanowires has spurred great interest among scientists due to their potential applications in the fields of biogeochemistry, bioelectronics, bioremediation etc. Using conductive atomic force microscopy, we identified microbial nanowires in Microcystis aeruginosa PCC 7806 which is an aerobic, photosynthetic microorganism. We also confirmed the earlier finding that Synechocystis sp. PCC 6803 produces microbial nanowires. In contrast to the use of highly instrumented continuous flow reactors for Synechocystis reported earlier, we identified simple and optimum culture conditions which allow increased production of nanowires in both test cyanobacteria. Production of these nanowires in Synechocystis and Microcystis were found to be sensitive to the availability of carbon source and light intensity. These structures seem to be proteinaceous in nature and their diameter was found to be 4.5-7 and 8.5-11 nm in Synechocystis and M. aeruginosa, respectively. Characterization of Synechocystis nanowires by transmission electron microscopy and biochemical techniques confirmed that they are type IV pili (TFP) while nanowires in M. aeruginosa were found to be similar to an unnamed protein (GenBank : CAO90693.1). Modelling studies of the Synechocystis TFP subunit i.e. PilA1 indicated that strategically placed aromatic amino acids may be involved in electron transfer through these nanowires. This study identifies PLS from Microcystis which can act as nanowires and supports the earlier hypothesis that microbial nanowires are widespread in nature and play diverse roles. PMID:26319534

  14. A simple synthesis method to produce metal oxide loaded carbon paper using bacterial cellulose gel and characterization of its electrochemical behavior in an aqueous electrolyte

    Science.gov (United States)

    Miyajima, Naoya; Jinguji, Ken; Matsumura, Taiyu; Matsubara, Toshihiro; Sakane, Hideto; Akatsu, Takashi; Tanaike, Osamu

    2016-04-01

    A simple synthetic chemical process to produce metal oxide loaded carbon papers was developed using bacterial cellulose gel, which consisted of nanometer-sized fibrous cellulose and water. Metal ions were successfully impregnated into the gel via aqueous solution media before drying and carbonization methods resulting in metal oxide contents that were easy to control through variations in the concentration of aqueous solutions. The papers loaded by molybdenum oxides were characterized as pseudocapacitor electrodes preliminary, and the large redox capacitance of the oxides was followed by a conductive fibrous carbon substrate, suggesting that a binder and carbon black additive-free electrode consisting of metal oxides and carbon paper was formed.

  15. Properties of a new gasoline oxygenate blend component: 3-Hydroxybutyrate methyl ester produced from bacterial poly-3-hydroxybutyrate

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shen Yu.; Wang, Zhen; Liu, Ming Ming; Zhang, Xiao Jun [Multidisciplinary Research Center, Shantou University, Shantou 515063, Guangdong (China); Xu, Yu. [Oilcare Oil Test Laboratory of China National Analytical Center, 6th Floor, Building 34, No. 100, Xian Lie Zhong Road, Guangzhou 510000 (China); Chen, Guo-Qiang [Dept Biological Sciences and Biotechnology, School of Life Science, Tsinghua University, Beijing 100084 (China)

    2010-08-15

    3-Hydroxybutyrate methyl ester (HBME) was prepared from hydrolysis of bacterial poly-3-hydroxybutyrate (PHB) using methanol as an esterification agent in the presence of sulfuric acid. Physicochemical and fuel related properties of HBME were studied for the possibility of using HBME as a gasoline additive. When HBME was blended with 97 gasoline in volume ratios of 5%, 8.5%, 10%, 15% and 20%, respectively, it was found that HBME had similar or better properties as a fuel additive compared with ethanol in terms of oxygen content, dynamic viscosity, flash point and boiling point. The blending of HBME and gasoline showed only little difference compared with the 97 gasoline in terms of octane number (RON) and distillation ranges, especially for the HBME 8.5% and 10% blends, which demonstrated an over 93% combustion heat of gasoline with less than 5% reduction in RON. (author)

  16. Electrical properties of single CdTe nanowires

    Directory of Open Access Journals (Sweden)

    Elena Matei

    2015-02-01

    Full Text Available Ion track, nanoporous membranes were employed as templates for the preparation of CdTe nanowires. For this purpose, electrochemical deposition from a bath containing Cd and Te ions was employed. This process leads to high aspect ratio CdTe nanowires, which were harvested and placed on a substrate with lithographically patterned, interdigitated electrodes. Focused ion beam-induced metallization was used to produce individual nanowires with electrical contacts and electrical measurements were performed on these individual nanowires. The influence of a bottom gate was investigated and it was found that surface passivation leads to improved transport properties.

  17. A high-throughput approach to identify genomic variants of bacterial metabolite producers at the single-cell level.

    Science.gov (United States)

    Binder, Stephan; Schendzielorz, Georg; Stäbler, Norma; Krumbach, Karin; Hoffmann, Kristina; Bott, Michael; Eggeling, Lothar

    2012-01-01

    We present a novel method for visualizing intracellular metabolite concentrations within single cells of Escherichia coli and Corynebacterium glutamicum that expedites the screening process of producers. It is based on transcription factors and we used it to isolate new L-lysine producing mutants of C. glutamicum from a large library of mutagenized cells using fluorescence-activated cell sorting (FACS). This high-throughput method fills the gap between existing high-throughput methods for mutant generation and genome analysis. The technology has diverse applications in the analysis of producer populations and screening of mutant libraries that carry mutations in plasmids or genomes. PMID:22640862

  18. A high-throughput approach to identify genomic variants of bacterial metabolite producers at the single-cell level

    OpenAIRE

    Binder, Stephan; Schendzielorz, Georg; Stäbler, Norma; Krumbach, Karin; Hoffmann, Kristina; Bott, Michael; Eggeling, Lothar

    2012-01-01

    We present a novel method for visualizing intracellular metabolite concentrations within single cells of Escherichia coli and Corynebacterium glutamicum that expedites the screening process of producers. It is based on transcription factors and we used it to isolate new L-lysine producing mutants of C. glutamicum from a large library of mutagenized cells using fluorescence-activated cell sorting (FACS). This high-throughput method fills the gap between existing high-throughput methods for mut...

  19. Stability of Organic Nanowires

    DEFF Research Database (Denmark)

    Balzer, F.; Schiek, M.; Wallmann, I.;

    2011-01-01

    The morphological stability of organic nanowires over time and under thermal load is of major importance for their use in any device. In this study the growth and stability of organic nanowires from a naphthyl end-capped thiophene grown by organic molecular beam deposition is investigated via...... atomic force microscopy (AFM). Aging experiments under ambient conditions already show substantial morphological changes. Nanoscopic organic clusters, which initially coexist with the nanowires, vanish within hours. Thermal annealing of nanowire samples leads to even more pronounced morphology changes......, such as a strong decrease in nanowire number density, a strong increase in nanowire height, and the formation of new types of crystallites. This happens even before sublimation of organic material starts. These experiments also shine new light on the formation process of the nanowires....

  20. Endocytosis-inducer adhesins produced by enteropathogenic serogroups of Escherichia coli participate on bacterial attachment to infant enterocytes

    Directory of Open Access Journals (Sweden)

    João Ramos Costa Andrade

    1987-03-01

    Full Text Available Enteropathogenic E. coli (EPEC infection of Hep-2 cells preoceeds through bacterial attachment to cell surface and internalization of adhered bacteria. EPEC attachment is a prerequisite for cell infection and is mediated by adhesins that recognize carbohydrate-containing receptors on cell membrane. Such endocytosis-inducer adhesins (EIA also promote EPEC binding to infant enterocytes, suggesting that EIA may have an important role on EPEC gastroenteritis.A infecção de células Hep-2 por E. coli enteropatogênicas (ECEP implica na aderência bacteriana e posterior interiorização dos microrganismos aderidos por um mecanismo de endocitose. A aderência das ECEP é pré-requisito para a infecção e é mediada por adesinas que reconhecem receptores inibidos por certas oses na membrana celular. Tais "adesinas indutoras da endocitose" (AIE também promovem a ligação bacteriana a enterócitos obtidos do intestino delgado de lactente, sugerindo que as AIE possam desempenhar algum papel nas diarréias causadas por ECEP.

  1. Nitrogen and energy balance in growing mink (Mustela vison) fed different levels of bacterial protein meal produced with natural gas

    DEFF Research Database (Denmark)

    Hellwing, Anne Louise Frydendahl; Tauson, Anne-Helene; Ahlstrøm, Øystein;

    2005-01-01

    The objective of this study was to estimate the effect of increasing the dietary content of bacterial protein meal (BPM) on energy and protein metabolism in growing mink kits. Sixteen male mink kits of the standard brown genotype were randomly fed one of four diets: A control (Diet III) and 60......% (Diet IV) of the digested nitrogen (DN) was replaced with BPM. Nitrogen balance and respiration experiments (indirect calorimetry) were carried out when the animals were approximately 9.5, 14.5, 17.5, 23.5 and 28.5 weeks of age. The apparent digestibility of crude protein and energy decreased...... significantly with increasing dietary BPM. The retained nitrogen was 0.45, 0.54, 0.52 and 0.40 g/kg0,75 on Diets I, II, III and IV, respectively, the observed differences between diets being non-significant (p=0.06). Heat production (HE) was between 645 and 665 kJ/kg0.75 on all diets (p=0.78). retained energy...

  2. Construction and evaluation of an exopolysaccharide-producing engineered bacterial strain by protoplast fusion for microbial enhanced oil recovery.

    Science.gov (United States)

    Sun, Shanshan; Luo, Yijing; Cao, Siyuan; Li, Wenhong; Zhang, Zhongzhi; Jiang, Lingxi; Dong, Hanping; Yu, Li; Wu, Wei-Min

    2013-09-01

    Enterobacter cloacae strain JD, which produces water-insoluble biopolymers at optimal temperature of 30°C, and a thermophilic Geobacillus strain were used to construct an engineered strain for exopolysaccharide production at high temperatures by protoplast fusion. The obtained fusant strain ZR3 produced exopolysaccharides at up to 45°C with optimal growth temperature at 35°C. The fusant produced exopolysaccharides of approximately 7.5 g/L or more at pH between 7.0 and 9.0. The feasibility of the enhancement of crude oil recovery with the fusant was tested in a sand-packed column at 40°C. The results demonstrated that bioaugmentation of the fusant was promising approach for MEOR. Mass growth of the fusant was confirmed in fermentor tests. PMID:23856587

  3. Enzymes produced by halotolerant spore-forming gram-positive bacterial strains isolated from a resting habitat (Restinga de Jurubatiba) in Rio de Janeiro, Brazil: focus on proteases.

    Science.gov (United States)

    D Santos, Anderson Fragoso; Pacheco, Clarissa Almeida; Valle, Roberta D Santos; Seldin, Lucy; D Santos, André Luis Souza

    2014-12-01

    The screening for hydrolases-producing, halotolerant, and spore-forming gram-positive bacteria from the root, rhizosphere, and non-rhizosphere soil of Blutaparon portulacoides, a plant found in the Restinga de Jurubatiba located at the northern region of Rio de Janeiro State, Brazil, resulted in the isolation of 22 strains. These strains were identified as Halobacillus blutaparonensis (n = 2), Oceanobacillus picturae (n = 5), and Oceanobacillus iheyensis (n = 15), and all showed the ability to produce different extracellular enzymes. A total of 20 isolates (90.9 %) showed activity for protease, 5 (22.7 %) for phytase, 3 (13.6 %) for cellulase, and 2 (9.1 %) for amylase. Some bacterial strains were capable of producing three (13.6 %) or two (9.1 %) distinct hydrolytic enzymes. However, no bacterial strain with ability to produce esterase and DNase was observed. The isolate designated M9, belonging to the species H. blutaparonensis, was the best producer of protease and also yielded amylase and phytase. This strain was chosen for further studies regarding its protease activity. The M9 strain produced similar amounts of protease when grown either without or with different NaCl concentrations (from 0.5 to 10 %). A simple inspection of the cell-free culture supernatant by gelatin-sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed the presence of three major alkaline proteases of 40, 50, and 70 kDa, which were fully inhibited by phenylmethylsulfonyl fluoride (PMSF) and tosyl-L-phenylalanine chloromethyl ketone (TPCK) (two classical serine protease inhibitors). The secreted proteases were detected in a wide range of temperature (from 4 to 45 °C) and their hydrolytic activities were stimulated by NaCl (up to 10 %). The serine proteases produced by the M9 strain cleaved gelatin, casein, albumin, and hemoglobin, however, in different extensions. Collectively, these results suggest the potential use of the M9 strain in biotechnological

  4. Nanotubes and nanowires

    Indian Academy of Sciences (India)

    C N R Rao; A Govindaraj

    2001-10-01

    Synthesis and characterization of nanotubes and nanowires constitute an important part of nanoscience since these materials are essential bui lding units for several devices. We have prepared aligned carbon nanotube bundles and Y-junction nanotubes by the pyrolysis of appropriate organic precursors. The aligned bundles are useful for field emission display while the Y-junction nanotubes are likely to be useful as nanochips since they exhibit diode properties at the junction. By making use of carbon nanotubes, nanowires of metals, metal oxides and GaN have be en obt a ined. Both the oxide and GaN nanowires are single crystalline. Gold nanowires exhibit plasmon bands varying markedly with the aspect ratio. GaN nanowires show excellent photoluminescence characteristics. It has been possible to synthesise nanotubes and nanowires of metal chalcogenides by employing different strategies.

  5. Growh performance, nitrogen balance and urinary purine derivatives in growing-furring mink (Mustela vison) fed bacterial protein produced from natural gas

    DEFF Research Database (Denmark)

    Ahlstrøm, Ø.; Tauson, Anne-Helene; Hellwing, Anne Louise Frydendahl;

    2006-01-01

    A bacterial protein meal (BPM), containing 70% crude protein and produced on natural gas, was evaluated versus fish meal as protein source for mink in the growing-furring period (June 29-November 26). BPM, rich in nucleic acids, accounted for 0 (control), 20 and 40% of dietary crude protein...... corresponding to 0,4 and 8% of the wet diets, respectively. Each diet was given to 48 animals, 24 males and 24 females. The inclusion of BPM tended to reduce feed intake and body weight gain during the first half of the experimental period, but this was compensated for during the last part of the experiment......, except for males on the 8% BPM diet. Balance experiments carried out with 18 and 28 weeks old males, revealed similar digestibility of main nutrients except for fat that were reduced with BPM inclusion. N-retentions were similar for the dietary groups. Daily excretion of urine was lower with the 8% BPM...

  6. Optical fibre nanowire devices

    OpenAIRE

    Xu, Fei

    2008-01-01

    The Optical Fibre Nanowire (OFN) is a potential building block in future micro- and nano-photonic device since it offers a number of unique optical and mechanical properties. In this thesis, the background and fundamental features of nanowires are introduced; the theory, design and demonstration of novel nanowire devices are discussed. At first, a short adiabatic taper tip is manufactured, and it is used as optical tweezers for trapping 1?m microspheres. Then, the most important devic...

  7. Bacterial lipases

    NARCIS (Netherlands)

    Jaeger, Karl-Erich; Ransac, Stéphane; Dijkstra, Bauke W.; Colson, Charles; Heuvel, Margreet van; Misset, Onno

    1994-01-01

    Many different bacterial species produce lipases which hydrolyze esters of glycerol with preferably long-chain fatty acids. They act at the interface generated by a hydrophobic lipid substrate in a hydrophilic aqueous medium. A characteristic property of lipases is called interfacial activation, mea

  8. Growth of Gold-assisted Gallium Arsenide Nanowires on Silicon Substrates via Molecular Beam Epitaxy

    Directory of Open Access Journals (Sweden)

    Ramon M. delos Santos

    2008-06-01

    Full Text Available Gallium arsenide nanowires were grown on silicon (100 substrates by what is called the vapor-liquid-solid (VLS growth mechanism using a molecular beam epitaxy (MBE system. Good quality nanowires with surface density of approximately 108 nanowires per square centimeter were produced by utilizing gold nanoparticles, with density of 1011 nanoparticles per square centimeter, as catalysts for nanowire growth. X-ray diffraction measurements, scanning electron microscopy, transmission electron microscopy and Raman spectroscopy revealed that the nanowires are epitaxially grown on the silicon substrates, are oriented along the [111] direction and have cubic zincblende structure.

  9. Bacterial carbonatogenesis

    International Nuclear Information System (INIS)

    Several series of experiments in the laboratory as well as in natural conditions teach that the production of carbonate particles by heterotrophic bacteria follows different ways. The 'passive' carbonatogenesis is generated by modifications of the medium that lead to the accumulation of carbonate and bicarbonate ions and to the precipitation of solid particles. The 'active' carbonatogenesis is independent of the metabolic pathways. The carbonate particles are produced by ionic exchanges through the cell membrane following still poorly known mechanisms. Carbonatogenesis appears to be the response of heterotrophic bacterial communities to an enrichment of the milieu in organic matter. The active carbonatogenesis seems to start first. It is followed by the passive one which induces the growth of initially produced particles. The yield of heterotrophic bacterial carbonatogenesis and the amounts of solid carbonates production by bacteria are potentially very high as compared to autotrophic or chemical sedimentation from marine, paralic or continental waters. Furthermore, the bacterial processes are environmentally very ubiquitous; they just require organic matter enrichment. Thus, apart from purely evaporite and autotrophic ones, all Ca and/or Mg carbonates must be considered as from heterotrophic bacterial origin. By the way, the carbon of carbonates comes from primary organic matter. Such considerations ask questions about some interpretations from isotopic data on carbonates. Finally, bacterial heterotrophic carbonatogenesis appears as a fundamental phase in the relationships between atmosphere and lithosphere and in the geo-biological evolution of Earth. (author)

  10. Oxygen and sulfur isotope systematics of sulfate produced during abiotic and bacterial oxidation of sphalerite and elemental sulfur

    Science.gov (United States)

    Balci, N.; Mayer, B.; Shanks, Wayne C.; Mandernack, K.W.

    2012-01-01

    Studies of metal sulfide oxidation in acid mine drainage (AMD) systems have primarily focused on pyrite oxidation, although acid soluble sulfides (e.g., ZnS) are predominantly responsible for the release of toxic metals. We conducted a series of biological and abiotic laboratory oxidation experiments with pure and Fe-bearing sphalerite (ZnS & Zn 0.88Fe 0.12S), respectively, in order to better understand the effects of sulfide mineralogy and associated biogeochemical controls of oxidation on the resultant ?? 34S and ?? 18O values of the sulfate produced. The minerals were incubated in the presence and absence of Acidithiobacillus ferrooxidans at an initial solution pH of 3 and with water of varying ?? 18O values to determine the relative contributions of H 2O-derived and O 2-derived oxygen in the newly formed sulfate. Experiments were conducted under aerobic and anaerobic conditions using O 2 and Fe(III) aq as the oxidants, respectively. Aerobic incubations with A. ferrooxidans, and S o as the sole energy source were also conducted. The ??34SSO4 values from both the biological and abiotic oxidation of ZnS and ZnS Fe by Fe(III) aq produced sulfur isotope fractionations (??34SSO4-ZnS) of up to -2.6???, suggesting the accumulation of sulfur intermediates during incomplete oxidation of the sulfide. No significant sulfur isotope fractionation was observed from any of the aerobic experiments. Negative sulfur isotope enrichment factors (??34SSO4-ZnS) in AMD systems could reflect anaerobic, rather than aerobic pathways of oxidation. During the biological and abiotic oxidation of ZnS and ZnS Fe by Fe(III) aq all of the sulfate oxygen was derived from water, with measured ?? 18OSO 4-H 2O values of 8.2??0.2??? and 7.5??0.1???, respectively. Also, during the aerobic oxidation of ZnS Fe and S o by A. ferrooxidans, all of the sulfate oxygen was derived from water with similar measured ?? 18OSO 4-H 2O values of 8.1??0.1??? and 8.3??0.3???, respectively. During biological oxidation

  11. Characterisation of the bacterial microbiota of the vagina of dairy cows and isolation of pediocin-producing Pediococcus acidilactici

    Directory of Open Access Journals (Sweden)

    Wang Yvonne

    2013-01-01

    Full Text Available Abstract Background Uterine infections in dairy cows lower profitability of dairy operations. Infections of the reproductive tract are related to the overgrowth of pathogenic bacteria during the first three weeks after parturition. However, alterations in the vaginal microbiota composition in the first weeks after parturition remain poorly documented. Results In this study, bacteria isolated from the vagina of healthy pregnant, and infected postpartum cows were characterised by random amplification of polymorphic DNA (RAPD analysis and partial 16S ribosomal RNA (rDNA gene sequencing. Populations of bacilli and lactic acid bacteria of the genera Enterococcus, Lactobacillus, and Pediococcus were present in both healthy and infected cows. Infected cows had a significant increase in the vaginal enteric bacteria population which consisted mainly of Escherichia coli. Three E. coli isolates harboured the gene coding for Shiga-like-toxin (SLT I or II. Several isolates of the Pediococcus acidilactici were found to produce the bacteriocin pediocin AcH/PA-1. Quantitative PCR analyses of vaginal mucus samples collected from ten metritic cows before and after parturition confirmed the presence of the Lactobacillus group (Lactobacillus spp., Pediococcus spp., Leuconostoc spp., and Weissella spp.; Enterobacteriaceae, E. coli, and bacilli. The presence of the pediocin AcH/PA-1 structural gene and SLT genes were also confirmed with qPCR. Conclusions In conclusion, overgrowth of pathogenic bacteria, particularly E. coli, after parturition likely contributes to the development of metritis. Our microbiota analysis extends the information related to the composition of commensal bacteria in the bovine female reproductive tract and may facilitate the development of novel intervention strategies for prevention of uterine infections in dairy cows.

  12. Effects of volatile organic compounds produced by Bacillus amyloliquefaciens on the growth and virulence traits of tomato bacterial wilt pathogen Ralstonia solanacearum.

    Science.gov (United States)

    Raza, Waseem; Wang, Jichen; Wu, Yuncheng; Ling, Ning; Wei, Zhong; Huang, Qiwei; Shen, Qirong

    2016-09-01

    The production of volatile organic compounds (VOCs) by microbes is an important characteristic for their selection as biocontrol agents against plant pathogens. In this study, we identified the VOCs produced by the biocontrol strain Bacillus amyloliquefaciens T-5 and evaluated their impact on the growth and virulence traits of tomato bacterial wilt pathogen Ralstonia solanacearum. The results showed that the VOCs of strain T-5 significantly inhibited the growth of R. solanacearum in agar medium and in soil. In addition, VOCs significantly inhibited the motility traits, root colonization, biofilm formation, and production of antioxidant enzymes and exopolysaccharides by R. solanacearum. However, no effect of VOCs on the production of hydrolytic enzymes by R. solanacearum was observed. The strain T-5 produced VOCs, including benzenes, ketones, aldehydes, alkanes, acids, and one furan and naphthalene compound; among those, 13 VOCs showed 1-10 % antibacterial activity against R. solanacearum in their produced amounts by T-5; however, the consortium of all VOCs produced on agar medium, in sterilized soil, and in natural soil showed 75, 62, and 85 % growth inhibition of R. solanacearum, respectively. The real-time PCR analysis further confirmed the results when the expression of different virulence- and metabolism-related genes in R. solanacearum cells was decreased after exposure to the VOCs of strain T-5. The results of this study clearly revealed the significance of VOCs in the control of plant pathogens. This information would help to better comprehend the microbial interactions mediated by VOCs in nature and to develop safer strategies to control plant disease. PMID:27183998

  13. Development of methods for orderly growth of nanowires

    Science.gov (United States)

    Reznik, R. R.; Kotlyar, K. P.; Khrebtov, A. I.; Samsonenko, Yu B.; Soshnikov, I. P.; Dyakonov, V.; Zadiranov, U. M.; Tankelevskaya, E. M.; Kudryashov, D. A.; Shevchuk, D. S.; Cirlin, G. E.

    2015-12-01

    Method of manufacturing substrates for self-catalyst/free-catalyst ordered growth of the nanowires has been developed. Experiments show the possibility of autocatalytic growth of ordered GaAs NWs on the substrates produced during the research.

  14. A bacterial symbiont is converted from an inedible producer of beneficial molecules into food by a single mutation in the gacA gene.

    Science.gov (United States)

    Stallforth, Pierre; Brock, Debra A; Cantley, Alexandra M; Tian, Xiangjun; Queller, David C; Strassmann, Joan E; Clardy, Jon

    2013-09-01

    Stable multipartite mutualistic associations require that all partners benefit. We show that a single mutational step is sufficient to turn a symbiotic bacterium from an inedible but host-beneficial secondary metabolite producer into a host food source. The bacteria's host is a "farmer" clone of the social amoeba Dictyostelium discoideum that carries and disperses bacteria during its spore stage. Associated with the farmer are two strains of Pseudomonas fluorescens, only one of which serves as a food source. The other strain produces diffusible small molecules: pyrrolnitrin, a known antifungal agent, and a chromene that potently enhances the farmer's spore production and depresses a nonfarmer's spore production. Genome sequence and phylogenetic analyses identify a derived point mutation in the food strain that generates a premature stop codon in a global activator (gacA), encoding the response regulator of a two-component regulatory system. Generation of a knockout mutant of this regulatory gene in the nonfood bacterial strain altered its secondary metabolite profile to match that of the food strain, and also, independently, converted it into a food source. These results suggest that a single mutation in an inedible ancestral strain that served a protective role converted it to a "domesticated" food source. PMID:23898207

  15. SiC nanowires synthesized from graphene and silicon vapors

    Science.gov (United States)

    Weichenpei, Luo; Gong-yi, Li; Zengyong, Chu; Tianjiao, Hu; Xiaodong, Li; Xuefei, Zhang

    2016-04-01

    The preparation of silicon carbide (SiC) nanowires is basically important for its potential applications in nanodevices, nanocomposites, etc. In the present work, a simple route was reported to synthesize SiC nanowires by heating commercial graphene with silicon vapors and no catalyst. Characterization by scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, electron energy scattering, X-ray diffraction, and Raman dispersive spectrum demonstrates the products are composed of β-SiC crystal. The SiC nanowires have the average diameter of about 50 nm and length of tens of micrometers. The vapor-solid mechanism was employed to interpret the SiC nanowires growth. Gaseous SiO which was produced by the reaction of Si powders with its surface oxidation reacted with the solid graphene to form SiC crystal nuclei. And SiC crystal nuclei would act as active sites for further growing into nanowires.

  16. EFSA Panel on Biological Hazards (BIOHAZ); Scientific Opinion on the public health risks of bacterial strains producing extended-spectrum β-lactamases and/or AmpC β-lactamases in food and food-producing animals

    DEFF Research Database (Denmark)

    Hald, Tine; Baggesen, Dorte Lau

    The potential contribution of food-producing animals or foods to public health risks by ESBL and/or AmpC-producing bacteria is related to specific plasmid-mediated ESBL and/or AmpC genes encoded by a number of organisms. The predominant ESBL families encountered are CTX-M, TEM, and SHV; the...... predominant AmpC-family is CMY. The most common genes associated with this resistance in animals are blaCTX-M-1 (the most commonly identified ESBL), and blaCTX-M-14, followed by blaTEM-52 and blaSHV-12. Among the genes encoding AmpC-type β-lactamases, blaCMY-2 is the most common.The bacterial species most...... commonly identified with these genes are Escherichia coli and non-typhoidal Salmonella. ESBL/AmpC transmission is mainly driven by integrons, insertion sequences, transposons and plasmids, some of which are homologous in isolates from both food-production animals and humans. Cefotaxime is used as the drug...

  17. Nanowires for energy generation

    International Nuclear Information System (INIS)

    As a result of their morphology, nanowires bring new properties and the promise of performance for a range of electronic devices. This review looks into the properties of nanowires and the multiple ways in which they have been exploited for energy generation, from photovoltaics to piezoelectric generators. (paper)

  18. Nanowire Photovoltaic Devices

    Science.gov (United States)

    Forbes, David

    2015-01-01

    Firefly Technologies, in collaboration with the Rochester Institute of Technology and the University of Wisconsin-Madison, developed synthesis methods for highly strained nanowires. Two synthesis routes resulted in successful nanowire epitaxy: direct nucleation and growth on the substrate and a novel selective-epitaxy route based on nanolithography using diblock copolymers. The indium-arsenide (InAs) nanowires are implemented in situ within the epitaxy environment-a significant innovation relative to conventional semiconductor nanowire generation using ex situ gold nanoparticles. The introduction of these nanoscale features may enable an intermediate band solar cell while simultaneously increasing the effective absorption volume that can otherwise limit short-circuit current generated by thin quantized layers. The use of nanowires for photovoltaics decouples the absorption process from the current extraction process by virtue of the high aspect ratio. While no functional solar cells resulted from this effort, considerable fundamental understanding of the nanowire epitaxy kinetics and nanopatterning process was developed. This approach could, in principle, be an enabling technology for heterointegration of dissimilar materials. The technology also is applicable to virtual substrates. Incorporating nanowires onto a recrystallized germanium/metal foil substrate would potentially solve the problem of grain boundary shunting of generated carriers by restricting the cross-sectional area of the nanowire (tens of nanometers in diameter) to sizes smaller than the recrystallized grains (0.5 to 1 micron(exp 2).

  19. Metallic nanowire networks

    Science.gov (United States)

    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.

  20. Recent Advances in Directed Assembly of Nanowires or Nanotub es

    Institute of Scientific and Technical Information of China (English)

    Mei Liu; Zhizheng Wu; Woon Ming Lau; Jun Yang

    2012-01-01

    Nanowires and nanotubes of diverse material compositions, properties and/or functions have been produced or fabricated through various bottom-up or top-down approaches. These nanowires or nanotubes have also been utilized as potential building blocks for functional nanodevices. The key for the integration of those nanowire or nanotube based devices is to assemble these one dimensional nanomaterials to specific locations using techniques that are highly controllable and scalable. Ideally such techniques should enable assembly of highly uniform nanowire/nanotube arrays with precise control of density, location, dimension or even ma-terial types of nanowires/nanotubes. Numerous assembly techniques are being developed that can quickly align and assemble large quantities of one type or multiple types of nanowires through parallel processes, in-cluding flow-assisted alignment, Langmuir-Blodgett assembly, bubble-blown technique, electric/magnetic- field directed assembly, contact/roll printing, knocking-down, etc.. With these assembling techniques, applications of nanowire/nanotube based devices such as flexible electronics and sensors have been demonstrated. This paper delivers an overall review of directed nanowire/nanotube assembling approaches and analyzes advantages and limitations of each method. The future research directions have also been discussed.

  1. Semiconductor nanowire lasers

    Science.gov (United States)

    Eaton, Samuel W.; Fu, Anthony; Wong, Andrew B.; Ning, Cun-Zheng; Yang, Peidong

    2016-06-01

    The discovery and continued development of the laser has revolutionized both science and industry. The advent of miniaturized, semiconductor lasers has made this technology an integral part of everyday life. Exciting research continues with a new focus on nanowire lasers because of their great potential in the field of optoelectronics. In this Review, we explore the latest advancements in the development of nanowire lasers and offer our perspective on future improvements and trends. We discuss fundamental material considerations and the latest, most effective materials for nanowire lasers. A discussion of novel cavity designs and amplification methods is followed by some of the latest work on surface plasmon polariton nanowire lasers. Finally, exciting new reports of electrically pumped nanowire lasers with the potential for integrated optoelectronic applications are described.

  2. Plasmonic engineering of metal-oxide nanowire heterojunctions in integrated nanowire rectification units

    Science.gov (United States)

    Lin, Luchan; Zou, Guisheng; Liu, Lei; Duley, Walt W.; Zhou, Y. Norman

    2016-05-01

    We show that irradiation with femtosecond laser pulses can produce robust nanowire heterojunctions in coupled non-wetting metal-oxide Ag-TiO2 structures. Simulations indicate that joining arises from the effect of strong plasmonic localization in the region of the junction. Strong electric field effects occur in both Ag and TiO2 resulting in the modification of both surfaces and an increase in wettability of TiO2, facilitating the interconnection of Ag and TiO2 nanowires. Irradiation leads to the creation of a thin layer of highly defected TiO2 in the contact region between the Ag and TiO2 nanowires. The presence of this layer allows the formation of a heterojunction and offers the possibility of engineering the electronic characteristics of interfacial structures. Rectifying junctions with single and bipolar properties have been generated in Ag-TiO2 nanowire circuits incorporating asymmetrical and symmetrical interfacial structures, respectively. This fabrication technique should be applicable for the interconnection of other heterogeneous metal-oxide nanowire components and demonstrates that femtosecond laser irradiation enables interfacial engineering for electronic applications of integrated nanowire structures.

  3. GaAs nanowires. Epitaxy, crystal structure-related properties and magnetic heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Hubmann, Joachim

    2016-07-01

    The intention of this work is twofold: On the one hand, we explore the controlability of GaAs nanowire growth concerning orientation, shape and crystal structure. These are necessary steps, since the growth of GaAs nanowires proceeds not necessarily uniformly, and in GaAs nanowires the in bulk unstable wurtzite phase, and the usual observed zinc-blende crystal phase may coexist in one and the same nanowire. On the other hand, we include ferromagnetic materials into GaAs nanowires. To do that, we produce either ''core/shell'' structures, where the GaAs nanowire is coated with a ferromagnetic ''shell'' material, or grow ferromagnetic nanoscale segments in GaAs nanowires.

  4. Bacterial gastroenteritis

    Science.gov (United States)

    Infectious diarrhea - bacterial gastroenteritis; Acute gastroenteritis; Gastroenteritis - bacterial ... Bacterial gastroenteritis can affect 1 person or a group of people who all ate the same food. It is ...

  5. Silicon nanowire hybrid photovoltaics

    KAUST Repository

    Garnett, Erik C.

    2010-06-01

    Silicon nanowire Schottky junction solar cells have been fabricated using n-type silicon nanowire arrays and a spin-coated conductive polymer (PEDOT). The polymer Schottky junction cells show superior surface passivation and open-circuit voltages compared to standard diffused junction cells with native oxide surfaces. External quantum efficiencies up to 88% were measured for these silicon nanowire/PEDOT solar cells further demonstrating excellent surface passivation. This process avoids high temperature processes which allows for low-cost substrates to be used. © 2010 IEEE.

  6. Magnetoresistance of nanosized magnetic configurations in single nanowires

    Science.gov (United States)

    Wegrowe, J.-E.; Gilbert, S.; Doudin, B.; Ansermet, J.-Ph.

    1998-03-01

    The problem of studying spin configurations at nanoscopic level is that magnetic measurements at this scale cannot be performed using usual magnetometers. We have shown that anisotropic magnetoresistance (AMR) measured with micro-contacts allows spin configurations of a single nanowire to be studied in details. The nanowires are diameter 50 nm and length 6000 nm and are produced by a combination of electrodeposition in track-etched membrane templates and sputtering technics. Magnetoresistance of well-defined spin configurations in single nanowires, like Curling magnetization reversal modes or domain wall, are measured.

  7. Programmability of nanowire networks

    Science.gov (United States)

    Bellew, A. T.; Bell, A. P.; McCarthy, E. K.; Fairfield, J. A.; Boland, J. J.

    2014-07-01

    Electrical connectivity in networks of nanoscale junctions must be better understood if nanowire devices are to be scaled up from single wires to functional material systems. We show that the natural connectivity behaviour found in random nanowire networks presents a new paradigm for creating multi-functional, programmable materials. In devices made from networks of Ni/NiO core-shell nanowires at different length scales, we discover the emergence of distinct behavioural regimes when networks are electrically stressed. We show that a small network, with few nanowire-nanowire junctions, acts as a unipolar resistive switch, demonstrating very high ON/OFF current ratios (>105). However, large networks of nanowires distribute an applied bias across a large number of junctions, and thus respond not by switching but instead by evolving connectivity. We demonstrate that these emergent properties lead to fault-tolerant materials whose resistance may be tuned, and which are capable of adaptively reconfiguring under stress. By combining these two behavioural regimes, we demonstrate that the same nanowire network may be programmed to act both as a metallic interconnect, and a resistive switch device with high ON/OFF ratio. These results enable the fabrication of programmable, multi-functional materials from random nanowire networks.Electrical connectivity in networks of nanoscale junctions must be better understood if nanowire devices are to be scaled up from single wires to functional material systems. We show that the natural connectivity behaviour found in random nanowire networks presents a new paradigm for creating multi-functional, programmable materials. In devices made from networks of Ni/NiO core-shell nanowires at different length scales, we discover the emergence of distinct behavioural regimes when networks are electrically stressed. We show that a small network, with few nanowire-nanowire junctions, acts as a unipolar resistive switch, demonstrating very high ON

  8. Plasmonic Properties of Vertically Aligned Nanowire Arrays

    OpenAIRE

    Hua Qi; Glembocki, O. J.; Prokes, S. M.

    2012-01-01

    Nanowires (NWs)/Ag sheath composites were produced to investigate plasmonic coupling between vertically aligned NWs for surface-enhanced Raman scattering (SERS) applications. In this investigation, two types of vertical NW arrays were studied; those of ZnO NWs grown on nanosphere lithography patterned sapphire substrate via vapor-liquid-solid (VLS) mechanism and Si NW arrays produced by wet chemical etching. Both types of vertical NW arrays were coated with a thin layer of silver by electrole...

  9. Biofunctionalized Magnetic Nanowires

    KAUST Repository

    Kosel, Jurgen

    2013-12-19

    Magnetic nanowires can be used as an alternative method overcoming the limitations of current cancer treatments that lack specificity and are highly cytotoxic. Nanowires are developed so that they selectively attach to cancer cells via antibodies, potentially destroying them when a magnetic field induces their vibration. This will transmit a mechanical force to the targeted cells, which is expected to induce apoptosis on the cancer cells.

  10. Multishelled Gold Nanowires

    OpenAIRE

    Bilalbegovic, G.

    1999-01-01

    The current miniaturization of electronic devices raises many questions about the properties of various materials at nanometre-scales. Recent molecular dynamics computer simulations have shown that small finite nanowires of gold exist as multishelled structures of lasting stability. These classical simulations are based on a well-tested embedded atom potential. Molecular dynamics simulation studies of metallic nanowires should help in developing methods for their fabrication, such as electron...

  11. Mesoscopic Models of Plants Composed of Metallic Nanowires

    OpenAIRE

    Strukova, Galina K.; Strukov, Gennady V.; Postnova, Evgeniya Yu.; Rusanov, Alexander Yu.; Veshchunov, Ivan S.

    2013-01-01

    Various metallic structures of complex shape resembling living plant organisms (biomimetics) are produced as a result of selfassembly of nanowires growing on porous membranes in the course of pulse current electrodeposition. These structures occur if the electroplating is continued after the nanowires appear on the membrane surface. By varying the membrane ge- ometry, pulse current electroplating parameters, and alternating electrodeposition from two baths composed of a variety of electrolyte...

  12. Cross-linking Bi2S3 ultrathin nanowires: a platform for nanostructure formation and biomolecule detection.

    Science.gov (United States)

    Cademartiri, Ludovico; Scotognella, Francesco; O'Brien, Paul G; Lotsch, Bettina V; Thomson, Jordan; Petrov, Srebri; Kherani, Nazir P; Ozin, Geoffrey A

    2009-04-01

    This paper describes the use of chemical cross-linking of ultrathin inorganic nanowires as a bottom-up strategy for nanostructure fabrication as well as a chemical detection platform. Nanowire microfibers are produced by spinning a nanowire dispersion into a cross-linker solution at room temperature. Nanomembranes with thicknesses down to 50 nm were obtained by injecting the nanowire dispersion at the cross-linker-solution/air interface. Furthermore, the sensitivity of the nanowire to amine cross-linkers allowed development of a novel sensing platform for small molecules, like the neurotransmitter serotonin, with detection limits in the picomolar regime. PMID:19256475

  13. Nanowire structures and electrical devices

    Science.gov (United States)

    Bezryadin, Alexey; Remeika, Mikas

    2010-07-06

    The present invention provides structures and devices comprising conductive segments and conductance constricting segments of a nanowire, such as metallic, superconducting or semiconducting nanowire. The present invention provides structures and devices comprising conductive nanowire segments and conductance constricting nanowire segments having accurately selected phases including crystalline and amorphous states, compositions, morphologies and physical dimensions, including selected cross sectional dimensions, shapes and lengths along the length of a nanowire. Further, the present invention provides methods of processing nanowires capable of patterning a nanowire to form a plurality of conductance constricting segments having selected positions along the length of a nanowire, including conductance constricting segments having reduced cross sectional dimensions and conductance constricting segments comprising one or more insulating materials such as metal oxides.

  14. Novel nanotubes and encapsulated nanowires

    Science.gov (United States)

    Terrones, M.; Hsu, W. K.; Schilder, A.; Terrones, H.; Grobert, N.; Hare, J. P.; Zhu, Y. Q.; Schwoerer, M.; Prassides, K.; Kroto, H. W.; Walton, D. R. M.

    Carbon nanotubes, with or without encapsulated material, generated by arc discharge and electrolytic techniques have been studied. Microcrystals of refractory carbides (i.e. NbC, TaC, MoC), contained in nanotubes and polyhedral particles, produced by arcing electrodes of graphite/metal mixtures, were analysed by high hesolution transmission electron microscopy (HRTEM) and X-ray powder diffraction. Encapsulation of MoC was found to give rise to an unusual stable form, namely face-centered-cubic MoC. SQUID measurements indicate that the encapsulated carbides exhibit superconducting transitions at about 10-12 K, thus they differ from carbon nanotubes/nanoparticles which do not superconduct. Four-probe and microwave (contactless) conductivity measurements indicate that most of the analysed samples behave as semiconductors. However, metallic transport was observed in specimens containing single conglomerated carbon nanotube bundles and boron-doped carbon nanotubes. Novel metallic βSn nanowires were produced by electrolysis of graphite electrodes immersed in molten LiCl/SnCl2 mixtures. Prolonged electron irradiation of these nanowires leads to axial growth and to dynamic transformations. These observations suggest ways in which materials may be modified by microencapsulation and irradiation.

  15. Raman spectra of silicon carbide small particles and nanowires

    Science.gov (United States)

    Wieligor, Monika; Wang, Yuejian; Zerda, T. W.

    2005-04-01

    Two manufacturing protocols of silicon carbide (SiC) nanowires are discussed. The Raman spectra of produced SiC nanowires are compared with spectra of SiC powders of various grain sizes. The temperature and pressure dependence of the Raman spectra for powders is similar to that of bulk crystals, but is different for nanowires. Frequency shifts, band broadenings and the presence of shoulders are discussed in terms of crystal size, character of defects and their population. The concentration of defects in synthesized nanowires depends on the sintering method. Raman intensity enhancement of the LO phonon was observed when the wavelength of the excitation laser was changed from 780 to 514 nm.

  16. Oligo and Poly-thiophene/Zno Hybrid Nanowire Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Briseno, Alejandro L.; Holcombe, Thomas W.; Boukai, Akram I.; Garnett, Erik C.; Shelton, Steve W.; Frechet, Jean J. M.; Yang, Peidong

    2009-11-03

    We demonstrate the basic operation of an organic/inorganic hybrid single nanowire solar cell. End-functionalized oligo- and polythiophenes were grafted onto ZnO nanowires to produce p-n heterojunction nanowires. The hybrid nanostructures were characterized via absorption and electron microscopy to determine the optoelectronic properties and to probe the morphology at the organic/inorganic interface. Individual nanowire solar cell devices exhibited well-resolved characteristics with efficiencies as high as 0.036percent, Jsc = 0.32 mA/cm2, Voc = 0.4 V, and a FF = 0.28 under AM 1.5 illumination with 100 mW/cm2 light intensity. These individual test structures will enable detailed analysis to be carried out in areas that have been difficult to study in bulk heterojunction devices.

  17. Raman spectra of silicon carbide small particles and nanowires

    International Nuclear Information System (INIS)

    Two manufacturing protocols of silicon carbide (SiC) nanowires are discussed. The Raman spectra of produced SiC nanowires are compared with spectra of SiC powders of various grain sizes. The temperature and pressure dependence of the Raman spectra for powders is similar to that of bulk crystals, but is different for nanowires. Frequency shifts, band broadenings and the presence of shoulders are discussed in terms of crystal size, character of defects and their population. The concentration of defects in synthesized nanowires depends on the sintering method. Raman intensity enhancement of the LO phonon was observed when the wavelength of the excitation laser was changed from 780 to 514 nm

  18. Preparation and Characterization of Amorphous Silicon Oxide Nanowires

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Large-scale amorphous silicon nanowires (SiNWs) with a diameter about 100 nm and a length of dozens of micrometers on silicon wafers were synthesized by thermal evaporation of silicon monoxide (SiO).Scanning electron microscope (SEM) and transmission electron microscope (TEM) observations show that the silicon nanowires are smooth.Selected area electron diffraction (SAED) shows that the silicon nanowires are amorphous and energy-dispersive X-ray spectroscopy (EDS) indicates that the nanowires have the composition of Si and O elements in an atomic ratio of 1:2, their composition approximates that of SiO2.SiO is considered to be used as a Si sources to produce SiNWs.We conclude that the growth mechanism is closely related to the defect structure and silicon monoxide followed by growth through an oxide-assisted vapor-solid reaction.

  19. Hysteresis loops and susceptibility of a transverse Ising nanowire

    International Nuclear Information System (INIS)

    In this work, the magnetization, susceptibility, and hysteresis loops of a magnetic nanowire are described by the transverse Ising model using the effective field theory within a probability distribution technique. The effects of the exchange interaction between core/shell and the external fields on the magnetization and the susceptibility of the system are examined. Some characteristic phenomena are found in the thermal variations, depending on the ratios of the physical parameters in the shell and the core. - Highlights: ► We use the effective-field theory with a probability distribution technique to investigate. ► The magnetic properties of a magnetic nanowire in the presence of both the longitudinal and the transverse field. ► Triple hysteresis loop patterns for magnetic nanowire are observed which may have potential in producing a multi-state memory. ► Our theoretical predictions may be a reference for future experimental studies on the magnetic nanowire.

  20. The Novel Semiconductor Nanowire Heterostructures

    Institute of Scientific and Technical Information of China (English)

    J.Q.Hu; Y.Bando; J.H.Zhan; D.Golberg

    2007-01-01

    1 Results If one-dimensional heterostructures with a well-defined compositional profile along the wire radial or axial direction can be realized within semiconductor nanowires, new nano-electronic devices,such as nano-waveguide and nano-capcipator, might be obtained. Here,we report the novel semiconducting nanowire heterostructures:(1) Si/ZnS side-to-side biaxial nanowires and ZnS/Si/ZnS sandwich-like triaxial nanowires[1],(2) Ga-Mg3N2 and Ga-ZnS metal-semiconductor nanowire heterojunctions[2-3]and (3) ...

  1. Nanowire mesh solar fuels generator

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Peidong; Chan, Candace; Sun, Jianwei; Liu, Bin

    2016-05-24

    This disclosure provides systems, methods, and apparatus related to a nanowire mesh solar fuels generator. In one aspect, a nanowire mesh solar fuels generator includes (1) a photoanode configured to perform water oxidation and (2) a photocathode configured to perform water reduction. The photocathode is in electrical contact with the photoanode. The photoanode may include a high surface area network of photoanode nanowires. The photocathode may include a high surface area network of photocathode nanowires. In some embodiments, the nanowire mesh solar fuels generator may include an ion conductive polymer infiltrating the photoanode and the photocathode in the region where the photocathode is in electrical contact with the photoanode.

  2. Single-nanowire photoelectrochemistry

    Science.gov (United States)

    Su, Yude; Liu, Chong; Brittman, Sarah; Tang, Jinyao; Fu, Anthony; Kornienko, Nikolay; Kong, Qiao; Yang, Peidong

    2016-07-01

    Photoelectrochemistry is one of several promising approaches for the realization of efficient solar-to-fuel conversion. Recent work has shown that photoelectrodes made of semiconductor nano-/microwire arrays can have better photoelectrochemical performance than their planar counterparts because of their unique properties, such as high surface area. Although considerable research effort has focused on studying wire arrays, the inhomogeneity in the geometry, doping, defects and catalyst loading present in such arrays can obscure the link between these properties and the photoelectrochemical performance of the wires, and correlating performance with the specific properties of individual wires is difficult because of ensemble averaging. Here, we show that a single-nanowire-based photoelectrode platform can be used to reliably probe the current–voltage (I–V) characteristics of individual nanowires. We find that the photovoltage output of ensemble array samples can be limited by poorly performing individual wires, which highlights the importance of improving nanowire homogeneity within an array. Furthermore, the platform allows the flux of photogenerated electrons to be quantified as a function of the lengths and diameters of individual nanowires, and we find that the flux over the entire nanowire surface (7–30 electrons nm–2 s–1) is significantly reduced as compared with that of a planar analogue (∼1,200 electrons nm–2 s–1). Such characterization of the photogenerated carrier flux at the semiconductor/electrolyte interface is essential for designing nanowire photoelectrodes that match the activity of their loaded electrocatalysts.

  3. Electrodeposition of Cobalt Nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Sungbok; Hong, Kimin [Chungnam National Univ., Daejeon (Korea, Republic of)

    2013-03-15

    We developed an electroplating process of cobalt nanowires of which line-widths were between 70 and 200 nm. The plating electrolyte was made of CoSO{sub 4} and an organic additive, dimethyldithiocarbamic acid ester sodium salt (DAESA). DAESA in plating electrolytes had an accelerating effect and reduced the surface roughness of plated cobalt thin films. We obtained void-free cobalt nanowires when the plating current density was 6.25 mA/cm{sup 2} and DAESA concentration was 1 mL/L.

  4. Structural and magnetic properties of electrodeposited Cobalt nanowire arrays

    Science.gov (United States)

    Sharma, S.; Barman, A.; Sharma, M.; Shelford, L. R.; Kruglyak, V. V.; Hicken, R. J.

    2009-10-01

    Ordered magnetic nanowires have tremendous potential in future magnetic storage and high frequency magnetic logic devices. Here, we present the fabrication of ordered arrays of Cobalt nanowires by electrodeposition through porous polycarbonate membranes. Vertically and horizontally aligned nanowires were produced in presence of an external bias field during post deposition etching of the polycarbonate membrane. Structural and compositional analyses have been carried out to establish the material and structural purity. The magneto-optical Kerr effect was employed to measure the magnetic hysteresis loops for the nanowires assembled in the substrate plane. A good magneto-optical signal to noise ratio is observed with clean ferromagnetic hysteresis loops. The loops measured with external magnetic field applied parallel and perpendicular to the axis of the nanowires show a clear difference in the shape and the coercive field, indicating the effect of shape anisotropy in these samples. Micromagnetic simulations were performed to understand the experimental results and to obtain insight to the magnetization reversal mechanism in magnetic nanowires.

  5. Magnetron sputtering synthesis of large area well-ordered boron nanowire arrays

    Institute of Scientific and Technical Information of China (English)

    CAO; Limin; ZHANG; Ze; WANG; Wenkui

    2004-01-01

    One-dimensionally nanostructured materials, such as nanowires and nanotubes, are the smallest dimensional structures for efficient transport of electrons and excitons, and are therefore critical building blocks for nanoscale electronic and mechanical devices. In this paper, boron nanowires with uniform diameters from 20 to 80nm were synthesized by radio-frequency magnetron sputtering of pure boron powder and B2O3 powder mixtures in argon atmosphere. The boron nanowires produced stand vertically on the substrate surface to form well-ordered arrays over large areas with selforganized arrangements without involvement of any template and patterned catalyst. The high-density boron nanowires are parallel to each other and well distributed, forming highly ordered and uniform arrays. A more interesting and unique feature of the boron nanowires is that most of their tips are flat rather than hemispherical in morphologies.Detailed studies on its structure and composition indicate that boron nanowires are amorphous. Boron nanowire appears as a new member in the family of one-dimensional nanostructures. Considering the unique properties of boron-rich solids and other nanostructures, it is reasonable to expect that the boron nanowires will display some exceptional and interesting properties. A vapor-cluster-solid (VCS) mechanism was proposed to explain the growth of boron nanowires based on our experimental observations.

  6. Ice microsphere templating to produce highly porous nanocomposite PLA matrix scaffolds with pores selectively lined by bacterial cellulose nano-whiskers

    OpenAIRE

    Blaker, J. J.; Lee, K-Y; Mantalaris, A.; Bismarck, A.

    2010-01-01

    Abstract The production of 3D scaffolds for tissue engineering with provision of a controlled nano-topography remains a significant challenge. Here we have combined an ice microsphere templating technique with thermally induced phase separation, and by taking advantage of interactions between hydrophilic and hydrophobic phases, lined the pore walls with bacterial cellulose nano-whiskers. The cryogenic technique we have developed not only allows the decoration of the pore walls of 3...

  7. Formation of Germanium Nitride Nanowires on the Surface of Crystalline Germanium

    International Nuclear Information System (INIS)

    We report on the growth mechanisms of germanium nitride nanowires on the surface of crystalline Ge annealed in hydrazine vapor at different temperatures. In spite of the presence of water (and hence oxygen precursors) in hydrazine, the pure germanium nitride single crystal nanowires were produced in the temperature range of 480-580 degree C. At temperatures below 520 degree C, the GeOx clusters were formed first at the Ge surface, followed by the nucleation and growth of nanowires through the Vapor-Liquid-Solid mechanism. The Vapor-Solid growth mechanism was observed at temperatures exceeding 520 degree C, and Ge3N4 nanobelts were produced instead of nanowires with circular cross-sections. All nanostructures have the alpha germanium nitride structure; however, at the nucleation stage, the presence of beta Ge3N4 phase was also observed in the roots of nanowires.

  8. Fabrication of ultrahigh-density nanowires by electrochemical nanolithography

    Directory of Open Access Journals (Sweden)

    Jiang Hongquan

    2011-01-01

    Full Text Available Abstract An approach has been developed to produce silver nanoparticles (AgNPs rapidly on semiconductor wafers using electrochemical deposition. The closely packed AgNPs have a density of up to 1.4 × 1011 cm-2 with good size uniformity. AgNPs retain their shape and position on the substrate when used as nanomasks for producing ultrahigh-density vertical nanowire arrays with controllable size, making it a one-step nanolithography technique. We demonstrate this method on Si/SiGe multilayer superlattices using electrochemical nanopatterning and plasma etching to obtain high-density Si/SiGe multilayer superlattice nanowires.

  9. In-plane trapping and manipulation of ZnO nanowires by a hybrid plasmonic field.

    Science.gov (United States)

    Zhang, Lichao; Dou, Xiujie; Min, Changjun; Zhang, Yuquan; Du, Luping; Xie, Zhenwei; Shen, Junfeng; Zeng, Yujia; Yuan, Xiaocong

    2016-05-14

    In general, when a semiconductor nanowire is trapped by conventional laser beam tweezers, it tends to be aligned with the trapping beam axis rather than confined in the horizontal plane, and this limits the application of these nanowires in many in-plane nanoscale optoelectronic devices. In this work, we achieve the in-plane trapping and manipulation of a single ZnO nanowire by a hybrid plasmonic tweezer system on a flat metal surface. The gap between the nanowire and the metallic substrate leads to an enhanced gradient force caused by deep subwavelength optical energy confinement. As a result, the nanowire can be securely trapped in-plane at the center of the excited surface plasmon polariton field, and can also be dynamically moved and rotated by varying the position and polarization direction of the incident laser beam, which cannot be performed using conventional optical tweezers. The theoretical results show that the focused plasmonic field induces a strong in-plane trapping force and a high rotational torque on the nanowire, while the focused optical field produces a vertical trapping force to produce the upright alignment of the nanowire; this is in good agreement with the experimental results. Finally, some typical ZnO nanowire structures are built based on this technique, which thus further confirms the potential of this method for precise manipulation of components during the production of nanoelectronic and nanophotonic devices. PMID:27117313

  10. Electric Conductivity of Phosphorus Nanowires

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jing-Xiang; LI Hui; ZHANG Xue-Qing; LIEW Kim-Meow

    2009-01-01

    We present the structures and electrical transport properties of nanowires made from different strands of phosphorus chains encapsulated in carbon nanotubes. Optimized by density function theory, our results indicate that the conductance spectra reveal an oscillation dependence on the size of wires. It can be seen from the density of states and current-voltage curves that the structure of nanowires affects their properties greatly. Among them,the DNA-like double-helical phosphorus nanowire exhibits the distinct characteristic of an approximately linear I - V relationship and has a higher conductance than others. The transport properties of phosphorus nanowires are highly correlated with their microstructures.

  11. Silicon nanowire transistors

    CERN Document Server

    Bindal, Ahmet

    2016-01-01

    This book describes the n and p-channel Silicon Nanowire Transistor (SNT) designs with single and dual-work functions, emphasizing low static and dynamic power consumption. The authors describe a process flow for fabrication and generate SPICE models for building various digital and analog circuits. These include an SRAM, a baseband spread spectrum transmitter, a neuron cell and a Field Programmable Gate Array (FPGA) platform in the digital domain, as well as high bandwidth single-stage and operational amplifiers, RF communication circuits in the analog domain, in order to show this technology’s true potential for the next generation VLSI. Describes Silicon Nanowire (SNW) Transistors, as vertically constructed MOS n and p-channel transistors, with low static and dynamic power consumption and small layout footprint; Targets System-on-Chip (SoC) design, supporting very high transistor count (ULSI), minimal power consumption requiring inexpensive substrates for packaging; Enables fabrication of different types...

  12. Nanowire liquid pumps

    Science.gov (United States)

    Huang, Jian Yu; Lo, Yu-Chieh; Niu, Jun Jie; Kushima, Akihiro; Qian, Xiaofeng; Zhong, Li; Mao, Scott X.; Li, Ju

    2013-04-01

    The ability to form tiny droplets of liquids and control their movements is important in printing or patterning, chemical reactions and biological assays. So far, such nanofluidic capabilities have principally used components such as channels, nozzles or tubes, where a solid encloses the transported liquid. Here, we show that liquids can flow along the outer surface of solid nanowires at a scale of attolitres per second and the process can be directly imaged with in situ transmission electron microscopy. Microscopy videos show that an ionic liquid can be pumped along tin dioxide, silicon or zinc oxide nanowires as a thin precursor film or as beads riding on the precursor film. Theoretical analysis suggests there is a critical film thickness of ~10 nm below which the liquid flows as a flat film and above which it flows as discrete beads. This critical thickness is the result of intermolecular forces between solid and liquid, which compete with liquid surface energy and Rayleigh-Plateau instability.

  13. Optimization of culture conditions of producing bacterial cellulose utilizing starch wastewater%淀粉废水发酵产细菌纤维素发酵条件的优化

    Institute of Scientific and Technical Information of China (English)

    徐伟; 张妍; 傅徐阳

    2012-01-01

    The culture conditions of Gluconacetobacter xylinus producing bacterial cellulose utilizing corn starch wastewater(adding glucose 20g/L,corn steep liquor 40g/L,ethanol 150mL/L) were investigated through singlefactor and orthogonal tests. The suitable culture conditions were as follows.liquid level was 80mL in 250mL triangle bottle,pH4.0,inoculation volume was 9% (VN),culture temperature was 28℃ ,the the yield of bacterial cellulose reached the peak(4.41g/L) at this time. The bacterial cellulose was verified by FTIR,SEM was used to observe the surface pattern of bacterial cellulose membrane.%以玉米淀粉废水添加葡萄糖20g/L,玉米浆40班,乙醇150mL/L为发酵基质,采用单因素和正交实验设计对葡糖醋杆菌(Gluconacetobacter xylinus)发酵产细菌纤维素条件进行优化。结果表明,最佳发酵条件为:装液量80mL/250mL,pH4.0,接种量9%(V/V),温度28℃;在此条件下得到细菌纤维素产量为4.41g/L。采用傅立叶转换红外光谱FTIR验证产物为细菌纤维素,并由SEM扫描电镜观察纤维素膜表面形貌。

  14. GaN nanowire arrays by a patterned metal-assisted chemical etching

    Science.gov (United States)

    Wang, K. C.; Yuan, G. D.; Wu, R. W.; Lu, H. X.; Liu, Z. Q.; Wei, T. B.; Wang, J. X.; Li, J. M.; Zhang, W. J.

    2016-04-01

    We developed an one-step and two-step metal-assisted chemical etching method to produce self-organized GaN nanowire arrays. In one-step approach, GaN nanowire arrays are synthesized uniformly on GaN thin film surface. However, in a two-step etching processes, GaN nanowires are formed only in metal uncovered regions, and GaN regions with metal-covering show nano-porous sidewalls. We propose that nanowires and porous nanostructures are tuned by sufficient and limited etch rate, respectively. PL spectra shows a red-shift of band edge emission in GaN nanostructures. The formation mechanism of nanowires was illustrated by two separated electrochemical reactions occur simultaneously. The function of metals and UV light was illustrated by the scheme of potential relationship between energy bands in Si, GaN and standard hydrogen electrode potential of solution and metals.

  15. Suppression of superconductivity in thin Nb nanowires fabricated in the vortex cores of superfluid helium

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, Eugene B., E-mail: Gordon.eb@gmail.com [Institute of Problems of Chemical Physics RAS, Semenov Avenue 1, 142432 Chernogolovka, Moscow Region (Russian Federation); Bezryadin, Alexey V. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61874 (United States); Karabulin, Alexander V. [Institute of Problems of Chemical Physics RAS, Semenov Avenue 1, 142432 Chernogolovka, Moscow Region (Russian Federation); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoe Highway 31, 115409 Moscow (Russian Federation); Matyushenko, Vladimir I. [The Branch of Talrose Institute for Energy Problems of Chemical Physics RAS, Semenov Avenue 1/10, 142432 Chernogolovka, Moscow Region (Russian Federation); Khodos, Igor I. [Institute of Microelectronics Technology and High Purity Materials RAS, Institutskaya Street 6, 142432 Chernogolovka, Moscow Region (Russian Federation)

    2015-09-15

    Highlights: • Laser ablation in superfluid helium allows producing thin nanowires of any metal. • Nb nanowires, about 4 nm in diameter, form in the cores of superfluid vortices. • Our oxide-free Nb nanowires exhibit a quantum superconductor-to-insulator transition. • The insulating behavior in Nb wires is explained in terms of quantum phase slips. • Such nanowires can be used in superconducting phase-slip qubits and transistors. - Abstract: Nanowires of niobium, platinum and indium–lead In{sub 88}Pb{sub 12} alloy with diameters of 4.2, 3.6 and 8 nm, respectively, were grown in quantized vortices of superfluid helium, and the dependences of their resistance on temperature have been studied. Through a detailed comparison of these dependences we present evidence that superconducting niobium wires allow a high rate of quantum phase slip. This phase slippage leads to a phase transition to an insulating state at T → 0.

  16. Bismuth nanowire growth under low deposition rate and its ohmic contact free of interface damage

    Directory of Open Access Journals (Sweden)

    Ye Tian

    2012-03-01

    Full Text Available High quality bismuth (Bi nanowire and its ohmic contact free of interface damage are quite desired for its research and application. In this paper, we propose one new way to prepare high-quality single crystal Bi nanowires at a low deposition rate, by magnetron sputtering method without the assistance of template or catalyst. The slow deposition growth mechanism of Bi nanowire is successfully explained by an anisotropic corner crossing effect, which is very different from existing explanations. A novel approach free of interface damage to ohmic contact of Bi nanowire is proposed and its good electrical conductivity is confirmed by I-V characteristic measurement. Our method provides a quick and convenient way to produce high-quality Bi nanowires and construct ohmic contact for desirable devices.

  17. Quantum transport in semiconductor nanowires

    NARCIS (Netherlands)

    Van Dam, J.

    2006-01-01

    This thesis describes a series of experiments aimed at understanding the low-temperature electrical transport properties of semiconductor nanowires. The semiconductor nanowires (1-100 nm in diameter) are grown from nanoscale gold particles via a chemical process called vapor-liquid-solid (VLS) growt

  18. Improving information storage by means of segmented magnetic nanowires

    International Nuclear Information System (INIS)

    A set of magnetic nanowires trapped in the membrane used to produce them can be employed to inscribe information in the form of sectors of wires with the same ferromagnetic orientation (Cisternas and Vogel, 2013 [1]). However, such a system relays on the shape anisotropy of each nanowire as the stabilizing mechanism avoiding magnetization reversal. Such stabilization mechanism weakens as the size of the nanowires decrease. In the present paper we introduce a way of using segmented nanowires to produce a self-stabilization mechanism based on the fact that interactions among segments of different layers can contribute with negative energies. Then, for some particular geometries it is possible to make this interaction the most important one producing a more stable system with respect to spontaneous magnetization reversal. Such inscribed ferromagnetic sector will then last longer than other ferromagnetic sectors formed by exclusively repelling elements. We make use of available algebraic expressions to calculate the energy contribution of noncoaxial segments. For the coaxial segments a similar expression is developed here and it is applied to real systems. The total interaction energy for all segments in the system is calculated for different geometrical possibilities. Application to two particular symbols (letters T and O) is fully discussed bringing out general aspects that could be applied to other symbols. Projections of this work are finally mentioned. - Highlights: • Information storage on magnetic nanowires trapped in the fabrication membrane. • Calculations of the energy trying to revert the magnetization of the stored patterns. • Self-stabilization mechanism based on interactions of multisegmented nanowire. • Choice of geometrical parameters leads to negative energies allowing stability

  19. Bacterial Type I Glutamine Synthetase of the Rifamycin SV Producing Actinomycete, Amycolatopsis mediterranei U32, is the Only Enzyme Responsible for Glutamine Synthesis under Physiological Conditions

    Institute of Scientific and Technical Information of China (English)

    Wen-Tao PENG; Jin WANG; Ting WU; Jian-Qiang HUANG; Jui-Shen CHIAO; Guo-Ping ZHAO

    2006-01-01

    The structural gene for glutamine synthetase, glnA, from Amycolatopsis mediterranei U32 was cloned via screening a genomic library using the analog gene from Streptomyces coelicolor. The clone was functionally verified by complementing for glutamine requirement of an Escherichia coli glnA null mutant under the control of a lac promoter. Sequence analysis showed an open reading frame encoding a protein of466 amino acid residues. The deduced amino acid sequence bears significant homologies to other bacterial type I glutamine synthetases, specifically, 71% and 72% identical to the enzymes of S. coelicolor and Mycobacterium tuberculosis, respectively. Disruption of this glnA gene in A. mediterranei U32 led to glutamine auxotrophy with no detectable glutamine synthetase activity in vivo. In contrast, the cloned glnA+ gene can complement for both phenotypes in trans. It thus suggested that in A. mediterranei U32, the glnA gene encoding glutamine synthetase is uniquely responsible for in vivo glutamine synthesis under our laboratory defined physiological conditions.

  20. Ordered Mesostructured CdS Nanowire Arrays with Rectifying Properties

    Directory of Open Access Journals (Sweden)

    Yuan Na

    2009-01-01

    Full Text Available Abstract Highly ordered mesoporous CdS nanowire arrays were synthesized by using mesoporous silica as hard template and cadmium xanthate (CdR2 as a single precursor. Upon etching silica, mesoporous CdS nanowire arrays were produced with a yield as high as 93 wt%. The nanowire arrays were characterized by XRD, N2adsorption, TEM, and SEM. The results show that the CdS products replicated from the mesoporous silica SBA-15 hard template possess highly ordered hexagonal mesostructure and fiber-like morphology, analogous to the mother template. The current–voltage characteristics of CdS nanoarrays are strongly nonlinear and asymmetrical, showing rectifying diode-like behavior.

  1. Novel nanotubes and encapsulated nanowires

    International Nuclear Information System (INIS)

    Carbon nanotubes, with or without encapsulated material, generated by arcdischarge and electrolytic techniques have been studied. Microcrystals of refractory carbides (i.e. NbC, TaC, MoC), contained in nanotubes and polyhedral particles, produced by arcing electrodes of graphite/metal mixtures, were analysed by high resolution transmission electron microscopy (HRTEM) and X-ray powder diffraction. Encapsulation of MoC was found to give rise to an unusual stable form, namely face-centered-cubic MoC. SQUID measurements indicate that the encapsulated carbides exhibit superconducting transitions at about 10-12 K, thus they differ from carbon nanotubes/nanoparticles which do not superconduct. Four-probe and microwave (contactless) conductivity measurements indicate that most of the analysed samples behave as semiconductors. However, metallic transport was observed in specimens containing single conglomerated carbon nanotube bundles and boron-doped carbon nanotubes. Novel metallic βSn nanowires were produced by electrolysis of graphite electrodes immersed in molten LiCl/SnCl2 mixtures. Prolonged electron irradiation of these nanowiresleads to axial growth and to dynamic transformations. These observations suggest ways in which materials may be modified by microencapsulation and irradiation. (orig.)

  2. Complete Genome Sequence of a Gluconacetobacter hansenii ATCC 23769 Isolate, AY201, Producer of Bacterial Cellulose and Important Model Organism for the Study of Cellulose Biosynthesis

    Science.gov (United States)

    Mehta, Kalpa

    2016-01-01

    The cellulose producer and model organism used for the study of cellulose biosynthesis, Gluconacetobacter hansenii AY201, is a variant of G. hansenii ATCC 23769. We report here the complete nucleotide sequence of G. hansenii AY201, information which may be utilized to further the research into understanding the genes necessary for cellulose biosynthesis. PMID:27516506

  3. Complete Genome Sequence of a Gluconacetobacter hansenii ATCC 23769 Isolate, AY201, Producer of Bacterial Cellulose and Important Model Organism for the Study of Cellulose Biosynthesis.

    Science.gov (United States)

    Pfeffer, Sarah; Mehta, Kalpa; Brown, R Malcolm

    2016-01-01

    The cellulose producer and model organism used for the study of cellulose biosynthesis, Gluconacetobacter hansenii AY201, is a variant of G. hansenii ATCC 23769. We report here the complete nucleotide sequence of G. hansenii AY201, information which may be utilized to further the research into understanding the genes necessary for cellulose biosynthesis. PMID:27516506

  4. 细菌纤维素膜对木醋杆菌发酵生产广式米醋的影响%Effect of Bacterial Cellulose Pellicle on Gluconacetobacter xylinus Fermentation Producing Guangdong Rice Vinegar

    Institute of Scientific and Technical Information of China (English)

    傅亮; 陈思谦; 易九龙; 吴炳鸿

    2012-01-01

    Isolated from a Guangdong rice vinegar factory, the RF4 Gluconacetobacter xylinus is used to produce rice vinegar by surface fermentation. The effect of intact bacterial cellulose peUicle on total acidity in fermentation, the comparison of ADH enzyme activity in the pellicle and liquor, and the influence of inoculation methods on acidity, viscosity and turbidity are researched. The results show that the morphology of bacterial cellulose pellicle is very im- portant to total acidity produced, and the ADH enzyme activity in the bacterial cellulose pellicle is 2.26 x 10-2U/g, 8 times of that in the liquor. The highest acidity achieved when bacterial cellulose pellicle was inoculated with Glu- conacetobacter xylinus, 12 days accompanying and was taken out during the fermentation, resulting in a high yielding of 4.86g/100mL after by low viscosity and turbidity.%以分离自广式米醋生产车间的木醋杆菌RF4(Gluconacetobacter xylinus)为菌种进行表面发酵。研究了发酵过程中细菌纤维素膜对总酸度的影响,纤维素膜内与发酵液中乙醇脱氢酶活性差异,讨论了3种不同接种培养方式对总酸度、黏度及浑浊度的影响。结果表明,纤维素膜完整性对发酵总酸度有重要影响,纤维素膜内乙醇脱氢酶活性是发酵液中的8倍,达2.26×10-2U/g。含木醋杆菌纤维素膜接种并中途取出的接种培养方式总酸度最高,发酵12天后可达4.86 g/100 mL,且黏度及浑浊度都较低。

  5. Non-chromatographic preparation of a bacterially produced single-shot modular virus-like particle capsomere vaccine for avian influenza.

    Science.gov (United States)

    Wibowo, Nani; Wu, Yang; Fan, Yuanyuan; Meers, Joanne; Lua, Linda H L; Middelberg, Anton P J

    2015-11-01

    Highly pathogenic avian influenza (HPAI) causes significant economic loss, reduced food security and poses an ongoing pandemic threat. Poultry vaccination significantly decreases these problems and recognizes that the health of humans, animals and ecosystems are connected. Low-cost manufacture of poultry vaccine matched quickly to the ever-changing circulating strain is needed for effective vaccination. Here, we re-engineered the process to manufacture bacterially synthesized modular capsomere comprising influenza M2e, previously shown to confer complete protection in challenged mice, for application in poultry. Modular capsomere was prepared using a simplified non-chromatographic salting-out precipitation method and its immunogenicity tested in vivo in poultry. Modular capsomere crudely purified by precipitation (pCapM2e) contained more contaminants than equivalent product purified by chromatography (cCapM2e). Unadjuvanted pCapM2e containing 80 EU of endotoxin per dose was inferior to highly purified and adjuvanted cCapM2e (2 EU per dose). However, addition of adjuvant to pCapM2e resulting in high immunogenicity after only a single dose of vaccination, yet without any local adverse reaction. This finding suggests a strong synergy between adjuvant, antigen and contaminants, and the possible existence of a "Goldilocks" level of contaminants, where high immunogenicity and low reactogenicity can be obtained in a single-shot vaccination. The simplified process offers potential cost and speed advantages to address the needs in influenza poultry vaccination in low-cost veterinary markets. PMID:26407921

  6. Analysis of Bacterial Community and Screening and Identification of Enzyme-Producing Bacteria in Intestine of Antheraea pernyi%柞蚕肠道菌群分析及产酶菌的筛选与鉴定

    Institute of Scientific and Technical Information of China (English)

    邹昌瑞; 魏国清; 刘朝良; 朱保建; 王在贵; 杨文静

    2011-01-01

    [目的]研究柞蚕肠道菌群结构及产酶菌,探寻具有新的生理功能的微生物,用于研制微生态制剂,以提高柞蚕生产的叶丝转化率及抗病能力.[方法]采用培养法分离柞树叶饲喂的5龄柞蚕幼虫肠道细菌,通过生理生化特性结合16S rDNA系统发育分析,对其肠道细菌群落类型进行鉴定,采用筛选培养基筛选产纤维素酶、蛋白酶、脂肪酶的菌株.[结果]获得的柞蚕肠道菌有芽孢杆菌、葡萄球菌、肠杆菌,其中以芽孢杆菌为主要菌群.芽孢杆菌是肠道菌中产纤维素酶、蛋白酶的主要菌群;葡萄球菌产蛋白酶能力较弱;肠杆菌不产酶.[结论]柞蚕肠道菌与家蚕肠道菌群结构相似,筛选出的产酶菌活性较高,可以制备微生态制剂用于蚕业生产.%[Objective] The objective of this study is to isolate and identify bacterial community and enzyme-producing bacteria in intestine of Antheraea pernyi larvae and to develop microecological agents for increasing leaf-silk conversation rate and disease resistance. [ Method ] Bacteria were isolated from intestine of fifth instars Antheraea pernyi larvae reared on oak leaves by isolated culture. Intestinal bacterial community was identified according to physiological and biochemical characteristics and phylogenetic analysis based on 16S rDNA sequences. Cellulase, protease, lipase-producing strains were screened on selective medium. [Result] The intestinal bacteria isolated from Antheraea pernyi larvae belong to Bacillus, Staphylococcus and Enterobacter. Among them, Bacillus is the main bacteria and the main enzyme-producing bacteria which could produce cellulase and protease, Staphylococcus could produce protease weakly, Enterobacter couldn't produce enzyme. [Conclusion] Intestinal bacteria community of Antheraea pernyi was similar to that of Bombyx mori, which could be developed as microecological agents in sericulture for the enzyme-producing strains exhibiting high activity.

  7. Lattice dislocation in Si nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Omar, M.S., E-mail: dr_m_s_omar@yahoo.co [Department of Physics, College of Science, University of Salahaddin, Arbil, Iraqi Kurdistan (Iraq); Taha, H.T. [Department of Physics, College of Science, University of Salahaddin, Arbil, Iraqi Kurdistan (Iraq)

    2009-12-15

    Modified formulas were used to calculate lattice thermal expansion, specific heat and Bulk modulus for Si nanowires with diameters of 115, 56, 37 and 22 nm. From these values and Gruneisen parameter taken from reference, mean lattice volumes were found to be as 20.03 A{sup 3} for the bulk and 23.63, 29.91, 34.69 and 40.46 A{sup 3} for Si nanowire diameters mentioned above, respectively. Their mean bonding length was calculated to be as 0.235 nm for the bulk and 0.248, 0.269, 0.282 and 0.297 nm for the nanowires diameter mentioned above, respectively. By dividing the nanowires diameter on the mean bonding length, number of layers per each nanowire size was found to be as 230, 104, 65 and 37 for the diameters mentioned above, respectively. Lattice dislocations in 22 nm diameter wire were found to be from 0.00324 nm for the 1st central lattice to 0.2579 nm for the last surface lattice. Such dislocation was smaller for larger wire diameters. Dislocation concentration found to change in Si nanowires according to the proportionalities of surface thickness to nanowire radius ratios.

  8. X-ray diffraction from single GaAs nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Biermanns, Andreas

    2012-11-12

    In recent years, developments in X-ray focussing optics have allowed to produce highly intense, coherent X-ray beams with spot sizes in the range of 100 nm and below. Together with the development of new experimental stations, X-ray diffraction techniques can now be applied to study single nanometer-sized objects. In the present work, X-ray diffraction is applied to study different aspects of the epitaxial growth of GaAs nanowires. Besides conventional diffraction methods, which employ X-ray beams with dimensions of several tens of {mu}m, special emphasis lies on the use of nanodiffraction methods which allow to study single nanowires in their as-grown state without further preparation. In particular, coherent X-ray diffraction is applied to measure simultaneously the 3-dimensional shape and lattice parameters of GaAs nanowires grown by metal-organic vapor phase epitaxy. It is observed that due to a high density of zinc-blende rotational twins within the nanowires, their lattice parameter deviates systematically from the bulk zinc-blende phase. In a second step, the initial stage in the growth of GaAs nanowires on Si (1 1 1) surfaces is studied. This nanowires, obtained by Ga-assisted growth in molecular beam epitaxy, grow predominantly in the cubic zinc-blende structure, but contain inclusions of the hexagonal wurtzite phase close to their bottom interface. Using nanodiffraction methods, the position of the different structural units along the growth axis is determined. Because the GaAs lattice is 4% larger than silicon, these nanowires release their lattice mismatch by the inclusion of dislocations at the interface. Whereas NWs with diameters below 50 nm are free of strain, a rough interface structure in nanowires with diameters above 100 nm prevents a complete plastic relaxation, leading to a residual strain at the interface that decays elastically along the growth direction. Finally, measurements on GaAs-core/InAs-shell nanowire heterostructures are presented

  9. Do transgenesis and marker-assisted backcross breeding produce substantially equivalent plants? - A comparative study of transgenic and backcross rice carrying bacterial blight resistant gene Xa21

    OpenAIRE

    Gao, Lifen; Cao, Yinghao; Xia, Zhihui; Jiang, Guanghuai; Liu, Guozhen; Zhang, Weixiong; Zhai, Wenxue

    2013-01-01

    Background The potential impact of genetically modified (GM) plants on human health has attracted much attention worldwide, and the issue remains controversial. This is in sharp contrast to the broad acceptance of plants produced by breeding through Marker Assisted Backcrossing (MAB). Results Focusing on transcriptome variation and perturbation to signaling pathways, we assessed the molecular and biological aspects of substantial equivalence, a general principle for food safety endorsed by th...

  10. A bacterial symbiont is converted from an inedible producer of beneficial molecules into food by a single mutation in the gacA gene

    OpenAIRE

    Stallforth, Pierre; Brock, Debra A.; Cantley, Alexandra M.; Tian, Xiangjun; Queller, David C; Strassmann, Joan E.; Clardy, Jon

    2013-01-01

    Stable multipartite mutualistic associations require that all partners benefit. We show that a single mutational step is sufficient to turn a symbiotic bacterium from an inedible but host-beneficial secondary metabolite producer into a host food source. The bacteria’s host is a “farmer” clone of the social amoeba Dictyostelium discoideum that carries and disperses bacteria during its spore stage. Associated with the farmer are two strains of Pseudomonas fluorescens, only one of which serves a...

  11. Superconductivity in nanowires

    CERN Document Server

    Bezryadin, Alexey

    2012-01-01

    The importance and actuality of nanotechnology is unabated and will be for years to come. A main challenge is to understand the various properties of certain nanostructures, and how to generate structures with specific properties for use in actual applications in Electrical Engineering and Medicine.One of the most important structures are nanowires, in particular superconducting ones. They are highly promising for future electronics, transporting current without resistance and at scales of a few nanometers. To fabricate wires to certain defined standards however, is a major challenge, and so i

  12. Indium Arsenide Nanowires

    DEFF Research Database (Denmark)

    Madsen, Morten Hannibal

    substrates. The crystal structure of the NWs has also been investigated, and a method for obtaining pure wurtzite NWs with a well controlled diameter and length is presented. For self-assisted growth of InAs NWs a method for enhanced control of the nanowire morphology by pre-treatment of the oxide layer...... is presented. A series of experiments with formation of a droplet on top of the wires has been carried out and pyramidal shaped structures at the NW top with pure zinc blende crystal structure are observed. A novel in-situ experiment with fabrication of NWs and simultanous characterization using x...

  13. Simple, Inexpensive, and Rapid Approach to Fabricate Cross-Shaped Memristors Using an Inorganic-Nanowire-Digital-Alignment Technique and a One-Step Reduction Process.

    Science.gov (United States)

    Xu, Wentao; Lee, Yeongjun; Min, Sung-Yong; Park, Cheolmin; Lee, Tae-Woo

    2016-01-20

    A rapid, scalable, and designable approach to produce a cross-shaped memristor array is demonstrated using an inorganic-nanowire digital-alignment technique and a one-step reduction process. Two-dimensional arrays of perpendicularly aligned, individually conductive Cu-nanowires with a nanometer-scale Cux O layer sandwiched at each cross point are produced. PMID:26585580

  14. Nanowire terahertz quantum cascade lasers

    International Nuclear Information System (INIS)

    Quantum cascade lasers made of nanowire axial heterostructures are proposed. The dissipative quantum dynamics of their carriers is theoretically investigated using non-equilibrium Green functions. Their transport and gain properties are calculated for varying nanowire thickness, from the classical-wire regime to the quantum-wire regime. Our calculation shows that the lateral quantum confinement provided by the nanowires allows an increase of the maximum operation temperature and a strong reduction of the current density threshold compared to conventional terahertz quantum cascade lasers.

  15. Fivefold twinned boron carbide nanowires.

    Science.gov (United States)

    Fu, Xin; Jiang, Jun; Liu, Chao; Yuan, Jun

    2009-09-01

    Chemical composition and crystal structure of fivefold twinned boron carbide nanowires have been determined by electron energy-loss spectroscopy and electron diffraction. The fivefold cyclic twinning relationship is confirmed by systematic axial rotation electron diffraction. Detailed chemical analysis reveals a carbon-rich boron carbide phase. Such boron carbide nanowires are potentially interesting because of their intrinsic hardness and high temperature thermoelectric property. Together with other boron-rich compounds, they may form a set of multiply twinned nanowire systems where the misfit strain could be continuously tuned to influence their mechanical properties. PMID:19687534

  16. Single crystalline mesoporous silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Hochbaum, A.I.; Gargas, Daniel; Jeong Hwang, Yun; Yang, Peidong

    2009-08-04

    Herein we demonstrate a novel electroless etching synthesis of monolithic, single-crystalline, mesoporous silicon nanowire arrays with a high surface area and luminescent properties consistent with conventional porous silicon materials. These porous nanowires also retain the crystallographic orientation of the wafer from which they are etched. Electron microscopy and diffraction confirm their single-crystallinity and reveal the silicon surrounding the pores is as thin as several nanometers. Confocal fluorescence microscopy showed that the photoluminescence (PL) of these arrays emanate from the nanowires themselves, and their PL spectrum suggests that these arrays may be useful as photocatalytic substrates or active components of nanoscale optoelectronic devices.

  17. Fabrication of 30 nm pitch imprint moulds by frequency doubling for nanowire arrays

    International Nuclear Information System (INIS)

    We report the fabrication of 30 nm pitch nanowire array imprint moulds by spatial frequency doubling a 60 nm pitch array generated by electron beam lithography. We have successfully fabricated nanowire arrays at a 30 nm pitch, which is targeted for the year 2020 by the International Technology Roadmap for Semiconductors, with an average line-width of 17 nm and a 3σ line width roughness (LWR) of 4.0 nm. In contrast to previously reported procedures, our spatial frequency doubling technique produces electrically isolated nanowires that are appropriate for crossbar circuits

  18. Universal, geometry-driven hydrophobic behaviour of bare metal nanowire clusters

    International Nuclear Information System (INIS)

    A parallel array of isolated metal nanowires is expected to be hydrophilic. We show, however, that a clustering of such nanowires brought about by vacuum drying produces a 'dual-scale roughness' and confers a strongly hydrophobic property to the surface. The mean size of the nanowire clusters as well as the contact angle are both found to be related to the wire length, and the critical wire length above which the surface becomes hydrophobic is ∼10 μm. Surface roughness is generally known to enhance water-repellent properties, but this is the first report of roughness-induced hydrophobicity on a bare (uncoated) metallic surface

  19. Atmospheric pressure plasma produced inside a closed package by a dielectric barrier discharge in Ar/CO2 for bacterial inactivation of biological samples

    DEFF Research Database (Denmark)

    Chiper, Alina Silvia; Chen, Weifeng; Mejlholm, Ole;

    2011-01-01

    The generation and evaluation of a dielectric barrier discharge produced inside a closed package made of a commercially available packaging film and filled with gas mixtures of Ar/CO2 at atmospheric pressure is reported. The discharge parameters were analysed by electrical measurements and optical...... emission spectroscopy in two modes of operation: trapped gas atmosphere and flowing gas atmosphere. Gas temperature was estimated using the OH(A–X) emission spectrum and the rotational temperature reached a saturation level after a few minutes of plasma running. The rotational temperature was almost three...

  20. Compressive mechanical behavior of Au nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Wen Yuhua, E-mail: yhwen@xmu.edu.c [Department of Physics, and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen 361005 (China); Department of Mechanical and Manufacturing Engineering, University of Manitoba, Winnipeg, Manitoba, R3T 5V6 (Canada); Wang Quan, E-mail: q_wang@umanitoba.c [Department of Mechanical and Manufacturing Engineering, University of Manitoba, Winnipeg, Manitoba, R3T 5V6 (Canada); Liew, Kim Meow [Department of Building and Construction, City University of Hong Kong (Hong Kong); Zhu Zizhong [Department of Physics, and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen 361005 (China)

    2010-06-28

    The structural evolution, deformation mechanism, and failure behavior of Au [001] nanowires with various sizes and slenderness ratios under uniaxial compression have been investigated using molecular dynamics. The results show that the elastic modulus, yield stress, and strain all are dependent on the diameters and slenderness ratios of the nanowires. Buckling behavior is observed in a long nanowire, followed by slips in the {l_brace}111{r_brace} planes. Differences are identified in the failure behavior of a short nanowire and a medium nanowire, although the plastic deformation of both types of nanowire originates from the slips in the {l_brace}111{r_brace} planes.

  1. Compressive mechanical behavior of Au nanowires

    International Nuclear Information System (INIS)

    The structural evolution, deformation mechanism, and failure behavior of Au [001] nanowires with various sizes and slenderness ratios under uniaxial compression have been investigated using molecular dynamics. The results show that the elastic modulus, yield stress, and strain all are dependent on the diameters and slenderness ratios of the nanowires. Buckling behavior is observed in a long nanowire, followed by slips in the {111} planes. Differences are identified in the failure behavior of a short nanowire and a medium nanowire, although the plastic deformation of both types of nanowire originates from the slips in the {111} planes.

  2. Interactions between semiconductor nanowires and living cells

    International Nuclear Information System (INIS)

    Semiconductor nanowires are increasingly used for biological applications and their small dimensions make them a promising tool for sensing and manipulating cells with minimal perturbation. In order to interface cells with nanowires in a controlled fashion, it is essential to understand the interactions between nanowires and living cells. The present paper reviews current progress in the understanding of these interactions, with knowledge gathered from studies where living cells were interfaced with vertical nanowire arrays. The effect of nanowires on cells is reported in terms of viability, cell–nanowire interface morphology, cell behavior, changes in gene expression as well as cellular stress markers. Unexplored issues and unanswered questions are discussed. (topical review)

  3. Characterization of Cichopeptins, New Phytotoxic Cyclic Lipodepsipeptides Produced by Pseudomonas cichorii SF1-54 and Their Role in Bacterial Midrib Rot Disease of Lettuce.

    Science.gov (United States)

    Huang, Chien-Jui; Pauwelyn, Ellen; Ongena, Marc; Debois, Delphine; Leclère, Valerie; Jacques, Philippe; Bleyaert, Peter; Höfte, Monica

    2015-09-01

    The lettuce midrib rot pathogen Pseudomonas cichorii SF1-54 produces seven bioactive compounds with biosurfactant properties. Two compounds exhibited necrosis-inducing activity on chicory leaves. The structure of the two phytotoxic compounds, named cichopeptin A and B, was tentatively characterized. They are related cyclic lipopeptides composed of an unsaturated C12-fatty acid chain linked to the N-terminus of a 22-amino acid peptide moiety. Cichopeptin B differs from cichopeptin A only in the last C-terminal amino acid residue, which is probably Val instead of Leu/Ile. Based on peptide sequence similarity, cichopeptins are new cyclic lipopeptides related to corpeptin, produced by the tomato pathogen Pseudomonas corrugata. Production of cichopeptin is stimulated by glycine betaine but not by choline, an upstream precursor of glycine betaine. Furthermore, a gene cluster encoding cichopeptin synthethases, cipABCDEF, is responsible for cichopeptin biosynthesis. A cipA-deletion mutant exhibited significantly less virulence and rotten midribs than the parental strain upon spray inoculation on lettuce. However, the parental and mutant strains multiplied in lettuce leaves at a similar rate. These results demonstrate that cichopeptins contribute to virulence of P. cichorii SF1-54 on lettuce. PMID:25961750

  4. Enhanced plasmonic properties of gold-catalysed semiconductor nanowires

    Science.gov (United States)

    Naumenko, Denys; Zannier, Valentina; Grillo, Vincenzo; Cassese, Damiano; Priante, Giacomo; Dal Zilio, Simone; Rubini, Silvia; Lazzarino, Marco

    2014-10-01

    A key challenge for the development of plasmonic nanodevices is their integration into active semiconducting structures. Gold-catalysed semiconductor nanowires are promising candidates for their bottom-up growth process that aligns a single gold nanoparticle at each nanowire apex. Unfortunately these show extremely poor plasmonic properties. In this work, we propose a way to enhance their plasmonic resonance up to those of ideal and isolated gold nanoparticles. A suitable purification protocol compatible with GaAs and ZnSe molecular beam epitaxy of nanowires is used to produce plasmonic active nanowires, which were used to enhance the Raman signal of pentacene and graphene oxide. Enhancement factors up to three orders of magnitude are demonstrated.A key challenge for the development of plasmonic nanodevices is their integration into active semiconducting structures. Gold-catalysed semiconductor nanowires are promising candidates for their bottom-up growth process that aligns a single gold nanoparticle at each nanowire apex. Unfortunately these show extremely poor plasmonic properties. In this work, we propose a way to enhance their plasmonic resonance up to those of ideal and isolated gold nanoparticles. A suitable purification protocol compatible with GaAs and ZnSe molecular beam epitaxy of nanowires is used to produce plasmonic active nanowires, which were used to enhance the Raman signal of pentacene and graphene oxide. Enhancement factors up to three orders of magnitude are demonstrated. Electronic supplementary information (ESI) available: SEM characterization of: (i) transferred ZnSe NWs onto the glass substrates, (ii) etched gold NPs of ZnSe NWs in Ar+ plasma, and (iii) self-catalysed GaAs NWs. Simulation of extinction spectra. Statistical characterization of plasmon-active sites at the focal plane with a length of NWs. Photoluminescence on ZnSe NWs. B3g Raman mode of pentacene as an indicator of molecule orientation. The dependence of graphene oxide Raman

  5. Exotic Grazing Resonances in Nanowires

    CERN Document Server

    Feng, Simin

    2009-01-01

    We investigate electromagnetic scattering from nanoscale wires and reveal for the first time, the emergence of a family of exotic resonances, or enhanced fields, for source waves close to grazing incidence. These grazing resonances can have a much higher Q factor, broader bandwidth, and are much less susceptible to material losses than the well known surface plasmon resonances found in metal nanowires. Contrary to surface plasmon resonances however, these grazing resonances can be excited in both dielectric and metallic nanowires and are insensitive to the polarization state of the incident wave. This peculiar resonance effect originates from the excitation of long range guided surface waves through the interplay of coherently scattered continuum modes coupled with the azimuthal first order propagating mode of the cylindrical nanowire. The nanowire resonance phenomenon revealed here can be utilized in broad scientific areas, including: metamaterial designs, nanophotonic integration, nanoantennas, and nanosens...

  6. Electric Conductivity of Phosphorus Nanowires

    International Nuclear Information System (INIS)

    We present the structures and electrical transport properties of nanowires made from different strands of phosphorus chains encapsulated in carbon nanotubes. Optimized by density function theory, our results indicate that the conductance spectra reveal an oscillation dependence on the size of wires. It can be seen from the density of states and current-voltage curves that the structure of nanowires affects their properties greatly. Among them, the DNA-like double-helical phosphorus nanowire exhibits the distinct characteristic of an approximately linear I – V relationship and has a higher conductance than others. The transport properties of phosphorus nanowires are highly correlated with their microstructures. (condensed matter: structure, mechanical and thermal properties)

  7. Thermal Conductivity of Segmented Nanowires

    OpenAIRE

    Denis L. Nika; Cocemasov, Aleksandr I.; Balandin, Alexander A.

    2016-01-01

    We present a review of the phonon thermal conductivity of segmented nanowires focusing on theoretical results for Si and Si/Ge structures with the constant and periodically modulated cross-sections. We describe the use of the face-centered cubic cell and Born-von Karman models of the lattice vibrations for calculating the phonon energy spectra in the segmented nanowires. Modification of the phonon spectrum in such nanostructures results in strong reduction of the phonon thermal conductivity a...

  8. Quantum transport in semiconductor nanowires

    OpenAIRE

    Van Dam, J.

    2006-01-01

    This thesis describes a series of experiments aimed at understanding the low-temperature electrical transport properties of semiconductor nanowires. The semiconductor nanowires (1-100 nm in diameter) are grown from nanoscale gold particles via a chemical process called vapor-liquid-solid (VLS) growth. The huge versatility of this material system (e.g. in size and materials) results in a wide range of potential applications in (opto-)electronics. During the last few years many important proofs...

  9. Fabrication of nanowires and nanostructures

    DEFF Research Database (Denmark)

    Mátéfi-Tempfli, Stefan; Mátéfi-Tempfli, M.; Piraux, L.

    2009-01-01

    We report on different approaches that we have adopted and developed for the fabrication of nanowires and nanostructures. Methods based on template synthesis and on self organization seem to be the most promising for the fabrication of nanomaterials and nanostructures due to their easiness and low...... with microelectronic processes make it an ideal candidate for further integration into large-scale fabrication of various nanowire-based devices. © 2009 Springer-Verlag....

  10. Shewanella oneidensis MR-1 Nanowires are Outer Membrane and Periplasmic Extensions of the Extracellular Electron Transport Components

    Energy Technology Data Exchange (ETDEWEB)

    Pirbadian, S.; Barchinger, S. E.; Leung, K. M.; Byun, H. S.; Jangir, Y.; Bouhenni, Rachida; Reed, Samantha B.; Romine, Margaret F.; Saffarini, Daad; Shi, Liang; Gorby, Yuri A.; Golbeck, J. H.; El-Naggar, Mohamed Y.

    2014-08-20

    Bacterial nanowires offer an extracellular electron transport (EET) pathway for linking the respiratory chain of bacteria to external surfaces, including oxidized metals in the environment and engineered electrodes in renewable energy devices. Despite the global, environmental, and technological consequences of this biotic-abiotic interaction, the composition, physiological relevance, and electron transport mechanisms of bacterial nanowires remain unclear. We report the first in vivo observations of the formation and respiratory impact of nanowires in the model metal-reducing microbe Shewanella neidensis MR-1. Using live fluorescence measurements, immunolabeling, and quantitative gene expression analysis, we report that S. oneidensis MR-1 nanowires are extensions of the outer membrane and periplasm that include the multiheme cytochromes responsible for EET, rather than pilin-based structures, as previously thought. These bacterial nanowires were also associated with outer membrane vesicles and vesicle chains, structures ubiquitous in gram-negative bacteria. Redoxfunctionalized membrane and vesicular extensions may represent a general microbial strategy for electron transport and energy distribution.

  11. Magnetic properties of electrodeposited nanowires

    Science.gov (United States)

    Heydon, G. P.; Hoon, S. R.; Farley, A. N.; Tomlinson, S. L.; Valera, M. S.; Attenborough, K.; Schwarzacher, W.

    1997-04-01

    Electrodeposited multilayered nanowires grown within a polycarbonate membrane constitute a new medium in which giant magnetoresistance (GMR) perpendicular to the plane of the multilayers can be measured. These structures can exhibit a perpendicular GMR of at least 22% at ambient temperature. We performed detailed studies both of reversible magnetization and of irreversible remanent magnetization curves for CoNiCu/Cu/CoNiCu multilayered and CoNiCu pulse-deposited nanowire systems with Co:Ni ratios of 6:4 and 7:3 respectively in the range 10 - 290 K, allowing the magnetic phases of these structures to be identified. Shape anisotropy in the pulse-deposited nanowire and inter-layer coupling in the multilayered nanowire are shown to make important contributions to the magnetic properties. Dipolar-like interactions are found to predominate in both nanowire systems. Magnetic force microscope (MFM) images of individual multilayered nanowires exhibit a contrast consistent with there being a soft magnetization parallel to the layers. Switching of the magnetic layers in the multilayered structure into the direction of the MFM tip's stray field is observed.

  12. Photoenhanced Patterning of Metal Nanowire Networks for Fabrication of Ultraflexible Transparent Devices.

    Science.gov (United States)

    Song, Chang-Hyun; Han, Chul Jong; Ju, Byeong-Kwon; Kim, Jong-Woong

    2016-01-13

    Network structures of metal nanowires are a promising candidate for producing a wide range of flexible electronic devices, but only if they can be suitably patterned and retained on various materials. Here we present a new approach to the patterning of metal nanowires by employing intense-pulsed-light (IPL) irradiation to reduce the process to just two steps: irradiation and the subsequent removal of nonirradiated nanowires. This ultrasimple method eliminates the need to employ chemical reagents for etching or improving the adhesion of nanowires, and is compatible with Ag nanowires (AgNWs), Cu nanowires (CuNWs), and most transparent polymers. Furthermore, it is not reliant on additional processes, such as coating, heating, developing, and etching to make a patterned nanowire structure. Using this simple method, ultraflexible and transparent devices such as touch sensor, heater and light emitting diode with an exceptionally high mechanical stability have been successfully fabricated. This new method is expected to be directly applicable to the fabrication of a wide range of high-performance, low-cost, biocompatible, and wearable devices. PMID:26690092

  13. Room-temperature solution synthesis of Ag nanoparticle functionalized molybdenum oxide nanowires and their catalytic applications

    International Nuclear Information System (INIS)

    A simple chemical solution route for the synthesis of large-scale high-quality Ag nanoparticle functionalized molybdenum oxide nanowire at room temperature has been developed. In the synthesis, the protonated amine was intercalated into the molybdenum bronze layers to reduce the electrostatic force of the lamellar structures, and then the Ag nanoparticle functionalized long nanowires could be easily induced by a redox reaction between a molybdenum oxide–amine intermediate and Ag+ at room temperature. The intercalation lamellar structures improved the nucleation and growth of the Ag nanoparticles, with the result that uniform Ag nanoparticles occurred on the surface of the MoO3 nanowire. In this way Ag nanoparticles with average sizes of around 6 nm, and high-purity nanowires with mean diameter of around 50 nm and with typical lengths of several tens to hundreds of micrometers were produced. The heteronanostructured nanowires were intricately and inseparably connected to each other with hydrogen bonds and/or bridge oxygen atoms and packed together, forming a paper-like porous network film. The Ag–MoO3 nanowire film performs a promoted catalytic property for the epoxidation of cis-cyclooctene, and the heteronanostructured nanowire film sensor shows excellent sensing performance to hydrogen and oxygen at room temperature. (paper)

  14. Improvement of electron transport in a ZnSe nanowire by in situ strain

    International Nuclear Information System (INIS)

    Strain is introduced in a single ZnSe nanowire by compressive stress in situ applied along the axial direction, which controllably bends the nanowire under transmission electron microscope inspection. Meanwhile, the I-V measurement of a single ZnSe nanowire before and after the strain is carried out in order to investigate the influence of strain on the electrical properties of the individual ZnSe nanowire. A remarkable jump of about 100% in current and a reduction of about 30% in threshold voltage are detected when the stress is applied along the longitudinal direction of the nanowire. The advantage of stress-induced strains is to produce both compression and tension simultaneously in a single nanowire, which enhance the electron and hole mobilities and significantly improve the electron transport as a consequence. Narrowing the band gap due to the tensile strain, confirmed by theoretical calculation, is responsible for the reduction of threshold voltage. The stress-induced strains in the ZnSe nanowire are favourable for optimization of the carrier transport.

  15. Rapid large-scale preparation of ZnO nanowires for photocatalytic application

    Directory of Open Access Journals (Sweden)

    Wang Zhiming

    2011-01-01

    Full Text Available Abstract ZnO nanowires are a promising nanomaterial for applications in the fields of photocatalysis, nano-optoelectronics, and reinforced composite materials. However, the challenge of producing large-scale ZnO nanowires has stunted the development and practical utilization of ZnO nanowires. In this study, a modified carbothermal reduction method for preparing large-scale ZnO nanowires in less than 5 min is reported. The preparation was performed in a quartz tube furnace at atmospheric pressure without using any catalysts. A mixed gas of air and N2 with a volume ratio of 45:1 was used as the reactive and carrier gas. About 0.8 g ZnO nanowires was obtained using 1 g ZnO and 1 g graphite powder as source materials. The obtained nanowires exhibited a hexagonal wurtzite crystal structure with an average diameter of about 33 nm. Good photocatalytic activity of the nanowires toward the photodegradation of methylene blue dye under UV irradiation was also demonstrated.

  16. Transfer, composition and technological characterization of the lactic acid bacterial populations of the wooden vats used to produce traditional stretched cheeses.

    Science.gov (United States)

    Scatassa, Maria Luisa; Gaglio, Raimondo; Macaluso, Giusi; Francesca, Nicola; Randazzo, Walter; Cardamone, Cinzia; Di Grigoli, Antonino; Moschetti, Giancarlo; Settanni, Luca

    2015-12-01

    The biofilms of 12 wooden vats used for the production of the traditional stretched cheeses Caciocavallo Palermitano and PDO Vastedda della valle del Belìce were investigated. Salmonella spp. and Listeria monocytogenes were never detected. Total coliforms were at low numbers with Escherichia coli found only in three vats. Coagulase-positive staphylococci (CPS) were below the enumeration limit, whereas lactic acid bacteria (LAB) dominated the surfaces of all vats. In general, the dominance was showed by coccus LAB. Enterococci were estimated at high numbers, but usually between 1 and 2 Log cycles lower than other LAB. LAB populations were investigated at species and strain level and for their technological properties relevant in cheese production. Eighty-five strains were analysed by a polyphasic genetic approach and allotted into 16 species within the genera Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Pediococcus and Streptococcus. Enterococcus faecium was found in all wooden vats and the species most frequently isolated were Enterococcus faecalis, Lactococcus lactis, Leuconostoc mesenteroides, Pediococcus acidilactici and Streptococcus thermophilus. The study of the quantitative data on acidification rate, autolysis kinetics, diacetyl production, antibacterial compound generation and proteolysis by cluster and principal component analysis led to the identification of some strains with promising dairy characteristics. Interestingly, a consistent percentage of LAB was bacteriocin-like inhibitory substances (BLIS) producer. Thus, the microbial biofilms of the wooden vats analysed in this study might contribute actively to the stability of the final cheeses. PMID:26338114

  17. Metal-conductive polymer hybrid nanostructures: preparation and electrical properties of palladium-polyimidazole nanowires

    Science.gov (United States)

    Al-Hinai, Mariam; Hassanien, Reda; Watson, Scott M. D.; Wright, Nicholas G.; Houlton, Andrew; Horrocks, Benjamin R.

    2016-03-01

    A simple, convenient method for the formation of hybrid metal/conductive polymer nanostructures is described. Polyimidazole (PIm) has been templated on λ-DNA via oxidative polymerisation of imidazole using FeCl3 to produce conductive PIm/DNA nanowires. The PIm/DNA nanowires were decorated with Pd (Pd/PIm/DNA) by electroless reduction of {{{{PdCl}}}4}2- with NaBH4 in the presence of PIm/DNA; the choice of imidazole was motivated by the potential Pd(II) binding site at the pyridinic N atom. The formation of PIm/DNA and the presence of metallic Pd on Pd/PIm/DNA nanowires were verified by FTIR, UV-vis and XPS spectroscopy techniques. AFM studies show that the nanowires have diameters in the range 5-45 nm with a slightly greater mean diameter (17.1 ± 0.75 nm) for the Pd-decorated nanowires than the PIm/DNA nanowires (14.5 ± 0.89 nm). After incubation for 24 h in the polymerisation solution, the PIm/DNA nanowires show a smooth, uniform morphology, which is retained after decoration with Pd. Using a combination of scanned conductance microscopy, conductive AFM and two-terminal measurements we show that both types of nanowire are conductive and that it is possible to discriminate different possible mechanisms of transport. The conductivity of the Pd/PIm/DNA nanowires, (0.1-1.4 S cm-1), is comparable to the PIm/DNA nanowires (0.37 ± 0.029 S cm-1). In addition, the conductance of Pd/PIm/DNA nanowires exhibits Arrhenius behaviour (E a = 0.43 ± 0.02 eV) as a function of temperature in contrast to simple Pd/DNA nanowires. These results indicate that although the Pd crystallites on Pd/PIm/DNA nanowires decorate the PIm polymer, the major current pathway is through the polymer rather than the Pd.

  18. Structural and tunneling properties of Si nanowires

    KAUST Repository

    Montes, E.

    2013-12-06

    We investigate the electronic structure and electron transport properties of Si nanowires attached to Au electrodes from first principles using density functional theory and the nonequilibrium Green\\'s function method. We systematically study the dependence of the transport properties on the diameter of the nanowires, on the growth direction, and on the length. At the equilibrium Au-nanowire distance we find strong electronic coupling between the electrodes and nanowires, which results in a low contact resistance. With increasing nanowire length we study the transition from metallic to tunneling conductance for small applied bias. For the tunneling regime we investigate the decay of the conductance with the nanowire length and rationalize the results using the complex band structure of the pristine nanowires. The conductance is found to depend strongly on the growth direction, with nanowires grown along the ⟨110⟩ direction showing the smallest decay with length and the largest conductance and current.

  19. Gallium-Catalyzed Silicon Oxide Nanowire Growth

    Institute of Scientific and Technical Information of China (English)

    Zheng Wei Pan; Sheng Dai; Douglas H.Lowndes

    2005-01-01

    Silicon oxide nanowires tend to assemble into various complex morphologies through a metalcatalyzed vapor-liquid-solid (VLS) growth process. This article summarizes our recent efforts in the controlled growth of silicon oxide nanowire assemblies by using molten gallium as the catalyst and silicon wafer,SiO powder, or silane (SiH4) as the silicon sources. Silicon oxide nanowire assemblies with morphologies of carrotlike, cometlike, gourdlike, spindlelike, badmintonlike, sandwichlike, etc. were obtained. Although the morphologies of the nanowire assemblies are temperature- and silicon source-dependent, they share similar structural and compositional features: all the assemblies contain a microscale spherical liquid Ga ball and a highly aligned, closely packed amorphous silicon oxide nanowire bunch. The Ga-catalyzed silicon oxide nanowire growth reveals several interesting new nanowire growth phenomena that expand our knowledge of the conventional VLS nanowire growth mechanism.

  20. Electrochemical synthesis of highly crystalline copper nanowires

    International Nuclear Information System (INIS)

    Copper nanowires were fabricated within the pores of anodic alumina template (AAT) by template synthesis method at pH = 2.9. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to investigate the structure, morphology and composition of fabricated nanowires. These characterizations revealed that the deposited copper nanowires were highly crystalline in nature, dense and uniform. The crystalline copper nanowires are promising in application of future nanoelectronic devices and circuits

  1. Surfactant-Templated Mesoporous Metal Oxide Nanowires

    OpenAIRE

    Hongmei Luo; Qianglu Lin; Stacy Baber; Mahesh Naalla

    2010-01-01

    We demonstrate two approaches to prepare mesoporous metal oxide nanowires by surfactant assembly and nanoconfinement via sol-gel or electrochemical deposition. For example, mesoporous Ta2O5 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 sca...

  2. Electrochemical synthesis of highly crystalline copper nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Amandeep [Department of Electronics and Communication Engineering, Punjabi University, Patiala 147 002, Punjab (India); Gupta, Tanish; Kumar, Akshay [Department of Nanotechnology, SGGSW University, Fatehgarh Sahib 140406, Punjab (India); Kumar, Sanjeev [Department of Applied Sciences, PEC University of Technology, Chandigarh 160012 (India); Singh, Karamjeet [Department of Physics, Punjabi University, Patiala 147002, Punjab (India); Thakur, Anup, E-mail: dranupthakur@gmail.com [Advanced Materials Research Lab, Department of Basic and Applied Sciences, Punjabi University, Patiala 147 002, Punjab (India)

    2015-05-15

    Copper nanowires were fabricated within the pores of anodic alumina template (AAT) by template synthesis method at pH = 2.9. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to investigate the structure, morphology and composition of fabricated nanowires. These characterizations revealed that the deposited copper nanowires were highly crystalline in nature, dense and uniform. The crystalline copper nanowires are promising in application of future nanoelectronic devices and circuits.

  3. Semiconducting silicon nanowires for biomedical applications

    CERN Document Server

    Coffer, JL

    2014-01-01

    Biomedical applications have benefited greatly from the increasing interest and research into semiconducting silicon nanowires. Semiconducting Silicon Nanowires for Biomedical Applications reviews the fabrication, properties, and applications of this emerging material. The book begins by reviewing the basics, as well as the growth, characterization, biocompatibility, and surface modification, of semiconducting silicon nanowires. It goes on to focus on silicon nanowires for tissue engineering and delivery applications, including cellular binding and internalization, orthopedic tissue scaffol

  4. An optically guided microdevice comprising a nanowire

    DEFF Research Database (Denmark)

    2014-01-01

    three axes, is possible. The microdevice further comprises a nanowire (150) being arranged for emitting electromagnetic radiation onto said associated object. This is advantageous for obtaining better spatial control of the microdevice comprising the nanowire, and this enables that light could more...... effectively be coupled into the nanowire. This opens up for a much wider application of nanowires in optics because of the improved spatial control....

  5. Optical properties of nanowire metamaterials with gain

    DEFF Research Database (Denmark)

    Isidio de Lima, Joaquim Junior; Adam, Jost; Rego, Davi;

    2016-01-01

    The transmittance, reflectance and absorption of a nanowire metamaterial with optical gain are numerically simulated and investigated. It is assumed that the metamaterial is represented by aligned silver nanowires embedded into a semiconductor matrix, made of either silicon or gallium phosphide...... constant of the metamaterial. This peculiar behavior is explained by the field redistribution between the lossy metal nanowires and the amplifying matrix material. These findings are significant for a proper design of nanowire metamaterials with low optical losses for diverse applications....

  6. Controlling nanowire emission profile using conical taper

    DEFF Research Database (Denmark)

    Gregersen, Niels; Nielsen, Torben Roland; Mørk, Jesper;

    2008-01-01

    The influence of a conical taper on nanowire light emission is studied. For nanowires with divergent output beams, the introduction of tapers improves the emission profile and increase the collection efficiency of the detection optics.......The influence of a conical taper on nanowire light emission is studied. For nanowires with divergent output beams, the introduction of tapers improves the emission profile and increase the collection efficiency of the detection optics....

  7. Inorganic nanowires applications, properties, and characterization

    CERN Document Server

    Meyyappan, M

    2009-01-01

    IntroductionHistorical Perspective Growth TechniquesLiquid-Phase TechniquesVapor-Phase TechniquesBulk Production MethodsFuture Developments Thermodynamic and Kinetic Aspects of Nanowire GrowthThermodynamic Considerations for Vapor-Liquid-Solid GrowthKinetic Considerations of Nanowire Growth Under VLS Growth Modeling of Nanowire GrowthEnergetics of Stable Surface Face

  8. Fabrication of ZnO Nanowires Arrays by Anodization and High-Vacuum Die Casting Technique, and Their Piezoelectric Properties.

    Science.gov (United States)

    Kuo, Chin-Guo; Chang, Ho; Wang, Jian-Hao

    2016-01-01

    In this investigation, anodic aluminum oxide (AAO) with arrayed and regularly arranged nanopores is used as a template in the high-vacuum die casting of molten zinc metal (Zn) into the nanopores. The proposed technique yields arrayed Zn nanowires with an aspect ratio of over 600. After annealing, arrayed zinc oxide (ZnO) nanowires are obtained. Varying the anodizing time yields AAO templates with thicknesses of approximately 50 μm, 60 μm, and 70 μm that can be used in the fabrication of nanowires of three lengths with high aspect ratios. Experimental results reveal that a longer nanowire generates a greater measured piezoelectric current. The ZnO nanowires that are fabricated using an alumina template are anodized for 7 h and produce higher piezoelectric current of up to 69 pA. PMID:27023546

  9. Fabrication of ZnO Nanowires Arrays by Anodization and High-Vacuum Die Casting Technique, and Their Piezoelectric Properties

    Directory of Open Access Journals (Sweden)

    Chin-Guo Kuo

    2016-03-01

    Full Text Available In this investigation, anodic aluminum oxide (AAO with arrayed and regularly arranged nanopores is used as a template in the high-vacuum die casting of molten zinc metal (Zn into the nanopores. The proposed technique yields arrayed Zn nanowires with an aspect ratio of over 600. After annealing, arrayed zinc oxide (ZnO nanowires are obtained. Varying the anodizing time yields AAO templates with thicknesses of approximately 50 μm, 60 μm, and 70 μm that can be used in the fabrication of nanowires of three lengths with high aspect ratios. Experimental results reveal that a longer nanowire generates a greater measured piezoelectric current. The ZnO nanowires that are fabricated using an alumina template are anodized for 7 h and produce higher piezoelectric current of up to 69 pA.

  10. Bacterial Vaginosis

    Science.gov (United States)

    ... 586. Related Content STDs during Pregnancy Fact Sheet Pregnancy and HIV, Viral Hepatitis, and STD Prevention Pelvic Inflammatory Disease ( ... Bacterial Vaginosis (BV) Chlamydia Gonorrhea Genital Herpes Hepatitis HIV/AIDS & STDs Human Papillomavirus ... STDs See Also Pregnancy Reproductive ...

  11. Bacterial Meningitis

    Science.gov (United States)

    ... Schedules Preteen & Teen Vaccines Meningococcal Disease Sepsis Bacterial Meningitis Recommend on Facebook Tweet Share Compartir On this ... serious disease. Laboratory Methods for the Diagnosis of Meningitis This manual summarizes laboratory methods used to isolate, ...

  12. Prostatitis - bacterial

    Science.gov (United States)

    Any bacteria that can cause a urinary tract infection can cause acute bacterial prostatitis. Infections spread through sexual contact can cause prostatitis. These include chlamydia and gonorrhea . Sexually transmitted ...

  13. Bacterial Conjunctivitis

    OpenAIRE

    Köhle, Ülkü; Kükner, Şahap

    2003-01-01

    Conjunctivitis is an infection of the conjunctiva, generally characterized by irritation, itching, foreign body sensation, tearing and discharge. Bacterial conjunctivitis may be distinguished from other types of conjunctivitis by the presence of yellow–white mucopurulent discharge. It is the most common form of ocular infection all around the world. Staphylococcus species are the most common bacterial pathogenes, followed by Streptococcus pneumoniae and Haemophilus i...

  14. Fabrication of cobalt nanowires from mixture of 1-ethyl-3-methylimidazolium chloride ionic liquid and ethylene glycol using porous anodic alumina template

    International Nuclear Information System (INIS)

    Porous anodic alumina template is synthesized by electrochemical anodization of aluminum and used to grow cobalt nanowires. The cobalt nanowires produced by direct current electrodeposition are characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction and physical property measurement system. Test results indicate that the average diameter of cobalt nanowires is about 45 nm, which is generally the same as the pore diameter of porous anodic alumina template, and the cobalt nanowires electrodeposited from mixture of 1-ethyl-3-methylimidazolium chloride ionic liquid and ethylene glycol have a smoother surface and better magnetic properties than cobalt nanowires electrodeposited from aqueous solution, and they show a better squareness. Therefore it can be concluded that the cobalt nanowires electrodeposited from mixture of 1-ethyl-3-methylimidazolium chloride ionic liquid and ethylene glycol using porous anodic alumina template can be used as a perpendicular magnetic recording film

  15. Arrays of TiO2 Nanowires as Photoelectrochemical Sensors for Hydrazine Detection

    Directory of Open Access Journals (Sweden)

    Michael Ongaro

    2015-05-01

    Full Text Available Electrodes based on arrays of TiO2 nanowires were prepared by template sol-gel synthesis with the goal of developing a hydrazine photoelectrochemical sensor. Experimental conditions were chosen so that the gelation reaction occurred inside the nanopores of track-etched polycarbonate membranes, with consequent filling with TiO2 nanowires. Different procedures for the removal of the template were examined, in order to obtain arrays of self-standing TiO2 nanowires. The nanowire arrays were bound to fluorine doped tin oxide substrates to produce handy photoelectrodes. The photocurrent recorded with the photoelectrodes in the presence of hydrazine showed significant dependence on the pollutant concentration. The development of a photoelectrochemical sensor for hydrazine detection in water samples, based on this principle, is presented.

  16. In-plane trapping and manipulation of ZnO nanowires by a hybrid plasmonic field

    Science.gov (United States)

    Zhang, Lichao; Dou, Xiujie; Min, Changjun; Zhang, Yuquan; Du, Luping; Xie, Zhenwei; Shen, Junfeng; Zeng, Yujia; Yuan, Xiaocong

    2016-05-01

    In general, when a semiconductor nanowire is trapped by conventional laser beam tweezers, it tends to be aligned with the trapping beam axis rather than confined in the horizontal plane, and this limits the application of these nanowires in many in-plane nanoscale optoelectronic devices. In this work, we achieve the in-plane trapping and manipulation of a single ZnO nanowire by a hybrid plasmonic tweezer system on a flat metal surface. The gap between the nanowire and the metallic substrate leads to an enhanced gradient force caused by deep subwavelength optical energy confinement. As a result, the nanowire can be securely trapped in-plane at the center of the excited surface plasmon polariton field, and can also be dynamically moved and rotated by varying the position and polarization direction of the incident laser beam, which cannot be performed using conventional optical tweezers. The theoretical results show that the focused plasmonic field induces a strong in-plane trapping force and a high rotational torque on the nanowire, while the focused optical field produces a vertical trapping force to produce the upright alignment of the nanowire; this is in good agreement with the experimental results. Finally, some typical ZnO nanowire structures are built based on this technique, which thus further confirms the potential of this method for precise manipulation of components during the production of nanoelectronic and nanophotonic devices.In general, when a semiconductor nanowire is trapped by conventional laser beam tweezers, it tends to be aligned with the trapping beam axis rather than confined in the horizontal plane, and this limits the application of these nanowires in many in-plane nanoscale optoelectronic devices. In this work, we achieve the in-plane trapping and manipulation of a single ZnO nanowire by a hybrid plasmonic tweezer system on a flat metal surface. The gap between the nanowire and the metallic substrate leads to an enhanced gradient force

  17. ZrTiO4 nanowire growth using membrane-assisted Pechini route

    Directory of Open Access Journals (Sweden)

    P. R. de Lucena

    2014-11-01

    Full Text Available The high surface-to-volume ratio of nanowires makes them natural competitors as new device components. In this regard, a current major challenge is to produce quasi-one-dimensional nanostructures composed of well established oxide-based materials. This article reports the synthesis of ZrTiO4 nanowires on a silicon (100 wafer in a single-step deposition/thermal treatment. The template-directed membrane synthesis strategy was associated with the Pechini route and spin-coating deposition technique. ZrTiO4 nanowires were obtained at 700 ˚C with diameters in the range of 80-100 nm. FEG- SEM images were obtained to investigate ZrTiO4 nanowire formation on the silicon surface and energy dispersive x-ray detection (EDS and x-ray diffraction (XRD analyses were performed to confirm the oxide composition and structure.

  18. Plasmonic Properties of Vertically Aligned Nanowire Arrays

    Directory of Open Access Journals (Sweden)

    Hua Qi

    2012-01-01

    Full Text Available Nanowires (NWs/Ag sheath composites were produced to investigate plasmonic coupling between vertically aligned NWs for surface-enhanced Raman scattering (SERS applications. In this investigation, two types of vertical NW arrays were studied; those of ZnO NWs grown on nanosphere lithography patterned sapphire substrate via vapor-liquid-solid (VLS mechanism and Si NW arrays produced by wet chemical etching. Both types of vertical NW arrays were coated with a thin layer of silver by electroless silver plating for SERS enhancement studies. The experimental results show extremely strong SERS signals due to plasmonic coupling between the NWs, which was verified by COMSOL electric field simulations. We also compared the SERS enhancement intensity of aligned and random ZnO NWs, indicating that the aligned NWs show much stronger and repeatable SERS signal than those grown in nonaligned geometries.

  19. Bacterial Alkaloids Prevent Amoebal Predation.

    Science.gov (United States)

    Klapper, Martin; Götze, Sebastian; Barnett, Robert; Willing, Karsten; Stallforth, Pierre

    2016-07-25

    Bacterial defense mechanisms have evolved to protect bacteria against predation by nematodes, predatory bacteria, or amoebae. We identified novel bacterial alkaloids (pyreudiones A-D) that protect the producer, Pseudomonas fluorescens HKI0770, against amoebal predation. Isolation, structure elucidation, total synthesis, and a proposed biosynthetic pathway for these structures are presented. The generation of P. fluorescens gene-deletion mutants unable to produce pyreudiones rendered the bacterium edible to a variety of soil-dwelling amoebae. PMID:27294402

  20. Gold nanowires and the effect of impurities

    Directory of Open Access Journals (Sweden)

    Novaes Frederico

    2006-01-01

    Full Text Available AbstractMetal nanowires and in particular gold nanowires have received a great deal of attention in the past few years. Experiments on gold nanowires have prompted theory and simulation to help answer questions posed by these studies. Here we present results of computer simulations for the formation, evolution and breaking of very thin Au nanowires. We also discuss the influence of contaminants, such as atoms and small molecules, and their effect on the structural and mechanical properties of these nanowires.

  1. Micromagnetic simulations of cylindrical magnetic nanowires

    KAUST Repository

    Ivanov, Yurii P.

    2015-05-27

    This chapter reviews micromagnetic simulations of cylindrical magnetic nanowires and their ordered arrays. It starts with a description of the theoretical background of micromagnetism. The chapter discusses main magnetization reversal modes, domain wall types, and state diagrams in cylindrical nanowires of different types and sizes. The results of the hysteresis process in individual nanowires and nanowire arrays also are presented. Modeling results are compared with experimental ones. The chapter also discusses future trends in nanowire applications in relation to simulations, such as current-driven dynamics, spintronics, and spincaloritronics. The main micromagnetic programs are presented and discussed, together with the corresponding links.

  2. Mapping the local structure of nanowires

    DEFF Research Database (Denmark)

    Persson, Johan Mikael; Wagner, Jakob Birkedal

    2013-01-01

    The crystallographic and compositional structure of heterostructured semiconductor nanowires has been studied by means of transmission electron microscopy. The native geometry of the studied InP-GaAs nanowires (80-100 nm in diameter) is in general too thick for reliable high-resolution TEM imaging....... Nano Beam Electron Diffraction (NBED) is shown to be a powerful technique to reveal strain near the interface of compositional change in heterostructured semiconductor nanowires. Furthermore, the relative orientation of the nanowires is studied by means of NBED revealing the nanowires to be very...

  3. Stacking faults in SiC nanowires.

    Science.gov (United States)

    Wallis, K L; Wieligor, M; Zerda, T W; Stelmakh, S; Gierlotka, S; Palosz, B

    2008-07-01

    SiC nanowires were obtained by a reaction between vapor silicon and multiwall carbon nanotubes, CNT, in vacuum at 1200 degrees C. Raman and IR spectrometry, X-ray diffraction and high resolution transmission electron microscopy, HRTEM, were used to characterize properties of SiC nanowires. Morphology and chemical composition of the nanowires was similar for all samples, but concentration of structural defects varied and depended on the origin of CNT. Stacking faults were characterized by HRTEM and Raman spectroscopy, and both techniques provided complementary results. Raman microscopy allowed studying structural defects inside individual nanowires. A thin layer of amorphous silicon carbide was detected on the surface of nanowires. PMID:19051903

  4. Magnetic resonance characterization of silicon nanowires

    Science.gov (United States)

    Fanciulli, Marco; Belli, Matteo; Vellei, Antonio; Canevali, Carmen; Rotta, Davide; Paleari, Stefano; Basini, Martina

    2012-02-01

    Silicon nanowires (SiNWs) have been extensively investigated in the last decades. The interest in these nanostructures stems from both fundamental and applied research motivations. The functional properties of one- and zero-dimensional silicon structures are significantly different, at least below a certain critical dimension, from those well known in the bulk. The key and peculiar functional properties of SiNWs find applications in nanoelectronics, classical and quantum information processing and storage, optoelectronics, photovoltaics, thermoelectric, battery technology, nano-biotechnology, and neuroelectronics. We report our work on the characterization by continuous wave (CW) and pulse electron spin resonance (CW, FT-EPR) and electrically detected magnetic resonance (EDMR) measurements of silicon nanowires (SiNWs) produced by different top-down processes. SiNWs were fabricated starting from SOI wafers using standard e-beam lithography and anisotropic wet etching or by metal-assisted chemical etching. Further oxidation was used to reduce the wire cross section. Different EDMR implementations were used to address the electronic wave function of donors (P, As) and to characterize point defects at the SiNWs/SiO2 interface.

  5. Electrically Injected UV-Visible Nanowire Lasers

    Energy Technology Data Exchange (ETDEWEB)

    Wang, George T.; Li, Changyi; Li, Qiming; Liu, Sheng; Wright, Jeremy Benjamin; Brener, Igal; Luk, Ting -Shan; Chow, Weng W.; Leung, Benjamin; Figiel, Jeffrey J.; Koleske, Daniel D.; Lu, Tzu-Ming

    2015-09-01

    There is strong interest in minimizing the volume of lasers to enable ultracompact, low-power, coherent light sources. Nanowires represent an ideal candidate for such nanolasers as stand-alone optical cavities and gain media, and optically pumped nanowire lasing has been demonstrated in several semiconductor systems. Electrically injected nanowire lasers are needed to realize actual working devices but have been elusive due to limitations of current methods to address the requirement for nanowire device heterostructures with high material quality, controlled doping and geometry, low optical loss, and efficient carrier injection. In this project we proposed to demonstrate electrically injected single nanowire lasers emitting in the important UV to visible wavelengths. Our approach to simultaneously address these challenges is based on high quality III-nitride nanowire device heterostructures with precisely controlled geometries and strong gain and mode confinement to minimize lasing thresholds, enabled by a unique top-down nanowire fabrication technique.

  6. Nonlinear optics with ZnO nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Voss, Tobias; Kudyk, Iryna; Wischmeier, Lars; Gutowski, Juergen [Institute of Solid State Physics, University of Bremen (Germany)

    2009-02-15

    Second-harmonic generation and two-photon induced photoluminescence from arrays of ZnO nanowires and single nanowires under excitation with femtosecond pulses is experimentally studied. The ratio of relevant components of the nonlinear {chi}{sup (2)} tensor is obtained. The excitation of the nanowire array with femtosecond laser pulses induces significant heating of the free-standing nanowires. The heat distribution is analyzed in phenomenological finite-element studies. Two-photon excitation of a broad internal photoluminescence in single ZnO nanowires is used to perform a single-nanowire transmission experiment. From the transmitted intensity, the band-gap shift in the excited nanowire is obtained. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Downsizing of single crystalline high aspect ratio tungsten nanowires

    International Nuclear Information System (INIS)

    Directional solidification of eutectic NiAl-W alloys offers an intuitive method to produce tungsten nanowires. Through the use of two different methods, the well-established Bridgman method and a newer type floating zone method, the direct influence of process parameters, like the withdrawal rate and the temperature gradient, onto the sample microstructure were studied. The sharp temperature gradient, built up using a four mirror system focusing the light emitted by halogen lamps inside the optical floating zone furnace allows producing nanowires with a diameter as small as 75 nm. Differences in the solid/liquid interface morphology depending on the solidification method used are discussed. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Downsizing of single crystalline high aspect ratio tungsten nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Milenkovic, Srdjan [IMDEA Materials Institute, Eric Kandel 2, 28906, Getafe (Spain); Drensler, Stefanie [Institute for Chemical Technology of Inorganic Materials, Johannes Kepler University, Altenberger Str. 69, 4040, Linz (Austria); Hassel, Achim Walter [Institute for Chemical Technology of Inorganic Materials, Johannes Kepler University, Altenberger Str. 69, 4040, Linz (Austria); Christian Doppler Laboratory for Combinatorial Oxide Chemistry, Institute for Chemical Technology of Inorganic Materials, Johannes Kepler University Linz, Altenberger Str. 69, 4040, Linz (Austria)

    2015-06-15

    Directional solidification of eutectic NiAl-W alloys offers an intuitive method to produce tungsten nanowires. Through the use of two different methods, the well-established Bridgman method and a newer type floating zone method, the direct influence of process parameters, like the withdrawal rate and the temperature gradient, onto the sample microstructure were studied. The sharp temperature gradient, built up using a four mirror system focusing the light emitted by halogen lamps inside the optical floating zone furnace allows producing nanowires with a diameter as small as 75 nm. Differences in the solid/liquid interface morphology depending on the solidification method used are discussed. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Critical phenomena in magnetic nanowires.

    Science.gov (United States)

    Kamalakar, M Venkata; Raychaudhuri, A K

    2009-09-01

    In this paper we report the first experimental study of critical phenomena in case of magnetic nanowires of nickel near the ferromagnetic-paramagnetic transition from the electrical transport properties. Nickel nanowire arrays, prepared by potentiostatic electrodeposition of nickel inside pores of nanoporous anodic alumina template were well characterized by X-ray Diffraction, Transmission electron microscopy and Energy dispersive Spectroscopy. Precise electrical resistance measurement of the nanowire arrays of wire diameter 20 nm have been done in the temperature range between 300 K to 700 K. We see a drop in the Curie temperature as observed from the resistivity anomaly. We analyzed the resistance data near the critical region and extracted the critical exponent alpha directly from the resistance. We observed a decrease in the critical part of the resistivity including a decrease in the magnitude of the critical exponent alpha and severe modification in the correction to scaling. PMID:19928208

  10. III-Nitride nanowire optoelectronics

    Science.gov (United States)

    Zhao, Songrui; Nguyen, Hieu P. T.; Kibria, Md. G.; Mi, Zetian

    2015-11-01

    Group-III nitride nanowire structures, including GaN, InN, AlN and their alloys, have been intensively studied in the past decade. Unique to this material system is that its energy bandgap can be tuned from the deep ultraviolet (~6.2 eV for AlN) to the near infrared (~0.65 eV for InN). In this article, we provide an overview on the recent progress made in III-nitride nanowire optoelectronic devices, including light emitting diodes, lasers, photodetectors, single photon sources, intraband devices, solar cells, and artificial photosynthesis. The present challenges and future prospects of III-nitride nanowire optoelectronic devices are also discussed.

  11. Controlled fabrication of nanowire sensors.

    Energy Technology Data Exchange (ETDEWEB)

    Leonard, Francois

    2007-10-01

    We present a simple top down approach based on nanoimprint lithography to create dense arrays of silicon nanowires over large areas. Metallic contacts to the nanowires and a bottom gate allow the operation of the array as a field-effect transistor with very large on/off ratios. When exposed to ammonia gas or cyclohexane solutions containing nitrobenzene or phenol, the threshold voltage of the field-effect transistor is shifted, a signature of charge transfer between the analytes and the nanowires. The threshold voltage shift is proportional to the Hammett parameter and the concentration of the nitrobenzene and phenol analytes. For the liquid analytes considered, we find binding energies of 400 meV, indicating strong physisorption. Such values of the binding energies are ideal for stable and reusable sensors.

  12. Thermal instability of gold nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Karim, Shafqat [Fachbereich Chemie, Marburg University (Germany); Toimil-Molares, Maria E.; Cornelius, Thomas; Neumann, Reinhard [Gesellschaft fuer Schwerionenforschung (GSI), Darmstadt (Germany); Balogh, Adam; Ensinger, Wolfgang [Institute of Materials Science, Darmstadt University of Technology (Germany)

    2007-07-01

    The technological implementation of nanostructures in future nano- and opto-electronic devices requires the capability to withstand elevated temperatures often encountered during routine operation. However, due to their reduced size and high surface to volume ratio, nanowires are expected to display structural and morphological instabilities. The Rayleigh instability concept, introduced to describe the instability of liquid jets, is applied to the fragmentation of metal nanowires during heating. Gold nanowires are electrochemically deposited in etched ion track membranes. After dissolving the template, the wires are put on a substrate and heated to temperatures between 300 and 600 C. The wires decay driven by Rayleigh instability, and the process depends on annealing temperature, wire diameter, and crystallinity. Wires of diameter 20 nm already fragment at 300 C being far below the bulk melting temperature of 1064 C.

  13. Semiconductor nanowires and templates for electronic applications

    Energy Technology Data Exchange (ETDEWEB)

    Ying, Xiang

    2009-07-15

    This thesis starts by developing a platform for the organized growth of nanowires directly on a planar substrate. For this, a method to fabricate horizontal porous alumina membranes is studied. The second part of the thesis focuses on the study of nanowires. It starts by the understanding of the growth mechanisms of germanium nanowires and follows by the structural and electrical properties at the single nanowire level. Horizontally aligned porous anodic alumina (PAA) was used as a template for the nanowire synthesis. Three PAA arrangements were studied: - high density membranes - micron-sized fingers - multi-contacts Membranes formed by a high density of nanopores were obtained by anodizing aluminum thin films. Metallic and semiconducting nanowires were synthesized into the PAA structures via DC deposition, pulsed electro-depostion and CVD growth. The presence of gold, copper, indium, nickel, tellurium, and silicon nanowires inside PAA templates was verified by SEM and EDX analysis. Further, room-temperature transport measurements showed that the pores are completely filled till the bottom of the pores. In this dissertation, single crystalline and core-shell germanium nanowires are synthesized using indium and bismuth as catalyst in a chemical vapor deposition procedure with germane (GeH{sub 4}) as growth precursor. A systematic growth study has been performed to obtain high aspect-ratio germanium nanowires. The influence of the growth conditions on the final morphology and the crystalline structure has been determined via scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). In the case of indium catalyzed germanium nanowires, two different structures were identified: single crystalline and crystalline core-amorphous shell. The preferential growth axis of both kinds of nanowires is along the [110] direction. The occurrence of the two morphologies was found to only depend on the nanowire dimension. In the case of bismuth

  14. Controle biológico da mancha-aquosa do melão por compostos bioativos produzidos por Bacillus spp. Biocontrol of bacterial fruit blotch of melon by bioactive compounds produced by Bacillus spp.

    Directory of Open Access Journals (Sweden)

    Elizama Roza Santos

    2006-09-01

    Full Text Available A mancha-aquosa, causada por Acidovorax avenae subsp. citrulli (Aac causa grandes prejuízos à cultura do melão. O controle dessa doença foi estudado in vivo, com microbiolização de sementes de melão Amarelo infectadas, com líquidos fermentados de Bacillus subtilis R14, B. megaterium pv. cerealis RAB7, B. pumilus C116 e Bacillus sp. MEN2, com e sem células bacterianas. O mecanismo de ação dos isolados foi estudado in vitro pelo método de difusão em ágar e os compostos bioativos parcialmente caracterizados por testes de hemólise e atividade surfactante. Nos testes in vivo, não houve diferença significativa entre os tratamentos com e sem células, indicando que o controle ocorreu devido à presença de compostos bioativos produzidos durante as fermentações. Todos os tratamentos diferiram da testemunha sem diferir entre si (P=0,05%. B. megaterium pv. cerealis RAB7 proporcionou redução da incidência (89,1% e do índice de doença (92,7%, elevou o período de incubação da mancha-aquosa de 9,8 para 11,9 dias e reduziu a AACPD de 3,36 para 0,17. In vitro, todos isolados apresentaram antibiose contra Aac e os compostos bioativos foram parcialmente caracterizados como lipopeptídeos.The bacterial fruit blotch, caused by the bacterium Acidovorax avenae subsp. citrulli (Aac, is responsible for great losses in melon production. The control of this disease was investigated in vivo by treating infected yellow melon seeds with fermented broths of B. subtilis R14, B. megaterium pv. cerealis RAB7, B. pumilus C116 and Bacillus sp. MEN2, with and without bacterial cells. The mechanism of action of the strains was studied in vitro by the agar diffusion technique. The bioactive compounds produced were partially characterized by hemolysis test and surfactant activity. Regarding the tests conducted in vivo there was no statistical difference between the treatments with and without bacterial cells, which indicated that the control was due to the

  15. Synthesis process of nanowired Al/CuO thermite

    OpenAIRE

    Petrantoni, Marine; Rossi, Carole; Conédéra, Véronique; Bourrier, D.; Alphonse, Pierre; Tenailleau, Christophe

    2010-01-01

    Al/CuO nanothermites were fabricated by thermal oxidation of copper layer at 4501C for 5 hand by aluminum thermal evaporation: thermal evaporation allows producing thin layer less than 2 mminsize. The copper has been deposited by electroplating or thermal evaporation depending on the required thickness. The obtained diameter of Al/CuO nanowiresis 150–250nm. Al/CuO nanowires composite were characterized by scanning electronmicroscopy (SEM), X-raydiffraction (XRD), differential scanning calorim...

  16. Optimised quantum hacking of superconducting nanowire single-photon detectors

    OpenAIRE

    Tanner, Michael G.; Makarov, Vadim; Hadfield, Robert H.

    2013-01-01

    We explore bright-light control of superconducting nanowire single-photon detectors (SNSPDs) in the shunted configuration (a practical measure to avoid latching). In an experiment, we simulate an illumination pattern the SNSPD would receive in a typical quantum key distribution system under hacking attack. We show that it effectively blinds and controls the SNSPD. The transient blinding illumination lasts for a fraction of a microsecond and produces several deterministic fake clicks during th...

  17. Single crystalline mesoporous silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Hochbaum, Allon; Dargas, Daniel; Hwang, Yun Jeong; Yang, Peidong

    2009-08-18

    Herein we demonstrate a novel electroless etching synthesis of monolithic, single-crystalline, mesoporous silicon nanowire arrays with a high surface area and luminescent properties consistent with conventional porous silicon materials. The photoluminescence of these nanowires suggest they are composed of crystalline silicon with small enough dimensions such that these arrays may be useful as photocatalytic substrates or active components of nanoscale optoelectronic devices. A better understanding of this electroless route to mesoporous silicon could lead to facile and general syntheses of different narrow bandgap semiconductor nanostructures for various applications.

  18. Metal silicide nanowires

    Science.gov (United States)

    Chen, Lih-Juann; Wu, Wen-Wei

    2015-07-01

    The growth, properties and applications of metal silicide nanowires (NWs) have been extensively investigated. The investigations have led to significant advance in the understanding of one-dimensional (1D) metal silicide systems. For example, CoSi is paramagnetic in bulk form, but ferromagnetic in NW geometry. In addition, the helimagnetic phase and skyrmion state in MnSi are stabilized by NW morphology. The influencing factors on the growth of silicide phase have been elucidated for Ni-Si, Pt-Si, and Mn-Si systems. Promising results were obtained for spintronics, non-volatile memories, field emitter, magnetoresistive sensor, thermoelectric generator and solar cells. However, the main thrust has been in microelectronic devices and integrated circuits. Transistors of world-record small size have been fabricated. Reconfigurable Si NW transistors, dually active Si NW transistors and circuits with equal electron and hole transport have been demonstrated. Furthermore, multifunctional devices and logic gates with undoped Si NWs were reported. It is foreseen that practical applications will be realized in the near future.

  19. 芽孢杆菌动态发酵产细菌纤维素工艺的优化%Optimization of Agitation Fermentation Process of Bacterial Cellulose Pro-duced by Bacillus

    Institute of Scientific and Technical Information of China (English)

    朱宏阳; 冯珊; 杨宏芳; 李泳宁; 林伟铃

    2015-01-01

    The agitation fermentation process of bacterial cellulose (BC) produced by Bacillus amyloliquefaciens ZF-7 was optimized in this study.The effect of agitation conditions such as rotation speed,medium volume,tempera-ture,inoculum volume and culture time on the production of BC pellets and the yield of 0.5cm~0.8cm BC pellets was investigated.The result showed that the optimal fermentation conditions were as followed:medium volume 70 mL per 250mL flask, inoculum 5%, rotation speed 150r · min-1 , temperature 32℃ and fermentation time 5d.Under these conditions,the yield of 0.5cm~0.8cm BC pellets reached 89.5%,and dry weight was 6.56g· L-1.%以解淀粉芽孢杆菌ZF-7(Bacillus amyloliquefaciens ZF-7)为菌源,对其动态发酵生产细菌纤维素(Bacterial cellulose,BC)的发酵工艺条件进行优化. 利用单因素试验,以粒径为0.5cm~0.8cm的BC颗粒产量及其占总纤维素比率为考察指标,考察摇床转速、装液量、温度、接种量及培养时间对其BC颗粒形成的影响,探索最佳动态发酵工艺. 结果表明:最优培养条件为装液量70mL/250mL三角瓶,接种量5%,150r· min -1 , 32℃振荡培养5d,在此条件下,可获得89.5%的φ0.5cm~0.8cm颗粒状BC,干重为6.56g· L -1.

  20. Formation of nanowires via single particle-triggered linear polymerization of solid-state aromatic molecules.

    Science.gov (United States)

    Horio, Akifumi; Sakurai, Tsuneaki; Lakshmi, G B V S; Kumar Avasthi, Devesh; Sugimoto, Masaki; Yamaki, Tetsuya; Seki, Shu

    2016-08-11

    Nanowires occupy a prestigious place in nanoelectronics, nanomechanics, and biomimetics. Although there are notable methods to grow nanowires via self-assembly, there is a key drawback in the need to find out the specific conditions appropriate for each system. In this sense, universal techniques to fabricate such nanowires from various organic materials have been sought for the continued progress of the related research field. Here we report one of the promising and facile methodologies to quantitatively produce nanowires with controlled geometrical parameters. In this method, referred to as "Single Particle-Triggered Linear Polymerization (STLiP)", organic thin films on a supporting substrate were irradiated with high-energy charged particles, accelerated by particle accelerators. Each particle penetrates from the top of the films to the substrate while gradually releasing kinetic energy along its trajectory (ion track), generating reactive intermediates such as radical species that eventually induce propagation reactions. The resulting polymerized products were integrated into nanowires with uniform diameter and length that can be isolated via development with appropriate organic solvents. Considering the widely applicable nature of STLiP to organic materials, the present technique opens a new door for access to a number of functional nanowires and their assembly. PMID:27355341

  1. Effect of diborane on the microstructure of boron-doped silicon nanowires

    Science.gov (United States)

    Pan, Ling; Lew, Kok-Keong; Redwing, Joan M.; Dickey, Elizabeth C.

    2005-04-01

    Boron-doped silicon (Si) nanowires, with nominal diameters of 80 nm, were grown via the vapor-liquid-solid (VLS) mechanism using gold (Au) as a catalyst and silane (SiH 4) and diborane (B 2H 6) as precursors. The microstructure of the nanowires was studied by scanning electron microscopy, transmission electron microscopy and electron energy-loss spectroscopy. At lower B 2H 6 partial pressure and thus lower doping levels (⩽1×10 18 cm -3), most of the boron-doped Si nanowires exhibited high crystallinity. At higher B 2H 6 partial pressure (˜2×10 19 cm -3 doping level), the majority of the wires exhibited a core-shell structure with an amorphous Si shell (20-30 nm thick) surrounding a crystalline Si core. Au nanoparticles on the outer surface of the nanowires were also observed in structures grown with high B/Si gas ratios. The structural changes are believed to result from an increase in the rate of Si thin-film deposition on the outer surface of the nanowire at high B 2H 6 partial pressure, which produces the amorphous coating and also causes an instability at the liquid/solid interface resulting in a loss of Au during nanowire growth.

  2. Tailoring light-matter coupling in semiconductor and hybrid-plasmonic nanowires

    Science.gov (United States)

    Piccione, Brian; Aspetti, Carlos O.; Cho, Chang-Hee; Agarwal, Ritesh

    2014-08-01

    Understanding interactions between light and matter is central to many fields, providing invaluable insights into the nature of matter. In its own right, a greater understanding of light-matter coupling has allowed for the creation of tailored applications, resulting in a variety of devices such as lasers, switches, sensors, modulators, and detectors. Reduction of optical mode volume is crucial to enhancing light-matter coupling strength, and among solid-state systems, self-assembled semiconductor and hybrid-plasmonic nanowires are amenable to creation of highly-confined optical modes. Following development of unique spectroscopic techniques designed for the nanowire morphology, carefully engineered semiconductor nanowire cavities have recently been tailored to enhance light-matter coupling strength in a manner previously seen in optical microcavities. Much smaller mode volumes in tailored hybrid-plasmonic nanowires have recently allowed for similar breakthroughs, resulting in sub-picosecond excited-state lifetimes and exceptionally high radiative rate enhancement. Here, we review literature on light-matter interactions in semiconductor and hybrid-plasmonic monolithic nanowire optical cavities to highlight recent progress made in tailoring light-matter coupling strengths. Beginning with a discussion of relevant concepts from optical physics, we will discuss how our knowledge of light-matter coupling has evolved with our ability to produce ever-shrinking optical mode volumes, shifting focus from bulk materials to optical microcavities, before moving on to recent results obtained from semiconducting nanowires.

  3. Tailoring light–matter coupling in semiconductor and hybrid-plasmonic nanowires

    International Nuclear Information System (INIS)

    Understanding interactions between light and matter is central to many fields, providing invaluable insights into the nature of matter. In its own right, a greater understanding of light–matter coupling has allowed for the creation of tailored applications, resulting in a variety of devices such as lasers, switches, sensors, modulators, and detectors. Reduction of optical mode volume is crucial to enhancing light–matter coupling strength, and among solid-state systems, self-assembled semiconductor and hybrid-plasmonic nanowires are amenable to creation of highly-confined optical modes. Following development of unique spectroscopic techniques designed for the nanowire morphology, carefully engineered semiconductor nanowire cavities have recently been tailored to enhance light–matter coupling strength in a manner previously seen in optical microcavities. Much smaller mode volumes in tailored hybrid-plasmonic nanowires have recently allowed for similar breakthroughs, resulting in sub-picosecond excited-state lifetimes and exceptionally high radiative rate enhancement. Here, we review literature on light–matter interactions in semiconductor and hybrid-plasmonic monolithic nanowire optical cavities to highlight recent progress made in tailoring light–matter coupling strengths. Beginning with a discussion of relevant concepts from optical physics, we will discuss how our knowledge of light–matter coupling has evolved with our ability to produce ever-shrinking optical mode volumes, shifting focus from bulk materials to optical microcavities, before moving on to recent results obtained from semiconducting nanowires. (review article)

  4. Bacterial Adhesion & Blocking Bacterial Adhesion

    DEFF Research Database (Denmark)

    Vejborg, Rebecca Munk

    2008-01-01

    parameters, which influence the transition from a planktonic lifestyle to a sessile lifestyle, have been studied. Protein conditioning film formation was found to influence bacterial adhesion and subsequent biofilm formation considerable, and an aqueous extract of fish muscle tissue was shown to...... tract to the microbial flocs in waste water treatment facilities. Microbial biofilms may however also cause a wide range of industrial and medical problems, and have been implicated in a wide range of persistent infectious diseases, including implantassociated microbial infections. Bacterial adhesion is...... the first committing step in biofilm formation, and has therefore been intensely scrutinized. Much however, still remains elusive. Bacterial adhesion is a highly complex process, which is influenced by a variety of factors. In this thesis, a range of physico-chemical, molecular and environmental...

  5. Bacterial Ecology

    DEFF Research Database (Denmark)

    Fenchel, Tom

    2011-01-01

    Bacterial ecology is concerned with the interactions between bacteria and their biological and nonbiological environments and with the role of bacteria in biogeochemical element cycling. Many fundamental properties of bacteria are consequences of their small size. Thus, they can efficiently exploit...

  6. Optical properties of semiconducting nanowires

    NARCIS (Netherlands)

    Vugt, L.K. van

    2007-01-01

    Semiconductor nanowires of high purity and crystallinity hold promise as building blocks for opto-electronical devices at the nanoscale.. They are commonly grown via a Vapor-Liquid-Solid (VLS) mechanism in which metal (nano) droplets collect the semiconductor precursors to form a solution which, whe

  7. Surface physics of semiconducting nanowires

    Science.gov (United States)

    Amato, Michele; Rurali, Riccardo

    2016-02-01

    Semiconducting nanowires (NWs) are firm candidates for novel nanoelectronic devices and a fruitful playground for fundamental physics. Ultra-thin nanowires, with diameters below 10 nm, present exotic quantum effects due to the confinement of the wave functions, e.g. widening of the electronic band-gap, deepening of the dopant states. However, although several reports of sub-10 nm wires exist to date, the most common NWs have diameters that range from 20 to 200 nm, where these quantum effects are absent or play a very minor role. Yet, the research activity on this field is very intense and these materials still promise to provide an important paradigm shift for the design of emerging electronic devices and different kinds of applications. A legitimate question is then: what makes a nanowire different from bulk systems? The answer is certainly the large surface-to-volume ratio. In this article we discuss the most salient features of surface physics and chemistry in group-IV semiconducting nanowires, focusing mostly on Si NWs. First we review the state-of-the-art of NW growth to achieve a smooth and controlled surface morphology. Next we discuss the importance of a proper surface passivation and its role on the NW electronic properties. Finally, stressing the importance of a large surface-to-volume ratio and emphasizing the fact that in a NW the surface is where most of the action takes place, we discuss molecular sensing and molecular doping.

  8. Nanowire-based gas sensors

    NARCIS (Netherlands)

    Chen, X.; Wong, C.K.Y.; Yuan, C.A.; Zhang, G.

    2013-01-01

    Gas sensors fabricated with nanowires as the detecting elements are powerful due to their many improved characteristics such as high surface-to-volume ratios, ultrasensitivity, higher selectivity, low power consumption, and fast response. This paper gives an overview on the recent process of the dev

  9. Diagnosis of bacterial vaginosis

    Directory of Open Access Journals (Sweden)

    Đukić Slobodanka

    2013-01-01

    Full Text Available Bacterial vaginosis is a common, complex clinical syndrome characterized by alterations in the normal vaginal flora. When symptomatic, it is associated with a malodorous vaginal discharge and on occasion vaginal burning or itching. Under normal conditions, lactobacilli constitute 95% of the bacteria in the vagina. Bacterial vaginosis is associated with severe reduction or absence of the normal H2O2­producing lactobacilli and overgrowth of anaerobic bacteria and Gardnerella vaginalis, Atopobium vaginae, Mycoplasma hominis and Mobiluncus species. Most types of infectious disease are diagnosed by culture, by isolating an antigen or RNA/DNA from the microbe, or by serodiagnosis to determine the presence of antibodies to the microbe. Therefore, demonstration of the presence of an infectious agent is often a necessary criterion for the diagnosis of the disease. This is not the case for bacterial vaginosis, since the ultimate cause of the disease is not yet known. There are a variety of methods for the diagnosis of bacterial vaginosis but no method can at present be regarded as the best. Diagnosing bacterial vaginosis has long been based on the clinical criteria of Amsel, whereby three of four defined criteria must be satisfied. Nugent’s scoring system has been further developed and includes validation of the categories of observable bacteria structures. Up­to­date molecular tests are introduced, and better understanding of vaginal microbiome, a clear definition for bacterial vaginosis, and short­term and long­term fluctuations in vaginal microflora will help to better define molecular tests within the broader clinical context.

  10. TOPICAL REVIEW: DNA nanowire fabrication

    Science.gov (United States)

    Gu, Qun; Cheng, Chuanding; Gonela, Ravikanth; Suryanarayanan, Shivashankar; Anabathula, Sathish; Dai, Kun; Haynie, Donald T.

    2006-01-01

    Deoxyribonucleic acid (DNA) has been a key building block in nanotechnology since the earliest work on what is now called DNA-templated self-assembly (Alivisatos et al 1996 Nature 382 609; Mirkin et al 1996 Nature 382 607; Braun et al 1998 Nature 391 775). A range of different nanoparticles and nanoclusters have been assembled on single DNA molecules for a variety of purposes (Braun et al 1998 Nature 391 775; Richter et al 2001 Appl. Phys. Lett. 78 536; Park et al 2002 Science 295 1503; Mirkin 2000 Inorg. Chem. 39 2258; Keren et al 2003 Science 302 1380). Electrically conductive silver (Braun et al 1998 Nature 391 775) and palladium (Richter et al 2001 Appl. Phys. Lett. 78 536) nanowires, for example, have been fabricated by DNA templating for the development of interconnection of nanoelectric elements, and field effect transistors have been built by assembly of a single carbon nanotube and DNA-templated nanowires (Keren et al 2003 Science 302 1380). DNA is well suited for nanowire assembly because of its size, well organized structure, and exquisite molecular-recognition-ability-specific base pairing. This property has been used to detect nucleic acids (Park et al 2002 Science 295 1503) and anthrax (Mirkin 2000 Inorg. Chem. 39 2258) with high sensitivity and specificity. Molecular recognition can also be used to localize nanowires in electronics. Various methods, for example molecular combing, electrophoretic stretching, and hydrodynamic stretching, have been developed to orient DNA molecules on a solid support. This review focuses on methods used to manipulate and metallize DNA in nanowire fabrication. A novel approach based on a single-stranded DNA template and molecular recognition is also discussed.

  11. Structure and magnetic properties of electrodeposited cobalt nanowires

    Science.gov (United States)

    Bantu, A. Kazadi Mukenga; Rivas, J.; Zaragoza, G.; López-Quintela, M. A.; Blanco, M. C.

    2001-03-01

    This work focuses on the structural and magnetic characterization of arrays of cobalt nanowires, with diameters in the range 100-400 nm and lengths of L⩽6 μm, produced by electrodeposition in polycarbonate membrane pores. Diffraction patterns of Co nanowires indicate that Co is stabilized in the hcp structure with a preferential (0001) texture oriented close to the perpendicular direction of the wires axes. Magnetic measurements at room temperature reveal that magnetization undergoes a change in the easy axis as the length of the wires increases. Clearly, the easy axis of the shortest wires is oriented along the axis of the wire. In the case of the longest wires, a crossover of the easy axis is observed, from the perpendicular to the parallel direction to the wire for the shortest. This magnetic behavior is explained through a simple magnetostatic model, which takes into account the dipolar interactions among wires, the demagnetizing field, and the magnetocrystalline anisotropy of Co.

  12. Polysilicon Nanowires for chemical sensing applications

    OpenAIRE

    Jacques, Emmanuel; Ni, Liang; Salaun, Anne-Claire; Rogel, Régis; Pichon, Laurent

    2012-01-01

    Polycrystalline silicon nanowires are synthesized using a classical fabrication method commonly used in microelectronic industry: the sidewall spacer formation technique. Assets of this technological process rest on low cost lithographic tools use, classical silicon planar technology compatibility and the possibility to get by direct patterning numerous parallel nanowires with precise location on the substrate. Grounded and suspended polycrystalline silicon nanowires with a curvature radius a...

  13. Indium Antimonide Nanowires: Synthesis, Characterization, and Applications

    OpenAIRE

    Penchev, Miroslav Valentinov

    2012-01-01

    Indium Antimonide (InSb) nanowires with a diameter ranging from 30 nm to 200 nm, were synthesized by electrochemical disposition in anodized alumina and polycarbonate porous membranes. In addition, epitaxial single crystalline InSb nanowires with diameters ranging from 5 nm to 100 nm, were synthesized by chemical vapor deposition (CVD) using Au nanoparticles as catalyst. Structural and material characterization of InSb nanowires was carried out by scanning electron microscopy (SEM), energy di...

  14. Comparison of quantitative and qualitative antibody-producing cell responses to lipopolysaccharide in cell walls of the bacterial form and in membranes of the protoplast L-form of Proteus mirabilis.

    OpenAIRE

    Karch, H; Nixdorff, K

    1980-01-01

    Membranes of the stable protoplast L-form of Proteus mirabilis strain VI were highly immunogenic carriers of lipopolysaccharide when compared with the immune responses to lipopolysaccharide contained in cell walls of the bacterial form of this organism.

  15. [Bacterial vaginosis].

    Science.gov (United States)

    Romero Herrero, Daniel; Andreu Domingo, Antonia

    2016-07-01

    Bacterial vaginosis (BV) is the main cause of vaginal dysbacteriosis in the women during the reproductive age. It is an entity in which many studies have focused for years and which is still open for discussion topics. This is due to the diversity of microorganisms that cause it and therefore, its difficult treatment. Bacterial vaginosis is probably the result of vaginal colonization by complex bacterial communities, many of them non-cultivable and with interdependent metabolism where anaerobic populations most likely play an important role in its pathogenesis. The main symptoms are an increase of vaginal discharge and the unpleasant smell of it. It can lead to serious consequences for women, such as an increased risk of contracting sexually transmitted infections including human immunodeficiency virus and upper genital tract and pregnancy complications. Gram stain is the gold standard for microbiological diagnosis of BV, but can also be diagnosed using the Amsel clinical criteria. It should not be considered a sexually transmitted disease but it is highly related to sex. Recurrence is the main problem of medical treatment. Apart from BV, there are other dysbacteriosis less characterized like aerobic vaginitis of which further studies are coming slowly but are achieving more attention and consensus among specialists. PMID:27474242

  16. Enhanced ionized impurity scattering in nanowires

    Science.gov (United States)

    Oh, Jung Hyun; Lee, Seok-Hee; Shin, Mincheol

    2013-06-01

    The electronic resistivity in silicon nanowires is investigated by taking into account scattering as well as the donor deactivation from the dielectric mismatch. The effects of poorly screened dopant atoms from the dielectric mismatch and variable carrier density in nanowires are found to play a crucial role in determining the nanowire resistivity. Using Green's function method within the self-consistent Born approximation, it is shown that donor deactivation and ionized impurity scattering combined with the charged interface traps successfully to explain the increase in the resistivity of Si nanowires while reducing the radius, measured by Björk et al. [Nature Nanotech. 4, 103 (2009)].

  17. Preparation and characterization of haematite nanowire arrays

    CERN Document Server

    Xue, D S; Liu, Q F; Zhang, L Y

    2003-01-01

    Arrays of alpha-Fe sub 2 O sub 3 nanowires embedded in anodic alumina membranes were obtained after heat-treating beta-FeOOH nanowire arrays fabricated by electrochemical deposition. Haematite polycrystalline nanowires with maximum length of about 7 mu m and average diameter of about 120 nm were characterized by means of x-ray diffraction and transmission electron microscopy. The Morin temperature below 80 K and Neel temperature of about 350 K for the alpha-Fe sub 2 O sub 3 nanowire arrays, far lower than those of bulk material, were measured by Moessbauer spectroscopy and using a Magnetic Property Measurement System.

  18. Surfactant-Templated Mesoporous Metal Oxide Nanowires

    Directory of Open Access Journals (Sweden)

    Hongmei Luo

    2010-01-01

    Full Text Available We demonstrate two approaches to prepare mesoporous metal oxide nanowires by surfactant assembly and nanoconfinement via sol-gel or electrochemical deposition. For example, mesoporous Ta2O5 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.

  19. Electrochemical Preparation of WO_3 Nanowire Arrays

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    1 Results Ordered WO3 nanowires arrays have been fabricated by electrochemical deposition with anodic aluminum oxide (AAO) templates and annealing the W nanowire arrays in air at 400 ℃. The morphology and the chemical composition of WO3 nanowires arrays were characterized by Scanning Electron Microscopy (SEM),Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), and X-ray diffraction (XRD). The results show that the diameters of the WO3 nanowires are about 90 nm, which is in go...

  20. Constricted nanowire with stabilized magnetic domain wall

    Science.gov (United States)

    Sbiaa, R.; Al Bahri, M.

    2016-08-01

    Domain wall (DW)-based magnetic memory offers the possibility for increasing the storage capacity. However, stability of DW remains the major drawback of this scheme. In this letter, we propose a stepped nanowire for pinning DW in a desirable position. From micromagnetic simulation, the proposed design applied to in-plane magnetic anisotropy materials shows that by adjusting the nanowire step size and its width it is possible to stabilize DW for a desirable current density range. In contrast, only a movement of DW could be seen for conventional nanowire. An extension to a multi-stepped nanowire could be used for multi-bit per cell magnetic memory.

  1. 产细菌纤维素菌株中间葡糖醋杆菌的分离与发酵条件优化%Isolation and Culture Optimization of Bacterial Cellulose Producing Strain Gluconacetobacter intermedius

    Institute of Scientific and Technical Information of China (English)

    苏俊霞; 陆震鸣; 王宗敏; 史劲松; 陆茂林; 许正宏

    2015-01-01

    Five bacterial cellulose (BC) producing strains were isolated from solid -state fermentation cultures of traditional Chinese vinegar,and identified as Gluconacetobacter intermedius based on their physiological and biochemical characteristics as well as 16S rDNA sequence analysis. Strain 1-17 could produce more BC then the others. Furthermore,surface features and chemical structure of BC were analyzed by scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy,respectively. Effects of temperature,time,carbon sources and initial pH on BC production were tested. The optimal temperature for strain 1-17 was 35 ℃, and the fermentation time was 7 d. Glucose and glycerol were the optimal carbon sources,and the optimal initial pH was 6.0. Both lactate and calcium could promote the synthesis of BC. The yield of BC was improved from (3.90±0.08) g/L to (7.90±0.19) g/L under the optimal conditions.%从中国传统固态发酵食醋醋醅中分离出5株产细菌纤维素(BC)的菌株,经生理生化特征及16S rDNA序列分析,它们均属于中间葡糖醋杆菌(Gluconacetobacter intermedius),其中编号为1-17的菌株初始产量较高。应用扫描电镜技术(SEM)和傅里叶红外光谱技术(FT-IR)分析了BC结构特征。采用单因素研究了温度、培养时间、碳源、初始pH对BC合成的影响。确定菌株1-17最适温度为35℃,发酵时间为7 d,甘油和葡萄糖为最适碳源,最适初始pH为6.0,乳酸根离子和钙离子能够促进BC的合成。通过培养条件优化使得细菌纤维素产量从初始的(3.90±0.08) g/L增加到(7.90±0.19) g/L。

  2. Laser induced augmentation of silver nanospheres to nanowires in ethanol fostered by Poly Vinyl Pyrrolidone

    Energy Technology Data Exchange (ETDEWEB)

    Sebastian, Suneetha, E-mail: sunikutty@gmail.com; Linslal, C.L.; Vallabhan, C.P.G.; Nampoori, V.P.N.; Radhakrishnan, P.; Kailasnath, M.

    2014-11-30

    Highlights: • Silver nanospheres are synthesised in ethanol containing Poly Vinyl Pyrrolidone which acts as a polymeric capping agent to nanoparticles thus improving its stability. • Laser irradiation onto the colloidal solution of silver nanoparticles produced well defined nanowires through ripening mechanism promoted by Poly Vinyl Pyrrolidone. • Nanowires so formed are having an average length of 8.7 μm and width of 160 nm. - Abstract: Stable uniform silver nanospheres having an average diameter of 45 nm are synthesised in ethanol containing Poly Vinyl Pyrrolidone using Laser Ablation in Liquid technique. Further irradiation of the nanocolloidal solution by focussed laser beam produced stable well defined silver nanowires through ripening mechanism fostered by the presence of Poly Vinyl Pyrrolidone. Confirmation of the mechanism is obtained from Transmission Electron Microscopic images of the nanocolloidal solution irradiated for different time durations.

  3. Resistance of Single Ag Nanowire Junctions and Their Role in the Conductivity of Nanowire Networks.

    Science.gov (United States)

    Bellew, Allen T; Manning, Hugh G; Gomes da Rocha, Claudia; Ferreira, Mauro S; Boland, John J

    2015-11-24

    Networks of silver nanowires appear set to replace expensive indium tin oxide as the transparent conducting electrode material in next generation devices. The success of this approach depends on optimizing the material conductivity, which until now has largely focused on minimizing the junction resistance between wires. However, there have been no detailed reports on what the junction resistance is, nor is there a known benchmark for the minimum attainable sheet resistance of an optimized network. In this paper, we present junction resistance measurements of individual silver nanowire junctions, producing for the first time a distribution of junction resistance values and conclusively demonstrating that the junction contribution to the overall resistance can be reduced beyond that of the wires through standard processing techniques. We find that this distribution shows the presence of a small percentage (6%) of high-resistance junctions, and we show how these may impact the performance of network-based materials. Finally, through combining experiment with a rigorous model, we demonstrate the important role played by the network skeleton and the specific connectivity of the network in determining network performance. PMID:26448205

  4. Indium Tin Oxide@Carbon Core–Shell Nanowire and Jagged Indium Tin Oxide Nanowire

    Directory of Open Access Journals (Sweden)

    Wang Yong

    2010-01-01

    Full Text Available Abstract This paper reports two new indium tin oxide (ITO-based nanostructures, namely ITO@carbon core–shell nanowire and jagged ITO nanowire. The ITO@carbon core–shell nanowires (~50 nm in diameter, 1–5 μm in length, were prepared by a chemical vapor deposition process from commercial ITO nanoparticles. A carbon overlayer (~5–10 in thickness was observed around ITO nanowire core, which was in situ formed by the catalytic decomposition of acetylene gas. This carbon overlayer could be easily removed after calcination in air at an elevated temperature of 700°C, thus forming jagged ITO nanowires (~40–45 nm in diameter. The growth mechanisms of ITO@carbon core–shell nanowire and jagged ITO nanowire were also suggested.

  5. Controlled growth of single nanowires within a supported alumina template

    Energy Technology Data Exchange (ETDEWEB)

    Vlad, A [Unite de Dispositifs Integres et Circuits Electroniques, Universite Catholique de Louvain (UCL), Place de Levant, 3, B-1348 Louvain-la-Neuve (Belgium); Matefi-Tempfli, M [Unite de Physico-Chimie et de Physique des Materiaux, UCL, Place Croix du Sud, 1, B-1348 Louvain-la-Neuve (Belgium); Faniel, S [Unite de Dispositifs Integres et Circuits Electroniques, Universite Catholique de Louvain (UCL), Place de Levant, 3, B-1348 Louvain-la-Neuve (Belgium); Bayot, V [Unite de Dispositifs Integres et Circuits Electroniques, Universite Catholique de Louvain (UCL), Place de Levant, 3, B-1348 Louvain-la-Neuve (Belgium); Melinte, S [Unite de Dispositifs Integres et Circuits Electroniques, Universite Catholique de Louvain (UCL), Place de Levant, 3, B-1348 Louvain-la-Neuve (Belgium); Piraux, L [Unite de Physico-Chimie et de Physique des Materiaux, UCL, Place Croix du Sud, 1, B-1348 Louvain-la-Neuve (Belgium); Matefi-Tempfli, S [Unite de Physico-Chimie et de Physique des Materiaux, UCL, Place Croix du Sud, 1, B-1348 Louvain-la-Neuve (Belgium)

    2006-10-14

    A simple technique for fabricating single nanowires with well-defined position is presented. The process implies the use of a silicon nitride mask for selective electrochemical growth of the nanowires in a porous alumina template. We show that this method allows the realization of complex nanowire patterns as well as arrays of single nanowires with a precise position and spacing.

  6. Controlled growth of single nanowires within a supported alumina template

    Science.gov (United States)

    Vlad, A.; Mátéfi-Tempfli, M.; Faniel, S.; Bayot, V.; Melinte, S.; Piraux, L.; Mátéfi-Tempfli, S.

    2006-10-01

    A simple technique for fabricating single nanowires with well-defined position is presented. The process implies the use of a silicon nitride mask for selective electrochemical growth of the nanowires in a porous alumina template. We show that this method allows the realization of complex nanowire patterns as well as arrays of single nanowires with a precise position and spacing.

  7. Growth mechanism and quantum confinement effect of silicon nanowires

    Institute of Scientific and Technical Information of China (English)

    冯孙齐; 俞大鹏; 张洪洲; 白志刚; 丁彧; 杭青岭; 邹英华; 王晶晶

    1999-01-01

    The methods for synthesizing one-dimensional Si nanowires with controlled diameter are introduced. The mechanism for the growth of Si nanowires and the growth model for different morphologies of Si nanowires are described, and the quantum confinement effect of the Si nanowires is presented.

  8. Transport Measurements on Superconducting Nanowires

    Science.gov (United States)

    Kurtz, J. S.; Tian, M.; Garcia, R.; Mallouk, T. E.; Mayer, T. S.; Liu, Y.; Chan, M. H. W.

    2003-03-01

    High quality, single-crystal nanowires of various elemental metals and superconductors have been fabricated by electro-deposition into porous alumina and polycarbonate membranes. We report here recent magneto-transport measurements at low temperatures on such superconducting Sn nanowires with diameters smaller than the bulk coherence length and penetration depth. These wires allow an investigation of one-dimensional superconductivity in the regime of very low disorder. Transport properties were measured for wires of various diameters in a dilution refrigerator under magnetic fields up to 9 Tesla. Superconducting transitions were observed, and deviations from bulk, 3D behavior such as low-temperature resistive tails and high critical fields will be presented and discussed. This work is supported by NSF MRSEC Grants DMR 0080019 and DMR 0213623.

  9. Nanowire-based Quantum Photonics

    OpenAIRE

    Bulgarini, G.

    2014-01-01

    In this thesis work, I studied individual quantum dots embedded in one-dimensional nanostructures called nanowires. Amongst the effects given by the nanometric dimensions, quantum dots enable the generation of single light particles: photons. Single photon emitters and detectors are central building blocks of future communication technologies. As the miniaturization in electronics is driving towards the quantum limit, we envision future telecommunication as based on single photons. Single pho...

  10. Nanowire sensors and arrays for chemical/biomolecule detection

    Science.gov (United States)

    Yun, Minhee; Lee, Choonsup; Vasquez, Richard P.; Ramanathan, K.; Bangar, M. A.; Chen, W.; Mulchandan, A.; Myung, N. V.

    2005-01-01

    We report electrochemical growth of single nanowire based sensors using e-beam patterned electrolyte channels, potentially enabling the controlled fabrication of individually addressable high density arrays. The electrodeposition technique results in nanowires with controlled dimensions, positions, alignments, and chemical compositions. Using this technique, we have fabricated single palladium nanowires with diameters ranging between 75 nm and 300 nm and conducting polymer nanowires (polypyrrole and polyaniline) with diameters between 100 nm and 200 nm. Using these single nanowires, we have successfully demonstrated gas sensing with Pd nanowires and pH sensing with polypirrole nanowires.

  11. Enhanced photovoltaic performance of an inclined nanowire array solar cell.

    Science.gov (United States)

    Wu, Yao; Yan, Xin; Zhang, Xia; Ren, Xiaomin

    2015-11-30

    An innovative solar cell based on inclined p-i-n nanowire array is designed and analyzed. The results show that the inclined geometry can sufficiently increase the conversion efficiency of solar cells by enhancing the absorption of light in the active region. By tuning the nanowire array density, nanowire diameter, nanowire length, as well as the proportion of intrinsic region of the inclined nanowire solar cell, a remarkable efficiency in excess of 16% can be obtained in GaAs. Similar results have been obtained in InP and Si nanowire solar cells, demonstrating the universality of the performance enhancement of inclined nanowire arrays. PMID:26698807

  12. Transparent conducting silver nanowire networks

    CERN Document Server

    van de Groep, Jorik; Polman, Albert; 10.1021/nl301045a

    2013-01-01

    We present a transparent conducting electrode composed of a periodic two-dimensional network of silver nanowires. Networks of Ag nanowires are made with wire diameters of 45-110 nm and pitch of 500, 700 and 1000 nm. Anomalous optical transmission is observed, with an averaged transmission up to 91% for the best transmitting network and sheet resistances as low as 6.5 {\\Omega}/sq for the best conducting network. Our most dilute networks show lower sheet resistance and higher optical transmittance than an 80 nm thick layer of ITO sputtered on glass. By comparing measurements and simulations we identify four distinct physical phenomena that govern the transmission of light through the networks: all related to the excitation of localized surface plasmons and surface plasmon polaritons on the wires. The insights given in this paper provide the key guidelines for designing high-transmittance and low-resistance nanowire electrodes for optoelectronic devices, including thin-film solar cells. For these latter, we disc...

  13. Compact Nanowire Sensors Probe Microdroplets.

    Science.gov (United States)

    Schütt, Julian; Ibarlucea, Bergoi; Illing, Rico; Zörgiebel, Felix; Pregl, Sebastian; Nozaki, Daijiro; Weber, Walter M; Mikolajick, Thomas; Baraban, Larysa; Cuniberti, Gianaurelio

    2016-08-10

    The conjunction of miniature nanosensors and droplet-based microfluidic systems conceptually opens a new route toward sensitive, optics-less analysis of biochemical processes with high throughput, where a single device can be employed for probing of thousands of independent reactors. Here we combine droplet microfluidics with the compact silicon nanowire based field effect transistor (SiNW FET) for in-flow electrical detection of aqueous droplets one by one. We chemically probe the content of numerous (∼10(4)) droplets as independent events and resolve the pH values and ionic strengths of the encapsulated solution, resulting in a change of the source-drain current ISD through the nanowires. Further, we discuss the specificities of emulsion sensing using ion sensitive FETs and study the effect of droplet sizes with respect to the sensor area, as well as its role on the ability to sense the interior of the aqueous reservoir. Finally, we demonstrate the capability of the novel droplets based nanowire platform for bioassay applications and carry out a glucose oxidase (GOx) enzymatic test for glucose detection, providing also the reference readout with an integrated parallel optical detector. PMID:27417510

  14. Formation of dendritic metallic nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Ranjan, Nitesh; Mertig, Michael [Institute for Materials Science, Max Bergmann Center of Biomaterials, Dresden University of Technology, D-01062 Dresden (Germany); Vinzelberg, Hartmut [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany)

    2009-07-01

    Recently, we reported an electrical-field-controlled growth process for the directed bottom-up assembly of one-dimensional palladium nanowires between micro-fabricated electrodes. The wires, grown from an aqueous palladium salt solution by dielectrophoresis, had a thickness of only 5-10 nm and a length of up to several micrometers. The growth process was found to depend largely on the deposition conditions like the strength and the frequency of the applied AC field and the concentration of the metal salt solution. Here, we report the formation of thin, but straight and dendritic metallic nanowires, obtained in the low-frequency regime. The morphology of the wires was characterized by scanning force microscopy (SFM), scanning electron microscopy and transmission electron microscopy. SFM investigations revealed that the palladium nanowires grown over the glass and silicon substrates have a typical thickness of about 25 nm. Room temperature I-V measurements show them to be Ohmic in nature with a resistance of about 80 kOhm. Low-temperature measurements show the phenomenon of zero bias anomaly. The investigated growth method is capable of controllable in-place formation of complex circuit patterns for future nanoelectronics.

  15. DNA hybridization on silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Shalini, E-mail: shalinsin@gmail.co [Electronic Materials Division, National Physical Laboratory (CSIR), Dr. K. S. Krishnan Marg, New Delhi-110012 (India); Faculty of Life Science, Aligarh Muslim University, Aligarh-202001 (India); Zack, Jyoti [Dr. B.R Ambedkar Center for Biomedical Research, University of Delhi, Delhi-110007 (India); Kumar, Dinesh; Srivastava, S.K.; Govind [Electronic Materials Division, National Physical Laboratory (CSIR), Dr. K. S. Krishnan Marg, New Delhi-110012 (India); Saluja, Daman [Dr. B.R Ambedkar Center for Biomedical Research, University of Delhi, Delhi-110007 (India); Khan, M.A. [Faculty of Life Science, Aligarh Muslim University, Aligarh-202001 (India); Singh, P.K. [Electronic Materials Division, National Physical Laboratory (CSIR), Dr. K. S. Krishnan Marg, New Delhi-110012 (India)

    2010-11-30

    Nanowire-based detection strategies provide promising new routes to bioanalysis and indeed are attractive to conventional systems because of their small size, high surface-to-volume ratios, electronic, and optical properties. A sequence-specific detection of single-stranded oligonucleotides using silicon nanowires (SiNWs) is demonstrated. The surface of the SiNWs is functionalized with densely packed organic monolayer via hydrosilylation for covalent attachment. Subsequently, deoxyribonucleic acid (DNA) is immobilized to recognize the complementary target DNA. The biomolecular recognition properties of the nanowires are tested via hybridization with {sup {gamma}P32} tagged complementary and non-complementary DNA oligonucleotides, showing good selectivity and reversibility. No significant non-specific binding to the incorrect sequences is observed. X-ray photoelectron spectroscopy, fluorescence imaging, and nanodrop techniques are used to characterize the modified SiNWs and covalent attachment with DNA. The results show that SiNWs are excellent substrates for the absorption, stabilization and detection of DNA sequences and could be used for DNA microarrays and micro fabricated SiNWs DNA sensors.

  16. Piezoelectric-nanowire-enabled power source for driving wireless microelectronics.

    Science.gov (United States)

    Xu, Sheng; Hansen, Benjamin J; Wang, Zhong Lin

    2010-01-01

    Harvesting energy from irregular/random mechanical actions in variable and uncontrollable environments is an effective approach for powering wireless mobile electronics to meet a wide range of applications in our daily life. Piezoelectric nanowires are robust and can be stimulated by tiny physical motions/disturbances over a range of frequencies. Here, we demonstrate the first chemical epitaxial growth of PbZr(x)Ti(1-x)O(3) (PZT) nanowire arrays at 230 °C and their application as high-output energy converters. The nanogenerators fabricated using a single array of PZT nanowires produce a peak output voltage of ~0.7 V, current density of 4 μA cm(-2) and an average power density of 2.8 mW cm(-3). The alternating current output of the nanogenerator is rectified, and the harvested energy is stored and later used to light up a commercial laser diode. This work demonstrates the feasibility of using nanogenerators for powering mobile and even personal microelectronics. PMID:20981021

  17. Investigation of functionalized silicon nanowires by self-assembled monolayer

    Science.gov (United States)

    Hemed, Nofar Mintz; Convertino, Annalisa; Shacham-Diamand, Yosi

    2016-03-01

    The functionalization using self assembled monolayer (SAM) of silicon nanowires (SiNW) fabricated by plasma enhanced chemical vapor deposition (PECVD) is reported here. The SAM is being utilized as the first building block in the functionalization process. The morphology of the SiNW comprises a polycrystalline core wrapped by an hydrogenated amorphous silicon (α-Si:H) shell. Since most of the available methods for SAM verification and characterization are suitable only for flat substrates; therefore, in addition to the SiNW α-Si:H on flat samples were produced in the same system as the SiNWs. First we confirmed the SAM's presence on the flat α-Si:H samples using the following methods: contact angle measurement to determine the change in surface energy; atomic force microscopy (AFM) to determine uniformity and molecular coverage. Spectroscopic ellipsometry and X-ray reflectivity (XRR) were performed to measure SAM layer thickness and density. X-ray photoelectron spectroscopy (XPS) was applied to study the chemical states of the surface. Next, SiNW/SAM were tested by electrochemical impedance spectroscopy (EIS), and the results were compared to α-Si:H/SAM. The SAM electrical coverage on SiNW and α-Si:H was found to be ∼37% and ∼65 ± 3%, respectively. A model, based on transmission line theory for the nanowires is presented to explain the disparity in results between the nanowires and flat surface of the same materials.

  18. Nanowire sensor, sensor array, and method for making the same

    Science.gov (United States)

    Yun, Minhee (Inventor); Myung, Nosang (Inventor); Vasquez, Richard (Inventor); Homer, Margie (Inventor); Ryan, Margaret (Inventor); Yen, Shiao-Pin (Inventor); Fleurial, Jean-Pierre (Inventor); Bugga, Ratnakumar (Inventor); Choi, Daniel (Inventor); Goddard, William (Inventor)

    2012-01-01

    The present invention relates to a nanowire sensor and method for forming the same. More specifically, the nanowire sensor comprises at least one nanowire formed on a substrate, with a sensor receptor disposed on a surface of the nanowire, thereby forming a receptor-coated nanowire. The nanowire sensor can be arranged as a sensor sub-unit comprising a plurality of homogeneously receptor-coated nanowires. A plurality of sensor subunits can be formed to collectively comprise a nanowire sensor array. Each sensor subunit in the nanowire sensor array can be formed to sense a different stimulus, allowing a user to sense a plurality of stimuli. Additionally, each sensor subunit can be formed to sense the same stimuli through different aspects of the stimulus. The sensor array is fabricated through a variety of techniques, such as by creating nanopores on a substrate and electrodepositing nanowires within the nanopores.

  19. Functionalization of magnetic nanowires by charged biopolymers

    DEFF Research Database (Denmark)

    Magnin, D.; Callegari, V.; Mátéfi-Tempfli, Stefan;

    2008-01-01

    an alumina template supported on a silicon wafer. Carboxymethylpullulan (CMP) and chitosan (CHI) multilayers were grown on brushes of Ni nanowires; subsequent grafting of an enzyme was performed by conjugating free amine side groups of chitosan with carboxylic groups of the enzyme. The nanowires are...

  20. High-Performance Single Nanowire Tunnel Diodes

    DEFF Research Database (Denmark)

    Wallentin, Jesper; Persson, Johan Mikael; Wagner, Jakob Birkedal;

    2010-01-01

    We demonstrate single nanowire tunnel diodes with room temperature peak current densities of up to 329 A/cm(2). Despite the large surface to volume ratio of the type-II InP-GaAs axial heterostructure nanowires, we measure peak to valley current ratios (PVCR) of up to 8.2 at room temperature and 2...

  1. Growth of ZnO nanowire arrays directly onto Si via substrate topographical adjustments using both wet chemical and dry etching methods

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Nathan A., E-mail: 523615@swansea.ac.uk [Centre for Nanohealth, Department of Physics, College of Science, University of Swansea, Singleton Park SA2 8PP United Kingdom (United Kingdom); Evans, Jon E.; Jones, Daniel R. [Multidisciplinary Nanotechnology Centre, College of Engineering, University of Swansea, Singleton Park, SA2 8PP United Kingdom (United Kingdom); Lord, Alex M. [Centre for Nanohealth, College of Engineering, University of Swansea, Singleton Park, SA2 8PP United Kingdom (United Kingdom); Wilks, S.P. [Centre for Nanohealth, Department of Physics, College of Science, University of Swansea, Singleton Park SA2 8PP United Kingdom (United Kingdom)

    2015-03-15

    Highlights: • Arrays of catalyst-free ZnO NWs have been grown by CVD without seed layers on Si. • Si surface topography was altered by substrate etching, resulting in NW growth. • XPS analysis shows growth is related to topography and not surface contamination. • Using e-beam lithography with etching, selective nanowire growth is demonstrated. • Electrical measurements on the arrays show improved conduction through the Si. - Abstract: Arrays of CVD catalyst-free ZnO nanowires have been successfully grown without the use of seed layers, using both wet chemical and dry plasma etching methods to alter surface topography. XPS analysis indicates that the NW growth cannot be attributed to a substrate surface chemistry and is therefore directly related to the substrate topography. These nanowires demonstrate structural and optical properties typical of CVD ZnO nanowires. Moreover, the NW arrays exhibit a degree of vertical alignment of less than 20° from the substrate normal. Electrical measurements suggest an improved conduction path through the substrate over seed layer grown nanowires. Furthermore, the etching technique was combined with e-beam lithography to produce high resolution selective area nanowire growth. The ability to pattern uniform nanowires using mature dry etch technology coupled with the increased charge transport through the substrate demonstrates the potential of this technique in the vertical integration of nanowire arrays.

  2. Study of the growth, and effects of filament to substrate distance on the structural and optical properties of Si/SiC core–shell nanowires synthesized by hot-wire chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Goh, Boon Tong, E-mail: boontong77@yahoo.com; Rahman, Saadah Abdul

    2014-10-15

    Silicon/silicon carbide (Si/SiC) core–shell nanowires grown on quartz substrates by hot-wire chemical vapor deposition were studied. Nickel was used as a catalyst to induce the growth of these core–shell nanowires followed by the vapor–solid–solid growth mechanism. The nanowires were grown by varying substrate-to-filament distance; d{sub s-f} from 1.9 to 3.1 cm with an interval of 0.4 cm. Lower d{sub s-f} produced a high density of straight core–shell nanowires. A highly crystalline single crystal Si core of the nanowires was produced at lower d{sub s-f} as well. Presence of Si and SiC nano-crystallites embedded within an amorphous matrix in the shell of the nanowires exhibited a high intensity of photoluminescence emission spectra from 600 to 1000 nm. The effects of the d{sub s-f} on the structural and optical properties of the nanowires are discussed. - Highlights: • Growth of Si/SiC core–shell nanowires on Ni nano-templetes. • Atomic hydrogen radicals induced the catalytic growth of the nanowires. • Low substrate to filament distance enhanced the catalytic effect. • Presence of Si nano-crystallites in the shell exhibited strong PL emission.

  3. Electroless Fabrication of Cobalt Alloys Nanowires within Alumina Template

    OpenAIRE

    Nazila Dadvand; Kipouros, Georges J.

    2007-01-01

    A new method of nanowire fabrication based on electroless deposition process is described. The method is novel compared to the current electroless procedure used in making nanowires as it involves growing nanowires from the bottom up. The length of the nanowires was controlled at will simply by adjusting the deposition time. The nanowires were fabricated within the nanopores of an alumina template. It was accomplished by coating one side of the template by a thin layer of palladium in order t...

  4. Deflections of Nanowires with Consideration of Surface Effects

    Institute of Scientific and Technical Information of China (English)

    LI He; YANG Zhou; ZHANG Yi-Min; WEN Bang-Chun

    2010-01-01

    @@ The elementary beam model is modified to include the surface effects and used to analyze the deflections of nanowires under different boundary conditions.The results show that compared to deflections of nanowires without consideration of surface effects,the surface effects can enlarge or reduce deflections of nanowires,and nanowire buckling occurs under certaJn conditions.This study might be helpful for design of nanowire-based nanoelectromechanical systems.

  5. Superconductive silicon nanowires using gallium beam lithography.

    Energy Technology Data Exchange (ETDEWEB)

    Henry, Michael David; Jarecki, Robert Leo,

    2014-01-01

    This work was an early career LDRD investigating the idea of using a focused ion beam (FIB) to implant Ga into silicon to create embedded nanowires and/or fully suspended nanowires. The embedded Ga nanowires demonstrated electrical resistivity of 5 m-cm, conductivity down to 4 K, and acts as an Ohmic silicon contact. The suspended nanowires achieved dimensions down to 20 nm x 30 nm x 10 m with large sensitivity to pressure. These structures then performed well as Pirani gauges. Sputtered niobium was also developed in this research for use as a superconductive coating on the nanowire. Oxidation characteristics of Nb were detailed and a technique to place the Nb under tensile stress resulted in the Nb resisting bulk atmospheric oxidation for up to years.

  6. Ion beam induced alignment of semiconductor nanowires

    International Nuclear Information System (INIS)

    Epitaxially grown GaAs nanowires were irradiated with different kinds of energetic ions. The growth substrates were GaAs, and the nanowires grow under an angle of 35 circle. A bending of the nanowires was observed under ion beam irradiation, where the direction and magnitude of the bending depends on the energy, the species, and fluence of the incident ions. By choosing suitable ion beam parameters the nanowires could be realigned towards the ion beam direction. In order to understand the underlying mechanisms, computer simulations of the ion irradiation were done using a special version of TRIM which accounts for the geometry of the nanowires. The simulated distributions indicate vacancy and interstitial formation within the implantation cascade as the key mechanism for bending.

  7. Thermal evaporation synthesis of zinc oxide nanowires

    Science.gov (United States)

    Xing, Y. J.; Xi, Z. H.; Zhang, X. D.; Song, J. H.; Wang, R. M.; Xu, J.; Xue, Z. Q.; Yu, D. P.

    2005-04-01

    High quality ZnO nanowires were synthesized at high temperature without using heterogenous catalysts. The nanowires had a uniform prismatic shape and were grown in a cacti-like morphology. Characterizations of the products by X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy showed that the ZnO nanowires were single crystalline and of high purity. An intensive exciton emission was observed around 3.25 eV from the ZnO nanowires at room temperature. The growth mechanism was discussed based on the experimental conditions and the ZnO crystal growth habits. This growth method can be used to prepare other metal oxide nanowires.

  8. Thermal evaporation synthesis of zinc oxide nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Y.J. [Peking University, Department of Electronics, Beijing (China); Peking University, School of Physics, Electron Microscopy Laboratory, and State Key Laboratory for Mesoscopic Physics, Beijing (China); Xi, Z.H.; Zhang, X.D.; Song, J.H.; Xue, Z.Q. [Peking University, Department of Electronics, Beijing (China); Wang, R.M.; Xu, J.; Yu, D.P. [Peking University, School of Physics, Electron Microscopy Laboratory, and State Key Laboratory for Mesoscopic Physics, Beijing (China)

    2005-04-01

    High quality ZnO nanowires were synthesized at high temperature without using heterogenous catalysts. The nanowires had a uniform prismatic shape and were grown in a cacti-like morphology. Characterizations of the products by X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy showed that the ZnO nanowires were single crystalline and of high purity. An intensive exciton emission was observed around 3.25 eV from the ZnO nanowires at room temperature. The growth mechanism was discussed based on the experimental conditions and the ZnO crystal growth habits. This growth method can be used to prepare other metal oxide nanowires. (orig.)

  9. Synthesis of silicon and germanium nanowires.

    Energy Technology Data Exchange (ETDEWEB)

    Clement, Teresa J. (Arizona State University); Hsu, Julia W. P.

    2007-11-01

    The vapor-liquid-solid growth process for synthesis of group-IV semiconducting nanowires using silane, germane, disilane and digermane precursor gases has been investigated. The nanowire growth process combines in situ gold seed formation by vapor deposition on atomically clean silicon (111) surfaces, in situ growth from the gaseous precursor(s), and real-time monitoring of nanowire growth as a function of temperature and pressure by a novel optical reflectometry technique. A significant dependence on precursor pressure and growth temperature for the synthesis of silicon and germanium nanowires is observed, depending on the stability of the specific precursor used. Also, the presence of a nucleation time for the onset of nanowire growth has been found using our new in situ optical reflectometry technique.

  10. Nanowires for thermal energy conversion and management

    Science.gov (United States)

    Chen, Renkun

    This dissertation presents the application of nanowires in two aspects of thermal energy conversion and management: (i) silicon (Si) nanowires as efficient and scalable thermoelectric materials due to the reduced thermal conductivity (k), and (ii) Si and copper (Cu) nanowire arrays for enhanced phase change heat transfer including boiling and evaporation and their applications in thermal management of microelectronics. In the first half of the thesis (chapter 2 and 3), we describe thermal and thermoelectric measurements of individual Si nanowires for studying phonon transport properties and their potential application in thermoelectrics. A theoretical model based on coherent phonon scattering was developed to explain the experiemental data, which suggests that phonon-boundary scattering is highly frequency dependent. For low frequency (long wavelength) phonons, the transport is nearly ballistic, whereas high frequency or short wavelength phonons scatter diffusively at nanowire boundary. The competition between the two phonon transmission regimes results in the unusual linear behavior of the thermal conductance of thin VLS Si nanowires at low temperature. Next, the thermal conductivity of EE Si nanowires, which have much rougher surface compared to VLS nanowires, was measured and found to be five-eight times lower than that of VLS counterparts with similar diameters. The substantial reduction in k is presumably due to the higher surface roughness, since both types of nanowires have single crystalline cores. In particular, for ˜ 50 nm EE Si nanowires etched from 0.1 O-cm B-doped p-Si (˜2 x 1017 cm-3 dopant concentration), the k is around 1.6 Wm-1K-1 and the kL is ˜1.2 Wm-1 K-1 at room temperature, approaching that of amorphous Si. The single nanowire measurements show the great promise of using Si nanowire arrays as high-performance, scalable thermoelectric materials. As the second focus of the thesis (chapter 4 and 5), nanowire arrays were used for enhanced phase

  11. Stress-driven growth of bismuth nanowires

    Science.gov (United States)

    Cheng, Yang-Tse; Weiner, Anita M.; Wong, Curtis A.; Balogh, Michael P.; Lukitsch, Michael J.

    2003-03-01

    We recently reported that compressive stresses in thin films can be exploited to grow nanowires (Ref.1). Nanowires of bismuth (Bi) with diameters ranging from 30 to 200 nm and lengths up to several millimeters were formed spontaneously at the rate of a few micrometers per second at room temperature on surfaces of freshly grown composite thin films consisting of Bi and chrome-nitride (CrN). The high compressive stress in the composite thin films was shown to be the driving force responsible for the nanowire formation. In this presentation, the effects of stress, composition, and temperature on the growth and structure of bismuth nanowires will be discussed. This method of growing nanowires can also be extended to other material systems. Ref. 1. Yang-Tse Cheng, Anita M. Weiner, Curtis A. Wong, Michael P. Balogh, and Michael J. Lukitsch, Applied Physics Letters 81, 3248 (2002).

  12. Bandgap engineering of GaN nanowires

    Science.gov (United States)

    Ming, Bang-Ming; Wang, Ru-Zhi; Yam, Chi-Yung; Xu, Li-Chun; Lau, Woon-Ming; Yan, Hui

    2016-05-01

    Bandgap engineering has been a powerful technique for manipulating the electronic and optical properties of semiconductors. In this work, a systematic investigation of the electronic properties of [0001] GaN nanowires was carried out using the density functional based tight-binding method (DFTB). We studied the effects of geometric structure and uniaxial strain on the electronic properties of GaN nanowires with diameters ranging from 0.8 to 10 nm. Our results show that the band gap of GaN nanowires depends linearly on both the surface to volume ratio (S/V) and tensile strain. The band gap of GaN nanowires increases linearly with S/V, while it decreases linearly with increasing tensile strain. These linear relationships provide an effect way in designing GaN nanowires for their applications in novel nano-devices.

  13. Polarization response of nanowires à la carte.

    Science.gov (United States)

    Casadei, Alberto; Llado, Esther Alarcon; Amaduzzi, Francesca; Russo-Averchi, Eleonora; Rüffer, Daniel; Heiss, Martin; Dal Negro, Luca; Fontcuberta i Morral, Anna

    2015-01-01

    Thanks to their special interaction with light, semiconductor nanowires have opened new avenues in photonics, quantum optics and solar energy harvesting. One of the major challenges for their full technological deployment has been their strong polarization dependence in light absorption and emission. In the past, metal nanostructures have been shown to have the ability to modify and enhance the light response of nanoscale objects. Here we demonstrate that a hybrid structure formed by GaAs nanowires with a highly dense array of bow-tie antennas is able to modify the polarization response of a nanowire. As a result, the increase in light absorption for transverse polarized light changes the nanowire polarization response, including the polarization response inversion. This work will open a new path towards the widespread implementation of nanowires applications such as in photodetection, solar energy harvesting and light emission. PMID:25564366

  14. Surface effects on large deflection of nanowires

    Institute of Scientific and Technical Information of China (English)

    杨帆

    2015-01-01

    Surface effects play an important role in the mechanical behavior of nanosized structural elements owing to the increased ratio of surface area to volume. The surface effects on the large deflection of nanowires were considered. Both geometric nonlinearity in finite deformation and surface effects at nanoscale were taken into account to analyze the bending of nanowires subjected to a concentrated force. For simply supported beams and clamped-clamped beams, the influence of surface effects and geometric nonlinearity were discussed in detail. It is found that both surface effects and geometric nonlinearity tend to decrease the deflection of bending nanowires and thus increase the effective elastic modulus of nanowires. Surface effects yield the size dependent behavior of nanowires.

  15. Nanowire-decorated microscale metallic electrodes

    DEFF Research Database (Denmark)

    Vlad, A.; Mátéfi-Tempfli, M.; Antohe, V.A.;

    2008-01-01

    The fabrication of metallic nanowire patterns within anodic alumina oxide (AAO) membranes on top of continuous conducting substrates are discussed. The fabrication protocol is based on the realization of nanowire patterns using supported nanoporous alumina templates (SNAT) prepared on top of...... lithographically defined metallic microelectrodes. The anodization of the aluminum permits electroplating only on top of the metallic electrodes, leading to the nanowire patterns having the same shape as the underlying metallic tracks. The variation in the fabricated structures between the patterned and non......-patterned substrates can be interpreted in terms of different behavior during anodization. The improved quality of fabricated nanowire patterns is clearly demonstrated by the SEM imaging and the uniform growth of nanowires inside the alumina template is observed without any significant height variation....

  16. Electrospun ZnO Nanowires as Gas Sensors for Ethanol Detection

    Directory of Open Access Journals (Sweden)

    Huang Po-Jung

    2009-01-01

    Full Text Available Abstract ZnO nanowires were produced using an electrospinning method and used in gas sensors for the detection of ethanol at 220 °C. This electrospinning technique allows the direct placement of ZnO nanowires during their synthesis to bridge the sensor electrodes. An excellent sensitivity of nearly 90% was obtained at a low ethanol concentration of 10 ppm, and the rest obtained at higher ethanol concentrations, up to 600 ppm, all equal to or greater than 90%.

  17. Bacterial hydrodynamics

    CERN Document Server

    Lauga, Eric

    2015-01-01

    Bacteria predate plants and animals by billions of years. Today, they are the world's smallest cells yet they represent the bulk of the world's biomass, and the main reservoir of nutrients for higher organisms. Most bacteria can move on their own, and the majority of motile bacteria are able to swim in viscous fluids using slender helical appendages called flagella. Low-Reynolds-number hydrodynamics is at the heart of the ability of flagella to generate propulsion at the micron scale. In fact, fluid dynamic forces impact many aspects of bacteriology, ranging from the ability of cells to reorient and search their surroundings to their interactions within mechanically and chemically-complex environments. Using hydrodynamics as an organizing framework, we review the biomechanics of bacterial motility and look ahead to future challenges.

  18. LEEM study of nucleation, growth, and decay of Ag nanowires on Cu(110)

    Science.gov (United States)

    Senevirathne, Indrajith; Bussmann, Ezra; Kellogg, Gary; Kurtz, Richard; Sprunger, Phillip

    2007-03-01

    Low energy electron microscopy (LEEM) has been used to study the nucleation, growth, and ripening of Ag nanowires on Cu(110). Previous STM and LEED studies of Ag on the Cu(110) surface have shown that for a Ag coverage of below 0.3 ML, Ag forms a surface alloy, followed by the formation of a 2D Ag(111) flat superstructure through dealloying at one monolayer. For Ag coverages above 1.3 ML , nanowires of Ag(110), with widths/heights of 12 nm / 2nm, grow along the [110] crystallographic direction with highly anisotropic aspect ratios. LEEM reveals that Ag initially alloys at Cu/Ag step edges producing a distortion of the steps. Upon deposition above 1 ML, nucleation of Ag nanowires was observed across terraces, however nucleation still occurred at defect and step edges. LEEM showed that the nanowires grow to micron lengths and have highly anisotropic aspect ratios. Annealing above 573K resulted in rapid Oswald ripening of nanowires to Ag clusters of several micron dimensions. Quantitative details of the growth and decay mechanisms will be discussed. Sandia Corporation is a Lockheed Martin Company, for the US DOE's NNSA under Contract DE-AC04-94AL85000. Work was supported CINT-U2006A123 and NSF-DMR-0504654.

  19. Acid-leached α-MnO2 nanowires for electrochemical energy storage

    Science.gov (United States)

    Byles, Bryan; Subramanian, Arunkumar; Pomerantseva, Ekaterina

    2014-09-01

    We present synthesis, acid-leaching, characterization and electrochemistry of α-MnO2 nanowires with tunnel crystal structure. This material is used as a matrix for lithium ions intercalation to provide insights into the effects of postsynthesis treatment on charge storage properties. Hydrothermal treatment of precursors produced 20 - 200 nm thick and tens of microns long nanowires. Acid leaching was carried out in the concentrated nitric acid at room temperature and resulted in the change of material composition and surface area. Original α-MnO2 nanowires showed initial discharge specific capacity of 96 mAh/g, while acid-leached material exhibited higher capacity values. This work forms the basis for future study aimed at understanding of correlation between crystal structure, composition and morphology of the "host" matrix and nature of the "guest" ions for beyond lithium electrochemical energy storage. In addition, we demonstrate single nanowire electrochemical cells for the study of electrochemically-correlated mechanical properties of the nanowires.

  20. Interference lithographically defined and catalytically etched, large-area silicon nanocones from nanowires.

    Science.gov (United States)

    Dawood, M K; Liew, T H; Lianto, P; Hong, M H; Tripathy, S; Thong, J T L; Choi, W K

    2010-05-21

    We report a simple and cost effective method for the synthesis of large-area, precisely located silicon nanocones from nanowires. The nanowires were obtained from our interference lithography and catalytic etching (IL-CE) method. We found that porous silicon was formed near the Au catalyst during the fabrication of the nanowires. The porous silicon exhibited enhanced oxidation ability when exposed to atmospheric conditions or in wet oxidation ambient. Very well located nanocones with uniform sharpness resulted when these oxidized nanowires were etched in 10% HF. Nanocones of different heights were obtained by varying the doping concentration of the silicon wafers. We believe this is a novel method of producing large-area, low cost, well defined nanocones from nanowires both in terms of the control of location and shape of the nanocones. A wide range of potential applications of the nanocone array can be found as a master copy for nanoimprinted polymer substrates for possible biomedical research; as a candidate for making sharp probes for scanning probe nanolithography; or as a building block for field emitting tips or photodetectors in electronic/optoelectronic applications. PMID:20418606

  1. The role of substrate surface alteration in the fabrication of vertically aligned CdTe nanowires.

    Science.gov (United States)

    Neretina, S; Hughes, R A; Devenyi, G A; Sochinskii, N V; Preston, J S; Mascher, P

    2008-05-01

    Previously we have described the deposition of vertically aligned wurtzite CdTe nanowires derived from an unusual catalytically driven growth mode. This growth mode could only proceed when the surface of the substrate was corrupted with an alcohol layer, although the role of the corruption was not fully understood. Here, we present a study detailing the remarkable role that this substrate surface alteration plays in the development of CdTe nanowires; it dramatically improves the size uniformity and largely eliminates lateral growth. These effects are demonstrated to arise from the altered surface's ability to limit Ostwald ripening of the catalytic seed material and by providing a surface unable to promote the epitaxial relationship needed to sustain a lateral growth mode. The axial growth of the CdTe nanowires is found to be exclusively driven through the direct impingement of adatoms onto the catalytic seeds leading to a self-limiting wire height associated with the sublimation of material from the sidewall facets. The work presented furthers the development of the mechanisms needed to promote high quality substrate-based vertically aligned CdTe nanowires. With our present understanding of the growth mechanism being a combination of selective area epitaxy and a catalytically driven vapour-liquid-solid growth mode, these results also raise the intriguing possibility of employing this growth mode in other material systems in an effort to produce superior nanowires. PMID:21825689

  2. The role of substrate surface alteration in the fabrication of vertically aligned CdTe nanowires

    International Nuclear Information System (INIS)

    Previously we have described the deposition of vertically aligned wurtzite CdTe nanowires derived from an unusual catalytically driven growth mode. This growth mode could only proceed when the surface of the substrate was corrupted with an alcohol layer, although the role of the corruption was not fully understood. Here, we present a study detailing the remarkable role that this substrate surface alteration plays in the development of CdTe nanowires; it dramatically improves the size uniformity and largely eliminates lateral growth. These effects are demonstrated to arise from the altered surface's ability to limit Ostwald ripening of the catalytic seed material and by providing a surface unable to promote the epitaxial relationship needed to sustain a lateral growth mode. The axial growth of the CdTe nanowires is found to be exclusively driven through the direct impingement of adatoms onto the catalytic seeds leading to a self-limiting wire height associated with the sublimation of material from the sidewall facets. The work presented furthers the development of the mechanisms needed to promote high quality substrate-based vertically aligned CdTe nanowires. With our present understanding of the growth mechanism being a combination of selective area epitaxy and a catalytically driven vapour-liquid-solid growth mode, these results also raise the intriguing possibility of employing this growth mode in other material systems in an effort to produce superior nanowires

  3. Small molecule control of bacterial biofilms

    OpenAIRE

    Worthington, Roberta J.; Richards, Justin J.; Melander, Christian

    2012-01-01

    Bacterial biofilms are defined as a surface attached community of bacteria embedded in a matrix of extracellular polymeric substances that they have produced. When in the biofilm state, bacteria are more resistant to antibiotics and the host immune response than are their planktonic counterparts. Biofilms are increasingly recognized as being significant in human disease, accounting for 80% of bacterial infections in the body and diseases associated with bacterial biofilms include: lung infect...

  4. Silver nanowires as catalytic cathodes for stabilizing lithium-oxygen batteries

    Science.gov (United States)

    Kwak, Won-Jin; Jung, Hun-Gi; Lee, Seon-Hwa; Park, Jin-Bum; Aurbach, Doron; Sun, Yang-Kook

    2016-04-01

    Silver nanowires have been investigated as a catalytic cathode material for lithium-oxygen batteries. Their high aspect ratio contributes to the formation of a corn-shaped layer structure of the poorly crystalline lithium peroxide (Li2O2) nanoparticles produced by oxygen reduction in poly-ether based electrolyte solutions. The nanowire morphology seems to provide the necessary large contact area and facile electron supply for a very effective oxygen reduction reaction. The unique morphology and structure of the Li2O2 deposits and the catalytic nature of the silver nano-wires promote decomposition of Li2O2 at low potentials (below 3.4 V) upon the oxygen evolution. This situation avoids decomposition of the solution species and oxidation of the electrodes during the anodic (charge) reactions, leading to high electrical efficiently of lithium-oxygen batteries.

  5. Multichannel nonlinear distortion compensation using optical phase conjugation in a silicon nanowire

    DEFF Research Database (Denmark)

    Vukovic, Dragana; Schoerder, Jochen; Da Ros, Francesco;

    2015-01-01

    We experimentally demonstrate compensation of nonlinear distortion caused by the Kerr effect in a 3 x 32-Gbaud quadrature phase-shift keying (QPSK) wavelength-division multiplexing (WDM) transmission system. We use optical phase conjugation (OPC) produced by four-wave mixing (FWM) in a 7-mm long...... silicon nanowire. A clear improvement in Q-factor is shown after 800-km transmission with high span input power when comparing the system with and without the optical phase conjugation module. The influence of OSNR degradation introduced by the silicon nanowire is analysed by comparing transmission...... systems of three different lengths. This is the first demonstration of nonlinear compensation using a silicon nanowire. (C)2015 Optical Society of America...

  6. Platinum nanowire microelectrode arrays for neurostimulation applications: Fabrication, characterization, and in-vitro retinal cell stimulation

    Science.gov (United States)

    Whalen, John J., III

    Implantable electrical neurostimulating devices are being developed for a number of applications, including artificial vision through retinal stimulation. The epiretinal prosthesis will use a two-dimensional array microelectrodes to address individual cells of the retina. MEMS fabrication processes can produce arrays of microelectrodes with these dimensions, but there are two critical issues that they cannot satisfy. One, the stimulating electrodes are the only part of the implanted electrical device that penetrate through the water impermeable package, and must do so without sacrificing hermeticity. Two, As electrode size decreases, the current density (A cm-2 ) increases, due to increased electrochemical impedance. This reduces the amount of charge that can be safely injected into the tissue. To date, MEMS processing method, cannot produce electrode arrays with good, prolonged hermetic properties. Similarly, MEMS approaches do not account for the increased impedance caused by decreased surface area. For these reasons there is a strong motivation for the development of a water-impermeable, substrate-penetrating electrode array with low electrochemical impedance. This thesis presents a stimulating electrode array fabricated from platinum nanowires using a modified electrochemical template synthesis approach. Nanowires are electrochemically deposited from ammonium hexachloroplatinate solution into lithographically patterned nanoporous anodic alumina templates to produce microarrays of platinum nanowires. The platinum nanowires penetrating through the ceramic aluminum oxide template serve as parallel electrical conduits through the water impermeable, electrically insulating substrate. Electrode impedance can be adjusted by either controlling the nanowire hydrous platinum oxide content or by partially etching the alumina template to expose additional surface area. A stepwise approach to this project was taken. First, the electrochemistry of ammonium

  7. Production and characterization of nanocomposite thin films based on Ni matrix reinforced with SnO{sub 2} single-crystalline nanowires for electrical contact applications

    Energy Technology Data Exchange (ETDEWEB)

    Miguel, F.L., E-mail: f.miguel@mx.uni-saarland.de [Saarland University, Functional Materials, 66123 Saarbrücken (Germany); Müller, R. [University of Cologne, Inorganic and Materials Chemistry, 50939 Cologne (Germany); Weinmann, M.; Hempelmann, R. [Saarland University, Physical Chemistry, 66123 Saarbrücken (Germany); Mathur, S. [University of Cologne, Inorganic and Materials Chemistry, 50939 Cologne (Germany); Mücklich, F. [Saarland University, Functional Materials, 66123 Saarbrücken (Germany)

    2014-08-01

    Highlights: • Metal-matrix nanocomposites obtained, reinforced by nanowires attached to substrate. • Nanocrystalline matrix in spite of direct-current electrodeposition being used. • Strong influence of SnO{sub 2} nanowires on surface and microstructural properties. • Previous coating of nanowires (with Ag) improved the matrix deposition. - Abstract: Nanocomposite thin films based on electrodeposited Ni matrix reinforced with SnO{sub 2} single-crystalline nanowires grown onto Si substrates by chemical vapor deposition were produced. The composites were characterized by means of scanning and transmission electron microscopy (for imaging, selected area diffraction and transmission Kikuchi diffraction), atomic force microscopy (for 3D surface profiling and roughness evaluation) and 4-point probe electrical resistivity measurements. The Ni matrices obtained were nanocrystalline in nature (41 nm crystallite mean size) even though low direct current electrodeposition was used. The topography and roughness of the samples were strongly affected by the presence of the nanowires as so was the electrical resistivity, which could be improved by Ag-coating the nanowires. A comparison with pure Ni produced in the same way is presented for determining the effects of the SnO{sub 2} nanowires.

  8. Synthesis and characterization of germanium nanowires and germanium/silicon radially heterostructured nanowires

    Science.gov (United States)

    Goldthorpe, Irene Anne

    Semiconductor nanowires offer new opportunities to study physical phenomena in low-dimensional nanostructures. They also possess technologically useful properties for applications in electronics, optics, sensing, and thermoelectrics. Germanium nanowires are of particular interest, because of germanium's compatibility with standard silicon integrated circuit fabrication processes, its high electronic carrier mobilities, and the low temperature required for germanium nanowire growth. In this work, epitaxially-aligned germanium nanowires are grown on silicon substrates by chemical vapor deposition through the vapor-liquid-solid mechanism. Uniform nanowire diameters between 5 and 50 nm are obtained through the use of monodisperse gold colloids as catalysts. The crystallographic orientation of the nanowires, their strain, and their heteroepitaxial relationship with the substrate are characterized with transmission electron microscopy (TEM) and x-ray diffraction (XRD). A process for removing the gold catalysts from the tips of the germanium nanowires is demonstrated. Silicon shells are then heteroepitaxially deposited around the wires to fabricate radial heterostructures. These shells passivate the germanium nanowire surface, create electronic band offsets to confine holes away the surface where they can scatter or recombine, and induce strain which could allow for the engineering of properties such as band gap and carrier mobilities. However, analogous to planar heteroepitaxy, surface roughening and misfit dislocations can relax this strain. The effects of coaxial dimensions on strain relaxation in these structures are analyzed quantitatively by TEM and synchrotron XRD, and these results are related to continuum elasticity models. Lessons learned generated two successful strategies for synthesizing coherent core-shell nanowires with large misfit strain: chlorine surface passivation and growth of nanowires with low-energy sidewall facets. Both approaches avoid the strain

  9. Effective surface anisotropy in polycrystalline ferromagnetic nanowires

    International Nuclear Information System (INIS)

    Highlights: • Here we make a mixing of two models. A macroscopic and a microscopic model. • The principal idea in this paper is to write the free magnetic energy for a soft magnetic cylindrical nanowire and make the comparison with our previous models. • The model is tested to determine the effective constant in Ni nanowires. - Abstract: Here we express the effective surface anisotropy for soft ferromagnetic nanowires as the function of the micro-structural behaviors. Many papers about these systems determine the reversal modes for the magnetization to explain magnetic properties of the nanowires. Our previous works related morphological structure with magnetic properties. The principal idea in this paper is to write the free magnetic energy for a soft magnetic cylindrical nanowire and make the comparison with our previous models. In this way we include the macroscopic effective anisotropy due to the disordered atoms and ignoring other microstructure terms related in our previous works. From this idea and our last model to these systems, we made an association that permit to express the effective anisotropy in function of the principal morphological characteristics of nanowires. The model is tested to determine the numerical value of the mentioned constant in Ni nanowires obtained by electrodeposition in porous anodic aluminum oxide membranes using the Transmission Electron Microscopy

  10. Review on photonic properties of nanowires for photovoltaics.

    Science.gov (United States)

    Mokkapati, S; Jagadish, C

    2016-07-25

    III-V semiconductor nanowires behave as optical antennae because of their shape anisotropy and high refractive index. The antennae like behavior modifies the absorption and emission properties of nanowires compared to planar materials. Nanowires absorb light more efficiently compared to an equivalent volume planar material, leading to higher short circuit current densities. The modified emission from the nanowires has the potential to increase the open circuit voltage from nanowire solar cells compared to planar solar cells. In order to achieve high efficiency nanowire solar cells it is essential to control the surface state density and doping in nanowires. We review the physics of nanowire solar cells and progress made in addressing the surface recombination and doping of nanowires, with emphasis on GaAs and InP materials. PMID:27464182

  11. Optimised quantum hacking of superconducting nanowire single-photon detectors

    Science.gov (United States)

    Tanner, Michael G.; Makarov, Vadim; Hadfield, Robert H.

    2014-03-01

    We explore bright-light control of superconducting nanowire single-photon detectors (SNSPDs) in the shunted configuration (a practical measure to avoid latching). In an experiment, we simulate an illumination pattern the SNSPD would receive in a typical quantum key distribution system under hacking attack. We show that it effectively blinds and controls the SNSPD. The transient blinding illumination lasts for a fraction of a microsecond and produces several deterministic fake clicks during this time. This attack does not lead to elevated timing jitter in the spoofed output pulse, and hence does not introduce significant errors. Five different SNSPD chip designs were tested. We consider possible countermeasures to this attack.

  12. Alignment nature of ZnO nanowires grown on polished and nanoscale etched lithium niobate surface through self-seeding thermal evaporation method

    International Nuclear Information System (INIS)

    Highlights: • ZnO nanowires were grown directly on LiNbO3 surface for the first time by thermal evaporation. • Self-alignment of the nanowires due to step bunching of LiNbO3 surface is observed. • Increased roughness in surface defects promoted well-aligned growth of nanowires. • Well-aligned growth was then replicated in 50 nm deep trenches on the surface. • Study opens novel pathway for patterned growth of ZnO nanowires on LiNbO3 surface. - Abstract: High aspect ratio catalyst-free ZnO nanowires were directly synthesized on lithium niobate substrate for the first time through thermal evaporation method without the use of a buffer layer or the conventional pre-deposited ZnO seed layer. As-grown ZnO nanowires exhibited a crisscross aligned growth pattern due to step bunching of the polished lithium niobate surface during the nanowire growth process. On the contrary, scratches on the surface and edges of the substrate produced well-aligned ZnO nanowires in these defect regions due to high surface roughness. Thus, the crisscross aligned nature of high aspect ratio nanowire growth on the lithium niobate surface can be changed to well-aligned growth through controlled etching of the surface, which is further verified through reactive-ion etching of lithium niobate. The investigations and discussion in the present work will provide novel pathway for self-seeded patterned growth of well-aligned ZnO nanowires on lithium niobate based micro devices

  13. Sensitive optical switch based on Bi2S3 single nanowire and nanowire film

    International Nuclear Information System (INIS)

    Highlights: • A single Bi2S3 nanowire photoelectric device is fabricated. • Focused ion beam is used to deposit Ga induced Pt on the contacts between the nanowire and Au electrode. • The photoelectric properties of the devices are studied. • Single Bi2S3 nanowire devices show better performances compared with Bi2S3 thin film device. - Abstract: Long and high quality Bi2S3 nanowires (NWs) were obtained by a modified composite molten salt method. A single nanowire photoelectric device was fabricated by bridging a single Bi2S3 NW across two Au electrodes, and focused ion beam (FIB) was used to deposit Pt on the two contacts between the nanowire and the Au electrode for forming Ohmic contacts. For comparison another single nanowire device was made without using FIB. Photoelectric properties of the two devices were systematically investigated under simulation sunlight illumination at room temperature in the open air. Both single nanowire devices exhibit high sensitive photoelectric responses that are fully reversible and periodic. The device with the deposition of Pt shows a better stability than that of the device without deposition of Pt. In addition, both single nanowire devices exhibit better performance compared with the thin film device made of Bi2S3 NWs. The results imply that single Bi2S3 NW device is a promising candidate for fabricating optical detectors or optical switches

  14. 68株北极产蛋白酶菌株的筛选、鉴定以及部分酶学性质%Isolation, identification and characterization of 68protease-producing bacterial strains from the Arctic

    Institute of Scientific and Technical Information of China (English)

    陈明霞; 李和阳; 陈维维; 刁伟程; 刘承忠; 袁敏; 李晓虹

    2013-01-01

    [目的]从北极海水样品中分离产蛋白酶细菌,并对其进行初步的分类鉴定,为低温蛋白酶的低温适应性及其应用研究奠定基础.[方法]通过酪蛋白筛选培养基低温培养的方法从北极水样中分离出68株产蛋白酶细菌,采用16S rRNA基因PCR-RFLP(限制性酶切多态性)方法及传统的表型特性分析对所分离纯化的菌株进行分类,每种细菌类型各取1株代表菌株进行16S rRNA基因序列测定、GenBank数据库blast分析以及通过DNAMAN软件进行系统进化树分析.对代表菌株的蛋白酶酶学性质进行初步研究.[结果]68个菌株可归为3种类型(54.41%、42.65%和2.94%),分别以菌株6、11和52为代表菌株.16S rRNA基因序列分析结果表明,菌株11与比目鱼黄杆菌(Chryseobacterium scophthalmum)具有98.24%的同源性;菌株52与嗜根寡养单胞菌(Stenotrophomonas rhizophila)具有98.55%的同源性;菌株6与Stenotrophomonas rhizophila具有96.50%的同源性,可能为该属的新物种.对3种类型代表菌株进行表型性状研究显示,菌株6、1 1和52为革兰氏阴性、直杆状、不产胞外脂肪酶和淀粉酶,具有强的蛋白酶活性.菌株6的蛋白酶最适酶活温度为55℃,最适宜pH为6.7;菌株1 1的蛋白酶最适酶活温度为40℃,属于低温酶,最适酶活pH约为8.5;菌株52的蛋白酶最适酶活温度为65℃,最适酶活pH为7.4.[结论]本文首次报道了Stenotrophomonas和C hryseobacterium的菌株在北极海水样品中的分布,充实了极地产蛋白酶菌的种属分布多样性,为后续低温蛋白酶的研究和应用奠定了基础.%[Objective] We screened and identified protease-producing bacterial strains from the Arctic,the results would help find cold-adapted protease.[Methods] In total 68 protease-producing strains were screened from the Arctic using the casein-agar plate under low temperature.All strains were classified using the 16S rRNA gene-restriction fragment

  15. Molten salt solvent synthesis of La2Mo2O9 nano-wires by controlling the subsequent calcinations process

    International Nuclear Information System (INIS)

    Large amounts of La2Mo2O9 nano-wires have been produced using molten-salt synthesis method. The powder X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy are used to investigate structure and morphological features of the obtained products. The formed nano-wires have an average diameter of about 100 nm and a length in the range from ten to several tens of micrometers. The analyses of the high resolution transmission electron microscopy and the selected area electron diffraction results show that the nano-wires are single crystalline and grow along the [0 0 1] direction. A growth mechanism of La2Mo2O9 nano-wires is also proposed in this report. It implies that the temperature, chloride ions and cation lattice in β-La2Mo2O9 might be related to the particles morphologies transition. - Highlights: • La2Mo2O9nano-wires are successfully synthesizedand first reported in this paper. • The influences of possible factors on nano-wires synthesis are discussed. • The possible mechanism was discussed

  16. Hydrothermal synthesis and characterization of self-assembled h-WO3 nanowires/nanorods using EDTA salts

    International Nuclear Information System (INIS)

    One-dimensional (1D) self-assembled single-crystalline hexagonal tungsten oxide (h-WO3) nanostructures were synthesized by a hydrothermal method at 180 deg. C using sodium tungstate, ethylenediaminetetraacetic (EDTA) salts of sodium or ammonium, and sodium sulfate. Controlled morphological modification of h-WO3 nanowire bundles was achieved and hierarchical urchin-like structures were produced by simply substituting the sodium ions with ammonium ions in the EDTA salt solution. Self-assembled h-WO3 nanowire bundles and nanorods that formed urchin-like structures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. 1D self-assembled h-WO3 nanowire bundles of ∼100 nm diameter and 1-2 μm length were comprised of several individual uniform nanowires of 4-6 nm diameter. These individual nanowires served as building blocks of the bundles. Raman, cyclic voltammetry (CV), and photoluminescence (PL) spectroscopy studies revealed their structure, electrochemical response, and luminescence properties. The synthesis of 1D self-assembled h-WO3 nanowire bundles and urchin-like structures was differentiated by means of Na+- and NH4+-based EDTA salt solutions.

  17. 饵料对蚯蚓粪细菌群落结构多样性的影响%Characterization of Bacterial Community Diversity in Various Vermicomposts Produced from Feedstocks

    Institute of Scientific and Technical Information of China (English)

    陈浩; 赵海涛; 姚振飞; 孙红军; 胡健

    2012-01-01

    以牛粪、猪粪和污泥等有机废弃物作为蚯蚓饵料,利用细菌16S rDNA V3区特异扩增及变性梯度凝胶电泳(PCR-DGGE)技术,比较了不同饵料及饵料改变对蚯蚓粪细菌群落结构多样性的影响.结果表明:(1)与所取食的饵料相比,蚯蚓粪细菌群落结构多样性均有不同程度的下降,蚯蚓粪与对应饵料之间细菌群落结构相似性范围为15.3%~37.7%;(2)来自不同饵料的蚯蚓粪细菌群落结构相似性范围为17.2%~39.1%,其中以牛粪和猪粪为饵料时,蚯蚓粪细菌群落结构相似性最高,与对应的饵料细菌群落结构相似性相比,提高了近1倍;(3)当饵料由猪粪改为牛粪后,随着时间延长,蚯蚓粪细菌群落结构多样性逐渐下降并趋于稳定,并且蚯蚓粪与饵料牛粪的细菌群落结构相似性由0d的33.2%逐渐下降到21d的14.8%并趋于稳定.由此可知,饵料的种类及转换可以影响蚯蚓粪细菌群落结构多样性.%The earthworms were fed with different feedstocks, such as cattle manure, pig manure and sludge. Then the bacterial community diversity between feedstock and vermicompost were determined by DGGE analysis of PCR-amplified bacterial 16S rDNA V3 region. The results showed that: (1 )The diversities of bacterial community in various vermicomposts were all decreased as compared with different feedstocks. The similarity coefficients of the bacterial community between vermicompost and feedstock were different among all the tested samples, which were from 15.3% to 37.7%;(2)Feeding with different kind of feedstocks resulted in the different similarity coefficient of bacteria] community among all the types of vermicomposts, but some vermicompost samples showed similar bacterial community diversity. The highest similarity value was found between two vermicomposts derived from cattle manure and pig manure, respectively, both of which were about one fold higher than their corresponding feedstocks;( 3 )The

  18. Rare earth silicide nanowires on silicon surfaces

    International Nuclear Information System (INIS)

    The growth, structure and electronic properties of rare earth silicide nanowires are investigated on planar and vicinal Si(001) und Si(111) surfaces with scanning tunneling microscopy (STM), low energy electron diffraction (LEED) and angle-resolved photoelectron spectroscopy (ARPES). On all surfaces investigated within this work hexagonal disilicides are grown epitaxially with a lattice mismatch of -2.55% up to +0.83% along the hexagonal a-axis. Along the hexagonal c-axis the lattice mismatch is essentially larger with 6.5%. On the Si(001)2 x 1 surface two types of nanowires are grown epitaxially. The socalled broad wires show a one-dimensional metallic valence band structure with states crossing the Fermi level. Along the nanowires two strongly dispersing states at the anti J point and a strongly dispersing state at the anti Γ point can be observed. Along the thin nanowires dispersing states could not be observed. Merely in the direction perpendicular to the wires an intensity variation could be observed, which corresponds to the observed spacial structure of the thin nanowires. The electronic properties of the broad erbium silicide nanowires are very similar to the broad dysprosium silicide nanowires. The electronic properties of the DySi2-monolayer and the Dy3Si5-multilayer on the Si(111) surface are investigated in comparison to the known ErSi2/Si(111) and Er3Si5/Si(111) system. The positions and the energetic locations of the observed band in the surface Brillouin zone will be confirmed for dysprosium. The shape of the electron pockets in the vector k parallel space is elliptical at the anti M points, while the hole pocket at the anti Γ point is showing a hexagonal symmetry. On the Si(557) surface the structural and electronic properties depend strongly on the different preparation conditions likewise, in particular on the rare earth coverage. At submonolayer coverage the thin nanowires grow in wide areas of the sample surface, which are oriented in the same

  19. Mechanical properties of Silicon Carbide Nanowires

    Science.gov (United States)

    Alkhateeb, Abdullah; Zhang, Daqing; McIlroy, David; Aston, David Eric

    2004-05-01

    Silicon carbide nanowires could be potentially useful for high strength materials which lead to the interest in understanding their mechanical properties. In this report we use the digital pulse force microscopy to analyze the mechanical properties of SiC nanowires .Stiffness and adhesion images of SiC nanowires on silicon grating were obtained and calibrated force-distance curves were plotted along the wire which spans on a 1.5 micron trench. Moreover, spring constant and Young's modules have been calculated from the linear part of the force-distance curves.

  20. Encoding Active Device Elements at Nanowire Tips.

    Science.gov (United States)

    No, You-Shin; Gao, Ruixuan; Mankin, Max N; Day, Robert W; Park, Hong-Gyu; Lieber, Charles M

    2016-07-13

    Semiconductor nanowires and other one-dimensional materials are attractive for highly sensitive and spatially confined electrical and optical signal detection in biological and physical systems, although it has been difficult to localize active electronic or optoelectronic device function at one end of such one-dimensional structures. Here we report a new nanowire structure in which the material and dopant are modulated specifically at only one end of nanowires to encode an active two-terminal device element. We present a general bottom-up synthetic scheme for these tip-modulated nanowires and illustrate this with the synthesis of nanoscale p-n junctions. Electron microscopy imaging verifies the designed p-Si nanowire core with SiO2 insulating inner shell and n-Si outer shell with clean p-Si/n-Si tip junction. Electrical transport measurements with independent contacts to the p-Si core and n-Si shell exhibited a current rectification behavior through the tip and no detectable current through the SiO2 shell. Electrical measurements also exhibited an n-type response in conductance versus water-gate voltage with pulsed gate experiments yielding a temporal resolution of at least 0.1 ms and ∼90% device sensitivity localized to within 0.5 μm from the nanowire p-n tip. In addition, photocurrent experiments showed an open-circuit voltage of 0.75 V at illumination power of ∼28.1 μW, exhibited linear dependence of photocurrent with respect to incident illumination power with an estimated responsivity up to ∼0.22 A/W, and revealed localized photocurrent generation at the nanowire tip. The tip-modulated concept was further extended to a top-down/bottom-up hybrid approach that enabled large-scale production of vertical tip-modulated nanowires with a final synthetic yield of >75% with >4300 nanowires. Vertical tip-modulated nanowires were fabricated into >50 individually addressable nanowire device arrays showing diode-like current-voltage characteristics. These tip

  1. Magnetic nanowire-enhanced optomagnetic tweezers

    Science.gov (United States)

    Mehta, Karan K.; Wu, Ting-Hsiang; Chiou, Eric P. Y.

    2008-12-01

    We report an optomagnetic tweezers technique that utilizes the highly localized magnetic field gradients induced near the tip of a magnetic nanowire to provide strong trapping forces on magnetic nanoparticles with high spatial resolution. Integral to our approach is a method to trap, translate, and rotate a single magnetic nanowire in three dimensions. Our simulation predicts that forces in the range of 100 pN can be generated on 200 nm magnetic particles within 0.2 μm from a 200 nm diameter nickel nanowire. Such forces are relevant in many biological processes, suggesting that this approach will be of value in biophysical studies.

  2. Growth and characterization of semiconductor nanowires

    Science.gov (United States)

    Philipose, Usha

    This thesis describes a catalytic growth approach to synthesize semiconductor nanowires with good control over their physical dimensions, chemical composition, and optical/electronic properties. Using the Vapour-Liquid-Solid growth mechanism, gold nanoclusters serve as the catalytic sites directing the growth of crystalline Zinc Selenide (ZnSe), Zinc Oxide (ZnO) and Zinc Sulphide (ZnS) nanowires with length of several microns and diameters varying from 15 nm to 100 nm. The morphology and properties of the nanowires were found to be strongly dependent on growth conditions. Optical characterization by photoluminescence spectroscopy show that the spectra is dominated by near band edge emission for low defect density nanowires in contrast to the high level of defect related emission from high defect density nanowires. The growth parameters were optimized leading to the synthesis of nanowires with minimum defect concentration. Electrical transport studies on an array of ZnSe nanowires confirm that there exists a non-uniform carrier distribution along the nanowires leading to 'super-linear' current-voltage behaviour with carrier mobilities comparable to that of bulk material. Photoconductivity measurements on ZnSe nanoribbons show that they are of good quality, enabling realization of a nanoscale photodetector with a peak efficiency of 43%. Spectral response of photoconductivity had a threshold character with edge corresponding to the ZnSe bandgap, which makes it an ideal candidate for blue and ultraviolet light detection. The effect of doping of these nanowires with transition elements such as manganese (Mn) has been studied. In this effort, the first successful attempt at synthesizing room temperature ferromagnetic nanowires has been realized. Above room temperature ferromagnetism has been observed for the first time in dilute Mn-doped crystalline ZnO nanowires. From the observed saturation magnetization, the magnetic moment per Mn atom is estimated to be in the range

  3. Semiconductor Nanowires: What's Next?

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Peidong; Yan, Ruoxue; Fardy, Melissa

    2010-04-28

    In this perspective, we take a critical look at the research progress within the nanowire community for the past decade. We discuss issues on the discovery of fundamentally new phenomena versus performance benchmarking for many of the nanowire applications. We also notice that both the bottom-up and top-down approaches have played important roles in advancing our fundamental understanding of this new class of nanostructures. Finally we attempt to look into the future and offer our personal opinions on what the future trends will be in nanowire research.

  4. Optical Properties of Rotationally Twinned Nanowire Superlattices

    DEFF Research Database (Denmark)

    Bao, Jiming; Bell, David C.; Capasso, Federico;

    2008-01-01

    We have developed a technique so that both transmission electron microscopy and microphotoluminescence can be performed on the same semiconductor nanowire over a large range of optical power, thus allowing us to directly correlate structural and optical properties of rotationally twinned zinc...... blende InP nanowires. We have constructed the energy band diagram of the resulting multiquantum well heterostructure and have performed detailed quantum mechanical calculations of the electron and hole wave functions. The excitation power dependent blue-shift of the photoluminescence can be explained in...... heterostructure in a chemically homogeneous nanowire material and alter in a major way its optical properties opens new possibilities for band-structure engineering....

  5. Preparation of Metal Nanowire Decorated Carbon Allotropes

    Science.gov (United States)

    Southward, Robin E. (Inventor); Delozier, Donavon Mark (Inventor); Watson, Kent A. (Inventor); Smith, Joseph G. (Inventor); Ghose, Sayata (Inventor); Connell, John W. (Inventor)

    2014-01-01

    In the method of embodiments of the invention, the metal seeded carbon allotropes are reacted in solution forming zero valent metallic nanowires at the seeded sites. A polymeric passivating reagent, which selects for anisotropic growth is also used in the reaction to facilitate nanowire formation. The resulting structure resembles a porcupine, where carbon allotropes have metallic wires of nanometer dimensions that emanate from the seed sites on the carbon allotrope. These sites are populated by nanowires having approximately the same diameter as the starting nanoparticle diameter.

  6. Electrodeposited L10 CoPt nanowires

    DEFF Research Database (Denmark)

    Mallet, J.; Yu-Zhang, K.; Mátéfi-Tempfli, Stefan;

    2005-01-01

    Arrays of face-centred cubic (fee) CoPt (0.45 nanowires were electrodeposited into thin film nanoporous alumina supported on a Si substrate. The heat treatment under specific conditions was then carried out in order to transform the fee phase into the face-centred tetragonal or L1 ordered...... phase. The influence of both the phase transition and the temperature on the magnetic properties of Co Pt nanowires has been studied. Coercive fields higher than 1 T (10kOe) have been obtained at room temperature with ordered nanowires, 80 nm in diameter. © 2005 IOP Publishing Ltd....

  7. Smooth-surface silver nanowire electrode with high conductivity and transparency on functional layer coated flexible film

    Energy Technology Data Exchange (ETDEWEB)

    Lee, So Hee; Lim, Sooman; Kim, Haekyoung, E-mail: hkkim@ynu.ac.kr

    2015-08-31

    Transparent conductive electrode (TCE) with silver nanowires has been widely studied as an alternative of indium tin oxide for flexible electronic or optical devices such as organic light-emitting diodes, and solar cells. However, it has an issue of surface roughness due to nanowire's intrinsic properties. Here, to achieve a smooth electrode with high conductivity and transmittance on polyethylene terephthalate (PET) substrates, a functional layer of poly(N-vinylpyrrolidone) (PVP) is utilized with a mechanical transfer process. The silver nanowire electrode on PVP-coated PET with low surface roughness of 9 nm exhibits the low sheet resistance of 18 Ω □{sup −1} and high transmittance of 87.6%. It is produced by transferring the silver nanowire electrode spin-coated on the glass to PVP-coated PET using a pressure of 10 MPa for 10 min. Silver nanowire electrode on PVP-coated PET demonstrates the stable sheet resistance of 18 Ω □{sup −1} after the mechanical taping test due to strong adhesion between PVP functional layer and silver nanowires. Smooth TCE with silver nanowires could be proposed as a transparent electrode for flexible electronic or optical devices, which consist of thin electrical active layers on TCE. - Highlights: • Silver nanowire (Ag NWs) transparent electrodes were fabricated on flexible film. • Flexible film was coated with poly N-vinylpyrrolidone (PVP). • PVP layer plays roles as an adhesive layer and matrix in electrode. • Ag NWs electrode exhibited with low surface roughness of 9 nm. • Ag NWs electrode has a low resistance (18 Ω ☐{sup −1}) and high transmittance (87.6%)

  8. Smooth-surface silver nanowire electrode with high conductivity and transparency on functional layer coated flexible film

    International Nuclear Information System (INIS)

    Transparent conductive electrode (TCE) with silver nanowires has been widely studied as an alternative of indium tin oxide for flexible electronic or optical devices such as organic light-emitting diodes, and solar cells. However, it has an issue of surface roughness due to nanowire's intrinsic properties. Here, to achieve a smooth electrode with high conductivity and transmittance on polyethylene terephthalate (PET) substrates, a functional layer of poly(N-vinylpyrrolidone) (PVP) is utilized with a mechanical transfer process. The silver nanowire electrode on PVP-coated PET with low surface roughness of 9 nm exhibits the low sheet resistance of 18 Ω □−1 and high transmittance of 87.6%. It is produced by transferring the silver nanowire electrode spin-coated on the glass to PVP-coated PET using a pressure of 10 MPa for 10 min. Silver nanowire electrode on PVP-coated PET demonstrates the stable sheet resistance of 18 Ω □−1 after the mechanical taping test due to strong adhesion between PVP functional layer and silver nanowires. Smooth TCE with silver nanowires could be proposed as a transparent electrode for flexible electronic or optical devices, which consist of thin electrical active layers on TCE. - Highlights: • Silver nanowire (Ag NWs) transparent electrodes were fabricated on flexible film. • Flexible film was coated with poly N-vinylpyrrolidone (PVP). • PVP layer plays roles as an adhesive layer and matrix in electrode. • Ag NWs electrode exhibited with low surface roughness of 9 nm. • Ag NWs electrode has a low resistance (18 Ω ☐−1) and high transmittance (87.6%)

  9. Fabrication and properties of silicon carbide nanowires

    Science.gov (United States)

    Shim, Hyun Woo

    2008-12-01

    Silicon carbide (SiC), with excellent electrical, thermal, and mechanical properties, is a promising material candidate for future devices such as high-temperature electronics and super-strong lightweight structures. Combined with superior intrinsic properties, the nanomaterials of SiC show further advantages thanks to nanoscale effects. This thesis reports the growth mechanism, the self-integration, and the friction of SiC nanowires. The study involves nanowires fabrication using thermal evaporation, structure characterization using electron microscopy, friction measurement, and theoretical modeling. The study on nanowire growth mechanism requires understanding of the surfaces and interfaces of nanowire crystal. The catalyzed growth of SiC nanowires involves interfaces between source vapor, catalytic liquid, and nanowire solid. Our experimental observation includes the periodical twinning in a faceted SiC nanowire and three stage structure transitions during the growth. The proposed theoretical model shows that such phenomenon is the result of surface energy minimization process during the catalytic growth. Surface interactions also exist between nanowires, leading to their self-integration. Our parametric growth study reveals novel self-integration of SiC-SiO 2 core-shell nanowires as a result of SiO2 joining. Attraction between nanowires through van der Waals force and enhanced SiO2 diffusion at high temperature transform individual nanowires to the integrated nanojunctions, nanocables, and finally nanowebs. We also show that such joining process becomes effective either during growth or by annealing. The solid friction is a result of the interaction between two solid surfaces, and it depends on the adhesion and the deformation of two contacting solids among other factors. Having strong adhesion as shown from gecko foot-hairs, nanostructured materials should also have strong friction; this study is the first to investigate friction of nanostructures under

  10. Direct laser fabrication of nanowires on semiconductor surfaces

    Science.gov (United States)

    Haghizadeh, Anahita; Yang, Haeyeon

    2016-03-01

    Periodic nanowires are observed from (001) orientation of Si and GaAs when the surfaces are irradiated interferentially by high power laser pulses. These nanowires are self-assembled and can be strain-free while their period is consistent with interference period. The nanowire morphologies are studied by atomic force microscopy. The observed period between nanowires depends on the wavelengths used and interference angle. The nanowire width increases with laser intensity. The narrowest nanowires observed have the width smaller than 20 nm, which is more than 10 times smaller than the interference period.

  11. Twinning effect on photoluminescence spectra of ZnSe nanowires

    International Nuclear Information System (INIS)

    Bandgap engineering in a single material along the axial length of nanowires may be realized by arranging periodic twinning, whose twin plane is vertical to the axial length of nanowires. In this paper, we report the effect of twin on photoluminescence of ZnSe nanowires, which refers to the bandgap of it. The exciton-related emission peaks of transverse twinning ZnSe nanowires manifest a 10-meV-blue-shift in comparison with those of longitudinal twinning ZnSe nanowires. The blue-shift is attributed to quantum confinement effect, which is influenced severely by the proportion of wurtzite ZnSe layers in ZnSe nanowires.

  12. Biofunctionalization of zinc oxide nanowires for DNA sensory applications

    Directory of Open Access Journals (Sweden)

    Rudolph Bettina

    2011-01-01

    Full Text Available Abstract We report on the biofunctionalization of zinc oxide nanowires for the attachment of DNA target molecules on the nanowire surface. With the organosilane glycidyloxypropyltrimethoxysilane acting as a bifunctional linker, amino-modified capture molecule oligonucleotides have been immobilized on the nanowire surface. The dye-marked DNA molecules were detected via fluorescence microscopy, and our results reveal a successful attachment of DNA capture molecules onto the nanowire surface. The electrical field effect induced by the negatively charged attached DNA molecules should be able to control the electrical properties of the nanowires and gives way to a ZnO nanowire-based biosensing device.

  13. Growth of Silicon Nanowires by Heating Si Substrate

    Institute of Scientific and Technical Information of China (English)

    邢英杰; 奚中和; 俞大鹏; 杭青岭; 严涵斐; 冯孙齐; 薛增泉

    2002-01-01

    Amorphous silicon nanowires were prepared by heating an Si substrate at high temperatures using an Ni (or Au) catalyst. The nanowires have a diameter of 10 - 40nm and a length of up to several tens of micrometres.Unlike the well-known vapour-liquid-solid mechanism, a solid-liquid-solid mechanism appeared to control the nanowire growth. The heating process had a strong influence on the growth of silicon nanowires. It was found that ambient gas was necessary to grow nanowires. This method can be used to prepare other kinds of nanowires.

  14. Coupling of Semiconductor Nanowires with Neurons and Their Interfacial Structure

    Directory of Open Access Journals (Sweden)

    Rhim Hyewhon

    2009-01-01

    Full Text Available Abstract We report on the compatibility of various nanowires with hippocampal neurons and the structural study of the neuron–nanowire interface. Si, Ge, SiGe, and GaN nanowires are compatible with hippocampal neurons due to their native oxide, but ZnO nanowires are toxic to neuron due to a release of Zn ion. The interfaces of fixed Si nanowire and hippocampal neuron, cross-sectional samples, were prepared by focused ion beam and observed by transmission electron microscopy. The results showed that the processes of neuron were adhered well on the nanowire without cleft.

  15. Topological Insulator Nanowires and Nanoribbons

    KAUST Repository

    Kong, Desheng

    2010-01-13

    Recent theoretical calculations and photoemission spectroscopy measurements on the bulk Bi2Se3 material show that it is a three-dimensional topological insulator possessing conductive surface states with nondegenerate spins, attractive for dissipationless electronics and spintronics applications. Nanoscale topological insulator materials have a large surface-to-volume ratio that can manifest the conductive surface states and are promising candidates for devices. Here we report the synthesis and characterization of high quality single crystalline Bi2Se5 nanomaterials with a variety of morphologies. The synthesis of Bi 2Se5 nanowires and nanoribbons employs Au-catalyzed vapor-liquid-solid (VLS) mechanism. Nanowires, which exhibit rough surfaces, are formed by stacking nanoplatelets along the axial direction of the wires. Nanoribbons are grown along [1120] direction with a rectangular cross-section and have diverse morphologies, including quasi-one-dimensional, sheetlike, zigzag and sawtooth shapes. Scanning tunneling microscopy (STM) studies on nanoribbons show atomically smooth surfaces with ∼ 1 nm step edges, indicating single Se-Bi-Se-Bi-Se quintuple layers. STM measurements reveal a honeycomb atomic lattice, suggesting that the STM tip couples not only to the top Se atomic layer, but also to the Bi atomic layer underneath, which opens up the possibility to investigate the contribution of different atomic orbitais to the topological surface states. Transport measurements of a single nanoribbon device (four terminal resistance and Hall resistance) show great promise for nanoribbons as candidates to study topological surface states. © 2010 American Chemical Society.

  16. Ion beam processing of Au nanowires

    International Nuclear Information System (INIS)

    In nanoelectronics a nanowire forms an elemental building block enabling a charge transfer in complex nanostructures. Ion beam etching has been applied for downsizing of prefabricated Au nanowires in the sub-50 nm linewidth regime, aiming at achieving effective cross sections of less than 10 nm. Low energy Ar+ and Ga+ ions were employed for dry ion beam etching of Au nanowires. Nanometer-precise gradual downsizing to an effective diameter as small as 9 nm has been achieved when using Ar+ ions. In contrast, the chemical nature of Ga and its surface condensation into a nanosized phase turned out to act destructively on the nanowires' morphology, hampering the process of downsizing. In the surface nanocondensate Ga was found to coexist in both solid and liquid states, exhibiting polymorphism and peculiar dynamics under ion irradiation.

  17. Electrodeposition and Characterization of Bismuth Telluride Nanowires

    Science.gov (United States)

    Frantz, C.; Stein, N.; Gravier, L.; Granville, S.; Boulanger, C.

    2010-09-01

    In this work, we report thermoelectric measurements on electroplated bismuth telluride nanowires. Porous polycarbonate membranes, obtained by ion-track irradiation lithography, were chosen as electroplating templates. Bismuth telluride nanowires were achieved in acidic media under potentiostatic conditions at -100 mV versus saturated silver chloride electrode. The filling ratio of the pores was increased to 80% by adding dimethyl sulfoxide to the electrolyte. Whatever the experimental conditions, the nanowires were polycrystalline in the rhombohedral phase of Bi2Te3. Finally, the power output of arrays of bismuth telluride nanowires was analyzed as a function of load resistance. The results were strongly dependent on the internal resistance, which can be significantly reduced by the presence of dimethyl sulfoxide during electroplating.

  18. Superconducting nanowire single-photon imager

    CERN Document Server

    Zhao, Qing-Yuan; Calandri, Niccolò; Dane, Andrew E; McCaughan, Adam N; Bellei, Francesco; Wang, Hao-Zhu; Santavicca, Daniel F; Berggren, Karl K

    2016-01-01

    Detecting spatial and temporal information of individual photons is a crucial technology in today's quantum information science. Among the existing single-photon detectors, superconducting nanowire single-photon detectors (SNSPDs) have been demonstrated with a sub-50 ps timing jitter, near unity detection efficiency1, wide response spectrum from visible to infrared and ~10 ns reset time. However, to gain spatial sensitivity, multiple SNSPDs have to be integrated into an array, whose spatial and temporal resolutions are limited by the multiplexing circuit. Here, we add spatial sensitivity to a single nanowire while preserving the temporal resolution from an SNSPD, thereby turning an SNSPD into a superconducting nanowire single-photon imager (SNSPI). To achieve an SNSPI, we modify a nanowire's electrical behavior from a lumped inductor to a transmission line, where the signal velocity is slowed down to 0.02c (where c is the speed of light). Consequently, we are able to simultaneously read out the landing locati...

  19. Preparation of Ni/Cu composite nanowires

    Directory of Open Access Journals (Sweden)

    Hu Wang

    2015-06-01

    Full Text Available Ni/Cu composite nanowires were synthesized in an aqueous solution for the first time. The synthetic process consisted of two steps. Firstly, pure nickel nanowires were prepared through chemical reduction in solution under a magnetic field. Secondly, copper was reduced on the surface of the nickel nanowires, during which Ni/Cu composite nanowires with an average length of 80 µm and diameter of about 200 nm were synthesized. The products were characterized by XRD, SEM and TEM. The method has notable advantages: It is template-free, inexpensive, easy-to-operate, and it only needs a short reaction time, which makes it suitable for large-scale preparation.

  20. Boron carbide nanowires: Synthesis and characterization

    Science.gov (United States)

    Guan, Zhe

    Bulk boron carbide has been widely used in ballistic armored vest and the property characterization has been heavily focused on mechanical properties. Even though boron carbides have also been projected as a promising class of high temperature thermoelectric materials for energy harvesting, the research has been limited in this field. Since the thermal conductivity of bulk boron carbide is still relatively high, there is a great opportunity to take advantage of the nano effect to further reduce it for better thermoelectric performance. This dissertation work aims to explore whether improved thermoelectric performance can be found in boron carbide nanowires compared with their bulk counterparts. This dissertation work consists of four main parts. (1) Synthesis of boron carbide nanowires. Boron carbide nanowires were synthesized by co-pyrolysis of diborane and methane at low temperatures (with 879 °C as the lowest) in a home-built low pressure chemical vapor deposition (LPCVD) system. The CVD-based method is energy efficient and cost effective. The as-synthesized nanowires were characterized by electron microscopy extensively. The transmission electron microscopy (TEM) results show the nanowires are single crystalline with planar defects. Depending on the geometrical relationship between the preferred growth direction of the nanowire and the orientation of the defects, the as-synthesized nanowires could be further divided into two categories: transverse fault (TF) nanowires grow normal to the defect plane, while axial fault (AF) ones grow within the defect plane. (2) Understanding the growth mechanism of as-synthesized boron carbide nanowires. The growth mechanism can be generally considered as the famous vapor-liquid-solid (VLS) mechanism. TF and AF nanowires were found to be guided by Ni-B catalysts of two phases. A TF nanowire is lead by a hexagonal phase catalyst, which was proved to be in a liquid state during reaction. While an AF nanowires is catalyzed by a

  1. Oleylamine Assisted Synthesis of Ultralong Copper Nanowires

    Directory of Open Access Journals (Sweden)

    Tan Michael

    2015-01-01

    Full Text Available This paper reports the hydrothermal synthesis of smooth and ultralong copper nanowires (Cu NW prepared using oleylamine (OM, oleic acid (OA, and Cl- ion as coordinating and etching agents respectively. Cu nanowires with mean diameters around 82.3 nm and lengths exceeding 300 μm were synthesized using 2 % vol. OM and 1.8 mM OA at 120ºC after 12 h. The Cu NWs exhibit five-fold twinning and growth along the [110] direction. The morphological evolution of the products were also observed and discussed. Without Cl-, octahedral crystals instead of nanowires were formed. The addition of oleic acid as coordinating agent resulted to fewer particles and smoother nanowires which exhibit excellent mechanical stability. This method provides a simple, low-cost and high yield synthesis of Cu NWs for applications such as gas sensors and transparent conducting electrodes.

  2. Characterizing the elasticity of hollow metal nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Ji Changjiang; Park, Harold S [Department of Civil and Environmental Engineering, Vanderbilt University, Nashville, TN 37235 (United States)

    2007-03-21

    We have performed atomistic simulations on solid and hollow copper nanowires to quantify the elastic properties of hollow nanowires (nanoboxes). We analyse variations in the modulus, yield stress and strain for <100> and <110> nanoboxes by varying the amount of bulk material that is removed to create the nanoboxes. We find that, while <100> nanoboxes show no improvement in elastic properties as compared to solid <100>nanowires, <110> nanoboxes can show enhanced elastic properties as compared to solid <110> nanowires. The simulations reveal that the elastic properties of the nanoboxes are strongly dependent on the relative strength of the bulk material that has been removed, as well as the total surface area of the nanoboxes, and indicate the potential of ultralight, high-strength nanomaterials such as nanoboxes.

  3. Nanowire-based All Oxide Solar Cells

    OpenAIRE

    Yang, Peidong

    2009-01-01

    We present an all-oxide solar cell fabricated from vertically oriented zinc oxide nanowires and cuprous oxide nanoparticles. Our solar cell consists of vertically oriented n-type zinc oxide nanowires, surrounded by a film constructed from p-type cuprous oxide nanoparticles. Our solution-based synthesis of inexpensive and environmentally benign oxide materials in a solar cell would allow for the facile production of large-scale photovoltaic devices. We found that the solar cell performance is ...

  4. Dimensional crossover of thermal conductance in nanowires

    OpenAIRE

    Jian WANG; Wang, Jian-Sheng

    2007-01-01

    Dimensional dependence of thermal conductance at low temperatures in nanowires is studied using the nonequilibrium Green's function (NEGF) method. Our calculation shows a smooth dimensional crossover of thermal conductance in nanowire from one-dimensional to three-dimensional behavior with the increase of diameters. The results are consistent with the experimental findings that the temperature dependence of thermal conductance at low temperature for diameters from tens to hundreds nanometers ...

  5. Nanowires and nanostructures fabrication using template methods

    DEFF Research Database (Denmark)

    Mátéfi-Tempfli, Stefan; Mátéfi-Tempfli, M.; Vlad, A.;

    2009-01-01

    One of the great challenges of today is to find reliable techniques for the fabrication of nanomaterials and nanostructures. Methods based on template synthesis and on self organization are the most promising due to their easiness and low cost. This paper focuses on the electrochemical synthesis ...... nanowires and nanostructures using nanoporous host materials such as supported anodic aluminum considering it as a key template for nanowires based devices. New ways are opened for applications by combining such template synthesis methods with nanolithographic techniques....

  6. Growth and characterization of bismuth telluride nanowires

    International Nuclear Information System (INIS)

    Polycrystalline Bi2Te3 nanowires are electrochemically grown in ion track-etched polycarbonate membranes. Potentiostatic growth is demonstrated in templates of various thicknesses ranging from 10 to 100 μm. The smallest observed nanowire diameters are 20 nm in thin membranes and approx. 140-180 nm in thicker membranes. The influence of the various deposition parameters on the nanowire growth rate is presented. Slower growth rates are attained by selective change of deposition potentials and lower temperatures. Nanowires synthesized at slower growth rates have shown to possess a higher degree of crystalline order and smoother surface contours. With respect to structural properties, X-ray diffraction and transmission electron microscopy verified the growth of Bi2Te3 and evidenced the stability of specific properties, e.g. grain size or preferential orientation, with regard to variations in the deposition conditions. The interdependency of the fabrication parameters, i.e. temperature, deposition potential and nanochannel diameters, is demonstrated for wires grown in 30 μm thick membranes. It is visible from diffraction analysis that texture is tunable by the growth conditions but depends also on the size of the nanochannels in the template. Both (015) and (110) reflexes are observed for the nanowire arrays. Energy dispersive X-ray analysis further points out that variation of nanochannel size could lead to a change in elemental composition of the nanowires. (orig.)

  7. Growth and characterization of bismuth telluride nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Picht, Oliver

    2010-05-26

    Polycrystalline Bi{sub 2}Te{sub 3} nanowires are electrochemically grown in ion track-etched polycarbonate membranes. Potentiostatic growth is demonstrated in templates of various thicknesses ranging from 10 to 100 {mu}m. The smallest observed nanowire diameters are 20 nm in thin membranes and approx. 140-180 nm in thicker membranes. The influence of the various deposition parameters on the nanowire growth rate is presented. Slower growth rates are attained by selective change of deposition potentials and lower temperatures. Nanowires synthesized at slower growth rates have shown to possess a higher degree of crystalline order and smoother surface contours. With respect to structural properties, X-ray diffraction and transmission electron microscopy verified the growth of Bi{sub 2}Te{sub 3} and evidenced the stability of specific properties, e.g. grain size or preferential orientation, with regard to variations in the deposition conditions. The interdependency of the fabrication parameters, i.e. temperature, deposition potential and nanochannel diameters, is demonstrated for wires grown in 30 {mu}m thick membranes. It is visible from diffraction analysis that texture is tunable by the growth conditions but depends also on the size of the nanochannels in the template. Both (015) and (110) reflexes are observed for the nanowire arrays. Energy dispersive X-ray analysis further points out that variation of nanochannel size could lead to a change in elemental composition of the nanowires. (orig.)

  8. Synthesis of Nanowires by Spray Pyrolysis

    Directory of Open Access Journals (Sweden)

    Kalyana C. Pingali

    2009-01-01

    Full Text Available Nanowires of carbon as well as nickel-carbon (Ni-C were synthesized by spray-pyrolysis. The carbon nanowires were synthesized using methanol as a precursor while the Ni-C nanowires were obtained by using nickel chloride methanol solution as feed. It was found that low argon carrier gas flow rates (<100 cm3/min and suitable reaction temperatures (∼700∘C were found to be critical for the formation of wired structures. The formation of nanowires was quite sensitive to reaction temperature. Nanowires could not form at temperatures higher than 900∘C in the presence of hexane. Ruthenium chloride and nickel chloride dissolved in hexane and methanol resulted in carbon coated binary metallic nanoparticles. Morphological differences of carbon nanowires, Ni-C wires and carbon coated binary nanoparticles were characterized by scanning electron microscopy (SEM and energy-dispersive X-ray analysis (EDS. The formation mechanism for the wired structures is proposed to explain the structural results obtained.

  9. Why self-catalyzed nanowires are most suitable for large-scale hierarchical integrated designs of nanowire nanoelectronics

    Science.gov (United States)

    Noor Mohammad, S.

    2011-10-01

    Nanowires are grown by a variety of mechanisms, including vapor-liquid-solid, vapor-quasiliquid-solid or vapor-quasisolid-solid, oxide-assisted growth, and self-catalytic growth (SCG) mechanisms. A critical analysis of the suitability of self-catalyzed nanowires, as compared to other nanowires, for next-generation technology development has been carried out. Basic causes of superiority of self-catalyzed (SCG) nanowires over other nanowires have been described. Polytypism in nanowires has been studied, and a model for polytypism has been proposed. The model predicts polytypism in good agreement with available experiments. This model, together with various evidences, demonstrates lower defects, dislocations, and stacking faults in SCG nanowires, as compared to those in other nanowires. Calculations of carrier mobility due to dislocation scattering, ionized impurity scattering, and acoustic phonon scattering explain the impact of defects, dislocations, and stacking faults on carrier transports in SCG and other nanowires. Analyses of growth mechanisms for nanowire growth directions indicate SCG nanowires to exhibit the most controlled growth directions. In-depth investigation uncovers the fundamental physics underlying the control of growth direction by the SCG mechanism. Self-organization of nanowires in large hierarchical arrays is crucial for ultra large-scale integration (ULSI). Unique features and advantages of self-organized SCG nanowires, unlike other nanowires, for this ULSI have been discussed. Investigations of nanowire dimension indicate self-catalyzed nanowires to have better control of dimension, higher stability, and higher probability, even for thinner structures. Theoretical calculations show that self-catalyzed nanowires, unlike catalyst-mediated nanowires, can have higher growth rate and lower growth temperature. Nanowire and nanotube characteristics have been found also to dictate the performance of nanoelectromechanical systems. Defects, such as

  10. Phase transformation in free-standing SMA nanowires

    International Nuclear Information System (INIS)

    The primary focus of this work is on determining if the phase transformation of shape memory alloy (SMA) nanowires exhibits a critical size below which the phase transformation is inhibited. The SMA nanowires are fabricated through the use of the mechanical pressure injection method. The mechanical pressure injection method is a template-assisted nanowire fabrication method in which an anodized aluminum oxide (AAO) template is impregnated with liquid metal. The fabrication of SMA nanowires with different diameters is accomplished through the fabrication of AAO templates of varying diameters. The phase transformation behavior of the fabricated SMA nanowires is characterized using transmission electron microscopy. By analysis of the fabricated SMA nanowires, it is found that the phase transformation of SMA nanowires is not affected for nanowires ranging in diameter from 650 to 10 nm.

  11. Nanoscale manipulation of Ge nanowires by ion hammering

    Energy Technology Data Exchange (ETDEWEB)

    Picraux, Samuel T [Los Alamos National Laboratory; Romano, Lucia [UNIV OF FLORIDA; Rudawski, Nicholas G [UNIV OF FLORIDA; Holzworth, Monta R [UNIV OF FLORIDA; Jones, Kevin S [UNIV OF FLORIDA; Choi, S G [NREL

    2009-01-01

    Nanowires generated considerable interest as nanoscale interconnects and as active components of both electronic and electromechanical devices. However, in many cases, manipulation and modification of nanowires are required to realize their full potential. It is essential, for instance, to control the orientation and positioning of nanowires in some specific applications. This work demonstrates a simple method to reversibly control the shape and the orientation of Ge nanowires by using ion beams. Initially, crystalline nanowires were partially amorphized by 30 keY Ga+-implantation. After amorphization, viscous flow and plastic deformation occurred due to the ion hammering effect, causing the nanowires to bend toward the beam direction. The bending was reversed multiple times by ion-implanting the opposite side of the nanowires, resulting in straightening of the nanowires and subsequent bending in the opposite direction. This ion hammering effect demonstrates the detailed manipulation of nanoscale structures is possible through the use of ion irradiation.

  12. Resistance Fluctuations in GaAs Nanowire Grids

    Directory of Open Access Journals (Sweden)

    Ivan Marasović

    2014-01-01

    Full Text Available We present a numerical study on resistance fluctuations in a series of nanowire-based grids. Each grid is made of GaAs nanowires arranged in parallel with metallic contacts crossing all nanowires perpendicularly. Electrical properties of GaAs nanowires known from previous experimental research are used as input parameters in the simulation procedure. Due to the nonhomogeneous doping, the resistivity changes along nanowire. Allowing two possible nanowire orientations (“upwards” or “downwards”, the resulting grid is partially disordered in vertical direction which causes resistance fluctuations. The system is modeled using a two-dimensional random resistor network. Transfer-matrix computation algorithm is used to calculate the total network resistance. It is found that probability density function (PDF of resistance fluctuations for a series of nanowire grids changes from Gaussian behavior towards the Bramwell-Holdsworth-Pinton distribution when both nanowire orientations are equally represented in the grid.

  13. Thermal stability of silicon nanowires:atomistic simulation study

    Institute of Scientific and Technical Information of China (English)

    Liu Wen-Liang; Zhang Kai-Wang; Zhong Jian-Xin

    2009-01-01

    Using the Stillinger-Weber (SW) potential model, we investigate the thermal stability of pristine silicon nanowires based on classical molecular dynamics (MD) simulations. We explore the structural evolutions and the Lindemann indices of silicon nanowires at different temperatures in order to unveil atomic-level melting behaviour of silicon nanowires.The simulation results show that silicon nanowires with surface reconstructions have higher thermal stability than those without surface reconstructions, and that silicon nanowires with perpendicular dimmer rows on the two (100) surfaces have somewhat higher thermal stability than nanowires with parallel dimmer rows on the two (100) surfaces. Furthermore, the melting temperature of silicon nanowires increases as their diameter increases and reaches a saturation value close to the melting temperature of bulk silicon. The value of the Lindemann index for melting silicon nanowires is 0.037.

  14. Fabrication of rhenium nanowires by selective etching of eutectic alloys

    International Nuclear Information System (INIS)

    Rhenium nanowires have been fabricated via directional solidification and selective etching of a eutectic alloy. A NiAl-1.5 at.%Re eutectic alloy was directionally solidified using a constant growth rate and temperature gradient, in the Bridgman-type directional solidification furnace. The selective dissolution of the NiAl matrix was achieved with a mixture of HCl:H2O2, and produced an anisotropic etching of the eutectic, with the favoured etching directions aligned in parallel. The corroded surface was dominated by long rhenium fibres (diameter ∼400 nm), although shorter, and sometimes more rectangular wires were also observed in some sections. Digestion of the NiAl-Re eutectic in sulphuric acid, on the other hand, produced mainly long rhenium fibres of consistent shape and length. Both etching procedures might subsequently be applied for the preparation of nanodisc electrode arrays by embedding the obtained Re nanowires into a polymer and grinding until the wires are exposed. The reduction on the electrode area inherent in the use of such nanoelectrodes would allow a considerable increase in the signal-to-noise ratio, thus favouring the system for its application in analytical sensors. The use of rhenium in the electrode formation might also favour its application in high-temperature measurements

  15. Dependence of magnetization process in a Ni-Fe nanowire on the width of the nanowire

    Energy Technology Data Exchange (ETDEWEB)

    Endo, Y; Matsumura, Y; Nakatani, R; Yamamoto, M [Department of Materials Science and Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)], E-mail: endo@mat.eng.osaka-u.ac.jp

    2008-03-15

    We investigated the dependence of the magnetization process in 30-nm-thick Ni-Fe nanowires on the width of the nanowire using the magnetic field sweeping (MFS) - magnetic force microscopy (MFM), which measures phase changes (stray field changes) using a MFM tip as a detector. The phase changes are dependent on the width of the nanowire; hysteresis loops of the phase and plateau areas of the phase are observed at local points for the widths between 100 - 600 nm, while local points, each, display the hysteresis loops of the phase and the valleys of the phase for the width of 800 nm. These results demonstrate that the dominant factor in the magnetization process of 30-nm-thick Ni-Fe nanowires changes from 'domain wall motion and domain wall pinning' to 'domain wall motion with increasing the width of the nanowires'.

  16. 红茶菌产细菌纤维素菌种分离与初步鉴定%Isolation and Identification of Microbes from Kombucha Producing Bacterial Cellulose

    Institute of Scientific and Technical Information of China (English)

    张妍; 徐伟; 傅徐阳

    2012-01-01

    Traditional kombucha will form a layer of white membrane in green tea-sucrose medium surface. Microbes attached to the membrane were taken. The A and Y strains were isolated by crossing on the acetic acid bacterial and yeast plate medium. The two strains were isolated and identified Gluconobacter asai and Schizosaccharomyces pombeLinder by observing the colonies & cell morphology and physiological & biochemical tests separately. The mixture of the two strains was inoculated in green tea-sucrose medium and the products were identified as bacterial cellulose.%传统红茶菌在绿茶-蔗糖培养基表面会形成一层白色菌膜,取附着于菌膜上的菌体,在醋酸菌和酵母菌平板培养基上划线分离得到纯菌种A和Y,经菌落、菌体形态观察和生理生化试验鉴定,确定A为葡糖杆菌Gluconobacter asai和Y为路德类酵母Saccharomycodes ludwigli,进一步将两种菌株混合接入绿茶-蔗糖培养液中,对产物判定结果为纤维素。

  17. Synthesis and characterization of Co2FeAl nanowires

    Science.gov (United States)

    Sapkota, Keshab R.; Gyawali, Parshu; Forbes, Andrew; Pegg, Ian L.; Philip, John

    2012-06-01

    We report the growth and characterization of Co2FeAl nanowires. Nanowires are grown using electrospinning method and the diameters range from 50 to 500 nm. These nanowires exhibit cubic crystal structure with a lattice constant of a =5.639 Å. The nanowires exhibit ferromagnetic behavior with a very high Curie temperature. The temperature dependent magnetization behavior displays an anomaly in the temperature range 600-850 K, which disappears at higher external magnetic fields.

  18. Superconducting properties of lead nanowires fabricated by electrochemical deposition

    Science.gov (United States)

    Ishii, S.; Sadki, E. S.; Ooi, S.; Ochiai, Y.; Hirata, K.

    2005-10-01

    Pb nanowires were fabricated by electrochemical deposition inside the nanopores of polycarbonate membranes. The diameter of fabricated nanowires ranged from 80 to 100 nm, and length is 5 μm on average. Temperature dependence of resistance was measured in magnetic fields by two-point contact method. It is found that the nanowires show a broad transition with higher critical fields compared with typical values of bulk Pb, and that the nanowires belong to Type II superconductors.

  19. Superconducting properties of lead nanowires fabricated by electrochemical deposition

    International Nuclear Information System (INIS)

    Pb nanowires were fabricated by electrochemical deposition inside the nanopores of polycarbonate membranes. The diameter of fabricated nanowires ranged from 80 to 100 nm, and length is 5 μm on average. Temperature dependence of resistance was measured in magnetic fields by two-point contact method. It is found that the nanowires show a broad transition with higher critical fields compared with typical values of bulk Pb, and that the nanowires belong to Type II superconductors

  20. Electrochemical Fabrication of Metallic Nanowires and Metal Oxide Nanopores

    OpenAIRE

    Ohgai, Takeshi; Mizumoto, Masayuki; Nomura, Shigeki; Kagawa, Akio

    2007-01-01

    A nuclear track etched polycarbonate membrane filter with numerous cylindrical nanopores was applied as a nanoporous template for growing metallic nanowires. Nickel, cobalt, and iron nanowires were electrodeposited into the cylindrical nanopores. Cathodic polarization curves were measured to determine an optimum condition for growing nanowires. The shape of nanowires was observed using scanning electron microscope (SEM) and the crystal structure was analyzed using transmission electron micros...

  1. Synthesis and characterization of single crystalline selenium nanowire arrays

    International Nuclear Information System (INIS)

    Ordered selenium nanowire arrays with diameters about 40 nm have been fabricated by electrodeposition using anodic porous alumina templates. As determined by X-ray diffraction, Raman spectra, electron diffraction and high-resolution transmission electron microscopy, selenium nanowires have uniform diameters, which are fully controllable. Single crystalline trigonal selenium nanowires have been obtained after postannealing at 180 deg. C. These nanowires are perfect with a c-axis growth orientation. The optical absorption spectra reveal two types of electron transition activity

  2. Long-range magnetostatic interactions in arrays of nanowires

    CERN Document Server

    Raposo, V; González, J M; Vázquez, M

    2000-01-01

    Experimental measurements and micromagnetic simulations of the hysteresis loops of arrays of cobalt nanowires are compared here. Arrays of cobalt nanowires (200 nm in diameter) were electrodeposited into the pores of alumina membranes (thickness 60 mu m). Their hysteresis loops along the axial direction of nanowires were measured using vibrating sample magnetometry. Micromagnetic simulations were performed considering dipolar interaction between nanowires leading to similar hysteresis loops as those obtained experimentally.

  3. Epitaxial growth of aligned GaN nanowires and nanobridges

    OpenAIRE

    Kim, Kyungkon; Henry, Tania; Cui, George; Han, Jung; Song, Yoon-Kyu; Nurmikko, Arto V.; Tang, Hong

    2007-01-01

    Homo-epitaxialy grown aligned GaN nanowires were prepared on crystalline GaN mesas. The GaN nanowires showed preferential growth along the 〈100〉 direction (m-axis direction). By using selectively positioned and crystallographically well defined GaN epitaxial lateral overgrowth (ELO) mesas as substrate, we obtained horizontally aligned GaN nanowires, in comb-like arrays and hexagonal network interconnecting the ELO mesas. Preliminary testing of the nanomechanical behavior of horizontal nanowir...

  4. Manganese oxide nanowires, films, and membranes and methods of making

    Science.gov (United States)

    Suib, Steven Lawrence; Yuan, Jikang

    2011-02-15

    Nanowires, films, and membranes comprising ordered porous manganese oxide-based octahedral molecular sieves and methods of making the same are disclosed. A method for forming nanowires includes hydrothermally treating a chemical precursor composition in a hydrothermal treating solvent to form the nanowires, wherein the chemical precursor composition comprises a source of manganese cations and a source of counter cations, and wherein the nanowires comprise ordered porous manganese oxide-based octahedral molecular sieves.

  5. Controlled growth of single nanowires within a supported alumina template

    DEFF Research Database (Denmark)

    Vlad, A.; Mátéfi-Tempfli, M.; Faniel, S.;

    2006-01-01

    A simple technique for fabricating single nanowires with well-defined position is presented. The process implies the use of a silicon nitride mask for selective electrochemical growth of the nanowires in a porous alumina template. We show that this method allows the realization of complex nanowire...... patterns as well as arrays of single nanowires with a precise position and spacing. © IOP Publishing Ltd....

  6. Blue Luminescence of CdS Nanowires Synthesized by Sulfurization

    Institute of Scientific and Technical Information of China (English)

    GAO Tao; MENG Guo-Wen; WANG Tai-Hong

    2004-01-01

    @@ Polycrystalline CdS nanowires have been synthesized by sulfurizing metal Cd nanowires deposited electrochemically within the nanochannels of porous anodic alumina (PAA) templates. Photoluminescence (PL) investigation shows that the CdS nanowires have an intensive and broad PL emission band peaked around 435nm. The investigation results suggest that localized defects and excess S atoms existing in the CdS nanowires are responsible for this blue luminescence.

  7. Fabrication of nanowires by varying energy microbeam lithography using heavy ions at the TIARA

    Energy Technology Data Exchange (ETDEWEB)

    Kamiya, T. [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency (JAEA), 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan)], E-mail: kamiya.tomihiro@jaea.go.jp; Takano, K.; Ishii, Y.; Satoh, T.; Oikawa, M.; Ohkubo, T.; Haga, J. [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency (JAEA), 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan); Nishikawa, H.; Furuta, Y.; Uchiya, N. [Dept. of Electrical Engineering, Shibaura Institute of Technology, 3-7-5 Toyosu, Koto-ku, Tokyo 135-8548 (Japan); Seki, S. [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Sugimoto, M. [Quatum Beam Science Directorate, Japan Atomic Energy Agency (JAEA), 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan)

    2009-06-15

    In TIARA facility of Japan Atomic Energy Agency (JAEA) Takasaki, we have produced three-dimensional micro/nano-structures with high aspect ratio using cross linking process based on negative resist such as SU-8 by a technique of mask less ion beam lithography. By bombarding high energy heavy ions such as 450 MeV Xe{sup 23+} to SU-8, on the other hand, it appeared that a nanowire could be produced just with a single ion hitting. Then we tried to produce nanowires, of which both ends were fixed in the three-dimensional structure. This paper shows a preliminary experiment for this purpose using a combination of 15 MeV Ni{sup 4+} ion microbeam patterning and the 450 MeV {sup 129}Xe{sup 23+} hitting on SU-8.

  8. Photonic nanowires for quantum optics

    DEFF Research Database (Denmark)

    Munsch, M.; Claudon, J.; Bleuse, J.;

    Photonic nanowires (PWs) are simple dielectric structures for which a very efficient and broadband spontaneous emission (SE) control has been predicted [1]. Recently, a single photon source featuring a record high efficiency was demonstrated using this geometry [2]. Using time-resolved micro......-photoluminescence, we investigate directly the SE of single InAs quantum dots (QDs) embedded in GaAs PWs and demonstrate performances that fully confirm the theoretical predictions [3]. In addition, we discuss recent results obtained on elliptical wires that ensure an efficient control of the photon polarization [4......, equivalent to the one obtained in state-of-the-art 2D photonic crystals, is measured. Moreover, a PW featuring an elliptical section provides a very efficient control over the polarization of the emitted photon. In that case, only one guided mode, with a linear polarization oriented along the major axis, is...

  9. Controlled Living Nanowire Growth: Precise Control over the Morphology and Optical Properties of AgAuAg Bimetallic Nanowires.

    Science.gov (United States)

    Mayer, Martin; Scarabelli, Leonardo; March, Katia; Altantzis, Thomas; Tebbe, Moritz; Kociak, Mathieu; Bals, Sara; García de Abajo, F Javier; Fery, Andreas; Liz-Marzán, Luis M

    2015-08-12

    Inspired by the concept of living polymerization reaction, we are able to produce silver-gold-silver nanowires with a precise control over their total length and plasmonic properties by establishing a constant silver deposition rate on the tips of penta-twinned gold nanorods used as seed cores. Consequently, the length of the wires increases linearly in time. Starting with ∼210 nm × 32 nm gold cores, we produce nanowire lengths up to several microns in a highly controlled manner, with a small self-limited increase in thickness of ∼4 nm, corresponding to aspect ratios above 100, whereas the low polydispersity of the product allows us to detect up to nine distinguishable plasmonic resonances in a single colloidal solution. We analyze the spatial distribution and the nature of the plasmons by electron energy loss spectroscopy and obtain excellent agreement between measurements and electromagnetic simulations, clearly demonstrating that the presence of the gold core plays a marginal role, except for relatively short wires or high-energy modes. PMID:26134470

  10. Failure mechanisms and electromechanical coupling in semiconducting nanowires

    Directory of Open Access Journals (Sweden)

    Peng B.

    2010-06-01

    Full Text Available One dimensional nanostructures, like nanowires and nanotubes, are increasingly being researched for the development of next generation devices like logic gates, transistors, and solar cells. In particular, semiconducting nanowires with a nonsymmetric wurtzitic crystal structure, such as zinc oxide (ZnO and gallium nitride (GaN, have drawn immense research interests due to their electromechanical coupling. The designing of the future nanowire-based devices requires component-level characterization of individual nanowires. In this paper, we present a unique experimental set-up to characterize the mechanical and electromechanical behaviour of individual nanowires. Using this set-up and complementary atomistic simulations, mechanical properties of ZnO nanowires and electromechanical properties of GaN nanowires were investigated. In ZnO nanowires, elastic modulus was found to depend on nanowire diameter decreasing from 190 GPa to 140 GPa as the wire diameter increased from 5 nm to 80 nm. Inconsistent failure mechanisms were observed in ZnO nanowires. Experiments revealed a brittle fracture, whereas simulations using a pairwise potential predicted a phase transformation prior to failure. This inconsistency is addressed in detail from an experimental as well as computational perspective. Lastly, in addition to mechanical properties, preliminary results on the electromechanical properties of gallium nitride nanowires are also reported. Initial investigations reveal that the piezoresistive and piezoelectric behaviour of nanowires is different from bulk gallium nitride.

  11. Understanding quantum confinement in nanowires: basics, applications and possible laws

    International Nuclear Information System (INIS)

    A comprehensive investigation of quantum confinement in nanowires has been carried out. Though applied to silicon nanowires (SiNWs), it is general and applicable to all nanowires. Fundamentals and applications of quantum confinement in nanowires and possible laws obeyed by these nanowires, have been investigated. These laws may serve as backbones of nanowire science and technology. The relationship between energy band gap and nanowire diameter has been studied. This relationship appears to be universal. A thorough review indicates that the first principles results for quantum confinement vary widely. The possible cause of this variation has been examined. Surface passivation and surface reconstruction of nanowires have been elucidated. It has been found that quantum confinement owes its origin to surface strain resulting from surface passivation and surface reconstruction and hence thin nanowires may actually be crystalline-core/amorphous-shell (c-Si/a-Si) nanowires. Experimental data available in the literature corroborate with the suggestion. The study also reveals an intrinsic relationship between quantum confinement and the surface amorphicity of nanowires. It demonstrates that surface amorphicity may be an important tool to investigate the electronic, optoelectronic and sensorial properties of quantum-confined nanowires. (topical review)

  12. Potential of semiconductor nanowires for single photon sources

    NARCIS (Netherlands)

    Harmand, J.-C.; Liu, L.; Patriarche, G.; Tchernycheva, M.; Akopian, N.; Perinetti, U.; Zwiller, V.

    2009-01-01

    The catalyst-assisted growth of semiconductor nanowires heterostructures offers a very flexible way to design and fabricate single photon emitters. The nanowires can be positioned by organizing the catalyst prior to growth. Single quantum dots can be formed in the core of single nanowires which can

  13. Quantification of nanowire uptake by live cells

    KAUST Repository

    Margineanu, Michael B.

    2015-05-01

    Nanostructures fabricated by different methods have become increasingly important for various applications at the cellular level. In order to understand how these nanostructures “behave” and for studying their internalization kinetics, several attempts have been made at tagging and investigating their interaction with living cells. In this study, magnetic iron nanowires with an iron oxide layer are coated with (3-Aminopropyl)triethoxysilane (APTES), and subsequently labeled with a fluorogenic pH-dependent dye pHrodo™ Red, covalently bound to the aminosilane surface. Time-lapse live imaging of human colon carcinoma HCT 116 cells interacting with the labeled iron nanowires is performed for 24 hours. As the pHrodo™ Red conjugated nanowires are non-fluorescent outside the cells but fluoresce brightly inside, internalized nanowires are distinguished from non-internalized ones and their behavior inside the cells can be tracked for the respective time length. A machine learning-based computational framework dedicated to automatic analysis of live cell imaging data, Cell Cognition, is adapted and used to classify cells with internalized and non-internalized nanowires and subsequently determine the uptake percentage by cells at different time points. An uptake of 85 % by HCT 116 cells is observed after 24 hours incubation at NW-to-cell ratios of 200. While the approach of using pHrodo™ Red for internalization studies is not novel in the literature, this study reports for the first time the utilization of a machine-learning based time-resolved automatic analysis pipeline for quantification of nanowire uptake by cells. This pipeline has also been used for comparison studies with nickel nanowires coated with APTES and labeled with pHrodo™ Red, and another cell line derived from the cervix carcinoma, HeLa. It has thus the potential to be used for studying the interaction of different types of nanostructures with potentially any live cell types.

  14. Synthesis and Characterization of ZnO Nanowires

    Institute of Scientific and Technical Information of China (English)

    Huang Michael Hsuan-Yi; Mao Samuel; Henning Feick; Yan Haoquan; Wu Yiying; Hennes Kind; Richard Russo; Eicke Weber; Yang Peidong

    2004-01-01

    Zinc oxide is a wide bandgap (3.37 eV) semiconductor with a hexagonal wurtzite crystal structure. ZnO prepared in nanowire form may be used as a nanosized ultraviolet light-emitting source. In this study, ZnO nanowires were prepared by vapor-phase transport of Zn vapor onto gold-coated silicon substrates in a tube furnace heated to 900 C. Gold serves as a catalyst to capture Zn vapor during nanowire growth.Size control of ZnO nanowires has been achieved by varying the gold film thickness, using fine gold clusters, or tuning other growth conditions. Nanowire diameters ranging from 20 - 200 nm and lengths between 2 - 40 μm can be made. Structural characterization of the nanowires was mainly performed using powder X-ray diffractometry, scanning and transmission electron microscopy. Orientational control of ZnO nanowires can be achieved by growing the nanowires on sapphire substrates. Nearly perfect lattice match between the (002) c-axis growth of ZnO nanowires and the (110) a-plane surface of sapphire substrate allows vertical growth of ZnO nanowires. Fabrication of patterned ZnO nanowire array was then made by patterning the gold layer on the sapphire substrates.Optical characterization of the ZnO nanowires using a He-Cd laser (325 nm) shows that the nanowires possess a strong emission band around 375 - 380 nm. Room temperature power-dependent photoluminescence study using a Nd:YAG laser (266 nm, 3-ns pulse width) shows that the nanowires exhibit lasing emission property. This is the first nanowire system displaying such phenomenon.

  15. Fluorescence spectroscopy of electrochemically self-assembled ZnSe and Mn:ZnSe nanowires

    International Nuclear Information System (INIS)

    We report room temperature fluorescence spectroscopy (FL) studies of ZnSe and Mn-doped ZnSe nanowires of different diameters (10, 25, 50 nm) produced by an electrochemical self-assembly technique. All samples exhibit increasing blue-shift in the band edge fluorescence with decreasing wire diameter because of quantum confinement. The 10 nm ZnSe nanowires show four distinct emission peaks due to band-to-band recombination, exciton recombination, recombination via surface states and via band gap (trap) states. The exciton binding energy in these nanowires exhibits a giant increase (∼10-fold) over the bulk value due to quantum confinement, since the effective wire radius (taking into account side depletion) is smaller than the exciton Bohr radius in bulk ZnSe. The 25 and 50 nm diameter wires show only a single FL peak due to band-to-band electron-hole recombination. In the case of Mn-doped ZnSe nanowires, the band edge luminescence in 10 nm samples is significantly quenched by Mn doping but not the exciton luminescence, which remains relatively unaffected. We observe additional features due to Mn2+ ions. The spectra also reveal that the emission from Mn2+ states increases in intensity and is progressively red-shifted with increasing Mn concentration

  16. Fabrication and optical properties of multishell InAs quantum dots on GaAs nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Xin; Zhang, Xia, E-mail: xzhang@bupt.edu.cn; Li, Junshuai; Cui, Jiangong; Ren, Xiaomin [State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876 (China)

    2015-02-07

    Hybrid nanostructures combining nanowires with quantum dots promote the development of nanoelectronic and nanophotonic devices with integrated functionalities. In this work, we present a complex nanostructure with multishell quantum dots grown on nanowires. 1–4 shells of Stranski-Krastanov InAs quantum dots are grown on the sidewalls of GaAs nanowires by metal organic chemical vapor deposition. Different dot shells are separated by 8 nm GaAs spacer shells. With increasing the number of shells, the quantum dots become sparser and tend to align in one array, which is caused by the shrinkage of facets on which dots prefer to grow as well as the strain fields produced by the lower set of dots which influences the migration of In adatoms. The size of quantum dots increases with the increase of shell number due to enhanced strain fields coupling. The spectra of multishell dots exhibit multiwavelength emission, and each peak corresponds to a dot shell. This hybrid structure may serve as a promising element in nanowire intermediate band solar cells, infrared nanolasers, and photodetectors.

  17. Fabrication and optical properties of multishell InAs quantum dots on GaAs nanowires

    International Nuclear Information System (INIS)

    Hybrid nanostructures combining nanowires with quantum dots promote the development of nanoelectronic and nanophotonic devices with integrated functionalities. In this work, we present a complex nanostructure with multishell quantum dots grown on nanowires. 1–4 shells of Stranski-Krastanov InAs quantum dots are grown on the sidewalls of GaAs nanowires by metal organic chemical vapor deposition. Different dot shells are separated by 8 nm GaAs spacer shells. With increasing the number of shells, the quantum dots become sparser and tend to align in one array, which is caused by the shrinkage of facets on which dots prefer to grow as well as the strain fields produced by the lower set of dots which influences the migration of In adatoms. The size of quantum dots increases with the increase of shell number due to enhanced strain fields coupling. The spectra of multishell dots exhibit multiwavelength emission, and each peak corresponds to a dot shell. This hybrid structure may serve as a promising element in nanowire intermediate band solar cells, infrared nanolasers, and photodetectors

  18. Silicon nanowire properties from theory and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Scheel, H.M.

    2007-09-10

    Silicon has played an outstanding role at the end of the 20th century and is still one of the most important components for micro computing. In recent years the ability to miniaturize semiconductor structures and devices to nanometer length scales has opened an all new field of physics, i.e. nanoscience. Simply by miniaturizing the size of semiconducting structures the physics describing electronic or vibronic properties has to be altered fundamentally leading to new phenomena and interesting effects. For silicon the two major mile-stones where the fabrication of porous silicon and later the fabrication of free-standing silicon nanowires. The intense research concerning the fabrication of silicon nanowires has led to single crystalline nanowires with diameters of only a few nanometers. The hope that drove these intense research efforts where to find efficient photonic properties in these quantized systems. In the first part of this work detailed theoretical investigations are presented for the commonly observed ([111] and [11 anti 2]) representatives of free-standing and for the most frequently discussed ([001]) silicon nanowires not (so far) observed as free standing wires. Using density functional theory in the local density approximation the electronic properties as well as the structural changes due to the reduced dimensionality of silicon nanowires are calculated and discussed. The comparison to recent experimental, scanning tunneling experiments reveal a fundamental discrepancy between the calculated band structures and experimental findings. With our results we are able to explain these differences. Raman investigations on silicon nanowires where in a state of controversial discussion about the origin of observed red shifted spectra. Various contributions like quantum confinement, photo excitation and thermal effects where discussed. The second part of this thesis contributes to this discussion, with detailed laser power dependent Raman spectroscopic

  19. Raman study of thermochromic phase transition in tungsten trioxide nanowires

    Science.gov (United States)

    Lu, Dong Yu; Chen, Jian; Chen, Huan Jun; Gong, Li; Deng, Shao Zhi; Xu, Ning Sheng; Liu, Yu Long

    2007-01-01

    Tungsten trioxide (WO3) nanowires were synthesized by thermal evaporation of tungsten powder in two steps: tungsten suboxide (WO3-x) nanowires were synthesized, and then oxidized in O2 ambient and transformed into WO3 nanowires. Raman spectroscopy was applied to study the thermochromic phase transition of one-dimensional WO3 nanowires. From the temperature dependence of the characteristic mode at 33cm-1 in WO3, the phase transition temperature was determined. It was found that the phase transition of WO3 nanowires was reversible and the phase transition temperatures were even lower than that of WO3 nanopowder.

  20. Diameter Modification of Si Nanowires via Catalyst Size

    Institute of Scientific and Technical Information of China (English)

    邢英杰; 奚中和; 薛增泉; 俞大鹏

    2003-01-01

    Si nanowires with different diameters are grown on catalyst coated Si substrates via a solid-liquid-solid mechanism. It is found that the thickness and type of catalyst film can modify the average diameter of Si nanowires obviously. The nanowires prepared on substrates deposited with Ni film of 40, 10, and 4nm thick have a mean diameter around 41, 36, and 24nm, respectively. Si nanowires with the smallest average diameter (~ 16 nm) are grown with a gold catalyst. Studies of diameter distributions show that the minimum diameter of nanowires does not shift with the average diameters spontaneously and has the same size of 10nm.

  1. Electronic and Elastic Properties of Helical Nickel Nanowires

    Institute of Scientific and Technical Information of China (English)

    WANG Bao-Lin; ZHAO Ji-Jun; SHI Da-Ning; JIA Jian-Min; WANG Guang-Hou

    2005-01-01

    @@ The structural and elastic properties of ultrathin nickel nanovires are investigated by using molecular dynamics simulation with a Sutton-Chen potential. Helical multi-shell structures are obtained as the most stable structures for Ni nanowires with diameters of about 1 nm. The electronic states of these nanowires are computed and compared with that of Ni solid. The mechanical responses of the helical nanowires under tensile forces are simulated. We observe elastic deformation of nanowires characterized by periodic oscillations of the nanowire length under constant force. Within an elastic limit, both the atomic structures and the electronic structures remain stable under external tensile loading.

  2. Waveguiding properties and applications of silica nanowires in various environments

    Institute of Scientific and Technical Information of China (English)

    SUI Cheng-hua; WU Ping-hui; ZHAO Pan

    2009-01-01

    Waveguiding properties of silica nanowires in various environments are studied by solving the eigenvalue equations of a circular cross-section waveguide numerically in cylindrical coordinates. The single-mode condition, propagation constants, poynting vector and power distribution inside and outside silica nanowire are calculated. The results show that silica nanowires in water, compared with silica nanowires in air, have higher fraction of the evanescent fields. Due to the sensiti-vity to surrounding environment, silica nanowires are very suitable for sensing elements, which can be used to implement a single-mode fiber optic evanescent wave sensing element of highly sensitive and accurate measurement.

  3. Nanowire Electrodes for Advanced Lithium Batteries

    Directory of Open Access Journals (Sweden)

    Lei eHuang

    2014-10-01

    Full Text Available Since the commercialization of lithium ion batteries (LIBs in the past two decades, rechargeable LIBs have become widespread power sources for portable devices used in daily life. However, current demands require higher energy density and power density of batteries. The electrochemical energy storage performance of LIBs could be improved by applying nanomaterial electrodes, but their fast capacity fading is still one of the key limitations and the mechanism needs to be clearly understood. Single nanowire electrode devices are considered as a versatile platform for in situ probing the direct relationship between electrical transport, structure change, and other properties of the single nanowire electrode along with the charge/discharge process. The results indicate the conductivity decrease of the nanowire electrode and the structural disorder/destruction during electrochemical reactions which limit the cycling performance of LIBs. Based on the in situ observations, some feasible structure architecture strategies, including prelithiation, coaxial structure, nanowire arrays and hierarchical structure architecture, are proposed and utilized to restrain the conductivity decrease and structural disorder/destruction. Further, the applications of nanowire electrodes in some beyond Li-ion batteries, such as Li-S and Li-air battery, are also described.

  4. Nanomechanics of Single Crystalline Tungsten Nanowires

    Directory of Open Access Journals (Sweden)

    Volker Cimalla

    2008-01-01

    Full Text Available Single crystalline tungsten nanowires were prepared from directionally solidified NiAl-W alloys by a chemical release from the resulting binary phase material. Electron back scatter diffraction (EBSD proves that they are single crystals having identical crystallographic orientation. Mechanical investigations such as bending tests, lateral force measurements, and mechanical resonance measurements were performed on 100–300 nm diameter wires. The wires could be either directly employed using micro tweezers, as a singly clamped nanowire or in a doubly clamped nanobridge. The mechanical tests exhibit a surprisingly high flexibility for such a brittle material resulting from the small dimensions. Force displacement measurements on singly clamped W nanowires by an AFM measurement allowed the determination of a Young's modulus of 332 GPa very close to the bulk value of 355 GPa. Doubly clamped W nanowires were employed as resonant oscillating nanowires in a magnetomotively driven resonator running at 117 kHz. The Young's modulus determined from this setup was found to be higher 450 GPa which is likely to be an artefact resulting from the shift of the resonance frequency by an additional mass loading.

  5. Metallic nanowire growth from solution using dielectrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Nerowski, Alexander; Cuniberti, Gianaurelio [Institute for Materials Science, Max Bergmann Center of Biomaterials, Dresden University of Technology, 01069 Dresden (Germany); Poetschke, Markus; Bobeth, Manfred [Institute for Materials Science, Dresden University of Technology, 01069 Dresden (Germany); Weber, Walter [NamLab gGmbH, 01187 Dresden (Germany)

    2011-07-01

    A lot of effort has been made to manufacture metallic nanowires by top-down procedures as classical lithography. Metallic nanowire growth from solution represents a promising inexpensive bottom-up method working at room temperature. By applying an AC voltage, nanowires grow on a substrate between two electrodes in a solution containing metal complexes. Aiming at a controlled growth of straight and as thin as possible wires, the growth process is investigated both experimentally and theoretically. The nanowire itself, since it is conductive, is modeled as a half-sphere electrode. Our model includes the dielectrophoretic force on uncharged metal complexes as well as their diffusion in the solution. In particular, the growth velocity of the wire is found to depend only weakly on the applied voltage since the overall growth process is diffusion-controlled. Difficulties in comparing theoretical predictions and experimental observations due to poorly known material parameters are discussed. For reasonable parameter choices, the calculated nanowire growth velocity is in modest agreement with measurements.

  6. Metastable magnetic domain walls in cylindrical nanowires

    International Nuclear Information System (INIS)

    The stability of the asymmetric domain wall (ATDW) in soft magnetic cylindrical nanowires and nanotubes is investigated using micromagnetic simulations. Our calculated phase diagram shows that for cylindrical permalloy nanowires, the transverse domain wall (TDW) is the ground state for radii below 20 nm whilst the Bloch point wall (BPW) is favoured in thicker wires. The ATDW stabilises only as a metastable state but with energy close to that of the BPW. Characterisation of the DW spin structures reveals that the ATDW has a vortex-like surface spin state, in contrast to the divergent surface spins of the TDW. This results in lowering of surface charge above the critical radius. For both cylindrical nanotubes and nanowires we find that ATDWs only appear to exist as metastable static states and are particularly suppressed in nanotubes due to an increase in magnetostatic energy. - Highlights: • We simulate the micromagnetic structures of domain walls in cylindrical nanowires. • A phase diagram identifies ground and metastable states. • Asymmetric transverse walls are metastable in nanowires but suppressed in tubes. • Unrolling surface magnetisation aids visualisation of asymmetry and chirality. • We predict experimental discrimination based on magnetic charge distribution

  7. Identification and characterization of icosahedral metallic nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Pelaez, Samuel; Serena, Pedro A. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, c/Sor Juana Ines de la Cruz 3, Cantoblanco, 28049-Madrid (Spain); Guerrero, Carlo [Departamento de Fisica, Facultad Experimental de Ciencias, La Universidad del Zulia, Maracaibo (Venezuela); Paredes, Ricardo [Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas, Apto. 20632, Caracas 1020A (Venezuela); Garcia-Mochales, Pedro [Departamento de Fisica de la Materia Condensada, Facultad de Ciencias, Universidad Autonoma de Madrid, c/Tomas y Valiente 7, Cantoblanco, 28049-Madrid (Spain)

    2009-10-15

    We present and discuss an algorithm to identify ans characterize the long icosahedral structures (staggered pentagonal nanowires with 1-5-1-5 atomic structure) that appear in Molecular Dynamics simulations of metallic nanowires of different species subjected to stretching. The use of the algorithm allows the identification of pentagonal rings forming the icosahedral structure as well as the determination of its number n{sub p}, and the maximum length of the pentagonal nanowire L{sub p}{sup m}. The algorithm is tested with some ideal structures to show its ability to discriminate between pentagonal rings and other ring structures. We applied the algorithm to Ni nanowires with temperatures ranging between 4 K and 865 K, stretched along the[100] direction. We studied statistically the formation of pentagonal nanowires obtaining the distributions of length L{sub p}{sup m} and number of rings n{sub p} as function of the temperature. The L{sub p}{sup m} distribution presents a peaked shape, with peaks locate at fixes distances whose separation corresponds to the distance between two consecutive pentagonal rings. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Preparation and characterization of electrodeposited cobalt nanowires

    International Nuclear Information System (INIS)

    Electrochemical deposition technique has been used to deposit cobalt nanowires into the nano sized channels of Anodized Aluminium Oxide (AAO) templates. CoCl2Ðœ‡6H2O salt solution was used, which was buffered with H3BO3 and acidified by dilute H2SO4 to increase the plating life and control pH of the solution. Thin film of copper around 150 nm thick on one side of AAO template coated by e-beam evaporation system served as cathode to create electrical contact. FESEM analysis shows that the as-deposited nanowires are highly aligned, parallel to one another and have high aspect ratio with a reasonably high pore-filing factor. The TEM results show that electrodeposited cobalt nanowires are crystalline in nature. The Hysteresis loop shows the magnetization properties for in and out of plane configuration. The in plane saturation magnetization (Ms) is lower than out of plane configuration because of the easy axis of magnetization is perpendicular to nanowire axis. These magnetic nanowires could be utilized for applications such as spintronic devices, high density magnetic storage, and magnetic sensor applications

  9. Preparation and characterization of electrodeposited cobalt nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Irshad, M. I., E-mail: imrancssp@gmail.com; Mohamed, N. M., E-mail: noranimuti-mohamed@petronas.com.my [Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, 31750 PERAK (Malaysia); Ahmad, F., E-mail: faizahmad@petronas.com.my; Abdullah, M. Z., E-mail: zaki-abdullah@petronas.com.my [Department of Mechanical Engineering, Universiti Teknologi PETRONAS, 31750 PERAK (Malaysia)

    2014-10-24

    Electrochemical deposition technique has been used to deposit cobalt nanowires into the nano sized channels of Anodized Aluminium Oxide (AAO) templates. CoCl{sub 2}Ðœ‡6H2O salt solution was used, which was buffered with H{sub 3}BO{sub 3} and acidified by dilute H{sub 2}SO{sub 4} to increase the plating life and control pH of the solution. Thin film of copper around 150 nm thick on one side of AAO template coated by e-beam evaporation system served as cathode to create electrical contact. FESEM analysis shows that the as-deposited nanowires are highly aligned, parallel to one another and have high aspect ratio with a reasonably high pore-filing factor. The TEM results show that electrodeposited cobalt nanowires are crystalline in nature. The Hysteresis loop shows the magnetization properties for in and out of plane configuration. The in plane saturation magnetization (Ms) is lower than out of plane configuration because of the easy axis of magnetization is perpendicular to nanowire axis. These magnetic nanowires could be utilized for applications such as spintronic devices, high density magnetic storage, and magnetic sensor applications.

  10. Bacterial Nail Infection (Paronychia)

    Science.gov (United States)

    ... of nail infection is often caused by a bacterial infection but may also be caused by herpes, a ... to a type of yeast called Candida , or bacterial infection, and this may lead to abnormal nail growth. ...

  11. Prevention of bacterial adhesion

    DEFF Research Database (Denmark)

    Klemm, Per; Vejborg, Rebecca Munk; Hancock, Viktoria

    2010-01-01

    Management of bacterial infections is becoming increasingly difficult due to the emergence and increasing prevalence of bacterial pathogens that are resistant to available antibiotics. Conventional antibiotics generally kill bacteria by interfering with vital cellular functions, an approach that....... As such, adhesion represents the Achilles heel of crucial pathogenic functions. It follows that interference with adhesion can reduce bacterial virulence. Here, we illustrate this important topic with examples of techniques being developed that can inhibit bacterial adhesion. Some of these will...

  12. Platinum-Coated Nickel Nanowires as Oxygen-Reducing Electrocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Alia, Shaun M [National Renewable Energy Laboratory (NREL); Larsen, Brian A [National Renewable Energy Laboratory (NREL); Pylypenko, Svitlana [ORNL; Cullen, David A [ORNL; Diercks, David R [Colorado School of Mines, Golden; Neyerlin, Kenneth C [National Renewable Energy Laboratory (NREL); Kocha, Shyam S [National Renewable Energy Laboratory (NREL); Pivovar, Bryan [Los Alamos National Laboratory (LANL)

    2014-01-01

    Platinum (Pt)-coated nickel (Ni) nanowires (PtNiNWs) are synthesized by the partial spontaneous galvanic displacement of NiNWs, with a diameter of 150 250 nm and a length of 100 200 m. PtNiNWs are electrochemically characterized for oxygen reduction (ORR) in rotating disk electrode half-cells with an acidic electrolyte and compared to carbon-supported Pt (Pt/HSC) and a polycrystalline Pt electrode. Like other extended surface catalysts, the nanowire morphology yields significant gains in ORR specific activity compared to Pt/HSC. Unlike other extended surface approaches, the resultant materials have yielded exceptionally high surface areas, greater than 90 m2 gPt 1. These studies have found that reducing the level of Pt displacement increases Pt surface area and ORR mass activity. PtNiNWs produce a peak mass activity of 917 mA mgPt 1, 3.0 times greater than Pt/HSC and 2.1 times greater than the U.S. Department of Energy target for proton-exchange membrane fuel cell activity.

  13. Chemical beam epitaxy growth of III–V semiconductor nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Mohummed Noori, Farah T. [University of Baghdad , College of science, Physics department , Jadiriya ,Baghdad (Iraq)

    2013-12-16

    Indium- Arsenide (InAs) nanowires were grown in a high vacuum chemical beam epitaxy (CBE) unit on InAs(111) wafers substrates at 425–454°C. Two types of nanogold were used as orientation catalyst, 40nm and 80nm. The measurements were performed using scanning electron microscopy showed that uniform nanowires. The nanowires orient vertically in the InAs nanowire scanning electron microscopy of an array 80nm diameter InAs nanowire with length is in the range 0.5–1 μm and of an array 40nm diameter with length is in the range 0.3–0.7μm. The nanowire length with growth time shows that the linear increase of nanowires start to grow as soon as TMIn is available. The growth rate with temperature was studied.

  14. Silicon carbide nanowires synthesized with phenolic resin and silicon powders

    Science.gov (United States)

    Zhao, Hongsheng; Shi, Limin; Li, Ziqiang; Tang, Chunhe

    2009-02-01

    Large-scale silicon carbide nanowires with the lengths up to several millimeters were synthesized by a coat-mix, moulding, carbonization, and high-temperature sintering process, using silicon powder and phenolic resin as the starting materials. Ordinary SiC nanowires, bamboo-like SiC nanowires, and spindle SiC nanochains are found in the fabricated samples. The ordinary SiC nanowire is a single-crystal SiC phase with a fringe spacing of 0.252 nm along the [1 1 1] growth direction. Both of the bamboo-like SiC nanowires and spindle SiC nanochains exhibit uniform periodic structures. The bamboo-like SiC nanowires consist of amorphous stem and single-crystal knots, while the spindle SiC nanochains consist of uniform spindles which grow uniformly on the entire nanowires.

  15. A detailed study of magnetization reversal in individual Ni nanowires

    KAUST Repository

    Vilanova Vidal, Enrique

    2015-01-19

    Magnetic nanowires have emerged as essential components for a broad range of applications. In many cases, a key property of these components is the switching field, which is studied as a function of the angle between the field and the nanowire. We found remarkable differences of up to 100% between the switching fields of different nanowires from the same fabrication batch. Our experimental results and micromagnetic simulations indicate that the nanowires exhibit a single domain behavior and that the switching mechanism includes vortex domain wall motion across the nanowire. The differences between the switching fields are attributed to different cross-sections of the nanowires, as found by electron microscopy. While a circular cross-section yields the smallest switching field values, any deviation from this shape results in an increase of the switching field. The shape of the nanowires\\' cross-sections is thus a critical parameter that has not been previously taken into account.

  16. Tunable magnetic nanowires for biomedical and harsh environment applications

    Science.gov (United States)

    Ivanov, Yurii P.; Alfadhel, Ahmed; Alnassar, Mohammed; Perez, Jose E.; Vazquez, Manuel; Chuvilin, Andrey; Kosel, Jürgen

    2016-04-01

    We have synthesized nanowires with an iron core and an iron oxide (magnetite) shell by a facile low-cost fabrication process. The magnetic properties of the nanowires can be tuned by changing shell thicknesses to yield remarkable new properties and multi-functionality. A multi-domain state at remanence can be obtained, which is an attractive feature for biomedical applications, where a low remanence is desirable. The nanowires can also be encoded with different remanence values. Notably, the oxidation process of single-crystal iron nanowires halts at a shell thickness of 10 nm. The oxide shell of these nanowires acts as a passivation layer, retaining the magnetic properties of the iron core even during high-temperature operations. This property renders these core-shell nanowires attractive materials for application to harsh environments. A cell viability study reveals a high degree of biocompatibility of the core-shell nanowires.

  17. Nanoscale characterization of CoPt/Pt multilayer nanowires

    International Nuclear Information System (INIS)

    CoPt/Pt multilayer nanowires have been successfully fabricated by a dc electrodeposition technique into anodic aluminium oxide (AAO) templates, and their chemistry and crystal structure characterized at the nanoscale. It was found that each individual multilayered nanowire had a regular periodic structure like bamboo. However, the periodicity of diverse nanowires from the same specimen varied in magnitude. The Pt layers grew to the full width of the AAO template. However, the cobalt-rich layers in each nanowire did not fully fill the template pores during growth, resulting in a repeatably oscillating nanowire diameter. The chemical composition of multilayer nanowires was measured to be (Co72Pt28/Pt)n. Both the Co72Pt28 and Pt layers were polycrystalline, consisting of fcc nanocrystals <5 nm in size. The variable nanowire periodicity and wire diameter will result in variable mechanical strength, resistance and GMR effect

  18. Tunable magnetic nanowires for biomedical and harsh environment applications

    KAUST Repository

    Ivanov, Yurii P.

    2016-04-13

    We have synthesized nanowires with an iron core and an iron oxide (magnetite) shell by a facile low-cost fabrication process. The magnetic properties of the nanowires can be tuned by changing shell thicknesses to yield remarkable new properties and multi-functionality. A multi-domain state at remanence can be obtained, which is an attractive feature for biomedical applications, where a low remanence is desirable. The nanowires can also be encoded with different remanence values. Notably, the oxidation process of single-crystal iron nanowires halts at a shell thickness of 10 nm. The oxide shell of these nanowires acts as a passivation layer, retaining the magnetic properties of the iron core even during high-temperature operations. This property renders these core-shell nanowires attractive materials for application to harsh environments. A cell viability study reveals a high degree of biocompatibility of the core-shell nanowires.

  19. Nanoporous Thin Film Templates for the Fabrication of Nanowires and Nanotubes

    DEFF Research Database (Denmark)

    Bordo, Kirill

    2011-01-01

    templates on free-standing thin-film substrates was developed. The method involves the use of water-soluble NaCl release layer produced by means of e-beam evaporation in high vacuum. The PAA templates are fabricated via anodization of thin Al films supported by thin layers of e-beam evaporated silicon oxide...... of nanowires or nanotubes are obtained. Such arrays can be subsequently integrated into e.g. solar cells and other electronic devices. This thesis is focused on the fabrication of thin-film porous anodic alumina (PAA) templates on different substrates. The fabrication of organic nanowires and...... nanotubes via melt- or solution-assisted wetting of PAA templates is also studied. Supported PAA templates were obtained by anodization of thin Al films. Thin Al films produced by evaporation of Al onto different substrates were studied by SEM and AFM. It has been found that the structure and surface...

  20. Raman Spectroscopy of InAs Based Nanowires & Electronic Characterization of Heterostructure InAs/GaInAs Nanowires

    DEFF Research Database (Denmark)

    Tanta, Rawa

    relation to the nanowire surface facets. We present controlled oxidation experiments on InAs nanowires enabled by fabrication of micro-trenches in the substrate and the electronic properties of the oxidized nanowire were also studied. Finally, we present an attempt to detect the LO phonon-plasmon coupled......The work presented in this thesis represents two main topics. The first one, which covers a bigger volume of the thesis, is mainly about Raman spectroscopy on individual InAs based nanowires. The second part presents electronic characterization of heterostructure InAs/GaInAs nanowires. Raman...... transport measurements....

  1. Novel SiOC nanocomposites for high-yield preparation of ultra-large-scale SiC nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Xiaodong; Huang Xiaoxiao; Wen Guangwu; Geng Xin; Zhang Tao; Bai Hongwei [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zhu Jiandong, E-mail: wgw@hitwh.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology at Weihai, Weihai 264209 (China)

    2010-09-24

    Novel SiOC nanocomposites were successfully synthesized from commercial silica sol and sucrose via a simply designed route. The formation of SiOC nanocomposites was studied using thermogravimetry and differential scanning calorimetry. The synthesized nanocomposites were characterized by Fourier transform infrared spectroscopy, x-ray fluorescence spectrometer, x-ray photoelectron spectroscopy, x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results indicate that the synthesized composites are amorphous in nature and homogeneous with the microstructure of close packed SiO{sub 2} and carbon at nanoscale. The SiOC nanocomposites exhibit very high reactivity and can be annealed to produce SiC nanocrystals at 1200 deg. C which is about 300 deg. C lower than the value obtained by thermodynamic calculation. Ultra-large-scale {beta}-SiC nanowires with high quality were prepared by directly annealing the synthesized SiOC nanocomposites at 1500 deg. C under Ar atmosphere, where the yield of SiC nanowires was up to 59%. The SiC nanowires grow along the [111] direction with highly uniform diameters of about 100 nm. Experimental results indicate that the close contact between SiO{sub 2} and carbon at nanoscale plays a vital role in the high yield of SiC nanowires. The present work provides an efficient strategy for the large scale production of high-quality SiC nanowires.

  2. Novel SiOC nanocomposites for high-yield preparation of ultra-large-scale SiC nanowires

    International Nuclear Information System (INIS)

    Novel SiOC nanocomposites were successfully synthesized from commercial silica sol and sucrose via a simply designed route. The formation of SiOC nanocomposites was studied using thermogravimetry and differential scanning calorimetry. The synthesized nanocomposites were characterized by Fourier transform infrared spectroscopy, x-ray fluorescence spectrometer, x-ray photoelectron spectroscopy, x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results indicate that the synthesized composites are amorphous in nature and homogeneous with the microstructure of close packed SiO2 and carbon at nanoscale. The SiOC nanocomposites exhibit very high reactivity and can be annealed to produce SiC nanocrystals at 1200 deg. C which is about 300 deg. C lower than the value obtained by thermodynamic calculation. Ultra-large-scale β-SiC nanowires with high quality were prepared by directly annealing the synthesized SiOC nanocomposites at 1500 deg. C under Ar atmosphere, where the yield of SiC nanowires was up to 59%. The SiC nanowires grow along the [111] direction with highly uniform diameters of about 100 nm. Experimental results indicate that the close contact between SiO2 and carbon at nanoscale plays a vital role in the high yield of SiC nanowires. The present work provides an efficient strategy for the large scale production of high-quality SiC nanowires.

  3. Growth and process modeling studies of nickel-catalyzed metalorganic chemical vapor deposition of GaN nanowires

    Science.gov (United States)

    Burke, Robert A.; Lamborn, Daniel R.; Weng, Xiaojun; Redwing, Joan M.

    2009-06-01

    A combination of experimental and computational fluid dynamics-based reactor modeling studies were utilized to study the effects of process conditions on GaN nanowire growth by metalorganic chemical vapor deposition (MOCVD) in an isothermal tube reactor. The GaN nanowires were synthesized on (0 0 0 1) sapphire substrates using nickel thin films as a catalyst. GaN nanowire growth was observed over a furnace temperature range of 800-900 °C at V/III ratios ranging from 33 to 67 and was found to be strongly dependent on the position of the substrate relative to the group III inlet tube. The modeling studies revealed that nanowire growth consistently occurred in a region in the reactor where the GaN thin-film deposition rate was reduced and the gas phase consisted primarily of intermediate species produced by the reaction and decomposition of trimethylgallium-ammonia adduct compounds. The GaN nanowires exhibited a predominant [1 1 2¯ 0] growth direction. Photoluminescence measurements revealed an increase in the GaN near-band edge emission intensity and a reduction in the deep-level yellow luminescence with increasing growth temperature and V/III ratio.

  4. Surface superconductivity in thin cylindrical Bi nanowire.

    Science.gov (United States)

    Tian, Mingliang; Wang, Jian; Ning, Wei; Mallouk, Thomas E; Chan, Moses H W

    2015-03-11

    The physical origin and the nature of superconductivity in nanostructured Bi remains puzzling. Here, we report transport measurements of individual cylindrical single-crystal Bi nanowires, 20 and 32 nm in diameter. In contrast to nonsuperconducting Bi nanoribbons with two flat surfaces, cylindrical Bi nanowires show superconductivity below 1.3 K. However, their superconducting critical magnetic fields decrease with their diameter, which is the opposite of the expected behavior for thin superconducting wires. Quasiperiodic oscillations of magnetoresistance were observed in perpendicular fields but were not seen in the parallel orientation. These results can be understood by a model of surface superconductivity with an enhanced surface-to-bulk volume in small diameter wires, where the superconductivity originates from the strained surface states of the nanowires due to the surface curvature-induced stress. PMID:25658139

  5. Thermoelectric properties of semiconductor nanowire networks

    Science.gov (United States)

    Roslyak, Oleksiy; Piryatinski, Andrei

    2016-03-01

    To examine the thermoelectric (TE) properties of a semiconductor nanowire (NW) network, we propose a theoretical approach mapping the TE network on a two-port network. In contrast to a conventional single-port (i.e., resistor) network model, our model allows for large scale calculations showing convergence of TE figure of merit, ZT, with an increasing number of junctions. Using this model, numerical simulations are performed for the Bi2Te3 branched nanowire (BNW) and Cayley tree NW (CTNW) network. We find that the phonon scattering at the network junctions plays a dominant role in enhancing the network ZT. Specifically, disordered BNW and CTNW demonstrate an order of magnitude higher ZT enhancement compared to their ordered counterparts. Formation of preferential TE pathways in CTNW makes the network effectively behave as its BNW counterpart. We provide formalism for simulating large scale nanowire networks hinged upon experimentally measurable TE parameters of a single T-junction.

  6. Modelling of electron beam induced nanowire attraction

    Science.gov (United States)

    Bitzer, Lucas A.; Speich, Claudia; Schäfer, David; Erni, Daniel; Prost, Werner; Tegude, Franz J.; Benson, Niels; Schmechel, Roland

    2016-04-01

    Scanning electron microscope (SEM) induced nanowire (NW) attraction or bundling is a well known effect, which is mainly ascribed to structural or material dependent properties. However, there have also been recent reports of electron beam induced nanowire bending by SEM imaging, which is not fully explained by the current models, especially when considering the electro-dynamic interaction between NWs. In this article, we contribute to the understanding of this phenomenon, by introducing an electro-dynamic model based on capacitor and Lorentz force interaction, where the active NW bending is stimulated by an electromagnetic force between individual wires. The model includes geometrical, electrical, and mechanical NW parameters, as well as the influence of the electron beam source parameters and is validated using in-situ observations of electron beam induced GaAs nanowire (NW) bending by SEM imaging.

  7. Rare earth silicide nanowires on silicon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Wanke, Martina

    2008-11-10

    The growth, structure and electronic properties of rare earth silicide nanowires are investigated on planar and vicinal Si(001) und Si(111) surfaces with scanning tunneling microscopy (STM), low energy electron diffraction (LEED) and angle-resolved photoelectron spectroscopy (ARPES). On all surfaces investigated within this work hexagonal disilicides are grown epitaxially with a lattice mismatch of -2.55% up to +0.83% along the hexagonal a-axis. Along the hexagonal c-axis the lattice mismatch is essentially larger with 6.5%. On the Si(001)2 x 1 surface two types of nanowires are grown epitaxially. The socalled broad wires show a one-dimensional metallic valence band structure with states crossing the Fermi level. Along the nanowires two strongly dispersing states at the anti J point and a strongly dispersing state at the anti {gamma} point can be observed. Along the thin nanowires dispersing states could not be observed. Merely in the direction perpendicular to the wires an intensity variation could be observed, which corresponds to the observed spacial structure of the thin nanowires. The electronic properties of the broad erbium silicide nanowires are very similar to the broad dysprosium silicide nanowires. The electronic properties of the DySi{sub 2}-monolayer and the Dy{sub 3}Si{sub 5}-multilayer on the Si(111) surface are investigated in comparison to the known ErSi{sub 2}/Si(111) and Er{sub 3}Si{sub 5}/Si(111) system. The positions and the energetic locations of the observed band in the surface Brillouin zone will be confirmed for dysprosium. The shape of the electron pockets in the (vector)k {sub parallel} space is elliptical at the anti M points, while the hole pocket at the anti {gamma} point is showing a hexagonal symmetry. On the Si(557) surface the structural and electronic properties depend strongly on the different preparation conditions likewise, in particular on the rare earth coverage. At submonolayer coverage the thin nanowires grow in wide areas

  8. Efficient water reduction with gallium phosphide nanowires

    Science.gov (United States)

    Standing, Anthony; Assali, Simone; Gao, Lu; Verheijen, Marcel A.; van Dam, Dick; Cui, Yingchao; Notten, Peter H. L.; Haverkort, Jos E. M.; Bakkers, Erik P. A. M.

    2015-07-01

    Photoelectrochemical hydrogen production from solar energy and water offers a clean and sustainable fuel option for the future. Planar III/V material systems have shown the highest efficiencies, but are expensive. By moving to the nanowire regime the demand on material quantity is reduced, and new materials can be uncovered, such as wurtzite gallium phosphide, featuring a direct bandgap. This is one of the few materials combining large solar light absorption and (close to) ideal band-edge positions for full water splitting. Here we report the photoelectrochemical reduction of water, on a p-type wurtzite gallium phosphide nanowire photocathode. By modifying geometry to reduce electrical resistance and enhance optical absorption, and modifying the surface with a multistep platinum deposition, high current densities and open circuit potentials were achieved. Our results demonstrate the capabilities of this material, even when used in such low quantities, as in nanowires.

  9. Field-emission properties of patterned ZnO nanowires on 2.5D MEMS substrate

    Energy Technology Data Exchange (ETDEWEB)

    Park, Seung-Beum; Kim, Byeong-Guk; Kim, Jeong-Yeon; Jung, Tae-Hwan; Lim, Dong-Gun; Park, Jae-Hwan [Chungju National University, Department of Electronic Engineering, Chungbuk (Korea, Republic of); Park, Jae-Gwan [Korea Institute of Science and Technology, Nano-Materials Center, Seoul (Korea, Republic of)

    2011-01-15

    We fabricated a nanowire-based field-emission display (FED) device on a 2.5D substrate using a photolithography, lift-off, thermal-evaporation, and plasma-etching process. We first fabricated a 3 x 3 array of microholes (diameter = 400 {mu}m and depth = 50 {mu}m) on a Si substrate and fabricated ZnO nanowires inside the microholes by using a thermal CVD process. The field-emission pattern image of the 3 x 3 array of microholes was clearly apparent. The threshold emission field was ca. 5.6 V/{mu}m and we obtained considerable brightness when the applied voltage was 1900 V (i.e. 6.3 V/{mu}m). Because the fabrication processes used in this study are standard semiconductor fabrication routes, the study suggests the feasibility of mass producing a nanowire-based FED device. (orig.)

  10. Magneto-mechanical modeling study of CO-based amorphous micro- and nanowires for acoustic sensing medical applications

    Science.gov (United States)

    Atitoaie, Alexandru; Stancu, Alexandru; Ovari, Tibor-Adrian; Lupu, Nicoleta; Chiriac, Horia

    2016-04-01

    Magnetic nanowires are potential candidates for substituting, within enhanced cochlear implants, the role played by hair cilia from the inner ear, which are responsible for the transduction of acoustic vibrations into electric signals. The sound waves pressure that is bending the magnetic wires induces stresses that are leading to changes in magnetic properties, such as magnetization and permeability. These changes can be detected by a GMR sensor placed below the nanowire array or, in the case of different designs, by a pick-up coil wrapped around the fixed-end of the wires. For the latter case, we are studying the stress distributions caused by bending deformations using the COMSOL finite element software package. We are also proposing a theoretical method for the evaluation of magnetic permeability variation vs. induced stress dependence. The study is performed on CoFeSiB amorphous micro- and nanowires subjected to mechanical perturbations similar to the ones produced by sound pressure waves.

  11. Fabrication of silicon carbide nanowires/carbon nanotubes heterojunction arrays by high-flux Si ion implantation.

    Science.gov (United States)

    Liu, Huaping; Cheng, Guo-An; Liang, Changlin; Zheng, Ruiting

    2008-06-18

    An array of silicon carbide nanowire (SiCNW)-carbon nanotube (CNT) heterojunctions was fabricated by high-flux Si ion implantation into a multi-walled carbon nanotube (MWCNT) array with a metal vapor vacuum arc (MEVVA) ion source. Under Si irradiation, the top part of a CNT array was gradually transformed into an amorphous nanowire array with increasing Si dose while the bottom part still remained a CNT structure. X-ray photoelectron spectroscopy (XPS) analysis shows that the SiC compound was produced in the nanowire part even at the lower Si dose of 5 × 10(16) ions cm(-2), and the SiC amount increased with increasing the Si dose. Therefore, the fabrication of a SiCNW-CNT heterojunction array with the MEVVA technique has been successfully demonstrated. The corresponding formation mechanism of SiCNWs was proposed. PMID:21825818

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

    Science.gov (United States)

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

    2015-01-01

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

  13. Realization of microwave quantum circuits using hybrid superconducting-semiconducting nanowire Josephson elements

    OpenAIRE

    Lange, G; van Heck, B.; Bruno, A.; Van Woerkom, D.J.; Geresdi, A.; Plissard, S.R.; Bakkers, E. P. A. M.; Akhmerov, A.R.; Di Carlo, L.

    2015-01-01

    We report the realization of quantum microwave circuits using hybrid superconductor-semiconductor Josephson elements comprised of InAs nanowires contacted by NbTiN. Capacitively shunted single elements behave as transmon circuits with electrically tunable transition frequencies. Two-element circuits also exhibit transmonlike behavior near zero applied flux but behave as flux qubits at half the flux quantum, where nonsinusoidal current-phase relations in the elements produce a double-well Jose...

  14. Extended Two Dimensional Nanotube and Nanowire Surfaces as Fuel Cell Catalysts

    OpenAIRE

    Alia, Shaun Michael

    2011-01-01

    Extended network nanomaterials of platinum (Pt), silver (Ag), palladium (Pd), and gold (Au) are synthesized and characterized as proton exchange membrane (PEMFC), hydroxide exchange membrane (HEMFC), and direct alcohol (DAFC) fuel cell catalysts.Porous Pt nanotubes (PPtNTs), 5 nm thick, are synthesized by the galvanic displacement of Ag nanowires (AgNWs) for PEMFCs and DAFCs. PPtNTs produce oxygen reduction (ORR) and durability characteristics significantly higher than supported Pt nanopartic...

  15. Plant Natural Products Targeting Bacterial Virulence Factors.

    Science.gov (United States)

    Silva, Laura Nunes; Zimmer, Karine Rigon; Macedo, Alexandre José; Trentin, Danielle Silva

    2016-08-24

    Decreased antimicrobial efficiency has become a global public health issue. The paucity of new antibacterial drugs is evident, and the arsenal against infectious diseases needs to be improved urgently. The selection of plants as a source of prototype compounds is appropriate, since plant species naturally produce a wide range of secondary metabolites that act as a chemical line of defense against microorganisms in the environment. Although traditional approaches to combat microbial infections remain effective, targeting microbial virulence rather than survival seems to be an exciting strategy, since the modulation of virulence factors might lead to a milder evolutionary pressure for the development of resistance. Additionally, anti-infective chemotherapies may be successfully achieved by combining antivirulence and conventional antimicrobials, extending the lifespan of these drugs. This review presents an updated discussion of natural compounds isolated from plants with chemically characterized structures and activity against the major bacterial virulence factors: quorum sensing, bacterial biofilms, bacterial motility, bacterial toxins, bacterial pigments, bacterial enzymes, and bacterial surfactants. Moreover, a critical analysis of the most promising virulence factors is presented, highlighting their potential as targets to attenuate bacterial virulence. The ongoing progress in the field of antivirulence therapy may therefore help to translate this promising concept into real intervention strategies in clinical areas. PMID:27437994

  16. Biodiversity of aerobic endospore-forming bacterial species occurring in Yanyanku and Ikpiru, fermented seeds of Hibiscus sabdariffa used to produce food condiments in Benin

    DEFF Research Database (Denmark)

    Agbobatinkpo, Pélagie B.; Thorsen, Line; Nielsen, Dennis Sandris;

    2013-01-01

    Yanyanku and Ikpiru made by the fermentation of Malcavene bean (Hibiscus sabdariffa) are used as functional additives for Parkia biglobosa seed fermentations in Benin. A total of 355 aerobic endospore-forming bacteria (AEFB) isolated from Yanyanku and Ikpiru produced in northern and southern Benin...

  17. Bacterial Probiotic Modulation of Dendritic Cells

    OpenAIRE

    Drakes, Maureen; Blanchard, Thomas; Czinn, Steven

    2004-01-01

    Intestinal dendritic cells are continually exposed to ingested microorganisms and high concentrations of endogenous bacterial flora. These cells can be activated by infectious agents and other stimuli to induce T-cell responses and to produce chemokines which recruit other cells to the local environment. Bacterial probiotics are of increasing use against intestinal disorders such as inflammatory bowel disease. They act as nonpathogenic stimuli within the gut to regain immunologic quiescence. ...

  18. Smooth Nanowire/Polymer Composite Transparent Electrodes

    KAUST Repository

    Gaynor, Whitney

    2011-04-29

    Smooth composite transparent electrodes are fabricated via lamination of silver nanowires into the polymer poly-(4,3-ethylene dioxythiophene): poly(styrene-sulfonate) (PEDOT:PSS). The surface roughness is dramatically reduced compared to bare nanowires. High-efficiency P3HT:PCBM organic photovoltaic cells can be fabricated using these composites, reproducing the performance of cells on indium tin oxide (ITO) on glass and improving the performance of cells on ITO on plastic. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Fabricating Nanoscale DNA Patterns with Gold Nanowires

    OpenAIRE

    Chen, Yulin; Kung, Sheng-Chin; Taggart, David K.; Halpern, Aaron R.; Penner, Reginald M.; Corn, Robert M.

    2010-01-01

    Surface patterns of single-stranded DNA (ssDNA) consisting of nanoscale lines as thin as 40 nm were fabricated on polymer substrates for nanotechnology and bioaffinity sensing applications. Large scale arrays (with areas up to 4 cm2) of ssDNA “nanolines” were created on streptavidin-coated polymer (PDMS) surfaces by transferring biotinylated ssDNA from a master pattern of gold nanowires attached to a glass substrate. The gold nanowires were first formed on the glass substrate by the process o...

  20. Synchrotron characterization of functional tin dioxide nanowires

    International Nuclear Information System (INIS)

    Wire-like crystals of tin dioxide were synthesized by a gas-transport technique. The wires, of mainly nanometric diameters, were characterized by spectroscopy and microscopy techniques with the use of highly brilliant and intense synchrotron radiation. We studied the influence of the surface chemical state and the oxygen vacancies on the atomic and electronic structure of the nanowires. The surface of the nanowires is covered by a few nanometers of tin suboxides. The lack of oxygen over the surface layers leads to specific sub-zone formation in a gap, as shown by synchrotron studies

  1. Photoresponse in arrays of thermoelectric nanowire junctions

    Science.gov (United States)

    Huber, T. E.; Scott, R.; Johnson, S.; Brower, T.; Belk, J. H.; Hunt, J. H.

    2013-07-01

    We report the first demonstration of optical detection by thermoelectric nanowire junctions. We employed devices composed of bismuth nanowire arrays which are capped with a transparent indium tin oxide electrode. The incident surface features very low optical reflectivity and enhanced light trapping. The unique attributes of the thermoelectric arrays are the combination of strong temporal and optical wavelength dependences of the photocurrent. Under infrared illumination, the signal can be completely described by thermoelectric effects considering cooling rates given by heat diffusion through the array. In addition, under visible illumination, we observe a photovoltaic response.

  2. Synthesis and Characterization of Glassy Carbon Nanowires

    Directory of Open Access Journals (Sweden)

    C. M. Lentz

    2011-01-01

    Full Text Available The advent of carbon-based micro- and nanoelectromechanical systems has revived the interest in glassy carbon, whose properties are relatively unknown at lower dimensions. In this paper, electrical conductivity of individual glassy carbon nanowires was measured as a function of microstructure (controlled by heat treatment temperature and ambient temperature. The semiconducting nanowires with average diameter of 150 nm were synthesized from polyfurfuryl alcohol precursors and characterized using transmission electron and Raman microscopy. DC electrical measurements made at 90 K to 450 K show very strong dependence of temperature, following mixed modes of activation energy and hopping-based conduction.

  3. Burnout current density of bismuth nanowires

    Science.gov (United States)

    Cornelius, T. W.; Picht, O.; Müller, S.; Neumann, R.; Völklein, F.; Karim, S.; Duan, J. L.

    2008-05-01

    Single bismuth nanowires with diameters ranging from 100nmto1μm were electrochemically deposited in ion track-etched single-pore polycarbonate membranes. The maximum current density the wires are able to carry was investigated by ramping up the current until failure occurred. It increases by three to four orders of magnitude for nanowires embedded in the template compared to bulk bismuth and rises with diminishing diameter. Simulations show that the wires are heated up electrically to the melting temperature. Since the surface-to-volume ratio rises with diminishing diameter, thinner wires dissipate the heat more efficiently to the surrounding polymer matrix and, thus, can tolerate larger current densities.

  4. Synchrotron characterization of functional tin dioxide nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Domashevskaya, E. P., E-mail: ftt@phys.vsu.ru; Chuvenkova, O. A.; Turishchev, S. Yu. [Voronezh State University, Voronezh (Russian Federation)

    2015-12-31

    Wire-like crystals of tin dioxide were synthesized by a gas-transport technique. The wires, of mainly nanometric diameters, were characterized by spectroscopy and microscopy techniques with the use of highly brilliant and intense synchrotron radiation. We studied the influence of the surface chemical state and the oxygen vacancies on the atomic and electronic structure of the nanowires. The surface of the nanowires is covered by a few nanometers of tin suboxides. The lack of oxygen over the surface layers leads to specific sub-zone formation in a gap, as shown by synchrotron studies.

  5. Copper Nanowires as Fully Transparent Conductive Electrodes

    OpenAIRE

    Huizhang Guo; Na Lin; Yuanzhi Chen; Zhenwei Wang; Qingshui Xie; Tongchang Zheng; Na Gao; Shuping Li; Junyong Kang; Duanjun Cai; Dong-Liang Peng

    2013-01-01

    In pondering of new promising transparent conductors to replace the cost rising tin-doped indium oxide (ITO), metal nanowires have been widely concerned. Herein, we demonstrate an approach for successful synthesis of long and fine Cu nanowires (NWs) through a novel catalytic scheme involving nickel ions. Such Cu NWs in high aspect ratio (diameter of 16.2 ± 2 nm and length up to 40 μm) provide long distance for electron transport and, meanwhile, large space for light transmission. Transparent ...

  6. Branched silver nanowires as controllable plasmon routers.

    Science.gov (United States)

    Fang, Yurui; Li, Zhipeng; Huang, Yingzhou; Zhang, Shunping; Nordlander, Peter; Halas, Naomi J; Xu, Hongxing

    2010-05-12

    Using polarization dependent scattering spectroscopy, we investigate plasmon propagation on branched silver nanowires. By controlling the polarization of the incident laser light, the wire plasmons can be routed into different wire branches and result in light emission from the corresponding wire ends. This routing behavior is found to be strongly dependent on the wavelength of light. Thus for certain incident polarizations, light of different wavelength will be routed into different branches. The branched nanowire can thus serve as a controllable router and multiplexer in integrated plasmonic circuits. PMID:20420411

  7. Bacterial Community Analysis, New Exoelectrogen Isolation and Enhanced Performance of Microbial Electrochemical Systems Using Nano-Decorated Anodes

    Science.gov (United States)

    Xu, Shoutao

    Microbial electrochemical systems (MESs) have attracted much research attention in recent years due to their promising applications in renewable energy generation, bioremediation, and wastewater treatment. In a MES, microorganisms interact with electrodes via electrons, catalyzing oxidation and reduction reactions at the anode and the cathode. The bacterial community of a high power mixed consortium MESs (maximum power density is 6.5W/m2) was analyzed by using denature gradient gel electrophoresis (DGGE) and 16S DNA clone library methods. The bacterial DGGE profiles were relatively complex (more than 10 bands) but only three brightly dominant bands in DGGE results. These results indicated there are three dominant bacterial species in mixed consortium MFCs. The 16S DNA clone library method results revealed that the predominant bacterial species in mixed culture is Geobacter sp (66%), Arcobacter sp and Citrobacter sp. These three bacterial species reached to 88% of total bacterial species. This result is consistent with the DGGE result which showed that three bright bands represented three dominant bacterial species. Exoelectrogenic bacterial strain SX-1 was isolated from a mediator-less microbial fuel cell by conventional plating techniques with ferric citrate as electron acceptor under anaerobic conditions. Phylogenetic analysis of the 16S rDNA sequence revealed that it was related to the members of Citrobacter genus with Citrobacter sp. sdy-48 being the most closely related species. The bacterial strain SX-1 produced electricity from citrate, acetate, glucose, sucrose, glycerol, and lactose in MFCs with the highest current density of 205 mA/m2 generated from citrate. Cyclic voltammetry analysis indicated that membrane associated proteins may play an important role in facilitating electron transfer from the bacteria to the electrode. This is the first study that demonstrates that Citrobacter species can transfer electrons to extracellular electron acceptors

  8. Diamond Nanowires: A Novel Platform for Electrochemistry and Matrix-Free Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Sabine Szunerits

    2015-05-01

    Full Text Available Over the last decades, carbon-based nanostructures have generated a huge interest from both fundamental and technological viewpoints owing to their physicochemical characteristics, markedly different from their corresponding bulk states. Among these nanostructured materials, carbon nanotubes (CNTs, and more recently graphene and its derivatives, hold a central position. The large amount of work devoted to these materials is driven not only by their unique mechanical and electrical properties, but also by the advances made in synthetic methods to produce these materials in large quantities with reasonably controllable morphologies. While much less studied than CNTs and graphene, diamond nanowires, the diamond analogue of CNTs, hold promise for several important applications. Diamond nanowires display several advantages such as chemical inertness, high mechanical strength, high thermal and electrical conductivity, together with proven biocompatibility and existence of various strategies to functionalize their surface. The unique physicochemical properties of diamond nanowires have generated wide interest for their use as fillers in nanocomposites, as light detectors and emitters, as substrates for nanoelectronic devices, as tips for scanning probe microscopy as well as for sensing applications. In the past few years, studies on boron-doped diamond nanowires (BDD NWs focused on increasing their electrochemical active surface area to achieve higher sensitivity and selectivity compared to planar diamond interfaces. The first part of the present review article will cover the promising applications of BDD NWS for label-free sensing. Then, the potential use of diamond nanowires as inorganic substrates for matrix-free laser desorption/ionization mass spectrometry, a powerful label-free approach for quantification and identification of small compounds, will be discussed.

  9. Infrared photodetectors in heterostructure nanowires.

    Science.gov (United States)

    Pettersson, H; Trägårdh, J; Persson, A I; Landin, L; Hessman, D; Samuelson, L

    2006-02-01

    We report on spectrally resolved photocurrent measurements on single self-assembled nanowire heterostructures. The wires, typically 3 microm long with an average diameter of 85 nm, consist of InAs with a 1 microm central part of InAsP. Two different sets of wires were prepared with phosphorus contents of 15+/-3% and 35+/-3%, respectively, as determined by energy-dispersive spectroscopy measurements made in transmission electron microscopy. Ohmic contacts are fabricated to the InAs ends of the wire using e-beam lithography. The conduction band offset between the InAs and InAsP regions virtually removes the dark current through the wires at low temperature. In the optical experiments, interband excitation in the phosphorus-rich part of the wires results in a photocurrent with threshold energies of about 0.65 and 0.82 eV, respectively, in qualitative agreement with the expected band gap of the two compositions. Furthermore, a strong polarization dependence is observed with an order of magnitude larger photocurrent for light polarized parallel to the wire than for light polarized perpendicular to the wire. We believe that these wires form promising candidates as nanoscale infrared polarization-sensitive photodetectors. PMID:16464040

  10. Carbon nanostructures produced through ion irradiation

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Several nanostructures we produced by ion irradiation have been reviewed in this paper. By using ions to irradiate two ultrahigh molecular weight polyethylene targets respectively, it was found that small fullerenes C20 and C26 were grown, adding two members to the fullerene family. Meanwhile, crystalline diamonds also have been produced by Ar+ ions irradiation of graphite. In the experiment of double ions Ni+ and Ar+ irradiation, nanoscale argon bubbles formed. On the other side, when multi-wall carbon nanotubes were irradiated by C+, many MWCNTs evolved to amorphous carbon nanowires and amorphous carbon nanotubes. And there are possible welding in the crossed nanotubes.

  11. Solution processed semiconductor alloy nanowire arrays for optoelectronic applications

    Science.gov (United States)

    Shimpi, Paresh R.

    In this dissertation, we use ZnO nanowire as a model system to investigate the potential of solution routes for bandgap engineering in semiconductor nanowires. Excitingly, successful Mg-alloying into ZnO nanowire arrays has been achieved using a two-step sequential hydrothermal method at low temperature (post-annealing process. Evidently, both room temperature and 40 K photoluminescence (PL) spectroscopy revealed enhanced and blue-shifted near-band-edge ultraviolet (NBE UV) emission in the Mg-alloyed ZnO (ZnMgO) nanowire arrays, compared with ZnO nanowires. The specific template of densely packed ZnO nanowires is found to be instrumental in achieving the Mg alloying in low temperature solution process. By optimizing the density of ZnO nanowires and precursor concentration, 8-10 at.% of Mg content has been achieved in ZnMgO nanowires. Post-annealing treatment is conducted in oxygen-rich and oxygen-deficient environment at different temperatures and time durations on silicon and quartz substrates in order to study the structural and optical property evolution in ZnMgO nanowire arrays. Vacuum annealed ZnMgO nanowires on both substrates retained their hexagonal structures and PL results showed the enhanced but red-shifted NBE UV emission compared to ZnO nanowires with visible emission nearly suppressed, suggesting the reduced defects concentration and improvement in crystallinity of the nanowires. On the contrast, for ambient annealed ZnMgO nanowires on silicon substrate, as the annealing temperature increased from 400°C to 900°C, intensity of visible emission peak across blue-green-yellow-red band (˜400-660 nm) increased whereas intensity of NBE UV peak decreased and completely got quenched. This might be due to interface diffusion of oxidized Si (SiOx) and formation of (Zn,Mg)1.7SiO4 epitaxially overcoated around individual ZnMgO nanowire. On the other hand, ambient annealed ZnMgO nanowires grown on quartz showed a ˜6-10 nm blue-shift in NBE UV emission

  12. Sputtered gold-coated ITO nanowires by alternating depositions from Indium and ITO targets for application in surface-enhanced Raman scattering

    Energy Technology Data Exchange (ETDEWEB)

    Setti, Grazielle O. [Institute of Chemistry, University of Campinas, Campinas, P.O. Box 6154, 13083-970 Campinas, SP (Brazil); Renato Archer Information Technology Center, Rodovia Dom Pedro I (SP-65), Km 143,6 – Amarais, 13069-901 Campinas, SP (Brazil); Mamián-López, Mónica B.; Pessoa, Priscila R.; Poppi, Ronei J. [Institute of Chemistry, University of Campinas, Campinas, P.O. Box 6154, 13083-970 Campinas, SP (Brazil); Joanni, Ednan, E-mail: ednan.joanni@cti.gov.br [Renato Archer Information Technology Center, Rodovia Dom Pedro I (SP-65), Km 143,6 – Amarais, 13069-901 Campinas, SP (Brazil); Jesus, Dosil P. [Institute of Chemistry, University of Campinas, Campinas, P.O. Box 6154, 13083-970 Campinas, SP (Brazil)

    2015-08-30

    Graphical abstract: - Highlights: • ITO nanowires were grown by the sputtering method using a new synthesis procedure. • By changing the deposition parameters the morphology and dimensions of the nanostructures were modified. • Seed layer thickness was an important factor for obtaining branched nanowires. • SERS substrates having good performance and a high application potential were produced. • The first Raman results for our substrates are already comparable to commercial substrates. - Abstract: Indium Tin oxide (ITO) nanowires were deposited by RF sputtering over oxidized silicon using ITO and Indium targets. The nanowires grew on the substrate with a catalyst layer of Indium by the vapor–liquid–solid (VLS) mechanism. Modifications in the deposition conditions affected the morphology and dimensions of the nanowires. The samples, after being covered with gold, were evaluated as surface-enhanced Raman scattering (SERS) substrates for detection of dye solutions and very good intensifications of the Raman signal were obtained. The SERS performance of the samples was also compared to that of a commercial SERS substrate and the results achieved were similar. To the best of our knowledge, this is the first time ITO nanowires were grown by the sputtering technique using oxide and metal targets.

  13. Formation of silicon nanowire packed films from metallurgical-grade silicon powder using a two-step metal-assisted chemical etching method

    Science.gov (United States)

    Ouertani, Rachid; Hamdi, Abderrahmen; Amri, Chohdi; Khalifa, Marouan; Ezzaouia, Hatem

    2014-10-01

    In this work, we use a two-step metal-assisted chemical etching method to produce films of silicon nanowires shaped in micrograins from metallurgical-grade polycrystalline silicon powder. The first step is an electroless plating process where the powder was dipped for few minutes in an aqueous solution of silver nitrite and hydrofluoric acid to permit Ag plating of the Si micrograins. During the second step, corresponding to silicon dissolution, we add a small quantity of hydrogen peroxide to the plating solution and we leave the samples to be etched for three various duration (30, 60, and 90 min). We try elucidating the mechanisms leading to the formation of silver clusters and silicon nanowires obtained at the end of the silver plating step and the silver-assisted silicon dissolution step, respectively. Scanning electron microscopy (SEM) micrographs revealed that the processed Si micrograins were covered with densely packed films of self-organized silicon nanowires. Some of these nanowires stand vertically, and some others tilt to the silicon micrograin facets. The thickness of the nanowire films increases from 0.2 to 10 μm with increasing etching time. Based on SEM characterizations, laser scattering estimations, X-ray diffraction (XRD) patterns, and Raman spectroscopy, we present a correlative study dealing with the effect of the silver-assisted etching process on the morphological and structural properties of the processed silicon nanowire films.

  14. Group IV semiconductor nanowire arrays: epitaxy in different contexts

    International Nuclear Information System (INIS)

    Epitaxy can be used to direct nanowire deposition and to influence the crystallographic orientation of nanowires during their nucleation and growth via the vapor–liquid–solid mechanism. We have investigated rapid thermal chemical vapor deposition of epitaxial Ge nanowires and have used it to separately study nanowire nucleation and growth. This work has provided important insights into deep-subeutectic Ge nanowire growth using Au catalyst particles. Germanium nanowires have also been studied as the cores in epitaxial Ge core/Si shell nanowires. We have studied the conditions under which strain-driven surface roughening and dislocations formation occur in these coaxial nanowire heterostructures. Our results indicate that suppression of Si shell surface roughening can lead to fully strained, coherent core/shell nanowires. Recently, we have used vertical arrays of Ge (1 1 1) nanowires grown at low temperatures on Si substrates to seed liquid-phase epitaxy of large-area amorphous Ge islands above the substrate surface. This work demonstrates a potential approach for dense vertical integration of Ge-based devices on Si substrates, for on-chip optoelectronics or 3D integrated circuit applications

  15. The cluster-assembled nanowires based on M12N12 (M = Al and Ga) clusters as potential gas sensors for CO, NO, and NO2 detection.

    Science.gov (United States)

    Yong, Yongliang; Jiang, Huai; Li, Xiaohong; Lv, Shijie; Cao, Jingxiao

    2016-08-01

    The advances in cluster-assembled materials where clusters serve as building blocks have opened new opportunities to develop ever more sensitive gas sensors. Here, using density functional theory calculations, the structural and electronic properties of cluster-assembled nanowires based on M12N12 (M = Al and Ga) clusters and their application as gas sensors have been investigated. Our results show that the nanowires can be produced via the coalescence of stable M12N12 fullerene-like clusters. The M12N12-based nanowires have semiconducting electrical properties with direct energy gaps, and are particularly stable at room temperature for long enough to allow for their characterization and applications. Furthermore, we found that the CO, NO, and NO2 molecules are chemisorbed on the M12N12-based nanowires with reasonable adsorption energies and apparent charge transfer. The electronic properties of the M12N12-based nanowires present dramatic changes after the adsorption of the CO, NO, and NO2 molecules, especially their electric conductivity. However, the adsorption of NO2 on the Al12N12-based nanowire is too strong, indicating an impractical recovery time as NO2 sensors. In addition to this, due to reasonable adsorption energies, apparent charge transfer, change in the electric conductivity, and the short recovery time, the Al12N12-based nanowire should be a good CO and NO sensor with quick response as well as short recovery time, while the Ga12N12-based nanowire should be a promising gas sensor for CO, NO, and NO2 detection. PMID:27424739

  16. GaN Nanowire Arrays for High-Output Nanogenerators

    KAUST Repository

    Huang, Chi-Te

    2010-04-07

    Three-fold symmetrically distributed GaN nanowire (NW) arrays have been epitaxially grown on GaN/sapphire substrates. The GaN NW possesses a triangular cross section enclosed by (0001), (2112), and (2112) planes, and the angle between the GaN NW and the substrate surface is ∼62°. The GaN NW arrays produce negative output voltage pulses when scanned by a conductive atomic force microscope in contact mode. The average of piezoelectric output voltage was about -20 mV, while 5-10% of the NWs had piezoelectric output voltages exceeding -(0.15-0.35) V. The GaN NW arrays are highly stable and highly tolerate to moisture in the atmosphere. The GaN NW arrays demonstrate an outstanding potential to be utilized for piezoelectric energy generation with a performance probably better than that of ZnO NWs. © 2010 American Chemical Society.

  17. Aligned nanowires and nanodots by directed block copolymer assembly

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Shuaigang; Yang Xiaomin; Lee, Kim Y; Ver der Veerdonk, Rene J M; Kuo, David [Seagate Technology, 47010 Kato Road, Fremont, CA 94538 (United States); Russell, Thomas P, E-mail: shuaigang.xiao@seagate.com [Department of Polymer Science and Engineering, University of Massachusetts, 120 Governors Drive, Amherst, MA 01003 (United States)

    2011-07-29

    The directed self-assembly of block copolymers (BCPs) is a promising route to generate highly ordered arrays of sub-10 nm features. Ultradense arrays of a monolayer of spherical microdomains or cylindrical microdomains oriented parallel to the surface have been produced where the lateral ordering is guided by surface patterning and the lattice defined by the patterning can be commensurate or incommensurate with the natural period of the BCP. Commensurability between the two can be used to elegantly manipulate the lateral ordering and orientation of the BCP microdomains so as to form well-aligned arrays of 1D nanowires or 2D addressable nanodots. No modification of the substrate surface, aside from the patterning, was used, making the influence of lattice mismatch and pattern amplification on the size, shape and pitch of the BCP microdomains more transparent. A skew angle between incommensurate lattices, defining a stretching or compression of the BCP chains to compensate for the lattice mismatch, is presented.

  18. Controlling growth density and patterning of single crystalline silicon nanowires

    International Nuclear Information System (INIS)

    This study examines the usage of well-patterned Au nanoparticles (NPs) as a catalyst for one-dimensional growth of single crystalline Si nanowires (NWs) through the vapor-liquid-solid (VLS) mechanism. The study reports the fabrication of monolayer Au NPs through the self-assembly of Au NPs on a 3-aminopropyltrimethoxysilane (APTMS)-modified silicon substrate. Results indicate that the spin coating time of Au NPs plays a crucial role in determining the density of Au NPs on the surface of the silicon substrate and the later catalysis growth of Si NWs. The experiments in this study employed optical lithography to pattern Au NPs, treating them as a catalyst for Si NW growth. The patterned Si NW structures easily produced and controlled Si NW density. This approach may be useful for further studies on single crystalline Si NW-based nanodevices and their properties.

  19. Highly conductive interwoven carbon nanotube and silver nanowire transparent electrodes

    Directory of Open Access Journals (Sweden)

    Andrew J Stapleton, Rakesh A Afre, Amanda V Ellis, Joe G Shapter, Gunther G Andersson, Jamie S Quinton and David A Lewis

    2013-01-01

    Full Text Available Electrodes fabricated using commercially available silver nanowires (AgNWs and single walled carbon nanotubes (SWCNTs produced sheet resistances in the range 4–24 Ω squ−1 with specular transparencies up to 82 %. Increasing the aqueous dispersibility of SWCNTs decreased the bundle size present in the film resulting in improved SWCNT surface dispersion in the films without compromising transparency or sheet resistance. In addition to providing conduction pathways between the AgNW network, the SWCNTs also provide structural support, creating stable self-supporting films. Entanglement of the AgNWs and SWCNTs was demonstrated to occur in solution prior to deposition by monitoring the transverse plasmon resonance mode of the AgNWs during processing. The interwoven AgNW/SWCNT structures show potential for use in optoelectronic applications as transparent electrodes and as an ITO replacement.

  20. Aligned nanowires and nanodots by directed block copolymer assembly

    International Nuclear Information System (INIS)

    The directed self-assembly of block copolymers (BCPs) is a promising route to generate highly ordered arrays of sub-10 nm features. Ultradense arrays of a monolayer of spherical microdomains or cylindrical microdomains oriented parallel to the surface have been produced where the lateral ordering is guided by surface patterning and the lattice defined by the patterning can be commensurate or incommensurate with the natural period of the BCP. Commensurability between the two can be used to elegantly manipulate the lateral ordering and orientation of the BCP microdomains so as to form well-aligned arrays of 1D nanowires or 2D addressable nanodots. No modification of the substrate surface, aside from the patterning, was used, making the influence of lattice mismatch and pattern amplification on the size, shape and pitch of the BCP microdomains more transparent. A skew angle between incommensurate lattices, defining a stretching or compression of the BCP chains to compensate for the lattice mismatch, is presented.

  1. Modelling hysteresis of interacting nanowires arrays

    International Nuclear Information System (INIS)

    Hysteresis loops of two-dimensional arrays of magnetic nanowires have been micromagnetically modelled. The calculations focus on magnetostatic interactions in addition to Zeeman and magnetic anisotropy energy terms. Starting from an ideally ordered hexagonal array, the generation of local disorder is first modelled and subsequently, hysteresis loops are calculated by Monte Carlo and iterative methods considering dipolar and higher-order multipole effects. The main conclusions of the modelling are: (i) distortion of the hexagonal ordering results in an increasing effective field to reach magnetic saturation while roughly maintaining coercivity, and (ii) an increase of the average distributed coercivity of individual nanowires gives rise to enhanced coercivity and anisotropy field. The results of these simulations are analysed in view of experimental loops of arrays of Ni nanowires filling nanoporous alumina membranes with different degrees of 2D-polycrystalline arrangement. After a careful analysis by image processing, it is concluded that fluctuations in the diameter and cross-section of individual nanowires play an important role in a deep correlation between modelled and experimental hysteresis loops

  2. Broadband Nonlinear Signal Processing in Silicon Nanowires

    DEFF Research Database (Denmark)

    Yvind, Kresten; Pu, Minhao; Hvam, Jørn Märcher;

    The fast non-linearity of silicon allows Tbit/s optical signal processing. By choosing suitable dimensions of silicon nanowires their dispersion can be tailored to ensure a high nonlinearity at power levels low enough to avoid significant two-photon abso We have fabricated low insertion...

  3. Fabricating nanoscale DNA patterns with gold nanowires.

    Science.gov (United States)

    Chen, Yulin; Kung, Sheng-Chin; Taggart, David K; Halpern, Aaron R; Penner, Reginald M; Corn, Robert M

    2010-04-15

    Surface patterns of single-stranded DNA (ssDNA) consisting of nanoscale lines as thin as 40 nm were fabricated on polymer substrates for nanotechnology and bioaffinity sensing applications. Large scale arrays (with areas up to 4 cm(2)) of ssDNA "nanolines" were created on streptavidin-coated polymer (PDMS) surfaces by transferring biotinylated ssDNA from a master pattern of gold nanowires attached to a glass substrate. The gold nano-wires were first formed on the glass substrate by the process of lithographically patterned nanowire electrodeposition (LPNE), and then "inked" with biotinylated ssDNA by hybridization adsorption to a thiol-modified ssDNA monolayer attached to the gold nanowires. The transferred ssDNA nanolines were capable of hybridizing with ssDNA from solution to form double-stranded DNA (dsDNA) patterns; a combination of fluorescence and atomic force microscopy (AFM) measurements were used to characterize the dsDNA nanoline arrays. To demonstrate the utility of these surfaces for biosensing, optical diffraction measurements of the hybridization adsorption of DNA-coated gold nanoparticles onto the ssDNA nanoline arrays were used to detect a specific target sequence of unlabeled ssDNA in solution. PMID:20337428

  4. Silicon nanowire field-effect chemical sensor

    NARCIS (Netherlands)

    Chen, Songyue

    2011-01-01

    This thesis describes the work that has been done on the project “Design and optimization of silicon nanowire for chemical sensing”, including Si-NW fabrication, electrical/electrochemical modeling, the application as ISFET, and the build-up of Si- NW/LOC system for automatic sample delivery. A nove

  5. Printing nanotube/nanowire for flexible microsystems

    Science.gov (United States)

    Tortorich, Ryan P.; Choi, Jin-Woo

    2014-04-01

    Printing has become an emerging manufacturing technology for mechanics, electronics, and consumer products. Additionally, both nanotubes and nanowires have recently been used as materials for sensors and electrodes due to their unique electrical and mechanical properties. Printed electrodes and conductive traces particularly offer versatility of fabricating low-cost, disposable, and flexible electrical devices and microsystems. While various printing methods such as screen printing have been conventional methods for printing conductive traces and electrodes, inkjet printing has recently attracted great attention due to its unique advantages including no template requirement, rapid printing at low cost, on-demand printing capability, and precise control of the printed material. Computer generated conductive traces or electrode patterns can simply be printed on a thin film substrate with proper conductive ink consisting of nanotubes or nanowires. However, in order to develop nanotube or nanowire ink, there are a few challenges that need to be addressed. The most difficult obstacle to overcome is that of nanotube/nanowire dispersion within a solution. Other challenges include adjusting surface tension and controlling viscosity of the ink as well as treating the surface of the printing substrate. In an attempt to pave the way for nanomaterial inkjet printing, we present a method for preparing carbon nanotube ink as well as its printing technique. A fully printed electrochemical sensor using inkjet-printed carbon nanotube electrodes is also demonstrated as an example of the possibilities for this technology.

  6. Optical Control of Electrons in Au Nanowires

    Science.gov (United States)

    Jones, Eric; Basnet, Gobind; Huang, Wayne; Flanders, Bret; Batelaan, Herman

    2016-05-01

    Gold nanowires, with diameters less than 100 nm, are novel sources for electron field emission. Their geometry confines the propagation of conduction electrons, giving rise to effects not seen in the bulk, such as ballistic currents and surface plasmon polaritons (SPPs). Dynamics within the wire are probed with laser-induced field emission from the nanowire tip. A balanced Mach-Zehnder interferometer is used to split and delay pulses up to 170 ps from a Ti:Saph oscillator (800 nm, 50 fs) in a pump-probe scheme. The output beamsplitter of the interferometer is mounted on a translation stage to control the separation of the pump and probe beams with sub-micron precision. The beams are focused to 3 μm spots on the tip and shaft of a nanowire, mounted under vacuum at 2 × 10-7 mTorr, by an off-axis parabolic mirror. Field-emitted electrons are counted by a channel electron multiplier. We discuss experimental results of our pump-probe experiments taken at different pump positions. Optical control of electron dynamics within these nanowires may lead to a truly on-demand source of single and multiple electron pulses. We gratefully acknowledge support from NSF awards 1306565 and 1430519.

  7. Ab initio vibrations in nonequilibrium nanowires

    DEFF Research Database (Denmark)

    Jauho, Antti-Pekka; Engelund, Mads; Markussen, T;

    2010-01-01

    We review recent results on electronic and thermal transport in two different quasi one-dimensional systems: Silicon nanowires (SiNW) and atomic gold chains. For SiNW's we compute the ballistic electronic and thermal transport properties on equal footing, allowing us to make quantitative...

  8. Fabrication of nanowires and conductance measurements

    Czech Academy of Sciences Publication Activity Database

    Nejo, H.; Fujita, D.; Odasso, S.; Rogers, D.; Slezák, Jiří

    Amsterdam: IOS Press, 2001 - (Allegrin, M.; Garcia, N.; Marti, O.), s. 331-350 [Internationa School of Physics "Eurico Fermi"/144./. Terst (IT), 00.00.2000] Institutional research plan: CEZ:AV0Z1010914 Keywords : nanowires * conductance measurements Subject RIV: BM - Solid Matter Physics ; Magnetism

  9. Bacterial streamers in curved microchannels

    Science.gov (United States)

    Rusconi, Roberto; Lecuyer, Sigolene; Guglielmini, Laura; Stone, Howard

    2009-11-01

    Biofilms, generally identified as microbial communities embedded in a self-produced matrix of extracellular polymeric substances, are involved in a wide variety of health-related problems ranging from implant-associated infections to disease transmissions and dental plaque. The usual picture of these bacterial films is that they grow and develop on surfaces. However, suspended biofilm structures, or streamers, have been found in natural environments (e.g., rivers, acid mines, hydrothermal hot springs) and are always suggested to stem from a turbulent flow. We report the formation of bacterial streamers in curved microfluidic channels. By using confocal laser microscopy we are able to directly image and characterize the spatial and temporal evolution of these filamentous structures. Such streamers, which always connect the inner corners of opposite sides of the channel, are always located in the middle plane. Numerical simulations of the flow provide evidences for an underlying hydrodynamic mechanism behind the formation of the streamers.

  10. Vimentin in Bacterial Infections

    DEFF Research Database (Denmark)

    Mak, Tim N; Brüggemann, Holger

    2016-01-01

    -vimentin interactions are presented in this review: the role of vimentin in pathogen-binding on the cell surface and subsequent bacterial invasion and the interaction of cytosolic vimentin and intracellular pathogens with regards to innate immune signaling. Mechanistic insight is presented involving distinct bacterial......Despite well-studied bacterial strategies to target actin to subvert the host cell cytoskeleton, thus promoting bacterial survival, replication, and dissemination, relatively little is known about the bacterial interaction with other components of the host cell cytoskeleton, including intermediate...... filaments (IFs). IFs have not only roles in maintaining the structural integrity of the cell, but they are also involved in many cellular processes including cell adhesion, immune signaling, and autophagy, processes that are important in the context of bacterial infections. Here, we summarize the knowledge...

  11. Fully solution-processed transparent electrodes based on silver nanowire composites for perovskite solar cells

    Science.gov (United States)

    Kim, Areum; Lee, Hongseuk; Kwon, Hyeok-Chan; Jung, Hyun Suk; Park, Nam-Gyu; Jeong, Sunho; Moon, Jooho

    2016-03-01

    We report all-solution-processed transparent conductive electrodes based on Ag nanowire (AgNW)-embedded metal oxide composite films for application in organometal halide perovskite solar cells. To address the thermal instability of Ag nanowires, we used combustive sol-gel derived thin films to construct ZnO/ITO/AgNW/ITO composite structures. The resulting composite configuration effectively prevented the AgNWs from undergoing undesirable side-reactions with halogen ions present in the perovskite precursor solutions that significantly deteriorate the optoelectrical properties of Ag nanowires in transparent conductive films. AgNW-based composite electrodes had a transmittance of ~80% at 550 nm and sheet resistance of 18 Ω sq-1. Perovskite solar cells fabricated using a fully solution-processed transparent conductive electrode, Au/spiro-OMeTAD/CH3NH3PbI3 + m-Al2O3/ZnO/ITO/AgNW/ITO, exhibited a power conversion efficiency of 8.44% (comparable to that of the FTO/glass-based counterpart at 10.81%) and were stable for 30 days in ambient air. Our results demonstrate the feasibility of using AgNWs as a transparent bottom electrode in perovskite solar cells produced by a fully printable process.We report all-solution-processed transparent conductive electrodes based on Ag nanowire (AgNW)-embedded metal oxide composite films for application in organometal halide perovskite solar cells. To address the thermal instability of Ag nanowires, we used combustive sol-gel derived thin films to construct ZnO/ITO/AgNW/ITO composite structures. The resulting composite configuration effectively prevented the AgNWs from undergoing undesirable side-reactions with halogen ions present in the perovskite precursor solutions that significantly deteriorate the optoelectrical properties of Ag nanowires in transparent conductive films. AgNW-based composite electrodes had a transmittance of ~80% at 550 nm and sheet resistance of 18 Ω sq-1. Perovskite solar cells fabricated using a fully solution

  12. Characterization of Co2FeAl nanowires

    Science.gov (United States)

    Sapkota, Keshab R.; Pegg, I. L.; Philip, J.

    2011-03-01

    Heusler alloy, Co 2 FeAl (CFA) is a potentially useful material in the field of spintronics due to its high spin polarization. The CFA nanowires are grown for the first time by the electrospinning method. The diameters of the wires formed are ranging from 80 -- 100 nm. The structural characterization of the nanowires is done using X-Ray diffraction and Raman spectroscopy. The nanowires exhibit cubic structure with a lattice constant, a = 2.44 Å. Parallel arrays of nanowires are grown for magnetic characterization using electric field applied at the collector plate. The nanowires exhibit ferromagnetic behavior with a Curie temperature higher than 400 K. Nanoscale devices are fabricated with single CFA nanowire to understand the magnetotransport properties. This work has been supported by funding from NSF under CAREER Grant No. ECCS-0845501 and NSF-MRI, DMR-0922997.

  13. Synthesis of SERS active Au nanowires in different noncoordinating solvents

    International Nuclear Information System (INIS)

    Au nanowires with length up to micrometers were synthesized through a simple and one-pot solution growth method. HAuCl4 was reduced in a micellar structure formed by 1-octadecylamine and oleic acid in hexane, heptane, toluene and chloroform, respectively. As the non-polarity of noncoordinating solvents can affect the nucleation and growth rates of Au nanostructures, Au nanowires with different diameters could be obtained by changing the noncoordinating solvents in the synthetic process. The influences of the solvents on the morphology of Au nanowires were systematically studied. When using hexane as reaction solvent, the product turned to be high portion of Au nanowires with more uniform size than the others. Furthermore, surface-enhanced Raman scattering (SERS) spectrum of 2-thionaphthol was obtained on the Au nanowire-modified substrate, indicating that the as-synthesized Au nanowires have potential for highly sensitive optical detection application.

  14. Tunnel junction enhanced nanowire ultraviolet light emitting diodes

    International Nuclear Information System (INIS)

    Polarization engineered interband tunnel junctions (TJs) are integrated in nanowire ultraviolet (UV) light emitting diodes (LEDs). A ∼6 V reduction in turn-on voltage is achieved by the integration of tunnel junction at the base of polarization doped nanowire UV LEDs. Moreover, efficient hole injection into the nanowire LEDs leads to suppressed efficiency droop in TJ integrated nanowire LEDs. The combination of both reduced bias voltage and increased hole injection increases the wall plug efficiency in these devices. More than 100 μW of UV emission at ∼310 nm is measured with external quantum efficiency in the range of 4–6 m%. The realization of tunnel junction within the nanowire LEDs opens a pathway towards the monolithic integration of cascaded multi-junction nanowire LEDs on silicon

  15. Electrochemical synthesis of core-shell magnetic nanowires

    Science.gov (United States)

    Ovejero, Jesús G.; Bran, Cristina; Vilanova, Enrique; Kosel, Jürgen; Morales, María P.; Vazquez, Manuel

    2015-09-01

    (Fe, Ni, CoFe) @ Au core-shell magnetic nanowires have been synthesized by optimized two-step potentiostatic electrodeposition inside self-assembled nanopores of anodic aluminium templates. The optimal electrochemical parameters (e.g., potential) have been firstly determined for the growth of continuous Au nanotubes at the inner wall of pores. Then, a magnetic core was synthesized inside the Au shells under suitable electrochemical conditions for a wide spectrum of single elements and alloy compositions (e.g., Fe, Ni and CoFe alloy). Novel opportunities offered by such nanowires are discussed particularly, the magnetic behavior of (Fe, Ni, CoFe) @ Au core-shell nanowires was tested and compared with that of bare nanowires. These core-shell nanowires can be released from the template thereby opening novel opportunities for biofunctionalization of individual nanowires.

  16. Capping of rare earth silicide nanowires on Si(001)

    International Nuclear Information System (INIS)

    The capping of Tb and Dy silicide nanowires grown on Si(001) was studied using scanning tunneling microscopy and cross-sectional high-resolution transmission electron microscopy. Several nanometers thick amorphous Si films deposited at room temperature allow an even capping, while the nanowires maintain their original structural properties. Subsequent recrystallization by thermal annealing leads to more compact nanowire structures and to troughs in the Si layer above the nanowires, which may even reach down to the nanowires in the case of thin Si films, as well as to V-shaped stacking faults forming along (111) lattice planes. This behavior is related to strain due to the lattice mismatch between the Si overlayer and the nanowires

  17. Multiple Silicon Nanowires with Enzymatic Modification for Measuring Glucose Concentration

    Directory of Open Access Journals (Sweden)

    Cheng-Chih Hsu

    2015-08-01

    Full Text Available This study fabricated a multiple poly-Si nanowires sensor through a top-down method and immobilized glucose oxidase on the multiple nanowires for determining glucose concentration. The proposed sensor is 340 nm in width and uses five physically identical and parallel nanowires. The sensor contained nanowires of various lengths (3, 5, and 10 μm. Experimental results showed that sensor sensitivity is inversely proportional to nanowire length. The sensor with 3 μm in nanowire length exhibited a theoretical resolution of 0.003 mg/dL and the highest sensitivity of 0.03 μA/(mg/dL. Furthermore, the proposed sensor retains this performance when reused for up to 10 applications.

  18. Synthetic Strategies and Applications of GaN Nanowires

    Directory of Open Access Journals (Sweden)

    Guoquan Suo

    2014-01-01

    Full Text Available GaN is an important III-V semiconductor material with a direct band gap of 3.4 eV at 300 K. The wide direct band gap makes GaN an attractive material for various applications. GaN nanowires have demonstrated significant potential as fundamental building blocks for nanoelectronic and nanophotonic devices and also offer substantial promise for integrated nanosystems. In this paper, we provide a comprehensive review on the general synthetic strategies, characterizations, and applications of GaN nanowires. We first summarize several growth techniques of GaN nanowires. Subsequently, we discuss mechanisms involved to generate GaN nanowires from different synthetic schemes and conditions. Then we review some characterization methods of GaN nanowires. Finally, several kinds of main applications of GaN nanowires are discussed.

  19. Controlled coupling of quantum dots to nanowire plasmons

    International Nuclear Information System (INIS)

    Full text: The diameter of dielectric waveguides is limited by the wavelength of the guided light. In contrast, gold and silver nanowires can sustain propagating plasmon modes even for significantly smaller dimensions. Furthermore the strong eld localization of the nanowire plasmon modes leads to a strong interaction with nearby quantum emitters such as quantum dots. We use electron beam lithography, rst, to fabricate silver nanowires and, second, to position a few dots close to one nanowire end in a template-assisted process. Scanning a focused laser spot over the nanowire ends, we demonstrate both, the excitation of nanowire modes by quantum dots and the addressing of the same dots by plasmons. We use the fluorescence signals to quantify the quantum dots/plasmon coupling and show that part of the plasmon-induced dot fluorescence couples back to plasmonic modes. (author)

  20. Capping of rare earth silicide nanowires on Si(001)

    Science.gov (United States)

    Appelfeller, Stephan; Franz, Martin; Kubicki, Milan; Reiß, Paul; Niermann, Tore; Schubert, Markus Andreas; Lehmann, Michael; Dähne, Mario

    2016-01-01

    The capping of Tb and Dy silicide nanowires grown on Si(001) was studied using scanning tunneling microscopy and cross-sectional high-resolution transmission electron microscopy. Several nanometers thick amorphous Si films deposited at room temperature allow an even capping, while the nanowires maintain their original structural properties. Subsequent recrystallization by thermal annealing leads to more compact nanowire structures and to troughs in the Si layer above the nanowires, which may even reach down to the nanowires in the case of thin Si films, as well as to V-shaped stacking faults forming along {111} lattice planes. This behavior is related to strain due to the lattice mismatch between the Si overlayer and the nanowires.