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Sample records for individual hollow nanoparticles

  1. Fabrication of Metallic Hollow Nanoparticles

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

    Metal and semiconductor nanoshells, particularly transition metal nanoshells, are fabricated using dendrimer molecules. Metallic colloids, metallic ions or semiconductors are attached to amine groups on the dendrimer surface in stabilized solution for the surface seeding method and the surface seedless method, respectively. Subsequently, the process is repeated with additional metallic ions or semiconductor, a stabilizer, and NaBH.sub.4 to increase the wall thickness of the metallic or semiconductor lining on the dendrimer surface. Metallic or semiconductor ions are automatically reduced on the metallic or semiconductor nanoparticles causing the formation of hollow metallic or semiconductor nanoparticles. The void size of the formed hollow nanoparticles depends on the dendrimer generation. The thickness of the metallic or semiconductor thin film around the dendrimer depends on the repetition times and the size of initial metallic or semiconductor seeds.

  2. Hollow nanoparticle cathode materials for sodium electrochemical cells and batteries

    DOEpatents

    Shevchenko, Elena; Rajh, Tijana; Johnson, Christopher S.; Koo, Bonil

    2016-07-12

    A cathode comprises, in its discharged state, a layer of hollow .gamma.-Fe.sub.2O.sub.3 nanoparticles disposed between two layers of carbon nanotubes, and preferably including a metallic current collector in contact with one of the layers of carbon nanotubes. Individual particles of the hollow .gamma.-Fe.sub.2O.sub.3 nanoparticles comprise a crystalline shell of .gamma.-Fe.sub.2O.sub.3 including cation vacancies within the crystal structure of the shell (i.e., iron vacancies of anywhere between 3% to 90%, and preferably 44 to 77% of available octahedral iron sites). Sodium ions are intercalated within at least some of the cation vacancies within the crystalline shell of the hollow .gamma.-Fe.sub.2O.sub.3 nanoparticles.

  3. Magnetic domains and surface effects in hollow maghemite nanoparticles

    SciTech Connect

    Cabot, Andreu; Alivisatos, A. Paul; Puntes, Victor; Balcells, Lluis; Iglesias, Oscar; Labarta, Amilcar

    2008-09-30

    In the present work, we investigate the magnetic properties of ferrimagnetic and non-interacting maghemite hollow nanoparticles obtained by the Kirkendall effect. From the experimental characterization of their magnetic behavior, we find that polycrystalline hollow maghemite nanoparticles exhibit low blocked-to-superparamagnetic transition temperatures, small magnetic moments, significant coercivities and irreversibility fields, and no magnetic saturation on external magnetic fields up to 5 T. These results are interpreted in terms of the microstructural parameters characterizing the maghemite shells by means of atomistic Monte Carlo simulations of an individual spherical shell. The model comprises strongly interacting crystallographic domains arranged in a spherical shell with random orientations and anisotropy axis. The Monte Carlo simulation allows discernment between the influence of the polycrystalline structure and its hollow geometry, while revealing the magnetic domain arranggement in the different temperataure regimes.

  4. Bioinspired hollow semiconductor nanospheres as photosynthetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Sun, Jianhua; Zhang, Jinshui; Zhang, Mingwen; Antonietti, Markus; Fu, Xianzhi; Wang, Xinchen

    2012-10-01

    Natural photosynthesis occurs in the thylakoid membrane where functional proteins and electron carriers are precisely arranged to efficiently convert sunlight into a chemical potential between the two membrane sides, via charge separation and electron transport chains, for use in oxygen generation and CO2 fixation. These light-harvesting complexes and cofactors have been actively mimicked using dyes, semiconductors and catalytic nanoparticles. However, the photosynthetic scaffold that optimizes both the capture and distribution of light and separates both the oxidative and reductive species has been mimicked much less often, especially using polymer substances. Here we report the synthesis of hollow nanospheres sized in the optical range and made of a robust semiconductor, melon or carbon-nitride polymer. These hollow nanospheres are shown to function as both light-harvesting antennae and nanostructured scaffolds that improve photoredox catalysis, which was determined to have a 7.5% apparent quantum yield via a hydrogen-generation assay.

  5. Ultrafast electronic energy redistribution in hollow gold nanoparticles.

    NASA Astrophysics Data System (ADS)

    Knappenberger, Kenneth; Schwartzberg, Adam

    2009-03-01

    Nanostructured materials offer great potential for novel ways to generate, utilize, store and transport energy. These unique opportunities arise because nanoclusters often portray strikingly different chemical and physical properties than their bulk counterparts, and, perhaps more intriguingly, these vary widely with cluster size and shape. Here we report on the redistribution of electronic energy to thermal phonons in a series of hollow gold nanoparticles using femtosecond transient absorption. Qualitatively, the relaxation processes are similar to those of solid nanoparticles, however distinct differences are observed, likely owing to the unique properties of the hollow structures. In particular, a larger excitation power density is required to observe coherent vibrational oscillations in hollow gold nanoparticles than is needed for solid particles following electronic excitation. This effect is systematically studied over a range of hollow and solid particles, including multiple diameters and wall thicknesses. Models will be presented to account for the different relaxation mechanism observed for hollow and solid gold nanoparticles.

  6. Oriented assembly of Fe3O4 nanoparticles into monodisperse hollow single-crystal microspheres.

    PubMed

    Yu, Dabin; Sun, Xiaoquan; Zou, Jiwei; Wang, Zirong; Wang, Feng; Tang, Kun

    2006-11-01

    Magnetite nanoparticles of Fe3O4 were found to assemble into monodisperse hollow Fe3O4 microspheres with tunable diameters ranging from 200 to 400 nm and open pores on the shells in ethylene glycol in the presence of dodecylamine (DDA). The oriented assembly of nanoparticles conferred the individual hollow Fe3O4 microspheres a remarkable feature of single crystals. The morphologies of the products could be easily manipulated by varying the synthesis parameters. Increasing the concentration of DDA led to an obvious shape evolution of the products from rhombic nanoparticles to hollow microspheres, solid microspheres, and finally irregular nanoparticles, which were mainly attributed to the special self-assembly phenomenon of Fe3O4 nanoparticles in the solvothermal process.

  7. Cobalt Oxide Hollow Nanoparticles Derived by Bio-Templating

    NASA Technical Reports Server (NTRS)

    Kim, Jae-Woo; Choi, Sang H.; Lillehei, Peter T.; Chu, Sang-Hyon; King, Glen C.; Watt, Gerald D.

    2005-01-01

    We present here the first fabrication of hollow cobalt oxide nanoparticles produced by a protein-regulated site-specific reconstitution process in aqueous solution and describe the metal growth mechanism in the ferritin interior.

  8. Biodegradable hollow silica nanospheres containing gold nanoparticle arrays.

    PubMed

    Cassano, Domenico; Rota Martir, Diego; Signore, Giovanni; Piazza, Vincenzo; Voliani, Valerio

    2015-06-21

    We introduce biodegradable hollow silica nanocapsules embedding arrays of 3 nm gold nanoparticles. The silica shell degrades in full serum in a few hours, potentially allowing the clearance of the capsules and their contents by the efficient renal pathway, and thereby overcoming accumulation issues typical of metal nanoparticles.

  9. Impurity-induced plasmon damping in individual cobalt-doped hollow Au nanoshells.

    PubMed

    Thibodeaux, Christyn A; Kulkarni, Vikram; Chang, Wei-Shun; Neumann, Oara; Cao, Yang; Brinson, Bruce; Ayala-Orozco, Ciceron; Chen, Chih-Wei; Morosan, Emilia; Link, Stephan; Nordlander, Peter; Halas, Naomi J

    2014-12-11

    The optical properties of plasmonic nanoparticles in the size range corresponding to the electrostatic, or dipole, limit have the potential to reveal effects otherwise masked by phase retardation. Here we examine the optical properties of individual, sub-50 nm hollow Au nanoshells (Co-HGNS), where Co is the initial sacrificial core nanoparticle, using single particle total internal reflection scattering (TIRS) spectroscopy. The residual Co present in the metallic shell induces a substantial broadening of the homogeneous plasmon resonance line width of the Co-HGNS, where the full width at half-maximum (fwhm) broadens proportionately with increasing Co content. This doping-induced line broadening provides a strategy for controlling plasmon line width independent of nanoparticle size, and has the potential to substantially modify the relative decay channels for localized nanoparticle surface plasmons. PMID:24921160

  10. Room-temperature Formation of Hollow Cu2O Nanoparticles

    SciTech Connect

    Hung, Ling-I; Tsung, Chia-Kuang; Huang, Wenyu; Yang, Peidong

    2010-01-18

    Monodisperse Cu and Cu2O nanoparticles (NPs) are synthesized using tetradecylphosphonic acid as a capping agent. Dispersing the NPs in chloroform and hexane at room temperature results in the formation of hollow Cu2O NPs and Cu@Cu2O core/shell NPs, respectively. The monodisperse Cu2O NPs are used to fabricate hybrid solar cells with efficiency of 0.14percent under AM 1.5 and 1 Sun illumination.

  11. A comparative study of hollow copper sulfide nanoparticles and hollow gold nanospheres on degradability and toxicity.

    PubMed

    Guo, Liangran; Panderi, Irene; Yan, Daisy D; Szulak, Kevin; Li, Yajuan; Chen, Yi-Tzai; Ma, Hang; Niesen, Daniel B; Seeram, Navindra; Ahmed, Aftab; Yan, Bingfang; Pantazatos, Dionysios; Lu, Wei

    2013-10-22

    Gold and copper nanoparticles have been widely investigated for photothermal therapy of cancer. However, degradability and toxicity of these nanoparticles remain concerns. Here, we compare hollow CuS nanoparticles (HCuSNPs) with hollow gold nanospheres (HAuNS) in similar particle sizes and morphology following intravenous administration to mice. The injected pegylated HCuSNPs (PEG-HCuSNPs) are eliminated through both hepatobiliary (67 percentage of injected dose, %ID) and renal (23 %ID) excretion within one month postinjection. By contrast, 3.98 %ID of Au is excreted from liver and kidney within one month after iv injection of pegylated HAuNS (PEG-HAuNS). Comparatively, PEG-HAuNS are almost nonmetabolizable, while PEG-HCuSNPs are considered biodegradable nanoparticles. PEG-HCuSNPs do not show significant toxicity by histological or blood chemistry analysis. Principal component analysis and 2-D peak distribution plots of data from matrix-assisted laser desorption ionization-time-of-flight imaging mass spectrometry (MALDI-TOF IMS) of liver tissues demonstrated a reversible change in the proteomic profile in mice receiving PEG-HCuSNPs. This is attributed to slow dissociation of Cu ion from CuS nanoparticles along with effective Cu elimination for maintaining homeostasis. Nonetheless, an irreversible change in the proteomic profile is observed in the liver from mice receiving PEG-HAuNS by analysis of MALDI-TOF IMS data, probably due to the nonmetabolizability of Au. This finding correlates with the elevated serum lactate dehydrogenase at 3 months after PEG-HAuNS injection, indicating potential long-term toxicity. The comparative results between the two types of nanoparticles will advance the development of HCuSNPs as a new class of biodegradable inorganic nanomaterials for photothermal therapy.

  12. Crystallization of hollow mesoporous silica nanoparticles.

    PubMed

    Drisko, Glenna L; Carretero-Genevrier, Adrian; Perrot, Alexandre; Gich, Martí; Gàzquez, Jaume; Rodriguez-Carvajal, Juan; Favre, Luc; Grosso, David; Boissière, Cédric; Sanchez, Clément

    2015-03-11

    Complex 3D macrostructured nanoparticles are transformed from amorphous silica into pure polycrystalline α-quartz using catalytic quantities of alkaline earth metals as devitrifying agent. Walls as thin as 10 nm could be crystallized without losing the architecture of the particles. The roles of cation size and the mol% of the incorporated devitrifying agent in crystallization behavior are studied, with Mg(2+), Ca(2+), Sr(2+) and Ba(2+) all producing pure α-quartz under certain conditions.

  13. Combinatorial approach to identify electronically cloaked hollow nanoparticles

    NASA Astrophysics Data System (ADS)

    Shen, Wenqing; Tian, Tao; Liao, Bolin; Zebarjadi, Mona

    2014-08-01

    The possibility of designing core-shell nanoparticles that are "invisible" to the conduction electrons has been demonstrated recently. A total scattering cross section smaller than 0.01% of the physical cross section was demonstrated by artificially adjusting the parameters of the barrier and the well in a core-shell geometry. In this paper, we aim to extend the developed concept and find realistic material combinations that satisfy the cloaking criteria. We report designs of hollow nanoparticles that could be used to realize the cloaking concept in III-V semiconductor host matrices. Such particles could be used in advanced materials design to enhance and tune the electrical and the thermoelectric properties of a given host matrix. This paper may also contribute to defect engineering by coating defect sites with a proper cloaking layer.

  14. Nanoparticle detection by mode splitting in hollow bottle microresonators

    NASA Astrophysics Data System (ADS)

    Chenari, Zeinab; Latifi, Hamid; Peysokhan, Mostafa

    2016-01-01

    Mode splitting (MS) in whispering gallery microresonators provides excellent noise suppression in sensing signal compared to mode shifting. Here, we theoretically studied the ability of hollow bottle microresonators for detection of a single nanoparticle in air and water medium by MS phenomenon. To find out the optimum condition of sensor for nanoparticle (NP) detection, the effects of bottle geometry parameters, mode orders, and mode polarization state was investigated. The first radial transverse electric mode demonstrated the best sensitivity when the resonator radius and wall thickness were 10 and 0.3 μm, respectively. However, transverse magnetic modes manifested slightly better detection limit. In the air core hollow microbottle resonator (HMBR), the best detection limit of 3.1 nm radius for polystyrene NPs was achieved at an optimum condition of 30-μm resonator radius and 0.8-μm wall thickness. While MS could not be resolved in deionized water filled HMBRs for all of the investigated conditions at 1550 nm, changing the wavelength to 780 nm provided a detection limit of 15.1 nm in water. Furthermore, it is found that the sensitivity of HMBR is increased by at least two times in comparison with a microtoroid sensor. HMBRs are optofluidic platforms, so employing them could drastically enhance the applicability of microresonator-based systems for label-free NP detection.

  15. Nanoparticle detection by mode splitting in hollow bottle microresonators

    NASA Astrophysics Data System (ADS)

    Chenari, Zeinab; Latifi, Hamid; Peysokhan, Mostafa

    2016-01-01

    Mode splitting (MS) in whispering gallery microresonators provides excellent noise suppression in sensing signal compared to mode shifting. Here, we theoretically studied the ability of hollow bottle microresonators for detection of a single nanoparticle in air and water medium by MS phenomenon. To find out the optimum condition of sensor for nanoparticle (NP) detection, the effects of bottle geometry parameters, mode orders, and mode polarization state was investigated. The first radial transverse electric mode demonstrated the best sensitivity when the resonator radius and wall thickness were 10 and 0.3 μm, respectively. However, transverse magnetic modes manifested slightly better detection limit. In the air core hollow microbottle resonator (HMBR), the best detection limit of 3.1 nm radius for polystyrene NPs was achieved at an optimum condition of 30-μm resonator radius and 0.8-μm wall thickness. While MS could not be resolved in deionized water filled HMBRs for all of the investigated conditions at 1550 nm, changing the wavelength to 780 nm provided a detection limit of 15.1 nm in water. Furthermore, it is found that the sensitivity of HMBR is increased by at least two times in comparison with a microtoroid sensor. HMBRs are optofluidic platforms, so employing them could drastically enhance the applicability of microresonator-based systems for label-free NP detection.

  16. Rapid degradation of azo dye methyl orange using hollow cobalt nanoparticles.

    PubMed

    Sha, Yingying; Mathew, Iswarya; Cui, Qingzhou; Clay, Molly; Gao, Fan; Zhang, Xiaoqi Jackie; Gu, Zhiyong

    2016-02-01

    A rapid and efficient method for methyl orange degradation using hollow cobalt (Co) nanoparticles is reported. Hollow Co nanoparticles were fabricated by a galvanic replacement reaction using aluminum (Al) nanoparticles as the template material. The methyl orange degradation characteristics were investigated by measuring the time dependent UV-Vis absorption of the dye solution, which showed a very fast degradation rate under acidic conditions. At an initial methyl orange concentration of 100 mg/L (pH = 2.5) and Co nanoparticle dosage of 0.5 g/L, the azo dye degradation efficiency reached up to 99% within 4 min, and the degradation constant rate was up to 2.444 min(-1), which is the highest value among other studies. A comparison of the decolorization rates at similar conditions with several other azo dyes, including Congo red, Amaranth, and Orange G, showed that the dye with a simpler structure and lower molecular mass decolorized considerably faster than the ones having a more complicated structure (higher molecular mass). The methyl orange degradation was also conducted using hollow nickel (Ni) nanoparticles and commercially available solid spherical Co and Ni nanoparticles. The results showed that Co-based nanoparticles outperformed Ni-based nanoparticles, with the hollow Co nanoparticles exhibiting the fastest degradation rate. Using the hollow Co nanoparticles is a very promising approach for the remediation of methyl orange dye containing wastewater due to the fast degradation rate and high degradation efficiency. In addition, these hollow Co nanoparticles are easily recycled because of their magnetic property. PMID:26498101

  17. Rapid degradation of azo dye methyl orange using hollow cobalt nanoparticles.

    PubMed

    Sha, Yingying; Mathew, Iswarya; Cui, Qingzhou; Clay, Molly; Gao, Fan; Zhang, Xiaoqi Jackie; Gu, Zhiyong

    2016-02-01

    A rapid and efficient method for methyl orange degradation using hollow cobalt (Co) nanoparticles is reported. Hollow Co nanoparticles were fabricated by a galvanic replacement reaction using aluminum (Al) nanoparticles as the template material. The methyl orange degradation characteristics were investigated by measuring the time dependent UV-Vis absorption of the dye solution, which showed a very fast degradation rate under acidic conditions. At an initial methyl orange concentration of 100 mg/L (pH = 2.5) and Co nanoparticle dosage of 0.5 g/L, the azo dye degradation efficiency reached up to 99% within 4 min, and the degradation constant rate was up to 2.444 min(-1), which is the highest value among other studies. A comparison of the decolorization rates at similar conditions with several other azo dyes, including Congo red, Amaranth, and Orange G, showed that the dye with a simpler structure and lower molecular mass decolorized considerably faster than the ones having a more complicated structure (higher molecular mass). The methyl orange degradation was also conducted using hollow nickel (Ni) nanoparticles and commercially available solid spherical Co and Ni nanoparticles. The results showed that Co-based nanoparticles outperformed Ni-based nanoparticles, with the hollow Co nanoparticles exhibiting the fastest degradation rate. Using the hollow Co nanoparticles is a very promising approach for the remediation of methyl orange dye containing wastewater due to the fast degradation rate and high degradation efficiency. In addition, these hollow Co nanoparticles are easily recycled because of their magnetic property.

  18. Bubble template synthesis of hollow gold nanoparticles and their applications as theranostic agents

    NASA Astrophysics Data System (ADS)

    Huang, Chienwen

    Hollow gold nanoparticle with a sub-30nm polycrystalline shell and a 50 nm hollow core has been successfully synthesized through the reduction of sodium gold sulfite by electrochemically evolved hydrogen. Such hollow gold nanoparticles exhibit unique plasmonic properties. They strongly scatter and absorb near infrared light. In this thesis we seek to understand the formation mechanism of hollow gold nanoparticles in this new synthesis process and their plasmonic properties. Also, we explore their biomedical applications as theranostic agents (therapeutic and diagnostic imaging). A lithographically patterned electrode consisting of Ag stripes on a glass substrate was used to investigate the formation process of hollow gold nanoparticles. Ag stripes served as working electrode for electrochemically evolution of hydrogen, and adjacent glass areas provided supporting surface for hydrogen nanobubbles nucleation and growth. Hydrogen nanobubbles served as both templates and reducing agents to trigger the autocatalytic disproportionation reaction of sodium gold sulfite. The effects of applied potential and the additives in the electrolyte have been studied. It has been found that the size and size distribution of hollow gold nanoparticle are directly relative to the applied potential, i.e. the hydrogen evolution rate. It has also been found the addition of Ni2+ ions can greatly improve the size distribution of hollow gold nanoparticles that can be contributed to that the newly electrodeposited nickel metal can enhance the hydrogen evolution efficiency. Another additive, ethylenediamine (EDA) can suppress the autocatalytic reaction of gold sulfite to increase the stability of sodium gold sulfite electrolyte. To capture such electrochemically evolved hydrogen nanobubbles, and subsequently to generate hollow gold nanoparticles in large numbers, alumina membranes were placed on the top of the working electrode. Anodic alumina membrane consists of ~200 nm pores, which provides

  19. Surfactant-free synthesis of mesoporous and hollow silica nanoparticles with an inorganic template.

    PubMed

    Baù, Luca; Bártová, Barbora; Arduini, Maria; Mancin, Fabrizio

    2009-12-28

    A surfactant-free synthesis of mesoporous and hollow silica nanoparticles is reported in which boron acts as the templating agent. Using such a simple and mild procedure as a treatment with water, the boron-rich phase is selectively removed, affording mesoporous pure silica nanoparticles with wormhole-like pores or, depending on the synthetic conditions, silica nanoshells.

  20. Evaporation induced self-assembly of nanoparticles in realizing hollow microcapsules

    NASA Astrophysics Data System (ADS)

    Sen, D.; Bahadur, J.; Mazumder, S.

    2012-06-01

    Hollow spherical microcapsules are realized using evaporation induced self assembly of silica nanoparticles by spray drying method. Nanoparticles in spray droplets get jammed, during water evaporation, in an anisotropic fashion, at droplet air-water interface by the action of attractive capillary force. Two levels of structural hierarchy of the microcapsules are investigated using small-angle neutron scattering and scanning electron microscopy.

  1. Nanostructural transformations during the reduction of hollow and porous nickel oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Medford, John A.; Johnston-Peck, Aaron C.; Tracy, Joseph B.

    2012-12-01

    Size-dependent nanostructural transformations occurring during the H2-mediated reduction of hollow and porous NiO nanoparticles were investigated for controlled nanoparticle sizes of ~10 to 100 nm. Transmission electron microscopy reveals that the location and number of reduction sites strongly depend on the nanoparticle size and structure.Size-dependent nanostructural transformations occurring during the H2-mediated reduction of hollow and porous NiO nanoparticles were investigated for controlled nanoparticle sizes of ~10 to 100 nm. Transmission electron microscopy reveals that the location and number of reduction sites strongly depend on the nanoparticle size and structure. Electronic supplementary information (ESI) available: Additional TEM images, SAED, and HRTEM images without color overlays. See DOI: 10.1039/c2nr33005a

  2. Hollow hybrid polymer-graphene oxide nanoparticles via Pickering miniemulsion polymerization.

    PubMed

    Thickett, Stuart C; Wood, Noriko; Ng, Yun Hau; Zetterlund, Per B

    2014-08-01

    The preparation of hybrid hollow capsules consisting of a cross-linked polymer shell and a coating of graphene oxide (GO) is demonstrated. The capsules are prepared by Pickering miniemulsion polymerization, exploiting the surface activity of GO for its use as a colloidal surfactant. This approach represents a simple and convenient route towards hollow carbon nanostructures for a variety of applications. The incorporation of surface-modified TiO2 nanoparticles into the interior of these capsules was also demonstrated. PMID:24976455

  3. Synthesis and characterization of spherical hollow composed of Cu 2S nanoparticles

    NASA Astrophysics Data System (ADS)

    Yang, Ming; Yang, Xiao; Huai, Lufeng; Liu, Wei

    2008-12-01

    Hollow spheres of Cu 2S nanoparticles with an average diameter of 200-400 nm have been prepared by thermal decomposition of CuSCN spheres at 450 °C and reaction with aqueous ammonia. The products were characterized by powder X-ray diffraction, transmission electron microscopy and UV-vis absorption spectroscopy. The band gap is estimated to be 2.96 eV according to the results of optical measurements of the hollow spheres of Cu 2S nanoparticles.

  4. Diverse melting modes and structural collapse of hollow bimetallic core-shell nanoparticles: a perspective from molecular dynamics simulations.

    PubMed

    Huang, Rao; Shao, Gui-Fang; Zeng, Xiang-Ming; Wen, Yu-Hua

    2014-11-14

    Introducing hollow structures into metallic nanoparticles has become a promising route to improve their catalytic performances. A fundamental understanding of thermal stability of these novel nanostructures is of significance for their syntheses and applications. In this article, molecular dynamics simulations have been employed to offer insights into the thermodynamic evolution of hollow bimetallic core-shell nanoparticles. Our investigation reveals that for hollow Pt-core/Au-shell nanoparticle, premelting originates at the exterior surface, and a typical two-stage melting behavior is exhibited, similar to the solid ones. However, since the interior surface provides facilitation for the premelting initiating at the core, the two-stage melting is also observed in hollow Au-core/Pt-shell nanoparticle, remarkably different from the solid one. Furthermore, the collapse of hollow structure is accompanied with the overall melting of the hollow Pt-core/Au-shell nanoparticle while it occurs prior to that of the hollow Au-core/Pt-shell nanoparticle and leads to the formation of a liquid-core/solid-shell structure, although both of them finally transform into a mixing alloy with Au-dominated surface. Additionally, the existence of stacking faults in the hollow Pt-core/Au-shell nanoparticle distinctly lowers its melting point. This study could be of great importance to the design and development of novel nanocatalysts with both high activity and excellent stability.

  5. Diverse Melting Modes and Structural Collapse of Hollow Bimetallic Core-Shell Nanoparticles: A Perspective from Molecular Dynamics Simulations

    PubMed Central

    Huang, Rao; Shao, Gui-Fang; Zeng, Xiang-Ming; Wen, Yu-Hua

    2014-01-01

    Introducing hollow structures into metallic nanoparticles has become a promising route to improve their catalytic performances. A fundamental understanding of thermal stability of these novel nanostructures is of significance for their syntheses and applications. In this article, molecular dynamics simulations have been employed to offer insights into the thermodynamic evolution of hollow bimetallic core-shell nanoparticles. Our investigation reveals that for hollow Pt-core/Au-shell nanoparticle, premelting originates at the exterior surface, and a typical two-stage melting behavior is exhibited, similar to the solid ones. However, since the interior surface provides facilitation for the premelting initiating at the core, the two-stage melting is also observed in hollow Au-core/Pt-shell nanoparticle, remarkably different from the solid one. Furthermore, the collapse of hollow structure is accompanied with the overall melting of the hollow Pt-core/Au-shell nanoparticle while it occurs prior to that of the hollow Au-core/Pt-shell nanoparticle and leads to the formation of a liquid-core/solid-shell structure, although both of them finally transform into a mixing alloy with Au-dominated surface. Additionally, the existence of stacking faults in the hollow Pt-core/Au-shell nanoparticle distinctly lowers its melting point. This study could be of great importance to the design and development of novel nanocatalysts with both high activity and excellent stability. PMID:25394424

  6. Sonochemical Synthesis and Magnetic Imaging of Hollow-Shell Iron-Platinum Nanoparticles

    NASA Astrophysics Data System (ADS)

    Baker, Remmi; Barnes, Paris; Martell, Eric

    2015-04-01

    As science has continued to evolve, scientists have been diving deeper and deeper, researching and analyzing the tiniest of objects. Interestingly, materials such as gold, silver, iron, and platinum behave differently on the nanoscale than the macroscale. Discrepancies between the behaviors of macro- and nanoparticles of the same substance are not well understood, which has led scientists to pursue the question as to why nanoparticles behave differently. Further research into the fabrication of hollow-shell iron-platinum nanoparticles and their unique properties may lead to real-world applications. Iron-platinum (FePt) nanoparticles are recognized for their unique magnetic properties; however, these properties have largely not been researched. FePt samples were prepared using sonochemical techniques. We report on the magnetic force microscopy imaging for self-assembled hollow-shell FePt nanoparticles, and relate our findings to the physical characteristics of the hollow-shell FePt nanoparticles. Additionally, we investigate the magnetic properties for FePt nanoparticles by analyzing the role of the electrons and their interactions occurring within the magnetic domain.

  7. Capillary-force-induced formation of luminescent polystyrene/(rare-earth-doped nanoparticle) hybrid hollow spheres.

    PubMed

    Chen, Min; Xie, Lin; Li, Fuyou; Zhou, Shuxue; Wu, Limin

    2010-10-01

    This paper presents a "one-pot" procedure to synthesize polystyrene/(rare-earth-doped nanoparticles) (PS/REDNPs) hybrid hollow spheres via the in situ diffusion of organic core into inorganic shell under strong capillary force. In this approach, when carboxyl-capped PS colloids were deposited by different REDNPs in aqueous medium, such as LaF3:Eu3+, LaF3:Ce3+-Tb3+, and YVO4:Dy3+, PS/REDNPs inorganic-organic hybrid hollow spheres could be directly obtained via the in situ diffusion of core PS chains into the voids between rare-earth-doped nanoparticles through the strong capillary force. Not only is the synthetic procedure versatile and very simple, but also the obtained hybrid hollow spheres are hydrophilic and luminescent and could be directly used in chemical and biological fields.

  8. Hollow polymer nanoparticles with S-nitrosothiols as scaffolds for nitric oxide release.

    PubMed

    Liu, Tuanwei; Zhang, Wei; Yang, Xinlin; Li, Chenxi

    2015-12-01

    This work reported the design, preparation and characterization of functional hollow polymer nanoparticles with S-nitrosothiol (SNO) as scaffolds for nitric oxide (NO) release in PBS buffer and bovine serum. The thiolated hollow polymer nanoparticles were prepared by distillation precipitation polymerization of ethyleneglycol dimethacrylate (EGDMA) and 2-hydroxyethyl methacrylate (HEMA) in presence of 3-(methacryloxy)propyltrimethoxysilane (MPS)-modified silica as seeds and the selective removal of silica core in hydrofluoric acid (HF) aqueous solution together with the subsequent surface esterification of hydroxyl groups with acryloyl chloride to introduce high density of vinyl groups and further Michael addition of carbon-carbon double bonds with hydrosulfide (HS(-)) anions. S-Nitrosothiol (SNO) functionalized hollow polymer nanoparticles were prepared via nitrosation of the surface thiol groups with acidified nitrite. The releasing characters of SNO-functionalized hollow polymer nanoparticles as NO scaffolds with capacity of 1.55 μmol/mg were investigated in different media, including PBS buffer exposure to trace copper cations and in real bovine serum. PMID:26275504

  9. Hollow Inorganic Nanoparticles as Efficient Carriers for siRNA Delivery: A Comprehensive Review.

    PubMed

    Varshosaz, Jaleh; Taymouri, Somayeh

    2015-01-01

    Small interfering RNAs (siRNA) are emerging as a new opportunity for treatment of various diseases, including viral and cancer diseases via knocking down a specific gene that involves in disease development. But their clinical application is hampered because of susceptibility to degradation and difficult delivery of siRNA into cells. So it is needed to develop an efficient carrier that stabilizes and delivers siRNA efficiently and specifically into cells. Hollow inorganic nanoparticles have gained considerable attention as an efficient drug and gene delivery system. This is due to their biocompatibility, simple preparative processes, easy functionalization and high capacity for drug loading. Several nanoparticle platforms for siRNA delivery have been developed to overcome the major limitations facing the therapeutic uses of siRNA. Recently, researchers have developed a wide range of inorganic nanocarriers to increase efficacy of si-RNA-based drugs and gained efficient siRNA delivery both in vitro and in vivo. This review covers a broad spectrum of hollow inorganic nanoparticles as non-viral siRNA delivery systems. These nanoparticles are developed for enhanced cellular uptake and targeted gene silencing in vitro and in vivo and their characteristics and opportunities for clinical applications of therapeutic siRNA are discussed in this article. Various types of inorganic hollow nanovectors including: mesoporous silica nanoparticles, carbon nanotubes, graphene oxide, fullerenes, calcium phosphate nanoparticles, hollow manganese oxide, gold nanoshells, and layered double hydroxide nanoparticles used to deliver siRNA are introduced and the development of theranostics and combinational treatment is also discussed. PMID:26323421

  10. PdNi hollow nanoparticles for improved electrocatalytic oxygen reduction in alkaline environments.

    PubMed

    Wang, Meng; Zhang, Weimin; Wang, Jiazhao; Wexler, David; Poynton, Simon D; Slade, Robert C T; Liu, Huakun; Winther-Jensen, Bjorn; Kerr, Robert; Shi, Dongqi; Chen, Jun

    2013-12-11

    Palladium-nickel (PdNi) hollow nanoparticles were synthesized via a modified galvanic replacement method using Ni nanoparticles as sacrificial templates in an aqueous medium. X-ray diffraction and transmission electron microscopy show that the as-synthesized nanoparticles are alloyed nanostructures and have hollow interiors with an average particle size of 30 nm and shell thickness of 5 nm. Compared with the commercially available Pt/C or Pd/C catalysts, the synthesized PdNi/C has superior electrocatalytic performance towards the oxygen reduction reaction, which makes it a promising electrocatalyst for alkaline anion exchange membrane fuel cells and alkali-based air-batteries. The electrocatalyst is finally examined in a H2/O2 alkaline anion exchange membrane fuel cell; the results show that such electrocatalysts could work in a real fuel cell application as a more efficient catalyst than state-of-the-art commercially available Pt/C. PMID:24199836

  11. Characteristics of a toroidal planar hollow cathode and its use for the preparation of Bi nanoparticles

    NASA Astrophysics Data System (ADS)

    Perez, A.; Luna, A. T.; Muhl, S.

    2013-12-01

    Using ideas from the sputter deposition by gas flow hollow cathode (GFHC) we have designed a new version in the form of a toroidal planar hollow cathode. Here the flow of gas is used to entrain the sputtered atoms and nanoparticles formed by agglomeration in the gas phase, through the cathode central exit aperture towards the substrate. We have studied the characteristics of the deposit as a function of the applied pulsed dc electrical power, the argon gas pressure and flow. By varying the different operating parameters, such as pressure (6.7-267 Pa), power (40-120 W) and gas flow (20-140 sccm), it was possible to control the size of the nanoparticles (10-150 nm) and the deposition rate (0.4-4.0 nm min-1). We demonstrate that the nanoparticles are of crystalline bismuth, even though the cathode is made of graphite with small added pieces of bismuth.

  12. Solvothermal synthesis of superhydrophobic hollow carbon nanoparticles from a fluorinated alcohol

    NASA Astrophysics Data System (ADS)

    Lyth, S. M.; Ma, W.; Liu, J.; Daio, T.; Sasaki, K.; Takahara, A.; Ameduri, B.

    2015-09-01

    A new and simple method of synthesizing fluorinated carbon at the gram scale is presented by reacting a fluorinated alcohol with sodium at elevated temperatures in a sealed Teflon reactor. The resulting carbon nanoparticles are around 100 nm in diameter, and display a hollow shell morphology, with a significant amount of fluorine doped into the carbon. The nanoparticles disperse easily in ethanol, and are thermally stable up to 400 °C and 450 °C under air and nitrogen, respectively. The nanoparticle dispersion was printed onto various substrates (paper, cloth, silicon), inducing superhydrophobicity.

  13. Hollow Block Copolymer Nanoparticles through a Spontaneous One-Step Structural Reorganization

    PubMed Central

    Petzetakis, Nikos; Robin, Mathew P.; Patterson, Joseph P.; Kelley, Elizabeth G.; Cotanda, Pepa; Bomans, Paul H. H.; Sommerdijk, Nico A. J. M.; Dove, Andrew P.; Epps, Thomas H.; O'Reilly, Rachel K.

    2013-01-01

    The spontaneous one-step synthesis of hollow nanocages and nanotubes from spherical and cylindrical micelles based on poly(acrylic acid)-b-polylactide (P(AA)-b-P(LA)) block copolymers (BCPs) has been achieved. This structural reorganization, which occurs simply upon drying of the samples, was elucidated by transmission electron microscopy (TEM) and atomic force microscopy (AFM). We show that it was necessary to use stain-free imaging to examine these nanoscale assemblies, as the hollow nature of the particles was obscured by application of a heavy metal stain. Additionally, the internal topology of the P(AA)-b-P(LA) particles could be tuned by manipulating the drying conditions to give solid or compartmentalized structures. Upon re-suspension, these reorganized nanoparticles retain their hollow structure and can be display significantly enhanced loading of a hydrophobic dye compared to the original cylinders. PMID:23391297

  14. Synthetically programmable nanoparticle superlattices using a hollow three-dimensional spacer approach

    SciTech Connect

    Auyeung, Evelyn; Cutler, Joshua I.; Macfarlane, Robert J.; Jones, Matthew R.; Wu, Jinsong; Liu, George; Zhang, Ke; Osberg, Kyle D.; Mirkin, Chad A.

    2013-04-08

    Crystalline nanoparticle arrays and superlattices with well-defined geometries can be synthesized by using appropriate electrostatic, hydrogen-bonding or biological recognition interactions. Although superlattices with many distinct geometries can be produced using these approaches, the library of achievable lattices could be increased by developing a strategy that allows some of the nanoparticles within a binary lattice to be replaced with 'spacer' entities that are constructed to mimic the behaviour of the nanoparticles they replace, even though they do not contain an inorganic core. The inclusion of these spacer entities within a known binary superlattice would effectively delete one set of nanoparticles without affecting the positions of the other set. Here, we show how hollow DNA nanostructures can be used as 'three-dimensional spacers' within nanoparticle superlattices assembled through programmable DNA interactions. We show that this strategy can be used to form superlattices with five distinct symmetries, including one that has never before been observed in any crystalline material.

  15. Xanthoceraside hollow gold nanoparticles, green pharmaceutics preparation for poorly water-soluble natural anti-AD medicine.

    PubMed

    Meng, Da-Li; Shang, Lei; Feng, Xiao-He; Huang, Xing-Fei; Che, Xin

    2016-06-15

    In order to increase the solubility of poorly water-soluble natural product, xanthoceraside, an effective anti-AD compound from Xanthoceras sorbifolia Bunge, and maintain its natural property, the xanthoceraside hollow gold nanoparticles were successively prepared by green ultrasonic method with silica spheres as templates and HF solution as selective etching solvent. Hollow gold nanoparticles and drug-loaded hollow gold nanoparticles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The solubilities of xanthoceraside loaded on hollow gold nanoparticles were increased obviously from 3.0μg/ml and 2.5μg/ml to 12.7μg/ml and 10.7μg/ml at 25°C and 37°C, respectively. The results of XRD and DSC indicated that the reason for this increase was mainly due to the amorphous state of xanthoceraside loaded on the hollow gold nanoparticles. In summary, the method of loading xanthoceraside onto hollow gold nanoparticles was a green and useful strategy to improve the solubility and dissolution of poorly water-soluble natural products and worth to applying to other natural products.

  16. Synthesis and Modeling of Hollow Intermetallic Ni-Zn Nanoparticles Formed by the Kirkendall Effect

    SciTech Connect

    Jana, Subhra; Chang, Ji Woong; Rioux, Robert M.

    2013-10-09

    Intermetallic Ni–Zn nanoparticles (NPs) were synthesized via the chemical conversion of nickel NPs using a zerovalent organometallic zinc precursor. After the injection of a diethylzinc solution, Ni NPs progressively transformed from a solid to a hollow Ni–Zn intermetallic structure with time. During the transformation of Ni NPs to intermetallic structures, they retained their overall spherical morphology. The growth mechanism for the solid-to-hollow nanoparticle transformation is ascribed to the nanoscale Kirkendall effect due to unequal diffusion rates of Ni and Zn. We develop a diffusion model for nonreactive, homogeneous, diffusion-controlled intermetallic hollow NP formation including moving boundaries at the interfaces of void–solid and solid–bulk solutions. Apparent diffusion coefficients for both metals and vacancy were evaluated from modeling the time-dependent growth of the void. The apparent diffusion coefficients obtained in this system compared favorably with results from measurement at grain boundaries in bulk Ni–Zn. This study represents the first combined experimental modeling of the formation of hollow nanostructures by the nanoscale Kirkendall effect.

  17. Hollow silicon carbide nanoparticles from a non-thermal plasma process

    NASA Astrophysics Data System (ADS)

    Coleman, Devin; Lopez, Thomas; Yasar-Inceoglu, Ozgul; Mangolini, Lorenzo

    2015-05-01

    We demonstrate the synthesis of hollow silicon carbide nanoparticles via a two-step process involving the non-thermal plasma synthesis of silicon nanoparticles, followed by their in-flight carbonization, also initiated by a non-thermal plasma. Simple geometric considerations associated with the expansion of the silicon lattice upon carbonization, in combination of the spherical geometry of the system, explain the formation of hollow nanostructures. This is in contrast with previous reports that justify the formation of hollow particles by means of out-diffusion of the core element, i.e., by the Kirkendall nanoscale effect. A theoretical analysis of the diffusion kinetics indicates that interaction with the ionized gas induces significant nanoparticle heating, allowing for the fast transport of carbon into the silicon particle and for the subsequent nucleation of the beta-silicon carbide phase. This work confirms the potential of non-thermal plasma processes for the synthesis of nanostructures composed of high-melting point materials, and suggests that such processes can be tuned to achieve morphological control.

  18. Combinatorial photothermal and immuno cancer therapy using chitosan-coated hollow copper sulfide nanoparticles.

    PubMed

    Guo, Liangran; Yan, Daisy D; Yang, Dongfang; Li, Yajuan; Wang, Xiaodong; Zalewski, Olivia; Yan, Bingfang; Lu, Wei

    2014-06-24

    Near-infrared light-responsive inorganic nanoparticles have been shown to enhance the efficacy of cancer photothermal ablation therapy. However, current nanoparticle-mediated photothermal ablation is more effective in treating local cancer at the primary site than metastatic cancer. Here, we report the design of a near-infrared light-induced transformative nanoparticle platform that combines photothermal ablation with immunotherapy. The design is based on chitosan-coated hollow CuS nanoparticles that assemble the immunoadjuvants oligodeoxynucleotides containing the cytosine-guanine (CpG) motifs. Interestingly, these structures break down after laser excitation, reassemble, and transform into polymer complexes that improve tumor retention of the immunotherapy. In this "photothermal immunotherapy" approach, photothermal ablation-induced tumor cell death reduces tumor growth and releases tumor antigens into the surrounding milieu, while the immunoadjuvants potentiate host antitumor immunity. Our results indicated that combined photothermal immunotherapy is more effective than either immunotherapy or photothermal therapy alone against primary treated and distant untreated tumors in a mouse breast cancer model. These hollow CuS nanoparticles are biodegradable and can be eliminated from the body after laser excitation.

  19. Combinatorial Photothermal and Immuno Cancer Therapy Using Chitosan-Coated Hollow Copper Sulfide Nanoparticles

    PubMed Central

    2015-01-01

    Near-infrared light-responsive inorganic nanoparticles have been shown to enhance the efficacy of cancer photothermal ablation therapy. However, current nanoparticle-mediated photothermal ablation is more effective in treating local cancer at the primary site than metastatic cancer. Here, we report the design of a near-infrared light-induced transformative nanoparticle platform that combines photothermal ablation with immunotherapy. The design is based on chitosan-coated hollow CuS nanoparticles that assemble the immunoadjuvants oligodeoxynucleotides containing the cytosine-guanine (CpG) motifs. Interestingly, these structures break down after laser excitation, reassemble, and transform into polymer complexes that improve tumor retention of the immunotherapy. In this “photothermal immunotherapy” approach, photothermal ablation-induced tumor cell death reduces tumor growth and releases tumor antigens into the surrounding milieu, while the immunoadjuvants potentiate host antitumor immunity. Our results indicated that combined photothermal immunotherapy is more effective than either immunotherapy or photothermal therapy alone against primary treated and distant untreated tumors in a mouse breast cancer model. These hollow CuS nanoparticles are biodegradable and can be eliminated from the body after laser excitation. PMID:24801008

  20. Au and Ag/Au double-shells hollow nanoparticles with improved near infrared surface plasmon and photoluminescence properties.

    PubMed

    Ghosh Chaudhuri, Rajib; Paria, Santanu

    2016-01-01

    Metallic hollow nanoparticles have been continuously drawing researcher's attention because of their excellent improved performance compare to the spherical particles in catalysis, photonics, information storage, surface-enhanced Raman scattering, and sensors applications. In this article we demonstrate a novel route for the synthesis of single and double-shells Au and Ag/Au bimetallic hollow nanoparticles using elemental sulfur as a sacrificial core. We also investigate the optical properties of these new hollow particles and compare with that of pure spherical nanoparticles. The surface plasmon resonance spectra of solid Au, hollow single shell Au, and double shells Ag/Au nanoparticles show that there is gradual shifting of Au peak position towards the higher wavelengths for these three nanoparticles respectively. A similar observation was also found for photoluminescence spectra. In case of double-shells Ag/Au hollow nanoparticles the emission spectrum shifts towards the NIR region with significant higher intensity, which is beneficial for in vivo biomedical applications of these particles.

  1. Phase-change material filled hollow magnetic nanoparticles for cancer therapy and dual modal bioimaging

    NASA Astrophysics Data System (ADS)

    Li, Jinghua; Hu, Yan; Hou, Yanhua; Shen, Xinkun; Xu, Gaoqiang; Dai, Liangliang; Zhou, Jun; Liu, Yun; Cai, Kaiyong

    2015-05-01

    To develop carriers for anti-cancer drug delivery, this study reports a biocompatible and thermal responsive controlled drug delivery system based on hollow magnetic nanoparticles (HMNPs). The system is constructed simply by filling the hollow interiors of HMNPs with a phase-change material (PCM), namely, 1-tetradecanol, which has a melting point of 38 °C. The system achieves near ``zero release'' of both hydrophobic paclitaxel (PTX) and hydrophilic doxorubicin hydrochloride (DOX) and precise ``on'' or ``off'' drug delivery in vitro to efficiently induce cell apoptosis. Furthermore, the system displays both infrared thermal imaging and magnetic resonance imaging properties. More importantly, the system demonstrates great potential for thermo-chemo combination cancer therapy in vivo when an alternating magnetic field is applied.To develop carriers for anti-cancer drug delivery, this study reports a biocompatible and thermal responsive controlled drug delivery system based on hollow magnetic nanoparticles (HMNPs). The system is constructed simply by filling the hollow interiors of HMNPs with a phase-change material (PCM), namely, 1-tetradecanol, which has a melting point of 38 °C. The system achieves near ``zero release'' of both hydrophobic paclitaxel (PTX) and hydrophilic doxorubicin hydrochloride (DOX) and precise ``on'' or ``off'' drug delivery in vitro to efficiently induce cell apoptosis. Furthermore, the system displays both infrared thermal imaging and magnetic resonance imaging properties. More importantly, the system demonstrates great potential for thermo-chemo combination cancer therapy in vivo when an alternating magnetic field is applied. Electronic supplementary information (ESI) available: TEM images and particle size distribution, XRD patterns of different nanoparticles, trypan blue staining, cell uptake (TEM imges), TUNEL staining, elemental analysis, zeta-potential measurements. See DOI: 10.1039/c5nr01744k

  2. Gold nanoparticles embedded in silica hollow nanospheres induced by compressed CO2 as an efficient catalyst for selective oxidation.

    PubMed

    Guo, Li; Zhang, Ran; Chen, Chen; Chen, Jizhong; Zhao, Xiuge; Chen, Angjun; Liu, Xuerui; Xiu, Yuhe; Hou, Zhenshan

    2015-03-01

    Metal nanoparticles embedded in hollow materials are important due to their wide applications in catalysis. In this work, we disclosed a nontraditional synthetic pathway to prepare silica hollow nanospheres by hydrothermal treatment in the presence of compressed CO2. Especially, the silica hollow nanospheres with an outer diameter of about 16 nm and an inner pore size of 7 nm were obtained using 1.0 MPa CO2. The formation mechanism of silica hollow nanospheres induced by CO2 was investigated by high-pressured UV/Vis spectroscopy. Moreover, gold nanoparticles (2.5 nm) embedded in the silica hollow nanospheres were prepared by a one-pot synthesis using HAuCl4 as a precursor. The current synthetic route of nano-catalysts was simple and facile, in which no etching agent was needed in the process of the hollow material preparation. Besides, this nano-catalyst showed an excellent catalytic performance in epoxidation of styrene with high conversion (82.2%) and selectivity (90.2%) toward styrene oxide, as well as in the selective oxidation of ethylbenzene with good conversion (26.6%) and selectivity (87.8%) toward acetophenone. Moreover, the Au nanoparticles (AuNPs) embedded in silica hollow nanospheres exhibited an excellent recyclability in both the oxidation reactions.

  3. Template-Assisting Preparation of Luminescent YAG:Nd³⁺ Nanoparticles and Hollow Nano-Beads.

    PubMed

    Hu, Zhongliang; Ma, Zhijun; Pan, Xuanzhao; Qiu, Jianrong

    2016-01-01

    Nanostructured YAG:Nd³⁺ is an interesting material with a wide range of applications. In this paper, we report the fabrication of luminescent YAG:Nd³⁺ nanoparticles via a simple template-assisting nano-casting technique. By optimizing the synthetic parameters, bead-like hollow YAG:Nd³⁺ nanoparticles with nano-porous walls were successfully prepared. Their porous and hollow structures, and strong photoluminescence in the "Human Optical Window" make the YAG:Nd³⁺ nanoparticles promising candidates for in-vivo applications.

  4. Fabrication of porous hollow silica nanoparticles and their applications in drug release control.

    PubMed

    Li, Zhu-Zhu; Wen, Li-Xiong; Shao, Lei; Chen, Jian-Feng

    2004-08-11

    Preparation and characterization of porous hollow silica nanoparticles (PHSN) for controlled release applications were investigated. Through orthogonally designed experiments, the optimal synthesis conditions for the preparation of PHSN were obtained and the produced PHSN were characterized by BET, SEM, TEM and IR. Scanning and transmission electron microscopy images revealed their hollow shell-core structure and also demonstrated that the size and shape of PHSN are determined by the templating CaCO3 nanoparticles. The produced PHSN were applied as a carrier to study the controlled release behaviors of Brilliant Blue F (BB), which was used as a model drug. Being loaded into the inner core and on the surfaces of the nanoparticles, BB was released slowly into a bulk solution for about 1140 min as compared to only 10 min for the normal SiO2 nanoparticles, thus exhibited a typical sustained release pattern without any burst effect. In addition, higher BET of the carriers, lower pH value and lower temperature prolonged BB release from PHSN, while stirring speed showed little influence on the release behavior. It showed that PHSN have a promising future in controlled drug delivery applications.

  5. Redox-Triggered Gatekeeper-Enveloped Starlike Hollow Silica Nanoparticles for Intelligent Delivery Systems.

    PubMed

    Zhao, Nana; Lin, Xinyi; Zhang, Qing; Ji, Zhaoxia; Xu, Fu-Jian

    2015-12-22

    The design and development of multifunctional carriers for drug delivery based on hollow nanoparticles (HNPs) have attracted intense interests. Ordinary spherical HNPs are demonstrated to be promising candidates. However, the application of HNPs with special morphologies has rarely been reported. HNPs with sharp horns are expected to own higher endocytosis efficiencies than spherical counterparts. In this work, novel starlike hollow silica nanoparticles (SHNPs) with different sizes are proposed as platforms for the fabrication of redox-triggered multifunctional systems for synergy of gene therapy and chemotherapy. The CD-PGEA gene vectors (consisting of β-CD cores and ethanolamine-functionalized poly(glycidyl methacrylate) (denoted BUCT-PGEA) arms) are introduced ingeniously onto the surfaces of SHNPs with plentiful disulfide bond-linked adamantine guests. The resulting supramolecular assemblies (SHNP-PGEAs) possess redox-responsive gatekeepers for loaded drugs in the cavities of SHNPs. Meanwhile, they also demonstrate excellent performances to deliver genes. The gene transfection efficiencies, controlled drug release behaviors, and synergistic antitumor effect of hollow silica-based carriers with different morphologies are investigated in detail. Compared with ordinary spherical HNP-based counterparts, SHNP-PGEA carriers with six sharp horns are proven to be superior gene vectors and possess better efficacy for cellular uptake and antitumor effects. The present multifunctional carriers based on SHNPs will have promising applications in drug/gene codelivery and cancer treatment.

  6. Smart hollow microspheres of chondroitin sulfate conjugates and magnetite nanoparticles for magnetic vector.

    PubMed

    Guilherme, Marcos R; Reis, Adriano V; Alves, Bruno R V; Kunita, Marcos H; Rubira, Adley F; Tambourgi, Elias B

    2010-12-01

    Smart hollow microspheres composed of vinyled-chondroitin sulfate conjugates (CSπ) and magnetite nanoparticles were obtained by the intermediate of a multiple emulsion in absence of a surfactant, attributable to stabilizing properties of the CS. It was formed an oil-water multiple emulsion in which the CS played a role as an anionic stabilizer for magnetite nanoparticles via complexation. Iron oxides were bonded to the microspheres by the formation of a complex of Fe(3+) ions on the crystalline phase with oxygen atoms at the carboxyl groups without their magnetic properties being affected. The average crystal size of embedded magnetite nanoparticles was approximately 16.5nm, indicative of a good dispersion in microspheres. Furthermore, the introduction of iron oxides resulted in microspheres with a higher diameter and a narrower particle size distribution.

  7. Smart hollow microspheres of chondroitin sulfate conjugates and magnetite nanoparticles for magnetic vector.

    PubMed

    Guilherme, Marcos R; Reis, Adriano V; Alves, Bruno R V; Kunita, Marcos H; Rubira, Adley F; Tambourgi, Elias B

    2010-12-01

    Smart hollow microspheres composed of vinyled-chondroitin sulfate conjugates (CSπ) and magnetite nanoparticles were obtained by the intermediate of a multiple emulsion in absence of a surfactant, attributable to stabilizing properties of the CS. It was formed an oil-water multiple emulsion in which the CS played a role as an anionic stabilizer for magnetite nanoparticles via complexation. Iron oxides were bonded to the microspheres by the formation of a complex of Fe(3+) ions on the crystalline phase with oxygen atoms at the carboxyl groups without their magnetic properties being affected. The average crystal size of embedded magnetite nanoparticles was approximately 16.5nm, indicative of a good dispersion in microspheres. Furthermore, the introduction of iron oxides resulted in microspheres with a higher diameter and a narrower particle size distribution. PMID:20832809

  8. Formation of nanotubes and hollow nanoparticles based on Kirkendall and diffusion processes: a review.

    PubMed

    Fan, Hong Jin; Gösele, Ulrich; Zacharias, Margit

    2007-10-01

    The Kirkendall effect is a consequence of the different diffusivities of atoms in a diffusion couple causing a supersaturation of lattice vacancies. This supersaturation may lead to a condensation of extra vacancies in the form of so-called "Kirkendall voids" close to the interface. On the macroscopic and micrometer scale these Kirkendall voids are generally considered as a nuisance because they deteriorate the properties of the interface. In contrast, in the nanoworld the Kirkendall effect has been positively used as a new fabrication route to designed hollow nano-objects. In this Review we summarize and discuss the demonstrated examples of hollow nanoparticles and nanotubes induced by the Kirkendall effect. Merits of this route are compared with other general methods for nanotube fabrication. Theories of the kinetics and thermodynamics are also reviewed and evaluated in terms of their relevance to experiments. Moreover, nanotube fabrication by solid-state reactions and non-Kirkendall type diffusion processes are covered.

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

  10. Controlled delivery of hollow corn protein nanoparticles via non-toxic crosslinking: in vivo and drug loading study.

    PubMed

    Xu, Helan; Shen, Li; Xu, Lan; Yang, Yiqi

    2015-02-01

    In this research, controlled delivery of hollow nanoparticles from zein, the corn storage protein, to different organs of mice was achieved via crosslinking using citric acid, a non-toxic polycarboxylic acid derived from starch. Besides, crosslinking significantly enhanced water stability of nanoparticles while preserving their drug loading efficiency. Protein nanoparticles have been widely investigated as vehicles for delivery of therapeutics. However, protein nanoparticles were not stable in physiological conditions, easily cleared by mononuclear phagocyte system (MPS), and thus mainly accumulated and degraded in spleen and liver, the major MPS organs. Effective delivery to major non-MPS organs, such as kidney, was usually difficult to achieve, as well as long resident time of nanoparticles. In this research, hollow zein nanoparticles were chemically crosslinked with citric acid. Controlled delivery and prolonged accumulation of the nanoparticles in kidney, one major non-MPS organ, were achieved. The nanoparticles showed improved stability in aqueous environment at pH 7.4 without affecting the adsorption of 5-FU, a common anticancer drug. In summary, citric acid crosslinked hollow zein nanoparticles could be potential vehicles for controllable delivery of anticancer therapeutics.

  11. Solution-based carbohydrate synthesis of individual solid, hollow, and porous carbon nanospheres using spray pyrolysis.

    PubMed

    Wang, Chengwei; Wang, Yuan; Graser, Jake; Zhao, Ran; Gao, Fei; O'Connell, Michael J

    2013-12-23

    A facile and scalable solution-based, spray pyrolysis synthesis technique was used to synthesize individual carbon nanospheres with specific surface area (SSA) up to 1106 m(2)/g using a novel metal-salt catalyzed reaction. The carbon nanosphere diameters were tunable from 10 nm to several micrometers by varying the precursor concentrations. Solid, hollow, and porous carbon nanospheres were achieved by simply varying the ratio of catalyst and carbon source without using any templates. These hollow carbon nanospheres showed adsorption of to 300 mg of dye per gram of carbon, which is more than 15 times higher than that observed for conventional carbon black particles. When evaluated as supercapacitor electrode materials, specific capacitances of up to 112 F/g at a current density of 0.1 A/g were observed, with no capacitance loss after 20,000 cycles.

  12. Hyaluronic Acid Modified Hollow Prussian Blue Nanoparticles Loading 10-hydroxycamptothecin for Targeting Thermochemotherapy of Cancer.

    PubMed

    Jing, Lijia; Shao, Shangmin; Wang, Yang; Yang, Yongbo; Yue, Xiuli; Dai, Zhifei

    2016-01-01

    This paper reported the fabrication of a multifunctional nanoplatform by modifying hollow Prussian blue nanoparticles with hyaluronic acid grafting polyethylene glycol, followed by loading 10-hydroxycamptothecin for tumor-targeted thermochemotherapy. It was found that the surface modification of hollow Prussian blue nanoparticles with hyaluronic acid grafting polyethylene endowed a great colloidal stability, long blood circulation time and the capability for targeting Hela cells over-expressing the CD44 receptor. The obtained nanoagent exhibited efficient photothermal effect and a light triggered and stepwise release behavior of 10-hydroxycamptothecin due to the strong optical absorption in the near-infrared region. The investigations on the body weight change, histological injury and blood biochemical indexes showed that such nanoagent had excellent biocompatibility for medical application. Both in vitro and in vivo experiments proved that the combination of chemotherapy and photothermal therapy through the agent of hyaluronic acid modified Prussian blue nanoparticles loading 10-hydroxycamptothecin could significantly improve the therapeutic efficacy compared with either therapy alone because of a good synergetic effect.

  13. Hyaluronic Acid Modified Hollow Prussian Blue Nanoparticles Loading 10-hydroxycamptothecin for Targeting Thermochemotherapy of Cancer

    PubMed Central

    Jing, Lijia; shao, shangmin; Wang, Yang; Yang, Yongbo; Yue, Xiuli; Dai, Zhifei

    2016-01-01

    This paper reported the fabrication of a multifunctional nanoplatform by modifying hollow Prussian blue nanoparticles with hyaluronic acid grafting polyethylene glycol, followed by loading 10-hydroxycamptothecin for tumor-targeted thermochemotherapy. It was found that the surface modification of hollow Prussian blue nanoparticles with hyaluronic acid grafting polyethylene endowed a great colloidal stability, long blood circulation time and the capability for targeting Hela cells over-expressing the CD44 receptor. The obtained nanoagent exhibited efficient photothermal effect and a light triggered and stepwise release behavior of 10-hydroxycamptothecin due to the strong optical absorption in the near-infrared region. The investigations on the body weight change, histological injury and blood biochemical indexes showed that such nanoagent had excellent biocompatibility for medical application. Both in vitro and in vivo experiments proved that the combination of chemotherapy and photothermal therapy through the agent of hyaluronic acid modified Prussian blue nanoparticles loading 10-hydroxycamptothecin could significantly improve the therapeutic efficacy compared with either therapy alone because of a good synergetic effect. PMID:26722372

  14. Inorganic hollow nanoparticles and nanotubes in nanomedicine Part 2: Imaging, diagnostic, and therapeutic applications.

    PubMed

    Son, Sang Jun; Bai, Xia; Lee, Sang Bok

    2007-08-01

    Inorganic nanoparticles, such as carbon nanotubes, quantum dots and gold nanoshells, have been adopted for biomedical use, due to their unique optical and physical properties. Compared to conventional materials, inorganic nanomaterials have several advantages such as simple preparative processes and precise control over their shape, composition and size. In addition, inorganic porous nanomaterials are fundamentally advantageous for developing multifunctional nanomaterials, due to their distinctive inner and outer surfaces. In this review, we describe recent developments of hollow and porous inorganic nanomaterials in nanomedicine, especially for imaging/diagnosis and photothermal therapy. PMID:17706548

  15. Hollow Fibers Networked with Perovskite Nanoparticles for H2 Production from Heavy Oil

    PubMed Central

    Jeon, Yukwon; Park, Dae-Hwan; Park, Joo-Il; Yoon, Seong-Ho; Mochida, Isao; Choy, Jin-Ho; Shul, Yong-Gun

    2013-01-01

    Design of catalytic materials has been highlighted to build ultraclean use of heavy oil including liquid-to-gas technology to directly convert heavy hydrocarbons into H2–rich gas fuels. If the H2 is produced from such heavy oil through high-active and durable catalysts in reforming process that is being constructed in hydrogen infrastructure, it will be addressed into renewable energy systems. Herein, the three different hollow fiber catalysts networked with perovskite nanoparticles, LaCr0.8Ru0.2O3, LaCr0.8Ru0.1Ni0.1O3, and LaCr0.8Ni0.2O3 were prepared by using activated carbon fiber as a sacrificial template for H2 production from heavy gas oil reforming. The most important findings were arrived at: (i) catalysts had hollow fibrous architectures with well-crystallized structures, (ii) hollow fibers had a high specific surface area with a particle size of ≈50 nm, and (iii) the Ru substituted ones showed high efficiency for H2 production with substantial durability under high concentrations of S, N, and aromatic compounds. PMID:24104596

  16. Optical trapping and control of nanoparticles inside evacuated hollow core photonic crystal fibers

    NASA Astrophysics Data System (ADS)

    Grass, David; Fesel, Julian; Hofer, Sebastian G.; Kiesel, Nikolai; Aspelmeyer, Markus

    2016-05-01

    We demonstrate an optical conveyor belt for levitated nanoparticles over several centimeters inside both air-filled and evacuated hollow-core photonic crystal fibers (HCPCF). Detection of the transmitted light field allows three-dimensional read-out of the particle center-of-mass motion. An additional laser enables axial radiation pressure based feedback cooling over the full fiber length. We show that the particle dynamics is a sensitive local probe for characterizing the optical intensity profile inside the fiber as well as the pressure distribution along the fiber axis. In contrast to some theoretical predictions, we find a linear pressure dependence inside the HCPCF, extending over three orders of magnitude from 0.2 mbar to 100 mbar. A targeted application is the controlled delivery of nanoparticles from ambient pressure into medium vacuum.

  17. Heterogeneous nanocomposites of silver selenide and hollow platinum nanoparticles toward methanol oxidation reaction

    NASA Astrophysics Data System (ADS)

    Cui, Penglei; He, Hongyan; Liu, Hui; Zhang, Suojiang; Yang, Jun

    2016-09-01

    Making use of the electronic coupling between different domains in composite nanomaterials is an effective way to enhance the activity of electrocatalysts. Herein, we demonstrate the preparation of nanocomposites consisting of silver selenide (Ag2Se) and platinum (Pt) nanoparticles with a hollow interior by combining the inside-out diffusion of Ag in core-shell Ag-Pt nanoparticles with the synthesis of highly active hydrophobic Se species. In specific, the Ag2Se-hPt nanocomposites are found to have superior activity and stability for methanol oxidation reaction in an acidic condition due to the strong electronic coupling effect between semiconductor and metal domains. This strategy may provide a greener and less expensive way to the large-scale synthesis of Pt-based nanocomposites, and might be used to generate other heterogeneous nanomaterials with technological importance.

  18. From core/shell to hollow Fe/γ-Fe₂O₃ nanoparticles: evolution of the magnetic behavior.

    PubMed

    Nemati, Z; Khurshid, H; Alonso, J; Phan, M H; Mukherjee, P; Srikanth, H

    2015-10-01

    High quality Fe/γ-Fe2O3 core/shell, core/void/shell, and hollow nanoparticles with two different sizes of 8 and 12 nm were synthesized, and the effect of morphology, surface and finite-size effects on their magnetic properties including the exchange bias (EB) effect were systematically investigated. We find a general trend for both systems that as the morphology changes from core/shell to core/void/shell, the magnetization of the system decays and inter-particle interactions become weaker, while the effective anisotropy and the EB effect increase. The changes are more drastic when the nanoparticles become completely hollow. Noticeably, the morphological change from core/shell to hollow increases the mean blocking temperature for the 12 nm particles but decreases for the 8 nm particles. The low-temperature magnetic behavior of the 12 nm particles changes from a collective super-spin-glass system mediated by dipolar interactions for the core/shell nanoparticles to a frustrated cluster glass-like state for the shell nanograins in the hollow morphology. On the other hand for the 8 nm nanoparticles core/shell and hollow particles the magnetic behavior is more similar, and a conventional spin glass-like transition is obtained at low temperatures. In the case of the hollow nanoparticles, the coupling between the inner and outer spin layers in the shell gives rise to an enhanced EB effect, which increases with increasing shell thickness. This indicates that the morphology of the shell plays a crucial role in this kind of exchange-biased systems.

  19. From core/shell to hollow Fe/γ-Fe2O3 nanoparticles: evolution of the magnetic behavior

    NASA Astrophysics Data System (ADS)

    Nemati, Z.; Khurshid, H.; Alonso, J.; Phan, M. H.; Mukherjee, P.; Srikanth, H.

    2015-10-01

    High quality Fe/γ-Fe2O3 core/shell, core/void/shell, and hollow nanoparticles with two different sizes of 8 and 12 nm were synthesized, and the effect of morphology, surface and finite-size effects on their magnetic properties including the exchange bias (EB) effect were systematically investigated. We find a general trend for both systems that as the morphology changes from core/shell to core/void/shell, the magnetization of the system decays and inter-particle interactions become weaker, while the effective anisotropy and the EB effect increase. The changes are more drastic when the nanoparticles become completely hollow. Noticeably, the morphological change from core/shell to hollow increases the mean blocking temperature for the 12 nm particles but decreases for the 8 nm particles. The low-temperature magnetic behavior of the 12 nm particles changes from a collective super-spin-glass system mediated by dipolar interactions for the core/shell nanoparticles to a frustrated cluster glass-like state for the shell nanograins in the hollow morphology. On the other hand for the 8 nm nanoparticles core/shell and hollow particles the magnetic behavior is more similar, and a conventional spin glass-like transition is obtained at low temperatures. In the case of the hollow nanoparticles, the coupling between the inner and outer spin layers in the shell gives rise to an enhanced EB effect, which increases with increasing shell thickness. This indicates that the morphology of the shell plays a crucial role in this kind of exchange-biased systems.

  20. Surface-enhanced Raman spectroscopy of double-shell hollow nanoparticles: electromagnetic and chemical enhancements.

    PubMed

    Mahmoud, Mahmoud A

    2013-05-28

    Enhancements of the Raman signal by the newly prepared gold-palladium and gold-platinum double-shell hollow nanoparticles were examined and compared with those using gold nanocages (AuNCs). The surface-enhanced Raman spectra (SERS) of thiophenol adsorbed on the surface of AuNCs assembled into a Langmuir-Blodgett monolayer were 10-fold stronger than AuNCs with an inner Pt or Pd shell. The chemical and electromagnetic enhancement mechanisms for these hollow nanoparticles were further proved by comparing the Raman enhancement of nitrothiophenol and nitrotoulene. Nitrothiophenol binds to the surface of the nanoparticles by covalent interaction, and Raman enhancement by both the two mechanisms is possible, while nitrotoulene does not form any chemical bond with the surface of the nanoparticles and hence no chemical enhancement is expected. Based on discrete dipole approximation (DDA) calculations and the experimental SERS results, AuNCs introduced a high electromagnetic enhancement, while the nanocages with inner Pt or Pd shell have a strong chemical enhancement. The optical measurements of the localized surface plasmon resonance (LSPR) of the nanocages with an outer Au shell and an inner Pt or Pd shell were found, experimentally and theoretically, to be broad compared with AuNCs. The possible reason could be due to the decrease of the coherence time of Au oscillated free electrons and fast damping of the plasmon energy. This agreed well with the fact that a Pt or Pd inner nanoshell decreases the electromagnetic field of the outer Au nanoshell while increasing the SERS chemical enhancement.

  1. Enhancing the Electrocatalytic Property of Hollow Structured Platinum Nanoparticles for Methanol Oxidation Through A Hybrid Construction

    PubMed Central

    Feng, Yan; Liu, Hui; Wang, Pengfei; Ye, Feng; Tan, Qiangqiang; Yang, Jun

    2014-01-01

    The integration of different components into a hybrid nanosystem for the utilization of the synergistic effects is an effective way to design the electrocatalysts. Herein, we demonstrate a hybrid strategy to enhance the electrocatalytic property of hollow structured Pt nanoparticles for methanol oxidation reaction. This strategy begins with the preparation of bimetallic Ag-Pt nanoparticles with a core-shell construction. Element sulfur is then added to transform the core-shell Ag-Pt nanostructures into hybrid nanodimers consisting of Ag2S nanocrystals and remaining Pt domains with intact hollow interiors (Ag2S-hPt). Finally, Au is deposited at the surface of the Ag2S domain in each hetero-dimer, resulting in the formation of ternary Ag2S-Au-hPt nanocomposites with solid-state interfaces. The ternary nanocomposites exhibit enhanced electrocatalytic property toward methanol oxidation due to the strong electronic coupling between Pt and other domains in the hybrid particles. The concept might be used toward the design and synthesis of other hetero-nanostructures with technological importance. PMID:25160947

  2. Fabrication of high specificity hollow mesoporous silica nanoparticles assisted by Eudragit for targeted drug delivery.

    PubMed

    She, Xiaodong; Chen, Lijue; Velleman, Leonora; Li, Chengpeng; Zhu, Haijin; He, Canzhong; Wang, Tao; Shigdar, Sarah; Duan, Wei; Kong, Lingxue

    2015-05-01

    Hollow mesoporous silica nanoparticles (HMSNs) are one of the most promising carriers for effective drug delivery due to their large surface area, high volume for drug loading and excellent biocompatibility. However, the non-ionic surfactant templated HMSNs often have a broad size distribution and a defective mesoporous structure because of the difficulties involved in controlling the formation and organization of micelles for the growth of silica framework. In this paper, a novel "Eudragit assisted" strategy has been developed to fabricate HMSNs by utilising the Eudragit nanoparticles as cores and to assist in the self-assembly of micelle organisation. Highly dispersed mesoporous silica spheres with intact hollow interiors and through pores on the shell were fabricated. The HMSNs have a high surface area (670 m(2)/g), small diameter (120 nm) and uniform pore size (2.5 nm) that facilitated the effective encapsulation of 5-fluorouracil within HMSNs, achieving a high loading capacity of 194.5 mg(5-FU)/g(HMSNs). The HMSNs were non-cytotoxic to colorectal cancer cells SW480 and can be bioconjugated with Epidermal Growth Factor (EGF) for efficient and specific cell internalization. The high specificity and excellent targeting performance of EGF grafted HMSNs have demonstrated that they can become potential intracellular drug delivery vehicles for colorectal cancers via EGF-EGFR interaction. PMID:25617610

  3. Multifunctional hollow gold nanoparticles designed for triple combination therapy and CT imaging.

    PubMed

    Park, Jaesook; Park, Jin; Ju, Eun Jin; Park, Seok Soon; Choi, Jinhyang; Lee, Jae Hee; Lee, Kyoung Jin; Shin, Seol Hwa; Ko, Eun Jung; Park, Intae; Kim, Chulhee; Hwang, Jung Jin; Lee, Jung Shin; Song, Si Yeol; Jeong, Seong-Yun; Choi, Eun Kyung

    2015-06-10

    Hollow gold nanoparticles (HGNP) are a novel class of hybrid metal nanoparticles whose unique optical and morphological properties have spawned new applications including more effective cancer therapy. The shell thickness of HGNPs can tune the surface plasmon resonance to the near infrared light, resulting in photothermal ablation of tumors with optimal light penetration in tissue. The hollow cavity within a HGNP is able to accommodate a high payload of chemotherapeutic agents. They have also been used for enhancing radiosensitization in tumors during radiotherapy due to the high X-ray absorption capability of gold particles. However, no report has yet been published that utilize HGNPs for the triple combination therapy and CT imaging. In this study, we synthesized HGNPs which exhibit better response to radiation for therapy and imaging and demonstrated the effects of combined chemotherapy, thermal and radiotherapy. This combination strategy presented delayed tumor growth by 4.3-fold and reduced tumor's weight by 6.8-fold compared to control tumors. In addition, we demonstrated the feasibility of HGNP as a CT imaging agent. It is expected that translating these capabilities to human cancer patients could dramatically increase the antitumor effect and potentially overcome resistance to chemotherapeutic agents and radiation. PMID:25863273

  4. Tuning the synthesis of platinum-copper nanoparticles with a hollow core and porous shell for the selective hydrogenation of furfural to furfuryl alcohol

    NASA Astrophysics Data System (ADS)

    Huang, Shuangshuang; Yang, Nating; Wang, Shibin; Sun, Yuhan; Zhu, Yan

    2016-07-01

    Pt-Cu nanoparticles constructed with a hollow core and porous shell have been synthesized in which Pt-Cu cages with multiporous outermost shells are formed at the initial stage and then the Pt and Cu atoms in solution continuously fed these hollow-core of cages by passing through the porous tunnels of the outermost shells, finally leading to the formation of hollow structures with different sizes. Furthermore, these hollow-core Pt-Cu nanoparticles are more effective than the solid-core Pt-Cu nanoparticles for the catalytic hydrogenation of furfural toward furfuryl alcohol. The former can achieve almost 100% conversion of furfural with 100% selectivity toward the alcohol.Pt-Cu nanoparticles constructed with a hollow core and porous shell have been synthesized in which Pt-Cu cages with multiporous outermost shells are formed at the initial stage and then the Pt and Cu atoms in solution continuously fed these hollow-core of cages by passing through the porous tunnels of the outermost shells, finally leading to the formation of hollow structures with different sizes. Furthermore, these hollow-core Pt-Cu nanoparticles are more effective than the solid-core Pt-Cu nanoparticles for the catalytic hydrogenation of furfural toward furfuryl alcohol. The former can achieve almost 100% conversion of furfural with 100% selectivity toward the alcohol. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr03894h

  5. Improved luminescence in water-soluble hollow LaF3:Eu3+ nanoparticles by introducing Li+ ions

    NASA Astrophysics Data System (ADS)

    Fan, Ting; Lü, Jiantao; Lin, Futian; Zhou, Zifan

    2016-04-01

    Improved red emission in polyvinylpyrrolidone (PVP)-coated hollow LaF3:Eu3+ nanoparticles by introducing Li+ ions was found for the first time via a one-step template-free hydrothermal method. The hollow formation can be attributed to self-recrystallization and a local Ostwald ripening thermodynamic process. Pores were clearly seen and widely distributed in all LaF3 nanoparticles. The introduction of Li+ ions did not introduce new crystalline phases and resulted in little change in size and morphology of the LaF3 nanoparticles. The main diffraction peaks were found to shift slightly with the Li+ doping concentrations, which indicates that Li+ changes the crystal field environment of Eu3+. The excitation and red emission intensity both doubled when codoped with 7 mol% Li+ ions. The widely distributed pores and improved luminescence properties of our nanoparticles facilitated the construction of new nanocomposites for novel biological applications.

  6. Differences between individual ZSM-5 crystals in forming hollow single crystals and mesopores during base leaching.

    PubMed

    Fodor, Daniel; Krumeich, Frank; Hauert, Roland; van Bokhoven, Jeroen A

    2015-04-13

    After base treatment of ZSM-5 crystals below 100 nm in size, TEM shows hollow single crystals with a 10 nm shell. SEM images confirm that the shell is well- preserved even after prolonged treatment. Determination of the Si/Al ratios with AAS and XPS in combination with argon sputtering reveals aluminum zoning of the parent zeolite, and the total pore volume increases in the first two hours of base treatment. In corresponding TEM images, the amount of hollow crystals are observed to increase during the first two hours of base treatment, and intact crystals are visible even after 10 h of leaching; these observations indicate different dissolution rates between individual crystals. TEM of large, commercially available ZSM-5 crystals shows inhomogeneous distribution of mesopores among different crystals, which points to the existence of structural differences between individual crystals. Only tetrahedrally coordinated aluminum is detected with (27) Al MAS NMR after the base leaching of nano-sized ZSM-5.

  7. Synthesis of Hollow Gold-Silver Alloyed Nanoparticles: A "Galvanic Replacement" Experiment for Chemistry and Engineering Students

    ERIC Educational Resources Information Center

    Jenkins, Samir V.; Gohman, Taylor D.; Miller, Emily K.; Chen, Jingyi

    2015-01-01

    The rapid academic and industrial development of nanotechnology has led to its implementation in laboratory teaching for undergraduate-level chemistry and engineering students. This laboratory experiment introduces the galvanic replacement reaction for synthesis of hollow metal nanoparticles and investigates the optical properties of these…

  8. One-step synthesis of amine-functionalized hollow mesoporous silica nanoparticles as efficient antibacterial and anticancer materials

    PubMed Central

    Hao, Nanjing; Jayawardana, Kalana W.; Chen, Xuan; De Zoysa, Thareendra

    2015-01-01

    In this study, amine-functionalized hollow mesoporous silica nanoparticles with an average diameter of ~100 nm and shell thickness of ~20 nm were prepared by an one-step process. This new nanoparticulate system exhibited excellent killing efficiency against mycobacterial (M. smegmatis strain mc2 651) and cancer cells (A549). PMID:25562524

  9. Hollow structured carbon-supported nickel cobaltite nanoparticles as an efficient bifunctional electrocatalyst for the oxygen reduction and evolution reaction

    DOE PAGESBeta

    Wang, Jie; Han, Lili; Lin, Ruoqian; Xin, Huolin L.; Wang, Deli; Wu, Zexing

    2016-01-05

    Here, the exploration of efficient electrocatalysts for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is essential for fuel cells and metal-air batteries. In this study, we developed 3D hollow-structured NiCo2O4/C nanoparticles with interconnected pores as bifunctional electrocatalysts, which are transformed from solid NiCo2 alloy nanoparticles through the Kirkendall effect. The unique hollow structure of NiCo2O4 nanoparticles increases the number of active sites and improves contact with the electrolyte to result in excellent ORR and OER performances. In addition, the hollow-structured NiCo2O4/C nanoparticles exhibit superior long-term stability for both the ORR and OER compared to commercial Pt/C.more » The template- and surfactant-free synthetic strategy could be used for the low-cost and large-scale synthesis of hollow-structured materials, which would facilitate the screening of high-efficiency catalysts for energy conversion.« less

  10. Iron oxide nanoparticle layer templated by polydopamine spheres: a novel scaffold toward hollow-mesoporous magnetic nanoreactors.

    PubMed

    Huang, Liang; Ao, Lijiao; Xie, Xiaobin; Gao, Guanhui; Foda, Mohamed F; Su, Wu

    2015-01-14

    Superparamagnetic iron oxide nanoparticle layers with high packing density and controlled thickness were in situ deposited on metal-affinity organic templates (polydopamine spheres), via one-pot thermal decomposition. The as synthesized hybrid structure served as a facile nano-scaffold toward hollow-mesoporous magnetic carriers, through surfactant-assisted silica encapsulation and its subsequent calcination. Confined but accessible gold nanoparticles were successfully incorporated into these carriers to form a recyclable catalyst, showing quick magnetic response and a large surface area (642.5 m(2) g(-1)). Current nano-reactors exhibit excellent catalytic performance and high stability in reduction of 4-nitrophenol, together with convenient magnetic separability and good reusability. The integration of compact iron oxide nanoparticle layers with programmable polydopamine templates paves the way to fabricate magnetic-response hollow structures, with high permeability and multi-functionality.

  11. Synthesis of core–shell AlOOH hollow nanospheres by reacting Al nanoparticles with water

    NASA Astrophysics Data System (ADS)

    Lozhkomoev, A. S.; Glazkova, E. A.; Bakina, O. V.; Lerner, M. I.; Gotman, I.; Gutmanas, E. Y.; Kazantsev, S. O.; Psakhie, S. G.

    2016-05-01

    A novel route for the synthesis of boehmite nanospheres with a hollow core and the shell composed of highly crumpled AlOOH nanosheets by oxidizing Al nanopowder in pure water under mild processing conditions is described. The stepwise events of Al transformation into boehmite are followed by monitoring the pH in the reaction medium. A mechanism of formation of hollow AlOOH nanospheres with a well-defined shape and crystallinity is proposed which includes the hydration of the Al oxide passivation layer, local corrosion of metallic Al accompanied by hydrogen evolution, the rupture of the protective layer, the dissolution of Al from the particle interior and the deposition of AlOOH nanosheets on the outer surface. In contrast to previously reported methods of boehmite nanoparticle synthesis, the proposed method is simple, and environmentally friendly and allows the generation of hydrogen gas as a by-product. Due to their high surface area and high, slit-shaped nanoporosity, the synthesized AlOOH nanostructures hold promise for the development of more effective catalysts, adsorbents, vaccines and drug carriers.

  12. Synthesis of core-shell AlOOH hollow nanospheres by reacting Al nanoparticles with water

    NASA Astrophysics Data System (ADS)

    Lozhkomoev, A. S.; Glazkova, E. A.; Bakina, O. V.; Lerner, M. I.; Gotman, I.; Gutmanas, E. Y.; Kazantsev, S. O.; Psakhie, S. G.

    2016-05-01

    A novel route for the synthesis of boehmite nanospheres with a hollow core and the shell composed of highly crumpled AlOOH nanosheets by oxidizing Al nanopowder in pure water under mild processing conditions is described. The stepwise events of Al transformation into boehmite are followed by monitoring the pH in the reaction medium. A mechanism of formation of hollow AlOOH nanospheres with a well-defined shape and crystallinity is proposed which includes the hydration of the Al oxide passivation layer, local corrosion of metallic Al accompanied by hydrogen evolution, the rupture of the protective layer, the dissolution of Al from the particle interior and the deposition of AlOOH nanosheets on the outer surface. In contrast to previously reported methods of boehmite nanoparticle synthesis, the proposed method is simple, and environmentally friendly and allows the generation of hydrogen gas as a by-product. Due to their high surface area and high, slit-shaped nanoporosity, the synthesized AlOOH nanostructures hold promise for the development of more effective catalysts, adsorbents, vaccines and drug carriers.

  13. Synthesis of core-shell AlOOH hollow nanospheres by reacting Al nanoparticles with water.

    PubMed

    Lozhkomoev, A S; Glazkova, E A; Bakina, O V; Lerner, M I; Gotman, I; Gutmanas, E Y; Kazantsev, S O; Psakhie, S G

    2016-05-20

    A novel route for the synthesis of boehmite nanospheres with a hollow core and the shell composed of highly crumpled AlOOH nanosheets by oxidizing Al nanopowder in pure water under mild processing conditions is described. The stepwise events of Al transformation into boehmite are followed by monitoring the pH in the reaction medium. A mechanism of formation of hollow AlOOH nanospheres with a well-defined shape and crystallinity is proposed which includes the hydration of the Al oxide passivation layer, local corrosion of metallic Al accompanied by hydrogen evolution, the rupture of the protective layer, the dissolution of Al from the particle interior and the deposition of AlOOH nanosheets on the outer surface. In contrast to previously reported methods of boehmite nanoparticle synthesis, the proposed method is simple, and environmentally friendly and allows the generation of hydrogen gas as a by-product. Due to their high surface area and high, slit-shaped nanoporosity, the synthesized AlOOH nanostructures hold promise for the development of more effective catalysts, adsorbents, vaccines and drug carriers. PMID:27053603

  14. Spin-glass-like freezing of inner and outer surface layers in hollow γ-Fe2O3 nanoparticles

    NASA Astrophysics Data System (ADS)

    Khurshid, Hafsa; Lampen-Kelley, Paula; Iglesias, Òscar; Alonso, Javier; Phan, Manh-Huong; Sun, Cheng-Jun; Saboungi, Marie-Louise; Srikanth, Hariharan

    2015-10-01

    Disorder among surface spins is a dominant factor in the magnetic response of magnetic nanoparticle systems. In this work, we examine time-dependent magnetization in high-quality, monodisperse hollow maghemite nanoparticles (NPs) with a 14.8 ± 0.5 nm outer diameter and enhanced surface-to-volume ratio. The nanoparticle ensemble exhibits spin-glass-like signatures in dc magnetic aging and memory protocols and ac magnetic susceptibility. The dynamics of the system slow near 50 K, and become frozen on experimental time scales below 20 K. Remanence curves indicate the development of magnetic irreversibility concurrent with the freezing of the spin dynamics. A strong exchange-bias effect and its training behavior point to highly frustrated surface spins that rearrange much more slowly than interior spins. Monte Carlo simulations of a hollow particle corroborate strongly disordered surface layers with complex energy landscapes that underlie both glass-like dynamics and magnetic irreversibility. Calculated hysteresis loops reveal that magnetic behavior is not identical at the inner and outer surfaces, with spins at the outer surface layer of the 15 nm hollow particles exhibiting a higher degree of frustration. Our combined experimental and simulated results shed light on the origin of spin-glass-like phenomena and the important role played by the surface spins in magnetic hollow nanostructures.

  15. Spin-glass-like freezing of inner and outer surface layers in hollow γ-Fe2O3 nanoparticles.

    PubMed

    Khurshid, Hafsa; Lampen-Kelley, Paula; Iglesias, Òscar; Alonso, Javier; Phan, Manh-Huong; Sun, Cheng-Jun; Saboungi, Marie-Louise; Srikanth, Hariharan

    2015-01-01

    Disorder among surface spins is a dominant factor in the magnetic response of magnetic nanoparticle systems. In this work, we examine time-dependent magnetization in high-quality, monodisperse hollow maghemite nanoparticles (NPs) with a 14.8 ± 0.5 nm outer diameter and enhanced surface-to-volume ratio. The nanoparticle ensemble exhibits spin-glass-like signatures in dc magnetic aging and memory protocols and ac magnetic susceptibility. The dynamics of the system slow near 50 K, and become frozen on experimental time scales below 20 K. Remanence curves indicate the development of magnetic irreversibility concurrent with the freezing of the spin dynamics. A strong exchange-bias effect and its training behavior point to highly frustrated surface spins that rearrange much more slowly than interior spins. Monte Carlo simulations of a hollow particle corroborate strongly disordered surface layers with complex energy landscapes that underlie both glass-like dynamics and magnetic irreversibility. Calculated hysteresis loops reveal that magnetic behavior is not identical at the inner and outer surfaces, with spins at the outer surface layer of the 15 nm hollow particles exhibiting a higher degree of frustration. Our combined experimental and simulated results shed light on the origin of spin-glass-like phenomena and the important role played by the surface spins in magnetic hollow nanostructures. PMID:26503506

  16. Spin-glass-like freezing of inner and outer surface layers in hollow γ-Fe2O3 nanoparticles

    PubMed Central

    Khurshid, Hafsa; Lampen-Kelley, Paula; Iglesias, Òscar; Alonso, Javier; Phan, Manh-Huong; Sun, Cheng-Jun; Saboungi, Marie-Louise; Srikanth, Hariharan

    2015-01-01

    Disorder among surface spins is a dominant factor in the magnetic response of magnetic nanoparticle systems. In this work, we examine time-dependent magnetization in high-quality, monodisperse hollow maghemite nanoparticles (NPs) with a 14.8 ± 0.5 nm outer diameter and enhanced surface-to-volume ratio. The nanoparticle ensemble exhibits spin-glass-like signatures in dc magnetic aging and memory protocols and ac magnetic susceptibility. The dynamics of the system slow near 50 K, and become frozen on experimental time scales below 20 K. Remanence curves indicate the development of magnetic irreversibility concurrent with the freezing of the spin dynamics. A strong exchange-bias effect and its training behavior point to highly frustrated surface spins that rearrange much more slowly than interior spins. Monte Carlo simulations of a hollow particle corroborate strongly disordered surface layers with complex energy landscapes that underlie both glass-like dynamics and magnetic irreversibility. Calculated hysteresis loops reveal that magnetic behavior is not identical at the inner and outer surfaces, with spins at the outer surface layer of the 15 nm hollow particles exhibiting a higher degree of frustration. Our combined experimental and simulated results shed light on the origin of spin-glass-like phenomena and the important role played by the surface spins in magnetic hollow nanostructures. PMID:26503506

  17. Iron oxide nanoparticle layer templated by polydopamine spheres: a novel scaffold toward hollow-mesoporous magnetic nanoreactors

    NASA Astrophysics Data System (ADS)

    Huang, Liang; Ao, Lijiao; Xie, Xiaobin; Gao, Guanhui; Foda, Mohamed F.; Su, Wu

    2014-12-01

    Superparamagnetic iron oxide nanoparticle layers with high packing density and controlled thickness were in situ deposited on metal-affinity organic templates (polydopamine spheres), via one-pot thermal decomposition. The as synthesized hybrid structure served as a facile nano-scaffold toward hollow-mesoporous magnetic carriers, through surfactant-assisted silica encapsulation and its subsequent calcination. Confined but accessible gold nanoparticles were successfully incorporated into these carriers to form a recyclable catalyst, showing quick magnetic response and a large surface area (642.5 m2 g-1). Current nano-reactors exhibit excellent catalytic performance and high stability in reduction of 4-nitrophenol, together with convenient magnetic separability and good reusability. The integration of compact iron oxide nanoparticle layers with programmable polydopamine templates paves the way to fabricate magnetic-response hollow structures, with high permeability and multi-functionality.Superparamagnetic iron oxide nanoparticle layers with high packing density and controlled thickness were in situ deposited on metal-affinity organic templates (polydopamine spheres), via one-pot thermal decomposition. The as synthesized hybrid structure served as a facile nano-scaffold toward hollow-mesoporous magnetic carriers, through surfactant-assisted silica encapsulation and its subsequent calcination. Confined but accessible gold nanoparticles were successfully incorporated into these carriers to form a recyclable catalyst, showing quick magnetic response and a large surface area (642.5 m2 g-1). Current nano-reactors exhibit excellent catalytic performance and high stability in reduction of 4-nitrophenol, together with convenient magnetic separability and good reusability. The integration of compact iron oxide nanoparticle layers with programmable polydopamine templates paves the way to fabricate magnetic-response hollow structures, with high permeability and multi

  18. Cobalt-Nanocrystal-Assembled Hollow Nanoparticles for Electrocatalytic Hydrogen Generation from Neutral-pH Water.

    PubMed

    Liu, Bingrui; Zhang, Lin; Xiong, Weilin; Ma, Mingming

    2016-06-01

    Highly active and stable electrocatalysts for hydrogen generation from neutral-pH water are highly desired, but very difficult to achieve. Herein we report a facile synthetic approach to cobalt nanocrystal assembled hollow nanoparticles (Co-HNP), which serve as an electrocatalyst for hydrogen generation from neutral-pH water. An electrode composed of Co-HNP on a carbon cloth (CC) produces cathodic current densities of 10 and 100 mA cm(-2) at overpotentials of -85 mV and -237 mV, respectively. The Co-HNP/CC electrode retains its high activity after 20 h hydrogen generation at a high current density of 150 mA cm(-2) , indicating the superior activity and stability of Co-HNP as electrocatalyst.

  19. Functionalized Hollow Mesoporous Silica Nanoparticles for Tumor Vasculature Targeting and PET Image-Guided Drug Delivery

    PubMed Central

    Chakravarty, Rubel; Goel, Shreya; Hong, Hao; Chen, Feng; Valdovinos, Hector F.; Hernandez, Reinier; Barnhart, Todd E.; Cai, Weibo

    2014-01-01

    Aim Development of multifunctional and well-dispersed hollow mesoporous silica nanoparticles (HMSNs) for tumor vasculature targeted drug delivery and positron emission tomography (PET) imaging. Materials and Methods Amine functionalized HMSNs (150–250 nm) were conjugated with a macrocyclic chelator, NOTA, PEGylated and loaded with anti-angiogenesis drug, Sunitinib. Cyclo(Arg-Gly-Asp-D-Tyr-Lys) (cRGDyK) peptide was attached to the nanoconjugate and radiolabeled with 64Cu for PET imaging. Results 64Cu-NOTA-HMSN-PEG-cRGDyK exhibited integrin specific uptake both in vitro and in vivo. PET results indicated ~ 8 %ID/g uptake of targeted nanoconjugates in U87MG tumors, which correlated well with ex vivo and histological analyses. Enhanced tumor targeted delivery of sunitinib was also observed. Conclusions We successfully developed tumor vasculature targeted HMSNs for PET imaging and image guided drug delivery. PMID:25955122

  20. Polyethersulfone hollow fiber modified with poly(styrenesulfonate) and Pd nanoparticles for catalytic reaction

    NASA Astrophysics Data System (ADS)

    Emin, C.; Gu, Y.; Remigy, J.-C.; Lahitte, J.-F.

    2015-07-01

    The aim of this work is the synthesis of polymer-stabilized Pd nanoparticles (PdNP) inside a functionalized polymeric porous membrane in order to develop hybrid catalytic membrane reactors and to test them in model metal-catalyzed organic reactions. For this goal, a polymeric membrane support (Polyethersulfone hollow fiber-shaped) was firstly functionalized with an ionogenic polymer (i.e. poly(styrenesulfonate) capable to retain PdNP precursors using an UV photo-grafting method. PdNP were then generated inside the polymeric matrix by chemical reduction of precursor salts (intermatrix synthesis). The catalytic performance of the PdNP catalytic membranes was evaluated using reduction of nitrophenol by sodium borohydride (NaBH4) in water.

  1. Simple and Rapid High-Yield Synthesis and Size Sorting of Multibranched Hollow Gold Nanoparticles with Highly Tunable NIR Plasmon Resonances.

    PubMed

    Blanch, Adam J; Döblinger, Markus; Rodríguez-Fernández, Jessica

    2015-09-16

    Branched gold nanoparticles with sharp tips are considered excellent candidates for sensing and field enhancement applications. Here, a rapid and simple synthesis strategy is presented that generates highly branched gold nanoparticles with hollow cores and a ca.100% yield through a simple one-pot seedless reaction at room temperature in the presence of Triton X-100. It is shown that multibranched hollow gold nanoparticles of tunable dimensions, branch density and branch length can be obtained by adjusting the concentrations of the reactants. Insights into the formation mechanism point toward an aggregative type of growth involving hollow core formation first, and branching thereafter. The pronounced near-infrared (NIR) plasmon band of the nanoparticles is due to the combined contribution from hollowness and branching, and can be tuned over a wide range (≈700-2000 nm). It is also demonstrated that the high environmental sensitivity of colloidal dispersions based on multibranched hollow gold nanoparticles can be boosted even further by separating the nanoparticles into fractions of given sizes and improved monodispersity by means of a glycerol density gradient. The possibility to obtain highly monodisperse multibranched hollow gold nanoparticles with predictable dimensions (50-300 nm) and branching and, therefore, tailored NIR plasmonic properties, highlights their potential for theranostic applications.

  2. Hollow ruthenium nanoparticles with small dimensions derived from Ni@Ru core@shell structure: synthesis and enhanced catalytic dehydrogenation of ammonia borane.

    PubMed

    Chen, Guozhu; Desinan, Stefano; Rosei, Renzo; Rosei, Federico; Ma, Dongling

    2012-08-18

    Hollow Ru nanoparticles with ~14 nm diameter and ~2 nm shell thickness are reported for the first time, by removal of Ni from the delicately designed Ni@Ru core@shell NPs. Such hollow Ru NPs exhibit enhanced catalytic activity in the dehydrogenation of ammonia borane with respect to solid ones. PMID:22773309

  3. In situ assembly of well-dispersed gold nanoparticles on hierarchical double-walled nickel silicate hollow nanofibers as an efficient and reusable hydrogenation catalyst.

    PubMed

    Jin, Renxi; Yang, Yang; Li, Yunfeng; Fang, Lin; Xing, Yan; Song, Shuyan

    2014-05-28

    Highly dispersive and ultrafine Au nanoparticles were effectively immobilized on the surface of hierarchical double-walled nickel silicate hollow nanofibers assembled by ultrathin nanosheets, which showed remarkable catalytic performances as an efficient and reusable hydrogenation catalyst.

  4. In vivo delivery of bovine viral diahorrea virus, E2 protein using hollow mesoporous silica nanoparticles.

    PubMed

    Mahony, D; Cavallaro, A S; Mody, K T; Xiong, L; Mahony, T J; Qiao, S Z; Mitter, N

    2014-06-21

    Our work focuses on the application of mesoporous silica nanoparticles as a combined delivery vehicle and adjuvant for vaccine applications. Here we present results using the viral protein, E2, from bovine viral diarrhoea virus (BVDV). BVDV infection occurs in the target species of cattle and sheep herds worldwide and is therefore of economic importance. E2 is a major immunogenic determinant of BVDV and is an ideal candidate for the development of a subunit based nanovaccine using mesoporous silica nanoparticles. Hollow type mesoporous silica nanoparticles with surface amino functionalisation (termed HMSA) were characterised and assessed for adsorption and desorption of E2. A codon-optimised version of the E2 protein (termed Opti-E2) was produced in Escherichia coli. HMSA (120 nm) had an adsorption capacity of 80 μg Opti-E2 per mg HMSA and once bound E2 did not dissociate from the HMSA. Immunisation studies in mice with a 20 μg dose of E2 adsorbed to 250 μg HMSA was compared to immunisation with Opti-E2 (50 μg) together with the traditional adjuvant Quillaja saponaria Molina tree saponins (QuilA, 10 μg). The humoral responses with the Opti-E2/HMSA nanovaccine although slightly lower than those obtained for the Opti-E2 + QuilA group demonstrated that HMSA particles are an effective adjuvant that stimulated E2-specific antibody responses. Importantly the cell-mediated immune responses were consistently high in all mice immunised with Opti-E2/HMSA nanovaccine formulation. Therefore we have shown the Opti-E2/HMSA nanoformulation acts as an excellent adjuvant that gives both T-helper 1 and T-helper 2 mediated responses in a small animal model. This study has provided proof-of-concept towards the development of an E2 subunit nanoparticle based vaccine. PMID:24811899

  5. Assembling metal oxide nanocrystals into dense, hollow, porous nanoparticles for lithium-ion and lithium-oxygen battery application.

    PubMed

    Ming, Jun; Wu, Yingqiang; Park, Jin-Bum; Lee, Joong Kee; Zhao, Fengyu; Sun, Yang-Kook

    2013-11-01

    New dense hollow porous (DHP) metal oxide nanoparticles that are smaller than 100 nm and composed of Co3O4, FeOx, NiO and MnOx were prepared by densely assembling metal oxide nanocrystals based on the hard-template method using a carbon colloid as a sacrificial core. These nanoparticles are quite different from the traditional particles as their hollow interior originates from the stacking of nanocrystals rather than a spherical shell. The DHP nanoparticles preserve the intriguing properties of nanocrystals and possess desirable surface area and pore volume that enhance the active surface, which ultimately benefits applications such as lithium-ion batteries. The DHP Co3O4 nanoparticles demonstrated an enhanced capacity of 1168 mA h g(-1) at 100 mA g(-1)vs. 590 mA h g(-1) of powders and stable cycling performance greater than 250 cycles when used as an anode material. Most importantly, the electrochemical performance of DHP Co3O4 nanoparticles in a lithium-O2 battery was also investigated for the first time. A low charge potential of ∼4.0 V, a high discharge voltage near 2.74 V and a long cycle ability greater than 100 cycles at a delivered capacity of 2000 mA h g(-1) (current density, 200 mA g(-1)) were observed. The performances were considerably improved compared to recent results of mesoporous Co3O4, Co3O4 nanoparticles and a composite of Co3O4/RGO and Co3O4/Pd. Therefore, it would be promising to investigate such properties of DHP nanoparticles or other hollow metal (oxide) particles for the popular lithium-air battery.

  6. Spin-glass-like freezing of inner and outer surface layers in hollow γ-Fe2O3 nanoparticles

    DOE PAGESBeta

    Khurshid, Hafsa; Lampen-Kelley, Paula; Iglesias, Òscar; Alonso, Javier; Phan, Manh-Huong; Sun, Cheng-Jun; Saboungi, Marie-Louise; Srikanth, Hariharan

    2015-10-27

    Disorder among surface spins largely dominates the magnetic response of ultrafine magnetic particle systems. In this work, we examine time-dependent magnetization in high-quality, monodisperse hollow maghemite nanoparticles (NPs) with a 14.8±0.5 nm outer diameter and enhanced surface-to-volume ratio. The nanoparticle ensemble exhibits spin-glass-like signatures in dc magnetic aging and memory protocols and ac magnetic susceptibility. The dynamics of the system slow near 50 K, and becomes frozen on experimental time scales below 20 K. Remanence curves indicate the development of magnetic irreversibility concurrent with the freezing of the spin dynamics. A strong exchange-bias effect and its training behavior point tomore » highly frustrated surface spins that rearrange much more slowly than interior spins with bulk coordination. Monte Carlo simulations of a hollow particle reproducing the experimental morphology corroborate strongly disordered surface layers with complex energy landscapes that underlie both glass-like dynamics and magnetic irreversibility. Calculated hysteresis loops reveal that magnetic behavior is not identical at the inner and outer surfaces, with spins at the outer surface layer of the 15 nm hollow particles exhibiting a higher degree of frustration. Lastly, our combined experimental and simulated results shed light on the origin of spin-glass-like phenomena and the important role played by the surface spins in magnetic hollow nanostructures.« less

  7. Coupling Hollow Fe3O4-Fe Nanoparticles with Graphene Sheets for High-Performance Electromagnetic Wave Absorbing Material.

    PubMed

    Qu, Bin; Zhu, Chunling; Li, Chunyan; Zhang, Xitian; Chen, Yujin

    2016-02-17

    We developed a strategy for coupling hollow Fe3O4-Fe nanoparticles with graphene sheets for high-performance electromagnetic wave absorbing material. The hollow Fe3O4-Fe nanoparticles with average diameter and shell thickness of 20 and 8 nm, respectively, were uniformly anchored on the graphene sheets without obvious aggregation. The minimal reflection loss RL values of the composite could reach -30 dB at the absorber thickness ranging from 2.0 to 5.0 mm, greatly superior to the solid Fe3O4-Fe/G composite and most magnetic EM wave absorbing materials recently reported. Moreover, the addition amount of the composite into paraffin matrix was only 18 wt %.

  8. Preparation of fluorescent mesoporous hollow silica-fullerene nanoparticles via selective etching for combined chemotherapy and photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Yang, Yannan; Yu, Meihua; Song, Hao; Wang, Yue; Yu, Chengzhong

    2015-07-01

    Well-dispersed mesoporous hollow silica-fullerene nanoparticles with particle sizes of ~50 nm have been successfully prepared by incorporating fullerene molecules into the silica framework followed by a selective etching method. The fabricated fluorescent silica-fullerene composite with high porosity demonstrates excellent performance in combined chemo/photodynamic therapy.Well-dispersed mesoporous hollow silica-fullerene nanoparticles with particle sizes of ~50 nm have been successfully prepared by incorporating fullerene molecules into the silica framework followed by a selective etching method. The fabricated fluorescent silica-fullerene composite with high porosity demonstrates excellent performance in combined chemo/photodynamic therapy. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02769a

  9. Ag doped hollow TiO2 nanoparticles as an effective green fungicide against Fusarium solani and Venturia inaequalis phytopathogens

    NASA Astrophysics Data System (ADS)

    Sankar Boxi, Siddhartha; Mukherjee, Khushi; Paria, Santanu

    2016-02-01

    Chemical-based pesticides are widely used in agriculture to protect crops from insect infestation and diseases. However, the excessive use of highly toxic pesticides causes several human health (neurological, tumor, cancer) and environmental problems. Therefore nanoparticle-based green pesticides have become of special importance in recent years. The antifungal activities of pure and Ag doped (solid and hollow) TiO2 nanoparticles are studied against two potent phytopathogens, Fusarium solani (which causes Fusarium wilt disease in potato, tomato, etc) and Venturia inaequalis (which causes apple scab disease) and it is found that hollow nanoparticles are more effective than the other two. The antifungal activities of the nanoparticles were further enhanced against these two phytopathogens under visible light exposure. The fungicidal effect of the nanoparticles depends on different parameters, such as particle concentration and the intensity of visible light. The minimum inhibitory dose of the nanoparticles for V. inaequalis and F. solani are 0.75 and 0.43 mg/plate. The presence of Ag as a dopant helps in the formation of stable Ag-S and disulfide bonds (R-S-S-R) in cellular protein, which leads to cell damage. During photocatalysis generated •OH radicals loosen the cell wall structure and this finally leads to cell death. The mechanisms of the fungicidal effect of nanoparticles against these two phytopathogens are supported by biuret and triphenyl tetrazolium chloride analyses and field emission electron microscopy. Apart from the fungicidal effect, at a very low dose (0.015 mg/plate) the nanoparticles are successful in arresting production of toxic napthoquinone pigment for F. solani which is related to the fungal pathogenecity. The nanoparticles are found to be effective in protecting potatoes affected by F. solani or other fungi from spoiling.

  10. Ag doped hollow TiO2 nanoparticles as an effective green fungicide against Fusarium solani and Venturia inaequalis phytopathogens.

    PubMed

    Boxi, Siddhartha Sankar; Mukherjee, Khushi; Paria, Santanu

    2016-02-26

    Chemical-based pesticides are widely used in agriculture to protect crops from insect infestation and diseases. However, the excessive use of highly toxic pesticides causes several human health (neurological, tumor, cancer) and environmental problems. Therefore nanoparticle-based green pesticides have become of special importance in recent years. The antifungal activities of pure and Ag doped (solid and hollow) TiO2 nanoparticles are studied against two potent phytopathogens, Fusarium solani (which causes Fusarium wilt disease in potato, tomato, etc) and Venturia inaequalis (which causes apple scab disease) and it is found that hollow nanoparticles are more effective than the other two. The antifungal activities of the nanoparticles were further enhanced against these two phytopathogens under visible light exposure. The fungicidal effect of the nanoparticles depends on different parameters, such as particle concentration and the intensity of visible light. The minimum inhibitory dose of the nanoparticles for V. inaequalis and F. solani are 0.75 and 0.43 mg/plate. The presence of Ag as a dopant helps in the formation of stable Ag-S and disulfide bonds (R-S-S-R) in cellular protein, which leads to cell damage. During photocatalysis generated (•)OH radicals loosen the cell wall structure and this finally leads to cell death. The mechanisms of the fungicidal effect of nanoparticles against these two phytopathogens are supported by biuret and triphenyl tetrazolium chloride analyses and field emission electron microscopy. Apart from the fungicidal effect, at a very low dose (0.015 mg/plate) the nanoparticles are successful in arresting production of toxic napthoquinone pigment for F. solani which is related to the fungal pathogenecity. The nanoparticles are found to be effective in protecting potatoes affected by F. solani or other fungi from spoiling. PMID:26808118

  11. Ag doped hollow TiO2 nanoparticles as an effective green fungicide against Fusarium solani and Venturia inaequalis phytopathogens.

    PubMed

    Boxi, Siddhartha Sankar; Mukherjee, Khushi; Paria, Santanu

    2016-02-26

    Chemical-based pesticides are widely used in agriculture to protect crops from insect infestation and diseases. However, the excessive use of highly toxic pesticides causes several human health (neurological, tumor, cancer) and environmental problems. Therefore nanoparticle-based green pesticides have become of special importance in recent years. The antifungal activities of pure and Ag doped (solid and hollow) TiO2 nanoparticles are studied against two potent phytopathogens, Fusarium solani (which causes Fusarium wilt disease in potato, tomato, etc) and Venturia inaequalis (which causes apple scab disease) and it is found that hollow nanoparticles are more effective than the other two. The antifungal activities of the nanoparticles were further enhanced against these two phytopathogens under visible light exposure. The fungicidal effect of the nanoparticles depends on different parameters, such as particle concentration and the intensity of visible light. The minimum inhibitory dose of the nanoparticles for V. inaequalis and F. solani are 0.75 and 0.43 mg/plate. The presence of Ag as a dopant helps in the formation of stable Ag-S and disulfide bonds (R-S-S-R) in cellular protein, which leads to cell damage. During photocatalysis generated (•)OH radicals loosen the cell wall structure and this finally leads to cell death. The mechanisms of the fungicidal effect of nanoparticles against these two phytopathogens are supported by biuret and triphenyl tetrazolium chloride analyses and field emission electron microscopy. Apart from the fungicidal effect, at a very low dose (0.015 mg/plate) the nanoparticles are successful in arresting production of toxic napthoquinone pigment for F. solani which is related to the fungal pathogenecity. The nanoparticles are found to be effective in protecting potatoes affected by F. solani or other fungi from spoiling.

  12. Triple-enzyme mimetic activity of nickel-palladium hollow nanoparticles and their application in colorimetric biosensing of glucose.

    PubMed

    Wang, Qingqing; Zhang, Lingling; Shang, Changshuai; Zhang, Zhiquan; Dong, Shaojun

    2016-04-01

    We demonstrate that nickel-palladium hollow nanoparticles (NiPd hNPs) exhibit triple-enzyme mimetic activity: oxidase-like activity, peroxidase-like activity and catalase-like activity. As peroxidase mimetics, the catalytic activity of NiPd hNPs was investigated in detail. On this basis, a simple glucose biosensor with a wide linear range and low detection limit was developed. PMID:27009927

  13. One-pot synthesis of hollow NiSe-CoSe nanoparticles with improved performance for hybrid supercapacitors

    NASA Astrophysics Data System (ADS)

    Chen, Haichao; Fan, Meiqiang; Li, Chao; Tian, Guanglei; Lv, Chunju; Chen, Da; Shu, Kangying; Jiang, Jianjun

    2016-10-01

    Hollow NiSe-CoSe samples have been synthesized for the first time via a one-pot solvothermal approach. The strategy is robust enough to synthesize NiSe-CoSe nanoparticles with different NiSe to CoSe ratios but with a similar hollow structure. Co ions in the NiSe-CoSe nanoparticles play decisive role for formation of the hollow structure; otherwise, the nanoparticles become solid for the NiSe sample. When used as the positive electroactive materials for energy storage, the NiSe-CoSe samples show excellent electrochemical activity in alkaline electrolyte. Using the synergistic effect between NiSe and CoSe, the electrochemical performance of NiSe-CoSe can be tuned by varying the NiSe to CoSe ratios. The NiSe-CoSe sample with a NiSe to CoSe ratio of 4:2 shows the best electrochemical performance in terms of superior specific capacity, improved rate capability and excellent cycling stability. In addition, the electrochemical performance of NiSe-CoSe sample with a NiSe to CoSe ratio of 4:2 is also evaluated via assembling hybrid supercapacitors with RGO, and the hybrid supercapacitor delivers both high power and energy densities (41.8 Wh kg-1 at 750 W kg-1 and 20.3 Wh kg-1 at 30 kW kg-1).

  14. Au/Pd core-shell nanoparticles with varied hollow Au cores for enhanced formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Hsu, Chiajen; Huang, Chienwen; Hao, Yaowu; Liu, Fuqiang

    2013-03-01

    A facile method has been developed to synthesize Au/Pd core-shell nanoparticles via galvanic replacement of Cu by Pd on hollow Au nanospheres. The unique nanoparticles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet-visible spectroscopy, and electrochemical measurements. When the concentration of the Au solution was decreased, grain size of the polycrystalline hollow Au nanospheres was reduced, and the structures became highly porous. After the Pd shell formed on these Au nanospheres, the morphology and structure of the Au/Pd nanoparticles varied and hence significantly affected the catalytic properties. The Au/Pd nanoparticles synthesized with reduced Au concentrations showed higher formic acid oxidation activity (0.93 mA cm-2 at 0.3 V) than the commercial Pd black (0.85 mA cm-2 at 0.3 V), suggesting a promising candidate as fuel cell catalysts. In addition, the Au/Pd nanoparticles displayed lower CO-stripping potential, improved stability, and higher durability compared to the Pd black due to their unique core-shell structures tuned by Au core morphologies.

  15. Au/Pd core-shell nanoparticles with varied hollow Au cores for enhanced formic acid oxidation.

    PubMed

    Hsu, Chiajen; Huang, Chienwen; Hao, Yaowu; Liu, Fuqiang

    2013-03-01

    A facile method has been developed to synthesize Au/Pd core-shell nanoparticles via galvanic replacement of Cu by Pd on hollow Au nanospheres. The unique nanoparticles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet-visible spectroscopy, and electrochemical measurements. When the concentration of the Au solution was decreased, grain size of the polycrystalline hollow Au nanospheres was reduced, and the structures became highly porous. After the Pd shell formed on these Au nanospheres, the morphology and structure of the Au/Pd nanoparticles varied and hence significantly affected the catalytic properties. The Au/Pd nanoparticles synthesized with reduced Au concentrations showed higher formic acid oxidation activity (0.93 mA cm-2 at 0.3 V) than the commercial Pd black (0.85 mA cm-2 at 0.3 V), suggesting a promising candidate as fuel cell catalysts. In addition, the Au/Pd nanoparticles displayed lower CO-stripping potential, improved stability, and higher durability compared to the Pd black due to their unique core-shell structures tuned by Au core morphologies.

  16. Au/Pd core-shell nanoparticles with varied hollow Au cores for enhanced formic acid oxidation

    PubMed Central

    2013-01-01

    A facile method has been developed to synthesize Au/Pd core-shell nanoparticles via galvanic replacement of Cu by Pd on hollow Au nanospheres. The unique nanoparticles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet–visible spectroscopy, and electrochemical measurements. When the concentration of the Au solution was decreased, grain size of the polycrystalline hollow Au nanospheres was reduced, and the structures became highly porous. After the Pd shell formed on these Au nanospheres, the morphology and structure of the Au/Pd nanoparticles varied and hence significantly affected the catalytic properties. The Au/Pd nanoparticles synthesized with reduced Au concentrations showed higher formic acid oxidation activity (0.93 mA cm-2 at 0.3 V) than the commercial Pd black (0.85 mA cm-2 at 0.3 V), suggesting a promising candidate as fuel cell catalysts. In addition, the Au/Pd nanoparticles displayed lower CO-stripping potential, improved stability, and higher durability compared to the Pd black due to their unique core-shell structures tuned by Au core morphologies. PMID:23452438

  17. The influence of pressure and gas flow on size and morphology of titanium oxide nanoparticles synthesized by hollow cathode sputtering

    NASA Astrophysics Data System (ADS)

    Gunnarsson, Rickard; Pilch, Iris; Boyd, Robert D.; Brenning, Nils; Helmersson, Ulf

    2016-07-01

    Titanium oxide nanoparticles have been synthesized via sputtering of a hollow cathode in an argon atmosphere. The influence of pressure and gas flow has been studied. Changing the pressure affects the nanoparticle size, increasing approximately proportional to the pressure squared. The influence of gas flow is dependent on the pressure. In the low pressure regime (107 ≤ p ≤ 143 Pa), the nanoparticle size decreases with increasing gas flow; however, at high pressure (p = 215 Pa), the trend is reversed. For low pressures and high gas flows, it was necessary to add oxygen for the particles to nucleate. There is also a morphological transition of the nanoparticle shape that is dependent on the pressure. Shapes such as faceted, cubic, and cauliflower can be obtained.

  18. Hollow Au-Cu2O Core-Shell Nanoparticles with Geometry-Dependent Optical Properties as Efficient Plasmonic Photocatalysts under Visible Light.

    PubMed

    Lu, Biao; Liu, Aiping; Wu, Huaping; Shen, Qiuping; Zhao, Tingyu; Wang, Jianshan

    2016-03-29

    Hollow Au-Cu2O core-shell nanoparticles were synthesized by using hollow gold nanoparticles (HGNs) as the plasmon-tailorable cores to direct epitaxial growth of Cu2O nanoshells. The effective geometry control of hollow Au-Cu2O core-shell nanoparticles was achieved through adjusting the HGN core sizes, Cu2O shell thicknesses, and morphologies related to structure-directing agents. The morphology-dependent plasmonic band red-shifts across the visible and near-infrared spectral regions were observed from experimental extinction spectra and theoretical simulation based on the finite-difference time-domain method. Moreover, the hollow Au-Cu2O core-shell nanoparticles with synergistic optical properties exhibited higher photocatalytic performance in the photodegradation of methyl orange when compared to pristine Cu2O and solid Au-Cu2O core-shell nanoparticles under visible-light irradiation due to the efficient photoinduced charge separation, which could mainly be attributed to the Schottky barrier and plasmon-induced resonant energy transfer. Such optical tunability achieved through the hollow cores and structure-directed shells is of benefit to the performance optimization of metal-semiconductor nanoparticles for photonic, electronic, and photocatalytic applications. PMID:26954100

  19. Polymer-Coated Hollow Mesoporous Silica Nanoparticles for Triple-Responsive Drug Delivery.

    PubMed

    Zhang, Yuanyuan; Ang, Chung Yen; Li, Menghuan; Tan, Si Yu; Qu, Qiuyu; Luo, Zhong; Zhao, Yanli

    2015-08-19

    In this study, pH, reduction and light triple-responsive nanocarriers based on hollow mesoporous silica nanoparticles (HMSNs) modified with poly(2-(diethylamino)ethyl methacrylate) (PDEAEMA) were developed via surface-initiated atom transfer radical polymerization. Both reduction-cleavable disulfide bond and light-cleavable o-nitrobenzyl ester were used as the linkages between HMSNs and pH-sensitive PDEAEMA polymer caps. A series of characterization techniques were applied to characterize and confirm the structures of the intermediates and final nanocarriers. Doxorubicin (DOX) was easily encapsulated into the nanocarriers with a high loading capacity, and quickly released in response to the stimuli of reducing agent, acid environment or UV light irradiation. In addition, flow cytometry analysis, confocal laser scanning microscopy observations and cytotoxicity studies indicated that the nanocarriers were efficiently internalized by HeLa cancer cells, exhibiting (i) enhanced release of DOX into the cytoplasm under external UV light irradiation, (ii) better cytotoxicity against HeLa cells, and (iii) superior control over drug delivery and release. Thus, the triple-responsive nanocarriers present highly promising potentials as a drug delivery platform for cancer therapy. PMID:26221866

  20. In vivo delivery of bovine viral diahorrea virus, E2 protein using hollow mesoporous silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Mahony, D.; Cavallaro, A. S.; Mody, K. T.; Xiong, L.; Mahony, T. J.; Qiao, S. Z.; Mitter, N.

    2014-05-01

    Our work focuses on the application of mesoporous silica nanoparticles as a combined delivery vehicle and adjuvant for vaccine applications. Here we present results using the viral protein, E2, from bovine viral diarrhoea virus (BVDV). BVDV infection occurs in the target species of cattle and sheep herds worldwide and is therefore of economic importance. E2 is a major immunogenic determinant of BVDV and is an ideal candidate for the development of a subunit based nanovaccine using mesoporous silica nanoparticles. Hollow type mesoporous silica nanoparticles with surface amino functionalisation (termed HMSA) were characterised and assessed for adsorption and desorption of E2. A codon-optimised version of the E2 protein (termed Opti-E2) was produced in Escherichia coli. HMSA (120 nm) had an adsorption capacity of 80 μg Opti-E2 per mg HMSA and once bound E2 did not dissociate from the HMSA. Immunisation studies in mice with a 20 μg dose of E2 adsorbed to 250 μg HMSA was compared to immunisation with Opti-E2 (50 μg) together with the traditional adjuvant Quillaja saponaria Molina tree saponins (QuilA, 10 μg). The humoral responses with the Opti-E2/HMSA nanovaccine although slightly lower than those obtained for the Opti-E2 + QuilA group demonstrated that HMSA particles are an effective adjuvant that stimulated E2-specific antibody responses. Importantly the cell-mediated immune responses were consistently high in all mice immunised with Opti-E2/HMSA nanovaccine formulation. Therefore we have shown the Opti-E2/HMSA nanoformulation acts as an excellent adjuvant that gives both T-helper 1 and T-helper 2 mediated responses in a small animal model. This study has provided proof-of-concept towards the development of an E2 subunit nanoparticle based vaccine.Our work focuses on the application of mesoporous silica nanoparticles as a combined delivery vehicle and adjuvant for vaccine applications. Here we present results using the viral protein, E2, from bovine viral

  1. Fabrication of unique hollow silicate nanoparticles with hierarchically micro/mesoporous shell structure by a simple double template approach.

    PubMed

    Rivera-Virtudazo, R V; Fuji, M; Takai, C; Shirai, T

    2012-12-01

    An innovative type of hollow silicate nanoparticle with a micro/mesoporous shell wall (NSHPMS) was synthesized at room temperature via an eco-friendly double template approach, followed by simple acid reflux. TEM observations of NSHPMSs showed hollow interior nanoparticles (<100 nm) with a wormhole-like shell structure. The nitrogen gas (N(2)) adsorption/desorption isotherm exhibited a unique two-step pattern: the first step (0.2 < P/P(o) < 0.35) signifies the presence of the micro/mesoporous shell wall while the second step (0.85 < P/P(o) < 0.99) represents the void space in between the NSHPMSs. This resulted to an improved specific surface area up to ~2055.5 m(2) g(-1) and a total pore volume as high as ~6.59 cm(3) g(-1) which is better compared with the usual reported data for hollow particles with a mesoporous shell wall. The stable wormhole mesoporous shell wall provided sufficient spaces that contribute to high adsorption capacities and faster adsorption rates. One can envision that larger quantities of framework composition can be obtained using our NSHPMSs.

  2. Fabrication of unique hollow silicate nanoparticles with hierarchically micro/mesoporous shell structure by a simple double template approach

    NASA Astrophysics Data System (ADS)

    Rivera-Virtudazo, R. V.; Fuji, M.; Takai, C.; Shirai, T.

    2012-12-01

    An innovative type of hollow silicate nanoparticle with a micro/mesoporous shell wall (NSHPMS) was synthesized at room temperature via an eco-friendly double template approach, followed by simple acid reflux. TEM observations of NSHPMSs showed hollow interior nanoparticles (<100 nm) with a wormhole-like shell structure. The nitrogen gas (N2) adsorption/desorption isotherm exhibited a unique two-step pattern: the first step (0.2 < P/Po < 0.35) signifies the presence of the micro/mesoporous shell wall while the second step (0.85 < P/Po < 0.99) represents the void space in between the NSHPMSs. This resulted to an improved specific surface area up to ˜2055.5 m2 g-1 and a total pore volume as high as ˜6.59 cm3 g-1 which is better compared with the usual reported data for hollow particles with a mesoporous shell wall. The stable wormhole mesoporous shell wall provided sufficient spaces that contribute to high adsorption capacities and faster adsorption rates. One can envision that larger quantities of framework composition can be obtained using our NSHPMSs.

  3. The deposition of titanium dioxide nanoparticles by means of a hollow cathode plasma jet in dc regime

    NASA Astrophysics Data System (ADS)

    Perekrestov, R.; Kudrna, P.; Tichý, M.

    2015-06-01

    TiO2 nanoparticles are being investigated in this work. Nanoparticles were obtained in Ar plasma on monocrystaline Si(111) substrate by means of a gas-phase deposition using a low pressure hollow cathode plasma jet. The material of the cathode is pure titanium. Oxygen was introduced separately from argon through an inlet in the chamber. The nanoparticle growth mechanism is qualitatively discussed. The morphology of the surfaces of thin films was investigated by an atomic force microscope. The chemical composition of the thin films was investigated by means of an energy-dispersive x-ray analysis and x-ray photoelectron spectroscopy. A cylindrical Langmuir probe and a fiber optic thermometer was used for measurements of plasma parameters and neutral gas temperature respectively. The relationship between plasma parameters and the films’ morphology is particularly explained.

  4. Molecularly imprinted fluorescent hollow nanoparticles as sensors for rapid and efficient detection λ-cyhalothrin in environmental water.

    PubMed

    Wang, Jixiang; Qiu, Hao; Shen, Hongqiang; Pan, Jianming; Dai, Xiaohui; Yan, Yongsheng; Pan, Guoqing; Sellergren, Börje

    2016-11-15

    Molecularly imprinted fluorescent polymers have shown great promise in biological or chemical separations and detections, due to their high stability, selectivity and sensitivity. In this work, molecularly imprinted fluorescent hollow nanoparticles, which could rapidly and efficiently detect λ-cyhalothrin (a toxic insecticide) in water samples, was reported. The molecularly imprinted fluorescent sensor showed excellent sensitivity (the limit of detection low to 10.26nM), rapid detection rate (quantitative detection of λ-cyhalothrin within 8min), regeneration ability (maintaining good fluorescence properties after 8 cycling operation) and appreciable selectivity over several structural analogs. Moreover, the fluorescent sensor was further used to detect λ-cyhalothrin in real samples form the Beijing-Hangzhou Grand Canal Water. Despite the relatively complex components of the environmental water, the molecularly imprinted fluorescent hollow nanosensor still showed good recovery, clearly demonstrating the potential value of this smart sensor nanomaterial in environmental monitoring. PMID:27208472

  5. Sonication-Aided Formation of Hollow Hybrid Nanoparticles as High-Efficiency Absorbents for Dissolved Toluene in Water.

    PubMed

    Huang, Ting; Xu, Liju; Wang, Chen; Yin, Zheng; Qiu, Dong

    2016-01-01

    A surfactant-free emulsion polymerization process was developed to produce hollow hybrid nanoparticles (HHNP thereafter). Ultrasonication was found not only to help the generation of nanosized monomer droplets but also to generate surface active species through mediating the hydrolysis of the monomer, 3-(methacryloyloxy) propyltrimethoxysilane (MPS), thus stabilizing the oil/water interface. The hollow structure was formed based on a soft template approach, where the partially hydrolyzed monomer served as emulsifier and polymerized at the interface to form a hybrid shell. These HHNPs were used to absorb dissolved toluene in water and it was found they could reduce the toluene level down to zero, a level hardly being achieved by other methods. Combined with their good colloidal stability in water, these HHNPs are very promising colloidal collectors for dissolved organic solvents, in order to generate high quality water from contaminated water. PMID:26467238

  6. A novel self-enhanced electrochemiluminescence immunosensor based on hollow Ru-SiO2@PEI nanoparticles for NSE analysis

    NASA Astrophysics Data System (ADS)

    Zhou, Limin; Huang, Jianshe; Yu, Bin; You, Tianyan

    2016-02-01

    Poly(ethylenimine) (PEI) and Ru(bpy)32+-doped silica (Ru-SiO2) nanoparticles were simply mixed together to prepare a novel self-enhanced electrochemiluminescence (ECL) composite of Ru-SiO2@PEI. The hollow Ru-SiO2@PEI nanoparticles were used to build an ECL immunosensor for the analysis of neuron specific enolase (NSE). PEI not only assembled on the surface of Ru-SiO2 nanoparticles through the electrostatic interaction to act as co-reactant for Ru(bpy)32+ ECL, but also provided alkaline condition to etch the Ru-SiO2 nanoparticles to form the hollow Ru-SiO2@PEI nanoparticles with porous shell. The unique structure of the Ru-SiO2@PEI nanoparticles loaded both a large amount of Ru(bpy)32+ and its co-reactant PEI at the same time, which shortened the electron-transfer distance, thereby greatly enhanced the luminous efficiency and amplified the ECL signal. The developed immunosensor showed a wide linear range from 1.0 × 10-11 to 1.0 × 10-5 mg mL-1 with a low detection limit of 1.0 × 10-11 mg mL-1 for NSE. When the immunosensor was used for the determination of NSE in clinical human serum, the results were comparable with those obtained by using enzyme-linked immunosorbent assay (ELISA) method. The proposed method provides a promising alternative for NSE analysis in clinical samples.

  7. A novel self-enhanced electrochemiluminescence immunosensor based on hollow Ru-SiO2@PEI nanoparticles for NSE analysis

    PubMed Central

    Zhou, Limin; Huang, Jianshe; Yu, Bin; You, Tianyan

    2016-01-01

    Poly(ethylenimine) (PEI) and Ru(bpy)32+-doped silica (Ru-SiO2) nanoparticles were simply mixed together to prepare a novel self-enhanced electrochemiluminescence (ECL) composite of Ru-SiO2@PEI. The hollow Ru-SiO2@PEI nanoparticles were used to build an ECL immunosensor for the analysis of neuron specific enolase (NSE). PEI not only assembled on the surface of Ru-SiO2 nanoparticles through the electrostatic interaction to act as co-reactant for Ru(bpy)32+ ECL, but also provided alkaline condition to etch the Ru-SiO2 nanoparticles to form the hollow Ru-SiO2@PEI nanoparticles with porous shell. The unique structure of the Ru-SiO2@PEI nanoparticles loaded both a large amount of Ru(bpy)32+ and its co-reactant PEI at the same time, which shortened the electron-transfer distance, thereby greatly enhanced the luminous efficiency and amplified the ECL signal. The developed immunosensor showed a wide linear range from 1.0 × 10−11 to 1.0 × 10−5 mg mL−1 with a low detection limit of 1.0 × 10−11 mg mL−1 for NSE. When the immunosensor was used for the determination of NSE in clinical human serum, the results were comparable with those obtained by using enzyme-linked immunosorbent assay (ELISA) method. The proposed method provides a promising alternative for NSE analysis in clinical samples. PMID:26916963

  8. Growth of Hollow Transition Metal (Fe, Co, Ni) Oxide Nanoparticles on Graphene Sheets through Kirkendall Effect as Anodes for High-Performance Lithium-Ion Batteries.

    PubMed

    Yu, Xianbo; Qu, Bin; Zhao, Yang; Li, Chunyan; Chen, Yujin; Sun, Chunwen; Gao, Peng; Zhu, Chunling

    2016-01-26

    A general strategy based on the nanoscale Kirkendall effect has been developed to grow hollow transition metal (Fe, Co or Ni) oxide nanoparticles on graphene sheets. When applied as lithium-ion battery anodes, these hollow transition metal oxide-based composites exhibit excellent electrochemical performance, with high reversible capacities and long-term stabilities at a high current density, superior to most transition metal oxides reported to date.

  9. Red-green-blue fluorescent hollow carbon nanoparticles isolated from chromatographic fractions for cellular imaging

    NASA Astrophysics Data System (ADS)

    Gong, Xiaojuan; Hu, Qin; Paau, Man Chin; Zhang, Yan; Shuang, Shaomin; Dong, Chuan; Choi, Martin M. F.

    2014-06-01

    An as-synthesised hollow carbon nanoparticle (HC-NP) sample has been proved to be a relatively complex mixture, and its complexity can be reduced significantly by high-performance liquid chromatography. An unprecedented reduction in such complexity can reveal fractions of HC-NP with unique luminescence properties. While the UV-vis absorption profile for the HC-NP mixture is featureless, the HC-NP fractions do possess unique absorption bands and specific emission wavelengths. The HC-NP fractions are fully anatomised by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry, displaying their fragmentation mass ion features. The shell thickness and crystal lattices of the selected HC-NP fractions are determined as 6.13, 8.31, 2.22, and 8.66 nm, and 0.37, 0.35, 0.33, and 0.32 nm by transmission electron microscopy, respectively. The fractionated HC-NP show profound differences in emission quantum yield, allowing for brighter HC-NP to be isolated from an apparent low quantum yield mixture. Finally, red, green and blue emissive HC-NP are isolated from the as-synthesised HC-NP sample. They show good photostability and have been demonstrated to be excellent probes for cellular imaging.An as-synthesised hollow carbon nanoparticle (HC-NP) sample has been proved to be a relatively complex mixture, and its complexity can be reduced significantly by high-performance liquid chromatography. An unprecedented reduction in such complexity can reveal fractions of HC-NP with unique luminescence properties. While the UV-vis absorption profile for the HC-NP mixture is featureless, the HC-NP fractions do possess unique absorption bands and specific emission wavelengths. The HC-NP fractions are fully anatomised by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry, displaying their fragmentation mass ion features. The shell thickness and crystal lattices of the selected HC-NP fractions are determined as 6.13, 8.31, 2.22, and 8.66 nm, and 0

  10. Asymmetric silica encapsulation toward colloidal Janus nanoparticles: a concave nanoreactor for template-synthesis of an electocatalytic hollow Pt nanodendrite.

    PubMed

    Koo, Jung Hun; Kim, Daun; Kim, Jin Goo; Jeong, Hwakyeung; Kim, Jongwon; Lee, In Su

    2016-08-14

    A novel reverse microemulsion strategy was developed to asymmetrically encapsulate metal-oxide nanoparticles in silica by exploiting the self-catalytic growth of aminosilane-containing silica at a single surface site. This strategy produced various colloidal Janus nanoparticles, including Au/Fe3O4@asy-SiO2, which were converted to an Au-containing silica nanosphere, Au@con-SiO2, by reductive Fe3O4 dissolution. The use of Au@con-SiO2 as a metal-growing nanoreactor allowed the templated synthesis of various noble-metal nanocrystals, including a hollow dendritic Pt nanoshell which exhibits significantly better electrocatalytic activities for the oxygen reduction reaction than commercial Pt/C catalysts. PMID:27432650

  11. Asymmetric silica encapsulation toward colloidal Janus nanoparticles: a concave nanoreactor for template-synthesis of an electocatalytic hollow Pt nanodendrite

    NASA Astrophysics Data System (ADS)

    Koo, Jung Hun; Kim, Daun; Kim, Jin Goo; Jeong, Hwakyeung; Kim, Jongwon; Lee, In Su

    2016-07-01

    A novel reverse microemulsion strategy was developed to asymmetrically encapsulate metal-oxide nanoparticles in silica by exploiting the self-catalytic growth of aminosilane-containing silica at a single surface site. This strategy produced various colloidal Janus nanoparticles, including Au/Fe3O4@asy-SiO2, which were converted to an Au-containing silica nanosphere, Au@con-SiO2, by reductive Fe3O4 dissolution. The use of Au@con-SiO2 as a metal-growing nanoreactor allowed the templated synthesis of various noble-metal nanocrystals, including a hollow dendritic Pt nanoshell which exhibits significantly better electrocatalytic activities for the oxygen reduction reaction than commercial Pt/C catalysts.A novel reverse microemulsion strategy was developed to asymmetrically encapsulate metal-oxide nanoparticles in silica by exploiting the self-catalytic growth of aminosilane-containing silica at a single surface site. This strategy produced various colloidal Janus nanoparticles, including Au/Fe3O4@asy-SiO2, which were converted to an Au-containing silica nanosphere, Au@con-SiO2, by reductive Fe3O4 dissolution. The use of Au@con-SiO2 as a metal-growing nanoreactor allowed the templated synthesis of various noble-metal nanocrystals, including a hollow dendritic Pt nanoshell which exhibits significantly better electrocatalytic activities for the oxygen reduction reaction than commercial Pt/C catalysts. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr03557d

  12. Enhanced Gas Sensing Properties of SnO2 Hollow Spheres Decorated with CeO2 Nanoparticles Heterostructure Composite Materials.

    PubMed

    Liu, Jiangyang; Dai, Mingjun; Wang, Tianshuang; Sun, Peng; Liang, Xishuang; Lu, Geyu; Shimanoe, Kengo; Yamazoe, Noboru

    2016-03-01

    CeO2 decorated SnO2 hollow spheres were successfully synthesized via a two-step hydrothermal strategy. The morphology and structures of as-obtained CeO2/SnO2 composites were analyzed by various kinds of techniques. The SnO2 hollow spheres with uniform size around 300 nm were self-assembled with SnO2 nanoparticles and were hollow with a diameter of about 100 nm. The CeO2 nanoparticles on the surface of SnO2 hollow spheres could be clearly observed. X-ray photoelectron spectroscopy results confirmed the existence of Ce(3+) and the increased amount of both chemisorbed oxygen and oxygen vacancy after the CeO2 decorated. Compared with pure SnO2 hollow spheres, such composites revealed excellent enhanced sensing properties to ethanol. When the ethanol concentration was 100 ppm, the sensitivity of the CeO2/SnO2 composites was 37, which was 2.65-times higher than that of the primary SnO2 hollow spheres. The sensing mechanism of the enhanced gas sensing properties was also discussed.

  13. Ultrafine Pd nanoparticles encapsulated in microporous Co3O4 hollow nanospheres for in situ molecular detection of living cells.

    PubMed

    Xi, Jiangbo; Zhang, Yan; Wang, Ning; Wang, Lin; Zhang, Zheye; Xiao, Fei; Wang, Shuai

    2015-03-11

    Recent progress in the in situ molecular detection of living cells has attracted tremendous research interests due to its great significance in biochemical, physiological, and pathological investigation. Especially for the electrochemical detection of hydrogen peroxide (H2O2) released by living cells, the highly efficient and cost-effective electrocatalysts are highly desirable. In this work, we develop a novel type of microporous Co3O4 hollow nanospheres containing encapsulated Pd nanoparticles (Pd@Co3O4). Owing to the synergy effect between the permeable microporous Co3O4 shell and the ultrafine Pd nanoparticles that encapsulated in it, the resultant Pd@Co3O4 based electrode exhibits excellent electrochemical sensor performance toward H2O2, even when the content of Pd in Pd@Co3O4 hollow nanospheres is as low as 1.14 wt %, which enable it be used for real-time tracking of the secretion of H2O2 in different types of living human cells.

  14. Temperature control of light transmission using mixed system of silica hollow particles with nanoparticle shell and organic components.

    PubMed

    Fujiwara, Masahiro; Shiokawa, Kumi; Monobe, Hirosato; Shimizu, Yo

    2015-01-21

    We reported before that a silica hollow particle whose shell consists of silica nanoparticle (SHP-NP) has a high light reflection ability to prevent light transmission through the particle, which is caused from the intensive light diffusion by the hollow structure and the nanoparticle of the shell. Since the difference in the refractive indices between silica and air is responsible for the strong light reflection, the mixing of the particle with organic components having refractive indices close to that of silica such as tetradecane produced transparent mixtures by suppression of the light reflection. The transparency of the mixtures thus prepared could be controlled by temperature variation. For example, the mixture of the particle SHP-NP with tetradecane was transparent at 20 °C and opaque at 70 °C, while the mixture with n-hexyl cyclohexane was opaque at 20 °C and transparent at 70 °C. As the refractive indices of organic components changed with temperature more than 10 times wider than that of silica, the temperature alternation produced a significant change in the difference of the refractive indices between them to achieve complete control of the transparency of the mixtures. This simple control of the light transmission that can automatically regulate sunlight into the room with temperature alteration is expected to be suitable for smart glass technology for energy conservation. PMID:25536370

  15. Interface-directed self-assembly of gold nanoparticles and fabrication of hybrid hollow capsules by interfacial cross-linking polymerization.

    PubMed

    Tian, Jia; Yuan, Liang; Zhang, Mingming; Zheng, Fan; Xiong, Qingqing; Zhao, Hanying

    2012-06-26

    Amphiphilic gold nanoparticles (AuNPs) were produced at liquid-liquid interface via ligand exchange between hydrophilic AuNPs and disulfide-containing polymer chains. By using oil droplets as templates, hybrid hollow capsules with AuNPs on the surfaces were obtained after interfacial cross-linking polymerization. The volume ratio of toluene to water exerts an important effect on the size of capsules. The average size of the capsules increases with the volume ratio. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM) were used to characterize the hollow structures. In this research, not only one-component but also multicomponent hollow capsules were prepared by copolymerization of acrylamide and hybrid AuNPs at liquid-liquid interface. Because of the improvement in hydrophilicity of the hollow capsules, the average size of multicomponent capsules is bigger than one-component ones in aqueous solution.

  16. Significantly enhanced dye removal performance of hollow tin oxide nanoparticles via carbon coating in dark environment and study of its mechanism

    PubMed Central

    2014-01-01

    Understanding the correlation between physicochemical properties and morphology of nanostructures is a prerequisite for widespread applications of nanomaterials in environmental application areas. Herein, we illustrated that the uniform-sized SnO2@C hollow nanoparticles were large-scale synthesized by a facile hydrothermal method. The size of the core-shell hollow nanoparticles was about 56 nm, and the shell was composed of a solid carbon layer with a thickness of 2 ~ 3 nm. The resulting products were characterized in terms of morphology, composition, and surface property by various analytical techniques. Moreover, the SnO2@C hollow nanoparticles are shown to be effective adsorbents for removing four different dyes from aqueous solutions, which is superior to the pure hollow SnO2 nanoparticles and commercial SnO2. The enhanced mechanism has also been discussed, which can be attributed to the high specific surface areas after carbon coating. PMID:25221462

  17. In vivo and in vitro evaluation of the cytotoxic effects of Photosan-loaded hollow silica nanoparticles on liver cancer

    NASA Astrophysics Data System (ADS)

    Liu, Zhong-Tao; Xiong, Li; Liu, Zhi-Peng; Miao, Xiong-Ying; Lin, Liang-Wu; Wen, Yu

    2014-06-01

    This study aimed to compare the inhibitory effects of photosensitizers loaded in hollow silica nanoparticles and conventional photosensitizers on HepG2 human hepatoma cell proliferation and determine the underlying mechanisms. Photosensitizers (conventional Photosan-II or nanoscale Photosan-II) were administered to in vitro cultured HepG2 hepatoma cells and treated by photodynamic therapy (PDT) with various levels of light exposure. To assess photosensitizers' effects, cell viability was determined by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. In addition, apoptotic and necrotic cells were measured by flow cytometry and the expression of caspase-3 and caspase-9 evaluated by western blot. Finally, the in vivo effects of nanoscale and conventional photosensitizers on liver cancer were assessed in nude mice. Nanoscale Photosan-II significantly inhibited hepatoma cell viability in a concentration-dependent manner and this effect was more pronounced with high laser doses. Moreover, nanoscale photosensitizers performed better than the conventional ones under the same experimental conditions ( p < 0.05). Flow cytometry data demonstrated that laser-induced cell death was markedly increased after treatment with nanoscale Photosan-II in comparison with free Photosan-II ( p < 0.05). Activated caspase-3 and caspase-9 levels were significantly higher in cells treated with Photosan-II loaded in silica nanoparticles than free Photosan-II ( p < 0.05). Accordingly, treatment with nanoscale photosensitizers resulted in improved outcomes (tumor volume) in a mouse model of liver cancer, in comparison with conventional photosensitizers. Hollow silica nanoparticles containing photosensitizer more efficiently inhibited hepatoma cells than photosensitizer alone, through induction of apoptosis, both in vivo and in vitro.

  18. The Ru complex and hollow gold nanoparticles branched-hydrogel as signal probe for construction of electrochemiluminescent aptasensor.

    PubMed

    Gui, Guo-Feng; Zhuo, Ying; Chai, Ya-Qin; Xiang, Yun; Yuan, Ruo

    2016-03-15

    In this work, a novel Ru complex and hollow gold nanoparticles branched-poly(N-(3-aminopropyl)methacrylamide) hydrogel composites (pNAMA-Ru-HGNPs) were prepared and used as electrogenerated chemiluminescence (ECL) signal probe to construct aptasensor for ultrasensitive detection of thrombin (TB). Herein, [Ru(phen)2(cpaphen)](2+) linked N-(3-aminopropyl)methacrylamide and hollow gold nanoparticles functionalized N-(3-aminopropyl)methacrylamide were used as two polymer monomers to prepare pNAMA-Ru-HGNPs composites via free-radical polymerization. The obtained hydrogel composite, containing amount of Ru complex and HGNPs, were used as effective tag-carriers for the immobilization of thrombin binding aptamer II (TBA II) to form the pNAMA-Ru-HGNPs labeled TBA II (pNAMA-Ru-HGNPs-TBA II). For building the interface of the aptasensor, dendritic gold nanoparticles reduced by poly(ethyleneimine) (PEI@DGNPs) were modified on the carbon nanotube-nafion (CNTs-Nf) coated electrode through electrostatic adsorption, which was used not only as matrix for immobilization of thrombin binding aptamer I (TBA I) but also as enhancer to amplify the ECL signal because PEI is an efficient co-reactant of Ru complex. Target TB was sandwiched between pNAMA-Ru-HGNPs-TBA II and TBA I, resulting in the ECL signals relevant to the TB concentrations. Combining the novel pNAMA-Ru-HGNPs containing amount of Ru complex as the ECL signal probe and PEI@DGNPs as the enhancer for signal amplification, the sandwich ECL aptasensor was constructed for the detection of TB with a wide range of 1.0 fM to 10 pM and a low detection of 0.54 fM. PMID:26385731

  19. Facile synthesis of monodisperse of hollow mesoporous SiO2 nanoparticles and in-situ growth of Ag nanoparticles for antibacterial.

    PubMed

    Xu, Peng; Liang, Juan; Cao, Xiaoyong; Tang, Jingen; Gao, Juan; Wang, Liying; Shao, Wei; Gao, Qinwei; Teng, Zhaogang

    2016-07-15

    Monodispersed hollow mesoporous silica nanoparticles (HMSNs) are successfully synthesized via a facile dual template method, in which poly(styrene-co-methyl methacrylate-co-methacrylic acid) (PS-PMMA-PMAA) particles are used as hard template for producing the hollow structure and cetyltrimethylammonium bromide (CTAB) used for introducing the mesopores in the silica shells. The obtained HMSNs possess uniform diameter and morphology, and the shell of which could be adjusted by changing the addition of silicon precursor. The synthesized HMSNs have been characterized by transmission electron microscopy (TEM) and nitrogen physisorption. Furthermore, the HMSNs are used as support for in-situ deposition of silver nanoparticles (Ag NPs) using n-butylamine as reducing agent for AgNO3 in ethanol. Significantly, Ag NPs were successfully supported in the HMSNs without any aggregation. The Ag-deposited HMSNs showed excellent dispersibility in ethanol and water, and their antibacterial activity against Escherichia coli (E. coli) ATCC 25922 and Staphylococcus aureus (S. aureus) ATCC 6538 have been demonstrated. Therefore, the unique nanostructure based on the HMSNs provided a useful platform for the fabrication of antibacterial agent with superior activity and accessibility. And also, it is expected to be a significant template for the synthesis of other novel nanostructures. PMID:27115332

  20. Cytotoxicity of folic acid conjugated hollow silica nanoparticles toward Caco2 and 3T3 cells, with and without encapsulated DOX.

    PubMed

    Patel, Kunal; Sundara Raj, Behin; Chen, Yan; Lou, Xia

    2016-04-01

    Hollow silica nanoparticles of two sizes with and without a folic acid targeting ligand were synthesized. Fickian diffusion of the antitumor drug doxorubicin hydrochloride (DOX) was demonstrated by the produced nanoparticles, achieving a cumulative release of 73% and 45% for 215 nm and 430 nm particles respectively over a period of 500 h. The hollow silica nanoparticles presented a time and dose dependent toxicity, selective to human epithelial colorectal adenocarcinoma (Caco2) cells, over mouse embryonic fibroblast (3T3) cells. At 24h Caco2 cell viability was reduced to 66% using pure hollow silica at a concentration of 50 μg mL(-1), while that of 3T3 cells remained at 94% under the same conditions. The selective cytotoxicity of hollow silica nanoparticles was further enhanced by conjugation of folic acid and incorporation of DOX: at 24h and an equivalent DOX concentration of 0.5 μg mL(-1), viable Caco2 cells were reduced to 45% while 3T3 cells were reduced to 83%. Interestingly the equivalent dose of free DOX was more toxic to 3T3 than to Caco2 cells, reducing the 3T3 viability to 72% and the Caco2 viability to 80%, which is likely due to the presence of the p-glycoprotein pumps in Caco2 cells. Folic acid conjugation served to enhance the viability of both cell lines in this work. Careful optimization of the folate content should further improve the cell specificity of the hollow silica nanoparticles, thus providing a viable targeting platform for cancer therapy.

  1. Preparation of iron aluminate (FeAl2O4) nanoparticles from FeAl2O4 hollow particles fabricated by using a spray pyrolysis process

    NASA Astrophysics Data System (ADS)

    Yun, Jaecheol; Kim, Yangdo; Park, Dahee; Yun, Jung-Yeul

    2015-05-01

    Iron aluminate (FeAl2O4) hollow particles with a spinel structure were synthesized by using a spray pyrolysis process. FeAl2O4 hollow particles were formed at a reaction temperature of 900 °C at a flow rate of 40 L/min as a result of the rapid solvent evaporation and decomposition gases from the droplets in the spray solution prepared from metal salts and organic reagents. FeAl2O4 hollow particles were fabricated at a reaction temperature of 900 °C with a flow rate of 40 L/min. The FeAl2O4 hollow particles were heat treated for 3 hours at 600 °C in a 5% H2/Ar atmosphere to form the crystal particles. Subsequently, FeAl2O4 nanoparticles were fabricated from the FeAl2O4 hollow particles by using the wet milling process. After milling for 60 minutes, transmission electron microscopy revealed the FeAl2O4 particles to have a mean size of approximately 50 nm. The FeAl2O4 nanoparticles were fabricated successfully by using a two-step process, spray pyrolysis and wet milling.

  2. The Effect of Scattering Layer on the Performance of Dye-Sensitized Solar Cells Using TiO2 Hollow Spheres/TiO2 Nanoparticles Films as Photoanodes.

    PubMed

    Park, Su Kyung; Suh, Soong-Hyuck; Lee, Min Woo; Yun, Tae Kwan; Bae, Jae Young

    2015-10-01

    TiO2 hollow spheres were successfully synthesized using poly styrene as the template. Dye-sensitized solar cells are fabricated based on double-layered composite films of TiO2 nanoparticles and TiO2 hollow spheres. The photoelectric conversion performances of Dye-sensitized solar cells based on TiO2 nanoparticles/TiO2 nanoparticles, TiO2 nanoparticles/TiO2 hollow spheres and TiO2 hollow spheres/TiO2 hollow spheres double-layered films are investigated, and their photoelectric conversion efficiencies were determined to 4.52, 7.10 and 5.48%, respectively. Dye-sensitized solar cells based on double layered composite films of TiO2 nanoparticles and TiO2 hollow spheres exhibit the highest photo-electric conversion efficiency mainly due to the combined effect of two factors, the high light scattering of over-layer hollow spheres that enhance harvesting light of the Dye-sensitized solar cells and the under-layer TiO2 nanoparticle layer that ensures good electronic contact between TiO2 film and FTO conducting glass. The double layered composite TiO2 film electrodes are a promising development in enhancing the performance of dye-sensitized solar cells.

  3. The Effect of Scattering Layer on the Performance of Dye-Sensitized Solar Cells Using TiO2 Hollow Spheres/TiO2 Nanoparticles Films as Photoanodes.

    PubMed

    Park, Su Kyung; Suh, Soong-Hyuck; Lee, Min Woo; Yun, Tae Kwan; Bae, Jae Young

    2015-10-01

    TiO2 hollow spheres were successfully synthesized using poly styrene as the template. Dye-sensitized solar cells are fabricated based on double-layered composite films of TiO2 nanoparticles and TiO2 hollow spheres. The photoelectric conversion performances of Dye-sensitized solar cells based on TiO2 nanoparticles/TiO2 nanoparticles, TiO2 nanoparticles/TiO2 hollow spheres and TiO2 hollow spheres/TiO2 hollow spheres double-layered films are investigated, and their photoelectric conversion efficiencies were determined to 4.52, 7.10 and 5.48%, respectively. Dye-sensitized solar cells based on double layered composite films of TiO2 nanoparticles and TiO2 hollow spheres exhibit the highest photo-electric conversion efficiency mainly due to the combined effect of two factors, the high light scattering of over-layer hollow spheres that enhance harvesting light of the Dye-sensitized solar cells and the under-layer TiO2 nanoparticle layer that ensures good electronic contact between TiO2 film and FTO conducting glass. The double layered composite TiO2 film electrodes are a promising development in enhancing the performance of dye-sensitized solar cells. PMID:26726506

  4. Voltage-Gated Transport of Nanoparticles across Free-Standing All-Carbon-Nanotube-Based Hollow-Fiber Membranes.

    PubMed

    Wei, Gaoliang; Quan, Xie; Chen, Shuo; Fan, Xinfei; Yu, Hongtao; Zhao, Huimin

    2015-07-15

    Understanding the mechanism underlying controllable transmembrane transport observed in biological membranes benefits the development of next-generation separation membranes for a variety of important applications. In this work, on the basis of common structural features of cell membranes, a very simple biomimetic membrane system exhibiting gated transmembrane performance has been constructed using all-carbon-nanotube (CNT)-based hollow-fiber membranes. The conductive CNT membranes with hydrophobic pore channels can be positively or negatively charged and are consequently capable of regulating the transport of nanoparticles across their pore channels by their "opening" or "closing". The switch between penetration and rejection of nanoparticles through/by CNT membranes is of high efficiency and especially allows dynamic control. The underlying mechanism is that CNT pore channels with different polarities can prompt or prevent the formation of their noncovalent interactions with charged nanoparticles, resulting in their rejection or penetration by/through the CNT membranes. The theory about noncovalent interactions and charged pore channels may provide new insight into understanding the complicated ionically and bimolecularly gated transport across cell membranes and can contribute to many other important applications beyond the water purification and resource recovery demonstrated in this study. PMID:26103999

  5. TiO2 nanoparticle detection by means of laser beam scattering in a hollow cathode plasma jet

    NASA Astrophysics Data System (ADS)

    Perekrestov, R.; Kudrna, P.; Tichý, M.; Khalakhan, I.; Myshkin, V. F.

    2016-07-01

    The distribution of TiO2 nanoparticles in a plasma plume of a hollow cathode plasma jet is being studied in this work. The method is based on the detection of light from a laser beam scattered on nanoparticles by three detectors: a photodiode, an optical spectrometer and a digital photo camera. The Rayleigh–Mie theory was used as a basis for the description of the results. Two lasers with wavelengths of 446 and 661 nm were used as light sources. 2D maps of the scattered light intensity were assembled from photo camera pictures at different discharge parameters. Dependencies of the signal intensity on the O2 flow rate and wavelength are discussed. Direct measurements of particle size on the substrate were carried out by means of a scanning electron microscope in order to verify the agreement of results with the theory. Aside from nanoparticles we detected TiO2 columnar structures in the deposited samples. Crystalline structure of the samples was investigated using x-ray diffraction analysis.

  6. Hollow PDA-Au nanoparticles-enabled signal amplification for sensitive nonenzymatic colorimetric immunodetection of carbohydrate antigen 125.

    PubMed

    Zhao, Yan; Zheng, Yiqun; Zhao, Caiyun; You, Jinmao; Qu, Fengli

    2015-09-15

    A novel colorimetric immunoassay was designed for the sensitive detection of carbohydrate antigen 125 (CA125). The success of this immunoassay relies on the use of hollow polydopamine-gold nanoparticles (PDA-Au) for signal amplification to achieve sensitive nonenzymatic colorimetric detection. In particular, PDA-Au was used as a stable and sensitive label and aminated-Fe3O4 magnetic nanoparticles (Fe3O4 NPs) were employed to immobilize capture antibody (Ab1) and acted as a separable immunosensing probe. PDA-Au exhibited high catalytic performance towards p-nitrophenol reduction and thus resulted in significant color change and UV/vis signal variations. The immunoassay was performed based on sandwich protocol. As compared to pure Au nanoparticles, the signal amplification and sensitivity of PDA-Au-based assay was significantly improved. For instance, the dynamic range of the developed colorimetric immunoassay for CA125 was 0.1-100 U/mL with a detection limit of 0.1 U/mL at S/N=3. In addition, this immunoassay was also tested for the analysis of clinical serum samples, which demonstrated its potential for practical diagnostic applications.

  7. Voltage-Gated Transport of Nanoparticles across Free-Standing All-Carbon-Nanotube-Based Hollow-Fiber Membranes.

    PubMed

    Wei, Gaoliang; Quan, Xie; Chen, Shuo; Fan, Xinfei; Yu, Hongtao; Zhao, Huimin

    2015-07-15

    Understanding the mechanism underlying controllable transmembrane transport observed in biological membranes benefits the development of next-generation separation membranes for a variety of important applications. In this work, on the basis of common structural features of cell membranes, a very simple biomimetic membrane system exhibiting gated transmembrane performance has been constructed using all-carbon-nanotube (CNT)-based hollow-fiber membranes. The conductive CNT membranes with hydrophobic pore channels can be positively or negatively charged and are consequently capable of regulating the transport of nanoparticles across their pore channels by their "opening" or "closing". The switch between penetration and rejection of nanoparticles through/by CNT membranes is of high efficiency and especially allows dynamic control. The underlying mechanism is that CNT pore channels with different polarities can prompt or prevent the formation of their noncovalent interactions with charged nanoparticles, resulting in their rejection or penetration by/through the CNT membranes. The theory about noncovalent interactions and charged pore channels may provide new insight into understanding the complicated ionically and bimolecularly gated transport across cell membranes and can contribute to many other important applications beyond the water purification and resource recovery demonstrated in this study.

  8. A one-pot synthetic approach to prepare palladium nanoparticles embedded hierarchically porous TiO{sub 2} hollow spheres for hydrogen peroxide sensing

    SciTech Connect

    Kong Lirong; Lu Xiaofeng; Bian Xiujie; Zhang Wanjin; Wang Ce

    2010-10-15

    A simple one-step method to fabricate hierarchically porous TiO{sub 2}/Pd composite hollow spheres without any template was developed by using solvothermal treatment. Pd nanoparticles (2-5 nm) were well dispersed in the mesopores of the TiO{sub 2} hollow spheres via in-situ reduction. In our experiment, polyvinylpyrrolidone played an important role in the synthetic process as the reducing agent and the connective material between TiO{sub 2} and Pd nanoparticles. HF species generated from solvothermal reaction leaded to the formation of TiO{sub 2} hollow spheres and Ostwald ripening was another main factor that affected the size and structure of the hollow spheres. The as-prepared TiO{sub 2}/Pd composite hollow spheres exhibited high electrocatalytic activity towards the reduction of H{sub 2}O{sub 2}. The sensitivity was about 226.72 {mu}A mM{sup -1} cm{sup -2} with a detection limit of 3.81 {mu}M at a signal-to-noise ratio of 3. These results made the hierarchically porous TiO{sub 2}/Pd composite a promising platform for fabricating new nonenzymic biosensors. - Graphical Abstract: A new one-step solvothermal method was developed to prepare Pd nanoparticles embedded hierarchically porous TiO{sub 2} hollow spheres. Due to its unique nanostructure, the prepared TiO{sub 2}/Pd modified GC electrode exhibit a high sensitivity (226.72 {mu}A mM{sup -1} cm{sup -2}), a relatively low reduction potential (-0.2 V), a fast response time (<3 s) and a relatively low detection limit of 3.81 {mu}M (S/N=3) towards H{sub 2}O{sub 2}.

  9. Preparation and characterization of hollow glass microspheres coated by CoFe{sub 2}O{sub 4} nanoparticles using urea as precipitator via coprecipitation method

    SciTech Connect

    Pang Xiaofen; Fu Wuyou; Yang Haibin Zhu Hongyang; Xu Jing; Li Xiang; Zou Guangtian

    2009-02-04

    The composite of hollow glass microspheres coated by CoFe{sub 2}O{sub 4} nanoparticles has been successfully prepared using urea as precipitator via coprecipitation method. The resultant composites were characterized by X-ray diffraction, field emission scanning electron microscope and vibrating sample magnetometer. The results showed that the slow decomposition of urea could be beneficial to form uniform and entire cobalt ferrite coating layer on the surface of hollow glass microspheres. The smoothest morphology was obtained for the sample prepared from 0.7 M urea, while the sample prepared from 1.0 M urea had the thickest shell. This indicated that there was a competition between the morphology and thickness of the coated microspheres. A possible formation mechanism of hollow glass microspheres coated with cobalt ferrite was proposed. The magnetic properties of the samples were also investigated.

  10. Impacts of surface spins and inter-particle interactions on the magnetism of hollow γ-Fe{sub 2}O{sub 3} nanoparticles

    SciTech Connect

    Khusrhid, Hafsa E-mail: phanm@usf.edu Nemati Porshokouh, Zohreh; Phan, Manh-Huong E-mail: phanm@usf.edu Mukherjee, Pritish; Srikanth, Hariharan E-mail: phanm@usf.edu

    2014-05-07

    A comparative study of the static and dynamic magnetic properties of polycrystalline hollow γ-Fe{sub 2}O{sub 3} nanoparticles with two distinctly different sizes of 10.3 ± 1.3 nm and 14.8 ± 0.5 nm has been performed. High-resolution TEM images confirmed the crystalline structure and the presence of the shell thickness of 2.17 ± 0.28 nm and 3.25 ± 0.24 nm for the 10 nm and 15 nm particles, respectively. Quantitative fits of the frequency dependent ac susceptibility to the Vogel-Fulcher model, τ = τ{sub o} exp[E{sub a}/k(T − T{sub o})], show stronger inter-particle interactions in the 15 nm nanoparticles than in the 10 nm nanoparticles. A systematic analysis of the room-temperature magnetic loops using the modified Langevin function indicates a stronger effect of disordered surface spins in the 10 nm hollow particles as compared to the 15 nm hollow particles. Our study suggests that while the effect of disordered surface spins dominates the magnetic behavior of the 10 nm hollow particles, both the disordered surface spins and inter-particle interactions contribute to the magnetism of the 15 nm hollow particles.

  11. Spin-glass-like freezing of inner and outer surface layers in hollow γ-Fe2O3 nanoparticles

    SciTech Connect

    Khurshid, Hafsa; Lampen-Kelley, Paula; Iglesias, Òscar; Alonso, Javier; Phan, Manh-Huong; Sun, Cheng-Jun; Saboungi, Marie-Louise; Srikanth, Hariharan

    2015-10-27

    Disorder among surface spins largely dominates the magnetic response of ultrafine magnetic particle systems. In this work, we examine time-dependent magnetization in high-quality, monodisperse hollow maghemite nanoparticles (NPs) with a 14.8±0.5 nm outer diameter and enhanced surface-to-volume ratio. The nanoparticle ensemble exhibits spin-glass-like signatures in dc magnetic aging and memory protocols and ac magnetic susceptibility. The dynamics of the system slow near 50 K, and becomes frozen on experimental time scales below 20 K. Remanence curves indicate the development of magnetic irreversibility concurrent with the freezing of the spin dynamics. A strong exchange-bias effect and its training behavior point to highly frustrated surface spins that rearrange much more slowly than interior spins with bulk coordination. Monte Carlo simulations of a hollow particle reproducing the experimental morphology corroborate strongly disordered surface layers with complex energy landscapes that underlie both glass-like dynamics and magnetic irreversibility. Calculated hysteresis loops reveal that magnetic behavior is not identical at the inner and outer surfaces, with spins at the outer surface layer of the 15 nm hollow particles exhibiting a higher degree of frustration. Lastly, our combined experimental and simulated results shed light on the origin of spin-glass-like phenomena and the important role played by the surface spins in magnetic hollow nanostructures.

  12. Kinetic description of metal nanocrystal oxidation: a combined theoretical and experimental approach for determining morphology and diffusion parameters in hollow nanoparticles by the nanoscale Kirkendall effect

    NASA Astrophysics Data System (ADS)

    Watanabe, Yoshiki; Mowbray, Ryan W.; Rice, Katherine P.; Stoykovich, Mark P.

    2014-10-01

    The oxidation of colloidal metal nanocrystals to form hollow shells via the nanoscale Kirkendall effect has been investigated using a combined theoretical and experimental approach. A generalized kinetic model for the formation of hollow nanoparticles describes the phenomenon and, unlike prior models, is applicable to any material system and accounts for the effect of surface energies. Phase diagrams of the ultimate oxidized nanoparticle morphology and the time to achieve complete oxidation are calculated, and are found to depend significantly upon consideration of surface energy effects that destabilize the initial formation of small voids. For the oxidation of Cu nanocrystals to Cu2O nanoparticles, we find that the diffusion coefficients dictate the morphological outcomes: the ratio of ? to ? controls the void size, ? determines the time of oxidation and ? is largely irrelevant in the kinetics of oxidation. The kinetic model was used to fit experimental measurements of 11 nm diameter Cu nanocrystals oxidized in air from which temperature-dependent diffusivities of ? and ? for 100 ≤ T ≤ 200 °C were determined. In contrast to previous interpretations of the nanoscale Kirkendall effect in the Cu/Cu2O system, these results are obtained without any a priori assumptions about the relative magnitudes of ? and ?. The theoretical and experimental approaches presented here are broadly applicable to any nanoparticle system undergoing oxidation, and can be used to precisely control the final nanoparticle morphology for applications in catalysis or optical materials.

  13. Photodynamic effect of photosensitizer-loaded hollow silica nanoparticles for hepatobiliary malignancies: an in vitro and in vivo study

    NASA Astrophysics Data System (ADS)

    Deng, Xiaofeng; Xiong, Li; Wen, Yu; Liu, Zhongtao; Pei, Dongni; Huang, Yaxun; Miao, Xiongying

    2014-03-01

    Background and aims: Nanoparticles have been explored recently as an efficient delivery system for photosensitizers in photodynamic therapy. In this study, polyhematoporphyrin (C34H38N4NaO5,) was loaded into hollow silica nanoparticles (HSNP) by one-step wet chemical-based synthetic route. We evaluate the efficacy and safety of polyhematoporphyrin-loaded HSNP with hepatobiliary malignant cells and in vivo models. Methods: Human liver cancer, cholangiocarcinoma and gallbladder cancer cells were cultured with the HSNP and cellular viability was determined by MTT assay. Apoptotic and necrotic cells were measured by flow cytometry. Finally, we investigate its effect in vivo. Results: In MTT assay, the cell viability of QBC939, Huh-7, GBC-SD and HepG2 cells of the HSNP was 6.4+/-1.3%, 6.5+/-1.2%, 3.7+/-1.2% and 4.7+/-2.0%, respectively, which were significant different from that of free polyhematoporphyrin 62.4+/-4.7%, 62.5+/-6.0%, 33.4+/-6.5% and 44.3+/-1.9%. Flow cytometry demonstrated the laser-induced cell death with polyhematoporphyrin-loaded HSNP was much more severe. Similarly, in vivo results of each kind of cell revealed 14 days post-photoradiated, tumor sizes of the HSNP group were significantly smaller. Administration of the HSNP without illumination cannot cause killing effect both in vitro and in vivo experiments. Conclusions: HSNP is a desirable delivery system in photodynamic therapy for hepatobiliary malignacies, with improved aqueous solubility, stability and transport efficiency of photosensitizers.

  14. Highly sensitive SERS-based immunoassay of aflatoxin B1 using silica-encapsulated hollow gold nanoparticles.

    PubMed

    Ko, Juhui; Lee, Chankil; Choo, Jaebum

    2015-03-21

    Aflatoxin B1 (AFB1) is a well-known carcinogenic contaminant in foods. It is classified as an extremely hazardous compound because of its potential toxicity to the human nervous system. AFB1 has also been extensively used as a biochemical marker to evaluate the degree of food spoilage. In this study, a novel surface-enhanced Raman scattering (SERS)-based immunoassay platform using silica-encapsulated hollow gold nanoparticles (SEHGNs) and magnetic beads was developed for highly sensitive detection of AFB1. SEHGNs were used as highly stable SERS-encoding nano tags, and magnetic beads were used as supporting substrates for the high-density loading of immunocomplexes. Quantitative analysis of AFB1 was performed by monitoring the intensity change of the characteristic peaks of Raman reporter molecules. The limit of detection (LOD) of AFB1, determined by this SERS-based immunoassay, was determined to be 0.1 ng/mL. This method has some advantages over other analytical methods with respect to rapid analysis (less than 30 min), good selectivity, and reproducibility. The proposed method is expected to be a new analytical tool for the trace analysis of various mycotoxins. PMID:25462866

  15. Highly sensitive SERS-based immunoassay of aflatoxin B1 using silica-encapsulated hollow gold nanoparticles.

    PubMed

    Ko, Juhui; Lee, Chankil; Choo, Jaebum

    2015-03-21

    Aflatoxin B1 (AFB1) is a well-known carcinogenic contaminant in foods. It is classified as an extremely hazardous compound because of its potential toxicity to the human nervous system. AFB1 has also been extensively used as a biochemical marker to evaluate the degree of food spoilage. In this study, a novel surface-enhanced Raman scattering (SERS)-based immunoassay platform using silica-encapsulated hollow gold nanoparticles (SEHGNs) and magnetic beads was developed for highly sensitive detection of AFB1. SEHGNs were used as highly stable SERS-encoding nano tags, and magnetic beads were used as supporting substrates for the high-density loading of immunocomplexes. Quantitative analysis of AFB1 was performed by monitoring the intensity change of the characteristic peaks of Raman reporter molecules. The limit of detection (LOD) of AFB1, determined by this SERS-based immunoassay, was determined to be 0.1 ng/mL. This method has some advantages over other analytical methods with respect to rapid analysis (less than 30 min), good selectivity, and reproducibility. The proposed method is expected to be a new analytical tool for the trace analysis of various mycotoxins.

  16. Hollow-spherical Co/N-C nanoparticle as an efficient electrocatalyst used in air cathode microbial fuel cell.

    PubMed

    Yang, Tingting; Li, Kexun; Pu, Liangtao; Liu, Ziqi; Ge, Baochao; Pan, Yajun; Liu, Ying

    2016-12-15

    The hollow-spherical Co/N-C nanoparticle, which is synthesized via a simple hydrothermal reaction followed by heat treatment, is firstly used as electrocatalyst for oxygen reduction reaction (ORR) in air-cathode microbial fuel cell (MFC). The maximum power density of MFC with 10% Co/N-C air-cathode is as high as 2514±59mWm(-2), which is almost 174% higher than the control. The exchange current density (i0) of cathode equipped with 10% Co/N-C is 238% higher than that of untreated AC. While the total resistance of treated samples decreases from 13.017 to 10.255Ω. The intensity ratio of Raman D to G band (ID/IG) decreases from 0.93 (N-C) to 0.73 (Co/N-C), indicating the catalyst forms graphite structure. Both XRD and XPS testify that Co is bonded to N within graphitic sheets and serves as the active sites in ORR. The four-electron pathway of the Co/N-C also plays a crucial role in electrochemical catalytic activity. As a result, it can be expected that the as-synthesized Co/N-C, with extraordinary electro-catalytic performance towards ORR, will be a promising alternative to the state-of-the-art non-precious metal ORR electro-catalysts for electrochemical energy applications.

  17. MOF-Derived Hollow Co9 S8 Nanoparticles Embedded in Graphitic Carbon Nanocages with Superior Li-Ion Storage.

    PubMed

    Liu, Jun; Wu, Chao; Xiao, Dongdong; Kopold, Peter; Gu, Lin; van Aken, Peter A; Maier, Joachim; Yu, Yan

    2016-05-01

    Novel electrode materials consisting of hollow cobalt sulfide nanoparticles embedded in graphitic carbon nanocages (HCSP⊂GCC) are facilely synthesized by a top-down route applying room-temperature synthesized Co-based zeolitic imidazolate framework (ZIF-67) as the template. Owing to the good mechanical flexibility and pronounced structure stability of carbon nanocages-encapsulated Co9 S8 , the as-obtained HCSP⊂GCC exhibit superior Li-ion storage. Working in the voltage of 1.0-3.0 V, they display a very high energy density (707 Wh kg(-1) ), superior rate capability (reversible capabilities of 536, 489, 438, 393, 345, and 278 mA h g(-1) at 0.2, 0.5, 1, 2, 5, and 10C, respectively), and stable cycling performance (≈26% capacity loss after long 150 cycles at 1C with a capacity retention of 365 mA h g(-1) ). When the work voltage is extended into 0.01-3.0 V, a higher stable capacity of 1600 mA h g(-1) at a current density of 100 mA g(-1) is still achieved.

  18. IgA response and protection following nasal vaccination of chickens with Newcastle disease virus DNA vaccine nanoencapsulated with Ag@SiO2 hollow nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhao, Kai; Rong, Guangyu; Hao, Yan; Yu, Lu; Kang, Hong; Wang, Xin; Wang, Xiaohua; Jin, Zheng; Ren, Zhiyu; Li, Zejun

    2016-05-01

    Newcastle disease caused by ND virus (NDV) is a highly contagious disease of birds. Vaccine for effective protection of poultry animals from NDV infection is urgently needed. Mucosal immunity plays a very important role in the antiviral immune response. In this study, a NDV F gene-containing DNA vaccine encapsulated in Ag@SiO2 hollow nanoparticles (pFDNA-Ag@SiO2-NPs) with an average diameter of 500 nm were prepared to assess the mucosal immune response. These nanoparticles exhibited low cytotoxicity and did not destroy the bioactivity of plasmid DNA, which could be expressed in vitro. The plasmid DNA was sustainably released after an initial burst release. In vivo immunization showed that the intranasal immunization of chickens with pFDNA-Ag@SiO2-NPs induced high titers of serum antibody, significantly promoted lymphocyte proliferation and induced higher expression levels of IL-2 and IFN-γ in a dose-dependent manner. These results indicated that the Ag@SiO2 hollow nanoparticles could serve as an efficient and safe delivery carrier for NDV DNA vaccine to induce mucosal immunity. This study has provided promising results for the further development of mucosal vaccines encapsulated in inorganic nanoparticles.

  19. IgA response and protection following nasal vaccination of chickens with Newcastle disease virus DNA vaccine nanoencapsulated with Ag@SiO2 hollow nanoparticles.

    PubMed

    Zhao, Kai; Rong, Guangyu; Hao, Yan; Yu, Lu; Kang, Hong; Wang, Xin; Wang, Xiaohua; Jin, Zheng; Ren, Zhiyu; Li, Zejun

    2016-01-01

    Newcastle disease caused by ND virus (NDV) is a highly contagious disease of birds. Vaccine for effective protection of poultry animals from NDV infection is urgently needed. Mucosal immunity plays a very important role in the antiviral immune response. In this study, a NDV F gene-containing DNA vaccine encapsulated in Ag@SiO2 hollow nanoparticles (pFDNA-Ag@SiO2-NPs) with an average diameter of 500 nm were prepared to assess the mucosal immune response. These nanoparticles exhibited low cytotoxicity and did not destroy the bioactivity of plasmid DNA, which could be expressed in vitro. The plasmid DNA was sustainably released after an initial burst release. In vivo immunization showed that the intranasal immunization of chickens with pFDNA-Ag@SiO2-NPs induced high titers of serum antibody, significantly promoted lymphocyte proliferation and induced higher expression levels of IL-2 and IFN-γ in a dose-dependent manner. These results indicated that the Ag@SiO2 hollow nanoparticles could serve as an efficient and safe delivery carrier for NDV DNA vaccine to induce mucosal immunity. This study has provided promising results for the further development of mucosal vaccines encapsulated in inorganic nanoparticles. PMID:27170532

  20. Surfaces and their effect on the magnetic properties of polycrystalline hollow γ-Mn2O3 and MnO nanoparticles

    NASA Astrophysics Data System (ADS)

    Bah, Mohamed A.; Jaffari, G. Hassnain; Khan, F. A.; Shah, S. Ismat

    2016-07-01

    Manganese oxide nanoparticles were prepared in an inert gas condensation system. X-ray Diffraction (XRD) studies revealed presence of multiple manganese oxide phases while high resolution transmission electron microscopy (HRTEM) showed polycrystalline hollow nanoparticle morphology. The additional inner surface of the hollow nanoparticle directly affect the magnetic properties of these particles. Combined physical structure, electronic structure and magnetic susceptibility analyses led to the conclusion that the prepared nanoparticles are polycrystalline and composed of γ-Mn2O3 and MnO crystallites. Magnetic study found a sharp peak around 38 K with no frequency dependence in the AC susceptibility measurement. Large coercivity (HC) and exchange bias (HEB) fields, up to 11 kOe and 7 kOe, respectively, were observed below the order temperatures. HC and HEB were found to increase and decrease, respectively, as a function of cooling field. Both HC and HEB were found to decrease monotonically as the temperature approached paramagnetic phase transition of the ferrimagnetic component.

  1. IgA response and protection following nasal vaccination of chickens with Newcastle disease virus DNA vaccine nanoencapsulated with Ag@SiO2 hollow nanoparticles

    PubMed Central

    Zhao, Kai; Rong, Guangyu; Hao, Yan; Yu, Lu; Kang, Hong; Wang, Xin; Wang, Xiaohua; Jin, Zheng; Ren, Zhiyu; Li, Zejun

    2016-01-01

    Newcastle disease caused by ND virus (NDV) is a highly contagious disease of birds. Vaccine for effective protection of poultry animals from NDV infection is urgently needed. Mucosal immunity plays a very important role in the antiviral immune response. In this study, a NDV F gene-containing DNA vaccine encapsulated in Ag@SiO2 hollow nanoparticles (pFDNA-Ag@SiO2-NPs) with an average diameter of 500 nm were prepared to assess the mucosal immune response. These nanoparticles exhibited low cytotoxicity and did not destroy the bioactivity of plasmid DNA, which could be expressed in vitro. The plasmid DNA was sustainably released after an initial burst release. In vivo immunization showed that the intranasal immunization of chickens with pFDNA-Ag@SiO2-NPs induced high titers of serum antibody, significantly promoted lymphocyte proliferation and induced higher expression levels of IL-2 and IFN-γ in a dose-dependent manner. These results indicated that the Ag@SiO2 hollow nanoparticles could serve as an efficient and safe delivery carrier for NDV DNA vaccine to induce mucosal immunity. This study has provided promising results for the further development of mucosal vaccines encapsulated in inorganic nanoparticles. PMID:27170532

  2. Dual layer hollow fiber PVDF ultra-filtration membranes containing Ag nano-particle loaded zeolite with longer term anti-bacterial capacity in salt water.

    PubMed

    Shi, Huyan; Xue, Lixin; Gao, Ailin; Zhou, Qingbo

    2016-01-01

    Dual layer polyvinylidene fluoride (PVDF), antibacterial, hollow fiber, ultra-filtration composite membranes with antibacterial particles (silver (Ag) nano-particles loaded zeolite (Z-Ag)) in the outer layer were prepared with high water flux and desired pore sizes. The amounts of Ag(+) released from the composite membranes, freshly made and stored in water and salt solution, were measured. The result indicated that dual layer PVDF antibacterial hollow fiber containing Z-Ag (M-1-Ag) still possessed the ability of continuous release of Ag(+) even after exposure to water with high ionic content, showing a longer term resistance to bacterial adhesion and antibacterial activity than membrane doped with Z-Ag(+) (M-1). Results from an anti-adhesion and bacteria killing test with Escherichia coli supported that the antibacterial efficiency of dual hollow fiber PVDF membranes with Z-Ag was much higher than those with Z-Ag(+) after long time storage in water or exposure to phosphate buffered saline (PBS) solution. This novel hollow fiber membrane may find applications in constructing sea water pretreatment devices with long term antifouling capability for the desalination processes.

  3. Dual layer hollow fiber PVDF ultra-filtration membranes containing Ag nano-particle loaded zeolite with longer term anti-bacterial capacity in salt water.

    PubMed

    Shi, Huyan; Xue, Lixin; Gao, Ailin; Zhou, Qingbo

    2016-01-01

    Dual layer polyvinylidene fluoride (PVDF), antibacterial, hollow fiber, ultra-filtration composite membranes with antibacterial particles (silver (Ag) nano-particles loaded zeolite (Z-Ag)) in the outer layer were prepared with high water flux and desired pore sizes. The amounts of Ag(+) released from the composite membranes, freshly made and stored in water and salt solution, were measured. The result indicated that dual layer PVDF antibacterial hollow fiber containing Z-Ag (M-1-Ag) still possessed the ability of continuous release of Ag(+) even after exposure to water with high ionic content, showing a longer term resistance to bacterial adhesion and antibacterial activity than membrane doped with Z-Ag(+) (M-1). Results from an anti-adhesion and bacteria killing test with Escherichia coli supported that the antibacterial efficiency of dual hollow fiber PVDF membranes with Z-Ag was much higher than those with Z-Ag(+) after long time storage in water or exposure to phosphate buffered saline (PBS) solution. This novel hollow fiber membrane may find applications in constructing sea water pretreatment devices with long term antifouling capability for the desalination processes. PMID:27148717

  4. Seaweed-Derived Route to Fe2O3 Hollow Nanoparticles/N-Doped Graphene Aerogels with High Lithium Ion Storage Performance.

    PubMed

    Liu, Long; Yang, Xianfeng; Lv, Chunxiao; Zhu, Aimei; Zhu, Xiaoyi; Guo, Shaojun; Chen, Chengmeng; Yang, Dongjiang

    2016-03-23

    We developed a nanoscale Kirkendall effect assisted method for simple and scalable synthesis of three-dimensional (3D) Fe2O3 hollow nanoparticles (NPs)/graphene aerogel through the use of waste seaweed biomass as new precursors. The Fe2O3 hollow nanoparticles with an average shell thickness of ∼6 nm are distributed on 3D graphene aerogel, and also act as spacers to make the separation of the neighboring graphene nanosheets. The graphene-Fe2O3 aerogels exhibit high rate capability (550 mA h g(-1) at 5 A g(-1)) and excellent cyclic stability (729 mA h g(-1) at 0.1 A g(-1) for 300 cycles), outperforming all of the reported Fe2O3/graphene hybrid electrodes, due to the hollow structure of the active Fe2O3 NPs and the unique structure of the 3D graphene aerogel framework. The present work represents an important step toward high-level control of high-performance 3D graphene-Fe-based NPs aerogels for maximizing lithium storage with new horizons for important fundamental and technological applications. PMID:26943285

  5. Well-dispersed platinum nanoparticles supported on hierarchical nitrogen-doped porous hollow carbon spheres with enhanced activity and stability for methanol electrooxidation

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Ma, Li; Gan, Mengyu; Yang, Fangfang; Fu, Shenna; Li, Xiao

    2015-08-01

    Hierarchical nitrogen-doped porous hollow carbon spheres (HNPHCS) with porous-thin mesoporous shell and hollow macroporous core structure have been prepared via in-situ oxidation polymerization method using polyaniline as the precursor. After carbonization at 900 °C, the average diameter of HNPHCS is ca. 140 nm with shell thickness of ∼1 nm. Pt nanoparticles with high dispersion and small size have been successfully deposited on the HNPHCS by a microwave-assisted polyol process to synthesize Pt/HNPHCS catalyst. The obtained samples are characterized by physical characterization and electrochemical measurements. Electrochemical studies reveal that the prepared Pt/HNPHCS catalyst possesses notably higher catalytic activity and CO-tolerance, and better stability toward methanol electrooxidation in comparison with Pt/nitrogen-doped porous carbon and the commercial Pt/C catalysts. It is likely that enhanced catalytic properties of the Pt/HNPHCS could be due to the high dispersion of small Pt nanoparticles, the presence of nitrogen species, developed porous-thin mesoporous shell and hollow macroporous core structure of support HNPHCS. As a result, the as-developed Pt/HNPHCS present attractive advantages for the application in fuel cell electrocatalyst.

  6. Interaction Induced High Catalytic Activities of CoO Nanoparticles Grown on Nitrogen-Doped Hollow Graphene Microspheres for Oxygen Reduction and Evolution Reactions

    NASA Astrophysics Data System (ADS)

    Jiang, Zhong-Jie; Jiang, Zhongqing

    2016-06-01

    Nitrogen doped graphene hollow microspheres (NGHSs) have been used as the supports for the growth of the CoO nanoparticles. The nitrogen doped structure favors the nucleation and growth of the CoO nanoparticles and the CoO nanoparticles are mostly anchored on the quaternary nitrogen doped sites of the NGHSs with good monodispersity since the higher electron density of the quaternary nitrogen favors the nucleation and growth of the CoO nanoparticles through its coordination and electrostatic interactions with the Co2+ ions. The resulting NGHSs supported CoO nanoparticles (CoO/NGHSs) are highly active for the oxygen reduction reaction (ORR) with activity and stability higher than the Pt/C and for the oxygen evolution reaction (OER) with activity and stability comparable to the most efficient catalysts reported to date. This indicates that the CoO/NGHSs could be used as efficient bi-functional catalysts for ORR and OER. Systematic analysis shows that the superior catalytic activities of the CoO/NGHSs for ORR and OER mainly originate from the nitrogen doped structure of the NGHSs, the small size of the CoO nanoparticles, the higher specific and electroactive surface area of the CoO/NGHSs, the good electric conductivity of the CoO/NGHSs, the strong interaction between the CoO nanoparticles and the NGHSs, etc.

  7. Interaction Induced High Catalytic Activities of CoO Nanoparticles Grown on Nitrogen-Doped Hollow Graphene Microspheres for Oxygen Reduction and Evolution Reactions

    PubMed Central

    Jiang, Zhong-Jie; Jiang, Zhongqing

    2016-01-01

    Nitrogen doped graphene hollow microspheres (NGHSs) have been used as the supports for the growth of the CoO nanoparticles. The nitrogen doped structure favors the nucleation and growth of the CoO nanoparticles and the CoO nanoparticles are mostly anchored on the quaternary nitrogen doped sites of the NGHSs with good monodispersity since the higher electron density of the quaternary nitrogen favors the nucleation and growth of the CoO nanoparticles through its coordination and electrostatic interactions with the Co2+ ions. The resulting NGHSs supported CoO nanoparticles (CoO/NGHSs) are highly active for the oxygen reduction reaction (ORR) with activity and stability higher than the Pt/C and for the oxygen evolution reaction (OER) with activity and stability comparable to the most efficient catalysts reported to date. This indicates that the CoO/NGHSs could be used as efficient bi-functional catalysts for ORR and OER. Systematic analysis shows that the superior catalytic activities of the CoO/NGHSs for ORR and OER mainly originate from the nitrogen doped structure of the NGHSs, the small size of the CoO nanoparticles, the higher specific and electroactive surface area of the CoO/NGHSs, the good electric conductivity of the CoO/NGHSs, the strong interaction between the CoO nanoparticles and the NGHSs, etc. PMID:27255562

  8. Ultrafast magnetization dynamics of cobalt nanoparticles and individual ferromagnetic dots

    NASA Astrophysics Data System (ADS)

    Bigot, Jean-Yves

    2009-03-01

    The ultrafast magnetization dynamics of magnetic materials can be investigated using femtosecond laser pulses to perform femtosecond magneto-optical Kerr and Faraday measurements [1]. In this talk, we will focus on the magnetization dynamics of cobalt nanoparticles which are either ferromagnetic or super-paramagnetic at room temperature and on the dynamics of individual ferromagnetic dots. In the first case (Co nanoparticles), we will demonstrate that the magnetization dynamics preceding the fluctuations over the anisotropy energy barrier is coherent but exhibits a strongly damped precession [2]. These results, which have been obtained with a three dimensional analysis of the magnetization vector [3] will be discussed in the context of the N'eel-Brown models involving the gyromagnetic character of the magnetization. We will also examine the dynamics of self-organized supra-crystals of cobalt nanoparticles [4]. In the second case, we will present the ultrafast magnetization dynamics of individual ferromagnetic dots (CoPt3, Permalloy, Nickel) made either by e-beam lithography or induced optically on thin films deposited on sapphire and glass substrates. The technique employed is the magneto-optical pump probe imaging (MOPPI) which allows performing time resolved magneto-optical Kerr images with with spatial and temporal resolutions of 300 nm and 150 fs [5]. The study of the demagnetization of the dots for different laser intensities shows that it is possible to write and read ultrafast monodomains on thin films. [3pt] [1] E. Beaurepaire, J.-C. Merle, A. Daunois, J.-Y. Bigot Phys. Rev. Lett., 76, 4250 (1996) [0pt] [2] L.H.F. Andrade, A. Laraoui, M. Vomir, D. Muller, J.-P. Stoquert, C. Estournès, E. Beaurepaire, J.-Y. Bigot Phys. Rev. Lett. 97, 127401 (2006). [0pt] [3] M. Vomir, L. H.F. Andrade, L. Guidoni, E. Beaurepaire, J.-Y. Bigot Phys. Rev. Lett. 94, 237601 (2005). [0pt] [4] I. Lisiecki, V. Halt'e, C. Petit, M.-P. Pileni, J.-Y. Bigot Adv. Mater., 20, 4176 (2008

  9. Hollow and Concave Nanoparticles via Preferential Oxidation of the Core in Colloidal Core/Shell Nanocrystals

    PubMed Central

    2014-01-01

    Hollow and concave nanocrystals find applications in many fields, and their fabrication can follow different possible mechanisms. We report a new route to these nanostructures that exploits the oxidation of Cu2–xSe/Cu2–xS core/shell nanocrystals with various etchants. Even though the Cu2–xSe core is encased in a thick Cu2–xS shell, the initial effect of oxidation is the creation of a void in the core. This is rationalized in terms of diffusion of Cu+ ions and electrons from the core to the shell (and from there to the solution). Differently from the classical Kirkendall effect, which entails an imbalance between in-diffusion and out-diffusion of two different species across an interface, the present mechanism can be considered as a limiting case of such effect and is triggered by the stronger tendency of Cu2–xSe over Cu2–xS toward oxidation and by fast Cu+ diffusion in copper chalcogenides. As the oxidation progresses, expansion of the inner void erodes the entire Cu2–xSe core, accompanied by etching and partial collapse of the shell, yielding Cu2–xSySe1–y concave particles. PMID:24866716

  10. Surface-specific deposition of catalytic metal nanocrystals on hollow carbon nanospheres via galvanic replacement reactions of carbon-encapsulated MnO nanoparticles.

    PubMed

    Lee, Dong-Gyu; Kim, Soo Min; Jeong, Hwakyeung; Kim, Jongwon; Lee, In Su

    2014-05-27

    This paper reports the findings of our efforts toward gaining a more complete understanding and utilization of galvanic replacement reactions involving manganese oxide with noble metals. It was revealed that the site of metal deposition is significantly affected by the variable oxidation state of manganese oxide. The use of carbon-encapsulated MnO nanoparticles as a reaction template led to metal growth specifically on the outermost surfaces of the carbon shells rather than on the MnO cores, which allowed for the selective decoration of the external surfaces of hollow carbon nanospheres with catalytic nanocrystals of various noble metals, including Pt, Pd, Rh, and Ir. By rearranging the sequence between carbon-shell coating and galvanic replacement processes, the deposited metal nanocrystals could be placed on the interior surfaces of hollow carbon nanospheres and, moreover, separately on the internal and the external surfaces, which may enable the respective control of the catalytic functionalities of each specific surface.

  11. SiO(2) /TiO(2) hollow nanoparticles decorated with Ag nanoparticles: enhanced visible light absorption and improved light scattering in dye-sensitized solar cells.

    PubMed

    Hwang, Sun Hye; Shin, Dong Hoon; Yun, Juyoung; Kim, Chanhoi; Choi, Moonjung; Jang, Jyongsik

    2014-04-01

    Hollow SiO2 /TiO2 nanoparticles decorated with Ag nanoparticles (NPs) of controlled size (Ag@HNPs) were fabricated in order to enhance visible-light absorption and improve light scattering in dye-sensitized solar cells (DSSCs). They exhibited localized surface plasmon resonance (LSPR) and the LSPR effects were significantly influenced by the size of the Ag NPs. The absorption peak of the LSPR band dramatically increased with increasing Ag NP size. The LSPR of the large Ag NPs mainly increased the light absorption at short wavelengths, whereas the scattering from the SiO2 /TiO2 HNPs improved the light absorption at long wavelengths. This enabled the working electrode to use the full solar spectrum. Furthermore, the SiO2 layer thickness was adjusted to maximize the LSPR from the Ag NPs and avoid corrosion of the Ag NPs by the electrolyte. Importantly, the power conversion efficiency (PCE) increased from 7.1 % with purely TiO2 -based DSSCs to 8.1 % with HNP-based DSSCs, which is an approximately 12 % enhancement and can be attributed to greater light scattering. Furthermore, the PCEs of Ag@HNP-based DSSCs were 11 % higher (8.1 vs. 9.0 %) than the bare-HNP-based DSSCs, which can be attributed to LSPR. Together, the PCE of Ag@HNP-based DSSCs improved by a total of 27 %, from 7.1 to 9.0 %, due to these two effects. This comparative research will offer guidance in the design of multifunctional nanomaterials and the optimization of solar-cell performance.

  12. Kinetics of self-assembled monolayer formation on individual nanoparticles.

    PubMed

    Smith, Jeremy G; Jain, Prashant K

    2016-08-24

    Self-assembled monolayer (SAM) formation of alkanethiols on nanoparticle surfaces is an extensively studied surface reaction. But the nanoscale aspects of the rich microscopic kinetics of this reaction may remain hidden due to ensemble-averaging in colloidal samples, which is why we investigated in real-time how alkanethiol SAMs form on a single Ag nanoparticle. From single-nanoparticle trajectories obtained using in situ optical spectroscopy, the kinetics of SAM formation appears to be limited by the growth of the layer across the nanoparticle surface. A significant spread in the growth kinetics is seen between nanoparticles. The single-nanoparticle rate distributions suggest two distinct modes for SAM growth: spillover of adsorbed thiols from the initial binding sites on the nanoparticle and direct adsorption of thiol from solution. At low concentrations, wherein direct adsorption from solution is not prevalent and growth takes place primarily by adsorbate migration, the SAM formation rate was less variable from one nanoparticle to another. On the other hand, at higher thiol concentrations, when both modes of growth were operative, the population of nanoparticles with inherent variations in surface conditions and/or morphology exhibited a heterogeneous distribution of rates. These new insights into the complex dynamics of SAM formation may inform synthetic strategies for ligand passivation and functionalization of nanoparticles and models of reactive adsorption and catalysis on nanoparticles. PMID:27523488

  13. A multi-amplification aptasensor for highly sensitive detection of thrombin based on high-quality hollow CoPt nanoparticles decorated graphene.

    PubMed

    Wang, Yan; Yuan, Ruo; Chai, Yaqin; Yuan, Yali; Bai, Lijuan; Liao, Yuhong

    2011-12-15

    In this work, we have successfully demonstrated a facile strategy to incorporate high-quality hollow CoPt bimetal alloy nanoparticles (HCoPt) onto reduced graphene oxide sheet (HCoPt-RGs). An advanced sandwich-type electrochemical aptasensor for thrombin was proposed by using the HCoPt-RGs conjugates as secondary label. The formed conjugates provided large surface area for loading plentiful redox probe thionine (Thi), horseradish peroxidase (HRP) and secondary aptamer (Apt II) with good stability and friendly biocompatibility, indicating their superior properties in electroactive mediator enrichment and biomolecule immobilization. Furthermore, activated by glutaraldehyde (GA), the chitosan-hollow CoPt alloy nanoparticle (CS-HCoPt) film can greatly facilitate the capture of primary aptamer (Apt I) and dramatically reduce the nonspecific binding. Excellent sensitivity was obtained by detecting the conspicuously enhanced electrochemical signal of Thi, which was amplified by HCoPt alloy nanoparticles and HRP toward the catalytic reduction of H(2)O(2). The aptasensor displayed excellent performance for thrombin with a wide linearity in the range from 1.0×10(-12) to 5.0×10(-8) M and a relatively low detection limit of 3.4×10(-13) M. Moreover, the resulted aptasensor also exhibited good specificity, acceptable reproducibility and stability, indicating that the present strategy could pave a promising way for the wide application of graphene in clinical research. PMID:21944185

  14. Magnetic and Mössbauer spectroscopy studies of hollow microcapsules made of silica-coated CoFe2O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Lyubutin, I. S.; Gervits, N. E.; Starchikov, S. S.; Lin, Chun-Rong; Tseng, Yaw-Teng; Shih, Kun-Yauh; Wang, Cheng-Chien; Chen, I.-Han; Ogarkova, Yu L.; Korotkov, N. Yu

    2016-01-01

    The hollow microcapsules made of silica-coated CoFe2O4 nanoparticles were synthesized using chemical co-precipitation, followed by the sol-gel method. Poly(MMA-co-MAA) microspheres were used as a core template which can be completely removed after annealing at 450 °C. The microcapsules are monodisperse with the outer diameter of about 450 nm and the thickness of the shell is about 50 nm. The nanoparticles of Co-ferrite are single crystalline. The size of the nanoparticles and magnetic properties of CoFe2O4/SiO2 hollow spheres can be tuned with high accuracy at the annealing stage. The Mössbauer data indicate that CoFe2O4 ferrite is an inverse spinel, in which Fe3+ and Co2+ ions are distributed in both octahedral and tetrahedral sites with the inversion degree close to the bulk ferrite value. At low temperature the CoFe2O4/SiO2 nanoparticles are in antiferromagnetic (AFM) state due to the canted or triangular magnetic structure. Under heating in the applied field, AFM structure transforms to the ferrimagnetic (FM) structure, that increases the magnetization. The Mössbauer data revealed that the small size CoFe2O4/SiO2 particles do not show superparamagnetic behavior, but they transit to the paramagnetic state by the jump-like first order magnetic transition (JMT). This effect is a specific property of the magnetic nanoparticles isolated by inert material. The suggested method of synthesis can be modified with various bio-ligands on the silane surface, and such materials can find many applications in diagnostics and bio-separation.

  15. One-shot deep-UV pulsed-laser-induced photomodification of hollow metal nanoparticles for high-density data storage on flexible substrates.

    PubMed

    Wan, Dehui; Chen, Hsuen-Li; Tseng, Shao-Chin; Wang, Lon A; Chen, Yung-Pin

    2010-01-26

    In this paper, we report a new optical data storage method: photomodification of hollow gold nanoparticle (HGN) monolayers induced by one-shot deep-ultraviolet (DUV) KrF laser recording. As far as we are aware, this study is the first to apply HGNs in optical data storage and also the first to use a recording light source for the metal nanoparticles (NPs) that is not a surface plasmon resonance (SPR) wavelength. The short wavelength of the recording DUV laser improved the optical resolution dramatically. We prepared HGNs exhibiting two absorbance regions: an SPR peak in the near-infrared (NIR) region and an intrinsic material extinction in the DUV region. A single pulse from a KrF laser heated the HGNs and transformed them from hollow structures to smaller solid spheres. This change in morphology for the HGNs was accompanied by a significant blue shift of the SPR peak. Employing this approach, we demonstrated its patterning ability with a resolving power of a half-micrometer (using a phase mask) and developed a readout method (using a blue-ray laser microscope). Moreover, we prepared large-area, uniform patterns of monolayer HGNs on various substrates (glass slides, silicon wafers, flexible plates). If this spectral recording technique could be applied onto thin flexible tapes, the recorded data density would increase significantly relative to that of current rigid discs (e.g., compact discs).

  16. Na-ion Storage Performances of FeSex and Fe2O3 Hollow Nanoparticles-Decorated Reduced Graphene Oxide Balls prepared by Nanoscale Kirkendall Diffusion Process

    NASA Astrophysics Data System (ADS)

    Park, Gi Dae; Cho, Jung Sang; Lee, Jung-Kul; Kang, Yun Chan

    2016-02-01

    Uniquely structured FeSex-reduced graphene oxide (rGO) composite powders, in which hollow FeSex nanoparticles are uniformly distributed throughout the rGO matrix, were prepared by spray pyrolysis applying the nanoscale Kirkendall diffusion process. Iron oxide-rGO composite powders were transformed into FeSex-rGO composite powders by a two-step post-treatment process. Metallic Fe nanocrystals formed during the first-step post-treatment process were transformed into hollow FeSex nanoparticles during the selenization process. The FeSex-rGO composite powders had mixed crystal structures of FeSe and FeSe2 phases. A rGO content of 33% was estimated from the TG analysis of the FeSex-rGO composite powders. The FeSex-rGO composite powders had superior sodium-ion storage properties compared to those of the Fe2O3-rGO composite powders with similar morphological characteristics. The discharge capacities of the FeSex- and Fe2O3-rGO composite powders for the 200th cycle at a constant current density of 0.3 A g‑1 were 434 and 174 mA h g‑1, respectively. The FeSex-rGO composite powders had a high discharge capacity of 311 mA h g‑1 for the 1000th cycle at a high current density of 1 A g‑1.

  17. Fluorometric sensing of ultralow As(III) concentrations using Ag doped hollow CdS/ZnS bi-layer nanoparticles.

    PubMed

    Boxi, Siddhartha Sankar; Paria, Santanu

    2015-12-21

    Arsenic poisoning from drinking water has been an important global issue in recent years. Because of the high level toxicity of arsenic to human health, an easy, inexpensive, low level and highly selective detection technique is of great importance to take any early precautions. This study reports the synthesis of Ag doped hollow CdS/ZnS bi-layer (Ag-h-CdS/ZnS) nanoparticles for the easy fluorometric determination of As(iii) ions in the aqueous phase. The hollow bi-layer structures were synthesized by a sacrificial core method using AgBr as the sacrificial core and the core was removed by dissolution in an ammonium hydroxide solution. The synthesized nanoparticles were characterized using different instrumental techniques. A good linear relationship was obtained between fluorescence quenching intensity and As(iii) concentration in the range of 0.75-22.5 μg L(-1) at neutral pH with a limit of detection as low as 0.226 μg L(-1). PMID:26541652

  18. Synthesis and characterization of bioactive conjugated near-infrared fluorescent proteinoid-poly(L-lactic acid) hollow nanoparticles for optical detection of colon cancer

    PubMed Central

    Kolitz-Domb, Michal; Corem-Salkmon, Enav; Grinberg, Igor; Margel, Shlomo

    2014-01-01

    Colon cancer is one of the major causes of death in the Western world. Early detection significantly improves long-term survival for patients with colon cancer. Near-infrared (NIR) fluorescent nanoparticles are promising candidates for use as contrast agents for tumor detection. Using NIR offers several advantages for bioimaging compared with fluorescence in the visible spectrum: lower autofluorescence of biological tissues and lower absorbance and, consequently, deeper penetration into biomatrices. The present study describes the preparation of new NIR fluorescent proteinoid-poly(L-lactic acid) (PLLA) nanoparticles. For this purpose, a P(EF-PLLA) random copolymer was prepared by thermal copolymerization of L-glutamic acid (E) with L-phenylalanine (F) and PLLA. Under suitable conditions, this proteinoid-PLLA copolymer can self-assemble to nanosized hollow particles of relatively narrow size distribution. This self-assembly process was used for encapsulation of the NIR dye indocyanine green. The encapsulation process increases significantly the photostability of the dye. These NIR fluorescent nanoparticles were found to be stable and nontoxic. Leakage of the NIR dye from these nanoparticles into phosphate-buffered saline containing 4% human serum albumin was not detected. Tumor-targeting ligands such as peanut agglutinin and anticarcinoembryonic antigen antibodies were covalently conjugated to the surface of the NIR fluorescent P(EF-PLLA) nanoparticles, thereby increasing the fluorescent signal of tumors with upregulated corresponding receptors. Specific colon tumor detection by the NIR fluorescent P(EF-PLLA) nanoparticles was demonstrated in a chicken embryo model. In future work, we plan to extend this study to a mouse model, as well as to encapsulate a cancer drug such as doxorubicin within these nanoparticles for therapeutic applications. PMID:25382975

  19. Nanoparticle imaging. 3D structure of individual nanocrystals in solution by electron microscopy.

    PubMed

    Park, Jungwon; Elmlund, Hans; Ercius, Peter; Yuk, Jong Min; Limmer, David T; Chen, Qian; Kim, Kwanpyo; Han, Sang Hoon; Weitz, David A; Zettl, A; Alivisatos, A Paul

    2015-07-17

    Knowledge about the synthesis, growth mechanisms, and physical properties of colloidal nanoparticles has been limited by technical impediments. We introduce a method for determining three-dimensional (3D) structures of individual nanoparticles in solution. We combine a graphene liquid cell, high-resolution transmission electron microscopy, a direct electron detector, and an algorithm for single-particle 3D reconstruction originally developed for analysis of biological molecules. This method yielded two 3D structures of individual platinum nanocrystals at near-atomic resolution. Because our method derives the 3D structure from images of individual nanoparticles rotating freely in solution, it enables the analysis of heterogeneous populations of potentially unordered nanoparticles that are synthesized in solution, thereby providing a means to understand the structure and stability of defects at the nanoscale. PMID:26185247

  20. A novel platform for high sensitivity determination of PbP2a based on gold nanoparticles composited graphitized mesoporous carbon and doxorubicin loaded hollow gold nanospheres.

    PubMed

    Yang, Juan; Shen, Huawei; Zhang, Xing; Tao, Yiyi; Xiang, Hua; Xie, Guoming

    2016-03-15

    Gold nanoparticles composite graphitized mesoporous carbon nanoparticles (GMCs@AuNPs) biocomposite with the signal amplification capability was successfully synthesized for use in an immunoassay for penicillin binding protein 2 a (PbP2a). The polyamidoamine (PAMAM) dendrimers were first electrodeposited onto the Au electrode can greatly increase the amount of the captured antibodies. Protein A was used to properly orientate immobilized antibody against PbP2a, which strongly improved specificity of the antigen-antibody binding. Hollow gold nanospheres (HGNPs) as effective nanocarriers have been synthesized by sacrificial galvanic replacement of cobalt nanoparticles capable of encapsulating doxorubicin (Dox). The obtained HGNPs@Dox bionanocomposite was used for further loading of detection antibody (Ab2) to form the HGNPs@Dox@Ab2 bioconjugate. Then, the differential pulse voltammetric signals related to the concentration of PbP2a for Dox could be detected, and the immunosensor exhibited a detection limit as low as 0.65 pg mL(-1) (at an S/N ratio of 3). The proposed method with an excellent differentiation ability showed high sensitivity and specificity. The morphologies and electrochemistry properties of the composites were investigated by scanning electron microscopy, electrochemical characterization, UV-visible absorption spectroscopy, fluorescence spectrophotometer and Malvern laser particle size analyzer, respectively. In addition, the basic approach described here would be applicable towards developing biodetection assays against other important targets. Moreover, the bioconjugate of HGNPs@Dox is also a promising pattern to delivery Dox in vivo for anticancer therapy.

  1. Fabrication of barium- and strontium-doped silica/titania hollow nanoparticles and their synergetic effects on promoting neuronal differentiation by activating ERK and p38 pathways.

    PubMed

    Kim, Sojin; Jang, Yoonsun; Oh, Wan-Kyu; Kim, Chanhoi; Jang, Jyongsik

    2014-07-01

    Pristine, barium-doped, and strontium-doped hollow nanoparticles (p-HNPs, Ba-HNP, and Sr-HNP; HNPs) are prepared by sonication-mediated etching and redeposition (SMER) method and alkali-earth-metal hydroxide solution treatment. The HNPs are investigated to facilitate synergetic neuronal differentiation through alkali-earth-metal doping and in conjunction with nerve growth factor (NGF). PC12 cells are used as model cells for neuronal differentiation. The differentiation efficiency is improved in the presence of the HNPs+NGF, and the neurite length is in the order of Sr-HNP+NGF > Ba-HNP+NGF > p-HNP+NGF > NGF. Silica/titania have increasing effect on both differentiation efficiency and neurite length, and doped barium/strontium influences additional elongation of the average neurite length. Take advantage of hollow structure, NGF is encapsulated into HNPs, and they are further applied for directly inducing differentiation. The maximum differentiation efficiency is 67% in presence of the NGF-encapsulated Sr-HNP, which was 1.3 times higher than previous research. Furthermore, the neurite length is also 2.7 times higher than MnO2 decorated poly(3,4-ethylenedioxythiophene) nanoellipsoids. Ba- and Sr-HNP may offer a possibility for novel application of metal-hybrid nanomaterials for cell differentiation, and can be expanded to other cellular applications.

  2. Polypyrrole-enveloped Pd and Fe3O4 nanoparticle binary hollow and bowl-like superstructures as recyclable catalysts for industrial wastewater treatment.

    PubMed

    Zhang, Xue; Lin, Min; Lin, Xiaoying; Zhang, Chunting; Wei, Haotong; Zhang, Hao; Yang, Bai

    2014-01-01

    Metal and metal-oxide nanoparticles (NPs) are promising catalysts for dye degradation in wastewater treatment despite the challenges of NP recovery and recycling. In this study, water-dispersible NP superstructures with spherical morphology were constructed from hydrophobic Pd and Fe3O4 NPs by virtue of the oil droplets in an oil-in-water microemulsion as templates. Control of the evaporation rate of organic solvents in the oil droplets produces solid, hollow, and bowl-like superstructures. The component Fe3O4 and in particular Pd NPs can catalyze H2O2 degradation to create hydroxyl radicals and therewith degrade various dyes, and the magnetic Fe3O4 NPs also permit recycling of the superstructures with a magnet. Because the hollow and bowl-like superstructures increase the contact area of the NPs with their surroundings in comparison to solid superstructures, the catalytic activity is greatly enhanced. To improve the structural stability, the superstructures were further enveloped with a thin polypyrrole (PPy) shell, which does not weaken the catalytic activity. Because the current method is facile and feasible to create recyclable catalysts, it will promote the practicability of NP catalysts in treating industrial polluted water. PMID:24266702

  3. Highly catalytic hollow palladium nanoparticles derived from silver@silver-palladium core-shell nanostructures for the oxidation of formic acid

    NASA Astrophysics Data System (ADS)

    Chen, Dong; Cui, Penglei; He, Hongyan; Liu, Hui; Yang, Jun

    2014-12-01

    Hollow Palladium (hPd) nanoparticles (NPs) are prepared via a simple and mild successive method. Firstly, core-shell NPs with silver (Ag) cores and silver-palladium (Ag-Pd) alloy shells are synthesized in aqueous phase by galvanic replacement reaction (GRR) between Ag NPs and Pd2+ ion precursors. Saturated aqueous sodium chloride (NaCl) solution was then employed to remove the Ag component from the core and shell regions of core-shell Ag@Ag-Pd NPs, resulting in the formation of hPd NPs with shrunk sizes in comparison with their core-shell parents. Specifically, the hPd NPs exhibit superior catalytic activity and durability for catalyzing the oxidation of formic acid, compared with the Pd NPs reduced by NaBH4 in aqueous solution and commercial Pd/C catalyst from Johnson Matthey, mainly due to the large electrochemically active surface areas of the hollow particles. In addition, The Ag component in core-shell Ag@Ag-Pd NPs has an unfavorable influence on catalytic activity of NPs for formic acid oxidation. However, the durability could be improved due to the electron donating effect from Ag to Pd atoms in the core-shell NPs.

  4. Na-ion Storage Performances of FeSex and Fe2O3 Hollow Nanoparticles-Decorated Reduced Graphene Oxide Balls prepared by Nanoscale Kirkendall Diffusion Process

    PubMed Central

    Park, Gi Dae; Cho, Jung Sang; Lee, Jung-Kul; Kang, Yun Chan

    2016-01-01

    Uniquely structured FeSex-reduced graphene oxide (rGO) composite powders, in which hollow FeSex nanoparticles are uniformly distributed throughout the rGO matrix, were prepared by spray pyrolysis applying the nanoscale Kirkendall diffusion process. Iron oxide-rGO composite powders were transformed into FeSex-rGO composite powders by a two-step post-treatment process. Metallic Fe nanocrystals formed during the first-step post-treatment process were transformed into hollow FeSex nanoparticles during the selenization process. The FeSex-rGO composite powders had mixed crystal structures of FeSe and FeSe2 phases. A rGO content of 33% was estimated from the TG analysis of the FeSex-rGO composite powders. The FeSex-rGO composite powders had superior sodium-ion storage properties compared to those of the Fe2O3-rGO composite powders with similar morphological characteristics. The discharge capacities of the FeSex- and Fe2O3-rGO composite powders for the 200th cycle at a constant current density of 0.3 A g−1 were 434 and 174 mA h g−1, respectively. The FeSex-rGO composite powders had a high discharge capacity of 311 mA h g−1 for the 1000th cycle at a high current density of 1 A g−1. PMID:26928312

  5. SERS of Individual Nanoparticles on a Mirror: Size Does Matter, but so Does Shape

    PubMed Central

    2016-01-01

    Coupling noble metal nanoparticles by a 1 nm gap to an underlying gold mirror confines light to extremely small volumes, useful for sensing on the nanoscale. Individually measuring 10 000 of such gold nanoparticles of increasing size dramatically shows the different scaling of their optical scattering (far-field) and surface-enhanced Raman emission (SERS, near-field). Linear red-shifts of the coupled plasmon modes are seen with increasing size, matching theory. The total SERS from the few hundred molecules under each nanoparticle dramatically increases with increasing size. This scaling shows that maximum SERS emission is always produced from the largest nanoparticles, irrespective of tuning to any plasmonic resonances. Changes of particle facet with nanoparticle size result in vastly weaker scaling of the near-field SERS, without much modifying the far-field, and allows simple approaches for optimizing practical sensing. PMID:27223478

  6. DNA-mediated construction of hollow upconversion nanoparticles for protein harvesting and near-infrared light triggered release.

    PubMed

    Zhou, Li; Chen, Zhaowei; Dong, Kai; Yin, Meili; Ren, Jinsong; Qu, Xiaogang

    2014-04-16

    A simple DNA-mediated solvothermal method has been developed for the construction of well-defined hollow UNPs that can be used for a new paradigm to realize NIR light-controlled non-invasive protein release. In vitro studies show that the UNPs are capable of the transportation of enzyme into living cells. Intracellular NIR triggers the release of enzymes with high spatial and temporal precision and the released enzyme also retains its biological activity.

  7. Core-shell-corona polymeric micelles as a versatile template for synthesis of inorganic hollow nanospheres.

    PubMed

    Sasidharan, Manickam; Nakashima, Kenichi

    2014-01-21

    Hollow, inorganic nanoscale capsules have many applications, from the delivery of encapsulated products for cosmetic and medicinal purposes to use as lightweight composite materials. Early methods for producing inorganic hollow nanospheres using hard templates suffered from low product yield and shell weakness upon template removal. In the past decade, researchers have turned to amphiphilic copolymers to synthesize hollow nanostructures and ordered mesoporous materials. Amphiphilic molecules self-assemble into well-defined nanostructures including spherical micelles. Micelles formed from simple, two-component AB diblock and ABA triblock copolymers, however, have been difficult to work with to construct inorganic hollow nanoparticles, because the corona of the micelle, which serves as the template for the shell, becomes unstable as it absorbs inorganic shell precursors, causing aggregates to form. Newly developed, three-component ABC triblock copolymers may solve this problem. They provide nanoassemblies with more diverse morphological and functional features than AB diblock and ABA triblock copolymers. Micelles formed from ABC triblock copolymers in selective solvents that dissolve only one or two of the blocks provide templates for these improved nanoassemblies. By manipulating individual polymer blocks, one can "encode" additional features at the molecular level. For instance, modifying the functional groups or substitution patterns of the blocks allows better morphological and size control. Insights into polymer self-assembly gained over years of work in our group have set the stage to systematically engineer inorganic spherical hollow nanoparticles using ABC triblock copolymers. In this Account, we report our recent progress in producing diverse, inorganic hollow spherical nanospheres from asymmetric triblock copolymeric micelles with core-shell-corona architecture as templates. We discuss three classes of polymeric micelles-with neutral, cationic, and anionic

  8. ZnO-based hollow nanoparticles by selective etching: elimination and reconstruction of metal-semiconductor interface, improvement of blue emission and photocatalysis.

    PubMed

    Zeng, Haibo; Cai, Weiping; Liu, Peisheng; Xu, Xiaoxia; Zhou, Huijuan; Klingshirn, Claus; Kalt, Heinz

    2008-08-01

    A weak acid selective etching strategy was put forward to fabricate oxide-based hollow nanoparticles (HNPs) using core/shell nanostructures of active metal/oxide nanoparticles as sacrificial templates. ZnO-based HNPs, including pure ZnO, Au/ZnO, Pt/ZnO, and Au/Pt/ZnO HNPs with diameter below 50 nm and shell thickness below 6 nm has been first achieved at low temperature. The diameter, thickness, and even sizes of ZnO and noble metal ultrafine crystals of HNPs can be well adjusted by the etching process. Synchronous with the formation of HNPs, the internal metal-semiconductor interfaces can be controllably eliminated (Zn-ZnO) and reconstructed (noble metal-ZnO). Excitingly, such microstructure manipulation has endued them with giant improvements in related performances, including the very strong blue luminescence with enhancement over 3 orders of magnitude for the pure ZnO HNPs and the greatly improved photocatalytic activity for the noble metal/ZnO HNPs. These give them strong potentials in relevant applications, such as blue light emitting devices, environment remediation, drug delivery and release, energy storage and conversion, and sensors. The designed fabrication procedure is simple, feasible, and universal for a series of oxide and noble metal/oxide HNPs with controlled microstructure and improved performances.

  9. Computer simulation of MHD blood conveying gold nanoparticles as a third grade non-Newtonian nanofluid in a hollow porous vessel.

    PubMed

    Hatami, M; Hatami, J; Ganji, D D

    2014-02-01

    In this paper, heat transfer and flow analysis for a non-Newtonian third grade nanofluid flow in porous medium of a hollow vessel in presence of magnetic field are simulated analytically and numerically. Blood is considered as the base third grade non-Newtonian fluid and gold (Au) as nanoparticles are added to it. The viscosity of nanofluid is considered a function of temperature as Vogel's model. Least Square Method (LSM), Galerkin method (GM) and fourth-order Runge-Kutta numerical method (NUM) are used to solve the present problem. The influences of the some physical parameters such as Brownian motion and thermophoresis parameters on non-dimensional velocity and temperature profiles are considered. The results show that increasing the thermophoresis parameter (N(t)) caused an increase in temperature values in whole domain and an increase in nanoparticles concentration just near the inner wall of vessel. Furthermore by increasing the MHD parameter, velocity profiles decreased due to magnetic field effect. PMID:24286727

  10. Multi-Order Investigation of the Nonlinear Susceptibility Tensors of Individual Nanoparticles

    PubMed Central

    Schmidt, Cédric; Riporto, Jérémy; Uldry, Aline; Rogov, Andrii; Mugnier, Yannick; Dantec, Ronan Le; Wolf, Jean-Pierre; Bonacina, Luigi

    2016-01-01

    We use Hyper Rayleigh Scattering and polarization resolved multiphoton microscopy to investigate simultaneously the second and third-order nonlinear response of Potassium Niobate and Bismuth Ferrite harmonic nanoparticles. We first derive the second-to-third harmonic intensity ratio for colloidal ensembles and estimate the average third-order efficiency of these two materials. Successively, we explore the orientation dependent tensorial response of individual nanoparticles fixed on a substrate. The multi-order polarization resolved emission curves are globally fitted with an analytical model to retrieve individual elements of susceptibility tensors. PMID:27140074

  11. Multi-Order Investigation of the Nonlinear Susceptibility Tensors of Individual Nanoparticles

    NASA Astrophysics Data System (ADS)

    Schmidt, Cédric; Riporto, Jérémy; Uldry, Aline; Rogov, Andrii; Mugnier, Yannick; Dantec, Ronan Le; Wolf, Jean-Pierre; Bonacina, Luigi

    2016-05-01

    We use Hyper Rayleigh Scattering and polarization resolved multiphoton microscopy to investigate simultaneously the second and third-order nonlinear response of Potassium Niobate and Bismuth Ferrite harmonic nanoparticles. We first derive the second-to-third harmonic intensity ratio for colloidal ensembles and estimate the average third-order efficiency of these two materials. Successively, we explore the orientation dependent tensorial response of individual nanoparticles fixed on a substrate. The multi-order polarization resolved emission curves are globally fitted with an analytical model to retrieve individual elements of susceptibility tensors.

  12. Hollow Retroreflectors

    NASA Technical Reports Server (NTRS)

    1993-01-01

    A hollow retroreflector is a mirror-like instrument that reflects light and other radiations back to the source. After developing a hollow retroreflector for NASA's Apollo-Soyuz mission, PLX, Inc. continued to expand the technology and develop a variety of retroreflector systems. The Lateral Transfer Hollow Retroreflector maintains precise separation, at any wavelength, of incoming and existing beams regardless of their orientation. It can be used as an instrument or as a component of an optical system. In the laboratory, it offers a new efficient means of beam positioning. In other applications, it connects laser resonators, aligns telescope mirrors and is useful in general boresighting and alignment.

  13. A novel platform for high sensitivity determination of PbP2a based on gold nanoparticles composited graphitized mesoporous carbon and doxorubicin loaded hollow gold nanospheres.

    PubMed

    Yang, Juan; Shen, Huawei; Zhang, Xing; Tao, Yiyi; Xiang, Hua; Xie, Guoming

    2016-03-15

    Gold nanoparticles composite graphitized mesoporous carbon nanoparticles (GMCs@AuNPs) biocomposite with the signal amplification capability was successfully synthesized for use in an immunoassay for penicillin binding protein 2 a (PbP2a). The polyamidoamine (PAMAM) dendrimers were first electrodeposited onto the Au electrode can greatly increase the amount of the captured antibodies. Protein A was used to properly orientate immobilized antibody against PbP2a, which strongly improved specificity of the antigen-antibody binding. Hollow gold nanospheres (HGNPs) as effective nanocarriers have been synthesized by sacrificial galvanic replacement of cobalt nanoparticles capable of encapsulating doxorubicin (Dox). The obtained HGNPs@Dox bionanocomposite was used for further loading of detection antibody (Ab2) to form the HGNPs@Dox@Ab2 bioconjugate. Then, the differential pulse voltammetric signals related to the concentration of PbP2a for Dox could be detected, and the immunosensor exhibited a detection limit as low as 0.65 pg mL(-1) (at an S/N ratio of 3). The proposed method with an excellent differentiation ability showed high sensitivity and specificity. The morphologies and electrochemistry properties of the composites were investigated by scanning electron microscopy, electrochemical characterization, UV-visible absorption spectroscopy, fluorescence spectrophotometer and Malvern laser particle size analyzer, respectively. In addition, the basic approach described here would be applicable towards developing biodetection assays against other important targets. Moreover, the bioconjugate of HGNPs@Dox is also a promising pattern to delivery Dox in vivo for anticancer therapy. PMID:26569442

  14. Hollow Microporous Organic Capsules

    PubMed Central

    Li, Buyi; Yang, Xinjia; Xia, Lingling; Majeed, Muhammad Irfan; Tan, Bien

    2013-01-01

    Fabrication of hollow microporous organic capsules (HMOCs) could be very useful because of their hollow and porous morphology, which combines the advantages of both microporous organic polymers and non-porous nanocapsules. They can be used as storage materials or reaction chambers while supplying the necessary path for the design of controlled uptake/release systems. Herein, the synthesis of HMOCs with high surface area through facile emulsion polymerization and hypercrosslinking reactions, is described. Due to their tailored porous structure, these capsules possessed high drug loading efficiency, zero-order drug release kinetics and are also demonstrated to be used as nanoscale reactors for the prepareation of nanoparticles (NPs) without any external stabilizer. Moreover, owing to their intrinsic biocompatibility and fluorescence, these capsules exhibit promising prospect for biomedical applications. PMID:23820511

  15. Sequential enrichment with titania-coated magnetic mesoporous hollow silica microspheres and zirconium arsenate-modified magnetic nanoparticles for the study of phosphoproteome of HL60 cells.

    PubMed

    Yu, Qiong-Wei; Li, Xiao-Shui; Xiao, Yongsheng; Guo, Lei; Zhang, Fan; Cai, Qian; Feng, Yu-Qi; Yuan, Bi-Feng; Wang, Yinsheng

    2014-10-24

    As one of the most important types of post-translational modifications, reversible phosphorylation of proteins plays crucial roles in a large number of biological processes. However, owing to the relatively low abundance and dynamic nature of phosphorylation and the presence of the unphosphorylated peptides in large excess, phosphopeptide enrichment is indispensable in large-scale phosphoproteomic analysis. Metal oxides including titanium dioxide have become prominent affinity materials to enrich phosphopeptides prior to their analysis using liquid chromatography-mass spectrometry (LC-MS). In the current study, we established a novel strategy, which encompassed strong cation exchange chromatography, sequential enrichment of phosphopeptides using titania-coated magnetic mesoporous hollow silica microspheres (TiO2/MHMSS) and zirconium arsenate-modified magnetic nanoparticles (ZrAs-Fe3O4@SiO2), and LC-MS/MS analysis, for the proteome-wide identification of phosphosites of proteins in HL60 cells. In total, we were able to identify 11,579 unique phosphorylation sites in 3432 unique proteins. Additionally, our results suggested that TiO2/MHMSS and ZrAs-Fe3O4@SiO2 are complementary in phosphopeptide enrichment, where the two types of materials displayed preferential binding of peptides carrying multiple and single phosphorylation sites, respectively.

  16. Sequential enrichment with titania-coated magnetic mesoporous hollow silica microspheres and zirconium arsenate-modified magnetic nanoparticles for the study of phosphoproteome of HL60 cells.

    PubMed

    Yu, Qiong-Wei; Li, Xiao-Shui; Xiao, Yongsheng; Guo, Lei; Zhang, Fan; Cai, Qian; Feng, Yu-Qi; Yuan, Bi-Feng; Wang, Yinsheng

    2014-10-24

    As one of the most important types of post-translational modifications, reversible phosphorylation of proteins plays crucial roles in a large number of biological processes. However, owing to the relatively low abundance and dynamic nature of phosphorylation and the presence of the unphosphorylated peptides in large excess, phosphopeptide enrichment is indispensable in large-scale phosphoproteomic analysis. Metal oxides including titanium dioxide have become prominent affinity materials to enrich phosphopeptides prior to their analysis using liquid chromatography-mass spectrometry (LC-MS). In the current study, we established a novel strategy, which encompassed strong cation exchange chromatography, sequential enrichment of phosphopeptides using titania-coated magnetic mesoporous hollow silica microspheres (TiO2/MHMSS) and zirconium arsenate-modified magnetic nanoparticles (ZrAs-Fe3O4@SiO2), and LC-MS/MS analysis, for the proteome-wide identification of phosphosites of proteins in HL60 cells. In total, we were able to identify 11,579 unique phosphorylation sites in 3432 unique proteins. Additionally, our results suggested that TiO2/MHMSS and ZrAs-Fe3O4@SiO2 are complementary in phosphopeptide enrichment, where the two types of materials displayed preferential binding of peptides carrying multiple and single phosphorylation sites, respectively. PMID:25262027

  17. Performance of an optimized Zr-based nanoparticle-embedded PSF blend hollow fiber membrane in treatment of fluoride contaminated water.

    PubMed

    He, Jinsong; Siah, Tiong-Shie; Paul Chen, J

    2014-06-01

    Consumption of water that has excessive fluoride can cause adverse health impacts on human beings. A Zr-based nanoparticle-embedded PSF blend hollow fiber membrane was successfully prepared and optimized for removal of fluoride from the aqueous solution. Both static and dynamic adsorption of fluoride on the membrane was investigated. It was showed that the membrane could effectively remove fluoride within a wide pH ranging from 3 to 10. At neutral pH, the adsorption equilibrium was reached within 24 h. The maximum adsorption capacity of the optimized membrane was 60.65 mg/g, much higher than many commercial adsorbents. The presence of NO3(-), SiO3(2-) or HA has insignificant effects on the fluoride removal. However, the removal was retarded as the concentration of HCO3(-) or PO4(3-) was increased. Furthermore, the membrane could remove fluoride efficiently through the continuous filtration, even in presence of natural organic matters. The spent membrane could be regenerated and then reused for the removal of fluoride with great efficiency. The adsorption history could be well described by an intraparticle diffusion model. The XPS analysis showed that the adsorption of fluoride was mainly associated with the ion-exchange between SO4(2-) and F(-) ions. Finally, the toxicity analysis revealed that the treated water was safe for human consumption. PMID:24657326

  18. Synthesis of an ultradense forest of vertically aligned triple-walled carbon nanotubes of uniform diameter and length using hollow catalytic nanoparticles.

    PubMed

    Baliyan, Ankur; Nakajima, Yoshikata; Fukuda, Takahiro; Uchida, Takashi; Hanajiri, Tatsuro; Maekawa, Toru

    2014-01-22

    It still remains a crucial challenge to actively control carbon nanotube (CNT) structure such as the alignment, area density, diameter, length, chirality, and number of walls. Here, we synthesize an ultradense forest of CNTs of a uniform internal diameter by the plasma-enhanced chemical vapor deposition (PECVD) method using hollow nanoparticles (HNPs) modified with ligand as a catalyst. The diameters of the HNPs and internal cavities in the HNPs are uniform. A monolayer of densely packed HNPs is self-assembled on a silicon substrate by spin coating. HNPs shrink via the collapse of the internal cavities and phase transition from iron oxide to metallic iron in hydrogen plasma during the PECVD process. Agglomeration of catalytic NPs is avoided on account of the shrinkage of the NPs and ligand attached to the NPs. Diffusion of NPs into the substrate, which would inactivate the growth of CNTs, is also avoided on account of the ligand. As a result, an ultradense forest of triple-walled CNTs of a uniform internal diameter is successfully synthesized. The area density of the grown CNTs is as high as 0.6 × 10(12) cm(-2). Finally, the activity of the catalytic NPs and the NP/carbon interactions during the growth process of CNTs are investigated and discussed. We believe that the present approach may make a great contribution to the development of an innovative synthetic method for CNTs with selective properties. PMID:24369068

  19. Frog Hollow.

    ERIC Educational Resources Information Center

    McCardell, Bonnie

    1979-01-01

    The Vermont State Craft Center, Frog Hollow, in Middlebury, Vermont, provides studio space and instruction to students from two elementary schools, a day-care center, the county school for the mentally retarded, and an area kindergarten. Described are the programs offered to each of these groups of students. (Author/KC)

  20. Observation of intrinsic size effects in the optical response of individual gold nanoparticles.

    PubMed

    Berciaud, Stéphane; Cognet, Laurent; Tamarat, Philippe; Lounis, Brahim

    2005-03-01

    The photothermal heterodyne imaging method is used to study for the first time the absorption spectra of individual gold nanoparticles with diameters down to 5 nm. Intrinsic size effects that result in a broadening of the surface plasmon resonance are unambiguously observed. Dispersions in the peak energies and homogeneous widths of the single-particle resonances are revealed. The experimental results are analyzed within the frame of Mie theory. PMID:15755105

  1. Overcoming acquired drug resistance in colorectal cancer cells by targeted delivery of 5-FU with EGF grafted hollow mesoporous silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, Lijue; She, Xiaodong; Wang, Tao; He, Li; Shigdar, Sarah; Duan, Wei; Kong, Lingxue

    2015-08-01

    Acquired drug resistance (ADR) can be developed in colorectal cancer cells after 5-fluorouracil (5-FU) treatment and diminish the effectiveness of chemotherapy. In this work, acquired 5-FU resistance in the colorectal cancer cell line SW480 was obtained with the up-regulation of dihydropyrimidine dehydrogenase (DPYD) gene expression which can convert 5-FU to its inactive metabolite. To overcome ADR in colorectal cancer, hollow mesoporous silica nanoparticles (HMSNs) grafted with epidermal growth factor (EGF) were used as nanocarriers to deliver 5-FU to colorectal cancer cells with acquired drug resistance. The effect and mechanism of 5-FU loaded EGF grafted HMSNs (EGF-HMSNs-5-FU) in overcoming acquired drug resistance in SW480/ADR cells were studied. The EGF-HMSNs were demonstrated to be specifically internalized in EGFR overexpressed SW480/ADR cells via a receptor-mediated endocytosis and can escape from endo-lysosomes. The EGF-HMSNs-5-FU exhibited much higher cytotoxicity on SW480/ADR cells than HMSNs-5-FU and free 5-FU while the plain HMSNs did not show significant cytotoxicity. The mechanism of EGF-HMSNs-5-FU in overcoming drug resistance in SW480/ADR cells could be attributed to the specific internalization of EGF-HMSNs-5-FU in EGFR overexpressed cells which can lead to high intracellular drug accumulation and cause cell death through S phase arrest.Acquired drug resistance (ADR) can be developed in colorectal cancer cells after 5-fluorouracil (5-FU) treatment and diminish the effectiveness of chemotherapy. In this work, acquired 5-FU resistance in the colorectal cancer cell line SW480 was obtained with the up-regulation of dihydropyrimidine dehydrogenase (DPYD) gene expression which can convert 5-FU to its inactive metabolite. To overcome ADR in colorectal cancer, hollow mesoporous silica nanoparticles (HMSNs) grafted with epidermal growth factor (EGF) were used as nanocarriers to deliver 5-FU to colorectal cancer cells with acquired drug resistance. The

  2. Pd Nanoparticles Decorated N-Doped Graphene Quantum Dots@N-Doped Carbon Hollow Nanospheres with High Electrochemical Sensing Performance in Cancer Detection.

    PubMed

    Xi, Jiangbo; Xie, Chuyi; Zhang, Yan; Wang, Lu; Xiao, Jian; Duan, Xianming; Ren, Jinghua; Xiao, Fei; Wang, Shuai

    2016-08-31

    The development of carbon based hollow-structured nanospheres (HNSs) materials has stimulated growing interest due to their controllable structure, high specific surface area, large void space, enhanced mass transport, and good biocompatibility. The incorporation of functional nanomaterials into their core and/or shell opens new horizons in designing functionalized HNSs for a wider spectrum of promising applications. In this work, we report a new type of functionalized HNSs based on Pd nanoparticles (NPs) decorated double shell structured N-doped graphene quantum dots (NGQDs)@N-doped carbon (NC) HNSs, with ultrafine Pd NPs and "nanozyme" NGQDs as dual signal-amplifying nanoprobes, and explore their promising application as a highly efficient electrocatalyst in electrochemical sensing of a newly emerging biomarker, i.e., hydrogen peroxide (H2O2), for cancer detection. Due to the synergistic effect of the robust and conductive HNS supports and catalytically active Pd NPs and NGQD in facilitating electron transfer, the NGQD@NC@Pd HNS hybrid material exhibits high electrocatalytic activity toward the direct reduction of H2O2 and can promote the electrochemical reduction reaction of H2O2 at a favorable potential of 0 V, which effectively restrains the redox of most electroactive species in physiological samples and eliminates interference signals. The resultant electrochemical H2O2 biosensor based hybrid HNSs materials demonstrates attractive performance, including low detection limit down to nanomole level, short response time within 2 s, as well as high sensitivity, reproducibility, selectivity, and stability, and have been used in real-time tracking of trace amounts of H2O2 secreted from different living cancer cells in a normal state and treated with chemotherapy and radiotherapy.

  3. Two-phase equilibrium states in individual Cu–Ni nanoparticles: size, depletion and hysteresis effects

    PubMed Central

    2015-01-01

    Summary In isolated bimetallic nanoscale systems the limit amount of matter and surface-induced size effects can change the thermodynamics of first-order phase transformation. In this paper we present theoretical modification of Gibbs free energy concept describing first-order phase transformation of binary alloyed nanoparticles taking into account size effects as well as depletion and hysteresis effects. In such a way the hysteresis in a form of nonsymmetry for forth and back transforming paths takes place; compositional splitting and the loops-like splitted path on the size dependent temperature–composition phase diagram occur. Our calculations for individual Cu–Ni nanoparticle show that one must differentiate the solubility curves and the equilibrium loops (discussed here in term of solidification and melting loops). For the first time we have calculated and present here on the temperature–composition phase diagram the nanomelting loop at the size of 80 nm and the nanosolidification loop at the size of 25 nm for an individual Cu–Ni nanoparticle. So we observe the difference between the size-dependent phase diagram and solubility diagram, between two-phase equilibrium curves and solubility curves; also intersection of nanoliquidus and nanosolidus is available. These findings lead to the necessity to reconsider such basic concepts in materials science as phase diagram and solubility diagram. PMID:26425433

  4. Designing Hollow Nano Gold Golf Balls

    PubMed Central

    2015-01-01

    Hollow/porous nanoparticles, including nanocarriers, nanoshells, and mesoporous materials have applications in catalysis, photonics, biosensing, and delivery of theranostic agents. Using a hierarchical template synthesis scheme, we have synthesized a nanocarrier mimicking a golf ball, consisting of (i) solid silica core with a pitted gold surface and (ii) a hollow/porous gold shell without silica. The template consisted of 100 nm polystyrene beads attached to a larger silica core. Selective gold plating of the core followed by removal of the polystyrene beads produced a golf ball-like nanostructure with 100 nm pits. Dissolution of the silica core produced a hollow/porous golf ball-like nanostructure. PMID:24937196

  5. Hollow Electrode Discharge Triodes

    NASA Astrophysics Data System (ADS)

    Schoenbach, K. H.; Peterkin, F. E.; Tessnow, T.

    1996-10-01

    The current through a direct current micro-hollow electrode (electrode hole diameter: 0.7 mm) discharge in argon was shown to be controllable by means of a third, external electrode placed close to the cathode opening. By increasing the potential of the positively biased control electrode from zero to 30 V the discharge current could be linearly reduced from 5 μA to 0.75 μA, at a discharge voltage of 300 V. The current-voltage characteristic of the micro-hollow electrode discharge was found to have a positive slope, allowing parallel discharge operation without ballast. By drilling holes through a metal-plated, dielectric film, an array of hollow electrode discharges could be generated. It was shown that each discharge responds individually to variations in the potential of the corresponding external control electrode. The simplicity of the electrode configuration and the possibility of linear, electrical control of the individual discharge currents offers the possibility to use these triode arrays in addressable flat panel displays (patent pending).

  6. Synthesis of 1D Fe₃O₄/P(MBAAm-co-MAA) nanochains as stabilizers for Ag nanoparticles and templates for hollow mesoporous structure, and their applications in catalytic reaction and drug delivery.

    PubMed

    Zhang, Wei; Si, Xiaowei; Liu, Bin; Bian, Guomin; Qi, Yonglin; Yang, Xinlin; Li, Chenxi

    2015-10-15

    One-dimensional (1D) magnetic Fe3O4/P(MBAAm-co-MAA) nanochains were prepared by distillation-precipitation polymerization of MBAAm and MAA in the presence of Fe3O4 nanoparticles as building blocks under a magnetic heating stirrer, which played two critical roles: serving as magnetic field to induce the self-assembly of Fe3O4 nanoparticles into 1D nanochains and providing thermal energy to induce the polymerization of MAA and MBAAm on the surface of the Fe3O4 nanoparticles. The thickness of the P(MBAAm-co-MAA) layer can be easily tuned by adjusting the successive polymerization steps. The polymer layer that contained carboxyl groups was used as stabilizers for loading Ag nanoparticles and the reaction locus for deposition of outer silica layer via a sol-gel method in presence of C18TMS as the pore directing agent for tri-layer nanochains. The corresponding hollow mesoporous silica nanochains with movable maghemite cores (γ-Fe2O3@mSiO2) were produced after removal of the polymer mid-layer and the alkyl groups of the pore directing agent via calcination of the tri-layer nanochains at high temperature. The Fe3O4/P(MBAAm-co-MAA)/Ag nanochains exhibited a highly catalytic efficiency and well reusable property toward the reduction of nitrophenol. Furthermore, the γ-Fe2O3@mSiO2 nanochains possessed hollow mesoporous structure and high specific surface area (197.2 m(2) g(-1)) were used as a drug carrier, which displayed a controlled release property.

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

    PubMed

    Chen, Guozhu; Rosei, Federico; Ma, Dongling

    2015-03-19

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

  8. Crystallography Without Crystals: Determining the Structure of Individual Biological Molecules and Nanoparticles

    ScienceCinema

    Ourmazd, Abbas [University of Wisconsin, Milwaukee, Wisconsin, USA

    2016-07-12

    Ever shattered a valuable vase into 10 to the 6th power pieces and tried to reassemble it under a light providing a mean photon count of 10 minus 2 per detector pixel with shot noise? If you can do that, you can do single-molecule crystallography. This talk will outline how this can be done in principle. In more technical terms, the talk will describe how the combination of scattering physics and Bayesian algorithms can be used to reconstruct the 3-D diffracted intensity distribution from a collection of individual 2-D diffiraction patterns down to a mean photon count of 10 minus 2 per pixel, the signal level anticipated from the Linac Coherent Light Source, and hence determine the structure of individual macromolecules and nanoparticles.

  9. Immunisation of Sheep with Bovine Viral Diarrhoea Virus, E2 Protein Using a Freeze-Dried Hollow Silica Mesoporous Nanoparticle Formulation.

    PubMed

    Mahony, Donna; Mody, Karishma T; Cavallaro, Antonino S; Hu, Qiuhong; Mahony, Timothy J; Qiao, Shizhang; Mitter, Neena

    2015-01-01

    Bovine viral diarrhoea virus 1 (BVDV-1) is arguably the most important viral disease of cattle. It is associated with reproductive, respiratory and chronic diseases in cattle across the world. In this study we have investigated the capacity of the major immunological determinant of BVDV-1, the E2 protein combined with hollow type mesoporous silica nanoparticles with surface amino functionalisation (HMSA), to stimulate immune responses in sheep. The current work also investigated the immunogenicity of the E2 nanoformulation before and after freeze-drying processes. The optimal excipient formulation for freeze-drying of the E2 nanoformulation was determined to be 5% trehalose and 1% glycine. This excipient formulation preserved both the E2 protein integrity and HMSA particle structure. Sheep were immunised three times at three week intervals by subcutaneous injection with 500 μg E2 adsorbed to 6.2 mg HMSA as either a non-freeze-dried or freeze-dried nanoformulation. The capacity of both nanovaccine formulations to generate humoral (antibody) and cell-mediated responses in sheep were compared to the responses in sheep immunisation with Opti-E2 (500 μg) together with the conventional adjuvant Quil-A (1 mg), a saponin from the Molina tree (Quillaja saponira). The level of the antibody responses detected to both the non-freeze-dried and freeze-dried Opti-E2/HMSA nanoformulations were similar to those obtained for Opti-E2 plus Quil-A, demonstrating the E2 nanoformulations were immunogenic in a large animal, and freeze-drying did not affect the immunogenicity of the E2 antigen. Importantly, it was demonstrated that the long term cell-mediated immune responses were detectable up to four months after immunisation. The cell-mediated immune responses were consistently high in all sheep immunised with the freeze-dried Opti-E2/HMSA nanovaccine formulation (>2,290 SFU/million cells) compared to the non-freeze-dried nanovaccine formulation (213-500 SFU/million cells). This study

  10. Immunisation of Sheep with Bovine Viral Diarrhoea Virus, E2 Protein Using a Freeze-Dried Hollow Silica Mesoporous Nanoparticle Formulation

    PubMed Central

    Mahony, Donna; Mody, Karishma T.; Cavallaro, Antonino S.; Hu, Qiuhong; Mahony, Timothy J.; Qiao, Shizhang; Mitter, Neena

    2015-01-01

    Bovine viral diarrhoea virus 1 (BVDV-1) is arguably the most important viral disease of cattle. It is associated with reproductive, respiratory and chronic diseases in cattle across the world. In this study we have investigated the capacity of the major immunological determinant of BVDV-1, the E2 protein combined with hollow type mesoporous silica nanoparticles with surface amino functionalisation (HMSA), to stimulate immune responses in sheep. The current work also investigated the immunogenicity of the E2 nanoformulation before and after freeze-drying processes. The optimal excipient formulation for freeze-drying of the E2 nanoformulation was determined to be 5% trehalose and 1% glycine. This excipient formulation preserved both the E2 protein integrity and HMSA particle structure. Sheep were immunised three times at three week intervals by subcutaneous injection with 500 μg E2 adsorbed to 6.2 mg HMSA as either a non-freeze-dried or freeze-dried nanoformulation. The capacity of both nanovaccine formulations to generate humoral (antibody) and cell-mediated responses in sheep were compared to the responses in sheep immunisation with Opti-E2 (500 μg) together with the conventional adjuvant Quil-A (1 mg), a saponin from the Molina tree (Quillaja saponira). The level of the antibody responses detected to both the non-freeze-dried and freeze-dried Opti-E2/HMSA nanoformulations were similar to those obtained for Opti-E2 plus Quil-A, demonstrating the E2 nanoformulations were immunogenic in a large animal, and freeze-drying did not affect the immunogenicity of the E2 antigen. Importantly, it was demonstrated that the long term cell-mediated immune responses were detectable up to four months after immunisation. The cell-mediated immune responses were consistently high in all sheep immunised with the freeze-dried Opti-E2/HMSA nanovaccine formulation (>2,290 SFU/million cells) compared to the non-freeze-dried nanovaccine formulation (213–500 SFU/million cells). This

  11. Immunisation of Sheep with Bovine Viral Diarrhoea Virus, E2 Protein Using a Freeze-Dried Hollow Silica Mesoporous Nanoparticle Formulation.

    PubMed

    Mahony, Donna; Mody, Karishma T; Cavallaro, Antonino S; Hu, Qiuhong; Mahony, Timothy J; Qiao, Shizhang; Mitter, Neena

    2015-01-01

    Bovine viral diarrhoea virus 1 (BVDV-1) is arguably the most important viral disease of cattle. It is associated with reproductive, respiratory and chronic diseases in cattle across the world. In this study we have investigated the capacity of the major immunological determinant of BVDV-1, the E2 protein combined with hollow type mesoporous silica nanoparticles with surface amino functionalisation (HMSA), to stimulate immune responses in sheep. The current work also investigated the immunogenicity of the E2 nanoformulation before and after freeze-drying processes. The optimal excipient formulation for freeze-drying of the E2 nanoformulation was determined to be 5% trehalose and 1% glycine. This excipient formulation preserved both the E2 protein integrity and HMSA particle structure. Sheep were immunised three times at three week intervals by subcutaneous injection with 500 μg E2 adsorbed to 6.2 mg HMSA as either a non-freeze-dried or freeze-dried nanoformulation. The capacity of both nanovaccine formulations to generate humoral (antibody) and cell-mediated responses in sheep were compared to the responses in sheep immunisation with Opti-E2 (500 μg) together with the conventional adjuvant Quil-A (1 mg), a saponin from the Molina tree (Quillaja saponira). The level of the antibody responses detected to both the non-freeze-dried and freeze-dried Opti-E2/HMSA nanoformulations were similar to those obtained for Opti-E2 plus Quil-A, demonstrating the E2 nanoformulations were immunogenic in a large animal, and freeze-drying did not affect the immunogenicity of the E2 antigen. Importantly, it was demonstrated that the long term cell-mediated immune responses were detectable up to four months after immunisation. The cell-mediated immune responses were consistently high in all sheep immunised with the freeze-dried Opti-E2/HMSA nanovaccine formulation (>2,290 SFU/million cells) compared to the non-freeze-dried nanovaccine formulation (213-500 SFU/million cells). This study

  12. Direct imaging of the magnetic polarity and reversal mechanism in individual Fe(3-x)O4 nanoparticles.

    PubMed

    Moya, Carlos; Iglesias-Freire, Óscar; Pérez, Nicolás; Batlle, Xavier; Labarta, Amilcar; Asenjo, Agustina

    2015-05-01

    This work reports on the experimental characterization of the magnetic domain configurations in cubic, isolated Fe3-xO4 nanoparticles with a lateral size of 25-30 nm. The magnetic polarity at remanence of single domain ferrimagnetic Fe3-xO4 nanoparticles deposited onto a carbon-silicon wafer is observed by magnetic force microscopy. The orientations of these domains provide a direct observation of the magneto-crystalline easy axes in each individual nanoparticle. Furthermore, the change in the domain orientation with an external magnetic field gives evidence of particle magnetization reversal mediated by a coherent rotation process that is also theoretically predicted by micromagnetic calculations.

  13. Nanoparticle-based flow virometry for the analysis of individual virions.

    PubMed

    Arakelyan, Anush; Fitzgerald, Wendy; Margolis, Leonid; Grivel, Jean-Charles

    2013-09-01

    While flow cytometry has been used to analyze the antigenic composition of individual cells, the antigenic makeup of viral particles is still characterized predominantly in bulk. Here, we describe a technology, "flow virometry," that can be used for antigen detection on individual virions. The technology is based on binding magnetic nanoparticles to virions, staining the virions with monoclonal antibodies, separating the formed complexes with magnetic columns, and characterizing them with flow cytometers. We used this technology to study the distribution of two antigens (HLA-DR and LFA-1) that HIV-1 acquires from infected cells among individual HIV-1 virions. Flow virometry revealed that the antigenic makeup of virions from a single preparation is heterogeneous. This heterogeneity could not be detected with bulk analysis of viruses. Moreover, in two preparations of the same HIV-1 produced by different cells, the distribution of antigens among virions was different. In contrast, HIV-1 of two different HIV-1 genotypes replicating in the same cells became somewhat antigenically similar. This nanotechnology allows the study of virions in bodily fluids without virus propagation and in principle is not restricted to the analysis of HIV, but can be applied to the analysis of the individual surface antigenic makeup of any virus. PMID:23925291

  14. Individual and collective modes of surface magnetoplasmon in thiolate-protected silver nanoparticles studied by MCD spectroscopy

    NASA Astrophysics Data System (ADS)

    Yao, Hiroshi; Shiratsu, Taisuke

    2016-05-01

    Large magneto-optical (MO) responses at the energy of localized surface plasmon resonance (LSPR), namely, surface magnetoplasmons, are demonstrated for the first time in thiolate-protected silver nanoparticles with magnetic circular dichroism (MCD) spectroscopy. The samples examined are decanethiol (DT)-, azobenzenethiol (ABT)-, and ABT/DT mixed-monolayer-protected Ag nanoparticles. ABT-protected Ag nanoparticles are somewhat aggregated and thus exhibit a broad, collective mode of plasmonic absorption, whereas other samples with highly-dispersed nanoparticles show an individual mode of LSPR absorption. In all Ag nanoparticles, a derivative-like MCD signal is observed under an applied magnetic field of 1.6 T, which can be explained in terms of two circular modes of magnetoplasmon caused by the increase (or decrease) in the Lorentz force imparted on the free electrons that oscillate in the left (or right) circular orbits in the nanosphere. For the Ag nanoparticles exhibiting an individual LSPR mode, in particular, simultaneous deconvolution analysis of UV-vis absorption and MCD spectra reveal that (i) the amplitude of the magnetoplasmonic component with lower frequency (ω-), resulting from the reduction in the confinement strength of collective electrons by the Lorentz force, is stronger than that with a higher frequency (ω+) (ii) the accurate shift or cyclotron frequency between two magnetoplasmonic modes (ωc = ω+ - ω-) is size-dependent, and presents a very large value with implications for the apparent enhancement of the local magnetic-field in the Ag nanoparticles. These results strongly suggest that the Ag-thiolate layer or Ag-S bonding on the nanoparticle surface plays a significant role in the MO enhancement.Large magneto-optical (MO) responses at the energy of localized surface plasmon resonance (LSPR), namely, surface magnetoplasmons, are demonstrated for the first time in thiolate-protected silver nanoparticles with magnetic circular dichroism (MCD

  15. Hollow Nanostructured Metal Silicates with Tunable Properties for Lithium Ion Battery Anodes.

    PubMed

    Yu, Seung-Ho; Quan, Bo; Jin, Aihua; Lee, Kug-Seung; Kang, Soon Hyung; Kang, Kisuk; Piao, Yuanzhe; Sung, Yung-Eun

    2015-11-25

    Hollow nanostructured materials have attracted considerable interest as lithium ion battery electrodes because of their good electrochemical properties. In this study, we developed a general procedure for the synthesis of hollow nanostructured metal silicates via a hydrothermal process using silica nanoparticles as templates. The morphology and composition of hollow nanostructured metal silicates could be controlled by changing the metal precursor. The as-prepared hierarchical hollow nanostructures with diameters of ∼100-200 nm were composed of variously shaped primary particles such as hollow nanospheres, solid nanoparticles, and thin nanosheets. Furthermore, different primary nanoparticles could be combined to form hybrid hierarchical hollow nanostructures. When hollow nanostructured metal silicates were applied as anode materials for lithium ion batteries, all samples exhibited good cyclic stability during 300 cycles, as well as tunable electrochemical properties.

  16. Surface interactions of gold nanorods and polysaccharides: From clusters to individual nanoparticles.

    PubMed

    de Barros, Heloise Ribeiro; Piovan, Leandro; Sassaki, Guilherme L; de Araujo Sabry, Diego; Mattoso, Ney; Nunes, Ábner Magalhães; Meneghetti, Mario R; Riegel-Vidotti, Izabel C

    2016-11-01

    Gold nanorods (AuNRs) are suitable for constructing self-assembled structures for the development of biosensing devices and are usually obtained in the presence of cetyltrimethylammonium bromide (CTAB). Here, a sulfated chitosan (ChiS) and gum arabic (GA) were employed to encapsulate CTAB/AuNRs with the purpose of studying the interactions of the polysaccharides with CTAB, which is cytotoxic and is responsible for the instability of nanoparticles in buffer solutions. The presence of a variety of functional groups such as the sulfate groups in ChiS and the carboxylic groups in GA, led to efficient interactions with CTAB/AuNRs as evidenced through UV-vis and FTIR spectroscopies. Electron microscopies (HR-SEM and TEM) revealed that nanoparticle clusters were formed in the GA-AuNRs sample, whereas individual AuNRs, surrounded by a dense layer of polysaccharides, were observed in the ChiS-AuNRs sample. Therefore, the presented work contributes to the understanding of the driving forces that control the surface interactions of the studied materials, providing useful information in the building-up of gold self-assembled nanostructures. PMID:27516295

  17. The 3D-architecture of individual free silver nanoparticles captured by X-ray scattering

    PubMed Central

    Barke, Ingo; Hartmann, Hannes; Rupp, Daniela; Flückiger, Leonie; Sauppe, Mario; Adolph, Marcus; Schorb, Sebastian; Bostedt, Christoph; Treusch, Rolf; Peltz, Christian; Bartling, Stephan; Fennel, Thomas; Meiwes-Broer, Karl-Heinz; Möller, Thomas

    2015-01-01

    The diversity of nanoparticle shapes generated by condensation from gaseous matter reflects the fundamental competition between thermodynamic equilibration and the persistence of metastable configurations during growth. In the kinetically limited regime, intermediate geometries that are favoured only in early formation stages can be imprinted in the finally observed ensemble of differently structured specimens. Here we demonstrate that single-shot wide-angle scattering of femtosecond soft X-ray free-electron laser pulses allows three-dimensional characterization of the resulting metastable nanoparticle structures. For individual free silver particles, which can be considered frozen in space for the duration of photon exposure, both shape and orientation are uncovered from measured scattering images. We identify regular shapes, including species with fivefold symmetry and surprisingly large aspect ratio up to particle radii of the order of 100 nm. Our approach includes scattering effects beyond Born’s approximation and is remarkably efficient—opening up new routes in ultrafast nanophysics and free-electron laser science. PMID:25650004

  18. The 3D-architecture of individual free silver nanoparticles captured by X-ray scattering.

    PubMed

    Barke, Ingo; Hartmann, Hannes; Rupp, Daniela; Flückiger, Leonie; Sauppe, Mario; Adolph, Marcus; Schorb, Sebastian; Bostedt, Christoph; Treusch, Rolf; Peltz, Christian; Bartling, Stephan; Fennel, Thomas; Meiwes-Broer, Karl-Heinz; Möller, Thomas

    2015-01-01

    The diversity of nanoparticle shapes generated by condensation from gaseous matter reflects the fundamental competition between thermodynamic equilibration and the persistence of metastable configurations during growth. In the kinetically limited regime, intermediate geometries that are favoured only in early formation stages can be imprinted in the finally observed ensemble of differently structured specimens. Here we demonstrate that single-shot wide-angle scattering of femtosecond soft X-ray free-electron laser pulses allows three-dimensional characterization of the resulting metastable nanoparticle structures. For individual free silver particles, which can be considered frozen in space for the duration of photon exposure, both shape and orientation are uncovered from measured scattering images. We identify regular shapes, including species with fivefold symmetry and surprisingly large aspect ratio up to particle radii of the order of 100 nm. Our approach includes scattering effects beyond Born's approximation and is remarkably efficient-opening up new routes in ultrafast nanophysics and free-electron laser science. PMID:25650004

  19. The 3D-architecture of individual free silver nanoparticles captured by X-ray scattering

    DOE PAGESBeta

    Barke, Ingo; Hartmann, Hannes; Rupp, Daniela; Flückiger, Leonie; Sauppe, Mario; Adolph, Marcus; Schorb, Sebastian; Bostedt, Christoph; Treusch, Rolf; Peltz, Christian; et al

    2015-02-04

    The diversity of nanoparticle shapes generated by condensation from gaseous matter reflects the fundamental competition between thermodynamic equilibration and the persistence of metastable configurations during growth. In the kinetically limited regime, intermediate geometries that are favoured only in early formation stages can be imprinted in the finally observed ensemble of differently structured specimens. Here we demonstrate that single-shot wide-angle scattering of femtosecond soft X-ray free-electron laser pulses allows three-dimensional characterization of the resulting metastable nanoparticle structures. For individual free silver particles, which can be considered frozen in space for the duration of photon exposure, both shape and orientation are uncoveredmore » from measured scattering images. We identify regular shapes, including species with fivefold symmetry and surprisingly large aspect ratio up to particle radii of the order of 100 nm. Our approach includes scattering effects beyond Born’s approximation and is remarkably efficient—opening up new routes in ultrafast nanophysics and free-electron laser science« less

  20. The 3D-architecture of individual free silver nanoparticles captured by X-ray scattering

    SciTech Connect

    Barke, Ingo; Hartmann, Hannes; Rupp, Daniela; Flückiger, Leonie; Sauppe, Mario; Adolph, Marcus; Schorb, Sebastian; Bostedt, Christoph; Treusch, Rolf; Peltz, Christian; Bartling, Stephan; Fennel, Thomas; Meiwes-Broer, Karl-Heinz; Möller, Thomas

    2015-02-04

    The diversity of nanoparticle shapes generated by condensation from gaseous matter reflects the fundamental competition between thermodynamic equilibration and the persistence of metastable configurations during growth. In the kinetically limited regime, intermediate geometries that are favoured only in early formation stages can be imprinted in the finally observed ensemble of differently structured specimens. Here we demonstrate that single-shot wide-angle scattering of femtosecond soft X-ray free-electron laser pulses allows three-dimensional characterization of the resulting metastable nanoparticle structures. For individual free silver particles, which can be considered frozen in space for the duration of photon exposure, both shape and orientation are uncovered from measured scattering images. We identify regular shapes, including species with fivefold symmetry and surprisingly large aspect ratio up to particle radii of the order of 100 nm. Our approach includes scattering effects beyond Born’s approximation and is remarkably efficient—opening up new routes in ultrafast nanophysics and free-electron laser science

  1. Far-field optical nanothermometry using individual sub-50 nm upconverting nanoparticles.

    PubMed

    Kilbane, Jacob D; Chan, Emory M; Monachon, Christian; Borys, Nicholas J; Levy, Elizabeth S; Pickel, Andrea D; Urban, Jeffrey J; Schuck, P James; Dames, Chris

    2016-06-01

    We demonstrate far-field optical thermometry using individual NaYF4 nanoparticles doped with 2% Er(3+) and 20% Yb(3+). Isolated 20 × 20 × 40 nm(3) particles were identified using only far-field optical imaging, confirmed by subsequent scanning electron microscopy. The luminescence thermometry response for five such single particles was characterized for temperatures from 300 K to 400 K. A standard Arrhenius model widely used for larger particles can still be accurately applied to these sub-50 nm particles, with good particle-to-particle uniformity (response coefficients exhibited standard deviations below 5%). With its spatial resolution on the order of 50 nm when imaging a single particle, far below the diffraction limit, this technique has potential applications for both fundamental thermal measurements and nanoscale metrology in industrial applications. PMID:27216164

  2. Far-field optical nanothermometry using individual sub-50 nm upconverting nanoparticles

    NASA Astrophysics Data System (ADS)

    Kilbane, Jacob D.; Chan, Emory M.; Monachon, Christian; Borys, Nicholas J.; Levy, Elizabeth S.; Pickel, Andrea D.; Urban, Jeffrey J.; Schuck, P. James; Dames, Chris

    2016-06-01

    We demonstrate far-field optical thermometry using individual NaYF4 nanoparticles doped with 2% Er3+ and 20% Yb3+. Isolated 20 × 20 × 40 nm3 particles were identified using only far-field optical imaging, confirmed by subsequent scanning electron microscopy. The luminescence thermometry response for five such single particles was characterized for temperatures from 300 K to 400 K. A standard Arrhenius model widely used for larger particles can still be accurately applied to these sub-50 nm particles, with good particle-to-particle uniformity (response coefficients exhibited standard deviations below 5%). With its spatial resolution on the order of 50 nm when imaging a single particle, far below the diffraction limit, this technique has potential applications for both fundamental thermal measurements and nanoscale metrology in industrial applications.We demonstrate far-field optical thermometry using individual NaYF4 nanoparticles doped with 2% Er3+ and 20% Yb3+. Isolated 20 × 20 × 40 nm3 particles were identified using only far-field optical imaging, confirmed by subsequent scanning electron microscopy. The luminescence thermometry response for five such single particles was characterized for temperatures from 300 K to 400 K. A standard Arrhenius model widely used for larger particles can still be accurately applied to these sub-50 nm particles, with good particle-to-particle uniformity (response coefficients exhibited standard deviations below 5%). With its spatial resolution on the order of 50 nm when imaging a single particle, far below the diffraction limit, this technique has potential applications for both fundamental thermal measurements and nanoscale metrology in industrial applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01479h

  3. Direct quantification of rare earth doped titania nanoparticles in individual human cells.

    PubMed

    Jeynes, J C G; Jeynes, C; Palitsin, V; Townley, H E

    2016-07-15

    There are many possible biomedical applications for titania nanoparticles (NPs) doped with rare earth elements (REEs), from dose enhancement and diagnostic imaging in radiotherapy, to biosensing. However, there are concerns that the NPs could disintegrate in the body thus releasing toxic REE ions to undesired locations. As a first step, we investigate how accurately the Ti/REE ratio from the NPs can be measured inside human cells. A quantitative analysis of whole, unsectioned, individual human cells was performed using proton microprobe elemental microscopy. This method is unique in being able to quantitatively analyse all the elements in an unsectioned individual cell with micron resolution, while also scanning large fields of view. We compared the Ti/REE signal inside cells to NPs that were outside the cells, non-specifically absorbed onto the polypropylene substrate. We show that the REE signal in individual cells co-localises with the titanium signal, indicating that the NPs have remained intact. Within the uncertainty of the measurement, there is no difference between the Ti/REE ratio inside and outside the cells. Interestingly, we also show that there is considerable variation in the uptake of the NPs from cell-to-cell, by a factor of more than 10. We conclude that the NPs enter the cells and remain intact. The large heterogeneity in NP concentrations from cell-to-cell should be considered if they are to be used therapeutically. PMID:27255758

  4. Direct quantification of rare earth doped titania nanoparticles in individual human cells

    NASA Astrophysics Data System (ADS)

    Jeynes, J. C. G.; Jeynes, C.; Palitsin, V.; Townley, H. E.

    2016-07-01

    There are many possible biomedical applications for titania nanoparticles (NPs) doped with rare earth elements (REEs), from dose enhancement and diagnostic imaging in radiotherapy, to biosensing. However, there are concerns that the NPs could disintegrate in the body thus releasing toxic REE ions to undesired locations. As a first step, we investigate how accurately the Ti/REE ratio from the NPs can be measured inside human cells. A quantitative analysis of whole, unsectioned, individual human cells was performed using proton microprobe elemental microscopy. This method is unique in being able to quantitatively analyse all the elements in an unsectioned individual cell with micron resolution, while also scanning large fields of view. We compared the Ti/REE signal inside cells to NPs that were outside the cells, non-specifically absorbed onto the polypropylene substrate. We show that the REE signal in individual cells co-localises with the titanium signal, indicating that the NPs have remained intact. Within the uncertainty of the measurement, there is no difference between the Ti/REE ratio inside and outside the cells. Interestingly, we also show that there is considerable variation in the uptake of the NPs from cell-to-cell, by a factor of more than 10. We conclude that the NPs enter the cells and remain intact. The large heterogeneity in NP concentrations from cell-to-cell should be considered if they are to be used therapeutically.

  5. Site-specific deposition of single gold nanoparticles by individual growth in electrohydrodynamically-printed attoliter droplet reactors

    NASA Astrophysics Data System (ADS)

    Schneider, Julian; Rohner, Patrik; Galliker, Patrick; Raja, Shyamprasad N.; Pan, Ying; Tiwari, Manish K.; Poulikakos, Dimos

    2015-05-01

    Gold nanoparticles with unique electronic, optical and catalytic properties can be efficiently synthesized in colloidal suspensions and are of broad scientific and technical interest and utility. However, their orderly integration on functional surfaces and devices remains a challenge. Here we show that single gold nanoparticles can be directly grown in individually printed, stabilized metal-salt ink attoliter droplets, using a nanoscale electrohydrodynamic printing method with a stable high-frequency dripping mode. This enables controllable sessile droplet nanoreactor formation and sustenance on non-wetting substrates, despite simultaneous rapid evaporation. The single gold nanoparticles can be formed inside such reactors in situ or by subsequent thermal annealing and plasma ashing. With this non-contact technique, single particles with diameters tunable in the range of 5-35 nm and with narrow size distribution, high yield and alignment accuracy are generated on demand and patterned into arbitrary arrays. The nanoparticles feature good catalytic activity as shown by the exemplary growth of silicon nanowires from the nanoparticles and the etching of nanoholes by the printed nanoparticles.Gold nanoparticles with unique electronic, optical and catalytic properties can be efficiently synthesized in colloidal suspensions and are of broad scientific and technical interest and utility. However, their orderly integration on functional surfaces and devices remains a challenge. Here we show that single gold nanoparticles can be directly grown in individually printed, stabilized metal-salt ink attoliter droplets, using a nanoscale electrohydrodynamic printing method with a stable high-frequency dripping mode. This enables controllable sessile droplet nanoreactor formation and sustenance on non-wetting substrates, despite simultaneous rapid evaporation. The single gold nanoparticles can be formed inside such reactors in situ or by subsequent thermal annealing and plasma

  6. Individual and collective modes of surface magnetoplasmon in thiolate-protected silver nanoparticles studied by MCD spectroscopy.

    PubMed

    Yao, Hiroshi; Shiratsu, Taisuke

    2016-06-01

    Large magneto-optical (MO) responses at the energy of localized surface plasmon resonance (LSPR), namely, surface magnetoplasmons, are demonstrated for the first time in thiolate-protected silver nanoparticles with magnetic circular dichroism (MCD) spectroscopy. The samples examined are decanethiol (DT)-, azobenzenethiol (ABT)-, and ABT/DT mixed-monolayer-protected Ag nanoparticles. ABT-protected Ag nanoparticles are somewhat aggregated and thus exhibit a broad, collective mode of plasmonic absorption, whereas other samples with highly-dispersed nanoparticles show an individual mode of LSPR absorption. In all Ag nanoparticles, a derivative-like MCD signal is observed under an applied magnetic field of 1.6 T, which can be explained in terms of two circular modes of magnetoplasmon caused by the increase (or decrease) in the Lorentz force imparted on the free electrons that oscillate in the left (or right) circular orbits in the nanosphere. For the Ag nanoparticles exhibiting an individual LSPR mode, in particular, simultaneous deconvolution analysis of UV-vis absorption and MCD spectra reveal that (i) the amplitude of the magnetoplasmonic component with lower frequency (ω-), resulting from the reduction in the confinement strength of collective electrons by the Lorentz force, is stronger than that with a higher frequency (ω+); (ii) the accurate shift or cyclotron frequency between two magnetoplasmonic modes (ωc = ω+-ω-) is size-dependent, and presents a very large value with implications for the apparent enhancement of the local magnetic-field in the Ag nanoparticles. These results strongly suggest that the Ag-thiolate layer or Ag-S bonding on the nanoparticle surface plays a significant role in the MO enhancement. PMID:27188783

  7. In situ growth of hollow CuNi alloy nanoparticles on reduced graphene oxide nanosheets and their magnetic and catalytic properties

    NASA Astrophysics Data System (ADS)

    Yang, Jinglei; Shen, Xiaoping; Ji, Zhenyuan; Zhou, Hu; Zhu, Guoxing; Chen, Kangmin

    2014-10-01

    Hollow CuNi nanocrystals supported on reduced graphene oxide (RGO-CuNi) are synthesized by in situ co-reduction of Cu2+, Ni2+ and graphene oxide (GO) in a one-pot reaction. The as-synthesized RGO-CuNi nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectrometry, inductively coupled plasma optical emission spectrometry, Raman spectroscopy, and magnetic measurement. It is revealed that hollow CuNi nanocrystals with an average size of about 35.1 nm are uniformly deposited on the surface of RGO nanosheets. The formation mechanism of the hollow CuNi nanostructures is also proposed based on the galvanic displacement reaction. The as-synthesized RGO-CuNi nanocomposite exhibits excellent electrocatalytic performance toward the oxidation of glucose in alkaline media, and also shows superior catalytic activity and recycling stability toward the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). Moreover, the RGO-CuNi catalysts can be easily recollected from the reaction system by an external magnetic field due to their considerable saturation magnetization. It is anticipated that loading hollow nanostructures on RGO sheets would open up a new avenue for developing multifunctional catalysts with low cost and high catalytic performance.

  8. Preparation of hollow TiO2 nanoparticles through TiO2 deposition on polystyrene latex particles and characterizations of their structure and photocatalytic activity

    PubMed Central

    2012-01-01

    In a mixed solvent of water and ethanol, polystyrene/titanium dioxide (PSt/TiO2) composite particles of core-shell structure were prepared by hydrolysis of tetrabutyl titanate in the presence of cationic PSt particles or anionic PSt particles surface-treated using γ-aminopropyl triethoxysilane. Hollow TiO2 particles were obtained through calcination of the PSt/TiO2 core-shell particles to burn off the PSt core or through dissolution of the core by tetrahydrofuran (THF). An alternative process constituted of preheating the PSt/TiO2 particles at 200°C to allow partial crystallization followed by calcination or PSt dissolution by THF. The outcome TiO2 particles thus prepared were examined by TEM, and hollow TiO2 particles were observed. The crystalline phase structure and phase transformation were characterized, which revealed that preheating before the removal of the PSt core was useful to achieve the desired hollow TiO2 particles, and the calcination process was beneficial to the formation of anatase and rutile structures. The tests of TiO2 particles as catalyst in the photodegradation of Rhodamine B demonstrated that a much higher catalytic activity was observed with the TiO2 hollow particles prepared through calcination combined with preheating. PMID:23176612

  9. Biomimetic Branched Hollow Fibers Templated by Self-assembled Fibrous Polyvinylpyrrolidone (PVP) Structures in Aqueous Solution

    PubMed Central

    Qiu, Penghe; Mao, Chuanbin

    2010-01-01

    Branched hollow fibers are common in nature, but to form artificial fibers with a similar branched hollow structure is still a challenge. We discovered that polyvinylpyrrolidone (PVP) could self-assemble into branched hollow fibers in an aqueous solution after aging the PVP solution for about two weeks. Based on this finding, we demonstrated two approaches by which the self-assembly of PVP into branched hollow fibers could be exploited to template the formation of branched hollow inorganic fibers. First, inorganic material such as silica with high affinity against the PVP could be deposited on the surface of the branched hollow PVP fibers to form branched hollow silica fibers. To extend the application of PVP self-assembly in templating the formation of hollow branched fibers, we then adopted a second approach where the PVP molecules bound to inorganic nanoparticles (using gold nanoparticles as a model) co-self-assemble with the free PVP molecules in an aqueous solution, resulting in the formation of the branched hollow fibers with the nanoparticles embedded in the PVP matrix constituting the walls of the fibers. Heating the resultant fibers above the glass transition temperature of PVP led to the formation of branched hollow gold fibers. Our work suggests that the self-assembly of the PVP molecules in the solution can serve as a general method for directing the formation of branched hollow inorganic fibers. The branched hollow fibers may find potential applications in microfluidics, artificial blood vessel generation, and tissue engineering. PMID:20158250

  10. Photochemical Fixation of Individual Polymer Nanoparticles on Glass Substrates in Solution at Room Temperature

    NASA Astrophysics Data System (ADS)

    Ito, Syoji; Yoshikawa, Hiroyuki; Masuhara, Hiroshi

    2004-07-01

    A new method for fixing single polymer nanoparticles onto a substrate was developed by local photopolymerization. A nanoparticle, dispersed in ethylene glycol containing monomer, crosslinker, and radical photoinitiator, was moved to the surface of a glass substrate using a focused near-infrared laser beam. Local photopolymerization around the nanoparticle was induced by additional irradiation of an ultraviolet pulsed laser beam, resulting in the generation of an acrylamide gel containing the nanoparticle on the substrate. The nanoparticles become fixed and remained after washing. The morphology of the formed polymerized gel was evaluated by atomic force microscope (AFM) observation.

  11. Resistive Switching of Individual, Chemically Synthesized TiO2 Nanoparticles.

    PubMed

    Schmidt, Dirk Oliver; Hoffmann-Eifert, Susanne; Zhang, Hehe; La Torre, Camilla; Besmehn, Astrid; Noyong, Michael; Waser, Rainer; Simon, Ulrich

    2015-12-22

    Resistively switching devices are considered promising for next-generation nonvolatile random-access memories. Today, such memories are fabricated by means of "top-down approaches" applying thin films sandwiched between nanoscaled electrodes. In contrast, this work presents a "bottom-up approach" disclosing for the first time the resistive switching (RS) of individual TiO2 nanoparticles (NPs). The NPs, which have sizes of 80 and 350 nm, respectively, are obtained by wet chemical synthesis and thermally treated under oxidizing or vacuum conditions for crystallization, respectively. These NPs are deposited on a Pt/Ir bottom electrode and individual NPs are electrically characterized by means of a nanomanipulator system in situ, in a scanning electron microscope. While amorphous NPs and calcined NPs reveal no switching hysteresis, a very interesting behavior is found for the vacuum-annealed, crystalline TiO(2-x) NPs. These NPs reveal forming-free RS behavior, dominantly complementary switching (CS) and, to a small degree, bipolar switching (BS) characteristics. In contrast, similarly vacuum-annealed TiO2 thin films grown by atomic layer deposition show standard BS behavior under the same conditions. The interesting CS behavior of the TiO(2-x) NPs is attributed to the formation of a core-shell-like structure by re-oxidation of the reduced NPs as a unique feature.

  12. Superior hydrogen desorption kinetics of Mg(NH{sub 2}){sub 2} hollow nanospheres mixed with MgH{sub 2} nanoparticles

    SciTech Connect

    Xie Lei; Li Yaoqi; Yang Rong; Liu Yang; Li Xingguo

    2008-06-09

    Mg{sub 3}N{sub 2} nanocubes were prepared by vaporized bulk magnesium in ammonia atmosphere associated with plasma metal reaction. Then the product transformed to Mg(NH{sub 2}){sub 2} hollow nanospheres after it was reacted with NH{sub 3} based on the Kirkendall effect. The electron microscopy results suggested that the obtained hollow nanospheres were around 100 nm and the shell thickness was about 10 nm. Because of its short distance for Mg{sup 2+} diffusion and large specific surface area for interaction between Mg(NH{sub 2}){sub 2} and MgH{sub 2}, the structure dramatically enhanced the hydrogen desorption kinetics of Mg(NH{sub 2}){sub 2}-2MgH{sub 2}.

  13. Volatile-nanoparticle-assisted optical visualization of individual carbon nanotubes and other nanomaterials.

    PubMed

    Jian, Muqiang; Xie, Huanhuan; Wang, Qi; Xia, Kailun; Yin, Zhe; Zhang, Mingyu; Deng, Ningqin; Wang, Luning; Ren, Tianling; Zhang, Yingying

    2016-07-21

    The development of nanomaterials has put forward high requirements for characterization techniques. Optical microscopy (OM), with easy accessibility and open operating spaces as compared to scanning electron microscopy, is a good choice to quickly locate materials and to be integrated with other equipment. However, OM is limited by its low resolution. Herein, we present a facile and non-destructive approach for optical observation of nanomaterials under conventional OMs with the aid of volatile nanoparticles (NPs), which can be deposited and removed in a controlled manner. The NPs deposited on the surface of nanomaterials render strong light scattering to enable the nanomaterials to become optically visible. For example, this approach enables the observation of individual carbon nanotubes (CNTs) with OMs at low magnification or even with the naked eye. Both supported CNTs on various substrates and suspended CNTs can be observed with this approach. Most importantly, the NPs can be completely removed through moderate heat treatment or laser irradiation, avoiding potential influence on the properties or subsequent applications of nanomaterials. Furthermore, we systematically investigate the deposition of various volatile NPs (up to 14 kinds) for the optical observation of nanomaterials. We also demonstrated the application of this approach on other nanomaterials, including nanowires and graphene. We showed that this approach is facile, controllable, non-destructive, and contamination-free, indicating wide potential applications. PMID:27350415

  14. Avalanching strain dynamics during the hydriding phase transformation in individual palladium nanoparticles

    SciTech Connect

    Ulvestad, A.; Welland, M. J.; Collins, S. S. E.; Harder, R.; Maxey, E.; Wingert, J.; Singer, A.; Hy, S.; Mulvaney, P.; Zapol, P.; Shpyrko, O. G.

    2015-12-11

    Phase transitions in reactive environments are crucially important in energy and information storage, catalysis and sensors. Nanostructuring active particles can yield faster charging/ discharging kinetics, increased lifespan and record catalytic activities. However, establishing the causal link between structure and function is challenging for nanoparticles, as ensemble measurements convolve intrinsic single-particle properties with sample diversity. Here we study the hydriding phase transformation in individual palladium nanocubes in situ using coherent X-ray diffractive imaging. The phase transformation dynamics, which involve the nucleation and propagation of a hydrogen-rich region, are dependent on absolute time (aging) and involve intermittent dynamics (avalanching). A hydrogen-rich surface layer dominates the crystal strain in the hydrogen-poor phase, while strain inversion occurs at the cube corners in the hydrogen-rich phase. A three-dimensional phase-field model is used to interpret the experimental results. In conclusion, our experimental and theoretical approach provides a general framework for designing and optimizing phase transformations for single nanocrystals in reactive environments.

  15. Avalanching strain dynamics during the hydriding phase transformation in individual palladium nanoparticles

    DOE PAGESBeta

    Ulvestad, A.; Welland, M. J.; Collins, S. S. E.; Harder, R.; Maxey, E.; Wingert, J.; Singer, A.; Hy, S.; Mulvaney, P.; Zapol, P.; et al

    2015-12-11

    Phase transitions in reactive environments are crucially important in energy and information storage, catalysis and sensors. Nanostructuring active particles can yield faster charging/ discharging kinetics, increased lifespan and record catalytic activities. However, establishing the causal link between structure and function is challenging for nanoparticles, as ensemble measurements convolve intrinsic single-particle properties with sample diversity. Here we study the hydriding phase transformation in individual palladium nanocubes in situ using coherent X-ray diffractive imaging. The phase transformation dynamics, which involve the nucleation and propagation of a hydrogen-rich region, are dependent on absolute time (aging) and involve intermittent dynamics (avalanching). A hydrogen-rich surfacemore » layer dominates the crystal strain in the hydrogen-poor phase, while strain inversion occurs at the cube corners in the hydrogen-rich phase. A three-dimensional phase-field model is used to interpret the experimental results. In conclusion, our experimental and theoretical approach provides a general framework for designing and optimizing phase transformations for single nanocrystals in reactive environments.« less

  16. Avalanching strain dynamics during the hydriding phase transformation in individual palladium nanoparticles

    PubMed Central

    Ulvestad, A.; Welland, M. J.; Collins, S. S. E.; Harder, R.; Maxey, E.; Wingert, J.; Singer, A.; Hy, S.; Mulvaney, P.; Zapol, P.; Shpyrko, O. G.

    2015-01-01

    Phase transitions in reactive environments are crucially important in energy and information storage, catalysis and sensors. Nanostructuring active particles can yield faster charging/discharging kinetics, increased lifespan and record catalytic activities. However, establishing the causal link between structure and function is challenging for nanoparticles, as ensemble measurements convolve intrinsic single-particle properties with sample diversity. Here we study the hydriding phase transformation in individual palladium nanocubes in situ using coherent X-ray diffractive imaging. The phase transformation dynamics, which involve the nucleation and propagation of a hydrogen-rich region, are dependent on absolute time (aging) and involve intermittent dynamics (avalanching). A hydrogen-rich surface layer dominates the crystal strain in the hydrogen-poor phase, while strain inversion occurs at the cube corners in the hydrogen-rich phase. A three-dimensional phase-field model is used to interpret the experimental results. Our experimental and theoretical approach provides a general framework for designing and optimizing phase transformations for single nanocrystals in reactive environments. PMID:26655832

  17. Individual and binary toxicity of anatase and rutile nanoparticles towards Ceriodaphnia dubia.

    PubMed

    Iswarya, V; Bhuvaneshwari, M; Chandrasekaran, N; Mukherjee, Amitava

    2016-09-01

    Increasing usage of engineered nanoparticles, especially Titanium dioxide (TiO2) in various commercial products has necessitated their toxicity evaluation and risk assessment, especially in the aquatic ecosystem. In the present study, a comprehensive toxicity assessment of anatase and rutile NPs (individual as well as a binary mixture) has been carried out in a freshwater matrix on Ceriodaphnia dubia under different irradiation conditions viz., visible and UV-A. Anatase and rutile NPs produced an LC50 of about 37.04 and 48mg/L, respectively, under visible irradiation. However, lesser LC50 values of about 22.56 (anatase) and 23.76 (rutile) mg/L were noted under UV-A irradiation. A toxic unit (TU) approach was followed to determine the concentrations of binary mixtures of anatase and rutile. The binary mixture resulted in an antagonistic and additive effect under visible and UV-A irradiation, respectively. Among the two different modeling approaches used in the study, Marking-Dawson model was noted to be a more appropriate model than Abbott model for the toxicity evaluation of binary mixtures. The agglomeration of NPs played a significant role in the induction of antagonistic and additive effects by the mixture based on the irradiation applied. TEM and zeta potential analysis confirmed the surface interactions between anatase and rutile NPs in the mixture. Maximum uptake was noticed at 0.25 total TU of the binary mixture under visible irradiation and 1 TU of anatase NPs for UV-A irradiation. Individual NPs showed highest uptake under UV-A than visible irradiation. In contrast, binary mixture showed a difference in the uptake pattern based on the type of irradiation exposed. PMID:27522033

  18. Combination of Microporous Hollow Carbon Spheres and Nafion for the Individual Metal-free Stripping Detection of Pb(2+) and Cd(2.).

    PubMed

    Niu, Xiangheng; Zhang, Hongwei; Yu, Meihua; Zhao, Hongli; Lan, Minbo; Yu, Chengzhong

    2016-01-01

    Here, the combination of Nafion with microporous hollow carbon spheres (MHCS) is first proposed to fabricate a disposable metal-free electrode for heavy metal stripping sensing. The MHCS-Nafion composite film electrode is prepared by drop-casting a mixture of MHCS and Nafion onto the lab-made screen-printed carbon electrode (SPCE(*)). Results demonstrate that the interfusion of MHCS into Nafion offers enhanced performance for the electro-enrichment and stripping of lead and cadmium over the only Nafion film: 1) abundant MHCS immobilized on the electrode surface serve as effective nucleation sites for metal ion reduction; 2) the mixing of MHCS into Nafion enlarges the active surface of negative-charged Nafion for the electrostatic adsorption of metal cations. The proposed MHCS-Nafion/SPCE(*) provides linear responses for Pb(2+) and Cd(2+) in the range of 2 - 200 μg/L, with a detection limit of 1.37 and 1.63 μg/L, respectively. Practical applications of the sensor in water sample detection with good accuracy have also been confirmed.

  19. Combination of Microporous Hollow Carbon Spheres and Nafion for the Individual Metal-free Stripping Detection of Pb(2+) and Cd(2.).

    PubMed

    Niu, Xiangheng; Zhang, Hongwei; Yu, Meihua; Zhao, Hongli; Lan, Minbo; Yu, Chengzhong

    2016-01-01

    Here, the combination of Nafion with microporous hollow carbon spheres (MHCS) is first proposed to fabricate a disposable metal-free electrode for heavy metal stripping sensing. The MHCS-Nafion composite film electrode is prepared by drop-casting a mixture of MHCS and Nafion onto the lab-made screen-printed carbon electrode (SPCE(*)). Results demonstrate that the interfusion of MHCS into Nafion offers enhanced performance for the electro-enrichment and stripping of lead and cadmium over the only Nafion film: 1) abundant MHCS immobilized on the electrode surface serve as effective nucleation sites for metal ion reduction; 2) the mixing of MHCS into Nafion enlarges the active surface of negative-charged Nafion for the electrostatic adsorption of metal cations. The proposed MHCS-Nafion/SPCE(*) provides linear responses for Pb(2+) and Cd(2+) in the range of 2 - 200 μg/L, with a detection limit of 1.37 and 1.63 μg/L, respectively. Practical applications of the sensor in water sample detection with good accuracy have also been confirmed. PMID:27682398

  20. Nano electrochemical reactors of Fe2O3 nanoparticles embedded in shells of nitrogen-doped hollow carbon spheres as high-performance anodes for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Zheng, Fangcai; He, Mengni; Yang, Yang; Chen, Qianwang

    2015-02-01

    Iron oxides are extensively investigated as anode materials for lithium-ion batteries (LIBs) because of their large specific capacities. However, they undergo huge volume changes during cycling that result in anode pulverization and loss of electrical connectivity. As a result, the capacity retention of the iron oxide anodes is poor and should be improved for commercial applications. Herein, we report the preparation of ultrasmall Fe2O3 nanoparticles embedded in nitrogen-doped hollow carbon sphere shells (Fe2O3@N-C) by the direct pyrolysis of Fe-based zeolitic imidazolate frameworks (Fe-ZIF) at 620 °C in air. As an anode material for LIBs, the capacity retained was 1573 mA h g-1 after 50 cycles at a current density of 0.1 C (1 C = 1000 mA g-1). Even undergoing the high-rate capability test twice, it can still deliver a remarkably reversible and stable capacity of 1142 mA h g-1 after 100 cycles at a current density of 1 C. The excellent electrochemical performance is attributed to the unique structure of ultrasmall Fe2O3 nanoparticles uniformly distributed in the shell of nitrogen-doped carbon spheres, which simultaneously solve the major problems of pulverization, facilitate rapid electrochemical kinetics, and effectively avoid the aggregation of Fe2O3 nanoparticles during de/lithiation. The novel method developed in this work for the synthesis of functional hybrid materials can be extended to the preparation of various MOFs-derived functional nanocomposites owing to the versatility of links and metal centers in MOFs.Iron oxides are extensively investigated as anode materials for lithium-ion batteries (LIBs) because of their large specific capacities. However, they undergo huge volume changes during cycling that result in anode pulverization and loss of electrical connectivity. As a result, the capacity retention of the iron oxide anodes is poor and should be improved for commercial applications. Herein, we report the preparation of ultrasmall Fe2O3 nanoparticles

  1. Volatile-nanoparticle-assisted optical visualization of individual carbon nanotubes and other nanomaterials

    NASA Astrophysics Data System (ADS)

    Jian, Muqiang; Xie, Huanhuan; Wang, Qi; Xia, Kailun; Yin, Zhe; Zhang, Mingyu; Deng, Ningqin; Wang, Luning; Ren, Tianling; Zhang, Yingying

    2016-07-01

    The development of nanomaterials has put forward high requirements for characterization techniques. Optical microscopy (OM), with easy accessibility and open operating spaces as compared to scanning electron microscopy, is a good choice to quickly locate materials and to be integrated with other equipment. However, OM is limited by its low resolution. Herein, we present a facile and non-destructive approach for optical observation of nanomaterials under conventional OMs with the aid of volatile nanoparticles (NPs), which can be deposited and removed in a controlled manner. The NPs deposited on the surface of nanomaterials render strong light scattering to enable the nanomaterials to become optically visible. For example, this approach enables the observation of individual carbon nanotubes (CNTs) with OMs at low magnification or even with the naked eye. Both supported CNTs on various substrates and suspended CNTs can be observed with this approach. Most importantly, the NPs can be completely removed through moderate heat treatment or laser irradiation, avoiding potential influence on the properties or subsequent applications of nanomaterials. Furthermore, we systematically investigate the deposition of various volatile NPs (up to 14 kinds) for the optical observation of nanomaterials. We also demonstrated the application of this approach on other nanomaterials, including nanowires and graphene. We showed that this approach is facile, controllable, non-destructive, and contamination-free, indicating wide potential applications.The development of nanomaterials has put forward high requirements for characterization techniques. Optical microscopy (OM), with easy accessibility and open operating spaces as compared to scanning electron microscopy, is a good choice to quickly locate materials and to be integrated with other equipment. However, OM is limited by its low resolution. Herein, we present a facile and non-destructive approach for optical observation of

  2. Plasmonic Field Enhancement of Individual Nanoparticles by Correlated Scanning and Photoemission Electron Microscopy

    SciTech Connect

    Peppernick, Samuel J.; Joly, Alan G.; Beck, Kenneth M.; Hess, Wayne P.

    2011-01-21

    We present results of a combined two-photon photoemission and scanning electron microscopy investigation to determine the electromagnetic enhancement factors of silver-coated spherical nanoparticles deposited on an atomically flat mica substrate. Femtosecond laser excitation, of the nanoparticles, produces intense photoemission, attributed to near-resonant excitation of localized surface plasmons. Enhancement factors are determined by comparing the respective two-photon photoemission yield measured for equal areas between single nanoparticles to that of the surrounding flat surface. For s-polarized, 400 nm (~ 3.1 eV) femtosecond radiation a distribution of enhancement factors are found with a large percentage (77%) of the nanoparticles falling within a median range. A correlated scanning electron microscopy analysis demonstrated that the nanoparticles typifying the median of the distribution were characterized by ideal spherical shapes and defect-free morphologies. The single largest enhancement factors were in contrast produced by a very small percentage (8%) of the total, for which evidence of silver defect anomalies were found that contributed to the overall structure of the nanoparticle. Comparisons are made between the experimentally measured enhancement factors and previously reported theoretical predictions of the localized surface plasmon near-field intensities for isolated nanometer-sized silver spheres.

  3. Hollow lensing duct

    DOEpatents

    Beach, Raymond J.; Honea, Eric C.; Bibeau, Camille; Mitchell, Scott; Lang, John; Maderas, Dennis; Speth, Joel; Payne, Stephen A.

    2000-01-01

    A hollow lensing duct to condense (intensify) light using a combination of focusing using a spherical or cylindrical lens followed by reflective waveguiding. The hollow duct tapers down from a wide input side to a narrow output side, with the input side consisting of a lens that may be coated with an antireflective coating for more efficient transmission into the duct. The inside surfaces of the hollow lens duct are appropriately coated to be reflective, preventing light from escaping by reflection as it travels along the duct (reflective waveguiding). The hollow duct has various applications for intensifying light, such as in the coupling of diode array pump light to solid state lasing materials.

  4. Energy Dispersive X-ray Tomography for 3D Elemental Mapping of Individual Nanoparticles

    PubMed Central

    Slater, Thomas J. A.; Lewis, Edward A.; Haigh, Sarah J.

    2016-01-01

    Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial resolution, and is even capable of providing atomically resolved elemental maps. In this technique, a highly focused electron beam is incident upon a thin sample and the energy of emitted X-rays is measured in order to determine the atomic species of material within the beam path. This elementally sensitive spectroscopy technique can be extended to three dimensional tomographic imaging by acquiring multiple spectrum images with the sample tilted along an axis perpendicular to the electron beam direction. Elemental distributions within single nanoparticles are often important for determining their optical, catalytic and magnetic properties. Techniques such as X-ray tomography and slice and view energy dispersive X-ray mapping in the scanning electron microscope provide elementally sensitive three dimensional imaging but are typically limited to spatial resolutions of > 20 nm. Atom probe tomography provides near atomic resolution but preparing nanoparticle samples for atom probe analysis is often challenging. Thus, elementally sensitive techniques applied within the scanning transmission electron microscope are uniquely placed to study elemental distributions within nanoparticles of dimensions 10-100 nm. Here, energy dispersive X-ray (EDX) spectroscopy within the STEM is applied to investigate the distribution of elements in single AgAu nanoparticles. The surface segregation of both Ag and Au, at different nanoparticle compositions, has been observed. PMID:27403838

  5. Nanosized aluminum nitride hollow spheres formed through a self-templating solid-gas interface reaction

    SciTech Connect

    Zheng Jie Song Xubo; Zhang Yaohua; Li Yan; Li Xingguo; Pu Yikang

    2007-01-15

    Nanosized aluminum nitride hollow spheres were synthesized by simply heating aluminum nanoparticles in ammonia at 1000 deg. C. The as-synthesized sphere shells are polycrystalline with cavity diameters ranging from 15 to 100 nm and shell thickness from 5 to 15 nm. The formation mechanism can be explained by the nanoscale Kirkendall effect, which results from the difference in diffusion rates between aluminum and nitrogen. The Al nanoparticles served as both reactant and templates for the hollow sphere formation. The effects of precursor particle size and temperature were also investigated in terms of product morphology. Room temperature cathode luminescence spectrum of the nanosized hollow spheres showed a broad emission band centered at 415 nm, which is originated from oxygen related luminescence centers. The hollow structure survived a 4-h heat treatment at 1200 deg. C, exhibiting excellent thermal stability. - Graphical abstract: Nanosized aluminum nitride hollow spheres were synthesized by nitridation of aluminum nanoparticles at 1000 deg. C using ammonia.

  6. Multi-shelled CeO₂ hollow microspheres as superior photocatalysts for water oxidation.

    PubMed

    Qi, Jian; Zhao, Kun; Li, Guodong; Gao, Yan; Zhao, Huijun; Yu, Ranbo; Tang, Zhiyong

    2014-04-21

    A general self-templating method is introduced to construct triple-shelled CeO₂ hollow microspheres, which are composed of tiny CeO₂ nanoparticles. When the triple-shelled CeO₂ hollow microspheres are used as photocatalysts for direct water oxidation with AgNO₃ as the electron scavenger, excellent activity and enhanced stability for O₂ evolution are achieved, in contrast with commercial CeO₂ nanoparticles, single-shelled CeO₂ hollow microspheres and double-shelled CeO₂ hollow microspheres. Such an outstanding performance is attributed to the unique properties of the triple-shelled CeO₂ hollow microspheres including more efficient multiple reflections of the incident light by the inner shells, the larger surface area and more active sites for improving separation of electron-hole pairs, and the more curved surfaces unfavorable for deposition of in situ generated Ag nanoparticles.

  7. Production of hollow aerogel microspheres

    DOEpatents

    Upadhye, Ravindra S.; Henning, Sten A.

    1993-01-01

    A method is described for making hollow aerogel microspheres of 800-1200 .mu. diameter and 100-300 .mu. wall thickness by forming hollow alcogel microspheres during the sol/gel process in a catalytic atmosphere and capturing them on a foam surface containing catalyst. Supercritical drying of the formed hollow alcogel microspheres yields hollow aerogel microspheres which are suitable for ICF targets.

  8. Production of hollow aerogel microspheres

    SciTech Connect

    Upadhye, R.S.; Henning, S.A.

    1990-12-31

    A method is described for making hollow aerogel microspheres of 800--1200{mu} diameter and 100--300{mu} wall thickness by forming hollow alcogel microspheres during the sol/gel process in a catalytic atmosphere and capturing them on a foam surface containing catalyst. Supercritical drying of the formed hollow alcogel microspheres yields hollow aerogel microspheres which are suitable for ICF targets.

  9. Application of Analyte Harvesting Nanoparticle Technology to the Measurement of Urinary HGH in Healthy Individuals.

    PubMed

    Luchini, Alessandra; Tamburro, Davide; Magni, Ruben; Fredolini, Claudia; Espina, Virginia; Bosch, Jaume; Garaci, Enrico; Petricoin, Emanuel F; Liotta, Lance A

    2012-01-01

    Urine represents a valuable biofluid for noninvasive measurement of Human Growth Hormone (HGH) secretion. Unfortunately, currently available commercial HGH immunoassays do not achieve the sensitivity needed for urinary HGH measurement in the low picogram per milliliter range, the expected normal concentration range of HGH in urine. A nanotechnology based sample preprocessing step was used to extract and concentrate HGH in urine so that urinary HGH could be measured with a clinical grade standard immunoassay designed for serum (Immulite 1000, Siemens). We applied the nanoparticle enhanced immunoassay to evaluate the baseline value of urinary HGH in a population of healthy young adults (age 18-30, N=33, median 21, M: F=39%:61%, with no reported medical therapies). Nanoparticle sample preprocessing effectively improved the lower limit of detection of the Immulite HGH assay by more than 50 fold, shifting the linear range of the assay to encompass the expected value of urinary HGH. The full process between run and within run CV% was 7.9 and 9.0%, respectively. On 33 healthy volunteers, the 95% reference values for hGH in spot urine normalized to specific gravity were 0.64 - 16.85 pg/mL (0.05-5.82 ng/g creatinine). Nanoparticle preprocessing constitutes a reliable means of measuring urinary HGH with a clinical grade immunoassay, now establishing a normal baseline value for HGH in urine. Nanoparticles can be used to study the kinetics of HGH excretion in urine, and the factors that influence urinary HGH secretion and HGH isoform proportions.

  10. Oil Phase Evaporation Induced Self-Assembly of Hydrophobic Nanoparticles into Spherical Clusters with Controlled Surface Chemistry in an Oil-in-Water Dispersion and Comparison of Behaviors of Individual and Clustered Iron Oxide Nanoparticles

    PubMed Central

    Qiu, Penghe; Jensen, Christina; Charity, Njoku; Towner, Rheal; Mao, Chuanbin

    2010-01-01

    We report a general method for preparing nanoparticle clusters (NPCs) in an oil-in-water emulsion system mediated by cetyl trimethylammonium bromide (CTAB) where previously, only individual nanoparticles were obtained. NPCs of magnetic, metallic and semiconductor nanoparticles have been prepared to demonstrate the generality of the method. The NPCs were spherical and composed of densely packed individual nanoparticles. The number density of nanoparticles in the oil phase was found to be critical for the formation, morphology and yield of NPCs. The method developed here is scalable and can produce NPCs in nearly 100% yield at a concentration of 5 mg/ml in water which is approximately 5 times higher than the highest value reported in literature. The surface chemistry of NPCs can also be controlled by replacing CTAB with polymers containing different functional groups via a similar procedure. The reproducible production of NPCs with well defined shapes has allowed us to compare the properties of individual and clustered iron oxide nanoparticles including magnetization, magnetic moments and contrast enhancement in magnetic resonance imaging (MRI). We found that due to their collective properties, NPCs are more responsive to an external magnetic field and can potentially serve as better contrast enhancement agents than individually dispersed magnetic NPs in MRI. PMID:21117657

  11. Hollow-Fiber Clinostat

    NASA Technical Reports Server (NTRS)

    Rhodes, Percy H.; Miller, Teresa Y.; Snyder, Robert S.

    1990-01-01

    Hollow-fiber clinostat, is bioreactor used to study growth and other behavior of cells in simulated microgravity. Cells under study contained in porous hollow fiber immersed in culture medium inside vessel. Bores in hollow fiber allow exchange of gases, nutrients, and metabolic waste products between living cells and external culture media. Hollow fiber lies on axis of vessel, rotated by motor equipped with torque and speed controls. Desired temperature maintained by operating clinostat in standard tissue-culture incubator. Axis of rotation made horizontal or vertical. Designed for use with conventional methods of sterilization and sanitation to prevent contamination of specimen. Also designed for asepsis in assembly, injection of specimen, and exchange of medium.

  12. Hollow metal nanostructures for enhanced plasmonics (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Genç, Aziz; Patarroyo, Javier; Sancho-Parramon, Jordi; Duchamp, Martial; Gonzalez, Edgar; Bastus, Neus G.; Houben, Lothar; Dunin-Borkowski, Rafal; Puntes, Victor F.; Arbiol, Jordi

    2016-03-01

    Complex metal nanoparticles offer a great playground for plasmonic nanoengineering, where it is possible to cover plasmon resonances from ultraviolet to near infrared by modifying the morphologies from solid nanocubes to nanoframes, multiwalled hollow nanoboxes or even nanotubes with hybrid (alternating solid and hollow) structures. We experimentally show that structural modifications, i.e. void size and final morphology, are the dominant determinants for the final plasmonic properties, while compositional variations allow us to get a fine tuning. EELS mappings of localized surface plasmon resonances (LSPRs) reveal an enhanced plasmon field inside the voids of hollow AuAg nanostructures along with a more homogeneous distributions of the plasmon fields around the nanostructures. With the present methodology and the appropriate samples we are able to compare the effects of hybridization at the nanoscale in hollow nanostructures. Boundary element method (BEM) simulations also reveal the effects of structural nanoengineering on plasmonic properties of hollow metal nanostructures. Possibility of tuning the LSPR properties of hollow metal nanostructures in a wide range of energy by modifying the void size/shell thickness is shown by BEM simulations, which reveals that void size is the dominant factor for tuning the LSPRs. As a proof of concept for enhanced plasmonic properties, we show effective label free sensing of bovine serum albumin (BSA) with some of our hollow nanostructures. In addition, the different plasmonic modes observed have also been studied and mapped in 3D.

  13. Hollow cathode apparatus

    NASA Technical Reports Server (NTRS)

    Aston, G. (Inventor)

    1984-01-01

    A hollow cathode apparatus is described, which can be rapidly and reliably started. An ignitor positioned upstream from the hollow cathode, generates a puff of plasma that flows with the primary gas to be ionized through the cathode. The plasma puff creates a high voltage breakdown between the downstream end of the cathode and a keeper electrode, to heat the cathode to an electron-emitting temperature.

  14. Micro hollow cathode discharges

    SciTech Connect

    Schoenbach, K.H.; Peterkin, F.E.; Verhappen, R.

    1995-12-31

    Hollow cathode discharges are glow discharges with the cathode fall and negative glow confined in a cavity in the cathode. For the discharge to develop, the cathode hole dimensions must be on the order of the mean free path. By reducing the cathode hole dimensions it is therefore possible to increase the pressure. Stable hollow cathode discharges in air have been observed at almost one atmosphere when the cathode diameter was reduced to 20 micrometers. In order to study the electrical parameters of a micro hollow cathode discharge, a set of experiments has been performed in argon at pressures in the torr range and a cathode hole diameter of 0.7 mm in molybdenum. The current-voltage characteristics and the appearance of the discharge plasma showed two distinct regions. At lower voltage or pressure the current varies linearly with voltage and the hollow cathode plasma is concentrated around the axis of the cathode hole (low glow mode). At higher values of voltage or pressure the current increases nonlinearly, up to a point where a transition into a low voltage hollow cathode arc was observed, and the plasma column expands and fills almost the entire cathode hole (high glow mode). Spectral measurements showed that the transition from the low glow mode into the high glow mode is related to an increased density of electrode vapor in the hollow cathode discharge. Up to the breakdown into a hollow cathode arc, the current voltage characteristic of the discharge has a positive slope. In this range, hollow cathode discharges can be operated in parallel without a ballast resistor.

  15. Toward full spectrum speciation of silver nanoparticles and ionic silver by on-line coupling of hollow fiber flow field-flow fractionation and minicolumn concentration with multiple detectors.

    PubMed

    Tan, Zhi-Qiang; Liu, Jing-Fu; Guo, Xiao-Ru; Yin, Yong-Guang; Byeon, Seul Kee; Moon, Myeong Hee; Jiang, Gui-Bin

    2015-08-18

    The intertransformation of silver nanoparticles (AgNPs) and ionic silver (Ag(I)) in the environment determines their transport, uptake, and toxicity, demanding methods to simultaneously separate and quantify AgNPs and Ag(I). For the first time, hollow fiber flow field-flow fractionation (HF5) and minicolumn concentration were on-line coupled together with multiple detectors (including UV-vis spectrometry, dynamic light scattering, and inductively coupled plasma mass spectrometry) for full spectrum separation, characterization, and quantification of various Ag(I) species (i.e., free Ag(I), weak and strong Ag(I) complexes) and differently sized AgNPs. While HF5 was employed for filtration and fractionation of AgNPs (>2 nm), the minicolumn packed with Amberlite IR120 resin functioned to trap free Ag(I) or weak Ag(I) complexes coming from the radial flow of HF5 together with the strong Ag(I) complexes and tiny AgNPs (<2 nm), which were further discriminated in a second run of focusing by oxidizing >90% of tiny AgNPs to free Ag(I) and trapped in the minicolumn. The excellent performance was verified by the good agreement of the characterization results of AgNPs determined by this method with that by transmission electron microscopy, and the satisfactory recoveries (70.7-108%) for seven Ag species, including Ag(I), the adduct of Ag(I) and cysteine, and five AgNPs with nominal diameters of 1.4 nm, 10 nm, 20 nm, 40 nm, and 60 nm in surface water samples. PMID:26222150

  16. Quantitatively probing the magnetic behavior of individual nanoparticles by an AC field-modulated magnetic force microscopy

    PubMed Central

    Li, Xiang; Lu, Wei; Song, Yiming; Wang, Yuxin; Chen, Aiying; Yan, Biao; Yoshimura, Satoru; Saito, Hitoshi

    2016-01-01

    Despite decades of advances in magnetic imaging, obtaining direct, quantitative information with nanometer scale spatial resolution remains an outstanding challenge. Current approaches, for example, Hall micromagnetometer and nitrogen-vacancy magnetometer, are limited by highly complex experimental apparatus and a dedicated sample preparation process. Here we present a new AC field-modulated magnetic force microscopy (MFM) and report the local and quantitative measurements of the magnetic information of individual magnetic nanoparticles (MNPs), which is one of the most iconic objects of nanomagnetism. This technique provides simultaneously a direct visualization of the magnetization process of the individual MNPs, with spatial resolution and magnetic sensitivity of about 4.8 nm and 1.85 × 10−20 A m2, respectively, enabling us to separately estimate the distributions of the dipolar fields and the local switching fields of individual MNPs. Moreover, we demonstrate that quantitative magnetization moment of individual MNPs can be routinely obtained using MFM signals. Therefore, it underscores the power of the AC field-modulated MFM for biological and biomedical applications of MNPs and opens up the possibility for directly and quantitatively probing the weak magnetic stray fields from nanoscale magnetic systems with superior spatial resolution. PMID:26932357

  17. In Vitro Effects of Hollow Gold Nanoshells on Human Aortic Endothelial Cells

    NASA Astrophysics Data System (ADS)

    Gu, Chunrong; Wu, Hengfang; Ge, Gaoyuan; Li, Xiongzhi; Guo, Zhirui; Bian, Zhiping; Xu, Jindan; Lu, Hua; Chen, Xiangjian; Yang, Di

    2016-09-01

    Gold nanoparticles are emerging as promising biomedical tools due to their unique nanoscale characteristics. Our purpose was to synthesize a hollow-shaped gold nanoparticle and to investigate its effect on human aortic endothelial cells (HAECs) in vitro. Hollow gold nanoshells with average 35-nm diameters and 10-nm shell thickness were obtained by galvanic replacement using quasi-spherical nanosilver as sacrifice-template. Our results showed that hollow gold nanoshells in the culture medium could be internalized into the cytoplasm of HAECs. No cytotoxicity effect of hollow gold nanoshells on HAECs was observed within the test concentrations (0-0.8 μg/mL) and test exposure period (0-72 h) by tetrazolium dye assay. Meanwhile, the release of cell injury biomarker, lactate dehydrogenase, was not significantly higher than that from control cells (without hollow gold nanoshells). The concentrations of vasodilators, nitric oxide, and prostacyclin I-2 were not changed, but the vasoconstrictor endothelin-1 was decreased by hollow gold nanoshells treatment in HAECs. HAECs exposed to hollow gold nanoshells resulted in suppressing expressions of genes involved in apoptosis and activating expressions of genes of adhesion molecules. Moreover, we demonstrated by in vitro endothelial tube formation that hollow gold nanoshells (0.8 μg/mL) could not inhibit angiogenesis by the HAECs. Altogether, these results indicate that the structure and major function of HAECs would not be disrupted by hollow gold nanoshell treatment.

  18. In Vitro Effects of Hollow Gold Nanoshells on Human Aortic Endothelial Cells.

    PubMed

    Gu, Chunrong; Wu, Hengfang; Ge, Gaoyuan; Li, Xiongzhi; Guo, Zhirui; Bian, Zhiping; Xu, Jindan; Lu, Hua; Chen, Xiangjian; Yang, Di

    2016-12-01

    Gold nanoparticles are emerging as promising biomedical tools due to their unique nanoscale characteristics. Our purpose was to synthesize a hollow-shaped gold nanoparticle and to investigate its effect on human aortic endothelial cells (HAECs) in vitro. Hollow gold nanoshells with average 35-nm diameters and 10-nm shell thickness were obtained by galvanic replacement using quasi-spherical nanosilver as sacrifice-template. Our results showed that hollow gold nanoshells in the culture medium could be internalized into the cytoplasm of HAECs. No cytotoxicity effect of hollow gold nanoshells on HAECs was observed within the test concentrations (0-0.8 μg/mL) and test exposure period (0-72 h) by tetrazolium dye assay. Meanwhile, the release of cell injury biomarker, lactate dehydrogenase, was not significantly higher than that from control cells (without hollow gold nanoshells). The concentrations of vasodilators, nitric oxide, and prostacyclin I-2 were not changed, but the vasoconstrictor endothelin-1 was decreased by hollow gold nanoshells treatment in HAECs. HAECs exposed to hollow gold nanoshells resulted in suppressing expressions of genes involved in apoptosis and activating expressions of genes of adhesion molecules. Moreover, we demonstrated by in vitro endothelial tube formation that hollow gold nanoshells (0.8 μg/mL) could not inhibit angiogenesis by the HAECs. Altogether, these results indicate that the structure and major function of HAECs would not be disrupted by hollow gold nanoshell treatment. PMID:27624340

  19. In Vitro Effects of Hollow Gold Nanoshells on Human Aortic Endothelial Cells.

    PubMed

    Gu, Chunrong; Wu, Hengfang; Ge, Gaoyuan; Li, Xiongzhi; Guo, Zhirui; Bian, Zhiping; Xu, Jindan; Lu, Hua; Chen, Xiangjian; Yang, Di

    2016-12-01

    Gold nanoparticles are emerging as promising biomedical tools due to their unique nanoscale characteristics. Our purpose was to synthesize a hollow-shaped gold nanoparticle and to investigate its effect on human aortic endothelial cells (HAECs) in vitro. Hollow gold nanoshells with average 35-nm diameters and 10-nm shell thickness were obtained by galvanic replacement using quasi-spherical nanosilver as sacrifice-template. Our results showed that hollow gold nanoshells in the culture medium could be internalized into the cytoplasm of HAECs. No cytotoxicity effect of hollow gold nanoshells on HAECs was observed within the test concentrations (0-0.8 μg/mL) and test exposure period (0-72 h) by tetrazolium dye assay. Meanwhile, the release of cell injury biomarker, lactate dehydrogenase, was not significantly higher than that from control cells (without hollow gold nanoshells). The concentrations of vasodilators, nitric oxide, and prostacyclin I-2 were not changed, but the vasoconstrictor endothelin-1 was decreased by hollow gold nanoshells treatment in HAECs. HAECs exposed to hollow gold nanoshells resulted in suppressing expressions of genes involved in apoptosis and activating expressions of genes of adhesion molecules. Moreover, we demonstrated by in vitro endothelial tube formation that hollow gold nanoshells (0.8 μg/mL) could not inhibit angiogenesis by the HAECs. Altogether, these results indicate that the structure and major function of HAECs would not be disrupted by hollow gold nanoshell treatment.

  20. Detection of water and its derivatives on individual nanoparticles using vibrational electron energy-loss spectroscopy.

    PubMed

    Crozier, Peter A; Aoki, Toshihiro; Liu, Qianlang

    2016-10-01

    Understanding the role of water, hydrate and hydroxyl species on nanoparticle surfaces and interfaces is very important in both physical and life sciences. Detecting the presence of oxygen-hydrogen species with nanometer resolution is extremely challenging at present. Here we show that the recently developed vibrational electron energy-loss spectroscopy using subnanometer focused electron beams can be employed to spectroscopically identify the local presence and variation of OH species on nanoscale surfaces. The hydrogen-oxygen fingerprint can be correlated with highly localized structural and morphological information obtained from electron imaging. Moreover, the current approach exploits the aloof beam mode of spectral acquisition which does not require direct electron irradiation of the sample thus greatly reducing beam damage to the OH bond. These findings open the door for using electron microscopy to probe local hydroxyl and hydrate species on nanoscale organic and inorganic structures. PMID:27423795

  1. The Smokey Hollow Community The Smokey Hollow Community, Informal ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    The Smokey Hollow Community - The Smokey Hollow Community, Informal boundaries by street name: North to South: East Jefferson Street to East Van Buren Street. West to East: South Gadsden Street to Marvin Street., Tallahassee, Leon County, FL

  2. Smokey Hollow Ethnographic Landscape Circa 1955 The Smokey Hollow ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Smokey Hollow Ethnographic Landscape Circa 1955 - The Smokey Hollow Community, Informal boundaries by street name: North to South: East Jefferson Street to East Van Buren Street. West to East: South Gadsden Street to Marvin Street., Tallahassee, Leon County, FL

  3. Impact of Engineered Zinc Oxide Nanoparticles on the Individual Performance of Mytilus galloprovincialis

    PubMed Central

    Hanna, Shannon K.; Miller, Robert J.; Muller, Erik B.; Nisbet, Roger M.; Lenihan, Hunter S.

    2013-01-01

    The increased use of engineered nanoparticles (ENPs) in consumer products raises the concern of environmental release and subsequent impacts in natural communities. We tested for physiological and demographic impacts of ZnO, a prevalent metal oxide ENP, on the mussel Mytilus galloprovincialis. We exposed mussels of two size classes, <4.5 and ≥4.5 cm shell length, to 0.1–2 mg l−1 ZnO ENPs in seawater for 12 wk, and measured the effect on mussel respiration, accumulation of Zn, growth, and survival. After 12 wk of exposure to ZnO ENPs, respiration rates of mussels increased with ZnO concentration. Mussels had up to three fold more Zn in tissues than control groups after 12 wk of exposure, but patterns of Zn accumulation varied with mussel size and Zn concentrations. Small mussels accumulated Zn 10 times faster than large mussels at 0.5 mg l−1, while large mussels accumulated Zn four times faster than small mussels at 2 mg l−1. Mussels exposed to 2 mg l−1 ZnO grew 40% less than mussels in our control group for both size classes. Survival significantly decreased only in groups exposed to the highest ZnO concentration (2 mg l−1) and was lower for small mussels than large. Our results indicate that ZnO ENPs are toxic to mussels but at levels unlikely to be reached in natural marine waters. PMID:23613941

  4. In situ Formation of a Monodispersed Spherical Mesoporous Nanosilica-Torlon Hollow-Fiber Composite for Carbon Dioxide Capture.

    PubMed

    Rownaghi, Ali A; Rezaei, Fateme; Labreche, Ying; Brennan, Patrick J; Johnson, Justin R; Li, Fuyue Stephanie; Koros, William J

    2015-10-26

    We describe a new template-free method for the in situ formation of a monodispersed spherical mesoporous nanosilica-Torlon hollow-fiber composite. A thin layer of Torlon hollow fiber that comprises silica nanoparticles was created by the in situ extrusion of a tetraethyl orthosilicate/N-methyl-2-pyrrolidone solution in a sheath layer and a Torlon polymer dope in a core support layer. This new method can be integrated easily into current hollow-fiber composite fabrication processes. The hollow-fiber composites were then functionalized with 3-aminopropyltrimethoxy silane (APS) and evaluated for their CO2 -capture performance. The resulting APS-functionalized mesoporous silica nanoparticles/Torlon hollow fibers exhibited a high CO2 equilibrium capacity of 1.5 and 1.9 mmol g(-1) at 35 and 60 °C, respectively, which is significantly higher than values for fiber sorbents without nanoparticles reported previously. PMID:26355795

  5. Hot hollow cathode gun assembly

    DOEpatents

    Zeren, J.D.

    1983-11-22

    A hot hollow cathode deposition gun assembly includes a hollow body having a cylindrical outer surface and an end plate for holding an adjustable heat sink, the hot hollow cathode gun, two magnets for steering the plasma from the gun into a crucible on the heat sink, and a shutter for selectively covering and uncovering the crucible.

  6. Hollow-Core Fiber Lamp

    NASA Technical Reports Server (NTRS)

    Yi, Lin (Inventor); Tjoelker, Robert L. (Inventor); Burt, Eric A. (Inventor); Huang, Shouhua (Inventor)

    2016-01-01

    Hollow-core capillary discharge lamps on the millimeter or sub-millimeter scale are provided. The hollow-core capillary discharge lamps achieve an increased light intensity ratio between 194 millimeters (useful) and 254 millimeters (useless) light than conventional lamps. The capillary discharge lamps may include a cone to increase light output. Hollow-core photonic crystal fiber (HCPCF) may also be used.

  7. Microfluidic generation of hollow Ca-alginate microfibers.

    PubMed

    Meng, Zhi-Jun; Wang, Wei; Xie, Rui; Ju, Xiao-Jie; Liu, Zhuang; Chu, Liang-Yin

    2016-07-01

    This work reports on an efficient microfluidic approach for continuous production of hollow Ca-alginate microfibers with controllable structures and functions. A coaxial microcapillary microfluidic device combined with a rotator is constructed to produce a cylindrical flow jet with four aqueous solutions as templates for continuous fabrication and collection of microfibers. A four-aqueous-phase flow jet with an intermediate buffer flow between the Ca(2+)-containing and alginate-containing flows is used as the template for microfiber fabrication. The buffer flow efficiently controls the diffusion of Ca(2+) into the alginate-containing flow as well as the crosslinking reaction, thus ensuring the continuous fabrication of hollow Ca-alginate microfibers under relatively low flow rates without clogging of the microchannel. The structure of the hollow microfibers can be flexibly adjusted by changing the flow rates and device dimensions. Meanwhile, the continuous fabrication process of the microfibers allows flexible incorporation of a functional component into the sheath flow for functionalization and addition of active substances in the core flow for encapsulation. This is demonstrated by fabricating hollow Ca-alginate microfibers with a wall containing magnetic nanoparticles for magnetic functionalization and with hollow internals containing Chlorella pyrenoidosa cells for confined growth. This work provides an efficient strategy for continuous fabrication of functional hollow Ca-alginate microfibers with controllable structures and functions.

  8. Microfluidic generation of hollow Ca-alginate microfibers.

    PubMed

    Meng, Zhi-Jun; Wang, Wei; Xie, Rui; Ju, Xiao-Jie; Liu, Zhuang; Chu, Liang-Yin

    2016-07-01

    This work reports on an efficient microfluidic approach for continuous production of hollow Ca-alginate microfibers with controllable structures and functions. A coaxial microcapillary microfluidic device combined with a rotator is constructed to produce a cylindrical flow jet with four aqueous solutions as templates for continuous fabrication and collection of microfibers. A four-aqueous-phase flow jet with an intermediate buffer flow between the Ca(2+)-containing and alginate-containing flows is used as the template for microfiber fabrication. The buffer flow efficiently controls the diffusion of Ca(2+) into the alginate-containing flow as well as the crosslinking reaction, thus ensuring the continuous fabrication of hollow Ca-alginate microfibers under relatively low flow rates without clogging of the microchannel. The structure of the hollow microfibers can be flexibly adjusted by changing the flow rates and device dimensions. Meanwhile, the continuous fabrication process of the microfibers allows flexible incorporation of a functional component into the sheath flow for functionalization and addition of active substances in the core flow for encapsulation. This is demonstrated by fabricating hollow Ca-alginate microfibers with a wall containing magnetic nanoparticles for magnetic functionalization and with hollow internals containing Chlorella pyrenoidosa cells for confined growth. This work provides an efficient strategy for continuous fabrication of functional hollow Ca-alginate microfibers with controllable structures and functions. PMID:27302737

  9. Hollow Mesoporous Plasmonic Nanoshells for Enhanced Solar Vapor Generation.

    PubMed

    Zielinski, Marcin S; Choi, Jae-Woo; La Grange, Thomas; Modestino, Miguel; Hashemi, Seyyed Mohammad Hosseini; Pu, Ye; Birkhold, Susanne; Hubbell, Jeffrey A; Psaltis, Demetri

    2016-04-13

    In the past decade, nanomaterials have made their way into a variety of technologies in solar energy, enhancing the performance by taking advantage of the phenomena inherent to the nanoscale. Recent examples exploit plasmonic core/shell nanoparticles to achieve efficient direct steam generation, showing great promise of such nanoparticles as a useful material for solar applications. In this paper, we demonstrate a novel technique for fabricating bimetallic hollow mesoporous plasmonic nanoshells that yield a higher solar vapor generation rate compared with their solid-core counterparts. On the basis of a combination of nanomasking and incomplete galvanic replacement, the hollow plasmonic nanoshells can be fabricated with tunable absorption and minimized scattering. When exposed to sun light, each hollow nanoshell generates vapor bubbles simultaneously from the interior and exterior. The vapor nucleating from the interior expands and diffuses through the pores and combines with the bubbles formed on the outer wall. The lack of a solid core significantly accelerates the initial vapor nucleation and the overall steam generation dynamics. More importantly, because the density of the hollow porous nanoshells is essentially equal to the surrounding host medium these particles are much less prone to sedimentation, a problem that greatly limits the performance and implementation of standard nanoparticle dispersions.

  10. Anionic ligand assisted synthesis of 3-D hollow TiO2 architecture with enhanced photoelectrochemical performance.

    PubMed

    Shin, Seong Sik; Kim, Dong Wook; Park, Jong Hoon; Kim, Dong Hoe; Kim, Ju Seong; Hong, Kug Sun; Cho, In Sun

    2014-12-30

    Hollow structured materials have shown great advantages for use in photoelectrochemical devices. However, their poor charge transport limits overall device performance. Here, we report a unique 3-D hollow architecture of TiO2 that greatly improves charge transport properties. We found that citric acid (CA) plays crucial roles in the formation of the 3-D hollow architecture. First, CA controls the hydrolysis rate of Ti ions and facilitates surface hydrolysis on templates during hydrothermal synthesis. Second, CA suppresses the growth of the carbon template at the initial reaction stage, resulting in the formation of comparatively small hollow fibers. More importantly, a prolonged hydrothermal reaction with CA enables a hollow sphere to grow into entangled hollow fibers via biomimetic swallowing growth. To demonstrate advantages of the 3-D hollow architecture for photoelectrochemical devices, we evaluated its photoelectrochemical performance, specifically the electrolyte diffusion and electron dynamics, by employing dye-sensitized solar cells as a model device. A systemic analysis reveals that the 3-D hollow architecture greatly improves both the electrolyte diffusion and electron transport compared to those of the nanoparticle and hollow sphere due to the elongated porous hollow morphology as well as the densely interconnected nanoparticles at the wall layer.

  11. 'Hank's Hollow' Sparkles

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This false-color composite panoramic camera image highlights mysterious and sparkly dust-like material that is created when the soil in this region is disturbed. NASA's Mars Exploration Rover Spirit took this image on sol 165 (June 20, 2004) in 'Hank's Hollow,' using filters L2, L5 and L7.

  12. Quantitative comparison of optimized nanorods, nanoshells and hollow nanospheres for photothermal therapy

    PubMed Central

    Kessentini, Sameh; Barchiesi, Dominique

    2012-01-01

    The purpose of this study is to get more efficient gold nanoparticles, for necrosis of cancer cells, in photothermal therapy. Therefore a numerical maximization of the absorption efficiency of a set of nanoparticles (nanorod, nanoshell and hollow nanosphere) is proposed, assuming that all the absorbed light is converted to heat. Two therapeutic cases (shallow and deep cancer) are considered. The numerical tools used in this study are the full Mie theory, the discrete dipole approximation and the particle swarm optimization. The optimization leads to an improved efficiency of the nanoparticles compared with previous studies. For the shallow cancer therapy, the hollow nanosphere seems to be more efficient than the other nanoparticles, whereas the hollow nanosphere and nanorod, offer comparable absorption efficiencies, for deep cancer therapy. Finally, a study of tolerance for the size parameters to guarantee an absorption efficiency threshold is included. PMID:22435104

  13. Mesoporous Silica Nanoparticle-Supported Lipid Bilayers (Protocells) for Active Targeting and Delivery to Individual Leukemia Cells.

    PubMed

    Durfee, Paul N; Lin, Yu-Shen; Dunphy, Darren R; Muñiz, Ayşe J; Butler, Kimberly S; Humphrey, Kevin R; Lokke, Amanda J; Agola, Jacob O; Chou, Stanley S; Chen, I-Ming; Wharton, Walker; Townson, Jason L; Willman, Cheryl L; Brinker, C Jeffrey

    2016-09-27

    Many nanocarrier cancer therapeutics currently under development, as well as those used in the clinical setting, rely upon the enhanced permeability and retention (EPR) effect to passively accumulate in the tumor microenvironment and kill cancer cells. In leukemia, where leukemogenic stem cells and their progeny circulate within the peripheral blood or bone marrow, the EPR effect may not be operative. Thus, for leukemia therapeutics, it is essential to target and bind individual circulating cells. Here, we investigate mesoporous silica nanoparticle (MSN)-supported lipid bilayers (protocells), an emerging class of nanocarriers, and establish the synthesis conditions and lipid bilayer composition needed to achieve highly monodisperse protocells that remain stable in complex media as assessed in vitro by dynamic light scattering and cryo-electron microscopy and ex ovo by direct imaging within a chick chorioallantoic membrane (CAM) model. We show that for vesicle fusion conditions where the lipid surface area exceeds the external surface area of the MSN and the ionic strength exceeds 20 mM, we form monosized protocells (polydispersity index <0.1) on MSN cores with varying size, shape, and pore size, whose conformal zwitterionic supported lipid bilayer confers excellent stability as judged by circulation in the CAM and minimal opsonization in vivo in a mouse model. Having established protocell formulations that are stable colloids, we further modified them with anti-EGFR antibodies as targeting agents and reverified their monodispersity and stability. Then, using intravital imaging in the CAM, we directly observed in real time the progression of selective targeting of individual leukemia cells (using the established REH leukemia cell line transduced with EGFR) and delivery of a model cargo. Overall, we have established the effectiveness of the protocell platform for individual cell targeting and delivery needed for leukemia and other disseminated disease. PMID:27419663

  14. Mesoporous Silica Nanoparticle-Supported Lipid Bilayers (Protocells) for Active Targeting and Delivery to Individual Leukemia Cells.

    PubMed

    Durfee, Paul N; Lin, Yu-Shen; Dunphy, Darren R; Muñiz, Ayşe J; Butler, Kimberly S; Humphrey, Kevin R; Lokke, Amanda J; Agola, Jacob O; Chou, Stanley S; Chen, I-Ming; Wharton, Walker; Townson, Jason L; Willman, Cheryl L; Brinker, C Jeffrey

    2016-09-27

    Many nanocarrier cancer therapeutics currently under development, as well as those used in the clinical setting, rely upon the enhanced permeability and retention (EPR) effect to passively accumulate in the tumor microenvironment and kill cancer cells. In leukemia, where leukemogenic stem cells and their progeny circulate within the peripheral blood or bone marrow, the EPR effect may not be operative. Thus, for leukemia therapeutics, it is essential to target and bind individual circulating cells. Here, we investigate mesoporous silica nanoparticle (MSN)-supported lipid bilayers (protocells), an emerging class of nanocarriers, and establish the synthesis conditions and lipid bilayer composition needed to achieve highly monodisperse protocells that remain stable in complex media as assessed in vitro by dynamic light scattering and cryo-electron microscopy and ex ovo by direct imaging within a chick chorioallantoic membrane (CAM) model. We show that for vesicle fusion conditions where the lipid surface area exceeds the external surface area of the MSN and the ionic strength exceeds 20 mM, we form monosized protocells (polydispersity index <0.1) on MSN cores with varying size, shape, and pore size, whose conformal zwitterionic supported lipid bilayer confers excellent stability as judged by circulation in the CAM and minimal opsonization in vivo in a mouse model. Having established protocell formulations that are stable colloids, we further modified them with anti-EGFR antibodies as targeting agents and reverified their monodispersity and stability. Then, using intravital imaging in the CAM, we directly observed in real time the progression of selective targeting of individual leukemia cells (using the established REH leukemia cell line transduced with EGFR) and delivery of a model cargo. Overall, we have established the effectiveness of the protocell platform for individual cell targeting and delivery needed for leukemia and other disseminated disease.

  15. Photocurrent enhancement of an individual gallium nitride nanowire decorated with gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Sundararajan, Jency Pricilla; Sargent, Meredith; McIlroy, David N.

    2011-03-01

    Variation in electron transport properties of individual n-type gallium nitride (GaN) nanowire and gold decorated gallium nitride (Au-GaN) nanowire were studied with respect to laser exposure of different wavelength and intensity. Single nanowire devices were manufactured by photolithography process in nanotechnology cleanroom, were characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM). A drop in electrical conductivity of Au-GaN nanowire was observed relative to bare GaN nanowire. Under laser illumination, we noticed an enhancement in photocurrent in Au-GaN nanowire, which increased with increase in excitation power at ambient conditions. We present a comparative study of the opto-electrical behavior of bare GaN nanowire vs Au-GaN nanowire and explain the IV characteristics and FET characteristics with respect to the length and diameter of nanowire. USDA, UI-BANTech.

  16. nanoparticles

    NASA Astrophysics Data System (ADS)

    Andreu-Cabedo, Patricia; Mondragon, Rosa; Hernandez, Leonor; Martinez-Cuenca, Raul; Cabedo, Luis; Julia, J. Enrique

    2014-10-01

    Thermal energy storage (TES) is extremely important in concentrated solar power (CSP) plants since it represents the main difference and advantage of CSP plants with respect to other renewable energy sources such as wind, photovoltaic, etc. CSP represents a low-carbon emission renewable source of energy, and TES allows CSP plants to have energy availability and dispatchability using available industrial technologies. Molten salts are used in CSP plants as a TES material because of their high operational temperature and stability of up to 500°C. Their main drawbacks are their relative poor thermal properties and energy storage density. A simple cost-effective way to improve thermal properties of fluids is to dope them with nanoparticles, thus obtaining the so-called salt-based nanofluids. In this work, solar salt used in CSP plants (60% NaNO3 + 40% KNO3) was doped with silica nanoparticles at different solid mass concentrations (from 0.5% to 2%). Specific heat was measured by means of differential scanning calorimetry (DSC). A maximum increase of 25.03% was found at an optimal concentration of 1 wt.% of nanoparticles. The size distribution of nanoparticle clusters present in the salt at each concentration was evaluated by means of scanning electron microscopy (SEM) and image processing, as well as by means of dynamic light scattering (DLS). The cluster size and the specific surface available depended on the solid content, and a relationship between the specific heat increment and the available particle surface area was obtained. It was proved that the mechanism involved in the specific heat increment is based on a surface phenomenon. Stability of samples was tested for several thermal cycles and thermogravimetric analysis at high temperature was carried out, the samples being stable.

  17. Parallel operation of miniature hollow cathode discharges

    SciTech Connect

    Schoenbach, K.H.; Peterkin, F.E.; Verhappen, R.

    1994-12-31

    The pressure where hollow cathode discharges operate scales inversely with the cathode hole diameter. By reducing the size of the cathode hole to less than one millimeter, the authors were able to obtain stable operation of the hollow cathode glow discharge in air, up to ten`s of torr. The current-voltage characteristic was found to have a positive slope below approximately 5 torr. This allows the authors to operate hollow cathode discharges in parallel at these pressures without using ballast resistors for the individual discharges. In an experiment with four 0.75 mm diameter cathode holes drilled in a 0.75 mm copper plate, the authors obtained stable operation of the discharges at a threshold voltage of 380 V and a total current of 0.16 mA. The intensity of the glow from each hole tended to equalize after several hours of operation. The system was run for approximately 40 hours without evident change in performance. The stability with respect to parallel operation offers the possibility to use miniature hollow cathode discharge arrays as flat panel electron and ion sources.

  18. HOLLOW CARBON ARC DISCHARGE

    DOEpatents

    Luce, J.S.

    1960-10-11

    A device is described for producing an energetic, direct current, hollow, carbon-arc discharge in an evacuated container and within a strong magnetic field. Such discharges are particularly useful not only in dissociation and ionization of high energy molecular ion beams, but also in acting as a shield or barrier against the instreaming of lowenergy neutral particles into a plasma formed within the hollow discharge when it is used as a dissociating mechanism for forming the plasma. There is maintained a predetermined ratio of gas particles to carbon particles released from the arc electrodes during operation of the discharge. The carbon particles absorb some of the gas particles and are pumped along and by the discharge out of the device, with the result that smaller diffusion pumps are required than would otherwise be necessary to dispose of the excess gas.

  19. Hollow spherical shell manufacture

    DOEpatents

    O'Holleran, T.P.

    1991-11-26

    A process is disclosed for making a hollow spherical shell of silicate glass composition in which an aqueous suspension of silicate glass particles and an immiscible liquid blowing agent is placed within the hollow spherical cavity of a porous mold. The mold is spun to reduce effective gravity to zero and to center the blowing agent, while being heated so as to vaporize the immiscible liquid and urge the water carrier of the aqueous suspension to migrate into the body of the mold, leaving a green shell compact deposited around the mold cavity. The green shell compact is then removed from the cavity, and is sintered for a time and a temperature sufficient to form a silicate glass shell of substantially homogeneous composition and uniform geometry. 3 figures.

  20. Hollow spherical shell manufacture

    DOEpatents

    O'Holleran, Thomas P.

    1991-01-01

    A process for making a hollow spherical shell of silicate glass composition in which an aqueous suspension of silicate glass particles and an immiscible liquid blowing agent is placed within the hollow spherical cavity of a porous mold. The mold is spun to reduce effective gravity to zero and to center the blowing agent, while being heated so as to vaporize the immiscible liquid and urge the water carrier of the aqueous suspension to migrate into the body of the mold, leaving a green shell compact deposited around the mold cavity. The green shell compact is then removed from the cavity, and is sintered for a time and a temperature sufficient to form a silicate glass shell of substantially homogeneous composition and uniform geometry.

  1. Synthesis of multi-shelled ZnO hollow microspheres and their improved photocatalytic activity

    PubMed Central

    2014-01-01

    Herein, we report an effective, facile, and low-cost route for preparing ZnO hollow microspheres with a controlled number of shells composed of small ZnO nanoparticles. The formation mechanism of multiple-shelled structures was investigated in detail. The number of shells is manipulated by using different diameters of carbonaceous microspheres. The products were characterized by X-ray powder diffraction, scanning electron microscopy, and transmission electron microscopy. The as-prepared ZnO hollow microspheres and ZnO nanoparticles were then used to study the degradation of methyl orange (MO) dye under ultraviolet (UV) light irradiation, and the triple-shelled ZnO hollow microspheres exhibit the best photocatalytic activity. This work is helpful to develop ZnO-based photocatalysts with high photocatalytic performance in addressing environmental protection issues, and it is also anticipated to other multiple-shelled metal oxide hollow microsphere structures. PMID:25328500

  2. Appropriate salt concentration of nanodiamond colloids for electrostatic self-assembly seeding of monosized individual diamond nanoparticles on silicon dioxide surfaces.

    PubMed

    Yoshikawa, Taro; Zuerbig, Verena; Gao, Fang; Hoffmann, René; Nebel, Christoph E; Ambacher, Oliver; Lebedev, Vadim

    2015-05-19

    Monosized (∼4 nm) diamond nanoparticles arranged on substrate surfaces are exciting candidates for single-photon sources and nucleation sites for ultrathin nanocrystalline diamond film growth. The most commonly used technique to obtain substrate-supported diamond nanoparticles is electrostatic self-assembly seeding using nanodiamond colloidal suspensions. Currently, monodisperse nanodiamond colloids, which have a narrow distribution of particle sizes centering on the core particle size (∼4 nm), are available for the seeding technique on different substrate materials such as Si, SiO2, Cu, and AlN. However, the self-assembled nanoparticles tend to form small (typically a few tens of nanometers or even larger) aggregates on all of those substrate materials. In this study, this major weakness of self-assembled diamond nanoparticles was solved by modifying the salt concentration of nanodiamond colloidal suspensions. Several salt concentrations of colloidal suspensions were prepared using potassium chloride as an inserted electrolyte and were examined with respect to seeding on SiO2 surfaces. The colloidal suspensions and the seeded surfaces were characterized by dynamic light scattering and atomic force microscopy, respectively. Also, the interaction energies between diamond nanoparticles in each of the examined colloidal suspensions were compared on the basis of the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. From these investigations, it became clear that the appropriate salt concentration suppresses the formation of small aggregates during the seeding process owing to the modified electrostatic repulsive interaction between nanoparticles. Finally, monosized (<10 nm) individual diamond nanoparticles arranged on SiO2 surfaces have been successfully obtained.

  3. Appropriate salt concentration of nanodiamond colloids for electrostatic self-assembly seeding of monosized individual diamond nanoparticles on silicon dioxide surfaces.

    PubMed

    Yoshikawa, Taro; Zuerbig, Verena; Gao, Fang; Hoffmann, René; Nebel, Christoph E; Ambacher, Oliver; Lebedev, Vadim

    2015-05-19

    Monosized (∼4 nm) diamond nanoparticles arranged on substrate surfaces are exciting candidates for single-photon sources and nucleation sites for ultrathin nanocrystalline diamond film growth. The most commonly used technique to obtain substrate-supported diamond nanoparticles is electrostatic self-assembly seeding using nanodiamond colloidal suspensions. Currently, monodisperse nanodiamond colloids, which have a narrow distribution of particle sizes centering on the core particle size (∼4 nm), are available for the seeding technique on different substrate materials such as Si, SiO2, Cu, and AlN. However, the self-assembled nanoparticles tend to form small (typically a few tens of nanometers or even larger) aggregates on all of those substrate materials. In this study, this major weakness of self-assembled diamond nanoparticles was solved by modifying the salt concentration of nanodiamond colloidal suspensions. Several salt concentrations of colloidal suspensions were prepared using potassium chloride as an inserted electrolyte and were examined with respect to seeding on SiO2 surfaces. The colloidal suspensions and the seeded surfaces were characterized by dynamic light scattering and atomic force microscopy, respectively. Also, the interaction energies between diamond nanoparticles in each of the examined colloidal suspensions were compared on the basis of the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. From these investigations, it became clear that the appropriate salt concentration suppresses the formation of small aggregates during the seeding process owing to the modified electrostatic repulsive interaction between nanoparticles. Finally, monosized (<10 nm) individual diamond nanoparticles arranged on SiO2 surfaces have been successfully obtained. PMID:25936368

  4. Liquid-gas boundary catalysis by using gold/polystyrene-coated hollow titania.

    PubMed

    Ran, Nur Hidayah Mohd; Yuliati, Leny; Lee, Siew Ling; Mahlia, Teuku Meurah Indra; Nur, Hadi

    2013-03-15

    A microparticle material of gold/polystyrene-coated hollow titania was successfully synthesized. The synthesis steps involved hydrothermal synthesis of a carbon sphere from sucrose as a template, coating of the carbon sphere with titania, removal of the carbon sphere to produce hollow titania, followed by coating of polystyrene on the surface of hollow titania and then attachment of gold nanoparticles. It has been demonstrated that this material can float on water due to its low density and it is a potential catalyst for liquid-gas boundary catalysis in oxidation of benzyl alcohol by using molecular oxygen.

  5. Liquid-gas boundary catalysis by using gold/polystyrene-coated hollow titania.

    PubMed

    Ran, Nur Hidayah Mohd; Yuliati, Leny; Lee, Siew Ling; Mahlia, Teuku Meurah Indra; Nur, Hadi

    2013-03-15

    A microparticle material of gold/polystyrene-coated hollow titania was successfully synthesized. The synthesis steps involved hydrothermal synthesis of a carbon sphere from sucrose as a template, coating of the carbon sphere with titania, removal of the carbon sphere to produce hollow titania, followed by coating of polystyrene on the surface of hollow titania and then attachment of gold nanoparticles. It has been demonstrated that this material can float on water due to its low density and it is a potential catalyst for liquid-gas boundary catalysis in oxidation of benzyl alcohol by using molecular oxygen. PMID:23380399

  6. A general route to hollow mesoporous rare-earth silicate nanospheres as a catalyst support.

    PubMed

    Jin, Renxi; Yang, Yang; Zou, Yongcun; Liu, Xianchun; Xing, Yan

    2014-02-17

    Hollow mesoporous structures have recently aroused intense research interest owing to their unique structural features. Herein, an effective and precisely controlled synthesis of hollow rare-earth silicate spheres with mesoporous shells is reported for the first time, produced by a simple hydrothermal method, using silica spheres as the silica precursors. The as-prepared hollow rare-earth silicate spheres have large specific surface area, high pore volume, and controllable structure parameters. The results demonstrate that the selection of the chelating reagent plays critical roles in forming the hollow mesoporous structures. In addition, a simple and low-energy-consuming approach to synthesize highly stable and dispersive gold nanoparticle-yttrium silicate (AuNPs/YSiO) hollow nanocomposites has also been developed. The reduction of 4-nitrophenol with AuNPs/YSiO hollow nanocomposites as the catalyst has clearly demonstrated that the hollow rare-earth silicate spheres are good carriers for Au nanoparticles. This strategy can be extended as a general approach to prepare multifunctional yolk-shell structures with diverse compositions and morphologies simply by replacing silica spheres with silica-coated nanocomposites.

  7. Double-shelled plasmonic Ag-TiO{sub 2} hollow spheres toward visible light-active photocatalytic conversion of CO{sub 2} into solar fuel

    SciTech Connect

    Feng, Shichao; Wang, Meng; Li, Ping; Tu, Wenguang; Zhou, Yong; Zou, Zhigang

    2015-10-01

    Double-shelled hollow hybrid spheres consisting of plasmonic Ag and TiO{sub 2} nanoparticles were successfully synthesized through a simple reaction process. The analysis reveals that Ag nanoparticles were dispersed uniformly in the TiO{sub 2} nanoparticle shell. The plasmonic Ag-TiO{sub 2} hollow sphere proves to greatly enhance the photocatalytic activity toward reduction of CO{sub 2} into renewable hydrocarbon fuel (CH{sub 4}) in the presence of water vapor under visible-light irradiation. The possible formation mechanism of the hollow sphere and related plasmon-enhanced photocatalytic performance were also briefly discussed.

  8. Visible Mie Scattering in Nonabsorbing Hollow Sphere Powders

    SciTech Connect

    M Retsch; M Schmelzeisen; H Butt; E Thomas

    2011-12-31

    Hollow silica nanoparticles (HSNP) with diameters comparable to visible wavelengths and with thin shells (<15 nm) feature an unexpected color effect. Single particle and powder spectroscopy, as well as calculations based on Mie theory were used to investigate this phenomenon. The use of HSNPs increases the transport mean free path of light significantly, which reduces multiple scattering, and thus the Mie resonances become visible to the bare eye.

  9. Preparation and Characterization of SnO2/Ag Hollow Microsphere via a Convenient Hydrothermal Route.

    PubMed

    Qiao, Xiuqing; Hu, Fuchao; Hou, Dongfang; Li, Dongsheng

    2016-04-01

    SnO2/Ag hollow microsphere, assembled form SnO2 and Ag nanoparticles, was synthesized via a facile one-step hydrothermal synthesis method using Na2SnO3.3H2O, CO(NH2)2 and AgNO3 as raw materials. XRD, SEM, and TEM results revealed that the obtained SnO2/Ag hollow microsphere with diameters of ca.3-5 µm was built from uniformly distributed rutile SnO2 and cubic Ag nanoparticles. Moreover, XPS results indicate the existence of strong interaction between Ag and SnO2 nanoparticles, rather than simply physical contact, endowing the SnO2/Ag hollow microspheres with excellent photocatalytic performance in the degradation of RhB solution under visible light irradiation. PMID:27451773

  10. Photoanode using hollow spherical TiO2 for duel functions in dye-sensitized solar cell.

    PubMed

    Ko, Hwan Ho; Yi, Sung; Jeong, Sung Hoon

    2013-12-01

    We report a new fabrication method of a bilayer photoanode for dye sensitized solar cell having highly crystalline TiO2 with hollow spherical nanoparticles. The hollow spherical TiO2 nanoparticles in DSSC work not only as scattering layer but also as channel of electrolyte. This is due to the fact that incident light is scattered by the hollow spherical nanoparticle according to Mie theory and spherical hollow spheres allow the empty space inside each sphere to circulate the electrolyte more effectively. The nanoparticles were synthesized by hydrothermal method. The space inside the spheres was fully developed by Ostwald Ripening process and the size of hollow spheres was controlled by concentration of PVPs and hydrothermal synthesis conditions (time and temperature). The nanoparticle size and photoanode morphology of the hollow spheres were measured by scanning electron microscope (SEM). Finally, the power conversion efficiency of 6.26% has been achieved under AM 1.5G simulated sunlights (100 mW cm(-2)). PMID:24266162

  11. Oriented-assembly of hollow FePt nanochains with tunable catalytic and magnetic properties

    NASA Astrophysics Data System (ADS)

    Liu, Jialong; Xia, Tianyu; Wang, Shouguo; Yang, Guang; Dong, Bowen; Wang, Chao; Ma, Qidi; Sun, Young; Wang, Rongming

    2016-06-01

    Hollow nanoparticles with large surface areas exhibit a lot of advantages for applications such as catalysis and energy storage. Furthermore, their performance can be manipulated by their deliberate assemblies. Dispersive hollow FePt nanospheres have been assembled into one-dimensional hollow FePt nanochains under the magnetic fields at room temperature. Based on the activation of galvanic replacement at different reaction stages, the size of hollow FePt nanochains can be deliberately manipulated varying from 20 nm to 300 nm, together with the length changing from 200 nm to 10 μm. The competition between movement of paramagnetic Fe3+ ions and shape recovering due to thermal fluctuations plays a critical effect on the structure of contact area between hollow nanospheres, leading to perforative structures. Compared with commercial Pt/C, well aligned hollow FePt nanochains show greatly enhanced catalytic activities in the methanol oxidation reaction (MOR) due to more favorable mass flow. Magnetic measurements indicate that the magnetic properties including Curie temperature and saturation magnetization can be tuned by the control of the size and shape of hollow nanochains.Hollow nanoparticles with large surface areas exhibit a lot of advantages for applications such as catalysis and energy storage. Furthermore, their performance can be manipulated by their deliberate assemblies. Dispersive hollow FePt nanospheres have been assembled into one-dimensional hollow FePt nanochains under the magnetic fields at room temperature. Based on the activation of galvanic replacement at different reaction stages, the size of hollow FePt nanochains can be deliberately manipulated varying from 20 nm to 300 nm, together with the length changing from 200 nm to 10 μm. The competition between movement of paramagnetic Fe3+ ions and shape recovering due to thermal fluctuations plays a critical effect on the structure of contact area between hollow nanospheres, leading to perforative

  12. Submicrometer-sized hierarchical hollow spheres of heavy lanthanide orthovanadates: sacrificial template synthesis, formation mechanism, and luminescent properties.

    PubMed

    Yang, Xiaoyan; Xu, Lin; Zhai, Zheng; Cheng, Fangfang; Yan, Zhenzhen; Feng, Xiaomiao; Zhu, Junjie; Hou, Wenhua

    2013-12-23

    Hollow spheres of heavy lanthanide orthovanadates (LnVO4, Ln = Tb, Dy, Er, Tm, Yb, Lu) and yolk-shell structures of Ho(OH)CO3@HoVO4 have been successfully prepared by employing Ln(OH)CO3 colloidal spheres as a sacrificial template and NH4VO3 as a vanadium source. In particular, the as-obtained LuVO4 hollow spheres are assembled from numerous hollow-structured elliptic nanoparticles, and their textural parameters such as the inner and outer diameters, shell thicknesses, and number of shells could be finely tuned through introducing different amounts of NH4VO3 and employing Lu(OH)CO3 templates with different sizes. The possible mechanisms for the formation of hollow spheres and yolk-shell structures, and also the hollow-structured elliptic nanoparticles of LuVO4, i.e., building blocks of LuVO4 hollow spheres, are proposed and discussed in detail. Under ultraviolet excitation, the obtained LuVO4:Eu(3+) hollow spheres show strong red emissions located in the saturated color region, and the modulation of emission intensity and color purity could be realized by tuning the textural parameters of the obtained hollow spheres. It was found that the nanostructure of the building blocks of LuVO4:Eu(3+) hollow spheres also had an effect on the luminescent properties of the as-obtained materials. Moreover, the quantum efficiency could be affected by the textural parameters of the as-obtained LuVO4:Eu(3+) hollow spheres, and the double-shelled LuVO4:Eu(3+) hollow sphere has the highest quantum efficiency. In addition, the excellent biocompatibility indicates the potential biological applications of LuVO4 hollow spheres.

  13. Mercury - the hollow planet

    NASA Astrophysics Data System (ADS)

    Rothery, D. A.

    2012-04-01

    Mercury is turning out to be a planet characterized by various kinds of endogenous hole (discounting impact craters), which are compared here. These include volcanic vents and collapse features on horizontal scales of tens of km, and smaller scale depressions ('hollows') associated with bright crater-floor deposits (BCFD). The BCFD hollows are tens of metres deep and kilometres or less across and are characteristically flat-floored, with steep, scalloped walls. Their form suggests that they most likely result from removal of surface material by some kind of mass-wasting process, probably associated with volume-loss caused by removal (via sublimation?) of a volatile component. These do not appear to be primarily a result of undermining. Determining the composition of the high-albedo bluish surface coating in BCFDs will be a key goal for BepiColombo instruments such as MIXS (Mercury Imaging Xray Spectrometer). In contrast, collapse features are non-circular rimless pits, typically on crater floors (pit-floor craters), whose morphology suggests collapse into void spaces left by magma withdrawal. This could be by drainage of either erupted lava (or impact melt) or of shallowly-intruded magma. Unlike the much smaller-scale BCFD hollows, these 'collapse pit' features tend to lack extensive flat floors and instead tend to be close to triangular in cross-section with inward slopes near to the critical angle of repose. The different scale and morphology of BCFD hollows and collapse pits argues for quite different modes of origin. However, BCFD hollows adjacent to and within the collapse pit inside Scarlatti crater suggest that the volatile material whose loss was responsible for the growth of the hollows may have been emplaced in association with the magma whose drainage caused the main collapse. Another kind of volcanic collapse can be seen within a 25 km-wide volcanic vent outside the southern rim of the Caloris basin (22.5° N, 146.1° E), on a 28 m/pixel MDIS NAC image

  14. Hollow-shelled nanoreactors endowed with high catalytic activity.

    PubMed

    Pérez-Lorenzo, Moisés; Vaz, Belén; Salgueiriño, Verónica; Correa-Duarte, Miguel A

    2013-09-01

    Hollow-shelled nanoreactors have emerged as efficient structures to maximize the potential of nanoparticles in the field of catalysis. In this Concept article, we underline the importance of both the morphology of the active nanoparticles as well as the composition and porosity of the shell for the catalytic performance of the overall nanocomposite. Different configurations are discussed, with a focus on preparative methods and applications in organic synthesis. Perspectives on future designs that may offer new opportunities to improve the selectivity of the catalyzed transformations and add additional features are also addressed, in order to illustrate the potential of these unique nanostructures.

  15. Hollow Polyimide Microspheres

    NASA Technical Reports Server (NTRS)

    Weiser, Erik S. (Inventor); St.Clair, Terry L. (Inventor); Echigo, Yoshiaki (Inventor); Kaneshiro, Hisayasu (Inventor)

    2001-01-01

    A shaped article composed of an aromatic polyimide has a hollow, essentially spherical structure and a particle size of about 100 to about 1500 micrometers, a density of about 1 to about 6 pounds/cubic foot and a volume change of 1 to about 20% by a pressure treatment of 30 psi for 10 minutes at room temperature. A syntactic foam, made of a multiplicity of the shaped articles which are bonded together by a matrix resin to form an integral composite structure, has a density of about 3 to about 30 pounds/cubic feet and a compression strength of about 100 to about 1400 pounds/sq inch.

  16. Hollow Polyimide Microspheres

    NASA Technical Reports Server (NTRS)

    Weiser, Erik S. (Inventor); St.Clair, Terry L. (Inventor); Echigo, Yoshiaki (Inventor); Kaneshiro, Hisayasu (Inventor)

    2000-01-01

    A shaped article composed of an aromatic polyimide has a hollow, essentially spherical structure and a particle size of about 100 to about 1500 microns a density of about 1 to about 6 pounds/cubic ft and a volume change of 1 to about 20 percent by a pressure treatment of 30 psi for 10 minutes at room temperature. A syntactic foam, made of a multiplicity of the shaped articles which are bonded together by a matrix resin to form an integral composite structure, has a density of about 3 to about 30 pounds/cubic ft and a compression strength 2 of about 100 to about 1400 pounds/sq in.

  17. Hollow Polyimide Microspheres

    NASA Technical Reports Server (NTRS)

    Weiser, Erik S. (Inventor); St.Clair, Terry L. (Inventor); Echigo, Yoshiaki (Inventor); Kaneshiro, Hisayasu (Inventor)

    1999-01-01

    A shaped article composed of an aromatic polyimide has a hollow, essentially spherical structure and a particle size of about 100 to about 1500 microns, a density of about I to about 6 pounds/ft3 and a volume change of 1 to about 20% by a pressure treatment of 30 psi for 10 minutes at room temperature. A syntactic foam, made of a multiplicity of the shaped articles which are bounded together by a matrix resin to form an integral composite structure, has a density of about 3 to about 30 pounds/cu ft and a compression strength of about 100 to about 1400 pounds/sq in.

  18. Uniform hollow magnetite spheres: Facile synthesis, growth mechanism, and their magnetic properties

    SciTech Connect

    Zhou, Xing; Zhao, Guizhe; Liu, Yaqing

    2014-11-15

    Highlights: • Uniform Fe{sub 3}O{sub 4} hollow spheres with high saturation magnetization were synthesized through a simple solvothermal process. • Without using any hard templates or external magnetic field. • The as-prepared magnetite hollow spheres exhibit a ferromagnetic behavior with high Ms of ca. 85.9 emu/g at room temperature. • The morphology of Fe{sub 3}O{sub 4} with nanoparticles, hollow, and irregular structures could be adjusted by changing the reactive conditions. - Abstract: Hierarchical porous Fe{sub 3}O{sub 4} hollow spheres with high saturation magnetization were synthesized through a simple solvothermal process in ethylene glycol (EG) in the presence of Tetrabutylammonium chloride (TBAC) and urea. By investigating the effect of reaction temperature, time, the amount of urea, and concentration of iron ion on the formation of hollow spheres, it was proposed that the main formation mechanism of hollow spheres is Ostwald ripening process combined with assembly-then-inside-out evacuation process. Additionally, it is found that the morphology of Fe{sub 3}O{sub 4} with nanoparticles, hollow, and irregular structures could be adjusted by changing the above factors. The resulting products were characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometer (VSM). The hierarchical porous Fe{sub 3}O{sub 4} hollow spheres exhibited enhanced saturation magnetization as compared with Fe{sub 3}O{sub 4} nanoparticles.

  19. Ultrasonic/surfactant assisted of CdS nano hollow sphere synthesis and characterization

    SciTech Connect

    Rafati, Amir Abbas; Borujeni, Ahmad Reza Afraz; Najafi, Mojgan; Bagheri, Ahmad

    2011-01-15

    CdS hollow nanospheres with diameters ranging from 40 to 150 nm have been synthesized by a surfactant-assisted sonochemical route. The successful vesicle templating indicates that the outer leaflet of the bilayer is the receptive surface in the controlled growth of CdS nanoparticles which provide the unique reactor for the nucleation and mineralization growth of CdS nanoparticles. The CdS nanostructures obtained were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet-visible spectroscopy and photoluminescence spectroscopy. Structural characterization of hollow CdS nanospheres indicates that these products packed with square subunits having sizes between 5 and 7 nm in diameter. The formation of the hollow nanostructure was explained by a vesicle template mechanism, in which sonication and surfactant play important roles. The band-edge emission and surface luminescence of the CdS nanoparticles were observed. -Research Highlights: {yields} CdS hollow nanospheres with diameters of 40-150 nm were synthesized. {yields} Nanoparticles were characterized by UV/Vis and photoluminescence. {yields} Nanospheres are composed of smaller nanocrystals with the average size of 6.8 nm. {yields} The band gap energy of the CdS nanoparticles is higher than its bulk value.

  20. Nickel sulfide hollow whisker formation

    SciTech Connect

    Holcomb, G.R.; Cramer, S.D.

    1997-02-01

    Hollow, high-aspect-ratio nickel sulfide whiskers were formed during aqueous corrosion experiments at 250 C by the US Department of Energy. The whiskers grew radially from Teflon thread at the waterline in acidic sodium sulfate solutions containing chloride additions. The hollow morphology is consistent with that reported for the mineral millerite found in nature in hematite cavities. The data suggest that iron and chloride impurities are necessary for the observed whisker structure. Hollow nickel sulfide whiskers were observed only in high-temperature corrosion experiments conducted on stainless steels; they were not observed in similar experiments on nickel-base alloys.

  1. 'Laguna Hollow'Undisturbed

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image shows the patch of soil at the bottom of the shallow depression dubbed 'Laguna Hollow' where the Mars Exploration Rover Spirit will soon begin trenching. Scientists are intrigued by the clustering of small pebbles and the crack-like fine lines, which indicate a coherent surface that expands and contracts. A number of processes can cause materials to expand and contract, including cycles of heating and cooling; freezing and thawing; and rising and falling of salty liquids within a substance. This false-color image was created using the blue, green and infrared filters of the rover's panoramic camera. Scientists chose this particular combination of filters to enhance the heterogeneity of the martian soil.

  2. Catalytic, hollow, refractory spheres

    NASA Technical Reports Server (NTRS)

    Wang, Taylor G. (Inventor); Elleman, Daniel D. (Inventor); Lee, Mark C. (Inventor); Kendall, Jr., James M. (Inventor)

    1987-01-01

    Improved, heterogeneous, refractory catalysts are in the form of gas-impervious, hollow, thin-walled spheres (10) suitable formed of a shell (12) of refractory such as alumina having a cavity (14) containing a gas at a pressure greater than atmospheric pressure. The wall material may be itself catalytic or a catalytically active material coated onto the sphere as a layer (16), suitably platinum or iron, which may be further coated with a layer (18) of activator or promoter. The density of the spheres (30) can be uniformly controlled to a preselected value within .+-.10 percent of the density of the fluid reactant such that the spheres either remain suspended or slowly fall or rise through the liquid reactant.

  3. Catalytic hollow spheres

    NASA Technical Reports Server (NTRS)

    Wang, Taylor G. (Inventor); Elleman, Daniel D. (Inventor); Lee, Mark C. (Inventor); Kendall, Jr., James M. (Inventor)

    1989-01-01

    The improved, heterogeneous catalysts are in the form of gas-impervious, hollow, thin-walled spheres (10) suitably formed of a shell (12) of metal such as aluminum having a cavity (14) containing a gas at a pressure greater than atmospheric pressure. The wall material may be, itself, catalytic or the catalyst can be coated onto the sphere as a layer (16), suitably platinum or iron, which may be further coated with a layer (18) of activator or promoter. The density of the spheres (30) can be uniformly controlled to a preselected value within .+-.10 percent of the density of the fluid reactant such that the spheres either remain suspended or slowly fall or rise through the liquid reactant.

  4. Synthesis and Characterization of Hollow TiO2 Particles Coated with Polyimide Brushes by Click Chemistry.

    PubMed

    Sun, Na; Zhao, Xiang; Xiao, Zhenggang

    2015-06-01

    In order to improve the compatibility between nanoparticles and polymer matrix, a feasible processing way for grafting polyimides (PI) on the surface of hollow TiO2 particles was developed. Hollow TiO2 spheres were prepared by using polystyrene-methyl acrylic acid latex as a template starting from tetrabutyl titanate. Surface graft of azide-decorated hollow TiO2 spheres with well-defined alkyne-terminated PI were achieved by "click" chemistry in three steps: (1) choloromethylation and azidization of hollow TiO2, (2) preparation of alkyne-terminated PI by polycondensation, (3) click coupling between the azidized hollow TiO2 and the alkyne-terminated PI under the catalysis of CuSO4/sodium ascorbate. Fourier transform infrared (FTIR) and Nuclear Magnetic Resonance (1HNMR) spectra were used to illustrate quantitative transformation of the PI brushes on hollow TiO2 particles into the desired functional group. The morphology of hollow TiO2-PI composite particles was characterized by transmission electron microscopy (TEM) which showed the irregular hollow structure. The results indicate that the grafting of polymer chains with thermostability and flame retardance on the surface of hollow TiO2 sphere is successful.

  5. Biotemplate synthesis of monodispersed iron phosphate hollow microspheres.

    PubMed

    Cao, Feng; Li, Dongxu

    2010-03-01

    Monodispersed iron phosphate hollow microspheres with a high degree of crystallization were prepared through a facile in situ deposition method using rape pollen grains as a biotemplate. The functional group on the surface of the pollen grains could adsorb Fe(3+), which provided the nucleation sites for growth of iron phosphate nanoparticles. After being sintered at 600 degrees C for 10 h, the pollen grains were removed and iron phosphate hollow microspheres were obtained. A scanning electron microscope and x-ray diffraction were applied to characterize the morphology and crystalline structure of the pollen grains, iron phosphate-coated pollen grains and iron phosphate hollow microspheres. Differential scanning calorimetry and thermogravity analyses were performed to investigate the thermal behavior of the iron phosphate-coated pollen grains during the calcinations. Energy dispersive spectroscopy and Fourier transform infrared spectroscopy were utilized to investigate the interaction between the pollen grains and iron phosphate. The effect of the pollen wall on the surface morphology of these iron phosphate hollow microspheres was also proven in this work.

  6. Method for sizing hollow microspheres

    DOEpatents

    Farnum, E.H.; Fries, R.J.

    1975-10-29

    Hollow Microspheres may be effectively sized by placing them beneath a screen stack completely immersed in an ultrasonic bath containing a liquid having a density at which the microspheres float and ultrasonically agitating the bath.

  7. Characterization of a radio frequency hollow electrode discharge at low gas pressures

    SciTech Connect

    Ahadi, Amir Mohammad; Rehders, Stefan; Strunskus, Thomas; Faupel, Franz; Trottenberg, Thomas; Kersten, Holger

    2015-08-15

    A radio frequency (RF) hollow discharge configuration is presented, which makes use of a combination of RF plasma generation and the hollow cathode effect. The system was especially designed for the treatment of nanoparticles, plasma polymerization, and nanocomposite fabrication. The process gas streams through the plasma in the inner of the cylindrical electrode system. In the here presented measurements, pure argon and argon with oxygen admixtures are exemplarily used. The discharge is characterized by probe measurements in the effluent, electrical measurements of the discharge parameters, and visual observations of the plasma glow. It is found that the RF fluctuations of the plasma potential are weak. The plasma potential resembles the one of a DC hollow cathode discharge, the RF hollow electrode acts as a cathode due to the self-bias, and a high voltage sheath forms in its inner cylinder.

  8. Characterization of a radio frequency hollow electrode discharge at low gas pressures

    NASA Astrophysics Data System (ADS)

    Ahadi, Amir Mohammad; Trottenberg, Thomas; Rehders, Stefan; Strunskus, Thomas; Kersten, Holger; Faupel, Franz

    2015-08-01

    A radio frequency (RF) hollow discharge configuration is presented, which makes use of a combination of RF plasma generation and the hollow cathode effect. The system was especially designed for the treatment of nanoparticles, plasma polymerization, and nanocomposite fabrication. The process gas streams through the plasma in the inner of the cylindrical electrode system. In the here presented measurements, pure argon and argon with oxygen admixtures are exemplarily used. The discharge is characterized by probe measurements in the effluent, electrical measurements of the discharge parameters, and visual observations of the plasma glow. It is found that the RF fluctuations of the plasma potential are weak. The plasma potential resembles the one of a DC hollow cathode discharge, the RF hollow electrode acts as a cathode due to the self-bias, and a high voltage sheath forms in its inner cylinder.

  9. Oriented-assembly of hollow FePt nanochains with tunable catalytic and magnetic properties.

    PubMed

    Liu, Jialong; Xia, Tianyu; Wang, Shouguo; Yang, Guang; Dong, Bowen; Wang, Chao; Ma, Qidi; Sun, Young; Wang, Rongming

    2016-06-01

    Hollow nanoparticles with large surface areas exhibit a lot of advantages for applications such as catalysis and energy storage. Furthermore, their performance can be manipulated by their deliberate assemblies. Dispersive hollow FePt nanospheres have been assembled into one-dimensional hollow FePt nanochains under the magnetic fields at room temperature. Based on the activation of galvanic replacement at different reaction stages, the size of hollow FePt nanochains can be deliberately manipulated varying from 20 nm to 300 nm, together with the length changing from 200 nm to 10 μm. The competition between movement of paramagnetic Fe(3+) ions and shape recovering due to thermal fluctuations plays a critical effect on the structure of contact area between hollow nanospheres, leading to perforative structures. Compared with commercial Pt/C, well aligned hollow FePt nanochains show greatly enhanced catalytic activities in the methanol oxidation reaction (MOR) due to more favorable mass flow. Magnetic measurements indicate that the magnetic properties including Curie temperature and saturation magnetization can be tuned by the control of the size and shape of hollow nanochains.

  10. Oriented-assembly of hollow FePt nanochains with tunable catalytic and magnetic properties.

    PubMed

    Liu, Jialong; Xia, Tianyu; Wang, Shouguo; Yang, Guang; Dong, Bowen; Wang, Chao; Ma, Qidi; Sun, Young; Wang, Rongming

    2016-06-01

    Hollow nanoparticles with large surface areas exhibit a lot of advantages for applications such as catalysis and energy storage. Furthermore, their performance can be manipulated by their deliberate assemblies. Dispersive hollow FePt nanospheres have been assembled into one-dimensional hollow FePt nanochains under the magnetic fields at room temperature. Based on the activation of galvanic replacement at different reaction stages, the size of hollow FePt nanochains can be deliberately manipulated varying from 20 nm to 300 nm, together with the length changing from 200 nm to 10 μm. The competition between movement of paramagnetic Fe(3+) ions and shape recovering due to thermal fluctuations plays a critical effect on the structure of contact area between hollow nanospheres, leading to perforative structures. Compared with commercial Pt/C, well aligned hollow FePt nanochains show greatly enhanced catalytic activities in the methanol oxidation reaction (MOR) due to more favorable mass flow. Magnetic measurements indicate that the magnetic properties including Curie temperature and saturation magnetization can be tuned by the control of the size and shape of hollow nanochains. PMID:26971675

  11. Mid-IR laser source using hollow waveguide beam combining

    NASA Astrophysics Data System (ADS)

    Elder, Ian F.; Thorne, Daniel H.; Lamb, Robert A.; Jenkins, R. M.

    2016-03-01

    Hollow waveguide technology is a route to efficient beam combining of multiple laser sources in a compact footprint. It is a technology appropriate for combining free-space or fibre-coupled beams generated by semiconductor, fibre or solidstate laser sources. This paper will present results of a breadboard mid-IR system comprising four laser sources combined using a hollow waveguide optical circuit. In this approach the individual dichroic beam combiner components are held in precision alignment slots in the hollow waveguide circuit and the different input wavelengths are guided between the components to a common output port. The hollow waveguide circuit is formed in the surface of a Macor (machinable glass-ceramic) substrate using precision CNC machining techniques. The hollow waveguides have fundamentally different propagation characteristics to solid core waveguides leading to transmission characteristics close to those of the atmosphere while still providing useful light guidance properties. The transmission efficiency and power handling of the hollow waveguide circuit can be designed to be very high across a broad waveband range. Three of the sources are quantum cascade lasers (QCLs), a semiconductor laser technology providing direct generation of midwave IR output. The combined beams provide 4.2 W of near diffraction-limited output co-boresighted to better than 20 µrad. High coupling efficiency into the waveguides is demonstrated, with negligible waveguide transmission losses. The overall transmission of the hollow waveguide beam combining optical circuit, weighted by the laser power at each wavelength, is 93%. This loss is dominated by the performance of the dichroic optics used to combine the beams.

  12. Hollow mesoporous raspberry-like colloids with removable caps as photoresponsive nanocontainers.

    PubMed

    Hu, Chi; West, Kevin R; Scherman, Oren A

    2016-04-21

    The fabrication, characterisation and controlled cargo release of hollow mesoporous raspberry-like colloids (HMRCs), which are assembled by utilising host-guest complexation of cucurbit[8]uril (CB[8]) are described. CB[8] is employed as a supramolecular linker to 'stick' the viologen functionalised paramagnetic iron oxide nanoparticles onto an azobenzene functionalised hollow mesoporous silica core. The formed HMRCs are photoresponsive and can be reversibly disassembled upon light irradiation, endowing them with an ability to release loaded cargo under photocontrol. While the assembled HMRCs retain cargo inside their cavity, disassembled particles with their iron oxide nanoparticle 'caps' removed will release the loaded cargo through the mesoporous shell of the hollow silica colloids. A model system using a boronic acid derivative as the cargo in the HMRCs and Alizarin Red salt as a sensor for the released boronic acid is demonstrated. PMID:27010833

  13. Hollow mesoporous raspberry-like colloids with removable caps as photoresponsive nanocontainers.

    PubMed

    Hu, Chi; West, Kevin R; Scherman, Oren A

    2016-04-21

    The fabrication, characterisation and controlled cargo release of hollow mesoporous raspberry-like colloids (HMRCs), which are assembled by utilising host-guest complexation of cucurbit[8]uril (CB[8]) are described. CB[8] is employed as a supramolecular linker to 'stick' the viologen functionalised paramagnetic iron oxide nanoparticles onto an azobenzene functionalised hollow mesoporous silica core. The formed HMRCs are photoresponsive and can be reversibly disassembled upon light irradiation, endowing them with an ability to release loaded cargo under photocontrol. While the assembled HMRCs retain cargo inside their cavity, disassembled particles with their iron oxide nanoparticle 'caps' removed will release the loaded cargo through the mesoporous shell of the hollow silica colloids. A model system using a boronic acid derivative as the cargo in the HMRCs and Alizarin Red salt as a sensor for the released boronic acid is demonstrated.

  14. Hollow mesoporous raspberry-like colloids with removable caps as photoresponsive nanocontainers

    NASA Astrophysics Data System (ADS)

    Hu, Chi; West, Kevin R.; Scherman, Oren A.

    2016-04-01

    The fabrication, characterisation and controlled cargo release of hollow mesoporous raspberry-like colloids (HMRCs), which are assembled by utilising host-guest complexation of cucurbit[8]uril (CB[8]) are described. CB[8] is employed as a supramolecular linker to `stick' the viologen functionalised paramagnetic iron oxide nanoparticles onto an azobenzene functionalised hollow mesoporous silica core. The formed HMRCs are photoresponsive and can be reversibly disassembled upon light irradiation, endowing them with an ability to release loaded cargo under photocontrol. While the assembled HMRCs retain cargo inside their cavity, disassembled particles with their iron oxide nanoparticle `caps' removed will release the loaded cargo through the mesoporous shell of the hollow silica colloids. A model system using a boronic acid derivative as the cargo in the HMRCs and Alizarin Red salt as a sensor for the released boronic acid is demonstrated.The fabrication, characterisation and controlled cargo release of hollow mesoporous raspberry-like colloids (HMRCs), which are assembled by utilising host-guest complexation of cucurbit[8]uril (CB[8]) are described. CB[8] is employed as a supramolecular linker to `stick' the viologen functionalised paramagnetic iron oxide nanoparticles onto an azobenzene functionalised hollow mesoporous silica core. The formed HMRCs are photoresponsive and can be reversibly disassembled upon light irradiation, endowing them with an ability to release loaded cargo under photocontrol. While the assembled HMRCs retain cargo inside their cavity, disassembled particles with their iron oxide nanoparticle `caps' removed will release the loaded cargo through the mesoporous shell of the hollow silica colloids. A model system using a boronic acid derivative as the cargo in the HMRCs and Alizarin Red salt as a sensor for the released boronic acid is demonstrated. Electronic supplementary information (ESI) available. See DOI: 10.1039/C6NR01016D

  15. Silicon core-hollow carbon shell nanocomposites with tunable buffer voids for high capacity anodes of lithium-ion batteries.

    PubMed

    Chen, Shuru; Gordin, Mikhail L; Yi, Ran; Howlett, Giles; Sohn, Hiesang; Wang, Donghai

    2012-10-01

    Silicon core-hollow carbon shell nanocomposites with controllable voids between silicon nanoparticles and hollow carbon shell were easily synthesized by a two-step coating method and exhibited different charge-discharge cyclability as anodes for lithium-ion batteries. The best capacity retention can be achieved with a void/Si volume ratio of approx. 3 due to its appropriate volume change tolerance and maintenance of good electrical contacts.

  16. Microemulsion-based synthesis of nanoscaled silver hollow spheres and direct comparison with massive particles of similar size

    NASA Astrophysics Data System (ADS)

    Kind, Christian; Popescu, Radian; Müller, Erich; Gerthsen, Dagmar; Feldmann, Claus

    2010-10-01

    Nanoscale silver hollow spheres are first prepared via a microemulsion approach with 15-20 nm as the outer diameter, 3-5 nm as the wall thickness, and 10-15 nm as the diameter of the inner cavity. The presence of hollow spheres is confirmed by electron microscopy (SEM, BF-/HAADF-STEM, HRTEM) as well as by X-ray diffraction with a line-shape analysis to characterize the microcrystalline properties. In addition to the hollow spheres, massive silver nanoparticles of similar size (outer diameter of 15-20 nm) are gained via microemulsions. Based on the similarity of experimental conditions and the resulting particle size, as-prepared silver hollow spheres and massive nanoparticles are used to compare their optical properties and surface-plasmon resonance. In contrast to reducing the diameter of massive particles, ``hollowing'' of silver nanoparticles leads to a red-shift of the plasmon resonance. With a red shift of about 33 nm in the case of the hollow spheres, a quantum-size effect is indeed observed and in accordance with the thin sphere wall.

  17. Microemulsion-based synthesis of nanoscaled silver hollow spheres and direct comparison with massive particles of similar size.

    PubMed

    Kind, Christian; Popescu, Radian; Müller, Erich; Gerthsen, Dagmar; Feldmann, Claus

    2010-10-01

    Nanoscale silver hollow spheres are first prepared via a microemulsion approach with 15-20 nm as the outer diameter, 3-5 nm as the wall thickness, and 10-15 nm as the diameter of the inner cavity. The presence of hollow spheres is confirmed by electron microscopy (SEM, BF-/HAADF-STEM, HRTEM) as well as by X-ray diffraction with a line-shape analysis to characterize the microcrystalline properties. In addition to the hollow spheres, massive silver nanoparticles of similar size (outer diameter of 15-20 nm) are gained via microemulsions. Based on the similarity of experimental conditions and the resulting particle size, as-prepared silver hollow spheres and massive nanoparticles are used to compare their optical properties and surface-plasmon resonance. In contrast to reducing the diameter of massive particles, "hollowing" of silver nanoparticles leads to a red-shift of the plasmon resonance. With a red shift of about 33 nm in the case of the hollow spheres, a quantum-size effect is indeed observed and in accordance with the thin sphere wall. PMID:20694210

  18. Self-templated formation of uniform NiCo2O4 hollow spheres with complex interior structures for lithium-ion batteries and supercapacitors.

    PubMed

    Shen, Laifa; Yu, Le; Yu, Xin-Yao; Zhang, Xiaogang; Lou, Xiong Wen David

    2015-02-01

    Despite the significant advancement in preparing metal oxide hollow structures, most approaches rely on template-based multistep procedures for tailoring the interior structure. In this work, we develop a new generally applicable strategy toward the synthesis of mixed-metal-oxide complex hollow spheres. Starting with metal glycerate solid spheres, we show that subsequent thermal annealing in air leads to the formation of complex hollow spheres of the resulting metal oxide. We demonstrate the concept by synthesizing highly uniform NiCo2O4 hollow spheres with a complex interior structure. With the small primary building nanoparticles, high structural integrity, complex interior architectures, and enlarged surface area, these unique NiCo2O4 hollow spheres exhibit superior electrochemical performances as advanced electrode materials for both lithium-ion batteries and supercapacitors. This approach can be an efficient self-templated strategy for the preparation of mixed-metal-oxide hollow spheres with complex interior structures and functionalities.

  19. Well-defined hollow nanochanneled-silica nanospheres prepared with the aid of sacrificial copolymer nanospheres and surfactant nanocylinders

    NASA Astrophysics Data System (ADS)

    Kim, Young Yong; Hwang, Bora; Song, Sungjin; Ree, Brian J.; Kim, Yongjin; Cho, Seo Yeon; Heo, Kyuyoung; Kwon, Yong Ku; Ree, Moonhor

    2015-08-01

    A new approach for synthesizing well-defined hollow nanochanneled-silica nanosphere particles is demonstrated, and the structural details of these particles are described for the first time. Positively charged styrene copolymer nanospheres with a clean, smooth surface and a very narrow size distribution are synthesized by surfactant-free emulsion copolymerization and used as a thermal sacrificial core template for the production of core-shell nanoparticles. A surfactant/silica composite shell with a uniform thickness is successfully produced and deposited onto the polymeric core template by charge density matching between the polymer nanosphere template surface and the negatively charged silica precursors and then followed by selective thermal decomposition of the polymeric core and the surfactant cylinder domains in the shell, producing the hollow nanochanneled-silica nanospheres. Comprehensive, quantitative structural analyses collectively confirm that the obtained nanoparticles are structurally well defined with a hollow core and a shell composed of cylindrical nanochannels that provide facile accessibility to the hollow interior space. Overall, the hollow nanochanneled-silica nanoparticles have great potential for applications in various fields.A new approach for synthesizing well-defined hollow nanochanneled-silica nanosphere particles is demonstrated, and the structural details of these particles are described for the first time. Positively charged styrene copolymer nanospheres with a clean, smooth surface and a very narrow size distribution are synthesized by surfactant-free emulsion copolymerization and used as a thermal sacrificial core template for the production of core-shell nanoparticles. A surfactant/silica composite shell with a uniform thickness is successfully produced and deposited onto the polymeric core template by charge density matching between the polymer nanosphere template surface and the negatively charged silica precursors and then

  20. Fabrication of hollow ZnO particles and its photocatalytic property by modifying of nano ZnS.

    PubMed

    Song, Ge; Li, Wenjiang

    2013-02-01

    Large scale hollow ZnO spheres were prepared by a solvothermal method with the help of the solvent. And ZnS nanoparticles were successfully fabricated on the surface of ZnO via a hydrothermal process. These heterostructured ZnO/ZnS core/shell particles are around 1-2 microm in diameter, the ZnS shell formed on the surface of hollow ZnO sphere is comprise of the primary crystals about 30 nm in diameter. The products prepared were characterized by field emission scanning electron microscope (FE-SEM), X-ray powder diffraction (XRD), transmission electron microscope (TEM), and photo-luminescence spectroscope (PL). Theoretical calculation and experimental results have demonstrated that the combination of ZnO and ZnS (two wide band gap semiconductors) could yield a novel material with the photoexcitation threshold energy lower than the individual components. The electron transfers between ZnO core and ZnS shell, which strongly affect the photoluminescence and photocatalytic performances. The photocatalytic activities of the products were evaluated by methyl orange degradation as a probe reaction. The relationship of ZnO/ZnS core/shell particles as excellent photocatalyst could be anticipated.

  1. Shape-tunable hollow silica nanomaterials based on a soft-templating method and their application as a drug carrier.

    PubMed

    Chen, Jiao; Wu, Xu; Hou, Xiaodong; Su, Xingguang; Chu, Qianli; Fahruddin, Nenny; Zhao, Julia Xiaojun

    2014-12-24

    A one-step soft-templating method for synthesizing shape-tunable hollow silica nanomaterials was developed in a reliable and highly reproducible way. For the first time, both nonspherical and spherical shapes with hollow interiors, including nanowire, nanospheres, and nanotadpole, were successfully obtained by simply changing the solvent. Poly(vinylpyrrolidone) (PVP)-water droplets were used as soft templates for the formation of hollow structures, while three different solvents, including 1-propanol, 1-pentanol, and ethanol, led to the designed shapes. It was found that the solvent, the formation of PVP-water droplets, the amount of ammonia, and the reaction time had great effects on the morphology of synthesized hollow nanomaterials. The effect of various factors on the morphology was systematically studied to propose a growth mechanism. The obtained hollow silica nanomaterials showed excellent reproducibility and great potential for a large-scale synthesis. Finally, the application of the developed hollow silica nanomaterials was demonstrated using the hollow spherical silica nanoparticles. Its drug-carrying ability was studied. The results could be extended for doping various target molecules into the hollow structures for a broad range of applications.

  2. Hollow sphere ceramic particles for abradable coatings

    SciTech Connect

    Longo, F.N.; Bader, N.F. III; Dorfman, M.R.

    1984-05-22

    A hollow sphere ceramic flame spray powder is disclosed. The desired constituents are first formed into agglomerated particles in a spray drier. Then the agglomerated particles are introduced into a plasma flame which is adjusted so that the particles collected are substantially hollow. The hollow sphere ceramic particles are suitable for flame spraying a porous and abradable coating. The hollow particles may be selected from the group consisting of zirconium oxide and magnesium zirconate.

  3. New route for hollow materials

    PubMed Central

    Rivaldo-Gómez, C. M.; Ferreira, F. F.; Landi, G. T.; Souza, J. A.

    2016-01-01

    Hollow micro/nano structures form an important family of functional materials. We have used the thermal oxidation process combined with the passage of electric current during a structural phase transition to disclose a colossal mass diffusion transfer of Ti ions. This combination points to a new route for fabrication of hollow materials. A structural phase transition at high temperature prepares the stage by giving mobility to Ti ions and releasing vacancies to the system. The electric current then drives an inward delocalization of vacancies, condensing into voids, and finally turning into a big hollow. This strong physical phenomenon leading to a colossal mass transfer through ionic diffusion is suggested to be driven by a combination of phase transition and electrical current followed by chemical reaction. We show this phenomenon for Ti leading to TiO2 microtube formation, but we believe that it can be used to other metals undergoing structural phase transition at high temperatures. PMID:27554448

  4. New route for hollow materials.

    PubMed

    Rivaldo-Gómez, C M; Ferreira, F F; Landi, G T; Souza, J A

    2016-01-01

    Hollow micro/nano structures form an important family of functional materials. We have used the thermal oxidation process combined with the passage of electric current during a structural phase transition to disclose a colossal mass diffusion transfer of Ti ions. This combination points to a new route for fabrication of hollow materials. A structural phase transition at high temperature prepares the stage by giving mobility to Ti ions and releasing vacancies to the system. The electric current then drives an inward delocalization of vacancies, condensing into voids, and finally turning into a big hollow. This strong physical phenomenon leading to a colossal mass transfer through ionic diffusion is suggested to be driven by a combination of phase transition and electrical current followed by chemical reaction. We show this phenomenon for Ti leading to TiO2 microtube formation, but we believe that it can be used to other metals undergoing structural phase transition at high temperatures. PMID:27554448

  5. New route for hollow materials

    NASA Astrophysics Data System (ADS)

    Rivaldo-Gómez, C. M.; Ferreira, F. F.; Landi, G. T.; Souza, J. A.

    2016-08-01

    Hollow micro/nano structures form an important family of functional materials. We have used the thermal oxidation process combined with the passage of electric current during a structural phase transition to disclose a colossal mass diffusion transfer of Ti ions. This combination points to a new route for fabrication of hollow materials. A structural phase transition at high temperature prepares the stage by giving mobility to Ti ions and releasing vacancies to the system. The electric current then drives an inward delocalization of vacancies, condensing into voids, and finally turning into a big hollow. This strong physical phenomenon leading to a colossal mass transfer through ionic diffusion is suggested to be driven by a combination of phase transition and electrical current followed by chemical reaction. We show this phenomenon for Ti leading to TiO2 microtube formation, but we believe that it can be used to other metals undergoing structural phase transition at high temperatures.

  6. Efficient Photocatalytic Activities of TiO2 Hollow Fibers with Mixed Phases and Mesoporous Walls.

    PubMed

    Hou, Huilin; Shang, Minghui; Wang, Lin; Li, Wenge; Tang, Bin; Yang, Weiyou

    2015-01-01

    Currently, Degussa P25, with the typical mixed phases of anatase and rutile TiO2, is widely applied as the commercial photocatalysts. However, there are still some of obstacles for the P25 nanoparticles with totally high photocatalytic activities, especially for the catalytic stability due to their inevitable aggregation of the nanoparticles when used as the photocatalysts. In the present work, we reported the exploration of a novel TiO2 photocatalyst, which could offer an ideal platform for synergetic combination of the mixed-phase composition, hollow architecture and mesoporous walls for the desired excellent photocatalytic efficiency and robust stability. The mesoporous TiO2 hollow nanofibers were fabricated via a facile single capillary electrospinning technique, in which the foaming agents were used for creating mesopores throughout the walls of the hollow fibers. The obtained hollow fibers exhibit a high purity and possess the mixed phases of 94.6% anatase and 5.4% rutile TiO2. As compared to P25, the as-fabricated mesoporous TiO2 hollow fibers exhibited much higher efficient photocatalytic activities and stabilities toward the hydrogen evolution with a rate of ~499.1 μmol g(-1)·h(-1) and ~99.5% degradation Rhodamine B (RhB) in 60 min, suggesting their promising application in efficient photocatalysts. PMID:26470013

  7. Efficient Photocatalytic Activities of TiO2 Hollow Fibers with Mixed Phases and Mesoporous Walls

    PubMed Central

    Hou, Huilin; Shang, Minghui; Wang, Lin; Li, Wenge; Tang, Bin; Yang, Weiyou

    2015-01-01

    Currently, Degussa P25, with the typical mixed phases of anatase and rutile TiO2, is widely applied as the commercial photocatalysts. However, there are still some of obstacles for the P25 nanoparticles with totally high photocatalytic activities, especially for the catalytic stability due to their inevitable aggregation of the nanoparticles when used as the photocatalysts. In the present work, we reported the exploration of a novel TiO2 photocatalyst, which could offer an ideal platform for synergetic combination of the mixed-phase composition, hollow architecture and mesoporous walls for the desired excellent photocatalytic efficiency and robust stability. The mesoporous TiO2 hollow nanofibers were fabricated via a facile single capillary electrospinning technique, in which the foaming agents were used for creating mesopores throughout the walls of the hollow fibers. The obtained hollow fibers exhibit a high purity and possess the mixed phases of 94.6% anatase and 5.4% rutile TiO2. As compared to P25, the as-fabricated mesoporous TiO2 hollow fibers exhibited much higher efficient photocatalytic activities and stabilities toward the hydrogen evolution with a rate of ~499.1 μmol g−1·h−1 and ~99.5% degradation Rhodamine B (RhB) in 60 min, suggesting their promising application in efficient photocatalysts. PMID:26470013

  8. Efficient Photocatalytic Activities of TiO2 Hollow Fibers with Mixed Phases and Mesoporous Walls

    NASA Astrophysics Data System (ADS)

    Hou, Huilin; Shang, Minghui; Wang, Lin; Li, Wenge; Tang, Bin; Yang, Weiyou

    2015-10-01

    Currently, Degussa P25, with the typical mixed phases of anatase and rutile TiO2, is widely applied as the commercial photocatalysts. However, there are still some of obstacles for the P25 nanoparticles with totally high photocatalytic activities, especially for the catalytic stability due to their inevitable aggregation of the nanoparticles when used as the photocatalysts. In the present work, we reported the exploration of a novel TiO2 photocatalyst, which could offer an ideal platform for synergetic combination of the mixed-phase composition, hollow architecture and mesoporous walls for the desired excellent photocatalytic efficiency and robust stability. The mesoporous TiO2 hollow nanofibers were fabricated via a facile single capillary electrospinning technique, in which the foaming agents were used for creating mesopores throughout the walls of the hollow fibers. The obtained hollow fibers exhibit a high purity and possess the mixed phases of 94.6% anatase and 5.4% rutile TiO2. As compared to P25, the as-fabricated mesoporous TiO2 hollow fibers exhibited much higher efficient photocatalytic activities and stabilities toward the hydrogen evolution with a rate of ~499.1 μmol g-1·h-1 and ~99.5% degradation Rhodamine B (RhB) in 60 min, suggesting their promising application in efficient photocatalysts.

  9. High pressure hollow electrode discharges

    SciTech Connect

    Schoenbach, K.H.; El-Habachi, A.; Shi, W.; Ciocca, M.

    1997-12-31

    Reduction of the cathode hole diameter into the submillimeter range has allowed the authors to extend the pressure range for hollow electrode discharge operation to values on the order of 50 Torr. In recent experiments with cathode holes of 0.2 mm diameter they obtained stable glow discharge operation up to approximately 900 Torr in argon. The current-voltage (I-V) characteristics of these discharges (with currents ranging from the ten`s of {micro}A to ten mA) show three distinct discharge modes: at low current, a discharge with positive differential resistivity, followed by a range with strong increase in current and reduction in voltage, and, at high current, again a resistive discharge mode. For low pressure (< 100 Torr) these modes correspond to the predischarge, hollow cathode discharge (sustained by pendulum electrons), and abnormal glow discharge, respectively. At higher pressure the discharge in the short gap system (anode-cathode distance: 0.25 mm) changes from a hollow cathode discharge to, what seems to be a pulseless partial glow discharge. In hollow cathode discharges operated in the torr range the electron energy distribution is known to be strongly non-maxwellian with a large concentration of electrons at energies greater than 30 eV. This holds also for hollow cathode discharge at high pressure and for partial discharges as indicated by the presence of strong excimer lines in the VUV spectrum of Ar-discharges at 128 nm and Xe-discharges at 172 nm. The resistive characteristic of high pressure hollow electrode discharges over a large range of current allows them to generate arrays of these discharges for use as flat panel, direct current, excimer lamps.

  10. Ion-exchange hollow fibers

    NASA Technical Reports Server (NTRS)

    Rembaum, A.; Yen, S. P. S.; Klein, E. (Inventor)

    1976-01-01

    An ion-exchange hollow fiber is prepared by introducing into the wall of the fiber polymerizable liquid monomers, and polymerizing the monomers therein to form solid, insoluble, crosslinked, ion-exchange resin particles which embed in the wall of the fiber. Excess particles blocking the central passage or bore of the fiber are removed by forcing liquid through the fiber. The fibers have high ion-exchange capacity, a practical wall permeability and good mechanical strength even with very thin wall dimensions. Experimental investigation of bundles of ion-exchange hollow fibers attached to a header assembly have shown the fiber to be very efficient in removing counterions from solution.

  11. Quartz antenna with hollow conductor

    DOEpatents

    Leung, Ka-Ngo; Benabou, Elie

    2002-01-01

    A radio frequency (RF) antenna for plasma ion sources is formed of a hollow metal conductor tube disposed within a glass tube. The hollow metal tubular conductor has an internal flow channel so that there will be no coolant leakage if the outer glass tube of the antenna breaks. A portion of the RF antenna is formed into a coil; the antenna is used for inductively coupling RF power to a plasma in an ion source chamber. The antenna is made by first inserting the metal tube inside the glass tube, and then forming the glass/metal composite tube into the desired coil shape.

  12. Ion-exchange hollow fibers

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Yen, Shiao-Ping S. (Inventor); Klein, Elias (Inventor)

    1980-01-01

    An ion-exchange hollow fiber is prepared by introducing into the wall of the fiber polymerizable liquid monomers, and polymerizing the monomers therein to form solid, insoluble, cross-linked, ion-exchange resin particles which embed in the wall of the fiber. Excess particles blocking the central passage or bore of the fiber are removed by forcing liquid through the fiber. The fibers have high ion-exchange capacity, a practical wall permeability and good mechanical strength even with very thin wall dimensions. Experimental investigation of bundles of ion-exchange hollow fibers attached to a header assembly have shown the fiber to be very efficient in removing counterions from solution.

  13. Ion-exchange hollow fibers

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Yen, Shiao-Ping S. (Inventor); Klein, Elias (Inventor)

    1977-01-01

    An ion-exchange hollow fiber is prepared by introducing into the wall of the fiber polymerizable liquid monomers, and polymerizing the monomers therein to form solid, insoluble, cross-linked, ion-exchange resin particles which embed in the wall of the fiber. Excess particles blocking the central passage or bore of the fiber are removed by forcing liquid through the fiber. The fibers have high ion-exchange capacity, a practical wall permeability and good mechanical strength even with very thin wall dimensions. Experimental investigation of bundles of ion-exchange hollow fibers attached to a header assembly have shown the fiber to be very efficient in removing counterions from solution.

  14. Hollow waveguide for urology treatment

    NASA Astrophysics Data System (ADS)

    Jelínková, H.; Němec, M.; Koranda, P.; Pokorný, J.; Kőhler, O.; Drlík, P.; Miyagi, M.; Iwai, K.; Matsuura, Y.

    2010-02-01

    The aim of our work was the application of the special sealed hollow waveguide system for the urology treatment - In our experimental study we have compared the effects of Ho:YAG (wavelength 2100 nm) and Er:YAG (wavelength 2940 nm) laser radiation both on human urinary stones (or compressed plaster samples which serve as a model) fragmentation and soft ureter tissue incision in vitro. Cyclic Olefin Polymer - coated silver (COP/Ag) hollow glass waveguides with inner and outer diameters 700 and 850 μm, respectively, were used for the experiment. To prevent any liquid to diminish and stop the transmission, the waveguide termination was utilized.

  15. Metal hybrid nanoparticles for catalytic organic and photochemical transformations.

    PubMed

    Song, Hyunjoon

    2015-03-17

    functions, such as magnetism and light absorption, to the catalytic properties. In particular, metal-semiconductor hybrid nanostructures could behave as effective visible photocatalysts for hydrogen evolution and CO oxidation reactions. Resulting from the large surface area and high local concentration of the reactants, a double-shell hollow structure showed reaction activities higher than those of filled nanoparticles. The introduction of plasmonic Au probes into the Pt-CdS double-shell hollow particles facilitated the monitoring of photocatalytic hydrogen generation that occurred on an individual particle surface by single particle measurements. Further development of catalysis research using well-defined metal hybrid nanocatalysts with various in situ spectroscopic tools provides a means of maximizing catalytic performances until they are comparable to or better than those of homogeneous catalysts, and this would have possibly useful implications for industrial applications.

  16. Growth of solid and hollow gold particles through the thermal annealing of nanoscale patterned thin films

    SciTech Connect

    Lin, Junhao; He, Weidong; Vilayur Ganapathy, Subramanian; Peppernick, Samuel J.; Wang, Bin; Palepu, Sandeep; Remec, Miroslav; Hess, Wayne P.; Hmelo, Anthony B.; Pantelides, Sokrates T.; Dickerson, James

    2013-11-27

    Through thermally annealing well-arrayed, circular, nanoscale thin films of gold, deposited onto [111] silicon/silicon dioxide substrates, both solid and hollow gold particles of different morphologies with controllable sizes were obtained. The thin film could form individual particle or clusters of particles by tuning the diameter of it. Hollow gold particles were featured by their large size whose diameter was larger than 500 nm and confirmed by a cross-section view. Hollow gold particles show greater plasmonic field enhancement under photoemission electron microscopy. Potential growth mechanisms for these structures are explored

  17. Hollow vortices in weakly compressible flows

    NASA Astrophysics Data System (ADS)

    Krishnamurthy, Vikas; Crowdy, Darren

    2015-11-01

    In a two-dimensional, inviscid and steady fluid flow, hollow vortices are bounded regions of constant pressure with non-zero circulation. It is known that for an infinite row of incompressible hollow vortices, analytical solutions for the flow field and the shape of the hollow vortex boundary can be obtained using conformal mapping methods. In this talk, we show how to derive analytical expressions for a weakly compressible hollow vortex row. This is done by introducing a new method based on the Imai-Lamla formula. We will also touch upon how to extend these results to a von-Karman street of hollow vortices.

  18. Facile preparation of well-dispersed CeO2-ZnO composite hollow microspheres with enhanced catalytic activity for CO oxidation.

    PubMed

    Xie, Qingshui; Zhao, Yue; Guo, Huizhang; Lu, Aolin; Zhang, Xiangxin; Wang, Laisen; Chen, Ming-Shu; Peng, Dong-Liang

    2014-01-01

    In this article, well-dispersed CeO2-ZnO composite hollow microspheres have been fabricated through a simple chemical reaction followed by annealing treatment. Amorphous zinc-cerium citrate hollow microspheres were first synthesized by dispersing zinc citrate hollow microspheres into cerium nitrate solution and then aging at room temperature for 1 h. By calcining the as-produced zinc-cerium citrate hollow microspheres at 500 °C for 2 h, CeO2-ZnO composite hollow microspheres with homogeneous composition distribution could be harvested for the first time. The resulting CeO2-ZnO composite hollow microspheres exhibit enhanced activity for CO oxidation compared with CeO2 and ZnO, which is due to well-dispersed small CeO2 particles on the surface of ZnO hollow microspheres and strong interaction between CeO2 and ZnO. Moreover, when Au nanoparticles are deposited on the surface of the CeO2-ZnO composite hollow microspheres, the full CO conversion temperature of the as-produced 1.0 wt % Au-CeO2-ZnO composites reduces from 300 to 60 °C in comparison with CeO2-ZnO composites. The significantly improved catalytic activity may be ascribed to the strong synergistic interplay between Au nanoparticles and CeO2-ZnO composites.

  19. Hollow electrode plasma excitation source

    DOEpatents

    Ballou, Nathan E.

    1992-01-01

    A plasma source incorporates a furnace as a hollow anode, while a coaxial cathode is disposed therewithin. The source is located in a housing provided with an ionizable gas such that a glow discharge is produced between anode and cathode. Radiation or ionic emission from the glow discharge characterizes a sample placed within the furnace and heated to elevated temperatures.

  20. Hollow waveguide cavity ringdown spectroscopy

    NASA Technical Reports Server (NTRS)

    Dreyer, Chris (Inventor); Mungas, Greg S. (Inventor)

    2012-01-01

    Laser light is confined in a hollow waveguide between two highly reflective mirrors. This waveguide cavity is used to conduct Cavity Ringdown Absorption Spectroscopy of loss mechanisms in the cavity including absorption or scattering by gases, liquid, solids, and/or optical elements.

  1. Hollow electrode plasma excitation source

    DOEpatents

    Ballou, N.E.

    1992-04-14

    A plasma source incorporates a furnace as a hollow anode, while a coaxial cathode is disposed therewithin. The source is located in a housing provided with an ionizable gas such that a glow discharge is produced between anode and cathode. Radiation or ionic emission from the glow discharge characterizes a sample placed within the furnace and heated to elevated temperatures. 5 figs.

  2. Hollow Plasma in a Solenoid

    SciTech Connect

    Anders, Andre; Kauffeldt, Marina; Oks, Efim M.; Roy, Prabir K.

    2010-11-30

    A ring cathode for a pulsed, high-current, multi-spot cathodic arc discharge was placed inside a pulsed magnetic solenoid. Photography is used to evaluate the plasma distribution. The plasma appears hollow for cathode positions close the center of the solenoid, and it is guided closer to the axis when the cathode is away from the center.

  3. Hollow cathodes for arcjet thrusters

    NASA Technical Reports Server (NTRS)

    Luebben, Craig R.; Wilbur, Paul J.

    1987-01-01

    In an attempt to prevent exterior spot emission, hollow cathode bodies and orifice plates were constructed from boron nitride which is an electrical insulator, but the orifice plates melted and/or eroded at high interelectrode pressures. The most suitable hollow cathodes tested included a refractory metal orifice plate in a boron nitride body, with the insert insulated electrically from the orifice plate. In addition, the hollow cathode interior was evacuated to assure a low pressure at the insert surface, thus promoting diffuse electron emission. At high interelectrode pressures, the electrons tended to flow through the orifice plate rather than through the orifice, which could result in overheating of the orifice plate. Using a carefully aligned centerline anode, electron flow through the orifice could be sustained at interelectrode pressures up to 500 torr - but the current flow path still occasionally jumped from the orifice to the orifice plate. Based on these tests, it appears that a hollow cathode would operate most effectively at pressures in the arcjet regime with a refractory, chemically stable, and electrically insulating cathode body and orifice plate.

  4. High Pressure Hollow Cathode Discharges

    NASA Astrophysics Data System (ADS)

    Schoenbach, Karl H.; Tessnow, Thomas; Elhabachi, Ahmed

    1996-10-01

    The sustaining voltage of hollow cathode discharges is dependent on the product of pressure and cathode hole diameter. By reducing the dimension of the cathode hole to 0.2 mm we were able to operate micro-hollow cathode discharges at pressures up to 750 Torr in argon in a direct current mode. The current-voltage characteristics of the 0.2 mm cathode hole discharges was found to have a positive slope at currents below 0.25 mA. Up to this current level hollow cathode discharges can be operated in parallel without ballast. The negative slope observed above the threshold current seems to be due to the onset of thermionic electron emission caused by Joule heating of the cathode. This assumption is supported by the experimental observation that multi-hole operation without ballast even at currents far above the dc-threshold current was possible when the discharge was operated in a pulsed mode. The possibility of generating large arrays of ballast-free, pulsed micro-hollow cathode discharges suggests their use as flat panel light sources or electron sources.

  5. Energy transfer from an individual silica nanoparticle to graphene quantum dots and resulting enhancement of photodetector responsivity

    PubMed Central

    Kim, Sung; Shin, Dong Hee; Kim, Jungkil; Jang, Chan Wook; Kang, Soo Seok; Kim, Jong Min; Kim, Ju Hwan; Lee, Dae Hun; Kim, Jung Hyun; Choi, Suk-Ho; Hwang, Sung Won

    2016-01-01

    Förster resonance energy transfer (FRET), referred to as the transfer of the photon energy absorbed in donor to acceptor, has received much attention as an important physical phenomenon for its potential applications in optoelectronic devices as well as for the understanding of some biological systems. If one-atom-thick graphene is used for donor or acceptor, it can minimize the separation between donor and acceptor, thereby maximizing the FRET efficiency (EFRET). Here, we report first fabrication of a FRET system composed of silica nanoparticles (SNPs) and graphene quantum dots (GQDs) as donors and acceptors, respectively. The FRET from SNPs to GQDs with an EFRET of ∼78% is demonstrated from excitation-dependent photoluminescence spectra and decay curves. The photodetector (PD) responsivity (R) of the FRET system at 532 nm is enhanced by 100∼101/102∼103 times under forward/reverse biases, respectively, compared to the PD containing solely GQDs. This remarkable enhancement is understood by network-like current paths formed by the GQDs on the SNPs and easy transfer of the carriers generated from the SNPs into the GQDs due to their close attachment. The R is 2∼3 times further enhanced at 325 nm by the FRET effect. PMID:27250343

  6. Energy transfer from an individual silica nanoparticle to graphene quantum dots and resulting enhancement of photodetector responsivity

    NASA Astrophysics Data System (ADS)

    Kim, Sung; Shin, Dong Hee; Kim, Jungkil; Jang, Chan Wook; Kang, Soo Seok; Kim, Jong Min; Kim, Ju Hwan; Lee, Dae Hun; Kim, Jung Hyun; Choi, Suk-Ho; Hwang, Sung Won

    2016-06-01

    Förster resonance energy transfer (FRET), referred to as the transfer of the photon energy absorbed in donor to acceptor, has received much attention as an important physical phenomenon for its potential applications in optoelectronic devices as well as for the understanding of some biological systems. If one-atom-thick graphene is used for donor or acceptor, it can minimize the separation between donor and acceptor, thereby maximizing the FRET efficiency (EFRET). Here, we report first fabrication of a FRET system composed of silica nanoparticles (SNPs) and graphene quantum dots (GQDs) as donors and acceptors, respectively. The FRET from SNPs to GQDs with an EFRET of ∼78% is demonstrated from excitation-dependent photoluminescence spectra and decay curves. The photodetector (PD) responsivity (R) of the FRET system at 532 nm is enhanced by 100∼101/102∼103 times under forward/reverse biases, respectively, compared to the PD containing solely GQDs. This remarkable enhancement is understood by network-like current paths formed by the GQDs on the SNPs and easy transfer of the carriers generated from the SNPs into the GQDs due to their close attachment. The R is 2∼3 times further enhanced at 325 nm by the FRET effect.

  7. Measuring bandgap states in individual non-stoichiometric oxide nanoparticles using monochromated STEM EELS: The Praseodymium-ceria case.

    PubMed

    Bowman, W J; March, K; Hernandez, C A; Crozier, P A

    2016-08-01

    We describe a method to perform high spatial resolution measurement of the position and density of inter-band impurity states in non-stoichiometric oxides using ultra-high energy resolution electron energy-loss spectroscopy (EELS). This can be employed to study optical and electronic properties of atomic and nanoscale defects in electrically-conducting and optically-active oxides. We employ a monochromated scanning transmission electron microscope with subnanometer diameter electron probe, making this technique suitable for correlating spectroscopic information with high spatial resolution images from small objects such as nanoparticles, surfaces or interfaces. The specific experimental approach outlined here provides direct measurement of the Pr inter-band impurity states in Pr0.1Ce0.9O2-δ via valence-loss EELS, which is interpreted with valence-loss spectral simulation based on density of states data to determine the energy level and character of the inter-band state. Additionally, observation of optical color change upon chemically-induced oxygen non-stoichiometry indicates that the population of the inter-band state is accompanied by an energy level shift within the bandgap.

  8. Measuring bandgap states in individual non-stoichiometric oxide nanoparticles using monochromated STEM EELS: The Praseodymium-ceria case.

    PubMed

    Bowman, W J; March, K; Hernandez, C A; Crozier, P A

    2016-08-01

    We describe a method to perform high spatial resolution measurement of the position and density of inter-band impurity states in non-stoichiometric oxides using ultra-high energy resolution electron energy-loss spectroscopy (EELS). This can be employed to study optical and electronic properties of atomic and nanoscale defects in electrically-conducting and optically-active oxides. We employ a monochromated scanning transmission electron microscope with subnanometer diameter electron probe, making this technique suitable for correlating spectroscopic information with high spatial resolution images from small objects such as nanoparticles, surfaces or interfaces. The specific experimental approach outlined here provides direct measurement of the Pr inter-band impurity states in Pr0.1Ce0.9O2-δ via valence-loss EELS, which is interpreted with valence-loss spectral simulation based on density of states data to determine the energy level and character of the inter-band state. Additionally, observation of optical color change upon chemically-induced oxygen non-stoichiometry indicates that the population of the inter-band state is accompanied by an energy level shift within the bandgap. PMID:27152715

  9. Direct view on the phase evolution in individual LiFePO4 nanoparticles during Li-ion battery cycling

    PubMed Central

    Zhang, Xiaoyu; van Hulzen, Martijn; Singh, Deepak P.; Brownrigg, Alex; Wright, Jonathan P.; van Dijk, Niels H.; Wagemaker, Marnix

    2015-01-01

    Phase transitions in Li-ion electrode materials during (dis)charge are decisive for battery performance, limiting high-rate capabilities and playing a crucial role in the cycle life of Li-ion batteries. However, the difficulty to probe the phase nucleation and growth in individual grains is hindering fundamental understanding and progress. Here we use synchrotron microbeam diffraction to disclose the cycling rate-dependent phase transition mechanism within individual particles of LiFePO4, a key Li-ion electrode material. At low (dis)charge rates well-defined nanometer thin plate-shaped domains co-exist and transform much slower and concurrent as compared with the commonly assumed mosaic transformation mechanism. As the (dis)charge rate increases phase boundaries become diffuse speeding up the transformation rates of individual grains. Direct observation of the transformation of individual grains reveals that local current densities significantly differ from what has previously been assumed, giving new insights in the working of Li-ion battery electrodes and their potential improvements. PMID:26395323

  10. Magnetically separable and recyclable Fe3O4-polydopamine hybrid hollow microsphere for highly efficient peroxidase mimetic catalysts.

    PubMed

    Liu, Shujun; Fu, Jianwei; Wang, Minghuan; Yan, Ya; Xin, Qianqian; Cai, Lu; Xu, Qun

    2016-05-01

    Magnetic Fe3O4-polydopamine (PDA) hybrid hollow microspheres, in which Fe3O4 nanoparticles were firmly incorporated in the cross-linked PDA shell, have been prepared through the formation of core/shell PS/Fe3O4-PDA composites based on template-induced covalent assembly method, followed by core removal in a tetrahydrofuran solution. The morphology, composition, thermal property and magnetic property of the magnetic hybrid hollow microspheres were characterized by SEM, TEM, FT-IR, XRD, TGA, and vibrating sample magnetometer, respectively. Results revealed that the magnetic hybrid hollow microspheres had about 380 nm of inner diameter and about 30 nm of shell thickness, and 13.6 emu g(-1) of magnetization saturation. More importantly, the Fe3O4-PDA hybrid hollow microspheres exhibited intrinsic peroxidase-like activity, as they could quickly catalyze the oxidation of typical substrates 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide. Compared with PDA/Fe3O4 composites where Fe3O4 nanoparticles were loaded on the surface of PDA microspheres, the stability of Fe3O4-PDA hybrid hollow microspheres was greatly improved. As-prepared magnetic hollow microspheres might open up a new application field in biodetection, biocatalysis, and environmental monitoring.

  11. Facile synthesis of hollow Cu2O octahedral and spherical nanocrystals and their morphology-dependent photocatalytic properties

    PubMed Central

    2012-01-01

    Herein, we report that octahedral and spherical Cu2O samples with hollow structures are synthesized in high yield by reducing Cu(EDA)22+ complex with hydrazine. A series of experiments are carried out to investigate the factors which impact on the morphology of the Cu2O samples. It is observed that ethylenediamine (EDA) serves as a molecular template in the formation of hollow structure. Octahedral Cu2O with solid structure is prepared without EDA. When EDA is added, Cu2O sample with hollow structure is formed. Different morphologies of Cu2O such as spherical and octahedral could be obtained by adjusting the concentration of EDA and NaOH. The temporal crystal growth mechanism is proposed. Furthermore, the photocatalytic activities of the as-prepared Cu2O nanoparticles are evaluated by monitoring two dyes (methyl orange and congo red) using UV-visible spectrophotometer. Results show that the order of photocatalytic activity of Cu2O with different morphologies is as follows: hollow octahedral morphology > hollow sphere morphology > solid octahedral morphology. The hollow octahedral Cu2O nanoparticles would be a promising material on applications for photocatalytic degradation of organic pollutants. PMID:22647408

  12. Fabrication and upconversion luminescence properties of YF3:Er3+ hollow nanofibers via monoaxial electrospinning combined with fluorination method.

    PubMed

    Li, Dan; Dong, Xiangting; Yu, Wensheng; Wang, Jinxian; Liu, Guixia

    2014-06-01

    YF3:Er3+ hollow nanofibers were successfully fabricated via fluorination of the relevant Y2O3:Er3+ hollow nanofibers which were obtained by calcining the electrospun PVP/[Y(NO3)3 + Er(NO3)3] composite nanofibers. The morphology and properties of the products were investigated in detail by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and fluorescence spectrometer. YF3:Er3+ hollow nanofibers were pure orthorhombic phase with space group Pnma and were hollow-centered structure with the mean diameter of 172 +/- 23 nm, and YF3:Er3+ hollow nanofibers were composed of nanoparticles with the diameter ranging from 30 nm to 50 nm. Upconversion emission spectrum analysis manifested that YF3:Er3+ hollow nanofibers emitted strong green and weak red upconversion emission centering at 524 nm, 543 nm and 653 nm, respectively. The green emissions and the red emission were respectively originated from 2H11/2/4S3/2 --> 4I15/2 and 4F9/2 --> 4I15/2 energy levels transitions of the Er3+ ions. Moreover, the emitting colors of YF3:Er3+ hollow nanofibers were located in the green region in CIE chromaticity coordinates diagram. The luminescent intensity of YF3:Er3+ hollow nanofibers was increased remarkably with the increasing doping concentration of Er3+ ions. The possible formation mechanism of YF3:Er3+ upconversion luminescence hollow nanofibers was also discussed. This preparation technique could be applied to prepare other rare earth fluoride upconversion luminescence hollow nanofibers.

  13. Well-defined hollow nanochanneled-silica nanospheres prepared with the aid of sacrificial copolymer nanospheres and surfactant nanocylinders.

    PubMed

    Kim, Young Yong; Hwang, Bora; Song, Sungjin; Ree, Brian J; Kim, Yongjin; Cho, Seo Yeon; Heo, Kyuyoung; Kwon, Yong Ku; Ree, Moonhor

    2015-09-21

    A new approach for synthesizing well-defined hollow nanochanneled-silica nanosphere particles is demonstrated, and the structural details of these particles are described for the first time. Positively charged styrene copolymer nanospheres with a clean, smooth surface and a very narrow size distribution are synthesized by surfactant-free emulsion copolymerization and used as a thermal sacrificial core template for the production of core-shell nanoparticles. A surfactant/silica composite shell with a uniform thickness is successfully produced and deposited onto the polymeric core template by charge density matching between the polymer nanosphere template surface and the negatively charged silica precursors and then followed by selective thermal decomposition of the polymeric core and the surfactant cylinder domains in the shell, producing the hollow nanochanneled-silica nanospheres. Comprehensive, quantitative structural analyses collectively confirm that the obtained nanoparticles are structurally well defined with a hollow core and a shell composed of cylindrical nanochannels that provide facile accessibility to the hollow interior space. Overall, the hollow nanochanneled-silica nanoparticles have great potential for applications in various fields. PMID:26287395

  14. Enzyme-Powered Hollow Mesoporous Janus Nanomotors.

    PubMed

    Ma, Xing; Jannasch, Anita; Albrecht, Urban-Raphael; Hahn, Kersten; Miguel-López, Albert; Schäffer, Erik; Sánchez, Samuel

    2015-10-14

    The development of synthetic nanomotors for technological applications in particular for life science and nanomedicine is a key focus of current basic research. However, it has been challenging to make active nanosystems based on biocompatible materials consuming nontoxic fuels for providing self-propulsion. Here, we fabricate self-propelled Janus nanomotors based on hollow mesoporous silica nanoparticles (HMSNPs), which are powered by biocatalytic reactions of three different enzymes: catalase, urease, and glucose oxidase (GOx). The active motion is characterized by a mean-square displacement (MSD) analysis of optical video recordings and confirmed by dynamic light scattering (DLS) measurements. We found that the apparent diffusion coefficient was enhanced by up to 83%. In addition, using optical tweezers, we directly measured a holding force of 64 ± 16 fN, which was necessary to counteract the effective self-propulsion force generated by a single nanomotor. The successful demonstration of biocompatible enzyme-powered active nanomotors using biologically benign fuels has a great potential for future biomedical applications. PMID:26437378

  15. Multiple Hollow Cathode Wear Testing

    NASA Technical Reports Server (NTRS)

    Soulas, George C.

    1994-01-01

    A hollow cathode-based plasma contactor has been baselined for use on the Space Station to reduce station charging. The plasma contactor provides a low impedance connection to space plasma via a plasma produced by an arc discharge. The hollow cathode of the plasma contactor is a refractory metal tube, through which xenon gas flows, which has a disk-shaped plate with a centered orifice at the downstream end of the tube. Within the cathode, arc attachment occurs primarily on a Type S low work function insert that is next to the orifice plate. This low work function insert is used to reduce cathode operating temperatures and energy requirements and, therefore, achieve increased efficiency and longevity. The operating characteristics and lifetime capabilities of this hollow cathode, however, are greatly reduced by oxygen bearing contaminants in the xenon gas. Furthermore, an optimized activation process, where the cathode is heated prior to ignition by an external heater to drive contaminants such as oxygen and moisture from the insert absorbed during exposure to ambient air, is necessary both for cathode longevity and a simplified power processor. In order to achieve the two year (approximately 17,500 hours) continuous operating lifetime requirement for the plasma contactor, a test program was initiated at NASA Lewis Research Center to demonstrate the extended lifetime capabilities of the hollow cathode. To date, xenon hollow cathodes have demonstrated extended lifetimes with one test having operated in excess of 8000 hours in an ongoing test utilizing contamination control protocols developed by Sarver-Verhey. The objectives of this study were to verify the transportability of the contamination control protocols developed by Sarver-Verhey and to evaluate cathode contamination control procedures, activation processes, and cathode-to-cathode dispersions in operating characteristics with time. These were accomplished by conducting a 2000 hour wear test of four hollow

  16. Synthesis, purification and assembly of gold and iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Qiu, Penghe

    , 6 & 7), nanoparticles were assembled into three different hierachical structures through both template-assisted and template-free approaches. In the template-assisted assembly, gold nanorods were aligned into ordered 1D linear pattern by using soft biological filamentous, namely bacteria flagella, as templates. Two different ways of assembling nanorods onto flagella were investigated. In another study, a highly commercialized polymer, polyvinylpyrrolidone (PVP), was discovered for the first time to be able to self-assemble into branched hollow fibers. Based on this discovery, two approaches (one through direct deposition of silica onto the PVP aggregate and the other through co-assembly of PVP covered gold nanoparticles with free PVP molecules) by which the self-assembly behavior of PVP could be exploited to template the formation of branched hollow inorganic fibers were demonstrated. In the template-free assembly, a general method for assembling nanoparticle into clusters (NPCs) in an oil-in-water emulsion system was investigated. Detailed studies on the mechanism of formation of NPCs structure, optimized conditions, scalable production and surface chemistry manipulation were carried out. Besides, comparison of the properties of individual and clustered iron oxide nanoparticles was conducted. It was discovered that due to their collective properties, NPCs are more responsive to an external magnetic field and can potentially serve as better contrast enhancement agents than individually dispersed magnetic NPs in Magnetic Resonance Imaging (MRI).

  17. Template-free synthesis of ZnV 2O 4 hollow spheres and their application for organic dye removal

    NASA Astrophysics Data System (ADS)

    Duan, Fang; Dong, Weifu; Shi, Dongjian; Chen, Mingqing

    2011-10-01

    Hollow ZnV 2O 4 spheres with the shell aggregated by small nanoparticles were successfully synthesized through a facile one-pot template-free solvothermal method. The as-prepared product was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), and Brunauer-Emmett-Teller N 2 adsorption-desorption analyses. The formation of ZnV 2O 4 hollow spheres was based on flowerlike intermediate products supported reduction-dissolution-aggregation process at the expense of consumption of all the flowerlike products. The obtained ZnV 2O 4 hollow spheres showed a good adsorption capacity of methylene blue (MB) organic dye, which might be attributed to their special structural feature with large surface area. The adsorption kinetics and isotherm of MB on ZnV 2O 4 hollow spheres were also studied.

  18. Controllable synthesis of helical, straight, hollow and nitrogen-doped carbon nanofibers and their magnetic properties

    SciTech Connect

    Li, Xun; Xu, Zheng

    2012-12-15

    Graphical abstract: The helical, straight and hollow carbon nanofibers can be selectively synthesized by adjusting either the reaction temperature or feed gas composition. Display Omitted Highlights: ► CNFs were synthesized via pyrolysis of acetylene on copper NPs. ► The helical, straight, hollow and N-doped CNFs can be selectively synthesized. ► The growth mechanism of different types of CNFs was proposed. -- Abstract: Carbon nanofibers (CNFs) with various morphologies were synthesized by catalytic pyrolysis of acetylene on copper nanoparticles which were generated from the in situ decomposition of copper acetylacetonate. The morphology of the pristine and acid-washed CNFs was investigated by field emission scanning electron microscope and high-resolution transmission electron microscope. Helical, straight and hollow CNFs can be selectively synthesized by adjusting either the reaction temperature or feed gas composition. The growth mechanism for these three types of CNFs was proposed.

  19. Hydrogen hollow cathode ion source

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J., Jr.; Sovey, J. S.; Roman, R. F. (Inventor)

    1980-01-01

    A source of hydrogen ions is disclosed and includes a chamber having at one end a cathode which provides electrons and through which hydrogen gas flows into the chamber. Screen and accelerator grids are provided at the other end of the chamber. A baffle plate is disposed between the cathode and the grids and a cylindrical baffle is disposed coaxially with the cathode at the one end of the chamber. The cylindrical baffle is of greater diameter than the baffle plate to provide discharge impedance and also to protect the cathode from ion flux. An anode electrode draws the electrons away from the cathode. The hollow cathode includes a tubular insert of tungsten impregnated with a low work function material to provide ample electrons. A heater is provided around the hollow cathode to initiate electron emission from the low work function material.

  20. Photochemical preparation of CdS hollow microspheres at room temperature and their use in visible-light photocatalysis

    SciTech Connect

    Huang Yuying; Sun Fengqiang; Wu Tianxing; Wu Qingsong; Huang Zhong; Su Heng; Zhang Zihe

    2011-03-15

    CdS hollow microspheres have been successfully prepared by a photochemical preparation technology at room temperature, using polystyrene latex particles as templates, CdSO{sub 4} as cadmium source and Na{sub 2}S{sub 2}O{sub 3} as both sulphur source and photo-initiator. The process involved the deposition of CdS nanoparticles on the surface of polystyrene latex particles under the irradiation of an 8 W UV lamp and the subsequent removal of the latex particles by dispersing in dichloromethane. Photochemical reactions at the sphere/solution interface should be responsible for the formation of hollow spheres. The as-prepared products were characterized by X-ray diffraction, transmission electron microscopy and scanning electron microscopy. Such hollow spheres could be used in photocatalysis and showed high photocatalytic activities in photodegradation of methyl blue (MB) in the presence of H{sub 2}O{sub 2}. The method is green, simple, universal and can be extended to prepare other sulphide and oxide hollow spheres. -- Graphical abstract: Taking polystyrene spheres dispersed in a precursor solution as templates, CdS hollow microspheres composed of nanoparticles were successfully prepared via a new photochemical route at room temperature. Display Omitted Research highlights: {yields} Photochemical method was first employed to prepare hollow microspheres. {yields} CdS hollow spheres were first prepared at room temperature using latex spheres. {yields} The polystyrene spheres used as templates were not modified with special groups. {yields}The CdS hollow microspheres showed high visible-light photocatalytic activities.

  1. Micro-hollow cathode dischargers

    SciTech Connect

    Schoenbach, K.H.; Verhappen, R.; Peterkin, F.E.

    1995-12-31

    In order to develop a hollow cathode discharge (HCD) with its increased current over planar electrode glow discharges, the cathode fall, which is on the order of the mean free path for ionization, must be comparable in length to the hole diameter. This indicates that the discharge parameters vary with pressure, p, times hole diameter, D. The pD product for stable operation of a hollow cathosde discharge was quoted to be on the order of one to ten Torr cm for noble gases, less for molecular gases. White (1959) observed the hollow cathode effect in a neon discharge at a pressure of 100 Torr when the hole dimensions were less than 1 mm. The cathode hole in his experiments changed from a cylindrical into a spherical cavity due to sputtering. The anode consisted in White`s experiment of a pin on the axis of the discharge geometry. We have studied micro-hollow (submillimeter) cathode discharges between two electrodes with aligned cylindrical holes by determining the current-voltage characteristics and the visual appearance of the discharge in argon over a wide range of pressure and voltage. The cross-section of the discharge geometry. The cathode is made of molybdenum or barium oxide inserted into a tungsten matrix (dispenser-cathode), the anode of molybdenum, and the dielectric spacer is mica. The discharge was operated under dc conditions, with half-wave rectified ac voltage applied, and pulsed with a 400 {mu}s rectangular voltage pulse. The lower limit in pressure was determined by the maximum voltage which could be applied to the discharge geometry without breakdown along insulators. The upper limit, in this study, is determined by the transition from cathode electrode emission due to ion-impact to thermal emission of electrons, which causes a dramatic increase in current and a drop in forward voltage to values on the order of 20 V.

  2. 78 FR 60271 - Hollow Dam Power Company; Ampersand Hollow Dam Hydro, LLC; Notice of Application for Transfer of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-01

    ... Federal Energy Regulatory Commission Hollow Dam Power Company; Ampersand Hollow Dam Hydro, LLC; Notice of..., Hollow Dam Power Company (transferor) and Ampersand Hollow Dam Hydro, LLC (transferee) filed an application for transfer of license for the Hollow Dam Project, FERC No. 6972, located on the West Branch...

  3. Cascade decays of hollow ions

    SciTech Connect

    Omar, G. ); Hahn, Y. )

    1991-05-01

    A multiple-electron-emission process for atoms with one or more inner-shell vacancies is treated using the radiative- and Auger-electron-emission cascade model, in which inner-shell holes are assumed to decay by sequentially emitting radiations and/or Auger electrons. Such hollow ions are produced by synchrotron irradiation of atomic targets and in ion-surface interactions with multiple-electron transfers. The final charge-state distribution is determined by the Auger and radiative branching ratios at each stage of the decay sequence. At intermediate stages of cascade, hollow ions with more than one hole in different ionization stages are created. The Ne, Mg, and Fe{sup 14+} ions with the initial 1{ital s}, 2{ital s}, and 2{ital p} vacancies are considered in detail, and the core charge dependence of the maximum charge state is studied. The hollow Mg ion with double initial 1{ital s} holes is analyzed, and the result compared with that for the case of one 1{ital s} hole. The peak is shifted more than two units to a higher degree of ionization. The correlated shake-off and shake-up multiple-electron processes are not considered, but they are expected to cause further shifts.

  4. Method to fabricate hollow microneedle arrays

    DOEpatents

    Kravitz, Stanley H.; Ingersoll, David; Schmidt, Carrie; Flemming, Jeb

    2006-11-07

    An inexpensive and rapid method for fabricating arrays of hollow microneedles uses a photoetchable glass. Furthermore, the glass hollow microneedle array can be used to form a negative mold for replicating microneedles in biocompatible polymers or metals. These microneedle arrays can be used to extract fluids from plants or animals. Glucose transport through these hollow microneedles arrays has been found to be orders of magnitude more rapid than natural diffusion.

  5. Process for making hollow carbon spheres

    DOEpatents

    Luhrs, Claudia C.; Phillips, Jonathan; Richard, Monique N.; Knapp, Angela Michelle

    2013-04-16

    A hollow carbon sphere having a carbon shell and an inner core is disclosed. The hollow carbon sphere has a total volume that is equal to a volume of the carbon shell plus an inner free volume within the carbon shell. The inner free volume is at least 25% of the total volume. In some instances, a nominal diameter of the hollow carbon sphere is between 10 and 180 nanometers.

  6. Hollow fibers for compact infrared gas sensors

    NASA Astrophysics Data System (ADS)

    Lambrecht, A.; Hartwig, S.; Herbst, J.; Wöllenstein, J.

    2008-02-01

    Hollow fibers can be used for compact infrared gas sensors. The guided light is absorbed by the gas introduced into the hollow core. High sensitivity and a very small sampling volume can be achieved depending on fiber parameters i.e. attenuation, flexibility, and gas exchange rates. Different types of infrared hollow fibers including photonic bandgap fibers were characterized using quantum cascade lasers and thermal radiation sources. Obtained data are compared with available product specifications. Measurements with a compact fiber based ethanol sensor are compared with a system simulation. First results on the detection of trace amounts of the explosive material TATP using hollow fibers and QCL will be shown.

  7. TiO2 hollow spheres composed of highly crystalline nanocrystals exhibit superior lithium storage properties.

    PubMed

    Zhang, Genqiang; Wu, Hao Bin; Song, Taeseup; Paik, Ungyu; Lou, Xiong Wen David

    2014-11-10

    While the synthesis of TiO2 hollow structures is well-established, in most cases it is particularly difficult to control the crystallization of TiO2 in solution or by calcination. As a result, TiO2 hollow structures do not really exhibit enhanced lithium storage properties. Herein, we report a simple and cost-effective template-assisted method to synthesize anatase TiO2 hollow spheres composed of highly crystalline nanocrystals, in which carbonaceous (C) spheres are chosen as the removable template. The release of gaseous species from the combustion of C spheres may inhibit the growth of TiO2 crystallites so that instead small TiO2 nanocrystals are generated. The small size and high crystallinity of primary TiO2 nanoparticles and the high structural integrity of the hollow spheres gives rise to significant improvements in the cycling stability and rate performance of the TiO2 hollow spheres. PMID:25124735

  8. Electronically cloaked nanoparticles

    NASA Astrophysics Data System (ADS)

    Shen, Wenqing

    The concept of electronic cloaking is to design objects invisible to conduction electrons. The approach of electronic cloaking has been recently suggested to design invisible nanoparticle dopants with electronic scattering cross section smaller than 1% of the physical cross section (pi a2), and therefore to enhance the carrier mobility of bulk materials. The proposed nanoparticles have core-shell structures. The dopants are incorporated inside the core, while the shell layer serves both as a spacer to separate the charge carriers from their parent atoms and as a cloaking shell to minimize the scattering cross section of the electrons from the ionized nanoparticles. Thermoelectric materials are usually highly doped to have enough carrier density. Using invisible dopants could achieve larger thermoelectric power factors by enhancing the electronic mobility. Core-shell nanoparticles show an advantage over one-layer nanoparticles, which are proposed in three-dimensional modulation doping. However designing such nanoparticles is not easy as there are too many parameters to be considered. This thesis first shows an approach to design hollow nanoparticles by applying constrains on variables. In the second part, a simple mapping approach is introduced where one can identify possible core-shell particles by comparing the dimensionless parameters of chosen materials with provided maps. In both parts of this work, several designs with realistic materials were made and proven to achieve electronic cloaking. Improvement in the thermoelectric power factor compared to the traditional impurity doping method was demonstrated in several cases.

  9. Developments in Hollow Graphite Fiber Technology

    NASA Technical Reports Server (NTRS)

    Stallcup, Michael; Brantley, Lott W., Jr. (Technical Monitor)

    2002-01-01

    Hollow graphite fibers will be lighter than standard solid graphite fibers and, thus, will save weight in optical components. This program will optimize the processing and properties of hollow carbon fibers developed by MER and to scale-up the processing to produce sufficient fiber for fabricating a large ultra-lightweight mirror for delivery to NASA.

  10. The "House" in Half Hollow Hills

    ERIC Educational Resources Information Center

    Karnilow, Sheldon

    2006-01-01

    In this article, the author relates how he initiated a systemic improvement to Half Hollow Hills school district when he became its superintendent. He relates that although he came to Half Hollow Hills with a deep understanding of the models of systemic change, he did not bring with him a specific prescriptive plan for improvement. His plan for…

  11. Hollow nanocrystals and method of making

    DOEpatents

    Alivisatos, A. Paul; Yin, Yadong; Erdonmez, Can Kerem

    2011-07-05

    Described herein are hollow nanocrystals having various shapes that can be produced by a simple chemical process. The hollow nanocrystals described herein may have a shell as thin as 0.5 nm and outside diameters that can be controlled by the process of making.

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

    PubMed

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

    2015-10-01

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

  13. POROUS WALL, HOLLOW GLASS MICROSPHERES

    SciTech Connect

    Sexton, W.

    2012-06-30

    Hollow Glass Microspheres (HGM) is not a new technology. All one has to do is go to the internet and Google{trademark} HGM. Anyone can buy HGM and they have a wide variety of uses. HGM are usually between 1 to 100 microns in diameter, although their size can range from 100 nanometers to 5 millimeters in diameter. HGM are used as lightweight filler in composite materials such as syntactic foam and lightweight concrete. In 1968 a patent was issued to W. Beck of the 3M{trademark} Company for 'Glass Bubbles Prepared by Reheating Solid Glass Particles'. In 1983 P. Howell was issued a patent for 'Glass Bubbles of Increased Collapse Strength' and in 1988 H. Marshall was issued a patent for 'Glass Microbubbles'. Now Google{trademark}, Porous Wall, Hollow Glass Microspheres (PW-HGMs), the key words here are Porous Wall. Almost every article has its beginning with the research done at the Savannah River National Laboratory (SRNL). The Savannah River Site (SRS) where SRNL is located has a long and successful history of working with hydrogen and its isotopes for national security, energy, waste management and environmental remediation applications. This includes more than 30 years of experience developing, processing, and implementing special ceramics, including glasses for a variety of Department of Energy (DOE) missions. In the case of glasses, SRS and SRNL have been involved in both the science and engineering of vitreous or glass based systems. As a part of this glass experience and expertise, SRNL has developed a number of niches in the glass arena, one of which is the development of porous glass systems for a variety of applications. These porous glass systems include sol gel glasses, which include both xerogels and aerogels, as well as phase separated glass compositions, that can be subsequently treated to produce another unique type of porosity within the glass forms. The porous glasses can increase the surface area compared to 'normal glasses of a 1 to 2 order of

  14. Hollow metallic micromachined needles with multiple output ports

    NASA Astrophysics Data System (ADS)

    Brazzle, John D.; Mohanty, Swomitra K.; Frazier, A. Bruno

    1999-08-01

    In this paper, hollow metallic micromachined needles with multiple output ports are designed, fabricated, characterized, and packaged. The hollow metallic needles include design features such as tapered needle tips and multiple output ports on the bottom and top of each needle. The needle tip and shaft are formed by microelectroformed metal. The flow characteristics of the needles are currently being experimentally investigated and modeled using a finite element numerical model. The experimental results and theoretical models will be presented as part of this paper. The micromachined needles can be fabricated on a variety of substrates and can use micro-electroformed palladium as the structural material. The use of palladium as a structural material provides high mechanical strength and durability, as well as, biocompatibility for use in biomedical applications. The cross-sectional dimensions of individual needle tips begin at less than 10 micrometers in width and 15 micrometers in height and then taper to 200 micrometers in width and 60 micrometers in height. The significance of this work includes the development of hollow metallic micromachined needles for biomedical applications, as well as, a discussion of structural, fluidic, and packaging design considerations.

  15. Hollow gold nanorectangles: The roles of polarization and substrate

    NASA Astrophysics Data System (ADS)

    Near, Rachel D.; El-Sayed, Mostafa A.

    2013-07-01

    Dimers of hollow gold nanorectangles ((197 ± 4) × (134 ± 6) nm outside and (109 ± 5) × (53 ± 3) nm inside) were fabricated via electron beam lithography with interparticle separations ranging from 27 ± 2 nm to 596 ± 8 nm. Spectroscopic investigation of these arrays showed multiple peaks under illumination polarized both parallel and perpendicular to the interparticle axis. Discrete dipole approximation theoretical calculations were used to investigate the nature of these multiple peaks. These calculations demonstrate that the multiple peaks arise due to a combination of multiple plasmon modes and interactions with the substrate. The substrate effects are more pronounced for the parallel polarization because parallel polarization (along the long axis) of the nanorectangles results in a much stronger dipole mode than for the perpendicular polarization (along the short axis). Next, we show how these peaks change, as the hollow nanorectangles are brought within coupling range of one another. In this endeavor, we make use of our previously reported method to directly convert scanning electron microscope images of the nanoparticles into the shape files for the theoretical calculations.

  16. Hollow gold nanorectangles: the roles of polarization and substrate.

    PubMed

    Near, Rachel D; El-Sayed, Mostafa A

    2013-07-28

    Dimers of hollow gold nanorectangles ((197 ± 4) × (134 ± 6) nm outside and (109 ± 5) × (53 ± 3) nm inside) were fabricated via electron beam lithography with interparticle separations ranging from 27 ± 2 nm to 596 ± 8 nm. Spectroscopic investigation of these arrays showed multiple peaks under illumination polarized both parallel and perpendicular to the interparticle axis. Discrete dipole approximation theoretical calculations were used to investigate the nature of these multiple peaks. These calculations demonstrate that the multiple peaks arise due to a combination of multiple plasmon modes and interactions with the substrate. The substrate effects are more pronounced for the parallel polarization because parallel polarization (along the long axis) of the nanorectangles results in a much stronger dipole mode than for the perpendicular polarization (along the short axis). Next, we show how these peaks change, as the hollow nanorectangles are brought within coupling range of one another. In this endeavor, we make use of our previously reported method to directly convert scanning electron microscope images of the nanoparticles into the shape files for the theoretical calculations. PMID:23902009

  17. Formation of hollow silica nanospheres by reverse microemulsion

    NASA Astrophysics Data System (ADS)

    Lin, Cheng-Han; Chang, Jen-Hsuan; Yeh, Yi-Qi; Wu, Si-Han; Liu, Yi-Hsin; Mou, Chung-Yuan

    2015-05-01

    Uniform hollow silica nanospheres (HSNs) synthesized with reverse microemulsion have great application potential as nanoreactors because enzymes or nanocatalysts can be easily encapsulated de novo in synthesis. Water-in-oil (w/o) reverse microemulsions comprising the polymeric surfactant polyoxyethylene (5) isooctylphenyl ether (Igepal CA-520), ammonia and water in a continuous oil phase (alkanes) coalesce into size-tunable silica nanoparticles via diffusion aggregation after the introduction of silica precursors. Here, we elucidate in detail the growth mechanism for silica nanoparticles via nucleation of ammonium-catalyzed silica oligomers from tetraethylorthosilicate (TEOS) and nanoporous aminopropyltrimethoxy silane (APTS) in the reverse microemulsion system. The formation pathway was studied in situ with small-angle X-ray scattering (SAXS). We find a four-stage process showing a sigmoidal growth behavior in time with a crossover from the induction period, early nucleation stage, coalescence growth and a final slowing down of growth. Various characterizations (TEM, N2 isotherm, dynamic light scattering, zeta potential, NMR, elemental analysis) reveal the diameters, scattering length density (SLD), mesoporosity, surface potentials and chemical compositions of the HSNs. Oil phases of alkanes with different alkyl chains are systematically employed to tune the sizes of HSNs by varying oil molar volumes, co-solvent amounts or surfactant mixture ratios. Silica condensation is incomplete in the core region, with the silica source of TEOS and APTS leading to the hollow silica nanosphere after etching with warm water.Uniform hollow silica nanospheres (HSNs) synthesized with reverse microemulsion have great application potential as nanoreactors because enzymes or nanocatalysts can be easily encapsulated de novo in synthesis. Water-in-oil (w/o) reverse microemulsions comprising the polymeric surfactant polyoxyethylene (5) isooctylphenyl ether (Igepal CA-520), ammonia and

  18. Advantages of using gold hollow nanoshells in cancer photothermal therapy

    NASA Astrophysics Data System (ADS)

    Abbasi, Sattar; Servatkhah, Mojtaba; Keshtkar, Mohammad Mehdi

    2016-08-01

    Lots of studies have been conducted on the optical properties of gold nanoparticles in the first region of near infrared (650 nm–950 nm), however new findings show that the second region of near-infrared (1000 nm–1350 nm) penetrates to the deeper tissues of the human body. Therefore, using the above-mentioned region in photo-thermal therapy (PTT) of cancer will be more appropriate. In this paper, absorption efficiency is calculated for gold spherical and rod-shaped nanoshells by the finite element method (FEM). The results show that the surface plasmon frequency of these nanostructures is highly dependent on the dimension and thickness of shell and it can be adjusted to the second region of near-infrared. Thus, due to their optical tunability and their high absorption efficiency the hollow nanoshells are the most appropriate options for eradicating cancer tissues.

  19. Hollow titania spheres with movable silica spheres inside.

    PubMed

    Zhang, Kai; Zhang, Xuehai; Chen, Haitao; Chen, Xin; Zheng, Linli; Zhang, Junhu; Yang, Bai

    2004-12-21

    We demonstrate a flexible method for preparing hollow TiO2 nanospheres with movable silica nanoparticles inside (HTNMSNs). In this method, we used monodisperse silica--polystyrene core--shell nanospheres (SiO2-PS-CSNs) sulfonated as templates and prepared the composite shell consisting of TiO2 and sulfonated polystyrene (SPS) through adsorbing or depositing tetrabutyl titanate gel into the SPS shell. Finally the HTNMSNs were obtained after removal of all polymers in the composite nanospheres by dissolution or calcinations. We investigated the dependence of the morphologies of HTNMSNs on the thickness of PS shells and the size of SiO2 cores and prepared rare earth doped HTNMSNs by a sol-gel process.

  20. Advantages of using gold hollow nanoshells in cancer photothermal therapy

    NASA Astrophysics Data System (ADS)

    Abbasi, Sattar; Servatkhah, Mojtaba; Keshtkar, Mohammad Mehdi

    2016-08-01

    Lots of studies have been conducted on the optical properties of gold nanoparticles in the first region of near infrared (650 nm-950 nm), however new findings show that the second region of near-infrared (1000 nm-1350 nm) penetrates to the deeper tissues of the human body. Therefore, using the above-mentioned region in photo-thermal therapy (PTT) of cancer will be more appropriate. In this paper, absorption efficiency is calculated for gold spherical and rod-shaped nanoshells by the finite element method (FEM). The results show that the surface plasmon frequency of these nanostructures is highly dependent on the dimension and thickness of shell and it can be adjusted to the second region of near-infrared. Thus, due to their optical tunability and their high absorption efficiency the hollow nanoshells are the most appropriate options for eradicating cancer tissues.

  1. Design, synthesis and applications of core-shell, hollow core, and nanorattle multifunctional nanostructures

    NASA Astrophysics Data System (ADS)

    El-Toni, Ahmed Mohamed; Habila, Mohamed A.; Labis, Joselito Puzon; Alothman, Zeid A.; Alhoshan, Mansour; Elzatahry, Ahmed A.; Zhang, Fan

    2016-01-01

    With the evolution of nanoscience and nanotechnology, studies have been focused on manipulating nanoparticle properties through the control of their size, composition, and morphology. As nanomaterial research has progressed, the foremost focus has gradually shifted from synthesis, morphology control, and characterization of properties to the investigation of function and the utility of integrating these materials and chemical sciences with the physical, biological, and medical fields, which therefore necessitates the development of novel materials that are capable of performing multiple tasks and functions. The construction of multifunctional nanomaterials that integrate two or more functions into a single geometry has been achieved through the surface-coating technique, which created a new class of substances designated as core-shell nanoparticles. Core-shell materials have growing and expanding applications due to the multifunctionality that is achieved through the formation of multiple shells as well as the manipulation of core/shell materials. Moreover, core removal from core-shell-based structures offers excellent opportunities to construct multifunctional hollow core architectures that possess huge storage capacities, low densities, and tunable optical properties. Furthermore, the fabrication of nanomaterials that have the combined properties of a core-shell structure with that of a hollow one has resulted in the creation of a new and important class of substances, known as the rattle core-shell nanoparticles, or nanorattles. The design strategies of these new multifunctional nanostructures (core-shell, hollow core, and nanorattle) are discussed in the first part of this review. In the second part, different synthesis and fabrication approaches for multifunctional core-shell, hollow core-shell and rattle core-shell architectures are highlighted. Finally, in the last part of the article, the versatile and diverse applications of these nanoarchitectures in

  2. Design, synthesis and applications of core-shell, hollow core, and nanorattle multifunctional nanostructures.

    PubMed

    El-Toni, Ahmed Mohamed; Habila, Mohamed A; Labis, Joselito Puzon; ALOthman, Zeid A; Alhoshan, Mansour; Elzatahry, Ahmed A; Zhang, Fan

    2016-02-01

    With the evolution of nanoscience and nanotechnology, studies have been focused on manipulating nanoparticle properties through the control of their size, composition, and morphology. As nanomaterial research has progressed, the foremost focus has gradually shifted from synthesis, morphology control, and characterization of properties to the investigation of function and the utility of integrating these materials and chemical sciences with the physical, biological, and medical fields, which therefore necessitates the development of novel materials that are capable of performing multiple tasks and functions. The construction of multifunctional nanomaterials that integrate two or more functions into a single geometry has been achieved through the surface-coating technique, which created a new class of substances designated as core-shell nanoparticles. Core-shell materials have growing and expanding applications due to the multifunctionality that is achieved through the formation of multiple shells as well as the manipulation of core/shell materials. Moreover, core removal from core-shell-based structures offers excellent opportunities to construct multifunctional hollow core architectures that possess huge storage capacities, low densities, and tunable optical properties. Furthermore, the fabrication of nanomaterials that have the combined properties of a core-shell structure with that of a hollow one has resulted in the creation of a new and important class of substances, known as the rattle core-shell nanoparticles, or nanorattles. The design strategies of these new multifunctional nanostructures (core-shell, hollow core, and nanorattle) are discussed in the first part of this review. In the second part, different synthesis and fabrication approaches for multifunctional core-shell, hollow core-shell and rattle core-shell architectures are highlighted. Finally, in the last part of the article, the versatile and diverse applications of these nanoarchitectures in

  3. Microring embedded hollow polymer fiber laser

    SciTech Connect

    Linslal, C. L. Sebastian, S.; Mathew, S.; Radhakrishnan, P.; Nampoori, V. P. N.; Girijavallabhan, C. P.; Kailasnath, M.

    2015-03-30

    Strongly modulated laser emission has been observed from rhodamine B doped microring resonator embedded in a hollow polymer optical fiber by transverse optical pumping. The microring resonator is fabricated on the inner wall of a hollow polymer fiber. Highly sharp lasing lines, strong mode selection, and a collimated laser beam are observed from the fiber. Nearly single mode lasing with a side mode suppression ratio of up to 11.8 dB is obtained from the strongly modulated lasing spectrum. The microring embedded hollow polymer fiber laser has shown efficient lasing characteristics even at a propagation length of 1.5 m.

  4. Method for producing small hollow spheres

    DOEpatents

    Hendricks, Charles D. [Livermore, CA

    1979-01-09

    Method for producing small hollow spheres of glass, metal or plastic, wherein the sphere material is mixed with or contains as part of the composition a blowing agent which decomposes at high temperature (T .gtorsim. 600.degree. C). As the temperature is quickly raised, the blowing agent decomposes and the resulting gas expands from within, thus forming a hollow sphere of controllable thickness. The thus produced hollow spheres (20 to 10.sup.3 .mu.m) have a variety of application, and are particularly useful in the fabrication of targets for laser implosion such as neutron sources, laser fusion physics studies, and laser initiated fusion power plants.

  5. Method for producing small hollow spheres

    DOEpatents

    Hendricks, C.D.

    1979-01-09

    Method is disclosed for producing small hollow spheres of glass, metal or plastic, wherein the sphere material is mixed with or contains as part of the composition a blowing agent which decomposes at high temperature (T [approx gt] 600 C). As the temperature is quickly raised, the blowing agent decomposes and the resulting gas expands from within, thus forming a hollow sphere of controllable thickness. The thus produced hollow spheres (20 to 10[sup 3] [mu]m) have a variety of application, and are particularly useful in the fabrication of targets for laser implosion such as neutron sources, laser fusion physics studies, and laser initiated fusion power plants. 1 fig.

  6. Non-lead hollow point bullet

    DOEpatents

    Vaughn, Norman L.; Lowden, Richard A.

    2003-04-15

    The non-lead hollow point bullet of the instant invention comprises a mixed construction slug further comprising, a monolithic metal insert having a tapered (preferred conical) hollow point tip and a tapered (preferred conical) tail protrusion, and an unsintered powdered metal composite core in tandem alignment with the insert. The core has a hollow tapered (preferred conical) cavity tip portion coupled with the tapered (preferred conical) tail protrusion on the insert. An open tip jacket envelops at least a portion of the insert and the core. The jacket is swaged at the open tip.

  7. Impact behavior of hollow balls

    NASA Astrophysics Data System (ADS)

    Cross, Rod

    2014-03-01

    Measurements are presented of the force acting on ping-pong and squash balls impacting on a force plate. Both ball types are hollow and have the same diameter but deform in very different ways. Ping pong balls are relatively stiff and buckle inwards at high impact speeds, while squash balls are softer and tend to squash or flatten. The buckling process generates a large-amplitude, high-frequency oscillation of the force acting on a ping-pong ball. Squash balls are initially very stiff before they soften, with the result that the force on the ball rises to about half its maximum value in the first 20 μs. Ping-pong balls have a high coefficient of restitution (COR), while squash balls have a low COR. Results for both ball types are interpreted in terms of additional experimental observations.

  8. Analysis of MESSENGER high-resolution images of Mercury's hollows and implications for hollow formation

    NASA Astrophysics Data System (ADS)

    Blewett, David T.; Stadermann, Amanda C.; Susorney, Hannah C.; Ernst, Carolyn M.; Xiao, Zhiyong; Chabot, Nancy L.; Denevi, Brett W.; Murchie, Scott L.; McCubbin, Francis M.; Kinczyk, Mallory J.; Gillis-Davis, Jeffrey J.; Solomon, Sean C.

    2016-09-01

    High-resolution images from MESSENGER provide morphological information on the nature and origin of Mercury's hollows, small depressions that likely formed when a volatile constituent was lost from the surface. Because graphite may be a component of the low-reflectance material that hosts hollows, we suggest that loss of carbon by ion sputtering or conversion to methane by proton irradiation could contribute to hollows formation. Measurements of widespread hollows in 565 images with pixel scales <20 m indicate that the average depth of hollows is 24 ± 16 m. We propose that hollows cease to increase in depth when a volatile-depleted lag deposit becomes sufficiently thick to protect the underlying surface. The difficulty of developing a lag on steep topography may account for the common occurrence of hollows on crater central peaks and walls. Disruption of the lag, e.g., by secondary cratering, could restart growth of hollows in a location that had been dormant. Images at extremely high resolution (~3 m/pixel) show that the edges of hollows are straight, as expected if the margins formed by scarp retreat. These highest-resolution images reveal no superposed impact craters, implying that hollows are very young. The width of hollows within rayed crater Balanchine suggests that the maximum time for lateral growth by 1 cm is ~10,000 yr. A process other than entrainment of dust by gases evolved in a steady-state sublimation-like process is likely required to explain the high-reflectance haloes that surround many hollows.

  9. Particle Generation by Pulsed Excimer Laser Ablation in Liquid: Hollow Structures and Laser-Induced Reactions

    NASA Astrophysics Data System (ADS)

    Yan, Zijie

    2011-12-01

    Pulsed laser ablation of solid targets in liquid media is a powerful method to fabricate micro-/nanoparticles, which has attracted much interest in the past decade. It represents a combinatorial library of constituents and interactions, and one can explore disparate regions of parameter space with outcomes that are impossible to envision a priori. In this work, a pulsed excimer laser (wavelength 248 nm, pulse width 30 ns) has been used to ablate targets in liquid media with varying laser fluences, frequencies, ablation times and surfactants. It is observed that hollow particles could be fabricated by excimer laser ablation of Al, Pt, Zn, Mg, Ag, Si, TiO2, and Nb2O5 in water or aqueous solutions. The hollow particles, with sizes from tens of nanometers to micrometers, may have smooth and continuous shells or have morphologies demonstrating that they were assembled from nanoparticles. A new mechanism has been proposed to explain the formation of these novel particle geometries. They were formed on laser-produced bubbles through bubble interface pinning by laser-produced solid species. Considering the bubble dynamics, thermodynamic and kinetic requirements have been discussed in the mechanism that can explain some phenomena associated with the formation of hollow particles, especially (1) larger particles are more likely to be hollow particles; (2) Mg and Al targets have stronger tendency to generate hollow particles; and (3) the 248 nm excimer laser is more beneficial to fabricate hollow particles in water than other lasers with longer wavelengths. The work has also demonstrated the possiblities to fabricate novel nanostructures through laser-induced reactions. Zn(OH)2/dodecyl sulfate flower-like nanostructures, AgCl cubes, and Ag2O cubes, pyramids, triangular plates, pentagonal rods and bars have been obtained via reactions between laser-produced species with water, electrolyes, or surfactant molecules. The underlying mechanisms of forming these structures have been

  10. Hollow Alveolus-Like Nanovesicle Assembly with Metal-Encapsulated Hollow Zeolite Nanocrystals.

    PubMed

    Dai, Chengyi; Zhang, Anfeng; Liu, Min; Gu, Lin; Guo, Xinwen; Song, Chunshan

    2016-08-23

    Inspired by the vesicular structure of alveolus which has a porous nanovesicle structure facilitating the transport of oxygen and carbon dioxide, we designed a hollow nanovesicle assembly with metal-encapsulated hollow zeolite that would enhance diffusion of reactants/products and inhibit sintering and leaching of active metals. This zeolitic nanovesicle has been successfully synthesized by a strategy which involves a one-pot hydrothermal synthesis of hollow assembly of metal-containing solid zeolite crystals without a structural template and a selective desilication-recrystallization accompanied by leaching-hydrolysis to convert the metal-containing solid crystals into metal-encapsulated hollow crystals. We demonstrate the strategy in synthesizing a hollow nanovesicle assembly of Fe2O3-encapsulated hollow crystals of ZSM-5 zeolite. This material possesses a microporous (0.4-0.6 nm) wall of hollow crystals and a mesoporous (5-17 nm) shell of nanovesicle with macropores (about 350 nm) in the core. This hierarchical structure enables excellent Fe2O3 dispersion (3-4 nm) and resistance to sintering even at 800 °C; facilitates the transport of reactant/products; and exhibits superior activity and resistance to leaching in phenol degradation. Hollow nanovesicle assembly of Fe-Pt bimetal-encapsulated hollow ZSM-5 crystals was also prepared.

  11. Hollow Alveolus-Like Nanovesicle Assembly with Metal-Encapsulated Hollow Zeolite Nanocrystals.

    PubMed

    Dai, Chengyi; Zhang, Anfeng; Liu, Min; Gu, Lin; Guo, Xinwen; Song, Chunshan

    2016-08-23

    Inspired by the vesicular structure of alveolus which has a porous nanovesicle structure facilitating the transport of oxygen and carbon dioxide, we designed a hollow nanovesicle assembly with metal-encapsulated hollow zeolite that would enhance diffusion of reactants/products and inhibit sintering and leaching of active metals. This zeolitic nanovesicle has been successfully synthesized by a strategy which involves a one-pot hydrothermal synthesis of hollow assembly of metal-containing solid zeolite crystals without a structural template and a selective desilication-recrystallization accompanied by leaching-hydrolysis to convert the metal-containing solid crystals into metal-encapsulated hollow crystals. We demonstrate the strategy in synthesizing a hollow nanovesicle assembly of Fe2O3-encapsulated hollow crystals of ZSM-5 zeolite. This material possesses a microporous (0.4-0.6 nm) wall of hollow crystals and a mesoporous (5-17 nm) shell of nanovesicle with macropores (about 350 nm) in the core. This hierarchical structure enables excellent Fe2O3 dispersion (3-4 nm) and resistance to sintering even at 800 °C; facilitates the transport of reactant/products; and exhibits superior activity and resistance to leaching in phenol degradation. Hollow nanovesicle assembly of Fe-Pt bimetal-encapsulated hollow ZSM-5 crystals was also prepared. PMID:27429013

  12. Direct Template Approach for the Formation of (Anisotropic shape) Hollow Silicate Microparticles

    NASA Astrophysics Data System (ADS)

    Rivera Virtudazo, R. V.; Watanabe, H.; Shirai, T.; Fuji, M.; Takahashi, M.

    2011-10-01

    Non-uniform bulk or surface morphology of hollow particles has been an emerging interest because of the potential applications involving chemical storage, delivery and self-assembly for novel functional materials. There had been reports that experimental anisotropic (non-uniform) particles are much more difficult than synthesizing particles with uniform bulk and surface. Hence, this study reported a simple direct approach for the formation of unique hollow anisotropic amorphous silicate microparticles (10 to 20 μm). This was successfully prepared at room temperature via hydrolysis and condensation of tetraethylorthosilicate (TEOS), with ammonia water (NH4OH) as catalyst, ethanol (EtOH) and inorganic micro-size calcium carbonate (CaCO3) as template. The molar ratio used was 1.88:28.85:1:2.85 (CaCO3: EtOH: TEOS: NH4OH), mixed/stirred (at room temperature for 2 h), then filtered/washed by ethanol/water, after then dried and acid treated (3.0 mole/L) to obtained a micro-sized hollow SiO2 particles. This simple approach for the formation of unique anisotropic shape hollow silicate micro-sized particles can be a good alternative for a possible application as large porous carrier for nanoparticles (large drug delivery (LPP's)).

  13. Hollow polycaprolactone composite fibers for controlled magnetic responsive antifungal drug release.

    PubMed

    Wang, Baolin; Zheng, Hongxia; Chang, Ming-Wei; Ahmad, Zeeshan; Li, Jing-Song

    2016-09-01

    Hollow magnetic fibers for trigger based drug release were synthesized using one-step co-axial electrospinning (COX-ES). This was achieved by encapsulating the antifungal active 'ketoconazole' (KCZ) and iron oxide (Fe3O4) nanoparticles (NPs) in composite form within the core shell polymeric matrix material (polycaprolactone, PCL) during the COX-ES process. Dimethyl silicone oil was used as the inner core (liquid) of co-flowing solutions, which subsequently perfused out of the two-phase electrospun microstructures to form hollow fibers. Resulting drug-loaded magnetic hollow fibers were characterized using optical microscopy, scanning electron microscopy and Fourier Transform Infra-Red. The tensile strength and magnetization properties of composite fibers were also assessed. KCZ drug concentration in electrospinning solutions strongly influenced resulting fiber morphology, drug loading efficiency and release. Expedited drug release during a slow-sustained phase was demonstrated through the application of an auxiliary magnetic field. Variations in tensile strength (∼1.3-6.3MPa) were due to composite fiber components compromising polymer chain integrity. In-vitro cell studies (using human cervical carcinoma cell lines) demonstrated fiber biocompatibility. The present study demonstrates the potential application of magnetic hollow fibers for controlled treatment of fungal infections and antimicrobial indications. PMID:27295492

  14. Synthesis and characterization of Eu3+:Gd2O3 hollow spheres for biomedical applications

    NASA Astrophysics Data System (ADS)

    Kumari, Manisha; Sharma, Prashant K.

    2016-05-01

    Multifunctional magnetic Nanoparticles (MFMNPs) are potentially applicable in both drug delivery systems (DDS) and hyperthermia treatment. Structural, surface morphology and optical property were investigated by X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM) and photoluminescence (PL) measurement. Uniform Eu3+:Gd2O3 hollow microspheres of 1.8-2.0 μm diameters were synthesized by template based approach. We found that synthesized Hollow spheres are 100 nm in thickness. FE-SEM images revealed that the synthesized material are hollow in structure with good porous structure and these pores work as pathway for releasing drugs from the hollow particle inside. Luminescent properties of material were studied by room temperature photoluminescence emission spectra under the excitation of 275 nm. Material exhibit bright red emission corresponding to the 5D0-7F2 transition of the activator ions under ultraviolet light excitation, which might find potential applications in fields such as drug delivery or biological labeling because of their excellent luminescence properties.

  15. Collimation Studies with Hollow Electron Beams

    SciTech Connect

    Stancari, G.; Annala, G.; Johnson, T.R.; Saewert, G.W.; Shiltsev, V.; Still, D.A.; Valishev, A.; /Fermilab

    2011-08-01

    Recent experimental studies at the Fermilab Tevatron collider have shown that magnetically confined hollow electron beams can act as a new kind of collimator for high-intensity beams in storage rings. In a hollow electron beam collimator, electrons enclose the circulating beam. Their electric charge kicks halo particles transversely. If their distribution is axially symmetric, the beam core is unaffected. This device is complementary to conventional two-stage collimation systems: the electron beam can be placed arbitrarily close to the circulating beam; and particle removal is smooth, so that the device is a diffusion enhancer rather than a hard aperture limitation. The concept was tested in the Tevatron collider using a hollow electron gun installed in one of the existing electron lenses. We describe some of the technical aspects of hollow-beam scraping and the results of recent measurements.

  16. Hollow rhodoliths increase Svalbard's shelf biodiversity

    NASA Astrophysics Data System (ADS)

    Teichert, Sebastian

    2014-11-01

    Rhodoliths are coralline red algal assemblages that commonly occur in marine habitats from the tropics to polar latitudes. They form rigid structures of high-magnesium calcite and have a good fossil record. Here I show that rhodoliths are ecosystem engineers in a high Arctic environment that increase local biodiversity by providing habitat. Gouged by boring mussels, originally solid rhodoliths become hollow ecospheres intensely colonised by benthic organisms. In the examined shelf areas, biodiversity in rhodolith-bearing habitats is significantly greater than in habitats without rhodoliths and hollow rhodoliths yield a greater biodiversity than solid ones. This biodiversity, however, is threatened because hollow rhodoliths take a long time to form and are susceptible to global change and anthropogenic impacts such as trawl net fisheries that can destroy hollow rhodoliths. Rhodoliths and other forms of coralline red algae play a key role in a plurality of environments and need improved management and protection plans.

  17. Hollow rhodoliths increase Svalbard's shelf biodiversity.

    PubMed

    Teichert, Sebastian

    2014-11-10

    Rhodoliths are coralline red algal assemblages that commonly occur in marine habitats from the tropics to polar latitudes. They form rigid structures of high-magnesium calcite and have a good fossil record. Here I show that rhodoliths are ecosystem engineers in a high Arctic environment that increase local biodiversity by providing habitat. Gouged by boring mussels, originally solid rhodoliths become hollow ecospheres intensely colonised by benthic organisms. In the examined shelf areas, biodiversity in rhodolith-bearing habitats is significantly greater than in habitats without rhodoliths and hollow rhodoliths yield a greater biodiversity than solid ones. This biodiversity, however, is threatened because hollow rhodoliths take a long time to form and are susceptible to global change and anthropogenic impacts such as trawl net fisheries that can destroy hollow rhodoliths. Rhodoliths and other forms of coralline red algae play a key role in a plurality of environments and need improved management and protection plans.

  18. Hollow rhodoliths increase Svalbard's shelf biodiversity

    PubMed Central

    Teichert, Sebastian

    2014-01-01

    Rhodoliths are coralline red algal assemblages that commonly occur in marine habitats from the tropics to polar latitudes. They form rigid structures of high-magnesium calcite and have a good fossil record. Here I show that rhodoliths are ecosystem engineers in a high Arctic environment that increase local biodiversity by providing habitat. Gouged by boring mussels, originally solid rhodoliths become hollow ecospheres intensely colonised by benthic organisms. In the examined shelf areas, biodiversity in rhodolith-bearing habitats is significantly greater than in habitats without rhodoliths and hollow rhodoliths yield a greater biodiversity than solid ones. This biodiversity, however, is threatened because hollow rhodoliths take a long time to form and are susceptible to global change and anthropogenic impacts such as trawl net fisheries that can destroy hollow rhodoliths. Rhodoliths and other forms of coralline red algae play a key role in a plurality of environments and need improved management and protection plans. PMID:25382656

  19. Highly efficient decomposition of organic dye by aqueous-solid phase transfer and in situ photocatalysis using hierarchical copper phthalocyanine hollow spheres.

    PubMed

    Zhang, Mingyi; Shao, Changlu; Guo, Zengcai; Zhang, Zhenyi; Mu, Jingbo; Zhang, Peng; Cao, Tieping; Liu, Yichun

    2011-07-01

    The hierarchical tetranitro copper phthalocyanine (TNCuPc) hollow spheres were fabricated by a simple solvothermal method. The formation mechanism was proposed based on the evolution of morphology as a function of solvothermal time, which involved the initial formation of nanoparticles followed by their self-aggregation to microspheres and transformation into hierarchical hollow spheres by Ostwald ripening. Furthermore, the hierarchical TNCuPc hollow spheres exhibited high adsorption capacity and excellent simultaneously visible-light-driven photocatalytic performance for Rhodamine B (RB) under visible light. A possible mechanism for the "aqueous-solid phase transfer and in situ photocatalysis" was suggested. Repetitive tests showed that the hierarchical TNCuPc hollow spheres maintained high catalytic activity over several cycles, and it had a better regeneration capability under mild conditions.

  20. Liquid molded hollow cell core composite articles

    NASA Technical Reports Server (NTRS)

    Bernetich, Karl R. (Inventor)

    2005-01-01

    A hollow core composite assembly 10 is provided, including a hollow core base 12 having at least one open core surface 14, a bondable solid film 22 applied to the open core surface 14, at least one dry face ply 30 laid up dry and placed on top of the solid film 22, and a liquid resin 32 applied to the at least one dry face ply 30 and then cured.

  1. BOX-DEATH HOLLOW ROADLESS AREA, UTAH.

    USGS Publications Warehouse

    Weir, Gordon W.; Lane, Michael

    1984-01-01

    Geologic mapping, geochemical sampling, and a search for prospects and mineralized rock in the Box-Death Hollow Roadless Area, Utah indicate that there is little promise for the occurrence of mineral or energy resources in the area. Additional exploratory drilling by industry seems warranted if wells elsewhere in the region find oil or gas in strata as yet untested in the Box-Death Hollow Roadless Area.

  2. Emodin-Loaded Magnesium Silicate Hollow Nanocarriers for Anti-Angiogenesis Treatment through Inhibiting VEGF

    PubMed Central

    Ren, Hua; Zhu, Chao; Li, Zhaohui; Yang, Wei; Song, E

    2014-01-01

    The applications of anti-VEGF (vascular endothelial growth factor) treatment in ophthalmic fields to inhibit angiogenesis have been widely documented in recent years. However, the hydrophobic nature of many agents makes its delivery difficult in practice. Therefore, the aim of the present study was to introduce a new kind of hydrophobic drug carrier by employing nanoparticles with a hollow structure inside. Followed by the synthesis and characterization of magnesium silicate hollow spheres, cytotoxicity was evaluated in retina capillary endothelial cells. The loading and releasing capacity were tested by employing emodin, and the effect on VEGF expression was performed at the gene and protein level. Finally, an investigation on angiogenesis was carried on fertilized chicken eggs. The results indicated that the magnesium silicate nanoparticles had low toxicity. Emodin–MgSiO3 can inhibit the expression of both VEGF gene and protein effectively. Angiogenesis of eggs was also reduced significantly. Based on the above results, we concluded that magnesium silicate hollow spheres were good candidates as drug carriers with enough safety. PMID:25250911

  3. One-step synthesis of magnetic hollow silica and their application for nanomedicine

    NASA Astrophysics Data System (ADS)

    Wu, W.; Decoster, M. A.; Daniel, B. M.; Chen, J. F.; Yu, M. H.; Cruntu, D.; O'Connor, C. J.; Zhou, W. L.

    2006-04-01

    Magnetic nanoparticles are usually present in the form of magnetic carriers and used in nanomedicine and biosystem. In this paper, magnetic hollow silica (MHS) nanoparticles were fabricated by a one-step synthesis of Fe3O4 nanoparticles and then coating of silica on nanosized spherical calcium carbonate under alkaline conditions, in which nanosized calcium carbonate (CaCO3, 25-60 nm) was used as a scarified template, tetraethoxysilane as a precursor, and Fe3O4 nanoparticles (~5 nm), formed in the initial reaction stage, as magnetic agents. The as-synthesized nanoparticles were immersed in a weak acetic acidic solution to remove CaCO3, forming MHS carriers. The nanostructures of the MHS carriers were characterized by scanning electron microscope, transmission electron microscope, and x-ray diffraction. Superconducting quantum interference device measurement exhibited that the MHS nanoparticles were superparamagnetic. Toxicity was tested for MHS carriers using rat brain microvascular endothelial cells. The cells treated with concentration lower than 50 μg/ml of the MHS nanoparticles showed no significant toxicity. After modification by silane coupling agent, the MHS carriers have strong absorption for ibuprofen in nanomedicine field.

  4. Calix-Based Nanoparticles: A Review.

    PubMed

    Kongor, Anita R; Mehta, Viren A; Modi, Krunal M; Panchal, Manthan K; Dey, Shuvankar A; Panchal, Urvi S; Jain, Vinod K

    2016-06-01

    Calixarenes are considered as third generation supramolecules with hollow cavity-like architecture whereas nanoparticles are small entities with dimensions in the nanoscale. Many exciting achievements are seen when the calix system merges with nanoparticles which produces many fascinating facets in all fields of contemporary chemistry. The properties of nanoparticles which are tuned by calixarenes find applications in sensing, catalysis, molecular recognition, etc. Here, we have reviewed the chemistry of calix-based nanoparticles, and emphasis is laid on the modified, reducing, templated and stabilizing roles of calixarenes. This review covers the research being carried out in the domain of calix protected metal nanoparticles during last 18 years under the canopy of important 109 references. This article contains 58 figures which include 81 easy to understand structures. Calix-protected nanoparticles have enthralled researchers in the field of nanoscience with a tremendous growth in its applications, which heralds much promise to become in future a separate area of research. PMID:27573268

  5. Fabrication of cubic Zn2SnO4/SnO2 complex hollow structures and their sunlight-driven photocatalytic activity.

    PubMed

    Sun, Linqiang; Han, Xiao; Jiang, Zhe; Ye, Tingting; Li, Rong; Zhao, Xinsheng; Han, Xiguang

    2016-06-30

    Uniform hollow, yolk-shell and double-shell Zn2SnO4/SnO2 nanoparticles with cubic morphologies have been synthesized using "etching-second growth-annealed" methods. Due to the high light-harvesting efficiency and low recombination rate of the photo-generated electron-hole pair, double-shell structures of Zn2SnO4/SnO2 nanoparticles show an obvious improvement in photocatalytic activity.

  6. The Surprising in Vivo Instability of Near-IR-Absorbing Hollow Au–Ag Nanoshells

    PubMed Central

    2015-01-01

    Photothermal ablation based on resonant illumination of near-infrared-absorbing noble metal nanoparticles that have accumulated in tumors is a highly promising cancer therapy, currently in multiple clinical trials. A crucial aspect of this therapy is the nanoparticle size for optimal tumor uptake. A class of nanoparticles known as hollow Au (or Au–Ag) nanoshells (HGNS) is appealing because near-IR resonances are achievable in this system with diameters less than 100 nm. However, in this study, we report a surprising finding that in vivo HGNS are unstable, fragmenting with the Au and the remnants of the sacrificial Ag core accumulating differently in various organs. We synthesized 43, 62, and 82 nm diameter HGNS through a galvanic replacement reaction, with nanoparticles of all sizes showing virtually identical NIR resonances at ∼800 nm. A theoretical model indicated that alloying, residual Ag in the nanoparticle core, nanoparticle porosity, and surface defects all contribute to the presence of the plasmon resonance at the observed wavelength, with the major contributing factor being the residual Ag. While PEG functionalization resulted in stable nanoparticles under laser irradiation in solution, an anomalous, strongly element-specific biodistribution observed in tumor-bearing mice suggests that an avid fragmentation of all three sizes of nanoparticles occurred in vivo. Stability studies across a wide range of pH environments and in serum confirmed HGNS fragmentation. These results show that NIR resonant HGNS contain residual Ag, which does not stay contained within the HGNS in vivo. This demonstrates the importance of tracking both materials of a galvanic replacement nanoparticle in biodistribution studies and of performing thorough nanoparticle stability studies prior to any intended in vivo trial application. PMID:24547810

  7. Novel hollow α-Fe2O3 nanofibers via electrospinning for dye adsorption

    NASA Astrophysics Data System (ADS)

    Gao, Qiang; Luo, Jun; Wang, Xingyue; Gao, Chunxia; Ge, Mingqiao

    2015-04-01

    Nanomaterials such as iron oxides and ferrites have been intensively investigated for water treatment and environmental remediation applications. In this work, hollow α-Fe2O3 nanofibers made of rice-like nanorods were successfully synthesized via a simple hydrothermal reaction on polyvinyl alcohol (PVA) nanofiber template followed by calcination. The crystallographic structure and the morphology of the as-prepared α-Fe2O3 nanofibers were characterized by X-ray diffraction, energy dispersive X-ray spectrometer, and scanning electron microscope. Batch adsorption experiments were conducted, and ultraviolet-visible spectra were recorded before and after the adsorption to investigate the dye adsorption performance. The results showed that hollow α-Fe2O3 fiber assembles exhibited good magnetic responsive performance, as well as efficient adsorption for methyl orange in water. This work provided a versatile strategy for further design and development of functional nanofiber-nanoparticle composites towards various applications.

  8. Combined organic-inorganic fouling of forward osmosis hollow fiber membranes.

    PubMed

    Arkhangelsky, Elizabeth; Wicaksana, Filicia; Tang, Chuyang; Al-Rabiah, Abdulrahman A; Al-Zahrani, Saeed M; Wang, Rong

    2012-12-01

    This research focused on combined organic-inorganic fouling and cleaning studies of forward osmosis (FO) membranes. Various organic/inorganic model foulants such as sodium alginate, bovine serum albumin (BSA) and silica nanoparticles were applied to polyamide-polyethersulfone FO hollow fiber membranes fabricated in our laboratory. In order to understand all possible interactions, experiments were performed with a single foulant as well as combinations of foulants. Experimental results suggested that the degree of FO membrane fouling could be promoted by synergistic effect of organic foulants, the presence of divalent cations, low cross-flow velocity and high permeation drag force. The water flux of fouled FO hollow fibers could be fully restored by simple physical cleaning. It was also found that hydrodynamic regime played an important role in combined organic-inorganic fouling of FO membranes.

  9. Facile hydrothermal synthesis of TiO2-Bi2WO6 hollow superstructures with excellent photocatalysis and recycle properties.

    PubMed

    Hou, Ya-Fei; Liu, Shu-Juan; Zhang, Jing-huai; Cheng, Xiao; Wang, You

    2014-01-21

    One-dimensional mesoporous TiO2-Bi2WO6 hollow superstructures are prepared using a hydrothermal method and their photocatalysis and recycle properties are investigated. Experimental results indicate that anatase TiO2 nanoparticles are coupled with hierarchical Bi2WO6 hollow tubes on their surfaces. The TiO2-Bi2WO6 structure has a mesoporous wall and the pores in the wall are on average 21 nm. The hierarchical TiO2-Bi2WO6 heterostructures exhibit the highest photocatalytic activity in comparison with P25, pure Bi2WO6 hollow tube and mechanical mixture of Bi2WO6 tube and TiO2 nanoparticle in the degradation of rhodamine B (RhB) under simulated sunlight irradiation. The as-prepared TiO2-Bi2WO6 heterostructures can be easily recycled through sedimentation and they retains their high photocatalytic activity during the cycling use in the simulated sunlight-driving photodegradation process of RhB. The prepared mesoporous TiO2-Bi2WO6 with hollow superstructure is therefore a promising candidate material for water decontamination use.

  10. Jingle-bell-shaped ferrite hollow sphere with a noble metal core: Simple synthesis and their magnetic and antibacterial properties

    SciTech Connect

    Li Siheng; Wang Enbo Tian Chungui; Mao Baodong; Kang Zhenhui; Li Qiuyu; Sun Guoying

    2008-07-15

    In this paper, a simple strategy is developed for rational fabrication of a class of jingle-bell-shaped hollow structured nanomaterials marked as Ag(MFe{sub 2}O{sub 4}) (M=Ni, Co, Mg, Zn), consisting of ferrite hollow shells and metal nanoparticle cores, using highly uniform colloidal Ag(C) microspheres as template. The final composites were obtained by direct adsorption of metal cations Fe{sup 3+} and M{sup 2+} on the surface of the Ag(C) spheres followed by calcination process to remove the middle carbon shell and transform the metal ions into pure phase ferrites. The as-prepared composites were characterized by X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray analysis (EDX), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis spectroscopy and SQUID magnetometer. The results showed that the composites possess the magnetic property of the ferrite shell and the optical together with antibacterial property of the Ag core. - Graphical abstract: MFe{sub 2}O{sub 4} (M=Ni, Co, Mg, Zn) hollow spheres with a noble metal nanoparticle core were successfully prepared by using colloidal metal(C) core-shell spheres as templates with no need of surface modification. The shell thickness and magnetic properties of the ferrite hollow spheres could be controlled by varying the synthetic parameters.

  11. Flexural fatigue of hollow rolling elements. [fatigue tests on hollow cylindrical bars and bearings

    NASA Technical Reports Server (NTRS)

    Bamberger, E. N.; Parker, R. J.; Dietrich, M. W.

    1976-01-01

    Hollow cylindrical bars were tested in the rolling-contact fatigue tester to determine the effects of material and outside diameter to inside diameter (OD/ID) ratios of 2.0, 1.6, 1.4, and 1.2 on fatigue failure mode and subsequent failure propagation. The range of applied loads with these OD/ID ratios resulted in maximum tangential tensile stresses ranging from 165 to 655 megapascals (24,000 to 95,000 psi) at the bore surface. Flexural failures of the hollow test bars occurred when this bore stress was 490 megapascals (71,000 psi) or greater with AISI 52100 hollow bars and 338 megapascals (49,000 psi) or greater with AISI M-50 hollow bars. Good correlation was obtained in relating the failures of these hollow bars with flexural failures of drilled balls from previously published full scale bearing tests.

  12. Hollow glass for insulating layers

    NASA Astrophysics Data System (ADS)

    Merticaru, Andreea R.; Moagar-Poladian, Gabriel

    1999-03-01

    Common porous materials, some of which will be considered in the chapters of this book, include concrete, paper, ceramics, clays, porous semiconductors, chromotography materials, and natural materials like coral, bone, sponges, rocks and shells. Porous materials can also be reactive, such as in charcoal gasification, acid rock dissolution, catalyst deactivation and concrete. This study continues the investigations about the properties of, so-called, hollow glass. In this paper is presented a computer simulation approach in which the thermo-mechanical behavior of a 3D microstructure is directly computed. In this paper a computer modeling approach of porous glass is presented. One way to test the accuracy of the reconstructed microstructures is to computed their physical properties and compare to experimental measurement on equivalent systems. In this view, we imagine a new type of porous type of glass designed as buffer layer in multilayered printed boards in ICs. Our glass is a variable material with a variable pore size and surface area. The porosity could be tailored early from the deposition phases that permitting us to keep in a reasonable balance the dielectric constant and thermal conductivity.

  13. Magneto-plasmonic nanoparticles as theranostic platforms for magnetic resonance imaging, drug delivery and NIR hyperthermia applications.

    PubMed

    Urries, Inmaculada; Muñoz, Cristina; Gomez, Leyre; Marquina, Clara; Sebastian, Victor; Arruebo, Manuel; Santamaria, Jesus

    2014-08-01

    PEGylated magneto-plasmonic nanoparticles with a hollow or semi-hollow interior have been successfully synthesized and their physico-chemical characteristics have been investigated. The hollow interior space can be used to store drugs or other molecules of interest whereas magnetic characterization shows their potential as contrast agents in magnetic resonance imaging (MRI) applications. In addition, their plasmonic characteristics in the near infrared (NIR) region make them efficient in photothermal applications producing high temperature gradients after short irradiation times. We show that by controlling the etching conditions the inner silica shell can be selectively dissolved to achieve a hollow or semi-hollow interior without compromising the magnetic or plasmonic characteristics of the resulting nanoparticles. Magnetic measurements and transmission electron microscopy observations have been used to demonstrate the precise control during the etching process and to select an optimal concentration of the etching reagent and contact time to preserve the inner superparamagnetic iron oxide-based nanoparticles and the plasmonic properties of the constructs. Drug loading capabilities were also evaluated for both semi-hollow and as-synthesized nanoparticles using Rhodamine B isothiocyanate as a model compound. The nanoparticles produced could be potentially used as "theranostic" nanoparticles with both imaging capabilities and a dual therapeutic function (drug delivery and hyperthermia).

  14. Shell-in-Shell TiO2 hollow microspheres and optimized application in light-trapping perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Sun, Hongxia; Ruan, Peng; Bao, Zhongqiu; Chen, Lei; Zhou, Xingfu

    2015-02-01

    The shell-in-shell structured TiO2 hollow microspheres with enhanced light scattering ability were synthesized via a facile one step hydrothermal process. The diameter of the microsphere is about 1.5 μm, the core of the unique shell-in-shell structure is composed of TiO2 nanoparticles with a diameter of about 15 nm, while the shell is constructed with ∼50 nm TiO2 nanocubes. The hollow space between the outer shell and the inner shell is about 230 nm. The formation mechanism of the unique shell-in-shell structure is interpreted. The design and the optimized application of shell-in-shell structured TiO2 hollow microspheres in the light-trapping perovskite solar cells are also investigated. Owing to the light scattering properties of the shell-in-shell structure of the hollow microsphere, the optimized photoelectrode exhibits an enhanced photoelectric conversion efficiency of 4.29% using perovskite CH3NH3PbI3 as the sensitizer. The shell-in-shell hollow TiO2 microsphere shows a 21.2% increase in conversion efficiency when compared with P25 nanoparticels photoanode. The conversion efficiency enhancement is mainly attributed to the increase of short-current density induced by the light scattering effect.

  15. CO adsorption over Pd nanoparticles: A general framework for IR simulations on nanoparticles

    NASA Astrophysics Data System (ADS)

    Zeinalipour-Yazdi, Constantinos D.; Willock, David J.; Thomas, Liam; Wilson, Karen; Lee, Adam F.

    2016-04-01

    CO vibrational spectra over catalytic nanoparticles under high coverages/pressures are discussed from a DFT perspective. Hybrid B3LYP and PBE DFT calculations of CO chemisorbed over Pd4 and Pd13 nanoclusters, and a 1.1 nm Pd38 nanoparticle, have been performed in order to simulate the corresponding coverage dependent infrared (IR) absorption spectra, and hence provide a quantitative foundation for the interpretation of experimental IR spectra of CO over Pd nanocatalysts. B3LYP simulated IR intensities are used to quantify site occupation numbers through comparison with experimental DRIFTS spectra, allowing an atomistic model of CO surface coverage to be created. DFT adsorption energetics for low CO coverage (θ → 0) suggest the CO binding strength follows the order hollow > bridge > linear, even for dispersion-corrected functionals for sub-nanometre Pd nanoclusters. For a Pd38 nanoparticle, hollow and bridge-bound are energetically similar (hollow ≈ bridge > atop). It is well known that this ordering has not been found at the high coverages used experimentally, wherein atop CO has a much higher population than observed over Pd(111), confirmed by our DRIFTS spectra for Pd nanoparticles supported on a KIT-6 silica, and hence site populations were calculated through a comparison of DFT and spectroscopic data. At high CO coverage (θ = 1), all three adsorbed CO species co-exist on Pd38, and their interdiffusion is thermally feasible at STP. Under such high surface coverages, DFT predicts that bridge-bound CO chains are thermodynamically stable and isoenergetic to an entirely hollow bound Pd/CO system. The Pd38 nanoparticle undergoes a linear (3.5%), isotropic expansion with increasing CO coverage, accompanied by 63 and 30 cm- 1 blue-shifts of hollow and linear bound CO respectively.

  16. INTRACELLULAR CHEMICAL MEASUREMENTS:A GENERALIZED APPROACH WITH HIGH-SPATIAL RESOLUTION USING FUNCTIONALIZED NANOPARTICLES

    SciTech Connect

    Laurence, T

    2007-03-05

    We are developing an alternative approach to optical probes that will ultimately allow us to measure chemical concentrations in microenvironments within cells and tissues. This approach is based on monitoring the surface-enhanced Raman scattering (SERS) response of functionalized metal nanoparticles (50-100 nm in diameter). SERS allows for the sensitive detection of changes in the state of chemical groups attached to individual nanoparticles and small clusters. We present the development of a nanoscale pH meter. The pH response of these nanoprobes is tested in a cell-free medium, measuring the pH of the solution immediately surrounding the nanoparticles. We developed and used SERS correlation spectroscopy and single particle/cluster SERS spectroscopy to characterize heterogeneities in the SERS signal, which result from the formation of small nanoparticle clusters. These heterogeneities have historically provided inconsistent response to pH, leading a poor sensitivity of {approx}1 pH unit. The response of the nanoscale pH meters is tested under a wide range of conditions to approach the complex environment encountered inside living cells and to optimize probe performance. We have also developed a rapid scanning technique to obtain pH information using confocal microscopic imaging. Together with the development of hollow gold nanoshells with collaborators, this project enables future cell-based studies of pH using SERS. This research will be continued as a collaboration with the Center for Biophotonics Science and Technology (CBST) at UC Davis Medical Center.

  17. Lactobacillusassisted synthesis of titanium nanoparticles

    PubMed Central

    2007-01-01

    An eco-friendlylactobacillussp. (microbe) assisted synthesis of titanium nanoparticles is reported. The synthesis is performed at room temperature. X-ray and transmission electron microscopy analyses are performed to ascertain the formation of Ti nanoparticles. Individual nanoparticles as well as a number of aggregates almost spherical in shape having a size of 40–60 nm are found.

  18. Hollow silica-copper-carbon anodes using copper metal-organic frameworks as skeletons

    NASA Astrophysics Data System (ADS)

    Sun, Zixu; Xin, Fengxia; Cao, Can; Zhao, Chongchong; Shen, Cai; Han, Wei-Qiang

    2015-12-01

    Hollow silica-copper-carbon (H-SCC) nanocomposites are first synthesized using copper metal-organic frameworks as skeletons to form Cu-MOF@SiO2 and then subjected to heat treatment. In the composites, the hollow structure and the void space from the collapse of the MOF skeleton can accommodate the huge volume change, buffer the mechanical stress caused by lithium ion insertion/extraction and maintain the structural integrity of the electrode and a long cycling stability. The ultrafine copper with a uniform size of around 5 nm and carbon with homogeneous distribution from the decomposition of the MOF skeleton can not only enhance the electrical conductivity of the composite and preserve the structural and interfacial stabilization, but also suppress the aggregation of silica nanoparticles and cushion the volume change. In consequence, the resulting material as an anode for lithium-ion batteries (LIBs) delivers a reversible capacity of 495 mA h g-1 after 400 cycles at a current density of 500 mA g-1. The synthetic method presented in this paper provides a facile and low-cost strategy for the large-scale production of hollow silica/copper/carbon nanocomposites as an anode in LIBs.Hollow silica-copper-carbon (H-SCC) nanocomposites are first synthesized using copper metal-organic frameworks as skeletons to form Cu-MOF@SiO2 and then subjected to heat treatment. In the composites, the hollow structure and the void space from the collapse of the MOF skeleton can accommodate the huge volume change, buffer the mechanical stress caused by lithium ion insertion/extraction and maintain the structural integrity of the electrode and a long cycling stability. The ultrafine copper with a uniform size of around 5 nm and carbon with homogeneous distribution from the decomposition of the MOF skeleton can not only enhance the electrical conductivity of the composite and preserve the structural and interfacial stabilization, but also suppress the aggregation of silica nanoparticles and

  19. Nucleation engineered growth/formation of core-shell and hollow metal nanostructures

    NASA Astrophysics Data System (ADS)

    Nehra, Kamalesh; Verma, Manoj; Kumar, P. Senthil

    2016-05-01

    Herein, we present a simple yet versatile single step aqueous synthesis procedure for precisely controlling the formation of hollow as well as core-shell metal nanostructures. Modern refined Turkevich protocol has been effectively utilized so as to mechanistically understand the step-by-step autocatalytic process in the monodisperse synthesis of such exotic shaped metal nanostructures. Au core with Ag shell nanoparticles were optimized by the careful addition of Ag+ ions to the pristine gold nanoparticles, the negative charge on which efficiently attracts the Ag+-cations towards their surface and simultaneously reducing them, thereby consolidating the thin shell formation with ease. The shell thickness could as well be tuned by either changing the metal seed or cation concentration. Hollow Au nanostructures were obtained by the inverse addition of Au3+-anions to the as-prepared Ag nanoparticles, thus initiating the galvanic replacement process, wherein the concurrent oxidation of Ag0 and reduction of Au3+ takes place in a cohesive manner, resulting in the final etched nanoring / porous like morphology. The structure-property functional relationship of these artificial metal nanostructures were systematically studied utilizing optical absorption and microscopy techniques.

  20. Method for the production of fabricated hollow microspheroids

    DOEpatents

    Wickramanayake, Shan; Luebke, David R.

    2015-06-09

    The method relates to the fabrication of a polymer microspheres comprised of an asymmetric layer surrounding a hollow interior. The fabricated hollow microsphere is generated from a nascent hollow microsphere comprised of an inner core of core fluid surrounded by a dope layer of polymer dope, where the thickness of the dope layer is at least 10% and less than 50% of the diameter of the inner core. The nascent hollow microsphere is exposed to a gaseous environment, generating a vitrified hollow microsphere, which is subsequently immersed in a coagulation bath. Solvent exchange produces a fabricated hollow microsphere comprised of a densified outer skin surrounding a macroporous inner layer, which surrounds a hollow interior. In an embodiment, the polymer is a polyimide or a polyamide-imide, and the non-solvent in the core fluid and the coagulation bath is water. The fabricated hollow microspheres are particularly suited as solvent supports for gas separation processes.

  1. Tin-wall hollow ceramic spheres from slurries. Final report

    SciTech Connect

    Chapman, A.T.; Cochran, J.K.

    1992-12-31

    The overall objective of this effort was to develop a process for economically fabricating thin-wall hollow ceramic spheres from conventional ceramic powders using dispersions. This process resulted in successful production of monosized spheres in the mm size range which were point contact bonded into foams. Thin-wall hollow ceramic spheres of small (one to five millimeter) diameter have novel applications as high-temperature insulation and light structural materials when bonded into monolithic foams. During Phase 1 of this program the objective as to develop a process for fabricating thin-wall hollow spheres from powder slurries using the coaxial nozzle fabrication method. Based on the success during Phase 1, Phase 2 was revised to emphasize the assessment of the potential structural and insulation applications for the spheres and modeling of the sphere formation process was initiated. As more understanding developed, it was clear that to achieve successful structural application, the spheres had to be bonded into monolithic foams and the effort was further expanded to include both bonding into structures and finite element mechanical modeling which became the basis of Phase 3. Successful bonding techniques and mechanical modeling resulted but thermal conductivities were higher than desired for insulating activities. In addition, considerable interest had been express by industry for the technology. Thus the final Phase 4 concentrated on methods to reduce thermal conductivity by a variety of techniques and technology transfer through individualized visits. This program resulted in three Ph.D. theses and 10 M.S. theses and they are listed in the appropriate technical sections.

  2. Novel hollow mesoporous 1D TiO2 nanofibers as photovoltaic and photocatalytic materials.

    PubMed

    Zhang, Xiang; Thavasi, Velmurugan; Mhaisalkar, S G; Ramakrishna, Seeram

    2012-03-01

    Hollow mesoporous one dimensional (1D) TiO(2) nanofibers are successfully prepared by co-axial electrospinning of a titanium tetraisopropoxide (TTIP) solution with two immiscible polymers; polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP) using a core-shell spinneret, followed by annealing at 450 °C. The annealed mesoporous TiO(2) nanofibers are found to having a hollow structure with an average diameter of 130 nm. Measurements using the Brunauer-Emmett-Teller (BET) method reveal that hollow mesoporous TiO(2) nanofibers possess a high surface area of 118 m(2) g(-1) with two types of mesopores; 3.2 nm and 5.4 nm that resulted from gaseous removal of PEO and PVP respectively during annealing. With hollow mesoporous TiO(2) nanofibers as the photoelectrode in dye sensitized solar cells (DSSC), the solar-to-current conversion efficiency (η) and short circuit current (J(sc)) are measured as 5.6% and 10.38 mA cm(-2) respectively, which are higher than those of DSSC made using regular TiO(2) nanofibers under identical conditions (η = 4.2%, J(sc) = 8.99 mA cm(-2)). The improvement in the conversion efficiency is mainly attributed to the higher surface area and mesoporous TiO(2) nanostructure. It facilitates the adsorption of more dye molecules and also promotes the incident photon to electron conversion. Hollow mesoporous TiO(2) nanofibers with close packing of grains and crystals intergrown with each other demonstrate faster electron diffusion, and longer electron recombination time than regular TiO(2) nanofibers as well as P25 nanoparticles. The surface effect of hollow mesoporous TiO(2) nanofibers as a photocatalyst for the degradation of rhodamine dye was also investigated. The kinetic study shows that the hollow mesoporous surface of the TiO(2) nanofibers influenced its interactions with the dye, and resulted in an increased catalytic activity over P25 TiO(2) nanocatalysts. PMID:22315140

  3. Ultrasmall hollow gold-silver nanoshells with extinctions strongly red-shifted to the near-infrared.

    PubMed

    Vongsavat, Varadee; Vittur, Brandon M; Bryan, William W; Kim, Jun-Hyun; Lee, T Randall

    2011-09-01

    Hollow gold-silver nanoshells having systematically varying sizes between 40 and 100 nm were prepared. These particles consist of a hollow spherical silver shell surrounded by a thin gold layer. By varying the volume of the gold stock solution added to suspensions of small silver-core templates, we tailored the hollow gold-silver nanoshells to possess strong tunable optical extinctions that range from the visible to the near-IR spectral regions, with extinctions routinely centered at ∼950 nm. The size and morphology of these core/shell nanoparticles were characterized by dynamic light scattering (DLS), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). Separately, X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were used for measuring their elemental composition; UV-vis spectroscopy was used to evaluate their optical properties. Given their relatively small size compared to other nanoparticles that absorb strongly at near IR wavelengths, these easy-to-synthesize particles should find use in applications that require ultrasmall nanoparticles with extinctions comfortably beyond visible wavelengths (e.g., medicinal therapies, diagnostic imaging, nanofluidics, and display technologies). PMID:21761855

  4. Method of making a non-lead hollow point bullet

    DOEpatents

    Vaughn, Norman L.; Lowden, Richard A.

    2003-10-07

    The method of making a non-lead hollow point bullet has the steps of a) compressing an unsintered powdered metal composite core into a jacket, b) punching a hollow cavity tip portion into the core, c) seating an insert, the insert having a hollow point tip and a tail protrusion, on top of the core such that the tail protrusion couples with the hollow cavity tip portion, and d) swaging the open tip of the jacket.

  5. Temperature Distributions in Hollow Cathode Emitters

    NASA Technical Reports Server (NTRS)

    Polk, Jay; Marrese, Colleen; Thornber, Ben; Dang, Lisa; Johnson, Lee

    2004-01-01

    Life-limiting processes in hollow cathodes are determined largely by the temperature of the emitter. To support development of cathode life models we have developed a noncontact temperature measurement technique which employs a stepper motor-driven fiber optic probe. The probe is driven inside the hollow cathode and collects light radiated by the hot interior surface of the emitter. Ratio pyrometry is used determine the axial temperature profile. Thermocouples on the orifice plate provide measurements ofthe external temperature during cathode operation and are used to calibrate the pyrometer system in situ with a small oven enclosing the externally heated cathode. Initial measurements of the temperature distribution in a hollow cathode with the same geometry as a cathode that failed after operating at 12 A emission current for 27800 hours are discussed.

  6. Pine Hollow Watershed Project : FY 2000 Projects.

    SciTech Connect

    Sherman County Soil and Water Conservation District

    2001-06-01

    The Pine Hollow Project (1999-010-00) is an on-going watershed restoration effort administered by Sherman County Soil and Water Conservation District and spearheaded by Pine Hollow/Jackknife Watershed Council. The headwaters are located near Shaniko in Wasco County, and the mouth is in Sherman County on the John Day River. Pine Hollow provides more than 20 miles of potential summer steelhead spawning and rearing habitat. The watershed is 92,000 acres. Land use is mostly range, with some dryland grain. There are no water rights on Pine Hollow. Due to shallow soils, the watershed is prone to rapid runoff events which scour out the streambed and the riparian vegetation. This project seeks to improve the quality of upland, riparian and in-stream habitat by restoring the natural hydrologic function of the entire watershed. Project implementation to date has consisted of construction of water/sediment control basins, gradient terraces on croplands, pasture cross-fences, upland water sources, and grass seeding on degraded sites, many of which were crop fields in the early part of the century. The project is expected to continue through about 2007. From March 2000 to June 2001, the Pine Hollow Project built 6 sediment basins, 1 cross-fence, 2 spring developments, 1 well development, 1 solar pump, 50 acres of native range seeding and 1 livestock waterline. FY2000 projects were funded by BPA, Oregon Watershed Enhancement Board, US Fish and Wildlife Service and landowners. In-kind services were provided by Sherman County Soil and Water Conservation District, USDA Natural Resources Conservation Service, USDI Bureau of Land Management, Oregon Department of Fish and Wildlife, Pine Hollow/Jackknife Watershed Council, landowners and Wasco County Soil and Water Conservation District.

  7. Hollow needle used to cut metal honeycomb structures

    NASA Technical Reports Server (NTRS)

    Gregg, E. A.

    1966-01-01

    Hollow needle tool cuts metal honeycomb structures without damaging adjacent material. The hollow needle combines an electrostatic discharge and a stream of oxygen at a common point to effect rapid, accurate metal cutting. The tool design can be varied to use the hollow needle principle for cutting a variety of shapes.

  8. Mass balancing of hollow fan blades

    NASA Technical Reports Server (NTRS)

    Kielb, R. E.

    1986-01-01

    A typical section model is used to analytically investigate the effect of mass balancing as applied to hollow, supersonic fan blades. A procedure to determine the best configuration of an internal balancing mass to provide flutter alleviation is developed. This procedure is applied to a typical supersonic shroudless fan blade which is unstable in both the solid configuration and when it is hollow with no balancing mass. The addition of an optimized balancing mass is shown to stabilize the blade at the design condition.

  9. Microfabricated hollow microneedle array using ICP etcher

    NASA Astrophysics Data System (ADS)

    Ji, Jing; Tay, Francis E. H.; Miao, Jianmin

    2006-04-01

    This paper presents a developed process for fabrication of hollow silicon microneedle arrays. The inner hollow hole and the fluidic reservoir are fabricated in deep reactive ion etching. The profile of outside needles is achieved by the developed fabrication process, which combined isotropic etching and anisotropic etching with inductively coupled plasma (ICP) etcher. Using the combination of SF6/O2 isotropic etching chemistry and Bosch process, the high aspect ratio 3D and high density microneedle arrays are fabricated. The generated needle external geometry can be controlled by etching variables in the isotropic and anisotropic cases.

  10. Mesoporous hollow spheres from soap bubbling.

    PubMed

    Yu, Xianglin; Liang, Fuxin; Liu, Jiguang; Lu, Yunfeng; Yang, Zhenzhong

    2012-02-01

    The smaller and more stable bubbles can be generated from the large parent bubbles by rupture. In the presence of a bubble blowing agent, hollow spheres can be prepared by bubbling a silica sol. Herein, the trapped gas inside the bubble acts as a template. When the porogen, i.e., other surfactant, is introduced, a mesostructured shell forms by the co-assembly with the silica sol during sol-gel process. Morphological evolution emphasizes the prerequisite of an intermediate interior gas flow rate and high exterior gas flow rate for hollow spheres. The method is valid for many compositions from inorganic, polymer to their composites. PMID:22078340

  11. Mesoporous hollow spheres from soap bubbling.

    PubMed

    Yu, Xianglin; Liang, Fuxin; Liu, Jiguang; Lu, Yunfeng; Yang, Zhenzhong

    2012-02-01

    The smaller and more stable bubbles can be generated from the large parent bubbles by rupture. In the presence of a bubble blowing agent, hollow spheres can be prepared by bubbling a silica sol. Herein, the trapped gas inside the bubble acts as a template. When the porogen, i.e., other surfactant, is introduced, a mesostructured shell forms by the co-assembly with the silica sol during sol-gel process. Morphological evolution emphasizes the prerequisite of an intermediate interior gas flow rate and high exterior gas flow rate for hollow spheres. The method is valid for many compositions from inorganic, polymer to their composites.

  12. Stabilized Hollow Ions Extracted in Vacuum

    SciTech Connect

    Ninomiya, S.; Yamazaki, Y.; Azuma, T.; Komaki, K.; Koike, F.; Masuda, H.; Kuroki, K.; Sekiguchi, M.

    1997-06-01

    K x rays emitted from 2.1 keV/uN{sup 6+} ions passed through a thin Ni microcapillary foil were measured in coincidence with the exit charge states. Ions with a K hole but with several electrons in outershells, i.e., hollow ions formed above a surface (in the first generation), were successfully extracted in vacuum. It was found that a considerable fraction of extracted hollow ions had extremely long lifetimes of the order of ns. {copyright} {ital 1997} {ital The American Physical Society}

  13. Pulsed hollow cathode discharge with nanosecond risetime

    SciTech Connect

    Schaefer, G.; Husoy, P.O.; Schoenbach, K.H.

    1984-12-01

    This paper reports the operation of a cylindrical hollow cathode discharge with current risetimes of a few nanoseconds at current densities at the entrance of the cathode in the range of 50-560A x cm/sup -2/ and at voltages of 280-850 V. Time-dependent measurements of the impedance of the discharge are presented. They allow for the evaluation of discharge quantities such as risetime, delay time, discharge voltage, and current, depending on the operation parameters as applied voltage, pressure, and preionization. The power density in the active region of the hollow cathode exceeded 200 kW x cm/sup -3/.

  14. Hollow superparamagnetic PLGA/Fe 3O 4 composite microspheres for lysozyme adsorption

    NASA Astrophysics Data System (ADS)

    Yang, Qi; Wu, Yao; Lan, Fang; Ma, Shaohua; Xie, Liqin; He, Bin; Gu, Zhongwei

    2014-02-01

    Uniform hollow superparamagnetic poly(lactic-co-glycolic acid) (PLGA)/Fe3O4 composite microspheres composed of an inner cavity, PLGA inner shell and Fe3O4 outer shell have been synthesized by a modified oil-in-water (O/W) emulsion-solvent evaporation method using Fe3O4 nanoparticles as a particulate emulsifier. The obtained composite microspheres with an average diameter of 2.5 μm showed excellent monodispersity and stability in aqueous medium, strong magnetic responsiveness, high magnetite content (>68%), high saturation magnetization (58 emu g-1) and high efficiency in lysozyme adsorption.

  15. Hollow superparamagnetic PLGA/Fe3O4 composite microspheres for lysozyme adsorption.

    PubMed

    Yang, Qi; Wu, Yao; Lan, Fang; Ma, Shaohua; Xie, Liqin; He, Bin; Gu, Zhongwei

    2014-02-28

    Uniform hollow superparamagnetic poly(lactic-co-glycolic acid) (PLGA)/Fe(3)O(4) composite microspheres composed of an inner cavity, PLGA inner shell and Fe(3)O(4) outer shell have been synthesized by a modified oil-in-water (O/W) emulsion-solvent evaporation method using Fe(3)O(4) nanoparticles as a particulate emulsifier. The obtained composite microspheres with an average diameter of 2.5 μm showed excellent monodispersity and stability in aqueous medium, strong magnetic responsiveness, high magnetite content (>68%), high saturation magnetization (58 emu g(-1)) and high efficiency in lysozyme adsorption. PMID:24492410

  16. Electrostatic Assembly of Sandwich-like Ag-C@ZnO-C@Ag-C Hybrid Hollow Microspheres with Excellent High-Rate Lithium Storage Properties.

    PubMed

    Xie, Qingshui; Ma, Yating; Wang, Xuanpeng; Zeng, Deqian; Wang, Laisen; Mai, Liqiang; Peng, Dong-Liang

    2016-01-26

    Herein, we introduce a facile electrostatic attraction approach to produce zinc-silver citrate hollow microspheres, followed by thermal heating treatment in argon to ingeniously synthesize sandwich-like Ag-C@ZnO-C@Ag-C hybrid hollow microspheres. The 3D carbon conductive framework in the hybrids derives from the in situ carbonation of carboxylate acid groups in zinc-silver citrate hollow microspheres during heating treatment, and the continuous and homogeneous Ag nanoparticles on the outer and inner surfaces of hybrid hollow microspheres endow the shells with the sandwiched configuration (Ag-C@ZnO-C@Ag-C). When applied as the anode materials for lithium ion batteries, the fabricated hybrid hollow microspheres with sandwich-like shells reveal a very large reversible capacity of 1670 mAh g(-1) after 200 cycles at a current density of 0.2 A g(-1). Even at the very large current densities of 1.6 and 10.0 A g(-1), the high specific capacities of about 1063 and 526 mAh g(-1) can be retained, respectively. The greatly enhanced electrochemical properties of Ag-C@ZnO-C@Ag-C hybrid microspheres are attributed to their special structural features such as the hollow structures, the sandwich-like shells, and the nanometer-sized building blocks.

  17. Core-decomposition-facilitated fabrication of hollow rare-earth silicate nanowalnuts from core-shell structures via the Kirkendall effect.

    PubMed

    Zhou, Wenli; Zou, Rui; Yang, Xianfeng; Huang, Ningyu; Huang, Junjian; Liang, Hongbin; Wang, Jing

    2015-08-28

    Hollow micro-/nanostructures have been widely applied in the fields of lithium ion batteries, catalysis, biosensing, biomedicine, and so forth. The Kirkendall effect, which involves a non-equilibrium mutual diffusion process, is one of many important fabrication strategies for the formation of hollow nanomaterials. Accordingly, full understanding of the interdiffusion process at the nanoscale is very important for the development of novel multifunctional hollow materials. In this work, hollow Y2SiO5 nanowalnuts have been fabricated from the conversion of YOHCO3@SiO2 core-shell nanospheres via the Kirkendall effect. More importantly, it was found that in the conversion process, the decomposition of YOHCO3 core imposes on the formation of the Y2SiO5 interlayer by facilitating the initial nucleation of the Kirkendall nanovoids and accelerating the interfacial diffusion of Y2O3@SiO2 core@shell. The simple concept developed herein can be employed as a general Kirkendall effect strategy without the assistance of any catalytically active Pt nanocrystals or gold motion for future fabrication of novel hollow nanostructures. Moreover, the photoluminescence properties of rare-earth ion doped hollow Y2SiO5 nanoparticles are researched.

  18. Microwave-assisted hydrothermal synthesis of Cu/Cu2O hollow spheres with enhanced photocatalytic and gas sensing activities at room temperature.

    PubMed

    Zou, Xinwei; Fan, Huiqing; Tian, Yuming; Zhang, Mingang; Yan, Xiaoyan

    2015-05-01

    Cu/Cu2O nano-heterostructure hollow spheres with a submicron diameter (200-500 nm) were prepared by a microwave-assisted hydrothermal method using Cu(OAc)2·H2O, PVP and ascorbic acid solution as the precursors. The morphology of the products could evolve with the hydrothermal time from solid spheres to thick-shell hollow spheres, then to thin-shell hollow spheres, and finally to nanoparticles. Moreover, the content of Cu in the products could be controlled by adjusting the hydrothermal time. The spontaneous forming of the hollow structure spheres was found to result from the Ostwald ripening effect during the low temperature (100 °C) hydrothermal reaction process. The photocatalytic degradation activities on MO under visible-light irradiation and the gas sensing activities toward the oxidizing NO2 gas of different Cu/Cu2O nano-heterostructure hollow spheres were investigated. As a result, the Cu/Cu2O nano-heterostructure hollow spheres obtained at the hydrothermal time of 30 min, with a rough/porous thin-shell structure and a Cu content of about 10.5 wt%, exhibited the best photocatalytic and gas sensing performances compared with others.

  19. Hollow circular-truncated cone resonator and its hollow variable biconical laser beam

    NASA Astrophysics Data System (ADS)

    Liu, Jinglun; Chen, Mei; Wang, Qionghua; Sun, Nianchun

    2014-05-01

    To obtain a hollow variable biconical laser beam (HVBLB), a CO2 laser having a hollow circular-truncated cone resonator (HCTCR) is presented. This HCTCR comprises a rotationally symmetric total-reflecting concave mirror at the bottom, a rotationally symmetric part-reflecting convex mirror at the top, and a hollow circular-truncated cone discharge tube at the middle. The cross section of this generated biconical laser beam changes from annulus to circular to annulus and the size of this cross section from big to small to large as the propagation distance increases. So, a kind of laser beam with variable center intensity from zero to peak value to zero is obtained and is known as HVBLB. Due to the inclusion of part of the hollow laser beam (HLB) and solid laser beam, this HVBLB requires no additional beam-shaping element and has broad applications such as optical trapping and commercial manufacturing.

  20. Facile synthesis and intraparticle self-catalytic oxidation of dextran-coated hollow Au-Ag nanoshell and its application for chemo-thermotherapy.

    PubMed

    Jang, Hongje; Kim, Young-Kwan; Huh, Hyun; Min, Dal-Hee

    2014-01-28

    Galvanic replacement reaction is a useful method to prepare various hollow nanostructures. We developed fast and facile preparation of biocompatible and structurally robust hollow Au-Ag nanostructures by using dextran-coated Ag nanoparticles. Oxidation of the surface dextran alcohols was enabled by catalytic activity of the core Au-Ag nanostructure, introducing carbonyl groups that are useful for further bioconjugation. Subsequent doxorubicin (Dox) conjugation via Schiff base formation was achieved, giving high payload of approximately 35 000 Dox per particle. Near-infrared-mediated photothermal conversion showed high efficacy of the Dox-loaded Au-Ag nanoshell as a combinational chemo-thermotherapy to treat cancer cells.

  1. Method for preparing hollow metal oxide microsphere

    DOEpatents

    Schmitt, C.R.

    1974-02-12

    Hollow refractory metal oxide microspheres are prepared by impregnating resinous microspheres with a metallic compound, drying the impregnated microspheres, heating the microspheres slowly to carbonize the resin, and igniting the microspheres to remove the carbon and to produce the metal oxide. Zirconium oxide is given as an example. (Official Gazette)

  2. The Hollow Men: A Cautionary Tale.

    ERIC Educational Resources Information Center

    Fruman, Norman

    1991-01-01

    A review of Charles Sykes' book "The Hollow Men: Politics and Corruption in Higher Education" focuses on the portion that chronicles the political history of Dartmouth College (New Hampshire) from 1769. It is found to be a comprehensive analysis of the college's decline resulting from a "radically politicized and self-regarding" faculty. (MSE)

  3. Growth of hollow nickel fluoride whiskers

    SciTech Connect

    Petrov, S. V.; Orekhov, Yu. F.; Fedorov, P. P.

    2009-07-15

    Hollow nickel fluoride whiskers have been obtained by condensation from the vapor phase onto a platinum substrate in a flow of hydrogen fluoride. Crystals up to 5 mm in length have a square cross section with a 300 {+-} 30-{mu}m side. The wall thickness is 85 {+-} 20 {mu}m.

  4. From Nanofibrous Hollow Microspheres to Nanofibrous Hollow Discs and Nanofibrous Shells.

    PubMed

    Zhang, Zhanpeng; Ma, Peter X

    2015-10-01

    Nano- and microsized structures are of central importance to advanced materials and nanotechnologies, which have tremendously impacted both biomedical and physical sciences. Herein, novel emulsification and thermally induced phase separation (TIPS) techniques to fabricate linear polymers into nanofibrous hollow objects are reported for the first time. Through manipulating the emulsification conditions, the evolution of the emulsion structure can be controlled and nanofibrous hollow microspheres with a controllable opening size and nano-fibrous shells can be fabricated. Through adjusting the rheological properties of the emulsions, nanofibrous hollow discs are also created. A new mechanistic hypotheses of the nanofibrous hollow object formation is proposed: the nano- and microscaled structures are independently determined by TIPS and the emulsification process, respectively. Guided by this theory, the nanofiber formation conditions for two further additional polymers (polyacrylonitrile and Nylon) under TIPS are identified, and solid/nanofibrous non-hollow/hollow microspheres are created from these two additional polymers under TIPS and emulsification for the first time. Therefore, the developed strategy is applicable to various polymer systems, and can broadly impact nano- and microfabrication technologies.

  5. Facile Synthesis of Magnetic Mesoporous Hollow Carbon Microspheres for Rapid Capture of Low-Concentration Peptides

    PubMed Central

    2015-01-01

    Mesoporous and hollow carbon microspheres embedded with magnetic nanoparticles (denoted as MHM) were prepared via a facile self-sacrificial method for rapid capture of low-abundant peptides from complex biological samples. The morphology, structure, surface property, and magnetism were well-characterized. The hollow magnetic carbon microspheres have a saturation magnetization value of 130.2 emu g–1 at room temperature and a Brunauer–Emmett–Teller specific surface area of 48.8 m2 g–1 with an average pore size of 9.2 nm for the mesoporous carbon shell. The effectiveness of these MHM affinity microspheres for capture of low-concentration peptides was evaluated by standard peptides, complex protein digests, and real biological samples. These multifunctional hollow carbon microspheres can realize rapid capture and convenient separation of low-concentration peptides. They were validated to have better performance than magnetic mesoporous silica and commercial peptide-enrichment products. In addition, they can be easily recycled and present excellent reusability. Therefore, it is expected that this work may provide a promising tool for high-throughput discovery of peptide biomarkers from biological samples for disease diagnosis and other biomedical applications. PMID:24992375

  6. Facile synthesis of magnetic mesoporous hollow carbon microspheres for rapid capture of low-concentration peptides.

    PubMed

    Cheng, Gong; Zhou, Ming-Da; Zheng, Si-Yang

    2014-08-13

    Mesoporous and hollow carbon microspheres embedded with magnetic nanoparticles (denoted as MHM) were prepared via a facile self-sacrificial method for rapid capture of low-abundant peptides from complex biological samples. The morphology, structure, surface property, and magnetism were well-characterized. The hollow magnetic carbon microspheres have a saturation magnetization value of 130.2 emu g(-1) at room temperature and a Brunauer-Emmett-Teller specific surface area of 48.8 m(2) g(-1) with an average pore size of 9.2 nm for the mesoporous carbon shell. The effectiveness of these MHM affinity microspheres for capture of low-concentration peptides was evaluated by standard peptides, complex protein digests, and real biological samples. These multifunctional hollow carbon microspheres can realize rapid capture and convenient separation of low-concentration peptides. They were validated to have better performance than magnetic mesoporous silica and commercial peptide-enrichment products. In addition, they can be easily recycled and present excellent reusability. Therefore, it is expected that this work may provide a promising tool for high-throughput discovery of peptide biomarkers from biological samples for disease diagnosis and other biomedical applications. PMID:24992375

  7. Hollow silica-copper-carbon anodes using copper metal-organic frameworks as skeletons.

    PubMed

    Sun, Zixu; Xin, Fengxia; Cao, Can; Zhao, Chongchong; Shen, Cai; Han, Wei-Qiang

    2015-12-28

    Hollow silica-copper-carbon (H-SCC) nanocomposites are first synthesized using copper metal-organic frameworks as skeletons to form Cu-MOF@SiO(2) and then subjected to heat treatment. In the composites, the hollow structure and the void space from the collapse of the MOF skeleton can accommodate the huge volume change, buffer the mechanical stress caused by lithium ion insertion/extraction and maintain the structural integrity of the electrode and a long cycling stability. The ultrafine copper with a uniform size of around 5 nm and carbon with homogeneous distribution from the decomposition of the MOF skeleton can not only enhance the electrical conductivity of the composite and preserve the structural and interfacial stabilization, but also suppress the aggregation of silica nanoparticles and cushion the volume change. In consequence, the resulting material as an anode for lithium-ion batteries (LIBs) delivers a reversible capacity of 495 mA h g(-1) after 400 cycles at a current density of 500 mA g(-1). The synthetic method presented in this paper provides a facile and low-cost strategy for the large-scale production of hollow silica/copper/carbon nanocomposites as an anode in LIBs. PMID:26489524

  8. Facile synthesis of magnetic mesoporous hollow carbon microspheres for rapid capture of low-concentration peptides.

    PubMed

    Cheng, Gong; Zhou, Ming-Da; Zheng, Si-Yang

    2014-08-13

    Mesoporous and hollow carbon microspheres embedded with magnetic nanoparticles (denoted as MHM) were prepared via a facile self-sacrificial method for rapid capture of low-abundant peptides from complex biological samples. The morphology, structure, surface property, and magnetism were well-characterized. The hollow magnetic carbon microspheres have a saturation magnetization value of 130.2 emu g(-1) at room temperature and a Brunauer-Emmett-Teller specific surface area of 48.8 m(2) g(-1) with an average pore size of 9.2 nm for the mesoporous carbon shell. The effectiveness of these MHM affinity microspheres for capture of low-concentration peptides was evaluated by standard peptides, complex protein digests, and real biological samples. These multifunctional hollow carbon microspheres can realize rapid capture and convenient separation of low-concentration peptides. They were validated to have better performance than magnetic mesoporous silica and commercial peptide-enrichment products. In addition, they can be easily recycled and present excellent reusability. Therefore, it is expected that this work may provide a promising tool for high-throughput discovery of peptide biomarkers from biological samples for disease diagnosis and other biomedical applications.

  9. Ultrasmall, well-dispersed, hollow siliceous spheres with enhanced endocytosis properties.

    PubMed

    Zhu, Jie; Tang, Jiawei; Zhao, Lingzhi; Zhou, Xufeng; Wang, Yunhua; Yu, Chengzhong

    2010-01-01

    The synthesis of ultrasmall, well-dispersed, hollow siliceous spheres (HSSs) by using a block copolymer as the template and tetraethoxysilane as a silica source under acidic conditions is reported. After removing the surfactant core of as-synthesized, spherical, silica-coated block-copolymer micelles, HSSs with a uniform particle size of 24.7 nm, a cavity diameter of 11.7 nm, and a wall thickness of 6.5 nm are obtained. It is shown that by surface functionalization of HSSs with methyl groups during synthesis, HSSs can be further dispersed in solvents such as water or ethanol to form a stable sol. Moreover, the hollow cavities are accessible for further loading of functional components. In addition, it is demonstrated that HSSs possess superior endocytosis properties for HeLa cells compared to those of conventional mesoporous silica nanoparticles. A feasible and designable strategy for synthesizing novel well-dispersed hollow structures with ultrasmall diameters instead of conventional ordered mesostructures is provided. It is expected that HSSs may find broad applications in bionanotechnology, such as drug carriers, cell imaging, and targeted therapy.

  10. Pearling of lipid vesicles induced by nanoparticles.

    PubMed

    Yu, Yan; Granick, Steve

    2009-10-14

    We show that cationic nanoparticles encapsulated within vesicles of phosphocholine lipid can induce pearling. The dynamic process occurs as two stages: formation of tubular protrusions followed by pearling instability. The breakup into individual vesicles can be controlled by nanoparticle concentration.

  11. Novel hollow mesoporous 1D TiO2 nanofibers as photovoltaic and photocatalytic materials

    NASA Astrophysics Data System (ADS)

    Zhang, Xiang; Thavasi, Velmurugan; Mhaisalkar, S. G.; Ramakrishna, Seeram

    2012-02-01

    Hollow mesoporous one dimensional (1D) TiO2 nanofibers are successfully prepared by co-axial electrospinning of a titanium tetraisopropoxide (TTIP) solution with two immiscible polymers; polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP) using a core-shell spinneret, followed by annealing at 450 °C. The annealed mesoporous TiO2 nanofibers are found to having a hollow structure with an average diameter of 130 nm. Measurements using the Brunauer-Emmett-Teller (BET) method reveal that hollow mesoporous TiO2 nanofibers possess a high surface area of 118 m2 g-1 with two types of mesopores; 3.2 nm and 5.4 nm that resulted from gaseous removal of PEO and PVP respectively during annealing. With hollow mesoporous TiO2 nanofibers as the photoelectrode in dye sensitized solar cells (DSSC), the solar-to-current conversion efficiency (η) and short circuit current (Jsc) are measured as 5.6% and 10.38 mA cm-2 respectively, which are higher than those of DSSC made using regular TiO2 nanofibers under identical conditions (η = 4.2%, Jsc = 8.99 mA cm-2). The improvement in the conversion efficiency is mainly attributed to the higher surface area and mesoporous TiO2 nanostructure. It facilitates the adsorption of more dye molecules and also promotes the incident photon to electron conversion. Hollow mesoporous TiO2 nanofibers with close packing of grains and crystals intergrown with each other demonstrate faster electron diffusion, and longer electron recombination time than regular TiO2 nanofibers as well as P25 nanoparticles. The surface effect of hollow mesoporous TiO2 nanofibers as a photocatalyst for the degradation of rhodamine dye was also investigated. The kinetic study shows that the hollow mesoporous surface of the TiO2 nanofibers influenced its interactions with the dye, and resulted in an increased catalytic activity over P25 TiO2 nanocatalysts.Hollow mesoporous one dimensional (1D) TiO2 nanofibers are successfully prepared by co-axial electrospinning of a titanium

  12. Facile synthesis and luminescence of uniform Y2O3 hollow spheres by a sacrificial template route.

    PubMed

    Jia, Guang; You, Hongpeng; Song, Yanhua; Huang, Yeju; Yang, Mei; Zhang, Hongjie

    2010-09-01

    Uniform Y(2)O(3) hollow microspheres have been successfully prepared via a urea-based homogeneous precipitation technique with colloidal melamine formaldehyde (MF) microspheres as templates followed by a subsequent calcination process. X-ray diffraction, energy dispersive X-ray analysis, and Fourier transform infrared spectroscopy results show that the MF templates can be effectively removed, and the amorphous precursor has converted to crystalline Y(2)O(3) during the annealing process. Scanning electron microscopy and transmission electron microscopy images indicate that the Y(2)O(3) hollow spheres inherit a spherical shape and good dispersion of MF templates, and the shell of the hollow spheres is composed of a large amount of uniform nanoparticles. The lanthanide activator ion Ln(3+)-doped Y(2)O(3) hollow microspheres exhibit bright down- and upconversion luminescence with different colors coming from different activator ions under ultraviolet or 980 nm light excitation, which may find potential applications in fields such as light phosphor powders, advanced flat panel displays, or drug delivery.

  13. Long TiO2 hollow fibers with mesoporous walls: sol-gel combined electrospun fabrication and photocatalytic properties.

    PubMed

    Zhan, Sihui; Chen, Dairong; Jiao, Xiuling; Tao, Caihong

    2006-06-15

    Long TiO2 hollow fibers with mesoporous walls have been fabricated with the sol-gel combined two-capillary spinneret electrospinning technique using a triblock copolymer (Pluronic, P123, (H(C2H5O)20(C3H7O)70 (C2H5O)20OH) as a pore-directing agent. The as-prepared hollow fibers were as long as 30 cm with an outer diameter of 0.1-4 microm and wall thickness of 60-500 nm. The diameters and wall thicknesses of the hollow fibers could be tuned by adjusting the electrospinning parameters. The fiber walls were composed of mesopores 6.7 nm in diameter as calculated from the N2 adsorption/desorption isotherm. The high-resolution TEM (HR-TEM) images exhibited that the mesopores were hexagonally aligned with a low order because of the curving of the pores. When comparing with other nanostructured TiO2 materials such as commercial TiO2 nanoparticles (P25, Degussa) and mesoporous TiO2 powders, the hollow fibers exhibited higher photocatalytic activities toward degradation of methylene blue and gaseous formaldehyde.

  14. Hollow chitosan/alginate nanocapsules for bioactive compound delivery.

    PubMed

    Rivera, Melissa C; Pinheiro, Ana C; Bourbon, Ana I; Cerqueira, Miguel A; Vicente, António A

    2015-08-01

    This work aimed at the development of biodegradable nanocapsules as carriers of two bioactive compounds, 5-aminosalycilic acid and glycomacropeptide. Nanocapsules were produced through layer-by-layer (LbL) deposition of chitosan (CH) and alginate (ALG) layers on polystyrene nanoparticles. The bioactive compounds were incorporated on the third layer of the nanocapsules being its encapsulation efficiency and release behaviour evaluated. The LbL deposition process, stability, morphology and size of the multilayer nanocapsules were monitored by means of zeta potential and transmission electron microscopy (TEM). The bioactive compounds release from the CH/ALG nanocapsules was successfully described by a mathematical model (linear superimposition model - LSM), which allowed concluding that bioactive compounds release is due to both Brownian motion and the polymer relaxation of the CH/ALG layers. Final results demonstrated that the synthesized LbL hollow nanocapsules presented spherical morphology and a good capacity to encapsulate different bioactive compounds, being the best results obtained for the system containing 5-aminosalycilic acid (with an encapsulation efficiency of approximately 70%). CH/ALG multilayer nanocapsules could be a promising carrier of bioactive compounds for applications in food and pharmaceutical industries.

  15. Rice-like hollow nano-CaCO3 synthesis

    NASA Astrophysics Data System (ADS)

    Ulkeryildiz, Eda; Kilic, Sevgi; Ozdemir, Ekrem

    2016-09-01

    We have shown that Ca(OH)2 solution is a natural stabilizer for CaCO3 particles. We designed a CO2 bubbling crystallization reactor to produce nano-CaCO3 particles in homogenous size distribution without aggregation. In the experimental set-up, the crystallization region was separated from the stabilization region. The produced nanoparticles were removed from the crystallization region into the stabilization region before aggregation or crystal growth. It was shown that rice-like hollow nano-CaCO3 particles in about 250 nm in size were produced with almost monodispersed size distribution. The particles started to dissolve through their edges as CO2 bubbles were injected, which opened-up the pores inside the particles. At the late stages of crystallization, the open pores were closed as a result of dissolution-recrystallization of the newly synthesized CaCO3 particles. These particles were stable in Ca(OH)2 solution and no aggregation was detected. The present methodology can be used in drug encapsulation into inorganic CaCO3 particles for cancer treatment with some modifications.

  16. Ion-shaping of embedded gold hollow nanoshells into vertically aligned prolate morphologies

    NASA Astrophysics Data System (ADS)

    Coulon, Pierre-Eugéne; Amici, Julia; Clochard, Marie-Claude; Khomenkov, Vladimir; Dufour, Christian; Monnet, Isabelle; Grygiel, Clara; Perruchas, Sandrine; Ulysse, Christian; Largeau, Ludovic; Rizza, Giancarlo

    2016-02-01

    Ion beam shaping is a novel technique with which one can shape nano-structures that are embedded in a matrix, while simultaneously imposing their orientation in space. In this work, we demonstrate that the ion-shaping technique can be implemented successfully to engineer the morphology of hollow metallic spherical particles embedded within a silica matrix. The outer diameter of these particles ranges between 20 and 60 nm and their shell thickness between 3 and 14 nm. Samples have been irradiated with 74 MeV Kr ions at room temperature and for increasing fluences up to 3.8 × 1014 cm-2. In parallel, the experimental results have been theoretically simulated by using a three-dimensional code based on the thermal-spike model. These calculations show that the particles undergo a partial melting during the ion impact, and that the amount of molten phase is maximal when the impact is off-center, hitting only one hemisphere of the hollow nano-particle. We suggest a deformation scenario which differs from the one that is generally proposed for solid nano-particles. Finally, these functional materials can be seen as building blocks for the fabrication of nanodevices with really three-dimensional architecture.

  17. Ion-shaping of embedded gold hollow nanoshells into vertically aligned prolate morphologies.

    PubMed

    Coulon, Pierre-Eugéne; Amici, Julia; Clochard, Marie-Claude; Khomenkov, Vladimir; Dufour, Christian; Monnet, Isabelle; Grygiel, Clara; Perruchas, Sandrine; Ulysse, Christian; Largeau, Ludovic; Rizza, Giancarlo

    2016-01-01

    Ion beam shaping is a novel technique with which one can shape nano-structures that are embedded in a matrix, while simultaneously imposing their orientation in space. In this work, we demonstrate that the ion-shaping technique can be implemented successfully to engineer the morphology of hollow metallic spherical particles embedded within a silica matrix. The outer diameter of these particles ranges between 20 and 60 nm and their shell thickness between 3 and 14 nm. Samples have been irradiated with 74 MeV Kr ions at room temperature and for increasing fluences up to 3.8 × 10(14) cm(-2). In parallel, the experimental results have been theoretically simulated by using a three-dimensional code based on the thermal-spike model. These calculations show that the particles undergo a partial melting during the ion impact, and that the amount of molten phase is maximal when the impact is off-center, hitting only one hemisphere of the hollow nano-particle. We suggest a deformation scenario which differs from the one that is generally proposed for solid nano-particles. Finally, these functional materials can be seen as building blocks for the fabrication of nanodevices with really three-dimensional architecture.

  18. Ion-shaping of embedded gold hollow nanoshells into vertically aligned prolate morphologies

    PubMed Central

    Coulon, Pierre-Eugéne; Amici, Julia; Clochard, Marie-Claude; Khomenkov, Vladimir; Dufour, Christian; Monnet, Isabelle; Grygiel, Clara; Perruchas, Sandrine; Ulysse, Christian; Largeau, Ludovic; Rizza, Giancarlo

    2016-01-01

    Ion beam shaping is a novel technique with which one can shape nano-structures that are embedded in a matrix, while simultaneously imposing their orientation in space. In this work, we demonstrate that the ion-shaping technique can be implemented successfully to engineer the morphology of hollow metallic spherical particles embedded within a silica matrix. The outer diameter of these particles ranges between 20 and 60 nm and their shell thickness between 3 and 14 nm. Samples have been irradiated with 74 MeV Kr ions at room temperature and for increasing fluences up to 3.8 × 1014 cm−2. In parallel, the experimental results have been theoretically simulated by using a three-dimensional code based on the thermal-spike model. These calculations show that the particles undergo a partial melting during the ion impact, and that the amount of molten phase is maximal when the impact is off-center, hitting only one hemisphere of the hollow nano-particle. We suggest a deformation scenario which differs from the one that is generally proposed for solid nano-particles. Finally, these functional materials can be seen as building blocks for the fabrication of nanodevices with really three-dimensional architecture. PMID:26883992

  19. Direct electron transfer and electrochemical study of hemoglobin immobilized in ZnO hollow spheres.

    PubMed

    Liu, Changhua; Xu, Jing; Wu, Zongfang

    2011-10-01

    ZnO hollow spheres were firstly prepared. A new type of amperometric hydrogen peroxide biosensor was fabricated by entrapping Hemoglobin (Hb) through the ZnO hollow spheres (ZHS) nanoparticles. The composition morphology and size were studied by transmission electron microscopy. The surface topography of the prepared films was imaged by atomic force microscope (AFM). Several techniques, including UV-vis absorption spectroscopy, cyclic voltammetry, chronoamperometry were employed to characterize the performance of the biosensor. The results indicated that the ZHS nanoparticles had enhanced the performance of the hydrogen peroxide sensors. The electrochemical parameters of Hb in the ZHS were calculated by the results of the electron-transfer coefficient (α) and the apparent heterogeneous electron-transfer rate constant K (s) as 0.5 and 3.1 s(-1), respectively. The resulting biosensors showed a wide linear range from 2.1 × 10(-6) to 5.18 × 10(-3) M, with a low detection limit of 7.0 × 10(-7) M (S/N = 3) under optimized experimental conditions. The results demonstrated that the ZHS matrix may improve the protein loading with the retention of bioactivity and greatly promote the direct electron transfer, which can be attributed to its unique morphology, high specific surface area, and biocompatibility. The biosensor obtained from this study possesses high sensitivity, good reproducibility, and long-term stability. PMID:21505813

  20. Preparation of Magnetic Hollow Molecularly Imprinted Polymers for Detection of Triazines in Food Samples.

    PubMed

    Wang, Aixiang; Lu, Hongzhi; Xu, Shoufang

    2016-06-22

    Novel magnetic hollow molecularly imprinted polymers (M-H-MIPs) were proposed for highly selective recognition and fast enrichment of triazines in food samples. M-H-MIPs were prepared on the basis of multi-step swelling polymerization, followed by in situ growth of magnetic Fe3O4 nanoparticles on the surface of hollow molecularly imprinted polymers (H-MIPs). Transmission electron microscopy and scanning electron microscopy confirmed the successful immobilization of Fe3O4 nanoparticles on the surface of H-MIPs. M-H-MIPs could be separated simply using an external magnet. The binding adsorption results indicated that M-H-MIPs displayed high binding capacity and fast mass transfer property and class selective property for triazines. Langmuir isotherm and pseudo-second-order kinetic models fitted the best adsorption models for M-H-MIPs. M-H-MIPs were used to analyze atrazine, simazine, propazine, and terbuthylazine in corn, wheat, and soybean samples. Satisfactory recoveries were in the range of 80.62-101.69%, and relative standard deviation was lower than 5.2%. Limits of detection from 0.16 to 0.39 μg L(-1) were obtained. When the method was applied to test positive samples that were contaminated with triazines, the results agree well with those obtained from an accredited method. Thus, the M-H-MIP-based dispersive solid-phase extraction method proved to be a convenient and practical platform for detection of triazines in food samples. PMID:27257079

  1. Ion-shaping of embedded gold hollow nanoshells into vertically aligned prolate morphologies.

    PubMed

    Coulon, Pierre-Eugéne; Amici, Julia; Clochard, Marie-Claude; Khomenkov, Vladimir; Dufour, Christian; Monnet, Isabelle; Grygiel, Clara; Perruchas, Sandrine; Ulysse, Christian; Largeau, Ludovic; Rizza, Giancarlo

    2016-01-01

    Ion beam shaping is a novel technique with which one can shape nano-structures that are embedded in a matrix, while simultaneously imposing their orientation in space. In this work, we demonstrate that the ion-shaping technique can be implemented successfully to engineer the morphology of hollow metallic spherical particles embedded within a silica matrix. The outer diameter of these particles ranges between 20 and 60 nm and their shell thickness between 3 and 14 nm. Samples have been irradiated with 74 MeV Kr ions at room temperature and for increasing fluences up to 3.8 × 10(14) cm(-2). In parallel, the experimental results have been theoretically simulated by using a three-dimensional code based on the thermal-spike model. These calculations show that the particles undergo a partial melting during the ion impact, and that the amount of molten phase is maximal when the impact is off-center, hitting only one hemisphere of the hollow nano-particle. We suggest a deformation scenario which differs from the one that is generally proposed for solid nano-particles. Finally, these functional materials can be seen as building blocks for the fabrication of nanodevices with really three-dimensional architecture. PMID:26883992

  2. Nanoparticles for Enhanced Sensitivity in Electrochemical Immunoassays

    SciTech Connect

    Lin, Yuehe; Wang, Jun; Wang, Hua; Wu, Hong; Tang, Zhiwen

    2008-10-12

    In this manuscript, we report on electrochemical biosensors based on various nanoparticles (NPs) as labels for sensitive detection of protein biomarkers. We used silica nanoparticle as a carrier to loading a large amount of electroactive species such as poly(guanine) for sensitive immunoassay of tumor necrosis factor-alpha (TNF-a). We took the advantages of the unique hollow structure and reconstruction properties of apoferritin to prepare Cd3(PO4)2 nanoparticles as labels for sensitive assay of TNF-a. A novel immunochromatographic/electro-chemical biosensor based on quantum dots as labels has also been developed for rapid and sensitive detection of prostate-specific antigen (PSA) in human serum. These biosensors are quite sensitive with the detection limit at pM level and these approaches based on nanoparticle labels offer a new avenue for sensitive detection of protein biomarkers.

  3. Electrochemical Cell Design With A Hollow Gate

    DOEpatents

    Romero, Antonio; Oweis, Salah; Chagnon, Guy; Staniewicz, Robert; Briscoe, Douglas

    2000-02-01

    An electrochemical cell having a spiral winding around a central core, wherein the central core is provided with longitudinal grooves on its outer surface to facilitate electrolyte filing and accommodate overpressure. The core itself improves dissipation of heat generated along the center of the cell, and the hollow core design allows the cell core to have a larger radius, permitting the "jelly roll" winding to begin at a larger radius and thereby facilitate the initial turns of the winding by decreasing the amount of bending required of the electrode laminate at the beginning of the winding operation. The hollow core also provides mechanical support end-to-end. A pair of washers are used at each end of the cell to sandwich current collection tabs in a manner that improves electrical and thermal conductivity while also providing structural integrity.

  4. Simplified hollow-core photonic crystal fiber.

    PubMed

    Gérôme, Frédéric; Jamier, Raphaël; Auguste, Jean-Louis; Humbert, Georges; Blondy, Jean-Marc

    2010-04-15

    An original design of hollow-core photonic crystal fiber composed of a thin silica ring suspended in air by six silica struts is proposed. This structure can be viewed as a simplified Kagomé-lattice fiber reduced to one layer of air holes. By working on the core surround parameters, an efficient antiresonant air guiding was successfully demonstrated. Two large low-loss windows (visible/IR) were measured with a minimum attenuation less than 0.2 dB radicalm at yellow wavelengths, comparable with state-of-the-art designs. The curvature behavior was also studied, showing low bending loss sensitivity for the fundamental transmission band. These relevant features might open a new route to propose original hollow-core fiber designs while making their production simpler and faster than previously.

  5. Biomaterials for hollow organ tissue engineering.

    PubMed

    Hendow, Eseelle K; Guhmann, Pauline; Wright, Bernice; Sofokleous, Panagiotis; Parmar, Nina; Day, Richard M

    2016-01-01

    Tissue engineering is a rapidly advancing field that is likely to transform how medicine is practised in the near future. For hollow organs such as those found in the cardiovascular and respiratory systems or gastrointestinal tract, tissue engineering can provide replacement of the entire organ or provide restoration of function to specific regions. Larger tissue-engineered constructs often require biomaterial-based scaffold structures to provide support and structure for new tissue growth. Consideration must be given to the choice of material and manufacturing process to ensure the de novo tissue closely matches the mechanical and physiological properties of the native tissue. This review will discuss some of the approaches taken to date for fabricating hollow organ scaffolds and the selection of appropriate biomaterials. PMID:27014369

  6. Tailoring and understanding the mechanical properties of nanoparticle-shelled bubbles.

    PubMed

    Brugarolas, Teresa; Gianola, Daniel S; Zhang, Lei; Campbell, Gregory M; Bassani, John L; Feng, Gang; Lee, Daeyeon

    2014-07-23

    One common approach to generate lightweight materials with high specific strength and stiffness is the incorporation of stiff hollow microparticles (also known as bubbles or microballoons) into a polymeric matrix. The mechanical properties of these composites, also known as syntactic foams, greatly depend on those of the hollow microparticles. It is critical to precisely control the properties of these bubbles to fabricate lightweight materials that are suitable for specific applications. In this paper, we present a method to tailor the mechanical properties and response of highly monodisperse nanoparticle-shelled bubbles using thermal treatment. We characterize the mechanical properties of individual as-assembled bubbles as well as those of thermally treated ones using nanoindentation and quantitative in situ compression tests. As-assembled bubbles display inelastic response, whereas thermally treated bubbles behave elastically. We also show that the stiffness and strength of bubbles are enhanced significantly, as much as 12 and 14 times that of the as-assembled bubbles, respectively, via thermal treatment. We complement the experimental results with finite element analysis (FEA) to understand the effect of shell thickness nonuniformity as well as the inelasticity on the mechanical response and fracture behavior of these bubbles. We demonstrate that the failure mechanism of bubbles incorporated into a polymer composite depends on the structure of the bubbles.

  7. Tailoring and understanding the mechanical properties of nanoparticle-shelled bubbles.

    PubMed

    Brugarolas, Teresa; Gianola, Daniel S; Zhang, Lei; Campbell, Gregory M; Bassani, John L; Feng, Gang; Lee, Daeyeon

    2014-07-23

    One common approach to generate lightweight materials with high specific strength and stiffness is the incorporation of stiff hollow microparticles (also known as bubbles or microballoons) into a polymeric matrix. The mechanical properties of these composites, also known as syntactic foams, greatly depend on those of the hollow microparticles. It is critical to precisely control the properties of these bubbles to fabricate lightweight materials that are suitable for specific applications. In this paper, we present a method to tailor the mechanical properties and response of highly monodisperse nanoparticle-shelled bubbles using thermal treatment. We characterize the mechanical properties of individual as-assembled bubbles as well as those of thermally treated ones using nanoindentation and quantitative in situ compression tests. As-assembled bubbles display inelastic response, whereas thermally treated bubbles behave elastically. We also show that the stiffness and strength of bubbles are enhanced significantly, as much as 12 and 14 times that of the as-assembled bubbles, respectively, via thermal treatment. We complement the experimental results with finite element analysis (FEA) to understand the effect of shell thickness nonuniformity as well as the inelasticity on the mechanical response and fracture behavior of these bubbles. We demonstrate that the failure mechanism of bubbles incorporated into a polymer composite depends on the structure of the bubbles. PMID:24956417

  8. Improved method for producing small hollow spheres

    DOEpatents

    Rosencwaig, A.; Koo, J.C.; Dressler, J.L.

    An improved method and apparatus for producing small hollow spheres of glass having an outer diameter ranging from about 100..mu.. to about 500..mu.. with a substantially uniform wall thickness in the range of about 0.5 to 20..mu.. are described. The method involves introducing aqueous droplets of a glass-forming solution into a long vertical drop oven or furnace having varying temperature regions.

  9. Silicone-Rubber Tooling for Hollow Panels

    NASA Technical Reports Server (NTRS)

    Gallimore, F. H.

    1985-01-01

    Wave-free contour surface obtained by using flexible mold. Silicone-rubber layup tool, when used in conjunction with hard plastic laminating mold defining desired contour, produces panel with wave-free surface that accurately reproduces shape of mold. In addition to providing porous hollow-panel wing structure that acts as duct for transporting sucked boundary layer tooling, also used to fabricate high-strength lightweight door panels and any single-or compound-contour panel.

  10. Hollow Cathode With Multiple Radial Orifices

    NASA Technical Reports Server (NTRS)

    Brophy, John R.

    1992-01-01

    Improved hollow cathode serving as source of electrons has multiple radial orifices instead of single axial orifice. Distributes ion current more smoothly, over larger area. Prototype of high-current cathodes for ion engines in spacecraft. On Earth, cathodes used in large-diameter ion sources for industrial processing of materials. Radial orientation of orifices in new design causes current to be dispersed radially in vicinity of cathode. Advantageous where desireable to produce plasma more nearly uniform over wider region around cathode.

  11. Trapping of intense light in hollow shell

    SciTech Connect

    Luan, Shixia; Yu, Wei; Yu, M. Y.; Weng, Suming; Wang, Jingwei; Xu, Han; Zhuo, Hongbin; Wong, A. Y.

    2015-09-15

    A small hollow shell for trapping laser light is proposed. Two-dimensional particle-in-cell simulation shows that under appropriate laser and plasma conditions a part of the radiation fields of an intense short laser pulse can enter the cavity of a small shell through an over-critical density plasma in an adjacent guide channel and become trapped. The trapped light evolves into a circulating radial wave pattern until its energy is dissipated.

  12. Method for producing small hollow spheres

    DOEpatents

    Rosencwaig, Allen; Koo, Jackson C.; Dressler, John L.

    1981-01-01

    A method for producing small hollow spheres of glass having an outer diameter ranging from about 100.mu. to about 500.mu. with a substantially uniform wall thickness in the range of about 0.5-20.mu.. The method involves introducing aqueous droplets of a glass-forming solution into a long vertical drop oven or furnace having varying temperature regions. In one embodiment, one of the temperature regions is lower than both the preceeding region and the subsequent region. One region utilizes a temperature of at least 200.degree. C. higher than the melting point of the glass-forming material in the solution and, for example, may be at least 3 times higher than the temperature of the preceeding region. In addition, there is a sharp temperature gradient between these regions. As each droplet of solution passes through a first region it forms into a gel membrane having a spherical shape and encapsulates the rest of the drop retained in the elastic outer surface and the water entrapped within diffuses rapidly through the thin gel membrane which causes more of the glass-forming material to go out of solution and is incorporated into the gel membrane causing it to grow in size and become hollow. thus produced hollow glass sphere has a sphericity, concentricity, and wall uniformity of better than 5%. The sphere is capable of retaining material of up to at least 100 atmospheres therein over long periods of time. In one embodiment.

  13. Steel and titanium hollow sphere foams

    SciTech Connect

    Hurysz, K.M.; Clark, J.L.; Nagel, A.R.; Lee, K.J.; Cochran, J.K.; Sanders, T.H. Jr.; Hardwicke, C.U.

    1998-12-31

    Metal hollow sphere foams are fabricated by bonding millimeter sized metal alloy hollow spheres at points of contact. The spheres are formed as powder shells from slurries. For stainless steel spheres, the starting powder is a mixture of iron and chromium oxide. Thermal treatment in hydrogen reduces the oxides to Fe/Cr alloys with less than 2% porosity in sphere walls. The nominal composition is close to that of 405 stainless. Carburization in CO/CO{sub 2} atmosphere followed by heat treatment produces foams of either 410 or 420 type stainless steels depending on carbon content. Compressive stress-strain behavior was measured on point contact bonded stainless foams both before and after carburization. Hardness measurements on steel sphere walls were used to estimate the yield strength. Relative strengths of the foams were positioned between open and closed cell models. This was encouraging because bonding in the foams was less than optimum and the hollow sphere walls contained defects. As processing improves, strengths should increase. To produce titanium alloy spheres, the starting powder is titanium alloy hydride. Thermal treatment in an inert atmosphere decomposes the hydride and sinters the titanium powder in the sphere walls to greater than 96% relative density. Both titanium and Ti-6V-4V spheres and foams have been produced. Oxygen contents are a concern for titanium compositions and processing is being altered to reduce oxygen levels to increase ductility.

  14. Hollow Colloidosomes Prepared Using Accelerated Solvent Evaporation

    PubMed Central

    2013-01-01

    We demonstrate a new, scalable, simple, and generally applicable two-step method to prepare hollow colloidosomes. First, a high volume fraction oil-in-water emulsion was prepared. The oil phase consisted of CH2Cl2 containing a hydrophobic structural polymer, such as polycaprolactone (PCL) or polystyrene (PS), which was fed into the water phase. The water phase contained poly(vinylalcohol), poly(N-isopropylacrylamide), or a range of cationic graft copolymer surfactants. The emulsion was rotary evaporated to rapidly remove CH2Cl2. This caused precipitation of PCL or PS particles which became kinetically trapped at the periphery of the droplets and formed the shell of the hollow colloidosomes. Interestingly, the PCL colloidosomes were birefringent. The colloidosome yield increased and the polydispersity decreased when the preparation scale was increased. One example colloidosome system consisted of hollow PCL colloidosomes stabilized by PVA. This system should have potential biomaterial applications due to the known biocompatibility of PCL and PVA. PMID:24111615

  15. Spectroscopy gas sensing based on hollow fibres

    NASA Astrophysics Data System (ADS)

    Rodrigues, A.; Lange, V.; Kühlke, D.

    2011-05-01

    We demonstrate gas sensing in a relatively compact sensor unit in particular for weakly absorbing gases in real time. As a proof-of-concept, we built an oxygen sensor for the A-Band at 760 nm. A VCSEL laser was used as a laser source due to its mode stability and reduced cost compared to DFB lasers and Fabry-Perot lasers. In order to reduce as much as possible the sensor size, a hollow waveguide is used to guide the light and the gas to be analysed in a long path to enhance the sensitivity of the sensor. Two different types of hollow fibres were characterised with respect to their suitability for gas sensing, a photonic crystal fibre, also known as micro-structured optical fibre, and hollow metal-coated capillaries. Characteristics as attenuation, spectral transmission properties and filling time were analysed. At the end, a sensor device with coupling and detection unit was developed. The main advantage of our set-up is the possibility of using the same design for different gases by changing solely the laser, the detector and the coupling lens.

  16. Functionalized C@TiO2 hollow spherical architecture for multifunctional applications.

    PubMed

    Chattopadhyay, Shreyasi; Mishra, Manish Kr; De, Goutam

    2016-03-28

    Hierarchical anatase titania (TiO2) with a hollow spherical architecture decorated with functionalized carbon dots (C(F)@THS) was synthesized by a solvothermal decomposition of titanium(IV) isopropoxide (TTIP) in the presence of a solution mixture containing thiourea and citric acid. Interestingly, the concomitant presence of thiourea and citric acid has been found to be essential to obtain such hierarchical hollow architecture because individual constituents produced non-hollow spheres when hydrothermally treated with TTIP. The co-existence of these two constituents also accelerates the growth of hollow spheres. BET surface area study of C(F)@THS revealed the existence of a slit like mesoporosity with a surface area value of 81 m(2) g(-1). Time dependent FESEM and TEM studies confirmed the formation of nanoflake like structures in the intermediate stages followed by the growth of a hollow spherical architecture. We proposed that these nanoflakes get accumulated on the bubble surface to form such hollow spherical morphology. The PL spectral study and Raman shift of the as prepared C(F)@THS confirmed the presence of functionalized graphitic C dots on the surface. A thorough XPS analysis was conducted to explore the nature and relative atomic concentration of the functional groups (-COOH, -CONH2, -NH2). This C(F)@THS sample showed very fast and selective dye (methylene blue and methyl violet) adsorption ability (even from a mixture of two different dye solutions) due to these δ-site containing functional groups on the surface. As C(F)@THS showed only two times reusability for adsorption, the dye adsorbed C(F)@THS was calcined at 450 °C in air to yield organic free anatase TiO2 hollow spheres (THS) with a retention of the original structure. THS was recycled as an efficient and a reusable photocatalyst (k = 9.36 × 10(-2) min(-1)) as well as a photoanode in dye sensitized solar cells (DSSCs) having Jsc value of 19.58 mA cm(-2) with overall efficiency of 6.48%.

  17. Functionalized C@TiO2 hollow spherical architecture for multifunctional applications.

    PubMed

    Chattopadhyay, Shreyasi; Mishra, Manish Kr; De, Goutam

    2016-03-28

    Hierarchical anatase titania (TiO2) with a hollow spherical architecture decorated with functionalized carbon dots (C(F)@THS) was synthesized by a solvothermal decomposition of titanium(IV) isopropoxide (TTIP) in the presence of a solution mixture containing thiourea and citric acid. Interestingly, the concomitant presence of thiourea and citric acid has been found to be essential to obtain such hierarchical hollow architecture because individual constituents produced non-hollow spheres when hydrothermally treated with TTIP. The co-existence of these two constituents also accelerates the growth of hollow spheres. BET surface area study of C(F)@THS revealed the existence of a slit like mesoporosity with a surface area value of 81 m(2) g(-1). Time dependent FESEM and TEM studies confirmed the formation of nanoflake like structures in the intermediate stages followed by the growth of a hollow spherical architecture. We proposed that these nanoflakes get accumulated on the bubble surface to form such hollow spherical morphology. The PL spectral study and Raman shift of the as prepared C(F)@THS confirmed the presence of functionalized graphitic C dots on the surface. A thorough XPS analysis was conducted to explore the nature and relative atomic concentration of the functional groups (-COOH, -CONH2, -NH2). This C(F)@THS sample showed very fast and selective dye (methylene blue and methyl violet) adsorption ability (even from a mixture of two different dye solutions) due to these δ-site containing functional groups on the surface. As C(F)@THS showed only two times reusability for adsorption, the dye adsorbed C(F)@THS was calcined at 450 °C in air to yield organic free anatase TiO2 hollow spheres (THS) with a retention of the original structure. THS was recycled as an efficient and a reusable photocatalyst (k = 9.36 × 10(-2) min(-1)) as well as a photoanode in dye sensitized solar cells (DSSCs) having Jsc value of 19.58 mA cm(-2) with overall efficiency of 6.48%. PMID

  18. Core-decomposition-facilitated fabrication of hollow rare-earth silicate nanowalnuts from core-shell structures via the Kirkendall effect

    NASA Astrophysics Data System (ADS)

    Zhou, Wenli; Zou, Rui; Yang, Xianfeng; Huang, Ningyu; Huang, Junjian; Liang, Hongbin; Wang, Jing

    2015-08-01

    Hollow micro-/nanostructures have been widely applied in the fields of lithium ion batteries, catalysis, biosensing, biomedicine, and so forth. The Kirkendall effect, which involves a non-equilibrium mutual diffusion process, is one of many important fabrication strategies for the formation of hollow nanomaterials. Accordingly, full understanding of the interdiffusion process at the nanoscale is very important for the development of novel multifunctional hollow materials. In this work, hollow Y2SiO5 nanowalnuts have been fabricated from the conversion of YOHCO3@SiO2 core-shell nanospheres via the Kirkendall effect. More importantly, it was found that in the conversion process, the decomposition of YOHCO3 core imposes on the formation of the Y2SiO5 interlayer by facilitating the initial nucleation of the Kirkendall nanovoids and accelerating the interfacial diffusion of Y2O3@SiO2 core@shell. The simple concept developed herein can be employed as a general Kirkendall effect strategy without the assistance of any catalytically active Pt nanocrystals or gold motion for future fabrication of novel hollow nanostructures. Moreover, the photoluminescence properties of rare-earth ion doped hollow Y2SiO5 nanoparticles are researched.Hollow micro-/nanostructures have been widely applied in the fields of lithium ion batteries, catalysis, biosensing, biomedicine, and so forth. The Kirkendall effect, which involves a non-equilibrium mutual diffusion process, is one of many important fabrication strategies for the formation of hollow nanomaterials. Accordingly, full understanding of the interdiffusion process at the nanoscale is very important for the development of novel multifunctional hollow materials. In this work, hollow Y2SiO5 nanowalnuts have been fabricated from the conversion of YOHCO3@SiO2 core-shell nanospheres via the Kirkendall effect. More importantly, it was found that in the conversion process, the decomposition of YOHCO3 core imposes on the formation of the Y2Si

  19. Magnetic C-C@Fe3O4 double-shelled hollow microspheres via aerosol-based Fe3O4@C-SiO2 core-shell particles.

    PubMed

    Zhu, Yangzhi; Li, Xiangcun; He, Gaohong; Qi, Xinhong

    2015-02-18

    Magnetic C-C@Fe3O4 hollow microspheres were prepared by using aerosol-based Fe3O4@C-SiO2 core-shell particles as templates. The magnetic double-shelled microspheres efficiently worked as carriers to load Pt nanoparticles, thus making the catalyst recyclable and reusable.

  20. Review of Synthetic Methods to Form Hollow Polymer Nanocapsules

    SciTech Connect

    Barker, Madeline T.

    2014-03-13

    Syntactic foams have grown in interest due to the widened range of applications because of their mechanical strength and high damage tolerance. In the past, hollow glass or ceramic particles were used to create the pores. This paper reviews literature focused on the controlled synthesis of hollow polymer spheres with diameters ranging from 100 –200 nm. By using hollow polymer spheres, syntactic foams could reach ultra-low densities.

  1. Silica hollow spheres with nano-macroholes like diatomaceous earth.

    PubMed

    Fujiwara, Masahiro; Shiokawa, Kumi; Sakakura, Ikuko; Nakahara, Yoshiko

    2006-12-01

    Artificial synthesis of hollow cell walls of diatoms is an ultimate target of nanomaterial science. The addition of some water-soluble polymers such as sodium polymethacrylate to a solution of water/oil/water emulsion system, which is an essential step of the simple synthetic procedure of silica hollow spheres (microcapsules), led to the formation of silica hollow spheres with nano-macroholes (>100 nm) in their shell walls, the morphologies of which are analogous to those of diatom earth.

  2. Bending stresses in spherically hollow ball bearing and fatigue experiments

    NASA Technical Reports Server (NTRS)

    Nypan, L. J.; Coe, H. H.; Parker, R. J.

    1975-01-01

    Spherically hollow balls of 21.7, 50.0, and 56.5 percent mass reduction were operated in ball bearings and in a five-ball fatigue tester with differing outcomes. Available theoretical and experimental treatments of stresses in spherically hollow balls are reviewed and compared. Bending stresses are estimated for these spherically hollow balls to better understand the differences in ball bearing and fatigue test experience.

  3. Bending stresses in spherically hollow ball bearing and fatigue experiments

    NASA Technical Reports Server (NTRS)

    Nypan, L. J.; Coe, H. H.; Parker, R. J.

    1975-01-01

    Spherically hollow balls of 21.7, 50.0 and 56.5 per cent mass reduction have been operated in ball bearings and in a 5-ball fatigue tester with differing outcomes. Available theoretical and experimental treatments of stresses in spherically hollow balls are reviewed and compared. Bending stresses are estimated for these spherically hollow balls to better understand the differences in ball bearing and fatigue test experience.

  4. Novel biocompatible pH-stimuli responsive superparamagnetic hybrid hollow microspheres as tumor-specific drug delivery system.

    PubMed

    Li, Xiaorui; Du, Pengcheng; Liu, Peng

    2014-10-01

    Novel biocompatible pH-stimuli responsive superparamagnetic hybrid hollow microspheres have been designed via the layer-by-layer (LbL) self-assembly technique via the electrostatic interaction between the poly(ethylene glycol) grafted chitosan (CS-g-PEG) as polycation and the citrate modified ferroferric oxide nanoparticles (Fe3O4-CA) as hybrid anion onto the uniform polystyrene sulfonate (PSS) microsphere templates. The well-defined hybrid hollow microspheres ((CS-g-PEG/Fe3O4-CA)4/CS-g-PEG) were obtained after etching the templates by washing with DMF. They possessed superparamagnetic characteristics with a saturation magnetization of 37.23emu/g, and exhibited excellent stability in high ion-strength media and pH dependent DOX release. Their unique structure and outstanding performance make them potential platform for tumor-specific delivery in the tumor diagnostic and therapy.

  5. Precise Formation of a Hollow Carbon Nitride Structure with a Janus Surface To Promote Water Splitting by Photoredox Catalysis.

    PubMed

    Zheng, Dandan; Cao, Xu-Ning; Wang, Xinchen

    2016-09-12

    The precise modification of redox species on the inner and outer surfaces of hollow nanostructures is relevant in catalysis, surface science, and nanotechnology, but has proven difficult to achieve. Herein, we develop a facile approach to specifically fabricate Pt and Co3 O4 nanoparticles (NPs) onto the interior and exterior surface of hollow carbon nitride spheres (HCNS), respectively, to promote the surface redox functions of the polymer semiconductors. The photocatalytic water splitting activities of HCNS with spatially separated oxidation and reduction centers at their nanodomains were enhanced. The origin of the enhanced activity was attributed to the spatially separated reactive sites for the evolution of H2 and O2 and also to the unidirectional migration of the electron and hole on the Janus surfaces, thereby preventing the unwanted reverse reaction of water splitting and decreasing charge recombination. PMID:27533739

  6. Bacteria-Directed Construction of ZnO/CdS Hollow Rods and Their Enhanced Photocatalytic Activity.

    PubMed

    Ge, Shengsong; Zhang, Qiaoxia; Wang, Xiutong; Shao, Qian; Bao, Liwei; Ding, Rui; Liu, Qingyun

    2016-05-01

    Zinc oxide (ZnO) hollow rods were fabricated by precipitation method with Bacillus subtilis as template. CdS nanoparticles were then decorated on the surface of the ZnO rods through hydrothermal method. The as-prepared samples were characterized using X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscope and ultraviolet-visible spectroscopy techniques. The ZnO/CdS composite hollow rods copied the morphology of Bacillus subtiis. A possible formation mechanism of the rods was proposed. The photocatalytic activity of the samples was further evaluated through the photodegradation of Rhodamine B under a simulated solar-light irradiation. Results indicated that the photocatalytic activity of the rods improved greatly. PMID:27483848

  7. Hydrothermal synthesis of 3D hollow porous Fe3O4 microspheres towards catalytic removal of organic pollutants

    PubMed Central

    2014-01-01

    Three-dimensional hollow porous superparamagnetic Fe3O4 microspheres were synthesized via a facile hydrothermal process. A series of characterizations done with X-ray diffraction, Brunauer-Emmett-Teller method, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy indicated that the production of Fe3O4 microspheres possessed good monodispersity, uniform size distribution, hollow and porous structural characters, and strong superparamagnetic behavior. The obtained Fe3O4 microspheres have a diameter of ca. 300 nm, which is composed of many interconnected nanoparticles with a size of ca. 20 nm. The saturation magnetization is 80.6 emu·g-1. The as-prepared products had promising applications as novel catalysts to remove organic pollutants (methylene blue) from wastewater in the presence of H2O2 and ultrasound irradiation. PMID:25520596

  8. Precise Formation of a Hollow Carbon Nitride Structure with a Janus Surface To Promote Water Splitting by Photoredox Catalysis.

    PubMed

    Zheng, Dandan; Cao, Xu-Ning; Wang, Xinchen

    2016-09-12

    The precise modification of redox species on the inner and outer surfaces of hollow nanostructures is relevant in catalysis, surface science, and nanotechnology, but has proven difficult to achieve. Herein, we develop a facile approach to specifically fabricate Pt and Co3 O4 nanoparticles (NPs) onto the interior and exterior surface of hollow carbon nitride spheres (HCNS), respectively, to promote the surface redox functions of the polymer semiconductors. The photocatalytic water splitting activities of HCNS with spatially separated oxidation and reduction centers at their nanodomains were enhanced. The origin of the enhanced activity was attributed to the spatially separated reactive sites for the evolution of H2 and O2 and also to the unidirectional migration of the electron and hole on the Janus surfaces, thereby preventing the unwanted reverse reaction of water splitting and decreasing charge recombination.

  9. A novel strategy to directly fabricate flexible hollow nanofibers with tunable luminescence-electricity-magnetism trifunctionality using one-pot electrospinning.

    PubMed

    Liu, Yawen; Ma, Qianli; Dong, Xiangting; Yu, Wensheng; Wang, Jinxian; Liu, Guixia

    2015-09-21

    Novel photoluminescent-electrical-magnetic trifunctional flexible Eu(BA)3phen/PANI/Fe3O4/PVP (BA = benzoic acid, phen = phenanthroline, PANI = polyaniline, PVP = polyvinylpyrrolidone) hollow nanofibers were fabricated by a one-pot electrospinning technique using a specially designed coaxial spinneret for the first time. Very different from the traditional preparation process of hollow fibers via coaxial electrospinning, which needs to firstly fabricate the coaxial fibers and followed by removing the core through high-temperature calcination or solvent extraction, in our current study, no core spinning solution is used to directly fabricate hollow nanofibers. The morphology and properties of the obtained hollow nanofibers were characterized in detail using X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, fluorescence spectroscopy, Fourier-transform infrared spectroscopy, a 4-point probe resistivity measurement system and vibrating sample magnetometry. The Eu(BA)3phen/PANI/Fe3O4/PVP hollow nanofibers, with outer diameters of ca. 305 nm and inner diameters of about 140 nm, exhibit excellent photoluminescence performance, electrical conductivity and magnetic properties. Fluorescence emission peaks of Eu(3+) are observed in the Eu(BA)3phen/PANI/Fe3O4/PVP hollow nanofibers and assigned to the (5)D0→(7)F0 (580 nm), (5)D0→(7)F1 (592 nm) and (5)D0→(7)F2 (616 nm) energy level transitions of Eu(3+) ions, and the (5)D0→(7)F2 hypersensitive transition at 616 nm is the predominant emission peak. The electrical conductivity of the hollow nanofibers reaches up to the order of 10(-3) S cm(-1). The luminescent intensity, electrical conductivity and magnetic properties of the hollow nanofibers can be tuned by adding various amounts of Eu(BA)3phen, PANI and Fe3O4 nanoparticles. The new-type photoluminescent-electrical-magnetic trifunctional flexible hollow nanofibers hold potential for a variety of applications, including electromagnetic

  10. Hollow CoP nanopaticle/N-doped graphene hybrids as highly active and stable bifunctional catalysts for full water splitting

    NASA Astrophysics Data System (ADS)

    Yu, Xianbo; Zhang, Shen; Li, Chunyan; Zhu, Chunling; Chen, Yujin; Gao, Peng; Qi, Lihong; Zhang, Xitian

    2016-05-01

    An alkaline electrolyzer fabricated by employing hollow CoP nanoparticles/N-doped graphene as bifunctional catalysts exhibits remarkable activity with a current density of 10 mA cm-2 at a cell voltage of 1.58 V and considerable stability over 65 h of continuous electrolysis operation, favorably comparable to the integrated performance of commercial Pt/C and IrO2.An alkaline electrolyzer fabricated by employing hollow CoP nanoparticles/N-doped graphene as bifunctional catalysts exhibits remarkable activity with a current density of 10 mA cm-2 at a cell voltage of 1.58 V and considerable stability over 65 h of continuous electrolysis operation, favorably comparable to the integrated performance of commercial Pt/C and IrO2. Electronic supplementary information (ESI) available: Detailed experimental procedures, Fig. S1-S17 and Tables S1-S5. See DOI: 10.1039/c6nr01867j

  11. Hollow Au/Ag nanostars displaying broad plasmonic resonance and high surface-enhanced Raman sensitivity

    NASA Astrophysics Data System (ADS)

    Garcia-Leis, Adianez; Torreggiani, Armida; Garcia-Ramos, Jose Vicente; Sanchez-Cortes, Santiago

    2015-08-01

    Bimetallic Au/Ag hollow nanostar (HNS) nanoparticles with different morphologies were prepared in this work. These nanoplatforms were obtained by changing the experimental conditions (concentration of silver and chemical reductors, hydroxylamine and citrate) and by using Ag nanostars as template nanoparticles (NPs) through galvanic replacement. The goal of this research was to create bimetallic Au/Ag star-shaped nanoparticles with advanced properties displaying a broader plasmonic resonance, a cleaner exposed surface, and a high concentration of electromagnetic hot spots on the surface provided by the special morphology of nanostars. The size, shape, and composition of Ag as well as their optical properties were studied by extinction spectroscopy, hyperspectral dark field microscopy, transmission and scanning electron microscopy (TEM and SEM), and energy dispersive X-ray spectroscopy (EDX). Finally, the surface-enhanced Raman scattering (SERS) activity of these HNS was investigated by using thioflavin T, a biomarker of the β-amyloid fibril formation, responsible for Alzheimer's disease. Lucigenin, a molecule displaying different SERS activities on Au and Ag, was also used to explore the presence of these metals on the NP surface. Thus, a relationship between the morphology, plasmon resonance and SERS activity of these new NPs was made.Bimetallic Au/Ag hollow nanostar (HNS) nanoparticles with different morphologies were prepared in this work. These nanoplatforms were obtained by changing the experimental conditions (concentration of silver and chemical reductors, hydroxylamine and citrate) and by using Ag nanostars as template nanoparticles (NPs) through galvanic replacement. The goal of this research was to create bimetallic Au/Ag star-shaped nanoparticles with advanced properties displaying a broader plasmonic resonance, a cleaner exposed surface, and a high concentration of electromagnetic hot spots on the surface provided by the special morphology of nanostars

  12. Synthesis and enhanced visible-light responsive of C,N,S-tridoped TiO2 hollow spheres.

    PubMed

    Lin, Xiaoxia; Fu, Degang; Hao, Lingyun; Ding, Zhen

    2013-10-01

    C,N,S-tridoped TiO2 hollow spheres (labeled as C,N,S-THs) were synthesized using carbon spheres as template and C,N,S-tridoped TiO2 nanoparticles as building blocks. The structure and physicochemical properties of the catalysts were characterized by Xray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis diffuse reflectance spectrum (DRS), N2 adsorption-desorption isotherms, X-ray photoelectron spectroscopy (XPS) and Photoluminescence emission spectroscopy (PL). The results showed that the hollow spheres had average diameter of about 200 nm and the shell thickness was about 20 nm. The tridoped TiO2 hollow spheres exhibited strong absorption in the visible-light region. C,N,S-tridoped could narrow the band gap of the THs by mixing the orbit O 2p with C 2p, N 2p and S 3p orbits and shift its optical response from ultraviolet (UV) to the visible-light region. PL analysis indicated that the electron-hole recombination rate of TiO2 hollow spheres had been effectively inhibited when doped with C, N and S elements. The photocatalytic activities of the samples were evaluated for the degradation of X-3B (Reactive Brilliant Red dye, C.I. Reactive Red 2) aqueous solution under visible-light (lambda > 420 nm) irradiation. It was found that the C,N,S-tridoped TiO2 hollow spheres indicated higher photocatalytic activity than commercial P25 and the undoped counterpart photocatalyst.

  13. Coated gas bubbles for the continuous synthesis of hollow inorganic particles.

    PubMed

    Wan, Jiandi; Stone, Howard A

    2012-01-10

    We present a microfluidic approach for the controlled encapsulation of individual gas bubbles in micrometer-diameter aqueous droplets with high gas volume fractions and demonstrate this approach to making a liquid shell, which serves as a template for the synthesis of hollow inorganic particles. In particular, we find that an increase in the viscosity of the aqueous phase facilitates the encapsulation of individual gas bubbles in an aqueous droplet and allows control of the thickness of a thin aqueous shell. Furthermore, because such droplets contain a finite amount of water, uncontrolled hydrolysis reactions between reactive inorganic precursors and bulk water can be avoided. We demonstrate this approach by introducing reactive inorganic precursors, such as silane and titanium butoxide, for sol-gel reactions downstream from the formation of the bubble in a droplet and consequently fabricate hollow particles of silica or titania in one continuous flow process. These approaches provide a route to controlling double-emulsion-type gas-liquid microstructures and offer a new fabrication method for thin-shell-covered microbubbles and hollow microparticles.

  14. Method and apparatus for producing concentric hollow spheres. [inertial confinement fusion targets

    NASA Technical Reports Server (NTRS)

    Wang, T. G.; Elleman, D. D. (Inventor)

    1981-01-01

    Hollow spheres with precisely concentric inner and outer spherical surfaces are formed by applying vibrations to a nonconcentric hollow sphere while it is at an elevated temperature at which it is fluid or plastic, the vibrations producing internal flows which cause the inner and outer surfaces to become precisely concentric. Concentric spheres can be mass produced by extruding a material such as glass or metal while injecting a stream of gas into the center of the extrusion to form a gas-filled tube. Vibrations are applied to the extruded tube to help break it up into individual bodies of a desired uniform size, the bodies tending to form spherical inner and outer surfaces by reason of surface tension, and the continuing application of vibrations causing these surfaces to become concentric.

  15. Lactobacillus assisted synthesis of titanium nanoparticles

    NASA Astrophysics Data System (ADS)

    Prasad, K.; Jha, Anal K.; Kulkarni, A. R.

    2007-05-01

    An eco-friendly lactobacillus sp. (microbe) assisted synthesis of titanium nanoparticles is reported. The synthesis is performed at room temperature. X-ray and transmission electron microscopy analyses are performed to ascertain the formation of Ti nanoparticles. Individual nanoparticles as well as a number of aggregates almost spherical in shape having a size of 40 60 nm are found.

  16. Uniform Ni/SiO2@Au magnetic hollow microspheres: rational design and excellent catalytic performance in 4-nitrophenol reduction.

    PubMed

    Zhang, Shenghuan; Gai, Shili; He, Fei; Dai, Yunlu; Gao, Peng; Li, Lei; Chen, Yujin; Yang, Piaoping

    2014-06-21

    A unique and rational design was presented to fabricate Ni/SiO2@Au magnetic hollow microspheres (MHMs) with interesting structures and well-dispersed metal nanoparticles. Hierarchical nickel silicate hollow microspheres were synthesized using silica colloidal spheres as a chemical template. Then, Ni/SiO2 MHMs with well-dispersed Ni nanoparticles were prepared via an in situ reduction approach. Ni/SiO2@Au MHMs were finally obtained by immobilizing uniform Au nanoparticles onto Ni/SiO2 support through a low-temperature chemical reduction process. It was found that Ni/SiO2@Au MHMs inherit the shape and uniformity of the original silica scaffold, and Ni NPs and Au NPs, which were less than 5 nm in size, were well dispersed on the mesoporous silica shell with narrow size distribution. Both Ni/SiO2 and Ni/SiO2@Au MHMs showed excellent catalytic activity in the 4-nitrophenol reduction reaction. Importantly, introduction of a small amount of Au NPs onto Ni/SiO2 MHMs markedly improved the catalytic activity. In particular, Ni/SiO2@Au MHMs showed high conversion even after re-use for several cycles with magnetic separation. The unique structure, high catalytic performance, and ease of separation make Ni/SiO2@Au MHMs highly promising candidates for diverse applications.

  17. Co-Flow Hollow Cathode Technology

    NASA Technical Reports Server (NTRS)

    Hofer, Richard R.; Goebel, Dan M.

    2011-01-01

    Hall thrusters utilize identical hollow cathode technology as ion thrusters, yet must operate at much higher mass flow rates in order to efficiently couple to the bulk plasma discharge. Higher flow rates are necessary in order to provide enough neutral collisions to transport electrons across magnetic fields so that they can reach the discharge. This higher flow rate, however, has potential life-limiting implications for the operation of the cathode. A solution to the problem involves splitting the mass flow into the hollow cathode into two streams, the internal and external flows. The internal flow is fixed and set such that the neutral pressure in the cathode allows for a high utilization of the emitter surface area. The external flow is variable depending on the flow rate through the anode of the Hall thruster, but also has a minimum in order to suppress high-energy ion generation. In the co-flow hollow cathode, the cathode assembly is mounted on thruster centerline, inside the inner magnetic core of the thruster. An annular gas plenum is placed at the base of the cathode and propellant is fed throughout to produce an azimuthally symmetric flow of gas that evenly expands around the cathode keeper. This configuration maximizes propellant utilization and is not subject to erosion processes. External gas feeds have been considered in the past for ion thruster applications, but usually in the context of eliminating high energy ion production. This approach is adapted specifically for the Hall thruster and exploits the geometry of a Hall thruster to feed and focus the external flow without introducing significant new complexity to the thruster design.

  18. Hollow-Fiber Spacesuit Water Membrane Evaporator

    NASA Technical Reports Server (NTRS)

    Bue, Grant; Trevino, Luis; Tsioulos, Gus; Mitchell, Keith; Settles, Joseph

    2013-01-01

    The hollow-fiber spacesuit water membrane evaporator (HoFi SWME) is being developed to perform the thermal control function for advanced spacesuits and spacecraft to take advantage of recent advances in micropore membrane technology in providing a robust, heat-rejection device that is less sensitive to contamination than is the sublimator. After recent contamination tests, a commercial-off-the-shelf (COTS) micro porous hollow-fiber membrane was selected for prototype development as the most suitable candidate among commercial hollow-fiber evaporator alternatives. An innovative design that grouped the fiber layers into stacks, which were separated by small spaces and packaged into a cylindrical shape, was developed into a full-scale prototype for the spacesuit application. Vacuum chamber testing has been performed to characterize heat rejection as a function of inlet water temperature and water vapor back-pressure, and to show contamination resistance to the constituents expected to be found in potable water produced by the wastewater reclamation distillation processes. Other tests showed tolerance to freezing and suitability to reject heat in a Mars pressure environment. In summary, HoFi SWME is a lightweight, compact evaporator for heat rejection in the spacesuit that is robust, contamination- insensitive, freeze-tolerant, and able to reject the required heat of spacewalks in microgravity, lunar, and Martian environments. The HoFi is packaged to reject 810 W of heat through 800 hours of use in a vacuum environment, and 370 W in a Mars environment. The device also eliminates free gas and dissolved gas from the coolant loop.

  19. Casting of particle-based hollow shapes

    DOEpatents

    Menchhofer, Paul

    1997-01-01

    A method for the production of hollow articles made of a particle-based material; e.g., ceramics and sintered metals. In accordance with one aspect of the invention, a thermally settable slurry containing a relatively high concentration of the particles is coated onto a prewarmed continuous surface in a relatively thin layer so that the slurry is substantially uniformly coated on the surface. The heat of the prewarmed surface conducts to the slurry to initiate a reaction which causes the slurry to set or harden in a shape conforming to the surface. The hardened configurations may then be sintered to consolidate the particles and provide a high density product.

  20. Casting of particle-based hollow shapes

    DOEpatents

    Menchhofer, Paul

    1995-01-01

    A method for the production of hollow articles made of a particle-based material; e.g., ceramics and sintered metals. In accordance with one aspect of the invention, a thermally settable slurry containing a relatively high concentration of the particles is coated onto a prewarmed continuous surface in a relatively thin layer so that the slurry is substantially uniformly coated on the surface. The heat of the prewarmed surface conducts to the slurry to initiate a reaction which causes the slurry to set or harden in a shape conforming to the surface. The hardened configurations may then be sintered to consolidate the particles and provide a high density product.

  1. Why are so many trees hollow?

    PubMed

    Ruxton, Graeme D

    2014-11-01

    In many living trees, much of the interior of the trunk can be rotten or even hollowed out. Previously, this has been suggested to be adaptive, with microbial or animal consumption of interior wood producing a rain of nutrients to the soil beneath the tree that allows recycling of those nutrients into new growth via the trees roots. Here I propose an alternative (non-exclusive) explanation: such loss of wood comes at very little cost to the tree and so investment in costly chemical defence of this wood is not economic. I discuss how this theory can be tested empirically. PMID:25392312

  2. Why are so many trees hollow?

    PubMed Central

    Ruxton, Graeme D.

    2014-01-01

    In many living trees, much of the interior of the trunk can be rotten or even hollowed out. Previously, this has been suggested to be adaptive, with microbial or animal consumption of interior wood producing a rain of nutrients to the soil beneath the tree that allows recycling of those nutrients into new growth via the trees roots. Here I propose an alternative (non-exclusive) explanation: such loss of wood comes at very little cost to the tree and so investment in costly chemical defence of this wood is not economic. I discuss how this theory can be tested empirically. PMID:25392312

  3. LHC particle collimation with hollow electron beams

    SciTech Connect

    Shiltsev, V.; Drozhdin, A.; Kamerdzhiev, V.; Kuznetsov, G.; Vorobiev, L.; /Fermilab

    2008-06-01

    Electron lenses built and installed in the Tevatron have proven themselves as safe and very reliable instruments which can be effectively used in hadron collider operation for a number of applications, including compensation of beam-beam effects [1], a DC beam removal from abort gaps [2], and as a versatile diagnostic tool. In this article, we--following the original proposal [3,4]--consider in more detail a possibility of using electron lenses with hollow electron beam for ion and proton collimation in LHC and the Tevatron.

  4. Polarization Labeling Spectroscopy of Hollow Lithium

    NASA Astrophysics Data System (ADS)

    Huang, M.-T.; Wehlitz, R.; Cherepkov, N. A.; Azuma, Y.; Depaola, B. D.; Nagata, T.; Hasegawa, S.; Levin, J. C.; Sellin, I. A.

    1998-05-01

    Utilization of polarized or aligned targets can provide valuable information on atomic photoionization and excitation processes. (M. Meyer et al.), Phys. Rev. Lett. 59, 2963 (1987) We measured numerous even-parity doubly core excited ``hollow lithium'' resonances using monchromatized synchrotron radiation derived from an undulator, and laser excited lithium targets. The excited 1s^22p ^2Po targets, were aligned or polarized by laser pumping, and measurements were made with various combinations with the polarization of synchrotron radiation. The intensity pattern of the photoion spectrum shows clear polarization dependence and provides useful clues to the analysis.

  5. Hollow-Cathode Source Generates Plasma

    NASA Technical Reports Server (NTRS)

    Deininger, W. D.; Aston, G.; Pless, L. C.

    1989-01-01

    Device generates argon, krypton, or xenon plasma via thermionic emission and electrical discharge within hollow cathode and ejects plasma into surrounding vacuum. Goes from cold start up to full operation in less than 5 s after initial application of power. Exposed to moist air between operations without significant degradation of starting and running characteristics. Plasma generated by electrical discharge in cathode barrel sustained and aided by thermionic emission from emitter tube. Emitter tube does not depend on rare-earth oxides, making it vulnerable to contamination by exposure to atmosphere. Device modified for use as source of plasma in laboratory experiments or industrial processes.

  6. Anti-resonant hexagram hollow core fibers.

    PubMed

    Hayes, John R; Poletti, Francesco; Abokhamis, Mousavi S; Wheeler, Natalie V; Baddela, Naveen K; Richardson, David J

    2015-01-26

    Various simple anti-resonant, single cladding layer, hollow core fiber structures are examined. We show that the spacing between core and jacket glass and the shape of the support struts can be used to optimize confinement loss. We demonstrate the detrimental effect on confinement loss of thick nodes at the strut intersections and present a fabricated hexagram fiber that mitigates this effect in both straight and bent condition by presenting thin and radially elongated nodes. This fiber has loss comparable to published results for a first generation, multi-cladding ring, Kagome fiber with negative core curvature and has tolerable bend loss for many practical applications.

  7. Nonlinear sequential laminates reproducing hollow sphere assemblages

    NASA Astrophysics Data System (ADS)

    Idiart, Martín I.

    2007-07-01

    A special class of nonlinear porous materials with isotropic 'sequentially laminated' microstructures is found to reproduce exactly the hydrostatic behavior of 'hollow sphere assemblages'. It is then argued that this result supports the conjecture that Gurson's approximate criterion for plastic porous materials, and its viscoplastic extension of Leblond et al. (1994), may actually yield rigorous upper bounds for the hydrostatic flow stress of porous materials containing an isotropic, but otherwise arbitrary, distribution of porosity. To cite this article: M.I. Idiart, C. R. Mecanique 335 (2007).

  8. Hollow ballistic pendulum for plasma momentum measurements

    SciTech Connect

    Goncharov, S.F.; Pashinin, P.P.; Perov, V.Y.; Serov, R.V.; Yanovsky, V.P.

    1988-05-01

    A novel pendulum design: hollow ballistic pendulum: is suggested for plasma momentum measurements. It has an advantage over the pendula used earlier in laser plasma experiments of being insensitive to a momentum of matter evaporated and scattered by the pendulum wall exposed to the plasma, which usually exceeds plasma momentum to be measured. Simple expressions describing pendulum performance are derived, and requirements of shape and size are established. Using this kind of pendulum in experiments on laser acceleration of thin foils made it possible to measure the momentum of accelerated foil with an accuracy of about 10%.

  9. Hollow Blocks: How to Make and Use Them.

    ERIC Educational Resources Information Center

    Texas Child Care, 1993

    1993-01-01

    Provides detailed plans for the construction of 11-by-11-by-5.5-inch hollow wooden blocks that can be constructed with simple tools by child-care providers and parents. Children's play with hollow blocks, which can also be constructed half- and double-size, allows them to develop muscular coordination and assists in their social and emotional…

  10. Fabrication of Closed Hollow Bulb Obturator Using Thermoplastic Resin Material.

    PubMed

    Shrestha, Bidhan; Hughes, E Richard; Kumar Singh, Raj; Suwal, Pramita; Parajuli, Prakash Kumar; Shrestha, Pragya; Sharma, Arati; Adhikari, Galav

    2015-01-01

    Purpose. Closed hollow bulb obturators are used for the rehabilitation of postmaxillectomy patients. However, the time consuming process, complexity of fabrication, water leakage, and discoloration are notable disadvantages of this technique. This paper describes a clinical report of fabricating closed hollow bulb obturator using a single flask and one time processing method for an acquired maxillary defect. Hard thermoplastic resin sheet has been used for the fabrication of hollow bulb part of the obturator. Method. After fabrication of master cast conventionally, bulb and lid part of the defect were formed separately and joined by autopolymerizing acrylic resin to form one sized smaller hollow body. During packing procedure, the defect area was loaded with heat polymerizing acrylic resin and then previously fabricated smaller hollow body was adapted over it. The whole area was then loaded with heat cure acrylic. Further processes were carried out conventionally. Conclusion. This technique uses single flask which reduces laboratory time and makes the procedure simple. The thickness of hollow bulb can be controlled and light weight closed hollow bulb prosthesis can be fabricated. It also minimizes the disadvantages of closed hollow bulb obturator such as water leakage, bacterial infection, and discoloration.

  11. Construction of Apalachee Parkway Through the Smokey Hollow Community ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Construction of Apalachee Parkway Through the Smokey Hollow Community - The Smokey Hollow Community, Informal boundaries by street name: North to South: East Jefferson Street to East Van Buren Street. West to East: South Gadsden Street to Marvin Street., Tallahassee, Leon County, FL

  12. Combined plasma and thermal hollow cathode insert model

    NASA Technical Reports Server (NTRS)

    Katz, Ira; Polk, James E.; Mikellides, Ionnis G.; Goebel, Dan m.; Hornbeck, Sarah E.

    2005-01-01

    In this paper, we present the first results from a Hollow Cathode Thermal (HCThermal) model that uses the spatially distributed plasma fluxes calculated by the InsertRegion of an Orificed Cathode (IROrCa2D) code as the heat source to predict the hollow cathode and insert temperatures.

  13. Porous-wall hollow glass microspheres as carriers for biomolecules

    DOEpatents

    Li, Shuyi; Dynan, William S; Wicks, George; Serkiz, Steven

    2013-09-17

    The present invention includes compositions of porous-wall hollow glass microspheres and one or more biomolecules, wherein the one or more biomolecules are positioned within a void location within the hollow glass microsphere, and the use of such compositions for the diagnostic and/or therapeutic delivery of biomolecules.

  14. Self-contained hot-hollow cathode gun source assembly

    DOEpatents

    Zeren, Joseph D.

    1986-01-01

    A self-contained hot-hollow cathode gun source assembly for use in a vacuum chamber includes a crucible block having a hot-hollow cathode gun mounted underneath and providing a hole for the magnetic deflection of the ion/electron beam into a crucible on top the block.

  15. Self-contained hot-hollow cathode gun source assembly

    DOEpatents

    Zeren, J.D.

    1984-08-01

    A self-contained hot-hollow cathode gun source assembly for use in a vacuum chamber includes a crucible block having a hot-hollow cathode gun mounted underneath and providing a hole for the magnetic deflection of the ion/electron beam into a crucible on top the block.

  16. Simple Spinning of Heterogeneous Hollow Microfibers on Chip.

    PubMed

    Yu, Yue; Wei, Wenbo; Wang, Yaqing; Xu, Cong; Guo, Yaqiong; Qin, Jianhua

    2016-08-01

    A novel and simple chip-based microfluidic strategy is proposed for continuously controlled spinning of desirable hollow microfibers. These fabricated fiber-shaped materials exhibit extraordinary morphological and structural complexity, as well as a heterogeneous composition. The resulting specific hollow microfibers have potential applications in numerous chemical and biomedical fields.

  17. Fabrication of Closed Hollow Bulb Obturator Using Thermoplastic Resin Material

    PubMed Central

    Shrestha, Bidhan; Hughes, E. Richard; Kumar Singh, Raj; Suwal, Pramita; Parajuli, Prakash Kumar; Shrestha, Pragya; Sharma, Arati; Adhikari, Galav

    2015-01-01

    Purpose. Closed hollow bulb obturators are used for the rehabilitation of postmaxillectomy patients. However, the time consuming process, complexity of fabrication, water leakage, and discoloration are notable disadvantages of this technique. This paper describes a clinical report of fabricating closed hollow bulb obturator using a single flask and one time processing method for an acquired maxillary defect. Hard thermoplastic resin sheet has been used for the fabrication of hollow bulb part of the obturator. Method. After fabrication of master cast conventionally, bulb and lid part of the defect were formed separately and joined by autopolymerizing acrylic resin to form one sized smaller hollow body. During packing procedure, the defect area was loaded with heat polymerizing acrylic resin and then previously fabricated smaller hollow body was adapted over it. The whole area was then loaded with heat cure acrylic. Further processes were carried out conventionally. Conclusion. This technique uses single flask which reduces laboratory time and makes the procedure simple. The thickness of hollow bulb can be controlled and light weight closed hollow bulb prosthesis can be fabricated. It also minimizes the disadvantages of closed hollow bulb obturator such as water leakage, bacterial infection, and discoloration. PMID:26491575

  18. Hollow Promises: A Window into Mercury’s Surface Mineralogy

    NASA Astrophysics Data System (ADS)

    Vilas, Faith; Domingue, Deborah L.; Helbert, Joern; D'Amore, Mario; Izenberg, Noam R.; Murchie, Scott L.; Klima, Rachel L.; Stockstill-Cahill, Karen R.; Sprague, Ann L.; Vaughan, William M.; Head, James W.

    2014-11-01

    Early in its orbital operations at Mercury, the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft’s Mercury Dual-Imaging System (MDIS) began imaging "hollows" on the walls, rims, floors, and central peaks of impact craters. Hollows are shallow, irregular, rimless, flat-floored depressions, often with bright interiors and halos, are fresh in appearance, and have less steeply sloped spectral reflectance with wavelength than typical for Mercury. MDIS wide-angle camera (WAC) images obtained with eight narrow-band color filters from 433.2 nm to 996.2 nm of hollows in the craters Dominici (center latitude 1.38°N, longitude 323.5°E, ~20 km diameter), Hopper (12.4°S, 304.1°E, ~35 km), and Mistral (4.7°N, 305.4°E, ~100 km) have sufficient spatial resolution and repeatable color sets to examine spectral reflectance properties. The reflectance data, expressed as I/F, where I is light reflected from Mercury's surface and F is incident sunlight, were corrected for global geometric effects. Hollows on the south crater wall and rim of Dominici have well-defined depressions and halos that are a factor of ~1.4 brighter across the spectral range measured than those in the crater center. Hollows in the center of Dominici are factor of ~1.2 brighter than those in Hopper and Mistral. Eight color sets of Dominici show evidence for a spectral absorption feature centered near 700 nm in the hollows terrain. Three color sets of Hopper hollows show a spectral absorption feature diminished in depth compared to that for the Dominici hollows; the Mistral hollows show no discernible spectral absorption in two color sets. The reflectance differences are likely due to relative age of the hollows. At Dominici, we postulate that the hollows on the southern wall and rim were exposed to the local environment through a process of slumping of overlying material; it is likely that fresh material susceptible to hollow formation is regularly exposed. Local and

  19. Hollow Casein-Based Polymeric Nanospheres for Opaque Coatings.

    PubMed

    Zhang, Fan; Ma, Jianzhong; Xu, Qunna; Zhou, Jianhua; Simion, Demetra; Carmen, Gaidău; Wang, John; Li, Yunqi

    2016-05-11

    Casein-based hollow polymeric sphere were fabricated through emulsifier-free polymerization coupled with alkali swelling approach. Hollow structure and nanoscale size of casein-based polymeric spheres were verified by TEM, AFM, SEM, and UV-vis spectra. The as-obtained hollow spheres were proved exhibiting superior opaque characteristic. Through adjusting the structural parameters, for example, MAA usages and MAA content in seed to core, sphere film showed tunable visible-light transmittance and antiultraviolet property. The formation mechanism of casein-based hollow sphere has been discussed in depth. Worth mentioning, the resultant hollow polymeric sphere can easily form films itself at room temperature, which would open a new possibility of designing opaque coatings in several fields, such as leather, packaging, paper making, biomedical, and special indoor coating applications.

  20. Hollow fiber bioreactor technology for tissue engineering applications.

    PubMed

    Eghbali, Hadis; Nava, Michele M; Mohebbi-Kalhori, Davod; Raimondi, Manuela T

    2016-01-01

    Hollow fiber bioreactors are the focus of scientific research aiming to mimic physiological vascular networks and engineer organs and tissues in vitro. The reason for this lies in the interesting features of this bioreactor type, including excellent mass transport properties. Indeed, hollow fiber bioreactors allow limitations to be overcome in nutrient transport by diffusion, which is often an obstacle to engineer sizable constructs in vitro. This work reviews the existing literature relevant to hollow fiber bioreactors in organ and tissue engineering applications. To this purpose, we first classify the hollow fiber bioreactors into 2 categories: cylindrical and rectangular. For each category, we summarize their main applications both at the tissue and at the organ level, focusing on experimental models and computational studies as predictive tools for designing innovative, dynamic culture systems. Finally, we discuss future perspectives on hollow fiber bioreactors as in vitro models for tissue and organ engineering applications.